Aero-thermal analysis of a laminar separation bubble subjected to varying free-stream turbulence: Large Eddy Simulation

A quantitative analysis illustrating salient features of a Laminar Separation Bubble (LSB), its transition forming coherent structures, and associated heat transfer has been performed on a flat plate for varying free stream turbulence (fst) between 1.2% to 10.3%. A well-resolved Large Eddy Simulation (LES) developed in-house is used for the purpose. Flow separation has been induced by imposing an adverse pressure gradient on the upper boundary of a Cartesian domain. Isotropic perturbations are introduced at the inlet to mimic grid turbulence. With an increase of fst, an upstream shift in the mean reattachment point has been observed while the onset of separation remains almost invariant, shrinking the bubble length significantly. The transition of the shear layer is triggered by the Kelvin-Helmholtz (K-H) instability for fst of less than 3.3%, while Klebanoff modes (Kmodes) dictate the flow transition at fst greater than 6.5%. Further, a mixed mode, i.e., both K-H and K-modes, contribute to the flow transition at a moderate level of fst, lying between 3.3% and 6.5%. Thus, the roll-up of the shear layer appears in the second half of the bubble shedding large-scale vortices that keep their identity far downstream at low fst levels. On the contrary, the streamwise streaks via K-modes prior to the separation are found to interact with the LSB, resulting in an earlier breakdown of the shear layer with abundant small-scale vortices downstream at the moderate to high fst levels. However, higher surface-normal heat flux is associated with large-scale energetic coherent vortices

Spectrophotometric studies on chelating behavior of oxalohydroxamic acid with uranium in aqueous streams

Study of the complex formation of oxalohydroxamic acid (OHA) with uranium is investigated by spectrophotometry. Oxalohydroxamic acid forms orange-yellow complex with uranium(VI) in aqueous medium and shows maximum absorbance at 381 nm at pH 6.2. The stoichiometry of the coloured species is determined to be 1:5 ratios (uranium-oxalohydroxamic acid). A calibration graph is made for the concentration range of uranium from 10-100 mg/L. The molar absorption coefficient at 381nm, detection limit and Sendell’s sensitivity are 2230 LMol-1cm-1, 11 mg/L and 0.11 µg/cm2 respectively. Relative standard deviation is less than 2% and correlation coefficient is 0.998. In these studies, oxalohydroxamic acid complex with uranium, effect of reagent-metal ratio, pH and reagent stabilities are investigated. The results obtained by the proposed procedure are in good agreement with those obtained by the standard procedure. The advantage of the present study is that, it does not generate analytical waste because hydroxamic acids are composed of only C, H, N and O atoms they can be decomposed to gases so that their application in industrial processes will not lead to increase in waste volume. The method is also applicable for the determination of concentration of uranium in reprocessing samples. Keywords: Uranium, Oxalohydroxamic acid, Spectrophotometry, pH, Molar absorptivit

Controlled Synthesis of Nanomaterials using Reverse Micelles

Monophasic nanosized oxides were synthesised mainly from metal oxalate nanorods obtainedusing the reverse micellar method. This paper focuses on the methodology to obtain importantmetal oxides like tin dioxide, cerium oxide (CeO2 ), zirconia, and zinc oxide. The effect of oxidationstate of the metal ion on the morphology of the oxalates was studied. Nanorods of zinc (II)oxalate (120 nm in dia and 600 nm in length) were obtained while spherical particles of size 4Œ6 nm were obtained for cerium (III) oxalate. The decomposition of these precursors at highertemperature led to the formation of their respective oxides. Mixture of nanorods and nanoparticles of CeO2 was obtained while 3Œ4 nm sized ZrO2 nanoparticles were obtained by thermaldecomposition of zirconium oxalate precursor. The dielectric constant and loss were highly stablewith frequency (at room temperature) for both ceria and zirconia nanoparticles.  ZnO nanoparticles(55 nm sized) were obtained by the decomposition of zinc oxalate nanorods. Three peaks corresponding to free excitonic emission, free-to-bound, and donor-acceptor transitions were observed in the photolumine scence studies at 20 K for ZnO nanoparticles.Defence Science Journal, 2008, 58(4), pp.531-544, DOI:http://dx.doi.org/10.14429/dsj.58.167

A COMPARATIVE PLACEBO, CONTROL CLINICAL EVALUATION OF PHALATRIKADI KWATH IN MADHUMEHA WITH SPECIAL REFERENCE TO DIABETES MELLITUS TYPE2

The study was aimed to have a conceptual review of the disease Madhumeha and its treatment in particular to the use of an herbal drug†Phalatrikadi Kwath†and to compare its efficacy with the control drug (metformin) and placebo through scientific parameters in a double blind clinical control trial. Madhumeha, also known as Diabetes Mellitus is one of the types of Vataja prameha, that has been considered as an incurable disease (Mahagada). Due to indulgence in etiological factors it results in the incomplete formation of Kapha and Meda which further proceeds downward through the channels of Mutravaha srotas and get localized at Basti mukha leading to the symptoms like Prabhoota mutrata (polyurea), Avila mutrata (tubidity of urine) etc. As the disease is Chirakari, it requires an effective treatment which can be continued for a long time without any ill effects. Among the many treatment measures mentioned, Phalatrikadi kwath has been selected in this study and the effect was evaluated. The clinical study includes 50 patients of either sex between 30-60 years of age with Madhumeha (Type2 Diabetes Mellitus) were recruited having range of blood sugar (fasting 126-180 mg/dl, postprandial sugar, 200-250 mg/dl) attending the OPD of G.A.M Puri, Odisha and were divided into three groups. Group I (30 patients) were treated with trial drug (Phalatrikadi kwatha), Group II (10 patients) were treated with control drug (Metformin) and Group III (10 patients) were treated with placebo. All the three groups were recommended with uniform classically described diet (Ahara) & regimen (Vihara). Patients were evaluated in an interval of 15 days for one month. FBS, PPBS with clinical sign & symptoms were assayed. After evaluating the total effects of the treatment, it was observed that Phalatrikadi kwath along with diet and regimen gave satisfactory relief in comparison to control drug (metformin)which is an established drug

Enhanced functionalization of Mn2O3@SiO2 core-shell nanostructures

Core-shell nanostructures of Mn2O3@SiO2, Mn2O3@amino-functionalized silica, Mn2O3@vinyl-functionalized silica, and Mn2O3@allyl-functionalized silica were synthesized using the hydrolysis of the respective organosilane precursor over Mn2O3 nanoparticles dispersed using colloidal solutions of Tergitol and cyclohexane. The synthetic methodology used is an improvement over the commonly used post-grafting or co-condensation method as it ensures a high density of functional groups over the core-shell nanostructures. The high density of functional groups can be useful in immobilization of biomolecules and drugs and thus can be used in targeted drug delivery. The high density of functional groups can be used for extraction of elements present in trace amounts. These functionalized core-shell nanostructures were characterized using TEM, IR, and zeta potential studies. The zeta potential study shows that the hydrolysis of organosilane to form the shell results in more number of functional groups on it as compared to the shell formed using post-grafting method. The amino-functionalized core-shell nanostructures were used for the immobilization of glucose and L-methionine and were characterized by zeta potential studies

Synthesis of nanocrystalline materials through reverse micelles: a versatile methodology for synthesis of complex metal oxides

We have been successful in obtaining monophasic nanosized oxides with varying chemical compositions using the reverse micellar method. Here we describe our methodology to obtain important metal oxides like ceria, zirconia and zinc oxide. The oxalate of cerium, zirconium and zinc were synthesized using the reverse micellar route. While nanorods of zinc oxalate with dimension, 120 nm in diameter and 600 nm in length, could be obtained, whereas spherical particles of size, 4-6 nm, were obtained for cerium oxalate. These precursors were heated to form their respective oxides. Mixture of nanorods and nanoparticles of cerium oxide was obtained. ZrO2 nanoparticles of 3-4 nm size were obtained by the thermal decomposition of zirconium oxalate precursor. ZnO nanoparticles (55 nm) were obtained by the decomposition of zinc oxalate nanorods. Photoluminescence (PL) studies at 20 K shows the presence of three peaks corresponding to free excitonic emission, free to bound and donor-acceptor transitions. We also synthesized nanoparticles corresponding to Ba1−x Pb x ZrO3 using the reverse micellar route. The dielectric constant and loss were stable with frequency and temperature for the solid solution

Women’s Infertility - A Ayurvedic thought

Infertility primarily refers to the biological inability of a person to contribute to conception. In women, it may also refer to the state when she is not able to carry a pregnancy to its full term. Female infertility is caused due to structural problems like blocked Fallopian tubes, defect in cervical canal, uterine fibroid or polyps. Hormonal imbalance leading .ovulation problems too can cause infertility. From Ayurvedic perspectives, Shukra Dhatu can get affected by various physical, mental causes and even by serious diseases. Poor quality Shukra Dhatu can cause infertility in males and females

Formation of calcium oxalate nanoparticles in leaves: significant role of water content and age of leaves

Calcium oxalate monohydrate (COM) was synthesized in the presence of leaves which act as a source of oxalate ions. Three different leaves, viz. Ficus religiosa (peepal in India), Heterophragma adenophyllum (Katsagon) and Spinacia oleracea Linn. (spinach) were used for the synthesis, which led to nanoparticles of COM of size 100–300 nm, 40–70 nm and 150–200 nm respectively. The particles are highly monodisperse, spherical and uniform in size as shown by TEM studies. The amount of COM formed varied significantly (35–80%) with the type of leaf used. The yield could be inversely correlated with the water content of the leaves; though water is essential for the formation of COM (dry leaves do not yield COM). Our studies show that the secretion of oxalate ions (to form COM) from the cells occurs even in leaves which have been removed from the living plants and the ability to secrete oxalate ions increases with the age of the leaf. The young leaves of F. religiosa do not show COM formation. In the presence of chelating agents (like citric acid) which can bind to Ca2+ ions, COM is absent, suggesting that the secretion of oxalate ions is prevented

Sutika Paricharya - Post Natal Care in Ayurveda

Ayurveda give importance for the care of mother at every phase of her life specially when it comes to antenatal care and postnatal care. A postnatal period beginning immediately after the separation of placenta and extending up to 6 weeks, otherwise called as puerperium or puerperal period. Postnatal care certainly co-related with Sutika Paricharya explained in Ayurvedic classics. Garbhini and Sutika Paricharya are well described by our Ancient Ayurvedic scholars in their respective Samhitas. They have described dietary regimen, living style, and other required management for whole pregnancy and up to 6 month after delivery. In this stage mother should be educated to take care of herself and the new born baby. This period is of happiness and contentment, on one hand and physical and mental fatigue due to delivery, on the other hand, she become weak or emaciated after loss of blood and body fluid during delivery. Garbhini is much prone to the disease due to aggravation of Doshas. This further may be aggravated during delivery and puerperium due to loss of blood and other important Dhatus of body. Therefore she needs special and proper care during pregnancy as well as during puerperium. The regimen that helps the woman to regain her lost vitality and helps her body to revert back to prepregnant state is called Sutika Paricharya, as during this period she restores her health and strength