Diastereoselective, Zinc-Catalyzed Alkynylation of α‑Bromo Oxocarbenium Ions

We have developed a bromination/alkynylation sequence that enables efficient transformation of simple cyclic enol ethers to difunctionalized products. The success of this strategy relies on a highly diastereselective, zinc-catalyzed addition of terminal alkynes to α-bromo oxocarbenium ions, formed in situ via ionization of acetal precursors. Using this method, <i>trans-</i>α-alkynyl-β-halo pyran and furan derivatives can be prepared with high diastereoselectivity and excellent functional group tolerance

Enantioselective, Copper-Catalyzed Alkynylation of Ketimines To Deliver Isoquinolines with α‑Diaryl Tetrasubstituted Stereocenters

An enantioselective, copper-catalyzed alkynylation of cyclic α,α-diaryl ketiminium ions has been developed to deliver isoquinoline products with diaryl, tetrasubstituted stereocenters. The success of this reaction relied on identification of Ph-PyBox as the optimal ligand, <i>i</i>-Pr₂NEt as the base, and CHCl₃ as the solvent. A broad scope and functional group tolerance were observed. Notably, the use of both aryl and silyl acetylenes results in high yields and enantioselectivities. Mechanistic experiments are consistent with a dimeric or higher order catalyst

Ambient-Temperature Trap/Release of Arsenic by Dielectric Barrier Discharge and Its Application to Ultratrace Arsenic Determination in Surface Water Followed by Atomic Fluorescence Spectrometry

A novel dielectric barrier discharge reactor (DBDR) was utilized to trap/release arsenic coupled to hydride generation atomic fluorescence spectrometry (HG-AFS). On the DBD principle, the precise and accurate control of trap/release procedures was fulfilled at ambient temperature, and an analytical method was established for ultratrace arsenic in real samples. Moreover, the effects of voltage, oxygen, hydrogen, and water vapor on trapping and releasing arsenic by DBDR were investigated. For trapping, arsenic could be completely trapped in DBDR at 40 mL/min of O₂ input mixed with 600 mL/min Ar carrier gas and 9.2 kV discharge potential; prior to release, the Ar carrier gas input should be changed from the upstream gas liquid separator (GLS) to the downstream GLS and kept for 180 s to eliminate possible water vapor interference; for arsenic release, O₂ was replaced by 200 mL/min H₂ and discharge potential was adjusted to 9.5 kV. Under optimized conditions, arsenic could be detected as low as 1.0 ng/L with an 8-fold enrichment factor; the linearity of calibration reached <i>R</i>² > 0.995 in the 0.05 μg/L−5 μg/L range. The mean spiked recoveries for tap, river, lake, and seawater samples were 98% to 103%; and the measured values of the CRMs including GSB-Z50004-200431, GBW08605, and GBW­(E)­080390 were in good agreement with the certified values. These findings proved the feasibility of DBDR as an arsenic preconcentration tool for atomic spectrometric instrumentation and arsenic recycling in industrial waste gas discharge

Foci with significant changes in degree differences from non-drug users(NDUs) versus chronic heroin users(CHUs).

<p>Foci with significant changes in degree differences from non-drug users(NDUs) versus chronic heroin users(CHUs).</p

Significant differences in the intensity of the functional connection between the two groups' weighted region-based networks.

<p>Ten connections (red lines) showed increased intensity in the CHUs' resting networks (CHUs>NDUs), and a positive correlation with dependence duration in the CHUs' networks while controlling for the patients' age.</p

Significant degree differences between CHUs' unweighted voxel-based resting networks and NDUs' resting networks were at a threshold of T = 0.56.

<p>A two-sample two-tailed <i>t</i>-test was performed (<i>p</i><0.05, corrected). All clusters contain at least three contiguous voxels.</p

Genotype and allele frequencies of the BDNF Val66Met polymorphism in healthy young Chinese adults.

<p>Genotype and allele frequencies of the BDNF Val66Met polymorphism in healthy young Chinese adults.</p

VBM differences among three genotypes based on the BDNF Val66Met polymorphism.

<p>Top panel: areas with a significantly decreased GM volume in Met/Met group compared with Val/Val group (Met/Met < Val/Val, corrected, <i>P</i><0.05). Bottom left panel: areas with a significantly decreased GM volume in the Val/Met group compared with the Val/Val group (Val/Met < Val/Val, corrected, <i>P</i><0.05). Bottom left panel: areas with a significantly decreased GM volume in the Met carriers group (Met/Met+Val/Met) compared with the Val/Val group (Met carriers < Val/Val, corrected, <i>P</i><0.05 ). ACC, anterior cingulate cortex; MCC, middle cingulated cortex; MTC, middle temporal cortex; IC, insular cortex; IFC, inferior frontal cortex; OFC, orbital frontal cortex; PCC, posterior cingulate cortex; STC, superior temporal cortex.</p

Significant differences in the intensity of the functional connection between the two groups' weighted region-based networks.

<p>Sixteen connections (blue lines) exhibited decreased intensity in the CHUs' resting networks (CHUs</p

Areas with decreased cortical thickness in the Val/Met group compared with the Val/Val group based on the BDNF Val66Met polymorphism (FDR corrected, P<0.05).

<p>Areas with decreased cortical thickness in the Val/Met group compared with the Val/Val group based on the BDNF Val66Met polymorphism (FDR corrected, P<0.05).</p