Control of Particle Adsorption for Stability of Pickering Emulsions in Microfluidics

Studying the stability of Pickering emulsion is of great interest for applications including catalysis, oil recovery, and cosmetics. Conventional methods emphasize the overall behavior of bulk emulsions and neglect the influence of particle adsorbing dynamics, leading to discrepancies in predicting the shelf‐life of Pickering emulsion–based products. By employing a microfluidic method, the particle adsorption is controlled and the stability of the Pickering emulsions is consequently examined. This approach enables us to elucidate the relationship between the particle adsorption dynamics and the stability of Pickering emulsions on droplet‐level quantitatively. Using oil/water emulsions stabilized by polystyrene nanoparticles as an example, the diffusion‐limited particle adsorption is demonstrated and investigated the stability criteria with respect to particle size, particle concentration, surface chemistry, and ionic strength. This approach offers important insights for application involving Pickering emulsions and provides guidelines to formulate and quantify the Pickering emulsion–based products.     

纳微米颗粒的表面改性及其在Pickering乳液中的应用进展

以固体粒子替代表面活性剂稳定的Pickering乳液,不仅可以赋予乳液许多特殊的性能(电磁和温度感应性能等),还可消除由添加表面活性剂所带来的副作用(过敏性和毒性等),这使得Pickering乳液可以应用到对表面活性物质具有很大限制的生物材料领域。系统综述了常见Pickering乳液用固体粒子,以及为了获得不同类型的乳液而对固体粒子进行表面改性的主要方法,着重归纳了表面改性前亲水性羟基磷灰石(HAp)和改性后疏水性HAp作为颗粒乳化剂稳定的Pickering乳液的类型及其进一步合成的产物。     

The Effect of Particle Morphology on the Physical Stability of Pharmaceutical Powder Mixtures: The Effect of Surface Roughness of the Carrier on the Stability of Ordered Mixtures

The effect of particle morphology of the components on the physical stability of ordered mixtures was determined for a model system comprised of a mixture of micronized aspirin and a monodisperse carrier. Spray-dried lactose, crystallized lactose, microcrystalline cellulose, and dextrate were used as carriers. The surface texture of the carriers was quantified in terms of the ratio of the perimeter of the particles to that of an idealized shape at a constant magnification. Mixtures containing highly textured carriers segregated to a lesser extent than those containing smoother textured carriers. This was postulated to be due to the presence of a higher concentration of surface asperities on the coarse carriers that can constitute potentially strong adhesion sites for the fine component because of their higher energy relative to adjacent areas on the surface. The effect of the addition of a ternary component, magnesium stearate, on the stability of the above mixtures was studied. The observed differences in the segregation response were attributed to electrostatic charge effects.     

Polydisperse Powder Mixtures: Effect of Particle Size and Shape on Mixture Stability

ABSTRACT

The effect of the shape and size of the components on the stability of mixtures was evaluated in binary mixtures of drug and carrier. Aspirin was used as model drug; spray-dried lactose and microcrystalline cellulose were used as carriers. The coefficient of variation (CV) of the drug in the mixture at various time intervals during mixing was used as a measure of homogeneity. The stability of mixtures was assessed under conditions that were conducive to segregation—in this case, prolonged mixing. The pattern of change in CV with time was analyzed in terms of convective, shear, and diffusive mixing stages. The variation resulting from a change in the shape of the carriers was smaller than that resulting from size differences. The segregation rate constant, calculated on the assumption of a first-order mixing process, was found to be larger in mixtures having components of different shape than in mixtures having components of similar shape. In mixtures of micronized drug and carrier, the pattern of change in the CV of drug with mixing time was attributed to the distribution of agglomerates of micronized drug during convective mixing, followed by shearing of agglomerates and, finally, the distribution of the primary particles during diffusive mixing. Mixtures of non-cohesive powders of similar size and shape behaved like random mixtures of non-interacting components.     

软材料表面形貌调控与应用研究进展

自然界不同生物表面形貌的特殊功能与作用吸引了众多学者的研究兴趣,而基于软硬材料层状复合结构的表面形貌调控近年来也成为一个研究热点。本文首先介绍了软材料表面形貌形成的几种常用方法,包括预拉伸法、热处理法、溶剂溶胀法,为表面形貌的产生提供了途径。然后对软材料表面形貌在众多工程领域,包括流体动力学、光学等方面的应用做了简介,为其更广阔的工程应用提供了借鉴。在此基础上,对表面形貌的产生方法以及软材料在表面形貌主动调控方面的应用发展趋势进行了展望。     

Some Applications of Acoustic Emission in Particle Science and Technology

Acoustic emission (AE) has been used in many applications in the field of particle science and technology. AE sensors have been used in particle concentration measurements both in gas-continuous and oil-continuous flows in the oil and gas industry. To avoid formation sand flowing into pipelines, leading to erosion of valves and in many cases even to complete blockage of the flow of oil and gas, AE sensors are almost exclusively used in sand monitoring and control. These are very often among standard sensors stipulated by the operators of oil and gas production facilities in offshore, on shore, and subsea applications. Special types of sensor design have led to easy mounting of these AE sensors, which are very often clamp-on devices. This article presents a brief overview of AE-based particle monitoring in general and focuses on flange-mounted sensors in the monitoring of particle flow. By using two or more AE sensors located suitably in the process line, the particle velocity can also be evaluated, as is shown in examples using correlation in this article. The AE sensors can easily be adapted to detect malfunctioning of the process line, whether pneumatic lines or silos, just by analyzing the time series of signals from strategically based AE sensors along the process lines. Some examples are given based on recent measurement data. Finally, the article presents an overview of possibilities for improved particle flow monitoring using a multisensor suite incorporating AE sensors with other sensors/detectors such as those derived from capacitance, resistance, gamma ray, microwave, and optical devices. Artificial intelligence (AI) techniques, such as fuzzy logic and neural network algorithms, used in handling the data from these sensors lead to faster and more reliable control. Some of these topics are addressed also.     

Some Applications of Acoustic Emission in Particle Science and Technology

Acoustic emission (AE) has been used in many applications in the field of particle science and technology. AE sensors have been used in particle concentration measurements both in gas-continuous and oil-continuous flows in the oil and gas industry. To avoid formation sand flowing into pipelines, leading to erosion of valves and in many cases even to complete blockage of the flow of oil and gas, AE sensors are almost exclusively used in sand monitoring and control. These are very often among standard sensors stipulated by the operators of oil and gas production facilities in offshore, on shore, and subsea applications. Special types of sensor design have led to easy mounting of these AE sensors, which are very often clamp-on devices. This article presents a brief overview of AE-based particle monitoring in general and focuses on flange-mounted sensors in the monitoring of particle flow. By using two or more AE sensors located suitably in the process line, the particle velocity can also be evaluated, as is shown in examples using correlation in this article. The AE sensors can easily be adapted to detect malfunctioning of the process line, whether pneumatic lines or silos, just by analyzing the time series of signals from strategically based AE sensors along the process lines. Some examples are given based on recent measurement data. Finally, the article presents an overview of possibilities for improved particle flow monitoring using a multisensor suite incorporating AE sensors with other sensors/detectors such as those derived from capacitance, resistance, gamma ray, microwave, and optical devices. Artificial intelligence (AI) techniques, such as fuzzy logic and neural network algorithms, used in handling the data from these sensors lead to faster and more reliable control. Some of these topics are addressed also.     

Low-Bandgap Porphyrins for Highly Efficient Organic Solar Cells: Materials,Morphology, and Applications

With developments in materials, thin-film processing, fine-tuning of morphology, and optimization of device fabrication, the performance of organic solar cells (OSCs) has improved markedly in recent years. Designing low-bandgap materials has been a focus in order to maximize solar energy conversion. However, there are only a few successful low-bandgap donor materials developed with near-infrared (NIR) absorption that are well matched to the existing efficient acceptors. Porphyrin has shown great potential as a useful building block for constructing low-bandgap donor materials due to its large conjugated plane and strong absorption. Porphyrin-based donor materials have been shown to contribute to many record-high device efficiencies in small molecule, tandem, ternary, flexible, and OSC/perovskite hybrid solar cells. Specifically, non-fullerene small-molecule solar cells have recently shown a high power conversion efficiency of 12% using low-bandgap porphyrin. All these have validated the great potential of porphyrin derivatives as effective donor materials and made DPPEZnP-TRs a family of best low-bandgap donor materials in the OSC field so far. Here, recent progress in the rational design, morphology, dynamics, and multi-functional applications starting from 2015 will be highlighted to deepen understanding of the structure–property relationship. Finally, some future directions of porphyrin-based OSCs are presented.     

水中脉冲电压放电形成等离子体通道模拟分析

为获得水中纳秒脉冲电压下放电形成等离子体通道的发展过程,建立水中放电流体模型的数学方程,利用COMSOL软件的有限元方法求解二维轴对称情况,模拟出针-板电极之间的电场强度、电子密度、氢离子密度以及氢氧根离子密度等随时间和空间的分布,并研究脉冲电压幅值、电极间距、电导率对这些物理量以及流注形貌的影响。模拟结果表明:针电极尖端的高场强使高纯水产生最初的电离,之后产生的空间电荷进一步加强了流注头部场强,使流注头部向前推进,形成等离子体通道;当针-板电极间距较小和所加脉冲电压幅值相对较低时,电极间只形成单流注通道,且通道内的电场强度与电子密度随着电压幅值的略微升高而增大,呈线性变化;当所加脉冲电压的幅值高到一定程度时,单流注通道出现“分叉”,通道内的电子密度随电压幅值的变化不再是线性的。当针-板电极间距较大时,反应腔内则形成类似于“树枝”状的等离子体通道。当用电导率较高的自来水替代高纯水作为反应介质时,流注头部场强与等离子体通道内的电子密度明显提高。     

Nanotechnologies in Food Science:Applications,Recent Trends,and Future Perspectives

Nanotechnology is a key advanced technology enabling contribution,development,and sustainable impact on food,medicine,and agriculture sectors.Nanomaterials have potential to lead qualitative and quantitative production of healthier,safer,and high-quality functional foods which are perishable or semi-perishable in nature.Nanotechnologies are superior than conventional food processing technologies with increased shelf life of food products,preventing contamination,and production of enhanced food quality.This comprehensive review on nanotechnologies for functional food development describes the current trends and future perspectives of advanced nanomaterials in food sector considering processing,packaging,security,and storage.Applications of nanotechnologies enhance the food bioavailability,taste,texture,and consistency,achieved through modification of particle size,possible cluster formation,and surface charge of food nanomaterials.In addition,the nanodelivery-mediated nutraceuticals,synergistic action of nanomaterials in food protection,and the application of nanosensors in smart food packaging for monitoring the quality of the stored foods and the common methods employed for assessing the impact of nanomaterials in biological systems are also discussed.     

Recent Developments in Graphene‐Based Membranes: Structure,Mass‐Transport Mechanism and Potential Applications

Significant achievements have been made on the development of next‐generation filtration and separation membranes using graphene materials, as graphene‐based membranes can afford numerous novel mass‐transport properties that are not possible in state‐of‐art commercial membranes, making them promising in areas such as membrane separation, water desalination, proton conductors, energy storage and conversion, etc. The latest developments on understanding mass transport through graphene‐based membranes, including perfect graphene lattice, nanoporous graphene and graphene oxide membranes are reviewed here in relation to their potential applications. A summary and outlook is further provided on the opportunities and challenges in this arising field. The aspects discussed may enable researchers to better understand the mass‐transport mechanism and to optimize the synthesis of graphene‐based membranes toward large‐scale production for a wide range of applications.     

Applications of ellipsometry in nanoscale science: Needs, status, achievements and future challenges

This paper provides an overview of the relationship between optical ellipsometric measurements and nanoscale science. This relationship is discussed by analyzing published papers, patents and nanomaterials investigated in laboratories and constituting commercial products. Specific challenges and needs for advancing ellipsometry exploitation in nanotechnology are also discussed in the frame of nanometrology standardization. The ellipsometric characterization of plasmonic gold nanoparticles supported on a silicon substrate is used as an example to discuss various issues related to the optical characterization of nanomaterials, i.e., the detection of buried interfaces, size effects on the dielectric function and the monitoring in real time of nanoparticles growth.     

Ag-modified ZnO nanorods and its dual application in visible light-driven photoelectrochemical water oxidation and photocatalytic dye degradation: A correlation between optical and electrochemical properties

In this work, Ag-ZnO composite was prepared at different weight percentages using a modified hydrothermal method for application to the photoelectrochemical (PEC) water oxidation and photocatalytic dye degradation. The resulting samples were studied using structural, surface, optical and photoelectrochemical (PEC) characterization methods. The surface plasmon resonance (SPR) of the optimal catalyst played an essential role in the synergistic improvement of the optical response and the photoinduced charge carrier separation process. The optimal Ag modified ZnO (3 wt% of Ag) showed superior photocatalytic and water oxidation performance. The inclusion of Ag has also played a vital role in the defect concentration and the Schottky junction at the metal–metal oxide interface. As a result, the PEC behavior of the optimal samples showed drastic improvements in terms of water oxidation current response under visible light illumination. Consequently, the photocatalytic performance of the samples also exhibits a linear relationship with the PEC water oxidation performance. The PEC and photocatalytic performance of the optimal sample showed almost five and seven times superior performance than the pristine ZnO in terms of photocurrent value and rate constant value, respectively. This can be attributed to the existence of the Schottky junction leading to the minimum charge transfer resistance and better charge transport across the interface. The superiority of the optimal sample is explained in terms of the physicochemical properties and electrochemistry of the material. To the best of the authors’ knowledge, this is the first report on the role of optimal Ag content in ZnO for its dual application. The combined study offering complete information, the work provides guidelines for noble metal-modified catalyst research moving forward.     

Hole‐Transfer Dependence on Blend Morphology and Energy Level Alignment in Polymer: ITIC Photovoltaic Materials

Bulk‐heterojunction organic photovoltaic materials containing nonfullerene acceptors (NFAs) have seen remarkable advances in the past year, finally surpassing fullerenes in performance. Indeed, acceptors based on indacenodithiophene (IDT) have become synonymous with high power conversion efficiencies (PCEs). Nevertheless, NFAs have yet to achieve fill factors (FFs) comparable to those of the highest‐performing fullerene‐based materials. To address this seeming anomaly, this study examines a high efficiency IDT‐based acceptor, ITIC , paired with three donor polymers known to achieve high FFs with fullerenes, PTPD3T , PBTI3T , and PBTSA3T . Excellent PCEs up to 8.43% are achieved from PTPD3T:ITIC blends, reflecting good charge transport, optimal morphology, and efficient ITIC to PTPD3T hole‐transfer, as observed by femtosecond transient absorption spectroscopy. Hole‐transfer is observed from ITIC to PBTI3T and PBTSA3T , but less efficiently, reflecting measurably inferior morphology and nonoptimal energy level alignment, resulting in PCEs of 5.34% and 4.65%, respectively. This work demonstrates the importance of proper morphology and kinetics of ITIC → donor polymer hole‐transfer in boosting the performance of polymer: ITIC photovoltaic bulk heterojunction blends.     

25th Anniversary Article: Polymer–Particle Composites: Phase Stability and Applications in Electrochemical Energy Storage

Polymer–particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle‐polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion‐transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions.     

Exploring the Nickel–Graphene Nanocomposite Coatings for Superior Corrosion Resistance: Manipulating the Effect of Deposition Current Density on its Morphology,Mechanical Properties,and Erosion‐Corrosion Performance

The use of graphene‐based composite as anti‐corrosion and protective coatings for metallic materials is still a provocative topic worthy of debate. Nickel–graphene nanocomposite coatings have been successfully fabricated onto the mild steel by electrochemical co‐deposition technique. This research demonstrates the properties of nickel–graphene composite coatings influenced by different electrodeposition current densities. The effect of deposition current density on the; surface morphologies, composition, microstructures, grain sizes, mechanical, and electrochemical properties of the composite coatings are executed. The coarseness of deposited coatings increases with the increasing of deposition current density. The carbon content in the composite coatings increases first and then decreases by further increasing of current density. The improved mechanical properties and superior anti‐corrosion performance of composite coatings are obtained at the peak value of current density of 9 A dm^?2. The incorporation of graphene sheets into nickel metal matrix lead to enhance the micro hardness, surface roughness, and adhesion strength of produced composite coatings. Furthermore, the presence of graphene in composite coating exhibits the reduced grain sizes and the enhanced erosion–corrosion resistance properties.

     

Microfluidic‐Based Approaches in Targeted Cell/Particle Separation Based on Physical Properties: Fundamentals and Applications

Cell separation is a key step in many biomedical research areas including biotechnology, cancer research, regenerative medicine, and drug discovery. While conventional cell sorting approaches have led to high‐efficiency sorting by exploiting the cell's specific properties, microfluidics has shown great promise in cell separation by exploiting different physical principles and using different properties of the cells. In particular, label‐free cell separation techniques are highly recommended to minimize cell damage and avoid costly and labor‐intensive steps of labeling molecular signatures of cells. In general, microfluidic‐based cell sorting approaches can separate cells using “intrinsic” (e.g., fluid dynamic forces) versus “extrinsic” external forces (e.g., magnetic, electric field, etc.) and by using different properties of cells including size, density, deformability, shape, as well as electrical, magnetic, and compressibility/acoustic properties to select target cells from a heterogeneous cell population. In this work, principles and applications of the most commonly used label‐free microfluidic‐based cell separation methods are described. In particular, applications of microfluidic methods for the separation of circulating tumor cells, blood cells, immune cells, stem cells, and other biological cells are summarized. Computational approaches complementing such microfluidic methods are also explained. Finally, challenges and perspectives to further develop microfluidic‐based cell separation methods are discussed.     

Genetic Algorithms Applied to Li+ Ions Contained in Carbon Nanotubes: An Investigation Using Particle Swarm Optimization and Differential Evolution Along with Molecular Dynamics

Empirical potentials based upon two and three body interactions were applied to the Li⁺-C system, assuming the Li⁺ ions to be distributed inside high-symmetry, single walled carbon nanotubes of different chirality. Structural optimizations for various assemblages were conducted using evolutionary and genetic algorithms, where differential evolution and particle swarm optimization techniques worked satisfactorily. The results were compared with the outcome of some rigorous molecular dynamics simulations. The potential for using the carbon nanotubes in the negative electrode of lithium ion batteries was also critically examined.     

Ce3+共掺杂对Y2O3:Eu3+荧光粉的发光性能和颗粒形貌的影响

采用化学反应与高温固相反应相结合的方法制备了Ce3和Eu3+共掺杂Y2O3荧光粉,利用X射线衍射和扫描电镜分析,发现Ce3+离子共掺杂对Y2O3:Eu3+荧光粉的颗粒形貌有显著的影响,随着Ce3+离子浓度的改变,形貌可从球型转变为管状.荧光光谱分析表明,所制备的共掺杂荧光粉主要发射位于614纳米的红光峰和位于587纳米...