Numerical study of the thermal performance of a single-channel cooling PV system using baffles and different nanofluids.

The present numerical study reports the performance of a cooling system for solar photovoltaic panels (PV) using different nanofluids (Al2O3, CuO, and ZnO). A novel parallel flow channel with strategically placed baffles was analyzed to improve the heat transfer between the back of PV and the nanofluid. The nanoparticles' Brownian motion and the nanofluid temperature effect were considered. Computational fluid dynamics was used to simulate the interaction between the fluid in motion and panel materials. Various nanoparticle concentrations, Reynolds numbers (18-1800), and solar radiation values (200-1000 W/m2) were examined. The results showed that the nanofluid composed of CuO was the most effective, improving thermal efficiency by 5.67 % compared to pure water in the lowest Re range. A 10 % vol. concentration of Al2O3 reduced temperature by up to 15 % and increased electrical efficiency by 4 % when the Re varied from 18 to 42. However, increasing the Re number and having low solar radiation values decreased the contribution of the nanofluid. Additionally, using baffles in the flow channel improved electrical efficiency by 2 %.

[Osteochondritis dissecans of the acetabulum. Apropos of a case]. / L'ostéochondrite disséquante du cotyle. A propos d'un cas.

Osteochondritis dissecans acetabuli is a rare affection. The observation presented is one of a 23 year old man, who presented hip blockages in external flexion rotation. X-ray only allowed to find a sequestrum in the acetabulum by tomography-Arthroscanner confirmed the osteochondritis without cartilage rupture. Arthroscopy eliminated a cartilage lesion and directed towards a cavity filled by spongious bone through an extra articular approach.

Ecología y desarrollo

Los presentes trabajos fueron publicados en la Revista Pasos de San José de Costa Rica, tratan distintos aspectos de la temática ecológica

Ecología y desarrollo

Los presentes trabajos fueron publicados en la Revista Pasos de San José de Costa Rica, tratan distintos aspectos de la temática ecológica

Ecología y desarrollo

Los presentes trabajos fueron publicados en la Revists Pasos se San José de Costa Rica, tratan distintos aspectos de la temática ecológica

Recurrent posterior instability of the shoulder.

Seven cases of recurrent posterior instability of the shoulder were reviewed, three with recurrent subluxation and four with recurrent posterior dislocations. All were treated surgically, one by inverted Putti-Platt, one by glenoplasty and five by posterior bone block procedures. The follow-up goes from three to 17.5 years (mean 8.5 years). Clinical history and physical examination were the most accurate diagnostic methods. There were three excellent, one fair, and one poor results with two failures. The poor result and failure cases are due to technical errors, particularly because of wrong positioning of the graft in posterior bone block procedures. We suggest a bone graft with a projection of at least 15 mm beyond the glenoid rim to obtain a good result with this technique. Osteoarthritis does not seem to develop at long-term in our patients even with a poor result except for those with iatrogenic origin. The functional results are stable over time except for patients with osteoarthritis.

[Cubital dimelia. Apropos of a case with review of the literature]. / La dimélie cubitale. A propos d'un cas avec revue de la littérature.

Cubital or ulnar dimelia is a very rare congenital abnormality involving almost perfect duplication of the ulnar with absence of the radius, thumb and polydactyly. An eleven week old child was seen in the Department of Pediatric Surgery for a malformation of the left upper limb including deformity of the forearm with almost doubling of the hand and seven fingers. Radiological investigation revealed duplication of the ulna as well as of the metacarpals and fingers with absence of the radius and thumb. This type of abnormality remains controversial but clinical and radiological examination led to the conclusion of primary ulnar dimelia. We report a new case of this very rare congenital abnormality which was not accompanied by any other malformation.

[Arthroplastic resection of the shoulder. Results and indications apropos of 35 cases]. / La résection arthroplastique de l'épaule. Résultats et indications à propos de 35 cas.

The only aim of this retrospective study of 35 patients who had undergone resection of shoulder is to report overall results of this well established operation. Although no result could be rated as excellent, those in one half of the patients were evaluated as good and in one quarter as acceptable. The shoulder can be used in two-thirds of cases and of major importance is that pain is absent in two-thirds and tolerable in 80% of cases. In addition to cases of septic arthritis and poorly tolerated recurrent luxations, this operation is indicated for elderly patients with a fracture-luxation or compound fracture of upper end of humerus. However, the operation requires very strict conditions and re-attachment of the cap of rotator muscles. Resection of shoulder should therefore conserve a place in the therapeutic arsenal of shoulder disorders.