Ultrasonic force microscopy: detection and imaging of ultra-thin molecular domains

The analysis of the formation of ultra-thin organic films is a very important issue. In fact, it is known that the properties of organic light emitting diodes and field effect transistors are strongly affected by the early growth stages. For instance, in the case of sexithiophene, the presence of domains made of molecules with the backbone parallel to the substrate surface has been indirectly evidenced by photoluminescence spectroscopy and confocal microscopy. On the contrary, conventional scanning force microscopy both in contact and intermittent contact modes have failed to detect such domains. In this paper, we show that Ultrasonic Force Microscopy (UFM), sensitive to nanomechanical properties, allows one to directly identify the structure of sub-monolayer thick films. Sexithiophene flat domains have been imaged for the first time with nanometer scale spatial resolution. A comparison with lateral force and intermittent contact modes has been carried out in order to explain the origins of the UFM contrast and its advantages. In particular, it indicates that UFM is highly suitable for investigations where high sensitivity to material properties, low specimen damage and high spatial resolution are required.     

Exploring creative intersections: Ernest Edmonds and his time-based generative art

This article focuses on the experience of British artist Ernest Edmonds and the influences that have informed his art practice in the past forty years. How are these influences connected? The article has an historical focus. It develops the themes within Edmonds's art and shows his connections with the ‘Systems’ artists and their forebears. In particular, the article concentrates on the encounter of Edmonds with artistic thinking about systems and process in the broad sense, as well as digital and interactive work developed from the early 1980s. As the article will demonstrate, a passion for colour, time and structure, the encounter with a number of artists inspired by Constructivism in the early 1980s, and the educational context in which Edmonds has worked from the late 1960s until the present, have offered great opportunities of interdisciplinary exchanges and ideas that had a profound impact upon the nature of his art. These influences have enabled Edmonds to explore new constructs in art through the use of technology that are a constant stimulus in his creative research, both as an artist and as an academic.     

Real-Time Global Illumination for VR Applications

Real-time global illumination in VR systems enhances scene realism by incorporating soft shadows, reflections of objects in the scene, and color bleeding. The Virtual Light Field (VLF) method enables real-time global illumination rendering in VR. The VLF has been integrated with the Extreme VR system for real-time GPU-based rendering in a Cave Automatic Virtual Environment.     

Effect of slow display on detectability when browsing large image datasets

Abstract— In this work, the effect of display temporal characteristics on detectability of signals was studied by comparing detection performance with a slow liquid‐crystal‐display (LCD) monitor and a fast, cathode‐ray‐tube (CRT) monitor when browsing multi‐slice image datasets in stack‐mode presentation. Thirteen readers evaluated 200 image sequence pairs in a two‐alternative forced choice experiment. The image sets consisted of three‐dimensional cluster lumpy backgrounds and were presented to the readers in two display devices: a three‐million‐pixel medical color LCD and a color desktop CRT. For the LCD, many inter‐gray‐level transitions are on the order of 50–60 msec, which was almost twice the frame time. The CRT had 2–5‐msec inter‐gray‐level transitions. The reader study was performed with a graphical‐user interface programmed using direct calls to OpenGL libraries to precisely control the browsing speed. The results were analyzed in terms of the difference in reader performance for each reader and each display, between a browsing speed of 20 and 50 frames per sec (fps). Average reader performance difference between 20 and 50 fps was measured to be 0.049 and 0.156 for the CRT and LCD monitors, respectively. The corresponding drop in reader performance associated with slow display was 0.11.     

Stabilizability of switched linear systems does not imply the existence of convex Lyapunov functions

Counterexamples are given which show that a linear switched system (with controlled switching) that can be stabilized by means of a suitable switching law does not necessarily admit a convex Lyapunov function. Both continuous- and discrete-time cases are considered. This fact contributes in focusing the difficulties encountered so far in the theory of stabilization of switched system. In particular the result is in contrast with the case of uncontrolled switching in which it is known that if a system is stable under arbitrary switching then admits a polyhedral norm as a Lyapunov function.     

A model of checkpoint behavior for applications that have I/O

Due to the increase and complexity of computer systems, reducing the overhead of fault tolerance techniques has become important in recent years. One technique in fault tolerance is checkpointing, which saves a snapshot with the information that has been computed up to a specific moment, suspending the execution of the application, consuming I/O resources and network bandwidth. Characterizing the files that are generated when performing the checkpoint of a parallel application is useful to determine the resources consumed and their impact on the I/O system. It is also important to characterize the application that performs checkpoints, and one of these characteristics is whether the application does I/O. In this paper, we present a model of checkpoint behavior for parallel applications that performs I/O; this depends on the application and on other factors such as the number of processes, the mapping of processes and the type of I/O used. These characteristics will also influence scalability, the resources consumed and their impact on the IO system. Our model describes the behavior of the checkpoint size based on the characteristics of the system and the type (or model) of I/O used, such as the number I/O aggregator processes, the buffering size utilized by the two-phase I/O optimization technique and components of collective file I/O operations. The BT benchmark and FLASH I/O are analyzed under different configurations of aggregator processes and buffer size to explain our approach. The model can be useful when selecting what type of checkpoint configuration is more appropriate according to the applications’ characteristics and resources available. Thus, the user will be able to know how much storage space the checkpoint consumes and how much the application consumes, in order to establish policies that help improve the distribution of resources.

     

Ethyl oleate ozonide as an epoxidation tool of C60 and C70 fullerenes

When dissolved in ethyl oleate secondary ozonide, both C₆₀ and C₇₀ fullerenes undergo a series of epoxidation reactions. The pseudofirst-order kinetic rate constants of this process were determined spectrophotometrically at various temperatures and the activation energy for C₆₀ epoxidation through ethyl oleate ozonide was found at 25.9 kcal/mol. Furthermore, C₆₀ was found more reactive than C₇₀ with the ozonide. The kinetics rate constants of C₆₀ epoxidation with ethyl oleate ozonide were compared with the C₆₀ photo-oxidation and auto-oxidation determined in pure ethyl oleate. The epoxidation of fullerenes starts from the homolysis of the peroxide group of the 1,2,4-trioxolane ring of ethyl oleate secondary ozonide. Thus, it is suggested that fullerenes have a potential as decomposition agents of secondary ozonides in some technological applications.     

How can Cleaner Production practices contribute to meet ISO 14001 requirements? Critical analysis from a survey with industrial companies

The companies’ needs to adopt changes in their way of production to maximize the environmental performance required by their stakeholders, and at the same time, to maximize their economic and market performance, have made them seek for environmental strategies and certifications. In this sense, the Cleaner Production and the Environmental Management System based on ISO 14001 have been, respectively, presented, since the main objective of this research is to identify and analyze Cleaner Production contributions to comply with ISO 14001 requirements. For such, a survey research has been carried out in Brazilian industrial companies certified by ISO 14001. We have identified the main performance factors by leading practices and variables of Cleaner Production that contribute to the compliance with the standard requirements by companies. Thus, it has been noted that Cleaner Production is an important strategy for the preparation of companies for certification as well as for improving their environmental performance.     

Sorafenib delivery nanoplatform based on superparamagnetic iron oxide nanoparticles magnetically targets hepatocellular carcinoma

Currently,sorafenib is the only systemic therapy capable of increasing overall survival of hepatocellular carcinoma patients.Unfortunately,its side effects,particularly its overall toxicity,limit the therapeutic response that can be achieved.Superparamagnetic iron oxide nanoparticles (SPIONs) are very attractive for drug delivery because they can be targeted to specific sites in the body through application of a magnetic field,thus improving intratumoral accumulation and reducing adverse effects.Here,nanoformulations based on polyethylene glycol modified phospholipid micelles,loaded with both SPIONs and sorafenib,were successfully prepared and thoroughly investigated by complementary techniques.This nanovector system provided effective drug delivery,had an average hydrodynamic diameter of about 125 nm,had good stability in aqueous medium,and allowed controlled drug loading.Magnetic analysis allowed accurate determination of the amount of SPIONs embedded in each micelle.An in vitro system was designed to test whether the SPION micelles can be efficiently held using a magnetic field under typical flow conditions found in the human liver.Human hepatocellular carcinoma (HepG2) cells were selected as an in vitro system to evaluate tumor cell targeting efficacy of the superparamagnetic micelles loaded with sorafenib.These experiments demonstrated that this delivery platform is able to enhance sorafenib's antitumor effectiveness by magnetic targeting.The magnetic nanovectors described here represent promising candidates for targeting specific hepatic tumor sites,where selective release of sorafenib can improve its efficacy and safety profile.     

Protein kinase C-dependent in vivo phosphorylation of prourokinase leads to the formation of a receptor competitive antagonist

We recently reported that in vivo phosphorylation of urokinase-type plasminogen activator on Ser138/303 prevents its catalytic-independent ability to promote myelomonocytic cell adherence and motility. We now show that Ca2+ activated, phospholipid-dependent protein kinase C from rat brain phosphorylates in vitro a peptide corresponding to prourokinase residues 133-143 (DGKKPSSPPEE) and the full-length molecule on Ser138/139. The in vivo involvement of the protein kinase C isoenzyme family is supported by the finding that inhibition of kinase C activity prevents prourokinase phosphorylation on Ser138/303 in A431 human carcinoma cells. Conversely, a short treatment of A431 cells with phorbol myristate acetate increases the extent of phosphorylated prourokinase and, concomitantly, affects its function; under these conditions, the capability of prourokinase to up-regulate U937 monocyte-like cell adherence is severely impaired, although receptor binding is unaltered. By the aid of a "phosphorylation-like" variant (Ser138 to Glu) we show that modification of Ser138 is sufficient to confer to prourokinase the antagonistic properties observed following in vivo stimulation of protein kinase C activity. These observations provide the first evidence that protein kinase C directs the formation of a receptor competitive antagonist by regulating the in vivo phosphorylation state of prourokinase.