Bio-methanol: How energy choices in the western United States can help mitigate global climate change

Converting available biomass from municipal, agricultural and forest wastes to bio-methanol can result in significant environmental and economic benefits. Keeping these benefits in mind, one plausible scenario discussed here is the potential to produce energy using bio-methanol in five states of the western United States. In this scenario, the bio-methanol produced is from different biomass sources and used as a substitute for fossil fuels in energy production. In the U.S. West, forest materials are the dominant biomass waste source in Idaho, Montana, Oregon and Washington, while in California, the greatest amount of available biomass is from municipal wastes. Using a 100% rate of substitution, bio-methanol produced from these sources can replace an amount equivalent to most or all of the gasoline consumed by motor vehicles in each state. In contrast, when bio-methanol powered fuel cells are used to produce electricity, it is possible to generate 12–25% of the total electricity consumed annually in these five states.As a gasoline substitute, bio-methanol can optimally reduce vehicle C emissions by 2–29 Tg of C (23–81% of the total emitted by each state). Alternatively, if bio-methanol supported fuel cells are used to generate electricity, from 2 to 32 Tg of C emissions can be avoided. The emissions avoided, in this case, could equate to 25–32% of the total emissions produced by these particular western states when fossil fuels are used to generate electricity. The actual C emissions avoided will be lower than the estimates here because C emissions from the methanol production processes are not included; however, such emissions are expected to be relatively low. In general, there is less carbon emitted when bio-methanol is used to generate electricity with fuel cells than when it is used as a motor vehicle fuel.In the state of Washington, thinning “high-fire-risk” small stems, namely 5.1–22.9 cm diameter trees, from wildfire-prone forests and using them to produce methanol for electricity generation with fuel cells would avoid C emissions of 3.7–7.3 Mg C/ha. Alternatively, when wood-methanol produced from the high-fire-risk wood is used as a gasoline substitute, 3.3–6.6 Mg C/ha of carbon emissions are avoided. If these same “high-fire-risk” woody stems were burned during a wildfire 7.9 Mg C/ha would be emitted in the state of Washington alone. Although detailed economic analyses of producing methanol from biomass are in its infancy, we believe that converting biomass into methanol and substituting it for fossil-fuel-based energy production is a viable option in locations that have high biomass availability.     

Analysis and characterization of the hyperchaos generated by a semiconductor laser subject to a delayed feedback loop

We characterize the chaotic dynamics of semiconductor lasers subject to either optical or electrooptical feedback modeled by Lang-Kobayashi and Ikeda equations, respectively. This characterization is relevant for secure optical communications based on chaos encryption. In particular, for each system we compute as a function of tunable parameters the Lyapunov spectrum, Kaplan-Yorke dimension and Kolmogorov-Sinai entropy.     

Thiocompounds as simulants of sulphur mustard for testing of protective barriers

The protective potential of protective devices such as respirators, suits, gloves, and overboots is widely evaluated using the standard colorimetric test (spot disc breakthrough time test, also called SD BTT) involving sulfur mustard (SM) as the challenge chemical. The vesicant nature of SM makes the test inconvenient and poses stringent safety demands. Moreover, such tests are allowed only at a limited number of facilities, causing delay in product development and supply. This prompted the present study on the search for suitable SM simulant responsive to SD BTT test. The diffusivities at BTT (D_BTT) of 10 commercially available thiocompounds through butyl rubber (IIR) were compared vis‐a‐vis D_BTT of SM. For three representative thiocompounds, namely methyl (phenyl thio)acetate, 2‐chloroethyl phenyl sulfide (2‐CEPS) and phenyl‐n‐propyl sulfide (PNPS), the transport parameters through IIR were obtained. PNPS and 2‐CEPS were further compared with respect to D_BTT in elastomers such as IIR, ethylene–propylene–diene methylene rubber, polydimethylsiloxane, nitrile rubber, polybutadiene, and natural rubber. 2‐CEPS showed generally same order of D_BTT as SM implying its potential use as a simulant. The transport parameters for various 2‐CEPS/elastomer systems were also determined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Evaluation of the efficacy of naltrexone in alcoholism by the determination of serum carbohydrate-deficient transferrin

Naltrexone (NTX) has been shown to be a useful drug for the treatment of alcohol dependence (AD). Carbohydrate-deficient transferrin (CDT) in serum is a new biologic marker of alcohol abuse. To evaluate the efficacy of NTX (50 mg/d) in AD, a group of 20 alcoholics with CDT > 20 U/l was studied using monthly laboratory tests (CDT, ESR, AST, ALT, GGT) and specific psychological testing (CAGE). After the second month statistically significant differences in CDT levels were found. By the end of the study, 13 patients (responders) had normalized their CDT levels. There was no correlation between CDT values and the other laboratory markers. The difference in routine laboratory markers between responders and non responders was not significant. NTX was well tolerated by all the patients and significant alcohol abstinence was achieved. CDT was demonstrated to be a effective marker for the evaluation of alcoholic abstinence during treatment with NTX. Superior results were obtained in comparison with the routine customary markers for AD.     

Theory of main resonances in directly modulated diode lasers

Domains of existence of the main resonances in directly modulated semiconductor lasers are obtained by application of quasi-conservation theory. The predictions are compared with numerical results coming from a direct integration of the model equations and with experimental observations reported by other groups. In both cases we find a qualitative good agreement. We consider a model that contains explicitly the gain saturation and spontaneous emission terms. We find that the spontaneous emission strongly modifies the qualitative behavior of the instabilities boundaries, while the gain saturation leads to a simple quantitative shift of boundaries. We also find that modulation of the pump or loss produce equivalent results if the respective modulation amplitudes are conveniently rescaled     

Authors' Reply

The authors accept the corrections, pointed out by E.G. Bakhoum, to their original paper (see ibid., vol.48, no.4, p.632-41, Nov. 2005) an apologise for their mistakes