Catalytic hydrocracking of jatropha oil over natural clay for bio-jet fuel production.

Currently, the conversion of biomass to produce high-valued biofuels such as biodiesel and bio-jet fuel has attached booming interests, when used for partial replacement of petroleum fuels in different ratios is a promising solution due to the problem of depleting petroleum reserves and environmental purposes. Non-edible Jatropha oil can be transformed to biofuel when subjected to were hydrocracking at hydrogen pressure using an activated natural clay as a catalyst in a high pressure batch reactor. The type of product and its quality and quantity depend on the process conditions such as reaction time, temperature, and catalyst type, form, and amount. The present work aims to study the hydrocracking process of Jatropha oil at different operating conditions. The catalyst is characterized using SEM, FTIR, XRF, and XRD. The effect of process conditions variation have been studied and discussed. The results showed the highest yield of 40% bio-jet fuel was achieved at a temperature of 350 °C, H2 pressure of 4 bar, and reaction time of 18 min. the bio-jet fuel products were tested and their specifications were conformed to ASTM D1655 specifications, viz the freezing point (-56 °C), the flash point (53 °C), and existent gum content (5.9 mg/100 ml).

Cerebral palsy in Riyadh, Saudi Arabia: II. Associations between gestational age, birthweight and cerebral palsy.

One hundred and ninety infants with cerebral palsy were studied in Riyadh , Saudi Arabia. Bleeding during pregnancy and toxemic complications seemed to be important causative factors, particularly in preterm and small-for-date infants. Infants born after breech presentation, assisted labour and failed obstetric procedures totalled 20.0% of all cases. Poor feeding, stiffness and infection were the main clinical presentations. Spasticity was the predominant neurological abnormality irrespective of birth weight, with spastic diplegia (31.0%) and quadriplegia (26.3%) contributing greatly to the overall pattern. Speech defects and, to a lesser extent, epilepsy were the most frequent associated handicaps. The majority of children with cerebral palsy (65.8%) were severely handicapped. Saudi Arabia is making rapid economic, social and medical progress, but currently facilities to meet the needs of cerebral palsy victims and their families are inadequate. Based on the above study it is recommended that: (1) paramedical services at community level be initiated; (2) more rehabilitative and educational programs be established; (3) better and more modern obstetric care be provided; (4) close co-operation among the medical professionals be facilitated since cerebral palsy cases can be managed best through a team approach.

Cerebral palsy in Riyadh, Saudi Arabia: I. Aetiological factors.

Aetiological factors predisposing to cerebral palsy were investigated in 190 children with this condition seen in Riyadh , Saudi Arabia since January 1980. Ninety-four (49.5%) of the cases were natal in origin, 63 (33.1%) prenatal and 33 (17.4%) postnatal. Anoxia was the most common aetiological factor, accounting for 38 cases (20%), followed by prematurity in 18 (9.5%). These two factors combined accounted for 29.5% of all cases and 59.5% of those in the natal group. Idiopathic cases, the third largest group, accounted for 9.0%. Certain factors were shown to predispose to specific neurological deficits, the majority of the 190 patients being spastic diplegic (31%) or quadriplegic (26.3%). Saudi Arabia is going through a process of massive economic, social and medical progress. In view of improvements in all these areas and of other factors, a change in the pattern of incidence of cerebral palsy in Saudi Arabia is expected in the future.

Active transport membrane concentration amplifiers.

Three different active transport membrane configurations are suggested for achieving concentration amplification in a circulating substrate solution. The steady-state characteristics of the structures are investigated on the basis of a linear approximation of the rate of active transport. An analysis of the effects of system parameters and geometry on the concentration gradient along the flow path is presented. It is seen that the concentration gradient may be synthesized by appropriate choice of membrane arrangement, flow and physico-chemical transport parameters.

A study of 214 neonates with infection in the maternity and Children's Hospital of Riyadh, Saudi Arabia.

This is a prospective study of 214 neonates admitted with suspected infection to the Maternity and Children's Hospital in Riyadh over the 15 months period, February 1980 to May 1981. Many of the infants showed clinical evidence of severe infection and 48 (22.4%) died, the highest mortality being among the low birth weight group, preterms and light-for-dates (33.3%). The infants tended to be from a low socio-economic class and bottle or mixed fed. The majority of their mothers were illiterate and many sought medical advice at a late stage. Recommendations are put forward to ensure that this vulnerable group receives a better standard of health education.