Comprehensive investigations of mixed convection of Fe-ethylene-glycol nanofluid inside an enclosure with different obstacles using lattice Boltzmann method.

In the present paper, nanofluid mixed convection is investigated in a square cavity with an adiabatic obstacle by using the Lattice Boltzmann method (LBM). This enclosure contains Fe-ethylene-glycol nanofluid and three constant temperature thermal sources at the left wall and bottom of the enclosure through a lateral wall. The fluid is incompressible, laminar, and Newtonian. The obtained results are presented in the constant Ra = 104 and a Pr = 0.71 for different Ri = 0.1, 1, and 10. The effects of the slope of the enclosure, volume fraction of nanoparticles [Formula: see text], the location of adiabatic obstacles, and nanoparticle diameter in the fluid are investigated on the value of heat transfer. A change in the attack angle of the enclosure leads to changes in the movement distance for fluid between hot and cold sources and passing fluid through case E, which affects the flow pattern strongly. In each attack angle, on colliding with an obstacle, the fluid heat transfers between two sources, which leads to uniform heat transfer in the enclosure. By increasing the velocity of the lid, the Richardson number decreases leading to improvement of the convective heat transfer coefficient and Nusselt number enhancement. The results so obtained reveal that by augmenting [Formula: see text] value the effect of Richardson number reduction can augment Nusselt number and the amount of absorbed heat from the hot surface. Consequently, in each state where a better flow mixture and lower depreciation of fluid velocity components, due to the penetration of lid movement and buoyancy force, occurs higher heat transfer rate is accomplished. Furthermore, it is shown that when Ri = 0.1, the effect of cavity angle is more important but when Ri = 10, the effect of the position of obstacle is more visible.

The effect of modified electrospun PCL-nHA-nZnO scaffolds on osteogenesis and angiogenesis.

Large bone defects treatment is one of the challenges in current bone tissue engineering approaches. Various strategies have been proposed to address this issue, among which, prevascularization by coculturing of angiogenic and osteogenic cells on the scaffolds can alleviate this problem. In the present study, modified fibrous scaffolds were prepared by electrospinning and subsequent ultrasonication of polycaprolactone (PCL) containing nano-hydroxyapatite (n-HA), with/without nano-zinc oxide (n-ZnO), and polyethylene oxide [PEO] as a sacrificial agent. The physical, mechanical, and chemical characteristics of the scaffolds were evaluated. The results showed the presence of n-ZnO, which in turn increased Young's module of the scaffolds from 5.5 ± 0.67 to 6.7 ± 1.77 MPa. Moreover, MTT, SEM, alkaline phosphatase (ALP) activity, chicken embryo chorioallantoic membrane (CAM) assay, and real-time RT-PCR were utilized to investigate the biocompatibility, cell adhesion and infiltration, osteoconductivity, angiogenic properties, and expression of osteogenic and angiogenic related genes. ALP assay showed that the highest enzyme activity was noted when the modified scaffolds containing n-ZnO were seeded with HUVEC:hBMSC at the cell ratio of 1:5. CAM assay showed induction of angiogenesis for the scaffolds containing n-ZnO. Real-time RT-PCR results showed significant upregulation of angiogenic related genes. Thus, the scaffolds containing n-ZnO may have great potential for osteogenesis and angiogenesis in tissue engineering applications.

Changes in the hemoglobin level after one unit of packed red blood cell transfusion in Intensive Care Unit patients.

BACKGROUND: Blood transfusion is essential in severely ill patients whose hemoglobin (Hb) levels are low, but there are some factors that inhibit optimal increase in Hb. The aim of this study was to evaluate the amount of increase in Hb levels after packed red blood cell (PRBC) transfusions in the Intensive Care Unit (ICU) patients and its related factors. MATERIALS AND METHODS: This cross-sectional study included 124 patients admitted to the ICU, and needed PRBC transfusion. Demographic information, Hb on the 1st day of admission, blood volume transfusions during the 7 days, and the 7th day of admission Hb level were extracted from patients' records. RESULTS: The average initial Hb level of patients was reported as 6.17 ± 1.43 g/dl, and after administrating PRBC (4.23 ± 1.87 units during 7 days), the Hb level was 8.09 ± 1.66 g/dl after 7 days (mean difference was 1.91 ± 1.93, t = 11.06, P < 0.001). No significant differences were found between change in Hb level in the terms of age, gender, underlying illness, body mass index, hospitalization history, fever, and duration of hospitalization (P > 0.05). However, the mean increased Hb level in hospitalized patients with internal disorders was the lowest (0.25 g/dl, P = 0.002). CONCLUSION: The results of our study showed that the increased Hb level based on one unit of received PRBC was low, especially in patients with internal. Therefore, based on high frequency of anemia in ICU patients and relative complications, physicians should pay attention to factors affecting Hb levels after PRBC transfusion such as medical history.