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1.
Prev Med Rep ; 43: 102771, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38846155

RESUMO

Background:  Gallstone disease is one of the most common gastrointestinal disorders. Despite extensive research exploring the risk factors associated with gallstones, the association between depressive symptoms and gallstones remains inadequately understood. This study aimed to assess the association between depressive symptoms and the prevalence of gallstones among adults in the United States. Methods: In this study, a cross-sectional design utilized data from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2017 to 2020. The assessment of depressive symptoms was conducted through the utilization of the Patient Health Questionnaire-9 (PHQ-9), which assigns total scores ranging from 0 to 27. Participants with PHQ-9 scores equal to or exceeding 10 were categorized as having clinically relevant depressive symptoms. Multivariable adjusted logistic regression and subgroup analysis were used to assess the association between depressive symptoms and gallstone prevalence. Results: A total of 7,797 participants aged 20 years or older were enrolled in this study, of whom 835 had a self-reported history of gallstones. After multiple adjustments, each one-point increase in PHQ-9 scores was associated with a 5 % increase in the risk of gallstones (odds ratio [OR], 1.05; 95 % confidence interval [CI], 1.03, 1.07, P < 0.001). Compared to individuals with PHQ-9 scores < 10, participants with PHQ-9 total scores ≥ 10 exhibited a 79 % higher risk of gallstones (OR = 1.79, 95 % CI: 1.43, 2.23, P < 0.001). Conclusion: Depressive symptoms were associated with an elevated prevalence of gallstones. However, it is important to note that further validation through prospective cohort studies is warranted to confirm this finding.

2.
Sci Total Environ ; : 173512, 2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38815825

RESUMO

To clarify the wind-driven post-bloom dispersion range of Microcystis, which originally clustered on the water surface, an Individual-Based Model (IBM) of Microcystis movement considering the combined effects of wind and light was developed based on actual hydrodynamic data and Microcystis biomass. After calibrating the effects of hydrodynamics and light, 66 cases of short-term (within a week) post-bloom with satellite images from 2011 to 2017 were simulated. The results showed that there were three short-term post-bloom types: vertical reduction (VR), horizontal reduction (HR) and mixed reduction (MR). For VR type, the cyanobacterial bloom reduction rate was rapid (>160 km2/day), but the dispersion range of Microcystis was limited (<2 km/day), and a larger bloom area was likely to form in the original location when wind speed decreased. For HR type, the cyanobacterial bloom reduction rate was slow (<10 km2/day), but Microcystis exhibited a broad dispersion range (>4 km/day), often leading to smaller, thicker, and longer-lasting cyanobacterial blooms downwind, albeit with a lower probability of occurrence. The characteristics of MR lay between the two aforementioned types.

3.
Int J Surg ; 2024 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-38446844

RESUMO

BACKGROUND: The C-reactive protein/lymphocyte ratio (CLR) is a prognostic biomarker of various diseases. However, its significance in acute pancreatitis (AP) remains unknown. The main aim of this study was to investigate the association between the CLR and disease severity in patients with AP. METHODS: This cross-sectional study included 476 AP patients (mild acute pancreatitis (MAP), n =176; moderately severe acute pancreatitis (MSAP) and severe acute pancreatitis (SAP), n=300). The primary exposure of interest was the baseline CLR. The primary outcome was the incidence of moderate to severe AP. Multivariate logistic regression and restricted cubic spline analyses were performed to evaluate the association between the CLR and the incidence of moderate to severe AP. Receiver operating characteristic (ROC) analysis was conducted to assess the predictive efficacy, sensitivity, and specificity of CLR in predicting the incidence of moderate to severe AP. RESULTS: The mean age of the patients was 44±13.2 years, and 76.5% were male. The distribution of CLR was 31.6 (interquartile range, 4.5, 101.7). Moderate to severe AP occurred in 300 cases (63.0%). After multiple adjustments, CLR was independently associated with the incidence of moderate to severe AP (odds ratio [OR], 1.04; 95% confidence interval [CI], 1.03, 1.05; P< 0.001). A nonlinear relationship was found between CLR and the incidence of moderate to severe AP, with a threshold of approximately 45. The effect size and CI below and above the threshold value were 1.061 (1.033-1.089) and 1.014 (0.997-1.031), respectively. The area under the curve (AUC) for CLR was 87.577% (95% CI: 84.443% ~ 90.710%) with an optimal cut-off value of 30.835, resulting in a sensitivity of 73.7% and a specificity of 88.6%. CONCLUSIONS: There was a nonlinear relationship with a saturation effect between the CLR and the incidence of moderate to severe AP. The CLR measured within 24 h of admission may serve as a promising biomarker for predicting the emergence of moderate to severe AP, thereby providing a more scientifically grounded basis for preventing such cases. Nonetheless, further research is warranted to validate and strengthen these findings.

4.
Cancer Cell Int ; 24(1): 83, 2024 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-38402402

RESUMO

Apatinib was the first anti-angiogenic agent approved for treatment of metastatic gastric cancer (GC). However, the emergence of resistance was inevitable. Thus investigating new and valuable off-target effect of apatinib directly against cancer cells is of great significance. Here, we identified extra spindle pole bodies-like 1 (ESPL1) was responsible for apatinib resistance in GC cells through CRISPR genome-wide gain-of-function screening. Loss of function studies further showed that ESPL1 inhibition suppressed cell proliferation, migration and promoted apoptosis in vitro, and accordingly ESPL1 knockdown sensitized GC cells to apatinib. In addition, we found ESPL1 interacted with mouse double minute 2 (MDM2), a E3 ubiquitin protein ligase, and the combination of MDM2 siRNA with apatinib synergistically ameliorated the resistance induced by ESPL1 overexpression. In summary, our study indicated that ESPL1 played a critical role in apatinib resistance in GC cells. Inhibition of MDM2 could rescue the sensitivity of GC cells to apatinib and reverse ESPL1-mediated resistance.

5.
RSC Adv ; 14(10): 7124-7130, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38414987

RESUMO

Enhancement of the adsorption performance and recyclability of adsorbents is a crucial aspect of water treatment. Herein, we used one-dimensional porous boron nitride (PBN) as a carrier to load Fe3O4 nanoparticles for the preparation of Fe3O4 nanoparticles-functionalized porous boron nitride (Fe3O4/PBN) via a ball milling method. The high-energy ball milling promoted the creation of a negatively charged PBN surface and facilitated the uniform distribution of Fe3O4 nanoparticles on the surface of PBN. The adsorption performance of Fe3O4/PBN toward cationic dyes could be significantly improved while no enhancement was observed for anionic dyes. The great adsorption performance of Fe3O4/PBN is due to its surface functional groups and surface defects formed in the ball milling process. Moreover, the strong interaction force between Fe3O4/PBN and cationic dyes promotes rapid initial adsorption due to their negatively charged surface. Magnetic measurements demonstrated that Fe3O4/PBN is superparamagnetic. The composites with low loadings of Fe3O4 nanoparticles could be quickly separated from the aqueous solution under a low applied magnetic field, improving their recyclability. This work highlights the role of ball milling in improving the adsorption performance of Fe3O4/PBN and greatly promotes the practical application of Fe3O4/PBN in the field of environmental purification.

6.
Sci Adv ; 10(3): eadj6417, 2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-38232154

RESUMO

Utilization of in situ/operando methods with broad beams and localized probes has accelerated our understanding of fluid-surface interactions in recent decades. The closed-cell microchips based on silicon nitride (SiNx) are widely used as "nanoscale reactors" inside the high-vacuum electron microscopes. However, the field has been stalled by the high background scattering from encapsulation (typically ~100 nanometers) that severely limits the figures of merit for in situ performance. This adverse effect is particularly notorious for gas cell as the sealing membranes dominate the overall scattering, thereby blurring any meaningful signals and limiting the resolution. Herein, we show that by adopting the back-supporting strategy, encapsulating membrane can be reduced substantially, down to ~10 nanometers while maintaining structural resiliency. The systematic gas cell work demonstrates advantages in figures of merit for hitherto the highest spatial resolution and spectral visibility. Furthermore, this strategy can be broadly adopted into other types of microchips, thus having broader impact beyond the in situ/operando fields.

7.
Inorg Chem ; 63(2): 1188-1196, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38175718

RESUMO

Metal-organic frameworks (MOFs) with long persistent luminescence (LPL) have attracted extensive research attention from researchers due to their potential applications in information encryption, anticounterfeiting technology, and security logic. In contrast to short-lived fluorescent materials, LPL materials offer a visible response that can be easily distinguished by the naked eye, thereby facilitating a much clearer visualization. However, there are few reports on functional LPL MOF materials as probes. In this article, two amino-functional LPL MOFs (VB4-2D and VB4-1D) were synthesized. They both exhibited adjustable fluorescence and phosphorescence from blue to green and from cyan to green, respectively. Notably, the MOFs emitted bright and adjustable LPL upon the removal of the different radiation sources. The basic amino functional groups in the MOFs exhibited acid and ammonia sensitivity, and fluorescence and phosphorescence emission intensities can be burst and restored in two atmospheres, respectively, which can be cycled multiple times. Furthermore, LPL intensity undergoes switching between two different conditions as well, which can be visually discerned by the naked eye, enabling visual sensing of volatiles by LPL. This combination of photoluminescence and the visual LPL switching behavior of acids and bases in functional MOFs may provide an effective avenue for stimulus response, anticounterfeiting, and encryption applications.

8.
Materials (Basel) ; 16(22)2023 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-38005127

RESUMO

BiFeO3/La0.7Sr0.3MnO3 (BFO/LSMO) epitaxial heterostructures were successfully synthesized by pulsed laser deposition on (001)-oriented SrTiO3 single-crystal substrates with Au top electrodes. Stable bipolar resistive switching characteristics regulated by ferroelectric polarization reversal was observed in the Au/BFO/LSMO heterostructures. The conduction mechanism was revealed to follow the Schottky emission model, and the Schottky barriers in high-resistance and low-resistance states were estimated based on temperature-dependent current-voltage curves. Further, the observed memristive behavior was interpreted via the modulation effect on the depletion region width and the Schottky barrier height caused by ferroelectric polarization reversal, combining with the oxygen vacancies migration near the BFO/LSMO interface.

9.
Chemistry ; 29(52): e202301469, 2023 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-37385953

RESUMO

In this work, an organic-inorganic hybrid crystal, violet-crystal (VC), was used to etch the nickel foam (NF) to fabricate a self-standing electrode for the water oxidation reaction. The efficacy of VC-assisted etching manifests the promising electrochemical performance towards the oxygen evolution reaction (OER), requiring only ~356 and ~376 mV overpotentials to reach 50 and 100 mA cm-2 , respectively. The OER activity improvement is attributed to the collectively exhaustive effects arising from the incorporation of various elements in the NF, and the enhancement of active site density. Furthermore, the self-standing electrode is robust, exhibiting a stable OER activity after 4,000 cyclic voltammetry cycles, and ~50 h. The anodic transfer coefficients (αa ) show that the first electron transfer step is the rate-determining step on the surface of NF-VCs-1.0 (NF etched by 1 g of VCs) electrode, while the chemical step involving dissociation following the first electron transfer step is identified as the rate-limiting step in other electrodes. The lowest Tafel slope value observed in the NF-VCs-1.0 electrode indicates the high surface coverage of oxygen intermediates and more favorable OER reaction kinetics, as confirmed by high interfacial chemical capacitance and low charge transport/interfacial resistance. This work demonstrates the importance of VCs-assisted etching of NF to activate the OER, and the ability to predict reaction kinetics and rate-limiting step based on αa values, which will open new avenues to identify advanced electrocatalysts for the water oxidation reaction.

10.
J Nat Prod ; 86(5): 1240-1250, 2023 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-37145877

RESUMO

Mass spectrometry-based dereplication and prioritization led to the discovery of four multi-N-methylated cyclodecapeptides, auyuittuqamides E-H (1-4), from a soil-derived Sesquicillium sp. The planar structures of these compounds were elucidated based on analysis of HRESIMS and NMR data. Absolute configurations of the chiral amino acid residues were assigned by a combination of the advanced Marfey's method, chiral-phase LC-MS analysis, and J-based configuration analysis, revealing that 1-4 contain both d- and l-isomers of N-methylleucine (MeLeu). Differentiation of d- and l-MeLeu in the sequence was achieved by advanced Marfey's analysis of the diagnostic peptide fragments generated from partial hydrolysis of 1. Bioinformatic analysis identified a putative biosynthetic gene cluster (auy) for auyuittuqamides E-H, and a plausible biosynthetic pathway was proposed. These newly identified fungal cyclodecapeptides (1-4) displayed in vitro growth inhibitory activity against vancomycin-resistant Enterococcus faecium with MIC values of 8 µg/mL.


Assuntos
Aminoácidos , Fragmentos de Peptídeos , Aminoácidos/química , Cromatografia Líquida , Espectrometria de Massas , Estrutura Molecular , Peptídeos Cíclicos/análise , Peptídeos Cíclicos/química
11.
Nutrients ; 15(8)2023 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-37111171

RESUMO

This study aimed to investigate the dose-response effect of Bifidobacterium breve CCFM683 on relieving psoriasis and its underlying patterns. Specifically, the expression of keratin 16, keratin 17, and involucrin were substantially decreased by administration of 109 CFU and 1010 CFU per day. Moreover, interleukin (IL)-17 and TNF-α levels were substantially decreased by 109 and 1010 CFU/day. Furthermore, the gut microbiota in mice treated with 109 or 1010 CFU/day was rebalanced by improving the diversity, regulating microbe interactions, increasing Lachnoclostridium, and decreasing Oscillibacter. Moreover, the concentrations of colonic bile acids were positively correlated with the effectiveness of the strain in relieving psoriasis. The gavage dose should be more than 108.42 CFU/day to improve psoriasis according to the dose-effect curve. In conclusion, CCFM683 supplementation alleviated psoriasis in a dose-dependent manner by recovering microbiota, promoting bile acid production, regulating the FXR/NF-κB pathway, diminishing proinflammatory cytokines, regulating keratinocytes, and maintaining the epidermal barrier function. These results may help guide probiotic product development and clinical trials in psoriasis.


Assuntos
Bifidobacterium breve , Probióticos , Psoríase , Animais , Camundongos , Psoríase/induzido quimicamente , Psoríase/tratamento farmacológico , Queratinócitos , Citocinas
12.
Nat Chem ; 15(1): 119-128, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36280766

RESUMO

Interactions between the microbiota and their colonized environments mediate critical pathways from biogeochemical cycles to homeostasis in human health. Here we report a soil-inspired chemical system that consists of nanostructured minerals, starch granules and liquid metals. Fabricated via a bottom-up synthesis, the soil-inspired chemical system can enable chemical redistribution and modulation of microbial communities. We characterize the composite, confirming its structural similarity to the soil, with three-dimensional X-ray fluorescence and ptychographic tomography and electron microscopy imaging. We also demonstrate that post-synthetic modifications formed by laser irradiation led to chemical heterogeneities from the atomic to the macroscopic level. The soil-inspired material possesses chemical, optical and mechanical responsiveness to yield write-erase functions in electrical performance. The composite can also enhance microbial culture/biofilm growth and biofuel production in vitro. Finally, we show that the soil-inspired system enriches gut bacteria diversity, rectifies tetracycline-induced gut microbiome dysbiosis and ameliorates dextran sulfate sodium-induced rodent colitis symptoms within in vivo rodent models.


Assuntos
Colite , Microbioma Gastrointestinal , Humanos , Animais , Solo/química , Colite/induzido quimicamente , Colite/metabolismo , Homeostase , Modelos Animais de Doenças
13.
Artigo em Inglês | MEDLINE | ID: mdl-36361481

RESUMO

Paroxetine is a common pharmaceutical to treat depression and has been found to pose threats to aquatic organisms. However, little is known about the effects of paroxetine on the nutrient cycle in aquatic environments. Therefore, DNA metabarcoding is used in this study to analyze the effects of paroxetine on multi-trophic microorganisms and nitrogen transformation in river sediments. Although paroxetine has no significant effect on the diversity of microbenthos, changes in benthic nitrogen-converting bacteria are consistent with the change in the various forms of nitrogen in the sediment, indicating that paroxetine affects the nitrogen conversion process by affecting nitrogen-converting bacteria. In addition, it is found that paroxetine has the ability to influence nitrogen transformation in an indirect way by affecting the trophic transfer efficiency of higher trophic levels (meiofauna and protozoa, protozoa and protozoa), subsequently affecting the growth of nitrogen-converting bacteria through a top-down mechanism (i.e., predation).The results show that paroxetine affects nitrogen transformation directly by affecting nitrogen-converting bacteria and indirectly through top-down effects, emphasizing that the assessment of paroxetine's ecological risks should consider species within different trophic levels.


Assuntos
Cadeia Alimentar , Rios , Nitrogênio , Paroxetina/farmacologia , Organismos Aquáticos , Bactérias , Sedimentos Geológicos/microbiologia , Ecossistema
14.
Nanomaterials (Basel) ; 12(17)2022 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-36080054

RESUMO

Continued development of lithium-ion batteries is limited by the shortage of Li element. In this situation, the exploration of high-performance sodium-ion batteries is attracting much attention. In this experimental work, Na2/3Ni1/4Mn34O2 film cathode materials were fabricated by excimer laser deposition at different oxygen partial pressures. X-ray diffraction studies and field emission scanning electron microscopy revealed high c-axis orientation and uniform grain distribution, respectively, in the deposited films. Furthermore, after 30 cycles under a current density of 13 mA g-1, the film samples deposited at an oxygen partial pressure of 65 Pa exhibited a high capacity-retention of 91%. The film structure also had a large-current discharge performance, which makes practical applications possible.

15.
ACS Appl Mater Interfaces ; 14(25): 29099-29110, 2022 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-35713882

RESUMO

The frame structure combined with water- and heat-transfer capabilities fully satisfies the requirements of photothermal conversion materials in seawater evaporation applications. Meanwhile, it must integrate the characteristics of a high photothermal conversion rate, thermal management, and water transportation. Herein, lamellar porous films were successfully designed and synthesized by a simple ultrasonic-assisted vacuum filtration method. In this process, polystyrene sulfonate@carbon nanotubes/reduced graphene oxide (PSS@CNT/rGO) lamellar films were constructed by the one-dimensional synthesis of PSS@CNT self-assembled at the molecular scale and the two-dimensional matrix material rGO. It is worth noting that the lamellar film exhibits a high specific surface area (285.5 m2·g-1), which is reflected in its abundant nanopores. Among them, the porous network system composed of nanochannels can provide efficient water supply and steam-transfer ability and strengthen the heat insulation performance of thermal localization, which is beneficial to photothermal evaporation. The obtained PSS@CNT/rGO lamellar films achieved a condensed water yield of 1.825 kg·m-2·h-1 under 1 sun illumination (1 kW·m-2), and their solar-vapor conversion efficiency was 97.1%. Simultaneously, the interaction between the water flow and the carbon material interface was also used to generate additional electric energy output. The maximum open-circuit voltage of 0.46 V was generated at both termini of the PSS@CNT/rGO lamellar film, which successfully realized the multieffect utilization of energy. These results show that the multistage assembly strategy is a facile and effective means for the development of an efficient evaporation photothermal film, which offers significant value in the field of photothermal seawater evaporation and power generation.

16.
J Antibiot (Tokyo) ; 75(5): 247-257, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35288678

RESUMO

Three new lipopeptaibols, halovirs I-K (1-3), were isolated from the solid culture of the phytopathogenic fungus Paramyrothecium roridum NRRL 2183. Their planar structures, which consist of a hexapeptide backbone and acyl substitutions at the N- and C-termini, were elucidated by comprehensive analysis of the 1D and 2D NMR spectroscopic data along with the detailed interpretation of the MS/MS fragmentation pattern. Absolute configurations of the amino acid/1,2-amino alcohol residues were determined using the advanced Marfey's method. Bioinformatics analysis of the genome assembly of P. roridum NRRL 2183 revealed a gene cluster that is likely responsible for the biosynthesis of halovirs I-K. Analysis of the module and domain organization of the putative halovir synthetase PrHalA indicated that the assembly of 1-3 proceeds in an unconventional nonlinear fashion. 1 and 2 exhibited potent antibacterial activity against both antibiotic-sensitive and multidrug-resistant Gram-positive pathogens. These lipopeptaibols also displayed significant cytotoxicity toward human lung carcinoma A549, human breast carcinoma MCF-7, and human cervical carcinoma HeLa cells with IC50 values ranging from 1.3 to 3.3 µM.


Assuntos
Antineoplásicos , Carcinoma , Hypocreales , Antibacterianos/farmacologia , Antineoplásicos/química , Células HeLa , Humanos , Hypocreales/química , Estrutura Molecular , Espectrometria de Massas em Tandem
17.
IEEE Trans Cybern ; 52(4): 2440-2452, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32649285

RESUMO

Deep multitask learning (MTL) shares beneficial knowledge across participating tasks, alleviating the impacts of extreme learning conditions on their performances such as the data scarcity problem. In practice, participators stemming from different domain sources often have varied complexities and input sizes, for example, in the joint learning of computer vision tasks with RGB and grayscale images. For adapting to these differences, it is appropriate to design networks with proper representational capacities and construct neural layers with corresponding widths. Nevertheless, most of the state-of-the-art methods pay little attention to such situations, and actually fail to handle the disparities. To work with the dissimilitude of tasks' network designs, this article presents a distributed knowledge-sharing framework called tensor ring multitask learning (TRMTL), in which the relationship between knowledge sharing and original weight matrices is cut up. The framework of TRMTL is flexible, which is not only capable of sharing knowledge across heterogenous networks but also able to jointly learn tasks with varied input sizes, significantly improving performances of data-insufficient tasks. Comprehensive experiments on challenging datasets are conducted to empirically validate the effectiveness, efficiency, and flexibility of TRMTL in dealing with the disparities in MTL.


Assuntos
Aprendizado de Máquina , Redes Neurais de Computação , Aprendizagem , Pâncreas
18.
J Gastrointest Oncol ; 13(6): 2832-2844, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36636064

RESUMO

Background: Long non-coding ribonucleic acids (lncRNAs) are a class of non-coding RNAs implicated in the development of many malignancies, including gastric cancer (GC). In this study, we investigated the functions and molecular mechanisms of non-coding RNA activated by deoxyribonucleic acid damage (NORAD) in GC. Methods: NORAD expression at the messenger RNA levels was determined by quantitative reverse transcriptase (RT)-polymerase chain reaction assays. Cell proliferation, migration, and invasion were detected by Cell Counting Kit-8 assays, in-vivo tumor formation assays, and Transwell assays. Cell-cycle distribution was detected by a flow cytometry analysis. NORAD location was detected by nucleocytoplasmic fractionation assays. The interaction between NORAD and the microRNA-204-5p (miR-204-5p)/Lysine Methyltransferase 2D (KMT2D) axis was verified by dual-luciferase reporter gene assays and RNA binding protein immunoprecipitation (RIP) assays. Western blot was used to study the phosphatase and tensin homolog (PTEN)/phosphoinositide 3-kinases (PI3K)/protein kinase B (AKT) signaling pathway. Results: NORAD was upregulated in the GC tissues and cell lines. The silencing of NORAD repressed cell proliferation and the Growth 2 (G2)/Mitosis (M) cell-cycle transition in GC. NORAD also regulated KMT2D expression by targeting miR-204-5p and mediated PTEN/PI3K/AKT signaling in GC. Conclusions: We found that NORAD acts as an oncogene in GC. Our findings might provide a novel therapeutic target for GC.

19.
Nat Mater ; 20(10): 1378-1384, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34341524

RESUMO

Thermoelectric materials generate electric energy from waste heat, with conversion efficiency governed by the dimensionless figure of merit, ZT. Single-crystal tin selenide (SnSe) was discovered to exhibit a high ZT of roughly 2.2-2.6 at 913 K, but more practical and deployable polycrystal versions of the same compound suffer from much poorer overall ZT, thereby thwarting prospects for cost-effective lead-free thermoelectrics. The poor polycrystal bulk performance is attributed to traces of tin oxides covering the surface of SnSe powders, which increases thermal conductivity, reduces electrical conductivity and thereby reduces ZT. Here, we report that hole-doped SnSe polycrystalline samples with reagents carefully purified and tin oxides removed exhibit an ZT of roughly 3.1 at 783 K. Its lattice thermal conductivity is ultralow at roughly 0.07 W m-1 K-1 at 783 K, lower than the single crystals. The path to ultrahigh thermoelectric performance in polycrystalline samples is the proper removal of the deleterious thermally conductive oxides from the surface of SnSe grains. These results could open an era of high-performance practical thermoelectrics from this high-performance material.

20.
ACS Appl Mater Interfaces ; 13(34): 40705-40712, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34405984

RESUMO

Molybdenum carbides have been expected to be one of the promising catalysts for the hydrogen evolution reaction (HER) due to their similar d-band electronic structures to the Pt-group metals. However, the weaker hydrogen-adsorption ability of MoC severely hinders its applications. Guided by density functional theory calculations, we put forward a strategy to design the novel MoC-based electrocatalyst with surface reconstruction through sulfur doping. The incorporation of minor sulfur not only greatly increases the number of active sites and intrinsic activity but also optimizes the electronic structure to improve the electron transfer efficiency. As a result, the as-prepared sulfur-substituted MoC tackles the limitation of the Volmer step and exhibits superior HER performance with a small Tafel slope of 48 mV dec-1. Theoretical investigations demonstrate that the terminal sulfur plays a critical role in facilitating a close to zero hydrogen adsorption energy (ΔGH*) and a lower hydrogen release barrier.

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