Controlling high-harmonic generation from strain engineered monolayer phosphorene

Phosphorene, a well-studied 2D allotrope of phosphorus, features unique properties such as widely tunable bandgap, high carrier mobility, and remarkable intrinsic in-plane anisotropy. Utilizing these structural and electronic properties, we investigate ultrafast electron dynamics and high harmonic generation (HHG) from phosphorene subject to band structure engineering through external strain, based on ab initio time-dependent density-functional theory approach. We show that strong field processes in such systems can be optimized and controlled by biaxial tensile and compressive strain engineering, that results in electronic structure modification. While -10% strain resulted in closing of band gap, 2% strain increased the gap by 22% with respect to 0.9 eV in pristine phosphorene, consequently affecting the high harmonic yield. With reduction of gap, by applying strain from 2% to -10%, the valence band near $\Gamma-$point becomes more flat and discreet, resulting in large electronic density of states and enhanced electronic excitation, which reflects in their ultrafast sub-cycle dynamics under laser excitation. Moreover, due to its intrinsic in-plane anisotropy, harmonic yield with laser polarization along the armchair (AC) direction is found to be higher than that of the zigzag (ZZ) direction for all the strain cases. Nearly, an order of magnitude enhancement of harmonic intensity is achieved for -10% strain along AC direction. The current study expands the research possibilities of phosphorene into a previously unexplored domain, indicating its potential for future utilization in extreme-ultraviolet and attosecond nanophotonics, and also for efficient table-top HHG sources.Comment: 16 pages, 10 figures, 1 tabl

Control Strategy for Three Phase Shunt Active Power Filter with Minimum Current Measurements

The active power filter has been proved to be an effective method to mitigate harmonic currents generated by nonlinear loads as well as to compensate reactive power. The methods of harmonic current detection play a crucial part in the performance of active power filter (APF). This paper presents a new control strategy in which three Shunt Active Power filter Configurations aredeveloped in order to define new simple control algorithm which  requires minimum number of current measurements. The effecticeveness of the proposed control strategies are demonstrated through results. The entire control system is implemented with MATLAB/SIMULINK. The simulation results are presented for different control strategies and comparison is made among themDOI:http://dx.doi.org/10.11591/ijece.v1i1.2

Tunable ultrafast thermionic emission from femtosecond-laser hot spot on a metal surface: role of laser polarization and angle of incidence

Ultrafast laser induced thermionic emission from metal surfaces has several applications. Here, we investigate the role of laser polarization and angle of incidence on the ultrafast thermionic emission process from laser driven gold coated glass surface. The spatio-temporal evolution of electron and lattice temperatures are obtained using an improved three-dimensional (3D) two-temperature model (TTM) which takes into account the 3D laser pulse profile focused obliquely onto the surface. The associated thermionic emission features are described through modified Richardson-Dushman equation, including dynamic space charge effects and are included self-consistently in our numerical approach. We show that temperature dependent reflectivity influences laser energy absorption. The resulting peak electron temperature on the metal surface monotonically increases with angle of incidence for P polarization, while for S polarization it shows opposite trend. We observe that thermionic emission duration shows strong dependence on angle of incidence and contrasting polarization dependent behaviour. The duration of thermionic current shows strong correlation to the intrinsic electron-lattice thermalization time, in a fluence regime well below the damage threshold of gold. The observations and insights have important consequences in designing ultrafast thermionic emitters based on a metal based architecture.Comment: 17 pages, 7 figures, 1 tabl

Therapeutic Potential of Dietary Phenolic Acids

Although modern lifestyle has eased the quality of human life, this lifestyle’s related patterns have imparted negative effects on health to acquire multiple diseases. Many synthetic drugs are invented during the last millennium but most if not all of them possess several side effects and proved to be costly. Convincing evidences have established the premise that the phytotherapeutic potential of natural compounds and need of search for novel drugs from natural sources are of high priority. Phenolic acids (PAs) are a class of secondary metabolites spread throughout the plant kingdom and generally involved in plethora of cellular processes involved in plant growth and reproduction and also produced as defense mechanism to sustain various environmental stresses. Extensive research on PAs strongly suggests that consumption of these compounds hold promise to offer protection against various ailments in humans. This paper focuses on the naturally derived PAs and summarizes the action mechanisms of these compounds during disease conditions. Based on the available information in the literature, it is suggested that use of PAs as drugs is very promising; however more research and clinical trials are necessary before these bioactive molecules can be made for treatment. Finally this review provides greater awareness of the promise that natural PAs hold for use in the disease prevention and therapy

Superior Photo-thermionic electron Emission from Illuminated Phosphorene Surface

This work demonstrates that black phosphorene, a two dimensional allotrope of phosphorus, has the potential to be an efficient photo-thermionic emitter. To investigate and understand the novel aspects we use a combined approach in which ab initio quantum simulation tools are utilized along with semiclassical description for the emission process. First by using density functional theory based formalism, we study the band structure of phosphorene. From the locations of electronic bands, and band edges, we estimate the Fermi level and work function. This leads us to define a valid material specific parameter space and establish a formalism for estimating thermionic electron emission current from phosphorene. Finally we demonstrate how the emission current can be enhanced substantially under the effect of photon irradiation. We observe that photoemission flux to strongly dominate over its coexisting counterpart thermionic emission flux. Anisotropy in phosphorene structure plays important role in enhancing the flux. The approach which is valid over a much wider range of parameters is successfully tested against recently performed experiments in a different context. The results open up a new possibility for application of phosphorene based thermionic and photo-thermionic energy converters

ANTIPYRETIC ACTIVITY OF ANNONA PLANTS LEAVES ON BREWER'S YEAST INDUCED FEBRILE RATS

Objective: To evaluate and compare the in vivo antipyretic activity of the methanolic extracts of selected three Annona plant leaves.Methods: The acute oral toxicity determined by OECD class method and the in vivo antipyretic activity was determined by brewer's yeast inducedpyrexia method.Results: The results showed that the methanolic extract of leaves of Annona plants are non-toxic and possessed significant antipyretic effect whichmay be attributed to the presence of flavonoids and saponins in the extracts.Conclusion: This study provides evidences for the antipyretic activity of Annona squamosa, Annona reticulata and Annona muricata possess antipyreticactivity at the tested doses 100 and 200 mg/kg body weight without any side effects, which could partly contribute to its ethno medical use.Keywords: Annona squamosa L, Annona reticulata L, Annona muricata L, Antipyretic activity, Brewer's yeast

Intensity and Resolution Enhancement of Local Regions for Object Detection and Tracking in Wide Area Surveillance

Object tracking in wide area motion imagery is a complex problem that consists of object detection and target tracking over time. This challenge can be solved by human analysts who naturally have the ability to keep track of an object in a scene. A computer vision solution for object tracking has the potential to be a much faster and efficient solution. However, a computer vision solution faces certain challenges that do not affect a human analyst. To overcome these challenges, a tracking process is proposed that is inspired by the known advantages of a human analyst. First, the focus of a human analyst is emulated by doing processing only the local object search area. Second, it is proposed that an intensity enhancement process should be done on the local area to allow features to be detected in poor lighting conditions. This simulates the ability of the human eye to discern objects in complex lighting conditions. Third, it is proposed that the spatial resolution of the local search area is increased to extract better features and provide more accurate feature matching. A quantitative evaluation is performed to show tracking improvement using the proposed method. The three databases, each grayscale sequences that were obtained from aircrafts, used for these evaluations include the Columbus Large Image Format database, the Large Area Image Recorder database, and the Sussex database

Increased yield of smear positive pulmonary TB cases by screening patients with >2 weeks cough, compared to >3 weeks and adequacy of 2 sputum smear examinations for diagnosis

Background RNTCP recommends examining three sputum smears for AFB from Chest Symptomatics (CSs) with cough of >3 weeks for diagnosis of Pulmonary TB (PTB). A previous multi-centric study from Tuberculosis Research centre (TRC) has shown that the yield of sputum positive cases can be increased if duration of cough for screening was reduced to >2 weeks. Other studies have shown that two smear examinations are adequate for diagnosis of smear positive PTB . To validate the above findings, a cross sectional multi-centric study was repeated in different settings in five geographical areas in India. Methods Three primary and secondary level health facilities with high out-patient attendance were selected from two Tuberculosis Units (TU) in each of the 15 selected districts to screen about 10,000 new adult outpatients from each state. For patients who did not volunteer history of cough, symptoms were elicited using a structured simple questionnaire. All the CSs were referred for sputum examination. Results A total of 96,787 out-patients were registered. Among them 69,209 (72%) were new adult out-patients. Using >2 weeks of cough instead of > 3 weeks as the criterion for screening, there was an overall increase of 58% in CS and 23% increase in the detection of smear-positive cases. Among 211 patients, 210 were positive at least by one smear from the initial two specimens. Increase in the work-load if 2 smears were done for patients with cough of >2 weeks cough were 2 specimens (i.e.13 to 15) per day for an adult OPD of 150. Conclusion The yield of sputum positive PTB cases can be improved by screening patients with >2 weeks cough and two specimens are adequate for diagnosis