Syngas fermentation to biofuel: Evaluation of carbon monoxide mass transfer coefficient (kLa) in different reactor configurations

Lignocellulosic biomass such as agri‐residues, agri‐processing by‐products, and energy crops do not compete with food and feed, and is considered to be the ideal renewable feedstocks for biofuel production. Gasification of biomass produces synthesis gas (syngas), a mixture primarily consisting of CO and H₂. The produced syngas can be converted to ethanol by anaerobic microbial catalysts especially acetogenic bacteria such as various clostridia species.One of the major drawbacks associated with syngas fermentation is the mass transfer limitation of these sparingly soluble gases in the aqueous phase. One way of addressing this issue is the improvement in reactor design to achieve a higher volumetric mass transfer coefficient (k_La). In this study, different reactor configurations such as a column diffuser, a 20‐μm bulb diffuser, gas sparger, gas sparger with mechanical mixing, air‐lift reactor combined with a 20‐μm bulb diffuser, air‐lift reactor combined with a single gas entry point, and a submerged composite hollow fiber membrane (CHFM) module were employed to examine the k_La values. The k_La values reported in this study ranged from 0.4 to 91.08 h^?1. The highest k_La of 91.08 h^?1 was obtained in the air‐lift reactor combined with a 20‐μm bulb diffuser, whereas the reactor with the CHFM showed the lowest k_La of 0.4 h^?1. By considering both the k_La value and the statistical significance of each configuration, the air‐lift reactor combined with a 20‐μm bulb diffuser was found to be the ideal reactor configuration for carbon monoxide mass transfer in an aqueous phase. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2011     

Probucol treatment reverses antioxidant and functional deficit in diabetic cardiomyopathy

Earlier we reported that probucol treatment subsequent to the induction of diabetes can prevent diabetes-associated changes in myocardial antioxidants as well as function at 8 weeks. In this study, we examined the efficacy of probucol in the reversal of diabetes induced myocardial changes. Rats were made diabetic with a single injection of streptozotocin (65 mg/kg, i.v.). After 4 weeks of induction of diabetes, a group of animals was treated on alternate days with probucol (10 mg/kg i.p.), a known lipid lowering agent with antioxidant properties. At 8 weeks, there was a significant drop in the left ventricle (LVSP) and aortic systolic pressures (ASP) in the diabetic group. Hearts from these animals showed an increase in the thiobarbituric acid reacting substances (TBARS), indicating increased lipid peroxidation. This was accompanied by a decrease in the myocardial antioxidant enzymes activities, superoxide dismutase (SOD) and glutathione peroxidase (GSHPx). Myocardial catalase activity in the diabetic group was higher. In the diabetic + probucol group both LVSP and ASP showed significant recovery. This was also accompanied by an improvement in SOD and GSHPx activities and there was further increase in the catalase activity. Levels of the TBARS were decreased in this group. These data provide evidence that diabetic cardiomyopathy is associated with an antioxidant deficit which can be reversed with probucol treatment. Improved cardiac function with probucol may be due to the recovery of antioxidants in the heart.     

Dairy propionibacteria as direct-fed microbials: in vitro effect on acid metabolism of <Emphasis Type="Italic">Streptococcus bovis</Emphasis> and <Emphasis Type="Italic">Megasphaera elsdenii</Emphasis>

Ruminal acidosis caused by accumulation of lactic acid, a decrease of pH in the rumen and subsequent imbalance of the rumen fermentation process, affects the health and productivity of dairy cows and beef cattle. Direct-fed microbials have potential for use in the control and prevention of ruminal acidosis. This study investigated the interaction between five strains of dairy propionibacteria, Megasphaera elsdenii and Streptococcus bovis in various co-culture combinations in a simulated rumen environment comprising unmodified rumen digesta supplemented with excess glucose. While suppression of lactic acid accumulation by both the dairy propionibacteria and M. elsdenii in the presence of S. bovis in the simulated rumen conditions was evident, propionibacteria were found to be more effective than M. elsdenii in controlling lactic acid levels.     

Differences in Breast Cancer Survival between Public and Private Care in New Zealand: Which Factors Contribute?

BackgroundPatients who received private health care appear to have better survival from breast cancer compared to those who received public care. This study investigated if this applied to New Zealand women and identified factors that could explain such disparities.MethodsThis study involved all women who were diagnosed with primary breast cancer in two health regions in New Zealand, covering about 40% of the national population, between June 2000 and May 2013. Patients who received public care for primary treatment, mostly surgical treatment, were compared with those who received private care in terms of demographics, mode of presentation, disease factors, comorbidity index and treatment factors. Cox regression modelling was performed with stepwise adjustments, and hazards of breast cancer specific mortality associated with the type of health care received was assessed.ResultsOf the 14,468 patients, 8,916 (61.6%) received public care. Compared to patients treated in private care facilities, they were older, more likely to be Māori, Pacifika or Asian and to reside in deprived neighbourhoods and rural areas, and less likely to be diagnosed with early staged cancer and to receive timely cancer treatments. They had a higher risk of mortality from breast cancer (hazard ratio: 1.95; 95% CI: 1.75, 2.17), of which 80% (95% CI: 63%, 100%) was explained by baseline differences, particularly related to ethnicity, stage at diagnosis and type of loco-regional therapy. After controlling for these demographic, disease and treatment factors, the risk of mortality was still 14% higher in the public sector patients.ConclusionsEthnicity, stage at diagnosis and type of loco-regional therapy were the three key contributors to survival disparities between patients treated in public and private health care facilities in New Zealand. The findings underscore the need for more efforts to improve the quality, timeliness and equitability of public cancer care services.     

A study of air particulate pollution in colombo using a nuclear-related analytical technique

Air particulate matter of two size fractions (coarse [2.5–10 Μm] and fine [less than 2.5 Μm]) were collected at an urban residential site (Colombo University ground) over a period of 12 mo during 1996 using a Gent PM10 stacked filter unit. Seventy-five sets of samples collected during this period were analyzed for 10 elements: Al, Si, K, S, Ca, Ti, Fe, Zn, Br, and Pb by energy-dispersive X-ray fluorescence, which is a multielement analysis. This is a highly sensitive technique enabling quantitative analysis of very low masses. The average concentrations of lead, sulfur, and bromine, which are generally associated with combustion products of automotive exhausts, dominate the fine fraction in this study. The minimum and maximum concentration of lead resulting in an annual average of 0.09 Μg/m³ was found to be 0.0042 and 0.441 Μg/m³ in particulate matter with less than 10 Μm equivalent aerodynamic diameter. The maximum concentration determined is well below the limits set by the World Health Organization (0.5–1.0 Μg/m³). The recommended value for Pb in Sri Lanka is 0.5 Μg/m³. Al, Si, Ca, Ti, and Fe exhibited enhanced concentrations in the coarse fraction, which probably originate from disturbed soil as a result of wind and traffic.     

Nearest-neighbor thermodynamics and NMR of DNA sequences with internal A.A, C.C, G.G, and T.T mismatches

Thermodynamic measurements are reported for 51 DNA duplexes with A.A, C.C, G.G, and T.T single mismatches in all possible Watson-Crick contexts. These measurements were used to test the applicability of the nearest-neighbor model and to calculate the 16 unique nearest-neighbor parameters for the 4 single like with like base mismatches next to a Watson-Crick pair. The observed trend in stabilities of mismatches at 37 degrees C is G.G > T.T approximately A.A > C.C. The observed stability trend for the closing Watson-Crick pair on the 5' side of the mismatch is G.C >/= C.G >/= A.T >/= T.A. The mismatch contribution to duplex stability ranges from -2.22 kcal/mol for GGC.GGC to +2.66 kcal/mol for ACT.ACT. The mismatch nearest-neighbor parameters predict the measured thermodynamics with average deviations of DeltaG degrees 37 = 3.3%, DeltaH degrees = 7. 4%, DeltaS degrees = 8.1%, and TM = 1.1 degrees C. The imino proton region of 1-D NMR spectra shows that G.G and T.T mismatches form hydrogen-bonded structures that vary depending on the Watson-Crick context. The data reported here combined with our previous work provide for the first time a complete set of thermodynamic parameters for molecular recognition of DNA by DNA with or without single internal mismatches. The results are useful for primer design and understanding the mechanism of triplet repeat diseases.