TG/FTIR/MS study on the influence of nanoparticles content upon the thermal decomposition of starch/poly(vinyl alcohol) montmorillonite nanocomposites

The effect of the nanoclay content on the thermal decomposition of nanocomposites based on poly(vinyl alcohol)/thermoplastic starch, as intercalated hybrids, has been established. The changes in the decomposition products distribution and their evolution have been investigated by coupled thermogravimetric analysis, Fourier transform infrared spectroscopy, and mass spectrometry. Detailed analysis of the in situ vapor phase showed that the poly(vinyl alcohol)/starch/clay nanocomposites display a completely different distribution pattern of degradation product, depending on nanoclay content. By in situ vapor phase FTIR and MS spectroscopic techniques, both decomposition compounds of the constituent polymers and some new ones, depending on the nanoparticles content, are identified. The effect of the increase in nanoparticles content consists mainly in variation of some volatile compounds evolution, such as formic acid, water, formaldehyde, propionic acid, methanol, acetic acid carbon dioxide, benzene, etc., which in the case of nanocomposites is very complex. Thus, a content of 2–4 wt% organically-modified montmorillonite hinders the decomposition of the poly(vinyl alcohol)/starch blend. Both characteristic temperature of evolution of the main compounds increases by increasing its content and evolution starting time is delayed; while the untreated nanoclay acts like a catalyst, which decreases characteristic temperatures and evolution time with increasing its content. The temperature dependence of the maximum evolution rate of various compounds on the nanoclay content is very complex as, in the case of nanocomposites, of both primary and secondary reactions and transport phenomena occur simultaneously. Generally, this behavior is related to the dispersion of nanoclays in the polymeric matrix.     

Interaction of silicon-based quantum dots with gibel carp liver: oxidative and structural modifications

Quantum dots (QDs) interaction with living organisms is of central interest due to their various biological and medical applications. One of the most important mechanisms proposed for various silicon nanoparticle-mediated toxicity is oxidative stress. We investigated the basic processes of cellular damage by oxidative stress and tissue injury following QD accumulation in the gibel carp liver after intraperitoneal injection of a single dose of 2 mg/kg body weight Si/SiO₂ QDs after 1, 3, and 7 days from their administration.QDs gradual accumulation was highlighted by fluorescence microscopy, and subsequent histological changes in the hepatic tissue were noted. After 1 and 3 days, QD-treated fish showed an increased number of macrophage clusters and fibrosis, while hepatocyte basophilia and isolated hepatolytic microlesions were observed only after substantial QDs accumulation in the liver parenchyma, at 7 days after IP injection.Induction of oxidative stress in fish liver was revealed by the formation of malondialdehyde and advanced oxidation protein products, as well as a decrease in protein thiol groups and reduced glutathione levels. The liver enzymatic antioxidant defense was modulated to maintain the redox status in response to the changes initiated by Si/SiO₂ QDs. So, catalase and glutathione peroxidase activities were upregulated starting from the first day after injection, while the activity of superoxide dismutase increased only after 7 days. The oxidative damage that still occurred may impair the activity of more sensitive enzymes. A significant inhibition in glucose-6-phosphate dehydrogenase and glutathione-S-transferase activity was noted, while glutathione reductase remained unaltered.Taking into account that the reduced glutathione level had a deep decline and the level of lipid peroxidation products remained highly increased in the time interval we studied, it appears that the liver antioxidant defense of Carassius gibelio does not counteract the oxidative stress induced 7 days after silicon-based QDs exposure in an efficient manner.     

Congestion Pricing: Is a Load Flow-Based Pricing Approach Appropriate?

The move toward open markets and unbundling of transmission services has resulted in the need to assess the impact of a particular generator or load on the power system. The Line Flow Splitting method proposed here—which splits a given load flow into individual consumer load flows and allocates the ensuing congestion costs by extent of use—may serve as a load-flow-based cost allocation concept for congestion management.     

Pursuit and adjustment of goals during unemployment: The role of age.

This longitudinal study investigated the predictive value of 2 self-regulatory processes (goal pursuit and goal adjustment) on mental health and reemployment success over a period of 8 months. A total of 87 unemployed job seekers participated in this study. There is some evidence that age moderated the relationship between goal pursuit and goal adjustment with mental health and reemployment success. Contrary to expectations, goal pursuit was positively related to mental health for relatively older individuals. The authors found no effects of goal adjustment on mental health. However, as expected, goal adjustment had a negative relationship with reemployment success for relatively younger individuals. The authors found no moderator effects of age on the relationship between goal pursuit and reemployment success. Thus, the study revealed different relationships between self-regulatory processes and mental health as well as reemployment success for younger and older individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structure from Motion: Beyond the Epipolar Constraint

The classic approach to structure from motion entails a clear separation between motion estimation and structure estimation and between two-dimensional (2D) and three-dimensional (3D) information. For the recovery of the rigid transformation between different views only 2D image measurements are used. To have available enough information, most existing techniques are based on the intermediate computation of optical flow which, however, poses a problem at the locations of depth discontinuities. If we knew where depth discontinuities were, we could (using a multitude of approaches based on smoothness constraints) accurately estimate flow values for image patches corresponding to smooth scene patches; but to know the discontinuities requires solving the structure from motion problem first. This paper introduces a novel approach to structure from motion which addresses the processes of smoothing, 3D motion and structure estimation in a synergistic manner. It provides an algorithm for estimating the transformation between two views obtained by either a calibrated or uncalibrated camera. The results of the estimation are then utilized to perform a reconstruction of the scene from a short sequence of images.The technique is based on constraints on image derivatives which involve the 3D motion and shape of the scene, leading to a geometric and statistical estimation problem. The interaction between 3D motion and shape allows us to estimate the 3D motion while at the same time segmenting the scene. If we use a wrong 3D motion estimate to compute depth, we obtain a distorted version of the depth function. The distortion, however, is such that the worse the motion estimate, the more likely we are to obtain depth estimates that vary locally more than the correct ones. Since local variability of depth is due either to the existence of a discontinuity or to a wrong 3D motion estimate, being able to differentiate between these two cases provides the correct motion, which yields the least varying estimated depth as well as the image locations of scene discontinuities. We analyze the new constraints, show their relationship to the minimization of the epipolar constraint, and present experimental results using real image sequences that indicate the robustness of the method.     

Passive navigation as a pattern recognition problem

The most basic visual capabilities found in living organisms are based on motion. Machine vision, of course, does not have to copy animal vision, but the existence of reliably functioning vision modules in nature gives us some reason to believe that it is possible for an artificial system to work in the same or a similar way. In this article it is argued that many navigational capabilities can be formulated as pattern recognition problems. An appropriate retinotopic representation of the image would make it possible to extract the information necessary to solve motion-related tasks through the recognition of a set of locations on the retina. This argument is illustrated by introducing a representation of image motion by which an observer's egomotion could be derived from information globally encoded in the image-motion field. In the past, the problem of determining a system's own motion from dynamic imagery has been considered as one of the classical visual reconstruction problems, wherein local constraints have been employed to compute from exact 2-D image measurements (correspondence, optical flow) the relative 3-D motion and structure of the scene in view. The approach introduced here is based on new global constraints defined on local normal-flow measurements—the spatio-temporal derivatives of the image-intensity function. Classifications are based on orientations of normal-flow vectors, which allows selection of vectors that form global patterns in the image plane. The position of these patterns is related to the 3-D motion of the observer, and their localization provides the axis of rotation and the direction of translation. The constraints introduced are utilized in algorithmic procedures formulated as search techniques. These procedures are very stable, since they are not affected by small perturbations in the image measurements. As a matter of fact, the solution to the two directions of translation and rotation is not affected, as long as the measurement of the sign of the normal flow is correct.Part of this work was accomplished while the author was visiting the Royal Institute of Technology, Stockholm, Sweden. The research was supported in part by ARPA, ONR, and Swedish National Science Foundation.     

Terahertz Heterodyne Array Receivers for Astronomy

Journal of Infrared, Millimeter, and Terahertz Waves - We review the development of multi-pixel heterodyne receivers for astronomical research in the submillimeter and terahertz spectral domains....     

Carbonylation of chloromethylated polystyrene resins with NaCo(CO)4 in phase-transfer catalysis

Summary The carbonylation of Chloromethylated and partial quaternizated Chloromethylated polystyrene resins with cobalt tetracarbonyl anion in phase-transfer conditions is described. Dedicated to Prof. C. I. Simionescu on his 65th birthday     

A user-friendly interface to Kendrick's DUAL code

For the well-known stochastic quadratic linear programming problem, the coding of Kendrick is embedded into a user-friendly sequence of interactively used input-generator-optimization-output-generator programs. All three codes are in FORTRAN 77 and implemented on a small mainframe UNIVAC 1180 computer. Some illustrations are given for the ease of use.