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  • 1
    Electronic Resource
    Electronic Resource
    Identification of defect centers in Hg1−xCdxTe using their energy level composition dependence (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 5279-5286 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have extended the Kobayashi, Sankey, and Dow [Phys. Rev. B 25, 6367 (1982)] theory of deep levels in Hg1−xCdxTe to include (vacancy, impurity) nearest-neighbor pairs. In qualitative agreement with the results obtained by these workers for isolated point defects, we find that the composition dependences (dE/dx) of the defect energy levels associated with such complexes depend on the site occupied by the impurity atom. Furthermore, we find that the composition dependences of some of the defect levels produced by such a complex are very different than the dE/dx of levels associated with the corresponding isolated point defects. We thus suggest that this theory can often be used as an aid in the identification of the defect center producing an observed energy level. In particular, it can be used to obtain site information about an observed level and, in favorable cases, to distinguish between levels produced by isolated point defects and those produced by complexes. As an example, we compare our theoretical predictions for the dE/dx of levels associated with (vacancy, impurity) pairs to the experimental slopes of the energy levels observed in deep level transient spectroscopy by Jones, Nair, and Polla [Appl. Phys. Lett. 39, 248 (1981)] and find that the theory lends support to these workers' interpretation of their data. In addition, we present new photoluminescence data on both a previously observed and identified acceptor and on an unknown center in Hg1−xCdxTe. As a further example of the usefulness of our theory, we compare the theoretical slopes of energy levels associated with (vacancy, impurity) pairs with the composition dependences of the defect levels extracted from the photoluminescence data. The results of both of the theoretical-experimental comparisons show that the theory can be used successfully, in conjunction with experimental data, to aid in the identification of the defect center which produces an observed energy level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334842
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  • 2
    Electronic Resource
    Electronic Resource
    Useful properties of the system matrix for a homogeneous anisotropic visco-elastic solid (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 97 (1989), S. 0 
    Details
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-246X.1989.tb00493.x
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  • 3
    Electronic Resource
    Electronic Resource
    Auto-Epitopes and Autoimmune Diseases (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 475 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb20856.x
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  • 4
    Electronic Resource
    Electronic Resource
    Differential survival of chaparral seedlings during the first summer drought after wildfire (1988)
    Springer
    Oecologia 76 (1988), S. 215-221 
    Details
    ISSN: 1432-1939
    Keywords: Chaparral ; Seedling establishment ; Water stress ; Drought ; Fire
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Big Pod Ceanothus (Ceanothus megacarpus) is an obligate seeder after fire; Laurel Sumac (Rhus laurina) is primarily a resprouter after fire. Both species commonly occur together in mixed stands and are dominant members of the coastal chaparral of southern California. We compared the mean survival of post-fire seedlings of each species during the first summer drought after fire and found C. megacarpus to have a mean survival of 54% while R. laurina had a mean survival of only 0.1%. Rooting dephs were similar between species but predawn water potentials and leaf temperatures were higher for R. laurina seedlings. Leaf temperatures for R. laurina reached a mean value of 46.8° C on hot, summer days, about 5° C higher than seedlings of C. megacarpus. By the end of the first growing season, 92% of all C. megacarpus seedlings had suffered herbivory compared to only 17% of all R. laurina seedlings. Herbivory did not appear to be the immediate cause of seedling mortality. Transect data indicated that full recovery of prefire species composition and density at our study site was likely but the mode of recovery was different for the species examined. R. laurina recovered primarily by sprouting, C. megacarpus totally by seedling establishment and a third species, Adenostoma fasciculatum (chamise), by a combination of sprouting and seedling establishment. We attribute the higher mortality of R. laurina seedlings to the greater sensitivity of its tissue to water stress. It may be that differential survival of shrub seedlings and differential modes of reestablishment after fire play an important role in maintaining species diversity in the chaparral communities of coastal, southern California.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379955
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  • 5
    Electronic Resource
    Electronic Resource
    Dispersed growth of Streptomyces in liquid culture (1989)
    Springer
    Applied microbiology and biotechnology 31 (1989), S. 272-277 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The study of the physiology of the filamentous bacterium Streptomyces is inhibited by its formation of mycelial pellets in liquid cultures. It is demonstrated that dispersed growth may be achieved by the addition of polymers to the culture medium. Uncharged polymers, such as polyethylene glycol, are relatively ineffective but polyanions such as agar, Carbopol and Junlon produce dispersed cultures when included in a defined growth medium at low concentrations. Junlon-containing media enable optical density measurements to be used to follow batch growth of Streptomyces. Improvements in both biomass yield and product yield of the pigmented antibiotic actinorhodin were found to result from the incorporation of Junlon into minimal medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00258408
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  • 6
    Electronic Resource
    Electronic Resource
    Knowledge-based systems for analytical chemistry (1986)
    Springer
    Microchimica acta 89 (1986), S. 163-185 
    Details
    ISSN: 1436-5073
    Keywords: knowledge-based systems ; first principles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Analytical chemists have made extensive use of computer technology, automating most analytical instruments, many analyses and reporting activities. We now need to expand the areas to which computers can be applied by addressing problems of greatly increased complexity. These problems fall into two general classes, the first class of problems are those thatcannot be solved using only first principle information and, the second class are those problems thatcan be solved using only first principles, but that are so complex that the traditional approach is often not cost effective. The discussion will center on how artificial intelligence technology (AI) can provide the means for using heuristics together with first principle information to solve instances of the first class of problems. The knowledge required to provide the solution is formulated as facts, rules (heuristics) and an inference engine. The same AI technology can also be used to refine specifications and provide cost effective solutions for very complex problems involving only first principle information. For this class of problems an AI work station can provide the software development conductive to rapid prototyping and specification refinement. Discussion of several expert systems will be used to describe the capabilities and features of rule-based systems. The strengths and weaknesses of one system, use of IR spectra for structure elucidation, will be examined in some detail. It is an expert system consisting of rule sets organized into logic trees, thus it will provide an opportunity to describe how the use of more advanced AI technology could further improve the program's performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01207315
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  • 7
    Electronic Resource
    Electronic Resource
    The estimation of the coulombic efficiency of zinc electrodeposition by measurement of current efficiencies at a rotating ring disc electrode (1986)
    Springer
    Journal of applied electrochemistry 16 (1986), S. 387-392 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The rotating ring disc electrode (RRDE) offers a simple method for the determination of the current efficiency (CE) of zinc electrodeposition in acidic zinc sulphate electrolytes. The hydrogen evolved during zinc deposition can be detected at the ring. This allows estimation of the current due to hydrogen formation at the disc and hence CE for electrodeposition of zinc can be calculated. Investigations of the conditions under which reliable measurements of CE can be obtained are described. A correlation between CE, determined using the RRDE, and the coulombic efficiency (QE), determined by weighing the zinc deposit obtained after 2 h electrodeposition at constant current, is established for a range of electrolyte compositions. It is suggested that measurement of CE at a Pt−Zn RRDE provides an efficient means of estimating QE for zinc electrolytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01008849
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  • 8
    Electronic Resource
    Electronic Resource
    Identification of optimum conditions for zinc electrowinning in high-purity synthetic electrolytes (1987)
    Springer
    Journal of applied electrochemistry 17 (1987), S. 453-462 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The optimum conditions for zinc electrowinning in synthetic acidic zinc sulphate electrolytes (0.8 M ZnSO4+1.07 M H2SO4) were determined using response surface statistical analysis. The coulombic efficiency (QE) was optimized with respect to temperature (T), current density (J) and electrode rotation rate (n). For an electrolyte prepared from AR zinc sulphate and Aristar sulphuric acid, containing trace lead and nickel, QE reached a maximum of 98.8% on a zinc substrate under the following conditions:T=50°C,J=500 A m−2,n=35s−1. For a very-high-purity electrolyte, prepared by dissolution of 99.9999% zinc in Aristar sulphuric acid, a maximum QE of 98.4% was predicted and obtained at:T≃61°C,J≃890 A m−2,n≃38s−1. Using a statistical response surface model calculated during the optimization process, QE contours giving an overall view of electrolyte performance were constructed. The QE responses were determined principally byT andJ, with significant interaction betweenn andJ orT andJ, depending on the impurity composition of the electrolyte. The model was also used to predict the QE response of the above electrolytes under conditions similar to industrial practice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01084118
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  • 9
    Electronic Resource
    Electronic Resource
    The electrodeposition of gallium from synthetic Bayer-process liquors (1988)
    Springer
    Journal of applied electrochemistry 18 (1988), S. 134-141 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Gallium was electrodeposited from a synthetic Bayer solution comprising 4.5m NaOH/0.2m Na2CO3/0.3m NaCl/1.7m Al(OH)3. Hydrogen evolution occurred in parallel with gallium deposition, the latter process being in part controlled by mass transfer and in part by the electron transfer step. Combined coulometric and voltammetric measurements allowed estimation of a diffusion coefficient for Ga (III) of 3.6×10−6 cm2 sec−1 at 40° C. The coulombic efficiency for gallium deposition was a function of current density, deposition time, electrode rotation rate, temperature and gallium concentration. Values of up to 11% were obtained on a copper electrode from a solution containing 3.2×10−3 m Ga (III). Heavy-metal impurities, such as iron and vanadium, usually found in these liquors, promote the hydrogen evolution reaction, completely inhibiting gallium production if present above certain critical concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01016217
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of certain impurities on zinc electrowinning in high-purity synthetic solutions (1988)
    Springer
    Journal of applied electrochemistry 18 (1988), S. 583-589 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The individual effects of lead, copper, nickel, cobalt and antimony on zinc electrowinning were evaluated by measurements in high-purity synthetic solutions, free from additives. The coulombic efficiency (QE) of zinc electrodeposition was determined over 2h under mass transfer-controlled conditions at a temperature of 35°C and a current density of 400 A m−2 in a solution of 0.8 M ZnSO4+1.07 M H2SO4. Antimony had a very detrimental effect on QE causing decrease of ∼ 5 and 50% at 4 and 14 μg l−1, respectively. Antimony also exerted a strong grain-refining effect and changed the deposit orientation from random to (112) to (004) with increasing concentration. Lead had a small beneficial effect on QE at the electrode rotation rate employed (20 s−1). It also exerted a grain-refining effect and changed the deposit orientation from random to (102), (103), (104), to strong basal (004), (002) with increasing concentration. Copper, nickel and cobalt had minor effects on QE, with reductions at 5 mg l−1 of 0.8, 0.3 and 0.3%, respectively. The effects of copper on morphology and orientation were very concentration dependent, but with a general trend towards grain-refining and random orientation. Nickel promoted coarse-grained deposits and changed the orientation from random to (114), (102) to (204), (102) with increasing concentration. Cobalt had the least effect on the morphology of the deposit, although it gradually increased the basal plane orientation with increasing concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01022254
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