Field-driven dynamics of nematic microcapillaries

Polymer-dispersed liquid crystal (PDLC) composites have long been a focus of study for their unique electro-optical properties which have resulted in various applications such as switchable (transparent/translucent) windows. These composites are manufactured using desirable "bottom-up" techniques, such as phase separation of a liquid crystal/polymer mixture, which enable production of PDLC films at very large scales. LC domains within PDLCs are typically spheroidal, as opposed to rectangular for an LCD panel, and thus exhibit substantially different behaviour in the presence of an external field. The fundamental difference between spheroidal and rectangular nematic domains is that the former results in the presence of nanoscale orientational defects in LC order while the latter does not. Progress in the development and optimization of PDLC electro-optical properties has progressed at a relatively slow pace due to this increased complexity. In this work, continuum simulations are performed in order to capture the complex formation and electric field-driven switching dynamics of approximations of PDLC domains. Using a simplified elliptic cylinder (microcapillary) geometry as an approximation of spheroidal PDLC domains, the effects of geometry (aspect ratio), surface anchoring, and external field strength are studied through the use of the Landau--de Gennes model of the nematic LC phase.Comment: 22 pages, 9 figures, Physical Review

Geometry and Anchoring Effects on Elliptic Cylinder Domains of Nematic Phases

Compounds which exhibit liquid crystal phases have been widely used in display technology. The majority of display applications utilize the nematic liquid crystal phase, which is a liquid-like phase which has partial orientational order at the molecular level. The nematic phase exhibits birifringence which can be manipulated through the application of an external field. Subsequently, all liquid crystal-based display technology utilizes the application of an external field to “switch” or tune the optical properties of a nematic domain into a desired optical state. In addition to an external field, the geometry and surface interactions of the liquid crystal domain must be precisely controlled in order for the display to operate properly. Liquid crystal displays (LCDs) utilize a rectangular domain, or pixel, within which the nematic domain is exposed to surface anchoring conditions that result in a twist of the nematic alignment through the thickness of the domain. In this work, a different type of liquid crystal domain that is elliptic is studied which is formed through “bottom-up” techniques, such as phase separation of a liquid crystal/polymer mixture to form a polymer-dispersed liquid crystal (PDLC) composite. Nematic domains within PDLCs are spheroidal, as opposed to rectangular for a pixel, and thus exhibit substantially different behaviour in the presence of an external field. The fundamental difference between spheroidal and rectangular nematic domains is that the former requires the presence of defects in nematic order while the latter does not. The overall objective of this work is to study, for a simplified elliptic cylinder domain, the formation of the nematic domain, the resulting domain texture in the presence of an external field, and the domain texture following release of the external field. These three states are directly related to applications of PDLC films as optical functional materials, where an external (electric) field is used to manipulate the optical properties of the film. The effects of geometry (aspect ratio), surface anchoring, and external field strength are studied through a simulation-based approach using the Landau-de Gennes theory of the nematic phase

Ataxia Oculomotor Apraxia Type 1 in the Siblings of a Family: A Novel Mutation

How to Cite This Article: Karimzadeh P, khayatzadeh kakhki S,Esmail Nejad Sh. S., Houshmand M,Ghofrani M. Ataxia oculomotor apraxia 1 in two siblings of a family:a novel mutation. Iran J Child Neurol.Winter 2017; 11(1):78-81.AbstractAlthough AOA1 (ataxia oculomotor apraxia1) is one of the most common causes of autosomal recessive cerebellar ataxias in Japanese population, it is reported from all over the world. The clinical manifestations are similar to ataxia telangiectasia in which non-neurological manifestations are absent and include almost 10% of autosomal recessive cerebellar ataxias. Dysarthria and gait disorder are the most two common and typical manifestations. Oculomotor apraxia is usually seen a few years after the manifestations start. APTX gene on 9p13.3 chromosome is expressed in the cells of all human body tissues and different mutations had been discovered. Here we report two siblings (a girl and a boy) of consanguineous parents visited at Mofid Pediatrics Hospital in 2015, with history of gait ataxia, titubation, tremor, and oculomotor apraxia around five yr old and after that. The brother showed symptoms of disease earlier and more severe than his sister did. After ruling out the common etiologies of progressive ataxia, we did genetic study for AOA1 that showed a homozygous frameshift mutation as c.418_418 del was found. This mutation was not reported before so this was a new mutation in APTX gene.References1. Jafar-Nejad P, Maririch SM, Zoghbi HM .The cerebellum and hereditary ataxias. In: Swaiman KF, Ashwal S, Ferriero DM, Schor NF. Swaiman’s Pediatric Neurology Principles, and Practice.15th ed. 2012.P.939-952.2. Pina-Garza JE. Ataxias. In:Pina-Garza JE. Fenichel Clinical pediatric neurology. 7th ed. 2013.P.215-231.3. Le Ber I, Moreira MC, Rivaud-Péchoux S, Chamayou C, Ochsner F, Kuntzer T, et al. Cerebellar ataxia with oculomotor apraxia type 1: clinical and genetic studies. Brain 2003; 126:2761-72.4. Coutinho P, Barbot C. Ataxia with Oculomotor Apraxia Type 1. 2002 Jun 11 [Updated 2015 Mar 19]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: https:// www.ncbi.nlm.nih.gov/books/NBK1456/5. Shahwan A, Byrd PJ, Taylor AM, Nestor T, Ryan S, King MD. Atypical presentation of ataxia-oculomotor apraxia type 1. Dev Med Child Neurol 2006 Jun; 48(6):529-32. 6. Shimazaki H, Takiyama Y, Sakoe K, Ikeguchi K, Niijima K, et al. Early-onset ataxia with ocular motor apraxia and hypoalbuminemia: the aprataxin gene mutations. Neurology 2002; 59(4):590-5.7. Yokoseki A, Ishihara T, Koyama A, Shiga A, Yamada M, Suzuki C,and et al. Genotype-phenotype correlations in early onset ataxia with ocular motor apraxia and hypoalbuminaemia. Brain 2011; 134:1387-99.8. Moreira MC, Barbot C, Tachi N, Kozuka N, Mendonça P, Barros J, Coutinho P, Sequeiros J, Koenig M. Homozygosity mapping of Portuguese and Japanese forms of ataxia-oculomotor apraxia to 9p13, and evidence for genetic heterogeneity. Am J Hum Genet 2001; 68(2):501-8

Micronutrients and Infection with COVID-19: A Critical Mini-Review

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has been the cause of a global pandemic. Given the impact of nutritional status upon immune function, it is crucial to understand the relationship between micronutrient intake and severity of the disease. This mini-review aimed to summarize the known associations between specific micronutrients (vitamin A, D, E, C and zinc, selenium and magnesium) and the health of coronavirus-infected patients. Low serum levels of these micronutrients are associated with the incidence and severity of SARS-CoV-2. However, further studies are needed to evaluate the outcomes of supplementation with these nutrients

Dietary behaviors in relation to prevalence of irritable bowel syndrome in adolescent girls.

BACKGROUNDS AND AIMS There is limited evidence regarding the relationship between dietary behaviors and irritable bowel syndrome (IBS). This study aimed to explore the association between diet-related practices and prevalence of IBS. METHODS The study was conducted among 988 adolescent girls living in Iran. Dietary behaviors were pre-defined and assessed in nine domains using a pre-tested questionnaire. To investigate the association between diet-related practices and the presence of IBS, we used logistic regression analysis in crude and adjusted models. RESULTS The prevalence of IBS was 16.9% in this population. Compared with individuals who did not consume fluid with their meal, those who always consumed fluid with meals had a greater chance of IBS (OR: 2.91; P: 0.01). We found a direct relationship between a greater intake of spicy food and IBS prevalence (OR: 5.28; P: 0.02). The individuals who ate fried foods every day also had a greater risk of IBS compared with those who did not consume fried foods (OR: 1.65; P: 0.01). The subjects who had lost ≥5 teeth had 2.23 times greater odds for IBS than the individual who had lost ≤1 tooth (OR: 2.23; P: 0.01) was a significant inverse relationship between the chewing sufficiency and the risk of IBS (OR: 4.04; P: 0.02). These associations remained significant after controlling for potential confounder CONCLUSIONS: Intra-meal fluid intake, chewing insufficiency, higher tooth loss and the consumption of spicy and fried food were associated with increased risk of IBS. Prospective studies are needed to confirm these findings

Serum high sensitive C reactive protein is associated with dietary intakes in diabetic patients with and without hypertension: a cross-sectional study

Background: Serum C reactive protein (CRP) concentrations independently predict the development of diabetes, metabolic syndrome and cardiovascular disease. However, the impact of dietary factors on serum CRP concentrations in diabetic patients has received limited attention. We aimed to investigate the association between dietary factors and serum CRP, measured using a high sensitivity (hs-)assay, among diabetic patients with and without hypertension and healthy subjects. Methods: In this cross-sectional study, diabetics with (n=325) and without hypertension (n=599) and healthy individuals (n=1220) were recruited in Mashhad, Iran. Dietary intake was assessed by 24-hour recall. Biochemical parameters including serum hs-CRP were measured using standard protocols. Stepwise multiple regression analysis was used to predict whether serum hs-CRP concentration was associated with dietary constituents. Results: hs-CRP was significantly higher among hypertensive and non-hypertensive diabetic patients compared to healthy subjects (p<0.001). The dietary intake of zinc +6.4% and calcium -3.4%, and BMI +3.9% explained approximately 13.7% of the variation in serum hs-CRP among diabetic hypertensive patients. Approximately, 9.7% of the variation in serum hs-CRP in diabetic non-hypertensive patients could be explained by BMI, and intake of sodium, iron and cholesterol. In the healthy subjects approximately 4.4% of the total variation in serum hs-CRP concentration could be explained by cholesterol consumption and waist circumference. Conclusion: Serum hs-CRP concentrations were found to be a significant predictor for hypertensive and non-hypertensive diabetic subjects. There was a significant association between dietary factors include zinc, iron, sodium and cholesterol and serum hs-CRP whilst there was an inverse association between dietary calcium and serum hs-CRP in diabetic hypertensive individuals

The impact of microbial composition on postprandial glycaemia and lipidaemia: A systematic review of current evidence

Postprandial hyperglycaemia is associated with increased risk of cardiovascular disease. Recent studies highlight the role of the gut microbiome in influencing postprandial glycaemic (PPG) and lipidaemic (PPL) responses. The authors of this review sought to address the question: “To what extent does individual gut microbiome diversity and composition contribute to PPG and PPL responses?” CINAHL Plus, PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched from January 2010 to June 2020. Following screening, 22 studies were eligible to be included in the current review. All trials reported analysis of gut microbiome diversity and composition and PPG and/or PPL. Results were reported according to the ‘Preferred Reporting Items for Systematic Reviews and Meta-Analysis’ (PRISMA) statement. Individual microbiota structure was found to play a key role in determining postprandial metabolic responses in adults and is attributed to a complex interplay of diet, microbiota composition, and metagenomic activity, which may be predicted by metagenomic analysis. Alterations of gut microbiota, namely relative abundance of bacterial phylum Actinobacteria and Proteobacteria, along with Enterobacteriaceae, were associated with individual variation in postprandial glycaemic response in adults. The findings of the current review present new evidence to support a personalised approach to nutritional recommendations and guidance for optimal health, management, and treatment of common metabolic disorders. In conclusion, personalised nutrition approaches based on individual microbial composition may improve postprandial regulation of glucose and lipids, providing a potential strategy to ameliorate cardiometabolic health outcomes

The Association between Ultra-Processed Foods, Quality of Life and Insomnia among Adolescent Girls in Northeastern Iran

Ultra-processed foods have been associated with increased risk of chronic disease, poor overall health and psychological outcomes. This study explored the association of ultra-processed foods with quality of life in adolescent girls from northeastern Iran. In an interdisciplinary cross-sectional study, n = 733 adolescent girls were recruited by random cluster sampling. Assessments were completed for demographics, physical activity, anthropometric and biochemical parameters, psychological health and dietary intake. The participants were categorized into quartiles of ultra-processed food intake, and multivariable logistic regression was used in several models to investigate the association between ultra-processed food intake and psychological health. The mean age of the participants was 14 years. There were no significant differences in participant demographics for the quartiles of ultra-processed food intake including weight, waist–hip ratio, waist circumference, depression, insomnia and cardiometabolic markers related to cardiovascular disease risk. Adjusted logistic regression showed participants in the highest category of ultra-processed food consumption had an increased likelihood of reduced quality of life (OR: 1.87, 95% CI: 1.13–3.11), with a greater chance for insomnia (OR: 4.04, 95% CI: 1.83–8.94) across all models. However, no significant associations were observed between consumption of ultra-processed foods and daytime sleepiness. We highlight the association between ultra-processed food consumption and poor quality of life and insomnia amongst adolescent girls. Large longitudinal integrated public health studies in different ethnicities are needed to confirm these associations and evaluate their possible impact for optimizing health promotion programs

High-dose vitamin D supplementation is associated with an improvement in several cardio-metabolic risk factors in adolescent girls: a nine-week follow up study

Background: Vitamin D deficiency is a prevalent and important global health problem. Because of its role in growth and development, vitamin D status is likely to be particularly important in adolescent girls. Here we explored the effects of high-dose vitamin D supplementation on cardiometabolic risk factors. Methods: We have examined the effects of vitamin D supplementation on cardio-metabolic risk factors in 988 healthy adolescent girls in Iran. Fasting blood samples and anthropometric measurements were obtained at baseline and after supplementation with high dose vitamin D. All individuals took a capsule of 50000 IU vitamin D/ week for nine weeks. The study was completed by 940 participants. Results: the prevalence of vitamin D deficiency was 90% at baseline, reducing to16.3% after vitamin D supplementation. Vitamin supplementation was associated with a significant increase in serum levels of 25 (OH) vitamin D and calcium. There were significant reductions in diastolic blood pressure, heart rate, waist circumference, and serum fasting blood glucose, total- and low density lipoprotein-cholesterol after the nine-week period on vitamin D treatment, but no significant effects were observed on body mass index, systolic blood pressure, or serum high density lipoprotein-cholesterol and triglyceride. Conclusion: vitamin D supplementation had beneficial effects on cardio-metabolic profile in adolescent girls