• Clinical and Experimental Pediatrics
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• v.49 no.5
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• pp.565-569
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• 2006

Rothmund-Thomson syndrome (RTS), is a rare autosomal recessive disorder, characterized by : skin photosensitivity, poikiloderma, sparse hair, sparse eyebrows/lashes, short stature, skeletal abnormalities, cataracts, and an increased risk of malignancy. Skeletal abnormalities include : dysplasia, absent or malformed bones, such as absent radii, osteopenia, and delayed bone formation. RTS is thought to result from chromosomal instability, and children with RTS are at risk of cancer. Reported cancers in children with RTS include : basal cell carcinoma, squamous cell carcinoma of the skin and osteosarcoma of bone. We report an 11 year-old boy, who presented to our institution with poikilodermatous skin change with telangiectasia and hyperpigmentation, absence of radius and thumb, and the development of osteosarcoma of the left tibia. The patient is now receiving supportive care and is receiving maintenance chemotherapy after surgery for osteosarcoma.

• Journal of Mechanical Science and Technology
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• v.20 no.6
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• pp.738-747
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• 2006

The friction behaviour of Si-wafer, diamond-like carbon (DLC) and two self-assembled monolayers (SAMs) namely dimethyldichlorosilane (DMDC) and diphenyl-dichlorosilane (DPDC) coated on Si-wafer was studied under loading conditions in milli-newton (mN) range. Experiments were performed using a ball-on-flat type reciprocating micro-tribo tester. Glass balls with various radii 0.25 mm, 0.5 mm and 1 mm were used. The applied normal load was in the range of 1.5 mN to 4.8 mN. Results showed that the friction increased with the applied normal load in the case of all the test materials. It was also observed that friction was affected by the ball size. Friction increased with the increase in the ball size in the case of Si-wafer. The SAMs also showed a similar trend, but had lower values of friction than those of Si-wafer In-terestingly, for DLC it was observed that friction decreased with the increase in the ball size. This distinct difference in the behavior of friction in DLC was attributed to the difference in the operating mechanism. It was observed that Si-wafer and DLC exhibited wear, whereas wear was absent in the SAMs. Observations showed that solid-solid adhesion was dominant in Si-wafer, while plowing in DLC. The wear in these two materials significantly Influenced their friction. In the case of SAMs their friction behaviour was largely influenced by the nature of their molecular chains.