Effects of Thermoelectric Magnetic Convection on the Solidification Structure During Directional Solidification under Lower Transverse Magnetic Field

This work investigated the thermoelectric magnetic convection (TEMC) during directional solidification under a transverse magnetic field numerically and experimentally. Numerical results show that the TEMC will form in liquid near the liquid/solid interface and in the dendritic network. The value of the TEMC mainly depends on the crucible diameter, the temperature gradient, and the magnetic field intensity. The value of the TEMC increases as the crucible diameter and the temperature gradient are increased. The value of the TEMC on the sample scale increases to a maximum when the magnetic field is of the order of 0.1 T, and then decreases as the magnetic field still increases. However, the value of the TEMC on the cell/dendrite scale continues to increase with the increase of the magnetic field intensity when the applied magnetic field is less then 1 T. Two alloys are solidified directionally in the vertical configuration under a transverse magnetic field, and results show that the application of a lower transverse magnetic field (B < 1 T) modified the liquid/solid interface shape and the cellular/dendritic array significantly. Indeed, it was observed that, along with the refinement of the cell/dendrite, the magnetic field caused the deformation of the liquid/solid interfaces and the extensive segregations (i.e., channel and freckle) in the mushy zone. Comparison of the numerical and experimental results shows that the modification amplitude of the liquid/solid interface and the cellular/dendritic morphology is in good agreement with the value of the TEMC at the liquid/solid interface and in the dendritic network. This implies that changes of the interface shape and the cellular/dendritic morphology should be attributed, respectively, to the TEMC on the sample and the cell/dendrite scales.     

In vitro evaluation of bioactive strontium-based ceramic with rabbit adipose-derived stem cells for bone tissue regeneration

The development of bone replacement materials is an important objective in the field of orthopaedic surgery. Due to the drawbacks of treating bone defects with autografts, synthetic bone graft materials have become optional. So in this work, a bone tissue engineering approach with radiopaque bioactive strontium incorporated calcium phosphate was proposed for the preliminary cytocompatibility studies for bone substitutes. Accumulating evidence indicates that strontium containing biomaterials promote enhanced bone repair and radiopacity for easy imaging. Hence, strontium calcium phosphate (SrCaPO₄) and hydroxyapatite scaffolds have been investigated for its ability to support and sustain the growth of rabbit adipose-derived mesenchymal stem cells (RADMSCs) in vitro. They were characterized via Micro-CT for pore size distribution. Cells used were isolated from New Zealand White rabbit adipose tissue, characterized by FACS and via differentiation into the osteogenic lineage by alkaline phosphatase, Masson’s trichome, Alizarin Red and von Kossa staining on day 28. Material-cell interaction was observed by SEM imaging of cell morphology on contact with material. Live–Dead analysis was done by confocal laser scanning microscopy and cell cluster analysis via μCT. The in vitro biodegradation, elution and nucleation of apatite formation of the material was evaluated using simulated body fluid and phosphate buffered saline in static regime up to 28 days at 37 °C. These results demonstrated that SrCaPO₄ is a good candidate for bone tissue engineering applications and with osteogenically-induced RADMSCs, they may serve as potential implants for the repair of critical-sized bone defects.     

Using liposomal fluorescent biolabels to develop an immunoaffinity chromatographic biosensing system for biotin

Although biotin is an important vitamin for cellular function and growth, there are no rapid, simple, and reliable analytical tools available for its quantitation in bodily fluids or foodstuffs. In this study, we developed an immunoaffinity chromatographic biosensing system for the direct determination of biotin. A stationary phase having affinity for biotin was synthesized by covalently bonding antibiotin monoclonal antibodies onto 90-microm, NHS-activated sepharose beads. The beads were then packed into 1.9-cm-diameter plastic tubes to form a column having a volume of 3.0 mL. The function of the proposed immunoaffinity chromatographic assay was based on competition between biotin and carboxyfluorescein (CF)-encapsulated, biotin-tagged liposomes (liposomal biolabels) for the limited number of antibiotin antibody binding sites. Buffers containing biotin standards at concentrations ranging from 10(-12) to 10(-3) M were passed through the column to trap and concentrate the biotin on the solid support. The unbound binding sites of the antibody were then occupied through subsequent addition of the liposomal biolabels. The addition of 35% methanol released the CF molecules from the lyzed bound liposomes; the fluorescence intensity of the released markers was then measured using a fluorometer. The calibration curve for biotin was linear over 8 orders of magnitude, from 10(-12) to 10(-4) M. The limit of detection of this immunoaffinity chromatographic biosensing system reached as low as 5.0 pg of biotin (equivalent to 500 microL of 4.10 x 10(-11) M biotin).     

A dimensional approach to maternal attachment state of mind: Relations to maternal sensitivity and maternal autonomy support.

The aim of this study was to examine the developmental significance of the newly developed dimensional approach to attachment state of mind by investigating its capacity to predict individual differences in the quality of two caregiving behaviors—maternal sensitivity and maternal autonomy support—that are linked to numerous important child outcomes. Seventy-one upper-middle-class, predominantly French-speaking and Caucasian dyads participated in 3 home visits (34 girls). The Adult Attachment Interview (AAI) was administered when the infants were 8 months old, maternal sensitivity was assessed when they were 12 months old, and maternal autonomy support was assessed at 15 months. The results revealed that, above and beyond SES, maternal sensitivity was negatively related to the dismissing dimension of the AAI, whereas maternal autonomy support was negatively linked to the preoccupied/unresolved dimension. In contrast, the traditional AAI categories were not significantly linked to parenting. These results speak to the relevance of using a continuous approach to attachment state of mind when predicting individual differences in specific caregiving behaviors. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Does hemodiafiltration improve the removal of homocysteine?

High prevalence of hyperhomocysteinemia is common in hemodialysis (HD) patients and could contribute to worsen the cardiovascular risk. Beyond vitamin B status, dialysis modality itself could influence homocysteine (Hcy) levels. The objective was compare the reduction rate (RR) of Hcy and cysteine in stable dialyzed patients treated by standard HD or hemodiafiltration (HDF). Seventy‐five patients undergoing stable dialysis through standard high‐flux HD (n = 35) or HDF (n = 40) were included. Biological parameters were determined before and after a midweek dialysis session. Urea percent reduction per session and Kt/V index (K, body urea clearance, T, time of dialysis, and V, urea distribution volume), defined as a marker of dialysis efficacy, were similar between HD and HDF groups. By contrast, higher RR of beta2 microglobulin (β2m) was observed in HDF compared with HD (78.6 vs. 72.0%, respectively; P < 0.001). Likewise, higher RR of Hcy was obtained with HDF compared to HD (46.0 vs. 41.5%, respectively; P < 0.05), whereas the RR of cysteine was similar in both groups. Interestingly, a positive correlation between Hcy RR and urea Kt/V index was observed (r = 0.29, P < 0.05) and between Hcy RR and β2m RR (r = 0.45, P < 0.001). Time‐averaged concentration (TAC) of Hcy was lower with HDF compared with HD (17.8 vs. 19.1 μmol/L, respectively), although not significant. There was no difference in median Hcy according to dialysis modality for neither pre‐ nor postdialysis levels. Significant higher removal of Hcy was observed with HDF compared with standard HD, although urea Kt/V index was similar. Enhanced removal of middle molecules, such as β2m, could be involved in Hcy RR improvement with HDF.     

L'appariement des styles de motivation et l'évolution de la satisfaction conjugale.

Examined whether couples tend to adopt self-determined motivational styles and observed the relationship between couples, motivation style pairings and marital satisfaction. The sample consisted of 226 married or cohabiting couples participating on a voluntary basis. 87 couples completed the questionnaires a 2nd time 36 mo later. The instruments used were the Couple Motivation Questionnaire and the Dyadic Adjustment Scale. Results showed that there is a significant relationship between women's and men's motivations to live together. The most frequent couples' pattern of pairing was 2 people with self-determined motivational styles. Furthermore, this couple pattern was related to higher marital satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Qualitative reports of problems in cohabiting relationships: Comparisons to married and dating relationships.

Although previous research has demonstrated increased relationship distress and separation for cohabiting couples, little is known about specific problems cohabiting individuals encounter in comparison to dating and married individuals. This study examines open-ended reports of 1,252 individuals' (220 dating, 231 cohabiting, and 801 married) relationship concerns using a detailed, reliable coding system. The top 5 areas considered most problematic by cohabiting individuals were problems in specific areas of their current relationship, individual problems, general communication, arguments, and emotional affection–distance. Dating and cohabiting individuals reported similar frequencies of global problems except that cohabiting individuals reported more problems with arguments and fewer problems with relationship commitment. Married and cohabiting individuals had more differences in their reports of relationship concerns; results suggested that cohabiting relationships tended to be both more vibrant and more volatile than marital relationships. However, most differences between relationship types were no longer significant after controlling for individuals' relationship and demographic characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attending to the exploration side of infant attachment: Contributions from self-determination theory.

Understanding the intergenerational transmission of attachment patterns has been a main focus of attachment research for many years. Most of the empirical work conducted on this question has addressed maternal sensitivity to infants’ attachment needs. Given that security of attachment is defined as an attachment/exploration balance, some researchers have stressed the need to explore maternal behaviours in the context of infant exploration. The authors propose that self-determination theory (SDT) could contribute to attachment work in this respect given that it has clearly operationalized parental exploration-related behaviours and has related them to numerous child outcomes. This article highlights conceptual, empirical, and methodological parallels that can be drawn between SDT and attachment theory, thus suggesting that they could be complementary on many levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)