Assessing the environmental benefit of palladium-based single-atom heterogeneous catalysts for Sonogashira coupling.

The Pd-Cu catalysed Sonogashira coupling of terminal alkynes and aryl halides is a cornerstone synthetic strategy for C-C bond formation. Homogeneous organometallic systems conventionally applied are typically not reusable and require efficient downstream Pd removal steps for product purification, making it challenging to fully recover the precious metal. A holistic cradle-to-gate life cycle assessment (LCA) unveils that process footprint can be improved up to two orders of magnitude from repeated catalyst reuse. New classes of heterogeneous catalysts based on isolated metal atoms (single-atom catalysts, SACs) demonstrate promising potential to synergise the benefits of solid and molecular catalysts for efficient Pd utilisation. Here we show that using Pd atoms anchored on nitrogen-doped carbon permits full recovery of the metal and reuse of the catalyst over multiple cycles. A hybrid process using the Pd-SAC with a homogeneous CuI cocatalyst is more effective than a fully heterogeneous analogue based on a bimetallic Pd-Cu SAC, which deactivates severely due to copper leaching. In some scenarios, the LCA-based metrics demonstrate the footprint of the hybrid homogeneous-heterogeneous catalytic process is leaner than the purely homogeneous counterpart already upon single reuse. Combining LCA with experimental evaluation will be a useful guide to the implementation of solid, reusable catalysts for sustainable organic transformations.

Dynamics and Site Isolation: Keys to High Propane Dehydrogenation Performance of Silica-Supported PtGa Nanoparticles.

Nonoxidative dehydrogenation of light alkanes has seen a renewed interest in recent years. While PtGa systems appear among the most efficient catalyst for this reaction and are now implemented in production plants, the origin of the high catalytic performance in terms of activity, selectivity, and stability in PtGa-based catalysts is largely unknown. Here we use molecular modeling at the DFT level on three different models: (i) periodic surfaces, (ii) clusters using static calculations, and (iii) realistic size silica-supported nanoparticles (1 nm) using molecular dynamics and metadynamics. The combination of the models with experimental data (XAS, TEM) allowed the refinement of the structure of silica-supported PtGa nanoparticles synthesized via surface organometallic chemistry and provided a structure-activity relationship at the molecular level. Using this approach, the key interaction between Pt and Ga was evidenced and analyzed: the presence of Ga increases (i) the interaction between the oxide surface and the nanoparticles, which reduces sintering, (ii) the Pt site isolation, and (iii) the mobility of surface atoms which promotes the high activity, selectivity, and stability of this catalyst. Considering the complete system for modeling that includes the silica support as well as the dynamics of the PtGa nanoparticle is essential to understand the catalytic performances.

Machine learning powered by principal component descriptors as the key for sorted structural fit of XANES.

Modern synchrotron radiation sources and free electron laser made X-ray absorption spectroscopy (XAS) an analytical tool for the structural analysis of materials under in situ or operando conditions. Fourier approach applied to the extended region of the XAS spectrum (EXAFS) allows the estimation of the number of structural and non-structural parameters which can be refined through a fitting procedure. The near edge region of the XAS spectrum (XANES) is also sensitive to the coordinates of all the atoms in the local cluster around the absorbing atom. However, in contrast to EXAFS, the existing approaches of quantitative analysis provide no estimation for the number of structural parameters that can be evaluated for a given XANES spectrum. This problem exists both for the classical gradient descent approaches and for modern machine learning methods based on neural networks. We developed a new approach for rational fit based on principal component descriptors of the spectrum. In this work the principal component analysis (PCA) is applied to a dataset of theoretical spectra calculated a priori on a grid of variable structural parameters of a molecule or cluster. Each principal component of the dataset is related then to a combined variation of several structural parameters, similar to the vibrational normal mode. Orthogonal principal components determine orthogonal deformations that can be extracted independently upon the analysis of the XANES spectrum. Applying statistical criteria, the PCA-based fit of the XANES determines the accessible structural information in the spectrum for a given system.

[The effect of biguanide derivatives on oxidative stress in rats with hyperglycemia]. / Vozdeistvie biguanidinovykh proizvodnykh na razvitie oksidativnogo stressa pri giperglikemii u krys.

The effect of the synthetic biguanide derivatives N-[imino(1-piperidinyl)methyl]guanidine (NIPMG) and 1,3-dimethyl-5-[(carbamimidamidomethanimidoil) amino]benzoyl-1,3dicarboxylate (DCB) on the degree of proteins oxidative modification (POM) and the DNA fragmentation, the content of the lipid peroxidation primary products - conjugated dienes (CD), and the activity of glutathione antioxidant system in the liver and heart of rats with experimental hyperglycemia was investigated. Administration of the biguanides (15.0 mg/kg) to hypoglycemic rats promoted reduction of the free radical processes intensity in the studied tissues. Data about CD and POM level changes in hyperglycemic rats treated by NIPMG and DKB correlate with the results of DNA fragmentation degree evaluation. At the same time, the activity of antioxidant enzymes (glutathione peroxidase and glutathione reductase), and the reduced glutathione content in the liver and heart of rats changed toward control values. For metformin, which was used as a comparison drug, changes in the studied parameters in the same direction were also found. These results indicate the ability of the tested biguanide derivatives to exhibit a positive regulatory effect on free radical homeostasis, reducing the degree of oxidative stress at this pathology.

[The effect of the biologically active additive epiphamine on antioxidant and NADPH-generating enzymes activity under experimental cerebral ischemia/reperfusion in rats]. / Vozdeistvie BAD épifamin na aktivnost' antioksidantnykh i NADPH-generiruiushchikh fermentov pri éksperimental'noi ishemii/reperfuzii golovnogo mozga u krys.

The effect of biologically active additive with immunomodulator properties epiphamine on the activity of antioxidant (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione transferase) and NADPH-generating (glucose-6-phosphate dehydrogenase, NADP-isocitrate dehydrogenase) enzymes has been investigated at experimental cerebral ischemia/reperfusion in rats. The results obtained indicate epiphamine-induced changes of these enzymes activities towards control values. Changes in the content of lactate, a marker of the pathology development, have also been found in experimental animals under ischemia and epiphamine administration caused changes similar to those observed in the case of enzyme activities studied. In most cases, the changes were dose-dependent. Thus, epiphamine can be of considerable interest from the point of view of metabolic changes pharmacological correction at the development of the pathology accompanied by oxidative stress.

X-ray emission spectroscopy: highly sensitive techniques for time-resolved probing of cerium reactivity under catalytic conditions.

Oxygen storage materials such as ceria are used in many catalytic applications because they can reversibly bind and release oxygen. Tools are needed to observe and quantify this activity which involves a change in the cerium oxidation state and to understand the involvement of cerium in catalytic processes. To prove that cerium changes its oxidation state in the catalytic cycle the transient rates of Ce3+ formation and decay should be compared to the overall reaction rate. For such mechanistic studies the time resolution is essential as the quantification of the Ce3+ species should be faster than the reaction rate. However, it is challenging to follow the dynamic changes of the cerium oxidation state under reaction conditions, especially when the concentration of cerium atoms involved in the reaction cycle is low. In this paper, we evaluate the sensitivity of high-resolution X-ray emission-based methods for the in situ time-resolved quantification of small concentrations of Ce3+ in ceria-based materials. We demonstrate that resonant X-ray emission spectroscopy (RXES) at optimal excitation energy is more sensitive than high energy resolution off-resonant spectroscopy (HEROS) and non-resonant X-ray emission spectroscopy (non-resonant XES) and that it can track the reactivity of less than 0.3% of cerium atoms in a 1% Pt/CeO2 catalyst in a plug-flow reactor with sub-second time resolution. These results demonstrate that X-ray emission-based methods can be used as very sensitive tools and provide new insights into dynamic changes of the oxidation state in reducible oxides in a variety of applications.

[The effect of melaxen administration on the tissue oxidative status in rats with brain ischemia/reperfusion]. / Oksidativnyi status tkanei krys pri vvedenii melaksena na fone razvitiia ishemii/reperfuzii golovnogo mozga.

Melaxen administration to rats with brain ischemia/reperfusion was accompanied by a decrease of the lactate level (an organ ischemia marker), biochemiluminescence parameters characterizing the intensity of free radical processes and total antioxidant activity, the content of lipid peroxidation products, activity of superoxide dismutase and catalase, as compared with the values determined in rats with induced brain ischemia/reperfusion. Activity of aconitate hydratase, a sensitive target of free radicals action, and the citrate level in the brain and blood serum of melaxen-treated animals changed towards control values of intact animals. It is assumed that the effect of melaxen is associated with implementation of the antioxidant and protective properties of melatonin, the melaxen constituent, under conditions of post-ischemic reperfusion injury, accompanied by oxidative stress development.

[GLUTATHIONE SYSTEM ACTIVITY IN RAT TISSUES UNDER PHENYLETHYL BIGUANIDE ACTION ON THE BACKGROUND OF EXPERIMENTAL BRAIN ISCHEMIA/REPERFUSION DEVELOPMENT].

It was studied the total antioxidant activity, content of primary lipid peroxidation (LPO) products and reduced glutathione, and the activity of glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, and NADP-isocitrate dehydrogenase in rat tissues under phenylethyl biguanide (phenfor- min) action on the background of experimental brain ischemia/reperfusion development. It is stablished the analyzed parameters, increasing under ischemia/reperfusion conditions in the brain and blood serum of animals, exhibit a decrease upon the introduction of this biguanide derivative. The obtained data can be explained by a decrease in degree of mobilization of the antioxidant system--in particular, of its glutathione chain--in the pathologic state. Hence, there is a need in NADPH supply for the system functioning compared with the pathology. Thus, phenylethyl biguanide demonstrates its antioxidant and protective properties under oxidative stress development that is accompanied by accumulation of the products of free radical oxidation of biomolecules during the ischemic brain injury.

[EFFECT OF MELATONIN ON THE GLUTATHIONE ANTIOXIDANT SYSTEM ACTIVITY IN RAT TISSUES UNDER CONDITIONS OF EXPERIMENTAL RHEUMATOID ARTHRITIS.]

The influence of melatonin on the reduced glutathione content, activity of glutathione peroxidase, glutathione reductase, and glutathione transferase in blood serum, heart, liver, and skeletal muscle of rats under conditions of experimental rheumatoid arthritis development has been estimated. A change in these parameters toward normal control values under the action of hormone has been revealed. The results can be related to realization of the melatonin antioxidant and protective properties under conditions of oxidative stress accompanying the development of rheumatoid arthritis.

[The effect of 3,5-dicarbomethoxyphenylbiguanide on the activity of antioxidant enzymes].

The effect of 3,5-dicarbomethoxyphenylbiguanide, which was selected with the Prediction of Activity Spectra of Substances (PASS) computer program, on the activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione transferase in the heart and the blood serum of rats with experimental rheumatoid arthritis was investigated. The studied parameters changed towards control values when the tested compound was injected in animals with the pathology. These results can be explained by the cardioprotective and antioxidant activity of the compound. The data obtained during the study may be used for the development of new preventive and therapeutic agents for the treatment of the rheumatoid arthritis.

Effects of a Preparation Containing Pantogam, Succinic Acid, and Chitosan on Activities of the Glutathione System and NADPH-Generating Enzymes in Rat Tissues under Conditions of Cerebral Ischemia/Reperfusion.

Treatment with the complex preparation containing pantogam, succinic acid, and chitosan normalized the concentration of reduced glutathione and activities of glutathione peroxidase, glutathione reductase, and some NADPH-generating enzymes (glucose-6-phosphate dehydrogenase and NADPH-isocitrate dehydrogenase) in animals with experimental hypoxia/reperfusion of the brain. These results can be explained by suppression of free radical oxidation and normalization of the antioxidant system related to the neuroprotective, antihypoxic, and antioxidant properties of these substances, their involvement into the regulation of cell metabolism under pathological conditions accompanied by oxidative stress.

Atomically dispersed rhodium on a support: the influence of a metal precursor and a support.

The influence of the support type and the metal precursor on the dispersion of rhodium after calcination and reduction was determined. The combination of electron microscopy and X-ray absorption analysis allowed the quantification of the amount of atomically dispersed rhodium in the samples. Higher amounts of atomically dispersed rhodium atoms are obtained when metal impregnation is performed with a rhodium acetate precursor in comparison to a rhodium chloride precursor over supports of the same composition. The stability of rhodium is improved with the addition of promoters; the co-presence of samaria and ceria in the support and metal impregnation with a rhodium acetate precursor leads to the highest amount of atomically dispersed rhodium remaining after reductive treatment at 773 K.

[Effect of succinic acid derivatives and chitosan on the oxidation status of tissues in rats with cerebral ischemia/reperfusion model].

The administration of chitosan succinate and N-succinylchitosan to rats with cerebral ischemia/reperfusion model damage leads to a decrease in the level of lactate (marker of ischemic injury development), parameters of biochemiluminescence (measure of free-radical oxidation intensity), and lipid peroxodation products in animal tissues as compared to untreated (pathologic) control. The obtained results show evidence of the ability of tested drugs to decrease the degree of oxidative stress manifestation under cerebral ischemia/reperfusion conditions, which is related to the positive control effect of chitosan-based drugs on the free-radical homeostasis.

[Pathogenic effect of pandemic influenza virus H1N1 under replication in cultures of human cells].

The propagation of the pandemic influenza virus H1N1 in cultures of bronchial (Calu-3) and intestinal (Caco-2) differentiated epithelial cells of human origin was studied. The canine epithelial cell lines, MDCK-H and MDCK-2, were comparatively tested. The two human cell lines were found to be highly sensitive to the influenza pandemic strains A/Hamburg/05/09 and A/Moscow/501/2011 and maintained their replication without addition of trypsin to culture medium. Virus strains of seasonal influenza H1N1, such as A/Moscow/450/2003, A/Memphis/14/96, and laboratory strain A/PR/8/34, multiplied in these human cells in similar manner. The intracellular cleavage HA0-->HA1+HA2 by the host virus-activating protease (IAP) occurred in both human cell lines under infection with each influenza virus H1N1 including pandemic ones. Comparatively, this cleavage of all influenza H1N1 virus strains appeared to be either undetectable or low-detectible in MDCK-H and MDCK-2, respectively, thereby implying low levels of active IAP in these cells. Multiplication of pandemic and seasonal influenza H1N1 viruses in Calu-3 and Caco-2 cells caused cytopathic effect, which was accompanied with low autophagy and apoptosis events. These data allow recommending human cell lines, Calu-3 and Caco-2, for optimized isolation and passaging of clinical strains of Influenza pandemic viruses H1N1.

A von Hamos x-ray spectrometer based on a segmented-type diffraction crystal for single-shot x-ray emission spectroscopy and time-resolved resonant inelastic x-ray scattering studies.

We report on the design and performance of a wavelength-dispersive type spectrometer based on the von Hamos geometry. The spectrometer is equipped with a segmented-type crystal for x-ray diffraction and provides an energy resolution in the order of 0.25 eV and 1 eV over an energy range of 8000 eV-9600 eV. The use of a segmented crystal results in a simple and straightforward crystal preparation that allows to preserve the spectrometer resolution and spectrometer efficiency. Application of the spectrometer for time-resolved resonant inelastic x-ray scattering and single-shot x-ray emission spectroscopy is demonstrated.

[Evolutionary changes in the NA and HA genes of H3N2 influenza virus in the Moscow Region during 2003-2009].

During the winter 2009 outbreak in the Moscow Region, H3N2 influenza viruses were isolated from the nasopharyngeal washes of patients via their propagation in the human intestinal (Caco-2) and bronchial (Calu-3) epithelial cell cultures maintaining the proteolytic cleavage of HA0--> HA1+HA2 and multicycle virus replication. Analysis of the nucleotide sequences of virus RNA indicated that the 2009 viruses differed from those isolated in 2003 in 14 and 21 amino acids of the neuraminidase (NA) and hemagglutinin (HA) genes, respectively. The NA gene was 1762 nucleotides long whereas the 2003 isolates had a deletion of 66 nucleotides (22 amino acids) in the stalk region (short-stalk NA genotype) of viruses. The NA gene of the 2009 and 2003 isolates possessed an amino acid profile characterized for oseltamivir- and zanamivir-susceptible viral strains. The HA gene of the 2009 viruses contained an N-glycosylation site at Asn181 (an analog to Asn 65 numbering from a signal peptide), which correlated with the long-stalk NA gene. The 2009 viruses had Phe209 in the HA receptor binding center whereas the 2003 isolates possessed Ser209, which correlated with their differences in HA activity. Phylogenetic analysis showed that the NA genes of the 2003 and 2009 Moscow strains were located in the same genetic clade with a single common precursor while their HA genes were diverged in more genetic distance and located in different clades. Viral distribution in the phylogenetic tree indicated that the Moscow strains isolated in 2009 were not direct ancestors of those isolated in 2003; and during the period of 2003 to 2009, H3N2 influenza virus with a short-stalk NA genotype was substituted for a migrant virus possessing a long-stalk NA gene.

[Emergence of tick-borne spotted fever group rickettsiosis in Moscow].

AIM: Analysis of clinical cases of tick-borne spotted fever (TSF) group rickettsiosis in 2005 - 2010. MATERIALS AND METHODS: General clinical, biochemical and serological parameters were determined in 10 tick-borne spotted fever group rickettsiosis patients who had visited various geographical regions of the World. RESULTS: TSF group rickettsiosis diagnostic criteria, optimal serological diagnostics timing were determined. Possible diagnostic errors, features of serological diagnostics and antibacterial therapy of this nosologic form are discussed. CONCLUSION: Indication for TSF examination are primarily epidemiologic including tick attachment indication and clinical data. Serological studies are positive only in 3 - 4 weeks after the onset of the infection and thus can not be used for early diagnostics.

Effects of 2,4-dimethoxyphenyl biguanide on glutathione system activity in rat tissues in brain ischemia-reperfusion.

We studied the effects of dimethoxyphenyl biguanide on glutathione peroxidase and glutathione reductase activities, level of reduced glutathione in rat tissues, and activity of some NADPH-regenerating enzymes (glucose-6-phosphate dehydrogenase and NADP-isocitrate dehydrogenase) under conditions of ischemia-reperfusion of the brain. Administration of this biguanide derivative under pathological conditions led to a decrease in the analyzed parameters (elevated under conditions of ischemia-reperfusion) in the serum and brain tissue. The results attest to less pronounced mobilization of the glutathione system (compared to pathological state) due to antioxidant and protective properties of 2,4-dimethoxyphenyl biguanide under conditions of ischemic tissue damage associated with oxidative stress.

[Diagnostic criterion for anorexia nervosa].

Article presents a case of anorexia in 29 years old patient. Described the clinical symptoms of anorexia, the manifestations of the disease in patient; the premorbid characteristics of personality, the formation of which influences on relationships with parents.

[Treatment of tobacco dependence in patients with chronic diseases of digestive system].

The purpose of this study was to increase the effectiveness of tobacco control by improving the treatment of tobacco dependence. The article presents the data results of different methods of treatments of tobacco dependence among 135 patients with digestive diseases. As the most effective is a comprehensive approach combining psychotherapy and physiotherapy methods is designated. The possible reasons of due treatment effect absence are separately analysed: a sharp severity of tobacco withdrawal syndrome, inadequate primary motivation of smoking refusal, premorbid personality characteristics, a pathological variant of response to disease.