An electrochemical exfoliation method for the production of graphene oxide and its characterization by electrochemical techniques are presented here. Graphite rods are used as working electrode in a ...three‐electrode electrochemical cell, and electro‐exfoliation is achieved by applying anodic polarization in a sulfuric acid solution. The electrochemical process involved two steps characterized by an intercalation at lower potential and an exfoliation at higher potential. The electrochemical behavior of the produced GO is studied through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). X ray Photoelectronic Spectroscopy (XPS), Raman spectroscopy, Transmission Electron Microscopy (TEM), and Atomic Force Microscopy (AFM) are employed to characterize the structural and chemical properties of the exfoliated GO. The results demonstrate that the electrochemical exfoliation method yields GO materials with varying degrees of oxidation, defect density, and crystallite size, depending on the applied potential and acid concentration. The graphene oxide samples exhibited distinct electrochemical properties, including charge transfer resistance, interfacial capacitance, and relaxation times for the charge transfer, as revealed by CV and EIS measurements with a specifically selected redox probe. The comprehensive characterization performed provides valuable insights into the structure‐property relationships of the GO materials synthesized through electrochemical exfoliation of graphite.
Between the sheets: The Intercalation‐Exfoliation (I‐E) method was successfully applied to produce graphene oxide (GO) materials with adjustable oxidation levels, defect density, and crystallite size by tuning applied potential and electrolyte concentration. Investigating the electrochemical properties of these GO samples via CV and EIS measurements with a selected redox probe establishes meaningful correlations between their structural features and performance.
Metastatic hepatocellular carcinoma (HCC) to the right atrium without invasion of the inferior vena cava is a very rare and difficult diagnosis, especially when the primary tumour is yet to be known. ...A 68-year-old man with symptoms of heart failure was admitted to the emergency department; his transthoracic echocardiogram showed a mass comprehending almost the totality of the right atrium, obliterating its entrance nearly completely and impeding the normal auricular–ventricular flux, described as a possible auricular myxoma. The patient was promptly transferred to cardiothoracic surgery and submitted to an urgent surgery to completely remove the mass, which was macroscopically described as suspected of malignancy. Further investigation demonstrated a single nodule in the liver with malignant imaging characteristics, and the histology confirmed the diagnosis of metastatic HCC of the right atrium, without metastatic disease elsewhere. He was then submitted to radiofrequency ablation and medicated with sorafenib. The disease progressed slowly but subsequently involved the inferior vena cava and portal vein, culminating in his death 4 years and 3 months after the diagnosis. Although the prognosis for metastatic HCC may be poor, especially with intracavitary heart metastasis, this case shows that an aggressive initial approach with surgical metastasectomy may prolong the median survival of the patients.
Supported membranes on top of polymer cushions are interesting models of biomembranes as cell membranes are supported on a polymer network of proteins and sugars. In this work lipid vesicles formed ...by a mixture of 30% 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 70% 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) are assembled on top of a polyelectrolyte multilayer (PEM) cushion of poly(allylamine hydrochloride) (PAH) and poly(styrene sodium sulfonate) (PSS). The assembly results in the formation of a bilayer on top of the PEM as proven by means of the quartz crystal microbalance with dissipation technique (QCM-D) and by cryo-transmission electron microscopy (cryo-TEM). The electrical properties of the bilayer are studied by electrochemical impedance spectroscopy (EIS). The bilayer supported on the PEMs shows a high resistance, on the order of 107 Ω cm2, which is indicative of a continuous, dense bilayer. Such resistance is comparable with the resistance of black lipid membranes. This is the first time that such values are obtained for lipid bilayers supported on PEMs. The assembly of polyelectrolytes on top of a lipid bilayer decreases the resistance of the bilayer up to 2 orders of magnitude. The assembly of the polyelectrolytes on the lipids induces defects or pores in the bilayer which in turn prompts a decrease in the measured resistance.
Common features of many Internet of Things (IoT) networks are that devices: 1) work in an asynchronous manner, 2) are prone to fail, and 3) have reduced memory and need to operate in remote or ...inaccessible regions, where battery replacement or recharging is difficult. Traditional communication protocols are not designed to work under these conditions. In this paper, we present two novel gossip-based protocols designed to operate in asynchronous IoT networks, where any number of devices are allowed to fail (as long as the network remains minimally connected), and that require, in order to not compromise the efficiency and longevity of the devices, a low number of messages to be sent even when the devices have a reduced memory. The main difference between both protocols is related to their management of memory and number of messages sent (consumed energy). The first protocol (battery-efficient protocol) allows to reduce battery consumption while still having a good time performance, but needs quadratic memory, like traditional versions. The second protocol (memory-optimal protocol) only needs linear memory to store and manage the rumors, and is capable of significantly reducing the number of messages sent, while obtaining similar (or, in many cases, better) performance than the first protocol. Both protocols are formally proved to be correct, and upper and lower limits of their number of messages sent are determined. These theoretical limits, however, differ so much among them that they do not permit to guess the number of messages that a real case may require. Hence, the practical performance of both protocols is assessed with experiments.
Supported membranes on polymer cushions are of fundamental interest as models for cell membranes. The use of polyelectrolyte multilayers (PEMs) assembled by the layer by layer (LbL) technique as ...supports for a bilayer allows for easy integration of the lipid bilayer on surfaces and devices and for nanoscale tunable spacing of the lipid bilayer. Controlling ionic permeability in lipid bilayers supported on PEMs triggers potential applications in sensing and as models for transport phenomena in cell membranes. Lipid bilayers displaying gramicidin channels are fabricated on top of polyallylamine hydrochloride (PAH) and polystyrene sulfonate (PSS) multilayer films, by the assembly of vesicles of phosphatidylcholine and phosphatidylserine, 50 : 50 M/M, carrying gramicidin (GA). Quartz crystal microbalance with dissipation shows that the vesicles with GA fuse into a bilayer. Atomic force microscopy reveals that the presence of GA alters the bilayer topography resulting in depressions in the bilayer of around 70 nm in diameter. Electrochemical impedance spectroscopy (EIS) studies show that supported bilayers carrying GA have smaller resistances than the bilayers without GA. Lipid layers carrying GA display a higher conductance for K
than for Na
and are blocked in the presence of Ca
.
Extrahepatic metastasis of hepatocellular carcinoma is usually associated with extensive intrahepatic lesions. Hepatoid adenocarcinoma is a rare variant of extrahepatic malignant adenocarcinoma that ...exhibits remarkable histological and immunohistochemical similarity to hepatocellular carcinoma, which can result in an underestimated diagnosis.This case report describes a patient with a newly found gallbladder polyp. Following cholecystectomy, the initial histological and immunohistochemical evaluation suggested a metastasis of hepatocellular carcinoma. However, after multiple scans, no primary intrahepatic lesion was found. A subsequent review of the gallbladder specimens showed negative staining for CK7 and CK19, leading to a diagnosis of hepatoid carcinoma of the gallbladder.
Introduction
Wilson’s disease (WD) is associated with a variety of movement disorders and progressive neurological dysfunction. The aim of this study was to correlate baseline brain magnetic ...resonance imaging (MRI) features with clinical phenotype and long-term outcomes in chronically treated WD patients.
Methods
Patients were retrospectively selected from an institutional database. Two experienced neuroradiologists reviewed baseline brain MRI. Functional assessment was performed using the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) scale, and disease severity was classified using the Global Assessment Scale for Wilson's Disease (GASWD).
Results
Of 27 patients selected, 14 were female (51.9%), with a mean (standard deviation SD) age at onset of 19.5 (7.1) years. Neurological symptoms developed in 22 patients (81.5%), with hyperkinetic symptoms being the most common (70.4%). Baseline brain MRI showed abnormal findings in 18 cases (66.7%), including T2 hyperintensities in 59.3% and atrophy in 29.6%. After a mean (SD) follow-up of 20.9 (11.0) years, WD patients had a mean score of 19.2 (10.2) on WHODAS 2.0 and 6.4 (5.7) on GASWD. The presence of hyperkinetic symptoms correlated with putaminal T2 hyperintensities (
p
= 0.003), putaminal T2 hypointensities (
p
= 0.009), and mesencephalic T2 hyperintensities (
p
= 0.009). Increased functional disability was associated with brain atrophy (
p
= 0.007), diffusion abnormalities (
p
= 0.013), and burden of T2 hyperintensities (
p
= 0.002). A stepwise regression model identified atrophy as a predictor of increased WHODAS 2.0 (
p
= 0.023) and GASWD (
p
= 0.007) scores.
Conclusions
Atrophy and, to a lesser extent, deep T2 hyperintensity are associated with functional disability and disease severity in long-term follow-up of WD patients.
The purpose of this study was to ascertain a novel prognostic index via recursive partitioning analysis (RPA) in hepatocellular carcinoma (HCC) patients being treated with the combination of ...atezolizumab plus bevacizumab (ABE) in first-line setting.
A total of 784 patients with HCC were included in the analysis.
RPA identified three groups of patients: high-risk Child-Pugh B (CP-B) patients; CP-A and Albumin-Bilirubin (ALBI)-2 patients; CP-A and ALBI-1 patients with macrovascular invasion (MVI), and alpha-fetoprotein (α-FP) ≥400 ng/ml; intermediate-risk CP-A and ALBI-1 patients with aspartate aminotransferase (AST) normal value (NV), and αFP ≥400 ng/ml, but without MVI; CP-A and ALBI-1 patients with AST increased value (IV), and neutrophil-lymphocyte ratio (NLR) ≥3, but without MVI; low-risk (CP-A and ALBI-1 patients with AST NV, and αFP <400 ng/ml, but without MVI; CP-A and ALBI-1 patients with AST IV, and NLR <3, but without MVI; CP-A and ALBI-1 patients with MVI, and αFP <400 ng/ml). Overall survival was 7.0 months in high-risk patients (20.8%), 14.2 months in intermediate-risk patients (19.1%), and 22.5 months in low-risk patients (60.1%).
The ABE index allows for easy stratification of HCC patients treated with the combination of ABE in first-line setting.
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•High resistivity lipid bilayer supported on PEMs for sensors or selective transport.•Carriers integration in lipid bilayers for controlling ionic permeability.•Supported lipid ...membranes as a model system for developing a sensing interface.
Supported Lipid Bilayers (SLBs) on Polyelectrolyte Multilayers (PEMs) have large potential as models for developing sensor devices. SLBs can be designed with receptors and channels, which benefit from the biological environment of the lipid layers, to create a sensing interface for ions and biomarkers. PEMs assembled by the Layer-by-Layer (LBL) technique and used as supports for a lipid bilayer enable an easy integration of the bilayer on almost any surface and device. For electrochemical sensors, LBL assembly enables nanoscale tunable separation of the lipid bilayer from the electrode surface, avoiding undesired effects of the electrode surface on the lipid bilayers. We study the fabrication of valinomycin-doped SLBs on PEMs as a model system for biophysical studies and for selective ion sensing. SLBs are fabricated from dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylserine (DOPS) 50:50 vesicles doped with valinomycin, as a K+-selective carrier. SLBs were deposited on electrodes coated with poly(allyl amine hydrochloride) (PAH) and poly(styrene sodium sulfonate) (PSS) multilayers. Lipid bilayer formation was monitored by using Quartz Crystal Microbalance with Dissipation (QCMD) technique and Atomic Force Microscopy (AFM). Electrochemical impedance spectroscopy (EIS) and potentiometric measurements were performed to assess K+ selectivity over other ions and the potential of valinomycin-doped SLBs for K+-sensing.
The effect of the grafting density on the molecular transport through thermoresponsive brushes of poly(N-isopropylacrylamide) (PNIPAM) grafted onto flat gold substrates was investigated using ...voltammetry and impedance spectroscopy. PNIPAM brush layers were synthesized at four different grafting densities using surface-initiated atom transfer radical polymerization (SI-ATRP) from mixed self-assembled monolayers of ω-mercaptoundecyl bromoisobutyrate and undecanethiol chemisorbed on gold surfaces. Tethered PNIPAM layers with grafting densities resulting from initiator concentrations lower than 25% in the thiol monolayer show the same transport properties as the initial self-assembled monolayer before brush synthesis. For higher grafting densities, the diffusion coefficients, D, of the K3Fe(CN)6/K4Fe(CN)6 redox probe is 7 orders of magnitude smaller than those typically measured in aqueous solutions and independent of whether the brush is collapsed or swollen. The collapse of the PNIPAM brush drives a hydrophilic/hydrophobic transition in addition to structural/conformational transformations of the grafted layers, resulting in still smaller values of D. However, these changes do not lead to a blocking effect on the active area of the gold surface, which is only determined by pinholes or discontinuities in the thiol initiator monolayer. These results are only observed for thin PNIPAM brush layers.
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