910 resultados para Rockwell Superficial Hardness Tester


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More than 3000 years ago, men began quenching and tem­pering tools to improve their physical properties. The an­cient people found that iron was easier to shape and form in a heated condition. Charcoal was used as the fuel, and when the shaping process was completed, the smiths cooled the piece in the most obvious way, quenching in water. Quite un­intentionally, these people stumbled on the process for im­proving the properties of iron, and the art of blacksmithing began.

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In this research the taxonomic structure of diatoms in sediments of high mountain lakes was studied. These lakes are located in Chile between 32°49' and 38°48' S in the Andean Cordillera. A total of 99 diatom taxa distributed in 48 genera were identified and all this taxa are cosmopolitan excepting a Eunotia andinofrequens, Gomphonema punae, Pinnularia araucanensis and Pinnularia acidicola, which are know only for the Southern Hemisphere. The assemblages of diatoms were different in the studied lakes. So the high mountain lakes Ocho, Huifa, Ensueño and Negra, dominated benthic diatoms which are typical of oligotrophic and acid waters as Achnanthidium exiguum, Achnanthidium minutissimum, Encyonema minutum, Pinnularia acidicola and Planothidium lanceolatum. In the assemblages from lakes Galletué, Icalma and Laja planktonic diatoms were more abundant, which are common in alkaline and mesotrophic waters, e.g., Asterionella formosa, Aulacoseira distans, Aulacoseira granulata, Cyclotella stelligera and Rhopalodia gibba.

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BACKGROUND Although superficial thrombophlebitis of the upper extremity represents a frequent complication of intravenous catheters inserted into the peripheral veins of the forearm or hand, no consensus exists on the optimal management of this condition in clinical practice. OBJECTIVES To summarise the evidence from randomised clinical trials (RCTs) concerning the efficacy and safety of (topical, oral or parenteral) medical therapy of superficial thrombophlebitis of the upper extremity. SEARCH METHODS The Cochrane Vascular Group Trials Search Co-ordinator searched the Specialised Register (last searched April 2015) and the Cochrane Register of Studies (2015, Issue 3). Clinical trials registries were searched up to April 2015. SELECTION CRITERIA RCTs comparing any (topical, oral or parenteral) medical treatment to no intervention or placebo, or comparing two different medical interventions (e.g. a different variant scheme or regimen of the same intervention or a different pharmacological type of treatment). DATA COLLECTION AND ANALYSIS We extracted data on methodological quality, patient characteristics, interventions and outcomes, including improvement of signs and symptoms as the primary effectiveness outcome, and number of participants experiencing side effects of the study treatments as the primary safety outcome. MAIN RESULTS We identified 13 studies (917 participants). The evaluated treatment modalities consisted of a topical treatment (11 studies), an oral treatment (2 studies) and a parenteral treatment (2 studies). Seven studies used a placebo or no intervention control group, whereas all others also or solely compared active treatment groups. No study evaluated the effects of ice or the application of cold or hot bandages. Overall, the risk of bias in individual trials was moderate to high, although poor reporting hampered a full appreciation of the risk in most studies. The overall quality of the evidence for each of the outcomes varied from low to moderate mainly due to risk of bias and imprecision, with only single trials contributing to most comparisons. Data on primary outcomes improvement of signs and symptoms and side effects attributed to the study treatment could not be statistically pooled because of the between-study differences in comparisons, outcomes and type of instruments to measure outcomes.An array of topical treatments, such as heparinoid or diclofenac gels, improved pain compared to placebo or no intervention. Compared to placebo, oral non-steroidal anti-inflammatory drugs reduced signs and symptoms intensity. Safety issues were reported sparsely and were not available for some interventions, such as notoginseny creams, parenteral low-molecular-weight heparin or defibrotide. Although several trials reported on adverse events with topical heparinoid creams, Essaven gel or phlebolan versus control, the trials were underpowered to adequately measure any differences between treatment modalities. Where reported, adverse events with topical treatments consisted mainly of local allergic reactions. Only one study of 15 participants assessed thrombus extension and symptomatic venous thromboembolism with either oral non-steroidal anti-inflammatory drugs or low-molecular-weight heparin, and it reported no cases of either. No study reported on the development of suppurative phlebitis, catheter-related bloodstream infections or quality of life. AUTHORS' CONCLUSIONS The evidence about the treatment of acute infusion superficial thrombophlebitis is limited and of low quality. Data appear too preliminary to assess the effectiveness and safety of topical treatments, systemic anticoagulation or oral non-steroidal anti-inflammatory drugs.

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It has recently been reported in this journal that local fat depots produce a sizable frequency-dependent signal attenuation in magnetic resonance spectroscopy (MRS) of the brain. If of a general nature, this effect would question the use of internal reference signals for quantification of MRS and the quantitative use of MRS as a whole. Here, it was attempted to verify this effect and pinpoint the potential causes by acquiring data with various acquisition settings, including two field strengths, two MR scanners from different vendors, different water suppression sequences, RF coils, localization sequences, echo times, and lipid/metabolite phantoms. With all settings tested, the reported effect could not be reproduced, and it is concluded that water referencing and quantitative MRS per se remain valid tools under common acquisition conditions.

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The objective of this study was to determine the impact of different follow-up cystoscopy frequencies on time to development of invasive bladder cancer in a cohort of 3,658 eligible patients 65 and older with an initial diagnosis of superficial bladder cancer between 1994 and 1998. Bladder cancer patients in the Surveillance, Epidemiology, and End Results (SEER)-Medicare database were used as the study population. ^ It was hypothesized that superficial bladder cancer patients receiving less frequent cystoscopy follow-up would develop invasive bladder cancer sooner after initial diagnosis and treatment than patients seen more frequently for cystoscopy follow-up. Cox Proportional Hazard Regression revealed that patients seen for cystoscopy every 3 or more months were 83–89% less likely to develop invasive cancer than patients seen every 1 to 2 months. A comparison of the 2 groups (1 to 2 months vs. 3≥ months) revealed that the 1 to 2 month group may have had more aggressive disease, and they are seen more frequently as a result. ^ These findings suggest that there are two groups of superficial bladder cancer patients: those at high risk of developing invasive bladder cancer and those at low risk. Patients who developed invasive bladder cancer sooner after initial diagnosis and treatment were seen more frequently for cystoscopy follow-up. The recommendation is that cystoscopy should be based on disease status at 3 months. Standardized schedules give all patients the same number of cystoscopies regardless of their risk factors. This could lead to unnecessary cystoscopies in low risk patients, and fewer than optimal cystoscopies in high risk patients. ^

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Fil: Fornessi, Román. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Fil: Fornessi, Román. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Fil: Carbajo, María Rosa. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Fil: Carbajo, María Rosa. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Fil: Fornessi, Román. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Fil: Fornessi, Román. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.