Synthesis of new chrysin derivatives with substantial antibiofilm activity

Molecular Diversity - Multidrug resistance mechanism of microorganisms towards conventional antimicrobials nowadays faces a common health problem. So, searching and development of new...     

Determination of elastic modulus of a beam by using electronic speckle pattern interferometry

This paper proposes a sonic resonance test for an elastic modulus measurement which is based on the electronic speckle pattern interferometry. Previous measurement technique of elastic constant has the limitation of application for thin film or polymer material because contact to specimen affects the result. It has been developed as a non-contact optical measurement technique which can visualize resonance vibration mode shapes with whole field. The maximum vibration amplitude at each vibration mode shape is a clue to find the resonance frequencies. The dynamic elastic constant of test material can be easily determined from vibration of a beam equation using the measured resonance frequencies. The proposed technique is able to give high accurate elastic modulus of materials through a simple experimental set-up and analysis. The experimental result also compared to the theoretical result.     

Reconstruction of digital hologram of small particles on arbitrarily tilted plane using digital holography

Digital holographic off-axis geometry is presented for the reconstruction of the digital hologram of small particles in an arbitrarily tilted plane. A single hologram is sufficient to obtain a well focused clear image. We can't obtain clear images of small particles in the case of plane tilted to the detector plane by ordinary reconstruction method because of the rotation of the hologram plane. Rotational transformation based on coordinate rotation in Fourier space makes it possible to reconstruct holographic images on any plane in the object space. The reconstruction of digital hologram is based on the plane wave expansion of the diffracted wave fields, using Fourier optics and the two-axis rotation of the wave vectors. With this method, the object-to-hologram distance can be any small distance because the minimum distance requirement does not apply.     

Assessment of annual effective dose from natural radioactivity intake through wheat grain produced in Faisalabad,Pakistan

Wheat is staple food of the people of Pakistan. Phosphate fertilizers, used to increase the yield of wheat, enhance the natural radioactivity in the agricultural fields from where radionuclides are transferred to wheat grain. A study was, therefore, carried out to investigate the uptake of radioactivity by wheat grain and to determine radiation doses received by human beings from the intake of foodstuffs made of wheat grain. Wheat was grown in a highly fertilized agricultural research farm at the Nuclear Institute of Agriculture and Biology (NIAB), Faisalabad, Pakistan. The activity concentration of ⁴⁰K, ²²⁶Ra and ²³²Th was measured in soil, single superphosphate (SSP) fertilizer, and wheat grain using an HPGe-based gamma-ray spectrometer. Soil to wheat grain transfer factors determined for ⁴⁰K, ²²⁶Ra and ²³²Th were 0.118 ± 0.021, 0.022 ± 0.004 and 0.036 ± 0.007, respectively, and the annual effective dose received by an adult person from the intake of wheat products was estimated to be 217 μSv.     

Stability‐indicating ultra‐performance liquid chromatography method for the estimation of thymoquinone and its application in biopharmaceutical studies

Thymoquinone (THQ) is known for its neuroprotective and anti‐convulsant properties in preclinical studies. We herewith describe a simple, rapid, selective, sensitive and stability‐indicating UPLC method for the estimation of THQ and its application to biopharmaceutical studies such as in vitro release from nanoparticulate system and in vivo pharmacokinetic study. The method employed gradient elution using a Waters Acquity HSS‐T3 C₁₈ (100 × 2.1 mm, 1.8 µm) UPLC column. The mobile phase consisted of water and acetonitrile, pumped at a flow rate of 0.5 mL/min. The injection volume was 5 µL and THQ was monitored at 294 nm wavelength with a total run time of 6 min. In solution as well as in plasma, the method was found to be linear (r ≥ 0.998), precise (CV ≤ 2.45%) and accurate (recovery ≥ 84.8%) in the selected concentration range of 0.1–0.8 µg/mL. Forced degradation studies revealed that THQ undergoes degradation under acidic, basic, oxidation and UV light stress conditions. However, the developed UPLC method could effectively resolve degradation product peaks from THQ. Further, no interference was found at the retention time of THQ from any plasma components, indicating selectivity of the developed method. For solutions, the limits of detection and quantitation of the method were found to be 0.001 and 0.0033 µg/mL, respectively; while in plasma they were 0.006 and 0.02 µg/mL, respectively. The validated method was successfully applied to quantify THQ in dissolution medium as well as oral in vivo pharmacokinetic study of THQ suspension and THQ‐ solid lipid nanoparticle (THQ‐SLN) formulation. A 2‐fold increase in the relative bioavailability was observed with the THQ‐SLN compared with THQ. The results indicate that the SLN significantly increased plasma concentrations and retention within the systemic circulation. Copyright © 2010 John Wiley & Sons, Ltd.     

Interplay between two spin states determines the hydroxylation catalyzed by P450 monooxygenase from Trichoderma brevicompactum

Tri11 (now renamed as tri22) encoded cytochrome P₄₅₀ monooxygenase in Trichoderma brevicompactum catalyzes the C-4 C-H hydroxylation of 12, 13-epoxytrichothec-9-ene (EPT) to produce trichodermol in the biosynthetic pathway of trichodermin/harzianum A. The density functional theory (DFT)-quantum mechanics (QM) approach is applied to elucidate the hydroxylation of EPT by using a model active species of P₄₅₀ (Cpd I). The QM calculations were performed on the active site complex, to find out transition-state structure, intermediate, and product complexes for the two spin states at different potential energy surfaces. The two state reactivity rebound-free product formation resulted from the interplay of two spin states (doublet and quartet).     

Multielement analysis of water residue: A PIXE measurement

Summary A multielement PIXE method has been developed to analyse water residue obtained by evaporation technique. In this analysis, 250 ml of water sample mixed with 200 mg of cellulose powder is evaporated on steam bath in a platinum dish. From the residue thus obtained standard pellets are made for proton irradiation to excite characteristic X-rays. Proton irradiations were performed with 2.5 MeV beams with 20 nA intensity and the characteristic X-rays were detected with a high resolution Si(Li) detector and processed by standard electronics. A synthetic standard of cellulose matrix for concentration calibration was prepared by adding different elements from atomic absorption standards and homogeneously mixing them with the matrix with methanol.Using the present methodology, for a 20 C irradiation, it is possible to analyse quantitatively 10–15 different elements (K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Sr, Pb, etc.) in water samples. The procedure thus developed has been applied to study the concentration profiles of heavy elements in the municipal water supplies in the city of Dhaka and the results are compared with recommended levels of heavy elements in drinking water. Various aspects of the method and the implications of the data reported here have been discussed.

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Multielement-Analyse von Wasserrückständen: PIXE-Messung

Zusammenfassung 250 ml des Wassers wurden mit 200 mg Cellulosepulver gemischt und eingedampft. Aus dem Rückstand wurden Tabletten für die Protonenbestrahlung gepreßt. Die Bestrahlung wurde mit 2,5 MeV und 20 nA durchgeführt; die charakteristischen Röntgenstrahlen wurden mit Hilfe eines hochauflösenden Si(Li)-Detektors gemessen und elektronisch aufgearbeitet. Synthetische Standards für die Cellulosematrix wurden aus AAS-Standards hergestellt (Mischung mit Methanol). Mit dem beschriebenen Verfahren konnten bei 20-C-Bestrahlung 10–15 verschiedene Elemente (K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Sr, Pb, u.a.) in Wasserproben bestimmt werden. Die Methode wurde zur Untersuchung der Konzentrationsprofile von Schwermetallen im Leitungswasser der Stadt Dhaka eingesetzt, die mit den für Trinkwasser empfohlenen Konzentrationen verglichen wurden. Verschiedene Gesichtspunkte des Verfahrens und der erhaltenen Resultate werden diskutiert.

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This research was supported in part by the International Atomic Energy Agency, Vienna, Austria     

Ultrasonic Study of Basic α‐Amino Acids in Different Acetate Salt Solutions at Different Temperatures

The ultrasonic velocity (U), has been measured for three α‐amino acids, namely L‐lysine monohydrochloride, L‐arginine and L‐histidine in solutions (1 mol/L aqueous) of sodium acetate (SA), potassium acetate (PA) and calcium acetate (CA) at different temperatures (303.15, 308.15, 313.15, 318.15 and 323.15 K). With the help of these results various ultrasonic derived parameters, viz. isentropic compressibility (κ_s), change in isentropic compressibility (Δκ_s), relative change in isentropic compressibility (Δκ_r), specific acoustic impedance (Z), relative association (RA), and apparent molal compressibility (?) have been estimated. The results have been interpreted in the light of intermolecular interactions between solute and solvent.