Janko Luznik

Polarization enhanced 14N NQR detection with a nonhomogeneous magnetic field

Abstract The use of proton polarization enhancement of low frequency 14 N NQR signals was tested. An improvement of NQR signals was observed in samples of (N 3 (NO 2 ) 3 (CH 2 ) 3 , (CH 2 ) 6 N 4 and (NO 2 )C 6 H 4 COOH). A very nonhomogeneous magnetic field obtained with a permanent magnet was used for proton polarization.

Application of 14N NQR to the Study of Piroxicam Polymorphism

A study was conducted to test the capability of the (14)N nuclear quadrupole resonance (NQR) method to discriminate qualitatively and quantitatively among different forms of piroxicam. Samples of commercial piroxicam form I and its monohydrate were obtained on the local market. Additionally, samples of form I and II were prepared by recrystallization in 1,2-dichloroethane and ethanol, respectively. DSC and FT-IR were employed as reference methods. A (14)N NQR spectrometer was used to measure samples of different forms and mixtures of piroxicam at 2587 and 3439  kHz. DSC and FT-IR clearly confirmed differences between the different piroxicam forms. Measurements of (14)N NQR signals of different forms of piroxicam at 2587  kHz detected only spectral peaks of form I. The dependence of (14)N NQR signal intensity on the concentration of form I in mixtures with the monohydrate showed a clear linear relationship at both measured frequencies, though the scattering of data was greater at 3439  kHz due to the lower S/N ratio. The (14)N NQR method has the potential to become an additional and important spectroscopic tool in the study of solid-state forms, not only of pure active pharmaceutical ingredients or excipients, but also of their mixtures. This ability lends the method to a possible successful utilization at different levels of pharmaceutical manufacturing and product quality control.

Influence of different presentations of oscillometric data on automatic determination of systolic and diastolic pressures.

Most non-invasive blood pressure measurements are based on either the auscultatory or the oscillometric technique. In this study, we performed an extensive analysis of the signals, i.e., responses of a microphone implanted in the cuff and pressure changes in the cuff, which can be recorded during such measurements. We applied several methods to separate the cuff deflation from the arterial pressure pulses, as well as to separate the microphone data into an audible part (Korotkoff sounds) and a low frequency part. The oscillometric technique is based on some empirically derived criteria applied to the oscillometric index, which is defined as a certain characteristic physical property of pressure pulses. In addition to the pressure pulses, which are a typical physical property used for the oscillometric index, we also used in this study other properties such as a time derivative and an audible part of data measured by a microphone implanted in the cuff (Korotkoff sounds). We performed a case study of 23 healthy subjects to evaluate the influence of different presentations of the oscillometric index on known height-based and slope-based empirical algorithms for the automatic determination of the systolic and diastolic blood pressures.

Chlorine NQR in normal and deuterated (CH3)4N(CCl3COO)2H

Abstract 35 Cl NQR in normal and deuterated (CH 3 ) 4 N(CCl 3 COO) 2 H - tetramethyl-amnonium hydrogen bis-trichloracetate (THB) was measured as a function of temperature in the region from 77 K to 518 K. These measurements together with the measurements of the real part of the dielectric constant in the same temperature interval confirmed the existance of three phases in THB. It was also observed, that the metastable phases exist in THB. From the chlorine NQR data it seems that the hydrogen bond is asymmetric in normal and in deuterated THB.

Enhancement of oscillometric index in non-invasive blood pressure measurements

Most non-invasive blood pressure measurements are based on either the auscultatory or the oscillometric technique. The oscillometric technique is based on some empirically derived criteria applied to the oscillometric index, which is defined as a certain characteristic physical property of pressure pulses. In this study, we introduced a new type of enhanced oscillometric index obtained by a powered short time variance of the pressure data. Such a presentation shows significant activity only below the systolic and above the diastolic blood pressure, which simplifies the criteria for automatic determination of blood pressure values, i.e., as in the case of the auscultatory technique, where only the presence and absence of pulses has to be detected.

Influence of different representations of the oscillometric index on automatic determination of the systolic and diastolic blood pressures

The oscillometric technique of non-invasive blood pressure measurement is based on some empirically derived criteria applied to the so-called oscillometric index, defined as a certain characteristic physical property of the arterial pressure pulses. The aim of this study is to evaluate the influence of different representations of the oscillometric index on the known height based and slope based empirical algorithms for automatic determination of systolic and diastolic blood pressures.