Interfacial Modification of ZnO/ZnMgO Bilayer for Efficient and Stable InP Quantum Dot Light-Emitting Diodes via Ultraviolet Ozone Treatment.

The development of efficient charge transport layers is crucial for realizing high-performance and stable quantum dot light-emitting diodes (QD-LEDs). The use of a ZnO/ZnMgO bilayer as an electron transporting layer (ETL) has garnered considerable attention. This configuration leverages the high electron mobility of ZnO and the favorable surface state of ZnMgO. Furthermore, the versatility of this configuration extends to its wide range of thickness tunability, rendering it suitable for the construction of thick devices for top-emitting structures with microcavities. However, despite the promising attributes of this bilayer configuration, the impact of the ZnO/ZnMgO bilayer ETL interface on QD-LEDs performance remains largely unexplored. Thus, this study investigated the effect of ultraviolet ozone (UVO) treatment on the stabilization of the ZnO/ZnMgO interface. UVO treatment was found to significantly enhance luminance uniformity across the QD-LEDs emission area while improving operational stability by over 4-fold. Comprehensive analyses employing X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy confirmed that UVO treatment significantly reduced the defect states of the hydroxyl groups and removed the insulating native ethanolamine ligands, thereby facilitating improved and uniform electron transport. Moreover, the effectiveness of UVO treatment in enhancing electron transport was supported by impedance analyses. Therefore, this paper presents an effective approach for enhancing the interface of a highly potent ZnO/ZnMgO bilayer ETL, which can ultimately improve the luminance uniformity and stability of QD-LEDs.

D-Hexopyranosides with Vicinal Nitrogen-Containing Functionalities.

Various substituted D-hexopypyranosides units with nitrogen-containing functionalities are present in many important natural compounds and pharmaceutical substances. Since their complex structural diversity contributes to a broad spectrum of biological functions and activities, these derivatives are frequently studied. This review covers syntheses of D-hexopyranosides with vicinal nitrogen-containing functionalities since the 1960s, when the first articles emerged. The syntheses are arranged according to the positions of substitutions, to form a relative configuration of vicinal functionalities, and synthetic methodologies.

Insights into the Photochemical Mechanism of Goethite: Roles of Different Types of Surface Hydroxyl Groups in Reactive Oxygen Species Generation and Fe(III) Reduction.

The surface photochemical activity of goethite, which occurs widely in surface soils and sediments, plays a crucial role in the environmental transformation of various pollutants and natural organic matter. This study systemically investigated the mechanism of different types of surface hydroxyl groups on goethite in generating reactive oxygen species (ROSs) and Fe(III) reduction under sunlight irradiation. Surface hydroxyl groups were found to induce photoreductive dissolution of Fe(III) at the goethite-water interface to produce Fe2+(aq), while promoting the production of ROSs. Substitution of the surface hydroxyl groups on goethite by fluoride significantly inhibited the photochemical activity of goethite, demonstrating their important role in photochemical activation of goethite. The results showed that the surface hydroxyl groups (especially the terminating hydroxyl groups, ≡FeOH) led to the formation of Fe(III)-hydroxyl complexes via ligand-metal charge transfer on the goethite surface upon photoexcitation, facilitating the production of Fe2+(aq) and •OH. The bridging hydroxyl groups (≡Fe2OH) were shown to mainly catalyze the production of H2O2, leading to the subsequent light-driven Fenton reaction to produce •OH. These findings provide important insights into the activation of molecular oxygen on the goethite surface driven by sunlight in the environment, and the corresponding degradation of anthropogenic and natural organic compounds caused by the generated ROSs.

Practical synthesis of chenodeoxycholic acid from phocaecholic acid.

In this study, we developed an effective method for the large-scale synthesis of chenodeoxycholic acid (CDCA) from phocaecholic acid (PhCA). A high total yield of up to 72 % was obtained via five steps including methyl esterification, Ts-protection, bromination, reduction, and hydrolysis. The structures of the intermediates were confirmed by 1H NMR (Nuclear Magnetic Resonance), 13C NMR, HRMS (High Resolution Mass Spectrometry), and IR (Infrared Spectroscopy) spectroscopies. This method offers a new and practical approach to the synthesizing of CDCA.

Designing High Performance Carbon/ZnSn(OH)6-Based Humidity Sensors.

In this work, pure phase and carbon/ZnSn(OH)6 samples were synthesized by a hydrothermal method. The composite sample's structure, morphology, and functional groups were investigated by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. Subsequently, ZnSn(OH)6 samples were modified with different carbon contents, and their humidity-sensing properties were investigated. The introduction of carbon increased the specific surface area of pure ZnSn(OH)6 samples, thus significantly improving the sensors' humidity sensing response. The C10-ZnSn(OH)6 sensor exhibited a high response, up to three orders of magnitude, a humidity hysteresisof 13.5%, a fast response time of 3.2 s, and a recovery time of 24.4 s. The humidity sensor's possible humidity sensing mechanism was also analyzed using the AC complex impedance puissance method with a simulated equivalent circuit. These results revealed that ZnSn(OH)6 can effectively detect ambient humidity and that the introduction of carbon significantly improves its humidity-sensing performance. The study provides an effective strategy for understanding and designing ZnSn(OH)6-based humidity sensors.

DFT and AIMD insights into heterogeneous dissociation of 2-chlorothiophenol on CuO(111) surface: Impact of H2O and OH.

Copper oxides are vital catalysts in facilitating the formation of polychlorinated thianthrenes/dibenzothiophenes (PCTA/DTs) through heterogeneous reactions in high-temperature industrial processes. Chlorothiophenols (CTPs) are the most crucial precursors for PCTA/DT formation. The initial step in this process is the metal-catalyzed production of chlorothiophenoxy radicals (CTPRs) from CTPs via dissociation reactions. This work combines density functional theory (DFT) calculations with ab initio molecular dynamics (AIMD) simulations to explore the formation mechanism of the adsorbed 2-CTPR from 2-CTP, with the assistance of CuO(111). Our study demonstrates that flat adsorption configurations of 2-CTP on the CuO(111) surface are more stable than vertical configurations. The CuO(111) surface acts as a strong catalyst, facilitating the dissociation of 2-CTP into the adsorbed 2-CTPR. Surface oxygen vacancies enhance the adsorption of 2-CTP on the CuO(111) surface, while moderately suppressing the dissociation of 2-CTP. More importantly, water molecules and surface hydroxyl groups actively promote the dissociation of 2-CTP. Specifically, water directly participates in the reaction through "water bridge", enabling a barrier-free process. This research provides molecular-level insights into the heterogeneous generation of dioxins with the catalysis of metal oxides in fly ash from static and dynamic aspects, providing novel approaches for reducing dioxin emissions and establishing dioxin control strategies.

Synergetic effects of Mn(II) production and site availability on arsenite oxidation and arsenate adsorption on birnessite in the presence of low molecular weight organic acids.

Manganese oxides and organic acids are key factors affecting arsenic mobility, but As(III) oxidation and adsorption in the coexistence of birnessite and low molecular weight organic acids (LMWOAs) are poorly understood. Herein, As(III) immobilization by birnessite was investigated with/without LMWOAs (including tartaric (TA), malate (MA), and succinic acids (SA) with two, one and zero hydroxyl groups, respectively). In the low-As(III) system with less Mn(II) production, LMWOAs generally inhibited As(III) oxidation. The slower decrease in As(III) concentration in TA-amended batches resulted from stronger bonding interaction between TA and edge sites, evidenced by higher removal of TA than MA and SA in solutions and the higher proportion of shifted C-OH component in solids. In high-As(III) systems with abundant Mn(II) production, higher concentrations of dissolved Mn and Mn(III) in LMWOA-amended batches than in LMWOA-free batches revealed that LMWOA-induced complexing dissolution caused the release of adsorbed Mn(II), which was conducive to As(III) oxidation and As(V) adsorption onto the edge sites. The lowest concentrations of dissolved Mn and Mn(III) in TA-amended batches indicated that the hydroxyl group constrained complexing dissolution. This study reveals that concentrations of produced Mn(II) determined the roles of LMWOAs in As(III) behavior and highlights the impacts of the hydroxyl group on arsenic mobility.

Synergy of Paired Brønsted-Lewis Acid Sites on Defects of Zr-MIL-140A for Methanol Dehydration.

As a common defect-capping ligand in metal-organic frameworks (MOFs), the hydroxyl group normally exhibits Brønsted acidity or basicity, but the presence of inherent hydroxyl groups in the MOF structure makes it a great challenge to identify the exact role of defect-capping hydroxyl groups in catalysis. Herein, we used hydroxyl-free MIL-140A as the platform to generate terminal hydroxyl groups on defect sites via a continuous post-synthetic treatment. The structure and acidity of MIL-140A were properly characterized. The hydroxyl-contained MIL-140A-OH exhibited 4.6-fold higher activity than the pristine MIL-140A in methanol dehydration. Spectroscopic and computational investigations demonstrated that the reaction was initiated by the respective adsorption of two methanol molecules on the terminal-OH and the adjacent Zr vacancy. The dehydration of the adsorbed methanol molecules then occurred in the Brønsted-Lewis acid site co-participated associative pathway with the lowest energy barrier.

Intracellular stress caused by composite resins: An in vitro study using a bioluminescent antioxidant-responsive element reporter assay.

Context: Elucidating the effects of leachates from composite resins (CRs) on cells by examining the transcription level of detoxification genes and the antioxidant-responsive element (ARE), would be helpful in clinical practice. Aims: The aim of the study is to investigate the cytotoxicity of commercially available CRs, we used a reporter assay system to evaluate intracellular stress based on ARE-mediated transcription. Setting and Design: The study design was an in vitro study. Materials and Methods: Seven kinds of CRs were each placed in four-well plates to which culture medium was added and then light-cured. The prepared samples were used either immediately (sample A) or after incubation at 37°C for 24 h (sample B) in the subsequent ARE-luciferase reporter assay, in which HepG2 cells stably expressing an ARE-regulated luciferase reporter gene (HepG2-AD13 cells) were cultured for 6 h in culture media with the CR eluate (samples A or B) or without (control) (n = 4). In the cell viability assay, cell viability in various solutions with the same incubation time was confirmed by MTT assay (n = 4). Statistical analysis was performed using the paired t-test and one-way analysis of variance. Results: All CR solutions showed an increase in ARE activation rate; a CR with spherical nanofillers showed the highest ARE activation rate of 108.5-fold in sample A. Cell viability was not significantly reduced for any of the CRs in sample A. However, the CR-containing bisphenol A-glycidyl methacrylate (Bis-GMA) caused a significant decrease in cell viability in sample B. Conclusions: The intracellular stress in the viable cells differed among the CRs, depending on the type of monomer used. In particular, Bis-GMA-containing hydroxyl groups showed high cytotoxicity.

Role of the surface characteristics of hyper-crosslinked polymers on the transformation of adsorbed trichlorophenol: Implications for understanding the surface reactivity of biochar derived from waste biomass.

The surface reactivity of biochar derived from waste biomass has not been well understood due to its complex composition and heterogeneity. Therefore, this study synthesized a series of biochar-like hyper-crosslinked polymers (HCPs) with different amounts of phenolic hydroxyl groups on the surface as an indicative tool to investigate the roles of key surface properties of biochar on transforming pollutants being adsorbed. Characterization of HCPs suggested that electron donating capacity (EDC) of different HCPs was positively correlated with increasing amounts of phenol hydroxyl groups, whereas specific surface area, degree of aromatization and graphitization were negatively correlated. It was found that greater amounts of hydroxyl radicals were produced with increasing amounts of hydroxyl groups on the synthesized HCPs. Batch degradation experiments with trichlorophenols (TCPs) suggested that all HCPs could decompose TCP molecules upon contact. The degree of TCP degradation (~45 %) was highest for HCP made from benzene monomer with the lowest amounts of hydroxyl groups, which was likely driven by its greater specific surface area and reactive sites for TCP degradation. Conversely, the degree of TCP degradation (~25 %) by HCPs with the highest hydroxyl group abundance was the lowest, probably because the lower surface area of HCPs had limited TCP adsorption, which led to lower interaction between HCP surface and TCP molecules. The results concluded from the contact of HCPs and TCP suggested both EDC and adsorption capacity of biochar played critical roles in transforming organic pollutants.

Effect of Hydroxyl Group on Photo-Physical Properties and Dipole Moments of Fluorescent Dyes: An Experimental and Computational Approach.

In this work, structurally similar, (E)-N'-(2-hydroxybenzylidene)-3,5-di-tert-butyl-2-hydroxybenzohydrazide (A) and (E)-N'-(2-4-dihydroxybenzylidene)-3,5-di-tert-butyl-2-hydroxybenzohydrazide (A-OH) dyes dissolved in general solvents have been studied to explore photo-physical properties, employing solvatochromic shift method, thereby determining their dipole moments in the ground (µg) and excited (µe) states. The molecule A shows a bathochromic shift of fluorescence emission maxima in aprotic solvents whereas a hypsochromic shift in protic solvents. Interestingly, A-OH follows a hypsochromic shift in both protic and aprotic solvents with increasing solvent polarity. The effect of hydroxyl substituent on UV-Visible absorption, fluorescence emission, and dipole moment of the titled organic molecules was explained. Theoretical methods such as Bilot-Kawski method for determination of µg and µe and Bakshiev, Kawski-Chamma-Viallet, Lippert-Mataga equations for µe, and Reichardt method for the difference between µg and µe were employed. It is observed that µe is higher than that of µg for both the molecules, and interestingly, upon substituting an additional hydroxyl group the value of µg has increased while µe is decreased. The DFT calculations have been performed to support experimental results by employing DFT/B3LYP/6-311G + (d) and TD-DFT/B3LYP/6-311G + (d) method using Gaussian09 software. The electrophilic and nucleophilic sites on the molecules were studied with the help of MEP. The NBO analysis results show that the interaction N24 (σ) → C22-O23 (π*) is found to be stronger in both the molecules with energy 68.90 kJ/mol and the effect of hydroxyl group is also discussed on the basis of HOMO and LUMO.

Analysis of the Factors Affecting the Configuration of the Anti-parallel G-quadruplex Formed by 22-nt Telomere RNA Fragments / 中国生物化学与分子生物学报

G-quadruplexes with different conformations often exhibit different binding abilities to proteins and play different physiological functions. It is of great significance to analyze the factors affecting the configuration of G-quadruplex to explore its physiological function. Different from DNA, RNA sequences have shown parallel G-quadruplex structures in previous reports. However, we found that the only RNA sequence, the 22-nt telomere RNA fragment (ORN-N, A

Insight into phase structure-dependent soot oxidation activity of K/MnO2 catalyst.

In the present study, two nanosized MnO2 with ß and δ phase structures and potassium loaded MnO2 catalysts with varied K loading amounts (denoted as K/MnO2) were prepared. Temperature programmed oxidation and isothermal reactions in loose contact modes were employed to examine the soot oxidation activity of the as-prepared catalysts. Characterization results show that as compared with ß-MnO2, δ-MnO2 has larger surface area and higher content of hydroxyl groups. Upon K loading, abundant hydroxyl groups in δ-MnO2 effectively sequestrate K cation to form bound K species and free K species are available only at K loading above 3.0 wt.%. In contrast, the majority of K species present as free state in ß-MnO2 even at a K loading of 1.0 wt.% due to its very low hydroxyl group content. The O2 temperature-programmed desorption (O2-TPD) demonstrates that the catalysts with free K species exhibit strong ability in activating gaseous O2, whereas the catalysts only having bound K display minor O2 activation capability. As a result, despite of slightly lower activity of ß-MnO2 than δ-MnO2, the K/ß-MnO2 catalysts exhibit substantially higher activities than K/δ-MnO2 catalysts with identical K loadings. The finding in this study clearly demonstrates that for MnO2 based catalysts, the enhancement of catalytic activity for soot oxidation is highly K loading amount dependent and the dependency is strongly associated with the phase structure of MnO2.

Regulating the electronic structures of mixed B-site pyrochlore to enhance the turnover frequency in water oxidation.

This paper describes the development of mixed B-site pyrochlore Y2MnRuO7 electrocatalyst for oxygen evolution reaction (OER) in acidic media, a challenge for the development of low-temperature electrolyzer for green hydrogen production. Recently, several theories have been developed to understand the reaction mechanism for OER, though there is an  uncertainty in most of the cases, due to the complex surface structures. Several key factors such as lattice oxygen, defect, electronic structure, oxidation state, hydroxyl group and conductivity were identified and shown to be important to the OER activity. The contribution of each factor to the performance however is often not well understood, limiting their impact in guiding the design of OER electrocatalysts. In this work, we showed mixed B-site pyrochlore Y2MnRuO7 catalyst exhibits 14 times higher turnover frequency (TOF) than RuO2 while maintaining a low overpotential of ~ 300 mV for the entire testing period of 24 h in acidic electrolyte. X-ray photoelectron spectroscopy (XPS) analysis reveals that this B-site mixed pyrochlore Y2MnRuO7 has a higher oxidation state of Ru than those of Y2Ru2O7, which could be crucial for improving OER performance as the broadened and lowered Ru 4d band resulted from the B-site substitution by Mn is beneficial to the OER kinetics.

Functional group substitutions influence the binding of benzophenone-type UV filters with DNA.

As a class of possible carcinogens, benzophenone-type UV filters (BPs) widely exist in natural environments and organisms. The crucial step of the carcinogenic process induced by cancerous toxins is binding with DNA to form adducts. Here, the binding of 10 typical BPs, i.e., benzophenone (BP1), 2-hydroxyl benzophenone (BP2), 4-hydroxyl benzophenone (BP3), 2,2'-dihydroxyl benzophenone (BP4), 2,4-dihydroxyl benzophenone (BP5), 4,4'-dihydroxyl benzophenone (BP6), 2,4,4'-trihydroxyl benzophenone (BP7), 2,2',4,4'-tetrahydroxyl benzophenone (BP8), 2-hydroxyl-4-methoxyl benzophenone (BP9), and 2,2'-dihydroxyl-4-methoxyl benzophenone (BP10), with DNA was tested via fluorescence quenching experiments. Only hydroxyl group-substituted BPs could bind to DNA by groove binding mode, and the quenching constants were 0.93 × 103-5.89 × 103 L/mol. Substituted BPs were preferentially bound to thymine. Circular dichroism analysis confirmed that BPs could affect DNA base stacking but could not transform its B-form. Based on molecular electrostatic surface potential analyses, molecular dynamics simulations, and energy decomposition calculations, it could be found that the site and number of hydroxyl substitution changed the molecular polarity of BPs, thereby affecting the number and strength of hydrogen bonds between BPs and DNA. The hydroxyl substitution at site 2 was more conducive to binding than at site 4. This study is beneficial in comprehending the carcinogenic mechanisms of BPs.

Preparation and Characterization of Diene Rubbers/Silica Composites via Reactions of Hydroxyl Groups and Blocked Polyisocyanates.

To improve the curing reaction rate and efficiency of sulfur-cured diene-based rubbers, the introduction of some chemical compounds as activators and accelerants is inevitably required, causing potential harm to humans and ecological systems. Moreover, silica is usually employed as a green filling material for rubber reinforcement, and a silane coupling agent is always required to improve its dispersion. Herein, we reported an effective method to cure hydroxyl-functionalized rubbers/silica composites with blocked polyisocyanates, avoiding the use of any other additives. The enhanced dispersion of silica by interaction with hydroxyl groups on molecular chains endowed the composites with high-mechanical performance. The mechanical properties and crosslinking kinetics of the resultant silica composites can be regulated by adjusting the content of hydroxyl groups in the rubber, as well as the amount of the blocked polyisocyanates. The dynamic heat build-up was related to the distance between crosslinking points. A SBROH/B-TDI/silica composite prepared with blocked toluene diisocyanatem (TDI) exhibited comparable tanδ (0.21 at 0 °C and 0.11 at 60 °C) to that of silica composites cured by sulfur with the help of a silane coupling agent (SBR/S/Si69/silica, 0.18 and 0.10), suggesting great applicable potential for new tire rubber compounds.

Topoisomerase IIα inhibitory and antiproliferative activity of dihydroxylated 2,6-diphenyl-4-fluorophenylpyridines: Design, synthesis, and structure-activity relationships.

A new series of fifty-four 2-phenol-4-aryl-6-hydroxyphenylpyridines containing fluorophenyl, trifluoromethylphenyl, and trifluoromethoxy phenyl groups were synthesized and tested for topoisomerase IIα inhibitory and antiproliferative activity against different cancer cell lines in an attempt to look into topoisomerase IIα-targeted prospective anticancer agents to counter the limitations of available treatment options. When compared to positive controls, several compounds 11-12, 37, 50, and 51 showed high antiproliferative activity, while several 4-fluorophenyl substituted compounds 13-14 and 18 showed strong topoisomerase IIα inhibition. Surprisingly, most of the compounds had a significant antiproliferative effect on the HCT15 colorectal adenocarcinoma and T47D breast cancer cell lines. Moreover, compound 12 with para-fluorophenyl at the 4-position and meta-phenolic groups at the 2- and 6-positions inhibited proliferating HeLa cervix adenocarcinoma cells with an IC50 value of 1.28 µM. Based on biological results, the structure-activity relationships of the synthesized derivatives emphasized the significance of 4-trifluoromethoxyphenyl groups for strong antiproliferative activity and 4-fluorophenyl groups for strong topo IIα inhibition. Furthermore, meta- and para-phenolic groups at the 2- and 4-positions are favorable for strong topo IIα inhibitory and antiproliferative activity. The research findings provide insight into the effect of different fluorine functionalities in the discovery of novel topoisomerase IIα-targeted anticancer agents.

The immunomodulatory activity of degradation products of Sesbania cannabina galactomannan with different molecular weights.

Galactomannan (GM) is widely recognized as an immune enhancer; however, the underlying molecular mechanism is still unknown. Herein, four products with molecular weights in descending order, namely GM40, GM50, GM65, and GMOS, were separated from incomplete degradation products of Sesbania cannabina GM by ethanol precipitation, followed by their immunomodulatory activity. Through FTIR and XPS spectra, the amount of free hydroxyl groups was shown to decrease in the following order: GM > GM50 > GMOS > GM40 > GM65. Moreover, the immunomodulatory activity of different products decreased in abovementioned order. The TNF-α, IL-6 and TLR4 content in RAW 264.7 cells treated with different GM products in the presence or absence of TAK-242 (TLR4 inhibitor) suggested that the immunomodulatory activity of GM and its degradation products is TLR4-dependent. Overall, the preliminary relationship indicated here between the hydroxyl groups or the possible deeper structural changes of GM and the immunomodulatory activity need to be further investigated.

Crystal face dependent wettability of α-quartz: Elucidation by time-of-flight secondary ion mass spectrometry techniques combined with molecular dynamics.

HYPOTHESIS: Quartz is one of the most common but important minerals, and its wettability plays a significant role in affecting various natural and industrial processes. Studies have revealed that different crystal faces of quartz are with different wettabilities, but its mechanism is still vague. EXPERIMENTS AND SIMULATIONS: For specifying the mechanism of crystal face dependent wettability, the contact angles of three different liquids on the crystal faces of α-quartz are measured; the time-of-flight secondary ion mass spectrometry (ToF-SIMS) is employed to establish the crystal surface models; molecular dynamics (MD) simulations with the surface models are performed to understand the wetting behavior at molecular scale. FINDINGS: Based on the contact angle measurements, the wettabilities of different crystal faces of α-quartz are found different, which can be directly attributed to the concentration of hydroxyl group on crystal faces based on ToF-SIMS results. MD simulations yield consistent results with the contact angle order recognized from experiments, revealing that the surface hydroxyl group controls the wettability of α-quartz crystal faces. It is also recognized that the pristine surface atomic arrangement, especially the surface concentration of unsaturated bond (an intrinsic property of α-quartz), is the intrinsic cause of the difference in the concentration of hydroxyl group of the crystal surface.

Diastereoselective Alkene Hydroesterification Enabling the Synthesis of Chiral Fused Bicyclic Lactones.

Palladium-catalysed diastereoselective hydroesterification of alkenes assisted by the coordinative hydroxyl group in the substrate afforded a variety of chiral γ-butyrolactones bearing two stereocenters. Employing the carbonylation-lactonization products as the key intermediates, the route from the alkenes with single chiral center to chiral THF-fused bicyclic γ-lactones containing three stereocenters was developed.