bluuebunny/crossref_metadata_2025 huggingface dataset:
Indoor Place Classification Using Robot Behavior and Vision Data
Authors: Yi Chuho , Oh Young Ceol , Suh Il Hong , Choi Byung-Uk
Published: May 2012

To realize autonomous navigation of intelligent robots in a variety of settings, analysis and classification of places, and the ability to actively collect information are necessary. In this paper, visual data are organized into an orientation histogram to roughly express input images by extracting and cumulating straight lines according to direction angle. In addition, behavioral data are organized into a behavioral histogram by cumulating motions performed to avoid obstacles encountered while the robot is executing specified behavioral patterns. These visual and behavioral data are utilized as input data, and the probability that a place belongs to a specific class is calculated by designating the places already learnt by the robot as categories. The naïve Bayes classification method is employed, in which the probability is calculated that the input data belong to each specific category, and the category with the highest probability is then selected. The location of the robot is classified by merging the probabilities for visual and behavioral data.

The experimental results are as follows. First, a comparison of behavioral patterns used by the robot to collect data about a place indicates that a rotational behavior pattern provides the best performance. Second, classification performance is more accurate with two types of input data than with a single type of data.
A Fuzzy Obstacle Avoidance Controller Using a Lookup-Table Sharing Method and Its Applications for Mobile Robots
Authors: Kim Jinwook , Kim Yoon-Gu , An Jinung
Published: May 2012

A Lookup-Table (LUT) based design enhances the processing speed of a fuzzy obstacle avoidance controller by reducing the operation time. Also, a LUT sharing method provides efficient ways of reducing the LUT memory size. In order to share the LUT which is used for a fuzzy obstacle avoidance controller, an idea of using a basis function is developed. As applications of the shared LUT-based fuzzy controller, a laser-sensor-based fuzzy controller and an ultrasonic-sensor-based fuzzy controller are introduced in this paper. This paper suggests a LUT sharing method that reduces the LUT buffer size without a significant degradation of the performance. The LUT sharing method makes the buffer size independent of the fuzzy system's complexity. A simulation using MSRDS (Microsoft Robotics Developer Studio) is used to evaluate the proposed method. To investigate the performance of the controller, experiments are carried out using a Pioneer P3-DX with LabVIEW as an integration tool. Although the simulation and experiments show little difference between the fully valued LUT-based method and the LUT sharing method in terms of the operation time, the LUT sharing method reduces almost 95% of the full-valued LUT-based buffer size.
Motion Planning Using an Impact-Based Hybrid Control for Trajectory Generation in Adaptive Walking
Authors: Asif Umar , Iqbal Javaid
Published: May 2012

This paper aims to solve a major drawback of walking robots i.e. their inability to react to environmental disturbances while navigating in natural rough terrains. This problem is reduced here by suggesting the use of a hybrid force-position control based trajectory generation with the impact dynamics into consideration that compensates for the stability variations, thus helping the robot react stably in the face of environmental disturbances. As a consequence, the proposed impact-based hybrid control helps the robot achieve better and stable motion planning than conventional position-based control algorithms. Dynamic simulations and real world outdoor experiments performed on a six legged hexapod robot show a relevant improvement in the robot locomotion.
A Robotic System with a Hybrid Motion Cueing Controller for Inertia Tensor Approximation in Micro-Manipulations
Authors: Asif Umar , Iqbal Javaid
Published: May 2012

This paper summarizes the development of a robotic system for the approximation of inertia tensor of micro-sized rigid bodies. We described the design and computer-based simulation of a 6-DOF motion platform in our earlier work [ 32 ] that benefits from an anthropological serial manipulator design. In [ 32 ] we emphasized that, in contrast to a standard configuration based on linear actuators, a mechanism with actuator design inspired from an anthropological kinematic structure offers relatively a larger motion envelope and higher dexterity making it a viable motion platform for micromanipulations. After having described the basic design and kinematic analysis of our motion platform in [ 32 ], we now aim to propose an advanced motion cueing algorithm for facilitating the identification of inertial parameters at micron-level. The motion cueing algorithm for achieving high fidelity dynamic simulation is described in this paper using a hybrid force-position-based controller. The inertia tensor identification is done by generating a controlled motion on the specimen and measuring the resultant forces and moments to approximate the inertia tensor using rigid body dynamics equations. The paper evaluates the performance of the controller using closed-loop dynamic simulations and validates the significance of the proposed method through experimental results.
Robot-Aided Upper-Limb Rehabilitation Based on Motor Imagery EEG
Authors: Xu Baoguo , Peng Si , Song Aiguo , Yang Renhuan , Pan Lizheng
Published: May 2012

Stroke is a leading cause of disability worldwide. In this paper, a novel robot-assisted rehabilitation system based on motor imagery electroencephalography (EEG) is developed for regular training of neurological rehabilitation for upper limb stroke patients. Firstly, three-dimensional animation was used to guide the patient image the upper limb movement and EEG signals were acquired by EEG amplifier. Secondly, eigenvectors were extracted by harmonic wavelet transform (HWT) and linear discriminant analysis (LDA) classifier was utilized to classify the pattern of the left and right upper limb motor imagery EEG signals. Finally, PC triggered the upper limb rehabilitation robot to perform motor therapy and gave the virtual feedback. Using this robot-assisted upper limb rehabilitation system, the patient's EEG of upper limb movement imagination is translated to control rehabilitation robot directly. Consequently, the proposed rehabilitation system can fully explore the patient's motivation and attention and directly facilitate upper limb post-stroke rehabilitation therapy. Experimental results on unimpaired participants were presented to demonstrate the feasibility of the rehabilitation system. Combining robot-assisted training with motor imagery-based BCI will make future rehabilitation therapy more effective. Clinical testing is still required for further proving this assumption.
Water Dancer II-A: A Non-Tethered Telecontrollable Water Strider Robot
Authors: Wu Licheng , Lian Zhipeng , Yang Guosheng , Ceccarelli Marco
Published: May 2012

Water Strider Robot (WSR) is a kind of bio-inspired micro robot that can stand and move on water surface via surface tension. In this paper, a design method is presented with algorithms for designing driving leg. Structure, control system and software of the robot are also discussed in details. A prototype Water Dancer II-a that is driven with two electric motors is presented as successfully tested in lab. The proposed WSR is tele-controlled with infrared signals and has the capability of turning and speed regulation with features of light tiny volume and low power consumption. Experimental results are reported and discussed to show practical feasibility of the presented WSR prototype. The new results in the paper are related also to the WSR prototype design with a robot body of less than 30 × 30 mm size and with ten leg rods of 90 mm length and 0.2 diameter that are able to provide lifting force for a water walk of the 6.0 grams robot at a forward speed of 20 cm/s or angular velocity of 9 degree/s with two micro DC motors(RoomFlight 4 × 8 mm, 28 Ohm).
The KCLBOT: Exploiting RGB-D Sensor Inputs for Navigation Environment Building and Mobile Robot Localization
Authors: Georgiou Evangelos , Dai Jian , Luck Michael
Published: May 2012

This paper presents an alternative approach to implementing a stereo camera configuration for SLAM. The approach suggested implements a simplified method using a single RGB-D camera sensor mounted on a maneuverable non-holonomic mobile robot, the KCLBOT, used for extracting image feature depth information while maneuvering. Using a defined quadratic equation, based on the calibration of the camera, a depth computation model is derived base on the HSV color space map. Using this methodology it is possible to build navigation environment maps and carry out autonomous mobile robot path following and obstacle avoidance. This paper presents a calculation model which enables the distance estimation using the RGB-D sensor from Microsoft .NET micro framework device. Experimental results are presented to validate the distance estimation methodology.
A Piecewise Acceleration-Optimal and Smooth-Jerk Trajectory Planning Method for Robot Manipulator along a Predefined Path
Authors: Chen Yuan , Li Bing
Published: May 2012

This paper proposes a piecewise acceleration-optimal and smooth-jerk trajectory planning method of robot manipulator. The optimal objective function is given by the weighted sum of two terms having opposite effects: the maximal acceleration and the minimal jerk. Some computing techniques are proposed to determine the optimal solution. These techniques take both the time intervals between two interpolation points and the control points of B-spline function as optimal variables, redefine the kinematic constraints as the constraints of optimal variables, and reformulate the objective function in matrix form. The feasibility of the optimal method is illustrated by simulation and experimental results with pan mechanism for cooking robot.
Design of Test Tracks for Odometry Calibration of Wheeled Mobile Robots
Authors: Jung Changbae , Chung Woojin
Published: May 2012

Pose estimation for mobile robots depends basically on accurate odometry information. Odometry from the wheel's encoder is widely used for simple and inexpensive implementation. As the travel distance increases, odometry suffers from kinematic modeling errors regarding the wheels. Therefore, in order to improve the odometry accuracy, it is necessary that systematic errors be calibrated. The UMBmark test is a practical and useful scheme for calibrating the systematic errors of two-wheeled mobile robots. However, the square path track size used in the test has not been validated. A consideration of the calibration equations, experimental conditions, and modeling errors is essential to improve the calibration accuracy. In this paper, we analyze the effect on calibration performance of the approximation errors of calibration equations and nonsystematic errors under experimental conditions. Then, we propose a test track size for improving the accuracy of odometry calibration. From simulation and experimental results, we show that the proposed test track size significantly improves the calibration accuracy of odometry under a normal range of kinematic modeling errors for robots.
Managing Food Quality Risk in Global Supply Chain: A Risk Management Framework
Authors: Chavez Pablo Jose Arevalo , Seow Christopher
Published: May 2012

Today, the food sector is one of the sectors most vulnerable to intentional contamination by debilitating agents [ 1 ]. Some cases of contaminated food have indicated that product quality risk is one of the vulnerabilities in the global supply chain. A series of company scandals, affecting reputation and causing the recall of products and increasing costs have hit the food industry. The obvious problem is that even a minor incident in one part of the chain can have disastrous effects on other parts of the supply chain. Thus, risks are transmitted through the chain. Even though the dangers from members in the supply chain are small, the cumulative effect becomes significant. The aim of this study is to propose an integrated supply chain risk management framework for practitioners that can provide directions for how to evaluate food quality risk in the global supply chain. For validating the proposed model in-depth, a case study is conducted on a food SME distributor in Central America. The case study investigates how product quality risks are handled according to the proposed framework.
A Behaviour-Based Architecture for Mapless Navigation Using Vision
Authors: Guzel Mehmet Serdar , Bicker Robert
Published: May 2012

Autonomous robots operating in an unknown and uncertain environment must be able to cope with dynamic changes to that environment. For a mobile robot in a cluttered environment to navigate successfully to a goal while avoiding obstacles is a challenging problem. This paper presents a new behaviour-based architecture design for mapless navigation. The architecture is composed of several modules and each module generates behaviours. A novel method, inspired from a visual homing strategy, is adapted to a monocular vision-based system to overcome goal-based navigation problems. A neural network-based obstacle avoidance strategy is designed using a 2-D scanning laser. To evaluate the performance of the proposed architecture, the system has been tested using Microsoft Robotics Studio (MRS), which is a very powerful 3D simulation environment. In addition, real experiments to guide a Pioneer 3-DX mobile robot, equipped with a pan-tilt-zoom camera in a cluttered environment are presented. The analysis of the results allows us to validate the proposed behaviour-based navigation strategy.
Hearing symptoms personal stereos
Authors: Borja Ana Lúcia Vieira de Freitas , da Luz Tiara Santos
Published: May 2012

Introduction: Practical and portable the personal stereos if had become almost indispensable accessories in the day the day. Studies disclose that the portable players of music can cause auditory damages in the long run for who hear music in high volume for a drawn out time.

Objective: to verify the prevalence of auditory symptoms in users of amplified players and to know its habits of use

Method: Observational prospective study of transversal cut carried through in three institutions of education of the city of Salvador BA, being two of public net and one of the private net. 400 students had answered to the questionnaire, of both the sex, between 14 and 30 years that had related the habit to use personal stereos.

Results: The symptoms most prevalent had been hyperacusis (43.5%), auricular fullness (30.5%) and humming (27.5), being that the humming is the symptom most present in the population youngest. How much to the daily habits: 62.3% frequent use, 57% in raised intensities, 34% in drawn out periods. An inverse relation between exposition time was verified and the band of age (p = 0,000) and direct with the prevalence of the humming.

Conclusion: Although to admit to have knowledge on the damages that the exposition the sound of high intensity can cause the hearing, the daily habits of the young evidence the inadequate use of the portable stereos characterized by long periods of exposition, raised intensities, frequent use and preference for the insertion phones. The high prevalence of symptoms after the use suggests a bigger risk for the hearing of these young.
Prevalence of auditory changes in newborns in a teaching hospital
Authors: Barbosa Maria Alves , Guimarães Valeriana de Castro
Published: May 2012

Introduction: The precocious diagnosis and the intervention in the deafness are of basic importance in the infantile development. The loss auditory and more prevalent than other joined riots to the birth.

Objective: Esteem the prevalence of auditory alterations in just-born in a hospital school.

Method: Prospective transversal study that evaluated 226 just-been born, been born in a public hospital, between May of 2008 the May of 2009.

Results: Of the 226 screened, 46 (20.4%) had presented absence of emissions, having been directed for the second emission. Of the 26 (56.5%) children who had appeared in the retest, 8 (30.8%) had remained with absence and had been directed to the Otolaryngologist. Five (55.5%) had appeared and had been examined by the doctor. Of these, 3 (75.0%) had presented normal otoscopy, being directed for evaluation of the Evoked Potential Auditory of Brainstem (PEATE). Of the total of studied children, 198 (87.6%) had had presence of emissions in one of the tests and, 2 (0.9%) with deafness diagnosis.

Conclusion: The prevalence of auditory alterations in the studied population was of 0,9%. The study it offers given excellent epidemiologists and it presents the first report on the subject, supplying resulted preliminary future implantation and development of a program of neonatal auditory selection.
Nanocomposite preparation by thermal decomposition of [Ag(hfac)(COD)] in amorphous polystyrene
Authors: Carotenuto G. , Palomba M. , Nicolais L.
Published: May 2012

A simple technique to prepare plastic color filters based on the surface plasmon resonance of silver nanoparticles has been developed. In particular, silver/polystyrene nanocomposite has been prepared by dissolving silver 1,5‐cyclooctadiene‐hexafluoroacetylacetonate in amorphous polystyrene, and the obtained solid solution was heated for ca. 10 s at a convenient temperature (180°C). In these conditions, the metal precursor decomposes and produces silver atoms that diffuse into the polymeric matrix and clusterize, leading to the formation of a contact‐free dispersion of silver nanoparticles. The resulting films have been characterized by large‐angle X‐ray powder diffraction, transmission electron microscopy, and UV–vis spectroscopy. © 2012 Wiley Periodicals, Inc. Adv Polym Techn 31: 242–245, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21278
PROCESSING THERMOPLASTIC MATRIX TOWPREGS BY PULTRUSION
Authors: Nunes J. P. , Silva J. F. , Novo P. J.
Published: May 2012

In the work reported herein, glass fiber reinforced polypropylene towpregs, produced continuously at different processing conditions in a dry powder coating equipment (towpregger), were processed into final composite parts in a specially developed prototype pultrusion equipment. The influence of the towpregger fiber pull speed and the furnace temperature on the polymer content of the final towpregs was determined. The towpregs' quality was also assessed using optical microscopy and scanning electron microscopy. They were then processed into composite profiles in the pultrusion machine, and the influence of the pull speed and dies' temperatures on their mechanical and other relevant physical properties was studied. Finally, the best processing window and the optimization of the final composite profiles are discussed. © 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E306–E312, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21279
Nasal septal deviation in a mediaeval population
Authors: Mays Simon
Published: May 2012

In modern populations, there is evidence that nasal septal deviation (NSD) may be associated with maxillary sinusitis, and that those with NSD may differ in craniofacial morphology from those without or with less severe NSD. Whether these associations hold true for earlier populations has yet to be investigated. The current work is a step toward remedying this. The study group comes from a mediaeval English archaeological site. NSD was quantified using image analysis. Maxillary sinusitis was identified from new bone formation in the antrum. Cranial morphology was assessed using standard craniometric measurements. The results provided no evidence for a relationship between NSD and maxillary sinus disease. NSD was associated with reduced measures of upper facial height, suggesting decoupling of growth in vertical height of the nasal septum and the bony structures surrounding it. Am J Phys Anthropol 148:319–326, 2012. © 2012 Wiley Periodicals, Inc.
Curcumin – vom Molekül zur biologischen Wirkung
Authors: Esatbeyoglu Tuba , Huebbe Patricia , Ernst Insa M. A. , Chin Dawn , Wagner Anika E. , Rimbach Gerald
Published: May 2012

Curcuma (Gelbwurzel) wird traditionell als Würzmittel für Lebensmittel eingesetzt. Curcumin ist ein wichtiger Bestandteil des Currypulvers und verleiht dem Pulver seine charakteristische Farbe. Aufgrund seiner intensiven gelben Farbe wird Curcuma bzw. Curcumin (Zusatzstoff E100) auch zum Färben von Lebensmitteln (z. B. Senf) verwendet. Curcuma enthält die Curcuminoide Curcumin, Demethoxycurcumin und Bisdemethoxycurcumin. In jüngster Zeit werden vermehrt gesundheitsfördernde Eigenschaften (Neuroprotektion, Chemo‐ bzw. Krebsprävention) von Curcuminoiden diskutiert. Curcuminoide induzieren im Organismus endogene antioxidative Schutzsysteme und wirken entzündungshemmend. Curcuminoide beeinflussen die Genexpression sowie epigenetische Regulationsmechanismen. Synthetische Curcumin‐Analoga zeigen zum Teil biologische Wirkungen. Dieser Aufsatz beschreibt die Entwicklung von Curcuma vom “traditionellen” Würz‐ und Färbemittel zum “modernen” biologischen Regulator.
Hydrogen‐Abstraction Reactivity Patterns from A to Y: The Valence Bond Way
Authors: Lai Wenzhen , Li Chunsen , Chen Hui , Shaik Sason
Published: May 2012

“Give us insight, not numbers” was Coulson’s admonition to theoretical chemists. This Review shows that the valence bond (VB)‐model provides insights and some good numbers for one of the fundamental reactions in nature, the hydrogen‐atom transfer (HAT). The VB model is applied to over 50 reactions from the simplest H + H2 process, to P450 hydroxylations and H‐transfers among closed‐shell molecules; for each system the barriers are estimated from raw data. The model creates a bridge to the Marcus equation and shows that H‐atom abstraction by a closed‐shell molecule requires a higher barrier owing to the additional promotion energy needed to prepare the abstractor for H‐abstraction. Under certain conditions, a closed‐shell abstractor can bypass this penalty through a proton‐coupled electron transfer (PCET) mechanism. The VB model links the HAT and PCET mechanisms conceptually and shows the consequences that this linking has for H‐abstraction reactivity.
Importance of pressure drop in divided wall distillation column
Authors: Sangal Vikas Kumar , Bichalu L. , Kumar Vineet , Mishra Indra Mani
Published: May 2012

Pressure drop calculations are extensively used for finding tray spacing at the time of designing a column, but these are rarely performed for the simulation purposes as a minor change in pressure (from condenser to reboiler) has insignificant effect on the vapour–liquid equilibrium. However, pressure difference plays an important role in deciding vapour and liquid flow rate across a tray (or trays), particularly in case of interconnected or divided wall distillation column (DWC). In case of a DWC, the feasible vapour split ratio below the divided wall section is naturally adjusted in such a way that the pressure drops in the two parallel branches of the DWC are equal. In the present work, simulation of a DWC using the MultiFrac model of aspen plusTM (Aspen Technology, Inc., Burlington, MA, USA) was carried out to study the feasible vapour split as a function of reflux ratio and liquid split ratio. The results are interesting in that they show a little effect of liquid split ratio on the feasible vapour split ratio and significantly different pressure profiles in two sides of the DWC. It was also found that the variation in vapour flow rate leads to a large variation in the concentration profile. These results indicate that the pressure drop may be one of the key parameters that should be considered for the optimal design and control of a DWC. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.
Comparison of the effects of wettability alteration and IFT reduction on oil recovery in carbonate reservoirs
Authors: Sheng James J.
Published: May 2012

Injection of chemicals in a carbonate reservoir may change wettability and reduce interfacial tension (IFT). The question is how much each mechanism contributes to the increase in oil recovery. There is lack of such information in the literature. The information is very important because it will guide us to select which chemicals to use, as some chemicals can effectively reduce IFT, whereas others can change wettability.

This paper aims to compare the effects of different mechanisms in oil recovery related to chemical enhanced oil recovery (EOR) . Particularly, we compare the effects of wettability alteration and IFT reduction. Numerical simulation models are used. Our results show that wettability alteration plays important roles when IFT is high, and it is effective in the early time. IFT plays very important roles with or without wettability alteration and is effective during the entire process. Note that the matrix permeability is reasonably high so that the fluids can be redistributed. The implication is that anionic surfactants are preferred to cationic surfactants in chemical EOR, as the former are generally used to reduce IFT, whereas the latter are used to change wettability. Other observations are that in surfactant‐induced wettability alteration with low IFT, gravity drive is a very important mechanism. Molecular diffusion of chemicals affects oil recovery rate in the early time, but not ultimate oil recovery. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.
Kinetics of photocatalytic degradation of atrazine on molecularly imprinted titania film
Authors: Zhang Chunjing , Yang Zhengpeng , Zhang Chunxiao , Sun Yukun
Published: May 2012

A titania film imprinted by atrazine molecule at the surface of a quartz crystal was prepared using molecular imprinting and surface sol–gel process. The quartz crystal microbalance technique was employed to in situ investigate the degradation behavior of atrazine on the molecularly imprinted titania film. The obtained results reveal that the molecular imprinting can enhance degradation of atrazine on titania films, and the degradation rate constants (K) estimated from the in situ frequency measurement is about 0.62 × 10−3 s−1, which is two times higher than that obtained on non‐imprinted titania films. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.
Preparation of photocured azidophenyl‐fish gelatin and its capturing of human epidermal growth factor on titanium plate
Authors: Park Shin‐Hye , Seo Si‐Yoong , Kang Jeong‐Hwa , Ito Yoshihiro , Son Tae‐Il
Published: May 2012

Protein immobilization is important in various medical fields that involve the use of metal. Titanium has been often utilized in various medical fields based on its biocompatibility and noncytotoxicity. However, as an unmodified titanium surface is not suitable, dopamine must be coated on the titanium surface. Among gelatin sources, fish gelatin is more suitable in the human body and does not pose serious side effects compared to porcine gelatin. Therefore, a photoreactive azidophenyl group was introduced to fish gelatin to create azidophenyl‐fish gelatin (azidophenyl‐f.gel). The azidophenyl group was analyzed by 1H‐NMR, UV spectroscopy, and gel permeation chromatography. The curing ratio of azidophenyl‐f.gel was measured using a micropatterning plate. Epidermal growth factor immobilization ability, cytotoxicity, and cell attachment tests were performed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effect of seed characteristics on morphology development in poly(n‐butyl acrylate)‐poly(n‐butyl methacrylate) core‐shell dispersions
Authors: Suresh Kattimuttathu I. , Bartsch Eckhard
Published: May 2012

This article reports on the influence of synthesis characteristics such as seed cross linking, particle‐size distribution (PSD), and surfactant in the seeded emulsion polymerization of n‐butyl acrylate–butyl methacrylate core‐shell systems. These systems were studied using a combination of techniques such as light scattering (static and dynamic), asymmetric field flow fractionation coupled with multiangle laser light scattering and transmission electron microscopy. Complimentary data, obtained from static light scattering and electron microscopy studies, on the effect of seed crosslinking on morphology development reveals that the presence of a crosslinked seed favors the formation of nonequilibrium core‐shell morphology. For uncrosslinked seeds occluded structures were present with a diffuse boundary between the core and the shell. In both cases, i.e., with or without surfactant, a monomodal PSD was observed for the core‐shell systems and the relative size polydispersity and the shape of the seed PSD were retained. Use of surfactant was found to broaden the PSD but did not seem to affect the formation core‐shell morphology. The study also shows the influence of crosslinked seeds on the film properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Compatibilization of natural rubber/high density polyethylene thermoplastic vulcanizate with graphene oxide through ultrasonically assisted latex mixing
Authors: Yan Ning , Xia Hesheng , Wu Jinkui , Zhan Yanhu , Fei Guoxia , Chen Chen
Published: May 2012

Natural rubber (NR)/high density polyethylene (HDPE) thermoplastic vulcanizate was compatibilized with graphene oxide (GO) by an ultrasonically assisted latex mixing process (ULM). GO was dispersed into NR latex by ultrasonic irradiation and followed by latex coagulation to obtain the NR/GO master‐batch, which was further mixed and diluted with HDPE and NR via a dynamic vulcanization process to obtain the NR/HDPE/GO hybrid composites. It was found that the stacked GO platelets were successfully exfoliated by the ULM process and have good compatibilization efficiency for the immiscible NR and HDPE. A smaller discrete NR domain was observed in NR/HDPE blend in the presence of the GO. Moreover, the stacked GO platelets enhance the interfacial adhesion and phase compatibility, which results in an increase in mechanical property of NR/HDPE blends. Compared to the NR/HDPE blend, the tensile strength and tensile modulus at 300% strain for NR/HDPE/ (1.5 phr) GO blend were increased by ∼ 27% and ∼ 24%, respectively. The exfoliated GO can act as both the effective reinforcing filler and compatibilizer in the immiscible NR/HDPE blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Properties of polyimide hybrids with mixed metal oxide
Authors: Lu Hsu‐Tung , Huang Shih‐Liang , Tseng I‐Hsiang , Lin Yin‐Kai , Tsai Mei‐Hui
Published: May 2012

Polyimide/silica–titania (PI/SiO2–TiO2) hybrid films were prepared via an in situ sol–gel process. The PI precursor, poly(amic acid) (PAA), which contains 2,2'‐bis[4‐(4‐aminophenoxy)‐phenyl]propane (p‐BAPPP), 3,3',4,4'‐ benzophenetetracarboxylic anhydride (BTDA) and 3‐aminopropyltrimethoxysilane (APrTMOS), was first synthesized; this was followed by the addition of phenyltrimethoxysilane (PTMS) and/or tetraethyl orthotitanate (Ti(OEt)4) to fabricate PI/SiO2–TiO2 films. The relative content of SiO2 to TiO2 has remarkable effects on the crosslink structure and resultant properties of the hybrids. XPS results confirm that the amount of Si on the surface of the hybrids is higher than that in the bulk. The distribution of Ti in the hybrid films is contrary to the above trend because of the formation of three‐dimensional SiOSi, SiOTi, and TiOTi networks. The SiO2 content of the hybrids containing only silica significantly affects their refractive index, contact angle, and dielectric constant. The films with added PTMS show higher contact angles than pure PI because nonpolar segments, C2H6 or benzene groups, tend to distribute on the surface. Upon the addition of (Ti(OEt)4), some hydrophilic segments on the surface of the hybrids are induced because of the formation of a crosslinked structure. The denser crosslinked molecular structure, and consequently lower CTE and higher Tg are obtained from hybrids containing more TiO2. By comparing the above properties and flexibility, the best composition of metal oxides (SiO2/TiO2) in hybrids is 20/80. That is, an optimum ratio of metal oxides in PI hybrids induces superior properties for advanced practical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Side effects in the application of polyamide 6 barrier materials for fuel tanks
Authors: Chernev Boril S. , Eder Gabriele C.
Published: May 2012

To reduce the pollution of air by minimizing evaporative emissions from fuel tanks, new plastic fuel tanks made of materials with excellent barrier properties have to be developed. Single‐layer polyamide 6 tanks are one option to meet the requested low‐hydrocarbon permeation rates for motorcycle vehicle tanks. Recently, some problems with respect to deposits in polyamide 6 tanks, blocked nozzles, tubing, and gasoline filters were observed. Thus, samples (precipitates) were taken from unused tanks after conditioning as well as of used tanks and filters after being in contact with gasoline for some time. By investigating the precipitates and deposits by means of infrared (IR) spectroscopy, the main constituents were identified to be cyclic caprolactam oligomers. Additional investigations on the extracted samples by mass spectroscopy allowed us to attribute specific features of the IR spectra to the individual cyclic oligomers (dimer, trimer, and tetramer). In addition, we could show that the crystalline precipitates and deposits in the fuel systems of used vehicles consist of mixtures of the cyclic dimer, trimer, tetramer, and even pentamer of caprolactam with varying contributions of the individual oligomers in dependence of the history of the part. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
POMA/PMMA blends modified by dye: Spectroscopic and morphological properties
Authors: Pereira N. S. , do Monte A. F. G. , Ceschin A. M. , Sales M. J. A.
Published: May 2012

Poly(o‐methoxyaniline) (POMA), a conductive polymer (CP) well known, was used to prepare blends with poly(methyl methacrylate) (PMMA). Conducting polymer keeps absorbance strength within the PMMA matrix. POMA/PMMA blends presented absorption bands regarding the conducting polymer with different intensities and the main band red shifting. However, POMA/PMMA blends showed no photoluminescence (PL) emission. After the hybridization process of the CP with a photoluminescent dye, 2,1,3‐benzothiadiazole, POMA/PMMA blends showed new optical properties. PL spectra revealed an emission in the range of 500–550 nm, indicating interaction between the dye and the conducting polymer. The presence of the dye modified the morphological properties of the POMA/PMMA blends. New features have appeared on the surface of the blends prepared with higher concentration of hybridized CP. Blends with lower concentrations of hybridized CP showed their surfaces with POMA globules being covered by PMMA. This morphology replaced the globules and “crystals” on the surface of the blends prepared without the dye. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Nucleation effect of hydroxyl‐purified multiwalled carbon nanotubes in poly(p‐phenylene sulfide) composites
Authors: Sheng‐Ling Jiang , Xiao‐Yu Gu , Zhi‐Yuan Zhang
Published: May 2012

To investigate the nucleation effect of hydroxyl‐purified multiwalled carbon nanotubes (MWNTs‐OH) in poly(p‐phenylenesulfide) (PPS), a series of composites were prepared by blending PPS with MWNTs‐OH at 1, 2, and 3 wt %, respectively. Under SEM observation MWNTs‐OH were found homogeneously dispersed in the PPS matrix. DSC thermograms revealed that the enthalpy (ΔHc) of the composites increased with increasing MWNT‐OH content, whereas the crystallization temperature (Tc) decreased progressively. The decrease in Tc was in accordance with the smaller crystallite size determined with WXRD characterization, and the increase in ΔHc was evidenced by FTIR and XPS analyses. The higher ΔHc shows that MWNTs‐OH serves as a nucleating agent, providing sufficiently multiplied sites for crystal growth. The lowering of Tc was attributed not only to MWNTs‐OH network hindrance to PPS chain fusing rearrangement, but also to a poorer affinity between MWNTs‐OH and PPS; both effects coordinately govern Tc of PPS/MWNTs‐OH composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
A new insight into interface widths in binary polymer blends based on ortho‐positronium lifetime studies
Authors: Ramya P. , Ranganathaiah C.
Published: May 2012

The interface widths in two immiscible polymer blend (Poly vinyl chloride (PVC)/Polystyrene (PS)) and PVC/Ethylene Vinyl Acetate (EVA) are determined experimentally using hydrodynamic interaction approach through free volume measurement by positron annihilation lifetime spectroscopy. For comparison, the same study is performed in a miscible blend (Styrene Acrylonitrile (SAN)/Poly Methyl Methacrylate (PMMA)). The interfacial width (Δl) is evaluated from the hydrodynamic interaction (α) based on Kirkwood–Risemann theory and friction coefficient from Stokes equation. Friction at the interface of a binary blend evidences how close the surfaces of the polymer chains come or stay apart which in turn depends on the type of force/interaction at the interface. In this work, we define interface width from a different perspective of Flory–Huggins interaction approach. Measured composition dependent interface widths in the three blends studied clearly demonstrate the sensitivity of the present method. In miscible blend, high friction at the interface results in stronger hydrodynamic interaction and hence smaller interface widths (0.36–1.97 Å), whereas weak or no interaction in immiscible blends produce wider widths (2.81–25.0 Å). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Mechanical and thermal degradation properties of silk from African wild silkmoths
Authors: Teshome Addis , Onyari John M. , Raina Suresh K. , Kabaru Jacques M. , Vollrath Fritz
Published: May 2012

Variations among silk of four African wild silkmoths,Argema mimosae,Anaphe panda,Gonometa postica, andEpiphora bauhiniae, was studied regarding their mechanical properties and thermal degradation behaviors. Cocoon shells and individual degummed fibers were examined using tensile testing, thermogravimetric analysis, and scanning electron microscope (SEM).A. mimosaeandG. posticacocoon shells had marginally higher initial moduli and strains at maximum stress. The stress–strain curves ofBobmyx moriandA. pandadegummed fibers lacked clear yielding points.G. posticafibers had the highest breaking energy (76.4 J/cm3) and breaking strain (41.3%). The ultimate tensile strength was the highest forB. mori(427 MPa). Fiber pull‐out and detachment was predominant in fracture surfaces of both the cocoon shells and the fibers. Wild cocoon shells and degummed fibers had higher temperature for dehydration loss thanB. mori.A. mimosaefibers (11.9%) and G. postica cocoon shells (13.3 %) had the highest weight loss due to dehydration.E. bauhinaecocoon shells andB. morifibers had the highest total weight losses of 97.2 and 93.4%, respectively. The African silks exhibited variations in their mechanical and thermal degradation properties related to their physical and chemical structure and composition. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
A novel route for the synthesis of poly(2‐hydroxyethyl methacrylate) grafted TiO2 nanoparticles via surface thiol‐lactam initiated radical polymerization
Authors: Bach Long Giang , Islam Md. Rafiqul , Seo Sung Yong , Lim Kwon Taek
Published: May 2012

Hybrid nanocomposites of poly(2‐hydroxyethyl methacrylate) (PHEMA) and TiO2 nanoparticles were synthesized via surface thiol‐lactam initiated radical polymerization by following the grafting from strategy. Initially, TiO2 nanoparticles were modified by 3‐mercaptopropyl trimethoxysilane to prepare thiol functionalized TiO2 nanoparticles (TiO2SH). Subsequently, surface initiated polymerization of 2‐hydroxyethyl methacrylate was conducted by using TiO2SH and butyrolactam as an initiating system. The anchoring of PHEMA onto the surface of TiO2 nanoparticles was investigated by FTIR, 1H‐NMR, XPS, TGA, and XRD analyses. The experimental results indicated a strong interaction between PHEMA and TiO2 nanoparticles owing to covalent bonding. The TEM and SEM images of PHEMA‐g‐TiO2 showed that the agglomeration propensity of TiO2 nanoparticles was significantly reduced upon the PHEMA functionalization. The molecular weight and polydispersity index of the cleaved PHEMA from the surface of TiO2 nanocomposites were estimated by GPC analysis. An improved thermal property of the nanocomposites was observed from TGA analysis. PHEMA‐g‐TiO2 nanocomposites were found to be highly dispersible in organic solvents. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Hemocompatibility evaluation of polyurethane film with surface‐grafted poly(ethylene glycol) and carboxymethyl‐chitosan
Authors: Ren Zhenchu , Chen Guangyi , Wei Zhiyong , Sang Lin , Qi Min
Published: May 2012

To improve the hemocompatibility and biocompatibility of polyurethanes (PUs), PU surface was firstly modified by poly(ethylene glycol) PEG through acryloyl chloride and subsequently grafted on carboxymethyl‐chitosan (CMCS). Attenuated total reflection Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy analysis confirmed that carboxyl‐chitosan was grafted onto PUs surface. The surface properties of unmodified and modified PU films were determined and compared by water contact angle assessment. After PEG and CMCS grafting, the surface energy of the PU film was increased. Furthermore, the hemocompatibility of the modified PU films was systematically evaluated by bovine serum albumin (BSA) adsorption, the dynamic blood clotting test, the platelet adhesion test, and the hemolytic test. It appears that BSA adsorption and platelet adhesion were significantly curtailed for the modified PU films. Therefore, the obtained results showed the modified PU film has better hemocompatibility. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Grafting of maleic anhydride onto an ethylene‐propylene‐diene terpolymer and concurrent organoclay nanocomposite preparation in solution and melt
Authors: Krajnc Matjaž , Karger‐Kocsis József , Šebenik Urška
Published: May 2012

The possibility of simultaneous peroxide‐initiated grafting of MAH (maleic anhydride) onto EPDM (ethylene‐propylene‐diene terpolymer) and EPDM/clay nanocomposite synthesis by the solution and melt process is investigated. Montmorillonite organoclay is used. Maleation efficiency is investigated by infrared spectroscopy. Clay exfoliation and the resulting nanocomposite properties are determined by X‐ray diffraction and dynamic mechanical analysis, respectively. Simultaneous grafting and exfoliated nanocomposite synthesis can be carried out in solution and melt. The use of optimal amounts of initiator and MAH is very important. High peroxide initiator concentration causes extensive EPDM crosslinking and scission reactions. High concentration of MAH deteriorates clay exfoliation in melt because of reduced shearing due to MAH addition. The use of low MAH concentration is a straightforward solution if the extent of MAH grafting onto EPDM is not considerably impaired. To overcome this problem, a two step melt compounding process is suggested and tried out. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Covalent immobilization of α‐amylase onto thermally crosslinked electrospun PVA/PAA nanofibrous hybrid membranes
Authors: Baştürk Emre , Demir Serap , Danış Özkan , Kahraman Memet Vezir
Published: May 2012

Poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) nanofibers with the fiber diameter of 100–150 nanometers were fabricated by electrospinning. PVA/PAA nanofibers were crosslinked by heat‐induced esterification and resulting nanofiber mats insoluble in water. α‐Amylase was covalently immobilized onto the PVA/PAA nanofiber surfaces via the activation of amine groups in the presence of 1,1′‐carbonyldiimidazole. The immobilized α‐amylase has more resistance to temperature inactivation than that of the free form and showed maximum activity at 50°C. pH‐dependent activities of the free and immobilized enzymes were also investigated, and it was found that the pH of maximum activity for the free enzyme was 6.5, while for the optimal pH of the immobilized enzyme was 6.0. Reuse studies demonstrated that the immobilized enzyme could reuse 15 times while retaining 81.7% of its activity. Free enzyme lost its activity completely within 15 days. Immobilized enzyme lost only 17.1% of its activity in 30 days. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Habitat use by a freshwater dolphin in the low‐water season
Authors: Braulik Gill T. , Reichert Albert P. , Ehsan Tahir , Khan Samiullah , Northridge Simon P. , Alexander Jason S. , Garstang Richard
Published: May 2012

Many river dolphin populations are most vulnerable during the low‐water season when habitat is limited. Indus River dolphin habitat selection in the dry season was investigated using Generalized Linear Models of dolphin distribution and abundance in relation to physical features of river geomorphology and channel geometry in cross‐section.

Dolphins selected locations in the river with significantly greater mean depth, maximum depth, cross‐sectional area, and hydraulic radius, and significantly narrower river width and a lower degree of braiding than areas where dolphins were absent. They were also recorded with higher frequency at river constrictions and at confluences.

Channel cross‐sectional area was the most important factor affecting dolphin presence and abundance, with the area of water below 1 m in depth exerting the greatest influence. Indus dolphins avoided channels with small cross‐sectional area (<700 m2), presumably owing to the risk of entrapment and reduced foraging opportunities.

Channel geometry had a greater ability to explain dolphin distribution than river geomorphology; however, both analyses indicated similar types of habitat selection. The dolphin–habitat relationships identified in the river geomorphology analysis were scale‐dependent, indicating that dolphin distribution is driven by the occurrence of discrete small‐scale features, such as confluences and constrictions, as well as by broader‐scale habitat complexes.

There are numerous plans to impound or extract more water from the Indus River system. If low‐water season flows are allowed to decrease further, the amount of deeper habitat will decline, there may be insufficient patches of suitable habitat to support the dolphin population through the low‐water season, and dolphins may become isolated within deeper river sections, unable or unwilling to traverse through shallows between favourable patches of habitat.

Copyright © 2012 John Wiley & Sons, Ltd.