Implicit Milstein method for stochastic differential equations via the Wong-Zakai approximation

The aim of this paper is to derive a numerical scheme for solving stochastic differential equations (SDEs) via Wong-Zakai approximation. One of the most important methods for solving SDEs is Milstein method, but this method is not so popular because the cost of simulating the double stochastic integrals is high. For overcoming this complexity, we present an implicit Milstein scheme based on Wong-Zakai approximation by approximating the Brownian motion with its truncated Haar expansion. The main advantages of this method lie in the fact that it preserves the convergence order and also stability region of the Milstein method while its simulation is much easier than Milstein scheme. We show the convergence rate of the method by some numerical examples.     

ILSnCl2-mGO nanocomposite for efficient preconcentration of Red 2G via ultrasonic-assisted dispersive magnetic solid-phase extraction method: isotherm adsorption

Research on Chemical Intermediates - This article aims at Red 2G (R2G) preconcentration via dispersive magnetic solid-phase extraction, prior to its determination by a UV–visible...     

Applying Fe3O4-MoS2-chitosan nanocomposite to preconcentrate heavy metals from dairy products prior quantifying by FAAS

Research on Chemical Intermediates - A magnetic solid phase extraction method is presented to preconcentrate Pb(II), Cd(II), Ni(II) and Zn(II) simultaneously. The adsorbent (mMoS2-CS), consisting...     

Imposing nodes for linear structures during harmonic excitations using SMURF method

Vibration absorbers are usually designed using the finite element (FE) model of structures. It is generally believed that the modal models are more accurate than FE models, because in modal testing the model is built by direct measurement of the test structure. In this paper, a method is proposed to design a translational vibration absorber using the measured frequency response functions of a primary structure. The designed vibration absorber imposes a node on the structure when it is excited by a harmonic force. The method is based on the structural modification using experimental frequency response functions technique and determines the required receptance of the absorber at the excitation frequency. Moreover, a procedure is developed to suppress the vibration amplitude of two arbitrary points on a linear structure subjected to harmonic excitations by attaching two sprung mass absorbers. A cantilever beam is considered for the numerical case study, and the sprung masses are designed to suppress the vibration amplitude of the beam at the selected arbitrary points. A U-shape plate was considered for the experimental validation of the method for imposing a node using one absorber. Also, a beam was tested to demonstrate the effectiveness of method for imposing two nodes on the structures. The experimental results show that the designed absorbers can considerably suppress the vibration amplitude at the selected points on the structure.     

Morphological changes towards enhancing piezoelectric properties of PVDF electrical generators using cellulose nanocrystals

For the first time, a nanocomposite of poly(vinylidene fluoride)/cellulose nanocrystal (PVDF/CNC) is developed as a piezoelectric energy harvester. This is implemented through electrospinning of PVDF solutions containing different levels of CNC loading, i.e., 0, 1, 3 and 5 % with respect to PVDF weight. Analytical techniques including DSC, FTIR and WAXD are conducted to monitor the polymorphism evolution within electrospun nanocomposites as the CNC content is varied. The results imply that CNCs at the optimum concentration (3 and 5 %) can effectively nucleate β crystalline phases. The nucleation of α crystalline phases is also prevented when CNCs are present within the structure of PVDF electrospun fibers. These changes in polymorphism give PVDF/CNC nanocomposites enhanced piezoelectric characteristics compared to pure PVDF nanofibers. We have demonstrated that the developed nanocomposites can charge a 33-μF capacitor over 6 V and light up a commercial LED for more than 30 s. It is envisaged that the PVDF/CNC nanocomposites provide the opportunity for the development of efficient electrical generators as self-powering devices to charge portable electronics.     

13C-sialic acid labeling of glycans on glycoproteins using ST6Gal-I

Glycans that are either N-linked to asparagine or O-linked to serine or threonine are the hallmark of glycoproteins, a class of protein that dominates the mammalian proteome. These glycans perform important functions in cells and in some cases are required for protein activity. Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for studying glycan structure and interactions, particularly in a form that exploits heteronuclei such as 13C. Here an approach is presented that that uses alpha-2,6-sialyltransferase (ST6Gal-I) to enzymatically add 13C-N-acetylneuraminic acid (NeuAc or sialic acid) to glycoproteins after their preparation using nonbacterial hosts. ST6Gal-I is itself a glycoprotein, and in this initial application, labeling of its own glycans and observation of these glycans by NMR are illustrated. The catalytic domain from rat ST6Gal-I was expressed in mammalian HEK293 cells. The glycans from the two glycosylation sites were analyzed with mass spectrometry and found to contain sialylated biantennary structures. The isotopic labeling approach involved removal of the native NeuAc residues from ST6Gal-I with neuraminidase, separation of the neuramindase with a lectin affinity column, and addition of synthesized 13C-CMP-NeuAc to the desialylated ST6Gal-I. Chemical shift dispersion due to the various 13C-NeuAc adducts on ST6Gal-I was observed in a 3D experiment correlating 1H-13C3-13C2 atoms of the sugar ring.     

TLC Quantification of Methylparaben on an Inorganic Ion-Exchanger in the Presence of Other Food Additives

JPC – Journal of Planar Chromatography – Modern TLC - Rapid separation of methyl p-hydroxybenzoate from ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, p-hydroxybenzoic acid, benzoic...     

Antioxidant, nitric oxide scavenging and malondialdehyde scavenging activities of essential oils from different chemotypes of Zataria multiflora

The antioxidant, nitric oxide (NO) scavenging and malondialdehyde (MDA) scavenging activities of different Zataria multiflora (ZM) chemotype essential oils (EOs) were investigated. The main components are: ZM1 (carvacrol, p-cymene), ZM2 (carvacrol, p-cymene), ZM3 (carvacrol, p-cymene), ZM4 (linalool), ZM5 (carvacrol, p-cymene, thymol), ZM6 (thymol, carvacrol, p-cymene, γ-terpienene), ZM7 (thymol, p-cymene, γ-terpienene) and ZM8 (carvacrol, linalool, p-cymene, thymol). The antioxidant capacities were estimated to be 863?±?55, 619?±?27, 876?±?32, 38?±?9, 649?±?50, 595?±?40, 696?±?41 and 618?±?9?μg ascorbic acid equivalents per millilitre for ZM1 to ZM8, respectively. The NO scavenging values were estimated to be 54?±?1.2, 50?±?1.4, 63?±?1, 0.60?±?0.1, 53?±?0.7, 53?±?1.5, 38?±?1.1 and 46.5?±?3?μg ascorbic acid equivalents per millilitre for ZM1 to ZM8, respectively. The MDA scavenging values were estimated to be 19?±?1, 9?±?1, 24?±?1, 1.6?±?0.6, 12?±?1, 11.7?±?1, 10?±?1 and 12.5?±?1.3?μg ascorbic acid equivalents per millilitre for ZM1 to ZM8, respectively. Among these EOs, ZM3 with carvacrol and p-cymene had higher antioxidant, NO scavenging and MDA scavenging properties.     

Frequency domain aperture for the gain bandwidth reduction of stimulated Brillouin scattering

In this Letter, we propose a novel method based on the inhomogeneous Brillouin gain saturation to reduce the gain bandwidth significantly below its natural value. Based on our first experiments, we report a decrease of the bandwidth in a standard single mode fiber down to 3 MHz.