Study the Effect of Nickel Coating on Fatigue Life of Low Carbon Steel Exposed to Corrosive Environments

Nickel electroplating on low carbon steel are widely used in many industrial application due to its benefit in improving corrosion fatigue life, increasing coating thickness provide good protection against corrosion but in other hand reduce fatigue life in addition to its high cost so applying a relatively thin layer of the electroplated nickel may give an acceptable corrosion protection in low cost. In this paper the effect of relatively  thin layer ( 6 µ m )  electroplated nickel deposited by Watts type bath on the corrosion fatigue life of low carbon steel specimens exposed to lab air and 3% NaCl solution as  a corrosive environments was studied. Five groups of standard low carbon steel specimens were prepared for fatigue tests, Mechanical grinding was done for the all45 test specimens and after that Nickel electroplating coating was carried out to 18 specimens and mechanical polishing performed on the remaining 27specimens. Fatigue tests were carried out in air for nine specimens immediately after polishing and the remaining specimens were tested after exposing to lab air and 3% NaCl solution as corrosive environments for a period of 30 day using a reverse bending fatigue machine. Results indicate that fatigue life of relatively thin layer Nickel electroplated specimens was shorter by 4% than that of the uncoated mechanical polished specimens immediately tested in air and not exposed to corrosive environments, but it’s corrosion fatigue life was higher by 11.46%than that of polished specimens when both exposed to lab air for 30 day and by 21.68% higher when both exposed to 3% NaCl solution for 30 day , this study indicate that relatively thin layer ( 6 µ m )   Nickel electroplating decrease fatigue live of low carbon steel specimens exposed to un corrosive environment, but it improved corrosion fatigue life of low carbon steel specimens exposed to cyclic load and corrosive environment. Keywords: Nickel Plating; surface treatment; fatigue life; corrosion fatigue

Numerical Study of Piled Raft Foundation in Non-Homogeneous Soil Using Finite Element Method

This paper analyzes a piled-raft foundation on non-homogeneous soils with variable layer depth percentages. The present work aims to perform a three-dimensional finite element analysis of a piled-raft foundation subjected to vertical load using the PLAXIS 3D software. Parametric analysis was carried out to determine the effect of soil type and initial layer thickness. The parametric study showed that increasing the relative density from 30 % to 80 % of the upper sand layer and the thickness of the first layer has led to an increase in the ultimate load and a decrease in the settlement of piled raft foundations for the cases of sand over weak soil.  In clay over weak soil, the ultimate load of the piled raft foundation was increased, and the settlement decreased by increasing the clay cohesion of the upper layer from 20 kPa to 70 kPa. It was observed that the load shared by the raft was very effective when using dense sand in the upper layer. In the case of dense sand over stiff clay, the percent of load carried by the raft is (30-40) %. Although, for the case of stiff clay over soft clay, the load percentage was almost constant (16-20) %. While for other issues, the sharing load of raft foundation was close and had the same behavior, the load carried by raft is between (8-12) %.

Assembly of Smart Microgels and Hybrid Microgels on Graphene Sheets for Catalytic Reduction of Nitroarenes

Poly (N-isopropylacrylamide-acrylic acid) [p(NIPAM-AAc)] microgel was successfully fabricated using the precipitation polymerization method. Silver (Ag) nanoparticles and graphene oxide (G) were used to fabricate the following hybrid microgels: Ag-p(NIPAM-AAc) (Ag-HMG), Ag-G-p(NIPAM-AAc) (Ag-G-HMG), and G-p(NIPAM-AAc) (G-HMG). Ag-HMG, Ag-G-HMG, and G-HMG were characterized using a Zetasizer and UV-Vis spectroscopy. The reduction of a series of different compounds with comparable and distinct chemical structures was catalyzed by synthesized Ag-HMG, Ag-G-HMG, and G-HMG hybrid microgels. The average size of Ag nanoparticles was found to be ~50 nm. Ag nanoparticles were synthesized within microgels attached to G sheets. Ag-p(NIPAM-AAc), Ag-G-p(NIPAM-AAc), and G-p(NIPAM-AAc) hybrid microgels were used for the catalytic reduction of nitroarenes and dyes. By comparing their apparent rate constant (kapp), reduction duration, and percentage reduction, the activity of HMG (hybrid microgel) as a catalyst towards different substrates was investigated. Graphene sheets play role in electron relay among Ag nanoparticles and microgels.publishedVersio

Measuring depression and anxiety prevalence among Iraqi healthcare college students using hospital anxi ety and depression scale

Objective : The study aimed to 1) measure the prevalence of depression and anxiety among Iraqi pharmacy and medical students at a number of universities in Baghdad using Hospital Anxiety and Depression Scale (HADS) and 2) investigate the associ ation between various sociodemographic factors and students’ HADS scores. Methods : This study was based on a cross - sectional descriptive design in four universities in Baghdad, Iraq. Depression and anxiety were screened using an Arabic version of the HADS. An online survey was administered via Qualtrics to convenience samples of students at four colleges of pharmacy and a college of medicine between March and June 2018. Multiple linear regression was u sed to identify factors associated with depression and a nxiety symptoms among the participants. Results : The researchers received 750 usable surveys. The participating students spent more time browsing social media (6.64 hours/day) than studying (1.92 hours/day) and exercising (2.83 hours/week). Approximately forty - six percent (45.9%) of the participants had scores that indicated depression symptoms and one - quarter (24.8%) had scores that indicated depression borderline symptoms. More than one - half (52.1%) of the participants had scores that indicated anxiety s ymptoms, while 20.1% had scores that indicated anxiety borderline symptoms. According to the multiple linear regression analysis, more depression and anxiet y symptoms were significantly (p - value < 0.05) associated with higher study hours weekly and lower sl eep hours at night, academic achievement, and colleagues and family social support during exams. Conclusions : Pharmacy and medical students may be vulnerable to depression and anxiety because of long study hours.. To reduce their levels of anxiety and depr ession, they may need more social support, more exercise, more sleep, less social media use and a lower academic workloa

Evaluation of Existing Bond-Slip Relations for CFRP-Steel Joints and New Model for Linear and Nonlinear Adhesives

Existing bond-slip (τ-s) relations for fibre-reinforced polymer (FRP)-steel joints employ different shapes and mathematical expressions, inferring that their predictions of failure load and mode, and other interface properties, might be inconsistent or inaccurate. In this study, predictions of four widely used τ-s relations are evaluated using a large experimental database of 78 double-lap FRP-steel specimens. To facilitate the evaluation process, a robust finite element (FE) model is developed for each test, implementing data from either of the existing τ-s relations to define the FRP-steel interface. Comparisons between test and FE results indicated that the existing τ-s models were unable of predicting the ultimate load (Pu) and effective bond length (Leff) of FRP-steel joints, or the relation between Pu and bond length and that between Leff and FRP modulus (Ef). A new τ-s model is developed based on an inverse FE simulation, comparison with experimental results, and regression analysis. It considers the effects of Ef, the type of FRP reinforcement (sheet or plate), and applies to both linear and nonlinear adhesives. The model predictions were validated by comparing with results from small bond tests and large FRP-strengthened steel beams tested under bending, yielding excellent results for Pu, failure mode, and all other interfacial properties.Validerad;2022;Nivå 2;2022-07-22 (sofila)</p

Attenuation of Bone Morphogenetic Proteins (BMPs) Signaling Induces Granulosa Cell Sensitivity to Gonadotropins in Female Mouse

Several lines of evidence support the notion that Bone Morphogenetic Proteins (BMPs) and gonadotropic hormones are major regulators of ovarian follicle development by inducing gonadotropin-mediated steroid hormone production and regulating ovarian follicle cell proliferation. Research from our laboratory and elsewhere have demonstrated that BMPs play important roles during the early stages of folliculogenesis. Despite the extensive research to reveal the mechanism of interaction between BMPs and gonadotropic hormones in the process of folliculogenesis, the exact mechanism of such an interaction is not adequately understood. Previously, we developed a unique mouse model characterized by a short-term attenuation of the BMP signaling system using passive immunization against bone morphogenetic protein 4 (BMP-4) and bone morphogenetic protein receptor 1B (BMPR1B). This model unequivocally demonstrated that the attenuation of BMP action was an effective method of enhancing fertility reserve and promoting follicle and ovulation rates in female mice. In addition, this study pointed to the possibility of bi-directional mutual regulation between BMPs, Follicle-Stimulating Hormone (FSH), and Luteinizing Hormone (LH). To gain further insight into this mechanism we used this mouse model to examine the protein expression and mRNA level of BMPR1B, Follicle-Stimulating Hormone Receptor (FSHR) and Luteinizing Hormone/Choriogonadotropin Receptor (LHCGR) in multiple stages of follicle development in female mice. Immunofluorescent analysis of female mice treated with anti-BMPR1B antibodies showed a significant upregulation of BMPR1B, FSHR, and LHCGR in the ovarian granulosa cells during the main stages of follicle development, whereas treatment with anti-BMP4 antibodies showed no effect. In addition, attenuation of BMPR1B resulted in upregulation of the FSHR (exclusively expressed in the granulosa cell) and LHCGR mRNA levels in the ovary. The present study implies that BMPs engage indirectly in regulating the later stages of folliculogenesis, in addition to their direct role in the regulation of the early stages of follicle development, by enhancing granulosa cell sensitivity to gonadotropins through upregulating the receptor expression. We propose that our mouse model is siutable to elucidate the mechanism of interaction between BMPs and gonadotropins in folliculogenesis

Assembly of Smart Microgels and Hybrid Microgels on Graphene Sheets for Catalytic Reduction of Nitroarenes

Poly (N-isopropylacrylamide-acrylic acid) [p(NIPAM-AAc)] microgel was successfully fabricated using the precipitation polymerization method. Silver (Ag) nanoparticles and graphene oxide (G) were used to fabricate the following hybrid microgels: Ag-p(NIPAM-AAc) (Ag-HMG), Ag-G-p(NIPAM-AAc) (Ag-G-HMG), and G-p(NIPAM-AAc) (G-HMG). Ag-HMG, Ag-G-HMG, and G-HMG were characterized using a Zetasizer and UV-Vis spectroscopy. The reduction of a series of different compounds with comparable and distinct chemical structures was catalyzed by synthesized Ag-HMG, Ag-G-HMG, and G-HMG hybrid microgels. The average size of Ag nanoparticles was found to be ~50 nm. Ag nanoparticles were synthesized within microgels attached to G sheets. Ag-p(NIPAM-AAc), Ag-G-p(NIPAM-AAc), and G-p(NIPAM-AAc) hybrid microgels were used for the catalytic reduction of nitroarenes and dyes. By comparing their apparent rate constant (kapp), reduction duration, and percentage reduction, the activity of HMG (hybrid microgel) as a catalyst towards different substrates was investigated. Graphene sheets play role in electron relay among Ag nanoparticles and microgels