The paper presents a technique for the synthesis of molybdenum carbide using mechanical activation of carbon black, which was impregnated with a 20% aqueous solution of ammonium heptamolybdate (AHM) ...using the incipient wetness technique, in an inert medium at a 100 g acceleration of milling bodies for 30 min. The mechanically activated carbide-containing composites were calcined in an inert medium at 800 °C. The composites were examined by a range of physical methods. It was shown that the mechanically activated composite consists of molybdenum carbide, iron oxide and iron carbide (about 4–8% according to AES-ICP). The phase addition method was used to determine the quantitative content of Мо2С, which was equal to 7.2 wt% in the calcined sample. Catalytic testing of mechanically activated molybdenum carbide in the partial oxidation of methane showed that the carbide-containing catalyst provides a 48–60% conversion of methane and an 83–85% selectivity for the target product (CO).
•Technique for the synthesis of carbide-containing composites by mechanical activation in inert atmosphere were developed.•Optimal parameters of mechanical activation were chosen: acceleration of milling bodies and MA time.•Quantitative estimation of molybdenum carbide content was made.•Catalytic testing of molybdenum carbide in the partial oxidation of methane was performed.
Macroalgae have long served as bioindicators of pollution in coastal marine environments. However, conventional pollution assessment methods often take a compartmentalized approach, either focusing ...on macrophyte biological parameters or independently analyzing heavy metal and oil product bioaccumulation within them. This study establishes connections between: (1) the characteristics of chemical pollution in brown, green, and red macroalgae, (2) organic pollution in the nutrient medium, and (3) the resulting changes in phytocenosis composition and macrophyte morphological characteristics. The research was conducted in the coastal zone near the Sochi River mouth on the Black Sea coast of Russia, encompassing the urban center of the Sochi metropolitan area. Inductively Coupled Plasma (ICP) analysis quantified the accumulation levels of 60 chemical elements within macrophyte algae. The novel aspect of this study is the development of a quantitative metric for assessing the overall chemical pollution impacting the ecologically crucial macroalgae Cystoseira. This systematic approach represents a significant advancement in the comprehensive evaluation and management of coastal water quality. The study identified two contrasting accumulation patterns: (1) pollution-tolerant annual algae exhibited an exclusion mechanism for chemical elements, while (2) Cystoseira displayed a non-exclusion accumulation pattern, potentially explaining its absence in the most heavily polluted zone. This approach paves the way for establishing a standardized scale for algal chemical pollution, reflecting a range from permissible to highly hazardous levels in seawater. This will enable rapid acquisition of both qualitative and quantitative pollution data, streamline monitoring efforts, and expedite the implementation of control measures.
•Reliable organic/chemical pollution indicators in macroalgae identified.•Dominant species proportions in phytocenosis indicate pollution.•Total raw algal biomass indicates pollution.•Chemical pollution threshold for Cystoseira health identified.•Evidence found of algae's exclusion/non-exclusion element accumulation patterns.
The problem of nontransitivity of stochastic precedence relation is considered. In particular, nontransitivity is studied in the case of three and four random variables with densities given by cubic ...polynomials on the unit interval. Lower bounds for maximal probabilities and the corresponding expressions for the densities and distribution functions are obtained. Moreover, the effect of stochastic nontransitivity in application to Bayesian queueing models is studied. Namely, we compare the behavior of the traffic intensities of three and four single-server queuing systems with random service parameters and random parameters of input flows under the assumption that the latter are subject to a stochastic precedence relation.
Current research fields of metal-organic frameworks (MOFs), which are being developed in the last 5-10 years by Russian scientific institutions and universities, are generalized. The review ...encompasses the design, synthesis, topological description, and prediction of MOF properties, the development of methods for their chemical engineering and modification, their investigation by modern physicochemical techniques, and the creation of functional materials based on porous frameworks (heterogeneous catalysts, highly efficient and highly selective sorbents of the new generation, conducting materials, systems for the target drug delivery).
Although photophysical properties of Radachlorin photosensitizer (PS) were extensively studied in solutions and cells, no data is available on variations of its characteristics upon binding to serum ...albumins, which are major transporters in blood and nutrients in cell culture media.
The primary objective of this study was to analyze changes in photophysical properties of Radachlorin molecules upon their binding to human and bovine serum albumins at different microenvironment properties.
Experiments were performed using time-resolved fluorescence spectroscopy and fluorescence recovery after photobleaching. Variations in fluorescence spectra and lifetime, fluorescence anisotropy, rotational and translational diffusion of PS molecules upon binding to albumins were studied in normal, basic and acidic conditions and at different concentrations of albumin and PS molecules.
Radachlorin molecules effectively bind to both types of serum albumins, which causes changes in photophysical properties of the PS. A minor red shift of the fluorescence spectrum, an increase in fluorescence lifetime and anisotropy and substantial decrease of translational and rotational mobility of PS molecules were observed upon their binding to albumins. The analysis of rotational diffusion time provided robust evaluation of the bound fraction of PS molecules. Both the highly acidic microenvironment and increase in alcohol concentration above 40% resulted in detachment of PS molecules from albumins. Photophysical properties of Radachlorin in complexes with BSA and HSA were found to be slightly different.
Binding of Radachlorin photosensitizer to either BSA or HSA affects significantly its photophysical properties, which may also vary with microenvironment acidity and alcohol concentration.
We consider a single-line queuing system with an infinite buffer that receives two Poisson flows of customers with different intensities. Customers of the first type have preemptive priority over ...customers of the second type. In addition, at the time of the end of servicing, a high-priority customer with some probability can drop all low-priority customers in the queue. Serving both types of customers has an exponential distribution with different parameters. We show expressions for calculating stationary probabilities in this system, the probability of servicing a low-priority customer in terms of the generating function, and a formula for the average number of customers of the second type.
We present a thorough experimental investigation of fluorescence properties of Radachlorin photosensitizer in solutions of different acidity, viscosity and polarity. Experiments were performed using ...time-resolved fluorescence lifetime imaging and time-resolved analysis of polarized fluorescence. Variations of solution acidity resulted in considerable changes of Radachlorin fluorescence quantum yield and lifetime in the pH range from 4 to 7, but did not affect the rotational diffusion time, and almost did not change the quantum yield and characteristic times of singlet oxygen phosphorescence. Variations of solution polarity and viscosity were achieved by changing ethanol or methanol fraction in aqueous solution. The decrease of solution polarity resulted in nonlinear rise of Radachlorin fluorescence quantum yield and lifetime up to alcohol concentration of 50%–65%, as well as in considerable rise of singlet oxygen quantum yield and significant changes in characteristic times of its phosphorescence. Variations of solution viscosity resulted in changes of rotational diffusion time of Radachlorin molecules, which appeared to be in perfect correlation with methanol solution viscosity. Good correspondence with ethanol solution viscosity was observed only up to 50% alcohol fraction. Deviations of rotational diffusion time of Radachlorin molecules from direct proportionality with solution viscosity at higher ethanol concentrations were suggested to be due to different solvation conditions. The data obtained can give important reference points for analysis of microenvironment of Radachlorin molecules, their intracellular localization and performance in singlet oxygen generation.
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•Radachlorin fluorescence lifetime and quantum yield vary significantly with pH.•Radachlorin fluorescence quantum yield and lifetime nonlinearly depend on polarity.•Decrease of solution polarity causes rise of singlet oxygen quantum yield.•Rotational diffusion time of Radachlorin varies with solution viscosity.•Two-photon excitation provides high anisotropy of Radachlorin fluorescence.
Platinum drugs are among the most active and widely used agents in the treatment of different cancers. However, the great individual variability in both outcome and toxicity of platinum chemotherapy ...requires the identification of genetic markers that can be used to screen patients before treatment. In this study, 21 polymorphisms in 10 genes, the protein activities of which may be addressed in different aspects of cisplatin metabolism, were tested for correlations with efficacy and toxicity of cisplatin-cyclophosphamide regimen in 104 ovarian cancer patients. The glutathione S-transferase P1 (GSTP1) Ile105Val polymorphism was strongly associated with progression-free survival (chi(2)=12.12, P=0.002). The allelic status of the GSTA1 -69 C>T polymorphism correlated with the overall survival: patients with T/T genotype survived longer than C/C carriers (P=0.044). Thrombocytopenia, anemia and neuropathy were less frequent among patients with the GSTM1-null or GSTM3 intron 6 AGG/AGG genotypes. Severe neutropenia was associated with the TP53 72 Pro/Pro, XPD 312 Asp/Asn and XRCC1 399 Arg/Arg genotypes. A higher risk of nephrotoxicity was noted for patients with the heterozygous ERCC1 19007 T/C and 8092 C/A genotypes. No correlations were found between genotypes and complete tumor responses.
Celotno besedilo
Dostopno za:
DOBA, EMUNI, GIS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK
Gold nanorods (AuNRs) stabilized by cetyltrimethylammonium bromide (CTAB) were synthesized and an interaction of catecholamines (CAs) with silver ions in the presence of the obtained AuNRs was ...studied. The reaction results into formation of core-shell Au@Ag nanorods (Au@AgNRs) and leads to a hypsochromic shift of the long-wave surface plasmon resonance (SPR) band in the absorption spectrum of AuNRs. The influence of a CA structure, excess of CTAB, interaction time, pH, concentration of AuNRs, silver ions and CAs on this interaction was studied. Based on correlation of the NRs spectral characteristics with the concentration of CAs, a method for spectrophotometric determination of dobutamine, epinephrine, norepinephrine and dopamine with detection limits 27, 18, 16 and 13 μg L−1, respectively, has been developed. The method can be applied to the analysis of medicines.
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•Formation of core-shell Au@Ag nanorods under influence of catecholamines was systematically studied.•Influence of different parameters during the synthesis was evaluated.•Characterization of synthesized Au@Ag nanorods was performed.•A method for simple spectrophotometric determination of catecholamines was developed.
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