BACKGROUND: The prevalence of neck and low back musculoskeletal injuries in transit operators has been shown to be high; with work absences exceeding double the National average. There is a lack of biomechanical data generated from field researches to inform on musculoskeletal risk associated with transportation and driving occupations. Instead there has been a reliance on simulated driving and questionnaire-based research. OBJECTIVES: This study was designed to examine the musculoskeletal and biomechanical stresses experienced by urban bus drivers. The main objective was to obtain a baseline understanding of sitting posture, muscle activiation and subjective ratings of stress during regular driving tasks. PARTICIPANTS: Fifteen urban city bus drivers were recruited for this study. METHODS: Bus drivers drove the same 65-minute bus route once, at the same time of day, in the same preselected bus. Wireless surface electromyography monitored muscular activity of the drivers' neck, upper trapezius, and erector spinae and video analysis and seat pressure mapping was used to monitor changes in driving posture. A health and lifestyle questionnaire was administered to record specific neck and back pain experienced by drivers as well as to provide lifestyle habits. RESULTS: Drivers were found to exhibit non-neutral postures for less than 30% of the time while conducting routine tasks of turning and stopping for passenger loading and unloading. The neck posture was the greatest concern in terms of non-neutral posture and this was supported by the higher muscle activation to the neck musculature. There was significant posture adjustment made during the one-hour driving period with the adjustments increasing with driving time. CONCLUSION: Activities associated with bus driving appear to require the use of non-neutral postures an increase in muscle activation. Significant postural adjustments were needed over the one-hour observation period suggesting that the musculoskeletal demands may increase over a regular 12-hour shift.
Oxalate is a major source of scaling during the manufacturing process of bleached mechanical pulps and the majority is formed during the peroxide bleaching stage. In this paper, we investigated the effect of using Mg(OH) 2 as an alkali source during peroxide bleaching on the formation of oxalate and its partition between soluble and precipitated oxalates. We found that at the same brightness target, the total amount of oxalate formed is similar between the Mg(OH) 2 -based peroxide system and the conventional NaOH-based system, however, almost all of the newly formed oxalate from the former was found in the soluble state, while in the NaOH-based peroxide process, a large fraction is in the precipitate form. Therefore, the oxalate-related scaling is significantly less or even negligible during the Mg(OH) 2 -based peroxide process. The underlying mechanism accounting for the above observation will be discussed.
Pressure garments are the main method of treatment and prophylaxis for hypertrophic burn scars. The pressure they exert on the scarred skin prevents contractures forming, reduces the itchiness and pruritus associated with active hypertrophic scars, and is believed, by many, to hasten normalization of the scar tissue. The pressure exerted is believed to be critical to treatment success and can be predicted based on laboratory measurement of the fabric's tension profile. All previous research on the pressures delivered by pressure garments has been undertaken using dry fabrics in either laboratory or clinical conditions. However, many patients have complained of increased perspiration when wearing pressure garments, and many burn victims live and work in hot conditions where high levels of perspiration may be expected. This article investigated the impact of moisture content on fabric tension and thus the pressure exerting ability of pressure garments. Four different fabrics currently used in the construction of pressure garments were evaluated in seven different states of "wetness" from completely dry to completely saturated in water or artificial perspiration. Standard laboratory methods were used to measure the initial tension in fabrics and the tension after 11 cycles of extension. Pressures that would be exerted by these fabrics were calculated using the Laplace law. The results of this study showed that the tension, and therefore pressure delivering ability, of fabrics used in pressure garments was significantly reduced when they were wet but that the amount or type of "wetness" did not have a significant effect on pressure delivering ability.
We sought to establish the impact of pressure garment design variables, moisturizer use, and laundry method on the ability of pressure garments to maintain their pressure delivering potential, indicated here by garment tension, over time and use. Twenty-six sets of three replicate pressure garment sleeves were constructed from four powernet fabrics, using three reduction factors and six sleeve dimensions. These pressure garment sleeves were extended for 23 hours on static cylinder models followed by hand or machine laundry up to 28 times. Some sleeves were additionally exposed to moisturizers during their extension. Garment tension and dimensions were measured before and during the simulated wear and wash period to indicate each garment's ability to maintain its tension and therefore pressure throughout a period of "use." The results of the investigation were analyzed in groups where each group contained only 1 variable, thereby allowing the variables with the most significant impact on tension degradation to be identified. The investigation confirmed that all pressure garments lost tension and therefore pressure delivering ability over time and use. It further revealed that pressure garments designed to exert greater pressures degraded faster than those designed to exert lower pressures. Contact between pressure garments and moisturizers accelerated tension degradation, and machine-washing pressure garments tended to prolong their pressure-delivering properties compared with hand-washing them. To maintain the initial pressure delivered by pressure garments, powernet fabrics should be prestressed before being designed/constructed and they should be machine-washed by patients.
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