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ABSTRACT: Simple and effective protocols for bonding Cu-based high-aspect-ratio microscale structures (HARMSs) are essential for assembly
of Cu-based microdevices. In this paper, Cu-to-Cu bonding with thin intermediate layers of elemental Sn is explored. Bonding
quality is assessed through quantitative evaluation of tensile bond strength as a function of bonding parameters such as temperature
and applied pressure. Structural examination of the Cu/Sn/Cu interface region is accomplished by combining focused ion beam
sectioning and imaging with ion-induced secondary electrons. Successful bonding of Cu-based HARMSs to flat Cu plates with
Sn intermediate layers is demonstrated, as well as assembly of all-Cu microfluidic prototypes.
Microsystem Technologies 04/2012; 15(7):1111-1118. · 0.93 Impact Factor
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ABSTRACT: A single-crystal Al specimen was indented at room temperature with a series of prismatic diamond indenters. The indenters had tri-angular or wedge-shaped cross-sections and were relatively long, thus inducing a two-dimensional (2-D) plane-strain response. Different included wedge angles were used. For each wedge indenter, instrumented indentations were carried out at varying loads. Analysis of the response from each wedge indentation experiment clearly revealed the presence of a size effect, manifested in an increasing projected con-tact pressure as the contact dimensions decreased from micron to submicron scales. When indentation responses from 2-D wedge ind-enters with different included angles were compared, the data showed evidence that this indentation size effect depended on the included wedge angle. This dependence was analyzed and compared to existing models of indentation based on the concept of geometrically nec-essary dislocations. While the model prediction of the dependence of the characteristic length on the included wedge angle appears to be consistent with current experiments, the model estimate of the magnitude of the characteristic length significantly exceeds the value deduced from experimentation. The present results offer new experimental evidence of size-dependent indentation response in plane-strain geometries.
Acta Materialia 01/2012; · 3.76 Impact Factor
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ABSTRACT: To evaluate the effect of vitamin A, vitamin A plus iron and "7 + 1" multiple micronutrient-fortified seasoning powder on iron metabolic homeostasis in preschool children.
This was a randomized, controlled and blinded interventional field trial. A total of 226 2 - 7 years old preschool children were recruited from three nurseries in the area, and they were randomly assigned into three different fortified diet groups for 6 months. The subjects in Group I were fortified with vitamin A; those in Group II and III were fortified with vitamin A plus iron and vitamin A plus iron, thiamine, riboflavin, folic acid, niacinamide, zinc and calcium (7 + 1), respectively. The concentration of serum vitamin A was measured by high-performance liquid chromatography (HPLC), serum ferritin (SF) was measured by enzyme-linked immunosorbent assay (ELISA), soluble transferrin receptor (sTfR) was measured by microparticle-enhanced, and hemoglobin (HB) by hemiglobincyanide, the sTfR-SF index (TFR-F index) and total body iron content were computed respectively before and after intervention. Simultaneously, children's demographic data, socio-economic status and eating habits, etc. were investigated by questionnaires.
A total of 226 preschool children were included in the study with age ranged from 2 to 7 years with average age (4.0 ± 0.85) (means ± standard deviation). The prevalence of anemia, deficient iron storage, vitamin A deficiency (VAD) and suspect sub-clinical vitamin A deficiency (SSVAD) were 23.5%, 15.0%, 6.3% and 25.9%, respectively. The levels of SF and sTfR significantly decreased after intervention in all groups (χ(2) = 8.3298, χ(2) = 16.1471, χ(2) = 15.1371, χ(2) = 15.1171, χ(2) = 5.2617, χ(2) = 4.8844, P < 0.05) especially in groupIIand group III for SF (χ(2) = 16.1471, χ(2) = 15.1371, P < 0.05) and group I for sTfR (χ(2) = 15.1171, P < 0.05). No marked change of TFR-F index and total body iron contents was observed in group I (t = 0.1817, t = 1.7736, P > 0.05), while TFR-F index decreased and total body iron contents increased in group II and group III (t = 5.3561, t = 6.5979, t = 11.1663, t = 8.7306, P < 0.05) after intervention.
Vitamin A intervention has significant effect on iron storage and mobilization but seldom effect on iron absorption in small intestine. The combination of vitamin A and other micronutrients might be a better intervention for the improvement of iron deficiency for preschool-children.
Zhonghua er ke za zhi. Chinese journal of pediatrics 12/2011; 49(12):926-32.
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ABSTRACT: Improvement of hemoglobin and serum retinol and facilitation of the mobilization of iron storage were achieved with a multiple-micronutrient-fortified diet in preschoolers for 6 mo in a suburb of Chongqing, China. We investigated whether fortification with multiple micronutrients in a diet for preschool children results in changes in children's infectious morbidity compared with diets fortified solely with vitamin A and with vitamin A plus iron.
From December 2005 to June 2006, 226 2- to 6-y-old preschool children were recruited from three nurseries randomly assigned to three different fortified-diet groups for 6 mo. Group I was fortified with vitamin A; groups II and III were fortified with vitamin A plus iron and vitamin A plus iron, thiamine, riboflavin, folic acid, niacinamide, zinc, and calcium, respectively. The secondary functional outcomes, morbidity of diarrhea and respiratory infection, were collected during supplementation.
The groups were comparable concerning compliance and loss to follow-up. There was evidence of a lower incidence rate of respiratory-related illnesses, diarrhea-related illness, fewer symptoms of runny nose, cough, and fever, and shorter duration of respiratory-related illnesses and cough for children in group III compared with children in groups I and II. However, there was no significantly or clinically important difference between children in groups I and II.
The beneficial effects on infectious morbidity over 6 mo, in addition to some biochemical improvements, highlight the potential of this micronutrient-fortified seasoning powder supplied in a diet for preschool children.
Nutrition 04/2011; 27(4):428-34. · 3.03 Impact Factor
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ABSTRACT: This study examined whether pregnancy-related marginal vitamin A deficiency (MVAD) influences postnatal development of retinoic acid receptors (RARs) and N-methyl-D-aspartate (NMDA) receptor subunit 1 (NR1) in hippocampus of rat pups. Sixteen female rats were randomized equally into control and MVAD groups. Dams and pups were fed with either a normal control diet or one deficient in vitamin A. Eight female pups in each group were killed at 1 day, 2 weeks, 4 weeks and 8 weeks after birth, respectively. Serum retinol levels were monitored. The messenger RNA (mRNA) and protein expressions and subcellular localization of RARα, RARβ and NR1 in postnatal hippocampus were detected. At 1 day, 2 weeks and 8 weeks after birth, serum retinol levels in the MVAD group were significantly lower than those in the control group. Results of Morris water maze test at 7 weeks of age showed that spatial learning and memory in the MVAD group were affected. Vitamin A deficiency resulted in decreased mRNA levels of RARα, RARβ and NR1 (P<.05). The protein level of RARα and NR1 in the MVAD group was lower than that of the control group (P<.05). There was no significant difference in RARβ between the groups (P>.05). A mass of RARα and NR1 colocalized in hippocampal cell cytoplasm on postnatal day 1. Our data suggested that vitamin A deficiency in pregnancy may affect the postnatal expression of RARα and NR1, affecting learning and memory function in the hippocampus and synaptic plasticity of the calcium signaling pathway.
The Journal of nutritional biochemistry 02/2011; 22(12):1112-20. · 4.29 Impact Factor
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ABSTRACT: A single crystal Al specimen was molded at room temperature with long, rectangular, strip diamond punches. Quantitative molding response curves were obtained at a series of punch widths, ranging from 5 lm to 550 nm. A significant size effect was observed, mani-festing itself in terms of significantly increasing characteristic molding pressure as the punch width decreases to 1.5 lm and below. A detailed comparison of the present strip punch molding results was made with Berkovich pyramidal indentation on the same single crys-tal Al specimen. The comparison reveals distinctly different dependence of the characteristic pressure on corresponding characteristic length. The present results show the feasibility of micro-/nano-scale compression molding as a micro-/nano-fabrication technique, and offer an experimental test case for size-dependent plasticity theories.
Acta Materialia 12/2010; · 3.76 Impact Factor
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ABSTRACT: Low-profile, Cu-based microchannel heat exchangers (MHEs) with different geometric dimensions were fabricated, bonded and assembled. A transient liquid phase (TLP) process was used for bonding of Cu-based MHEs with total thicknesses ranging from 600 µm to 1700 µm. The structural integrity of TLP-bonded Cu MHEs was examined. Device-level heat transfer testing was performed on a series of Cu-based MHEs to study the influence of microchannel dimensions on overall heat transfer performance, corroborated by computational results from a simple 2D finite element analysis. The present results demonstrate the promise of low-profile metallic MHEs for high heat flux cooling applications.
Journal of Micromechanics and Microengineering 10/2010; 20(11):115002. · 2.11 Impact Factor
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ABSTRACT: To investigate the efficacy of biscuits fortified with different doses of vitamin A on improving vitamin A deficiency (VAD), anaemia and physical growth of pre-school children.
A randomised double-masked population-based field interventional trial with a positive control group.
Banan district of Chongqing, China.
A total of 580 pre-school children aged 3-6 years were randomly recruited into four groups. Children in groups I and II were given biscuits fortified with vitamin A at 30 % of the recommended daily intake (RDA) and 100 % of the RDA once a day for 9 and 3 months, respectively. Children in group III received biscuits containing 20,000 IU of vitamin A once a week for 3 months. Initially, the children in group IV received a 200,000 IU vitamin A capsule just once. At the beginning and end of the study, blood samples were collected to measure Hb, serum retinol, retinol-binding protein and prealbumin, and weight and height were measured.
All the fortification types significantly decreased the prevalence of VAD and anaemia in each group (P < 0.05). The effect of 9-month intervention on group I was the most efficient (P < 0.0045). After intervention, the Z-scores of height-for-age, weight-for-age and weight-for-height in all groups increased markedly compared with baseline (P < 0.05), but no significant difference was observed among the groups.
Data indicated that consuming vitamin A-fortified biscuits with daily 100 % RDA for 3 months has the same effect on the improvement of VAD, anaemia and physical growth as did the weekly 20,000 IU and single 200,000 IU administration in pre-school children.
Public Health Nutrition 09/2010; 13(9):1462-71. · 2.17 Impact Factor
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ABSTRACT: Anemia is a widespread public health problem, which is due to many factors, nutritional or non-nutritional. Iron, vitamin A and growth status were assessed to investigate anemia of preschool children in suburb Chongqing, China.
A descriptive, cross-sectional survey was performed on 459 preschool children aged 2 to 7 years randomly chosen from the kindergartens in 6 suburban districts of Chongqing. Weight and height levels, hemoglobin, erythrocyte protoporphyrin, serum retinol, and ferritin concentrations were measured to evaluate the anthropometric and nutritional status.
The rates of stunt, underweight, overweight, wasting, obesity, anemia, iron deficiency, vitamin A deficiency (VAD), and marginal VAD were 6.3%, 3.9%, 3.7%, 1.5%, 3.1%, 23.5%, 15.0%, 6.3% and 25.9%, respectively. Serum retinol concentration was significantly lower in children with anemia than in those without anemia (P=0.003), and the retinol concentration was associated with hemoglobin (Pearson's correlation coefficient, r=0.22, P<0.01). Children with VAD had a significantly increased risk for anemia (odds ratio, 2.56; 95% confident interval, 1.15-5.70). In all 108 children with anemia, only 42 were related to VAD and 12 related to iron deficiency, suggesting that almost half of the anemia children cannot be explained solely by iron deficiency or VAD.
Vitamin A and iron deficiency are still public health problems in some localities of China. Public health interventions in anemia control should be used to eliminate deficiencies of vitamin A, iron, and other micronutrients by deliberate supplementation. Attention must be paid to such deficiencies in high-risk groups, especially in preschool children.
World Journal of Pediatrics 11/2009; 5(4):275-81. · 1.22 Impact Factor
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ABSTRACT: Information about the effect of antioxidant vitamins nutrition during pregnancy on offsprings intellectual development is extremely limited.
To investigate the correlation of antioxidant vitamins (Vitamin A, E and C) at delivery and the neurodevelopment of early childhood.
A total of 158 paired maternal-neonatal subjects were recruited. The serum concentrations of vitamin A, E and C in maternal and cord blood after delivery were determined and intellectual development was evaluated by Gesell Development Schedule (GDS) at two years old.
After adjusting for potential confounders, vitamin A placental transport ratio (VA-PTR) was positively associated with motor area development quotients (DQ) and average DQ(p<0.01). Cord VA level was positively related with language area and social area DQ (p<0.05). Nevertheless, there was no significant association between cord VE, VC levels, VE PTR or VC PTR and GDS. The adaptive area and average DQ in high cord VA group was higher than those in low VA group (p<0.05). Cord VA level and VA-PTR were positively associated with birth head circumference and birth weight, respectively.
Our data suggested that adequate vitamin A at delivery had beneficial influence on neonatal birth outcomes and children's neurodevelopment in later childhood.
International Journal for Vitamin and Nutrition Research 07/2009; 79(4):238-49. · 0.88 Impact Factor
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ABSTRACT: To investigate the correlation of the antioxidant vitamins status (vitamins A, E and C) during pregnancy and the intellectual development of early childhood.
A total of 150 paired maternal-neonatal subjects were recruited into the present study. The serum concentrations of antioxidant vitamins (vitamins A, E and C) in maternal blood and cord blood after delivery were determined by high performance liquid chromatography and the intellectual development was evaluated by Gesell Development Schedules (GDS) at two-years-old.
Children with higher cord serum vitamin E level showed higher scores of motor, adaptive domain and average compared to children with lower cord serum vitamin E level (p<0.01 or 0.05), respectively. Cord serum vitamin A level had significant positive correlation with effect on motor DQs (beta=4.227, p<0.05), and vitamin E level in cord blood showed a positive relation with motor DQ and average DQ (beta=0.329 and 0.1875, respectively, p<0.05) in multiple linear regression model. The language and social DQs were influenced by placental vitamin E transport rate (beta=3.1968 and 3.0194, respectively, p<0.05). The placental transport rate of vitamin E also was a protective factor for the prevalence of motor behavior developmental delay [OR: 0.118, 95% confident interval (95% CI), 0.018-0.765, p=0.0251], personal and social behavior developmental delay (OR: 0.052, 95% CI: 0.004-0.610, p=0.0185) and average developmental delay (OR: 0.041, 95% CI: 0.003-0.642, p=0.0229) in logistic multiple regression model.
Data suggested that vitamin A, E status and vitamin E transfer rate at delivery had beneficial influence on children's cognitive and behavior development quotients.
Early human development 04/2009; 85(7):421-7. · 2.12 Impact Factor
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ABSTRACT: Preschool children in developing countries are likely to have multiple, concurrent micronutrient deficiencies. This study was designed to evaluate the effectiveness of different combinations of nutritional fortified diet to improve the blood levels of iron, vitamin A and other essential micronutrients in the preschool population of Banan District of Chongqing, China. From December 2005 to June 2006, a total of 226 2-6 y old preschool children were recruited from three nurseries in the area, and they were randomly assigned to three different fortified diet groups for 6 mo. Group I was fortified with vitamin A; groups II and III were fortified with vitamin A plus iron and vitamin A plus iron, thiamine, riboflavin, folic acid, niacinamide, zinc and calcium, respectively. Subjects' weight and height were measured for assessing the children's growth and development. Blood samples were taken at the beginning and the end of the 6-mo study period for measuring serum levels of micronutrients. Group III with the multiple micronutrient fortified diet was the most effective to improve the serum level of retinol from [media (P25, P75): 1.06 (0.89, 1.32)] micromol/L to 1.29 (1.04, 1.39) micromol/L (p<0.05) and retinol binding protein from 17.0 (12.6, 25.6) mg/L to 31.6 (24.4, 44.0) mg/L (p<0.05) and to mobilize the stored iron in the liver (p<0.05). In addition, the three groups' hemoglobin levels were elevated from 117.0 (109.0, 124.1) g/L, 114.0 (109.2, 119.7) g/L and 115.0 (109.5, 122.7) g/L to 125.7 (119.2, 133.1) g/L, 126.5 (122.2, 135.9) g/L and 125.1 (119.8, 131.6) g/L over the 6 mo of intervention period, but there were no difference among the three groups (p>0.05). Nevertheless, unexpected results were obtained when comparing the effects on growth status among the different supplement groups. Our study has demonstrated that a multiple micronutrient fortified diet for 6 mo is more effective to improve the levels of hemoglobin, serum retinol, and RBP as well as to facilitate the mobilization of iron storage in preschool children.
Journal of Nutritional Science and Vitaminology 12/2008; 54(6):440-7. · 1.20 Impact Factor
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Hongmei Huang,
Hua Wei,
Xuan Zhang, Ke Chen,
Yasha Li,
Ping Qu,
Xiaoping Zhang,
Jie Chen,
Youxue Liu,
Li Yang,
Tingyu Li
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ABSTRACT: Retinoic acid receptors (RARs) are reported to mediate the effects of retinoid acid and participate in the maintenance of normal hippocampal function during embryonic and postnatal stages. RARalpha is the only one that has been reported to be continuously expressed among RARs in the CA1-CA3 areas of the hippocampus, at both the mRNA and the protein level. Here, we show the expression and subcellular localization of RARalpha in granule and pyramidal cells in various regions of the hippocampus during postnatal development of rats. We discovered that the expression level of RARalpha in postnatal hippocampal tissue gradually decreased over time with increasing developmental maturity of the nervous system. Moreover, the subcellular localization of RARalpha expression showed a phenomenon of intracellular translocation during the postnatal development period. This new discovery is inconsistent with a traditional viewpoint according to which RARalpha, as a nuclear transcription factor, is mainly expressed inside nucleus. This phenomenon suggests that RARalpha may have different actions during each stage of hippocampal development.
Brain Research 07/2008; 1227:26-33. · 2.73 Impact Factor
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ABSTRACT: A numerical model based on the dual reciprocity boundary element method (DRBEM) is presented here for the study of combined wave diffraction and refraction. The model is more general than that presented by Zhu [Zhu S-P. Engng Anal Boundary Elements 1993;12:261–274] in the sense that areas or coastlines where water depth is zero can be dealt with as well. Our comparative study show that the new model is very accurate for long waves (tsunami waves). It is numerically very efficient in comparison with models based on finite elements too. Using the new model, the interaction between the diffraction and refraction effects is examined. It is shown that the diffraction effect is significantly enhanced when there is a combined diffraction and refraction than when there is just diffraction alone.
Engineering Analysis with Boundary Elements.
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ABSTRACT: In this paper, the boundary element dual reciprocity method (BEDRM) is introduced for the solution of a class of boundary value problems. Convergence analysis of the BEDRM is carried out for Poisson's equation with Dirichlet boundary condition, using some important results on radial basis function approximation.
Engineering Analysis with Boundary Elements.
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ABSTRACT: Replication of metallic high-aspect-ratio microscale structures by direct compression molding is a promising microfabrication technique. In this paper, the micromolding response of elemental Cu is measured as a function of molding temperature. Companion tensile testing of macroscale Cu specimens was carried out at the corresponding molding temperatures. Microstructures of tensile tested macroscale Cu specimens and molded Cu specimens were characterized by combining focused ion beam (FIB) sectioning and imaging with ion-induced secondary electrons (ISEs). At all temperatures tested, measured tensile stress–strain curves for Cu show clear evidence for the occurrence of dynamic recrystallization (DRX) within macroscale tensile specimens. Additional FIB sectioning and imaging with ISEs of molded Cu specimens provide microstructural evidence for the occurrence of DRX during molding. The present results show that, even in the presence of DRX, an appropriate one-parameter scaling continues to reduce the molding response to a universal function independent of the molding temperature.
Acta Materialia.
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ABSTRACT: Giant magnetoresistance (GMR) and magnetic properties in Fe/In/Fe trilayers with various In thickness were studied. Negative GMR 0.38% was observed in sample with In thickness 1.05 nm at 20 K. The magnitudes of GMR were found to oscillate with a period about 1.1 nm when varying the thickness of In layers. The GMR of trilayers was near constant at low temperature and decreased linearly with increasing temperature at high temperature.
Journal of Alloys and Compounds.
