Gel-state polybenzimidazole proton exchange membranes with flexible alkyl sulfonic acid side chains for a wider operating temperature range(25–240 ℃)

High-temperature proton exchange membrane fuel cells(HT-PEMFC) possess distinct technical advantages of high output power, simplified water/heat management, increased tolerance to fuel impurities and diverse fuel sources, within the temperature range of 120–200 ℃. However, for practical automobile applications, it was crucial to broaden their low-temperature operating window and enable cold start-up capability. Herein, gel-state phosphoric acid(PA) doped sulfonated polybenzimidazole(PBI) proton exchange membranes(PEMs) were designed and synthesized via PPA sol-gel process and in-situ sultone ring-opening reactions with various proton transport pathways based on absorbed PA, flexible alkyl chain connected sulfonic acid groups and imidazole sites. The effects of flexible alkyl sulfonic acid side chain length and content on PA doping level, proton conductivity, and membrane stability under different temperature and relative humidity(RH) were thoroughly investigated. The prepared gel-state membranes contained a self-assembled lamellar and porous structure that facilitated the absorption of a large amount of PA with rapid proton transporting mechanisms. At room temperature, the optimized membrane exhibited a proton conductivity of 0.069 S cm^(-1), which was further increased to 0.162 and 0.358 S cm^(-1)at 80 and 200 ℃, respectively, without additional humidification. The most significant contribution of this work was demonstrating the feasibility of gel-state sulfonated PBI membranes in expanding HT-PEMFC application opportunities over a wider operating range of 25 to 240 ℃.

Moderately concentrated electrolyte enabling high-performance lithium metal batteries with a wide working temperature range

The electrolyte integrated with lithium metal anodes is subjected to the issues of interfacial compatibility and stability,which strongly influence the performances of high-energy lithium metal batteries.Here,we report a new electrolyte recipe viz.a moderately concentrated electrolyte comprising of 2.4 M lithium bis(fluorosulfonyl)imide(LiFSI)in a cosolvent mixture of fluorinated ethylene carbonate(FEC)and dimethyl carbonate(DMC)with relatively high ion conductivity.Owing to the preferential decomposition of LiFSI and FEC,an inorganic-rich interphase with abundant Li_(2)O and LiF nanocrystals is formed on lithium metal with improved robustness and ion transfer kinetics,enabling lithium plating/stripping with an extremely low overpotential of~8 mV and the average CE of 97%.When tested in Li||LiFePO_(4) cell,this electrolyte provides long-term cycling with a capacity retention of 98.3%after 1000 cycles at 1 C and an excellent rate performance of 20 C,as well as an areal capacity of 1.35 mA h cm^(-2)at the cathode areal loading of 9 mg cm^(-2).Moreover,the Li||LiFePO_(4) cell exhibits excellent wide-temperature performances(-40~60℃),including long-term cycling stability over 2600 cycles without visible capacity fading at 0℃,as well as extremely high average CEs of 99.6%and 99.8% over 400 cycles under-20℃ and 45℃.

A phenomenological model for plastic flow behavior of rotating band material with a large temperature range

The plastic flow behavior of the rotating band material is investigated in this paper. The rotating band material is processed from H96 brass alloy, which is hardened to a much higher yield strength compared to the annealed one. The dynamically uniaxial compression behavior of the material is tested using the split Hopkinson pressure bar(SHPB) with temperature and strain rate ranging from 297 to 1073 K and500 to 3000 s^(-1), respectively, and a phenomenological plastic flow stress model is developed to describe the mechanical behavior of the material. The material is found to present noticeable temperature sensitivity and weak strain-rate sensitivity. The construction of the plastic flow stress model has two steps. Firstly, three univariate stress functions, taking plastic strain, plastic strain rate and temperature as independent variable, respectively, are proposed by fixing the other two variables. Then, as the three univariate functions describe the special cases of flow stress behavior under various conditions, the principle of stress compatibility is adopted to obtain the complete flow stress function. The numerical results show that the proposed plastic flow stress model is more suitable for the rotating band material than the existing well-known models.

Progress in Electrolyte Engineering of Aqueous Batteries in a Wide Temperature Range

Aqueous rechargeable batteries are safe and environmentally friendly and can be made at a low cost;as such,they are attracting attention in the field of energy storage.However,the temperature sensitivity of aqueous batteries hinders their practical application.The solvent water freezes at low temperatures,and there is a reduction in ionic conductivity,whereas it evaporates rapidly at high temperatures,which causes increased side reactions.This review discusses recent progress in improving the performance of aqueous batteries,mainly with respect to electrolyte engineering and the associated strategies employed to achieve such improvements over a wide temperature domain.The review focuses on fi ve electrolyte engineer-ing(aqueous high-concentration electrolytes,organic electrolytes,quasi-solid/solid electrolytes,hybrid electrolytes,and eutectic electrolytes)and investigates the mechanisms involved in reducing the solidifi cation point and boiling point of the electrolyte and enhancing the extreme-temperature electrochemical performance.Finally,the prospect of further improving the wide temperature range performance of aqueous rechargeable batteries is presented.

Effect of cold stratification on the temperature range for germination of Pinus koraiensis

Germination at low spring temperatures may offer a competitive advantage for the growth and survival of plant species inhabiting temperate forest ecosystems.Pinus koraiensis is a dominant species in temperate forests of northeastern China.Its seeds exhibit primary morphophysiological dormancy following dispersal in autumn,limiting natural or artificial regeneration:direct seeding and planting seedlings in spring.The aim of this study was to determine the optimum cold stratification temperature that induces germination to increase towards lower temperatures.Seeds from two populations(Changbaishan and Liangshui)were cold stratified at 0,5 and 10℃.Germination to incubation temperatures(10/5,20/10,25/15 and 30/20℃;14/10 h day/night)were determined after 2 and 4 weeks,and 5.5 and6.5 months of cold stratification.After 5.5 months,approximately 68-91%of seeds from both populations germinated at incubation temperatures of 25/15℃and 30/20℃,regardless of cold stratification temperatures.When the cold stratification temperature was reduced to 0℃and the period increased to 6.5 months,germination at 10/5℃significantly improved,reaching 37%and 64%for the Changbaishan and Liangshui populations,respectively.After 6.5 months of cold stratification,there was a significant linear regression between cold stratification temperatures and germination at10/5℃.The range in temperatures allowing for germination gradually expanded to include lower temperatures with decreasing cold stratification temperatures from 10 to 5℃and further to 0℃.

Association Between Diurnal Temperature Range and Respiratory Tract Infections

Objective This study aimed to assess the association between emergency-room visits for respiratory tract infection （RTI） with diurnal temperature range （DTR）, a weather parameter closely associated with urbanization and global climate change. Methods We conducted a semiparametric time-series analysis to estimate the percentage increase in emergency-room visits for RTI associated with changes in DTR after adjustment for daily weather conditions （temperature and relative humidity） and outdoor air pollution. Results DTR was significantly associated with daily emergency-room visits for RTI. An increase of 1 ~C in the current-day （LO） and in the 2-day moving average （L01） DTR corresponded to a 0.94% [95% confidence interval （CI）, 0.34%-1.55%] and 2.08% （95% CI, 1.24%-2.93%） increase in emergency-room visits for RTI, respectively. Conclusion DTR was associated with increased risk of RTI. More studies are needed to understand the impact of DTR on respiratory health.

On the Contrasting Decadal Changes of Diurnal Surface Temperature Range between the Tibetan Plateau and Southeastern China during the 1980s–2000s

The diurnal surface temperature range （DTR） has become significantly smaller over the Tibetan Plateau （TP） but larger in southeastern China, despite the daily mean surface temperature having increased steadily in both areas during recent decades. Based on ERA-Interim reanalysis data covering 1979-2012, this study shows that the weakened DTR over TP is caused by stronger warming of daily minimum surface temperature （Tmin） and a weak cooling of the daily maximum surface temper- ature （Tmax）; meanwhile, the enhanced DTR over southeastern China is mainly associated with a relatively stronger/weaker warming of Tmax/Tmin. A further quantitative analysis of DTR changes through a process-based decomposition method-- the Coupled Surface-Atmosphere Climate Feedback Response Analysis Method （CFRAM）--indicates that changes in radia- tive processes are mainly responsible for the decreased DTR over the TR In particular, the increased low-level cloud cover tends to induce the radiative cooling/warming during daytime/nighttime, and the increased water vapor helps to decrease the DTR through the stronger radiative wanning during nighttime than daytime. Contributions from the changes in all radiative processes （over -2℃） are compensated for by those from the stronger decreased surface sensible heat flux during daytime than during nighttime （approximately 2.5℃）, but are co-contributed by the changes in atmospheric dynamics （approximately -0.4℃） and the stronger increased latent heat flux during daytime （approximately -0.8℃）. In contrast, the increased DTR over southeastern China is mainly contributed by the changes in cloud, water vapor and atmospheric dynamics. The changes in surface heat fluxes have resulted in a decrease in DTR over southeastern China.

Quantifying the response of surface urban heat island to urbanization using the annual temperature cycle model

Urban heat island(UHI),driving by urbanization,plays an important role in urban sustainability under climate change.However,the quantification of UHI’s response to urbanization is still challenging due to the lack of robust and continuous temperature and urbanization datasets and reliable quantification methods.This study proposed a framework to quantify the response of surface UHI(SUHI)to urban expansion using the annual temperate cycle model.We built a continuous annual SUHI series at the buffer level from 2003 to 2018 in the Jing-Jin-Ji region of China using MODIS land surface temperature and imperviousness derived from Landsat.We then investigated the spatiotemporal dynamic of SUHI under urban expansion and examined the underlying mechanism.Spatially,the largest SUHI interannual variations occurred in suburban areas compared to the urban center and rural areas.Temporally,the increase in SUHI under urban expansion was more significant in daytime compare to nighttime.We found that the seasonal variation of SUHI was largely affected by the seasonal variations of vegetation in rural areas and the interannual variation was mainly attributed to urban expansion in urban areas.Additionally,urban greening led to the decrease in summer daytime SHUI in central urban areas.These findings deepen the understanding of the long-term spatiotemporal dynamic of UHI and the quantitative relationship between UHI and urban expansion,providing a scientific basis for prediction and mitigation of UHI.

Elevational patterns of temperature and humidity in the middle Tianshan Mountain area in Central Asia

The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and diurnal variations in the elevational gradients of air temperature and humidity on the southern and northern slopes in the middle Tianshan Mountain Range using data collected throughout the year via HOBO data loggers. The measurements were conducted at 12 different elevations from 1548 to 3277 m from September 2004 to August 2005. The results showed that the annual mean air temperature decreased along the elevational gradients with temperature lapse rates of(0.71±0.20)°C/100 m and(0.59±0.05)°C/100 m on the northern and southern slopes, respectively. The annual mean absolute humidity significantly decreased with increasing elevation on the northern slope but showed no significant trend on the southern slope. The annual mean relative humidity did not show a significant trend on the northern slope but increased with increasing elevation on the southern slope. The mean air temperature lapse rate exhibited significant seasonal variation, which is steeper insummer and shallower in winter, and this value varied between 0.37°C/100 m and 0.75°C/100 m on the southern slope and between 0.30°C/100 m and 1.02°C/100 m on the northern slope. The mean absolute and relative humidity also exhibited significant seasonal variations on both slopes, with the maximum occurring in summer and the minimum occurring in winter or spring. The monthly diurnal range of air temperature on both slopes was higher in spring than in winter. The annual range of air temperature on the southern slope was higher than that on the northern slope. Our results suggest that significant spatiotemporal variations in humidity and temperature lapse rate are useful when analyzing the relationships between species range sizes and climate in mountain areas.

Diurnal Temperature Range and Daily Emergency Room Admissions among the Elderly in Beijing,China

In recent years, more attentions have been paid to the association between climate change and human health. Increasing and more variable global surface temperature is one of the key climatic change factors which have been consistently reported about the effect on human health. So far, more researches have revealed that temperature lead not only to direct deaths and illnesses but also to aggravation of cardiovascular and respiratory diseases. Typically, the relationship between temperature and mortality or morbidity is V-, U-, or J- shaped, with optimum temperature corresponding to the lowest point in the temperature mortality curve.

Characteristic Analysis of Diurnal Temperature Range in Guigang

[ Objective] The aim was to analyze diurnal temperature range in Guigang from 1960 to 2009. [Method] Based on the conventional me- teorological data （mean daily temperature, mean maximum temperature, and mean minimum temperature） of Guigang region during 1960 -2009, the Diurnal Temperature Range （DTR） and the DTR trend were studied. [ Result] The annual minimum temperatures and the annual maximum temperature were significantly increasing. The maximum temperature rose less than minimum temperature and spatial changes of daily temperature narrowed gradually from the Tropic of Cancer to the two sides. The extreme diurnal temperature decreased mostly in stations far away from the Tropic of Cancer and the significance was strong. The extreme diurnal temperature decreased little in stations close to the Tropic of Cancer. Influ- ences of different factors on daily difference varied. DTR positively correlated with sunshine duration, and negatively related to total cloudiness, rel- ative humidity and precipitation. DTR had insignificant relation with average wind speed. [ Conclusion] The study provided basis for the understand- ing of climate changes in Guigang.

Diurnal Temperature Range as a Novel Risk Factor for Sudden Infant Death

Objective To assess the relationship between diurnal temperature range （DTR） and sudden infant death （SID） between 2001 and 2004 in Shanghai,China.Methods We conducted a time‐stratified case‐crossover analysis to estimate the percent increase of SID associated with changes in DTR after adjustment for daily weather conditions （temperature and relative humidity） and outdoor air pollution.Results DTR was significantly associated with daily SID.An increase of 1 °C in the current‐day （L0） and in the 2‐day moving average （L01） DTR corresponds to a 1.56% （95% CI：0.97%,2.15%） and a 1.89% （95% CI：1.17%,2.60%） increase in SID,respectively.Conclusion An increased DTR was associated with an increased risk of SID in Shanghai.More studies are needed to understand the effect of DTR on infant deaths.

A Calorimetric Study Assisted with First Principle Calculations of Specific Heat for Si-Ge Alloys within a Broad Temperature Range

Calorimetric measurements are performed to determine the specific heat of Si-xat.% Ge(where x = 0, 10, 30,50, 70, 90 and 100) alloys within a broad temperature range from 123 to 823 K. The measured specific heat increases dramatically at low temperatures, and the composition dependence of specific heat is evaluated from the experimental results. Meanwhile, the specific heat at constant volume, the thermal expansion, and the bulk modulus of Si and Ge are investigated by the first principle calculations combined with the quasiharmonic approximation. The negative thermal expansion is observed for both Si and Ge. Furthermore, the isobaric specific heat of Si and Ge is calculated correspondingly from OK to their melting points, which is verified by the measured results and accounts for the temperature dependence in a still boarder range.

Relation between martensitic transformation temperature range and lattice distortion ratio of NiMnGaCoCu Heusler alloys

In order to study the relation between martensitic transformation temperature range AT （where AT is the difference between martensitic transformation start and finish temperature） and lattice distortion ratio （c/a） of martensitic transforma~ tion, a series of Ni46Mnz8_xGa22Co4Cux （x = 2-5） Heusler alloys is prepared by arc melting method. The vibration sample magnetometer （VSM） experiment results show that AT increases when x 〉 4 and decreases when x 〈 4 with x increasing, and the minimal AT （about 1 K） is found at x = 4. Ambient X-ray diffraction （XRD） results show that AT is proportional to c/a for non-modulated Ni46Mn28_xGa22Co4Cux （x = 2-5） martensites. The relation between AT and c/a is in agreement with the analysis result obtained from crystal lattice mismatch model. About 1000-ppm strain is found for the sample at x = 4 when heating temperature increases from 323 K to 324 K. These properties, which allow a modulation of AT and temperature-induced strain during martensitic transformation, suggest Ni46Mn24Ga22Co4Cu4 can be a promising actuator and sensor.

Average Annual Temperature Changes in the Holocene in China

Abstract: In 1876 Blytt proposed a post-glacial climatic classification, maintaining that the then temperature fluctuated 1–2°C higher or lower than that today. Lamb (1969) held that in Europe “the axis of the subtropical high pressure belt was generally displaced north by about 10° latitudes” during the Hypsithermal and that the temperature was three to six times higher than that in the postglacial period.

Observed and Future Changes in the Temperature of the State of Jalisco, México Using Climdex and PRECIS

In the present study we analyzed the average and extreme temperatures observed and simulated by regional models in the State of Jalisco, Mexico. Data of daily mean, minimum and maximum temperatures of 208 stations distributed all over the State during the period 1971-2000 have been used to study the observed changes in the values of average and extreme temperatures. In addition, an assessment of future scenarios for the average and extreme temperatures associated with the increase in the concentration of greenhouse gases (GHG) was performed using simulations of a PRECIS (Providing Regional Climate for Impact Studies) regional climate modeling to create the climate for present (1971-2000), and future projections for the years 2020, 2050 and 2080. Observational analysis of the 208 stations suggests warming through increased intensity and frequency of hot events, with a decrease in the frequency of cold events. More than 35% to 76% of the stations have a tendency to a decrease in the number of cold events and 39% to 64% of the stations show a growing trend in the hot events. The percentage of stations showing warming through the indices of intensity of the highest maximums, lowest minimum temperatures is 37% to 70% and 30% to 65% of the stations, respectively. Observational analysis for the State of Jalisco as a whole also shows similar results. Anomalies in the average and extreme temperatures per month during the data period show an increase (decrease) in the frequency of hot (cold) events for every month. In general, PRECIS simulations under both scenarios A1B and A2 indicate an increase in warm events and decrease of cold extreme events towards the end of the 21st century. Both show similar patterns, but the scenario A2 shows slightly lower magnitudes of projected changes. Temperatures are likely to increase all year, but it is expected that changes in summer will be more prominent.

Analysis on Change Characteristics of Diurnal Temperature Range in Benxi County from 1958 to 2010

Based on annual mean maximum and minimum temperatures,diurnal temperature range,precipitation,sunshine,total cloud cover and water barometric pressure data in Benxi County from 1958 to 2010,using statistical analysis,the results show that the annual and seasonal diurnal temperature ranges present significant decreasing tendencies,and the reducing tendency is the most remarkable in winter. Autumn reducing tendency is stronger than that in spring,and it is the weakest in summer. Annual and seasonal average temperatures,average maximum and minimum temperatures all present the remarkable rising trends. Rising trend of the minimum temperature is more significant than that of the maximum temperature. The monthly mean diurnal temperature range also presents reducing tendency,and the most reducing scope appear in January and February. Annual and season diurnal temperature range changes are related to sunshine,mean minimum temperature,mean maximum temperature,precipitation,total cloud cover and water barometric pressure,but various essential factors are different in each season. Annual mean temperature,annual mean minimum temperature,annual mean maximum temperature and annual diurnal temperature range all have sudden changes,but the age is inconsistent.

Wide temperature range,air stable,transparent,and self-powered photodetectors enabled by a hybrid film of graphene and singlewalled carbon nanotubes

Transparent photovoltaic devices(TPVDs)have attracted increasing attention in emerging electronic devices.As the application scenarios extend,there raise higher requirements regarding the stability and operating temperature range of TPVDs.In this work,a unique preparation strategy is proposed for air stable TPVD with a wide operating temperature range,i.e.,a nanoscale architecture termed as H-TPVD is constructed that integrates a free-standing and highly transparent conductive hybrid film of graphene and single-walled carbon nanotubes(G-SWNT TCF for short)with a metal oxide NiO/TiO_(2)heterojunction.The preparation approach is suitable for scaling up.Thanks to the excellent transparent conductivity of the freestanding G-SWNT hybrid film and the ultrathin NiO/TiO_(2)heterojunction(100 nm),H-TPVD selectively absorbs the ultraviolet(UV)band of sunlight and has a transparency of up to 71%in the visible light.The integrated nanoscale architecture manifests the significant holecollecting capability of the G-SWNT hybrid film and the efficient carrier generation and separation within the ultrathin NiO/TiO_(2)heterojunction,resulting in excellent performance of the H-TPVD with a specific detectivity of 2.7×1010 Jones.Especially,the freestanding G-SWNT TCF is a super stable and non-porous two-dimensional film that can insulate gas molecules,thereby protecting the surface properties of NiO/TiO_(2)heterojunctions and enhancing the stability of H-TPVD.Having subjected to 20,000 cycles and storage in air for three months,the performance parameters such as photo-response signal,output power,and specific detectivity show no noticeable degradation.In particular,the as-fabricated self-powered H-TPVD can operate over a wide temperature range from^(−1)80 to 300°C,and can carry out solar-blind UV optical communication in this range.In addition,the 4×4 array H-TPVD demonstrates clear optical imaging.These results make it possible for H-TPVD to expand its potential application scenarios.

Trend in pan evaporation and its attribution over the past 50 years in China

Trends in pan evaporation are widely relevant to the hydrological community as indicators of hydrological and climate change. Pan evaporation has been decreasing in the past few decades over many large areas with differing climates globally. This study analyzes pan evaporation data from 671 stations in China over the past 50 years in order to reveal the trends of it and the corresponding trend attribution. Mann-Kendall test shows a significant declining trend in pan evaporation for most stations, with an average decrease of 17.2 mm/10a in China as a whole, the rate of decline was the steepest in the humid region （29.7 mm/10a）, and was 17.6 mm/10a and 5.5 mm/10a in the semi-humid/semi-arid region and arid region, respectively. Complete correlation coefficients of pan evaporation with 7 climate factors were computed, and decreases in diurnal temperature range （DTR）, SD （sunshine duration） and wind speed were found to be the main attributing factors in the pan evaporation declines. Decrease in DTR and SD may relate to the increase of clouds and aerosol as well as the other pollutants, and decrease in wind speed to weakening of the Asian winter and summer monsoons under global climate warming.

Electrostatic Interaction Tailored Anion-Rich Solvation Sheath Stabilizing High-Voltage Lithium Metal Batteries

Through tailoring interfacial chemistry,electrolyte engineering is a facile yet effective strategy for highperformance lithium(Li)metal batteries,where the solvation structure is critical for interfacial chemistry.Herein,the effect of electrostatic interaction on regulating an anion-rich solvation is firstly proposed.The moderate electrostatic interaction between anion and solvent promotes anion to enter the solvation sheath,inducing stable solid electrolyte interphase with fast Li+transport kinetics on the anode.This asdesigned electrolyte exhibits excellent compatibility with Li metal anode(a Li deposition/stripping Coulombic efficiency of 99.3%)and high-voltage LiCoO_(2) cathode.Consequently,the 50μm-thin Li||high-loading LiCoO_(2) cells achieve significantly improved cycling performance under stringent conditions of high voltage over 4.5 V,lean electrolyte,and wide temperature range(-20 to 60℃).This work inspires a groundbreaking strategy to manipulate the solvation structure through regulating the interactions of solvent and anion for highperformance Li metal batteries.