Nutritional value of a partially defatted and a highly defatted black soldier fly larvae (Hermetia illucens L.) meal for broiler chickens: apparent nutrient digestibility,apparent metabolizable energy and apparent ileal amino acid digestibility

Background: The study aimed to determine the apparent total tract digestibility coefficients(ATTDC) of nutrients, the apparent metabolizable energy(AME and AMEn) and the amino acid(AA) apparent ileal digestibility coefficients(AIDC)of a partially defatted(BSFp) and a highly defatted(BSFh) black soldier fly larvae meal. The experimental diets were: a basal diet and two diets prepared by substituting 250 g/kg(w/w) of the basal diet with BSFp or BSFh, respectively.Results: Significant differences were found between BSFp and BSFh meals for ATTDC of the nutrients: BSFp resulted more digestible than BSFh, except for ATTDC of CP which did not differed between meals, while a statistical trend was observed for ATTDC of DM and EE. The AME and AMEn values were significantly(P < 0.05) different between the two BSF meals, with higher levels for BSFp(16.25 and 14.87 MJ/kg DM, respectively). The AIDC of the AA in BSFp ranged from 0.44 to 0.92, while in BSFh they ranged from 0.45 to 0.99. No significant differences were observed for the AA digestibility(0.77 and 0.80 for BSFp and BSFh, respectively), except for glutamic acid, proline and serine that were more digestible in the BSFh meal(P < 0.05).Conclusions: Defatted BSF meals can be considered as an excellent source of AME and digestible AA for broilers with a better efficient nutrient digestion. These considerations suggested the effective utilization of defatted BSF larvae meal in poultry feed formulation.

Recent advances in graphene-based phase change composites for thermal energy storage and management

Energy storage and conservation are receiving increased attention due to rising global energy demands.Therefore,the development of energy storage materials is crucial.Thermal energy storage(TES)systems based on phase change materials(PCMs)have increased in prominence over the past two decades,not only because of their outstanding heat storage capacities but also their superior thermal energy regulation capability.However,issues such as leakage and low thermal conductivity limit their applicability in a variety of settings.Carbon-based materials such as graphene and its derivatives can be utilized to surmount these obstacles.This study examines the recent advancements in graphene-based phase change composites(PCCs),where graphene-based nanostructures such as graphene,graphene oxide(GO),functionalized graphene/GO,and graphene aerogel(GA)are incorporated into PCMs to substantially enhance their shape stability and thermal conductivity that could be translated to better storage capacity,durability,and temperature response,thus boosting their attractiveness for TES systems.In addition,the applications of these graphene-based PCCs in various TES disciplines,such as energy conservation in buildings,solar utilization,and battery thermal management,are discussed and summarized.

The effect of the ratio of standardized ileal digestible lysine to metabolizable energy on growth performance,blood metabolites and hormones of lactating sows

A total of 335 lactating sows （Landrace x Large White） were used in two experiments to determine the optimum ratio of standardized ileal digestible lysine （SID-Lys） to metabolizable energy （ME） for mixed parity sows during lactation. In Exp. 1, 185 sows （weighing an average of 256.2 ± 6.5 kg and having an average parity of 3.4 ± 0.3） were allocated to one of six experimental diets in a completely randomized block design within parity groups （1, 2, and 3＋）. The experimental diets were formulated to contain 3.06, 3.16, 3.20, 3.25, 3.30 or 3.40 Mcal/kg of ME and each diet was fed to the sows throughout a 28 day lactation. All diets provided a similar SID-lysine level （0.86%）. As a result, the diets provided a SID-Lys：ME ratio of 2.81, 2.72, 2.69, 2.65, 2.61 or 2.53 g/Mcal ME. Sow feed intake was significantly （P 〈 0.01） affected by the energy content of the diet as well as by sow parity. Using regression analysis, feed intake was shown to be maximized at 3.25, 3.21, 3.21 and 3.21 Mcal/kg of ME for parity 1, 2, 3＋ sows and the entire cohort of sows respectively （quadratic; P 〈 0.01）. In addition, the result of feed intake can be expressed as 2.65, 2.69, 2.69 and 2.68 g/Mcal based on analysis of SID-Lys：ME ratio. Litter weight gain was affected by dietary treatment for parity 3＋ sows and the entire cohort （P 〈 0.01）. Based on regression analysis, litter weight gain was maximized at 3.25 and 3.24 Mcal/kg of ME for parity 3＋ （quadratic; P 〈 0.01） and the entire cohort （quadratic; P 〈 0.01）. Similarly, the result of litter weight gain could be expressed as 2.65 and 2.66 g/Mcal of SID- Lys：ME ratio. Therefore, 3.25 Mcal/kg of ME was selected for Exp. 2 in which 150 sows （weighing 254.6 ± 7.3 kg and having an average parity of 3.4 ± 0.4） were allocated to one of five treatments in a completely randomized block design within parity （1, 2, and 3＋）. The experimental diets were formulated to contain 2.1, 2.4, 2.7, 3.0 or 3.3 g/Mcal of SID-Lys：ME ratio with all diets providing 3.25 Mcal/kg of ME. The diets were fed to the sows throughout a 28 day lactation. Sow body weight loss was affected by dietary treatment （parity 3＋ sows, P = 0.02; entire cohort, P 〈 0.01） and by sow parity （P 〈 0.01）. Litter weight at weaning and litter weight gain were affected by dietary treatment for parity 1, 2, 3＋ sows and the entire cohort （P 〈 0.01） as well as by sow parity （P 〈 0.01）. Plasma urea nitrogen （P 〈 0.01）, creatinine （P 〈 0.01） and non-esterifide fatty acids （P = 0.04） were decreased as the SID-Lys：ME ratio of the diet increased. Insulin-like growth factor-1 （P = 0.02）, estradiol （P 〈 0.01） and luteinizing hormone （P = 0.02） were increased as the SID-Lys：ME ratio in diet increased. Based on a broken-line model, the estimated SID-Lys： ME ratio to maximize litter weight gain was estimated to be 3.05 g/Mcal.

Metal-organic framework-based single-atom electro-/ photocatalysts: Synthesis, energy applications, and opportunities

Single-atom catalysts(SACs)have gained substantial attention because of their exceptional catalytic properties.However,the high surface energy limits their synthesis,thus creating significant challenges for further development.In the last few years,metal–organic frameworks(MOFs)have received significant consideration as ideal candidates for synthesizing SACs due to their tailorable chemistry,tunable morphologies,high porosity,and chemical/thermal stability.From this perspective,this review thoroughly summarizes the previously reported methods and possible future approaches for constructing MOF-based(MOF-derived-supported and MOF-supported)SACs.Then,MOF-based SAC's identification techniques are briefly assessed to understand their coordination environments,local electronic structures,spatial distributions,and catalytic/electrochemical reaction mechanisms.This review systematically highlights several photocatalytic and electrocatalytic applications of MOF-based SACs for energy conversion and storage,including hydrogen evolution reactions,oxygen evolution reactions,O_(2)/CO_(2)/N_(2) reduction reactions,fuel cells,and rechargeable batteries.Some light is also shed on the future development of this highly exciting field by highlighting the advantages and limitations of MOF-based SACs.

Oxygen functionalization-assisted anionic exchange toward unique construction of flower-like transition metal chalcogenide embedded carbon fabric for ultra-long life flexible energy storage and conversion

The metal-organic framework(MOF)derived Ni–Co–C–N composite alloys(NiCCZ)were“embedded”inside the carbon cloth(CC)strands as opposed to the popular idea of growing them upward to realize ultrastable energy storage and conversion application.The NiCCZ was then oxygen functionalized,facilitating the next step of stoichiometric sulfur anion diffusion during hydrothermal sulfurization,generating a flower-like metal hydroxysulfide structure(NiCCZOS)with strong partial implantation inside CC.Thus obtained NiCCZOS shows an excellent capacity when tested as a supercapacitor electrode in a three-electrode configuration.Moreover,when paired with the biomass-derived nitrogen-rich activated carbon,the asymmetric supercapacitor device shows almost 100%capacity retention even after 45,000 charge–discharge cycles with remarkable energy density(59.4 Wh kg^(-1)/263.8μWh cm^(–2))owing to a uniquely designed cathode.Furthermore,the same electrode performed as an excellent bifunctional water-splitting electrocatalyst with an overpotential of 271 mV for oxygen evolution reaction(OER)and 168.4 mV for hydrogen evolution reaction(HER)at 10 mA cm−2 current density along with 30 h of unhinged chronopotentiometric stability performance for both HER and OER.Hence,a unique metal chalcogenide composite electrode/substrate configuration has been proposed as a highly stable electrode material for flexible energy storage and conversion applications.

Predicting corn digestible and metabolizable energy content from its chemical composition in growing pigs

Background： The nutrient composition of corn is variable. To prevent unforeseen reductions in growth performance, grading and analytical methods are used to minimize nutrient variability between calculated and analyzed values. This experiment was carried out to define the sources of variation in the energy content of corn and to develop a practical method to accurately estimate the digestible energy （DE） and metabolisable energy （ME） content of individual corn samples for growing pigs. Twenty samples were taken from each of five provinces in China （Jilin, Hebei, Shandong, Liaoning, and Henan） to obtain a range of quality. Results： The DE and ME contents of the 100 corn samples were measured in 3.5.3 ±1.92 kg growing pigs （six pigs per corn sample）. Sixty corn samples were used to build the prediction model; the remaining forty samples were used to test the suitability of these models. The chemical composition of each corn sample was determined, and the results were used to establish prediction equations for DE or ME content from chemical characteristics. The mean DE and ME content of the 100 samples were 4,053 and 3,923 kcal/kg （dry matter basis）, respectively. The physical characteristics were determined, as well, and the results indicated that the bulk weight and 1,000-kernel weight were not associated with energy content. The DE and ME values could be accurately predicted from chemical characteristics. The best fit equations were as follows： DE, kcal/kg of DM = 1062.68 ＋ （49.72 ×EE） ＋ （0.54 × GE） ＋ （9.1 ] x starch）, with R^2 = 0.62, residual standard deviation （RSD） = 48 kcal/kg, and P 〈 0.01; ME, kcal/kg of dry matter basis （DM） = 671.54 ＋ （0.89 ×DE） - （5.57 × NDF） - （191.39 ×ash）, with R^2 = 0.87, RSD = 18 kcal/kg, and P〈 0.01. Conclusion： This experiment confirms the large variation in the energy content of corn, describes the factors that influence this variation, and presents equations based on chemical measurements that may be used to predict the DE and ME content of individual corn samples.

Co-Harvest Phase-Change Enthalpy and Isomerization Energy for High-Energy Heat Output by Controlling Crystallization of Alkyl-Grafted Azobenzene Molecules

Photoisomerization-induced phase change are important for co-harvesting the latent heat and isomerization energy of azobenzene molecules.Chemically optimizing heat output and energy delivery at alternating temperatures are challenging because of the differences in crystallizability and isomerization.This article reports two series of asymmetrically alkyl-grafted azobenzene(Azo-g),with and without a methyl group,that have an optically triggered phase change.Three exothermic modes were designed to utilize crystallization enthalpy(△H_(c))and photothermal(isomerization)energy(△H_(p))at different temperatures determined by the crystallization.Azo-g has high heat output(275-303 J g^(-1))by synchronously releasing△H_(c)and△H_(p)over a wide temperature range(-79℃to 25℃).We fabricated a new distributed energy utilization and delivery system to realize a temperature increase of 6.6℃at a temperature of-8℃.The findings offer insight into selective utilization of latent heat and isomerization energy by molecular optimization of crystallization and isomerization processes.

Effects of the standardized ileal digestible lysine to metabolizable energy ratio on performance and carcass characteristics of growing-finishing pigs

A total of 2,121 growing-finishing pigs （Duroc × Landrace ×Large White） were utilized in six experiments conducted to determine the effects of different ratios of standardized ileal digestible lysine （SID-Lys） to metabolizable energy （ME） on the performance and carcass characteristics of growing-finishing pigs. Exps. 1 （30 to 50 kg）, 2 （52 to 70 kg） and 3 （81 to 104 kg） were conducted to find an optimum ME level and then this level was used in Exps. 4 （29 to 47 kg）, 5 （54 to 76 kg） and 6 （84 to 109 kg） to test the response of pigs to different ratios of SID-Lys：ME. In Exps.1 to 3, four treatments were used consisting of diets with a formulated ME content of 3.1, 3.2, 3.3 or 3.4 in Exps. I and 2 while Exp. 3 used 3.05, 3.1 S, 3.25 or 3.35 Mcal/kg. A constant SID-Lys：ME ratio of 2.6, 2.3 or 2.0 g/Mcal was used in Exps. 1, 2 and 3, respectively. Weight gain was significantly increased with increasing energy level in Exp.1 while weight gain was unaltered in Exps. 2 and 3. For all three experiments, feed intake was decreased （P 〈 0.05） and feed efficiency was improved （P 〈 0.05） with increasing energy level. Tenth rib back fat thickness linearly increased （P 〈 0.05） with increasing energy level, in Exps. 4 to 6, five treatments were used consisting of diets with a SID-Lys：ME ratio of 2.4, 2.6, 2.8, 3.0 or 3.2 in Exp. 1, 2.1, 2.3, 2.5, 2.7, 2.9 or 3.2 in Exp. 2 and 1.8, 2.0, 2.2, 2.4, or 2.6 in Exp. 3. A constant ME level 3.2, 3.2 and 3.05 Mcal/kg was used in Exps. 1, 2 and 3, respectively （selected based on the results of weight gain）. For all three experiments, weight gain increased （P 〈 0.05） and feed efficiency improved linearly （P 〈 0.05） as the SID-Lys：ME ratio increased. Tenth rib back fat thickness linearly decreased （P 〈 0.0,5） as the SID-Lys：ME ratio increased. Based on a straight broken-line model, the estimated SID-Lys：ME ratio to maximize weight gain was 3.0, 2.43 and 2.2 for 29 to 47, 54 to76 and 84 to 109 kg of pigs, respectively.

The correlationship between the metabolizable energy content,chemical composition and color score in different sources of corn DDGS

Background： This study was conducted to evaluate the apparent metabolizable energy （AME） and true metabolizable energy （TME） contents in 30 sources of corn distillers dried grains with solubles （DDGS） in adult roosters, and establish the prediction equations to estimate the AME and TME value based on its chemical composition and color score. Methods： Twenty-eight sources of corn DDGS made from several processing plants in 11 provinces of China and others imported from the United States. DDGS were analyzed for their metabolizable energy （ME） contents, measured for color score and chemical composition （crude protein, crude fat, ash, neutral detergent fiber, acid detergent fiber）, to predict the equation of ME in DDGS. A precision-fed rooster assay was used, each DDGS sample was tube fed （50 g） to adult roosters. The experiment was conducted as a randomized incomplete block design with 3 periods. Ninety-five adult roosters were used in each period, with 90 being fed the DDGS samples and 5 being fasted to estimate basal endogenous energy losses. Results： Results showed that the AME ranged from 5.93 to 12.19 MJ/kg, TME ranged from 7.28 to 13.54 MJ/kg. Correlations were found between ME and ash content （-0.64, P 〈 0.0]） and between ME and yellowness score （0.39, P 〈 0.05） of the DDGS samples. Furthermore, the best-fit regression equation for AME content of DDGS based on chemical composition and color score was AME = 6.57111 ＋ 0.5]475 GE - 0.10003 NDF ＋ 0.1 3380 ADF ＋ 0.07057 fat - 0.57029 ash - 0.02437 L （R^2 = 0.70）. The best-fit regression equation for TME content of DDGS was TME = 7.92283 ＋ 0.51475 GE - 0.10003 NDF ＋ 0.13380 ADF ＋ 0.07057 fat - 0.57029 ash - 0.02437 L （R2 = 0.70）. Conclusions： This experiment suggested that measuring the chemical composition and color score of a corn DDGS sample may provide a quality parameter for identifying corn DDGS sources energy digestibility and metabolizable energy content.

Dynamics and vibration reduction performance of asymmetric tristable nonlinear energy sink

With its complex nonlinear dynamic behavior,the tristable system has shown excellent performance in areas such as energy harvesting and vibration suppression,and has attracted a lot of attention.In this paper,an asymmetric tristable design is proposed to improve the vibration suppression efficiency of nonlinear energy sinks(NESs)for the first time.The proposed asymmetric tristable NES(ATNES)is composed of a pair of oblique springs and a vertical spring.Then,the three stable states,symmetric and asymmetric,can be achieved by the adjustment of the distance and stiffness asymmetry of the oblique springs.The governing equations of a linear oscillator(LO)coupled with the ATNES are derived.The approximate analytical solution to the coupled system is obtained by the harmonic balance method(HBM)and verified numerically.The vibration suppression efficiency of three types of ATNES is compared.The results show that the asymmetric design can improve the efficiency of vibration reduction through comparing the chaotic motion of the NES oscillator between asymmetric steady states.In addition,compared with the symmetrical tristable NES(TNES),the ATNES can effectively control smaller structural vibrations.In other words,the ATNES can effectively solve the threshold problem of TNES failure to weak excitation.Therefore,this paper reveals the vibration reduction mechanism of the ATNES,and provides a pathway to expand the effective excitation amplitude range of the NES.

Use of near-infrared reflectance spectroscopy for the rapid determination of the digestible energy and metabolizable energy content of corn fed to growing pigs

Background： The ability of near-infrared reflectance spectroscopy（NIRS） to determine the digestible energy（DE）and metabolizable energy（ME） content of corn fed to growing pigs was tested. One hundred and seventeen corn samples, comprising different planting regions and varieties were collected from all over China in a three-year period. The samples were randomly split into a calibration set（n = 88） and a validation set（n = 29）. The actual and calculated DE and ME content of the corn samples was determined by digestion-metabolism experiments and the prediction equations of Noblet and Perez（J Anim Sci. 71：3389–98,1993）. The samples were then subjected to NIRS scanning and calibrations were performed by the modified partial least square（MPLS） regression method based on77 different spectral pre-treatments. The NIRS equations based on the actually determined and calculated DE and ME were built separately and then validated using validation samples.Results： The NIRS equations obtained from actually determined DE, the coefficient of determination for calibration（RSQcal）, cross-validation（R^2CV）, and validation（RSQv） were 0.89, 0.87 and 0.86, and these values for determined ME were 0.87, 0.86 and 0.86. For the NIRS equations built from calculated DE, the RSQcal, R^2CV, and RSQvvalues were 0.88, 0.85 and 0.84, and these values for calculated ME were 0.86, 0.84 and 0.82. Except for the equation based on calculated ME（RPD_v= 2.38, 〈 2.50）, the other three equations built from actually determined energy and calculated DE produced good prediction performance（RPD_vranging from 2.53 to 2.69, 〉 2.50） when applied to validation samples.Conclusion： These results indicate that NIRS can be used as a quantitative method for the rapid determination of the available energy in corn fed to growing pigs, and the NIRS equations based on the actually determined energy produced better predictive performance than those built from calculated energy values.

Development status and prospect of underground thermal energy storage technology

Underground Thermal Energy Storage(UTES)store unstable and non-continuous energy underground,releasing stable heat energy on demand.This effectively improve energy utilization and optimize energy allocation.As UTES technology advances,accommodating greater depth,higher temperature and multi-energy complementarity,new research challenges emerge.This paper comprehensively provides a systematic summary of the current research status of UTES.It categorized different types of UTES systems,analyzes the applicability of key technologies of UTES,and evaluate their economic and environmental benefits.Moreover,this paper identifies existing issues with UTES,such as injection blockage,wellbore scaling and corrosion,seepage and heat transfer in cracks,etc.It suggests deepening the research on blockage formation mechanism and plugging prevention technology,improving the study of anticorrosive materials and water treatment technology,and enhancing the investigation of reservoir fracture network characterization technology and seepage heat transfer.These recommendations serve as valuable references for promoting the high-quality development of UTES.

Nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in aerospace community:a comparative analysis

The aerospace community widely uses difficult-to-cut materials,such as titanium alloys,high-temperature alloys,metal/ceramic/polymer matrix composites,hard and brittle materials,and geometrically complex components,such as thin-walled structures,microchannels,and complex surfaces.Mechanical machining is the main material removal process for the vast majority of aerospace components.However,many problems exist,including severe and rapid tool wear,low machining efficiency,and poor surface integrity.Nontraditional energy-assisted mechanical machining is a hybrid process that uses nontraditional energies(vibration,laser,electricity,etc)to improve the machinability of local materials and decrease the burden of mechanical machining.This provides a feasible and promising method to improve the material removal rate and surface quality,reduce process forces,and prolong tool life.However,systematic reviews of this technology are lacking with respect to the current research status and development direction.This paper reviews the recent progress in the nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in the aerospace community.In addition,this paper focuses on the processing principles,material responses under nontraditional energy,resultant forces and temperatures,material removal mechanisms,and applications of these processes,including vibration-,laser-,electric-,magnetic-,chemical-,advanced coolant-,and hybrid nontraditional energy-assisted mechanical machining.Finally,a comprehensive summary of the principles,advantages,and limitations of each hybrid process is provided,and future perspectives on forward design,device development,and sustainability of nontraditional energy-assisted mechanical machining processes are discussed.

Hyphae-mediated bioassembly of carbon fibers derivatives for advanced battery energy storage

Ingenious design and fabrication of advanced carbon-based sulfur cathodes are extremely important to the development of high-energy lithium-sulfur batteries,which hold promise as the next-generation power source.Herein,for the first time,we report a novel versatile hyphae-mediated biological assembly technology to achieve scale production of hyphae carbon fibers(HCFs)derivatives,in which different components including carbon,metal compounds,and semiconductors can be homogeneously assembled with HCFs to form composite networks.The mechanism of biological adsorption assembly is also proposed.As a representative,reduced graphene oxides(rGOs)decorated with hollow carbon spheres(HCSs)successfully co-assemble with HCFs to form HCSs@rGOs/HCFs hosts for sulfur cathodes.In this unique architecture,not only large accommodation space for sulfur but also restrained volume expansion and fast charge transport paths are realized.Meanwhile,multiscale physical barriers plus chemisorption sites are simultaneously established to anchor soluble lithium polysulfides.Accordingly,the designed HCSs@rGOs/HCFs-S cathodes deliver a high capacity(1189 mA h g^(-1)at 0.1 C)and good high-rate capability(686 mA h g^(-1)at 5 C).Our work provides a new approach for the preparation of high-performance carbon-based electrodes for energy storage devices.

A game-theoretic approach for federated learning:A trade-off among privacy,accuracy and energy

Benefiting from the development of Federated Learning(FL)and distributed communication systems,large-scale intelligent applications become possible.Distributed devices not only provide adequate training data,but also cause privacy leakage and energy consumption.How to optimize the energy consumption in distributed communication systems,while ensuring the privacy of users and model accuracy,has become an urgent challenge.In this paper,we define the FL as a 3-layer architecture including users,agents and server.In order to find a balance among model training accuracy,privacy-preserving effect,and energy consumption,we design the training process of FL as game models.We use an extensive game tree to analyze the key elements that influence the players’decisions in the single game,and then find the incentive mechanism that meet the social norms through the repeated game.The experimental results show that the Nash equilibrium we obtained satisfies the laws of reality,and the proposed incentive mechanism can also promote users to submit high-quality data in FL.Following the multiple rounds of play,the incentive mechanism can help all players find the optimal strategies for energy,privacy,and accuracy of FL in distributed communication systems.

Plasma‐oxidized 2D MXenes subnanochannel membrane for high‐performance osmotic energy conversion

Nanofluidic channels inspired by electric eels open a new era of efficient harvesting of clean blue osmotic energy from salinity gradients.Limited by less charge and weak ion selectivity of the raw material itself,energy conversion through nanofluidic channels is still facing considerable challenges.Here,a facile and efficient strategy to enhance osmotic energy harvesting based on drastically increasing surface charge density of MXenes subnanochannels via oxygen plasma is proposed.This plasma could break Ti–C bonds in the MXenes subnanochannels and effectively facilitate the formation of more Ti–O,C═O,O–OH,and rutile with a stronger negative charge and work function,which leads the surface potential of MXenes membrane to increase from 205 to 430 mV.This significant rise of surface charge endows the MXenes membrane with high cation selectivity,which could make the output power density of the MXenes membrane increase by 248.2%,reaching a high value of 5.92Wm^(−2) in the artificial sea‐river water system.Furthermore,with the assistance of low‐quality heat at 50℃,the osmotic power is enhanced to an ultrahigh value of 9.68Wm^(−2),which outperforms those of the state‐of‐the‐art two‐dimensional(2D)nanochannel membranes.This exciting breakthrough demonstrates the enormous potential of the facile plasma‐treated 2D membranes for osmotic energy harvesting.

Reinforcing effects of polypropylene on energy absorption and fracturing of cement-based tailings backfill under impact loading

Polypropylene(PP)fiber-reinforced cement-based tailings backfill(FRCTB)is a green compound material with superior crack resistance and has good prospects for application in underground mining.However,FRCTB exhibits susceptibility to dynamic events,such as impact ground pressure and blast vibrations.This paper investigates the energy and crack distribution behavior of FRCTB under dynamic impact,considering the height/diameter(H/D)effect.Split Hopkinson pressure bar,industrial computed tomography scan,and scanning electron microscopy(SEM)experiments were carried out on six types of FRCTB.Laboratory outcomes confirmed fiber aggregation at the bottom of specimens.When H/D was less than 0.8,the proportion of PP fibers distributed along theθangle direction of80°-90°increased.For the total energy,all samples presented similar energy absorption,reflectance,and transmittance.However,a rise in H/D may cause a rise in the energy absorption rate of FRCTB during the peak phase.A positive correlation existed between the average strain rate and absorbed energy per unit volume.The increase in H/D resulted in a decreased crack volume fraction of FRCTB.When the H/D was greater than or equal to 0.7,the maximum crack volume fraction of FRCTB was observed close to the incidence plane.Radial cracks were present only in the FRCTB with an H/D ratio of 0.5.Samples with H/D ratios of 0.5 and 0.6 showed similar distributions of weakly and heavily damaged areas.PP fibers can limit the emergence and expansion of cracks by influencing their path.SEM observations revealed considerable differences in the bonding strengths between fibers and the FRCTB.Fibers that adhered particularly well to the substrate were attracted together with the hydration products adhering to surfaces.These results show that FRCTB is promising as a sustainable and green backfill for determining the design properties of mining with backfill.

Dynamical Dark Energy in Light of Cosmic Distance Measurements.Ⅱ.A Study Using Current Observations

We extract key information on dark energy from current observations of BAO,OHD and H_(0),and find hints of dynamical behavior of dark energy.In particular,a dynamical dark energy model whose equation of state crosses-1 is favored by observations.We also find that the Universe has started accelerating at a lower redshift than expected.

Permeability and selectivity synergistically enhanced nanofluidic membrane for osmotic energy harvesting

For the porous‐membrane‐based osmotic energy generator,the potential synergistic enhancement mechanism of various key parameters is still controversial,especially because optimizing the trade‐off between permeability and selectivity is still a challenge.Here,to construct a permeability and selectivity synergistically enhanced osmotic energy generator,the twodimensional porous membranes with tunable charge density are prepared by inserting sulfonated polyether sulfone into graphene oxide.Influences of charge density and pore size on the ion transport are explored,and the ionic behaviors in the channel are calculated by numerical simulations.The mechanism of ion transport in the process is studied in depth,and the fundamental principles of energy conversion are revealed.The results demonstrate that charge density and pore size should be matched to construct the optimal ion channel.This collaborative enhancement strategy of permeability and selectivity has significantly improved the output power in osmotic energy generation;compared to the pure graphene oxide membrane,the composite membrane presents almost 20 times improvement.

Ultraviolet‑Irradiated All‑Organic Nanocomposites with Polymer Dots for High‑Temperature Capacitive Energy Storage

Polymer dielectrics capable of operating efficiently at high electric fields and elevated temperatures are urgently demanded by next-generation electronics and electrical power systems.While inorganic fillers have been extensively utilized to improved high-temperature capacitive performance of dielectric polymers,the presence of thermodynamically incompatible organic and inorganic components may lead to concern about the long-term stability and also complicate film processing.Herein,zero-dimensional polymer dots with high electron affinity are introduced into photoactive allyl-containing poly(aryl ether sulfone)to form the all-organic polymer composites for hightemperature capacitive energy storage.Upon ultraviolet irradiation,the crosslinked polymer composites with polymer dots are efficient in suppressing electrical conduction at high electric fields and elevated temperatures,which significantly reduces the high-field energy loss of the composites at 200℃.Accordingly,the ultraviolet-irradiated composite film exhibits a discharged energy density of 4.2 J cm^(−3)at 200℃.Along with outstanding cyclic stability of capacitive performance at 200℃,this work provides a promising class of dielectric materials for robust high-performance all-organic dielectric nanocomposites.