We present a framework for exact analytical computation of bandlimited Slepian functions for Hierarchical Equal Area iso-Latitude Pixelization (HEALPix) scheme on the sphere. Slepian functions are ...bandlimited eigenfunctions obtained by solving the spatial-spectral concentration problem on the sphere. Utilizing rotational symmetries between the HEALPix pixels, we employ Wigner-<inline-formula><tex-math notation="LaTeX">D</tex-math></inline-formula> functions to efficiently compute the bandlimited Slepian functions at different resolutions of the HEALPix partitioning scheme. We present convergence criteria for the infinite series expansions involved in the analytical expressions, analyze the complexity of computing bandlimited Slepian functions and construct an overcomplete multiscale dictionary of bandlimited Slepian functions on the sphere. We show that the dictionary spans the space of bandlimited functions, which are well-optimally (energy) concentrated within a region on the sphere, and that its elements exhibit small mutual coherence. As a demonstration of the utility of the dictionary, we present localized representation of a bandlimited Earth topography map over the South American continent, and conduct performance comparison with the representations obtained from the Slepian functions for a rotationally symmetric region, centered on South America, and for the South American coastal region, extracted from the coastlines data available in MATLAB .
We present spatial-Slepian transform (SST) for the joint spatial-Slepian domain representation of signals on the sphere to support localized signal analysis. We employ well-optimally concentrated ...Slepian functions, which are obtained as a solution of the Slepian spatial-spectral concentration problem of finding bandlimited and spatially optimally concentrated functions on the sphere, to formulate the proposed transform. Due to optimal energy concentration of Slepian functions in the spatial domain, the proposed spatial-Slepian transform allows us to probe spatially localized content of the signal. Furthermore, we present an inverse transform to recover the signal from its spatial-Slepian coefficients, formulate an algorithm for fast computation of SST, and carry out computational complexity analysis. We compute the spatial variance of spatial-Slepian coefficients and conduct experiments to show that spatial-Slepian coefficients have better spatial localization than scale-discretized wavelet coefficients. We present the formulation of SST for zonal Slepian functions, which are spatially optimally concentrated in the axisymmetric polar cap region, and provide an illustration using a bandlimited Earth topography map. To demonstrate the utility of the proposed transform, we carry out localized variation analysis, in which we employ SST to detect hidden localized variations in the signal. We illustrate, through a toy example, that spatial-Slepian transform yields a much better estimate of the underlying region of hidden localized variations than scale-discretized wavelet transform.
We develop a framework for generalized linear transformations of the joint spatial-Slepian domain representation of signals on the sphere. Such a representation is enabled by the spatial-Slepian ...transform on the sphere. We formulate a least-square signal estimation framework for reconstruction of the spherical signal from the modified (transformed) spatial-Slepian representation specified by the spatial-Slepian transformation kernel. We specialize the form of the kernel to present analytical expressions for the multiplicative and convolutive transformations, and use the latter to present illustrations on a Mars topography map.
Sorbent pads and films have been commonly used for environmental remediation purposes, but designing their internal structure to optimize access to the entire volume while ensuring ...cost-effectiveness, ease of fabrication, sufficient strength, and reusability remains challenging. Herein, we report a trimodal sorbent film from recycled polypropylene (PP) with micropores, macro-voids, and sponge-like 3D cavities, developed through selective dissolution, thermally induced phase separation, and annealing. The sorbent has hundreds of cavities per cm2 that are capable of swelling up to twenty-five times its thickness, allowing for super-fast saturation kinetics (within 30 s) and maximum oil sorption (97 g/g). The sorption mechanism follows a pseudo-second-order kinetic model. Moreover, the sorbent is easily compressible, and its structure is retained during oil sorption, desorption, and resorption, resulting in 96.5% reuse efficiency. The oil recovery process involves manually squeezing the film, making the cleanup process efficient with no chemical treatment required. The sorbent film possesses high porosity for effective sorption with sufficient tensile strength for practical applications. Our integrated technique results in a strengthened porous polymeric structure that can be tailored according to end-use applications. This study provides a sustainable solution for waste management that offers versatility in its functionality.
Autophagy is a preserved cytoplasmic self‐degradation process and endorses recycling of intracellular constituents into bioenergetics for the controlling of cellular homeostasis. Functional autophagy ...process is essential in eliminating cytoplasmic waste components and helps in the recycling of some of its constituents. Studies have revealed that neurodegenerative disorders may be caused by mutations in autophagy‐related genes and alterations of autophagic flux. Alzheimer’s disease (AD) is an irrevocable deleterious neurodegenerative disorder characterized by the formation of senile plaques and neurofibrillary tangles (NFTs) in the hippocampus and cortex. In the central nervous system of healthy people, there is no accretion of amyloid β (Aβ) peptides due to the balance between generation and degradation of Aβ. However, for AD patients, the generation of Aβ peptides is higher than lysis that causes accretion of Aβ. Likewise, the maturation of autophagolysosomes and inhibition of their retrograde transport creates favorable conditions for Aβ accumulation. Furthermore, increasing mammalian target of rapamycin (mTOR) signaling raises tau levels as well as phosphorylation. Alteration of mTOR activity occurs in the early stage of AD. In addition, copious evidence links autophagic/lysosomal dysfunction in AD. Compromised mitophagy is also accountable for dysfunctional mitochondria that raises Alzheimer’s pathology. Therefore, autophagic dysfunction might lead to the deposit of atypical proteins in the AD brain and manipulation of autophagy could be considered as an emerging therapeutic target. This review highlights the critical linkage of autophagy in the pathogenesis of AD, and avows a new insight to search for therapeutic target for blocking Alzheimer’s pathogenesis.
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Controlled autophagy is important for cellular homeostasis.
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Dysfunctional autophagic mechanisms are implicated in many pathological states especially neurodegeneration.
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Potential synthetic and natural compounds stimulate autophagy as a protective mechanism to abate Alzheimer’s pathogenesis.
Neither the bis nor the tetrakis-pyridyl system, but a simple monopyridyl-linked anthracenyl π-conjugate is established as a reversible protonation/deprotonation stimuli-responsive solid material ...with 129 nm red-shift in the fluorescence. This feature is applied to develop the fluorophore coated paper sheet to be used in security writings with an acid-pen and a base-eraser.
9-arylated acridine-based derivatives (AUPAO &AUEA) with high visibility, fluorescence, and excellent lightfastness were synthesized in good yield. The molecules were characterized by 1H NMR, 13C ...NMR, HRMS and further investigated for photophysical properties. Initially, absorption and emission studies were carried out in wide-ranging polarity solvents to choose a solvent of interest for further investigations. Concentration-dependent studies were carried out in ethanol to determine an optimized concentration to study lightfastness studies. These molecules showed excellent lightfastness properties in solution form when compared to commercially available acridine orange. pH-dependent studies were also carried out to observe the behavior of cationic dyes in a wide range of pH to optimize pH for dyeing. The presence of extended conjugation at the 9th position and additional four methoxy groups resulted in highly fluorescent dyes with excellent quantum yield. The steric interactions, higher twist, and unrestricted rotation of the conjugation pathway between the aromatic ring at the 9th position and the acridine core decreased the transition probability and energy transfer that helped improve the lightfastness. The introduction of a hydroxyl group in AUEA increased the solubility and helped in controlled dispersion while dyeing. Further, they were dyed on modacrylic fabric as high visibility fluorophores, and later the color coordinates, color strengths were measured.
•9-arylated acridine-based high visible fluorophores (AUPAO &AUEA) were synthesized in good yields.•These molecules showed a high molar absorption coefficient and fluorescence with more quantum yield.•These molecules are promising candidates with improved lightfastness when compared to acridine orange (AO).•The presence of aromatic ring at 9th position and four methoxy groups helped in increased fluorescence and quantum yield.•The presence of the hydroxyl group gave AUEA an advantage over AUPAO in solubility and diverse pH conditions.•These molecules also demonstrated good dyeing properties on modacrylic fibers.
Layered double hydroxide (LDH) with characteristic two‐dimensional structure and positive layer charge has attracted attention in a wide range of applications in recent years. Although LDH with a ...layer‐by‐layer structure has high applicability as a catalyst, adsorbent, drug reservoir, and so on, it has been suggested that the single‐layered LDH nanosheets not only enhance the performance but also expand the application in electrocatalyst, batteries, and supercapacitors due to the increased active sites in nanosheets. In this review, we introduced state of the art in the synthesis of LDH nanosheets in terms of synthesis approaches, mechanisms, and properties of thus obtained LDH nanosheets. The synthesis approaches are primarily categorized into two parts, namely, top‐down synthesis to delaminate bulk LDH and bottom‐up synthesis to obtain single‐layer LDH in limited space. In the first section, the exfoliation of LDH, which was realized by weakening the layer‐by‐layer stacking and by increasing the basal distance, was summarized mainly based on the swelling mechanism. In the second section, the bottom‐up syntheses of LDH nanosheets through controlled crystal growth in confined space or restricted synthetic conditions are introduced.
Nanosheets of layered double hydroxides (LDH) can be either prepared by top‐down exfoliation or bottom‐up synthesis under restricted crystal growth condition. For exfoliation, swelling with solvent species can be facilitated with an appropriate intercalation; bottom‐up synthesis utilized confined reaction spaces to limit the layer stacking along c‐axis.
Clouds, together with their shadows, usually occlude ground-cover features in optical remote sensing images. This hinders the utilization of these images for a range of applications such as earth ...observation, land-cover classification and urban planning. In this work, we propose a deep unfolded and prior-aided robust principal component analysis (DUPA-RPCA) network for removing clouds and recovering ground-cover information in multi-temporal satellite images. We model these cloud-contaminated images as a sum of low rank and sparse elements and then unfold an iterative RPCA algorithm that has been designed for reweighted <inline-formula><tex-math notation="LaTeX">\ell _{1}</tex-math></inline-formula> minimization. As a result, the activation function in DUPA-RPCA adapts for every input at each layer of the network. Our experimental results on both Landsat and Sentinel images indicate that our method gives better accuracy and efficiency when compared with existing state of the art methods.
ABSTRACTThe study was designed to develop functional cucumber and pomegranate based ready-to-serve (RTS) drink as thirst quencher. To boost antioxidant activity and to add natural preservation to the ...drink, microwave-assisted extracts of herbs and spices; mint, lemongrass, ginger, cinnamon were incorporated either individually or collective, at an equivalent dose of 2% for comparison. In this regard, ginger extract incorporated drink maintained its storage quality owing to highest free radical scavenging potential (49 to 67%) in relevance to highest polyphenol and flavonoid contents (1203 ± 64 mg GAE/L and 178 ± 8 mg TE/L, respectively). Whereas, ascorbic acid was maximally recorded in lemongrass-based drink 22 ± 1 mg/100 mL. During 30 days storage under refrigeration, significant decrease was recorded in pH of the RTS drink along with considerable increase in acidity and browning index however, total soluble solids demonstrated non-significant pattern. Sedimentation showed an inclining trend (p˂.05) with progression in storage but comparatively less sedimentation was attributed to lemongrass incorporated drink followed by cinnamon containing drink. Turbidity also indicated significant changes but showed inverse pattern with respect to sedimentation. Additionally, ginger-based drink expressed considerably low total plate count as 2.3 ± .1 log CFU/mL with nil yeast and mold growth by all the extracts throughout storage. Further, ginger portrayed highest rate for odor, taste and consistency though, mixed herbs and spices based drink attained the best color score. Conclusively, ginger-based drink portrayed maximum antioxidant and antimicrobial properties.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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