Copper(I) 2-pyridyl selenolates and tellurolates: synthesis, structures and their utility as molecular precursors for the preparation of copper chalcogenide nanocrystals and thin films

The complexes, [Cu{EC(5)H(3)(R-3)N}](4) (E/R = Se/Me or Te/R; R = H or Me) were isolated by the reaction between CuCl and NaEC(5)H(3)(R-3)N and were characterized by elemental analyses, uv-vis and NMR ((1)H, (13)C) spectroscopy. The crystal structures of [Cu{SeC(5)H(3)(Me-3)N}](4) and [Cu(TeC(5)H(4)N)](4) revealed that the molecules are tetrameric in which each copper atom lies at the vertex of the tetrahedron and each face of the tetrahedron is capped by the bridging pyridylchalcogenolate ligand. Thermal behavior of these complexes was studied by thermogravimetric analysis. Depending on reaction conditions, thermolysis gave both stoichiometric and non-stoichiometric copper chalcogenides, which were characterized by XRD, EDX, SEM, TEM and SAED techniques. These precursors were used for the preparation of nanocrystals and for deposition of thin films of copper chalcogenides by AACVD (Aerosol Assisted Chemical Vapor Deposition).     

Systematic study of multiparticle production in nucleus–nucleus interactions at 14.6 A GeV

An experimental analysis of 855 events induced by 14.6 A GeV ²⁸Si in nuclear emulsion is presented. Mean multiplicities of charged secondary particles produced in the nuclear interactions are studied and compared with the results from the other experiments for the same projectile at 3.7 A GeV as well as data for proton at similar energy (14 GeV). An analysis of pseudorapidity densities of target fragments (black and grey particles) is also performed. The behaviour of the KNO scaling law of the multiplicity distribution for shower particles has been examined. In order to accumulate knowledge about the intermittent behaviour of shower particles, the scaled factorial moments (SFMs) are computed in η-space and ?-space for a set of data in the ²⁸Si–AgBr events. Furthermore, validity of limiting fragmentation of shower particles produced in central collision events induced by ²⁸Si-emulsion interactions has been tested. A crude estimation for the energy density of the nuclear matter formed in the central collision events at our energy has been examined.     

Banana fiber-reinforced biodegradable soy protein composites

Banana fiber, a waste product of banana cultivation, has been used to prepare banana fiber reinforced soy protein composites. Alkali modified banana fibers were characterized in terms of density, denier and crystallinity index. Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were also performed on the fibers. Soy protein composites were prepared by incorporating different volume fractions of alkali-treated and untreated fibers into soy protein isolate (SPI) with different amounts of glycerol (25%–50%) as plasticizer. Composites thus prepared were characterized in terms of mechanical properties, SEM and water resistance. The results indicate that at 0.3 volume fraction, tensile strength and modulus of alkali treated fiber reinforced soy protein composites increased to 82% and 963%, respectively, compared to soy protein film without fibers. Water resistance of the composites increased significantly with the addition of glutaraldehyde which acts as cross-linking agent. Biodegradability of the composites has also been tested in the contaminated environment and the composites were found to be 100% biodegradable.     

Unique Use of Alkylation for Chemo‐Redox Activity by a PtIV Prodrug

Resistance towards chemotherapeutics displayed by cancer cells is a significant stumbling block against fruitful cisplatin‐based therapy. A unique dual‐acting chemotherapeutic modality, Platin‐B, a prodrug of cisplatin and pipobroman‐mimicking alkylating agent, was constructed to circumvent tumor resistance. Platin‐B exhibited a superior cytotoxicity profile in cisplatin‐resistant cancer cells. Enhanced activity and the ability to overcome cancer‐induced resistance of Platin‐B was related to adduct formation with intracellular glutathione, followed by the activity of Platin‐B on the mitochondria of cells, along with its conventional nuclear activity. Alkylating moieties present on Platin‐B enhanced its cellular and subcellular concentration and protected it from early drug sequestration by biological thiols.     

Gas holdup in three-phase immobilized-cell bioreactors

A number of studies in the published literature deal with gas holdup in three-phase reactors. However, very few address the cases in which the solid density approaches that of the liquid phases and in which low gas velocities are involved. These conditions are commonly encountered in immobilized-cell bubble columns and in fluidized-bed bioreactors. This paper reports the effect of gas and liquid velocity upon gas holdup and bed expansion in fluidized-bed bioreactors. For liquid-fluidization of low-density alginate beads in the absence of gas, the terminal sedimentation velocity (vT) of the particles is a constant, and expansion of the bed follows Richardson and Zaki’s correlation. In the presence of gas, however, the apparent terminal sedimentation velocity value is affected by the velocity of the gas and liquid phases. For gas velocities above a minimum value, the calculated value of vT depends on liquid velocity only, and a constant bed expansion was observed for a range of gas and liquid flow rates. For the gas-liquid interactions, a modified drift-flux model was found to be valid. For superficial gas velocities between 5 and 17 cm/min, the modified drift-flux velocity was observed to be a function of gas velocity, suggesting the prevalence of a coalescence regime.     

Extendability and von Neuman–Morgenstern stability of the core

This paper introduces a strengthening of the notion of a stable core and characterizes it in terms of Kikuta and Shapley’s extendability condition.     

Redox potential in acetone-butanol fermentations

In batch and continuous cultivations ofClostridium acetobutylicum ATCC 824 on lactose, a strong relationship was observed between redox potential of broth and the cellular metabolism. The specific productivity of butanol as well as of butyric acid was found to be maximum at a redox potential of -250 mV. The specific production rate of butyric acid decreased rapidly at redox potentials. For butanol, however, it achieved a lower but stable value. This was true for dynamic as well as steady states. The continuous fermentations involving lactose exhibited sustained oscillations at low dilution rates. These oscillations appear to be related to butanol toxicity to the growth of cells. At higher dilution rates where butanol concentrations were relatively low, no such oscillations were observed. It can be concluded that broth redox potential is an excellent indicator of the resulting fermentation product partitioning.