Thixoforming of A356/SiC and A356/TiB2 Nanocomposites Fabricated by a Combination of Green Compact Nanoparticle Incorporation and Ultrasonic Treatment of the Melted Compact

Thixoforming is a type of semi-solid processing which is based on forming metals in the semi-solid state rather than fully liquid or solid state. There have been no reports of the thixoforming of nanocomposites in the literature. The incorporation of ceramic nanoparticles into liquid metals is a challenging task for the fabrication of metal matrix nanocomposites due to their large surface-to-volume ratio and poor wettability. Previous research work by a number of workers has highlighted the challenges with the incorporation of nanoparticles into liquid aluminum alloy. In the present study, SiC and TiB₂ nanoparticles with an average diameter between 20 and 30 nm were firstly incorporated into green compacts by a powder forming route, and then the compacts were melted and treated ultrasonically. The microstructural studies reveal that the engulfment and relatively effective distribution of the nanoparticles into the melt were achieved. The hardness was considerably improved with only 0.8 wt pct addition of the nanoparticles. The nanocomposites were successfully thixoformed at a solid fraction between 0.65 and 0.70. The microstructures, hardness, and tensile mechanical properties of the thixoformed nanocomposites were investigated and compared with those of the as-received A356 and thixoformed A356 alloys. The tensile properties of the thixoformed nanocomposites were significantly enhanced compared to thixoformed A356 alloy without reinforcement, indicating the strengthening effects of the nanoparticles.     

Esterification of Fatty Acids in Greases to Fatty Acid Methyl Esters with Highly Active Diphenylamine Salts

Diphenylamine sulfate (DPAS) and diphenylamine hydrochloride (DPACl) salts were found to be highly active catalysts for esterification and substantial transesterification of inexpensive greases to fatty acid methyl esters (FAME). In the presence of catalytic amounts of DPAS or DPACl and excess methanol, the free fatty acids as well as the acylglycerols in waste greases were converted to FAME at 125 °C within 1 h. Although the DPAS and DPACl catalysts were found to have similar catalytic activities to their parent liquid acids (i.e., sulfuric and hydrochloric acids) the diphenylammonium salts are much easier to work with than concentrated liquid acids.     

Impact of individual atmospheric parameters on CPV system power,energy yield and cost of energy

The performance of concentrator photovoltaic systems can be characterised by the power output under reference conditions and the output energy yield under realistic solar illumination. For a range of locations, the frequency distribution of individual atmospheric parameters and their quantitative impact on power output of a concentrator photovoltaic system have been evaluated, with aerosols shown to have a substantial impact on performance at many sites. Limited knowledge of atmospheric parameters results in a difference of up to 75% in simulated energy yield over an annual period and up to 75% deviation in the expected levelised cost of energy. Copyright © 2013 John Wiley & Sons, Ltd.     

The use of continuous-flow electrophoresis to remove pectin in the purification of the minor pectinesterases in lemon fruits (citrus limon)

Continuous-flow electrophoresis was used to separate pectin and coloured substances from extracts of lemon pectinesterase. Two minor lemon pectinesterases were subsequently separated from two major pectinesterases, using chromatography on Sephadex G-75 and CM-Sephadex C-50. One minor pectinesterase was stable at low pH, showed the same initial pectinesterase activity at 88°C as at 25°C, and was active at 85°C for 9 min. This enzyme destabilised the cloud of single-strength lemon juice. It is suggested that the minor pectinesterases might not be true isozymes, but could arise from association of a major enzyme with pectin.     

Stigmatised choices: social class, social exclusion and secondary school markets in the inner city

The transition to secondary school is rarely conceptualised as an important influence in maintaining and contributing to wider processes of social exclusion in the inner city. This article argues that the seeds of social exclusion are sown in under-resourced, struggling inner-city schooling, and their germination is found in class practices, particularly the exclusionary secondary school choice practices of the middle classes. Drawing on Jordan's conceptualisation of the choices available to parents in the new UK educational markets, we examine middle-class strategies of 'voting with the feet', exit and self-exclusion, plus the more covert practice of 'exchanging addresses'. The article examines how these processes have implications for the construction of a polarized market where some schools are 'demonized' and others 'idealized' along class, racial and ethnic lines. It also raises questions about what it might mean for the mainly working-class children who have no choice but to go to such demonized schools.     

Discontinuation of long term orthokeratology lens wear and subsequent refractive surgery outcome

Purpose

To report a case of lens discontinuation in a long term orthokeratology (OK) lens wearer and describe regression in refraction, corneal topography, and corneal thickness over 408 days after lens discontinuation. Furthermore, the outcome of subsequent LASIK treatment is also reported.

Estrogenic induction of spermatogenesis in the hypogonadal (hpg) mouse: role of androgens

Testicular development is arrested in the hypogonadal (hpg) mouse due to a congenital deficiency of hypothalamic gonadotropin-releasing hormone synthesis. Previous studies have demonstrated that chronic treatment of these mice with estradiol induces testicular maturation and qualitatively normal spermatogenesis, but it is not known whether these are direct effects via estrogen receptors expressed in the testis, or indirect actions via the pituitary gland. The aim of the current studies was to determine whether the actions of estradiol require the presence of androgens. Sensitive assays revealed that chronic estradiol treatment produced time-dependent increases in pituitary FSH production but no increases in pituitary LH or testicular testosterone content could be detected. As a functional test of androgen dependence, hpg mice were treated for 70 days with estradiol plus Casodex (bicalutamide), an androgen receptor antagonist. Casodex treatment markedly attenuated both the estradiol-induced increase in testicular weight and the proliferation of the seminiferous epithelium, as revealed by morphometric analysis. However, it did not affect the estradiol-induced increase in pituitary FSH content, nor did it affect estradiol-induced increases in the weight of the seminal vesicles and epididymides. We conclude that increased FSH production is not sufficient to explain the increase in testicular development induced by estradiol in hpg mice; there is a requirement for functional androgen receptors for induction of testicular growth.     

Sex, BMI and age in addition to dietary intakes influence blood concentrations and congener profiles of dioxins and PCBs

Scope: The aim of this study was to i) characterize dietary polychlorinated biphenyls (PCBs) and dioxin exposure in consumers of fish from the PCB contaminated Lake Mjøsa in Norway ii) examine the influence of demographic factors on blood concentrations and congener composition of dioxins and PCBs, iii) characterize dietary sources and possible exposures above tolerable intake. Methods and results: Blood samples were analysed for dioxin‐like (dl) compounds (PCDD/Fs and dl‐PCBs) and non‐dl‐PCBs (ndl‐PCBs). Dietary exposures were calculated using food frequency questionnaires (n=64). Men had higher median intake of dl‐compounds than women (1.2 and 0.85 pg TEQ/kg bw/day), but similar blood concentrations (23.3 and 25.8, pg TEQ/g lipid weight (lw)). For non‐dl‐PCBs, intakes (6.5 and 4.5 ng/kg bw/day) and blood concentrations (381 and 224 ng/g lw) were higher in men than in women. Blood concentrations correlated with dietary intakes in men only. Increasing BMI and age elevated blood concentrations mainly in women. Men and women had different blood congener profiles, with a higher share of PCB‐126 in women, despite similar dietary congener profiles. Eleven participants exceeded the tolerable intake for dl‐compounds. Fish from Lake Mjøsa was the main dietary source. Conclusion: The higher influence of BMI and age for women than for men may have implications for risk assessment.     

‘Remember Who You Are Designing For’: An Interview with Baroness Sally Greengross OBE

Baroness Sally Greengross has a long and deep knowledge of issues surrounding ageing. Until 2000 she was Director General of Age Concern for 13 years, and also joint Chair of the Institute of Gerontology at King's College London and Secretary General of Eurolink Age. She is now President/Chief Executive of the International Longevity Centre-UK (ILC-UK), an influential think-tank impacting policy on longevity, ageing and population change. Since 2000, she has been a crossbench (independent) member of the House of Lords and she chairs five All-Party Parliamentary Groups: Dementia, Corporate Responsibility, Intergenerational Futures, Continence Care, and Ageing and Older People (Co-Chair). Here, the Editor of AD, Helen Castle , interviews her on shifting attitudes to ageing and the importance of designing for the older population.