Bromine-mediated strategy endows efficient electrochemical oxidation of amine to nitrile.

Conventional methods for nitrile synthesis bring inherent environmental risks due to their reliance on oxidants and harsh reaction conditions. Meanwhile, direct electrooxidation of amines to nitriles suffers from low current density. In this study, we propose an innovative indirect electrooxidation strategy for nitrile formation, mediated by Br-/Br2, utilizing a highly efficient CoS2/CoS@Graphite Felt (GF) electrode. Notably, the anodic nitrile generation can be synergistically coupled with the cathodic hydrogen evolution reaction (HER). Through meticulous optimization of reaction parameters, we achieve an impressive 98% selectivity for octanenitrile at a current density of 60 mA cm-2 with a remarkable faradaic efficiency (FE) of 87%. Furthermore, our approach demonstrates excellent versatility, as we successfully evaluate both aliphatic and aromatic primary amines, highlighting its promising potential for practical applications in the field.

Exosomes Derived from Quercetin-Treated Bone Marrow Derived Mesenchymal Stem Cells Inhibit the Progression of Osteoarthritis Through Delivering miR-124-3p to Chondrocytes.

Osteoarthritis (OA) is a chronic disease characterized by the progressive loss of cartilage and failure of the diarrheal joint. Quercetin has been reported to attenuate the development of OA. Bone marrow derived mesenchymal stem cell (BMSC)-derived exosomes are involved in OA progression. However, the role of BMSC-derived exosomes in quercetin-mediated progression of OA remains unclear. Western blotting and RT-qPCR were used to assess protein and mRNA levels, respectively. CCK8 assay was performed to assess cell viability, and cell apoptosis was assessed using flow cytometry. A dual-luciferase assay was performed to assess the relationship between miR-124-3p and TRAF6 expression. Furthermore, in vivo experiments were performed to test the function of exosomes derived from Quercetin-treated BMSCs in OA patients. IL-1ß significantly inhibited the viability of chondrocytes, whereas the conditioned medium of Quercetin-treated BMSCs (BMSCsQUE-CM) reversed this phenomenon through exosomes. IL-1ß notably upregulated MMP13 and ADAMT5 and reduced the expression of COL2A1 in chondrocytes, which were rescued by BMSCsQUE-CM. The effects of BMSCsQUE-CM on these three proteins were reversed in the absence of exosomes. Exosomes can be transferred from BMSCs to chondrocytes, and exosomes derived from Quercetin-treated BMSCs (BMSCsQue-Exo) can reverse the apoptotic effects of IL-1ß on chondrocytes. The level of miR-124-3p in BMSCs was significantly upregulated by quercetin, and miR-124-3p was enriched in BMSCsQue-Exo. TRAF6 was identified as a direct target of miR-124-3p, and BMSCsQue-Exo abolished the IL-1ß-induced activation of MAPK/p38 and NF-κB signaling. Furthermore, BMSCsQue-Exo significantly attenuated OA progression in vivo. Exosomes derived from Quercetin-treated BMSCs inhibited OA progression through the upregulation of miR-124-3p.

[A retrospective study on manual reduction combined with Chinese Orthopaedic ankle external fixator in the treatment of trimalleolar fracture].

OBJECTIVE: To evaluate the needle puncture safety and clinical efficacy of manual reduction combined with external fixation of ankle frame in the treatment of trimalleolar fracture under the guidance of Chinese Osteosynthesis (CO) theory. METHODS: The clinical data of 118 patients with trimalleolar fractures admitted from December 2010 to December 2021 were retrospectively analyzed. Fifty-three patients were treated with manual reduction combined with external fixation of ankle frame(observation group). Sixty-five patients were treated with open reduction and internal fixation with plate and screws(control group). The operation time, hospitalization days, non-weight-bearing time of the affected limb, clinical healing time of fracture, incidence of complications, visual analogue scale (VAS) before and 1 month after operation, and American Orthopedic Foot and Ankle Society(AOFAS) score of ankle joint before and 1 year after operation were compared between the two groups. RESULTS: Patients in both groups were followed up for more than 1 year. All patients were followed up, and the duration ranged from 14 to 70 months, with an average of(35.28±14.66) months. There were statistically significant in operation time, hospitalization days, non-load-bearing time of affected limbs, clinical healing time of fractures and VAS score one month after operation between the two groups. One month after operation, the VAS score of the observation group was lower than that of the control group(t=3.343, P=0.001). The operation time of the observation group was significantly shorter than that of the control group(t=9.091, P=0.000). The hospitalization days in the observation group were significantly less than those in the control group(t=5.034, P=0.000). The non-load-bearing time of the affected limb in the observation group was significantly shorter than that in the control group(t=11.960, P=0.000). The clinical healing time of fracture in the observation group was significantly shorter than that in the control group(t=4.007, P=0.000). There was no significant difference in AOFAS score between the two groups one year after operation(t=0.417, P=0.678). In the observation group, there were 2 cases of pinhole infection and 3 cases of loss of reduction less than 2 mm. There were 3 cases of surgical incision infection in the control group. There was no significant difference in the incidence of complications between the two groups(χ2=0.446, P=0.504). CONCLUSION: Manual reduction combined with external fixation is safe and effective in the treatment of trimalleolar fracture under the guidance of CO theory, and the function of ankle joint recovers well after operation. This therapy has good clinical value.

Phase-Selective Synthesis of Cobalt Sulfide Heterostructure Catalysts as Efficient Counter Electrodes in Dye-Sensitized Solar Cells.

Developing a cost-saving, high-efficiency, and simple synthesis of counter electrode (CE) material to replace pricy Pt for dye-sensitized solar cells (DSSCs) has become a research hotspot. Owing to the electronic coupling effects between various components, semiconductor heterostructures can significantly enhance the catalytic performance and endurance of counter electrodes. However, the strategy to controllably synthesize the same element in several phase heterostructures used as the CE in DSSCs is still absent. Here, we fabricate well-defined CoS2 /CoS heterostructures and use them as CE catalysts in DSSCs. The as-designed CoS2 /CoS heterostructures display high catalytic performance and endurance for the triiodide reduction in DSSCs thanks to the combined and synergistic effects. As a result, a DSSC with CoS2 /CoS achieves a high energy conversion with an efficiency of 9.47 % under standard simulated solar radiation, surpassing that of pristine Pt-based CE (9.20 %). Besides, the CoS2 /CoS heterostructures possess a quick activity initiation process and extended stability, broadening their potential applications in various areas. Therefore, our proposed synthetic approach could offer new insights for synthesizing functional heterostructure materials with improved catalytic activities in DSSCs.

Manual Reduction and Plaster External Fixation for the Treatment of Closed Total Talus Dislocation: Case Report and Literature Review.

BACKGROUND: Total dislocation of the talus from all its surrounding joints (talonavicular, tibiotalar, subtalar) is one kind of serious injury of the lower extremity with rare occurrence. It is usually accompanied by fractures of the talus and its periphery, as well as severe soft tissue injury, which is difficult to reset. Complications such as skin necrosis and infection are prone to occur in the early stage, and talus necrosis are prone to occur in the late stage, all of which aggravate disease severity and increase difficulties for its treatment. CASE PRESENTATION: Herein, we reported a case of right talus total dislocation accompanied by medial malleolus fracture and posterior tubercle fracture caused by traffic accident. One hour after injury, the doctor tried to perform manual reduction but failed. Then, we successfully performed manual reduction and plaster external fixation on this patient under anesthesia 6 h after injury, followed by the oral administration of Chinese medicine for 3 months. Twenty months of follow-up investigations revealed that no skin necrosis, talus dislocation, talus necrosis, or other complications occurred; no obvious joint degeneration was observed and the fractures of medial malleolus and talus healed well. MRI of ankle joint indicated the disappearance of ankle effusion caused by injury, and the bone marrow edema had also subsided at talus, medial malleolus, and lateral malleolus and calcaneus. Patient presented with no ligament relaxation, ankle instability, pain, swelling, or functional limitation of the injured limb. AOFAS score reached 100. Daily functions and recreation activities were recovered back to the normal level. CONCLUSION: For patients with closed total dislocation of the talus, fine therapeutic effects can be achieved by early closed manual reduction and plaster external fixation under anesthesia, in combination with oral Chinese herbal medicine afterwards. It is worthy of reference for clinicians.

Metal-Free Phosphination and Continued Functionalization of Pyridine: A Theoretical Study.

This study investigates the mechanism of metal-free pyridine phosphination with P(OEt)3, PPh3, and PAr2CF3 using density functional theory calculations. The results show that the reaction mechanism and rate-determining step vary depending on the phosphine and additive used. For example, phosphination of pyridine with P(OEt)3 occurs in five stages, and ethyl abstraction is the rate-determining step. Meanwhile, 2-Ph-pyridine phosphination with PPh3 is a four-step reaction with proton abstraction as the rate-limiting step. Energy decomposition analysis of the transition states reveals that steric hindrance in the phosphine molecule plays a key role in the site-selective formation of the phosphonium salt. The mechanism of 2-Ph-pyridine phosphination with PAr2CF3 is similar to that with PPh3, and analyses of the effects of substituents show that electron-withdrawing groups decreased the nucleophilicity of the phosphine, whereas aryl electron-donating groups increased it. Finally, TfO- plays an important role in the C-H fluoroalkylation of pyridine, as it brings weak interactions.

A Cross-Sectional Study of Individual Learning Passion in Medical Education: Understanding Self-Development in Positive Psychology.

Background: Boosting the individual learning passion of medical students is a novel approach to improve their academic performance. It facilitates the medical education reform, motivating both policymakers and educators to focus on the function of positive psychology in the career development of medical students. Therefore, this study aimed (1) to assess the status of two types of learning passion; (2) to clarify the relationship between self-esteem and two types of learning passion among Chinese medical students; (3) to examine the mediating role of psychological capital (PsyCap) in the relationship between self-esteem and two types of learning passion, respectively; and (4) to identify the moderating role of professional identity in the relationship between PsyCap and two types of learning passion, respectively. Methods: A cross-sectional online survey was conducted from April to June 2016 in China. A total of 1,218 valid questionnaires (effective completion rate: 67.93%) were collected from four medical schools. Results: Self-esteem significantly and positively influenced medical students' PsyCap (ß = 0.637, P < 0.01) and two types of learning passion, including harmonious learning passion (ß = 0.589, P < 0.01) and obsessive learning passion (ß = 0.436, P < 0.01). PsyCap fully mediated the relationship (ß = 0.578, P < 0.01) between self-esteem and harmonious learning passion positively, whereas it suppressed the relationship (ß = 0.490, P < 0.01) between self-esteem and obsessive learning passion. Further, professional identity significantly moderated the correlation between PsyCap and harmonious learning passion (ß = -0.554, P < 0.05), rather than obsessive learning passion (P > 0.05). Conclusion: Two types of learning passion of medical students are positively influenced by self-esteem and PsyCap. Medical students with high-level self-esteem should possess strong PsyCap, which augments their harmonious as well as obsessive learning passion. Moreover, the positive effect of medical students' PsyCap on harmonious learning passion is more notable among those with a lower professional identity. Finally, this study argues that strengths-based interventions of self-esteem and PsyCap are a beneficial approach for future enhancing learning passion in the domain of medical education.

A Theoretical Study on the Borane-Catalyzed Reductive Amination of Aniline and Benzaldehyde with Dihydrogen: The Origins of Chemoselectivity.

Density functional theory calculations are used in this study to investigate the product selectivity and mechanism of borane-catalyzed reductive aldehyde amination by a H2 reducing agent. Knowing that different boranes yield different products, two typical boranes, (B(2,6-Cl2C6H3)(p-HC6F4)2 and B(C6F5)3), are studied. Of the seven possible pathways of B(2,6-Cl2C6H3)(p-HC6F4)2-catalyzed aldehyde amination analyzed herein, four are favorable. Three of the four favorable pathways involve imine intermediates, and the fourth is a Lewis acid-base synergistic pathway that involves amine-alcohol condensation. As for the B(C6F5)3 catalyst, it forms a highly stable Lewis adduct with aniline, which impedes the hydrogenation of imine. Therefore, the product of B(C6F5)3-catalyzed reductive amination of benzaldehyde and aniline is an imine. The linear relationship between the charge on the boron atom in the Lewis acid and the relative energies of the Lewis adduct and H2 splitting transition state indicates that this parameter determines product selectivity. Indeed, when the natural charge on boron is larger than 1, an amine is produced, whereas when the charge is less than 1, an imine is produced. Hence, the selectivity of products can be controlled by adjusting the natural charge of the boron atom in the Lewis acid catalyst.

Mobile Phone Addiction and Academic Procrastination Negatively Impact Academic Achievement Among Chinese Medical Students.

The problem of mobile phone addiction and academic procrastination among medical students has been widely acknowledged. This study aimed to explore the influence of demographic factors on mobile phone addiction, academic procrastination, and academic achievement among medical students. Further, it investigated the association between mobile phone addiction, academic procrastination, and academic achievement. This cross-sectional study was conducted between May and June 2019. A total of 3 511 medical students participated in an online questionnaire survey (effective response rate = 81.7%). Demographic factors, the Scale of Academic Achievement, the short scale of the Mobile Phone Problem Use (MPPUS-10), and the Academic Procrastination Scale-Short (APS-S) were used. Hierarchical multiple regression analysis revealed that the average scores for academic procrastination, mobile phone addiction, and academic achievement were 2.66 ± 0.91, 5.13 ± 1.53, and 4.51 ± 0.71, respectively. Moreover, there were significant differences in gender, grade, leadership experience, and family monthly income across mobile phone addiction, academic procrastination, and academic achievement. Mobile phone addiction was negatively associated with learning dedication, learning performance, and relationship facilitation. Academic procrastination was negatively associated with learning dedication, learning performance, relationship facilitation, and objective achievement. Mobile phone addiction and academic procrastination was revealed as prevalent among Chinese medical students, and negatively influences their academic achievement. It is critical to establish a more efficient learning environment for Chinese medical students to minimize the negative impact of mobile phone addiction and academic procrastination.

The Association Among Achievement Goal Orientations, Academic Performance, and Academic Well-Being Among Chinese Medical Students: A Cross-Sectional Study.

Learning motivation is a significant factor that ensures quality in medical education, and might affect the academic performance and well-being of medical students. This study aimed to explore the status of achievement goal orientations among medical students in China and to further identify the association among academic performance, academic well-being, and achievement goal orientations. Data were collected through a cross-sectional, anonymous survey conducted with 3,511 respondents (effective response rate = 81.7%), from four medical universities in China, and demographic factors, achievement goal orientations, academic performance, and academic well-being were assessed. The average score of achievement goal orientations of Chinese medical students suggested a difference in demographic factors, including sex, year of study, experience of leadership cadre, and family income. Both mastery and performance-avoidance goals were associated with academic performance, subjective academic stress, subjective learning adaptability, subjective sleep quality, and subjective well-being. Performance-approach goals were related to academic performance, subjective academic stress, and subjective learning adaptability. The achievement goal orientations of the medical students in this study were at a middle level. The findings emphasize the importance of mastery goals for promoting the academic performance and well-being of medical students. More care and attention toward achievement goal orientations can be beneficial for the improvement of the academic performance and well-being among medical students.

Insights into the nucleophilic substitution of pyridine at an unsaturated carbon center.

Bimolecular nucleophilic substitution (SN2) is a fundamental reaction that has been widely studied. So far, the nucleophiles are mainly anionic species in SN2 reactions. In this study, we use density functional theory calculations to assess the mechanisms of substitution of carbonyl, imidoyl, and vinyl compounds with a neutral nucleophile, pyridine. Charge decomposition analysis is performed to explore the main components of the transition state's LUMO. For reactions of imidoyl or carbonyl compounds with pyridine or Cl-, the LUMOs of the transition states are composed of mixed orbitals originating from the nucleophile and the substrate. Considering the unique mixed nature of the orbitals, the reaction mode is termed SN m (m means mix). Moreover, the main components of the transition state's LUMO are pure σ*C-Cl MO in the reactions of H2C[double bond, length as m-dash]CHCl with pyridine or Cl-. Computations were also performed for RY[double bond, length as m-dash]CHX substrates with different X and Y groups (X= Cl-, Br-, or F-; Y = O, N, or C).

Comparative DFT study of metal-free Lewis acid-catalyzed C-H and N-H silylation of (hetero)arenes: mechanistic studies and expansion of catalyst and substrate scope.

Direct selective dehydrogenative silylation of thiophenes, pyridines, indoles and anilines to synthesize silyl-substituted aromatic compounds catalyzed by metal-free Lewis acids was achieved recently. However, there is still insufficient mechanistic data for these transformations. Using density functional theory calculations, we conducted a detailed investigation of the mechanism of the B(C6F5)3-catalyzed dehydrogenative silylation of N-methylindole, N,N-dimethylaniline and N-methylaniline. We successfully located the most favourable reaction pathways that can explain the experimental observations notably well. The most favourable pathway for B(C6F5)3-catalyzed C-H silylation of N-methylindole includes nucleophilic attack, proton abstraction and hydride migration. The C-H silylation of N,N-dimethylaniline follows a similar pathway to N-methylindole rather than that proposed by Hou's group. Our mechanism successfully explains that the transformations of N-methylindoline to N-methylindole produce different products at different temperatures. For N-methylaniline bearing both N-H and para-phenyl C-H bonds, the N-H silylation reaction is more facile than the C-H silylation reaction. Our proposed mechanism of N-H silylation of N-methylaniline is different from that proposed by the groups of Paradies and Stephan. Lewis acids Al(C6F5)3, Ga(C6F5)3 and B(2,6-Cl2C6H3)(p-HC6F4)2 can also catalyze the C-H silylation of N-methylindole like B(C6F5)3, but the most favourable pathways are those promoted by N-methylindoline. Furthermore, we also found several other types of substrates that would undergo C-H or N-H silylation reactions under moderate conditions. These findings may facilitate the design of new catalysts for the dehydrogenative silylation of inactivated (hetero)arenes.

Density Functional Theory Mechanistic Study of Boron-Catalyzed N-Alkylation of Amines with Formic Acid: Formic Acid Activation by Silylation Reaction.

New methodology for the alkylation of amines is an intriguing issue in both academia and industry. Recently, several groups reported the metal-free B(C6 F5 )3 -catalyzed N-alkylation of amines, but the mechanistic details of these important reactions are unclear. Herein, a computational study was performed to elucidate the mechanism of the N-alkylation of amines with formic acid catalyzed by the Lewis acid B(C6 F5 )3 in the presence of hydrosilane. We found that the reaction started with the activation of formic acid through a novel model. Then, the high electrophilicity of the C center of the formic acid unit and the nucleophilic character of the amine resulted in a C-N coupling reaction. Finally, two sequential silyl-group and H- transfer steps occurred to generate the final product. Upon comparing the reaction barrier and the hydrogenation of indole, our mechanism is more favorable than that proposed by the group of Yu and Fu.

Charge-Transfer-Induced para-Selective sp2 C-H Bond Activation of Arenes by Use of a Hypervalent Iodine Compound: A Theoretical Study.

The reaction mechanism of the C-H bond activation of toluene promoted by the hypervalent iodine compound TIPP-I(OH)OTs was investigated in detail by density functional theory calculations. Our calculations show that a plausible reaction pathway of the C-H bond activation of toluene contains two stages: (1) the ligand exchange process on TIPP-I(OH)OTs, involving the substitution of the hydroxyl group and tosyloxyl group with TfOH, and (2) the C-H bond activation of toluene promoted by the hypervalent iodine center with the assistance of the triflate anion. The second step is the rate-limiting step with a relatively low free energy barrier of 19.6 kcal mol-1 in acetonitrile, which is in accord with the experimental fact that the reaction takes place at room temperature. Frontier molecular orbits and natural population analysis show that partial electron transfer from the toluene to the hypervalent iodine moiety occurs in the charge-transfer complex, resulting in the activation of the C-H bond at the para position of toluene. Further calculations show that this hypervalent iodine compound promoted C-H bond activation reaction will be effective if the substrate is electron-rich and a strong Brønsted acid is used.

Homolytic Cleavage of a B-B Bond by the Cooperative Catalysis of Two Lewis Bases: Computational Design and Experimental Verification.

Density functional theory (DFT) investigations revealed that 4-cyanopyridine was capable of homolytically cleaving the B-B σ bond of diborane via the cooperative coordination to the two boron atoms of the diborane to generate pyridine boryl radicals. Our experimental verification provides supportive evidence for this new B-B activation mode. With this novel activation strategy, we have experimentally realized the catalytic reduction of azo-compounds to hydrazine derivatives, deoxygenation of sulfoxides to sulfides, and reduction of quinones with B2 (pin)2 at mild conditions.

"Inverse" Frustrated Lewis Pairs--Activation of Dihydrogen with Organosuperbases and Moderate to Weak Lewis Acids.

A new approach to intermolecular frustrated Lewis pairs (FLPs) that combines readily available bulky organosuperbases with moderate to weak boron-containing Lewis acids is reported. These so-called "inverse" FLPs are demonstrated to heterolytically cleave dihydrogen, allowing for the isolation and structural characterization of various phosphonium borohydride salts; two FLPs proved to be efficient catalyst's in the metal-free hydrogenation of N-benzylidenaniline.

An insight into the Lewis acid-catalyzed intramolecular aminocyanation and oxycyanation of alkenes: a concerted or stepwise mechanism.

Density functional theory investigations reveal that the intramolecular additions of N-CN bonds to alkenes proceed in a novel asynchronous and concerted mechanism, while the intramolecular addition of O-CN bonds to alkenes may occur by both concerted and stepwise pathways.

Mechanistic insights into the full hydrogenation of 2,6-substituted pyridine catalyzed by the Lewis acid C6F5(CH2)2B(C6F5)2.

The reaction mechanism for the full hydrogenation of 2-phenyl-6-methyl-pyridine catalyzed by the Lewis acid C6F5(CH2)2B(C6F5)2 was investigated in detail by density functional theory calculations. Our calculations show that a plausible reaction pathway of the hydrogenation of pyridine contains five stages: (1) the generation of a new borane C6F5(CH2)2B(C6F5)2 from the hydroboration of the alkene, which forms a frustrated Lewis pair (FLP) with a pyridine; (2) the activation of H2 by FLP to yield an ion pair intermediate; (3) intramolecular hydride transfer from the boron atom to the pyridinium cation in the ion pair intermediate to produce the 1,4-dihydropyridine; (4) hydrogenation of the 1,4-dihydropyridine by the FLP to form the 1,4,5,6-tetrahydropyridine; (5) hydrogenation of the 1,4,5,6-tetrahydropyridine by the FLP to yield the final piperidine. The last two hydrogenation processes follow a similar pathway, which includes four steps: (a) proton transfer from the pyridinium moiety to the substrate; (b) dissociation of the newly generated pyridine; (c) hydride migration from the hydridoborate moiety to the protonated substrate to produce the hydrogenated product; (d) release of the hydrogenated product to regenerate the free borane. The full hydrogenation of pyridine is calculated to be exothermic by 16.9 kcal mol(-1), relative to the starting reactants. The rate-limiting step is the proton transfer in the second hydrogenation step, with a free energy barrier of 28.2 kcal mol(-1) in the gas phase (27.9 kcal mol(-1) in toluene) at room temperature and 1.0 atm. Our results can account for the observed experimental facts.

Association between fifteen risk factors and progressing ischemic stroke in the Han population of northeast China.

BACKGROUND: The mortality and disability associated with progressing ischemic stroke are much higher than general ischemic stroke. This study was conducted to determine the risk factors for progressing ischemic stroke in the Han population of northeast China. METHODS: A total of 2511 patients with ischemic stroke within 24 hours admitted to Department of Neurology, First Affiliated Hospital of Harbin Medical University were studied, from November 2007 to May 2009. All of the patients were classified into the progressing or non-progressing group according to the scores of the Scandinavian Neurological Stroke Scale. Fifteen putative risk factors were evaluated. The influence of risk factors for progressing ischemic stroke was analyzed with the simple Logistic analysis, the multiple Logistic analysis, and the stepwise Logistic regression model. All the statistical analysis was performed by SAS 9.1. RESULTS: Totally 359 (14.3%) patients met the criteria for progressing ischemic stroke. The Logistic analysis showed that age, family stroke history, smoking history, hypertension on admission, a drop in blood pressure after admission to the hospital, high serum glucose on admission, and fever were related to progressing ischemic stroke in the Han population of northeast China. CONCLUSION: People of the ischemic stroke with these factors are more likely to develop progressing ischemic stroke.