Effective desalination and anti-biofouling performance via surface immobilized MWCNTs on RO membrane

Desalination is considered a viable method to overcome the issue of water scarcity either from waste water or seawater. For this purpose, this study employed a facile approach to develop surface immobilized oxidized-MWCNTs(o-MWCNTs) onto crosslinked polyvinyl alcohol(PVA) membrane. Firstly, modified polysulphone substrate was synthesized on to which crosslinked PVA layer was spread onto it. PVA layer act as active layer for surface immobilization of o-MWCNTs in varying concentration. The functional group analysis, morphology and roughness of membranes surface was conducted out using FTIR, SEM and AFM respectively. The results showed that modified membranes, immobilized o-MWCNTs enhanced the salt rejection(Na_(2)SO_(4)) upto 99.8%. After contacting with Escherichia coli and Staphylococcus aureus for 2.5 h the bacteria mortalities of the fabricated membrane could reach 96.9%. Furthermore, the antibiofouling tests showed that OP-MWCNTs(1-5) modified membranes have higher anti-biofouling property than the control membrane.

Optimization of Dimples in Microchannel Heat Sink with Impinging Jets Part A： Mathematical Model and the Influence of Dimple Radius

With increasing heat fluxes caused by electronic components, dimples have attracted wide attention by researchers and have been applied to microchannel heat sink in modem advanced cooling technologies. In this work, the combination of dimples, impinging jets and microchannel heat sink was proposed to improve the heat transfer performance on a cooling surface with a constant heat flux 500 W/cm2. A mathematical model was ad- vanced for numerically analyzing the fluid flow and heat transfer characteristics of a microchannel heat sink with impinging jets and dimples （MHSIJD）, and the velocity distribution, pressure drop, and thermal performance of MI-ISIJD were analyzed by varying the radii of dimples. The results showed that the combination of dimples and MHSIJ can achieve excellent heat transfer performance; for the MHSIJD model in this work, the maximum and average temperatures can be as low as 320 K and 305 K, respectively when mass flow rate is 30 g/s; when dimple radius is larger than 0.195 mm, both the heat transfer coefficient and the overall performance h/AP of MHSIJD are higher than those of MHSIJ.

Optimization of Dimples in Microchannel Heat Sink with Impinging Jets-Part B： the Influences of Dimple Height and Arrangement

The combination of a microchannel heat sink with impinging jets and dimples(MHSIJD) can effectively improve the flow and heat transfer performance on the cooling surface of electronic devices with very high heat fluxes. Based on the previous work by analysing the effect of dimple radius on the overall performance of MHSIJD, the effects of dimple height and arrangement were numerically analysed. The velocity distribution, pressure drop, and thermal performance of MHSIJD under various dimple heights and arrangements were presented. The results showed that: MHSIJD with higher dimples had better overall performance with dimple radius being fixed; creating a mismatch between the impinging hole and dimple can solve the issue caused by the drift phenomenon; the mismatch between the impinging hole and dimple did not exhibit better overall performance than a well-matched design.

Local and correlated studies of humidity-mediated ferroelectric thin film surface charge dynamics

Electrochemical phenomena in ferroelectrics are of particular interest for catalysis and sensing applications,with recent studies highlighting the combined role of the ferroelectric polarisation,applied surface voltage and overall switching history.Here,we present a systematic Kelvin probe microscopy study of the effect of relative humidity and polarisation switching history on the surface charge dissipation in ferroelectric Pb(Zr_(0.2)Ti_(0.8))O_(3)thin films.We analyse the interaction of surface charges with ferroelectric domains through the framework of physically constrained unsupervised machine learning matrix factorisation,Dictionary Learning,and reveal a complex interplay of voltage-mediated physical processes underlying the observed signal decays.Additional insight into the observed behaviours is given by a Fitzhugh–Nagumo reaction–diffusion model,highlighting the lateral spread and charge passivation process contributors within the Dictionary Learning analysis.

分子动力学中平行六面体的邻位算法

在分子动力学模拟中,Verlet列表法、元胞链接列表法和其他一些改进的算法已经被用来提高计算效率.然而,这些方法大部分应用在立方体系.本文扩展了原始算法的应用领域,使其适用于NP系综,并可以在外载荷作用下进行系统仿真.此外,对于Metric-tensor的压强算法提出相应的标度矩阵,使得邻位算法可以应用在新的压强算法上.同时,还针对平行六面体盒子提出了一种联合算法.该方法综合了改进的Verlet列表法和元胞列表法的优点,可以快速确定平行六面体盒子中每个原子的邻位原子,从而提高仿真速度.最后,利用Lennard-Jones势函数的分子动力学模拟实验验证了本算法的有效性和正确性.

Smart machine learning or discovering meaningful physical and chemical contributions through dimensional stacking

Despite remarkable advances in characterization techniques of functional materials yielding an ever growing amount of data,the interplay between the physical and chemical phenomena underpinning materials’functionalities is still often poorly understood.Dimensional reduction techniques have been used to tackle the challenge of understanding materials’behavior,leveraging the very large amount of data available.Here,we present a method for applying physical and chemical constraints to dimensional reduction analysis,through dimensional stacking.Compared to traditional,uncorrelated techniques,this approach enables a direct and simultaneous assessment of behaviors across all measurement parameters,through stacking of data along specific dimensions as required by physical or chemical correlations.The proposed method is applied to the nanoscale electromechanical relaxation response in(1−x)PMN-xPT solid solutions,enabling a direct comparison of electric field-and chemical composition-dependent contributors.A poling-like,and a relaxation-like behavior with a domain glass state are identified,and their evolution is tracked across the phase diagram.The proposed dimensional stacking technique,guided by the knowledge of the underlying physics of correlated systems,is valid for the analysis of any multidimensional dataset,opening a spectrum of possibilities for multidisciplinary use.

The neighbor list algorithm for a parallelepiped box in molecular dynamics simulations

In classic molecular dynamics (MD) simulations, the conventional Verlet table, cell linked list and many other techniques have been adopted to increase the computational efficiency. However, these methods are only applicable in cubic systems. In this work, the above techniques along with the metric-tensor method are extended to handle NP ensembles, so that MD simulations can be carried out under the most general loading conditions. In order to do so, a particular spatial Cartesian reference frame is proposed to determine the scaling matrix. Also, a combination method, taking the advantages of the improved Verlet table and cell linked list, is established to identify the neighbor atoms very quickly in a parallelepiped box. An example using Lennard-Jones potential is presented to verify the validity of the proposed algorithm.

Copper telluride with manipulated carrier concentrations for high-performance solid-state thermoelectrics

This study proposed a strategy for effectively diminishing the carrier concentration in Cu_(2)Te by introducing graphene sheets,Based on thermoelectric property measurements and single parabolic band modeling,the incorporated graphene effectively reduced the carrier concentration,not only enhancing the thermoelectric performance of the Cu_(2)Te/graphene composite but also substantially improving its figure of merit up to ~1.47 at 1000 K,which is 268% higher than that of pristine Cu_(2)Te,This study gives an insight into the control of carrier concentration and thermoelectric properties in Cu_(2)Te,and it could be extended to other copper chalcogenides for excellent thermoelectrics.