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In this research study, we developed a new rapid and simple HPLC quantitative approach for comprehensively measuring related substance impurities (LNGN N formyl; LNGN acetamide; LNGN N Boc; LNGN amino) in Linagliptin. The related substance impurities were studied by PDA detection at 225 nm after being separated on the Kromasil C18 column stationary phase. The isocratic mode elution and a flow velocity of 1.0 mL/min were performed with the 0.1% phosphoric acid having pH 2.5 and acetonitrile. The proposed approach was appropriately verified in agreement with the "International Conference on Harmonization". Linearity was demonstrated for values ranging from LOQ quantity ppm to 150% quantity ppm, with variance coefficients 0.99. The precision varied from 0.128 to 0.969% RSD and accuracy varied from 99.13% to 101.76% for four related substance impurities. The proposed approach was appropriately implemented in the quality control analysis of the linagliptin API. Stress testing on the linagliptin API is also part of this investigation. One degradant with a 10.273 min Rt was found during oxidative stress testing on linagliptin. Using LC-MS this peak was discovered to be an adduct. [ABSTRACT FROM AUTHOR]

Toward achieving control over the kerfing through macro abrasive waterjet submerged milling, there is a need (i) to understand the influence of the water column height on the kerf quality and (ii) to develop a model for the prediction of the kerf characteristics. This study performs detailed experimentation to assess the kerf quality enhancement in submerged milling relative to the in-air milling on Al-6061 alloy. From the modeling perspective, there are very limited efforts in developing a comprehensive model that includes both the jet flow dynamics and material removal models-this is the missing link. Toward this, a comprehensive model is proposed and validated for the prediction of kerf in in-air and submerged conditions by considering (i) jet dynamics and (ii) jet-material interaction. From the experimental results, it is observed that by adopting the submerged milling, the damaged region, top kerf width and edge radius got reduced by 20.3%, 13.53%, and 22.7%, respectively. However, this enhancement in the kerf quality is associated with a reduction in the centerline erosion depth (hmax) by 12.33% and a material removal rate by 24.52%. The material removal mechanism is more uniform and directed in the submerged milling, whereas in-air is random. The proposed model predicted the kerf cross-sectional profile in submerged milling and in-air with a mean absolute error of 60 µm and 57 µm, squared Pearson correlation coefficient of 0.97 and 0.99, and the hmax with a maximum error of 1.3% and 1.4%. [ABSTRACT FROM AUTHOR]

Underwater sensor networks (USNs) play a key role for applications such as underwater defense, underwater imaging, internet of underwater things, underwater navigation and so on. In USNs, acoustic waves have been referred over the radio frequency (RF) waves or optical waves to communicate between sensor nodes, buoys, and autonomous underwater vehicles (AUVs). The acoustic waves in underwater acoustic sensor networks (UASNs) have a much lower bandwidth of up to a few kHz, resulting in a lower achievable data rate. Generally, the sensor nodes have been deployed on the beds of the oceans. So, it is very difficult to recharge or replace them, once the batteries of the sensor nodes are drain off. Hence, achievable data rate and energy efficiency (EE) has to be improved simultaneously in UASNs. In this paper, we have presented different non-orthogonal multiple access techniques to improve data rate and various energy harvesting techniques proposed for UASNs to improve the EE. [ABSTRACT FROM AUTHOR]

Stability study for dolutegravir bulk drug was performed and the degradation products formed were identified by chromatography (HPLC, LCMS) and spectroscopy (ESI-MS, FTIR, 1H and 13C NMR) techniques. Degradation of the drug in acidic and peroxide environment yielded one common major degradant f ((2,4-difluorophenyl) methanamine) with a mass peak at m/z = 182.44. In addition to this, five more minor degradation products (a, b, c, d and e) were formed. The structure interpretation showed that the drug degraded to its synthetic precursor and no extra structures were formed. Hence, it was suggested that drug dolutegravir should be kept away from acidic and oxygen rich conditions. [ABSTRACT FROM AUTHOR]

With the growing power demand, the need for innovative and novel methods to operate large interconnected power systems has increased. This reflects more complexity and therefore less secure than before. Hence, modern power systems are more prone to widespread failures. The device that has enhanced the safe and reliable operation of the network and has contributed to capacity augmentation is Flexible AC Transmission System (FACTS). But this is very expensive and must be suitably sized and located to maximize the overall benefit to the system. The paper aims at determining the optimal location and size of the Static Var Compensator (SVC) by optimizing the multi-objective function formulated by different factors that define the system security, namely, voltage deviation, system overload and real power losses. The multi-objective optimization function has been optimized using a Modified Bacterial Foraging Optimization Algorithm (MBFOA). The results are presented and analyzed for an IEEE-30 bus test system and compared with the popular Genetic Algorithm (GA). [ABSTRACT FROM AUTHOR]

Power system planners have come to rely on FACTS devices to overcome several operational limitations in terms of thermal stability, voltage stability, and other inherent limitations offered by the transmission lines. One important aspect that has always intrigued the power system planners and researches alike is in regard to the location and sizing of FACTS devices. This work aims to address this intriguing question by identifying the optimal location and size of the Static Var Compensator (SVC). The optimal location and size is proposed to be identified by optimizing the multi-objective function, formulated by different factors that define the system security, namely Voltage Deviation, System Overload, and Real Power Losses. The multi-objective optimization function has been optimized using a Modified Bacterial Foraging Optimization Algorithm (MBFOA). The results are presented and analysed for an IEEE 30 bus test system. [ABSTRACT FROM AUTHOR]