ALBERT

Notes: Abstract CuInSe2 thin films have been prepared by high Se vapor selenization of co-sputtered Cu–In alloy precursors within a partially closed graphite container. Cu–In alloys with different compositions were investigated. X-ray diffraction (XRD) analysis of the films showed mainly CuIn2 and Cu11In9 phases and the Cu11In9 peak intensity was found to increase as the alloy composition tended towards Cu-rich. A linear dependence of the alloy composition on the Cu/In deposition power was observed from energy dispersive analysis by X-rays (EDX). A three-fold volume expansion was exhibited by all the CuInSe2 films after selenization at 500–550 °C. Scanning electron microscopy (SEM) analysis of the films showed large and densely packed crystal structures with sizes above 5 μm. The CuInSe2 films exhibited single phase chalcopyrite structure with preferential orientation in the (1 1 2) direction. The EDX composition analyses of the films showed Cu/In ratio ranging from 0.43 to 1.2, and Se/(Cu+In) ratios from 0.92 to 1.47. The measured film resistivities varied from 10-1 to 105 Ωcm. The Cu–In alloy precursors with Cu/In ratio less than 0.70 were found to form CuIn3Se5 a defect chalcopyrite compound. All films were Se rich, with the exception of samples with very high Cu content.© 1998 Kluwer Academic Publishers

Notes: Abstract Semi-interpenetrating polymer network (semi-IPN) hydrogels composed of β-chitosan and poly(ethylene glycol) diacrylate macromer (PEGM) were synthesized and characterized for the application as potential biomedical materials. The mixture of PEGM and β-chitosan, dissolved in water including a small amount of acetic acid, was cast to prepare hydrogel films, followed by a subsequent crosslinking with 2,2-dimethoxy-2-phenylacetophenone as a non-toxic photoinitiator by ultraviolet irradiation. Photocrosslinked hydrogels exhibited relatively high equilibrium water content in the range 77–83% which is mainly attributed to the free water content rather than to the bound water, hydrogen bonded with components in semi-IPN hydrogels. The crystallinity, thermal properties and mechanical properties of semi-IPN hydrogels were studied. All the photocrosslinked hydrogels revealed a remarkable decrease in crystallinity. The glass transition temperatures, Tg, of crosslinked PEGM segment in semi-IPNs increased compared with poly(ethylene glycol) itself. However, with increasing β-chitosan content their Tg decreased owing to the higher degree of crosslinking. The tensile strengths of semi-IPNs in dry state were rather high, but those of hydrogels in wet state decreased drastically.

Notes: Abstract One of the critical issues in the effective use of surrogate relaxation for an integer programming problem is how to solve the surrogate dual within a reasonable amount of computational time. In this paper, we present an exact and efficient algorithm for solving the surrogate dual of an integer programming problem. Our algorithm follows the approach which Sarin et al. (Ref. 8) introduced in their surrogate dual multiplier search algorithms. The algorithms of Sarin et al. adopt an ad-hoc stopping rule in solving subproblems and cannot guarantee the optimality of the solutions obtained. Our work shows that this heuristic nature can actually be eliminated. Convergence proof for our algorithm is provided. Computational results show the practical applicability of our algorithm.

Notes: Abstract The Escherichia colirnpA gene encodes C5 protein, the protein component of RNase P. The rnpA49 mutation renders the C5 protein thermosensitive, which results in thermosensitivity of RNase P function. The chromosomal DNA region from Brevibacterium albidum that complements the rnpA49 mutation was analysed. The gene capable of complementing the growth defect of an rnpA49 mutant strain at nonpermissive temperature was identified as the gene for an arginine tRNA with anticodon CCG by a deletion analysis combined with complementation assays. Transcription of the arginine tRNA gene carried on a multicopy plasmid was correlated with the complementation of the rnpA49 mutation, indicating that the gene product is indeed responsible for complementation of the rnpA49 mutation.

Notes: Abstract The Janggun iron deposits, Republic of␣Korea, occur as lens-shaped magnesian skarn, magnetite and base-metal sulfide orebodies developed in the Cambrian Janggun Limestone Formation. Mineralization stage of the deposits can be divided into two separate events. The skarn stage (107 Ma) consists of magnetite, pyrrhotite, base-metal sulfides, carbonates and magnesian skarn minerals. The hydrothermal stage (70 Ma) consists of base-metal sulfides, native bismuth, bismuthinite, tetrahedrite, boulangerite, bournonite and stannite. Mineral assemblages, chemical compositions and thermodynamic considerations indicate that formation temperatures, −log fs2 and −log fo2 values of ore fluids from the skarn stage were 433 to 345 °C, 8.1 to 9.7 bar and 29.4 to 31.6 bar, and the hydrothermal stage was 245 to 315 °C, 10.4 to 13.2 bar and 33.6 to 35.4 bar, respectively. Thermochemical considerations indicate that the XCO2 during magnesian skarnization ranged from 0.06 to 0.09, and the activity of H+ presumably decreased when the fluids equilibrated with host dolomitic limestone which resulted in a pH change from about 6.1 to 7.8, and decreases in fo2 and fs2. The δ34S values of ore sulfides have a wide range from 3.2 to 11.6 ‰ (CDT). Calculated 34SH2 S values of ore fluids are 2.9 to 5.4 ‰ (skarn stage) and 8.7 to 13.5 ‰ (hydrothermal stage). These are interpreted to represent an initial deep-seated, igneous source of sulfur which gave way to influence of oxidized sedimentary sulfur to hydrothermal stage. The δ13C values of carbonates in ores range from −4.6 to −2.5 ‰ (PDB). It is likely that carbon in the ore fluids was a mixture of deep-seated magmatic carbon and dissolved carbon of dolomitic limestone. The δ18OH2 O and δD values (SMOW) of water in the ore fluids were 14.7 to 1.8 and −85 to −73 ‰ during the skarn stage and 11.1 to −0.2 and −87 to −80 ‰ in the hydrothermal stage.

Notes: Abstract Analyses of stable isotope (δ13C and δ15N) and C:N ratios of food webs within a floodplain and a constricted-channel region of the Ohio River during October 1993 and July 1994 indicate that the increasingly influential flood pulse concept (FPC) does not, for either location, adequately address food web structure for this very large river. Furthermore, results of this study suggest that the riverine productivity model (RPM) is more appropriate than the widely known river continuum concept (RCC) for the constricted region of this river. These␣conclusions are based on stable isotope analyses of potential sources of organic matter (riparian C3 trees, riparian C4 grasses and agricultural crops, submerged macrophytes, benthic filamentous algae, benthic particulate organic matter, and transported organic matter containing detritus and phytoplankton) and various functional feeding groups of invertebrate and fish consumers. The FPC, which stresses the key contribution of organic matter, particularly terrestrial organic matter, originating from the floodplain to riverine food webs, was judged inappropriate for the floodplain region of the Ohio River for hydrodynamic and biotic reasons. The rising limb and peak period of discharge typically occur in November through March when temperatures are low (generally much less than 10°C) and greater than bank-full conditions are relatively unpredictable and short-lived. The major food potentially available to riverine organisms migrating into the floodplain would be decaying vegetation because autotrophic production is temperature and light limited and terrestrial insect production is minimal at that time. It is clear from our data that terrestrial C4 plants contribute little, if anything, to the consumer food web (based on δ13C values), and δ15N values for C3 plants, coarse benthic organic matter, and fine benthic organic matter were too depleted (∼7–12‰ lower than most invertebrate consumer values) for this organic matter to be supporting the food web. The RPM, which emphasizes the primary role of autotrophic production in large rivers, is the most viable of the remaining two ecosystem models for the constricted-channel region of the Ohio based on stable isotope linkage between sources and consumers of organic matter in the food web. The most important form of food web organic matter is apparently transported (suspended) fine (FTOM) and ultra-fine particulate organic matter. We propose that phytoplankton and detritus of an autochthonous origin in the seston would represent a more usable energy source for benthic (bivalve molluscs, hydropsychid caddisflies) and planktonic (microcrustaceans) suspension feeders than the more refractory allochthonous materials derived from upstream processing of terrestrial organic matter. Benthic grazers depend heavily on nonfilamentous benthic algae (based on gut analysis from a separate study), but filamentous benthic algae have no apparent connection to invertebrate consumers (based on δ13C values). Amphipod and crayfish show a strong relationship to aquatic macrophytes (possibly through detrital organic matter rather than living plant tissue). These observations contrast with the prediction of the RCC that food webs in large rivers are based principally on refractory FTOM and dissolved organic matter from upstream inefficiencies in organic-matter processing and the bacteria growing upon these suspended or dissolved detrital compounds. The conclusions drawn here for the Ohio River cannot yet be extended to other floodplain and constricted-channel rivers in temperate and tropical latitudes until more comparable data are available on relatively pristine and moderately regulated rivers.

Notes: Abstract Dispersal is essential in order that endemic species living in ephemeral, patchy vent environments may persist over evolutionary time. Quantitative field studies of larval dispersal, however, require specieslevel identification of the larval forms because each individual must be distinguished from related vent species, and from non-vent species living in the surrounding deep-sea environment. Methods for culturing these larvae to an identifiable stage have not yet been developed. To solve the larval identification problem for the archaeogastropod molluscs (a prominent component of vent communities), we used a scanning electron microscope (SEM) to image shells of larvae collected in the water column near vents along the East Pacific Rise (9°40′ to 9°50′N; 104°W). Larval shell size, shape and ornamentation were compared to protoconchs retained in juvenile or adult shells of identified species, and used to assign five larval groups unequivocally to species (Cyathermia naticoides Warén and Bouchet, 1989; Neomphalus fretterae McLean, 1981; Clypeosectus delectus McLean, 1989; Rhynchopelta concentrica McLean, 1989; and Lirapex granularis Warén and Bouchet, 1989) and seven groups tentatively to species or genus [Lepetodrilus spp. (three groups); Gorgoleptis sp; Peltospira ?operculata McLean, 1989; and ?Melanodrymia sp. (two groups)].

Notes: Summary The rate of hydrolysis of protein-methyl ester, the enzymatic product of S-adenosylmethionine: proteincarboxyl methyltransferase (EC.2.1.1.24) acting on oxidized ribonuclease, was measured at pH 7.1 and 8.6 at 37°C. The half-life of the hydrolysis of the ester is 25 min at pH 7.1, and 4 min at 8.6. The rate of hydrolysis of the enzymatically formed esters at pH 7.0, in 0.1M phosphate buffer, was about 25 times faster than that of esters formed chemically by reaction with methanol in HCl. The lability of the enzymatically synthesized protein-methyl ester suggests that the esterification is specific to sites such that ionization of neighboring amino acid side chains enhances the rate of the hydrolysis.

Notes: Abstract. A mistletoe lectin was isolated from water extracts of Korean mistletoe, a subspecies of Viscum album, grown on Quercus mongolica using CM-Sepharose chromatography followed by an affinity chromatography on a concanavalin A-Sepharose column. The compound proved to be a mistletoe lectin II with D-galactose and N-acetyl-D-galactosamine specificity. Matrix-assisted laser desorption time-of-flight mass spectroscopy showed it to have an average molecular mass of 62.7 kDa and to consist of two subunits of 30.6 kDa and 32.5 kDa. It was a basic protein with isoelectric points of 9.4 and 9.6 by capillary isoelectric focusing and was cytotoxic to Molt4 cell.