Optimization of Sound Absorption and Insulation Performances of a Dual-Cavity Resonant Micro-Perforated Plate

This study investigates a dual-cavity resonant composite sound-absorbing structure based on a micro-perforated plate.Using the COMSOL impedance tube model,the effects of various structural parameters on sound absorption and sound insulation performances are analyzed.Results show that the aperture of the micro-perforated plate has the greatest influence on the sound absorption coefficient;the smaller the aperture,the greater is this coefficient.The thickness of the resonance plate has the most significant influence on the sound insulation and resonance frequency;the greater the thickness,the wider the frequency domain in which sound insulation is obtained.In addition,the effect of filling the structural cavity with porous foam ceramics has been studied,and it has been found that the porosity and thickness of the porous material have a significant effect on the sound absorption coefficient and sound insulation,while the pore size exhibits a limited influence.

A multiscale study of the penetrationenhancing mechanism of menthol

Objective:Transdermal drug delivery systems represent a critical focus in the pharmaceutics field;however,their use is limited by the fact that many drugs usually pass through the skin with low permeability.Menthol is a common penetration enhancer because of its high penetration-enhancing efficiency and safety.Our research aimed to reveal the penetrationenhancing mechanisms of menthol via a multiscale study.Methods:First,the interaction of menthol with the stratum corneum was studied using vertical Franz diffusion cells obtained from the abdominal skin of rats as a model.Then,the skin samples were observed via transmission electron microscopy.Finally,the interaction of different concentrations of menthol with a mixed lipid model of the stratum corneum was investigated via molecular dynamics simulation using the GROMOS 54A7 force field on a microcosmic level.Results:At concentrations of 3.5%or lower,menthol changed the original structure of the stratum corneum to varying degrees,which increased its fluidity and facilitated the permeation and storage of menthol.Menthol increased the fluidity of the stratum corneum mainly via two mechanisms.First,menthol had strong hydrogen-bonding capability,and it could compete for the lipidelipid hydrogen bonding sites,thereby weakening the stability of the hydrogenbonding network connecting the skin lipids.In addition,menthol had strong affinity for cholesterol,probably due to their similar molecular structures,suggesting that the incorporation of menthol would increase the fluidity of the lipid membrane similarly to cholesterol.Conclusion:The penetration-enhancing mechanism of menthol was explained using in vitro and molecular dynamics simulation methods.These findings may advance the basic research of transdermal drug delivery systems and facilitate the discoveries of novel penetration enhancers.

对硝基苯甲酸二丁基锡酸酯的合成与晶体结构

我们利用二丁基氧化锡、对硝基苯甲酸在摩尔比1:2下进行反应合成了化合物Bu2Sn[OOCC6H4(NO2-p)]2。通过元素分析、红外光谱、核磁共振氢谱以及X-射线单晶衍射测定了化合物的结构。该化合物晶体属单斜晶系,空间群Cc,a = 1.5604(5) nm,b = 0.7007(2) nm,c = 2.2816(7) nm;α = 90?,β = 103.599(5)?,γ = 90?;Z = 4,V = 2.4247(13) nm3,Dc = 1.548 mg/m3,μ(MoKα) = 1.102 mm?1,F(000) = 1144,R = 0.0373,wR = 0.0964。该化合物中与锡原子键连的四个氧原子占据了四角双锥的赤道平面,两个丁基碳原子占据轴向位置。其几何形状是变形的四角双锥结构。

Molecular Cloning and Putative Functions of KIFC1 for Acrosome Formation and Nuclear Reshaping during Spermiogenesis in Schlegel’s Japanese Gecko Gekko japonicus

Spermiogenesis, occurring in the male testis, is a complicated and highly-ordered developmental process resulting in the production of fertile mature sperm. In Gekko japonicus, this process occurs in 7 steps during which the spermatids undergo dramatic changes in the cytoskeleton and nucleus. Here, we cloned and sequenced the cDNA of the mammalian KIFC1 homologue in the testis of G. japonicus. The 2 344 bp full-length cDNA sequence contained a 191 bp 5’-untranslated region, a 134 bp 3’-untranslated region and a 2 019 bp open reading frame encoding a protein of 672 amino acids. Tissue expression analysis revealed the highest expression of kifc1 mRNA was in the testis. Fluorescence in situ hybridization revealed that the kifc1 mRNA signal was hardly detected in step 1 spermatids but became concentrated at the acrosome of step 2 spermatids and abundant in the nucleus of step 5 spermatids where the nucleus then undergoes dramatic elongation and compression. The kifc1 mRNA signal then gradually disappears in mature sperm. This expression of KIFC1 at specific stages of spermiogenesis in G. japonicus implies its important role in the major cytological transformations such as acrosome biogenesis and nucleus morphogenesis.

Combinatorial optimization of perovskite-based ferroelectric ceramics for energy storage applications

With the increasing impacts of climate change and resource depletion,dielectric capacitors,with their exceptional stability,fast charging and discharging rates,and ability to operate under more extreme conditions,are emerging as promising high-demand candidates for high-performance energy storage devices,distinguishing them from traditional electrochemical capacitors and batteries.However,due to the shortcomings of various dielectric ceramics(e.g.,paraelectrics(PEs),ferroelectrics(FEs),and antiferroelectrics(AFEs)),their low polarizability,low breakdown strength(BDS),and large hysteresis loss limit their standalone use in the advancement of energy storage ceramics.Therefore,synthesizing novel perovskite-based materials that exhibit high energy density,high energy efficiency,and low loss is crucial for achieving superior energy storage performance.In this review,we outline the recent development of perovskitebased ferroelectric energy storage ceramics from the perspective of combinatorial optimization for tailoring ferroelectric hysteresis loops and comprehensively discuss the properties arising from the different combinations of components.We also provide future guidelines in this realm.Therefore,the combinatorial optimization strategy in this review will open up a practical route toward the application of new high-performance ferroelectric energy storage devices.

Multi-site occupancies and dependent photoluminescence of Ca_(9)Mg_(1.5)(PO_(4))_(7):Eu^(2+) phosphors:A bifunctional platform for optical thermometer and plant growth lighting

Herein,we demonstrate an optical thermometer based on single Eu^(2+)doped Ca_(9)Mg_(1.5)(PO_4)_7 phosphors,which were prepared by traditional solid-state reaction technique under a reduction atmosphere.Considerations on the bond length obtained by the crystal structure refinement and the dependent photoluminescence performances allow to assign the two distinct emission bands to Eu^(2+)ions occupied Cal-Ca3 and Mg2 sites.Moreover,the blue and red emitting bands perfectly match with the photosynthetic action spectrum,which can enhance the indoor plant photosynthesis.The optimal doping content of Eu^(2+)ions in this Ca_(9)Mg_(1.5)(PO_(4))_(7)system is 3 mol%.The corresponding concentration quenching effect is verified as dipole-dipole interaction with the critical distance of 3.315 nm.Furthermore,by exploiting the fluorescence intensity technique,the optical thermal resistance properties of Ca_(9)Mg_(1.5)(PO_4)_7:Eu^(2+)are identified based on the temperature dependent emission spectra in a range of 303-523 K.In detail,the maximum absolute and relative sensitivity S_(a)and S_(r)of Ca_9Mg_(1.5)(PO_(4))_(7):Eu^(2+)thermometer are as high as 0.637%/K and 0.3155 K^(-1),respectively.Consequently,the Eu^(2+)doped Ca_(9)Mg_(1.5)(PO_(4))_(7)phosphors establish a bifunctional platfo rm for both optical the rmometer and plant growth lighting via multi-site occupancies.

A high-tortuosity holey graphene in-situ derived from cytomembrane/cytoderm boosts ultrastable potassium storage

The sluggish K^(+)kinetics and structural instability of the generally-used graphite and other carbon-based materials hinder the development of potassium-ion batteries(PIBs)for high-rate capability and long-term cycling.Herein,inspired by the unique flake structure and chemical composition of cytomembrane and cytoderm,we design high-tortuosity holey graphene as a highly efficient anode for PIBs.The flake cytomembrane and cytoderm shrink into wrinkled morphology during drying and sintering and then convert into high-tortuosity graphene after oxidative exfoliating and thermal reducing process.Mean-while,the proteins,sugars,and glycolipids embedded in cytomembrane and cytoderm can in-situ form nanoholes with highly abundant oxygenic groups and heteroatoms around,which can be easily removed and finally the high-tortuosity holey graphene is obtained after a thermal reducing process.The stress distribution after K^(+)intercalation confirms the optimized release of strain caused by the volume change through the finite element method.Benefiting from the unique nanoholes shortening the ion-diffusion length,the synergy of wrinkled and holey structure stabilizing volume fluctuation,and the enhanced electronic conductivity and specific surface area,the high-tortuosity holey graphene demonstrates high reversible capacities of 410 mAh g^(-1)at 25 mA g^(-1)after 150 cycles and retains 91.5%at 2 A g^(-1)after 2500 cycles.

Simulating Temporally and Spatially Correlated Wind Speed Time Series by Spectral Representation Method

In this paper,it aims to model wind speed time series at multiple sites.The five-parameter Johnson mdistribution is deployed to relate the wind speed at each site to a Gaussian time series,and the resultant-Z(t)dimensional Gaussian stochastic vector process is employed to model the temporal-spatial correlation of mwind speeds at different sites.In general,it is computationally tedious to obtain the autocorrelation functions Z(t)(ACFs)and cross-correlation functions(CCFs)of Z(t),which are different to those of wind speed times series.In order to circumvent this correlation distortion problem,the rank ACF and rank CCF are introduced to Z(t)characterize the temporal-spatial correlation of wind speeds,whereby the ACFs and CCFs of can be analytically obtained.Then,Fourier transformation is implemented to establish the cross-spectral density matrix Z(t)mof,and an analytical approach is proposed to generate samples of wind speeds at different sites.Finally,simulation experiments are performed to check the proposed methods,and the results verify that the five-parameter Johnson distribution can accurately match distribution functions of wind speeds,and the spectral representation method can well reproduce the temporal-spatial correlation of wind speeds.

层状K_(x)MnO_(2)基钾离子电池正极材料的研究现状及发展趋势

钾离子电池具有资源丰富、价格便宜等优点,并且与锂离子电池原理相似,是目前取代锂离子电池成为大型储能系统合适的候选者.正极材料对钾离子电池性能起着关键作用,其中层状K_(x)MnO_(2)基正极材料因其高比容量、环境友好、成本低廉、独特的二维钾离子扩散通道而备受关注.但大尺寸的K^(+)在充放电过程中的反复脱嵌会导致结构破坏,并且Mn^(3+)产生的Jahn-Teller效应导致结构畸变,容量快速下降,商业应用难度较大.本文从K_(x)MnO_(2)材料层状结构调控出发,系统总结了K_(x)MnO_(2)基正极材料的制备方法,重点综述了单金属掺杂、双金属掺杂和碱金属掺杂等三种掺杂改性策略,总结阐述了K_(x)MnO_(2)基正极材料在现阶段研究中存在的主要挑战并进一步展望了其未来发展方向,可望为开发高效稳定的钾离子电池提供理论参考.

Conditional inversion to estimate parameters from eddy-flux observations

Aims Data assimilation is a useful tool to extract information from large datasets of the net ecosystem exchange(NEE)of CO_(2) obtained by eddy-flux measurements.However,the number of parameters in ecosystem models that can be constrained by eddy-flux data is limited by conventional inverse analysis that estimates parameter values based on one-time inversion.This study aimed to improve data assimilation to increase the number of constrained parameters.Methods In this study,we developed conditional Bayesian inversion to maximize the number of parameters to be constrained by NEE data in several steps.In each step,we conducted a Bayesian inversion to constrain parameters.The maximum likelihood estimates of the constrained parameters were then used as prior to fix parameter values in the next step of inversion.The conditional inversion was repeated until there were no more parameters that could be further constrained.We applied the conditional inversion to hourly NEE data from Harvard Forest with a physiologically based ecosystem model.Important Findings Results showed that the conventional inversion method constrained 6 of 16 parameters in the model while the conditional inversion method constrained 13 parameters after six steps.The cost function that indicates mismatch between the modeled and observed data decreased with each step of conditional Bayesian inversion.The Bayesian information criterion also decreased,suggesting reduced information loss with each step of conditional Bayesian inversion.A wavelet analysis reflected that model performance under conditional Bayesian inversion was better than that under conventional inversion at multiple time scales,except for seasonal and half-yearly scales.In addition,our analysis also demonstrated that parameter convergence in a subsequent step of the conditional inversion depended on correlations with the parameters constrained in a previous step.Overall,the conditional Bayesian inversion substantially increased the number of parameters to be constrained by NEE data and can be a powerful tool to be used in data assimilation in ecology.

Porous Si/C composite as anode materials for high-performance rechargeable lithium-ion battery

A novel porous silicon was synthesized through a magnesiothermic reduction method of molecular sieve for the first time, Si/C composite was synthesized by using pitch as carbon source. The porous Si/C composite shows a high initial specific capacity of 2018.5 mAh/g with current density of 0.1 A/g. When the current density increases to 2 A/g, it still exhibits high average specific capacity of 640.3 mAh/g. The porous structure can remit the Si particle pulverization during the lithiation]delithiation process. This article can provide a reference for the research of the porous Si anode for the high performance rechargeable lithium-ion battery.

Preparation,structure,luminescence properties of europium doped zinc spinel structure green-emitting phosphor ZnAl_2O_4:Eu^(2+)

The Zn1-xAl2 O4：xEu2＋ phosphor powders were synthesized by the solid-state reaction method.The synthesis temperature for ZnAl2 O4 was optimized,whereas the phase structure,TEM images,photoluminescence（PL） properties,the concentration quenching mechanism,the fluorescence decay curves,as well as the CIE chromaticity coordinates of the samples were investigated in details.Under the excitation at 379 nm,the phosphor exhibits an asymmetric broad-band green emission with a peak at 532 nm,which is ascribed to the 5 d-4 f transition of Eu2＋.When the doping concentration of Eu2＋ ions is 0.01,the luminescence intensity of the sample reaches the maximum value.It is further proved that the exchange interaction results in the concentration quenching of Eu2＋ in the Zn1-xAl2 O4：xEu2＋ phosphor powders.The thermal quenching property of ZnAl2 O4：Eu2＋phosphor was investigated and the quantum efficiency（QE） values of the selected Zn0.99Al2 O4：0.01 Eu2＋ phosphor was measured and determined as 54.85%.The lifetime of the optimized sample Zn0.99Al2 O4：0.01 Eu2＋ is 3.0852 μs and the CIE coordinate of the sample was calculated as（0.3323,0.5538） with high-color-purity green emission.All properties indicate that the green-emitting ZnAl2 O4：Eu2＋ phosphor powder has potential application in white LEDs.

Preparation and characterization of capric-palmitic-stearic acid ternary eutectic mixture/expanded vermiculite composites as form-stabilized thermal energy storage materials

In this study, a composite of form-stable phase change materials （FSPCMs） were prepared by the incorporation of a eutectic mixture of capric-palmitic-stearic acid （CA-PA-SA） into expanded vermiculite （EV） via vacuum impregnation. In the composites, CA-PA-SA was utilized as a thermal energy storage material, and EV served as the supporting material. X-ray diffraction and Fourier transform infrared spectroscopy results demonstrated that CA-PA-SA and EV in the composites only undergo physical combination, not a chemical reaction. Scanning electron microscopy images indicated that CA-PA-SA is sufficiently absorbed in the expanded vermiculite porous network. According to differential scanning calorimetry results, the 70 wt% CA-PA-SA/EV sample melts at 19.3 ℃ with a latent heat of 117.6J/g and solidifies at 17.1 ℃ with a latent heat of 118.3J/g. Thermal cycling measurements indicated that FSPCMs exhibit adequate stability even after being subjected to 200 melting-freezing cycles. Furthermore, the thermal conductivity of the composites increased by approximately 49.58% with the addition of 5 wt% of Cu powder. Hence, CA-PA-SA/EV FSPCMs are effective latent heat thermal energy storage building materials.

Facile fabrication of branched-chain carbohydrate chips for studying carbohydrate-protein interactions by QCM biosensor

A novel approach for fabricating branched-chain （BC） carbohydrate chips to study carbohydrate-protein interactions using Quartz Crystal Microbalance （QCM） biosensor was developed. This approach utilizes functional alkynyl-branch molecule modified chip surfaces, which through the terminal alkynyl group for covalent linking of unprotected azide-carbohydrates. The unprotected azide-carbohydrates were syhthesized in one-step using 2-azido-l,B-dimethylqmidazolinium as catalyst, avoiding complex chemical modifications. Additionally, the branch surface modified with the carbohydrates not only supplies more specific binding site but also reveals significant cluster effect. To exemplify the sugar cluster effect on BC carbohydrate chips, BC Galactose and Mannose chips prepared in this work were used to determine carbohydrate-lectin interactions using QCM biosensor. The results clearly showed that BC chip significantly improves the detection sensitivity compared with the straight-chain （SC） chip. More importantly, the BC galactose chip sensitivity was enhanced 40% compared with the SC galactose chip.