Tc Ratio Research Articles

Adsorption behavior of 99Tc on Fe, Fe2O3 and Fe2O4

The adsorption of 99Tc on the adsorbers Fe, Fe2O3 and Fe3O4 was studied by batch experiments under aerobic and anoxic conditions. The effects of pH and CO32- concentration of the simulated ground water on the adsorption ratios were also investigated, and the valences of Tc in solution after the adsorption equilibrium were studied by solvent extraction. The adsorption isotherms of TcO4- on the adsorbers Fe, Fe2O3 and Fe3O4 were determined. Experimental results have shown that the adsorption ratio of Tc on Fe decreases with the increase of pH in the range of 5-12 and increases with the decrease of the CO32- concentration in the range of 10-8M-10-2M. Under aerobic conditions, the adsorption ratios of 99Tc on Fe2O3 and Fe3O4 were not influenced by pH and CO32-concentration. When Fe was used as adsorbent, Tc existed mainly in the form of Tc(IV) after equilibrium and in the form of Tc(VII) when the adsorbent was Fe2O3 or Fe3O4 under aerobic conditions. The adsorption ratios of Tc on Fe, Fe2O3 and Fe3O4 decreased with the increase of pH in the range of 5-12 and increased with the decrease of the CO32- concentration in the range of 10-8M-10-2M under anoxic conditions. Tc existed mainly in the form of Tc(IV) after equilibrium when Fe, Fe2O3 and Fe3O4 was the adsorbent under anoxic conditions. The adsorption isotherms of TcO4- on the adsorbers Fe, Fe2O3 and Fe3O4 are fairly in agreement with the Freundlich’s equation under both aerobic and anoxic conditions.

Photoswitch based on remarkably simple naphthopyrans

Photochromic switches built around 5-carbonyl-3,3-diphenyl-3 H-naphtho[2,1- b]pyran unit have been synthesized. Their open forms are constituted of a 1:1 ratio of TC and TT-isomers according to 19F and 1H NMR investigations. Electrocyclization of TT isomers back to the closed form is efficiently achieved upon visible irradiation whereas it has been found to be a particularly unfavoured thermal process. These simple 2H-chromenes could act as molecular photoswitch at ambient temperature.

Simulated Impacts of Tournament-Associated Mortality on Largemouth Bass Fisheries

Abstract We used creel survey data combined with a simulation model to assess how tournament-associated mortality could increase exploitation of largemouth bass Micropterus salmoides and influence largemouth bass fisheries. We obtained estimates of total largemouth bass harvest (HARV) and total tournament catch (TC, i.e., the number of fish brought to judging stations) at nine lakes from Arkansas, Florida, and Texas. The ratio of TC to HARV exceeded 1.0 at five of the nine lakes studied and ranged from 0.35 to 5.18. We simulated potential tournament-associated mortality rates ranging from 0% to 70% applied to TC fish. Because exploitation was not known, we modeled harvest estimates to represent four potential exploitation rates (5, 15, 25, and 35%). The age-structured simulation model predicted that at three of nine lakes where TC/HARV ratios exceeded 3.0, tournament-associated mortality rates of 20–30% could cause 5–12% declines in the abundance of largemouth bass larger than 300 mm total length and resu...

Recovery of sterols as fatty acid steryl esters from waste material after purification of tocopherols

Tocopherols are purified industrially from soybean oil deodorizer distillate by a process comprising distillation and ethanol fractionation. The waste material after ethanol fractionation (TC waste) contains 75% sterols, but a purification process has not yet been developed. We thus attempted to purify sterols by a process including a lipase-catalyzed reaction. Candida rugosa lipase efficiently esterified sterols in TC waste with oleic acid (OA). After studying several factors affecting esterification, the reaction conditions were determined as follows: ratio of TC waste/OA, 1:2 (wt/wt); water content, 30%; amount of lipase, 120 U/g-reaction mixture; temperature, 40 degrees C. Under these conditions, the degree of esterification reached 82.7% after 24 h. FA steryl esters (steryl esters) in the oil layer were purified successfully by short-path distillation (purity, 94.9%; recovery, 73.1%). When sterols in TC waste were esterified with FFA originating from olive, soybean, rapeseed, safflower, sunflower, and linseed oils, the FA compositions of the steryl esters differed somewhat from those of the original oils: The content of saturated FA was lower and that of unsaturated FA was higher. The m.p. of the steryl esters synthesized (21.7-36.5 degrees C) were remarkably low compared with those of the steryl esters purified from high-b.p. soybean oil deodorizer distillate substances (56.5 degrees C; JAOCS 80, 341-346, 2003). The low-m.p. steryl esters were soluble in rapeseed oil even at a final concentration of 10%.

Sources of interference in field studies of diesel exhaust emissions.

This article describes interferences encountered in a variety of occupational settings during industrial hygiene surveys of diesel particulate material (DPM) using the NIOSH 5040 Method. The method yields time-weighted-average measurements of elemental carbon (EC), organic carbon (OC), and total carbon (TC = EC + OC). NIOSH recommends EC as proxy for DPM, but other agencies (e.g., MSHA) regulate exposure as TC. Surveys were conducted in an engine factory and a wood treatment plant where diesel equipment was used, and in a foundry where its use was being considered. Full shift samples were collected using open-faced cassettes and cyclones fitted with 37-mm quartz fiber filters analyzed by the NIOSH 5040 Method. Non-DPM-related interferences were noted for both the OC and EC. In the engine factory and wood treatment facility, OC measurements were very high (range of 10.0-1600 microg/m(3)), while EC levels were mostly below the LOD. These findings almost certainly reflect interferences by cutting oil mists and airborne creosote respectively. In the foundry, EC levels were high and comprised mainly of larger (>4 microm) particles (open face samples: arithmetic mean = 136 microg/m(3), geometric mean = 74.0 microg/m(3); cyclone samples: arithmetic mean = 30.2 microg/m(3), geometric mean = 14.7 microg/m(3)). These findings suggest that OC interferences should be suspected if the EC:TC ratio is <0.35 and, if DPM surveys are performed with open-faced samplers, at least a small number of size-selective samplers should be employed to assure that results do not reflect EC interference by larger (i.e., >1-4 microm) particles. They also support the ACGIH decision to modify its proposed DPM TLV to specifically consider elemental carbon, rather than total carbon.

The transcobalamin (TC) codon 259 genetic polymorphism influences holo-TC concentration in cerebrospinal fluid from patients with Alzheimer disease.

Two proteins bind vitamin B12 in plasma: haptocorrin (transcobalamin I) and transcobalamin (transcobalamin II; TC). The latter is the critical transporter that delivers vitamin B12 to peripheral tissues. TC carries one-third of the circulating B12 (holo-TC), but most TC is unsaturated (apo-TC) (1)(2). Polyacrylamide gel electrophoresis has revealed two common TC isotypes, M and X, and two rare variants, S and F (3)(4), that may influence the cellular availability of vitamin B12 (5)(6). The phenotypic variability is a multifactorial phenomenon that probably includes cell-type-specific processing of translated TC (5), but the substitution of proline (P) for arginine (R) at codon 259 of the TC gene is the major determinant of the TC variability, at least in Caucasians (5)(7), and affects TC concentrations in plasma (5)(8). Most 259PP individuals have the TC M phenotype, whereas most 259RR individuals have the X phenotype. Vitamin B12 is essential for the function of the central nervous system (CNS) (9). Little is known about vitamin B12 transport in the human brain, but early in vitro data indicate that TC plays a central role (10). Cerebrospinal fluid (CSF) contains both haptocorrin and TC, with the latter predominating (11). The CSF:plasma ratio of TC is high compared with other plasma proteins (12), which suggests an active transport mechanism or synthesis by cells in the CNS. Cultured astrocytes have been shown to produce and secrete TC in vitro (13), indicating that at least some of the TC in CSF originates from within the CNS. However, because vitamin B12 is not synthesized in human cells, it must enter the brain and CSF from the blood across the blood–brain barrier, conceivably via interaction between holo-TC and the TC receptor. In the present investigation, …

Sex and time differences in the associations of non–high-density lipoprotein cholesterol versus other lipid and lipoprotein factors in the prediction of cardiovascular death (The Rancho Bernardo Study)

Non–high-density lipoprotein (HDL) cholesterol (total cholesterol [TC] minus HDL cholesterol) has been suggested as the preferred lipid fraction to predict cardiovascular disease. We compared the ability of lipids, lipoproteins, the ratio of total to HDL cholesterol (TC/HDL), and non-HDL cholesterol to predict fatal coronary heart disease (CHD) and cardiovascular disease in 1,386 women and 1,094 men (mean age 69 years). After 10 years, there were more deaths in men (n = 310) than women (n = 268), but the proportions of deaths attributed to CHD (23% and 25%, respectively) and cardiovascular disease (48% and 47%) were similar. In men, age-adjusted values for non-HDL cholesterol, TC/HDL ratio, and triglycerides each predicted a significantly increased risk of CHD and cardiovascular disease; none of these associations was independent of pack-years of smoking, systolic blood pressure, fasting plasma glucose, body mass index, and physical activity. In women, age-adjusted non-HDL cholesterol levels did not predict CHD or cardiovascular disease events before or after adjusting for these covariates and for estrogen replacement therapy. In women, only the ratio of TC to HDL cholesterol predicted CHD and cardiovascular disease deaths independent of estrogen use and other risk factors. Observed associations were sensitive to time, being evident in women at 3 and 5 years, and lost thereafter, but not apparent before 10 years in men. Thus, non-HDL cholesterol is not superior to individual lipids, lipoproteins, or their ratios in the prediction of cardiovascular death in older adults.

Lurgi develops new propylene process

Abnormal lipid metabolism manifests as hypercholesterolemia in patients with obstructive jaundice due to lipoprotein X (LpX). Our aim was to explore the clinical laboratory characteristics of patients with obstructive jaundice accompanied by dyslipidemia in a large number of samples.A total of 665 patients with obstructive jaundice were included and categorized into two groups (with/without dyslipidemia) based on the ratio of the sum of HDL-c and LDL-c to total cholesterol [(HDL-c + LDL-c)/TC] with a cut-off value of 0.695. Laboratory liver, kidney, and blood lipid parameters were determined. Cholesterol composition assessment was performed by ultracentrifugation and high-performance liquid chromatography (UC-HPLC), and serum protein profiles were analyzed by capillary electrophoresis.Liver function in patients with obstructive jaundice accompanied by dyslipidemia was more aggravated than that in patients with simple obstructive jaundice (P < 0.05). The (HDL-c + LDL-c)/TC ratio was negatively correlated with bilirubin levels (P < 0.05). In addition, the difference in ApoB/LDL-c ratios was statistically significant between the obstructive jaundice accompanied by dyslipidemia group and healthy control group (P < 0.05). The LDL-c concentration determined by the UC-HPLC method was more than five times that determined by the enzymatic method (P < 0.05). Bisalbuminemia was found in 43 of 60 patients with obstructive jaundice accompanied by hypercholesterolemia.In patients with obstructive jaundice, the decreased (HDL-c + LDL-c)/TC ratio may be a novel marker to identify dyslipidemia secondary to LpX. The decreased ratio was associated with poor liver function and indicated disease progression.

Atherosclerotic plaque morphology and coronary thrombi

Detailed analysis of coronary lesions from patients with sudden coronary death provides insights into the correlations among sex, coronary risk factors, and patient activity with specific plaque morphologies. In men, acute plaque rupture with thrombus and increased numbers of plaques prone to rupture are associated with elevations in total serum cholesterol, low HDL-C, and an increased ratio of TC to HDL-C. Sudden death related to exercise in men is linked to acute plaque rupture, thinner fibrous caps, increased frequency of plaque hemorrhage, increased vasa vasorum, and more abnormal lipid levels compared with sudden death at rest. Acute plaque rupture in women older than 50 years is also associated with an elevated TC. In women younger than 50 years, plaque erosion, a pathologic entity that is distinct from plaque rupture, accounts for the vast majority of coronary thrombi and correlates with cigarette smoking. In contrast to plaque rupture, plaque erosion is not associated with abnormal lipid levels. Acute coronary plaque rupture or erosion does not invariably result in death, and repetitive healing of ruptures and erosions is a mechanism of stenosis progression in coronary atherosclerosis. Knowledge of pathologic characteristics should help nuclear cardiologists to identify suitable targets and develop appropriate targeting agents.

Pseudogap influence on the 2 Δ(0)/ Tc ratio in d-wave superconductors

We study the possibility of a superconducting phase in a system whose normal state is characterized by the presence of a pseudogap in the energy spectrum at temperatures below a characteristic value T *. By rewriting the Gorkov equations we developed a phenomenological model in order to calculate the effects of the pseudogap on superconducting state properties such as the superconducting gap at T=0, Δ(0), the superconducting critical temperature, T c, and the R=2 Δ(0)/ T c ratio.

Solvent extraction of Tc(VII) by the mixture of TBP and 2-nitrophenyl octyl ether

The extraction of Tc(VII) by the mixture of tri-n-butyl phosphate (TBP) and 2-nitrophenyl octyl ether (NPOE) has been studied. 0.2M NPOE-TBP can extract Tc(VII) effectively from 1M HNO3 and 1M NaOH solutions with distribution ratios of 57.1 and 12.3, respectively. The distribution ratio of Tc(VII) decreases with increasing (>0.5M) HNO3 concentration but increases with the increase of NaOH concentration. A pH 9 NaOH solution has proven to be suitable for Tc(VII) stripping. A simple extraction-stripping cycle can remove Tc(VII) from a sodium hydroxide solution. A more sophisticated extraction process is proposed to remove Tc(VII) from nitric acid solution because the co-extracted HNO3 prevents the direct stripping of Tc(VII) by NaOH solution of pH 9.

Lattice model of living polymerization. III. Evidence for particle clustering from phase separation properties and “rounding” of the dynamical clustering transition

Equilibrium polymerization is studied here as a prototype for clustering transitions that commonly occur in systems of interacting particles at equilibrium. These transitions are often difficult to locate because of transition “rounding” associated with a limited extent of cluster growth, competing association or dissociation processes that initiate or inhibit clustering, and other constraints on the particle clustering dynamics. Instead of singularities in thermodynamic and transport properties, more subtle property changes signal the onset of particle clustering, explaining why clustering transitions are often overlooked or misinterpreted. We utilize a Flory–Huggins model for the equilibrium (“living”) polymerization of linear polymer chains to identify experimental signatures (features in the osmotic pressure, osmotic compressibility, and specific heat) that can be used to locate and quantify the transition “rounding” in general clustering transitions. The computation of a flattening in the concentration dependence of the osmotic pressure in the one-phase region motivates our consideration of the temperature dependence of the second virial coefficient and the variation of the theta temperature Tθ with “sticking energy” Δh as possible important indicators of particle clustering. The ratio of the critical temperature Tc for phase separation to Tθ, along with other “critical constant” ratios, such as the osmotic compressibility factor Zc, are also calculated and discussed in connection with establishing criteria for identifying particle clustering transitions and for quantifying the relative “strength” of these transitions.

The quantification of technetium in generator-derived pertechnetate using ICP-MS

Previous analytical methods employed to measure 99 Tc: 99 m Tc ratios in chromatographic 99 m Tc generators, derived from fission-based 99 Mo , were limited in monitoring the ratios in low activity generators, over the extent of their elution regimes. For regulatory purposes, ICP-MS was employed to measure total technetium in generator eluates down to a level of 200 pg ml −1 (200 ppt). Measured 99 Tc: 99 m Tc ratios compared very well with the theoretically computed values, ranging from 47:1 for a first elution of a generator with a long ingrowth time to 1.4:1 for the 17th elution of a generator with a short ingrowth time.

Effect of a temperature dependent effective quasiparticle mass on the surface impedance of YBa 2 Cu 3 O 7-x

The temperature dependent surface impedance Zs(T) of single-crystalline YBa2Cu3O7-x (YBCO) was analyzed within the two-fluid model in terms of the fraction of paired charge carriers, fs(T), and of the quasiparticle scattering time. The usual approach was extended by considering a temperature dependent effective quasiparticle mass m*(T), which results from a strong electron-phonon interaction. This effect must not be neglected in the description of high-temperature superconductors due to the large ratio of Tc to the Debye temperature TD. The temperature dependence of the penetration depth, of high-quality YBCO crystals and films could be described with an electron-phonon coupling constant, and using fs(T) = 1- (T/Tc)2.8 as an approximation of the BCS theory. Different trial phonon spectra were encountered in terms of their ability to reproduce the -data. The scattering time was described by the Bloch-Gruneisen formalism with TD=460 K. Assuming an Einstein spectrum with, a residual resistivity and a fraction of unpaired quasiparticles at T = 0 K yielded a surprisingly good agreement of the model with Zs(T)-data measured at 87 GHz with a high-quality epitaxial YBCO film between T=4 K and Tc. While an exact reproduction of the surface impedance asks for a rigorous theoretical computation, our analysis demonstrates that strong electron-phonon coupling is relevant for discussing the unconventional transport properties of YBCO.

Solvent extraction of technetium(VII) by cyclic amides

The extraction behavior of heptavalent technetium with cyclic amides inn-dodecane from nitric acid solution was studied. The amides investigated are N-(2-ethyl)hexylbutyrolactam(EHBLA). N-(2-ethyl)hexylvalerolactam(EHVLA), N-(2-ethyl)hexyl-caprolactam (EHCLA), N-octylcaprolactam(OCLA), a mixture of 3-octyl-N-(2-ethyl)hexylvalerolactam and 4-octyl-N-(2-ethyl)hexylvalerolactam (3,4,OEHVLA), 2-octyl-N-(2-ethyl)hexylcaprolactam(2OEHCLA), a mixture of 3-octyl-N-(2-ethyl)hexylcaprolactam and 5-octyl-N-(2-ethyl)hexylcaprolactam(3,5,OEHCLA) and that of 3-octyl-N-octylcaprolactam and 5-octyl-N-octylcaprolactam(3,5,OOCLA). From the results of the distribution ratio of Tc(VII) as a function of acid concentration, cyclic amides concentration and HTcO4 concentration, the effects of both the ring size of cyclic amide and structure of the substituents attached to different positions of the cyclic ring on the extraction behavior of Tc(VII) were discussed. A clear steric hindrance was observed. For applications, 3,4,OEHVLA is proposed as the best extractant for Tc from acidic solution.

Inbred mouse strains differ in the regulation of startle and prepulse inhibition of the startle response.

The startle response and adaptability of the startle response (prepulse inhibition and habituation) have been observed in animals. The studies reported here screened 8 inbred mouse strains to determine whether genetic factors influence these behaviors. Strain differences were found in both the sensitivity to acoustic startle and the magnitude of both the auditory and tactile startle as well as the magnitude of prepulse inhibition (PPI) of both tactile and acoustic startle. Neither the 2 startle responses nor the 2 forms of PPI were significantly correlated with one another, suggesting that different genes regulate these 2 forms of startle and PPI. Acoustic-acoustic PPI was significantly correlated, however, with hippocampal auditory gating (TC ratio) suggesting an overlap in the genes that regulate these 2 forms of sensory gating.

The properties of co-sputtered YBa2Cu3O7 and CeO2 thin films

We have investigated the morphology and superconducting properties of off-axis co-sputtered thin films of YBa2Cu3O7 and CeO2. The composite films were made with CeO2 concentrations up to approximately 43%. Morphology investigations using x-ray diffraction and scanning electron microscopy suggest that films with less than 29% CeO2 may consist of a distorted YBCO crystal structure with Ce being incorporated into the lattice. Films with more than 29% consist of a new material phase. Tc and resistance ratio decreased with increasing CeO2 concentration. Degradation of Tc after photoresist processing was observed for films with higher amounts of CeO2. However, this degradation was reversed and Tc improved beyond that of the as-deposited film by processing the films with an oxygen plasma etch. The temperature dependence of the critical current near Tc showed two power law dependence regions with a crossover near 0.99 Tc for films having low concentrations of CeO2. This crossover shifted to lower temperatures for films with higher amounts of CeO2. Ic’s were decreased by small applied magnetic fields, and for some samples response was observed which was greater than 0.5 mA/G and increased with decreasing temperature. For a sample having 26% CeO2, a 40% reduction in critical current for a 2 G applied field was observed. These magnetic field responses indicate that this material may be a promising candidate for the development of Josephson vortex flow devices.

Extraction characteristics of pertechnetate with tetraphenylarsonium in the presence of chloride, nitrate and perchlorate anions

Selected extraction systems of TcO 4 − −(H,Na)A−H2O/R(TcO4,A)−CHCl3, C6H5NO2 type, where A=Cl−, NO 3 − , ClO 4 − , R=(C6H5)4As+, were studied. The solvent extraction of sub- and super-stoichiometric ratio of Tc∶R was performed. The solubility of (C6H5)4AsTcO4 in water, chloroform and nitrobenzene were determined too. The results of the extractions are presented in the form of TcO 4 − distribution dependencies on the phase composition and the extraction constants of individual TcO 4 − , Cl−, NO 3 − , ClO 4 − anions and TcO 4 − -Cl−, TcO 4 − −NO 3 − , TcO 4 − −ClO 4 − ion pairs.

The effect of physical activity on serum total and low-density lipoprotein cholesterol concentrations varies with apolipoprotein E phenotype in male children and young adults: The cardiovascular risk in young finns study

Apolipoprotein E (apo E) determines serum total (TC) and low-density lipoprotein (LDL-C) cholesterol concentrations and is thus associated with coronary heart disease (CHD) risk. We studied if the effect of physical activity (PA) on serum TC and LDL-C concentrations varies with apo E phenotype in a population-based sample of children and young adults with regular PA. The study cohort consisted of subjects aged 9, 12, 15, 18, 21, and 24 years in 1986 (N = 1,498) participating in a large multicenter study of cardiovascular risk factors in children and young adults. Serum lipid concentrations were determined enzymatically, and apo E phenotypes by isoelectric focusing and immunoblotting. The composition of the diet was determined by a 48-hour recall method, and a PA index was calculated on the basis of frequency, intensity, and duration of activity assessed by a questionnaire. LDL-C ( P = .0082), TC ( P = .014), and the high-density lipoprotein cholesterol (HDL-C)/TC ratio ( P = .0004) responses to exercise varied with apo E phenotype. The effect of PA on LDL-C, TC, or HDL/TC was not found in apo E phenotype E4/4. A moderate inverse effect of PA on TC and LDL-C and a positive effect on HDL/TC was found in subjects with E4/3 and E3/3 phenotypes. Similar but stronger associations were found between these variables within the group of E3/2 males. The effect of PA on serum lipid levels was strongest within the phenotype E3/2. These associations were not explained by dietary habits. Apo E phenotype partly determines the effect of PA on serum TC and LDL-C in Finnish male children and young adults with regular PA.

The superconducting gap ratio, isotope-shift exponent and pressure coefficient of Tc for high- Tc systems

The superconducting gap ratio, isotope-shift exponent and the pressure co-efficient of the superconducting transition temperature are studied within different models proposed for high- T c cuprate oxide systems. A comparison with the experimental results of high- T c oxide systems is made.