Malignant melanoma: social status and outdoor work

The incidence of, and mortality from, malignant melanoma of skin in whites are strongly influenced by socio-economic conditions. Professional and administrative workers have the highest rates of all. Clerks and salesmen have higher rates than skilled manual workers, who have higher rates than unskilled workers. Women, when classified by the occupation of their husbands, show a similar relationship to social status. The biases of incidence data from systems of cancer registration, and mortality data from death certificates are different, and the consistency of the data from different periods and from different populations suggests that the relationship is real. The bulk of the data is from Britain, but there is sufficient from the U.S. to indicate that the effect is not restricted to one country. No consistent increase in risk was found in outdoor workers compared with indoor workers of similar socio-economic status.     

Effect of cold work on stress corrosion cracking behavior of types 304 and 316 stainless steels

The influence of cold work (prestraining) in the range 2.3 to 56 pct on stress corrosion cracking (SCC) properties of types 304 and 316 stainless steels in boiling MgCl2 solution at 154 °C was investigated using a constant load method. In both materials, SCC initiation was in transgranular mode. Transition in stress corrosion cracking mode from transgranular to intergranular, as the crack proceeds, was observed at all cold work levels in 316 stainless steel and at cold work levels of 26 pct and 56 pct in 304 stainless steel. Both prestraining and increase in the initial applied stress facilitated the transition in crack morphology to intergranular mode. Increased tendency to intergranular SCC at high applied stresses and in cold worked specimens appears to be mechanistically analogous.     

Effect of cold work on stress corrosion cracking behavior of types 304 and 316 stainless steels

The influence of cold work (prestraining) in the range 2.3 to 56 pct on stress corrosion cracking (SCC) properties of types 304 and 316 stainless steels in boiling MgCl2 solution at 154 °C was investigated using a constant load method. In both materials, SCC initiation was in transgranular mode. Transition in stress corrosion cracking mode from transgranular to intergranular, as the crack proceeds, was observed at all cold work levels in 316 stainless steel and at cold work levels of 26 pct and 56 pct in 304 stainless steel. Both prestraining and increase in the initial applied stress facilitated the transition in crack morphology to intergranular mode. Increased tendency to intergranular SCC at high applied stresses and in cold worked specimens appears to be mechanistically analogous.     

Effect of cold work on hydrogen attack

A silicon killed 1020 steel was deformed to a maximum of 15 pct elongation in three point bending and exposed to hydrogen at 6.5 MPa and 450 °C for 44 to 220 h to develop hydrogen attack. In the undeformed material methane nucleated primarily on manganese sulphides and maganese silicate inclusions. With time fissures form along the entire length of the inclusions creating large fissures (>500 microns). Cold working the steel greatly enhanced the rate of fissure formation on the grain boundaries as well as the fraction of boundaries attacked. These fissures interconnect, venting methane to the surface. As a result of this venting the fissures in the deformed area swell much less and the material decarburizes at a more rapid rate than the undeformed. The degree of decarburization was independent the sign of the plastic strain. However, the direction of the fissures changed, being parallel to the free surface on the tensile side and perpendicular to the surface on the compressive side. The effect of cold work on HA was completely eliminated by an anneal at 650 °C for 1 h.     

Circulatory changes in cold-acclimation and cold stress

1. The cardiovascular changes of conscious cold-acclimated (CA) and warm-acclimated (WA) rats during exposure to 5 degrees C or 28 degrees C were studied. 2. The cardiac output, heart rate and stroke volume of Ca rats exposed to 5 degrees C and of WA rats during cold stress were significantly greater, and their calculated total peripheral resistance significantly less than those of WA rats ats exposed to 28 degrees C. These results show that circulatory changes participate in cold acclimation and cold stress. The circulatory changes in the two conditions were compared and the mechanism of the observed differences were discussed. 3. CA rats exposed to 28 degrees C showed a striking decrease of oxygen consumption and arterio-venous O2 difference, but significant circulatory changes were decreased heart rate and cardiac index only, indicating that the response was mainly metabolic.     

Structure transformation of alpha-brass subjected to cold work

X-ray evidence has been observed which indicates that a change from cubic to a hexagonal structure can occur in plastically deformed alpha-brasses. This transformation occurs only in the bulk of the material and not at the surface. The amount of deformation required to produce the transformation decreases for alloys containing lead. A model for the transformation is proposed. Calculated X-ray reflections of the proposed new hexagonal structure are consistent with the observed reflections.     

Optimised sintering route for cold work tool steels

Abstract

Two different powder metallurgy cold work tool steels, D7 and a nickel alloyed D7 modification, were compacted to full density by utilisation of super solidus liquid phase sintering in vacuum and nitrogen atmospheres. The experiments were carried out with respect to the fabrication of wear resistant metal matrix composites. These materials exhibit a higher durability than cast materials and are increasingly used in the mineral and mining industry. In the present paper, sintering exhibits a more cost effective processing of these materials compared with hot isostatic pressing. The experiments were supported by thermodynamic calculations with Thermo-Calc. Significant differences of the sintering behaviour in vacuum and nitrogen atmospheres were detected. Full density could be obtained at a sintering temperature as low as 1210°C.     

Relieving stress through value-rich work

On the basis of Herzberg, Mausner, and Snyderman's (1959) motivator-hygiene theory, it was hypothesized that intrinsic but not extrinsic work values would be inversely related to stress. Also investigated was the question of which work values provide the most relief from stress. Elementary school teachers and administrators (N = 607) from nine school boards in southern Ontario completed a survey that included Pines, Aronson, and Kafry's (1981) stress scale and Elizur's (1984) work values scale. Almost all of the 12 intrinsic work values investigated were negatively correlated with stress, but the 4 extrinsic work values studied were not consistently related to stress. Five work values explained 11% of the variance in physical stress, 9 work values explained 22% of the variance in emotional stress, and 6 work values explained 26% of the variance in mental stress. Four work values emerged as meaningful predictors of all three types of stress: being esteemed by others, achieving through work, doing meaningful work, and being able to use one's knowledge and abilities.     

Characterization of platelet hypofunctions in rats under SART stress (repeated cold stress)

Platelet hypoaggregability has been reported in rats exposed to a chronic form of environmental stress induced by long-lasting fluctuation in air temperature, known as SART (specific alternation of rhythm in temperature) stress. This study examines functional characteristics of platelets from stressed rats in more detail. Exposure to stress reduced aggregation and ATP release in platelets stimulated with collagen, as determined using platelet-rich plasma (PRP). The resting levels of ATP but not ADP in platelets from stressed rats were lower than those from unstressed ones. Collagen-induced release and resting level of serotonin also decreased in platelets from stressed rats. In contrast, stress failed to cause hypoaggregability of washed platelets. Circulating platelet aggregates were detected in stressed rats. From these data, SART stress appears to cause intravascular activation of platelets in spite of in vitro hypofunctions. Alteration in plasma milieu may be associated with stress-induced platelet hypofunctions in PRP.     

Assessment of hepatic viability during cold ischemic preservation

A reliable and easy method for assessing the viability of a cold ischemia-preserved donor liver prior to transplantation into the recepient is needed. Based on an earlier study, we hypothesized that liver free fatty acid (FFA) leakage into the preservation fluid may be a useful, atraumatic indicator of irreversible ischemic injury. The aim of the present study was to determine the time course and magnitude of liver FFA release into the preservation solution and its correlation with the duration of cold ischemic preservation compatible with survival after transplantation. Rat livers (n = 48) were flushed and preserved with University of Wisconsin (UW) solution at 4 degrees C for 0, 12, 24, and 48 h. Thereafter, half of the livers were analyzed for preservation fluid FFA (gas-liquid chromatography) and protein. The other half were perfused with Krebs-Henseleit (KH) solution at 37 degrees C for 1 h. Bile secretion and liver enzyme release (SGOT, SGPT, and LDH) were measured in addition to perfusate FFA and protein. Total FFA in the preservation fluid was 24 micrograms/g wet tissue after 12 h; it increased sharply 2.6-fold after 24 h and 3.7-fold after 48 h of preservation. Bile production was normal after 12 h of preservation but fell by 20% and 54% after 24 h and 48 h, respectively. LDH release rose from a value of 20 U/l at 0 time to 120 U/l and 260 U/l after 24 h and 48 h of preservation. These results suggest that liver viability declines sharply between 12 and 24 h of cold ischemic preservation, which corresponds with a sharp decrease in the 1-week survival from 100% to 33% after 12 h and 24 h, respectively, of cold ischemic preservation. We conclude that measuring FFA and LDH in the preservation solution of donor livers may be a useful means of assessing the quality of the cold-preserved liver before insertion into the recipient. We also speculate that a "threshold" FFA level in the UW preservation fluid indicating irreversible damage may be in the order of 35 micrograms total FFA/g liver. Studies on the clinical applicability of our findings are currently under way.     

Myocardial protection against cold stress with pravastatin

The CARE study showed that the myocardial infarction recurrence rate in patients with moderate cholesterol blood level decreases early during pravastatin treatment. Our goal is to evaluate the possible role of pravastatin in preventing the myocardial lesions induced by cold stress. Twenty Wistar-EPM rats were divided into four groups: Control (CON); PR (Pravastatin) treated with 10 mg/kg/d for 15 days; S (Stress group) in which the rats were submitted to cold stress (-8 degrees C for four hours); and PR + S group treated with pravastatin like PR group and also submitted to the cold stress. The animals were sacrificed and heart fragments were removed for optic and electronic microscopic analysis. The variable considered was mitochondria abnormality (edema, lyses and vacuolization) that was interpreted as crystolyses indices (CI) (n degree of abnormal mitochondria/n degree total of mitochondria). The following crystolyses indices, were found for each group respectively: CON, 2.0%; S, 95.5%; PR, 19.9% and PR + S group, 27.7%*(*p < 0.01). In conclusion, pravastatin prevented myocardial lesions induced by cold stress significantly.     

Predicting work stress compensation claims and return to work in welfare workers.

Occupational stress is prevalent in work areas in which there is high contact with distressed or dependent members of the public. However, little is known about the prediction and management of stress-related compensation claims, which can be expensive for employers. The authors interviewed all staff members of a large public sector welfare agency who had made a compensation claim for work-related stress during a 12-month period (N?=?19) and obtained in-depth information from 16 of the 17 who were still available. A clear relationship was found between type of stress precipitant and length of stress-related leave, suggesting that the organizational response to specific stressful incidents was much more effective than its response to chronic work stressors. Demographic data for all 19 claimants showed that they had taken twice as many days of sick leave as the organizational average in the year preceding their claim. There are important implications for personnel management practices that may reduce and prevent work stress for vulnerable workers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orientation and strain dependence of stored energy of cold work in axisymmetric copper

X-ray line broadening characterizations of the stored energy of cold work in axisymmetric OFHC copper rods has been studied as a function of crystallographic orientation and uniaxial strain level. The results were correlated with a path-averaged Taylor factor. As previously reported for plane-strain rolling, the stored energy of cold work is found to increase monotonically with increasing Taylor factor. This correlation is observed to hold over the entire range of strains studied, 0.092 ≤ ε≤ 0.367. Particle size separation of the Fourier line broadening coefficients indicates that particle size effects are dominant in OFHC copper at a strain level of 0.367. Formerly Graduate Student of Mechanical Engineering at Brigham Young University     

Effect of cold work on recrystallization behavior and grain size distribution in titanium

The effect of cold work in the range of 21.9 pct to 94.2 pct reduction in area by swaging on the recrystallization behavior and grain size distribution in Ti (0.2 pct O_eq) was investigated. In keeping with commonly observed behavior, increasing amounts of cold work lead to an increase in hardness prior to annealing and a decrease in the subsequent recrystallization temperature and grain size. Also, there occurred for the recrystallized grains a decrease in the standard deviation of the grain volume distribution In Σ_v deduced from the one-dimensional linear intercept measurements. The decrease in In Σ_v with cold work in swaged Ti is in good accord with that reported by Rhines and Patterson following uniaxial deformation of Al. Considering the results for both Al and Ti, it appears that the largest decrease in In Σ_v occurs for true strains up to R ~0.5, the change with larger strains being more gradual. The reason for the decrease in In Σ_v with increased cold work is not completely clear. The increased rate of grain growth with reduction in amount of cold work can be understood in terms of the larger number of three-edged grain faces which occur with the greater spread in the recrystallized grain volume distribution. Formerly a Graduate Student at The University of Kentucky Leave at NCSU from the Reactor Research Centre, Kalpakkam, India     

金属注射成形冷作工具钢的超声疲劳性能

用超声疲劳试验研究了金属注射成形(MIM)冷作工具钢和锻轧钢(JIS SKD11)的高周疲劳性能。锻轧钢试样于423K回火1h。另一方面，为了评估回火温度对疲劳性能的影响，将MIM钢试样于不同温度下进行了回火。在N=103～108疲劳寿命范围内进行了超声疲劳试验。MIM钢试样的疲劳强度和锻轧钢试样相同。MIM钢试样的疲劳强度随着回火温度升高而减低。显微组织的观察结果表明，MIM钢试样的碳化物的直径与形状比锻轧钢试样的均一。     

多参数耦合下冷轧铝带工作辊分段冷却调节特性

为得到多参数耦合下冷轧铝带工作辊分段冷却调节特性,建立了工作辊和轧件的一体化耦合传热模型.耦合传热建模过程包含工作辊和轧件导热微分方程的建立、轧件变形热和摩擦热的求解、换热边界条件的确立、工作辊热辊形的计算及采用二维交替差分对微分方程进行求解.仿真结果表明,同一轧制参数下工作辊分段冷却正负方向调节能力近似相等,但单向调节幅度受轧制参数影响较大,轧制长度、喷射梁工作压力和摩擦系数的增加对分段冷却调控能力具有促进作用,轧制速度的作用则相反.     

Introduction to the measurement of stress at work

OBJECTIVE: To determine the optimal postion for plate fixation in complex fractures of the proximal radius in which head and neck dissociation occurs. DESIGN: Technical study. SETTING: Tertiary referral center, teaching hospital, U.S. military. SUBJECTS: Five preserved cadavers. MAIN OUTCOME MEASURE: Radioulnar impingement and proximity to neurovascular structures were directly measured in elbows plated in each of three positions: neutral, full pronation, and full supination. RESULTS: Application of the 2.0-millimeter T-plate to the lateral aspect of the radial head and neck with the forearm in neutral position had no impingement, whereas application in full pronation resulted in loss of the last 30 degrees of supination. Plate application in full supination resulted in the loss of the last 10 degrees of pronation. In addition, there was no impingement when the 2.7-millimeter plate was applied similarily in the neutral position. None of these positions resulted in increased risk to neurovascular structures. CONCLUSIONS: The optimal position for plate fixation of complex proximal radius fractures is with the forearm in neutral position, with the plate applied directly lateral. A larger implant, 2.7 millimeters, may be used if this technique is followed without further risk of impingement and loss of motion.