The electrical and optical properties of cadmium selenide

Measurements of thermally stimulated currents, photo conductivity and photoluminescence have been used to study the imperfection centres in photosensitive CdSe crystals. These crystals were grown from the elements using a flow technique. Seven closely spaced, discrete sets of traps, with concentrations between 10(^12) and 10(^14) cm(^-3), lie between 0.15 and 0.36 ev below the conduction band. They empty in the temperature range 90 to 210 K. Two other groups of traps are found after illumination at various temperatures with intense white light.(1) Illumination between 250 and 275 K creates four new sets of traps with associated T.S.C. peaks at 215, 230, 250 and 270 K. Also in this temperature range holes are thermally freed from sensitising centres which lie 0.6 ev above the valence band. The consequent increased recombination substantially modifies the T.S.C. peak shapes and no sensible values of the trapping parameters can be obtained from T.S.C. curve analysis. Illumination at higher temperatures destroys these four centres.(2) Three, further T.S.C. peaks appear at 295, 335 and 365 K as a result of illumination above 250 K. They increase in height with increasing temperature of illumination. Such behaviour can be attributed to either the photochemical creation of traps or the existence of traps surrounded by repulsive potential barriers. The traps have depths of 0.43, 0.52 and 0.63 ev. They have capture cross sections of about l0(^-20) cm(_2) and densities of up to 10(^19) cm(_2).Illumination at increasing temperatures in the range 90 to 400 K results in a progressive reduction in the free electron lifetime. This is due to the photochemical creation of class 1 fast recombination centres. Simultaneously the intensity of a 1.15 p luminescence emission band increases and that of a 0,95 p band decreases. There is no direct evidence to suggest that these effects are related

Photoconductivity of CdS-CdSe granular films: influence of microstructure

We study experimentally the photoconductivity of CdS-CdSe sintered granular films obtained by the screen printing method. We mostly focus on the dependences of photoconductivity on film's microstructure, which varies with changing heat-treatment conditions. The maximum photoconductivity is found for samples with compact packing of individual grains, which nevertheless are separated by gaps. Such a microstructure is typical for films heat-treated during an intermediate (optimal) time. In order to understand whether the dominant mechanism of charge transfer is identical with the one in monocrystals, we perform temperature measurements of photoresistance. Corresponding curves have the same peculiar nonmonotonic shape as in CdSe monocrystals, from which we conclude that the basic mechanism is also the same. It is suggested that the optimal heat-treatment time appears as a result of a competition between two mechanisms: improvement of film's connectivity and its oxidation. Photoresistance is also measured in vacuum and in helium atmosphere, which suppress oxygen and water absorption/chemisorption at intergrain boundaries. We demonstrate that this suppression increases photoconductivity, especially at high temperatures.Comment: 12 pages, 8 figures, final versio

Making makes me feel better: Designing for wellbeing and social values

This paper presents a design-led inquiry, which aimed to explore the benefits on wellbeing for people living with early stage dementia through participatory handcraft workshops. The project took place in a historically immersive environment at an open air living history museum involving a dementia friendly design team consisting of researchers, museum staff, volunteers and people living with dementia. Drawing on historic themes from the museum collections a range of new co-produced items were sold in the museum gift shop. The workshop activities enabled an understanding to be established of living with dementia, the value of making and the abilities of people with dementia. Through the experiences of this small group we unpick the rich detail of the participatory activities in terms of wellbeing. Valuing the contribution of each individual and working side by side we really got to know personalities by observing the nuances of body language, recognising abilities and shifts in confidence. We draw out the value of being ‘in the moment’ and also ‘significant moments of realisation’. Often the participants commented that concentrating on a creative activity in the moment could be absorbing, the close connection with materials was shown to be comforting. We observed a commitment and ownership of the project and increased levels of confidence in participants where they valued learning new skills and felt privileged to work and have access to the historic collections within the museum. The co-design project received positive feedback from the local community and visitor interest through sales. Through the project we sought to support the voice of people with dementia as one participant put it: ‘The trouble is you see, when you’re working everything is fast, you don’t have time to try new things and we’re not in a hurry, making makes me feel better.’ Participan

The perception of sweet, bitter and fatty acid taste and sensitivity to fat by mouthfeel and olfaction : associations with dietary intake, eating behaviour and obesity in premenopausal women : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Albany, New Zealand

Figures are re-used with permission. The PROMISE paper (pp. 325-340) published in JMIR Research Protocols (http://www.researchprotocols.org/2019/8/e14529) is an open access article distributed under a Creative Commons Attribution License 4.0.Background: Individual variability in taste perception may influence diet, possibly modifying eating behaviour and long-term food choice. Research into taste perception and weight status, dietary intake, eating behaviour and endocrine regulators of metabolic health could provide new important insights. Taste perception may be modifiable, and as such may be a target for future intervention strategies which may have the potential to prevent or treat obesity. Objectives: The aims of this study were to determine associations between (1) fatty acid taste, olfaction, mouthfeel of fat, dietary intake, eating behaviour and body mass index (BMI), and (2) associations between taste perception of glucose (sweet taste), quinine (bitter taste) and milk (fat perception) with body composition and hormonal adiposity signals (fasting insulin and leptin), dietary intake and eating behaviour. Design: For the first cross-sectional study, 50 premenopausal women assessed oleic acid taste and olfaction thresholds. BMI was calculated from weight (kg) and height (m). Dietary intake and eating behaviour were evaluated using a food frequency and three-factor eating questionnaire (TFEQ), respectively. Binomial regression analysis was used to model fatty acid taste and olfaction data and fatty acid taster status was determined (hypersensitive, n= 22; hyposensitive, n= 28). For the second cross-sectional study (the PROMISE study), 351 premenopausal Pacific and New Zealand (NZ) European women were recruited and stratified by non-obese and obese groups. Suprathreshold intensity, hedonic liking, and discrimination of taste by a ranking task were measured using a range of concentrations of sweet, bitter, and fat solutions. Participants were classified as likers or dislikers for each tastant using a hierarchical cluster analysis. Body fat (BF) was quantified by dual x-ray absorptiometry. Total energy and macronutrient intake were assessed using a 5-day estimated food record and eating behaviour was assessed by TFEQ. Socioeconomic status was measured by deprivation index (NZDep2013). Logistic and linear regression analyses were used to analyse study outcomes and to adjust for potential confounders (socioeconomic position, age, etc). Both studies were undertaken in Auckland, NZ. Outcomes: The results of the first study showed taste and olfactory detection for oleic acid were positively correlated (r= 0.325; P35 BF% (adjusted, OR 2.9, P35 BF% compared to sweet dislikers (adjusted, OR 2.1, P35 BF% in comparison to bitter dislikers (adjusted, OR 0.4, P< 0.01). Having higher fasting plasma leptin concentration significantly increased the likelihood of being a sweet liker in Pacific and in NZ European combined (adjusted; OR 1.7, P< 0.05), but in NZ European women, the likelihood of this was further increased (adjusted; OR 3.6, P< 0.001). Higher fasting plasma insulin concentration also increased the likelihood of being a sweet liker (adjusted, OR 1.7, P< 0.05). New Zealand European sweet likers had a significantly higher intake of carbohydrates, all sugars and starch (199.4 ± 51.1, 87.9 ± 27.4 and 111.1 ± 34.6 g/day) when compared to sweet taste dislikers (165.9 ± 48.7, 71.4 ± 25.2 and 94.1 ± 34.7 g/day, P< 0.001, P< 0.01, and P< 0.01, respectively), however, this comparison was not significant in Pacific women. NZ European women in the sweet likers group had an increased disinhibited eating behaviour score (P< 0.01). Conclusions: Fatty acid taste perception was found to be associated with olfaction, eating behaviour and body composition. The findings from the PROMISE study have shown differences in sweet taste perception in relation to adiposity which is further associated with circulating plasma leptin and insulin concentrations. Sweet taste perception was associated with dietary intake and eating behaviour in NZ European women. The taste-diet associations observed in NZ European women were not observed in Pacific women. Therefore, population groups with lower metabolic disease risk may have dissimilar taste-diet associations compared to those with a higher metabolic disease risk. Taste perception is a promising target for future weight-loss and intervention strategies due to demonstrating links with dietary intake, eating behaviour and body composition

Investigating acute satiation and meal termination effects of a commercial lipid emulsion : A breakfast meal study

Background: Early clinical studies showed the commercial lipid emulsion Fabuless™ to decrease energy intake (EI) and prevent weight regain, but later studies have failed to confirm this finding. Where appetite suppression has been observed it is commonly attributed to the ileal brake, where emulsified fats pass undigested to the distal small intestine and promote later satiety, but satiety profiles suggest possible transient effects within 15 min. The aim of this study was to determine whether this emulsion promotes short-term satiation and meal termination. Methods: In a randomised cross-over intervention 18 lean men were given 4 lipid preloads immediately prior to a breakfast meal, during which ad libitum food consumption, time to meal termination and VAS-rated appetite scores were measured. Preloads were given as lipid emulsion and lipid control, both alone as a ‘shot’ and combined with a dairy yoghurt: (i) lipid emulsion alone (LE, Fabuless™ 4.2g lipid, 0.2 MJ), (ii) lipid control alone (LC, 4 .2g lipid, 0.2 MJ), (iii) LE + yoghurt (1.2 MJ), (iv) LC + yoghurt (1.2 MJ). Results: Whilst both yoghurt preloads suppressed EI at breakfast relative to the ‘shots’, as expected, neither lipid emulsion suppressed EI or triggered more rapid meal termination when compared to energy matched lipid controls (P > 0.05). There was also no difference in VAS-assessed appetite scores between emulsion and control, for either preload. Conclusions: When consumed with a meal there was no evidence in lean men that this commercial lipid emulsion promotes satiation or suppresses short-term food intake

Sweet Taste Perception in Pacific and NZ European Women is Associated with Dietary Intake and Eating Behaviour

Background: Taste perception may influence long-term dietary preferences, potentiallycontributing to the development of obesity [...