Color Histogram Diffusion for Image Enhancement

Various color histogram equalization (CHE) methods have been proposed to extend grayscale histogram equalization (GHE) for color images. In this paper a new method called histogram diffusion that extends the GHE method to arbitrary dimensions is proposed. Ranges in a histogram are specified as overlapping bars of uniform heights and variable widths which are proportional to their frequencies. This diagram is called the vistogram. As an alternative approach to GHE, the squared error of the vistogram from the uniform distribution is minimized. Each bar in the vistogram is approximated by a Gaussian function. Gaussian particles in the vistoram diffuse as a nonlinear autonomous system of ordinary differential equations. CHE results of color images showed that the approach is effective

Lunar Terrain and Albedo Reconstruction from Apollo Imagery

Generating accurate three dimensional planetary models and albedo maps is becoming increasingly more important as NASA plans more robotics missions to the Moon in the coming years. This paper describes a novel approach for separation of topography and albedo maps from orbital Lunar images. Our method uses an optimal Bayesian correlator to refine the stereo disparity map and generate a set of accurate digital elevation models (DEM). The albedo maps are obtained using a multi-image formation model that relies on the derived DEMs and the Lunar- Lambert reflectance model. The method is demonstrated on a set of high resolution scanned images from the Apollo era missions

Photometric Lunar Surface Reconstruction

Accurate photometric reconstruction of the Lunar surface is important in the context of upcoming NASA robotic missions to the Moon and in giving a more accurate understanding of the Lunar soil composition. This paper describes a novel approach for joint estimation of Lunar albedo, camera exposure time, and photometric parameters that utilizes an accurate Lunar-Lambertian reflectance model and previously derived Lunar topography of the area visualized during the Apollo missions. The method introduced here is used in creating the largest Lunar albedo map (16% of the Lunar surface) at the resolution of 10 meters/pixel

Drug delivery by a self-assembled DNA tetrahedron for overcoming drug resistance in breast cancer cells

A DNA tetrahedron is employed for efficient delivery of doxorubicin into drug-resistant breast cancer cells. The drug delivered with the DNA nanoconstruct is considerably cytotoxic, whereas free doxorubicin is virtually non-cytotoxic for the drug-resistant cells. Thus, the DNA tetrahedron, made of the inherently natural and biocompatible material, can be a good candidate for the drug carrier to overcome MDR in cancer cells.close11

Covalent functionalization based heteroatom doped graphene nanosheet as a metal-free electrocatalyst for oxygen reduction reaction

Oxygen reduction reaction (ORR) is an important reaction in energy conversion systems such as fuel cells and metal-air batteries. Carbon nanomaterials doped with heteroatoms are highly attractive materials for use as electrocatalysts by virtue of their excellent electrocatalytic activity, high conductivity, and large surface area. This study reports the synthesis of highly efficient electrocatalysts based on heteroatom-doped graphene nanosheets prepared through covalent functionalization using various small organic molecules and a subsequent thermal treatment. A series of nitrogen-doped reduced graphene oxide (NRGOn) nanosheets exhibited varying degrees and configurations of nitrogen atoms within the graphitic framework depending on the type of precursors used. On the basis of the rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) experiments, NRGO3, with a high degree of pyridinic-N content, displayed the desired one-step, quasi-four-electron transfer pathway during ORR, similar to commercial Pt/C. We also demonstrated the potential of covalent functionalization of sulfur and boron-doped graphene nanosheets.close4

Mussel-inspired nitrogen-doped graphene nanosheet supported manganese oxide nanowires as highly efficient electrocatalysts for oxygen reduction reaction

Electrocatalysts for oxygen reduction reaction (ORR) play a vital role in determining the performance of fuel cells and metal-air batteries. Carbon nanomaterials doped with heteroatoms are highly attractive by virtue of their excellent electrocatalytic activity, high conductivity and large surface area. This study reports the synthesis of a highly efficient electrocatalyst based on nitrogen-doped (N-doped) graphene nanosheets (NG) using mussel-inspired dopamine as a nitrogen source. Dopamine undergoes oxidative polymerization that can functionalize the surface of graphene and also introduces nitrogen atoms onto the graphene nanosheets upon pyrolysis. N-doping not only leads to improved catalytic activity, but it also provides anchoring sites for the growth of electroactive amorphous manganese oxide nanowires on the graphene nanosheets (NG/MnOx). On the basis of a Koutecky-Levich plot, it is found that the hybrid NG/MnOx catalyst exhibits excellent catalytic activity with a direct four-electron pathway in ORR. Furthermore, the hybrid electrocatalyst possesses superior stability and gives a low yield of peroxide compared to commercial Pt/C catalysts. This suggests that the unique combination of an N-doped graphene support and amorphous MnOx nanowires can synergistically improve the catalytic activity for ORR.close1

Endovascular Treatment of Symptomatic Basilar Artery Stenosis

Purpose While symptomatic basilar artery (BA) stenosis is associated with a higher risk of recurrent stroke or death, there is no consensus on the management of these patients who are refractory to antiplatelet therapy. This study retrospectively assesses the outcomes of endovascular treatment (EVT) for symptomatic BA stenosis. Materials and Methods We conducted a retrospective review of patients with symptomatic BA stenosis who underwent EVT, including angioplasty or stenting, from 2006 to 2018. A total of 15 patients, who experienced transient ischemic attacks or strokes despite dual antiplatelet therapy, were included. EVT was performed under local anesthesia after pretreatment with antiplatelet medications. Angiographic follow-up was performed at 12 and 24 months post-EVT. Clinical outcomes were evaluated using the modified Rankin Scale (mRS). Results EVT was successfully completed in all patients. Peri/post-procedural complications occurred in 33% of cases, including in-stent thrombosis, intracranial hemorrhage, and pontine infarction. At long-term follow-up (mean 98.5±80.5 months), 73.3% of patients achieved a favorable functional outcome (mRS≤2) without disability or mortality. Patients with unfavorable outcomes had previous infarcts, with 2 experiencing new pontine infarctions after stenting. Conclusion This study suggests that EVT, including angioplasty and stenting, may offer promise as a treatment option for symptomatic BA stenosis refractory to medical therapy. However, the procedure carries a notable risk of complications, especially in patients with severe stenosis and previous infarcts. Careful patient selection, based on clinical and radiological criteria, is crucial

Breast Cancer Diagnosis Using a Microfluidic Multiplexed Immunohistochemistry Platform

BACKGROUND: Biomarkers play a key role in risk assessment, assessing treatment response, and detecting recurrence and the investigation of multiple biomarkers may also prove useful in accurate prediction and prognosis of cancers. Immunohistochemistry (IHC) has been a major diagnostic tool to identify therapeutic biomarkers and to subclassify breast cancer patients. However, there is no suitable IHC platform for multiplex assay toward personalized cancer therapy. Here, we report a microfluidics-based multiplexed IHC (MMIHC) platform that significantly improves IHC performance in reduction of time and tissue consumption, quantification, consistency, sensitivity, specificity and cost-effectiveness. METHODOLOGY/PRINCIPAL FINDINGS: By creating a simple and robust interface between the device and human breast tissue samples, we not only applied conventional thin-section tissues into on-chip without any additional modification process, but also attained perfect fluid control for various solutions, without any leakage, bubble formation, or cross-contamination. Four biomarkers, estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2), progesterone receptor (PR) and Ki-67, were examined simultaneously on breast cancer cells and human breast cancer tissues. The MMIHC method improved immunoreaction, reducing time and reagent consumption. Moreover, it showed the availability of semi-quantitative analysis by comparing Western blot. Concordance study proved strong consensus between conventional whole-section analysis and MMIHC (n = 105, lowest Kendall's coefficient of concordance, 0.90). To demonstrate the suitability of MMIHC for scarce samples, it was also applied successfully to tissues from needle biopsies. CONCLUSIONS/SIGNIFICANCE: The microfluidic system, for the first time, was successfully applied to human clinical tissue samples and histopathological diagnosis was realized for breast cancers. Our results showing substantial agreement indicate that several cancer-related proteins can be simultaneously investigated on a single tumor section, giving clear advantages and technical advances over standard immunohistochemical method. This novel concept will enable histopathological diagnosis using numerous specific biomarkers at a time even for small-sized specimens, thus facilitating the individualization of cancer therapy

Ionic liquid modified graphene nanosheets anchoring manganese oxide nanoparticles as efficient electrocatalysts for Zn-air batteries

Ionic liquid (IL) modified reduced graphene oxide (rGO-IL) nanosheets anchoring manganese oxide (Mn3O4) are synthesized via a facile solution-based growth mechanism and applied to a Zn-air battery as an effective electrocatalyst for the oxygen reduction reaction (ORR). In this study, the IL moiety in these composites increases not only the conductivity of the system, but also the electrocatalytic activity compared to pristine rGO, together with the synergic effect of facilitating the ORR with the intrinsic catalytic activity of Mn3O4. Based on the Koutecky-Levich plot, we suggest that the ORR pathway of these composites is tunable with the relative amount of Mn3O4 nanoparticles supported onto the graphene sheets; for example, the ORR mechanism of the system with a lower Mn3O4 (19.2%) nanoparticle content is similar to a Pt/C electrode, i.e., a one-step, quasi-4-electron transfer, unlike that with a higher Mn3O4 (52.5%) content, which undergoes a classical two-step, 2-electron pathway. We also demonstrate the potential of these hybrid rGO-IL/Mn3O4 nanoparticles as efficient catalysts for the ORR in the Zn-air battery with a maximum peak power density of 120 mW cm(-2); a higher performance than that from commercial cathode catalysts.close584

Versatile double hydrophilic block copolymer: dual role as synthetic nanoreactor and ionic and electronic conduction layer for ruthenium oxide nanoparticle supercapacitors

The facile synthetic approach to ruthenium oxide nanoparticles using double hydrophilic block copolymers (DHBCs) and their application toward the supercapacitor are presented. Nanostructured hydrous ruthenium oxide (RuO2) nanoparticles are synthesized using a double hydrophilic block copolymer of poly(ethylene oxide)-block-poly(acrylic acid) (PEO-b-PAA) as a template, forming a micelle upon addition of the ruthenium precursor, which then transformed into RuO2 nanoparticles of controlled dimension with reducing agents. The synthesized hydrous RuO2 center dot xH(2)O nanoparticles are very stable for several months without any noticeable aggregates. Furthermore, we have demonstrated their utility in application as supercapacitors. Through annealing at 400 degrees C, we found that the crystallinity of RuO2 nanoparticles increases considerably with a simultaneous transformation of the surrounding double hydrophilic block copolymer into ionic and electronic conducting buffer layers atop RuO2 nanoparticles, which contribute to the significant enhancement of the overall specific capacitance from 106 to 962 F g(-1) at 10 mV s(-1). The RuO2 nanoparticles annealed at 400 degrees C also exhibit a superior retention of capacitance over 1000 cycles at very high charge-discharge rates at 20 A g(-1). We envision that the double hydrophilic block copolymer will provide a facile and general tool in creating functional nanostructures with controlled dimensions that are useful for various applications.close9