Field-induced phase transitions in chiral smectic liquid crystals studied by the constant current method

In ferroelectric liquid crystals, phase transitions can be induced by an electric field. The current constant method allows these transition to be quickly localized and thus the(E, T) phase diagram of the studied product can be obtained.In this work, we make a slight modification to the measurement principles based on this method. This modification allows the characteristic parameters of ferroelectric liquid crystal to be quantitatively measured. The use of a current square signal highlights a phenomenon of ferroelectric hysteresis with remnant polarization at null field, which points out an effect of memory in this compound.     

Determination of gasoline and diesel residues on wool,silk, polyester and cotton materials by SPME–GC–MS

The identification of ignitable liquids is very important and challenging aspect in arson crime investigations. The detection of gasoline and diesel fuel components using solid phase micro-extraction prior to gas chromatography–mass spectrometry for the forensic analysis of fire debris has been carried out. Previous works show that the absorption characteristics of the substrate are one of the most important factors in determining the evaporation rate of the accelerants. In order to determine the presence of the fuel residues, four of the most common substrate materials were tested in this work; wool, cotton, silk and polyester. The obtained results indicate that both gasoline and diesel fuel accelerants persisted longer on wool and silk than on the other selected substrates. Such information illustrates the influence of fuel persistence times after extinguishing and the best materials to be scanned for ignitable liquids at the fire scene.     

Oxide semiconductors for solar to chemical energy conversion: nanotechnology approach

The present work considers the application of oxide semiconductors in the conversion of solar energy into the chemical energy required for water purification (removal of microbial cells and toxic organic compounds from water) and the generation of solar hydrogen fuel by photoelectrochemical water splitting. The first part of this work considers the concept of solar energy conversion by oxide semiconductors and the key performance-related properties, including electronic structure, charge transport, flat band potential and surface properties, which are responsible to the reactivity and photoreactivity of oxides with water. The performance of oxide systems for solar energy conversion is briefly considered in terms of an electronic factor. The progress of research in the formation of systems with high performance is considered in terms of specific aspects of nanotechnology, leading to the formation of systems with high performance. The nanotechnology approach in the development of high-performance photocatalysts is considered in terms of the effect of surface energy associated with the formation of nanostructured system on the formation of surface structures that exhibit outstanding properties. The unresolved problems that should be tackled in better understanding of the effect of nanostructures on properties and performance of oxide semiconductors in solar energy conversion are discussed. This part is summarised by a list of unresolved problems of crucial importance in the formation of systems with enhanced performance. This work also formulates the questions that must be addressed in order to overcome the hurdles in the formation of oxide semiconductors with high performance in water purification and the generation of solar fuel. The research strategy in the development of oxide systems with high performance, including photocatalysts for solar water purification and photoelectrodes for photoelectrochemical water splitting, is considered. The considerations are focused on the systems based on titanium dioxide of different defect disorder as well as its solid solutions and composites.     

Identification of Molecular Transport Mechanisms in Micro-Porous Hydrotalcite–Silica Membrane

Hydrotalcite (HT) materials have been known to be able to adsorb \(\hbox {CO}_{2}\) even at high temperature. However, HT has not been made into a micro-porous membrane because of its meso-porous nature. In order to form a micro-porous HT membrane, silica was selected as a host matrix due to its ability to retain its micro-porosity. In this paper, a micro-porous hydrotalcite–silica membrane was formed on a meso-porous \(\upgamma \) -alumina layer supported by a macro-porous \(\upalpha \) -alumina substrate. Most of the micro-porosity determined from nitrogen adsorption measurement was found to be either closed or open but not interconnected, whereas most of the meso-porosity (at ca. 11.2 nm) in the micro-porous membrane was open and interconnected, thereby promoting gas flow. Viscous flow mechanism was observed to dominate transport of gases in macro-porous membrane. Knudsen diffusion dominated transport of gases in meso-porous membrane. On the other hand, surface affinity influenced the transport of carbon dioxide through the micro-porous membrane rather significantly. While permeability of pure hydrogen and carbon dioxide were independent of pressure, the permeability of the gases in the binary mixtures decreased with increasing pressure. Both experiment and simulation demonstrated consistent results.     

Phytochemical analysis, cytotoxic activity and constituents-activity relationships of the leaves of Cinnamomum iners (Reinw. ex Blume-Lauraceae)

The leaves of Cinnamomum iners (Reinw. ex Blume-Lauraceae) have been refluxed successively with chloroform and alcohol to get chloroform extract and alcoholic extract. Both the extracts have been assayed for cytotoxicity against human colorectal tumour cells. The chloroform extract exhibited significant cytotoxicity with IC(50) 31?μg mL(-1) (p??200?μg mL(-1). The chloroform extract has been further proceeded for chemical analysis by GC-TOFMS and 178 components were identified including acids, amines, amides, aldehydes, alcohols, esters, benzene derivatives, bicyclic compounds, terpenes, hydrocarbons, naphthalene derivatives, furan derivatives, azulenes, etc. Nine components representing 51.73% of the total chloroform extract were detected as major components. Caryophyllene (14.41%) and Eicosanoic acid ethyl ester (12.17%) are the most prominent components of the chloroform extract. β-Caryophyllene (14.41%) as most abundant compound supports potent cytotoxicity as shown by chloroform extract.     

Improvement of Ethanol Yield from Glycerol via Conversion of Pyruvate to Ethanol in Metabolically Engineered <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

The conversion of low-priced glycerol to higher value products has been proposed as a way to improve the economic viability of the biofuels industry. In a previous study, the conversion of glycerol to ethanol in a metabolically engineered strain of Saccharomyces cerevisiae was accomplished by minimizing the synthesis of glycerol, the main by-product in ethanol fermentation processing. To further improve ethanol production, overexpression of the native genes involved in conversion of pyruvate to ethanol in S. cerevisiae was successfully accomplished. The overexpression of an alcohol dehydrogenase (adh1) and a pyruvate decarboxylase (pdc1) caused an increase in growth rate and glycerol consumption under fermentative conditions, which led to a slight increase of the final ethanol yield. The overall expression of the adh1 and pdc1 genes in the modified strains, combined with the lack of the fps1 and gpd2 genes, resulted in a 1.4-fold increase (about 5.4 g/L ethanol produced) in fps1Δgpd2Δ (pGcyaDak, pGupCas) (about 4.0 g/L ethanol produced). In summary, it is possible to improve the ethanol yield by overexpression of the genes involved in the conversion of pyruvate to ethanol in engineered S. cerevisiae using glycerol as substrate.     

Thermal properties of polyimide system containing silicone segments

The influence of the structure properties relationships of silicone incorporated polyimide (PI) on thermal stability was investigated by using single scan thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) in nitrogen. Four systems have been synthesized based on monomer 4-(4-(1-(4-(4-aminophenoxy) phenyl)-1-methylethyl) phenoxy) aniline (BAPP)/3,3??,4,4??-Biphenyltetracarboxylic dianhydride including parent PI (S-1), PI siloxane copolymer (S-2 and S-3), and PI siloxane hybrid (S-4). The derivative thermogravimetric analysis (DTG) and DSC curves indicate a double and single stage decomposition process and glass transition temperature (T _g), respectively. While the PI, PIS, and PSH showed distinctive features towards thermal analysis, it was found that the rate of degradation (???/??t) was influenced by the flexibility of Si?CO?CSi in the backbone and in Si?CO?CSi itself. These results revealed that the presence of Si?CO?CSi in either the backbone or matrix indicates its stability with regard to high thermal service applications.     

Identification and Separation of Lead (II), Nickel (II), and Cobalt (II) on Silica Gel 60 F254 High-Performance Thin-Layer Chromatographic Plates with Mixed Aqueous Sodium Dodecyl Sulfate—Oxalic Acid Solvent System

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic separation of three metal cations was performed on high-performance thin-layer plates (silica gel 60F254) with...     

Trigonal–planar silver coordination in (3,5‐di­nitro­benzoato)­bis­(tri­phenyl­phosphine)­silver(I)

The three‐coordinate Ag atom in the title compound, [Ag(C₇H₃N₂O₆)(C₁₈H₁₅P)₂], shows trigonal–planar coordination [P—Ag—P = 147.1 (1)° and Σ_Ag = 359.0 (3)°]. Adjacent mol­ecules are linked through the O atoms of adjacent nitro groups [Ag?O = 3.205 (3) and 3.302 (4) Å] into a zigzag chain running parallel to the c axis.     

The Intestinal and Biliary Metabolites of Ibuprofen in the Rat with Experimental Hyperglycemia

Hyperglycemia is reported to be associated with oxidative stress. It can result in changes in the activities of drug-metabolizing enzymes and membrane-integrated transporters, which can modify the fate of drugs and other xenobiotics; furthermore, it can result in the formation of non-enzyme catalyzed oxidative metabolites. The present work aimed to investigate how experimental hyperglycemia affects the intestinal and biliary appearance of the oxidative and Phase II metabolites of ibuprofen in rats. In vivo studies were performed by luminal perfusion of 250 μM racemic ibuprofen solution in control and streptozotocin-treated (hyperglycemic) rats. Analysis of the collected intestinal perfusate and bile samples was performed by HPLC-UV and HPLC-MS. No oxidative metabolites could be detected in the perfusate samples. The biliary appearance of ibuprofen, 2-hydroxyibuprofen, ibuprofen glucuronide, hydroxylated ibuprofen glucuronide, and ibuprofen taurate was depressed in the hyperglycemic animals. However, no specific non-enzymatic (hydroxyl radical initiated) hydroxylation product could be detected. Instead, the depression of biliary excretion of ibuprofen and ibuprofen metabolites turned out to be the indicative marker of hyperglycemia. The observed changes impact the pharmacokinetics of drugs administered in hyperglycemic individuals.