Thermal transport in composition graded silicene/germanene heterostructures

Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,we investigated the influence of composition gradient length and heterogeneous particles at the silicene/germanene(SIL/GER)heterostructure interface on heat conduction.Our results indicate that composition graded interface at the interface diminishes the thermal conductivity of the heterostructure,with a further reduction observed as the length increases,while the effect of the heterogeneous particles can be considered negligible.To unveil the influence of composition graded interface on thermal transport,we conducted phonon analysis and identified the presence of phonon localization within the interface composition graded region.Through these analyses,we have determined that the decrease in thermal conductivity is correlated with phonon localization within the heterostructure,where a stronger degree of phonon localization signifies poorer thermal conductivity in the material.Our research findings not only contribute to understanding the impact of interface gradient-induced phonon localization on thermal transport but also offer insights into the modulation of thermal conductivity in heterostructures.

Self-Modifying Nanointerface Driving Ultrahigh Bidirectional Thermal Conductivity Boron Nitride-Based Composite Flexible Films

While boron nitride(BN) is widely recognized as the most promising thermally conductive filler for rapidly developing high-power electronic devices due to its excellent thermal conductivity and dielectric properties,a great challenge is the poor vertical thermal conductivity when embedded in composites owing to the poor interracial interaction causing severe phonon scattering.Here,we report a novel surface modification strategy called the "self-modified nanointerface" using BN nanocrystals(BNNCs) to efficiently link the interface between BN and the polymer matrix.Combining with ice-press assembly method,an only 25 wt% BNembedded composite film can not only possess an in-plane thermal conductivity of 20.3 W m-1K-1but also,more importantly,achieve a through-plane thermal conductivity as high as 21.3 W m-1K-1,which is more than twice the reported maximum due to the ideal phonon spectrum matching between BNNCs and BN fillers,the strong interaction between the self-modified fillers and polymer matrix,as well as ladder-structured BN skeleton.The excellent thermal conductivity has been verified by theoretical calculations and the heat dissipation of a CPU.This study provides an innovative design principle to tailor composite interfaces and opens up a new path to develop high-performance composites.

Pilot-scale acetone-butanol-ethanol fermentation from corn stover

Biobutanol is an advanced biofuel that can be produced from excess lignocellulose via acetone-butanol-ethanol(ABE)fermentation.Although significant technological progress has been made in this field,attempts at largescale lignocellulosic ABE production remain scarce.In this study,1m^(3)scale ABE fermentation was investigated using high inhibitor tolerance Clostridium acetobutylicum ABE-P1201 and steam-exploded corn stover hydrolysate(SECSH).Before expanding the fermentation scale,the detoxification process for SECSH was simplified by process engineering.Results revealed that appropriate pH management during the fed-batch cultivation could largely decrease the inhibition of the toxic components in undetoxified SECSH to the solventogenesis phase of the ABE-P1201 strains,avoiding“acid crash”.Therefore,after naturalizing the pH by Ca(OH)_(2),the undetoxified SECSH,without removal of the solid components,reached 17.68±1.30 g/L of ABE production with 0.34±0.01 g/g of yield in 1 L scale bioreactor.Based on this strategy,the fermentation scale gradually expanded from laboratory-scale apparatus to pilot-scale bioreactors.Finally,17.05±1.20 g/L of ABE titer and 0.32±0.01 g/g of ABE yield were realized in 1m3 bioreactor,corresponding to approximately 145 kg of ABE production from 1 t of dry corn stover.The pilot-scale ABE fermentation demonstrated excellent stability during repeated operations.This study provided a simplified ABE fermentation strategy and verified the feasibility of the pilot process,providing tremendous significance and a solid foundation for the future industrialization of second-generation ABE plants.

通过共热解萘和^(13)CHCl_(3)标记C_(60)的形成

在众多多环芳烃(PAHs)中,萘是唯一能够独立拼接形成C_(60)的分子结构,然而,萘在热解过程中如何演变成C_(60)尚不清楚.本文通过13C同位素标记法,利用超高温闪蒸真空热解(UT-FVP)装置共同热解萘与13CHCL3来研究萘辛基聚合反应形成C_(60)的过程.研究结果表明,在1560℃热解温度条件下1~4个完整的10-碳萘骨架单元(C10)可以参与到C_(60)的形成,但随着参与的C10萘骨架单元数量的增加,通过萘辛基聚合路径生成的C_(60)含量降低.在1900℃的热解温度下,萘分子倾向于裂解成小碳簇或者单碳原子,并通过小分子聚集形成C_(60),通过萘辛基聚合反应路径生成C_(60)的比例下降.本研究进一步深入阐述了萘在高温条件下通过萘辛基聚合反应路径生成C_(60)的特点,是对富勒烯“自下而上”生长道路的补充.该发现对于进一步理解富勒烯的形成具有特殊意义.

An ADMM-based parallel algorithm for solving traffic assignment problem with elastic demand

Efficiently solving the user equilibrium traffic assignment problem with elastic demand(UE-TAPED)for transportation networks is a critical problem for transportation studies.Most existing UE-TAPED algorithms are designed using a sequential computing scheme,which cannot take advantage of advanced parallel computing power.Therefore,this study focuses on model decomposition and parallelization,proposing an origin-based formulation for UE-TAPED and proving an equivalent reformulation of the original problem.Furthermore,the alternative direction method of multipliers(ADMM)is employed to decompose the original problem into independent link-based subproblems,which can solve large-scale problems with small storage space.In addition,to enhance the efficiency of our algorithm,the parallel computing technology with optimal parallel computing schedule is implemented to solve the link-based subproblems.Numerical experiments are performed to validate the computation efficiency of the proposed parallel algorithm.

Influence of zeta potential on the flocculation of cyanobacteria cells using chitosan modified soil

Using chitosan modified soil to flocculate and sediment algal cells has been considered as a promising strategy to combat cyanobacteria blooms in natural waters. However, the flocculation efficiency often varies with algal cells with different zeta potential（ZP） attributed to different growth phases or water conditions. This article investigated the relationship between ZP of Microcystis aeruginosa and its influence to the flocculation efficiency using chitosan modified soil. Results suggested that the optimal removal efficiency was obtained when the ZP was between- 20.7 and- 6.7 m V with a removal efficiency of more than 80% in 30 min and large floc size of 〉 350 μm. When the algal cells were more negatively charged than- 20.7 m V, the effect of chitosan modified soil was depressed（〈 60%） due to the insufficient charge density of chitosan to neutralize and destabilize the algal suspension. When the algal cells were less negative than- 6.7 m V or even positively charged, a small floc size（〈 120 μm） was formed, which may be difficult to sink under natural water conditions. Therefore, manipulation of ZP provided a viable tool to improve the flocculation efficiency of chitosan modified soil and an important guidance for practical engineering of cyanobacteria bloom control.

Heavy metal distribution of natural and reclaimed tidal riparian wetlands in south estuary, China

We evaluated the distribution and accumulation of Cd, Cr, Cu, Ni, Pb and Zn in two plant species （Scirpus tripueter Linn. and Cyperus malaccensis Lam.）, in water and soils sampled from the reclaimed tidal riparian wetlands （RTRWs） and the natural riparian wetlands （NRWs） in the Pearl River Estuary （PRE）. The results showed that the concentrations of studied heavy metals in soils exceeded the eco-toxic threshold recommended by US EPA. The concentrations of Cd, Cr and Zn in plants may lead to toxic effiects. The heavy metal concentrations were high in water and low in soils of RTRWs compared with that in the NRWs. The accumulation of heavy metals in the roots of plants was higher in NRWs than those in RTRWs while the opposite result was found for heavy metal accumulation in shoots. Based on the bioaccumulation and translocation factors, the plants in NRWs had a higher capacity to accumulate heavy metals while higher abilities to transport heavy metals from roots to shoots were observed in RTRWs. Heavy metal contaminations in RTRWs were dominated by anthropogenic sources from both side uplands and river water, whereas in NRWs, the metal accumulations were simultaneously affected by anthropogenic and natural factors

Size-self-adaptive recognition method of vehicle manufacturer logos based on feature extraction and SVM classifier

Besides their decorative purposes,vehicle manufacturer logos can provide rich information for vehicle verification and classification in many applications such as security and information retrieval.However,unlike the license plate,which is designed for identification purposes,vehicle manufacturer logos are mainly designed for decorative purposes such that they might lack discriminative features themselves.Moreover,in practical applications,the vehicle manufacturer logos captured by a fixed camera vary in size.For these reasons,detection and recognition of vehicle manufacturer logos are very challenging but crucial problems to tackle.In this paper,based on preparatory works on logo localization and image segmentation,we propose a size-self-adaptive method to recognize vehicle manufacturer logos based on feature extraction and support vector machine(SVM)classifier.The experimental results demonstrate that the proposed method is more effective and robust in dealing with the recognition problem of vehicle logos in different sizes.Moreover,it has a good performance both in preciseness and speed.