A direct decarbonylative phosphorylation of benzoic acids catalyzed by palladium was disclosed. Under the reaction conditions, a wide range of benzoic acids coupled readily with all the three kinds ...of P(O)–H compounds, i.e. secondary phosphine oxides, H‐phosphinates and H‐phosphonates, producing the corresponding organophosphorus compounds in good to high yields. This reaction could be conducted at a gram scale and applied in the late‐stage phosphorylative modification of carboxylic acids drug molecules. These results well demonstrated the potential synthetic value of this new reaction in organic synthesis.
A direct decarbonylative phosphorylation of benzoic acids catalyzed by palladium was disclosed. Under the reaction conditions, a wide range of carboxylic acids coupled readily with all the three kinds of P(O)–H compounds, i.e. secondary phosphine oxides, H‐phosphinates and H‐phosphonates, producing the corresponding organophosphorus compounds in good to high yields. This reaction could be conducted at a gram scale and applied in the late‐stage phosphorylative modification of carboxylic acids drug molecules. These results well demonstrated the potential synthetic value of this new reaction in organic synthesis.
The strong interface is an essential requirement to ensure the effective load transfer of graphene/Cu composites. Here we attempted to improve the interface adhesion and mechanical properties of ...reduced graphene oxide (RGO)/CuCr composites by matrix-alloying with ∼0.2 at.% Cr. It was found that a trace amount of Cr7C3 layers/nanoparticles was in-situ formed at the RGO-CuCr interface, which contributed to the dramatically improved interfacial bonding of the composites. The 2.5 vol% RGO/CuCr composite exhibited a tensile strength of 352 MPa, 82% and 19% higher than that of unreinforced CuCr and 2.5 vol% RGO/Cu composite without Cr alloying, respectively. The enhanced strength of RGO/CuCr composite was ascribed to the dual role of Cr7C3 layers/nanoparticles that not only enhanced the load transfer efficiency, but also promoted the dislocation strengthening ability of RGO itself. Furthermore, we proposed the possible Cr7C3 formation/evolution mechanism that involved the four steps of amorphous carbon formation, Cr7C3 nucleation in amorphous carbon, Cr7C3 growth and Cr7C3 coalescence. The formation of medium sized Cr7C3 layers/nanoparticles at 1053 K resulted in the highest strength of RGO/CuCr composite with a satisfactory strength-ductility combination. This study provides new insights into the interface structure, strengthening mechanism and carbide formation/evolution mechanism of graphene/CuX composites.
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Alkynes are among the most fundamentally important organic compounds and are widely used in synthetic chemistry, biochemistry, and materials science. Thus, the development of an efficient and ...sustainable method for the preparation of alkynes has been a central concern in organic synthesis. Cross‐dehydrogenative coupling utilizing E−H and Z−H bonds in two different molecules can avoid the need for prefunctionalization of starting materials and has become one of the most straightforward methods for the construction of E−Z chemical bonds. This Review summarizes recent progress in the preparation of internal alkynes by cross‐dehydrogenative coupling with terminal alkynes.
Follow the CDC guidelines: The development of efficient and sustainable methods for the preparation of alkynes has been a central concern in organic synthesis. Cross‐dehydrogenative coupling can avoid the need for prefunctionalization of starting materials. This Review summarizes recent progress in the preparation of internal alkynes by cross‐dehydrogenative coupling with terminal alkynes.
Cross-species transmission of viruses from wildlife animal reservoirs poses a marked threat to human and animal health
. Bats have been recognized as one of the most important reservoirs for emerging ...viruses and the transmission of a coronavirus that originated in bats to humans via intermediate hosts was responsible for the high-impact emerging zoonosis, severe acute respiratory syndrome (SARS)
. Here we provide virological, epidemiological, evolutionary and experimental evidence that a novel HKU2-related bat coronavirus, swine acute diarrhoea syndrome coronavirus (SADS-CoV), is the aetiological agent that was responsible for a large-scale outbreak of fatal disease in pigs in China that has caused the death of 24,693 piglets across four farms. Notably, the outbreak began in Guangdong province in the vicinity of the origin of the SARS pandemic. Furthermore, we identified SADS-related CoVs with 96-98% sequence identity in 9.8% (58 out of 591) of anal swabs collected from bats in Guangdong province during 2013-2016, predominantly in horseshoe bats (Rhinolophus spp.) that are known reservoirs of SARS-related CoVs. We found that there were striking similarities between the SADS and SARS outbreaks in geographical, temporal, ecological and aetiological settings. This study highlights the importance of identifying coronavirus diversity and distribution in bats to mitigate future outbreaks that could threaten livestock, public health and economic growth.
Electrochemical reduction of N2 to NH3 is a promising method for artificial N2 fixation, but it requires efficient and robust electrocatalysts to boost the N2 reduction reaction (NRR). Herein, a ...combination of experimental measurements and theoretical calculations revealed that a hybrid material in which ZnO quantum dots (QDs) are supported on reduced graphene oxide (ZnO/RGO) is a highly active and stable catalyst for NRR under ambient conditions. Experimentally, ZnO/RGO was confirmed to favor N2 adsorption due to the largely exposed active sites of ultrafine ZnO QDs. DFT calculations disclosed that the electronic coupling of ZnO with RGO resulted in a considerably reduced activation‐energy barrier for stabilization of *N2H, which is the rate‐limiting step of the NRR. Consequently, ZnO/RGO delivered an NH3 yield of 17.7 μg h−1 mg−1 and a Faradaic efficiency of 6.4 % in 0.1 m Na2SO4 at −0.65 V (vs. RHE), which compare favorably to those of most of the reported NRR catalysts and thus demonstrate the feasibility of ZnO/RGO for electrocatalytic N2 fixation.
ZnO/RGO can fix it: A hybrid material, in which ZnO quantum dots are supported on reduced graphene oxide (ZnO/RGO), was synthesized by a facile, one‐step, microwave‐assisted solvothermal method and found to be a highly active and stable catalyst for the electrochemical reduction of dinitrogen to ammonia (see figure) under ambient conditions, which is a promising method for artificial nitrogen fixation.
The three‐component reaction of p‐quinone monoacetals, amines and diarylphosphine oxides is developed to afford m‐(diarylphosphinyl)anilides in moderate to high yields. The reaction may proceed via a ...process involving phospha‐nucleophilic addition to an iminoquinone acetal intermediate and/or carbonyl‐amine condensation with a phosphinyl enone intermediate.
Ph
3
P is found to be inert to sodium in toluene even on heating. This phenomenon leads to the finding that in toluene Ph
3
PS reacts with sodium efficiently and selectively to produce quantitative ...yields of highly valuable Ph
3
P and anhydrous Na
2
S. By applying this finding, anhydrous Na
2
S can be safely and conveniently prepared using a Ph
3
P-mediated reaction from sodium and sulfur. This finding also leads to the establishment of a feasible alternative strategy (the sulfur method) for the restoration of the Ph
3
PO waste to Ph
3
P that is greener and safer than the currently operating "chlorine method" using phosgene.
Ph
3
P is found to be inert to sodium in toluene even on heating.
Nickel-catalysed P-H/C-CN cross coupling reactions take place efficiently under mild reaction conditions affording the corresponding sp(2)C-P bonds. This transformation provides a convenient method ...for the preparation of arylphosphines and arylphosphine oxides from the readily available P-H compounds and arylnitriles.
Since remote sensing images are captured from the top of the target, such as from a satellite or plane platform, ship targets can be presented at any orientation. When detecting ship targets using ...horizontal bounding boxes, there will be background clutter in the box. This clutter makes it harder to detect the ship and find its precise location, especially when the targets are in close proximity or staying close to the shore. To solve these problems, this paper proposes a deep learning algorithm using a multiscale rotated bounding box to detect the ship target in a complex background and obtain the location and orientation information of the ship. When labeling the oriented targets, we use the five-parameter method to ensure that the box shape is maintained rectangular. The algorithm uses a pretrained deep network to extract features and produces two divided flow paths to output the result. One flow path predicts the target class, while the other predicts the location and angle information. In the training stage, we match the prior multiscale rotated bounding boxes to the ground-truth bounding boxes to obtain the positive sample information and use it to train the deep learning model. When matching the rotated bounding boxes, we narrow down the selection scope to reduce the amount of calculation. In the testing stage, we use the trained model to predict and obtain the final result after comparing with the score threshold and nonmaximum suppression post-processing. Experiments conducted on a remote sensing dataset show that the algorithm is robust in detecting ship targets under complex conditions, such as wave clutter background, target in close proximity, ship close to the shore, and multiscale varieties. Compared to other algorithms, our algorithm not only exhibits better performance in ship detection but also obtains the precise location and orientation information of the ship.
A novel method for the iodine-mediated reduction of phosphine oxides (sulfides) to phosphines using phosphonic acid under solvent-free conditions is described. By using a combination of H3PO3 and I2, ...both tertiary monophosphine oxides and bis-phosphine oxides were reduced under this system, readily producing monodentate and bidentate phosphines, respectively, in good yields. Notably, chiral (R)-(+)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl dioxide could be also tolerated without racemization. This new approach is inexpensive and features simple conditions and a wide substrate scope.
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