Real options valuation of US federal renewable energy research,development, demonstration,and deployment

Benefits analysis of US Federal government research, development, demonstration, and deployment (RD³) programmes for renewable energy (RE) technology improvement typically employs a deterministic forecast of the cost and performance of renewable and non-renewable fuels. The benefits estimate for the programme derives from the difference between two forecasts, with and without the RD³ programme in place. Three deficiencies of this approach are that it ignores: (1) uncertainty in the cost of non-renewable energy (NRE); (2) the possibility of adjustment to the RD³ effort commensurate with the evolving state of the world; and (3) the underlying technical risk associated with RD³. In this paper, an intuitive approach to determining the option value of RE RD³ is developed. This approach seeks to tackle the first two deficiencies noted above by providing an estimate via a compound real option of an RE RD³ programme in a future with uncertain NRE costs. A binomial lattice reveals the economic intuition underlying the decision-making process, while a numerical example illustrates the option components embedded in a simplified representation of current US Federal RE RD³.     

Catalytic decomposition of biomass tars with iron oxide catalysts

Catalytic gasification of wood (Cedar) biomass was carried out using a specially designed flow-type double beds micro reactor in a two step process: temperature programmed non-catalytic steam gasification of biomass was performed in the first (top) bed at 200–850 °C followed by catalytic decomposition gasification of volatile matters (including tars) in the second (bottom) bed at a constant temperature, mainly 600 °C. Iron oxide catalysts, which transformed to Fe₃O₄ after use possessed catalytic activity in biomass tar decomposition. Above 90% of the volatile matters was gasified by the use of iron oxide catalyst (prepared from FeCl₃ and NH_3aq) at SV of 4.5 × 10³ h^?1. Tar was decomposed over the iron oxide catalysts followed by water gas shift reaction. Surface area of the iron oxide seemed to be an important factor for the catalytic tar decomposition. The activity of the iron oxide catalysts for tar decomposition seemed stable with cyclic use but the activity of the catalysts for the water gas shift reaction decreased with repeated use.     

Studies on the overall safety aspects during irradiation of TeO2 in the central thimble of the TRIGA research reactor

The purpose of this study is to provide a detailed safety analysis of overall system and components in terms of their ability to provide optimum output from the irradiation of TeO₂ in the central thimble of the 3 MW TRIGA MARK II research reactor at Atomic Energy Research Establishment (AERE), Savar, Dhaka, Bangladesh. It identifies safety issues relevant to ¹³¹I radioisotope production and ensures that safety analysis and design are consistent. It evaluates threats developed within the facility during the irradiation process and ultimately ensures establishment of in-core safety limits and conditions at all stages of ¹³¹I production. In-core irradiation safety not only ensures the safe operation of the reactor but also strengthens the production of radioisotopes (RI). This study attempts to review and modify all safety related events and aspects relating to RI production. The three-dimensional continuous energy Monte Carlo code MCNP is used to develop a versatile and accurate full-core model of the TRIGA core. The cross-section library and fission product inventory are generated by using NJOY and ORIGEN computer codes. The methodology to evaluate heat generation and other relevant parameters necessary to provide enough information for thermal hydraulic analysis are discussed. The neutron flux distribution inside the dry and water filled central thimble is determined in order to locate the highest neutron flux trapping position. The thermal hydraulic and safety analysis are performed by elaborate numerical analysis as well as by using GENGTC computer code. A mock-up facility has also been developed to supplement and verify the theoretically predicted results. The total energy generated during irradiation of 50 gm TeO₂ sample in dry condition is found to be 113.84 w of which 75% energy is due to neutron heating and rest of the amount is from gamma heating. Around 11.28 w of heat energy is also generated in the quartz vial. When the total generated-heat transfer is considered through conduction and radiation mechanisms, the calculated temperature of 50 g of TeO₂ reaches at 970 °C. Considering simultaneous heat transfer mechanisms, (conduction, radiation and convection) the calculated maximum temperature of the 50 g of TeO₂ powder comes down at 680 °C. It may be pointed out that very high amount of heat is generated during the irradiation of TeO₂ at 3 MW reactor power in dry condition which is nearly the melting point of TeO₂ and may be termed as unsafe mode of irradiation.     

Glass fibers with clay nanocomposite coating: Improved barrier resistance in alkaline environment

Coatings made from neat vinyl ester and nanoclay reinforced vinyl ester composites are applied onto individual glass fibers as well as rovings to evaluate their barrier resistance against alkali and moisture attack. The fibers coated with clay nanocomposites present a significantly less damage caused by the diffusing alkali ions, giving rise to a much higher residual tensile strength after aging than the fibers without coating or those with a neat polymer coating. The static fatigue test performed on individual fibers verifies the advantage of using nanoclay composite to retard the corrosion process under the combined stress and alkaline environment. Similar beneficial effects of incorporating nanoclay on residual strength are identified for impregnated fiber bundles. The above observations confirm the excellent barrier characteristics of intercalated/exfoliated nanoclay in polymer that are applied in composite structures on both the microscopic and macroscopic scales.     

NMR Fingerprinting of Chemical Changes in Asphalt Fractions on Oxidation

Abstract

The composition of asphalt has been the subject of much study because such data are required in determining its performance-related properties. A problem inherent in studying asphalt composition is its chemical complexity; however, the characterization of asphalt can be better achieved by separating into fractions. In this work, the chemical property of commercial-grade asphalt obtained from BAPCO refinery, Bahrain (BH), was carried out. The rolling thin-film oven (RTFO), used for short-term aging, and pressurized aging vessel (PAV), used for long-term aging, ASTM D4124 (1991) method was used to separate fresh and aged asphalt into four generic fractions such as asphaltenes, polar aromatics, naphthene aromatics, and saturates. The Corbett fractionation procedure was used to separate fresh and aged asphalt into four generic fractions such as asphaltenes, polar aromatics, naphthene aromatics, and saturates. Nuclear magnetic resonance (NMR) was employed to fingerprint the chemical changes that occurred in asphalt during the aging processes. NMR measurements of asphalt fractions showed that during aging, isomerization and dehydrogenation types of reactions took place. Significant differences were observed between the structure and composition of fresh and aged fractions of asphalt. Results from NMR spectrometry provided significant information concerning the chemical transformations that occurred during the aging processes.     

The presence of substituents on the aryl moiety of the aryl phosphoramidate derivative of d4T enhances anti-HIV efficacy in cell culture: A structure-activity relationship

Since thiols can undergo nitrosation and the cell membrane is rich in thiol-containing proteins, we considered the possibility that membrane surface thiols may regulate cellular entry of NO. Recently, protein disulfide isomerase (PDI), a protein that catalyzes thio-disulfide exchange reactions, has been found on the cell-surface membrane. We hypothesized that cell-surface PDI reacts with NO, catalyzes S-nitrosation reactions, and facilitates NO transfer from the extracellular to intracellular compartment. We observed that PDI catalyzes the S-nitrosothiol-dependent oxidation of the heme group of myoglobin (15-fold increase in the rate of oxidation compared with control), and that NO reduces the activity of PDI by 73.1 +/- 21.8% (P < 0.005). To assess the role of PDI in the cellular action of NO, we inhibited human erythroleukemia (HEL) cell-surface PDI expression using an antisense phosphorothioate oligodeoxynucleotide directed against PDI mRNA. This oligodeoxynucleotide decreased cell-surface PDI content by 74.1 +/- 9.3% and PDI folding activity by 46.6 +/- 3.5% compared with untreated or "scrambled" phosphorothioate oligodeoxynucleotide-treated cells (P < 0.0001). This decrease in cell-surface PDI was associated with a significant decrease in cyclic guanosine monophosphate (cGMP) generation after S-nitrosothiol exposure (65.4 +/- 26.7% reduction compared with control; P < 0.05), with no effect on cyclic adenosine monophosphate (cAMP) generation after prostaglandin E1 exposure. These data demonstrate that the cellular entry of NO involves a transnitrosation mechanism catalyzed by cell-surface PDI. These observations suggest a unique mechanism by which extracellular NO gains access to the intracellular environment.     

High rates of discitis following surgery for prolapsed intervertebral discs at a hospital in Pakistan

OBJECTIVES: To confirm the presence of an outbreak of postoperative infections following laminectomy and to determine the infection rate after interventions were instituted. DESIGN: Retrospective cohort study. Medical records were reviewed, personnel interviewed, and premises examined. SETTING: Surgical unit of hospital A in Pakistan. SUBJECTS: Patients who had surgical laminectomy between January 1993 and July 1994. INTERVENTION: Instructive program for nursing and medical staff in December 1993. RESULTS: From January to December 1993, 6 (15%) of 41 laminectomy patients developed postoperative discitis. The risk of discitis varied significantly by surgeon (P = .016); patients who had one particular surgeon, surgeon A, were nine times more likely to develop postoperative infections than patients who did not have surgeon A. Patients were not consistently cleaned or shaved before coming to the operating room, and personnel moved back and forth between the operation theater and other parts of the hospital without changing their gowns or slippers. After the instructional intervention, between January and July 1994, 2 (6%) of 31 laminectomy patients developed postoperative discitis, a rate not significantly lower than in the preceding 12 months (P = .45). Overall, from January 1993 through July 1994, female patients were more likely to develop discitis than males (31% vs 7%; relative risk, 4.4; 95% confidence interval, 1.3-15.6; P < .032). CONCLUSION: Endemic conditions require that laminectomy at hospital A be limited to those situations where the benefits of the surgery exceed the considerable risk of postoperative discitis.     

Pharmacokinetics and metabolic disposition of 14C-metronidazole-derived radioactivity in rat after intravenous and intravaginal administration

Urinary metabolites and the pharmacokinetics of radioactivity derived from 14C-metronidazole (14C-MTZ) were determined after intravenous (iv) or intravaginal (ivg) administration of 10 mg/kg to adult rats. Following iv or ivg administration, the disappearance of 14C from blood followed the kinetics of a two-compartment open-system model. The blood half-lives of 14C during the beta-phase were 10.9 +/- 1.6 and 13.6 +/- 4.2 hr, after iv and ivg administration, respectively. After ivg application, the MTZ-derived radioactivity was detected in tail blood at 5 min, peaked at 1 hr, declined rapidly to 6 hr and more slowly thereafter. The vaginal absorption half-life of 14C-MTZ was 0.28 +/- 0.09 hr. About 12% of the administered dose remained in the vagina after 1 hr and 1.5% after 24 hr. At 24 hr, the tissue distribution and concentration of 14C were similar in iv and ivg dosed rats, the highest 14C concentration being present in the kidneys and lowest in the fat. The percentages of the dose excreted in 24 hr in the urine and feces were 58 and 15 after iv administration, compared to 37 and 40 after the ivg route, respectively. Unchanged 14C-MTZ and five of its metabolites were detected in the urine irrespective of the route of administration. The results show that metronidazole is rapidly absorbed through the vaginal mucosa of the rat and the metabolism and excretion of this chemotherapeutic agent are influenced by the route of administration.     

Combined crease recovery finishing and pigment printing

The combined application of crease recovery finishing (using a dimethyloldihydroxyethylene urea-based finish) and pigment printing is evaluated in this study. The use of a small amount of ammonium chloride in a combined print–finish process induces significant pigment print paste viscosity losses. However, the catalyst 2-aminoethanesulphonic acid produces negligible viscosity reduction when used in the combined print–finish process, coupled with the desired levels of finish and pigment print performance. Similar dry crease recovery, breaking load, colour strength and colour fastness properties are achieved by using 2-aminoethanesulphonic acid in the combined print–finish process relative to the conventional print–finish process.