Association of microstructure and electric heterogeneity in BiFeO3

BiFeO₃ ceramics was synthesized by solid state reaction technique. Synchrotron X-ray diffraction analysis was employed to investigate the phase formation and structure determination. Rietveld refinement of the diffracted data confirmed the rhombohedrally distorted perovskite structure with space group R3c. Localized atomic structure determined from fitted X-ray data showed off centered displacement of Fe³⁺ cations with a magnitude of 0.397 Å along c-axis. The FeO₆ octahedron comprised of two types of Fe–O bonds with bond lengths of ∼1.935 Å and ∼2.131 Å. Impedance spectroscopic data collected in wide temperature (300–400 K) and frequency (200 Hz–2 MHz) ranges, demonstrated two relaxation phenomena corresponding to two heterogeneous phases. The best fits to the collected impedance data were achieved by employing an equivalent circuit model R_g(R_gbC_gb)(R_eQ_e). Grain boundaries showed only p-type small polaronic hopping conduction process assisted with the oxidation of Fe³⁺ to Fe⁴⁺ in measured temperature range of 300–400 K. Grains exhibited p-type small polaronic hopping conduction mechanism up to 375 K; however, above 375 K electronic conduction becomes prominent. Conduction is dominated by short range hopping of the polarons among Fe³⁺ and Fe⁴⁺ or through the first ionized oxygen vacancy bridge between Fe³⁺ and Fe²⁺ cations.     

Highly active three-dimensional cage type mesoporous aluminosilicates and their catalytic performances in the acetylation of aromatics

Three-dimensional cage type mesoporous aluminosilicates (AlKIT-5) with different n_Si/n_Al ratios have been successfully synthesized hydrothermally using pluronic F127 as a template under highly acidic medium [P. Srinivasu, S. Alam, V.V. Balasubramanian, S. Velmathi, D.P. Sawant, W. Böhlmann, S.P. Mirajkar, K. Ariga, S.B. Halligudi, A. Vinu, Adv. Funct. Mater., in press]. The catalysts have been unambiguously characterized by XRD, N₂ adsorption, and TPD of NH₃, and utilized for the acetylation of veratrole, and other aromatic substrates such as anisole, isobutylbenzene, and 2-methoxynaphthalene, using acetic anhydride (AA) as an acylating agent under liquid phase conditions. The effect of various parameters such as the reaction temperature, reaction time, reactant mole ratios, and amount of aluminium, on the AA conversion in the acetylation of veratrole has been investigated in detail to discover the optimized reaction condition. The reaction conditions were optimized to get more conversion of acetic anhydride and the activity of these catalysts has been compared with zeolite catalysts namely HY, Hβ, H-mordenite, and HZSM-5 zeolites, and the results are discussed in detail. It has been found that the AlKIT-5 catalysts showed excellent performance in the acetylation of veratrole over zeolites and other mesoporous catalysts studied under the optimized reaction conditions. Among the catalysts studied, AlKIT-5(10) was found to be the best catalyst, showing high conversion of AA and very high selectivity to the desired products. The conversion of AA decreases in the following order: AlKIT-5(10) > AlKIT-5(28) > HY(13.5) > Hβ(30) > AlKIT-5(44) > AlMCM-41(22) > H-mordenite(20) > ZSM-5(60). Moreover, the kinetics of the AlKIT-5(10) catalyst in the acetylation of veratrole has been investigated in detail and the results are clearly discussed.     

Epigenetic effects of environmental chemicals bisphenol a and phthalates

The epigenetic effects on DNA methylation, histone modification, and expression of non-coding RNAs (including microRNAs) of environmental chemicals such as bisphenol A (BPA) and phthalates have expanded our understanding of the etiology of human complex diseases such as cancers and diabetes. Multiple lines of evidence from in vitro and in vivo models have established that epigenetic modifications caused by in utero exposure to environmental toxicants can induce alterations in gene expression that may persist throughout life. Epigenetics is an important mechanism in the ability of environmental chemicals to influence health and disease, and BPA and phthalates are epigenetically toxic. The epigenetic effect of BPA was clearly demonstrated in viable yellow mice by decreasing CpG methylation upstream of the Agouti gene, and the hypomethylating effect of BPA was prevented by maternal dietary supplementation with a methyl donor like folic acid or the phytoestrogen genistein. Histone H3 was found to be trimethylated at lysine 27 by BPA effect on EZH2 in a human breast cancer cell line and mice. BPA exposure of human placental cell lines has been shown to alter microRNA expression levels, and specifically, miR-146a was strongly induced by BPA treatment. In human breast cancer MCF7 cells, treatment with the phthalate BBP led to demethylation of estrogen receptor (ESR1) promoter-associated CpG islands, indicating that altered ESR1 mRNA expression by BBP is due to aberrant DNA methylation. Maternal exposure to phthalate DEHP was also shown to increase DNA methylation and expression levels of DNA methyltransferases in mouse testis. Further, some epigenetic effects of BPA and phthalates in female rats were found to be transgenerational. Finally, the available new technologies for global analysis of epigenetic alterations will provide insight into the extent and patterns of alterations between human normal and diseased tissues. In vitro models such as human embryonic stem cells may be extremely useful in bettering the understanding of epigenetic effects on human development, health and disease, because the formation of embryoid bodies in vitro is very similar to the early stage of embryogenesis.     

Alcohol use trajectories and the ubiquitous cat's cradle: Cause for concern?

[Correction Notice: An erratum for this article was reported in Vol 120(2) of Journal of Abnormal Psychology (see record 2011-05801-001). Due to formatting problems, some of the data and graphic information in the original Figure 7 are not correctly displayed. Although not all data in the original Figure 7 are visible, nothing displayed in that figure was in error.] In recent years, trajectory approaches to characterizing individual differences in the onset and course of substance involvement have gained popularity. Previous studies have sometimes reported 4 prototypic courses: (a) a consistently “low” group, (b) an “increase” group, (c) a “decrease” group, and (d) a consistently “high” group. Although not always recovered, these trajectories are often found, despite these studies varying in the ages of the samples studied and the duration of the observation periods employed. Here, the authors examined the consistency with which these longitudinal patterns of heavy drinking were recovered in a series of latent class growth analyses that systematically varied the age of the sample at baseline, the duration of observation, and the number and frequency of measurement occasions. Data were drawn from a 4-year, 8-wave panel study of college student drinking (N = 3,720). Despite some variability across analyses, there was a strong tendency for these prototypes to emerge regardless of the participants' age at baseline and the duration of observation. These findings highlight potential problems with commonly employed trajectory-based approaches and the need to not over-reify these constructs. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Rheology of milk foams produced by steam injection

Abstract: Rheology of milk foams generated by steam injection was studied during the transient destabilization process using steady flow and dynamic oscillatory techniques: yield stress (τ_y) values were obtained from a stress ramp (0.2 to 25 Pa) and from strain amplitude sweep (0.001 to 3 at 1 Hz of frequency); elastic (G′) and viscous (G″) moduli were measured by frequency sweep (0.1 to 10 Hz at 0.05 of strain); and the apparent viscosity (η_a) was obtained from the flow curves generated from the stress ramp. The effect of plate roughness and the sweep time on τ_y was also assessed. Yield stress was found to increase with plate roughness whereas it decreased with the sweep time. The values of yield stress and moduli—G′ and G″—increased during foam destabilization as a consequence of the changes in foam properties, especially the gas volume fraction, ?, and bubble size, R₃₂ (Sauter mean bubble radius). Thus, a relationship between τ_y, ?, R₃₂, and σ(surface tension) was established. The changes in the apparent viscosity, η, showed that the foams behaved like a shear thinning fluid beyond the yield point, fitting the modified Cross model with the relaxation time parameter (λ) also depending on the gas volume fraction. Overall, it was concluded that the viscoelastic behavior of the foam below the yield point and liquid‐like behavior thereafter both vary during destabilization due to changes in the foam characteristics. Practical Application: Studying the transient rheology of milk foams during destabilization contributes to our knowledge of the relationships between the changes in foam properties: texture and mouth feel during the consumption of hot foamed beverages.     

Reasons for abstaining or limiting drinking: A developmental perspective.

The cross-sectional and longitudinal relations between reasons for abstaining or limiting drinking (RALD) and abstention were examined in a 16-year longitudinal study (N = 489) of college students with and without a family history of alcohol problems. Results indicated that RALD based upon upbringing or religiosity were associated with increased rates of abstention, whereas RALD based upon perceived or experienced negative consequences of drinking were associated with lower rates of abstention and increased alcohol consumption among drinkers. In addition, changes in RALD over time coincided with alcohol consumption transitions. Abstainers who began drinking after turning 21 reported a decrease in the importance of RALD associated with loss of control and upbringing or religiosity compared to abstainers who continued to abstain after turning 21. Conversely, drinkers who began abstaining after leaving college reported an increase in the importance of RALD associated with loss of control and upbringing or religiosity compared to drinkers who continued to drink after leaving college. Examining the reciprocal influences of RALD on drinking outcomes extends previous research and may inform prevention and intervention programs among college drinkers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of viscosity of partings in block-hierarchical media on propagation of low-frequency pendulum waves

The study focuses on the pendulum-type wave propagation in an assembly of steel rods parted alternatively by rubber and foam plastic and exposed to impulse loading. The proposed numerical model describes this system as a chain of masses linked by elastic springs and viscous damping elements. At large times from the loading onset, the asymptotical estimates of velocities and accelerations of the masses are obtained. The numerical calculations, analytical solutions and experimental data are compared, and the domain of applicability of the analytical evaluations is delimited. The authors show that this model adequately describes perturbations in the system of rods with alternating visco-elastic partings. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 3–13, May–June, 2008.     

Clinical relevance of heavy drinking during the college years: Cross-sectional and prospective perspectives.

This study investigated the clinical relevance of heavy drinking during the college years and beyond on concurrent and prospective alcohol-related problems in a high-risk sample (N?=?377). Measures of heavy drinking and alcohol-related problems were significantly correlated cross-sectionally over the study frame, regardless of how these constructs were operationalized. However, the magnitude of the association between heavy drinking and alcohol-related problems declined substantially over time, with the most pronounced decrease following the college years. Despite this cross-sectional decrease in the association between heavy drinking and alcohol-related problems over time, heavy drinking during the college years significantly and substantially predicted alcohol-use disorders up to 10 years later. Implications for assessment of heavy drinking as well as prevention of problematic alcohol use in college students are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personality and substance use disorders: A prospective study.

The personality systems of Cloninger (as measured by the Tridimensional Personality Questionnaire [TPQ]) and Eysenck (as measured by the Eysenck Personality Questionnaire [EPQ]) both have been linked to substance use and abuse. The current study examined the predictive utility of both systems for substance use disorder (SUD) diagnoses, both cross-sectionally and prospectively. Participants (N?=?489 at baseline) completed the EPQ and TPQ and were assessed via structured diagnostic interview at baseline and 6 years later (N?=?457 at follow-up). Both the EPQ and TPQ scales demonstrated bivariate cross-sectional and prospective associations with SUDs. Within each system, those dimensions marking a broad impulsive sensation-seeking or behavioral disinhibition trait were the best predictors prospectively, although the 2 systems were differentially sensitive to specific diagnoses. These relations remained significant even with autoregressivity, other concurrent SUD diagnoses, and multiple personality dimensions statistically controlled. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic modeling of a gas pressure control system for a gas‐assisted injection molding process

This study presents the development of dynamic models for gas injection pressure that may be implemented in the design of control systems for gas‐injection units. A nonlinear dynamic model was first derived and then verified by experimental measurements. This was done by using a laboratory‐built, gas‐assisted injection unit. The agreement between the prediction and measurement indicates that the present nonlinear dynamic model adequately predicts the dynamic behavior of gas injection pressure during the process. Although the resulting model is useful for understanding the behavior of the process and the effects of different process variables, its complexity may cause difficulties in a real control application. Therefore, a second‐order model based on the basic characteristics of the nonlinear model was proposed to approximate the gas injection pressure. In order to determine the model parameters, the algorithm of recursive least‐square system identification was employed. A comparison of simulated results of an identified model with experimental data showed that the model accurately predicted the transient behavior of gas injection pressure. Consequently, this low‐order model can be easily implemented into the control system design of a gas‐injection unit.