Room temperature soft ferromagnetism in the nanocrystalline form of YCo2 - a well-known bulk Pauli paramagnet

The Laves phase compound, YCo2, is a well-known exchange-enahnced Pauli paramagnet. We report here that, in the nanocrystalline form, this compound interestingly is an itinerant ferromagnet at room temperature with a low coercive-field. The magnitude of the saturation moment (about 1 Bohr-magneton per formula unit) is large enough to infer that the ferromagnetism is not a surface phenomenon in these nanocrystallites. Since these ferromagnetic nanocrystallines are easy to synthesize with a stable form in air, one can explore applications, particularly where hysteresis is a disadvantage

Experimental studies of spontaneous emission from dopants in an absorbing dielectric

We report the first measurements, to our knowledge, of the modification of spontaneous emission rates of Eu3+ ions in the visible region owing to an absorbing medium. Precise levels of the absorption coefficient are introduced by codoping with different amounts of Nd3+. We use a binary glass system PbO-B2O3 as the host, the compositional variation of which leads to a change in the real part of the refractive index. Measured lifetimes are found to follow the real cavity model, and the data are analyzed by the model proposed by Scheel et al. [Phys. Rev. A 60, 4094 (1999)]. We give estimates of the parameter that is related to the radius of the cavity around Eu3+

Measurement of local field Effects of the host on the lifetimes of embedded emitters

We report experimental results on the variation of the radiative lifetime of Eu3+ ion embedded in a dielectric with the refractive index n. We dope 1 mol % of Eu3+ into the binary glass system xPbO-(1-x)B2O3. By varying x we have achieved a fairly large variation of the refractive index from 1.7 to 2.2. This enables us to study the local field effects for the first time for ions doped in a solid glassy material. Our measurements are in agreement with the so-called real cavity model. The present measurements are free from the complications arising from reorganizational effects in solvents

Griffiths phase-like behaviour and spin-phonon coupling in double perovskite Tb2_{2}NiMnO6_{6}

The Griffiths phase-like features and the spin-phonon coupling effects observed in Tb$_2$NiMnO$_6$ are reported. The double perovskite compound crystallizes in monoclinic $P2_1/n$ space group and exhibits a magnetic phase transition at $T_c \sim$ 111 K as an abrupt change in magnetization. A negative deviation from ideal Curie-Weiss law exhibited by 1/$\chi(T)$ curves and less-than-unity susceptibility exponents from the power-law analysis of inverse susceptibility are reminiscent of Griffiths phase-like features. Arrott plots derived from magnetization isotherms support the inhomogeneous nature of magnetism in this material. The observed effects originate from antiferromagnetic interactions which arise from inherent disorder in the system. Raman scattering experiments display no magnetic-order-induced phonon renormalization below $T_c$ in Tb$_2$NiMnO$_6$ which is different from the results observed in other double perovskites and is correlated to the smaller size of the rare earth. The temperature evolution of full-width-at-half-maximum for the {\it stretching} mode at 645 cm$^{-1}$ presents an anomaly which coincides with the magnetic transition temperature and signals a close connection between magnetism and lattice in this material.Comment: 17 pages, 8 figures; accepted in J. Appl. Phy

A qualitative test for the determination of isoniazid acetylator phenotype

A qualitative test procedure for phenotyping isoniazid acetylators is described. It is based on a colour reaction which depends on the free sulphadimidine content in the total urine excreted over any one-hour period between 21 and 26 hours following a dose of sulphadimidine 1.0 or 1.5 g. depending on body-weight. The test correctly classified 96 per cent of 109 slow and 96 per cent of 68 rapid inactivators. Storage of urine samples at room-temperature up to 14 days did not affect the accuracy of the results

A low-cost Raman spectrometer design used to study Raman scattering from a single-walled carbon nanotube

The paper discusses the design of a low cost Raman spectrometer. Singlewalled Nanotubes (SWNT) have been studied to demonstrate the reach of such a system. We observe both the Radial-breathing Mode (RBM) and the tangential mode from the SWNT. The tube diameters of the SWNT used in these experiments have been determined using RBM to be predominantly 1.4 and 1.6 nm. These are consistent with the TEM images taken of the same sample. The new method of producing SWNT using Ni-Y catalyst in electric-arc discharge method produces nanotubes with very small dispersion in diameter and high yields. The chirality of the SWNT can be deduced from their radial breathing modes and it suggests that they are metallic in nature

Effect of Prednisolone and Rifampin on Isoniazid Metabolism in Slow and Rapid Inactivators of Isoniazid

The effect of prednisolone and rifampin, alone and in combination, on the biodisposition of isoniazid in slow and rapid inactivators of isoniazid was investigated. In one investigation, we made serial determinations of plasma isoniazid concentrations up to 8 h and of isoniazid and acetylisoniazid in excreted urine up to 8.5 h in patients receiving isoniazid alone on one occasion and isoniazid plus prednisolone or isoniazid plus rifampin on another. Prednisolone caused a significant decrease in the plasma isoniazid concentrations in both slow and rapid inactivators. It also enhanced the renal clearance of isoniazid in both slow and rapid inactivators and increased the rate of acetylation of isoniazid in slow inactivators only. Rifampin had no effect on the biodisposition of isoniazid in either slow or rapid inactivators. In a second investigation, one group of slow and rapid inactivators received isoniazid and rifampin, and a different group received prednisolone, in addition. Plasma isoniazid concentrations in slow inactivators receiving prednisolone were significantly lower than in those who received isoniazid and rifampin only. In rapid inactivators, plasma isoniazid concentrations were similar in the two groups of patients, suggesting that concomitant administration of rifampin had considerably modified the prednisolone effect on the biodisposition of isoniazid in these patients

Self-induction of rifampicin metabolism in man

Self-induction of rifampicin metabolism caused by daily administration of the drug was studied in 7 healthy subjects. Rifampicin 600 mg was administered daily for 10 days and additional doses were administered on the 4th and 8th days after drug administration ceased. The mean serum half-life of rifampicin decreased from 4.9 h on the 1st day to 3.5 h on the 4th day (P<0.01), to 2.7 h on the 7th day (P<0.001), and 2.5 h on the 10th day (P<0.001). The difference between the mean values on the 7th and the 10th days was not significant. The mean value on the 8th day after stopping drag administration (3.8 h), was significantly higher than that on the last day of daily administration (P=0.02), but was still lower than that on the 1st day (P=0.05). There was a decrease in the excretion of both rifampicin and desacetylrifampicin in urine on induction, followed by a gradual return to normal when drug administration was stopped

Determination of Acetylator Phenotype Based on the Ratio of Acetylisoniazid to Isoniazid in Urine Following an Oral Dose of Ordinary Isoniazid

A simple method for classifying subjects as slow or rapid inactivators of isoniazid has been described. A uniform dose of 300 mg. of ordinary isoniazid was administered orally to 150 patients with pulmonary tuberculosis. The ratio of acetylisoniazid to isoniazid was determined in urine collected at hourly intervals from 4 to 8 h. At each hour the distribution of the ratios was clearly bimodal. The test based on the 5-6 h. urine collection is recommended for its convenience and excellent discrimination between slow and rapid inactivators. The agreement between this method and a ‘standard method was of the order of 97 per cent