Pulsed-radio frequency plasma enhanced chemical vapour deposition of low temperature silicon nitride for thin film transistors

The growth of low temperature silicon nitride using radio frequency (RF) plasma enhanced chemical vapour deposition (PECVD) is associated with high porosity and surface roughness due to the short surface diffusion length of adsorbed radicals during the deposition. In this work we present pulsed-RF PECVD as a means of achieving a film with smoother surface and reduced density of voids. The growth process and the longer surface diffusion length are discussed as the main reason behind improvement of film density while maintaining the substrate temperatures. The deposited films exhibit improved electrical performance with 72% reduction in breakdown probability compared with conventional continuous-wave RF PECVD films. A low interfacial defect density with a field effect mobility of 1.1 cm²/V.s and subthreshold slope of 0.3 V/dec, was achieved when used as a gate dielectric in thin film transistors.     

Practical Considerations of Dissolved Oxygen Levels for Platelet Function under Hypoxia

Investigating human platelet function in low-oxygen environments is important in multiple settings, including hypobaric hypoxia (e.g., high altitude), sea level hypoxia-related disease, and thrombus stability. These studies often involve drawing blood from which platelets are isolated and analysed at atmospheric conditions or re-exposed to low oxygen levels in hypoxia chambers before testing. However, it remains unknown how the in vitro handling of the samples itself changes their dissolved oxygen concentration, which might affect platelet function and experimental results. Here, we prepared healthy donor platelet-rich plasma and washed platelet (WP) suspensions and exposed them to 2% oxygen. We found that the use of hypoxia pre-equilibrated tubes, higher platelet concentrations (>2 × 10⁸/mL versus 2 × 10⁷/mL), smaller volumes (600 µL versus 3 mL), and presence of plasma reduced the time for samples to reach 2% oxygen. Notably, oxygen levels decreased below 2% in most suspensions, but also in WP maintained at atmospheric 21% oxygen. Additionally, platelet spreading on fibrinogen was decreased when using hypoxic fibrinogen-coated culture plates regardless of the oxygen percentage (2% or 21%) in which platelet incubation took place. Thus, sample handling and experimental conditions should be carefully monitored in platelet-hypoxia studies as they might compromise results interpretation and comparison across studies.     

Recent Advances in Gene Therapy for Cardiac Tissue Regeneration

Cardiovascular diseases (CVDs) are responsible for enormous socio-economic impact and the highest mortality globally. The standard of care for CVDs, which includes medications and surgical interventions, in most cases, can delay but not prevent the progression of disease. Gene therapy has been considered as a potential therapy to improve the outcomes of CVDs as it targets the molecular mechanisms implicated in heart failure. Cardiac reprogramming, therapeutic angiogenesis using growth factors, antioxidant, and anti-apoptotic therapies are the modalities of cardiac gene therapy that have led to promising results in preclinical studies. Despite the benefits observed in animal studies, the attempts to translate them to humans have been inconsistent so far. Low concentration of the gene product at the target site, incomplete understanding of the molecular pathways of the disease, selected gene delivery method, difference between animal models and humans among others are probable causes of the inconsistent results in clinics. In this review, we discuss the most recent applications of the aforementioned gene therapy strategies to improve cardiac tissue regeneration in preclinical and clinical studies as well as the challenges associated with them. In addition, we consider ongoing gene therapy clinical trials focused on cardiac regeneration in CVDs.     

Subset simulation method including fitness-based seed selection for reliability analysis

Probability estimation of rare events is a challenging task in the reliability theory. Subset simulation (SS) is a robust simulation technique that transforms a rare event into a sequence of multiple intermediate failure events with large probabilities and efficiently approximates the mentioned probability. Proper handling of a reliability problem by this method requires employing a suitable sampling approach to transmit samples toward the failure set. Markov Chain Monte Carlo (MCMC) is a suitable sampling approach that solves the SS transition phase using the failed sample of each simulation level as the seed of next samples. This paper is aimed to study the seed selection effect on the SS accuracy through several seed selection approaches inspired by the genetic algorithm and particle filter and using the main PDF of the variables to assign a mass function probability to each subset sample in the failure domain. Roulette wheel (I, II), tournament and proportional probability techniques are then employed to choose the weighed samples as seeds to be placed in the MCMC to transmit the samples. To examine the capability of each approach, reliabilities of some engineering problems were investigated and results showed that the proposed approaches could find proper failure sets better than the original SS method, especially in problems with several failure domains.

     

Silicone secondary cross-linked IPN based on poly(vinylacetate-co-hydroxyethyl methacrylate) and SiO2

Silicone secondary cross-linked interpenetrating polymer networks (IPNs) of poly(vinylacetate-co-hydroxyethyl methacrylate) (PVAc-HEMA) and SiO₂ were prepared by free radical polymerization and condensation methods. The resulting copolymers were characterized by using Fourier transform infrared spectroscopy (FTIR). Thermal properties of the copolymers were studied by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology of copolymers was also investigated by optical microscopy (OM) and then the effects of silicone concentrations, the reflux time, and composition on the phase morphology of the IPNs of PVAc-HEMA/SiO₂ were discussed. The broadening of the transition region was observed with the increase of the prolongation of the reflux time and the tendency of the aggregation of silicon in the surface was also observed with Teflon as a substrate plate. However, an optically transparent film was easily achieved at higher temperature due to the chemical cross-link and physical entanglement between the two phases of PVAc-HEMA and SiO₂.     

Immobilization of glucose oxidase on 3D graphene thin film: Novel glucose bioanalytical sensing platform

Electrochemical biosensors are responsible for quantification of analytes for medical diagnostics applications. They are considered as a promising means to investigate the content of a biological sample owing to the direct exchange of a biological process to an electronic output signal. Novel characteristics of nanocarbon materials attracted much attention for fabrication of numerous electrochemical biosensors with developed analytical capacities. This paper aims to provide perceptions of 3D graphene-based electrochemical biosensors and to demonstrate its application in glucose detection. The developed glucose biosensing platform exhibits excellent catalytic activity towards glucose detection over a wide linear range of up to 6 mM with sensitivity of 1.63 μA mM^?1 cm^?2 and the stability of electrode is around 76.9% after one month. The facile and easy electrochemical approach used for the preparation of 3DG–GOD modified GCE may open up new horizons in the production of cost-effective biosensors.     

Investigation of Lake Sapanca water pollution,Adapazari, Turkey

Lake Sapanca has been the only source of drinking and recreational water for the city of Adapazari, Turkey. This paper reports a study of the variation of nutrient loading and trophic state of the lake, and also water quality parameters of Lake Sapanca compared to those of the neighbouring Lake Iznik. Through one year, samples were taken every three months from 15 different points on the streams feeding and draining off the lake. Nitrate, NO₂‐N, NH₃‐N, TKN, PO₄‐P concentrations on the 12 streams fe and three draining off points were determined. Then, loading, discharge, and accumulation amounts of nitrogen and phosphorus causing eutrophication were calculated and the trophic state of the lake was determined. A simple model was used to analyse the response of Lake Sapanca when the phosphorus loading rate was changed. Through this model, the variation of different parameters (t, M, K, Q, V and A) with respect to phosphorus concentration (C) was studied to identify effects and results. The consequences of an eutrophic state and measures to protect the lake are also discussed.     

The influence of heat treatment on the microstructure,flux pinning and magnetic properties of bulk BSCCO samples prepared by sol-gel route

We study the combined influence of calcination and sintering temperature on the microstructure, superconducting and pinning properties of Bi_1.6Pb_0.4Sr₂Ca₂Cu₃O_10+θ (Bi-2223) prepared by the sol-gel route. Using several characterization techniques, including X-rays diffractometry and electrical transport measurements, we find that the powders calcined at 820 °C often result in a crystal higher critical current density (J_c) compared those calcined at 830 °C. The powder calcined at 820 °C and sintered at 850 °C (Bi-2223 ₈₂₀⁸⁵⁰) showed the best grain morphology and the largest magnetic hysteresis loop and a J_c equal to 12.94 $\times$ 10⁵ A/cm², comparable to the best results found in the literature for Bi-2223. The enhancement in J_c for Bi-2223 ₈₂₀⁸⁵⁰ seems to be due to improved grain structure rather than creation of effective pinning centers, because the scaling behavior of flux pinning force densities indicates that the main pinning mechanism for all samples is normal point pinning.