Huimin Tian

Ar plasma treatment on few layer graphene sheets for enhancing their field emission properties

Plasma treatment in Ar gas on few layer graphene sheets (FLGSs), synthesized by plasma enhanced chemical vapour deposition, has been performed for enhancing their field emission properties. The plasma etching treatment for 3?min on the FLGSs, forming an extremely sharp edge, decreases the turn-on electric field from 3.91 to 2.23?V??m?1, and increases the maximum emission current density, drawn at a field of 4.4?V??m?1, from 33 to 1330??A?cm?2. It is expected that plasma treatment provides an efficient way to improve the field emission properties of FLGSs.

Synthesis of graphene on a polycrystalline Co film by radio-frequency plasma-enhanced chemical vapour deposition

Graphene of 1–5 layers was synthesized on a polycrystalline Co film by radio-frequency plasma-enhanced chemical vapour deposition at a relatively low temperature of 800 ◦ C for only 40 s in a mixture of gases of CH4/H2/Ar (1/5/20, with a total gas flow rate of 78 sccm). The obtained graphene is of high quality as revealed by Raman spectroscopy and x-ray photoelectron spectroscopy. It exhibits a high optical transmittance of more than 70% in the wavelength range 500–1200 nm, and a sheet resistivity of 2661 � /sq. A possible formation mechanism is proposed. The significant influence of octahedral and tetrahedral lattice interstitial sites in the Co crystallites on the formation of graphene is discussed. (Some figures in this article are in colour only in the electronic version)

Low-dose radiation may be a novel approach to enhance the effectiveness of cancer therapeutics

It has been generally accepted that both natural and man‐made sources of ionizing radiation contribute to human exposure and consequently pose a possible risk to human health. However, accumulating evidence has shown that the biological effects of low‐dose radiation (LDR) are different from those of high‐dose radiation. LDR can stimulate proliferation of normal cells and activate their defense systems, while these biological effects are not observed in some cancer cell types. Although there is still no concordance on this matter, the fact that LDR has the potential to enhance the effects of cancer therapeutics and reduce the toxic side effects of anti‐cancer therapy has garnered significant interest. Here, we provide an overview of the current knowledge regarding the experimental data detailing the different responses of normal and cancer tissues to LDR, the underlying mechanisms, and its significance in clinical application.

Synthesis and field electron emission properties of hybrid carbon nanotubes and nanoparticles

Hybrid ZnO-carbon nanotubes as well as nanodiamond-carbon nanotubes were synthesized via a straightforward process of plasma enhanced chemical vapor deposition. For the former, ZnO nanoparticles were instantly coated on the tube surface in the final growing process of carbon nanotubes, while for the latter diamond nanoparticles were grown using pretreatment of a silicon substrate with Ni(NO(3))(2)·6H(2)O/Mg(NO(3))(2)·6H(2)O alcohol solution prior to deposition and a high H(2)/CH(4) gas flow ratio in the deposition process. The morphology and microstructure of the obtained hybrid materials were characterized by transmission electron microscopy. Both hybrid ZnO-carbon nanotubes and nanodiamond-carbon nanotubes exhibited excellent field emission properties.

Influence of oxygen on the growth of carbon nanotubes

The influence of oxygen on the growth of carbon nanotubes (CNTs) using plasma-enhanced chemical vapour deposition has been studied. The cobalt catalyst film and CNTs were characterized by scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscope, x-ray photoelectron spectroscopy and Raman spectroscopy. The results showed that small cobalt oxide particles obtained by O2-etching were deoxidized back to Co catalyst particles with small size in the CH4/H2 atmosphere for the growth of CNTs. Small Co particles and the inlet of oxygen in the stage of CNT growth enhanced the yield rate and purity of aligned CNTs.

Amorphous hollow carbon spheres synthesized using radio frequency plasma-enhanced chemical vapour deposition

We report a method to synthesize amorphous hollow carbon spheres, with diameters ranging from 100 to 800?nm, which are dispersed among bent graphitized carbon nanotubes using radio frequency plasma-enhanced chemical vapour deposition in mixed CH4/H2 gases. The products are characterized by techniques including scanning electron microscopy, energy-dispersive x-ray spectroscopy, Raman spectroscopy and transmission electron microscopy. It is found that MgO and Ni nanoparticles together with hydrogen play important roles in the formation of the spheres. A possible formation mechanism for the carbon composites has been proposed.

Prognostic value of MICA/B in cancers: a systematic review and meta-analysis

Purpose MHC class I chain related-proteins A (MICA) and B (MICB) are natural killer group 2D ligands that mediate tumor surveillance. Several studies have suggested that MICA/B levels predict clinical outcomes in patients with cancer; however, this remains contentious. Here, we present a systematic review and meta-analysis of available studies of the prognostic value of MICA/B in cancer. Materials and Methods We searched PubMed, Embase, Clinicaltrials.gov, and Cochrane Library to identify studies published from inception to July 2017 that assessed MICA/B in patients with cancer. The hazard ratio (HR) and 95% confidence interval (CI) of MICA/B were extracted for overall survival (OS) analysis. Results A total of 19 studies comprising 2,588 patients with 10 different types of cancer were included in the study. Low sMICA/B levels were found associated with significantly longer OS (HR = 1.65, 95% CI [1.42–1.92], P < 0.00001). Patients with cancers of digestive system that exhibited high MICA/B expression had significantly longer OS in (HR = 0.56, 95% CI [0.39–0.80], P = 0.002) compared with those with lower MICA/B expression (I2 = 35%, P = 0.18). Conclusions Serum soluble MICA/B represents a potential prognostic marker in various human cancers. High cell-surface MICA/B expression in cancers of the digestive system was found associated with increased survival.

Significant benefits of adding neoadjuvant chemotherapy before concurrent chemoradiotherapy for locoregionally advanced nasopharyngeal carcinoma: a meta-analysis of randomized controlled trials

Purpose We did a meta-analysis to compare the efficacy and safety of neoadjuvant chemotherapy (NACT) followed by concurrent chemoradiotherapy (CCRT) versus CCRT with or without adjuvant chemotherapy (AC) for patients with locoregionally advanced nasopharyngeal carcinoma based on randomized controlled trials. Methods We searched PubMed, Embase, Web of Science, ClinicalTrials.gov, Chinese National Knowledge Infrastructure, and meeting proceedings of major relevant conferences to identify published and unpublished randomized controlled trials. Progression-free survival (PFS) was the primary endpoint. Results This meta-analysis included 9 randomized clinical trials with 2215 patients. NACT followed by CCRT significantly improved PFS (HR=0.68, 95% CI 0.56 – 0.81, P < 0.001) compared versus CCRT with or without AC, and no heterogeneity was observed (I2 = 0.0%, P = 0.975). NACT was associated with a significant improvement in overall survival (HR = 0.64, 95% CI 0.49 – 0.84, P = 0.001; I2 = 0.0%, P = 0.467) and distant failure-free survival (HR = 0.72, 95% CI 0.53 – 0.97, P = 0.031; I2 = 0.0%, P = 0.744). No significant benefit was shown by NACT for locoregional control. NACT with CCRT increased risks of grade 3 – 4 anemia, thrombocytopenia, leukopenia, and fatigue, compared versus CCRT with or without AC. Conclusions Our meta-analysis confirmed that the addition of NACT to CCRT significantly improved PFS and OS versus CCRT with or without AC for locoregionally advanced nasopharyngeal carcinoma. These results may alter the standard of care - CCRT with or without AC, for locoregionally advanced nasopharyngeal carcinoma.

Distinct biological effects of low-dose radiation on normal and cancerous human lung cells are mediated by ATM signaling

Low-dose radiation (LDR) induces hormesis and adaptive response in normal cells but not in cancer cells, suggesting its potential protection of normal tissue against damage induced by conventional radiotherapy. However, the underlying mechanisms are not well established. We addressed this in the present study by examining the role of the ataxia telangiectasia mutated (ATM) signaling pathway in response to LDR using A549 human lung adenocarcinoma cells and HBE135-E6E7 (HBE) normal lung epithelial cells. We found that LDR-activated ATM was the initiating event in hormesis and adaptive response to LDR in HBE cells. ATM activation increased the expression of CDK4/CDK6/cyclin D1 by activating the AKT/glycogen synthase kinase (GSK)-3β signaling pathway, which stimulated HBE cell proliferation. Activation of ATM/AKT/GSK-3β signaling also increased nuclear accumulation of nuclear factor erythroid 2-related factor 2, leading to increased expression of antioxidants, which mitigated cellular damage from excessive reactive oxygen species production induced by high-dose radiation. However, these effects were not observed in A549 cells. Thus, the failure to activate these pathways in A549 cells likely explains the difference between normal and cancer cells in terms of hormesis and adaptive response to LDR.

Single Nucleotide Polymorphism rs1801516 in Ataxia Telangiectasia-Mutated Gene Predicts Late Fibrosis in Cancer Patients After Radiotherapy: A PRISMA-Compliant Systematic Review and Meta-Analysis.

AbstractStudies on associations between ataxia telangiectasia-mutated (ATM) polymorphisms and late radiotherapy-induced adverse events vary in clinical settings, and the results are inconsistent.We conducted the first meta-analysis following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to investigate the role of the ATM polymorphism rs1801516 in the development of radiotherapy-induced late fibrosis.We searched PubMed, Embase, Web of Science, and Chinese National Knowledge Infrastructure databases to identify studies that investigated the effect of the ATM polymorphism rs1801516 on radiotherapy-induced late fibrosis before September 8, 2015. Summary odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were used to assess the association between late fibrosis and the rs1801516 polymorphism. Subgroup analyses were conducted to evaluate the influence of clinical features on the genetic association. Tests of interaction were used to compare differences in the effect estimates between subgroups.The overall meta-analysis of 2000 patients from 9 studies showed that the minor allele of the rs1801516 polymorphism was associated with a significantly increased risk of developing late fibrosis (OR = 1.78, 95% CI: 1.07, 2.94), with high between-study heterogeneity (I2 = 66.6%, P = 0.002). In subgroup analyses, we identified that the incidence of late fibrosis was a major source of heterogeneity across studies. The OR for patients with a high incidence of late fibrosis was 3.19 (95% CI: 1.86, 5.47), in contrast to 1.09 (95% CI: 1.01, 1.17) for those with a low incidence. There was a significant difference in the effect estimates between the 2 subgroups (ratio of OR = 2.94, 95% CI 1.70, 5.08, P = 0.031).This meta-analysis supported previously reported effect of the ATM polymorphism rs1801516 on radiotherapy-induced late fibrosis. This finding encouraged further researches to identify more genetic polymorphisms that were predictive for radiotherapy-induced adverse events. In addition, we showed that the inconsistency of the associations seen in these studies might be related to variations in the incidence of late fibrosis in the patients. This suggested that future studies should consider the incidence of radiotherapy-induced adverse events when investigating radiosensitivity signature genes.