Bright Ring Research Articles

The Dark Side of Pluto

Abstract During its departure from Pluto, New Horizons used its LORRI camera to image a portion of Pluto’s southern hemisphere that was in a decades-long seasonal winter darkness, but still very faintly illuminated by sunlight reflected by Charon. Recovery of this faint signal was technically challenging. The bright ring of sunlight forward-scattered by haze in the Plutonian atmosphere encircling the nightside hemisphere was severely overexposed, defeating the standard smeared-charge removal required for LORRI images. Reconstruction of the overexposed portions of the raw images, however, allowed adequate corrections to be accomplished. The small solar elongation of Pluto during the departure phase also generated a complex scattered-sunlight background in the images that was three orders of magnitude stronger than the estimated Charon-light flux (the Charon-light flux is similar to the flux of moonlight on Earth a few days before first quarter). A model background image was constructed for each Pluto image based on principal component analysis applied to an ensemble of scattered-sunlight images taken at identical Sun−spacecraft geometry to the Pluto images. The recovered Charon-light image revealed a high-albedo region in the southern hemisphere. We argue that this may be a regional deposit of N2 or CH4 ice. The Charon-light image also shows that the south polar region currently has markedly lower albedo than the north polar region of Pluto, which may reflect the sublimation of N2 ice or the deposition of haze particulates during the recent southern summer.

PD01-05 PROBING THE BLADDER WALL DIFFUSION OF INSTILLED GADOBUTROL BY MRI

You have accessJournal of UrologyInfections/Inflammation/Cystic Disease of the Genitourinary Tract: Interstitial Cystitis (PD01)1 Sep 2021PD01-05 PROBING THE BLADDER WALL DIFFUSION OF INSTILLED GADOBUTROL BY MRI Pradeep Tyagi, Chan-Hong Moon, Nishant Singh, Marc Connell, Jodi Maranchie, Christopher Chermansky, Naoki Yoshimura, and Jonathan Kaufman Pradeep TyagiPradeep Tyagi More articles by this author , Chan-Hong MoonChan-Hong Moon More articles by this author , Nishant SinghNishant Singh More articles by this author , Marc ConnellMarc Connell More articles by this author , Jodi MaranchieJodi Maranchie More articles by this author , Christopher ChermanskyChristopher Chermansky More articles by this author , Naoki YoshimuraNaoki Yoshimura More articles by this author , and Jonathan KaufmanJonathan Kaufman More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000001965.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Intravesical therapy is critical for bladder cancer and a secondary option for interstitial cystitis and overactive bladder patient's refractory to oral treatment. Although paracellular diffusion of instilled drugs and radioactive agents from urine is suggested by ultrastructural studies and studies on diffusion across the excised whole bladder wall in Ussing chamber, the kinetics of diffusion across just the thickness of bladder mucosa is yet to be probed directly in a radiation-free manner with a non-invasive, non-tissue destructive method. Since MRI is capable of imaging the microscopic dimensions of bladder mucosa (Am J Physiol Renal Physiol 2020;319(3): F506-F514.), we investigated the diffusion kinetics of instilled Gadobutrol in a phantom constructed with 12% polyacrylamide (PLGA) gel, whose nanometer sized pores can partly mimic the nanometer gap of the apico-lateral tight junctions in mammalian urothelium. METHODS: PLGA gel was poured into a plastic jar while embedding 9 glass tubes which were removed upon setting of gel to create 9 cylindrical cavities for instilling ascending concentrations [0.5-20 mM] of Gadobutrol together with a fixed concentration of Ferumoxytol 0.1 mM. Phantom was wrapped by a 4 channel-flexible receiver coil for imaging in 3T scanner (Siemens, BioGraph) using T2 weighted Half-Fourier Acquisition Single-shot Turbo spin Echo imaging (HASTE) (repetition time 1000-1300 ms/echo time 80-90 ms). Gel diffusion of Gadobutrol was assessed by imaging at 30 min and at 5 h. RESULTS: The bright ring around the cavities demonstrates that molecular size of 0.8 nm permits easy diffusion of Gadobutrol into the >40 times bigger pores of 12% PLGA gel. The concentration gradient is the driving force for Gadobutrol diffusion is supported by the dependence of ring brightness on Gadobutrol concentration [0.5-20 mM] at room temperature and on the expansion of dark blob at 5 h in cavities filled with Gadobutrol 5-20 mM to recapitulate the classical pseudolayering effect of Gadobutrol accumulating into stored urine of bladder. CONCLUSIONS: MR imaging validated the linear relationship between Gadobutrol concentration in cavity and the signal gain in the surrounding gel, a surrogate for bladder mucosa. Findings support that MRI at clinical scanner can reliably assess the mucosal diffusion of instilled drugs and probes in bladder permeability assay. Source of Funding: DK 108397;CA252590 © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e32-e32 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Pradeep Tyagi More articles by this author Chan-Hong Moon More articles by this author Nishant Singh More articles by this author Marc Connell More articles by this author Jodi Maranchie More articles by this author Christopher Chermansky More articles by this author Naoki Yoshimura More articles by this author Jonathan Kaufman More articles by this author Expand All Advertisement Loading ...

Photon ring and observational appearance of a hairy black hole

Recently, the image of a Schwarzschild black hole with an accretion disk has been revisited, and it showed that the ``photon ring,'' defined as highly bent light rays that intersect the disk plane more than twice, is extremely narrow and makes a negligible contribution to the total brightness. In this paper, we investigate the observational appearance of an optically and geometrically thin accretion disk around a hairy black hole in an Einstein-Maxwell-scalar model. Intriguingly, we find that in a certain parameter regime, due to an extra maximum or an ``anklelike'' structure in the effective potential for photons, the photon ring can be remarkably wide, thus making a notable contribution to the flux of the observed image. In particular, there appears a wide and bright annulus, which comprises multiple concentric bright thin rings with different luminosity, in the high resolution image.

Dust growth, fragmentation, and self-induced dust traps in phantom

ABSTRACT We present the implementation of a dust growth and fragmentation module in the public smoothed particle hydrodynamics (SPH) code phantom. This module is made available for public use with this paper. The coagulation model considers locally monodisperse dust size distributions around single values that are carried by the SPH particles. Along with the presentation of the model, implementation, and tests, we showcase growth and fragmentation in a few typical circumstellar disc simulations and revisit previous results. The module is also interfaced with the radiative transfer code mcfost, which facilitates the comparison between simulations and ALMA observations by generating synthetic maps. Circumstellar disc simulations with growth and fragmentation reproduce the ‘self-induced dust trap’ mechanism first proposed in 2017, which supports its existence. Synthetic images of discs featuring this mechanism suggest it would be detectable by ALMA as a bright axisymmetric ring at several tens of au from the star. With this paper, our aim is to provide a public tool to be able to study and explore dust growth in a variety of applications related to planet formation.

Polarimetric signatures of the photon ring of a black hole that is pierced by a cosmic axion string

A black hole image contains a bright ring of photons that have closely circled the black hole on their way from the source to the detector. Here, we study the photon ring of a rotating black hole which is pierced by a global hyper-light axion-type cosmic string. We show that the coupling \U0001d719F overset{sim }{F} between the axion \U0001d719 and the photon can give rise to a unique polarimetric structure of the photon ring. The structure emerges due to an Aharonov-Bohm type effect that leads to a change of the polarization directions of linear polarized photons when they circle the black hole. For several parameter choices, we determine concrete polarization patterns in the ring. Measuring these patterns can provide us with a way of determining the value of the coefficient of the mixed anomaly between electromagnetism and the symmetry that gave rise to the cosmic string. Finally, we briefly review a possible formation mechanism of black holes that are pierced by cosmic strings and discuss under which conditions we can expect such objects to be present as supermassive black holes in the center of galaxies.

Influence of quantum correction on black hole shadows, photon rings, and lensing rings * *J.P. is supported by the China Scholarship Council. M.G. is supported by National Natural Science Foundation of China (NSFC) (11947210) and funded by China Postdoctoral Science Foundation (2019M660278). X.H.F. is supported by NSFC (11905157, 11935009)

We calculate photon sphere and critical curve for a quantum corrected Schwarzschild black hole, finding that they violate universal inequalities proved for asymptotically flat black holes that satisfy the null energy condition in the framework of Einstein gravity. This violation seems to be a common phenomenon when considering quantum modification of Einstein gravity. Furthermore, we study the shadows, lensing rings, and photon rings in the quantum corrected Schwarzschild black hole. The violation leads to a larger bright lensing ring in the observational appearance of the thin disk emission near the black hole compared with the classical Schwarzschild black hole. Our analysis may provide observational evidence for the quantum effect of general relativity.

Morphological, magnetic and EPR studies of ZnO nanostructures doped and co-doped with Ni and Sr

Herein, were analyzed the effects of Sr and Ni addition on the morphological, electronic and magnetic properties of ZnO nanoparticles synthesized by the sol gel route. Morphological analysis showed agglomerated particles with nonuniform shapes (polyhedral, hexagonal and spherical) and the average size distributions were calculated counting more than 100 nanoparticles (sizes between 43 and 75 nm). For pure ZnO sample, the selected area electron diffraction (SAED) showed bright and concentric discontinuous diffraction rings, while the co-doped samples, presented patterns well-organized concentric circular rings, typical of reflection of regularly arranged atoms. The electron paramagnetic resonance (EPR) was employed to analyze the intrinsic defects due to the dopant inclusion. In addition, the EPR spectra were simulated using the spin quantum number (S = 1) for Ni2+ to understand the experimental results. Ni ions were used as a local probe in the comparative study by EPR, capturing subtle modifications in the zero-field interactions due to induced strain in the lattice. Microscopically the changes observed, through the EPR study, result from the reduction of the axial distortion of the ligand field and increasing in the distortion perpendicular to the principal axis. Magnetic study showed a typical significant diamagnetism at 300 K, while a paramagnetic contribution was more evident at 4 K. The work contributes to clarify the complex magnetic response in ZnO nanoparticles doped and co-doped with Sr and Ni.

Atomic Carbon in the Central Molecular Zone of the Milky Way: Possible Cosmic-Ray Induced Chemistry or Time-dependent Chemistry Associated with SNR Sagittarius A East

Abstract Atomic carbon (C0), being one of the most abundant atomic/molecular species observed in dense molecular gas, is potentially a good tracer of molecular gas mass in many chemical/physical environments, though the variation in C0 abundance outside the Galactic disk region is not yet fully known. This paper presents a wide-field 500 GHz [C i] map of the Galactic central molecular zone (CMZ) obtained with the ASTE 10 m telescope. Principal component analysis and non-LTE multi-transition analysis have shown that [C i] emission predominantly originates from the low-excitation gas component with a temperature of 20–50 K and density of ∼103 cm−3, whereas C0 abundance is likely suppressed in the high-excitation gas component. The average N(C0)/N(CO) abundance ratio in the CMZ is 0.3–0.4, which is 2–3 times that in the Galactic disk. The N(C0)/N(CO) ratio increases to 0.7 in the innermost 10 pc region and to ∼2 in the circumnuclear disk. We discovered C0-rich regions distributed in a ring shape encircling the supernova remnant (SNR) Sgr A East, indicating that the C0 enrichment in the central 10 pc region is a consequence of a molecular cloud–SNR interaction. In the 15 atoms/molecules included in principal component analysis, CN is the only other species that increases in the [C i]-bright ring. The origin of the [C i]-bright ring is likely a cosmic-ray-dominated region created by low-energy cosmic-ray particles accelerated by Sgr A East or primitive molecular gas collected by the SNR in which the conversion from C0 to CO has not reached equilibrium.

Photon spheres and spherical accretion image of a hairy black hole

In this paper, we first consider null geodesics of a class of charged, spherical and asymptotically flat hairy black holes in an Einstein-Maxwell-scalar theory with a non-minimal coupling for the scalar and electromagnetic fields. Remarkably, we show that there are two unstable circular orbits for a photon in a certain parameter regime, corresponding to two unstable photon spheres of different sizes outside the event horizon. To illustrate the optical appearance of photon spheres, we then consider a simple spherical model of optically thin accretion on the hairy black hole, and obtain the accretion image seen by a distant observer. In the single photon sphere case, only one bright ring appears in the image, and is identified as the edge of the black hole shadow. Whereas in the case with two photon spheres, there can be two concentric bright rings of different radii in the image, and the smaller one serves as the boundary of the shadow, whose radius goes to zero at the critical charge.

A Circumplanetary Disk around PDS70c

Abstract PDS 70 is a unique system in which two protoplanets, PDS 70 b and c, have been discovered within the dust-depleted cavity of their disk, at ∼22 and 34 au, respectively, by direct imaging at infrared wavelengths. Subsequent detection of the planets in the Hα line indicates that they are still accreting material through circumplanetary disks. In this Letter, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the dust continuum emission at 855 μm at high angular resolution (∼20 mas, 2.3 au) that aim to resolve the circumplanetary disks and constrain their dust masses. Our observations confirm the presence of a compact source of emission co-located with PDS 70 c, spatially separated from the circumstellar disk and less extended than ∼1.2 au in radius, a value close to the expected truncation radius of the circumplanetary disk at a third of the Hill radius. The emission around PDS 70 c has a peak intensity of ∼86 ± 16 μJy beam−1, which corresponds to a dust mass of ∼0.031 M ⊕ or ∼0.007 M ⊕, assuming that it is only constituted of 1 μm or 1 mm sized grains, respectively. We also detect extended, low surface brightness continuum emission within the cavity near PDS 70 b. We observe an optically thin inner disk within 18 au of the star with an emission that could result from small micron-sized grains transported from the outer disk through the orbits of b and c. In addition, we find that the outer disk resolves into a narrow and bright ring with a faint inner shoulder.

ALMA 870 μm continuum observations of HD 100546

This paper reports on a new analysis of archival ALMA 870 μm dust continuum observations. Along with the previously observed bright inner ring (r ~ 20–40 au), two addition substructures are evident in the new continuum image: a wide dust gap, r ~ 40–150 au, and a faint outer ring ranging from r ~ 150 au to r ~ 250 au and whose presence was formerly postulated in low-angular-resolution ALMA cycle 0 observations but never before observed. Notably, the dust emission of the outer ring is not homogeneous, and it shows two prominent azimuthal asymmetries that resemble an eccentric ring with eccentricity e = 0.07. The characteristic double-ring dust structure of HD 100546 is likely produced by the interaction of the disk with multiple giant protoplanets. This paper includes new smoothed-particle-hydrodynamic simulations with two giant protoplanets, one inside of the inner dust cavity and one in the dust gap. The simulations qualitatively reproduce the observations, and the final masses and orbital distances of the two planets in the simulations are 3.1 MJ at 15 au and 8.5 MJ at 110 au, respectively. The massive outer protoplanet substantially perturbs the disk surface density distribution and gas dynamics, producing multiple spiral arms both inward and outward of its orbit. This can explain the observed perturbed gas dynamics inward of 100 au as revealed by ALMA observations of CO. Finally, the reduced dust surface density in the ~40–150 au dust gap can nicely clarify the origin of the previously detected H2O gas and ice emission.

In the Trenches of the Solar-stellar Connection. IV. Solar Full-disk Scans of C ii, Si iv, and Mg ii by the Interface Region Imaging Spectrograph

Abstract About once a month, the Interface Region Imaging Spectrograph conducts day-long raster scans of the full Sun in three ultraviolet spectral channels. These full-disk mosaics are valuable in the solar context, but provide a unique connection to the distant, unresolved stars. Here, 10 deep-exposure scans (4–8 s per slit step), collected during the peak and decline of sunspot Cycle 24, were analyzed. Spatial spectra (2″ pixels) of resonance lines of C ii (T ∼ 104 K), Si iv (8 × 104 K), and Mg ii (8 × 103 K) were fitted with a pseudo-Gaussian model to track the emission strengths, widths, and shifts in the various surface features that comprise the quiet Sun and active regions. The full-disk mosaic spectra compare well to tracings of solar-twin α Centauri A (HD 128620; G2 V). The contrast between disk-average spectra from cycles MIN and MAX is relatively modest (∼50% in Si iv), but, remarkably, the brightest solar pixels in active regions, at 2″ resolution, exceed the global-average intensities of the most active Sun-like stars, suggesting a deeper solar-stellar connection. Si iv shows a conspicuous bright ring at the limb, whereas optically thicker C ii and Mg ii are suppressed (more so for the latter). The Si iv emission favors the bright knots of the large-scale supergranulation network, while the cooler Mg ii emission is more ubiquitous and C ii intermediate. The non-Gaussian profile of full-disk C iv, similar in formation temperature to Si iv, was previously interpreted as a combination of narrow and broad dynamical components, but the prevalence of the characteristic line shape in the finest resolution spatial pixels of Si iv here provides support for alternative formation scenarios, for example, invoking κ-distributions.

Global imaging with high resolution region of interest using fusion data based on dual-field of view detection system.

X-ray micro-computed tomography (CT) is an important tool for high-resolution three-dimensional imaging. But one limitation of micro-CT is the compromise between resolution and fields of view (FOV). In this paper, we develop an x-rays dual-FOV optical coupling detection (DFOCD) system for global imaging with high-resolution region of interest (ROI). In DFOCD system, the beam splitter separates lights to form two sub-optical paths, two objectives with different FOV and magnification are used in the two sub-optical paths for dual-FOV imaging. Then a data fusion method is proposed to register and fuse dual-FOV data. Reconstructed images are obtained based on back projection filtering algorithm using fusion data. Dual-FOV data are collected simultaneously in DFOCD system, which precludes artifacts in fusion images from phantom movement or changes in two acquisitions on common micro-CT, and also saves scanning time. Simulation and experimental results show that details in ROI and global morphology of phantoms are correctly reconstructed. Bright ring artifacts of ROI caused by truncated data are corrected in reconstruction images. Therefore, global imaging with high-resolution ROI of samples can be obtained by single scan experiment using DFOCD system and data fusion method, which is expected to expand the application of micro-CT.

Survival of ALMA rings in the absence of pressure maxima

ABSTRACT Recent ALMA observations have revealed that a large fraction of protoplanetary discs contain bright rings at (sub)millimetre wavelengths. Dust trapping induced by pressure maxima in the gas disc is a popular explanation for these rings. However, it is unclear whether such pressure bumps can survive for evolutionary time-scales of the disc. In this work, we investigate an alternative scenario, which involves only dust–gas interactions in a smooth gas disc. We postulate that ALMA rings are a manifestation of a dense, clumpy mid-plane that is actively forming planetesimals. The clumpy medium itself hardly experiences radial drift, but clumps lose mass by disintegration and vertical transport and planetesimal formation. Starting from a seed ring, we numerically solve the transport equations to investigate the ring’s survival. In general, rings move outwards due to diffusion of the clump component. Without pressure support, rings leak material at rates ∼40 ${\rm M}_\oplus \, \mathrm{Myr}^{-1}$ and in order for rings to survive, they must feed from an external mass reservoir of pebbles. In the case where the pebble size is constant in the disc, a cycle between ring formation and dispersion emerges. Rings produce large quantities of planetesimals, which could be material for planet formation and explain the massive budget inferred debris disc. Mock images of ALMA observations compare well to the rings of Elias 24 and AS 209 from DSHARP’s sample.

Postharvest senescent dark spot development mechanism of Musa acuminata ("Khai" banana) peel associated with chlorophyll degradation and stomata cell death.

The occurrence of the postharvest physiological disorder of dark spots on the peel of the ripened "Khai" banana has led to a reduction in its commercial value. The objective of the present study was to investigate the development mechanisms of senescence dark spots of the "Khai" (Musa AA group) banana peel in relation to chlorophyll degradation and stomata cell death. Freshly harvested bananas (commercial mature green stage) were let to ripened at 25±2°C (90%-95% RH). Peel color, senescent spots, DNA degradation, chlorophyll content, chlorophyll-degrading enzyme activities were assessed. The senescent dark spots developed on the ripened bananas right after 6days of storage, which coincided with remarkably increased DNA degradation, and a rapid decreased of hue angle value and total chlorophyll content which indicated the chlorophyll degradation. The activities of chlorophyllase, chlorophyll-degrading peroxidase and pheophytinase increased gradually to the highest point where the chlorophyll content drastically reduced and the appearance of the dark spots was first recorded after 6days of storage. These dark spots were observed to be surrounded with a bright luminescent ring of hypermodified fluorescent chlorophyll catabolites (FCCs), the product of chlorophyll breakdown. Additionally, the scanning electron microscope (SEM) revealed that the dark spots were found to have originated from the collapsed cells around the stomata of the ripened banana peel whereby the chlorophyll was entirely diminished. PRACTICAL APPLICATIONS: This research revealed the senescent dark spot development mechanisms of the "Khai" banana peel. The dark spot development symptom on the banana peel surface was caused by the senescence and cell death of the relevant stomata, further associated with chlorophyll degradation. Therefore, any further research into minimizing the dark spot symptom must focus on preventing or delaying stomata senescence and cell death.

Characterizing the dust content of disk substructures in TW Hydrae

Context. A key piece of information to understand the origin and role of protoplanetary disk substructures is their dust content. In particular, disk substructures associated with gas pressure bumps can work as dust traps, accumulating grains and reaching the necessary conditions to trigger the streaming instability. Aims. In order to shed some light on the origin and role that disk substructures play in planet formation, we aim to characterize the dust content of substructures in the disk of TW Hya. Methods. We present Atacama Large Millimeter Array (ALMA) observations of TW Hya at 3.1 mm with ~50 milliarcsecond resolution. These new data were combined with archival high angular resolution ALMA observations at 0.87, 1.3, and 2.1 mm. We analyze these multiwavelength data to infer a disk radial profile of the dust surface density, maximum particle size, and slope of the particle size distribution. Results. Most previously known annular substructures in the disk of TW Hya are resolved at the four wavelengths. Inside the inner 3 au cavity, the 2.1 and 3.1 mm images show a compact source of free–free emission, likely associated with an ionized jet. Our multiwavelength analysis of the dust emission shows that the maximum particle size in the disk of TW Hya is >1 mm. The inner 20 au are completely optically thick at all four bands, which results in the data tracing different disk heights at different wavelengths. Coupled with the effects of dust settling, this prevents the derivation of accurate density and grain size estimates in these regions. At r > 20 au, we find evidence of the accumulation of large dust particles at the position of the bright rings, indicating that these are working as dust traps. The total dust mass in the disk is between 250 and 330 M⊕, which represents a gas-to-dust mass ratio between 50 and 70. Our mass measurement is a factor of 4.5–5.9 higher than the mass that one would estimate using the typical assumptions of large demographic surveys. Conclusions. Our results indicate that the ring substructures in TW Hya are ideal locations to trigger the streaming instability and form new generations of planetesimals.

Exploding paraxial beams, vortex beams, and cylindrical beams of light with finite power in linear media, and their enhanced longitudinal field

We present a set of paraxial light beams with cylindrical symmetry, smooth and localized transversal profile carrying finite power, that develop intensity singularities when they are focused in a linear medium, such as vacuum. They include beams with orbital angular momentum and with radial polarization, in which case they develop punctual phase and polarization singularities surrounded by infinitely bright rings, along with singular longitudinal fields. In practice, these effects are manifested in focal intensities and spot sizes, vortex bright ring intensities and radii, and strengths of the longitudinal field, that strongly change with the lens aperture radius. Continuous control of these focal properties is thus exercised without changing the light incident on the lens, with substantially the same collected power, and while maintaining paraxial focusing conditions. As solutions of the Schr\"odinger equation, these exploding beams have analogues in other areas of physics where this equation is the fundamental dynamical model.

Dynamic evaluation of an in vivo postinflammatory hyperpigmentation model using reflectance confocal microscopy and spectrophotometry.

Postinflammatory hyperpigmentation (PIH) reflects a dynamic process from primary injury and cutaneous inflammation to subsequent melanogenesis and hyperpigmentation, of which pathogenesis remains unclear, hindering the development of targeted therapies. To observe the dynamic development of PIH; determine the starting point and peak point of the inflammatory phase and pigmentary phase; and clarify the timing of anti-inflammatory and anti-pigmentary treatment. Thirty healthy volunteers with Fitzpatrick skin types III-IV were enrolled and underwent suction blisters. The noninvasive evaluation of inflammation and hyperpigmentation on suction blister sites were performed via spectrophotometry (CM2600d and SIAscope) and RCM for the following 24weeks. We successfully observed suction blister-induced PIH lasting over 24weeks. The inflammatory phase started soon after the procedure and lasted for 8-12weeks, manifested by significantly elevated a* values and erythema index detected by spectrophotometry, as well as inflammatory infiltration and angiogenesis shown in RCM images. Meanwhile, melanogenesis was accelerated after week 3 and reached peak on week 8, manifested by significantly accumulated melanin granules and bright pigment rings in different depths under RCM, which was in parallel with elevated melanin index. The darkening skin tone in PIH actually presented a mixture of inflammatory erythema, angiogenesis, and hyperpigmentation. The inflammation and pigmentation phases of PIH were not sequential but partially overlap. The duration of suction blister-induced PIH is more than 24weeks. The inflammatory phase partially overlaps with the pigmentary phase, and those drugs with anti-inflammatory and anti-pigmentary dual effects are potential choices.

Inverse response behaviour in the bright ring radius measurement of the Czochralski process I: Investigation

This is the first part of a two-article series that deals with the investigation of the anomalous behaviour in the radius measurement signal of the Czochralski (Cz) process and its mitigation in a feedback control system. The inverse or anomalous behaviour is indeed a measurement signal response, which initially is opposite to that of the expected response. This is a crucial and limiting factor in feedback control system design. The paper presents the development of a rigorous 3D ray-tracing method to investigate the inverse response behaviour in the measurement signal. The results of this study provide an insight into the dynamic behaviour of the Cz growth process. It can serve as a guideline for achieving effective crystal radius control, which is addressed in the second part of this article series.

Diffraction on a Microbubble and the Morphology of the Silicon Surface Irradiated through Glycerol by a Pair of Femtosecond Laser Pulses

The effect of two successive laser pulses on silicon placed in glycerol has been studied experimentally and numerically with electromagnetic, hydrodynamic, and atomistic simulation programs. It has been shown that a microbubble in the liquid is formed on the surface after the first pulse; then, the second pulse whose width is comparable with the diameter of the microbubble is diffracted on this microbubble. The calculated diffraction pattern and light intensity distribution on the silicon surface indicate that the maximum intensity at the diffraction peaks can be noticeably higher than the intensity on the axis of the incident Gaussian beam. An increase in the intensity concentrated in one bright narrow ring around the microbubble results in the formation of a characteristic groove surrounded by ridges on silicon. The molecular dynamics simulation has shown that intense heating at the diffraction peak is responsible for the melting and displacement of the melt from the center of heating. This leads to the formation of grooves with ridges having a profile similar to that measured in the experiment.