Influence of the composition of vacuum residues as oxidation feedstock on the performance characteristics of road asphalts

The hydrocarbon-group composition of short residues having different values of the specific viscosity was studied. The influence of the hydrocarbon-group composition of short residues from West Siberian crude oils on the properties of petroleum air-blown road asphalts was examined.     

Accelerated development of CuSbS2 thin film photovoltaic device prototypes

Development of alternative thin film photovoltaic technologies is an important research topic because of the potential of low‐cost, high‐efficiency solar cells to produce terawatt levels of clean power. However, this development of unexplored yet promising absorbers can be hindered by complications that arise during solar cell fabrication. Here, a high‐throughput combinatorial method is applied to accelerate development of photovoltaic devices, in this case, using the novel CuSbS₂ absorber via a newly developed three‐stage self‐regulated growth process to control absorber purity and orientation. Photovoltaic performance of the absorber, using the typical substrate CuIn_xGa_{1 − x}Se₂ (CIGS) device architecture, is explored as a function of absorber quality and thickness using a variety of back contacts. This study yields CuSbS₂ device prototypes with ~1% conversion efficiency, suggesting that the optimal CuSbS₂ device fabrication parameters and contact selection criteria are quite different than for CIGS, despite the similarity of these two absorbers. The CuSbS₂ device efficiency is at present limited by low short‐circuit current because of bulk recombination related to defects, and a small open‐circuit voltage because of a theoretically predicted cliff‐type conduction band offset between CuSbS₂ and CdS. Overall, these results illustrate both the potential and limits of combinatorial methods to accelerate the development of thin film photovoltaic devices using novel absorbers. Copyright © 2016 John Wiley & Sons, Ltd.     

Enhanced Electron Mobility Due to Dopant‐Defect Pairing in Conductive ZnMgO

The increase of the band gap in Zn_1‐xMg_xO alloys with added Mg facilitates tunable control of the conduction band alignment and the Fermi‐level position in oxide‐heterostructures. However, the maximal conductivity achievable by doping decreases considerably at higher Mg compositions, which limits practical application as a wide‐gap transparent conductive oxide. In this work, first‐principles calculations and material synthesis and characterization are combined to show that the leading cause of the conductivity decrease is the increased formation of acceptor‐like compensating intrinsic defects, such as zinc vacancies (V_Zn), which reduce the free electron concentration and decrease the mobility through ionized impurity scattering. Following the expectation that non‐equilibrium deposition techniques should create a more random distribution of oppositely charged dopants and defects compared to the thermodynamic limit, the paring between dopant Ga_Zn and intrinsic defects V_Zn is studied as a means to reduce the ionized impurity scattering. Indeed, the post‐deposition annealing of Ga‐doped Zn_0.7Mg_0.3O films grown by pulsed laser deposition increases the mobility by 50% resulting in a conductivity as high as σ = 475 S cm^‐1.     

Use of gas chromatography to monitor product quality in dewaxing

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 4, pp. 37–38, April, 1988.     

Prediction of storage life of hydraulic oils on the basis of accelerated climatic tests

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 12–14, February, 1994.     

A one-dimensional numerical model of acoustic wave propagation in a multilayered structure of a resistance spot weld

A one-dimensional model of acoustic wave propagation in a multilayered structure of a spot weld is developed. The inhomogeneity of the material properties due to the thermal inhomogeneity is included in the equation of motion. The model enables us to deal with arbitrary spatial distributions of Lamé constants and density. The model allows analysis of travel time, multiple reflections, and interference in a given geometry. Use of this model could provide information to help predict behavior of the waves in the transmission (reflection) mode at different plate thicknesses and welding settings.     

Solvent-free derivatization of pristine multi-walled carbon nanotubes with amines

We performed direct solvent-free amination of multi-walled carbon nanotubes (MWCNTs) with nonylamine, dodecylamine, octadecylamine, 4-phenylbutylamine and 1,8-ocanediamine at a temperature of 150-170 degrees C and reduced pressure. Thermogravimetric analysis and temperature-programmed desorption-mass spectrometry revealed that a major amine fraction decomposes in a temperature interval of 250-500 degrees C, thus existing on multi-walled carbon nanotubes as chemically bonded species; a minor amine fraction was found in physisorbed form. The new derivatization technique combines simplicity in implementation and attractive features of "green" chemistry. It requires no additional chemical activation, but thermal activation instead; it is relatively fast since it can be completed in about 2 h; the high temperature allows one to spontaneously remove excess amine from the nanotube and minimize the possibility of physical adsorption; there is no need to use an (organic) solvent medium. In the case of diamines (represented in this study by 1,8-ocanediamine), the functional groups introduced can be potentially used as chemical linkers for anchoring metal complexes and nanoparticles to multi-walled carbon nanotubes, for adsorption and concentration of trace metal ions.     

LanV, a bifunctional enzyme: aromatase and ketoreductase during landomycin A biosynthesis

LanV is involved in the biosynthesis of landomycin A. The exact function of this enzyme was elucidated with combinatorial biosynthesis by using Streptomyces fradiae mutants that produce urdamycin A. After expression of lanV in S. fradiae DeltaurdM, which is a mutant that accumulates rabelomycin, urdamycinon B and urdamycin B were found to be produced by the strain. This result indicates that LanV is involved in the 6-ketoreduction of the angucycline core, which preceeds a 5,6-dehydration reaction. 9-C-D-Olivosyltetrangulol was also produced by this strain; this demonstrates that LanV catalyses the aromatization of ring A of the angucycline structure. Coexpression of lanV and lanGT2 in S. fradiae AO, a mutant that lacks all four urdamycin glycosyltransferases, resulted in the production of tetrangulol and the glycoside landomycin H, both of which have an aromatic ring A. As glycosylated angucyclines were not observed after expression of lanGT2 in the absence of lanV, we conclude that LanGT2 needs an aromatized ring A for substrate recognition.     

Virulence and antifungal susceptibility of microsatellite genotypes of Candida albicans from superficial and deep locations

A set of 185 strains of Candida albicans from patients with vulvovaginal candidiasis (VVC) and from non-VVC clinical sources in southwest China was analysed. Strains were subjected to genotyping using CAI microsatellite typing and amplification of an intron-containing region of the 25S rRNA gene. Microsatellite genotypes of strains from non-VVC sources showed high polymorphism, whereas those of VVC were dominated by few, closely similar genotypes. However, among non-VVC strains, two genotypes were particularly prevalent in patients with lung cancer. 25S rDNA genotype A was dominant in VVC sources (86.7%), whereas genotypes A, B, and C were rather evenly distributed among non-VVC sources; known genotypes D and E were not found. In an experimental mouse model, isolates from lung cancer and AIDS patients proved to have higher virulence than VVC strains. Among 156 mice infected with C. albicans, 19 developed non-invasive urothelial carcinoma. No correlation could be established between parameters of virulence, source of infection, and incidence of carcinoma. C. albicans strains from VVC were less susceptible to itraconazole than the strains from non-VVC sources, whereas there was small difference in antifungal susceptibility between different 25S rDNA genotypes of C. albicans tested against amphotericin B, itraconazole, fluconazole, and flucytosine.     

Development of new dominant selectable markers for the nonconventional yeasts Ogataea polymorpha and Candida famata

Nonconventional yeast Candida famata and Ogataea polymorpha are interesting organisms for basic and applied studies. O. polymorpha is methylotrophic thermotolerant yeast capable of xylose alcoholic fermentation whereas C. famata is capable of riboflavin overproduction. Still, the new tools for molecular research of these species are needed. The aim of this study was to develop the new dominant selective markers for C. famata and O. polymorpha usable in metabolic engineering experiments. In this work, the BSD gene from Aspergillus terreus coding for blasticidin S deaminase, O. polymorpha AUR1 gene required for sphingolipid synthesis and IMH3 gene, which encodes IMP dehydrogenase, were tested as the new dominant selective marker genes. Our results showed that AUR1 and IMH3 genes could be used as dominant selective markers for O. polymorpha with frequencies of transformation of 40 and 20 transformants per microgram of DNA, respectively. The IMH3 gene was successfully used as the marker for construction of O. polymorpha strains with increased ethanol production from xylose due to overexpression of TAL1, TKL1 and AOX1 genes. The BSD gene from A. terreus, conferring resistance to blasticidin, was found to be efficient for selection of C. famata transformants.