Evaluation of Eddy Viscosity Models in Predicting Free- Stream Turbulence Penetration

Turbulence schemes have long been developed and examined for their accuracy and stability in a variety of environments. While many industrial flows are highly turbulent, models have rarely been tested to explore whether their accuracy withstands such augmented free-stream turbulence intensity or declines to an erroneous solution. In the present study, the turbulence intensity of an air flow stream, moving parallel to a flat plate is augmented by the means of locating a grid screen at a point at which Rex=2.5×105 and the effect on the flow and the near-wall boundary is studied. At this cross section, the turbulence intensity is augmented from 0.4% to 6.6% to flow downstream. Wind tunnel measurements provide reference bases to validate the numerical results for velocity fluctuations in the main stream and at the near-wall. Numerically, four of the most popular turbulence models are examined, namely the oneequation Spalart-Almaras, the two equation Standard k , the two equation Shear Stress Transport and the anisotropy multi equation Reynolds Stress Models (RSM). The resulting solutions for the domain are compared to experimental measurements and then the results are discussed. The conclusion is made that, despite the accuracy that these turbulence models are believed to have, even for some difficult flow field, they fail to handle high intensity turbulence flows. Turbulence models provide a better approach in experiments when the turbulence intensity is at about 2% and/or when the Reynolds number is high

Bioactivation of 3D Cell-Imprinted Polydimethylsiloxane Surfaces by Bone Protein Nanocoating for Bone Tissue Engineering

Physical and chemical parameters that mimic the physiological niche of the human body have an influence on stem cell fate by creating directional signals to cells. Micro/nano cell-patterned polydimethylsiloxane (PDMS) substrates, due to their ability to mimic the physiological niche, have been widely used in surface modification. Integration of other factors such as the biochemical coating on the surface can achieve more similar microenvironmental conditions and promote stem cell differentiation to the target cell line. Herein, we investigated the effect of physical topography, chemical functionalization by acid bone lysate (ABL) nanocoating, and the combined functionalization of the bone proteins' nanocoated surface and the topographically modified surface. We prepared four distinguishing surfaces: plain PDMS, physically modified PDMS by 3D cell topography patterning, chemically modified PDMS with bone protein nanocoating, and chemically modified nano 3D cell-imprinted PDMS by bone proteins (ABL). Characterization of extracted ABL was carried out by Bradford staining and sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis, followed by the MTT assay for evaluation of cell viability on ABL-coated PDMS. Moreover, field emission scanning electron microscopy and profilometry were used for the determination of optimal coating thickness, and the appropriate coating concentration was identified and used in the study. The binding and retention of ABL to PDMS were confirmed by Fourier transform infrared spectroscopy and bicinchoninic acid assay. Sessile drop static water contact angle measurements on substrates showed that the combined chemical functionalization and nano 3D cell-imprinting on the PDMS surface improved surface wettability by 66% compared to plain PDMS. The results of ALP measurement, alizarin red S staining, immunofluorescence staining, and real-time PCR showed that the nano 3D cell-imprinted PDMS surface functionalized by extracted bone proteins, ABL, is able to guide the fate of adipose derived stem cellss toward osteogenic differentiation. Eventually, chemical modification of the cell-imprinted PDMS substrate by bone protein extraction not only improved the cell adhesion and proliferation but also contributed to the topographical effect itself and caused a significant synergistic influence on the process of osteogenic differentiation

Biological Evaluation of a Novel Tissue Engineering Scaffold of Layered Double Hydroxides (LDHs)

Bone Tissue Engineering (BTE) Composed of Three Main Parts: Scaffold, Cells and Signaling Factors. Several Materials and Composites Are Suggested as a Scaffold for BTE. Biocompatibility is One of the Most Important Property of a BTE Scaffold. in This Work Synthesis of a Novel Nanocomposite Including Layered Double Hydroxides (LDH) and Gelatin is Carried Out and its Biological Properties Were Studied. the Co-Precipitation (PH=11) Method Was Used to Prepare the LDH Powder, using Calcium Nitrate, Magesium Nitrate and Aluminum Nitrate Salts as Starting Materials. the Resulted Precipitates Were Dried. X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) Analyses Were Used to Characterize the Synthesized Powders. the Results Demonstrated the Presence of Nanocrystals of Ca-LDH and Mg-LDH as Hexagonal and Layered Morphology. the Obtained Powders Were Composed to Gelatin Via Solvent Casting Method Then Freez Dried. the Scaffold Was Prepared Via Membrane Lamination Method from the Resulted Layers that Linked Together with Gelatin as Binder. in Order to Investigate the Scaffold Cytotoxicity MTT Assay Was Done with a Osteosarcoma Cell Line. No Toxic Response Was Observed in Specimens. as a Major Result, It Was Demonstrated that the Specimen Showed a Significant Cellular Response. Then Osteosarcoma Cells Were Cultured for 7-Day and 14-Day Extract of Powders. the Composites Osteoconductivity Was Investigate with Cells Alkaline Phosphatase Extraction. the Results Demonstrated that the Ca-LDH/gelatin Composite Scaffold Has a Good Potential for Bone Tissue Engineering Applications and Mg-LDH Specimen Has a Better Osteconductivity. © (2012) Trans Tech Publications

Targeting delivery of lipocalin 2-engineered mesenchymal stem cells to colon cancer in order to inhibit liver metastasis in nude mice

One of the major obstacles in cancer therapy is the lack of anticancer agent specificity to tumor tissues. The strategy of cell-based therapy is a promising therapeutic option for cancer treatment. The specific tumor-oriented migration of mesenchymal stem cells (MSCs) makes them a useful vehicle to deliver anticancer agents. In this study, we genetically manipulated bone marrow-derived mesenchymal stem cells with their lipocalin 2 (Lcn2) in order to inhibit liver metastasis of colon cancer in nude mice. Lcn2 was successfully overexpressed in transfected MSCs. The PCR results of SRY gene confirmed the presence of MSCs in cancer liver tissue. This study showed that Lcn2-engineered MSCs (MSC-Lcn2) not only inhibited liver metastasis of colon cancer but also downregulated the expression of vascular endothelial growth factor (VEGF) in the liver. Overall, MSCs by innate tropism toward cancer cells can deliver the therapeutic agent, Lcn2, and inhibit cancer metastasis. Hence, it could be a new modality for efficient targeted delivery of anticancer agent to liver metastasis. © 2015, International Society of Oncology and BioMarkers (ISOBM)

Neutrophil Gelatinase-Associated Lipocalin induces the expression of heme oxygenase-1 and superoxide dismutase 1, 2

Lipocalin-2 (Lcn2, NGAL) is a member of the lipocalin super family with diverse function such as the induction of apoptosis, the suppression of bacterial growth, and modulation of inflammatory response. Much interest has recently been focused on the physiological/pathological role of the lipocalin-2 that is considered to be a novel protective factor against oxidative stress. However, its precise biological roles in this protection are not fully understood. In this report we intended to test the effect of lipocalin-2 on the expression of heme oxygenase (1, 2) and superoxide dismutase (1, 2) which are two strong antioxidants. NGAL was cloned to pcDNA3.1 plasmid by using genetic engineering method. The recombinant vector was transfected to CHO and HEK293T to establish stable cell expressing NGAL and the expression of HO-1, 2 and SOD1, 2 were compared with appropriate controls byRT-PCR and western blot. On the other hand, expression of NGAL was suppressed by siRNA transfection in order to study the effect of lipocalin-2 on mentioned genes/proteins. The results showed that the expression of HO-1 and SOD 1, 2 enzymes were higher in cells expressing recombinant lipocalin-2 compared with the control cells. Although the expression of HO-1 was lower in NGAL silencing cells, the expression of SOD1 and SOD2 were higher. Our data suggest that NGAL is a potent inducer of HO-1 and somewhat SOD1 and SOD2 and it appears that part of antioxidant property of NGAL could be attributed to the induction of HO-1and SOD 1, 2. © Cell Stress Society International 2009

Mutations in Thalassemia Carrier Couples: The Importance of Prenatal Diagnostic Tests

Background: Thalassemia carrier couples play an important role in increasing thalassemia patients. The study of thalassemia genotypes in carrier couples is also effective in improving genetic counseling for them. The aim of this study was to investigate the prevalence of thalassemia mutations and genotypes in couples. Methods: This cross-sectional study was performed on 241 couples who were suspected of thalassemia from April 2018 to March 2020 in Lorestan province. Statistical analysis of data was performed using SPSS software 16.0 (SPSS Inc., Chicago, IL, USA). Online tools such as www.ithanet.eu/db/ithagenes and http://globin.bx.psu.edu/hbvar/menu.html were also used to match patients' mutations with known cases. Results: IVSII-1 (G>A), CD36-37 (-T), IVSI-110 (G>A), —Med, and alpha(3.7 )were the most common mutations in the beta and alpha genes, respectively. IVSII-1 (G>A) 130/13 (26.1), CD36-37 (-T) beta 0/beta (21.1), and IVSI-110 (G>A) beta 0/beta (10.3) genotypes were the most common in women. The frequency of these genotypes in men were 24.8, 28.6, and 12.8, respectively. Among alpha thalassemia carriers, the alpha(3.7)alpha/alpha alpha genotype had the highest frequency among women (3.7) and men (5.3). Alpha and beta-thalassemia were 15 and 13 times higher in related women and 18 and 9 times higher in related men than non-related ones, respectively. This difference was statistically significant (p < 0.001). In addition, 12.8 of fetuses were thalassemia major, 31.9 beta thalassemia minor, and 10.3 normal. Conclusions: Thalassemia screening in related couples plays an important role in reducing thalassemia major infants

Evaluation of growth inhibitory and apoptosis inducing activity of human calprotectin on the human gastric cell line (AGS)

Background: Calprotectin is cytotoxic agent that its anti-tumor effects are governed through suppression of topoisomerase II; a key enzyme in apoptosis. In previous studies, cytotoxicity and apoptotic effects of calprotectin are shown on different cancer cell lines, but not human gastric cancer cell lines. In the present study, cytotoxicity and apoptotic effects of calprotectin on human gastric adenocarcinoma cancer cell line (AGS) were evaluated. Methods: The AGS cells were exposed to the different concentrations of calprotectin for 24, 48 and 72 hours. Cell proliferation was assessed using dimethylthiazol diphenyl tetrazolium bromide assay and dye exclusion tests. For evaluation of cytotoxic mechanism in calprotectin on AGS cells, flow cytometric analysis was performed. Results: Our results revealed that calprotectin induces growth inhibition of AGS in a dose- and time-dependent manner. Results of this investigation showed that sensitivity of AGS cells to cytotoxic effect of human calprotectin was highly remarkable. In addition, growth inhibitory effect of this cytotoxic agent mostly was governed through induction of apoptosis in the AGS cells. Conclusion: These findings indicated that calprotectin induces growth inhibition and apoptosis in the AGS cells

Corrosion resistance evaluation of rebars with various primers and coatings in concrete modified with different additives

Corrosion of steel rebars in concrete can reduce the durability of concrete structures in coastal environments. The corrosion rate of these concrete structures can be reduced by using suitable concrete additives and coating on rebars. This paper investigates the corrosion resistance of steel rebars by the addition of pozzolanic materials including fly ash, silica fume, polypropylene fibers, and industrial 2-dimethylaminoethanol (FerroGard 901) inhibitors to the concrete mixture. Three different types of rebars including mild steel rebar st37, and two stainless steel reinforcements, AISI 304 and AISI 316, were used. Various types of primer and coating including alkyd based primer, hot-dip galvanized coatings, alkyd top coating, zinc-rich epoxy primer, polyamide epoxy primer, polyamide epoxy top coating, polyurethane coatings, double layer of epoxy primer and alkyd top coating, and double layer of alkyd primer and alkyd top coating were applied on steel rebars to investigate the effect of coating type on the corrosion resistance of steel rebars in concrete. Polarization tests, electrochemical impedance spectroscopy, compressive strength and color adhesion tests were conducted. The best reinforced concrete mix design for corrosion resistance was the one including the rebar with zinc-rich epoxy primer and 25% fly ash, 10% silica fume, and 3% FerroGard 901 inhibitors by cementitious material weight. Polyurethane was the best coating due to the highest strength and the lowest corrosion rate. Alkyd primer was the weakest coating, although it was the most economical coating system

Blood Coagulation Disorders Among the Iranian Population: a Systematic Review

Background: Blood coagulation disorders are one of the causes of mortality. Therefore, the study of coagulation disorders is also important. This systematic review was conducted to investigate blood coagulation disorders in the Iranian population. Methods: Searches in electronic databases such as Web of Science, PubMed, Scopus, SID, ProQuest, and Magiran from May 10, 1990 to May 10, 2019 were performed according to PRISMA guidelines. Cross-sectional, cohort, experimental, and case-control studies were included according to the inclusion criteria without gender and language restrictions. Results: After screening and selection, 14 studies were selected for data extraction. Accordingly, the most common blood coagulation disorder in the south of Iran was a defect in FXIII (599 of 1,165). C.559T>C (27 of 189) and c.562T>C (20 of 189) mutations had the highest frequency. The most common FXIII polymorphism among the Iranian Azerbaijanis was Val34Leu (203 of 410). The second most common coagulation disorder was FV Leiden (396 of 1,165). Then, c.1691G>A (151 of 396) was the most common mutation. Conclusions: This study shows that the most critical coagulation disorder among the Iranian population is FXIII deficiency and the most common mutation is c.562T>C. © 2023 Verlag Klinisches Labor GmbH. All rights reserved

Characterization of poly(3-hydroxybutyrate)/nano-hydroxyapatite composite scaffolds fabricated without the use of organic solvents for bone tissue engineering applications

Poly(3-hydroxybutyrate)/nano-hydroxyapatite (PHB/nHA) composite scaffolds were fabricated without the use of organic solvents at different mass fractions of HA nanoparticles. HA nanoparticles were homogeneously dispersed as primary particles in the polymer matrix of the scaffolds at 10 and 15 wt.% nHA content. Agglomeration of HA nanoparticles occurred when the nHA content of the scaffolds reached 20 wt.%. All the scaffolds had high porosities with interconnected porous structure and optimized pore size ranges. Mechanical properties of all the scaffolds were in the range of mechanical properties of cancellous bone. Scaffolds were biocompatible to MG-63 cells inthe indirect method of cytotoxicity evaluation. Also, the morphology of the attached MG-63 cellsin direct contact with the scaffolds indicated the appropriate cell-scaffold interaction. Thus, the PHB/nHA composite scaffolds investigated in this study tend to be favorable for bone tissue engineering applications