Effect of dietary calcium during pregnancy and lactation on zinc levels in blood and bone, in rats

The effect of dietary calcium (Ca) level on maternal zinc (Zn) nutritional status was studied. Female Wistar rats, weighing 250-350 g, were fed during pregnancy and lactation with an experimental diet containing/100 g different levels of calcium: 0.2 g (low calcium: LCa), 0.6 g (normal calcium: NCa) or 0.9 (high calcium: HCa). Maternal blood samples were drawn from the tail at delivery and at the end of lactation. Laboratory determinations were: Zn in whole blood (WB) at delivery and weaning; Zn (ZnF) and Ca (CaF) in the ashed femur at weaning. The results (mean +/- SEM) were: ZnWB (microgram/ml) at delivery and weaning: LCa: 8.73 +/- 1.05; 12.8 +/- 2.02; NCa: 3.49 +/- 0.19; 3.73 +/- 0.37; HCa: 3.21 +/- 0.19; 3.85 +/- 0.27. CaF (mg/100 mg): LCa: 19.2 +/- 0.8; NCa: 21.4 +/- 0.6; HCa: 20.4 +/- 1.1. ZnF (microgram/100 mg): LCa: 30.2 +/- 0.9; NCa: 24.1 +/- 0.3; HCa: 24.1 +/- 0.9. ZnWB was significantly higher in LCa (p < 0.0001) regarding NCa and Hca. ZnF showed an increase and CaF a decrease in LCa regarding NCa and HCa (p < 0.0001). There were no significant differences in ZnWB, ZnF and CaF between NCa and HCa These results show that: there was no detrimental effect when dietary Ca content was increased by 50% above the normal requirements of the rat.; low dietary Ca during pregnancy and lactation produced an increase of Zn utilization, reflected in maternal blood Zn and in ZnF content.     

机械镀锌过程中锌粉运动的模拟分析

基于离散单元法,采用EDEM离散元软件模拟机械镀锌过程,研究了冲击介质以不同速率冲击时锌粉的运动特性.结果表明,在机械镀锌过程中,锌粉先被纵向压缩,最后通过在纵、横方向进行重排和压缩变形得到镀锌层.上层锌粉主要发生变形和重排,中、下层锌粉以重排为主.当冲击速率为1.0 m/s时,所得机械镀锌层光滑平整,附着力为0级.模...     

Oxidative stability of low density lipoproteins and vitamin E levels increase in maternal blood during normal pregnancy

In 24 healthy pregnant women, parameters related to the oxidative stability of low density lipoproteins (LDL) were determined at three times during pregnancy and shortly after delivery. The fatty acid composition of plasma phospholipids (PL) and the plasma concentrations of vitamin E, vitamin A, and β-carotene were assessed in the same samples. Total triglyceride (TG), total cholesterol, LDL-cholesterol, and high density lipoprotein (HDL)-cholesterol concentrations were also determined. The length of the lag phase of isolated LDL challenged with Cu²⁺ ions significantly increased with the progression of pregnancy. The oxidation rate and the amount of conjugated dienes formed increased and reached a maximum at 29–37 wk of pregnancy. Total TG, cholesterol, and LDL-cholesterol reached a maximum in the third trimester of pregnancy. β-Carotene remained stable, vitamin A decreased, and vitamin E significantly increased throughout pregnancy. Vitamin E plasma concentration correlated positively with the length of the lag phase. The increased levels of vitamin E could contribute to the higher resistance of LDL toward oxidation with progressing gestation, measured by the prolonged lag phase. Furthermore, vitamin E plasma levels correlated positively with TG concentration but not with LDL-cholesterol. The level of polyunsaturated fatty acids in PL decreased with the progression of pregnancy. No correlation was found between the fatty acid composition of plasma PL, nor with the cholesterol concentration, and the parameters studied related to the oxidative stability of LDL. The major finding of this study is the increased oxidative resistance of LDL with progressing gestation.     

Increased docosahexaenoic acid levels in human newborn infants by administration of sardines and fish oil during pregnancy

In rhesus monkeys, maternal n-3 fatty acid deficiency during pregnancy produces infant monkeys deficient in n-3 fatty acids at birth. These results stimulated current experiments to find out if n-3 fatty acids from fish in the diets of pregnant women would influence the concentration of docosahexaenoic acid (DHA, 22:6 n-3) in the newborn human infant. Fifteen healthy pregnant women were enrolled to receive a 9-wk dietary supplementation of n-3 fatty acids from the 26th to the 35th wk of pregnancy. Sixteen pregnant women were not supplemented and served as controls. n-3 Fatty acid supplementation consisted of sardines and additional fish oil, which provided a total of 2.6 g of n-3 fatty acids per day (d) for the 9-wk period of supplementation. This included 1.01 g DHA. The end point of this study was the blood concentrations of DHA in the newborn infant. DHA in maternal red blood cells increased from 4.69% of total fatty acids to 7.15% at the end of the supplement period and at the time of delivery decreased (as expected) to 5.97% of total fatty acids. Maternal plasma showed a similar change from 2.12 to 3.51% of total fatty acids and then decreased to 2.35%. Levels of DHA in plasma and red blood cells of unsupplemented mothers did not change during the same time period. Levels of DHA in blood of newborn infants differed greatly in infants born from n-3-supplemented mothers compared with control infants. In red blood cells, DHA was 7.92% of total fatty acids compared with 5.86% (control infants). Plasma values showed a similar difference: 5.05% vs. 3.47% (controls). In n-3-supplemented infants, DHA concentrations were 35.2% higher than in control infants in red blood cells and 45.5% higher in plasma. These data indicate the importance of maternal dietary n-3 fatty acids and, in particular, maternal dietary DHA in promoting higher concentrations of DHA in the blood of the newborn infant.     

Prevalence of anemia during pregnancy: results of Valencia (Venezuela) anemia during pregnancy study

To determine the prevalence of anemia during pregnancy in Venezuelan pregnant women. By using a cross-sectional study, 630 Venezuelan pregnant women in their third trimester at labor from the Valencia Anemia during Pregnancy Study were studied. Anemia during pregnancy was defined according to WHO guidelines (Hb < 11 g/dl), iron deficiency was considered when serum ferritin level was < 12 ng/ml, and when serum folate level was < 3 ng/ml, it was considered as folate deficiency. 630 pregnant women (mean [+/- SD] age, 24 +/- 6.4 years) having an average of Hb 11.38 +/- 1.47 g/dl [95%CI = 11.27 to 11.50] were studied. No patient had hemolytic anemia nor clinical infections. Almost all patients were from low or very low socioeconomic status. Prevalence of anemia was 34.44% (severe: 1.8%, moderate: 15.2%, and mild: 83%). Iron deficiency anemia (IDA) was present in 39.2% (95%CI = 32.7 to 45.7), prevalence of folate deficiency anemia (FDA) was 11.98% (95%CI = 7.6% to 16.3%). Combined anemia (IDA and FDA) occurred in 11.52% (95%CI = 7.27% to 15.7%). Multivariate analysis showed that multiparous (odds ratio -OR-: 1.95, 95%CI = 1.28 to 2.97, p = .002) and supplement use of iron (OR: .55 (95%CI = .33 to .91, p = .02) are associated with IDA. The factors associated with FDA were: supplement use of folic acid (OR: .37 (95%CI = .19 to .71, p = .003) and appropriate prenatal control (OR: .51 95%CI = .27 to .96, p = .04). Prevalence of anemia during pregnancy was found to be high. Educational efforts should be stressed in order to encourage improvements in the prenatal care visits.     

Phase evolution during sintering of Bi-Ti-doped zinc oxide

Phase evolution and localization during sintering of spherical Bi-Ti-doped zinc oxide powders were studied by X-ray diffraction and transmission electron microscopy. Several minor phases were identified on quenched ceramics; a phase, either amorphous or crystalline, stable at a wide range of compositions, originating from solidification of the melt phase during quenching, was detected. Sintering processes were discussed: depending on the Ti content, densification, liquid-phase occurrence and grain growth are quite different.     

Effect of alimentation on human serum squalene levels

Five subjects consumed a meal containing ca. 1.5 mg squalene. Postprandial serum samples showed that in three of the subjects squalene and lipid levels reached maxima at 3 hr. Squalene levels in the low density lipoproteins of these subjects also increased. The results indicate that alimentation is a major factor in the variation in serum squalene levels.     

Impedance measurements during the cycling of a zinc electrode

Impedance spectra have been obtained during the cycling of a zinc electrode both in a Leclanché-cell-type electrolyte and in an alkaline zincate solution. Changes in impedance plots indicate an increase in the electrode area and a variation of the electrode kinetics with cycling. The kinetics of zinc deposition appear to be very sensitive to the contamination of electrolytes by dissolution products. The results confirm a correlation between the presence of an additive such as NBu₄ Br and the increase of the cycle life of the zinc electrode.     

Evaluation of levels and methods of zinc application to rice in sodic soils

Field experiments were conducted in zinc-deficient sodic soil to study the effect of levels and methods of zinc fertilization on yield, concentration and uptake of zinc by rice. Zinc was incorporated in the soil at the rate of 0, 5.6, 11.2 and 22.4 kg Zn per ha as zinc sulfate; sprayed on the plants at 1% and 2% zinc sulfate solution; and roots of rice seedlings were dipped in 2% and 4% ZnO suspensions in water. Grain yield, zinc content and its uptake increased in all the experiments up to 22.4 kg Zn per ha. Soil applied zinc was significantly correlated with yield of rice (r = 0.80^**) and zinc uptake (r = 0.89^**). Zinc content in 45-day old plants gave a significantly higher correlation with grain yield (r = 0.84^**) than the zinc content of rice straw and grain at maturity. Roots of rice seedlings dipped in 2% or 4% zinc oxide suspension in water were not only comparable with soil application of Zn at 5.6 and 11.2 kg Zn per ha, but also proved to be more economical for sodic soils showing moderate zinc deficiency.     

Behavior of the Ti-Al system during mechanical activation

Behavior of the Ti-Al system during its mechanical activation in a high-energy planetary mill was explored. Complete amorphization of Al was attained after τ = 25 min of mechanical activation. The kinetics of changes in crystallite size (L) and micro stress (σ) in Ti and Al was derived. For τ < 25 min, no formation of intermetallics was observed.     

Behavior of Silver and Palladium Mixtures during Heating

The behavior of mixtures of silver and palladium during heating in both air and an inert atmosphere was studied using X-ray diffractometry (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dilatometry, and scanning electron microscopy (SEM). In situ high-temperature XRD studies on a commercial 20% palladium material with submicrometer-sized particles indicated that an intermetallic phase, most likely Ag₃Pd, formed in air between 300° and 400°C, the same temperature range where a 13% linear expansion was measured by dilatometry. The DSC data indicated an exothermic peak at 340°C, a temperature where the TGA results indicated that the material had picked up only 0.2% oxygen, compared with the maximum of 1.4% at 525°C. No PdO was detected by XRD at 400°C, which suggests that oxygen was being incorporated in the intermetallic. Microstructural examination using SEM indicated that larger particles, with internal pores, had formed after heating in air to 375°C. When the material was heated in argon for 1 h at 400°C, no intermetallic phase or alloy formed, and minimal expansion occurred. When mixtures of larger silver particles (5–30 μm) with palladium particles (1–3 μm) were heated in air, the maximum amount of expansion that occurred increased from 0% for pure palladium up to a maximum of 18% at 75% silver. This result supports the conclusion that expansion is a result of formation of this new phase, in the presence of oxygen, not of the oxidation of the palladium.     

Behavior of mercury release during thermal decomposition of coals

The mercury release behavior during thermal decomposition of three Chinese coals with different types was studied under nitrogen, carbon dioxide and air at temperatures of 800, 900, 1,000 and 1,100 °C. The thermal treatment experiments were carried out in a quartz tube reactor. Results showed that the release ratio of total mercury during thermal decomposition of coals increases with the increasing temperature. The order of the amount of mercury released under the three atmospheres is nitrogen<carbon dioxide<air for all three coals during thermal decomposition. This indicates that air and carbon dioxide can promote the mercury release due to their reactivity with coal. However, the order of amount of elemental mercury released under the three atmospheres is nitrogen>carbon dioxide>air for all three coals. The release behavior of the total mercury under air is independent of the coal type. Under the other two atmospheres the release behavior is distinguished by the coal type. This work was presented at the 7 ^th China-Korea Workshop on Clean Energy Technology held at Taiyuan, Shanxi, China, June 26–28, 2008.     

Serum levels of zinc and copper and erythrocyte superoxide dismutase activity in alcoholic patients

Serum Zn and Cu levels were measured in 18 chronic alcoholic patients, without clinical signs of hepatic failure, and in 10 control subjects. Low serum Zn levels were observed in the alcoholics, probably due to the low protein ingestion of these individuals. Unlike the control group, no correlation was found between serum Zn and albumin levels in the experimental subjects. High levels of dietary Cu, mostly derived from wine, resulted in hypercupremia in the alcoholic patients. No significant changes in the erthrocyte activity of superoxide dismutase were observed.     

Behavior of the western pine beetle during host colonization

After living ponderosa pines were baited with either female-infested bolts or synthetic pheromones,Dendroctonus brevicomis were caught on sticky screens throughout trapping periods of 15–46 days; however, large numbers of beetles were trapped during only a small portion (5–10 days) of these trapping periods. The most attractive portions of trees attacked contained 3–6 beetles dm², in galleries ca. 2 cm long. Catch increased following addition of males to female-infested bolts, supporting the hypothesis that male-produced frontalin is an attractive pheromone of the western pine beetle. Catch at bolts removed from trees under attack was strongly dependent upon levels of boring activity. We found no evidence of interruption of the response to attractants during host colonization.Coleoptera: Scolytidae. Trade names and commercial enterprises or products are mentioned solely for information and do not constitute endorsement by the U.S. Department of Agriculture or University of California.     

流化床气化中小龙潭褐煤灰结渣行为

为探索小龙潭褐煤流化床气化过程中的煤灰结渣行为,采用化学成分、扫描电镜(SEM)和X射线衍射(XRD)相结合对小龙潭煤气化炉内残留渣块和不同温度热处理后煤灰的成分、形貌和晶相组成进行了表征和对比分析,并对升温过程中煤灰的矿物质演变进行了研究。结果表明:在小龙潭气化过程中流化床气化过程中渣块形成时铁元素发生了明显的富集,小龙潭气化残留渣块和950℃煤灰的微观形貌和晶相组成基本相同。小龙潭褐煤在流化床气化过程中950℃左右生成低熔点共融物钙长石、钙黄长石和铁钙辉石等是引起结渣的主要因素。     

The degradation of aluminium cathodes by fluoride ion during zinc electrowinning

The influence of fluoride ions on aluminium cathode surface degradation during zinc electrowinning has been studied. Electrolyte with a composition similar to that employed in plant operations has been used. A direct correlation is shown between the electrolyte fluoride content and the number of deposition cycles possible before zinc removal becomes difficult. The role of initial nucleation and starting electrode morphology is discussed in terms of the degree of adherence observed. Electrochemical tests have also been made on the electrodes at various stages of the process in an attempt to gain a better fundamental understanding of the mechanisms responsible for the adherence. The results indicate that the severity, of the adherence is generally determined by the amount of residual zinc remaining on the surface after stripping and the fluoride content of the solution during plating. The contribution of physical surface condition alone seems to be less significant than the chemical conditions imposed during deposition.     

聚氟乙烯薄膜成型过程中结晶行为研究

采用流延法制得的聚氟乙烯薄膜在不同的水浴温度下冷却,用X射线衍射法表征薄膜样品的结晶度并将薄膜样品在不同的温度下进行溶剂脱除实验,获得了溶剂脱除速率曲线.结果表明:水浴冷却温度越高则薄膜的初始结晶度越高;薄膜初始结晶度越低则溶剂脱除速率就越快;溶剂在脱除过程中,薄膜的结晶度会增加,结晶度的增加同时也会降低溶剂的脱除速率.     

聚丙烯拉伸断裂过程中的银纹性能研究

在18℃和26℃两种测试温度下,分别以0.1、0.5、1、5、20和50 mm/min的拉伸速率对无规共聚聚丙烯(PP-R)全切痕拉伸样条进行拉伸测试,以观察PP-R的银纹性能,并对PP-R全切痕拉伸过程中应力-位移曲线、位移-屈服应力曲线和拉伸断面进行了分析。结果表明:PP-R的屈服应力随着拉伸速率的增加而增大,并且随温度的上升而减小;在较低温度和较高拉伸速率时,PP-R的全切痕拉伸断裂可能是由常临界位移控制的银纹断裂;而在较高温时,PP-R的全切痕拉伸断裂过程几乎无常临界应力和常临界位移存在,说明PP-R拉伸断裂前几乎无沿拉伸方向的银纹微纤产生。     

Dihydropyridine derivatives as controllers for production of hydrogen during zinc dissolution

Two of dihydropyridine derivatives, namely, 4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (DPCN) and 4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carboxamide (DPCA) were evaluated as controllers for H₂ production during the dissolution of Zn in dilute HCl. Different chemical (thermometry, gravimetry, and gasometry) and electrochemical (potentiodynamic polarization and impedance) techniques were used. SEM and optical profilometry surface investigations for some corroded and un-corroded Zn samples were carried out to describe the Zn surface during the dissolution process. The rate of H₂ production was found to increase with the immersion time and temperature and was lowered by the inhibitor. The potentiodynamic data proved that DPCN and DPCA inhibit the dissolution of Zn according to a mixed-type mechanism.