28,196 research outputs found

    Corrosion Damage Analysis and Material Characterization of Sherman and Centaur - The Historic Military Tanks

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    A study of corrosion damage and material characterization of two historic military tanks, the Sherman and Centaur is reported. Experiments were conducted to analyse surface corrosion and corrosion propagation from surface to sub-surface. Significant surface corrosion was found, this phenomenon was further facilitated by delamination failure mechanisms. Corrosion depth for the Sherman was approximately 110 µm, where sulphide inclusions were detected in the sub-surface analysis. The Centaur’s analysis showed corrosion pits at 100 µm depth. These pits possess random geometrical configurations with evidence of sulfur, sodium and calcium

    Increased prevalence of precancerous changes in relatives of gastric cancer patients: critical role of H. pylori

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    Background & Aims:Helicobacter pylori is believed to predispose to gastric cancer by inducing gastric atrophy and hypochlorhydria. First-degree relatives of patients with gastric cancer have an increased risk of developing gastric cancer. The aim of this study was to determine the prevalence of atrophy and hypochlorhydria and their association with H. pylori infection in first-degree relatives of patients with gastric cancer. Methods:H. pylori status, gastric secretory function, and gastric histology were studied in 100 first-degree relatives of patients with noncardia gastric cancer and compared with those of controls with no family history of this cancer. Results: Compared with healthy controls, relatives of patients with gastric cancer had a higher prevalence of hypochlorhydria (27% vs. 3%) but a similar prevalence of H. pylori infection (63% vs. 64%). Relatives of cancer patients also had a higher prevalence of atrophy (34%) than patients with nonulcer dyspepsia (5%) matched for H. pylori prevalence. Among the relatives of cancer patients, the prevalence of atrophy and hypochlorhydria was increased only in those with evidence of H. pylori infection, was greater in relatives of patients with familial cancer than in relatives of sporadic cancer index patients, and increased with age. Eradication of H. pylori infection produced resolution of the gastric inflammation in each subject and resolution of hypochlorhydria and atrophy in 50% of the subjects. Conclusions: Relatives of patients with gastric cancer have an increased prevalence of precancerous gastric abnormalities, but this increase is confined to those with H. pylori infection. Consequently, prophylactic eradication of the infection should be offered to such subjects

    The Effects of Heat Exposure During Intermittent Exercise on Physical and Cognitive Performance Among Team Sport Athletes.

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    This study investigated the effects of heat exposure on physical and cognitive performance during an intermittent exercise protocol so as to reflect the incremental fatigue experienced during team sports. Twelve well-trained male team sport players completed an 80-minute cycling intermittent sprint protocol (CISP), alongside computerized vigilance and congruent (i.e., simple) and incongruent (i.e., complex) Stroop tasks of cognitive functioning, in two counterbalanced temperature conditions; hot (32°C[50%rh]) and control (18°C[50%rh]). Incongruent Stroop accuracy declined over time (p = .002), specifically in the second (Mdiff = -3.75, SD = 0.90%, p = .009) and third (Mdiff = -4.58, SD = 1.22%, p = .019) quarters compared to the first quarter of the CISP; but there were no differences between temperature conditions. Congruent Stroop reaction time (RT) was quicker in the second quarter of exercise in the hot condition (M = 561.99, SD = 112.93 ms) compared to the control condition (M=617.80, SD = 139.71 ms; p = .022), but no differences were found for congruent Stroop accuracy nor vigilance measures. Additionally, peak power output was lower during the third quarter of the CISP in the hot condition (M = 861.31, SD = 105.20 W) compared to the control condition (M = 900.68, SD = 114.84 W; p < .001). Plasma normetanephrine and metanephrine concentrations increased from pre- to post-CISP (Mdiff = +616.90, SD = 306.99, p < .001; and Mdiff = +151.23, SD = 130.32, p = .002, respectively), with a marginal interaction suggesting a higher normetanephrine increase from pre- to post-CISP in the hot versus the control condition (p = .070). Our findings suggest that accuracy for more complex decisions suffered during prolonged high-intensity intermittent exercise, perhaps due to exercise-induced catecholamine increases. Athletes may have also reduced physical effort under increased heat exposure, indicating how cognitive performance may be sustained in physically demanding environments

    Regioselective chlorination of phenols in the presence of tetrahydrothiopyran derivatives

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    Four six-membered cyclic sulfides, namely tetrahydrothiopyran, 3-methyltetrahydrothiopyran, 4-methyltetrahydrothiopyran and 4,4-dimethyltetrahyrdrothiopyran have been used as moderators in chlorination reactions of various phenols with sulfuryl chloride in the presence of aluminum or ferric chloride. On chlorination of phenol, ortho-cresol and meta-cresol the para/ortho chlorination ratios and yields of the para-chloro isomers are higher than when no cyclic sulfide is used for all of the cyclic sulfides, but chlorination of meta-xylenol is less consistent, with some cyclic sulfides producing higher p/o ratios and others producing lower ratios than reactions having no sulfide present

    In the beginning: Role of autonomy support on the motivation, mental health and intentions of participants entering an exercise referral scheme

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    Self-determination theory (Deci & Ryan, 2000, Intrinsic motivation and self-determination in human behaviour. New York: Plenum Publishing) highlights the impact autonomy supportive environments can have on exercise motivation and positive health outcomes. Yet little is known about whether differential effects occur as a function of which significant other is providing this support. Further, no research has examined the relationship between motivation and the social environment with participants’ mental health and intentions to be physically active before entering an exercise intervention. Study participants were 347 British adults who were about to start an exercise referral scheme. Regression analyses revealed that the effects of autonomy support on mental health and physical activity intentions differed as a function of who provided the support (offspring, partner or physician), with the offspring having the weakest effects. A structural model was supported, indicating that autonomy support and more autonomous regulations led to more positive mental health outcomes and stronger intentions to be physically active. Knowledge of the social environmental and personal motivation of those about to commence an exercise programme can provide important insights for professionals supporting such efforts
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