ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Counterdiffusion of liquid hydrocarbons in type Y zeolite: Effect of molecular size, molecular type, and direction of diffusion (1972)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 18 (1972), S. 816-824 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents experimental results on the counterdiffusion of liquid hydrocarbons in the Y zeolite as determined by an unsteady state technique using the zeolite powder. The critical diameter of aromatic molecules counterdiffusing with respect to cyclohexane into NaY zeolite has a marked effect upon the counterdiffusion rate. For a given molecular type, the single parameter of critical molecular diameter correlates the size effect well. Molecular type, for example, toluene vs. phenol, also has a pronounced effect on the counterdiffusion rate. Those molecules showing stronger interactions with the zeolite have lower counterdiffusion rates. In both NaY and SK-500, the diffusion coefficients for adsorptive counterdiffusion are an order of magnitude greater than the diffusion coefficients for desorptive counter-diffusion indicating that factors other than simple intracrystalline diffusion as such are also important in zeolite counterdiffusion. Simple diffusion models do not account for the differences observed indicating that a more sophisticated approach is necessary.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690180426
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Extracellular microbial polysaccharides. I. Substrate, biomass, and product kinetic equations for batch xanthan gum fermentation (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 22 (1980), S. 859-873 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various biomass (X), product (P), and substrate (S) rate equations are considered in order to synthesize a general xanthan fermentation model from literature data. Analytical forms that provide reasonable descriptions for the X, P, and S behaviors reported by Moraine and Rogovin are shown to be the logistic equation, the Luedeking-Piret equation a modified Luedeking-Piret equation, respectively. The autonomous logistic equation allows the serial evaluation of parameters for all thee equations, rather than a simultaneous determination required by nonautonomous models.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260220410
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Microcontact printing and electroplating on curved substrates: Production of free-standing three-dimensional metallic microstructuresThis research was supported in part by the National Science Foundation (PHY-9312572). ONR and DARPA. and by the William F. Milton Fund of the Harvard Medical School. It also used MRSEC Shared Facilities supported by the NSF under award number DMR-94(X)396. JAR gratefully acknowledges funding from the Harvard University Society of Fellows, and RJJ gratefully acknowledges a scholarship from NSFRC of Canada. (1997)
    Weinheim : Wiley-Blackwell
    Advanced Materials 9 (1997), S. 475-477 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19970090603
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Demonstration of a nanolithographic technique using a self-assembled monolayer resist for neutral atomic cesiumThis work was supported in part by NSF grant PHY 9312572 and made use of the Harvard MRSEC shared facilities. The authors acknowledge Hans Robinson, Dr. Hans Biebuyck, Dr. James L. Wilbur, and Dr. Jabez McClelland, for assistance with the initial stages of this work. The authors also thank Dr. Yuanchang Lu for assistance in generating SEM images, Joseph Thywissen for a careful reading of the manuscript, and Kent Johnson, Dr. Andreas Bard, and Dr. John Gillaspy for many helpful discussions. (1997)
    Weinheim : Wiley-Blackwell
    Advanced Materials 9 (1997), S. 52-55 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19970090111
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Transport characterization of hydrogel matrices for cell encapsulation (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 50 (1996), S. 365-373 
    Details
    ISSN: 0006-3592
    Keywords: hydrogel ; diffusion ; alginate ; agarose ; cell encapsulation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Current membrane-based bioartificial organs consist of three basic components: (1) a synthetic membrane, (2) cells that secrete the product of interest, and (3) an encapsulated matrix material. Alginate and agarose have been widely used to encapsulate cells for artificial organ applications. It is important to understand the degree of transport resistance imparted by these matrices in cell encapsulation to determine if adequate nutrient and product fluxes can be obtained. For artificial organs in xenogeneic applications, it may also be important to determine the extent of immunoprotection offered by the matrix material. In this study, diffusion coefficients were measured for relevant solutes [ranging in size from oxygen to immunoglobulin G (IgG)] into and out of agarose and alginate gels. Alginate gels were produced by an extrusion/ionic crosslinking process using calcium while agarose gels were thermally gelled. The effect of varying crosslinking condition, polymer concentration, and direction of diffusion on transport was investigated. In general, 2-4% agarose gels offered little transport resistance for solutes up to 150 kD, while 1.5-3% alginate gels offered significant transport resistance for solutes in the molecular weight range 44-155 kD - lowering their diffusion rates from 10- to 100-fold as compared to their diffusion in water. Doubling the alginate concentration had a more significant effect on hindering diffusion of larger molecular weight species than did doubling the agarose concentration. Average pore diameters of approximately 170 and 147 Å for 1.5 and 3% alginate gels, respectively, and 480 and 360 Å for 2 and 4% agarose gels, respectively, were estimated using a semiempirical correlation based on diffusional transport of different-size solutes. The method developed for measuring diffusion in these gels is highly reproducible and useful for gels crosslinked in the cylindrical geometry, relevant for studying transport through matrices used in cell immobilization in the hollow fiber configuration. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Cartilage production by rabbit articular chondrocytes on polyglycolic acid scaffolds in a closed bioreactor system (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 299-305 
    Details
    ISSN: 0006-3592
    Keywords: cartilage ; polyglycolic acid ; chondrocytes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rabbit articular chondrocytes were seeded onto three-dimensional polyglycolic acid (PGA) scaffolds and placed into a closed bioreactor system. After 4 weeks of growth, meshes were examined for cartilage formation. Gross examination revealed solid, glistening material that had the appearance of cartilaginous tissue. Histologic examination revealed cell growth and deposition of extracellular matrix throughout the mesh with a less dense central core. Alcian blue and Safranin 0 staining showed deposition of glycosaminoglycans (GAGs). Immunostaining showed positive reactivity for type II collagen and chondroitin sulfate and no reactivity for type I collagen. Biochemical analysis showed collagen and GAG values to be 15% and 25% dry weight, respectively. Our results indicate that this type of system compares well with those previously described and should be useful for producing cartilage for evaluation in a clinical setting. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260460402
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Stability of hydrogels used in cell encapsulation: An in vitro comparison of alginate and agarose (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 50 (1996), S. 374-381 
    Details
    ISSN: 0006-3592
    Keywords: hydrogel ; stability ; gel strength ; diffusion ; alginate ; agarose ; encapsulation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The present studies were undertaken to evaluate the in vitro gel stability of the hydrogels alginate and agarose. Gel strength (of alginate and agarose) and protein diffusion (of alginate only) were shown to correlate with gel stability and to be useful techniques to monitor gel stability over time. The gel strengths of alginate and agarose were followed for a 90-day period using gel strength as a measure of gel stability. The gel strength of agarose diminished in the presence of cells because the cells likely interfered with the hydrogen bond formation required for agarose gelation. In the presence of cells, the gel strength of agarose decreased by an average of 25% from time 0 to 60 days, thereafter maintaining that value to 90 days. The gel strength of calcium- or barium-crosslinked alginate decreased over 90 days, with an equilibrium gel strength being achieved after 30 days. The presence of cells did not further decrease alginate gel strength. The gel strengths of calcium- and barium-crosslinked alginates were similar at 60 days - 350 ± 20 g and 300 ± 60 g, respectively - indicating equivalence in their stability. The stability of calcium-crosslinked sodium alginate gels over a 60-day time period was monitored by diffusion of proteins ranging in molecular weight from 14.5 to 155 kD. From these diffusion measurements, the average pore size of the calcium-crosslinked alginate gels was estimated, using a semi-empirical model, to increase from ∼176 to 289 Å over a period of 60 days. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    Thrombin, epidermal growth factor, and phorbol myristate acetate stimulate tubulin polymerization in quiescent cells: A potential link to mitogenesis (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 23 (1992), S. 265-278 
    Details
    ISSN: 0886-1544
    Keywords: growth factors ; phorbol 12-myristate 13-acetate ; microtubule-tubulin equilibrium ; initiation of DNA synthesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previous studies suggest that alterations in the microtubule (MT)-tubulin equilibrium during G0/G1 affect mitogenesis. To determine the effect of growth factors on the MT-tubulin equilibrium, we developed a radioactive monoclonal antibody binding assay (Ball et al.: J. Cell. Biol. 103:1033-1041, 1986). With this assay, 3H-Ab 1 - 1.1 binding to cytoskeletons in confluent populations of cultured cells is proportional to the number of tubulin subunits polymerized into MTs. We now show that purified α-thrombin increases 3H-Ab 1 - 1.1 binding to cytoskeletons of serum-arrested mouse embryo (ME) fibroblasts from 1.5- to 3-fold. This stimulation is dose-dependent and correlates with concentrations of thrombin required for initiation of DNA synthesis. Other mitogenic factors, epidermal growth factor (EGF) and phorbol 12-myristate 13-acetate (PMA), also stimulate MT polymerization. Addition of colchicine (0.3 μM) eight hours after growth factor addition blocks stimulation of 3H-thymidine incorporation by thrombin, EGF, or PMA, suggesting that tubulin polymerization or subsequent events triggered by MT polymerization are required for cells to enter a proliferative cycle. Consistent with models for autoregulation of tubulin synthesis, thrombin, EGF, and PMA all increase tubulin synthesis 9 to 15 hr after growth factor addition, raising the possibility that the decrease in free tubulin and subsequent stimulation of tubulin synthesis is linked to progression of cells into a proliferative cycle. Colchicine addition to these cells also stimulates DNA synthesis, but colchicine-stimulated cells enter S phase 6 to 8 hr later than those stimulated by growth factors. This delayed stimulation may be related to the time required for degradation of tubulin- colchicine complexes below a critical level. These data suggest that regulation of cell proliferation may be linked to increased MT polymerization and the resulting decrease in free tubulin pools. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970230406
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Au+, Ag+ and Cu+ attachment to polybutadiene in laser desorption at 1064 nm (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 53-57 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Cu+, Ag+ and Au+ gas-phase ions have been found, in laser desorption time-of flight experiments, to attach efficiently to polybutadiene, a polymer containing no polar groups. The desorption and cation attachment were accomplished using the fundamental frequency of Nd:YAG laser, at a wavelength of 1064 nm, and supporting the samples on probe tips made of the appropriate metal. laser powers were in the range of 1.0-2.0 × 108 W/cm2. Time delays between the application of the laser pulse and the sampling of the resultant ion population were in the range 30-80 μs. The Au+ attachment is contrary to the reported findings from a laser desorption charge-exchange spectrum obtained from a gold surface by Kahr and Wilkins. The differences in the spectra are discussed in terms of the differences in the two experimental methods. Attachment by these ions could be useful in the laser desorption analysis of other polymer molecules, particularly those containing no polar groups.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070113
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Bimolecular reactions involving the radical site of the distonic ion ·CH2CH2CH2C≡O+ (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 392-399 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A systematic comparison of the reactivity of the γ-dictonic ion ·CH2CH2CH2C≡O+ to that of its even-electron analog, CH3CH2CH2C≡O+, and a related conventional radical cation, ionized cyclopentanone, was carried out using a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer. Each of the ions exhibits unique chemical reactivity. The conventional radical cation reacts with neutral reagents primarily by electron transfer. The even-electron acylium ion CH3CH2CH2C≡O+ is unreactive towards most of the neutral molecules studied; slow proton transfer is the only reaction observed with a few reagents. In sharp contrast to the behavior of these two ions, the distonic ion undergoes a variety of reactions with each neutral reagent. Most of these reactions involve a homolytic bond cleavage in the neutral reagent, leading to abstraction of an atom or a radical by the ion. Although reactions directly involving the charge site are not common for this ion, many of its reactions are likely to be catalyzed by the charge site. Initial bond formation at the charge site stabilizes the collision complex, extending its lifetime. This binding may also favorably position the neutral molecule for a subsequent reaction with the radical site of the ion. Accordingly, relatively facile radical abstraction reactions were observed for those reagents which react through a favorable six-membered transition state after bonding to the charge site. These neutral reagents react similarly, but at a slower rate, with the lower homolog, ·CH2CH2C≡O+, presumably because a six-membered transition state is not accessible in this case.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070516
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...