Keywords: molybdenum disulfides, growth mechanism, chemical vapor deposition, transmission electron microscopy Understanding the microscopic mechanism of chemical vapor deposition (CVD) growth of two-dimensional molybdenum disulfide (2D MoS2) is a fundamental issue towards the function-oriented controlled growth. In this work, we report results on revealing the growth kinetics of 2D MoS2 via capturing the nucleation seed, evolution morphology, edge structure and terminations at the atomic scale during CVD growth using the transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) studies. The direct growth of few-and mono-layer MoS2 onto graphene based TEM grids allow us to perform the subsequent TEM characterization without any solution-based transfer. Two forms of seeding centers are observed during 2 characterizations: (i) Mo-oxysulfide (MoOxS2-y) nanoparticles either in multi-shelled fullerene-like structures or in compact nanocrystals for the growth of fewer-layer MoS2;(ii) Mo-S atomic clusters in case of monolayer MoS2. In particular, for the monolayer case, at the early stage growth, the morphology appears in irregular polygon shape comprised with two primary edge terminations: S-Mo Klein edge and Mo zigzag edge, approximately in equal numbers, while as the growth proceeds, the morphology further evolves into near-triangle shape in which Mo zigzag edge predominates. Results from density-functional theory calculations are also consistent with the inferred growth kinetics, and thus supportive to the growth mechanism we proposed. In general, the growth mechanisms found here should also be applicable in other 2D materials, such as MoSe2, WS2 and WSe2 etc.
Mannose receptor is a member of the C-type lectin receptor family involved in pathogen molecular-pattern recognition, and plays a critical role in shaping host immune response. Single nucleotide polymorphisms (SNPs) in the MRC1 gene may affect expression levels and differences in the structure and function of proteins in different individuals, thereby affecting individual susceptibility to pulmonary tuberculosis. However, to date, MRC1 polymorphisms associated with susceptibility to pulmonary tuberculosis have not yet been reported. The present study aimed to investigate potential associations of SNPs in the MRC1 gene with pulmonary tuberculosis in a Chinese population. Six SNPs (G1186A, G1195A, T1212C, C1221G, C1303T and C1323T) in exon 7 of the MRC1 gene were genotyped using the PCR and DNA sequencing methods in the pulmonary tuberculosis patients and the healthy controls. Linkage disequilibrium analysis was performed between polymorphic sites. The study found that the allele frequency of G1186A (rs34039386) of the MRC1 gene in a Chinese population was higher in the pulmonary tuberculosis group than the healthy control group. There was a significant difference in frequency distribution between the two groups (P = 0.037; OR = 0.76; 95% CI, 0.58-0.98). Genotypic analysis also indicated that the AG genotypes in a Chinese population were significantly correlated with pulmonary tuberculosis (P < 0.01; OR = 0.57; 95% CI, 0.37-0.87). After adjustment for age and gender, G1186A sites were found to be dominant (P < 0.01; OR = 0.59; 95% CI, 0.40-0.87), over-dominant (P = 0.045; OR = 0.69; 95% CI, 0.47-0.99) and additive models (P = 0.041; OR = 0.76; 95% CI, 0.59-0.99) in association with pulmonary tuberculosis. But, no association was found between the other 5 SNPs (G1195A, T1212C, C1221G, C1303T and C1323T) and tuberculosis (P > 0.05). This study is the first to report that genetic variants in the MRC1 gene can be associated with pulmonary tuberculosis in a Chinese population, and may reduce the risk of infecting pulmonary tuberculosis. This also provides a new experimental basis to clarify the pathogenesis of pulmonary tuberculosis.
Abstract:A new control method is proposed for tension regulation in a web transport system. It is based on a unique active disturbance rejection control (ADRC) strategy, which actively compensates for dynamic changes in the system, and unpredictable external disturbances. A simulation of an industrial application is used to provide realism.The results show the effectiveness of the proposed tension controller in coping with large dynamic variations commonly seen in web tension applications.The remarkable disturbance rejection capability of an ADRC is also demonstrated.
BackgroundThe present study aimed to investigate the genetic polymorphisms in exon 4 of the NOD2 gene in tuberculosis patients and healthy controls, in order to clarify whether polymorphisms in the NOD2 gene is associated with tuberculosis.MethodsA case-control study was performed on the Chinese Han, Uygur and Kazak populations. Exon 4 of the NOD2 gene was sequenced in 425 TB patients and 380 healthy controls to identify SNPs.ResultsThe frequency of T/G genotypes for the Arg587Arg (CGT → CGG) single nucleotide polymorphism (SNP) in NOD2 was found to be significantly higher in the Uygur (34.9%) and Kazak (37.1%) populations than the Han population (18.6%). Also, the frequency of G/G genotypes for the Arg587Arg SNP was significantly higher in the Uyghur (8.3%) and Kazak (5.4%) populations than the Han population (0.9%). Meanwhile, no significant difference was found in the Arg587Arg polymorphism between the tuberculosis patients and healthy controls in the Uyghur and Kazak populations (P > 0.05) whereas, a significant difference was observed in the Arg587Arg polymorphism between the tuberculosis patients and healthy controls in the Han population (P < 0.01). The odd ratio of 2.16 (95% CI = 1.31-3.58; P < 0.01) indicated that the Arg587Arg SNP in NOD2 may be associated with susceptibility to tuberculosis in the Chinese Han population.ConclusionsOur study is the first to demonstrate that the Arg587Arg SNP in NOD2 is a new possible risk factor for tuberculosis in the Chinese Han population, but not in the Uyghur and Kazak populations. Our results may reflect racial differences in genetic susceptibility to tuberculosis.
PurposeTo investigate the association between ocular sensory dominance and interocular refractive error difference (IRED).MethodsA total of 219 subjects were recruited. The refractive errors were determined by objective refraction with a fixation target located 6 meters away. 176 subjects were myopic, with 83 being anisometropic (IRED ≥ 0.75 D). 43 subjects were hyperopic, with 22 being anisometropic. Sensory dominance was measured with a continuous flashing technique with the tested eye viewing a Gabor increasing in contrast and the fellow eye viewing a Mondrian noise decreasing in contrast. The log ratio of Mondrian to Gabor’s contrasts was recorded when a subject just detected the tilting direction of the Gabor during each trial. T-test was used to compare the 50 values collected from each eye, and the t-value was used as a subject’s ocular dominance index (ODI) to quantify the degree of ocular dominance. A subject with ODI ≥ 2 (p < 0.05) had clear dominance and the eye with larger mean ratio was the dominant one. Otherwise, a subject had an unclear dominance.ResultsThe anisometropic subjects had stronger ocular dominance in comparison to non-anisometropic subjects (rank-sum test, p < 0.01 for both myopic and hyperopic subjects). In anisometropic subjects with clear dominance, the amplitude of the anisometropia was correlated with ODI values (R = 0.42, p < 0.01 in myopic anisometropic subjects; R = 0.62, p < 0.01 in hyperopic anisometropic subjects). Moreover, the dominant eyes were more myopic in myopic anisometropic subjects (sign-test, p < 0.05) and less hyperopic in hyperopic anisometropic subjects (sign-test, p < 0.05).ConclusionThe degree of ocular sensory dominance is associated with interocular refractive error difference.
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