Validation of a model of psychosocial determinants of occupational health of geriatric nurses

The purpose of this study was to verify a model of relationships between psychosocial factors and health for 8066 francophone nurses working in geriatric care in Québec. A random sample of 1990 subjects was drawn and a participation rate of 77.9% and 55% was obtained for the two-time study taken twelve months apart. Based on the theory of Maddi and Kobasa (1984), the model was reproduced for the two-time periods with the aid of structural equations. The analyses showed that three variables exert a direct influence on psychological distress: professional burnout, occupational stressors and hardiness. Also, variables have a direct effect on burnout: listed in order of importance, these are hardiness, occupational stressors, work support, active strategies of coping and employment status. In dealing with the work stressors, the nurses who are hardy make use of active strategies of coping and look for support form their colleagues. The results of the study help to better understand the psychological and social resources that best favor adaptation of working women in highly demanding work environments. The fallout of the study converges towards the quality of life of helping professionals and towards the cost and quality of health and social services.     

Alpha-Tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance

BACKGROUND: Experimental and epidemiologic investigations suggest that alpha-tocopherol (the most prevalent chemical form of vitamin E found in vegetable oils, seeds, grains, nuts, and other foods) and beta-carotene (a plant pigment and major precursor of vitamin A found in many yellow, orange, and dark-green, leafy vegetables and some fruit) might reduce the risk of cancer, particularly lung cancer. The initial findings of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) indicated, however, that lung cancer incidence was increased among participants who received beta-carotene as a supplement. Similar results were recently reported by the Beta-Carotene and Retinol Efficacy Trial (CARET), which tested a combination of beta-carotene and vitamin A. PURPOSE: We examined the effects of alpha-tocopherol and beta-carotene supplementation on the incidence of lung cancer across subgroups of participants in the ATBC Study defined by base-line characteristics (e.g., age, number of cigarettes smoked, dietary or serum vitamin status, and alcohol consumption), by study compliance, and in relation to clinical factors, such as disease stage and histologic type. Our primary purpose was to determine whether the pattern of intervention effects across subgroups could facilitate further interpretation of the main ATBC Study results and shed light on potential mechanisms of action and relevance to other populations. METHODS: A total of 29,133 men aged 50-69 years who smoked five or more cigarettes daily were randomly assigned to receive alpha-tocopherol (50 mg), beta-carotene (20 mg), alpha-tocopherol and beta-carotene, or a placebo daily for 5-8 years (median, 6.1 years). Data regarding smoking and other risk factors for lung cancer and dietary factors were obtained at study entry, along with measurements of serum levels of alpha-tocopherol and beta-carotene. Incident cases of lung cancer (n = 894) were identified through the Finnish Cancer Registry and death certificates. Each lung cancer diagnosis was independently confirmed, and histology or cytology was available for 94% of the cases. Intervention effects were evaluated by use of survival analysis and proportional hazards models. All P values were derived from two-sided statistical tests. RESULTS: No overall effect was observed for lung cancer from alpha-tocopherol supplementation (relative risk [RR] = 0.99; 95% confidence interval [CI] = 0.87-1.13; P = .86, logrank test). beta-Carotene supplementation was associated with increased lung cancer risk (RR = 1.16; 95% CI = 1.02-1.33; P = .02, logrank test). The beta-carotene effect appeared stronger, but not substantially different, in participants who smoked at least 20 cigarettes daily (RR = 1.25; 95% CI = 1.07-1.46) compared with those who smoked five to 19 cigarettes daily (RR = 0.97; 95% CI = 0.76-1.23) and in those with a higher alcohol intake (> or = 11 g of ethanol/day [just under one drink per day]; RR = 1.35; 95% CI = 1.01-1.81) compared with those with a lower intake (RR = 1.03; 95% CI = 0.85-1.24). CONCLUSIONS: Supplementation with alpha-tocopherol or beta-carotene does not prevent lung cancer in older men who smoke. beta-Carotene supplementation at pharmacologic levels may modestly increase lung cancer incidence in cigarette smokers, and this effect may be associated with heavier smoking and higher alcohol intake. IMPLICATIONS: While the most direct way to reduce lung cancer risk is not to smoke tobacco, smokers should avoid high-dose beta-carotene supplementation.     

Investigating the decay rates of Escherichia coli relative to Vibrio parahemolyticus and Salmonella Typhi in tropical coastal waters

Using the size fractionation method, we measured the decay rates of Escherichia coli, Salmonella Typhi and Vibrio parahaemolyticus in the coastal waters of Peninsular Malaysia. The size fractions were total or unfiltered, <250 μm, <20 μm, <2 μm, <0.7 μm, <0.2 μm and <0.02 μm. We also carried out abiotic (inorganic nutrients) and biotic (bacterial abundance, production and protistan bacterivory) measurements at Port Dickson, Klang and Kuantan. Klang had highest nutrient concentrations whereas both bacterial production and protistan bacterivory rates were highest at Kuantan. We observed signs of protist-bacteria coupling via the following correlations: Protistan bacterivory−Bacterial Production: r = 0.773, df = 11, p < 0.01; Protist−Bacteria: r = 0.586, df = 12, p < 0.05. However none of the bacterial decay rates were correlated with the biotic variables measured. E. coli and Salmonella decay rates were generally higher in the larger fraction (>0.7 μm) than in the smaller fraction (<0.7 μm) suggesting the more important role played by protists. E. coli and Salmonella also decreased in the <0.02 μm fraction and suggested that these non-halophilic bacteria did not survive well in seawater. In contrast, Vibrio grew well in seawater. There was usually an increase in Vibrio after one day incubation. Our results confirmed that decay or loss rates of E. coli did not match that of Vibrio, and also did not correlate with Salmonella decay rates. However E. coli showed persistence where its decay rates were generally lower than Salmonella.     

Extraction and purification of Polyhydroxyalkanoates (PHAs): application of Thermoseparating aqueous two-phase extraction

Being biodegradable, non-toxic and renewable as well as having similar or better properties than commercial plastics, polyhydroxyalkanoates (PHAs) can be a potential game changer in the polymer industry. Although viewed as a sustainable alternative to petrochemicals due to its biodegradability, PHAs are plagued with low commercial value due to their high production and recovery costs. Having the benefits of providing a mild environment for bioseparation, being environment-friendly and scalable, together with it its distinctive thermoseparating properties and ease of recyclability, thermoseparating-based aqueous two-phase extraction (ATPE) has provided the eco-friendly and economical solution to the PHA dilemma. ATPE-influencing factors such as types of thermoseparating polymer, concentration of phase-forming components, pH, and effect of centrifugation were investigated. Under the condition of 14 wt/wt% of EOPO 3900 concentration, 14 wt/wt% of ammonium sulfate concentration and pH 6 without the needs for extra centrifugation steps, a recovery yield and a purification factor of up to 72.2% and 1.61 fold can be achieved with the copolymers which can be recycled and reused twice. Thermoseparating ATPE has thus been proven to be a powerful primary purification tool for PHAs.     

Response Surface Optimisation of an Oxalate–Phosphate–Amine Metal–Organic Framework (OPA-MOF) of Iron and Urea

Metal–organic framework (MOF) materials are well known for various application fields, such as engineering, and medical sciences. Here, the synthesis, and synthesis-optimisation of a novel oxalate-phosphate-amine MOF (OPA-MOF) for innovative agricultural applications is described, with urea as a structure-directing agent in a hydrothermal synthesis. Product properties conducive to proposed applications included yield, purity, elemental content (N, P, C), and oxalate-solubility, as important driving forces for functionality, which is based on the biomineralisation processes for the material’s decomposition in soil. A four-factors/two levels plus one (4²+1) factorial design included replicated zero-point and factors of time, temperature, urea input rate and dilution factor. 19 experimental runs results provided data for a Response Surface Method optimisation to determine factors resulting in a desired product at highest efficiency. The saddle-ridge shaped response surface highlighted system robustness for two factors (time/urea-input), and sensitivity for temperature and dilution factor. Optimal factor combinations initially appeared counterintuitive compared to expected results from factorial design outcomes, however confirmatory experiments validate model predictions. Consequently, the optimisation process was strongly justified for accurate determination of the optimal OPA-MOF synthesis conditions.     

Control chart system with independent quality characteristics

This article proposes an algorithm to design a control chart system consisting of several individual control charts, each of which monitors one of s critical quality characteristics (dimensions) x_i of a product. All of the characteristics x_i are assumed to be independent of each other. The algorithm designs all the charts within a system in an integrative and optimal manner. Consequently, the performance characteristics of the overall system as a whole can be considerably improved and the product quality will be further enhanced. Such improvement is achieved with minimum additional cost and effort. Furthermore, the floor operators can utilize and understand the optimal control chart system as easily as the conventional system. Some useful guidelines have also been brought forth to aid the users in adjusting the control limits of the control charts in a system.     

Direct tunneling gate leakage current in transistors with ultrathinsilicon nitride gate dielectric

We present a study on the characterization and modeling of direct tunneling gate leakage current in both N- and P-type MOSFETs with ultrathin silicon nitride (Si₃N₄) gate dielectric formed by the jet-vapor deposition (JVD) technique. The tunneling mechanisms in the N- and PMOSFETs were clarified. The electron and hole tunneling masses and barrier potentials for the different tunneling mechanisms mere extracted from measured data using a new semi-empirical model. This model was used to project the scaling limits of the JVD Si ₃N₄ gate dielectric based on the supply voltages for the various technology nodes and the maximum tolerable direct tunneling gate current for high-performance and low-power applications