This study evaluated the effect of potassium ferrate(PF)and low-temperature thermal hydrolysis co-pretreatment on the promotion of sludge hydrolysis process and the impact on acid production in the subsequent anaerobi...This study evaluated the effect of potassium ferrate(PF)and low-temperature thermal hydrolysis co-pretreatment on the promotion of sludge hydrolysis process and the impact on acid production in the subsequent anaerobic digestion process.The analytical investigations showed that co-pretreatment significantly facilitated the hydrolysis process of the sludge and contributed to the accumulation of short-chain fatty acids(SCFAs).The pretreatment conditions under the optimal leaching of organic matter from sludge were hydrothermal temperature of 75℃,hydrothermal treatment time of 12 h,and PF dosage of 0.25 g g^(−1)TSS(total suspended solids),according to the results of orthogonal experiments.By pretreatment under proper conditions,the removal rate of soluble chemical oxygen demand(SCOD)achieved 71.8%at the end of fermentation and the removal rate of total phosphorus(TP)was 69.1%.The maximum yield of SCFAs was 750.3 mg L^(−1),7.45 times greater than that of the blank group.Based on the analysis of the anaerobic digestion mechanism,it was indicated that the co-pretreatment could destroy the floc structure on the sludge surface and improve organic matter dissolving,resulting in more soluble organic substances for the acidification process.Furthermore,microbial community research revealed that the main cause of enhanced SCFAs generation was an increase in acidogenic bacteria and a reduction of methanogenic bacteria.展开更多
In the present study,flavor profiles of Chinese spiced beef in the cooking process were comparatively analyzed by electronic nose,gas chromatography–mass spectrometry(GC–MS)with a thermal desorption system(TDS),and ...In the present study,flavor profiles of Chinese spiced beef in the cooking process were comparatively analyzed by electronic nose,gas chromatography–mass spectrometry(GC–MS)with a thermal desorption system(TDS),and solid-phase microextraction(SPME).A total of 82 volatile compounds were identified,and 3-methyl-butanal,pentanal,hexanal,-xylene,heptanal,limonene,terpinene,octanal,linalool,4-terpinenol,-terpineol,and(E)-anethole were identified as the characteristic flavor compounds in Chinese spiced beef.Variation in the content of volatile components produced by different cooking processes was observed.In general,a cooking time of 4 h resulted in optimal flavor quality and stability.Results indicated that the electronic nose could profile and rapidly distinguish variation among different cooking time.The volatile profiling by TDS-GC–MS and responses from the electronic nose,in combination with multivariate statistical analysis,are a promising tool for control the cooking process of spiced beef.展开更多
The multi-walled carbon nanotubes(MWCNTs) studied in this work were synthesized by the catalytic chemical vapor deposition(CCVD) process, and were thermally annealed by the hot filament plasma enhanced(HF PE) method a...The multi-walled carbon nanotubes(MWCNTs) studied in this work were synthesized by the catalytic chemical vapor deposition(CCVD) process, and were thermally annealed by the hot filament plasma enhanced(HF PE) method at 550℃ for two hours.The x-ray absorption near edge structure(XANES) technique was used to investigate the adsorption and desorption phenomena of the MWCNTs at normal and grazing incidence angles.The adsorbates were found to have different sensitivities to the thermal annealing.The geometry of the incident beam consistently gave information about the adsorption and desorption phenomena.In addition, the adsorption of non-intrinsic potassium quantitatively affected the intrinsic adsorbates and contributed to increase the conductivity of the MWCNTs.The desorption of potassium was almost 70% greater after the thermal annealing.The potassium non-intrinsic adsorbates are from a physisorption mechanism whereas the intrinsic adsorbates result from chemisorption.展开更多
The nickel-base alloy is one of the leading candidate materials for generation IV nuclear reactor pressure vessel.To evaluate its stability of helium damage and retention,helium ions with different energy of 80 keV an...The nickel-base alloy is one of the leading candidate materials for generation IV nuclear reactor pressure vessel.To evaluate its stability of helium damage and retention,helium ions with different energy of 80 keV and 180 keV were introduced by ion implantation to a certain dose(peak displacement damage 1-10 dpa).Then thermal desorption spectroscopy(TDS)of helium atoms was performed to discuss the helium desorption characteristic and trapping sites.The desorption peaks shift to a lower temperature with increasing dpa for both 80 keV and 180 keV irradiation,reflecting the reduced diffusion activation energy and faster diffusion within the alloy.The main release peak temperature of 180 keV helium injection is relatively higher than that of 80 keV at the same influence,which is because the irradiation damage of 180 keV,helium formation and entrapment occur deeper.The broadening of the spectra corresponds to different helium trapping sites(He-vacancies,grain boundary)and desorption mechanisms(different Hen Vm size).The helium retention amount of 80 keV is lower than that of 180 keV,and a saturation limit associated with the irradiation of 80 keV has been reached.The relatively low helium retention proves the better resistance to helium bubbles formation and helium brittleness.展开更多
In this article,the binding forms of two lignite samples are determined by thermal desorption using a high-temperature furnace.Each mercury compound,such as HgCl2,has a specifc binding strength whose decomposition req...In this article,the binding forms of two lignite samples are determined by thermal desorption using a high-temperature furnace.Each mercury compound,such as HgCl2,has a specifc binding strength whose decomposition requires a certain thermal energy.Hence,the release of mercury from pure substances and lignite samples was analyzed in a high-temperature furnace.The released mercury is determined with a Mercury Vapor Monitor.The obtained characteristic temperature range and peak of the mercury release were compared between lignite samples and mercury pure substances.For the lignite samples investigated,the binding form of mercury was then identifed as Humic Acid.These organic compounds vaporize at lower temperatures.About half of the mercury bound in the lignite was already released at 350℃.Furthermore,the question arises whether mercury is already released during the grinding-drying process in the coal mill of a power plant.At two power plants,lignite samples were taken simultaneously at the feeder before entering the coal mill and at the dust line afterwards.The samples were analyzed for mercury concentration.The results show that up to one third of the mercury was already released in the coal mill.The vaporized mercury enters the combustion chamber detached from the lignite.The stated analysis methods and the results presented in this article contribute to the understanding of the mercury binding forms in lignite.It also shows the potential of thermal coal pretreatment as a favorable alternative mercury separation technology to others such as activated carbon dosing.展开更多
This paper describes for the first time the extraction followed by thermal desorption of polycyclic aromatic hydrocarbons (PAHs) spiked water samples in a microfluidic silicon device. Thanks to the integration into an...This paper describes for the first time the extraction followed by thermal desorption of polycyclic aromatic hydrocarbons (PAHs) spiked water samples in a microfluidic silicon device. Thanks to the integration into an original system composed of a micropump, microvalves, and an optimized thermal management, the entire protocol is automated and combines the extraction, the drying and the desorption in less than 25 min before sending the sample to a GC-FID system. Repeatable recovery yields have been determined for 1 μg/L spiked water samples and the analysis of PAHs in a natural water spiked sample has been demonstrated without loss of performance compared to purified water samples. Compared to other extraction techniques, this system has the advantage of reduced footprint, reduced energy consumption and no solvent use.展开更多
Group-V elemental nanofilms were predicted to exhibit interesting physical properties such as nontrivial topological properties due to their strong spin-orbit coupling,the quantum confinement,and surface effect.It was...Group-V elemental nanofilms were predicted to exhibit interesting physical properties such as nontrivial topological properties due to their strong spin-orbit coupling,the quantum confinement,and surface effect.It was reported that the ultrathin Sb nanofilms can undergo a series of topological transitions as a function of the film thickness h:from a topological semimetal(h>7.8 nm)to a topological insulator(7.8 nm>h>2.7 nm),then a quantum spin Hall(QSH)phase(2.7 nm>h>1.0 nm)and a topological trivial semiconductor(h<1.0 nm).Here,we report a comprehensive investigation on the epitaxial growth of Sb nanofilms on highly oriented pyrolytic graphite(HOPG)substrate and the controllable thermal desorption to achieve their specific thickness.The morphology,thickness,atomic structure,and thermal-strain effect of the Sb nanofilms were characterized by a combination study of scanning electron microscopy(SEM),atomic force microscopy(AFM),and scanning tunneling microscopy(STM).The realization of Sb nanofilms with specific thickness paves the way for the further exploring their thickness-dependent topological phase transitions and exotic physical properties.展开更多
The study is on the use of thermal desorption unit in the remediation of contaminated soils located at Beneku in Ndokwa East local government area of Delta state. This method uses heat to vaporize the contaminants, an...The study is on the use of thermal desorption unit in the remediation of contaminated soils located at Beneku in Ndokwa East local government area of Delta state. This method uses heat to vaporize the contaminants, and as such only works for volatile contaminants. Air quality samples around the thermal desorption Unit (TDU), used for the treatment of hydrocarbon impacted soils were taken at six (6) different sampling points (Stations). The sampling points were 100 m apart beginning from 0 m which was the closest to the TDU. The results showed that the mean values of SO<sub>2</sub> were 0.01 ppm for both the dry and wet seasons and it is within the FMEnv limit of 0.01. The mean concentration of NO<sub>2</sub> in the dry season was 0.25 μg/m<sup>3</sup> and in the wet season it was 0.18 μg/m<sup>3</sup>, which were above the FMEnv limit of 0.06 μg/m<sup>3</sup>. It is a strong oxidizing agent that reacts with air/water to form corrosive nitric acid, as well as toxic organic nitrates. The mean concentration of CO<sub>2</sub> recorded in the dry season was 11.52 ppm and that for the wet season was 10.53 ppm, which were slightly above the FMEnv limit of 10.00 ppm. The levels of SPM 2.5 recorded in the study show a concentration of 132.07 μg/m<sup>3</sup> in the dry season and 95.93 μg/m<sup>3</sup> in the wet season while those for SPM 10 had 102.17 μg/m<sup>3</sup> in the dry season and 91.33 μg/m<sup>3</sup> in the wet season. The level of the VOC recorded across the study area was significantly low (0.11 μg/m<sup>3</sup>). The mean H<sub>2</sub>S concentration recorded across the study area was low (0.01 μg/m<sup>3</sup>). Several health risks have been associated with SPM. Inhaling SPM affects respiratory and cardiovascular systems in both children and adults. Fine SPM (such as PM 2.5 particulate) can penetrate into the lungs and blood streams when inhaled, resulting to respiratory problems, heart attack, lung cancer and even death, while exposure to low levels of H<sub>2</sub>S can induce headaches as well as breathing difficulties in some asthmatic patients.展开更多
In this study,a composite powder capillary wick is prepared,manufactured by sintering copper powder and surface treated by low-temperature thermal oxidation.It is used to improve the performance of the capillary wick....In this study,a composite powder capillary wick is prepared,manufactured by sintering copper powder and surface treated by low-temperature thermal oxidation.It is used to improve the performance of the capillary wick.The forced flow method and infrared imaging method are used to test the permeability and capillary performance of the samples.The effects of different oxidation temperatures on the performance of capillary wick are investigated.The experimental results show that the wetting performance of the oxidized samples is significantly enhanced.With the increase of oxidation temperature,the permeability decreases.The capillary height and velocity of the thermally oxidized samples are significantly higher than those of the untreated capillary wick.However,the oxidation temperature needs to be adjusted to obtain the best capillary performance.The highest capillary performance is found at oxidation temperature of 300℃,with an increase of 46% compared to the untreated ones.Comparisons with other composite wicks show that the sample with an oxidation temperature of 300℃ has competitive capillary performance,making it a favorable alternative to two-phase heat transfer device.This study shows that combining low-temperature thermal oxidation technology with powder sintering is a convenient and effective method to improve the capillary performance of powder wicks.展开更多
Monitoring various internal parameters plays a core role in ensuring the safety of lithium-ion batteries in power supply applications.It also influences the sustainability effect and online state of charge prediction....Monitoring various internal parameters plays a core role in ensuring the safety of lithium-ion batteries in power supply applications.It also influences the sustainability effect and online state of charge prediction.An improved multiple feature-electrochemical thermal coupling modeling method is proposed considering low-temperature performance degradation for the complete characteristic expression of multi-dimensional information.This is to obtain the parameter influence mechanism with a multi-variable coupling relationship.An optimized decoupled deviation strategy is constructed for accurate state of charge prediction with real-time correction of time-varying current and temperature effects.The innovative decoupling method is combined with the functional relationships of state of charge and open-circuit voltage to capture energy management ef-fectively.Then,an adaptive equivalent-prediction model is constructed using the state-space equation and iterative feedback correction,making the proposed model adaptive to fractional calculation.The maximum state of charge estimation errors of the proposed method are 4.57% and 0.223% under the Beijing bus dynamic stress test and dynamic stress test conditions,respectively.The improved multiple feature-electrochemical thermal coupling modeling realizes the effective correction of the current and temperature variations with noise influencing coefficient,and provides an efficient state of charge prediction method adaptive to complex conditions.展开更多
In this paper,diamond/CuCr and diamond/CuB composites were prepared using the pressure infiltration method.The physical property measurement system(PPMS)was adopted to evaluate the thermal conductivity of diamond/Cu a...In this paper,diamond/CuCr and diamond/CuB composites were prepared using the pressure infiltration method.The physical property measurement system(PPMS)was adopted to evaluate the thermal conductivity of diamond/Cu and MoCu composites within the range of100–350 K,and a scanning electron microscope(SEM)was utilized to analyze the microstructure and fracture appearance of the materials.The research indicates that the thermal conductivity of diamond/Cu composite within the range of100–350 K is 2.5–3.0 times that of the existing MoCu material,and the low-temperature thermal conductivity of diamond/Cu composite presents an exponential relationship with the temperature.If B element was added to a Cu matrix and a low-temperature binder was used for prefabricated elements,favorable interfacial adhesion,relatively high interfacial thermal conductivity,and favorable low-temperature heat conduction characteristics would be apparent.展开更多
Light crude oil from the lower member of the Paleogene Xiaganchaigou Formation of Gaskule in Qinghai Oilfield was selected to carry out thermal kinetic analysis experiments and calculate the activation energy during t...Light crude oil from the lower member of the Paleogene Xiaganchaigou Formation of Gaskule in Qinghai Oilfield was selected to carry out thermal kinetic analysis experiments and calculate the activation energy during the oil oxidation process.The oxidation process of crude oi l in porous medium was modeled by crude oil static oxidation experiment,and the component changes of crude oil before and after low-temperature oxidation were compared through Fourier transform ion cy-clotron resonance mass spectrometry and gas chromatography;the dynamic displacement experiment of oxygen-reduced air was combined with NMR technology to analyze the oil recovery degree of oxygen-reduced air flooding.The whole process of crude oil oxidation can be divided into four stages:light hydrocarbon volatilization,low-temperature oxidation,fuel deposition,and high temperature oxidation;the high temperature oxidation stage needs the highest activation energy,followed by the fuel deposition stage,and the low-temperature oxidation stage needs the lowest activation energy;the concentration of oxygen in the reaction is negatively correlated with the activation energy required for the reaction;the higher the oxygen concentration,the lower the average activation energy required for oxidation reaction is;the low-temperature oxidation reaction between crude oil and air generates a large amount of heat and CO,CO_(2) and CH4,forming flue gas drive in the reservoir,which has certain effects of mixing phases,reducing viscosity,lowering interfacial tension and promoting expansion of crude oil,and thus helps enhance the oil recovery rate.Under suitable reservoir temperature condition,the degree of recovery of oxygen-reduced air flooding is higher than that of nitrogen flooding for all scales of pore throat,and the air/oxygen-reduced air flooding de-velopment should be preferred.展开更多
A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-...A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-temperature photoluminescence spectra of fine-grained obliquely deposited films. Doping film with In impurity leads to quenching of the doublet band, while further thermal treatment causes activation of the intrinsic band, the half-width and the blue shift of the red edge of which correlates with the maximum value of anomalously high photovoltage generated by the film.展开更多
We investigated synthesis and characterization of melamine-urea-formaldehyde(MUF) microcapsules containing n-alkane mixture as phase change core material for thermal energy storage and low-temperature protection. Th...We investigated synthesis and characterization of melamine-urea-formaldehyde(MUF) microcapsules containing n-alkane mixture as phase change core material for thermal energy storage and low-temperature protection. The phase change microcapsules(microPCMs) were prepared by an in situ polymerization using sodium dodecyl sulfate(SDS) and polyvinyl alcohol(PVA) as emulsifiers. Surface morphology, particle size, chemical structure, and thermal properties of microPCMs were, respectively, characterized by using scanning electron microscopy(SEM), field emission scanning electron microscopy(FESEM), Fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC), and thermal gravimetric analysis(TGA). Low-temperature resistance performances were measured at-15,-30,-45, and-60 ℃ after microPCMs were coated on a cotton fabric by foaming technology. The results showed that spherical microPCMs had 4.4 μm diameter and 100 nm wall thickness. The melting and freezing temperatures and the latent heats of the microPCMs were determined as 28.9 and 29.6 ℃ as well as 110.0 and 115.7 J/g, respectively. Encapsulation of n-alkane mixture achieved 84.9 %. TGA analysis indicated that the microPCMs had good chemical stability below 250 ℃. The results showed that the microencapsulated n-alkane mixture had good energy storage potential. After the addition of 10 % microPCMs, low-temperature resistance duration was prolonged by 126.9%, 145.5%, 128.6%, and 87.5% in environment of-15,-30,-45 and-60 ℃, respectively as compared to pure fabric. Based on the results, phase change microcapsule plays an effective role in lowtemperature protection field for the human body.展开更多
The low-temperature heat capacities are studied for antiperovskite compounds AX M_3(A = Al, Ga, Cu, Ag, Sn, X = C,N, M = Mn, Fe, Co). A large peak in(C- γ T)/T^3 versus T is observed for each of a total of 18 com...The low-temperature heat capacities are studied for antiperovskite compounds AX M_3(A = Al, Ga, Cu, Ag, Sn, X = C,N, M = Mn, Fe, Co). A large peak in(C- γ T)/T^3 versus T is observed for each of a total of 18 compounds investigated,indicating an existence of low-energy phonon mode unexpected by Debye T^3 law. Such a peak is insensitive to the external magnetic field up to 80 k Oe(1 Oe = 79.5775 A·m-1). For compounds with smaller lattice constant, the peak shifts towards higher temperatures with a reduction of peak height. This abnormal peak in(C- γ T)/T^3 versus T of antiperovskite compound may result from the strongly dispersive acoustic branch due to the heavier A atoms and the optical-like mode from the dynamic rotation of X M_6 octahedron. Such a low-energy phonon mode may not contribute negatively to the normal thermal expansion in AX M_3 compounds, while it is usually concomitant with negative thermal expansion in open-structure material(e.g., ZrW_2O_8, Sc F_3).展开更多
基金supported by the National Natural Science Foundation of China(No.41276067)the Air Liquide(China)R&D Co.,Ltd.(No.20200216).
文摘This study evaluated the effect of potassium ferrate(PF)and low-temperature thermal hydrolysis co-pretreatment on the promotion of sludge hydrolysis process and the impact on acid production in the subsequent anaerobic digestion process.The analytical investigations showed that co-pretreatment significantly facilitated the hydrolysis process of the sludge and contributed to the accumulation of short-chain fatty acids(SCFAs).The pretreatment conditions under the optimal leaching of organic matter from sludge were hydrothermal temperature of 75℃,hydrothermal treatment time of 12 h,and PF dosage of 0.25 g g^(−1)TSS(total suspended solids),according to the results of orthogonal experiments.By pretreatment under proper conditions,the removal rate of soluble chemical oxygen demand(SCOD)achieved 71.8%at the end of fermentation and the removal rate of total phosphorus(TP)was 69.1%.The maximum yield of SCFAs was 750.3 mg L^(−1),7.45 times greater than that of the blank group.Based on the analysis of the anaerobic digestion mechanism,it was indicated that the co-pretreatment could destroy the floc structure on the sludge surface and improve organic matter dissolving,resulting in more soluble organic substances for the acidification process.Furthermore,microbial community research revealed that the main cause of enhanced SCFAs generation was an increase in acidogenic bacteria and a reduction of methanogenic bacteria.
基金This work was part of the project“Research and Development of Nutrition and Health Processing for Halal Beef and Muttons”,and was financially supported by Ningxia Hui Autonomous Region Technology R&D Support Program as well as the“13th Five-Year Plan”(No.2016YFD0400703)of National Key Research and Development Program of China.
文摘In the present study,flavor profiles of Chinese spiced beef in the cooking process were comparatively analyzed by electronic nose,gas chromatography–mass spectrometry(GC–MS)with a thermal desorption system(TDS),and solid-phase microextraction(SPME).A total of 82 volatile compounds were identified,and 3-methyl-butanal,pentanal,hexanal,-xylene,heptanal,limonene,terpinene,octanal,linalool,4-terpinenol,-terpineol,and(E)-anethole were identified as the characteristic flavor compounds in Chinese spiced beef.Variation in the content of volatile components produced by different cooking processes was observed.In general,a cooking time of 4 h resulted in optimal flavor quality and stability.Results indicated that the electronic nose could profile and rapidly distinguish variation among different cooking time.The volatile profiling by TDS-GC–MS and responses from the electronic nose,in combination with multivariate statistical analysis,are a promising tool for control the cooking process of spiced beef.
文摘The multi-walled carbon nanotubes(MWCNTs) studied in this work were synthesized by the catalytic chemical vapor deposition(CCVD) process, and were thermally annealed by the hot filament plasma enhanced(HF PE) method at 550℃ for two hours.The x-ray absorption near edge structure(XANES) technique was used to investigate the adsorption and desorption phenomena of the MWCNTs at normal and grazing incidence angles.The adsorbates were found to have different sensitivities to the thermal annealing.The geometry of the incident beam consistently gave information about the adsorption and desorption phenomena.In addition, the adsorption of non-intrinsic potassium quantitatively affected the intrinsic adsorbates and contributed to increase the conductivity of the MWCNTs.The desorption of potassium was almost 70% greater after the thermal annealing.The potassium non-intrinsic adsorbates are from a physisorption mechanism whereas the intrinsic adsorbates result from chemisorption.
基金Project supported by Special Funds for Fundamental Research Funds for Central Universities,China(Grant Nos.2018 NTST29 and 2018 NTST04)the National Natural Science Foundation of China(Grant No.61176003)+1 种基金Chinese Postdoctoral Science Foundation(Grant No.2019M650524)Guangdong Province Key Area R&D Program,China(Grant No.2019B090909002)。
文摘The nickel-base alloy is one of the leading candidate materials for generation IV nuclear reactor pressure vessel.To evaluate its stability of helium damage and retention,helium ions with different energy of 80 keV and 180 keV were introduced by ion implantation to a certain dose(peak displacement damage 1-10 dpa).Then thermal desorption spectroscopy(TDS)of helium atoms was performed to discuss the helium desorption characteristic and trapping sites.The desorption peaks shift to a lower temperature with increasing dpa for both 80 keV and 180 keV irradiation,reflecting the reduced diffusion activation energy and faster diffusion within the alloy.The main release peak temperature of 180 keV helium injection is relatively higher than that of 80 keV at the same influence,which is because the irradiation damage of 180 keV,helium formation and entrapment occur deeper.The broadening of the spectra corresponds to different helium trapping sites(He-vacancies,grain boundary)and desorption mechanisms(different Hen Vm size).The helium retention amount of 80 keV is lower than that of 180 keV,and a saturation limit associated with the irradiation of 80 keV has been reached.The relatively low helium retention proves the better resistance to helium bubbles formation and helium brittleness.
文摘In this article,the binding forms of two lignite samples are determined by thermal desorption using a high-temperature furnace.Each mercury compound,such as HgCl2,has a specifc binding strength whose decomposition requires a certain thermal energy.Hence,the release of mercury from pure substances and lignite samples was analyzed in a high-temperature furnace.The released mercury is determined with a Mercury Vapor Monitor.The obtained characteristic temperature range and peak of the mercury release were compared between lignite samples and mercury pure substances.For the lignite samples investigated,the binding form of mercury was then identifed as Humic Acid.These organic compounds vaporize at lower temperatures.About half of the mercury bound in the lignite was already released at 350℃.Furthermore,the question arises whether mercury is already released during the grinding-drying process in the coal mill of a power plant.At two power plants,lignite samples were taken simultaneously at the feeder before entering the coal mill and at the dust line afterwards.The samples were analyzed for mercury concentration.The results show that up to one third of the mercury was already released in the coal mill.The vaporized mercury enters the combustion chamber detached from the lignite.The stated analysis methods and the results presented in this article contribute to the understanding of the mercury binding forms in lignite.It also shows the potential of thermal coal pretreatment as a favorable alternative mercury separation technology to others such as activated carbon dosing.
文摘This paper describes for the first time the extraction followed by thermal desorption of polycyclic aromatic hydrocarbons (PAHs) spiked water samples in a microfluidic silicon device. Thanks to the integration into an original system composed of a micropump, microvalves, and an optimized thermal management, the entire protocol is automated and combines the extraction, the drying and the desorption in less than 25 min before sending the sample to a GC-FID system. Repeatable recovery yields have been determined for 1 μg/L spiked water samples and the analysis of PAHs in a natural water spiked sample has been demonstrated without loss of performance compared to purified water samples. Compared to other extraction techniques, this system has the advantage of reduced footprint, reduced energy consumption and no solvent use.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21622304,61674045,11604063,and 61911540074)the National Key Research and Development Program of China(Grant No.2016YFA0200700)+2 种基金the Strategic Priority Research Program and Key Research Program of Frontier Sciences and Instrument Developing Project(Chinese Academy of Sciences,CAS)(Grant Nos.XDB30000000,QYZDB-SSW-SYS031,and YZ201418)Z.H.Cheng was supported by Distinguished Technical Talents Project and Youth Innovation Promotion Association CAS,the Fundamental Research Funds for the Central Universities,Chinathe Research Funds of Renmin University of China(Grant No.18XNLG01).
文摘Group-V elemental nanofilms were predicted to exhibit interesting physical properties such as nontrivial topological properties due to their strong spin-orbit coupling,the quantum confinement,and surface effect.It was reported that the ultrathin Sb nanofilms can undergo a series of topological transitions as a function of the film thickness h:from a topological semimetal(h>7.8 nm)to a topological insulator(7.8 nm>h>2.7 nm),then a quantum spin Hall(QSH)phase(2.7 nm>h>1.0 nm)and a topological trivial semiconductor(h<1.0 nm).Here,we report a comprehensive investigation on the epitaxial growth of Sb nanofilms on highly oriented pyrolytic graphite(HOPG)substrate and the controllable thermal desorption to achieve their specific thickness.The morphology,thickness,atomic structure,and thermal-strain effect of the Sb nanofilms were characterized by a combination study of scanning electron microscopy(SEM),atomic force microscopy(AFM),and scanning tunneling microscopy(STM).The realization of Sb nanofilms with specific thickness paves the way for the further exploring their thickness-dependent topological phase transitions and exotic physical properties.
文摘The study is on the use of thermal desorption unit in the remediation of contaminated soils located at Beneku in Ndokwa East local government area of Delta state. This method uses heat to vaporize the contaminants, and as such only works for volatile contaminants. Air quality samples around the thermal desorption Unit (TDU), used for the treatment of hydrocarbon impacted soils were taken at six (6) different sampling points (Stations). The sampling points were 100 m apart beginning from 0 m which was the closest to the TDU. The results showed that the mean values of SO<sub>2</sub> were 0.01 ppm for both the dry and wet seasons and it is within the FMEnv limit of 0.01. The mean concentration of NO<sub>2</sub> in the dry season was 0.25 μg/m<sup>3</sup> and in the wet season it was 0.18 μg/m<sup>3</sup>, which were above the FMEnv limit of 0.06 μg/m<sup>3</sup>. It is a strong oxidizing agent that reacts with air/water to form corrosive nitric acid, as well as toxic organic nitrates. The mean concentration of CO<sub>2</sub> recorded in the dry season was 11.52 ppm and that for the wet season was 10.53 ppm, which were slightly above the FMEnv limit of 10.00 ppm. The levels of SPM 2.5 recorded in the study show a concentration of 132.07 μg/m<sup>3</sup> in the dry season and 95.93 μg/m<sup>3</sup> in the wet season while those for SPM 10 had 102.17 μg/m<sup>3</sup> in the dry season and 91.33 μg/m<sup>3</sup> in the wet season. The level of the VOC recorded across the study area was significantly low (0.11 μg/m<sup>3</sup>). The mean H<sub>2</sub>S concentration recorded across the study area was low (0.01 μg/m<sup>3</sup>). Several health risks have been associated with SPM. Inhaling SPM affects respiratory and cardiovascular systems in both children and adults. Fine SPM (such as PM 2.5 particulate) can penetrate into the lungs and blood streams when inhaled, resulting to respiratory problems, heart attack, lung cancer and even death, while exposure to low levels of H<sub>2</sub>S can induce headaches as well as breathing difficulties in some asthmatic patients.
基金financial support for this research from the National Natural Science Foundation of China (52006040 and 51876044)the Natural Science Foundation of Guangdong Province(2019B090905005)the International Science and Technology Projects of Huangpu District of Guangzhou City(2020GH08)。
文摘In this study,a composite powder capillary wick is prepared,manufactured by sintering copper powder and surface treated by low-temperature thermal oxidation.It is used to improve the performance of the capillary wick.The forced flow method and infrared imaging method are used to test the permeability and capillary performance of the samples.The effects of different oxidation temperatures on the performance of capillary wick are investigated.The experimental results show that the wetting performance of the oxidized samples is significantly enhanced.With the increase of oxidation temperature,the permeability decreases.The capillary height and velocity of the thermally oxidized samples are significantly higher than those of the untreated capillary wick.However,the oxidation temperature needs to be adjusted to obtain the best capillary performance.The highest capillary performance is found at oxidation temperature of 300℃,with an increase of 46% compared to the untreated ones.Comparisons with other composite wicks show that the sample with an oxidation temperature of 300℃ has competitive capillary performance,making it a favorable alternative to two-phase heat transfer device.This study shows that combining low-temperature thermal oxidation technology with powder sintering is a convenient and effective method to improve the capillary performance of powder wicks.
基金supported by the National Natural Science Foundation of China(No.62173281)the Natural Science Foundation of Sichuan Province(No.23ZDYF0734 and No.2023NSFSC1436)the Fund of Robot Technology Used for Special Environment Key Laboratory of Sichuan Province(No.18kftk03).
文摘Monitoring various internal parameters plays a core role in ensuring the safety of lithium-ion batteries in power supply applications.It also influences the sustainability effect and online state of charge prediction.An improved multiple feature-electrochemical thermal coupling modeling method is proposed considering low-temperature performance degradation for the complete characteristic expression of multi-dimensional information.This is to obtain the parameter influence mechanism with a multi-variable coupling relationship.An optimized decoupled deviation strategy is constructed for accurate state of charge prediction with real-time correction of time-varying current and temperature effects.The innovative decoupling method is combined with the functional relationships of state of charge and open-circuit voltage to capture energy management ef-fectively.Then,an adaptive equivalent-prediction model is constructed using the state-space equation and iterative feedback correction,making the proposed model adaptive to fractional calculation.The maximum state of charge estimation errors of the proposed method are 4.57% and 0.223% under the Beijing bus dynamic stress test and dynamic stress test conditions,respectively.The improved multiple feature-electrochemical thermal coupling modeling realizes the effective correction of the current and temperature variations with noise influencing coefficient,and provides an efficient state of charge prediction method adaptive to complex conditions.
基金supported by the National Natural Science Foundation of China (No. 50971020)
文摘In this paper,diamond/CuCr and diamond/CuB composites were prepared using the pressure infiltration method.The physical property measurement system(PPMS)was adopted to evaluate the thermal conductivity of diamond/Cu and MoCu composites within the range of100–350 K,and a scanning electron microscope(SEM)was utilized to analyze the microstructure and fracture appearance of the materials.The research indicates that the thermal conductivity of diamond/Cu composite within the range of100–350 K is 2.5–3.0 times that of the existing MoCu material,and the low-temperature thermal conductivity of diamond/Cu composite presents an exponential relationship with the temperature.If B element was added to a Cu matrix and a low-temperature binder was used for prefabricated elements,favorable interfacial adhesion,relatively high interfacial thermal conductivity,and favorable low-temperature heat conduction characteristics would be apparent.
文摘Light crude oil from the lower member of the Paleogene Xiaganchaigou Formation of Gaskule in Qinghai Oilfield was selected to carry out thermal kinetic analysis experiments and calculate the activation energy during the oil oxidation process.The oxidation process of crude oi l in porous medium was modeled by crude oil static oxidation experiment,and the component changes of crude oil before and after low-temperature oxidation were compared through Fourier transform ion cy-clotron resonance mass spectrometry and gas chromatography;the dynamic displacement experiment of oxygen-reduced air was combined with NMR technology to analyze the oil recovery degree of oxygen-reduced air flooding.The whole process of crude oil oxidation can be divided into four stages:light hydrocarbon volatilization,low-temperature oxidation,fuel deposition,and high temperature oxidation;the high temperature oxidation stage needs the highest activation energy,followed by the fuel deposition stage,and the low-temperature oxidation stage needs the lowest activation energy;the concentration of oxygen in the reaction is negatively correlated with the activation energy required for the reaction;the higher the oxygen concentration,the lower the average activation energy required for oxidation reaction is;the low-temperature oxidation reaction between crude oil and air generates a large amount of heat and CO,CO_(2) and CH4,forming flue gas drive in the reservoir,which has certain effects of mixing phases,reducing viscosity,lowering interfacial tension and promoting expansion of crude oil,and thus helps enhance the oil recovery rate.Under suitable reservoir temperature condition,the degree of recovery of oxygen-reduced air flooding is higher than that of nitrogen flooding for all scales of pore throat,and the air/oxygen-reduced air flooding de-velopment should be preferred.
文摘A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-temperature photoluminescence spectra of fine-grained obliquely deposited films. Doping film with In impurity leads to quenching of the doublet band, while further thermal treatment causes activation of the intrinsic band, the half-width and the blue shift of the red edge of which correlates with the maximum value of anomalously high photovoltage generated by the film.
基金Funded by Tianjin Research Program of Application Foundation and Advanced Technology(No.15JCZDJC38400)the National Natural Science Foundation of China(Nos.51303131 and 51303128)
文摘We investigated synthesis and characterization of melamine-urea-formaldehyde(MUF) microcapsules containing n-alkane mixture as phase change core material for thermal energy storage and low-temperature protection. The phase change microcapsules(microPCMs) were prepared by an in situ polymerization using sodium dodecyl sulfate(SDS) and polyvinyl alcohol(PVA) as emulsifiers. Surface morphology, particle size, chemical structure, and thermal properties of microPCMs were, respectively, characterized by using scanning electron microscopy(SEM), field emission scanning electron microscopy(FESEM), Fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC), and thermal gravimetric analysis(TGA). Low-temperature resistance performances were measured at-15,-30,-45, and-60 ℃ after microPCMs were coated on a cotton fabric by foaming technology. The results showed that spherical microPCMs had 4.4 μm diameter and 100 nm wall thickness. The melting and freezing temperatures and the latent heats of the microPCMs were determined as 28.9 and 29.6 ℃ as well as 110.0 and 115.7 J/g, respectively. Encapsulation of n-alkane mixture achieved 84.9 %. TGA analysis indicated that the microPCMs had good chemical stability below 250 ℃. The results showed that the microencapsulated n-alkane mixture had good energy storage potential. After the addition of 10 % microPCMs, low-temperature resistance duration was prolonged by 126.9%, 145.5%, 128.6%, and 87.5% in environment of-15,-30,-45 and-60 ℃, respectively as compared to pure fabric. Based on the results, phase change microcapsule plays an effective role in lowtemperature protection field for the human body.
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2011CBA00111)the National Natural Science Foundation of China(Grant Nos.51322105,U1632158,51301165,and 51301167)
文摘The low-temperature heat capacities are studied for antiperovskite compounds AX M_3(A = Al, Ga, Cu, Ag, Sn, X = C,N, M = Mn, Fe, Co). A large peak in(C- γ T)/T^3 versus T is observed for each of a total of 18 compounds investigated,indicating an existence of low-energy phonon mode unexpected by Debye T^3 law. Such a peak is insensitive to the external magnetic field up to 80 k Oe(1 Oe = 79.5775 A·m-1). For compounds with smaller lattice constant, the peak shifts towards higher temperatures with a reduction of peak height. This abnormal peak in(C- γ T)/T^3 versus T of antiperovskite compound may result from the strongly dispersive acoustic branch due to the heavier A atoms and the optical-like mode from the dynamic rotation of X M_6 octahedron. Such a low-energy phonon mode may not contribute negatively to the normal thermal expansion in AX M_3 compounds, while it is usually concomitant with negative thermal expansion in open-structure material(e.g., ZrW_2O_8, Sc F_3).