Structural, magnetic, and electronic properties of EuSi2 thin films on the Si(111) surface.

Searching for magnetic silicide thin films has long been a hot topic in condensed matter physics and materials science based on their fundamental physics and promising device applications. Here we report a systematic study on the structural, magnetic, and electronic properties of EuSi2 thin films on the Si(111) surface by ab initio calculations. Total energy calculations show that the EuSi2 thin film in AA stacking is more favorable than that in AB or ABC stacking. The Eu2 + ions are coupled ferromagnetically within each layer and antiferromagnetically across the adjacent silicene layers with a large local spin moment of 6.96-7.00µB derived from the Eu-4f orbital electrons. Electronic band structure calculations indicate that the monolayer EuSi2 thin film is a semiconductor with an indirect surface band gap of 0.45 eV, while the multilayer EuSi2 thin films exhibit metallic behavior. These findings provide a systematic understanding of rare-earth metal silicides on the Si surface and will provide guidance for Si-based nanoelectronics and spintronics.

La induced Si3 trimer bilayer on the Si(111) surface.

Using first-principles calculations, we identify a robust R30° reconstruction of a Si3 trimer bilayer on the Si(111) surface with a La coverage of 2/3 monolayer. Each surface unit cell contains two Si3 trimers and two La atoms, where the upper Si3 trimer is located just above the lower one with a rotation of about 60°, while two La atoms with different heights are distributed between the Si3 trimers and located on the T4 top site of the Si(111) surface, forming a honeycomb-like network structure. We find that the two La atoms have different valence states, La2+ and La3+, respectively. The high structural stability is attributed to the lower La atom saturating all the three dangling bonds of the upper Si3 trimer, while the higher La atom compensates two electrons to the lower Si3 trimer. The electronic band structure and band-decomposed charge density distribution show a semiconducting characteristic with a small surface band gap of 42 meV. Moreover, simulated STM images show a good structural match with the recent experimental observations.

Structural stability and electronic properties of alkaline-earth metal induced Si(111)-(3 × 2) surfaces.

Alkaline-earth metal (Ca, Sr, and Ba) induced Si(111)-(3 × 2) honeycomb chain-channel (HCC) surfaces have been systematically studied by means of ab initio calculations. The large adsorption energy and anisotropic diffusion energy barriers ensure the high structural stability of the one-dimensional HCC structure. Electronic band structures and band-decomposed charge density distributions reveal that the first conduction band and the third valence band level are contributed by the surface Si and metal atoms, while the top first and second valence bands are caused by the bulk silicon atoms. These results identify a larger surface band gap of 1.65-1.68 eV and provide an excellent explanation for the recent experimental observations of a band gap of 1.7 eV for the Sr/Si(111)-(3 × 2) HCC surface.

A Case-control Study of Environmental Risk Factors for Nonsyndromic Cleft of the Lip and/or Palate in Xuzhou, China.

In this study, we sought to determine the association between environmental factors and nonsyndromic cleft of the lip and/or palate (NSCLP) to understand the etiology of the disease. A total of 200 NSCLP cases and 327 controls were recruited at the Maternal and Child Health Hospital of Xuzhou City. We conducted face-to-face interviews with the mothers of both cases and controls. The factors increasing the risk of NSCLP were a positive family history [odds ratio (OR)=56.74], pesticide exposure (OR=8.90), and indoor decoration pollution (OR=4.32). On the other hand, the factors decreasing the risk of NSCLP were a high education level (OR=0.22) and supplementation of folic acid (OR=0.23) and multivitamins (OR=0.16). Positive family history, pesticide exposure, and indoor decoration pollution are associated with the risk of NSCLP. In contrast, high education level and folic acid and multivitamin supplementation are protective factors against NSCLP.

Identification of susceptibility genes in non-syndromic cleft lip with or without cleft palate using whole-exome sequencing.

BACKGROUND: Non-syndromic cleft lip with or without cleft palate (NSCL/P) is among the most common congenital malformations. The etiology of NSCL/P remains poorly characterized owing to its complex genetic heterogeneity. The objective of this study was to identify genetic variants that increase susceptibility to NSCL/P. MATERIAL AND METHODS: Whole-exome sequencing (WES) was performed in 8 fetuses with NSCL/P in China. Bioinformatics analysis was performed using commercially available software. Variants detected by WES were validated by Sanger sequencing. RESULTS: By filtering out synonymous variants in exons, we identified average 8575 nonsynonymous single nucleotide variants (SNVs). We subsequently compared the SNVs against public databases including NCBI dbSNP build 135 and 1000 Genomes Project and obtained an average of 203 SNVs. Total 12 reported candidate genes were verified by Sanger sequencing. Sanger sequencing also confirmed 16 novel SNVs shared by two or more samples. CONCLUSIONS: We have found and confirmed 16 susceptibility genes responsible for NSCL/P, which may play important role in the etiology of NSCL/P. The susceptibility genes identified in this study will not only be useful in revealing the etiology of NSCL/P but also in diagnosis and treatment of the patients with NSCL/P.

Mn-Doped Sr/Si(111)-(3 × 2) HCC Surfaces: Antiferromagnetic Semiconductors for Spintronic Applications.

Manganese and manganese silicide as promising candidates for spintronic applications have attracted great interest in recent years. Here, we adopt Sr-induced Si(111)-(3 × 2) honeycomb-chain channel (HCC) surface as a template and perform a systematical study on the structural stability and magnetic and electronic properties of Mn-doped Sr/Si(111)-(3 × 2) HCC surfaces by ab initio calculations. Our energetic and kinetic results show two robust inserting structures M6 and H4, where Mn atoms are located below the honeycomb Si chain and on the top or hollow site of the Si(111) surface. Their high structural stabilities are attributed to the doped Mn atoms that saturate all the dangling bonds of Si(111) surface. In these two structures, Mn atoms prefer antiferromagnetic coupling with the same local magnetic moment of 3 µB. Electronic band structures and band-decomposed charge density distributions reveal that these two stable surface structures have a semiconducting characteristic with a surface band gap of 0.21-0.28 eV. This work provides an antiferromagnetic system for the possible application in spintronics.

Effects of age on the peak ratio of ophthalmic artery Doppler.

ABSTRACT: This study aimed to investigate the effects of age on the peak ratio (PR) of ophthalmic artery (OA) Doppler.The initial peak velocity (P1), second peak velocity (P2) and PR of OA were detected by color Doppler ultrasonography in 147 healthy subjects. All of the subjects were divided into 6 groups (G1-G6) according to the age. (G1, 20-29 years; G2, 30-39 years; G3, 40-49 years; G4, 50-59 years; G5, 60-69 years; and G6, 70 years or older). The blood pressure and heart rate were also examined before ultrasonography. The influences of age, blood pressure and heart rate on the P1, P2, and PR were further evaluated.There were significant differences in the P2 and PR among different age groups except for P1. There were no significant differences in the P2 and PR between the first 2 groups, neither among the latter 4 groups. Nevertheless, P2 and PR in the first 2 groups were significantly different from those in the latter 4 groups. In addition, both P2 and PR (not P1) increased significantly with age, systolic and diastolic blood pressure. P1, P2 and PR were not related to heart rate. Both P2 and PR were closely related to the age. PR also had a weak relationship with systolic blood pressure.Both P2 and PR of OA Doppler increase with age. Concern should be raised when P2 and PR are used to evaluate the hemodynamic change of OA.

[Study on fingerprints of Citrus aurantium from different places by capillary electrophoresis].

OBJECTIVE: To develop a high performance capillary electrophoresis method for Citrus aurantium fingerprints to control its quality. METHOD: The background electrolyte (BGE) was an 80 mmol x L(-1) boric acid solution containing 15 mmol x L(-1) borate. The pH of the BGE was adjusted to 9.70 with KOH solution. The detection wavelength was 201 nm and a voltage of 16 kV was applied. The sample hydrodynamic injection was 0.4 ps with a duration time of 8 sec. C. aurantium was extracted by water and a set of capillary electrophoresis fingerprints (CEFP) containing 12 co-possessing peaks was obtained. RESULT: There were good similarities between the standard CEFP and each set of CEFP of C. aurantium collected from eleven different places, and their similarity coefficients were between 0.973 and 0.996. CONCLUSION: The CEFP has acceptable precision, reproducibility and stability and can be used for the quality control of C. aurantium.

Establishment of a Rabbit Model of Chronic Obstructive Sleep Apnea and Application in Cardiovascular Consequences.

BACKGROUND: Although obstructive sleep apnea (OSA) has been recognized as a major risk factor for cardiovascular complications and its clinical features are well characterized, it is difficult to replicate the OSA hypoxic model in humans. We aimed to establish an experimental rabbit model for chronic OSA and to explore its application to measure blood pressure (BP), myocardial systolic function, and oxidative stress. METHODS: The rabbit model for OSA was established by repeatedly closing the airway and then reopening it. A tube specially designed with a bag that could be alternately inflated and deflated according to a predetermined time schedule, resulting in recurrent airway occlusions and chronic intermittent hypoxia (CIH) imitating OSA patterns in humans, was used. Twenty-four rabbits were randomly divided into obstruction, sham, and control groups, and their upper airways were alternately closed for 15 s and then reopened for 105 s in a 120-s-long cycle, for 8 h each day over 12 consecutive weeks. Before and after the experiment, the BP of each rabbit was monitored. Levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in the serum, superoxide dismutase (SOD) activity, malondialdehyde (MDA) and reactive oxygen species (ROS) contents, as well as Na+-K+-ATPase/Ca2+-ATPase activities in cardiac muscle were examined. In addition, cardiac functional parameters were measured using echocardiography. RESULTS: After 3 months, all rabbits in the obstruction group manifested sleepiness performance similar to that observed in OSA patients. Traces of airflow and SpO2showed that this model mimicked the respiratory events involved in OSA, including increased respiratory effort and decreased oxygen saturation. Gradually, the BP rose each month. CIH led to obvious oxidative stress and injured myocardial systolic performance. The serum levels of IL-6 and TNF-α increased significantly (64.75 ± 9.05 pg/ml vs. 147.00 ± 19.24 pg/ml and 59.38 ± 8.21 pg/ml vs. 264.75 ± 25.54 pg/ml, respectively, both P < 0.001). Compared with the sham and the control groups, myocardial activities of Na+-K+-ATPase/Ca2+-ATPase and SOD in the obstruction group decreased markedly, while ROS and MDA content increased. CONCLUSIONS: These results show that the rabbit model for OSA simulates the pathophysiological characteristics of OSA in humans, which implies that this animal model is feasible and useful to study the mechanisms involved in the cardiovascular consequences of OSA.

Anti-tumor activity of tanshinone IIA in combined with cyclophosphamide against Lewis mice with lung cancer.

OBJECTIVE: To explore the anti-tumor activity of tanshinone IIA in combined with cyclophosphamide against Lewis mice with lung cancer and the effect on cellular immune function. METHODS: Lewis tumor cells were inoculated subcutaneously into the right armpit of mice in each group (n = 20) to establish Lewis lung cancer mice model. After model establishment, mice in the model group were given normal saline by lavage, qd. Mice in treatment I group were given intraperitoneal injection of Tan IIA, 15 mg/kg, qd. Mice in treatment II group were given intraperitoneal injection of CTX, 25 mg/kg, qd. Mice in treatment III group were given intraperitoneal injections of Tan IIA and CTX, in which the administration method of Tan IIA was the same as in treatment I group, continuously for 2 weeks, and the dosage of CTX was the same as in treatment II group, 24 h after model establishment, every other day. Mice were sacrificed 2 weeks after establishment. The tumor tissues were collected to calculate the anti-tumor rate. Immunohistochemistry was used to detect the expressions of Bcl-2, Bax, VEGF, Angiostatin, and Endostatin. FCM was used to detect T lymphocyte subsets in spleen and liver of mice. RESULTS: The tumor weight in treatment I, II, and III groups was significantly lower than that in the model group (P < 0.05). The tumor weight in treatment III group was significantly lower than that in treatment I and II groups (P < 0.05). The anti-tumor rate in treatment II and III groups was significantly higher than that in treatment I group (P < 0.05). Bcl-2 expression in the tumor tissues of treatment I, II, and III groups was significantly lower than that in the model group (P < 0.05), while Bax expression was significantly higher than that in the model group (P < 0.05). Bcl-2 expression in the tumor tissues of treatment I and II groups was significantly higher than that in treatment III group (P < 0.05), while Bax expression was significantly lower than that in treatment III group (P < 0.05). CD4+ and CD4+/CD8+ in treatment I, II, and III groups were significantly higher than those in the model group (P < 0.05). CD4+ in treatment III group was significantly higher than that in treatment I and II groups (P < 0.05), while CD4+/CD8+ was significantly higher than that in treatment II group (P < 0.05). The comparison of CD8+ among each group was not statistically significant (P > 0.05). NK cell activity in treatment I, II, and III groups was significantly higher than that in the model group (P < 0.05). NK cell activity in treatment III group was significantly higher than that in treatment I and II groups (P < 0.05). CONCLUSIONS: Tan IIA in combined with CTX can down regulate Bcl-2 expression in lung cancer tissues, up regulate Bax expression, inhibit the neovascularization of tumor tissues, and enhance the immunological function, with a significant anti-tumor activity.

Antagonism effects of cypermethrin on interleukin-6-induced androgen receptor activation.

To identify whether androgen receptor (AR) antagonism by cypermethrin involves interleukin-6 (IL-6)-induced ligand-independent AR signaling, we have developed the AR reporter gene assay. The reporter gene plasmid pMMTV-chloramphenicol transferase (CAT) was transfected into LNCaP cells. IL-6 increased expression of MMTV-CAT significantly (P<0.05). Cypermethrin decreased CAT reporter expression induced by IL-6 (50 ng/ml), and the significant inhibition was detected at 10(-5)M (P<0.05). IL-6 induces ligand-independent activation of AR. Cypermethrin exhibits inhibitory effects on IL-6-induced ligand-independent AR signaling. We provide a novel insight into cypermethrin-mediated antagonism of the IL-6-mediated ligand-independent activation of the AR.

Anti-androgen effects of the pyrethroid pesticide cypermethrin on interactions of androgen receptor with corepressors.

To clarify whether the mechanism of androgen receptor (AR) antagonism of the pyrethroid pesticide cypermethrin associates with the interactions between the AR and corepressors silencing mediator for thyroid hormone receptors (SMRT) and nuclear receptor corepressor (NCoR), we have developed the mammalian two-hybrid assays. The AR N-terminal domain 1-660 amino acid residues were subcloned into the plasmid pVP16 to construct VP16-ARNTD. The C-terminal receptor interaction domains (RIDs) of SMRT and NCoR were used to construct pM-SMRT and pM-NCoR. The constructed vectors pVP16-ARNTD, pM-SMRT or pM-NCoR, the reporter pG5CAT and the control pCMVß were cotranfected into the CV-1 cells. The cells were treated with cypermethrin at the indicated concentrations. The AR N terminus interacted with RIDs of SMRT and NCoR. The interactions between the AR and corepressors SMRT and NCoR were enhanced by cypermethrin, and the significant enhancement was detected at the concentration of 10(-5)M. The mammalian two-hybrid assays demonstrate the utility to detect the interactions of the AR with SMRT and NCoR. Cypermethrin functions as an anti-androgen by enhancing the associations of the AR with SMRT and NCoR. We provide a novel mechanism in anti-androgen action of cypermethrin associated with the recruitment of SMRT and NCoR to AR.

Identification of susceptibility genes in non-syndromic cleft lip with or without cleft palate using whole-exome sequencing

BACKGROUND: Non-syndromic cleft lip with or without cleft palate (NSCL/P) is among the most common congenital malformations. The etiology of NSCL/P remains poorly characterized owing to its complex genetic heterogeneity. The objective of this study was to identify genetic variants that increase susceptibility to NSCL/P. MATERIAL AND METHODS: Whole-exome sequencing (WES) was performed in 8 fetuses with NSCL/P in China. Bioinformatics analysis was performed using commercially available software. Variants detected by WES were validated by Sanger sequencing. RESULTS: By filtering out synonymous variants in exons, we identified average 8575 nonsynonymous single nucleotide variants (SNVs). We subsequently compared the SNVs against public databases including NCBI dbSNP build 135 and 1000 Genomes Project and obtained an average of 203 SNVs. Total 12 reported candidate genes were verified by Sanger sequencing. Sanger sequencing also confirmed 16 novel SNVs shared by two or more samples. CONCLUSIONS: We have found and confirmed 16 susceptibility genes responsible for NSCL/P, which may play important role in the etiology of NSCL/P. The susceptibility genes identified in this study will not only be useful in revealing the etiology of NSCL/P but also in diagnosis and treatment of the patients with NSCL/P