Experimental study of a multiple-effect humidification solar desalination technique

The object of this research is to experimentally investigate the principal operating parameters of a new desalination process working with an air multiple-effect humidification-dehumidification method. A test set-up was designed and constructed to carry out and optimize this technique. The main parts of the present set-up consist of a heat equipment device (heat exchanger), a spray humidifier and a dehumidifier system. This equipment was used to simulate the seawater desalination process experimentally with an eight-stage air solar collector heating-humidifying system. The outlet temperature of the air solar collector was correlated for use in the desalination process as a solar heating device. The operating conditions studied were: ratio of water to dry air mass flow rate through the system, humidifier inlet absolute humidity, dry air mass flow rate through the system and solar irradiation or humidifier inlet air temperature. The experimental results obtained were used to put stress and correlate the influence of the different operating conditions on the behavior of the eight-stage air heating-humidifying desalination process. The ratio of water to dry air mass flow rates was optimized, precisely 45%. The value of dry air mass flow rate through the system can be also varied with solar radiation in order to have a maximum of humidity content at the end of the system and though working in an adiabatic humidification process.     

Genetic and antigenic analysis of human rotavirus prevalent in Al-Taif, Saudi Arabia

The subgroup, serotype and electropherotype diversity of human rotavirus strains was investigated in Al-Taif, Saudi Arabia. Out of 349 faecal samples collected from diarrhoeic children, 150 (43 percent) tested rotavirus positive by a group-A specific enzyme-linked immunosorbent assay (ELISA). The majority (87 percent) of the infected children were below 2 years of age. Subgrouping and serotyping of rotaviruses with specific monoclonal antibodies showed that of the 150 rotavirus positive specimens, 17 percent belonged to subgroup I, 59 per cent belonged to subgroup II, and 24 percent were neither subgroup I nor subgroup II. The specimens were typed, as serotype 1 (43 percent), serotype 2 (5 percent), serotype 3 (11 percent), serotype 4 (10 percent) or mixed serotypes (3 percent). The remaining 41 (27 percent) specimens were untypeable. None of the serotypes showed association with a particular age group. An electrophoretic analysis of viral RNA revealed 11 distinct patterns (six long and five short). The majority, 78 percent were long patterns and 22 percent were short patterns. Analysis of the specimens for which subgroups, serotypes and electropherotypes were available indicated that a given RNA pattern does not correspond to a particular subgroup or serotype.     

The effects of age on onset and recovery from atracurium, rocuronium and vecuronium blockade

Elderly patients may show an age-related decline in physiologic functions, which may be responsible for the prolonged duration of some neuromuscular blocking agents. Previous studies have yielded conflicting results as to the effects of these drugs in the elderly. METHODS: After obtaining informed consent and approval of the Ethics Committee, we compared onset and recovery times of single IV doses of atracurium, rocuronium, and vecuronium given to 108 patients divided into three groups according to age (18-50, 51-64, > or = 65 years). Following oxazepam premedication and fentanyl and thiopentone induction, patients were randomly allocated to receive atracurium, rocuronium or vecuronium (0.5, 0.6, or 0.1 mg/kg, respectively) in < or = 0.8 vol.% enflurane (end-tidal)-nitrous oxide anaesthesia. Muscular relaxation was assessed by electromyographic (EMG) recording of the adductor pollicis muscle after supramaximal single-twitch stimulation of the ulnar nerve every 10 s. Onset time and recovery to 25%, 75% and 90% of twitch control values (DUR25, 75, 90) were recorded. Creatinine clearance predicted from serum creatinine (Ccr) was correlated with recovery from neuromuscular block. RESULTS: Onset time was not different among groups or relaxants. The results showed a prolonged duration of action for atracurium (DUR75, DUR90), rocuronium (DUR25, DUR75), and vecuronium (DUR25) in the elderly. A number of patients did not reach DUR75 or DUR90. There was a significant relationship between age and failure to return to control values during recovery from neuromuscular block, especially after atracurium and rocuronium. Ccr showed a negative correlation with age for all relaxants, but a negative significant correlation between Ccr and recovery was found only for rocuronium. CONCLUSIONS: This study suggests that onset time for atracurium, rocuronium and vecuronium is not age-dependent. Recovery was prolonged in the elderly for all three relaxants. This effect appears to be secondary to changes in body composition and function accompanying the aging process. Neither atracurium nor vecuronium depends significantly on the kidney for elimination, but the negative correlation between Ccr and rocuronium suggests an appreciable role for the kidney in the elimination of this relaxant. The long recovery times observed in this study could also be related to enflurane anaesthesia. We suggest that failure of EMG responses to return to baseline values during recovery from neuromuscular block may be related to age, especially for atracurium and rocuronium.     

IgG2 associated hypergammaglobulinaemia in some Nigerians with HIV infection

Concentrations of immunoglobulins (IgA, IgG and IgM) were measured in Nigerians with (HIV) infection. Considerable elevations up to two-fold the reference values were observed for IgG and IgM in the patient group as a whole but elevations in IgA concentration were least marked albeit significantly different from the healthy subjects. Elevation of a particular isotype was not always concomitant with elevation of the other major classes in the same patient. Overall, these elevations were observed in both symptomatic and asymptomatic infected subjects. Further analysis of IgG hyperglobulinemia showed that increases in this major class may be due to increased IgG2 subclass concentrations. It is suggested that elevation of IgG2 subclass in Nigerians with HIV infection and not IgG1 or IgG3 may be due to genetic and environmental factors rather than variation in the strain of the virus.     

Batch kinetics and modelling of ethanolic fermentation of whey

The fermentation of whey by Kluyveromyces marxianus strain MTCC 1288 was studied using varying lactose concentrations at constant temperature and pH. The increase in substrate concentration up to a certain limit was accompanied by an increase in ethanol formation, for example, at a substrate concentration of 10 g L^?1, the production of ethanol was 0.618 g L^?1 whereas at 50 g L^?1 it was 3.98 g L^?1. However, an increase in lactose concentration to 100 g L^?1 led to a drastic decrease in product formation and substrate utilization. The maximum ethanol yield was obtained with an initial lactose concentration of 50 g L^?1. A method of batch kinetics was utilized to formulate a mathematical model using substrate and product inhibition constants. The model successfully simulated the batch kinetics observed at S₀ = 10 and 50 g L^?1 but failed in case of S₀ = 100 g L^?1 because of strong substrate inhibition.     

Electrical Conductivity of RuO2–Borosilicate Glasses: Effect of the Synthesis Route

Although glass–RuO₂ composites are well known for their particular electrical properties, the reasons for their very low percolation thresholds are still subject to debate. In this paper, a detailed study of the influence of various experimental parameters (temperature, RuO₂ content, stirring, etc.) on the electrical conductivity and, in particular, on the percolation threshold in borosilicate glass–RuO₂ composites is presented. This percolation threshold is shown to increase by a factor of two (from 0.6 to 1.2 vol%) when stirring is applied during synthesis and by more than a factor of three (>2.1 vol%) when a sol–gel route is used. Besides, the study of various synthesis temperatures reveals that the electronic part of the electrical conductivity is highly correlated to Ru solubility in the glass matrix. It can be concluded from these various experiments that both the presence of dissolved ruthenium in the glass matrix and the possibility of RuO₂ particles to rearrange in the melt in order to form kind of a network are necessary for a low percolation threshold.     

Job Behavior of Construction Project Managers: Determinants and Assessment

The paper reports the findings of an investigation into the psychosocial aspects of the work of construction project managers (PMs) in the United Kingdom. A theoretical model, which identified the different variables that may influence the behavior and effectiveness of PMs was developed. This study has used an adapted form of the behaviorally anchored rating scales (BARS) to measure a PM's effectiveness. The technique yielded five behavioral dimensions by which a PM's role may be described, and it was used in a survey involving 62 PMs. Analysis of the data suggests that a PM's effectiveness was influenced by situational and personal variables. The results strongly suggest that by understanding the complexity of such relationships, construction firms can influence the direction and behavior of PMs. The results also suggest that the behavior of PMs and project performance varied independently.     

Power system design and in orbit performance of Algeria's first micro satellite Alsat-1

On the 28th November 2002, Algeria's first enhanced micro satellite was launched into a 686 km low earth orbit onboard a Cosmos 3M rocket from Plesetsk. The spacecraft was designed, manufactured and launched as a technology transfer programme between the National Centre of Space Techniques (CNTS) Algeria and Surrey Satellite Technology Limited (SSTL) United Kingdom in the timescale of 18 months.     

Histochemical analysis of bandage contact lens precipitates.

Contact lens deposits have been reported previously with extended wear of soft contact lenses, with proteins, lipids, mucous, and various salts such as chloride, potassium and calcium being deposited on the lens surface [1]. We report an unusual case of precipitates on the surface of a bandage contact lens (BCL) following intensive treatment with topical preservative free artificial tears. Evaluation included microscopic and histochemical analysis of the BCL. We have also reviewed the literature for previous reports of contact lens precipitates.