The effects of saponin,antimony and glue on zinc electrowinning from Kidd Creek electrolyte

The effects of Saponin alone and in combination with antimony and glue on zinc deposition current efficiency and polarization and on the morphology and orientation of 6h and 24h zinc deposits electrowon at 500 A m^–2 and 38°C from Kidd Creek zinc electrolyte were determined. Saponin, at concentrations to 100mgl^–1, was weakly polarizing, changed the preferred deposit orientation from basal to intermediate and decreased the current efficiency. At optimum glue + antimony levels, Saponin concentrations 5mgl^–1 resulted in an increase in zinc deposition current efficiency and consistently gave either a <114><112><103><102><101> or a <101><112> preferred deposit orientation depending on the antimony + glue combination used. Tests run for 24h for selected combinations of Saponin, antimony and glue confirmed the results obtained for the 6h studies.     

How do biologists respond to low-intensity armed conflicts? The case of Bangladesh (1961–2011)

Armed conflict affects the biological diversity and biological research regime of a country. This paper takes a low-intensity armed conflict in the biologically and ethnically diverse Chittagong Hill Tracts (CHT) of Bangladesh, as an example, and assesses the response of biologists to this conflict. The study spans the last 50 years dividing it into three periods: pre-conflict (1961?1974), conflict (1975–1997) and post-conflict (1998–2011). Interactions with selected researchers and a literature survey showed that sporadic, intermittent biological research was conducted in this region even during the conflict. The number of research initiatives substantially increased and became more diverse over the last decade. Research opportunity has increased mainly because of improved security and accessibility. Nevertheless, despite the research capacity and a positive attitude among the researchers, some fundamental issues still limit long-term research in this area. The continuing volatile situation due to slow implementation of the 1997 Peace Accord and the tension between rebel factions and indigenous and settler communities in some areas continue to be serious concerns for studying and conserving the biodiversity of this region. Innovative research approaches and the full implementation of the peace agreement are vital to improving the situation for biological research in the CHT. The paper underlines the importance of a biologist’s self-motivation to respond to low-intensity armed conflicts.     

Plant Cell Walls as Dietary Fibre: Range,Structure, Processing and Function

The ingestion of dietary fibre has been correlated with the prevention of many health-threatening diseases and cancers. Plant cell walls are the major source of dietary fibre and this review investigates the relationship between the structure of different types of plant cell walls and their beneficial effects. The effects of processing and cooking on dietary fibre are also examined. Structure–function relationships between individual cell wall components and the beneficial effects of dietary fibre are not well defined and it may be that the physical, physiochemical and topochemical properties of plant cell walls and their components are also important.     

Solvent Extraction of Fatty Acids from Amylose Inclusion Complexes

The extractability of palmitic and other common fatty acids from inclusion complexes with potato amylose was studied using a wide range of common lipid solvents. At ambient temperature negligible yields were obtained with light petroleum or diethyl ether, and yields were low with most other solvents except those containing methanol or water. At 100°C, methanol, ethanol and propanol and all alcohol-water mixtures gave good yields. Complexes of amylose with 1-O-palmitoyllysophosphatidylcholine also gave good yields when extracted with propanol-water (3:1) at 100°C. Since more rigorous conditions are required for extraction of lipids from native cereal starch granules, it seems that the barrier to lipid extraction is the structure of the granule rather than the resistance to lipid extraction of any possible inclusion complexes in the granules.     

Extraction of Lipids from Cereal Starches with Hot Aqueous Alcohols

Cereal starches were extracted at 100°C with various proportions of lower alcohols and water to establish optimum conditions. Lipid yields generally exceeding 90% were obtained with one two-hour extraction of maize starch at 100°C when using not less than 14 ml of 75–85% methanol, 10 ml of 75% ethanol, 12 ml of 74–78% n-propanol, 14 ml of 74–78% isopropanol, or 17 ml of 84% n-butanol per gram of starch. Similar results were obtained with wheat A-starch ( > 8 μm granule diameter), wheat B-starch ( < 8 μm granule diameter) and rice starch using n-propanol-water, and with rice starch using methanol-water. Yields decreased if the proportions of alcohol and water were not kept within well-defined limits, especially with butanol and ethanol. The preferred conditions for complete recovery of lipids were two 2-hour extractions and one 1-hour extraction at 100°C with not less than 16 ml of 75% n-propanol per gram of starch.     

Changes in myocardial hemodynamics and contractile function in patients under surgical treatment for prostatic adenoma

Hemodynamics and left ventricular myocardial contractility in 170 patients who underwent surgery of prostatic adenoma were examined in preoperative period and 16 days after single-stage transvesical adenomectomy. The age of the patients varied from 52 to 85 years. Echocardiography and the dilution method were used for the evaluation. The increase of end-diastolic and end-systolic volumes, stroke volume, cardiac index, was registered. The combined pharmacological treatment made it possible to decrease the number of operative and postoperative cardiovascular complications.     

"Adaptive" behavior of ligand-gated ion channels: constraints by thermodynamics

The calcium-induced calcium release channel of the cardiac sarcoplasmic reticulum has been reported to inactivate in a novel manner (termed "adaptation"), which permits reactivation by exposure to successively higher concentrations of calcium. I examined the limitations placed by thermodynamics on the possible kinetic mechanisms for such behavior. The mechanism suggested by Gyorke and Fill, in which the affinity of a calcium-binding site decreases during adaptation, is not thermodynamically feasible for a passive system, but requires an external input of free energy. Possible sources of such energy are 1) metabolic energy, which is excluded by the fact that adaptation was observed in isolated channels in the absence of ATP, or 2) coupling of ion permeation to gating, for which there is currently no evidence. I derived a general limit on the thermodynamic feasibility of a sequence of channel activations and adaptations, irrespective of channel kinetics, from the requirement that the free energy must decrease during the spontaneous evolution of the system from the state existing immediately after a step increase in [Ca2+] to the state of maximum open probability that follows. The opening of the channel must involve an increase in free energy, which must be compensated by the free energy released by the incremental binding of calcium. This requirement leads to a complicated system of inequalities, which was simplified and manipulated algebraically into the form of a linear programming problem. Numerical solution of this problem showed that the sequence of adaptations of the SR channel observed by Gyorke and Fill requires the presence of at least 10 calcium-binding sites on the channel if it is to occur in the absence of exogenous sources of free energy. This indicates either that a large number of calcium-binding sites participate in the regulation of the SR calcium release channel, or that the existing data are significantly flawed with respect to the low open probability in the resting state, the importance of "calcium spike" artifacts from flash photolysis, or both.     

The effect of nonablative laser energy on the ultrastructure of joint capsular collagen

This study was designed to evaluate the effect of laser energy at nonablative levels on the ultrastructure of joint capsular collagen. The femoropatellar joint capsules of six mature New Zealand white rabbits were harvested immediately after death. Specimens were divided into three treatment groups (5, 10, and 15 watts) and one control group. Laser energy was applied using a holmium: YAG laser. Transmission electron microscopy showed significant ultrastructural alterations in collagenous architecture for all laser treatment groups, with increased fibril cross-sectional diameter for each of the treated groups. The fibrils began to lose their distinct edges and their periodical cross-striations at subsequently higher energy densities. A morphometric analysis showed that each subsequently higher laser energy caused a significant increase in collagen fibril diameter. Ultrastructural alteration of collagen fibril architecture caused by the thermal effect of laser energy is probably the dominant mechanism of laser-induced tissue shrinkage.     

Defining the positive tilt test: a study of healthy adults with moderate acute blood loss

STUDY OBJECTIVES: To define a set of orthostatic vital signs that minimize the frequency of false-positives among healthy individuals while maximizing sensitivity in detecting acute moderate blood loss and to determine the sensitivity and specificity of this optimized tilt test in detecting acute moderate blood loss. DESIGN AND INTERVENTION: Postural vital signs were recorded in a standardized manner before and after 450-mL phlebotomy. Paired comparisons were done for a variety of criteria for a positive tilt test using receiver-operating characteristic curves. SETTING AND TYPE OF PARTICIPANTS: Three hundred forty-five healthy euvolemic adult volunteer blood donors were tested at three community blood donation centers over a one-year period. Subjects were prospectively divided into group 1 (less than age 65; 301) and group 2 (age 65 or older; 44). MEASUREMENTS AND MAIN RESULTS: For each combination of pulse and blood pressure in group 1, a change in pulse alone had the same or higher sensitivity with at least the same specificity. Pulse alone was similarly superior in group 2 compared with previously published combinations of pulse and blood pressure. Even the optimized tilt test had limited sensitivity in detecting acute moderate blood loss with high specificity. CONCLUSION: In applying the tilt test to young adults without cardiovascular disease, pulse measurement usually is all that is necessary.