Nuclear resonant magnetometry and its application to Fe/Cr multilayers

We introduce nuclear resonant magnetometry as a means to record the magnetization curve of isotopically enhanced regions of a sample. It is based on nuclear resonant scattering with circularly polarized synchrotron radiation and the use of a nuclear resonant reference sample. We apply this approach to study the interlayer coupling in Fe/Cr(100) multilayers and to obtain a layer-specific magnetization curve. Our measurements provide experimental evidence for the existence of a nontrivial interlayer-coupling angle in Fe/Cr/Fe.     

Rice straw and energy reed fibers reinforced phenol formaldehyde resin polymeric biocomposites

Cellulose - Herein, natural fiber (energy reeds and rice straw) reinforced with phenol formaldehyde (PF) polymeric resin biocomposites are developed and reported in this study. The dimensions of...     

Simultaneous determination of β-lactamic antibiotics by a new high-performance low-pressure chromatographic system using a multisyringe burette coupled to a monolithic column (MSC)

A technique based on multisyringe chromatography (MSC) was developed to determine three beta-lactamic antibiotics. Amoxicillin (AMOXI), ampicillin (AMPI) and cephalexin (CEPHA) were analyzed using a system with a very simple design and very low-cost equipment consisting of a multisyringe module, three low-pressure solenoid valves, a monolithic Chromolith Flash RP-18e column and a diode array spectrophotometric detector monitoring at 250 nm. Mobile phases containing methanol:acetic acid (0.1 M)-sodium acetate (0.1 M), pH 6.2, were tested for various ratios of methanol:acetic acid-sodium acetate, but a ratio of 10:90 gave optimum results with a flow rate of 2 ml min(-1). Validation parameters were evaluated for amoxicillin. The response to amoxicillin was linear over the range 0.04-0.4 mg/mL, with a correlation coefficient of 0.9996; precisions, evaluated as the repeatability for 0.04, 0.16 and 0.4 mg/mL amoxicillin, were 0.6%, 0.1% and 0.6%, respectively. Recovery from a generic formulation of amoxicillin was evaluated. The method showed selectivity in the presence of excipients commonly used in capsules, and satisfactory specificity was observed for amoxicillin and hydrolytic degradation products. The linearity was also evaluated for cephalexin and ampicillin. The conditions selected for MSC separation were compared with those for a HPLC system, and similar results were obtained in terms of chromatographic parameters but a difference in retention times was observed.     

Synthesis,Spectral, Thermal Studies of Co(II), Ni(II), Cu(II) and Zn(II)‐arginato Complexes. Crystal Structure of Monoaquabis(arginato‐κO,κN)copper(II). [Cu(arg)2(H2O)].NaNO3

Transition metal complexes of arginine (using Co(II), Ni(II), Cu(II) and Zn(II) cations separately) were synthesized and characterized by FTIR, TG/DTA‐DrTG, UV‐Vis spectroscopy and elemental analysis methods. Cu(II)‐Arg complex crystals was found suitable for x‐ray diffraction studies. It was contained, one mole Cu^II and Na⁺ ions, two arginate ligands, one coordinated aqua ligand and one solvent NO₃^? group in the asymmetric unit. The principle coordination sites of metal atom have been occupied by two N atoms of arginate ligands, two carboxylate O atoms, while the apical site was occupied by one O atom for Cu^II cation and two O atoms for Co^II, Ni^II, Zn^II atoms of aqua ligands. Although Cu^II ion adopts a square pyramidal geometry of the structure. Co^II, Ni^II, Zn^II cations have octahedral due to coordination number of these metals. Neighbouring chains were linked together to form a three‐dimensional network via hydrogen‐bonding between coordinated water molecule, amino atoms and O atoms of the bridging carboxylate groups. Cu^II complex was crystallized in the monoclinic space group P2₁, a = 8.4407(5) Å, b = 12.0976(5) Å, c = 10.2448(6) Å, V = 1041.03(10) ų, Z = 2. Structures of the other metal complexes were similar to CuII complex, because of their spectroscopic studies have in agreement with each other. Copper complex has shown DNA like helix chain structure. Lastly, anti‐bacterial, anti‐microbial and anti‐fungal biological activities of complexes were investigated.     

Selective Recognition of Cobalt (II) Ion by a New Cryptand Compound with N2O2S2 Donor Atom Possessing 2-Hydroxy-1-Naphthylidene Schiff Base Moiety

A new cryptand compound carrying 2-hydroxy-1-naphthylidene Schiff base moiety (3) was designed and synthesized by reaction of the corresponding macrobicyclic amine compound (1) and 2-hydroxy-1-naphthaldehyde (2). The influence of metal cations such as Mg²⁺, Ca²⁺, Sr²⁺, Fe²⁺,Co²⁺, Mn²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Al³⁺ and Pb²⁺ on the spectroscopic properties of the new fluoroionophore was investigated in acetonitrile-dichloromethane solution (9.5/0.5) by means of absorption and emission spectrometry. The blue shifts on the fluorescence spectrum were observed for all metal cations at 504nm. At the same time the fluorescence spectrum of the ligand showed quenching in the intensity of the signal at 504 nm for all metal cations except for Zn²⁺. Interaction of Co²⁺ with the ligand caused quenching of naphtyl fluorescence higher than 84%. The method showed good selectivity and sensitivity for Co²⁺ with respect to other metal cations with linear range and detection limit of 1.5 × 10⁻⁷ to 3.3 × 10⁻⁶M and 4.8 × 10⁻⁸M respectively.     

Crystal Structure and Conformational Analysis of 4-[(<Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylamino)Benzylidene]-2-Phenyloxazole-5-One

Abstract  

Molecular and crystal structure of 4-[(p-N,N-dimethylamino)benzylidene]-2-phenyloxazol-5-one, C₁₈H₁₆N₂O₂, have been determined by single crystal X-ray diffraction study. The title compound is monoclinic, with a = 12.1704(23) ?, b = 3.9810(5) ?, c = 30.9603(56) ?, β = 101.176(15)°, Z = 4, D _x = 1.32 g/cm³, μ(Mo Kα) = 0.087 mm⁻¹, and space group is P12₁/c1. The structure was solved by direct methods and refined to a final R = 0.047 for 3166 reflections with I > 2σ(I). The crystal structure is stabilized by C–H⋯O and C–H⋯N type intra-molecular, C–H⋯O type inter-molecular interactions. To enlighten the flexibility and the geometric isomerism (E or Z) of the title compound, the selected torsion angle is varied from −180 to 180° in every 10° separately and molecular energy profile is calculated and analyzed.     

Emission-based optical carbon dioxide sensing with HPTS in green chemistry reagents: room-temperature ionic liquids

We describe the characterization of a new optical CO₂ sensor based on the change in the fluorescence signal intensity of 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) in green chemistry reagents—room-temperature ionic liquids (RTILs). As far as we are aware, this is the first time RTILs, 1-methyl-3-butylimidazolium tetrafluoroborate (RTIL-I) and 1-methyl-3-butylimidazolium bromide (RTIL-II), have been used as matrix materials with HPTS in an optical CO₂ sensor. It should be noted that the solubility of CO₂ in water-miscible ionic liquids is approximately 10 to 20 times that in conventional solvents, polymer matrices, or water. The response of the sensor to gaseous and dissolved CO₂ has been evaluated. The luminescence intensity of HPTS at 519 and 521 nm decreased with the increasing concentrations of CO₂ by 90 and 75% in RTIL-I and RTIL-II, respectively. The response times of the sensing reagents were in the range 1–2 min for switching from nitrogen to CO₂, and 7–10 min for switching from CO₂ to nitrogen. The signal changes were fully reversible and no significant hysteresis was observed during the measurements. The stability of HPTS in RTILs was excellent and when stored in the ambient air of the laboratory there was no significant drift in signal intensity after 7 months. Our stability tests are still in progress.      

International Henry Moseley School and Workshop on X-ray Science

Under the glowing southern Turkish sun, a group of 54 students from eight different countries and 18 teachers from all over the world gathered for 10 days to learn about and discuss the latest developments in the applications of X-rays in different branches of science. The International Henry Moseley School and Workshop on X-ray Science was held at the Institute of Theoretical and Applied Physics in Turunç, Turkey, from June 14 to 23, 2012.