An investigation of the effect of powder on the impact characteristics between a ball and a plate using free falling experiments

The study of the mechanisms of mechanical alloying requires knowledge of the impact characteristics between the ball and vial in the presence of milling powders. In this paper, foe falling experiments have br cn used to investigate the characteristics of impact events involved in mechanical milling. The effects of milling conditions, including impact velocity, ball size and powder thickness. on the coefficient of restitution and impact force are studied. It is found that the powder has a significant influence on the impact process due to its porous structure. This effect can be demonstrated using a modified Kelvin model. This study also confirms that the impact force is a relevant parameter for characterising the impact event due to its sensitivity to the milling conditions. (C) 1998 Elsevier Science S.A.

A conformationally sensitive GHR [growth hormone (GH) receptor] antibody: Impact on GH signaling and GHR proteolysis

The GH receptor (GHR) mediates metabolic and somatogenic actions of GH. Its extracellular domain (ECD; residues 1-246) has two subdomains, each with seven beta strands organized into two antiparallel beta sheets, connected by a short hinge region. Most of the ECD residues involved in GH binding reside in subdomain 1, whereas subdomain 2 harbors a dimerization interface between GHR dimers that alters conformation in response to GH. A regulated GHR metalloprotease cleavage site is in the membrane-proximal stem region of subdomain 2. We have identified a monoclonal anti-ECD antibody, anti-GHR(ext-mAb), which recognizes the rabbit and human GHRs by immunoprecipitation, but less so after GH treatment. By immunoblotting and immunoprecipitation, anti-GHR(ext-mAb) recognized a glutathione-S-transferase (GST) fusion incorporating subdomain 2, but not one including subdomain 1. In transient transfection experiments, anti-GHR(ext-mAb) failed to recognize by immunoprecipitation a previously characterized dimerization interface mutant GHR that is incompetent for signaling. In signaling experiments, brief pretreatment of GH-responsive human fibrosarcoma cells with anti-GHR(ext-mAb) dramatically inhibited GH-induced Janus kinase 2 and signal transducer and activator of transcription 5 tyrosine phosphorylation and prevented GH-induced GHR disulfide linkage (a reflection of GH-induced conformational changes). In contrast, anti-GHR(ext-mAb) only partially inhibited radiolabeled GH binding, suggesting its effects on signaling were not simply via inhibition of binding. Furthermore, anti-GHR(ext-mAb) prevented phorbol ester-stimulated GHR proteolysis, but GHR cleavage site mutants were normally recognized by the antibody, indicating that the stem region cleavage site is not a direct epitope. A Fab fragment of anti-GHR(ext-mAb) inhibited GH-induced GHR disulfide linkage and signaling, as well as phorbol ester-induced GHR proteolysis, in a fashion similar to the intact antibody. Thus, our findings suggest that anti-GHR(ext-mAb) has promise as a GH antagonist and as a tool in studies of conformational changes required for GHR activation.

Segmented polyurethane nanocomposites: Impact of controlled particle size nanofillers on the morphological response to uniaxial deformation

A series of TPU nanocomposites were prepared by incorporating organically modified layered silicates with controlled particle size. To our knowledge, this is the first study into the effects of layered silicate diameter in polymer nanocomposites utilizing the same mineral for each size fraction. The tensile properties of these materials were found to be highly dependent upon the size of the layered silicates. A decrease in disk diameter was associated with a sharp upturn in the stress-strain curve and a pronounced increase in tensile strength. Results from SAXS/SANS experiments showed that the layered silicates did not affect the bulk TPU microphase structure and the morphological response of the host TPU to deformation or promote/hinder strain-induced soft segment crystallization. The improved tensile properties of the nanocomposites containing the smaller nanofillers resulted from the layered silicates aligning in the direction of strain and interacting with the TPU sequences via secondary bonding. This phenomenon contributes predominantly above 400% strain once the microdomain architecture has largely been disassembled. Large tactoids that are unable to align in the strain direction lead to concentrated tensile stresses between the polymer and filler, instead of desirable shear stresses, resulting in void formation and reduced tensile properties. In severe cases, such as that observed for the composite containing the largest silicate, these voids manifest visually as stress whitening.

The impact of individualist and collectivist group norms on evaluations of dissenting group members

Two experiments were conducted to investigate the impact of individualist and collectivist norms on evaluations of dissenting group members. In the first experiment (N = 113), group norms prescribing individualism or collectivism were manipulated and participants were asked to evaluate a group member who expressed an attitude dissenting from or concordant with the group. In line with predictions, group members with concordant attitudes were evaluated more positively than group members with dissenting attitudes when norms prescribed collectivism. However, for high identifiers, we found an attenuation of the preference for Concordant over dissenting attitudes when norms prescribed individualism. These findings were replicated in a second experiment (N= 87), where dissent was operationalized in a way that did not reveal the content of the attitude. The discussion focused on the importance of individualist norms for broadening latitudes of acceptable group member behavior. (c) 2005 Elsevier Inc. All rights reserved.

Morphosyntactic and syntactic priming: an investigation of underlying processing mechanisms and the effects of Parkinson’s disease

There is now considerable evidence to suggest that non-demented people with Parkinson's disease (PD) experience difficulties using the morphosyntactic aspects of language. It remains unclear, however, at precisely which point in the processing of morphosyntax, these difficulties emerge. The major objective of the present study was to examine the impact of PD on the processes involved in accessing morphosyntactic information in the lexicon. Nineteen people with PD and 19 matched control subjects participated in the study which employed on-line word recognition tasks to examine morphosyntactic priming for local grammatical dependencies that occur both within (e.g. is going) and across (e.g. she gives) phrasal boundaries (Experiments 1 and 2, respectively). The control group evidenced robust morphosyntactic priming effects that were consistent with the involvement of both pre- (Experiment 1) and post-lexical (Experiment 2) processing routines. Whilst the participants with PD also recorded priming for dependencies within phrasal boundaries (Experiment 1), priming effects were observed over an abnormally brief time course. Further, in contrast to the controls, the PD group failed to record morphosyntactic priming for constructions that crossed phrasal boundaries (Experiment 2). The results demonstrate that attentionally mediated mechanisms operating at both the pre- and post-lexical stages of processing are able to contribute to morphosyntactic priming effects. In addition, the findings support the notion that, whilst people with PD are able to access morphosyntactic information in a normal manner, the time frame in which this information remains available for processing is altered. Deficits may also be experienced at the post-lexical integrational stage of processing.

From Midden to Sieve: The Impact of Differential Recovery and Quantification Techniques on Interpretations of Shellfish Remains in Australian Coastal Archaeology

Experimental mechanical sieving methods are applied to samples of shellfish remains from three sites in southeast Queensland, Seven Mile Creek Mound, Sandstone Point and One-Tree, to test the efficacy of various recovery and quantification procedures commonly applied to shellfish assemblages in Australia. There has been considerable debate regarding the most appropriate sieve sizes and quantification methods that should be applied in the recovery of vertebrate faunal remains. Few studies, however, have addressed the impact of recovery and quantification methods on the interpretation of invertebrates, specifically shellfish remains. In this study, five shellfish taxa representing four bivalves (Anadara trapezia, Trichomya hirsutus, Saccostrea glomerata, Donax deltoides) and one gastropod (Pyrazus ebeninus) common in eastern Australian midden assemblages are sieved through 10mm, 6.3mm and 3.15mm mesh. Results are quantified using MNI, NISP and weight. Analyses indicate that different structural properties and pre- and postdepositional factors affect recovery rates. Fragile taxa (T. hirsutus) or those with foliated structure (S. glomerata) tend to be overrepresented by NISP measures in smaller sieve fractions, while more robust taxa (A. trapezia and P. ebeninus) tend to be overrepresented by weight measures. Results demonstrate that for all quantification methods tested a 3mm sieve should be used on all sites to allow for regional comparability and to effectively collect all available information about the shellfish remains.

Research Quality, Publications and Impact in Hydraulic Engineering into the 21st Century. Publish or Perish, Commercial versus Open Access, Internet versus Libraries

One of the main objectives of the first International Junior Researcher and Engineer Workshop on Hydraulic Structures is to provide an opportunity for young researchers and engineers to present their research. But a research project is only completed when it has been published and shared with the community. Referees and peer experts play an important role to control the research quality. While some new electronic tools provide further means to disseminate some research information, the quality and impact of the works remain linked with some thorough expert-review process and the publications in international scientific journals and books. Importantly unethical publishing standards are not acceptable and cheating is despicable.

A simple data logger for student-designed rocket experiments.

The final-year project for Mechanical & Space Engineering students at UQ often involves the design and flight testing of an experiment. This report describes the design and use of a simple data logger that should be suitable for collecting data from the students' flight experiments. The exercise here was taken as far as the construction of a prototype device that is suitable for ground-based testing, say, the static firing of a hybrid rocket motor.

Impact of Commercial Search Engines and International Databases on Engineering Teaching and Research

For the last three decades, the engineering higher education and professional environments have been completely transformed by the "electronic/digital information revolution" that has included the introduction of personal computer, the development of email and world wide web, and broadband Internet connections at home. Herein the writer compares the performances of several digital tools with traditional library resources. While new specialised search engines and open access digital repositories may fill a gap between conventional search engines and traditional references, these should be not be confused with real libraries and international scientific databases that encompass textbooks and peer-reviewed scholarly works. An absence of listing in some Internet search listings, databases and repositories is not an indication of standing. Researchers, engineers and academics should remember these key differences in assessing the quality of bibliographic "research" based solely upon Internet searches.

Information and wildlife valuation: Experiments and policy

The authors use experimental surveys to investigate the association between individuals' knowledge of particular wildlife species and their stated willingness to allocate funds to conserve each. The nature of variations in these allocations between species (e.g., their dispersion) as participants' knowledge increases is examined. Factors influencing these changes are suggested. Willingness-to-pay allocations are found not to measure the economic value of species, but are shown to be policy relevant. The results indicate that poorly known species, e.g., in remote areas, may obtain relatively less conservation support than they deserve.