Effect of increasing rainfall on the thermal–moisture dynamics of permafrost active layer in the central Qinghai–Tibet Plateau

In the past several decades,the trend of rainfall have been significantly increasing in the Qinghai–Tibet Plateau,which inevitably leads to a change in the surface energy balance processes and thermal-moisture status of the permafrost active layers.However,the influence of mechanisms and associated effects of increasing rainfall on active layers are still poorly understood.Therefore,in this study,a validated coupled numerical water–vapor–heat model was applied for simulating the surface energy components,liquid and vapor water migration,and energy transfer within the permafrost active layer under the action of increasing rainfallin the case of an especially wet year.The obtained results demonstrate that the surface heat flux decreaseswith the increase in rainfall,and the dominant form of energy exchange between the ground and atmospherebecomes the latent heatflux,which is beneficial for the preservation of permafrost.The increasing rainfall will also cause the migration of liquid and vapor water,and the migration of liquid will be more significant.The liquid and vapor water migrationcaused by the increasing rainfallis also accompanied by energy transfer.With the increase in rainfall,the decrease in total soil heat flux directly leads to a cooling effect on the soil,and then the upper limit of the frozen soil rises,which alleviates the degradation of permafrost.These results provide further insights into engineering structures,regional ecological climate change,hydrology,and environmental issues in permafrost regions.

Thermal and Moisture Comfort Properties of Down Jacket Fabrics

In order to study the thermal and moisture comfort properties of down jacket fabrics,20 popular down jacket fabrics were selected from the market.The basic specifications of the samples were tested,and thermal and moisture performance tests were conducted.The obtained thermal and moisture indicators were analyzed,and then combined with the subjective evaluation results to obtain the regression equation for the evaluation of the comprehensive thermal and moisture comfort of down jacket fabrics.The air permeability,the thermal resistance,the warm and cold feeling and the moisture permeability were tested,and the results were divided into 5 levels.The results showed that the consistency of the air permeability and the moisture permeability of down jacket fabrics studied was better,and the thermal insulation of the down jacket fabrics with coating was better.The thickness of the down jacket fabrics had an effect on the warm and cold feeling of instant contact,and the consistency of subjective and objective warm and cold feeling was better.The obtained comprehensive evaluation equation of the thermal and moisture comfort has certain guiding significance for the thermal and moisture comfort of down jacket fabrics.

Investigating spatial and temporal variations of soil moisture content in an arid mining area using an improved thermal inertia model

Mining operations can usually lead to environmental deteriorations. Underground mining activities could cause an extensive decrease in groundwater level and thus a dramatic variation in soil moisture content（SMC）. In this study, the spatial and temporal variations of SMC from 2001 to 2015 at two spatial scales（i.e., the Shendong coal mining area and the Daliuta Coal Mine） were analyzed using an improved thermal inertia model with a long-term series of Landsat TM/OLI（TM=Thematic Mapper and OLI=Operational Land Imager） data. Our results show that at large spatial scale（the Shendong coal mining area）, underground mining activities had insignificant negative impacts on SMC and that at small spatial scale（the Daliuta Coal Mine）, underground mining activities had significant negative impacts on SMC. Trend analysis of SMC demonstrated that areas with decreasing trend of SMC were mainly distributed in the mined area, indicating that underground mining is a primary cause for the drying trend in the mining region in this arid environment.

Experimental and theoretical study on thermal and moisture characteristics of new-type bamboo structure wall

Thermal and moisture characteristics of the bamboo structure wall were tested in natural climate and three representative variation processes of heat and moisture： heating from solar radiation in summer at normal temperature and humidity, heating from solar radiation in summer at normal temperature and high humidity after rain, humidifying from brash in summer at high temperature and normal humidity. The results show that, in summer, the largest temperature difference between external and internal surface of the 28 mm-thick bamboo plywood wall is 11.73℃ （at 15：40） and the largest strain difference is 136 μm/m （at 18：50）, both in ambient and indoor conditioned environment. In heating process, lengthways of the wall surface are in contracting strain while transverse ways are in expanding strain at initial stage and in contracting strain during later period. When the high temperature wall is humidified by rain, the surface temperature drops, moisture content increases and the expanding strain is presented on the surface during the whole process. Temperature and moisture content are two important factors which affect thermal and moisture stress （TMS） of the bamboo structure wall. The TMS is not only related to temperature and moisture content, but also greatly affected by temperature gradient, moisture content gradient and rates of changing.

A Darcy-Law Based Model for Heat and Moisture Transfer in a Hill Cave

A hill can be regarded as an environmental carrier of heat.Water,rocks and the internal moisture naturally pre-sent in such environment constitute a natural heat accumulator.In the present study,the heat and moisture trans-fer characteristics in a representative hill cave have been simulated via a method relying on the Darcy’s law.The simulations have been conducted for both steady and unsteady conditions to discern the influence of permeability and geometric parameters on the thermal and moisture transfer processes.The reliability of the simulation has been verified through comparison of the numerical results with the annual observation data.As revealed by the numericalfindings,the internal temperature of the hill accumulator is proportional to the permeability,outside surface temperature,overground height,underground constant temperature layer depth,and underground tem-perature of the hill,and it is inversely proportional to the horizontal size of the hill.Moreover,in the considered case,the order of magnitude of the permeability of the hill is contained in the range 10-15–10-13,and displays a certain sensitivity to the rainwater seepage.

Multifunctional dual-anion compensation of amphoteric glycine hydrochloride enabled highly stable perovskite solar cells with prolonged carrier lifetime

Throughout years,the two-step spin-coating process is the most common method to prepare organic lead halide perovskite materials.However,the short reaction time of dropping the solution at the second step means that PbI2 cannot be completely transformed into perovskite phase.To solve this problem,we report the introduction of glycine hydrochloride(GlyHCl)into the second step of the two-step spin-coating process to prepare a FA_(0.9)MA_(0.1)PbI_(3-x)%-GlyHCl perovskite material(namely FAMA-x%-GlyHCl,where FA=formamidinium,MA=methylammonium,and x%stands for the molar ratio of GlyHCl added in FA iodide/MA iodide(FAI/MAI)precursor solution).The Cl−ion in GlyHCl assists the formation ofα-phase perovskite,and the-COO−group coordinates with Pb2+cation in a bridging way,making up for the anion vacancy in perovskite lattice and resulting in high absorption intensity.The perovskite solar cells(PSCs)based on FAMA-9%-GlyHCl achieve a long carrier lifetime(527.0 ns),a photoelectric conversion efficiency(PCE)of 19.40%and good thermal stability,maintaining 85.8%of the initial PCE after being continuously heated at 60℃for 500 h.This study helps to solve the problem of incomplete reaction in the two-step spin-coating process and puts forward a new solution for preparing high coverage perovskite films with large grain size.

Superabsorbent Fibers for Comfortable Disposable Medical Protective Clothing

Disposable medical protective clothing for 2019-nCoV mainly consists of stacked layers with nanopore films,polymer coated nonwoven fabrics and melt-blown nonwoven fabrics against anti-microbial and anti-liquid penetration.However,such structures lack moisture permeability and breathability leading to an uncomfortable,stuffy wearing experience.Here,we propose a novel medical protective clothing material with a superabsorbent layer to enhance moisture absorption.Poly(acrylic acid-co-acrylamide)/polyvinyl alcohol superabsorbent fibers(PAAAM/PVA fibers)were prepared via wet spinning.And the superabsorbent composite layer was stacked from PAAAM/PVA fibers,bamboo pulp fibers(BPF)and ethylene-propyl-ene side by side fibers(ESF).The novel disposable medical protective composite fabric was obtained through gluing the superabsorbent layer to the inner surface of strong antistatic polypropylene nonwoven fabric.The resultant composite fabric possesses excellent absorption and retention capacity for sweat,up to 12.3 g/g and 63.8%,and a maximum hygroscopic rate of 1.04 g/h,higher than that of the conventional material(only 0.53 g/h).The moisture permeability of the novel material reached 12,638.5 g/(m^(2) d),which was 307.6%of the conventional material.The novel material can effectively reduce the humidity inside the protective clothing and significantly improve the comfort of medical staff.