Zinc porphyrin-driven assembly of gold nanofingers

Nanofingers of gold covered by porphyrins are prepared by a combination of atomic manipulation and surface self-organization. A submonolayer of zinc(II) 5,10,15,20-tetrakis(4-tert-butylphenyl)-porphyrin (ZnTBPP) axially ligated to a self-assembled monolayer of 4-aminothiophenol (4-ATP) on Au(111) is prepared and studied using a combination of ultrahigh vacuum techniques. Under the electric field produced by the STM tip, the relatively weakly bound Au surface atoms along the discommensuration lines become mobile due to the strong bond to 4-ATP, while the tendency of the porphyrins towards self-assembly result in a collective motion of gold clusters. The clusters diffuse onto the surface following well-defined pathways along the [112] direction and then reach the step edges where they assembled, thus forming nanofingers. First-principles density functional theory calculations demonstrate the reduction of the binding energies between the surface gold clusters and the substrate induced by adsorption of thiols. Scanning tunneling microscopy images show assemblies across three adjacent discommensuration lines of the Au(111)-(22 x square root 3) reconstruction, which collectively diffuse along these lines to form islands nucleated at step edges.     

Perceptual limits for a robotic rehabilitation environment using visual feedback distortion.

Imperceptible visual distortion, in the form of a disguised progression of performance goals, may be a helpful addition to rehabilitation after stroke and other brain injuries. This paper describes work that has been done to lay the groundwork for testing this hypothesis. We have constructed and validated an experimental environment that provides controllable visual distortion and allows precise force and position measurements. To estimate the amount of visual distortion that should be imperceptible, we measured the limits for force and distance/position perception in our rehabilitation environment for young and elderly unimpaired subjects and for a single traumatic brain injury (TBI) patient. We found the Just Noticeable Difference (JND) for produced force to be 19.7% (0.296 N) and the JND for movement distance/finger position to be 13.0% (3.99 mm) for young subjects (ages 18-35). For elderly subjects (ages 61-80), the JND for force was measured to be 31.0% (0.619 N) and the JND for distance/po'sition was 16.1% (5.01 mm). JNDs of 46.0% (0.920 N) and 45.0% (14.8 mm) were found for the motor-impaired individual. In addition, a subject's rating of effort was found to be profoundly influenced by visual feedback concerning the force magnitude. Even when this feedback was distorted, it accounted for 99% of the variance of the effort rating. These results indicate that substantial visual distortions should be imperceptible to the subject, and that visual feedback can be used to influence the subject's perceived experience in our robotic environment. This means that we should be able to use imperceptible visual distortion to alter a patient's perception of therapeutic exercise in a robotic environment.     

Visualizing 3D objects from 2D cross sectional images displayed in-situ versus ex-situ.

The present research investigates how mental visualization of a 3D object from 2D cross sectional images is influenced by displacing the images from the source object, as is customary in medical imaging. Three experiments were conducted to assess people’s ability to integrate spatial information over a series of cross sectional images in order to visualize an object posed in 3D space. Participants used a hand-held tool to reveal a virtual rod as a sequence of cross-sectional images, which were displayed either directly in the space of exploration (in-situ) or displaced to a remote screen (ex-situ). They manipulated a response stylus to match the virtual rod’s pitch (vertical slant), yaw (horizontal slant), or both. Consistent with the hypothesis that spatial colocation of image and source object facilitates mental visualization, we found that although single dimensions of slant were judged accurately with both displays, judging pitch and yaw simultaneously produced differences in systematic error between in-situ and ex-situ displays. Ex-situ imaging also exhibited errors such that the magnitude of the response was approximately correct but the direction was reversed. Regression analysis indicated that the in-situ judgments were primarily based on spatiotemporal visualization, while the ex-situ judgments relied on an ad hoc, screen-based heuristic. These findings suggest that in-situ displays may be useful in clinical practice by reducing error and facilitating the ability of radiologists to visualize 3D anatomy from cross sectional images. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abstract interpretation based verification of temporal properties for BioAmbients

This paper concerns the application of formal methods to biological systems, modeled specifically in BioAmbients, a variant of the Mobile Ambients calculus. Following the semantic-based approach of abstract interpretation, we define a new static analysis that computes an abstract transition system. Our analysis has two main advantages with respect to the analyses appearing in the literature: (i) it is able to address temporal properties which are more general than invariant properties; (ii) it supports, by means of a particular labeling discipline, the validation of systems where several copies of an ambient may appear.We also design new weaker and more efficient analyses by means of simple widening operators.     

Hepatocellular Carcinoma in Patients with a Sustained Response to Anti-Hepatitis C Therapy

Hepatocellular carcinoma (HCC) is a common, life-threatening complication of longstanding infection with the hepatitis C virus (HCV), likely a consequence of the direct oncogenic activity of the virus cooperating with liver cell inflammation in transforming the liver into a mitogenic and mutagenic environment. The achievement of a sustained virological response (SVR) to interferon-based therapies has been shown to benefit the course of hepatitis C in terms of reduced rates of liver-related complications and mortality from all causes. Interestingly, while achievement of an SVR is associated with a negligible risk of developing clinical decompensation over the years, the risk of HCC is not fully abrogated following HCV clearance, but it remains the dominant complication in all SVR populations. The factors accounting for such a residual risk of HCC in SVR patients are not fully understood, yet the persistence of the subverted architecture of the liver, diabetes and alcohol abuse are likely culprits. In the end, the risk of developing an HCC in SVR patients is attenuated by 75% compared to non-responders or untreated patients, whereas responders who develop an HCC may be stratified in different categories of HCC risk by a score based on the same demographic and liver disease-based variables, such as those that predict liver cancer in viremic patients. All in all, this prevents full understanding of those factors that drive HCC risk once HCV has been eradicated. Here, we critically review current understanding of HCC in SVR patients focusing on factors that predict residual risk of HCC among these patients and providing a glimpse of the expected benefits of new anti-HCV regimens based on direct antiviral agents.     

Electrospun nanofibrous membranes for solid-phase extraction of estriol from aqueous solution

Nowadays, efficient, economical, and environmentally friendly materials for the removal of emerging contaminants from the aquatic environment have been sought. Electrospun nanofibrous membranes contain fibers with diameters of submicron or nanometer scale, making them very promising adsorbent materials for use in several areas. In this context, the present study aims to synthesize and apply polymeric nanofiber membranes for solid-phase extraction of estriol from aqueous solution. Nanofiber membranes of poly(ε-caprolactone) (PCL) and polyamide-6 (PA-6) were tested as adsorbent materials and characterized by different techniques. The electrospinning time was evaluated, and the highest removal obtained for the PA-6 nanofiber was 76.5%, spun for 100 min, whereas for the PCL nanofiber, 80% time-independent removal was obtained. The thinner nanofibers had a larger contact area, therefore higher removals, except for the PCL nanofiber, which presented exposed beads on smaller thicknesses that impaired their efficiency. Furthermore, the nanofiber membranes have been applied for the determination of 1.0 mg L⁻¹ of E3 in superficial water sample with satisfactory results. These aspects demonstrate that the synthesized nanofibers present an efficient material for the extraction of estriol: of high simplicity, low cost, and using green chemistry. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47189.     

Development of Novel Amides as Noncovalent Inhibitors of Immunoproteasomes

The development of immunoproteasome-selective inhibitors is a promising strategy for treating hematologic malignancies, autoimmune and inflammatory diseases. In this context, we report the design, synthesis, and biological evaluation of a new series of amide derivatives as immunoproteasome inhibitors. Notably, the designed compounds act as noncovalent inhibitors, which might be a promising therapeutic option because of the lack of drawbacks and side effects associated with irreversible inhibition. Among the synthesized compounds, we identified a panel of active inhibitors with K_i values in the low micromolar or sub-micromolar ranges toward the β5i and/or β1i subunits of immunoproteasomes. One of the active compounds was shown to be the most potent and selective inhibitor with a K_i value of 21 nm against the single β1i subunit. Docking studies allowed us to determine the mode of binding of the molecules in the catalytic site of immunoproteasome subunits.     

The Effect of CH<Subscript>4</Subscript> on NH<Subscript>3</Subscript>-SCR Over Metal-Promoted Zeolite Catalysts for Lean-Burn Natural Gas Vehicles

We present a systematic investigation of the deNO_x activity of two commercial metal exchanged zeolite NH₃-SCR catalysts, a Cu-SAPO and a Fe-BEA, in view of their application to the exhaust after-treatment systems of lean-burn natural gas vehicles. The catalytic activity data collected under realistic operating conditions, representative of the after-treatment system of lean-burn vehicles, were compared to those obtained adding methane to the gas feed stream in order to assess the impact of this hydrocarbon, which is usually emitted from natural gas engines, on the NH₃-SCR catalytic chemistry. Our results indicate a negligible impact of methane on the SCR activity at all conditions, but in the presence of a large excess of NO₂ at T?>?400 °C due to methane oxidation by NO₂. The data collected over the two individual metal-promoted zeolites were also compared with those obtained combining both catalysts in sequential arrangements, in order to take advantage of their complementary high activities in different temperature ranges. The Fe-zeolite?+?Cu-zeolite sequence outperformed the two individual components in terms of both overall deNOx efficiency and N₂O selectivity, and was equally insensitive to methane.