All-optical switching using a new photonic crystal directional coupler

In this paper all-optical switching in a new photonic crystal directional coupler is performed.  The structure of the switch consists of a directional coupler and a separate path for a control signal called “control waveguide”. In contrast to the former reported structures in which the directional couplers are made by removing a row of rods entirely, the directional coupler in our optical switch is constructed by two reduced-radius line-defect waveguides separated by the control waveguide. Furthermore, in our case the background material has the nonlinear Kerr property. Therefore, in the structure of this work, no frequency overlap occurs between the control waveguide mode and the directional coupler modes. It is shown that such a condition provides a very good isolation between the control and the probe signals at the output ports. In the control waveguide, nonlinear Kerr effect causes the required refractive index change by the presence of a high power control (pump) signal. Even and odd modes of the coupler are investigated by applying the distribution of the refractive index change in the nonlinear region of a super-cell so that a switching length of about 94 µm is obtained at the wavelength of 1.55 µm. Finally, all-optical switching of the 1.55 µm probe signal using a control signal at the wavelength of 1.3 µm, is simulated through the finite-difference time-domain method, where both signals are desirable in optical communication systems. A very high extinction ratio of 67 dB is achieved and the temporal characteristics of the switch are demonstrated

Investigations and Simulations of All optical Switches in linear state Based on Photonic Crystal Directional Coupler

Switching is a principle process in digital computers and signal processing systems. The growth of optical signal processing systems, draws particular attention to design of ultra-fast optical switches. In this paper, All Optical Switches in linear state Based On photonic crystal Directional coupler is analyzed and simulated. Among different methods, the finite difference time domain method (FDTD) is a preferable method and is used. We have studied the application of photonic crystal lattices, the physics of optical switching and photonic crystal Directional coupler. In this paper, Electric field intensity and the power output that are two factors to improve the switching performance and the device efficiency are investigated and simulated. All simulations are performed by COMSOL software

Investigations and Simulations of All optical Switches in linear state Based on Photonic Crystal Directional Coupler

Switching is a principle process in digital computers and signal processing systems. The growth of optical signal processing systems, draws particular attention to design of ultra-fast optical switches. In this paper, All Optical Switches in linear state Based On photonic crystal Directional coupler is analyzed and simulated. Among different methods, the finite difference time domain method (FDTD) is a preferable method and is used. We have studied the application of photonic crystal lattices, the physics of optical switching and photonic crystal Directional coupler. In this paper, Electric field intensity and the power output that are two factors to improve the switching performance and the device efficiency are investigated and simulated. All simulations are performed by COMSOL software

All-optical switching using a new photonic crystal directional coupler

In this paper all-optical switching in a new photonic crystal directional coupler is performed.  The structure of the switch consists of a directional coupler and a separate path for a control signal called “control waveguide”. In contrast to the former reported structures in which the directional couplers are made by removing a row of rods entirely, the directional coupler in our optical switch is constructed by two reduced-radius line-defect waveguides separated by the control waveguide. Furthermore, in our case the background material has the nonlinear Kerr property. Therefore, in the structure of this work, no frequency overlap occurs between the control waveguide mode and the directional coupler modes. It is shown that such a condition provides a very good isolation between the control and the probe signals at the output ports. In the control waveguide, nonlinear Kerr effect causes the required refractive index change by the presence of a high power control (pump) signal. Even and odd modes of the coupler are investigated by applying the distribution of the refractive index change in the nonlinear region of a super-cell so that a switching length of about 94 µm is obtained at the wavelength of 1.55 µm. Finally, all-optical switching of the 1.55 µm probe signal using a control signal at the wavelength of 1.3 µm, is simulated through the finite-difference time-domain method, where both signals are desirable in optical communication systems. A very high extinction ratio of 67 dB is achieved and the temporal characteristics of the switch are demonstrated

The effects of curcumin on weight loss among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized controlled trials

Background and objective: The current systematic review and meta-analysis of randomized controlled trials (RCTs) was carried out to assess the influence of curcumin intake on weight among patients with metabolic syndrome and related disorders. Methods: We searched the following databases up until January 2018: MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials. The relevant data were extracted and evaluated for quality of the studies in accordance with the Cochrane risk of bias tool. Data were pooled using the inverse variance method and expressed as standardized mean difference (SMD) with 95 confidence intervals (95 CI). Results: Eighteen articles (21 studies) that comprised a total of 1,604 individuals were finally included in the meta-analysis. Curcumin intake significantly reduced body mass index (BMI) (SMD �0.37; 95 CI, �0.61, �0.13; P < 0.01), weight (SMD �0.23; 95 CI, �0.39, �0.06; P < 0.01), waist-circumference (WC) (SMD �0.25; 95 CI, �0.44, �0.05; P = 0.01), leptin levels (SMD �0.97; 95 CI, �1.18, �0.75; P < 0.001) and increased adiponectin levels (SMD 1.05; 95 CI, 0.23, 1.87; P = 0.01). We found no significant effect of curcumin intake on hip ratio (HR) (SMD �0.17; 95 CI, �0.42, 0.08; P = 0.18). Conclusions: Overall, we have found that curcumin intake among patients with metabolic syndrome and related disorders was correlated with a significant reduction in BMI, weight, WC, and leptin, and a significant increase in adiponectin levels, but did not affect HR. Copyright © 2019 Akbari, Lankarani, Tabrizi, Ghayour-Mobarhan, Peymani, Ferns, Ghaderi and Asemi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms

Electrospun Nano-fibers for biomedical and tissue engineering applications: A comprehensive review

Pharmaceutical nano-fibers have attracted widespread attention fromresearchers for reasons such as adaptability of the electro-spinning process and ease of production. As a flexible method for fabricating nano-fibers, electro-spinning is extensively used. An electro-spinning unit is composed of a pump or syringe, a high voltage current supplier, a metal plate collector and a spinneret. Optimization of the attained nano-fibers is undertaken through manipulation of the variables of the process and formulation, including concentration, viscosity, molecular mass, and physical phenomenon, as well as the environmental parameters including temperature and humidity. The nano-fibers achieved by electro-spinning can be utilized for drug loading. The mixing of two or more medicines can be performed via electro-spinning. Facilitation or inhibition of the burst release of a drug can be achieved by the use of the electro-spinning approach. This potential is anticipated to facilitate progression in applications of drug release modification and tissue engineering (TE). The present review aims to focus on electro-spinning, optimization parameters, pharmacological applications, biological characteristics, and in vivo analyses of the electro-spun nano-fibers. Furthermore, current developments and upcoming investigation directions are outlined for the advancement of electro-spun nano-fibers for TE. Moreover, the possible applications, complications and future developments of these nano-fibers are summarized in detail. © 2020 by the authors

The effects of vitamin D supplementation on expanded disability status scale in people with multiple sclerosis: A critical, systematic review and metaanalysis of randomized controlled trials

In this meta-analysis of randomized controlled trials (RCTs), the effects of vitamin D supplementation on the scores for the expanded disability status scale (EDSS) in people with multiple sclerosis (MS) are assessed. The following databases were search up to January 2018: MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials. The quality of the relevant extracted data was assessed according to the Cochrane risk of bias tool. Data were pooled by the use of the inverse variance method and expressed as mean difference with 95 Confidence Intervals (95 CI). Six studies were included in this meta-analysis. The findings demonstrated that supplementation with vitamin D alone and vitamin D plus calcium did not affect the EDSS score (WMD -0.11 (-0.33, 0.11); P = 0.32). In addition, subgroup analysis showed that vitamin D supplementation alone, when compared to the use of a placebo, and vitamin D plus calcium supplementation compared with the control did not affect EDSS (WMD -0.13 (-0.30, 0.11); P = 0.29) and (WMD -0.08 (-0.57, 0.41); P = 0.29), respectively. Overall, this meta-analysis indicated that taking vitamin D in people with MS had no significant effect on EDSS. © 2019 Elsevier B.V

Passive smoking is associated with cognitive and emotional impairment in adolescent girls

It is well established that smoking is associated with impaired mental health and sleep problems. However, the possible effects of passive smoking on cognitive and emotional characteristics have not previously been evaluated in adolescents. We investigated the association between passive smoking and cognitive and emotional function, and sleep patterns in 940 adolescent girls. The girls were divided into 2 groups [305 exposed subjects and 635 non-exposed subjects (the controls)]. The passive smokers had a significantly lower cognitive function and higher depression, aggression, and insomnia scores compared to the control group (P <0.05). No significant difference was detected with respect to day-time sleepiness and sleep apnea. Logistic regression analyses showed that the passive smokers were more likely than the controls to have cognitive impairments, depressive mood, aggressive behavior and insomnia. Adolescent passive smokers had significant differences in their cognitive abilities and emotional function