Gas-to-gas heat exchanger design for high performance thermal energy storage

The mathematical modelling and optimization of a gas-to-gas heat exchanger with a non-constant cross sectional area is presented. The design of the cross sectional area of the heat exchanger analyzed is based on an hexagonal mesh, which would be highly impractical to fabricate in a conventional way but could be built relatively easily through modern manufacturing techniques. The geometric configuration proposed allows attaining a high exergy efficiency and a significant cost reduction, measured in terms of volume per unit of exergy transfer. The relationship that exists between the overall exergy efficiency of the heat exchanger and its cost is thoroughly explained throughout the study. The results obtained from the modelling demonstrate the premise that it is possible to realize designs for heat exchangers that are highly exergy-efficient and very cheap, owing to the small volume of material required, if the constrains imposed by the limitations of traditional manufacturing methods are set aside. Furthermore, the study reveals a very important fact: the volume of material in a heat exchanger increases in quadratic proportion to its characteristic dimension, which implies that scaling up the geometry has a strong impact on its cost-effectiveness

Design and characterization of hybrid III–V concentrator photovoltaic–thermoelectric receivers under primary and secondary optical elements

Lattice-matched monolithic triple-junction Concentrator Photovoltaic (CPV) cells (InGa(0.495)P/GaIn(0.012)As/Ge) were electrically and thermally interfaced to two Thermoelectric (TE) Peltier module designs. An electrical and thermal model of the hybrid receivers was modelled in COMSOL Multiphysics software v5.3 to improve CPV cell cooling whilst increasing photon energy conversion efficiency. The receivers were measured for current-voltage characteristics with the CPV cell only (with sylguard encapsulant), under single secondary optical element (SOE) at x2.5 optical concentration, and under Fresnel lens primary optical element (POE) concentration between x313 and x480. Measurements were taken in solar simulators at Cardiff and Jaén Universities, and on-sun with dual-axis tracking at Jaén University. The hybrid receivers were electrically, thermally and theoretically investigated. The electrical performance data for the cells under variable irradiance and cell temperature conditions were measured using the integrated thermoelectric module as both a temperature sensor and as a solid-state heat pump. The performance of six SOE-CPV-TE hybrid devices were evaluated within two 3-receiver strings under primary optical concentration with measured acceptance angles of 1.00o and 0.89o, similar to commercially sourced CPV modules. A six-parameter one-diode equivalent electrical model was developed for the multi-junction CPV cells with SOE and POE. This was applied to extract six model parameters with the experimental I-V curves of type A receiver at 1, 3 and 500 concentration ratios. Standard test conditions (1000W/m2, 25oC and AM1.5G spectrum) were assumed based on trust-region-reflective least squares algorithm in MATLAB. The model fitted the experimental I-V curves satisfactorily with a mean error of 4.44%, and the optical intensity gain coefficient of SOE and POE is as high as 0.91, in comparison with 0.50-0.86 for crossed compound parabolic concentrators (CCPC). The determined values of diode reverse saturation current, combined series resistance and shunt resistance were similar to those of monocrystalline PV cell/modules in our previous publications. The model may be applicable to performance prediction of multi-junction CPV cells in the future

Travel, tourism, climate change and behavioral change: travelers’ perspectives from a developing country, Nigeria

While studies have examined people's understanding of climate change and its relationship to tourism, these focus largely on developed country populations. Much future tourism growth will come from developing countries following economic development; often countries where climate change will be strongly felt. Do tourists from developing countries have the same knowledge gaps about travel, tourism, and climate change as in the developed world? Will behavioral change policies be successful in encouraging more environmentally friendly approaches to climate change and tourism in developing countries? This paper presents findings from 20 in-depth interviews with active Nigerian tourists, analyzing their understanding of climate change, the links known, or not, between their travel and climate change, and their willingness to change their tourism patterns. Understanding of climate change was limited and there was conceptual confusion. Participants did not view their own travel as a cause of climate change and many were embedded in air travel practice. Participants were unwilling to change their tourism patterns to reduce their contribution to climate change. Significant structural barriers limit low carbon tourism travel in Nigeria (and other developing countries), including reliability, availability safety, and speed. Behavioral change will be difficult to achieve

Investigating the role of metapleural glands in social immunity and the role of co-founding in pathogen resistance in Messor barbarus

The risk of pathogen infection due to increased within-group transmission is theorised to be a major potential cost of group-living and eusociality. Many eusocial insects have evolved defence mechanisms to mitigate this risk and mount collective defences against pathogens. Social immunity describes the behaviours which are used to minimise pathogen spread within a colony, such as allo-grooming and waste management. Additionally, ants have developed chemical defences, such as the antimicrobial substance produced by the metapleural gland. This thesis investigated how the availability of metapleural glands and social immunity affect the survival probability of Messor barbarus and their response to an entomopathogenic fungus, Metarhizium brunneum. The results showed that the presence of fungal spores or Triton X on the cuticle increased self-grooming, and in the control treatment, an ant groomed for a longer period of time if they had a blocked gland. There was no difference in allo-grooming between individuals. Additionally, there was a high mortality of ants exposed to M. brunneum. More experiments are required to see whether the behaviours explored in this thesis are important or not in modulating the efficacity of the metapleural gland. There could be some other mechanism, potentially passive, involved in how the metapleural gland protects the ants from disease. Colony-founding queens do not have access to the colony-wide defensive system, and new colonies suffer high rates of mortality. In a number of eusocial insects, queens join together and co-found a colony collectively. This thesis investigated how being exposed to M. brunneum and group type affects the founding of new colonies. The results showed that exposed single queens and unexposed previously paired queens produced the highest number of brood and adults comparatively. These findings could support a newly discovered phenomenon called “hygienic cannibalism” where a queen will reinvest nutrients back into egg production from eating infected larvae. The presence of an unrelated queen could be viewed as interacting with a foreign substance, as being exposed to either another queen or a pathogen produced a large number of brood and adults. Exposed previously paired queens had the disadvantage of both an immune response and energy lost due to fighting so produced a small number of brood and adults in comparison

Volatile and glycosidically bound composition of Loureiro and Alvarinho wines

Composition of Loureiro and Alvarinho wines from the Vinhos Verdes region, respecting free volatile compounds as well as glycosidically bound aroma precursors, was exhaustively determined by GC-MS after adsorption on XAD-2 resin. On the whole, were identified and quantified 120 volatile compounds in the free fraction and 77 glycosidically bound compounds, belonging to C6-compounds, alcohols, fatty acids ethyl esters, esters of organic acids, acetates, monoterpenic alcohols, monoterpenic oxides and diols, C13-norisoprenoids, volatile phenols, volatile fatty acids and carbonyl compounds. Globally, the wines of the two cultivars present similar composition on volatiles. However, respecting varietal compounds, Loureiro wines are richer than Alvarinho ones with regard to C6-compounds and monoterpenic compounds, occurring the opposite for volatile phenols. It was also demonstrate that wines of both varieties may benefit the aroma reserve, present as glycoconjugates, as it is susceptible of being technologically explored. Linalool, Ho-trienol, α-terpineol, contributing with fruity and floral notes, and β-damascenone mostly for Alvarinho, confering tropical fruit notes, are the varietal compounds which may particularly influence the aroma of these wines. Respecting fermentative compounds, Alvarinho is also particularly rich in fatty acids ethyl esters related to lipid metabolism and acetates of fusel alcohols, which can provide it a fruity character; Loureiro contains higher levels of esters of organic acids and 2-phenylethanol, conferring fruity and floral notes. Sensory analysis agree with chemical analyses showing a pronounced tree and tropical fruit character for Alvarinho wines while Loureiro wines present more intense citrus fruit notes.Centre of Biological Engineering of Universidade do Minho; Estação Vitivinícola Amândio Galhano (EVAG); Solar de Serrade; EVAG; Comissão de Viticultura da Região dos Vinhos Verdes

Investigating the role of metapleural glands in social immunity and the role of co-founding in pathogen resistance in Messor barbarus

The risk of pathogen infection due to increased within-group transmission is theorised to be a major potential cost of group-living and eusociality. Many eusocial insects have evolved defence mechanisms to mitigate this risk and mount collective defences against pathogens. Social immunity describes the behaviours which are used to minimise pathogen spread within a colony, such as allo-grooming and waste management. Additionally, ants have developed chemical defences, such as the antimicrobial substance produced by the metapleural gland. This thesis investigated how the availability of metapleural glands and social immunity affect the survival probability of Messor barbarus and their response to an entomopathogenic fungus, Metarhizium brunneum. The results showed that the presence of fungal spores or Triton X on the cuticle increased self-grooming, and in the control treatment, an ant groomed for a longer period of time if they had a blocked gland. There was no difference in allo-grooming between individuals. Additionally, there was a high mortality of ants exposed to M. brunneum. More experiments are required to see whether the behaviours explored in this thesis are important or not in modulating the efficacity of the metapleural gland. There could be some other mechanism, potentially passive, involved in how the metapleural gland protects the ants from disease. Colony-founding queens do not have access to the colony-wide defensive system, and new colonies suffer high rates of mortality. In a number of eusocial insects, queens join together and co-found a colony collectively. This thesis investigated how being exposed to M. brunneum and group type affects the founding of new colonies. The results showed that exposed single queens and unexposed previously paired queens produced the highest number of brood and adults comparatively. These findings could support a newly discovered phenomenon called “hygienic cannibalism” where a queen will reinvest nutrients back into egg production from eating infected larvae. The presence of an unrelated queen could be viewed as interacting with a foreign substance, as being exposed to either another queen or a pathogen produced a large number of brood and adults. Exposed previously paired queens had the disadvantage of both an immune response and energy lost due to fighting so produced a small number of brood and adults in comparison

The PHENIX Experiment at RHIC

The physics emphases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed. The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program available at http://www.rhic.bnl.gov/phenix

Time of admission to the PICU and mortality

Objectives: To evaluate for any association between time of admission to the PICU and mortality. Design: Retrospective cohort study of admissions to PICUs in the Virtual Pediatric Systems (VPS, LLC, Los Angeles, CA) database from 2009 to 2014. Setting: One hundred and twenty-nine PICUs in the United States. Patients: Patients less than 18 years old admitted to participating PICUs; excluding those post cardiac bypass. Interventions: None. Measurements and Main Results: A total of 391,779 admissions were included with an observed PICU mortality of 2.31%. Overall mortality was highest for patients admitted from 07:00 to 07:59 (3.32%) and lowest for patients admitted from 14:00 to 14:59 (1.99%). The highest mortality on weekdays occurred for admissions from 08:00 to 08:59 (3.30%) and on weekends for admissions from 09:00 to 09:59 (4.66%). In multivariable regression, admission during the morning 06:00-09:59 and midday 10:00-13:59 were independently associated with PICU death when compared with the afternoon time period 14:00-17:59 (morning odds ratio, 1.15; 95% CI, 1.04-1.26; p = 0.006 and midday odds ratio, 1.09; 95% CI; 1.01-1.18; p = 0.03). When separated into weekday versus weekend admissions, only morning admissions were associated with increased odds of death on weekdays (odds ratio, 1.13; 95% CI, 1.01-1.27; p = 0.03), whereas weekend admissions during the morning (odds ratio, 1.33; 95% CI, 1.14-1.55; p = 0.004), midday (odds ratio, 1.27; 95% CI, 1.11-1.45; p = 0.0006), and afternoon (odds ratio, 1.17; 95% CI, 1.03-1.32; p = 0.01) were associated with increased risk of death when compared with weekday afternoons. Conclusions: Admission to the PICU during the morning period from 06:00 to 09:59 on weekdays and admission throughout the day on weekends (06:00-17:59) were independently associated with PICU death as compared to admission during weekday afternoons. Potential contributing factors deserving further study include handoffs of care, rounds, delays related to resource availability, or unrecognized patient deterioration prior to transfer

AD51B in Familial Breast Cancer

Common variation on 14q24.1, close to RAD51B, has been associated with breast cancer: rs999737 and rs2588809 with the risk of female breast cancer and rs1314913 with the risk of male breast cancer. The aim of this study was to investigate the role of RAD51B variants in breast cancer predisposition, particularly in the context of familial breast cancer in Finland. We sequenced the coding region of RAD51B in 168 Finnish breast cancer patients from the Helsinki region for identification of possible recurrent founder mutations. In addition, we studied the known rs999737, rs2588809, and rs1314913 SNPs and RAD51B haplotypes in 44,791 breast cancer cases and 43,583 controls from 40 studies participating in the Breast Cancer Association Consortium (BCAC) that were genotyped on a custom chip (iCOGS). We identified one putatively pathogenic missense mutation c.541C>T among the Finnish cancer patients and subsequently genotyped the mutation in additional breast cancer cases (n = 5259) and population controls (n = 3586) from Finland and Belarus. No significant association with breast cancer risk was seen in the meta-analysis of the Finnish datasets or in the large BCAC dataset. The association with previously identified risk variants rs999737, rs2588809, and rs1314913 was replicated among all breast cancer cases and also among familial cases in the BCAC dataset. The most significant association was observed for the haplotype carrying the risk-alleles of all the three SNPs both among all cases (odds ratio (OR): 1.15, 95% confidence interval (CI): 1.11–1.19, P = 8.88 x 10−16) and among familial cases (OR: 1.24, 95% CI: 1.16–1.32, P = 6.19 x 10−11), compared to the haplotype with the respective protective alleles. Our results suggest that loss-of-function mutations in RAD51B are rare, but common variation at the RAD51B region is significantly associated with familial breast cancer risk