Benzidine was found to be a novel transient directing group to enable Pd-catalyzed direct selenylation of inert C(sp2)–H bonds of benzaldehydes. Diverse diarylselenides were readily constructed in ...high efficiency and satisfactory yields with good functional group tolerance. The practical usage of the method was further demonstrated by enlarged reaction to gram scale and application in the facile access to two selenoxanthenes and one fluorescent probe.
To reveal phosphorus (P) release pathways from sediment and their mechanisms induced by organic matter enrichment, 116 sampling sites (including surface water and sediment) in 29 shallow lakes with ...different eutrophic degrees in Wuhan city, China, were investigated from July 2011 to November 2011. Empirical relationship and structural equation model indicated that the decomposition of total organic matter (TOM), including proteins (PRT), carbo-hydrates (CHO) and lipids (especially PRT) mediated by extracellular enzymes, accelerated the formation of anaerobic status. On the other hand, coupled nitrification-denitrification caused by ammonium (NH4+-N) accumulation due to PRT decomposition further aggravated anaerobic status and nitrate removal in terms of the increase of dehydrogenase activity (DHA). As a consequence, ferric iron was reduced to ferrous iron and soluble reactive phosphorus (SRP) was released from iron-bound phosphorus (Fe(OOH)~P) in sediments. In addition, extracellular alkaline phosphatase can be induced by organic carbon and nitrogen on condition that the input of nitrogen (N) and carbon (C) exceeded by far that of P. Taken together, enrichment of N and C can result in P release through the formation of anaerobic status and alkaline phosphatase production. Hence, we indicated that a close coupling existed among C, N and P cycles.
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•Organic carbon and nitrogen enrichment stimulates phosphorus release.•The pathways included anaerobic release and phosphatase production.•The anaerobic status is related to organic carbon decomposition and nitrification•Phosphatase is secreted to supply P consumption.•Carbon, Nitrogen and Phosphorus cycles are coupled.
A photoelectrochemical sensor was developed with stepwise decoration of g-C3N4 quantum dots and chiral multifarene3,2,1 to achieve the ultrasensitive enantiorecognition for L-thyroxine.
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•A facile method for preparation of g-C3N4 quantum dots was discovered.•A photoelectrochemical sensor built with g-C3N4 QDs and chiral macrocycle was developed.•The ultrasensitive enantiorecognition for thyroxine was reached with the proposed photoelectrochemical sensor.
With a facile preparation for graphitic carbon nitride quantum dots (g-C3N4 QDs), an ultrasensitive photoelectrochemical (PEC) sensor was developed with the supramolecular affinity of chiral multifarene3,2,1 (CMF) to a hormone drug, thyroxine (T4), for efficient identification of thyroxine enantiomers. In the principle that g-C3N4 QDs was employed to achieve the photocurrent response and the macrocyclic compound served as the supramolecular enantiorecognition for thyroxine, the photoelectrochemical electrode was constructed by layer-by-layer assembly of g-C3N4 QDs and CMF on the surface of ITO (ITO-g-C3N4-CMF QDs). The proposed PEC sensor produced the limits of detection low to 67 pM towards L-T4 and 85 pM towards D-T4 in a concentration range from 0.1 nM to 10 nM, which was superior to the values in pioneering reports with colorimetric or electrochemical methods. With good stability, reproducibility, repeatability anti-interference ability, and acceptable recoveries, the proposed PEC sensor was employed for quantitative determination of L/D-T4 in water, human serum and commercial tablet.
We propose a new kind of qubits composed of electric dipolar molecules. The electric dipolar molecules in an external electric field will take simple harmonic oscillations, whose quantum states ...belonging to the two lowest energy levels act as the states
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of a qubit. The qubits’ excited states have a very long controlled mean life time about several seconds. We can perform quantum computations by manipulating the qubits of electric dipolar molecules just like those of neutral atoms. When the qubits are used for quantum computations, the dipolar moments’ orientations will harmonically oscillate along an external electric field and they will not change the directions: along or against the electric field, so the qubits can be large-scalely manufactured in graphene system. The radius of Rydberg blockade is about 100 nm.
Aims and objectives
To explore whether the risk of peripheral venous catheters failure remained constant throughout catheter use in adult patients.
Background
Peripheral venous catheters, widely used ...in adult patients, may have a critical threshold dwell time associated with increased risk of catheter failure.
Design
Prospective, observational study. We have complied with the STROBE checklist of items.
Methods
This study was conducted from July–October 2018 in Hunan, China. Data on patient factors, catheter factors and catheter failure events were collected. Poisson regression was used to assess the effect of catheter dwell time on catheter failure while adjusting for other variables.
Results
A total of 1,477 patients were included in the analysis. There were 854 cases (57.8%) of catheter failure. The median dwell time to catheter failure was 52 hr (interquartile range: 36–73 hr). The incidence rate of catheter failure significantly increased by 1.1%/h in the first 38 hr after catheter insertion. From 39–149 hr, the incidence rate significantly decreased, and at >149 hr, there was no significant change in the incidence rate. Meanwhile, factors such as vascular quality and infused drugs showed having an impact on catheter failure events.
Conclusions
The risk of catheter failure may not remain constant throughout the dwell time. The results suggest that nurses should assess the insertion site frequently in the first 38 hr.
Relevance to clinical practice
The significant increase in the risk of catheter failure per hour may warrant close and frequent inspection of insertion site during the first 38 hr.
N,O-aminals, molecules bearing a geminally N,O-substituted (stereogenic) carbon center, have been recently recognized as an important class of building blocks in organic synthesis. As direct ...precursors of imines and iminium ions, N,O-aminals were converted through asymmetric organocatalysis or metal catalysis to diverse enantiomerically enriched compounds including N-heterocycles. Furthermore, cyclic N,O-hemiaminals acted as acyclic amino aldehyde surrogates, which were transformed to enantioenriched products otherwise challenging to access. Finally, cyclic N,O-aminals were formed in situ as key intermediates in asymmetric catalysis. In this review, we introduce a wide array of catalytic asymmetric protocols involving the use of four distinct types of N,O-aminals as starting materials or key intermediates.
Seven conodont biozones are recognized in the carbonate-dominated shelf-marine Middle Ordovician developed in the intracratonic sedimentary basins (Canning, Amadeus and Georgina) of central and ...north-western Australia, in the Lachlan and New England orogens of New South Wales, and in the Takaka Terrane of New Zealand. A separate scheme identifying seven conodont biozones spanning the Middle Ordovician has also been developed for siliciclastic sequences deposited in slope-basinal environments in the Lachlan Orogen in New South Wales and Victoria. This biozonal classification consisting of two parallel biostratigraphic schemes for the shelf-marine and deep-marine successions respectively has significantly increased precision in regional and global biostratigraphic correlation and laid a solid foundation for the Middle Ordovician chronostratigraphy of Australia and New Zealand. Recognition of short-ranging pandemic species as the eponymous species of the biozones also supports direct correlation with the classical conodont successions established in Baltoscandia and the North American Midcontinent, and with those of the major Chinese terranes (South and North China and Tarim). The Lachlan Orogen appears to be globally unique in enabling correlation of contemporaneous conodont faunas over a considerable spectrum of water depths and biofacies ranging from carbonate shelves, slopes to deep-water basins.
This study aims to provide a systematic review of existing research on the use of digital game-based learning (DGBL) technology for foreign language (English) in preschool and elementary schools. ...Digital game-based technology enables learning to become more interactive and inspirational, thereby enhancing language acquisition. The authors present a DGBL classification schema with four main components, design principles, language content, pedagogical factors, and feedback mechanisms, as guidelines for designing and implementing DGBL in foreign language learning. This survey classifies and filters 110 published articles from January 2010 to April 2022 based on the proposed DGBL schema adhering to the insertion and omission criteria, from which 50 studies focus on preschool and primary school students between the ages of 2 and 10 years. The findings indicate that DGBL influences motivation, creativity, and problem-solving ability. However, the synthesized literature also reveals challenges and issues in designing and developing DGBL systems based on novel technologies. The findings are fundamental for exploring the game classification schema for designing and implementing game-based learning to augment the trends of DBGL in foreign language learning and identify the possible issues and solutions for DGBL to lessen health concerns and technology challenges. The authors recommend emerging technologies and software engineering processes as possible solutions for continuity in DGBL research by enlightening the significance of evolving technologies such as artificial intelligence, blockchain, deep learning, AR/VR, and DevOps.
