-
Angewandte Chemie (International Ed. in... Jul 2024An organophosphorus redox-catalyzed method for the direct electrophilic cyanation of C(sp2)-H nucleophiles with sodium cyanate (NaOCN) is reported. The catalytic...
An organophosphorus redox-catalyzed method for the direct electrophilic cyanation of C(sp2)-H nucleophiles with sodium cyanate (NaOCN) is reported. The catalytic deoxyfunctionalization of the OCN- anion is enabled by the use of a small-ring phosphacyclic (phosphetane) catalyst in combination with a terminal hydrosilane O-atom acceptor and a malonate-derived bromenium donor. In situ spectroscopy under single-turnover conditions demonstrate that insoluble inorganic cyanate anion is activated by bromide displacement on a bromophosphonium catalytic intermediate to give a reactive N-bound isocyanatophosphonium ion, which delivers electrophilic "CN+" equivalents to nucleophilic (hetero)arenes and alkenes with loss of a phosphine oxide. These results demonstrate the feasibility of deoxyfunctionalization of insoluble inorganic salts by PIII/PV=O catalyzed phase transfer activation.
PubMed: 38950149
DOI: 10.1002/anie.202409854 -
Dental and Medical Problems 2024Despite the superiority of glass-ionomer cements (GICs) over composites in treating white spot lesions (WSLs), there is still a concern about their preventive and...
BACKGROUND
Despite the superiority of glass-ionomer cements (GICs) over composites in treating white spot lesions (WSLs), there is still a concern about their preventive and antibacterial properties. Efforts have been made to improve the strength of their bond to demineralized enamel, fluoride release and antibacterial properties by adding nanoparticles of chitosan, which seems to be a promising method.
OBJECTIVES
The aim of the present study was to assess the antibacterial effect, the microshear bond strength (μSBS) to enamel at the WSL area, and the fluoride and nano-chitosan release after modifying the polyacrylic acid liquid phase of a traditional GIC with different nano-chitosan volumes.
MATERIAL AND METHODS
A total of 120 samples were prepared, and then divided into 4 groups (n = 30): G1 - non-modified GIC, which served as a control group, while G2, G3 and G4 were modified with different nano-chitosan volumes (50%, 100% and 150%, respectively). Microshear bond strength was assessed using a universal testing machine (UTM) after storage in distilled water for 24 h. Fluoride and nanochitosan release was measured with the use of spectrophotometers at different time points (initially, and at 1 h, 24 h, 48 h, 72 h, 1 week, 2 weeks, 3 weeks, and 6 weeks) after storage in distilled water. The antibacterial effect against the Streptococcus aureus strain was assessed with the agar diffusion test. The data was statistically analyzed.
RESULTS
After 24-hour storage, G2 recorded a slight, yet non-significant, increase in the μSBS values (4.1 ±0.94 MPa) as compared to G1 (3.9 ±1.30 MPa). With regard to fluoride release, the amount recorded for G1 was significantly greater at the end of the 24-hour storage period (0.70 ±0.30 μmf/cm2) than modified nano-chitosan GIC groups; G1 was followed by G4 (0.54 ±0.34 μmf/cm2). The highest amount of nano-chitosan release after 24-hour storage was noted for G3 (0.85 ±0.00 μmf/cm2). The highest inhibition zone value was recorded for G2.
CONCLUSIONS
Glass-ionomer cement modified with 50% nano-chitosan was shown to positively affect μSBS and the antibacterial effect, while modification with 150% nano-chitosan significantly increased fluoride release.
Topics: Chitosan; Anti-Bacterial Agents; Glass Ionomer Cements; Dental Caries; In Vitro Techniques; Fluorides; Humans; Nanoparticles; Shear Strength; Dental Enamel; Materials Testing; Dental Bonding
PubMed: 38949834
DOI: 10.17219/dmp/158835 -
Environmental Monitoring and Assessment Jun 2024We assessed the hydrochemistry of 15 watersheds in the Halton Region, southern Ontario, in high resolution (n > 500 samples across n > 40 streams) to...
We assessed the hydrochemistry of 15 watersheds in the Halton Region, southern Ontario, in high resolution (n > 500 samples across n > 40 streams) to characterize water quality dynamics and governing controls on major and trace element concentrations in this rapidly urbanizing region. In 2022, major water quality parameters were generally in line with historic monitoring data yet significantly different across catchments, e.g., in specific conductance, turbidity, phosphate and chloride, and trace element concentrations. Distinct hydrochemical signatures were observed between urban and rural creeks, with urban stream sections and sites near the river mouths close to Lake Ontario having consistently higher chloride (up to 700 mg/L) and occasional enrichment in nutrients levels (up to 8 and 20 mg/L phosphate and nitrate, respectively). Particularly upper reaches exhibited hydrochemical signatures that were reflective of the catchment surface lithologies, for instance through higher dissolved Ca to Mg ratios. Unlike for chloride and phosphate, provincial water quality guidelines for trace elements and heavy metals were seldom surpassed (on < 10 occasions for copper, zinc, cadmium, and uranium). Concentrations of other trace elements (e.g., platinum group elements or rare earth elements) were expectedly low (< 0.3 µg/L) but showed spatiotemporal concentration patterns and concentration-discharge dynamics different from those of the major water quality parameters. Our results help improve the understanding of surface water conditions within Halton's regional Natural Heritage Systems and demonstrate how enhanced environmental monitoring can deliver actionable information for watershed decision-making.
Topics: Environmental Monitoring; Ontario; Water Pollutants, Chemical; Water Quality; Rivers; Trace Elements; Metals, Heavy; Chlorides; Water Pollution, Chemical
PubMed: 38949676
DOI: 10.1007/s10661-024-12833-6 -
ACS Applied Materials & Interfaces Jul 2024Electronic devices employing two-dimensional (2D) van der Waals (vdW) transition-metal dichalcogenide (TMD) layers as semiconducting channels often exhibit limited...
Electronic devices employing two-dimensional (2D) van der Waals (vdW) transition-metal dichalcogenide (TMD) layers as semiconducting channels often exhibit limited performance (e.g., low carrier mobility), in part, due to their high contact resistances caused by interfacing non-vdW three-dimensional (3D) metal electrodes. Herein, we report that this intrinsic contact issue can be efficiently mitigated by forming the 2D/2D in-plane junctions of 2D semiconductor channels seamlessly interfaced with 2D metal electrodes. For this, we demonstrated the selectively patterned conversion of semiconducting 2D PtSe (channels) to metallic 2D PtTe (electrodes) layers by employing a wafer-scale low-temperature chemical vapor deposition (CVD) process. We investigated a variety of field-effect transistors (FETs) employing wafer-scale CVD-2D PtSe/2D PtTe heterolayers and identified that silicon dioxide (SiO) top-gated FETs exhibited an extremely high hole mobility of ∼120 cm V s at room temperature, significantly surpassing performances with previous wafer-scale 2D PtSe-based FETs. The low-temperature nature of the CVD method further allowed for the direct fabrication of wafer-scale arrays of 2D PtSe/2D PtTe heterolayers on polyamide (PI) substrates, which intrinsically displayed optical pulse-induced artificial synaptic behaviors. This study is believed to vastly broaden the applicability of 2D TMD layers for next-generation, high-performance electronic devices with unconventional functionalities.
PubMed: 38949620
DOI: 10.1021/acsami.4c06540 -
Biomaterials Science Jul 2024Zwitterionic carboxyalkyl poly(1-vinylimidazole) (CA-PVIm) polymers with imidazolium cations and carboxylate anions have been synthesized as a carrier for the delivery...
Zwitterionic carboxyalkyl poly(1-vinylimidazole) (CA-PVIm) polymers with imidazolium cations and carboxylate anions have been synthesized as a carrier for the delivery of plasmid DNA (pDNA) to skeletal muscle. From differential scanning calorimetry measurements, resulting CA-PVIm had intermediate water in hydration water as a biocompatible polymer. Notably, when the pDNA and resulting CA-PVIm were mixed, slight retarded bands of the pDNA were observed in agarose gel electrophoresis, suggesting the polyion complex (PIC) formation between the pDNA and CA-PVIm despite zwitterionic polymers. Resulting PICs maintained the higher-order structure of the pDNA. Using resulting pDNA PICs, the highest pDNA expression by intramuscular injection was achieved in the PIC with 7 mol% carboxymethylated PVIm, that is, CA(7)-PVIm, observed in a widespread area by imaging system. These results suggest that the CA(7)-PVIm/pDNA PIC is effective for the diffusive delivery of the pDNA into skeletal muscle for the treatment of serious muscle diseases.
PubMed: 38949480
DOI: 10.1039/d4bm00510d -
Small (Weinheim An Der Bergstrasse,... Jul 2024Amidino-based additives show great potential in high-performance perovskite solar cells (PSCs). However, the role of different functional groups in amidino-based...
Amidino-based additives show great potential in high-performance perovskite solar cells (PSCs). However, the role of different functional groups in amidino-based additives have not been well elucidated. Herein, two multifunctional amidino additives 4-amidinobenzoic acid hydrochloride (ABAc) and 4-amidinobenzamide hydrochloride (ABAm) are employed to improve the film quality of formamidinium lead iodide (FAPbI) perovskites. Compared with ABAc, the amide group imparts ABAm with larger dipole moment and thus stronger interactions with the perovskite components, i.e., the hydrogen bonds between N…H and I anion and coordination bonds between C = O and Pb cation. It strengthens the passivation effect of iodine vacancy defect and slows down the crystallization process of α-FAPbI, resulting in the significantly reduced non-radiative recombination, long carrier lifetime of 1.7 µs, uniformly large crystalline grains, and enhances hydrophobicity. Profiting from the improved film quality, the ABAm-treated PSC achieves a high efficiency of 24.60%, and maintains 93% of the initial efficiency after storage in ambient environment for 1200 hours. This work provides new insights for rational design of multifunctional additives regarding of defect passivation and crystallization control toward highly efficient and stable PSCs.
PubMed: 38949415
DOI: 10.1002/smll.202403566 -
Inorganic Chemistry Jul 2024The effects of simulated radiolytic degradation of tri-butyl phosphate (TBP) on the chemical speciation of cerium were studied by spectrophotometry and electrochemistry...
The effects of simulated radiolytic degradation of tri-butyl phosphate (TBP) on the chemical speciation of cerium were studied by spectrophotometry and electrochemistry of TBP solutions containing increasing amounts of di--butyl phosphoric acid (HDBP), a common degradation product of TBP. Tetravalent cerium was found to exchange coordinated nitrate for the dibutyl phosphate anion, forming dinuclear complexes of the formula (CeOCe)(NO)(DBP)·3TBP ( = 0-3). Compared to Ce(IV), Ce(III) was complexed less strongly by HDBP in TBP, but HDBP displaced both nitrate and TBP to form the series of mononuclear complexes Ce(NO)(HDBP·DBP)·(3-)TBP ( = 0-3). Dibutyl phosphate coordination caused large negative shifts in the Ce(IV/III) reduction potential in TBP, indicating a strong stabilization of the tetravalent state. Electrochemical investigation of the reduction of Ce(IV) in TBP revealed it to be a two-electron process in accordance with the dinuclear nature of the organic-phase Ce(IV) complexes. The diffusion coefficients of the = 0 dinuclear Ce(IV)-nitrate-TBP complex and mononuclear Ce(III)-nitrate-TBP complex in TBP equilibrated with 7 M HNO were determined to be (1.16 ± 0.06) × 10 cm/s and (1.9 ± 0.4) × 10 cm/s, respectively, which also is consistent with the larger molecular volume of the dinuclear Ce(IV) complexes.
PubMed: 38949275
DOI: 10.1021/acs.inorgchem.4c01309 -
Physical Chemistry Chemical Physics :... Jul 2024Positronium (Ps) exhibits the ability to form energetically stable complexes with atoms and molecules before annihilation occurs. In particular, F, a halogen, shows the...
Positronium (Ps) exhibits the ability to form energetically stable complexes with atoms and molecules before annihilation occurs. In particular, F, a halogen, shows the highest reported positronium binding energy (2.95 eV) in the periodic table. Superhalogens are defined as molecules with electron affinities exceeding that of Cl (3.61 eV), the atom with the highest electron affinity. Building upon the concept of superhalogens, we can define Ps-superhalogens as molecules with Ps binding energies surpassing that of F. This study explores structural and energetic aspects of positronium and positron binding to neutral and anionic superhalogen molecules of the MX family (M = Li, Na, Be, Mg, B, Al, Si, P; X = F, Cl, Br), respectively and where k represents the highest formal valence of M. We perform multicomponent MP2 calculations for positron systems, which reveal how positron affinities vary with the type and number of halogen atoms present. The analysis of the results emphasizes the predominant role of electrostatic interactions in determining the positron affinity, with negligible effects of electronic and geometric relaxation upon positron attachment. We predict the energetic stability of 22 of the 24 PsMX complexes with respect to the chemically relevant dissociation channels: e emission, Ps emission and M-X bond breaking. Our findings reveal six MF systems that qualify as Ps-superhalogens, showing a positronium binding energy exceeding 2.95 eV. Of these, AlF stands out by setting a new record for the highest positronium binding energy among neutral molecules, reaching 4.36 eV.
PubMed: 38948936
DOI: 10.1039/d4cp01221f -
Sichuan Da Xue Xue Bao. Yi Xue Ban =... May 2024This study aims to systematically evaluate the protective role of quercetin (QCT), a naturally occurring flavonoid, against oxidative damage in human endometrial stromal...
OBJECTIVE
This study aims to systematically evaluate the protective role of quercetin (QCT), a naturally occurring flavonoid, against oxidative damage in human endometrial stromal cells (HESCs) induced by hydrogen peroxide (HO). Oxidative stress, such as that induced by HO, is known to contribute significantly to cellular damage and has been implicated in various reproductive health issues. The study is focused on investigating how QCT interacts with specific molecular pathways to mitigate this damage. Special attention was given to the p38 MAPK/NOX4 signaling pathway, which is crucial to the regulation of oxidative stress responses in cellular systems. By elucidating these mechanisms, the study seeks to confirm the potential of QCT not only as a protective agent against oxidative stress but also as a therapeutic agent that could be integrated in treatments of conditions characterized by heightened oxidative stress in endometrial cells.
METHODS
cultures of HESCs were treated with QCT at different concentrations (0, 10, 20, and 40 μmol/L) for 24 h to verify the non-toxic effects of QCT on normal endometrial cells. Subsequently, 250 μmol/L HO was used to incubate the cells for 12 h to establish an HO-induced HESCs injury model. HESCs were pretreated with QCT for 24 h, which was followed by stimulation with HO. Then, CCK-8 assay was performed to examine the cell viability and to screen for the effective intervention concentration. HESCs were divided into 3 groups, the control group, the HO model group, and the HO+QCT group. Intracellular levels of reactive oxygen species (ROS) were precisely quantified using the DCFH-DA fluorescence assay, a method known for its accuracy in detecting and quantifying oxidative changes within the cell. The mitochondrial membrane potential was determined by JC-1 staining. Annexin Ⅴ/PI double staining and flow cytometry were performed to determine the effect of QCT on HO-induced apoptosis of HESCs. Furthermore, to delve deeper into the cellular mechanisms underlying the observed effects, Western blot analysis was conducted to measure the expression levels of the critical proteins involved in oxidative stress response, including NADPH oxidase 4 (NOX4), p38 mitogen-activated protein kinase (p38 MAPK), and phosphorylated p38 MAPK (p-p38 MAPK). This analysis helps increase understanding of the specific intracellular signaling pathways affected by QCT treatment, giving special attention to its potential for modulation of the p38 MAPK/NOX4 pathway, which plays a significant role in cellular defense mechanisms against oxidative stress.
RESULTS
In this study, we started off by assessing the toxicity of QCT on normal endometrial cells. Our findings revealed that QCT at various concentrations (0, 10, 20, and 40 μmol/L) did not exhibit any cytotoxic effects, which laid the foundation for further investigation into its protective roles. In the HO-induced HESCs injury model, a significant reduction in cell viability was observed, which was linked to the generation of ROS and the resultant oxidative damage. However, pretreatment with QCT (10 μmol/L and 20 μmol/L) significantly enhanced cell viability after 24 h (<0.05), with the 20 μmol/L concentration showing the most substantial effect. This suggests that QCT can effectively reverse the cellular damage caused by HO. Furthermore, the apoptosis assays demonstrated a significant increase in the apoptosis rates in the HO model group compared to those in the control group (<0.01). However, co-treatment with QCT significantly reversed this trend (<0.05), indicating QCT's potential protective role in mitigating cell apoptosis. ROS assays showed that, compared to that in the control group, the average fluorescence intensity of ROS in the HO model group significantly increased (<0.01). QCT treatment significantly reduced the ROS fluorescence intensity in the HO+QCT group compared to the that in the HO model group, suggesting an effective alleviation of oxidative damage (<0.05). JC-1 staining for mitochondrial membrane potential changes revealed that compared to that in the control, the proportion of cells with decreased mitochondrial membrane potential significantly increased in the HO model group (<0.01). However, this proportion was significantly reduced in the QCT-treated group compared to that of the HO model group (<0.05). Finally, Western blot analysis indicated that the expression levels of NOX4 and p-p38 MAPK proteins were elevated in the HO model group compared to those of the control group (<0.05). Following QCT treatment, these protein levels significantly decreased compared to those of the HO model group (<0.05). These results suggest that QCT may exert its protective effects against oxidative stress by modulating the p38 MAPK/NOX4 signaling pathway.
CONCLUSION
QCT has demonstrated significant protective effects against HO-induced oxidative damage in HESCs. This protection is primarily achieved through the effective reduction of ROS accumulation and the inhibition of critical signaling pathways involved in the oxidative stress response, notably the p38 MAPK/NOX4 pathway. The results of this study reveal that QCT's ability to modulate these pathways plays a key role in alleviating cellular damage associated with oxidative stress conditions. This indicates not only its potential as a protective agent against cellular oxidative stress, but also highlights its potential for therapeutic applications in treating conditions characterized by increased oxidative stress in the endometrium, thereby offering the prospect of enhancing reproductive health. Future studies should explore the long-term effects of QCT and its clinical efficacy , thereby providing a clear path toward its integration into therapeutic protocols.
Topics: Humans; Hydrogen Peroxide; Oxidative Stress; Female; NADPH Oxidase 4; Quercetin; Endometrium; p38 Mitogen-Activated Protein Kinases; Stromal Cells; Signal Transduction; Reactive Oxygen Species; Apoptosis; Cells, Cultured
PubMed: 38948281
DOI: 10.12182/20240560107 -
Sichuan Da Xue Xue Bao. Yi Xue Ban =... May 2024To investigate the effect of Sanshentongmai (SSTM) mixture on the regulation of oxidative damage to rat cardiomyocytes (H9C2) through microRNA-146a and its mechanism.
OBJECTIVE
To investigate the effect of Sanshentongmai (SSTM) mixture on the regulation of oxidative damage to rat cardiomyocytes (H9C2) through microRNA-146a and its mechanism.
METHODS
H9C2 were cultured , HO was used as an oxidant to create an oxidative damage model in H9C2 cells. SSTM intervention was administered to the H9C2 cells. Then, the changes in HO-induced oxidative damage in H9C2 cells and the expression of microRNA-146a were observed to explore the protective effect of SSTM on H9C2 and its mechanism. H9C2 cells cultured were divided into 3 groups, including a control group, a model group of HO-induced oxidative damage (referred to hereafter as the model group), and a group given HO modeling plus SSTM intervention at 500 μg/L for 72 h (referred to hereafter as the treatment group). The cell viability was measured by CCK8 assay. In addition, the levels of N-terminal pro-brain natriuretic peptide (Nt-proBNP), nitric oxide (NO), high-sensitivity C-reactive protein (Hs-CRP), and angiotensin were determined by enzyme-linked immunosorbent assay (ELISA). The expression level of microRNA-146a was determined by real-time PCR (RT-PCR).
RESULT
H9C2 cells were pretreated with SSTM at mass concentrations ranging from 200 to 1500 μg/L. Then, CCK8 assay was performed to measure cell viability and the findings showed that the improvement in cell proliferation reached its peak when the mass concentration of SSTM was 500 μg/L, which was subsequently used as the intervention concentration. ELISA was performed to measure the indicators related to heart failure, including Nt-proBNP, NO, Hs-CRP, and angiotensin Ⅱ. Compared with those of the control group, the expressions of Nt-proBNP and angiotensin Ⅱ in the treatment group were up-regulated (<0.05), while the expression of NO was down-regulated (<0.05). There was no significant difference in the expression of Hs-CRP between the treatment group and the control group. These findings indicate that SSTM could effectively ameliorate oxidative damage in H9C2 rat cardiomyocytes. Finally, according to the RT-PCR findings for the expression of microRNA-146a in each group, HO treatment at 15 μmol/L could significantly reduce the expression of microRNA-146a, and the expression of microRNA-146a in the treatment group was nearly doubled compared with that in the model group. There was no significant difference between the treatment group and the control group.
CONCLUSION
SSTM can significantly resist the HO-induced oxidative damage of H9C2 cells and may play a myocardial protective role by upregulating microRNA-146a.
Topics: Myocytes, Cardiac; Animals; MicroRNAs; Rats; Oxidative Stress; Hydrogen Peroxide; Drugs, Chinese Herbal; Up-Regulation; Cell Survival; Cell Line; Drug Combinations
PubMed: 38948270
DOI: 10.12182/20240560601