Effects of preparation temperature on electrochemical performance of nitrogen-enriched carbons

The activated nitrogen-enriched novel carbons (NENCs) were prepared by direct carbonization using polyaniline coating activated mesocarbon microbead composites as the precursor. Herein the influences of the carbonization temperature on the structure and morphology of the NENCs samples were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 adsorption/desorption isotherm at 77 K. The electrochemical properties of the supercapacitors were characterized by cyclic voltammetry, galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS), cycle life, leakage current and self-discharge measurements in 6 mol/L KOH solution. The results demonstrate that the NENC samples carbonized at 600 °C show the highest specific capacitance of 385 F/g at the current density of 1 A/g and the lowest ESR value (only 0.93?). Furthermore, the capacity retention ratio of the NENCs-600 supercapacitor is 92.8 % over 2500 cycles.

The dating and temperature measurement technologies for carbonate minerals and their application in hydrocarbon accumulation research in the paleouplift in central Sichuan Basin, SW China

A new method for reconstructing the geological history of hydrocarbon accumulation is developed, which are constrained by U-Pb isotope age and clumped isotope((35)47) temperature of host minerals of hydrocarbon-bearing inclusions. For constraining the time and depth of hydrocarbon accumulation by the laser in-situ U-Pb isotope age and clumped isotope temperature, there are two key steps:(1) Investigating feature, abundance and distribution patterns of liquid and gaseous hydrocarbon inclusions with optical microscopes.(2) Dating laser in-situ U-Pb isotope age and measuring clumped isotope temperature of the host minerals of hydrocarbon inclusions. These technologies have been applied for studying the stages of hydrocarbon accumulation in the Sinian Dengying gas reservoir in the paleo-uplift of the central Sichuan Basin. By dating the U-Pb isotope age and measuring the temperature of clumped isotope((35)47) of the host minerals of hydrocarbon inclusions in dolomite, three stages of hydrocarbon accumulation were identified:(1) Late Silurian: the first stage of oil accumulation at(416±23) Ma.(2) Late Permian to Early Triassic: the second stage of oil accumulation between(248±27) Ma and(246.3±1.5) Ma.(3) Yanshan to Himalayan period: gas accumulation between(115±69) Ma and(41±10) Ma. The reconstructed hydrocarbon accumulation history of the Dengying gas reservoir in the paleo-uplift of the central Sichuan Basin is highly consistent with the tectonic-burial history, basin thermal history and hydrocarbon generation history, indicating that the new method is a reliable way for reconstructing the hydrocarbon accumulation history.

Presence of Antibodies to Heat Stress Proteins and its Possible Significance in Workers Exposed to High Temperature and Carbon Monoxide

Antibodies to the ubiquitous group of stress proteins known as heat shock proteins (Hsps) have been found to be associated with a number of diseases in humans. Hsps are known to be induced by certain xenobiotics, some of which are common in the working environment. The biological significance of the presence of such autoantibodies is presently unclear. In the present study, we used immunoblotting to investigate the presence of antibodies against the different stress proteins, Hsp27, Hsp60, Hsp71, Hse (heat shock cognate ) 73 and Hsp89a and D in groups of workers exposed to high temperature or carbon monoxide. These data were related to a detailed clinical evaluation and to various laboratory measurements including electrocardiogram (ECG), B echogram, white blood cell counts and typing, the activity of alanine aminotransferase (ALT), acid phosphatase (ACP) and alkaline phosphatase (ALP) and lymphocyte DNA damage. Antibodies to Hsp27 and Hsp71 were found more frequently in the high temperature and carbon monoxide-exposed groups than in controls (P (0.05 ). The carbon monoxide-exposed group showed the highest incidence of anti-Hsp antibodies. Anti-Hsp60 antibodies were only detected in workers exposed to high temperature or carbon monoxide. The percentage of workers with abnormal ECG, B echogram changes and displaying hepatitis B antigen (HBsAg ) was higher in the carbon monoxide group than in the control group (P＜0.05 ).There was a significant inerease in the activity of ALT in the high temperature and carbon monoxide groups and in the activities of ACP and ALP in the carbon monoxide group (P＜0.05 ). The extent of DNA damage measured in lymphoeytes was higher in workers from the high temperature and carbon monoxide-cxposed groups. We suggest that the increased frequeney of antibodies to Hsps is the result of these damages, of the release of denatured Hsps and of a decrease in the phagocytic ability of macrophages in these workers. The data gathered in the present study show a statistical relation between the occurrence of antibodies against Hsps and the frequency of health problems in workers and suggest a potential role for the antibodies as useful biomarkers to assess whether workers are experieneing environmental stress

The Combined Effects of High Temperature and Carbon Monoxide on Heat Stress Response

In this study,we have examined the effects of exposure to high temperature, carbon inonoxideor a combination of both conditions in a model system,the rat and in industrial workers.In the rat liver, HSP70 mRNA and HSP70 synthesis were measured by dot hybridization and western blot. The results showed that after a heat stress HSP70 mRNA and its product, HSP70 increased significantly and there was a synergism in the combined effects of high temperature and carbon monoxide exposure on the induction of HSP70 mRNA and HSP70 synthesis. Heat played a major role in this induction. The presence of antibodies to human HSP27, HSP60, HSP70,HSC73, HSP89 αand β in workers exposed to heat, carbon monoxide was also measured by western blot using purified HSPs as antigens. Plasma free amino acids were measured in the saine group of workers. The incidence of antibodies to HSP27 and HSP70 Was significantly higher in the workers working in an environment with extreme heat, and high carbon monoxide ernission than in a control group. The carbon monoxide exposed group showed the highest incidence of antibodies to HSPs. Although our previous results indicated that workers had an insufficient protein intake,plasma free amino acids tended to increase, especially in methionine and tryptophan two kinds of amino acids which are absent from the main stress protein, HSP70.These results suggest that the major problems that these workers may face are how to facilitate the use of plasma free amino acids and reduce the inhibition of synthesis of normal proteins when they are exposed to occupational harmful factors.These resultsalso add new information on the measurement of HSPs as a potential biomonitor to assess whether organisms are experiencing metabolic stress within their environment.

Effect of temperature and stress on molecular structure and carbon monoxide generation of lignite from Kailuan mining area

In order to analyze the origin of carbon monoxide(CO) in coal seams, stress–strain experiments under temperature of 50, 150 and 250 °C were conducted using lignite from Kailuan mining area. Fourier transform infrared spectroscopy and elemental analysis were carried out before and after deformation of the samples. The results indicated that CO generated at 150 and 250 °C; the gas component was mostly oxygen(O_2), with small amount of carbon dioxide(CO_2), methane(CH_4) and hydrogen(H_2). At 50 °C, O_2 and a little CO_2 were observed and no CO was found. The carbon content of the coal samples increased slightly after deformation, and the oxygen content, H/C ratio, and O/C ratio decreased. The molecular structure of coal displayed different evolution characteristics at various temperatures. At 50 and 150 °C, the falling off of side chains, broken of ether bond and directional realignment of the aliphatic chains resulting in the formation of long chains were the main performance of coal molecular structure evolution. While at 250 °C, the side chains fell off and short chains formed. Furthermore, at both 150 and 250 °C, condensed degree of aromatic ring increased. Under the action of temperature and pressure, CO forms in two ways.The first is that ether bond breaks, oxygen and carbon atoms combine together and forms CO, or O_2 forming in the broken of ether–oxygen bond leads to the oxidation of free radicals and resulting in the formation of CO. And the second is that CO derives from falling off of C=O group.

Decomposition Temperature of Cold Seep Carbonate and its Relationship with Delta Carbonate

Delta carbonate （Delta C, AC） method is a commonly- used surface geochemical exploration method for petroleum surveys. Delta C holds that light hydrocarbon gases leak into near-surface soils or sediments from underlying petroleum accumulations, then partly oxidized to CO2, resulting in a special carbonate precipitation, which is termed as Delta carbonate （△C）.

Deposition of Amorphous Carbon Films using ECR Plasma byVarying the Substrate Temperature

Amorphous hydrogenated carbon thin films have been deposited with benzene plasma in an electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition system. The characteristic of Benzene discharge plasma has been monitored by Mast spectrometry. It shows that the majority of the plasma species in the downstream ECR Plasma with benzene as gas source are acetylene, ethylene and higher mass species. In the experiments, the effects of the substrate temperature on the deposition rates have been emphatically studied. The structures of the films were analyzed by FTIR and Ramam spectrum.The results show that when the substrate temperature rises, the deposition rate drops down, the hydrogen Foment decreases, with the higher SP3 content being presented in the film.

Impact of Temperature Variation on Performance of Carbon Nanotube Field-Effect Transistor-Based on Chaotic Oscillator:A Quantum Simulation Study

We evaluate the impact of temperature on the output behavior of a carbon nanotube field effect transistor （CNFET） based chaotic generator. The sources cause the variations in both current-voltage characteristics of the CNFET device and an overall chaotic circuit is pointed out. To verify the effect of temperature variation on the output dynamics of the chaotic circuit, a simulation is performed by employing the CNFET compact model of Wong et al. in HSPICE with a temperature range from -100℃ to 100℃. The obtained results with time series, frequency spectra, and bifurcation diagram from the simulation demonstrate that temperature plays a significant role in the output dynamics of the CNFET-based chaotic circuit. Thus, temperature-related issues should be taken into account while designing a high-quality chaotic generator with high stability.

Properties of Activated Carbons from Sugarcane Leaves and Rice Straw Derived Charcoals by Activation at Low Temperature via KMnO_(4)Pre-Oxidation-Hydrolysis

Activated carbon preparation from sugarcane leaves and rice straw by carbonization(250℃–400℃)and activation at 500℃were studied.The effects of pre-oxidation,hydrolysis of derived charcoals by boiled KMnO4 aqueous solution were evaluated.The derived charcoals products were pretreated using oxidation-hydrolysis with 1–5 wt.%KMnO4 at 100℃and then activated at 500℃.The derived charcoal and activated carbon products were characterized by FTIR,XRD,SEM-EDS and BET.Iodine number and methylene blue number of derived products were also used for the analysis of the products.It was found that fabricated charcoal materials made at 350℃–400℃possess good characteristics with low content of surface functional groups and high carbon content.After pre-oxidation-hydrolysis and activation at 500℃,the resulting derived activated carbon materials from charcoals with 400℃carbonization temperature have high content of oxygen containing surface functional groups such as Mn-O,Si-O,Si-O-Si,C-O,or O-H.In addition,MnO_(2) accumulated on the surface of the derived activated carbon products.The surface area and pore volume of the activated carbon products have also increased with increasing of KMnO_(4) concentration from 1 to 3 wt.%and then decreased with 5 wt.%used during activation.Therefore,activated carbon products made by pre-oxidation-hydrolysis with 3 wt.%KMnO_(4) were used for Fe(Ⅲ)adsorption experiments.It was found that Fe(Ⅲ)adsorption on the activated carbon materials can be fitted with both the Freundlich and the Langmuir models.The calculated maximum Fe(Ⅲ)adsorption capacities of sugarcane leaves derived activated carbon and rice straw derived activated carbon products were 50.00 and 39.37 mg/g,respectively.It was shown that the effect of pre-oxidation-hydrolysis by KMnO_(4) and activation at 500℃are beneficial for activated carbon preparation with environmentally friendly and low-cost simplified operation.

Influence of Climate on Soil Organic Carbon in Chinese Paddy Soils

Soil organic carbon(SOC) is a major component of the global carbon cycle and has a potentially large impact on the greenhouse effect. Paddy soils are important agricultural soils worldwide, especially in Asia. Thus, a better understanding of the relationship between SOC of paddy soils and climate variables is crucial to a robust understanding of the potential effect of climate change on the global carbon cycle. A soil profile data set(n = 1490) from the Second National Soil Survey of China conducted from 1979 to 1994 was used to explore the relationships of SOC density with mean annual temperature(MAT) and mean annual precipitation(MAP) in six soil regions and eight paddy soil subgroups. Results showed that SOC density of paddy soils was negatively correlated with MAT and positively correlated with MAP(P < 0.01). The relationships of SOC density with MAT and MAP were weak and varied among the six soil regions and eight paddy soil subgroups. A preliminary assessment of the response of SOC in Chinese paddy soils to climate indicated that climate could lead to a 13% SOC loss from paddy soils. Compared to other soil regions, paddy soils in Northern China will potentially more sensitive to climate change over the next several decades. Paddy soils in Middle and Lower Yangtze River Basin could be a potential carbon sink. Reducing the climate impact on paddy soil SOC will mitigate the positive feedback loop between SOC release and global climate change.

Effect of carboxymethyl cellulose on dissolution kinetics of carboxymethyl cellulose-sodium carbonate two-component tablet

Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium carbonate tablets are carried out at various temperatures.The dissolution process of each tablet is measured by electrical conductivity tracking method and the concentration of dissolved sodium carbonate is quanti fied with calibrated conductivity-concentration converting equation of sodium carbonate.The quanti fied dissolution data is fitted with both surface reaction model and diffusion layer model and the results clearly show that surface reaction model is suggested as the appropriate dissolution model for all measured tablets.Therefore,it is determined that carboxymethyl cellulose is a stable element to remain the dissolution mechanism of tablet unchanged.The dissolution rate constant quanti fied with surface reaction model presents that carboxymethyl cellulose-sodium carbonate two-component tablets obtain signi ficant higher dissolution rate constant than pure sodium carbonate tablet and higher proportion of carboxymethyl cellulose leads to apparent higher dissolution rate constant.The results prove for the usage of carboxymethyl cellulose in most practical applications at a relative low-level,the effect of carboxymethyl cellulose is effective and positive for two-component tablet to enhance the dissolution process and improve dissolution rate constant and this effect is speculated coming from its dynamic physical transforming process in water including dilation and conglutination.

Facile Oxygen-promoted Synthesis of Cu,N Co-doped Carbon Composites for Oxygen Reduction

A new strategy to fabricate oxygen-promoted Cu,N co-doped carbon(OP-CuN@C)composites is reported.The strategy consists of only two simple steps:chemical polymerization and high temperature carbonization.Electrochemical measurements were conducted to investigate the catalytic activity and mechanism of ORR on the resulting samples.All the electrochemical results indicate that OP-CuN@C exhibits the best ORR catalytic activity.The ORR onset potential of OP-CuN@C is slightly lower than that of commercial Pt/C catalyst.The good performance is attributed to the large specific surface area,high content of heteroatoms(pyridinic,graphitic nitrogen,and oxygen atom)and synergistic effect between divalent copper and nitrogen dopant.

Variation of Soil CO_2 Flux and Carbon Density in Three Apline Meadows

Three alpine meadows were chosen from the eastern margin of the Qilian Mountain：Polygonum viviparum meadow（P）,Stipa capillata grassland（S）and Rhododendron simsii shrub meadow（R）;LI-8100 A soil CO2 flux auto-monitoring system and lab analysis were applied to analyze the soil organic carbon density,dynamics of carbon flux,and their relationship with environmental factors.The results showed that different vegetations varied greatly in soil organic carbon density：R 〉 S 〉 P,and the soil carbon density reduced with the increasing depth;soil CO2flux：S 〉 P 〉 R,and sample plot P and S showed unimodal changes.The peak values appeared at 14：00-15：00 p.m.;soil CO2 flux was negatively correlated with near-ground air humidity and carbon content,positively correlated with soil temperature and near-ground air temperature,and showed no obvious correlation with soil moisture.

Effects of ionic strength and temperature on the aggregation and deposition of multi-walled carbon nanotubes

The aggregation and deposition of carbon nanotubes（CNTs） determines their transport and fate in natural waters.Therefore,the aggregation kinetics of humic-acid treated multi-walled carbon nanotubes（HA-MWCNTs） was investigated by time-resolved dynamic light scattering in NaCl and CaCl_2 electrolyte solutions.Increased ionic strength induced HA-MWCNT aggregation due to the less negative zeta potential and the reduced electrostatic repulsion.The critical coagulation concentration（CCC） values of HA-MWCNTs were 80 mmol/L in NaCl and 1.3 mmol/L in CaCl_2 electrolyte,showing that Ca^（2＋） causes more serious aggregation than Na~＋.The aggregation behavior of HA-MWCNTs was consistent with Derjaguin-Landau-Verwey-Overbeek theory.The deposition kinetics of HA-MWCNTs was measured by the optical absorbance at 800 ran.The critical deposition concentrations for HA-MWCNT in NaCl and CaCl_2 solutions were close to the CCC values,therefore the rate of deposition cannot be increased by changing the ionic strength in the diffusion-limited aggregation regime.The deposition process was correlated to the aggregation since larger aggregates increased gravitational deposition and decreased random Brownian diffusion.HA-MWCNTs hydrodynamic diameters were evaluated at 5,15 and 25℃.Higher temperature caused faster aggregation due to the reduced electrostatic repulsion and increased random Brownian motion and collision frequency.HA-MWCNTs aggregate faster at higher temperature in either NaCl or CaCl_2electrolyte due to the decreased electrostatic repulsion and increased random Brownian motion.Our results suggest that CNT aggregation and deposition are two correlated processes governed by the electrolyte,and CNT transport is favored at low ionic strength and low temperature.

Temperature stability of symmetric activated carbon supercapacitors assembled with in situ electrodeposited poly (vinyl alcohol) potassium borate hydrogel electrolyte

The temperature stability of supercapacitor（SC） is largely determined by the properties of the electrolyte.Hydrogel electrolytes（HGE）, due to their hydrophilic polymer skeleton, show different temperature stability to that of liquid aqueous electrolytes. In this study, symmetric activated carbon（AC） SCs had been assembled with in situ electrodeposited poly（vinyl alcohol） potassium borate（PVAPB） HGE. The electrochemical performance of the SCs was systematically studied at different temperatures. Results show that the conductivity of PVAPB HGE is comparable with that of liquid aqueous electrolytes at different temperatures. The operating temperature range of PVAPB HGE SCs is -5–60°C, while those of the 1 mol/L Na2SO4SCs and the 0.9 mol/L KClSCs are 20–80°C and 20–40°C, respectively. The specific capacitance of PVAPB HGE SC is higher than those of SCs using liquid aqueous electrolytes at any temperature. The excellent temperature stability of PVAPB HGE makes it possible to build stable aqueous SCs in the wider temperature range.

Degradation of ofloxacin using peroxymonosulfate activated by nitrogen-rich graphitized carbon microspheres:Structure and performance controllable study

Nitrogen-rich graphitized carbon microspheres(NGCs)with hierarchically porous were constructed by self-assembly.Under different heat treatment conditions,the structure,morphology and properties of NGCs were studied by using multiple characterization techniques.The results showed that the chemical microenvironments(e.g.surface chemistry,degree of graphitization and defective,etc.)and microstructures properties(e.g.morphology,specific surface area,particle size,etc.)could be delicately controlled via thermal carbonization processes.The degradation of ofloxacin(OFLX)by NGCs activated peroxymonosulfate(PMS)was studied systematically.It was found that the synergistic coupling effect between optimum N or O bonding species configuration ratio(graphitic N and C=O)and special microstructure was the main reason for the enhanced catalytic activity of NGC-800(calcination temperature at 800°C).Electron paramagnetic resonance(EPR)experiments and radical quenching experiments indicated that the hydroxyl(·OH),sulfate(SO4^·-)and singlet oxygen(^1O_(2))were contributors in the NGC-800/PMS systems.Further investigation of the durability of chemical structures and surface active sites revealed that undergo N bonding species configuration reconstruction and cannibalistic oxidation during PMS activation reaction.The used NGC-800 physicochemical properties could be recovered by heat treatment to achieve the ideal catalytic performance.The findings proposed a valuable insight for catalytic performance and controllable design of construction.

Facile synthesis of nitrogen-doped graphene aerogels functionalized with chitosan for supercapacitors with excellent electrochemical performance

Three-dimensional porous nitrogen-doped graphene aerogels（NGAs） were synthesized by using graphene oxide（GO） and chitosan via a self-assembly process by a rapid method.The morphology and structure of the as-prepared aerogels were characterized.The results showed that NGAs possesed the hierarchical pores with the wide size distribution ranging from mesopores to macropores.The NGAs carbonized at different temperature all showed excellent electrochemical performance in 6 mol/L KOH electrolyte and the electrochemical performance of the NGA-900 was the best.When working as a supercapacitor electrode,NGA-900 exhibited a high specific capacitance（244.4 F/g at a current density of 0.2 A/g）,superior rate capability（51.0% capacity retention） and excellent cycling life（96.2% capacitance retained after 5000 cycles）.

Cooperative effect from cation and anion of pyridine-containing anion-based ionic liquids for catalysing CO_2 transformation at ambient conditions

Pyridine-containing anion-based ionic liquids(PA-ILs) with two kinds of interaction sites to bind CO_2, e.g., [P4444][2-OP], were found to be highly efficient for catalysing the cycloaddition reactions of atmospheric CO_2 with epoxides at room temperature under metal-and halogen-free conditions, producing a series of cyclic carbonates in high yields. It was demonstrated that the cooperative interaction from two interaction sites in the anions of PA-ILs activated CO_2, while the cation activated the epoxides substrates via coordination to the central P+ unit, thus resulting in the high activity of the IL catalysts.

Effect of Metal Oxide on Electrical Resistivity of Conductive Wood Charcoal

To analyze the effect of metal oxide on electrical resistivity of conductive wood charcoal,wood powder of Masson pine was mixed with ferric oxide (Fe_2O_3) and nickel oxide (NiO), respectively,and then the mixed powders were carbonized at high temperature in a laboratory-scale tube furnace in a nitrogen atmosphere. DCY-3 resistivity tester was used to measure electrical resistivity of conductive wood charcoal. When carbonization temperature was 1200 ℃, the electrical resistivity of controlsamples, Fe_2O_3 (4%) added samples, and NiO (4%) added samples was 0.104 Ω·lcm, 0.071 Ω·lcm, and 0.066 Ω·lcm, respectively. When carbonization temperature was 1 500 ℃, the electrical resistivity of control samples, Fe_2O_3 (4%) added samples, and NiO(4%) added samples was 0.091 Ω·lcm,0.052 Ω·lcm, and 0.052Ω·lcm, respectively. And electrical resistivity of conductive wood charcoaldecreased from 0.060Ω·lcm to 0.041Ω·lcm when the ferric oxide addition increased from 2% to 10%.The results showed that the electrical resistivity of conductive wood charcoal decreased with the increase of carbonization temperature. Ferric oxide and nickel oxide could be used as catalysts todecrease electrical resistivity of conductive wood charcoal. And electrical resistivity of conductivewood charcoal reduced with increasing the ferric oxide addition.