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.

Effects of coal rank, Fe_3O_4 amounts and activation temperature on the preparation and characteristics of magnetic activated carbon

Coal-based Magnetic Activated Carbons （CMAC＇s） were prepared from three representative coal samples of various ranks： Baorigele lignite from Inner Mongolia; Datong bitumite from Shanxi province; and Taixi anthracite from Ningxia Hui Auto- nomous Region. Fe3O4 was used as a magnetic additive. A nitrogen-adsorption analyzer was used to determine the specific surface area and pore structure of the resulting activated carbons. The adsorption capacity was assessed by the adsorption of iodine and methylene blue. X-ray diffraction was used to measure the evolution behavior of Fe304 during the preparation process. Magnetic properties were characterized with a vibrating-sample magnetometer. The effect of the activation temperature on the performance of CMAC＇s was also studied. The results show that, compared to Baorigele lignite and Taixi anthracite, the Datong bitumite is more appropriate for the preparation of CMAC＇s with a high specific surface area, an advanced pore structure and suitable magnetic properties. Fe304 can effectively enhance the magnetic properties and control the pore structure by increasing the ratio of meso- pores. An addition of 6.0% Fe304 and an activation temperature of 880 ℃ produced a CMAC having a specific surface area, an iodine adsorption, a methylene blue adsorption and a specific saturation magnetization of 1152.0 m2/g, 1216.7 mg/g, 229.5 mg/g and 4.623 emu/g, respectively. The coal used to prepare this specimen was Datong bitumite.

Characteristics of the dynamic changes in active accumulated temperature in Sichuan,China in the last 51 years against the background of climate change

It is of utmost necessity to understand the dynamics of regional active accumulated temperature(AAT)to cope with the negative impacts of global warming on agroforestry development and food security and to provide a real-time and effective reference basis for regional agroforestry planning.The daily temperature data from 30 meteorological stations in Sichuan Province from 1970 to 2020,and sea surface temperature(SST)index data from the Atlantic Multiphase Oscillation(AMO)and Pacific Decadal Oscillation(PDO)were used for the study.Sichuan Province was divided into the western region(WS)and the eastern region(ES),considering 1000 m above sea level as the boundary.The spatiotemporal characteristics of≥0℃ and≥10℃ active accumulated temperature(AAT0,AAT10)in WS and ES were analyzed comprehensively using 5-day average sliding,empirical orthogonal function(EOF),ensemble empirical mode decomposition(EEMD),and multiple mutation tests.The results show that(1)AAT0 and AAT10 of WS ranged from 3034℃ to 3586℃ and 1971℃ to 2636℃,respectively,while the AAT0 and AAT10 of ES ranged from 5863℃ to 6513℃ and 4847℃ to 5875℃,respectively.The period around 1997 was a significant abrupt change,and the AAT in the province generally increased during the subsequent time period(2)AAT in the study area is mainly driven by the fluctuations of AMO,as reflected by the low-to-high variation of AAT coinciding with the jump of the cold-to-warm phase of AMO.Considering different time scale fluctuations in the past 51 years,the major cycle for both AAT0 and AAT10 in WS is 3.40 a,while the major cycles in ES are 3.64 a and 3.19 a,respectively with a sub-cycle of 7.29 a.AAT fluctuation has an insignificant periodic characteristic of 25.50 a on the interdecadal scale(3)The spatial heterogeneity of AAT in WS is prominent and is mainly reflected by the significantly warm conditions in the south of the WS region and relatively slight warm conditions in the north,as well as by the isolated cooling area in the form of"freezing point",i.e.,Xiaojin county.In contrast,the spatial variability of AAT in ES is more or less consistent,with the warming areas concentrated in the foothills of the western edge of the basin and a slight increase in AAT observed in the central part of the basin.

An active temperature compensated fiber Bragg grating vibration sensor for high-temperature application

An active temperature compensated fiber Bragg grating(FBG)vibration sensor with a constant section cantilever beam is proposed for the simultaneous measurement of temperature and vibration,and the sensor is verified by a temperature compensation feedback system.The high-temperature vibration sensor is composed of a quartz cantilever beam and a femtosecond Bragg grating.The feedback control demodulation system of active temperature compensation can adjust the laser wavelength to stabilize the grating offset point and realize simultaneous measurement of temperature and vibration.On this basis,the performance of the sensor is tested and analyzed within the range of 20-400℃by setting up a high-temperature vibration test system.The experimental results show that the sensitivity of the sensor is about 132.33 mV/g,and the nonlinearity is about 3.33%.The sensitivity between the laser wavelength and temperature is about 0.01307 nm/℃.In addition,the active temperature compensated fiber Bragg grating vibration sensor has the advantages of a simple structure,stable performance,easy demodulation and high sensitivity.Moreover,the sensor can achieve high temperature vibration signal monitoring and has good practical application value.

Compositions,Proportions,and Equilibrium Temperature of Coexisting Two-feldspar in Crystalline Rocks

Compositions, proportions, and equilibrium temperature of coexisting two-feldspar in crystalline rocks are of great importance to classification in petrography and interpretation of petrogenesis. Crystalline rocks are usually composed of 4-6 minerals （phases）, depending on their independent chemical components and the equilibrium temperature of crystallizations. In general, number of mineral phases can be determined by the ＂Phase Rule＂. According to the mass balance principle, bulk composition of coexisting two-feldspar could be evaluated from the bulk chemistry of a rock, provided that the compositions of the coexisting mafic mineral phases containing calcium, sodium, and potassium oxides are determined, e.g., by microprobe analysis. The compositions, proportions, and temperature of two-feldspar in equilibrium can thus be simultaneously resolved numerically from bulk composition of the rock, by incorporating the activity/composition relations of the ternary feldspars with the mass balance constraints. Upon the numerical approximation method presented in this paper, better-quality, internally consistent data on feldspar group could usually be obtained, which would be expected more realistic and accurate in consideration of thermodynamic equilibria in the system of crystalline rocks, as well as bulk chemistry of a rock and the composing minerals.

Effects of Citric Acid Concentration and Activation Temperature on the Synthesis of Carbon Nanotubes

A series of Ni-La-Mg catalyst samples were prepared by citric acid complex method, and carbon nanotubes were synthesized by catalytic decomposition of CH4 on these catalysts. The effects of the citric acid concentration and the activation temperature on catalytic activity were investigated by CO adsorption, TEM and XRD techniques. The experimental results showed that the particle size of the catalysts prepared through gel auto-combustion varied with the concentration of citric acid. Therefore carbon nanotubes with different diameters were obtained correspondingly. The effect of activation temperature on the activity of catalyst was negligible from 500 to 700 ℃, but it became pronounced at lower or higher temperatures.

Effect of activation temperature on the properties of double layer capacitance of diatomite-templated carbon

1 Introduction In recent years porous carbons have been widely used in many fields such as energy storage(Mc Creery,2008;Liu et al,2009;Ho et al,2014;Yang et al,2015),adsorption,wastewater treatment,air purification

Effect of Sulfurization Temperature on Thioetherification Performance of Mo-Ni/Al_2O_3 Catalyst

The Mo modified Ni/Al_2O_3 catalysts were prepared and sulfided at different temperatures, and their catalytic activity for thioetherification of mercaptans and olefins(or dienes), hydrogenation of dienes and olefins in the thioetherification process using fluidized catalytic cracking(FCC) naphtha as the feedstock was investigated. In order to disclose the correlation between the physicochemical characteristics of catalysts and their catalytic activity, the surface structures and properties of the catalysts sulfided at different temperatures were characterized by the high resolution transmission electronic microscopy(HRTEM), X-ray photoelectron spectroscopy(XPS) and H2-temperature programmed reduction(H_2-TPR) technique. The results showed that an increase of sulfurization temperature not only could promote the sulfurization degree of active metals on the catalysts, but also could adjust the micro-morphology of active species. These changes could improve the catalytic performance of thioetherification, and hydrogenation of dienes and olefins. However, an excess sulfurization temperature was more easily to upgrade the ability of the catalyst for hydrogenation of olefins, which could lead to a decrease of the octane number of the product. It was also showed that a moderate sulfurization temperature not only could improve the catalytic performance of thioetherification and hydrogenation of dienes but also could control hydrogenation of olefins.

Enhanced cold active lipase production by metagenomic library recombinant clone CALIP3 with a step-wise temperature and dissolved oxygen level control strategy

A metagenomic library recombinant clone CAPL3, an Escherichia coli strain generated by transformed with metagenomic library from deep-sea sediments, can efficiently produce cold active lipase. The effects of both temperature and dissolved oxygen（DO） on cold active lipase production by batch culture of metagenomic library recombinant clone（CAPL3） from deep-sea sediment were investigated. First, a two-stage temperature control strategy was developed, in which the temperature was kept at 34 ℃ for the first 15 h, and then switched to30 ℃. The cold active lipase activity and productivity reached 315.2 U·ml^-1and 8.08 U·ml^-1·h^-1, respectively,increased by both 14.5% compared to the results obtained with temperature controlled at 30℃. In addition, different DO control modes were conducted, based on the data obtained from the different DO control strategies and analysis of kinetics parameters at different DO levels. A step-wise temperature and DO control strategy were developed to improve lipase production, i.e., temperature and DO level were controlled at 34℃, 30% during 0–15 h;30 ℃, 30% during 15–18 h, and 30 ℃, 20% during 18–39 h. With this strategy, the maximum lipase activity reached 354.6 U·ml^-1at 39 h, which was 28.8% higher than that achieved without temperature and DO control（275.3 U·ml^-1）.

Activation and pumping characteristics of Ti-Zr-V films deposited on narrow tubes

Non-evaporable getter(NEG)films are an integral part of many particle accelerators.These films provide conductance-free evenly distributed pumping,a low thermal outgassing rate,and a low photon-and electron-stimulated desorption.These characteristics make it an ideal solution for resolving the non-uniform pressure distribution in conductance-limited narrow vacuum tubes.In this study,ternary Ti-Zr-V films were deposited on Si substrates and Ag-Cu(Ag 0.085 wt%)tubes with an inner diameter of 22 mm.All Ti-Zr-V films were prepared from an alloy target using the same DC magnetron sputtering parameters.The compositions and corresponding chemical bonding states were analyzed by X-ray photoelectron spectroscopy after activation at different temperatures.The test particle Monte Carlo(TPMC)method was used to measure the sticking probability of the Ti-Zr-V film based on pressure readings during gas injection.The results indicate that activation commences at temperatures as low as 150℃and Ti~0,Zr~0,and V~0 exist on the surface after annealing at 180℃for 1 h.Ti-Zr-V films can be fully activated at 180℃for 24 h.The CO sticking probability reaches 0.15,with a pumping capacity of 1 monolayer.

Selective catalytic NO_x reduction on Antimony promoted V_2O_5-Sb/TiO_2 catalyst

Quantum chemical calculation was carried out to choose a promoter which can reduce the poisoning of V2O5/TiO2 catalysts by SO2. Several atoms were chosen as candidates and new catalysts were synthesized by impregnation method. The NOx conversion rate was measured at temperatures between 100 and 400 ℃ and poisoning effect was investigated. The most promising candidate promoter, Se, was excluded because of its high vapor pressure. On the other hand, Sb shows best promoting properties. Sb promoted catalyst reaches the maximum NOx conversion rate at 250 ℃. It also shows considerably enhanced resistance to poisoning of V2O5/TiO2 catalysts by SO2.

Research on Diamond Enhanced Tungsten Carbide Composite Button

At the present, the cutters used in button bits and rock bits are mainly cobalt tungsten carbide in our country. Because of its low abrasive resistance, the bit service life and drilling efficiency was very low when the hard and extremely hard formations were being drilled. Owing to its high abrasive resistance, the diamond composite material is widely used in drilling operations. However, its toughness against impact is too low to be used in percussion drilling, only can it be used in rotary drilling. In order to solve the problems encountered by DTH hammer in hard rock drilling, make bit life longer, increase rate of penetration and decrease drilling cost, a new type diamond enhanced tungsten carbide composite button with high abrasive resistance and high toughness against impact, which may be used in percussion drilling, has been developed. The key problems to make the button are to improve the thermal stability of diamond, to increase the welding strength between diamond and cemented tungsten carbide, and to lower the sintering temperature of tungsten carbide. All these problems have been solved effectively by pretreatment of diamond, low temperature activation hot-press sintering and high sintering pressure. (1) To plate tungsten on the surface of diamond. Diamond suffers easily from erosion in the environment of high temperature containing oxygen and iron family elements. There is very high energy between the interface of diamond and bonding metal and so the metallurgical bond can’t form at the interface between diamond and bond metal. This will lower greatly the bending strength and the toughness against impact of diamond enhanced tungsten carbide composite button. In order to improve thermal stability of diamond and increase the bonding strength of the interface between diamond and bond metal, to plate tungsten on the surface of diamond by vacuum vapor deposit is adopted. (2) To lower the sintering temperature by adding nickel, phosphorus and boron etc into conventional mixed powder. In general, the sintering temperature of cemented tungsten carbide is more than 1 350 ℃ in which diamond will suffer from serious heat erosion, so the sintering temperature must be lowered. To add nickel, phosphorus and boron etc into cobalt-base bond whose melting point is more than 1 350 ℃ will lower the sintering temperature to about 1 050 ℃. To add phosphorus can lower the temperature of liquid phase occurring and promote the densification of matrix alloy in advance because the co-crystallization temperature of Ni-P and Co-P is 880 ℃ and 1 020 ℃ respectively. The proper adding amount of nickel, phosphorus and boron etc is a key problem. To substitute nickel for partial cobalt can improve the toughness against impact of diamond enhanced tungsten carbide composite button and lower the sintering temperature. To add boron is helpful for sintering and improving the toughness against impact of diamond enhanced tungsten carbide composite button. (3) To increase the sintering press. Under the same sintering temperature, to improve the sintering press can improve the density and strength of sintering products. In this study to increase the sintering press 35 MPa in the usual conditions to 50～60 MPa in sintering diamond enhanced tungsten carbide button by adopting ceramic material as pressing rod has improved the sintering quality effectively. The properties of the button have been measured under lab conditions. The testing results show that its hardness is more than HRA86 and that its abrasiveness resistance is 100 times more than conventional cemented tungsten carbide, and its toughness against impact is more than 100J. All these data theoretically show that the button has very good mechanical properties that can meet the need of percussion drilling, and can solve the problems encountered with button bit of conventional cemented tungsten carbide.

Activity Enhancement of Vanadium Catalysts with Ultrasonic Preparation Process for the Oxidation of Sulfur Dioxide

The effect of ultrasonic cavitations on the activity of vanadium catalysts atlow temperatures for the oxidation of sulfur dioxide, in which refined carbonized mother liquor hadbeen added, was investigated. Twenty minutes were needed to produce obvious cavitations when thecatalyst raw material was treated in the 50 W ultrasonic generator. However, only 10 minutes wouldbe needed in a 150 W ultrasonic generator. The higher the temperature of the wet material, the lesstime was needed to produce cavitations, and the optimal temperature was 60℃. The water content inthe wet material mainly affected the quantity of cavitations. Ls-8 catalyst was prepared usingultrasonic. Its activity for conversion of SO_2 reached to 52.5% at 410℃ and 4.2% at 350℃. Thedifferential thermal analyses indicate that both endothermic peaks and exothermic peaks noticeablyshifted forward compared with Ls catalyst prepared without ultrasonic, and SEM results show auniform pore size distribution for Ls-8 catalyst.

Preparation of Cs-Rb-V series sulphuric acid catalyst

Cs Rb V series low temperature sulphuric acid catalyst was prepared for the first time by using carbonized mother liquor containing alkali metal salts. The results show that the conversion of SO 2 on catalyst prepared directly with carbonized mother liquor could reach to 24.8% at 410?℃. If n (Na)/ n (V) was adjusted properly, the conversion of SO 2 could be increased to 35.6% at 410?℃. Refined carbonized mother liquor could make the catalytic activity even higher at low temperature, the conversion of SO 2 could be increased to 36.65% at 410?℃. The catalyst was examined with differential thermal analysis. It was found that both endothermic peaks and exothermic peaks of catalyst shifted forward obviously and the catalyst possessed higher activity at low temperature.

Performance comparison of permafrost models in Wudaoliang Basin,Qinghai-Tibet Plateau,China

Knowledge of the spatial distribution of permafrost and the effects of climate on ground temperature are important for land use and infrastructure development on the Qinghai-Tibet Plateau(QTP). Different permafrost models have been developed to simulate the ground temperature and active layer thickness(ALT). In this study, Temperature at Top of Permafrost(TTOP) model, Kudryavtsev model and modified Stefan solution were evaluated against detailed field measurements at four distinct field sites in the Wudaoliang Basin to better understand the applicability of permafrost models. Field data from 2012 to 2014 showed that there were notable differences in observed ground temperatures and ALTs within and among the sites. The TTOP model is relatively simple, however, when driven by averaged input values, it produced more accurate permafrost surface temperature(Tps) than the Kudryavtsev model. The modified Stefan solution resulted in a satisfactory accuracy of 90%, which was better than the Kudryavtsev model for estimating ALTs. The modified Stefan solution had the potential of being applied to climate-change studies in the future. Furthermore, additional field investigations over longer periods focusing on hydrology, which has significant influence on permafrost thaw, are necessary. These efforts should employ advanced measurement techniques to obtain adequate and extensive local parameters that will help improve model accuracy.

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.

Dielectric Properties of Bi_4Ti_3O_(12) Ceramics by Impedance Spectroscopic Method

Various lead-free ceramics have been investigated in search for new high-temperature dielectrics. In particular, Bi_4Ti_3O_（12） is a type of ferroelectric ceramics, which is supposed to replace leadcontaining ceramics for its outstanding dielectric properties in the near future. Ferroelectric ceramics of Bi_4Ti_3O_（12） made by conventional mixed oxide route have been studied by impedance spectroscopy in a wide range of temperature. X-ray diffraction patterns show that Bi_4Ti_3O_（12） ceramics are a single-phase of ferroelectric Bi-layered perovskite structure whether it is calcined at 800 ℃ or after sintering production. This study focused on the effect of the grain size on the electric properties of BIT ceramics. The BIT ceramics with different grain sizes were prepared at different sintering temperatures. Grain becomes coarser with the sintering temperature increasing by 50 ℃, relative permittivity and dielectric loss also change a lot. When sintered at 1 100 ℃, r values peak can reach 205.40 at a frequency of 100 k Hz, the minimum dielectric losses of four different frequencies make no difference, all close to 0.027. The values of Ea range from 0.52 to 0.68 e V. The dielectric properties of the sample sintered at 1 100 ℃ are relatively better than those of the other samples by analyzing the relationship of the grain, the internal stresses, the homogeneity and the dielectric properties. SEM can better explain the results of the dielectric spectrum at different sintering temperatures. The results show that Bi_4Ti_3O_（12） ceramics are a kind of dielectrics. Thus, Bi_4Ti_3O_（12） can be used in high-temperature capacitors and microwave ceramics.

GaN-based violet laser diodes grown on free-standing GaN substrate

A violet laser diode （LD） structure is grown on a free-standing c-plane GaN substrate and 4 μm×800μm ridge waveguide LDs are fabricated. The electrical and the optical characteristics of LDs under different facet-coating and chip-mounting conditions are investigated under pulse mode operation. The active region temperatures of p-side up and p-side down mounted LDs are calculated with different injection currents. The calculated thermal resistances of p-side up and p-side down mounted LDs are 4.6 K/W and 3 K/W, respectively. The threshold current of the p-side down mounted LD is much lower than that of the p-side up mounted LD. The blue shift of the emission wavelength with increasing injection current is observed only for the LD with p-side down mounting configuration, due to the more efficient heat dissipation.

Screening Psychrophilic Fungi of Cellulose Degradation and Characteristic of Enzyme Production

A fungus（WR-C1） decomposed cellulose was isolated from a hypothermal litter layer using Congo red medium as the preliminary screening culture medium and then using a filter as the secondary screening medium at low temperature. The experiment showed that the weight loss rate of filter paper on the 15 th days could reach 30.69%. A morphologic and ITS gene sequence analysis suggested that CF-C1 was Cladosporium. We mainly studied the effects of culture time, inoculation amount, initial p H and different sources of carbon, nitrogen and inorganic salt on the cellulase production of strain WR-C1. Under optimum cultural condition, the highest value of WR-C1 enzyme production and filter paper enzyme were 3.27 U · m L～（-1） and 0.51 U · m L～（-1）.

Hydrogen Isotopes Recovery from Liquid Lithium under Dynamic Conditions

In the IFMIF （International Fusion Materials Irradiation Facility）, high-intensity deuteron ion beam is targeted at flowing liquid Li to produce neutron for long-time irradiation test of fusion materials. Radioactive tritium （T） will be produced as by-product of the D-Li reaction. Y hot trap is expected as an effective system to recover T from the liquid Li target loop. In the present study, absorption behavior of hydrogen isotopes in Y plates is experimentally and analytically investigated under stirring conditions of liquid Li. Experiments clarified that H2 absorption rates of solid Y immersed in Li are independent of the rotating rate in the range of 0 to 100 rpm and are in proportion to the inlet H2 concentration. The rate-determining step is H diffusion in Y. A mass-transfer coefficient is a useful parameter to correlate the overall H transfer from the gaseous phase through liquid Li to the solid Y plate. The effect of activation temperature on the overall performance when Y absorbs H is comparatively investigated. It is considered that heating at 673 K is effective to activate Y along with HF treatment.