Molybdenum-Catalyzed Cross-Coupling of Benzyl Alcohols: Direct C–OH Bond Transformation via [2 + 2]-Type Addition and Elimination

Traditional cross-couplings catalyzed by transition metal catalysts generally rely on the classic oxidative addition–transmetalation–reductive elimination process, which requires low-valent precious metals and an inert atmosphere and which initiates from carbon–alide or pesudo carbon–halide bonds. Herein, an unprecedented molybdenum–oxo-complex-catalyzed intermolecular cross-coupling of benzyl alcohols has been reported. Various alcohols including primary, secondary, and tertiary substrates can proceed efficiently under these conditions. Several functional groups sensitive to the low-valent transition metals, such as aryl halides, can be well tolerated. The mechanistic studies and DFT calculations suggest that an intramolecular concerted cyclization was involved in the reverse [2 + 2]-type elimination process

DataSheet_1_Grazing exclusion is more beneficial for restoring soil organic carbon and nutrient balance than afforestation on degraded sandy land.docx

IntroductionVegetation restoration is an effective measure to improve the ecosystem service of degraded sandy land ecosystem. However, it is unclear how vegetation restoration on severely desertified land affect soil organic carbon (SOC) sequestration and nutrients balance. Therefore, this study was designed to clarify the response of SOC, total nitrogen (TN), total phosphorus (TP), and the resulting stoichiometric ratios (C:N:P) to afforestation and grazing exclusion, and to quantify their dynamics over time.MethodsWe conducted vegetation community investigation and soil sampling in natural sparse-forest grassland (the climax community stage), afforestation (Pinus sylvestris var. mongolica (40-year, 48-year), Caragana microphylla (20-year, 40-year)), and grazing exclusion (20-year, 40-year) in China’s Horqin Sandy Land. Soil C:N:P stoichiometry and its driving factors under different restoration measures were then studied.ResultsAfforestation and grazing exclusion significantly (p ConclusionIn terms of ecological stoichiometry, grazing exclusion was more conducive to restore SOC and nutrient balance than afforestation on severely desertified land. Due to the poor soil nutrients, attentions should be paid to the soil nutrients and water conditions in the later stages of vegetation restoration. Those findings can provide valuable information for the restoration of degraded sandy land in semi-arid areas.</p

Image_1_Changes in temperature and precipitation extremes in the arid regions of China during 1960–2016.jpg

Extreme climate events have a greater impact on natural and human systems than average climate. The spatial and temporal variation of 16 temperature and nine precipitation extremal indices was investigated using the daily maximum and minimum surface air temperature and precipitation records from 113 meteorological stations in China’s arid regions from 1960 to 2016. The warmth indices [warm spell duration (WSDI); numbers of warm nights, warm days, tropical nights (TR), and summer days (SU)] increased significantly. On the contrary, the cold indices [numbers of frost days (FD), ice days (ID), cool days, and cool nights; cold spell duration (CSDI)] decreased significantly. The number of FD decreased fastest (−3.61 days/decade), whereas the growing season length (GSL) increased fastest (3.17 days/decade). The trend was strongest for diurnal temperature range (DTR) (trend rate = −7.29, P < 0.001) and minimum night temperature (trend rate = 7.70, P < 0.001). The cold extreme temperature events increased with increasing latitude, but the warm extreme temperature events decreased. Compared with temperature indices, the precipitation indices exhibited much weaker changes and less spatial continuity. Overall, changes in precipitation extremes present wet trends, although most of the changes are insignificant. The regionally averaged total annual precipitation for wet days increased by 4.78 mm per decade, and extreme precipitation events have become more intense and frequent during the study period. The spatial variability of extreme precipitation in the region was primarily influenced by longitude. Furthermore, the climate experienced a warm-wet abrupt climate change during 1990s.</p

miR-93-5p knockdown repressed hepatocellular carcinoma progression via increasing ERBB4 and TETs-dependent DNA demethylation

microRNAs (miRNAs) are involved in hepatocellular carcinoma (HCC) development and can control gene expression via directly targeting or regulating DNA methylation. This research aims to analyse the mechanism of miR-93-5p on HCC progression. miR-93-5p, Erb-B2 receptor tyrosine kinase 4 (ERBB4) and ten-eleven translocation methyl-cytosine dioxygenases (TET1, TET2 and TET3) abundances were measured via quantitative reverse transcription polymerase chain reaction and Western blotting. The binding interaction was examined by dual-luciferase reporter analysis and chromatin immunoprecipitation. Cell proliferation and apoptosis were assessed via Cell Counting Kit-8, colony formation and flow cytometry. The DNA methylation of ERBB4 was detected via specific polymerase chain reaction. SNU-449 cells were subcutaneously inoculated into the BALB/c nude mice to establish the in vivo model for HCC, and the in vivo function of miR-93-5p was analysed by intratumoral injections of miR-93-5p antogomir. miR-93-5p abundance was enhanced and ERBB4 level was reduced in HCC tumour tissues of 62 patients and HCC cell lines, in contrast with that in paired normal tissues of 62 patients and normal cell lines. ERBB4 was targeted by miR-93-5p. miR-93-5p knockdown or ERBB4 overexpression repressed HCC cell proliferation and promoted apoptosis via decreasing cell viability and colony ability and inducing cycle arrest. ERBB4 silence attenuated the influence of miR-93-5p knockdown on cell proliferation and apoptosis. ERBB4 promoter DNA methylation level was enhanced in HCC samples and cell lines, and ERBB4 abundance was increased via TETs (TET1, TET2 and TET3). miR-93-5p targeted TETs to modulate ERBB4 abundance. TETs silence relieved the influence of miR-93-5p knockdown on cell proliferation and apoptosis. miR-93-5p knockdown decreased HCC growth in a xenograft model. miR-93-5p knockdown repressed the progression of HCC via increasing ERBB4 and TETs-dependent DNA demethylation.</p

Micron-Thick Hexagonal Boron Nitride Crystalline Film for Vacuum Ultraviolet Photodetection with Improved Sensitivity and Spectral Response

Hexagonal boron nitride crystalline film with a thickness of 70 μm is deposited on a c-plane sapphire at 1700 °C by the chemical vapor deposition (CVD) method. In X-ray diffraction (XRD) characterizations, a peak of (002) is observed at 26.01° with the full width at half-maximum (FWHM) of 1.17°, and the c-axis lattice constant is estimated to be 6.84 Å. The characterization results of Raman and X-ray photoelectron spectroscopy further confirm the film’s high quality. Based on the h-BN film, a vacuum ultraviolet (VUV) photodetector is further fabricated with a responsivity of 48.7 μA/W, exhibiting a photo-to-dark current ratio (PDCR) of more than 103 as well as an excellent spectral selectivity to short-wave ultraviolet irradiation. By analyzing the photoresponse process, the influence of different response mechanisms is explained, implying the photodetector’s ability to respond quickly

Image_2_Changes in temperature and precipitation extremes in the arid regions of China during 1960–2016.jpg

Extreme climate events have a greater impact on natural and human systems than average climate. The spatial and temporal variation of 16 temperature and nine precipitation extremal indices was investigated using the daily maximum and minimum surface air temperature and precipitation records from 113 meteorological stations in China’s arid regions from 1960 to 2016. The warmth indices [warm spell duration (WSDI); numbers of warm nights, warm days, tropical nights (TR), and summer days (SU)] increased significantly. On the contrary, the cold indices [numbers of frost days (FD), ice days (ID), cool days, and cool nights; cold spell duration (CSDI)] decreased significantly. The number of FD decreased fastest (−3.61 days/decade), whereas the growing season length (GSL) increased fastest (3.17 days/decade). The trend was strongest for diurnal temperature range (DTR) (trend rate = −7.29, P < 0.001) and minimum night temperature (trend rate = 7.70, P < 0.001). The cold extreme temperature events increased with increasing latitude, but the warm extreme temperature events decreased. Compared with temperature indices, the precipitation indices exhibited much weaker changes and less spatial continuity. Overall, changes in precipitation extremes present wet trends, although most of the changes are insignificant. The regionally averaged total annual precipitation for wet days increased by 4.78 mm per decade, and extreme precipitation events have become more intense and frequent during the study period. The spatial variability of extreme precipitation in the region was primarily influenced by longitude. Furthermore, the climate experienced a warm-wet abrupt climate change during 1990s.</p

Features of patients with mSIA grouped by primary tumor surgery before and after PSM.

(DOCX)</p

K-M curves for OS and CSS in metastatic small bowel cancer patients after PSM.

(A) OS of mSIA with and without primary tumor surgery. (B) CSS of mSIA with and without primary tumor surgery. (C) OS of mSI-NETs with and without primary tumor surgery. (D) CSS of mSI-NETs with and without primary tumor surgery. (E) OS of mSIA with and without metastatic surgery. (F) CSS of mSIA with and without metastatic surgery. (G) OS of mSI-NETs with and without metastatic surgery. (H) CSS of mSI-NETs with and without metastatic surgery.</p

Features of patients with mSI-NETs grouped by RNE before and after PSM.

(DOCX)</p

K-M curves for OS and CSS in metastatic small bowel cancer patients who received different treatment regimens.

(A) OS of mSIA. (B) CSS of mSIA. (C) OS of mSI-NETs. (D) CSS of mSI-NETs.</p