共查询到20条相似文献,搜索用时 15 毫秒
1.
AE Gómez-Ayala MS Campos I López-Aliaga I Pallarés S Hartiti M Barrionuevo MJ Alférez MC Rodríguez-Matas F Lisbona 《Canadian Metallurgical Quarterly》1997,67(2):106-114
The purpose of this study was to undertake a critical review of the potential role of magnetic resonance imaging (MRI) in the evaluation of low back pain (LBP) and to determine if there were differences in the MRI appearances between various occupational groups. The study group, 149 working men (78 aged 20-30 years and 71 aged 31-58 years) from five different occupations (car production workers, ambulance men, office staff, hospital porters and brewery draymen), underwent MRI of the lumbar spine. Thirty-four percent of the subjects had never experienced LBP. Twelve months later, the examination was repeated on 89 men. Age-related differences were seen in the MRI appearances of the lumbar spine. Disc degeneration was most common at L5/S1 and was significantly more prevalent (P < 0.01) in the older age group (52%) than in the younger age group (27%). Although LBP was more prevalent in the older subjects there was no relationship between LBP and disc degeneration. No differences in the MRI appearance of the lumbar spine were observed between the five occupational groups. Overall, 45% had 'abnormal' lumbar spines (evidence of disc degeneration, disc bulging or protrusion, facet hypertrophy, or nerve root compression). There was not a clear relationship between the MRI appearance of the lumbar spine and LBP. Thirty-two percent of asymptomatic subjects had 'abnormal' lumbar spines and 47% of all the subjects who had experienced LBP had 'normal' lumbar spines. During the 12-month follow-up period, 13 subjects experienced LBP for the first time. However, there was no change in the MRI appearances of their lumbar spines that could account for the onset of LBP. Although MRI is an excellent technique for evaluating the lumbar spine, this study shows that it does not provide a suitable pre-employment screening technique capable of identifying those at risk of LBP. 相似文献
2.
采用盐酸溶解样品,选择Co 240.72nm、Cu 324.75nm、Zn 213.86nm、Fe 248.33nm、Ca 422.67nm、Mg 202.58nm作为分析谱线,钴、铜、锌、铁选择3个像素点,钙、镁选择9个像素点,建立了连续光源原子吸收光谱法(CS-AAS)同时测定氧化镍中的钴、铜、锌、铁、钙、镁的方法。实验表明:在100mL测定液中加入2mL 200g/L氯化锶溶液,可消除测定介质(体积分数为2%的盐酸)对待测元素的影响;基体镍对测定的干扰可忽略。在优化的实验条件下,钴、铜、锌、铁、钙、镁的校准曲线相关系数均不低于0.999 0,且其方法检出限在0.002~0.092μg/mL之间。按照实验方法对氧化镍样品中钴、铜、锌、铁、钙、镁分别平行测定11次,钙和镁的测定值在0.1%~0.4%之间,其对应的相对标准偏差(RSD)不大于2%;钴、铜、锌、铁的测定值在0.003%~0.04%之间,其对应的相对标准偏差均小于10%。将实验方法应用于电真空镍光谱标准样品(该标样为氧化镍状态)中上述各元素的测定,结果与认定值基本一致。 相似文献
3.
To clarify the changes of mineral levels in different tissues of riboflavin-deficient rats, Wistar rats were separated into three groups. One group was fed a diet ad libitum that was deficient in riboflavin. The other two were fed either the complete diet that was weight-matched to the riboflavin-deficient group or fed a complete diet ad libitum. In riboflavin-deficient rats, the hemoglobin concentration and riboflavin contents of blood, liver, and kidney were significantly decreased, compared with weight-matched and ad libitum-fed controls. The mineral concentrations of tissues are summarized as follows: The iron (Fe) concentration in the heart, liver, and spleen was decreased in the riboflavin-deficient group compared with the other groups. Calcium (Ca) and magnesium (Mg) concentrations in tibia were decreased in the riboflavin-deficient group compared with the other two groups. Copper (Cu) concentration was increased in the heart and liver, when the riboflavin-deficient group was compared with the other groups. Zinc (Zn) concentration was increased in tibia when the riboflavin-deficient group was compared with the other groups. 相似文献
4.
The purpose of this study was: 1) to establish the prevalence of depleted iron stores, iron deficiency, and low serum levels for copper, zinc, calcium, and magnesium in a healthy female population; and 2) to examine the effects of iron supplementation and discontinuation on the serum levels of the above minerals. One hundred eleven healthy women between the ages of 18 and 40 yr reported for fasted morning blood sampling for iron, copper, zinc, calcium, and magnesium status. Forty-five subjects were either iron-deficient as defined by a hemoglobin level below 120 g.l-1 (four subjects) or iron deplete as defined by a serum ferritin value below 20 micrograms.l-1 (43 subjects). Two subjects fit both criteria. This subgroup continued with the study and were prescribed a normal therapeutic iron dose (320 mg elemental iron per day, taken as two Slow-Fe tablets.d-1 for a period of 12 wk). The subjects then discontinued the iron supplementation for a further 12 wk. The response of the various blood minerals was monitored at 6-wk intervals. Twenty-five subjects completed the full 24-wk treatment. The main conclusions to be made from this study were that: 1) For this sample population of women, iron depletion was quite common (39%), although low hemoglobin values (< 120 g.l-1) were only seen in 3.6%. No subjects fell below the criteria for low serum copper levels (< 13.3 mumol.l-1) nor low serum magnesium levels (< 0.6 mmol.l-1). Seven subjects (6.5%) fell below the criteria for low serum zinc levels (< 11.5 mumol.l-1) while two subjects (1.8%) were below the criteria for low serum calcium levels (< 2.20 mmol.l-1). 2) Therapeutic oral iron supplementation was successful in raising mean serum ferritin values from 15.9 micrograms.l-1 to 36.5 micrograms.l-1 but was not associated with decrements in serum copper or calcium levels. 3) The treatment did not significantly effect serum zinc and magnesium levels during the supplementation period, but a downward trend continued through the discontinuation phase so that at 18 and 24 wk serum zinc and magnesium levels were significantly lower than baseline. 4) Oral contraceptive use was associated with elevated serum copper and ferritin values and lowered serum magnesium levels. 相似文献
5.
This study is an investigation of the extraction of copper and zinc from a mixed sulphide concentrate by means of a conventional hydrometallurgical process, which was carried out in four stages: (a) catalytic sulphation roasting, (2) water leaching of the metallic values, (3) solvent extraction, and (4) selective stripping.More particularly, this investigation determined: (a) the roasting conditions favorable for the formation of the maximum amount of soluble copper and zinc sulphates; (b) the solvent extraction of iron and zinc from the leach solutions, applying the organic reagent D2EHPA diluted by cyclohexane or kerosene as a solvent; (c) the optimum conditions of selective stripping offering the ability to separate iron and zinc; and (d) the enrichment abilities of the electrolytes suitable for the electrowinning of the metals. 相似文献
6.
采用HF-HNO3-HClO4混酸消化样品,HNO3溶解盐类,火焰原子吸收光谱法直接测定试液中钙、铜、铁、锰的含量。对共存离子的干扰情况进行了考察,发现大量的Si对测定有干扰,在处理样品时通过生成SiF4除去;磷、铝、钛等元素对钙的化学干扰,通过加入释放剂SrCl2消除。背景吸收使用氘灯扣除。采用标准曲线法测定,Ca、Cu、Fe、Mn的校准曲线的线性范围分别为0.00~20.00μg/mL、0.00~6.00μg/mL、0.00~10.00μg/mL、0.00~6.00μg/mL,检出限分别为0.000 3μg/mL、0.001 3μg/mL、0.002 6μg/mL、0.006 9μg/mL。方法用于云冈石窟风化岩石中钙、铜、铁、锰的测定,相对标准偏差分别为2.8%、3.0%、1.4%、2.9%,加标回收率在96%~110%之间。 相似文献
7.
用火焰原子吸收光谱(FAAS)法直接测定高纯黄磷消解液中痕量Fe和Zn,结果发现抑制作用很强。磷酸三丁酯(TBP)作为萃取剂可将高纯黄磷消解液中的磷酸萃取分离,从而降低磷酸与Fe、Zn的络合作用同时降低磷酸的黏度,减少了用FAAS测定高纯黄磷中痕量Fe与Zn的抑制作用。试验优化后的萃取条件为:样品和TBP的体积比为1∶1,振荡1 min,静置30 min。此方法测定高纯黄磷中Fe和Zn的检出限分别为0.02 mg/L和0.01 mg/L,加标回收率均在90%~110%之间。 相似文献
8.
9.
Changes in the levels of lipid peroxides, natural antioxidants (NA), iron, zinc and copper as well as the ability of the lipid substrate to oxidize in animal liver in the presence of iron, zinc and copper have been studied. It has been found that those metals increase the amplitude of natural fluctuations in iron, zinc and copper levels in the liver (by 5-30% in comparison with control). Within the first few hours following administration of iron and copper, the concentration of lipid peroxidation (LPO) products in animal livers increases, while the NA level and lipid oxidizeability decrease, in contrast. Zinc inhibits LPO in the liver within the first few hours following the injection. The changes in the content of NA, lipid oxidizeability and the level of LPO products in animal livers following iron, zinc and copper administration are phase-dependent. Data from regression analysis indicate a direct dependence (kcor = 0.98 at p < or = 0.05) between lipid oxidizeability and NA content in the liver following administration of iron, zinc and copper which, in turn, is suggestive of the lack of disturbances in the system of NA regulation 相似文献
10.
I Kolokouris VP Kotsaki-Kovatsi N Economides A Poulopoulos G Rozos I Vlemmas 《Canadian Metallurgical Quarterly》1998,14(5):210-213
A zinc oxide and eugenol root canal sealer (Roth 811) and sterile saline solution were injected into the dorsal thoracic midline of 70 male Wistar-Furth rats. Every day for the next 7 days, 10 animals were sacrificed by either inhalation. The liver, heart, kidneys and brain were removed from the animals and analysed for zinc, calcium and copper concentrations by flame atomic absorption spectrophotometry. The tissue around the injection site was also surgically removed and prepared for histological evaluation under a microscope. The injection of Roth 811 significantly affected the concentrations of zinc, calcium and copper in some of the examined organs, especially on the 4th and 5th day. The inflammatory reaction adjacent to the material was severe during the first 3 days while on the 7th day the presence of connective tissue with collagen formation was observed. 相似文献
11.
We hypothesized that the competition between zinc (Zn) and copper (Cu) during fetal accretion of copper could be discriminated at either the dam-to-placenta or placenta-to-fetus stage. This premise was tested by feeding dams a high Zn diet (1000 mg/kg, HZn) during the second half of gestation. One day before delivery, dams were anesthetized, fetuses removed and both maternal and fetal tissues and plasma obtained and assayed. Other rats were fed a normal Zn concentration diet (32.4 mg/kg, ND) throughout pregnancy. There were significantly lower fetal liver Cu concentrations and greater plasma Fe concentrations, but not plasma Cu concentrations or liver Fe concentrations in the HZn group. Both dam and fetal Zn liver concentrations were greater in the HZn than in the ND group. Plasma Cu levels were lower in the HZn-fed than in the ND-fed dams. Placental tissue from the HZn litters had a greater concentration of Zn and Fe than did the ND group, whereas no effect was noted for Cu concentration. Metallothionein (MT) levels were elevated in dam livers and placenta in the HZn group, but there were no differences in fetal liver MT. The dynamic assessment of placental transport was conducted by injecting 2.5 mg/kg Cu acetate intravenously into dams of both groups. Sequential samplings of dam and fetal blood and placentas were taken from 0 to 60 min. After the Cu bolus, there was a consistently higher plasma Cu concentration in the HZn than in the ND dams, but no alteration in the concentration of Cu in the placenta or fetal plasma. This study indicates that placental Cu uptake is not affected by a high Zn diet in the dam. In addition, the greater Zn concentration in the placenta of HZn than in ND litters results in abnormal fetal Cu, Fe and Zn concentrations, suggesting that an imbalanced maternal mineral consumption is deleterious to normal divalent metal accretion. 相似文献
12.
BACKGROUND: Research investigating the relationship between physical training and trace mineral concentrations has primarily focused on athletes. Few investigations, however, have specifically examined the alterations of trace mineral concentrations occurring in humans exposed to +Gz acceleration. Exercise alters mineral content; G-exposure is a form of exercise; therefore, G-exposure may elicit changes in mineral content. HYPOTHESIS: Exposure to +Gz acceleration may affect the concentrations of the trace minerals zinc, copper, and chromium in human serum and urine. METHODS: Blood samples were obtained from 7 men and 3 women, before and immediately after +Gz acceleration. Urine samples were obtained before, 30 min after, and 2 h after +Gz acceleration. RESULTS: The serum zinc concentration was significantly different after +Gz acceleration, decreasing from 90.6 +/- 21.0 micrograms.dl-1 to 80.8 +/- 14.4 micrograms.dl-1. The serum copper concentration was also significantly altered immediately after +Gz acceleration, decreasing from 111.7 +/- 27.5 micrograms.dl-1 to 98.5 +/- 35.2 micrograms.dl-1. The urinary zinc and copper concentrations, and the serum chromium concentration were not significantly affected by +Gz acceleration. CONCLUSIONS: The circulating levels of these minerals presumably change as they are transported to the tissues requiring greater amounts due to the increased physiological work associated with +Gz acceleration. 相似文献
13.
用碘-二甲苯溶液对汽油进行氧化处理,硝酸(1+9)萃取,以原子吸收光谱法测定汽油中铁、镍、铜。铁、镍、铜的测定波长分别为248.3nm,232.0nm,324.8nm;检出限分别为0.0005μg/mL,0.0004μg/mL,0.0001μg/mL;工作曲线的线性范围为0.002~40.00μg/mL,0.001~50.00μg/mL,0.001~6.00μg/mL。对氧化剂、萃取剂的浓度及用量进行了试验,选择了最佳萃取时间。汽油中对被测元素有干扰的元素均在允许量范围内。方法用于汽油样品的分析,铁、镍、 相似文献
14.
Sixteen Holstein bull calves were fed a high-concentrate ratio supplemented with zinc, copper, and manganese, alone or in combination, for 10 wk. After 6 days of preliminary feeding of chromic oxide, fecal grab-samples were collected for 6 days. Calves were slaughtered, and samples of the contents of the reticulo-rumen, omasum, abomasum, small intestine, cecum, and large intestine were analyzed for chromic oxide, copper, and manganese. Absorption along the gastrointestinal tract, measured by comparison of one segment with the previous segment, indicated net secretion of copper in the abomasum but net absorption from the rest of the tract. The exception was that net secretion into the reticulo-rumen was associated with low dietary copper. Net secretion of manganese was mainly in the small intestine and cecum in all treatments. A higher proportion of copper apparently was absorbed when this mineral was supplemented in the ration. However, absorption of manganese was decreased slightly when manganese was supplemented in the ration. Reabsorption of manganese in the large intestine was probably greater than that of copper. 相似文献
15.
Kinetics and deposit morphology of gold cemented on magnesium, aluminum, zinc, iron and copper from ammonium thiosulfate-ammonia solutions 总被引:5,自引:0,他引:5
M. Karavasteva 《Hydrometallurgy》2010,104(1):119-122
The kinetics of gold cementation by magnesium aluminum, zinc, iron and copper at equal conditions as well as the morphology of cementation products and the dissolution of cementing agents were investigated. Both the effect of cementing agents on gold cementation rate and the dissolution of metals decrease in order Cu > Zn > Mg > Fe > Al. High dissolution of magnesium, zinc, iron and copper per mol deposited gold was found. Zinc is the most efficient cementing agent. Magnesium and iron can be used in gold cementation practice but the extremely slow cementation rate prevents the practical application of aluminum.Significant differences in the morphology of gold deposits on magnesium, aluminum, zinc, iron and copper were found: thick deposit layers with small or large cracks were observed on magnesium or zinc; porous layers of fern leaf-shaped dendrites on copper; compact smooth deposit of fine crystallites on iron and small very rare formations of fine dendrites on aluminum. 相似文献
16.
Alaskan malamute chondrodysplasia IV. Concentrations of zinc, copper and iron in various tissues 总被引:1,自引:0,他引:1
Trace mineral concentrations in various tissues of the chondrodysplastic (dwarf) Alaskan Malamute are remarkably different as compared to normal. The zinc level in heart tissue was depressed in dwarf animals (26 weeks). Copper concentration in the liver is elevated two to four fold in 26 week old dwarf animals and iron levels are significantly elevated in kidney, liver and pancreas of these animals. These observations suggest that the dwarf Alaskan Malamutes suffer from a genetic defect in trace mineral metabolism. If this is the case, then many of the skeletal lesions reported for these animals may be attributed to disorders in either zinc or copper metabolism. 相似文献
17.
样品经HCl消解后,分别选择Mn 279.5 nm,Cu 324.8 nm,Zn 213.9 nm,K 766.5 nm谱线作为分析线,采用火焰原子吸收光谱法测定低碳钢中锰、铜、锌、钾。4种元素的质量浓度在一定范围内与吸光度呈良好的线性关系。方法检出限分别为0.009 5, 0.013 8, 0.002 9和0.003 3 mg/L。对低碳钢样品进行测定,相对标准偏差 (n=7) 均在1 %以下,加标回收率在95 %~104 % 之间。 相似文献
18.
原子吸收光谱法连续测定金精矿中的银铜铅锌 总被引:1,自引:0,他引:1
针对金精矿日常化验中银、铜、铅、锌需分别溶样测定,浪费人力、时间,采用火焰原子吸收法一次溶样连续测定样品中的银、铜、铅、锌。金精矿采用盐酸-硝酸-氢氟酸-高氯酸混酸完全消解,盐酸(1+9)溶液定容,原子吸收光谱法进行测定。该方法加入标准物质回收率为96.9%~107.7%,相对标准偏差RSD(n=7)为1.17%~7.07%,检出限分别为Cu 0.001 5μg/m L、Pb 0.029 9μg/m L、Zn 0.011 2μg/m L、Ag 0.001 9μg/m L。该方法对金精矿中银、铜、铅、锌的测定结果与国家标准方法测定值相符。 相似文献
19.
A group of patients with long-surviving mismatched kidney allografts were investigated for complement function using haemolytic assays in agarose gels. One patient was found to have no alternative pathway activity but a low normal classical pathway. Surprisingly, investigation revealed that the patient's complement was normal for all components except C9, which was functionally absent. The patient was shown to be heterozygous for DNA markers in the C6, C7 and C9 region of chromosome 5 and therefore appears to be a compound heterozygote for two uncharacterized C9 deficiency genes. Serological analysis by ELISA revealed that he has trace concentrations of a non-functional C9 molecule. Western blot analysis was not sufficiently sensitive to permit detection of this molecule. We hypothesize that the patient is heterozygous for a complete deficiency of C9 and for a gene directing hyposynthesis of a defective C9. We also suggest that C9 deficiency may be more common among Caucasians than has been reported. 相似文献
20.
采用微波消解技术对样品进行预处理,确定了试剂的配比、微波消解功率、时间、压力、冷却温度等关键因素,建立了微波消解-电感耦合等离子体原子发射光谱法测定铁精粉中K,Na,Pb,Zn的方法。确定了仪器的最佳工作条件,选择了合适的分析谱线,采用基体匹配法和适宜的操作参数消除基体干扰及抑制背景干扰。方法测定各元素的检出限在0.000 3%~0.001 8%之间,各元素回归曲线相关系数均在0.999 1~0.999 9之间。方法用于样品的测定,相对标准偏差为0.33%~2.05%,回收率为98.5%~104%。 相似文献