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1.
Artigo em Inglês | MEDLINE | ID: mdl-32057228

RESUMO

Direct growth of vertically-oriented graphene (VG) nanowalls on soda-lime glass has practical significance in extending the application of graphene to daily-life related areas, such as gas sensors and conductive electrodes, via combining their complementary properties and applications. However, low temperature deposition derived VG films (e.g. on glass) usually present relative low conductivity and optical transparency. To tackle this issue, an ethanol-precursor-based, radio-frequency plasma enhanced chemical vapor deposition (rf-PECVD) route for the synthesis of VG-nanowalls is developed in this research, around the softening temperature of soda-lime glass (~600 ℃) templates. The average sheet resistance ~2.4 kΩ·sq-1 (at transmittance ~81.6%) is only one-half of that achieved by a traditional methane-precursor-based PECVD route. Based on the highly conductive and optical transparent VG/glass, as well its scalable size up to 25-inch scale, high-performance reversible thermochromic devices were successfully constructed with VG/glass as transparent heaters. Hereby, this work should propel the scalable synthesis and applications of highly conductive VG films on glass in next-generation transparent electronics and switchable windows.

2.
Small ; 16(4): e1905485, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31894647

RESUMO

Direct growth of graphene on glass can bring an innovative revolution by coupling the complementary properties of traditional glass and modern graphene (such as transparency and conductivity), offering brand new daily-life related applications. However, preparation of high-quality graphene on nonmetallic glass is still challenging. Herein, the direct route of low sheet resistance graphene on glass is reported by using in situ-introduced water as a mild etchant and methane as a carbon precursor via chemical vapor deposition. The derived graphene features with large domain sizes and few amorphous carbon impurities. Intriguingly, the sheet resistance of graphene on glass is dramatically lowered down to ≈1170 Ω sq-1 at the optical transmittance ≈93%, ≈20% of that derived without the water etchant. Based on the highly conductive and optical transparent graphene on glass, a see-through thermochromic display is thus fabricated with transparent graphene glass as a heater. This work can motivate further investigations of the direct synthesis of high-quality graphene on functional glass and its versatile applications in transparent electronic devices or displays.

3.
Cell Death Dis ; 11(1): 13, 2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31907347

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

4.
Adv Mater ; 32(4): e1905896, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31825536

RESUMO

2D magnetic materials have attracted intense attention as ideal platforms for constructing multifunctional electronic and spintronic devices. However, most of the reported 2D magnetic materials are mainly achieved by the mechanical exfoliation route. The direct synthesis of such materials is still rarely reported, especially toward thickness-controlled synthesis down to the 2D limit. Herein, the thickness-tunable synthesis of nanothick rhombohedral Cr2 S3 flakes (from ≈1.9 nm to tens of nanometers) on a chemically inert mica substrate via a facile chemical vapor deposition route is demonstrated. This is accomplished by an accurate control of the feeding rate of the Cr precursor and the growth temperature. Furthermore, it is revealed that the conduction behavior of the nanothick Cr2 S3 is variable with increasing thickness (from 2.6 to 4.8 nm and >7 nm) from p-type to ambipolar and then to n-type. Hereby, this work can shed light on the scalable synthesis, transport, and magnetic properties explorations of 2D magnetic materials.

5.
Plant Biotechnol J ; 18(2): 540-552, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31350935

RESUMO

Sugar transporters are necessary to transfer hexose from cell wall spaces into parenchyma cells to boost hexose accumulation to high concentrations in fruit. Here, we have identified an apple hexose transporter (HTs), MdHT2.2, located in the plasma membrane, which is highly expressed in mature fruit. In a yeast system, the MdHT2.2 protein exhibited high 14 C-fructose and 14 C-glucose transport activity. In transgenic tomato heterologously expressing MdHT2.2, the levels of both fructose and glucose increased significantly in mature fruit, with sugar being unloaded via the apoplastic pathway, but the level of sucrose decreased significantly. Analysis of enzyme activity and the expression of genes related to sugar metabolism and transport revealed greatly up-regulated expression of SlLIN5, a key gene encoding cell wall invertase (CWINV), as well as increased CWINV activity in tomatoes transformed with MdHT2.2. Moreover, the levels of fructose, glucose and sucrose recovered nearly to those of the wild type in the sllin5-edited mutant of the MdHT2.2-expressing lines. However, the overexpression of MdHT2.2 decreased hexose levels and increased sucrose levels in mature leaves and young fruit, suggesting that the response pathway for the apoplastic hexose signal differs among tomato tissues. The present study identifies a new HTs in apple that is able to take up fructose and glucose into cells and confirms that the apoplastic hexose levels regulated by HT controls CWINV activity to alter carbohydrate partitioning and sugar content.

6.
BMC Public Health ; 19(1): 1603, 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31791295

RESUMO

BACKGROUND: An exclusive breastfeeding rate in the first 6 months of life of at least 50% is one of the six World Health Organization global nutrition targets for 2025. However, the exclusive breastfeeding rate in China is quite low and decreasing which makes it urgent to explore effective ways to reverse the current downward trend. As mobile technologies have rapidly developed, mobile communication apps such as WeChat (one of the largest social networking platforms in China) are well accepted and have the potential to improve health behaviors in a convenient way. The current paper describes the study protocol of a WeChat intervention that aims to promote breastfeeding in rural areas in China. METHODS: The study is designed as a randomized controlled trial in rural Qinghai Province, China. Women who are 14-36 weeks pregnant will be randomized to routine antenatal and postnatal care, or routine care plus the WeChat breastfeeding education. pregnant women with a severe disease and complications of pregnancy or HIV-1 will be excluded. Breastfeeding knowledge and promotion information will be delivered to the intervention group through a WeChat official account from 3 months pregnancy to 6 months postpartum. The outcome assessments are conducted at baseline through face-to-face interviews, and at one week, 1 month, 3 months and 6 months postpartum by telephone interviews. The primary outcome is difference in the exclusive breastfeeding rate at 1 month, 3 months, and 6 months postpartum between the intervention group and the control group. Secondary outcomes include the overall duration of any and exclusive breastfeeding across the first 6 months postpartum; mothers' knowledge of breastfeeding; the proportion of early initiation of breastfeeding; and the timing of the introduction of solid food to infants. Intention-to-treat-analysis will be used. Survival analysis will be used to compare the overall duration of any and exclusive breastfeeding between groups. DISCUSSION: This study is the first effort to promote exclusive breastfeeding through WeChat in China. Our results will provide scientific evidence for the effect of health education through WeChat on breastfeeding. Thereby this may offer a comprehensive intervention to promote exclusive breastfeeding in China and other settings. TRIAL REGISTRATION: Chinese Clinical Trial Registry -ChiCTR1800017364. Registered 26 July 2018. http://www.chictr.org.cn/showproj.aspx?proj=29325.

7.
ACS Cent Sci ; 5(11): 1834-1843, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31807685

RESUMO

Urea methanolysis is a green alternative to synthesize dimethyl carbonate (UM-to-DMC). However, it is strongly challenged by the generated NH3 induced thermodynamic equilibrium limitation and the azeotropic products' separation. Herein, these predicaments are well-relieved by introducing membranes in both reaction and product separation. An NH3 permselective membrane reactor (MR) based on modified SAPO-34 membrane is successfully realized for UM-to-DMC. The permselectivity and acidity of the SAPO-34 membrane are significantly adjusted to cater the strict molecular sieving of NH3/methanol and chemical inertness upon the reaction. The MR exhibits excellent reactant conversion and DMC selectivity, resulting in >139% higher DMC yield than that of the nonmembrane reactor, due to in situ removal of NH3 by the membrane. The MR also demonstrates reliable chemical, thermal, and mechanical stability during >2000 h. Moreover, the regular SAPO-34 membrane with controlled thickness presents remarkable separation performance for the methanol-DMC azeotrope, in which the methanol-DMC separation factors and the methanol permeance are 1-2 orders of magnitude higher than those of the polymeric membranes. This study suggests the great potential that integration of such membranes offers for process intensification, energy savings, and efficiency improvement in a series of urea alcoholysis and even other NH3 releasing reactions.

8.
ACS Appl Mater Interfaces ; 11(51): 48221-48229, 2019 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-31782301

RESUMO

Vertical heterostructures formed by stacks of two-dimensional (2D) layered materials with disparate electronic properties have attracted tremendous attention for their versatile applications. The targeted fabrication of such vertical stacks with clean interfaces and a specific stacking sequence remains challenging. Herein, we design a two-step chemical vapor deposition route for the direct synthesis of unconventional graphene/PtSe2 vertical stacks (Gr/PtSe2) on conductive Au foil substrates. Monolayer PtSe2 (1L-PtSe2) was detected to preferentially grow at the interface of the predeposited Gr layer and the Au foil substrate rather than on the Gr surface. The concurrent effect from the strong interaction of PtSe2/Au and the space confinement effect of Gr/Au are proposed to be the essential mechanisms. Particularly, this unique growth system allows us to uncover the intrinsic property of 1L-PtSe2 and the interfacial coupling effect using scanning tunneling microscopy/spectroscopy. Our work should hereby enable significant advances in the synthesis of 2D-based vertical heterostructures and in the exploration of their intrinsic interface properties.

9.
Nanoscale ; 11(47): 22971-22979, 2019 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-31769772

RESUMO

As a coordination polymer built of [Mo3S13]2- clusters, amorphous nanoscale MoSx (a-MoSx) is an attractive electrocatalyst for the hydrogen evolution reaction (HER) due to its abundant active sites and scalable synthesis. However, clarifying the internal catalytic mechanism and achieving even higher HER performance with scalable size are still challenging. Herein, a new hybrid catalyst of a-MoSx flakes decorated with Ni3S2 nanocrystals (size < 10 nm) has been successfully synthesized on 10 × 20 cm2-sized Ni foam by a portable hydrothermal route. As the strong interaction of [Mo3S13]2- clusters with Ni3S2 is evidenced by comprehensive binding state and Raman characterization, the polymerization effect of [Mo3S13]2- itself and the perfect interfaces between [Mo3S13]2- clusters and Ni3S2 are also confirmed by density functional theory calculations. These two factors greatly lower the absorption energy of hydrogen nearly to zero, leading to much improved HER activity. Current densities of 100 and 600 mA cm-2 are achieved at overpotentials of 181 and 246 mV, respectively, which are so far the highest values approaching practical applications. The findings of this work provide a fundamental reference about the catalytic origin of a-MoSx based catalysts, and shed light on the practical applications of non-precious electrocatalysts for their compatibility with low cost batch production.

10.
Anal Bioanal Chem ; 411(30): 8073-8080, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31761955

RESUMO

Vitamin A deficiency (VAD) is a major micronutrient deficiency in children. Although plasma and serum retinol levels are proposed as the key indicators of VAD, collecting and transporting plasma and serum are difficult and inconvenient in field studies. Dried blood spot (DBS) retinol has been used as an alternative to plasma retinol in several epidemiological and clinical studies. A limitation of methods that use DBS retinol is the instability and apparent loss of retinol in DBSs. Therefore, an accurate, reliable method for stabilizing retinol in DBSs and quantifying and comparing DBS retinol concentrations with equivalent plasma retinol levels is required. In this study, antioxidants on paper combined with vacuum treatment were found to greatly increase the stability of DBS retinol during 120 min of air drying and 30 days of room-temperature storage. A surrogate matrix of whole blood prepared using a mixture of human erythrocytes and 2% BSA in PBS was firstly used in DBS retinol determination based on the fact that retinol is excluded from erythrocytes. The method was linear in the concentration range of 0.04-300 µg/mL. Both the between-run (n = 5) and within-run (n = 6) precision (relative standard deviations, RSD%) were below 8.42%. The spiked recoveries at 3 concentrations ranged from 86.48 to 98.13%. The internal standard (IS)-normalized matrix factor (MF) was 99.72% with a RSD% of 10.50% (n = 3). The accuracy was calibrated using two National Institute of Standards and Technology (NIST) serum-generated calibrants at concentrations of 0.1962 and 0.3948 g/mL, and relative errors (RE% values) of 0.07% and 4.95% were found, respectively. A simple calibration model was first developed to convert DBS retinol concentration to the equivalent plasma retinol concentration, thereby enabling comparisons with clinical reference ranges and with studies using serum or plasma samples. Graphical abstract.


Assuntos
Cromatografia Líquida/métodos , Teste em Amostras de Sangue Seco , Espectrometria de Massas em Tandem/métodos , Vitamina A/sangue , Calibragem , Humanos , Reprodutibilidade dos Testes
11.
Iran J Public Health ; 48(9): 1617-1626, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31700817

RESUMO

Background: We aimed to establish a reference standard of Body Mass Index (BMI) for the growth of preschool children in China. Methods: We monitored and obtained the height and weight of 50702 children aged 3-6 yr in 31 provinces in mainland China in 2014. The reference standard and percentile curve of BMI preschool children aged 3-6 yr old were formulated by using Lambda-Median-Sigma (LMS) method in China. Results: The common grounds of the male and female children were as follows: the percentile maps were similar in shape; the graphs of children aged 4-6 were approximately horn shaped. The differences between male and female children were as follows: the BMI values of male children in the same age group and the same percentile were higher than those of the female children. The change pattern of male children was larger than that of female children. BMI of 3 yr old and 6 yr old children was larger than those of 4 yr old and 5 yr old. During the change from low percentile to high percentile, the BMI values of Chinese male children exceeded WHO to a larger extent, and the BMI values of Chinese female children were substantially consistent with WHO, but the high percentile greater than P95 exceeded WHO. Conclusion: The BMI growth chart developed can be applied in monitoring the growth and nutrition of preschool children in China. We recommend the promotion of the results in the field of preventive health care.

13.
J Exp Clin Cancer Res ; 38(1): 429, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31660998

RESUMO

BACKGROUND: miR-133a-3p has been recently discovered to be down-regulated in various human malignancies, including breast cancer, and reduced miR-133a-3p levels have been significantly associated with breast cancer cell growth and invasion. However, the regulatory mechanisms leading to abnormal expression of miR-133a-3p in breast cancer remain obscure. METHODS: qRT-PCR was applied to detect the expression of miR-133a-3p in breast cancer tissues and cell lines. Bisulfite sequencing was used to detect the degree of methylation of the miR-133a-3p promoter. The effects of miR-133a-3p on breast cancer in vitro were examined by cell proliferation assay, transwell assay, flow cytometry, and western blotting. Bioinformatic analysis, dual-luciferase assay and RIP assay were employed to identify the interaction between miR-133a-3p and MAML1. A xenograft model was used to show the metastasis of breast cancer cells. RESULTS: We confirmed that miR-133a-3p was silenced by DNA hypermethylation in breast cancer cell lines and tissues, which predicted poor prognosis in breast cancer patients, and reducing miR-133a-3p expression led to a significant increase in the migration, invasion, proliferation, and stemness of breast cancer cells in vitro. Mastermind-like transcriptional coactivator 1 (MAML1) was confirmed to be a target of miR-133a-3p involved in regulating breast cancer metastasis both in vitro and in vivo. Moreover, a series of investigations indicated that MAML1 initiated a positive feedback loop, which could up-regulate DNA methyltransferase 3A (DNMT3A) to promote hypermethylation of the miR-133a-3p promoter. CONCLUSION: Taken together, our findings revealed a novel miR-133a-3p/MAML1/DNMT3A positive feedback loop in breast cancer cells, which may become a potential therapeutic target for breast cancer.

14.
Medicine (Baltimore) ; 98(41): e17493, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31593114

RESUMO

The aim of this study was to assess the bedside brain function monitoring of color density spectral array (CDSA) for early prognostic evaluation of coma patients in pediatric intensive care unit (PICU).Forty-two consecutive pediatric coma patients were enrolled. The individual conscious state was evaluated according to the Glasgow coma scale (GCS). CDSA parameters including CDSA pattern (CDSAP), sleep-wake cycle (SWC), sleep stage (SS), and drug-induced fast wave activity (DIFWA) were recorded. Three months later, prognosis was evaluated according to pediatric cerebral performance category (PCPC) score, based on which the patients were divided into FP-group (favorable prognosis) and PP-group (poor prognosis).The changeable type of CDSAP, appearance of SWC, SS, and DIFWA were significantly correlated with favorable prognosis. Both GCS and SWC were significantly correlated with the prognosis. However, there was substantial overlap in GCS between FP-group and PP-group. Although the absence of SWC was statistically an independent risk factor for poor prognosis but with a high false positive rate (0.143), a linear logistic regression showed the odds ratio of GCS for predicting prognosis was 0.93 (95% confidence interval: 0.48-1.80; P = .83) and that of SWC was 0.12 (95% confidence interval: 0.03-0.47; P = .03). Furthermore, the absence of SWC was correlated with poor prognosis in nonintracranial infection patients.Our study found that several CDSA factors are associated with prognosis of coma patients in PICU. SWC may be a potential indicator for evaluating the prognosis of coma patients in PICU.


Assuntos
Coma/diagnóstico , Monitores de Consciência/estatística & dados numéricos , Unidades de Terapia Intensiva Pediátrica/estatística & dados numéricos , Testes Imediatos , Adolescente , Criança , Pré-Escolar , Colorimetria/métodos , Colorimetria/estatística & dados numéricos , Feminino , Escala de Coma de Glasgow , Humanos , Lactente , Modelos Logísticos , Masculino , Valor Preditivo dos Testes , Prognóstico
15.
J Am Chem Soc ; 141(47): 18694-18703, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31558019

RESUMO

Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs) have attracted tremendous interest due to their intriguing physical properties and broad application potential. However, batch production of high-quality 2D MTMDCs based on existing synthesis on 2D surfaces remains a huge challenge. Herein, a universal synthetic route for the scalable synthesis of high-quality 2D MTMDC (e.g., TaS2, V5S8, and NbS2) nanosheets using microcrystalline NaCl crystals as templates via a facile chemical vapor deposition method is reported. Obviously, this synthetic route is perfectly compatible with a facile water dissolution-filtration process for obtaining high-purity MTMDC nanosheet powders. Representatively, a thickness-uniform 1T-TaS2 nanosheet product can be achieved that shows unexceptionable dispersibility in ethanol, which allows its assembly onto arbitrary substrates/electrodes for high-performance energy-related applications, herein serving as a high-performance electrocatalyst for the hydrogen evolution reaction. This work sheds light on the batch production, green transfer, and energy-related application of 2D MTMDC materials.

16.
Small ; 15(45): e1902789, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31544354

RESUMO

Palladium diselenide (PdSe2 ) is an emerging 2D layered material with anisotropic optical/electrical properties, extra-high carrier mobility, excellent air stability, etc. So far, ultrathin PdSe2 is mainly achieved via mechanical exfoliation from its bulk counterpart, and the direct synthesis is still challenging. Herein, the synthesis of ultrathin 2D PdSe2 on conductive Au foil substrates via a facile chemical vapor deposition route is reported. Intriguingly, an anisotropic growth behavior is detected from the evolution of ribboned flakes with large length/width ratios, which is well explained from the orthorhombic symmetry of PdSe2 . A unique even-layered growth mode from 2 to 20 layers is also confirmed by the perfect combination of onsite scanning tunneling microscopy characterizations, through deliberately scratching the flake edge to expose both even and odd layers. This even-layered, ribboned 2D material is expected to serve as a perfect platform for exploring unique physical properties, and for developing high-performance electronic and optoelectronic devices.

17.
Nat Commun ; 10(1): 4263, 2019 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-31537790

RESUMO

Mesostriatal dopaminergic neurons possess extensively branched axonal arbours. Whether action potentials are converted to dopamine output in the striatum will be influenced dynamically and critically by axonal properties and mechanisms that are poorly understood. Here, we address the roles for mechanisms governing release probability and axonal activity in determining short-term plasticity of dopamine release, using fast-scan cyclic voltammetry in the ex vivo mouse striatum. We show that brief short-term facilitation and longer short term depression are only weakly dependent on the level of initial release, i.e. are release insensitive. Rather, short-term plasticity is strongly determined by mechanisms which govern axonal activation, including K+-gated excitability and the dopamine transporter, particularly in the dorsal striatum. We identify the dopamine transporter as a master regulator of dopamine short-term plasticity, governing the balance between release-dependent and independent mechanisms that also show region-specific gating.


Assuntos
Axônios/metabolismo , Corpo Estriado/metabolismo , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Dopamina/metabolismo , Neurônios Dopaminérgicos/metabolismo , Animais , Transporte Biológico , Inibidores da Captação de Dopamina/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Plasticidade Neuronal/fisiologia
18.
Org Lett ; 21(20): 8285-8289, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31553197

RESUMO

A series of chalcogen-containing carborane derivatives were synthesized through a one-pot reaction. The nonconjugated six-membered ring of carborane-fused disulfide (1) can be electrochemically reduced to a dithiolate derivative. The five-membered ring of carborane-fused chalcogenophenes (2-4) showed aromaticity and considerable σ-π conjugation. The dicarborane chalcogenides (5-7) showed intramolecular charge-transfer-induced emission. These chalcogen-containing carborane derivatives provided a useful platform to study the electron interaction systematically and shed some light on the design of carborane-based optoelectronic materials.

19.
Ecotoxicol Environ Saf ; 184: 109627, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31509782

RESUMO

The toxicities of heavy metals in sediments are related to their bioavailability, which is critical for deriving reliable sediment quality guidelines. To evaluate the bioavailability of the metals (Cd, Cu, Ni, Pb and Zn), sediments were collected from Taihu Lake, one of the largest and most important freshwater lakes in China. Concentrations of simultaneously extracted metals (1-M HCl extraction, CSEM) in the sediments, metals released from sediment to pore waters and accumulated by diffusive gradients in thin films (DGT, CDGT), and dissolved metals in the overlying water (COLW) were measured separately. Sediment toxicity was assessed with tubificids (Monopylephorus limosus) and chironomids (Chironomus kiiensis and Chironomus tentans). Significant relationships existed between the total metal concentrations and CSEM, CDGT, and COLW measurements (r2 = 0.43-0.95, n = 27, p < 0.001), with stronger relationships with CSEM (r2 = 0.91-0.95) than CDGT (r2 = 0.56-0.85) and COLW (r2 = 0.43-0.71). Risk quotients were derived by dividing CSEM by sediment quality guideline values (SQGVs), and by dividing both CDGT and COLW by water quality criteria (WQC). Toxicity of the sediments to the three species was better explained by the CSEM-based risk quotient than those derived from CDGT and COLW. The study indicated that DGT piston probes deployed face down in sediments did not accumulate metals in proportion to the bioavailable metal fraction that caused toxicity to these freshwater benthic organisms, and that single measurements of metals in overlying waters are not adequate for predicting risks of toxicity from sediments. The measurement of CSEM was determined to be effective for assessing the risk posed by the metals in the Taihu Lake sediments, but offered limited improvement over measurement of total metal concentrations.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Lagos/química , Metais Pesados/farmacocinética , Poluentes Químicos da Água/farmacocinética , Animais , Organismos Aquáticos/efeitos dos fármacos , Organismos Aquáticos/metabolismo , Disponibilidade Biológica , China , Metais Pesados/análise , Metais Pesados/toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
20.
Materials (Basel) ; 12(18)2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31509983

RESUMO

The loading and the failure mode of metal hexagon bolt joints and metal counter-sunk bolt joints of C/C composites were investigated. The joints were tested for out-of-plane loading at two temperatures (600 °C and 800 °C). The failure morphology of a lap plate was investigated, and the main failure modes were determined. The typical load-displacement curve was characterized and the test was simulated using ABAQUS non-linear finite element software. Furthermore, progressive damage was induced, and comparison of the finite element simulation with the experimental data revealed that the failures mainly occurred in the lower lap plate and were dominated by cracking and delamination of the matrix, accompanied by the pull-out of a small number of piercing fibers. Finally, the influences of the temperature, nut radius, and fixture geometry on the critical load were determined via simulation.

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