Precise high-temperature weather forecasts are essential, as heatwaves are increasing in frequency under the ongoing climate change. Land-surface schemes have been demonstrated to be crucial to numerical weather predi...Precise high-temperature weather forecasts are essential, as heatwaves are increasing in frequency under the ongoing climate change. Land-surface schemes have been demonstrated to be crucial to numerical weather predictions.However, few studies have explored the impact of land surface schemes on short-range high-temperature weather forecasts via operational numerical weather prediction models. To evaluate the impact of the soil thermal process on high-temperature weather forecasts, we coupled the soil thermal process of the state-of-the-art Common Land Model(CoLM) with the South China operational numerical weather prediction model(CMA-TRAMS) and compared the coupled model with the original CMA-TRAMS, which incorporated the Simplified Model for land Surface(SMS). Contrast experiments based on two versions of CMA-TRAMS were conducted for the year 2022 when persistent extreme heatwaves were observed in Central-East China. The results are as follows:(1) Short-range high-temperature weather forecasts were sensitive to soil thermal process schemes. The original CMA-TRAMS clearly underestimated the summertime near-surface air temperature(T2m) over almost all areas of China, whereas the CoLM led to a reduction of the negative biases by approximately 0.5°C.(2) The more accurate initial soil temperatures and the deeper soil structure used in the CoLM test contributed to actual predictions of soil heat flux, soil temperature, and T2m. Nevertheless, the SMS test failed to capture upward heat transport from deeper to shallower soil layers at night due to the shallow soil structure and lower accuracy of the bottom and initial soil temperatures.(3) Higher soil temperatures resulted in increased near-surface moisture and cloud cover in the CoLM test, which led to the warmer soil and further mitigated the cold biases of T2m through reduced longwave and shortwave radiation losses at the land surface.展开更多
The direct conversion of methane using a dielectric barrier discharge has been experimentally studied. Experiments with different values of flow rates and discharge voltages have been performed to investigate the effe...The direct conversion of methane using a dielectric barrier discharge has been experimentally studied. Experiments with different values of flow rates and discharge voltages have been performed to investigate the effects on the conversion and reaction products both qualitatively and quantitatively. Experimental results indicate that the maximum conversion of methane has been 80% at an input flow rate of 5 ml/min and a discharge voltage of 4 kV. Experimental results also show that the optimum condition has occurred at a high discharge voltage and higher input flow rate. In terms of product distribution, a higher flow rate or shorter residence time can increase the selectivity for higher hydrocarbons. No hydrocarbon product was detected using the thermal method, except hydrogen and carbon. Increasing selectivity for ethane was found when Pt and Ru catalysts presented in the plasma reaction. Hydrogenation of acetylene in the catalyst surface could have been the reason for this phenomenon as the selectivity for acetylene in the products was decreasing.展开更多
The precipitation evolutions of Mg-Al-Zn alloys play essential roles in their mechanical properties,corrosion performance,formability,plastic deformation mechanisms and texture development.In the present work,the prec...The precipitation evolutions of Mg-Al-Zn alloys play essential roles in their mechanical properties,corrosion performance,formability,plastic deformation mechanisms and texture development.In the present work,the precipitation evolutions of AZ80 magnesium alloy during both non-isothermal and isothermal processes were unraveled by utilizing in situ electrical resistivity monitoring,hardness testing,differential scanning calorimetry and microstructural characterization.The results showed that discontinuous precipitation(DP)and continuous precipitation(CP)occurred competitively during non-isothermal and isothermal processes.The precipitation of dominantβ-Mg17 Al12 phase during non-isothermal processes was highly dependent on the thermal history.During isothermal processes,the precipitation behavior of AZ80 magnesium alloy could be considered as the functions of holding temperature and time.At lower temperatures,massive DP and CP were gradually formed to equally strengthen the alloy.At higher temperatures,the Ostwald coarsening was characterized in the later stages and indicated to slightly soften the alloy.Isothermal time-temperature-precipitation curves and quantitative precipitate evolution were estimated to unravel precipitation characteristics and their strengthening functions.展开更多
Qingke(highland hull-less barley)is a grain replete with substantial nutrients and bioactive ingredients.In this study,we evaluated the effects of boiling(BO),steaming(ST),microwave baking(MB),far-infrared baking(FB),...Qingke(highland hull-less barley)is a grain replete with substantial nutrients and bioactive ingredients.In this study,we evaluated the effects of boiling(BO),steaming(ST),microwave baking(MB),far-infrared baking(FB),steam explosion(SE),and deep frying(DF)on bioactive components,phenolic compounds,and antioxidant activities of Qingke compared with the effects of traditional roast(TR).Results showed that the soluble dietary fiber,beta-glucan and water-extractable pentosans of Qingke in dry heat processes of TR,SE,MB and FB had a higher content compared with other thermal methods and had a better antioxidant activity of hydroxyl radical scavenging and a better reduction capacity,while those in wet heat processes of BO and ST had a better antioxidant activity of ABTS radical scavenging and a better Fe^(2+) chelating ability.DF-and SE-Qingke had a higher content of tocopherol,phenolic,and flavonoid.Overall,6 free phenolic compounds and 12 bound phenolic compounds of Qingke were identified,and free phenolic compounds suffered more damage during thermal processing.Principal component analysis showed that SE had more advantages in retaining and improving the main biological active ingredients of Qingke,and it may be the best method for treating Qingke.展开更多
Engineering point defects such as metal and oxygen vacancies play a crucial role in manipulating the electrical,optical,and catalytic properties of oxide semiconductors for solar water splitting.Herein,we synthesized ...Engineering point defects such as metal and oxygen vacancies play a crucial role in manipulating the electrical,optical,and catalytic properties of oxide semiconductors for solar water splitting.Herein,we synthesized nanoporous CuBi_(2)O_(4)(np-CBO)photocathodes and engineered their surface point defects via rapid thermal processing(RTP)in controlled atmospheres(O_(2),N_(2),and vacuum).We found that the O_(2)-RTP treatment of np-CBO increased the charge carrier density effectively without hampering the nanoporous morphology,which was attributed to the formation of copper vacancies(VCu).Further analyses revealed that the amounts of oxygen vacancies(Vo)and Cu^(1+)were reduced simultaneously,and the relative electrochemical active surface area increased after the O_(2)-RTP treatment.Notably,the point defects(VC_(u),Cu^(1+),and Vo)regulated np-CBO achieved a superb water-splitting photocurrent density of-1.81 m A cm^(-2) under simulated sunlight illumination,which is attributed to the enhanced charge transport and transfer properties resulting from the regulated surface point defects.Finally,the reversibility of the formation of the point defects was checked by sequential RTP treatments(O_(2)-N_(2)-O_(2)-N_(2)),demonstrating the strong dependence of photocurrent response on the RTP cycles.Conclusively,the surface point defect engineering via RTP treatment in a controlled atmosphere is a rapid and facile strategy to promote charge transport and transfer properties of photoelectrodes for efficient solar water-splitting.展开更多
Wheat allergy has become a serious health threat worldwide and its prevalence has increased alarmingly in the past few years.Factors such as food matrix and food processing may alter the structure of wheat proteins,an...Wheat allergy has become a serious health threat worldwide and its prevalence has increased alarmingly in the past few years.Factors such as food matrix and food processing may alter the structure of wheat proteins,and hence affect its allergenic properties.However,few reports have focused on the influence of Chinese traditional starter fermentation on wheat allergy.In this study,5 starters from different regions of China were used for fermentation,and protein characteristics were monitored by sodium dodecyl sulfate polyacrylamide gel electropheresis,and immunoreactivity analyzed by immunoassay with allergenic serum was obtained from New Zealand white rabbits.The allergenicity of steamed and baked matrices was also evaluated.The results showed that the allergenicity of wheat dough was basically increased at the beginning and then decreased during fermentation,but specific trends depend on different starters.With the progress of fermentation,especially as pH value decreased to 3.0-4.0,the allergenicity decreased significantly.Baking and steaming can reduce the allergenicity of wheat matrix,but fermentation is not a key factor affecting the allergenic activity of proteins.Our results can provide a theoretical basis for controlling wheat allergenicity in food proces sing or producing hypoallergenic food.展开更多
The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the t...The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the thermal cycle in weld zone during double-sided asymmetrical T1G backing welding is investigated. The results show that the workpiece experiences double-peak thermal cycle in double-sided asymmetrical TIG backing welding. On the one hand, the fore arc has the pre- heating effect on the rear pass, and the pre-heating temperature depends on the distance between the double arcs, the heat input of fore arc, and the initial temperature of workpiece. On the other hand, the rear arc has the post-heating effect on the fore pass. The mutual effects of two heat sources decrease with the increase of arc distance.展开更多
A parameter perturbation for the unsteady-state heat-transfer characteristics of honeycomb regenerator is presented. It is limited to the cases where the storage matrix has a small wall thickness so that no temperatur...A parameter perturbation for the unsteady-state heat-transfer characteristics of honeycomb regenerator is presented. It is limited to the cases where the storage matrix has a small wall thickness so that no temperature variation in the matrix perpendicular to the flow direction is considered. Starting from a two-phase transient thermal model for the gas and storage matrix, an approximate solution for regenerator heat transfer process is derived using the multiple-scale method for the limiting case where the longitudinal heat conduction of solid matrix is far less than the convective heat transfer between the gas and the solid. The regenerator temperature profiles are expressed as Taylor series of the coefficient of solid heat conduction item in the model. The analytical validity is shown by comparing the perturbation solution with the experiment and the numerical solution. The results show that it is possible for the perturbation to improve the effectiveness and economics of thermal research on regenerators.展开更多
The serious environmental threat caused by petroleum-based plastics has spurred more researches in developing substitutes from renewable sources.Starch is desirable for fabricating bioplastic due to its abundance and ...The serious environmental threat caused by petroleum-based plastics has spurred more researches in developing substitutes from renewable sources.Starch is desirable for fabricating bioplastic due to its abundance and renewable nature.However,limitations such as brittleness,hydrophilicity,and thermal properties restrict its widespread application.To overcome these issues,covalent adaptable network was constructed to fabricate a fully bio-based starch plastic with multiple advantages via Schiff base reactions.This strategy endowed starch plastic with excellent thermal processability,as evidenced by a low glass transition temperature(T_(g)=20.15℃).Through introducing Priamine with long carbon chains,the starch plastic demonstrated superior flexibility(elongation at break=45.2%)and waterproof capability(water contact angle=109.2°).Besides,it possessed a good thermal stability and self-adaptability,as well as solvent resistance and chemical degradability.This work provides a promising method to fabricate fully bio-based plastics as alternative to petroleum-based plastics.展开更多
The VO2 thin film with high performance of metal-insulator transition （MIT） is prepared on R-sapphire substrate for the first time by magnetron sputtering with rapid thermal process （RTP）. The electrical character...The VO2 thin film with high performance of metal-insulator transition （MIT） is prepared on R-sapphire substrate for the first time by magnetron sputtering with rapid thermal process （RTP）. The electrical characteristic and THz transmittance of MIT in VO2 film are studied by four-point probe method and THz time domain spectrum （THz-TDS）. X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, atomic force microscopy （AFM）, and search engine marketing （SEM） are employed to analyze the crystalline structure, valence state, surface morphology of the film. Results indicate that the properties of VO2 film which is oxidized from the metal vanadium film in oxygen atmosphere are improved with a follow- up RTP modification in nitrogen atmosphere. The crystallization and components of VO2 film are improved and the film becomes compact and uniform. A better phase transition performance is shown that the resistance changes nearly 3 orders of magnitude with a 2-~C hysteresis width and the THz transmittances are reduced by 64% and 60% in thermal and optical excitation respectively.展开更多
There is an increasing attention on oxidative derivatives of triglycerides,a group of potential thermal processing induced food toxicants,which are formed during the thermal processing of food lipids.This review aims ...There is an increasing attention on oxidative derivatives of triglycerides,a group of potential thermal processing induced food toxicants,which are formed during the thermal processing of food lipids.This review aims to summarize current knowledge about their formation mechanisms,detection approaches,and toxicology impacts.Oxidative derivatives of triglycerides are generated through the oxidation,cyclization,polymerization,and hydrolysis of triglycerides under high-temperature and abundant oxygen.The analytical techniques,including GC,HPSEC,MS,^(1)H-NMR were discussed in analyzing these components.In addition,their toxic effects on human health,including effects on the liver,intestines,cardiovascular system,immune system,and metabolism were elucidated.Information in this review could be used to improve the understanding of oxidative derivatives of triglycerides and ultimately improve academic and industrial strategies for eliminating these compounds in thermal processing food systems.展开更多
There are lots of physical changes and chemical reactions in the processes of iron and steel making,these processes are quite complex in the aspect of heat transfer.The processes of iron and steel making can be approx...There are lots of physical changes and chemical reactions in the processes of iron and steel making,these processes are quite complex in the aspect of heat transfer.The processes of iron and steel making can be approximately divided into three kinds.The first kinds are the processes of fusion metallurgy which involve enormous chemical reactions,such as blast furnace,converter,electric furnace and coke oven.The second kinds are the processes of heating and cooling which are mainly the physical changes,such as walking-beam reheating furnace,annular heating furnace and car-type furnace.The third kinds are the processes of heat treatment which mainly adjust metallurgical structure of metal,such as roller hearth heat treatment furnace,strip continuous heat treatment vertical/horizontal furnace and HPH bell-type annealing furnace.Every process can only be finished in particular thermal equipment.And all the physical and chemical processes mentioned above must obey first principles of engineering thermodynamics,heat&mass transfer,hydromechanics,combustion,metallurgy physical chemistry etc,and which can be summarized as principle of heat transfer,mass transfer,momentum transfer and chemistry reaction.In this paper,based on first principle of heat and mass transfer in iron and steel making processes,a series of mathematical models of thermal equipments and processes are presented.Such as the model of hot-blast stoves,coke oven,CDQ-boiler system,sintering,reheating furnace,soaking furnace,annular heating furnace,roller hearth heat treatment furnace,strip continuous heat treatment vertical/horizontal furnace,HPH bell-type annealing furnace,control cooling of medium plate,burner,heat exchanger and regenerative burner etc.The on-line application of the model is based on experimental certification of the mathematical model.And finally the computer optimization system of metallurgical thermal process is obtained.展开更多
The relationship between the arrangement of tungsten-halogen lamps and the uniformity of irradiance received by the wafer is discussed, and a sort of axial-symmetrical lamps-array is designed to guarantee that the irr...The relationship between the arrangement of tungsten-halogen lamps and the uniformity of irradiance received by the wafer is discussed, and a sort of axial-symmetrical lamps-array is designed to guarantee that the irradiation on the edge is approximately the same as the one on the center of the wafer. The magnitude of temperature on the wafer vs. the power of tungsten-halogen lamps is calculated numerically.展开更多
In order to study the mechanism of vacuum fluxless soldering on the conditions of laser heating, the method of measuring temperature by the thermocouple is used to analyze the spreading and wetting process of both flu...In order to study the mechanism of vacuum fluxless soldering on the conditions of laser heating, the method of measuring temperature by the thermocouple is used to analyze the spreading and wetting process of both fluxless Sn-Pb solder in the vacuum surroundings and flux Sn-Pb solder on Cu pad. Solder spreading and wetting affected by the soldering thermal process is also discussed according to the thermodynamics principle. Results show that vacuum fluxless soldering demands higher temperature, and the fall of the solder surface tension is the important factor achieving fluxless laser soldering.展开更多
Chlorine(Cl) is extensively present in solid wastes, causing significant problems during the thermal conversion of waste to energy or fuels, by combustion, gasification or pyrolysis.This paper introduces the analytica...Chlorine(Cl) is extensively present in solid wastes, causing significant problems during the thermal conversion of waste to energy or fuels, by combustion, gasification or pyrolysis.This paper introduces the analytical methods for determining the Cl content in solid materials and presents the concentrations of Cl in various types of wastes, as reported in literature. Then, it provides a comprehensive analysis on the Cl emission behavior and Cl species formed during the thermal processing of the inorganic and organic Cl sources. The challenges resulted from the reactions between the formed Cl species and the ferrous metals, the heavy metals and the organic matters are summarized and discussed, e.g., high temperature corrosion, heavy metal evaporation and dioxin formation. The quality degradation of products(oil, char and syngas) by Cl is analyzed. Finally, the available controlling methods of Cl emission, including pre-treatment(water washing, sorting,microwave irradiation and stepwise pyrolysis) and in-furnace(absorbents, co-treatment and catalysts) methods are assessed.展开更多
In order to improve the process of co-reduction of oxide powder, a new mechano-thermal process was de-signed to produce high-dispersed W-Cu composite powder by high temperature oxidation, short time high-energymilling...In order to improve the process of co-reduction of oxide powder, a new mechano-thermal process was de-signed to produce high-dispersed W-Cu composite powder by high temperature oxidation, short time high-energymilling and reduction at lower temperature. The particle size, oxygen content and their sintering abilities of W-Cucomposite powder in different conditions were analyzed. The results show that after a quick milling of the oxidepowder for about 3-10 h, the reduction temperature of the W-Cu oxide powder can be lowered to about 650 ℃ from700-750 ℃ owning to the lowering of particle size of the oxide powder. The average particle size of W-Cu powder af-ter reduction at 650 ℃ is about 0.5 μm smaller than that reduced at 750 ℃. After sintering at 1 200 ℃ for 1 h inhydrogen atmosphere, the relative density and thermal conductivity of final products (W-20Cu) can attain 99.5%and 210 W @ m-1 @ K-1 respectively.展开更多
Kombucha is a fermented tea beverage that has gained popularity in recent years,often being associated with potential health benefits.However,its microbiological instability introduces challenges for its commercial pr...Kombucha is a fermented tea beverage that has gained popularity in recent years,often being associated with potential health benefits.However,its microbiological instability introduces challenges for its commercial production and distribution.This study evaluated the effectiveness of thermal treatments on microbiological inactivation,ethanol,organic acids,and antioxidant properties across four commercial products.Thermal treatments(75℃/12 min,70℃/10 min,63℃/10 min,61℃/2 min)effectively achieved microbiological inactivation and maintained product stability.Heat-treated products maintained ethanol and acetic acid levels throughout storage,whereas untreated samples showed progressive yeast proliferation and alcohol accumula-tion.Phenolic content and antioxidant capacity were preserved post-treatment,with no consistent decline.Multivariate analysis revealed that brand-specific formulations and storage duration caused compositional variations in untreated products.These findings highlight the relevance of appropriately designed thermal processing strategies in this particular category of commercial kombucha products and provide practical guid-ance for producers seeking to ensure microbiological safety and physicochemical stability during storage.展开更多
This original research integrated lipidomics and HS-SPME-GC-MS to unravel lipid-flavor interplay in channel catfish under steaming(ST)and roasting(RO)processing.1085 kinds of lipids were identified using lipidomics,an...This original research integrated lipidomics and HS-SPME-GC-MS to unravel lipid-flavor interplay in channel catfish under steaming(ST)and roasting(RO)processing.1085 kinds of lipids were identified using lipidomics,and phosphatidylcholine(PC)emerged as a critical flavor precursor,showing significant downregulation(Log2FC:-0.71 to-1.40)post-processing.Lipidomics revealed thermal-driven polarization,during which medium-chain fatty acids(C_(8)-C_(10))declined,while long-chain species(C_(16)-C_(22))increased.Correlation analysis highlighted PC’s strong association with aldehydes(hexanal,nonanal),confirmed by chemical simulations where PC(C18:2/C16:0)oxidation generated key flavor compounds like hexanal,octanal,acetone,which were highly consistent with key VOCs from authentic channel catfish flesh.Dual degradation pathways were identified:(1)glycerol backbone cleavage yielding acetone and(2)linoleic acid autoxidation via radical-mediatedβ-scission,producing hexanal and trans-2-heptenal.RO intensified aldehyde formation due to higher thermal stress.Notably,1-octen-3-ol was absent in PC oxidation products,suggesting alternative enzymatic or non-lipid pathways.This work established PC as a pivotal flavor precursor and mapped its oxidation routes,offering novel insights into lipid-driven flavor chemistry in thermally processed fishery foods.展开更多
Highland barley,which is a cereal grain rich inβ-glucan,is commonly subjected to various thermal processing methods prior to consumption.Although the influence ofβ-glucan on gut microbiota has attracted considerable...Highland barley,which is a cereal grain rich inβ-glucan,is commonly subjected to various thermal processing methods prior to consumption.Although the influence ofβ-glucan on gut microbiota has attracted considerable research interest,how thermal treatments affect its prebiotic function remains unclear.In this study,highland barley flour was processed using four thermal methods:steam heating,stir frying,film baking,and extrusion puffing,followed by the extraction of highland barleyβ-glucan(HBBG).Results revealed that extrusion-puffed HBBG exhibited the most pronounced prebiotic effects.It significantly increased the overall microbial abundance(p<0.05)and specifically enhanced the growth of several beneficial bacteria,establishing Lactobacillus as a characteristic genus.Furthermore,the extrusion puffing(EP)group showed the highest production of short-chain fatty acids(SCFAs),along with elevated abundances of pathways associated with carbohydrate and amino acid metabolism.Structurally,extrusion puffing resulted in moderate molecular weight,highβ-glycosidic bond retention,microporosity,high water-holding capacity,and low viscosity of HBBG,which collectively improving microbial accessibility.This study provides a theoretical foundation for optimizing thermal processing technologies of highland barleyβ-glucan and suggests that extrusion-puffed HBBG has potential as a novel prebiotic product.展开更多
基金National Natural Science Foundation of China(U2242203, 42305164, 42175105)Key Innovation Team of China Meteorological Administration (CMA2023ZD08)Science and Technology Research Project of Guangdong Meteorological Service (GRMC2023M31)。
文摘Precise high-temperature weather forecasts are essential, as heatwaves are increasing in frequency under the ongoing climate change. Land-surface schemes have been demonstrated to be crucial to numerical weather predictions.However, few studies have explored the impact of land surface schemes on short-range high-temperature weather forecasts via operational numerical weather prediction models. To evaluate the impact of the soil thermal process on high-temperature weather forecasts, we coupled the soil thermal process of the state-of-the-art Common Land Model(CoLM) with the South China operational numerical weather prediction model(CMA-TRAMS) and compared the coupled model with the original CMA-TRAMS, which incorporated the Simplified Model for land Surface(SMS). Contrast experiments based on two versions of CMA-TRAMS were conducted for the year 2022 when persistent extreme heatwaves were observed in Central-East China. The results are as follows:(1) Short-range high-temperature weather forecasts were sensitive to soil thermal process schemes. The original CMA-TRAMS clearly underestimated the summertime near-surface air temperature(T2m) over almost all areas of China, whereas the CoLM led to a reduction of the negative biases by approximately 0.5°C.(2) The more accurate initial soil temperatures and the deeper soil structure used in the CoLM test contributed to actual predictions of soil heat flux, soil temperature, and T2m. Nevertheless, the SMS test failed to capture upward heat transport from deeper to shallower soil layers at night due to the shallow soil structure and lower accuracy of the bottom and initial soil temperatures.(3) Higher soil temperatures resulted in increased near-surface moisture and cloud cover in the CoLM test, which led to the warmer soil and further mitigated the cold biases of T2m through reduced longwave and shortwave radiation losses at the land surface.
文摘The direct conversion of methane using a dielectric barrier discharge has been experimentally studied. Experiments with different values of flow rates and discharge voltages have been performed to investigate the effects on the conversion and reaction products both qualitatively and quantitatively. Experimental results indicate that the maximum conversion of methane has been 80% at an input flow rate of 5 ml/min and a discharge voltage of 4 kV. Experimental results also show that the optimum condition has occurred at a high discharge voltage and higher input flow rate. In terms of product distribution, a higher flow rate or shorter residence time can increase the selectivity for higher hydrocarbons. No hydrocarbon product was detected using the thermal method, except hydrogen and carbon. Increasing selectivity for ethane was found when Pt and Ru catalysts presented in the plasma reaction. Hydrogenation of acetylene in the catalyst surface could have been the reason for this phenomenon as the selectivity for acetylene in the products was decreasing.
基金the National Natural Science Foundation of China(52074114)the Hunan Provincial Innovation Foundation for Post graduate(CX20190314)。
文摘The precipitation evolutions of Mg-Al-Zn alloys play essential roles in their mechanical properties,corrosion performance,formability,plastic deformation mechanisms and texture development.In the present work,the precipitation evolutions of AZ80 magnesium alloy during both non-isothermal and isothermal processes were unraveled by utilizing in situ electrical resistivity monitoring,hardness testing,differential scanning calorimetry and microstructural characterization.The results showed that discontinuous precipitation(DP)and continuous precipitation(CP)occurred competitively during non-isothermal and isothermal processes.The precipitation of dominantβ-Mg17 Al12 phase during non-isothermal processes was highly dependent on the thermal history.During isothermal processes,the precipitation behavior of AZ80 magnesium alloy could be considered as the functions of holding temperature and time.At lower temperatures,massive DP and CP were gradually formed to equally strengthen the alloy.At higher temperatures,the Ostwald coarsening was characterized in the later stages and indicated to slightly soften the alloy.Isothermal time-temperature-precipitation curves and quantitative precipitate evolution were estimated to unravel precipitation characteristics and their strengthening functions.
基金financially supported by the 2018 annual three gorges follow-up research project of the three gorges office of the State Council (YYNY-2017-01)
文摘Qingke(highland hull-less barley)is a grain replete with substantial nutrients and bioactive ingredients.In this study,we evaluated the effects of boiling(BO),steaming(ST),microwave baking(MB),far-infrared baking(FB),steam explosion(SE),and deep frying(DF)on bioactive components,phenolic compounds,and antioxidant activities of Qingke compared with the effects of traditional roast(TR).Results showed that the soluble dietary fiber,beta-glucan and water-extractable pentosans of Qingke in dry heat processes of TR,SE,MB and FB had a higher content compared with other thermal methods and had a better antioxidant activity of hydroxyl radical scavenging and a better reduction capacity,while those in wet heat processes of BO and ST had a better antioxidant activity of ABTS radical scavenging and a better Fe^(2+) chelating ability.DF-and SE-Qingke had a higher content of tocopherol,phenolic,and flavonoid.Overall,6 free phenolic compounds and 12 bound phenolic compounds of Qingke were identified,and free phenolic compounds suffered more damage during thermal processing.Principal component analysis showed that SE had more advantages in retaining and improving the main biological active ingredients of Qingke,and it may be the best method for treating Qingke.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea,funded by the Ministry of Science,ICT,and Future Planning(NRF Award No.NRF-2019R1A2C2002024 and 2021R1A4A1031357)supported by the Basic Science Research Program through NRF funded by the Ministry of Education(NRF Award No.NRF2020R1A6A1A03043435)。
文摘Engineering point defects such as metal and oxygen vacancies play a crucial role in manipulating the electrical,optical,and catalytic properties of oxide semiconductors for solar water splitting.Herein,we synthesized nanoporous CuBi_(2)O_(4)(np-CBO)photocathodes and engineered their surface point defects via rapid thermal processing(RTP)in controlled atmospheres(O_(2),N_(2),and vacuum).We found that the O_(2)-RTP treatment of np-CBO increased the charge carrier density effectively without hampering the nanoporous morphology,which was attributed to the formation of copper vacancies(VCu).Further analyses revealed that the amounts of oxygen vacancies(Vo)and Cu^(1+)were reduced simultaneously,and the relative electrochemical active surface area increased after the O_(2)-RTP treatment.Notably,the point defects(VC_(u),Cu^(1+),and Vo)regulated np-CBO achieved a superb water-splitting photocurrent density of-1.81 m A cm^(-2) under simulated sunlight illumination,which is attributed to the enhanced charge transport and transfer properties resulting from the regulated surface point defects.Finally,the reversibility of the formation of the point defects was checked by sequential RTP treatments(O_(2)-N_(2)-O_(2)-N_(2)),demonstrating the strong dependence of photocurrent response on the RTP cycles.Conclusively,the surface point defect engineering via RTP treatment in a controlled atmosphere is a rapid and facile strategy to promote charge transport and transfer properties of photoelectrodes for efficient solar water-splitting.
基金supported by the National Natural Science Foundation of China(31872904)。
文摘Wheat allergy has become a serious health threat worldwide and its prevalence has increased alarmingly in the past few years.Factors such as food matrix and food processing may alter the structure of wheat proteins,and hence affect its allergenic properties.However,few reports have focused on the influence of Chinese traditional starter fermentation on wheat allergy.In this study,5 starters from different regions of China were used for fermentation,and protein characteristics were monitored by sodium dodecyl sulfate polyacrylamide gel electropheresis,and immunoreactivity analyzed by immunoassay with allergenic serum was obtained from New Zealand white rabbits.The allergenicity of steamed and baked matrices was also evaluated.The results showed that the allergenicity of wheat dough was basically increased at the beginning and then decreased during fermentation,but specific trends depend on different starters.With the progress of fermentation,especially as pH value decreased to 3.0-4.0,the allergenicity decreased significantly.Baking and steaming can reduce the allergenicity of wheat matrix,but fermentation is not a key factor affecting the allergenic activity of proteins.Our results can provide a theoretical basis for controlling wheat allergenicity in food proces sing or producing hypoallergenic food.
文摘The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the thermal cycle in weld zone during double-sided asymmetrical T1G backing welding is investigated. The results show that the workpiece experiences double-peak thermal cycle in double-sided asymmetrical TIG backing welding. On the one hand, the fore arc has the pre- heating effect on the rear pass, and the pre-heating temperature depends on the distance between the double arcs, the heat input of fore arc, and the initial temperature of workpiece. On the other hand, the rear arc has the post-heating effect on the fore pass. The mutual effects of two heat sources decrease with the increase of arc distance.
基金Item Sponsored by High Technology Research Development Program of China(2005AA001020,2001AA514013)
文摘A parameter perturbation for the unsteady-state heat-transfer characteristics of honeycomb regenerator is presented. It is limited to the cases where the storage matrix has a small wall thickness so that no temperature variation in the matrix perpendicular to the flow direction is considered. Starting from a two-phase transient thermal model for the gas and storage matrix, an approximate solution for regenerator heat transfer process is derived using the multiple-scale method for the limiting case where the longitudinal heat conduction of solid matrix is far less than the convective heat transfer between the gas and the solid. The regenerator temperature profiles are expressed as Taylor series of the coefficient of solid heat conduction item in the model. The analytical validity is shown by comparing the perturbation solution with the experiment and the numerical solution. The results show that it is possible for the perturbation to improve the effectiveness and economics of thermal research on regenerators.
基金supported by the National Natural Science Foundation of China(U23A6005 and 32171721)State Key Laboratory of Pulp and Paper Engineering(202305,2023ZD01,2023C02)+1 种基金Guangdong Province Basic and Application Basic Research Fund(2023B1515040013)the Fundamental Research Funds for the Central Universities(2023ZYGXZR045).
文摘The serious environmental threat caused by petroleum-based plastics has spurred more researches in developing substitutes from renewable sources.Starch is desirable for fabricating bioplastic due to its abundance and renewable nature.However,limitations such as brittleness,hydrophilicity,and thermal properties restrict its widespread application.To overcome these issues,covalent adaptable network was constructed to fabricate a fully bio-based starch plastic with multiple advantages via Schiff base reactions.This strategy endowed starch plastic with excellent thermal processability,as evidenced by a low glass transition temperature(T_(g)=20.15℃).Through introducing Priamine with long carbon chains,the starch plastic demonstrated superior flexibility(elongation at break=45.2%)and waterproof capability(water contact angle=109.2°).Besides,it possessed a good thermal stability and self-adaptability,as well as solvent resistance and chemical degradability.This work provides a promising method to fabricate fully bio-based plastics as alternative to petroleum-based plastics.
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.61101055)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20100032120029)
文摘The VO2 thin film with high performance of metal-insulator transition （MIT） is prepared on R-sapphire substrate for the first time by magnetron sputtering with rapid thermal process （RTP）. The electrical characteristic and THz transmittance of MIT in VO2 film are studied by four-point probe method and THz time domain spectrum （THz-TDS）. X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, atomic force microscopy （AFM）, and search engine marketing （SEM） are employed to analyze the crystalline structure, valence state, surface morphology of the film. Results indicate that the properties of VO2 film which is oxidized from the metal vanadium film in oxygen atmosphere are improved with a follow- up RTP modification in nitrogen atmosphere. The crystallization and components of VO2 film are improved and the film becomes compact and uniform. A better phase transition performance is shown that the resistance changes nearly 3 orders of magnitude with a 2-~C hysteresis width and the THz transmittances are reduced by 64% and 60% in thermal and optical excitation respectively.
基金funded by the National Natural Science Foundation of China (Grant No.32272426).
文摘There is an increasing attention on oxidative derivatives of triglycerides,a group of potential thermal processing induced food toxicants,which are formed during the thermal processing of food lipids.This review aims to summarize current knowledge about their formation mechanisms,detection approaches,and toxicology impacts.Oxidative derivatives of triglycerides are generated through the oxidation,cyclization,polymerization,and hydrolysis of triglycerides under high-temperature and abundant oxygen.The analytical techniques,including GC,HPSEC,MS,^(1)H-NMR were discussed in analyzing these components.In addition,their toxic effects on human health,including effects on the liver,intestines,cardiovascular system,immune system,and metabolism were elucidated.Information in this review could be used to improve the understanding of oxidative derivatives of triglycerides and ultimately improve academic and industrial strategies for eliminating these compounds in thermal processing food systems.
文摘There are lots of physical changes and chemical reactions in the processes of iron and steel making,these processes are quite complex in the aspect of heat transfer.The processes of iron and steel making can be approximately divided into three kinds.The first kinds are the processes of fusion metallurgy which involve enormous chemical reactions,such as blast furnace,converter,electric furnace and coke oven.The second kinds are the processes of heating and cooling which are mainly the physical changes,such as walking-beam reheating furnace,annular heating furnace and car-type furnace.The third kinds are the processes of heat treatment which mainly adjust metallurgical structure of metal,such as roller hearth heat treatment furnace,strip continuous heat treatment vertical/horizontal furnace and HPH bell-type annealing furnace.Every process can only be finished in particular thermal equipment.And all the physical and chemical processes mentioned above must obey first principles of engineering thermodynamics,heat&mass transfer,hydromechanics,combustion,metallurgy physical chemistry etc,and which can be summarized as principle of heat transfer,mass transfer,momentum transfer and chemistry reaction.In this paper,based on first principle of heat and mass transfer in iron and steel making processes,a series of mathematical models of thermal equipments and processes are presented.Such as the model of hot-blast stoves,coke oven,CDQ-boiler system,sintering,reheating furnace,soaking furnace,annular heating furnace,roller hearth heat treatment furnace,strip continuous heat treatment vertical/horizontal furnace,HPH bell-type annealing furnace,control cooling of medium plate,burner,heat exchanger and regenerative burner etc.The on-line application of the model is based on experimental certification of the mathematical model.And finally the computer optimization system of metallurgical thermal process is obtained.
基金Foundationfor Key Youth Teachers from Hunan Province(521105237) Natural Science Foundation of HunanUniversity(521101805)
文摘The relationship between the arrangement of tungsten-halogen lamps and the uniformity of irradiance received by the wafer is discussed, and a sort of axial-symmetrical lamps-array is designed to guarantee that the irradiation on the edge is approximately the same as the one on the center of the wafer. The magnitude of temperature on the wafer vs. the power of tungsten-halogen lamps is calculated numerically.
基金This project is supported by National Natural Science Foundation of China !(59671063)
文摘In order to study the mechanism of vacuum fluxless soldering on the conditions of laser heating, the method of measuring temperature by the thermocouple is used to analyze the spreading and wetting process of both fluxless Sn-Pb solder in the vacuum surroundings and flux Sn-Pb solder on Cu pad. Solder spreading and wetting affected by the soldering thermal process is also discussed according to the thermodynamics principle. Results show that vacuum fluxless soldering demands higher temperature, and the fall of the solder surface tension is the important factor achieving fluxless laser soldering.
基金supported by the National Natural Science Foundation of China (Nos. 51621005, 51676170)the Key Project for Strategic International Collaboration on Science and Technology Innovation of the National Key R&D Program of China (No. 2016YFE0202000)+1 种基金 the Fundamental Research Funds for the Central Universities (No. 2017FZA4013)the Academic Raising Star Training Program for PhD Student of Zhejiang University
文摘Chlorine(Cl) is extensively present in solid wastes, causing significant problems during the thermal conversion of waste to energy or fuels, by combustion, gasification or pyrolysis.This paper introduces the analytical methods for determining the Cl content in solid materials and presents the concentrations of Cl in various types of wastes, as reported in literature. Then, it provides a comprehensive analysis on the Cl emission behavior and Cl species formed during the thermal processing of the inorganic and organic Cl sources. The challenges resulted from the reactions between the formed Cl species and the ferrous metals, the heavy metals and the organic matters are summarized and discussed, e.g., high temperature corrosion, heavy metal evaporation and dioxin formation. The quality degradation of products(oil, char and syngas) by Cl is analyzed. Finally, the available controlling methods of Cl emission, including pre-treatment(water washing, sorting,microwave irradiation and stepwise pyrolysis) and in-furnace(absorbents, co-treatment and catalysts) methods are assessed.
基金Project （50405026） supported by the National Natural Science Foundation of China Project（20051022） supported by the Department of Science and Technology of Shanxi Province, China
基金Project (59871064) supported by the National Nature Science Foundation of China
文摘In order to improve the process of co-reduction of oxide powder, a new mechano-thermal process was de-signed to produce high-dispersed W-Cu composite powder by high temperature oxidation, short time high-energymilling and reduction at lower temperature. The particle size, oxygen content and their sintering abilities of W-Cucomposite powder in different conditions were analyzed. The results show that after a quick milling of the oxidepowder for about 3-10 h, the reduction temperature of the W-Cu oxide powder can be lowered to about 650 ℃ from700-750 ℃ owning to the lowering of particle size of the oxide powder. The average particle size of W-Cu powder af-ter reduction at 650 ℃ is about 0.5 μm smaller than that reduced at 750 ℃. After sintering at 1 200 ℃ for 1 h inhydrogen atmosphere, the relative density and thermal conductivity of final products (W-20Cu) can attain 99.5%and 210 W @ m-1 @ K-1 respectively.
文摘Kombucha is a fermented tea beverage that has gained popularity in recent years,often being associated with potential health benefits.However,its microbiological instability introduces challenges for its commercial production and distribution.This study evaluated the effectiveness of thermal treatments on microbiological inactivation,ethanol,organic acids,and antioxidant properties across four commercial products.Thermal treatments(75℃/12 min,70℃/10 min,63℃/10 min,61℃/2 min)effectively achieved microbiological inactivation and maintained product stability.Heat-treated products maintained ethanol and acetic acid levels throughout storage,whereas untreated samples showed progressive yeast proliferation and alcohol accumula-tion.Phenolic content and antioxidant capacity were preserved post-treatment,with no consistent decline.Multivariate analysis revealed that brand-specific formulations and storage duration caused compositional variations in untreated products.These findings highlight the relevance of appropriately designed thermal processing strategies in this particular category of commercial kombucha products and provide practical guid-ance for producers seeking to ensure microbiological safety and physicochemical stability during storage.
基金funded by Jiangsu Agricultural Industry Technology System(JATS[2023]464)Mount Taishan Industrial Leading Talents(Blue Project)China Agriculture Research System(CARS-45-28).
文摘This original research integrated lipidomics and HS-SPME-GC-MS to unravel lipid-flavor interplay in channel catfish under steaming(ST)and roasting(RO)processing.1085 kinds of lipids were identified using lipidomics,and phosphatidylcholine(PC)emerged as a critical flavor precursor,showing significant downregulation(Log2FC:-0.71 to-1.40)post-processing.Lipidomics revealed thermal-driven polarization,during which medium-chain fatty acids(C_(8)-C_(10))declined,while long-chain species(C_(16)-C_(22))increased.Correlation analysis highlighted PC’s strong association with aldehydes(hexanal,nonanal),confirmed by chemical simulations where PC(C18:2/C16:0)oxidation generated key flavor compounds like hexanal,octanal,acetone,which were highly consistent with key VOCs from authentic channel catfish flesh.Dual degradation pathways were identified:(1)glycerol backbone cleavage yielding acetone and(2)linoleic acid autoxidation via radical-mediatedβ-scission,producing hexanal and trans-2-heptenal.RO intensified aldehyde formation due to higher thermal stress.Notably,1-octen-3-ol was absent in PC oxidation products,suggesting alternative enzymatic or non-lipid pathways.This work established PC as a pivotal flavor precursor and mapped its oxidation routes,offering novel insights into lipid-driven flavor chemistry in thermally processed fishery foods.
基金supported by the National Key Research and Development Program of China(2021YFD2100200/2021YFD2100201)the Opening Project of Key Laboratory of Coarse Cereal Processing of Ministry of Agriculture and Rural Affairs,and Sichuan Engineering and Technology Research Center of Coarse Cereal Industralization,Chengdu University(No.2023CC005).
文摘Highland barley,which is a cereal grain rich inβ-glucan,is commonly subjected to various thermal processing methods prior to consumption.Although the influence ofβ-glucan on gut microbiota has attracted considerable research interest,how thermal treatments affect its prebiotic function remains unclear.In this study,highland barley flour was processed using four thermal methods:steam heating,stir frying,film baking,and extrusion puffing,followed by the extraction of highland barleyβ-glucan(HBBG).Results revealed that extrusion-puffed HBBG exhibited the most pronounced prebiotic effects.It significantly increased the overall microbial abundance(p<0.05)and specifically enhanced the growth of several beneficial bacteria,establishing Lactobacillus as a characteristic genus.Furthermore,the extrusion puffing(EP)group showed the highest production of short-chain fatty acids(SCFAs),along with elevated abundances of pathways associated with carbohydrate and amino acid metabolism.Structurally,extrusion puffing resulted in moderate molecular weight,highβ-glycosidic bond retention,microporosity,high water-holding capacity,and low viscosity of HBBG,which collectively improving microbial accessibility.This study provides a theoretical foundation for optimizing thermal processing technologies of highland barleyβ-glucan and suggests that extrusion-puffed HBBG has potential as a novel prebiotic product.
