Graphene-Based Interconnects for Stable Dye-Sensitized Solar Modules

We present Z-Type Dye Sensitized Solar Modules (DSSMs) with screen printed graphene-based vertical interconnects. This prevents corrosion of interconnects in contact with electrolytic species, unlike conventional Ag interconnects. By enlarging the width of single cells, or by increasing the number of cells, we get an enhancement of the aperture power conversion efficiency similar to+12% with respect to Ag-based modules, with 1000 h stability under 85 degrees C stress test. This paves the way to original design layouts with decreased dead area and increased generated power per aperture area

Graphene-Based Interfaces Do Not Alter Target Nerve Cells

Neural-interfaces rely on the ability of electrodes to transduce stimuli into electrical patterns delivered to the brain. In addition to sensitivity to the stimuli, stability in the operating conditions and efficient charge transfer to neurons, the electrodes should not alter the physiological properties of the target tissue. Graphene is emerging as a promising material for neuro-interfacing applications, given its outstanding physico-chemical properties. Here, we use graphene-based substrates (GBSs) to interface neuronal growth. We test our GBSs on brain cell cultures by measuring functional and synaptic integrity of the emerging neuronal networks. We show that GBSs are permissive interfaces, even when uncoated by cell adhesion layers, retaining unaltered neuronal signaling properties, thus being suitable for carbon-based neural prosthetic devices

Liquid-Phase Exfoliation of Graphite into Single- and Few-Layer Graphene with α-Functionalized Alkanes.

Graphene has unique physical and chemical properties, making it appealing for a number of applications in optoelectronics, sensing, photonics, composites, and smart coatings, just to cite a few. These require the development of production processes that are inexpensive and up-scalable. These criteria are met in liquid-phase exfoliation (LPE), a technique that can be enhanced when specific organic molecules are used. Here we report the exfoliation of graphite in N-methyl-2-pyrrolidinone, in the presence of heneicosane linear alkanes terminated with different head groups. These molecules act as stabilizing agents during exfoliation. The efficiency of the exfoliation in terms of the concentration of exfoliated single- and few-layer graphene flakes depends on the functional head group determining the strength of the molecular dimerization through dipole-dipole interactions. A thermodynamic analysis is carried out to interpret the impact of the termination group of the alkyl chain on the exfoliation yield. This combines molecular dynamics and molecular mechanics to rationalize the role of functionalized alkanes in the dispersion and stabilization process, which is ultimately attributed to a synergistic effect of the interactions between the molecules, graphene, and the solvent.We acknowledge funding from the European Commission through the Graphene Flagship, the FET project UPGRADE (GA-309056), the Agence Nationale de la Recherche through the LabEx project Nanostructures in Interaction with their Environment (ANR-11-LABX-0058_NIE), the International Center for Frontier Research in Chemistry (icFRC), the Belgian National Fund for Scientific Research (FNRS-FRFC), the ERC synergy grant Hetero2D, ERC PoC HiGRAPHINK, and the Engineering and Physical Sciences Research Council grants EP/K01711X/1, EP/K017144/1, and EP/L016087/1.This is the author accepted manuscript. The final version is available from the American Chemical Society via http://dx.doi.org/10.1021/acs.jpclett.6b0126

Graphene Saturable Absorbers at Terahertz Frequency from Liquid Phase Exfoliation of Graphite

© 2018 OSA. We report on the development of terahertz (THz) saturable-absorbers exploiting printable graphene inks. The achieved 80% transparency modulation at 3.5 THz makes these devices potential candidates as passive components for THz solid-state lasers.EPSR

Primary Prophylaxis for Gastrointestinal Bleeding in Children With Biliary Atresia and Portal Hypertension Candidates for Liver Transplantation: A Single-Center Experience

Background. Cirrhosis for biliary atresia (BA) is associated with risk of gastrointestinal bleeding (GB) from gastroesophageal varices due to portal hypertension. Primary prophylaxis of GB is controversial in children who are candidates for liver transplantation (LT). The aim of the study was to define the management of gastroesophageal varices and to identify the benefit of primary prophylaxis for GB in BA children waiting for LT.Methods. A retrospective single-center study including all BA children listed for LT in 2008-2016. Clinical, endoscopical, and biochemical data were analyzed.Results. Of 82 children, 50 (61%) did not receive primary prophylaxis and did not present any episode of bleeding, 16 (19.5%) underwent primary prophylaxis, and 16 (19.5%) presented spontaneous GB and received secondary prophylaxis. Children without primary prophylaxis and GB were younger than patients with primary prophylaxis and those with GB (7.7 years [range, 4.1-37.9 years] vs 11.2 years [range, 5.1-43 years]; P = .03 vs 10.7 years [range, 6.9-39.9 years], respectively; P = .004). Seventy-five percent of GB occurred in children older than 8 months. Fifteen (93.8%) children with GB presented esophageal varices (grade III = 10 [62.5%]) and 10 (62.5%) required endoscopic treatments, consisting mainly of sclerotherapy. Median time to LT was similar for children with or without bleeding (2 months [range, 0-17.7 months] vs 2.2 months [0-17.9 months], respectively; P = .89). After 45.5 months (range, 13.7-105.5 months) of follow-up, the overall patient survival was 97.6%. At the intention-to-treat analysis, the survival rate was 100% for patients without bleeding episode and 87.5% for children with GB (P = .16).Conclusions. Despite the risk of GB being not clinically predictable in children with BA waiting for LT, our experience suggests that primary prophylaxis of GB might be unnecessary in children younger than 6 months, while it should be considered in older children. Thus, the occurrence of GB does not delay the timing of transplantation

EPR dating of shells from Malhada Marsh, Rio de Janeiro, Brazil

The formation of the coastal plain of the Brazilian sea is mainly due to the fluctuation of relative sea level in the past. Armação dos Buzios or simply Buzios is a municipality in the microregion of lakes, in the state of Rio de Janeiro. In this region there is a lowland area about two meters above current sea level. This lowland areais also known as coastal plain of Una River. It is expected that during the Holocene period the sea level reached a maximum about 2.5 meters above the current level. During that time billions of mollusks lived and proliferated in the shallow waters around the coastal plain of the Una River. As they died their shells formed a layer in the soil including Malhada Marsh that belongs to the Una River plain. In this study, shells were collected from this region and dated using the techniques of Electronic Paramagnetic Resonance (EPR). Ages from 2480±130 to 4490±270 years were obtained. Radiocarbon dating were performed at the Beta Analytic Lab, USA for comparison with the EPR results. Shells ages obtained are compatible with geological data from the Holocene period relative to past sea level fluctuations

Electron Spin Resonance and Thermoluminescence dating of shells and sediments from Sambaqui (shell mound) Santa Marta II, Brazil

In Tupi, the word Sambaqui means “mound of shells”. These archaeological sites are cultural vestiges left by the prehistoric occupation of the Brazilian coast from five to six thousand years ago. Mollusks, fishes, and other marine edible foods were important for the survival of this population. The remains of foods, mainly shells, were heaped up, giving a mound of different proportions, which became part of the landscape of the Brazilian coastal plain. Due to the large number of Sambaquis in Brazil and considering that Sambaqui Santa Marta II, Laguna, SC, has not yet been dated, Electron Spin Resonance (ESR) measurements were performed in aragonite shells collected from different layers of Sambaqui Santa Marta II, starting from the base to the center of the Sambaqui. Radiocarbon analysis by Accelerator Mass Spectrometry (AMS) at Beta Analytic laboratory were also performed for comparison with ESR results. Before measurements, shells were chemically etched, after drying, were pulverized and sieved. The sediments were separated into small portions which were irradiated with gamma radiation from a 60Co source with doses from 5 up to 120 Gy. Ages around 2,000 to 4,000 years have been obtained. The results obtained are consistent with the dates of others Sambaquis of the region, possibly were built at the same time

Recent advances in the development of high-resolution 3D cadmium zinc telluride drift strip detectors

In the last two decades, great efforts have been made in the development of 3D cadmium-zinc-Telluride (CZT) detectors operating at room temperature for gamma-ray spectroscopic imaging. This work presents the spectroscopic performance of new high-resolution CZT drift strip detectors, recently developed at IMEM-CNR of Parma (Italy) in collaboration with due2lab (Italy). The detectors (19.4 mm × 19.4 mm × 6 mm) are organized into collecting anode strips (pitch of 1.6 mm) and drift strips (pitch of 0.4 mm) which are negatively biased to optimize electron charge collection. The cathode is divided into strips orthogonal to the anode strips with a pitch of 2 mm. Dedicated pulse processing analysis was performed on a wide range of collected and induced charge pulse shapes using custom 32-channel digital readout electronics. Excellent room-Temperature energy resolution (1.3% FWHM at 662 keV) was achieved using the detectors without any spectral corrections. Further improvements (0.8% FWHM at 662 keV) were also obtained through a novel correction technique based on the analysis of collected-induced charge pulses from anode and drift strips. These activities are in the framework of two Italian research projects on the development of spectroscopic gamma-ray imagers (10-1000 keV) for astrophysical and medical applications

Vertically Illuminated, Resonant Cavity Enhanced, Graphene-Silicon Schottky Photodetectors.

We report vertically illuminated, resonant cavity enhanced, graphene-Si Schottky photodetectors (PDs) operating at 1550 nm. These exploit internal photoemission at the graphene-Si interface. To obtain spectral selectivity and enhance responsivity, the PDs are integrated with an optical cavity, resulting in multiple reflections at resonance, and enhanced absorption in graphene. We get a wavelength-dependent photoresponse with external (internal) responsivity ∼20 mA/W (0.25A/W). The spectral selectivity may be further tuned by varying the cavity resonant wavelength. Our devices pave the way for developing high responsivity hybrid graphene-Si free-space illuminated PDs for optical communications, coherence optical tomography, and light-radars