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  • 1
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    Iodide management in formamidinium-lead-halide-based perovskite layers for efficient solar cells (2017)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2017-06-30
    Description: The formation of a dense and uniform thin layer on the substrates is crucial for the fabrication of high-performance perovskite solar cells (PSCs) containing formamidinium with multiple cations and mixed halide anions. The concentration of defect states, which reduce a cell’s performance by decreasing the open-circuit voltage and short-circuit current density, needs to be as low as possible. We show that the introduction of additional iodide ions into the organic cation solution, which are used to form the perovskite layers through an intramolecular exchanging process, decreases the concentration of deep-level defects. The defect-engineered thin perovskite layers enable the fabrication of PSCs with a certified power conversion efficiency of 22.1% in small cells and 19.7% in 1-square-centimeter cells.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
    Electronic Resource
    Electronic Resource
    Activities of carboxylating enzymes in the CAM species Opuntia ficus-indica grown under current and elevated CO2 concentrations (1994)
    Springer
    Photosynthesis research 40 (1994), S. 223-229 
    Details
    ISSN: 1573-5079
    Keywords: Crassulacean acid metabolism ; CO2 enrichment ; Opuntia ficus-indica ; PEPCase ; Rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Responses of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPCase) to an elevated atmospheric CO2 concentration were determined along with net CO2 uptake rates for the Crassulacean acid metabolism species Opuntia ficus-indica growing in open-top chambers. During the spring 13 months after planting, total daily net CO2 uptake of basal and first-order daughter cladodes was 28% higher at 720 than at 360 μl CO2 l-1. The enhancement, caused mainly by higher CO2 assimilation during the early part of the night, was also observed during late summer (5 months after planting) and the following winter. The activities of Rubisco and PEPCase measured in vitro were both lower at the elevated CO2 concentration, particularly under the more favorable growth conditions in the spring and late summer. Enzyme activity in second-order daughter cladodes increased with cladode age, becoming maximal at 6 to 10 days. The effect ofelevated CO2 on Rubisco and PEPCase activity declined with decreasing irradiance, especially for Rubisco. Throughout the 13-month observation period, O. ficus-indica thus showed increased CO2 uptake when the atmospheric CO2 concentration was doubled despite lower activities of both carboxylating enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034772
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  • 3
    Electronic Resource
    Electronic Resource
    Recovery of photosynthetic reactions after high-temperature treatments of a heat-tolerant cactus (1988)
    Springer
    Photosynthesis research 18 (1988), S. 277-286 
    Details
    ISSN: 1573-5079
    Keywords: CO2 uptake ; high-temperature acclimation ; Opuntia ficus-indica ; photosystems I and II ; whole chain electron transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Inhibition and recovery of net CO2 uptake and three photosynthetic electron transport reactions as well as plant survival following high-temperature treatments were investigated for Opuntia ficus-indica. For plants maintained at 30°C/20°C day/night air temperatures, treatment at 60°C for 1 h irreversibly inhibited net CO2 uptake and photosynthetic electron transport, resulting in plant death in about 60 days. When a plant maintained at 30°C/20°C was treated at 55°C for 1 h, net CO2 uptake was completely inhibited 1 d after the treatment but fully recovered in 60 d. Differential inactivation of photosystem (PS) I, PSII, and whole chain electron transport activities occurred; PSI was the most tolerant of 55°C and took the least time (45 d) for total recovery. All 30°C/20°C plants survived a 1-h treatment at 55°C, although some pale green areas were observed on the cladode surfaces. In contrast to growing at 30°C/20°C, plants acclimated to 45°C/35°C survived 60°C for 1 h without showing any necrotic or pale green areas on the cladode surfaces. When such a plant was transferred to 30°C/20°C following the high-temperature treatment, recovery in net CO2 uptake began in 1 d and progressed to complete recovery by 30 d. Growth temperatures thus influence the possibility for recovery of photosynthetic reactions and ultimately the survival of O. ficus-indica following a high-temperature exposure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034832
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  • 4
    Electronic Resource
    Electronic Resource
    Batch fermentation kinetics of sugar beet molasses by Zymomonas mobilis (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 304-313 
    Details
    ISSN: 0006-3592
    Keywords: Zymomonas mobilis ; molasses ; fermentation ; ethanol ; osmolality ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new osmotolerant mutant strain of Zymomonas mobilis was successfully used for ethanol production from beet molasses. Addition of magnesium sulfate to hydrolyzed molasses allowed repeated growth without the need of yeast extract addition. The kinetics and yields parameters of fermentation on media with different molasses concentrations were calculated. The anabolic parameters (specific growth rate, μ, and biomass yield, YX/S) were inhibited at elevated molasses concentrations while the catabolic parameters (specific ethanol productivity, qp, and ethanol yield, Yp/s) were not significantly affected. In addition to ethanol and substrate inhibition, osmotic pressure effects can explain the observed results.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380312
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  • 5
    Electronic Resource
    Electronic Resource
    Production of penicillin in a fluidized-bed bioreactor using a carrier-supported mycelial growth (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1838-1844 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A carrier-supported mycelial growth of Penicillium chrysogenum was applied to penicillin fermentation system using celite as a support material. Hyphal growth through the pore matrices of the material showed strong anchorages and provided highly stable biofilm growth. With bioparticles developed in such a manner, both cell growth and penicillin production were observed to increase significantly compared to the conventional dispersed filamentous cultures. Maximum values of specific penicillin production rate were found to be constant regardless of the growth form. A three-phase fluidized-bed fermentor was designed and tested for penicillin production using the bioparticles. Two modes of operation, semicontinuous and repeated fed batch, of the fermentor were tried. It was noted that the overgrowth of free mycelia and the development of fluffy loose bioparticles caused poor mixing and made the fermentor operation quite difficult. Control of the bioparticle size and the extension of production phase were therefore considered important to maintain the reactor productivity at a desired level. From the results of repeated fed-batch operation it was found that the control of bioparticle size could be successfully achieved by phosphate-limiting culture condition. Penicillin production under this condition was also observed to be maintained at a high level (about 80% of the maximum) for at least 1 month.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260281211
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  • 6
    Electronic Resource
    Electronic Resource
    Importance of spore mutants for fed-batch and continuous fermentation of Bacillus subtilis (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 696-702 
    Details
    ISSN: 0006-3592
    Keywords: Bacillis subtilis ; spore mutant ; fed-batch ; continuous culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To alleviate plasmid instability and to prolong the production phase of subtilisin, integrable plasmid and spore mutants are used. Compared with batch-type shake flask cultures, spore mutants' ability to produce subtilisin can be well pronounced in fed-batch and continuous cultures. Hence, the two culture methods make it possible to identify the peculiar characteristics of the spore mutants unobtainable in batch culture. Spore mutants can enhance subtilisin productivity and prolong subtilisin production time in fed-batch culture as well as enable us to use very low dilution rates (〈0.1 h-1) without losing productivity in continuous culture, thereby improving the conversion yield of the nitrogen source. At 0.05 h-1 the spollG mutant of Bacillus subtilis DB104 (Δnpr Δapr) (Emr) spollG (Bimr):: pMK101 (Cmr) showed a subtilisin yield about ten times higher than that from wild-type DB104 (Δnpr Δapr)::pMK101 (Cmr). © 1995 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260470610
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  • 7
    Electronic Resource
    Electronic Resource
    Einfluß der Korngröße auf mechanische Eigenschaften und den ungeschmierten reversierenden Gleitverschleiß von Al2O3-Keramik (1992)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 23 (1992), S. 329-338 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Influence of grain size on mechanical properties and dry oscillating sliding wear of Al2O3-ceramicsSpecimens with average grain sizes varying between about 0.8 μm and 12 μm were produced by cold isostatic pressing of high purity Al2O3-powder followed by sintering between 1300°C and 1700°C. Hardness, Young's modulus, bending strength and fracture toughness were measured as a function of average grain sizes. Tribological tests were carried out on the different microstructures at normal laboratory air and room temperature by using a ring-on-block tribometer.Experimental results showed the dependence of mechanical properties on grain size, hardness and bending strength obeying a Hall-Petch type relation, approximately. Coefficient of friction was relatively independent of grain size under the test conditions used. However, wear intensity increased substantially if a critical grain size was surpassed. This was due to a change in mechanisms of material removal which was confirmed by scanning electron microscopical studies of the worn surfaces.
    Notes: Aus hochreinem Al2O3-Pulver wurden durch kaltisostatisches Pressen und Variation der Sintertemperatur zwischen 1300°C und 1700°C Formkörper mit unterschiedlichen mittleren Korngrößen zwischen etwa 0,8 und 12 μm hergestellt. Untersucht wurde der Einfluß der Korngröße auf mechanische und tribologische Eigen-schaften.Die Ergebnisse zeigten, daß mechanische Eigenschaften wie Härte, E-Modul, Biegebruchfestigkeit und Bruchzähigkeit von der Korngröße bzw. den Sintertemperaturen abhingen, wobei im Fall der Härte und Bruchfestigkeit näiherungsweise eine Hall-Peteh-Beziehung vorlag. Während die Reibungszahl relativ unabhängig von der Korngröße war, trat in der Verschleißintensität aufgrund geänderter Mechanismen ein starker Anstieg mit zunchmender Korngröße auf. Rasterelektronenmikroskopische Untersuchungen zeigten, daß der Verschleiß durch plastische Verformung, Mikrobruch, Kornfragmentierung und Deckschichten beeinflußt wurde.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19920230909
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  • 8
    Electronic Resource
    Electronic Resource
    Error in the propagation of error formula (1980)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 26 (1980), S. 168-170 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690260132
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  • 9
    Electronic Resource
    Electronic Resource
    Letters to the editor (1981)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 527-528 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690270332
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  • 10
    Electronic Resource
    Electronic Resource
    Rheological study on poly-D(-)(3-hydroxybutyrate) and its blends with poly(ethylene oxide) (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1636-1642 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Notes: Aspects of thermal, morphological, and rheological properties of biodegradable poly-D(-)(3-hydeoxybutyrate) (PHB) blended with poly(ethylene oxide) (PEO) have been studied. Thermal properties and morphology of the blends were examined by scanning electron microscopy and differential scanning calorimetry, respectively. A rotational theometer with parallel plate geometry was also adopted to investigate the rheological properties of these blends. In addition, dynamic ciscoelasticity was measured by a Rheovibron as functions of time and temperature. From these measurements, PHB and PEO were observed to be miscible in the melt state. In the case of the blend systen 80/20 PHB/PEO by weight, the vacant domains of the PHB were filled with PEO particles, and this morphological state enhanced the rheological properties. Furthermore, PHB and its blends were found to have high crystallinities, but to have unstable thermal behavior about Tm.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760352010
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