Experimental, Theoretical and Numerical Evaluation of Wicking Models for Liquid Imbibition in Dry Porous Wicks

Nowadays commercial wicks are utilized by consumer product companies in several important commercial applications including Tiki® Brand torches, the passive lubricants of machine gears, propellant management device, and fragrance dispersion units. Spontaneous imbibition of a liquid into porous wicks, also called wicking, is modeled using the single-phase Darcy’s law after assuming a sharp flow-front marked by full saturation behind the front. An analytical expression for the height of the wicking flow-front as a function of time is tested through comprehensive experiments using different wicks and an oil as the wicking liquid. We proposed a model based on sharp liquid-front where a good match with the experimental data was achieved. However, the proposed model based on the sharp liquid-front fails to account for partial saturation in the wicks. As a result, we applied the Richards equation to predict partial liquid saturations in wicks where the equation is solved numerically in 2-D using COMSOL and analytically in 1-D using Mathematica for glass-fiber wicks after treating them as transversely-isotropic porous media. As a novel contribution, the relative permeability and capillary pressure are determined directly from pore-scale simulations in wick microstructure using the state-of-the-art software GeoDict. The saturation along the wick length is determined experimentally through a new liquid-N2 based freezing technique. After including the gravity effect, good agreements between the numerical/analytical predictions and experimental results are achieved in saturation distributions. We also validated the Richards equation-based model while predicting absorbed liquid-mass into the wick as a function of time. A series of wicking experiments with wicks procured from our industrial partners were conducted where the use of a dyed liquid revealed essentially three types of macroscopic (visual) fronts—sharp, semi-sharp, and diffuse. The particulate wicks (i.e. the wicks formed by sintering polymer beads) invariably formed sharp fronts, while the fibrous wicks (i.e. wicks formed from fibers) formed either semi-sharp or diffuse fronts. The porosity was also found to play a role—the lower-porosity fibrous wicks displayed semi-sharp fronts, while the higher-porosity fibrous wicks caused the fronts to be diffuse. A study of SEM (Scanning Electron Microscopy) micrographs revealed that the latter behavior was caused by clustering of fibers thus leading to the formation of an inhomogeneous porous medium (perhaps promoting finger formation on micro-fronts). The experiments also revealed that the visually-observed fronts, for most parts, achieved a good match with the fronts estimated through the sharp-front mass gain formula. (Such a match was found to be lacking in the fibrous wicks displaying diffuse fronts.) We also investigated two parameters of interest to the users of wicks: 1) steady-state (SS) height reached by the visual front at very large times, 2) the liquid supply rate when the front is near the top. The parameters estimated using our sharp-front model matched well with the experimentally-observed ones. Finally, we conducted a CFD simulation using FLUENT where the flow of wicking liquid through a 2D microstructure made of ellipses of varying aspect ratio was modeled. A series of microstructures were created by varying the ellipse aspect ratio from 1:1 (20*20 µm) to 1:64 (20*1280 µm), with lower values representing particulate porous media and the higher values representing fibrous porous media. To study the effect of porosity, two values of 50% and 70% were considered. The flow simulation in particulate porous media produced somewhat even micro-fronts that indicate a flat visual (macroscopic) front. On the other hand, simulations in fibrous porous media produced highly uneven micro-fronts that point to a semi-sharp or diffuse visual fronts. Increasing the porosity results in clustering of solid phase and leads to further increase in the unevenness of micro-fronts, thus pointing to purely diffuse visual fronts. The evolution of saturation plots along the flow direction, obtained using a grid superimposed on fluid distribution pictures, was also studied and the predictions matched our previous experimental and numerical observations, i.e., particulate media create sharp fronts while fibrous media create diffuse fronts

RNA interference is not involved in natural antisense mediated regulation of gene expression in mammals

BACKGROUND: Antisense transcription, yielding both coding and non-coding RNA, is a widespread phenomenon in mammals. The mechanism by which natural antisense transcripts (NAT) may regulate gene expression are largely unknown. The aim of the present study was to explore the mechanism of reciprocal sense-antisense (S-AS) regulation by studying the effects of a coding and non-coding NAT on corresponding gene expression, and to investigate the possible involvement of endogenous RNA interference (RNAi) in S-AS interactions. RESULTS: We have examined the mechanism of S-AS RNA base pairing, using thymidylate synthase and hypoxia inducible factor-1α as primary examples of endogenous genes with coding and non-coding NAT partners, respectively. Here we provide direct evidence against S-AS RNA duplex formation in the cytoplasm of human cells and subsequent activation of RNAi. CONCLUSION: Collectively, our data demonstrate that NAT regulation of gene expression occurs through a pathway independent of Dicer associated RNAi. Moreover, we introduce an experimental strategy with utility for the functional examination of other S-AS pair interactions

Optical Coherence Tomographic Findings in Highly Myopic Eyes

Optical coherence tomography (OCT) has enhanced our understanding of changes in different ocular layers when axial myopia progresses and the globe is stretched. These findings consist of dehiscence of retinal layers known as retinoschisis, paravascular inner retinal cleavage, cysts and lamellar holes, peripapillary intrachoroidal cavitation, tractional internal limiting membrane detachment, macular holes (lamellar and full thickness), posterior retinal detachment, and choroidal neovascular membranes. In this review, recent observations regarding retinal changes in highly myopic eyes explored by OCT are described to highlight structural findings that cannot be diagnosed by simple ophthalmoscopy

Evaluation of alveolar basement membrane function in the diabetes mellitus patients

چکیده: زمینه و هدف: افزایش ضخامت غشاء پایه آلوئولی در مبتلایان دیابت تیپ یک و دو همراه با درگیری عروق کوچک ریه در آتوپسی‌ها گزارش شده است. برای ارزیابی فونکسیون غشاء پایه آلوئولی از اندازه گیری ظرفیت انتقال گاز منواکسید کربن در ریه استفاده می‌شود. هدف این مطالعه بررسی ظرفیت انتشار منواکسید کربن ریه در بیماران مبتلا به دیابت می باشد. روش بررسی: در یک مطالعه توصیفی - تحلیلی ظرفیت انتشار منواکسید کربن ریه در 70 (55 زن و 15 مرد) بیمار مبتلا به دیابت بدون سابقه بیماری قلبی، ریوی، کلیوی، کم خونی و بدون شکایت از علایم تنفسی اندازه گیری شد. 55 زن و 15 مرد سالم با خصوصیات مشابه بیماران برای گروه کنترل انتخاب شدند. در گروه بیماران و کنترل که اسپیرومتری طبیعی داشتند. ظرفیت انتشار منواکسید کربن ریه بصورت متد یکبار تنفس انجام شد. داده ها با استفاده از آزمون آماری t-student تجزیه و تحلیل شد. یافته ها: میزان متوسط ظرفیت انتشار منواکسید کربن ریه در بیماران مبتلا به دیابت بدون علایم تنفسی و گروه کنترل به ترتیب 4/2±65/9 و 79/1±10/9 میلی مول بر دقیقه بر کیلو پاسکال بود (05/0P>). همچنین میزان ظرفیت اصلاح شده حجمی تبادل منواکسید کربن در ریه نسبت به گروه کنترل تفاوت معنی‌دار نداشت. نتیجه گیری: این مطالعه نشان دهنده عدم کاهش ظرفیت انتشار منواکسید کربن در ریه در بیماران دیابتی بدون علایم تنفسی است که نشان دهنده سلامت بستر آلوئول و کاپیلرهای ریه ای می باشد. با استناد به این مطالعه به نظر می رسد انسولین استنشاقی در بیماران دیابتی بدون عوارض عروقی بخوبی جذب شود

Anticonvulsant and Antioxidant Effects of Pitavastatin Against Pentylenetetrazol-Induced Kindling in Mice

Purpose: The pleiotropic effects of statins (antioxidant and anti-inflammation) have been reported by previous studies. Therefore, we aimed to determine whether pitavastatin has protective effects against pentylenetetrazol (PTZ)-induced kindling in mice and also whether pitavastatin improves the brain antioxidant capacity and attenuates the oxidative injuries in kindled mice. Methods: Twenty-four mice were randomly divided into four groups (each group n=6); control, PTZ-kindling and PTZ-kindled rats treated with pitavastatin (1&4 mg/kg). PTZ kindling seizures were induced by repetitive intraperitoneal injections of PTZ (65 mg/kg) every 48 hours till day twenty-one. Animals received daily oral pitavastatin for twenty-one days. Latency, score and duration of the seizures were recorded. The activities of catalase (CAT) ad superoxide dismutase (SOD), and likewise the contents of malondialdehyde (MDA) and nitrate were assessed in the brains of all rats. Results: There was a progressive reduction in latency of the kindled rats in the next injections of PTZ. Pitavastatin reduced this value (latency) particularly at higher dose. Seizures duration and score also decreased in treatment groups. SOD and CAT activities significantly decreased in PTZ-kindling group by 62% and 64%, respectively, but pitavastatin did not significantly change the SOD and CAT activities. Brain MDA and nitrate significantly increased in PTZ-kindling group by 53% and 30%, respectively. Pitavastatin at higher dose significantly decreased the MDA and nitrate contents of PTZ-kindling rats by 45% and 32%, respectively. Conclusion: Our findings revealed that pitavastatin can improve the behavioral expression of the PTZ-kindling rats and attenuate the seizure-induced oxidative/nitrosative damage

Suppression of axial-torsional vibrations of a distributed drilling system by the eigenvector contradiction method

This article proposes an active control strategy to suppress self-excited coupled axial-torsional vibrations of a distributed drill-string system while the coupling takes place through the bit-rock interaction. The drill-string model is expressed as Neutral-type Delay Differential Equations (NDDEs) with constant and state-dependent state delays and constant input delays. As a first step in the novel controller design, an implementable input transformation is introduced, resulting in the elimination of the neutral terms from the equations of motion. This supports a simplified next step of stabilizing controller design. In the second step, a new analytic method named the “Eigenvector Contradiction Method” is proposed to provide sufficient conditions to ensure that all eigenvalues have real parts less than a prescribed value. Based on this criterion, an automated parametric feedback control law is designed. A case study simulation is presented to illustrate the effectiveness of the proposed control strategy.</p

Association between rs2303861 polymorphism in CD82 gene and nonalcoholic fatty liver disease: a preliminary case-control study

Aim To investigate the genetic factors involved in the development of non-alcoholic fatty liver disease (NAFLD) and its sequelae in a Middle Eastern population. Methods This genetic case-control association study, conducted in 2018, enrolled 30 patients with NAFLD and 30 control individuals matched for age, sex, and body mass index. After quality control measures, entire exonic regions of 3654 genes associated with human diseases were sequenced. Allelic association test and enrichment analysis of the significant genetic variants were performed. Results The association analysis was conducted on 27 NAFLD patients and 28 controls. When Bonferroni correction was applied, NAFLD was significantly associated with rs2303861, a variant located in the CD82 gene (P = 2.49 × 10−7, adjusted P = 0.0059). When we used Benjamini- Hochberg adjustment for correction, NAFLD was significantly associated with six more variants. Enrichment analysis of the genes corresponding to all the seven variants showed significant enrichment for miR-193b-5p (P = 0.00004, adjusted P = 0.00922). Conclusion A variant on CD82 gene and a miR-193b expression dysregulation may have a role in the development and progression of NAFLD and its sequela

Biclique cryptanalysis of MIBS-80 and PRESENT-80

In this paper we present the first biclique cryptanalysis of MIBS block cipher and a new biclique cryptanalysis of PRESENT block cipher. These attacks are performed on full-round MIBS-80 and full-round PRESENT-80. Attack on MIBS- 80 uses matching without matrix method and has a data complexity upper bounded by $2^{52}$ chosen plaintext where it reduced security of this cipher about 1 bit. Attack on PRESENT-80 has a data complexity of at most $2^{22}$ chosen plaintexts and computational complexity of $2^{79.37}$ encryptions that both complexities are lower than other cryptanalyses of PRESENT-80 so far

Reoperation in Horizontal Strabismus and its Related Risk Factors

This study was performed to determine the surgical outcomes and the related risk factors of second operation in patients with residual horizontal deviations. In this interventional case series study, a total of 119 patients with a history of reoperation were included (39 exotropia and 80 esotropia). Cases with consecutive strabismus, muscular palsy, systemic disease, lack of ocular fixation, and those, who had vertical deviation and Dissociated Vertical Deviation (DVD)&gt;5 Prism Diopters (pd) were excluded. Medial Rectus (MR) resection in residual Exotropia (XT) and Lateral Rectus (LR) resection in residual Esotropia (ET) were performed. Unilateral or bilateral operations were considered if the preoperative residual deviation was &lt; 20 pd or &gt; 20 pd, respectively. Success of the reoperation was considered if the postoperative angle of deviation was ≤ 10 pd. Unilateral and bilateral MR resection was performed in 26% and 74% of patients with XT, respectively, with greater dose response in unilateral cases (2.8 versus 2.6 mm/pd). Successful surgical outcomes were observed in 94.9% of patients with XT. Unilateral and bilateral LR resection was also performed in patients with residual ET, each in 50% of patients. Unilateral cases showed greater dose-response compared to bilateral ones (2.6 versus 2 mm/pd) and successful surgical outcomes were observed in 83.8% of patients with ET. No variable was found as a risk factor of reoperation in both groups. In conclusion, both LR and MR resection are easy and predictable surgical approaches with high success rate in patients with residual ET and XT. Generally, MR resection is more effective than LR resection. Unilateral operation is less recommended in the residual exotropic group, due to its lower success compared to the bilateral operation. Unfortunately, none of the mentioned variables were found to be the risk factor of reoperation in the sampled patients.Â