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Various fields such as mechanical engineering, materials science, etc., have seen a widespread use of linear elastic fracture mechanics (LEFM) at the continuum scale. LEFM is also routinely applied to the atomic scale. However, its applicability at this scale remains less well studied, with most studies focusing on non-linear elastic effects. Using a harmonic “snapping spring” nearest-neighbor potential which provides the closest match to LEFM on a discrete lattice, we show that the discrete nature of an atomic lattice leads to deviations from the LEFM displacement field during energy minimization. We propose that these deviations can be ascribed to geometrical nonlinearities since the material does not have a nonlinear elastic response prior to bond breaking. We demonstrate that crack advance and the critical stress intensity factor in an incremental loading scenario is governed by the collectively loaded region, and can not be determined analytically from the properties (max. elongation, max. sustained force, etc.) of the stressed crack tip bond alone.

The present investigation was carried out to compare the alterations of digestive enzymes like amylase, lipase, and protease activities in three teleostean fishes viz., Anabas testudineus, Heteropneustes fossilis and Oreochromis niloticus after application of almix herbicide for 30 days at rice field concentration i.e., 8 g/acre. Highest amylase activity was observed in intestine of A. testudineus (300.76%) and lowest in intestine of H. fossilis (103.89%), while maximum lipase activity was found in stomach of O. niloticus (203.27%) and lowest in stomach of H. fossilis (109.65%). Protease activity was also highest in liver of O. niloticus (270.47%) but lowest in stomach of H. fossilis (114.04%). Changes in the enzymes’ activity were different in respect to fishes and their tissues. According to this analysis, A. testudineus and O. niloticus were more sensitive. So, it can be inferred that long-term exposure of almix even at environment-friendly concentration may cause alterations in the digestive functions.

Though group interventions are widely used in community-based and clinical settings, there are few brief instruments for assessing the group environment. Two studies on the development of a brief measure to assess intervention group environments are described, and psychometric properties of the new scale are presented. The new measure is based on Moos' (1994) Group Environment Scale (GES). Participants in the studies were from two independent randomized controlled clinical trials (RCTs) of group interventions (combined N=334). In Study 1 (N=139), the factor content of the original 90-item GES was examined. The scale was shortened, the response format was changed, and items were adapted and added to in an effort to increase applicability to community-based and clinical intervention groups. In Study 2 (N=195), the new scale was evaluated, the factor solution obtained in Study 1 was cross-validated, and subsequently the length of the scale was shortened again. The final scale contains 25 items with three subscales. Reliability and validity of the new scale was examined. Finally, the research and practice implications of the scale are discussed. (Contains 4 tables, 2 footnotes and 1 figure.)

This study examined the longitudinal effects of coping on outcome one year following completion of a randomized, controlled trial of a group coping intervention for AIDS-related bereavement. Bereaved HIV-positive participants (N = 267) were administered measures of grief, psychiatric distress, quality of life, and coping at baseline, post-intervention, and at 4-, 8-, and 12-month follow-ups. Coping strategies directly impacted all outcome variables for both study conditions. Additionally, the coping intervention moderated the relationship between avoidant coping and the longitudinal course of grief and psychiatric distress, resulting in greater reductions in grief and distress for intervention participants after accounting for avoidant coping strategies. (Contains 4 tables and 1 figure.)

A qualitative study was conducted with 28 women who are human immunodeficiency virus (HIV)-positive and have experienced childhood sexual abuse (CSA) in order to examine (1) the challenges generated by the experience of sexual abuse and related coping strategies, (2) the impact of the HIV diagnosis on their coping strategies, and (3) the links perceived by the women between their CSA and HIV infection. The interviews revealed that CSA raised challenges in four areas: disclosure of the abuse, sexual problems, relationship difficulties, and psychological distress. The women used two strategies to cope with their CSA: illicit substances to numb their emotional distress and sexual activity, and alienation to gain control in relationships. When diagnosed with HIV, the women initially coped with their illness by using these two strategies. The women reported that, over time, they were able to accept their HIV illness, seek social support, find alternative sources of significance, and use spirituality to sustain their growth. However, they continued to suffer psychological distress related to their sexual trauma. Further, most of the women did not perceive any connection between the two traumas. Implications of these findings for secondary prevention interventions with women who have HIV and experience of CSA are discussed. (Contains 1 table.)

Examines religious practices of Hindus in the United States and develops measures of their religious pathways. Four religious pathways were identified: devotion, ethical action, knowledge, and physical restraint/yoga. Results indicate that the measures of the religious pathways possessed adequate psychometric properties and were predictive of mental and physical well-being. (Contains 46 references, 3 tables, and 1 appendix.) (GCP)

This study assessed the role of religion in the coping of 45 parents of children with autism. All parents completed a questionnaire and 21 parents were interviewed. Positive religious coping was associated with better religious outcome and greater stress-related growth, whereas negative religious coping was associated with greater depressive affect and poorer religious outcome. (Contains references.) (DB)

The dimers involving benzene or other substituted [pi] systems were investigated to examine the relevance of the magnitudes of their attractive and repulsive interaction energy components in governing the geometries of several [pi]-[pi] systems. The findings suggest that the presence of substituents on the aromatic ring, irrespective of their electron withdrawing or donating nature leads to an increase in the binding energy.

The structures of neutral and anionic gold-silver binary clusters and pure gold and silver clusters are investigated. It is shown that the calculated electronic properties and dissociation energy of both pure and binary clusters are in agreement with the available experimental data.

Research discusses the origin of the fast diffusion reactivity and the role of low activation barrier in the catalytic mechanism in the context of preorganization, short strong hydrogen bond, and the charge buffering/dissipation of the catalytic residues. Results show that the charge buffering by the catalytic residues reduces negative charge accumulation.

Research examines a new family of ionophores, [n]beltenes, which possess a cation-olefinic pi type interaction as opposed to [n]collarenes exhibiting cation-aromatic pi interaction. Data indicate that the [n]beltenes have binding affinities to metal cations and also show delicate ion selectivity properties.

The interactions of first-row hydrides with ethene and benzene are investigated with regard to olefinic vs aromatic pi-H interactions.

The authors review the publications on the weakly bound van der Waals complexes of pi-systems and their properties. The topics of interest include the theoretical methods, the salient results obtained from the ab initio calculations for different pi-complexes and the results obtained via empirical and semiempirical calculations for the larger pi-complexes.

This research focuses on a comparison of the electronic properties, vibrational frequencies, binding energies, and the geometries of the minimal energy conformers of the C6H6-AlX3 and the corresponding C2H4-AlX3 systems.

Research was conducted to predict the binding energies and geometries of benzene-BX3 and ethene-BX3 complexes using quantum mechanical ab initio calculations. Single point measurements at a much higher correlation level and larger basis sets were also performed. Results based on binding energies indicate that all the complexes were weakly bound van der Waals complexes except for the C2H4-BH3 complex. There was also a strong evidence of an unusual increase in the nucleophilicity of one of the benzene carbons in the lowest energy conformer of systems involving benzene.

A study was conducted to analyze the role of Lewis acid(AlCl3)-aromatic ring interactions in Friedel-Craft's reaction. High-level ab initio computations were carried out on two model systems. Findings showed unusual molecular orbital interactions during the ring interactions. Results also indicated that Lewis acid supports a critical role in the activation of the aromatic substrate prior to attack by the electrophile.

A new strategy for reversible hydrogen storage based on the properties of hydrogen multicenter bonds is proposed. This is demonstrated by carrying out ab initio calculations of hydrogen saturation of titanium and bimetallic titanium-aluminum nanoclusters. Hydrogen saturation leads to the formation of exceptionally and energetically stable hydrogen multicenter bonds. The stabilization results from sharing of the hydrogen atom electron density with the frontier orbitals of the metal cluster. The strength of the hydrogen multicenter bonds can be modulated either by varying the degree of hydrogen loading or by suitable alloying. Mode-specific infrared excitation of the vibrational modes associated with the multicenter hydrogen bonds can release the adsorbed hydrogen, thereby enabling efficient reversible hydrogen storage. The possible formation of hydrogen multicenter bonds involving titanium atoms and its implication to hydrogen adsorption/desorption kinetics in hydrogen cycled Ti-doped NaAlH4 is also discussed. [ABSTRACT FROM AUTHOR]