Solution of mass transfer in step growth polymerization in films with bulk in equilibrium

We have analyzed step growth polymerization in a flat film with finite mass transfer resistance. We have shown rigorously that the molecular weight distribution (MWD) at equilibrium is given by the Flory distribution, and under reaction the form of the MWD does not change if the feed is either pure monomer or in equilibrium initially. Extensive computations have shown that it is possible to split the film into growing interfacial and shrinking bulk regions. It is possible to obtain similarity transformations of concentrations of condensation product, and polymer as time invariant profiles. Based on this finding, we have determined a solution for step growth polymerization with finite mass transfer in films. The results lie within 5% of the “exact” numerical computations, for all possible variations of parameters.     

Effect of morphology on the performance of metal-hydride electrodes

Electrochemical studies on AB₂ type Zr_0.5Ti_0.5V_0.6Cr_0.2Ni_1.2 metal hydride electrodes with varying particle size suggests that the electrodes with alloy particles of about 60 m yield the optimum performance. The values for diffusion coefficient of hydrogen in the alloy particles > 25 m are found to be nearly invariant. Both a.c. impedance and linear polarization data on electrodes with varying particle size suggest that the charge-transfer resistance depends on state-of-charge of the electrodes. A comparison of scanning electron micrographs of fresh electrodes and subsequent to their prolonged charge-discharge cycling suggests that the metal hydride particles develop stress-induced cracks owing to their inherent expansion and contraction during the hydriding/dehydriding processes.     

Colloid Emulsion of Nanosized Strontium Bismuth Tantalate Powder

A novel colloid-emulsion process has been used to synthesize nanosized strontium bismuth tantalate (SrBi₂Ta₂O₉) particles. During calcination, the desired bismuth-layered structure phase develops at the expense of the pyrochlore phase. Calcining the precursor powder at 750°C for 2 h leads to the complete formation of single-phase layered-structured SrBi₂Ta₂O₉. The powder that is formed consists of nanoparticles with a narrow size distribution and almost-spherical morphology. The crystallinity of the calcined powder increases as the calcination temperature and heating time increases. The developed colloid-emulsion process significantly reduces the SrBi₂Ta₂O₉ particle size, in comparison to conventional process techniques, and results in a uniform microstructure of the obtained powder.     

Nutritional effects of mustard seed protein detoxified with aqueous isopropanol in young rats

The effect of removing anti‐nutritional factors from n‐hexane‐extracted mustard meal using 80% isopropanol (to reduce thioglucosides, phenolics, etc.) on growth, food efficiency ratio, serum and liver lipid profiles and protein content of young rats was examined. For this n‐hexane‐extracted mustard meal was extracted with 80% isopropanol giving a fraction with 68% protein and low residual thioglucoside (0.5%) as well as phenolic (0.3%) content. This isopropanol‐extracted mustard seed protein fraction reduced the growth of young rats slightly when compared with casein. The food efficiency ratio between rats fed isopropanol‐extracted mustard seed protein or casein did not differ, nor did the protein composition affect serum total cholesterol, triglyceride, HDL‐cholesterol, LDL‐cholesterol, VLDL‐cholesterol and LDL‐C/HDL‐C ratio. However, rats fed isopropanol‐extracted mustard seed protein showed a significantly lower (p<0.05) liver cholesterol concentration than rats fed casein. Liver triglyceride and phospholipid concentrations did not differ between rats fed the two proteins, nor was serum protein affected. This study indicates that extraction of hexane‐extracted mustard meal with 80% isopropanol reduced a number of anti‐nutritional factors like thioglucoside and phenolics. Furthermore the nutritional quality of mustard seed protein fraction is comparable to casein in respect to growth, food efficiency ratio, serum lipid and protein concentrations and organ weights.     

Electrodeposition of Nanocrystalline Nickel Coatings from a Deep Eutectic Solvent with Water Addition

Protection of Metals and Physical Chemistry of Surfaces - The electrodeposition of nanocrystalline Ni coatings from electroplating baths containing deep eutectic solvents (analogues of...     

Synergistic effect of some antiscalants as corrosion inhibitor for industrial cooling water system

In order to study synergistic effect, various combinations of antiscalants 1-hydroxyethane-1,1-diphosphonic acid (HEDP), sodium hexametaphosphate (SHMP), sodium tripolyphosphate (STPP), and trisodium phosphate (TSP), were investigated as corrosion inhibitors for carbon steel. Corrosion rate and percentage inhibition efficiency of various combinations of antiscalants as corrosion inhibitors (20/80, 40/60, 60/40, 50/50, 80/20, and 100 ppm of different combinations of HEDP, SHMP, STPP, and TSP) in synthetic cooling water VI (692 ppm of Cl⁻ ions) was determined by weight loss, electrochemical polarization technique, and metallurgical microscopy technique. It was observed that a 50/50 ppm combination of HEDP and SHMP gave 98% corrosion inhibition efficiency and maximum synergistic effect. The percentage inhibition efficiency of HEDP when mixed with other antiscalants as corrosion inhibitors at 50/50 ppm concentration was found in the following order HEDP/SHMP > HEDP/STPP > HEDP/TSP. The synergistic effect of HEDP/SHMP combination is due to intermolecular hydrogen bonding between the molecules of HEDP and SHMP, which results in the adsorption of uniform multilayered two-dimensional film of –HEDP–SHMP– molecules on carbon steel surface.     

Microcellular and nanocellular solid-state polyetherimide (PEI) foams using sub-critical carbon dioxide I. Processing and structure

In this study we investigate the solid-state batch foaming of polyetherimide (PEI) using sub-critical CO₂ as a blowing agent. We report on the gas diffusion for various saturation pressures in this system. Foaming process characterization is reported detailing conditions used to create microcellular and nanocellular PEI foams of 40% and higher relative density. Gas sorption, foaming, and resultant morphologies are analyzed and compared to previously reported results on PEI thin films. It was found that equilibrium gas concentrations for PEI sheet begin to significantly exceed that of films for CO₂ pressures above 3 MPa. A large solid-state foaming process window has been identified that allows for the creation of either microcellular or nanocellular structures at comparable density reductions. A transition from micro-scale cells to nano-scale cells was observed at gas concentrations in the range of 94–110 mg CO₂/g PEI. Additionally, a hierarchical structure was observed which consisted of nanocellular structures internal to microcells. The PEI–CO₂ system offers the unique opportunity to compare and contrast the bulk properties of nanofoams and microfoams.     

First X-ray structure of discrete anion [HgBr5]: Synthesis, characterization and single crystal X-ray structure determination of [Co(NH3)6][HgBr5]

A new cobalt(III) complex salt, [Co(NH₃)₆][HgBr₅](1) was crystallized from a solution of hexaamminecobalt(III)bromide and potassium tetrabromomercurate(II) in aqueous medium in 1:1 molar ratio. This complex salt has been characterized by elemental analyses, spectroscopic techniques (e.g. UV/Visible, IR), solubility product and conductance measurements. The complex salt crystallizes in Orthorhombic crystal system with space group Pnma. Single crystal X-ray structure determination revealed the presence of discrete ions: [Co(NH₃)₆]³⁺ cation and a new anion [HgBr₅]³⁻. This is the first structural report of a complex salt containing this new anion. The structure consists of stacks of cations and anions demonstrating supramolecular arrangements through N–HBr hydrogen-bond interactions. The crystal lattice is stabilized by these non-covalent interactions besides electrostatic interaction.     

Dicarbonylruthenium(II) complexes of diphosphine ligands and their catalytic activity

The hexa-coordinated chelate complexes of the type [Ru(CO)₂Cl₂(P-P)](1a,b) [where P-P = 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene(a) and [bis(2-diphenylphosphinophenyl)ether(b)] have been synthesized by reacting the polymeric precursor [Ru(CO)₂Cl₂]_n with the ligands in 1:1 molar ratio. The complexes 1a,b are characterized by elemental analyses, Mass, IR and NMR spectroscopy together with the single crystal X-ray structure determination of 1a. The compound 1a crystallizes in a monoclinic system with space group C2/c showing a slightly distorted octahedral geometry around the Ru centre. The complexes 1a and 1b are thermally stable up to 300 °C and exhibit high catalytic activity in transfer hydrogenation of aldehyde and ketones to corresponding alcohols. The complexes 1a and 1b show much higher catalytic activity for the hydrogenation of aldehyde than ketones. In general, the catalytic efficiency of 1b is higher compared with 1a.     

Essential Oil of <Emphasis Type="Italic">Artemisia scoparia</Emphasis> Inhibits Plant Growth by Generating Reactive Oxygen Species and Causing Oxidative Damage

We investigated the chemical composition and phytotoxicity of the essential oil extracted from leaves of Artemisia scoparia Waldst. et Kit. (red stem wormwood, Asteraceae). GC/GC-MS analyses revealed 33 chemical constituents representing 99.83% of the oil. The oil, in general, was rich in monoterpenes that constitute 71.6%, with β-myrcene (29.27%) as the major constituent followed by (+)-limonene (13.3%), (Z)-β-ocimene (13.37%), and γ-terpinene (9.51%). The oil and β-myrcene were evaluated in a dose–response bioassay under laboratory conditions for phytotoxicity against three weeds—Avena fatua, Cyperus rotundus, and Phalaris minor. A significant reduction in germination, seedling growth, and dry matter accumulation was observed in the test weeds. At the lowest treatment of 0.07 mg/ml Artemisia oil, germination was reduced by 39%, 19%, and 10.6% in C. rotundus, P. minor, and A. fatua, respectively. However, the inhibitory effect of β-myrcene was less. In general, a dose-dependent effect was observed and the growth declined with increasing concentration. Among the three weeds, the inhibitory effect was greatest on C. rotundus, so it was selected for further studies. We explored the explanation for observed growth inhibition in terms of reactive oxygen species (ROS: lipid peroxidation, membrane integrity, and amounts of conjugated dienes and hydrogen peroxide)-induced oxidative stress. Exposure of C. rotundus to Artemisia oil or β-myrcene enhanced solute leakage, indicating membrane disintegration. There were increased levels of malondialdehyde and hydrogen peroxide, indicating lipid peroxidation and induction of oxidative stress. We conclude that Artemisia oil inhibits plant root growth through generation of ROS-induced oxidative damage.