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Hydrophilic swellable polymers can be well used for the fabrication of matrix formulations. The present investigation aimed to develop controlled release matrix formulations of Amoxicillin trihydrate with different concentration of gum karaya, without changing the other factors. The matrix granules, prepared by wet granulation process were first evaluated for different micrometrics properties like bulk density, tapped density, Hausner’s ratio, Carr’s index. The drug content and swelling behavior were also investigated in granular form. After that the matrix granules were encapsulated in empty gelatin shell. The encapsulated granules of Amoxycillin trihydrate were subjected to dissolution studies. The drug release data were analyzed to interpret the drug release kinetics. The drug release data was fitted in kinetic models of zero order, first order, Higuchi and Korsmeyer-Peppas equation. For the formulations with higher concentration of gum karaya, the cumulative percent of drug released versus time plot exhibits curvilinear nature, which suggests that drug release is not dominated by zero order kinetics. The results showed that drug release is much more acquainted with Korsmeyer–Peppas and Higuchi models. The granules with 10-15% of gum karaya reveal the dominance of the highly swollen layer which controls the drug release from the matrix granules.

We demonstrate that β-oxo-substitution provides effective fine-tuning of both steady-state and transient electronic properties of octaalkyl-β-mono-oxochlorin and all isomers of the β,β′-dioxo-substituted chromophores. The addition of a carbonyl group increases the Qy oscillator strength and red-shifts the absorption spectra. Each oxo-substitution results in a 2-fold increase in the singlet to triplet state intersystem crossing (ISC) rates, resulting in a 4-fold ISC rate increase for the dioxo-substituted chromophores. The effects of oxo-substitution on the ISC rate are thus additive. The progressive increase in the ISC rates correlates directly with the spin–vibronic channels provided by the C═O out-of-plane distortion modes, as evidenced by density functional theory (DFT) modeling. The triplet states, however, were not evenly affected by β-oxo-substitution, and reduction in the triplet lifetime seems to be influenced instead by the presence of NH tautomers in the dioxoisobacteriochlorins.

It is well-known that treatment of β-octaethylporphyrin with H2 O2 /conc. H2 SO4 converts it to a β-oxochlorin as well as all five constitutional isomers of the corresponding β,β'-dioxo-derivatives: two bacteriochlorin-type isomers (β-oxo groups at opposite pyrrolic building blocks) and three isobacteriochlorin-type isomers (β-oxo-groups at adjacent pyrrolic building blocks). By virtue of the presence of the strongly electronically coupled β-oxo auxochromes, none of the chromophores are archetypical chlorins, bacteriochlorins, or isobacteriochlorins. Here the authors present, inter alia, the single crystal X-ray structures of all free-base diketone isomers and a comparative description of their UV-vis absorption spectra in neutral and acidic solutions, and fluorescence emission and singlet oxygen photosensitization properties, Magnetic Circular Dichroism (MCD) spectra, and singlet excited state lifetimes. DFT computations uncover underlying tautomeric equilibria and electronic interactions controlling their electronic properties, adding to the understanding of porphyrinoids carrying β-oxo functionalities. This comparative study lays the basis for their further study and utilization.

The effects of shape, size, and surface plasmon resonance (SPR) peak position (λSPR) on nonlinear absorption (NLA) were investigated at 808 nm, using a femtosecond laser. We found that NLA behavior...

In this contribution, using microwave heating of polyethylene glycol (PEG 200), we have prepared carbon nanodot (CND). It is found that in aqueous medium as well as in the micellar solutions of triblock copolymer, P123 and in anionic surface active ionic liquid (SAIL), 1-butyl-3-methylimidazolium n-octylsulfate ([C4mim][C8SO4]) the fluorescence intensity of CND gets quenched in the presence of cationic cyanine dye HITCP and cationic phenoxazine dye Nile blue (NB). Stern-Volmer constant indicates that the quenching of fluorescence intensity is more in the aqueous medium compared to P123 and [C4mim][C8SO4] i.e., (BmimOs) micelles. Time-correlated single photon counting (TCSPC) measurement reveals that the fluorescence quenching is static in nature and the quenching through Forster resonance energy transfer (FRET) process is not dominant here. Addition of both the cationic dye molecules (HITCP and NB) in CND solution generates new excited state absorption peaks in transient absorption measurement. This observation suggests that a transient species is generated through photoinduced electron transfer (PET) between the donor-acceptor pairs and this PET is responsible for the fluorescence quenching of CNDs by the dye molecules. Moreover, this electron transfer kinetics is relatively faster in bulk water compared to that inside P123 and BmimOs micelle due to the intervention of the surfactant molecules between CND and the dye molecules. Therefore, this study provides a new insight about the PET dynamics between CND and fluorescent dye molecules.

Pressure reconstruction from velocity measurements using particle image velocimetry (PIV) and particle tracking velocimetry (PTV) has drawn significant attention as it can provide instantaneous pressure fields without altering the flow. Previous studies have found that the accuracy of the calcualted pressure field depends on several factors including the accuarcy of the velocity measurement, the spatiotemporal resolutions, the method for calculating pressure-gradient, the algorithm for pressure-gradient integration, the pressure boundary condition, etc. Therefore, it is critical and challenging to quantify the uncertainty of the reconstructed pressure field. The recent development of the uncertainty quantification algorithms for PIV and PTV allows for the local and instantaneous uncertainty estimation of velocity measurement, which can be used to infer the pressure uncertainty. In this study, we introduce a framework that propagates the standard velocity uncertainty defined as the standard deviation of the velocity error distribution through the pressure reconstruction process to obtain the uncertainty of the pressure field. The uncertainty propagations through the calculation of the pressure-gradient and the pressure-gradient integration were modeled as linear transformations, which can reproduce the effects of the spatiotemporal resolutions, the numerical schemes, the integration algorithms, and the pressure boundary condition on the accuracy of the resulting pressure fields. The proposed uncertainty estimation approach also considers the effect of the spatiotemporal and componentwise correlation of the velocity errors in common PIV/PTV measurements on the pressure uncertainty.

Ultrasound Particle image velocimetry (UPIV) is a non-invasive flow measurement technique where acousticopaque flow tracers are injected into a working fluid and ensonified to create ultrasound images. These images are processed using PIV cross-correlation based algorithms to measure the velocity field (Kim et al., 2004). UPIV is useful for opaque flows, primarily where complex flows exist, accordingly, it is used in many industrial and clinical research applications such as studying intracardiac flow (Crase et al., 2007). Furthermore, the measurement provides suitable temporal and spatial resolutions for improved diagnostic metrics. Mentioned applications and the sensitive diagnostic industrial and clinical decisions made based on these measurements intensifies the importance of characterizing the UPIV measurement accuracy and associated uncertainty. However, quantifying UPIV measurement uncertainty is non-trivial due to the complexity of possible uncertainty sources, their combination, and propagation through the measurement chain. The formation of a particle image by ultrasound significantly differs from optical imaging, introducing unique aspects to image quality that must be considered. Particle images are formed across several ultrasound scan lines, yielding an elliptical particle image shape. Furthermore, the particle’s reflected pressure wave is converted to a digital signal that undergoes signal modulation, and this process forms a non-Gaussian point spread function (PSF) along the scan line direction. Additionally, clusters of tracers produce a single, bright image intensity and speckle image pattern. Compared to conventional PIV images, UPIV incurs significantly higher image noise due to lack of filtration for the ultrasound reflection of the non-tracer obstacles.

We present a novel approach to estimate the uncertainty in ensemble particle image velocimetry (PIV) measurements. Ensemble PIV is widely used when the cross-correlation signal-to-noise ratio (SNR) is insufficient to perform a reliable instantaneous velocity measurement. Despite the utility of ensemble PIV, uncertainty quantification for this type of measurement has not been studied. The existing uncertainty quantification algorithms for PIV are developed and used only for instantaneous PIV measurement and do not account for the improved SNR in ensemble PIV. Existing instantaneous uncertainty quantification methods can be divided into direct and indirect categories. Indirect methods require calibration based on the effect of various image parameters (such as noise, particle size, density, velocity gradient, etc.) on the correlation SNR. Indirect methods have not been calibrated for error sources relevant in an Ensemble PIV measurement. Also, they have lower sensitivity to the error sources compared to direct approaches. Direct methods, such as the moment of correlation (MC) and Image Matching (IM), find the uncertainty based on the images and correlation planes without any calibration and are more reliable (Bhattacharya et al., 2018; Sciacchitano et al., 2013). Ensemble PIV is based on ensemble correlations; therefore, MC, which uses the generalized cross-correlation (GCC) plane as a measure of uncertainty, is the most suitable method to be modified to be applicable for the ensemble PIV. The GCC plane is the inverse Fourier transform of the phase correlation and represents the probability density function (PDF) of particles’ displacements (Bhattacharya et al., 2018; Eckstein and Vlachos, 2009). We replaced instantaneous GCC with ensemble GCC and modified MC’s normalization factor to account for the number of ensembles. The MC’s primary limitation is that it assumes a Gaussian shape for the PDF of displacements and estimate the standard deviation of the underlying PDF using a fitted Gaussian. However, the PDF deviates from Gaussian distribution due to velocity gradient or non-Gaussian random displacements. Therefore, MC’s reliability and applicability are reduced for flow fields with non-Gaussian PDFs. Also, our analysis shows that ensemble MC consistently underestimates the uncertainty. So, a generalized and reliable method for uncertainty quantification for ensemble PIV is needed.

Non-invasive flow velocity measurement techniques like volumetric Particle Image Velocimetry (PIV) (Elsinga et al., 2006; Adrian and Westerweel, 2011) and Particle Tracking Velocimetry (PTV) (Maas, Gruen and Papantoniou, 1993) use multi-camera projections of tracer particle motion to resolve three-dimensional flow structures. A key step in the measurement chain involves reconstructing the 3D intensity field (PIV) or particle positions (PTV) given the projected images and known camera correspondence. Due to limited number of camera-views the projected particle images are non-unique making the inverse problem of volumetric reconstruction underdetermined. Moreover, higher particle concentration (>0.05 ppp) increases erroneous reconstructions or “ghost” particles and decreases reconstruction accuracy. Current reconstruction methods either use voxel-based representation for intensity reconstruction (e.g. MART (Elsinga et al., 2006)) or a particle-based approach (e.g. IPR (Wieneke, 2013)) for 3D position estimation. The former method is computationally intensive and has a lesser positional accuracy due to stretched shape of the reconstructed particle along the line of sight. The latter compromises triangulation accuracy (Maas, Gruen and Papantoniou, 1993) due to overlapping particle images for higher particle concentrations. Thus, each method has its own challenges and the error in 3D reconstruction significantly affects the accuracy of the velocity measurement. Though, other methods like maximum-a-posteriori (MAP) estimation have been previously developed (Levitan and Herman, 1987; Bouman and Sauer, 1996) for computed Tomography data, it has not been explored for PIV/ PTV 3D reconstruction. Here, we use a MAP estimation framework to model and solve the inverse problem. The cost function is optimized using a stochastic gradient ascent (SGA) algorithm. Such an optimization can converge to a better local maximum and also use smaller image patches for efficient iterations.

Three-dimensional Particle Tracking Velocimetry (3D-PTV) is a non-invasive flow measurement technique that computes the velocity field by reconstructing 3D particle positions of individual tracer particles and by subsequently tracking those positions. The particle velocity measurement accuracy depends on the faithful reconstruction of 3D particle positions. The complex measurement chain in 3D-PTV involves several steps, from calibration to 3D position reconstruction and particle position tracking, each having its own source of error. Additionally, higher seeding density increases the uncertainty in particle reconstruction and tracking, which in turn, increases the noise in the estimated tracks. A noisy track decreases the measurement accuracy and amplifies any noise in the PTV-derived quantities of interest, which includes acceleration, pressure and vorticity. Thus, track filtering techniques are critical in a 3D-PTV measurement. Track fitting using polynomial functions, filtering methods adopted from signal processing and object tracking are among the well-established techniques used to achieve smooth position, velocity estimates from reconstructed particle trajectories. The Kalman filter is one such filtering technique that is widely used in various applications. The strength of the Kalman filter lies in its ability to perform noise reduction that is informed by existing physical models and the uncertainty estimates of recorded measurements. However, the measurement uncertainty input to the Kalman filter needs to be known at priori, which in many cases may not be available or could be difficult to estimate. In the literature on Kalman filters and their variants applied to 2D-PIV/PTV, the position uncertainty data fed to the filter is either user-defined or estimated based on global noise levels in the PTV measurements. But instantaneous position and velocity uncertainty quantification for individual particle positions/tracks has been challenging in the 3D PTV community. Recent work by Bhattacharya and Vlachos (2020) provides an estimate of the uncertainty in the reconstructed particle positions for a 3D PTV measurement. This position uncertainty estimate dynamically updates the filter gain for each track and enables the evaluation of the performance of the Kalman filter in 3D PTV track filtering.

This work models the effects of gravitational lensing, Doppler boosting, and ellipsoidal variations on eccentric eclipsing binary-system light curves. This is accomplished using a Newtonian orbital-motion code that simulates the orbital velocities and separation of the binary components as a function of time. Improving on previous literature, we examine the effects of orbital eccentricity and period, as well as stellar limb darkening on the expected light curves. Whether lensing, Doppler boosting, or ellipsoidal variation is dominant in the light curves is a function of the separation between the binary components; thus, the combination of all three effects allows for a unique mass-determination method that greatly expands the parameter space for the discovery of compact objects. This suggests the exciting possibility of revealing a large population of nonaccreting compact objects in galactic binary systems. At the same time, the model can be used on systems exhibiting any subset of these effects. In a case study, we fit our model to optical data from the ellipsoidal variable binary system Cygnus X-1, and we compare our determinations with those previously found by different modeling techniques.

Excitonic resonance and binding energies can be altered by controlling the environmental screening of the attractive Coulomb potential. Although this screening response is often assumed to be static, the time evolution of the excitonic quasiparticles manifests a frequency-dependence in its Coulomb screening efficacy. In this letter, we investigate a ground (1s) and first excited exciton state (2s) in a multi-layered transition metal dichalcogenide (MoS$_2$) upon ultrafast photo-excitation. We explore the dynamic screening effects on the latter and show its resonance frequency is the relevant frequency at which screening from the smaller-sized 1s counterparts is effective. Our finding sheds light on new avenues of external tuning on excitonic properties., 6 pages, 3 figures

Piper capense belongs to Piperaceae family and has long been used as a traditional medicine to treat various diseases in several parts of Africa. The present study aims to investigate the effect of Piper capense fruit extract (PCFE) alone and in combination with dacarbazine on metastatic melanoma cell line B16-F10 and in vivo in C57BL/6J mice. Cytotoxic effects of PCFE alone and in association with dacarbazine on B16-F10 cells were studied by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay and colony formation assay. Wound healing assay, immunofluorescence staining, and western blot analysis were performed to evaluate the individual and combined effect of PCFE and dacarbazine on epithelial-mesenchymal transition (EMT). For in vivo studies, C57BL/6J mice were subcutaneously injected with B16-F10 cells (5 × 105 cells/mL), and the effect of PCFE and dacarbazine was studied on tumor development. The alteration of EMT was evaluated by targeting E-cadherin, vimentin, and CD133 in PCFE alone and in combination with dacarbazine-treated tumor tissues by western blot analysis. Phytochemical screening of PCFE reveals the presence of certain secondary metabolites. Our results showed that PCFE alone and in association with dacarbazine has a good activity in preventing B16-F10 melanoma cell progression and clonogenicity. This extract also regulated EMT. In vivo results showed that PCFE (100 mg/kg body weight) reduced tumor size in C57BL/6J mice along with the decrease in the expression of vasculogenic mimicry (VM) tubes as well as an improvement in the qualitative and quantitative expression of markers involved in EMT. Our study suggests that PCFE may be useful for managing the growth and metastasis of melanoma.

ObjectivesTo show simultaneous quantification of flow and mechanics of cardiac function from fetal and neonatal echocardiograms using an integrated set of automated, physics-based, echocardiography analysis methods. BackgroundQuantifying ventricular biomechanics from fetal and neonatal echocardiograms presents unique and significant challenges. Existing analysis tools are designed for adults and cannot accurately assess fetal subjects. MethodsWe used in-house developed analysis algorithms to quantify ventricular biomechanics from four-chamber B-mode and color Doppler routine examinations recordings for three hypoplastic left heart (HLHS) patients at 33-weeks gestation and first week post-birth along with age-matched controls. Chamber morphology, tissue motion, atrioventricular valve inflow, global longitudinal strain, and hemodynamic flow parameters were measured. ResultsPrenatal cardiac output differed between control (LV:157 {+/-} 139 mL/min, RV:257 {+/-} 218 mL/min) and HLHS subjects (410 {+/-} 128 mL/min). This difference persisted for control (LV:233 {+/-} 74 mL/min, RV:242 {+/-} 140 mL/min) and HLHS subjects (637 {+/-} 298 mL/min) after birth. Peak global longitudinal strain measurements did not differ in utero between control (LV: 12.2 {+/-} 4.1%, RV:12.1 {+/-} 4.9%) and HLHS subjects (RV:12.7{+/-} 4.2%). After birth, myocardial contraction increased for the control (LV:15.4 {+/-} 2.8%, RV:22.9 {+/-} 6.9%) and HLHS subjects (14.4 {+/-} 6.2%). Postnatal early filling mitral flow velocity for the control subjects (LV:58.8 {+/-} 17.6 cm/s) and early-filling tricuspid flow of the HLHS subjects (64.8 {+/-} 23.7cm/s) were similar, while the late filling velocity decreased for the control subject LV (33.5 {+/-} 8.1 cm/s) compared to the HLHS subjects (66.9 {+/-} 23.0 cm/s). Importantly, flow energy loss in the fetal HLHS hearts was increased (0.35 {+/-} 0.19 m3/s2) compared to the control subjects (LV:0.09 {+/-} 0.07 m3/s2, RV:0.17 {+/-} 0.12 m3/s2), and further increased postnatally for the HLHS subjects (0.55 {+/-} 0.24 m3/s2) compared to the control subjects (LV:0.23 {+/-} 0.20 m3/s2, RV:0.09 {+/-} 0.06 m3/s2). ConclusionsWe demonstrate the feasibility of integrated quantitative measurements of fetal and neonatal ventricular hemodynamics and biomechanics using only four-chamber B-mode and color Doppler recordings. Short AbstractWe integrated novel echocardiogram analysis methods to quantify ventricular flow and mechanics using apical long-axis B-mode and color Doppler imaging from fetal and neonatal subjects. Three hypoplastic left heart patients (HLHS) imaged at 33-weeks gestation and again in the first postnatal week, along with age-matched controls, were evaluated. For the first time, we show quantified hemodynamics from fetal echocardiography using flow reconstruction, flow energy loss, and intraventricular pressure, as well as global strain and strain rate. These tools are capable of longitudinal analysis of ventricle maturation, flow dynamics, and quantified measurements from routine examinations of complex congenital heart disease.

We introduce the first comprehensive approach to determine the uncertainty in volumetric Particle Tracking Velocimetry (PTV) measurements. Volumetric PTV is a state-of-the-art non-invasive flow measurement technique, which measures the velocity field by recording successive snapshots of the tracer particle motion using a multi-camera set-up. The measurement chain involves reconstructing the three-dimensional particle positions by a triangulation process using the calibrated camera mapping functions. The non-linear combination of the elemental error sources during the iterative self-calibration correction and particle reconstruction steps increases the complexity of the task. Here, we first estimate the uncertainty in the particle image location, which we model as a combination of the particle position estimation uncertainty and the reprojection error uncertainty. The latter is obtained by a gaussian fit to the histogram of disparity estimates within a sub-volume. Next, we determine the uncertainty in the camera calibration coefficients. As a final step, the previous two uncertainties are combined using an uncertainty propagation through the volumetric reconstruction process. The uncertainty in the velocity vector is directly obtained as a function of the reconstructed particle position uncertainty. The framework is tested with synthetic vortex ring images. The results show good agreement between the predicted and the expected RMS uncertainty values. The prediction is consistent for seeding densities tested in the range of 0.01–0.1 particles per pixel. Finally, the methodology is also successfully validated for an experimental test case of laminar pipe flow velocity profile measurement where the predicted uncertainty in the streamwise component is within 9% of the RMS error value.

The increasing demand for lightweight materials in various engineering and structural applications led to the introduction of aluminum matrix composites (AMC). In this work, a novel zircon sand (ZrSiO4)-reinforced aluminum (grade-LM25) matrix composites were produced using stir casting method, and experimental investigation on machinability based on 18 orthogonal array of mixed level design is carried out formulated by Taguchi. Machining conditions (Dry/MQL), cutting speed (CS), depth of cut (DoC), feed rate (FR) and zircon sand reinforcement are varied in the experiments, and output responses like resultant cutting force (Fr), surface roughness (Ra) and tool wear (TW) were measured. Fuzzy logic (FL), a soft computing technique coupled with one of a multi-objective optimization technique, grey relational analysis (GRA) is implemented to find the optimal cutting parameters. The significant factors are analyzed using ANOVA. The optimum machining levels obtained are MQL cutting environment with a cutting speed of 200 m/min, feed rate of 0.06 mm/rev, depth of cut of 1 mm and 10% zircon sand particle reinforcement.

A novel pressure reconstruction method is proposed to use the uncertainty information to improve the instantaneous pressure fields from velocity fields measured using particle image velocimetry (PIV) or particle tracking velocimetry (PTV). First, the pressure gradient fields are calculated from velocity fields, while the local and instantaneous pressure gradient uncertainty is estimated from the velocity uncertainty using a linear-transformation-based algorithm. The pressure field is then reconstructed by solving an overdetermined linear system which involves the pressure gradients and boundary conditions. This linear system is solved with generalized least squares (GLS) which incorporates the previously estimated variances and covariances of the pressure gradient errors as inverse weights to optimize the reconstructed pressure field. The method was validated with synthetic velocity fields of a 2D pulsatile flow, and the results show significantly improved pressure accuracy. The pressure error reduction by GLS was 50% with 9.6% velocity errors and 250% with 32.1% velocity errors compared to the existing baseline method of solving the pressure Poisson equation (PPE). The GLS was more robust to the velocity errors and provides greater improvement with spatially correlated velocity errors. For experimental validation, the volumetric pressure fields were evaluated from the velocity fields measured using 3D PTV of a laminar pipe flow with a Reynolds number of 630 and a transitional pipe flow with a Reynolds number of 3447. The GLS reduced the median absolute pressure errors by as much as 96% for the laminar pipe flow compared to PPE. The mean pressure drop along the pipe predicted by GLS was in good agreement with the empirical estimation using Darcy–Weisbach equation for the transitional pipe flow.

In this work, we depleted glutathione (GSH) by releasing SO2 with internal stimulus GSH itself, and also selectively marked the cancer cells followed by release of anticancer drug using another orthogonal stimulus i.e., two-photon (TP) NIR light by a single naphthalene based chromophore (TP absorbance 77 GM and uncaging cross-section 21 GM). We demonstrated the improved therapeutic efficacy of chlorambucil by the stepwise dual stimuli approach and dual surveillance of both the drug uncaging process in real-time using in vitro studies.

In spite of achieving high power conversion efficiency (PCE), organo-halide perovskites suffer from long term stability issues. Especially the grain boundaries of polycrystalline perovskite films are considered as giant trapping sites for photo-generated carriers and therefore play an important role in charge transportation dynamics. Surface engineering via grain boundary modification is the most promising way to resolve this issue. A unique antisolvent-cum-quantum dot (QD) assisted grain boundary modification approach has been employed for creating monolithically grained, pin-hole free perovskite films, wherein the choice of all-inorganic CsPbBrxI3−x (x = 1–2) QDs is significant. The grain boundary filling by QDs facilitates the formation of compact films with 1–2 μm perovskite grains as compared to 300–500 nm grains in the unmodified films. The solar cells fabricated by CsPbBr1.5I1.5 QD modification yield a PCE of ∼16.5% as compared to ∼13% for the unmodified devices. X-ray photoelectron spectral analyses reveal that the sharing of electrons between the PbI6− framework in the bulk perovskite and Br− ions in CsPbBr1.5I1.5 QDs facilitates the charge transfer process while femtosecond transient absorption spectroscopy (fs-TAS) suggests quicker trap filling and enhanced charge carrier recombination lifetime. Considerable ambient stability up to ∼720 h with

The X-ray binary pulsar XTE J1829-098 has been observed at extremely low luminosities for its spin period of 7.8448 s. Although its distance is uncertain by a factor of 4, the lowest observed X-ray fluxes may not correspond to its minimal-accretion propeller state or to nonaccreting states occurring at even lower X-ray luminosities, in which case the source has been caught at the bottom of the Corbet gap. We analyze all proposed distances D to the binary and the lowest X-ray fluxes, and we find only two physically acceptable solutions: (a) For D = 4.5 kpc (if the companion is a main-sequence B0 star), the neutron star is canonical with mass 1.41 M ⊙, radius 10.1 km, and a purely dipolar magnetic field as indicated by a cyclotron absorption line detected at 15 keV. In this case, the source has been observed at the bottom of the Corbet gap, the third high-mass X-ray binary pulsar to be caught in this state after the “twins” 4U 0115+63 and V 0332+53 found by Tsygankov et al. (b) For D = 18 kpc (if the companion is a B0.5Ib supergiant), the neutron star is ultramassive with mass 2.62 M ⊙, radius 18.7 km, and a dominant nondipolar magnetic field B mul = 1.26 TG (versus a dipolar component of only B dip = 0.43 TG). In this case, the source has been observed in its propeller state.

This work examines the recent X-ray observations of the active galactic nucleus KIC 11606854 (nicknamed “Spikey”) by the Chandra space telescope. Based on previous observations of a symmetric flare in the system’s light curve by the Kepler space telescope, Spikey has been proposed to be a self-lensing supermassive black hole binary system in which the more massive black hole gravitationally lenses the accretion flow of its smaller companion. The recent Chandra observations (2020 March–May) correspond to the time when the next pulse was expected to occur and were separated in enough time to observe the apparent relativistic Doppler boosting effect from the high orbital velocities of the black holes. We model the expected self-lensing plus Doppler boosting light curve using our wavelength-dependent extended source self-lensing model combined with our relativistic orbital motion code. This orbital motion code is capable of modeling the expected apsidal precession for Spikey, which can be used to predict future pulses. We show that the expected signal was undetectable in the Chandra data as the intrinsic X-ray variability associated with the system was large relative to the changes expected by self-lensing and Doppler boosting. Expected flux increases in more favorable wavelengths were also calculated using our wavelength-dependent self-lensing model, revealing a relationship between the observing wavelength and measured orbital inclination.

Commercially available polymer films of a particular brand (Desmat CT100), identified as Polyethylene Terephthalate (PET), was shown to be very effective as Nuclear Track Detectors (NTDs) with a very high detection threshold (Z/ β ≈ 140). It makes this particular brand of PET films an ideal choice as an NTD for rare event (e.g. strangelets) search in cosmic rays as well as in particle accelerators. Charge response and other properties of PET films from different batches of the Desmat CT100 brand as well as PET films from two other manufacturers, Plus Print and Office Plus were studied to check for consistency. Those studies show no significant difference among different batches of PET films for the Desmat CT100 brand. But statistically significant differences in charge response are seen between PET films from different manufacturers despite similarities in their chemical composition.

A unique delay-dependent dynamic switching of optical nonlinearity in terms of saturation absorption (SA) and excited state absorption (ESA) in graphene oxide (GO) and reduced graphene oxide (RGO2 and RGO100) is achieved with an optical pump and white light super-continuum probe only above a threshold pump intensity. Infrared and chemical reduction are used to obtain RGO2 and RGO100 respectively. The switching regime of probe wavelength can be modulated by varying either pump wavelength or degree of reduction. When pumped at 415 nm, the threshold pump intensity to obtain switching property decreases to 9 GW/cm2 for RGO2 from 18 GW/cm2 in GO and the tunability range shifts from 471 to 526 nm for as grown GO to 519–623 nm in maximally reduced RGO2. Though the saturation intensity of intrinsic non-degenerate two photon absorption (nd-TPA) is found to be lower in GO (4.3 GW/cm2) than RGO2 (18.2 GW/cm2), nd-TPA coefficient increases from 0.0015 cm/GW (GO) to 0.0026 cm/GW (RGO2) with increasing reduction. The detailed kinetics of the scattering processes show variation as a function of pump power, probe wavelength and degree of reduction. A model band diagram based on amorphous-carbon model and a Tauc analysis are used to explain the unusual nonlinear optical properties.

Inducements for research participants are considered controversial. Researchers face an ethical dilemma if they offer money as an inducement when enrolling volunteers for their study. Do these payments invalidate the consent process and make this unethical? Should the results of such studies be considered invalid? A recent publication by Persad and colleagues supports differential payment to volunteers, based upon their level of involvement, from an ethical perspective. Our current response to this article explores a few more areas of controversy and attempts to clarify them.

Femtosecond (fs) laser excited second harmonic (SH) and multiphoton absorption (MPA) induced UV luminescence generation behaviour of Zinc oxide (ZnO) nanofibers is reported here. The used nanofibers are grown by seed assisted chemical bath deposition technology over glass substrates and are excited by a near-infrared (NIR) Ti: Sapphire laser emitting pulses of wavelength 812 nm and duration 100 fs. The peak wavelength of SH and MPA induced UV luminescence signals are found to be 406 nm and 398 nm respectively. Due to good optical quality, no defect level related MPA induced visible luminescence is observed in nanofibers. In comparison to this, ZnO nanostructures grown over plane substrate without seed layer shows very less SH and MPA induced UV luminescence. However in this case, the defect level related MPA induced visible luminescence was found to be very high. Applications like ultrafast pulse diagnostics, NIR induced photodynamic therapy etc. require high SH and MPA induced UV luminescence and low defect level related visible luminescence. So the ZnO nanofibers can be a potential candidate for these applications.