Abstract
The growth law, electronic properties and spectra of (
n
= 2–18;
λ
= 0, ±1) clusters have been examined by density functional theory (DFT) and an unbiased structure prediction method. ...Extensive geometry optimizations have been executed and show that the global minimum structures of clusters have a distinct growth law when n is 8–18. For
n
= 8–13 and 14–18, the iron atoms grow around a decahedral and icosahedral iron cluster core, respectively. Based on the present ground states, the calculated electronic parameters are in line with the experimental values. The thermal stability of charged iron cluster is higher than that of neutral iron cluster. The octahedral and icosahedral clusters are more stable than their neighbors. The former has low chemical activity and may be a superatom. The magnetic moment of Fe atom weakens in the cluster. The UV spectra, photoelectron spectra (PES) and infrared and Raman spectra of the clusters have been predicted and the global minimum structures of the clusters are determined by comparing the theoretical PES with the experimental results.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Photoelectrochemical (PEC) cell is a meaningful way to fulfil carbon dioxide (CO2) conversion to value-added chemicals, but the exploration of ideal photocathode materials with high photo-conversion ...efficiency remains a challenge. Herein, porous ZnO@ZnSe core/shell nanosheet array on fluorine doped-tin oxide (FTO) glass is synthesized via dissolution-recrystallization mechanism by using ZnO nanosheet array as the template, and is used for the first time as the photocathode for PEC reduction of CO2. The effect of ZnSe loading amount on PEC responses of composite electrode is investigated in detail. Under the irradiation of visible light, the optimized ZnO@ZnSe photocathode exhibits onset potentials at 0.39 V (vs. RHE) in CO2-purged 0.5 M NaHCO3 solution and achieves the photocurrent of 1.17 mA cm-2 at −0.11 V (vs. RHE). Interestingly, the competitive H2 evolution reaction can be suppressed effectively and thereby the selectivity for CO2 reduction reactions especially for CO formation is increased when the applied voltage became more negative. The faradic efficiency of CO increases dramatically from 4.2% at 0.2 V to 52.9% at −0.4 V and the electron selectivity for CO2 reduction increases from 70.1% to 96.6% accordingly. These results demonstrate that ZnO@ZnSe composite electrode can work as promising photocathode for efficient CO2 reduction.
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•ZnSe based photocathode is reported for PEC reduction of CO2 for the first time.•Porous ZnO@ZnSe core/shell nanosheet array electrode can be prepared controllably.•The composite photocathode exhibits superior selectivity for CO2 reduction than H2.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Objective
To investigate the effects of age, body mass index (BMI), bone mineral density (BMD), and levels of serum 25‐hydroxyvitamin D (25OHD) on hip fracture on the condition of the bone density of ...femoral neck having reached the threshold of osteoporosis.
Methods
A total of 252 postmenopausal women patients, whose bone density had reached the threshold of osteoporosis and age ≥50 years (50–98 years), collected from the Second Affiliated Hospital of Fujian Medical University from January 2015 to December 2018, were performed by retrospective analysis. According to whether or not they had a hip fracture, including femoral neck fracture or intertrochanteric fracture, the patients were divided into two groups, including 117 cases (50–84 years old) in the non‐hip fracture group and 135 cases (57–98 years old) in the hip fracture group. BMD was measured by Hologic Discovery A DXA bone mineral densitometer. Levels of serum 25OHD were detected by ROCHE detection instrument. Comparisons of age, BMI, bone density of femoral neck, and levels of serum 25OHD between the two groups were performed by using the Student's t‐test. Furthermore, the statistically significant factors were analyzed by multiple regression analysis to investigate the independent risk factors of hip fracture.
Results
The group without hip fracture: 117 cases; average age: 67.4 ± 8.5 years; BMI: 22.3 ± 3.2 kg/m2; bone density of femoral neck: (0.504 ± 0.067) g/cm2; T‐value of femoral neck: −3.1 ± 0.6; levels of serum 25OHD: (24.9 ± 8.5) ng/mL. The group with brittle hip fracture: 135 cases; average age: 80.7 ± 7.6 years; BMI: 20.3 ± 3.5 kg/m2; bone density of femoral neck: (0.426 ± 0.077) g/cm2; T‐value of femoral neck: −3.8 ± 0.7; levels of serum 25OHD: (15.9 ± 8.9) ng/mL. Age, BMI, bone density of femoral neck, and 25OHD level of the group without hip fracture were markedly lower than hip fracture group (P < 0.05). The results of logistic regression analysis suggested that age, bone density of femoral neck, and levels of serum 25OHD were independent risk factors for fragile hip fracture on the condition of the bone density of femoral neck having reached the threshold of osteoporosis.
Conclusion
Higher age, lower levels of bone density and 25OHD are the main risk factors of hip fracture on the condition of the bone density of femoral neck having reached the threshold of osteoporosis.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
This study aims to investigate the effects of threonine (Thr) on immunoregulation
and
of teleost grass carp (
). Juveniles (9.53 ± 0.02 g) were reared for 8 weeks with respective Thr diet (3.99, ...7.70, 10.72, 14.10, 17.96, and 21.66 g/kg) and then challenged with
for
study. Macrophages isolated from head kidney were treated
for 48 h with L-Thr (0, 0.5, 1.0, 2.0, 4.0, and 8.0 mM) after 6 h of lipopolysaccharide induction. The results showed that, compared with Thr deficiency (3.99 g/kg), the optimal dietary Thr (14.10g/kg) affected the immunocyte activation in the head kidney (HK) and spleen (SP) by downregulating the mRNA expressions of MHC-II and upregulating CD4 (not CD8), and it mediated the innate immune by enhancing the activities of lysozyme (LZ), acid phosphatase content of complement 3 (C3) and C4, increasing the mRNA abundances of hepcidin, liver expressed antimicrobial peptide-2A (LEAP-2A), LEAP-2B, β-defensin1, downregulating tumor necrosis factor α (TNF-α), IL-6, IL-1β, IL-12p35, IL-12p40, IL-17AF1, and IL-17D partly by attenuating RORγ1 transcriptional factor and nuclear factor kappa B p65 (NF-κBp65) signaling cascades IKKβ/IκBα/NF-κBp65 and upregulating transforming growth factor β1 (TGF-β1), IL-4/13A, -4/13B, IL-10, and IL-22 partly by GATA-3. Besides these, the optimal dietary Thr regulated the adaptive immune by upregulating the mRNAs of immunoglobulin M (IgM) and IgZ (not IgD). Moreover, 2 mM Thr downregulated
the mRNA abundances of colony stimulating factor-1, inducible nitric oxide synthase, mannose receptor 1, matrix metalloproteinase2 (MMP-2), and MMP-9 significantly (
< 0.05), indicating that Thr could attenuate the M1-type macrophages' activation. Moreover, L-Thr downregulated the mRNA transcripts of TNF-α, IL-6, and IL-1β associated with impairing the SOCS1/STAT1 signaling and upregulated IL-10 and TGF-β1 partly by accentuating the SOCS3/STAT3 pathway. The above-mentioned observations suggested that Thr improved the immune status in the immune organs of fish by enhancing the immune defense and mediating the inflammation process. Finally, based on the immune indices of LZ activity in HK and C3 content in SP, the optimal Thr for immune enhancement in juvenile grass carp (9.53-53.43 g) was determined to be 15.70 g/kg diet (4.85 g/100 g protein) and 14.49 g/kg diet (4.47 g/100 g protein), respectively.
Corrosion of the laser additive manufactured (LAM) steel attracts increasing attentions. In this work, plasma nitriding was carried out to improve the strength and corrosion resistance of LAM 18Ni300 ...maraging steel at the same time. Nitriding of the as-fabricated sample obtains a heterogeneous nitriding structure with typical LAM dendrite boundaries. Nanosized N-rich grains and associated N-depleted grains were found along the LAM dendrite boundaries, which are beneficial for pitting resistance. Moreover, the corrosion reaction of the nitrided surface is confirmed as γ′/γ + O → MeO(N) + Me+, (Me = Fe, Co, Ni, Mo).
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•Corrosion resistance of LAM maraging steel are improved by two nitriding structures.•Corrosion responses of the two nitriding structures are different.•LAM dendrite boundaries are beneficial for pitting resistance of nitrided surface.•The corrosion reactions of nitrides are confirmed by HRTEM.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The development of an all-inorganic lead-free perovskite nanocrystal is of crucial importance to solve the instability and lead toxicity of organic-inorganic lead hybrid perovskites. Herein, ...single-layered Cs4CuSb2Cl12 nanocrystals (NCs) with a narrow band gap of 1.6 eV were prepared for the first time via an ultrasonic exfoliation technique. This powerful top-down method was further generalized to synthesize a class of lead-free perovskite (Cs3Bi2X9 and Cs3Sb2X9) NCs. The experimental and theoretical studies revealed that not only inter-layer van der Waals forces but also in-plane chemical bonds played a critical role in the exfoliation process. Specifically, smaller uniform-sized NCs were observed for Cs4CuSb2Cl12 (∼3 nm) as compared to those for Cs3Sb2Cl9 (∼20 nm) although both Cs4CuSb2Cl12 and Cs3Sb2Cl9 exhibited a similar exfoliation energy (∼0.310 J m-2). This can be ascribed to the weaker in-plane chemical bonds of Cu-Cl (2.808 Å) and Sb-Cl (2.924 Å) in Cs4CuSb2Cl12 than the uniform Cl-Sb bond (2.69 Å) in Cs3Sb2Cl9 that allow for an easier exfoliation process. In addition, exfoliation of the Cs4CuSb2Cl12 microcrystal into NCs results in an indirect-to-direct bandgap transition and a reduced electron effective mass, which provides a rapid and steady photoelectrochemical response, demonstrating that Cs4CuSb2Cl12 NCs are a promising candidate for optoelectronic applications.
In this report, a novel zero-dimensional CsPbBr3 nanocrystal (CsPbBr3 NC)/two-dimensional Pd nanosheet (Pd NS) composite photocatalyst is prepared to afford efficient and stable photocatalytic ...gaseous CO2 reduction in the presence of H2O vapor under visible light illumination. Pd NS herein acts as an electron reservoir to quickly separate the electron–hole pairs in CsPbBr3 NC through a Schottky contact, and provides an ideal site for CO2 reduction reactions. A highest electron consumption rate of 33.79 μmol g–1 h–1 is achieved by the CsPbBr3 NC/Pd NS composite, which corresponds to a 2.43-fold enhancement over pristine CsPbBr3 NC (9.86 μmol g–1 h–1), thus providing a practical and universal solution for the halide perovskite materials to boost the photocatalytic performance through semiconductor/metal design.
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IJS, KILJ, NUK, PNG, UL, UM
•Using the historical load data of other related regions, the load forecasting of data-poor regions is realized.•The latent features of load data are extracted by the improved K-means and MIFS, which ...can improve the fitting ability of forecasting model.•The BO-XGBoost method guarantees the generalization performance of the load forecasting model.•Two cases demonstrate the prediction performance of K-MIFS-XGBoost and transfer-learning forecasting framework is superior to other transfer learning and non-transfer learning methods.
Sufficient historical power load data is crucial for establishing accurate load forecasting model. However, in newly developed areas or areas with relatively backward power metering infrastructure, historical data are often very limited. With a focus on this problem, a transfer forecasting framework for short-term loads is proposed in this paper. To improve the fitting ability of the forecasting model, a modified K-means method combined with mutual information feature selection (MIFS) algorithm is proposed to extract the hidden features of different seasonal loads. Then with corresponding load data (source area), a Bayesian hyperparameter optimization approach is proposed, to establish the optimal extreme gradient boosting (XGBoost) load forecasting model. To solve the problem of limited historical load data (target area), we transfer the source area model to the target area by fine-tuning model parameters and weighting holiday samples. For demonstration, two case studies, with power load datasets in two regions of China and GEFcom2012 datasets, are performed. The results of comparative experiments show that the forecasting error can be reduced by a large margin with the knowledge learned from other areas.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Automated human action recognition has the potential to play an important role in public security, for example, in relation to the multiview surveillance videos taken in public places, such as train ...stations or airports. This paper compares three practical, reliable, and generic systems for multiview video-based human action recognition, namely, the nearest neighbor classifier, Gaussian mixture model classifier, and the nearest mean classifier. To describe the different actions performed in different views, view-invariant features are proposed to address multiview action recognition. These features are obtained by extracting the holistic features from different temporal scales which are modeled as points of interest which represent the global spatial-temporal distribution. Experiments and cross-data testing are conducted on the KTH, WEIZMANN, and MuHAVi datasets. The system does not need to be retrained when scenarios are changed which means the trained database can be applied in a wide variety of environments, such as view angle or background changes. The experiment results show that the proposed approach outperforms the existing methods on the KTH and WEIZMANN datasets.
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