Deformability analysis and improvement in stretchable electronics systems through finite element analysis

Stretchable electronic systems employ a combination of extremely deformable substrates with electrically conductive inks printed on their surface, on which components are connected. The absence of solid metal as conductive material greatly enhances the deformability of these systems. However, although being able to sustain high deformation, the presence of rigid components heavily affects the achievable deformation levels due to strain concentrations near the interconnection area. In order to improve stretchability under these conditions, a combination of research on materials for conductive inks and optimization of the employed layout is needed. Especially for the latter, the use of Finite Element (FE) modeling is very useful, since it allows to locate critical regions for deformation behavior and to perform design optimization and instability analyses. In this work, the authors show the application of this strategy to improve mechano-electrical performance of the system under uniaxial tension by modelling and then modifying the overall stiffness of specific sample regions. Depending on the specific need, different strategies can be adopted to intervene on stiffness changes, such as material addition to specific regions. This work shows that, in particular, a simple technique such as laser cutting can be used to tailor the local material parameters at a deeper level, thus allowing decrease in stiffness gradients and a general enhancement of electrical performances under high levels of uniaxial deformation of the sample, as also predicted in the FE analyses.acceptedVersionPeer reviewe

Regulation of DNA methylation machinery by epi-miRNAs in human cancer: emerging new targets in cancer therapy

Disruption in DNA methylation processes can lead to alteration in gene expression and function that would ultimately result in malignant transformation. In this way, studies have shown that, in cancers, methylation-associated silencing inactivates tumor suppressor genes, as effectively as mutations. DNA methylation machinery is composed of several genes, including those with DNA methyltransferases activity, proteins that bind to methylated cytosine in the promoter region, and enzymes with demethylase activity. Based on a prominent body of evidence, DNA methylation machinery could be regulated by microRNAs (miRNAs) called epi-miRNAs. Numerous studies demonstrated that dysregulation in DNA methylation regulators like upstream epi-miRNAs is indispensable for carcinogenesis; consequently, the malignant capacity of these cells could be reversed by restoring of this regulatory system in cancer. Conceivably, recognition of these epi-miRNAs in cancer cells could not only reveal novel molecular entities in carcinogenesis, but also render promising targets for cancer therapy. In this review, at first, we have an overview of the methylation alteration in cancers, and the effect of this phenomenon in miRNAs expression and after that, we conduct an in-depth discussion about the regulation of DNA methylation regulators by epi-miRNAs in cancer cells. © 2020, The Author(s), under exclusive licence to Springer Nature America, Inc

Full Control of Nanoscale Optical Transmission with a Composite Metascreen

By applying the optical nanocircuit concepts to metasurfaces, we propose an effective route to locally control light transmission over a deeply subwavelength scale. This concept realizes the optical equivalent of a transmit-array, whose use is demonstrated for light bending and focusing with unprecedented efficiency over a subwavelength distance, with crucial benefits for nano-optics applications. These findings may lead to large improvements in the manipulation of optical transmission and processing of nanoscale optical signals over conformal and Si-compatible substrates

Preparation and in vivo evaluation of nanoliposomes containing melphalan after intravitreal injection in albino rabbits

The aim of present study was to evaluate the stability and toxicity of different doses of liposomal melphalan in rabbit eyes and to investigate the pathological and electrophysiological changes after administration of different doses of free form of melphalan. Liposomes containing melphalan were prepared by solvent evaporation method and mean size of these liposomes and encapsulation efficacy of nanoliposomes were determined. In albino rabbits, intravitreal injections of 10, 20, and 40 µg doses of liposomal melphalan and Alkeran® as the commercial product was performed. The rabbits were euthanized at days 2, 7, 14, and 28, and the eyes were enucleated. Vitreous and aqueous samples and electrophysiological recordings were obtained before euthanization. Histological examination was performed after enucleation. Particle size of prepared liposomes was 143.6 ± 3.2 nm. Liposomes have protected melphalan completely from any undesirable release or hydrolysis for 48 h. In a histopathological study, signs of retinal toxicity were found in all doses in the liposomal group at least at one time point during the study. In melphalan injected eyes, histopathological toxicity was found in the 40 µg dose. Extensive variability was found in electrophysiological recordings, and significant waveform changes were found in all injected eyes at least on one occasion during the study. Intraocular administration of liposomal melphalan cannot prolong the drug clearance time of this drug in the vitreous humor. In the 40 µg injected eyes, significant retinal atrophic changes were detected in all eyes throughout the study, and electrophysiological results were consistent with histopathological findings. © 2016, The Korean Society of Pharmaceutical Sciences and Technology