Determination of 90Sr and 210Pb in deer bone samples by liquid scintillation counting after ion-exchange procedures

This work describes a procedure for the isolation of ⁹⁰Sr and ²¹⁰Pb from deer bones by anion exchange methods and their sequential measurement by LSC. To prevent collection of Pb on the Sr·Spec^® resin we first separated Pb on a Dowex anion exchange column. Sr, which is not held back on the Dowex column, was then purified using Sr·Spec^® resin: first Ca and the Ra isotopes were eluted with 3 M HNO₃ and then Sr was eluted with distilled water. With this 2-steps procedure pure ²¹⁰Pb and ⁹⁰Sr spectra can be achieved. The chemical yield of both steps was determined by ICP-MS. Our ⁹⁰Sr results show satisfying agreement with data obtained by a shorter Sr·Spec^® method and also by the “classical” ⁹⁰Sr determination using fuming nitric acid. Also ²¹⁰Pb results were checked by re-measuring bone samples with already known ²¹⁰Pb activities. Further our method was verified on the reference sample IAEA-A-12.     

TiO2-based photocatalysts impregnated with metallo-porphyrins employed for degradation of 4-nitrophenol in aqueous solutions: role of metal and macrocycle

Photodegradation of organic compounds in water solutions by means of economically advantageous and environment-friendly processes is a topic of growing interest. In recent years a great attention has been devoted to TiO₂-based photocatalysts for the oxidative degradation of various organic pollutants. In this context, we have prepared new photo-catalytic polycrystalline TiO₂ systems impregnated with sensitizers, i.e., copper, iron or manganese porphyrins, and investigated their photoactivity for 4-nitrophenol oxidation compared with that of bare TiO₂. A significant improvement of the photoreactivity was observed in the case of TiO₂ impregnated with copper porphyrin, while only a slight beneficial effect was observed in the case of iron porphyrin. In contrast, the presence of manganese porphyrin appeared to be detrimental.     

Elastin-calmodulin scaffold for protein microarray fabrication

In this work, we report a new method to reversibly immobilize proteins to a surface in a functionally active orientation directly from cell lysate by employing a fusion protein consisting of a thermal-responsive elastin (ELP) domain as the surface anchor and a calcium-responsive calmodulin (CalM) domain for protein capturing. Incorporation of an M13 tag into recombinant proteins enables not only easy surface immobilization but also direct purification from cell lysates. The feasibility of concept was demonstrated using the M13-tagged yellow fluorescent protein (M13-YFP). The ELP-CalM functionalized surfaces were shown to capture M13-YFP directly from cell lysate through the specific calmodulin-M13 association in a calcium-dependent manner. We also demonstrated that immobilization is reversible; the bound proteins were released from the surface in the presence of EDTA.     

Physical,Thermal and Biological Properties of Yellow Dyes with Two Azodiphenylether Groups of Anthracene

Two yellow bis-azo dyes containing anthracene and two azodiphenylether groups (BPA and BTA) were prepared, and an extensive investigation of their physical, thermal and biological properties was carried out. The chemical structure was confirmed by the FTIR spectra, while from the UV–Vis spectra, the quantum efficiency of the laser fluorescence at the 476.5 nm was determined to be 0.33 (BPA) and 0.50 (BTA). The possible transitions between the energy levels of the electrons of the chemical elements were established, identifying the energies and the electronic configurations of the levels of transition. Both crystals are anisotropic, the optical phenomenon of double refraction of polarized light (birefringence) taking place. Images of maximum illumination and extinction were recorded when the crystals of the bis-azo compounds rotated by 90° each, which confirms their birefringence. A morphologic study of the thin films deposited onto glass surfaces was performed, proving the good adhesion of both dyes. By thermal analysis and calorimetry, the melting temperatures were determined (~224–225 °C for both of them), as well as their decomposition pathways and thermal effects (enthalpy variations during undergoing processes); thus, good thermal stability was exhibited. The interaction of the two compounds with collagen in the suede was studied, as well as their antioxidant activity, advocating for good chemical stability and potential to be safely used as coloring agents in the food industry.     

Influence of Cyclodextrins on the Kinetics of Oxidation of Amino Acids and BSA by Hydrazyl Radicals

The kinetics of oxidation of amino acids (Arg, His, Lys, Phe, Thr and Tyr), a dipeptide (Gly-His), and BSA (bovine serum albumin) by two persistent water soluble free radicals of the hydrazyl type has been studied.The rate decreases in the order Arg>Lys>Tyr>Thr>HisBSAPheGly-His with bothfree radicals. Addition to the reaction mixture of - and -cyclodextrin decreases the oxidation rate, probably due to amino acidencapsulation in the cyclodextrin cavity. -Cyclodextrin protects more efficiently against oxidation than -cyclodextrin.     

Ethylethanolammonium 4-nitrobenzoate

Journal of Thermal Analysis and Calorimetry - In the present studies, the thermal behaviour of NaUO2BO3 has been investigated. This compound is a potential product of interaction between the...     

Development of horseradish peroxidase/layered double hydroxide hybrid catalysis for phenol degradation

Research on Chemical Intermediates - Both photocatalytic and enzymatic degradation of phenol were studied in order to evaluate and to compare the catalytic potential of both methods. For this,...     

Physical properties (thermal,thermomechanical, magnetic,and adhesive) of some smart orthodontic wires

Thermal, thermomechanical, and caloric properties of commercial orthodontic wires (produced by Natural Orthodontics Corp., USA) with cylindrical and rectangular geometry were studied. Depending on the applied forces, there were identified the range of elasticity, the elasticity–viscoelasticity coexistence domain and the domain in which a maximum force of 18 N is applied, for the orthodontic wires. When increasing the thickness of orthodontic wires, deformation decreases. The Controlled Force Module, in the tension mode, was used for the determination of the orthodontic wires elongation at application of the stretching forces from 0 to 13 N, at 35 °C, maintaining each static force value for 3 min. The increase in the cross-sectional area of the orthodontic wires disfavors the process of elongation of the sample, at the same applied static force. Using the Multi-Frequency–Strain–Stress modulus, in the tension mode, DMA cyclic heating–cooling measurements were performed. The measured physical quantities for orthodontic wires were Storage Modulus, Loss Modulus, Tanδ and Stiffness, at heating and cooling. Thus, the characteristic temperatures of the phase transitions (A_s, A_f, M_s, M_f), of all the studied orthodontic wires were identified. Also, the values of the elasticity modulus (Young’s Modulus) of the orthodontic wires were calculated at 35 °C. With the DSC Q200 device, using temperature-modulated differential scanning calorimetry method, a multi-step temperature variation program, was applied to a rectangular wire, in three stages (cooling–heating–cooling). Through the interpretation of heat fluxes (reversible, irreversible and total), the phase transitions in the formation of martensite, austenite, but also of the rombohedral phase (R-phase), were identified. Formations of austenite and martensite were also evidenced by the classical DSC method, but the classical DSC method also enabled the R-phase identification. The adherence of some food dyes on the orthodontic wires, as well as the modification of the surface roughness of the orthodontic wire after the deposition of the food dye, was also studied. By magnetic measurements, it was established that the orthodontic wires had paramagnetic properties at room temperature, and nitinol was a mixture of 49.2% austenite and 50.8% martensite.

     

Self-assembled films based on polypyrrole and carbon nanotubes composites for the determination of Diuron pesticide

In this work, polypyrrole (PPy) and its respective composite with functionalized multi-walled carbon nanotubes (MWCNT) were obtained by chemical polymerization of the monomer pyrrole in aqueous solution. The obtained PPy as well as its composite (PPy-MWCNT) were characterized by Fourier transform infrared spectroscopy (FTIR) and were used to produce nanostructured self-assembled (SA) films deposited onto glass substrates covered with indium tin oxide (ITO). The SA films were produced with alternated layers of polystyrene sulphonated (PSS) and were characterized by UV-visible, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) analyses. The applicability of the SA films was evaluated by square wave voltammetry (SWV) with standard additions of aliquots of Diuron pesticide in Britton-Robinson buffer solutions (pH = 2.0). The results showed an oxidation peak at 0.23 V which increases in function of the Diuron concentration for both the SA films. It was also observed that the SA film based on the composite (PPy-MWCNT/PSS) showed a peak current intensity about ten times higher in comparison with its unmodified counterpart (PPy/PSS) for a Diuron concentration of 4.29 × 10^?5 mol L^?1, indicating a synergic effect between PPy and MWCNT in the composite. The limits of quantification (LOQ) and limits of detection (LOD) were respectively 8.6 × 10^?7 mol L^?1 and 2.6 × 10^?7 mol L^?1.