Electrical-Driven Directed-Evolution of Copper Nanowires Catalysts for Efficient Nitrate Reduction to Ammonia.

The electrocatalytic conversion of nitrate (NO3 - ) to NH3 (NO3 RR) at ambient conditions offers a promising alternative to the Haber-Bosch process. The pivotal factors in optimizing the proficient conversion of NO3 - into NH3 include enhancing the adsorption capabilities of the intermediates on the catalyst surface and expediting the hydrogenation steps. Herein, the Cu/Cu2 O/Pi NWs catalyst is designed based on the directed-evolution strategy to achieve an efficient reduction of NO3 ‾. Benefiting from the synergistic effect of the OV -enriched Cu2 O phase developed during the directed-evolution process and the pristine Cu phase, the catalyst exhibits improved adsorption performance for diverse NO3 RR intermediates. Additionally, the phosphate group anchored on the catalyst's surface during the directed-evolution process facilitates water electrolysis, thereby generating Hads on the catalyst surface and promoting the hydrogenation step of NO3 RR. As a result, the Cu/Cu2 O/Pi NWs catalyst shows an excellent FE for NH3 (96.6%) and super-high NH3 yield rate of 1.2 mol h-1  gcat. -1 in 1 m KOH and 0.1 m KNO3 solution at -0.5 V versus RHE. Moreover, the catalyst's stability is enhanced by the stabilizing influence of the phosphate group on the Cu2 O phase. This work highlights the promise of a directed-evolution approach in designing catalysts for NO3 RR.

Distributed Dynamic Event-Triggered Control to Leader-Following Consensus of Nonlinear Multi-Agent Systems with Directed Graphs.

This paper investigates achieving leader-following consensus in a class of multi-agent systems with nonlinear dynamics. Initially, it introduces a dynamic event-triggered strategy designed to effectively alleviate the strain on the system's communication resources. Subsequently, a distributed control strategy is proposed and implemented in the nonlinear leader-follower system using the dynamic event-triggered mechanism, aiming to ensure synchronization across all nodes at an exponential convergence speed. Thirdly, the research shows that under the dynamic event-triggered strategy the minimum event interval of any two consecutive triggers guarantees the elimination of Zeno behavior. Lastly, the validity of the calculation results is verified by a simulation example.

Metal-Stabilized Thiyl Radicals Design Inspired by Elemental Periodic Extension Notion for Ligand-Based Alkene Addition.

Inspired by alkene addition to the Ru and Re tris(thiolate) complexes via carbon-sulfur bond formation/cleavage reactions along with a periodic extension catalysis notion, a comparative study of the electronic structures, mechanisms, and reactivities for ethylene addition to the Os and Tc tris(thiolate) complexes was performed by DFT and high-level ab initio quantum calculations. The oxidized Os and Tc complexes were revealed to exhibit sufficient radical characters on the ligands to support their reaction with ethylene, whereas neutral Tc tris(thiolate) complex featuring little thiyl radical character renders no reactivity toward ethylene. Differential reactivities of these tris(thiolate) complexes was deemed to derive from the synergy of the thiyl radical character, the electronegativity, the row, and the charge. Extending from Ru and Re tris(thiolate) complexes to their Os and Tc counterparts can help us to get insightful rationales that would promote further research on alkene addition to metal-stabilized thiyl radicals.

Impact of body size on efficacy of high-dose dual therapy for Helicobacter pylori eradication.

BACKGROUND: High-dose dual therapy (HDDT) is an emerging and promising therapeutic regime for Helicobacter pylori (H. pylori) eradication. However, the pharmacokinetics of the components of HDDT, amoxicillin and proton pump inhibitor, are likely to be affected by body size. In this study, we aimed to find out the impact of body size on the efficacy of HDDT. METHODS: We collected the medical data of 385 treatment-naive patients infected with H. pylori who received HDDT (esomeprazole 20 mg and amoxicillin 750 mg four times daily) for 14 days from July 2020 to December 2021. The associations among the eradication efficacy, adverse events, and variables (sex, age, height, body weight, body mass index (BMI), body surface area (BSA), smoking, drinking, etc.) were analyzed respectively in our study. Among these factors, continuous variables were classified into categorical variables using the cut-off values which were calculated by receiver operating characteristic analysis. RESULTS: The eradication rate of HDDT was 89.9%. There were 55 (14.3%) patients who occurred adverse events during the treatment. Patients with height <170.5 cm, body weight <60.5 kg, BMI <20.55 kg/m2 , BSA <1.69 m2 had a higher eradication rate (92.1% vs. 84.0%, 93.1% vs. 86.8%, 96.0% vs. 87.8%, 93.4% vs. 84.8%, all p < .05). The multivariate analysis showed that BSA ≥1.69 m2 (OR 2.53, 95% CI: 1.28-4.99, p = .007) was the only independent predictor of eradication failure. CONCLUSION: HDDT could achieve better eradication efficacy in patients with small BSA. Clinicians should be aware of the impact of BSA on the H. pylori eradication rate and pay more attention to patients with large BSA.

Theoretical Understanding of Reactions of Rhenium and Ruthenium Tris(thiolate) Complexes with Unsaturated Hydrocarbons: Noninnocent Nature of the Ligand, Mechanism, and Origin of Differential Reactivity.

In retrospect to the complexity induced by the noninnocent ligands in identifying the transition metal's oxidation state and correlating the ligand's noninnocence with reactivity, the reactions of alkene/alkyne addition to rhenium/ruthenium tris(thiolate) complexes are particularly good cases for shedding light on the chemistry of the dppbt ligand, including its noninnocent nature, ligand-centered mechanism, and origin of differential reactivity. Density functional theory (DFT) combined with the high-level ab initio calculations performed herein demonstrates that, upon alkene/alkyne addition, the orbital symmetry properly regulates the reaction to form ligand-centered cis-interligand dithioethers as the most favorable pathway. The neutral and cationic Re and Ru dithioethers are revealed via DFT calculations to be in a low-spin ground state; on the contrary, high-level ab initio methods confirm that the dicationic Re-dithioethers exhibit obvious multireference character with antiferromagnetic coupling between Re-dyz and S1-py. The metal-stabilized thiyl radicals play a pivotal role in delivering the reactivity of [RuL3]+ and [ReL3]+/2+ toward alkene/alkyne rather than [ReL3], where [RuL3]+ and [ReL3]+/2+ present significant radical characters on ligand S2, yet neutral [ReL3] has little such feature, from which differential reactivity arises. Faster styrene addition to Ru tris(thiolate) in contrast to Re tris(thiolate) has been properly interpreted using DFT calculations with major products assigned. The deeper understanding gained in this work would illuminate further experimental exploration in adding alkene/alkyne to other metal-stabilized thiyl radicals.

Biosensor-based active ingredient recognition system for screening TNF-α inhibitors from lotus leaves.

Erhuangquzhi granules (EQG) have been clinically proven to be effective in nonalcoholic steatohepatitis (NASH) treatment. However, the active components and molecular mechanisms remain unknown. This study aimed to screen active components targeting tumor necrosis factor α (TNF-α) in EQG for the treatment of NASH by a surface plasmon resonance (SPR) biosensor-based active ingredient recognition system (SPR-AIRS). The amine-coupling method was used to immobilize recombinant TNF-α protein on an SPR chip, the specificity of the TNF-α-immobilized chip was validated, and nine medicinal herbs in EQG were prescreened. Nuciferine (NF), lirinidine (ID), and O-nornuciferine (NNF) from lotus leaves were found and identified as TNF-α ligands by UPLC‒MS/MS, and the affinity constants of NF, ID, and NNF to TNF-α were determined by SPR experiments (Kd = 61.19, 31.02, and 20.71 µM, respectively). NF, ID, and NNF inhibited TNF-α-induced apoptosis in L929 cells, the levels of secreted IL-6 and IL-1ß were reduced, and the phosphorylation of IKKß and IκB was inhibited in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. In conclusion, a class of new active small-molecule TNF-α inhibitors was discovered, which also provides a valuable reference for the material basis and mechanism of EQG action in NASH treatment.

[Establishment of a fast discriminant model with electronic nose for Polygonati Rhizoma mildew based on odor variation].

The odor fingerprint of Pollygonati Rhizoma samples with different mildewing degrees was analyzed and the relationship between the odor variation and the mildewing degree was explored. A fast discriminant model was established according to the response intensity of electronic nose. The α-FOX3000 electronic nose was applied to analyze the odor fingerprint of Pollygonati Rhizoma samples with different mildewing degrees and the radar map was used to analyze the main contributors among the volatile organic compounds. The feature data were processed and analyzed by partial least squares discriminant analysis(PLS-DA), K-nearest neighbor(KNN), sequential minimal optimization(SMO), random forest(RF) and naive Bayes(NB), respectively. According to the radar map of the electronic nose, the response values of three sensors, namely T70/2, T30/1, and P10/2, increased with the mildewing, indicating that the Pollygonati Rhizoma produced alkanes and aromatic compounds after the mildewing. According to PLS-DA model, Pollygonati Rhizoma samples of three mildewing degrees could be well distinguished in three areas. Afterwards, the variable importance analysis of the sensors was carried out and then five sensors that contributed a lot to the classification were screened out: T70/2, T30/1, PA/2, P10/1 and P40/1. The classification accuracy of all the four models(KNN, SMO, RF, and NB) was above 90%, and KNN was most accurate(accuracy: 97.2%). Different volatile organic compounds were produced after the mildewing of Pollygonati Rhizoma, and they could be detected by electronic nose, which laid a foundation for the establishment of a rapid discrimination model for mildewed Pollygonati Rhizoma. This paper shed lights on further research on change pattern and quick detection of volatile organic compounds in moldy Chinese herbal medicines.

Machine-learning model derived gene signature predictive of paclitaxel survival benefit in gastric cancer: results from the randomised phase III SAMIT trial.

OBJECTIVE: To date, there are no predictive biomarkers to guide selection of patients with gastric cancer (GC) who benefit from paclitaxel. Stomach cancer Adjuvant Multi-Institutional group Trial (SAMIT) was a 2×2 factorial randomised phase III study in which patients with GC were randomised to Pac-S-1 (paclitaxel +S-1), Pac-UFT (paclitaxel +UFT), S-1 alone or UFT alone after curative surgery. DESIGN: The primary objective of this study was to identify a gene signature that predicts survival benefit from paclitaxel chemotherapy in GC patients. SAMIT GC samples were profiled using a customised 476 gene NanoString panel. A random forest machine-learning model was applied on the NanoString profiles to develop a gene signature. An independent cohort of metastatic patients with GC treated with paclitaxel and ramucirumab (Pac-Ram) served as an external validation cohort. RESULTS: From the SAMIT trial 499 samples were analysed in this study. From the Pac-S-1 training cohort, the random forest model generated a 19-gene signature assigning patients to two groups: Pac-Sensitive and Pac-Resistant. In the Pac-UFT validation cohort, Pac-Sensitive patients exhibited a significant improvement in disease free survival (DFS): 3-year DFS 66% vs 40% (HR 0.44, p=0.0029). There was no survival difference between Pac-Sensitive and Pac-Resistant in the UFT or S-1 alone arms, test of interaction p<0.001. In the external Pac-Ram validation cohort, the signature predicted benefit for Pac-Sensitive (median PFS 147 days vs 112 days, HR 0.48, p=0.022). CONCLUSION: Using machine-learning techniques on one of the largest GC trials (SAMIT), we identify a gene signature representing the first predictive biomarker for paclitaxel benefit. TRIAL REGISTRATION NUMBER: UMIN Clinical Trials Registry: C000000082 (SAMIT); ClinicalTrials.gov identifier, 02628951 (South Korean trial).

Bromodomain-containing protein 9 promotes hepatocellular carcinoma progression via activating the Wnt/ß-catenin signaling pathway.

BACKGROUND: Epigenetic dysregulation participates in the initiation and progression of hepatocellular carcinoma (HCC). Bromodomain-containing protein 9 (BRD9) can identify acetylated lysine residues, contributing to several cancers. The function and molecular mechanism of BRD9 in HCC remain poorly understood. METHODS: BRD9 levels in tissues and cells of HCC and normal liver were evaluated using bioinformatic analysis, real-time PCR, and western blot. BRD9's association with clinical outcomes was investigated via survival analyses. Biological behaviors and pathways related to BRD9 were predicted using gene set enrichment analysis. BRD9's role in proliferation was verified via cell counting kit 8, colony formation, and 5-Ethynyl-2'-deoxyuridine assays. Its role in the cell cycle and apoptosis was assessed using flow cytometry. The role of BRD9 in vivo was investigated using xenograft tumor models. A rescue assay was performed to investigate the molecular mechanism of BRD9. RESULTS: BRD9 was markedly upregulated in HCC and higher BRD9 expression was associated with higher grade, advanced stage, greater tumor size, and poorer prognosis. BRD9 overexpression enhanced cell proliferation, cell cycle progress, but impeded cell apoptosis. BRD9 downregulation had the opposite effects. In vivo, BRD9 promoted xenograft tumor growth. Mechanistically, BRD9 activated Wnt/ß-catenin signaling, obstruction of which abrogated BRD9-mediated tumorigenesis. CONCLUSION: Increased BRD9 in HCC correlated with poor prognosis, which functioned via activating Wnt/ß-catenin signaling. Thus, BRD9 might be a promising biomarker and therapeutic target for patients with HCC.

In Silico Repurposed Drugs against Monkeypox Virus.

Monkeypox is an emerging epidemic of concern. The disease is caused by the monkeypox virus and an increasing global incidence with a 2022 outbreak that has spread to Europe amid the COVID-19 pandemic. The new outbreak is associated with novel, previously undiscovered mutations and variants. Currently, the US Food and Drug Administration (FDA) approved poxvirus treatment involves the use of tecovirimat. However, there is otherwise limited pharmacopoeia and research interest in monkeypox. In this study, virtual screening and molecular dynamics were employed to explore the potential repurposing of multiple drugs previously approved by the FDA or other jurisdictions for other applications. Several drugs are predicted to tightly bind to viral proteins, which are crucial in viral replication, including molecules which show high potential for binding the monkeypox D13L capsid protein, whose inhibition has previously been demonstrated to suppress viral replication.

A novel prognostic index of hepatocellular carcinoma based on immunogenomic landscape analysis.

Changes in immune responses to hepatocellular carcinoma (HCC) are closely related to the occurrence, development, and prognosis of this disease. Exploring the role of immune-related genes (IRGs) in HCC would provide insights into the mechanisms regulating this disease. The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) provide a platform for such research, owing to a large number of HCC samples available for comprehensive and systematic immunogenomics analyses. We analyzed the IRGs expression profile and clinical information of patients with HCC based on the TCGA and ICGC database. Potential molecular mechanisms and properties of the screened IRGs were analyzed across multiple databases. And we analyzed the correlation between IRGs, single-nucleotide polymorphisms, and copy number variation. A novel prognostic index, based on IRGs, was developed using the LASSO Cox regression algorithm, followed by univariate and multivariate Cox regression analyses to analyze the prognostic index. Information in the ICGC database was used to verify the reliability of the prognostic index. A total of 54 differentially expressed IRGs were found to be significantly associated with HCC prognosis, and there is a significant correlation between their expression level and copy number variation. Functional enrichment analyses indicated that the genes play active roles in tumor and immune-related signaling pathways. In addition, five potential biomarkers namely IRG, MAPK3, HSP90AA1, HSP90AB1, HSPA4, and CDK4, were identified. Finally, a novel prognostic index, based on IRGs (PSMD14, FABP6, ISG20L2, HGF, BIRC5, IL17D, and STC2), was found useful as an independent prognostic factor, not only for prognosis but also to reflect levels of infiltration in a variety of immune cells. Our team conducted a genomics study of IRGs in HCC and screened several clinically significant IRGs, and our model provides an effective approach for stratification and characterization of patients using IRG-based immunolabeling tools to monitor the prognosis of HCC.

The expression profiles and prognostic values of HSP70s in hepatocellular carcinoma.

BACKGROUND: The HSP70 family of heat shock protein plays a critical role in protein synthesis and transport to maintain protein homeostasis. Several studies have indicated that HSP70s are related to the development and occurrence of various cancers. METHODS: The relationship between the overall survival rate of hepatocellular carcinoma patients and the expression of 14 HSP70s from multiple databases, such as TCGA, ONCOMINE, cBioPortal was investigated. Western Blot and PCR were used to evaluate HSPA4 and HSPA14 expressions in various HCC cells to identify suitable cell lines for further experiments .Wound-healing assays, Transwell assays and EdU assays were used to verify the effects of HSPA4 and HSPA14 on the function of hepatocellular carcinoma cells, and statistical analysis was performed. RESULTS: Hepatocellular carcinoma tissues significantly expressed the 14 HSP70s compared to the normal samples. Besides, the high HSPA1A, HSPA1B, HSPA4, HSPA5, HSPA8, HSPA13, and HSPA14 expressions were inversely associated with the overall survival rate of patients, tumor grade, and cancer stage. A PPI regulatory network was constructed using the 14 HSP70s proteins with HSPA5 and HSPA8 at the network center. Univariate and multivariate analyses showed that HSPA4 and HSPA14 could be independent risk factors for the prognosis of hepatocellular carcinoma patients. Cell experiments have also confirmed that reducing HSPA4 and HSPA14 expressions can inhibit the invasion, metastasis, and proliferation of hepatocellular carcinoma cells. CONCLUSIONS: Therefore, the HSP70s significantly influence the occurrence and development of hepatocellular carcinoma. For instance, HSPA4 and HSPA14 can be novel therapeutic targets and prognostic biomarkers for hepatocellular carcinoma.

Clinical biomarkers in adjuvant chemotherapy for gastric cancer after D2 dissection by a pooled analysis of individual patient data from large randomized controlled trials.

BACKGROUND: Adjuvant therapy for gastric cancer is a standard among the world with no regimen selection criteria. Also, prognostic factors except for tumor staging have not been established. We aimed to identify prognostic and predictive markers for gastric cancer adjuvant therapy from large randomized controlled trials with standard lymph node dissection. METHODS: Three studies: ACTS-GC, CLASSIC, and SAMIT were found and selected for a pooled analysis, following PRISMA guideline. The integrity of individual participant data (IPD) was verified in the eligible 3527 patients registered, and fixed-effect model was used. The primary endpoint was relapse-free survival (RFS) and the secondary endpoint was overall survival (OS). RESULTS: Age was a significant prognostic factor in addition to tumor stages both in "surgery alone" and "adjuvant" groups. Adjuvant therapy was effective for every TN stage; however, it tended to be more effective in T1-2 than in T3-4. Also, it was more effective in low- or middle-BMI than in high-BMI group with Hazard ratio [HR]s: 0.58, 0.58, and 1.05, respectively. Capecitabine plus oxaliplatin (CAPOX) was more effective than S-1 for T1-2, N2-3, and differentiated type with HRs between 0.59 and 0.70, but with no difference among TNM stages. Combining histology to TN; the HRs in differentiated T1-2 N1-3 groups were between 0.29 and 0.45. For T3-4 N0-1 group, S-1 was likely to be effective, not significant. CONCLUSIONS: Age is a significant prognostic factor both in surgery alone and adjuvant group. CAPOX is more effective for differentiated T1-2 tumors with lymph node metastasis.

Association between serum HER2/ErbB2 levels and coronary artery disease: a case-control study.

BACKGROUND: Research has associated human epidermal growth factor receptor (HER2) with glucose and lipid metabolism. However, the association between circulating HER2 levels and coronary artery disease (CAD) remains to be elucidated. METHODS: We performed a case-control study with 435 participants (237 CAD patients and 198 controls) who underwent diagnostic coronary angiography from September 2018 to October 2019. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for CAD were calculated with multiple logistic regression models after adjustment for confounders. RESULTS: Overall, increased serum HER2 levels were independently associated with the presence of CAD (OR per 1-standard deviation (SD) increase: 1.438, 95% CI 1.13-1.83; P = 0.003) and the number of stenotic vessels (OR per 1-SD increase: 1.399, 95% CI 1.15-1.71; P = 0.001). In the subgroup analysis, a significant interaction of HER2 with body mass index (BMI) on the presence of CAD was observed (adjusted interaction P = 0.046). Increased serum HER2 levels were strongly associated with the presence of CAD in participants with BMI ≥ 25 kg/m2 (OR per 1-SD increase: 2.143, 95% CI 1.37-3.35; P = 0.001), whereas no significant association was found in participants with BMI < 25 kg/m2 (OR per 1-SD increase: 1.225, 95% CI 0.90-1.67; P = 0.201). CONCLUSION: Elevated HER2 level is associated with an increased risk of CAD, particularly in people with obesity. This finding yields new insight into the pathological mechanisms underlying CAD, and warrants further research regarding HER2 as a preventive and therapeutic target of CAD.

Long non-coding RNA LINC01503 promotes the progression of hepatocellular carcinoma via activating MAPK/ERK pathway.

Background: Increasing evidence has implicated that lncRNAs (long non-coding RNAs) play significant roles in carcinogenesis and progression of HCC (hepatocellular carcinoma). LINC01503 is a new lncRNA related to several tumors. Nonetheless, its role in HCC still remains unclear. Methods: The expression levels of LINC01503 in HCC, normal liver tissues as well as HCC cell lines were evaluated by TCGA (The Cancer Genome Atlas) and real-time PCR assay, respectively. The relationship between LINC01503 levels and the prognosis of patients with HCC was evaluated using Kaplan-Meier survival analysis. Then the potential biological functions and pathways related to LINC01503 were investigated by GO (Gene Ontology) analysis and KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis, and GSEA v4.0.1 software was employed. Furthermore, the influence of LINC01503 on the proliferation and apoptosis of HCC cells was confirmed using CCK8 assay, flow cytometry, and clone formation assay in cell experiments. Also the pro-tumor effect of LINC01503 was verified by mice xenograft experiment in vivo. In addition, the functional pathway of LINC01503 was proved by western blot and rescue experiments. Results: LINC01503 was highly expressed in HCC and positively correlated with large tumor size, high tumor grade, advanced tumor stage, and poor prognosis of HCC patients. Silencing LINC01503 with shRNA significantly restrained the proliferation of MHCC-97H HCC cells and strengthened the apoptosis, while up-regulation of LINC01503 in Huh7 HCC cells contributed to the contrary effects. Besides, LINC01503 promoted tumor growth of nude mice transplanted with liver cancer cells. Mechanistically, MAPK/ERK signaling pathway was activated by LINC01503, inhibition of which could alleviate the pro-tumor effect of LINC01503, consistent with the forecast of GSEA (Gene Set Enrichment Analysis). Conclusion: LINC01503 is highly expressed in HCC and promotes the progression of HCC via MAPK/ERK pathway, which maybe a new potential biomarker and therapeutic target for HCC.

[Identification of Curcuma herbs using XGBoost algorithm in electronic nose odor fingerprint].

This article aims to identify four commonly applied herbs from Curcuma genus of Zingiberaceae family,namely Curcumae Radix( Yujin),Curcumae Rhizoma( Ezhu),Curcumae Longae Rhizoma( Jianghuang) and Wenyujin Rhizoma Concisum( Pianjianghuang). The odor fingerprints of those four herbal medicines were collected by electronic nose,respectively. Meanwhile,XGBoost algorithm was introduced to data analysis and discriminant model establishment,with four indexes for performance evaluation,including accuracy,precision,recall,and F-measure. The discriminant model was established by XGBoost with positive rate of returning to 166 samples in the training set and 69 samples in the test set were 99. 39% and 95. 65%,respectively. The top four of the contribution to the discriminant model were LY2/g CT,P40/1,LY2/Gh and LY2/LG,the least contributing sensor was T70/2. Compared with support vector machine,random forest and artificial neural network,XGBoost algorithms shows better identification capacity with higher recognition efficiency. The accuracy,precision,recall and F-measure of the XGBoost discriminant model forecast set were 95. 65%,95. 25%,93. 07%,93. 75%,respectively. The superiority of XGBoost in the identification of Curcuma herbs was verified. Obviously,this new method could not only be suitable for digitization and objectification of traditional Chinese medicine( TCM) odor indicators,but also achieve the identification of different TCM based on their odor fingerprint in electronic nose system. The introduction of XGBoost algorithm and more excellent algorithms provide more ideas for the application of electronic nose in data mining for TCM studies.

Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tp'Rh(CNR)(carbodiimide): A Computational and Time-Resolved Infrared Spectroscopic Study.

Carbon-hydrogen bond activation of alkanes by Tp'Rh(CNR) (Tp' = Tp = trispyrazolylborate or Tp* = tris(3,5-dimethylpyrazolyl)borate) were followed by time-resolved infrared spectroscopy (TRIR) in the υ(CNR) and υ(B-H) spectral regions on Tp*Rh(CNCH2CMe3), and their reaction mechanisms were modeled by density functional theory (DFT) on TpRh(CNMe). The major intermediate species were: κ3-η1-alkane complex (1); κ2-η2-alkane complex (2); and κ3-alkyl hydride (3). Calculations predict that the barrier between 1 and 2 arises from a triplet-singlet crossing and intermediate 2 proceeds over the rate-determining C-H activation barrier to give the final product 3. The activation lifetimes measured for the Tp*Rh(CNR) and Tp*Rh(CO) fragments with n-heptane and four cycloalkanes (C5H10, C6H12, C7H14, and C8H16) increase with alkanes size and show a dramatic increase between C6H12 and C7H14. A similar step-like behavior was observed previously with CpRh(CO) and Cp*Rh(CO) fragments and is attributed to the wider difference in C-H bonds that appear at C7H14. However, Tp'Rh(CNR) and Tp'Rh(CO) fragments have much longer absolute lifetimes compared to those of CpRh(CO) and Cp*Rh(CO) fragments, because the reduced electron density in dechelated κ2-η2-alkane Tp' complexes stabilizes the d8 Rh(I) in a square-planar geometry and weakens the metal's ability for oxidative addition of the C-H bond. Further, the Tp'Rh(CNR) fragment has significantly slower rates of C-H activation in comparison to the Tp'Rh(CO) fragment for the larger cycloalkanes, because the steric bulk of the neopentyl isocyanide ligand hinders the rechelation in κ2-Tp'Rh(CNR)(cycloalkane) species and results in the C-H activation without the assistance of the rechelation.

[Effects of nitrogen and sulfur combined application on nutritional components and active components of Isatis indigotica at seedling stage].

Using split plot design, a pot experiment with sand culture was conducted to investigate the effects ofnitrogen and sulfur combined application on nutritional components and active component of Isatis indigotica at seedling stage under different N (5，15，25 mmol·L⁻¹)and S(0.00，1.25，2.50，5.00，7.50 mmol·L⁻¹) levels. The results showed thatthe two elements had obvious effects and the leaf and root dry weights of I. indigotica seedlings increased greatly at N2 level. Under the same nitrogen concentration, the leaf and root dry weights increased firstly and decreased with the rising of sulfur concentrations in which S2 was conducive to the growth and biomass accumulation. Soluble sugar, soluble protein, soluble amino acids contents were the highest in N1, N2 and N3 treatments, respectively. The influence of sulfur concentrations on nutritional components was same as biomass, but the peak of different nutritional components was diversity in different nitrogen levels. The effects on secondary metabolites (total flavones, indigo, indriubin, epigotrin contents) were not obvious significantly, in which these indexes by N1S3，N1S2，N3S0，N3S1were the highest, respectively. In conclusion, the combination of nitrogen and sulfur of N2S2(N 15 mmol·L⁻¹ and S 2.5 mmol·L⁻¹) was beneficial to the growth and secondary metabolites accumulation of I. indigotica. These results could provide a theoretical basis for rational fertilization and cultivation of I. indigotica seedling.

Nickel Fluorocarbene Metathesis with Fluoroalkenes.

Alkene metathesis with directly fluorinated alkenes is challenging, limiting its application in the burgeoning field of fluoro-organic chemistry. A new nickel tris(phosphite) fluoro(trifluoromethyl)carbene complex ([P3 Ni]=CFCF3 ) reacts with CF2 =CF2 (TFE) or CF2 =CH2 (VDF) to yield both metallacyclobutane and perfluorocarbene metathesis products, [P3 Ni]=CF2 and CR2 =CFCF3 (R=F, H). The reaction of [P3 Ni]=CFCF3 with trifluoroethylene also yields metathesis products, [P3 Ni]=CF2 and cis/trans-CFCF3 =CFH. However, unlike reactions with TFE and VDF, this reaction forms metallacyclopropanes and fluoronickel alkenyl species, resulting presumably from instability of the expected metallacyclobutanes. DFT calculations and experimental evidence established that the observed metallacyclobutanes are not intermediates in the formation of the observed metathesis products, thus highlighting a novel variant of the Chauvin mechanism enabled by the disparate four-coordinate transition states.

Solid-State NMR H-N-(C)-H and H-N-C-C 3D/4D Correlation Experiments for Resonance Assignment of Large Proteins.

Solid-state NMR spectroscopy can provide insight into protein structure and dynamics at the atomic level without inherent protein size limitations. However, a major hurdle to studying large proteins by solid-state NMR spectroscopy is related to spectral complexity and resonance overlap, which increase with molecular weight and severely hamper the assignment process. Here the use of two sets of experiments is shown to expand the tool kit of 1 H-detected assignment approaches, which correlate a given amide pair either to the two adjacent CO-CA pairs (4D hCOCANH/hCOCAcoNH), or to the amide 1 H of the neighboring residue (3D HcocaNH/HcacoNH, which can be extended to 5D). The experiments are based on efficient coherence transfers between backbone atoms using INEPT transfers between carbons and cross-polarization for heteronuclear transfers. The utility of these experiments is exemplified with application to assemblies of deuterated, fully amide-protonated proteins from approximately 20 to 60 kDa monomer, at magic-angle spinning (MAS) frequencies from approximately 40 to 55 kHz. These experiments will also be applicable to protonated proteins at higher MAS frequencies. The resonance assignment of a domain within the 50.4 kDa bacteriophage T5 tube protein pb6 is reported, and this is compared to NMR assignments of the isolated domain in solution. This comparison reveals contacts of this domain to the core of the polymeric tail tube assembly.