Thermal runaway(TR)is considered a significant safety hazard for lithium batteries,and thermal protection materials are crucial in mitigating this risk.However,current thermal protection materials generally suffer fro...Thermal runaway(TR)is considered a significant safety hazard for lithium batteries,and thermal protection materials are crucial in mitigating this risk.However,current thermal protection materials generally suffer from poor mechanical properties,flammability,leakage,and rigid crystallization,and they struggle to continuously block excess heat transfer and propagation once thermal saturation occurs.This study proposes a novel type of thermal protection material:an aerogel coupled composite phase change material(CPCM).The composite material consists of gelatin/sodium alginate(Ge/SA)composite biomass aerogel as an insulating component and a thermally induced flexible CPCM made from thermoplastic polyester elastomer as a heat-absorbing component.Inspired by power bank,we coupled the aerogel with CPCM through the binder,so that CPCM can continue to‘charge and store energy’for the aerogel,effectively absorbing heat,delaying the heat saturation phenomenon,and maximizing the duration of thermal insulation.The results demonstrate that the Ge/SA aerogel exhibits excellent thermal insulation(with a temperature difference of approximately 120℃ across a 1 cm thickness)and flame retardancy(achieving a V-0 flame retardant rating).The CPCM exhibits high heat storage density(811.9 J g^(−1)),good thermally induced flexibility(bendable above 40℃),and thermal stability.Furthermore,the Ge/SA-CPCM coupled composite material shows even more outstanding thermal insulation performance,with the top surface temperature remaining at 89℃ after 100 min of exposure to a high temperature of 230℃.This study provides a new direction for the development of TR protection materials for lithium batteries.展开更多
Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging becaus...Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.展开更多
Exploiting advanced nanocomposites isochronally integrating outstanding thermal conductivity(TC)and electromagnetic interference shielding effectiveness(EMI SE)can boost the cutting-edge application of phase change ma...Exploiting advanced nanocomposites isochronally integrating outstanding thermal conductivity(TC)and electromagnetic interference shielding effectiveness(EMI SE)can boost the cutting-edge application of phase change materials.Here,we report a tiramisu-like composite(GMP),where the typical“crust-and-cheese”hierarchical structure is replicated by an innovative two-step bidirectional freezing assembly(BFA)and compressive densification.Hierarchical-aligned graphene array(G-GA)with ultralow thermal resistance is fabricated through 1st BFA and graphitization.During the 2nd BFA,the MXene-CNF crosslinking network with hydrogen-bond actions is used for encapsulating polyethylene glycol(PEG)onto the microlayers of the G-GA skeleton.Remarkably,the microlaminated GMP4 achieves a recorded TC of 34.05 W m^(-1) K^(-1),unprecedented EMI SE of 87.4 dB,and preferable enthalpy density of 179.4 J cm^(-3),along with leakage-free function,and eminent thermal durability.Furthermore,the GMP-loaded equipment is demonstrated for efficient microelectronics cooling and sustainable solar energy utilization.This work opens new avenues for multiscale designing multifunctional macro-composites,broadening the application prospects in advanced electronics and solar energy utilization systems.展开更多
The mass loss rate of CaF2-CaO-Al2O3-SiO2-MgO slag system originated from ANF-6 was studied with CaF2, CaO, Al2O3, SiO2 or MgO content as variables. The method of quadratic regression orthogonal design was used for th...The mass loss rate of CaF2-CaO-Al2O3-SiO2-MgO slag system originated from ANF-6 was studied with CaF2, CaO, Al2O3, SiO2 or MgO content as variables. The method of quadratic regression orthogonal design was used for the design and analysis of the experiment. The experimental results indicated that mass loss rate of slag can be increased by 6% with CaF2 changing from 50%to 65%. Mass loss increases with SiO2 , Al2O3 and MgO adding and decreases with CaO content increasing. Because of the reaction between oxide and fluoride in the slag pool, apparent mass loss of CaF2-Al2O3 CaO-SiO2 MgO slag system appears at melting point. This will cause obvious composition change of electroslag. In addition, the segregation occurs in the slag skin forming process. This is another reason causing the composition change of electroslag.展开更多
Ru O2·n H2O film was deposited on tantalum foils by electrodeposition and heat treatment using Ru Cl3·3H2O as precursor.Surface morphology, composition change and cyclic voltammetry from precursor to amorpho...Ru O2·n H2O film was deposited on tantalum foils by electrodeposition and heat treatment using Ru Cl3·3H2O as precursor.Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·n H2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2h, RuO2·n H2O electrode surface gains mass of2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly20% with voltage scan rate increasing from 5 to 250 m V/s.展开更多
The concentration of elements in molten metal of AZ31 magnesium alloy after long pulsed Nd：YAG laser processing was quantitatively analyzed by using calibration-free laser-induced breakdown spectroscopy （CF-LIBS）. ...The concentration of elements in molten metal of AZ31 magnesium alloy after long pulsed Nd：YAG laser processing was quantitatively analyzed by using calibration-free laser-induced breakdown spectroscopy （CF-LIBS）. The composition change in AZ31 magnesium alloy under different laser pulse width was also investigated. The experimental results showed that CF-LIBS can obtain satisfactory quantitative or semi-quantitative results for matrix or major elements, while only qualitative analysis was possible for minor or trace elements. Moreover, it is found that the chemical composition of molten metal will change after laser processing. The concentration of magnesium in molten metal is lower than that present in the base metal. The Mg loss increases with an increase of pulse width in the laser processing. This result shows that the selective vaporization of different elements is affected by the pulse width during laser processing.展开更多
The severe dependence of traditional phase change materials(PCMs)on the temperature-response and lattice deficiencies in versatility cannot satisfy demand for using such materials in complex application scenarios.Here...The severe dependence of traditional phase change materials(PCMs)on the temperature-response and lattice deficiencies in versatility cannot satisfy demand for using such materials in complex application scenarios.Here,we introduced metal ions to induce the self-assembly of MXene nanosheets and achieve their ordered arrangement by combining suction filtration and rapid freezing.Subsequently,a series of MXene/K^(+)/paraffin wax(PW)phase change composites(PCCs)were obtained via vacuum impregnation in molten PW.The prepared MXene-based PCCs showed versatile applications from macroscale technologies,successfully transforming solar,electric,and magnetic energy into thermal energy stored as latent heat in the PCCs.Moreover,due to the absence of binder in the MXene-based aerogel,MK3@PW exhibits a prime solar-thermal conversion efficiency(98.4%).Notably,MK3@PW can further convert the collected heat energy into electric energy through thermoelectric equipment and realize favorable solar-thermal-electric conversion(producing 206 mV of voltage with light radiation intensity of 200 mw cm^(−2)).An excellent Joule heat performance(reaching 105℃with an input voltage of 2.5 V)and responsive magnetic-thermal conversion behavior(a charging time of 11.8 s can achieve a thermal insulation effect of 285 s)for contactless thermotherapy were also demonstrated by the MK3@PW.Specifically,as a result of the ordered arrangement of MXene nanosheet self-assembly induced by potassium ions,MK3@PW PCC exhibits a higher electromagnetic shielding efficiency value(57.7 dB)than pure MXene aerogel/PW PCC(29.8 dB)with the same MXene mass.This work presents an opportunity for the multi-scene response and practical application of PCMs that satisfy demand of next-generation multifunctional PCCs.展开更多
Atractylodis Rhizoma,a traditional Chinese medicine with an extensive history of treating gastrointestinal disorders and other diseases,undergoes various processing methods in China to enhance its therapeutic efficacy...Atractylodis Rhizoma,a traditional Chinese medicine with an extensive history of treating gastrointestinal disorders and other diseases,undergoes various processing methods in China to enhance its therapeutic efficacy for specific conditions.However,a comprehensive report detailing the changes in chemical composition and pharmacological effects due to these processing methods is currently lacking.This article provides a systematic review of the commonly employed processing techniques for Atractylodis Rhizoma,including raw Atractylodis Rhizoma(SCZ),bran-fried Atractylodis Rhizoma(FCZ),deep-fried Atractylodis Rhizoma(JCZ),and rice water-processed Atractylodis Rhizoma(MCZ).It examines the alterations in chemical constituents and pharmacological activities resulting from these processes and elucidates the mechanisms of action of the primary components in the various processed forms of Atractylodis Rhizoma in the treatment of gastrointestinal diseases.展开更多
Graphene-based phase change composites hold significant potential for solar energy utilization,but their poor thermal conductivity hinders their practical applications.In this work,an air-dried graphene skele-ton(AGS)...Graphene-based phase change composites hold significant potential for solar energy utilization,but their poor thermal conductivity hinders their practical applications.In this work,an air-dried graphene skele-ton(AGS)with excellent thermal conductivity enhancement efficiency was constructed by the ice tem-plating method and syneresis,and the air-dried graphene phase change composite(AGP)was subse-quently obtained through vacuum-impregnating n-Docosane(C22)into AGS.The syneresis effectively re-duced the phonon scattering between graphene sheets within AGS and increased the density of AGS to 0.1701 g/cm3.Therefore,with a graphene skeleton loading of 23.82 wt.%,AGP exhibited excellent thermal conductivity of 9.867 W/(m K),outstanding electrical conductivity of 68.08 S/cm,and remarkable shape stability.Additionally,AGP demonstrated a melting enthalpy of 188.5 J/g and an outstanding solar-thermal conversion efficiency of 93.98%,showing enormous potential for the utilization of solar energy.展开更多
Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device...Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device level,which results in a gap to real applications.Here,we propose a controllable thermal rectification design towards building applications through the direct adhesion of composite thermal rectification material(TRM)based on PCM and reduced graphene oxide(rGO)aerogel to ordinary concrete walls(CWs).The design is evaluated in detail by combining experiments and finite element analysis.It is found that,TRM can regulate the temperature difference on both sides of the TRM/CWs system by thermal rectification.The difference in two directions reaches to 13.8 K at the heat flow of 80 W/m^(2).In addition,the larger the change of thermal conductivity before and after phase change of TRM is,the more effective it is for regulating temperature difference in two directions.The stated technology has a wide range of applications for the thermal energy control in buildings with specific temperature requirements.展开更多
Phase change materials(PCMs)are widely considered as promising energy storage materials for solar/electro-thermal energy storage.Nevertheless,the inherent low thermal/electrical conductivities of most PCMs limit their...Phase change materials(PCMs)are widely considered as promising energy storage materials for solar/electro-thermal energy storage.Nevertheless,the inherent low thermal/electrical conductivities of most PCMs limit their energy conversion efficiencies,hindering their practical applications.Herein,we fabricate a highly thermally/electrically conductive solid-solid phase change composite(PCC)enabled by forming aligned graphite networks through pressing the mixture of the trimethylolethane and porous expanded graphite(EG).Experiments indicate that both the thermal and electrical conductivities of the PCC increase with increasing mass proportion of the EG because the aligned graphite networks establish highly conductive pathways.Meanwhile,the PCC4 sample with the EG proportion of 20wt%can achieve a high thermal conductivity of 12.82±0.38W·m^(-1)·K^(-1)and a high electrical conductivity of 4.11±0.02S·cm^(-1)in the lengthwise direction.Furthermore,a solar-thermal energy storage device incorporating the PCC4,a solar selective absorber,and a highly transparent glass is developed,which reaches a high solar-thermal efficiency of 77.30±2.71%under 3.0 suns.Moreover,the PCC4 can also reach a high electro-thermal efficiency of 91.62±3.52%at a low voltage of 3.6V,demonstrating its superior electro-thermal storage performance.Finally,stability experiments indicate that PCCs exhibit stabilized performance in prolonged TES operations.Overall,this work offers highly conductive and cost-effective PCCs,which are suitable for large-scale and efficient solar/electro-thermal energy storage.展开更多
The theory of“Salt-processing enhancing drug into kidney meridian”was firstly put forward by Chen Jiamu,a medical doctor of Xin’an,in“Enlightening Primer of Materia Medica”.This theory integrates the theory of th...The theory of“Salt-processing enhancing drug into kidney meridian”was firstly put forward by Chen Jiamu,a medical doctor of Xin’an,in“Enlightening Primer of Materia Medica”.This theory integrates the theory of the five elements of Chinese medicine that the five flavors enter into the five viscera,and forms the theory of the role of the auxiliary materials of Chinese medicine concoctions.This theory is an important guiding significance for the clinical use of raw and cooked Chinese medicine tablets.At present,there are more studies on the theory of“Salt-processing enhancing drug into kidney meridian”in the literature,mainly focusing on the chemical composition,efficacy changes and the concoction mechanism of salt products of traditional Chinese medicines before and after salt preparation.There are relatively few review papers on the theory of“Salt-processing enhancing drug into kidney meridian”from the perspectives of auxiliary salt and attribution of meridians.In this paper,through reviewing relevant ancient books and literature,and on the basis of the previous review articles,this paper centers on the auxiliary salt,and conducts in-depth excavation and elaboration in terms of its sources,types,and the historical evolution of the salt production method.From the perspective of categorization,focusing on the core theory of“Kidney stores essence,governing reproduction,bone and generating marrow,water and brain”,we summarize the changes in efficacy before and after the salt preparation of kidney tonic traditional Chinese medicines,the changes in external and internal constituents as well as the scientific connotation of the concocting mechanism behind the effect-constituent changes.The scientific connotation of the concoction theory of“Salt-processing enhancing drug into kidney meridian”was initially elucidated,providing a new reference model for the study of the theory of Chinese medicine concoction attribution.展开更多
A new potassium nitrate （KNO3）]diatomite shape-stabilized composite phase change material （SS- CPCM） was prepared by the mixing and sintering method. KNO3 served as the phase change material （PCM） for thermal en...A new potassium nitrate （KNO3）]diatomite shape-stabilized composite phase change material （SS- CPCM） was prepared by the mixing and sintering method. KNO3 served as the phase change material （PCM） for thermal energy storage, while diatomite acted as the carrier matrix to provide the structural strength and prevent the leakage of PCM. It was found that KNO3 could be retained 65 wt% into pores and on surfaces of diatomite without the leakage of melted KNO3 from the SS-CPCM. The calculated filling rate of molten KNO3 that could enter into the disc-like shape pore of diatomite verified the scanning elec- tronic microscopy images of SS-CPCM. X-ray diffraction and Fourier transform infrared spectroscopy results showed that no reaction occurred between KNO3 and diatomite, performing good compatibility. Accord- ing to the differential scanning calorimetry results, after 50 thermal cycles, the phase change temperatures for melting and freezing of SS-CPCM with 65 wt% KNO3 were changed from 330.23 ℃ and 332.90 ℃ to 330.11 ℃ and 332.84 ℃ and corresponding latent heats varied from 60.52 J/g and 47.30 J/g to 54.64 J/g and 41.25 J/g, respectively. The KNO3/diatomite SS-CPCM may be considered as a potential storage media in solar power plants for thermal energy storage.展开更多
Electronic devices generate heat during operation and require efficient thermal management to extend the lifetime and prevent performance degradation.Featured by its exceptional thermal conductivity,graphene is an ide...Electronic devices generate heat during operation and require efficient thermal management to extend the lifetime and prevent performance degradation.Featured by its exceptional thermal conductivity,graphene is an ideal functional filler for fabricating thermally conductive polymer composites to provide efficient thermal management.Extensive studies have been focusing on constructing graphene networks in polymer composites to achieve high thermal conductivities.Compared with conventional composite fabrications by directly mixing graphene with polymers,preconstruction of three-dimensional graphene networks followed by backfilling polymers represents a promising way to produce composites with higher performances,enabling high manufacturing flexibility and controllability.In this review,we first summarize the factors that affect thermal conductivity of graphene composites and strategies for fabricating highly thermally conductive graphene/polymer composites.Subsequently,we give the reasoning behind using preconstructed three-dimensional graphene networks for fabricating thermally conductive polymer composites and highlight their potential applications.Finally,our insight into the existing bottlenecks and opportunities is provided for developing preconstructed porous architectures of graphene and their thermally conductive composites.展开更多
The development of functional composites with excellent thermal management capabilities and electro-magnetic interference(EMI)shielding has become extremely urgent for keeping up with the continuous improvement of the...The development of functional composites with excellent thermal management capabilities and electro-magnetic interference(EMI)shielding has become extremely urgent for keeping up with the continuous improvement of the operating speed and efficiency for electronic equipment.In this study,the biolog-ical wood-derived porous carbon(WPC)was determined as the supporting material to encapsulating polyethylene glycol(PEG),and a series of WPC/PEG/Fe_(3)O_(4) phase change composites(PCCs)with excel-lent shape stability,EMI shielding and thermal management capabilities were prepared via a simple vac-uum impregnation method.The Fe_(3)O_(4) magnetic particles modified PCCs have greatly improved the EMI shielding effectiveness(SE).The EMI SE of WP-4(7.5 wt.% Fe_(3)O_(4) in PEG)can be up to 55.08 dB between 8.2−12.4 GHz,however,the WP-0 without Fe_(3)O_(4) addition is only 40.08 dB.Meanwhile,the absorption ratio of electromagnetic waves(EMW)has also increased from 75.02%(WP-0)to 85.56%(WP-4),which effectively prevents secondary pollution.In addition,after wrapping a thin layer of polydimethylsiloxane resin(PDMS),the obtained WP-4 can maintain a high heat storage capacity(109.52 J/g)and good wa-ter stability.In short,the prepared WPC/PEG/Fe_(3)O_(4) PCCs have great potential application value in the thermal management and electromagnetic shielding requirements for electronic devices.展开更多
Phase change materials(PCMs)can store large amounts of energy in latent heat and release it during phase changes,which could be used to improve the freeze-thaw performance of soil.The composite phase change material w...Phase change materials(PCMs)can store large amounts of energy in latent heat and release it during phase changes,which could be used to improve the freeze-thaw performance of soil.The composite phase change material was prepared with paraffin as the PCM and 8%Class C fly ash(CFA)as the supporting material.Laboratory tests were conducted to reveal the influence of phase change paraffin composite Class C fly ash(CFA-PCM)on the thermal properties,volume changes and mechanical properties of expansive soil.The results show that PCM failed to establish a good improvement effect due to leakage.CFA can effectively adsorb phase change materials,and the two have good compatibility.CFA-PCM reduces the volume change and strength attenuation of the soil,and 8 wt.%PCM is the optimal content.CFA-PCM turns the phase change latent heat down of the soil and improves its thermal stability.CFA-PCM makes the impact small of freeze-thaw on soil pore structure damage and improves soil volume change and mechanical properties on a macroscopic scale.In addition,CFA-8 wt.%PCM treated expansive soil has apparent advantages in resisting repeated freeze-thaw cycles,providing a reference for actual engineering design.展开更多
Oleylamine （G18） and octanol （G8） were grafted onto the surfaces of the multi-walled carbon nanotubes （CNTs）. The grafted CNTs were dispersed into palmitic acid （PA） and paraffin wax （PW） to prepare phase ch...Oleylamine （G18） and octanol （G8） were grafted onto the surfaces of the multi-walled carbon nanotubes （CNTs）. The grafted CNTs were dispersed into palmitic acid （PA） and paraffin wax （PW） to prepare phase change composites. The heat storage/retrieval experiments showed that the composites kept stable after repeating melting and solidification for 80 times. The structure of the G18-CNT/PA and G8-CNT/PA was homogenous compared with the pristine CNT （P-CNT）/PA. The latent heat capacity （Ls） of solid liquid phase change of G18-CNT/PW was higher than that of PW while those of the G8-CNTI/PW and P-CNT/PW were lower than that of PW. Compared with PA, all PA based composites with both P-CNTs and grafted CNTs decreased Ls evidently. The Ls values of GI8-CNT composites in both matrices were higher than that of the counterparts of G8-CNT. The thermal conductivities of all the PA based composites in the study were higher than that of PA, as well as those of all the PW based composites. However, the thermal conductivities of the GI8-CNT composites in both matrixes were lower than those of the G8-CNT composites in both matrixes at all measured temperatures.展开更多
Introduction:Communities change over time due to disturbances,variations in climate,and species invasions.Biological soil crust communities are important because they contribute to erosion control and nutrient cycling...Introduction:Communities change over time due to disturbances,variations in climate,and species invasions.Biological soil crust communities are important because they contribute to erosion control and nutrient cycling.Crust types may respond differently to changes in environmental conditions:single-celled organisms and bryophytes quickly recover after a disturbance,while lichens are slow growing and dominate favorable sites.Community change in crusts has seldom been assessed using repeated measures.For this study,we hypothesized that changes in crust composition were related to disturbance,topographic position,and invasive vegetation.Methods:We monitored permanent plots in the Columbia Basin in 1999 and 2010 and compared changes in crust composition,cover,richness,and turnover with predictor variables of herbivore exclosure,elevation,heat load index,time since fire,presence of an invasive grass,and change in cover of the invasive grass.Results:Bryophytes were cosmopolitan with high cover.Dominant lichens did not change dramatically.Indicator taxa differed by monitoring year.Bryophyte and total crust cover declined,and there was lower turnover outside of herbivore exclosures.Lichen cover did not change significantly.Plots that burned recently had high turnover.Increase in taxon richness was correlated with presence of an invasive grass in 1999.Change in cover of the invasive grass was positively related to proportional loss and negatively related to gain.Conclusions:Composition and turnover metrics differed significantly over 11 years,though cover was more stable between years.This study can be a baseline for assessing change in crust composition due to anthropogenic influences.展开更多
Lignin is a polymer of phenylpropanoid compounds formed through a complex biosynthesis route, represented by a metabolic grid for which most of the genes involved have been sequenced in several plants, mainly in the m...Lignin is a polymer of phenylpropanoid compounds formed through a complex biosynthesis route, represented by a metabolic grid for which most of the genes involved have been sequenced in several plants, mainly in the model-plants Arabidopsis thaliana and Populus. Plants are exposed to different stresses, which may change lignin content and composition. In many cases, particularly for plant-microbe interactions, this has been suggested as defence responses of plants to the stress. Thus, understanding how a stressor modulates expression of the genes related with lignin biosynthesis may allow us to develop study-models to increase our knowledge on the metabolic control of lignin deposition in the cell wall. This review focuses on recent literature reporting on the main types of abiotic and biotic stresses that alter the biosynthesis of lignin in plants.展开更多
We studied forest vegetation at Lata-Tolma- Phagti, a protected area and part of Nanda Devi Biosphere Reserve in the western Himalaya. We analyzed community composition, population structure, regeneration patterns, an...We studied forest vegetation at Lata-Tolma- Phagti, a protected area and part of Nanda Devi Biosphere Reserve in the western Himalaya. We analyzed community composition, population structure, regeneration patterns, and projected development of future compositional patterns. We sampled ten 10 x 10 m quadrat for tree species in each of 30 forest stands. We sampled shrubs in ten 5 x 5 m quadrat, and herbs in twenty 1 x 1 m quadrat within each forest stand. We recorded 248 plant species from 8 forest communities. Broadly the demographic profiles at study sites exhibited progressive structures suggesting long term persistence of the communities/species. Density--diameter distribution revealed greater proportions of seedlings and a significant decline （P 〈 0.05） in the proportion of trees in older age/size classes. Of the 23 recorded tree species, 13.0 % showed good, 52.2 % fair, 26.1% poor and 8.7 % no regeneration. Differences in regeneration by species are indicative of future foreststructure and dynamics. Assessment of changes in structure of forest types provides baseline data for development of priorities for conservation of other representative land- scapes in the reserve as well as in the Himalaya.展开更多
基金supported by the National Key Research and Development Program of China(2022YFB3806501)the National Natural Science Foundation of China(22178050,22108026)+3 种基金the Young Elite Scientists Sponsorship Program by CAST(2021QNRC001)the Natural Science Foundation of Liaoning Province(2022-BS-091)the Dalian Science and Technology Innovation Fund Young Tech Star(2022RQ008)the Fundamental Research Funds for the Central Universities(DUT22LAB610).
文摘Thermal runaway(TR)is considered a significant safety hazard for lithium batteries,and thermal protection materials are crucial in mitigating this risk.However,current thermal protection materials generally suffer from poor mechanical properties,flammability,leakage,and rigid crystallization,and they struggle to continuously block excess heat transfer and propagation once thermal saturation occurs.This study proposes a novel type of thermal protection material:an aerogel coupled composite phase change material(CPCM).The composite material consists of gelatin/sodium alginate(Ge/SA)composite biomass aerogel as an insulating component and a thermally induced flexible CPCM made from thermoplastic polyester elastomer as a heat-absorbing component.Inspired by power bank,we coupled the aerogel with CPCM through the binder,so that CPCM can continue to‘charge and store energy’for the aerogel,effectively absorbing heat,delaying the heat saturation phenomenon,and maximizing the duration of thermal insulation.The results demonstrate that the Ge/SA aerogel exhibits excellent thermal insulation(with a temperature difference of approximately 120℃ across a 1 cm thickness)and flame retardancy(achieving a V-0 flame retardant rating).The CPCM exhibits high heat storage density(811.9 J g^(−1)),good thermally induced flexibility(bendable above 40℃),and thermal stability.Furthermore,the Ge/SA-CPCM coupled composite material shows even more outstanding thermal insulation performance,with the top surface temperature remaining at 89℃ after 100 min of exposure to a high temperature of 230℃.This study provides a new direction for the development of TR protection materials for lithium batteries.
基金financially supported by the China Postdoctoral Science Foundation(No.2024M751205)。
文摘Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.
基金support from the National Natural Science Foundation of China(No.21878218)the Tianjin Research Innovation Project for Postgraduate Students(No.2023KJ262)+2 种基金the State Grid Corporation of China’s Research Program(No.5419-202019385A)the Fundamental Research Funds for the Central Universities(No.92320006)the Tianjin Key Science and Technology Program(No.18ZXSZSF00030)。
文摘Exploiting advanced nanocomposites isochronally integrating outstanding thermal conductivity(TC)and electromagnetic interference shielding effectiveness(EMI SE)can boost the cutting-edge application of phase change materials.Here,we report a tiramisu-like composite(GMP),where the typical“crust-and-cheese”hierarchical structure is replicated by an innovative two-step bidirectional freezing assembly(BFA)and compressive densification.Hierarchical-aligned graphene array(G-GA)with ultralow thermal resistance is fabricated through 1st BFA and graphitization.During the 2nd BFA,the MXene-CNF crosslinking network with hydrogen-bond actions is used for encapsulating polyethylene glycol(PEG)onto the microlayers of the G-GA skeleton.Remarkably,the microlaminated GMP4 achieves a recorded TC of 34.05 W m^(-1) K^(-1),unprecedented EMI SE of 87.4 dB,and preferable enthalpy density of 179.4 J cm^(-3),along with leakage-free function,and eminent thermal durability.Furthermore,the GMP-loaded equipment is demonstrated for efficient microelectronics cooling and sustainable solar energy utilization.This work opens new avenues for multiscale designing multifunctional macro-composites,broadening the application prospects in advanced electronics and solar energy utilization systems.
基金Item Sponsored by National Natural Science Foundation of China(50644040)
文摘The mass loss rate of CaF2-CaO-Al2O3-SiO2-MgO slag system originated from ANF-6 was studied with CaF2, CaO, Al2O3, SiO2 or MgO content as variables. The method of quadratic regression orthogonal design was used for the design and analysis of the experiment. The experimental results indicated that mass loss rate of slag can be increased by 6% with CaF2 changing from 50%to 65%. Mass loss increases with SiO2 , Al2O3 and MgO adding and decreases with CaO content increasing. Because of the reaction between oxide and fluoride in the slag pool, apparent mass loss of CaF2-Al2O3 CaO-SiO2 MgO slag system appears at melting point. This will cause obvious composition change of electroslag. In addition, the segregation occurs in the slag skin forming process. This is another reason causing the composition change of electroslag.
基金Project(S2013040015492)supported by the Natural Science Foundation of Guangdong Province,ChinaProject(2007AA03Z240)supported by Hi-tech Research and Development Program of China
文摘Ru O2·n H2O film was deposited on tantalum foils by electrodeposition and heat treatment using Ru Cl3·3H2O as precursor.Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·n H2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2h, RuO2·n H2O electrode surface gains mass of2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly20% with voltage scan rate increasing from 5 to 250 m V/s.
基金supported by National Natural Science Foundation of China(Nos.61405147,51375348)the Scientific Research Fund of Zhejiang Provincial Education Department,China(No.Y201430387)
文摘The concentration of elements in molten metal of AZ31 magnesium alloy after long pulsed Nd：YAG laser processing was quantitatively analyzed by using calibration-free laser-induced breakdown spectroscopy （CF-LIBS）. The composition change in AZ31 magnesium alloy under different laser pulse width was also investigated. The experimental results showed that CF-LIBS can obtain satisfactory quantitative or semi-quantitative results for matrix or major elements, while only qualitative analysis was possible for minor or trace elements. Moreover, it is found that the chemical composition of molten metal will change after laser processing. The concentration of magnesium in molten metal is lower than that present in the base metal. The Mg loss increases with an increase of pulse width in the laser processing. This result shows that the selective vaporization of different elements is affected by the pulse width during laser processing.
基金the National Natural Science Foundation of China[grant numbers 52203038,52173036 and 52073107]the National Key Technology R&D Program of China[grant number 2022YFC3901904,2022YFC3901903,and 2020YFB1709301]the Central University Basic Research Fund of China[grant number 2021XXJS035].
文摘The severe dependence of traditional phase change materials(PCMs)on the temperature-response and lattice deficiencies in versatility cannot satisfy demand for using such materials in complex application scenarios.Here,we introduced metal ions to induce the self-assembly of MXene nanosheets and achieve their ordered arrangement by combining suction filtration and rapid freezing.Subsequently,a series of MXene/K^(+)/paraffin wax(PW)phase change composites(PCCs)were obtained via vacuum impregnation in molten PW.The prepared MXene-based PCCs showed versatile applications from macroscale technologies,successfully transforming solar,electric,and magnetic energy into thermal energy stored as latent heat in the PCCs.Moreover,due to the absence of binder in the MXene-based aerogel,MK3@PW exhibits a prime solar-thermal conversion efficiency(98.4%).Notably,MK3@PW can further convert the collected heat energy into electric energy through thermoelectric equipment and realize favorable solar-thermal-electric conversion(producing 206 mV of voltage with light radiation intensity of 200 mw cm^(−2)).An excellent Joule heat performance(reaching 105℃with an input voltage of 2.5 V)and responsive magnetic-thermal conversion behavior(a charging time of 11.8 s can achieve a thermal insulation effect of 285 s)for contactless thermotherapy were also demonstrated by the MK3@PW.Specifically,as a result of the ordered arrangement of MXene nanosheet self-assembly induced by potassium ions,MK3@PW PCC exhibits a higher electromagnetic shielding efficiency value(57.7 dB)than pure MXene aerogel/PW PCC(29.8 dB)with the same MXene mass.This work presents an opportunity for the multi-scene response and practical application of PCMs that satisfy demand of next-generation multifunctional PCCs.
基金supported by the National Natural Science Foundation of China (No.82304722)Hubei Provincial Natural Science Foundation of China (No.2023AFD154).
文摘Atractylodis Rhizoma,a traditional Chinese medicine with an extensive history of treating gastrointestinal disorders and other diseases,undergoes various processing methods in China to enhance its therapeutic efficacy for specific conditions.However,a comprehensive report detailing the changes in chemical composition and pharmacological effects due to these processing methods is currently lacking.This article provides a systematic review of the commonly employed processing techniques for Atractylodis Rhizoma,including raw Atractylodis Rhizoma(SCZ),bran-fried Atractylodis Rhizoma(FCZ),deep-fried Atractylodis Rhizoma(JCZ),and rice water-processed Atractylodis Rhizoma(MCZ).It examines the alterations in chemical constituents and pharmacological activities resulting from these processes and elucidates the mechanisms of action of the primary components in the various processed forms of Atractylodis Rhizoma in the treatment of gastrointestinal diseases.
文摘Graphene-based phase change composites hold significant potential for solar energy utilization,but their poor thermal conductivity hinders their practical applications.In this work,an air-dried graphene skele-ton(AGS)with excellent thermal conductivity enhancement efficiency was constructed by the ice tem-plating method and syneresis,and the air-dried graphene phase change composite(AGP)was subse-quently obtained through vacuum-impregnating n-Docosane(C22)into AGS.The syneresis effectively re-duced the phonon scattering between graphene sheets within AGS and increased the density of AGS to 0.1701 g/cm3.Therefore,with a graphene skeleton loading of 23.82 wt.%,AGP exhibited excellent thermal conductivity of 9.867 W/(m K),outstanding electrical conductivity of 68.08 S/cm,and remarkable shape stability.Additionally,AGP demonstrated a melting enthalpy of 188.5 J/g and an outstanding solar-thermal conversion efficiency of 93.98%,showing enormous potential for the utilization of solar energy.
基金This work was supported in part by Tsinghua University-Zhuhai Huafa Industrial Share Company Joint Institute for Architecture Optoelectronic Technologies(JIAOT KF202204)in part by STI 2030—Major Projects under Grant 2022ZD0209200+2 种基金in part by National Natural Science Foundation of China under Grant 62374099,Grant 62022047in part by Beijing Natural Science-Xiaomi Innovation Joint Fund under Grant L233009in part by the Tsinghua-Toyota JointResearch Fund,in part by the Daikin-Tsinghua Union Program,in part sponsored by CIE-Tencent Robotics XRhino-Bird Focused Research Program.
文摘Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device level,which results in a gap to real applications.Here,we propose a controllable thermal rectification design towards building applications through the direct adhesion of composite thermal rectification material(TRM)based on PCM and reduced graphene oxide(rGO)aerogel to ordinary concrete walls(CWs).The design is evaluated in detail by combining experiments and finite element analysis.It is found that,TRM can regulate the temperature difference on both sides of the TRM/CWs system by thermal rectification.The difference in two directions reaches to 13.8 K at the heat flow of 80 W/m^(2).In addition,the larger the change of thermal conductivity before and after phase change of TRM is,the more effective it is for regulating temperature difference in two directions.The stated technology has a wide range of applications for the thermal energy control in buildings with specific temperature requirements.
基金supported by the Natural Science Foundation of Hunan Province(No.2024JJ4059)Changsha Outstanding Innovative Youth Training Program(No.kq2306010)+1 种基金National Natural Science Foundation of China(No.52176093)the Central South University Innovation-Driven Research Programme(No.2023CXQD055).
文摘Phase change materials(PCMs)are widely considered as promising energy storage materials for solar/electro-thermal energy storage.Nevertheless,the inherent low thermal/electrical conductivities of most PCMs limit their energy conversion efficiencies,hindering their practical applications.Herein,we fabricate a highly thermally/electrically conductive solid-solid phase change composite(PCC)enabled by forming aligned graphite networks through pressing the mixture of the trimethylolethane and porous expanded graphite(EG).Experiments indicate that both the thermal and electrical conductivities of the PCC increase with increasing mass proportion of the EG because the aligned graphite networks establish highly conductive pathways.Meanwhile,the PCC4 sample with the EG proportion of 20wt%can achieve a high thermal conductivity of 12.82±0.38W·m^(-1)·K^(-1)and a high electrical conductivity of 4.11±0.02S·cm^(-1)in the lengthwise direction.Furthermore,a solar-thermal energy storage device incorporating the PCC4,a solar selective absorber,and a highly transparent glass is developed,which reaches a high solar-thermal efficiency of 77.30±2.71%under 3.0 suns.Moreover,the PCC4 can also reach a high electro-thermal efficiency of 91.62±3.52%at a low voltage of 3.6V,demonstrating its superior electro-thermal storage performance.Finally,stability experiments indicate that PCCs exhibit stabilized performance in prolonged TES operations.Overall,this work offers highly conductive and cost-effective PCCs,which are suitable for large-scale and efficient solar/electro-thermal energy storage.
基金supported by The Youth Project of the National Natural Science Foundation of China(No.82204623)Key scientific research projects in universities in Anhui Province(No.2022AH050471)+1 种基金Young Science and Technology Talents Cultivation Program of Anhui University of Traditional Chinese Medicine(No.2021qnyc04)Scientific Research Team Program of Anhui Colleges and Universities(No.2022AH010036).
文摘The theory of“Salt-processing enhancing drug into kidney meridian”was firstly put forward by Chen Jiamu,a medical doctor of Xin’an,in“Enlightening Primer of Materia Medica”.This theory integrates the theory of the five elements of Chinese medicine that the five flavors enter into the five viscera,and forms the theory of the role of the auxiliary materials of Chinese medicine concoctions.This theory is an important guiding significance for the clinical use of raw and cooked Chinese medicine tablets.At present,there are more studies on the theory of“Salt-processing enhancing drug into kidney meridian”in the literature,mainly focusing on the chemical composition,efficacy changes and the concoction mechanism of salt products of traditional Chinese medicines before and after salt preparation.There are relatively few review papers on the theory of“Salt-processing enhancing drug into kidney meridian”from the perspectives of auxiliary salt and attribution of meridians.In this paper,through reviewing relevant ancient books and literature,and on the basis of the previous review articles,this paper centers on the auxiliary salt,and conducts in-depth excavation and elaboration in terms of its sources,types,and the historical evolution of the salt production method.From the perspective of categorization,focusing on the core theory of“Kidney stores essence,governing reproduction,bone and generating marrow,water and brain”,we summarize the changes in efficacy before and after the salt preparation of kidney tonic traditional Chinese medicines,the changes in external and internal constituents as well as the scientific connotation of the concocting mechanism behind the effect-constituent changes.The scientific connotation of the concoction theory of“Salt-processing enhancing drug into kidney meridian”was initially elucidated,providing a new reference model for the study of the theory of Chinese medicine concoction attribution.
基金supported by the Program for New Century Excellent Talents in University (Grant No. NCET-08-828)the Program for the China Geological Survey (No. 1212011120323)the Fundamental Research Funds for the Central Universities (No. 2011YXL003)
文摘A new potassium nitrate （KNO3）]diatomite shape-stabilized composite phase change material （SS- CPCM） was prepared by the mixing and sintering method. KNO3 served as the phase change material （PCM） for thermal energy storage, while diatomite acted as the carrier matrix to provide the structural strength and prevent the leakage of PCM. It was found that KNO3 could be retained 65 wt% into pores and on surfaces of diatomite without the leakage of melted KNO3 from the SS-CPCM. The calculated filling rate of molten KNO3 that could enter into the disc-like shape pore of diatomite verified the scanning elec- tronic microscopy images of SS-CPCM. X-ray diffraction and Fourier transform infrared spectroscopy results showed that no reaction occurred between KNO3 and diatomite, performing good compatibility. Accord- ing to the differential scanning calorimetry results, after 50 thermal cycles, the phase change temperatures for melting and freezing of SS-CPCM with 65 wt% KNO3 were changed from 330.23 ℃ and 332.90 ℃ to 330.11 ℃ and 332.84 ℃ and corresponding latent heats varied from 60.52 J/g and 47.30 J/g to 54.64 J/g and 41.25 J/g, respectively. The KNO3/diatomite SS-CPCM may be considered as a potential storage media in solar power plants for thermal energy storage.
文摘Electronic devices generate heat during operation and require efficient thermal management to extend the lifetime and prevent performance degradation.Featured by its exceptional thermal conductivity,graphene is an ideal functional filler for fabricating thermally conductive polymer composites to provide efficient thermal management.Extensive studies have been focusing on constructing graphene networks in polymer composites to achieve high thermal conductivities.Compared with conventional composite fabrications by directly mixing graphene with polymers,preconstruction of three-dimensional graphene networks followed by backfilling polymers represents a promising way to produce composites with higher performances,enabling high manufacturing flexibility and controllability.In this review,we first summarize the factors that affect thermal conductivity of graphene composites and strategies for fabricating highly thermally conductive graphene/polymer composites.Subsequently,we give the reasoning behind using preconstructed three-dimensional graphene networks for fabricating thermally conductive polymer composites and highlight their potential applications.Finally,our insight into the existing bottlenecks and opportunities is provided for developing preconstructed porous architectures of graphene and their thermally conductive composites.
基金supported by the National Key Technology R&D Program of China (Grant Nos. 2020YFB1709301 and 2020YFB1709304)the National Natural Science Foundation of China (No. 52173036 and 52073107)+3 种基金the Central University Basic Research Fund of China (Grants 2021XXJS035)the Innovation and Talent Recruitment Base of New Energy Chemistry and Device (Grants B21003)the Opening Project of Key Laboratory of Polymer Processing Engineering (South China University of Technology),Ministry of Education (Grant No. KFKT2002)fund from Henan University of Science and Technology (2020-RSC02)
文摘The development of functional composites with excellent thermal management capabilities and electro-magnetic interference(EMI)shielding has become extremely urgent for keeping up with the continuous improvement of the operating speed and efficiency for electronic equipment.In this study,the biolog-ical wood-derived porous carbon(WPC)was determined as the supporting material to encapsulating polyethylene glycol(PEG),and a series of WPC/PEG/Fe_(3)O_(4) phase change composites(PCCs)with excel-lent shape stability,EMI shielding and thermal management capabilities were prepared via a simple vac-uum impregnation method.The Fe_(3)O_(4) magnetic particles modified PCCs have greatly improved the EMI shielding effectiveness(SE).The EMI SE of WP-4(7.5 wt.% Fe_(3)O_(4) in PEG)can be up to 55.08 dB between 8.2−12.4 GHz,however,the WP-0 without Fe_(3)O_(4) addition is only 40.08 dB.Meanwhile,the absorption ratio of electromagnetic waves(EMW)has also increased from 75.02%(WP-0)to 85.56%(WP-4),which effectively prevents secondary pollution.In addition,after wrapping a thin layer of polydimethylsiloxane resin(PDMS),the obtained WP-4 can maintain a high heat storage capacity(109.52 J/g)and good wa-ter stability.In short,the prepared WPC/PEG/Fe_(3)O_(4) PCCs have great potential application value in the thermal management and electromagnetic shielding requirements for electronic devices.
基金This research was funded by the National Natural Science Foundation of China(51879166)the Open Fund of the State Key Laboratory of Frozen Soil Engineering of China(SKLFSE201909).
文摘Phase change materials(PCMs)can store large amounts of energy in latent heat and release it during phase changes,which could be used to improve the freeze-thaw performance of soil.The composite phase change material was prepared with paraffin as the PCM and 8%Class C fly ash(CFA)as the supporting material.Laboratory tests were conducted to reveal the influence of phase change paraffin composite Class C fly ash(CFA-PCM)on the thermal properties,volume changes and mechanical properties of expansive soil.The results show that PCM failed to establish a good improvement effect due to leakage.CFA can effectively adsorb phase change materials,and the two have good compatibility.CFA-PCM reduces the volume change and strength attenuation of the soil,and 8 wt.%PCM is the optimal content.CFA-PCM turns the phase change latent heat down of the soil and improves its thermal stability.CFA-PCM makes the impact small of freeze-thaw on soil pore structure damage and improves soil volume change and mechanical properties on a macroscopic scale.In addition,CFA-8 wt.%PCM treated expansive soil has apparent advantages in resisting repeated freeze-thaw cycles,providing a reference for actual engineering design.
基金supported by the National Natural Science Foundation of China (Nos. 50876058 and 20876042)Program for New Century Excellent Talents in University(NCET-10-883)Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning
文摘Oleylamine （G18） and octanol （G8） were grafted onto the surfaces of the multi-walled carbon nanotubes （CNTs）. The grafted CNTs were dispersed into palmitic acid （PA） and paraffin wax （PW） to prepare phase change composites. The heat storage/retrieval experiments showed that the composites kept stable after repeating melting and solidification for 80 times. The structure of the G18-CNT/PA and G8-CNT/PA was homogenous compared with the pristine CNT （P-CNT）/PA. The latent heat capacity （Ls） of solid liquid phase change of G18-CNT/PW was higher than that of PW while those of the G8-CNTI/PW and P-CNT/PW were lower than that of PW. Compared with PA, all PA based composites with both P-CNTs and grafted CNTs decreased Ls evidently. The Ls values of GI8-CNT composites in both matrices were higher than that of the counterparts of G8-CNT. The thermal conductivities of all the PA based composites in the study were higher than that of PA, as well as those of all the PW based composites. However, the thermal conductivities of the GI8-CNT composites in both matrixes were lower than those of the G8-CNT composites in both matrixes at all measured temperatures.
基金Information on site history and assistance with site logistics were provided by Barbara Benner and the Bureau of Land Management.Jessica DaBell assisted with field work,Jean Caldwell with GIS analysis,and Loveday Conquest with statistical analysis.Funding for the 2010 re-measurement of these plots was provided by the Joint Fire Science Program under Project JFSP 08-1-5-20.
文摘Introduction:Communities change over time due to disturbances,variations in climate,and species invasions.Biological soil crust communities are important because they contribute to erosion control and nutrient cycling.Crust types may respond differently to changes in environmental conditions:single-celled organisms and bryophytes quickly recover after a disturbance,while lichens are slow growing and dominate favorable sites.Community change in crusts has seldom been assessed using repeated measures.For this study,we hypothesized that changes in crust composition were related to disturbance,topographic position,and invasive vegetation.Methods:We monitored permanent plots in the Columbia Basin in 1999 and 2010 and compared changes in crust composition,cover,richness,and turnover with predictor variables of herbivore exclosure,elevation,heat load index,time since fire,presence of an invasive grass,and change in cover of the invasive grass.Results:Bryophytes were cosmopolitan with high cover.Dominant lichens did not change dramatically.Indicator taxa differed by monitoring year.Bryophyte and total crust cover declined,and there was lower turnover outside of herbivore exclosures.Lichen cover did not change significantly.Plots that burned recently had high turnover.Increase in taxon richness was correlated with presence of an invasive grass in 1999.Change in cover of the invasive grass was positively related to proportional loss and negatively related to gain.Conclusions:Composition and turnover metrics differed significantly over 11 years,though cover was more stable between years.This study can be a baseline for assessing change in crust composition due to anthropogenic influences.
文摘Lignin is a polymer of phenylpropanoid compounds formed through a complex biosynthesis route, represented by a metabolic grid for which most of the genes involved have been sequenced in several plants, mainly in the model-plants Arabidopsis thaliana and Populus. Plants are exposed to different stresses, which may change lignin content and composition. In many cases, particularly for plant-microbe interactions, this has been suggested as defence responses of plants to the stress. Thus, understanding how a stressor modulates expression of the genes related with lignin biosynthesis may allow us to develop study-models to increase our knowledge on the metabolic control of lignin deposition in the cell wall. This review focuses on recent literature reporting on the main types of abiotic and biotic stresses that alter the biosynthesis of lignin in plants.
基金supported by DST SB/YS/LS-205/2013CSIR(09/560(0015)/2011-EMRI),Govt.of India
文摘We studied forest vegetation at Lata-Tolma- Phagti, a protected area and part of Nanda Devi Biosphere Reserve in the western Himalaya. We analyzed community composition, population structure, regeneration patterns, and projected development of future compositional patterns. We sampled ten 10 x 10 m quadrat for tree species in each of 30 forest stands. We sampled shrubs in ten 5 x 5 m quadrat, and herbs in twenty 1 x 1 m quadrat within each forest stand. We recorded 248 plant species from 8 forest communities. Broadly the demographic profiles at study sites exhibited progressive structures suggesting long term persistence of the communities/species. Density--diameter distribution revealed greater proportions of seedlings and a significant decline （P 〈 0.05） in the proportion of trees in older age/size classes. Of the 23 recorded tree species, 13.0 % showed good, 52.2 % fair, 26.1% poor and 8.7 % no regeneration. Differences in regeneration by species are indicative of future foreststructure and dynamics. Assessment of changes in structure of forest types provides baseline data for development of priorities for conservation of other representative land- scapes in the reserve as well as in the Himalaya.
