This study aims to optimize the mechanical and electrical properties of electrically conductive polymer composites (CPCs) for use as a material of bipolar plates for PEM fuel cells. The thin CPCs consisting of conductive fillers and polymer resin were fabricated by a preform molding technique. Expanded graphite (EG), flake-type graphite (FG) and carbon fiber (CF) were used as conductive fillers. This study tested two types of CPCs, EG/FG filled CPCs and EG/CF filled CPCs, to optimize the material properties. First, the characteristics of EG/FG filled CPCs were investigated according to the FG ratio for 7 and 100 µm sized FG. CPCs using 100 µm FG showed optimal material properties at 60 wt% FG ratio, which were an electrical conductivity of 390 S/cm and flexural strength of 51 MPa. The particle size was an important parameter to change the mechanical and electrical behaviors. The flexural strength was sensitive to the particle size due to the different levels of densification. The electrical conductivity also showed size-dependent behavior because of the different contributions to the conductive network. Meanwhile, the material properties of EG/CF filled CPCs was also optimized according to the CF ratio, and the optimized electrical conductivity and flexural strength were 290 S/cm and 58 MPa, respectively. The electrical conductivity of this case decreased similarly to the EG/FG filled case. On the other hand, the behavior of the flexural strength was more complicated than the EG/FG filled case, and the reason was attributed to the interaction between the strengthening effect of CF and the deterioration of voids.
Temperature (T) dependent transport measurements of cylindrical shaped gate-all-around silicon nanowire MOSFETs (SNWFETs) were performed. Single electron tunneling behaviors were observed at 4.2 K and one of the devices exhibited anomalously strong current peak which survived even at room temperature. The observed peak was interpreted as an evidence of transport through single impurities in the channel.
In this letter, we report over 50% enhancement in optical coupling tolerance between a single-mode fiber and a photodiode. The enhancement is made possible by integrating a microlens on the polished backside of an InGaAs photodiode device. The microlenses are fabricated by one step wet chemical etching in the mixed solution of bromic acid and hydrogen peroxide. Surface profiles of the microlenses are simulated using the finite-difference-method to solve a simplified diffusion model. The optical coupling tolerance is also theoretically calculated based on ray optics, of which results show an excellent agreement with the experimental data.
Pituitary apoplexy is a rare but life-threatening disorder.Clinical presentation of this condition includes severe headaches, impaired consciousness, fever, visual disturbance, and variable ocular paresis.The clinical presentation of meningeal irritation is very rare.Nonetheless, if present and associated with fever, pituitary apoplexy may be misdiagnosed as a meningitis.We experienced a case of pituitary apoplexy masquerading as a meningitis.A 42-year-old man presented with meningitis associated symptoms and initial imaging studies did not show evidence of intra-lesional hemorrhage in the pituitary mass.However, a follow-up imaging after neurological deterioration revealed pituitary apoplexy.Hereby, we report our case with a review of literatures.
Objectives: This study aimed to compare the demographic characteristics, responses to negative emotions, and difficulties in emotion regulation between self-harming adolescents and control individuals aged 12-14 years from the community.Methods: Data were collected from adolescents in Chungcheong Province, South Korea, between September 2021 and November 2022.Demographic characteristics and responses to the Depressed Mood Questionnaire and Difficulties in Emotion Regulation Scale-16 (DERS-16) were compared between the self-harm and control groups.Results: The self-harm group exhibited a higher prevalence of child abuse (odds ratio [OR]=4.787,95% confidence interval [CI]=1.591-14.409,p=0.005) and school bullying victimization (OR=4.495,95% CI=2.353-8.588,p<0.001) than those in the control group.The selfharm group displayed higher levels of rumination (t=7.88,p<0.001) and reduced distraction responses (reverse score t=2.25, p=0.025) than those of the control group.Additionally, the self-harm group scored higher on all subscales and the total DERS-16 score (t=7.61,p<0.001).Conclusion: Interventions for self-harming adolescents should address child abuse and bullying victimization.Prevention programs for self-harming adolescents should focus on reducing rumination responses, increasing distractive responses, and addressing difficulties in emotion regulation using dialectical behavior therapy-skill training.
A mixture of docetaxel (DTX) and Solutol(®) HS 15 (Solutol) transiently formed nanodroplets when it was suspended in an aqueous medium. However, nanodroplets that comprised DTX and Solutol showed a rapid precipitation of DTX because of their unstable characteristics in the aqueous medium. The incorporation of nanodroplets that comprised DTX and Solutol through vesicle fusion and subsequent stabilization was designed to prepare multilayer nanoparticles (NPs) with a DTX-loaded Solutol nanodroplet (as template NPs) core for an efficient delivery of DTX as a chemotherapeutic drug. As a result, the DTX-loaded Solutol nanodroplets (~11.7 nm) were observed to have an increased average diameter (from 11.7 nm to 156.1 nm) and a good stability of the hydrated NPs without precipitation of DTX by vesicle fusion and multilayered structure, respectively. Also, a long circulation of the multilayer NPs was observed, and this was due to the presence of Pluronic F-68 on the surface of the multilayer NPs. This led to an improved antitumor efficacy based on the enhanced permeation and retention effect. Therefore, this study indicated that the multilayer NPs have a considerable potential as a drug delivery system with an enhanced therapeutic efficacy by blood circulation and with low side effects.
There is no clear treatment strategy for the management of multiple intracranial aneurysms because of variable anatomical distribution, difficult identification of the aneurysm ruptured, and poor overall outcomes. The purpose of this study was to assess the efficacy and safety of single-session coil embolization for multiple intracranial aneurysms.Between September 2008 and December 2012, 209 aneurysms in 117 patients were treated at our institute. Twenty eight among the 117 patients had multiple aneurysms with a total of 71, and 60 of the 71 aneurysms underwent coil embolization in a single-session.A total of 60 aneurysms were treated with a single-session coil embolization, of which the most frequent locations were in the posterior communicating artery, followed by the middle cerebral artery. Immediate post-embolization angiographies showed total occlusion in 49 (81.7%) aneurysms, remnant neck in 6 (10%), and body-filling in 5 (8.3%). Procedure-related complications had developed in 2 (3.3%) of the 60 embolized aneurysms: an asymptomatic thromboembolic event, and a partial coil protrusion without a subsequent thromboembolic complication.With careful evaluation of individual aneurysm characteristics and configuration, multiple intracranial aneurysms previously thought to require multimodality therapy can be safely treated in a single-session coil embolization.
In a fuel injection engine, atomization of liquid fuel and mixture formation process has influenced(or affected) directly on the engine performance and pollutant emission. In this study, the characteristics of fuel spray and the behaviors of secondary atomization developed at the downstream of the valves were investigated using an image processing method. Solid and perforated valves are chosen in order to evaluate the valve performance in terns of air flow rate, valve opening angle and valve shape. Experimental results clearly indicate that the spray atomization quality can be improved by increasing the perforated rat io and the blockage rat io in the perforated valve, the characteristics of spray atomization is improved by using the perforated valve with high perforated rat io and blockage ratio.
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