Effects of nonionic surfactants on bacterial transport through porous media

Nonionic surfactants of the form CxEy, where x is the number of carbons in the alkyl chain and y is the number of ethylene oxide units in the polyoxyethylene (POE) chain, were studied for their ability to alter the transport of Sphingomonas pacilimobilis through an aquifer sand. The surfactants C12E4 (Brij 30) and C12E23 (Brij 35) were the focus of this study. Through a systematic study, it was shown that these nonionic surfactants were able to enhance the transport of this bacterial culture through porous media. The magnitude of the enhancement increased with decreasing solution ionic strength and increasing POE chain length. The mechanism of this enhanced transport appears to be due to expansion of the electric double layer about the bacteria and aquifer sand through displacement of the counterions by the sorbed surfactant. This expanded electric double layer increases the electrostatic repulsion, with a resultant reduction in the collision efficiency and an increase in the Langmuirian blocking parameter. Application of the colloid filtration theory with the experimental parameters of this study shows that nonionic surfactants have the potential to significantly enhance the bacterial travel distance, especially for low ionic strength systems.     

Percutaneous endovascular stent-graft repair of iliac artery aneurysms

There has been a tremendous explosion in the area of DNA vaccine research over the last 4 years, particularly in relation to antiviral vaccines. This report discusses the development and application of this new technology with regard to parasitic infections. Progress has been made towards the development of a vaccine against malaria, cryptosporidiosis, leishmaniasis, toxoplasmosis and schistosomiasis. In the future, nucleic acid vaccines will be a useful tool to help control these and other parasitic infections.     

A model for collaboration in quality improvement projects: implementing a weight-based heparin dosing nomogram across an integrated health care delivery system

BACKGROUND: At Aurora Health Care, an integrated delivery system based in Milwaukee, a system-level clinical quality improvement department was established in 1995 to facilitate collaboration on clinical quality improvement (QI) initiatives. THE COLLABORATIVE MODEL: A model was developed to use expertise within the system and avoid unnecessary duplication of efforts, while maintaining buy-in for the project's interventions at the point of service delivery. It was believed that a single team could design the improvement efforts or guidelines, and then work at a more local level with a different group of people to implement the processes. APPLYING THE MODEL TO THE HEPARIN QI PROJECT: Anticoagulation with heparin is considered the mainstay of treatment for pulmonary embolism and deep venous thrombosis. However, a large gap was found between present anticoagulation practices and published best practice in regards to achieving a key process measure. To reduce the overall time to achieving effective anticoagulation, a system-level team created an intervention primarily consisting of a preprinted order sheet, including the weight-based heparin dosing nomogram, and an education plan for physicians and other health care professionals. Significant improvement was observed at all pilot sites with overall rates of adequate anticoagulation within the first 24 hours improving from 73% to 95%. DISCUSSION: The system was able to standardize care at four of its five major hospitals and provide for better patient outcomes to a larger segment of the community, and then to replicate the heparin project to four additional sites during a six-month period. This model has been successfully applied to other quality improvement projects.     

Requirements of nutrients which participate in erythropoiesis

Proteins, some minerals and vitamins, play important roles in erythropoiesis and the survival of the red blood cell. This article deals specifically with the physiological requirements and recommended intakes of iron, folate and vitamin B12. A comparison of the physiologic iron requirements according to age and sex, and the amount of iron which is actually absorbed from the diets consumed by the lower socioeconomic strata of the Venezuelan population; indicates that these diets do not satisfy the requirements at all ages. Such disparity is most marked in children below three years of age, in adolescents and in women during their reproductive age. Failure to do so leads to varying degrees of iron deficiency. This low bioavailability of the Venezuelan diet is also observed in other Latin American diets consumed by the same low socioeconomic strata, which explains the high prevalence of iron-deficiency anemia in the vulnerable groups. The low intake of fruits and vegetables by the lower socioeconomic strata of the Latin American population prevents these sectors from consuming an adequate intake of folate, failing to fulfill the daily recommended intake (3.3 - 3.6 micrograms/kg body weight). This situation is aggravated in pregnant and lactating women who require an additional intake of 300 micrograms and 100 micrograms, respectively. Prevalence of folate deficiency in the first stage may be in the order of 30% in some regions. In the second stage of deficiency, characterized by megaloblastic changes in the bone marrow and an erythrocyte folate concentration of less than 50 micrograms/lt, it could be as high as 40% in pregnant women. Nutritional vitamin B12 deficiency does not constitute a health problem in Latin America. Various surveys in the lower socioeconomic strata have reported normal or higher than normal serum B12 concentrations, compared to well-nourished populations.     

Nutrition yesterday and today

The history of human nutrition from primitive times to actuality is briefly outlined. Many of the modern nutritional problems can be traced back to changes caused by the introduction of agriculture and, more recently, food technology. These developments have changed the composition of the diet to which the primitive hunter-gatherers had adapted themselves during millions of years. Changes in food habits and the beginning of the science of nutrition are discussed, and a brief review of nutritional recommendations is provided. The terms of nutritional goals and rules, so much used today, are of recent introduction. Nevertheless, norms, normal allowances and other similar expressions have since long ago been in use. Nutritional goals should be based on the vital habits of the population for which they are intended, and should be adapted to the ever emerging new findings in nutritional sciences.     

Effects of porous media preparation on bacteria transport through laboratory columns.

Bacterial and colloid transport experiments related to environmental systems are typically performed in the laboratory, with sand often used as the porous media. In order to prepare the sand, mechanical sieving is frequently used to tighten the sand grain size distribution. However, mechanical sieving has been reported to provide insufficient repeatability between identical colloidal transport experiments. This work examined the deficiencies of mechanical sieving with respect to bacterial transport through sand columns. It was found that sieving with standard brass sieves (1) contaminates the sand with copper and zinc as a linear function of sieving time and (2) inefficiently sizes sand grains below 300 microm (the largest size examined in this study) due to rapid clogging of the sieves. A procedure was developed that allows utilization of brass sieves for sizing the sand grains and removes the metal contamination introduced from the sieves. Bacterial transport experiments utilizing this column preparation procedure gave repeatable breakthrough curves. Further examination of the effects of these treatments on bacterial transport showed interesting results. First, it was found that the metal contamination did not affect the clean-bed bacterial transport. Second. it was found that variations of the column flushing procedure did not alter the clean-bed breakthrough of the bacteria, but did alter the inter-particle blocking. Finally, it was found that the shape of the sand grains (oblong vs. rounded) significantly alters the bacterial transport. with the transport being dominated by the smallest dimension of the oblong grains.     

Hematologic profile and absorption of iron from diets consumed by a population of low socioeconomic level of 2 Venezuelan states

Hematologic studies carried out in inhabitants of the State of Carabobo revealed that 19% of the subjects studied presented iron deficiency, this being more prominent in women and in children. Iron deficiency anemia was absent in men, while in the other groups its frequency, as registered, was from 5 to 13%. Tests for iron absorption from foods which form the average diet of the population in the Carabobo State, and the diet consumed by adults from the low socioeconomic strata in the States of Carabobo and Yaracuy, demonstrated that in normal subjects, bioavailability is lower than physiological requirements of men, women and children. In the iron-deficient subjects, its bioavailability can cover physiological needs. It is estimated that an important proportion of the population strata consuming such diets, suffer from iron nutritional deficiency, especially women during the reproductive age, and children.     

Molecular characterization of dissolved organic matter in freshwater wetlands of the Florida Everglades

In this study, the molecular composition of dissolved organic matter (DOM), collected from wetlands of the Southern Everglades, was examined using a variety of analytical techniques in order to characterize its sources and transformation in the environment. The methods applied for the characterization of DOM included fluorescence spectroscopy, solid state 13C CPMAS NMR spectroscopy, and pyrolysis-GC/MS. The relative abundance of protein-like components and carbohydrates increased from the canal site to more remote freshwater marsh sites suggesting that significant amounts of non-humic DOM are autochthonously produced within the freshwater marshes, and are not exclusively introduced through canal inputs. Such in situ DOM production is important when considering how DOM from canals is processed and transported to downstream estuaries of Florida Bay.     

Evaluation of the effect of aerobic–anaerobic conditions on photohydrogen and chlorophyll a production by environmental Egyptian cyanobacterial and green algal species

In this study, we tested four algal species (Synechocystis sp. PCC 6803 and three novel algal species isolated from Egyptian paddy rice soil, having high 16S rRNA gene sequence identity to Nostoc spongiaeforme, Parachlorella kessleri SAG 211-11 and Nostoc sp. PCC 7524) under aerobic, anaerobic and 3% CO₂-supplemented anaerobic condition. Significant changes in photohydrogen production, morphology, chlorophyll a and protein content/pattern were observed in all species, when grown in these different conditions. H₂ production was higher in anaerobic condition in all species with the highest H₂ production rate of 4 mmol H₂ mg Chla^?1 h^?1 at 24 h in Synechocystis sp. In contrast, Chla content and protein content decreased (%) in N. spongiaeforme, (29%, 58%), P. kessleri (47%, 7%) and Nostoc sp. (59%, 65%).The anaerobic condition with 3% CO₂ stimulated early production of H₂ in all species except Synechocystis sp. Our results compared all selected algal species under different growth conditions for the screening of a superior H₂-producing algal species that can help to address engineering challenges in the field of large-scale H₂ photoproduction by microalgae.     

On the energetic cost of sociality

Measurements of oxygen consumption from ant colonies of various sizes of Odontomachus bauri, Camponotus rufipes and Zacryptocerus depressus showed a complex and nonlinear relationship between colony size and energy consumption per unit mass. Results show that at certain critical colony sizes, the colonies energy consumption is larger than the sum of the average energy requirement of the individually workers, and near maximal colony sizes, the energy consumption of the colony per unit mass tends exponentially to that of the average individual worker. We propose that social complexity is related to energy consumption in a discontinuous manner and is bound by both, negentropy content of a society and social optimization mechanisms.