Synthesis of hydroxyapatite nanoparticles with tailorable morphologies and carbonate substitutions using a wet precipitation method

Hydroxyapatite (HA) nanoparticles with different morphologies and variant levels of carbonate substitutions were synthesized using a wet precipitation method by adjusting the heating temperature and/or the initial ion concentration of the reaction system. Within the particles, crystalline domains with different lengths were aligned along each other and formed into nanoparticles with different sizes, shapes and topographies. Different from most reported studies, the nucleation, growth and morphology of the crystalline domains were found sensitive to heating temperature, but not significantly influenced by initial ion concentration within the studied range. The OH- and PO4(3-) ions within the HA particles were partially substituted by CO3(2-) ions. The substitution was dominated by the replacement of OH- instead of PO4(3-) in HA. The carbonate substitution was found to decrease with increasing heating temperature and/or initial ion concentration. Therefore, both the morphology and composition of the HA particles can be tailored by controlling the heating temperature and/or the initial ion concentration in the reaction system. Such synthesized HA nanoparticles can be used as biomaterials for bone tissue engineering.     

Physiological down-regulation and positive emotion in marital interaction.

Previous studies have demonstrated that 1 function of positive emotion is the undoing of physiological arousal produced by negative emotions. These studies have used single-subject paradigms, in which emotions were induced by films in college-age individuals. In the present study, we examined the relationship between physiological down-regulation and positive emotion in a sample of 149 middle-aged and older married couples engaged in a 15-min discussion of an area of marital conflict. During the conversation, autonomic and somatic physiological activity was measured, and emotional behaviors were recorded and subsequently coded. We found that during 20-s periods of down-regulation (where physiology transitioned from high arousal to low arousal), couples showed an increase in positive emotional behavior compared with periods without down-regulation. The finding was quite robust, suggesting that the undoing effect of positive emotion generalizes across age, sex, and marital satisfaction. The advantages of using positive emotion as an emotion regulation strategy are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of family foundations on parents and children: 3.5 years after baseline.

This study investigated the ability of a psychosocial prevention program implemented through childbirth education programs to enhance the coparental and couple relationship, parental mental health, the parent-child relationship, and child outcomes. A sample of 169 heterosexual, adult couples expecting their first child was randomized to intervention and control conditions. The intervention families participated in Family Foundations, a series of eight classes delivered before and after birth, which was designed as a universal prevention program (i.e., applicable to all couples, not just those at high risk). Intent-to-treat analyses utilizing data collected from child age 6 months through 3 years indicated significant program effects on parental stress and self-efficacy, coparenting, harsh parenting, and children's emotional adjustment among all families, and maternal depression among cohabiting couples. Among families of boys, program effects were found for child behavior problems and couple relationship quality. These results indicate that a universal prevention approach at the transition to parenthood focused on enhancing family relationships can have a significant and substantial positive impact on parent and child well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An evaluation of the effectiveness of a chemical additive based on sodium benzoate,potassium sorbate,and sodium nitrite on the fermentation and aerobic stability of corn silage

We evaluated the effectiveness of an additive comprising sodium benzoate, potassium sorbate, and sodium nitrite (SSL) as active ingredients for its ability to improve the aerobic stability of corn silages made in North America. In experiment 1, treatment with SSL (1.5 and 2.0 L/t) on whole-plant corn (WPC) was compared with treatment with an additive containing buffered propionic acid and citric acid (BPA; 2 L/t) on corn harvested at 32 and 38% dry matter and ensiled for 120 d. Silage treated with BPA was higher in ammonia-N and propionic acid relative to other treatments. Treatments with all of the additives had numerically, but not statistically, fewer yeasts compared with untreated silage. Both application rates of SSL resulted in lower concentrations of ethanol compared with untreated and BPA silages. Treatment with BPA improved the aerobic stability of silages compared with untreated silage, but the effect from SSL was markedly greater. In experiment 2, WPC was untreated or treated with 2 or 3 L of SSL/t or a microbial inoculant containing Enterococcus faecium M74, Lactobacillus plantarum CH6072, and Lactobacillus buchneri LN1819 (final total lactic acid bacteria application rate of 150,000 cfu/g of fresh forage). Silages were air stressed for 24 h at 28 and 42 d of storage and ensiled for 49 d before opening. Inoculation had no effect on acid end products, ethanol, number of yeasts, or aerobic stability compared with other treatments. Treatment with SSL decreased the amount of ethanol, had no effect on number of yeasts, and improved aerobic stability in a dose-dependent manner compared with other treatments. In experiment 3, WPC was untreated or treated with 2 L of SSL/t and ensiled for 5, 15, and 30 d. Treatment with SSL resulted in silage with fewer yeasts and lower concentrations of ethanol after all times of ensiling compared with untreated silage. In addition, SSL improved aerobic stability after each period of ensiling, but the effect was more at 15 and 30 d compared with 5 d of storage. Treating WPC with SSL can improve the aerobic stability of corn silage made in North America, and the effect can be observed as soon as 5 d after ensiling.     

Understanding the Effect of Grain Boundary Character on Dynamic Recrystallization in Stainless Steel 316L

Dynamic recrystallization (DRX) occurs during high-temperature deformation in metals and alloys with low to medium stacking fault energies. Previous simulations and experimental research have shown the effect of temperature and grain size on DRX behavior, but not the effect of the grain boundary character distribution. To investigate the effects of the distribution of grain boundary types, experimental testing was performed on stainless steel 316L specimens with different initial special boundary fractions (SBF). This work was completed in conjunction with computer simulations that used a modified Monte Carlo method which allowed for the addition of anisotropic grain boundary energies using orientation data from electron backscatter diffraction (EBSD). The correlation of the experimental and simulation work allows for a better understanding of how the input parameters in the simulations correspond to what occurs experimentally. Results from both simulations and experiments showed that a higher fraction of so-called “special” boundaries (e.g., Σ3 twin boundaries) delayed the onset of recrystallization to larger strains and that it is energetically favorable for nuclei to form on triple junctions without these so-called “special” boundaries.     

Dispersive optical solitons by the semi-inverse variational principle

In this paper an analytical expression for an optical soliton is obtained with the aid of He's semi-inverse variational principle in the presence of third- and fourth-order dispersion as well as inter-modal dispersion. Three laws of nonlinear media are considered in this paper: the Kerr law, the power law and the log law.     

Flow cytometric analysis to detect pathogens in bacterial cell mixtures using semiconductor quantum dots

Compared to a common green organic dye, semiconductor quantum dots (QDs) composed of CdSe/ZnS core/shell bioconjugates display brighter fluorescence intensities, lower detection thresholds, and better accuracy in analyzing bacterial cell mixtures composed of pathogenic E. coli O157:H7 and harmless E. coli DH5alpha using flow cytometry. For the same given bacterial mixture, QDs display fluorescence intensity levels that are approximately 1 order of magnitude brighter compared to the analogous experiments that utilize the standard dye fluorescein isothiocyanate. Detection limits are lowest when QDs are used as the fluorophore label for the pathogenic E. coli O157:H7 serotype: limits of 1% O157:H7 in 99% DH5alpha result, corresponding to 106 cells/mL, which is comparable to other developing fluorescence-based techniques for pathogen detection. Finally, utilizing QDs to label E. coli O157:H7 in cell mixtures results in greater accuracy and more closely approaches the ideal fluorophore for pathogen detection using flow cytometry. With their broader absorption spectra and narrower emission spectra than organic dyes, QDs can make vast improvements in the field of flow cytometry, where single-source excitation and simultaneous detection of multicolor species without complicating experimental setups or data analysis is quite advantageous for analyzing heterogeneous cell mixtures, both for prokaryotic pathogen detection and for studies on eukaryotic cell characteristics.     

Growth, yield and seed composition of native Australian legumes with potential as grain crops

BACKGROUND: Many Australian native legumes grow in arid and nutrient‐poor environments. Yet few Australian herbaceous legumes have been investigated for domestication potential. This study compared growth and reproductive traits, grain yield and seed composition of 17 native Australian legumes with three commercial grain legumes. RESULTS: Seed yields of seven native legumes were > 40% of Cicer arietnum, with highest seed yields and harvest indices in Glycine sp. (14.4 g per plant, 0.54 g g^?1) and Lotus cruentus (10.2 g per plant, 0.65 g g^?1). Five native species flowered earlier than field pea (Pisum sativa) (109 days), though many were slower to flower and set seed. Largest seeds were found in Glycine canescens (17 mg), with seed of other native species 14 times smaller than commercial cultivars. Seed composition of many native legumes was similar to commercial cultivars (200–330 g protein kg^?1 dry weight (DW), 130–430 g dietary fibre kg^?1 DW). Two Cullen species had high fat content (>110 g kg^?1 DW) and Trigonella sauvissima had the highest crude protein content (370 g kg^?1 DW). CONCLUSION: The seed composition and reproductive traits of some wild native Australian legumes suggest they could offer potential as grain crops for soils and environments where the current grain legumes are uneconomic. Further evaluation of genetic diversity, especially for seed size, overall productivity, and reproductive development is needed. Copyright © 2011 Society of Chemical Industry