56 resultados para Sintered samples

em Deakin Research Online - Australia


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This study examined whether age, gender, intelligence, communication ability and shyness predict intellectually disabled children’s susceptibility to an interviewer’s misleading suggestions. Further, the study examined whether the relative influence of these factors differs between intellectually disabled and mainstream samples. Participants included 75 children with mild and borderline intellectual disabilities (aged 77–158 months) and 83 mainstream children (aged 68–152 months). All children were individually administered the Yield and Shift subscales of the Gudjonsson Suggestibility Scale (Form 2) as well as standardised measures of IQ, shyness and communication ability. For the intellectually disabled children, multiple regression analyses revealed that age, IQ and communication inversely predicted Yield suggestibility, however, none of the factors predicted Shift suggestibility. For the mainstream children, age made a significant independent contribution to both Yield and Shift suggestibility, while IQ was a significant predictor of Shift suggestibility. When comparing the relative impact of these factors across the samples, age had a significantly greater impact on mainstream (compared with intellectually disabled) children’s Shift suggestibility, while IQ had a significantly greater influence on intellectually disabled (compared with mainstream) children’s Yield scores. These findings highlight the limited generalisability of previous findings involving mainstream children’s suggestibility to intellectually disabled samples.


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For some research projects, recruiting in public places is an invaluable addition to sampling strategies. It complements the more traditional recruitment strategies by providing researchers with' opportunities to include people in the research who would otherwise be excluded. One of the limitations of selective and snowball sampling is that participants often come from the same social group. Participants from these social groups often share similar experiences and ways of thinking about those experiences. The aim of recruiting in public places is to move beyond this 'in group' to ensure a wider perspective. This paper illustrates how recruiting in public places can provide greater sample diversity for theoretical strength. The paper begins with a brief overview of recruiting in public places. It then describes the theoretical considerations associated with this recruiting strategy. The paper demonstrates how recruiting in public places facilitates grounded theory by providing comparisons that are informed by diverse experiences. Using examples and a case study, we illustrate how recruiting in public places can complement selective, snowball and theoretical sampling to ensure a more comprehensive sample.

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The mono-isopropylamine salt of glyphosate was selectively determined directly in industrial and commercial formulations using flow injection analysis with tris(2,2′-bipyridyl)ruthenium(II) chemiluminescence detection without the need for separation. Glyphosate and its mono-isopropylamine salt furnished detection limits of 7×10−9 and 3.5×10−10 M and relative standard deviations of 0.4% at 1×10−7 M and 0.8% at 5×10−8 M, respectively. The methodology is robust and reliable with samples subjected only to aqueous dilution prior to analysis.

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Although the dominant methods for the determination of urea in clinical applications incorporate selective enzymatic hydrolysis of urea, the determination of urea in soil extracts is complicated by the presence of urease inhibitors. The spectrophotometric determination of urea with an acidic solution diacetyl monoxime and semicarbazide is a viable option but traditional manual procedures are time-consuming. New variations on these procedures, based on microplates or flow-injection analysis methodologies, allow a far greater number of samples to be analysed with high precision and sensitivity.

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Although youth drug and alcohol harm minimization policies in Australia are often contrasted with the abstinence and zero tolerance policies adopted in the United States, there has been little research directly comparing youth substance use behaviour in the two countries. Three state representative samples in Victoria, Australia (n = 7898) and in the US states of Oregon (n = 15 224) and Maine (n = 16 245) completed a common cross-sectional student survey. Rates of alcohol use (lifetime alcohol use, recent use in the past 30 days), alcohol use exceeding recommended consumption limits (binge drinking: five or more drinks in a session), other licit drug use (tobacco use), and norm-violating substance use (substance use at school, use in the past 30 days of marijuana or other illicit drug use) were compared for males and females at ages 12-17. Rates were lower (odds ratios 0.5-0.8) for youth in Maine and Oregon compared to Victoria for lifetime and recent alcohol use, binge drinking and daily cigarette smoking. However, rates of recent marijuana use and recent use of other illicit drugs were higher in Maine and Oregon, as were reports of being drunk or high at school. In contradiction of harm minimization objectives, Victoria, relative to the US states of Oregon and Maine, demonstrated higher rates of alcohol use exceeding recommended consumption limits and daily tobacco use. However, findings suggested that aspects of norm-violating substance use (substance use at school, marijuana use and other illicit drug use) were higher in the US states compared to Victoria.

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In the present study, Ti-16Sn-4Nb alloy was prepared by mechanical alloying (MA). Optical microscopy, scanning electron microscopy combined with energy dispersive X-ray analysis (SEM-EDX), and X-ray diffraction analysis (XRD) were used to characterise the phase transformation and the microstructure evolution. Results indicated that ball milling to 8 h led to the formation of a supersaturated hcp α-Ti and partial amorphous phase due to the solid solution of Sn and Nb into Ti lattice. The microstructure of the bulk sintered Ti-16Sn-4Nb alloy samples made from the powders at shorter ball milling times, i.e. 20 min- 2 h, exhibited a primary α surrounded by a Widmanstätten structure (transformed β); while in the samples made from the powders at longer ball milling times, i.e. 5- 10 h, the alloy evolved to a microstructure with a disordered and fine β phase dispersed homogeneously within the α matrix. These results contribute to the understanding of the microstructure evolution in alloys of this type prepared by powder metallurgy.

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The purpose of this paper is to describe a process for sampling specific domain name zones on the World Wide Web. Because of the size of the Web, sampling strategies must be employed in order to effectively model and study the Web business environment.  This paper discusses Various efforts employed to sample the Web, which ranged from random generation of Internet Protocol Addresses and domain names, to the process finally
employed to create descriptive models of the dot-com domain name zones. The paper suggests that sampling the Web Top Level Domains offers a reasonable alternative for business researchers because it requires only familiarity with the use of the simple Web utilities such as File Transfer
Protocols to obtain initial domain name listings.

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Air-atomized pure aluminium powder with 15 at.% MgB2 was mechanically milled (MMed) by using a vibrational ball mill, and MMed powders were consolidated by spark plasma sintering (SPS) to produce composite materials with high specific strength. Solid-state reactions of MMed powders have been examined by X-ray diffraction (XRD), and mechanical properties of the SPSed materials have been evaluated by hardness measurements and compression tests. Orientation images of microstructures were obtained via the electron backscatter diffraction (EBSD) technique.

The solid-state reactions in the Al–15 at.% MgB2 composite materials occurred between the MMed powders and process control agent (PCA) after heating at 773–873 K for 24 h. The products of the solid-state reaction were a combination of AlB2, Al3BC and spinel MgAl2O4. Mechanical milling (MM) processing time and heating temperatures affect the characteristics of those intermetallic compounds. As the result of the solid-state reactions in MMed powders, a hardness increase was observed in MMed powders after heating at 573–873 K for 24 h. The full density was attained for the SPSed materials from 4 h or 8 h MMed powders in the Al–15 at.% MgB2 composite materials under an applied pressure of 49 MPa at 873 K for 1 h. The microstructure of the SPSed materials fabricated from the MMed powders presented the bimodal aluminium matrix grain structure with the randomly distributions. The Al–15 at.% MgB2SPSed material from powder MMed for 8 h exhibited the highest compressive 0.2% proof strength of 846 MPa at room temperature.

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In the present study, the influence of process control agent (PCA) on the characteristics of powder and bulk sintered Ti-16Sn-4Nb (wt. %) alloy prepared by mechanical alloying has been investigated. The elemental Ti, Sn and Nb powders were mechanically alloyed in a planetary ball mill for a short period of time using two types of PCA, namely stearic acid (SA) and ethylene bis-stearamide (EBS). The powder morphology, microstructural evolution of the bulk sintered alloy, phase formation and hardness of the alloy have been studied as a function of PCA. Results indicated that the addition of PCA leads to a delay in aIloy formation and introduces contaminations (mainly carbon and oxygen) into the material. The microstructural observation of the bulk alloy revealed a homogeneous distribution of fine Nb-rich colonies (ß-phase) within the a-Ti matrix for small amount of PCA. The hardness values of samples exhibited a significant increase with increasing amount of PCA, reaching a value of ~ 600 BV.

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This phenomenological study of the meaning of home from the perspectives of people with and without an intellectual disability sought to identify, (a) any common ‘essence’ of meaning held by and, (b) the nature of any differences of perception between, the groups. Purposive samples of 18 people with an intellectual disability and 21 non-disabled people were surveyed using a semi-structured interview to ascertain their experiences of home and 'non-homes'. Inductive analysis of the data revealed a shared understanding of the meaning of home at a fundamental level. This shared meaning of home was found to comprise: the ability to exert control over an area; having a personalised space; feeling content with the living situation; a sense of familiarity with the setting; a set of behaviours and routines usually only enacted when at home; common names and uses for rooms; socialising at home with others; the importance of a positive social atmosphere in the home; and, recognition of places as non-homes because they lacked one or more of these attributes. Further analysis revealed the essence of home is its experience as the place where stress is most reduced or minimised for the individual. The study demonstrates that the concept of stress is superordinate to previously identified concepts considered fundamental to home such as privacy, control and non-homes. Major differences between the two samples were largely differences of degree with people who have an intellectual disability reporting the same fundamental attributes of home as people who do not have an intellectual disability, but in a less elaborated form. Principal among these differences of degree was the notion of control over the home and its derivative elements which encompassed the whole dwelling including its setting for people without an intellectual disability but was very restricted for people with an intellectual disability being largely confined to the person's bedroom. Socialising in or from the home was also very limited for people with an intellectual disability in comparison with that experienced by non-disabled informants with the former group conveying an impression of leading significantly socially isolated lives at home. The major implications of this study are related to the meaning of home per se, to residential service provision to people with an intellectual disability, and to future research.

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The aluminium-rich ternary aluminium borocarbide, Al3BC was synthesised for the first time by solid-state reactions occurring during heat treatments after mechanical milling (MM) of pure aluminium with 15 or 50 at% MgB2 powder mixtures in the presence of the process control agent (PCA).

The solid-state reactions in the Al–15 and 50 at% MgB2 composite materials occurred between the MMed powders and process control agent (PCA) after heating at 773–873 K for 24 h. The products of the solid-state reaction induced Al3BC, AlB2, γ-Al2O3 and spinel MgAl2O4. MM processing time and heating temperatures in the Al–15 and 50 at% MgB2 composite materials affected the selection of those intermetallic compounds. When MM processing time was increased for a given composition, the formation of the Al3BC compound started at lower heat treatment temperatures. However, when the amount of MgB2 was increased in the 4 h MM processing regime, the formation of the Al3BC compound during heating was suppressed. As a result of the solid-state reactions in MMed powders the hardness was observed to increase after heating at 573–873 K for 24 h.

The fully dense bulk nano-composite materials have been successfully obtained through the combination of the MM and spark plasma sintering (SPS) processes for the 4 h or 8 h MMed powders of the Al–15 at% MgB2 composite materials sintered under an applied pressure of 49 MPa at 873 K for 1 h.

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An improved post-column 2,2´-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging assay for the screening of antioxidants in complex matrices was developed. Experimental parameters believed to be influential to DPPH• response were studied in a univariate approach. Optimum conditions were found to be: 5×10−5M DPPH• reagent prepared in a 75% methanol: 25% 40mM citric acid–sodium citrate buffer (pH 6) solution, degassed with nitrogen; reaction coil of 2m×0.25mm i.d. PEEK tubing; detection at 521 nm; analysis at room temperature. The analytical utility of this protocol was evaluated by screening for antioxidants in thyme and green tea, in comparison with two commonly employed methodologies.