Click chemistry focuses on the development of highly selective reactions using simple precursors for the exquisite synthesis of molecules. Undisputedly, the CuI‐catalyzed azide–alkyne cycloaddition ...(CuAAC) is one of the most valuable examples of click chemistry, but it suffers from some limitations as it requires additional reducing agents and ligands as well as cytotoxic copper. Here, we demonstrate a novel strategy for the azide–alkyne cycloaddition reaction that involves a photoredox electron‐transfer radical mechanism instead of the traditional metal‐catalyzed coordination process. This newly developed photocatalyzed azide–alkyne cycloaddition reaction can be performed under mild conditions at room temperature in the presence of air and visible light and shows good functional group tolerance, excellent atom economy, high yields of up to 99 %, and absolute regioselectivity, affording a variety of 1,4‐disubstituted 1,2,3‐triazole derivatives, including bioactive molecules and pharmaceuticals. The use of a recyclable photocatalyst, solar energy, and water as solvent makes this photocatalytic system sustainable and environmentally friendly. Moreover, the azide–alkyne cycloaddition reaction could be photocatalyzed in the presence of a metal‐free catalyst with excellent regioselectivity, which represents an important development for click chemistry and should find versatile applications in organic synthesis, chemical biology, and materials science.
One more click! A novel design strategy for the azide–alkyne cycloaddition reaction by visible‐light catalysis through a photoredox electron‐transfer process (see scheme) has been developed for the first time. The reaction can be performed with a metal‐free catalyst in water using solar energy, making this a sustainable and environmentally friendly photocatalytic system, and represents an important development for click chemistry.
Trade promotion plays a critical role in real-world marketing and operations management. However, previous research paid rare attention to how to provide trade promotions in a sustainable manner when ...consumer demand is disrupted. Considering that demand disruption is becoming surging because of the digital economy, it is quite necessary to discern the managerial implications for sustainable trade promotion practice in demand disruption scenarios. For this purpose, we analyze trade promotions under demand disruption by integrating demand uncertainty and limited capacity into a stylized demand disruption model. Three trade promotion types, i.e. off-invoice, scan-back, and revenue-sharing, are examined, and optimal promotion decisions are derived for each strategy. Our results show that both manufacturer and retailer would adopt aggressive pricing strategies as the demand disruption being intensified. For trade promotion strategies, our results show that, for a certain level of demand disruption, the manufacturer prefers off-invoice rather than revenue-sharing when the manufacturer needs to offer a more aggressive trade promotion. This result indicates that, when aggressive trade promotions are needed, the manufacturer may be worse off by a revenue-sharing strategy, even though the revenue-sharing could coordinate a supply chain.
Advanced beyond-silicon electronic technology requires both channel materials and also ultralow-resistance contacts to be discovered
. Atomically thin two-dimensional semiconductors have great ...potential for realizing high-performance electronic devices
. However, owing to metal-induced gap states (MIGS)
, energy barriers at the metal-semiconductor interface-which fundamentally lead to high contact resistance and poor current-delivery capability-have constrained the improvement of two-dimensional semiconductor transistors so far
. Here we report ohmic contact between semimetallic bismuth and semiconducting monolayer transition metal dichalcogenides (TMDs) where the MIGS are sufficiently suppressed and degenerate states in the TMD are spontaneously formed in contact with bismuth. Through this approach, we achieve zero Schottky barrier height, a contact resistance of 123 ohm micrometres and an on-state current density of 1,135 microamps per micrometre on monolayer MoS
; these two values are, to the best of our knowledge, the lowest and highest yet recorded, respectively. We also demonstrate that excellent ohmic contacts can be formed on various monolayer semiconductors, including MoS
, WS
and WSe
. Our reported contact resistances are a substantial improvement for two-dimensional semiconductors, and approach the quantum limit. This technology unveils the potential of high-performance monolayer transistors that are on par with state-of-the-art three-dimensional semiconductors, enabling further device downscaling and extending Moore's law.
Energy and environmental issues have recently aroused increasing interest in China and many approaches are used to evaluate energy and environmental performance. In this paper, a two-stage network ...DEA framework is applied to evaluate the efficiency of energy saving and emission reduction in China during the period of the eleventh five-year plan, from 2006 to 2010. In this study, economic activities are divided into production and treatment processes. This is different from previous research which generally focused on either environmental efficiency or energy efficiency, omitting the integration of energy and environmental measures. Today, energy saving and emission reduction are both parts of the basic state policy of China and are equally important. The empirical results in this study show that: (i) eastern China has the best energy saving and emission reduction efficiency, performing is better than western and central China. (ii) The efficiency of the production process in central China is better than that in western China while the western area performs better than the central area in term of treatment efficiency. (iii) Integrated efficiency of energy saving and emission reduction of China was relatively stable in the five years and the pollution treatment efficiency maintained a rising trend.
•We measured China's regional energy saving and emission reduction efficiency using two-stage DEA approach.•The production and treatment processes are incorporated in evaluation.•Eastern China performs best in terms of energy saving and emission reduction efficiency.•Integrated efficiency of energy saving and emission reduction of China kept a stable trend during 2006–2010.
The observational association between gut microbiome and systemic lupus erythematosus (SLE) has been well documented. However, whether the association is causal remains unclear. The present study ...used publicly available genome-wide association study (GWAS) summary data to perform two-sample Mendelian randomization (MR), aiming to examine the causal links between gut microbiome and SLE. Two sets of MR analyses were conducted. A group of single nucleotide polymorphisms (SNPs) that less than the genome-wide statistical significance threshold (5 × 10
-8
) served as instrumental variables. To obtain a comprehensive conclusion, the other group where SNPs were smaller than the locus-wide significance level (1 × 10
-5
) were selected as instrumental variables. Based on the locus-wide significance level, the results indicated that there were causal effects of gut microbiome components on SLE risk. The inverse variance weighted (IVW) method suggested that
Bacilli
and
Lactobacillales
were positively correlated with the risk of SLE and
Bacillales
,
Coprobacter
and
Lachnospira
were negatively correlated with SLE risk. The results of weighted median method supported that
Bacilli
,
Lactobacillales
, and
Eggerthella
were risk factors for SLE and
Bacillales
and
Coprobacter
served as protective factors for SLE. The estimates of MR Egger suggested that genetically predicted
Ruminiclostridium6
was negatively associated with SLE. Based on the genome-wide statistical significance threshold, the results showed that
Actinobacteria
might reduce the SLE risk. However, Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) detected significant horizontal pleiotropy between the instrumental variables of
Ruminiclostridium6
and outcome. This study support that there are beneficial or detrimental causal effects of gut microbiome components on SLE risk.
The production of photo‐switchable molecular nanomagnets with substantial coercivity, which is indispensable for information storage and process applications, is challenging. Introducing ...photo‐responsive spin‐crossover units provides a feasible means of controlling the magnetic anisotropy, interactions, and overall nanomagnet properties. Herein, we report a cyanide‐bridged chain 1⋅12H2O ({(PzTp)FeIII(CN)32FeII(Pmat)2}n⋅12 H2O) generated by linking the FeII‐based spin‐crossover unit with the (PzTp)Fe(CN)3− (PzTp: tetrakis(pyrazolyl)borate) building block in the presence of asymmetric ditopic ligand Pmat ((4‐pyridine‐4‐yl)methyleneamino‐1,2,4‐triazole). Structural characterization revealed that the introduction of this asymmetric ligand led to a distorted coordination environment of FeII ions, which were equatorially coordinated by four cyanide N atoms, and apically coordinated by one pyridine N atom and one triazole N atom. Upon 808‐nm light irradiation, 1⋅12H2O underwent photoinduced spin‐crossover and exhibited single‐chain magnet behavior with a coercive field of up to 1.3 T. This represents a 3d‐based photoinduced single‐chain magnet exhibiting pronounced hysteresis.
A light‐induced spin‐crossover switchable single‐chain magnet was discovered in an asymmetric ditopic ligand‐containing cyanide‐bridged compound. A photoinduced opening hysteresis with the highest coercive field of 1.3 T was realized in pure 3d metal‐based molecular magnets.
On the basis of Covid-19-induced pulmonary pathological and vascular changes, we hypothesize that the anti-vascular endothelial growth factor (VEGF) drug bevacizumab might be beneficial for treating ...Covid-19 patients. From Feb 15 to April 5, 2020, we conducted a single-arm trial (NCT04275414) and recruited 26 patients from 2-centers (China and Italy) with severe Covid-19, with respiratory rate ≥30 times/min, oxygen saturation ≤93% with ambient air, or partial arterial oxygen pressure to fraction of inspiration O
ratio (PaO
/FiO
) >100 mmHg and ≤300 mmHg, and diffuse pneumonia confirmed by chest imaging. Followed up for 28 days. Among these, bevacizumab plus standard care markedly improves the PaO
/FiO
ratios at days 1 and 7. By day 28, 24 (92%) patients show improvement in oxygen-support status, 17 (65%) patients are discharged, and none show worsen oxygen-support status nor die. Significant reduction of lesion areas/ratios are shown in chest computed tomography (CT) or X-ray within 7 days. Of 14 patients with fever, body temperature normalizes within 72 h in 13 (93%) patients. Relative to comparable controls, bevacizumab shows clinical efficacy by improving oxygenation and shortening oxygen-support duration. Our findings suggest bevacizumab plus standard care is highly beneficial for patients with severe Covid-19. Randomized controlled trial is warranted.
Stimulating tunable room-temperature phosphorescence (RTP) is still a challenge in photochromic systems, which is vital for multifunctional coordination materials. Herein, we synthesized two new ...photochromic chain complexes through self-assembly of the nonphotochromic 1,3,5-tris(4-pyridyl)benzene ligand, diphosphonate, and Ln(III) ions (
for Ln(III) = Dy and
for Ln(III) = Gd). Both compounds showed fast photoresponses with the color turning from yellow to dark gray with a reversible decoloration by heating or storage in the dark. The electron transfer photochromic behavior with the generated stable radicals was further confirmed by the room-temperature UV-vis and electron paramagnetic resonance spectra. Furthermore, via tuning the generation and disappearance of stable radicals, reversible room-temperature fluorescence and phosphorescence for both compounds were switched by light irradiation and a thermal treatment, with an enhanced intensity for RTP and a decrease in fluorescence during the duration of Xe-lamp light irradiation. This work provides a new strategy that photogenerated radicals could promote and enhance RTP properties in functional materials.
•The previous literature about closest targets satisfying (strong) monotonicity is mostly based on complicated multi-stage procedure.•A simple MILP is proposed to find the closest targets that ...satisfies strong monotonicity.•The proposed approaches are applied to industrial production processes of China.
The benchmarking information targets based on Data envelopment analysis (DEA) are commonly classified into two groups: the farthest targets and the closest targets. Many methods have been introduced to derive the closest projection to the strongly efficienct frontier, most of them merely based on the computation of closest efficient targets. Although there are several measures that satisfy a set of interesting properties from an economic and mathematical point of view, they are based on output-oriented models with a multi-stage procedure and cannot be extended easily to the situation of non-orientation, or they are mostly based on a conceptual framework which could not be solved easily. In this paper, we provide an easy, well-defined efficiency measure based on non-oriented closest targets that satisfies strong monotonicity and that is calculated by a simple mixed integer linear program (MILP). A real case of industrial production processes of 30 provincial level regions in mainland China was analyzed to verify the applicability of our proposed approach.
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