Short Wavelength Research Articles

Electromagnetic TE- and TM-waves propagation in a plane waveguide covered with graphene characterized by nonlinear conductivity

Background. Guiding properties of waveguiding structures with graphene are of great importance for various applications and have been studied in many papers. In all such studies, graphene was characterized, as a rule, by linear surface conductivity. However, if the intensity of an electromagnetic wave is large enough, the interaction of graphene with the electromagnetic wave becomes nonlinear; in this case, it is more correct to describe graphene by nonlinear conductivity.
 Aim. This work is aimed at studying the influence of cubic nonlinearity of graphene, corresponding to the so-called self-action effects (not affecting the frequency of the incident wave), on the propagation of TE- and TM-polarized waves in the structure, which is a plain dielectric layer covered on one side by graphene.
 Methods. In this study, the guiding properties of the waveguide are studied using primarily an analytical approach. Thus, from Maxwell's equations, material equations and boundary conditions, a couple of dispersion equations for TE-and TM-polarized waves is derived and then its solvability is studied. In addition, some numerical experiments are carried out in the study.
 Results. The dispersion equations of the studied waveguiding structure for TE- and TM-polarized waves are derived in explicit form. Studying analytically obtained equations, conditions for waveguide parameters are found, providing the existence of a given number of waveguide modes. In addition, some numerical results are obtained in the paper, which give an idea of the influence of nonlinear effects on the electromagnetic waves propagating in the structure.
 Conclusion. The results obtained in this paper reveal two effects related to the cubic nonlinearity of graphene. Firstly, in a plain dielectric layer with graphene coating in the strong nonlinear regime TE-waves with longer wavelength and TM-waves with shorter wavelength propagate compared to electromagnetic waves that propagate in the same structure in the linear regime. Secondly, the strong cubic nonlinearity leads to a greater localization of the electromagnetic wave within the waveguiding structure.

Near-mid infrared spectroscopy of carbonaceous chondrites: Insights into spectral variation due to aqueous alteration and thermal metamorphism in asteroids

Carbonaceous chondrites (CCs) are windows into the early Solar System and the histories of their parent bodies. Their infrared spectral signatures are powerful proxies for deciphering their composition and evolution history, but still present formidable challenges in relation to determining the degree of secondary processing such as aqueous alteration and thermal metamorphism via comprehensive data and mid-infrared feature. In our study, we delved into the infrared spectra spanning 1–25 μm of 17 CCs, with distinct petrological characteristics and varying degrees of alteration. Through this investigation, we uncovered distinct spectral patterns that shed light on the processes of alteration and metamorphism. As aqueous alteration intensifies, two key spectral features, the 3 μm-region absorption feature associated with OH-bearing minerals and water, and the 6 μm band indicative of water molecules, both grow in intensity. Simultaneously, their band centers shift towards shorter wavelengths. Moreover, as alteration progresses, a distinctive absorption feature emerges near 2.72 μm, resembling the OH absorption feature found in serpentine and saponite minerals. Comparison of aqueous alteration to laboratory-heated CCs suggests that the 3 μm region OH/H2O absorption feature differs between CC heated to less than or more than ∼300 °C. Further insights are gained by examining the vibrational features of silicate minerals, notably influencing the 10 μm and 20 μm regions. The 12.4 μm /11.4 μm reflectance ratio diminishes, and the reflectance peak in the 9–14 μm range shifts towards shorter wavelengths. These changes are attributed to the transformation of anhydrous silicates into phyllosilicates. In the 15–25 μm region, the influence of thermal metamorphism becomes evident and results in the appearance of more spectral features, the single reflectance peak at 22.1 μm undergoes a transformation into two distinct peaks at 19 μm and 25 μm, which is primarily attributed to the increased presence of anhydrous silicates and olivine recrystallization. These findings offer novel insights into the volatile-rich compositions of C-complex asteroids and the thermal evolution histories of their parent bodies.

Analysis of the short wavelength range of QSOs

In this work we try to classify objects using the MgII 2798 Å line from optical spectra. For that, we use BZQ type objects from BZCAT catalogue. From SDSS catalogues we have 618 BZQ objects which have optical spectra and only in 139 objects there are MgII and Hβ lines simultaneously (z=0.3345-1.0915). By the shape of MgII lines, we grouped these spectra into 3 categories: Broad & Narrow, Broad+Narrow, and Broad.

Sun-as-a-star variability of Hα and Ca II 854.2 nm lines

Studies of stellar magnetic fields mostly rely on proxies derived from chromospheric lines, typically forming in the UV and shorter wavelengths and therefore accessible only from space based observatories. Even Ca II K or H observations, forming in regions accessible from the ground, are not always available. As a result, there is a crucial need to explore alternative activity proxies to overcome the limitations posed by observational constraints. Using sun-as-a-star observations acquired with the ISS at SOLIS we investigated the correlation between the Ca II K emission index and indices derived from the Hα 656.3 nm and Ca II 854.2 nm lines, which are well known chromospheric diagnostics. We found that both the core intensities and widths of the two lines are positively correlated with the Ca II K emission index (ρ ≳ 0.8), indicating their suitability as reliable indicators of magnetic activity, the width of the Hα line showing the highest correlation (ρ = 0.9). We also found that such correlations vary with the activity cycle. Specifically, during the analyzed cycle 24, the correlations with the Ca II K index varied 14% for the Hα width, 33% for the Hα core intensity, and doubled for the two Ca II 854.2 nm line indices. These results suggest that, among the investigated indices, the Hα width best traces magnetic activity. Results are discussed at the light of current knowledge of the formation heights of the two lines, and of spatially resolved solar observations.

Generation of superposed orbital angular momentum beams using a free-electron laser oscillator.

With wavelength tunability, free-electron lasers (FELs) are well-suited for generating orbital angular momentum (OAM) beams in a wide photon energy range. We report here the first experimental demonstration of OAM beam generation using an oscillator FEL with the tens of picosecond pulse duration. Lasing around 458 nm, we have produced the four lowest orders of superposed Laguerre-Gaussian beams using a very long FEL resonator of 53.73 m. The produced beams have good beam quality, excellent stability, and substantial average power. We have also developed a pulsed operation mode for these beams with a highly reproducible temporal structure for a range of repetition rate of 1-30 Hz. This development can be extended to short wavelengths, for example to x-rays using a future x-ray FEL oscillator. The OAM operation of such a storage-ring FEL also paves the way for the generation of OAM gamma-ray beams via inverse Compton scattering.

Discriminating early-stage diabetic retinopathy with subjective and objective perimetry.

To prevent progression of early-stage diabetic retinopathy, we need functional tests that can distinguish multiple levels of neural damage before classical vasculopathy. To that end, we compared multifocal pupillographic objective perimetry (mfPOP), and two types of subjective automated perimetry (SAP), in persons with type 2 diabetes (PwT2D) with either no retinopathy (noDR) or mild to-moderate non-proliferative retinopathy (mmDR). Both eyes were assessed by two mfPOP test methods that present stimuli within either the central ±15° (OFA15) or ±30° (OFA30), each producing per-region sensitivities and response delays. The SAP tests were 24-2 Short Wavelength Automated Perimetry and 24-2 Matrix perimetry. Five of eight mfPOP global indices were significantly different between noDR and mmDR eyes, but none of the equivalent measures differed for SAP. Per-region mfPOP identified significant hypersensitivity and longer delays in the peripheral visual field, verifying earlier findings. Diagnostic power for discrimination of noDR vs. mmDR, and normal controls vs. PwT2D, was much higher for mfPOP than SAP. The mfPOP per-region delays provided the best discrimination. The presence of localized rather than global changes in delay ruled out iris neuropathy as a major factor. mfPOP response delays may provide new surrogate endpoints for studies of interventions for early-stage diabetic eye damage.

Short wavelength infrared (SWIR) reflectance spectroscopy of alteration minerals of Qibaoshan ore district, Shandong Province, China

Qibaoshan is a recently discovered ore district including a significant epithermal deposit; it has three different types of deposits that have been developed in the Qibaoshan subvolcanic complex, including Jinxiantou copper–gold deposit, Qibaoshan polymetallic epithermal deposit and Diaoyutai pyrite deposit.The characteristics of these deposits and geochronological studies indicate that they may belong to the same mineral system. To study the relationship between the deposits and to determine potential for deposits under cover, surface alteration mapping by short-wave infrared spectroscopy (SWIR) analyses was conducted on the ore field. The results showed that the Jinxiantou copper–gold deposit has illite ＋ chlorite alteration, and the Qibaoshan deposit has illite + chlorite alteration as vein halos and gradually transitions outwards to montmorillonite alteration. Illite alteration is widely developed in the Qibaoshan ore field.Study of the spectral characteristics of illite in the east of the ore district showed it has a lower wavelength Al-OH absorption peak position (Pos2200) and higher illite crystallinity (IC) value and shows a trend of gradually decreasing Pos2200 and increasing IC to the west, indicating that the inferred heat center in the eastern ore district may be the center of hydrothermal activity. The Qibaoshan ore district contains a porphyry-epithermal hydrothermal mineral system, and the east of the ore district may have potential for discovery of porphyry deposits.

The Effect of Pyranine and MoS2 Content on the Optical Properties of Polyacrylamide-MoS2 Composite Gels

The most favorable members of the class of two-dimensional (2D) materials, molybdenum sulfide (MoS2), graphene, and tungsten disulfide (WS2) have become a thriving research frontier for many applications, ranging from catalysis to optoelectronic devices, due to their superior electronic behavior and mechanical properties. Making a new, smart, hydrogel when incorporating MoS2 into basic hydrogels can change their optical, electronic, and mechanical properties. In this work, MoS2-doped polyacrylamide (PAAm) gels were prepared via the free radical crosslinking copolymerization technique at room temperature without pyranine which is often used for crosslinking PAAm. The optical properties of PAAm-MoS2 composite gels were investigated, and they were analyzed using ultraviolet (UV) and fluorescence spectroscopy. The absorbance was measured before and after diffusion of MoS2-doped PAAm, and after the release of pyranine in and out of the composite gel, respectively. The shift of the absorption edge toward shorter wavelengths was seen when the quantity of MoS2 in the PAAm composite gels was decreased. The constituents included in the polymer composites exhibited notable photon energy absorption within the visible and ultraviolet spectra. This absorption phenomenon induced electron transitions to states of elevated energy. Parameters, such as refractive index and extinction coefficient, were analyzed with respect to the content of MoS2. When the MoS2 amount was increased in the gels, the percentage of reflectance increased. The extinction coefficient increased at longer wavelength and it decreased in the UV range, the shorter wavelength region. The results suggested that MoS2-doped PAAm composite gels show promising optoelectronic properties for developing optoelectronic devices.

Spectral Analysis of Human Retinal Pigment Epithelium Cells in Healthy and AMD Eyes.

Retinal pigment epithelium (RPE) cells show strong autofluorescence (AF). Here, we characterize the AF spectra of individual RPE cells in healthy eyes and those affected by age-related macular degeneration (AMD) and investigate associations between AF spectral response and the number of intracellular AF granules per cell. RPE-Bruch's membrane flatmounts of 22 human donor eyes, including seven AMD-affected eyes (early AMD, three; geographic atrophy, one; neovascular, three) and 15 unaffected macula (<51years, eight; >80years, seven), were imaged at the fovea, perifovea, and near-periphery using confocal AF microscopy (excitation 488nm), and emission spectra were recorded (500-710nm). RPE cells were manually segmented with computer assistance and stratified by disease status, and emission spectra were analyzed using cubic spline transforms. Intracellular granules were manually counted and classified. Linear mixed models were used to investigate associations between spectra and the number of intracellular granules. Spectra of 5549 RPE cells were recorded. The spectra of RPE cells in healthy eyes showed similar emission curves that peaked at 580nm for fovea and perifovea and at 575 and 580nm for near-periphery. RPE spectral curves in AMD eyes differed significantly, being blue shifted by 10nm toward shorter wavelengths. No significant association coefficients were found between wavelengths and granule counts. This large series of RPE cell emission spectra at precisely predefined retinal locations showed a hypsochromic spectral shift in AMD. Combining different microscopy techniques, our work has identified cellular RPE spectral AF and subcellular granule properties that will inform future in vivo investigations using single-cell imaging.

High performance type-II InAs/GaSb superlattice infrared photodetectors with a short cut-off wavelength

High performance type-II InAs/GaSb superlattice infrared photodetectors with a short cut-off wavelength

Design, construction and robust validation of a germicidal device based on UV irradiation: a necessity for hospital disinfection in the COVID-19 era

Pandemic by SARS-CoV-2 has revealed the importance of disinfection methods due to pathogens of medical importance being detectable and infective after several hours on contaminated surfaces, including medical devices. The aim of this work was to design, construction, and validation of a UVC light irradiation system in the short wavelength region (200 to 320 nm). We studied the effective of the system through in vitro disinfection to eliminate pathogens such as SARS-CoV-2, ESKAPE bacteria and fungi in biofilm and planktonic forms. Doses of 0.25 J/cm2 (10 s of exposure to UVC light), 100% death of ESKAPE bacteria and fungi in planktonic form was observed. Through biofilm formation induction assays of these microorganisms showed resistance to treatment with UV light; however, their viability was not detected after 20 s of exposure (via confocal microscopy). For SARS-CoV-2, 100% reduction was reached after 120 s of exposure. This evidence shows the need to employ emerging methods of disinfection of surfaces and medical devices since these are potential vehicles for transmitting pathogens. The advantages of using UV light as an emergent disinfection method in the era of COVID-19 are discussed.

Co-estimation of core and lithospheric magnetic fields by a maximum entropy method

SUMMARY Satellite observations of the geomagnetic field contain signals generated in Earth’s interior by electrical currents in the core and by magnetized rocks in the lithosphere. At short wavelengths the lithospheric signal dominates, obscuring the signal from the core. Here we present details of a method to co-estimate separate models for the core and lithospheric fields, which are allowed to overlap in spherical harmonic degree, that makes use of prior information to aid the separation. Using a maximum entropy method we estimate probabilistic models for the time-dependent core field and the static lithospheric field that satisfy constraints provided by satellite observations while being consistent with prior knowledge of the spatial covariance and expected magnitude of each field at its source surface. For the core field, we find that between spherical harmonic degree 13 and 22 power adds coherently to the established structures, and present a synthetic test that illustrates the aspects of the small scale core field that can reliably be retrieved. For the large scale lithospheric field we also find encouraging results, with the strongest signatures below spherical harmonic degree 13 occurring at locations of known prominent lithospheric field anomalies in the northern part of Eastern Europe, Australia and eastern North America. Although the amplitudes of the small scale core field and large scale lithospheric field are likely underestimated we find no evidence that obvious artefacts are introduced. Compared with conventional maps of the core–mantle boundary field our results suggest more localized normal flux concentrations close to the tangent cylinder, and that low latitude flux concentrations occur in pairs with opposite polarities. Future improvements in the recovery of the small scale core field and large scale lithospheric field will depend on whether more detailed prior information can be reliably extracted from core dynamo and lithospheric magnetization simulations.

Short wavelength light absorption and conversion films containing carbon nanodots for light damage prevention

The carbon nanodots (CNDs) can absorb short wavelength light and enable excited electrons to achieve light conversion to long wavelength emission by radiative transition, while accompanying the non-radiative transition of excited electrons, in order to block the short wavelength light. The CNDs were prepared from chitosan as the carbon source, and then mixed with polyvinyl alcohol (PVA) to prepare CNDs-based optical blocking films (CND-OBFs) containing different proportions of CNDs. Images were clearly visible through CND-OBFs under both close and long-distance observation, demonstrating good transparency. The CND-OBFs were shown to block both UV light from sunlight and harmful blue light from computers, mobile phones and white light-emitting diodes. The CND-OBFs can thus be used to effectively block short wavelength light. Samples of wood were covered with different CND-OBFs and the wood surfaces were then irradiated with UV light (340 nm, 80 W). The results show that different CND-OBFs block short wavelength light to different extents; CND-OBF containing 15.7 % CNDs can completely block short wavelength light through absorption and conversion, protecting the wood samples from discoloration. This work provides a new research approach in which CNDs are used to protect wood by blocking short wavelength light.

Localised loss of sheen in Optos pseudocolour images in Oguchi disease following prior short wavelength autofluorescence imaging

Aims/Purpose: Oguchi disease is characterized by night blindness and a striking golden retinal sheen in the light‐adapted state which disappears following prolonged dark adaptation (Mizuo‐Nakamura phenomenon). The sheen is observable clinically and on colour and pseudocolour (Optos plc) imaging. We observed a localized loss of sheen in a patient on colour/pseudocolour imaging in an area corresponding to the 30 degree square illuminated by short wavelength (488 nm) autofluorescence (AF) imaging (Heidelberg Spectralis). We explored whether other cases showed this phenomenon.Methods: Patients in our service with Oguchi disease (diagnosed phenotypically and/or with genetic confirmation) who had undergone colour or pseudocolour imaging were identified. In these patients, note was made of whether prior 30 degree short wavelength autofluorescence images had been undertaken and whether a localized square‐shaped loss of sheen was observed.Results: We identified 13 patients who had undergone colour or pseudocolour imaging. Of these, 4 patients (2 males, 2 females) had undergone prior 30 degree (and not 55 degree) short wavelength AF imaging at the same visit (ages ranging from 12 to 67). In 2 patients (a 12 year old, with variants in GRK1, and a 67 year old, not yet genotyped), a clear central square in which the sheen was absent was observed in the colour or pseudocolour images.Conclusions: The phenomenon of disappearance of the sheen in Oguchi disease following prolonged darkness is well‐described. Paradoxically, we observed loss of the sheen in 2 patients in a defined area corresponding to the field of illumination by bright blue light in 30 degree AF imaging. The blue light is preferentially absorbed by rhodopsin, which becomes bleached. It is possible that the sheen (at least in some patients) is dependent on there being a large proportion of unbleached rhodopsin as well as deficient shut‐off of activated rhodopsin.

Tunable ultraviolet laser based on intracavity third harmonic generation of external cavity surface emitting laser

Ultraviolet laser has high frequency, short wavelength, large single-photon energy, and high spatial resolution, and has wide applications in many fields such as fine processing, life sciences, and spectroscopy. In this work, a wavelength tunable ultraviolet laser based on intracavity third harmonic generation from an external-cavity surface-emitting laser is reported. The W-type resonant cavity of the laser is composed of a distributed Bragg reflector (DBR) at the bottom of the gain chip, three plane-concave mirrors, and a rear plane mirror. On the arm containing the gain chip, a birefringent filter is inserted at the Brewster angle as the polarization and wavelength tuning element, which can also narrow the linewidth of the fundamental laser to a certain extent. A type-I phase-matched LBO crystal is placed on the beam waist between the folding mirrors M2 and M3 to convert the 980 nm fundamental laser into 490 nm blue light, and a type-I phase-matched BBO crystal is inserted in the beam waist near the rear mirror to produce a 327 nm ultraviolet output from the remained 980 nm fundamental laser and the frequency-doubled 490 nm second harmonic. Before the BBO crystal, a half-wave plate at 980 nm is employed to change the polarization of the fundamental laser, so as to meet the type-I phase-matching condition of the used BBO crystal. Owing to the larger nonlinear coefficient of the type-I phase-matched BBO crystal, and its obviously higher transmittance at 327 nm wavelength than the usually used LBO crystal, the output power is obtained to be 538 mW at 327 nm ultraviolet wavelength, corresponding to a conversion efficiency of 1.1% from pump light to ultraviolet laser. The experiment is performed under conditions of 15 ℃ temperature, 47 W absorbed pump power, 5 mm-length LBO and 5 mm-length BBO crystals. By using a 2 mm-thick birefringent filter as the tuning element, 34.1 nm tuning range of the 980 nm fundamental laser, 14.3 nm tuning range of the 490 nm second harmonic, and 8.6 nm tuning range of the 327 nm third harmonic are obtained. The ultraviolet laser exhibits good beam quality as well as acceptable power stability with the maximum power fluctuation less than 2% within 4.5 h.

Titanium nitride-based hyperbolic metamaterial for near-infrared ultrasensitive sensing of microbes.

We demonstrate an ultrasensitive microbe sensor for the first time using a titanium nitride (TiN) nanowire-based hyperbolic metamaterial (HMM) structure. We detected the change in the resonance wavelength shift due to the inclusion of microbes in a freshwater environment employing the finite-difference time-domain (FDTD) method. Our proposed HMM sensor exhibits strong bulk plasmon polariton (BPP) modes in the anisotropic hyperbolic regime (λ ≥ 590 nm) and operates in the near-infrared (NIR) wavelength region. We studied the impact of structural parameters on the resonance wavelength shift, where our proposed HMM sensor structure exhibited an outstanding sensing capability of 11 nm per bacteria. A limit of detection of 0.00008 RIU was achieved for our proposed HMM sensor structure. Additionally, we verified our results theoretically to calculate mode frequency shift by solving the effective medium theory (EMT). Our study revealed that HMM is the origin of highly sensitive BPP modes. We obtained two BPP modes, where the BPP mode at a longer wavelength (q = 1) exhibited the highest resonance wavelength shift compared to the BPP mode at a shorter wavelength (q = 2). More importantly, we demonstrated numerically the point-detection capability of our proposed HMM microbe sensor structure, which was unattainable in previously reported sensor work. Moreover, this sensor can be adapted to detect different viruses and bacteria. Our proposed TiN-based HMM structure can potentially be an ultrasensitive and straightforward microbe sensor for label-free detection.

Fused Low-Earth-Orbit GNSS

Traditional Global Navigation Satellite System (GNSS) immunity to interference may be approaching a practical performance ceiling. Greater gains are possible outside traditional GNSS orbits and spectrum. GNSS from low Earth orbit (LEO) has long been viewed as promising but expensive, requiring large constellations for rapid navigation solutions. The recent emergence of commercial broadband LEO mega-constellations invites study on dual-purposing these for both communications-their primary mission-and a secondary positioning, navigation, and timing (PNT) service. Operating at shorter wavelengths than traditional GNSS, these constellations would permit highly directive, relatively compact receiver antennas. PNT-specific on-orbit resources would not be required: the transmitters, antennas, clocks, and spectrum of the hosting broadband network would suffice for PNT. Non-cooperative use of LEO signals for PNT is an option, but cooperation with the constellation operator (&#x201C;fusion&#x201D; with its communications mission) eases the burden of tracking a dense, low-altitude constellation from the ground and enables a receiver to produce single-epoch stand-alone PNT solutions. This paper proposes such a cooperative concept, termed fused LEO GNSS. Viability hinges on opportunity cost, or the burden a secondary PNT mission imposes on the communications constellation operator. This is assessed in terms of time-space-bandwidth product and energy budget. It is shown that a near-instantaneous-fix PNT service over &#x00B1;60&#x00B0; latitude (covering 99.8% of the world's population) with positioning performance superior to traditional GNSS pseudoranging would cost less than 1.6% of downlink capacity for the largest of the new constellations, SpaceX&#x0027;s Starlink. This allocation is comparable to adding one user consuming 5.7 Mbps of broadband service to each cell.

Modelling the dust emission of a filament in the Taurus molecular cloud

Context. Dust emission is an important tool in studies of star-forming clouds as a tracer of column density. This is done indirectly via the dust evolution that is connected to the history and physical conditions of the clouds. Aims. We examine the radiative transfer (RT) modelling of dust emission over an extended cloud region, using a filament in the Taurus molecular cloud as an example. We examine how well far-infrared (FIR) observations can be used to determine both the cloud and the dust properties. Methods. Using different assumptions on the cloud shape, radiation field, and dust properties, we fit RT models to Herschel observations of the Taurus filament. We made further comparisons with measurements of the near-infrared extinction. The models were used to examine the degeneracies between the different cloud parameters and the dust properties. Results. The results show a significant dependence on the assumed cloud structure and the spectral shape of the external radiation field. If these are constrained to the most likely values, the observations can be explained only if the dust FIR opacity has increased by a factor of 2–3 relative to the values in diffuse medium. However, a narrow range of FIR wavelengths provides only weak evidence of the spatial variations in dust, even in the models covering several square degrees of a molecular cloud. Conclusions. The analysis of FIR dust emission is affected by several sources of uncertainty. Further constraints are therefore needed from observations at shorter wavelengths, especially with respect to trends in dust evolution.

JWST Imaging of Edge-on Protoplanetary Disks. II. Appearance of Edge-on Disks with a Tilted Inner Region: Case Study of IRAS04302+2247

We present James Webb Space Telescope imaging from 2 to 21 μm of the edge-on protoplanetary disk around the embedded young star IRAS04302+2247. The structure of the source shows two reflection nebulae separated by a dark lane. The source extent is dominated by the extended filamentary envelope at ∼4.4 μm and shorter wavelengths, transitioning at 7.7 μm and longer wavelengths to more compact lobes of scattered light from the disk itself. The dark lane thickness does not vary significantly with wavelength, which we interpret as an indication for intermediate-sized (∼10 μm) grains in the upper layers of the disk. Intriguingly, we find that the brightest nebula of IRAS40302 switches side between 12.8 and 21 μm. We explore the effect of a tilted inner region on the general appearance of edge-on disks. We find that radiative transfer models of a disk including a tilted inner region can reproduce an inversion in the brightest nebula. In addition, for specific orientations, the model predicts strong lateral asymmetries, which can occur for more than half possible viewing azimuths. A large number of edge-on protoplanetary disks observed in scattered light show such lateral asymmetries (15/20), which suggests that a large fraction of protoplanetary disks might host a tilted inner region. Stellar spots may also induce lateral asymmetries, which are expected to vary over a significantly shorter timescale. Variability studies of edge-on disks would allow us to test the dominant scenario for the origin of these asymmetries.

Enhanced NIR optical property of single-site-occupied ultra-broadband InNbTiO6:Cr3+ phosphor at 965 nm through Ga3+ doping

Most near-infrared (NIR) phosphors suffer from short emission wavelength (&lt; 1000 nm) and narrow full width at half maximum (FWHM) values below 200 nm, restricting their broader applications in non-destructive...