Synthesis of Metal-Nitrogen-Carbon Electrocatalysts with Atomically Regulated Nitrogen-Doped Polycyclic Aromatic Hydrocarbons.

Tuning the active site structure of metal-nitrogen-carbon electrocatalysts has recently attracted increasing interest. Herein, we report a bottom-up synthesis strategy in which atomically regulated N-doped polycyclic aromatic hydrocarbons (N-PAHs) of NxC42-x (x = 1, 2, 3, 4) were used as ligands to allow tuning of the active site's structures of M-Nx and establish correlations between the structures and electrocatalytic properties. Based on the synthesis process, detailed characterization, and DFT calculation results, active structures of Nx-Fe1-Nx in Fe1-Nx/RGO catalysts were constructed. The results demonstrated that the extra uncoordinated N atoms around the Fe1-N4 moieties disrupted the π-conjugated NxC42-x ligands, which led to more localized electronic state in the Fe1-N4 moieties and superior catalytic performance. Especially, the Fe1-N4/RGO exhibited optimized performance for ORR with E1/2 increasing by 80 mV and Jk at 0.85 V improved 18 times (compared with Fe1-N1/RGO). This synthesis strategy utilizing N-PAHs holds significant promise for enhancing the controllability of metal-nitrogen-carbon electrocatalyst preparation.

Engineering Single-Atom Electrocatalysts for Enhancing Kinetics of Acidic Volmer Reaction.

The design of active and low-cost electrocatalyst for hydrogen evolution reaction (HER) is the key to achieving a clean hydrogen energy infrastructure. The most successful design principle of hydrogen electrocatalyst is the activity volcano plot, which is based on Sabatier principle and has been used to understand the exceptional activity of noble metal and design of metal alloy catalysts. However, this application of volcano plot in designing single-atom electrocatalysts (SAEs) on nitrogen doped graphene (TM/N4C catalysts) for HER has been less successful due to the nonmetallic nature of the single metal atom site. Herein, by performing ab initio molecular dynamics simulations and free energy calculations on a series of SAEs systems (TM/N4C with TM = 3d, 4d, or 5d metals), we find that the strong charge-dipole interaction between the negatively charged *H intermediate and the interfacial H2O molecules could alter the transition path of the acidic Volmer reaction and dramatically raise its kinetic barrier, despite its favorable adsorption free energy. Such kinetic hindrance is also experimentally confirmed by electrochemical measurements. By combining the hydrogen adsorption free energy and the physics of competing interfacial interactions, we propose a unifying design principle for engineering the SAEs used for hydrogen energy conversion, which incorporates both thermodynamic and kinetic considerations and allows going beyond the activity volcano model.

Ultrasonic-assisted stewing enhances the aroma intensity of chicken broth: A perspective of the aroma-binding behavior of fat.

This experiment investigated the underlying mechanism of ultrasonic-assisted stewing to enhance the aroma intensity of chicken broth by measuring fat content, oil droplet sizes, zeta potential, viscosity, surface protein loading, lipid oxidation, and aroma compound concentrations. As the thermo-ultrasound time increased, the fat content increased from 0.3 % to 1.2 %, resulting in a milky white appearance. After 1 h of thermo-ultrasound, the broth had the smallest particle size and the highest surface protein load, viscosity, and emulsion stability, as well as the highest total amount of aroma-active compounds of 314.70 ng/mg. With the further extension of thermo-ultrasound time, lipid oxidation increased, but the stability of chicken broth decreased, lowering the content of aroma-active compounds. These outcomes suggested that thermo-ultrasound could enhance the aroma intensity of chicken broth by increasing the fat content and the emulsion stability of the broth.

Pseudo-adsorption and long-range redox coupling during oxygen reduction reaction on single atom electrocatalyst.

Fundamental understanding of the dynamic behaviors at the electrochemical interface is crucial for electrocatalyst design and optimization. Here, we revisit the oxygen reduction reaction mechanism on a series of transition metal (M = Fe, Co, Ni, Cu) single atom sites embedded in N-doped nanocarbon by ab initio molecular dynamics simulations with explicit solvation. We have identified the dissociative pathways and the thereby emerged solvated hydroxide species for all the proton-coupled electron transfer (PCET) steps at the electrochemical interface. Such hydroxide species can be dynamically confined in a "pseudo-adsorption" state at a few water layers away from the active site and respond to the redox event at the catalytic center in a coupled manner within timescale less than 1 ps. In the PCET steps, the proton species (in form of hydronium in neutral/acidic media or water in alkaline medium) can protonate the pseudo-adsorbed hydroxide without needing to travel to the direct catalyst surface. This, therefore, expands the reactive region beyond the direct catalyst surface, boosting the reaction kinetics via alleviating mass transfer limits. Our work implies that in catalysis the reaction species may not necessarily bind to the catalyst surface but be confined in an active region.

Germline Variants and Genetic Interactions of Several EMT Regulatory Genes Increase the Risk of HBV-Related Hepatocellular Carcinoma.

Epithelial-mesenchymal transition (EMT) plays an important role in the development of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). We hypothesized that germline variants in the major EMT regulatory genes (SNAIL1, ZEB1, ZEB2, TWIST1) may influence the development of HBV-related HCC. We included 421 cases of HBsAg-positive patients with HCC, 1371 cases of HBsAg-positive subjects without HCC [patients with chronic hepatitis B (CHB) or liver cirrhosis (LC)] and 618 cases of healthy controls in the case-control study. Genotype, allele, and haplotype associations in the major EMT regulatory genes were tested. Environment-gene and gene-gene interactions were analysed using the non-parametric model-free multifactor dimensionality reduction (MDR) method. The SNAIL1rs4647958T>C was associated with a significantly increased risk of both HCC (CT+CC vs. TT: OR=1.559; 95% confidence interval [CI], 1.073-2.264; P=0.020) and CHB+LC (CT+CC vs. TT: OR=1.509; 95% CI, 1.145-1.988; P=0.003). Carriers of the TWIST1rs2285681G>C (genotypes CT+CC) had an increased risk of HCC (CG+CC vs. GG: OR=1.407; 95% CI, 1.065-1.858; P=0.016). The ZEB2rs3806475T>C was associated with significantly increased risk of both HCC (P recessive =0.001) and CHB+LC (P recessive<0.001). The CG haplotype of the rs4647958/rs1543442 haplotype block was associated with significant differences between healthy subjects and HCC patients (P=0.0347). Meanwhile, the CT haplotype of the rs2285681/rs2285682 haplotype block was associated with significant differences between CHB+LC and HCC patients (P=0.0123). In MDR analysis, the combination of TWIST1rs2285681, ZEB2rs3806475, SNAIL1rs4647958 exhibited the most significant association with CHB+LC and Health control in the three-locus model. Our results suggest significant single-gene associations and environment-gene/gene-gene interactions of EMT-related genes with HBV-related HCC.

Genome-wide DNA methylation and transcriptome and proteome changes in Mycobacterium tuberculosis with para-aminosalicylic acid resistance.

Previous studies have reported that genome-wide DNA methylation and differentially expressed genes and proteins are closely associated with drug resistance in Mycobacterium tuberculosis (M. tuberculosis). However, no reports have explored such associations in para-aminosalicylic acid (PAS)-resistant M. tuberculosis H37Rv. Here, we investigated genome-wide methylation and transcriptome and proteome changes to explore the associations between specific genes and PAS resistance in M. tuberculosis H37Rv. The results revealed that 1,388 differentially methylated (1,161 hypermethylated and 227 hypomethylated) genes, 214 significantly differentially expressed (103 up- and 111 down-regulated) genes and 137 differentially expressed (48 up- and 89 down-regulated) proteins were regulated by PAS in M. tuberculosis H37Rv. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that metabolic pathways and ABC transporters were closely associated with differentially methylated and expressed genes, respectively. In addition, correlation analysis revealed that differentially methylated genes were negatively correlated with their transcriptional levels in PAS-resistant M. tuberculosis H37Rv. Furthermore, the existence of five hypermethylated candidate genes (esxC, fabG3, fbpB, papA1 and pks2) in PAS-resistant M. tuberculosis H37Rv was verified using protein-protein interaction analysis in the STRING database. The integrated DNA methylation and transcriptome and proteome analysis could provide valuable resources for epigenetics studies in PAS-resistant M. tuberculosis H37Rv.

Gut microbiota alterations in moderate to severe acne vulgaris patients.

Acne vulgaris is a chronic inflammatory dermatosis affecting approximately 85% of adolescents. There are many factors contributing to the development of this ailment. A recent study indicated that gut microbiota takes part in the pathogenesis of acne. We aimed to investigate the link between acne vulgaris and gut microbiota. A total of 31 moderate to severe acne vulgaris patients and 31 healthy controls were enrolled. We collected their feces, and gut microbiota was evaluated by the hypervariable regions of 16S rRNA genes through high-throughput sequencing. We identified links between acne vulgaris and changes of gut microbiota. At the phylum level, Actinobacteria (0.89% in acne patients and 2.84% in normal controls, P = 0.004) was decreased and Proteobacteria (8.35% in acne patients and 7.01% in normal controls, P = 0.031) was increased. At the genus level, Bifidobacterium, Butyricicoccus, Coprobacillus, Lactobacillus and Allobaculum were all decreased. The observed difference in genera between acne patients and healthy controls provides a new insight into the link between gut microbiota changes and acne vulgaris risk.

Antinociceptive Diterpenoids from the Leaves and Twigs of Rhododendron decorum.

Three new leucothane-type (1-3), two new micrathane-type (4, 5), eight new grayanane-type diterpenoids (6-13), and four known compounds were obtained from the ethanol extract of the leaves and twigs of Rhododendron decorum. The structures were determined based on NMR spectra, quantum chemical calculations, and X-ray crystallography. The antinociceptive activities of compounds 1, 3, 4, 6, 8, 10-13, and 15-17 were evaluated via the acetic acid-induced writhing test. Compounds 1, 8, 11-13, and 15 exhibited significant antinociceptive activities. In particular, 12 and 15 were found to be effective at doses of 0.8 and 0.08 mg/kg, respectively.

Mechanistic Insights into the Ni-Catalyzed Reductive Carboxylation of C-O Bonds in Aromatic Esters with CO2 : Understanding Remarkable Ligand and Traceless-Directing-Group Effects.

The mechanism of the Ni0 -catalyzed reductive carboxylation reaction of C(sp2 )-O and C(sp3 )-O bonds in aromatic esters with CO2 to access valuable carboxylic acids was comprehensively studied by using DFT calculations. Computational results revealed that this transformation was composed of several key steps: C-O bond cleavage, reductive elimination, and/or CO2 insertion. Of these steps, C-O bond cleavage was found to be rate-determining, and it occurred through either oxidative addition to form a NiII intermediate, or a radical pathway that involved a bimetallic species to generate two NiI species through homolytic dissociation of the C-O bond. DFT calculations revealed that the oxidative addition step was preferred in the reductive carboxylation reactions of C(sp2 )-O and C(sp3 )-O bonds in substrates with extended π systems. In contrast, oxidative addition was highly disfavored when traceless directing groups were involved in the reductive coupling of substrates without extended π systems. In such cases, the presence of traceless directing groups allowed for docking of a second Ni0 catalyst, and the reactions proceed through a bimetallic radical pathway, rather than through concerted oxidative addition, to afford two NiI species both kinetically and thermodynamically. These theoretical mechanistic insights into the reductive carboxylation reactions of C-O bonds were also employed to investigate several experimentally observed phenomena, including ligand-dependent reactivity and site-selectivity.

A theoretical study on the oxidation of alkenes to aldehydes catalyzed by ruthenium porphyrins using O2 as the sole oxidant.

Density functional theory (DFT) calculations were used to study the ruthenium porphyrin-catalyzed oxidation of styrene to generate an aldehyde. The results indicate that two reactive oxidants, dioxoruthenium and monooxoruthenium-superoxo porphyrins, participate in the catalytic oxidation. In the mechanism, the resultant monooxoruthenium porphyrin acts in the tandem epoxide isomerization (E-I) to selectively yield an aldehyde and generate a dioxoruthenium porphyrin, thereby triggering new oxidation reaction cycles. In this calculation, several key elements responsible for the observed oxidative ability have been established by using Frontier molecular orbital (FMO) theory, natural bond orbital (NBO) analysis, etc., which include the reaction energy, the spin exchange effect, the spin-state conversion process, and the energy level of the lowest unoccupied molecular orbitals (LUMOs) of the reactive oxidants. The comparative oxidative abilities of the ruthenium-oxo/superoxo compounds with different axial ligands are also investigated. The results suggest that the ruthenium-oxo/superoxo species featuring a chlorine axial ligand is more reactive than that substituted with oxygen. This tuneable reactivity can be understood when considering the different electronic characters of the two ligands and the effective atomic number rule (EAN).

Do two oxidants (ferric-peroxo and ferryl-oxo species) act in the biosynthesis of estrogens? A DFT calculation.

Density functional theory calculations were performed in order to reveal the mysterious catalytic step of the biosynthesis of estrogens. The results indicated two reactive oxidants, ferric-peroxo and ferryl-oxo (compound I) species, to participate in the conversion of androgens to estrogens. The ferric-peroxo species was determined, according to our derived mechanism, to act in the oxidation of 19-OH androgen to yield the 19,19-gem-diol intermediate and generate the ferryl-oxo (compound I) species. This species was then modeled to effect, in the final step, an abstraction of H from an O-H group of 19,19-gem-diol to give the experimentally observed products. We considered our new mechanistic scenario to reasonably explain the latest experimental observations and to provide deep insight complementing the newly accepted compound I (Cpd I) mechanism.

Computational study on palladium-catalyzed alkenylation of remote δ-C(sp3)-H bonds with alkynes: a new understanding of mechanistic insight and origins of site-selectivity.

Palladium-catalyzed alkenylation of δ-C(sp3)-H bonds with alkynes was conducted by density functional theory calculations. The present study shows that the dimeric Pd2(OAc)4 mechanism reproduces experimental observations well, including regioselectivity and provides a deep mechanistic insight complementing the monomeric Pd(OAc)2 mechanism recently reported by Chen's group. In addition, the economical heterodimeric Ni-Pd(OAc)4 was predicted to be a potential species for such alkenylation of δ-C(sp3)-H bonds.

Rhodomollins A and B, two Diterpenoids with an Unprecedented Backbone from the Fruits of Rhododendron molle.

Two new grayanoids, rhodomollin A (1) and rhodomollin B (2), possessing an unprecedented D-homo grayanane carbon skeleton, were isolated from the fruits of Rhododendron molle. The structures of 1 and 2 were fully characterized using a combination of spectroscopic analyses and X-ray crystallography. Rhodomollin B (2) exhibited modest activity against influenza virus A/95-359, with an IC50 value of 19.24 µM.

[Efficacy and safety of Choudongning capsule (CDN)in children with Tourette's syndrome of spleen deficiency and phlegm accumulation].

To evaluate the efficacy and safety of Choudongning (CDN)capsule in children with Tourette's syndrome of spleen deficiency and phlegm accumulation through a randomized double-blind three-arm controlled phase Ⅲ study in 588 patients from 8 hospitals. The included patients were randomly divided into test group, positive control group and placebo group at the ratio of 3∶1∶1. Patients in the test group orally took CDN capsules and simulated Tiapridal tablets; the patients in positive control group took Tiapridal tablets and simulated CDN capsules; whereas the patients in placebo group orally took the simulated agents of the above two drugs. The treatment course was 6 weeks for three groups. The global grading rates, YGTSS scores and its factor scores, the degree of social function damage, as well as traditional Chinese medicine syndrome efficacy were evaluated as the outcome measures on efficacy. The AEs/ADRs, vital signs and laboratory testing were observed as outcome measures on safety. The total effective rate of YGTSS was 75.92% in the test group, 72.65% in the positive control group, and 37.29% in the placebo group. Non inferiority test stands between the test group and the positive control group, and they were superior to placebo group in efficacy with statistical difference. Significant difference had also been found among the 3 groups in YGTSS tics score, motor tics score, vocal tics, degree of social function damage and traditional Chinese medicine syndrome efficacy. During the study, there were 5 (1.42%)ADRs in the test group, 10 (8.55%)in the positive control group and 3 (2.54%)in the placebo group. The incidence of ADRs in the test group was lower than that in the positive control group, with statistical difference. It is clear to say that CDN capsule can effectively treat the Tourette's syndrome of spleen deficiency and phlegm accumulation. Its efficacy is not inferior to the commonly used Tiapridal tablets, with even less adverse reactions, so it has clinical application value.

Qing Re Liang Xue Decoction Alleviates Hypercoagulability in Kawasaki Disease.

Objective. Kawasaki disease (KD) is a multisystemic autoimmune vasculitis. Intravenous immunoglobulin (IVIG) is the first-line treatment for KD. It is unclear whether traditional Chinese medicine (TCM) has an effect on KD. We aimed to observe the clinical efficacy of TCM on acute KD via serum interleukin-33 (IL-33) and tumor necrosis factor alpha (TNF-α) measurements. Methods. Thirty-one KD patients were treated with Qing Re Liang Xue decoction and Western medicine (integrative medicine treatment group), while 28 KD patients were treated with Western medicine only (Western medicine treatment group). Thirty patients were included in a febrile group and 28 healthy children were included in the control group. Clinical characteristics and laboratory findings were gathered and compared. Serum IL-33 and TNF-α levels were measured by multiplex Luminex assay. Results. The platelet count in the integrative medicine treatment group was significantly lower than that in the Western medicine treatment group. The integrative medicine group had a shorter fever duration and lower IL-33 and TNF-α levels than those in the Western medicine group, but there were no significant differences between the two KD groups after treatment. Conclusion. Qing Re Liang Xue decoction improved the hypercoagulable state of KD patients. Potential myocardial protective effects require further research.

Pitavastatin calcium improves endothelial function and delays the progress of atherosclerosis in patients with hypercholesterolemia.

BACKGROUND: Statins have proven efficacy in inhibiting the onset and progress of atherosclerosis. The effectiveness of pitavastatin in reversing carotid atherosclerosis associated with hypercholesterolemia (HC) is unknown. OBJECTIVES: To explore the simultaneous effects of pitavastatin calcium on brachial arterial flow-mediated vasodilatation (FMD), carotid intima-media thickness (IMT), and arterial stiffness (ß), three surrogate markers of atherosclerosis were studied in HC patients. METHODS: A randomized, double-blind trial was performed with 40 HC subjects who fulfilled the inclusion/exclusion criteria. Patients were given pitavastatin calcium 1 mg/d (Group 1) or 2 mg/d (Group 2) for 8 weeks. There were 20 patients in each group, and 30 gender- and age-matched healthy subjects as controls were recruited. FMD of the brachial artery, carotid IMT, and arterial stiffness indicated by ß were measured at baseline and at 8 weeks after starting pitavastatin calcium therapy using ultrasound techniques. Biochemical tests were also made on all subjects. RESULTS: At baseline, higher total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), reduced FMD, and increased ß and IMT were observed in HC patients (P<0.001 for all) compared with controls. After 8 weeks, TC was decreased by 20.59%/27.56% and LDL-C 30.92%/35.64%, respectively, in comparison to baseline groups; the HC groups had reduced ß and improved endothelial function over the 8-week follow-up (P<0.05-0.001); nonetheless, no significant alterations of IMT were found (P>0.05). Significant negative interactions between TC/LDL and FMD (P<0.05-0.001), positive interactions between TC and IMT (P=0.003) and between TC/LDL and ß (P<0.001-0.000) were found. CONCLUSIONS: Treatment with pitavastatin calcium exerted favorable effects on endothelial function and arterial stiffness. It also improved carotid atherosclerosis in patients with HC.

Hepatitis C virus structural proteins can exacerbate or ameliorate acetaminophen-induced liver injury in mice.

Chronic hepatitis C virus (HCV) infection predisposes patients to develop liver failure after acetaminophen (APAP) overdose. Mechanisms involved in this were explored using transgenic mice expressing the HCV structural proteins core, E1 and E2. Treatment of C57BL/6J mice with 200 mg/kg body weight APAP resulted in significant liver injury at 6 h as indicated by elevated ALT levels, focal centrilobular necrosis and nuclear DNA fragmentation. HCV transgenic mice showed a variable response, with approximately half the animals showing exacerbation of all parameters of liver injury, while the other half was protected. HCV transgenic mice with higher liver injury had lower liver glutathione levels, elevated mitochondrial oxidative stress and enhanced release of apoptosis-inducing factor (AIF) from the mitochondria. This was accompanied by induction of a higher ER stress response and induction of autophagy. Transgenic animals showing protection against liver injury had a robust recovery of liver glutathione content at 6 h when compared to wild-type animals, accompanied by reduction in mitochondrial oxidative stress and AIF release. This was accompanied by an elevation in glutathione S-transferase mRNA levels and activity, which suggests that an efficient clearance of the reactive intermediate may contribute to the protection against APAP hepatotoxicity in these mice. These results demonstrate that while HCV infection could exacerbate APAP-induced liver injury due to induction and amplification of mitochondrial oxidant stress, it could also protect against injury by activation of APAP scavenging mechanisms.

Osteopontin is an initial mediator of inflammation and liver injury during obstructive cholestasis after bile duct ligation in mice.

Osteopontin (OPN) is a chemotactic factor which can be cleaved to the pro-inflammatory form by matrix metalloproteinases (MMPs). To test the hypothesis that OPN can modulate inflammatory liver injury during cholestasis, wild-type (WT) C57BL/6 and OPN knockout (OPN-KO) mice underwent bile duct ligation (BDL). OPN-KO mice showed significant reduction in liver injury (plasma ALT and necrosis) and neutrophil recruitment compared with WT animals at 24h but not 72h after BDL. In WT mice, a 4-fold increase in hepatic MMP-3 mRNA and elevated MMP activities and cleaved OPN levels were observed in bile. WT mice subjected to BDL in the presence of the MMP inhibitor BB-94 showed reduced liver injury, less neutrophil extravasation and diminished levels of cleaved OPN in bile. Thus, during obstructive cholestasis, OPN released from biliary epithelial cells could be cleaved by MMPs in bile. When the biliary system leaks, cleaved OPN enters the parenchyma and attracts neutrophils. In the absence of OPN, other chemoattractants, e.g. chemokines, mediate a delayed inflammatory response and injury. Taken together, our data suggest that OPN is the pro-inflammatory mediator that initiates the early neutrophil-mediated injury phase during obstructive cholestasis in mice.

Blocking TLR2 activity diminishes and stabilizes advanced atherosclerotic lesions in apolipoprotein E-deficient mice.

AIM: Toll-like receptor 2 (TLR2) signaling plays a critical role in the initiation of atherosclerosis. The aim of this study was to investigate whether blocking TLR2 activity could produce therapeutic effects on advanced atherosclerosis. METHODS: Forty-week old apolipoprotein E-deficient (ApoE(-/-)) mice fed on a normal diet were intravenously injected with a TLR2-neutralizing antibody or with an isotype-matched IgG for 18 weeks. Double-knockout ApoE(-/-)Tlr2(-/-) mice were taken as a positive control. At the end of the treatments, the plasma lipid levels were measured, and the plaque morphology, pro-inflammatory cytokines expression and apoptosis in arteries were analyzed. In the second part of this study, 6-week old ApoE(-/-) and ApoE(-/-)Tlr2(-/-) mice fed on a high-cholesterol diet for 12 to 24 weeks, the expression levels of TLR2 and apoptotic markers in arteries were examined. RESULTS: Blockade of TLR2 activity with TLR2-neutralizing antibody or knockout of Tlr2 gene did not alter the plasma lipid levels in ApoE(-/-) mice. However, the pharmacologic and genetic manipulations significantly reduced the plaque size and vessel stenosis, and increased plaque stability in the brachiocephalic arteries. The protective effects of TLR2 antagonism were associated with the suppressed expression of pro-inflammatory cytokines IL-6 and TNF-α and the inactivation of transcription factors NF-κB and Stat3. In addition, blocking TLR2 activity attenuated ER stress-induced macrophage apoptosis in the brachiocephalic arteries, which could promote the resolution of necrotic cores in advanced atherosclerosis. Moreover, high-cholesterol diet more prominently accelerated atherosclerotic formation and increased the expression of pro-apoptotic protein CHOP and apoptosis in ApoE(-/-) mice than in ApoE(-/-)Tlr2(-/-) mice. CONCLUSION: The pharmacologic or genetic blockade of TLR2 activity diminishes and stabilizes advanced atherosclerotic lesions in ApoE(-/-) mice. Thus, targeting TLR2 signaling may be a promising therapeutic strategy against advanced atherosclerosis.