MicroRNA Expression Profile in TSC Cell Lines and the Impact of mTOR Inhibitor

The aim of this study was to assess the potential implication of microRNA on tuberous sclerosis (TSC) pathogenesis by performing microRNA profiling on cell lines silencing TSC1 or TSC2 genes using qPCR panels, before and after incubation with rapamycin. Significant differences in expression were observed between samples before and after rapamycin treatment in nineteen miRNAs in TSC1, five miRNAs in TSC2 and seven miRNAs in controls. Of miRNAs dysregulated before rapamycin treatment, three normalized after treatment in the TSC1 group (miR-21-3p, miR-433-3p, let-7g-3p) and one normalized in the TSC2 group (miR-1224-3p). Of the miRNAs dysregulated before rapamycin treatment in the TSC1 and TSC2 groups, two did not normalize after treatment (miR-33a-3p, miR-29a-3p). The results of the possible targets indicated that there are four common genes with seed regions susceptible to regulation by those miRNAs: ZBTB20, PHACTR2, PLXNC1 and ATP1B4. Our data show no changes in mRNA expression of these targets after rapamycin treatment. In conclusion, results of our study indicate the involvement of miRNA dysregulation in the pathogenesis of TSC. Some of the miRNA might be used as markers of treatment efficacy and autonomic miRNA as a target for future therapy.     

Thermally stimulated creep of polyethylene,polypropylene, copolymers,and blends

The technique of Thermo Stimulated Creep (TSC) has been applied to the study of anelastic properties of polyethylene, polypropylene, their copolymers and blends. In the temperature range ?200 to 100°C, complex TSC peaks were observed in all samples, namely around 0°C, about the same temperature as for the homopolypolymer polypropylene. By applying “fractional stresses”, with a convenient choice or the loading program, these peaks have been experimentally resolved. Two components can be distinguished: 1. The “low temperature” component is characterized by mechanical retardation times following a compensation law. It has been attributed to microbrownian motions of polypropylene sequences liberated at the glass transition of the “true” amorphous regions. 2. The “high temperature” component which is influenced by thermal treatment has been assigned to microbrownian motions of polypropylene sequences liberated at the glass transition of the “constrained” amorphous regions. In block polymers, an additional TSC peak is observed around ?50°C: it has been associated with the glass transition of ethylene-propylene-rubber (EPR) interphase. The coupling of this interphase with polyethylene and polypropylene phases is insured by diffusion of some ethylene and propylene sequences in-EPR. At about ?140°C, a TSC peak associated with the low temperature component of the glass transition of polyethylene can be distinguished in all the materials studied.     

Thermally stimulated current of iodine-doped acrylonitrile–butadiene–styrene thin films

Structural change of acrylonitrile–butadiene–styrene (ABS) terpolymer due to iodine doping has been reported using both infrared (IR) and thermally stimulated current (TSC) techniques. IR investigation revealed the presence of a new stretching band at 640 cm^?1 that indicates the formation of the C-I structure. The TSC spectrum consists of two different decaying charge distributions of opposite polarity, which simply superpose to yield the net current observed. The variation of the position of the negative peak relaxation and its intensity as the iodine percentages increases indicates the formation of different ionic iodine species. The induced ionic dipoles superpose the α-relaxation of ABS. © 1993 John Wiley & Sons, Inc.     

Aging effect in Er3+-doped 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 ceramics

Usually, aging in poled ferroelectrics leads to degradation of certain physical properties. In this study, we found a remarkable aging effect in tetragonal Er³⁺-doped 0.5Ba(Zr_0.2Ti_0.8)O₃–0.5(Ba_0.7Ca_0.3)TiO₃ (BZT-BCT) ceramics after poling. It is observed that the domains can spontaneously rotate to keep their spontaneous polarization direction similar to that of the poling electric field during aging for the poled ceramics. Furthermore, compared with freshly poled ceramics, the thermally stimulated current (TSC) peak of the aged ones shifts toward a higher temperature (10°C). And the temperature of the TSC peak in the aged ceramics is exactly equal to their Curie temperature. Such features indicate that aging for the poled ceramics could stabilize the alignment of ordered ferroelectric domains. Additionally, a downward TSC peak above Curie temperature is obtained in both poled and aged ceramics, demonstrating that poling and aging can lead to ordered alignment of defect dipoles. The aging mechanism of poled Er³⁺-doped BZT-BCT ceramics has proposed and discussed in this article.     

Thermally stimulated current studies on molecular relaxation and blow moulding of poly(ethylene terephthalate)

The thermally stimulated current (TSC) technique has been used to investigate molecular relaxation in poly(ethylene terephthalate) (PET) films unstretched and biaxially stretched at 90 and 95 °C. Unstretched PET films show two peaks at 77 and 90 °C corresponding to α and ρ relaxation processes, respectively. The α relaxation is associated with the main glass transition of the material. The ρ peak with lower intensity is attributable to permanent dipoles. Both biaxially stretched samples show one TSC peak at 95 °C, supposed to correspond to ρ relaxation. The disappearance of the α peak, accompanied by the displacement of the ρ peak to higher temperature, is the result of the higher thermal stability of the permanent dipoles, which is strongly influenced by the stiffening of amorphous parts and the crystallization by stretching. In both stretched samples, the continuous distribution of pre-exponential factors over activation energies observed might correspond to a single relaxation mode. The kinematics of stretching PET has been discussed in terms of activation energy and temperature dependence of relaxation time. © 1999 Society of Chemical Industry     

Spontaneous polarization of polymer blends

A hypothesis on the formation of a non-equilibrium in electrical respect structure in blend compositions induced by generation of free charge carriers and their entrapment during extrusion has been put forward. The electret-thermal analysis (ETA) commonly employed to study electrical polarization of dielectrics has been for the first time used to analyze structures of multicomponent polymer blends. Blend composites turned to have characteristic spectra of thermally stimulated currents (TSC). Potentialities of the ETA have been studied on the polyamide-polyethylene blends containing a compatibilizer—bimodal polyethylene functionalized by maleic anhydride. Peaks on TSC spectra have been identified for each component content and their distribution in the blend. Thermomechanical processing of the studied blends even using specific intensive mixing methods (static and dynamic mixing) did not result in the formation of any new chemical compounds. A conclusion has been derived that the formation of electrically non-equilibrium structure is naturally intrinsic for polymer blend composites.     

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.     

Instability of the Characteristics of the Positive Temperature Coefficient of Resistivity in High-Curie-Point Barium-Lead Titanate Ceramics and Their Grain Structures

A significant isothermal increase in resistivity with time has been observed in high-Curie-point barium-lead titanate ceramics in the temperature region of the Curie points, giving rise to an instability of the characteristics of the positive temperature coefficient of resistivity (PTCR). The isothermal increase in resistivity (ρ) with time (t) observed at various temperatures can be expressed by the equation log ρ=A+B√t, where A and B are both temperature-dependent constants. The temperature dependence of A gave the usual PTCR characteristics because A is log ρ at t=0, while the temperature dependence of B was found to show a characteristic curve with a peak around the Curie point. Observation by SEM revealed a considerable difference between the grain structure of a sample showing a significant resistivity change and that of a sample showing little resistivity change.     

硼硅酸盐玻璃成分对硫酸钡热稳定性的影响

研究了硼硅酸盐玻璃主要成分(SiO2、Na2O、B2O3)对硫酸钡(BaSO4)热稳定性的影响,分析BaSO4分别与SiO2、Na2O、B2O3的混合物在不同温度(800~1 200℃)煅烧后的物相组成、显微结构、硫含量和拉曼光谱。结果表明:当BaSO4:SiO2摩尔比为7.5:92.5 (样品A)时,在温度低于1 200℃煅烧后其物相均为BaSO4和SiO2,温度达到1 200℃时出现了少量硅钡石(BaSi2O5)相;当BaSO4:SiO2:Na2O为7:86:7 (样品B)时,在800℃煅烧后即出现了少量BaSi2O5相,当温度达到1200℃时样品主要物相为BaSi2O5和方石英,硫含量明显减少;当BaSO4:SiO2:Na2O:B2O3为5.5:67.5:6.5:21.5 (样品C)时,在800~1 200℃均为BaSO4和SiO2,在1 200℃保温2h后,BaSO4和SiO2的衍射峰基本消失。低熔点的Na2O和B2O3的引入促进了BaSO4的分解,在1 200℃煅烧后,样品A、B、C中SO4四面体的拉曼特征峰依次减弱。     

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     

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.     

Primary TSC2-/meth Cells Induce Follicular Neogenesis in an Innovative TSC Mouse Model

Cutaneous lesions are one of the hallmarks of tuberous sclerosis complex (TSC), a genetic disease in which mTOR is hyperactivated due to the lack of hamartin or tuberin. To date, novel pharmacological treatments for TSC cutaneous lesions that are benign but still have an impact on a patient’s life are needed, because neither surgery nor rapamycin administration prevents their recurrence. Here, we demonstrated that primary TSC2^-/meth cells that do not express tuberin for an epigenetic event caused cutaneous lesions and follicular neogenesis when they were subcutaneously injected in nude mice. Tuberin-null cells localized in the hair bulbs and alongside mature hairs, where high phosphorylation of S6 and Erk indicated mTOR hyperactivation. Interestingly, 5-azacytidine treatment reduced hair follicles, indicating that chromatin remodeling agents might be effective on TSC lesions in which cells lack tuberin for an epigenetic event. Moreover, we demonstrated that the primary TSC2^-/meth cells had metastatic capability: when subcutaneously injected, they reached the bloodstream and lymphatics and invaded the lungs, causing the enlargement of the alveolar walls. The capability of TSC2^-/meth cells to survive and migrate in vivo makes our mouse model ideal to follow the progression of the disease and test potential pharmacological treatments in a time-dependent manner.     

TSC study of length ester side group effect on sub-vitreous relaxations in poly(n-alkyl methacrylates)

A comparative study by thermo-stimulated currents (TSC) of three poly(n-alkyl methacrylates) is performed. TSC complex spectra exhibit two dipolar relaxations considered in the following: the glass relaxation and a secondary relaxation related to motion of ester side groups. For each sample, the fractional polarisations protocol is applied to describe the fine structure of these complex spectra. It allows us to define the evolution of activation parameters with temperature. The influence of side chain architecture is then considered. It emphasises that the β mode is independent of the ester group length. On the contrary, the α mode is highly sensitive to structural change. These results are finally explained in terms of molecular mobility.     

Thermally stimulated current characteristics of polypropylene with an without glass fibres

Summary Small discs of melt-pressed polypropylene (PP), drawn polypropylene sheet (natural draw ratio 5.5) and short glass fibre-reinforeed polypropylene sheet were polarized in a d.e. field at 100°C for 1 hr. Thermally stimulated depolarization current (TSC) characteristics of the polarized discs were studied from 50 to 170°C. The isotropic sample shows two peaks around 75 and 110°C and these peaks shift to 100 and 140°C respectively for the drawn sample. The TSC peaks of glass fibre-reinforced PP sheet are close to those of the isotropic sample but the current emitted is much higher even though it was polarized at a lower field. It is proposed that the large interface areas between the glass fibres and polypropylene matrix can accumulate charge and lead to the observed enhancement of the depolarization current.     

变温红外光谱法研究聚氨酯固化

提出利用红外光谱仪可控温附件研究丙烯酸聚氨酯树脂的固化过程。将热固性丙烯酸树脂(BS-965)作为A组分,异氰酸酯固化剂(740D)作为B组分,以一定质量比(如:A∶B=3∶1)的聚氨酯样品为例,当固化温度为120℃时,每隔5 min进行1次红外光谱扫描,通过测定官能团—NCO的特征峰2 272 cm-1透射率的变化,根据公式直接计算并得到反映热固性树脂固化程度的转化率曲线。该方法在一定温度下,只需1次制样,且不需要参比峰,使对聚氨酯固化的研究更方便、有效。     

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.     

The possibility of supercritical fluid regeneration for Pt-Re/γ-Al2O3 industrial reforming catalyst in O3/CO2 mixtures

This work continues a cycle of studies aimed at developing new approaches to the regeneration of coked bimetallic heterogeneous catalysts. The activities of three Ru-125 (Pt-Re/γ-Al₂O₃) industrial reforming catalyst samples (fresh catalyst (A), catalyst removed from an industrial reactor (B), and sample B after treating it with ozone in supercritical carbon dioxide (SC-CO₂) (C)) are been compared in the reforming of n-heptane. It is established that sample B is deactivated appreciably: the conversion of n-heptane and the yield of reforming products are generally much lower than on the fresh catalyst. After treating it with an O₃/SC-CO₂ mixture, the conversion of n-heptane not only returns to the level of fresh sample A, but also exceeds it by a factor of 1.2. The qualitative composition of the products obtained on samples A, B, and C is nearly the same, but there are some changes in the quantitative ratio of certain products. Regeneration with ozone is found to be promising for further development and scaling.     

Thermally stimulated discharge current studies on low-temperature relaxations in polycarbonate

The β-relaxation in polycarbonate has been investigated by the thermally stimulated discharge current (TSC) technique. The polarization of the β-peak in polycarbonate is shown to be uniform. Two broad peaks centered at 130° and 200°K were observed. Furthermore, two single relaxation processes were resolved for the lower temperature peak. The high temperature peak was also resolved into two peaks, however, only one of them was a single relaxation process. The individual peaks satisfied the dipolar theory, and the three peaks are associated with activation energies of 0.24, 0.27, and 0.47 eV, and temperatures of the peak maxima were 121°, 131°, and 193°K, respectively. The mechanism attributed to each peak is discussed and does not appear to contradict the results of conventional dielectric and mechanical relaxation and NMR measurements on the β-relaxation in polycarbonate.     

Thermo‐oxidative degradation behavior of recycled polypropylene

This study has been carried out to mimic the thermo‐oxidative degradation of polypropylene (co‐PP) during service life and recycling. Injection molded specimens were heat aged at 130°C for different times up to maximum of 300 h to simulate the degradation of co‐PP during the service life. These aged specimens were mixed with stabilizers in internal mixer and again heat aged up to 300 h. A small increase in melt flow rate (MFR) value was observed for aged co‐PP but it showed large increase after recycling. The presence of carbonyl peak at 1713 cm⁻¹ confirmed the oxidation of co‐PP during aging and it increases with aging time. Carbonyl index (CI) is increased in recycled sample with aging, whereas oxidation induction time (OIT) decreased. The stabilizers used during reprocessing are quite effective in controlling the thermo‐oxidative degradation of the polymer during processing and aging. The thermogravimetric analysis shows that the onset of degradation temperature starts at low temperature for recycled sample as compared to virgin co‐PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011