The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite cons...The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in a-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al2O3, SiO2, TiO2 and α-Ti. The average microhardness of the composite （matrix） varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti-6Al-4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl （mass fraction） solution shows that corrosion potential （φcorr） shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti-6Al-4V alloy.展开更多
Background.The British Association of Dermatologists(BAD)has produced guidelines for management of basal cellcarcinoma(BCC)in the UK.Objectives.Our primary objectives were to assess the management of BCCs in Scotland ...Background.The British Association of Dermatologists(BAD)has produced guidelines for management of basal cellcarcinoma(BCC)in the UK.Objectives.Our primary objectives were to assess the management of BCCs in Scotland and to compare it with BAD guidelines.Our secondary objectives were to audit waiting times and referral patterns.Methods.In phase I of the aud it,dermatologists in 14 centres across Scotl and prospectively registered demographic and clinical data of all lesions suspected to be BCCs over a 6-week period between October and December 2000.In phase II,details of management of these lesions were evaluated by case note review.Results.Of the 48 consultant dermatologists contacted,42 took part in the survey.There were 524 clinically suspected BCCs seen in 470 patients;164 lesions in 146 patients showed pathology other than BCC and were excluded from analysis,thus leaving 360 lesions available for analysis.There was wide variation in waiting times among Scottish dermatology centres.BCCs were equally distributed between the sexes,and lesions most commonly presented in those aged 71-80 years.A diagnostic biopsy was taken in 22%of lesions,and the rest were treated definitively after a clinical diagnosis of BCC,of which 90%were confirmed on histology.Nodulocystic lesions were the most common type of tumour,comprising 48%of lesions,and most BCCs were located on the head and neck region.Correlation of the histological type of BCC and treatment received showed that nodulocystic and morpheic BCCs were managed as recommended.There were more superficial BCCs treated with surgical excision than expected(22 of 34 lesions).Four of 21 recurrent tumours and 9 of 81 tumours on high-risk areas of the face were managed with curettage and cautery or cryotherapy,rather than surgical excision.Of the 297 excised tumours,25(9%)were incompletely excised.All the high-risk tumours and incompletely excised tumours were offered follow-up in the dermatology clinics.Conclusions.In general,BCCs are managed according to BAD guidelines in Scotland,but waiting times vary considerably.展开更多
基金Financial supports from various funding agencies Tata Steel, Jamshedpur, Department of Science and Technology, New Delhi, Council of Scientific and Industrial Research, New Delhi and Board of Research on Nuclear Science, Bombay for the present study are gratefully acknowledged
文摘The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in a-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al2O3, SiO2, TiO2 and α-Ti. The average microhardness of the composite （matrix） varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti-6Al-4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl （mass fraction） solution shows that corrosion potential （φcorr） shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti-6Al-4V alloy.
文摘Background.The British Association of Dermatologists(BAD)has produced guidelines for management of basal cellcarcinoma(BCC)in the UK.Objectives.Our primary objectives were to assess the management of BCCs in Scotland and to compare it with BAD guidelines.Our secondary objectives were to audit waiting times and referral patterns.Methods.In phase I of the aud it,dermatologists in 14 centres across Scotl and prospectively registered demographic and clinical data of all lesions suspected to be BCCs over a 6-week period between October and December 2000.In phase II,details of management of these lesions were evaluated by case note review.Results.Of the 48 consultant dermatologists contacted,42 took part in the survey.There were 524 clinically suspected BCCs seen in 470 patients;164 lesions in 146 patients showed pathology other than BCC and were excluded from analysis,thus leaving 360 lesions available for analysis.There was wide variation in waiting times among Scottish dermatology centres.BCCs were equally distributed between the sexes,and lesions most commonly presented in those aged 71-80 years.A diagnostic biopsy was taken in 22%of lesions,and the rest were treated definitively after a clinical diagnosis of BCC,of which 90%were confirmed on histology.Nodulocystic lesions were the most common type of tumour,comprising 48%of lesions,and most BCCs were located on the head and neck region.Correlation of the histological type of BCC and treatment received showed that nodulocystic and morpheic BCCs were managed as recommended.There were more superficial BCCs treated with surgical excision than expected(22 of 34 lesions).Four of 21 recurrent tumours and 9 of 81 tumours on high-risk areas of the face were managed with curettage and cautery or cryotherapy,rather than surgical excision.Of the 297 excised tumours,25(9%)were incompletely excised.All the high-risk tumours and incompletely excised tumours were offered follow-up in the dermatology clinics.Conclusions.In general,BCCs are managed according to BAD guidelines in Scotland,but waiting times vary considerably.
