Moisture condensation on building envelopes in differential ventilated spaces in the tropics: quantitative assessment of influencing factors

Ventilation systems play a significant role in maintaining the indoor thermal and hygric balance. Nevertheless, the systems had been implicated to result in many problems. In the tropical climate, especially for energy efficiency purposes, building spaces are operated with differential ventilation. Such spaces operate on 24-hrs basis, some on 8-hrs while others are either naturally ventilated or served with mechanical supply-exhaust fan systems with non-conditioned outdoor air. This practice had been found to result in condensation problems. This study involves a quantitative appraisal of the effect of operative conditions and hygrothermal quality of building envelopes on condensation risk. The in-situ experiment is combined with an analytical approach to assessing the hygrothermal quality of building envelopes in a tropical climate building under differential ventilation between adjacent spaces. The case-studied building is with a known history of condensation and associated damages including mould growth. The microclimate measurement and hygrothermal performance of the wall and floor against condensation and mould growth risks had been previously reported elsewhere. As a step further, the present study evaluates the effects of various envelope insulation types and configurations together with the HVAC cooling set-points on envelope hygrothermal performance. The results revealed that overcooling the air-conditioned side increases condensation risk on the non-air-conditioned side of the envelopes. The envelopes failed criteria for surface condensation at existing operative conditions irrespective of envelope hygrothermal quality improvements. However, the envelope performed well at improved cooling operative conditions even at existing envelope hygrothermal quality. It is, therefore, important to ascertain the envelope hygrothermal quality as well the cooling operative conditions while embarking on energy efficiency operations in mechanical ventilation systems under differential ventilation

Costunolide prevents renal ischemia-reperfusion injury in rats by reducing autophagy, apoptosis, inflammation, and DNA damage

Objective(s): Renal ischemia-reperfusion (I/R) is a vital health condition leading to acute kidney injury. Costunolide (COST) is an actively used molecule clinically for its anti-inflammatory, antioxidant, and immunomodulatory properties. In the present study, we searched for the possible protective effects of COST against renal ischemia/reperfusion (I/R) injury in rats.Materials and Methods: We established a renal I/R rat model. We divided forty rats into four groups: group I (sham), group II (I/R), group III (I/R+COST 5 mg/kg), and group IV (I/R+COST 10 mg/kg). We collected blood, kidney, and lung samples for analysis. Results: COST administration performed anti-oxidant and anti-inflammatory activity by reducing oxidant parameters and proinflammatory cytokine levels. COST alleviated DNA damage through declining 8-hydroxydeoxyguanosine (8-OHdG) levels. In addition, COST diminished tubular damage and inflammation by reducing kidney injury molecule-1 (KIM-1) production. COST administration also ameliorated apoptosis and autophagy by decreasing caspase-3 and microtubule-associated protein light chain 3B (MAPLC3, LC3B) expression.Conclusion: COST demonstrated protective effects against renal I/R-induced injury

IS THERE A SEASONAL VARIATION IN DRUG VEIN THROMBOSIS HOSPITAL ADMISSIONS?

Amaç: Çeşitli kardiyovasküler hastalıkların oluşumunda mevsimlerin belirgin etkisi olduğu görülmüştür. Derin ven trombozu için mevsimsel ilişki konusunda yapılan çalışmaların sonuçları tartışmalıdır. Yaptığımız çalışmanın amacı derin ven trombozu gelişiminde mevsimsel farklılıkların yanı sıra komorbid risk faktörlerinin muhtemel etkisinin araştırılmasıdır. Gereç ve yöntem: Ocak 1997- Temmuz 2008 arasında başvuran 398 derin ven trombozu tanısı konulup, izlenen hastanın mevsimsel farklılık açısından alt gruplara ayrılarak retrospektif olarak incelemesi yapılmıştır. Bulgular: Mevsimsel analiz sonucu derin ven trombozu görülme sıklığı ilkbaharda % 31, yaz aylarında %19, sonbaharda %24 ve kış %26 olarak tespit edildi (p=0,024). Aylara göre yapılan incelemede, en düşük görülme oranı % 4,8 ile Temmuz ayında olurken, en yüksek görülme oranı %11,3 ile Mayıs ve Mart aylarındaydı. Kronobiyolojik analiz sonuçları mevsimsel değişimin istatistiksel anlamı olduğunu gösterdi (p=0,043). Sonuç: Yaptığımız çalışma hastanemizde derin ven trombozu ile yatırılan olguların özellikle yaz aylarında daha azaldığını, ilk bahar aylarında ise arttığını saptadık. Sıcaklık açısından soğuk havanın hüküm sürdüğü ayların ve buna bağlı hiperkoagülbilitenin yüksek risk yaratan bir durum olabileceği düşünülmektedir. Objective: The occurence of several adverse cardiovascular events shows definite seasonal patterns. The temporal pattern for the data concerning deep vein thrombosis are not conclusive. The aim of our study was to investigate whether a seasonal variation exists also deep vein thrombosis together with possible influence of different comorbid risk factors. Material and method: We observed 398 consecutive cases of deep vein thrombosis from January 1997 to July 2008. The total sample was divided into subgroups by seasonal variation. All cases were investigated retrospectively. Results: Seasonal analysis showed that deep vein thrombosis occurence was %31 in spring, %19 in summer, %24 in autumn and %26 in winter (Ï=0.024). In analysis according to months revealed the most reduction in July with %4.8, with a peak in May and March %11.3. Chronobiological analysis yielded a statistically significant difference in seasonal variation (p=0.043). Conclusions: This study shows the existence of a highly significant pattern in the occurence of deep vein thrombosis, characterized by a spring peak, decrease in summer. Thus colder months and relative hypercoagulability could be considered a supplementary high risk condition

An experimental exergetic comparison of four different heat pump systems working at same conditions: As air to air, air to water, water to water and water to air

In this study, we designed a multifunctional heat pump system using just one scroll compressor and which can be run in four different modes, namely air to air, air to water, water to water and water to air, in order to make an experimental energetic and exergetic performance comparison. Experimental system consists of two condensers and two evaporators and uses R22 as working fluid. One of the evaporators and condensers uses water and the others use air as heat source/sink. Heating capacities of four heat pump types are equal to each other. It is realized by adjusting the mass flow rate and temperature level of external fluid of condenser. Results show that the heat pump unit which has the maximum COP (coefficient of performance) value is water to air type with 3.94 and followed by water to water type with 3.73, air to air type with 3.54 and air to water type with 3.40. Ranking of four heat pump types with respect to their mean exergy efficiency is as follows; water to air type with 30.23%, air to air type with 30.22%, air to water type with 24.77% and water to water type with 24.01%. Exergy destruction rates of the systems were investigated in this study and the results revealed that the heat pump type which has the maximum exergy destruction is air to air type with 2.93kW. The second highest one is air to water type with 2.84kW. The third highest one is water to air type with 2.64kW and last one is water to water type with 2.55kW. It is understood that the temperature of the evaporator external fluid affects the exergetic efficiency of the system more than the mass flow rate. In contrast to the previous, the dominant parameter which has more important effect on the exergy destruction of the heat pump unit is the mass flow rate of evaporator external fluid. © 2013 Elsevier Ltd

Investigation of the relationship between the mineral shape properties and destruction specific energy in granitic rocks [Granitik kayaçlarda mineral şekil özellikleri ile spesifik deformasyon enerjisi arasindaki ilişkinin araştirilmasi]

One of the mechanical property of rocks is destruction specific energy that estimated from the area (integral) under the stress-strain curve in unconfined compression test. The minerals in the rocks are effective on the mechanical properties of the rocks. In this study, the relation between destruction specific energy and mineral shape properties were investigated. The unconfined compressive tests were performed on nine different rock samples and the destruction specific energy values were estimated with calculating the area (integral) under the stress-strain curve for each rock sample. The texture coefficient approach was used for determining of the mineral shape properties and the texture coefficient values were calculated for each rock sample. The results were analyzed with using linear regression analyze method and a strong relation was found between destruction specific energies and the texture coefficients of rocks

The relation of collector and storage tank size in solar heating systems

The most popular method to benefit from the solar energy is to use solar water heating systems since it is one of the cheapest way to benefit from the solar energy. The investment cost of a solar water heating system is very low, and the maintenance costs are nearly zero. Using the solar energy for solar water heating (SWH) technology has been greatly improved during the past century. A storage tank is used in many solar water heating systems for the conservation of heat energy or hot water for use when some need it. In addition, domestic hot water consumption is strongly variable in many buildings. It depends on the geographical situation, also on the country customs, and of course on the type of building usage. Above all, it depends on the inhabitants' specific lifestyle. For that reason, to provide the hot water for consumption at the desirable temperature whenever inhabitants require it, there must be a good relevance between the collectors and storage tank. In this paper, the optimum sizes of the collectors and the storage tank are determined to design more economic and efficient solar water heating systems. A program has been developed and validated with the experimental study and environmental data. The environmental data were obtained through a whole year of operation for Erzurum, Turkey. © 2012 Elsevier Ltd. All rights reserved