Increased Demand for Blood Transfusion in Cardiac Surgery: Simple but Unsolved Common Problem

Background: Despite the general concern about the safety of blood transfusion and mounting evidence exist for more restrictive practice; there is no national consensus guideline and uniformity of institutions for blood transfusion associated with coronary artery bypass graft surgery in Iran. The aim of this study is an assessment of current transfusion practice and compares it with one decade ago.Method: The authors retrospectively analyzed the data of all patients undergoing elective surgery (first time operation) during one year, in two different decade interval (2003 and 2015) in a tertiary heart center.Results: A total of 801 patients were evaluated and compared (n=249 in 2015, n=552 in 2003). There is a significant increase in use of blood transfusion in both operating room and at ICU than the last decade (60.6% vs. 42.4%, P<0.001, and 54.4% vs. 39.9%, P <0.001, respectively). The incidence of preoperative anemia was four times higher in patients who received transfusion, compared to those who did not, in both groups. With compared to the past, the patients are older, have less preoperative hematocrit, more diabetic, more need to intra-aortic balloon pump, shorter operation time, and less postoperative bleeding .Conclusion: With advanced knowledge about transfusion complications and conservative approach to transfusion practice, the need to blood transfusion is increased in current cardiac operations in our center, due to association of more co-morbidities

Low temperature synthesis of CaZrO3 nanoceramics from CaCl2–NaCl molten eutectic salt

CaZrO3 nanoceramics were successfully synthesized at 700 C using the molten salt method, and the effects of processing parameters, such as temperature, holding time, and amount of salt on the crystallization of CaZrO3 were investigated. CaCl2, Na2CO3, and nano-ZrO2 were used as starting materials. On heating, CaCl2–NaCl molten eutectic salt provided a liquid medium for the reaction of CaCO3 and ZrO2 to form CaZrO3. The results demonstrated that CaZrO3 started to form at about 600C and that, after the temperature was increased to 1,000C, the amounts of CaZrO3 in the resultant powders increased with a concomitant decrease in CaCO3and ZrO2 contents. After washing with hot distilled water, the samples heated for 3 h at 700C were single-phase CaZrO3 with 90–95 nm particle size. Furthermore, the synthesized CaZrO3 particles retained the size and morphology of the ZrO2 powders which indicated that a template mechanism dominated the formation of CaZrO3 by molten-salt method

THE EFFECT OF PROCESSING PARAMETERS ON SOL GEL SYNTHESIS OF β-SiC NANO POWDER

Mono dispersed nano SiC particles with spherical morphology were synthesized in this project by hydrolysis and condensation mechanism during sol gel processing. pH, temperature and precursor’s ratio considered as the main parameters which could influence particles size. According to DLS test results, the smallest size of particles in the sol (<5nm) was obtained at pH<4. It can be observed from rheology test results optimum temperature for achieving nanometeric gel is about 60 ˚C. The optimum pH values for sol stabilization was (2-5) determined by zeta potentiometery. Si 29NMR analysis was used in order to get more details on final structure of gel powders resulted from initial sol. X-ray diffraction studies showed sythesized powder consists of β-SiC phase. Scanning electron microscopy indicated agglomerates size in β-SiC synthesis is less than 100 nm. Finally, TEM studies revealed morphology of β-SiC particles treated in 1500˚C and after 1hr aging is spherical with (20-30) nm siz

Microstructural evolution of a commercial ultrafine alumina powder densified by different methods

The densification and grain growth of bodies made from a commercial ultrafine alumina powder was investigated. The primary powder was initially subjected to dry (uniaxial cold pressing) and wet shaping (slip casting), followed by conventional (CS)-, two step (TSS)-, and microwave (MS) sintering to explore the effect of each series of treatments on the densification and microstructural evolution of the specimens. It was demonstrated that a uniform microstructure with higher density would be obtained using the wet shaping method. In addition, microwave sintering was found to be more effective into the densification of the specimens and in yielding a finer grain structure. It is believed that the high heating rate and effective particle packing are responsible for the improvements in these properties. On this basis, it was also demonstrated that the fracture toughness of the samples increased significantly through the application of microwave sintering. (C) 2010 Elsevier Ltd. All rights reserved

Investigation of Photocatalytic Properties of NiO/TiO2 Layers Grown via PEO/EPD Method

Titanium dioxide-nickel oxide porous coatings were synthesized by Plasma Electrolytic Oxidation (PEO)/ ElectroPhoretic Deposition (EPD) in one step and within a short time. The main purpose of this research was to increase photocatalytic activity of titanium oxide by increasing surface area and coupling of titanium oxide with nickel oxide. Applied voltage effects on phase structure, surface morphology and photocatalytic efficiency of coatings were studied. Phase structure and surface morphology of the synthesized catalysts were investigated by XRD and SEM, respectively. Photocatalytic efficiency of the samples was studied through measuring the decomposition rate of 4-chlorophenol. The results showed that the coatings mainly consisted of anatase and nickel oxide phases whose amounts in coatings increased with the voltage. There was an enhancement of the photocatalytic efficiency in TiO2/NiO composite coatings compared with TiO2 coatings. Besides, there was an optimum amount of NiO to reach maximum photocatalytic efficiently

EFFECT OF ZrO2 PARTICLE SIZE ON MORPHOLOGY and SYNTHESIS OF NANO CaZrO3Via MOLTEN SALT METHOD

Well crystallized pure calcium zirconate (CaZrO3 ) nanopowder was successfully synthesized using the molten-salt method. CaCl2 , Na 2CO3, micro-ZrO 2and nano-ZrO 2 were used as starting materials. On heating, Na2CO3 reacted with CaCl 2to form NaCl and CaCO 3. Nano CaZrO 3 was formed by reacting equimolar amounts of in situformed CaCO 3 (or CaO) and ZrO 2 in molten Na 2CO3-NaCl eutectic mixture. CaZrO 3 particle size and synthesis temparture was tailored as a function of ZrO 2particle size. Due to the usage of nano-ZrO 2 , the molten salt synthesis (MSS) temperature was decreased and possible impurity phases in the final product were suppressed. The synthesis temperature was lowered to 800°C and soaking time of the optimal synthesis condition was reduced to 3h. After washing with hot-distilled water, the n-ZrO2sample heated at 800°C for 3h, was single phase CaZrO 3with 70-90 nm in particle size, while the m-ZrO 2sample heated at 1000°C for 3h, was single phase CaZrO 3 with 250-400 nm in particle size. Based on the TEM observation and thermodynamic analysis, the synthesized CaZrO 3 grains retained the morphology of the ZrO2 nanopowders, which indicated that a template formation mechanism play a dominant role in synthesis proces

High/room temperature mechanical properties of 3Y-TZP/CNTs composites

Spark Plasma Sintering (SPS) method was practiced, in the current investigation, to obtain fully dense materials with an excellent dispersion of MWCNTs (Multi-walled Carbon Nanotubes) within the matrix. Scanning and transmission electron microscopy micrographs as well as Raman Spectroscopy revealed no conspicuous signs of damages on the nanotubes' structure, as a result of applying appropriate processing measures. Measurements of mechanical properties' revealed the value of 15.2 +/- 0.4 MPa m(1/2) for indentation fracture toughness, impling our success to align transformation toughening (while the zirconia has the grain size around 1 mu m) with the effects of MWCNTs addition (5 wt%). High temperature mechanical properties of the composites have been investigated using Mechanical Spectroscopy (MS) up to 1600 K at frequency equal to 1 Hz. The MS results proved that CNTs could hinder grain-boundary sliding and subsequently lead to an enhanced creep resitance at high temperatures. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Sintering behavior of an ultrafine alumina powder shaped by pressure filtration and dry pressing

Master sintering curve (MSC) was used as a practical approach to analyse the sintering behavior of an ultrafine alumina powder. Non-isothermal sintering was carried out at three heating rates. The concept of the MSC has been used to investigate the effect of different shaping methods, i.e. dry pressing (DP) and pressure filtration (PF) on the apparent activation energy for sintering. Although no change in the dominant densification mechanism is expected, the interplay between different diffusion mechanisms taking place during the heating ramp may be affected by the shaping method. Values of 605 +/- 15 and 700 +/- 20 kJ/mol were determined for PF and DP samples, respectively. The lower activation energy for PF samples may be explained by the higher green density and homogeneity, smaller pore size in comparison with the DP samples. Furthermore, the mechanical properties (hardness and fracture toughness) of the samples are presented. (C) 2010 Elsevier B.V. All rights reserved