Activity In Medium Research Articles

Effects of deep eutectic solvents on the activity and stability of enzymes

From introduction of deep eutectic solvents (DESs) in 2003 and because of their unique properties such as low melting points, safety, low cost of raw material, availability, sustainability, and biodegradability, DESs are garnering attention in various fields of technology, particularly biocatalysis. Progress in these fields has illustrated that enzymes are able to maintain and even improve their activity and stability in DES-based media. Consequently, they became promising alternatives as developed solvents, cosolvents, or additives over conventional organic solvents. The current study reviewed the recent progress of the effects of various DESs on the function and stability of different enzymes.

Architecting FeNx on High Graphitization Carbon for High-Performance Oxygen Reduction by Regulating d-Band Center.

Fe single atoms and N co-doped carbon nanomaterials (Fe-N-C) are the most promising oxygen reduction reaction (ORR) catalysts to replace platinum group metals. However, high-activity Fe single-atom catalysts suffer from poor stability owing to the low graphitization degree. Here, an effective phase-transition strategy is reported to enhance the stability of Fe-N-C catalysts by inducing increased degree of graphitization and incorporation of Fe nanoparticles encapsulated by graphitic carbon layer without sacrificing activity. Remarkably, the resulted Fe@Fe-N-C catalysts achieved excellent ORR activity (E1/2 = 0.829V) and stability (19mV loss after 30K cycles) in acid media. Density functional theory (DFT) calculations agree with experimental phenomena that additional Fe nanoparticles not only favor to the activation of O2 by tailoring d-band center position but also inhibit the demetallization of Fe active center from FeN4 sites. This work provides a new insight into the rational design of highly efficient and durable Fe-N-C catalysts for ORR.

Social media as a means for students to become global citizens

The development of information technology, especially social media, has paved the way for the theory and concept of global citizenship. Integration and connection allow everyone to convey citizens' opinions, ideas, criticism, and actions. Based on the literature and previous studies, social media is analyzed in terms of benefits and disadvantages. This study aims to emphasize the use of social media among students, especially as a means of becoming global citizens. This research was conducted using qualitative methods by analyzing various literature and sources, which were then described. The study results a show that student activity in social media contributes to a new media ecology called global citizen solidarity in social media. Student solidarity in viewing various problems that occur led to civic action. Student actions on social media in various fields and issues on global issues such as politics, religion, economy, environment, health, philanthropy, and human rights reinforce the concept of being global citizens. The transformation regarding the use of social media by students into a theoretical framework for global citizen practice. It is important to re-describe the concept of global citizenship or cosmopolitanism through social media to create world citizen solidarity as a sense of responsibility in dealing with global problems and promoting world peace.

Istoriya regiona i strany v vuzovskih periodicheskih izdaniyah Donbassa 1970-h – nachala 2020-h gg.

From the beginning of the 20th century up to the present time Donbass has played an exceptionally important role in the history of the states of which it was a part. Such socio-cultural specificity of the region is reflected in its social life and, hence, in the activity of local mass media, including the university periodicals. Since the late Soviet period, the newspapers of Donbass higher educational institutions have closely intertwined their own corporate issues with the current socio-political agenda. A special media style of these publications was also formed. After 2014 university periodicals in Donbass became another tool for defending its sovereignty and fighting for reunification with Russia.

Solvothermal Engineering of NaTi2(PO4)3 Nanomorphology for Applications in Aqueous Na-Ion Batteries.

Aqueous Na-ion batteries are among the most discussed alternatives to the currently dominating Li-ion battery technology, in the area of stationary storage systems because of their sustainability, safety, stability, and environmental friendliness. The electrochemical properties such as ion insertion kinetics, practical capacity, cycling stability, or Coulombic efficiency are strongly dependent on the structure, morphology, and purity of an electrode material. The selection and optimization of materials synthesis route in many cases allows researchers to engineer materials with desired properties. In this work, we present a comprehensive study on size- and shape-controlled hydro(solvo)thermal synthesis of NaTi2(PO4)3 nanoparticles. The effects of different alcohol/water synthesis media on nanoparticle phase purity, morphology, and size distribution are analyzed. Water activity in the synthesis media of different alcohol solutions is identified as the key parameter governing the nanoparticle phase purity, size, and shape. The careful engineering of NaTi2(PO4)3 nanoparticle morphology allows control of the electrochemical performance and degradation of these materials as aqueous Na-ion battery electrodes.

Dual-Functional CuO-Decorated Bi3.84W0.16O6.24/Bi2WO6 Nanohybrids for Enhanced Electrochemical Hydrogen Evolution Reaction and Photocatalytic Cr(VI) Reduction Performance

The development of dual-functional nanohybrid-based electrocatalysts/photocatalysts for producing renewable energy and removing heavy metal pollutants describes an environmentally sustainable technique to address the challenges in energy and environment applications. Herein, we adopted microwave-assisted synthesis to develop CuO-decorated Bi3.84W0.16O6.24/Bi2WO6 (CuO/biphase-BW) dual-functional nanohybrids for electrochemical hydrogen evolution reaction (HER) and photocatalytic Cr(VI) reduction applications. CuO nanoparticles with ∼50 nm were uniformly distributed on an octahedron-shaped bismuth tungstate analyzed via a high-resolution transmission electron microscope technique. Biphase bismuth tungstate optimization was meticulously controlled via the amount of copper precursor added to the reaction. Among synthesized materials, CuO1.0/biphase-BW catalysts exhibit excellent HER activity in neutral media (0.5 M Na2SO4) with a relatively low overpotential of 111 mV at a current density of 10 mA/cm2, and also it exhibits a lower Tafel slope of 237 mV/dec. Moreover, CuO1.0/biphase-BW catalyst-coated carbon cloth exhibits good conductivity and excellent electrochemical stability for 24 h. Maximum photocatalytic reduction of aqueous Cr(VI) was achieved on the CuO1.0/biphase-BW catalyst. It is worth mentioning that the tremendous activity of the synthesized electrocatalyst/photocatalyst can be ascribed to the formation and electronic interaction of CuO with biphase Bi3.84W0.16O6.24/Bi2WO6, thus increasing its surface-active sites and charge transfer. Our work provides a facile and effective way to engineer dual-functional nanohybrids for efficient water splitting in a neutral medium and reducing toxic (Cr(VI)) metal.

Self-generated FeSe2 and CoSe2 nanoparticles confined in N, S-doped porous carbon as efficient and stable electrocatalyst for oxygen evolution reaction

Transition metal selenides embedded into a nitrogen, sulfur co-doped carbon materials (TMS@NSC) are promising electrocatalysts to effectively address the sluggish kinetics of oxygen evolution reaction (OER). However, the OER catalytic activity of single metal TMS@NSC is still limited by insufficient active sites. Hence, FeSe2 and CoSe2 nanoparticles self-generated and confined in N, S-doped porous carbon (FeSe2/CoSe2@NSC) catalyst has been synthesized by in-situ polymerization and the subsequent low temperature selenization strategy, aiming to increase the active sites of TMS@NSC. The hybridized FeSe2/CoSe2@NSC catalyst has excellent OER catalytic activity and good durability in alkaline media, which only requiring an overpotential as low as 278 mV to drive a current density of 10 mA cm−2, outperforming most recently reported selenide catalysts and commercial RuO2 catalysts. The high catalytic activity of FeSe2/CoSe2@NSC catalyst is attributed to the rapid electron transfer between FeSe2 and CoSe2 in the unique N, S-doped graphene nanosheets, which effectively inhibits the aggregation of nanoparticles, fully exposes the active sites and provides pathway for oxygen release during the OER process. Moreover, the overall water splitting device assembled with FeSe2/CoSe2@NSC catalyst showed low overpotential of 1.57 V. This study provides a feasible strategy for the design of high active and stable TMS@NSC catalysts for OER and other energy conversion applications.

Transforming Cross-Linked Cyclic Dimers of KR-12 into Stable and Potent Antimicrobial Drug Leads.

Is it possible to enhance structural stability and biological activity of KR-12, a truncated antimicrobial peptide derived from the human host defense peptide LL-37? Based on the mapping of essential residues in KR-12, we have designed backbone-cyclized dimers, cross-linked via a disulfide bond to improve peptide stability, while at the same time improving on-target activity. Circular dichroism showed that each of the dimers adopts a primarily alpha-helical conformation (55% helical content) when bound to lyso-phosphatidylglycerol micelles, indicating that the helical propensity of the parent peptide is maintained in the new cross-linked cyclic form. Compared to KR-12, one of the cross-linked dimers showed 16-fold more potent antimicrobial activity against human pathogens Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans and 8-fold increased activity against Escherichia coli. Furthermore, these peptides retained antimicrobial activity at physiologically relevant conditions, including in the presence of salts and in human serum, and with selective Gram-negative antibacterial activity in rich growth media. In addition to giving further insight into the structure-activity relationship of KR-12, the current work demonstrates that by combining peptide stabilization strategies (dimerization, backbone cyclization, and cross-linking via a disulfide bond), KR-12 can be engineered into a potent antimicrobial peptide drug lead with potential utility in a therapeutic context.

Engineering the interface of porous CoMoO3 nanosheets with Co3Mo nanoparticles for high-performance electrochemical overall water splitting

• Interfacial Co 3 Mo nanoparticles/porous CoMoO 3 nanosheets heterostructures (Co 3 Mo/CoMoO 3 NPSs) grown on nickel foam were successfully fabricated via a simple hydrothermal reaction and subsequent annealing process under controlled atmospheres. • The fabricated Co 3 Mo/CoMoO 3 NPSs exhibit excellent activity and stability for hydrogen evolution reaction (HER) and overall water splitting performance. • The main origins are the interface engineering of Co 3 Mo/CoMoO 3 heterostructure, the unique interfacial electronic structure and increased electrochemical active areas, which remarkably endow Co 3 Mo/CoMoO 3 NPSs with impressive catalytic performance. • Density functional theory calculations illustrate electron transfer from Co 3 Mo to CoMoO 3 at the interfaces, where electron accumulation on CoMoO 3 favors the dissociation of H 2 O molecule, electron-deficient Co atoms in Co 3 Mo have optimized H* absorption energy, Co 3 Mo and CoMoO 3 cooperate synergistically to promoting HER activity in alkaline media. The design of high-performance electrocatalysts for alkaline water splitting is of significant importance for the development of a sustainable hydrogen economy. Herein, heterostructured Co 3 Mo nanoparticles/porous CoMoO 3 nanosheets (Co 3 Mo/CoMoO 3 NPSs) were constructed for alkaline water splitting by annealing CoMoO x nanosheets under controlled atmospheres. Thanks to its interfacial electronic structure and increased electrochemical active area, Co 3 Mo/CoMoO 3 NPSs exhibit impressive hydrogen evolution reaction (HER) activity with an overpotential of 334 mV at 1000 mA cm -2 and a Tafel slope of 46.4 mV per decade in 1.0 M KOH, which outperforms Pt/C catalyst (621 mV and 74.7 mV per decade). Density functional theory calculations illustrate the electron transfer from Co 3 Mo to CoMoO 3 at the interfaces, where electron accumulation on CoMoO 3 favors the dissociation of H 2 O molecule, and electron-deficient Co atoms in Co 3 Mo have optimized H* absorption energy for HER. The Co 3 Mo/CoMoO 3 NPSs also exhibit higher oxygen evolution reaction activity than the RuO 2 catalyst. Moreover, the water electrolyzer using Co 3 Mo/CoMoO 3 NPSs as both cathode and anode only requires 1.59 V to deliver a current density of 100 mA cm -2 in 1.0 M KOH, which outperforms benchmark Pt/C RuO 2 electrodes couple with 1.69 V to reach the same current density, providing great potential for large-scale applications.

Artemisia afra and Artemisia annua Extracts Have Bactericidal Activity against Mycobacterium tuberculosis in Physiologically Relevant Carbon Sources and Hypoxia.

Mycobacterium tuberculosis (Mtb) is a deadly pathogen and causative agent of human tuberculosis, causing ~1.5 million deaths every year. The increasing drug resistance of this pathogen necessitates novel and improved treatment strategies. A crucial aspect of the host-pathogen interaction is bacterial nutrition. In this study, Artemisia annua and Artemisia afra dichloromethane extracts were tested for bactericidal activity against Mtb strain mc26230 under hypoxia and various infection-associated carbon sources (glycerol, glucose, and cholesterol). Both extracts showed significant bactericidal activity against Mtb, regardless of carbon source. Based on killing curves, A. afra showed the most consistent bactericidal activity against Mtb for all tested carbon sources, whereas A. annua showed the highest bactericidal activity in 7H9 minimal media with glycerol. Both extracts retained their bactericidal activity against Mtb under hypoxic conditions. Further investigations are required to determine the mechanism of action of these extracts and identify their active constituent compounds.

The synthesis of iron-nitrogen sites embedded in electrospun carbon nanofibers with an excellent oxygen reduction reaction activity in alkaline/acidic media

Metal-nitrogen carbon catalysts have received great attention in the field of gas-evolving electrocatalysis due to their high activity, large specific surface area and efficient gas diffusion paths. A solution of porphyrin iron, g-C3N4 and polyacrylonitrile in N,N-dimethylformamide was sonicated and electrospun into doped polyacrylonitrile nanofibers (NFs), and the NFs were then stabilized and carbonized at 900 °C to prepare Fe-N/CNF catalyst for oxygen reduction reaction (ORR). It was found that the addition of g-C3N4 to the electrospinning precursor led to the formation of abundant Fe-N species in Fe3+ and Fe2+ valence states, while Fe3C nanoparticles were formed without adding g-C3N4. Compared to Fe3C/CNF prepared without g-C3N4, the Fe-N/CNF catalyst presents an 4e− improved oxygen reduction reaction activity in both alkaline and acidic media. Furthermore, as a cathode in Zn-air batteries, the Fe-N/CNF catalyst exhibits high performance with an open-circuit voltage of 1.49 V, a power density of 146 mW cm−2 and a specific capacity of 703 mAh g-1. This work suggests a way to prepare metal-nitrogen-carbon catalysts for energy-related electrocatalytic applications.

Collective directional migration drives the formation of heteroclonal cancer cell clusters.

Metastasisation occurs through the acquisition of invasive and survival capabilities that allow tumour cells to colonise distant sites. While the role of multicellular aggregates in cancer dissemination is acknowledged, the mechanisms that drive the formation of multiclonal cell aggregates are not fully elucidated. Here, we show that cancer cells of different tissue of origins can perform collective directional migration and can actively form heteroclonal aggregates in 3D, through a proliferation-independent mechanism. Coalescence of distant cell clusters is mediated by subcellular actin-rich protrusions and multicellular outgrowths that extend towards neighbouring aggregates. Coherently, perturbation of cytoskeletal dynamics impairs collective migration while myosin II activation is necessary for multicellular movements. We put forward the hypothesis that cluster attraction is mediated by secreted soluble factors. Such a hypothesis is consistent with the abrogation of aggregation by inhibition of PI3K/AKT/mTOR and MEK/ERK, the chemoattracting activity of conditioned culture media and with a wide screening of secreted proteins. Our results present a novel collective migration model and shed light on the mechanisms of formation of heteroclonal aggregates in cancer.

Adolescents’ Digital activity and its Correlation with Cognitive-Emotional Features, School Performance, and Social and Age Factors: Cross-Sectional Study

Background. The study of digital activity correlation with cognitive-emotional features, as well as with other parameters of adolescents’ life-activity in non-capital regions of Russian Federation remains relevant.Objective. The aim of the study is to analyze the digital activity structure in adolescents and its correlation with cognitive-emotional features, school performance and social and age factors.Methods. Participants are secondary school students of the 8th–11th grades. Digital activity was examined via online survey among adolescents. We took into account the use of social media, information search, watching videos on the Internet, using of messengers, playing games with electronic devices. Cognitive features (memory, thinking, executive functions, sensory information procession, reading and speech, understanding of emotions, decision-making) and emotional state of adolescents (anxiety) were evaluated by clinical psychologists via various tests. School performance was determined by the recent results of the school quarters/semester finished by the time of the survey. Social and age factors included regular out-of-school physical activity and family structure (complete/ incomplete).Results. We have examined 438 teenagers. 53 (12%) respondents spend more than 5 hours a day with digital devices on weekdays, 133 (30%) — on weekends, 147 (34%) — during the holidays. Structure of digital activity during weekdays (≥ 1 hour) among adolescents was the following: activity in social media prevailed (63.5% of respondents), fewer teenagers searched for information or watched videos on the Internet (47.3 and 42.9%, respectively), about a third (34.9%) played via electronic devices. Structure of digital activity changed over the weekend and during the holidays. We have revealed differences between the information search activity and the volume of short-time memory, understanding the verbal messages, and verbal-logical operations level. Adolescents with different levels of computer gaming activity have shown diversity in sensomotor reaction speed, visuospatial memorization accuracy, number of errors in high-speed reading, reading pace, and understanding text basic meaning.Conclusion. The greater time of digital activity among 8th–11th grades students is associated with negative results of cognitive activity and school performance.

Integrating RuCo alloy in N-doped carbon nanofiber for efficient hydrogen evolution in alkaline media

Ruthenium (Ru) is considered as a promising element for constructing alkaline hydrogen evolution (HER) catalysts due to its rapid water dissociation kinetics and low-cost advantages than Pt. Alloying can optimize the electrochemical performance of metals and reduce the usage of the noble metal. Herin, RuCo alloy nanoparticles were grown in-situ on N-doped carbon nanofibers (RuCo/NCNF) by electrospinning and graphitization. Under thermodynamic driving force, the Ru and Co elements formed RuCo alloys. It is worth noting that the Ru not only improved the catalytic performance, but also reduced the nanoparticle size and exposing more active sites. Moreover, N-doped carbon nanofiber was not only used to load RuCo alloy nanoparticle, but also as a good substrate for the HER reaction. Therefore, the RuCo/NCNF had fabulous catalytic activity in alkaline media. Furthermore, the in-situ growth also endowed the RuCo/NCNF with excellent stability, HER performance was not significantly reduced even after 40 h stability test. And when the Ru:Co = 1:8, RuCo/NCNF had the excellent HER catalytic performance. Only 41 mV was required to drive a current density of 10 mA cm−2, with Tafel Slope as low as 64.8 mV dec−1.

Analysis of individual characteristics influencing user polarization in COVID-19 vaccine hesitancy.

During the COVID-19 pandemic, vaccine hesitancy proved to be a major obstacle in efforts to control and mitigate the negative consequences of COVID-19. This study centered on the degree of polarization on social media about vaccine use and contributing factors to vaccine hesitancy among social media users. Examining the discussion about COVID-19 vaccine on the Weibo platform, a relatively comprehensive system of user features was constructed based on psychological theories and models such as the curiosity-drive theory and the big five model of personality. Then machine learning methods were used to explore the paramount impacting factors that led users into polarization. Findings revealed that factors reflecting the activity and effectiveness of social media use promoted user polarization. In contrast, features reflecting users' information processing ability and personal qualities had a negative impact on polarization. This study hopes to help healthcare organizations and governments understand and curb social media polarization around vaccine development in the face of future surges of pandemics.

Triple Interface Optimization of Ru‐based Electrocatalyst with Enhanced Activity and Stability for Hydrogen Evolution Reaction

AbstractA challenging task is to promote Ru atom economy and simultaneously alleviate Ru dissolution during the hydrogen evolution reaction (HER) process. Herein, Ru nanograins (≈1.7 nm in size) uniformly grown on 1T‐MoS2 lace‐decorated Ti3C2Tx MXene sheets (Ru@1T‐MoS2‐MXene) are successfully synthesized with three types of interfaces (Ru/MoS2, Ru/MXene, and MoS2/MXene). It gives high mass activity of 0.79 mA µgRu−1 at an overpotential of 100 mV, which is ≈36 times that of Ru NPs. It also has a much smaller Ru dissolution rate (9 ng h−1), accounting for 22% of the rate for Ru NPs. Electrochemical tests, scanning electrochemical microscopy measurements combined with DFT calculations disclose the role of triple interface optimization in improved activity and stability. First, 2D MoS2 and MXene can well disperse and stabilize Ru grains, giving larger electrochemical active area. Then, Ru/MoS2 interfaces weakening H* adsorption energy and Ru/MXene interfaces enhancing electrical conductivity, can efficiently improve the activity. Next, MoS2/MXene interfaces can protect MXene sheet edges from oxidation and keep 1T‐MoS2 phase stability during the long‐term catalytic process. Meanwhile, Ru@1T‐MoS2‐MXene also displays superior activity and stability in neutral and alkaline media. This work provides a multiple‐interface optimization route to develop high‐efficiency and durable pH‐universal Ru‐based HER electrocatalysts.

Photoreactive Mercury-Containing Metallosupramolecular Nanoparticles with Tailorable Properties That Promote Enhanced Cellular Uptake for Effective Cancer Chemotherapy.

A new potential route to enhance the efficiency of supramolecular polymers for cancer chemotherapy was successfully demonstrated by employing a photosensitive metallosupramolecular polymer (Hg-BU-PPG) containing an oligomeric poly(propylene glycol) backbone and highly sensitive pH-responsive uracil-mercury-uracil (U-Hg-U) bridges. This route holds great promise as a multifunctional bioactive nano-object for development of more efficient and safer cancer chemotherapy. Owing to the formation of uracil photodimers induced by ultraviolet irradiation, Hg-BU-PPG can form a photo-cross-linked structure and spontaneously forms spherical nanoparticles in aqueous solution. The irradiated nanoparticles possess many unique characteristics, such as unique fluorescence behavior, highly sensitive pH-responsiveness, and intriguing phase transition behavior in aqueous solution as well as high structural stability and antihemolytic activity in biological media. More importantly, a series of cellular studies clearly confirmed that the U-Hg-U photo-cross-links in the irradiated nanoparticles substantially enhance their selective cellular uptake by cancer cells via macropinocytosis and the mercury-loaded nanoparticles subsequently induce higher levels of cytotoxicity in cancer cells (compared to non-irradiated nanoparticles), without harming normal cells. These results are mainly attributed to cancer cell microenvironment-triggered release of mercury ions from disassembled nanoparticles, which rapidly induce massive levels of apoptosis in cancer cells. Overall, the pH-sensitive U-Hg-U photo-cross-links within this newly discovered supramolecular system are an indispensable factor that offers a potential path to remarkably enhance the selective therapeutic effects of functional nanoparticles toward cancer cells.

A Mild, Efficient and Sustainable Tetrahydropyranylation of Alcohols Promoted by Acidic Natural Deep Eutectic Solvents.

A straightforward protocol to promote the tetrahydropyranylation of alcohols, using for the first time bioinspired acidic natural deep eutectic solvents (NADESs) as non-innocent reaction media under mild reaction conditions, was reported. This approach enables the preparation of several tetrahydropyranyl (THP) ethers starting from primary, secondary and tertiary alcohols in short reaction times and with high levels of chemoselectivity, working under air and without the need of additional catalyst. The sustainability of the methodology was further highlighted by its scalability and the easy recyclability of the NADES, allowing multigram preparations of THP ethers without any loss of the catalytic activity of the reaction media up to ten recycling steps. Telescoped, one-pot tetrahydropyranylation/nucleophilic acyl substitution transformations using the same eutectic mixture were also demonstrated.

Assessment of bioactive components of essential oils for antimicrobial activity in the dairy food matrix

Essential oils as a whole have been widely investigated for their antimicrobial properties against spoilage microorganisms and pathogens. However limited information is available about the inhibitory activities of components of EO in foods and more specifically in dairy food matrices. The widespread components of common EOs were evaluated for their antibacterial activity in media and skim milk. Amongst the EO components, trans-cinnamaldehyde and eugenol were the most effective on the basis of disk assay and minimum bactericidal concentrations in milk. The MBC of these EOs was unaffected by the conditions of the incubation temperature of milk. However the MBC was decreased in paneer slurry against L.monocytogenes and E. coli O157:H7 when incubated at 7 °C than37 °C. In the dairy spread, trans-cinnamaldehyde and eugenol were effective in inhibiting TBC, coliform, and yeast & mold count at 0.26 mg/g without affecting sensory properties. The microbial load in paneer made from EO added to milk (10 mg/ml) significantly inhibited microbial growth during storage. In addition eugenol has shown antioxidant activity in milk through ABTS radical scavenging assay.

Ultrafine iridium nanoparticles prepared without a surfactant for the acidic oxygen evolution reaction

Ultrafine metal Ir nanoparticles prepared by a surfactant-free synthesis method exhibit excellent OER activity in acidic media, with a low overpotential of 299 mV at 10 mA cm−2 and a high mass activity of 132 A gIr−1 at 1.53 V vs. RHE.