材料专业留学生阶梯式实践课程的教学实践

在“一带一路”背景下,来华留学生的人数迅猛增加,高校课程教学面临新的挑战。实践教学是材料专业留学生教学体系中的重要组成部分,对提升留学生的动手能力、发现和解决问题的能力至关重要。从留学生实践课程建设的必要性和可行性入手,结合“互联网+”在线教学平台,通过设计课程内容、优化培训模式、建立师资队伍、完善课程评估等举措,探索构建了“阶梯式”的新型培训课程体系,旨在提升留学生实践教学质量,打造品牌专业课程,同时也为其他工科专业留学生的实验教学积累经验。

响应面法优化超临界抗溶剂法制备姜黄素-PLGA复合颗粒

采用超临界二氧化碳抗溶剂法制备聚乳酸-羟基乙酸共聚物(curcumin-encapsulated poly(lactic-co-glycolic acid),PLGA)包埋姜黄素的纳米颗粒。以姜黄素包埋率为优化指标,利用响应面试验设计方法,系统考察芯材比、PLGA溶液流速、超声功率3个因素对PLGA包埋姜黄素的影响。结果表明:当PLGA与姜黄素质量比3:1、PLGA溶液流速1.8 mL/min、超声功率180 W时,包埋率达到93.89%。姜黄素-PLGA颗粒平均粒径为90 nm,粒径分布窄。

Measurement and Correlation of Solid Drugs Solubility in Supercritical Systems

A dynamic experimental set-up was utilized to measure ibuprofen solubility in supercritical CO2 at the pressure range of 8-13 MPa and the temperatures of 308, 313 and 318 K. Mole fraction values varied from 0.015＆#215;10^-3 to 3.261＆#215;10^-3 and correlated by using seven different semi empirical equations of state （Bartle, Modi-fied Bartle, Mendez-Teja, Modified Mendez-Teja, Kumar-Johnson, Sung-shim and Gordillo） as well as seven cubic equations of state （van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, Peng-Robinson, Stryjek-Vera, Patel-Teja-Valderana and Pazuki）. Single and twin-parametric van der Walls mixing rules （vdW1, vdW2） were ap-plied in order to estimate the supercritical solution properties. The physicochemical properties were also obtained using Joback, Lydersen and Ambrose methods. Absolute average relatives deviation （AARD） were calculated and compared for all the correlating systems. Results showed that among the cubic equations of state （EOSs） the Pazuki equation （AARD=19.85% using vdW1 and AARD=8.79% using vdW2） and SRK equation （AARD=19.20%using vdW1 and AARD=10.03%using vdW2） predicted the ibuprofen solubility in supercritical CO2 with the least error in comparison to the others. Among the semi-empirical EOSs the most desirable deviation （AARD〈10%） was obtained by using Modified Bartle and Modified Mendez-Teja equations in all the studied temperatures.

A Posteriori Error Estimate for Streamline Diffusion Method in Soving a Hyperbolic Equation

In this article, we use streamline diffusion method for the linear second order hyperbolic initial-boundary value problem. More specifically, we prove a posteriori error estimates for this method for the linear wave equation. We observe that this error estimates make finite element method increasingly powerful rather than other methods.

The First Integral Method for Solving Maccari’s System

In this paper, we investigate the first integral method for solving the solutions of Maccari’s system. This idea can obtain some exact solutions of this system based on the theory of Commutative algebra.

Measurement and calculation of solubility of quinine in supercritical carbon dioxide

Solubility of quinine in supercritical carbon dioxide(SCCO_2) was experimentally measured in the pressure range of 8 to 24 MPa, at three constant temperatures: 308.15 K, 318.15 K and 328.15 K. Measurement was carried out in a semi-dynamic system. Experimental data were correlated by iso-fugacity model(based on cubic equations of state, CEOS), Modified Mendez–Santiago–Teja(MST) and Modified Bartle semi-empirical models. Two cubic equations of state: Peng–Robinson(PR) and Dashtizadeh–Pazuki–Ghotbi–Taghikhani(DPTG) were adopted for calculation of equilibrium parameters in CEOS modeling. Interaction coefficients(k_(ij)& l_(ij)) of van der Waals(vdW) mixing rules were considered as the correlation parameters in CEOS-based modeling and their contribution to the accuracy of model was investigated. Average Absolute Relative Deviation(AARD) between correlated and experimental data was calculated and compared as the index of validity and accuracy for different modeling systems. In this basis it was realized that the semi-empirical equations especially Modified MST can accurately support the theoretical studies on phase equilibrium behavior of quinine–SCCO_2 media. Among the cubic equations of state DPGT within two-parametric vd W mixing rules provided the best data fitting and PR within one-parametric vd W mixing rules demonstrated the highest deviation respecting to the experimental data. Overall, in each individual modeling system the best fitting was observed on the data points attained at 318 K, which could be perhaps due to the moderate thermodynamic state of supercritical phase.

Intriguing anti-superbug Cu2O@ZrP hybrid nanosheet with enhanced antibacterial performance and weak cytotoxicity

In view of it's strong antibacterial function and minor toxicity,cuprous oxide (Cu2O) is frequently used in various broad-spectrum antibacterial reagents.Nonetheless the undesirable effects of superbugs still remain challenging.In this research,a chemical deposition approach is used to prepare a Cu2O@ZrP composite with nanosheet configuration demonstrating excellent dispersibility and antibacterial traits.From systematic analysis,it was inffered that the content of copper in the nanosheet was about 57-188 mg/g while the average thickness of the nanosheets Cu2O formed on ZrP is approximately 0.8 nm.The results of the minimal inhibitory concentration (MIC) revealed that an extremely low loading of Cu2O in Cu2O@ZrP nanosheet can lead to exceptional antibacterial activity.Examined on two various superbugs;i.e.methicillin-resistant staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE),the composite nanosheet reagent performed over 99% microbial reduction.More intesetingly,the cell growth rate of the Cu2O@ZrP nanosheet was determined to be 20% lower than that of the neat Cu2O,manifesting a weaker cytotoxicity.This unique hybrid nanosheet with intriguing anti-superbug performance promises highly efficient protection for the fabrics,battledress,and medical textiles.

Progress and Perspective of Antiviral Protective Material

Public health events caused by viruses pose a significant risk to humans worldwide.From December 2019 till now,the rampant novel 2019 coronavirus(SAR-CoV-2)has hugely impacted China and over world.Regarding a commendable means of protection,mask technology is relatively mature,though most of the masks cannot effectively resist the viral infections.The key material of the mask is a non-woven material,which makes the barrier of virus through filtration.Due to the lack of the ability to kill the viruses,masks are prone to cross-infection and become an additional source of infection after being discarded.If the filteration and antiviral effects can be simultaneously integrated into the mask,it will be more effcient,work for a longer time and create less difficulty in post-treatment.This mini-review presents the advances in antiviral materials,different mechanisms of their activity,and their potential applications in personal protective fabrics.Furthermore,the article addresses the future challenges and directions of mask technology.

Perovskite Solar Fibers:Current Status,Issues and Challenges

Perovskite-based solar cells with high power conversion efficiencies(PCEs)are currently being demonstrated in solid-state device designs.Their elevated performances can possibly be attained with different non-standard geometries,for example,the fiber-shaped perovskite solar cells,in the light of careful design and engineering.Fiber-shaped solar cells are promising in smart textiles energy harvesting towards next-generation electronic applications and devices.They can be made with facile process and at low cost.Recently,fiber-shaped perovskite solar devices have been reported,particularly with the focus on the proof-of-concept in such non-traditional architectures.In this line,there are so many technical aspects which need to be addressed,if these photovoltaic(PV)cells are to be industrialized and produced massively.Herein,a well-organized and comprehensive discussion about the reported devices in this arena is presented.The challenges that need to be addressed,the possible solutions and the probable applications of these PV cells are also discussed.More still,the perovskite fiber-shaped PV cells with other fiber PV devices reported in literature in terms of their scope,characteristic designs,performances,and other technical considerations have been summarised.

The Crystallization,Melting Behaviors and Thermal Stability of Cross-linked Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Octavinyloctasilasesquioxane

A series of cross-linked poly（3-hydroxybutyrate-co-3-hydroxyvalerate）/octavinyloctasilasesquioxane （PHBWOVS） composites were obtained by a simple melt reactive processing technique. Dicumyl peroxide （DCP） and OVS were employed as a free radical initiator and a cross-linking agent, respectively. The chemical structure of these produced composites were identified by 1H/13C/29Si-nuclear magnetic resonance spectroscopy （1H/13C/29Si-NMR） and Fourier transform infrared spectroscopy （FTIR）. The melting behavior, non-isothermal crystallization, spherulite morphology and thermal stability property of PHBV/OVS composites were also investigated. The nucleation behaviors and crystallization rate of PHBV/OVS were significantly enhanced with the formation of cross-linked networks with different side-chains and cross-linking points. The red shift of crystalline peak temperature with addition of a small amount of OVS content evidenced the higher crystalline ability compared with the neat PHBV. However there was a threshold content, beyond which the crystallization rate weakened again. Additionally, the cross-linked structure of PHBV/OVS composites could be adjusted by changing the amount of OVS.

Enhanced Photocatalytic Performance of Surface-Modified TiO_(2) Nanofibers with Rhodizonic Acid

The improvement of the photocatalytic performance of TiO_(2) nanofibers(NFs),prepared by electrospinning,is achieved by surface modification with the rhodizonic acid(RhA).The condensation reaction between hydroxyl groups from TiO_(2) NFs and RhA is accompanied by the red-shift of optical absorption due to interfacial charge transfer(ICT)complex formation.Crystal structure,morphology,and optical properties of unmodified and surface-modified TiO_(2) NFs were analyzed.The photocatalytic performance of prepared samples has been examined through degradation of organic dye methylene blue.Superior photocatalytic activity of surface-modified TiO_(2) NFs with RhA is attributed to their enhanced optical properties,i.e.,the ability to harvest the photon energy in the visible spectral range.

Transformation of Supercapacitive Charge Storage Behaviour in a Multi elemental Spinel CuMn_(2)O_(4) Nanofibers with Alkaline and Neutral Electrolytes

Electrode material has been cited as one of the most important determining factors in classifying an energy storage system’s charge storage mechanism,i.e.,as battery-type or supercapacitive-type.In this paper,we show that along with the electrode material,the electrolyte also plays a role in determining the charge storage behaviour of the system.For the purpose of our research,we chose multi-elemental spinal type CuMn_(2)O_(4) metal oxide nanofibers to prove the hypothesis.The material is synthesized as nanofibers of diameter~120 to 150 nm in large scales by a pilot scale electrospinning set up.It was then tested in three different electrolytes(1 M KOH,1 M Na_(2)SO_(4) and 1 M Li_(2)SO_(4)),two of which are neutral and the third is alkaline(KOH).The cyclic voltammograms and the galvanostatic charge-discharge of the electrode material in a three-electrode sys-tem measurement showed that it exhibit different charge storage mechanism in different electrolyte solutions.For the neutral electrolytes,a capacitive behaviour was observed whereas a battery-type behaviour was seen for the alkaline electrolyte.This leads us to conclude that the charge storage mechanism,along with the active material,also depends on the electrolyte used.

Intense‑Light Sensing Yarns Achieved by Interfused Inorganic Halide Perovskite Nanofiber Network

Fully inorganic metal halide perovskites(MHPs)demonstrate enhanced stability over their organic–inorganic counterparts,however,their integrations into flexible or textile-based substrates remain a significant challenge,due to their inherent rigidity and the necessity of high-temperature annealing.Herein,we propose a one-step and near-room-temperature electrospinning process to fabricate flexible CsPbI_(2)Br nanofibers that can be directly deposited on the yarns.With the in-situ CsPbI_(2)Br crystallization during electrospinning,annealing-free and photoelectroactiveγ-CsPbI_(2)Br can be achieved.Polyvinyl acetate(PVAc)serves as the carrier polymer to offer the flexibility and facilitate the chemical interaction with CsPbI_(2)Br,thereby mitigating moisture and oxygen-induced degradations.CsPbI_(2)Br-PVAc nanofibers obtained under the optimal electrospinning condition:high-electrospinning voltage(25 kV)and low-solution supply rate(0.02 mm/min),show more uniform morphology,increased stability,and extended photoluminescence decay time.These nanofibers enable the construction of photo-sensing yarn devices,capable of generating a photovoltage of around 180 mV and current density of 17 mA/cm^(2)upon illumination by a 532 nm pulsed laser,while maintaining a remarkable ambient stability of 16 days.Given their laserenergy-dependent voltage output,these yarns hold significant potential for developing high-intensity light-detecting textiles for various applications.