Characterization of Calcium Titanate–Magnesium Titanate Eutectic by Scanning Microwave Microscopy

Microstructure and dielectric properties in a CaTiO₃ (CT)–MgTiO₃ (MT) diffusion couple were studied by scanning electron microscopy (SEM) and near-field scanning microwave microscopy (SMM). Complex microstructures containing Mg₂TiO₄ (M2T) and MgTi₂O₅ (MT2) phases as well as eutectic structures of CT–MT and MT2–CT developed during cooling from the melt. Variations in the local dielectric properties observed in SMM images are correlated with the microstructures characterized by SEM/EDS. The SMM characterization clearly distinguished low-dielectric-constant MT and high-dielectric-constant CT phases. The M2T, MT, and MT2 phases have similar dielectric properties, and were more difficult to distinguish in the SMM. The phase development during melting and solidification, and SMM imaging limitations are discussed.     

Expression of the MT1 Melatonin Receptor in Ovarian Cancer Cells

Ovarian cancer (OC) is the leading cause of death among women with genital tract disorders. Melatonin exhibits oncostatic properties which it may effect through binding to its membrane receptor, MT1. The aim of this study was to determine the expression of MT1 in OC cells and to correlate this with clinical and pathological data. Immunohistochemistry was performed on 84 cases of OC. Normal ovarian epithelial (IOSE 364) and OC (SK-OV-3, OVCAR-3) cell lines were used to examine the MT1 expression at protein level using the western blot and immunofluorescence technique. The expression of MT1 was observed as cytoplasmic-membrane (MT1_CM) and membrane (MT1_M) reactions. A positive correlation between MT1_CM and MT1_M was found in all the studied cases. There were no significant differences between the expression of MT1_CM, MT1_M, and histological type, staging, grading, presence of residual disease, or overall survival time. Immunofluorescence showed both MT1_M and MT1_CM expression in all the tested cell lines. Western blot illustrated the highest protein level of MT1 in IOSE 364 and the lowest in the OVCAR-3. The results indicate the limited prognostic significance of MT1 in OC cells.     

Construction of hybrid nanocomposites containing Pt nanoparticles and poly(3-methylthiophene) nanorods at a glassy carbon electrode: Characterization, electrochemistry, and electrocatalysis

Hybrid nanocomposites containing Pt nanoparticles (nano-Pt) and poly(3-methylthiophene) (P3MT) nanorods at glassy carbon surfaces have been successfully prepared by use of an in situ cyclic voltammetry (CV) method. Field emission scanning electron microscope (FE-SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltagrams were used to characterize the properties of these nanocomposites. SEM images showed that nano-Pt were located on the surface of P3MT nanorods and that they formed a three-dimensional (3D) porous nanostructure. EIS and CV results demonstrated that these hybrid nanocomposites had good conductivities, and could accelerate the electron-transfer rates of redox ions. From the results of electrochemical oxidation of methanol and nitrite, we observed that this nanocomposite-modified electrode exhibited excellent electrocatalytic activity, which might be useful in biosensors and/or fuel cells.     

Imparting conductivity and chromic behavior on polyester fibers by means of poly(3‐methylthiophene) nanocoating

Poly(3‐methylthiophene) (P3MT)‐coated polyester fabric is a conductive textile with specific electrical and optical properties; for instance, color change under external stimulus (chromic behavior) was successfully prepared by chemical polymerization with continuous, speed stirring technique. To investigate the striking effect of some variable conditions of polymerization process, the effect of reaction time, temperature, and oxidant concentration on conductivity of the P3MT‐coated fabric was studied. Scanning electron microscopy confirmed that the surface of fabric has entirely been coated with P3MT particles. The further characterizations were investigated using Fourier transform infrared spectroscopy to provide evidence of forming particles onto the fabric, UV–vis absorption spectroscopy, electrical surface resistivity, and pressure dependence visible reflectance spectrophotometer measurements and X‐ray diffraction analysis. The blue shift in wavelength of maximum absorption of about 95 nm to a longer wavelength from that observed in the reflectance spectra of coated polyester fabric; under high‐pressure P3MT‐coated polyester fabric demonstrated piezochromism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Sulfonated Styrene-(ethylene-co-butylene)-styrene/Montmorillonite Clay Nanocomposites: Synthesis, Morphology, and Properties

Sulfonated styrene-(ethylene-butylene)-styrene triblock copolymer (SSEBS) was synthesized by reaction of acetyl sulfate with SEBS. SSESB-clay nanocomposites were then prepared from hydrophilic Na-montmorillonite (MT) and organically (quaternary amine) modified hydrophobic nanoclay (OMT) at very low loading. SEBS did not show improvement in properties with MT-based nanocomposites. On sulfonation (3 and 6 weight%) of SEBS, hydrophilic MT clay-based nanocomposites exhibited better mechanical, dynamic mechanical, and thermal properties, and also controlled water–methanol mixture uptake and permeation and AC resistance. Microstructure determined by X-ray diffraction, atomic force microscopy, and transmission electron microscopy due to better dispersion of MT nanoclay particles and interaction of MT with SSEBS matrix was responsible for this effect. The resulting nanocomposites have potential as proton transfer membranes for Fuel Cell applications.     

Electroactive polymers for the detection of morphine

The interaction between morphine (MO), a very potent analgesic psychoactive drug, and five electroactive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-methylthiophene) (P3MT), polypyrrole (PPy), poly(N-methylpyrrole (PNMPy) and poly[N-(2-cyanoethyl)pyrrole] (PNCPy), has been examined using theoretical calculations on model complexes and voltammetric measures considering different pHs and incubation times. Quantum mechanical calculations in model polymers predict that the strength of the binding between the different polymers and morphine increases as follows: PEDOT < PNMPy < Py < < P3MT ≈ PNCPy. The most relevant characteristic of P3MT is its ability to interact with morphine exclusively through non-directional interactions. On the other hand, the variations of the electroactivity and the anodic current at the reversal potential evidence that the voltammetric response towards the presence of MO is considerably higher for P3MT and PNCPy than that for the other polymers at both acid (P3MT > PNMPy) and neutral (P3MT ≈ PNCPy) pHs. Energy decomposition analyses of the interaction of MO with different model polymers indicate that the stronger affinity of MO for P3MT and PNCPy as compared to PEDOT, PNMPy, and PPy is due to more favorable orbital interactions. These more stabilizing orbital interactions are the result of the larger charge transfer from MO to P3MT and PNCPy model polymers that takes place because of the higher stability of the single occupied molecular orbital (SOMO) of these model polymers. Therefore, to design polymers with a large capacity to detect MO we suggest looking at polymers with high electron affinity.     

Ba0.6Sr0.4TiO3-Mg2TiO4复合陶瓷材料的介电可调性及微波特性

采用常规的陶瓷工艺方法制备了Ba0.6Sr0.4TiO3-Mg2TiO4(BST-MT)复合陶瓷材料,并对其相结构、介电以及可调性和微波特性进行了研究.X射线衍射和介电温度特性测试结果表明,BST-MT复合陶瓷具有BST和MT两相结构,非铁电相MT的增加降低了其铁电性,使其介电常数和介电损耗减小.介电偏压和微波性能测试结果表明,BST-MT复合材料仍能保持较高的可调性,且微波性能得到了明显改善.样品30%BST-70%MT(质量分数)在10 kHz下的介电常数为78,介电损耗为0.000 6,在外加3 kV/mm偏置电场作用下,可调性达到25%,在3.714 GHz频率下的介电损耗为0.0145.     

Effect of stabilizer type on the mechanical properties of rigid poly(vinyl chloride). I

The effect of stabilizers on the mechanical properties of UPVC and how these are affected by different formulations has been studied. Three stabilizers, tin mercaptide MT, lead system Pb, and Ba/Cd/Zn complex BCZ, were used. A high -intensity blender was used for dry blend compounding, and the blend was injection -molded on a Kuasy single Screw injection molding machine. A two -cavity mold was made for forming the specimens. The specimens were tested for their impact strength, fracture toughness, tensile strength, and flexural strength. Increasing MT stabilizer was shown to increase the tensile strength and to decrease fracture toughness, impact strength, and ductility; this was attributed to antiplasticization. Increasing the Pb stabilizer conferred ductility and improved fracture toughness and impact strength. It is concluded that stabilizers have a marked effect on the mechanical behavior of rigid PVC.     

Individual Variations in Inorganic Arsenic Metabolism Associated with AS3MT Genetic Polymorphisms

Individual variations in inorganic arsenic metabolism may influence the toxic effects. Arsenic (+3 oxidation state) methyltransferase (AS3MT) that can catalyze the transfer of a methyl group from S-adenosyl-l-methionine (AdoMet) to trivalent arsenical, may play a role in arsenic metabolism in humans. Since the genetic polymorphisms of AS3MT gene may be associated with the susceptibility to inorganic arsenic toxicity, relationships of several single nucleotide polymorphisms (SNPs) in AS3MT with inorganic arsenic metabolism have been investigated. Here, we summarize our recent findings and other previous studies on the inorganic arsenic metabolism and AS3MT genetic polymorphisms in humans. Results of genotype dependent differences in arsenic metabolism for most of SNPs in AS3MT were Inconsistent throughout the studies. Nevertheless, two SNPs, AS3MT 12390 (rs3740393) and 14458 (rs11191439) were consistently related to arsenic methylation regardless of the populations examined for the analysis. Thus, these SNPs may be useful indicators to predict the arsenic metabolism via methylation pathways.     

In vitro cyclic fatigue and hydrothermal aging lifetime assessment of yttria-stabilized zirconia dental ceramics

The in vitro lifetime assessment of dental zirconia has been the focus of researchers. This work mainly studied the cyclic fatigue lifetime in saliva and aging lifetime of three commercial zirconia dental materials: two kinds of 3 mol%-yttria stabilized zirconia ST(super-translucence) and MT(medium-translucence), in which MT contains a small amount of alumina; a 5 mol%-yttria stabilized zirconia TT(tooth-translucency). ST and MT materials have higher initial mechanical strength (flexural strength) and initial crack propagation threshold than TT materials, thus they have longer cycle fatigue lifetime, but TT has best aging resistance(no aging) in existing aging procedures. MT has a higher initial mechanical strength and better aging resistance than ST samples due to the influence of alumina at grain boundary, but has lower strength reliability. Finally the service lifetime of the three materials was evaluated, and some guidance for their use is provided.     

Dielectric Properties and Leakage Current Characteristics of Sol-Gel Derived (Ba0.5Sr0.5)TiO3:MgTiO3 Thin Film Composites

(Ba_1-xSr_x)TiO₃ (BST) is a suitable material for microelectronic device applications due to its high response of the dielectric permittivity to an applied electric field. However, the large dielectric constants found in this system limit its usefulness at microwave frequencies. In our recent studies sol-gel prepared Ba_0.5Sr_0.5TiO₃:MgO heterostructured thin films have shown an increase in the figure of merit (tunability/loss) compared to pure Ba_0.5Sr_0.5TiO₃ films, but the leakage characteristics of these films did not improve significantly. Moreover, due to the hygroscopic nature of MgO, the BST:MgO heterostructured films may suffer with longer period of time instability. In this paper we used the low loss and non-hygroscopic MgTiO₃ for the fabrication of the Ba_0.5Sr_0.5TiO₃:MgTiO₃ (BST50:MT) heterostructured thin films by sol-gel technique and studied the effects of MgTiO₃ layers on the structural, physical, dielectric properties, and leakage current behavior of the BST:MT films. The X-ray studies indicated that both MT and Ba_0.5Sr_0.5TiO₃ are highly oriented and remain as two distinct individual entities in the composite films and a considerable reduction in the dielectric loss and leakage currents has been observed. High frequency phase shifter studies (at low voltage) suggest that these films are suitable for the tunable microwave device applications.     

Optimization of new voltammetric method for the determination of metallothionein

Electrochemical determination of metallothioneins (MTs) is widely used for environmental studies. In this paper, a new procedure for the quantification of MT by square wave cathodic stripping voltammetry has been developed and optimized. The determination is based on the complexation of cisplatin and MT and the subsequent reduction of the complexes at the electrode. In order to achieve highest sensitivity and resolution of the peak, an optimization of the experimental parameters has been carried out using experimental design methodology (response surface). Seven chemical and physical parameters namely pH, cisplatin concentration, buffer concentration, deposition potential, square wave frequency, amplitude of the pulse and step potential have been optimized. Method characterization has been performed, leading to a detection limit of 6×10⁻¹² mol l⁻¹. This sensitivity is comparable to that of immunoassay, inducing that this procedure may also be used for MT quantification in tissue or serum.     

Experimental study on the optimum performance of an adiabatic MT reactor

The performance of an adiabatic MT reactor has been studied under various experimental conditions, using the reaction between hydrogen peroxide and sodium thiosulphate. Following the M-section, consisting of a CSTR, the T-section was made up of a large number of small stirred tanks in series. The same general condition for optimizing the MT model, that the reaction rate in the M-section be a maximum, is shown to apply when maximizing the conversion for a given residence time as it was shown previously to apply when minimizing the residence time for a given conversion. Very good agreement is shown between theoretical and experimental results, confirming the superior results often obtained with an MT combination as compared with those given by a stirred tank or a tubular reactor under similar conditions. Bi-stable steady states of conversion have been achieved and their effect shown on the performance of the combined reactor.     

Development of a stochastic individual path (SIP) model for predicting the tracheobronchial deposition of pharmaceutical aerosols: Effects of transient inhalation and sampling the airways

While a number of studies have considered the dynamics of ambient or environmental particles in the respiratory tract, far fewer have evaluated the transport and deposition of pharmaceutical aerosols from inhalers in the mouth-throat (MT) and tracheobronchial (TB) airways. The objective of this study was to develop a new stochastic individual path (SIP) modeling approach for simulating the MT and TB deposition of a pharmaceutical aerosol from a dry powder inhaler and to evaluate the effects of transient vs. steady state conditions and sampling of the airways. In the SIP approach, representative models of the MT and upper TB geometries are considered through the third respiratory bifurcation (B3; approximately lobar bronchi). Stochastic individual paths are then evaluated extending from B4 to the terminal bronchioles (B15) in which one branch of each bifurcation is continued and one is not. Three SIP geometries were considered extending into the lower right lung lobe through the end of the conducting airways. A commonly prescribed dry powder inhaler (DPI) was connected to the MT geometry and the deposition of drug mass from a realistic polydisperse pharmaceutical aerosol was evaluated. Predictions of deposited drug mass in the MT and upper TB geometries were found to be in good agreement with concurrent experimental results. Transient inhalation was shown to influence the deposition of particles in the MT and upper TB airways through B3, where the Womersley number is greater than 1. In contrast, transient conditions were found to have little influence on deposition in the TB region starting with B4, where steady state simulations provided a good representation of total, regional, bifurcation-averaged, and localized deposition. Furthermore, a single SIP model was shown to characterize both regional and highly localized deposition within a lung lobe assuming mean airway dimensions. The resulting SIP model provides a highly efficient method to simulate the regional and local deposition of pharmaceutical aerosols throughout the conducting airways. In comparison with performing fully transient simulations of all branches in the regions considered, the SIP modeling approach reduces computational effort by a factor of approximately 3×10⁵ while predicting regional and local deposition values to within approximately 5%.     

Preparation and electromagnetic properties of the BaFe12O19/multiwall carbon nanotubes/poly(3‐methyl‐thiophene) composites

The BaFe₁₂O₁₉/multiwall carbon nanotubes/poly(3‐methyl‐thiophene) (BaFe₁₂O₁₉/MCNTs/P(3MT)) composites were synthesized through an in situ chemical polymerization of 3‐methyl‐thiophene (3MT) in the presence of BaFe₁₂O₁₉/MCNTs composite powders. The BaFe₁₂O₁₉/MCNTs/P(3MT) composites were characterized by the fourier transform infrared spectrometry (FTIR) and X‐ray diffraction (XRD). The morphologies of the composites were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electric conductive properties were tested by a four‐probe conductivity tester and the magnetic properties were measured by vibrating sample magnetometer (VSM). The electromagnetic performance tests showed that when the mass ratio of BaFe₁₂O₁₉ to MCNTs was 0.4, and the BaFe₁₂O₁₉/MCNTs to P(3MT) was 0.15, the conductivity, saturation magnetization (M_s) and residual magnetization (M_r) of the BaFe₁₂O₁₉/MCNTs/P(3MT) composites achieved 166.740 S/m, 29.884 emu/g, and 17.581 emu/g, respectively. POLYM. COMPOS., 34:1801–1808, 2013. © 2013 Society of Plastics Engineers     

Reactivities towards the benzoyloxy radical of monomers with beta-methyl groups

Summary Polymers of methyl methacrylate have been prepared at 60°C with benzoyl peroxide as initiator in the presence of methyl tiglate (MT), methyl crotonate (MC) or crotononitrile (CNL); they have been examined for end-groups derived from the initiator. The introduction of beta-methyl groups into methyl methacrylate, methyl acrylate and acrylonitrile (to give MT, MC and CNL respectively) increases reactivity towards the benzoyloxy radical. The effects can be explained in terms of the electron-repelling methyl groups activating the double bonds for reaction with the electrophilic benzoyloxy radical.     

The Melatonergic System in Mood and Anxiety Disorders and the Role of Agomelatine: Implications for Clinical Practice

Melatonin exerts its actions through membrane MT1/MT2 melatonin receptors, which belong to the super family of G-protein-coupled receptors consisting of the typical seven transmembrane domains. MT1 and MT2 receptors are expressed in various tissues of the body either as single ones or together. A growing literature suggests that the melatonergic system may be involved in the pathophysiology of mood and anxiety disorders. In fact, some core symptoms of depression show disturbance of the circadian rhythm in their clinical expression, such as diurnal mood and other symptomatic variation, or are closely linked to circadian system functioning, such as sleep-wake cycle alterations. In addition, alterations have been described in the circadian rhythms of several biological markers in depressed patients. Therefore, there is interest in developing antidepressants that have a chronobiotic effect (i.e., treatment of circadian rhythm disorders). As melatonin produces chronobiotic effects, efforts have been aimed at developing agomelatine, an antidepressant with melatonin agonist activity. The present paper reviews the role of the melatonergic system in the pathophysiology of mood and anxiety disorders and the clinical characteristics of agomelatine. Implications of agomelatine in “real world” clinical practice will be also discussed.     

阻燃、抗静电PA6柱靴的开发与应用

以柱靴为研究对象,探讨了工程塑料在煤矿井下应用的问题。研制的柱靴材料阻燃、抗静电性能达到MT113—85标准。用该材料制作的柱靴抗压实验合格,部分产品已经在煤矿井下试用。     

Effect of natural and organically modified montmorillonite clays on the properties of polydimethylsiloxane rubber

The effects of natural (MT) and organically modified (O‐MT) montmorillonite clays on the properties of polydimethylsiloxane (PDMS) rubber were evaluated. Rubber composites with different clay contents were prepared by a compounding procedure in an open two‐roll mill, which was followed by a compression‐molding step in which the PDMS matrix was peroxide crosslinked. The clay rubber composites were characterized by swelling measurements in toluene, thermogravimetric analyses, X‐ray diffraction, scanning electron microscopy, and tensile tests. The introduction of MT restricted the solvent swelling and increased the crosslinking density of the rubber, which indicated the formation of a covalent filler–matrix interface. The enhanced interaction between MT and PDMS reduced the aggregation size of MT particles in the MT composites and promoted an increase in the separation of the clay layers. When the rubber was filled with O‐MT, a higher solvent amount was incorporated in the material, and this trend increased with the clay content. Moreover, the low interaction between O‐MT and the PDMS chains resulted in larger clay aggregates in the O‐MT composites compared to those with MT. Despite the different interface natures, both clays enhanced thermal stability and acted as reinforcing fillers in relation to Young's modulus and tensile strength. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008