Effect of Mechanochemical Processing on Illite Particles

Dry grinding of illite particles has been investigated by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and nitrogen adsorption techniques. Prolonged grinding results in an amorphous illite structure and the mechanochemical effect markedly promotes a reduction in reflection intensities with increased grinding time. It is confirmed that illite is very susceptible to alteration by grinding. The illite crystal size (d₀₀₆) appears to reach a limit after 2 h of grinding. N₂ adsorption studies indicate that illite ground for 8 h shows a larger average pore diameter than a sample after 4 h grinding or the original illite. It is inferred that grinding is good for the formation of macrostructural pores. Illite grinding results in a decrease in the Brunauer‐Emmet‐Teller (BET) surface area and total pore volume. IR spectroscopy shows a slight alteration in the illite bands after mechanochemical processing and some new bands were detected after 4 or more hours of grinding.     

黄铜矿在水溶液中的溶解特性和表面性质谱学表征

根据黄铜矿的X射线粉末衍射图谱建立了晶体结构模型,应用ICP-MS,AFM和XPS分析研究了黄铜矿在氩气与氧气环境中不同机械搅拌时间和不同pH值水溶液中的溶解特性和表面性质,建立了黄铜矿在水溶液中的溶解模型。实验结果表明,在纯水中,溶液中的铜和铁的浓度与时间的关系可定义为方程c=ksat+b;低pH值有利于黄铜矿的溶解;表面氧化缓慢,对黄铜矿溶解性影响微弱;纯水中黄铜矿的溶解性对有效比表面积影响不大,酸性条件下黄铜矿的溶解由表面化学反应控制;长时间溶解后黄铜矿表面呈富铜状态;溶解使表面粗糙度和晶格缺陷增加。     

Curing properties of furfuryl alcohol condensate with carbonaceous fine particles under ultrasonication

Ultrasonic treatment (sonication) was carried out through the curing process of furan resin by using an ultrasonic homogenizer at the frequency of 20 kHz and the various intensities (0-90 W). Various carbonaceous fine particles were added to furan resin to investigate the change of polymerization degree. The curing rate of furan resin was accelerated by sonication, which increased the polymerization degree with an increase in ultrasound intensity. The increase of curing rate was also observed by small additions of carbonaceous fine particles. In this case, the curing rate was increased with an increase in the specific surface area on additives.     

Formulation of poorly water-soluble Gemfibrozil applying power ultrasound

The dissolution properties of a drug and its release from the dosage form have a basic impact on its bioavailability. Solubility problems are a major challenge for the pharmaceutical industry as concerns the development of new pharmaceutical products. Formulation problems may possibly be overcome by modification of particle size and morphology. The application of power ultrasound is a novel possibility in drug formulation. This article reports on solvent diffusion and melt emulsification, as new methods supplemented with drying in the field of sonocrystallization of poorly water-soluble Gemfibrozil. During thermoanalytical characterization, a modified structure was detected. The specific surface area of the drug was increased following particle size reduction and the poor wettability properties could also be improved. The dissolution rate was therefore significantly increased.     

Singularity of Crushing Behavior of Single Particles near Their Natural Period

Within grinding machines the load acting on the particles and the loading rate are widely distributed. According to studies on the breakage mechanism of brittle materials, the mechanical properties which relate to breakage vary with the loading rate. In order to elucidate the grinding mechanism within the grinding machines, it is necessary to obtain the relationships between these properties and loading rate. In this study, the variation of strength, fracture energy, new surface area produced by fracture and fracture energy with the loading rate (ranging from 10^?1 to 10⁹ N/s) was investigated by means of compression tests on a large number of spherical specimens. As a result, a singularity of crushing behavior was observed under an impact loading corresponding to a duration of time of loading the same as the natural period of the spherical specimen. The crushing efficiency is especially at its maximum.     

Characterization of biomaterials commonly used in dentistry for bone augmentation by X‐ray and electron techniques

Hydroxyapatite (HA), beta‐tricalcium phosphate and bioactive glasses are commonly used as reabsorbable biomaterials, mainly in orthopaedics and dentistry. The performance of each material depends on many factors, in particular, on their chemical and phase composition, microstructure, granule size and pore volume. For this reason, it is important to have a full characterization that allows correlating these properties with the material biological behaviour. In this work, three commercial samples of materials currently used in dentistry as bone substitutes were characterized. Granules corresponding to bovine and synthetic HA and bioactive glass 45S5 type were studied by scanning electron microscopy, conventional and synchrotron radiation X‐ray diffraction and X‐ray fluorescence. The specific surface area was also obtained by the Brunauer, Emmett and Teller method. We observed that Ca/P molar ratios for both HAs are higher than the value corresponding to the stoichiometric HA. The coherent domain obtained for the bovine HA is larger along the c axis crystal direction, and it is around 15 times lower than the value corresponding to the synthetic HA. The specific surface area for the bovine HA is one of the highest values reported in literature. Low amounts of crystalline CaO were observed only for the synthetic HA sample. Crystalline combeite and wollastonite were detected for the bioactive glass sample and quantified by using rutile as internal standard. The relation between the physico‐chemical characterization performed in this work and the potential biological response of the materials is discussed in terms of the information available in literature. Copyright © 2016 John Wiley & Sons, Ltd.     

Rheological Properties,Morphology, and Thermal Performance of E‐MA‐GMA/PC Blend

Blends of ethylene–methyl acrylate–glycidyl methacrylate terpolymer (E‐MA‐GMA, a random terpolymer) and polycarbonate (PC) were prepared in a Haake torque rheometer and the rheological properties, phase morphology, and thermal behavior were investigated. The graft reactions of PC terminal hydroxyl groups with the epoxy groups of E‐MA‐GMA and the in situ formation of the E‐MA‐GMA‐g‐PC copolymers at the interface were illustrated by the improved mixing torque and melt viscosity in E‐MA‐GMA/PC blends. Typical variation and significant deformation of the dispersed phase was observed in E‐MA‐GMA/PC blends with different composition, where PC was the matrix. With the E‐MA‐GMA content increasing, a complex co‐continuous phase structure with some dispersed E‐MA‐GMA particles wrapped in the continuous PC phase was present, indicating strengthened interfacial adhesion. When the E‐MA‐GMA content was higher than the PC component, fibrous structure of the dispersed PC phase in the E‐MA‐GMA matrix was caused by shear flow and interfacial interaction. DSC studies showed that the melting point of E‐MA‐GMA shifted to lower temperature with the increase of PC content, indicating that the enhanced interaction and graft structure hindered the process of crystallization and crystal growth.     

胶体金核壳型沙丁胺醇分子印迹聚合物的光谱特征分析

为了解决饲料和动物产品中沙丁胺醇残留现场快速检测的难题,开发以分子印迹技术为基础的快速检测沙丁胺醇的新方法,使用沙丁胺醇做为模板分子,甲基丙烯酸(methacrylic acid, MA)作为功能单体,以本体聚合法为基础合成常规SAL分子印迹聚合物（molecularly imprinted polymer,MIPs）和非分子印迹聚合物（non imprinted polymer NIPs）。在此基础上,以胶体金粒子为引发核,制备出新型的核壳型沙丁胺醇MIPs。应用紫外吸收光谱(UV spectra)、傅里叶红外光谱(IR spectra)和拉曼光谱（Raman spectru）、扫描电镜（scanning electron microscopy,SEM）等技术手段获得两种印迹物及各种相关化合物的光谱图、电镜图等表征图像。由实验结果可知,SAL和MA上的羧基形成稳定又容易洗脱的1∶1型氢键配合物,化学结合常数K=-0.245×106 L2·mol-2。与MA的—COOH中氢原子形成氢键的可能结合位点是SALCO中的氧原子。MIPs与MA中—OH的吸收峰比较可知,前者明显红移; 证明SAL作为模板分子与MA之间发生特定结合。未洗脱MIPs的CO的伸缩振动产生的吸收峰红移; 即能量损失明显,可知MA中—COOH的氢原子如果要生成氢键,可能的结合位点就是SAL分子内CO中的氧原子。MIPs和NIPs中CC, CO, —OH等吸收明显的官能团峰型大致相同。将MIPs洗脱掉作为模板分子的SAL后,留下了含有特殊且确定结构官能团化学及空间构成均与SAL高度匹配的空穴, 可与待测液中的目标检测分子SAL发生特异性识别和专一结合作用。而胶体金核壳型MIPs与常规MIPs相比,除具有以上相同特点外,其表面更加松散,表面孔穴明显增多。由此增加了吸附目标分子的有效面积,具有更优良的吸附性能。这两种印迹物的合成及光谱特征分析为建立基于分子印迹技术的快速检测SAL新方法奠定了理论和实践基础。     

In vitro effects of cisplatin-functionalized silica nanoparticles on chondrocytes

In this study, we evaluated the combined effect of a known toxic molecule, cisplatin, in combination with relatively nontoxic nanoparticles, amorphous fumed silica, on chondrocyte cells. Cisplatin was attached to silica nanoparticles using aminopropyltriethoxy silane as a linker molecule, and characterized in terms of size, shape, specific surface area, as well as the dissolution of cisplatin from the silica surface. The primary particle diameter of the as-received silica nanoparticles ranged from 7.1 to 61 nm, estimated from measurements of specific surface area, and the primary particles were aggregated. The effects of cisplatin-functionalized silica particles with different specific surface areas (41, 85, 202, 237, and 297 m²/g) were compared in vitro on chondrocytes, the parenchymal cell of hyaline cartilage. The results show that adverse effects on cell function, as evidenced by reduced metabolic activity measured by the MTT assay and increased membrane permeability observed using the Live/Dead stain, can be correlated with specific surface area of the silica. Cisplatin-functionalized silica nanoparticles with the highest specific surface area incited the greatest response, which was almost equivalent to that induced by free cisplatin. This result suggests the importance of particle specific surface area in interactions between cells and surface-functionalized nanomaterials.     

Characterization of scraps produced by the industrial laser cutting of steels

We have studied some properties relevant for technological applications of the debris produced by industrial laser cutting of steels. The investigated material is made up of spheroidal particles, hollow and solid, which get oxidized over the cutting process, and that we have reduced afterwards in a H₂ atmosphere. The samples, before and after the reduction, were characterized by X-ray diffraction, scanning electron microscopy, specific surface area and Mössbauer spectroscopy. We have found that, after the reduction treatment, the shape remains unchanged but that the chemical composition and the physical properties of the external and internal surface structures are modified. In particular, the specific surface area of the material increased by one order of magnitude.     

Physical and Chemical Characterization of Therapeutic Iron Containing Materials: A Study of Several Superparamagnetic Drug Formulations with the β-FeOOH or Ferrihydrite Structure

The effectiveness of therapeutically used iron compounds is related to their physical and chemical properties. Four different iron compounds used in oral, intravenous, and intramuscular therapy have been examined by X-ray powder diffraction, iron-57 Mössbauer spectroscopy, transmission electron microscopy, BET surface area measurement, potentiometric titration and studied through dissolution kinetics determinations using acid, reducing and chelating agents. All compounds are nanosized with particle diameters, as determined by X-ray diffraction, ranging from 1 to 4.1 nm. The superparamagnetic blocking temperatures, as determined by Mössbauer spectroscopy, indicate that the relative diameters of the aggregates range from 2.5 to 4.1 nm. Three of the iron compounds have an akaganeite-like structure, whereas one has a ferrihydrite-like structure. As powders the particles form large and dense aggregates which have a very low surface area on the order of 1 m²?g^?1. There is evidence, however, that in a colloidal solution the surface area is increased by two to three orders of magnitude, presumably as a result of the break up of the aggregates. Iron release kinetics by acid, chelating and reducing agents reflect the high surface area, the size and crystallinity of the particles, and the presence of the protective carbohydrate layer coating the iron compound. Within a physiologically relevant time period, the iron release produced by acid or large chelating ligands is small. In contrast, iron is rapidly mobilized by small organic chelating agents, such as oxalate, or by chelate-forming reductants, such as thioglycolate.

     

Laser surface treatment of regenerated cellulose fiber

Effects of the excimer laser irradiation on regenerated cellulose fibers were investigated. The surface structure change was remarkable only when the ArF laser was applied. Small pores and fibrils were observed on the fiber surface at the high fluence irradiation. In some cases, several cracks were observed inside the fiber. The fiber structure change was strongly dependent on fluence and number of pulses. XPS analysis indicated an increase of carbonyl groups and removal of CO and CO₂ on the fiber surface. Concerning the fiber properties, the tensile strength lowered, and the moisture content was improved a little. Those property changes could be explained by the breakage of intermolecular hydrogen bonding and that of the main chain of the cellulose molecule. Increase of specific surface area and chemical structure change suggest that irradiated fiber can be applied as a component for soft composite materials.     

Quantum mechanics simulation and experimental study of adhesive interaction and aggregation of carbon-silicate nanoparticles—reinforcing fillers of polymer composites

Nanoparticles are widely used as polymer composite-reinforcing additives—fillers. Understanding the interaction mechanisms and regularities responsible for nanoparticle aggregation is of great significance for elucidating the nature of reinforcing of polymer composites. The paper reports on quantum mechanics calculations and full-scale experimental study of adhesive interaction of carbon and silicate adsorption complexes (nanomodels of active filler particles of polymer composites). The quantum mechanics approach allowed describing the adhesive properties of particle aggregates reasoning from nanoscopic structure of their surface. The quantum mechanics data were checked for adequacy on schungite—a natural mineral containing carbon and silicate. Schungite microparticles were milled to nanosizes by colloidal grinding in various disperse liquid media (alcohol, acetone, water) and the structure and properties of aggregated schungite micro- and nanoparticles were studied; fractal analysis of their surface was performed. It is found that smaller aggregates of silicate and carbon particles with higher surface fractal dimension are formed in colloidal grinding with small molecular sizes of disperse media (in our case, ethanol or methanol) and this agrees with the data predicted by quantum mechanics calculations.     

Controllable synthesis, characterization, and magnetic properties of nanoscale zerovalent iron with specific high Brunauer–Emmett–Teller surface area

This article reports a novel approach for the controllable synthesis of nanoscale zerovalent iron (NZVI) particles with specific high Brunauer–Emmett–Teller (BET) surface areas. Borohydride reduction is a primary and effective liquid phase reduction method for the synthesis of zerovalent iron nanoparticles. However, previous methods for synthesizing NZVI did not suggest a standard technique for controlling the size of particles during the synthesis process; in addition, previous literature generally reported that NZVI had a BET surface area of <37 m²/g. In this communication, a novel approach for the controllable synthesis of NZVI particles with specific high BET surface areas is presented. As a result, the BET surface areas of the NZVI particles synthesized increased to 47.49 and 62.48 m²/g, and the particle sizes decreased to 5–40 and 3–30 nm. Additionally, the physical and chemical properties of the synthesized NZVI particles were investigated by a series of characterizations, and magnetic analysis indicated that the synthesized NZVI particles had super-paramagnetic properties.     

On‐line Determination of Particle Size Distributions in Flowing Dispersions

Emulsions are of great importance to industry. They are involved in many engineering operations, including chemical reactions, extraction, emulsification and suspension polymerization, etc. However, an important problem for these processes is how to control the size distribution of the dispersed phase. Indeed, off‐line analysis of the emulsion may generate uncertainties due to sampling and dilution of the product, which are likely to change the dispersion state and physico‐chemical properties. In this work, an on‐line optical method is proposed to characterize dispersed media in real flowing conditions. This method is based on the time‐analysis of back‐scattered light fluctuations. The present paper deals with the development of this method and its application to dispersions of alumina in water. The results obtained with the on‐line optical method are compared with those acquired by classical laser light scattering and microscopy.     

Surface spin disorder and spin-glass-like behaviour in manganese-substituted cobalt ferrite nanoparticles

Due to the increasing use of silver nanoparticles (AgNPs) in consumer products, it is essential to understand how variables, such as light exposure, may change the physical and chemical characteristics of AgNP suspensions. To this end, the effect of 300?nm ultraviolet (UV) light on (20, 40, 60 and 80)?nm citrate-capped AgNP suspensions has been investigated. As a consequence of irradiation, the initial yellow hue of the AgNP suspensions is transformed towards a near colorless solution due to the loss of the surface plasmon resonance (SPR) absorbance. The decrease in SPR absorbance followed a first-order decay process for all particle sizes with a rate constant that increased linearly with the AgNP specific surface area and non-linearly with light intensity. The rate of loss of the SPR absorbance decreased with increasing citrate concentration, suggesting a surface-mediated transformation. Absorbance, atomic force microscopy, and dynamic light scattering results all indicated that AgNP photolysis was accompanied by a diameter decrease and occasional aggregation. Furthermore, in situ transmission electron microscopy imaging using a specialized liquid cell also showed a decrease in the particle size and the formation of a core?Cshell structure in UV-exposed AgNPs. X-ray photoelectron spectroscopy analysis suggested that this shell consisted of oxidized silver. The SPR in UV-exposed AgNP suspensions could be regenerated by addition of a strong reducing agent (NaBH₄), supporting the idea that oxidized silver is present after photolysis. Evidence for UV-enhanced dissolution and the production of silver ions was obtained with the Donnan membrane technique. This study reveals that the physico-chemical properties of aqueous AgNP suspensions will change significantly upon exposure to UV light, with implications for environmental health and safety risk assessments.     

Thermoresponsive Gold Polymer Nanohybrids with a Tunable Cross‐Linked MEO2MA Polymer Shell

Gold nanoparticles (AuNPs) are functionalized with a thermoresponsive polymer shell of a cross‐linked poly(2‐(2‐methoxyethoxy)ethyl methacrylate) (P(MEO₂MA)). To provide a covalent attachment of the polymer to the NP surface, AuNPs are first modified using butanoic acid to develop the encapsulation with the biocompatible thermoresponsive polymer formed by free‐radical precipitation polymerization. Both the MEO₂MA concentration and the shell cross‐linking density can be varied and, in turn, the thickness and the shells' free volume can be fine‐tuned. By downscaling the size of the polymeric shell, the lower critical solution temperature (LCST) is decreased. The LCST in the nanohybrids changes from 19.1 to 25.6 °C when increasing the MEO₂MA content; it reaches almost 26 °C for P(MEO₂MA) (bulk). The maximum decrease in the volume of the nanohybrids is around 40%, resulting in a modification of the light scattering properties of the system and causing a change in the turbidity of the gel network. The sizes of the nanohybrids are characterized using both transmission electron microscopy and dynamic light scattering measurements. Optical properties of the colloidal systems are determined using the derived count rate measurements as an alternative to absorbance or transmittance measurements, confirming the colloidal stability of the nanohybrid systems.     

Sulfur Immobilized in Hierarchically Porous Structured Carbon as Cathodes for Lithium–Sulfur Battery with Improved Electrochemical Performance

In order to overcome the main obstacles for lithium–sulfur batteries, such as poor conductivity of sulfur, polysulfide intermediate dissolution, and large volume change generated during the cycle process, a hard‐template route is developed to synthesize large‐surface area carbon with abundant micropores and mesopores to immobilize sulfur species. The microstructures of the C/S hybrids are investigated using field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherms, and electrochemical impedance spectroscopy techniques. The large surface and porous structure can effectively alleviate large strain due to the lithiation/delithiation process. More importantly, the micropores can effectively confine small molecules of sulfur in the form of S_2–4, avoiding loss of active S species and dissolution of high‐order lithium polysulfides. The porous C/S hybrids show significantly enhanced electrochemical performance with good cycling stability, high specific capacity, and rate capability. The C/S‐39 hybrid with an optimal content of 39 wt% S shows a reversible capacity of 780 mA h g^?1 after 100 cycles at the current density of 100 mA g^?1. Even at a current density of 5 A g^?1, the reversible capacity of C/S‐39 can still maintain at 420 mA h g^?1 after 60 cycles. This strategy offers a new way for solving long‐term reversibility obstacle and designing new cathode electrode architectures.     

Calcination of Rod-like Hydroxyapatite Nanocrystals with an Anti-sintering Agent Surrounding the Crystals

Sintering-free nanocrystals of calcined hydroxyapatite (HAp) having a rod-like morphology were fabricated by calcination at 800°C for 1 h with an anti-sintering agent surrounding original HAp particles and the agent was subsequently removed after calcination. The original HAp particles having a rod-like morphology with a size ranging from 30 to 80 nm (short axis) and 300 to 500 nm (long axis) were prepared by wet chemical process, and poly(acrylic acid, calcium salt) (PAA-Ca) was used as the anti-sintering agent. In the case of calcination without additives, the mean size of HAp crystals dispersed in an ethanol medium increased by about 4 times and the specific surface area of the crystals exhibited a 25% decrease compared to those of the original HAp particles because of calcination-induced sintering among the crystals. On the other hand, the HAp crystals calcined with the anti-sintering agent, PAA-Ca, could be dispersed in an ethanol medium at the same size as the original particles, and they preserved the specific surface area after calcination. These results indicate that PAA-Ca and/or its thermally decomposed product, CaO, surrounded the HAp particles and protected them against calcination-induced sintering during calcination. The HAp crystals calcined with PAA-Ca showed high crystallinity, and no other calcium phosphate phases could be detected after washing with water.     

Sonochemical fabrication of gradient antibacterial materials based on Cu-Zn alloy

At present research, we highlight ultrasonic treatment as a new way to create materials with a gradient change of chemical or physical properties. We demonstrate the possibility to fabricate novel materials with biocide activity based on simple and cheap Cu-Zn alloy. In this research, we propose a green preparative technique for the sonication of an alloy in an alkali solution. The method leads to a significant visual change and differentiation of particles into three different fractions. Due to the chemical micro gradients in media near the solid surface under intensive sonication, fast formation of specific functional groups occurs on the particles’ surface. The particles were studied X-ray diffraction analysis (XRD) analysis, the field-emission scanning electron microscope (SEM) as well as electron backscatter diffraction (EBSD) mode, X-ray Photoelectron Spectroscopy (XPS), the differential pulse anodic stripping voltammetry (DPASV) technique. A strong correlation of both methods proves a redistribution of copper ions from Fraction I to Fraction III that influence for the antibacterial properties of the prepared material. The different biocidal activity was demonstrated for each separated Fraction that could be related to their different phase content and ability to release the different types of ions.