Autonomous closed-loop mechanistic investigation of molecular electrochemistry via automation.

Electrochemical research often requires stringent combinations of experimental parameters that are demanding to manually locate. Recent advances in automated instrumentation and machine-learning algorithms unlock the possibility for accelerated studies of electrochemical fundamentals via high-throughput, online decision-making. Here we report an autonomous electrochemical platform that implements an adaptive, closed-loop workflow for mechanistic investigation of molecular electrochemistry.

Interrogating the Mechanistic Features of Ni(I)-Mediated Aryl Iodide Oxidative Addition Using Electroanalytical and Statistical Modeling Techniques.

While the oxidative addition of Ni(I) to aryl iodides has been commonly proposed in catalytic methods, an in-depth mechanistic understanding of this fundamental process is still lacking. Herein, we describe a detailed mechanistic study of the oxidative addition process using electroanalytical and statistical modeling techniques. Electroanalytical techniques allowed rapid measurement of the oxidative addition rates for a diverse set of aryl iodide substrates and four classes of catalytically relevant complexes (Ni(BPy), Ni(Phen), Ni(Terpy), and Ni(BPP)).

Three-Stage Conversion of Chemically Inert -Heptane to α-Hydrazino Aldehyde Based on Bioelectrocatalytic C-H Bond Oxyfunctionalization.

Simple petrochemical feedstocks are often the starting material for the synthesis of complex commodity and fine and specialty chemicals. Designing synthetic pathways for these complex and specific molecular structures with sufficient chemo-, regio-, enantio-, and diastereo-selectivity can expand the existing petrochemicals landscape. The two overarching challenges in designing such pathways are selective activation of chemically inert C-H bonds in hydrocarbons and systematic functionalization to synthesize complex structures.

Investigating Oxidative Addition Mechanisms of Allylic Electrophiles with Low-Valent Ni/Co Catalysts Using Electroanalytical and Data Science Techniques.

The catalysis by a π-allyl-Co/Ni complex has drawn significant attention recently due to its distinct reactivity in reductive Co/Ni-catalyzed allylation reactions. Despite significant success in reaction development, the critical oxidative addition mechanism to form the π-allyl-Co/Ni complex remains unclear. Herein, we present a study to investigate this process with four catalysis-relevant complexes: Co(BPy)Br, Co(Phen)Br, Ni(BPy)Br, and Ni(Phen)Br.

Cobalt-electrocatalytic HAT for functionalization of unsaturated C-C bonds.

The study and application of transition metal hydrides (TMHs) has been an active area of chemical research since the early 1960s, for energy storage, through the reduction of protons to generate hydrogen, and for organic synthesis, for the functionalization of unsaturated C-C, C-O and C-N bonds. In the former instance, electrochemical means for driving such reactivity has been common place since the 1950s but the use of stoichiometric exogenous organic- and metal-based reductants to harness the power of TMHs in synthetic chemistry remains the norm. In particular, cobalt-based TMHs have found widespread use for the derivatization of olefins and alkynes in complex molecule construction, often by a net hydrogen atom transfer (HAT).

The efficacy of ankle arthroplasty on motor function recovery in patients with orthopedic ankle injury: a systematic review and meta-analysis.

Background: This study analyzed the effects of ankle arthroplasty on the recovery of motor function in patients with orthopedic ankle injury.

Methods: English databases including PubMed, Web of Science, Embase, and the Cochrane Library were searched for randomized controlled trials (RCTs) examining the effects of ankle arthroplasty, ankle replacement, and joint prosthesis on motor function recovery in patients with orthopedic ankle injury. The outcome indicators included the American Orthopedic Foot and Ankle Society (AOFAS) score, the 36-item short form survey (SF-36) score, the Foot and Ankle Ability Measures (FAAM) score, and the visual analog scale (VAS) score.

One-Pot Bioelectrocatalytic Conversion of Chemically Inert Hydrocarbons to Imines.

Petroleum hydrocarbons are our major energy source and an important feedstock for the chemical industry. With the exception of combustion, the deep conversion of chemically inert hydrocarbons to more valuable chemicals is of considerable interest. However, two challenges hinder this conversion.

Analyzing mechanisms in Co(i) redox catalysis using a pattern recognition platform.

Redox catalysis has been broadly utilized in electrochemical synthesis due to its kinetic advantages over direct electrolysis. The appropriate choice of redox mediator can avoid electrode passivation and overpotential, which strongly inhibit the efficient activation of substrates in electrolysis. Despite the benefits brought by redox catalysis, establishing the precise nature of substrate activation remains challenging.

-Ammonium Ylide Mediators for Electrochemical C-H Oxidation.

The site-specific oxidation of strong C(sp)-H bonds is of uncontested utility in organic synthesis. From simplifying access to metabolites and late-stage diversification of lead compounds to truncating retrosynthetic plans, there is a growing need for new reagents and methods for achieving such a transformation in both academic and industrial circles. One main drawback of current chemical reagents is the lack of diversity with regard to structure and reactivity that prevents a combinatorial approach for rapid screening to be employed.

Gold-Catalyzed Formal Hexadehydro-Diels-Alder/Carboalkoxylation Reaction Cascades.

A dual gold-catalyzed hexadehydro-Diels-Alder/carboalkoxylation cascade reaction is reported. In this transformation, the gold catalyst participated in the hexadehydro-Diels-Alder step, switching the mechanism from a radical type to a cationic one, and then the catalyst activated the resulting aryne to form an ortho-Au phenyl cation species, which underwent a carboalkoxylation rearrangement rather than the expected aryne-ene reaction.

Atom-Economical Cross-Coupling of Internal and Terminal Alkynes to Access 1,3-Enynes.

Selective carbon-carbon (C-C) bond formation in chemical synthesis generally requires prefunctionalized building blocks. However, the requisite prefunctionalization steps undermine the overall efficiency of synthetic sequences that rely on such reactions, which is particularly problematic in large-scale applications, such as in the commercial production of pharmaceuticals. Herein, we describe a selective and catalytic method for synthesizing 1,3-enynes without prefunctionalized building blocks.

A Computer-Interpretable Guideline for COVID-19: Rapid Development and Dissemination.

Background: COVID-19 is a global pandemic that is affecting more than 200 countries worldwide. Efficient diagnosis and treatment are crucial to combat the disease. Computer-interpretable guidelines (CIGs) can aid the broad global adoption of evidence-based diagnosis and treatment knowledge.

Stereodivergent Coupling of 1,3-Dienes with Aldimine Esters Enabled by Synergistic Pd and Cu Catalysis.

Herein we describe the use of synergistic Pd and Cu catalysis for stereodivergent coupling reactions between 1,3-dienes and aldimine esters. By using different enantiomers of the two metal catalysts, all four stereoisomers of the coupling products, which have two vicinal stereocenters, could be accessed with high diastereo- and enantioselectivity. This atom-economical cross-coupling reaction has a wide substrate scope and good functional group tolerance.

[Molecular mechanism underlying differentiation of HL-60 cells induced by hexamethylene bisacetamide].

The objective of this study was to investigate the effect of hexamethylene bisacetamide (HMBA) on differentiation of HL-60 cells and its possible molecular mechanism. HL-60 cells were co-cultured with different concentrations of HMBA (0.5, 1, 2 mmol/L) for 4 days, then the proliferation was assayed by MTT at different time points.

Role of Myc in differentiation and apoptosis in HL60 cells after exposure to arsenic trioxide or all-trans retinoic acid.

Acute promyelocytic leukemia (APL) is highly malignant and frequently expresses the PML-RARalpha (promyelocytic leukemia-retinoic acid receptor-alpha) fusion protein. This fusion protein is targeted by all-trans retinoic acid (ATRA) and arsenic trioxide (As2O3), presently used in APL therapy. We have evaluated effects of ATRA and As2O3 treatment in PML-RARalpha-negative HL60 promyelocytic leukemia cells, harboring amplified c-myc.

Down-regulation of CD44 contributes to the differentiation of HL-60 cells induced by ATRA or HMBA.

CD44 is highly expressed in human acute myeloid leukemia (AML) cells. Some experiments had shown that it was possible to reverse differentiation blockage in AML cells by CD44 ligation with specific antibodies, indicating that CD44 was closely related to the differentiation of leukemia cells. The differentiation of acute promyelocytic leukemia cell line HL-60 cells could be induced by all trans-retinoic acid (ATRA) and hexamethylene bisacetamide (HMBA), but so far the mechanism was not demonstrated clearly.

Down-regulation of TRRAP-dependent hTERT and TRRAP-independent CAD activation by Myc/Max contributes to the differentiation of HL60 cells after exposure to DMSO.

Myc/Max/Mad often play pivotal roles in the proliferation, apoptosis, differentiation and cell cycle progress of leukemia cells. Myc and Mad are known to be unstable proteins and their expression is tightly regulated throughout cell cycle progression and differentiation. Usually, c-Myc expression is implicated in cell growth and proliferation, and the deregulated expression of c-Myc in both myeloid leukemia cells and normal myeloid cells not only blocks terminal differentiation but also its associated growth arrest.

Immune tolerance in pancreatic islet xenotransplantation.

Aim: To observe the effect of tail vein injection with donor hepatocytes and/or splenocytes on the islet xenotransplantation rejection.

Methods: New-born male pigs and BALB/C mice were selected as donors and recipients respectively. Islet xenotransplantation was performed in recipients just after the third time of tail vein injection with donor hepatocytes and/or splenocytes.

Effect of arsenic trioxide on cytokine expression by acute promyelocytic leukemia cells.

Objective: To detect the expression of cytokines by acute promyelocytic leukemia (APL) cells before and after exposure to arsenic trioxide.

Methods: Diagnoses were performed according to the FAB cytological classification criteria and cytogenetic criteria. Bone marrow or blood samples from APL patients were collected in heparinized tubes, then primary APL cells were separated by traditional Ficoll-Hypaque density centrifugation and purified after adherence to plastic surfaces.

The role of donor hepatocytes and/or splenocytes pre-injection in reducing islet xenotransplantation rejection.

Objective: To observe the effect of tail vein injection with donor hepatocyte and/or splenocyte on islets xenotransplantation rejection.

Methods: New-born male pigs and BALB/C mice were selected as donors and recipients respectively. Islets xenotransplantation was performed in recipients just after the third time of tail vein injection with donor hepatocytes and/or splenocytes.