The distribution of chilled water flow rate in terminal unit is a major factor used to evaluate the performance of central air conditioning unit. In this work, a theoretical chilled water distribution in the terminal units has been studied to predict the optimum heat performance of terminal unit. The central Air-conditioning unit model consists of cooling/ heating coil (three units), chilled water source (chiller), three-way and two-way valve with bypass, piping network, and pump. The term of optimization in terminal unit ingredient has two categories, the first is the uniform of the water flow rate representing in statically permanents standard deviation (minimum value) and the second category is the maximum heat transfer rate from all terminal units. The hydraulic and energy equations governing the performance of unit solved with the aid of FORTRAN code with considering the following parameters: total water flow rate, chilled water supply temperature, and variable valve opening. It was found that the optimum solution of three-way valve case at 8°C water supply temperature, 0.12 kg/s total water flow rate and valve opening order (valve 1: 100%, valve 2: 100% and valve 3: 75%) with total heat rate (987.92 Watt) and standard deviation (1.181E-3). Also, for the two-way valve case the results showed that the optimum condition at 8°C water supply temperature, 0.12 kg/s total water flow rate and valve opening order (valve 1: 75%, valve 2: 75% and valve 3: 50%) with total heat rate and standard deviation (717Watt) and (5.69E-4) respectively.
Free radical formation in heme proteins is recognized as a factor in mediating the toxicity of many chemicals. The present study was designed to evaluate the dose-response relationship of the free radical scavenging properties of pentoxifylline in nitrite-induced Hb oxidation. Different concentrations of pentoxifylline were added at different time intervals of Hb oxidation in erythrocytes lysate, and formation of methemoglobin (MetHb) was monitored spectrophotometrically. The results showed that in this model, pentoxifylline successfully attenuates Hb oxidation after challenge with sodium nitrite; this protective effect was found to be not related to the catalytic stage of Hb oxidation, th
... Show MoreBackground: Doxorubicin is considered one of the most effective anticancer drugs, yet it is use is limited by its side effect mediated by the generation of reactive oxygen species. Omega-7, an antioxidant has shown to have a cardioprotective effect.
Aim of the study: evaluate a possible protective effect of omega-7 against doxorubicin-induced cardiotoxicity in male rats.
Methods: twenty-eight male rats were divided into 4 groups (7 for each group). Group 1 (Negative control): healthy animals received normal saline orally as the vehicle for eight successive days and were sacrificed on day 9. Group 2 (positive control): animals that r
... Show MoreThe Providence of the Rosaly's family to the Intellectual Movement in Yemen
Background: Cigarette smoking is an important risk factor that has a clear strong association with the prevalence and severity of chronic periodontitis (CP). Salivary biochemical parameters may be affected by both smoking and CP together. Materials and methods: Eighty systematically healthy male patients were included in this study. They were grouped based on their periodontal and smoking status. Unstimulated whole saliva (UWS) was collected from all subject. Salivary flow rate (FR) was measured during sample collection. Parameters such as salivary pH, total protein (TP), albumin (Alb), total fucose (TF), protein bound fucose (PBF) and C-reactive protein (CRP) were estimated. Results: Salivary flow rate was not altered regarding to smoking
... Show MoreBack ground: One out of six children in the
world today is involved in child labor, doing
work that is damaging to his or her mental,
physical and emotional development.
Objective: Assessment of some health
problems among the studied working children.
Method; A cross-sectional study was
conducted in Al Amen Primary Health Care
(PHCC) during the period from January to
August 2009, a sample of 6048 children were
selected randomly(3218girls and2866 boys age
between 5-17 years ) and interviewed to collect
information using a structured questionnaire
form, information related to different aspects
of child labor prevention were included in the
form as well as a general medical examination
and lab
Background: the condition of hallux valgus is considered as the most common deformities affecting females more than males, characteristically manifested as lateral deviation of the big toe and widening of first and second inter -metatarsal angle with a deformity of second toe in some severe cases. Objective: to make a radiological and clinical assessment of two surgical methods of osteotomy used in treatment of hallux valgu and to compare between them: first one is the distal dome osteotomy, and second one is a distal wedge metatarsal osteotomy. Patients and methods: a total of 36 feet of 28 patients suffer from hallux valgus, with mean age of 50.3 years were included in this study, followed for 6- 30 months ( mean follow-up of 8.8 months).
... Show MoreBackground: Restoration of the gingival margin of Class II cavities with composite resin continues to be problematic, especially where no enamel exists for bonding to the gingival margin. The aim of study is to evaluate the marginal leakage at enamel and cementum margin of class II MOD cavities using amalgam restoration and modern composite restorations Filtek™ P90, Filtek™ Z250 XT (Nano Hybrid Universal Restorative) and SDR bulk fill with different restoratives techniques. Materials and method: Eighty sound maxillary first premolar teeth were collected and divided into two main groups, enamel group and cementum group (40 teeth) for each group. The enamel group was prepared with standardized Class II MOD cavity with gingival margin (1 m
... Show MoreSewage sludge samples were collected from Al-rasafa and Al-karkh refinement stations which represent the main stations of Baghdad city. Samples were collected from all treatment stages: before, after, and during refinement processes. The High Purity Germanium Coaxial Detector system with energy resolution 1.8 keV for energy line 1333 keV of Co – 60 radioactive sources was used to measure radioactivity from both natural and artificial sources. GENIE – 2000 analysis the results statistically and qualitatively. The results showed that all sewage sludge samples exhibited natural radioactive level and sometimes less than the international regular standards, but Al–Karkh station showed increment in radioactive levels than Al– Rasa
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