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21.
We report the results of our investigation of magnetization and heat capacity on a series of compounds CeYxNiGe2 () under the influence of external magnetic field. Our studies of the thermodynamic quantity on these compounds indicate that magnetic frustration persists in Ce0.9Y0.1NiGe2, as also reported for the parent compound CeNiGe2. The weak signature of this frustration is also noted in Ce0.8Y0.2NiGe2, whereas, it is suppressed in Ce0.6Y0.4NiGe2. Heat capacity studies on Ce0.9Y0.1NiGe2 and Ce0.8Y0.2NiGe2 indicate the presence of a new magnetic anomaly at high field which indicates that quantum criticality is absent in these compounds. However, for Ce0.6Y0.4NiGe2 such an anomaly is not noted. For this later compound, the magnetic field (H) and temperature (T) dependence of heat capacity and magnetization obey scaling above critical fields. However, the obtained scaling critical parameter (δ) is 1.6, which is away from mean field value of 3. This deviation suggests the presence of unusual fluctuations and anomalous quantum criticality in these compounds. This unusual fluctuation may arise from disorderness induced by Y-substitution. 相似文献
22.
Thirupathi Dongala Naresh Kumar Katari Ashok Kumar Palakurthi Sreekantha B. Jonnalagadda 《Biomedical chromatography : BMC》2019,33(10)
We developed novel stability‐indicating HPLC method for simultaneous estimation of 14 impurities in excedrin tablet, a formulation with a combination of acetaminophen, aspirin, and caffeine. In addition, a new impurity that was generated through degradation of aspirin at high temperatures during the accelerated stability conditions was positively identified and confirmed, using liquid chromatography–mass spectrometry technique. The HPLC method was optimized using the Inertsustain C18, 250 × 4.6 mm, 5.0 μm column, employing simple gradient method. Forced degradation studies were performed under acidic, basic, oxidative and thermal conditions to prove the scope and stability‐indicating the nature of the method. The optimized method was validated as per the International Conference on Harmonization guidelines. The HPLC method showed linearity from LOQ concentration to 21 μg mL?1. Precision and intermediate precision values were <5% RSD. The validated HPLC method is currently applied for the routine testing of excedrin tablet formulations in quality control laboratories. 相似文献
23.
Saurabh B. Ganorkar Suraj R. Chaudhari Preeti S. Bobade Sagar H. Pawar Atul A. Shirkhedkar 《Biomedical chromatography : BMC》2022,36(5):e5345
Rufinamide is used presently to treat Lenaux–Gastaut syndrome. A full factorial design and desirability approach was investigated for the optimization of hydrolytic stress via response surface curves (RSCs). The degradation impurities were identified and resolved using reversed-phase high-performance liquid chromatography (RP-HPLC) on the Qualisil® BDS C8 column. Acetonitrile–water (29:71, v/v) was optimized for the mobile phase and used at a flow rate of 1.0 ml/min with detection at a wavelength of 230 nm. Rufinamide showed appreciable susceptibility to hydrolysis under acidic and alkaline stress, and substantial degradation in the neutral condition. It degraded much less under oxidative stress. Exposure towards thermal and photolytic stress conditions indicated appreciable stability. The developed method was subjected to validation as per the recommendations of the International Conference on Harmonization. The proposed method showed no influence from the excipients and the degradation products. As well as good precision and accuracy in determination, the method showed a linear response between 2 and 12 μg ml−1. The method was extended for determination in a human plasma sample, which resulted in excellent recovery without interference from matrix effects. The combined use of desirability and design for the optimization of acidic and alkaline hydrolytic stress led to simple and rapid analysis. 相似文献
24.
Amitabh Jain 《辐射效应与固体损伤》2013,168(1-4):39-46
The potential advantages of ion implantation have been exploited in virtually every kind of semiconductor device. Several commercially important devices owe their existence to this technique. Ion implantation provides precise control over the amount of dopant, concentration profile and lateral dimensions in device fabrication. The high degree of uniformity and reproducibility have made it possible to produce sophisticated devices and integrated circuits with high yield and tight tolerances. This is a truly planar process. It is possible to achieve high doping concentrations with relatively lower processing temperatures thereby avoiding lifetime degradation. The process is carried out in an inherently clean environment. A wide range of dopants is available and one is not limited by the particular properties of the substrate. There is great flexibility in choice of masking materials and self-alignment of doped regions in MOS devices is facilitated. The increasing impact of ion implantation on device technology is discussed with reference to some recent developments. Specific commercially manufactured devices are mentioned. Ion implantation machines continue to undergo development aimed at higher throughputs and cleaner vacuum. There is the need for greater reliability of machines. Effort is also directed at the development of low cost machines for dedicated applications. Design of implanted devices continues to be an empirical process in some respects. The ability to accurately predict profile shapes in samples implanted (perhaps through a screen oxide) and subject to complicated post-implantation process steps, would cut down development time and costs. 相似文献
25.
Ein Bericht über die aktivierungsanalytische Bestimmung des Cu, Au, Ir, Os und Ru in Platin durch radiochemische Trennung und gammaspektrometrische Strahlungsmessung. Aufbau eines radiochemischen Trenungsganges durch Verflüchtigung der Tetroxide des Os und Ru, Beseitigung der Matrixaktivität durch Adsorption am Anionenaustauscher, Extraktion des Au, Cu u. a. Elemente als Chloro-, DDTC- und BPHA-Komplexe. Diskussion der Möglichkeiten für den Einsatz des Trennungsganges in der Aktivierungsanalyse. Wiedergabe der Arbeitsvorschrift und der Ergebnisse der Analyse einiger Platinproben mit Verunreinigungen im Bereich von 0,05…400 ppm. 相似文献
26.
27.
Divya Kumar Vemuri Rambabu Gundla Naresh Konduru Ravindra Mallavarapu Naresh Kumar Katari 《Biomedical chromatography : BMC》2022,36(6):e5363
Favipiravir finished dosage was approved for emergency use in many countries to treat SARS-CoV-2 patients. A specific, accurate, linear, robust, simple, and stability-indicating HPLC method was developed and validated for the determination of degradation impurities present in favipiravir film-coated tablets. The separation of all impurities was achieved from the stationary phase (Inert sustain AQ-C18, 250 × 4.6 mm, 5-μm particle) and mobile phase. Mobile phase A contained KH2PO4 buffer (pH 2.5 ± 0.05) and acetonitrile in the ratio of 98:2 (v/v), and mobile phase B contained water and acetonitrile in the ratio of 50:50 (v/v). The chromatographic conditions were optimized as follows: flow rate, 0.7 mL/min; UV detection, 210 nm; injection volume, 20 μL; and column temperature, 33°C. The proposed method was validated per the current International Conference on Harmonization Q2 (R1) guidelines. The recovery study and linearity ranges were established from the limit of quantification to 150% optimal concentrations. The method validation results were found to be between 98.6 and 106.2% for recovery and r2 = 0.9995–0.9999 for linearity of all identified impurities. The method precision results were achieved below 5% of relative standard deviation. Forced degradation studies were performed in chemical and physical stress conditions. The compound was sensitive to chemical stress conditions. During the study, the analyte degraded and converted to unknown degradation impurities, and its molecular mass was found using the LC–MS technique and established degradation pathways supported by reaction of mechanism. The developed method was found to be suitable for routine analysis of research and development and quality control. 相似文献
28.
Jyoti Kannoujia Pavan Kumar Bangalore Srinivas Kantevari Prabhakar Sripadi 《Journal of mass spectrometry : JMS》2020,55(10)
The HPLC‐DAD and GC/MS methods were successfully used for the identification and characterization of the impurities in an agrochemical insecticide, bifenthrin technical. Three impurities ranging from 0.175%–0.541% were detected by the HPLC‐DAD method. The LC/MS technique with ESI or APCI source failed to detect the impurities detected by HPLC‐DAD, due to lack of ionization in ESI or APCI. The three impurities were enriched by prep‐HPLC, and then their structures were elucidated based on the GC/EIMS and CIMS data. The EI mass spectra of bifenthrin and its impurities displayed molecular ion and provided structure indicative fragment ions; the CIMS data further confirmed their molecular weight. The identity of the impurity 1 was further confirmed by the synthesis of the authentic sample followed by NMR and GC/MS data. 相似文献
29.
Isobaric tagging reagents such as isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tag (TMT) typically have isotopic impurities that cause significant cross‐talk between channels. Here, we present an efficient solution to compensate for channel cross‐talk using linear algebra and find that it is between 20× and 120× faster than previous methods. We also find that the effects of channel cross‐talk are as important to manage as the effects of ratio compression because of precursor impurities, and we have released an open‐source tool to perform both types of calculations. 相似文献
30.
We theoretically study complementarity between micro-micro and micro-macro entanglement in a Bose–Einstein condensate with two Rydberg impurities. We investigate quantum dynamics of micro-micro and micro-macro entanglement in the micro-macro system. It is found that strong micro-macro entanglement between Rydberg impurities and the BEC can be generated by the use of initial micro-micro entanglement between two Rydberg impurities, which acts as the seed entanglement to create micro-macro entanglement. We demonstrate a curious complementarity relation between micro-micro and micro-macro entanglement, and find that the complementarity property can be sustained to some extent even though in the presence of the BEC decoherence. 相似文献