Influence of the homogenisation procedure on the physicochemical properties of PLGA nanoparticles

Pilocarpine HCl-loaded PLGA nanoparticles were prepared by emulsification solvent evaporation. Three different stabilisers, polyvinylalcohol (PVA), Carbopol and Poloxamer were used, as well as mixtures thereof. The influence of the homogenisation pressure and number of cycles on the properties of nanoparticles were studied. Particle size was shown to depend on the stabiliser used. An increase of the homogenisation pressure or the number of cycles resulted in a decrease in particle size. The zeta potential value was influenced mainly by the nature of the stabiliser. Particles stabilised with poloxamer or PVA showed a slightly negative zeta potential value, while samples stabilised with carbopol possessed a more negative zeta potential, which became less negative after homogenisation. Drug encapsulation depended strongly on the stabiliser used. The higher drug entrapment of the carbopol-stabilised particles could be explained by an electrostatic interaction between the negatively charged carboxyl groups of carbopol and the positively charged, protonated pilocarpine. The drug release patterns of the particles prepared were quite similar. Differences between the release patterns of the homogenised particles could be attributed both to differences in size as well as drug encapsulation. Turbidimetric measurements suggested an interaction between mucin and PLGA nanoparticles exclusively stabilised with Carbopol.     

Influence of the physicochemical treatment procedure on the morphology and properties of the polyvinyl chloride film surface

Atomic-force microscopy was applied to examination of the topography of the surface of polyvinyl chloride films treated by corona discharge and nitrogen-oxygen plasma at atmospheric pressure. The structure of the modified surface was examined, as well as the influence of the surface activation method on the possibility of its subsequent chemicophysical functionalization.     

Synthesis and physicochemical properties of calcium hydroxylapatite/multi-walled carbon nanotubes nanocomposites

Calcium hydroxylapatite/carbon nanotubes (HA/CNT) composites with various CNT contents have been synthesized by coprecipitation from aqueous solutions in the CaCl₂-(NH₄)₂HPO₄-NH₃-CNT-H₂O system (25°C) under conditions modeling the interaction between HA (Ca₁₀(PO₄)₆(OH)₂), which is an inorganic component of osseous tissue, and multi-walled CNTs. The empirical formula of the composites is Ca₁₀(PO₄)₆(OH)₂ · nCNT · 6H₂O, where n = 0.2?C5.0. The synthesis products have been identified by the solubility (Tananaev??s residual concentration) method, pH measurements, chemical analysis, X-ray diffraction, IR spectroscopy, electron spectroscopy for chemical analysis, and scanning and transmission electron microscopy. The effect of the CNT concentration in aqueous solution on the composition of the HA/CNT composites and on the crystallographic and morphological characteristics of HA nanocrystals in HA/CNT has been investigated.     

Structure and dehydration of hydrous tin dioxide xerogel

Hydrous tin dioxide xerogel with the composition SnO2 · 1.75H₂O is built of tin-oxygen-hydroxide fragments. Water molecules (no more than 1 mol) in the grain structure are kept by hydrogen bonds. Xerogel is dehydrated in the range 50–890°C in two stages. Below 123°C, molecular water is removed and the polycondensation of ≡Sn-O(H)-Sn≡ bridge groups occurs. There also takes place the transition of some water molecules from the molecular to hydroxide form as follows: ≡Sn-O-Sn≡ + H₂O → 2≡Sn-O-H. All processes occur within individual grains. Above 123°C, water removal is due to the polycondensation of tin-oxygen groups. As a result, grains are coarsen. After 200°C, their structure is determined as cassiterite coated by tin oxyhydrate.     

Synthesis and physicochemical characterization of carboxymethylcellulose-containing calcium hydroxylapatite

The CaCl₂-(NH₄)₂HPO₄-C₈H₁₁O₇Na-NH₃-H₂O system was studied at 25°C using the solubility method (Tananaev’s residual concentration method) and pH measurements. The solid phases isolated from the system were characterized using chemical analysis, X-ray powder diffraction, IR spectroscopy, and thermogravimetry. Nanocrystalline carboxymethylcellulose-containing calcium hydroxylapatites Ca₁₀(PO₄)₆(OH)₂ · xH₂O · yC₈H₁₁O₇Na with x = 6–12 and y = 0.1–0.5 were found as a result of the characterization.     

Influence of physicochemical properties of solvents on swelling behavior of fluoropolymers

The experimental data are available on the swelling of carbon-black-filled fluorine-containing polymers (Viton) in a number of solvents. However, the quantitative relation between the physicochemical parameters of the solvents and the degree of swelling of the polymers is still unclear. It has been shown that this relation may be determined in terms of the linear free energy concept via solvation of linear equations with due regard for various characteristics of solvents. The polarizability and basicity of solvents are factors governing the degree of polymer swelling. This fact makes it possible to assume the existence of donor-acceptor interaction between fluorine atoms and donor solvents.     

Influence of sodium dodecyl sulfate on the physicochemical properties of whey protein-stabilized emulsions

The influence of sodium dodecyl sulfate (SDS) on the flocculation of droplets in 20 wt.% soybean oil-in-water emulsions stabilized by whey protein isolate (WPI) was investigated by light scattering, rheology and creaming measurements. The SDS concentrations used were low enough to prevent depletion flocculation by surfactant micelles and extensive protein displacement. In the absence of SDS, emulsions were prone to droplet flocculation near the isoelectric point of the proteins (4<pH<6), but were stable at a higher and lower pH. Flocculation led to an increase in emulsion viscosity, pronounced shear thinning behavior and accelerated creaming. When the surfactant-to-protein molar ratio was increased from 0 to 10, the emulsion instability range shifted to lower pH values due to binding of the negatively charged SDS molecules to the droplets. Our results indicate that the physicochemical properties of protein-stabilized emulsions can be modified by utilizing surfactant–protein interactions.     

Influence of atmospheric plasma on physicochemical properties of vapor-grown graphite nanofibers

Vapor-grown graphite nanofibers (GNFs) were modified by plasma treatments using low-pressure plasmas with different gases (Ar gas only and/or Ar/O2 gases), flow rates, pressures, and powers. Surface characterizations and morphologies of the GNFs after plasma treatment were investigated by X-ray photoelectron spectroscopy (XPS), contact angle, titration, and transmission electron microscopy (TEM) measurements. Also, the investigation of thermomechanical behavior and impact strengths of the GNFs/epoxy composites was performed by dynamic-mechanical thermal analysis (DMTA) and Izod impact testing, respectively. The plasma treatment of the fibers changed the surface morphologies by forming a layer with a thickness on the order of 1 nm, mainly consisting of oxygen functional groups such as hydroxyl, carbonyl, and carboxyl groups. After functionalization of the complete surfaces, further plasma treatment did not enhance the superficial oxygen content but slightly changed the portions of the functional groups. Also, the composites with plasma-treated GNFs showed an increase in T(g) and impact strength compared to the composites containing the same amount of plasma-untreated GNFs.     

Influence of thermal degradation in the physicochemical properties of fish oil

Physicochemical and thermal analyses were undertaken to evaluate the influence of the temperature on the oxidation of sea fish oil once its polyunsaturated fatty acids deteriorate rapidly. Fish oil displayed four decomposition steps in synthetic air atmosphere and only one step in nitrogen atmosphere. The first step started at 189 and 222 °C for oxidizing and inert atmospheres, respectively. An OIT value of 53 min was measured at 100 °C. After the degradation process the peroxide index and the iodine index reduced from 35.38 to 9.85 meq × 1000 g^?1 and from 139.79 to 120.19 gI₂ × 100 g^?1, respectively. An increase of the free fatty acids amount from 0.07 to 0.17% was observed while viscosity increased from 57.2 to 58.0 cP. Absorption at 272 nm also increased. The thermogravimetric and spectroscopic techniques are reproducible and versatile being an option for characterization of edible oil oxidation.     

Influence of maturation conditions of hydroxyapatite gel on the composition of xerogel

The influence exerted by conditions of the secondary maturation of hydroxyapatite gel on the composition of a xerogel was determined. It was found that the prolonged stage of the secondary maturation within pH 7.6–7.1, the low pH value of distilled water or a solution of the acid (HCl, H₃PO₄) and the long time of contact of the hydoxyapatite gel with the acid solution assist the formation of α-tricalcium phosphate impurity. A singlephase hydroxyapatite is formed in the presence of distilled water with pH 5.3–5.6, as the time of the secondary stage of maturation of hydroxyapatite gel within pH 7.6–7.1 is decreased and the total washing time is decreased up to 34–40 days.     

Influence of the parameters of integrated mechanothermochemical reclaiming on the physicochemical properties of vulcanized rubbers

The influence of integrated reclaiming of vulcanized rubbers, combining the high-temperature mechanothermochemical and steam degradation methods, on the properties of reclaims was elucidated.     

Influence of oxidation,hydroxymethylation and sulfomethylation on the physicochemical properties of calcium lignosulfonate

The oxidation, hydroxymethylation and sulfomethylation of calcium lignosulfonate (CLS) were carried out in alkaline medium. Different physicochemical properties of the three reaction samples were determined. Results show that all the three treatments increase the adsorption capacity of CLS, and the absorbed amount of CLS on the surface of cement particles is 1.2 times, 6.9 times and 7.5 times, respectively, larger than that of not reacted one after sulfomethylation, hydroxymethylation and oxidation. The influences of three reactions on the surface activity, foaming ability, complexing property and dispersive performance of CLS are different. The first three properties can be strongly improved by hydroxymethylation but the dispersive performance is weakened. Oxidation has an adverse influence compared to hydroxymethylation. Sulfomethylation only enhances the dispersive performance and has little effect on other properties. Results also indicate that the presence of large amounts of hydroxyl group is the main reason that CLS has complexation property.     

Influence of the silver ions on the physicochemical properties of methyl methacrylate-methacrylic acid copolymer films

The effect of silver ions on the physicochemical properties of methyl methacrylate-methacrylic acid copolymer films, namely, film-forming properties and resistance to fluorine-containing plasma, acid etchers, and temperature, was studied by lithography, derivatography, atomic-force microscopy, and optical spectroscopy. The activation energies were calculated for thermal transformations in the copolymer with and without silver ion additions, when heated in air to 300°C.     

煤粉物化特性对燃烧后灰颗粒物的影响

以三种煤粉在沉降炉中做燃烧实验,用Andersen粒子撞击器分离并捕集燃烧后的灰颗粒物,借助于压汞仪、扫描电镜及能谱、ICP-AES等对煤粉及分级颗粒物进行检测,研究煤粉物化特性对灰颗粒物的粒径分布、形貌、组成、痕量元素的富集等特性的影响。结果表明,煤粉孔结构、组分的赋存方式及含量等影响其破碎行为及组分迁移、转化的过程...     

Influence of the preparation procedure on the properties of polyaniline based magnetic composites

A versatile process for the preparation of composite films consisting of magnetite (Fe₃O₄) nanoparticles embedded in a polyaniline (PANI) matrix is reported. Spectroscopic properties of polyaniline matrix (PANI-EB), polyaniline protonated with camphor sulfonic acid (PANI-CSA_0.5) PANI-ES and PANI/Fe₃O₄-CSA_0.5 composites were studied, both in the state of the solutions of m-cresol and in thin films processed from the same solvents. The results of these studies indicate that m-cresol can be used for PANI/Fe₃O₄ composite preparation. Such films show both reasonably high electrical conductivity and magnetic permeability. A controlled application of a magnetic field during the casting process resulted in the formation of the materials with an unusual combination of magnetic and transport properties. The obtained films show the behavior that can be explained by the presence of both ferromagnetic and paramagnetic phases. The superparamagnetic contribution, if any, is very small. Application of the external magnetic field during fabrication of the composites stimulates creation of the aggregates of magnetic particles which, although keeps conductivity at a relatively high level, leads to a small decrease of the conductivity value.     

Research on the electrochromic properties of Mxene intercalated vanadium pentoxide xerogel films

Journal of Solid State Electrochemistry - Vanadium pentoxide (V2O5) is one of the most popular electrochromic material for electrochromic devices due to its excellent storage capacity of lithium...     

金属核及氧化铈的物理化学性质对一氧化碳氧化的影响

氧化铈独特的氧化还原性能使其适合用作氧化反应中的催化剂或载体.氧化铈负载的过渡金属纳米粒子或孤立的单原子提供了金属-载体界面,从而降低了去除界面氧原子的能耗,提供了可以参与ManVanKulvian氧化过程的活性氧物种.CO氧化是测试氧化铈负载催化剂还原性的主要探针反应,并且它常见于在相对低温下消除CO的各种应用中.在过量H2中优先氧化CO(PROX)反应可控制CO浓度达到超低水平,以防止氢氧化电催化剂中毒.催化剂在CO氧化反应中的活性和在PROX反应中对CO和H2的选择性取决于金属物种的种类和分散性、CeO2的结构和化学性质以及催化剂的合成方法.在这篇综述中,我们总结了最近发表的关于CeO2负载的金属纳米粒子和单原子催化CO氧化和PROX反应的相关工作;以及不同的负载金属和同种金属在普通CeO2表面上的反应性.我们还总结了密度泛函理论计算中提出的最可能的反应机理;并且讨论了各种负载型金属在PROX反应中影响CO氧化选择性的因素.     

Influence of synthesis methods on ettringite dehydration

Journal of Thermal Analysis and Calorimetry - Ettringite is an important cement hydration product and has a significant effect on cement performance. H-ettringite (synthesized by hydration...     

Comparison of different soft chemical routes synthesis of nanocrystalline LiMn2O4 and their influence on its physicochemical properties

A comparative study of nanocrystalline spinel LiMn₂O₄ powders prepared by two different soft chemical routes such as solution and sol-gel methods using lithium and manganese acetates are the precursors under different calcination temperatures. The dependence of the physicochemical properties of the spinel LiMn₂O₄ powder has been extensively investigated by using thermal analysis (TGA/DTA), FTIR, X-ray diffraction studies, SEM, specific surface area (BET) and electrical conductivity measurements. The results show that pure LiMn₂O₄ can be prepared from acetate precursors as starting materials at a low temperature of 600°C from solution route and 500°C from sol-gel method. The charge-discharge characteristics and the cycling behavior of Li/1M LiBF₄-EC/DEC electrolyte / LiMn₂O₄cells revealed that LiMn₂O₄ calcined at higher temperatures showed a high initial capacity, while the LiMn₂O₄calcined at lower temperatures exhibited a good cycling behavior.