Additive manufacturing of thin-walled SS316L-IN718 functionally graded materials by direct laser metal deposition

Functionally graded materials (FGMs) are a good response to those advanced applications that service requirements are diverse and require high performance. Additive manufacturing (AM) technology, with its many advantages, including high flexibility for complex geometries and near-net-shape integration, has attracted special attention in the development of FGMs. In this research, the solidification behavior and microstructure evolution in the laser additive manufacturing of thin-walled stainless steel 316L-Inconel 718 graded materials have been studied with the help of solidification concepts in the welding metallurgy, according to the common principles of welding and additive manufacturing processes. For this purpose, optical and electron microscopy techniques, X-ray energy dispersive spectroscopy, and microhardness measurement were used along the build direction of FGMs with different transition designs. Microstructure evaluation showed that due to re-melting of layers, despite the increased undercooling in the build direction, morphological evolution occasionally occurred periodically between solidification modes, and due to thermal accumulation, a coarser microstructure is formed in the final layers. In addition, in the chemical analysis, it was observed that the mixing of adjacent layers caused by dilution led to a deviation of the composition distribution from the desired design. Also, the microsegregation of some elements during the non-equilibrium solidification of the process caused secondary phases such as carbides and intermetallic compound of Laves, which can have an adverse effect on the mechanical properties of the structure. However, microhardness variations along the cross-section of the samples showed that the gradation of the dissimilar thin-walled structure can effectively bring the properties and behavior of adjacent layers closer together and therefore be very useful in improving the service life

Investigating the relationship between physical and mental health among operating room personnel

BACKGROUND: Communities have been involved in adverse health factors at any point in time and have sought to improve community health and quality of life (QOL). The purpose of this study is to investigate the condition of physical and mental health and the relation between the two variables with each other in the operating room of hospitals in Shiraz, Iran.METHODS: This was a cross-sectional study performed on 192 staff of operating rooms of Shiraz University of Medical Sciences. The data for the study were collected through the General Health Questionnaire (GHQ) and the General Lifestyle Questionnaire (GLQ).RESULTS: Analyzing the results, the mean total scores of lifestyle and mental health were 333.93 ± 42.91 and 39.24 ± 12.59, respectively. In addition, the correlation coefficient between the total lifestyle and mental health scores was -0.411.CONCLUSION: Since the operating room is the most sensitive part of any hospital and the so-called heart of the hospital, special attention should be paid to staff working in this department, as any disruption to the operating room staff is not only harmful to them. Rather, it has many detrimental effects on patients and the health system. Therefore, given the stressful environment of the operating room, managers should promote operating room programs focused on reducing stress and by conducting classes and training sessions, improve the mental and physical health of the operating room personnel

Comparison of the Effects of Er, Cr: YSGG Laser and Super-Saturated Citric Acid on the Debridement of Contaminated Implant Surfaces

Introduction: Several techniques such as using citric acid, plastic curettes, ultrasonic devices, and lasers have been suggested for debridement of contaminated implant surfaces. This comparative investigation aimed to assess and compare the effects of Er, Cr: YSGG laser and super-saturated citric acid on the debridement of contaminated dental implant surfaces.Methods: In this in-vitro study, 12 contaminated failed implants were collected and randomly divided into 2 groups (6 in group A, and 6 in group B). Also, one implant was considered as the control. The implants were horizontally sectioned into coronal and apical portions and subsequently irradiated by Er, Cr: YSGG laser in coronal and citric acid in apical in group A and the opposite in group B. In order to evaluate the effect of water spray on the laser section, half the laser portion of the implants was irradiated using water, while the other half was irradiated without water with an irradiation time of 1 minute.Results: Results revealed that calculus and plaque removal was greater in the laser part of both groups (with and without water) compared to citric acid parts and the correlation between calculus removal and surface roughness were statistically significant. Furthermore, the surface roughness in the citric acid parts was significantly higher than in laser parts. Water spray during irradiation had a very small influence on understudy factors.Conclusion: Based on the results of this study, the Er, Cr: YSGG laser was more effective in calculus removal and caused less surface roughness compared with citric acid application

The Relationship Between Strategic Thinking and Hospital Managers’ Productivity in Teaching Hospitals of Shiraz

Background: Using different methods of strategic thinking is essential for organizations such as hospitals; without them, many organizations will not survive. The aim of the present study is to evaluate the relationship between strategic thinking and management productivity in teaching hospitals of Shiraz. Objectives: Because of the importance of strategic management in organizational productivity, the present study is conducted with the goal of assessing the relationship between strategic thinking and hospital managers’ productivity. Patients and Methods: This descriptive-correlational study was conducted in 2015. The statistical population included all managers in different levels in the teaching hospitals of Shiraz (170 persons). Among these, 119 participants were selected through Cochran’s formula and a simple random sampling method. Data were collected by a questionnaire addressing strategic thinking based on Liedtka’s model and Hersey and Blanchard’s theory. Its validity was verified by a panel of experts and its reliability was measured in previous studies. Data analysis was performed in SPSS version 20 using descriptive and analytic statistics (analysis of variance (ANOVA), Pearson’s correlation test and t-test). Results: The average and Standard Deviation of strategic thinking managers was (2.2 ± 0.04), and productivity of management (2.32 ± 0.37) was estimated on the average level. There was a direct meaningful relationship between strategically thinking managers and productivity (r = 0.387, P < 0.001). The results also showed that there is a meaningful correlation between strategic thinking and sustainability, organizational support and understanding of the job. Conclusions: Due to the correlation between strategic thinking and productivity, we recommend educating and training managers in the use of strategic thinking, and that they understand its importance to productivity. Managers should understand that increasing efficiency in a competitive environment today is a necessity for survival

Printability and microstructure of directed energy deposited SS316l-IN718 multi-material: numerical modeling and experimental analysis

In the present paper, the interrelated aspects of additive manufacturing-microstructure-property in directed energy deposition of SS316L-IN718 multi-material were studied through numerical modeling and experimental evaluation. The printability concept and solidification principles were used for this purpose. The printability analysis showed that the SS316L section is more susceptible to composition change and lack of fusion, respectively due to the high equilibrium vapor pressure of manganese and the more efficient heat loss in the initial layers. However, the IN718 section is more prone to distortion due to the formation of a larger melt pool, with a maximum thermal strain of 3.95 × 10 in the last layer. As the process continues, due to heat accumulation and extension of the melt pool, the cooling rate decreases and the undercooling level increases, which respectively result in coarser microstructure and more instability of solidification front in the build direction, as also observed in the experimental results. The difference is that the dendritic microstructure of the IN718 section, due to the eutectic reaction L → γ + Laves, is formed on a smaller scale compared to the cellular microstructure of the SS316L section. Also, the decrease in cooling rate caused the secondary phase fraction in each section (delta ferrite in SS316L and Laves in IN718) to increase almost linearly. However, the hardness calculation and measurement showed similarly, even though with the transition from SS316L to IN718 the hardness is significantly increased due to higher yield strength of the matrix and the presence of Laves intermetallic phase (~ 260 HV0.3), the hardness in each section decreases slightly due to the coarsening of the microstructure from the initial layer to the final. [Abstract copyright: © 2022. The Author(s).

Indications for Corneal Transplantation at a Tertiary Referral Center in Tehran

Purpose: To report the indications and techniques of corneal transplantation at a tertiary referral center in Tehran over a 3-year period. Methods: Records of patients who had undergone any kind of corneal transplantation at Labbafinejad Medical Center, Tehran, Iran from March 2004 to March 2007 were reviewed to determine the indications and types of corneal transplantation. Results: During this period, 776 eyes of 756 patients (including 504 male subjects) with mean age of 41.3±21.3 years underwent corneal transplantation. The most common indication was keratoconus (n=317, 40.8%) followed by bullous keratopathy (n=90, 11.6%), non-herpetic corneal scars (n=62, 8.0%), infectious corneal ulcers (n=61, 7.9%), previously failed grafts (n=61, 7.9%), endothelial and stromal corneal dystrophies (n=28, 3.6%), and trachoma keratopathy (n=26, 3.3%). Other indications including Terrien′s marginal degeneration, post-LASIK keratectasia, trauma, chemical burns, and peripheral ulcerative keratitis constituted the rest of cases. Techniques of corneal transplantation included penetrating keratoplasty (n=607, 78.2%), deep anterior lamellar keratoplasty (n=108, 13.9%), conventional lamellar keratoplasty (n=44, 5.7%), automated lamellar therapeutic keratoplasty (n=8, 1.0%), and Descemet stripping endothelial keratoplasty (n=6, 0.8%) in descending order. The remaining cases were endothelial keratoplasty and sclerokeratoplasty. Conclusion: In this study, keratoconus was the most common indication for penetrating keratoplasty which was the most prevalent technique of corneal transplantation. However, deep anterior lamellar keratoplasty is emerging as a growing alternative for corneal pathologies not involving the endothelium

Masked comparison of two silicone hydrogel bandage contact lenses after photorefractive keratectomy

Purpose: To compare the efficiency and safety of two bandage contact lenses after photorefractive keratectomy (PRK). Methods: In this double-blind study, 45 patients (90 eyes) received PRK in both eyes and wore bandage contact lenses (BCLs), PureVision (Bausch & Lomb, Rochester, NY, USA) in one eye and PureVision2 (Bausch & Lomb, Rochester, NY, USA) in the other eye, randomly assigned. The medication regimen after surgery was the same for both eyes. The epithelial defect's size, conjunctival hyperemia and lens centration were graded objectively using slit-lamp biomicroscopy on days 1, 3 and 5 after surgery. Also ocular symptoms of discomfort including tearing, photophobia, foreign body sensation and visual fluctuations were assessed subjectively at each visit. Results: The mean epithelial defect size on the first day after operation was similar in eyes fitted with PureVision (30.08 ± 5.30 mm²) and PureVision2 (30.25 ± 5.72 mm2) lenses. (p = 0.79) Contact lens deposits and bulbar hyperaemia on days 1 and 3 after PRK were similar between the two eyes, but were significantly greater on day 5 for PureVision2 lenses. (p = 0.02; p = 0.04 respectively) There was no difference in contact lens decentration, and discomfort symptoms including pain, tearing, foreign body sensation, photophobia and visual fluctuations between the eyes fitted with PureVision and PureVision2. (p > 0.05) Conclusions: PureVision and PureVision2 contact lenses are equivalent as bandage lenses in important aspects such as corneal re-epithelialization and subjective comfort., although PureVision2 led to a higher incidence of contact lens deposits and conjunctival hyperemia early post-PRK

Additive manufacturing of functionally graded metallic materials: A review of experimental and numerical studies

Inspired by nature, advanced functionally graded materials (FGMs) are an appropriate response to high-performance multi-functional applications. The introduction of modern additive manufacturing technology to the processing of gradient metallic materials opened up a great opportunity for further development of this class of engineering materials owing to several advantages of this technology, e.g., high manufacturing flexibility. The phenomena prevailing in the additive manufacturing of gradient metallic materials, such as melting and solidification, have drawn special attention to this field from the viewpoint of materials science and engineering to the extent that many experimental and numerical research studies have been done in this regard in recent years. After briefly introducing FGMs and providing a brief overview of manufacturing methods with a focus on additive manufacturing processes, this paper discusses experimental studies in three sections: metal–metal, metal-ceramic, and metal-intermetallic gradient materials. Then, numerical studies are reviewed from the perspective of materials science and engineering. In the end, important results achieved so far are summarized and an outlook is provided for further research in the future

Topical interferon alpha-2b for treatment of noninvasive ocular surface squamous neoplasia with 360° limbal involvement

Purpose: To report the results of topical interferon alpha-2b (IFNα2b) for the treatment of ocular surface squamous neoplasia (OSSN) with 360° limbal involvement. Methods: In a prospective observational study, five patients with biopsy proven primary or recurrent OSSN with 360° limbal involvement received topical IFNα2b (3 million IU/ml, 4 times daily) and were followed from 8 to 12 months. Outcome measures included resolution of the lesion, relief of symptoms, systemic and ocular side effects, and recurrence rate. Results: Five patients including 4 primary OSSNs and one recurrent OSSN received topical interferon alpha-2b. The mean age was 60.2 (range: 52-73) years and mean follow up duration was 10.2 months. Clinical resolution of the tumor occurred in all cases 2 months after initiation of treatment and no patient developed ocular or systemic complications. No recurrence of OSSN developed during the follow up period. Conclusion: Topical recombinant IFNα2b appears to be an effective alternative treatment for OSSN with 360° limbal involvement. This approach precludes the high risk of limbal stem cell deficiency which results from surgical excision or topical chemotherapeutic agents