233 research outputs found
Mechanically robust transparent anti-icing coatings: Roles of dispersion status of Titanate nanotubes
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Ice accretion on automobiles, aerospace components, precision instruments, and photovoltaic devices detrimentally affect their performance and increase the maintenance cost. Despite significant efforts devoted to the investigation of anti-icing coatings in the past decades, mechanically robust and transparent anti-icing coatings are rarely reported. In this study, titanate nanotubes are used as filler to prepare mechanically robust anti-icing coatings with a sol-gel method. Specially, the effect of dispersion status of nanotubes on the transmittance, surface roughness, and water repellency is investigated. The optimized smooth, transparent coating exhibits higher water repellency and better anti-icing performance in terms of ice-adhesion strength, icing delay time, and ice-nucleation temperature than the rough one. Much higher hardness and scratch resistance than that of commercially available icephobic or anti-icing coatings is obtained on the smooth, transparent sample; the coating also presents good adhesion to the substrate
Tunable nonlinear optical bistability based on Dirac semimetal in photonic crystal Fabry-Perot cavity
In this paper, we study the nonlinear optical bistability (OB) in a
symmetrical multilayer structure. This structure is constructed by embedding a
nonlinear three-dimensional Dirac semimetal (3D DSM) into a solution filled
one-dimensional photonic crystal Fabry-Perot cavity. OB stems from the third
order nonlinear conductivity of 3D DSM and the local field of resonance mode
could enhance the nonlinearity and reduce the thresholds of OB. This structure
achieves the tunability of OB due to that the transmittance could be modulated
by the Fermi energy. OB threshold and threshold width could be remarkably
reduced by increasing the Fermi energy. Besides, it is found that the OB curve
depends heavily on the angle of incidence of the incoming light, the structural
parameters of the Fabry-Perot cavity, and the position of 3D DSM inside the
cavity. After parameter optimization, we obtained OB with a threshold of 106
V/m. We believe this simple structure provides a reference idea for realizing
low threshold and tunable all optical switching devices. Keywords: Optical
bistability, Dirac semimetal, Fabry-Perot cavity
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Aphrodisiac Use Associated with HIV Infection in Elderly Male Clients of Low-Cost Commercial Sex Venues in Guangxi, China: A Matched Case-Control Study
Background: Rising HIV infection rates have been observed among elderly people in Guangxi, China. Inexpensive aphrodisiacs are available for purchase in suburban and rural areas. This study aims to investigate the association between aphrodisiac use and increased HIV risk for middle-aged and elderly men in Guangxi. Methods: A matched case-control study of aphrodisiac use-associated HIV infection was performed among male subjects over 50 years old who were clients of low-cost commercial sex venues in Guangxi. The cases were defined as clients who were HIV-positive and two controls were selected for each case. The cases and the controls were matched on the visited sex venue, age (±3 years), number of years of purchasing sex (±3 years), and educational attainment. Subjects were interviewed and tested for HIV. Paired t-test or McNemar Chi-squared test were used to compare the characteristics between the cases and controls. A stepwise conditional logistic regression was used to identify risk factors associated with HIV infection. Findings: This study enrolled 103 cases and 206 controls. Aphrodisiac use (P = 0.02, odds ratio (OR) = 1.81, 95% CI = 1.08–3.04), never using condom during commercial sex encounter (P = 0.03, odds ratio (OR) = 1.82, 95% CI = 1.08–3.07), and lacking a stable partner (P = 0.03, odds ratio (OR) = 1.76, 95% CI = 1.05–2.98) were found to be risk factors for HIV infection among the study groups. For subjects reporting aphrodisiac use, the frequency of purchasing sex was positively correlated with the frequency of aphrodisiac use (r = 0.3; p = 0.02). Conclusions: Aphrodisiac use was significantly associated with increased HIV infection risk in men over 50 years old who purchased commercial sex in the suburban and rural areas of Guangxi. Further research and interventions should address the links between aphrodisiac use, commercial sex work, condom use, and increased HIV transmission
Correlation between tibial valgus deformity and aspect ratio of resected tibial surface in female Chinese patients undergoing total knee arthroplasty
BackgroundMorphology of the resected tibial surface is the reference for tibial component design, selection, and implantation in total knee arthroplasty (TKA). This comparative study sought to answer whether valgus deformity of the tibia would affect the morphology of the resected tibial surface in TKA.MethodsThirty-one female Chinese patients with valgus tibias were retrospectively and consecutively identified from a single-center registration database. Thirty-one patients with well-aligned tibias were matched in terms of gender, height, and weight. Weight-bearing full-length radiographs and computed tomography images of the whole lower limb were obtained for every case. Tibial resection was mimicked perpendicular to the mechanical axis of the tibia in the frontal plane with 3° of posterior slope and a cut level individualized by the actual intraoperative cut. On the resected surface, mediolateral dimension (MLD), medial anteroposterior dimensions (mAPD), and lateral anteroposterior dimensions (lAPD) were measured, and aspect ratios (AR) were calculated. We compared the AR between the two groups.ResultsThe aspect ratio of resected tibial surface positively correlated with tibial valgus alignment. Patients with valgus tibias had significantly smaller AR (MLD/mAPD) for the medial plateau (1.50 ± 0.06 vs. 1.54 ± 0.07, P = 0.032). However, the AR for the lateral plateau was similar between the two groups (1.63 ± 0.08 vs. 1.65 ± 0.07, P = 0.328).ConclusionThis difference in morphology of resected tibial surface between valgus and well-aligned tibias should be considered in tibial component design, as well as in the selection and placement of TKA implants for knees with valgus tibias
Risk factors for cerebrovascular disease mortality among the elderly in Beijing: A competing risk analysis
Objective: To examine the associations of combined lifestyle factors and physical conditions with cerebrovascular diseases (CBVD) mortality, after accounting for competing risk events, including death from cardiovascular diseases, cancers and other diseases. Methods: Data on 2010 subjects aged over 55 years were finally analyzed using competing risk models. All the subjects were interviewed by the Beijing Longitudinal Study of Aging (BLSA), in China, between 1 January 1992 and 30 August 2009. Results: Elderly females were at a lower risk of death from CBVD than elderly males (HR = 0.639, 95% CI = 0.457-0.895). Increasing age (HR = 1.543, 95% CI = 1.013-2.349), poor self-rated health (HR = 1.652, 95% CI = 1.198-2.277), hypertension (HR = 2.201, 95% CI = 1.524-3.178) and overweight (HR = 1.473, 95% CI = 1.013-2.142) or obesity (HR = 1.711, 95% CI = 1.1754-2.490) was associated with higher CBVD mortality risk. Normal cognition function (HR = 0.650, 95% CI = 0.434-0.973) and living in urban (HR = 0.456, 95% CI = 0.286-0.727) was associated with lower CBVD mortality risk. Gray\u27s test also confirmed the cumulative incidence (CIF) of CBVD was lower in the \u27married\u27 group than those without spouse, and the mortality was lowest in the \u27nutrition sufficient\u27 group among the \u27frequent consumption of meat group\u27 and the \u27medial type group\u27 (P valu
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