Modeling of wear resistance for TC21 Ti-alloy using response surface methodology.

This study investigated the effect of heat treatment processes on the dry sliding wear resistance of the TC21 Ti-alloy at several levels of normal load and sliding speed. Response Surface Methodology (RSM) has been used as a design of the experiment procedure. OM and FESEM besides XRD analysis were used for results justification. Highest hardness of 49 HRC was recorded for WQ + Aging specimens due to the plenty of α″ which decomposed to αs and the more αs, while the lowest hardness of 36 HRC was reported for WQ specimens. The results revealed that specimens subjected to water quenching and aging (WQ + Aging) under extreme load and speed conditions (50 N and 3 m/s), possessed the poorest wear resistance although they had the highest hardness. While those left in the annealed condition revealed the highest wear resistance although they had much lower hardness when compared to other conditions. A mathematical polynomial model for wear resistance expressed in wear rate was developed, validated then used to get the optimum parameters.

Three-dimensional kinematic analysis of the second through fifth carpometacarpal joints.

The kinematics of the 2nd through 5th carpometacarpal (CMC) joints was investigated by using a 3-dimensional dynamic motion analysis system to delineate flexion-extension motion, radial-ulnar deviation, and pronation-supination motion. Analysis of the axes of rotation revealed that the axes of rotation for flexion-extension motion are located within the base of each respective metacarpal bone. The axis of rotation for radial-ulnar deviation passes through the distal carpal bone of each CMC joint except in the 3rd CMC joint where the axis of rotation is located within the base of the 3rd metacarpal. The axis of rotation for pronation-supination motion passes through the base of the respective metacarpal except in the 3rd CMC joint where it is located within the hamate. The overall flexion-extension motions of the 2nd and 3rd carpometacarpal (CMC) joints were found to be more limited than those of the 4th and 5th CMC joints (11 degrees, 7 degrees to 20 degrees, 27 degrees, respectively) and even more so in radial-ulnar deviation (2 degrees, 4 degrees to 7 degrees, 13 degrees, respectively) and pronation-supination motion (5 degrees, 5 degrees to 27 degrees, 22 degrees, respectively). The 5th CMC joint has the greatest overall range of motion with the flexion-extension motion found to be greatly reduced by 40% to 28 degrees when the 4th CMC joint was immobilized. Maximum range of motion in flexion-extension of the 5th CMC joint is dependent on and contributed by the 4th CMC joint motion.

A study of peristomal recurrence.

This is a retrospective and a prospective study of 435 laryngectomized patients at the department of Otolaryngology, Cairo University, between 1987 and 1997. The authors analyze the data of 26 patients who returned with peristomal recurrence. A statistical analysis was performed to determine the correlation between peristomal recurrence, and the site of the primary tumor, its stage, the presence of nodal metastases and the performance of an emergency tracheostomy more than 48 hours before surgery. In this study, peristomal recurrence occurred in about 6% of our laryngectomized patients. A significant correlation was found between peristomal recurrence and the involvement of the subglottic area, T4 stage of the primary tumor and nodal metastases. No correlation was found between peristomal recurrence and emergency tracheostomy.

Rhabdomyosarcoma of head and neck in children.

Embryonal rhabdomyosarcoma is a rare condition that tends to occur in the head and neck in children. This disease carried a very poor prognosis until 10 years ago when a multidisciplinary approach (with surgery, therapy and multiple drug chemotherapy) was instituted. In this article a review of the literature on embryonal rhabdomyosarcoma is given and three rare cases have been reported; the first involved the palate, the second affected the ear and mastoid, and the third was a case originating in the nasopharynx with orbital involvement. Clinical and histopathological descriptions are given and the results of therapy are evaluated.

Leprosy of the upper respiratory tract. A clinical bacteriological, histopathological and histochemical study of twenty cases.

Twenty cases clinically diagnosed as leprosy were thoroughly examined for E.N.T. lesions. These lesions were subjected to bacteriological, histopathological and histochemical studies. The results have been tabulated and discussed with special stress on some findings which are of help in diagnosing the disease.