Showing papers by "Lifeng Yan published in 2014"
TL;DR: In this paper, a three-dimensional hydrogel of reduced graphene oxide and MnO2 nanoparticles has been prepared by a two-step synthesis, and the asymmetric supercapacitor exhibited a high performance with an energy density of 21.2 W h kg−1 and a power density of 0.82 kWkg−1, and it can be cycled reversibly in a wide potential window of 1.6 V (0-1.6V).
Abstract: A three-dimensional hydrogel of graphene and MnO2 nanoparticles has been prepared by a two-step synthesis. At first, nanoparticles of MnO2 were grown onto both surfaces of nanosheets of graphene oxide with the aid of benzyl alcohol in an aqueous suspension, and then the composite hydrogel of reduced graphene oxide (rGO) and MnO2 was prepared by a reduction-induced in situ self-assembly. Then, asymmetric supercapacitors with high energy and power densities were fabricated using the MnO2/rGO hydrogel as the positive electrode and a pure rGO hydrogel as the negative electrode in a neutral aqueous Na2SO4 (1.0 M) electrolyte. The asymmetric supercapacitor exhibited a high performance with an energy density of 21.2 W h kg−1 and a power density of 0.82 kW kg−1, and it can be cycled reversibly in a wide potential window of 1.6 V (0–1.6 V). The asymmetric supercapacitor also exhibited stable cycling performance with 89.6% capacitance after 1000 cycles. This work provides a new method for the preparation of a metal oxide/graphene hydrogel-based asymmetric supercapacitor free of polymer binders and conducting additives.
203 citations
TL;DR: In this paper, the self-assembly of chitosan chains with graphene oxide (GO) nanosheets has been studied, where GO works as the two-dimensional crosslinker dues to its multifunctional groups on both sides.
Abstract: Biomass-based materials are attractive due to their renewability, biodegradability, and biocompatibility. Chitosan is a typical biomacromolecule that can be used as feedstock for novel materials. Here, the self-assembly of chitosan chains with graphene oxide (GO) nanosheets has been studied, where GO works as the two-dimensional cross-linker dues to its multifunctional groups on both sides. Supramolecular hydrogels of chitosan and GO have been prepared by controlling the concentration of GO, ratio of chitosan to GO, and temperature. It was found that at high GO concentration, hydrogel can be obtained at room temperature, and the as-prepared hydrogel showed a self-healing performance. However, at low GO concentration, the supramolecular hydrogel formed only at high temperature (95 °C). The driving force for the hydrogel is believed to be the noncovalent interactions. The reversible hydrogels have potential applications in fields of biomaterials, wastewater treatment, and smart materials.
107 citations
TL;DR: In this paper, a simple and effective method for the fabrication of a flexible macroporous 3D graphene sponge using an ice template is developed in order to recover from a 50% deformation.
Abstract: A simple and effective method for the fabrication of a flexible macroporous 3D graphene sponge using an ice template is developed in this work. It was found that the porous structures of the 3D graphene architecture depended on the rate of ice crystal formation. At a low cooling rate, the inner walls of the graphene hydrogel were re-assembled into a hierarchical macroporous structure by the as-formed ice crystals, resulting in the formation of a macroporous graphene sponge after freeze-drying. The as-prepared graphene sponge was flexible and could recover from a 50% deformation. When the graphene sponge was used as the anode of a microbial fuel cell (MFC), the maximum power density reached 427.0 W m−3, which was higher than that of the MFC fabricated using carbon felt as the anode material. The macroporous structure of the graphene sponge ensured the microbes more easily diffused and propagated inside the materials, resulting in higher MFC performance.
84 citations
TL;DR: Seminal SOD activity was positively associated with sperm concentration and overall motility, whereas inversely with sperm DNA fragmentation, and genetic and non-genetic factors contributing to the determination of S OD activity in infertile men were assessed.
Abstract: Superoxide dismutase (SOD) is an important component of antioxidative defense systems and plays an important role in protecting spermatozoa from oxidative damage. In this study, we assessed seminal SOD activity, its association with semen parameters, and also genetic and non-genetic factors contributing to the determination of SOD activity in infertile men. Semen samples were obtained from 435 male infertility patients. Sperm DNA damage levels were detected with the Tdt-mediated dUTP nick end labelling (TUNEL) assay. Four single nucleotide polymorphisms (SNPs) in SOD2 and SOD3 genes were genotyped using OpenArray platform. We found that seminal SOD activity was positively associated with sperm concentration and overall motility, whereas inversely with sperm DNA fragmentation. In addition, infertile men with SOD2 rs4880 CC variants showed a low level of SOD activity when compared with TT carriers (Mean ± SD: 268.3 ± 102.3 and 342.8 ± 98.2, respectively, P = 0.005). Those who consumed vitamin C/E (≥3 times per week) had a significantly higher SOD activity level than those who did not (mean ± SD: 379.8 ± 93.3 and 332.2 ± 94.9, respectively, P = 0.001). Seminal SOD activity and other factors influencing SOD activity play a role in determining sperm fertilization potential and male infertility.
63 citations
TL;DR: In this article, a simple method has been developed to degrade the cellulose chains in its homogeneous solution in free of any noble or transition metal catalysts, and the homogeneous alkaline aqueous solution of cellulose was prepared at first, and then it was hydrothermally degraded at 160-300 °C.
Abstract: Conversion of cellulose to chemicals or fuels is the key point for the utilization of biomass to substitute for fossil resources. Here, a simple method has been developed to degrade the cellulose chains in its homogeneous solution in free of any noble or transition metal catalysts. The homogeneous alkaline aqueous solution of cellulose was prepared at first, and then it was hydrothermally degraded at 160–300 °C . Malonic acid (MA), lactic acid (LA), formic acid (FA), and acetic acid (AA) are the major valuable products, among them MA and LA are the top valuable platform molecules for synthesis of bulk chemicals and fuels. The maximum yield of MA is 39.7%, and the maximum total yield of the four kinds of organic acid is 81.2%. In addition, it is the first report that cellulose can be directly degraded to MA in a simple chemical route.
44 citations
TL;DR: It is demonstrated that the risk of developing bladder cancer in transplant populations was increased, which suggests that physicians should be more vigilant in checking for bladdercancer in transplantation recipient population.
Abstract: Renal transplantation has been associated with a significantly increased risk of developing cancers during long-term follow-up, but for bladder cancer, this risk is less clear. We therefore performed a meta-analysis to determine whether bladder cancer risk in renal transplant recipients was increased. Eligible studies were identified through searches of PubMed and other public resources. Random-effects meta-analyses were used to pool overall estimates for standardised incidence ratios (SIRs). Heterogeneity test, sensitivity analysis, and assessment of publishing bias were also performed. We identified a 3.18-fold higher SIR (95% confidence intervals (CI): 1.34–7.53, P=0.008) of bladder cancer in patients following renal transplantation compared with the general population, based on data from 79 988 patients with a total follow-up of 308 458 patient-years. When stratified by ethnicity, the SIRs for bladder cancer were 2.00 (95% CI: 1.51–2.65, P=0.001) and 14.74 (95% CI: 3.66–59.35, P<0.001) between European and Asian renal transplant recipients, respectively. Our study demonstrated that the risk of developing bladder cancer in transplant populations was increased. Such association suggests that physicians should be more vigilant in checking for bladder cancer in transplantation recipient population.
39 citations
TL;DR: The results give the first evidence that genetic variations of TERT rs2736100 and TEP1 rs1713449 were associated with susceptibility to male infertility.
31 citations
TL;DR: Liver transplant recipients are at higher risk of developing head and neck cancer than the general population, and no heterogeneity or publication bias was observed.
Abstract: It is unclear whether liver transplantation is associated with an increased incidence of post-transplant head and neck cancer. This comprehensive meta-analysis evaluated the association between liver transplantation and the risk of head and neck cancer using data from all available studies. PubMed and Web of Science were systematically searched to identify all relevant publications up to March 2014. Standardized incidence ratio (SIR) and 95% confidence intervals (CIs) for risk of head and neck cancer in liver transplant recipients were calculated. Tests for heterogeneity, sensitivity, and publishing bias were also performed. Of the 964 identified articles, 10 were deemed eligible. These studies included data on 56,507 patients with a total follow-up of 129,448.9 patient-years. SIR for head and neck cancer was 3.836-fold higher (95% CI 2.754–4.918, P = 0.000) in liver transplant recipients than in the general population. No heterogeneity or publication bias was observed. Sensitivity analysis indicated that omission of any of the studies resulted in an SIR for head and neck cancer between 3.488 (95% CI: 2.379–4.598) and 4.306 (95% CI: 3.020–5.592). Liver transplant recipients are at higher risk of developing head and neck cancer than the general population.
22 citations
TL;DR: Of five NOS gene polymorphisms investigated in the present study, NOS3 rs1799983 might cause oxidative sperm DNA damage, thereby contributing to male infertility.
Abstract: Background
In recent years, oxidative stress has been studied extensively as a main contributing factor to male infertility. Nitric Oxide, a highly reactive free radical gas, is potentially detrimental to sperm function and sperm DNA integrity at high levels. Thus, the aim of this study was to investigate the associations between five polymorphisms in nitric oxide synthase genes (NOSs) and the risk of male infertility and sperm DNA damage as well.
17 citations
TL;DR: The obtained NIRF copolymer and its micelles were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), dynamic light scattering (DLS), and UV-vis and fluorescence spectrophotometry, and it has potential application in the theranostics of cancer.
Abstract: A novel amphiphilic multi-block copolymer conjugated with both a near infrared fluorescence probe and drug has been designed and prepared by means of ring-opening polymerization (ROP) of N-Carboxy Anhydride (NCA) monomers following a Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization. At first, an amino group-containing RAFT agent was synthesized and it served as an initiator for the sequential ROP of aspartic acid β-benzyl ester N-carboxy anhydride (Asp-NCA) and e-carbobenzoxy-L-lysine NCA (ZLLys-NCA). Then the multi-block copolymer was prepared by a succeeding RAFT polymerization of poly(ethylene glycol) methyl ether acrylate (OGEA). At the end, both anticancer drug doxorubicin and hydrophobic aminocyanine dye were chemical conjugated to the block copolymer via a hydrazone or amide bond, respectively. The obtained NIRF copolymer and its micelles were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), dynamic light scattering (DLS), and UV-vis and fluorescence spectrophotometry. The prodrug has strong fluorescence in the near infrared region and shows pH-responsive drug release behavior, and it has potential application in the theranostics of cancer.
10 citations
TL;DR: In this article, a primary battery with a Zn plate as the anode and a centimeter-sized dried foam film of graphene oxide (GO) as the cathode has been fabricated, and the electron-output has been achieved while a reduced graphene oxidised film was obtained synchronously.
Abstract: The reduction of graphene oxide (GO) by zinc powder is essentially an electron-input process. Is it possible to output the electron during the reduction for a primary battery? Here, a primary battery with a Zn plate as the anode and a centimeter-sized dried foam film of graphene oxide (GO) as the cathode has been fabricated, and the electron-output has been achieved while a reduced graphene oxidised film was obtained synchronously. The output capacity of the batteries depends on the oxygenated degree and the amount of GO, and the maximum specific capacity is 642 mA h g−1, while the average voltage is up to 0.6 V. Electrochemical impedance spectroscopy (EIS) measurements revealed the decreasing resistance of the Zn/GO cell during the discharging process. An LED lamp can be lit by the battery, indicating its potential for practical applications. In addition, the primary battery is MnO2-free, and hence is more environmentally benign than the traditional Zn/Carbon dry batteries.
Patent•
02 Jul 2014
TL;DR: In this article, a method for detecting plasmids of polycyclic aromatic hydrocarbons in an environment and an application thereof, and relates to the fields of molecular biology and environmental biotechnology.
Abstract: The invention discloses a method for detecting plasmids of polycyclic aromatic hydrocarbons in an environment and an application thereof, and relates to the fields of molecular biology and environmental biotechnology. According to the method provided by the invention, by extracting the promoter of a humanized AHR (Aromatic Hydrocarbon Receptor) gene, using a CV060 plasmid including a firefly luciferase and renilla luciferase reporter gene as a carrier and inserting the AHR gene promoter with a specific sequence, a recombined lentivirus plasmid of a reference internal type dual-luciferase reporter gene including the AHR gene promoter is built. The detection method provided by the invention is good in repeatability, high in sensitivity, reliable in detection result, and simple and convenient to operate, and can be widely applied to the detection of the polycyclic aromatic hydrocarbons in the environment.