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  • Articles  (1,229)
  • Polymer and Materials Science  (1,229)
  • Inorganic Chemistry
  • 2015-2019
  • 1990-1994  (1,229)
  • 1915-1919
  • Technology  (1,028)
  • Electrical Engineering, Measurement and Control Technology  (201)
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  • Articles  (1,229)
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  • 1
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994) 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050101
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  • 2
    Electronic Resource
    Electronic Resource
    Metallic wear debris in metal-backed patellar failure (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 9-16 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Eight patients with failure of metal-backed patellar components were studied for evidence of intraarticular and systemic metal deposition. Seven of the eight patients had failure of a titanium-based patellar component that then articulated with a cobaltchromium femoral component. One patient had articulation of a cobalt-chromium patellar component against a cobalt-chromium femoral component. All components failed by the same pattern of failure. Wearing of the ultra high molecular weight polyethylene was followed by displacement of the polyethylene and then metal-to-metal contact of the components.Methods for analysis of the debris included light and electron microscopy of synovial tissue and electron dispersive x-ray analysis (EDAX) of tissue. Graphite furnace atomic absorption spectroscopy (GFAAS) was done on synovial fluid and synovial tissue as well as urine and blood specimens taken at various times from implantation to patellar revision.Massive deposition of metallic debris within the knee joint was documented both histologically and by GFAAS. Titanium levels reached as high as 2776 ppm (mg/L) in the synovial fluid and as high as 917 mg/g of synovial tissue. Elevation of all the pertinent metals was seen in the tissue and body fluids. Titanium and aluminum levels were the highest. Titanium levels in the serum generally were highest near the time of implant failure. Other metal elevations were variable and could not be related to the time of failure. Synovial fluid levels of all metals and serum levels of titanium are reflective of intraarticular generation of metallic debris.This study demonstrates that in situations of failure of a device, massive intraarticular debris generation occurs and systemic transport will occur. To date no systemic consequences can be attributed to the deposition of debris and follow-up urine and blood specimens suggest that debridement and revision of the failed device results in lowering of the ion levels. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050103
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of polyesterurethane degradation products (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 1-7 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Microthane foam, a poly(ester)urethane, used as a covering of some breast implants (Meme or Replicon by Surgitek) degrades readily in phosphate buffer pH 7.4 producing multiple unknown products in addition to 2,4 and 2,6 toluenediamine (TDA). The cumulative weight loss of the foam in buffer was 1.5% at 1 week and 2% at 2 weeks. Multiple peak molecular weights from 105 to 665 000 were found in the aqueous foam extracts following 2 weeks of incubation at 37°C using size exclusion chromatography (SEC). TDA was measured in the foam buffer extracts by high pressure liquid chromatography (HPLC) and confirmed by gas chromatography/mass spectroscopy (GC/MS). The total cumulative levels of 2,4 TDA and 2,6 TDA measured were 3 ± 0.65 μg/g of foam and 1.13 ± 0.19 μg/g of foam following 36 days of incubation at 37 °C. Higher amounts, 8.96 μg/g of 2,4 TDA and 3.3 μg/g of 2,6 TDA, were obtained at 50 °C. The cumulative release of TDA in aqueous extracts was found to correlate linearly with time suggesting a slow but continuous production of TDA under neutral conditions. However, less than 0.2 μg/g of TDA was detected as residual TDA in the methylene chloride extracts following up to 60 days at 37 °C. PU foam extracted with methylene chloride under similar conditions showed higher foam weight loss, 4.4 and 5% at 1 and 2 weeks, respectively. The results presented in this study provide further evidence that Microthane undergoes hydrolysis under neutral conditions in aqueous solutions producing TDA and other unknown low molecular weight components and oligomers. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050102
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  • 4
    Electronic Resource
    Electronic Resource
    Chemical and mechanical degradation of UHMWPE: Report of the development of an in vitro test (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 17-21 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Ultra high molecular weight polyethylene (UHMWPE), used in total joint replacement implants, undergoes oxidative degradation due to gamma radiation sterilization and to exposure to oxidizing agents in the body environment. UHMWPE components also experience large stresses both on and near the articulating surface. It is hypothesized that there is a causal relationship between chemical degradation and mechanical loading of UHMWPE joint components. This report describes the development of an in vitro test to examine the combined effects of chemical environment and cyclic loading history on the chemical, physical, and mechanical properties of UHMWPE. The test apparatus consists of modular load trains, in which strings of UHMWPE test specimens can be subjected to cyclic tensile and compression load ranges, while being exposed to either control or degrading environments. Following cyclic loading for specified time intervals, the specimens can be statically loaded to determine the effect of cyclic loading and environment on the monotonic tensile and compressive stress-strain behavior of UHMWPE. To determine the appropriate control and degrading environments, gamma radiation sterilized UHMWPE specimens were maintained (unloaded) for up to 6 months in aqueous environments of distilled water and three concentrations of hydrogen peroxide (0.01, 0.1, and 1.0%) in distilled water at 37°C. Specimens were evaluated with depth from the surface for changes in density. Infrared spectroscopy (IR) analysis was conducted on selected surface sections. No significant changes in density or surface IR spectra occurred for specimens in distilled water as compared with the UHMWPE in the initial radiation sterilized condition. Specimens exposed to hydrogen peroxide solutions demonstrated changes in density and IR spectra consistent with oxidative degradation and comparable to the changes previously observed on retrieved UHMWPE components. Based on these results, distilled water was selected for the control environment. A 0.5% hydrogen peroxide solution was selected for the test environment, to produce moderate changes at a rate compatible with the maximum 12-month time period of the experiment. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050104
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  • 5
    Electronic Resource
    Electronic Resource
    A method for transmission electron microscopy investigation of the osteoblast/hydroxyapatite interface (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 39-45 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Neonatal rat calvaria osteoblasts were cultured on hydroxyapatite (as received or relatively-rough surface and mechanically polished to a 0.3-m̈m finish) and on glass (reference material) in Dulbecco's Modified Eagle Medium supplemented with 10% fetal bovine serum, 50 μg/mL ascorbic acid, and 10 mM β-glycerophosphate under standard, sterile, cell-culture conditions for 1, 3, 7, 14 and 21 days. At the end of the prescribed time periods, the cells were fixed and embedded in resin before removing the material substrates by exposure to acid solutions. Transmission electron microscopic examination of stained, ultrathin sections of the biological structures revealed osteoblast monolayers at 1 day of culture but multilayered cell structures at later time periods (14 and 21 days). The osteoblasts exhibited continuous contact and intimate apposition on polished hydroxyapatite and on glass; in contrast, osteoblasts on as received or rough hydroxyapatite made contact with discrete high points, spanned low regions of the material surface, and did not conform to all substrate contours. An electron dense layer (composed of mucopolysaccharides and proteins) was observed on all substrates tested after 7 days of culture. Collagen fibrils were seen interspersed among the osteoblasts as early as 3 days of culture; at later culture times, (i.e., 21 days) mineralized loci were observed in the extracellular matrix. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050106
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  • 6
    Electronic Resource
    Electronic Resource
    Behaviour of endothelial cells cultured in the presence of polymers impregnated with adsorbable proteins (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 47-50 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The aim of this study is the in vitro evaluation of the functional modifications of human endothelial cells in the presence of Dacron® impregnated with resorbable proteins. For this purpose, human endothelial cells isolated from the umbilical vein have been put in contact for 48 h with knitted Dacron® impregnated with collagen or gelatin and with nonimpregnated knitted Dacron® and double velour Dacron®. As control, endothelial cells cultured in the absence of material were used. After the contact time, cell counts were performed. In addition, the concentrations of two proteins synthesized by endothelium, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1), were evaluated on the supernatants. In the cultures in contact with Dacron® impregnated with collagen or gelatin and in those in contact with knitted Dacron®, we have observed a smaller cell growth than that observed in cultures without materials. The synthesis of t-PA showed some significant variations between the control cultures and those in contact with the materials. PAI-1 production was significantly reduced in the cultures in contact with gelatin impregnated Dacron® and with knitted Dacron®. Double velour Dacron® caused no significant variation in any of the examined parameters. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050107
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  • 7
    Electronic Resource
    Electronic Resource
    A new technique for quantitation of metal particulates and metal reaction products in tissues near implants (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 191-193 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Tissue specimens retrieved from four regions adjacent to hip implants during revision surgery were subjected to a novel treatment to make possible the quantitative separation of residual metal particulates and metal reaction products (metal ions and metal-protein complexes). The tissues were exposed to sodium hypochlorite solution that degraded and solubilized them, liberating metal reaction products and leaving behind metal wear particles, which were separated by centrifugation. Atomic absorption spectrophotometry was used to analyze the concentrations of the separated metal ions and wear particles. Co ion concentrations were 0.05 to 0.9 mM, Cr ion concentrations were 0.04 to 2.1 mM, and Ti ion concentrations were 0.30 to 0.60 mM. The weight of Co metal particles was 0.1 to 4.9 mg/100 mg tissue, of Cr metal particles 0.07 to 2.2 mg/100 mg tissue, and of Ti particles 0.09 to 5.2 mg/100 mg tissue; one black tissue sample contained 3333 mg Ti/100 mg tissue. No correlation was found between the concentrations of these two entities in the samples examined, probably due to the complex and varied processes creating them. The procedures discussed here will result in data that can help elucidate the separate contributions of metal reaction products and metal particulates to implant loosening. © 1994 John Wiley & Sons, Inc.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050303
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  • 8
    Electronic Resource
    Electronic Resource
    Fatigue behavior of a titanium femoral hip prosthesis with proximal sleeve-stem modularity (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 195-201 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Modular hip prostheses are increasing in variety and utilization. Component stability, high endurance limit, and minimal particulate debris generation are critical for long-term clinical success. The purpose of this study was to characterize the fatigue response and evaluate the in vitro potential for component motion and wear of the S-ROMTM, a Ti-6Al-4V hip prosthesis with a modular design based on a Morse taper connection. A fatigue jig was desiged to simulate fixation of the device at the sleeve-bone interface only with distal support mainly against the lateral endosteal cortex. Two series of tests were performed in air at room temperature: one with direct vertical loading (to produce high bending moments in the coronal plane) and one with a compound loading angle directed at 15° out-of-plane (to include torsional physiological loads). Applied loads using a servohydraulic test machine ranged from 5 × BW (body weight) to 9 × BW (1 × BW = 73 kg, ≈ 160 lb) at 10 Hz on an Instron apparatus. No mechanical failures were observed on the 11-mm size stems below 6 × BW for in-plane vertical loading, and at or below 7 × BW for out-of-plane loading. Using displacement monitoring with a sensitivity of 35 μm, no measurable slippage or relative motion was detected between the stem and sleeve when they were properly assembled. Examination of the contact areas with scanning electron microscopy revealed random surface modification (an indication of fretting or burnishing) with occasional evidence of transfer of material between stem and sleeve. At loads under 7 × BW there was no visual evidence of loose wear debris in the presence of gross stability. Overall, the extent of surface change or wear was relatively small in all components tested at physiological load levels. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050304
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  • 9
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994) 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050201
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  • 10
    Electronic Resource
    Electronic Resource
    FEM analysis of stress and deformation in the vicinities of arterial graft anastomosisThis work was performed at the Department of Biomedical Control, Research Institute of Applied Electricity, Hokkaido University, Sapporo, Japan. (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 79-87 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Effects of compliance mismatch at end-to-end artery/graft anastomoses on the distributions of wall stresses and compliance were studied using the finite element method. The canine common carotid artery (CCA), and expanded polytetrafluoro-ethylene (EPTFE) thin-walled graft, and a newly developed polyurethane graft (HS-2) were used as the models for the host artery, stiff graft, and compliant graft, respectively. Mechanical properties of CCA and HS-2 were determined from a pressure-diameter test, those of EPTFE graft were obtained by tensile test. Nonlinear elasticity of CCA and HS-2 was incorporated by iterating a linear FEM analysis: elastic moduli of the vessel walls were changed every 5 mmHg. The results showed that, in the case of the artery/EPTFE anastomosis in which the diameters of the artery and the graft were matched at 0 mmHg, regions of high tensile and shear stresses appeared in the graft near the anastomosis at the intraluminal pressure of 100 mmHg. The stress concentrations were remarkable, even if the diameters were matched at 100 mmHg and the pressure was varied within a physiological range (60-140 mmHg). Moreover, a hypercompliant zone appeared in the arterial wall near the anastomosis in this case. On the other hand, neither high stress concentrations nor hypercompliant zone appeared near the artery/HS-2 anastomosis. Because the mechanical complications at the compliance-mismatched anastomosis might finally result in graft failure and occlusion, it is important to match the compliance of graft to that of natural arteries, particularly to improve the patency of small-calibered arterial grafts. © 1994 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050110
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  • 11
    Electronic Resource
    Electronic Resource
    Technical note. Symmetry of biomechanical properties in canine femora (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 99-101 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050112
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  • 12
    Electronic Resource
    Electronic Resource
    Physical properties of hyaluronic acid and hydroxypropylmethylcellulose in solution: Evaluation of coating ability (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 89-98 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Hyaluronic acid (HA) and hydroxypropylmethylcellulose (HPMC) in buffered saline are “viscoelastics” used in ophthalmic surgery to prevent mechanical damage to delicate eye structures and to form a protective coating over corneal endothelium.HA is a high molecular weight polysaccharide that exhibits decreasing viscosity at increased shear rates. HPMC is a cellulose derivative that exhibits low surface tension. This study examines the physical properties of HA and HPMC solutions and attempts to correlate these properties with the ability of those macromolecules to coat and protect ocular structures.Results presented in this article suggest mixtures of HA and HPMC exhibit low surface tension and ease of aspiration characteristics that are desired in viscoelastic materials. For this reason a blend of these two macromoleculars offers handling advantages over each of these individual macromolecules. © 1994 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050111
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  • 13
    Electronic Resource
    Electronic Resource
    Effects of metallic debris on adult bovine articular chondrocyte metabolism in vitro (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 109-115 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The purpose of this study was to examine the effects of particles, derived from metals commonly used in joint prostheses, on chondrocyte proliferation, metabolism, and morphology in vitro. Chondrocyte viability was influenced by the type and concentration of metal particle added. Cobalt was toxic to chondrocytes at all particle concentrations (0.83-0.000083%, v/v), whereas the chromium, titanium and titanium-aluminum particles only effected chondrocyte viability at high concentrations. The metabolic response of chondrocytes to particulate debris as assessed by caseinase, collagenase, and hexosaminidase activities were variable at low concentrations but were always reduced at high concentrations (0.83% v/v). Prostaglandin E2 levels in the medium showed a steady increase when particle load increased, except in the medium of chondrocytes exposed to titanium-aluminum. Scanning electron microscopy of chondrocytes exposed to titanium showed ruffled cell borders and frequent membrane blebbings. This was in contrast to chondrocytes exposed to cobalt, where the crenated appearance indicated cell death, and titanium-aluminum, where the cells appeared quiescent. These findings show that metal particles alter chondrocyte viability and metabolism and suggest that particulate debris may influence the integrity and stability of articular cartilage following hemiarthroplasty. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050203
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  • 14
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994) 
    Details
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040101
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  • 15
    Electronic Resource
    Electronic Resource
    Encapsulated alkaline earth metallocenes. 3: Structural influences on phase transformations alkaline earth complexes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 1-8 
    Details
    ISSN: 1057-9257
    Keywords: Alkaline earth ; Calcium ; Ligand flexibility ; Magnesium ; Melting point ; Metallocene ; Phase transformation ; Volatility ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Reaction of two equivalents of KCp3i (Cp3i ≡ 1,2,4-(i-Pr)3C5H2) with MgBr2 in Et2O produces the base-free metallocene (Cp3i)2Mg in high yield; the similarly prepared organocalcium complex (Cp3i)2Ca, although initally isolated as an oil, forms a crystalline solid on standing for several months. Crystals of (Cp3i)2 CA are tetragonal, space group P42/n, with a = 18.147(4), c = 15.996(4) Å, Å and Dcalc = 1.066 g cm-3 for Z = 8. Lease-squares refinement based on 2044 reflections led to a final R-value of 0.072. The complex possesses a metallocene geometry that is slightly bent; the average Ca-C distance is 2.62(2) Å and the right centroid-Ca-ring centroid angle is 169.7°. Comparison of these complexes with previously reported alkaline earth metallocenes suggests that the volatility of the metallocenses depends primarily on the degree of aggregation in the solid state, whereas the melting point of the nonomeric compounds varies with the asymmetry and ligan flexibility in the complex.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860040102
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  • 16
    Electronic Resource
    Electronic Resource
    Langmuir-Blodgett films of indandione-l,3 pyridinium betaine. II: Molecular structure and properties of monolayers; simulation and optical absorption data (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 27-41 
    Details
    ISSN: 1057-9257
    Keywords: Amphiphilic indandione-1,3 pyridinium betaine derivatives ; Langmuir-Blodgett monolayers ; Monolayer spectral characteristics ; Simulation of molecular structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The molecular structure and optical properties of a monolayer at the air/water interface of novel amphiphilic derivatives of indandione-1,3 pyridinium betaine (IPB) with different lengths of the aliphatic tail, namely C1lIPB and C17IPB, have been studied using optical absorption techniques and computer simulation approaches.The compression π-A isotherm of the C17IPB monolayer and computer simulation of its molecular structure show that there may exist two energetically stable molecular configurations, one with antiparallel orientation of the dipole moments of the C17IP ‘heads’ in the low-pressure region at π = 5-32 mN m-1 and the second (after a distinct phase transition at π = 33 mN m-1) with parallel orientation of the dipoles, with different tilt angles and areas per molecule. For C11IPB only the first structural phase is observable.The compression-induced changes in spectral characteristics of the two structural phases go in diametrically opposite directions. In the low-pressure phase compression induces a red shift and an increase in intensity of the S1 absorption band, while in the high pressure phase a blue shift and a decrease in the intensity of this band are observed. These spectral changes correlate reproducibly with the compression π-A isotherms. Measurements of absorption dichroism confirm the change in the tilt angle at the phase transition pressure. The compression-induced spectral changes have been substantiated by the results of quantum chemical calculations.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040105
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  • 17
    Electronic Resource
    Electronic Resource
    Electron beam and X-ray resists (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 139-153 
    Details
    ISSN: 1057-9257
    Keywords: X-ray resists ; Electron beam ; Acrylate and methacrylate polymers ; Polysulphones ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The optimisation of the lithographic performance of negative-working electron beam resists is developed through consideration of the radiation chemistry of crosslinking of representative materials, typically epoxy-functionalised polymers and polystyrene and its derivatives. Similarly, the lithographic behaviour of positive-working systems based on radiation-induced chain scission reactions is discussed with reference to acrylate and methacrylate polymers and polysulphones. The difficulties encountered in devising desirable working systems based on novolacs are considered and contrasted with the promise offered by recent developments arising from the extension of chemical amplification techniques to the electron beam lithographic domain.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860040208
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  • 18
    Electronic Resource
    Electronic Resource
    Molecular image-processing devices based on chemical reaction systems. I: General principles for implementation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 179-190 
    Details
    ISSN: 1057-9257
    Keywords: Molecular computing ; Molecular neurocomputer ; Molecular image-processing devices ; Computational complexity ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Potentialities for implementing simple neural information-processing devices based on chemical and biochemical dynamical media are discussed. Pilot ‘hardware’ models of neural molecualr devices that able to perform image-processing operations were constructed.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860040302
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  • 19
    Electronic Resource
    Electronic Resource
    Artifice and artefacts, 100 essays in materials science. Robert W. Cahn. Institute of Physics Publishing, Bristol, ISBN 0 7503 0152 X xiii + 365 pp. £19.95 or $39.90 (paperback) (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 233-233 
    Details
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040307
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  • 20
    Electronic Resource
    Electronic Resource
    Dynamics of impurity-related optical switching in CdS near the band edge (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 41-49 
    Details
    ISSN: 1057-9257
    Keywords: Front optical switching ; Optical non-linearities impurities ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: We present a dynamic theory related to experiments on the induced transmission of doped CdS crystals under pulsed laser excitation at 2 K at frequencies just below the band gap. Numerical simulations of the optical switching front which describes the non-linear spatio-temporal dynamics of the switching process from low to high transmittivity and back are performed for two different two-level models. These are associated with two different bleaching mechanisms of the acceptor-conduction band transition.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030107
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    Anisotropy of dissolution and microrelief of II-VI semiconductor compound surfaces (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 67-72 
    Details
    ISSN: 1057-9257
    Keywords: Anisotropy ; Dissolution ; Microrelief ; II-VI semiconductor compounds ; Light figures ; Etching ; Electron beam lasers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The shape, crystallographic orientation and size of microrelief elements of various surfaces of CdS, ZnSe and ZnO monocrystals after chemical etching have been studied. When illuminated with a focused laser beam, the microrelief creates a symmetric light pattern, or light figures, on the opposite surface whose shape corresponds to the crystal symmetry.The effects of the dissoltion rate and etching time on the form, size and angles of the microrelief elements in the temperature interval from 263 to 333 K were investigated. During etching, laser light was also used to convert the process of selective etching into a polishing process. To elucidate the relationship between the crystallographic orientation of the microrelief elements and the dissolution anisotropy, mean etching rates were determined and polar diagrams of resistance to dissolution were constructed for {1120} and {0001} by the Gross method. The relation between the kinetics of dissolution and the structure of the chemical bonds is discussed.The light figures formed by the surface microrelief enabled us to carry out the approximate orientation of semiconductor planes and solid samples. In the early stages of dissolution one may determine the density and distribution of the microscopic etch pits. The microrelief created on the side surfaces and the ‘fully reflected’ mirrors of II-VI semiconductor lasers pumped by electron beam or optical radiation promote the multiple enhancement of laser power and efficiency.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030110
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    Electronic Resource
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    Origin of the stokes shift in semiconductor quantum wells (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 95-101 
    Details
    ISSN: 1057-9257
    Keywords: Stokes shift ; Quantum wells ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Excitonic energy levels have been calculated in CdTe quantum wells with Cd1-xMnxTe barriers. It has been shown that the introduction of small-scale (relative to the exciton Bohr radius) interface disorder, which either preserves or breaks the inversion symmetry, can produce appreciable Stokes shifts between optical absorption and emission and that the associated line-widths can remain narrow. A criterion for the existence of high-quality interfaces, based on optical spectra, is described.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030114
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    Photoluminescence and efficiency of Ce3+ in SrS powders (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 131-136 
    Details
    ISSN: 1057-9257
    Keywords: II-VI compound ; SrS : Ce ; Photoluminescence ; Concentration quenching ; Phosphorescence ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The luminescence efficiency of SrS: Ce powders in the doping range from 0.01 to 1.0 at.% was investigated by photoluminescence decay studies. The radiative decay time of Ce3+ in SrS was determined to be 27 ns. The onset of concentration quenching at concentrations higher than about 0.7 at.% has been obtained. The photoluminescence spectrum of Ce3+ exhibits two emission bands as a consequence of the ground state splitting. The Huang-Rhys factor of the 5d-4f transition was estimated to be about 6. The inhomogeneous broadening of the emission band of samples with higher doping level has been investigated by site-selective and time-resolved spectroscopy.
    Additional Material: 9 Ill.
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    Inorganic materials. D. W. Bruce and D. O'Hare. Wiley, Chichester, 1992, ISBN 0 471 928895 £58.00 (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 233-234 
    Details
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040308
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    Announcement (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 239-239 
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    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040310
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    Guest Editorial (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 241-242 
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    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040402
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    Peculiarities of the quantisation of the energy spectrum of gapless semiconductors in a magnetic field under space confinement (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 57-65 
    Details
    ISSN: 1057-9257
    Keywords: Energy spectrum ; 2D systems ; Gapless semiconductor ; Magnetic field ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: An exact solution for the zero boundary condition of the problem of carriers in spatially confined gapless semiconductors in a magnetic field is presented. Three cases are analysed: (i) the semiconductor occupies a half-space and the magnetic field orientatin is H ⊥ n (n is the surface normal); (ii) and (iii) a film of a gapless semiconductor at two orientations of the magnetic field, i.e. H ⊥ n and H | n respectively. It is shown that since the energy spectrum of gapless semiconductors is formed by strong relativistic spin-orbit interaction, significant peculiarities of the quantisation of the electron energy spectrum occur in all cases considered. Experiments to check the results obtained are discussed.
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    Novolac-based resists (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 75-82 
    Details
    ISSN: 1057-9257
    Keywords: Novolac resins ; Positive-working resists ; DNQs ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The performance of novolac-diazonaphthoquinone-based positive-working resists is discussed in terms of the molecular weight distributions and microstructures of the novolac resins and the structural variations in the photoactive dissolution inhibitor. Modelling studies leading to recent improvements allosing the delineation of 0.35 μm line and space pattens by ensuring a focal depth of 105 μm are outlined. Consideration is also given to the new problems such as pivotal shift and halation that arise in the application of high-resolution photolithography using novolac-diazonaphthoquinone resists.
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    p-Doping of GaAs and AlGaAs using the triethylamine adduct of dimethylzinc (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 343-347 
    Details
    ISSN: 1057-9257
    Keywords: Dimethyzinc ; Adduct ; MOVPE ; GaAs (p-doping) ; AlGaAs (p-doping) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The adduct between dimethylzinc and triethylamine has been used as a p-dopant source in the growth of GaAs and Al0.3Ga0.7As alloys by metalorganic vapour phase epitaxy (MOVPE). The dopling efficiency of this adduct in these alloys and in InP is lower than that of dimethyl zinc.
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    Electron-beam-pumped laser emitters with microrelief mirrors based on II-VI semiconductorsPresented at European II-VI Workshop, Aachen, 1993. (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 365-371 
    Details
    ISSN: 1057-9257
    Keywords: II-VI semiconductor ; Laser ; Generation ; Longitudinal electron beam pumping ; Microrelief ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The power characteristics of electron-beam-pumped emitters based on II-VI compounds have been stukdied. The use of a microrelief with direction-selective reflective properties instead of a totally reflecting miror has made it possible to provide effective sukppression of closed non-characteristics and efficiency of lasers and to make them suitable for obtaining generation with high efficiency in a number of media, in particular YAG:Nd3+, KGW:Nd3+ and Lif:F2+ (OH), at room temperature.
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    Crystallographic orientation and light emission of streamer discharges in II-VI semiconductorsEuropean II-VI Workshop, Aachen, 1993. (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 373-380 
    Details
    ISSN: 1057-9257
    Keywords: II-VI semiconductor ; Laser ; Streamer ; Electric discharge ; Luminescence ; Generation ; Crystallographic orientation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Some results of Investigations on the crystallographic orientation, luminescence and stimulated emission of streamer discharges in monocrystals of hexagonal CdS, CdSe and ZnO and cubic Znsand Snseare presented.
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    In situ optical monitoring of the movpe growth of ZnSe on GaAs (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 401-405 
    Details
    ISSN: 1057-9257
    Keywords: MOVPE ; ZnSe ; Growth mechanism ; Surface chemistry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: In situ optical reflection measurement was employed to study surface processes during the MOVPE growth of ZnSe films under an alternate supply of diethylzinc (DEZn) and dimethylselenide (DMSe) using H2 and/or N2 as carrier gases. We have found that the time-dependent reflection signal exhibits a unique saw-toothed pattern during the DEZn supply, which is attributed to the adsorption and structural change of the DEZn. In contrast, the influence of DMSe on the time-dependent signal appears to be rather marginal. A growth mechanism is proposed based on these experimental results, through which the important role of ambient hydrogen is discussed.
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    Optically stimulated intersubband absorption in undoped amorphous Si/SiO2 qiantum well (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 417-421 
    Details
    ISSN: 1057-9257
    Keywords: Amorphous quantum wells ; Intersubband transitions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Intersubband absorption has been observed in undoped amorphous multiple-quantum-well (MQW) strucctures under interband excitation. The transitions take place between the first and second subbands of the conduction band and involve non-equilibrium electrons excited into the first subband by optical pumping. The absorption band FWHM of 0.1 eV is much larger than for crystalline MQWs, a fact which reflects the relaxation of the electron momentum conservation in the QW plane. The high joint density of states and oscillator strength for the intersubband transitions in amorphous QWs allow one to observe the absorption at low electron concentrations (Ne ≈ 1013 cm-3) in the ground conduction subband.
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    Identification of the volatile decomposition products produced in the deposition of (Hg,Cd)Te by MOVPE (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 151-161 
    Details
    ISSN: 1057-9257
    Keywords: MOVPE ; (Hg, Cd)Te ; Decomposition products ; GC-MS ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The pyrolysis reactions of di-isopropyl telluride and dimethyl cadmium, both alone and in combination and with and without mercury, have been studied using the technique of gas chromatography-mass spectrometry (GC-MS). For example, when mercury and dimethyl cadmium are mixed in hydrogen at the growth temperature (370°C), the volatile products observed are methane, ethane and dimethyl mercury. In contrast, when di-isopropyl tellurideis substituted for the cadmium precursor in this reaction, the products observed are propane, propene and 2,3-dimethylbutane with no volatile mercury-containing compounds. Heating the two organometallic precursors together at the growth temperature in the absence of mercury gives products expected from the pyrolysis of each one alone plus a number of interaction products such as 2-methylpropane. The results of these studies will be presented, a mechanism for the reactions proposed and the implications for MOVPE growth discussed.
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    Radiative efficiencies and deep levels in zinc selenide (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 199-202 
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    ISSN: 1057-9257
    Keywords: Zinc selenide ; Luminescence ; Deep levels ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Although zinc selenide and related materials are promising for blue light-emitting diodes and lasers, present performance is unsatisfactory. The blue radiative efficiency at room temperature is low and the decay time of luminescence is correspondingly short. It is argued that the problem is non-radiative recombination by the Hall-Shockley-Read mechanism at deep levels and that the concentration of these levels must be high. Experimental evidence for the existence of such levels is presented. Characterisation and control of deep levels will be essential for progress in this area.
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    A comparison of the diffusion of copper, gallium and cadmium in cadmium telluride (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 209-215 
    Details
    ISSN: 1057-9257
    Keywords: Diffusion ; Cadmium telluride ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The rates of diffusion of both Ga and Cu in CdTe have been measured over the temperature ranges 350-820 and 200-400°C respectively and the results are compared with the self-diffusion of Cd (350-920°C).In the case of the Cd self-diffusion the Arrhenius graph showed two active diffusion mechanisms, one dominating above 500°C and the other below. It suggested that in the temperature range 500-800°C the main defect responsible for diffusion was Cdi-, with a significant contribution at lower temperatures from the associated defect of the form (CdiVcd)x Below 500°C another mechanism predominated which was possibly due to residual impurities.The results for the diffusions were in close agreement with those obtained by other workers. The Ga diffusions showed a complex behaviour which suggested that two mechanisms were active simultaneously, one independent of Cd partial pressure and the other decreasing with increasing Cd partial pressure.It was concluded that CdTe would be suitable as a diffusion barrier to protect HgxCd1 - xTe devices from Ga contamination from GaAs substrates but would not be efficient at reducing Cu contamination from the substrate in the device.
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    Comparison of two approaches to forced convection in crystal growth of II-VI compounds by THM (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 233-238 
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    ISSN: 1057-9257
    Keywords: Solution growth ; THM ; HgCdTe ; CdZnTe ; Forced convection ; ACRT ; Solvent inclusions ; IR microscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Hg1 - xCdxTe and Cd1 - xZnxTe single crystals were grown by the tracwelling heater method (THM), applying two different techniques of artificially stirring the solution zone. Accelerated crucible rotation (ACRT) was used in a vertical growth arrangement and compared a technique with constant rotation around the horizontal axis of the ampoule. The dominant hydrodynamic mechanisms of noth methods are discribed by the rotating disc model and are suggested to be almost identical with respect to the growth conditions at the interface. Convective flow is effectively enhanced adhacent to the growing crystal, where the matter transport is regarded as the rate-limiting step of solution growth. Inclusion density analysis by IR microscopy was used to characterise the crystals of Cd1 - xZnxTe grown at different rates. It was shown that forced convection allows an increase in the crystal growth rate from a few mm day-1 with ACRT or horizontally rotating THM.
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    Analysis of photoinduced current transient spectroscopy (PICTS) data by a regularisation method: Application of compensation defects in CdTe (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 269-274 
    Details
    ISSN: 1057-9257
    Keywords: Compensation defects ; PICTS ; CdTe ; Tikhonov regularisation ; III-posed problems ; Deep levels ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: A detailed analysis of photoinduced current transients of differntly grown CdTe:Cl samples was performed in the 100-130 K range in order to investigate the influence of the different growth techniques (sublimation, Bridgman method and travelling heater method (THM)) on the compensation defects. The transients were evaluated using a regularisation method (fast Tikhonov regularisation) as implimented in the program FTIKREG. The advantages of the regularisation method in comparison with the customary two-gate technique are demonstrated by the analysis of simulated data. It can be shown that the different growth techniques have only one level in common. Furthermore, the superposition of different traps can lead to wrong results using the conventional two-gate technigque. The temperature dependence of the relaxation times is evaluated and the corresponding trap parameters are determined.
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    Liquid crystalline hydrogen-bonded complexes formed between alkoxystibazoles and phenols (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 273-276 
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    ISSN: 1057-9257
    Keywords: Liquid crystals ; Hydrogen bonding ; Phenols Stilbazoles ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Mesomorphic materials formed by hydrogen bonding between 4-alkoxystillbazoles and some phenols are described.
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    Isomorphous mixing of mesogenic anions and uncharged analogues in organised poly(ehtylene oxide)-alkali salt complexes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 265-271 
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    ISSN: 1057-9257
    Keywords: Poly(ethy1ene oxide)-salt complexes ; Anionic mesogens ; Uncharged mesogens ; Isomorphous mixture ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The preparation and characterisation of novel ionic polymer liquid crystal complexes of poly(ethylene oxide)-Na+ with mesogenic anions and their uncharged structural analogues in homogeneous mixtures are described. The systems discused most fully are the anion of the phenolic mesogen 4-n-hexyloxybenzylidene-4-hydroxy aniline (1) with its uncharged analogue 4-n-hexyloxybenzylidene aniline (1a) and the anion of 5-(4-n-octyloxy-2,3-dicyanophenyleneoxycarbonyl)benzimidazo-le (2) and its uncharged analogue 4-octyloxy-2,3-dicyanophenyloxybenzoyl (2). Differential scanning calorimetry, wide angle x-ray diffraction and polarised light microscopy show that PEO-Na1/1a and PEO-Na2/2a are homogeneous mesogenic phases when Na1 or Na2 are present at 50% or less of the stoichiometric composition in complexes (EO : salt = 3 : 1) and the shortfall is made up from 1a or 2a uncharged analogues of 1a and related systems substituted by methoxy rather than hydrogen do not form homogeneous mixtures.
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    Macroscopic non-linearities of some stilbazolium derivatives and the calculatium derivatives and the calculation of their molecular hyperpolarisability (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 293-301 
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    ISSN: 1057-9257
    Keywords: Non-linear optics ; stilbazolium salts ; MOPAC calculations ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The synthesis of some optically non-linear stilbazolium salts is described. Since their solid state non-linearities were small, MOPAC5 was used to compare their relative molecular non-linearities.
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    Oxide removal from the GaSb surface and fabrication of MBE GaSb photodiodes and Au-GaSb schottky diodes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 319-325 
    Details
    ISSN: 1057-9257
    Keywords: GaSb ; Photodiodes ; Schottky diodes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Oxide removal from GaSb surfaces by several wet chemical treatments and subsequent thermal annealing was investigated. Preferable wet chemical treatments by which surface oxides could be removed effectively at room temperature were evaluated in the experiments. This method can be effectively applied to fabrication processing of MBE GaSb photodoides and Au-GaSb Schottky doides. Low-reverse-leakage GaSb photodiodes and near ideal Au-GaSb Schottky diodes were thus obtianed.
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    MOVPE growth and characterization of ZnSxSe1 - x/ZnSe quantum wells (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 191-198 
    Details
    ISSN: 1057-9257
    Keywords: ZnSe ; ZnSSe ; GaAs substrate ; MOVPE ; Photoluminescence ; Quantum well ; Interface properties ; Growth interruption ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: In this work we report on ZnSxSe1 - x/ZnSe quantum wells grown by atmospheric pressure MOVPE on GaAs substrates. Diethylznc (DEZn), diethylselenium (DESe), diethylsulphur (DES) and H2S were used as source materials. Binary quantum wells with ZnSe or ZnS as barrier were usually grown in sets of 10 pairs on a 0.5 μm ZnSe or ZnS buffer, respectively. QWs with different well thicknesses (1-4 nm) show a typical shift to higher energies with decreasing well thickness and also a large decrease in PL intensity with increasing well thickness. Owing to the onset of relaxation above 5 nm well thickness, no PL emission could be observed. QWs of the same thickness but grown at different temperatures (420-520°C) show a broadened line shape with decreasing growth temperature. Growth interruption (3-50 s) also causes a broadening of the PL emission with decreasing interruption time. This is caused by interface reconstruction at higher growth temperatures and longer growth interruption. A ZnS buffer of 0.5 μm improves the PL line shape compared with a ZnSe buffer.ZnSxSe1 - x/ZnSe single and multiple QWs (Lz = 1-4 nm) were grown to reduce the strain in the structures. A typical quantum confinement energy shift of 160 meV for the 1 nm well can be observed in ZnS0.68Se0.32/ZnSe QWs. In comparison with the binary QWs, the FWHM could be reduced by about a factor of two to 34 meV. This improvement was obtained by an optimisation of the switching process to prevent the desorption of sulphur from the ZnSSe during the growth interruption.
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    Langmuir-blodgett films of stilbazole complexes of iridium(I) and rhodium(I) (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 243-251 
    Details
    ISSN: 1057-9257
    Keywords: Langmuir-Blodgett film ; Stilbazole ; Metal complex Iridium ; Rhodium Pyroelectricity ; Alternate layer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Complexes of 4-alkoxystilbazoles with iridium and rhodium form stable Langmuir layers at the air-water interface even when the alkoxy chain is relatively short (C5-C12). The surface pressure-area isotherms indicate that condensed molecular monolayers are obtained. The area per molecule of each compound in its monolayer form is typically 0.60 nm2, which agrees well with the cross-sectional area of the [Ir(CO)2CI] or [Rh(CO)2CI] head group predicated using molecular models. This suggests that the molecules are oriented with the metal moiety close to the water surface and their alkoxystilbazole ‘rod’ protruding from the plane of the water surface. Such floating monolayers have been transferred on to solid substrates such as glass, aluminium (AI2O3/AI/Glass) and silicon (SiO2/Si) at relatively high speed (10 mm min -1) to form Y-type LB assemblies. The UV-Visible absorption properties of these materials in solution and LB film form have been studied. LB films of these complexes yield bathochromically shifted spectra relative to the LB film spectrum of the uncomplexed stilbazole. Additionally, these spectra are often broader and hypsochromically shifted relative to their corresponding solution spectra as a result of the close molecular packing within the LB film and the associated dipole-dipole interactions.The electrically polar nature of the molecules described in this paper suggest that they may be suitable candidates for new pyroelectric materials. Thus the pyroelectric coefficient (the rate of change of electric polarisation with respect to temperature) has been measured for a polar multilayer LB film containing an iridium complex. A pyroelectric coefficient of 3.5 μCm-2K-1 (at 30 °C) has been measured, which is one of the highest reported valued for an LB film. Additionally, a low dielectric loss of around 0.01 has been found over the frequency range 50 Hz-1 kHz, indicating that such LB films may be usfeul materials for pyroelectric sensors.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994) 
    Details
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040501
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    Foreword (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 1-1 
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    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860030102
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    Mixed alkyl zinc or cadmium complexes with dialkyl thio- or selenocarbamates: Precursors for cadmium chalcogenides (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 171-175 
    Details
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: A series of new compounds [RME2CNR′2]2 (R and R′ are various alkyl groups, e.g. M ≡ Zn or Cd, R ≡ Me, R′ ≡ Et) have been synthesised and characterised. The compounds can be used as single molecular precursors for the deposition of the corresponding binary chalcogenides. In the present paper the range of compounds synthesised and their uses are reviewed. Preliminary observations on the deposition of thin films on glass and GaAs(100) substrates are reported.
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    Effects of rapid thermal annealing on the electrical properties of Hg1 - xCdxTe bulk crystals (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 177-182 
    Details
    ISSN: 1057-9257
    Keywords: RTA ; Mercury Cadmium ; Telluride ; Hall characterization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: This paper reports the change in the bulk transport properties of p-type MCT samples induced by a rapid thermal annealing (RTA) process. This change is produced homogeneously within the crystal without interchange of mercury with the surrounding atmosphere. The carrier concentration varies towards an equilibrium value that depends only on the annealing temperature. For the material and temperatures investigated (250-420°C) the equilibrium carrier concentration depends exponentially on the inverse of the temperature, its value ranges between 1 × 1017 and 4 × 1017 cm-3. The time needed to reach equilibrium is a function of the temperature, varying from 10 s at 420°C to 200 s at 250°C. The hole mobility is also affected by the RTA process, its evolution being a function of the process temperature and time. A model is proposed to explain these modifications based on a reaction of generation-annhilitation of mercury vacancies and interstitials that would take place within the crystal with no external interaction.
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    Effect of hydroxyapatite coating on bone growth into porous titanium alloy implants under loaded conditions (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 23-37 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Titanium alloy tibial segmented defect repair devices whose stems were coated with two layers of titanium alloy beads (Ti-6A1-4V, bead diameter c. 750 μm) were implanted in six beagle dogs. In four of the animals stems had been plasma-sprayed with hydroxyapatite (HA); the other two animals received devices with uncoated stems. Devices intended for 6-month and 3-month evaluation were implanted in right and left tibiae, respectively. Because the amount of bone ingrowth into pore spaces was greater in cortical bone than in cancellous bone, stems were more stable and firmer in the cortical bone. In stems coated with HA, new bone tissue came into contact with the surface of beads in the superficial layer of the stem faster than in stems not so coated. Furthermore, new bone tissue entered into pore spaces in these stems earlier, in larger amounts, and reached more deeply, binding directly to the beads. Rate and quality of bone ingrowth did not differ between the 3-month and 6-month tibiae; in other words, optimal bone ingrowth was attained within 3 months postimplantation. © 1994 John Wiley & Sons, Inc.
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    Evaluation of absorbable poly(ortho esters) for use in surgical implants (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 51-64 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Recent reports describe an unfavorable noninfective inflammatory response to acidic degradation products in clinical applications of bone fixation devices fabricated from bulk hydrolyzing polyglycolides and polylactides (PGA and PLA). The work described here suggests that poly(ortho esters) (POEs) offer an alternative. By comparison, hydrophobic POEs degrade predominately via surface hydrolysis, yielding first a combination of nonacidic degradation products, followed by alcoholic and acidic products gradually over time. POE specimens proved acutely nontoxic in United States Pharmacopeia tests of cellular, intracutaneous, systemic, and intramuscular implant toxicity.Hot-molded specimens degraded slowly in saline, retaining 92% initial stiffness (1.6 GPa flexion) and retaining 80% initial strength (66 MPa flexion) in 12 weeks. Degradation was almost unaffected by decreasing saline pH from 7.4 to 5.0. This demonstrated the relative hydrophobicity of POEs, since incorporation of small amounts of acid within the polymer markedly increases the degradation rate. Degradation rates were increased substantially by dynamic mechanical loading in saline. This may be true for other degradable polymers also, but no data could be found in the literature. Presumably, tensile loading opens microcracks, allowing water to enter.Solvent cast POE films were strong in tension (30 + MPa tensile yield) and reasonably tough (12-15% elongation to yield). Higher molecular weight films (41-67 kDa) showed no degradation in mechanical properties after 31 days in physiological buffer at body temperature. A 27-kDa film offered similar initial strength and stiffness but began showing mechanical degradation at 31 days. The films showed a decrease in weight with exposure time but no change in either molecular weight or water absorption at 31 days, further supporting the observation that POE degrades by surface hydrolysis rather than by bulk hydrolysis. © 1994 John Wiley & Sons, Inc.
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    Phosphonated polyurethanes that resist calcification (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 65-77 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Cardiovascular implant mineralization involving bioprosthetic materials, such as glutaraldehyde cross linked porcine aortic valves or synthetic materials such as polyurethanes, is an important problem that frequently leads to clinical failure of bioprosthetic heart valves, and complicates long-term experimental artificial heart device implants. Novel, proprietary, calcification resistant polyetherurethanes (PEU) as an alternative to bioprosthetic materials were the subject of these investigations. A series of PEU was derivatized through a proprietary reaction mechanism to achieve covalent binding of 100 to 500 nM/mg of bisphosphonate (2-hydroxyethane bisphosphonic acid, HEBP). The stability of HEBP (physically dispersed or covalently bound) verified by studying the release kinetics in physiological buffer (pH 7.4) at 37°C, demonstrated the covalent binding reaction to be stable, efficient, and permanent. Surface (FTIR-ATR, ESCA, SEM/EDX) and bulk (solubility, GPC) properties demonstrated that the covalent binding of HEBP occurs in the soft segment of the PEU, reduces surface degradation, and does not affect the original material properties of the PEU (prior to derivatization). In vitro calcium diffusion of the derivatized PEU showed a decrease in calcium permeation as the concentration of HEBP covalent binding was increased. In vivo properties of underivatized and derivatized PEU (containing 100 nM of covalently bound HEBP) were studied with rat subdermal implants for 60 days. Explants demonstrated calcification resistance due to the covalently bound HEBP without any side effects. It is concluded that a PEU containing HEBP might serve as a calcification resistant candidate material for the fabrication of a heart valve prosthesis and other implantable devices. © 1994 John Wiley & Sons, Inc.
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    Chemical stress relaxation of polyglycolic acid suture (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 215-220 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Chemical stress relaxation methods are employed to study chemical and mechanical factors influencing the degradation of uncoated polyglycolic acid (PG) sutures. Specially constructed instrumentation is used to study the kinetics of the load bearing capability of PG (DexonTM) 3-0 sutures in hydrolytic solution. The effects of pH, temperature, strain rate, and initial load on the rate of chemical stress relaxation are presented. Data show how mechanical factors such as the rate of loading (related to the speed of knot tying), as well as the final tension, are related to the rate of structural degradation. Maximum stability is observed at approximately 40°C, with slower degradation both above and below this point. Results show that the slower and tighter the suture is pulled, the greater its ability to sustain tensile loads during hydrolysis. © 1994 John Wiley & Sons, Inc.
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    Evaluation of a new absorbable lactomer® subcuticular staple (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 221-226 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The most recent advance in skin stapling is the Auto Suture® SQS®-20 disposable stapler. It approximates and everts wound edges, placing one synthetic absorbable pin in the dermis each time the instrument handle is activated. Staple wound closure was accomplished four times faster than sutural closure of the dermis. Wounds with staple pin closure exhibit superior resistance to infection than wounds approximated by dermal sutures. Although sutures provide more immediate wound security, as measured by wound breaking strength, than dermal pins, the breaking strength of wounds subjected to either dermal pins or dermal sutures were not significantly different 14 days after wounding. © 1994 John Wiley & Sons, Inc.
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    Incidence of infection and analysis of contributing factors in revision joint arthroplasty over a two-year period (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 103-108 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study examined the incidence of infection and the contributing factors in 166 patients undergoing total joint revision surgery. Of these 32 (19%) had organisms grown from material taken at the local site at the time of revision surgery. Six of the culture-negative patients were clinically suspected of having an infection. With the inclusion of these six, the total incidence of infection in these revision patients was 23%. This is not the incidence of infection in total joint surgery. This is the incidence of infection in patients undergoing revision surgery for whatever reason. The cause of infection in 53% of the cases was either Staphylococcus aureus or coagulase-negative Staphylococci. The Gram-negative bacteria were implicated in only five (15%) of the cases. Many of these infections (31%) were in patients who had had the implant for greater than 7 years. Only 15% of the infections were in patients who had the implant for less than 6 months with an additional 9% being revised in the first year. There were no clinical symptoms or underlying conditions, including allergy, that distinguished the infected from the noninfected group. The infection rate was somewhat higher with the cobalt chromium alloys, somewhat less in the uncemented devices, and somewhat higher in the patients with total knee replacements than those with total hip replacements. The histopathologic analysis revealed that the presence of polymorphonuclear leukocytes (PMNS) was correlated with infection, but most patients with infection had lymphocytes rather than PMNS indicative of a chronic infection. Thus the diagnosis of infection on the basis of histopathology needs to be carefully evaluated. The presence of PMNS is diagnostic for infection, but has a high number of false negatives. The histopathologic data and the data on implantation time indicate that most of these infections are chronic infections. © 1994 John Wiley & Sons, Inc.
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    Effects of intermittent micromotion versus polymer particles on tissue ingrowth: Experiment using a micromotion chamber implanted in rabbits (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 117-123 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Both micromotion and particulate debris have been implicated in the process of aseptic loosening of joint arthroplasties and the failure of bone ingrowth into porous coated prostheses. In the present study, we compare the histological and histomorphometric results of tissue ingrowth into titanium chambers in the presence of interfacial micromotion versus phagocytosable particles of two polymers used in orthopedic surgery. The micromotion chamber, having a 1 × 1 × 5 mm transverse canal for tissue ingrowth was implanted into the proximal right tibia of five mature male New Zealand white rabbits. In the first series, the chambers were manipulated at 40 cycles per day (cpd) at 1 Hz, using an amplitude of 0.5 mm. The tissue within the chamber was harvested after 3 weeks. In the following series, fabricated particles of bone cement or highdensity polyethylene (HDPE) were mixed with the carrier, 1% sodium hyaluronate (Healon) to obtain a concentration of 108 particles/mL; this solution was implanted in the canal of the chamber but micromotion was not instituted. Histological sections from control, nonmoved chambers, or those implanted with the carrier Healon alone contained extensive trabecular and woven bone embedded in a fibrovascular stroma. The application of 40 cpd resulted in less formation of bone and more fibrous tissue within the chamber. The sections containing particles of bone cement were infiltrated by numerous foamy, mononuclear, and multinuclear histiocytes. HDPE particles were associated with more fibrosis and a less aggressive foreign body response compared to cement particles. Chambers manipulated at 40 cpd and those containing cement or HDPE particles contained less bone compared to nonmoved chambers or those containing Healon alone. Despite evoking different histological reactions, the presence of micromotion or polymer particles appears to inhibit the formation of bone in this experimental model. © 1994 John Wiley & Sons, Inc.
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    Materials and design concepts for an intervertebral disc spacer. I. Fiber-reinforced composite design (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 125-132 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The intervertebral disc is a complex joint anatomically and functionally. It may be displaced or damaged due to trauma or a disease process. To alleviate this condition, it may be necessary to remove the involved disc surgically and fuse the two adjacent vertebrae. Fusion is one option; however, replacing the damaged disc (or part thereof) with a suitable synthetic equivalent to allow near normal joint motion is more desirable. Unfortunately, the complex mechanical properties of the lumbar disc cannot be duplicated with homogeneous synthetic materials (polymers). To overcome this fundamental problem we have developed rational designs utilizing biocompatible thermoplastic elastomers of various stiffnesses (durometers) with and without fiber reinforcements. Our design consisted of three components analogous to the natural end plates, annulus, and nucleus. In this study only the fiber-reinforced design is considered. The variables examined in the present study included orientation of the fiber layers, number of fiber layers, and order of the reinforcing layers. The results of mechanical testing of the fiber reinforced disc spacer indicate that a range of compressive and torsional properties can be achieved. The results further demonstrate that properly developed, this design results in properties similar to the natural disc. Designs developed provided adequate compression and compression torsion properties for a synthetic spine disc spacer. © 1994 John Wiley & Sons, Inc.
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    Processing and characterization of absorbable polylactide polymers for use in surgical implants (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 133-140 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Absorbable fibers of linear poly-α-hydroxy acids have been used successfully in providing temporary scaffolds for tissue regeneration. In some surgical applications, degradation rates for poly(glycolide) (PGA) are too high, but implants of poly(L-lactide) (PLLA) fibers may degrade too slowly for optimal function. Polymers produced by copolymerization of L-lactide with varying amounts of D-lactide may offer an alternative choice for absorbable fiber based implants. Poly(L/D-lactide) stereocopolymers with L/D lactide molar ratios of 95/5, 90/10, and 85/15 were considered. Melt-spun/hot-drawn fibers with L/D molar ratios of 90/10 and 85/15 and draw ratios ranging from 3.0 to 8.9 were further evaluated by mechanical testing, differential scanning calorimetry, birefringence, x-ray diffraction, and in vitro exposure to pH 7.4 phosphate buffered saline at 37°C. Fabrication was reproducible and results indicated that tensile strength, modulus, and birefringence all increased with increasing draw ratio up to a draw ratio of 6.7 and declined thereafter; elongation to failure decreased for the entire range studied. For fibers with a draw ratio of 6.7, there was a 10% relative difference in crystallinity between the 90/10 and 85/15 lactide fibers (90/10 was higher). Wet strength retention after 12 weeks in vitro exposure was approximately 10% for the 90/10 fibers and 30% for the 85/15 fibers. The intermediate wet strength retention of lactide stereocopolymer fibers when compared to reported values for PGA and PLLA fibers, suggests these materials may be useful in absorbable surgical implants for tissue repair and regeneration. © 1994 John Wiley & Sons, Inc.
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    Biomechanical aspects on rehydrated freeze-dried human allograft dura mater tissues (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 265-270 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biomechanical properties of rehydrated freeze-dried human dura mater tissues were studied. Scanning electron and polarized light analysis indicated a multilayered distribution of collagen fibers in the dura mater tissue. Uniaxial tensile testing of 95 test strips permitted determination of average values for failure stress (6.65 ± 0.14 MPa), failure strain (0.15 ± 0.003), tangent modulus (69.50 ± 1.29 MPa), elongation (0.56 ± 0.01), and tangent stiffness (12.53 ± 0.24 kN/m) of the dura mater tissue. © 1994 John Wiley & Sons, Inc.
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    Erratum (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 273-273 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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    URL: http://dx.doi.org/10.1002/jab.770050315
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    Stimulation of bone healing by transforming growth factor-beta1 released from polymeric or ceramic implants (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 141-150 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The ability of transforming growth factor-beta1 (TGF-β1) to stimulate bone healing was evaluated in a rat critical calvarial defect model. Both a low dose and a high dose of TGF-β1 were incorporated into two different types of implants: one made from a composite of poly(lactic-co-glycolic acid) (PLPG) (50:50) and demineralized bone matrix (DBM), and the other from calcium sulfate (CaSO4). Scanning electron microscopy showed that the CaSO4 implants were more porous than the PLPG/DBM samples. Both types of implants released biologically active TGF-β1 for over 300 h in vitro. The samples were implanted in a 9-mm diameter rat calvarial defect for 6 weeks along with contralateral control implants containing no TGF-β1. Microradiography and histological analysis were used to assess the bone healing in the defects. Microradiography revealed that the greatest amount of calcified bone (67.5%) was present in the CaSO4 implants containing a high dose of TGF-β1 while minimal new bone formation occurred in the PLPG/DBM implants. Histologically, the PLPG/DBM implants exhibited an inflammatory response with little mineralization or bone formation. The defects containing the PLPG/DBM implants consisted of a connective tissue stroma with large void spaces. Giant cells and numerous polymorphonuclear leukocytes were present throughout the implants. In contrast, the CaSO4 implants had only a few inflammatory cells and the presence of mineralization and true bone was a more consistent feature. These preliminary studies show that TGF-β1 is capable of inducing new bone formation. Furthermore, the materials used to deliver the growth factor can play a significant role in the bone healing process. © 1994 John Wiley & Sons, Inc.
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    Six bioabsorbable polymers: In vitro acute toxicity of accumulated degradation products (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 151-157 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bioabsorbable polymer implants may provide a viable alternative to metal implants for internal fracture fixation. One of the potential difficulties with absorbable implants is the possible toxicity of the polymeric degradation products especially if they accumulate and become concentrated. Accordingly, material evaluation must involve dose-response toxicity data as well as mechanical properties and degradation rates. In this study the toxicity and rates of degradation for six polymers were determined, along with the toxicity of their degradation product components. The polymers studied were poly(glycolic acid) (PGA), two samples of poly(L-lactic acid) (PLA) having different molecular weights, poly(ortho ester) (POE), poly(∊-caprolactone) (PCL), and poly(hydroxy butyrate valerate) (5% valerate) (PHBV). Polymeric specimens were incubated at 37°C in 0.05 M Tris buffer (pH 7.4 at 37°C) and sterile deionized water. The solutions were not changed during the incubation intervals, providing a worst-case model of the effects of accumulation of degradation products. The pH and acute toxicity of the incubation solutions and the mass loss and logarithmic viscosity number of the polymer samples were measured at 10 days, 4, 8, 12, and 16 weeks. Toxicity was measured using a bioluminescent bacteria, acute toxicity assay system. The acute toxicity of pure PGA, PLA, POE, and PCL degradation product components was also determined. Degradation products for PHBV were not tested. PGA incubation solutions were toxic at 10 days and at all following intervals. The lower molecular weight PLA incubation solutions were not toxic in buffer but were toxic by 4 weeks in water. The other materials did not produce toxic responses during the 16-week exposures. The degradation products components in order from most toxic to least toxic are: lactic acid (PLA), ∊-caproic acid (PCL), glycolic acid (PGA), cyclohexane dimethanol (POE), propionic acid (POE), 1,6 hexane diol (POE), pentaerythritol dipropionate (POE), and pentaerythritol (POE). © 1994 John Wiley & Sons, Inc.
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    Surface modification of polymeric biomaterials by albumin grafting using γ-irradiation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 163-173 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polymeric biomaterial surfaces were modified by albumin grafting to improve their blood compatibility. Albumin molecules were functionalized by introducing double bonds using glycidyl acrylate. The functionalized albumin was covalently attached to various biomaterial surfaces such as polypropylene, polycarbonate, and poly(vinyl chloride) by γ-irradiation. Surface-induced platelet adhesion and thrombus formation on the albumin-grafted surfaces was examined using computer-enhanced video microscopy and scanning electron microscopy. The amount of the grafted albumin was dependent on the γ-irradiation dose and the concentration of albumin used for adsorption. The grafted albumin molecules remained on the surface even after exposure to blood for prolonged time periods. This approach was used to graft albumin to polymeric materials of an oxygenator. The albumin grafting resulted in a substantial improvement in blood compatibility as compared to control oxygenators. The covalent grafting of functionalized albumin by γ-irradiation obviates the need for premodification of chemically inert polymer surfaces. It is useful for albumin grafting to various biomaterial surfaces. © 1994 John Wiley & Sons, Inc.
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    Characterization of a polyepoxy compound fixed porcine heart valve bioprosthesis (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 159-162 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Concerns with the currently available bioprostheses are calcification, long-term durability, and suboptimal hemodynamic performance. It is well known that these concerns are all more or less related to the cross-linking reagent, glutaraldehyde or formaldehyde, used in fixing bioprostheses. To address these concerns, we undertook the development of a porcine bioprosthesis fixed with a polyepoxy compound. In the development of this polyepoxy compound valve, it was found that the porcine leaflets fixed with polyepoxy compound were softer and more pliable than those fixed with glutaraldehyde. In this study, a special microtoming technique was developed to section the biological tissue so that the fixation uniformity in distinct layers of porcine aortic wall could be characterized. The fixation index and the denaturation temperature measurements in distinct layers of aortic walls showed that the cross-linking density was uniform throughout the entire aortic wall for the polyepoxy compound fixed porcine valve. It was also noticed that the fixation index of the polyepoxy compound fixed aortic wall (91.5 ± 0.5, n =3) was not significantly different from that of its valvular leaflet (90.6 ± 0.8, n = 3). Similarly, the denaturation temperature of the polyepoxy compound fixed aortic wall (80.4 ± 0.9°C, n = 5) was statistically comparable to that of its valvular leaflet (79.0 ± 0.5°C, n = 5). The results of this study indicated that polyepoxy compound can adequately fix the entire porcine aortic wall as well as its valvular leaflets. In a preliminary study, three polyepoxy compound fixed valves were evaluated in the mitral position in a juvenile sheep model. At 5-month retrieval, no calcification could be visually observed in any of the explanted valves. © 1994 John Wiley & Sons, Inc.
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    Biomaterials lubricated for minimum frictional resistance (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 175-181 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To improve the frictional characteristics of a biomaterial, the mechanical performance of a lubricated surface was studied. In vitro friction tests showed that the coefficient of dynamic friction of the lubricated surface was about 0.01 against rabbit bladder and the coefficient of static friction increased with the preload period. The efficacy of a lubricated cystoscope was evaluated by an in vivo test simulating cystoscope operation. The maximal and the total resistance force on the cystoscope model were found to decrease with the surface lubrication. Histological study revealed that urethral damage caused by rubbing with the cystoscope model was reduced by this lubrication technique. Presumably, prolonged retention of water on the lubricated surface region prevented tissue adhesion to the foreign material. © 1994 John Wiley & Sons, Inc.
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    Announcement (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 183-183 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050212
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994) 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050301
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    Corrosion and cell culture evaluations of nickel-chromium dental casting alloys (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 203-213 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In this study, the corrosion and surface properties of four commercially available nickel-chromium dental casting alloys, were evaluated using electrochemical corrosion testing and Auger electron microscopy. The corrosion tests were conducted under cell culture conditions of 5% CO2 humidified atmosphere at 37°C in minimum essential medium (MEM) balanced salt solution, 95% MEM-5% FBS (fetal bovine serum) cell culture media, and in 95% MEM-5% FBS media after cold solution sterilization of test samples. The results of the surface and corrosion analyses were correlated to cytotoxicity and metal ion release from the alloys using agarose overlay and direct contact cell culture tests. The surface and electrochemical corrosion analyses demonstrated that the non-beryllium containing alloys were more resistant to accelerated corrosion processes as compared to the beryllium-containing alloys. All alloys demonstrated decreased corrosion rates in cell culture solutions after cold solution sterilization treatment. The corrosion products released from the nickel-based alloys failed to alter the cellular morphology and viability of human gingival fibroblasts, however they did cause reductions in cellular proliferation. The potential for accelerated corrosion and the exposure of local and systemic tissues to elevated levels of corrosion products raises concerns over the biocompatibility of these alloys. © 1994 John Wiley & Sons, Inc.
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    Polyethylene wear debris and tissue reactions in knee as compared to hip replacement prostheses (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 185-190 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Differences in bearing surface conformity and wear mechanisms suggest that the polyethylene (PE) wear debris generated by total knee replacement (TKR) prostheses should be different than that in total hip replacement prostheses (THR). To address this issue, PE wear debris and the cellular response in periprosthetic tissues from 19 failed TKRs was compared to that from 24 failed THRs using polarized light microscopy and a semiquantitative grading system. The foreign-body inflammatory reaction in the THR cases was characterized by plump macrophages with a diffuse cytoplasmic birefringence when examined under polarized light, indicating the presence of multiple submicron particles of PE. The majority of the PE particles were 〈1 μm in size and only a small fraction of the total were 〉10 μm. The foreign-body inflammatory reaction in the TKR cases was characterized by giant cells with fewer macrophages. In the TKR specimens, the size range of PE particles was broader than in the hips. PE particles between 2 and 20 μm were frequent in TKR specimens; particles 〈1 μm in length were less common than in the THR specimens. Diffuse cytoplasmic birefringence was not a characteristic of the TKR cases. These histologic differences were so consistently distinct that the source of the specimen (i.e., from a THR or TKR) could be blindly determined by light microscopy. The size distribution of the PE wear particles in these cases indicate that THRs generate a higher number of submicron PE particles and relatively few large particles while TKRs generate a broader range of particles that includes fewer submicron particles. The observed differences in the cellular responses is likely a direct result of the differences in the spectrum of PE wear particles. These differences may in part account for differences in periprosthetic bone resorption and loosening in TKRs as compared to THRs. © 1994 John Wiley & Sons, Inc.
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    Physical properties of model viscoelastic materials (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 227-234 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Previous observations on polysaccharides used as viscoelastic agents in ophthalmic surgery suggest that the pseudoplasticity of solutions of hyaluronan (HA) and the low surface tension of hydroxypropylmethylcellulose (HPMC) solutions are physical properties that make these solutions useful clinically. Our laboratories are interested in correlating the physical properties of macromolecular solutions with the ability of these molecules to protect ocular structures during eye surgery. The purpose of this study is to compare the physical properties of model viscoelastics with the properties of HA and HPMC. The results of these studies suggest that polysaccharides that form extended structures in solution at low shear rates and that are characterized by large decreases in the axial ratio at high shear rates, exhibit pseudoplastic behavior. In this study pseudoplasticity is exhibited by polysaccharides with molecular weights in excess of 450 000, and is insensitive to the backbone chemistry for linear macromolecules. In addition, low surface tension is associated with charged macromolecules that have a high positive second virial coefficient. © 1994 John Wiley & Sons, Inc.
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    Inhibition of in vitro calcium phosphate precipitation in presence of polyurethane via surface modification and drug delivery (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 245-254 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biomaterial associated calcification is the principal cause of the clinical failure of bioprosthetic implants. The present investigation describes the mineralization of polymeric substrate in an extracirculatory environment and the possible methods of prevention. Calcification was examined on various polyurethane films (and bioprosthetic tissue) incubated in metastable solutions of calcium phosphate and the role of polymer casting and precipitation was evaluated. The formulation and the in vitro efficacy of prolonged controlled-release chitosan matrices, containing the novel anticalcification agents, such as Fe+++ or protamine sulfate (PS), were also attempted. The in vitro release profiles of PS from chitosan beads was performed in a rotating shaker (100 rpm) in 0.1 M phosphate buffer (pH 7.4) and was monitored spectrophotometrically. The amount and percentage of drug release were much higher initially, which was controlled with the incorporation of egg phosphatidyl choline (EPC). The PS loaded chitosan beads (coincubated in calcium phosphate solution with the calcifiable polyurethane films) significantly inhibited biomaterial calcification (about 40-50% inhibition). Surface modification of polyurethanes with Fe+++ or PS also inhibited the calcification profile of the material. These findings suggest the possibility of a combination therapy for prevention of biomaterial associated calcification via surface modifications in conjunction with long-term controlled release of the anticalcifying drugs. © 1994 John Wiley & Sons, Inc.
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    New advances in electronic devices for hole detection (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 257-264 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Holes in surgical gloves are considered to be an important source of transmission of pathogens between surgeon and patient. Two new glove hole detectors have been devised to alert the surgeon to the presence of holes. These devices have been evaluated using six powder-free and seven powdered varieties of surgical gloves that were either dry or exposed to hydration. Eight of the 13 surgical gloves hydrated rapidly with water, altering their resistance to the conduction of electricity. Because the Barrier Integrity MonitorTM only has a hydration monitor, 68 false positives occurred during the evaluation, indicating to the surgeon that he/she should change gloves unnecessarily because the glove had no hole. In contrast, the Surgic Alert MonitorTM (SAMTM) had a hydration alarm as well as a glove hole detection alarm. During the 104 tests, the SAMTM device showed no false positives. In the testing of five of the rapidly hydrating types of surgical gloves, the SAMTM device could not reliably detect holes. On the basis of this study, the SAMTM device, in conjunction with gloves that resist hydration, appeared to be a reliable hole detection monitor. © 1994 John Wiley & Sons, Inc.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994) 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050401
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    Torsional properties of healed canine diaphyseal defects grafted with a fibrillar collagen and hydroxyapatite/tricalcium phosphate composite (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 277-283 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The need for alternatives to autogenous bone grafts is widely recognized. This study compared the torsional strength of canine femora 1 year after grafting with one of three forms of a collagen/hydroxyapatite/tricalcium phosphate bone grafting material (COLLAGRAFT15), autogenous bone, or no graft. The groups were compared to each other and to the unoperated contralateral femora. Results of torsional testing were evaluated for torsional strength, torsional displacement, total energy to fracture and White fracture mode. Data analysis showed lower torsional strength of the operated vs. unoperated femora with the exception of morsellized COLLAGRAFT15 material, which had higher strength. However, the only difference in the operated groups was that the morsellized COLLAGRAFT15 had greater strength than several groups including the autogenous bone group. There was no difference found in angular displacement between any of the groups. However, there was a difference in the energy to fracture in both strip forms of the COLLAGRAFT15. The final conclusion is that in this model, grafting with COLLAGRAFT15 provided torsional properties at one year postoperatively at least equivalent to autogenous bone. © 1994 John Wiley & Sons, Inc.
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    Use of a compact sandwich specimen to evaluate fracture toughness and interfacial bonding of bone (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 315-323 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The objective of the present study was to develop a reliable and statistically valid test to measure the fracture toughness of small specimens of bone, and by extension, prosthetic materials, using a compact sandwich specimen. Samples of bone were sandwiched between holders of a different material and using this specimen configuration a new technique was developed to test the fracture toughness of the bone interlayer. The effects of different speciments sizes and holder materials were investigated empirically. Using finite element analysis a correction factor was determined to account for the finite thickness of the interlayer and the analytical solutions governing the test specimen were accordingly modified. Bulk compact tension specimens of bone were tested for comparison. Both wet and dry bone were evaluated and the fracture surface morphology characterized using scanning electron microscopy. The results indicate no statistically significant differences between the fracture toughness values obtained from the compact tension and sandwich specimens. The application of this technique to the testing of interfacial bonding between bone and biomaterials is discussed. © 1994 John Wiley & Sons, Inc.
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    Mechanical properties of vacuum-mixed acrylic bone cement (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 307-314 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The thrust of the present work was the experimental determination of the uniaxial static compressive and fully reversed tension-compression fatigue properties of CMWTM 3 acrylic bone cement whose consituents were mixed in a properietary chamber while simultaneously subjected to a vacuum. Selected indices of performance in this material are: mean static compressive strength, 81.4 MPa; mean compressive modulus of elasticity, 1.95 GPa; endurance limit, 8.1 MPa; and characteristic fatigue life (using a three-parameter Weibull fit to the fatigue test data obtained at a stress of ±10 MPa), 238 712 cycles. The difficulties in comparing results obtained using different cement formulations, preparation conditions, and test conditions are detailed. With this in mind, it is suggested that the present results are within the range of values reported by previous workers for other formulations mixed using a variety of methods. The clinical significance of the present results is discussed. © 1994 John Wiley & Sons, Inc.
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    Ciprofloxacin attachment to porous-coated titanium surfaces (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 325-331 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A simple and effective method for attaching ciprofloxacin HCl salt to the surface of porouscoated titanium based orthopedic materials was developed. The method utilizes the electrophoretic migration of both fine ciprofloxacin HCl particles and ciprofloxacin ions to deposit the antibiotic salt on a positively biased surface. The quantity of antibiotic deposited can be easily and effectively controlled by varying the time of deposition and applied voltage. In vitro tests have indicated that the antimicrobial activity of the treated surfaces is retained for a period of 5 days. The method allows a significant amount of antibiotic to be deposited and could theoretically be used to deliver antibiotics to the tissues surrounding prosthetic devices in order to prevent postoperative infections. © 1994 John Wiley & Sons, Inc.
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    Effects of fixation technique on displacement incompatibilities at the bone-implant interface in cementless total knee replacement in a canine model (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 349-352 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bone-implant displacements can be caused by rigid body motion and by differences in material properties of the implant and bone. In the present study of the tibial component in total knee replacement, we tested a series of tibial component fixation designs to determine how certain design features influenced the magnitude of the tangential displacement between the component and supporting bone in a canine model. The transverse expansion of the proximal tibia under static axial loading was measured in the intact tibia and then in the same bone following implantation of tibial components with different interface characteristics: cementless flat smooth, cementless flat porous-coated, cementless flat porous-coated with screws, cementless pegged porous-coated, cementless pegged porous-coated with screws, cemented pegged, and cemented pegged with screws. In all cases, the magnitude of the transverse expansion increased with higher applied loads. When the statistical analysis was restricted to the cementless interfaces, the presence/absence of the porous coating, the presence/absence of pegs, and the use of screws had no significant influence on tibial expansion. However, in an analysis including the cemented and cementless pegged components, tibial expansion was reduced with the use of screws. The magnitude of the interface motion due to these displacement incompatibilities was approximately fivefold lower than the amount of interface motion related to rigid body motion found in a separate study with the canine model. The measured expansion was similar in the intact tibiae and the implanted tibiae, suggesting that the transverse constraint in the canine proximal tibia must be provided by the surrounding cortical ring rather than the subchondral bone. © 1994 John Wiley & Sons, Inc.
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    Improved sensitivity and decreased sample size in a cytotoxicity test for biomaterials: A modified colony microassay using a microplate and crystal violet staining (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 361-367 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Modified Eagle's minimum essential medium supplemented with 5% fetal calf serum was highly sensitive to cytotoxicity and formed large control colonies in the V79 colony assay. A highly sensitive cytotoxicity test was developed using 96-well microtiter plates. Test chemicals or extracts of polyurethane materials containing the same chemicals were added 24 h after inoculation of cell suspensions. The cells were fixed and stained with crystal violet after additional culture for 6 days (V79 cells) or 10 days (Balb/3T3 cells). In terms of sensitivity and rapid quantitative measurement, this modified colony microassay, using a low cell density in 96-well microplates, was superior to various cytotxicity tests such as colony, growth inhibition, cytolethality, and agar diffusion assays. © 1994 John Wiley & Sons, Inc.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994) 
    Details
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860030101
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    Controlling the interface between II-VI and III-V semiconductors (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 3-9 
    Details
    ISSN: 1057-9257
    Keywords: Heteroepitaxy ; Raman spectroscopy ; In situ characterisation ; II-VI/III-V ; CdTe ; CdS ; III2VI3 ; Interface ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: This paper describes ways in which the interface between II-VI and III-V semiconductors can be controlled so as to suppress or alter commonly observed interfacial reactions. This will be done using CdTe/InSb and CdS/InP heterostructures as examples. In the case of CdTe/InSb a modification of the interfacial properties is achieved by a variation in the II/VI ratio offered to the surface during growth, while the influence of Sb interlayers is studied for CdS on InP. Information on the interface properties is obtained from Raman spectroscopy. While structural and electronic properties of the II-VI layer can be deduced from the scattering intensities of its characteristic vibrational modes, the formation of interfacial compounds is observed by the appearance of scattering intensity in a different spectral range, which is consistent with the formation of III2VI3 compounds. The potential of Raman spectroscopy for on-line in situ monitoring of growth processes will be displayed.
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    Stimulated emission in ZnSxSe1 - x/ZnSe heterostructures grown by MOVPE (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 73-80 
    Details
    ISSN: 1057-9257
    Keywords: MOVPE ; ZnSxSe1 - x ; MQW ; Optical properties ; Lasing Exciton ; Electron-hole plasma ; Dynamics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Non-linear and stimulated emission of ZnSxSe1 - x/ZnSe multilayer structures grown by MOVPE on GaAs is investigated by means of high-density excitation spectroscopy using a high-resolution pulsed excimer-dye laser system as well as a picosecond titanium-sapphire laser for time-resolved measurements. Heterostructures with ZnSe layers or single and multiple quantum wells were grown in which the ZnSe layer widths were varied between 1 nm (strong quantum confinement) and 500 nm (quasi-bulk situation). The sulphur concentration in the ZnSxSe1 - x buffer, barrier and cap layers was chosen between x = 0.045 and x = 0.74 in order to find the most promising compromise with regard to maximum band offset to ZnSe for most efficient carrier confinement and suitable waveguiding properties depending on variation in the refractive index, and to highest structural quality of the actively emitting ZnSe layers. Stimulated emission is found to occur in all samples, being brightest in the sample with the lowest sulphur concentration in the cap and barrier layers. Its dynamical properties point to a probable interpretation in terms of electron-hole plasma creation, which, however, may not be the basic process in narrow-quantum wells or strongly structurally disturbed samples.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030111
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    Laser processes in wide gap II-VI semiconductors (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 103-109 
    Details
    ISSN: 1057-9257
    Keywords: Laser emission ; II-VI semiconductors ; Many particle effects ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: After a brief historical remark about the evolution of scientific interest in wide gap II-VI compounds, we review the various laser processes which have been identified in bulk materials and thin layers during the last 25 years. We then proceed to quantum wells and superlattices and stress the differences from III-V compounds. We finish by considering the exploitation of specific properties of widegap II-VI compounds for light-emitting and laser diodes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860030115
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  • 83
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    Dynamical aspects of free exciton-magnetic polaron formation in CdTe-Cd1 - xMnxTe quantum wells (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 117-125 
    Details
    ISSN: 1057-9257
    Keywords: Exciton-magnetic polaron ; Quantum well ; Dilute magnetic semiconductors ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Calculations of the energies of magnetic polarons formed by free excitons localised in non-magnetic CdTe wells next to magnetic Cd1 - xMnxTe barriers are presented. A comparison with recent time-resolved spectroscopy results allows insight to the physical aspects governing the dynamics of the formation of the polarons. It is shown that the experimentally measured energy shift is not the polaron energy itself but the difference between this and the change in the exciton binding energy. The latter is calculated within the envelope function approximation and by employing a variational technique. The polaron energy calculation uses a modified version of an approach described by Wolff.The results show that static polaron calculations are not generally reliable and that the exciton-magnetic polaron has to be viewed as a dynamically evolving complex. It is initially energetically favourable for the exciton-magnetic polaron complex to increase its spatial localisation, since the gains in polarisation energy exceed the loss in exciton binding energy. However, thermodynamic considerations suggest that in general saturation of the magnetic ions will not occur.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030117
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  • 84
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    Spin-polarised tunnelling current in metal-insulator-gapless semiconductor structures in a magnetic field (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 127-130 
    Details
    ISSN: 1057-9257
    Keywords: Tunneling ; Gapless semiconductor ; Magnetic field ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Experimental investigations of tunnelling conductivity oscillations of metal-insulator-gapless semiconductor structures are performed. For the orientation of the magnetic field H | n (n is normal to the structure plane) a splitting of the oscillation maxima of the tunnelling conductivity due to the spin splitting of the Landau levels is observed. It is revealed that when the magnetic field turns away from this direction the amplitudes of the low-bias maxima decrease monotonously, and at H ⊥ n oscillations corresponding to tunnelling into one spin state only are observed. A theoretical analysis shows that this is caused by an unusual behaviour of the electron wavefunctions near the surface of gapless semiconductors in an applied magnetic field.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030118
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  • 85
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    Homogeneious linewidth and relaxation of excited hole states in II-VI quantum dots (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 141-150 
    Details
    ISSN: 1057-9257
    Keywords: Semiconductor-doped glasses ; Non-linear optical materials ; Differential absorption spectroscopy ; Scattering processes ; II-VI compounds ; Quantum dots ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: By use of differential absorption spectroscopy at different temperatures we investigate the homogeneous line broadening of small CdSxSe1 - x quantum dots embedded in glass. Our experiments show the strong correlation between the precipitation stages and characteristics optical parameters such as the saturation intensity and the longitudinal and transverse relaxation times. In samples grown in the diffusion-controlled regime to avoid coalescence, we find after strong laser excitation for the first time spectrally narrow holes in the non-linear differential absorption spectra. These sharp non-linear resonances with a halfwidth Γ of only 10 meV at T = 20 K allow us to investigate the energetic distance of the lowest hole levels and the temperature dependence of the line broadening. The different contributions of LO phonon coupling and temperature-independent scattering to the homogeneous linewidth will be analysed. The relaxation from the excited hole states has been investigated by exciting in the higher-energy hole states and measuring the resulting change in the ground state absorption.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030121
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  • 86
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    High-resolution scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) of ZnSxSe1 - x/ZnSe Quantum Wells (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 183-190 
    Details
    ISSN: 1057-9257
    Keywords: Scanning transmission electron microscopy (STEM) ; High-resolution ; Z-contrast ; ADF ; HAADF ; Electron energy loss spectroscopy (EELS) ; ZnSxSe1 - x/ZnSe quantum wells ; MOVPE ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Epitaxial growth techniques for ZnSxSe1 - x/ZnSe heterostructures have already achieved a high degree of development. Further improvements strongly require characterisation techniques with high compositional sensitivity and high spatial resolution. Therefore in this work high-resolution Z-contrast, which provides compositional information down to the atomic scale, has been used for the first time to characterise ZnSxSe1 - x/ZnSe quantum well structures. The influence of structural defects on Z-contrast is demonstrated by comparison of scanning transmission electron microscopy (STEM) bright field images and STEM Z-contrast micrographs of planar defects and dislocations. The compositional abruptness of ZnSxSe1 - x/ZnSe interfaces in MOVPE-grown quantum well (QW) structures is judged from high-resolution Z-contrast micrographs. Electron energy loss spectroscopy (EELS) measurements were performed for the first time in ZnSxSe1 - x/ZnSe QW structures in order to obtain quantitative compositional information with nanometre spatial resolution. From EELS line scans, which monitor the selenium concentration across ZnSe QWs, the obtainable spatial resolution is estimated to be about 1-2 nm. The problems that have prevented quantitative analysis of the selenium concentration up to now are discussed.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030126
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  • 87
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    Plasma-enhanced MOVPE and nitrogen doping of ZnSe (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 203-208 
    Details
    ISSN: 1057-9257
    Keywords: ZnSe ; Diallylselende ; Plasma ; MOVPE ; Nitrogen doping ; Raman spectroscopy ; Photoluminescence ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: In order to obtain high quality Znse epilayers on GaAs which can be intentionally P- and n-type doped growth at a reduced temperature is highly desirable. Therefore in this work the suitability of diallylselenide and the influrnce of plasma precracking have ben investigated. Photoluminesscence, Raman spectroscopy, scanning electron microscopy, X-ray, SIMS and Hall measurements were used to anaylse the samples. The selenium precursor was fully decomposed at temperatures above 360°C if it was precracked by a plasma. Bound excitions could be resolved with negligible donor-acceptor pair (DAP) and copper green emission in the PL spectra form films which were grown with a plasma at temperatures beyond 530°C. Clearly the hpe for reduction in the deposition temperature was not achieved. Raman spectra also revealed strong crystalline quality variations. For the doping experiments nitrogen was used as the carrier gasa instead of hydrogen. Plasma cracking of the selenium precursor was still necessary. Thye substitution of the H2 carrier gas by nitrogen reduced the growth rate by a factor of 2.6 but enhanced the crystalline properties of the samples as shown by the Raman measurements. Strong DAP emission at 2.7eV in the (PL) spectra was observed. SIMS measurements showed a nitrogend concertration of about 3 × 1017 cm-3. An additional nirtogen plasama (0-7W) had a begligible effect on the nitrogen concentration in the sample. The samples were semi-insulating, whichmight be a conswquence of the crystalline quality of ZnSe grown with DASe as selenium precursor.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030129
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  • 88
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    GaAs substrates for the MOVPE growth of (Hg,Cd)Te layers (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 239-245 
    Details
    ISSN: 1057-9257
    Keywords: Substrates ; MOVPE ; MCT ; Surface morphology ; Structural properties ; Photoconductors ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: After a review of the structural properties of (Hg,Cd)Te layers grown by MOVPE on GaAs substrates, topical questions such as out-diffusion of Ga and As from the substrate into the layers, monolithic integration of signal procesing into the substrate and the presence of pyramidal defects in (100) layers will be discussed. In order to solve the last problem, a systematic study of the influence of the (h11) GaAs substrate orientation and polarity on the structrual properties and surface morphology of CdTe layers grown by MOVPE has ben carried out. Twin-free layers are obtained on (211)A, (311)B and (511)B GaAs surface orientations as ezplained by a model taking into accountthe type of dangling bonds at the interface. The performance of photoconductors fabricated on(Hg,Cd)Te layers of various orientations confirms these results. Particularly good results have been obtained for the (311)B orientation.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030134
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  • 89
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    Photoluminescence spectroscopy as a tool to assess extrinsic impurities and quality of ZnSe and ZnSxSeI - x grown by MOVPE (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 261-267 
    Details
    ISSN: 1057-9257
    Keywords: ZnSe ; ZnSxSe1 - x ; MOVPE ; Photoluminescence ; Mapping ; Purified ; DESe source ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: In this paper we report new results concerning the cause of impurities responsible for the Ix, and I2-peaks in photoluminescence (PL) spectra of ZnSe grown by MOVPE. An improvement in ZnSe epilayer quality is obtained by using a metal organic selenium precursor with reduced chlorine concentration. The PL spectrum of such a layer shows typical excitonic transitions, but compared with samples grown with a more contaminated source, the intensity of the Ix, and the I2 peaks decreases relative to the free exciton transition. A Gaussian fitting of the donor-bound exciton peaks taking the background of other structures into account shows that the ratio between the Ix and I2 peaks does not differ significantly between two samples. Both the decrease in donor-bound exciton transitions and the unchangeability of the ratio Ix/I2lead to the conclusion that only chlorine impurities are responsible for Ixand Ix. In order to verify the homogeneity of impurity uptake across a 2 inch wafer, we performed PL mapping of ZnSxSe1 - x layers. Mapping of a 2 inch ZnSe wafer shows that the FWHM of Ix across a wafer does not vary significantly (1.55 ± 0.21 meV). On mapping a 2 inch ZnS0.3Se0.7 wafer fabricated with H2S as the sulphur source at TD = 480°C, we found a rotational symmetric dstribution of sulphur in the layer. The sulphur content x at the centre is nearly constant. The difference in x between the centre and the boundary of a bad surface region at the edge of the wafer is less than Δx = 0.045. The FWHM of the band edge luminescence follows the same tendency across the wafer. The dependence of homogeneity on the reactor design as well as the uptake of unintentional impurities from the precursor is discussed in detail.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030137
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  • 90
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    Phosphorescent spectral and decay studies of CaI - xSrxS:Ce solid solutions (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 283-288 
    Details
    ISSN: 1057-9257
    Keywords: Phosphors ; Alkaline ; Earth sulphides ; Photoluminescence ; CaS ; SrS ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Ca1 - xSrxS Solid Solutions at 10 m/o intervals have been prepared by coprecipitation of sulphates from aqueous solution followed by reduction at 1000°C with hydrogen. Phosphorescence emission spectra have been determined for these solid solutions doped with 0.1 m/o cerium and show a blue shift with increasing strontium content from 2.46 to 2.59 eV. Hyperbolic phosphorescent decay curves were observed at both room and liquid nitrogen temperatures across the composition range and have been broken down into three exponential components by graphical and computer-programme-based methods. At room temperature trap depth values of 0.366, 0.316 and 0.282 eV with measured lifetimes of 1.9, 0.26 and 0.07 ms respectively were determined with little dependence on composition. At liquid nitrogen temperature shallower traps were observed at 0.103, 0.086 and 0.076 eV with respective decay times of 5, 0.4 and 0.09 ms having little sensitivity to changes in the host compostion. These traps are related to intrinsic defects, some of which may be surface in character. The blue shift in emission peak energy with the decrease in band gap from CaS to SrS is discussed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030140
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  • 91
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    A new, thermally efficient route to crystalline BaTiO3 from monodispersed rutile powder (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 9-17 
    Details
    ISSN: 1057-9257
    Keywords: Barium ; Rutile ; Ammonia ; Barium titanate ; X-ray powder diffraction ; Scanning electron microscopy ; Thermogravimetric analysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Treatment of monodispersed rutile (TiO2) powder with an ammonlacial solution of elemental barium gives a uniformly coated precursor to BaTiO3. Thermolysis at about 900 °C for 6 h gives crystalline (by XRS) material with an average particle size of less than 0.1 μm (as determined by SEM).
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860040103
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    Liquid crystal flat panel displays. W. C. O'Mara. Van Nostrand Reinhold (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 51-52 
    Details
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040108
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    Guest editorial (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 53-53 
    Details
    ISSN: 1057-9257
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860040202
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  • 94
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    Silylation and dry procession (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 129-138 
    Details
    ISSN: 1057-9257
    Keywords: Silylation ; Dry development ; Photoresist ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The issues of dry development and self-developing resists are addressed in this paper by way of an introduction to the main topic of surface imaging, in which diffusion-enhanced vapour plhase silylation chemistries and their mechanisms are developed with specific reference to resists that function through the DESIRE process. More recent liquid phase silylation processes are also considered.
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    URL: http://dx.doi.org/10.1002/amo.860040207
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    Wet development of polymer resists: A guide to solvent selection (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 4 (1994), S. 155-163 
    Details
    ISSN: 1057-9257
    Keywords: Wet development ; θ-Solvents ; Cosolvents ; Rate of dissolution ; Polymer resists ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The criteria for selecting effective solvent systems for wet development of polymer resist materials are explored. Methods of estimating the polymer-solvent interactions are described, including the use of solubility parameters and the Flory-huggins interaction parameter. Methods of achieving θ-conditions, which represent minimal solvent-precipitant mixtures, or the more novel approach of establishing cosolvent systems are described. The rate dissolution has also bee identified as a controlling parameter. Some optical and gravimetric methods for measuring dissolution rates for polymer films are outlined. Examples of the influence of these factors on the sensitivity and contrast of resists such as poly(methylmethacrylate) and poly(p-methyl styrene-stat-chloromethyl styrene) are described.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860040209
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  • 96
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    Phase transition from the cubic to the hexagonal modification in thin CdS films on InP(110) (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 11-14 
    Details
    ISSN: 1057-9257
    Keywords: Heteroepitaxy ; CdS ; Crystal structure ; Photoluminescence ; Reflection ; Thin films ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: CdS films were prepared by molecular beam epitaxial growth on clean cleaved InP(110) substrates. Films with thicknesses in the 200 nm range were studied by optical techniques: spectroscopic ellipsometry, reflection and photoluminescence. The film thickness and the dielectric function of the films are evaluated from the ellipsometry data. The feature in the imaginary part of the film dielectric function which is induced by the E1 interband transition in CdS is found to be extremely sensitive to the crystal modification. A splitting of this feature occurring at approximately 200 nm indicates a phase transition in the thin films from the cubic to the hexagonal modification. This is confirmed by reflection measurements which show two series of reflection loops for both modifications for film thickness exceeding 200 nm. The energy positions of the free excitons of the hexagonal and cubic modifications are derived. In addition, the band gap for the cubic modification is determined for the first time. The photoluminescence spectra also reveal cubic and hexagonal contribution of donor-acceptor pair recombinations. From the excitonic transitions attempts are made to identify the main impurities in the layers.
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    URL: http://dx.doi.org/10.1002/amo.860030104
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    Gain and dynamics of excitons in MOVPE-grown ZnSe/ZnSxSe1 - x heterostructures (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 51-55 
    Details
    ISSN: 1057-9257
    Keywords: MOVPE ; Quantum wells ; ZnSe/ZnSxSe1 - x heterostructures ; Gain ; Excitons ; Luminescence dynamics ; Transfer processes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Optically pumped stimulated emission in ZnSe/ZnSxSe1 - x heterostructures grown by MOVPE has been observed up to 170 K. Gain measurements have been performed using the variable stripe length method. The underlying gain mechanism at 25 K is atributed to an excitonexciton scattering process. Photoluminescence excitation spectra and the temporal evolution of the luminescence indicate a transfer process from the ZnSxSe1 - x barrier into the ZnSe active layer.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030108
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    Experimental and theoretical aspects of electrical characteristics of Au/ZnSe/GaAs heterostructures (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 81-88 
    Details
    ISSN: 1057-9257
    Keywords: Semiconductor heterojunctions ; Admittance ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: We present results of a theoretical and experimental study of Au—ZnSe—GaAs heterostructures. In the theoretical part we report the band diagrams, charge densities and static I-V curves obtained from a detailed numerical analysis. In the experimental part we give the results for the static I-V curves and frequency-dependent admittance and impedance at different bias voltages for an Au—ZnSe—GaAs heterostructure with a ZnSe layer of 2.75 μm thickness. An explicit analysis of the data shows that the system can be represented by an equivalent circuit of two RC elements in series corresponding to the ZnSe—GaAs and Au—Se heterojunctions.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/amo.860030112
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    The role of ZnS in ZnS/SrS:Ce,Cl multilayered TFEL devices (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 111-116 
    Details
    ISSN: 1057-9257
    Keywords: II-VI compounds ; Electroluminescence ; ZnS ; SrS ; CeCl3 ; Multilayer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Different ZnS/SrS:Ce,Cl multilayered electroluminescent devices have been prepared by a multisource deposition method. The highest luminance achieved in this investigation is 1540 cd m-2 at 1 kHz using a stack of nine alternating layers of ZnS and SrS:Ce,Cl; the highest luminance in the blue exceeds 14 cd m-2 at 60 Hz, 50 μs pulse excitation. The influence of the ZnS thickness on device performance and stability has been investigated. The electrical and optical behaviour of standard and multilayered devices in time-resolved measurements is compared.
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    URL: http://dx.doi.org/10.1002/amo.860030116
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  • 100
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    Tackling problems in the growth of ZnS/Se through precursor design (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 163-169 
    Details
    ISSN: 1057-9257
    Keywords: Zinc sulphide ; Zinc selenide ; t-butanethiol ; Precursors ; Purification ; Multilayers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: A variety of problems in the growth of wide band gap II/VI materials by MOVPE has been addressed by the use of alternative precursors. The quality of grown layers of ZnSe has been greatly improved by adduct purification of Me2Zn. Using 4,4′-bipyridyl, the recovery of Me2Zn is variable because of the insolubility of 4,4′-bipyridyl in diethylether. Higher yields can be obtained using the ether-soluble base 1,3-bis(4-pyridyl)propane.tBuSH has been introduced for the growth of ZnS. Being a liquid, this compound is easy to handle and it allows growth of high-quality ZnS at temperatures down to 325°C with very little gas phase pre-reaction with Me2Zn. Growth of ZnSxSe1 - x at atmospheric pressure using H2S and Et2Se as the group 16 precursors allows excellent stoichiometric control, since the ratio of S : Se in the grown solid is similar to that of H2S : Et2Se in the gas phase for all compositions. Finally, multilayer structures have been grown at low pressure with excellent interface abruptness and goodquality material. However, the ternary layers are all much higher in sulphur than expected from the gas phase composition and the composition of the ternary appears to be influenced by the nature of the surface on which it is growing.
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    URL: http://dx.doi.org/10.1002/amo.860030123
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