Synthesis of thermally stable metal substituted hydroxy apatites for the selective oxidation of light paraffins

Hydroxyapatite and a series of hydroxyapatite-type compounds containing Co, Fe or Sr were synthesized by co-precipitation and characterized by ICP-OES, BET, IR, Raman spectroscopy, powder and in-situ XRD, SEM, TEM, TPR, TPD and TGA. In-situ XRD and TGA studies indicate that the materials are able to maintain their structure at temperatures reaching 900 °C. The TPD data indicated that acidic sites of varying strengths were present in all the three hydroxyapatites. From SEM, the surface of the materials consisted of an agglomeration of irregular plate-like particles. The catalytic activity of the compounds was investigated in the oxidation of n-pentane and n-hexane. The conversion of the feed and composition of the products were largely influenced by changes in the temperature and flow rates. For n-pentane, the products consisted of lower hydrocarbons and oxygenated compounds, carbon oxides and very small amounts 1,3-pentadiene, furan and furfural. Low conversions of n-hexane were obtained for all the tested catalysts and selective products were the hexene isomers and some aromatics. KEY WORDS: Hydroxyapatite, Selective oxidation of n-pentane and n-hexane, Characterization, Oxygenates, Olefins Bull. Chem. Soc. Ethiop. 2013, 27(1), 57-68.DOI: http://dx.doi.org/10.4314/bcse.v27i1.

Kinetics and Mechanism of the Oxidation of Coomassie Brilliant Blue-R Dye by Hypochlorite and Role of Acid Therein

The kinetics of the oxidation of a triphenylmethane dye, Brilliant Blue-R (BB–Na+), in aqueous solution by hypochlorite as a function of pH was investigated. While the degradation of dye obeyed pseudo-first-order kinetics, the oxidation of the dye occurred through two competitive reactions facilitated by [OCl–] and [HOCl]. Both reactions exhibited first-order dependence on [OCl–] and [HOCl], respectively, but the hypochlorous acid initiated reaction was about ten times faster. The relative importance of the two paths rested on the pH-dependent concentrations of hypochlorite and hypochlorous acid. The overall second-order rate constants for the OCl– and HOCl initiated reactions are 1.2±0.2M–1 s–1 and 22.2±1.2M–1 s–1, respectively. The reaction energy parameters were determined as Ea=35.5 kJ mol–1,ΔHt=33.1 kJ mol–1 and ΔSt=–191.9 JK–1 mol–1 for the OCl– driven oxidation; and Ea= 26.8 kJ mol–1, ΔHt=29.3 kJ mol–1 and ΔSt=–204.6 JK–1 mol–1 for the HOCl facilitated reaction. The governing rate law and probable reaction mechanism were elucidated and validated by simulation. The three main oxidation products were 4-(4-ethoxyphenylamino)benzoic acid, 3-[(ethyl-hydroxyamino)methyl]benzene sulfonic acid and 6’-chloro-5’-hydroxybicyclohexylidene-2,5,2’-triene-4,4’-dione.KEYWORDS Brilliant Blue-R, oxidative degradation, hypochlorite, hypochlorous acid, kinetics, simulations.PDF and Supp files attache

Passive microfluidic interconnects

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaf 44).Equipment and procedures were developed to test two passive microfluidic interconnect rings held together by the friction forces on the contact surfaces. The second design forms fluid seals by means of thin flared rings of compliant material being compressed into undersized sockets. Interconnects were tested in pairs and arrays. The sealing performance of the first design was found to be highly dependent on the material and surface finish of the features, and the design was found to be largely intolerant to the misalignment inherent in arrays. The second design successfully seals up to 150 psi and is capable of compensating for misalignment to seal in arrays of six interconnects.by Aparna S. Jonnalagadda.S.B

Magnetic induction systems to harvest energy from mechanical vibrations

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references.This thesis documents the design process for magnetic induction systems to harvest energy from mechanical vibrations. Two styles of magnetic induction systems - magnet-through-coil and magnet-across-coils - were analyzed. MATLAB models were created to serve as a design aid and optimization tool for both styles of magnetic induction systems. Prototypes were built to test the predictions of the MATLAB models. The experimental data was found to be in good agreement with the model predictions.by Aparna S. Jonnalagadda.S.M

Towards understanding lamin gene regulation

The lamins are components of the nuclear lamina, which forms a fibrous meshwork lining the inner nuclear membrane. Lamina-membrane interactions play a crucial role during nuclear disassembly and reassembly at mitosis, whereas lamina-chromatin association has been proposed to be essential for chromatin organization. The composition of the lamina changes considerably during embryonic development and cell differentiation. Recent studies have provided insights into the regulation of the lamin genes

The effect of synthesis method on the structure, and magnetic and photocatalytic properties of hematite (α-Fe2O3) nanoparticles

Samples of hematite (α-Fe2O3) nanoparticles have been synthesized through the co-precipitation route in cetyltrimethylammoniumbromide (Hem_PR), via a citric acid sol-gel method (Hem_SG) and a modified sol-gel method inTween20 (Hem_TW), and each were annealed at three different temperatures (400, 500 and 600 °C). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission and high-resolution electron microscopy (TEM and HRTEM), Mössbauer spectroscopy and by means of a vibrating sample magnetometer (VSM). In addition, the photocatalytic behaviour of each sample was tested on the degradation of rhodamine B (RhB) in solution. All the characterization techniques showed the formation of phases of pure hematite nanoparticles with improved crystallinity after higher temperature annealing. However, the nanoparticles synthesized in Tween 20 showed the smallest particle size and highest BET surface area, saturation magnetization and photocatalytic activity. Of particular note was the ability of Tween 20 to control the growth of the particles so that grain sizes well below 10 nm were obtained. Thus, Tween 20, when used as a surfactant in the sol-gel route, can serve to improve the physical properties of synthesized hematite nanoparticles.Keywords: Hematite, nanoparticles, Mössbauer spectroscopy, magnetic properties, Tween 20, photocatalysi

Positive solutions of nabla fractional boundary value problem

In this article, we consider the following two-point discrete fractional boundary value problem with constant coefficient associated with Dirichlet boundary conditions. \begin{equation*} \begin{cases} -\big{(}\nabla^{\nu}_{\rho(a)}u\big{)}(t) + \lambda u(t) = f(t, u(t)), \quad t \in \mathbb{N}^{b}_{a + 2}, \\ u(a) = u(b) = 0, \end{cases} \end{equation*} \noindent where $1 < \nu < 2$, $a,b \in \mathbb{R}$ with $b-a\in\mathbb{N}_{3}$, \mathbb{N}^b_{a+2} = \{a+2,a+3,\hdots,b\}, $|\lambda| < 1$, $\nabla^{\nu}_{\rho(a)}u$ denotes the $\nu^{\text{th}}$-order Riemann--Liouville nabla difference of $u$ based at $\rho(a)=a-1$, and $f : \mathbb{N}^{b}_{a + 2} \times \mathbb{R} \rightarrow \mathbb{R}^{+}$. \noindent We make use of Guo--Krasnosels'ki\v{\i} and Leggett--Williams fixed-point theorems on suitable cones and under appropriate conditions on the non-linear part of the difference equation. We establish sufficient requirements for at least one, at least two, and at least three positive solutions of the considered boundary value problem. We also provide an example to demonstrate the applicability of established results

Potent and Innovative Management Of RDF Statistics In Cloud

We portray DiploCloud, a proficient and versatile appropriated RDF information administration framework for the cloud. As opposed to past methodologies, DiploCloud runs a physiological examination of both case and pattern data before parceling the information. In this, we depict the engineering of DiploCloud, its primary information structures, and also the new algorithms we use to segment and appropriate information. We likewise introduce a broad assessment of DiploCloud demonstrating that our framework is frequently two requests of greatness quicker than best in class frameworks on standard workloads

Effects of Ionic Liquids on Metalloproteins.

In the past decade, innovative protein therapies and bio-similar industries have grown rapidly. Additionally, ionic liquids (ILs) have been an area of great interest and rapid development in industrial processes over a similar timeline. Therefore, there is a pressing need to understand the structure and function of proteins in novel environments with ILs. Understanding the short-term and long-term stability of protein molecules in IL formulations will be key to using ILs for protein technologies. Similarly, ILs have been investigated as part of therapeutic delivery systems and implicated in numerous studies in which ILs impact the activity and/or stability of protein molecules. Notably, many of the proteins used in industrial applications are involved in redox chemistry, and thus often contain metal ions or metal-associated cofactors. In this review article, we focus on the current understanding of protein structure-function relationship in the presence of ILs, specifically focusing on the effect of ILs on metal containing proteins