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NQS
About: NQS is a research topic. Over the lifetime, 337 publications have been published within this topic receiving 4226 citations.
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01 Jan 2011
TL;DR: Two simple, extraction free spectrophotometric methods (Method-1 and 2) for the quantitative estimation of pregabalin (PGB) in bulk drugs and pharmaceutical formulations (Capsules) have been developed as mentioned in this paper.
Abstract: Two simple, extraction free spectrophotometric methods (Method-1 and 2) for the quantitative estimation of pregabalin (PGB) in bulk drugs and pharmaceutical formulations (Capsules) have been developed. The first method is based on the condensation of pregabalin with 1, 2- napthaquinone-4- sulfonic acid sodium (NQS) in alkaline media to yield orange colored products. Pregabalin at its λmax 485 nm shows linearity in the concentration range of 5- 45μg/ml. The first method is based on the oxidation of 2, 4- dinitrophenylhydrazine (2, 4-DNP) and coupling of the oxidized product with drugs to give intensely colored chromogen. Condensed product of pregabalin at its λmax 461 nm shows linearity in the concentration range of 50-450 μg/ml. The relative standard deviations were 0.487% and 0.25% respectively for 2 methods. Linear relationships with good correlation coefficients (0.993-0.998) were found between absorbance and the corresponding concentrations of the drug. The reliability and performance of the proposed methods was validated statistically. Percentage recovery ranged from 100.5 and 99.867 respectively.
7 citations
TL;DR: In this article, a novel method was established to determine cefotaxime by using sodium 1,2-naphthoquinone-4-sulfonate (NQS) as a chromogenic reagent.
Abstract: A novel method is established to determine cefotaxime by using sodium 1,2-naphthoquinone-4-sulfonate (NQS) as a chromogenic reagent. A russety product can be formed owing to the nucleophilic substitution reaction between cefotaxime and NQS in 0.1 M solution of NaOH. The maximal absorption wavelength of the product is 489 nm. Absorbance is linear with the concentration of cefotaxime in the range of 3.8–114.6 mg/L, and the regression equation is A = 0.04481 + 0.00567c (mg/L), with a correlation coefficient of 0.9992. The detection limit and the RSD are 3 mg/L and 1.2%, respectively. The average recovery is in the range of 98.9–101.2%. The results indicate that the method could be applied to the determination of cefotaxime in injection.
7 citations
TL;DR: The underlap technique improves the gate electrostatic integrity which in turn improves the analog performance of the device with the help of technology computer-aided design (TCAD) simulation, calibrated with Schrodinger-Poisson solver and experimental results.
7 citations
TL;DR: Furano-naphthoquinones (FNQs), which is a class of NQ characterized by the incorporation of an additional furan ring, have demonstrated improved anti-cancer potency as compared to the other classes of NZs.
Abstract: BACKGROUND Cancer is a leading cause of mortality in the world and metastasis is to blame. A number of naphthoquinones (NQs) have shown ability to reduce cancer stemness and metastatic potential. Furano-naphthoquinones (FNQs), which is a class of NQ characterized by the incorporation of an additional furan ring, have demonstrated improved anti-cancer potency as compared to the other classes of NQs. OBJECTIVE In this study, the natural origins, synthetic routes and derivatives of migrastatic NQs were reviewed. The anti-invasive and anti-metastatic mechanisms of NQs and the more powerful FNQs in targeting cancer were also discussed. METHODS The articles related to the anti-invasive mechanisms of NQs were comprehensively reviewed. The plant origins, synthetic routes and antitumor effects of more than 360 FNQs were also covered and presented according to their chemical structures. RESULTS Anti-cancer NQs inhibit cancer invasion by acting on epithelial-mesenchymal transition (EMT), cancer stem cells (CSCs) and signal transducer and activator of transcription 3 (STAT3) signaling. BBI608, a natural FNQ, has entered phases I and II clinical trials. It has been regarded as a potential candidate for new-generation lead compound acting directly on CSCs to overcome the problem of chemotherapy resistance. Apart from the plant-derived FNQs, there are a number of synthetic FNQs that were found to intervene in cancer invasion and metastasis. CONCLUSION The anti-invasive mechanisms of NQs have been thoroughly studied. FNQs generally show higher anti-cancer activity than that of NQs. The mechanisms of action of FNQs are worth further investigation.
7 citations
11 Dec 2014
TL;DR: In this paper, the authors developed an extended π-equivalent circuit (EC) model to accurately predict the lateral non-quasi-static effects in silicon germanium heterojunction bipolar transistors.
Abstract: Detailed formulations for DC and AC emitter current crowding are presented in view of developing an extended π-equivalent circuit (EC) model to accurately predict the lateral non-quasi-static effects in silicon germanium heterojunction bipolar transistors. Under negligible DC current crowding, the EC reduces to a simple π-model. The implementation-suitable versions of the models are also developed. Compared to state-of-the-art model formulations, the extended π-model shows better accuracy in predicting device simulated data. If desired, the high level of accuracy obtained by the extended π-model can be traded with the required extra simulation time due to one extra node.
7 citations