Integration of biology, ecology and engineering for sustainable algal‑based biofuel and bioproduct biorefinery

Despite years of concerted research efforts, an industrial-scale technology has yet to emerge for production and conversion of algal biomass into biofuels and bioproducts. The objective of this review is to explore the ways of possible integration of biology, ecology and engineering for sustainable large algal cultivation and biofuel production systems. Beside the costs of nutrients, such as nitrogen and phosphorous, and fresh water, upstream technologies which are not ready for commercialization both impede economic feasibility and conflict with the ecological benefits in the sector. Focusing mainly on the engineering side of chemical conversion of algae to biodiesel has also become obstacle. However, to reduce the costs, one potential strategy has been progressing steadily to synergistically link algal aquaculture to the governmentally mandated reduction of nitrogen and phosphorous concentrations in municipal wastewater. Recent research also supports the suppositions of scalability and cost reduction. Noticeably, less is known of the economic impact of conversion of the whole algae-based biorefinery sector with additional biochemical and thermochemical processes and integration with ecological constraints. This review finds that a biorefinery approach with integrated biology, ecology, and engineering could lead to a feasible algal-based technology for variety of biofuels and bioproducts

High-Speed High Effiency Large Area Resonant Cavity Enhanced p-I-n Photodiodes for Multimode Fiber Communications

Cataloged from PDF version of article.In this letter, we report AlGaAs–GaAs p-i-n photodiodes with a 3-dB bandwidth in excess of 10 GHz for devices as large as 60- m diameter. Resonant cavity enhanced photodetection is employed to improve quantum efficiency, resulting in more than 90% peak quantum efficiency at 850 nm

High bandwidth-efficiency resonant cavity enhanced Schottky photodiodes for 800-850 nm wavelength operation

Cataloged from PDF version of article.High-speed resonant cavity enhanced Schottky photodiodes operating in 800-850 nm wavelength region are demonstrated. The devices are fabricated in the AlGaAs/GaAs material system. The Schottky contact is a semitransparent Au film which also serves as the top reflector of the Fabry-Perot cavity. The detectors exhibit a peak quantum efficiency of eta = 0.5 at lambda = 827 nm wavelength and a 3 dB bandwidth of more than 50 GHz resulting in a bandwidth-efficiency product of more than 25 GHz. (C) 1998 American Institute of Physic

High-speed >90% quantum-efficiency p–i–n photodiodes with a resonance wavelength adjustable in the 795–835 nm range

Cataloged from PDF version of article.We report GaAs/AlGaAs-based high-speed, high-efficiency, resonant cavity enhanced p–i–nphotodiodes. The devices were fabricated by using a microwave-compatible fabrication process. By using a postprocess recess etch, we tuned the resonance wavelength from 835 to 795 nm while keeping the peak efficiencies above 90%. The maximum quantum efficiency was 92% at a resonance wavelength of 823 nm. The photodiode had an experimental setup-limited temporal response of 12 ps. When the system response is deconvolved, the 3 dB bandwidth corresponds to 50 GHz, which is in good agreement with our theoretical calculations. © 1999 American Institute of Physic

Robust Entanglement in Atomic Systems via Lambda-Type Processes

It is shown that the system of two three-level atoms in $\Lambda$ configuration in a cavity can evolve to a long-lived maximum entangled state if the Stokes photons vanish from the cavity by means of either leakage or damping. The difference in evolution picture corresponding to the general model and effective model with two-photon process in two-level system is discussed.Comment: 10 pages, 3 figure

Long-term prevalence of post-traumatic stress disorder symptoms in patients after secondary peritonitis

INTRODUCTION: The aim of this study was to determine the long-term prevalence of post-traumatic stress disorder (PTSD) symptomology in patients following secondary peritonitis and to determine whether the prevalence of PTSD-related symptoms differed between patients admitted to the intensive care unit (ICU) and patients admitted only to the surgical ward. METHOD: A retrospective cohort of consecutive patients treated for secondary peritonitis was sent a postal survey containing a self-report questionnaire, namely the Post-traumatic Stress Syndrome 10-question inventory (PTSS-10). From a database of 278 patients undergoing surgery for secondary peritonitis between 1994 and 2000, 131 patients were long-term survivors (follow-up period at least four years) and were eligible for inclusion in our study, conducted at a tertiary referral hospital in Amsterdam, The Netherlands. RESULTS: The response rate was 86%, yielding a cohort of 100 patients; 61% of these patients had been admitted to the ICU. PTSD-related symptoms were found in 24% (95% confidence interval 17% to 33%) of patients when a PTSS-10 score of 35 was chosen as the cutoff, whereas the prevalence of PTSD symptomology when borderline patients scoring 27 points or more were included was 38% (95% confidence interval 29% to 48%). In a multivariate analyses controlling for age, sex, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, number of relaparotomies and length of hospital stay, the likelihood of ICU-admitted patients having PTSD symptomology was 4.3 times higher (95% confidence interval 1.11 to 16.5) than patients not admitted to the ICU, using a PTSS-10 score cutoff of 35 or greater. Older patients and males were less likely to report PTSD symptoms. CONCLUSION: Nearly a quarter of patients receiving surgical treatment for secondary peritonitis developed PTSD symptoms. Patients admitted to the ICU were at significantly greater risk for having PTSD symptoms after adjusting for baseline differences, in particular ag