Risk Assessment and Safety Evaluation Using Probabilistic Fault Tree Analysis

Risk assessment is an essential prelude to the development of accident prevention strategies in any chemical or petrochemical industry. Many techniques and methodologies such as HAZOP, failure mode effect analysis, fault tree analysis, preliminary hazard analysis, quantitative risk assessment and probabilistic safety analysis are available to conduct qualitative, quantitative, and probabilistic risk assessment. However, these methodologies are limited by: extensive data requirements, the length of study, results are not directly interpretable for decision making, simulation is often difficult, and they are applicable only at the operation or late design stage. Khan et al. (2001a) recently proposed a detailed methodology for risk assessment and safety evaluation. This methodology is simple, yet it is effective in safety and design-related decision making, and it has been applied successfully to many case studies. It is named SCAP, where S stands for safety, C and A stand for credible accident respectively, and P stands for probabilistic fault tree analysis. This paper recapitulates the SCAP methodology and demonstrates its application to a petrochemical plant.     

Occurrence of cestodes and comparative efficacy of Typha angustata and sulphadimidine against cestodes in Columba livia domestica (Domestic Pigeon)

The occurrence of intestinal parasites of Columba livia domestica has been on the increase, leading to high economic and production losses with more fatal cases. This study was designed to investigate the prevalence of cestodes in pigeons and determine the efficacy of Typha angustata extract and sulphadimidine against these cestodes in the domestic pigeon. A total of 30 pigeons were examined. 18 (60%) pigeons were found infected with only one type of cestode species (Raillietina spp.). The difference in prevalence between males and females was statistically significant (χ² = 8.167, p = 0.004). The mean EPG count in group A (treated with T. angustata extract) before treatment and after treatment was 176 ± 4.33 and 155 ± 4.24, respectively. In group B (treated with sulphadimidine), the mean EPG calculated before treatment and after treatment was 184 ± 6.74 and 35 ± 3.53, respectively. The efficacy at day 28 of T. angustata and Sulphadimidine was 11.93% and 80.97%, respectively. It was concluded on the basis of the EPG and efficacy data that T. angustata extract had low efficacy against raillietiniasis, while as sulphadimidine, which is also used before to treat different intestinal parasites, had a good efficacy against raillietiniasis. Further studies are required to know the prevalence of other gastrointestinal parasites in pigeons and efficacy of different medicinal plants against such parasites.     

Removal of cadmium(II) ion from aqueous system by dry biomass, immobilized live and heat-inactivated Oscillatoria sp. H1 isolated from freshwater (Mogan Lake)

Oscillatoria sp. H1 (Cyanobacteria, microalgae) isolated from Mogan Lake was used for the removal of cadmium ions from aqueous solutions as its dry biomass, alive and heat-inactivated immobilized form on Ca-alginate. Particularly, the effect of physicochemical parameters like pH, initial concentration and contact time were investigated. The sorption of Cd(II) ions on the sorbent used was examined for the cadmium concentrations within the range of 25-250 mg/L. The biosorption of Cd(II) increased as the initial concentration of Cd(II) ions increased in the medium up to 100 mg/L. Maximum biosorption capacities for plain alginate beads, dry biomass, immobilized live Oscillatoria sp. H1 and immobilized heat-inactivated Oscillatoria sp. H1 were 21.2, 30.1, 32.2 and 27.5 mg/g, respectively. Biosorption equilibrium was established in about 1 h for the biosorption processes. The biosorption was well described by Langmuir and Freundlich adsorption isotherms. Maximum adsorption was observed at pH 6.0. The alginate-algae beads could be regenerated using 50 mL of 0.1 mol/L HCl solution with about 85% recovery.     

Allelopathic Interactions in Agroforestry Systems

Agroforestry is a modern tool to develop sustainable land use and to increase food production by growing woody species (trees, shrubs, palms, bamboos, etc.) with agricultural crops and/or animals in some form of spatial arrangement or temporal sequence. Because these species co-exist with the agricultural crops, their allelopathic compatibility may be crucial to determine the success of an agroforestry system. A survey of the available information reveals that most of the agroforestry species (AF species) have negative allelopathic effects on food and fodder crops. Therefore, it is desirable to do further research in this direction so that AF species with no or positive allelopathic effects on the companion crops may be promoted for agroforestry programs. As AF species remain a part of the agroecosystem for a longer period, and most of them produce a large amount of leaves and litter, their allelochemicals may play an important role in developing an eco-friendly pest management strategy. Besides these generally studied aspects of allelopathy, some comparatively newer aspects of research have been identified, such as evaluation of qualitative yield of agroforestry systems, selective behavior of the allelochemicals, effect on soil quality, and the role of tree allelochemicals in animal and human nutrition. If given due consideration, allelopathy could play a pivotal role in conservation of the highly threatened environment, biodiversity, natural resource base, and making agriculture more sustainable through broadening the scope of agroforestry.     

Compact reduced thioredoxin structure from the thermophilic bacteria Thermus thermophilus

The X-ray crystallographic structure of a thioredoxin from Thermus thermophilus was solved to 1.8 A resolution by molecular replacement. The crystals' space group was C2 with cell dimensions of a = 40.91, b = 95.44, c = 56.68 A, beta =91.41 degrees, with two molecules in the asymmetric unit. Unlike the reported thioredoxin structures, the biological unit of T. thermophilus thioredoxin is a dimer both in solution and in the crystal. The fold conforms to the "thioredoxin fold" that is common over a class of nine protein families including thioredoxin; however, the folded portion of this protein is much more compact than other thioredoxins previously solved by X-ray crystallography being reduced by one alpha-helix and one beta-strand. As with other thioredoxins, the active site is highly conserved even though the variation in sequence can be quite large. The T. thermophilus thioredoxin has some variability at the active site, especially compared with previously solved structures from bacterial sources.     

Genetic mapping of Dn7, a rye gene conferring resistance to the Russian wheat aphid in wheat

The Russian wheat aphid is a significant pest problem in wheat and barley in North America. Genetic resistance in wheat is the most effective and economical means to control the damage caused by the aphid. Dn7 is a rye gene located on chromosome 1RS that confers resistance to the Russian wheat aphid. The gene was previously transferred from rye into a wheat background via a 1RS/1BL translocation. This study was conducted to genetically map Dn7 and to characterize the type of resistance the gene confers. The resistant line '94M370' was crossed with a susceptible wheat cultivar that also contains a pair of 1RS/1BL translocation chromosomes. The F₂ progeny from this cross segregated for resistance in a ratio of 3 resistant: 1 susceptible, indicating a single dominant gene. One-hundred and eleven RFLP markers previously mapped on wheat chromosomes 1A, 1B and 1D, barley chromosome 1H and rye chromosome 1R, were used to screen the parents for polymorphism. A genetic map containing six markers linked to Dn7, encompassing 28.2 cM, was constructed. The markers flanking Dn7 were Xbcd1434 and XksuD14, which mapped 1.4 cM and 7.4 cM from Dn7, respectively. Dn7 confers antixenosis, and provides a higher level of resistance than that provided by Dn4. The applications of Dn7 and the linked markers in wheat breeding are discussed.Communicated by J. Dvorak     

Aryl tetrahydropyridine inhibitors of farnesyltransferase: glycine,phenylalanine and histidine derivatives

Inhibitors of farnesyltransferase are effective against a variety of tumors in mouse models of cancer. Clinical trials to evaluate these agents in humans are ongoing. In our effort to develop new farnesyltransferase inhibitors, we have discovered a series of aryl tetrahydropyridines that incorporate substituted glycine, phenylalanine and histidine residues. The design, synthesis, SAR and biological properties of these compounds will be discussed.     

Potential role of glycosidase inhibitors in industrial biotechnological applications

The nutrient content of food and animal feed may be improved through new knowledge about enzymatic changes in complex carbohydrates. Enzymatic hydrolysis of complex carbohydrates containing alpha or beta glycosidic bonds is very important in nutrition and in several technological processes. These enzymes are called glycosidases (Enzyme Class 3.2.1) and include amylases, pectinases and xylanases. They are present in many foods such as cereals, but their microbial analogues are often produced and added in many food processes, for instance to improve the shelf-life of bakery products, clear beer, produce glucose, fructose or dextrins, hydrolyse lactose, modify food pectins, or improve processes. However, many plant foods also contain endogenous inhibitors, which reduce the activity of glycosidases, in particular, proteins, peptides, complexing agents and phenolic compounds. The plant proteinaceous inhibitors of glycosidases are in focus in this review whose objective is to report the effect and implications of these inhibitors in industrial processes and applications. These studies will contribute to the optimisation of industrial processes by using modified enzymes not influenced by the natural inhibitors. They will also allow careful selection of raw material and reaction conditions, and future development of new genetic varieties low in inhibitors. These are all new and very promising concepts for the food and feed sector.     

Crystallographic structure and biochemical analysis of the Thermus thermophilus osmotically inducible protein C

The X-ray crystallographic structure of osmotically inducible Protein C from the thermophilic bacterium, Thermus thermophilus HB8, was solved to 1.6A using the multiple wavelength anomalous dispersion method and a selenomethionine incorporated protein (Se-MAD). The crystal space group was P1 with cell dimensions of a=37.58 A, b=40.95 A, c=48.14 A, alpha=76.9 degrees, beta=74.0 degrees and gamma=64.1 degrees. The two tightly interacting monomers in the asymmetric unit are related by a non-crystallographic 2-fold. The dimer structure is defined primarily by two very long anti-parallel, over-lapping alpha-helices at the core, with a further six-stranded anti-parallel beta-sheet on the outside of the structure. With respect to the beta-sheets, both A and B monomers contribute three strands each resulting in an intertwining of the structure. The active site consists of two cysteine residues from one monomer and an arginine and glutamic acid from the other. Enzymatic assays have revealed that T.thermophilus OsmC has a hydroperoxide peroxidase activity.     

Erectile dysfunction under age 40: etiology and role of contributing factors

The aim of this study was to evaluate the etiology of erectile dysfunction (ED) in patients under the age of 40 years. Eighty one patients were included in this study. All patients underwent a multidisciplinary diagnostic approach by color Doppler ultrasonography, dynamic pharmacocavernosometry (optional), selective pudendal pharmaco-arteriography (optional) and nocturnal penile tumescence monitoring by a Rigi-Scan (optional). Mean age of the population was 32 years. Psychogenic impotence was diagnosed in 50% of the patients and organic impotence was diagnosed in 45%. After the 3rd decade of life, a vasculogenic etiology was the most common cause of impotence. Smoking and hypertension played a major role as chronic contributing factors in the overall study population. Primary impotence was diagnosed in 11 patients who were unmarried. The rate of organic causes was 45% in this group (all vasculogenic in nature). Erectile dysfunction in younger patients and in patients with primary impotence is due mainly to organic causes, usually vascular in origin.