Diffuse Component Research Articles

Poster Session II: Image features involved in translucency enhancement by chromaticity information.

Previous studies have reported that chromaticity information in object images enhances perceived translucency. The aim of this study, was to elucidate how color forms image features that contribute to translucency in psychophysical experiments. The stimuli were computer-graphics images of translucent objects with different spectral scattering coefficients (i.e., hues) and various optical and geometrical parameters. Achromatic images with the same luminance as the chromatic images were also created. Perceived translucency was measured using Thurston's pairwise comparison, and the effect of chromaticity or translucency was evaluated by comparing translucency in achromatic and chromatic images. The results showed higher perceived translucency for the chromatic object images than the achromatic ones. Subsequently, we analyzed how different image features correlate with the effects of color on translucency using multiple regression analysis. The result indicated that the luminance- chromaticity correlation, which has been proposed as a potential cue for translucency could hardly explain the color effects. Rather, we found that the change in brightness contrast in the diffuse components modulated by the Helmholtz-Kohlrausch (H-K) effect was strongly and negatively correlated with the color effects. These results suggest that some image features, which covary with brightness contrast brightness contrast, contribute to the color effects on translucency.

Entrainment and bulk flow characteristics of heated and unheated transient plumes using direct numerical simulations

An off-source volumetrically heated turbulent transient plume, known as transient diabatic plume (TDP), is compared with an unheated transient plume (TP). Both the TDP and TP are simulated using direct numerical simulations at a source Reynolds number (Re) of 2000. The flow is sufficiently resolved till the Kolmogorov (η) scale. The radius of the TP shows a self-similar behavior of linear increase with height after about five diameters from the source hot-patch. However, the velocity does not show a self-similar behavior. The addition of off-source buoyancy in the TDP triples the vertical velocity and also causes an order of magnitude increase in the vorticity magnitude (ω) due to the effect of the baroclinic torque. Compared to the TP, the entrainment coefficient and radius of the TDP increase and this shows enhanced entrainment due to heating. The transient flows fields are analyzed using local scales based on integral quantities of volume, momentum, and buoyancy. Normalizing the vorticity with these integral scales results in a more uniform scaled ωl for both flows. Hence, for both TP and TDP, we use the same values of ωl to quantify the inner and outer boundaries of the turbulent non-turbulent layer (TNTL). The width of the TNTL (δTNTL) decreases by ∼25% due to heating. The conditionally averaged velocity profiles suggest that very close to the outer irrotational boundary (IB) of the TNTL, the TDP exhibits stronger updrafts and downdrafts in comparison to the TP. Entrainment is studied using the mean relative velocity (⟨vn⟩) defined at the IB. The analysis of the components of ⟨vn⟩ reveal that the viscous diffusion component, which is of the order of the Kolmogorov velocity (uη), is balanced by the baroclinic and viscous dissipation components, while the inviscid term is negligible in comparison.

Cortical microstructural MRI for detection of early target engagement in AD drug trials: post‐hoc analysis of exploratory outcomes from a Phase 1b safety study for XPro1595 in AD

AbstractBackgroundEvidence in support of the amyloid cascade hypothesis for Alzheimer’s disease (AD) suggests that pathological amyloid‐beta (Aβ) is initially associated with synaptic hyperactivity and accumulates in an activity dependent fashion. These findings are corroborated by longitudinal data from cohort studies with Aβ‐PET imaging, wherein Aβ accumulates first in gray matter (GM) cortices associated with the default‐mode network (DMN) before spreading in a semi‐hierarchical pattern to different neocortical regions as the disease progresses (Mattsson et al. 2019). Mapping brain regions most frequently affected by Aβ pathology at different stages of disease may provide a framework for investigation of new drug entities targeting other components of Aβ toxicity using less invasive imaging modalities. The hypothesis here is that indicators of disease specific, tissue‐level treatment effects should be first detectable in brain regions most frequently affected by active pathology.MethodXPro1595 is a selective, brain penetrant neutralizer of soluble TNF with potent anti‐neuroinflammatory effects recently assessed for safety and pharmacological activity in a small, open‐label phase‐1b dose finding study (NCT03943264) in patients with AD. Clinical trial results for patients (n = 9) with analyzable dMRIs who completed 12‐weeks of treatment with XPro1595 [0.3 mg/kg; n = 3) or (1.0 mg/kg; n = 6)] met criteria for post‐hoc analysis. Exploratory outcomes included the novel cortical diffusivity measurement PerpPD+. PerpPD+ represents the diffusion components perpendicular to cortical GM minicolumns, indicates microscopic disruption when increased, and has proven more sensitive than standard volumetrics to changes in indicators of synaptic function, neuroinflammation and neurodegeneration across the AD continuum.ResultMean MMSE scores at baseline were 23.7 (SD = 2.5) and 15.8 (SD = 7.0) in the low‐dose and high‐dose groups, respectively, indicating varying degrees of severity. Week‐12 results showed decreases in bilateral PerPD+ at the whole brain level and in multiple GM cortices documented in the literature with the highest frequency of early (precuneus, isthmus cingulate, posterior cingulate, insula, and lateral and medial orbitofrontal) and late (lingual, pericalcarine, paracentral, precentral, and postcentral) Aβ accumulation (Figures1‐2).ConclusionCortical diffusivity measurements related to minicolumnar microstructure may provide an opportunity for noninvasive detection of early, disease specific, tissue‐level target engagement in clinical trials for investigational new drugs in AD.

Clinical and biomarker correlates of region‐specific diffusion MRI metrics in a short‐term, Phase 1b clinical trial for XPro1595 in Alzheimer’s disease

AbstractBackgroundXPro1595 is a selective, brain penetrant neutralizer of soluble TNF with potent anti‐neuroinflammatory effects recently assessed for safety and pharmacological activity in a 12‐week, phase‐1b open‐label dose finding study in patients with AD (NCT03943264). An unbiased screen of imaging outcomes revealed signals for target engagement in gray matter (GM) cortices documented in the literature as regions most frequently affected by accumulation of amyloid‐beta (Aβ) in early and late phases of AD (Mattsson et al. 2019). Post‐hoc analyses were conducted to further investigate these signals.MethodStudy results for patients (n = 9; MMSE range: 8‐27) with analyzable dMRIs who completed 12‐weeks of treatment with XPro1595 [0.3 mg/kg; n = 3) or (1.0 mg/kg; n = 6)] met inclusion criteria. Correlation matrices (uncorrected Pearson’s r) were created to compare key secondary and exploratory imaging outcomes to clinical characteristics and CSF biomarkers of AD specific pathology (Roche Elecsys NeuroToolKit). Imaging outcomes included white matter free‐water (WM‐FW) as a prespecified proxy for neuroinflammation, and GM PerpPD+. PerpPD+ represents the diffusion components perpendicular to cortical GM minicolumns and serves as an indicator of worsening GM microarchitecture when increased in AD. Due to the small sample size, the threshold for identification of informative values was set at P<0.05.ResultAt baseline, PerpPD in GM regions associated with early Aβ accumulation (insula, precuneus, isthmus and posterior cingulate, and lateral‐orbitofrontal cortices), and WM‐FW in the cingulum bundle, showed strong associations with CSF biomarkers of neurodegeneration (pTau and tTau), inflammatory gliosis (YKL‐40, GFAP and sTREM2), cognitive status (MMSE scores) and disease duration (Table1). Week‐12 results showed decreased PerpPD+ and WM‐FW in these regions, with a dose‐dependent signal concentrated in the isthmus cingulate GM and cingulum WM. Isthmus cingulate PerpPD+ ∆ (%) correlated positively with baseline Aβ42/40 and MMSE (Figure1), and negatively with duration of disease and cingulum WM‐FW, whereas cingulum WM‐FW ∆ (%) corelated with baseline pTau and tTau (Table 2).ConclusionPerpPD+ in isthmus cingulate GM and WM‐FW in cingulum WM represent potential indicators of disease activity sensitive to early treatment effects in small, proof of concept clinical trials for AD. Additional research is warranted to further elucidate these signals.

Evaluation of Horizontal Single‐Axis Solar Tracker Algorithms in Terms of Energy Production and Operational Performance

Horizontal single‐axis solar tracking systems with Astronomical tracking algorithm are commonly used in photovoltaic (PV) installations. However, different algorithms can increase the PV installation's performance without implementing new equipment or technologies. In this article, the performance of three tracking algorithms is compared to the Astronomical one. Two algorithms aim at optimizing the received irradiance focusing on the diffuse component. The third one, called Analytical, is presented as a new development in this study, defining the optimal inclination angle depending on all radiation components. The comparison focuses on different parameters like the in‐plane irradiance, DC power output from a monofacial PV system and operational aspects like the performed number of movements. High‐time‐resolution (1 min) simulations are performed with proprietary software taking into account several effects on the effective irradiance and power output estimation, such as shading effects or PV configuration. Eight locations with different climatic conditions are analyzed. All three algorithms derive in higher in‐plane irradiance and power output values than the Astronomical algorithm, although the gain depends on the climatic conditions. At locations with high diffuse fraction, the power output from the Analytical algorithm, which outperforms the others, can be up to 3% higher than the Astronomical one.

Improving the Estimation of the Diffuse Component of Photosynthetically Active Radiation (PAR)

AbstractMost weather forecasting models are not able to accurately reproduce the great variability existing in the measurements of the diffuse component of photosynthetically active radiation (PAR; 400–700 nm) under all sky conditions. Based on the well‐known relationship between the diffuse fraction (k) and the clearness index (kt), this study addresses improvements in estimations by proposing adaptations of previous models, which were previously applied only to the total solar irradiance (TSI; 280–3,000 nm). In order to reproduce this variability, additional parameters were introduced. The models were tested employing a multisite database gathered at the Mediterranean basin. Since Artificial Neural Network (ANN) models are not limited to fixed coefficients to predict the diffuse fraction of PAR (kPAR), these types of models are more accurate than empirical ones, reaching determination coefficients (r2) up to 0.998. However, the simpler linear model proposed by Foyo‐Moreno et al. (2018), https://doi.org/10.1016/j.atmosres.2017.12.012 shows a similar performance to the ANN models, directly predicting the diffuse component of PAR (PARDiffuse) from TSIDiffuse, with a r2 up to 0.997. Results obtained here also determine that the most important variables for estimating PARDiffuse are kt or kt,PAR, and the apparent solar time (AST). Therefore, PARDiffuse can be modeled using TSI measured in most radiometric stations, reaching r2 up to 0.858 for empirical models and 0.970 for ANN models. This modified approach will allow for the very accurate construction of long‐term data series of PARDiffuse in regions where continuous measurements of PAR are not available.

NIMG-55. PREDICTING SITES OF TUMOR PROGRESSION IN THE INVASIVE MARGIN OF GLIOBLASTOMAS (PRAM-GBM STUDY): AN INTERIM ANALYSIS OF A MULTI-CENTER IMAGING BIOMARKER STUDY

Abstract INTRODUCTION Although glioblastoma cells extend throughout the brain, virtually all patients die from local progressive disease. This progressive tumor occurs at the resection margins and usually within the high-dose radiotherapy field. If we could identify where the tumor would progress, we could consider personalizing radiotherapy and surgical targets. Previous work has shown diffusion tensor MR as a potential biomarker of occult invasion. Biopsy studies reveal that the q-anisotropic component correlates with high-density tumor, and the extent of resection correlates with improved survival. We hypothesize that this is a biomarker that can predict where glioblastomas may progress. STUDY DESIGN: A multicentre, pragmatic, longitudinal observational cohort study from 6 centers. This is a planned interim analysis of the first cohort. METHODS Patients with glioblastomas suitable for maximal resection were imaged pre-operatively with a diffusion tensor MRI protocol. This was processed using a tensor decomposition method to generate the q-anisotropic component. Masks of the abnormal q-component were overlaid on the masks of new areas of contrast enhancement at progression (ground truth). Intersecting voxels were classified as true positive, true negative, false positive, and false negative, and the sensitivity and specificity were calculated. RESULTS 139 patients were recruited, but 50 were withdrawn. The interim analysis was planned for the first 2/3rds of the cohort (55 patients). Combining q and contrast enhancement provided the best predictor of site of tumor progression with a mean sensitivity of 79% [95%CI: 71-88%] compared to contrast enhancement of only 50% [95%CI: 39-61%]. Specificity remained high in both groups (CE+q mean 94% [95%CI: 93-95%] vs. CE alone 98% [95%CI: 97-98%]). CONCLUSION The anisotropic diffusion component, q, provides the best biomarker for identifying ‘residual tumor.’ This biomarker will form the basis of an early phase surgical trial IDEAL Stage 1 and 2a study to change surgical resection target.

The V˙O2max Legacy of Hill and Lupton (1923)-100Years On.

One hundred years ago, Hill and Lupton introduced the concept of maximal oxygen uptake (V˙O2max), which is regarded as "the principal progenitor of sports physiology." We provide a succinct overview of the evolvement of research on V˙O2max, from Hill and Lupton's initial findings to current debates on limiting factors for V˙O2max and the associated role of convective and diffusive components. Furthermore, we update the current use of V˙O2max in elite endurance sport and clinical settings. Practical Applications and Conclusions: V˙O2max is a healthy and active centenarian that remains a very important measure in elite endurance sports and additionally contributes as an important vital sign of cardiovascular function and fitness in clinical settings. Over the past 100years, guidelines for the test protocols and exhaustion criteria, as well as the understanding of limiting factors for V˙O2max, have improved dramatically. Presently, possibilities of accurate and noninvasive determination of the convective versus diffusive components of V˙O2max by wearable sensors represent an important future application. V˙O2max is not only an indicator of cardiorespiratory function, fitness, and endurance performance but alsorepresents an important biomarker of cardiovascular function and health to be included in routine assessment in clinical practice.

Pancreatic Cancer and Its Mimics.

Pancreatic ductal adenocarcinoma (PDAC) is the most common primary pancreatic malignancy, ranking fourth in cancer-related mortality in the United States. Typically, PDAC appears on images as a hypovascular mass with upstream pancreatic duct dilatation and abrupt duct cutoff, distal pancreatic atrophy, and vascular encasement, with metastatic involvement including lymphadenopathy. However, atypical manifestations that may limit detection of the underlying PDAC may also occur. Atypical PDAC features include findings related to associated conditions such as acute or chronic pancreatitis, a mass that is isointense to the parenchyma, multiplicity, diffuse tumor infiltration, associated calcifications, and cystic components. Several neoplastic and inflammatory conditions can mimic PDAC, such as paraduodenal "groove" pancreatitis, autoimmune pancreatitis, focal acute and chronic pancreatitis, neuroendocrine tumors, solid pseudopapillary neoplasms, metastases, and lymphoma. Differentiation of these conditions from PDAC can be challenging due to overlapping CT and MRI features; however, certain findings can help in differentiation. Diffusion-weighted MRI can be helpful but also can be nonspecific. Accurate diagnosis is pivotal for guiding therapeutic planning and potential outcomes in PDAC and avoiding biopsy or surgical treatment of some of these mimics. Biopsy may still be required for diagnosis in some cases. The authors describe the typical and atypical imaging findings of PDAC and features that may help to differentiate PDAC from its mimics. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Zins in this issue.

Chemical reaction motifs driving non-equilibrium behaviours in phase separating materials.

Chemical reactions that couple to systems that phase separate have been implicated in diverse contexts from biology to materials science. However, how a particular set of chemical reactions (chemical reaction network, CRN) would affect the behaviours of a phase separating system is difficult to fully predict theoretically. In this paper, we analyse a mean field theory coupling CRNs to a combined system of phase separating and non-phase separating materials and analyse how the properties of the CRNs affect different classes of non-equilibrium behaviour: microphase separation or temporally oscillating patterns. We examine the problem of achieving microphase separated condensates by statistical analysis of the Jacobians, of which the most important motifs are negative feedback of the phase separating component and combined inhibition/activation by the non-phase separating components. We then identify CRN motifs that are likely to yield microphase by examining randomly generated networks and parameters. Molecular sequestration of the phase separating motif is shown to be the most robust towards yielding microphase separation. Subsequently, we find that dynamics of the phase separating species is promoted most easily by inducing oscillations in the diffusive components coupled to the phase separating species. Our results provide guidance towards the design of CRNs that manage the formation, dissolution and organization of compartments.

Regime-dependent 1-min irradiance separation model with climatology clustering

Since directly measuring beam and diffuse irradiance is not feasible on many occasions, one often has to resort to estimating the beam and diffuse irradiance components from the global irradiance, which is known as separation modeling. Separation modeling is essentially a nonlinear regression problem, with the clearness index being the main input and the diffuse fraction being the output. Hundreds of separation models with various complexities have been proposed, among which the Yang4 model was recently validated using worldwide data as the quasi-universal choice for 1-min data. In this work, Yang4 is further improved by regime-dependent fitting, i.e., fitting a separate set of model coefficients for each climatological regime. Different regimes are determined through clustering of cloud cover frequency, aerosol optical depth, and surface albedo climatology maps. The new Yang5 model is able to outperform its predecessor at the 126 stations tested, covering a wide range of climate types. Overall, the normalized root mean square errors for beam normal irradiance (BNI) and diffuse horizontal irradiance (DHI) of Yang5 are 17.55% and 32.92% on average, as compared to 19.13% and 34.94% for the next best model, namely, Yang4. Furthermore, through conducting pairwise Diebold–Mariano tests, Yang5 is shown superior to Yang4 at 110/126 sites for BNI prediction and 93/126 for DHI.

Analysis of the solar radiation/atmosphere interaction at a Mediterranean site: The role of clouds

This study is the last of a series of three research papers analysing the solar radiation and its interaction with the atmospheric components spanning an eleven-year period (2008–2018) at a mid-latitude urban site in the Mediterranean basin. During the previous works a detailed characterization of the photosynthetically active radiation (PAR; 400–700 nm), as well as analysis the aerosol and clouds effects on PAR was carried out. This research work addresses an analysis of solar radiation on the total solar irradiance spectrum (TSI; 280–3000 nm) in terms of the effects of different atmospheric conditions on it, considered by the clearness index and the cloud cover, bringing very valuable findings from the long-term comparative analysis of radiative effects of clouds on TSI and PAR wavelength ranges. The average values in the entire period of the study for the global solar radiation in the total solar irradiance (TSIGlobal) found to be 450 ± 100 Wm−2 and 530 ± 110 Wm−2 under all and clear- sky conditions, respectively. Meanwhile, the average values for the diffuse component (TSIDiffuse) are 141 ± 21 Wm−2 and 130 ± 21 Wm−2 (all and clear skies, respectively), with a relatively low interannual variation up to 11% for both global and diffuse TSI, as well as for both sky conditions. Analysis on the total cloud cover (TCC) shows that the clearness index is not a good parameter to discriminate between all and clear sky conditions, since there is a marked overlap in the ranges of the kt values for the different categories of TCC. Additionally, the cloud radiative forcing (CRF) are computed as the difference in solar radiation measured under all and clear sky conditions. A high seasonal variability is found for CRF, where CRFTSI,Global ranges between −37.6 Wm−2 and -137.4 Wm−2, while CRFTSI,Diffuse from 4.4 Wm−2 to 22.6 Wm−2. The positive sign implies increase in solar radiation at the surface, while the negative one implies the opposite, i.e., less availability of solar radiation on the surface. Finally, the analysis of the annual evolution of CRF reveals a downward trend on CRFTSI and CRFPAR, for both global and diffuse This relevant finding implies that clouds are exerting less cooling effects over time at this Mediterranean site.

Features of ion exchange between the electrodes in metal-ion batteries during discharge

The importance and relevance of the storage of electrical energy is confirmed by events in the world and trends in the development and use of various electrical energy systems, household appliances, computer equipment, communication devices, etc. In addition to the growth of the metal-ion battery markets, there are trends towards a search for metals that in the future will be inexpensive and will have characteristics required for storage systems. This paper considers ion exchange between the electrodes of metal-ion batteries whose charge carriers are metal ions, which diffuse in the process of discharge from the negative electrode to the positive one. A mathematical model was developed and tested. The model is based on a system of diffusion transport equations with the Nernst–Planck–Poisson potential equation replaced by an equivalent conductivity potential equation. Quasi-equilibrium regimes are considered. The entire working area consists of a pore electrode space and a neutral separator. The mathematical model employed consists of potential distribution equations and an electrolyte concentration distribution equation supplemented by the dependence of the electrode surface current on the overvoltage and equations that determine the electrode pore structure depending on the masses transferred inside the electrode. The electric potential and diffuse component mass transfer equations are written within the framework of the modern theory of effective electrical conductivity in batteries with account for current exchange between the solid electrodes and the liquid electrolyte. The research results showed the following. A change in the resistance of the separator (a change in porosity) has little effect, if any, on the electrode current densities, but it causes some change in the potentials themselves. A change in the resistance of the electrolyte affects both the electrode potentials and the internal current distribution between the electrodes and the electrolyte.

Magnetic and Electrical Characteristics of Nd3+ and Mn2+-Co-doped Calcium Molybdato-Tungstates Single Crystals.

Single crystals of Ca1-3x-yMny□xNd2x(MoO4)1-3x(WO4)3x molybdato-tungstates (□ denotes vacant sites) with a scheelite-type structure have been successfully grown by the Czochralski technique in an inert atmosphere. This paper presents the results of structural, optical, magnetic, and electrical properties, as well as the broadband dielectric spectroscopy measurements of single crystals with different Nd3+ ion concentrations, i.e., when x = 0.0050 or x = 0.0098, and with constant content of Mn2+ ions, i.e., when y = 0.0050. Our magnetic studies have shown that substitution of diamagnetic Ca2+ ions in the CaMoO4 matrix with paramagnetic Nd3+ ones with a content not exceeding 0.02 and having a screened 4f-shell revealed a significant effect of orbital diamagnetism and Van Vleck's paramagnetism. Both single crystals have revealed residual electrical conductivity without an intrinsic region and a change of sign of the Seebeck coefficient at ca. 230 K. Dielectric spectroscopy measurements have shown constant values of relative permittivity (εr ∼ 8) and loss tangent (tan δ ∼ 0.01) both up to 400 K and up to 1 MHz, as well as the Fermi energy (∼0.04 eV) and the Fermi temperature (∼500 K) determined for both crystals from the diffusion component of thermopower. These results suggest the presence of shallow acceptor and donor levels in the studied crystals.

Surface Solar Radiation Compositions Observed from Himawari-8/9 and Fengyun-4 Series

Abstract Surface downward solar radiation compositions (SSRC), including photosynthetically active radiation (PAR), ultraviolet-A (UVA), ultraviolet-B (UVB), and shortwave radiation (SWR), with high spatial–temporal resolutions and precision are essential for applications including solar power, vegetation photosynthesis, and environmental health. In this study, an optimal algorithm was developed to calculate SSRC, including their direct and diffuse components. Key features of the algorithm include combining the radiative transfer model with machine learning techniques, including full consideration of the effects of aerosol types, cloud phases, and gas components. A near-real-time monitoring system was developed based on this algorithm, with SSRC products generated from Himawari-8/9 and Fengyun-4 series data. Validation with ground-based data shows that the accuracy of the SWR and PAR compositions (daily mean RMSEs of 19.7 and 9.2 W m−2, respectively) are significantly better than those of state-of-the-art products from CERES, ERA5, and GLASS. The accuracy of UVA and UVB measurements is comparable with CERES. Characteristics of aerosols, clouds, gases, and their impacts on SSRC are investigated before, during, and post COVID-19; in particular, significant SSRC variations due to the reduction of aerosols and increase of ozone are identified in the Chinese central and eastern areas during that period. The spatial–temporal resolution of data products [up to 0.05° (10 min)−1 for the full-disk region] is one of the most important advantages. Data for the East Asia–Pacific region during 2016–20 is available from the CARE home page (www.slrss.cn/care/sp/pc/).

Estimation of solar resource for vehicle-integrated photovoltaics in urban environments using image-based shade detection.

Vehicle-Integrated Photovoltaics (VIPV) in urban environments face challenges in accurately estimating solar resource due to dynamic shading effects. This research presents a methodology for evaluating VIPV solar resource by analyzing imagery and detecting shade conditions along driving routes. Street image mapping services and obstacle detection algorithms are utilized to determine the shaded or sunny condition of the vehicle at each point. The approach enables the calculation of solar irradiance, considering direct and diffuse components, and identifies energetically optimal driving routes. The methodology provides valuable insights for optimizing MPPT algorithms and assessing VIPV performance in urban settings. It offers a practical tool for sustainable mobility and renewable energy integration.

All-sky surface and top-of-atmosphere shortwave radiation components estimation: Surface shortwave radiation, PAR, UV radiation, and TOA albedo

Surface and top-of-atmosphere (TOA) shortwave radiation components are key parameters in the energy budget of the Earth-atmosphere system, which influence the global climate, ecology, hydrology, etc. However, except for total surface shortwave downward radiation (SWDR), only a few satellite missions consistently release other radiation components such as solar direct/diffuse radiation, photosynthetically active radiation (PAR), ultraviolet radiation-A/B (UVA/UVB), as well as TOA albedo, although they are indispensable for many land and ocean applications. In this study, a unified framework by combining multi-band LUT inversion and classification of the atmospheric condition is proposed, which enables the simultaneous derivation of nine surface and TOA radiation variables and emphasizes the separation of direct and diffuse components. The estimated radiation variables include total and direct components of SWDR, PAR, UVA, UVB, as well as TOA albedo. The proposed method is easy-to-use with only a few inputs and works well with reasonable accuracy. Using Moderate Resolution Imaging Spectroradiometer (MODIS) raw resolution images as test data, the surface radiation variables are validated by 80 global sites from BSRN, SURFRAD, and FLUXNET, and the instantaneous RMSEs (biases) of SWDR, SWDRdir, PAR, PARdiff, and UVB are 103.6 (0.1), 114 (−1.7), 47.8 (6.8), 32.9 (5.7), and 0.14 (0.003) W/m2, respectively, demonstrating comparable or even better accuracy compared with existing products. In particular, the estimated SWDR behaves more accurate than CERES in polar regions. Due to the lack of in-situ measurements, TOA albedo is compared with CERES TOA products and shows good agreement with R2 of 0.9 and RMSE (bias) of 0.055 (−0.003). The unified framework reveals obvious advantages over existing studies in generating almost all physically consistent shortwave components in the same manner with simple inputs, implying the great potentials in globally mapping spatio-temporally continuous multiple components of shortwave radiation with a unified scheme.

Nuclear induction lineshape modeling via hybrid SDE and MD approach.

The temperature dependence of the nuclear free induction decay in the presence of a magnetic-field gradient was found to exhibit motional narrowing in gases upon heating, a behavior that is opposite to that observed in liquids. This has led to the revision of the theoretical framework to include a more detailed description of particle trajectories since decoherence mechanisms depend on histories. In the case of free diffusion and single components, the new model yields the correct temperature trends. The inclusion of boundaries in the current formalism is not straightforward. We present a hybrid SDE-MD (stochastic differential equation - molecular dynamics) approach whereby MD is used to compute an effective viscosity and the latter is fed to the SDE to predict the line shape. The theory is in agreement with the experiments. This two-scale approach, which bridges the gap between short (molecular collisions) and long (nuclear induction) timescales, paves the way for the modeling of complex environments with boundaries, mixtures of chemical species, and intermolecular potentials.

Diffusion Effect on Octogen Coating-Curing Kinetics with Polyurethane Using Infrared Spectroscopy

The kinetic analysis of octogen coating with a polyurethane base containing hydroxyl-terminated polybutadiene (HTPB) was investigated using infrared spectroscopy. The coating process involved a solvent method, where octogen and liquid polyurethane were mixed, the solvent was evaporated, and curing took place at an elevated temperature. The ratio of HTPB to diisocyanate was equimolar. About 200 g octogen was coated with mixture of 2 mL HTPB, 50 mL ethyl acetate, and 0.2 mL TDI in the glass beaker at 30 °C for 1 h. The filtrated ethyl acetate was then evaporated, and the residue was dried in a vacuum oven for 15 min at 30 °C. The resulting film-coated octogen was cast into a KBr pellet and cured in the oven for 7 days at 40 °C, then infrared-analyzed every hour during the curing process. After curing, the shape of the coated octogen particles was analyzed using SEM Initially, the curing process occurred in the solvent system, followed by further curing in the bulk system. The kinetic analysis was performed using a modified diffusion-autocatalytic model, which includes noncatalytic, autocatalytic, and diffusion components. This model was compared with others during the bulk reaction and proved to be effective in correcting errors, particularly in the gel time region. Thermodynamic parameters were evaluated using the Arrhenius and Eyring equations. The reaction rate was initially controlled by chemical reactivity, but after the gel time, diffusion became the controlling factor. In the HTPB-TDI system, both the noncatalytic and autocatalytic parts decreased with increasing temperature, while diffusivity increased. It is worth noting that diffusivity is temperature-dependent. Different di-isocyanates, namely toluene diisocyanate (TDI), iso-phorone diisocyanate (IPDI), and hexamethylene diisocyanate (HMDI), were studied, revealing that HMDI exhibited higher reactivity than TDI and IPDI. The catalyst effect on reaction rate of the HTPB-TDI system was investigated. The addition of catalysts (0.1%) to the HTPB-TDI system decreased their activation energy in the order DBTL > FeAA > TPB. Catalysts did not change their diffusivity.

Three‐dimensional multiscale assembly of phyllosilicates, organics, and carbonates in small Ryugu fragments

AbstractWe report μm‐scale nondestructive infrared (IR) hyperspectral results (IR computed tomography, IR‐CT) in 3‐D and IR surface imaging, IR‐S) in 2‐D, at SOLEIL) combined with X‐ray nano‐computed tomography analyses (at SPring‐8) performed on eight small Ryugu fragments extracted from mm‐sized grains coming both from touchdown first and second sites. We describe the multiscale assembly of phyllosilicates, carbonates, sulfides, oxides, and organics. Two types of silicates, as well as diverse kinds of organic matter, were detected inside Ryugu material. Their spatial correlations are described to discuss the role of the mineralogical microenvironments in the formation/evolution of organic matter. In particular, we have shown that there is a redistribution of the organic matter diffuse component during aqueous alteration on the parent body, with a preferential circulation among fine‐grained phyllosilicates.