NQS

About: NQS is a research topic. Over the lifetime, 337 publications have been published within this topic receiving 4226 citations.

Determination and Validation of an LC Method for Fluvoxamine in Tablets

Abstract: A new, simple, rapid and specific reversed-phase high-performance liquid chromatography (HPLC) method was developed and validated for the determination of fluvoxamine in pharmaceutical dosage forms. The HPLC separation was achieved on a C18 μ-Bondapack column (250 mm × 4.6 mm) using a mobile phase of acetonitrile–water (80:20, v/v) at a flow rate of 1 mL min−1. Proposed method is based on the derivatization of fluvoxamine with 1,2-naphthoquinone-4-sulphonic acid sodium salt (NQS) in borate buffer of pH 8.5 to yield a orange product. The HPLC method is based on measurement of the derivatized product using UV-visible absorbance detection at 450 nm. The method was validated for specificity, linearity, precision, accuracy, robustness. The degree of linearity of the calibration curves, the percent recoveries of fluvoxamine, the limit of detection and quantification, for the HPLC method were determined. The assay was linear over the concentration range of 45–145 ng mL−1 (r = 0.9999). Limit of detection and quantification for fluvoxamine were 15 and 50 ng mL−1, respectively. The results of the developed procedure (proposed method) for fluvoxamine content in tablets were compared with those by the official method. The method was found to be simple, specific, precise, accurate, reproducible and robust.

Verilog-A modeling of BJT NQS excess phase

Abstract: This paper presents a novel Verilog-A model that implements an idealized frequency dependent phase shift (excess-phase) in the small-signal transconductance but, unlike previous approaches, introduces no magnitude dependence. It has been claimed that Verilog-A cannot model BJT NQS behavior when the delay time depends on bias. We also introduce a new Verilog-A model that provides a correct implementation of bias dependent NQS effects for BJTs.

Bondi mass in the NQS gauge

Abstract: We analyse the asymptotic structure of the gravitational field in null quasi-spherical (NQS) coordinates, and show that the Bondi mass is well-defined and satisfies the Trautman–Bondi mass-loss formula along an outgoing null hypersurface, assuming only a rather weak decay condition on the intrinsic geometry of the hypersurface.

A charge-conserving non-quasistatic MOSFET model for SPICE transient analysis

Abstract: An analytic charge-conserving nonquasistatic (NQS) model has been derived for long-channel MOSFETs and implemented in SPICE3. It is based on an approximate solution to the current-continuity equation. Comparison has been made among this model, the numerical solution to the 1-D current-continuity equation, and the quasistatic (QS) SPICE models. The charge injection at the turnoff transient of a NMOS switch has been simulated using this model and conventional QS models, and it has been found that the QS models give inaccurate results even for the moderately short channel (3- mu m) MOSFETs when the input voltage is changing at the moment of turnoff. A differential sample-hold circuit has also been simulated using this model, and the results are compared with those from QS models. The CPU time using this model is around 3 to 4 times longer than for the conventional QS SPICE models. >