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1.
Nat Commun ; 11(1): 101, 2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31900395

RESUMO

Sensitive photodetection is crucial for modern optoelectronic technology. Two-dimensional molybdenum disulfide (MoS2) with unique crystal structure, and extraordinary electrical and optical properties is a promising candidate for ultrasensitive photodetection. Previously reported methods to improve the performance of MoS2 photodetectors have focused on complex hybrid systems in which leakage paths and dark currents inevitably increase, thereby reducing the photodetectivity. Here, we report an ultrasensitive negative capacitance (NC) MoS2 phototransistor with a layer of ferroelectric hafnium zirconium oxide film in the gate dielectric stack. The prototype photodetectors demonstrate a hysteresis-free ultra-steep subthreshold slope of 17.64 mV/dec and ultrahigh photodetectivity of 4.75 × 1014 cm Hz1/2 W-1 at room temperature. The enhanced performance benefits from the combined action of the strong photogating effect induced by ferroelectric local electrostatic field and the voltage amplification based on ferroelectric NC effect. These results address the key challenges for MoS2 photodetectors and offer inspiration for the development of other optoelectronic devices.

2.
Analyst ; 144(18): 5378-5380, 2019 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-31441910

RESUMO

Nitrite, widely found in the environment and the food industry, poses a great threat to human health because of its potential toxicity, and its detection is highly important. We report that a MoN nanosheet array on carbon cloth (MoN NA/CC) behaves as an efficient catalyst for nitrite reduction in neutral solution. As a nitrite sensor, this MoN NA/CC offers a wide linear range from 1 µM to 5 mM and a low detection limit of 3 nM (S/N = 3), with a high sensitivity of 4319 µA mM-1 cm-2 and long-term stability and reproducibility.

3.
J Med Virol ; 91(8): 1553-1561, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30950067

RESUMO

Accumulating evidence indicates that persistent infection with high-risk oncogenic human papillomavirus (HPV) genotypes is the most important risk factor for cervical cancer, and that the distribution of HPV genotypes varies regionally. This study explored the prevalence and genotype distribution of HPV infection among Han, Yi, and Bai women in various regions of Dali Bai Autonomous Prefecture, Yunnan Province, China. This cross-sectional study included 2779 women (20-76 years old) who were referred for 21-HPV genotype array diagnostic from five regions of Dali Bai Autonomous Prefecture between February 2013 and May 2016. Statistical methods used included a the χ2 test, Fisher's exact test, t test, and logistic regression. Overall HPV prevalence in the study population was 7.6%. HPV-52, HPV-58, HPV-18, HPV-81, and HPV-16 were the most prevalent genotypes in the study area, and notably, the prevalence of HPV-58 was significantly higher among women in Heqing County than that in other regions. Univariate analysis showed that husband's age, region, fertility status, and parity were potential factors associated with HPV infection. Multivariate logistic regression analysis revealed that Heqing County was an independent risk factor for HPV infection among women in the Dali area, moreover, Yi women showed the highest risk for HPV infections. Overall, our finding emphasizing the urgent need for an HPV screening and prevention program in Heqing County and Yi women. We also suggest that HPV-related health education should be provided not only to women, but also to men, to reduce the risk of infection in women.

4.
Nanomaterials (Basel) ; 9(3)2019 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-30862000

RESUMO

Volatile programmable metallization cell is a promising threshold switching selector with excellent characteristics and simple structures. However, the large variation of threshold voltage is a major problem for practical application. In this work, we propose a dual-layer structure to increase selectivity and improve the threshold voltage variation. Compared to single-layer devices, this dual-layer device exhibits higher selectivity (>107) and better threshold voltage uniformity with less than 5% fluctuation during 200 DC switching. The improvement is attributed to good control on the location of the filament formation and rupture after introducing a HfO2 layer. It is deduced that a major factor consists of the difference of Ag ions mobility between SiTe and HfO2 due to the grain boundary quantity.

5.
Chemistry ; 25(8): 1914-1917, 2019 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-30523656

RESUMO

Currently, NH3 production primarily depends on the Haber-Bosch process, which operates at elevated temperatures and pressures and leads to serious CO2 emissions. Electrocatalytic N2 reduction offers an environmentally benign approach for the sustainable synthesis of NH3 under ambient conditions. This work reports the development of biomass-derived amorphous oxygen-doped carbon nanosheet (O-CN) using tannin as the precursor. As a metal-free electrocatalyst for N2 -to-NH3 conversion, such O-CN shows high catalytic performances, achieving a large NH3 yield of 20.15 µg h-1 mg-1 cat. and a high Faradic efficiency of 4.97 % at -0.6 V vs. reversible hydrogen electrode (RHE) in 0.1 m HCl at ambient conditions. Remarkably, it also exhibits high electrochemical selectivity and durability.

6.
Materials (Basel) ; 11(11)2018 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-30373122

RESUMO

Synaptic devices with bipolar analog resistive switching behavior are the building blocks for memristor-based neuromorphic computing. In this work, a fully complementary metal-oxide semiconductor (CMOS)-compatible, forming-free, and non-filamentary memristive device (Pd/Al2O3/TaOx/Ta) with bipolar analog switching behavior is reported as an artificial synapse for neuromorphic computing. Synaptic functions, including long-term potentiation/depression, paired-pulse facilitation (PPF), and spike-timing-dependent plasticity (STDP), are implemented based on this device; the switching energy is around 50 pJ per spike. Furthermore, for applications in artificial neural networks (ANN), determined target conductance states with little deviation (<1%) can be obtained with random initial states. However, the device shows non-linear conductance change characteristics, and a nearly linear conductance change behavior is obtained by optimizing the training scheme. Based on these results, the device is a promising emulator for biology synapses, which could be of great benefit to memristor-based neuromorphic computing.

7.
Adv Mater ; 30(14): e1705193, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29436065

RESUMO

Cation-based resistive switching (RS) devices, dominated by conductive filaments (CF) formation/dissolution, are widely considered for the ultrahigh density nonvolatile memory application. However, the current-retention dilemma that the CF stability deteriorates greatly with decreasing compliance current makes it hard to decrease operating current for memory application and increase driving current for selector application. By centralizing/decentralizing the CF distribution, this current-retention dilemma of cation-based RS devices is broken for the first time. Utilizing the graphene impermeability, the cation injecting path to the RS layer can be well modulated by structure-defective graphene, leading to control of the CF quantity and size. By graphene defect engineering, a low operating current (≈1 µA) memory and a high driving current (≈1 mA) selector are successfully realized in the same material system. Based on systematically materials analysis, the diameter of CF, modulated by graphene defect size, is the major factor for CF stability. Breakthrough in addressing the current-retention dilemma will instruct the future implementation of high-density 3D integration of RS memory immune to crosstalk issues.

8.
Oncotarget ; 8(15): 25552-25563, 2017 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-28424423

RESUMO

The antidepressant-like effect of trans-astaxanthin, a compound present rich in algae, was evaluated through behavioral and neurochemical methods. Results showed that trans-astaxanthin treatment significantly decreased the immobility time in force swim test and tail suspension test, but did not influence locomotor activity. Trans-astaxanthin treatment did not effectively antagonize hypothermia and ptosis induced by reserpine. However, pre-treatment with para-chlorophenylalanine abolished the anti-immobility effect of trans-astaxanthin in force swim and tail suspension test. These results suggested that the mechanism of antidepressant-like effect of trans-astaxanthin may involve the serotonergic system, but not noradrenaline system. This hypothesis was confirmed by neurochemical assays which showed that trans-astaxanthin increased serotonin levels in the hippocampus, frontal cortex, striatum and hypothalamus. Furthermore, our data suggested that trans-astaxanthin decreased indoleamine 2, 3-dioxygenase activity in the hippocampus, frontal cortex and hypothalamus. Inhibition of indoleamine 2,3-dioxygenase activity subsequently decreased the kynurenine/tryptophan ratio and increased the serotonin/tryptophan ratio in these brain regions. Taken together, these findings indicate that the antidepressant-like effect of trans-astaxanthin involves the serotonergic system.


Assuntos
Antidepressivos/farmacologia , Atividade Motora/efeitos dos fármacos , Neurônios Serotoninérgicos/efeitos dos fármacos , Neurônios Serotoninérgicos/metabolismo , Serotonina/metabolismo , Animais , Comportamento Animal , Monoaminas Biogênicas/metabolismo , Encéfalo/metabolismo , Ativação Enzimática/efeitos dos fármacos , Expressão Gênica , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Masculino , Camundongos , Monoaminoxidase/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Triptofano/metabolismo , Xantofilas/farmacologia
9.
Biomed Pharmacother ; 83: 1071-1079, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27544551

RESUMO

Cistanoside A (C. A) was one of phenylethanol glycosides isolated from Cistanche deserticola, a tonic in traditional Chinese medicine. In our previous research, we demonstrated that Cistanoside A (C. A) possess the protective activities on CCl4 induced hepatotoxicity in mice, such as increasing free radicals clearing activities, alleviating lipid-overoxidation damage, and improving respiratory chain function in mitochondria. Meanwhile, our previous research also demonstrated C.A possess protective activities on alcohol induced hepatotoxicity in mice, shown in ameliorate the hepatic function indices, lightening steatosis and inflammatory infiltration, increasing free radicals clearing activities, alleviating lipid-overoxidation damage, and alleviating energy metabolism in mitochondria. The aim of this research was to evaluate the effects of Cistanoside A (C. A) on ethanol-induced damage in primary cultured mouse hepatocytes, and probe into the mechanism related. Using fluorescent staining, flow cytometer, immunohistochemistry analysis, and Western blotting, we demonstrated that C.A could enhance the survival rate of the primary cultured hepatocytes, alleviate apoptosis and necrosis, the mechanism was involved with enhance the expression of apoptosis inhibition factor bcl-2, and inhibition the expression of immediate early genes c-fos.


Assuntos
Catecóis/farmacologia , Glicosídeos/farmacologia , Hepatócitos/patologia , Substâncias Protetoras/farmacologia , Animais , Apoptose/efeitos dos fármacos , Western Blotting , Catecóis/química , Forma do Núcleo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Etanol , Glicosídeos/química , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Camundongos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo
10.
ACS Appl Mater Interfaces ; 7(40): 22587-93, 2015 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-26393528

RESUMO

Large-area and highly crystalline monolayer molybdenum disulfide (MoS2) with a tunable grain size was synthesized in a H2 atmosphere. The influence of introduced H2 on MoS2 growth and grain size, as well as the corresponding mechanism, was tentatively explored by controlling the H2 flow rate. The as-grown monolayer MoS2 displays excellent uniformity and high crystallinity evidenced by Raman and high-resolution transmission electron microscopy. The Raman results also give an indication that the quality of the monolayer MoS2 synthesized in a H2 atmosphere is comparable to that synthesized by using seed or mechanical exfoliation. In addition, the electronic properties and dielectric inhomogeneity of MoS2 monolayers were also detected in situ via scanning microwave microscopy, with measurements on impedance and differential capacitance (dC/dV). Back-gated field-effect transistors based on highly crystalline monolayer MoS2 shows a field-effect mobility of ∼13.07 cm2 V(-1) s(-1) and an Ion/Ioff ratio of ∼1.1×10(7), indicating that the synthesis of large-area and high-quality monolayer MoS2 with H2 is a viable method for electronic and optoelectronic applications.

11.
Sheng Wu Gong Cheng Xue Bao ; 29(12): 1836-46, 2013 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-24660631

RESUMO

In order to study the effects of Ca2+ in the biosynthesis of salvianolic acid B (Sal B) induced by salicylic acid (SA) in the young seedlings of Salvia miltiorrhiza, we used confocal laser scanning microscopy and high performance liquid chromatography to measure the change of relative fluorescence intensity of Ca2+ and the contents of Sal B induced by SA before and after the application of extracellular calcium channel inhibitors (VP and LaCl3), intracellular calcium channel inhibitor (LiCl), as well as intracellular calmodulin antagonist (TFP). SA could induce the calcium burst, and the Ca2+ peak could last to 2-3 min in the guard cells of S. miltiorrhiza, which prompted the biosynthesis of Sal B after the Ca2+ burst. Both Vp or LaCl3, and LiCl or TFP could inhibit the burst of Ca2+ and the biosynthesis of Sal B. The above results demonstrated that Ca2+ from the extracellular and the intracellular calcium store regulate the biosynthesis of Sal B elicited by salicylic acid in S. miltiorrhiz young seedlings.


Assuntos
Benzofuranos/metabolismo , Cálcio/metabolismo , Ácido Salicílico/farmacologia , Salvia miltiorrhiza/metabolismo , Plântula/metabolismo , Folhas de Planta/metabolismo , Transdução de Sinais
12.
Zhongguo Zhong Yao Za Zhi ; 38(20): 3424-31, 2013 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-24490547

RESUMO

OBJECTIVE: To investigate the effect of intracellular and extracellular Ca2+ on the biosynthesis of rosmarinic acid (RA) induced by salicylic acid in young seedlings of Salvia miltiorrhiza. METHOD: Young seedlings of S. miltiorrhiza were used to select an optimal concentration of salicylic acid (SA), and then use the optimal concentration of SA to investigate the effects of extracellular Ca2+ channel inhibitors Verapamil, LaCl3, intracelluar calmodulin antagonist TFP and intracelluar Ca2+ channel inhibitors LiCl on the biosynthesis of RA and related enzymes. RESULT: SA increased the accumulation of RA and the activities of PAL and TAT, especially the SA of 2 mmol x L(-1) after 24 h. SA improved the accumulation of RA to (40.51 +/- 2.16) mg x g(-1), which was 1.97 times than that of control, and the activities of PAL, TAT were 1.42 times and 1.29 times than those of the control. However, Vp, LaCl3, TFP, LiCl inhibited the effects of SA evidently. CONCLUSION: Ca2+ plays a key role in the regulation of the induction process.


Assuntos
Cálcio/metabolismo , Cinamatos/metabolismo , Depsídeos/metabolismo , Ácido Salicílico/metabolismo , Salvia miltiorrhiza/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Salvia miltiorrhiza/genética , Salvia miltiorrhiza/crescimento & desenvolvimento , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/metabolismo
13.
Sheng Wu Gong Cheng Xue Bao ; 28(3): 320-8, 2012 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-22712390

RESUMO

Rosmarinic acid (RA), a phenolic acid, is one of the important secondary metabolites produced in Salvia miltiorrhiza. To observe the influence of salicylic acid (SA), an elicitor, on the synthesis of RA and related enzymes, we treated the cell suspension cultures of S. miltiorrhiza with SA and L-a-aminooxy-beta-phenylpropionic acid (AOPP), a competitive inhibitor of tyrosine aminotransferase (TAT). Under this condition, the activities of related enzymes, such as phenylalanine ammonia-lyase and TAT were traced and assayed; the accumulative amount of RA was measured. The results showed that the PAL activity reached the peak at 4 h, 124% higher than that of the control, and the content of RA reached its maximum ((5.914 +/- 0.296) mg/g dry weight) at 8 h, after treated by 6.25 mg/L SA on day 6 of the suspension culture. The results of treatment with 0.1 micromol/L AOPP showed that AOPP affected little on the TAT activity, while the PAL activity was significantly influenced, with 44% lower than that of the control at 6 h. Meanwhile, the reduced accumulation of RA ((4.709 +/- 0.204) mg/g dry weight) paralleled with the decrease in PAL activity. The co-treatment by 0.1 micromol/L AOPP and 6.25 mg/L SA relieved the restriction imposed by AOPP on PAL, and made the cell cultures accumulate more RA than sole treatment with AOPP, indicated that SA induced the accumulation of RA in suspension cell culture of S. miltiorrhiza, and the rate-limiting effect of PAL was stronger than TAT.


Assuntos
Técnicas de Cultura de Células/métodos , Cinamatos/metabolismo , Depsídeos/metabolismo , Células Vegetais/metabolismo , Ácido Salicílico/farmacologia , Salvia miltiorrhiza/metabolismo , Fenilalanina Amônia-Liase/metabolismo , Salvia miltiorrhiza/citologia , Salvia miltiorrhiza/crescimento & desenvolvimento , Suspensões , Tirosina Transaminase/metabolismo
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