Formation Of Products Research Articles

Corrosion Inspection for Hard Disk Media with Carbon-Based Overcoats by In-Liquid Open-Loop Electric Potential Microscopy.

The hard disk medium (HDM) with a carbon overcoat (COC) is a fundamental component of a hard disk drive. The conventional test for its corrosion durability, known as the "HOT/WET test," requires considerable time and effort and does not provide any local information about the corrosion. Here, we address this issue by employing open-loop electric potential microscopy (OL-EPM), a potential measurement technique based on atomic force microscopy (AFM), for corrosion inspection. To explore the applicability of OL-EPM, we observed the surface of the HDMs with different COC thicknesses in a dilute HNO3 solution. Through time-dependent and high-resolution OL-EPM observations, we found that this technique can be used for detecting nanoscale COC defects. This is because the HDM surface under a COC defect is exposed to the solution and undergoes anodic dissolution, increasing the local potential around the defect. This is readily detected by OL-EPM even before corrosion product formation around the defects induces the topographic change. This work demonstrates that OL-EPM is useful not only for understanding the local corrosion mechanisms but also for detecting the COC defects in a much shorter time (∼3 h) than the HOT/WET test (3-4 days).

B(C6F5)3 Catalyzed Regiodivergent Thioetherifications of Alkenes via Thiiranium Intermediates: Experimental and Computational Insights.

Precise control of selective alkene functionalization is a continuing challenge in the chemical community. In this study, we develop a substitution-controlled regiodivergent thioetherification of di- or trisubstituted alkenes using 10 mol% tris(pentafluorophenyl)borane [B(C6F5)3] as a catalyst and N-thiosuccinimide as a sulfenylating reagent. This metal-free borane catalyzed C-S bond forming method is utilized for a Csp2-H sulfenylation reaction to synthesize an array of diphenylvinylsulfide derivatives with good to excellent yields (25 examples, up to 91% yield). Some of the products exhibit aggregation-induced emission luminogen properties used in organic light-emitting diodes (OLEDs), chemical sensors, and biological imaging units. Depending upon the starting alkene, Csp3-S sulfenylation products could also be generated regioselectively. A variety of allylic thioethers from α-alkyl substituted styrenes were isolable in good yields and selectivities (14 examples, up to 67% yield). The DFT-supported mechanistic study confirms that the reaction proceeds via a thiiranium ion intermediate, where the regioselectivity and product formation are determined by the alkene substituents which influences the activation barriers and energy profiles. Diphenylvinylsulfide derivatives can also be efficiently transformed into a range of synthetically valuable compounds, including vinyl sulfoxides, vinyl sulfones, and vinyl sulfoximines.

Determination of isoniazid by photometric method through covalent binding with carbocyanine dye

Substitution reactions in carbocyanine dyes are used to determine nucleophilic compounds. The interaction of a chlorine-containing carbocyanine with a number of medicinal substances has been studied. It was shown that in the reaction with isoniazid in the presence of surfactants, this dye selectively changes color from yellow-green to purple. Chromatography-mass spectrometry has proven the formation of the substitution product of chlorine with isoniazid. The reaction occurs within 20 minutes in the presence of 1 mM cetyltrimethylammonium bromide. The detection limit of isoniazid in water by photometric method was 10 µg/mL; in diluted artificial urine using fluorimetry, it was 0.3 µg/mL. The method does not require full-spectrum equipment, which simplifies the determination.

Reaction Pathway Regulation for Gaseous and Liquid Products of Electrocatalytic CO2 Reduction under Adsorbate Interactions

Halide anion adsorption on transition metals can improve the performance of electrochemical CO2 reduction reaction (CO2RR), while the specific reaction mechanisms governing selective CO2RR pathways remain unclear. In this study, we demonstrate for the first time the distinct pathways for gaseous (CO) and liquid products (formate and ethanol) on the well‐defined Ag‐Cu nanostructures with controlled chlorination, respectively. We show that CO2 conversion to CO on Ag/AgCl can be tuned by adjusting the thickness of AgCl layer, achieving a Faradaic efficiency (FE) near 100% over a broad potential range in a 0.5 M KHCO3 using flow cell. In contrast, the optimized Cl‐Ag/Cu system enables the conversion of CO2 into liquid products including formate and ethanol with a total FE nearing 100%, delivering high current density under similar conditions. In situ infrared experiments and theoretical calculations reveal that the lateral adsorbate of *OCHO intermediate facilitates the thermodynamics of both the CO pathway on Cl‐Ag(111) and the formate pathway on Cl‐Ag/Cu(111) by reducing Gibbs free energy barriers of each potential‐limit step. This work uncovers the role of chlorination in the tuning of C‐bound or O‐bound intermediates during CO2RR on Ag‐Cu catalysts, determining the reaction pathway under lateral adsorbate effects.

Evaluation of the Participation of Brazilian Women in Research in Oral Pathology and Oral Medicine.

Despite recent advancements, women still encounter significant challenges in various fields, including dentistry. However, the increasing interest in female participation in science acknowledges its fundamental role in the advancement of knowledge. This study aims to assess indicators of women's involvement in Brazilian research in the areas of Oral Pathology and Oral Medicine. This cross-sectional study evaluated 197 professionals affiliated with the Brazilian Society of Stomatology and Oral Pathology in 2023. Data were collected from publicly available Lattes curriculum and organized into three sets of information: researcher profile, scientific production and human resources formation. Both the data from the researcher's entire career and from the last 5 years (2019-2023) were assessed separately. Descriptive analyses of categorical variables were performed, while the Mann-Whitney test was employed to compare the numerical variables regarding researchers' gender. Of 197 professionals, 117 (59.4%) were female. Although there was no significant difference in scientific production between genders, men had more publications, received approximately twice as many citations, and exhibited higher H-index values compared to women. Notably, women surpassed men in undergraduate student supervision, while men predominated in supervising master's and PhD students. This study highlighted the relevance of female participation in Oral Pathology and Oral Medicine research in Brazil. However, disparities persist regarding women participation, especially in scientific article citations and postgraduate students' supervision.

Reaction Pathway Regulation for Gaseous and Liquid Products of Electrocatalytic CO2 Reduction under Adsorbate Interactions.

Halide anion adsorption on transition metals can improve the performance of electrochemical CO2 reduction reaction (CO2RR), while the specific reaction mechanisms governing selective CO2RR pathways remain unclear. In this study, we demonstrate for the first time the distinct pathways for gaseous (CO) and liquid products (formate and ethanol) on the well-defined Ag-Cu nanostructures with controlled chlorination, respectively. We show that CO2 conversion to CO on Ag/AgCl can be tuned by adjusting the thickness of AgCl layer, achieving a Faradaic efficiency (FE) near 100% over a broad potential range in a 0.5 M KHCO3 using flow cell. In contrast, the optimized Cl-Ag/Cu system enables the conversion of CO2 into liquid products including formate and ethanol with a total FE nearing 100%, delivering high current density under similar conditions. In situ infrared experiments and theoretical calculations reveal that the lateral adsorbate of *OCHO intermediate facilitates the thermodynamics of both the CO pathway on Cl-Ag(111) and the formate pathway on Cl-Ag/Cu(111) by reducing Gibbs free energy barriers of each potential-limit step. This work uncovers the role of chlorination in the tuning of C-bound or O-bound intermediates during CO2RR on Ag-Cu catalysts, determining the reaction pathway under lateral adsorbate effects.

Physiological Features of Yield Formation of Sunflower Breeding Samples in Arid Conditions of the Ukrainian Steppe

The research methodology was based on determining the soil moisture consumption per unit of photosynthesis productivity, establishing the influence of the moisture consumption coefficient on the productivity of photosynthesis on the yield of sunflower genotypes. The aim of the research was to determine the physiological characteristics of the formation of plant productivity of different sunflower samples and use them in assessing and creating genotypes for cultivation in arid conditions. The conducted investigations allowed to determine physiological factors and properties of plants that determine the level of formation of the weight of seeds of the head and the yield of sunflower. The weight of seeds of the head is determined by the amount of soil moisture consumption per unit of net productivity. Between the indicators of soil moisture consumption per unit of net productivity at the stage of formation of the head - the beginning of flowering, a direct negative correlation interdependence was established. Sunflower varieties with a minimum consumption of soil moisture per unit of net productivity of photosynthesis of 1.01-1.05 m-3 g m-2 per day form in arid conditions of the Steppe of Ukraine the maximum level of weight of seeds of the head of 58.7-78.7 g, which ensures obtaining a high yield within 2.68-3.49 t ha-1. The conducted assessment of genotypes by indicators of soil moisture consumption per unit of net productivity made it possible to create highly productive varieties of sunflower Emelard, Igolya, Orlik.

Carbonylation and Other Transformations of Polyfluorobenzocyclobutenols in Super Acids

Acid-catalyzed carbonylation of a number of polyfluorinated benzocyclobuten-1-ols, as well as cyclic sulfoesters of benzocyclobuten-1,2-diols, in reaction with carbon monoxide has been carried out. The efficiency of using TfOH and FSO3H-SbF5 as acidic systems was evaluated. Both products of CO addition with the remaining four-membered ring — the corresponding carboxylic acids, and various products of carbonylation accompanied by its transformations (ring opening, opening followed by heterocyclization with the formation of isochromane derivatives, expansion to a five-membered one) were obtained. In some cases, the formation of polycyclic dimeric products was also observed.

Influence of metakaolin on physical and mechanical properties of cement stone heat-resistant binder from mineral-technogenic raw materials of the Aral region

The results of studies of the influence of metakaolin obtained from kaolin of the Khodzhakul deposit on the process of formation of cement stone based on heat-resistant binder from mineral-technogenic raw materials of the Aral Sea region are presented. It has been established that metakaolin allows one to control the processes of hydration, setting and hardening of the cement mass. The high degree of hydration of aluminous cement in the presence of metakaolin provides porosity and sufficiently high compressive strength of the cement stone in the last 14‒28 days of hardening. Increasing the concentration of metakaolin in the cement mixture to 15 % affects not only the process of liquefying the cement mortar, reducing the setting and hardening time of the cement mass, but also increases the compressive strength of the cement stone. New formations of hydration products have been studied.

Tuning Strategies of Indium‐Based Catalysts for Electrocatalytic Carbon Dioxide Reduction

In electrocatalytic carbon dioxide reduction (CO2RR), indium (In)‐based catalysts with low toxicity and environmental benefits are renowned for their specific high selectivity for formic acid and intrinsic inertia for the competing hydrogen evolution reaction. However, recent studies have reported various products over In‐based catalysts showing comparable or even higher selectivity for carbon monoxide (CO) than for formic acid (HCOOH), puzzling the reaction pathway for CO2 reduction. This article presents a comprehensive review of recent studies on electrocatalytic CO2RR over In‐based catalysts highlighting the formation pathway of specific products. First, the mechanism of electrocatalytic CO2RR with the multiple reaction pathways is concluded considering the relationship between reaction intermediates and selectivity. Furthermore, the regulation strategies for multiple product formation are summarized, including crystalline phase engineering, alloying, nanostructuring, and structural modulation of In single atom, where the effect of key intermediates (*COOH, *OOCH, and *OCHO) on product generation is systematically discussed to achieve high selectivity. Finally, the intrinsic regulation mechanisms of these strategies are analyzed and the challenges and opportunities for the development of next‐generation In‐based catalysts are proposed.

Silver‐Based Supportless Membrane Electrode Assemblies for Electrochemical CO2 Reduction

ABSTRACTMost commonly, electrochemical CO2 reduction is performed in a three‐compartment setup employing gas diffusion electrodes (GDEs) to decrease mass transport limitations of the gaseous reactant CO2 to the reaction interface. However recently, there has been a rising number of investigations on suitable membrane electrode assemblies (MEAs) to overcome ohmic potential losses caused by the electrolyte gaps in the systems. While the significant majority of MEAs exhibited in literature is based on catalyst‐coated gas diffusion layers, this work presents an approach that does not require a likewise support. On the basis of a catalyst suspension similar to mixtures already employed for GDE production on industrial level, a method to directly transfer the resulting catalyst layers to the membrane is developed. The Faradaic efficiency of carbon monoxide, i.e. target product formation of GDEs manufactured according to a similar procedure, can be matched or even exceeded for individual modifications of the exchange MEAs. Simultaneously, the cell potentials can be remarkably decreased in this setup. By gradual adaptation of the fabrication procedure, the influence of important manufacturing parameters is unraveled, also discussing the effect of hydrogen permeation through the membrane.

Interplay between Energy and Entropy Mediates Ambimodal Selectivity of Cycloadditions.

One ambimodal transition state can lead to the formation of multiple products. However, it remains fundamentally unknown how the energy and entropy along the post-TS pathways mediate ambimodal selectivity. Here, we investigated the energy and entropy profiles along the post-TS pathways in four [4 + 2]/[6 + 4] cycloadditions. We observe that the pathway leading to the minor product involves a more pronounced entropic trap. These entropic traps, resulting from the conformational change in the dynamic course of ring closure, act as a reservoir of longer-lived dynamic intermediates that roam on the potential energy surface and have a higher likelihood of redistributing to form the other product. The SpnF-catalyzed Diels-Alder reaction produces [4 + 2] and [6 + 4] adducts with nearly equal product distribution and relatively flat energy profiles, in contrast to other cycloadditions. Unexpectedly, the entropy profiles for these two adducts are distinctly different. The formation of the [6 + 4] adduct encounters an entropic barrier acting as a dynamical bottleneck, while the [4 + 2] adduct involves a substantial entropic trap to maintain long-lived intermediates. These opposing effects hinder both product formations and likely cancel each other out so that an equal product distribution is observed.

Theoretical Insight into the Multiple Roles of the Silyl-Phenanthroline Ligand in Ir-Catalyzed C(sp3)-H Borylation.

Silyl-phenanthroline (NN'Si) ligand ancillary iridium-catalyzed C(sp3)-H borylation is investigated theoretically. Density functional theory calculations clearly disclose that the (NN'Si)IrV(H)(Bpin)3 (NN'Si = 6-[(di-tert-butylsilyl)methyl]-1,10-phenanthroline) complex is a resting state, and the (NN'Si)IrIII(Bpin)2 complex serves as an active species in the catalytic cycle. The remarkably high activity of this type of a catalyst arises from the rapid reductive elimination of HBpin from (NN'Si)IrV(H)(Bpin)3 to generate the active species (NN'Si)IrIII(Bpin)2. The silyl group plays a crucial role in accelerating the crucial hydride-migration elementary step, which allows the isomerization of the (NN'Si)IrV(R)(H)(Bpin)2 intermediate to achieve the C(sp3)-B reductive elimination and afford the borylated product. Although C(sp3)-H borylation with HBpin is thermodynamically unfavorable, the Ir-dihydride intermediate (NN'Si)IrV(H)2(Bpin)2 generated after product formation is slightly more stable than resting-state (NN'Si)IrV(H)(Bpin)3 in this catalytic cycle, which is an important driving force for the HBpin reaction. Such success was not attained by many other traditional bidentate ligands. The unique regioselectivity of n-butyl ethyl ether and 2-methylheptane, induced by the NN'Si-pincer ligand, is well reproduced and the underlying reason for the selectivity is clearly elucidated.

Guidance on surface cyclization reactions through coordination structures.

Metal coordination structures, formed through interactions between metal atoms and active functional groups, are crucial in determining the reaction pathway and its products. This study examines 2,3-dibromo-6,7-dicyanonaphthalene (DDN), which contains cyano and halogen groups, deposited on Au(111) and Ag(111) surfaces, using scanning tunneling microscopy at room temperature. The reason for the formation of various cyclization products on the Au(111) surface is that the bromine of DDN and the cyano group have overlapping reaction temperature ranges. This overlap leads to the coexistence of C-C coupling products from the debromination sites and cyclization products from the cyano groups. In contrast, on the Ag(111) surface, the final cyclization reaction produces a single type of polymer directly induced by the metal-coordinated structures. The synergistic effects between coordination structures and the activation temperatures of molecular reaction groups are crucial factors in regulating polymerization reactions.

Computational Insights into the Effect of Ligands and Transition-Metal Centers on the Mechanism and Regioselectivity of Hydrosilylation of Alkenes.

Development of sustainable synthetic methods for the hydrosilylation of alkenes, catalyzed by 3d transition metals, offers a promising alternative to traditional noble metal catalysts. This study presents a computational mechanistic investigation into the hydrosilylation of alkenes, focusing on the role of ligands and metal centers in modulating the reaction's mechanism and regioselectivity. The ligand's electronic and steric properties were found to modulate the regioselectivity for cobalt catalysts, with phosphine ligand (xantphos) promoting higher linear selectivity compared to nitrogen-based ligand (mesPDI). The energy decomposition analysis reveals that the xantphos ligand favors linear products due to stronger electrostatic and orbital interactions despite increased steric repulsion. The metal center also plays a crucial role, with cobalt catalysts favoring the modified Chalk-Harrod mechanism for branched product formation in the presence of PNN ligand (iPrPCNNMe), due to lower activation barriers in alkene insertion. Beneficial electrostatic and orbital interactions predominate, rendering the alkene insertion transition state for cobalt more favorable compared to that for iron. This work provides a comprehensive understanding of how ligand and metal center effects can be harnessed to control regioselectivity in hydrosilylation reactions.

Catalytic Ozonation of Formaldehyde with an Oxygen-Vacancy-Rich MnOx/γ-Al2O3 Catalyst at Room Temperature

Formaldehyde (HCHO) is known as one of the important indoor organic pollutants. How to remove and decompose the low concentration of formaldehyde at room temperature is important for indoor environments. Catalytic ozonation is an efficient method to thoroughly remove HCHO at room temperature, with high efficiency and few byproducts. A series of MnOx/γ-Al2O3 catalysts were prepared in this work via the impregnation method and treated with different reagents (acid, alkali, and H2O2) to evaluate their catalytic activity for HCHO removal. The results showed that MnAl-II (acid treatment) performed well in activity tests, reaching a nearly 100% HCHO conversion at an O3/HCHO of 2.0 and attaining a CO2 selectivity of above 95% at an O3/HCHO of 3.0 at 30 °C, with almost no ozone residual existing. The larger specific surface area, abundant oxygen vacancies, and higher number of acid sites contributed to the excellent performance of MnAl-II. Stability and H2O resistance tests of MnAl-II were also conducted. To reveal the intermediate product formation and further investigate the reaction mechanism of HCHO ozonation, in-situ DRIFTS measurement was carried out combined with DFT calculations.

Removal of TBP sorbed on wood by Trametes versicolor through solid-state fermentation

The use of white-rot fungi is a promising approach for removing organophosphate flame retardants (OPFRs) from wastewaters. Immobilization in wood for this purpose ensures the predominance of the fungus but also contributes to OPFRs sorption. This work focused on the ability of T. versicolor to degrade tributyl phosphate (TBP) sorbed in wood. This initially underwent ten sorption cycles, each involving exposure to a 10mg · L-1 TBP solution. Throughout each cycle, the wood exhibited a sustained sorption capacity (0.035 ± 0.002mg TBP · g. dry wood-1 per cycle). The wood residues obtained after each sorption cycle were inoculated with T. versicolor. After 60 days of inoculation, fungus degraded over 90% of TBP in each cycle’s wood residue. However, fungal growth was inhibited, resulting in a 43% decrease in biomass compared to controls. The fact that biomass remained active and capable of degrading TBP suggests that the growth decrease is likely due to the formation of transformation products. An increase in toxicity units (from 13.64 to 87.86 at the end) was associated with the accumulation of 3-hydroxybutyl dihydrogen phosphate (OH-MBP). However, subsequent experiments demonstrated that given sufficient time, the fungus not only degraded OH-MBP but also produced a non-toxic effluent.

Mechanism of microplastics promoting sulfamethoxazole biodegradation in activated sludge as revealed by DNA-stable isotope probing

Microplastics (MPs) often coexist with sulfonamide antibiotics (SAs) in the activated sludge of wastewater treatment plants (WWTPs). Microbial degradation is a crucial pathway for SAs removal in the activated sludge, though its response to MPs still yet to be disclosed. Here, we combined DNA-stable isotope probing (DNA-SIP), PICRUSt and MENA techniques to explore the impact of MPs on the microbial biodegradation of sulfamethoxazole (SMX) in the activated sludge. DNA-SIP revealed 20 genera were responsible for the SMX degradation in the activated sludge, with 13 of these genera being firstly linked with sulfonamide biodegradation. The potential SMX-degrading bacteria showed complex synergistic interaction with the other microbes. Eight degradation pathways were constructed based on the nine identified SMX-related degradation genes. MPs addition enhanced the SMX biodegradation by altering the structure of degrading microbes, increasing their relative abundance and promoting the synergistic interactions between potential SMX-degrading bacteria and other microbes in activated sludge. Besides, genes related to abundant energy production and biofilm formation were involved in SMX degradation in the activated sludge with MPs. Our study reveals the MPs influence on SMX biodegradation in activated sludge, and disclose the potential underlying mechanisms, which will benefit the regulation on antibiotic removal in WWTPs.

Cultivation of Top Innovative Talents Leads the Formation of New Quality Productivity: Ideal Picture, Realistic Dilemma and Practical Way Forward

Top-tier innovative talents possess characteristics of innovation, leadership, sociality, timeliness, and openness, which meet the needs of the development of new quality productivity. Vigorously cultivating top-tier innovative talents is a key factor in leading the formation of new quality productivity. The cultivation of top-tier innovative talents generates the connotation of new quality productivity, and the formation of new quality productivity also influences the training concepts and quality structure of top-tier innovative talents. There is an inherent logic of two-way drive and mutual promotion between the two. With the acceleration of the current new round of scientific and technological revolution and industrial transformation, the cultivation of top-tier innovative talents leading to the formation of new quality productivity faces practical dilemmas such as the lack of future-oriented thinking in talent cultivation, insufficient coordination in the talent cultivation system, and a lack of diversity in the types of talent cultivation. It is necessary to take a holistic approach, focusing on integrating educational resources, incubating cross-border innovation, advancing human-machine cooperation, adhering to open training, and highlighting regional characteristics to continuously exert efforts, explore new paths for the cultivation of top-tier innovative talents, and lay a talent foundation for accelerating the formation of new quality productivity. aggressive behavior in older preschoolers has long been a nuisance to kindergarten teachers and parents, and it is a common yet difficult problem in society. This study recorded the proportion, context, and reasons for aggressive behavior in older preschoolers at the Tianfu New Area Experimental Kindergarten in Chengdu. Combining the physical and mental development patterns of older preschoolers, methods such as observation records and situational analysis were used. Through real confrontation, observation, analysis, and exploration, effective ways to reduce and correct aggressive behavior in older preschoolers were found, with the aim of helping teachers cope with such behaviors.

Genome-Wide Identification and Characterization of the Laccase Gene Family in Fragaria vesca and Its Potential Roles in Response to Salt and Drought Stresses

Laccase (LAC, EC 1.10.3.2) is integral to the formation of lignin synthesis, flavonoid production, and responses to both biotic and abiotic stresses. While recent studies have characterized numerous LAC gene families and their functions across various plants, information regarding LAC genes in woodland strawberry (Fragaria vesca) remains limited. In this study, we identified a total of 57 FvLAC genes in the Fragaria vesca genome, which were phylogenetically categorized into five distinct groups. Analysis of the gene structures revealed a uniformity in the exon–intron structure among the subgroups, while conserved motifs identified unique motifs specific to certain subgroups, suggesting functional variations. Chromosomal localization studies indicated that FvLACs are distributed across seven chromosomes, and collinearity analysis demonstrated that FvLACs exhibit collinearity within the species. Additionally, cis-acting element analysis suggested that FvLAC genes are involved in stress responses, hormone responses, light responses, and the growth and development of plants. qRT-PCR demonstrated that FvLACs responded to salt, drought, and hormone stresses, with the expression levels of FvLAC24, FvLAC32, and FvLAC51 continuously increasing under these stress conditions. Furthermore, transgenic yeast experiments revealed that FvLAC51 enhanced yeast tolerance to both salt and drought stresses, while FvLAC24 and FvLAC32 negatively regulated yeast tolerance under these same conditions. These findings provide a theoretical foundation for further investigation into the functions of FvLAC genes in woodland strawberry.