Self-assembled lamellar MoS2, SnS2 and SiO2 semiconducting polymer nanocomposites

Lamellar nanocomposites based on semiconducting polymers incorporated into layered inorganic matrices are prepared by the co-assembly of organic and inorganic precursors. Semiconducting polymer-incorporated silica is prepared by introducing the semiconducting polymers into a tetrahydrofuran (THF)/water homogeneous sol solution containing silica precursor species and a surface-active agent. Semiconducting polymer-incorporated MoS(2) and SnS(2) are prepared by Li intercalation into the inorganic compound, exfoliation and restack in the presence of the semiconducting polymer. All lamellar nanocomposite films are organized in domains aligned parallel to the substrate surface plane. The incorporated polymers maintain their semiconducting properties, as evident from their optical absorption and photoluminescence spectra. The optoelectronic properties of the nanocomposites depend on the properties of both the inorganic host and the incorporated guest polymer as demonstrated by integrating the nanocomposite films into light-emitting diodes. Devices based on polymer-incorporated silica and polymer-incorporated MoS(2) show no diode behaviour and no light emission due to the insulating and metallic properties of the silica and MoS(2) hosts. In contrast, diode performance and electroluminescence are obtained from devices based on semiconducting polymer-incorporated semiconducting SnS(2), demonstrating that judicious selection of the composite components in combination with the optimization of material synthesis conditions allows new hierarchical structures to be tailored for electronic and optoelectronic applications.     

Sonochemical formation of metal sponges

A novel sonochemical method for formation of mesoporous metal sponges is developed. Systematic investigation of ultrasound effects on various types of metal particles reveals the cavitation-induced oxidation of metal surface and etching of metal matrix as main factors in the ultrasound-driven metal modification. Beyond the specific examples, the findings provide guidelines for expansion of the concept towards a broad variety of metal systems and allow development of the sonochemical approaches to manipulation of the metal surface and inner structure.     

Revealing the Origin of Polycyclic Aromatic Hydrocarbons in an Urban Snowpack

Polyciclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in urban atmosphere. Several PAHs are known carcinogens or are the precursors to carcinogenic daughter compounds. Understanding the contributions of various PAH emission sources is critical to appropriately managing PAH levels in the environment. The sources of PAHs to urban snowpack in Shelekhov city, Eastern Siberia, characterized by extremely high levels of PAH accumulation in snow were determined by using end-member mixing approach. The best potential to distinguish PAH emission sources is exhibited by ratios of PAH pairs of the principal mass 228, 252, and 276. The ratios of PAH pairs were used as tracers of end-member PAH sources. The contributions of sources were calculated using systems of linear equations. The results obtained using ratios of PAH pairs were compared with those obtained using molecular diagnostic ratios. It was shown that the results obtained using diagnostic ratios as tracers are less reliable than the results obtained using the ratios of the sums of PAHs.     

Relationship of the aromatic structural types in vacuum gas oil to empirical correlations based on bulk properties

Five empirical methods toestimate the content of aromatic, naphthenic, and paraffinic carbon and hydrogen content and the bulk properties were tested for prediction of aromatic structures content of 95 vacuum gas oils. The density demonstrated the highest correlation with the aromatic structures content among all other studied bulk properties and empirical parameters. The aromatic structures content could be predicted by a second order power law dependence on density with accuracy commensurable with the reproducibility of SARA analysis. The poly-nuclear aromatic structures content was also found to depend on the density and can be expressed by a linear function.     

Impact of feed properties on gasoline olefin content in the fluid catalytic cracking

Eight vacuum gas oils (VGOs) having different hydrocarbon composition and different distillation characteristics were cracked in a laboratory fluid catalytic cracking (FCC) advanced cracking equipment (ACE) unit. The experimental results showed that FCC VGO feedstock reactivity correlates with the content of saturates plus light aromatics, and with the content of nitrogen. The FCC gasoline olefin content was found to depend on T_50% and saturate content of the FCC VGO feedstock. The results from a commercial FCC unit that processes a hydrotreated straight-run VGO and a VGO from ebullated bed residue H-Oil hydrocracker confirmed the results from the laboratory FCC ACE unit showing that reducing T_50% and increasing saturate content of the FCC feedstock leads to a reduction of the FCC gasoline content.     

`Wagon-wheel¿ mask as a tool to study anisotropy of porous silicon formation rate

ABSTRACT: Relationship between the rate of electrochemical formation of mesoporous Si and the crystallographic directions has been studied by local anodization of wafers through a mask having the form of narrow long wedges radiating from the center in all directions ("wagon-wheel" mask). The etching rates were found from the side-etching under the thin transparent n-Si mask. On p+-substrates of various orientation diagrams characterizing the distribution of pore-formation rates over different directions in the wafer plane were constructed for the first time. The wagon-wheel method was applied to study the current dependence of the anisotropy. It was found that the orientation-related difference between the pore-formation rates is 5-25%, depending on the crystallographic direction and the etching current density. At a current density of ~ 9 mA/cm2 , the etching rates are related as V100 : V113 : V110 : V112 : V111 = 1.000 : 0.900 : 0.836 : 0.824 : 0.750. A general tendency is observed toward weakening of the anisotropy with increasing current. The highest rate always corresponds to the <100> direction, and the rate ratio between the other directions varies with increasing current, which leads to a change of their sequence.     

Temperature Measurement Deviation during Annealing of Multiphase Steels

A pyrometric analysis of the temperature of continuous annealed strip material is an essential component of industrial production. However, despite calibration, the development of composition-dependent oxides during annealing prevents an accurate pyrometric measurement of actual strip temperature. An Al-based and a Si-based transformation induced plasticity (TRIP)-assisted steel were pyrometrically analyzed during annealing under a reducing atmosphere (5 pct H₂ and 95 pct Ar). Oxide development on both steels led to a deviation between pyrometer readings and simultaneous thermocouple measurements. The developing oxides influenced the pyrometer readings to different extents because of unique emissivities and different growth kinetics.     

The Acute Effects of Leptin on the Contractility of Isolated Rat Atrial and Ventricular Cardiomyocytes

Leptin is a pleiotropic peptide playing an important role in the regulation of cardiac functions. It is not clear whether leptin directly modulates the mechanical function of atrial cardiomyocytes. We compared the acute effects of leptin on the characteristics of mechanically non-loaded sarcomere shortening and cytosolic Ca²⁺ concentration ([Ca²⁺]_i) transients in single rat atrial and ventricular cardiomyocytes. We also studied the functional properties of myosin obtained from cardiomyocytes using an in vitro motility assay and assessed the sarcomeric protein phosphorylation. Single cardiomyocytes were exposed to 5, 20, and 60 nM leptin for 60 min. In ventricular cardiomyocytes, 60 nM leptin depressed sarcomere shortening amplitude and decreased the rates of shortening and relaxation. These effects were accompanied by a decrease in the phosphorylation of cMyBP-C, an increase in Tpm phosphorylation, and a slowdown of the sliding velocity of thin filaments over myosin in the in vitro motility assay. In contrast, in atrial cardiomyocytes, the phosphorylation of cMyBP-C and TnI increased, and the characteristics of sarcomere shortening did not change. Leptin had no effect on the characteristics of [Ca²⁺]_i transients in ventricular cardiomyocytes, while 5 nM leptin prolonged [Ca²⁺]_i transients in atrial cardiomyocytes. Thus, leptin-induced changes in contractility of ventricular cardiomyocytes may be attributed to the direct effects of leptin on cross-bridge kinetics and sarcomeric protein properties rather than changes in [Ca²⁺]_i. We also suggest that the observed differences between atrial and ventricular cardiomyocytes may be associated with the peculiarities of the expression of leptin receptors, as well as signaling pathways in the atrial and ventricular myocardium.     

Plant_SNP_TATA_Z-Tester: A Web Service That Unequivocally Estimates the Impact of Proximal Promoter Mutations on Plant Gene Expression

Synthetic targeted optimization of plant promoters is becoming a part of progress in mainstream postgenomic agriculture along with hybridization of cultivated plants with wild congeners, as well as marker-assisted breeding. Therefore, here, for the first time, we compiled all the experimental data—on mutational effects in plant proximal promoters on gene expression—that we could find in PubMed. Some of these datasets cast doubt on both the existence and the uniqueness of the sought solution, which could unequivocally estimate effects of proximal promoter mutation on gene expression when plants are grown under various environmental conditions during their development. This means that the inverse problem under study is ill-posed. Furthermore, we found experimental data on in vitro interchangeability of plant and human TATA-binding proteins allowing the application of Tikhonov’s regularization, making this problem well-posed. Within these frameworks, we created our Web service Plant_SNP_TATA_Z-tester and then determined the limits of its applicability using those data that cast doubt on both the existence and the uniqueness of the sought solution. We confirmed that the effects (of proximal promoter mutations on gene expression) predicted by Plant_SNP_TATA_Z-tester correlate statistically significantly with all the experimental data under study. Lastly, we exemplified an application of Plant_SNP_TATA_Z-tester to agriculturally valuable mutations in plant promoters.