This letter proposes a new organic trench structure which can enhance the endurance of polycrystalline silicon thin film transistors (TFTs) under mechanical bending stress. It compares conventional ...structure TFTs to devices with an organic trench to examine reliability after undergoing 100,000 iterations of channel width-axis (100,000'WC) compression at R = 2mm. Due to the low Young's modulus of organic materials, stress while undergoing bending strain is desorbed to the buffer layer, which can lower the overall stress in TFTs. Furthermore, an optimal location and ideal length for such an organic trench is evaluated by mechanical bending simulation.
This letter investigates variations in polycrystalline silicon thin film transistor (TFT) performance under illumination and negative bias temperature instability (NBTI) tests due to different ...dehydrogenation annealing temperatures during the fabrication process. The depth of the density of state (DOS) in polysilicon can be indirectly determined by the TFT response to light illumination, since dangling bonds act as recombination centers. The electrical characteristics of TFTs after undergoing NBTI can also be indicative of the bonding type of silicon atoms. By analyzing the results of these reliability tests, the type of DOS can be clarified, which is beneficial for realizing the relationship between performance and reliability.
In recent years remarkable progress has been made towards the understanding of proposed hallmarks of cancer development and treatment. However with its increasing incidence, the clinical management ...of cancer continues to be a challenge for the 21st century. Treatment modalities comprise of radiation therapy, surgery, chemotherapy, immunotherapy and hormonal therapy. Radiation therapy remains an important component of cancer treatment with approximately 50% of all cancer patients receiving radiation therapy during their course of illness; it contributes towards 40% of curative treatment for cancer. The main goal of radiation therapy is to deprive cancer cells of their multiplication (cell division) potential. Celebrating a century of advances since Marie Curie won her second Nobel Prize for her research into radium, 2011 has been designated the Year of Radiation therapy in the UK. Over the last 100 years, ongoing advances in the techniques of radiation treatment and progress made in understanding the biology of cancer cell responses to radiation will endeavor to increase the survival and reduce treatment side effects for cancer patients. In this review, principles, application and advances in radiation therapy with their biological end points are discussed.
This study uses an optimization approach representation and numerical solution for the variable viscosity and non-linear Boussinesq effects on the free convection over a vertical truncated cone in ...porous media. The surface of the vertical truncated cone is maintained at uniform wall temperature and uniform wall concentration (UWT/UWC). The viscosity of the fluid varies inversely to a linear function of the temperature. The partial differential equation is transformed into a non-similar equation and solved by Keller box method (KBM). Compared with previously published articles, the results are considered to be very consistent. Numerical results for the local Nusselt number and local Sherwood number with the six parameters (1) dimensionless streamwise coordinate ξ, (2) buoyancy ratio N, (3) Lewis number Le, (4) viscosity-variation parameter θ r , (5) non-linear temperature parameter δ 1 , and (6) non-linear concentration parameter δ 2 are expressed in figures and tables. The Taguchi method was used to predict the best point of the maxima of the local Nusselt (Sherwood) number of 3.8636 (5.1156), resulting in ξ (4), N (10), Le (0.5), θ r (−2), δ 1 (2), δ 2 (2) and ξ (4), N (10), Le (2), θ r (−2), δ 1 (2), δ 2 (2), respectively.
Previous studies have reported associations between hearing impairment (HI) and cognitive impairment, but the evidence is not conclusive while considering concurrent geriatric syndromes. Especially, ...evidence from previous studies rarely came from Asian studies. This study aimed to evaluate the independent effects of HI and hearing aid use on the incidence of cognitive impairment while considering most geriatric confounders.
This population-based, propensity-score matched cohort study used cohort from Waves IV-VII (1999-2011) survey of the Taiwan Longitudinal Study on Aging (TLSA). Cognitive impairment was identified based on Short Portable Mental Status Questionnaire (SPMSQ) scores. The hazard ratio (HR) was calculated using the Cox proportional hazard regression adjusting for age, sex, comorbidities, socioeconomic status, Center for Epidemiologic Studies Depression (CES-D) scores, the instrumental activities of daily living scale, mobility condition and quality of life. In addition, social support and participation were also considered as confounders in the analysis. To assess the robustness of our findings, we conducted a sensitivity analysis designed to access unmeasured confounding factors by calculating E-values.
After 1:1 propensity-score matching, we included 709 participants in both the HI and non-HI groups with a mean age of 73.4 years and 39.4% of participants were female. The mean follow-up was 8.9 ± 3.9 years. The HI group had a higher incidence of cognitive impairment than the non-HI group (74.5% vs. 69.1%, respectively), with an adjusted HR of 1.16 (95% confidence interval CI, 1.03-1.32) based on a 12-year follow up. The E-value was 1.45 for the estimate, which provided evidence for this study's robustness. Although, a subgroup analysis showed that hearing aid use was associated with lower incidences of cognitive impairment (66.3% vs. 75.6%) when compared to non-users in the HI group, the adjusted HR of 0.82 (95% CI, 0.61-1.09) revealed no significant differences.
HI was an independent risk factor of incident cognitive impairment on top of concurrent geriatric syndromes. Early HI detection may thus be effective for preventing cognitive decline. Further studies are needed to evaluate the effect of hearing aid use on the prevention of cognitive decline.
This letter investigates degradation behaviors induced by the self-heating effect for amorphous indium-gallium-zinc-oxide (IGZO) (a-IGZO) thin-film transistors (TFTs). Both the surrounding oxide and ...other thermal insulating material and the low thermal conductivity of the IGZO layer itself cause the self-heating effect in a-IGZO TFTs. The heated channel layer enhances threshold voltage shift, and the evolution of threshold voltage shift is found to be dominated by charge-trapping effect. Further verifications indicate that the degree of threshold voltage shift is dependent on stress power only, and a wider channel leads to more severe self-heating effect.
This paper systematically studies high-current-induced effects, hot-carrier effects, and self-heating effects in flexible low-temperature polycrystalline-silicon thin-film transistors fabricated on ...polyimide. By utilizing I-V and various-frequency C-V measurements, the exact location of defects generated by the self-heating effects can be clarified. The degradation mechanism is found to originate from asymmetric negative-bias temperature instability. After clarifying this mechanism, the self-heating effects were shown to be alleviated by manipulating the fabrication of the buffer layer, thereby improving heat dissipation capabilities.
At bending radius smaller than 2 mm, flexible low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs) suffer from strong uniaxial mechanical stress and demonstrate severe ...degradation of electrical characteristics. Our previous study showed that repetitive mechanical uniaxial bending damages the gate insulator, causing carriers to trap into it. Here, degradation after channel width-axis direction bending was found to be more pronounced than after channel length-axis bending. In order to alleviate this degradation, an organic structure flexible LTPS TFT was proposed to enhance the mechanical stress endurance. After 100000 iterations of uniaxial mechanical bending at <inline-formula> <tex-math notation="LaTeX">{R} = 2 </tex-math></inline-formula> mm, degradation nearly disappeared in devices with this organic trench structure.
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