Development of catalysts for hydrogen generation from hydride compounds

Catalytic hydrolysis of NaBH₄ and NH₃BH₃ has been studied. It was shown that the nature of the support and the active component of the catalyst affect the H₂ generation rate. Despite similar sizes of rhodium particles formed on the surface of different supports (γ-Al₂O₃, TiO₂, carbon), their reactivity is different. Rh/TiO₂ with low rhodium concentration (1 wt.%) is the most active catalyst both in the hydrolysis of NaBH₄ and NH₃BH₃. The obtained results show that the rhodium chloride interaction with titania determines the reactivity of rhodium particles formed under action of NaBH₄ medium. TEM, DRS UV–vis and XPS were used to characterize the catalysts.     

Structure and Certain Properties of Hot-Pressed Boron Carbide-Based Ceramic with Calcium-Silicon Additive

The influence which the composition of powder mixtures, the treatment conditions which the mixtures are subjected to, and the conditions under which the hot-pressed composite materials B₄C – (5-10 mass%) calcium-silicon are fabricated exert on the structure, nature of failure, and mechanical properties of these materials is investigated. Optimum properties are possessed by material containing 10 mass% of addition. It is shown that the structure, morphology, and dispersivity, as well as the nature of the distribution of the components that are added to the composite material (secondary phase) vary as the temperature of hot pressing changes. Maximal mechanical characteristics of the composite material (σ_bend = 560 MPa, K _1c = 4.7 MPa·m^1/2, HV = 37 GPa) are attained at hot-pressing temperatures in the range 2000-2100°C.     

Natural and Designed Toxins for Precise Therapy: Modern Approaches in Experimental Oncology

Cancer cells frequently overexpress specific surface receptors providing tumor growth and survival which can be used for precise therapy. Targeting cancer cell receptors with protein toxins is an attractive approach widely used in contemporary experimental oncology and preclinical studies. Methods of targeted delivery of toxins to cancer cells, different drug carriers based on nanosized materials (liposomes, nanoparticles, polymers), the most promising designed light-activated toxins, as well as mechanisms of the cytotoxic action of the main natural toxins used in modern experimental oncology, are discussed in this review. The prospects of the combined therapy of tumors based on multimodal nanostructures are also discussed.     

Studies of porous polymer gels. I. One-step suspension technique for preparation of moderately crosslinked methacrylic acid gels

A new method of preparation of carboxyl cation exchangers directly from methacrylic acid and divinylbenzene is described. A suspension technique with a concentrated aqueous calcium chloride solution as the water phase was used. n-Octane and toluene were inert diluents of the monomers. The copolymers obtained have high ion-exchange capacity (9.6–10.6 mequ./g) and porous structure.     

A Role of DNA Methylation within the CYP17A1 Gene in the Association of Genetic and Environmental Risk Factors with Stress-Related Manifestations of Schizophrenia

As genetic and environmental influences on schizophrenia might converge on DNA methylation (DNAm) within loci which are both associated with the disease and implicated in response to environmental stress, we examined whether DNAm within CYP17A1, a hypothalamus–pituitary–adrenal axis gene which is situated within the schizophrenia risk locus 10q24.32, would mediate genetic and environmental effects on stress-related schizophrenia symptoms. DNAm within an exonic–intronic fragment of CYP17A1 was assessed in the blood of 66 schizophrenia patients and 63 controls using single-molecule real-time bisulfite sequencing. Additionally, the VNTR polymorphism of the AS3MT gene, a plausible causal variant within the 10q24.32 locus, was genotyped in extended patient and control samples (n = 700). The effects of local haplotype, VNTR and a polyenviromic risk score (PERS) on DNAm, episodic verbal memory, executive functions, depression, and suicidality of patients were assessed. Haplotype and PERS differentially influenced DNAm at four variably methylated sites identified within the fragment, with stochastic, additive, and allele-specific effects being found. An allele-specific DNAm at CpG-SNP rs3781286 mediated the relationship between the local haplotype and verbal fluency. Our findings do not confirm that the interrogated DNA fragment is a place where genetic and environmental risk factors converge to influence schizophrenia symptoms through DNAm.     

Molecular Characteristics,Receptor Specificity,and Pathogenicity of Avian Influenza Viruses Isolated from Wild Ducks in Russia

Avian influenza viruses (AIV) of wild ducks are known to be able to sporadically infect domestic birds and spread along poultry. Regular surveillance of AIV in the wild is needed to prepare for potential outbreaks. During long-year monitoring, 46 strains of AIV were isolated from gulls and mallards in Moscow ponds and completely sequenced. Amino acid positions that affect the pathogenicity of influenza viruses in different hosts were tested. The binding affinity of the virus for receptors analogs typical for different hosts and the pathogenicity of viruses for mice and chickens were investigated. Moscow isolates did not contain well-known markers of pathogenicity and/or adaptation to mammals, so as a polybasic cleavage site in HA, substitutions of 226Q and 228G amino acids in the receptor-binding region of HA, and substitutions of 627E and 701D amino acids in the PB2. The PDZ-domain ligand in the NS protein of all studied viruses contains the ESEV or ESEI sequence. Although several viruses had the N66S substitution in the PB1-F2 protein, all Moscow isolates were apathogenic for both mice and chickens. This demonstrates that the phenotypic manifestation of pathogenicity factors is not absolute but depends on the genome context.     

Conjugates of Methylene Blue with Cycloalkaneindoles as New Multifunctional Agents for Potential Treatment of Neurodegenerative Disease

The development of multi-target-directed ligands (MTDLs) would provide effective therapy of neurodegenerative diseases (ND) with complex and nonclear pathogenesis. A promising method to create such potential drugs is combining neuroactive pharmacophoric groups acting on different biotargets involved in the pathogenesis of ND. We developed a synthetic algorithm for the conjugation of indole derivatives and methylene blue (MB), which are pharmacophoric ligands that act on the key stages of pathogenesis. We synthesized hybrid structures and performed a comprehensive screening for a specific set of biotargets participating in the pathogenesis of ND (i.e., cholinesterases, NMDA receptor, mitochondria, and microtubules assembly). The results of the screening study enabled us to find two lead compounds (4h and 4i) which effectively inhibited cholinesterases and bound to the AChE PAS, possessed antioxidant activity, and stimulated the assembly of microtubules. One of them (4i) exhibited activity as a ligand for the ifenprodil-specific site of the NMDA receptor. In addition, this lead compound was able to bypass the inhibition of complex I and prevent calcium-induced mitochondrial depolarization, suggesting a neuroprotective property that was confirmed using a cellular calcium overload model of neurodegeneration. Thus, these new MB-cycloalkaneindole conjugates constitute a promising class of compounds for the development of multitarget neuroprotective drugs which simultaneously act on several targets, thereby providing cognitive stimulating, neuroprotective, and disease-modifying effects.