Molecular chirality is a cornerstone of modern chemistry and it has a profound impact on biological activity, chemical reactivity and physical property. Developing asymmetric synthesis methods to efficiently and preci...
Molecular chirality is a cornerstone of modern chemistry and it has a profound impact on biological activity, chemical reactivity and physical property. Developing asymmetric synthesis methods to efficiently and precisely produce chiral molecules remains a challenging issue in organic chemistry. In recent years, transition-metal-catalyzed enantioselective C–H activation has emerged as an efficient strategy for the rapid access to valuable chiral compounds from readily available feedstocks in an atom-and step-economic manner. Here we report a rhodium(III)-catalyzed C–H activation/annulation of ketones with alkynes. This method features mild conditions, wide substrate scope, and perfect atom economy, affording a series of chiral tertiary indenols in excellent yields and enantioselectivity(up to 98% yield and 99% ee). Combined experimental and computational studies revealed the turnover-limiting step of the reaction and the origins of enantioselectivity and regioselectivity.
Background: Mesh exposure after surgery continues to be a clinical challenge for urogynecological surgeons. The purpose of this study was to explore the risk factors for polypropylene (PP) mesh exposure after trans...
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Background: Mesh exposure after surgery continues to be a clinical challenge for urogynecological surgeons. The purpose of this study was to explore the risk factors for polypropylene (PP) mesh exposure after transvaginal mesh (TVM) surgery. Methods: This study included 195 patients with advanced pelvic organ prolapse (POP), who underwent TVM from January 2004 to December 2012 at the First Affiliated Hospital of Chinese PLA General Hospital. Clinical data were evaluated including patient's demography, TVM type, concomitant procedures, operation time, blood loss, postoperative morbidity, and mesh exposure. Mesh exposure was identified through postoperative vaginal examination. Statistical analysis was performed to identify risk factors for mesh exposure. Results: Two-hundred and nine transvaginal PP meshes were placed, including 194 in the mltefior wall and 15 in the posterior wall. Concomitant tension-free vaginal tape was pertbrmed in 61 cases. The mean follow-up time was 35.1 :e 23.6 months. PP mesh exposure was identified in 32 cases (16.4%), with 31 in the anterior wall and 1 in the posterior wall. Significant difference was found in operating time and concomitant procedures between exposed and nonexposed groups (F = 7.443, P = 0.007; F = 4.307, P = 0.039, respectively). Binary logistic regression revealed that the number of concomitant procedures and operation time were risk factors for mesh exposure (P = 0.001, P = 0.043). Conclusion: Concomitant procedures and increased operating time increase the risk for postoperative mesh exposure in patients undergoing TVM surgery for POP.
An online subsection cooling method for hot rolling silicon steel was designed to achieve local adjustment of transverse roll ***,it was able to meet the requirements of edge drop of the strip by using the features of...
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An online subsection cooling method for hot rolling silicon steel was designed to achieve local adjustment of transverse roll ***,it was able to meet the requirements of edge drop of the strip by using the features of online thermal ***,after the new subsection spray beam was installed at the exit of mill,the special local cooling rules were analyzed for altering the thermal crown of roll according to rolling process ***,the dynamic impact of subsection cooling on the local thermal crown could just be obtained according to the measured ***,the heat transfer coefficient was determined by different subsection cooling curves under varied rolling ***,the rolling rhythm and variable conditions were important dynamic factors of transient roll temperature in practical rolling ***,real-time calculation and presetting of the thermal crown were carried out to maximize special requirements of load roll gap on local strip *** this new method,the transient temperature and the thermal crown of roll could be quantitatively controlled *** the practical results showed that the predicted temperature was able to match the measured value by more than 95%.Meanwhile,the adjustable range of thermal crown increased by more than 2.5 ***,the qualification rate of strip edge crown has increased from the original 30%to over 70%.
Mitogen-activated protein kinases(MPKs)play essential roles in guard cell signaling,but whether MPK cascades participate in guard cell ethylene signaling and interact with hydrogen peroxide(H2O2),nitric oxide(NO),and ...
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Mitogen-activated protein kinases(MPKs)play essential roles in guard cell signaling,but whether MPK cascades participate in guard cell ethylene signaling and interact with hydrogen peroxide(H2O2),nitric oxide(NO),and ethylene-signaling components remain ***,we report that ethylene activated MPK3 and MPK6 in the leaves of wild-type Arabidopsis thaliana as well as ethylene insensitive2(ein2),ein3,nitrate reductase1(nia1),and nia2 mutants,but this effect was impaired in ethylene response1(etr1),nicotinamide adenine dinucleotide phosphate oxidase AtrbohF,mpk kinase1(mkk1),and mkk3 *** contrast,the constitutive triple response1(ctr1)mutant had constitutively active MPK3 and *** two-hybrid,bimolecular fluorescence complementation,and pull-down assays indicated that MPK3 and MPK6 physically interacted with MKK1,MKK3,and the C-terminal region of EIN2(EIN2 CEND).mkk1,mkk3,mpk3,and mpk6 mutants had typical levels of ethylene-induced H2O2 generation but impaired ethylene-induced EIN2 CEND cleavage and nuclear translocation,EIN3 protein accumulation,NO production in guard cells,and stomatal *** results show that the MKK1/3–MPK3/6 cascade mediates ethylene-induced stomatal closure by functioning downstream of ETR1,CTR1,and H2O2 to interact with EIN2,thereby promoting EIN3 accumulation and EIN3-dependent NO production in guard cells.
Photovoltaic (PV) modules, as essential components of solar power generation systems, significantly influence unitpower generation *** service life of these modules directly affects these costs. Over time, the perform...
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Photovoltaic (PV) modules, as essential components of solar power generation systems, significantly influence unitpower generation *** service life of these modules directly affects these costs. Over time, the performanceof PV modules gradually declines due to internal degradation and external environmental *** cumulativedegradation impacts the overall reliability of photovoltaic power generation. This study addresses the complexdegradation process of PV modules by developing a two-stage Wiener process model. This approach accountsfor the distinct phases of degradation resulting from module aging and environmental influences. A powerdegradation model based on the two-stage Wiener process is constructed to describe individual differences inmodule degradation processes. To estimate the model parameters, a combination of the Expectation-Maximization(EM) algorithm and the Bayesian method is employed. Furthermore, the Schwarz Information Criterion (SIC) isutilized to identify critical change points in PV module degradation trajectories. To validate the universality andeffectiveness of the proposed method, a comparative analysis is conducted against other established life predictiontechniques for PV modules.
Let X={X(t),t∈R+} be a centered space anisotropic Gaussian process values in R^(d) with non-stationary increments,whose components are independent but may not be identically *** certain conditions,then almost surely ...
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Let X={X(t),t∈R+} be a centered space anisotropic Gaussian process values in R^(d) with non-stationary increments,whose components are independent but may not be identically *** certain conditions,then almost surely c_(1)≤ϕ-m(X([0,1]))≤c_(2),where ϕ denotes the exact Hausdorff measure associated with function ϕ(s)=s1/α_(k)+Σ_(i=1)k(1-αi/αk)log log 1/s for some 1≤k≤d,(α_(1),…,α_(d))∈(0,1]^(d).We also obtain the exact Hausdorff measure of the graph of X on[0,1].
Seawater electrolysis is a promising approach for sustainable energy without relying on precious ***,the large-scale seawater electrolysis is hindered by low catalytic efficiency and severe anode corrosion caused by t...
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Seawater electrolysis is a promising approach for sustainable energy without relying on precious ***,the large-scale seawater electrolysis is hindered by low catalytic efficiency and severe anode corrosion caused by the harmful *** contrast to the oxygen evolution reaction (OER)and chlorin ion oxidation reaction (ClOR),glycerol oxidation reaction (GOR) is more thermodynamically and kinetically favorable ***,a Ru doping cobalt phosphide (Ru-CoP_(2)) is proposed as a robust bifunctional electrocatalyst for seawater electrolysis and GOR,for the concurrent productions of hydrogen and value-added *** in situ and ex situ characterization analyses demonstrated that Ru doping featured in the dynamic reconstruction process from Ru-CoP_(2)to Ru-CoOOH,accounting for the superior GOR *** coupling GOR with hydrogen evolution was realized by employing Ru-CoP_(2)as both anode and cathode,requiring only a low voltage of 1.43 V at 100 mA cm^(-2),which was 250 m V lower than that in alkaline *** work guides the design of bifunctional electrocatalysts for energy-efficient seawater electrolysis coupled with biomass resource upcycling.
Wing dimorphism is regarded as an important phenotypic plasticity involved in the migration and reproduction of aphids. However, the signal transduction and regulatory mechanism of wing dimorphism in aphids are still ...
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Wing dimorphism is regarded as an important phenotypic plasticity involved in the migration and reproduction of aphids. However, the signal transduction and regulatory mechanism of wing dimorphism in aphids are still unclear. Herein, the optimal environmental conditions were first explored for inducing winged offspring of green peach aphid, and the short photoperiod was the most important environmental cue to regulate wing dimorphism. Compared to 16 L:8 D photoperiod, the proportion of winged offspring increased to 90% under 8 L:16 D photoperiod. Subsequently, 5 differentially expressed microRNAs (miRNAs) in aphids treated with long and short photoperiods were identified using small RNA sequencing, and a novel miR-3040 was identified as a vital miRNA involved in photoperiod-mediated wing dimorphism. More specifically, the inhibition of miR-3040 expression could reduce the proportion of winged offspring induced by short photoperiod, whereas its activation increased the proportion of winged offspring under long photoperiod. Meanwhile, the expression level of miR-3040 in winged aphids was about 2.5 times that of wingless aphids, and the activation or inhibition of miR-3040 expression could cause wing deformity, revealing the dual-role regulator of miR-3040 in wing dimorphism and wing development. In summary, the current study identified the key environmental cue for wing dimorphism in green peach aphid, and the first to demonstrate the dual-role regulator of miR-3040 in photoperiod-mediated wing dimorphism and wing development.
The early trans-Eurasian exchange and its influence on the dynamics of human-land relationships is an emerging topic involving multiple *** southwestern part of the Eastern European Plain was a key hub for early East-...
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The early trans-Eurasian exchange and its influence on the dynamics of human-land relationships is an emerging topic involving multiple *** southwestern part of the Eastern European Plain was a key hub for early East-West *** millet,a crop domesticated in China,was introduced into the region about 3,600 years ago,significantly earlier than in other parts of *** research employs systematic archaeobotanical flotation and AMS radiocarbon dating at two sites in Romania:Baia-?n Muchie and Dobrov??.The findings demonstrate that broomcorn millet cultivation in this region has persisted for over 2,000 years,exhibiting significant diachronic *** was most intensively utilized during the Late Bronze Age to the Early Iron Age(1200–800 BC)and the Late Roman Empire(AD 250–400),periods which were characterized by rapid climatic *** may have been cultivated as a“disaster relief”crop to mitigate the challenges posed by extreme drought and *** millet grains from the study area are similar in dimensions to those reported in East Asia;however,grains from the Romanian sites are thinner and *** route traversing the Caucasus and the northern Black Sea likely served as a key passage through which millet entered Europe from West *** research provides valuable data on the chronology of millet cultivation in the SW Eastern European Plain and enhances our understanding of early East-West exchanges and their impact on human-environment interactions in critical regions.
High-entropy alloys(HEAs) have emerged as promising candidates to replace traditional precious metal catalysts,owing to their unique chemical and physical *** review commences by revisiting the fundamental concepts of...
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High-entropy alloys(HEAs) have emerged as promising candidates to replace traditional precious metal catalysts,owing to their unique chemical and physical *** review commences by revisiting the fundamental concepts of HEAs,including their synthesis methods and structural control strategies in *** underscores the critical role of meticulously manipulating both macroscopic and microscopic structures of the HEAs to optimize their catalytic performance.A deep understanding of the structure-activity relationship in HEAs across various configurations is pivotal in developing more effective *** review methodically encapsulates the research progress of structural control strategies for HEAs in achieving efficient energy conversion,with the aim of gaining a better understanding of the relationship between structure and *** review concludes by summarizing the current achievements and challenges,and suggestions for potential future directions of HEAs in the fields of energy conversion and environmental purification.
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