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Despite broad interest in aluminum gallium nitride (AlGaN) optoelectronic devices for deep ultraviolet (DUV) applications, the performance of conventional Al(Ga)N planar devices drastically decays when approaching the AlN end, including low internal quantum efficiencies (IQEs) and high device operation voltages. Here we show that these challenges can be addressed by utilizing nitrogen (N) polar Al(Ga)N nanowires grown directly on Si substrate. By carefully tuning the synthesis conditions, a record IQE of 80% can be realized with N-polar AlN nanowires, which is nearly ten times higher compared to high quality planar AlN. The first 210 nm emitting AlN nanowire light emitting diodes (LEDs) were achieved, with a turn on voltage of about 6 V, which is significantly lower than the commonly observed 20 – 40 V. This can be ascribed to both efficient Mg doping by controlling the nanowire growth rate and N-polarity induced internal electrical field that favors hole injection. In the end, high performance N-polar AlGaN nanowire LEDs with emission wavelengths covering the UV-B/C bands were also demonstrated.

We report on the design and fabrication of high performance AlxGa1−xN nanowire ultraviolet (UV) light-emitting diodes (LEDs) on silicon substrate by molecular beam epitaxy. The emission wavelength and surface morphology of nanowires can be controlled by varying the growth parameters that include substrate temperatures and/or Aluminum/Gallium flux ratios. The devices exhibit excellent current-voltage characteristics with relatively low resistance. Such nanowire LEDs generate strong emission in the UV-B band tuning from 290 nm to 330 nm. The electroluminescence spectra show virtually invariant blue-shift under injection current from 50 mA to 400 mA, suggesting the presence of a negligible quantum-confined Stark effect. Moreover, we have shown that, the AlGaN nanowire LEDs using periodic structures, can achieve high light extraction efficiency of ~ 89% and 92% for emissions at 290nm and 320nm, respectively. The randomly arranged nanowire 290 nm UV LEDs exhibit light extraction efficiency of ~ 56% which is higher compared to current AlGaN based thin-film UV LEDs.

An imbalance in the reactive oxygen species (ROS) homeostasis is involved in the pathogenesis of oxidative stress-related diseases. Astaxanthin, a xanthophyll carotenoid with high antioxidant capacities, has been shown to prevent the first stages of oxidative stress. Here, we evaluate the antioxidant capacities of astaxanthin included within hydroxypropyl-beta-cyclodextrin (CD-A) to directly and indirectly reduce the induced ROS production. First, chemical methods were used to corroborate the preservation of astaxanthin antioxidant abilities after inclusion. Next, antioxidant scavenging properties of CD-A to inhibit the cellular and mitochondrial ROS by reducing the disturbance in the redox state of the cell and the infiltration of lipid peroxidation radicals were evaluated. Finally, the activation of endogenous antioxidant PTEN/AKT, Nrf2/HO-1, and NQOI gene and protein expression supported the protective effect of CD-A complex on human endothelial cells under stress conditions. Moreover, a nontoxic effect on HUVEC was registered after CD-A complex supplementation. The results reported here illustrate the need to continue exploring the interesting properties of this hydrophilic antioxidant complex to assist endogenous systems to counteract the ROS impact on the induction of cellular oxidative stress state.

(1) Melanoma is the most aggressive dermatologic malignancy, with an estimated 106,110 new cases to be diagnosed in 2021. The annual incidence rates continue to climb, which underscores the critical importance of improving the methods to prevent this disease. The interventions to assist with melanoma prevention vary and typically include measures such as UV avoidance and the use of protective clothing, sunscreen, and other chemopreventive agents. However, the evidence is mixed surrounding the use of these and other interventions. This review discusses the heritable etiologies underlying melanoma development before delving into the data surrounding the preventive methods highlighted above. (2) A comprehensive literature review was performed to identify the clinical trials, observational studies, and meta-analyses pertinent to melanoma prevention and incidence. Online resources were queried to identify epidemiologic and clinical trial information. (3) Evidence exists to support population-wide screening programs, the proper use of sunscreen, and community-targeted measures in the prevention of melanoma. Clinical evidence for the majority of the proposed preventive chemotherapeutics is presently minimal but continues to evolve. (4) Further study of these chemotherapeutics, as well as improvement of techniques in artificial intelligence and imaging techniques for melanoma screening, is warranted for continued improvement of melanoma prevention.

Biomaterial surface properties, via alterations in the adsorbed protein layer, and the presence of specific functional groups can influence integrin binding specificity, thereby modulating cell adhesion and differentiation processes. The adsorption of fibronectin, a protein directly involved in osteoblast adhesion to the extracellular matrix, has been related to different physical and chemical properties of biomaterial surfaces. This study used blasting particles of different sizes and chemical compositions to evaluate the response of MG63 osteoblast-like cells on smooth and blasted titanium surfaces, with and without fibronectin coatings, by means of real-time reverse transcription-polymerase chain reaction (qRT-PCR) assays. This response included (a) expression of the α 5 , α v and α 3 integrin subunits, which can bind to fibronectin through the RGD binding site, and (b) expression of alkaline phosphatase (ALP) and osteocalcin (OC) as cell-differentiation markers. ALP activity and synthesis of OC were also tested. Cells on SiC-blasted Ti surfaces expressed higher amounts of the α 5 mRNA gene than cells on Al 2 O 3 -blasted Ti surfaces. This may be related to the fact that SiC-blasted surfaces adsorbed higher amounts of fibronectin due to their higher surface free energy and therefore provided a higher number of specific cell-binding sites. Fn-coated Ti surfaces decreased α 5 mRNA gene expression, by favoring the formation of other integrins involved in adhesion over α 5 β 1 . The changes in α 5 mRNA expression induced by the presence of fibronectin coatings may moreover influence the osteoblast differentiation pathway, as fibronectin coatings on Ti surfaces also decreased both ALP mRNA expression and ALP activity after 14 and 21 days of cell culture.

Migration and proliferation of lens epithelial cells (LECs) are based on interactions between cellular integrins and extracellular matrix proteins (ECMs). We were able to design polymers substituted with COO- and SO3- groups that counteract LEC proliferation through modification of the integrin/ECM interaction. The objective of this study was to compare the cell proliferation-inhibiting properties of differently substituted copolymers with those of a homopolymer. Polymers were synthesized by radical polymerization and characterized by nuclear resonance spectroscopy. Second-passage rabbit LECs were cultured either on PMMA homopolymers (control) or on substituted PMMA copolymers. Cells were counted on days 2, 7, and 17. Cell vitality was evaluated by trypan blue staining. Experiments were run in quadruplicate. Statistical analysis was performed using the Wilcoxon test and the Mann-Whitney U-test. Compared with control, cells cultured on copolymers grew to significantly lower cell numbers. The inhibitory effect became evident at day 2 after seeding and persisted throughout the experiment. Different ratios of COO-/SO3- substitutions yielded different grades of inhibition. No toxic effect was seen on rabbit LECs. The tested copolymers inhibit cell proliferation and are nontoxic. Further evaluation could lead to the development of new intraocular lens materials that prevent secondary cataract.

No-reflow is an unpredictable complication following percutaneous coronary intervention. No- reflow is associated with myocardial ischemia and infarction and increased mortality. A case of refractory no-reflow is described that was rapidly and successfully treated with multiple infusions of high doses of verapamil and adenosine applied directly at the site of no-reflow through a perfusion catheter.