Exploring the surface-enhanced Raman scattering (SERS) activity of gold nanostructures embedded around nanogaps at wafer scale: Simulations and experiments

A unique way of converting free space light into a local electromagnetic field in small spaces is via metallic nanostructuring. In this work fabrication, experimental characterization and simulation of surface-enhanced Raman scattering (SERS) active specimens based on Au nanostructures are discussed. We used displacement Talbot lithography (DTL) to fabricate silicon nano-wedge substrates with Au nanostructures embedded around their apices. After the ion beam etching process, a nanogap is introduced between two Au nanostructures templated over nano-wedges, yielding specimens with SERS characteristics. The Au nanostructures and the nanogaps have symmetric and asymmetric configurations with respect to the wedges. With this nanofabrication method, various wafer-scale specimens were fabricated with highly controllable nanogaps with a size in the order of 6 nm for symmetric gaps and 8 nm for asymmetric gaps. SERS characteristics of these specimens were analyzed experimentally by calculating their analytical enhancement factor (AEF). According to finite-difference time-domain (FDTD) simulations, the Raman enhancement arises at the narrow gap due to plasmonic resonances, yielding a maximum AEF of 6.9 × 106. The results highlight the SERS activity of the nanostructures and ultimately comply with reliable substrates for practical applications

3D‐Architected Alkaline‐Earth Perovskites

3D ceramic architectures are captivating geometrical features with an immense demand in optics. In this work, an additive manufacturing (AM) approach for printing alkaline-earth perovskite 3D microarchitectures is developed. The approach enables custom-made photoresists suited for two-photon lithography, permitting the production of alkaline-earth perovskite (BaZrO 3, CaZrO 3, and SrZrO 3) 3D structures shaped in the form of octet-truss lattices, gyroids, or inspired architectures like sodalite zeolite, and C 60 buckyballs with micrometric and nanometric feature sizes. Alkaline-earth perovskite morphological, structural, and chemical characteristics are studied. The optical properties of such perovskite architectures are investigated using cathodoluminescence and wide-field photoluminescence emission to estimate the lifetime rate and defects in BaZrO 3, CaZrO 3, and SrZrO 3. From a broad perspective, this AM methodology facilitates the production of 3D-structured mixed oxides. These findings are the first steps toward dimensionally refined high-refractive-index ceramics for micro-optics and other terrains like (photo/electro)catalysis.</p

Epicardial adipose excision slows the progression of porcine coronary atherosclerosis

BACKGROUND: In humans there is a positive association between epicardial adipose tissue (EAT) volume and coronary atherosclerosis (CAD) burden. We tested the hypothesis that EAT contributes locally to CAD in a pig model. METHODS: Ossabaw miniature swine (n = 9) were fed an atherogenic diet for 6 months to produce CAD. A 15 mm length by 3–5 mm width coronary EAT (cEAT) resection was performed over the middle segment of the left anterior descending artery (LAD) 15 mm distal to the left main bifurcation. Pigs recovered for 3 months on atherogenic diet. Intravascular ultrasound (IVUS) was performed in the LAD to quantify atheroma immediately after adipectomy and was repeated after recovery before sacrifice. Coronary wall biopsies were stained immunohistochemically for atherosclerosis markers and cytokines and cEAT was assayed for atherosclerosis-related genes by RT-PCR. Total EAT volume was measured by non-contrast CT before each IVUS. RESULTS: Circumferential plaque length increased (p < 0.05) in the proximal and distal LAD segments from baseline until sacrifice whereas plaque length in the middle LAD segment underneath the adipectomy site did not increase. T-cadherin, scavenger receptor A and adiponectin were reduced in the intramural middle LAD. Relative to control pigs without CAD, 11β-hydroxysteroid dehydrogenase (11βHSD-1), CCL19, CCL21, prostaglandin D(2) synthase, gp91phox [NADPH oxidase], VEGF, VEGFGR1, and angiotensinogen mRNAs were up-regulated in cEAT. EAT volume increased over 3 months. CONCLUSION: In pigs used as their own controls, resection of cEAT decreased the progression of CAD, suggesting that cEAT may exacerbate coronary atherosclerosis

Alternative nano-lithographic tools for shell-isolated nanoparticle enhanced Raman spectroscopy substrates

Chemically synthesized metal nanoparticles (MNPs) have been widely used as surface-enhanced Raman spectroscopy (SERS) substrates for monitoring catalytic reactions. In some applications, however, the SERS MNPs, besides being plasmonically active, can also be catalytically active and result in Raman signals from undesired side products. The MNPs are typically insulated with a thin (∼3 nm), in principle pin-hole-free shell to prevent this. This approach, which is known as shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), offers many advantages, such as better thermal and chemical stability of the plasmonic nanoparticle. However, having both a high enhancement factor and ensuring that the shell is pin-hole-free is challenging because there is a trade-off between the two when considering the shell thickness. So far in the literature, shell insulation has been successfully applied only to chemically synthesized MNPs. In this work, we alternatively study different combinations of chemical synthesis (bottom-up) and lithographic (top-down) routes to obtain shell-isolated plasmonic nanostructures that offer chemical sensing capabilities. The three approaches we study in this work include (1) chemically synthesized MNPs + chemical shell, (2) lithographic substrate + chemical shell, and (3) lithographic substrate + atomic layer deposition (ALD) shell. We find that ALD allows us to fabricate controllable and reproducible pin-hole-free shells. We showcase the ability to fabricate lithographic SHINER substrates which report an enhancement factor of 7.5 × 103 ± 17% for our gold nanodot substrates coated with a 2.8 nm aluminium oxide shell. Lastly, by introducing a gold etchant solution to our fabricated SHINER substrate, we verified that the shells fabricated with ALD are truly pin-hole-free.</p

The Peru approach against the COVID-19 infodemic: Insights and strategies

The COVID-19 epidemic has spawned an "infodemic,"with excessive and unfounded information that hinders an appropriate public health response. This perspective describes a selection of COVID-19 fake news that originated in Peru and the government's response to this information. Unlike other countries, Peru was relatively successful in controlling the infodemic possibly because of the implementation of prison sentences for persons who created and shared fake news. We believe that similar actions by other countries in collaboration with social media companies may offer a solution to the infodemic problem.Revisión por pare

Ex vivo validation of magnetically actuated intravascular untethered robots in a clinical setting

Intravascular surgical instruments require precise navigation within narrow vessels, necessitating maximum flexibility, minimal diameter, and high degrees of freedom. Existing tools often lack control during insertion due to undesirable bending, limiting vessel accessibility and risking tissue damage. Next-generation instruments aim to develop hemocompatible untethered devices controlled by external magnetic forces. Achieving this goal remains complex due to testing and implementation challenges in clinical environments. Here we assess the operational effectiveness of hemocompatible untethered magnetic robots using an ex vivo porcine aorta model. The results demonstrate a linear decrease in the swimming speed of untethered magnetic robots as arterial blood flow increases, with the capability to navigate against a maximum arterial flow rate of 67 mL/min. The untethered magnetic robots effectively demonstrate locomotion in a difficult-to-access target site, navigating through the abdominal aorta and reaching the distal end of the renal artery

Longitudinal assessment of cognitive and psychosocial functioning after Hurricanes Katrina and Rita: Exploring disaster impact on middle-aged, older, and oldest-old adults

The authors examined the effects of Hurricanes Katrina and Rita on cognitive and psychosocial functioning in a lifespan sample of adults 6-14 months after the storms. Participants were recruited from the Louisiana Healthy Aging Study. Most were assessed during the immediate impact period and retested for this study. Analyses of pre- and post-disaster cognitive data confirmed that storm-related decrements in working memory for middle-aged and older adults observed in the immediate impact period had returned to pre-hurricane levels in the post-disaster recovery period. Middle-aged adults reported more storm-related stressors and greater levels of stress than the two older groups at both waves of testing. These results are consistent with a burden perspective on post-disaster psychological reactions. © 2012 Wiley Periodicals, Inc