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1.
To determine the association and its magnitude between prematurity and anemia in women in their third trimester of pregnancy and at labor. An incident case-control study was conducted using 2 controls per case. Data was obtained in a tertiary hospital in Valencia, Venezuela. A total of 543 women who delivered between May and December 1996 entered into the study. Women having a preterm delivery, less than 37 weeks of gestation at delivery, were defined as cases (n = 181). Anemia was defined according to WHO as Hb less than 11 g/dL. Logistic regression was used to analyze the data and likelihood ratio test was done for model comparison. Maternal anemia was found to be significantly associated with prematurity (Odds Ratio: 1.70; 95% CI = 1.18 to 2.57 P = .001), after adjusting for Placental Abruption, PROM, Previous Premature Labor, Prenatal Care Visits, and Uterine Bleeding during more than one trimester. Maternal anemia at the end of the third trimester of pregnancy, at labor, was associated with an increased risk of prematurity.  相似文献   

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Given the difficulties surrounding evaluating food consumption, specifically during adolescence, the goal of the present study was to compare different dietary assessment instruments used for this age group. The study was carried out with a group of 60 female adolescents between 14 and 18 years of age. Three repetitions of 24-Hour Recall, three-day Dietary Records and Purchase List of the adolescents and their families were collected. The 24 Hour Recall and Dietary Records had good repeatability, allowing to infer that only one application of one of these instruments was capable of reflecting the ingestion average (or median) of the study population group. The Purchase List allowed us to know the food availability within the context of the individual's conditions. All dietary assessment instruments may contain errors, therefore the choice of the most adequate method must rely on the objectives of the study being developed, as well as the study population.  相似文献   

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A sample of 215 adolescents (16.9 +/- 0.7 y; 13-18 y) from a low socioeconomic level of Valencia, Venezuela, at their first trimester of pregnancy were studied in order to identify nutritional risk. Socioeconomic, anthropometrical, hematological and dietary characteristic were assessed. Pregestational weight, actual weight, height, arm circumference (AC), triceps skin fold (TS), fat and muscle area (FA/MA) and pregestational body mass index (PBMI) were determined. Hemoglobin (Hb) and ferritin were measured by colorimetric and ELISA methods. Two 24 hour recalls were obtained. According to age, two groups were created. Pregnant adolescents were grouped by age: Group 1, 13 to 15 years old and Group 2, 16 to 18 years old. Nutritional risk was defined as: Gynecological age lower than 4 years since menarche. PBMI < 19.8 kg/m2, height below 10th Percentile of reference, Hb below 11 g/dL and ferritin < 12 micrograms/L. Almost all the adolescents (96.3%) were in poverty. 83.3% were single, 83.3% were at elementary school before pregnancy but 84.1% were attending house chores at the time of exam. There were significant differences (p < 0.001) for gynecological age and menarche age, but not for anthropometrical, hematological and dietary variables when Group 1 was compared to group 2. 35.3% of the adolescents had a gynecological age lower than 4 years, 23.3% were below 10th percentile for height, 36.3% had a PBMI lower than 19.8 kg/m2, 26.5% were below 10th percentile for arm circumference, anemia was present in 13.7% and low levels of ferritin in 18.4% of the adolescents. Calorie intake was below recommendation in 87.3% and adequacy for vitamin A and C, calcium and zinc were below 2/3 of recommendation in 36.3%. 25.9%, 88.7% and 73.5% of the adolescents respectively. Studied adolescents had a high prevalence of risk factors for nutritional deficiencies (short age, poverty, low weight, anemia and deficient intake). Early assessment of this conditions allows to identify the risk, to establish interventions and to monitor pregnancy evolution.  相似文献   

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One hundred female adolescents (13-18 y) were clinical and anthropometrically studied to select only those with adequate nutrition. Most adolescents belonged to IV socio-economic stratum families (worker class). Height, weight, age, body mass index and medial arm circumference were used as anthropometric parameters. After screening, only 41 non pregnant girls (control) and 42 pregnant girls with adequate nutrition were selected to analyze plasma amino acids. Fasting peripheral venous blood was drawn, and plasma amino acids were analyzed by HPLC. Amino acid concentrations were expressed as umol/L +/- SE. SAS/STAT program was used for statistical analysis. Amino acid values of control adolescent group were found in ranges reported by other investigators, with slight variations, mostly in diminution, presumably due to nutritional, metabolic or genetic conditions of people living in tropical regions. In pregnant healthy adolescents, distributed according to gestational age: < 32 weeks (n = 30) and > 32 weeks (n = 12), a diminution of total molar plasma amino acids was found, by comparing with control values. Ten amino acids (Pro, Gly, Gln, Arg, Ser, Orn, Tau, Leu, Thr and Val) appeared significantively diminished throughout gestation, being Gly. Gln and Arg most affected since earlier weeks. During the 2nd period. Thr and Val increased their grade of affectation; whereas some amino acids values (Orn, Pro and Tau) tended to recuperate. Several of affected amino acids are gluconegoenic, thus, they could be utilized to supply the energy required by the pregnant adolescent against her double stress: the fetus development and her own development. The plasma amino acid values reported in both, healthy non pregnant and pregnant adolescents, could be taken as regional referential profile of plasma amino acids in this poblational group for further research on adolescent and fetal--maternal malnutrition.  相似文献   

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The two particular exponential integrals involved in the conventional solutions for ideal adiabatic tubular reactors are represented by a modified series for computation purposes. For arguments larger than ten in absolute value, the method of asymptotic expansion removes the inconveniences that may be encountered in the numerical evaluation of the solutions. The expressions obtained with the modified series are not restricted by zero heat of reaction as is the case with the conventional solutions. General solutions, easily amenable to computer evaluation, are presented for first and second order irreversible reactions, under adiabatic or isothermal conditions.  相似文献   

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Sugarcane bagasse and trash are used as fuels in cogeneration systems for bioethanol production, supplying steam and electricity, but may also be used as feedstock for second generation ethanol. The amount of surplus lignocellulosic material used as feedstock depends on the energy consumption of the production process; residues of the pretreatment and hydrolysis operations (residual cellulose, lignin and eventually biogas from pentoses biodigestion) may be used as fuels and increase the amount of lignocellulosic material available as feedstock in hydrolysis. The configuration of the cogeneration system (boiler pressure, lignocellulosic material consumption and steam production, turbines efficiencies, among others) has a significant impact on consumption of fuel and electricity output; in the integrated first and second generation, it also affects overall ethanol production. Simulations of the integrated first and second generation ethanol production processes were carried out using Aspen Plus, comparing different configurations of the cogeneration systems and pentoses use (biodigestion and fermentation). Economic analysis shows that electricity sale can benefit second generation ethanol, even in relatively small amounts. Environmental analysis shows that the integrated first and second generation process has higher environmental impacts in most of the categories evaluated than first generation.  相似文献   

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在岩心观察的基础上,从单井沉积相的分析入手,并结合钻井岩性剖面、沉积构造和电性特征等大量地质资料,详细分析了吐哈油田2、3井区三叠系的沉积相类型、特征及其展布;认为该区发育一套湖进式扇三角洲沉积体系。扇三角洲层序完整,扇三角洲平原亚相,主要包括辫状分支河道,河道侧缘和分支间湾微相;扇三角洲前缘亚相,主要包括水下分支河道、河道侧缘边滩及分支河道间湾三个微相;前扇三角洲亚相主要由深灰色泥岩构成。  相似文献   

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We designed and synthesized two novel series of azapodophyllotoxin analogues as potential antivascular agents. A linker was inserted between the trimethoxyphenyl ring E and the tetracyclic ABCD moiety of the 4-aza-1,2-didehydropodophyllotoxins. In the first series, the linker enables free rotation between the two moieties; in the second series, conformational restriction of the E nucleus was considered. We have identified several new compounds with inhibitory activity toward tubulin polymerization similar to that of CA-4 and colchicine, while displaying low cytotoxic activity against normal and/or cancer cells. An aminologue and a methylenic analogue were shown to disrupt endothelial cell cords on Matrigel at subtoxic concentrations, and an original assay of drug washout allowed us to demonstrate the rapid reversibility of this effect. These two new analogues are promising leads for the development of vascular-disrupting agents in the podophyllotoxin series.  相似文献   

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The purpose of this study was to analyze the diagnostic capacity of different classification criteria based on Body Mass Index in the assessment of nutritional status and to evaluate their effectiveness. The sample comprised 367 healthy pregnant adolescents in their first trimester of gestation, from a socioeconomic level IV, between Oct. 1999 and Dec. 2008. Two methodologies were applied for the nutritional classification: (1) Integral nutritional diagnosis (gold standard), and (2) Body Mass Index (BMI), using local reference values: Proyecto Venezuela and the Transversal Study of Caracas, and international reference values: Frisancho and WHO 2006. Concordances, kappa, sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios, and the Youden index were calculated. According to the gold standard and BMI, the percentage of well-nourished pregnant women ranged between 62.4% and 80.6%. Within the deficit range, Frisancho was the most effective with kappa: 0.80; sensitivity: 87.3%; specificity: 94.8%; positive likelihood ratio: 16.9, and negative likelihood ratio: 0.13; Youden index: 0.82. Within the excess range, Frisancho and the Transversal Study of Caracas were the most effective with Youden index: 0.86 and 0.83, respectively. These results revealed that Frisancho was the best criterion to diagnose malnutrition in deficit in pregnant women. All references have an adequate diagnostic capacity for the excess range, of which Frisancho and the Transversal Study of Caracas are the best. We recommend using such reference values to optimize the efficiency of the BMI indicator in diagnosing malnutrition in deficit and in excess in the first trimester of gestation in pregnant adolescents within populations with similar characteristics.  相似文献   

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Summary (11'-Chlorodimethylsilylundecyl)-2-chloro-2-phenylacetate 2 as an atom transfer radical polymerisation (ATRP) initiator was bound covalently to the surface of silica. ATRP grafting of styrene monomer from the silica surface was achieved and the grafts were detached from the solid particles for analysis. It is shown that after polymerisation of a first generation of grafts and work-up of the thus grafted silica the chain ends of the grafts are still active to initiate a second monomer feed to further chain growth. Received: 17 July 1999/Revised version: 12 December 1999/Accepted: 10 January 2000  相似文献   

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Summary The steady state radial pressure distribution in the truncated cone-and-plate (TCP) apparatus has been measured for a highly elastic polyisobutylene solution in cis-trans decalin (MW=4300 kgmol–1 MW/Mn=2) at eight shear rates from 1 to 270 s–1 and temperatures of 3.0, 20.0, 30.0 and 46.0° C. The slope of pressure, corrected for inertia by the classical formula, versus the logarithm of radius provides a combination of normal stress differences N1+2N2 with a typical experimental scatter of 1 % at all measured temperatures and shear rates. The plots of N1+2N2 versus shear rate can be shifted, without loss of accuracy, by means of the time-temperature superposition principle, the shift factors strictly adhering to a WLF equation. Extrapolated rim pressures, when corrected for elastic hole pressure with a theoretical equation, give values of the second normal stress difference with typically less than 10 % of experimental scatter. Contrary to previous analyses of the TCP apparatus, the center-hole pressure is found to give a useful estimate of the second normal stress difference, although there are insufficient data at present to perform the differentiation of a nonlinear function required in the analysis of the data. Instrument imperfections are reviewed briefly in the Appendix.  相似文献   

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邓文 《中国橡胶》2010,26(15):8-11
<正>一、上半年橡胶行业经济运行简况今年以来,橡胶行业经济形势继续向好回升,但增幅收窄。据对10个分会309家重点会员企业统  相似文献   

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The distribution of phospholipids as well as their fatty acid compositions of rat mammary tissues were examined during pregnant, lactating, and post-weaning periods. There was no apparent change in phospholipids and their acyl groups during the early and late pregnant periods. However, tissue phospholipid composition was different during pregnant, early, and late lactating periods. After parturition, there was a marked increase in the proportion of diacyl-glycerophosphorylcholine in the phospholipids of mammary tissue, but this proportion decreased gradually during lactation. The decrease in diacyl-glycerophosphorylcholine during lactation was marked by a corresponding increase in diacyl-glycerophosphorylethanolamine. Although the shorter chain fatty acids of triglycerides were increased during lactation, only a small proportion of these fatty acids was found in the phosphoglycerides. Marked changes in acyl group composition of individual phospholipids are found during these different physiological stages. In general, there was a rapid decrease in 20∶4 and an increase in 18∶2 in the major phosphoglycerides during parturition. The proportion of 20∶4 in the phosphoglycerides remained low throughout the entire lactating period, while that of 18∶2 continued to increase 2–3 fold. Most of the changes in acyl group of the phosphoglycerides during lactation returned to normal ca. 10 days after weaning. A possible relationship of the variation of phospholipid and acyl group compositions in mammary tissue to changes in hormonal pattern during different physiological stages is discussed.  相似文献   

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Climate change mitigation has become a binding driver in biofuels production. First generation bioethanol, initially indicated as the most competitive option, is now incurring in ever increasing discredits forcing the transition towards more sustainable productions (i.e. second and third generation technologies). This paper addresses the strategic design and planning of corn grain- and stover-based bioethanol supply chains through first and second generation technologies. A Mixed Integer Linear Programming framework is proposed to optimise the environmental and financial performances simultaneously. Multi-period, multi-echelon and spatially explicit features are embodied within the formulation to steer decisions and investments through a global approach. A demonstrative case study is proposed involving the future Italian biomass-based ethanol production. Results show the effectiveness of the optimisation tool at providing decision makers with a quantitative analysis assessing the economic and environmental performance of different design configuration and their effect in terms of technologies, plant sizes and location, and raw materials.  相似文献   

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