Wang, Guangshuo; Ma, Yingying; Dong, Xufeng; Tong, Yu; Zhang, Lina; Mu, Jingbo; Bai, Yongmei; Hou, Junxian; Che, Hongwei; Zhang, Xiaoliang
In this study, cobalt ferrite/graphene oxide (CoFe2O4/GO) nanocomposites were synthesized successfully by a facile sonochemical method. The microstructure and physical properties of CoFe2O4/GO nanocomposites were investigated in detail by TEM, XRD and SQUID. It was found that GO nanosheets were fully exfoliated and decorated homogeneously with CoFe2O4 nanoparticles having diameters of 8∼15 nm. The field-dependent magnetization curve indicated superparamagnetic behavior of as-prepared CoFe2O4/GO with saturation magnetization (Ms) of 34.9 emu/g at room temperature. The ferrofluid was prepared by the obtained CoFe2O4/GO with 25 wt% particles and its magnetorheological (MR) properties were tested using a Physica MCR301 rheometer fitted with a magneto-rheological module. The CoFe2O4/GO-based ferrofluid exhibited typical MR effect with increasing viscosity, shear stress and yield stress depending on the applied magnetic field strength.
Ma, Shuanglong; Zhan, Sihui; Jia, Yanan; Zhou, Qixing
Ag-CoFe2O4-graphene oxide (Ag-CoFe2O4-GO) nanocomposite was synthesized by doping silver and CoFe2O4 nanoparticles on the surface of GO, which was used to purify both bacteria and Pb(II) contaminated water. The Ag-CoFe2O4-GO nanomaterial was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), cyclic voltammetry (CV), and magnetic property tests. It can be found that Ag-CoFe2O4-GO nanocomposite exhibited excellent antibacterial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus compared with CoFe2O4, Ag-CoFe2O4, and CoFe2O4-GO composite. This superior disinfecting effect was possibly attributed to the combination of GO nanosheets and Ag nanoparticles. Several antibacterial factors including temperature, time, and pH were also investigated. It was obvious that E. coli was more susceptible than S. aureus toward all the four types of nanomaterials. The structural difference of bacterial membranes should be responsible for the resistant discrepancy. We also found that Ag-CoFe2O4-GO inactivated both bacteria in an irreversibly stronger manner than Ag-CoFe2O4 and CoFe2O4-GO. The Pb(II) removal efficiency with all the nanomaterials showed significant dependence on the surface area and zeta potential of the materials. In this work, not only did we demonstrate the simultaneous superior removal efficiency of bacteria and Pb(II) by Ag-CoFe2O4-GO but also the antibacterial mechanism was discussed to have a better understanding of the interaction between Ag-CoFe2O4-GO and bacteria. In a word, taking into consideration the easy magnetic separation, bulk availability, and irreversibly high antibacterial activity of Ag-CoFe2O4-GO, it is the very promising candidate material for advanced antimicrobial or Pb(II) contaminated water treatment.
Van Auken, Kimberly; Schaeffer, Mary L.; McQuilton, Peter; Laulederkind, Stanley J. F.; Li, Donghui; Wang, Shur-Jen; Hayman, G. Thomas; Tweedie, Susan; Arighi, Cecilia N.; Done, James; Müller, Hans-Michael; Sternberg, Paul W.; Mao, Yuqing; Wei, Chih-Hsuan; Lu, Zhiyong
Gene function curation via Gene Ontology (GO) annotation is a common task among Model Organism Database groups. Owing to its manual nature, this task is considered one of the bottlenecks in literature curation. There have been many previous attempts at automatic identification of GO terms and supporting information from full text. However, few systems have delivered an accuracy that is comparable with humans. One recognized challenge in developing such systems is the lack of marked sentence-level evidence text that provides the basis for making GO annotations. We aim to create a corpus that includes the GO evidence text along with the three core elements of GO annotations: (i) a gene or gene product, (ii) a GO term and (iii) a GO evidence code. To ensure our results are consistent with real-life GO data, we recruited eight professional GO curators and asked them to follow their routine GO annotation protocols. Our annotators marked up more than 5000 text passages in 200 articles for 1356 distinct GO terms. For evidence sentence selection, the inter-annotator agreement (IAA) results are 9.3% (strict) and 42.7% (relaxed) in F1-measures. For GO term selection, the IAAs are 47% (strict) and 62.9% (hierarchical). Our corpus analysis further shows that abstracts contain ∼10% of relevant evidence sentences and 30% distinct GO terms, while the Results/Experiment section has nearly 60% relevant sentences and >70% GO terms. Further, of those evidence sentences found in abstracts, less than one-third contain enough experimental detail to fulfill the three core criteria of a GO annotation. This result demonstrates the need of using full-text articles for text mining GO annotations. Through its use at the BioCreative IV GO (BC4GO) task, we expect our corpus to become a valuable resource for the BioNLP research community. Database URL: http://www.biocreative.org/resources/corpora/bc-iv-go-task-corpus/. PMID:25070993
Doustkhah, Esmail; Rostamnia, Sadegh
Multistep synthesis of covalently sulfonated magnetic graphene oxide was achieved by starting from Hummer's method to produce graphene oxide (GO) from chemical oxidation of graphite. Then, GO nanosheets were applied to support Fe3O4 nanoparticles (Fe3O4@GO) using co-precipitation method in the presence of GO sheets. This strategy led to formation of uniform particles of Fe3O4 on the surface of GO sheets. Then, it was sulfonated (Fe3O4@GO-Pr-SO3H) through modification with 3-mercaptopropyltrimethoxysilane (MPTMS) and subsequent oxidation with hydrogen peroxide (H2O2). In comparison, the covalently bonded propyl sulfonic acid groups were more prevailing rather to sulfonic acids of GO itself. The proposed catalyst was more active and recyclable at least for 11 runs.
Doustkhah, Esmail; Rostamnia, Sadegh
Multistep synthesis of covalently sulfonated magnetic graphene oxide was achieved by starting from Hummer's method to produce graphene oxide (GO) from chemical oxidation of graphite. Then, GO nanosheets were applied to support Fe3O4 nanoparticles (Fe3O4@GO) using co-precipitation method in the presence of GO sheets. This strategy led to formation of uniform particles of Fe3O4 on the surface of GO sheets. Then, it was sulfonated (Fe3O4@GO-Pr-SO3H) through modification with 3-mercaptopropyltrimethoxysilane (MPTMS) and subsequent oxidation with hydrogen peroxide (H2O2). In comparison, the covalently bonded propyl sulfonic acid groups were more prevailing rather to sulfonic acids of GO itself. The proposed catalyst was more active and recyclable at least for 11 runs. PMID:27309948
Gene function curation via Gene Ontology (GO) annotation is a common task among Model Organism Database (MOD) groups. Due to its manual nature, this task is time-consuming and labor-intensive, and thus considered one of the bottlenecks in literature curation. There have been many previous attempts a...
Huang, Yanhua; Wang, Yuzhi; Pan, Qi; Wang, Ying; Ding, Xueqin; Xu, Kaijia; Li, Na; Wen, Qian
Four kinds of green deep eutectic solvents (DESs) based on choline chloride (ChCl) have been synthesized and coated on the surface of magnetic graphene oxide (Fe3O4@GO) to form Fe3O4@GO-DES for the magnetic solid-phase extraction of protein. X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM) and thermal gravimetric analysis (TGA) were employed to characterize Fe3O4@GO-DES, and the results indicated the successful preparation of Fe3O4@GO-DES. The UV-vis spectrophotometer was used to measure the concentration of protein after extraction. Single factor experiments proved that the extraction amount was influenced by the types of DESs, solution temperature, solution ionic strength, extraction time, protein concentration and the amount of Fe3O4@GO-DES. Comparison of Fe3O4@GO and Fe3O4@GO-DES was carried out by extracting bovine serum albumin, ovalbumin, bovine hemoglobin and lysozyme. The experimental results showed that the proposed Fe3O4@GO-DES performs better than Fe3O4@GO in the extraction of acidic protein. Desorption of protein was carried out by eluting the solid extractant with 0.005 mol L(-1) Na2HPO4 contained 1 mol L(-1) NaCl. The obtained elution efficiency was about 90.9%. Attributed to the convenient magnetic separation, the solid extractant could be easily recycled.
Liu, Mancheng; Wen, Tao; Wu, Xilin; Chen, Changlun; Hu, Jun; Li, Jie; Wang, Xiangke
A composite of porous Fe3O4 hollow microspheres/graphene oxide (Fe3O4/GO) has been fabricated through a facile self-assembly approach. Driven by the mutual electrostatic interactions, the amine-functionalized Fe3O4 microspheres prepared by a hydrothermal method and then modified by 3-aminopropyltrimethoxysilane were decorated with negatively-charged GO sheets. The Fe3O4 microspheres were hollow with porous surfaces and the surfaces were successfully modified with the amine, which was confirmed by Fourier transform infrared spectroscopy. The specific saturation magnetization of Fe3O4/GO was 37.8 emu g(-1). The sorption performance of Fe3O4/GO for Cr(vi) was evaluated. The maximum sorption capacity for Cr(vi) on Fe3O4/GO was 32.33 mg g(-1), which was much higher than that of Fe3O4 microspheres. The GO sheets could not only prevent agglomeration of the Fe3O4 microspheres and enable a good dispersion of these oxide microspheres, but also substantially enhance the specific surface area of the composite. The Fe3O4/GO composite may be a promising sorption material for the separation and preconcentration of heavy metal ions from aqueous solutions in environmental pollution cleanup. PMID:23743481
Douglass, Malcolm P., Ed.
The articles in this collection approach the theme of "Reading in the Age of the Computer" in a variety of ways. Topics covered in the 26 articles include the following: (1) children, school, and computers; (2) new kinds of electronic learning environments; (3) the personal computer for creative learning and thinking; (4) going beyond rote and…
The intricacies of Newton's Cradle are well covered in the literature2-4 going as far back as the time of Newton!5 These discussions generally center on the highly elastic collisions of metal spheres. Thanks to the invention of happy and unhappy balls,6 you can build and study the interaction of less elastic systems (see Fig. 1).
Ye, Nengsheng; Xie, Yali; Shi, Pengzhi; Gao, Ting; Ma, Jichao
In this study, a facile and novel strategy was developed to fabricate magnetite/graphene oxide/chitosan (Fe3O4/GO/CS) composite, and the composite was used as a magnetic adsorbent for the enrichment of protein, and followed by matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF MS) analysis. The phase composition, chemical structure and morphology of the composite were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), scanning electronic microscope (SEM) and vibrating sample magnetometer (VSM). Protein cytochrome c was chosen as model target to evaluate the adsorptive property of Fe3O4/GO/CS. After enrichment procedure and magnetic separation, protein bounded with the material was analyzed by MALDI-TOF MS without desorption. The results indicated that Fe3O4/GO/CS composite exhibited a good adsorptive capacity for protein, and Fe3O4/GO/CS composite had a promising potential in magnetic separation research.
Wang, Guangshuo; Ma, Yingying; Zhang, Lina; Mu, Jingbo; Zhang, Zhixiao; Zhang, Xiaoliang; Che, Hongwei; Bai, Yongmei; Hou, Junxian
In this study, manganese ferrite/graphene oxide (MnFe2O4/GO) nanocomposites as controlled targeted drug delivery were prepared by a facile sonochemical method. It was found that GO nanosheets were fully exfoliated and decorated with MnFe2O4 nanoparticles having diameters of 5-13 nm. The field-dependent magnetization curve indicated superparamagnetic behavior of the obtained MnFe2O4/GO with saturation magnetization of 34.9 emu/g at room temperature. The in vitro cytotoxicity testing exhibited negligible cytotoxicity of as-prepared MnFe2O4/GO even at the concentration as high as 150 μg/mL. Doxorubicin hydrochloride (DOX) as an anti-tumor model drug was utilized to explore the application potential of MnFe2O4/GO for controlled drug delivery. The drug loading capacity of this nanocarrier was as high as 0.97 mg/mg and the drug release behavior showed a sustained and pH-responsive way.
Peet, William, Jr.
This is the second of two volumes devoted to dialogs designed for classroom use by students of English as a second language. Survival skills are emphasized. The dialogs are grouped under the following titles: (1) "Buying Furniture," (2) "Straightening Metal Surfaces," (3) "Opening a Checking Account," (4) "Going to the Doctor," (5) "Building…
Xu, Zhiwei; Wu, Tengfei; Shi, Jie; Wang, Wei; Teng, Kunyue; Qian, Xiaoming; Shan, Mingjing; Deng, Hui; Tian, Xu; Li, Cuiyu; Li, Fengyan
Hybrid membranes blended with nanomaterials such as graphene oxide (GO) have great opportunities in water applications due to their multiple functionalities, but they suffer from low modification efficiency of nanomaterials due to the fact that plenty of the nanomaterials are embedded within the polymer matrix during the blending process. Herein, a novel Fe3O4/GO-poly(vinylidene fluoride) (Fe3O4/GO-PVDF) hybrid ultrafiltration membrane was developed via the combination of magnetic field induced casting and a phase inversion technique, during which the Fe3O4/GO nanocomposites could migrate toward the membrane top surface due to magnetic attraction and thereby render the surface highly hydrophilic with robust resistance to fouling. The blended Fe3O4/GO nanocomposites migrated to the membrane surface with the magnetic field induced casting, as verified by X-ray photoelectron spectroscopy, elemental analysis, and energy dispersive X-ray spectroscopy. As a result, the novel membranes exhibited significantly improved hydrophilicity (with a contact angle of 55.0°) and water flux (up to 595.39 L m(-2) h(-1)), which were improved by 26% and 206%, 12% and 49%, 25% and 154%, and 11% and 33% compared with those of pristine PVDF membranes and PVDF hybrid membranes blended with GO, Fe3O4, and Fe3O4/GO without the assistance of magnetic field during membrane casting, respectively. Besides, the novel membranes showed high rejection of bovine serum albumin (>92%) and high flux recovery ratio (up to 86.4%). Therefore, this study presents a novel strategy for developing high-performance hybrid membranes via manipulating the migration of nanomaterials to the membrane surface rather than embedding them in the membrane matrix. PMID:27355273
Ouyang, Ke; Zhu, Chuanhe; Zhao, Ya; Wang, Leichao; Xie, Shan; Wang, Qun
A reclaimable Fe3O4/graphene oxide (GO) magnetic hybrid was successfully synthesized via a facile one-pot polyol approach and employed as a recyclable adsorbent for Bisphenol A (BPA) in aqueous solutions. The maximum adsorption capacity (qm) of the Fe3O4/GO hybrid for BPA was 72.80 mg/g at 273 K. The kinetics of the adsorption process and the adsorption isotherm data were fitted using the Freundlich equation and a pseudo-second-order kinetic model. The results of the thermodynamic parameters ΔH°, ΔS° and ΔG° showed that the adsorption process was exothermic and spontaneous. Furthermore, the reusability of the samples was investigated, and the results indicated that the samples exhibited high stability. The magnetic characterization demonstrated that hybrids were superparamagnetic and could be recovered conveniently by magnetic separation. The strong π-π interaction was determined to be the predominant driving force behind the adsorption of BPA onto the Fe3O4/GO hybrid. Therefore, the Fe3O4/GO hybrid could be regarded as a potential adsorbent for wastewater treatment and purification processes.
Chen, Peng; Xing, Xiang; Xie, Huifang; Sheng, Qi; Qu, Hongxia
Magnetic CuFe2O4/graphene oxide composite (CuFe2O4/GO) has been synthesized by hydrothermal method and showed excellent visible-light-photocatalytic activity for the degradation of different dyes as Rhodamine B (RhB) and acid orange II (AO7) with no need of H2O2. The Structure and morphology were investigated by XRD, FTIR and TEM and the performance of the catalyst was systematically investigated under various experimental conditions as pH, the dosage of catalyst, dye initial concentration, etc. The dyes degradation on CuFe2O4/GO was also remained in a level in the presence of OH2- radical scavenger (2-propanol), while it decreased in the presence of O2- radical scavenger (benzoquinone) and h+ radical scavenger (ammonium oxalate), indicating that O2- and h+ radicals were responsible for the dye degradation. The magnetic CuFe2O4/GO composite shows potential applications in organic dye water treatment due to its magnetically recyclability and powerful visible-light-photocatalytic activity.
Shi, Penghui; Su, Ruijing; Zhu, Shaobo; Zhu, Mincong; Li, Dengxin; Xu, Shihong
The current paper investigated the removal of the azo dye Orange II from water using advanced oxidation processes based on sulfate radicals. The cobalt oxide catalyst immobilized on graphene oxide (GO) can activate peroxymonosulfate (PMS) for the degradation of Orange II in water. The Co(3)O(4)/GO catalyst system was characterized via X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and X-ray spectroscopy. Results showed that Co(3)O(4) was distributed on GO. The Co(3)O(4)/GO catalyst system exhibited high activity in Orange II oxidation when the Co(3)O(4)/GO catalyst has an optimum Co(3)O(4) loading. In addition, 100% decomposition could be achieved within 6 min with 0.2mM Orange II, 0.1 g L(-1) catalyst, and 2mM PMS. Meanwhile, inductively coupled plasma analysis revealed that the leach of cobalt ions was low. The catalyst also exhibited stable performance after several rounds of regeneration. Several operational parameters, such as catalyst amount, oxidant amount, pH, temperature, and oxidation rate, affected the degradation of Orange II. PMID:22738772
Mixed hemimicelles solid-phase extraction of cephalosporins in biological samples with ionic liquid-coated magnetic graphene oxide nanoparticles coupled with high-performance liquid chromatographic analysis.
Wu, Jianrong; Zhao, Hongyan; Xiao, Deli; Chuong, Pham-Huy; He, Jia; He, Hua
A novel mixed hemimicelles solid phase extraction based on magnetic graphene oxide (Fe3O4/GO) and ionic liquid (IL) was developed for the simultaneous extraction and determination of trace cephalosporins in spiked human urine. The high surface area and excellent adsorption capacity of the graphene oxide after modification with1-hexadecyl-3-methylmidazoliumbromide(C16mimBr) were utilized adequately in the solid phase extraction(SPE) process. A comprehensive study of the parameters affecting the extraction recovery, such as the zeta-potential of magnetic graphene oxide, amounts of magnetic graphene oxide and surfactant, pH of solution, ionic strength, extraction time, and desorption condition were optimized. A comparative study on the use of different surfacant-coated Fe3O4/GO NPs as sorbents was presented. Good linearity (R(2)>0.9987) for all calibration curves was obtained. The LODs were ranged between 0.6 and 1.9ng mL(-1) for the cephalosporins and the LOQs were 1.5 to 5.5, respectively. Satisfactory recoveries(84.3% to 101.7%)and low relative standard deviations from 1.7% to 6.3% in biological matrices were achieved. The mixed hemimicelles magnetic SPE (MSPE) method based on ILs and Fe3O4/GO NPs magnetic separation has ever been successfully used for pretreatment of complex biological samples. PMID:27266334
Wu, Lin; Hu, Yufang; Sha, Yuhong; Li, Wenrou; Yan, Tiantian; Wang, Sui; Li, Xing; Guo, Zhiyong; Zhou, Jun; Su, Xiurong
A novel "in-electrode"-type electrochemiluminescence (ECL) immunosensor for the sensitive detection of squamous cell carcinoma antigen (SCCA) was constructed using magnetic graphene oxide (nanoFe3O4@GO) and Au nanoparticles/graphitic-phase carbon nitride (AuNPs/g-C3N4). The capture probe was prepared by immobilizing the primary antibody of SCCA (Ab1) on the nanoFe3O4@GO, while the AuNPs/g-C3N4 nanocomposites labelled the secondary antibody of SCCA (Ab2), which acted as a signal tag. The recognition scaffold was the following: the capture probe was immobilized onto the magnetic electrode surface that caught the target SCCA and finally allowed the immobilization of the signal tag via the interaction between antigen and antibody. Importantly, a high ECL signal could be obtained due to the unique immunocomplex, which ensured all of the g-C3N4 on the outmost plane were directly fixed onto the electrode surface and became part of the electrode surface. This resulted in an enhanced efficiency of the g-C3N4 for electrochemical luminescence, thus extending the outer Helmholtz plane (OHP) of the proposed electrode and leading to high sensitivity. Taking advantage of both nanoFe3O4@GO and AuNPs/g-C3N4, the ECL intensity was found to increase logarithmically with SCCA concentration in a wide linear range from 0.001 to 10ng/mL and with a detection limit of 0.4pg/mL. The proposed "in-electrode"-type ECL immunosensor was used to analyse SCCA in human serum, and satisfactory recoveries were obtained, indicating that the proposed method was promising for practical applications in the clinical diagnosis of SCCA. PMID:27591611
Hasanzadeh, Mohammad; Shadjou, Nasrin
For the first time magnetic graphene oxide functionalized by chlorosulfonic acid Fe3O4-GO-SO3H was used for electrode modification and electrocatalytic oxidation of three selected parabens. Scanning electron microscopy (SEM) and X-ray diffraction techniques are utilized in order to study the surface morphology of the modified electrode. The modified electrode was applied for parabens detection using cyclic voltammetry (CV), chronoamperometry, and amperometry methods. The modified electrode shows many advantages as a parabens sensor such as simple preparation method without using any specific electron transfer mediator or specific reagent, excellent catalytic activity, short response time, long-term stability and remarkable antifouling property toward parabens.
Liu, Zhigang; Wang, Yi; Deng, Rong; Yang, Liyuan; Yu, Shihua; Xu, Shuping; Xu, Weiqing
A multifunctional magnetic graphene surface-enhanced Raman scattering (SERS) substrate was fabricated successfully by the layer-by-layer assembly of silver and graphene oxide (GO) nanoparticles (NPs) on the magnetic ferroferric oxide particles (Fe3O4@GO@Ag). This ternary particle possesses magnetic properties, SERS activity, and adsorption ability simultaneously. Owing to the multifunction of this Fe3O4@GO@Ag ternary complex, we put forward a new method called a surface magnetic solid-phase extraction (SMSPE) technique, for the SERS detections of pesticide residues on the fruit peels. SMSPE integrates many sample pretreatment procedures, such as surface extraction, separation sample, and detection, all-in-one. So this method shows great superiority in simplicity, rapidity, and high efficiency above other standard methods. The whole detection process can be finished within 20 min including the sample pretreatment and SERS detection. Owing to the high density of Ag NPs, the detection sensitivity is high enough that the lowest detectable concentrations are 0.48 and 40 ng/cm(2) for thiram and thiabendazole, which are much lower than the maximal residue limits in fruit prescribed by the U.S. Environmental Protection Agency. This multifunctional ternary particle and its corresponding analytical method have been proven to be applicable for practical samples and also valuable for other surface analysis. PMID:27191584
Soleymani, Jafar; Hasanzadeh, Mohammad; Shadjou, Nasrin; Khoubnasab Jafari, Maryam; Gharamaleki, Jalil Vaez; Yadollahi, Mehdi; Jouyban, Abolghasem
A novel magnetic nanocomposite was synthesized in one step using polymerization of magnetic graph oxide grafted with chlorosulfonic acid (Fe3O4-GO-SO3H) in the presence of polystyrene. The prepared magnetic nanocomposite was characterized using transmission electron microscopy (TEM), dynamic differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), (Thermo-gravimetric/differential thermal analysis (DTA)), Fourier transform infrared (FTIR), and UV-Vis techniques. Magnetic nanocomposite was casted on the surface of the glassy carbon electrode (PS/Fe3O4-GO-SO3H/GCE) and used for the detection and determination of doxorubicin hydrochloride (DOX) in human biological fluids. The cyclic voltammograms (CVs) of the modified electrode in aqueous solution displayed a pair of well-defined, stable and irreversible reductive/oxidation redox systems. CV study indicated that the oxidation process is irreversible and adsorption controlled. In addition, CV results indicated that DOX is oxidized via two electrons and three protons which is an unusual approach for the oxidation of DOX. A sensitive and time-saving procedure was developed for the analysis of DOX in plasma, cerebrospinal fluid, and urine with detection limit of 4.9 nM, 14 nM and 4.3 nM, respectively. PMID:26838892
Li, Zongle; He, Chunying; Wang, Zhao; Gao, Yachen; Dong, Yongli; Zhao, Cheng; Chen, Zhimin; Wu, Yiqun; Song, Weina
Tetracarboxylic Zn(ii) phthalocyanine-amino functionalized graphene oxide (ZnPcC4-NGO) hybrid materials have been prepared by a covalent functionalization method. The characterizations indicate that the amino-functionalization of GO has an important influence on the structure and photophysical properties of the ZnPcC4-NGO hybrid. The ZnPcC4-NGO hybrid exhibits enhanced photo-induced electron transfer or energy transfer (PET/ET), compared to the ZnPcC4 covalent functionalized GO (ZnPcC4-GO), owing to the presence of the extended sp(2) carbon configurations, along with the partial reduction of the NGO nanosheets and the introduction of electron-donating ethylenediamine. The nonlinear optical (NLO) properties of the hybrids were investigated using the Z-scan technique at 532 nm with 4 ns laser pulses. The results show that the efficient covalent functionalization and partial reduction of NGO cause the ZnPcC4-NGO hybrid to possess evidently larger NLO properties than the individual NGO, ZnPcC4 and the ZnPcC4-GO hybrid. The enhanced NLO performance can be attributed to the increased excited state absorption from the extended sp(2) carbon configurations of the NGO moiety, reverse saturable absorption arising from ZnPcC4 moiety, and the contribution of the efficient PET/ET process between the ZnPcC4 and NGO moieties in the hybrid. PMID:27296527
Chang, Qing; Jiang, Guo-Dong; Hu, Meng-Xuan; Huang, Jia; Tang, He-Qing
A simple ultrasound-assisted co-precipitation method was developed to prepare magnetic Fe3O4/graphene oxide (Fe3O4/ GO) nanoparticles. The characterization with transmission electron microscope (TEM) indicated that the products possessed small particle size. The hysteresis loop of the dried Fe3O4/GO nanoparticles demonstrated that the sample had typical features of superparamagnetic material. Batch adsorption studies were carried out to investigate the effects of the initial pH of the solution, the dosage of adsorbent, the contact time and temperature on the adsorption of methylene blue. The results indicated that the composites prepared could be used over a broad pH range (pH 6-9). The adsorption process was very fast within the first 25 min and the equilibrium was reached at 180 min. The adsorption equilibrium and kinetics data fitted well with the Langmuir isotherm model and the pseudo-second-order kinetic model. The adsorption process was a spontaneous and endothermic process in nature. The composite exhibited fairly high adsorption capacity (196.5 mg.g-1) of methylene blue at 313 K. In addition, the magnetic composite could be effectively and simply separated by using an external magnetic field, and then regenerated by hydrogen peroxide and recycled for further use. The results indicated that the adsorbent had a potential in the application of the dye wastewater treatment.
Xia, Binyuan; Chu, Mingfu; Wang, Shaofei; Wang, Wanqing; Yang, Shanli; Liu, Chengbin; Luo, Shenglian
Here for the first time, we present a novel electrochemiluminescence (ECL) sensor based on graphitic carbon nitride/graphene oxide (g-C3N4/GO) hybrid for the ultrasensitive detection of Cu(2+), which is a common pollutant in environmental system. The g-C3N4/GO shows stable ECL signal in the presence of the self-produced coreactant from oxygen reduction, and the ECL signal could be effectively quenched by Cu(2+), the possible ECL detection mechanism has been proposed in detail. GO can not only significantly enhance the cathodic ECL signal of g-C3N4 (∼3.8 times), but also serve as immobilization platform for g-C3N4. After optimization of experimental conditions, the proposed protocol can offer an ultrasensitive, highly selective and recyclable method for the detection of Cu(2+) with a low detection limit of 1.0 × 10(-11) M and a wide linear range from 1.0 × 10(-11) to 1.0 × 10(-7) M. Moreover, the practicability of the ECL sensor in real wastewater samples is also tested, showing that the proposed ECL sensor could be a promising alternative method for the emergency and routine monitoring of Cu(2+) in real sample. PMID:26388369
Xia, Binyuan; Chu, Mingfu; Wang, Shaofei; Wang, Wanqing; Yang, Shanli; Liu, Chengbin; Luo, Shenglian
Here for the first time, we present a novel electrochemiluminescence (ECL) sensor based on graphitic carbon nitride/graphene oxide (g-C3N4/GO) hybrid for the ultrasensitive detection of Cu(2+), which is a common pollutant in environmental system. The g-C3N4/GO shows stable ECL signal in the presence of the self-produced coreactant from oxygen reduction, and the ECL signal could be effectively quenched by Cu(2+), the possible ECL detection mechanism has been proposed in detail. GO can not only significantly enhance the cathodic ECL signal of g-C3N4 (∼3.8 times), but also serve as immobilization platform for g-C3N4. After optimization of experimental conditions, the proposed protocol can offer an ultrasensitive, highly selective and recyclable method for the detection of Cu(2+) with a low detection limit of 1.0 × 10(-11) M and a wide linear range from 1.0 × 10(-11) to 1.0 × 10(-7) M. Moreover, the practicability of the ECL sensor in real wastewater samples is also tested, showing that the proposed ECL sensor could be a promising alternative method for the emergency and routine monitoring of Cu(2+) in real sample.
Chen, Xiao-juan; Dai, You-zhi; Wang, Xing-yan; Guo, Jing; Liu, Tan-hua; Li, Fen-fang
A series of visible-light responsive photocatalysts prepared using Ag3PO4 immobilized with graphene oxide (GO) with varying GO content were obtained by an electrostatically driven method, and 2,4-dichlorophenol (2,4-DCP) was used to evaluate the performance of the photocatalysts. The composites exhibited superior photocatalytic activity and stability compared with pure Ag3PO4. When the content of GO was 5%, the degradation efficiency of 2,4-DCP could reach 98.95%, and 55.91% of the total organic (TOC) content was removed within 60 min irradiation. Meanwhile, the efficiency of 91.77% was achieved for 2,4-DCP degradation even after four times of recycling in the photocatalysis/Ag3PO4-GO (5%) system. Reactive species of O2(˙-), OH˙ and h(+) were considered as the main participants for oxidizing 2,4-DCP, as confirmed by the free radical capture experiments. And some organic intermediates including 4-chlorophenol (4-CP), hydroquinone (HQ), benzoquinone (BZQ), 2-chlorohydroquinone and hydroxyhydroquinone (HHQ) were detected by comparison with the standard retention times from the high performance liquid chromatography (HPLC). In short, the enhanced photocatalytic property of Ag3PO4-GO was closely related to the strong absorption ability of GO relative to 2,4-DCP, the effective separation of photogenerated electron-hole pairs, and the excellent electron capture capability of GO.
Yao, Chengli; Xie, Anjian; Shen, Yuhua; Zhu, Jinmiao; Li, Hongying
Nacre-like calcium carbonate nanostructures have been mediated by an ionic liquid (IL)-graphene oxide (GO) composite template. The resultant crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffractometry (XRD). The results showed that either 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) or graphene oxide can act as a soft template for calcium carbonate formation with unusual morphologies. Based on the time-dependent morphology changes of calcium carbonate particles, it is concluded that nacre-like calcium carbonate nanostructures can be formed gradually utilizing [BMIM]BF4/GO composite template. During the process of calcium carbonate formation, [BMIM]BF4 acted not only as solvents but also as morphology templates for the fabrication of calcium carbonate materials with nacre-like morphology. Based on the observations, the possible mechanisms were also discussed.
Mishra, Amodini; Mohanty, Tanuja
Nanocomposite of magnetite/graphene oxide (Fe3O4/GO) has been synthesized by co-precipitation method. The phase formation of the magnetite nanoparticles (Fe3O4 NPs) was confirmed by X-ray diffraction (XRD) analysis. Effect of Fe3O4 NPs on the Raman spectra and on the surface potential of GO has been analyzed. Due to incorporation of NPs, change in the characteristic Raman peaks and also on the surface potential of GO is observed. Transmission electron microscopic (TEM) study has been carried out for surface morphology. Magnetic property measurement was carried out by using physical property measurement system (PPMS) at two different temperatures (30 K and 300K).
Omidinia, Eskandar; Shadjou, Nasrin; Hasanzadeh, Mohammad
Fe3O4-graphene oxide (GO) modified glassy carbon (GC) electrode was used as a new magnetic nanosensor for determination of phenylalanine (Phe). It was found that Fe3O4-GO has been stably absorbed on GC electrode modified by simple technique. The cyclic voltammograms of the modified electrode in an aqueous solution displayed a pair of well-defined, stable and irreversible reductive/oxidation redox systems. The apparent electron transfer rate constant (k(s)) and transfer coefficient (α) were determined by cyclic voltammetry and were approximately 9.3 s(-1) and 0.67, respectively. The modified electrode showed excellent catalytic activity towards the oxidation of Phe at an unusually positive potential in buffer solution. This nanosensor also displayed fast response time, high sensitivity, low detection limit and had a remarkably positive potential oxidation of Phe that decreased the effect of interferences in analysis.
Yao, Chengli; Xie, Anjian; Shen, Yuhua; Zhu, Jinmiao; Li, Hongying
Nacre-like calcium carbonate nanostructures have been mediated by an ionic liquid (IL)-graphene oxide (GO) composite template. The resultant crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffractometry (XRD). The results showed that either 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) or graphene oxide can act as a soft template for calcium carbonate formation with unusual morphologies. Based on the time-dependent morphology changes of calcium carbonate particles, it is concluded that nacre-like calcium carbonate nanostructures can be formed gradually utilizing [BMIM]BF4/GO composite template. During the process of calcium carbonate formation, [BMIM]BF4 acted not only as solvents but also as morphology templates for the fabrication of calcium carbonate materials with nacre-like morphology. Based on the observations, the possible mechanisms were also discussed. PMID:25842135
Costigliola, Lorenzo; Schrøder, Thomas B.; Dyre, Jeppe C.
The recent theoretical prediction by Maimbourg and Kurchan [e-print arXiv:1603.05023 (2016)] that for regular pair-potential systems the virial potential-energy correlation coefficient increases towards unity as the dimension d goes to infinity is investigated for the standard 12-6 Lennard-Jones fluid. This is done by computer simulations for d = 2, 3, 4 going from the critical point along the critical isotherm/isochore to higher density/temperature. In both cases the virial potential-energy correlation coefficient increases significantly. For a given density and temperature relative to the critical point, with increasing number of dimension the Lennard-Jones system conforms better to the hidden-scale-invariance property characterized by high virial potential-energy correlations (a property that leads to the existence of isomorphs in the thermodynamic phase diagram, implying that it becomes effectively one-dimensional in regard to structure and dynamics). The present paper also gives the first numerical demonstration of isomorph invariance of structure and dynamics in four dimensions. Our findings emphasize the need for a universally applicable 1/d expansion in liquid-state theory; we conjecture that the systems known to obey hidden scale invariance in three dimensions are those for which the yet-to-be-developed 1/d expansion converges rapidly.
Costigliola, Lorenzo; Schrøder, Thomas B; Dyre, Jeppe C
The recent theoretical prediction by Maimbourg and Kurchan [e-print arXiv:1603.05023 (2016)] that for regular pair-potential systems the virial potential-energy correlation coefficient increases towards unity as the dimension d goes to infinity is investigated for the standard 12-6 Lennard-Jones fluid. This is done by computer simulations for d = 2, 3, 4 going from the critical point along the critical isotherm/isochore to higher density/temperature. In both cases the virial potential-energy correlation coefficient increases significantly. For a given density and temperature relative to the critical point, with increasing number of dimension the Lennard-Jones system conforms better to the hidden-scale-invariance property characterized by high virial potential-energy correlations (a property that leads to the existence of isomorphs in the thermodynamic phase diagram, implying that it becomes effectively one-dimensional in regard to structure and dynamics). The present paper also gives the first numerical demonstration of isomorph invariance of structure and dynamics in four dimensions. Our findings emphasize the need for a universally applicable 1/d expansion in liquid-state theory; we conjecture that the systems known to obey hidden scale invariance in three dimensions are those for which the yet-to-be-developed 1/d expansion converges rapidly. PMID:27334147
Liu, Yahua; Wang, Jingtao; Zhang, Haoqin; Ma, Chuanming; Liu, Jindun; Cao, Shaokui; Zhang, Xiang
In this study, sulfonated graphene oxide (SGO) nanosheets with controllable sulfonic acid group loading are synthesized via the facile distillation-precipitation polymerization, and then incorporated into chitosan (CS) matrix to prepare nanohybrid membranes. The microstructure and physicochemical properties of the resulting membranes are extensively investigated. Compared with CS control and GO-filled membranes, SGO-filled membranes attain enhanced thermal and mechanical stabilities due to the strong electrostatic attractions between -SO3H of SGO and -NH2 of CS, which inhibit the mobility of CS chains. Additionally, the inhibited mobility reduces the area swellings of SGO-filled membranes, reinforcing their structural stabilities. The incorporation of SGO generates acid-base pairs along CS-SGO interface, which work as facile proton-hoping sites and thus construct continuous and wide proton transfer pathways, yielding enhanced proton conductivities under both hydrated and anhydrous conditions. Meanwhile, the conductivity can be elevated by increasing the sulfonic acid group loading and content of SGO. Particularly, incorporating 2.0% S4GO can afford the nanohybrid membrane a 122.5% increase in hydrated conductivity and a 90.7% increase in anhydrous conductivity when compared with CS control membrane. The superior conduction properties then offered a significant enhancement in H2/O2 cell performances to the nanohybrid membranes, guaranteeing them to be promising proton exchange membranes.
Deng, Xiaodong; Liu, Xiaonan; Duan, Tao; Zhu, Wenkun; Yi, Zao; Yao, Weitang
Bayberry tannin (BT)-reduced graphene oxide (rGO) sponges have been prepared by self-assembly, with bayberry tannin serving as both reductant and surface functionalization agent. The synthetic method is based on the self-assembly of graphene oxide (GO) sheets into porous hydrogel structures. By varying the weight ratio of GO to BT, a series of sorbents with different densities of organic molecules have been obtained and applied to remove Sr2+ from aqueous solutions. Adsorption isotherms (Langmuir and Freundlich) and kinetics (pseudo-first order and pseudo-second order) have been investigated to discuss the sorption performance of rGO/BT sponges. The rGO/BT (w/w 1:1) sponge shows excellent adsorption properties for Sr2+, with maximum capacities of 67.98 mg g-1. The adsorption capacity is much higher than those in classic Sr2+ adsorbents, such as hydrous manganese dioxide, Egyptian soils, Hydroxyapatite nanoparticles, sodium hexa-titanate nanofibers, Graphene oxide, artificially altered phlogopite(Ca-Phl), and PB/Fe3O4/GO. Adsorption mechanisms have been examined using the x-ray photoelectron spectra of sorbents before and after Sr2+ adsorption, and the results indicate that the sorption of Sr2+ on GO and GO/BT 1.0 is largely depended on oxygen functional groups. The results show that the GO/BT sponge is a promising candidate for adsorbing Sr2+ ion.
Deng, Xiaodong; Liu, Xiaonan; Duan, Tao; Zhu, Wenkun; Yi, Zao; Yao, Weitang
Bayberry tannin (BT)–reduced graphene oxide (rGO) sponges have been prepared by self–assembly, with bayberry tannin serving as both reductant and surface functionalization agent. The synthetic method is based on the self-assembly of graphene oxide (GO) sheets into porous hydrogel structures. By varying the weight ratio of GO to BT, a series of sorbents with different densities of organic molecules have been obtained and applied to remove Sr2+ from aqueous solutions. Adsorption isotherms (Langmuir and Freundlich) and kinetics (pseudo-first order and pseudo-second order) have been investigated to discuss the sorption performance of rGO/BT sponges. The rGO/BT (w/w 1:1) sponge shows excellent adsorption properties for Sr2+, with maximum capacities of 67.98 mg g‑1. The adsorption capacity is much higher than those in classic Sr2+ adsorbents, such as hydrous manganese dioxide, Egyptian soils, Hydroxyapatite nanoparticles, sodium hexa-titanate nanofibers, Graphene oxide, artificially altered phlogopite(Ca–Phl), and PB/Fe3O4/GO. Adsorption mechanisms have been examined using the x-ray photoelectron spectra of sorbents before and after Sr2+ adsorption, and the results indicate that the sorption of Sr2+ on GO and GO/BT 1.0 is largely depended on oxygen functional groups. The results show that the GO/BT sponge is a promising candidate for adsorbing Sr2+ ion.
Patzel, Brenda; McBride, Maryellen; Bunting, Judith; Anno, Tony
Whether a service member is active duty or part of the National Guard, deployment of these service members is a major issue for most families. There is limited knowledge of the experience of multiple deployments on the family. The purpose of this study was to describe experiences of wives of National Guard soldiers that were deployed more than once. Nine wives were interviewed. An analysis of the interviews revealed four themes: (1) "Life Goes On" (i.e., despite the repeated deployments, life continues at home); (2) the "Guard is a Different Animal" (i.e., life as a National Guard spouse is different from that of an active duty spouse); (3) "It's a Mind-Set" (i.e., how wives cope their husband's deployment); and (4) "Going Back Again" (i.e., wives' experiences of multiple deployments). Exploring how multiple deployments affects wives of National Guard soldiers is helpful in understanding their experiences and the adjustments that must be made in family life. Knowledge of the experiences of these wives may help in formulating more effective interventions with families who have experienced multiple deployments.
Azizian, Mohammad F.; Behrens, Sebastian; Sabalowsky, Andrew; Dolan, Mark E.; Spormann, Alfred M.; Semprini, Lewis
A continuous-flow anaerobic column experiment was conducted to evaluate the reductive dechlorination of tetrachloroethene (PCE) in Hanford aquifer material after bioaugmentation with the Evanite (EV) culture. An influent PCE concentration of 0.09 mM was transformed to vinyl chloride (VC) and ethene (ETH) within a hydraulic residence time of 1.3 days. The experimental breakthrough curves were described by the one-dimensional two-site-nonequilibrium transport model. PCE dechlorination was observed after bioaugmentation and after the lactate concentration was increased from 0.35 to 0.67 mM. At the onset of reductive dehalogenation, cis-dichloroethene (c-DCE) concentrations in the column effluent exceeded the influent PCE concentration indicating enhanced PCE desorption and transformation. When the lactate concentration was increased to 1.34 mM, c-DCE reduction to vinyl chloride (VC) and ethene (ETH) occurred. Spatial rates of PCE and VC transformation were determined in batch-incubated microcosms constructed with aquifer samples obtained from the column. PCE transformation rates were highest in the first 5 cm from the column inlet and decreased towards the column effluent. Dehalococcoides cell numbers dropped from ˜ 73.5% of the total Bacterial population in the original inocula, to about 0.5% to 4% throughout the column. The results were consistent with estimates of electron donor utilization, with 4% going towards dehalogenation reactions.
Liu, Shaobo; Wang, Hui; Chai, Liyuan; Li, Meifang
The Fe3O4/graphene oxide-supported 1,2-diaminocyclohexanetetraacetic acid composite (Fe3O4/GO/DCTA) was used as an adsorbent for Cu(II) removal. The effects of six organic acid ligands (formate, acetate, benzoate, oxalate, tartrate, and edetate) on the adsorption process were investigated in single- and multi-ligand systems. The results demonstrated that the adsorption processes were affected by solution pH and ionic strength. The experimental data of kinetics and isotherm followed the pseudo-second-order model and the Langmuir model, respectively. In the single-ligand systems, the presence of formate, acetate, and benzoate slightly altered the Cu(II) adsorption property, while the adsorption processes were significantly affected by the oxalate, tartrate, and edetate ligands. In the multi-ligand systems, the Cu(II) adsorption was influenced by the type and concentration of organic acid ligands. The sequence of the main effect was found to be: edetate>oxalate>benzoate>formate>tartrate>acetate, and the sequence of the two-factor interaction effect was found to be: AE (formate×tartrate)>BF (acetate×edetate)>AF (formate×edetate)>BD (acetate×oxalate)>AC (formate×benzoate)>AD (formate×oxalate)>AB (formate×acetate). PMID:27309949
Deng, Lin; Li, Qiujin; Al-Rehili, Safa'a; Omar, Haneen; Almalik, Abdulaziz; Alshamsan, Aws; Zhang, Jianfei; Khashab, Niveen M
Premature drug release is a common drawback in stimuli-responsive drug delivery systems (DDS), especially if it depends on internal triggers, which are hard to control, or a single external stimulus, which can only have one function. Thus, many DDS systems have been reported that combined different triggers; however, limited success has been established in fine-tuning the release process, mainly due to the poor bioavailability and complexity of the reported designs. This paper reports the design of a hybrid microcapsule (h-MC) by a simple layer-by-layer technique comprising polysaccharides (sodium alginate, chitosan, and hyaluronic acid), iron oxide, and graphene oxide (GO). Electrostatic assembly of the oppositely charged polysaccharides and graphene sheets provided a robust structure in which to load drugs through pH control. The polysaccharide component ensured high biocompatibility, bioavailability, and tumor cells targeting. The alternative magnetic field and near-infrared laser triggerable Fe3O4@GO component provided for dual high-energy and high-penetration hyperthermia therapy. On-demand drug release from h-MC can be achieved by synchronizing these external triggers, making the release highly controllable. The synergistic effect of hyperthermia and chemotherapy was successfully confirmed in vitro and in vivo. PMID:26915062
Marek, Ana; Kaján, Győző L; Kosiol, Carolin; Harrach, Balázs; Schlötterer, Christian; Hess, Michael
Complete genomes of the first isolates of pigeon adenovirus 1 (PiAdV-1) and Muscovy duck adenovirus (duck adenovirus 2, DAdV-2) were sequenced. The PiAdV-1 genome is 45,480bp long, and has a gene organization most similar to turkey adenovirus 1. Near the left end of the genome, it lacks ORF0, ORF1A, ORF1B and ORF1C, and possesses ORF52, whereas six novel genes were found near the right end. The DAdV-2 genome is 43,734bp long, and has a gene organization similar to that of goose adenovirus 4 (GoAdV-4). It lacks ORF51, ORF1C and ORF54, and possesses ORF55A and five other novel genes. PiAdV-1 and DAdV-2 genomes contain two and one fiber genes, respectively. Genome organization, G+C content, molecular phylogeny and host type confirm the need to establish two novel species (Pigeon aviadenovirus A and Duck aviadenovirus B) within the genus Aviadenovirus. Phylogenetic data show that DAdV-2 is most closely related to GoAdV-4.
Facile and tunable fabrication of Fe3O4/graphene oxide nanocomposites and their application in the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from environmental water samples.
Han, Qiang; Wang, Zonghua; Xia, Jianfei; Chen, Sha; Zhang, Xiaoqiong; Ding, Mingyu
An electrostatic self-assembly approach was employed to prepare Fe(3)O(4)/graphene oxide nanocomposites, and their application in the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from environmental samples was investigated. With the highly hydrophilic graphene oxide sheets and positively charged surface of the Fe(3)O(4) nanoparticles, the nanocomposites were synthesized through electrostatic interaction in aqueous solution. Simultaneously, the different loading amounts of Fe(3)O(4) onto the graphene oxide were easily controlled by changing the proportion of the initial precursors. The identity of the hybrid materials was confirmed using transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and a vibrating sample magnetometer. Five polycyclic aromatic hydrocarbons were selected as model analytes to validate the extraction performance of the Fe(3)O(4)/GO nanocomposite as a MSPE sorbent. The excellent adsorption property was attributed to the dominant roles of π-π stacking interaction and hydrophobic interaction. After optimizing the conditions, the results indicated that the recoveries of these compounds were in the range of 76.8-103.2%, with relative standard deviations ranging between 1.7% and 11.7%; the limits of detection were in the range of 0.09-0.19 ng mL(-1).
Xu, Yanjie; Wang, Lincai; Cao, Peiqi; Cai, Chuanlin; Fu, Yanbao; Ma, Xiaohua
A simple co-precipitation method utilizing SDS (sodium dodecyl sulfate) as template and ammonia as precipitant is successfully employed to synthesize nickel cobalt oxide/graphene oxide (NiCo2O4/GO) composite. The as-prepared composite (NCG-10) exhibits a high capacitance of 1211.25 F g-1, 687 F g-1 at the current density of 1 A g-1, 10 A g-1 and good cycling ability which renders NCG-10 as promising electrode material for supercapacitors. An asymmetric supercapacitor (ASC) (full button cell) has been constructed with NCG-10 as positive electrode and lab-made reduced graphene oxide (rGO) as negative electrode. The fabricated NCG-10//rGO with an extended stable operational voltage of 1.6 V can deliver a high specific capacitance of 144.45 F g-1 at a current density of 1 A g-1. The as-prepared NCG-10//rGO demonstrates remarkable energy density (51.36 W h kg-1 at 1 A g-1), high power density (50 kW kg-1 at 20 A g-1). The retention of capacitance is 88.6% at the current density of 8 A g-1 after 2000 cycles. The enhanced capacitive performance can be attributed to the improved specific surface area and 3D open area of NCG-10 generated by the pores and channels with the substantial function of SDS.
Bybi, A; Grondel, S; Assaad, J; Hladky-Hennion, A-C
This paper describes a procedure to extend the crosstalk correction method presented in a previous paper [A. Bybi, S. Grondel, J. Assaad, A.-C. Hladky-Hennion, M. Rguiti, Reducing crosstalk in array structures by controlling the excitation voltage of individual elements: a feasibility study, Ultrasonics, 53 (6) (2013) 1135-1140] from the harmonic regime to the transient one. For this purpose a part of an ultrasonic transducer array radiating in water is modeled around the frequency 0.5 MHz using the finite element method. The study is carried out at low frequency in order to respect the same operating conditions than the previous paper. This choice facilitated the fabrication of the transducer arrays and the comparison of the numerical results with the experimental ones. The modeled array is composed of seventeen elements with the central element excited, while the others are grounded. The matching layers and the backing are not taken into account which limits the crosstalk only to the piezoelectric elements and fluid. This consideration reduces the structure density mesh and results in faster computation time (about 25 min for each configuration using a computer with a processor Intel Core i5-3210M, frequency 2.5 GHz and having 4 Go memory (RAM)). The novelty of this research work is to prove the efficiency of the crosstalk correction method in large frequency band as it is the case in medical imaging. The numerical results show the validity of the approach and demonstrate that crosstalk can be reduced by at least 13 dB in terms of displacement. Consequently, the directivity pattern of the individual element can be improved. PMID:24064509
Asgharinezhad, Ali Akbar; Ebrahimzadeh, Homeira
The simultaneous extraction of acidic, basic and amphiprotic pollutants from various samples is a considerable and disputable concept in sample preparation strategies. In this study, for the first time, coextraction of acidic, basic and amphiprotic pollutants (polar and apolar) with multiwalled carbon nanotubes/Fe3O4@polypyrrole (MWCNTs/Fe3O4@PPy) composite based dispersive micro-solid phase extraction followed by high performance liquid chromatography-photo diode array detection was introduced. Firstly, the extraction efficiency of various magnetic nanosorbents including Fe3O4, MWCNTs/Fe3O4, graphene oxide/Fe3O4 (GO/Fe3O4), Fe3O4@PPy, MWCNTs/Fe3O4@PPy and GO/Fe3O4@PPy were compared. The results revealed that MWCNTs/Fe3O4@PPy nanocomposite has higher extraction efficiency for five selected model analytes (4-nitrophenol, 3-nitroaniline, 2,4-dichloroaniline, 3,4-dichloroaniline and 1-amino-2-naphthol). Box-Behnken design methodology combined with desirability function approach was applied to find out the optimal experimental conditions. The opted conditions were: pH of the sample, 8.2; sorbent amount, 12 mg; sorption time, 5.5 min; salt concentration, 14% w/w; type and volume of the eluent, 120 μL acetonitrile; elution time; 2 min. Under the optimum conditions detection limits and linear dynamic ranges were achieved in the range of 0.1-0.25 μg L(-1) and 0.5-600 μg L(-1), respectively. The percent of extraction recovery and relative standard deviations (n=5) were in the range of 45.6-82.2 and 4.0-8.5, respectively. Ultimately, the applicability of this method was successfully confirmed by analyzing rain, snow and river water samples and satisfactory results were obtained.
Nakamura, Takashi; Takeda, Tomoya; Tokuji, Yoshihiko
The common water-soluble organic germanium compound poly-trans-[(2-carboxyethyl) germasesquioxane] (Ge-132) exhibits activities related to immune responses and antioxidant induction. In this study, we evaluated the antioxidative effect of dietary Ge-132 in the plasma of mice. Male ICR mice (seven mice per group) received an AIN-76 diet with 0.05% Ge-132; three groups received the Ge-132-containing diet for 0, 1 or 4 days. The plasma alpha-tocopherol (α-tocopherol) concentration increased from 6.85 to 9.60 μg/ml after 4 days of Ge-132 intake (p<0.05). We evaluated the changes in hepatic gene expression related to antioxidative activity as well as in the entire expression profile after one day of Ge-132 intake, using DNA microarray technology. We identified 1,220 genes with altered expression levels greater than 1.5-fold (increased or decreased) as a result of Ge-132 intake, and α-tocopherol transfer protein (Ttpa) gene expression was increased 1.62-fold. Immune activation was identified as the category with the most changes (containing 60 Gene Ontology (GO) term biological processes (BPs), 41 genes) via functional clustering analysis of altered gene expression. Ge-132 affected genes in clusters related to ATP production (22 GO term BPs, 21 genes), lipid metabolism (4 GO term BPs, 38 genes) and apoptosis (5 GO term BPs). Many GO term BPs containing these categories were significantly affected by the Ge-132 intake. Oral Ge-132 intake may therefore have increased plasma α-tocopherol levels by up-regulating α-tocopherol transfer protein (Ttpa) gene expression.
Fu, Yongsheng; Zhu, Junwu; Hu, Chong; Wu, Xiaodong; Wang, Xin
An in situ chemical synthetic approach has been designed for the fabrication of a covalently coupled hybrid consisting of graphitic carbon nitride (g-C3N4) with reduced graphene oxide (rGO) with differing g-C3N4/rGO ratio. The epoxy groups of graphene oxide (GO) undergo a nucleophilic substitution reaction with dicyandiamide (C2H4N4) to form the C2H4N4-GO composite via a covalent C-N bond, and then both the in situ polymerization of C2H4N4 and the thermal reduction of GO can be achieved at higher temperatures, forming the covalently coupled g-C3N4-rGO. FT-IR, CP-MAS NMR and XPS analyses, clearly revealed a covalent interaction between the g-C3N4 and rGO sheets. The g-C3N4-rGO exhibits an unprecedented high, stable and reversible capacity of 1525 mA h g(-1) at a current density of 100 mA g(-1) after 50 cycles. Even at a large current density of 1000 mA g(-1), a reversible capacity of 943 mA h g(-1) can still be retained. The superior electrochemical performance of g-C3N4-rGO is attributed to the specific characteristics of the unique nanostructure of g-C3N4-rGO and the concerted effects of g-C3N4 and rGO, including covalent interactions between the two moieties, the good conductivity and high special surface area of the nanocomposite, as well as the template effect of the planar amino group of g-C3N4 for the dispersed decoration of Li(+) ions.
McDonald, Catherine C; Curry, Allison E; Kandadai, Venk; Sommers, Marilyn S; Winston, Flaura K
Motor vehicle crashes are the leading cause of death and acquired disability during the first four decades of life. While teen drivers have the highest crash risk, few studies examine the similarities and differences in teen and adult driver crashes. We aimed to: (1) identify and compare the most frequent crash scenarios-integrated information on a vehicle's movement prior to crash, immediate pre-crash event, and crash configuration-for teen and adult drivers involved in serious crashes, and (2) for the most frequent scenarios, explore whether the distribution of driver critical errors differed for teens and adult drivers. We analyzed data from the National Motor Vehicle Crash Causation Survey, a nationally representative study of serious crashes conducted by the U.S. National Highway Traffic Safety Administration from 2005 to 2007. Our sample included 642 16- to 19-year-old and 1167 35- to 54-year-old crash-involved drivers (weighted n=296,482 and 439,356, respectively) who made a critical error that led to their crash's critical pre-crash event (i.e., event that made the crash inevitable). We estimated prevalence ratios (PR) and 95% confidence intervals (CI) to compare the relative frequency of crash scenarios and driver critical errors. The top five crash scenarios among teen drivers, accounting for 37.3% of their crashes, included: (1) going straight, other vehicle stopped, rear end; (2) stopped in traffic lane, turning left at intersection, turn into path of other vehicle; (3) negotiating curve, off right edge of road, right roadside departure; (4) going straight, off right edge of road, right roadside departure; and (5) stopped in lane, turning left at intersection, turn across path of other vehicle. The top five crash scenarios among adult drivers, accounting for 33.9% of their crashes, included the same scenarios as the teen drivers with the exception of scenario (3) and the addition of going straight, crossing over an intersection, and continuing on a
Mao, Yuqing; Van Auken, Kimberly; Li, Donghui; Arighi, Cecilia N.; McQuilton, Peter; Hayman, G. Thomas; Tweedie, Susan; Schaeffer, Mary L.; Laulederkind, Stanley J. F.; Wang, Shur-Jen; Gobeill, Julien; Ruch, Patrick; Luu, Anh Tuan; Kim, Jung-jae; Chiang, Jung-Hsien; Chen, Yu-De; Yang, Chia-Jung; Liu, Hongfang; Zhu, Dongqing; Li, Yanpeng; Yu, Hong; Emadzadeh, Ehsan; Gonzalez, Graciela; Chen, Jian-Ming; Dai, Hong-Jie; Lu, Zhiyong
annotation. Database URL: http://www.biocreative.org/tasks/biocreative-iv/track-4-GO/. PMID:25157073