Analysis of Micromixers on Reverse Osmosis Based Desalination Membranes

Corrugated membranes are used in desalination modules to improve membrane performance. In this study, in order to gain a deeper insight into the separation performance of these corrugated membranes, a computational fluid dynamics simulation was carried out for a proposed three-dimensional desalination modules containing triangular and square ribs attached to the membrane surface. Solution-diffusion membrane transport model, based on coupling water permeation rate with local salt concentration, was applied for membrane boundary condition involving selective removal of components in the feed channel. The local water flux, salt concentration, shear stress, and Sherwood number were monitored over the membrane surface to determine the effect of eddy promoter corrugations on high salt concentration mitigation and total water flux for Reynolds number of 100, 400 and 1000. Mathematical model and numerical methods employed are validated by comparing predictions against measurements reported earlier. The results show that corrugated membranes especially triangular chevrons enhance membrane performance profoundly at all flow rates. Water permeation rate is increased, concentration polarization is alleviated, and the potential fouling in the module is reduced by introducing corrugated membranes. Membrane performance enhancement is greater at higher flow rate

Computational Study of Desalination by Membranes

Water desalination by membranes constitutes the majority of the low-quality water purication systems that extends across many different techniques. This study considers transport phenomena in reverse osmosis (RO) and vacuum membrane distillation (VMD) modules using computational techniques. Reverse osmosis is a pressure-driven separation method using semi-permeable membranes featuring nanoporous structures. Vacuum membrane distillation is another emerging separation method relying on the temperature difference across the microporous hydrophobic membranes.The membrane separation process intrinsically gives rise to temperature polarization (TP) and concentration polarization (CP) which could be severe limitations in these systems. To eliminate these polarizations and increase the module performance various design adaptations are suggested, and the effectiveness of this modications are investigated using incompressible laminar/turbulent steady/unsteady computational fluid dynamics simulations. Fully coupled membrane transport models, which is Solution-Diffusion model for RO and Dusty Gas model for VMD, are employed where the local flow properties - concentration, temperature, pressure, and suction rate - are implicitly solved along the membrane surface to predict the permeate flux accurately.It is shown how a simple design adaptation is achieved by twisting the hollow fiber membrane module that creates desirable flow structures result in dramatic performance enhancement of hollow ber membrane (HFM) RO water desalination modules. Twisted HFM bundles induce swirling flow structures inside desalination modules that increase momentum mixing throughout. It is found that the twisted HFM module mitigates concentration polarization (CP) effects and increases transmembrane permeate flux by 5 - 9% for three flow rates considered. Frictional energy losses and increased pumping power associated with this subtle design alteration are small relative to projected gains in clean water production and there are in principle no additional required components associated with this geometry.Complex nature of the permeate transport through the hydrophobic membranes in VMD process is modeled, and the effect of membrane properties and spacers on the TP and CP mitigation are explored. Large-Eddy Simulations (LES) are employed to gain more insight into the unsteady nature of the flow phenomena. It is found that coupling not only the local temperature but also the local concentration along the membrane surface affects the permeate flux since elevated concentration reduces the water vapor pressure. Membrane pore size is the dominant membrane parameter which mandates the true transport mechanisms. TP and CP are more pronounced in higher feed temperatures, and spacers dramatically mitigate these polarizations by inducing turbulent and momentum mixing. Submerging the spacers into feed channel also increases the pressure drop which is a potential threat for membrane wetting so that it needs to be examined along with other performance criteria while designing an optimum VMD module

Characterization of Model-Based Uncertainties in Incompressible Turbulent Flows by Machine Learning

This work determines the inaccuracy of using Reynolds averaged Navier Stokes (RANS) turbulence models in transition to turbulent flow regimes by predicting the model-based discrepancies between RANS and large eddy simulation (LES) models and then incorporates the capabilities of machine learning algorithms to characterize the discrepancies which are defined as a function of mean flow properties of RANS simulations. First, three-dimensional CFD simulations using k-omega Shear Stress Transport (SST) and dynamic one-equation subgrid-scale models are conducted in a wall-bounded channel containing a cylinder for RANS and LES, respectively, to identify the turbulent kinetic energy discrepancy. Second, several flow features such as viscosity ratio, wall-distance based Reynolds number, and vortex stretching are calculated from the mean flow properties of RANS. Then these flow features are regressed onto the discrepancy using a Random Forests regression algorithm. Finally, the discrepancy of the test flow is predicted using the trained algorithm. The results reveal that a significant discrepancy exists between RANS and LES simulations and ML algorithm successfully predicts the increased model uncertainties caused by the employment of k-omega SST turbulence model for transitional fluid flows.Comment: ASME IMECE 201

Dan katkılı polikarbonat ince filmlerin optik ve fotoiletkenlik özellikleri

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Bu çalışmada polimer, NLO molekül DAN ve ftalosiyanin katkılı polimer ince filmler, daldırma yöntemi kullanılarak hazırlandı.Polimerik maddelerin düşük dielektrik katsayısına, yüksek optiksel geçirgenliğe sahip olmaları ve kolayca ince film formuna getirilip, uygun elektro optik devre elemanı formuna sokulabilmeleri bu maddeleri kristallere oranla daha cazip kılmıştır.Geçen 15?20 yıl içerisinde dünyanın çeşitli merkezlerinde polimerik maddelerin fiziksel ve optiksel özelliklerinin tespit edilmesi üzerine binlerce çalışma yapılmıştır. Uygulamada kullanılabilecek en uygun polimerik numune ve en uygun çalışma şartları araştırılmıştır.Bu çalışmada katkısız ve DAN ile Pc molekülü katkılı polikarbonat numeneleri incelendi. Bu numenelerin kırılma indisi, spektroskopik bir yöntemle tespit edildi. Literatürdeki değere göre nispeten küçük kırılma indisi n = 1.3 ( 632.8 nm) elde edildi. Kalınlığı yüzey pürüzlülüğü (perthometre) yöntemiyle ölçüldü. Filmlerin 4-5 kalınlığa sahip olduğu tespit edildi. IDT kaplı cam üzerine hazırlanmış ince filmlerin dc ve ac elektriksel iletkenlikleri farklı sıcaklık ve frekanslarda ölçüldü.Numunelerin lineer olmayan optiksel özellikleri için elektriksel kutuplama işlemleri uygulandı. Elektrik kutuplama ile ince filmlerin yapısındaki merkezi simetri kırılarak DAN (NLO) molekülleri bir yönde yönlendirildi. Moleküller bu şekilde dondurularak merkezi simetrik olmayan bir yapı oluşturuldu. Moleküllerin alan yönünde yönelimi soğurma spektrumunda ki azalma ile ispat edildi.Kutuplu ve kutupsuz filmlerin dc ve ac fotoiletkenlik ölçümü yapıldı. Fakat bu numunelerin fotoiletkenlik özelliği göstermediği tespit edildi.Anahtar Kelimeler: Polimer, NLO molekül, ftalosiyanin, ince film, kırılma indisi, elektriksel iletkenlik, elektriksel kutuplanma, fotoiletkenlik, merkezi simetrik yapı.Having low dielectric coefficient and high optical transperency and also easy fubrication in thin film form cheap mass production made polimeric materials superior over inorganic crystals. In order to find out the best polimeric materials for device application many work done over world in last 20 years.In this work undoped PC and DAN and Pc doped PC films prapered by dip coating method. The refractive indices of thin films measured through spectroscopic method. Relatively low refractive index value of 1.3 ( was found. Thicknesses of the films were measured by a perthometer. 4-5 of thickneses are found. Dc and ac electrical conductivities of thin films were measured at different temperatures and frequncies.For NLO properties of thin films the films were electrically poled. The centrosymmetry in thin films were broken through electrical poling process. DAN NLO molecules were aligned in the line of electric field direction. The reduction in peak value of absorption spectrum proved the non-centrosymmetric order in polimer thin films.The dc and ac fotoconductivity measurements of these samples were also carried out. However, it is found that these samples have not shown any photoconductivity properties.Key Words: Polymer, NLO molecules, phthalocyanine, DAN, thin film, refractive index, electrical poling, photoconductivity, central symmetric structure

Uncommon Location of Lipoma: Extraluminally Vagina

Background: Lipomas are defined as a soft mass of well-differentiated adipose cells among mesenchymal tumors. Considering the localization of lipomas, these masses are commonly seen in subcutaneous tissue. The female reproductive tract is a rare site for development of lipomas and clinical findings appear depending on the size and localization. The connection of the mass with the vagina lumen causes different clinical findings. Intraluminal tumors protrude and arise from the vulva, while extraluminal tumors lead to perineal swelling. This case describes clinical, ultrasonographic, histological examination, and surgical management of extraluminal vaginal lipoma.Case: The present study reports a case of extraluminal vaginal lipoma in a 10-year-old Pitbull crossbred presented with anamnesis of a protruded tissue from the vulvar lips and dysuria following 6-month swelling in the perineum. Clinical examination revealed that the swelling was obvious and localized mostly on the lower left side of the perineum and the vaginal mucosa was protruded from the vulvar lips due to a mass. By vaginal palpation, the mass was not associated with the vaginal mucosa. The mass was located in the perivaginal region and transvaginal ultrasonography revealed a hypoechogenic mass. Based on clinical and ultrasonographic findings, surgery was recommended. The mass was adherent to the serosa of the vagina and it did not enclose the vaginal mucosa. Excision of mass was performed with careful blunt dissection avoiding any urethral disruption and periurethral tissues. After the mass was determined to be extraluminal, there was no need for excision of the vaginal tissue with the mass during operation. Using histopathological examination the mass was identified as a lipoma composed of adipocytes. In addition, ovariohysterectomy was not recommended following the diagnosis of vaginal lipoma.Discussion: Lipomas uncommonly can be localized in unpredicted rare areas such as vagina and vulva in older bitches. Although the majority of reported benign tumors in dogs recommend the surgery, medical treatment including the steroid injections is the other option to limit the lipomas. Considering the vaginal tumors, the surgical approach is also planned as laparotomy since leiomyomas are more common than lipomas. This approach partially results from the adherence of tumors to vaginal tissue. In addition, the location of the mass together without the adjacent tissue damage depending on whether it is intraluminal or extraluminal would make complete tissue removal. In previous reports, while symptoms such as perineal hernia of the lipoma were emphasized, the connection of the lipoma with the vaginal lumen was not evaluated as a significant factor determining the surgical approach. The mass was not connected to the vaginal mucosa and it was determined as extraluminal lipoma in the present study. Mass excision was performed by blunt dissection, avoiding urethral disruption and periurethral tissues. Unlike the most common approach in leiomyomas, this report did not require a total vaginectomy to remove the mass from the vagina. The ovariohysterectomy was not needed to be performed in the present study as in intraluminal vaginal tumors. It was believed that adhesions of lipoma with vaginal lumen is a determining factor in the combination of surgical techniques such as episiotomy and/or ovariohysterectomy. Lipomas should be considered among the tumors in the vaginal region of dogs brought with the complaint of swelling in perineum and protrusion of vaginal tissue

Detection and partial characterization of two distinct walnut isolates of cherry leaf roll virus (CLRV)

Two new cherry leaf roll virus (CLRV) isolates (Ah and Ad) were isolated and detected from traditionally-grown walnuts that showed severe apical necrosis and chlorotic spots in systemically infected Cheneopodium amaranticolor, in the eastern part of Turkey. The 404 and 405 bp long DNA fragments of the 3’-non-coding region of both isolates from PCR reactions were cloned and sequenced. A significant genetic variability (up to 14% divergence between sequences) was found within the 3’ terminal region of viral genome of CLRV Turkish isolates compared with the isolates in databases. The sequence of Ad isolate was found to share 84 to 98% and the Ah isolate was found to share 85 to 97% nucleotide identity with corresponding sequences of the selected world isolates. An RNA riboprobe generated for CLRV-Ad isolate reacted also with the CLRV-Ah isolate in dot blot molecular hybridization test. Positive reactions were still visible in hybridization test when the extracts of infected fresh and dried leaf tissues of C. amaranticolor diluted 1:20. Western blot analysis revealed that the molecular mass of the coat protein of about 52 kDa for both isolates.Keywords: Walnut, CLRV, 3’ non coding regio

A bibliometric analysis of current trends, hotspots, and future aspects of endodontic-periodontal lesions

Aim: This study aims to examine the present findings, contemporary developments, and productivity of endodontic-periodontal (endo-perio) lesions based on the top 50 most-cited articles between 1990 and 2022. Methodology: An electronic search was carried out in the " Clarivate Analytics Web of Science, All Databases". After ranking the articles in descending order based on their citation counts, the first 50 relevant articles were selected. Parameters such as citation density, publication year, journal, country, institution, author, study design, evidence level, and keywords were analyzed. Spearman's correlation was used to determine associations between the number of citations and citation density. Results: There was a significant positive correlation between citation number and the age of publication (p<0.05). Articles were mostly published between 2011 and 2022. The Journal of Endodontics had the largest number of publications. The United States and The University of Southern California made the highest contribution. The majority of the articles were case reports. Ilan Rotstein, Se-Lim Oh, and Maryam Pourhajibagher were the most frequent first authors. Studies were frequently designed as case reports with evidence level V. "Endo-perio lesions" followed by "guided tissue regeneration" were mostly-used keywords. Conclusion: Regenerative procedures along with endodontic treatments have been utilized in the last decade to manage endo-perio lesions due to the developments in materials and techniques. Case reports could guide dental practitioners by demonstrating updated information in this field

Disease and treatment experiences of COVID-19 patients: A qualitative study

BACKGROUND/AIMS The study aimed to explore the perceptions of hospitalized COVID-19 patients' experiences regarding the disease and treatment process. MATERIAL and METHODS The study was carried out as qualitative research at a hospital in Turkey between June 17, 2020 and July 7, 2020. The sample consisted of eight COVID-19 patients hospitalized in service after intensive care treatment. The data were collected through an in-depth individual interview form. Each interview was transcribed verbatim, and a thematic analysis was performed. The Standards for Reporting Qualitative Research checklist was followed. RESULTS Three main themes were identified for patients' perceptions of the disease experiences and treatment process. The patients experienced negative emotions after being diagnosed with COVID-19, and they spent the isolation and treatment process communicating with their beloved ones over the phone, watching television, and praying. Having an infectious disease caused them to have anxiety and sadness, and they reported satisfaction with the physicians and nurses during the treatment process. CONCLUSION Psychological and sociocultural factors, religious values, and health policies can be effective in patients' perception of disease and treatment. It is recommended for healthcare professionals to be aware of the psychosocial problems of the hospitalized COVID-19 patients during the disease and treatment process, monitor them for post-traumatic stress disorder, and provide the necessary support

A Field Study On Fertılıty Traıts Of Holsteın Heıfer And Cows Artıfıcıally Insemınated Wıth Sexed Belgıan Blue Sperm And Growth Characterıstıcs Of Crossbreed Belgıan Blue _ Holsteın (F1) Male Calves

The study was conducted to investigate some reproductive traits of Holstein cattle inseminated with imported sexed male Belgian Blue semen and the growth characteristics of calves in Aydin province of Turkey. Totally 82 Holstein cattle including 29 heifers and 53 cows were inseminated. After the inseminations, some reproductive (the number of insemination per conception, conception rate, the dystocia rate, the rate of stillbirth) values were determined in the enterprises. The birth weights of the male calves were determined and in the following periods, the chest girth and body length values were determined for 6 months of age. In the study, it was observed that the average age of the first insemination was 14.05 months for heifers and 38.11 months for cows (P < 0:05). While more than half of the cows (52.08%) became pregnant in the first insemination, a great majority of the pregnancies (69.03%) of heifers occurred in the second inseminations (P < 0:05). The number of inseminations per conception were 2.13 and 1.79 for heifers and cows, respectively. While the conception rate was determined as 47.76% and 55.62% for heifers and cows respectively, dystocia rate were 43.10% and 25.75%, respectively. The average birth weight of the male calves were found as 42.75 kg and the 90th and 180th day live weights were 106.22 kg and 154.16 kg, respectively. While, the height at withers, body length and chest girth values were detected as 80.60 cm, 78.28 cm, 81.04 cm at birth, the same measurements were 94.45 cm, 94.22 cm and 109.79 cm; 108.46 cm, 110.88 cm and 129.45 cm for the 90th and 180th day, respectively. The corresponding study has clearly shown that the application in the project can create a dramatical meaning in dairy farms. This application can be used in dairy farms in a certain period to whole herd or a part of it. © 2022 Academic Publishing House. All rights reserved

Retroperitoneal ganglionörom

Nöroblastom, ganglionöroblastom ve ganglionörom sempatik sinir sistemini oluşturan, değişik derecelerde olgunlaşmış, primordial nöral krest hücrelerinden köken alan heterojen bir grup tümördür. Abdominal distansiyon, sol üst kadran ağrısı ve daire şikayetleriyle başvuran 12 yaşındaki erkek hastaya yapılan tetkikler sonucu rastlantısal olarak primer retroperitoneal ganglionörom saptanmıştır.Neuroblastoma, ganglioneuroblastoma and ganglioneuroma are tumors of varying maturity derived from the primordial neural crest cells that form the sympathetic nervous system. A primary extraadrenal retroperitoneal ganglioneuroma was found incidentally in a 12-year-old boy during a series of examinations for abdominal distension, left upper quadrant pain and diarrhoea