Experimental Investigation of Engine Valve Train Friction Considering Effects of Operating Conditions and WPC Surface Treatment.

Reduction in friction ensures fuel economy, control on emissions and durability of components in internal combustion engines. A modern gasoline internal combustion engine was instrumented to determine the friction values at the cam-roller interface considering the effects of surface treatment and engine operating state. A series of tests under different operating speeds and lubricant inlet temperatures were undertaken using both an original surface roller and a Wonder Process Craft (WPC) surface-treated engine roller. The results clearly revealed a substantial reduction in friction magnitude for the WPC surface-treated engine roller in comparison to the original roller while operating under similar conditions, indicating their strong potential for employment in engines. An increase in friction with the rise in temperature was also observed for both types of rollers, whereas increased lubricant entraining velocity due to higher operating speed had the opposite impact. A considerable reduction in frictional drive torque ranging from 8% to 28% was observed by employing the WPC-treated roller in comparison to original/untreated roller at various operating conditions, which signifies the strong potential for employment of WPC surface treatment in the roller/follower valve train engines.

Spontaneous Midsubstance Rupture of the Flexor Digitorum Profundus Tendon of the Long Finger.

Closed flexor tendon injuries can often result from trauma that causes sudden forceful extension of an actively flexed digit. These closed tendon injuries commonly occur as avulsions in flexor zone I. Spontaneous midsubstance flexor tendon ruptures are rare, especially in the absence of an underlying pathology. Diagnosing such injuries accurately is challenging and critical. We present a case of a zone III spontaneous flexor tendon rupture of the long finger after forceful eccentric loading. Surgical exploration was performed, and the level of the rupture was identified during surgery. A side-to-side tendon repair technique was performed using a palmaris longus tendon graft. No underlying pathology to explain the rupture was found in this case. This report emphasizes the importance of considering spontaneous midsubstance ruptures, identifying the level of ruptures, and preoperative planning for such cases. It reviews the possible causes and treatment of spontaneous flexor tendon rupture.

Mandibular Myofibroma and Severe Trismus: A Complex Case and Review of Complications.

A female child was investigated for insidious onset of temporomandibular joint dysfunction and trismus in the setting of a mandibular myofibroma. Myofibromas, benign mesenchymal neoplasms composed of spindle cells, are rarely found in the oral cavity, most commonly in the mandible. These lesions are historically described as indolent with a high cure rate and minimal recurrence rates following surgical resection. The patient initially presented with concerns regarding snoring, retrognathia, and jaw ankylosis, as well as a history of trouble latching as an infant but without obvious physical deformities. Imaging revealed a large expansile lytic mass of the mandible, but no temporomandibular joint involvement; surgical biopsy evidenced myofibroma, and the lesion was resected. Over the course of disease, the lesion continued to expand, and the patient's maximal incisal opening continued to decrease despite conservative management with jaw physiotherapy; eventually she could not open her mouth despite the absence of joint involvement. Re-exploration along with formal jaw physiotherapy was achieved and optimal jaw opening was maintained. Myofibromas are rare benign desmoid tumors that can present anywhere in the body in solitary and multicentric forms, and previously did not present significant challenges to surgical and medical management. Tumors of the mandible may present with trismus and soft tissue ankylosis, which can mimic temporomandibular joint dysfunction in the absence of joint involvement. Physical therapy, rehabilitation, and soft tissue contracture release are key to management and improving outcomes in oral cancer patients, regardless of tumor pathology.

Severe Cherubism Treated with Curettage, Osteotomy, and Bony Repositioning: A Case Series of Three Patients.

Cherubism is a rare, autosomal dominant condition characterized by the replacement of medullary bone by fibro-osseous lesions, predominantly in the bilateral maxillae and/or mandibles. The clinical presentation of cherubism can vary widely, from clinically undetectable to severe facial disfigurement. Although there are no established management guidelines for this condition, conservative management with observation is typically favored in most cases due to the possibility of spontaneous regression following puberty. In this article, we present three cases of moderate to severe cherubism managed with early surgical intervention utilizing curettage and osteotomy followed by bony repositioning. We aimed to show the feasibility and safety of this minimally invasive surgical technique in the management of moderate to severe cases of cherubism to provide improvement in patient quality of life, aesthetics, and function while also possibly mitigating the need for later reconstructive surgery.

A Custom Stabilizing Splint for the Management of BLCP with Protruding Premaxilla.

A severely protruding premaxilla in a patient with bilateral cleft lip and palate prevents functional closure of the orbicularis oris muscle and acceptable reconstruction of the nasolabial components during primary cheiloplasty. This is typically corrected with vomerine osteotomy and premaxillary setback, followed by cheiloplasty and rhinoplasty. Due to the risk of vascular compromise to the prolabium and premaxillary segment, the lip and nose repair is often staged after the vomerine osteotomy and premaxillary setback has healed. Stabilizing the premaxillary segment to allow adequate healing has been a topic of interest. Several methods have been described, but each is associated with varying degrees of compromise of the blood supply to the premaxilla. To combat this, the authors created a custom oral splint that effectively maintained the position of the premaxilla with minimal impingement of the blood supply. The authors present two cases in which a two-stage premaxillary setback with a custom-stabilizing oral splint was performed, followed by primary cheiloplasty and rhinoplasty in an age-appropriate and delayed presentation of bilateral cleft lip and palate and protruding premaxilla.

A Review of Friction Performance of Lubricants with Nano Additives.

It has been established in literature that the addition of nanoparticles to lubricants at an optimum concentration results in a lower coefficient of friction compared to lubricants with no nanoparticle additives. This review paper shows a comparison of different lubricants based on the COF (coefficient of friction) with nanoadditives. The effect of the addition of nanoparticles on the friction coefficient was analyzed for both synthetic and biolubricants separately. The limitations associated with the use of nanoparticles are explained. The mechanisms responsible for a reduction in friction when nanoparticles are used as an additive are also discussed. Various nanoparticles that have been most widely used in recent years showed good performance within lubricants, including CuO (copper oxide), MoS2 (molybdenum disulfide), and TiO2 (titanium dioxide). The paper also indicates some research gaps that need to be addressed.

Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines.

The environmental concerns associated with artificially formulated engine oils have forced a shift towards bio-based lubricants. The deposition of hard coatings on engine components and migrating to environmentally friendly green lubricants can help in this regard. Chemically modified forms of vegetable oils, with better low-temperature characteristics and enhanced thermo-oxidative stability, are suitable substitutes to conventional lubricant base oils. The research presented in this manuscript was undertaken to experimentally investigate the wear and friction performance of a possible future generation of an environmentally friendly bio-based lubricant as a potential replacement for conventional engine lubricants. In order to quantify the tribological benefits which can be gained by the deposition of DLC coatings, (an (a-C:H) hydrogenated DLC coating and an (a-C:H:W) tungsten-doped DLC coating) were applied on the cam/tappet interface of a direct acting valve train assembly of an internal combustion engine. The tribological correlation between DLC-coated engine components, lubricant base oils and lubricant additives have been thoroughly investigated in this study using actual engine operating conditions. Two additive-free base oils (polyalphaolefines (PAO) and chemically-modified palm oil (TMP)) and two multi-additive-containing lubricants were used in this investigation. Real-time drive torque was measured to determine the friction force, detailed post-test analysis was performed, which involved the use of a specialized jig to measure camlobe wear. An optical profilometer was used to measure the wear on the tappet, high-resolution scanning electron microscopy was employed to study the wear mechanism and energy-dispersive X-ray spectroscopy was performed on the tested samples to qualitatively access the degradation of the coating. When using additive-free TMP, a low friction coefficient was observed for the cam/tappet interface. The presence of additives further improved the friction characteristics of TMP, resulting in reduced average friction torque values. A tremendous enhancement in wear performance was recorded with a-C:H-coated parts and the coating was able to withstand the test conditions with little or no delamination.

Risk factors of stroke in Pakistan: a dedicated stroke clinic experience.

BACKGROUND: Secondary prevention of cerebrovascular disease through dedicated stroke clinics has been shown to decrease recurrent vascular events in patients. However, there is limited literature describing such stroke clinic experiences from low and middle income countries. This study describes patient characteristics and observations made at the first systematized stroke clinic in Pakistan. METHODS: A retrospective audit of medical records of all patients presenting between September 2006 and August 2008 with a cerebrovascular event was conducted. Information about clinical presentation, modifiable risk factors and laboratory and radiological investigations was collected. Burden of disability was assessed using Modified Rankin score. Data was entered and analyzed using SPSS 14.0. RESULTS: 159 patients with a mean age of 57.0 +/- 13.9 years were included in this study and 34.6% of all patients were women. 108 patients were diagnosed with ischemic stroke (67.9%) while 34 patients presented with hemorrhagic stroke (21.4%) and 17 patients presented with transient ischemic attacks (10.7%). Hypertension was the most common modifiable risk factor seen in 78.0%, followed by diabetes in 40.3% and dyslipidemia in 31.5%. At presentation to clinic, only 26.0% patients with dyslipidemia and 64.5% patients with hypertension were on appropriate medications. CONCLUSION: A high prevalence of modifiable risk factors such as hypertension in stroke patients was observed and it presents an opportunity for conventional interventions in Pakistan. Systematized clinics for stroke and an algorithmic approach in primary care towards stroke may improve the implementation of evidence based secondary prevention strategies in developing countries.

Knowledge, attitudes and practices regarding dengue fever among adults of high and low socioeconomic groups.

OBJECTIVE: To ascertain the knowledge, attitudes and practices of selected adult population in Pakistan regarding Dengue Fever. METHODS: A cross sectional survey was conducted among selected communities with different socio-economic backgrounds in Karachi, Pakistan. A sample size of 440 adults (aged 18 years and above) were interviewed using a pre-tested questionnaire regarding their knowledge, attitude and practices about dengue fever. A composite scoring system, based on the answers given in the questionnaire, was used to establish the level of awareness in the population. The division of the higher and lower socio-economic groups was based on their income and locality; both these variables were determined as a part of our survey. RESULTS: Data from 400 respondents (244 males, 156 females) was used for primary analysis. About thirty five percent of the sample had adequate knowledge about dengue fever and its vector. Knowledge had significant associations with education (p = 0.004) and socioeconomic status (p = 0.02). The high socioeconomic group showed better preventive practices. CONCLUSION: Knowledge of dengue is inadequate in the low socioeconomic class. Better preventive practices against the vector are prevalent in the high socioeconomic group. Hence, a greater focus should be accorded to the low socioeconomic areas in future health campaigns.

Recurrent Desmoid Tumor with Intra-Abdominal Extension After Abdominoplasty: A Rare Presentation.

BACKGROUND Desmoid tumors are fibrous neoplasms that originate from the musculoaponeurotic structures in the body. Abdominal wall desmoid tumors are rare, but they can be locally aggressive, with high incidence of recurrence. These tumors are more common in young, fertile women. They frequently occur during or after pregnancy. CASE REPORT We present the case of a 63-year-old post-menopausal woman with a desmoid tumor of the anterior abdominal wall. She had no relevant family history. During abdominoplasty, an incidental mass was excised and biopsied, and was identified as a desmoid tumor with free margins. One year later, the patient presented with vague abdominal discomfort and feeling of heaviness. An incision was made through the previous abdominoplasty scar to maintain the aesthetic outcome. A large mass, arising from the abdominal wall and extending intra-abdominally, was excised and was determined to be a recurrent desmoid tumor. CONCLUSIONS Recurrent anterior abdominal wall desmoid tumors in post-menopausal women are rare and locally aggressive, with a high risk of recurrence. During abdominal wall repair in abdominoplasty, desmoid tumor filaments might seed deep intra-abdominally. Therefore, it is necessary to take adequate safe margins before abdominal wall repair. Post-operatively, surgeons should keep a high index of suspicion for tumor recurrence.

Primary apocrine carcinoma of the axilla in a male patient: a case report.

Primary apocrine sweat gland carcinoma is a rare neoplasm. It is usually slow growing and is often suspected to be a benign disease at initial assessment. A thorough clinical and histological workup is required for diagnosis. Treatment of choice is wide local excision with clear margins.