Role of Diadegma semiclausum (Hymenoptera: Ichneumonidae) in controlling Plutella xylostella (Lepidoptera: Plutellidae): Cage exclusion experiments and direct observation

We evaluated the role of the larval parasitoid, Diadegma semiclausum Hellen (Hymenoptera: Ichneumonidae), in controlling Plutella xylostella (L.) (Lepidoptera: Plutellidae) by cage exclusion experiments and direct field observation during the winter season in southern Queensland, Australia. The cage exclusion experiment involved uncaged, open cage and closed cage treatments. A higher percentage (54-83%) of P. xylostella larvae on sentinel plants were lost in the uncaged treatment than the closed (4-9%) or open cage treatments (11-29%). Of the larvae that remained in the uncaged treatment, 72-94% were parasitized by D. semiclausum , much higher than that in the open cage treatment (8-37% in first trial, and 38-63% in second trial). Direct observations showed a significant aggregation response of the field D. semiclausum populations to high host density plants in an experimental plot and to high host density plots that were artificially set-up near to the parasitoid source fields. The degree of aggregation varied in response to habitat quality of the parasitoid source field and scales of the manipulated host patches. As a result, density-dependence in the pattern of parasitism may depend on the relative degree of aggregation of the parasitoid population at a particular scale. A high degree of aggregation seems to be necessary to generate density-dependent parasitism by D. semiclausum . Integration of the cage exclusion experiment and direct observation demonstrated the active and dominant role of this parasitoid in controlling P. xylostella in the winter season. A biologically based IPM strategy, which incorporates the use of D. semiclausum with Bt, is suggested for the management of P. xylostella in seasons or regions with a mild temperature.

Direct observation of covalent adducts with Cys34 of human serum albumin using mass spectrometry

The interactions of the unpaired thiol residue (Cys34) of human serum albumin (HSA) with low-molecular-weight thiols and an Au(I)-based antiarthritic drug have been examined using electrospray ionization mass spectrometry. Early measurements of the amount of HSA containing Cys34 as the free thiol suggested that up to 30% of circulating HSA bound cysteine as a mixed disulfide. It has also been suggested that reaction of HSA with cysteine, occurs only on handling and storage of plasma. In our experiments, there were three components of HSA in freshly collected plasma from normal volunteers, HSA, HSA + cysteine, and HSA + glucose in the ratio similar to50:25:25. We addressed this controversy by using iodoacetamide to block the free thiol of HSA in fresh plasma, preventing its reaction with plasma cysteine. When iodoacetamide was injected into a vacutaner tube as blood was collected, the HSA was modified by iodoacetamide, with 20-30% present as the mixed disulfide with cysteine (HSA + cys). These data provide strong evidence that 20-30% of HSA in normal plasma contains one bound cysteine. Reaction of HSA with [Au(S2O3)(2)](3-) resulted in formation of the adducts HSA + Au(S2O3) and HSA + Au. Reaction of HSA with iodoacetamide prior to treatment with [Au(S2O3)(2)](3-) blocked the formation of gold adducts. (C) 2003 Elsevier Inc. All rights reserved.

Direct observation of mixed-parity excited states in surface-passivated PbS nanocrystals

Photoluminescent emission is observed from surface-passivated PbS nanocrystals following the two-photon excitation of high-energy excitonic states. The emission appears directly at the excitation energy with no detectable Stokes-shift for a wide range of excitation energies. The observation of direct emission from states excited by two-photon absorption indicates that the parity of the excited states of surface-passivated PbS nanocrystals is partially mixed.

Observation of crack initiation during hot tearing

While the general mechanisms of hot tearing are understood, i.e. the inability of liquid to feed imposed strain on the mushy material, work continues on improving the understanding of the mechanisms at play. A hot tear test rig that measures the temperature and load imposed on the mushy zone during solidification has been successfully used to study hot tearing. The mould has now been modified to incorporate a window above the hot spot region to allow observation of hot tear formation and growth. Combining information from visual observation with load and temperature data has led to a better understanding of the mechanism of hot tearing. Tests were carried out on an Al-0.5 wt-% Cu alloy. It was found that load development began at about 90% solid and a hot tear formed a short time later, at between 93% and 96% solid. Hot tearing started at a very low load.

The development of an observation tool for use with parents with psychiatric disability and their preschool children

Community-based treatment and care of people with psychiatric disabilities has meant that they are now more likely to engage in the parenting role. This has led to the development of programs designed to enhance the parenting skills of people with psychiatric disabilities. Evaluation of these programs has been hampered by a paucity of evaluation tools. This study's aim was to develop and trial a tool that examined the parent-child interaction within a group setting, was functional and easy to use, required minimum training and equipment, and had acceptable levels of reliability and validity. The revised tool yielded a single scale with acceptable reliability. It had discriminative validity and concurrent validity with non-independent global ratings of parenting. Sensitivity to change was not investigated. The findings suggest that this method of evaluating parenting is likely to have both clinical and research utility and further investigation of the psychometric properties of the tool is warranted.

In situ observation of bainite growth during isothermal holding

The mechanism of bainite growth has been investigated using in situ transmission electron microscopy observations. It was found that, in a number of alloys studied, a bainitic embryo is made of basic transformation units. These units are either a group of stacking faults or, in two dimensions, a series of parallelograms of different sizes. Thickening/widening of the bainite embryo takes place through shear along the stacking fault planes or twining planes. The bainite embryo is elongated by the formation of new transformation units at both tips of the bainite plate. The three-dimensional morphology of bainite is a convex tens-like lath. It is believed that the bainite embryo grows by shearing, which is controlled by the diffusion of solute atoms during the transformation. As the growth rate is much lower than that of martensite, it is therefore detectable. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis and spectroscopic observation of dendrimer-encapsulated gold nanoclusters

We report on the observation of the excitation/ emission spectrum of a dendrimer-encapsulated gold nanocluster; the synthesis of Au-PAMAM was based on reduction of HAuCl4 center dot 3H(2)O co-dissolved in methanol together with fourth-generation OH-terminated PAMAM.