13,770 research outputs found

    Modelling Tensile Behaviour of Stir-cast Aluminium Matrix Composites (AMCs) Using Factorial Design of Experiments

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    Aluminium based metal matrix composites (MMCs) with ceramic reinforcement are finding extensive applications in aerospace, automobile, agricultural farm machinery and other areas which demand combination of properties such as high strength, stiffness, wear resistance, high temperature resistance, etc. In particular, components comprising Al7075 alloy matrix, reinforced with alumina (Al2O3) particulates, are reported to excel their monolithic counterparts. Liquid metal route and powder metallurgy are the most widely used fabrication techniques to produce these MMCs. The former has advantages such as easy adaptability, low cost and possibility of subjecting the cast components to secondary processes like forging, rolling and extrusion for producing the final components. This paper presents the details of developing a mathematical model to predict the tensile behavior like ultimate tensile strength (UTS) and percentage elongation of the as-cast Al7075/Al2O3 in terms of size and % fraction of Al2O3, holding temperature and holding time; using factorial design of experiments (DoE). Adequacy of the models was tested using Fisher's F-test. UTS of the composite was increased by 20%compared to that of matrix and % elongation was reduced by around 30%. Keywords: MMC, UTS, % elongation, Design of experiments, Modelling

    Quantifying and assessing impacts of building processes in a triple bottom line approach

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    The paper is based on a research project undertaken by the University of Technology, Sydney in examining the integration of economic, social and environmental considerations throughout the building process of a development. The project comprises the first stage, a literature review and model development, followed by the second stage, model implementation through case studies. The paper presents the first stage of the research project in a literature review and model development. The paper reviews the current application of environmental building assessment tools and their impacts on the construction industry. The importance of building process in environmental assessment is also indicated. The paper also seeks to analyze building performance using a triple bottom line approach on a life cycle perspective. The major activities in the building process are identified and presented on how they influence sustainable performance. Finally the paper presents a model that combines economic, social and environmental assessments into a single indicator to aid decision making

    Towards an Understanding of Factors Controlling Seed Bank Composition and Longevity in the Alpine Environment

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    The ability of seeds to regenerate from soil seed banks has long been recognized as a key survival strategy for plants establishing new niches in highly variable climates of alpine environments. However, the fundamental aspects of evolutionary/selective forces for seed bank development in alpine ecosystems are largely unknown. Here, we developed a model that describes dormancy, a high temperature requirement and a specific light/darkness regime at the time of seed shedding can preclude autumn germination, thus contributing to seed persistence until the next growing season. The benefits of these factors synchronising germination with the growing season are reviewed. Additionally, the importance of climatic variations of maternal environment affecting some of these factors is also discussed. It is suggested that the environmental conditions during the growing season partly control the seed persistence and seeds that fail to germinate are carried over to the next season. Species that have small (<3 mg) and round-shaped seeds tend to persist more easily in soil for over five years, than do the large or flat seeds. However, some large-seeded species also have the potential to establish short-term persistence bank. A literature survey reveals 88% of the alpine seeds have a mass <3 mg. Seed size has only a weak relationship with mean germination timing (MGT) indicating that reduced persistence in large-seeded species cannot be counteracted by quicker germination, but combined effects of other factors stimulating germination remain an open area to be studied. It is proposed that long distance dispersal (LDD) is limited in most-but not all-species, primarily due to the absence of specialized dispersal structures. However, among numerous dispersal modes, most species tend to be dispersed by wind. Thus, spermatophytes of alpine environments have a greater tendency to establish seed banks and spread the risk of germination to many years, rather than being dispersed to other micro-climates

    A retrospective study on long-term efficacy of intranasal lysine-aspirin in controlling NSAID-exacerbated respiratory disease

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    Purpose: Aspirin treatment after desensitization (ATAD) represents an effective therapeutic option suitable for NSAID-exacerbated respiratory disease (N-ERD) patients with recalcitrant disease. Intranasal administration of lysine-aspirin (LAS) has been suggested as a safer and faster route than oral ATAD but evidence for its use is less strong. We investigated nasal LAS therapy long-term efficacy based on objective outcomes, smell function, polyp recurrence and need for surgery or rescue therapy. Clinical biomarkers predicting response to intranasal LAS, long-term side effects and consequences of discontinuing treatment have been evaluated. Methods: A retrospective analysis of a database of 60 N-ERD patients seen between 2012 and 2020 was performed in March 2021. They were followed up at 3-months, 1-, 2- and 3-years with upper and lower airway functions assessed at each follow-up. Results: Higher nasal airflow and smell scores were found at each follow-up in patients taking LAS (p < 0.001 and p = 0.048 respectively). No influence of LAS on pulmonary function measurements was observed. Patient on intranasal LAS showed a lower rate of revision sinus surgery when compared to those who discontinued the treatment (p < 0.001). None of the variables studied was found to influence LAS treatment response. Conclusion: Our study demonstrates the clinical effectiveness of long-term intranasal LAS in the management of N-ERD in terms of improved nasal airflow and olfaction and a reduced need for revision sinus surgery. Intranasal LAS is safe, being associated with a lower rate of side effects when compared to oral ATAD. However, discontinuation of the treatment at any stage is associated with a loss of clinical benefit

    Role of circulating exosomal biomarkers and their diagnostic accuracy in pancreatic cancer

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    Background and Aim: New biomarkers have the potential to facilitate early diagnosis of pancreatic cancer (PC). Circulating exosomes are cell-derived protein complexes containing RNA that can be used as indicators of cancer development. The aim of this review is to evaluate the current literature involving PC patient groups for highly accurate exosomal biomarkers. Methods: The literature search followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eight-hundred and seventy-five studies were identified across various databases (Ovid MEDLINE, Embase, and Cochrane) published between 2009 and 2020. Nine studies fulfilled the inclusion criteria: human PC patients, diagnosis as outcome of interest, serum biomarker of exosomal content, reporting of diagnostic values, and disease progress. Area under the curve (AUC) of the exosomal biomarker was compared against that of CA19-9. Results: Nine papers were reviewed for relevant outcomes based on the inclusion criteria. These studies involved 565 participants (331 PC, 234 controls; male/female ratio 1.21; mean age 64.1). Tumor staging was reported in all studies, with 45.6% of PC patients diagnosed with early-stage PC (T1–2). The mRNA panel (ARG1, CD63, CK18, Erbb3, GAPDH, H3F3A, KRAS, ODC1) and GPC 1 reported the highest performing sensitivity and specificity at 100% each. The microRNA panel (miR-10b, miR-21, miR-30c, miR-181a, and miR-let7a), mRNA panel (ARG1, CD63, CK18, Erbb3, GAPDH, H3F3A, KRAS, ODC1), and GPC 1 showed a perfect AUC of 1.0. Five studies compared the AUC of the exosomal biomarker against CA19-9, each being superior to that of CA19-9. Conclusion: The potential of exosomal biomarkers remains promising in PC diagnosis. Standardization of future studies will allow for larger comparative analyses and overcoming contrasting findings

    Efficiency assessment of trypanocidal treatments in the research station of Avetonou in Togo

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    In Togo as elsewhere, among the animal trypanosomosis control strategies, the chemotherapy constitutes the most used method. In order to assess the efficiency of two trypanocidal drugs (isometamidium chloride and diminazene) on cattle, a longitudinal study was conducted from September to November 2011 in the research station of Avetonou located in the Prefecture of Agou in Togo. A parasitological survey was carried out on two groups of 90 cattle each (for a total of 180 cattle) using the buffy coat technique at regular intervals of two weeks over a total period of 56 days. The animals of the first group were treated with isometamidium chloride (0.5 mg/kg) and the second group (untreated animals) was used as a control group. The comparison of the incidence of trypanosomosis between the two groups was performed using three statistical tests: the Chisquared test, the test of risk Reduction, and the “Eisler ratio test”. These analyses revealed an inefficiency of the preventive treatment with isometamidium chloride at the dose of 0.5 mg/kg bodyweight contrarily to the curative treatment that was effective. For diminazene, used at a dose of 3.5 mg/kg bodyweight, strains of Trypanosoma vivax and Trypanosoma congolense were not eliminated in 14.29% of cases.Keyswords: Trypanocidal treatment, isometamidium, diminazene, Avétonou, Togo

    Risk of prostate cancer after isolated high-grade prostatic intraepithelial neoplasia (HGPIN) detected on extended core needle biopsy : a UK hospital experience.

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    Background High-grade prostatic intraepithelial neoplasia (HGPIN) is a precursor lesion to prostate cancer (CaP). UK-based studies examining the occurrence of isolated HGPIN and subsequent risk of CaP are lacking. Our aim was to assess the occurrence of HGPIN in a regional UK population and to determine whether in a retrievable cohort of such patients that had repeat extended core biopsies, there was an elevated risk of CaP. Methods A retrospective analysis of the pathology database was conducted at our institution (Lancashire Teaching Hospitals NHS Foundation Trust) for prostate biopsies recorded between January 2001 and December 2005 (all extended core biopsies). Those patients with isolated HGPIN on 1st set of biopsies were identified and, their clinical characteristics and pathological findings from subsequent biopsies (if any) were determined. The risk of CaP on subsequent biopsies based on presenting baseline PSA was stratified. Results Of 2,192 biopsied patients, there were 88 cases of isolated HGPIN of which 67 patients underwent one or more repeat biopsies. In this repeat-biopsy group, 28 CaP diagnoses were made. Age at first biopsy (P 20 ng/ml – 87.5%. Conclusion Based on our results, we recommend delaying the 1st repeat biopsy at low PSA range but to have a shorter interval to repeat biopsies at intermediate and higher PSA ranges
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