Ammonia recycling and cadmium confinement in chemical bath deposition of CdS thin layers

Cadmium sulfide thin layers in polycrystalline solar cells are produced by chemical bath deposition (CBD). This process produces wastes containing ammonia and cadmium. These two chemicals must be recovered, and if possible recycled, from an environmental and economic point of view. A process has been implemented in order to recover ammonia and to confine cadmium. A new closed reactor has been designed and fabricated in order to trap ammonia vaporized during the deposition step. Ammonia is absorbed from the exhaust gas from the CBD reactor. The wastes are treated in an ex situ process which enables recovery of the major part of the large amounts of ammonia used in the process. Concentrated solutions of pure ammonia are obtained (more than 10 mol/l). In connection with this operation, all of the cadmium, except a very small amount, is precipitated, mainly as cadmium sulfide, owing to decomposition of the thiourea introduced in excess. Microfiltration with a glass‐fiber filter of about 0.7 μm cut‐off produces a filtrate of very low cadmium concentration (< 10 μg/l). Optimization of both pH and residual ammonia concentration should make it possible to lower this residual cadmium concentration. This effluent is the only waste product of the process. The filtration cake containing cadmium compounds may be stored in specialized landfills after standard treatment or, better, treated to recover and recycle the metal without generation of any other harmful effluent. Copyright © 2001 John Wiley & Sons, Ltd.     

Protection of Cholinergic Neurons against Zinc Toxicity by Glial Cells in Thiamine-Deficient Media

Brain pathologies evoked by thiamine deficiency can be aggravated by mild zinc excess. Cholinergic neurons are the most susceptible to such cytotoxic signals. Sub-toxic zinc excess aggravates the injury of neuronal SN56 cholinergic cells under mild thiamine deficiency. The excessive cell loss is caused by Zn interference with acetyl-CoA metabolism. The aim of this work was to investigate whether and how astroglial C6 cells alleviated the neurotoxicity of Zn to cultured SN56 cells in thiamine-deficient media. Low Zn concentrations did not affect astroglial C6 and primary glial cell viability in thiamine-deficient conditions. Additionally, parameters of energy metabolism were not significantly changed. Amprolium (a competitive inhibitor of thiamine uptake) augmented thiamine pyrophosphate deficits in cells, while co-treatment with Zn enhanced the toxic effect on acetyl-CoA metabolism. SN56 cholinergic neuronal cells were more susceptible to these combined insults than C6 and primary glial cells, which affected pyruvate dehydrogenase activity and the acetyl-CoA level. A co-culture of SN56 neurons with astroglial cells in thiamine-deficient medium eliminated Zn-evoked neuronal loss. These data indicate that astroglial cells protect neurons against Zn and thiamine deficiency neurotoxicity by preserving the acetyl-CoA level.     

Cellular and Gene Expression Response to the Combination of Genistein and Kaempferol in the Treatment of Mucopolysaccharidosis Type I

Flavonoids are investigated as therapeutics for mucopolysaccharidosis, a metabolic disorder with impaired glycosaminoglycan degradation. Here we determined the effects of genistein and kaempferol, used alone or in combination, on cellular response and gene expression in a mucopolysaccharidosis type I model. We assessed the cell cycle, viability, proliferation, subcellular localization of the translocation factor EB (TFEB), number and distribution of lysosomes, and glycosaminoglycan synthesis after exposure to flavonoids. Global gene expression was analysed using DNA microarray and quantitative PCR. The type and degree of flavonoid interaction were determined based on the combination and dose reduction indexes. The combination of both flavonoids synergistically inhibits glycosaminoglycan synthesis, modulates TFEB localization, lysosomal number, and distribution. Genistein and kaempferol in a 1:1 ratio regulate the expression of 52% of glycosaminoglycan metabolism genes. Flavonoids show synergy, additivity, or slight antagonism in all analysed parameters, and the type of interaction depends on the concentration and component ratios. With the simultaneous use of genistein and kaempferol in a ratio of 4:1, even a 10-fold reduction in the concentration of kaempferol is possible. Flavonoid mixtures, used as the treatment of mucopolysaccharidosis, are effective in reducing glycosaminoglycan production and storage and show a slight cytotoxic effect compared to single-flavonoid usage.     

GPR18-Mediated Relaxation of Human Isolated Pulmonary Arteries

GPR18 receptor protein was detected in the heart and vasculature and appears to play a functional role in the cardiovascular system. We investigated the effects of the new GPR18 agonists PSB-MZ-1415 and PSB-MZ-1440 and the new GPR18 antagonist PSB-CB-27 on isolated human pulmonary arteries (hPAs) and compared their effects with the previously proposed, but unconfirmed, GPR18 ligands NAGly, Abn-CBD (agonists) and O-1918 (antagonist). GPR18 expression in hPAs was shown at the mRNA level. PSB-MZ-1415, PSB-MZ-1440, NAGly and Abn-CBD fully relaxed endothelium-intact hPAs precontracted with the thromboxane A₂ analog U46619. PSB-CB-27 shifted the concentration-response curves (CRCs) of PSB-MZ-1415, PSB-MZ-1440, NAGly and Abn-CBD to the right; O-1918 caused rightward shifts of the CRCs of PSB-MZ-1415 and NAGly. Endothelium removal diminished the potency and the maximum effect of PSB-MZ-1415. The potency of PSB-MZ-1415 or NAGly was reduced in male patients, smokers and patients with hypercholesterolemia. In conclusion, the novel GPR18 agonists, PSB-MZ-1415 and PSB-MZ-1440, relax hPAs and the effect is inhibited by the new GPR18 antagonist PSB-CB-27. GPR18, which appears to exhibit lower activity in hPAs from male, smoking or hypercholesterolemic patients, may become a new target for the treatment of pulmonary arterial hypertension.     

XPS study of titanium species exposed to molten Li2CO3-Na2CO3 in the anodic conditions used in molten carbonate fuel cells

The surface characterization of titanium, titanium oxide and lithium titanate samples exposed to molten Li₂CO₃-Na₂CO₃, in the anodic conditions used in molten carbonate fuel cells, was carried out by X-ray Photoelectron Spectroscopy (XPS). Different elements were identified: Ti(IV), O(-II), Li(I) and Na(I). The amounts of adsorbed sodium and lithium carbonates, as well as inserted lithium were estimated by a semi-quantitative XPS analysis in layers of about 50 Å. A broadening of the Ti 2p_3/2 peak was observed. This effect is probably caused by a distorsion of the Li₂TiO₃ lattice due to the incorporation of lithium within this structure. Li₂TiO₃ compound was detected by X-ray diffraction (XRD) on Ti, TiO₂ as well as Li₂TiO₃ after treatment in the molten carbonate eutectic.     

ATRP of (meth)acrylates initiated with a bifunctional initiator bearing trichloromethyl functional groups and structural analysis of the formed polymer

ATRP of methyl methacrylate (MMA), initiated with 1,3-bis{1-methyl-1-[(2,2,2-trichloroethoxy)carbonylamino]ethyl}benzene as a bifunctional initiator (BI) under CuCl catalysis was studied in the presence of 2,2′-bipyridine (bpy) or hexamethyltriethylenetetramine (HMTETA) ligands, in bulk or in toluene. With the bpy, the polymerization reaches only limited monomer conversions and products have broad MWDs. In contrast, polymerization in the presence of HMTETA is a well-controlled process, affords virtually quantitative conversion, giving PMMAs with narrow MWDs and predictable molecular weights within a range of more than one order of magnitude. NMR analysis of the prepared PMMA proved formation of linear polymers with im-measurable extent of chain branching or β-scission as undesired side reactions. The prepared α,ω-dichloro-PMMAs were used as macroinitiators for ATRP of tert-butyl acrylate (t-BuA), giving the corresponding triblock copolymers with narrow MWDs and molecular weights controllable in a wide range. Block copolymerizations were performed in dimethyl formamide (DMF) or acetone in the presence of pentamethyldiethylenetriamine (PMDETA) as ligand and could be accelerated by addition of metallic copper.     

Impact of goat milk powdered formulations on mineral absorption,peak bone mass and bone loss due to ovariectomy in rats

BACKGROUND: Goat milk is recognised as nutritious, with benefits to growth and skeletal development. The initial aim of this study was to investigate the effect of three different goat milk formulae—a whole milk, a skim milk and a goat milk growing‐up formula fortified with pre‐ and probiotics (Formula 1)—on mineral absorption and retention in rats. The effect of long‐term intake of the fortified formula diet on peak bone mass and post‐ovariectomy bone loss in rats was then investigated in a follow‐up study and was assessed by bone density dual‐energy X‐ray absorptiometry and biomechanical testing of bone ex vivo. RESULTS: Goat whole milk and fortified milk formulations improved calcium and phosphorus absorption and retention. Body composition analysis showed that rats fed the fortified diet had higher body calcium and phosphorus content. The fortified diet was then tested in a long‐term feeding trial. Rats fed the fortified diet from weaning had a higher peak bone mass than rats fed a soy protein control diet. Bone mineral content (BMC) and density (BMD) of the lumbar spine were higher in rats fed the fortified diet. After ovariectomy, all rats lost bone mass, but rats fed the fortified diet maintained significantly higher BMD and BMC values throughout the trial, though still lower than those of non‐ovariectomised control rats. The fortified diet increased bone strength. CONCLUSION: Goat milk specific nutrients supported by pre‐ and probiotics in Formula 1 may improve mineral status during growth and support attainment of peak bone mass. Copyright © 2008 Society of Chemical Industry