Hydrogen production by co-cultures of Clostridium butyricum and Rhodospeudomonas palustris: Optimization of yield using response surface methodology

Both dark and photo-fermentation can be used for biological hydrogen production; either performed separately, in two-stage systems, or in co-culture. A single stage process is less laborious and costly; however, the two types of microorganisms have different nutritional requirements requiring optimization of culture conditions. Here a response surface methodology (RSM) with a Box-Behnken design was used to optimize microorganism ratio and substrate and buffer concentrations, and to evaluate their interactive effects for maximization of hydrogen yield. Clostridium butyricum and Rhodopseudomonas palustris were grown on a potato starch/glucose base medium at 30 °C under continuous illumination (40 W m^?2 light intensity). The highest hydrogen yield, 6.4 ± 1.3 mol H₂/mol glucose, was obtained with a substrate concentration of 15 g/L, buffer concentration of 50 mM, and microorganism ratio of 3. The observed strong interaction between buffer and substrate concentration is most likely due to the need to optimize the pH for co-cultures.     

Detecting Cycle Failures at Signalized Intersections Using Video Image Processing

Abstract:   Signal cycle failure (or overflow) is an interrupted traffic condition in which a number of queued vehicles are unable to depart due to insufficient capacity during a signal cycle. Cycle failure detection is essential for identifying signal control problems at intersections. However, typical traffic sensors do not have the capability of capturing cycle failures. In this article, we introduce an algorithm for traffic signal cycle failure detection using video image processing. A cycle failure for a particular movement occurs when at least one vehicle must wait through more than one red light to complete the intended movement. The proposed cycle failure algorithm was implemented using Microsoft Visual C#. The system was tested with field data at different locations and time periods. The test results show that the algorithm works favorably: the system captured all the cycle failures and generated only three false alarms, which is approximately 0.9% of the total cycles tested.     

Fermentative hydrogen yields from different sugars by batch cultures of metabolically engineered Escherichia coli DJT135

Future sustainable production of biofuels will depend upon the ability to use complex substrates present in biomass if the use of simple sugars derived from food crops is to be avoided. Therefore, organisms capable of using a variety of fermentable carbon sources must be found or developed for processes that could produce hydrogen via fermentation. Here we have examined the ability of a metabolically engineered strain of Escherichia coli, DJT135, to produce hydrogen from glucose as well as various other carbon sources, including pentoses. The effects of pH, temperature and carbon source were investigated in batch experiments. Maximal hydrogen production from glucose was obtained at an initial pH of 6.5 and temperature of 35 °C. Kinetic growth studies showed that the μmax was 0.0495 h⁻¹ with a Ks of 0.0274 g L⁻¹ when glucose was the sole carbon source in M9 (1X) minimal medium. Among the many sugar and sugar derivatives tested, hydrogen yields were highest with fructose, sorbitol and d-glucose; 1.27, 1.46 and 1.51 mol H₂ mol⁻¹ substrate respectively.     

Learning agility: A construct whose time has come.

A significant consequence of today's dynamic, complex, and uncertain business environments is that leadership skills are subject to continual obsolescence and displacement. To be effective, leaders must demonstrate the flexibility and agility to adapt their behaviors as situations change. The willingness and capability to learn from experience and subsequently to apply that learning to perform successfully under new or first-time conditions becomes one of the most critical success factors for managers and executives. This article introduces and defines the concept of learning agility, reviews and discusses its theoretical and empirical background, and presents selected research findings related to the assessment of learning agility. Several areas for future research are also identified. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Single stage hydrogen production from cellulose through photo-fermentation by a co-culture of Cellulomonas fimi and Rhodopseudomonas palustris

Biohydrogen production from cellulose by a bacterial co-culture is a potentially promising approach for producing bioenergy from a low cost substrate. The use of a cellulolytic bacterium, Cellulomonas fimi, permits cellulose conversion and the in situ production of substrate for growth and hydrogen production by the photosynthetic bacterium Rhodopseudomonas palustris. Response surface methodology (RSM) with a Box-Behnken design (BBD) was used to examine variations in the key parameters: substrate (cellulose) concentration, yeast extract concentration and the microorganism ratio (Rps. palustris/C. fimi). For the co-culture of R. palustris and C. fimi the highest hydrogen production (44 mmol H₂/L) was achieved at the highest substrate concentration (5 g/L); however, the highest hydrogen yield (3.84 mol H₂/mol glucose equivalent) was observed at the lowest cellulose concentration and highest microorganism ratio. High COD removal efficiencies, over 70%, were achieved over a wide range of conditions and were positively affected by the concentration of yeast extract.     

"Empathy: A neglected topic in psychological research": Reply.

Replies to K. B. Clark's (see record 1980-09677-001) article on empathy by distinguishing empathy as a state or condition from the behaviors which stem from that state. Given the prerequisites of understanding and being able to identify emotional behavior, a person with empathy then shifts his or her point of view to comprehend the feeling state of another person. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Purification and characterization of pyruvate oxidoreductase from the photosynthetic bacterium Rhodobacter capsulatus

The effects of the addition of a calcium channel blocker, verapamil (20 mg/kg/day) to an ACE inhibitor, trandolapril (0.7 mg/kg/day) in a 6-month treatment on renal insufficiency development in rats with 5/6th nephrectomy, were studied. Every month we measured heart rate and arterial pressure by the tail-cuff method. Renal function studies were performed in metabolic cages. At the end of the study, renal tissue was prepared for light microscope analysis. Renal lesions were assessed by semiquantitative scores in a blind fashion. Corpuscular section area, intraglomerular and tubulointerstitial fibrosis were determined by digital image analysis with a specific software (Fibrosis HR) on syrium red-stained renal sections. Trandolapril markedly increased the survival ratio that after 6 months reached 87% in comparison with 61% in untreated rats. No mortality was observed in rats treated with the combination of verapamil and trandolapril. Trandolapril treatment prevented the development of hypertension. The combination verapamil-trandolapril did not induce further reduction on blood pressure. The untreated group showed a marked proteinuria, that in the trandolapril group showed an important reduction. The verapamil + trandolapril group showed a proteinuria significantly smaller than that of all the other groups. Light microscopy semiquantitative studies of the renal injury showed that the trandolapril and verapamil + trandolapril groups had a marked reduction in glomerular and tubulointerstitial alterations, compared with untreated animals. Quantitative determinations of glomerular and interstitial fibrosis performed on syrium red-stained renal sections demonstrated that fibrosis was reduced when rats when treated with trandolapril and even more with verapamil + trandolapril when they were compared to untreated animals' values. In conclusion, long-term treatment with verapamil given in addition to trandolapril produces additional protection against progressive renal injury associated to subtotal nephrectomy.