Copper complexing properties of melanoidins and marine humic material

Melanoidins, condensation products of sugars and amino acids, represent a key link in the transformation of polysaccharides to humic material in the marine environment. We investigated the complexing capacity of melanoidins that were prepared in deionized water and seawater and separated into different molecular mass fractions. The copper complexing properties of humic material isolated from marine lagoon sediments were determined for comparison. Melanoidins prepared using condensation times longer than two days exibit complexation properties towards copper ions that appear to depend on the basicity of the amino acid precursor and the molecular mass of the product. Pseudomelanoidins, prepared from glucose only, do not complex copper ions at all, regardless of the molecular mass. The highest copper complexing capacity value among melanoidins was measured for a glucose-lysine melanoidin with molecular mass fraction >10 kD (L(T)=2.1x10(-7) molCu(2+)/L). Melanoidin prepared from glucose and glutamic acid >10 kD was similar in complexing capacity to fulvic acid (1-20 kD molecular mass) isolated from lagoon sediments. The presence of calcium and magnesium ions and other macro and microconstituents in the seawater used to prepare melanoidins influences its complexing properties towards metal ions.     

Dynamic reconfiguration schemes for megabit BiCMOS SRAMs and performance evaluation

In this paper two dynamic configuration schemes are discussed for megabit BiCMOS static random access memories (SRAMs). Dynamic reconfiguration schemes allows failure detection at the chip level and automatic reconfiguration to fault free memory cells within the chip. The first scheme is a standby system approach where the I/O lines of the memory can be dynamically switched to spare bit slices in the SRAM. This scheme is implemented through a switching network at the memory interface. Every memory access is controlled by a fault status table (FST) which memorizes the fault conditions of each memory block. This FST is implemented outside the memory system. A second dynamic reconfiguration scheme for BiCMOS SRAMs is addressed through a graceful degradation approach. Basic design considerations and performance evaluation of megabit BiCMOS SRAMs using dynamic reconfiguration schemes are presented. The basic properties of the proposed schemes and a prototype VLSI chip implementation details are discussed. BiCMOS SRAM access time improvement of about 35%, chip area of 25%, and chip yield of 10% are achieved, respectively, as compared to conventional methods. A comparison of reliability improvement of 1 Mb BiCMOS SRAMs using dynamic configuration schemes is presented. These two dynamic reconfiguration schemes have considerable importance in reliability improvement when compared to conventional methods. The major advantage is that the size of reconfiguration of the system can be considerably reduced.     

Pattern of volatile compounds in dominant and subordinate male mouse urine

The urinary volatiles from dominant and subordinate male mice were chromatographically compared, both immediately and seven days after dominant-subordinate relationships between pairs were formed. Statistical comparison of the peak areas of volatile constituents present in male urine revealed that 16 urinary compounds exhibited substantial concentration differences depending upon social status of the animals. Urinary dihydrofurans, ketones, and acetates exhibited a significant, long-term (seven-day) decrease in the urine of subordinates when compared to control and dominant males. Two sesquiterpenic compounds, - and -farnesene, were elevated only in the dominant urine one week after dominance was established. 2-(sec-Butyl)-4,5-dihydrothiazole was found in higher concentration in bladder or excreted urine of dominant males when compared to subordinates. Of the 16 compounds subjected to statistical analysis, four exhibited hormonal dependency: - and -farnesene, dehydro-exo-brevicomin, and 2-(sec-butyl)-4,5-dihydrothiazole. Neither dehydro-exo-brevicomin nor 2-(sec-butyl)-4,5-dihydrothiazole was present in the urine of immature and castrated males. Testosterone treatment restores their presence in male urine. Also, - and -farnesene were absent in the urine of immature males and significantly reduced in the urine of castrated males. The absence of - and -farnesene in bladder urine suggests that one of the sex-accessory glands may be the site of their origin.     

Hyper-crosslinked sorbents for hemoperfusion

Pore structure changes of swelling sorbents, which were obtained from styrene and divinylbenzene (DVB) by additional crosslinking with α,α′-dichloro-p-xylene in the presence of tin chloride catalyst and in dichloroethane solution, were examined. It was found that the amount of dichloroxylene influences the swelling decrease and the increase of sorption ability of sorbents for chemical compounds with low molecular weight. Hemocompatibility was imparted to the sorbent and it was useful for hemoperfusion when a small amount of sulfonyl groups (about 0.2 mmol/g) had been introduced.     

Transdermal and buccal delivery of methylxanthines through human tissue in vitro

We examined the in vitro permeation of central nervous stimulants—caffeine, theophylline, and theobromine across human skin with the aid of six chemical enhancers. It was found that oleic acid was the most potent enhancer for all three methylxanthines. Further optimization studies with different solvents showed that caffeine transport could be enhanced to give flux values up to 585 μg/cm².hr^-1. Theobromine and theophylline delivery rates proved insufficient. An additional study involving a buccal tissue equivalent showed that this membrane was more permeable than skin for all model actives tested and would offer an alternate way of delivery.     

Changes in the Cell Wall Proteome of Leaves in Response to High Temperature Stress in Brachypodium distachyon

High temperature stress leads to complex changes to plant functionality, which affects, i.a., the cell wall structure and the cell wall protein composition. In this study, the qualitative and quantitative changes in the cell wall proteome of Brachypodium distachyon leaves in response to high (40 °C) temperature stress were characterised. Using a proteomic analysis, 1533 non-redundant proteins were identified from which 338 cell wall proteins were distinguished. At a high temperature, we identified 46 differentially abundant proteins, and of these, 4 were over-accumulated and 42 were under-accumulated. The most significant changes were observed in the proteins acting on the cell wall polysaccharides, specifically, 2 over- and 12 under-accumulated proteins. Based on the qualitative analysis, one cell wall protein was identified that was uniquely present at 40 °C but was absent in the control and 24 proteins that were present in the control but were absent at 40 °C. Overall, the changes in the cell wall proteome at 40 °C suggest a lower protease activity, lignification and an expansion of the cell wall. These results offer a new insight into the changes in the cell wall proteome in response to high temperature.     

Phase formations during mechanochemical synthesis of PbTiO<Subscript>3</Subscript>

Lead titanate nanopowders were fabricated by mechanochemical synthesis from lead oxide and titanium dioxide. The milling process has been carefully investigated by X-ray diffraction and X-ray excited photoelectron spectroscopy. The first traces of perovskite phase were detected after 5 h synthesis. It was found that intermediated phases (Ti₁₀O₁₈ and Pb₃O₄) have been formed at the early stage of synthesis. The 50 h milling results in single perovskite phase with average crystallite size of 20 nm.     

The effect of titanium ion implantation into carbon ceramic on its wettability by liquid copper

There is a growing interest in the carbon ceramics and their use in present technology. Among other problems, the joining of such ceramics with other materials presents an important challenge. Since joining with metals is associated with wetting, we studied the effect of ion implantation on wetting of various forms of carbon and of silicon carbide by copper. An essential result is that Ti ion implantation followed by ArcPVD Ti deposition results in excellent wettability in all studied cases.