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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
    Publikationsdatum: 2017-06-30
    Beschreibung: 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.
    Schlagwort(e): Chemistry
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Geologie und Paläontologie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): CO2 uptake ; high-temperature acclimation ; Opuntia ficus-indica ; photosystems I and II ; whole chain electron transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00034832
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  • 3
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Crassulacean acid metabolism ; CO2 enrichment ; Opuntia ficus-indica ; PEPCase ; Rubisco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00034772
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Beschreibung / Inhaltsverzeichnis: 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.
    Notizen: 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.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mawe.19920230909
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Application of extracorporeal shock wave lithotripter (ECSWL) in orthopaedics. III. In Vitro and In Vivo studiesPart of this work was presented to the Society for Biomaterials and Orthopedic Research Society annual meetings. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 2 (1991), S. 171-181 
    Details
    ISSN: 1045-4861
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The present study was conducted to compare the push-out strength of the treated and control samples obtained after implantation of intramedullary rod in canine femurs with bone cement to simulate the femoral stem implantation for 2 weeks, 3 and 6 months. Contralateral femur served as control. The result showed a significant decrease in push-out interfacial strength after shock wave treatment (average 48.4% decrease compared with control, p 〈 0.0001) which is similar to the in vitro results. There was no significant difference if the shock treatment was applied and left for 2 weeks or 4 weeks compared to the ones tested immediately after sacrifice. There were some soft tissue damage immediately following shock treatment in the focal area but this returned to normal in 2 weeks. Human cadaveric femoral bones and the canine bone (the dosage level was higher for the human bone than canine). The number of impacts used to extract the bone cement plug out of a human femur segment (5-cm long) decreased about 68% at 23 and 25 kV treatment power level. These preliminary studies indicate that the shock wave can be utilized to reduce the interfacial strength of the bone and bone cement although more studies are needed to assess its efficacy in terms of cost, long-term effect on patients and the exact mechanism of the loosening before this technique can be used clinically.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jab.770020305
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  • 6
    Digitale Medien
    Digitale Medien
    Application of extracorporeal shock wave lithotripter (ECSWL) in orthopaedics. II. Dose-response and pressure distribution measurements (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 2 (1991), S. 161-170 
    Details
    ISSN: 1045-4861
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: In order to apply the extracorporeal shock wave lithotripter (ECWSL) technique to the loosening of the bone-cement interface for the extraction of the cement during revision arthroplasty it is essential to know the dose-response characteristics. The present study shows that the number of shocks needed to break the interface between a 2- and 6-mm-thick bovine femoral bone and bone cement is similar to the fatigue behavior of a material, that is, Log(N) = C(kV) + D, where N is the number of shock impulses, kV is the power setting of the lithotripter machine in kilovolts, and C and D are constants. Iso-pressure distribution of the traveling shock wave front through a simulated bone in a Plexiglass® tube using Fuji® pressure film showed quantitative pressure contours from which one can understand the effective area of shock wave and its distribution. The most effective area of the shock wave was about 1.5 cm in diameter at 23 and 25 kV with pressure at least 7.0 MPa which is more than sufficient to break the bone-cement interface in tension.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jab.770020304
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  • 7
    Digitale Medien
    Digitale Medien
    Application of extracorporeal shock wave lithotripter (ECSWL) in orthopedics. I. Foundations and overviewParts of this paper were presented at the Society for Biomaterials and Orthopedic Research Society Annual meetings. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 2 (1991), S. 115-126 
    Details
    ISSN: 1045-4861
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: In this paper we have reviewed the feasibility of using a shock wave lithotripter to loosen the interface between the bone and acrylic bone cement for revision arthroplasty. We have reviewed the physics of shock wave and its applications in medicine, especially its interaction with tissues. The calculations show that the energy is greatly reduced at the interface both in the soft tissue-bone interface and cement-bone interface. On the other hand, a tensile and compressive pressure can be operated at the cement-bone interface that can cause the interface to break if the pressure exceeds the tensile strength of the cement-bone interface.Subsequent papers will deal with in vitro and in vivo application of the shock wave in the treatment of the cement-bone interface in order to weaken it and consequently for easier extraction of bone cement from the intramedullary canal.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jab.770020207
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  • 8
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: 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.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760352010
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  • 9
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: 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.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260281211
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  • 10
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Zymomonas mobilis ; molasses ; fermentation ; ethanol ; osmolality ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: 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.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260380312
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