The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Emmanouil Kioupakis - One of the best experts on this subject based on the ideXlab platform.
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lattice constant and band gap tuning in wurtzite and zincblende bingan alloys
Journal of Applied Physics, 2019Co-Authors: Kevin Greenman, Logan Williams, Emmanouil KioupakisAbstract:InGaN light-emitting diodes (LEDs) are more efficient and cost effective than incandescent and Fluorescent Lighting, but lattice mismatch limits the thickness of InGaN layers that can be grown on GaN without performance-degrading dislocations. In this work, we apply hybrid density functional theory calculations to investigate the thermodynamic stability, lattice parameters, and bandgaps of wurtzite and zincblende quaternary BInGaN alloys. We find that the wurtzite phase is more stable and can be lattice matched to GaN for BInGaN compositions containing up to ∼30% boron. The lattice match with GaN decreases strain and enables thicker active layers that mitigate Auger recombination and increase the efficiency of the LEDs. The bandgap of the alloy remains tunable throughout the visible spectrum. Our results indicate that BInGaN alloys are promising alternatives to InGaN for high-efficiency, high-power LEDs.InGaN light-emitting diodes (LEDs) are more efficient and cost effective than incandescent and Fluorescent Lighting, but lattice mismatch limits the thickness of InGaN layers that can be grown on GaN without performance-degrading dislocations. In this work, we apply hybrid density functional theory calculations to investigate the thermodynamic stability, lattice parameters, and bandgaps of wurtzite and zincblende quaternary BInGaN alloys. We find that the wurtzite phase is more stable and can be lattice matched to GaN for BInGaN compositions containing up to ∼30% boron. The lattice match with GaN decreases strain and enables thicker active layers that mitigate Auger recombination and increase the efficiency of the LEDs. The bandgap of the alloy remains tunable throughout the visible spectrum. Our results indicate that BInGaN alloys are promising alternatives to InGaN for high-efficiency, high-power LEDs.
Jennifer A Veitch - One of the best experts on this subject based on the ideXlab platform.
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full spectrum Fluorescent Lighting a review of its effects on physiology and health
Psychological Medicine, 2001Co-Authors: Shelley L. Mccoll, Jennifer A VeitchAbstract:Background. Full-spectrum Fluorescent Lighting (FSFL) has been credited with causing dramatic beneficial effects on a wide variety of behaviours, mental health outcomes and physical health effects, as compared to other Fluorescent lamp types. These effects are hypothesized to occur because of similarity between FSFL emissions and daylight, which is said to have evolutionary superiority over other light sources. Method. This review, covering the period 1941–1999, critically considers the evidence for direct effects of FSFL through skin absorption as well as indirect effects on hormonal and neural processes. Conclusions. Overall, the evidence does not show dramatic effects of Fluorescent lamp type on behaviour or health, neither does it support the evolutionary hypothesis.
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A critical examination of perceptual and cognitive effects attributed to full-spectrum Fluorescent Lighting
Ergonomics, 2001Co-Authors: Jennifer A Veitch, Shelley L. MccollAbstract:Full-spectrum Fluorescent Lighting (FSFL) has been credited with causing dramatic improvements in vision, perception and cognitive performance as compared with other Fluorescent lamp types. These effects are hypothesized to occur because of similarity between FSFL emissions and daylight, which is said to have evolutionary superiority over other light sources. This review, covering 1945-98, critically considers the evidence for these claims. In general, poor-quality research has resulted in an absence of simple deterministic effects that can be confidently attributed to Fluorescent lamp type. Promising avenues for Lighting behaviour research include investigations of cognitive mediators of Lighting-behaviour relationships, and flicker rates and colour rendering effects on visual processing, appearance judgements and affect. Good Lighting solutions are more complex than lamp type specification.
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full spectrum Fluorescent Lighting effects on people a critical review
1998Co-Authors: Jennifer A Veitch, Shelley L. MccollAbstract:Full-spectrum Fluorescent Lighting has been credited with causing dramatic improvements in a wide variety of behaviours, mental health outcomes, and physical health effects. These effects include reduction in dental caries, improved classroom behaviour in schoolchildren, enhanced academic achievement, more efficient visual performance, more attractive appearance of both people and spaces, and improved mood in cases of seasonal depression. Popular media reports have tended to emphasize studies that have demonstrated differences in outcomes as a function of light source spectral power distribution. However, the scientific literature also includes reports with null and contradictory effects. This comprehensive review covers the period 1945-1993 and includes a critical appraisal of the methodology in each study. The studies are grouped according to their dependent variables under the broad headings "Behaviour and Performance", "Mental Well-Being and Affect", and "Physiology and Health". In general, the quality of the research is poor, making it difficult to determine whether or not treatment effects may legitimately be attributed to light source spectral power distribution. A few rigorous investigations of full-spectrum Fluorescent Lighting have demonstrated small effects; however, few researchers have taken up the challenge to replicate their work. These small effects do not support the claims that full-spectrum Fluorescent Lighting will produce better performance, mood, or health in the general population. More fruitful avenues for future research include investigations of other Lighting parameters including intensity, variability, and flicker and an emphasis on the possibility that individual differences exist in sensitivity to the spectral composition of light sources. The role of mental processes -for example, beliefs, memories, and expectations -in mediating the effects of Lighting on behaviour stands out as most promising for future research.
Shelley L. Mccoll - One of the best experts on this subject based on the ideXlab platform.
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full spectrum Fluorescent Lighting a review of its effects on physiology and health
Psychological Medicine, 2001Co-Authors: Shelley L. Mccoll, Jennifer A VeitchAbstract:Background. Full-spectrum Fluorescent Lighting (FSFL) has been credited with causing dramatic beneficial effects on a wide variety of behaviours, mental health outcomes and physical health effects, as compared to other Fluorescent lamp types. These effects are hypothesized to occur because of similarity between FSFL emissions and daylight, which is said to have evolutionary superiority over other light sources. Method. This review, covering the period 1941–1999, critically considers the evidence for direct effects of FSFL through skin absorption as well as indirect effects on hormonal and neural processes. Conclusions. Overall, the evidence does not show dramatic effects of Fluorescent lamp type on behaviour or health, neither does it support the evolutionary hypothesis.
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A critical examination of perceptual and cognitive effects attributed to full-spectrum Fluorescent Lighting
Ergonomics, 2001Co-Authors: Jennifer A Veitch, Shelley L. MccollAbstract:Full-spectrum Fluorescent Lighting (FSFL) has been credited with causing dramatic improvements in vision, perception and cognitive performance as compared with other Fluorescent lamp types. These effects are hypothesized to occur because of similarity between FSFL emissions and daylight, which is said to have evolutionary superiority over other light sources. This review, covering 1945-98, critically considers the evidence for these claims. In general, poor-quality research has resulted in an absence of simple deterministic effects that can be confidently attributed to Fluorescent lamp type. Promising avenues for Lighting behaviour research include investigations of cognitive mediators of Lighting-behaviour relationships, and flicker rates and colour rendering effects on visual processing, appearance judgements and affect. Good Lighting solutions are more complex than lamp type specification.
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full spectrum Fluorescent Lighting effects on people a critical review
1998Co-Authors: Jennifer A Veitch, Shelley L. MccollAbstract:Full-spectrum Fluorescent Lighting has been credited with causing dramatic improvements in a wide variety of behaviours, mental health outcomes, and physical health effects. These effects include reduction in dental caries, improved classroom behaviour in schoolchildren, enhanced academic achievement, more efficient visual performance, more attractive appearance of both people and spaces, and improved mood in cases of seasonal depression. Popular media reports have tended to emphasize studies that have demonstrated differences in outcomes as a function of light source spectral power distribution. However, the scientific literature also includes reports with null and contradictory effects. This comprehensive review covers the period 1945-1993 and includes a critical appraisal of the methodology in each study. The studies are grouped according to their dependent variables under the broad headings "Behaviour and Performance", "Mental Well-Being and Affect", and "Physiology and Health". In general, the quality of the research is poor, making it difficult to determine whether or not treatment effects may legitimately be attributed to light source spectral power distribution. A few rigorous investigations of full-spectrum Fluorescent Lighting have demonstrated small effects; however, few researchers have taken up the challenge to replicate their work. These small effects do not support the claims that full-spectrum Fluorescent Lighting will produce better performance, mood, or health in the general population. More fruitful avenues for future research include investigations of other Lighting parameters including intensity, variability, and flicker and an emphasis on the possibility that individual differences exist in sensitivity to the spectral composition of light sources. The role of mental processes -for example, beliefs, memories, and expectations -in mediating the effects of Lighting on behaviour stands out as most promising for future research.
Joe D Buckley - One of the best experts on this subject based on the ideXlab platform.
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addition of tea catechins and vitamin c on sensory evaluation colour and lipid stability during chilled storage in cooked or raw beef and chicken patties
Meat Science, 2005Co-Authors: Mitsuru Mitsumoto, M N Ogrady, Joseph P Kerry, Joe D BuckleyAbstract:Abstract The effects of addition of tea catechins (TC) and vitamin C (VC) on sensory evaluation, colour and lipid stability in cooked or raw beef and chicken meat patties during refrigerated storage were studied. Fresh beef striploin and chicken breast muscles were minced, following removal of external fat and connective tissue. Following mincing, beef and chicken were assigned to one of the following five treatments: control (meat treated with no antioxidant); TC200, meat plus 200 mg TC/kg muscle; TC400, meat plus 400 mg TC/kg muscle; VC200, meat plus 200 mg VC/kg muscle, VC400, meat plus 400 mg VC/kg muscle. Sodium chloride (1%) was added to all samples. Patties (125 g portions), formed from the above-treated minced meat, were oven cooked, cooled, and packaged in 30% CO2:70% N2. Fresh raw beef and chicken patties were packaged in 80% O2:20% CO2. All samples were stored for up to 7 days under Fluorescent Lighting at 4 °C. Sensory parameters (colour, flavour, taste, tenderness and overall acceptability) were evaluated on cooked beef and chicken patties after 1, 3 and 6 days of storage. Surface colour (Hunter L, a and b values), and lipid oxidation (2-thiobarbituric acid reactive substances) were measured on days 1, 3 and 6 of storage for cooked meats and on days 2 and 7 for raw beef and chicken. Tea catechins addition (200 or 400 mg/kg) to minced meat caused (P
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addition of tea catechins and vitamin c on sensory evaluation colour and lipid stability during chilled storage in cooked or raw beef and chicken patties
Meat Science, 2005Co-Authors: Mitsuru Mitsumoto, M N Ogrady, Joseph P Kerry, Joe D BuckleyAbstract:The effects of addition of tea catechins (TC) and vitamin C (VC) on sensory evaluation, colour and lipid stability in cooked or raw beef and chicken meat patties during refrigerated storage were studied. Fresh beef striploin and chicken breast muscles were minced, following removal of external fat and connective tissue. Following mincing, beef and chicken were assigned to one of the following five treatments: control (meat treated with no antioxidant); TC200, meat plus 200 mg TC/kg muscle; TC400, meat plus 400 mg TC/kg muscle; VC200, meat plus 200 mg VC/kg muscle, VC400, meat plus 400 mg VC/kg muscle. Sodium chloride (1%) was added to all samples. Patties (125 g portions), formed from the above-treated minced meat, were oven cooked, cooled, and packaged in 30% CO(2):70% N(2). Fresh raw beef and chicken patties were packaged in 80% O(2):20% CO(2). All samples were stored for up to 7 days under Fluorescent Lighting at 4 °C. Sensory parameters (colour, flavour, taste, tenderness and overall acceptability) were evaluated on cooked beef and chicken patties after 1, 3 and 6 days of storage. Surface colour (Hunter L, a and b values), and lipid oxidation (2-thiobarbituric acid reactive substances) were measured on days 1, 3 and 6 of storage for cooked meats and on days 2 and 7 for raw beef and chicken. Tea catechins addition (200 or 400 mg/kg) to minced meat caused (P<0.05) discolouration in cooked beef and chicken meat patties and significantly reduced (P<0.001) lipid oxidation in cooked or raw beef patties compared to the control. Beef, either raw or cooked, was more susceptible (P<0.01) to oxidation compared to chicken. Raw meat stored in high oxygen conditions was more susceptible to lipid oxidation than cooked meat stored in anaerobic conditions. Tea catechins treatments (TC200 and TC400) inhibited (P<0.05) lipid oxidation in raw beef to a greater extent than vitamin C treatments (VC200 and VC400). These results indicate that tea catechins are potent natural antioxidants and exhibit greater antioxidant efficacy compared to vitamin C.
Yumeng You - One of the best experts on this subject based on the ideXlab platform.
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high responsivity phototransistors based on few layer res2 for weak signal detection
Advanced Functional Materials, 2016Co-Authors: Erfu Liu, Mingsheng Long, Junwen Zeng, Wei Luo, Yaojia Wang, Yiming Pan, Wei Zhou, Baigeng Wang, Yumeng YouAbstract:2D transition metal dichalcogenides are emerging with tremendous potential in many optoelectronic applications due to their strong light–matter interactions. To fully explore their potential in photoconductive detectors, high responsivity is required. Here, high responsivity phototransistors based on few-layer rhenium disulfide (ReS2) are presented. Depending on the back gate voltage, source drain bias and incident optical light intensity, the maximum attainable photoresponsivity can reach as high as 88 600 A W−1, which is a record value compared to other individual 2D materials with similar device structures and two orders of magnitude higher than that of monolayer MoS2. Such high photoresponsivity is attributed to the increased light absorption as well as the gain enhancement due to the existence of trap states in the few-layer ReS2 flakes. It further enables the detection of weak signals, as successfully demonstrated with weak light sources including a lighter and limited Fluorescent Lighting. Our studies underscore ReS2 as a promising material for future sensitive optoelectronic applications.
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high responsivity phototransistors based on few layer res2 for weak signal detection
arXiv: Materials Science, 2015Co-Authors: Erfu Liu, Mingsheng Long, Junwen Zeng, Wei Luo, Yaojia Wang, Yiming Pan, Wei Zhou, Baigeng Wang, Yumeng YouAbstract:Two-dimensional transition metal dichalcogenides are emerging with tremendous potential in many optoelectronic applications due to their strong light-matter interactions. To fully explore their potential in photoconductive detectors, high responsivity and weak signal detection are required. Here, we present high responsivity phototransistors based on few-layer rhenium disulfide (ReS2). Depending on the back gate voltage, source drain bias and incident optical light intensity, the maximum attainable photoresponsivity can reach as high as 88,600 A W-1, which is a record value compared to other two-dimensional materials with similar device structures and two orders of magnitude higher than that of monolayer MoS2. Such high photoresponsivity is attributed to the increased light absorption as well as the gain enhancement due to the existence of trap states in the few-layer ReS2 flakes. It further enables the detection of weak signals, as successfully demonstrated with weak light sources including a lighter and limited Fluorescent Lighting. Our studies underscore ReS2 as a promising material for future sensitive optoelectronic applications.