Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 27
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Biochemistry (Mosc) ; 89(1): 184-195, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38467554

RESUMO

Cell migration is largely determined by the type of protrusions formed by the cell. Mesenchymal migration is accomplished by formation of lamellipodia and/or filopodia, while amoeboid migration is based on bleb formation. Changing of migrational conditions can lead to alteration in the character of cell movement. For example, inhibition of the Arp2/3-dependent actin polymerization by the CK-666 inhibitor leads to transition from mesenchymal to amoeboid motility mode. Ability of the cells to switch from one type of motility to another is called migratory plasticity. Cellular mechanisms regulating migratory plasticity are poorly understood. One of the factors determining the possibility of migratory plasticity may be the presence and/or organization of vimentin intermediate filaments (VIFs). To investigate whether organization of the VIF network affects the ability of fibroblasts to form membrane blebs, we used rat embryo fibroblasts REF52 with normal VIF organization, fibroblasts with vimentin knockout (REF-/-), and fibroblasts with mutation inhibiting assembly of the full-length VIFs (REF117). Blebs formation was induced by treatment of cells with CK-666. Vimentin knockout did not lead to statistically significant increase in the number of cells with blebs. The fibroblasts with short fragments of vimentin demonstrate the significant increase in number of cells forming blebs both spontaneously and in the presence of CK-666. Disruption of the VIF organization did not lead to the significant changes in the microtubules network or the level of myosin light chain phosphorylation, but caused significant reduction in the focal contact system. The most pronounced and statistically significant decrease in both size and number of focal adhesions were observed in the REF117 cells. We believe that regulation of the membrane blebbing by VIFs is mediated by their effect on the focal adhesion system. Analysis of migration of fibroblasts with different organization of VIFs in a three-dimensional collagen gel showed that organization of VIFs determines the type of cell protrusions, which, in turn, determines the character of cell movement. A novel role of VIFs as a regulator of membrane blebbing, essential for manifestation of the migratory plasticity, is shown.


Assuntos
Adesões Focais , Filamentos Intermediários , Ratos , Animais , Filamentos Intermediários/metabolismo , Adesões Focais/metabolismo , Vimentina/genética , Vimentina/metabolismo , Vimentina/farmacologia , Microtúbulos/metabolismo , Movimento Celular , Extensões da Superfície Celular/metabolismo
2.
Aging (Albany NY) ; 15(18): 9293-9309, 2023 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-37742294

RESUMO

Target discovery is crucial for the development of innovative therapeutics and diagnostics. However, current approaches often face limitations in efficiency, specificity, and scalability, necessitating the exploration of novel strategies for identifying and validating disease-relevant targets. Advances in natural language processing have provided new avenues for predicting potential therapeutic targets for various diseases. Here, we present a novel approach for predicting therapeutic targets using a large language model (LLM). We trained a domain-specific BioGPT model on a large corpus of biomedical literature consisting of grant text and developed a pipeline for generating target prediction. Our study demonstrates that pre-training of the LLM model with task-specific texts improves its performance. Applying the developed pipeline, we retrieved prospective aging and age-related disease targets and showed that these proteins are in correspondence with the database data. Moreover, we propose CCR5 and PTH as potential novel dual-purpose anti-aging and disease targets which were not previously identified as age-related but were highly ranked in our approach. Overall, our work highlights the high potential of transformer models in novel target prediction and provides a roadmap for future integration of AI approaches for addressing the intricate challenges presented in the biomedical field.


Assuntos
Idioma , Estudos Prospectivos , Bases de Dados Factuais
3.
Nanomaterials (Basel) ; 13(15)2023 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-37570494

RESUMO

In this study, we proposed photocatalysts based on graphite-like carbon nitride with a low content (0.01-0.5 wt.%) of noble metals (Pd, Rh) for hydrogen evolution under visible light irradiation. As precursors of rhodium and palladium, labile aqua and nitrato complexes [Rh2(H2O)8(µ-OH)2](NO3)4∙4H2O and (Et4N)2[Pd(NO3)4], respectively, were proposed. To obtain metallic particles, reduction was carried out in H2 at 400 °C. The synthesized photocatalysts were studied using X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy and high-resolution transmission electron microscopy. The activity of the photocatalysts was tested in the hydrogen evolution from aqueous and aqueous alkaline solutions of TEOA under visible light with a wavelength of 428 nm. It was shown that the activity for the 0.01-0.5% Rh/g-C3N4 series is higher than in the case of the 0.01-0.5% Pd/g-C3N4 photocatalysts. The 0.5% Rh/g-C3N4 sample showed the highest activity per gram of catalyst, equal to 3.9 mmol gcat-1 h-1, whereas the most efficient use of the metal particles was found over the 0.1% Rh/g-C3N4 photocatalyst, with the activity of 2.4 mol per gram of Rh per hour. The data obtained are of interest and can serve for further research in the field of photocatalytic hydrogen evolution using noble metals as cocatalysts.

4.
Inorg Chem ; 62(32): 12625-12629, 2023 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-37523240

RESUMO

In order to prepare the first lanthanide coordination polymers (CPs) based on ditopic sulfide ligands, benzo[1,2-d:4,5-d']bisthiazole-2,6(3H,7H)-dithione (H2L) was used as a linker. The reactions of lanthanide silylamides Ln[N(SiMe3)2]3 (Ln = Nd, Gd, Er, and Yb) with H2L result in the formation of soluble dimethyl sulfoxide (DMSO) ionic salts [Ln(DMSO)8][L]1.5 [Ln = Nd (1), Gd (2), Er (3), and Yb (4)]. Due to the lack of coordination of anionic ligands, compounds 1, 3, and 4 do not show sensitized metal-centered photoluminescence (PL), while Gd compound 2 shows weak phosphorescence at 77 K. It was found that the heating of 1 in a 1:9 DMSO/1,4-dioxane mixture leads to the formation of large crystals of 2D CP [Nd(DMSO)3L1.5·0.5diox]n (5), where deprotonated dithione H2L plays the role of a ditopic linker. This linker acts as an "antenna" in compound 5, providing an intense near-infrared (NIR) PL of Nd3+ ion upon near-UV and blue-light excitation. The application of a synthetic protocol similar to that of compounds 2-4 led to the formation of amorphous compounds [Ln(DMSO)3L1.5·0.5diox]n [Ln = Gd (6), Er (7), and Yb (8)], whose PL properties significantly differ from those of the parental ionic salts. In the case of Yb polymer 8, the PL excitation spectra are shifted to the red region due to a low-energy ligand-to-metal charge-transfer state. The synthesized compounds 5-8 are the first examples of lanthanide CPs using soft-base ditopic linkers in their structures.

5.
Inorg Chem ; 62(24): 9732-9748, 2023 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-37291758

RESUMO

A combination of multinuclear nuclear magnetic resonance spectroscopy and theoretical calculation based on density functional theory was used for a speciation study of Pt in solutions prepared either by the interaction of [Pt(OH)6]2- with gaseous CO2 in an alkaline solution of platinum(IV) hydroxide ([Pt(OH)4(H2O)2]) or by the dissolution of [Pt(OH)4(H2O)2] in an aqueous KHCO3 solution. The formed solutions contained coexisting Pt(IV) carbonato complexes with κ1- and κ2-coordination modes. The gradual condensation of mononuclear Pt species in such bicarbonate solutions resulted in the formation of PtO2 nanoparticles aggregating into a solid precipitate on prolonged aging. The deposition of PtO2 particles from bicarbonate solutions was adapted for the preparation of Pt-containing heterogeneous catalysts: bimetallic Pt-Ni catalysts were prepared using various supporting materials (CeO2, SiO2, and g-C3N4) and tested for the activity in hydrazine-hydrate decomposition. All prepared materials showed high selectivity with respect to H2 production from the hydrazine-hydrate with PtNi/CeO2 showing the highest rate of H2 evolution. In the long-range evaluation, the PtNi/CeO2 catalyst operating at 50 °C showed an exceptional turnover number value of 4600 producing hydrogen at a 97% selectivity level and with a mean turnover frequency value of about 470 h-1. In the case of the PtNi/g-C3N4 catalyst, for the first time, the photodriven decomposition of hydrazine-hydrate was shown to enhance the productivity of the catalyst by 40%.

6.
Aging (Albany NY) ; 15(11): 4649-4666, 2023 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-37315204

RESUMO

Aging is a complex and multifactorial process that increases the risk of various age-related diseases and there are many aging clocks that can accurately predict chronological age, mortality, and health status. These clocks are disconnected and are rarely fit for therapeutic target discovery. In this study, we propose a novel approach to multimodal aging clock we call Precious1GPT utilizing methylation and transcriptomic data for interpretable age prediction and target discovery developed using a transformer-based model and transfer learning for case-control classification. While the accuracy of the multimodal transformer is lower within each individual data type compared to the state of art specialized aging clocks based on methylation or transcriptomic data separately it may have higher practical utility for target discovery. This method provides the ability to discover novel therapeutic targets that hypothetically may be able to reverse or accelerate biological age providing a pathway for therapeutic drug discovery and validation using the aging clock. In addition, we provide a list of promising targets annotated using the PandaOmics industrial target discovery platform.


Assuntos
Perfilação da Expressão Gênica , Aprendizado de Máquina
7.
Life (Basel) ; 13(1)2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36676113

RESUMO

Unique natural objects, such as the caves of the Gobustan National Historical and Artistic Preserve, are also of great cultural and historical value due to rock art and sites of ancient people. A favorable microclimate makes these habitats convenient for colonization by microbiota, including phototrophs. In arid regions with intense seasonal fluctuations of microclimatic parameters, the conditions for survival are the least favorable; therefore, it becomes especially important to determine the composition of communities that are the most adapted to specific conditions. This work aimed to identify the biodiversity of communities of caves and grottoes of the Gobustan Reserve. The studies were carried out in July 2019. Samples were analyzed for cyanobacteria and algae by microscopy and cultivation methods, microfungi were isolated by soil dilution, and the fouling glass method was also used. In total, 29 taxa of cyanobacteria and algae, 18 taxa of fungi, and 3 species of mosses were identified. The studied habitats were dominated by the algae Chlorella vulgaris, Aphanocapsa sp., and Stichococcus bacillaris; the subdominants were Jaaginema subtilissimum, Leptolyngbya tenuis, Chlorococcum minutum, and Humidophila contenta. Microfungi had the highest occurrence of Aspergillus niger, Aureobasidium pullulans, Alternaria alternata, and Talaromyces ruber. It was noted that cyanobacteria dominated in morphologically differentiated biofilms and green algae on the rocks. The greatest number of microfungi was found in the aphotic zone and bryophyte tufts. The dominance of green algae is atypical for most caves of other regions and may be associated with intense lighting of habitats. The absence of protonema is a consequence of the aridity and low moisture content of the substrates.

8.
Materials (Basel) ; 16(2)2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36676428

RESUMO

In this study, the crystalline structure and particle shape of Cd1-xMnxS (x~0.3) in the composite photocatalysts prepared by hydrothermal synthesis at different temperatures (T = 80, 100, 120, and 140 °C) were analyzed. Along with mixed Cd-Mn sulfide, the catalysts contain a small amount of ß-Mn3O4. XRD patterns of (Cd,Mn)S have features inherent to both cubic zinc blende and hexagonal wurtzite structure. Moreover, XRD peaks are anisotropically broadened. First, the heterogeneous (or two-phased) model was considered by the commonly used Rietveld method. Phase ratio, average crystallite sizes, and strains for both phases were formally determined. However, it was shown that this model is not correct because relatively narrow and broad peaks cannot be fitted simultaneously. Then, the homogeneous model was tested by Debye Function Analysis. This model assumes that particles are statistically homogeneous, but each particle contains lamellar intergrowth of zinc blende and wurtzite modifications. The probability of stacking faults, as well as the average radii of spherical and ellipsoidal particles, were varied. It was shown that nanocrystalline Cd0.7Mn0.3S particles have an ellipsoidal shape. Ellipsoids are elongated along the direction normal to the plane of defects. An increase in the hydrothermal synthesis temperature from 80 °C to 140 °C leads to an enlargement of particles and a gradual decrease in the probability of stacking faults in the wurtzite structure from 0.47 to 0.36. Therefore, with increasing temperature, the structure of (Cd,Mn)S nanoparticles transforms from almost random polytype cubic/hexagonal (ZB:WZ = 47:53) to a preferably hexagonal structure (ZB:WZ = 36:64). Mn2+ ions facilitate CdS phase transformation from zinc blende to wurtzite structure. There is no direct correlation between the structure and photocatalytic activity.

9.
Materials (Basel) ; 15(22)2022 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-36431512

RESUMO

In this work, new photocatalysts based on Cd1-xMnxS sulfide solid solutions were synthesized by varying the fraction of MnS (x = 0.4, 0.6, and 0.8) and the hydrothermal treatment temperature (T = 100, 120, 140, and 160 °C). The active samples were modified with Pt and NiS co-catalysts. Characterization was performed using various methods, including XRD, XPS, HR TEM, and UV-vis spectroscopy. The photocatalytic activity was tested in hydrogen evolution from aqueous solutions of Na2S/Na2SO3 and glucose under visible light (425 nm). When studying the process of hydrogen evolution using an equimolar mixture of Na2S/Na2SO3 as a sacrificial agent, the photocatalysts Cd0.5Mn0.5S/Mn(OH)2 (T = 120 °C) and Cd0.4Mn0.6S (T = 160 °C) demonstrated the highest activity among the non-modified solid solutions. The deposition of NiS co-catalyst led to a significant increase in activity. The best activity in the case of the modified samples was shown by 0.5 wt.% NiS/Cd0.5Mn0.5S (T = 120 °C) at the extraordinary level of 34.2 mmol g-1 h-1 (AQE 14.4%) for the Na2S/Na2SO3 solution and 4.6 mmol g-1 h-1 (AQE 2.9%) for the glucose solution. The nickel-containing samples possessed a high stability in solutions of both sodium sulfide/sulfite and glucose. Thus, nickel sulfide is considered an alternative to depositing precious metals, which is attractive from an economic point of view. It worth noting that the process of photocatalytic hydrogen evolution from sugar solutions by adding samples based on Cd1-xMnxS has not been studied before.

10.
Nanomaterials (Basel) ; 12(18)2022 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-36144894

RESUMO

In this study, we have proposed titania-based photocatalysts modified with copper compounds for hydrogen evolution. Thermal pre-treatment of commercial TiO2 Degussa P25 (DTiO2) and Hombifine N (HTiO2) in the range from 600 to 800 °C was carried out followed by the deposition of copper oxides (1-10 wt. % of Cu). The morphology and chemical state of synthesized photocatalysts were studied using X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and XANES/EXAFS X-ray absorption spectroscopy. Photocatalytic activity was tested in the hydrogen evolution from aqueous solutions of glycerol under ultraviolet (λ = 381 nm) and visible (λ = 427 nm) light. The photocatalysts 2% CuOx/DTiO2 T750 and 5% CuOx/DTiO2 T700 showed the highest activity under UV irradiation (λ = 380 nm), with the rate of H2 evolution at the level of 2.5 mmol (H2) g-1 h-1. Under the visible light irradiation (λ = 427 nm), the highest activity of 0.6 mmol (H2) g-1 h-1 was achieved with the 5% CuOx/DTiO2 T700 photocatalyst. The activity of these photocatalysts is 50% higher than that of the platinized 1% Pt/DTiO2 sample. Thus, it was shown for the first time that a simple heat treatment of a commercial titanium dioxide in combination with a deposition of non-noble metal particles led to a significant increase in the activity of photocatalysts and made it possible to obtain materials that were active in hydrogen production under visible light irradiation.

11.
ACS Appl Mater Interfaces ; 14(31): 35600-35612, 2022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-35881890

RESUMO

A combination of the exceptional stability of fac-[Ir(H2O)3(NO2)3] together with thermolability of nitro and aqua ligands and high solubility in various solvents makes it promising as a brand-new chlorine-free precursor of iridium for the preparation of heterogeneous catalysts. In the current work, a new technique of fac-[Ir(H2O)3(NO2)3] preparation based on hydrothermal treatment of (NH4)3[Ir(NO2)6] was developed. For this purpose, the influence of reaction parameters such as the reaction time, temperature, and pH of the solution on the process of hexanitroiridate salt hydrolysis was investigated. The synthesized fac-[Ir(H2O)3(NO2)3] solution in this optimized way was used for the preparation of the series of Ir/g-C3N4 catalysts, which were evaluated in the water oxidation reaction with NaIO4 utilized as a sacrificial reagent. A 20-fold enhancement of the oxygen evolution reaction (OER) activity was found to take place under visible light (λ = 411 nm) illumination of the systems. The highest rate of the photoinduced OER per iridium center was achieved by the Ir0.005/g-C3N4 (air, 400°C) catalyst with an exceptional turnover frequency value of 967 min-1 approaching the activity of known homogeneous iridium OER catalysts. The leaching experiments have shown that aquated Ir species are generated in a solution after prolonged functioning of the catalysts. Despite this, in the closed system the photodriven OER activity persists at a steady-state level evidencing an equilibrium achieved between dissolved and anchored Ir species forming catalytic tandem with the g-C3N4.

12.
Inorg Chem ; 61(25): 9667-9684, 2022 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-35700060

RESUMO

The systematic study of the platinum speciation in sulfuric acid solutions of platinum (IV) hydroxide {[Pt(OH)4(H2O)2], HHPA} was performed with the use of a combination of methods. Depending on the prevailing Pt form, the three regions of H2SO4 concentration were marked: (1) up to 3 M H2SO4 forms unstable solutions gradually generating the PtO2·xH2O particles; (2) 4-12 M H2SO4, where the series of mononuclear aqua-sulfato complexes ([Pt(SO4)n(H2O)6-n]4-2n, where n = 0···4) dominate; and (3) 12 M and above, where, along with [Pt(SO4)n(H2O)6-n]4-2n species, the polynuclear Pt(IV) species and complexes with a bidentate coordination mode of the sulfato ligand are formed. For the first time, the salts of the aqua-hydroxo Pt(IV) cation [Pt(OH)2(H2O)4]SO4 (triclinic and monoclinic phases) were isolated and studied with a combination of methods, including the single-crystal X-ray diffraction. The formation of PtO2·xH2O particles in sulfuric acid solutions (1-3 M) of HHPA and their spectral characteristics and morphology were studied. The deposition of PtO2·xH2O was highlighted as a convenient method to prepare various Pt-containing heterogeneous catalysts. This possibility was illustrated by the preparation of Pt/g-C3N4 catalysts, which show an excellent performance in catalytic H2 generation under visible light irradiation with a quantum efficiency up to 5% and a rate of H2 evolution up to 6.2 mol·h-1 per gram of loaded platinum.

13.
Nanomaterials (Basel) ; 12(9)2022 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-35564293

RESUMO

In this study, TiO2-based photocatalysts modified with Pt and Cu/CuOx were synthesized and studied in the photocatalytic reduction of CO2. The morphology and chemical states of synthesized photocatalysts were studied using UV-Vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. A series of light-emitting diodes (LEDs) with maximum intensity in the range of 365-450 nm was used to determine the action spectrum of photocatalysts. It is shown for, the first time, that the pre-calcination of TiO2 at 700 °C and the use of Cu/CuOx instead of Pt allow one to design a highly efficient photocatalyst for CO2 transformation shifting the working range to the visible light (425 nm). Cu/CuOx/TiO2 (calcined at 700 °C) shows a rate of CH4 formation of 1.2 ± 0.1 µmol h-1 g-1 and an overall CO2 reduction rate of 11 ± 1 µmol h-1 g-1 (at 425 nm).

14.
Int J Mol Sci ; 24(1)2022 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-36613789

RESUMO

Currently, the synthesis of active photocatalysts for the evolution of hydrogen, including photocatalysts based on graphite-like carbon nitride, is an acute issue. In this review, a comprehensive analysis of the state-of-the-art studies of graphic carbon nitride as a photocatalyst for hydrogen production under visible light is presented. In this review, various approaches to the synthesis of photocatalysts based on g-C3N4 reported in the literature were considered, including various methods for modifying and improving the structural and photocatalytic properties of this material. A thorough analysis of the literature has shown that the most commonly used methods for improving g-C3N4 properties are alterations of textural characteristics by introducing templates, pore formers or pre-treatment method, doping with heteroatoms, modification with metals, and the creation of composite photocatalysts. Next, the authors considered their own detailed study on the synthesis of graphitic carbon nitride with different pre-treatments and respective photocatalysts that demonstrate high efficiency and stability in photocatalytic production of hydrogen. Particular attention was paid to describing the effect of the state of the platinum cocatalyst on the activity of the resulting photocatalyst. The decisive factors leading to the creation of active materials were discussed.


Assuntos
Luz , Nitrilas , Nitrilas/química , Hidrogênio/química
15.
PLoS Comput Biol ; 17(7): e1009183, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34260589

RESUMO

Coronavirus disease 2019 (COVID-19) is an acute infection of the respiratory tract that emerged in December 2019 in Wuhan, China. It was quickly established that both the symptoms and the disease severity may vary from one case to another and several strains of SARS-CoV-2 have been identified. To gain a better understanding of the wide variety of SARS-CoV-2 strains and their associated symptoms, thousands of SARS-CoV-2 genomes have been sequenced in dozens of countries. In this article, we introduce COVIDomic, a multi-omics online platform designed to facilitate the analysis and interpretation of the large amount of health data collected from patients with COVID-19. The COVIDomic platform provides a comprehensive set of bioinformatic tools for the multi-modal metatranscriptomic data analysis of COVID-19 patients to determine the origin of the coronavirus strain and the expected severity of the disease. An integrative analytical workflow, which includes microbial pathogens community analysis, COVID-19 genetic epidemiology and patient stratification, allows to analyze the presence of the most common microbial organisms, their antibiotic resistance, the severity of the infection and the set of the most probable geographical locations from which the studied strain could have originated. The online platform integrates a user friendly interface which allows easy visualization of the results. We envision this tool will not only have immediate implications for management of the ongoing COVID-19 pandemic, but will also improve our readiness to respond to other infectious outbreaks.


Assuntos
COVID-19/epidemiologia , Computação em Nuvem , Biologia Computacional/métodos , Interface Usuário-Computador , COVID-19/genética , COVID-19/fisiopatologia , COVID-19/virologia , Humanos , Fatores de Risco , SARS-CoV-2/genética , Índice de Gravidade de Doença
16.
Nanomaterials (Basel) ; 11(2)2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33535500

RESUMO

A series of solid solutions of cadmium and manganese sulfides, Cd1-xMnxS (x = 0-0.35), and composite photocatalysts, CdS-ß-Mn3O4-MnOOH, were synthesized by precipitation with sodium sulfide from soluble cadmium and manganese salts with further hydrothermal treatment at 120 °C. The obtained photocatalysts were studied by the X-ray diffraction method (XRD), UV-vis diffuse reflectance spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and N2 low temperature adsorption. The photocatalysts were tested in hydrogen production using a Na2S/Na2SO3 aqueous solution under visible light (λ = 450 nm). It was shown for the first time that both kinds of photocatalysts possess high activity in hydrogen evolution under visible light. The solid solution Cd0.65Mn0.35S has an enhanced photocatalytic activity due to its valence and conduction band position tuning, whereas the CdS-ß-Mn3O4-MnOOH (40-60 at% Mn) samples were active due to ternary heterojunction formation. Further, the composite CdS-ß-Mn3O4-MnOOH photocatalyst had much higher stability in comparison to the Cd0.65Mn0.35S solid solution. The highest activity was 600 mmol g-1 h-1, and apparent quantum efficiency of 2.9% (λ = 450 nm) was possessed by the sample of CdS-ß-Mn3O4-MnOOH (40 at% Mn).

17.
RSC Adv ; 11(60): 37966-37980, 2021 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-35498100

RESUMO

Ternary composite photocatalysts based on titania and solid solutions of CdS and ZnS were prepared and studied by a set of physicochemical methods including XRD, XPS, HRTEM, UV-vis spectroscopy, and electrochemical tests. Two synthetic techniques of platinization of Cd1-x Zn x S/TiO2 were compared. In the first case, platinum was deposited on the surface of synthesized Cd1-x Zn x S (x = 0.2-0.3)/TiO2 P25; in the second one, Cd1-x Zn x S (x = 0.2-0.3) was deposited on the surface of Pt/TiO2 P25. The photocatalytic properties of the obtained samples were compared in the hydrogen evolution from TEOA aqueous solution under visible light (λ = 425 nm). The Cd1-x Zn x S (10-50 wt%; x = 0.2-0.3)/Pt (1 wt%)/TiO2 photocatalysts demonstrated much higher photocatalytic activity than the Pt (1 wt%)/Cd1-x Zn x S (10-50 wt%; x = 0.2-0.3)/TiO2 ones. It turned out that the arrangement of platinum nanoparticles precisely on the titanium dioxide surface in a composite photocatalyst makes it possible to achieve efficient charge separation according to the type II heterojunctions and, accordingly, a high rate of hydrogen formation. The highest photocatalytic activity was demonstrated by 20% Cd0.8Zn0.2S/1% Pt/TiO2 in the amount of 26 mmol g-1 h-1 (apparent quantum efficiency was 7.7%) that exceeds recently published values for this class of photocatalysts.

18.
ACS Appl Mater Interfaces ; 12(43): 48631-48641, 2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33064000

RESUMO

An efficient method for the deposition of ionic platinum species PtOx onto a TiO2 surface was developed on the basis of light-induced activation of the [Pt(NO3)6]2- anion. The deposited PtOx species with an effective Pt oxidation state between +4 and +2 have an oxygen-made environment and include single ion centers {PtOn} and polyatomic ensembles {PtnOm} connected to a TiO2 surface with Pt-O-Ti bonds. The resulting PtOx/TiO2 materials were tested as photocatalysts for the hydrogen evolution reaction (HER) from a water ethanol mixture and have shown uniquely high activity with the rate of H2 evolution achieving 11 mol h-1 per gram of Pt, which is the highest result for such materials reported to date. A combination of spectral methods shows that, under HER conditions, reduction of the supported PtOx species leads to the formation of well-dispersed nanoparticles of metallic platinum attached on the surface of TiO2 by Ti-O-Pt bonds. The high activity of the PtOx/TiO2 materials is believed to result from a combination of uniform distribution of small platinum nanoparticles over the titania surface and their close interaction with TiO2.

19.
Chemistry ; 26(57): 13085-13092, 2020 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-32640117

RESUMO

A nanoarchitectural approach based on in situ formation of quantum dots (QDs) within/outside clay nanotubes was developed. Efficient and stable photocatalysts active under visible light were achieved with ruthenium-doped cadmium sulfide QDs templated on the surface of azine-modified halloysite nanotubes. The catalytic activity was tested in the hydrogen evolution reaction in aqueous electrolyte solutions under visible light. Ru doping enhanced the photocatalytic activity of CdS QDs thanks to better light absorption and electron-hole pair separation due to formation of a metal/semiconductor heterojunction. The S/Cd ratio was the major factor for the formation of stable nanoparticles on the surface of the azine-modified clay. A quantum yield of 9.3 % was reached by using Ru/CdS/halloysite containing 5.2 wt % of Cd doped with 0.1 wt % of Ru and an S/Cd ratio of unity. In vivo and in vitro studies on the CdS/halloysite hybrid demonstrated the absence of toxic effects in eukaryotic cells and nematodes in short-term tests, and thus they are promising photosensitive materials for multiple applications.

20.
Dalton Trans ; 49(9): 2941-2946, 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32073071

RESUMO

The reduction of [(dpp-bian)BBr] (1, dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with dilithium naphthalenide in Et2O gives [{(dpp-bian)BBr}Li2(Et2O)2]2 (3). The treatment of [(dpp-bian)BONa] (5) and [(dpp-bian)Ge:] (7) with sodium is accompanied by protonation of the acenaphthylene fragment and affords [{(H-dpp-bian)BONa(dme)2}Na(dme)3] (6) and [(H-dpp-bian)Ge:][Na(dme)3] (8), respectively. Compounds 3, 6 and 8 have been characterized by 1H NMR and IR spectroscopy. The molecular structures of 3, [(dpp-bian)BOK] (4) and 8 have been established by single crystal X-ray analysis.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...