Liquid-liquid extraction and separation of total rare earth (RE) metals from polymetallic manganese nodule leaching solution

The study on the solvent extraction for quantitative and selective separation of total rare earth metals from the polymetallic nodule leach liquor was investigated. The typical leach liquor bearing 0. 094 g/L total rare earth, 0. 23 g/L Mn, 0.697 g/L Cu, 0.2 g/L Fe, 0.01 g/L Co and 0.735 g/L Ni was subjected to the removal iron content by precipitation method using Ca(OH)2 at pH 3.95, prior to solvent extraction of rare earth metals. Three different organo-phosphoric acid reagents(D2EHPA, PC88 A, Cyanex 272) were used to ascertain their performances and selectivity towards the loading of rare earth metals in presence of other base metals. Based on the results of eq. pH effect, the performances of above three extractants followed the order as: D2EHPA>PC88A>Cyanex 272. To ensure the absence of extraction of base metals(Cu, Co, Ni), the eq. pH of the solution was optimized at the level of 2.21, though higher rare earth metal extraction efficiency was observed at higher eq. pH with either of the extractants. The complete process flow diagram for substantial recovery of total rare earth was developed using D2 EHPA. Extraction isotherm plot was constructed at A:O=12:1, 3-stages and pHe=2.21, using 0.8 mol/L D2 EHPA and the predicted condition of this study was further confirmed by 6-Cycles Counter Current Simulation(CCS) study. The stripping of total rare earth from loaded organic phase(LO) was conducted using HCl solution. Mc-Cabe Thiele diagram study carried out at A:O=1:5 using 4 mol/L HCl showed that three theoretical stages were needed for quantitative stripping of total rare earth. The subsequent stripped solution resulted thus led to contain total rare earth of 5.6 g/L indicating a very high enrichment of total metals by solvent extraction(SX) process.     

Migrant Mothers: Richard Harrington’s Indigenous ‘Madonnas’

Canadian photographer Richard Harrington has been recognised since the 1950s for his photographs of the Arctic, and specifically for portraits of the Padleimiut taken at a hunting camp in 1950 during a winter of acute shortages. Three were selected for Edward Steichen’s The Family of Man (1955). Of that group, two focused on motherhood through depictions of childbirth and maternal love; the latter is sometimes referred to as ‘Canada’s Madonna and Child’, making a timeless secular icon from the representation of a crisis. Harrington was a documentary photographer who made his living as a freelance photojournalist specialising in human interest stories and travel features for magazines and newspapers. On assignment in British Columbia for the Hudson’s Bay Company magazine The Beaver, he photographed a First Nations mother and child, an image entitled ‘Madonna of the Peace’. This photograph later graced the cover of a Roman Catholic missionary magazine, Pôle et Tropiques. This article draws parallels between Harrington’s photographs of Indigenous mothers and children and Dorothea Lange’s Migrant Mother, using Harrington’s diaries and community-based research to reconstruct the lives of his subjects, and considering the sacrifice of knowledge to iconicity.     

Effect of hydrogen and neutron irradiation on the failure of flawed Zircaloy-2 pressure tubes

Experiments were made with Zircaloy-2 tubes containing axial slits. Failure stress at 20 and 300 °C is increased by neutron irradiation: hydride precipitates reduce failure stress at 20 °C but not at 300 °C. There is evidence that stress applied during irradiation, and neutron dose, affect failure stress.

Crack opening displacement measurements on notched bend specimens predicted within 20% the critical crack lengths measured on full size tubes.     

Identification of seven Treponema species in health- and disease-associated dental plaque by nested PCR

Species-specific nested PCR was used to detect Treponema amylovorum, Treponema denticola, Treponema maltophilum, Treponema medium, Treponema pectinovorum, Treponema socranskii, and Treponema vincentii in dental plaque. Subjects with periodontitis harbored all species, but T. pectinovorum and T. vincentii were not found in plaque from disease-free subjects.     

Ionic mechanisms of action of neurotensin in acutely dissociated neurons from the diagonal band of Broca of the rat

Whole cell recordings were performed on acutely dissociated neurons from the horizontal limb of the diagonal band of Broca (hDBB) from rats to elucidate the ionic mechanisms of action of neurotensin. Neurotensin caused a decrease in whole cell voltage-activated outward currents and failed to elicit a response when Ca2+ influx was blocked by changing the external solution to the one containing 0 mM Ca2+ and 50 microM Cd2+, suggesting the involvement of Ca2+-dependent conductances. Charybdotoxin, a specific blocker of voltage-sensitive calcium-activated K+ channels (IC), caused a decrease in outward currents comparable with that caused by blocking calcium influx and occluded the neurotensin-induced decrease in outward currents. Similarly, 50 microM tetraethylammonium ions also blocked the neurotensin response. Also neurotensin reduced whole cell barium currents (IBa) and calcium currents (ICa). Amiloride and omega-conotoxin GVIA, but not nimodipine, were able to eliminate the neurotensin-induced decrease in IBa. Thus T- and N- but not L-type calcium channels are subject to modulation by neurotensin, and this may account for its effects on IC. The predicted changes in action potential as a result of the blockade of currents through calcium channels culminating into changes in IC were confirmed in the bridge current-clamp recordings. Specifically, neurotensin application led to depolarization of the resting membrane potential, broadening of spike and a decrease in afterhyperpolarization and accommodation. These alterations in action potential characteristics that resulted in increased firing rate and excitability of the hDBB neurons also were produced by application of charybdotoxin. Neurotensin effects on these properties were occluded by 2 - [(1 - 7 - chloro - 4 - quinolinyl) - 5 - (2, 6 - di - methoxyphenyl) pyrazol-3-yl) carbonylamino] tricyclo (3.3.1.1.)decan-2-carboxylic acid, a nonpeptide high-affinity neurotensin receptor antagonist. Neurotensin blockade of IC, possibly through ICa, is a potential physiological mechanism whereby this peptide may evoke alterations in the cortical arousal, sleep-wake cycle, and theta rhythm.     

The propensity for employee participation by electrical and mechanical trades in the construction industry

Using the four input-output tables compiled in Turkey to date, the aim of this paper is to examine the construction sector's role in the Turkish economy and analyse its relationships with the other sectors of the national economy. Analysis results show that the share of construction in Gross National Product (GNP) and National Income (NI) tend to increase whereas the GNP share of manufacturing is relatively stable and that of services tend to increase after an abrupt decrease in 1985; backward linkage indicators and output multipliers, as well as forward linkage indicators and input multipliers of construction industry are stable; and finally, direct and total construction inputs from manufacturing show relative stability and those from services tend to increase in recent years. These findings point out the similarities between the Turkish construction industry and some advanced industrial countries (AICs) like Japan and Italy showing signs of growing ‘maturity’ of the Turkish economy.     

Grafting of enzymes on collagen films using Woodward's reagent "K" and a water-soluble carbodiimide derivative

Two new methods of activation were developed to graft enzymes on collegen films. They involved chemical modifications of surface groups of collagen either by Woodward's reagent "K" or by EDC, a water-soluble derivative of carbodiimide. EDC was a better coupling agent and a detailed study was conducted with this agent. It could be used either in a global method of activation and coupling, or in a two-step procedure of activation of collagen, followed by spontaneous coupling of enzyme. All enzymes tested were successfully bound: malate dehydrogenase, lactate dehydrogenase, aspartate aminotransferase, urease, creatine kinase, hexokinase. The influence on the yield of grafted enzyme, of pretreatment of films, time and temperature of EDC activation, concentration of EDC and enzyme, protecting agents was studied. Stability of enzyme activity on storage was greatly increased after grafting. A co-grafted dual system creatine kinase/heoxkinase, was achieved which exhibited a good efficiency. A striking renaturing process at 0-4degreesC after thermal denaturation, was observed with hexokinase.     

Development and evaluation of a Driving Observation Schedule (DOS) to study everyday driving performance of older drivers

This paper describes the development and evaluation of an on-road procedure, the Driving Observation Schedule (DOS), for monitoring individual driving behavior. DOS was developed for use in the Candrive/Ozcandrive five-year prospective study of older drivers. Key features included observations in drivers’ own vehicles, in familiar environments chosen by the driver, with start/end points at their own homes. Participants were 33 drivers aged 75+ years, who drove their selected route with observations recorded during intersection negotiation, lane-changing, merging, low speed maneuvers and maneuver-free driving. Driving behaviors were scored by a specialist occupational therapy driving assessor and another trained observer. Drivers also completed a post-drive survey about the acceptability of DOS. Vehicle position, speed, distance and specific roadways traveled were recorded by an in-vehicle device installed in the participant's vehicle; this device was also used to monitor participants’ driving over several months, allowing comparison of DOS trips with their everyday driving. Inter-rater reliability and DOS feasibility, acceptability and ecological validity are reported here. On average, drivers completed the DOS trip in 30.48 min (SD = 7.99). Inter-rater reliability measures indicated strong agreement between the trained and the expert observers: intra-class correlations (ICC) = 0.905, CI 95% 0.747–0.965, p < 0.0001; Pearson product correlation, r (18) = .83, p < 0.05. Standard error of the measurement (SEM), method error (ME) and coefficient of variation (CV) measures were consistently small (3.0, 2.9 & 3.3%, respectively). Most participants reported being ‘completely at ease’ (82%) with the driving task and ‘highly familiar with the route’ (97%). Vehicle data showed that DOS trips were similar to participants’ everyday driving trips in roads used, roadway speed limits, drivers’ average speed and speed limit compliance. In summary, preliminary findings suggest that DOS can be scored reliably, is of feasible duration, is acceptable to drivers and representative of everyday driving. Pending further research with a larger sample and other observers, DOS holds promise as a means of quantifying and monitoring changes in older drivers’ performance in environments typical of their everyday driving.