Deformation mechanisms of carbon nanotube fibres under tensile loading by in situ Raman spectroscopy analysis.

Deformation mechanisms of carbon nanotube (CNT) fibres under tensile loading are studied by means of in situ Raman spectroscopy to detect the CNT deformation and stress distributions in the fibres. The G' band in the Raman spectrum responds distinctly to the tensile stress in Raman shift, width and intensity. The G' band changes with the tensile deformation of the fibre at different stages, namely elastic deformation, strengthening and damage-fracture. It is deduced that the individual CNTs only deform elastically without obvious damage or bond breaking. The yield and fracture of fibres can be due to the slippage among the CNTs.

circASS1 overexpression inhibits the proliferation, invasion and migration of colorectal cancer cells by regulating the miR-1269a/VASH1 axis.

Colorectal cancer (CRC), the third most common cancer worldwide, poses a threat to human life. However, its underlying mechanism is unclear and no satisfactory treatment is available. The present study aimed to investigate the role of circular RNA argininosuccinate synthase 1 (circASS1) in CRC cells and tissues to identify the potential mechanism underlying the pathogenesis of CRC. The expression of circASS1 in CRC cells and tissues was determined by reverse transcription-quantitative PCR. Following circASS1 overexpression in HT29 cells, cell viability, colony formation and apoptosis were measured using MTT, colony formation and TUNEL assays, respectively. Cell invasion and migration were also assessed. After confirming the associations among circASS1, microRNA (miR)-1269a and vasohibin 1 (VASH1), the characteristics of the HT29 cell line were assessed by performing the aforementioned assays. circASS1 expression was decreased in CRC cells and tissues, and circASS1 overexpression suppressed CRC cell proliferation, invasion and migration. circASS1 adsorbed miR-1269a and regulated its expression, and VASH1 was a target protein of miR-1269a. circASS1 overexpression decreased cell proliferation, invasion and migration, but enhanced cell apoptosis in HT29 cells, which was reversed by co-transfection with miR-1269a mimic or short hairpin RNA-VASH1. In conclusion, circASS1 overexpression inhibited CRC cell proliferation, invasion and migration by regulating miR-1269a/VASH1, which indicated a potential molecular mechanism underlying the pathogenesis of CRC.

Nano-yarn carbon nanotube fiber based enzymatic glucose biosensor.

A novel brush-like electrode based on carbon nanotube (CNT) nano-yarn fiber has been designed for electrochemical biosensor applications and its efficacy as an enzymatic glucose biosensor demonstrated. The CNT nano-yarn fiber was spun directly from a chemical-vapor-deposition (CVD) gas flow reaction using a mixture of ethanol and acetone as the carbon source and an iron nano-catalyst. The fiber, 28 microm in diameter, was made of bundles of double walled CNTs (DWNTs) concentrically compacted into multiple layers forming a nano-porous network structure. Cyclic voltammetry study revealed a superior electrocatalytic activity for CNT fiber compared to the traditional Pt-Ir coil electrode. The electrode end tip of the CNT fiber was freeze-fractured to obtain a unique brush-like nano-structure resembling a scale-down electrical 'flex', where glucose oxidase (GOx) enzyme was immobilized using glutaraldehyde crosslinking in the presence of bovine serum albumin (BSA). An outer epoxy-polyurethane (EPU) layer was used as semi-permeable membrane. The sensor function was tested against a standard reference electrode. The sensitivities, linear detection range and linearity for detecting glucose for the miniature CNT fiber electrode were better than that reported for a Pt-Ir coil electrode. Thermal annealing of the CNT fiber at 250 degrees C for 30 min prior to fabrication of the sensor resulted in a 7.5 fold increase in glucose sensitivity. The as-spun CNT fiber based glucose biosensor was shown to be stable for up to 70 days. In addition, gold coating of the electrode connecting end of the CNT fiber resulted in extending the glucose detection limit to 25 microM. To conclude, superior efficiency of CNT fiber for glucose biosensing was demonstrated compared to a traditional Pt-Ir sensor.

Comparison of depression and anxiety between HIV-negative men who have sex with men and women (MSMW) and men who have sex with men only (MSMO): a cross-sectional study in Western China.

OBJECTIVE: To compare the prevalence of depression, anxiety and comorbidity between HIV-negative men who have sex with men and women (MSMW) and men who have sex with men only (MSMO) and examine the associated factors with depression and anxiety separately. DESIGN: A cross-sectional study. SETTING: The study was conducted in Western China. PARTICIPANTS: From April 2013 to October 2014, 2422 participants aged 18-65 years, who were male at birth, had engaged in sex with male partners in the past 6 months, self-reported negative or unknown HIV status, were willing to participate and provided informed consent were recruited using non-probability sampling. An anonymous self-administered questionnaire was used to collect the data. A total of 1809 HIV-negative men who have sex with men (MSM) were eligible for the final analysis. RESULTS: Of 1809 MSM, 16.1% were MSMW and 83.9% were MSMO. The prevalence of depression, anxiety and comorbidity was 50.86%, 36.43% and 32.65%, respectively, for MSMW; these results were higher than those for MSMO (35.18%, 23.52% and 18.91%, respectively). After adjusting for potential confounding factors, the prevalence of depression and anxiety was higher among MSMW than among MSMO. The prevalence of depression and/or anxiety was associated with young age, lower educational level, lower monthly income, lower HIV score and some risky sexual behaviour (had never engaged in HIV counselling, had obtained commercial sexual services in the past 6 months and sometimes/always looked for sexual partners through the internet). The prevalence of depression and anxiety was lower for those who drank less than once a week than for those who never drank. CONCLUSION: Our findings suggest the need to address mental health among MSMW. Future health intervention strategies should integrate mental health services and traditional HIV prevention programmes and should consider the differences between MSMW and MSMO. TRIAL REGISTRATION NUMBER: ChiCTR-TRC-13003849; Pre-results.

Transforming growth factor-beta1 enhanced vascular endothelial growth factor synthesis in mesenchymal stem cells.

Angiogenesis is essential for transplantation of mesenchymal stem cells (MSCs). Vascular endothelial growth factor (VEGF) is one of the most potent angiogenic factors identified to date. Elevated VEGF levels in MSCs correlate with the potential of MSCs transplantation. As an indirect angiogenic agent, transforming growth factor-beta1 (TGF-beta1) plays a pivotal role in the regulation of vasculogenesis and angiogenesis. However, the effect of TGF-beta1 on VEGF synthesis in MSCs is still unknown. Besides, the intracellular signaling mechanism by which TGF-beta1 stimulates this process remains poorly understood. In this article, we demonstrated that exposure of MSCs to TGF-beta1 stimulated the synthesis of VEGF. Meanwhile, TGF-beta1 stimulated the phosphorylation of Akt and extracellular signal-regulated kinase 1/2 (ERK1/2). Moreover, Ly 294002, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K)/Akt significantly attenuated the VEGF synthesis stimulated by TGF-beta1. Additionally, U0126, a specific inhibitor of ERK1/2, also significantly attenuated the TGF-beta1-stimulated VEGF synthesis. These results indicated that TGF-beta1 enhanced VEGF synthesis in MSCs, and the Akt and ERK1/2 activation were involved in this process.

Socio-demographics, sexual behaviours, and use of HIV prevention services among men who have sex with men and women in Western China.

This paper looks into the differences of sexual risk behaviours and prevention services among men who have sex with men and women and men who have sex with men only. The data from a cross-sectional survey of 159 men who have sex with men and women and 1186 men who have sex with men only in western China is analysed. It is found that men who have sex with men and women, with multiple anal sex partners, have higher rates of selling and buying sex than men who have sex with men only, but obtain less HIV-related knowledge from partners or HIV consulting and testing services. More efforts should be made to promote safer sexual behaviours and reduce the barriers for access to health services.

Fabrication of a multifunctional carbon nanotube "cotton" yarn by the direct chemical vapor deposition spinning process.

A continuous cotton-like carbon nanotube fiber yarn, consisting of multiple threads of high purity double walled carbon nanotubes, was fabricated in a horizontal CVD gas flow reactor with water vapor densification by the direct chemical vapor deposition spinning process. The water vapor interaction leads to homogeneous shrinking of the CNT sock-like assembly in the gas flow. This allows well controlled continuous winding of the dense thread inside the reactor. The CNT yarn is quite thick (1-3 mm), has a highly porous structure (99%) while being mechanically strong and electrically conductive. The water vapor interaction leads to homogeneous oxidation of the CNTs, offering the yarn oxygen-functionalized surfaces. The unique structure and surface of the CNT yarn provide it multiple processing advantages and properties. It can be mechanically engineered into a dense yarn, infiltrated with polymers to form a composite and mixed with other yarns to form a blend, as demonstrated in this research. Therefore, this CNT yarn can be used as a "basic yarn" for various CNT based structural and functional applications.