Development and Applications Of Photoflash-Pvdf Technique in Thermal Diffusitivity Measurement at Low Temperatures

The photoflash technique is developed and used for measuring thermal diffusivity of various types of material, at temperature range from -77K to ambient temperature. It uses a cheap and simple camera flash and polyvinlidene difluoride (PVDF) film as signal generating source and detector, respectively. The theoretical signal was derived based on the square pulse approximation of the camera flash that replaced Dirac-6 function approximation employed in other studies. Comparative studies on these two different approximations have been performed on SiCIB4C composites. Although the camera flash temporal shape is closer to square pulse, Dirac-6 function approximation is still valid for the limited case of PVDF signal that is significantly longer than camera flash pulse duration. The square wave approximation model was further used in determining the thermal diffusivity of superconductors, semiconductors, magnetoresistances, carbon nanotubes, ceramics, composites, polymers and porous samples. The thermal diffusivity for SiC/B4C composites and Sic doped with A1 decreased with increasing temperature. This suggests that thermal diffusivity is basically influenced by phonon interaction within lattice that determines the phonon mean free path. In case of superconducting materials, thermal diffusivity measurements were carried for BSCCO, doped with Samarium (Sm) at Bi, Sr and Cu sites and sintered for 24,48 and 100hrs respectively. The results were explained in terms of electronphonon and phonon-lattice interactions in association with the sample grain size. The magneto-resistive of LCMO doped with Er at La site was also studied in this study. Thermal diffusivity measurements revealed that the transition from metallic to insulator and from insulator to semiconductor behavior in the materials, were closely matched to the results obtained from electrical resistivity measurement of other researchers. The thermal diffusivity of carbon nanotubes (CNTs) decreased when the temperature was increased from low to room temperature. Besides, there were also double slope phenomena in the way the thermal diffusivity changed with composition of CNT in the range of temperature covered in the measurement. In the case of polymers of Emeraldine Base (EB) and Emeraldine Salt (ES), the thermal diffusivity changed with temperature as in other insulating materials. Finally, the effect of porosity on thermal diffusivity was studied using Nickel Copper Zinc Ferrite samples. The thermal diffusivity decreased with increasing porosity of the sample. The results also showed that porosity has a greater effect on thermal conductivity of the material than its thermal capacity

Latent heat flux and air temperature anomalies along an active fault zone associated with recent Iran earthquakes

Pre-earthquake physical and chemical interactions in the earth’s ground may cause anomalies in latent heat flux, air and surface temperature. Earthquakes occur when the energy accumulated in rocks releases. Sometimes, the movements of the ground cause ruptures in the earth’s surface and sometimes the two sides of an existing fault shift towards each other. In a structurally complex and inhomogeneous collision region such as the Iranian Plateau, seismicity is not the result of activity of a single fault but is due to energy discharge in fault zones hundreds of kilometers wide. Changes in latent heat flux and temperature, on and above the earth’s surface can be detected with thermal infrared (TIR) sensors such as NOAA-AVHRR, Terra/Aqua-MODIS, etc. Spatio-temporal distributions of surface latent heat flux (SLHF) and air temperature before and after two recent earthquakes in Iran have been studied. Anomalous patterns of higher SLHF formed a few days before the earthquakes of 20 Dec 2010 (6M) and 27 Jan 2011(6.5M) occurred in Kerman province and disappeared after the main events. Data analyses revealed at least 2–4 °C rises in air temperature along the nearby fault zone, as well. These changes were also in accordance with the abnormal relative humidity over the region. Significant rises in SLHF and air temperature may lead us to understand the energy exchange mechanism during the earthquakes. These anomalies prior to impending earthquakes can be attributed to the thermodynamic, degassing and ionization processes which are believed to be activated by the accumulated stress in the ground, insensible movements of the tectonic blocks, and micro-fracturing in the rocks especially along area’s active faults. Continuous monitoring of these potential precursors helps in differentiating earthquake related variations from seasonal changes and atmospheric effects

Relationship between human chorionic gonadotrapin (HCG) level in second trimester pregnancy and preeclampsia.

Background and aim: Many researches have shown a relationship between levels of βHCG in pregnancy and preeclampsia which can be used as a method for early diagnosis. The aim of this study was to determine relationship between levels of HCG in second trimester of pregnancy and preeclampsia. Methods: This study was conducted as a Nested case control study. Blood samples were taken from 1200 pregnant women who were in their second trimester of pregnancy and were admitted for prenatal care in Arak prenatal clinics. After isolation of serums blood samples were stored in -20◦C until delivery time. Finally serum HCG levels blood pressure proteinurea edema seizure and neonate statue were analyzed in 50 preeclamptic women (case group) and were compared with 50 normotensive women (control group). Results: All women were complicated with mild preeclampsia. The mean of the βHCG in preeclamptic women was 43.08±32.56 Iu/ml and means of HCG in normotensive women was 27.48±25.97 mu/ml (

Investigation of lipid profiles and lipid peroxidation in patients with type 2 diabetes.

The aim of this study was to investigat the lipid peroxidation of plasma as a marker of oxidant-induced protein damage the effects of oxygen radicals on glycated-hemoglobin and to find out the relationship between the increase level of Malondialdehyde (MDA) on HbA1C, lipid profiles and FBS (Fasting Blood Sugar) in patients with type 2 diabetes. This randomized study included 200 individuals, 100 cases had history of diabetic for at least 3 years (file in Isfehan hospital, Diabetic Center of Medical Sciences University) and 100 cases as the control group without history of diabetes. In both groups, level of MDA, FBS, lipid profiles and HbA1C were determined in fasting blood samples. Results showed that MDA level in diabetic patients was significantly (p<0.005) higher (0.9222 ± 0.3 μmol/L) than those in the control group (0.7428 ± 0.04μmol/L). The same was also true (p<0.05) for the level of HbA1C (9.387 ± 2.4 mg/dl in diabetic patients and 7.356 ± 1.0 mg/dl in the control group) and the FBS (163.31 ± 56mg/dl in patient group and 85.740 ± 10.1 in the control group). Furthermore, the concentration of, LDL significantly was higher (p<0.05) and the HDL level were significantly lower (p<0.05) in case group as compared to control group. The increased plasma lipid peroxidation and decreased plasma HDL that we observed in patients with type 2 diabetes mellitus indicated that these may predispose to the development of cardiovascular complications

Thermal diffusivity measurement of BSCCO superconductor (85 to 300 K) using PVDF transducer

Thermal diffusivity measurement of the Bi-Pb-Sr-Ca-CII-O superconducting ceramic sample is reported. In this work camera flash and polyvinylidene difluoride (PVDF) film were respectively used as heating source and pyroelectric detector. The theoretical signal calculation based on Dirac- function approximation for camera flash temporal profile was used to deduce the thermal diffusivity. The measurement was done from 85 K to room temperature. The thermal diffusivity curve shows a dip at the resistive transition onset temperature and a cusp at the zero-resistance temperature. Thus, we found that the PVDF transducer is very effective in determining the normal-to-superconductor transition phenomena and also for the measurement of the thermal diffusivity of the superconducting samples at low temperatures

Semileptonic form factors D → \rightarrow π \pi , K and B → \rightarrow π \pi , K from a fine lattice

We extract the form factors relevant for semileptonic decays of D and B mesons from a relativistic computation on a fine lattice in the quenched approximation. The lattice spacing is a = 0.04 fm (corresponding to a -1 = 4.97 GeV), which allows us to run very close to the physical B meson mass, and to reduce the systematic errors associated with the extrapolation in terms of a heavy-quark expansion. For decays of D and Ds mesons, our results for the physical form factors at \ensuremath q^2 = 0 are as follows: \ensuremath f_+^{D\rightarrow\pi}(0) = 0.74(6)(4) , \ensuremath f_+^{D \rightarrow K}(0) = 0.78(5)(4) and \ensuremath f_+^{D_s \rightarrow K} (0) = 0.68(4)(3) . Similarly, for B and Bs we find \ensuremath f_+^{B\rightarrow\pi}(0) = 0.27(7)(5) , \ensuremath f_+^{B\rightarrow K} (0) = 0.32(6)(6) and \ensuremath f_+^{B_s\rightarrow K}(0) = 0.23(5)(4) . We compare our results with other quenched and unquenched lattice calculations, as well as with light-cone sum rule predictions, finding good agreemen

Effects of Sesamum indicum L. on fibrinogen and factor 7 in hypercholesterolemic rabbits

زمینه و هدف: فعالیت بیش از حد فاکتورهای هموستاتیک به عنوان عوامل خطر در بیماری های قلبی-عروقی شناخته شده اند. هدف از این مطالعه بررسی اثر کنجد و روغن کنجد بر میزان فیبرینوژن و فاکتور 7 در خرگوش های مصرف کننده کلسترول بالا بوده است. روش بررسی: در این مطالعه تجربی تعداد 32 سر خرگوش نر به طور تصادفی به چهار گروه آزمایشی هشت تایی تقسیم شدند. طی یک دوره 60 روزه، گروه اول غذای معمولی، گروه دوم غذای پر کلسترول (1)، گروه سوم غذای پر کلسترول به همراه کنجد (10) و گروه چهارم غذای پر کلسترول به همراه روغن کنجد (5) دریافت نمودند. میزان فاکتور هفت و فیبرینوژن سرم در زمان قبل از شروع آزمایش و بعد از پایان ماه دوم تعیین و در گروه های مختلف به کمک آزمون های آماری ANOVA و شفه با یکدیگر مقایسه شدند. یافته ها: در ابتدای دوره میانگین فاکتورهای بیوشیمیایی در بین گروههای مورد مطالعه تفاوت معنی داری نداشتند ولی میزان فیبرینوژن در گروه پرکلسترول نسبت به رژیم پایه افزایش معنی داری پیدا کرد (05/0

Thermal diffusivity measurement of zinc‐aluminum‐layered double hydroxide using photoflash technique

The photoflash technique has been widely used for measuring thermal diffusivity of various types of materials. In this report thermal diffusivity of Zn‐Al layered double hydroxide synthesized at different ratios of Zn to Al composition is presented. The samples were prepared using Zn(NO3)2 and Al(NO3)3 solutions at pH of 10 by drop wise addition of NaOH solution with vigorous stirring under nitrogen atmosphere. Different compositions of Zn to Al molar ratios were obtained by changing the molar ratio of Zn(NO3)2 to Al(NO3)3. The slurry formed was kept at 70 °C in an oil bath shaker for 18 h, filtered, washed and dried in an oven for 18 h at 70 °C. A simple photo flash and polyvinlidene diflouride (PVDF) film was used as light source and thermal wave detector, respectively. Thermal diffusivity of Zn‐Al layered double hydroxide measure at room temperature was found increase with different compositions for Zn‐Al ratio of 3–5

Immune Response to Synthesized Pnipam-Based Graft Hydrogels Containing Chitosan and Hyaluronic Acid

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Helvetica} Biomaterials are thought to be the magical solution to improving the quality of life and lengthening lifespans of human beings. To date, there is no biomaterial that can completely escape immune responses. However, successes have recently been made in reducing immune responses to biomaterials.P(N-isopropylacrylamide) (PNIPAM), chitosan , and hyaluronan are examples of polymers that are gaining great interest in the field of biomaterials. The most attractive property of PNIPAM is thermo-responsiveness. Adequate literature has been published on improving the mechanical strength of PNIPAM, but not much has been published on host response to PNIPAM based graftpolymers. Chitosan and hyaluronan are generally considered non-toxic and nonimmunogenic. The first part of this project focuses on the synthesis and characterization of hyaluronan-grafted-chitosan-grafted-P(NIPAM-co-acrylic acid), while the second part examines the effect of grafting on the extent of immune reaction compared to P(NIPAM-co-acrylic acid) alone. The incorporation of chitosan into P(NIPAM-co-acrylic acid), and hyaluronan into chitosan-grafted-P(NIPAM-coacrylic acid) was confirmed by Fourier Transform Infrared Spectroscopy, Nuclear Magnetic Resonance , 2,4,6-trinitrobenzenesulfonic acid (TNBS), and Lower Critical Solution Temperature (LCST) experiments. The optimum molecular p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Helvetica} weight for P(NIPAM-co-acrylic acid) that could provide sufficient amount of reactive sites while maintaining LCST below 37°C was found to be in the range of 2-2.5kDa. Western blotting results demonstrated that incorporating chitosan into P(NIPAM-co-acrylic acid) reduces the amount of fibrinogen, fibronectin, and vitronectin adsorbed, and eliminates complement component 3 (C3) adsorption. Furthermore, incorporating hyaluronan eliminates more inflammatory proteins including fibrinogen and reduces Immunoglobulin G (lgG) adsorption. Chitosan-grafted-P(NIPAM-co-acrylic acid) elicited lower levels of inflammatory cytokine release compared to P(NIPAM-co-acrylic acid), but higher than hyaluronan-grafted-chitsan-grafted-P(NIPAM-co-acrylic). In vitro and in vivo results revealed lowest density of leukocytes adhesion to hyaluronan containing surface compared to the other surfaces. The extent and duration of inflammation was reduced on chitosan-grafted-P(NIPAM-co-acrylic acid) and hyaluronangrafted-chitosan-grafted-P(NIPAM-co-acrylic acid) hydrogels.Master of Applied Science (MASc