Drying oil-in-water Pickering emulsions to make redispersible powders

We report on the formation of powder by drying oil-in-water emulsions stabilized by silanised silica nanoparticles. Drying was achieved by spraying fine droplets (up to a hundred micrometres in diameter) of the emulsions into a chamber of hot, flowing air. We show that the surfaces of droplets of the emulsions become enriched with nanoparticles as the water evaporates in the drying chamber. Controlling the relative amounts of oil and particles in the droplets being dried is the key to encapsulating the oil drops within the powder. Dried Pickering emulsions containing up to 40 wt% encapsulated oil that could be dispersed in water as drops of the same size as in the original emulsion were produced.     

Topical delivery of fluconazole: in vitro skin penetration and permeation using emulsions as dosage forms

We investigated in vitro skin penetration and permeation of fluconazole from emulsions containing different penetration enhancers. Fluconazole permeation was high (15-65% of the applied dose) across hairless mouse skin and low (8-9%) across pig ear skin. Permeation across mice skin from a formulation containing propyleneglycol and isopropyl myristate was significantly higher than that observed with the paraffin oil and propyleneglycol or Transcutol® emulsions. With pig skin, the paraffin oil or isopropyl myristate and propyleneglycol emulsions showed similar skin permeation and penetration. However, these emulsions provided epidermal concentrations higher than the minimal inhibitory concentrations for most dermatophytes.     

Development of fluorinated polyplex nanoemulsions for improved small interfering RNA delivery and cancer therapy

Nano Research - We report the development of a small interfering RNA (siRNA) delivery vector based on cationic perfluorocarbon nanoemulsions. We have prepared perfluorodecalin (PFD) emulsions with...     

Topical Delivery of Fluconazole: In Vitro Skin Penetration and Permeation Using Emulsions as Dosage Forms

ABSTRACT

We investigated in vitro skin penetration and permeation of fluconazole from emulsions containing different penetration enhancers. Fluconazole permeation was high (15–65% of the applied dose) across hairless mouse skin and low (8–9%) across pig ear skin. Permeation across mice skin from a formulation containing propyleneglycol and isopropyl myristate was significantly higher than that observed with the paraffin oil and propyleneglycol or Transcutol® emulsions. With pig skin, the paraffin oil or isopropyl myristate and propyleneglycol emulsions showed similar skin permeation and penetration. However, these emulsions provided epidermal concentrations higher than the minimal inhibitory concentrations for most dermatophytes.     

Silver halide sensitized gelatin process effects in holographic lenses recorded on Slavich PFG-01 plates

In this work we study the feasibility of using silver halide sensitized gelatin based on PFG-01 (Slavich) emulsions to construct uniaxial compound lenses. This processing is able to introduce variations in the thickness and refractive index of the emulsion. We prove that these changes are not sufficient to provide the observed variations in Bragg conditions in the reconstruction and that a shear-type effect must exist to explain the performance of processed emulsions. We study the characteristics of a compound lens, obtaining acceptable image quality, good resolution, and the typical field limitation of volume holographic elements.     

Design of a Mechanical Tuning for Superconducting Microwave Power Filters

We have been studying microwave superconducting power filters with dynamic tunable mechanism. This paper reports estimation of superconducting microstrip patch resonators using piezoelectric actuators as parts of the electrically tunable mechanism. We carried out electromagnetic (EM) simulations on the proposed tunable patch resonators. The main conditions of the EM simulations were that the superconducting material was YBCO, the patch pattern with TM₁₁ or TM₀₁-resonant mode was disk shape, and so on. From the EM simulation results, it was estimated that the resonant mode differences of the unloaded-Q, the power handling capability, and the resonant frequency tunability related with the PZT bimorph element as the actuator candidate.     

Electromigration in submicron interconnect features of integrated circuits

Electromigration (EM) is a complex multiphysics problem including electrical, thermal, and mechanical aspects. Since the first work on EM was published in 1907, extensive studies on EM have been conducted theoretically, experimentally, and by means of computer simulation. Today EM is the most significant threat for interconnect reliability in high performance integrated circuits.Over years, physicists, material scientists, and engineers have dealt with the EM problem developing different strategies to reduce EM risk and methods for prediction of EM life time. During the same time a significant amount of work has been carried out on fundamentally understanding of EM physics, of the influence of material and geometrical properties on EM, and of the interconnect operating conditions on EM. In parallel to the theoretical studies, a large amount of work has been performed in experimental studies, mostly motivated by urgent and specific problem settings which engineers encounter during their daily work. On the basis of accelerated electromigration tests, various time-to-failure estimation methods with Blacks equation and statistics have been developed. The big question is, however, the usefulness of this work, since most contributions about electromigration and the accompanying stress effects are based on a very simplified picture of electromigration.The intention of this review paper is to present the most important aspects of theoretical and experimental EM investigations together with a brief history of the development of the main concepts and methods. We present an overview of EM models from their origins in classical materials science methods up to the most recent developments for submicron interconnect features, as well as the application of ab initio and first principle methods. The main findings of experimental studies, important for any model development and application, will also be presented.     

Solving the response time variability problem by means of the electromagnetism-like mechanism

The response time variability problem (RTVP) is an NP-hard combinatorial scheduling problem that has been recently formalised in the literature. The RTVP has a wide range of real-life applications such as in the automobile industry, when models to be produced on a mixed-model assembly line have to be sequenced under a just-in-time production. The RTVP occurs whenever products, clients or jobs need to be sequenced so as to minimise variability in the time between the instants at which they receive the necessary resources. In two previous studies, three metaheuristic algorithms (a multi-start, a GRASP and a PSO algorithm) were proposed to solve the RTVP. We propose solving the RTVP by means of the electromagnetism-like mechanism (EM) metaheuristic algorithm. The EM algorithm is based on an analogy with the attraction-repulsion mechanism of the electromagnetism theory, where solutions are moved according to their associated charges. In this paper we compare the proposed EM metaheuristic procedure with the three metaheuristic algorithms aforementioned and it is shown that, on average, the EM procedure improves strongly on the obtained results.     

Water-in-Water Emulsions Stabilized by Silica Janus Nanosheets

Water-in-water (w/w) emulsions have been recognized for their broad applications in foods, cosmetics, and biomedical engineering. In this work, silica Janus nanosheets (JNs) with polyacrylic acid (PAA) chains grafted on one surface via crushing functional silica foams, and used silica JNs as Pickering stabilizer to produce stable water-in-water (w/w) emulsions from the aqueous two-phase system (ATPS) containing methacrylic acid (MAA) and NaCl are prepared. The interfacial area of w/w emulsions increases linearly with the concentration of silica JNs, and the interfacial coverage of nanosheets is calculated to be about 98%. After polymerizing w/w emulsions prepared from MAA/NaCl ATPS, it is found that silica JNs are entrapped at the interface of w/w emulsions with the smooth PAA-grafted surface located toward MAA-rich phase due to their specific interaction. These results show that functional silica JNs can be used as a promising amphiphilic Pickering stabilizer to produce well-defined w/w emulsions for numerous application fields.     

The effect of additives on the treatment of oil-in-water emulsions by vacuum evaporation

A simple batch vacuum evaporation process for the treatment of several oil-in-water (O/W) emulsions is reported. The experiments were carried out with waste emulsions from an industrial copper rolling process and with model emulsions prepared in the laboratory. No detailed information on the formulation of the industrial waste O/W emulsions was available. Several model emulsions were formulated using the same base oil (an 85–15% (w/w) mixture of a synthetic poly-α-olefin and a trimethylol propane trioleate ester, respectively) and one of the three following surfactants: Brij-76 (polyethylene glycol octadecyl ether, non-ionic), CTAB (hexadecyltrimethyl ammonium bromide, cationic), and Oleth-10 (glycolic acid ethoxylate oleyl ether, anionic). Experimental results show a strong influence of operating conditions, such as pressure or bath temperature, on the evaporation performance. As a general trend, the higher the values of these parameters, the higher the pollutant content in the obtained aqueous effluent. The presence of surfactants increase the evaporation rate, especially at low operating vacuum pressures, the solubility of oil molecules in water and the evaporation temperature of model O/W emulsions. Furthermore, COD reductions higher than 99.5% for the treated waste O/W emulsions were achieved.     

Surface plasmon-mediated energy transfer in heterogap Au-Ag nanowires

We report the observation of energy transfer from a gold (Au) nanodisk pair to a silver (Ag) nanowire across a 120 nm gap via surface plasmon resonance (SPR) excitation. The enhanced electromagnetic (EM) fields generated by Au SPR excitation induce oscillation of the conduction electrons in the Ag segment, transferring energy to it even though the Ag segment has only weak resonant interactions with the incident EM radiation. The induced Ag SPR produces strong EM fields at the position of the Ag segment, leading to a Raman signal approximately 15 times greater than when the Ag segment is alone (not adjacent to the Au nanodisk pair). The Raman intensity is found to depend nonlinearly on the incident laser intensity for laser power densities of 10 kW/cm(2), which is consistent with the results of EM theory calculations which are not able to account for the factor of 15 enhancement based on a linear mechanism. This suggests that energy transfer from the Au disk pair to the Ag segment involves an enhanced nonlinear polarization mechanism such as can be produced by the electronic Kerr effect or stimulated Raman scattering.     

Dependence of electromigration caused by different mechanisms on current densities in VLSI interconnects

In this paper, we have studied electromigration (EM) behavior under different current densities experimentally and theoretically. Our experimental results have shown that the dependence of median-time-to-failure on current density is not the same in different regimes of current densities. Both the theoretical analysis and observation of SEM showed that mechanisms causing EM failure in different regimes are different. In the low current density regime EM failure is caused by microstructural changes, while in the high current density regime it is microstructural changes caused by a temperature gradient. We have developed a model to describe the dependence. The calculated results are consistent with experiments.     

Near-Field Electromagnetic Characterization and Perturbation of Logic Circuits

We propose here a nondestructive electromagnetic (EM) near-field test bench for both EM compatibility and susceptibility of circuits. This setup permits both the collection of the near field and injection without contact of a disturbing EM field, all through a probe. Exhaustive characterizations of probes are undertaken via simulations and experiments. According to their design, they are supposedly linked more to the electric or the magnetic field. Simulations of their EM behavior are undergone to fix their optimal geometries, leading to the best measurement performances. It is shown by both the simulations and the S-parameter measurements that their presence does not interfere with the electric behavior of the device under test. Then, logic circuits are characterized from the EM point of view, with the help of this test bench. Circuits are placed on three different printed boards: one double-sided low-frequency board without a ground plane and two single-sided boards with a ground plane and a design that is more or less optimized. EM near-field mappings highlight the strong field areas of the circuits. The need for a ground plane is highlighted. Field patterns on the traces are linked with those observed on microstrip lines. Then, an EM aggression is injected over a supposed sensitive zone of the circuit. Whichever printed board is considered, a parasitic signal superimposes itself on the output signal of the gates. Deepened studies are undergone to exhaustively explain the phenomena observed.     

Emulsification Methods for Perfluorochemicals

Abstract

A comparison of emulsification methods for novel perfluorochemical (PFC) emulsions for biological uses related to oxygen transport has been made. The emulsions were based on perfluorodecalin (FDC) and contained small quantities of polycyclic, perfluorinated, higher boiling point oil (HBPO) additives to stabilise against the process of molecular diffusion known as Ostwald ripening. Emulsification methods studied include sonication and homogenization which produced emulsions having similar particle size distributions. However, sonication generated fluoride (F-) ions which may have adverse physiological effects.     

Investigation of AGFA-8E56HD photographic emulsion and relief hologram structures by atomic force microscopy

Relief holograms are obtained on Agfa 8E56HD holographic emulsions by a Russian chemical-processing technique that is developed for their PE-2 holographic emulsion. We have shown that the three-dimensional surface profiles can easily be visualized by applying atomic force microscopy to measurement of the relief depth and relief spacing on holographic emulsions. The relief depth and thus diffraction efficiency decreases with increasing exposure time.     

Current Trends in Pickering Emulsions: Particle Morphology and Applications

In recent years, Pickering emulsions and their applications have attracted a great deal of attention due to their special features, which include easy preparation and enhanced stability. In contrast to classical emulsions, in Pickering emulsions, solid microparticles or nanoparticles that localize at the interface between liquids are used as stabilizers, instead of surfactants, to enhance the droplet lifetime. Furthermore, Pickering emulsions show higher stability, lower toxicity, and stimuli-responsiveness, compared with emulsions that are stabilized by surfactants. Therefore, they can be considered attractive components for various uses, such as photocatalysis and the preparation of new materials. Moreover, the nanoparticle morphology strongly influences Pickering emulsion stability as well as the potential utilization of such emulsions. Here, we review recent findings concerning Pickering emulsions, with a particular focus on how the nanoparticles morphology (i.e., cube, ellipsoid, nanosheet, sphere, cylinder, rod, peanut) influences the type and stability of such emulsions, and their current applications in different fields such as antibacterial activity, protein recognition, catalysis, photocatalysis, and water purification.     

Offshore versus domestic: Can EM MNCs reach higher R&D quality abroad?

In the current discourse about the technological development of emerging market multinational companies (EM MNCs), the internationalization of research and development (R&D) activities is increasingly discussed as a strategy for catching-up to established MNCs. EM MNCs attempt to use international R&D to tap into technologically superior resources abroad which are not available to them in their home market. This study compares the performance of domestic and offshore R&D activities to look into EM MNCs’ ability to conduct high-quality R&D abroad. We use the Chinese telecommunication equipment manufacturer Huawei as a best practice case study. To map their worldwide patent quality pattern, we propose a multiple-patent-office-approach to ensure a balanced view on their activities with data from SIPO, USPTO and EPO. We also employ three different measures to capture different dimensions of patent quality. The results of the empirical model support the assumption of higher quality for patents with knowledge from advanced offshore locations.     

VAE/PVC-VDC共混乳液的研究

此共混乳液采用乙烯－醋酸乙烯共聚物（ＶＡＥ）乳液和氯乙烯－偏氯乙烯共聚物（ＰＶＣ－ＶＤＣ）乳液以机械共混方法制得。考察了其微观形态、流变性及其成膜后的力学性能等，发现共混乳液具有一定的相容性，其拉伸强度与ＶＡＥ胶膜相比有很大的提高。     

Effect of non-ionic surfactant concentration and type on the formation and stability of W/O/W multiple emulsions: Microscopic and conductometric evaluations

W/O/W multiple emulsions with sodium salicylate as a model drug were prepared and evaluated for the effect of surfactant concentration and type on stability using microscopic and conductometric methods. Primary (W/O) emulsions were prepared with lipophilic surfactants (2-31% W/W relative to the oily phase). W/O/W emulsions were formed by mixing the primary emulsions with solutions containing 0.5 to 2% W/V hydrophilic surfactants. Optimum concentration of the lipophilic surfactant was 26% W/W. The optimum hydrophilic surfactant concentration was 1% W/V. Best stability was achieved with HLB 3.7 lipophilic and HLB 15.6 hydrophilic surfactants.     

Agglomeration control of hydroxyapatite nano-crystals grown in phase-separated microenvironments

Materials synthesis processes that require high temperatures consume large quantities of energy that generate an environmental burden. We attempted to synthesize hydroxyapatite (HAp) nano-crystals without firing or melting. “Water in oil” (W/O) emulsions were employed as microreactors for HAp formation. The surfactant-bounded water mediated HAp crystal nucleation, and HAp nano-crystallites were obtained. The obtained particles were aggregates composed of plate-like nano-crystals and monodisperse tiny crystals. Utilization of the W/O emulsions resulted in tunable nucleation frequency and the reactant provision, and yielded HAp nano-crystals with characteristic agglomeration properties.