Flash Spark Plasma Sintering (FSPS) of Pure ZrB2

Export Date: 19 August 2014 CODEN: JACTA Correspondence Address: Reece, M.J.; School of Engineering and Material Science, Queen Mary University of London, London E1 4NS, United Kingdom; email: [email protected] Funding Details: EP/K008749/1, EPSRC, European Commission Funding Details: FP7 2007-2013, EC, European Commission References: Cologna, M., Rashkova, B., Raj, R., Flash Sintering of Nanograin Zirconia in <5 s at 850°C (2010) J. Am. Ceram. Soc., 93 (11), pp. 3556-3559; Downs, J.A., Sglavo, V.M., Electric Field Assisted Sintering of Cubic Zirconia at 390°C (2013) J. Am. Ceram. Soc., 96 (5), pp. 1342-1344; Muccillo, R., Muccillo, E.N.S., An Experimental Setup for Shrinkage Evaluation during Electric Field-Assisted Flash Sintering: Application to Yttria-Stabilized Zirconia (2013) J. Eur. Ceram. Soc., 33 (3), pp. 515-520; Muccillo, R., Muccillo, E.N.S., Electric Field-Assisted Flash Sintering of Tin Dioxide (2014) J. Eur. Ceram. Soc., 34 (4), pp. 915-923; Jha, S.K., Raj, R., The Effect of Electric Field on Sintering and Electrical Conductivity of Titania (2014) J. Am. Ceram. Soc., 97 (2), pp. 527-534; Zapata-Solvas, E., Bonilla, S., Wilshaw, P.R., Todd, R.I., Preliminary Investigation of Flash Sintering of SiC (2013) J. Eur. Ceram. Soc., 33 (1314), pp. 2811-2816; Grasso, S., Sakka, Y., Rendtorff, N., Hu, C., Maizza, G., Borodianska, H., Vasylkiv, O., Modeling of the Temperature Distribution of flash sintered Zirconia (2011) Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/J. Ceram. Soc. Jpn., 119 (1386), pp. 144-146; Park, J., Chen, I.W., In Situ Thermometry Measuring Temperature Flashes Exceeding 1,700°C in 8 mol% Y2O3-Stablized Zirconia under Constant-Voltage Heating (2013) J. Am. Ceram. Soc., 96 (3), pp. 697-700; Zapata-Solvas, E., Jayaseelan, D.D., Lin, H.T., Brown, P., Lee, W.E., Mechanical Properties of ZrB2- and HfB2-Based Ultra-High Temperature Ceramics Fabricated by Spark Plasma Sintering (2013) J. Eur. Ceram. Soc., 33 (7), pp. 1373-1386; Grasso, S., Sakka, Y., Maizza, G., Electric Current Activated/Assisted Sintering (ECAS): A Review of Patents 1906-2008 (2009) Sci. Technol. Adv. Mater., 10 (5), p. 053001; Mallik, M., Kailath, A.J., Ray, K.K., Mitra, R., Electrical and Thermophysical Properties of ZrB2 and HfB 2 Based Composites (2012) J. Eur. Ceram. Soc., 32 (10), pp. 2545-2555; Steil, M.C., Marinha, D., Aman, Y., Gomes, J.R.C., Kleitz, M., From Conventional Ac Flash-Sintering of YSZ to Hyper-Flash and Double Flash (2013) J. Eur. Ceram. Soc., 33 (11), pp. 2093-2101; Ortiz, A.L., Zamora, V., Rodríguez-Rojas, F., A Study of the Oxidation of ZrB2 Powders during High-Energy Ball-Milling in Air (2012) Ceram. Int., 38 (4), pp. 2857-2863; Porwal, H., Tatarko, P., Grasso, S., Hu, C., Boccaccini, A.R., Dlouhý, I., Reece, M., Toughened and Machinable Glass Matrix Composites Reinforced with Graphene and Graphene-Oxide Nano Platelets (2013) Sci. Technol. Adv. Mater., 14, p. 055007 Pure ZrB2 powder was Flash sintered in an SPS furnace (FSPS). The samples were densified up to 95.0% in 35 s under an applied pressure of 16 MPa. Compared to Conventional SPS (CSPS), the newly developed FSPS technique resulted in an unprecedented energy and time savings of about 95% and 98% respectively. ZrB2 monoliths obtained by CSPS and FSPS were compared with respect to microstructures, densification behavior, and grain growth. The developed methodology might find application to a wide range of highly conductive ceramics as such refractory borides and carbides. © 2014 The American Ceramic Society.Export Date: 19 August 2014 CODEN: JACTA Correspondence Address: Reece, M.J.; School of Engineering and Material Science, Queen Mary University of London, London E1 4NS, United Kingdom; email: [email protected] Funding Details: EP/K008749/1, EPSRC, European Commission Funding Details: FP7 2007-2013, EC, European Commission References: Cologna, M., Rashkova, B., Raj, R., Flash Sintering of Nanograin Zirconia in <5 s at 850°C (2010) J. Am. Ceram. Soc., 93 (11), pp. 3556-3559; Downs, J.A., Sglavo, V.M., Electric Field Assisted Sintering of Cubic Zirconia at 390°C (2013) J. Am. Ceram. Soc., 96 (5), pp. 1342-1344; Muccillo, R., Muccillo, E.N.S., An Experimental Setup for Shrinkage Evaluation during Electric Field-Assisted Flash Sintering: Application to Yttria-Stabilized Zirconia (2013) J. Eur. Ceram. Soc., 33 (3), pp. 515-520; Muccillo, R., Muccillo, E.N.S., Electric Field-Assisted Flash Sintering of Tin Dioxide (2014) J. Eur. Ceram. Soc., 34 (4), pp. 915-923; Jha, S.K., Raj, R., The Effect of Electric Field on Sintering and Electrical Conductivity of Titania (2014) J. Am. Ceram. Soc., 97 (2), pp. 527-534; Zapata-Solvas, E., Bonilla, S., Wilshaw, P.R., Todd, R.I., Preliminary Investigation of Flash Sintering of SiC (2013) J. Eur. Ceram. Soc., 33 (1314), pp. 2811-2816; Grasso, S., Sakka, Y., Rendtorff, N., Hu, C., Maizza, G., Borodianska, H., Vasylkiv, O., Modeling of the Temperature Distribution of flash sintered Zirconia (2011) Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/J. Ceram. Soc. Jpn., 119 (1386), pp. 144-146; Park, J., Chen, I.W., In Situ Thermometry Measuring Temperature Flashes Exceeding 1,700°C in 8 mol% Y2O3-Stablized Zirconia under Constant-Voltage Heating (2013) J. Am. Ceram. Soc., 96 (3), pp. 697-700; Zapata-Solvas, E., Jayaseelan, D.D., Lin, H.T., Brown, P., Lee, W.E., Mechanical Properties of ZrB2- and HfB2-Based Ultra-High Temperature Ceramics Fabricated by Spark Plasma Sintering (2013) J. Eur. Ceram. Soc., 33 (7), pp. 1373-1386; Grasso, S., Sakka, Y., Maizza, G., Electric Current Activated/Assisted Sintering (ECAS): A Review of Patents 1906-2008 (2009) Sci. Technol. Adv. Mater., 10 (5), p. 053001; Mallik, M., Kailath, A.J., Ray, K.K., Mitra, R., Electrical and Thermophysical Properties of ZrB2 and HfB 2 Based Composites (2012) J. Eur. Ceram. Soc., 32 (10), pp. 2545-2555; Steil, M.C., Marinha, D., Aman, Y., Gomes, J.R.C., Kleitz, M., From Conventional Ac Flash-Sintering of YSZ to Hyper-Flash and Double Flash (2013) J. Eur. Ceram. Soc., 33 (11), pp. 2093-2101; Ortiz, A.L., Zamora, V., Rodríguez-Rojas, F., A Study of the Oxidation of ZrB2 Powders during High-Energy Ball-Milling in Air (2012) Ceram. Int., 38 (4), pp. 2857-2863; Porwal, H., Tatarko, P., Grasso, S., Hu, C., Boccaccini, A.R., Dlouhý, I., Reece, M., Toughened and Machinable Glass Matrix Composites Reinforced with Graphene and Graphene-Oxide Nano Platelets (2013) Sci. Technol. Adv. Mater., 14, p. 055007 Pure ZrB2 powder was Flash sintered in an SPS furnace (FSPS). The samples were densified up to 95.0% in 35 s under an applied pressure of 16 MPa. Compared to Conventional SPS (CSPS), the newly developed FSPS technique resulted in an unprecedented energy and time savings of about 95% and 98% respectively. ZrB2 monoliths obtained by CSPS and FSPS were compared with respect to microstructures, densification behavior, and grain growth. The developed methodology might find application to a wide range of highly conductive ceramics as such refractory borides and carbides. © 2014 The American Ceramic Society.S.G. was supported by EPSRC (EP/K008749/1, XMat). T.S. was supported by EC FP7 2007-2013 (ADMACOM). O.C. was supported by CONACYT (Consejo Nacional de Ciencia y Tecnología, México)

Why business angels reject investment opportunities: Is it personal?

A major focus of research on business angels has examined their decision-making processes and investment criteria. As business angels reject most of the opportunities that they receive, this article explores the reasons informing such decisions. In view of angel heterogeneity, investment opportunities might be expected to be rejected for differing reasons. Two sources of data are used to examine this issue. Face-to-face interviews with 30 business angels in Scotland and Northern Ireland provided information on typical ‘deal killers’. This was complemented by an Internet survey of United Kingdom that attracted responses from 238 UK business angels. The findings confirm that the main reason for rejection relates to the entrepreneur/management team. However, angel characteristics do not explain the number of reasons given for opportunity rejection nor do they predict the reasons for rejecting investment opportunities. This could be related to the increasing trend for business angels to join organised groups which, in turn, leads to the development of a shared repertoire of investment approaches. We suggest the concept of ‘communities-of-practice’ as an explanation for this finding

Channel choice complications:Exploring the multiplex nature of citizens' channel choices

Part 2: E-Government Services and Open GovernmentInternational audienceIn spite of massive investment and increased adoption of digital services, citizens continue to use traditional channels to interact with public organizations. The channel choice (CC) field of research tries to understand citizens’ interactions with public authorities to make the interaction more efficient and increase citizen satisfaction. However, most studies have been conducted either as surveys of hypothetical services or in experimental settings, leading to a lack of empirical data from actual use contexts. Therefore, we present the results of a sequential mixed methods study which combines observations of citizen-caseworker interaction in a call center, contextual interviews with callers, and a survey classifying topics from 10,000 telephone calls. We contribute to the CC field and practice with rich empirical data from studies of actual channel choices. Specifically, the study explores the multiplex nature of real-life CC and demonstrate how telephone calls can be part of a process, which occurs across both traditional and digital channels. Moreover, we identify problems, which cause telephone calls related to digital services, and classify these in two groups: information related problems and action related problems

Optimum spectral window for imaging of art with optical coherence tomography

Optical Coherence Tomography (OCT) has been shown to have potential for important applications in the field of art conservation and archaeology due to its ability to image subsurface microstructures non-invasively. However, its depth of penetration in painted objects is limited due to the strong scattering properties of artists’ paints. VIS-NIR (400 nm – 2400 nm) reflectance spectra of a wide variety of paints made with historic artists’ pigments have been measured. The best spectral window with which to use optical coherence tomography (OCT) for the imaging of subsurface structure of paintings was found to be around 2.2 μm. The same spectral window would also be most suitable for direct infrared imaging of preparatory sketches under the paint layers. The reflectance spectra from a large sample of chemically verified pigments provide information on the spectral transparency of historic artists’ pigments/paints as well as a reference set of spectra for pigment identification. The results of the paper suggest that broadband sources at ~2 microns are highly desirable for OCT applications in art and potentially material science in general

Standing genetic variation and compensatory evolution in transgenic organisms: a growth-enhanced salmon simulation

Genetically modified strains usually are generated within defined genetic backgrounds to minimize variation for the engineered characteristic in order to facilitate basic research investigations or for commercial application. However, interactions between transgenes and genetic background have been documented in both model and commercial agricultural species, indicating that allelic variation at transgene-modifying loci are not uncommon in genomes. Engineered organisms that have the potential to allow entry of transgenes into natural populations may cause changes to ecosystems via the interaction of their specific phenotypes with ecosystem components and services. A transgene introgressing through natural populations is likely to encounter a range of natural genetic variation (among individuals or sub-populations) that could result in changes in phenotype, concomitant with effects on fitness and ecosystem consequences that differ from that seen in the progenitor transgenic strain. In the present study, using a growth hormone transgenic salmon example, we have modeled selection of modifier loci (single and multiple) in the presence of a transgene and have found that accounting for genetic background can significantly affect the persistence of transgenes in populations, potentially reducing or reversing a “Trojan gene” effect. Influences from altered life history characteristics (e.g., developmental timing, age of maturation) and compensatory demographic/ecosystem controls (e.g., density dependence) also were found to have a strong influence on transgene effects. Further, with the presence of a transgene in a population, genetic backgrounds were found to shift in non-transgenic individuals as well, an effect expected to direct phenotypes away from naturally selected optima. The present model has revealed the importance of understanding effects of selection for background genetics on the evolution of phenotypes in populations harbouring transgenes

Web-based alcohol screening and brief intervention for Māori and non-Māori: the New Zealand e-SBINZ trials

BACKGROUND: Hazardous alcohol consumption is a leading modifiable cause of mortality and morbidity among young people. Screening and brief intervention (SBI) is a key strategy to reduce alcohol-related harm in the community, and web-based approaches (e-SBI) have advantages over practitioner-delivered approaches, being cheaper, more acceptable, administrable remotely and infinitely scalable. An efficacy trial in a university population showed a 10-minute intervention could reduce drinking by 11% for 6 months or more among 17-24 year-old undergraduate hazardous drinkers. The e-SBINZ study is designed to examine the effectiveness of e-SBI across a range of universities and among Māori and non-Māori students in New Zealand. METHODS/DESIGN: The e-SBINZ study comprises two parallel, double blind, multi-site, individually randomised controlled trials. This paper outlines the background and design of the trial, which is recruiting 17-24 year-old students from seven of New Zealand's eight universities. Māori and non-Māori students are being sampled separately and are invited by e-mail to complete a web questionnaire including the AUDIT-C. Those who score >4 will be randomly allocated to no further contact until follow-up (control) or to assessment and personalised feedback (intervention) via computer. Follow-up assessment will occur 5 months later in second semester. Recruitment, consent, randomisation, intervention and follow-up are all online. Primary outcomes are (i) total alcohol consumption, (ii) frequency of drinking, (iii) amount consumed per typical drinking occasion, (iv) the proportions exceeding medical guidelines for acute and chronic harm, and (v) scores on an academic problems scale. DISCUSSION: The trial will provide information on the effectiveness of e-SBI in reducing hazardous alcohol consumption across diverse university student populations with separate effect estimates for Māori and non-Māori students. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12610000279022

Role for Circadian Clock Genes in Seasonal Timing: Testing the Bunning Hypothesis

A major question in chronobiology focuses around the “Bünning hypothesis” which implicates the circadian clock in photoperiodic (day-length) measurement and is supported in some systems (e.g. plants) but disputed in others. Here, we used the seasonally-regulated thermotolerance of Drosophila melanogaster to test the role of various clock genes in day-length measurement. In Drosophila, freezing temperatures induce reversible chill coma, a narcosis-like state. We have corroborated previous observations that wild-type flies developing under short photoperiods (winter-like) exhibit significantly shorter chill-coma recovery times (CCRt) than flies that were raised under long (summer-like) photoperiods. Here, we show that arrhythmic mutant strains, per01, tim01 and ClkJrk, as well as variants that speed up or slow down the circadian period, disrupt the photoperiodic component of CCRt. Our results support an underlying circadian function mediating seasonal daylength measurement and indicate that clock genes are tightly involved in photo- and thermo-periodic measurements

Taking the strain? Impact of glaucoma on patients' informal caregivers

Purpose: To estimate informal caregiver (ICG) strain in people from a glaucoma clinic. Methods: Patients with glaucoma were consecutively identified from a single clinic in England for a cross-sectional postal survey. The sample was deliberately enriched with a number of patients designated as having advanced glaucoma (visual field [VF] mean deviation worse than -12 dB in both eyes). Patients were asked to identify an ICG who recorded a Modified Caregiver Strain Index (MCSI), a validated 13 item instrument scored on a scale of 0-26. Previous research has indicated mean MCSI to be >10 in Multiple Sclerosis and Parkinson’s disease. All participants gave a self-reported measure of general health (EQ5D). Results: Responses from 105 patients (43% of those invited) were analysed; only 38 of the 105 named an ICG. Mean (95% confidence interval [CI]) MCSI was 2.4 (1.3, 3.6) and only three ICGs recorded a MCSI > 7. The percentage of patients with an ICG was much higher in patients with advanced VF loss (82%; 9/11) when compared to those with non-advanced VF loss (31%; 29/94; p=0.001). Mean (standard deviation) MCSI was considerably inflated in the advanced patients (5.6 [4.9] vs 1.5 [2.2] for non-advanced; p=0.040). Worsening VF and poorer self-reported general health (EQ5D) of the patient were associated with worsening MCSI. Conclusion: ICG strain, as measured by MCSI, for patients with non-advanced glaucoma is negligible, compared to other chronic disease. ICG strain increases moderately with worsening VFs but this could be partly explained by worse general health in our sample of patients

Does Landscape Fragmentation Influence Sex Ratio of Dioecious Plants? A Case Study of Pistacia chinensis in the Thousand-Island Lake Region of China

The Thousand-Island Lake region in Zhejiang Province, China is a highly fragmented landscape with a clear point-in-time of fragmentation as a result of flooding to form the reservoir. Islands in the artificial lake were surveyed to examine how population sex ratio of a dioecious plant specie Pistacia chinensis B. was affected by landscape fragmentation. A natural population on the mainland near the lake was also surveyed for comparison. Population size, sex ratio and diameter at breast height (DBH) of individuals were measured over 2 years. More than 1,500 individuals, distributed in 31 populations, were studied. Soil nitrogen in the different populations was measured to identify the relationship between sex ratio and micro-environmental conditions. In accordance with the results of many other reports on biased sex ratio in relation to environmental gradient, we found that poor soil nitrogen areas fostered male-biased populations. In addition, the degree of sex ratio bias increased with decreasing population size and population connectivity. The biased sex ratios were only found in younger individuals (less than 50 years old) in small populations, while a stable 1∶1 sex ratio was found in the large population on the mainland. We concluded that the effects of landscape fragmentation on the dioecious population sex ratio were mainly achieved in relation to changing soil nitrogen conditions in patches and pollen limitation within and among populations. Large populations could maintain a more suitable environment in terms of nutrient conditions and pollen flow, subsequently maintaining a stable sex ratio in dioecious plant populations. Both micro-environmental factors and spatial structure should be considered in fragmented landscape for the conservation of dioecious plant species

Use of antidepressant medications in relation to the incidence of breast cancer

Although associations have been reported between antidepressant use and risk of breast cancer, the findings have been inconsistent. We conducted a population-based case–control study among women enrolled in Group Health Cooperative (GHC), a health maintenance organization in Washington State. Women with a first primary breast cancer diagnosed between 1990 and 2001 were identified (N=2904) and five controls were selected for each case (N=14396). Information on antidepressant use was ascertained through the GHC pharmacy database and on breast cancer risk factors and screening mammograms from GHC records. Prior to one year before diagnosis of breast cancer, about 20% of cases and controls had used tricyclic antidepressants (adjusted odds ratio=1.06, 95% CI 0.94–1.19) and 6% of each group had used selective serotonin reuptake inhibitors (OR=0.98, 95% CI 0.80–1.18). There also were no differences between cases and controls with regard to the number of prescriptions filled or the timing of use. Taken as a whole, the results from this and other studies to date do not indicate an altered risk of breast cancer associated with the use of antidepressants overall, by class, or for individual antidepressants