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1.
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. 相似文献
2.
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. 相似文献
3.
A simple two-step synthesis of an air-stable hexaammoniumtriptycene is introduced, which can be used for a variety of transformations by condensation reactions, e.g., to benzimidazole, benzotriazole, and quinoxaline derivatives in high yields. 相似文献
4.
Martins LA Meneghini LZ Junqueira CA Ceni DC Bergold AM 《Journal of chromatographic science》2011,49(10):796-800
A simple stability indicating high-performance liquid chromatography method for the analysis of adapalene in pharmaceutical gel formulation is developed and validated. An isocratic separation is performed using a Merck RP-8 (150 mm × 4.6 mm i.d., particle size 5 m) column and a mixture of acetonitrile water (67:33, v/v, pH adjusted to 2.5 with phosphoric acid) as the mobile phase. The detection is achieved with a photodiode array detector at 321 nm. The specificity of the method is verified by subjecting both the reference substance and the pharmaceutical form to hydrolytic, oxidative, photolytic, and thermal stress conditions. There is no interference from the excipients of the formulation on the determination of adapalene in gel. The response is linear over the concentration range of 8.0-16.0 μg/mL (r > 0.999) with a limit of detection and quantification of 0.04 and 0.14 μg/mL, respectively. The mean recovery is 100.8%. The RSD values for the intra- and inter-day precision studies are < 1.2%. The method is validated by reaching satisfactory results for linearity, selectivity, specificity, precision, accuracy, robustness, and system suitability. 相似文献
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DC Muddiman AP Null JC Hannis 《Rapid communications in mass spectrometry : RCM》1999,13(12):1201-1204
Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) has been used to determine the mass of a double-stranded 500 base-pair (bp) polymerase chain reaction (PCR) product with an average theoretical mass of the blunt-ended (i.e. unadenylated) species of 308 859.35 Da. The PCR product was generated from the linearized bacteriophage Lambda genome which is a double-stranded template. Utilization of ethanol precipitation in tandem with a rapid microdialysis step to purify and desalt the PCR product was crucial to obtain a precise mass measurement. The PCR product (0.8 pmol/μL) was electrosprayed from a solution containing 75% acetonitrile, 25 mM piperidine, and 25 mM imidazole and was infused at a rate of 200 nL/min. The average molecular mass and the corresponding precision were determined using the charge-states ranging from 172 to 235 net negative charges. The experimental mass and corresponding precision (reported as the 95% confidence interval of the mean) was 309 406 +/- 27 Da (87 ppm). The mass accuracy was compromised due to the fact that the PCR generates multiple products when using Taq polymerase due to the non-template directed 3'-adenylation. This results in a mixture of three PCR products with nearly identical mass (i.e. blunt-ended, mono-adenylated and di-adenylated) with unknown relative abundances that were not resolved in the spectrum. Thus, the experimental mass will be a weighted average of the three species which, under our experimental conditions, reflects a nearly equal concentration of the mono- and di-adenylated species. This report demonstrates that precise mass measurements of PCR products up to 309 kDa (500 bp) can be routinely obtained by ESI-FTICR requiring low femtomole amounts. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
7.
DC Bassett 《Macromolecular Symposia》1997,114(1):121-126
Molecular cilia, the uncrystallized portions of chains already partly attached to polymer crystals, exert a profound influence on the course of polymeric crystallization with ultimate responsibility for the divergence of adjacent lamellae which leads to spherulitic growth. Their effective size and pressure have been measured, in α-polypropylene, from electron microscopic measurements of the separation and maximum curvature of lamellae in row structures. That cilia exist and extend the effective region occupied by a lamella beyond the geometrical confines of its fold surfaces is important for crystallization theory and may well have implications for the connection of lamellae into networks and for gelation. 相似文献
8.
Reversed-phase liquid chromatography (LC) and LC/tandem mass spectrometry (LC/MS/MS) methods were developed and validated for the determination of etoricoxib in pharmaceutical dosage forms. The LC method was performed by reversed-phase chromatography on a Synergi fusion C18 column (150 x 4.6 mm id) maintained at ambient temperature. The mobile phase consisted of 0.01 M phosphoric acid, pH 3.0-acetonitrile (62 + 38, v/v) at a flow rate of 1.0 mL/min, and photodiode array detection at 234 nm was used. The chromatographic separation was obtained within 7.0 min, and calibration curves were linear in the concentration range of 0.02-150 microg/mL. The LC/MS/MS method was performed on a Luna C18 column (50 x 3.0 mm id). The mobile phase consisted of acetonitrile-water (95 + 5)-0.1% acetic acid (90 + 10, v/v). Detection was performed by positive electrospray ionization in the multiple reaction monitoring mode, monitoring the transitions 359.3 > 280.0 and 332.0 > 95.0 for etoricoxib and piroxicam (internal standard), respectively. The chromatographic separation was obtained within 2.0 min, and calibration curves were linear in the concentration range of 1-5000 ng/mL. Validation parameters, such as specificity, linearity, precision, accuracy, and robustness, were evaluated, which gave results within the acceptable range for both methods. Moreover, the proposed methods were successfully applied for routine quality control analysis of pharmaceutical products and showed significant correlation (r = 0.9999) of the results. 相似文献
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R. W. Woittiez A. Lagerwaard K. J. Volkers M. DC. Tangonan 《Journal of Radioanalytical and Nuclear Chemistry》1993,169(1):229-237
The use of ion chromatography with continuous UV detection for radiochemical separation of Cr with simultaneous yield determination is presented. The RNAA method consists of sample destruction in HNO3+HClO4, extraction of Cr(VI) with tribenzylamine in CHCl3, backextraction in NaOH and chromatography of chromate. From radiotracer experiments, the ratio of signals for51Cr and Cr spike was found to be constant for a chromium mass range of 15 to 100 g. Application of the RNAA method to Cr determination in biological reference materials showed a reasonable agreement with the reference values. A relative standard deviation of 3% on the 100 g/kg level for homogeneous material was achieved.IAEA-fellow, on leave from the Philippine Nuclear Research Institute Philippine 相似文献