Troubleshooting and rectifying structural mechanics problems –- applied mechanics in industry

This paper outlines the general process of troubleshooting and rectifying unexpected structural mechanics problems in industrial plant and infrastructure. Typically the process includes the combination and correlation of site measurements (strain, vibration), and computational simulations (finite element analysis, computational fluid dynamics) to identify root cause sources and guide redesign and rectification means. Details of typical site installations are outlined, including mining machinery, gas pipelines, railway lines, manufacturing plant and ships. Four case studies are included, ranging from resin manufacturing tubular agitators suffering vortex induced resonance, ore grinding mills needing better access manhole design, mine dump trucks, and ship shafting issues

Redesign of Centrifugal Compressor Impeller by means of Scalloping

Case StudyImpellers of centrifugal compressors may experience resonance with vane passing frequencies, especially when operated away from the design conditions. Resonance can cause a serious structural damage to impeller. Complete redesign of an impeller to avoid resonance often requires major changes of the compressor stage design. This case study illustrates alternative approach to redesigning an impeller - scalloping of its coverplate and backplate. Scalloping changes impeller’s natural frequencies and allows achieving a separation margin from resonance, which is sufficient for reliable operation. At the same time, scalloping does not have a detrimental effect on impeller’s performances and allows to maintain existing configuration of compressor stage

Cucumber seedling dependence on cotyledonary leaves for early growth

O objetivo deste trabalho foi estudar o desempenho das folhas cotiledonares no crescimento inicial e estabelecimento de plântulas de pepino (Cucumis sativus L.). Grupos de duas plântulas uniformemente emergidas foram utilizados para quantificar o crescimento inicial e acúmulo de matéria seca, o efeito da intensidade e época de remoção dos cotilédones sobre o estabelecimento da plântula, e a contribuição de proteínas, aminoácidos e carboidratos dos cotilédones para o crescimento inicial. O estabelecimento das plântulas de pepino foi altamente dependente das folhas cotiledonares. As folhas cotiledonares foram fundamentais para o estabelecimento do sistema radicular. A presença de um cotilédone após a emissão da primeira folha verdadeira foi suficiente para manter o crescimento da parte aérea da plântula. Plântulas de pepino foram dependentes de ambas as folhas cotiledonares para sustentar o crescimento do sistema radicular, pelo menos até a equivalência entre área foliar e cotiledonar. A cobertura de uma ou ambas folhas cotiledonares antes da emissão da primeira folha verdadeira aumentou o conteúdo de carboidratos no cotilédone descoberto e nas folhas, comparado com a testemunha. O crescimento inicial de plântulas de pepino é altamente dependente das folhas cotiledonares, sendo a parte aérea menos dependente do que o sistema radicular. Danos nos cotilédones durante o crescimento inicial podem afetar o rendimento pela redução da densidade de plantas, um importante componente do rendimento, ou da taxa de crescimento e estabelecimento da plântula, que afeta a uniformidade da cultura.The objective of this work was to evaluate the dependence of cucumber (Cucumis sativus L.) seedlings on cotyledonary leaves for early growth and establishment. Sets of two uniform emerging seedlings were used to quantify the initial growth and dry matter accumulation, as well as the intensity and stage of cotyledon damage in seedling establishment and to determine cotyledon protein, amino acid and carbohydrate contributions to the growing seedling. Cucumber seedling establishment was found to be highly dependent on cotyledonary leaves. Root system establishment was highly dependent on the health of the aerial part. One cotyledon was enough to maintain aerial growth of seedlings after unfolding the first true leaf. Cucumber seedlings depended on both cotyledons to keep root system growth at least until leaf area was equivalent to cotyledon area. Covering one or both cotyledons of seedlings with one unfolded leaf increased carbohydrate content of uncovered cotyledon and leaves compared with control seedlings. Cucumber seedlings are highly dependent on cotyledonary leaves and aerial parts are less dependent than root system. Cotyledon damage at early stages of plant establishment would adversely impact crop yield by reducing plant density, an important yield component, or slowing down seedling growth and establishment

ras Oncogene Activation Does Not Induce Sensitivity to Natural Killer Cell—Mediated Lysis in Human Melanoma

An important phenomenon in tumor immunology that has come under recent attention is the impact of oncogene activation in tumor cells on the sensitivity to lysis by immune effector cells. Several studies suggested that transfer of an activated ras oncogene into cultured rodent fibroblasts induces susceptibility to natural killer cell (NK)-mediated lysis. Experiments using human tumor cells, however, have produced conflicting data on the effect of ras activation in this respect. In studying the activation of the oncogene c-myc, which is often overexpressed in human melanoma, we have found that in cell lines expressing high levels of Myc protein, the sensitivity to lysis by NK cells was dramatically increased due to reduced expression of Human Leukocyte Antigen B locus products. Since the N-ras oncogene was found to be activated in 15% of human melanomas, we examined the possibility that in melanoma, in analogy to the murine systems, the mutated ras oncogene may influence NK susceptibility of human melanoma cells. Two N-ras genes harboring frequently found mutations were cloned into an expression vector. Transfection of the IGR39D melanoma cell line with wildtype and mutant N-ras constructs yielded several ras-expressing clones that were tested for NK sensitivity. Neither high expression of the wildtype N-ras protein, nor expression of two mutant proteins (N61-arg, N61-lys) was shown to result in enhanced NK-mediated lysis. We conclude that activation of ras oncogenes does not lead to the induction of an NK-sensitive phenotype in human melanoma cells. J Invest Dermatol 103:117S–121S, 199

Tuberculosis care designed with barramarrany (family): Participatory action research that prioritised partnership, healthy housing and nutrition

Issue addressed Ongoing tuberculosis (TB) transmission in Aboriginal communities in Australia is unfair and unacceptable. Redressing the inequity in TB affecting Aboriginal peoples is a priority in Australia’s Strategic Plan for Tuberculosis Control. Improving TB care needs not to just identify barriers but do something about them. Privileging the voices of Aboriginal people affected by TB is essential to identify effective and enabling strategies. Methods A barramarrany (Aboriginal family) affected by recurring TB partnered with TB and Environmental Health teams using a participatory action research (PAR) methodology to improve housing health hardware and nutrition alongside biomedical TB prevention and care. A combination of the Ottawa Charter for Health Promotion; the International ‘End TB’ Strategy; and Aboriginal barramarrany leadership, worldviews and traditional values guided actions to reduce TB transmission. Results Together the partners improved housing hardware and access to nutritious food, so the barramarrany could create a setting for good health and wellbeing. These actions supported the barramarrany to regain the physical, social and emotional wellbeing to deal with day-to-day challenges and stresses. The barramarrany were able to better sustain supportive relationships; grow, prepare and eat healthy food; and participate in healthcare activities. The barramarrany could better engage with medical approaches for TB and four barramarrany members completed TB treatment. The PAR action-project enabled and supported early TB diagnosis, treatment and prevention. Conclusion Amplifying the voices of Aboriginal people and shared ownership of TB diagnosis, treatment and prevention by the barramarrany, was underpinned with principles of self-determination, capacity building and social justice. This PAR action-project provides further evidence that improving housing and nutrition can assist in Ending TB while improving wellbeing. So what? Our action-research project undertaken within a PAR framework demonstrates the implementation of End TB Strategies by utilising the Ottawa Charter’s five actions to promote health, by understanding and centralising the social determinants of health

Investigation of Salmonella Contamination of Pigs in Australia

Microbiological surveys of pigs before, during and after slaughter and processing have been conducted at abattoirs in Australia, to estimate the incidence and risk factors for Salmonella contamination on carcasses. In one such survey, approximately 10% of carcasses were positive for Salmonella contamination at the end of the slaughter line, although there was considerable variation between abattoirs and between herds in the incidence of contamination. A range of Salmonella serotypes was recovered from carcasses, with the most common being S. derby, S. give, S. anatum, and S. ohio. The incidence of Salmonella contamination on carcasses varied along the slaughter line: some contamination on the skin surface of carcasses survived scalding and dehairing, despite the temperatures achieved during these processes

Cultural and serological analysis of the salmonella status of Australian pig production

The microbiological quality of food of animal origin is receiving widespread scrutiny as outbreaks of food-borne disease are increasingly reported in developed countries. In Australia, the pig industry has embarked on a national program to define and enhance the quality, including microbiological quality, of pig meat. The National Pig Meat Hygiene Program (PMHP) is part of this initiative, and aims to develop baseline data for microorganisms on pig meat, including public health pathogens, and to develop and implement management strategies to enhance the microbial quality of Australia\u27s pig meat production. The study reported here measured salmonella contamination on pig meat and carcases sampled nationwide, and adapted and validated an enzyme linked immunosorbent assay (ELISA) for evaluating the salmonella infection status of pig herds