Geochemistry and mineralogy of platinum-group elements (PGE) in chromites from Centralnoye I, Polar Urals, Russia

The Polar Urals region of northern Russia is well known for large chromium(Cr)-bearing massifs with major chromite orebodies,including the Centralnoye I deposit in the Ray-lz ultramafic massif of the Ural ophiolite belt.New data on platinum(Pt)-group elements(PGE),geochemistry and mineralogy of the host dunite shows that the deposit has anomalous iridium(It)values.These values indicate the predom-inance of ruthenium-osmium-iridium(Ru-Os-lr)-bearing phases among the platinum-group mineral(PGM)assemblage that is typical of mantle-hosted chromite ores.Low Pt values in chromites and increased Pt values in host dunites might reflect the presence of cumulus PGM grains.The most abundant PGM tbund in the chromite is erlichmanite(up to 15 μm).Less common are cuproiridsite(up to 5 μm),irarsite(up to4-5 μm),and laurite(up to 4 μm).The predominant sulfide is heazlewoodite,in intergrowth with Ni--Fe alloys,sporadically with pentlandite,and rarely with pure nickel.Based on the average PGE values and esti-mated Cr-ore resources,the Centralnoye I deposit can be considered as an important resource of PGE.     

Improvement of Mechanical Properties of Automotive Components Using Hot Stamping With Integrated Q-P Process

Cold forming of high strength materials is accompanied by an undesirable spring-back effect and therefore the automotive industry prefers to produce components from high strength steels by hot stamping.Hot deformation and cooling in a die are applied to obtain shaped components with martensitic microstructure and high yield strength and ultimate tensile strength.This article presents new applications of this forming technology by incorporating another innovative heat treatment by the Q-P process,which improves both strength and ductility of obtained structures at the same time.Ultimate strengths over 2000 MPa with ductility above 10% can be achieved by this processing.To test microstructure development,thin sheet was hot formed and a corresponding FEM simulation was created.This processing was applied to low alloyed AHS steel with 0.42% of carbon and with an alloying strategy based on Mn,Si and Cr.Martensitic microstructure with retained austenite was obtained by this processing with a strength of around 2000 MPa and ductility of 10%.     

Plant_SNP_TATA_Z-Tester: A Web Service That Unequivocally Estimates the Impact of Proximal Promoter Mutations on Plant Gene Expression

Synthetic targeted optimization of plant promoters is becoming a part of progress in mainstream postgenomic agriculture along with hybridization of cultivated plants with wild congeners, as well as marker-assisted breeding. Therefore, here, for the first time, we compiled all the experimental data—on mutational effects in plant proximal promoters on gene expression—that we could find in PubMed. Some of these datasets cast doubt on both the existence and the uniqueness of the sought solution, which could unequivocally estimate effects of proximal promoter mutation on gene expression when plants are grown under various environmental conditions during their development. This means that the inverse problem under study is ill-posed. Furthermore, we found experimental data on in vitro interchangeability of plant and human TATA-binding proteins allowing the application of Tikhonov’s regularization, making this problem well-posed. Within these frameworks, we created our Web service Plant_SNP_TATA_Z-tester and then determined the limits of its applicability using those data that cast doubt on both the existence and the uniqueness of the sought solution. We confirmed that the effects (of proximal promoter mutations on gene expression) predicted by Plant_SNP_TATA_Z-tester correlate statistically significantly with all the experimental data under study. Lastly, we exemplified an application of Plant_SNP_TATA_Z-tester to agriculturally valuable mutations in plant promoters.     

The Effects of Sperm and Seminal Fluid of Immunized Male Mice on In Vitro Fertilization and Surrogate Mother–Embryo Interaction

The latest vaccination campaign has actualized the potential impact of antigenic stimuli on reproductive functions. To address this, we mimicked vaccination’s effects by administering keyhole limpet hemocyanin (KLH ) to CD1 male mice and used their sperm for in vitro fertilization (IVF). Two-cell embryos after IVF with spermatozoa from control (C) or KLH-treated (Im) male mice were transferred to surrogate mothers mated with vasectomized control (C) or KLH-treated (Im) male mice, resulting in four experimental groups: C–C, Im–C, C–Im, and Im–Im. The pre-implantation losses were significantly lower in the Im–C group than in the C–Im group. At the same time, the resorption rates reduced markedly in the C–Im compared to the Im–C group. Embryo and placenta weights were significantly higher in the Im–Im group. Although the GM-CSF levels were lower in the amniotic fluid of the gestating surrogate mothers in the Im–Im group, they were strongly correlated with embryo mass. The number–size trade-off was only significant in the Im–Im group. This suggests a positive, cooperative effect of spermatozoa and seminal fluid from immune-primed males on embryo growth and the optimal distribution of surrogate mother maternal resources despite the negative impact of males’ antigenic challenge on the IVF success rate.     

PBT blends with rigid polymer and elastomer inclusions: the effect of component type and reactivity on mechanical behaviour

The present study shows the potential of the poly(butylene terephthalate) (PBT) matrix to form ternary blends with well‐balanced properties, analogous to Polyamide 6 (PA6) systems with a very fine (<100 nm) separately dispersed rigid polymer (poly(styrene‐co‐maleic anhydride)) and elastomer (maleated ethylene‐propylene elastomer). The use in PBT blends of maleated components analogous to those in the PA6 systems was much less effective, due to the presence of larger particles. Enhancement of all properties, including toughness, was found in the case of a blend containing at least one component with epoxide groups, such as rigid styrene‐glycidyl methacrylate copolymer or elastomeric poly[(ethylene)‐co‐(methyl acrylate)‐co‐(glycidyl methacrylate)]. In this case, the reactive compatibilization of the epoxy‐group‐containing component caused refinement of particle size of the other component due to enhanced viscosity. As a result, more advantageous micromechanical behaviour of this ternary in comparison with the binary system occurs. The PBT matrix offers a similar potential to PA6 in synergistic influencing of both well‐dispersed phases. This work supports the universality of rigid polymer‐elastomer combination for the enhancement of the properties of pseudoductile polymers. Copyright © 2004 Society of Chemical Industry     

Monoclonal antibody R5 for detection of putatively coeliac-toxic gliadin peptides

Monoclonal antibody R5 against rye secalin was recently suggested to be useful in analysis of gluten in food. The epitope specificity of R5 was characterized and compared with those of eight other monoclonal antibodies (mabs) against gliadins (gli) and secalins. Mabs were tested for binding to synthetic peptides spanning in overlapping manner sequences of gli. In a luminescence assay R5 bound to all peptides from the N-terminal part of α-type gli hitherto known to induce in sensitive patients with coeliac disease after in vivo instillation. Thus, R5 proves to be very useful for gluten analysis. Sequences QQPFP, QQQFP, LQPFP, and QLPFP were bound most strongly. Substitution of glutamine by glutamic acid in the epitope may decrease binding of R5 dependent on surrounding amino acids. One of the positions of the substitutions diminishing antibody binding was a typical site of attack of tissue transglutaminase, the enzyme converting by deamidation cereal prolamins into their disease active form. Investigation of eight other mabs against gli and secalins showed binding properties very similar to R5. We speculate the sequence QQQ/PFP seems to represent an immunodominant structure in prolamins. An erratum to this article can be found at     

Bestimmung der Zerst?rung von Trypsininhibitoren w?hrend der Sojabohnenentbitterung

Zusammenfassung Die Untersuchung der Proteolyse durch Trypsin bei unterschiedlichen Konzentrationen von Sojaextrakten ermöglicht eine genauere Bestimmung der Antitrypsin Aktivität als die üblichen Methoden. Im Laufe der Entbitterung durch Wasserdampf werden Trypsininhibitoren fast völlig inaktiviert; beim trockenen Erhitzen ist jedoch die Inaktivierung sehr langsam. Zwischen den Resultaten der Bestimmung der Antitrypsin-und der Uresse-Aktivität ist die Korrelation gut, wenn die Inaktivierung in nassem Millieu verläuft, in trockenem Material wird die Urease beim Erhitzen wesentlich schneller als die Trypsininhibitoren inaktiviert.     

A mechanistic study of methyl parathion hydrolysis by a bifunctional organoclay

The mechanism for the hydrolysis of methyl parathion (MP) by a bifunctional quaternary-ammonium based long-chained organclay(LCOC) containing an alkylamine (-CH2CH2-NH2) headgroup was elucidated. The pathway of the catalytic hydrolysis of methyl parathion by the LCOC was defined by following the effect of replacing H20 with D20, by replacing the primary amino headgroup by a tertiary amino group, and by a detailed mathematical analysis of the proposed reaction scheme. A phosphorothioate isomer of MP was formed in the presence of the LCOC as an intermediate reaction product, initially increasing in concentration and then disappearing. The isotope effect was minimal and substituting a tertiary amine in the LCOC increased the rate of MP hydrolysis. A mechanism is proposed in which hydrolysis of MP can proceed via both a direct route (specific base hydrolysis) and through the formation of the isomer which then undergoes specific base hydrolysis more rapidly than the parent MP. The relative importance of each pathway is a function of pH with the direct hydrolysis of MP being predominant at higher pH values (pH > 10) and the isomer intermediate pathway predominating at lower pH values (pH approximately 8-10).     

Persistent organic pollutants in ringed seals from the Russian Arctic

Organochlorine compounds total DDT (ΣDDT), total HCH isomers (ΣHCH), toxaphenes (sum of Parlar 26, 50, 62), mirex, endrin, methoxychlor, total chlorinated benzenes (ΣCBz), total chlordane compounds (ΣCHL), polychlorinated biphenyls (total of 56 congeners; ΣPCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), and polybrominated diphenyl ethers (sum of 7 tri- to hepta congeners; ΣPBDEs) were analysed in the blubber of adult ringed seals from the four areas of the Russian Arctic (White Sea, Barents Sea, Kara Sea and Chukchi Sea) collected in 2001-2005. Ringed seals from the south-western part of the Kara Sea (Dikson Island — Yenisei estuary) were the most contaminated with ΣDDTs, ΣPCBs, ΣCHL, and mirex as compared with those found in the other three areas of Russian Arctic, while the highest mean concentrations of ΣHCHs and PCDD/Fs were found in the blubber of ringed seals from the Chukchi Sea and the White Sea, respectively. Among all organochlorine compounds measured in ringed seals from the European part of the Russian Arctic, concentrations of ΣDDT and ΣPCBs only were higher as compared with the other Arctic regions. Levels of all other organochlorine compounds were similar or lower than in seals from Svalbard, Alaska, the Canadian Arctic and Greenland. ΣPBDEs were found in all ringed seal samples analysed. There were no significant differences between ΣPBDE concentrations found in the blubber of ringed seals from the three studied areas of the European part of the Russian Arctic, while PBDE contamination level in ringed seals from the Chukchi Sea was 30-50 times lower. ΣPBDE levels in the blubber of seals from the European part of the Russian Arctic are slightly higher than in ringed seals from the Canadian Arctic, Alaska, and western Greenland but lower compared to ringed seals from Svalbard and eastern Greenland.