Effect of trisodium citrate on morphological,structural, and optical properties of fluorine-doped ZnO structures

In this work, we present the effect of trisodium citrate (TSC) addition via a hydrothermal method on the morphological, compositional, structural, and optical changes of fluorine-doped zinc oxide (FZO) on silicon substrates. Field emission scanning electron microscopy revealed vertically aligned nanorods for FZO and pebble and block-like microstructures of different sizes upon TSC addition. X-ray diffraction analysis revealed a hexagonal structure for all the samples. Upon addition of TSC, the sample growth along the c-axis was inhibited strongly and the growth along the a-axis was developed. The crystallite size increased from 28.73 nm to 30.38 nm upon addition of TSC. The oxygen deficiency and, the presence of zinc, oxygen, fluorine, and sodium in the studied samples were confirmed by energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy (XPS). Ultraviolet (UV)-visible analysis revealed the optical energy band gap increment from 3.204 eV to 3.241 eV with TSC addition. Photoluminescence (PL) analysis revealed a significant improvement in the intensity ratio of the near band emission to deep level emission from 5.44 to 12.59 upon TSC addition, indicating crystal quality improvement. Both UV–visible and PL analyses showed that the studied samples were blue-shifted upon TSC addition. The different morphologies with promising properties could be employed in different applications, eliminating the complexity and reducing cost in the fabrication of hybrid structures, and nano/microcomposites.     

Improving hardness and toughness of plasma sprayed Ti–Si–C nano-composite coatings by post Ar-annealing

Ti–Si–C (TSC) composite coatings were fabricated by plasma spraying using Ti/Si/graphite agglomerates as feedstock. Ar-annealing was carried out to reduce the intrinsic defects and increase the performance of the as-sprayed TSC coating. The effects of the annealing temperature (500–900 °C) on the microstructures and mechanical performances of the TSC coatings were investigated. All TSC coatings consisted of TiC, Ti₅Si₃ and MAX phase Ti₃SiC₂. With the increase in temperature (>700 °C), TiC became predominant, while the Ti₃SiC₂ phase content increased, which was accompanied by a decrease in Ti₅Si₃ content. The high -temperature annealing (>700 °C) led to a homogenous microstructure with a relatively low porosity and increased number of micro-cracks. Notably, the hardness and fracture toughness of the TSC coating were simultaneously increased after the annealing, from 1164 HV to 1.96 MPa m^1/2 to 1560 HV and 3.45 MPa m^1/2, respectively. The formation of nanoscale TiC and Ti₅Si₃ with a network distribution, uniform and dense microstructure, and toughening effects of Ti₃SiC₂ and micro-cracks provided the high mechanical performances of the TSC composite coatings.     

Study on the relaxation of polystyrene,ethylene–propylene diene monomer,and the blends of polystyrene with ethylene–propylene diene monomer by thermally stimulated current

A thermally stimulated current (TSC) was used to study the relaxation of polystyrene (PS), the ethylene–propylene diene monomer (EPDM), and the grafted copolymer of EPDM with styrene (EPDM-g-St). The effect of the measuring conditions on the relaxation of PS is discussed. Some relaxation parameters of PS, EPDM, and EPDM-g-St were calculated in two different ways. In addition, the TSC spectra of PS/EPDM and PS/EPDM-g-St showed that PS/EPDM was an immiscible system, but there existed a special interaction between the plastic phase and the rubber one in PS/EPDM-g-St blends. The compatibility of PS blends was evaluated in terms of their compositions. The results of inverse gas chromatography (IGC) agreed well with those of the TSC measurements. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1199–1204, 1998     

Immobilization of heavy metals in a contaminated soil using organic sludge char and other binders

The applicability of tannery (TSC) and dye sludge char (DSC) as a binder to immobilize heavy metals (Zn, Cu and Ni) in soil was investigated. The toxicity characteristic leaching procedure (TCLP) was used to estimate the immobilization efficiency for single-binders (TSC and DSC) and binary-binders (TSC or DSC combined with tripostassium phosphate (K₃PO₄) diammonium phosphate (DAP), lime or ladle slag). The immobilization efficiencies of Zn, Cu and Ni by TSC amendment were 84.2, 100.0 and 40.0%, respectively, which were higher than 28.5, 100.0 and 54.9% by DSC amendment for a binder dose of 0.80 g char/g soil. The binary-binder enhanced Zn immobilization to 56.3 and 97.2% at 0.6 g-DSC/0.06 g-Ca(OH)₂ and 0.4 g-TSC/0.08 g-Ca(OH)₂, respectively per 1 g dried soil. The immobilization efficiencies of heavy metals increased with aging for the DSC-binary binders, but not for TSC-binary binders.     

The Characterization of a Subependymal Giant Astrocytoma-Like Cell Line from Murine Astrocyte with mTORC1 Hyperactivation

Tuberous sclerosis complex (TSC) is a genetic disorder caused by inactivating mutations in TSC1 (hamartin) or TSC2 (tuberin), crucial negative regulators of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway. TSC affects multiple organs including the brain. The neurologic manifestation is characterized by cortical tubers, subependymal nodules (SEN), and subependymal giant cell astrocytoma (SEGA) in brain. SEGAs may result in hydrocephalus in TSC patients and mTORC1 inhibitors are the current recommended therapy for SEGA. Nevertheless, a major limitation in the research for SEGA is the lack of cell lines or animal models for mechanistic investigations and development of novel therapy. In this study, we generated TSC1-deficient neural cells from spontaneously immortalized mouse astrocytes in an attempt to mimic human SEGA. The TSC1-deficient cells exhibit mTORC1 hyperactivation and characteristics of transition from astrocytes to neural stem/progenitor cell phenotypes. Rapamycin efficiently decreased mTORC1 activity of these TSC1-deficient cells in vitro. In vivo, TSC1-deficient cells could form SEGA-like tumors and Rapamycin treatment decreased tumor growth. Collectively, our study generates a novel SEGA-like cell line that is invaluable for studying mTORC1-driven molecular and pathological alterations in neurologic tissue. These SEGA-like cells also provide opportunities for the development of novel therapeutic strategy for TSC patients with SEGA.     

Structure of waterborne coatings by electrochemical impedance spectroscopy and a thermostimulated current method: influence of fillers

Electrochemical impedance spectroscopy (EIS) was coupled with a thermostimulated current (TSC) method to investigate the effect of fillers on the barrier properties of an epoxy-polyamido amine waterborne coating on a 2024 aluminium alloy. Four systems were studied: a clear coat and three pigmented coatings (with and without chromates). The results obtained by TSC highlight the specific action of chromates which decrease the molecular mobility (hardening) of the coating by comparison with neutral fillers. This has been explained by the high polarity of chromates that enhances interactions with the binder. Impedance measurements carried out for free-standing films and for coated aluminium alloy have corroborated the role of chromates on the barrier properties of the coating which remain high as a function of exposure time in a 0.5 M NaCl solution. TSC was also used to measure the glass transition temperature (T_g) of the hydrated systems. T_g was significantly decreased when the coatings were hydrated due to a strong plasticization effect induced by water uptake. For the different systems, we conclude that the weak barrier properties of the films (attached films) or the decrease of the barrier properties with time (free-standing films) were linked to the variation of the glass transition temperature by water uptake.     

Flue gas desulfurization by citrate process and optimization of working parameters

In this study, model flue gas was bubbled into 0.25 L tribasic sodium citrate (TSC) solution being in 0.5 L glass absorber to remove its SO₂ content. Size of gas bubbles, absorption temperature, gas flow rate, solution concentration and stirring rate were taken as working parameters to investigate their effect on SO₂ removal from flue gas. The Taguchi's experimental design method was used to obtain optimum values of working parameters for SO₂ saturation time of the TSC solution selected as a quality characteristic. The optimum levels of parameters to maximize the SO₂ saturation time of TSC solution were coarse bubbles for gas delivery, 35 °C for absorption temperature, 1.5 slm for gas flow rate, 0.5 M for TSC solution concentration and 500 rpm for stirring rate. Under these conditions, the SO₂ saturation time of the TSC solution was achieved as 511 min in average. The most effective parameters on the absorption of SO₂ in TSC solutions were ranked to the least as solution concentration, gas flow rate, size of gas bubbles, absorption temperature and stirring rate.     

Amino Acid-Mediated Intracellular Ca2+ Rise Modulates mTORC1 by Regulating the TSC2-Rheb Axis through Ca2+/Calmodulin

Mechanistic target of rapamycin complex 1 (mTORC1) is a master growth regulator by controlling protein synthesis and autophagy in response to environmental cues. Amino acids, especially leucine and arginine, are known to be important activators of mTORC1 and to promote lysosomal translocation of mTORC1, where mTORC1 is thought to make contact with its activator Rheb GTPase. Although amino acids are believed to exclusively regulate lysosomal translocation of mTORC1 by Rag GTPases, how amino acids increase mTORC1 activity besides regulation of mTORC1 subcellular localization remains largely unclear. Here we report that amino acids also converge on regulation of the TSC2-Rheb GTPase axis via Ca²⁺/calmodulin (CaM). We showed that the amino acid-mediated increase of intracellular Ca²⁺ is important for mTORC1 activation and thereby contributes to the promotion of nascent protein synthesis. We found that Ca²⁺/CaM interacted with TSC2 at its GTPase activating protein (GAP) domain and that a CaM inhibitor reduced binding of CaM with TSC2. The inhibitory effect of a CaM inhibitor on mTORC1 activity was prevented by loss of TSC2 or by an active mutant of Rheb GTPase, suggesting that a CaM inhibitor acts through the TSC2-Rheb axis to inhibit mTORC1 activity. Taken together, in response to amino acids, Ca²⁺/CaM-mediated regulation of the TSC2-Rheb axis contributes to proper mTORC1 activation, in addition to the well-known lysosomal translocation of mTORC1 by Rag GTPases.     

Fast preparation of citrate-stabilized silver nanoplates and its nanotoxicity

Citrate-stabilized silver nanoplates (AgNPs) were prepared via a seed-mediated method without surfactants, such as cetyltrimethylammonium bromide (CTAB), in a short amount of time (15 min). Silver seeds with 3–4 nm in diameter were added to a growth solution containing AgNO₃, trisodium citrate (TSC) and L-ascorbic acid (AA). The size of the AgNPs depended on the concentration of the silver seed and TSC. The physical properties of the AgNPs were analyzed by transmission electron microscopy (TEM) and by an ultraviolet-visible (UV-vis) spectrophotometer. In addition, we tested the nanotoxicity of AgNPs prepared in TSC solution to the spleen of a rat, and found that AgNPs induced inflammation and white spots on the surface of the spleen.     

Electrical properties and defect analysis of neutron irradiated undoped CVD diamond films

High-quality detector-grade CVD diamond films have been irradiated with fast neutrons up to 2×10¹⁵ n/cm² (1 MeV neutron-equivalent). Thermally stimulated currents (TSC) and thermoluminescence (TL) analysis have been performed. After irradiation, a decrease in the TSC and TL signal intensity is observed, while no significant changes in the spectrum shape are found. The TSC analyses have been performed as a function of the electric field and the results have been discussed in terms of the Poole–Frenkel effect.     

Chain and carrier mobility in polymer systems as investigated by thermally stimulated current techniques

Summary The results of TSC and TSD measurements carried out on polymers were analysed in terms of the influence of chain element motions on the release of charge carriers. Due to the relaxation processes occurring with increasing temperature the mobile chain elements shake off charge carriers leading to the charge release correlated with molecular mobility. This effect, called the wet dog effect, was shown in TSD and TSC experiments carried out on polycarbonate films doped with different amounts of suitable additives (antiplasticizers) and it was related to the chain mobility modification of detrapping phenomena. This study shows that a correlation between particular peak positions in TSC, TSD, TL experiments and carrier motion or dipolar relaxations must be done very carefully.From the International Seminar on Polymer Physics, High Tatra, CSSR, April 1982     

Synaptic Alterations in a Transgenic Model of Tuberous Sclerosis Complex: Relevance to Autism Spectrum Disorders

Tuberous sclerosis complex (TSC) is a rare, multi-system genetic disease with serious neurological and mental symptoms, including autism. Mutations in the TSC1/TSC2 genes lead to the overactivation of mTOR signalling, which is also linked to nonsyndromic autism. Our aim was to analyse synaptic pathology in a transgenic model of TSC: two-month-old male B6;129S4-Tsc2^tm1Djk/J mice with Tsc2 haploinsufficiency. Significant brain-region-dependent alterations in the expression of several synaptic proteins were identified. The most prominent changes were observed in the immunoreactivity of presynaptic VAMP1/2 (ca. 50% increase) and phospho-synapsin-1 (Ser62/67) (ca. 80% increase). Transmission electron microscopy demonstrated serious ultrastructural abnormalities in synapses such as a blurred structure of synaptic density and a significantly increased number of synaptic vesicles. The impairment of synaptic mitochondrial ultrastructure was represented by excessive elongation, swelling, and blurred crista contours. Polyribosomes in the cytoplasm and swollen Golgi apparatus suggest possible impairment of protein metabolism. Moreover, the delamination of myelin and the presence of vacuolar structures in the cell nucleus were observed. We also report that Tsc2^+/− mice displayed increased brain weights and sizes. The behavioural analysis demonstrated the impairment of memory function, as established in the novel object recognition test. To summarise, our data indicate serious synaptic impairment in the brains of male Tsc2^+/− mice.     

Characterization of energy levels related to impurities in epitaxial 4H-SiC ion implanted p+n junctions

The distribution of energy levels within the bandgap of epitaxial 4H-SiC p⁺/n junctions was studied. The junction was obtained by Al ion implantation on a nitrogen doped n-type epitaxial substrate. Thermally stimulated currents/capacitance (TSC/TSCAP) as well as current/capacitance deep level transient spectroscopy (I- and C-DLTS) were carried out over a wide temperature range (20–400 K). The two TSC/DLTS peaks associated with N-doping were detected for the first time and their trap signatures determined. Two hole traps relating to deep and shallow boron confirm that a boron contamination occurred during crystal growth. A negligible concentration of the Z_1/2 level, which is usually the dominant level produced by irradiation of ion implant, was measured. The concentrations of all observed traps were significantly lower than nitrogen one, which determines the doping. This evidence supports the high quality of the processed junctions, making these devices particularly attractive for future use in particle detection as well as in optoelectronic applications.     

Study on thermal transitions of toluene diisocyanate-based polyurethane elastomers with poly (tetramethylene oxide) as the soft segment by TSC/RMA, DSC and DMA thermal analyzers

Thermal transitions of TDI-based polyurethane elastomers with PTMO as the soft segment were characterized by the depolarization technique in TSC and by using with the thermal windowing technique on selected specimens in the RMA measurements. Results indicate that the broadened thermal transition in the glass transition region as observed in the DSC thermogram is related to the combined T_g transition and the T_global transition in the TSC spectrum. This T_global transition is associated with the macromolecular property as detected by tan δ in DMA measurement. The increase in the T_g with a high NCO content may be explained by the structural modification found on the urethanic chain with the additional linkage of the hard segment that affects the cooperative motion of the molecular chain. Data measured from DSC, TSC/RMA and DMA with simulated DEA and wide angle X-ray data are presented for the characterization of the polyurethanes. The RMA measurement leads to a compensation search on T_g transition and provides pertinent thermokinetic data that correlates the NCO content with changes in enthalpy and entropy on the relaxation behaviors in the T_g transition of polyurethane elastomers.     

低温乳聚丁苯橡胶反应器的稳态模拟

乳聚丁苯橡胶（ESBR）是最早实现工业化科耗量最大的合成橡胶胶种，对ESBR反应器的模拟一直是一难题。今在组分浓度分配、分析数据计算以及模型算法方面对现有反应器模型进行了改进，建立了能用于现场模拟的聚合釜模型。通过抽象为数个串联聚合釜的方法建立了置换塔模型，并确定了串联数目。讨论了总固体含量（TSC）和门尼粘度（ML）的模拟值与分析值间的差距，分析了引发剂、调节剂用量对ESBR产品质量的影响。结果表明，该模型能较好地反映和预测反应器的操作情况。     

Thermal stimulated current study of core-shell impact modifier/PVC blends

This study examines the efficacy of core-shell structure impact modifers, having different particle sizes and core/shell compositions, for modifying PVC's impact strength. The core and the shell's main compositions are polybutyl acrylate and polymethyl methacrylate, respectively. Also, the TSC is used to obtain the fundamental states of the blended impact modifier/PVC systems, thereby allowing them to be correlated to the above observed efficacy. Results of this study can provide valuable information toward exploring the feasibility of using the TSC data as a product development guide for designing PVC impact modifiers.     

Characterization of PVC/CPE blends by thermally stimulated current

In recent years, the use of polymer blends and alloys has become increasingly important in the development of advanced engineering materials. Through the combination of existing polymers, new and improved properties such as impact strength, chemical resistance, and increased temperature use range have been achieved. An important challenge has been to develop new analytical methods capable of properly evaluating these increasingly complex polymer systems. Careful examination of the blend morphology and degree of internal stress between phases is often critical to the success of the development of new blends and alloys. Blends of grafted and crosslinked PVC and CPE were evaluated by Thermally Stimulated Current (TSC). The extent of crosslinking and degree of interpenetration between the two phases were evaluated by examination of the glass transition peaks generated during the TSC experiments. The unique sensitivity of this technique provided excellent insight, which may allow prediction of long term stability and impact strength based on the degree of internal stress that exists at the phase boundaries. This paper explores the application of TSC as a development tool in the study of impact-modified PVC.     

Adsorption of thiosemicarbazide on copper cathodes

The adsorption of thiosemicarbazide (TSC) on cathodically polarised copper is studied. The adsorption follows the Flory-Huggins and the Bockris-Swinkels isotherms with a standard free energy of adsorption of about 20kJmol^?1. Four water molecules are displaced by each adsorbing TSC molecule. This is explained on the basis of molecular models.     

Biodegradable polymers. XI. Spectral,thermal, morphological,and biodegradability properties of environment‐friendly green plastics of soy protein modified with thiosemicarbazide

The demand for biodegradable polymers produced from renewable natural resources continues to grow as environmental concerns increase. Biodegradable plastics derived from agricultural feedstock are a new generation of materials capable of reducing the environmental impact in terms of energy consumption and greenhouse effect in specific applications to perform as traditional/conventional plastics when in use and are completely biodegradable within a composting cycle through the action of living/micro‐organisms. The objective of this study is to examine the potentiality and performance pattern of soy protein isolate (SPI) resin, modified with various concentrations of thiosemicarbazide (TSC), as a thermoplastic to substitute some conventional petroleum‐based plastics. The spectral, thermal, morphological properties and the biodegradability of the modified resin have been investigated. The spectral studies indicate that TSC is not crosslinked with the protein moiety; rather, it acts as a modifier. Thermogravimetric analysis of the modified material has been followed using a computer analysis method (LOTUS package) developed by us for assigning the degradation mechanism. A number of equations have been used to evaluate the kinetic parameters. The degradation mechanism has been ascertained on the basis of the kinetic parameters. It is expected that, this environment‐friendly, fully biodegradable and sustainable TSC‐modified SPI green plastic could be commercially used for making molded products. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3134–3142, 2007