The unparalleled energy density has granted lithium-sulfur batteries(LSBs)with attractive usages.Unfortunately,LSBs still face some unsurpassed challenges in industrialization,with polysulfides shuttling,dendrite grow...The unparalleled energy density has granted lithium-sulfur batteries(LSBs)with attractive usages.Unfortunately,LSBs still face some unsurpassed challenges in industrialization,with polysulfides shuttling,dendrite growth and thermal hazard as the major problems triggering the cycling instability and low safety.With the merit of convenience,the method of designing functional separator has been adapted.Concretely,the carbon aerogel confined with CoS_(2)(CoS_(2)-NCA)is constructed and coated on Celgard separator surface,acquiring CoS_(2)-NCA modified separator(CoS_(2)-NCA@C),which holds the promoted electrolyte affinity and flame retardance.As revealed,CoS_(2)-NCA@C cell gives a high discharge capacity 1536.9 mAh/g at 1st cycle,much higher than that of Celgard cell(987.1 mAh/g).Moreover,the thermal runaway triggering time is dramatically prolonged by 777.4 min,corroborating the promoted thermal safety of cell.Noticeably,the higher coulombic efficiency stability and lower overpotential jointly confirm the efficacy of CoS_(2)-NCA@C in suppressing the lithium dendrite growth.Overall,this work can provide useful inspirations for designing functional separator,coping with the vexing issues of LSBs.展开更多
The retarding effect of protein retarder on phosphorus building gypsum(PBG)and desulfurization building gypsum(DBG)was investigated,and the results show that protein retarder for DBG can effectively prolong the settin...The retarding effect of protein retarder on phosphorus building gypsum(PBG)and desulfurization building gypsum(DBG)was investigated,and the results show that protein retarder for DBG can effectively prolong the setting time and displays a better retarding effect,but for PBG shows a poor retarding effect.Furthermore,the deterioration reason of the retarding effect of protein retarder on PBG was investigated by measuring the pH value and the retarder concentration of the liquid phase from vacuum filtration of PBG slurry at different hydration time,and the measure to improve the retarding effect of protein retarding on PBG was suggested.The pH value of PBG slurry(<5.0)is lower than that of DBG slurry(7.8-8.5).After hydration for 5 min,the concentration of retarder in liquid phase of DBG slurry gradually decreases,but in liquid phase of PBG slurry continually increases,which results in the worse retarding effect of protein retarder on PBG.The liquid phase pH value of PBG slurry can be adjusted higher by sodium silicate,which is beneficial to improvement in the retarding effect of the retarder.By adding 1.0%of sodium silicate,the initial setting time of PBG was efficiently prolonged from 17 to 210 min,but little effect on the absolute dry flexural strength was observed.展开更多
Based on a large number of orthogonal tests and theoretical analyses, the retarding mortar which meets the requirements of retard-bonded prestressed concrete was prepared. Initial setting time of the retarding mortar ...Based on a large number of orthogonal tests and theoretical analyses, the retarding mortar which meets the requirements of retard-bonded prestressed concrete was prepared. Initial setting time of the retarding mortar may vary from several hours to 15 d at 5 ℃-35 ℃ due to quantities and average curing temperature. And its 28 d compressive strength is above 35 MPa. Thus the influence of quantities on setting time and 28 d compressive strength, and the relationship between setting time and average curing temperature were investigated. The optimum quantities were obtained by studying the interaction of admixtures, and the retarding mechanism was discussed. Based on 52 retard-bonded prestressed strands by manual work from 24 retard-bonded prestressed concrete T-beams, static friction drag, change factor κ and friction factor μ were obtained from the test when retard-bonded prestressed strands were tensioned. Application of the retarding mortar will be vast in practical concrete projects.展开更多
A combination of the rainfall-runoff module of the Xin’anjiang model, the Muskingum routing method, the water stage simulating hydrologic method, the diffusion wave nonlinear water stage method, and the real-time err...A combination of the rainfall-runoff module of the Xin’anjiang model, the Muskingum routing method, the water stage simulating hydrologic method, the diffusion wave nonlinear water stage method, and the real-time error correction method is applied to the real-time flood forecasting and regulation of the Huai River with flood diversion and retarding areas. The Xin’anjiang model is used to forecast the flood discharge hydrograph of the upstream and tributary. The flood routing of the main channel and flood diversion areas is based on the Muskingum method. The water stage of the downstream boundary condition is calculated with the water stage simulating hydrologic method and the water stages of each cross section are calculated from downstream to upstream with the diffusion wave nonlinear water stage method. The input flood discharge hydrograph from the main channel to the flood diversion area is estimated with the fixed split ratio of the main channel discharge. The flood flow inside the flood retarding area is calculated as a reservoir with the water balance method. The faded-memory forgetting factor least square of error series is used as the real-time error correction method for forecasting discharge and water stage. As an example, the combined models were applied to flood forecasting and regulation of the upper reaches of the Huai River above Lutaizi during the 2007 flood season. The forecast achieves a high accuracy and the results show that the combined models provide a scientific way of flood forecasting and regulation for a complex watershed with flood diversion and retarding areas.展开更多
In the Tibet ancient buildings, there are large amounts of combustible decorative textiles that pose great potential fire hazards. Some typical textile samples were collected from the Potala Palace. Their combustion p...In the Tibet ancient buildings, there are large amounts of combustible decorative textiles that pose great potential fire hazards. Some typical textile samples were collected from the Potala Palace. Their combustion properties were analyzed by UL 94 Vertical Burning test and Limiting Oxygen Index test. The effects of plateau climate on combustion properties, an important fact required to be considered in the flame retarding design for combustible textiles, were preliminarily compared via test data in the plain and those in the plateau. Based on the foregoing analyses, some thoughts were presented on the clean and feasible flame retarding means for the decorative textiles due to their special applications in Tibet, in ancient buildings and in plateau climate. The fire resistance, weather resistance, UV resistance, endurance, ornamentation and religious performances for these textiles must be taken into considerations comprehensively in the designs.展开更多
The synthesis of reaction flame retarding unsaturated polyester resin and the flame retarding mechanism are investigated.By taking the synthesis flame retarding unsaturated polyester resin as a base material,glass fib...The synthesis of reaction flame retarding unsaturated polyester resin and the flame retarding mechanism are investigated.By taking the synthesis flame retarding unsaturated polyester resin as a base material,glass fibers as reinforced material,under the condition of adding graphite or carbon black respectively,the composites were manufactured.The flame retarding and antistatic properties are also studied.In the experiment,bromide-bearing flame retarding resin decomposed under a high temperature.Compound HBr was set out and retarded or stopped the flame.High concentration of HBr gas wall was formed between gas and solid phrases,which decreased flame.The results show that antistatic property of carbon black is higher than that of graphite.Adding a threshed value of 1% carbon black into composite,the antistatic property is at its highest value.展开更多
The combustion mechanisms of PP / Viscose blend fabrics are briefly discussed, and the factors affecting flame retarding(FR) effect are analyzed. Apart from this, the choice of processes of FR finish is also discussed...The combustion mechanisms of PP / Viscose blend fabrics are briefly discussed, and the factors affecting flame retarding(FR) effect are analyzed. Apart from this, the choice of processes of FR finish is also discussed in this paper. Other factors such as coating add-on, curing temperature and time are studied too. The results show that the factors above all have different extent of influence upon FR effect.展开更多
A multi-channel retarding field analyzer（MC-RFA） including two RFA modules and two Langmuir probes to measure the ion and electron temperature profiles within the scrape-off layer was developed for investigations of...A multi-channel retarding field analyzer（MC-RFA） including two RFA modules and two Langmuir probes to measure the ion and electron temperature profiles within the scrape-off layer was developed for investigations of the interplay between magnetic topology and plasma transport at the plasma boundary.The MC-RFA probe for the stellarator W7-X and first measurements at the tokamak EAST was designed.The probe head allows simultaneous multichannel ion temperature as well as for electron temperature measurements.The usability for radial correlation measurements of the measured ion currents is also given.展开更多
Radial profiles of the ion temperature,Ti,have been measured by a double-sided retarding field analyzer（RFA） in the scrape-off layer（SOL） of the J-TEXT tokamak（R = 105 cm,r = 25-29 cm,Bt = 1.8-2.0 T,Ip = 120-180 ...Radial profiles of the ion temperature,Ti,have been measured by a double-sided retarding field analyzer（RFA） in the scrape-off layer（SOL） of the J-TEXT tokamak（R = 105 cm,r = 25-29 cm,Bt = 1.8-2.0 T,Ip = 120-180 kA,ne =（2-2.5） × 10^19 m^-3）.Strongly declining Ti profiles in the SOL have been found.The different e-folding lengths,At,of the Ti profiles in two experimental configurations with different magnetic connection lengths,Lc,reveal that a longer Lc results in weaker parallel energy transport and longer At.In similarity with the particle transport across the SOL,At is approximately proportional to the square root of Lc.Additionally,the poloidal asymmetry has been identified with enhanced ion energy transport across the SOL on the low-field side.展开更多
The primary objective of this research was to determine optimum dosage of mixing concrete containing plasticizers and fly ash, consistent with desirable structural grade concrete properties. Factorial tests were also ...The primary objective of this research was to determine optimum dosage of mixing concrete containing plasticizers and fly ash, consistent with desirable structural grade concrete properties. Factorial tests were also conducted to investigate the four main factors： water-cementing materials ratio, water content, content of superplasticizers （SP） and fly ash content. It was found that the requirement for setting time played the dominant role in shrinkage and anti-cracking, and fly ash played a critical role in workability and reducing heat of hydration but showed insignificant effects on slump, early strength and initial setting time of concrete.展开更多
N-2000 is an admixture for concrete,with a low slump loss,high range water-reducing ratio and long-time retarding.The N-2000 is made up of naphthalene-sulfonic-maldehyde polycondensation(NSMP)and ATMP.Its characterist...N-2000 is an admixture for concrete,with a low slump loss,high range water-reducing ratio and long-time retarding.The N-2000 is made up of naphthalene-sulfonic-maldehyde polycondensation(NSMP)and ATMP.Its characteristic results from the synergistic effects of NSMP and ATMP.The results show that when 0.7%-1.2%of N-2000 is added to concrete(by mass of cement),the water reducing ratio is up to 20%-30%,and the slump of fresh concrete can be retained for 2 hours without significant loss.N-2000 can not only improve the workability of fresh concrete but also increase the strength of the hardened concrete,especially early strength.It is also proved to have a good compatibility with various cements.展开更多
An anomalous phenomenon was observed in the retarding potential analyzer （RPA） measurements of the energy of the ion beam from an 8 cm argon ion source. The current-voltage （Ⅰ- Ⅴ） curve, which should theoretical...An anomalous phenomenon was observed in the retarding potential analyzer （RPA） measurements of the energy of the ion beam from an 8 cm argon ion source. The current-voltage （Ⅰ- Ⅴ） curve, which should theoretically descend, went up as the ion retarding potential was increased. Various explanations, such as the Townsend discharge theory and secondary electron emission etc. were proposed but denied by the theory application condition or the experiment results. An angle of about -10° was found between the axes of the ion beam and the RPA according to the contours of the ion beam density and direction. The particle simulation and experiment of the sum of the collector and wall current were conducted at different incident ion angles. The trends of the Ⅰ- Ⅴ curve in simulation results conformed with the experimental results in most cases. The ion trajectories were simulated at different retarding potentials with an incident angle of -10°. According ：to these results, the reason for the anomalous phenomenon is that when there is a specific angle between the axes of the ion beam and the RPA, more ions are repelled from the vicinity of the ion retarding grid to avoid striking on the grid as the ion retarding potential increases. These redundant ions reach the plate and thus lead to the formation of an ascending Ⅰ- Ⅴ curve.展开更多
Flame-retardant composites with high electromagnetic interference(EMI)shielding performance are desirable for electronic device packaging.Despite great potential of MXene for high EMI,it still remains a great challeng...Flame-retardant composites with high electromagnetic interference(EMI)shielding performance are desirable for electronic device packaging.Despite great potential of MXene for high EMI,it still remains a great challenge to develop high-performance flame-retardant polymer/MXene composites with excellent EMI shielding effectiveness because of the poor oxidative stability of MXene.Herein,phosphorylated MXene/polypropylene(PP)composites are prepared by coating phosphorylated MXene on PP fabric followed by spraying polyethylenimine(PEI)and hot-pressing.The phosphorylated MXene proves to be more durable against oxidation than pure MXene due to the protection effect of polyphosphates.Upon hot-pressing,melted PP fibers are fused together at their contact points and thus as-prepared composites are bi-continuous with two interpenetrating phases.The composites show significantly improved thermal stability and flame retardancy relative to pure PP,with a low total heat release(THR)of 3.7 kJ/g and a heat release rate(HRR)of 50.0 W/g,which are reduced by 78%and 87%,respectively.In addition,the composites exhibit a high electrical conductivity of~36,700 S/m and an EMI shielding performance of~90 d B over the whole frequency range of 8–12 GHz with a thickness of~400μm.The as-developed PP/MXene composites hold great promise for reliable protection of next-generation electronic devices working in complex environments.展开更多
Renewable and biodegradable polylactide (PLA) has excellent mechanical strength but is highly flammable which restricts its practical applications. Many phosphorus/nitrogen (P/N)-based flame retardants are ef- fective...Renewable and biodegradable polylactide (PLA) has excellent mechanical strength but is highly flammable which restricts its practical applications. Many phosphorus/nitrogen (P/N)-based flame retardants are ef- fective in PLA, but their high addition loading usually decreases the mechanical strength of the PLA bulk. For polyphosphoramides, despite high fire-retardant efficiency, their chemical synthesis often generates chemical wastes as byproducts. Herein, we report an atom-economic and highly efficient oligomeric P/N fire retardant (APN) prepared using a mild Michael addition polymerization with no byproducts. Using only 3 wt% APN, the resulting PLA exhibits desired fire retardancy including a UL-94 V-0 rating and a limiting oxygen index of 37.6%. Furthermore, the toughness of the fire-retardant PLA increases by 85% compared to pure PLA, with both tensile strength and thermal stability preserved. This work offers an atom-economic strategy for synthesizing highly efficient P/N fire retardants for use in the creation of fire-resistant PLA with robust mechanical properties.展开更多
An organophosphorus-based diamine has been synthesized and used as a curing and flame retarding bifunctional agent for epoxy resins.This phosphorodiamidate functions not only as a crosslinking materials in the Epon 82...An organophosphorus-based diamine has been synthesized and used as a curing and flame retarding bifunctional agent for epoxy resins.This phosphorodiamidate functions not only as a crosslinking materials in the Epon 828 epoxy resin curing process but also as a fire retarding compound to produce thin films or composites upon curing.This phosphorus-containing reactive amine was synthesized via condensation of phenyphosphonic dichloride with ethylenediamine in the presence of sodium methoxide.The product was then purified and later characterized by NMR and FTIR spectroscopy as well as MALDI-TOF mass spectrometry.Kinetics studies of the curing reaction of the phosphorodiamidate were carried out in comparison with the non-phosphorus containing ethylenediamine reference crosslinking agent.Thermal stability of the cured epoxy ware investigated by thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC).Moreover,flame retardant properties of the obtained materials was investigated by limiting oxygen index(LOI)measurements as well as the UL-40 method.The obtained results show that epoxy resin cured with phosphorodiamidate possesses higher thermostability compared to the epoxy cured with the regular ethylenediamine counterpart.This is evident by higher amount of char formed upon burning.More importantly,the LOI value of 27 was observed in the phosphorodiamidate-cured epoxy resin compared with LOI of 20 of the epoxy resin cured with ethylenediamine where no phosphorus was present.The UL-94 highest rating of V-0 materials was obtained with only about 2-3 wt%of the phosphorus element.The chemistry,curing kinetics,and thermal properties of these new epoxy formulations are discussed.展开更多
Polymeric organic battery materials are promising alternatives to the transition-metal-based ones owing to their enriched chemistries. However, the flammability of organic compounds brings in serious concern on batter...Polymeric organic battery materials are promising alternatives to the transition-metal-based ones owing to their enriched chemistries. However, the flammability of organic compounds brings in serious concern on battery safety. In addition to use flame-retarding electrolyte/electrolyte additives or battery separators,flame retardancy can readily be achieved through the integration of flame-retarding unit into the polymer backbone, imparting the flame retardancy permanently. The as-designed polymer based on phenothiazine shows significantly shortened self-extinguished time without deteriorating its intrinsic thermodynamic and electrochemical properties. Moreover, two electron per phenothiazine molecule is realized for the first time in a highly reversible manner with discharge voltages of 3.52 V and 4.16 V versus Li+/Li and an average capacity of ca. 120 mAh g-1 at a current rate of 2 C. The origin of the reversibility is investigated through density functional theory(DFT) calculations. These findings address the importance of molecular design for safer and more stable organic materials for batteries.展开更多
High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polym...High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polymer/MXene nanocom-posites remains challenging owing to the limited flame-retardant properties of MXene itself.This study prepared a novel MXene@Ag@PA hybrid material via radiation modification and complexation reaction.This material was used to further enhance the key properties of ethylene-vinyl acetate(EVA),such as its mechanical properties,thermal conductivity,flame retardancy,and electromagnetic shielding.The addition of two parts of this hybrid material increased the thermal conduc-tivity of EVA by 44.2%and reduced its peak exothermic rate during combustion by 30.1%compared with pure EVA.The material also significantly reduced smoke production and increased the residue content.In the X-band,the electromagnetic shielding effectiveness of the EVA composites reached 20 dB.Moreover,the MXene@Ag@PA hybrid material could be used to further enhance the mechanical properties of EVA composites under electron-beam irradiation.Thus,this study contributes to the development of MXene-based EVA advanced materials that are fire-safe,have high strength,and exhibit good electromagnetic shielding performance for various applications.展开更多
Depolarizing behavior is commonly observed in most natural samples.For this reason,optical tools measuring the differences in depolarization response among spatially separated structures are highly useful in a wide ra...Depolarizing behavior is commonly observed in most natural samples.For this reason,optical tools measuring the differences in depolarization response among spatially separated structures are highly useful in a wide range of imaging applications for enhanced visualization of structures,target identification,etc.One commonly used tool for depolarizing discrimination is the so-called depolarizing spaces.In this article,we exploit the combined use of two depolarizing spaces,the indices of polarization purity(IPP)and polarizance–reflection–transformation(PRT)spaces,to improve the capability of optical systems to identify polarization–anisotropy depolarizers.The potential of these spaces to discriminate among different depolarizers is first studied from a series of simulations by incoherently adding diattenuations or retarders,with some control parameters emulating samples in nature.The simulated results demonstrate that the proposed methods are capable of increasing differences among depolarizers beyond other well-known techniques.Experimentally,validation is provided by conducting diverse phantom experiments of easy interpretation and mimicking the stated simulations.As a useful application of our approach,we developed a model able to retrieve intrinsic microscopic information of samples from macroscopic polarimetric measurements.The proposed methods enable non-invasive,straightforward,macroscopic characterization of depolarizing samples,and may be of interest for enhanced visualization of samples in multiple imaging scenarios.展开更多
In recent decades,annual urban fire incidents,including those involving ancient wooden buildings burned,transportation,and solar panels,have increased,leading to significant loss of human life and property.Addressing ...In recent decades,annual urban fire incidents,including those involving ancient wooden buildings burned,transportation,and solar panels,have increased,leading to significant loss of human life and property.Addressing this issue without altering the surface morphology or interfering with optical behavior of flammable materials poses a substantial challenge.Herein,we present a transparent,low thickness,ceramifiable nanosystem coating composed of a highly adhesive base(poly(SSS1-co-HEMA1)),nanoscale layered double hydroxide sheets as ceramic precursors,and supramolecular melamine di-borate as an accelerator.We demonstrate that this hybrid coating can transform into a porous,fire-resistant protective layer with a highly thermostable vitreous phase upon exposure to flame/heat source.A nanosystem coating of just~100μm thickness can significantly increase the limiting oxygen index of wood(Pine)to 37.3%,dramatically reduce total heat release by 78.6%,and maintain low smoke toxicity(CIT_G=0.016).Detailed molecular force analysis,combined with a comprehensive examination of the underlying flame-retardant mechanisms,underscores the effectiveness of this coating.This work offers a strategy for creating efficient,environmentally friendly coatings with fire safety applications across various industries.展开更多
Machine picking in cotton is an emerging practice in India,to solve the problems of labour shortages and production costs increasing.Cotton production has been declining in recent years;however,the high density planti...Machine picking in cotton is an emerging practice in India,to solve the problems of labour shortages and production costs increasing.Cotton production has been declining in recent years;however,the high density planting system(HDPS)offers a viable method to enhance productivity by increasing plant populations per unit area,optimizing resource utilization,and facilitating machine picking.Cotton is an indeterminate plant that produce excessive vegeta-tive growth in favorable soil fertility and moisture conditions,which posing challenges for efficient machine picking.To address this issue,the application of plant growth retardants(PGRs)is essential for controlling canopy architecture.PGRs reduce internode elongation,promote regulated branching,and increase plant compactness,making cotton plants better suited for machine picking.PGRs application also optimizes photosynthates distribution between veg-etative and reproductive growth,resulting in higher yields and improved fibre quality.The integration of HDPS and PGRs applications results in an optimal plant architecture for improving machine picking efficiency.However,the success of this integration is determined by some factors,including cotton variety,environmental conditions,and geographical variations.These approaches not only address yield stagnation and labour shortages but also help to establish more effective and sustainable cotton farming practices,resulting in higher cotton productivity.展开更多
基金financially supported by the National Natural Science Foundation of China(52104197)Hongkong Scholar Program(XJ2022022)+5 种基金National Science Foundation for Post-doctoral Scientists of China(2021M691549,2021M703082)National Natural Science Foundation of China(52272396,52306090)Jiangsu Provincial Double-Innovation Doctor Program(JSSCBS20210402)Natural Science Foundation of the Jiangsu Higher Education Institutions(21KJB620001)The Open Fund of the State Key Laboratory of Fire Science(SKLFS)Program(HZ2022-KF04)Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJCX22-0457)。
文摘The unparalleled energy density has granted lithium-sulfur batteries(LSBs)with attractive usages.Unfortunately,LSBs still face some unsurpassed challenges in industrialization,with polysulfides shuttling,dendrite growth and thermal hazard as the major problems triggering the cycling instability and low safety.With the merit of convenience,the method of designing functional separator has been adapted.Concretely,the carbon aerogel confined with CoS_(2)(CoS_(2)-NCA)is constructed and coated on Celgard separator surface,acquiring CoS_(2)-NCA modified separator(CoS_(2)-NCA@C),which holds the promoted electrolyte affinity and flame retardance.As revealed,CoS_(2)-NCA@C cell gives a high discharge capacity 1536.9 mAh/g at 1st cycle,much higher than that of Celgard cell(987.1 mAh/g).Moreover,the thermal runaway triggering time is dramatically prolonged by 777.4 min,corroborating the promoted thermal safety of cell.Noticeably,the higher coulombic efficiency stability and lower overpotential jointly confirm the efficacy of CoS_(2)-NCA@C in suppressing the lithium dendrite growth.Overall,this work can provide useful inspirations for designing functional separator,coping with the vexing issues of LSBs.
文摘The retarding effect of protein retarder on phosphorus building gypsum(PBG)and desulfurization building gypsum(DBG)was investigated,and the results show that protein retarder for DBG can effectively prolong the setting time and displays a better retarding effect,but for PBG shows a poor retarding effect.Furthermore,the deterioration reason of the retarding effect of protein retarder on PBG was investigated by measuring the pH value and the retarder concentration of the liquid phase from vacuum filtration of PBG slurry at different hydration time,and the measure to improve the retarding effect of protein retarding on PBG was suggested.The pH value of PBG slurry(<5.0)is lower than that of DBG slurry(7.8-8.5).After hydration for 5 min,the concentration of retarder in liquid phase of DBG slurry gradually decreases,but in liquid phase of PBG slurry continually increases,which results in the worse retarding effect of protein retarder on PBG.The liquid phase pH value of PBG slurry can be adjusted higher by sodium silicate,which is beneficial to improvement in the retarding effect of the retarder.By adding 1.0%of sodium silicate,the initial setting time of PBG was efficiently prolonged from 17 to 210 min,but little effect on the absolute dry flexural strength was observed.
文摘Based on a large number of orthogonal tests and theoretical analyses, the retarding mortar which meets the requirements of retard-bonded prestressed concrete was prepared. Initial setting time of the retarding mortar may vary from several hours to 15 d at 5 ℃-35 ℃ due to quantities and average curing temperature. And its 28 d compressive strength is above 35 MPa. Thus the influence of quantities on setting time and 28 d compressive strength, and the relationship between setting time and average curing temperature were investigated. The optimum quantities were obtained by studying the interaction of admixtures, and the retarding mechanism was discussed. Based on 52 retard-bonded prestressed strands by manual work from 24 retard-bonded prestressed concrete T-beams, static friction drag, change factor κ and friction factor μ were obtained from the test when retard-bonded prestressed strands were tensioned. Application of the retarding mortar will be vast in practical concrete projects.
基金supported by the National Natural Science Foundation of China (Grant No 50479017)the Program for Changjiang Scholars and Innovative Research Teams in Universities (Grant No IRT071)
文摘A combination of the rainfall-runoff module of the Xin’anjiang model, the Muskingum routing method, the water stage simulating hydrologic method, the diffusion wave nonlinear water stage method, and the real-time error correction method is applied to the real-time flood forecasting and regulation of the Huai River with flood diversion and retarding areas. The Xin’anjiang model is used to forecast the flood discharge hydrograph of the upstream and tributary. The flood routing of the main channel and flood diversion areas is based on the Muskingum method. The water stage of the downstream boundary condition is calculated with the water stage simulating hydrologic method and the water stages of each cross section are calculated from downstream to upstream with the diffusion wave nonlinear water stage method. The input flood discharge hydrograph from the main channel to the flood diversion area is estimated with the fixed split ratio of the main channel discharge. The flood flow inside the flood retarding area is calculated as a reservoir with the water balance method. The faded-memory forgetting factor least square of error series is used as the real-time error correction method for forecasting discharge and water stage. As an example, the combined models were applied to flood forecasting and regulation of the upper reaches of the Huai River above Lutaizi during the 2007 flood season. The forecast achieves a high accuracy and the results show that the combined models provide a scientific way of flood forecasting and regulation for a complex watershed with flood diversion and retarding areas.
文摘In the Tibet ancient buildings, there are large amounts of combustible decorative textiles that pose great potential fire hazards. Some typical textile samples were collected from the Potala Palace. Their combustion properties were analyzed by UL 94 Vertical Burning test and Limiting Oxygen Index test. The effects of plateau climate on combustion properties, an important fact required to be considered in the flame retarding design for combustible textiles, were preliminarily compared via test data in the plain and those in the plateau. Based on the foregoing analyses, some thoughts were presented on the clean and feasible flame retarding means for the decorative textiles due to their special applications in Tibet, in ancient buildings and in plateau climate. The fire resistance, weather resistance, UV resistance, endurance, ornamentation and religious performances for these textiles must be taken into considerations comprehensively in the designs.
文摘The synthesis of reaction flame retarding unsaturated polyester resin and the flame retarding mechanism are investigated.By taking the synthesis flame retarding unsaturated polyester resin as a base material,glass fibers as reinforced material,under the condition of adding graphite or carbon black respectively,the composites were manufactured.The flame retarding and antistatic properties are also studied.In the experiment,bromide-bearing flame retarding resin decomposed under a high temperature.Compound HBr was set out and retarded or stopped the flame.High concentration of HBr gas wall was formed between gas and solid phrases,which decreased flame.The results show that antistatic property of carbon black is higher than that of graphite.Adding a threshed value of 1% carbon black into composite,the antistatic property is at its highest value.
文摘The combustion mechanisms of PP / Viscose blend fabrics are briefly discussed, and the factors affecting flame retarding(FR) effect are analyzed. Apart from this, the choice of processes of FR finish is also discussed in this paper. Other factors such as coating add-on, curing temperature and time are studied too. The results show that the factors above all have different extent of influence upon FR effect.
基金funding from the Euratom research and training programme 2014–2018 under grant agreement No.633053supported by the National Magnetic Confinement Fusion Science Program of China under Contracts No.20113GB106003
文摘A multi-channel retarding field analyzer（MC-RFA） including two RFA modules and two Langmuir probes to measure the ion and electron temperature profiles within the scrape-off layer was developed for investigations of the interplay between magnetic topology and plasma transport at the plasma boundary.The MC-RFA probe for the stellarator W7-X and first measurements at the tokamak EAST was designed.The probe head allows simultaneous multichannel ion temperature as well as for electron temperature measurements.The usability for radial correlation measurements of the measured ion currents is also given.
基金supported by National Natural Science Foundation of China(No.11305070)the Ministry of Science and Technology(No.2013GB106001)the Open Foundation of the Key Laboratory of Geospace Environment,the CSA/SAFEA International Partnership Program for Creative Research Teams
文摘Radial profiles of the ion temperature,Ti,have been measured by a double-sided retarding field analyzer（RFA） in the scrape-off layer（SOL） of the J-TEXT tokamak（R = 105 cm,r = 25-29 cm,Bt = 1.8-2.0 T,Ip = 120-180 kA,ne =（2-2.5） × 10^19 m^-3）.Strongly declining Ti profiles in the SOL have been found.The different e-folding lengths,At,of the Ti profiles in two experimental configurations with different magnetic connection lengths,Lc,reveal that a longer Lc results in weaker parallel energy transport and longer At.In similarity with the particle transport across the SOL,At is approximately proportional to the square root of Lc.Additionally,the poloidal asymmetry has been identified with enhanced ion energy transport across the SOL on the low-field side.
基金Funded by the National Natural Science Foundation of China(51409202)the Fundamental Research Funds for the Central Universities(2013-IV-36)the Jiangxi Provincial Project of Science and Technology(20132GGB70107)
文摘The primary objective of this research was to determine optimum dosage of mixing concrete containing plasticizers and fly ash, consistent with desirable structural grade concrete properties. Factorial tests were also conducted to investigate the four main factors： water-cementing materials ratio, water content, content of superplasticizers （SP） and fly ash content. It was found that the requirement for setting time played the dominant role in shrinkage and anti-cracking, and fly ash played a critical role in workability and reducing heat of hydration but showed insignificant effects on slump, early strength and initial setting time of concrete.
基金Key Science and Technology Development Fund Project of Hubei Province.China(No.941PO106).
文摘N-2000 is an admixture for concrete,with a low slump loss,high range water-reducing ratio and long-time retarding.The N-2000 is made up of naphthalene-sulfonic-maldehyde polycondensation(NSMP)and ATMP.Its characteristic results from the synergistic effects of NSMP and ATMP.The results show that when 0.7%-1.2%of N-2000 is added to concrete(by mass of cement),the water reducing ratio is up to 20%-30%,and the slump of fresh concrete can be retained for 2 hours without significant loss.N-2000 can not only improve the workability of fresh concrete but also increase the strength of the hardened concrete,especially early strength.It is also proved to have a good compatibility with various cements.
基金supported by National Natural Science Foundation of China(No.10805004)the Fundamental Research Funds for the Central Universities of China(No.YWF-13-D2-HT-12)
文摘An anomalous phenomenon was observed in the retarding potential analyzer （RPA） measurements of the energy of the ion beam from an 8 cm argon ion source. The current-voltage （Ⅰ- Ⅴ） curve, which should theoretically descend, went up as the ion retarding potential was increased. Various explanations, such as the Townsend discharge theory and secondary electron emission etc. were proposed but denied by the theory application condition or the experiment results. An angle of about -10° was found between the axes of the ion beam and the RPA according to the contours of the ion beam density and direction. The particle simulation and experiment of the sum of the collector and wall current were conducted at different incident ion angles. The trends of the Ⅰ- Ⅴ curve in simulation results conformed with the experimental results in most cases. The ion trajectories were simulated at different retarding potentials with an incident angle of -10°. According ：to these results, the reason for the anomalous phenomenon is that when there is a specific angle between the axes of the ion beam and the RPA, more ions are repelled from the vicinity of the ion retarding grid to avoid striking on the grid as the ion retarding potential increases. These redundant ions reach the plate and thus lead to the formation of an ascending Ⅰ- Ⅴ curve.
基金funding support of the Key Laboratory of Flame Retardancy Finishing of Textile Materials,CNTAC(Q811580421)Australian Research Council(Nos.DP190102992 and FT190100188)the National Natural Science Foundation of China(Nos.51803200 and 52003104)。
文摘Flame-retardant composites with high electromagnetic interference(EMI)shielding performance are desirable for electronic device packaging.Despite great potential of MXene for high EMI,it still remains a great challenge to develop high-performance flame-retardant polymer/MXene composites with excellent EMI shielding effectiveness because of the poor oxidative stability of MXene.Herein,phosphorylated MXene/polypropylene(PP)composites are prepared by coating phosphorylated MXene on PP fabric followed by spraying polyethylenimine(PEI)and hot-pressing.The phosphorylated MXene proves to be more durable against oxidation than pure MXene due to the protection effect of polyphosphates.Upon hot-pressing,melted PP fibers are fused together at their contact points and thus as-prepared composites are bi-continuous with two interpenetrating phases.The composites show significantly improved thermal stability and flame retardancy relative to pure PP,with a low total heat release(THR)of 3.7 kJ/g and a heat release rate(HRR)of 50.0 W/g,which are reduced by 78%and 87%,respectively.In addition,the composites exhibit a high electrical conductivity of~36,700 S/m and an EMI shielding performance of~90 d B over the whole frequency range of 8–12 GHz with a thickness of~400μm.The as-developed PP/MXene composites hold great promise for reliable protection of next-generation electronic devices working in complex environments.
基金the National Natural Science Foundation of China(No.21801097)the Australian Re-search Council(Nos.DP190102992 and FT190100188).
文摘Renewable and biodegradable polylactide (PLA) has excellent mechanical strength but is highly flammable which restricts its practical applications. Many phosphorus/nitrogen (P/N)-based flame retardants are ef- fective in PLA, but their high addition loading usually decreases the mechanical strength of the PLA bulk. For polyphosphoramides, despite high fire-retardant efficiency, their chemical synthesis often generates chemical wastes as byproducts. Herein, we report an atom-economic and highly efficient oligomeric P/N fire retardant (APN) prepared using a mild Michael addition polymerization with no byproducts. Using only 3 wt% APN, the resulting PLA exhibits desired fire retardancy including a UL-94 V-0 rating and a limiting oxygen index of 37.6%. Furthermore, the toughness of the fire-retardant PLA increases by 85% compared to pure PLA, with both tensile strength and thermal stability preserved. This work offers an atom-economic strategy for synthesizing highly efficient P/N fire retardants for use in the creation of fire-resistant PLA with robust mechanical properties.
文摘An organophosphorus-based diamine has been synthesized and used as a curing and flame retarding bifunctional agent for epoxy resins.This phosphorodiamidate functions not only as a crosslinking materials in the Epon 828 epoxy resin curing process but also as a fire retarding compound to produce thin films or composites upon curing.This phosphorus-containing reactive amine was synthesized via condensation of phenyphosphonic dichloride with ethylenediamine in the presence of sodium methoxide.The product was then purified and later characterized by NMR and FTIR spectroscopy as well as MALDI-TOF mass spectrometry.Kinetics studies of the curing reaction of the phosphorodiamidate were carried out in comparison with the non-phosphorus containing ethylenediamine reference crosslinking agent.Thermal stability of the cured epoxy ware investigated by thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC).Moreover,flame retardant properties of the obtained materials was investigated by limiting oxygen index(LOI)measurements as well as the UL-40 method.The obtained results show that epoxy resin cured with phosphorodiamidate possesses higher thermostability compared to the epoxy cured with the regular ethylenediamine counterpart.This is evident by higher amount of char formed upon burning.More importantly,the LOI value of 27 was observed in the phosphorodiamidate-cured epoxy resin compared with LOI of 20 of the epoxy resin cured with ethylenediamine where no phosphorus was present.The UL-94 highest rating of V-0 materials was obtained with only about 2-3 wt%of the phosphorus element.The chemistry,curing kinetics,and thermal properties of these new epoxy formulations are discussed.
基金financial support from the National Natural Science Foundation of China (grant no.51772199)the Natural Science Foundation of Jiangsu Province (Grant no.BK20170329)+2 种基金the Collaborative Innovation Center of Suzhou Nano Science & Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutionsthe 111 Project。
文摘Polymeric organic battery materials are promising alternatives to the transition-metal-based ones owing to their enriched chemistries. However, the flammability of organic compounds brings in serious concern on battery safety. In addition to use flame-retarding electrolyte/electrolyte additives or battery separators,flame retardancy can readily be achieved through the integration of flame-retarding unit into the polymer backbone, imparting the flame retardancy permanently. The as-designed polymer based on phenothiazine shows significantly shortened self-extinguished time without deteriorating its intrinsic thermodynamic and electrochemical properties. Moreover, two electron per phenothiazine molecule is realized for the first time in a highly reversible manner with discharge voltages of 3.52 V and 4.16 V versus Li+/Li and an average capacity of ca. 120 mAh g-1 at a current rate of 2 C. The origin of the reversibility is investigated through density functional theory(DFT) calculations. These findings address the importance of molecular design for safer and more stable organic materials for batteries.
文摘High-performance MXene-based polymer nanocomposites are well-suited for various industrial applications owing to their excellent mechanical,thermal,and other properties.However,the fabrication of flame-retardant polymer/MXene nanocom-posites remains challenging owing to the limited flame-retardant properties of MXene itself.This study prepared a novel MXene@Ag@PA hybrid material via radiation modification and complexation reaction.This material was used to further enhance the key properties of ethylene-vinyl acetate(EVA),such as its mechanical properties,thermal conductivity,flame retardancy,and electromagnetic shielding.The addition of two parts of this hybrid material increased the thermal conduc-tivity of EVA by 44.2%and reduced its peak exothermic rate during combustion by 30.1%compared with pure EVA.The material also significantly reduced smoke production and increased the residue content.In the X-band,the electromagnetic shielding effectiveness of the EVA composites reached 20 dB.Moreover,the MXene@Ag@PA hybrid material could be used to further enhance the mechanical properties of EVA composites under electron-beam irradiation.Thus,this study contributes to the development of MXene-based EVA advanced materials that are fire-safe,have high strength,and exhibit good electromagnetic shielding performance for various applications.
基金supported by the China Scholarship Council(Grant No.202306690024)the Ministerio de Ciencia e Innovación and Fondos FEDER(Grant Nos.PID2021-562126509OB-C21 and PDC2022-133332-C21)+1 种基金the Generalitat de Catalunya(Grant No.2021SGR00138)the Beatriu de Pinós Fellowship(Grant No.2021-BP-00206).
文摘Depolarizing behavior is commonly observed in most natural samples.For this reason,optical tools measuring the differences in depolarization response among spatially separated structures are highly useful in a wide range of imaging applications for enhanced visualization of structures,target identification,etc.One commonly used tool for depolarizing discrimination is the so-called depolarizing spaces.In this article,we exploit the combined use of two depolarizing spaces,the indices of polarization purity(IPP)and polarizance–reflection–transformation(PRT)spaces,to improve the capability of optical systems to identify polarization–anisotropy depolarizers.The potential of these spaces to discriminate among different depolarizers is first studied from a series of simulations by incoherently adding diattenuations or retarders,with some control parameters emulating samples in nature.The simulated results demonstrate that the proposed methods are capable of increasing differences among depolarizers beyond other well-known techniques.Experimentally,validation is provided by conducting diverse phantom experiments of easy interpretation and mimicking the stated simulations.As a useful application of our approach,we developed a model able to retrieve intrinsic microscopic information of samples from macroscopic polarimetric measurements.The proposed methods enable non-invasive,straightforward,macroscopic characterization of depolarizing samples,and may be of interest for enhanced visualization of samples in multiple imaging scenarios.
基金the financial support from the National Natural Science Foundation of China(524B2168,U22A20149,52173081,and 52273275)。
文摘In recent decades,annual urban fire incidents,including those involving ancient wooden buildings burned,transportation,and solar panels,have increased,leading to significant loss of human life and property.Addressing this issue without altering the surface morphology or interfering with optical behavior of flammable materials poses a substantial challenge.Herein,we present a transparent,low thickness,ceramifiable nanosystem coating composed of a highly adhesive base(poly(SSS1-co-HEMA1)),nanoscale layered double hydroxide sheets as ceramic precursors,and supramolecular melamine di-borate as an accelerator.We demonstrate that this hybrid coating can transform into a porous,fire-resistant protective layer with a highly thermostable vitreous phase upon exposure to flame/heat source.A nanosystem coating of just~100μm thickness can significantly increase the limiting oxygen index of wood(Pine)to 37.3%,dramatically reduce total heat release by 78.6%,and maintain low smoke toxicity(CIT_G=0.016).Detailed molecular force analysis,combined with a comprehensive examination of the underlying flame-retardant mechanisms,underscores the effectiveness of this coating.This work offers a strategy for creating efficient,environmentally friendly coatings with fire safety applications across various industries.
文摘Machine picking in cotton is an emerging practice in India,to solve the problems of labour shortages and production costs increasing.Cotton production has been declining in recent years;however,the high density planting system(HDPS)offers a viable method to enhance productivity by increasing plant populations per unit area,optimizing resource utilization,and facilitating machine picking.Cotton is an indeterminate plant that produce excessive vegeta-tive growth in favorable soil fertility and moisture conditions,which posing challenges for efficient machine picking.To address this issue,the application of plant growth retardants(PGRs)is essential for controlling canopy architecture.PGRs reduce internode elongation,promote regulated branching,and increase plant compactness,making cotton plants better suited for machine picking.PGRs application also optimizes photosynthates distribution between veg-etative and reproductive growth,resulting in higher yields and improved fibre quality.The integration of HDPS and PGRs applications results in an optimal plant architecture for improving machine picking efficiency.However,the success of this integration is determined by some factors,including cotton variety,environmental conditions,and geographical variations.These approaches not only address yield stagnation and labour shortages but also help to establish more effective and sustainable cotton farming practices,resulting in higher cotton productivity.
