GC Surface Research Articles

3D Hollow Quasi-Graphite Capsules/Polyaniline Hybrid with a High Performance for Room-Temperature Ammonia Gas Sensors.

Designing sensing materials with novel morphologies and compositions is eminently challenging to achieve high-performance gas sensor devices. Herein, an in situ oxidative polymerization approach is developed to construct three-dimensional (3D) hollow quasi-graphite capsules/polyaniline (GCs/PANI) hierarchical hybrids by decorating protonated PANI on the surface of GCs; as a result, an immensely active and sensitive material was developed for sensing ammonia gas at room temperature. Moreover, the GCs possessed a capsule-like hollow/open structure with partially graphitized walls, and PANI nanospheres were uniformly decorated on the GC surfaces. Furthermore, the inflexible and rigid 3D ordered chemistry of these materials provides the resulting hybrids with a large interfacial surface area, which not only allows for rapid adsorption and charge transfer but also provides the necessary structural stability. The 3D hollow GCs/PANI hybrids exhibit excellent performance; the GCs/PANI-3 hybrid is highly sensitive (with a response value of 1.30) toward 10 ppm NH3 gas and has short response and recovery times of 34 and 42 s, respectively. The GCs/PANI-3 hybrid also demonstrates a good selectivity, repeatability, and long-term stability, which are attributed to the substantial synergistic effect of the GCs and PANI. The design of such a unique 3D ordered framework provides a promising pathway to achieve room-temperature gas sensors for commercial applications.

ANALYSIS OF INTERMOLECULAR INTERACTIONS IN MIXED ADSORPTION LAYERS OF SURFACTANTS

The adsorption of the surfactants mixtures of different chemical nature such as Triton X-100 and sodium hexadecyl sulfate at the surface of graphitized carbon black was studied. Using the model of phase separation (the Rubi–Rosen approach), the composition of the mixed adsorption layers and parameters of interaction between the surfactant molecules in the adsorption layers were calculated. It was found that mixed adsorption layers are enriched with molecules of the non-ionic surfactant Triton X-100.
 The purpose of the work was to study the adsorption of binary mixtures of surfactants of various chemical nature on the surface of non-porous hydrophobic carbon sorbent at different SAS ratio in mixtures.
 The results of calculations show that the composition of the adsorption layer on the surface of the GC is significantly different from the ratio of surfactants in the solution. The value of the parameter χ indicates that the mixed adsorption layer on the surface of the GC is enriched with non-ionic surfactant molecules, even with a small its content in the solution (αTХ-100 = 0,2). With an increase in the ТХ-100 molar fraction in the binary solution from 0,2 to 0,8 its share in the adsorption layer increases in approximately 1.5 times. Negative values of the interaction parameters βs indicate excessive attraction of the molecules and ions of the mixture components in the mixed adsorption layers. An increase in the absolute value of the parameter βs with an increase in αTХ-100 in the solution characterizes the enhancement of the interactions between the components in the adsorption layer.
 Thus, in the course of experiments carried out for mixed systems of SHDS-ТХ-100, the existence of a synergistic effect in relation to an increase in the adsorption of surfactants on the GC surface was established. It is found that mixed adsorption layers are enriched with molecules of the non-ionic surface active substance of the triton X-100.

Synthesis of gold nanoparticles on diazonium-generated heteroaryl films and their electrocatalytic activities

In this paper, a novel electrochemical sensing platform has been developed based on the electrodes modified with heteroaromatic molecules decorated with gold nanoparticles (AuNPs). For this purpose, the GC electrodes were first covered with pyridine and phenanthroline rings by using diazonium reduction method. Then, the formation of AuNPs was achieved via the electrochemical reduction of AuCl4− ions preadsorbed to the modified GC surfaces. The AuNPs, for comparison, were also prepared on polyphenylene films (PPh) obtained by electrochemical reduction of in situ generated benzenediazonium salts. The existence of the nanoparticles was confirmed by using spectroscopic and electrochemical techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and cyclic voltammetry. The results have shown that the homogeneity of particle distribution is strongly dependent on the nature of the organic film. The electrocatalytic capabilities of the resulting composite films were also assessed both in the anodic and cathodic regions for hydrazine hydrate oxidation and nitrobenzene reduction, respectively. It was found that the AuNPs-modified electrodes showed a significant catalytic effect, since metal nanosites on the surfaces offer a good electrical conductivity and large effective surface area.

Neisseria gonorrhoeae employs two protein inhibitors to evade killing by human lysozyme.

The bacterial pathogen Neisseria gonorrhoeae (Gc) infects mucosal sites rich in antimicrobial proteins, including the bacterial cell wall-degrading enzyme lysozyme. Certain Gram-negative bacteria produce protein inhibitors that bind to and inhibit lysozyme. Here, we identify Ng_1063 as a new inhibitor of lysozyme in Gc, and we define its functions in light of a second, recently identified lysozyme inhibitor, Ng_1981. In silico analyses indicated that Ng_1063 bears sequence and structural homology to MliC-type inhibitors of lysozyme. Recombinant Ng_1063 inhibited lysozyme-mediated killing of a susceptible mutant of Gc and the lysozyme-sensitive bacterium Micrococcus luteus. This inhibitory activity was dependent on serine 83 and lysine 103 of Ng_1063, which are predicted to interact with lysozyme’s active site residues. Lysozyme co-immunoprecipitated with Ng_1063 and Ng_1981 from intact Gc. Ng_1063 and Ng_1981 protein levels were also increased in Gc exposed to lysozyme. Gc lacking both ng1063 and ng1981 was significantly more sensitive to killing by lysozyme than wild-type or single mutant bacteria. When exposed to human tears or saliva, in which lysozyme is abundant, survival of Δ1981Δ1063 Gc was significantly reduced compared to wild-type, and survival was restored upon addition of recombinant Ng_1981. Δ1981Δ1063 mutant Gc survival was additionally reduced in the presence of human neutrophils, which produce lysozyme. We found that while Ng_1063 was exposed on the surface of Gc, Ng_1981 was both in an intracellular pool and extracellularly released from the bacteria, suggesting that Gc employs these two proteins at multiple spatial barriers to fully neutralize lysozyme activity. Together, these findings identify Ng_1063 and Ng_1981 as critical components for Gc defense against lysozyme. These proteins may be attractive targets for antimicrobial therapy aimed to render Gc susceptible to host defenses and/or for vaccine development, both of which are urgently needed against drug-resistant gonorrhea.

Neisseria gonorrhoeae Aggregation Reduces Its Ceftriaxone Susceptibility.

Antibiotic resistance in Neisseria gonorrhoeae (GC) has become an emerging threat worldwide and heightens the need for monitoring treatment failures. N. gonorrhoeae, a gram-negative bacterium responsible for gonorrhea, infects humans exclusively and can form aggregates during infection. While minimal inhibitory concentration (MIC) tests are often used for determining antibiotic resistance development and treatment, the knowledge of the true MIC in individual patients and how it relates to this laboratory measure is not known. We examined the effect of aggregation on GC antibiotic susceptibility and the relationship between bacterial aggregate size and their antibiotic susceptibility. Aggregated GC have a higher survival rate when treated with ceftriaxone than non-aggregated GC, with bacteria in the core of the aggregates surviving the treatment. GC lacking opacity-associated protein or pili, or expressing a truncated lipooligosaccharide, three surface molecules that mediate GC-GC interactions, reduce both aggregation and ceftriaxone survival. This study demonstrates that the aggregation of N. gonorrhoeae can reduce the susceptibility to antibiotics, and suggests that antibiotic utilization can select for GC surface molecules that promote aggregation which in turn drive pathogen evolution. Inhibiting aggregation may be a potential way of increasing the efficacy of ceftriaxone treatment, consequently reducing treatment failure.

Multiwalled Carbon Nanotubes anode with low oxygen content for ascorbic acid fuel cells design

Due to the significance of Ascorbic Acid (AA) fuel cells in biological systems and energy storage applications, the development of efficient electrochemical strategies is needed. In the present work, the electrochemical oxidation of AA is performed with Multiwalled Carbon Nanotubes (MWCNTs) anodes which have controlled oxygen content, modulated by acid reflux treatment. Furthermore, a total oxygen content increase of just 2% on MWCNTs surface was sufficient to achieve an enhanced AA electrocatalytic oxidation. The oxygen content was notoriously lower than other nanocarbon materials like unzipped carbon nanotubes and reduced graphene oxide which normally are considered as optimal materials. The surface chemical composition on MWCNTs was analyzed by XPS. The anodes were prepared as carbon film electrodes (CFE) by dropping cast procedure on GC surface (current collector). Cyclic voltammetry was used to evaluate the electrochemical responses of these electrode materials varying the concentration of AA (10, 50 and 100 mM). At a fixed concentration, the electrochemical responses show an increase in current and a shift of peak potential that facilitate oxidation as the acid treatment time increases. It was found that the COO− groups are responsible for the enhanced catalytic behavior of these modified MWCNTs. The simple change of functional groups by the same acid treatment procedure at different times has a notorious effect on AA oxidation. These findings provide straightforward selection criteria for anodes devoted to AA fuel cell design. Also, it is demonstrated that MWCNTs can still provide new alternatives for enhanced electrocatalytic processes.

A Novel of Multi-wall Carbon Nanotubes/Chitosan Electrochemical Sensor for Determination of Cupric ion

A multi-wall carbon nanotubes/Chitosan electrochemical sensor had been fabricated by dropping CHS/MWNT solution directly onto the GC surface. The sensor was charactered by cyclic voltammetry and AC impedance with K3Fe(CN)6 as a electrochemical probe; Cyclic voltammograms(CV) and electrochemical impedance spectroscopy(EIS) indicated that the active area and electrochemical behavior of the sensor increased and improved significantly after the electrode was modified by carbon nanotubes dispersed by the chitosan. The sensor showed good electrocatalytic activity of K3Fe(CN)6. Also, from the cyclic voltammograms, we can see the process was diffusion controlled on the bare electrode and kinetics and diffusion controlled on the modified electrode. Finally Cu2+ responsed sensitively at the sensor which supplied a new method for the detection of Cu2+.

Formation of nanoporous NiS films from electrochemically modified GC surface with Nickel Hexacyanoferrate film and its performance for the hydrogen evolution reaction

The production of Hydrogen (H2) gas for fuel cell application using electrochemical methods is attracting the attention of the researchers in recent years owing to its high calorific value. Current researchers are enthused to prepare cost effective catalysts from abundant elements in earth crust for the huge production of H2. Recently electrochemical studies are reported based on Metal sulfides and oxides such as MoS2, CoS, WO3 as best catalyst for H2 generation under diverse pH conditions. We focused on preparing nanoporous Nickel Sulfide (NiS) films from Nickel Hexacyanoferrate (NiHCF) nanocubes using electrochemical cycling of the precursor films in Sulfide medium and characterized those using spectroscopy and Microscopy techniques such as FT-IR, Raman spectroscopy, XPS, EDS, XRD, FESEM, AFM, and TEM. The cubic structure of NiHCF gets transformed into NiS cubic skeleton by etching in presence of sulfide ions (S2−). The nanoporous NiS give best results for Hydrogen Evolution Reaction (HER) in the alkali medium. The catalysts were electrochemically modified on glassy carbon surface for electrochemical characterization including Tafel polarization. For comparison, the same procedure was used to prepare other metal sulfides including MnS, FeS, and CoS to compare their catalytic activity towards Hydrogen evolution. Among them, the NiS was shown to be the most efficient electrocatalyst for hydrogen evolution and has shown promise as an alternative to platinum.

Modelling diurnal and seasonal hysteresis phenomena of canopy conductance in an oasis forest ecosystem

Canopy conductance (gc) is considered a key and complex variable in most land surface models. Diurnal hysteretic responses have been observed for gc in relation to its environmental factors, posing some unavoidable challenges for the widely used gc models. This study combined sap flow (SF) methods with eddy covariance (EC) measurements in 2014 to investigate diurnal and seasonal variations in gc during a growing season of an oasis riparian Populus euphratica forest. The results showed that responses of both SF-measured gc and EC-measured surface conductance gs to environmental factors formed hysteresis loops throughout the day. Hysteresis loops of gc existed at different stages of growth and development in this forest and showed significant seasonal variation. A three-step linear model and the Jarvis model were both used to simulate variations in gc. Scalar functions of the Jarvis model showed that midday gc was more sensitive to D in the early growing season (from May to July), and more sensitive to R (except in May) and T in the late growing season (from August to October), while not sensitive to soil water content during the whole growing season. Although the Jarvis model effectively simulated midday gc, the three-step linear model worked more precisely to simulate gc hysteresis loops throughout the growing season (r2=0.88). This study highlighted the importance of dividing the daytime into different time periods and dividing the growing season into different stages to simulate diurnal and seasonal gc hysteresis loops. These results are helpful in achieving a better understanding of the bulk behavior of stomata in response to changing environmental conditions in oasis ecosystems.

PEDOT(PSS) as Solid Contact for Ion-Selective Electrodes: The Influence of the PEDOT(PSS) Film Thickness on the Equilibration Times.

To understand the rate determining processes during the equilibration of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate-based (PEDOT(PSS)-based) solid contact (SC) ion-selective electrodes (ISEs), the surfaces of Pt, Au, and GC electrodes were coated with 0.1, 1.0, 2.0, and 4.0 μm thick galvanostatically deposited PEDOT(PSS) films. Next, potential vs time transients were recorded with these electrodes, with and without an additional potassium ion-selective membrane (ISM) coating, following their first contact with 0.1 M KCl solutions. The transients were significantly different when the multilayered sensor structures were assembled on Au or GC compared to Pt. The differences in the rate of equilibration were interpreted as a consequence of differences in the hydrophilicity of PEDOT(PSS) in contact with the substrate electrode surfaces based on X-ray photoelectron spectroscopy (XPS) and synchrotron radiation-XPS (SR-XPS) analysis of 10-100 nm thick PEDOT(PSS) films. The influence of the layer thickness of the electrochemically deposited PEDOT(PSS)-films on the hydrophilicity of these films has been documented by contact angle measurements over PEDOT(PSS)-coated Au, GC, and Pt electrode surfaces. This study demonstrates that it is possible to minimize the equilibration (conditioning) time of SC ISEs with aqueous solutions before usage by optimizing the thickness of the SC layer with a controlled ISM thickness. PEDOT(PSS)-coated Au and GC electrodes exhibit a significant negative potential drift during their equilibration in an aqueous solution. By coating the PEDOT(PSS) surface with an ISM, the negative potential drift is compensated by a positive potential drift related to the hydration of the ISM and activity changes at the PEDOT(PSS)|ISM interface. The potential drifts related to activity changes in the ISM have been determined by a novel adaptation of the "sandwich membrane" method.

The Reactivity of Selenite toward Methyl Viologen in Mildly Acidic Aqueous Solutions

The chemical and electrochemical reactivity of selenite, SeO32−, toward methyl viologen, MV2+, has been examined in mildly acidic (pH 4) aqueous electrolytes. Solutions containing these two species heated at 60°C for ca. 2 hours, were found to yield both 1-methyl-[4,4’-bipyridine]-1-ium chloride and elemental Se as the main reaction products, as evidenced from information derived from mass spectrometric and spectroscopic techniques. Cyclic voltammetric measurements recorded in acetate buffer (pH 4) with a glassy carbon, GC, electrode bearing a self-assembled monolayer, SAM, of N-ethyl-N’-octadecyl-4,4’-bipyridinium (EOB), which had been exposed to a 100 mM SeO32− solution in aqueous acetate buffer (pH 4) for over 200 min and then rinsed with ultrapure water, displayed a significantly smaller redox peak ascribed to the reduction of the viologen moiety in the EOB SAM. This observation is consistent with the loss of the redox active species within the layer and supports the view that SeO32− can cleave the N-C bond in EOB leading to the release of the viologen group into the solution. Cyclic voltammetric experiments involving a freshly prepared EOB SAM on GC in 1 mM SeO32− in the same buffer yielded a large reduction current with an onset potential virtually identical to that associated with the reduction of the EOB SAM in SeO32−-free solutions. On this basis, the extraordinary shift in the onset of SeO32− reduction induced by the presence of MV2+ in the same electrolyte reported by Koshikumo et al. [Electrochemistry (Tokyo, Jpn.), 81(5), 350 (2013)], may be explained by invoking formation of MV2+ aggregates on the GC surface in amounts too small to be detected by conventional voltammetric techniques.

Te Nanotubes Decorated with Pt Nanoparticles for Fuel Cell Applications

In this communication we report the synthesis, characterization and applications of TeNTs decorated with PtNPs readily prepared by two simple steps to make a GC modified electrode suitable to be used as anode/cathode in fuel cells. In the 1th step the large scale of Te nanotubes synthesis was obtained via a vapor deposition method; then in the 2nd step TeNTs dispersed in methanol react with PtCl2 to make TeNTs/PtNPs. Modified electrodes TeNTs/PtNPs/GC were then made by casting 20 μL of TeNTs/PtNPs/ethanol suspension onto GC surface and left to evaporate at room temperature. The as synthesized hybrid nanostructures, fully characterized by XRD, TEM and XPS analysis, were composed of Te nanotubes decorated with Pt nanoparticles. The electrochemical characterization of TeNTs/PtNPs composite material, performed by cyclic voltammetry (CV), showed exceptional electrocatalytic activity towards methanol oxidations and oxygen reduction.

Highly Sensitive Determination of 4-Nitrophenol at a Nafion Modified Glass Carbon Nanofilm Electrode

In this work, a highly sensitive electrochemical sensor for 4-nitrophenol (4-NP) was facilely constructed based on a Nafion modified glass carbon nanofilm electrode (Nafion-GCNFE). The GCNFE with high activity was quickly fabricated from a smooth GC surface in a blank electrolyte solution of H2SO4 with square wave potential pulses (SWPPs), where the nanofilm formation might be related to repeated anodic oxidation coupled with SO42− intercalation/deintercalation. Moreover, a Nafion modifier can improve the 4-NP adsorption on GCNFE, as confirmed by the Fourier transform infrared spectroscopy (FTIR), and hence increased the differential pulse voltammetry (DPV) response of 4-NP. The influence of pulse potential, pulse time, pulse frequency, and Nafion amount on the DPV signal of 4-NP was investigated in detail. Under an optimized detection condition, the electrochemical sensor based on Nafion-GCNFE exhibited excellent performances in sensing 4-NP with a wide linear range of 10 nM to 50 μM, a very low detection limit of 4 nM (3σ/slope), good reproducibility and reusability, high selectivity and long-term stability (over four weeks), which was successfully used for the 4-NP determination in real water samples with satisfied results.

N-Glycans on the Rift Valley Fever Virus Envelope Glycoproteins Gn and Gc Redundantly Support Viral Infection via DC-SIGN

Rift Valley fever is a mosquito-transmitted, zoonotic disease that infects humans and ruminants. Dendritic cell specific intercellular adhesion molecule 3 (ICAM-3) grabbing non-integrin (DC-SIGN) acts as a receptor for members of the phlebovirus genus. The Rift Valley fever virus (RVFV) glycoproteins (Gn/Gc) encode five putative N-glycan sequons (asparagine (N)–any amino acid (X)–serine (S)/threonine (T)) at positions: N438 (Gn), and N794, N829, N1035, and N1077 (Gc). The N-glycosylation profile and significance in viral infection via DC-SIGN have not been elucidated. Gc N-glycosylation was first evaluated by using Gc asparagine (N) to glutamine (Q) mutants. Subsequently, we generated a series of recombinant RVFV MP-12 strain mutants, which encode N-to-Q mutations, and the infectivity of each mutant in Jurkat cells stably expressing DC-SIGN was evaluated. Results showed that Gc N794, N1035, and N1077 were N-glycosylated but N829 was not. Gc N1077 was heterogeneously N-glycosylated. RVFV Gc made two distinct N-glycoforms: “Gc-large” and “Gc-small”, and N1077 was responsible for “Gc-large” band. RVFV showed increased infection of cells expressing DC-SIGN compared to cells lacking DC-SIGN. Infection via DC-SIGN was increased in the presence of either Gn N438 or Gc N1077. Our study showed that N-glycans on the Gc and Gn surface glycoproteins redundantly support RVFV infection via DC-SIGN.

Electrochemically formed 3D hierarchical thin films of cobalt–manganese (Co–Mn) hexacyanoferrate hybrids for electrochemical applications

Here we report the feasibility of forming 3D nanostructured hexacyanoferates of Cobalt and Manganese (Co–MnHCF) on GC surface by a facile electrochemical method. This 3D architecture on glassy carbon electrode characterised systematically by voltammetry and other physical characterisation techniques like Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform Infrared spectroscopy (FTIR) etc,. Electrochemical Quartz crystal microbalance (EQCM) studies helped out to calculate the total mass change during Co–MnHCF formation. Electrochemical studies reveal that the formal redox potentials of both Co and MnHCF films remained close to that of newly formed Co–MnHCF hybrid films. These 3D modified films were successfully applied for two different electrochemical applications i) For pseudocapacitor studies in KNO3 medium ii) Investigated the electrocatalytic behaviour of redox film towards water oxidation reaction in alkaline medium. Electrochemical performances of newly formed Co–MnHCF are compared with their individual transition metal (Co, Mn) hexacyanoferrates. The resulting material shows a specific capacitance of 350 F g−1 through its fast reversible redox reaction of electrochemically formed Co–MnHCF modified film. Interestingly we showed the overpotential of 450 mV (from its thermodynamic voltage 1.2 V) to attain its optimum current density of 10 mA cm−2 for O2 evolution in alkaline medium.

Phenothiazines grafted on the electrode surface from diazonium salts as molecular layers for photochemical generation of singlet oxygen

Four amine-derivative phenothiazines were converted to the corresponding diazonium salt forms prior to their electrochemical grafting on the GC electrode with the aim to assess their ability to generate singlet oxygen. It was demonstrated by cyclic voltammetry and XPS spectroscopy that the molecular layers were effectively bound to the GC surface by applying the reductive potential in situ in the reaction diazo-mixture. The chosen procedure without the product separation step, appears to be especially useful due to the high solubility of the resulted phenothiazine diazonium salts. The effectiveness of singlet oxygen generation was measured for all of the grafted surfaces by UVVis spectra monitoring of the adjacent solution phase of 1,3-diphenylisobenzofuran (DPBF), which is well known trapping molecule used in detection of singlet oxygen. The data presented in the work prove that all of the molecular layers are effective singlet oxygen generators that might be used for various areas of applications where a highly oxidative reactant is required.

Fast Crystal Growth in o-Terphenyl Glasses: A Possible Role for Fracture and Surface Mobility.

Molecular liquids can develop a fast mode of crystal growth ("GC growth") near the glass transition temperature. This phenomenon remains imperfectly understood with several explanations proposed. We report that GC growth in o-terphenyl conserves the overall volume, despite a 5% higher density of the crystal, and produces fine crystal grains with the same unit cell as normally grown crystals. These results indicate that GC growth continuously creates voids and free surfaces, possibly by fracture. This aspect of the phenomenon has not been considered by previous treatments and is a difficulty for those models that hypothesize a 5% strain without voids. Given the existence of even faster crystal growth on the free surface of molecular glasses, we consider the possibility that GC growth is facilitated by fracture and surface mobility. This notion has support from the fact that GC growth and surface growth are both highly correlated with surface diffusivity and with fast crystal growth along preformed cracks in the glass.

A Glucose Fuel Cell with Graphene-Coated Carbon Fiber Cloth

Enzymatic glucose biofuel cells that generate power in human body fluids have been strongly demanded to supply electric power to microelectric systems such as heart pacemakers. This is because they work under mild conditions of room temperature, neutral pH and atmospheric pressure, which make them amenable to the human body. Porous carbon electrodes have been commonly used in glucose biofuel cells [1]. However, it was not very easy to avoid release of enzymes form these porous carbon electrode during operation of the biofuel cells. In addition, these porous carbon films were not flexible, and they were easily fractured. On the other hand, a carbon fiber woven fabric (CF) has been reported to have high flexibility and conductivity. Moreover, there were some trials to deposit graphene on each carbon fibers in CF, and it is called as graphene-coated carbon fiber cloth(GC) [2]. Thus, it is considered to be possible to increase the effective surface areas to absorb more enzymes on GC surface. In this study, a glucose fuel cell was fabricated using GC as flexible electrodes in glucose biofuel cells. The SEM image of the GC used in this study is shown in Fig. 1. Many nanostructures were observed on carbon fibers. We used this GC as the anode and cathode of the fabricated micro biofuell cells, and the area of the anode and cathode electrodes were 3 × 10 mm2, respectively. The anode was modified with glucose oxidase (GOD) and ferrocene. The cathode was modified with bilirubin oxidase (BOD). Figure 2 shows comparison of the relationship of the power density and voltage of biofuell cells using GC or CF. The power was measured by immersing the biofuel cells in phosphate buffer solution with 100 mM glucose at room temperature. The maximum power for the CF biofuel cell was 16.3 μW / cm2 at 0.07 V, and the maximum power for GC biofuel cell was 30.7 μW / cm2 at 0.096 V. These results indicated the advantages of using GC on flexible glucose biofuel cells. [1] M. Togo, A. Takamura, T. Asai, H. Kaji, M. Nishizawa, Electrochim. Acta 52(2007) pp.4669–4674. [2] http://incu-alliance.co.jp/

Effect Of Obesity On Leukocyte Activation In Response To 1 Bout of High-Intensity Interval Exercise In Children

Adult and childhood obesity are associated with chronic inflammation. While exercise is known to improve cardiovascular health via modulation of inflammatory processes, including activation of circulating leukocytes (WBC), underlying biochemical mechanisms are not well defined, especially in children. Understanding these mechanisms may optimize effectiveness of exercise interventions. PURPOSE: To evaluate the extent of circulating WBC activation in obese and non-obese children during high-intensity interval cycling. METHODS: 12 obese (BMI >95% or Body fat % >35) and 9 non-obese children (10-17 yrs) underwent a high-intensity, cycle ergometer interval exercise challenge (10 sets of 2 min cycling at 80% peak VO2 + 1 min rest). Baseline, end-exercise, and 1 hour post-exercise blood samples were antibody-stained for cell surface marker analysis by flow cytometry. The inflammatory activation profile of neutrophils (Gc) was assessed by fluorescence intensity of CD11b, CD66b and CD62L. RESULTS: (see figure) At baseline, Gc CD11b expression was comparable across groups, but Gc counts were 31% greater (4.2±0.4 vs. 3.2±0.3 x1000/ul) in obese vs non-obese children. Both CD11b expression and Gc counts increased similarly in both groups at end-exercise, and resumed near-baseline values by 1 hr post exercise. CONCLUSION: While our experimental exercise format had similar effects on Gc counts and surface marker expression across groups, consistently higher cell counts indicate a greater exposure to pro-inflammatory stimuli in obese children. Investigating these responses across different exercise paradigms may help identify which exercise interventions display the most effective pattern of inflammatory modulation in pediatric obesity and other dysmetabolic conditions. Support: NIH Grants NICHD P01HD048721 & UL1 TR000153, UCI Newkirk Center

Spatiotemporal variations of T/ET (the ratio of transpiration to evapotranspiration) in three forests of Eastern China

Evapotranspiration (ET), which is comprised by evaporation from soil surface (E), transpiration (T) and evaporation from the intercepted water by canopy (EI), plays an important role in maintaining global energy balance and regulating climate. Quantifying the spatiotemporal variations of T/ET (the ratio of T to ET) can improve our understandings on the role of vegetation ecophysiological processes in climate regulation. Using eddy covariance measurements at three forest ecosystems (Changbaishan temperate broad-leaved Korean pine mixed forest (CBS), Qianyanzhou subtropical coniferous plantation (QYZ) and Dinghushan subtropical evergreen mixed forest (DHS)) in north–south transect of Eastern China (NSTEC), we run the revised Shuttleworth–Wallace model (S–W model), validated its performance with the water vapor fluxes measured at two layers, and quantified the spatiotemporal variations of T/ET. The S–W model performed well in simulating ET and T/ET. The mean value of annual T/ET at three forests during the observation period all exceeded 0.6. The diurnal variation of canopy stomal conductance (Gc) dominated that of T/ET. The seasonal dynamics of T/ET was mainly shaped by that of leaf area index (LAI), vapor pressure deficit (VPD) and air temperature (Ta) through altering Gc and the portion that the energy absorbed by canopy (PEC) at temperate forest (CBS), while the seasonal dynamics of T/ET at subtropical forests (QYZ and DHS) were mainly affected by Ta, net radiation, VPD, and soil water content through altering Gc and soil surface conductance (Gs). The variation of mean annual Gc governed the interannual varaition and spatial variation of T/ET. Therefore, forests in Eastern China played an important role in regulating climate through T and Gc primarily affected the spatial and temproal variations of the role of forest T in regulating climate.