Environmental design solutions for existing concrete flat roofs in low-cost housing to improve passive cooling in western Mexico

The development of real estate in Mexico has largely ruled out the comfort of users that focused on economic matters and made it difficult to make substantial progress in adopting measures to improve indoor environmental quality. Current research projects in Mexico found that roof construction in low-cost housing struggles to meet the requirements of the indoor climate. Passive cooling strategies are techniques to control heat gain and heat dissipation in buildings to maximise the comfort and health of building users while minimising energy use. Passive cooling systems recognize climate conditions and utilise renewable sources of energy such as the sun and wind to provide cooling and ventilation. Therefore, this study aims to develop a green and sustainable solution for existing concrete flat roofs with no major interventions and investments to save energy. The design of a passive device was tested to assess its effectiveness to protect flat roofs from shortwave radiation and to allow for heat dissipation in Mexican buildings. The study used a quantitative approach based on experiments and simulation tests to evaluate design efficiency. The results showed that a perforated device with an opening percentage of 88% and a cavity of 0.05m between the roof and the device provided effective protection. Also, the device with blinds of 45° showed lower operative temperatures within a range of mean values between 0.8°C and 0.9°C compared to a roof with a full shade cover in the hot and humid season. However, the perforated device with blinds of 90° in black colour delivered the best performance compared to other models and recorded a mean value of 1.13°C in the hot sub-humid season. The results revealed the efficiency of the proposed device that can be observed within different geometric configurations, surface properties as well as the use of the nocturnal radiative cooling potential in blocking solar radiation in Mexican buildings

Effects of Raspberry Fruit (Rubus anatolicus (focke) foke ex hausskn) Hydroalcoholic Extract on Blood Glucose, Lipid Profile and Oxidative Stress Markers in Streptozotocin-diabetic Rats

Background and Objectives: Diabetes is one of the most common endocrine disorders worldwide. Rubus anatolicus is rich in polyphenolic compounds that can protect individual from various chronic diseases such as diabetes. This study was carried out to investigate effects of hydroalcoholic extract of raspberry fruit Rubus anatolicus (focke) on blood glucose levels, lipid profiles and oxidative stress markers in streptozotocin-induced diabetic rats. Materials & Methods: In this study, 32 male Wistar rats weighing 150�200 g were used. Diabetes was induced in rats using streptozotocin and diabetic animals were then treated with raspberry fruit hydroalcoholic extract for 14 days. Rats were anesthetized using xylazine and ketamine mixture and sacrificed. Then, whole blood samples were collected from the animal hearts to assess their serum glucose levels, lipid profiles and oxidative markers. The p-value < 0.05was considered as significant. Results: Results of the present study showed that raspberry fruit extracts significantly decreased serum glucose levels, triglycerides, cholesterol, low-density lipoproteins and malondialdehyde levels in diabetic rats, compared to the diabetic control rats (p < 0.05). Moreover, serum low-density lipoproteins level, total antioxidant capacity and superoxide dismutase activity significantly increased in diabetic rats, compared to diabetic control rats (p < 0.05). Conclusion: The present study showed that fruit extract raspberry included good effects on blood glucose levels, lipid profiles and oxidative stress conditions in diabetic rats. © 2022, National Nutrition and Food Technology Research Institute. All rights reserved

Frequency-dependent electrophysiological properties of concealed slow pathway of isolated rabbit atrioventricular node preparation after fast pathway ablation in a functional model

Introduction: Intranodal pathways of atrioventricular (AV) node play a vital role in the delay of conduction time in response to various atrial inputs. The present study was aimed to determine the frequency-dependent electrophysiological properties of concealed slow pathway according to a functional model of isolated rabbit atrioventricular node preparation after fast pathway ablation. Methods: Experiments were carried out in rabbit isolated heart AV-nodal preparations (N=8) by superfused/perfused mode. Extracellular recording was carried out from transitional cells of posterior and anterior extension of AV-node and upper part of atrium and its bundle. Unipolar silver electrode (100 μm) and direct voltage (100-110 V) was applied to create AV-nodal fast pathway ablation. Results: Minimum conduction time (AHmin) was significantly increased after fast pathway ablation (p<0.05). Fast pathway ablation had no significant impact on fatigue phenomenon but significantly reduced facilitation value (p<0.05). Rate-dependency properties of concealed slow pathway were explained according to functional nodal model. Conclusion: The mathematical functional model accurately simulated frequency-dependent electrophysiological properties of concealed slow pathway after fast pathway ablation, but some modifications are necessary for accurate prediction of nodal behavior in various cycle lengths and in arrhythmia. Concealed slow pathway may be considered as a potential electrophysiological substrate of fatigue and facilitation phenomenon

Preconditioning and anti-apoptotic effects of Metformin and Cyclosporine-A in an isolated bile duct-ligated rat heart

Despite all previous studies relating to the mechanism of cirrhotic cardiomyopathy (CCM), the role of cirrhosis on Ischemic Preconditioning (IPC) has not yet been explored. The present study strives to assess the cardioprotective role of IPC in bile duct ligated (BDL) rats as well as the cardioprotective role of Cyclosporin-A (CsA) and Metformin (Met) in CCM. Cirrhosis was induced by bile duct ligation (BDL). Rats� hearts were isolated and attached to a Langendorff Apparatus. The pharmacological preconditioning with Met and CsA was done before the main ischemia. Myocardial infarct size, hemodynamic and electrophysiological parameters, biochemical markers, and apoptotic indices were determined at the end of the experiment. Infarct size, apoptotic indices, arrhythmia score, and incidence of VF decreased significantly in the IPC group in comparison with the I/R group. These significant decreases were abolished in the IPC (BDL) group. Met significantly decreased the infarct size and apoptotic indices compared with I/R (BDL) and normal groups, while CsA led to similar decreases except in the level of caspase-3 and -8. Met and CsA decreased and increased the arrhythmia score and incidence of VF in the BDL groups, respectively. Functional recovery indices decreased in the I/R (BDL) and IPC (BDL) groups. Met improved these parameters. Therefore, the current study depicted that the cardioprotective effect of Met and CsA on BDL rats is mediated through the balance between pAMPK and apoptosis in the mitochondria. © 2020 Elsevier B.V