Averaged cross sections for the reactions (68)Zn(n,p)(68g)Cu and (68)Zn(n,p)(68m)Cu for a (235)U fission neutron spectrum.

Making use of the method developed in our laboratory for the simultaneous determination of cross sections leading to both the ground and metastable states, we have measured the (68)Zn(n,p)(68g)Cu and (68)Zn(n,p)(68m)Cu reactions, using Zn enriched to 99.4% in its isotope (68)Zn. The measured cross sections are (15.04+/-0.35) and (3.69+/-0.30)microb for the ground and metastable state, respectively. However, a direct determination of the cross section leading to the metastable state gives a value of (4.75+/-0.38)microb. A possible reason for this discrepancy-which is outside experimental uncertainties-is that some tabulated values used in our calculations for the decay parameters of (68g)Cu and (68m)Cu, have either larger than quoted, or unknown systematic, uncertainties.     

In vivo energy dispersive X-ray fluorescence for measuring the content of essential and toxic trace elements in teeth.

The calibration and application of a facility, based on energy dispersive X-ray fluorescent analysis (EDXRF) using 109Cd as an excitation source, for in vivo and in vitro estimation of Ca, Pb, Sr and Zn in tooth enamel is described. During the in vivo measurements, the device ensures tissue protection of face and mouth cavity from radiation, and only a small part of tooth surface under study is irradiated. To calibrate the facility, the contents of Ca, Sr and Zn were analyzed simultaneously in the enamel of 50 teeth by EDXRF and instrumental neutron activation analysis (INAA). Standards prepared from powdered tooth enamel with additions of chemically pure lead compounds were used to calibrate for lead graduation. Enamel calcium is suggested as an internal standard during in vivo EDXRF of teeth. The content of enamel Sr, Zn and Pb was determined by EDXRF in 35 permanent intact teeth of teenagers and adults. It was shown that lead concentration didn't exceed 3 micrograms/g for all the teeth.     

Effect of mass, oxidation state and duration of chronic ingestion on plutonium absorption in fed rats

The effects of time, mass and oxidation state on plutonium gastrointestinal absorption and tooth adsorption were studied during and after chronic ingestion of plutonium-238 (IV) or (VI) (1.55-15.60 kBq/ml) in 6.5 mM bicarbonate medium by fed rats via drinking water for 8 days to 3 months. Animals were killed during the ingestion to follow the kinetics of whole-body storage and clearance of plutonium. At 1.55 kBq/ml the amount of plutonium retained in the skeleton increased continuously during the 85 days of ingestion and reached a plateau thereafter. This plutonium retention was therefore dependent on the total mass administered but not proportional to this mass, as the fraction of administered plutonium retained decreased during the first 22 days of ingestion and then stabilized. This is reflected by the gastrointestinal transfer (f1), which had risen to (3.80 +/- 0.82) x 10(-5) on Day 3 of ingestion and then decreased to a stabilized value of (1.07 +/- 0.06) x 10(-5) from Day 30 to the end of the ingestion period. In the liver, the amount of plutonium retained reached a plateau, which lasted from Day 30 to the end of ingestion. The kidneys and spleen were also found to be retention sites. By Day 3 of ingestion, for a mass ingested of 5 x 10(-7) g/kg of body mass, the maximum mean value of f1 we found was smaller than the 10(-4) recommended by ICRP Report 30. The oxidation state had no effect on f1. Large plutonium deposition was observed on the teeth. For both oxidation states (IV) and (VI), about 0.10% of the administered dose was deposited on the teeth after 3 days of ingestion, whatever the plutonium concentration administered. However, whereas the amount of plutonium (IV) deposited did not change throughout the ingestion period, tooth deposition of plutonium (VI) decreased.     

Reproducibility and accuracy of measuring unerupted teeth using limited cone beam X-ray CT

OBJECTIVE: The purpose of this investigation was to determine the reproducibility among observers and accuracy of the measurement of the tooth crown width of unerupted teeth using limited area cone beam X-ray CT. METHODS: 3DX multi-image micro-CT (3DX, Morita Co., Kyoto, Japan) images of impacted supernumerary teeth in the median maxillary region taken prior to extraction were used for the samples. The width of the tooth on the 3DX image was measured five times by five individual observers. Significant differences in values among the observers in the measurement were determined by one-way analysis of variance for examining reproducibility. The measurement results of the ten samples on 3DX images were compared with the laboratory measurements using a three-dimensional co-ordinate measuring apparatus, using the Wilcoxon signed-rank sum test. RESULTS: There was no significant difference among the observers in the measurement (P>0.05). The measurement results shown on 3DX images were significantly larger than those of the laboratory measurements (P<0.05). The mean difference was +0.088 mm. CONCLUSIONS: 3DX has high reproducibility for measuring the tooth crown width of unerupted teeth. While 3DX measurement values were larger than the laboratory measurements, the difference is clinically insignificant.     

中国优秀运动员血清锌、铜水平的研究

为研究参加系统训练运动员冬春两季的血清锌、铜水平的变化及影响因素,作者对9个运动项目360名优秀运动员测定了血清锌、铜水平。结果表明:运动员在冬训期的血清锌水平偏低、血清铜水平偏高,18岁以下的运动员血清铜低于成年运动员。25名优秀运动员冬春两季血清锌、铜水平配对T检验的数据表明,女运动员在冬季时的血清锌远低于春季时的水平。本文数据为运动员微量元素的合理补充提供了依据。     

Correlation of R2 with total iron concentration in the brains of rhesus monkeys

PURPOSE: To estimate the relationship between R2 = 1/T2 as measured with a double echo spin echo sequence and total iron concentration in gray matter structures in the brains of aging rhesus monkeys. MATERIALS AND METHODS: Using a 1.5-T magnetic resonance (MR) imager, we collected double echo spin echo images of the brains of 12 female rhesus monkeys aged between 9 and 23 years. From the double echo images, the transverse relaxation rate R2 = 1/T2 was calculated in selected gray matter regions. After the animals were euthanized, their brains were excised and tissue punches were taken of the substantia nigra, globus pallidus, and gray matter regions of the cerebellum. Some of the tissue punches were assayed for total iron using atomic absorption spectroscopy. RESULTS: The range of tissue iron concentration spanned from 15 to 450 microg/g wet weight, with the highest levels in the globus pallidus and the lowest levels in the cerebellum. The results show that R2 was highly correlated with the total iron concentration and that the relationship between R2 and tissue iron concentration appeared to depend upon the iron concentration. For concentrations above approximately 150 microg/g wet weight, R2 increased with a sensitivity of 0.0484 +/- 0.0023 second(-1)(microg/g)(-1). In contrast, where the iron concentration was below 150 microg/g, R2 increased at 0.0013 +/- 0.0073 second(-1)(microg/g)(-1). The bilinear behavior may reflect changes with age in the relative amounts of iron distributed diffusely and in granular form in the globus pallidus and substantia nigra. Histological sections of the tissues stained for iron and ferritin support this hypothesis and indicate that the distribution of ferritin is similar to the distribution of iron. CONCLUSION: This study reaffirms the value of measuring the MR relaxation rate R2 for a noninvasive estimate of iron content in the brain and identified limitations in the relationship at low tissue iron concentrations.     

Release of muscle proteins after downhill running in male and female subjects

The release of muscle proteins after downhill running, which mainly includes eccentric muscle action, was compared in females (F; n=9) and males (M; n=9). They performed 20 min of downhill treadmill running with 16% decline with a target heart rate of 70% of the individual VO2peak, which was determined two weeks before. Blood samples were drawn before, 6 and 24 h after exercise to measure plasma levels of skeletal troponin I (sTnI), myosin heavy chain fragments (MHC), creatine kinase (CK), and myoglobin (Mb). Baseline levels before exercise were significantly higher in males compared to females for the cytoplasmic proteins CK and Mb, but the difference for MHC and sTnI was not significant. Both groups displayed marked and significant early (6 h) increases (P<0.05) for sTnI (median: F: 8.2 microg/L; M: 22.0 microg/L), Mb (median: F: 86.8 microg/L; M: 407 microg/L), and CK (median: F: 162 U/L; M: 339 U/L). A significant (P<0.05) but delayed (24 h) increase was found for MHC (median: F: 482 microU/L; M: 651 microU/L). The absolute values for all four parameters were significantly (P<0.05) higher in males compared to females; however, no difference was found for the relative increases and the time course of all parameters between females and males. We conclude 1) that there were no significant differences in the basal concentrations of predominantly bound proteins, and 2) that there were no differences in the relative muscle protein release between females and males before and after one bout of high-intensive eccentric exercise. The higher plasma concentrations of all measured muscle proteins in males are probably caused by the higher muscle mass compared to females.     

ESR dating at K and X band of northeastern Brazilian megafauna.

The archaeological dose (AD) was measured in three tooth samples of giant mammals that belonged to Brazilian megafauna using electron spin resonance (ESR) spectroscopy at X-band (nu approximately 9.5 GHz) and K-band (nu approximately 24 GHz). Samples were collected in Lagoa de Dentro, Puxinan? city in Paraiba, a northeast state in Brazil and were identified as Haplomastodon waringi (Holland) (two teeth) and one tooth sample of Xenorhinotherium bahiense (Cartele and Lessa). The average AD led to an age for the Haplomastodon samples of 11.6 ky bp. For one sample (Haplomastodon) K-band was also employed to evaluate the AD. The K-band spectrum had three components, determined using spectral simulation as follows: a wide isotropic line with g factor 2.0048, an orthorhombic line with g(x)=2.0034, g(y)=2.0022 and g(z)=1.9974, and another isotropic line with g factor 2.0008. The amplitude of these three signals increase with the added dose and the average dose found was 26+/-5 Gy. This result is compatible with the AD determined with X-band 21+/-3 Gy.     

Increased body iron stores in elite road cyclists

BACKGROUND: One third of French elite road cyclists were found to have hyperferritinemia on antidoping control tests performed during the Tour de France in 1998. PURPOSE: This study was undertaken to determine whether hyperferritinemia corresponded to elevated body iron stores or not and, affirmatively, what were its mechanism, its clinical consequences, and its spontaneous course. METHODS: 83 elite road male cyclists presenting with hyperferritinemia, defined as serum ferritin level greater than 300 microg.L-1, were studied with respect to consumption of iron and other drugs, serum iron tests, HFE mutations, and hepatic iron concentration (HIC; N < 35 micromol.g-1 dry weight). RESULTS: All cyclists were asymptomatic and had normal physical and cardiac examination. Their median (range) serum ferritin, serum iron, and transferrin saturation levels were 504 microg.L-1 (306-1671), 20 micromol.L-1 (8.5-36.3), and 39% (20-76), respectively. HIC was increased in 24/27 up to 187 micromol.g-1. Allelic frequency of the H63D mutation was increased in cyclists when compared to controls (P = 0.04). However, iron tests did not differ according to HFE genotypes. Most cyclists (89%) had been supplemented with iron. The median iron supplementation was 25.5 g (range: 1.4-336) and correlated well (P = 0.002) with serum ferritin. Evolution of serum ferritin levels did not differ whether cyclists had been continuing iron supplementation or not. CONCLUSION: Hyperferritinemia in elite road cyclists accounted for increased body iron stores caused by and persisting after cessation of excessive iron supplementation. Even when mild, iron excess may expose to long-term complications and should be removed, at least at the time when professional cyclists retire. To prevent iatrogenic iron overload, supplementation with iron must be done according to serum ferritin follow-up and not either blindly or on the basis of serum iron determination only.     

Age estimation from pulp/tooth area ratio (PTR) in an Indian sample: A preliminary comparison of three mandibular teeth used alone and in combination

Pulp/tooth area ratio (PTR) method of adult dental age estimation has been examined on few tooth types. We assessed the lateral incisor (LI) and first premolar (PM1) in addition to canine (C) - alone and in combination. Periapical radiographs from 61 Indians aged 21-71 years were examined. PTR of LI produced the best age correlation (r?=?-0.395) followed closely by PM1 (r?=?-0.362). The canine revealed the lowest correlation (r?=?-0.206); among tooth combinations, the three teeth taken together had the best R value (-0.438) followed by LI?+?PM1 (-0.435), LI?+?C (-0.406) and C?+?PM1 (-0.37). The standard errors of estimates (S.E.E.) of the regression analyses for the individual teeth and tooth combinations ranged from ±12.13 to 13.08 years, indicating minimal difference in age estimates using solitary or multiple teeth. Errors were higher than in European groups (±2.5-5 years) which may partly owe to moderate age correlation of secondary dentine deposition in Indians. Moreover, facial soft-tissue superimposition in living subjects evaluated herein possibly precluded optimal tooth and pulp canal visualization. These indicate that the PTR method should be used judiciously in age estimation of living Indian adults, although further studies on larger samples with evenly distributed age-groups is necessary for deriving definitive conclusions.     

涡轮机分牙法与去骨法拔除男性下颌阻生第三磨牙的对比

 目的 比较涡轮机分牙法与去骨法对下颌阻生第三磨牙拔除术后反应的差异,为这类患牙的拔除方式选择提供参考。方法 选择门诊患者68位,共82颗患牙,随机分为两组,一组采用分牙法,另一组采用去骨法,每组41颗患牙。分牙法组使用涡轮机分牙法拔除患牙;去骨法组使用涡轮机去骨法拔除患牙。比较两组手术时间、术后疼痛、面部肿胀及张口受限程度的情况。结果 分牙法组手术时间为(23.5±6.4)min, 而去骨法组手术时间为(16.5±3.3)min,两组差异有统计学意义(P＜0.01);分牙法组术后疼痛及术后肿胀方面症状均轻于去骨法组,差别有统计学意义(P＜0.01);术后张口受限方面分牙法组和去骨法组比较,无统计学差别。结论 两种方法各有利弊,涡轮机分牙法可明显减轻术后疼痛和肿胀症状,但手术时间较长。     

A simple colorimetric method for determination of the specific activity of spallation-produced copper-67 using phenylglyoxal (PG) bis-(4N-methyl)thiosemicarbazone (TSC) derivatives

Copper-67 (⁶⁷Cu) is a useful radioisotope for therapeutic applications and is usually available from high-energy spallation of zinc targets. High-specific-activity ⁶⁷Cu is particularly important for radiolabelling antibodies for radioimmunotherapy. Since spallation-produced ⁶⁷Cu can also contain undesirable levels of nonradioactive copper (⁶³Cu and ⁶⁵Cu), which may interfere with antibody labeling, the availability of a simple inexpensive technique to determine the specific activity of ⁶⁷Cu would be useful. Bis-thiosemicarbazone (TSC) derivatives of 1,2-diketones or α-ketoaldehydes such as phenylglyoxal (PG) form orange-colored complexes with copper(II) that exhibit an absorption maximum at 480 nm (ext. coef. = 3-5 × 10³). A calibration curve was determined by analyzing a series of copper(II) chloride standards (0.1–40 μg/mL) prepared with excess PG-TSC in an ethanol-HCl-acetate buffer mixture. The standards were analyzed in duplicate and the resulting curve treated by least squares analysis (r = 1.00). Beer's law is observed up to about 40 μg/mL, and the lower limit of detection for this method using a Carey 219 spectrophotometer with a 1 cm cell path length is about 0.4 μg/mL. The PG-TSC derivative of zinc(II) chloride was also evaluated (100 fold excess) and was shown to have no interference on the 480 nm absorbance of the Cu(II) complex (2.5 μg/mL). Analysis of HCl target solutions of ⁶⁷Cu produced at the Brookhaven National Laboratory (one sample) and the Los Alamos Scientific Laboratory (four samples) by this method gave specific activity values which corresponded very well with values obtained by ion coupling plasma analysis (ICP). These results demonstrate that this simple technique can be used for the routine analysis of copper(II) solutions with no special sample preparation and with an u.v. spectrophotometer without waiting for radioactive decay of the test solution.     

两种根管修复治疗后牙牙体缺损的疗效比较

 目的 对比两种方法修复根管(全冠修复根管、高嵌体修复根管)用于后牙牙体缺损患者临床治疗的效果及预后状况。方法 选取2017-05至2019-05医院口腔科收治的后牙牙体缺损患者80例,按治疗方法分为两组,每组40例;A组行高嵌体修复根管治疗,B组行全冠修复根管治疗,分析患者缺牙修复效果、满意度、口腔健康状况改善情况等。结果 两组修复效果优良率分别为92.50%、95.00%,差异无统计学意义;B组满意度评分为(96.82±4.37)分,明显高于A组的(80.62±5.35)分,差异有统计学意义(t=14.362,P<0.05); B组治疗后修复体完整、与邻牙吻合、牙齿美观、咀嚼功能恢复患者构成比,治疗后口腔健康影响程度量表(oralhealthim pactprofile,OHIP-14)中各项评分,均明显优于A组,差异有统计学意义(P<0.05)。结论 全冠、高嵌体修复根管均可获得良好修复效果,但高嵌体修复根管对改善口腔健康状况及预后效果更好。     

急性心肌梗死MRI与心肌坏死标记物及心电图的相关性研究

目的 探讨心脏MRI确定的心肌梗死的梗死质量、梗死百分比、左心室功能等参数与肌酸激酶同工酶(CK-MB)峰值、肌钙蛋白T(TnT)峰值及心电图(ECG)的相关性.方法 对19例首次发病3～7 d的急件心肌梗死患者行心脏MR检查.采用1.5 T MR仪行首过灌注成像及延迟强化成像.分别评价每例患者的梗死质量、梗死百分比、左心室功能,记录TnT峰值、CK-MB峰值并分析ECG.对正态分布资料行Pearson相关性检验,对非正态分布资料行Spearman相关性检验.用独立样本t检验进行2组计量资料的均数比较.结果 19例患者的梗死质量中位数为6,3 g,与左心室射血分数(LVEF)(54.1±15.4)/呈负相关(r=-0.563,P=0.012),与TnT峰值(中位数为0.8μg/L,r=0.487,P=0.0340)、左心室收缩末期容积指数(LVESVI;中位数为23.4 ml/m2,r=0.480,P=0.038)相关.梗死百分比(中位数为6.0/)分别与TnT峰值(r=0.583,P=0.009)、CK-MB峰值(中位数为43.0 U/L,r=0.470,P=0.042)、每搏输出量[LVSV;(57.6±15.0)ml,(r=-0.482,P:0.036)]相关.TnT峰值还与LVSV相关(r=-0.524,P=0.021).心肌梗死ST段抬高与非ST段抬高相比,受累段数(中位数分别为3.0和2.0,t:2.972,P=0.009)更多,TnT峰值(中位数分别为1.0和0.7μg/L,t=2.245,P=0.041)、CK-MB峰值(中位数分别为43和35 U/L,t=2.508,P=0.024)更高.结论 急性期心肌梗死的梗死质最直接影响左心室功能.TnT峰值是反映梗死三百分比及左心室功能的较好指标,ST段抬高心肌梗死的范围更大.     

Eruption times of permanent teeth in teenage boys and girls in Izmir (Turkey)

In a study in the Aegean city of Izmir, Turkey, during the summer of 2002, 2101 patients (1046 boys and 1055 girls) were examined. The examination occurred within the framework of a dental check-up performed at two schools and one pre-school unit. The age span ranged from 3.98 to 24.91 years. Sex, age and present permanent teeth were recorded. Wisdom teeth were excluded. The sequence of tooth eruptions differs significantly in the lower and upper jaw, whereas no significant differences existed when comparing the sides of each jaw. The times of tooth eruption is earlier in females than in males. The entire tooth eruption process of the second dentition occurs in females earlier than in males. The tooth eruption in the lower and upper jaw of male and female probands is symmetrical. In comparing the upper and the lower jaw of both genders, it becomes evident that there is a tendency for earlier tooth eruptions in the lower jaw. In respect to the tooth eruption sequence, a change was noted in the upper jaw. Contrary to the reports of other authors, the second premolar has changed places with the canine and erupts prior to this tooth. Otherwise no major differences concerning the sequence of tooth eruptions, when compared to the results gained from other populations, were observed. Concerning the entire dentition, no acceleration of the tooth eruption could be noted. The computed differences of teeth eruption as a mean value calculated over all teeth, was +/- 1 year at maximum, compared to studies from different continents. Oral examination of teeth is a simple tool to calculate tooth eruption intervals. This first investigation on a population of Izmir revealed a change in the eruption sequence of permanent teeth. These findings are relevant for dental treatment planning and forensic odontology and should be reconfirmed at certain intervals.     

Determination of the optimal minimum radioiodine dose in patients with Graves' disease: a clinical outcome study.

The study was performed under the auspices of the International Atomic Energy Commission, Vienna, Austria, with the aim of determining the optimal minimum therapeutic dose of iodine-131 for Graves' disease. The study was designed as a single-blinded randomised prospective outcome trial. Fifty-eight patients were enrolled, consisting of 50 females and 8 males aged from 17 to 75 years. Each patient was investigated by clinical assessment, biochemical and immunological assessment, thyroid ultrasound, technetium-99m thyroid scintigraphy and 24-h thyroid 131I uptake. Patients were then randomised into two treatment groups, one receiving 60 Gy and the other receiving 90 Gy thyroid tissue absorbed dose of radioiodine. The end-point markers were clinical and biochemical response to treatment. The median follow-up period was 37.5 months (range, 24-48 months). Among the 57 patients who completed final follow-up, a euthyroid state was achieved in 26 patients (46%), 27 patients (47%) were rendered hypothyroid and four patients (7%) remained hyperthyroid. Thirty-four patients (60%) remained hyperthyroid at 6 months after the initial radioiodine dose (median dose 126 MBq), and a total of 21 patients required additional radioiodine therapy (median total dose 640 MBq; range 370-1,485 MBq). At 6-month follow-up, of the 29 patients who received a thyroid tissue dose of 90 Gy, 17 (59%) remained hyperthyroid. By comparison, of the 28 patients who received a thyroid tissue dose of 60 Gy, 17 (61%) remained hyperthyroid. No significant difference in treatment response was found (P=0.881). At 6 months, five patients in the 90-Gy group were hypothyroid, compared to two patients in the 60-Gy group (P=0.246). Overall at 6 months, non-responders to low-dose therapy had a significantly larger thyroid gland mass (respective means: 35.9 ml vs 21.9 ml) and significantly higher levels of serum thyroglobulin (respective means: 597.6 microg/l vs 96.9 microg/l). Where low-dose radioiodine treatment of Graves' disease is considered, a dose of 60 Gy will yield a 39% response rate at 6 months while minimising early hypothyroidism. No significant advantage in response rate is gained by using a dose of 90 Gy. For more rapid therapeutic effect at the expense of an increased rate of hypothyroidism, doses in excess of 120 Gy may be required. Ultrasound determination of thyroid mass and measurement of serum thyroglobulin levels may be predictive of those patients who will be less responsive to low-dose therapy.     

Measurements of tooth length in panoramic radiographs. 1. The use of indicators.

The aim of this study was to investigate both the actual and the radiographic tooth lengths of the maxillary first molar and second premolar and the mandibular premolars in panoramic radiographs. The actual length of 64 extracted teeth was measured. Steel balls were then attached to the cusp and apex and the teeth embedded in plastic moulds. Each pair of plaster casts with their set of teeth was radiographed with an Orthopantomograph twice at an interval of 1 month. The actual and the radiographic tooth length was measured twice by one observer. The mean tooth length of the molar was shorter than that of the premolars. The mean difference between the repeated measurements of the actual tooth length was small and ranged between 0.47 and 1.16% of the tooth length. The mean difference between repeated measurements of the radiographic tooth length was also small, with a method error of 0.13-0.21 mm. The vertical magnification in panoramic radiography was lower for mandibular premolars (13-15%) than for the maxillary second premolar and first molar (17-28%). The palatal root of the maxillary first molar had the highest vertical magnification (28%). Following the second set of radiographs, the mean difference between the measurements was small, except for the palatal root of the maxillary first molar (P < 0.001). Radiographic measurements of this root should therefore be used with caution. The results for the other roots examined indicate that these could be measured with high reproducibility.     

Apparent transverse relaxation rate in human brain varies linearly with tissue iron concentration at 4.7 T.

Multiple pairs of adiabatic passage pulses were implemented in a spin-echo sequence to achieve accurate measurements of the apparent transverse relaxation time (T(2)(dagger)) in a short scan time. In experiments on agarose gel phantoms with T(2) values ranging from 30 to 105 ms, the measured T(2)(dagger) values were in good agreement with transverse relaxation times measured with a nonselective Carr-Purcell-Meiboom-Gill sequence. In experiments on normal human brain at 4.7 T, T(2) (dagger) values in five different gray matter regions were found to range from 38 +/- 2 ms (globus pallidus) to 64 +/- 2 ms (frontal cortex). The apparent relaxation rate (1/T(2)(dagger)) in these five regions showed strong correlation (r = 0.97) with published levels of iron (Fe) in those regions. The linear coefficient relating 1/T(2)(dagger) and [Fe] at 4.7 T was measured to be 0.551 (s x mg Fe/100 g f.w.)(-1). When compared with the values obtained in a previous report for six different static fields (B(0)) up to 1.5 T, the current measurement confirms the linear dependence of the linear coefficient on B(0) up to 4.7 T (r = 0.99). These results suggest that the T(2)(dagger) value in the human brain is predominantly affected by the nonhemin iron distribution. The strong correlation between the obtained T(2)(dagger) values and the regional iron concentrations suggests a role for this pulse sequence in quantifying in vivo brain iron at high magnetic field.     

Direct determination of uranium and co-extracted elements in the organic phases (D2EHPA/TOPO, TBP, TDA) in kerosene by TXRF technique.

The total reflection X-ray fluorescence (TXRF) spectrometry was used for direct determination of uranium concentration in the organic phase di-(2-ethyl hexyl) phosphoric acid and trioctyl phosphine oxide (D(2)EHPA-TOPO)/kerosene, which resulted from first and second cycles of uranium extraction from wet-process phosphoric acid. The TXRF measurements were performed using gallium as an internal standard. A linear relationship between relative intensity of uranium vs. gallium (I(U)/S(Ga)) against uranium concentration has been obtained. Four calibration curves, 0-5, 5-100, 100-1000 and 1000-7000 microgmL(-1), according to uranium concentration in the studied samples, were constructed. The detection limit was found to be 0.15 microgmL(-1). The effect of D(2)EHPA and TOPO concentration in kerosene on uranium determination was considered. The TXRF spectrometry was also applied for the multi-elemental analysis of the co-extracted impurities with uranium, such as (Fe, Ni, Cu and Zn) in the organic phase, and four calibration curves, 0-500 microgmL(-1) Fe, 0-20 microgmL(-1) Ni, 0-10 microgmL(-1) Cu and 0-20 microgmL(-1) Zn, according to Fe, Ni, Cu and Zn concentration in the studied samples were performed, respectively, using gallium as an internal standard. The obtained results using direct TXRF analysis method were in a very good agreement with those obtained by fluorometry method, which is suitable for aqueous solutions after stripping of uranium from the organic phase by 1M Na(2)CO(3).