Effects of Inter-Layer Time Interval on Temperature Gradients in Direct Laser Deposited Ti-6Al-4V

Parts fabricated via additive manufacturing (AM) methods are prone to experiencing high temperature gradients during manufacture resulting in internal residual stress formation. In the current study, a numerical model for predicting the temperature distribution and residual stress in Directed Energy Deposited (DED) Ti–6Al–4V parts is utilized for determining a relationship between local part temperature gradients with generated residual stress. Effects of time-interval between successive layer deposits, as well as layer deposition itself, on the temperature gradient vector for the first and each layer is investigated. The numerical model is validated using thermographic measurements of Ti-6Al-4V specimens fabricated via Laser Engineered Net Shaping® (LENS), a blown-powder/laser-based DED method. Results demonstrate the heterogeneity in the part’s spatiotemporal temperature field, and support the fact that as the part number, or single part size or geometry, vary, the resultant residual stress due to temperature gradients will be impacted. As the time inter-layer time interval increases from 0 to 10 second, the temperature gradient magnitude in vicinity of the melt pool will increase slightly.Mechanical Engineerin

Plasma homocysteine concentrations in young patients with acute myocardial infarction

INTRODUCTION: Most studies indicate that increased plasma homocysteine level is a risk factor for coronary artery disease. However, data concerning the role of homocysteine in young patients with acute myocardial infarction (AMI) is scanty. The aim of this study was to study the possible association between homocysteine plasma levels and early-onset AMI. METHODS: This case-control study included 83 AMI patients and 83 healthy controls. Biochemical parameters were determined and homocysteine was measured by enzyme immunoassay. Multivariate logistic regression analysis was used to test the association of homocysteine with the occurrence of AMI. RESULTS: Homocysteine concentration in patients with AMI was higher than in controls (19.54±13.3 and 15.54±8.9 µmol/l, respectively, P=0.002). Hyperhomocysteinemia was associated with early myocardial infarction (odds ratio=5.05). Hypercholesterolemia (OR=4/21), opium addiction (OR=4/78) and age (OR=1/24) also had associations with AMI. CONCLUSIONS: Our results showed that homocysteine levels are elevated in young patients with AMI, and hyperhomocysteinemia is associated with early myocardial infarction; hence it should be evaluated in all young patients with AMI. © 2007, Isfahan University of Medical Sciences(IUMS). All rights reserved

Impact of a Single Spoiler on Scouring Depth Status Beneath a River Crossing Inclined Pipeline

Deep river crossing pipelines utilized to carry fluids are often placed upon the sand bed. Placement of pipe on the non-smooth bed would result in the production of some local gaps beneath the pipe. Asymmetric scouring is one of the main reasons for pipe underwater failures which are significant in pipeline management. So, in designing pipelines, knowing the interaction between pipelines and bed, and predicting the scour depth with respect to the pipe distance from the bed is significant to ensure that the pipe will finally deposit on the bed. Numerical models have been developed for predicting the balance depth of scouring beneath the pipelines. In this paper, the impact of pipe orientation on maximum scour depth beneath the pipelines is investigated. To do this, a pipe is modeled with various angles with the flow. To manage the local scouring, some spoilers are placed and modeled upon some pipes too. Also, in order to know the effects of placement of a pipe at various distances from the bed, the impact of placement of each pipe at a distance of 0.2D, 0.4D and 0.6D is investigated as well. To model the pipe with and without a spoiler, the finite element model Flow-3D is utilized and the results show good accordance with previous experimental studies and proof the current model’s precision in predicting the scour depth. Results show that in the placement of the pipe in angles not investigated before and also with the installing of a spoiler, the scour process has a reverse ratio with the distance which would result in full deposition of the pipe on the bed. The least scour depth belongs to the condition in which the pipe has a 130° angle with the side wall

Research of possibility of producing of Ice cream through substituting milk protein with condensed protein (FPC) of silver carp

Fish is a valuable nutritional source witch use of it in daily meal has a beneficial role on nutritional needs supply and also causes mental and physical health especially in people who have protein and food deficiencies. Unfortunately, per capita consumption of sea foods in Iran is 5.5Kg which is very lower than world standards (18 kg). So, study on fish ice cream formulation, by use of fish protein concentrate (FPC) instead of milk protein, had done to make variation in sea foods products and also increase per capita consumption of these kinds of foods. FPC has very high protein concentration and a lot of necessary amino acids like lysine and methionine. Also its protein is very digestible with highly biological value and it's PER in compare with casein PER is high. At first fish protein concentrate type A produced from silver carp in three steps by the extraction with isopropyl alcohol solvent and heat. Microbiological and physicochemical specifications of produced FPC by rules of FDA and FAO were accepted. Finally according to panel test results, substitution of 30 percent of milk with FPC in comparison with 50%, 70% FPC substitution prepared (P<0/05). Also microbiological and physicochemical specifications of product were tested and results in compare with national standards of Iran were accepted

A conceptual framework for determinants of customer satisfaction of fixed-line telecom services in Pakistan

With the progression of communication technologies, there has been a decline in people's utilization of fixed-line telephones. It is essential to ascertain the fundamental causes underlying this phenomenon. There are numerous assumptions that service providers tend to favor their interests. Gaining an understanding of the factors that contribute to client satisfaction may require a significant investment of effort. Consequently, this study aims to ascertain the determinants that impact consumers' happiness with their fixed-line telecommunications service. In order to achieve the objectives of the research, a theoretical framework is presented whereby consumer satisfaction is considered the dependent variable. At the same time, responsiveness, perceived value, perceived service quality, and staff attitude are regarded as independent variables. The primary objective of this study is to ascertain the key factors that significantly influence Customer Satisfaction with Fixed-Line Telecom Services in Pakistan

The Use of a Compression Device as an Alternative to Hand-Sewn and Stapled Colorectal Anastomoses: Is Three a Crowd?

BackgroundThe NiTi CAR™ 27 is a newer device that uses compression to create an anastomosis. An analysis of this device in the creation of colorectal anastomoses in humans has yet to be reported in the USA.MethodsA non-randomized, prospective pilot study of the NiTi CAR™ 27 device in patients undergoing a left-sided colectomy between March 2008 and August 2009 was performed.ResultsTwenty-three patients (9 men and 14 women) underwent a left-sided colectomy and compression anastomosis with the CAR™ 27 device. Minor morbidities, 3 of 23 (13%) patients, included one small postoperative abscess requiring antibiotics alone and two postoperative anastomotic strictures requiring balloon dilation. Major morbidities, 1 of 23 (4%) patients, included a partial anastomotic dehiscence/leak requiring surgical dismantling of the anastomosis and diversion.ConclusionThe CAR™ 27 device shows promise as a safe and effective alternative for the creation of colorectal anastomoses. However, studies in a larger patient population are warranted to demonstrate equivalence of this device

Opium use and risk of mortality from digestive diseases: A prospective cohort study

Objectives:Opium use, particularly in low doses, is a common practice among adults in northeastern Iran. We aimed to investigate the association between opium use and subsequent mortality from disorders of the digestive tract.Methods:We used data from the Golestan Cohort Study, a prospective cohort study in northeastern Iran, with detailed, validated data on opium use and several other exposures. A total of 50,045 adults were enrolled during a 4-year period (2004-2008) and followed annually until December 2012, with a follow-up success rate of 99. We used Cox proportional hazard regression models to evaluate the association between opium use and outcomes of interest.Results:In all, 8,487 (17) participants reported opium use, with a mean duration of 12.7 years. During the follow-up period 474 deaths from digestive diseases were reported (387 due to gastrointestinal cancers and 87 due to nonmalignant etiologies). Opium use was associated with an increased risk of death from any digestive disease (adjusted hazard ratio (HR)=1.55, 95 confidence interval (CI)=1.24-1.93). The association was dose dependent, with a HR of 2.21 (1.57-3.31) for the highest quintile of cumulative opium use vs. no use (P trend =0.037). The HRs (95 CI) for the associations between opium use and malignant and nonmalignant causes of digestive mortality were 1.38 (1.07-1.76) and 2.60 (1.57-4.31), respectively. Increased risks were seen both for smoking opium and for ingestion of opium.Conclusions:Long-term opium use, even in low doses, is associated with increased risk of death from both malignant and nonmalignant digestive diseases

Selective CO₂ capture in metal-organic frameworks with azine-functionalized pores generated by mechanosynthesis

Two new three-dimensional porous Zn(II)-based metal-organic frameworks, containing azine-functionalized pores, have been readily and quickly isolated via mechanosynthesis, by using a nonlinear dicarboxylate and linear N-donor ligands. The use of nonfunctionalized and methyl-functionalized N-donor ligands has led to the formation of frameworks with different topologies and metal-ligand connectivities and therefore different pore sizes and accessible volumes. Despite this, both metal-organic frameworks (MOFs) possess comparable BET surface areas and CO₂ uptakes at 273 and 298 K at 1 bar. The network with narrow and interconnected pores in three dimensions shows greater affinity for CO compared to the network with one-dimensional and relatively large pores-attributable to the more effective interactions with the azine groups