Leaky Structures Research Articles

Endothelial c-Src mediates neovascular tuft formation in Oxygen-Induced Retinopathy

Vascular retinopathy, characterised by abnormal blood vessel growth in the retina, frequently results in vision impairment or loss. Neovascular tufts, a distinctive pathological feature of this condition, are highly leaky blood vessel structures, exacerbating secondary complications. Despite their clinical significance, the mechanisms underlying tuft development are not fully elucidated, posing challenges for effective management and treatment of vascular retinopathy. This study investigates the role of c-Src in neovascular tuft formation. Although c-Src has been acknowledged as a pivotal regulator in developmental angiogenesis within the retinal vasculature, its specific role in governing pathological retinal angiogenesis remains to be fully understood.The Oxygen-Induced Retinopathy (OIR) model was used for neovascular tufts formation in both Cre-mediated vascular specific c-Src knockout mice and wildtype littermates. High-resolution imaging and analysis of isolated retinas was conducted. c-Src depletion demonstrated a significant reduction in neovascular tufts within the OIR model. This decrease in tuft formation was observed independently of any alterations in cell death, cell proliferation or cell adhesion and the absence of c-Src did not impact tuft pericyte coverage and junctional morphology. These findings underscore the critical role of c-Src in the pathogenesis of neovascular tufts in vascular retinopathy. Understanding the molecular mechanisms involving c-Src may offer valuable insights for the development of targeted therapies aimed at mitigating vision-threatening complications associated with retinopathy.

Analytical formulation of spatiotemporal modulated graphene-based waveguides using Floquet-Bloch theory

In this work, an analytical model to study graphene-based spatiotemporal modulated structures is developed and verified through comparison with full wave numerical simulations. Graphene is an ideal material for realizing spatiotemporal modulated structures at high frequencies of THz and optics. In this analysis, the electromagnetic response of studied structures is expressed in terms of weighted Floquet-Bloch modes supported by the structure, while graphene is modeled by a spatiotemporal modulated surface current that imposes certain boundary conditions on the modes. The developed analytical technique is a comprehensive tool and can be used for accurate modeling of different kinds of spatiotemporal devices including lossy, guided, and leaky wave structures. To demonstrate the accuracy of the model, two plasmonic waveguides with space and time modulated graphene conductivity are analyzed and their interband and intraband transition between modes are thoroughly investigated. Using the developed analytical model, spatiotemporal modulation phenomena such as mode conversion, wave amplification and nonreciprocal response are explored and discussed for the studied structures.

Synthesizing multi-frame high-resolution fluorescein angiography images from retinal fundus images using generative adversarial networks

BackgroundFundus fluorescein angiography (FA) can be used to diagnose fundus diseases by observing dynamic fluorescein changes that reflect vascular circulation in the fundus. As FA may pose a risk to patients, generative adversarial networks have been used to convert retinal fundus images into fluorescein angiography images. However, the available methods focus on generating FA images of a single phase, and the resolution of the generated FA images is low, being unsuitable for accurately diagnosing fundus diseases.MethodsWe propose a network that generates multi-frame high-resolution FA images. This network consists of a low-resolution GAN (LrGAN) and a high-resolution GAN (HrGAN), where LrGAN generates low-resolution and full-size FA images with global intensity information, HrGAN takes the FA images generated by LrGAN as input to generate multi-frame high-resolution FA patches. Finally, the FA patches are merged into full-size FA images.ResultsOur approach combines supervised and unsupervised learning methods and achieves better quantitative and qualitative results than using either method alone. Structural similarity (SSIM), normalized cross-correlation (NCC) and peak signal-to-noise ratio (PSNR) were used as quantitative metrics to evaluate the performance of the proposed method. The experimental results show that our method achieves better quantitative results with structural similarity of 0.7126, normalized cross-correlation of 0.6799, and peak signal-to-noise ratio of 15.77. In addition, ablation experiments also demonstrate that using a shared encoder and residual channel attention module in HrGAN is helpful for the generation of high-resolution images.ConclusionsOverall, our method has higher performance for generating retinal vessel details and leaky structures in multiple critical phases, showing a promising clinical diagnostic value.

Co/N-codoped carbon nanotube hollow polyhedron hybrid derived from salt-encapsulated core-shell ZIF-8@ZIF-67 for efficient oxygen reduction reaction

The rational design and construction of non-precious metal-based electrocatalysts with high activity and stability toward oxygen reduction reactions (ORR) are essential but challenging. In this work, a novel hybrid nanoporous structure of Co nanoparticles uniformly embedded in hollow porous carbon doped with nitrogen (CoNHPC) was constructed by a melt-evaporation-pyrolysis method, in which NaCl is utilized as an auxiliary template. The introduction to NaCl in this process served as the confining template to prevent nitrogen loss and promote graphitization, and the intercalating agent to form a mesoporous product. Due to the composite hierarchical porous structure, higher graphitization degree, and desirable nitrogen bonding type, the as-prepared CoNHPC-920 presents outstanding ORR electrocatalytic activity in terms of a half-wave potential of 0.87 V (vs. RHE) and onset potential of 0.97 V (vs. RHE). The composite material also shows higher selectivity and outstanding durability with most transition metal porous carbon materials reported. The strategy proposed in this study may provide ideas about metal nitrogen-carbon type catalysts enriched with carbon nanotubes and bare leaky hollow structures of the construction of advanced ORR electrocatalysts, opening up a new pathway.

Research of actual information on well casing using machine learning and neural networks

In domestic and world practice, despite the measures applied and developed to improve the quality of well casing, there is a problem of leaky structures in almost 50 % of completed wells. The study of actual data using classical methods of statistical analysis (regression and variance analyses) doesn't allow us to model the process with sufficient accuracy that requires the development of a new approach to the study of the attachment process. It is proposed to use the methods of machine learning and neural network modeling to identify the most important parameters and their synergistic impact on the target variables that affect the quality of well casing. The formulas necessary for translating the numerical values of the results of acoustic and gamma-gamma cementometry into categorical variables to improve the quality of probabilistic models are determined. A database consisting of 93 parameters for 934 wells of fields located in Western Siberia has been formed. The analysis of fastening of production columns of horizontal wells of four stratigraphic arches is carried out, the most weighty variables and regularities of their influence on target indicators are established. Recommendations are formulated to improve the quality of well casing by correcting the effects of acoustic and gamma-gamma logging on the results.

Natural flood management, lag time and catchment scale: Results from an empirical nested catchment study

AbstractNatural flood management (NFM) techniques attract much interest in flood risk management science, not least because their effectiveness remains subject to considerable uncertainty, particularly at larger catchment and event scales. This derives from a paucity of empirical studies which can offer either longitudinal or comparison data sets in which changes can be observed. The Eddleston catchment study, with 13 stream gauges operated continuously over 9 years, is based on both longitudinal and comparison data sets. Two years of baseline monitoring have been followed by 7 years of further monitoring after a range of NFM interventions across the 69 km2catchment. This study has examined changes in lag as an index of hydrological response which avoids dependence on potentially significant uncertainties in flow data. Headwater catchments up to 26 km2showed significant delays in lag of 2.6–7.3 hr in catchments provided with leaky wood structures, on‐line ponds and riparian planting, while larger catchments downstream and those treated with riparian planting alone did not. Two control catchments failed to show any such changes. The findings provide important evidence of the catchment scale at which NFM can be effective and suggest that effects may increase with event magnitude.

Kramers-Kronig relations for magnetoinductive waves

Kramers-Kronig relations for propagating modes are a fundamental property of many but not all structures supporting wave propagation. While Kramers-Kronig relations for a transfer function of a causal system are always satisfied, it was discovered in the past that Kramers-Kronig relations for individual modes of a system may fail, e.g., in leaky structures. Our aim in this paper is to scrutinize whether magnetoinductive waves propagating in discrete metamaterial structures by virtue of interelement coupling satisfy Kramers-Kronig relations. Starting with the dispersion relations of magnetoinductive waves in the nearest-neighbor approximation we investigated the real and imaginary parts of two complex functions: the propagation coefficient and the transfer function. In order to show that the real and imaginary parts of these functions are related to each other by the Kramers-Kronig relations we had to modify the functions by deducting from them the values of the functions at infinite frequencies. It was shown that these modified functions and their Kramers-Kronig pairs perfectly coincided. The much more complicated case of magnetoinductive wave propagation with long-range coupling assumed was also investigated. The mode structure was derived for interactions up to the third neighbor. It was shown that the Kramers-Kronig relations are not applicable to the individual modes, but are valid for the transfer functions of the waveguide after solving the excitation problem and taking all the modes into account. Our method can be applied to practically relevant cases enabling rapid evaluation of transfer functions, e.g., in metamaterials used for wireless power transfer.

NIR-II-Excited Intravital Two-Photon Microscopy Distinguishes Deep Cerebral and Tumor Vasculatures with an Ultrabright NIR-I AIE Luminogen.

Intravital fluorescence imaging of vasculature morphology and dynamics in the brain and in tumors with large penetration depth and high signal-to-background ratio (SBR) is highly desirable for the study and theranostics of vascular-related diseases and cancers. Herein, a highly bright fluorophore (BTPETQ) with long-wavelength absorption and aggregation-induced near-infrared (NIR) emission (maximum at ≈700 nm) is designed for intravital two-photon fluorescence (2PF) imaging of a mouse brain and tumor vasculatures under NIR-II light (1200 nm) excitation. BTPETQ dots fabricated via nanoprecipitation show uniform size of around 42 nm and a high quantum yield of 19 ± 1% in aqueous media. The 2PF imaging of the mouse brain vasculatures labeled by BTPETQ dots reveals a 3D blood vessel network with an ultradeep depth of 924 µm. In addition, BTPETQ dots show enhanced 2PF in tumor vasculatures due to their unique leaky structures, which facilitates the differentiation of normal blood vessels from tumor vessels with high SBR in deep tumor tissues. Moreover, the extravasation and accumulation of BTPETQ dots in deep tumor (more than 900 µm) is visualized under NIR-II excitation. This study highlights the importance of developing NIR-II light excitable efficient NIR fluorophores for in vivo deep tissue and high contrast tumor imaging.

Programmed Nanoparticle-Loaded Nanoparticles for Deep-Penetrating 3D Cancer Therapy.

Tumors are 3D, composed of cellular agglomerations and blood vessels. Therapies involving nanoparticles utilize specific accumulations due to the leaky vascular structures. However, systemically injected nanoparticles are mostly uptaken by cells located on the surfaces of cancer tissues, lacking deep penetration into the core cancer regions. Herein, an unprecedented strategy, described as injecting "nanoparticle-loaded nanoparticles" to address the long-lasting problem is reported for effective surface-to-core drug delivery in entire 3D tumors. The "nanoparticle-loaded nanoparticle" is a silica nanoparticle (≈150 nm) with well-developed, interconnected channels (diameter of ≈30 nm), in which small gold nanoparticles (AuNPs) (≈15 nm) with programmable DNA are located. The nanoparticle (AuNPs)-loaded nanoparticles (silica): (1) can accumulate in tumors through leaky vascular structures by protecting the inner therapeutic AuNPs during blood circulation, and then (2) allow diffusion of the AuNPs for penetration into the entire surface-to-core tumor tissues, and finally (3) release a drug triggered by cancer-characteristic pH gradients. The hierarchical "nanoparticle-loaded nanoparticle" can be a rational design for cancer therapies because the outer large nanoparticles are effective in blood circulation and in protection of the therapeutic nanoparticles inside, allowing the loaded small nanoparticles to penetrate deeply into 3D tumors with anticancer drugs.

Spoof plasmon radiation using sinusoidally modulated corrugated reactance surfaces.

In this paper we theoretically investigate the feasibility of creating leaky wave antennas capable of converting spoof plasmons to radiating modes. Spoof plasmons are surface waves excited along metallic corrugated surfaces and they are considered the microwave and THz equivalent of optical surface plasmon polaritons. Given that a corrugated surface is essentially a reactance surface, the proposed design methodology relies on engineering a corrugated surface so that it exhibits a sinusoidally modulated reactance profile. Through such non-uniform periodic reactance surfaces, guided surface waves can efficiently couple into free-space radiating modes. This requires the development of a realistic methodology that effectively maps the necessary sinusoidal reactance variation to a sinusoidal variation corresponding to the depth of the grooves. Both planar and cylindrical corrugated surfaces are examined and it is numerically demonstrated that the corresponding sinusoidally modulated leaky wave structures can very efficiently convert guided spoof plasmons to radiating modes.

Generation of heralded entanglement between distant hole spins

Quantum entanglement emerges naturally in interacting quantum systems and plays a central role in quantum information processing. Remarkably, it is possible to generate entanglement even in the absence of direct interactions: provided that which path information is erased, weak spin-state dependent light scattering can be used to project two distant spins onto a maximally entangled state upon detection of a single photon. Even though this approach is necessarily probabilistic, successful generation of entanglement is heralded by the photon detection event. Here, we demonstrate heralded quantum entanglement of two quantum dot heavy-hole spins separated by 5 meters using single-photon interference. Thanks to the long coherence time of hole spins and the efficient spin-photon interface provided by self-assembled quantum dots embedded in leaky microcavity structures, we generate 2300 entangled spin pairs per second, which represents an improvement approaching three orders of magnitude as compared to prior experiments. Delayed two-photon interference scheme we developed allows for efficient verification of quantum correlations. Our results lay the groundwork for the realization of quantum networks in semiconductor nanostructures. Combined with schemes for transferring quantum information to a long-lived memory qubit, fast entanglement generation we demonstrate could also impact quantum repeater architectures.

The role of seal integrity in the Vlaming Sub-basin (Perth Basin) for preservation of hydrocarbon accumulations

SUMMARY The offshore Vlaming Sub-basin, located in the southern part of the Perth Basin, is a Mesozoic depocentre estimated to contain over 12 km of sediments. It has several potential source rock intervals, good reservoir and seal pairs and an active petroleum system. The reasons for a lack of exploration success in this basin have been re-assessed by analysing fault reactivation and signs of hydrocarbon seepage. A recently completed study integrated structural mapping with analysis of fluid inclusion results. New data and interpretations show that a number of synrift faults with signs of reactivation in seismic data also have Fluid Inclusion Stratigraphy (FIS) anomalies above the regional seal. Many previously identified plays rely on the post-rift South Perth Shale for a seal. Our analysis suggests that many faults were reactivated after the deposition of the South Perth Shale, with some showing signs of present-day reactivation. Reactivated faults provided migration pathways for generated hydrocarbons; therefore, no accumulations were formed at these locations. The study provides insight into the location of leaky structures and areas with potentially valid plays in the Vlaming Sub-basin.

Excitation of Complex Modes of Periodic Structures Using Inhomogeneous Plane Wave Scattering in Fast and Slow Wave Regions

Periodic metamaterial unit cells are analyzed by using inhomogeneous plane wave scattering. The complex modes of the unit cell are derived using either the poles or the zeroes of the complex reflection coefficient of the fundamental Floquet mode. The required reflection coefficients are computed by a doubly periodic finite element boundary integral technique. The search for the eigenvalues is accelerated by the nonlinear Nelder-Mead method. Usually, pairs of eigenvalues are observed, which can be both, real or conjugate complex. Also, the eigenvalues correspond either to proper or improper modes. By selecting the proper or the improper modes during field computation, the other type of modes is removed from the observed response and, instead, zeroes are found in the reflection coefficient. This can explain the absorption behavior of single-sided open periodic leaky structures by investigating their reflection coefficient with the proposed inhomogeneous plane wave excitation approach. The obtained results for various single-sided open periodic unit cells are in good agreement with the results of other methods, where in the presented excitation based method there is no need to solve any dispersion equation in the complex plane.

Nanographene Oxide–Hyaluronic Acid Conjugate for Photothermal Ablation Therapy of Skin Cancer

Melanoma skin cancer is one of the most dangerous skin cancers and the main cause of skin-cancer-related mortality. Hyaluronic acid (HA) has been used as an effective transdermal delivery carrier of chemical drugs and biopharmaceuticals. In this work, a nanographene oxide-HA conjugate (NGO-HA) was synthesized for photothermal ablation therapy of melanoma skin cancer using a near-infrared (NIR) laser. Confocal microscopy and ex vivo bioimaging clearly visualized the remarkable transdermal delivery of NGO-HA to tumor tissues in the skin of mice, which might be ascribed to highly expressed HA receptors and relatively leaky structures around tumor tissues, enabling the enhanced permeation and retention of nanoparticles. The NIR irradiation resulted in complete ablation of tumor tissues with no recurrence of tumorigenesis. The antitumor effect was confirmed by ELISA for caspase-3 activity and histological and immunohistochemical analyses with TUNEL assay for tumor apoptosis. Taken together, we could confirm the feasibility of transdermal NGO-HA for photothermal ablation therapy of melanoma skin cancers.

Core-Confined Beam Propagation Method for Guiding and Leaky Structures

We propose a beam propagation method variant, which only requires the computational grid to span the core region of a waveguiding structure. Optical fields outside are accounted for through semitransparent boundary conditions. The method is fast, simple to implement, and accurate over a wide range of wavelengths. It is applicable to both guiding and leaky structures, with sufficiently strong contrast between refractive indices in the core, substrate, and cladding.

Evidential network-based extension of Leaky Noisy-OR structure for supporting risks analyses

Bayesian Networks (BN) are used in risks analysis because their capacities allow supporting complex system modeling. Nevertheless, to achieve some modeling, one BN issue is still the effort required for quantification even if some solutions are addressing the use of logical structures like OR, AND, Noisy-OR, Leaky Noisy-OR, etc. These structures are useful to represent different uncertainties but they do not allow taking into account uncertainty on their parameters, logically present in risks analysis. To face this challenge, this paper aims at proposing imprecise extensions of the Leaky Noisy-OR structures and a solution to implement these imprecise structures by using Evidential networks.

Fundamental Electromagnetic Properties of Twisted Periodic Arrays

Linear periodic arrays of elements sequentially rotated about the array's axis display interesting polarization properties. These “twisted” arrays, characterized by both discrete and helical periodicities, exhibit features of periodic gratings and bulk chiral media. For arrays with small periodicities, in which the zeroth diffraction (Floquet) mode dominates, two independent, transverse traveling wave modes are identified. One of these mode types is a guided wave that remains bound to the array, while the other is a leaky (radiating) wave mode. The electric fields characterizing each mode consist of two circularly polarized waves with distinct phase velocities. For larger periodicities, higher diffraction orders of these two modes may radiate. The coupling between different modes may result in stopbands of several types but the broadside stopband typical of leaky wave structures is eliminated. A finite twisted array is simulated to verify the predicted properties, and to show that the two transverse modes may be excited by circularly polarized sources with opposite handedness. Results are demonstrated for arrays of plasmonic particles in the optical regime and arrays of half-wave dipoles in the microwave regime. Twisted arrays can find uses in various microwave and optical applications, such as frequency and polarization sensitive waveguides, couplers, filters, and antennas.

Nanomaterials for cancer therapy and imaging.

A variety of organic and inorganic nanomaterials with dimensions below several hundred nanometers are recently emerging as promising tools for cancer therapeutic and diagnostic applications due to their unique characteristics of passive tumor targeting. A wide range of nanomedicine platforms such as polymeric micelles, liposomes, dendrimers, and polymeric nanoparticles have been extensively explored for targeted delivery of anti-cancer agents, because they can accumulate in the solid tumor site via leaky tumor vascular structures, thereby selectively delivering therapeutic payloads into the desired tumor tissue. In recent years, nanoscale delivery vehicles for small interfering RNA (siRNA) have been also developed as effective therapeutic approaches to treat cancer. Furthermore, rationally designed multi-functional surface modification of these nanomaterials with cancer targeting moieties, protective polymers, and imaging agents can lead to fabrication versatile theragnostic nanosystems that allow simultaneous cancer therapy and diagnosis. This review highlights the current state and future prospects of diverse biomedical nanomaterials for cancer therapy and imaging.

Household Disrepair and the Mental Health of Low-Income Urban Women

We employ longitudinal survey data from the Welfare, Children, and Families project (1999, 2001) to examine the effects of household disrepair (e.g., living with leaky structures, busted plumbing, broken windows, and pests) on psychological distress among low-income urban women with children. Building on previous research, we adjust for related housing concepts, neighborhood disorder, financial hardship, and a host of relevant background factors. We also formally test the mediating influences of social support and self-esteem. Our cross-sectional analysis indicated that household disrepair is positively associated with recent symptoms of psychological distress. Our longitudinal change score analysis demonstrates two important patterns. First, women living with household disrepair at baseline are not necessarily vulnerable to increases in symptoms of psychological distress over the 2-year study period. Second, women who report an increase in disrepair over the study period are also likely to report a concurrent increase in symptoms of distress. Although social support and self-esteem favor mental health in our cross-sectional and longitudinal analyses, these psychosocial resources fail to mediate or explain the association between disrepair and distress.

Effect of perfectly matched layer reflection coefficient on modal analysis of leaky waveguide modes

The reflection coefficient is one important parameter of the perfectly matched layer (PML). Here we investigate its effect on the modal analysis of leaky waveguide modes by examining three different leaky waveguide structures, i.e., the holey fiber, the air-core terahertz pipe waveguide, and the gain-guided and index-antiguided slab waveguide. Numerical results reveal that the typical values 10(-8) ~10(-12) are inadequate for obtaining the imaginary part of the complex propagation constant, and the suggested reflection coefficient would be much smaller, for example, 10(-50) or 10(-100). With such a small coefficient, both the computational window size and the PML thickness can be significantly reduced without loss of stability. Moreover, in some cases, the modal field profiles can only be accurately obtained with such a small coefficient.