A general copper-catalysed enantioconvergent C(sp3)-S cross-coupling via biomimetic radical homolytic substitution.

Although α-chiral C(sp3)-S bonds are of enormous importance in organic synthesis and related areas, the transition-metal-catalysed enantioselective C(sp3)-S bond construction still represents an underdeveloped domain probably due to the difficult heterolytic metal-sulfur bond cleavage and notorious catalyst-poisoning capability of sulfur nucleophiles. Here we demonstrate the use of chiral tridentate anionic ligands in combination with Cu(I) catalysts to enable a biomimetic enantioconvergent radical C(sp3)-S cross-coupling reaction of both racemic secondary and tertiary alkyl halides with highly transformable sulfur nucleophiles. This protocol not only exhibits a broad substrate scope with high enantioselectivity but also provides universal access to a range of useful α-chiral alkyl organosulfur compounds with different sulfur oxidation states, thus providing a complementary approach to known asymmetric C(sp3)-S bond formation methods. Mechanistic results support a biomimetic radical homolytic substitution pathway for the critical C(sp3)-S bond formation step.

Polarization Switching and Correlated Phase Transitions in Fluorite-Structure ZrO2 Nanocrystals.

Unconventional ferroelectricity in fluorite-structure oxides enables tremendous opportunities in nanoelectronics owing to their superior scalability and silicon compatibility. However, their polarization order and switching process remain elusive due to the challenges of visualizing oxygen ions in nanocrystalline films. In this work, the oxygen shifting during polarization switching and correlated polar-nonpolar phase transitions are directly captured among multiple metastable phases in freestanding ZrO2 thin films by low-dose integrated differential phase-contrast scanning transmission electron microscopy (iDPC-STEM). Bidirectional transitions between antiferroelectric and ferroelectric orders and interfacial polarization relaxation are clarified at unit-cell scale. Meanwhile, polarization switching is strongly correlated with Zr-O displacement in reversible martensitic transformation between monoclinic and orthorhombic phases and two-step tetrahedral-to-orthorhombic phase transition. These findings provide atomic insights into the transition pathways between metastable polymorphs and unravel the evolution of polarization orders in (anti)ferroelectric fluorite oxides.

Using brain functional magnetic resonance imaging to evaluate the effectiveness of acupuncture combined with mirror therapy on upper limb function in patients with cerebral ischemic stroke: a study protocol for a randomized, controlled trial.

BACKGROUND: Upper limb and hand motor dysfunction is one of the challenges in rehabilitation after cerebral ischemic stroke (CIS), and the clinical efficacy of rehabilitation needs to be improved. This study aims to combine Jin's three-needle acupuncture (JTN) therapy with mirror therapy (MT) for hemiplegia after CIS, objectively evaluate the clinical effects and safety of JTN to treat upper limb dysfunction, and use functional magnetic resonance imaging (fMRI) of the brain to investigate the central mechanisms of the effects, which would provide a powerful evidence-based medical basis for further supporting the application of JTN combined with MT. METHODS/DESIGN: This trial will be a single-blind, randomized controlled study. Patients who meet the study criteria will be recruited and randomly assigned to either the combined treatment group (JTN+MT) or the JTN group. Both interventions will be conducted for 6 days per week and last for 4 weeks. The primary outcome will be the effective rate based on the Fugl-Meyer Assessment for Upper Extremity (FMA-UE). Other outcome measures will include scores on the motor assessment scale (MAS), action research arm test (ARAT), activities of daily living (ADL) scale, and fMRI analyses. For safety evaluation, adverse events will be observed and recorded. DISCUSSION: This study may help to identify the efficacy and safety of acupuncture combined with MT for upper limb dysfunction after CIS and explore the central mechanisms with brain fMRI. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR-IOR-17012174 . Registered on 5 April 2017.

Near-infrared light control of bone regeneration with biodegradable photothermal osteoimplant.

Mild heat stimulation can promote the restoration of bone defects but unfortunately, the delivery of exo-hyperthermy into human body is not efficient enough. In this study, mild heat-induced osteogenesis with high efficacy is demonstrated on an osteoimplant composed of black phosphorus nanosheets and poly(lactic-co-glycolic acid) (BPs@PLGA) with the participation of near-infrared (NIR) light irradiation. BPs@PLGA with only 0.2 wt% BPs show the highly-efficient NIR photothermal response even when being covered by a biological tissue as thick as 7 mm. In addition, this composite is completely biodegradable and the final degradation products are harmless H2O, CO2 and PO43- which can serve as necessary bone ingredient. The BPs@PLGA specimen mediated by low intensity and periodic NIR irradiation can effectively up-regulate the expressions of heat shock proteins and finally promote osteogenesis in vitro and in vivo. Boasting good biodegradability and NIR-mediated osteogenetic performances, the BPs@PLGA implant has great potential in orthopedic applications and this study provides new insights into the design and fabrication of new-style osteoimplants which can be remotely controlled.

Preparation of cucumber seed peptide-calcium chelate by liquid state fermentation and its characterization.

A specific cucumber seed peptide (CSP) was successfully produced by liquid state fermentation with B. subtilis HYT. Then the CSP was divided into four kind molecular weight components (CSP, untreated; CSP1, MW>10kDa; CSP2, 6kDa

[Chemical components of essential oils from Meconopsis oliverana and their antioxidant activity].

OBJECTIVE: To study the chemical components of essential oils from Meconopsis oliverana and their antioxidant activity. METHOD: The essential oil was extracted by steam distillation, and GC-MS analysis was used to identify its constituents. The OH free radical scavenging activity of the essential oils was evaluated with an enzyme mark instrument by assay of the ability of DPPH free radical scavenging. BHT was used as positive control. RESULT: Forty-seven compounds, account for 91.866% of the essential oils, were identified. The ability of scavenging OH and DPPH radicals of the essential oils is stronger than that of BHT. CONCLUSION: The main chemical constituents of the essential oils from M. oliverana are n-hexadecanoic acid (27.653%) and 6,10,14-trimethyl-2-pentadecanone (16.330%). And the essential oils showed strong antioxidant activity.