113 research outputs found

    Lipophilic M(α,α′-OC5H11)8phthalocyanines (M = H2 and Ni(II)): synthesis, electronic structure, and their utility for highly efficient carbonyl reductions

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    A lipophilic and electron-rich phthalocyanine (α,α′-n-OC5H11)8-H2Pc and its nickel(II) complex (α,α′-n-OC5H11)8-Ni(II)Pc have been synthesized and characterized. Detailed analyses of the electronic structure were carried out by spectroscopy, electrochemistry, spectroelectrochemistry, and TD-DFT calculations. A series of experiments demonstrate that the (α,α′-n-OC5H11)8-Ni(II)Pc complex can be used as a catalyst for highly efficient carbonyl reductions.Original publication is available at http://dx.doi.org/10.1039/C5DT03256

    Comprehensive ab initio study of effects of alloying elements on generalized stacking fault energies of Ni and Ni3_3Al

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    Excellent high-temperature mechanical properties of Ni-based single crystal superalloys (NSCSs) are attributed to the yield strength anomaly of Ni3_{3}Al that is intimately related to generalized stacking fault energies (GSFEs). Therefore, clarifying the effects of alloying elements on the GSFEs is of great significance for alloys design. Here, by means of ab initio density functional theory calculations, we systematically calculated the GSFEs of different slip systems of Ni and Ni3_{3}Al without and with alloying elements using the alias shear method. We obtained that for Ni, except for magnetic elements Mn, Fe, and Co, most of alloying elements decrease the unstable stacking fault energy (γusf\gamma_{usf}) of the [011ˉ](111)[01\bar{1}](111) and [112ˉ](111)[11\bar{2}](111) slip systems and also decrease the stable stacking fault energy (γsf\gamma_{sf}) of the [112ˉ](111)[11\bar{2}](111) slip system. For Ni3_{3}Al, most of alloying elements in groups IIIB-VIIB show a strong Al site preference. Except for Mn and Fe, the elements in groups VB-VIIB and the first column of group VIII increase the values of γusf\gamma_{usf} of different slip systems of Ni3_{3}Al. On the other hand, the elements in groups IIIB-VIIB also increase the value of γsf\gamma_{sf}. We found that Re is an excellent strengthening alloying element that significantly increases the slip barrier of the tailing slip process for Ni, and also enhances the slip barrier of the leading slip process of three slip systems for Ni3_{3}Al. W and Mo exhibit similar effects as Re. We predicted that Os, Ru, and Ir are good strengthening alloying elements as well, since they show the strengthening effects on both the leading and tailing slip process for Ni and Ni3_{3}Al

    Study on Parameter Optimization for Support Vector Regression in Solving the Inverse ECG Problem

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    The typical inverse ECG problem is to noninvasively reconstruct the transmembrane potentials (TMPs) from body surface potentials (BSPs). In the study, the inverse ECG problem can be treated as a regression problem with multi-inputs (body surface potentials) and multi-outputs (transmembrane potentials), which can be solved by the support vector regression (SVR) method. In order to obtain an effective SVR model with optimal regression accuracy and generalization performance, the hyperparameters of SVR must be set carefully. Three different optimization methods, that is, genetic algorithm (GA), differential evolution (DE) algorithm, and particle swarm optimization (PSO), are proposed to determine optimal hyperparameters of the SVR model. In this paper, we attempt to investigate which one is the most effective way in reconstructing the cardiac TMPs from BSPs, and a full comparison of their performances is also provided. The experimental results show that these three optimization methods are well performed in finding the proper parameters of SVR and can yield good generalization performance in solving the inverse ECG problem. Moreover, compared with DE and GA, PSO algorithm is more efficient in parameters optimization and performs better in solving the inverse ECG problem, leading to a more accurate reconstruction of the TMPs

    Temporal Specification and Bilaterality of Human Neocortical Topographic Gene Expression

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    SummaryTranscriptional events involved in the development of human cerebral neocortex are poorly understood. Here, we analyzed the temporal dynamics and laterality of gene expression in human and macaque monkey neocortex. We found that interareal differences exhibit a temporal hourglass pattern, dividing the human neocortical development into three major phases. The first phase, corresponding to prenatal development, is characterized by the highest number of differential expressed genes among areas and gradient-like expression patterns, including those that are different between human and macaque. The second, preadolescent phase, is characterized by lesser interareal expression differences and by an increased synchronization of areal transcriptomes. During the third phase, from adolescence onward, differential expression among areas increases again driven predominantly by a subset of areas, without obvious gradient-like patterns. Analyses of left-right gene expression revealed population-level global symmetry throughout the fetal and postnatal time span. Thus, human neocortical topographic gene expression is temporally specified and globally symmetric

    Analysis of occupational identity among family doctor teams and its influencing factors in Chengdu

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    BackgroundThe contracted family doctor services are the embodiment of the implementation of the new medical reform policy, and the transformation of the grass-roots health service mode. Studies have proved that the occupational stress in medical staff was at a high level. The enhancement of professional identity will contribute to strengthen team building,alleviate job burnout, and reduce turnover intention of family doctors. ObjectiveTo investigate the current situation of occupational identity among family doctor teams in Chengdu, to examine potential influencing factors of occupational identity, and to provide a reference for promoting career development and team building of family doctor teams. MethodsMulti-stage random cluster sampling was adopted to enroll study participants form 46 primary healthcare centers where family doctor contract services were implemented among 23 districts and counties in Chengdu between March 4 and 26, 2021. A total of 2 681 family doctors participated in this survey. A self-reported survey was conducted to collect participants' demographic and occupational data. The Effort-Reward Imbalance (ERI)questionnaire was implemented to assess occupational stress. The Professional Identity Scale was used to appraise occupational identity. ResultsA total of 2 327 valid questionnaires were collected, with a valid recovery rate of 86.80%, involving 1 715 females (73.7%) and 612 males (26.3%), with dominant age groups of 26−35 years (43.3%) and 36−45 years (30.4%), a high proportion of being married (82.8%), having college (36.0%) and undergraduate (47.3%) education, a high proportion of primary titles (66.0%) and informal work contract (66.1%). About 88.7% of family doctor team workers reported occupational stress. The average score of occupational identity was (3.68±0.62) points. There were significant differences in occupational identity scores among different professional title, work contract, working years in medical institutions, income, and effort/reward ratio (EER) groups (P < 0.05). ERR was negatively correlated with occupational identity (rs=−0.495, P<0.05). The multiple regression model showed that occupational identity score in the non-staffed participants was lower than the score in the staffed ones (OR=0.429, 95%CI: 0.299−0.825). The occupational identity score in the participants having associate senior title or above was higher than in without professional title (OR=1.424, 95%CI: 1.194−2.328). The longer the working years, the higher the occupational identity score among the participants. The score of the more than 20 working years group was 1.820 times that of the less than 5 working years group (95%CI: 1.342−2.543). The higher the income, the higher the occupational identity score. The score of the 9001−12000 yuan per month group was 1.977 times that of the 1000−3000 yuan per month group (95%CI: 0.811−9.696) , and the score of the more than 12000 yuan per month group was 2.283 times that of the 1000−3000 yuan per month group (95%CI: 1.199−10.267). ConclusionThe family doctor team workers generally report occupational stress, and their occupational identity is at a medium level in Chengdu. Relevant managers should implement intervention measures against the main influencing factors to reduce their work tension and improve their occupational identity

    Modulation of the optical properties of chiral porphyrin dimers by introducing bridged chiral amide-bonds

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    The d/l-enantiomers of a series of three Zn(II)tetraarylporphyrin dimers were synthesized and isolated by incorporating a bridging amide-bonded xanthene moiety at the para-position of one of the meso-aryl rings. The electronic structures and optical properties were modulated by incorporating chiral amino acid moieties into the amide-bonding moieties of the xanthene bridge that contain methyl, tolyl and 2-methylindole substituents. A cofacial dimer was formed in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) resulting in a significant red shift of the B band, due to a relative destabilization of the HOMO, which has large MO coefficients on the pyrrole nitrogens. The sign sequences observed in the B band region of the CD spectra due to the presence of the chiral amino acid moieties were modified due to this change in geometry. Significant CD intensity is also observed in the B band region of the CD spectra of anion radical species during in situ spectroelectrochemical measurements

    Porphyrin dimers with a bridging chiral amide-bonded benzo-moiety

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    The facile synthesis and characterization of four porphyrin dimers which introduced stereomeric centers with chiral amide-bonded para- and meta-disubstituted benzo-moiety is reported. Trends in the electronic structures and optical and redox properties are analyzed through a comparison with theoretical calculations to explore the effect of positional isomerism of the bridging benzene rings

    Computation and Data Driven Discovery of Topological Phononic Materials

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    © 2021, The Author(s). The discovery of topological quantum states marks a new chapter in both condensed matter physics and materials sciences. By analogy to spin electronic system, topological concepts have been extended into phonons, boosting the birth of topological phononics (TPs). Here, we present a high-throughput screening and data-driven approach to compute and evaluate TPs among over 10,000 real materials. We have discovered 5014 TP materials and grouped them into two main classes of Weyl and nodal-line (ring) TPs. We have clarified the physical mechanism for the occurrence of single Weyl, high degenerate Weyl, individual nodal-line (ring), nodal-link, nodal-chain, and nodal-net TPs in various materials and their mutual correlations. Among the phononic systems, we have predicted the hourglass nodal net TPs in TeO3, as well as the clean and single type-I Weyl TPs between the acoustic and optical branches in half-Heusler LiCaAs. In addition, we found that different types of TPs can coexist in many materials (such as ScZn). Their potential applications and experimental detections have been discussed. This work substantially increases the amount of TP materials, which enables an in-depth investigation of their structure-property relations and opens new avenues for future device design related to TPs

    Association of vitamin D deficiency and subclinical diabetic peripheral neuropathy in type 2 diabetes patients

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    BackgroundDiabetic peripheral neuropathy (DPN) contributes to disability and imposes heavy burdens, while subclinical DPN is lack of attention so far. We aimed to investigate the relationship between vitamin D and distinct subtypes of subclinical DPN in type 2 diabetes (T2DM) patients.MethodsThis cross-sectional study included 3629 T2DM inpatients who undertook nerve conduction study to detect subclinical DPN in Zhongshan Hospital between March 2012 and December 2019. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D (25(OH)D) level &lt; 50 nmol/L.Results1620 (44.6%) patients had subclinical DPN and they were further divided into subgroups: distal symmetric polyneuropathy (DSPN) (n=685), mononeuropathy (n=679) and radiculopathy (n=256). Compared with non-DPN, DPN group had significantly lower level of 25(OH)D (P &lt; 0.05). In DPN subtypes, only DSPN patients had significantly lower levels of 25(OH)D (36.18 ± 19.47 vs. 41.03 ± 18.47 nmol/L, P &lt; 0.001) and higher proportion of vitamin D deficiency (78.54% vs. 72.18%, P &lt; 0.001) than non-DPN. Vitamin D deficiency was associated with the increased prevalence of subclinical DPN [odds ratio (OR) 1.276, 95% confidence interval (CI) 1.086-1.501, P = 0.003] and DSPN [OR 1. 646, 95% CI 1.31-2.078, P &lt; 0.001], independent of sex, age, weight, blood pressure, glycosylated hemoglobin, T2DM duration, calcium, phosphorus, parathyroid hormone, lipids and renal function. The association between vitamin D deficiency and mononeuropathy or radiculopathy was not statistically significant. A negative linear association was observed between 25(OH)D and subclinical DSPN. Vitamin D deficiency maintained its significant association with subclinical DSPN in all age groups.ConclusionsVitamin D deficiency was independently associated with subclinical DSPN, rather than other DPN subtypes
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