Modification of magnetic anisotropy in metallic glasses using high-energy ion beam irradiation

Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe₄₀Ni₄₀B₂₀ and Fe₄₀Ni₃₈Mo₄B₁₈ metallic glass ribbons. 90 MeV ¹²⁷I beam was used for the irradiations. Irradiation doses were 5×10¹³ and 7.5×10¹³ ions/cm². The relative intensity ratios D ₂₃ of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy.     

Synthesis and herbicidal properties of 3-(2-oxo-1-imidazolidinyliminomethyl)indoles

The reaction of 1-substituted 2-chloroindole-3-carboxaldehydes with 1-amino-2-imidazolidinone gave a series of 1-substituted 2-chloro-3-(2-oxo-1-imidazolidinyliminomethyl)indoles which were evaluated as potential herbicides. The level of biological activity was not sufficient to warrant further investigation.     

New advancements in SERS dye detection using interfaced SEM and Raman spectromicroscopy (μRS)

In the past decade Surface Enhanced Raman Scattering (SERS) has emerged as a powerful technique for the analysis of artistic, historical and archaeological material culture. However, the identification of organic compounds in complex samples using SERS can be challenging owing to the complexity in optimizing the adsorption of target analytes onto the plasmonic substrate and the difficulty to identify proper areas on the sample for robust SERS analysis using optical systems. Scanning electron microscopy (SEM) interfaced with Raman spectromicroscopy (μRS) provides an ideal hyphenated system to overcome the last challenge by: (1) evaluating the nanoparticles coverage/distribution on the sample and (2) locating suitable areas for successful and reproducible SERS analysis. In this paper we demonstrate the potential of a system interfacing SEM and μRS for single fiber, extractionless analysis in the characterization of dyes from reference collections and archaeological textiles. Copyright © 2015 John Wiley & Sons, Ltd.     

The influence of a transverse magnetic field on a subnormal glow discharge in air

In subnormal glow discharge under d.c. excitation at different pressure in a varying transverse magnetic field (0 to 30 G) some measurements have been carried out for various initial average tube currents. The voltage across the discharge increases and average tube current and residual current decreases in the magnetic field. With the help of Beckman’s expression [4] for the axial field and the electron density distribution in a transverse magnetic field the observed variation of current and voltage can be satisfactorily explained. The variation of axial electric field with transverse magnetic field can be represented to a fair degree of accuracy by the derived equation. The behaviour of residual current with magnetic field has been observed in these oscillations.     

A novel approach to improve operation and performance in flow field-flow fractionation

A new system design and setup are proposed for the combined use of asymmetrical flow field-flow fractionation (AF4) and hollow-fiber flow field-flow fractionation (HF5) within the same instrumentation. To this purpose, three innovations are presented: (a) a new flow control scheme where focusing flow rates are measured in real time allowing to adjust the flow rate ratio as desired; (b) a new HF5 channel design consisting of two sets of ferrule, gasket and cap nut used to mount the fiber inside a tube. This design provides a mechanism for effective and straightforward sealing of the fiber; (c) a new AF4 channel design with only two fluid connections on the upper plate. Only one pump is needed to deliver the necessary flow rates. In the focusing/relaxation step the two parts of the focusing flow and a bypass flow flushing the detectors are created with two splits of the flow from the pump. In the elution mode the cross-flow is measured and controlled with a flow controller device. This leads to reduced pressure pulsations in the channel and improves signal to noise ratio in the detectors. Experimental results of the separation of bovine serum albumin (BSA) and of a mix of four proteins demonstrate a significant improvement in the HF5 separation performance, in terms of efficiency, resolution, and run-to-run reproducibility compared to what has been reported in the literature. Separation performance in HF5 mode is shown to be comparable to the performance in AF4 mode using a channel with two connections in the upper plate.     

Tandem hollow-fiber flow field-flow fractionation

Reinjection of one ore more collected fractions of eluted samples is recognized as a useful procedure in analytical separation techniques, among which field-flow fractionation (FFF), to improve the actual separation of complex samples. Hollow-fiber flow FFF (HF5) is a micro-channel subset of flow FFF (F4), which has recently reached a performance comparable to that of standard, flat-channel F4. To further improve HF5 of complex protein samples, we present a new device and method for in-line, reinjection HF5 that we call tandem HF5 (HF5/HF5). HF5 is ideally suited for tandem operation because (1) small channel volume and low operation flow rates allow reducing dilution and volume of the collected fractions, and (2) the relaxation/focusing step that takes place between the 1st and 2nd run (refocusing) allows reestablishing the volume and concentration of the sample plug before the 2nd elution. HF5/HF5 proves particularly effective in the case of oligomeric proteins since it allows collecting and reinjecting the bands that correspond to each separated oligomeric form. This provides information on the dynamic equilibria between the different oligomers. For HF5/HF5 operations, a modified, prototype HF5 instrumentation is presented which includes a "trap" constituted of a four-port, two-way valve positioned downstream the UV detector and a collection loop. The effect of refocusing conditions on HF5/HF5 performance is investigated by varying refocusing time. With a complex protein samples such as blood serum, HF5/HF5 can improve detectability of the low abundance components since overloading effects due to high-abundance components are reduced. This is shown for serum lipoproteins: while after the 1st run high density lipoproteins (HDLs) are not separated from high-abundance serum proteins, after the 2nd run it is shown possible to separate the HDL subclasses.     

Tunable no-tracking OPO-OPA tandem in the near-infrared pumped by a Ti:Sapphire laser

We report the performance of a type-II KTP optical parametric oscillator-amplifier tandem pumped in a non-critical phase-matching configuration by a flashlamp-pumped Ti:Sapphire laser, scanned from 730 to 900 nm. Tunable signal and idler wavelengths are generated from 1.065 to 1.290 µm and from 2.320 to 2.970 µm, respectively, without crystal tracking. Slope efficiency is as high as 32% for the signal conversion only. A KNbO₃ crystal has also been tested as a parametric amplifier in a no-tracking configuration and yields comparable gain.     

New UV tunable solid-state lasers for lidar applications

We present the first lidar/DIAL system based on an Ultra Violet (UV) vibronic laser. A Nd:YAG-pumped Ce:LiSAF laser has been developed for this purpose, providing high pulse energy (5 mJ at 10 Hz), very high slope efficiency (33%), and a tuning range from 284 to 299 nm. Simultaneous measurements of SO₂ and O₃ concentration profiles are presented using this frequency-agile Ce:LiSAF-based lidar system.     

Study of the missing-mass spectra in the reactions π−d → K+ + MM and K−d → π+ + MM at 1.4 GeV/c to search for strange dibaryon states

The reactions π^?d → K⁺ + MM and K^?d → π⁺ + MM have been studied at 1.4 GeV/c to search for strange dibaryon states with quantum numbers Q = ?1, and S = ?1. No structures are found which could indicate the production of such states and upper limits for the cross sections are established.