Nanofluid suspensions as heat carrier fluids in single U-tube borehole heat exchangers

The borehole heat exchanger (BHE) is a critical component to improve energy efficiency and decreasing environmental impact of ground-source heat pump systems. The lower thermal resistance of the BHE results in the better thermal performance and/or in the lower required borehole length. In the present study, effects of employing a nanofluid suspension as a heat carrier fluid on the borehole thermal resistance are examined. A 3D transient finite element code is adopted to evaluate thermal comportment of nanofluids with various concentrations in single U-tube borehole heat exchangers and to compare their performance with the conventional circuit fluid. The results show, in presence of nanoparticles, the borehole thermal resistance is reduced to some extent and the BHE renders a better thermal performance. It is also revealed that employing nanoparticle fractions between 0.5% and 2 % are advantageous in order to have an optimal decrement percentage of the thermal resistance

A new estimate of sand and grout thermal properties in the sandbox experiment for accurate validations of borehole simulation codes

Ground-coupled heat pumps usually employ fields of borehole heat exchangers (BHEs), which must be designed by suitable models. In order to validate a BHE model, it is advisable to compare the computation results with experimental data. A well-known data set was provided by Beier et al. (Geothermics 2011, 40) through a laboratory model usually called “sandbox”. Several authors proposed estimates of the thermal properties of the sandbox grout and sand. In this paper, we present a new estimate of those properties, obtained by means of 2D finite-element simulations that consider all the details of the experimental setup, including the thin aluminum pipe at the BHE boundary. Our results show that the measured temperatures in the fluid and in the sand can be reproduced very accurately by considering thermal conductivities 0.863 W/(mK) for the grout and 3.22 W/(mK) for the sand, volumetric heat capacities 4.6 MJ/(m3K) for the grout and 3.07 MJ/(m3K) for the sand, and a slightly enhanced heat capacity of the water contained in the BHE. The 2D simulations are validated by comparison with an analytical solution and by 3D simulations

Numerical Analysis on the Optimisation of Thermal Comfort Levels in an Office Located inside a Historical Building

The present study examines the possibility of thermal comfort optimisation inside an office room where, due to historical heritage, it is possible to modify neither the energetic characteristic of the envelope nor the position of the inlet air vents. The distribution of global and local thermal comfort indices is evaluated in both heating and cooling conditions by establishing a computational fluid dynamics (CFD) model validated against experimental data. The obtained results demonstrate a striking asymmetry of the air velocity and temperature distribution due to the low energy efficiency of the building. In heating mode, the predicted mean vote (PMV) values were improved if the discharged air from the fan coil was at its maximal velocity. However, at the same time, the vertical air temperature gradient increased by around 0.5 C in each working station. In the cooling condition, in the absence of the solar radiation, the minimal air-flow rate satisfied the acceptable range of the draught rate (DR), whereas in the presence of a solar load, it could not meet the required cooling load in all positions, leading to higher floor temperature. The findings of this study allow for identifying and rearranging the optimal position of working stations in terms of thermal comfort

Association between colorectal cancer and Fusobacterium nucleatum and Bacteroides fragilis bacteria in Iranian patients: a preliminary study

Background and aim: Recent studies have proposed that commensal bacteria might be involved in the development and progression of gastrointestinal disorders such as colorectal cancer (CRC). Therefore, in this study, the relative abundance of Fusobacterium nucleatum, Bacteroides fragilis, Streptococcus bovis/gallolyticus, and Enteropathogenic Escherichia coli (EPEC) in CRC tissues, and their association with clinicopathologic characteristics of CRC was investigated in Iranian patients. Moreover, the role of these bacteria in the CRC-associated mutations including PIK3CA, KRAS, and BRAF was studied. Method: To these ends, the noted bacteria were quantified in paired tumors and normal tissue specimens of 30 CRC patients, by TaqMan quantitative Real-Time Polymerase Chain Reaction (qPCR). Next, possible correlations between clinicopathologic factors and mutations in PIK3CA, KRAS, and BRAF genes were analyzed. Results: In studied samples, B. fragilis was the most abundant bacteria that was detected in 66 and 60 of paired tumor and normal samples, respectively. Furthermore, 15 of the B. fragilis-positive patients were infected with Enterotoxigenic B. fragilis (ETBF) in both adenocarcinoma and matched adjacent normal samples. F. nucleatum was also identified in 23 of tumors and 13 of adjacent normal tissue samples. Moreover, the relative abundance of these bacteria determined by 2-�CT was significantly higher in CRC samples than in adjacent normal mucosa (p < 0.05). On the other hand, our findings indicated that S. gallolyticus and EPEC, compared to adjacent normal mucosa, were not prevalent in CRC tissues. Finally, our results revealed a correlation between F. nucleatum-positive patients and the KRAS mutation (p = 0.02), while analyses did not show any association between bacteria and mutation in PIK3CA and BRAF genes. Conclusion: The present study is the first report on the analysis of different bacteria in CRC tissue samples of Iranian patients. Our findings revealed that F. nucleatum and B. fragilis might be linked to CRC. However, any link between gut microbiome dysbiosis and CRC remains unknown. © 2021, The Author(s)

Estimating utility value for female genital mutilation

Background: Female genital mutilation/cutting (FGM/C) is a clear violation of women's rights and can have adverse and irreversible health effects as well. Worldwide, more than 200 million women and girls have undergone FGM/C. Utility value of FGM/C has not been estimated yet, so we designed this study to extract the health utility value of FGM/C for the first time in the world. Methods: In a cross-sectional study in Iran, 125 girls and women who underwent FGM/C procedure were examined by the trained midwives in order to determine its type. In addition, a questionnaire was completed for identifying the socio-demographic factors and extracting the health utility of these individuals. Health utility was measured using Time Trade-off method and also to determine the effects of the socio-demographic factors on the health utility a two-limit censored regression model was applied. Results: The mean and median of the health utility of women with FGM/C were 0.971 (SE: 0.003) and 0.968 (IQR: 1-0.95), respectively. Number of non-Traders was 58 (46.4) who reported perfect health utility. However, the mean of health utility among traders was 0.946 (SE: 0.002). Only type 1 (Clitoridectomy) and type 2 (Excision) FGM/C were seen in this study. Women with Type 1 FGM/C had significantly lower health utility value (Mean: 0.968, Median: 0.957) than their type 2 counterparts (Mean: 0.987, Median: 1.00). Moreover, women in the age group of 31-45 years (Mean: 0.962, Median: 0.956), single (Mean: 0.950, Median: 0.954), divorced (Mean: 0.951, Median: 0.950), employed (Mean: 0.959, Median: 0.956), and with supplementary insurance (Mean: 0.962, Median: 0.950) had significantly lower health utility than their counterparts. Conclusion: FGM/C affects physical and psychological well-being of these individuals, resulting in a lack of personal and marital satisfaction, which ultimately leads to a 3 reduction in their health related quality of life. Therefore, preventing from this practice is very important and should be considered by health system policy makers more than before. © 2020 The Author(s)

Thermal performance of the vertical ground heat exchanger with a novel elliptical single U-tube

Ground-Coupled Heat Pumps (GCHPs) are known as a promising technology for building climatization and domestic hot water production. The main concern to employ these systems in urban areas is their high drilling and initial cost. This cost could be rebated by lowering the borehole thermal resistance and by shortening the borehole depth. In the present paper, a novel and simple design of the Ground Heat Exchanger (GHE), namely the vertical GHE with an elliptical U-tube, is proposed to improve thermal performance of GCHP systems. To prove that; a series of 3D finite element simulations are performed to study the thermal comportment of elliptical U-tubes and to compare their performance with typical single U-tubes. A dimensionless shape factor \u3b3 is introduced to evaluate effect of the elliptical U-tube geometry on thermal performance of the GHE. Furthermore, influential parameters on thermal performance of elliptical U-tubes are investigated and the decrement percentage of the borehole thermal resistance, with reference to the typical U-tube, are compared for each parameter. The results show that elliptical U-tubes could enhance heat transfer to significant extent and could decrease the borehole thermal resistance by more than 17 %, compared with typical single U-tubes. It is shown that the higher value of the shape factor \u3b3 leads to the better heat transfer enhancement. It is concluded that elliptical U-tubes are able to decrease the borehole thermal resistance and to boost the coefficient of performance (COP) of GCHP systems

Nasoalveolar Molding: A new Method for Cleft Lip and Palate Rehabilitation

Introduction: Cleft lip and palate is a congenital anomaly occurring in 3 in 1000 live birth. One the major concern in this patient is about cleft gap and its surgical problems. Several surgical and non-surgical procedures have been done to decrease this gap. They aimed to achieve the more esthetic results as well as feeding success. Nasoalveolar Molding (NAM) is a new method for reshaping nasal and alveolar bones, presurgically. Matsuo et al described that auricular cartilage could be molded permanently when treatment was done within 6 weeks of life. High levels of maternal estrogen in the fetal circulation can triggers hyaluronic acid which can alter the cartilage, ligament and connective tissue elasticity.Estrogen level continue to drop after 6 weeks of age. This concept was applied for the correction of nasal deformities in cleft lip patients. Nasolaveolar molding may stimulate immature nasal chondroblasts and produce interstitial expansion.   Aims of Nasoalveolar Molding: a. Active molding and repositioning of the deformed nasal cartilages and alveolar processes. b. Appropriate Lengthening of the columellac. Better bone healing after surgey due to reducing the gaped. Reduces the need for secondary alveolar bone grafts. Correction of lip position with minimal scarf. Reducing hospital stay for nasal esthetic surgeryg. Better weight gain in early infancy   Conclusion: Management of cleft lip and palate has been changed with more emphasis on the nasal and alveolar molding prior to the primary lip repair. This method reduces the number reconstructive surgeries  for the purpose of esthetics as well as may cause better feeding in early infancy.   Keywords: Cleft Lip and Palate, Infant Orthopedics, Nasal Molding