Enhancement of electromechanical properties of natural rubber by adding barium titanate filler: An electro-mechanical study

Natural rubber is one of the most potential electro-active polymers for sensors, actuators, and energy harvesting applications. Enhancing the characteristic properties of polymers by reinforcing with fillers that possess multifunctional attributes have attracted considerable attention. In the present study, barium titanate reinforced natural rubber composite is prepared by using two-roll mill mixing. Afterwards, mechanical, electrical, and electromechanical properties of the composites are extensively analyzed by reinforcing different amounts of barium titanate into the matrix of natural rubber. The fabricated dielectric composite shows excellent properties such as high dielectric constant, low dielectric losses, high dielectric breakdown strength, and extreme stretchability. It is observed that as the filler loading reaches the value of 11 parts per hundred rubber (phr), maximum agglomeration of the particles occurs. Maximum stretchability and highest ratio of dielectric constant to elastic modulus are obtained at 8 phr of barium titanate fillers and at the loading, a maximum actuation strain of 11.24% is achieved. This study provides a simple, economical, and effective method for preparing enhanced mechanical, electrical, and electromechanical properties of natural rubber composites, facilitating the wide applications of dielectric materials as actuators and generators.     

Parsing human skeletons in an operating room

Multiple human pose estimation is an important yet challenging problem. In an operating room (OR) environment, the 3D body poses of surgeons and medical staff can provide important clues for surgical workflow analysis. For that purpose, we propose an algorithm for localizing and recovering body poses of multiple human in an OR environment under a multi-camera setup. Our model builds on 3D Pictorial Structures and 2D body part localization across all camera views, using convolutional neural networks (ConvNets). To evaluate our algorithm, we introduce a dataset captured in a real OR environment. Our dataset is unique, challenging and publicly available with annotated ground truths. Our proposed algorithm yields to promising pose estimation results on this dataset.     

Inhibition of N-linked glycosylation results in retention of intracellular apo[a] in hepatoma cells, although nonglycosylated and immature forms of apolipoprotein[a] are competent to associate with apolipoprotein B-100 in vitro

Apolipoprotein[a] (apo[a]) is a highly polymorphic glycoprotein that forms a covalent complex with apolipoprotein B-100 (apoB-100), producing a lipoprotein species referred to as lipoprotein[a] (Lp[a]). We have studied the effects of alterations in glycosylation of apo[a] on its intracellular processing and secretion as well as its ability to associate with low density lipoprotein (LDL) apoB-100. HepG2 cells transfected with a 6 kringle IV (6 K-IV) apo[a] minigene were treated with tunicamycin, an inhibitor of N-linked glycosylation, which eliminated apo[a]-B-100 complexes from the media. Tunicamycin treatment also reduced secretion of the 6 K-IV apo[a] protein from transfected McA-RH7777 cells by approximately 50%, but completely eliminated secretion of apo[a] species containing 9 and 17 K-IV repeats. Mixing experiments, performed with radiolabeled media (+/-tunicamycin) from transfected McA-RH7777 cells, demonstrated no alteration in the extent of association of apo[a] with human LDL. Similar mixing experiments using culture media from glycosylation-defective mutant chinese hamster ovary (CHO) cells transfected with the same apo[a] minigene showed identical results. Apo[a] secretion was demonstrated in all mutant cell lines in the absence of either N- or O-linked (or both) glycosylation. The mechanisms underlying the reduced secretion of apo[a] from transfected hepatoma cells were examined by pulse-chase radiolabeling and apo[a] immunoprecipitation. Tunicamycin treatment altered the efficiency of precursor apo[a] processing from the ER by increasing its ER retention time. The increased accumulation of precursor apo[a] in the ER was associated with alterations in the kinetics of association with two resident endoplasmic reticulum (ER) chaperone proteins, calnexin and BiP. These findings suggest that the glycosylation state and size of apo[a] appear to play a role in regulating its efficient exit from the endoplasmic reticulum. However, neither N- nor O-linked glycosylation of apo[a] exerts a major regulatory role in its covalent association with apoB-100.     

Intraoperative laparoscope augmentation for port placement and resection planning in minimally invasive liver resection

In recent years, an increasing number of liver tumor indications were treated by minimally invasive laparoscopic resection. Besides the restricted view, two major intraoperative issues in laparoscopic liver resection are the optimal planning of ports as well as the enhanced visualization of (hidden) vessels, which supply the tumorous liver segment and thus need to be divided (e.g., clipped) prior to the resection. We propose an intuitive and precise method to plan the placement of ports. Preoperatively, self-adhesive fiducials are affixed to the patient's skin and a computed tomography (CT) data set is acquired while contrasting the liver vessels. Immediately prior to the intervention, the laparoscope is moved around these fiducials, which are automatically reconstructed to register the patient to its preoperative imaging data set. This enables the simulation of a camera flight through the patient's interior along the laparoscope's or instruments' axes to easily validate potential ports. Intraoperatively, surgeons need to update their surgical planning based on actual patient data after organ deformations mainly caused by application of carbon dioxide pneumoperitoneum. Therefore, preoperative imaging data can hardly be used. Instead, we propose to use an optically tracked mobile C-arm providing cone-beam CT imaging capability intraoperatively. After patient positioning, port placement, and carbon dioxide insufflation, the liver vessels are contrasted and a 3-D volume is reconstructed during patient exhalation. Without any further need for patient registration, the reconstructed volume can be directly augmented on the live laparoscope video, since prior calibration enables both the volume and the laparoscope to be positioned and oriented in the tracking coordinate frame. The augmentation provides the surgeon with advanced visual aid for the localization of veins, arteries, and bile ducts to be divided or sealed.     

Culm Morphological Traits Contributing to Lodging Resistance in First Generation NERICA Cultivars Under Foliar Application of Orthosilicic Acid Fertilizer

Silicon - Lodging resistance in upland rice requires adequate knowledge of the mechanical basis of culm morphological traits (CMTs) with potential for improved structural integrity under...     

The Critical Sets of Lines for Camera Displacement Estimation: A Mixed Euclidean-Projective and Constructive Approach

The problem of the recovery of the motion, and the structure from motion is relevant to many computer vision applications. Many algorithms have been proposed to solve this problem. Some of these use line correspondences. For obvious practical reasons, it is important to study the limitation of such algorithms. In this paper, we are concerned with the problem of recovering the relative displacements of a camera by using line matches in three views. In particular, we want to know whether there exist sets of 3D lines such that no matter how many lines we observe there will always be several solutions to the relative displacement estimation problem. Such sets of lines may be called critical in the sense that they defeat the corresponding algorithm. This question has been studied in detail in the case of point matches by early-century Austrian photogrammeters and, independently, in the mid-seventies and early-eighties by computer vision scientists. The answer lies in the idea of a critical surface.The case of lines has been much less studied. Recently, Buchanan (1992a, 1992b) provided a first analysis of the problem in which he gave a positive answer: there exist critical sets of lines and they are pretty big (² lines). In general these sets are algorithm dependent, for example the critical set of lines for the Liu-Huang algorithm introduced in (Buchanan, 1992a), but Buchanan has shown that there is a critical set that defeats any algorithm. This paper is an attempt to build on his work and extend it in several directions. First, we cast his purely projective analysis in a more euclidean framework better suited to applications and, currently, more familiar to most of the computer vision community. Second, we clearly relate his critical set to those of previously published algorithms, in particular (Liu and Huang, 1988a, 1988b). Third, we provide an effective, i.e., computational, approach for describing these critical sets in terms of simple geometric properties. This has allowed us to scrutinize the structure of the critical sets which we found to be both intricate and beautiful.     

Triple-layer proton exchange membranes based on chitosan biopolymer with reduced methanol crossover for high-performance direct methanol fuel cells application

A novel triple-layer proton exchange membrane comprising two thin layers of structurally modified chitosan, as methanol barrier layers, both sides coated with Nafion^®105 is prepared and tested for high-performance direct methanol fuel cell applications. A tight adherence is detected between layers from SEM and EDX data for the cross-sectional area of the newly designed membrane, which are attributed to high affinity of opposite charged polyelectrolyte layers. Proton conductivity and methanol permeability measurements show improved transport properties for the multi-layer membrane compared to Nafion^®117 with approximately the same thickness. Moreover, direct methanol fuel cell tests reveal higher open circuit voltage, power density output, and overall fuel cell efficiency for the triple-layer membrane than Nafion^®117, especially at concentrated methanol solutions. A power output of 68.10 mW cm^?2 at 5 M methanol feed is supplied using multi-layer membrane, which is found to be about 72% more than that of for Nafion^®117. In addition, fuel cell efficiency for multi-layer membrane is measured about 19.55% and 18.45% at 1 and 5 M methanol concentrations, respectively. Owing to the ability to provide high power output, significantly reduced methanol crossover, ease of preparation and low cost, the triple-layer membrane under study could be considered as a promising polyelectrolyte for high-performance direct methanol fuel cell applications.     

Evaluation of registration methods on thoracic CT: the EMPIRE10 challenge

EMPIRE10 (Evaluation of Methods for Pulmonary Image REgistration 2010) is a public platform for fair and meaningful comparison of registration algorithms which are applied to a database of intrapatient thoracic CT image pairs. Evaluation of nonrigid registration techniques is a nontrivial task. This is compounded by the fact that researchers typically test only on their own data, which varies widely. For this reason, reliable assessment and comparison of different registration algorithms has been virtually impossible in the past. In this work we present the results of the launch phase of EMPIRE10, which comprised the comprehensive evaluation and comparison of 20 individual algorithms from leading academic and industrial research groups. All algorithms are applied to the same set of 30 thoracic CT pairs. Algorithm settings and parameters are chosen by researchers expert in the configuration of their own method and the evaluation is independent, using the same criteria for all participants. All results are published on the EMPIRE10 website (http://empire10.isi.uu.nl). The challenge remains ongoing and open to new participants. Full results from 24 algorithms have been published at the time of writing. This paper details the organization of the challenge, the data and evaluation methods and the outcome of the initial launch with 20 algorithms. The gain in knowledge and future work are discussed.