Bismuth nanowire thermoelectrics Kim, Jeongmin; Shim, Wooyoung; Lee, Wooyoung
Journal of materials chemistry. C, Materials for optical and electronic devices,
01/2015, Letnik:
3, Številka:
46
Journal Article
Recenzirano
During the past 20 years, the thermoelectric properties of nanostructures such as one-dimensional bismuth (Bi) platforms have prompted the development of a wide variety of nanowire growth methods, ...aiming to achieve higher energy-conversion efficiency. Most of these methods have demonstrated single-crystal nanowire growth of a quality unmatched in bulk Bi. However, in contrast to the theoretical expectation that Bi nanowires should exhibit high thermoelectric performance, their observed thermoelectric properties have prevented their technological exploitation. Here, we review the current progress in the thermoelectrics of bismuth nanowires, the fundamentals of their advantage and limitation over bulk Bi, and their potential use for enhancing the thermoelectric performance.
Here, we review the current progress in the thermoelectrics of bismuth nanowires, the fundamentals of their advantage and limitation over bulk Bi, and their potential use for enhancing thermoelectric performance.
Disclosure of human immunodeficiency virus (HIV) infection status improves treatment adherence and HIV prevention. Social networks influence such disclosure by people living with HIV/AIDS (PLWH). ...This study aimed to investigate the disclosure status of Korean PLWH and determine the social network characteristics associated with disclosure. A cross-sectional study design was used, and 148 Korean PLWH answered self-report questionnaires that included items on the characteristics of social networks and disclosure. Logistic regression and decision tree analysis were performed. In total, 81 participants (54.7%) reported disclosing HIV status to the most important supporter. Five factors were found to influence disclosure: age, self-help group participation, living arrangement, social network relationship, and tie strength; three groups had higher percentages of nondisclosure. The findings suggest that healthcare practitioners should provide adequate counseling by considering the characteristics of social networks and disclosure status of PLWH. Researchers should identify high-risk populations using decision tree analysis.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
BACKGROUND:In this study, we examined the relationship between postoperative cognitive dysfunction (POCD) and intraoperative regional cerebral oxygen saturation (rSO2) in elderly patients undergoing ...spinal surgery.
METHODS:We enrolled 87 patients older than 65 years. All patients were tested using a battery of cognitive function tests (Korean Mini-Mental State Examination and visuomotor test of Dynamic Lowenstein Occupational Therapy Cognitive Assessment–Geriatric Version) the day before their surgical operation and on the seventh postoperative day. Our threshold for defining POCD for a given patient was a Reliable Change Index score of <−1.96 occurring on 2 tests.
RESULTS:POCD was detected in 20 patients (23%) at the seventh postoperative day. Between-patient baseline characteristics, surgical data, and baseline cognitive function were similar for both those who developed POCD and those who did not. A univariate analysis that included age, female sex, education level, presence of diabetes, and duration of intraoperative decline in rSO2 to a level of <60% of baseline revealed that only diabetes and duration of rSO2 <60% (odds ratio, 1.01; 95% confidence interval CI, 1.005–1.010) were found to be risk factors for POCD. After multivariate logistic regression analysis of these 2 variables, only the duration of rSO2 <60% (odds ratio, 1.006; 95% CI, 1.00–1.01, P = 0.014) remained as an independent risk factor for POCD. The area under the receiver operation characteristic of the duration of rSO2 <60% was 0.70 (95% CI, 0.57–0.82; P = 0.008). The optimal cutoff value was 157 minutes with a sensitivity of 75% and specificity of 72%.
CONCLUSIONS:This study showed that the duration of decline in rSO2 <60% during lumbar spinal surgery was correlated with the development of POCD at the seventh postoperative day in elderly patients.
Osteoarthritis (OA) is a progressive and irreversible degenerative joint disease that is characterized by cartilage destruction, osteophyte formation, subchondral bone remodeling, and synovitis. ...Despite affecting millions of patients, effective and safe disease-modifying osteoarthritis drugs are lacking. Here we reveal an unexpected role for the small molecule 5-aminosalicylic acid (5-ASA), which is used as an anti-inflammatory drug in ulcerative colitis. We show that 5-ASA competes with extracellular-matrix collagen-II to bind to osteoclast-associated receptor (OSCAR) on chondrocytes. Intra-articular 5-ASA injections ameliorate OA generated by surgery-induced medial-meniscus destabilization in male mice. Significantly, this effect is also observed when 5-ASA was administered well after OA onset. Moreover, mice with DMM-induced OA that are treated with 5-ASA at weeks 8-11 and sacrificed at week 12 have thicker cartilage than untreated mice that were sacrificed at week 8. Mechanistically, 5-ASA reverses OSCAR-mediated transcriptional repression of PPARγ in articular chondrocytes, thereby suppressing COX-2-related inflammation. It also improves chondrogenesis, strongly downregulates ECM catabolism, and promotes ECM anabolism. Our results suggest that 5-ASA could serve as a DMOAD.
Coronavirus disease 2019 (COVID-19) has been an epidemic in the Republic of Korea since the first patient who came in China was confirmed as having the disease on January 19, 2020. Therefore, surgery ...for COVID-19-related patients is expected to increase.
We experienced two cases of COVID-19-related patients who underwent surgery for femur fracture under general anesthesia. In one case, infection control to prevent transmission was achieved, while in the second case, healthcare workers were exposed to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).
In areas where there is COVID-19 epidemic, SARS-CoV-2 real-time polymerase chain reaction should be performed before surgery in patients with symptoms of respiratory infection such as fever, cough, and sputum, or for those in whom the possibility of COVID-19 cannot be completely excluded. Efforts should be made to prevent healthcare worker's exposure and the contamination of the operating room.
In order to prevent the harmful effects in water phase such as eutrophication, industrial and urban sewages must be treated before discharging into the aquatic environment. In this work, amine ...grafted magnetic nanoporous silica materials are synthesized and applied as an adsorbent for the recovery of nutrients from waste black water. The magnetic force could separate the surface func-tionalized nanoporous silica materials from aqueous medium after treatment, and showed the higher adsorption capacity of nutrients than that of the original mesoporous silica. The multi-functional nanoporous silica adsorbents were effectively removed phosphate and nitrate at 20 °C with the maximum adsorption capacities of 42.5 and 34.9 mg/g, respectively. The overall results indicated that the synthesized multi-functional nanoporous silica sorbents can be a candidate material for the nutrient recovery in wastewater treatment system.
The electrostatic discharge (ESD) phenomenon is a critical reliability concern, and the charged device model (CDM) is well known for its relatively high voltage peak with few nanoseconds duration on ...the gate oxide (GOX), resulting in breakdown. However, as ESD design window shrinks, even GOX degradation before hard breakdown during component-level CDM qualification can cause reliability issues such as soft-failures. This degradation can be attributed to the quickly increased electric field on the GOX, leading to the rapid creation of trapped charges before catastrophic damage. This study analyzes CDM-induced bias temperature instability (BTI)-like degradation and models threshold voltage (Vth) shift using a very-fast transmission line pulse (VF-TLP) with 1ns pulse width and 200ps rise and fall time, generally proposed for CDM evaluation. The experiment was conducted with various VF-TLP voltage peaks, numbers of pulsing iterations and GOX areas. And, finally, Vth shift model considering statistical variation is presented. This model can be a guideline to prevent CDM-induced GOX degradation at an early design stage.
Wetting of the liquid metal on the solid electrolyte of a liquid metal battery controls the operating temperature and performance of the battery. Liquid sodium electrodes are particularly attractive ...because of their low cost, natural abundance, and geological distribution. However, they wet poorly on a solid electrolyte near its melting temperature, limiting their widespread suitability for low-temperature batteries to be used for large-scale energy storage systems. Herein, we develop an isolated metal-island strategy that can improve sodium wetting in sodium-beta alumina batteries that allows operation at lower temperatures. Our results suggest that in situ heat treatment of a solid electrolyte followed by bismuth deposition effectively eliminates oxygen and moisture from the surface of the solid electrolyte, preventing the formation of an oxide layer on the liquid sodium, leading to enhanced wetting. We also show that employing isolated bismuth islands significantly improves cell performance, with cells retaining 94% of their charge after the initial cycle, an improvement over cells without bismuth islands. These results suggest that coating isolated metal islands is a promising and straightforward strategy for the development of low-temperature sodium-β alumina batteries.
In two-dimensional van der Waals crystals, the interlayer stacking sequence often leads to a change in crystal symmetry and, thus, new polymorphs, leading to an abundant array of physical properties. ...In this paper, we report the polymorphic form of 2H–3R–NbSe2 that exhibits a substantial difference in terms of the gate dependence of semimetallic behavior and Seebeck coefficient, compared to the well-known 2H–NbSe2 with metallic transport behavior. The semimetallic features of 2H–3R–NbSe2 indicate the presence of minor carriers, confirmed through theoretical calculations, which is in good agreement with the transport behavior. Our results reveal perspectives for understanding the metastable 2H–3R phase NbSe2, which is not far from equilibrium, and for engineering the materials necessary for efficient energy harvesting.
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•Stacking-dependent crystal structures and transport properties of two polymorphs, 2H- and 2H–3R–NbSe2 were investigated.•Stacking sequence and atomic arrangement of 2H- and 2H–3R–NbSe2 were clearly observed by HR-STEM.•Thermoelectric transport characterization and theoretical calculation revealed the semimetallic feature of 2H–3R phase NbSe2.
In this paper, we address a two-stage hybrid flowshop scheduling problem with identical parallel machines in each stage. The problem assumes that the queue (Q)-time for each job, which represents the ...waiting time to be processed in the current stage, must be limited to a predetermined threshold due to quality concerns for the final product. This problem is motivated by one that occurs in the real field, especially in the diffusion workstation of a semiconductor fabrication. Our objective is to minimize the makespan of the jobs while considering product quality. To achieve this goal, we formulated mathematical programming, developed two dominance properties for this problem, and proposed three heuristics with the suggested dominance properties to solve the considered problem. We conducted simulation experiments to evaluate the performance of the proposed approaches using randomly generated problem instances that are created to closely resemble real production scenarios, and the results demonstrate their superiority over existing methods. Furthermore, we applied the proposed methods in a real-world setting within the semiconductor fabrication industry, where they have exhibited better performance compared to the dispatching rules commonly used in practical applications. These findings validate the effectiveness and applicability of our proposed methodologies in real-world scenarios.
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