Carica papaya latex-catalyzed synthesis of structured triacylglycerols

One impediment to the industrial use of enzymes in fat and oil transformations is the higher cost often associated with an enzymatic process compared with the corresponding chemical process. Processes that utilize plant enzymes, however, may have advantages because of their lower cost and ready availability. One example of such a plant-derived enzyme is Carica papaya latex (CPL), the principal source of the protease papain. Recently, it has been shown that this latex also catalyzes the lipolysis of triacylglycerols and that this latex lipase has a selectivity for short-chain acyl groups as well as a 1,3-glycerol selectivity. These selectivities can be used in the synthesis of structured triacylglycerols. In this paper we describe the utility of CPL in lipase-catalyzed reactions, specifically the synthesis of low-calorie triacylglycerol analogs. Presented in part at the American Oil Chemists’ Society’s 88th Annual Meeting & Expo, Seattle, WA, May 1997.     

Microcrystalline silicon solar cell using p-a-Si:H window layer deposited by photo-CVD method

A p-a-Si:H layer, deposited by a photo-assisted chemical vapor deposition (photo-CVD) method, was adopted as the window layer of a hydrogenated microcrystalline silicon (μc-Si:H) solar cell instead of the conventional p-μc-Si:H layer. We verified the usefulness of p-a-Si:H for the p-layer of the μc-Si:H solar cell by applying it to SnO₂-coated glass substrate. It was found that the quantum efficiency (QE) characteristics and solar cell performance strongly depend on the p-a-Si:H layer thicknesses. We applied boron-doped nanocrystalline silion (nc-Si:H) p/i buffer layers to μc-Si:H solar cells and investigated the correlation of the p/i buffer layer B₂H₆ flow rate and solar cell performance. When the B₂H₆ flow rate was 0.2 sccm, there was a little improvement in fill factor (FF), but the other parameters became poor as the B₂H₆ flow rate increased. This is because the conductivity of the buffer layer decreases as the B₂H₆ flow rate increases above appropriate values. A μc-Si:H single-junction solar cell with ZnO/Ag back reflector with an efficiency of 7.76% has been prepared.     

热管技术及其在加氢反应炉上的应用

介绍了热管技术的先进性和可靠性,并介绍了热管技术在高压加氢装置加氢反应炉上的使用情况。加氢反应炉空气预热系统改用热管预热器后,炉子热效率提高了约3%。     

Characterization of undoped μc-SiO:H films prepared from (SiH4+CO2+H2)-plasma in RF glow discharge

Undoped hydrogenated microcrystalline silicon oxygen alloy films (μc-SiO:H) have been prepared from (SiH₄+CO₂+H₂)-plasma in RF glow discharge at a high H₂ dilution, moderately high RF power and substrate temperature. A detailed characterization of the films has been done by electrical, optical as well as structural studies, e.g., IR absorption spectroscopy, Raman scattering and transmission electron microscopy. The presence of a very small amount of oxygen induces the crystallization process, which fails to sustain at a higher oxygen dilution. At higher deposition temperature and in improved μc-network H content reduces, however, O incorporation is favoured. Sharp crystallographic rings in the electron diffraction pattern identify several definite planes of c-Si and no such crystal planes from c-SiO_X is detected.     

氢化腈类橡胶(HNBR)中的残余不饱和度碘值法分析

将氢化腈类橡胶( HNBR) HNBR试样溶于氯仿中,加入过量的Wijs’试剂后,静置适当的时间(2 h)使其与HNBR中的残留不饱和物反应完全.然后用碘化钾还原过量的Wijs’试剂,最后用硫代硫酸钠标准滴定溶液滴定溶液中的游离碘,计算碘值(不饱和度).     

Study on hydrogenated silicon nitride for application of high efficiency crystalline silicon solar cells

The hydrogenated silicon nitride films (SiN_x:H) deposited by plasma enhanced chemical vapor deposition (PECVD) technique is commonly used as an antireflection coating as well as surface passivating layer of crystalline silicon solar cells. The refractive indices of SiN_x:H films could be changed by varying the growth gas ratio R(=NH₃/SiH₄+NH₃) and annealing temperature. For optimum SiN_x:H film, the optical and chemical characterization tools by varying the film deposition and annealing condition were employed in this study. Metal-insulator-semiconductor (MIS) devices were fabricated using SiN_x:H as an insulator layer and they were subjected to capacitance-voltage (C-V) and current-voltage (I-V) measurements for electrical characterization. The effect of rapid thermal annealing (RTA) on the surface passivation as well as antireflection properties of the SiN_x:H films deposited at various process conditions were also investigated for the fabrication of low cost and high efficiency silicon solar cells.     

Efficient hydrogen storage in defective graphene and its mechanical stability: A combined density functional theory and molecular dynamics simulation study

A combined density functional theory and molecular dynamics approach is employed to study modifications of graphene at atomistic level for better H₂ storage. The study reveals H₂ desorption from hydrogenated defective graphene structure, V₂₂₂, to be exothermic. H₂ adsorption and desorption processes are found to be more reversible for V₂₂₂ as compared to pristine graphene. Our study shows that V₂₂₂ undergoes brittle fracture under tensile loading similar to the case of pristine graphene. The tensile strength of V₂₂₂ shows slight reduction with respect to their pristine counterpart, which is attributed to the transition of sp² to sp³-like hybridization. The study also shows that the V₂₂₂ structure is mechanically more stable than the defective graphene structure without chemically adsorbed hydrogen atoms. The current fundamental study, thus, reveals the efficient recovery mechanism of adsorbed hydrogen from V₂₂₂ and paves the way for the engineering of structural defects in graphene for H₂ storage.     

The structure and adhesion of hydrogenated amorphous carbon (a-C:H) films synthesized on CoCrMo alloy by plasma immersion ion implantation and deposition at different flow ratios of acetylene to argon

Hydrogenated amorphous carbon (a-C:H) film is deposited on CoCrMo alloy by plasma immersion ion implantation and deposition (PIII-D) at different flow ratios of acetylene to argon (C₂H₂/Ar). The results show that Ar fraction in the C₂H₂-Ar gas mixture has an important effect on the structure and the adhesion of the a-C:H films. When Ar fraction in the C₂H₂-Ar gas mixture is less than 50%, the fabricated a-C:H film composition transfer from graphite-like to diamond-like which contains higher sp³ binding thanks to Ar ion bombardment, and the adhesion strength decreased with the increment of Ar fraction. But when Ar fraction in the C₂H₂-Ar gas mixture is beyond 50%, the fabricated film contains more sp² bonding for thermally driven and exhibits higher adhesion strength with the increment of the Ar fraction.     

Characterization of Plasma Enhanced Chemical Vapor Deposition-Physical Vapor Deposition transparent deposits on textiles to trigger various antimicrobial properties to food industry textiles

Textiles for the food industry were treated with an original deposition technique based on a combination of Plasma Enhanced Chemical Vapor Deposition and Physical Vapor Deposition to obtain nanometer size silver clusters incorporated into a SiOCH matrix. The optimization of plasma deposition parameters (gas mixture, pressure, and power) was focused on textile transparency and antimicrobial properties and was based on the study of both surface and depth composition (X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), as well as Transmission Electron Microscopy, Atomic Force Microscopy, SIMS depth profiling and XPS depth profiling on treated glass slides). Deposition conditions were identified in order to obtain a variable and controlled quantity of ~ 10 nm size silver particles at the surface and inside of coatings exhibiting acceptable transparency properties. Microbiological characterization indicated that the surface variable silver content as calculated from XPS and ToF-SIMS data directly influences the level of antimicrobial activity.     

Characterization of pulsed laser deposited hydrogenated amorphous silicon films by spectroscopic ellipsometry

The wide absorption band of hydrogenated amorphous silicon (a-Si:H) is being realized as a key component of solar cells on glass. In this study, a-Si:H films were prepared by reactive pulsed laser deposition onto silicon and glass substrates. Ellipsometry showed that the optical properties of the films are effectively independent on the choice of substrate. According to the optical properties, the character of the films changes from amorphous silicon to dielectric as the hydrogen background pressure increases from 0 to 25 Pa. This observation was attributed to oxygen incorporation indicated by Rutherford Backscattering Spectrometry. Furthermore, a refractive index gradient in depth was revealed, which was attributed to the oxygen concentration gradient.