bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Study on Automated Cell Nuclei Segmentation Methods for Cytology Pleural Effusion Images
Authors: Win Khin Yadanar , Choomchuay Somsak , Hamamoto Kazuhiko , Raveesunthornkiat Manasanan
Published: September 2018

Automated cell nuclei segmentation is the most crucial step toward the implementation of a computer-aided diagnosis system for cancer cells. Studies on the automated analysis of cytology pleural effusion images are few because of the lack of reliable cell nuclei segmentation methods. Therefore, this paper presents a comparative study of twelve nuclei segmentation methods for cytology pleural effusion images. Each method involves three main steps: preprocessing, segmentation, and postprocessing. The preprocessing and segmentation stages help enhancing the image quality and extracting the nuclei regions from the rest of the image, respectively. The postprocessing stage helps in refining the segmented nuclei and removing false findings. The segmentation methods are quantitatively evaluated for 35 cytology images of pleural effusion by computing five performance metrics. The evaluation results show that the segmentation performances of the Otsu, k-means, mean shift, Chan–Vese, and graph cut methods are 94, 94, 95, 94, and 93%, respectively, with high abnormal nuclei detection rates. The average computational times per image are 1.08, 36.62, 50.18, 330, and 44.03 seconds, respectively. The findings of this study will be useful for current and potential future studies on cytology images of pleural effusion.
Multiple Routes to Oncogenesis Are Promoted by the Human Papillomavirus–Host Protein Network
Authors: Eckhardt Manon , Zhang Wei , Gross Andrew M. , Von Dollen John , Johnson Jeffrey R. , Franks-Skiba Kathleen E. , Swaney Danielle L. , Johnson Tasha L. , Jang Gwendolyn M. , Shah Priya S. , Brand Toni M. , Archambault Jacques , Kreisberg Jason F. , Grandis Jennifer R. , Ideker Trey , Krogan Nevan J.
Published: September 2018

We have mapped a global network of virus–host protein interactions by purification of the complete set of human papillomavirus (HPV) proteins in multiple cell lines followed by mass spectrometry analysis. Integration of this map with tumor genome atlases shows that the virus targets human proteins frequently mutated in HPV− but not HPV+ cancers, providing a unique opportunity to identify novel oncogenic events phenocopied by HPV infection. For example, we find that the NRF2 transcriptional pathway, which protects against oxidative stress, is activated by interaction of the NRF2 regulator KEAP1 with the viral protein E1. We also demonstrate that the L2 HPV protein physically interacts with the RNF20/40 histone ubiquitination complex and promotes tumor cell invasion in an RNF20/40-dependent manner. This combined proteomic and genetic approach provides a systematic means to study the cellular mechanisms hijacked by virally induced cancers.

Significance: In this study, we created a protein–protein interaction network between HPV and human proteins. An integrative analysis of this network and 800 tumor mutation profiles identifies multiple oncogenesis pathways promoted by HPV interactions that phenocopy recurrent mutations in cancer, yielding an expanded definition of HPV oncogenic roles. Cancer Discov; 8(11); 1474–89. ©2018 AACR.

This article is highlighted in the In This Issue feature, p. 1333
Adolescent Inhalant Abuse Results in Adrenal Dysfunction and a Hypermetabolic Phenotype with Persistent Growth Impairments
Authors: Crossin Rose , Andrews Zane B. , Sims Natalie A. , Pang Terence , Mathai Michael , Gooi Jonathan H. , Stefanidis Aneta , Oldfield Brian J. , Lawrence Andrew J. , Duncan Jhodie R.
Published: September 2018

Background/Aims: Abuse of toluene products (e.g., glue-sniffing) primarily occurs during adolescence and has been associated with appetite suppression and weight impairments. However, the metabolic phenotype arising from adolescent inhalant abuse has never been fully characterised, and its persistence during abstinence and underlying mechanisms remain unknown. Methods: Adolescent male Wistar rats (post-natal day 27) were exposed to inhaled toluene (10,000 ppm) (n = 32) or air (n = 48) for 1 h/day, 3 days/week for 4 weeks, followed by 4 weeks of abstinence. Twenty air rats were pair-fed to the toluene group, to differentiate the direct effects of toluene from under-nutrition. Food intake, weight, and growth were monitored. Metabolic hormones were measured after exposure and abstinence periods. Energy expenditure was measured using indirect calorimetry. Adrenal function was assessed using adrenal histology and hormone testing. Results: Inhalant abuse suppressed appetite and increased energy expenditure. Reduced weight gain and growth were observed in both the toluene and pair-fed groups. Compared to the pair-fed group, and despite normalisation of food intake, the suppression of weight and growth for toluene-exposed rats persisted during abstinence. After exposure, toluene-exposed rats had low fasting blood glucose and insulin compared to the air and pair-fed groups. Consistent with adrenal insufficiency, adrenal hypertrophy and increased basal adrenocorticotropic hormone were observed in the toluene-exposed rats, despite normal basal corticosterone levels. Conclusions: Inhalant abuse results in negative energy balance, persistent growth impairment, and endocrine changes suggestive of adrenal insufficiency. We conclude that adrenal insufficiency contributes to the negative energy balance phenotype, potentially presenting a significant additional health risk for inhalant users.
Assessment of Quality and Reliability of Measurements with XBT Sippican T5 and T5/20
Authors: Reseghetti Franco , Cheng Lijing , Borghini Mireno , Yashayaev Igor M. , Raiteri Giancarlo , Zhu Jiang
Published: September 2018

The T5 expendable bathythermographs reach the greatest depth within the current XBT family. Since the early 1970s, in several areas they have been providing a significant part of available temperature profiles below 1000 m and therefore represent an important resource for ocean climate study. In this paper we present new results from laboratory tests of Sippican T5 and T5/20 probes and analyses of more than 350 XBT–CTD matched pairs from our own field trials and the World Ocean Database (WOD), and we propose an improved fall rate equation (coefficients: A = 6.720 ± 0.025 m s−1, B = 0.001 60 ± 0.000 15 m s−2, Offset = 1.00 ± 0.65 m). Possible influences of probe physical characteristics and initial launch conditions on the probe motion have also been investigated with launching height and probe weight being identified as important factors. Analyses also confirm that fall speed and pure temperature error increase with water temperature, as previously reported for other XBT types. The uncertainties in depth and temperature measurements are then calculated. Finally, a new correction for a global T5 dataset is proposed, with an update of the currently available schemes.
A pedagogical case on active learning regarding to Kirchhoff's circuit laws
Authors: Kang Rui , Lin Yixuan , Wang Yuexin , Wu Hao , Wu Minghe , Teng Baohua
Published: September 2018

Kirchhoff’s circuit laws are important basic concepts in many basic disciplines, such as electricity and circuitry. However, in the usual teaching process, teachers often teach this knowledge using some simple examples of analysis and calculation but without deep discussions. As a result, students could not have a deep understanding about these concepts or not apply the concepts on actual problems flexibly. Therefore, passive learning habits are formed. The lack of self-exploration awareness and comprehensive ability would result in a poor learning effect. This paper designs a specific application scene of Kirchhoff’s circuit laws using a multi-channel resistor network. With this application, students can construct the knowledge system autonomously, find the problems proactively, solve the problems timely, and combine the research-based autonomous learning with extracurricular open mutual learning; so, their active learning ability will be promoted to a large extent. Compared with the past teaching methods, this pedagogical case highlights the following advantages of active learning. Firstly, it highlights the process of guiding students to study the object from a small-scale resistor network to a complex and large-scale multi-channel resistor network. Secondly, it embodies the concrete application of calculus knowledge in various basic courses with the help of perfect mathematical deduction. Thirdly, it exercises students’ programming ability by using MATLAB to numerically simulate theoretical results. Finally, this case practices students’ hands-on experimental ability by constructing real resistor circuits and verifying the theory and simulation results. In addition, we get good feedback from students on the teaching effect through the questionnaire survey.
Cities and the Anthropocene: Urban governance for the new era of regenerative cities
Authors: Thomson Giles , Newman Peter
Published: September 2018

The emerging ‘grand challenges’ of climate change, resource scarcity and population growth present a risk nexus to cities in the Anthropocene. This article discusses the potential that rapid urbanisation presents to help mitigate these risks through large-scale transitions if future urban development is delivered using evidence-based policies that promote regenerative urban outcomes (e.g. decarbonising energy, recycling water and waste, generating local food, integrating biodiversity). Observations from an Australian case study are used to describe urban governance approaches capable of supporting regenerative urbanism. The regenerative urbanism concept is associated with macro-scale urban and transport planning that shapes different urban fabrics (walking, transit, automobile), as the underlying infrastructure of each fabric exhibits a different performance, with automobile fabric being the least regenerative. Supporting urban systems based upon regenerative design principles at different scales (macro, meso and micro) can deliver deep and dramatic outcomes for not just reducing the impact of the grand challenges but turning them into regenerative change. In combination, these approaches form the cornerstone of regenerative cities that can address the grand challenges of the Anthropocene, while simultaneously improving livability and urban productivity to foster human flourishing.
Imaginations of post-suburbia: Suburban change and imaginative practices in Auckland, New Zealand
Authors: Johnson Cameron , Baker Tom , Collins Francis L
Published: September 2018

Imaginative practices are central to ongoing transformations in the form and function of suburbia. In recent years, urban scholars have focused increasing attention on the concept and process of ‘post-suburbanisation’ to understand contemporary suburbs, yet imaginaries and imaginative practices have been largely absent in their analyses. This paper examines the role of imaginative practices in post-suburban change. Through a case study of Auckland, New Zealand, the paper examines three key domains of imaginative practice – visions, problems and trajectories – implicated in the production of post-suburbia. It argues that understandings of post-suburbanisation will be enhanced by an appreciation of both the material and imaginative dimensions of suburban transformation.
Achieving Effective International Cooperation: How Institutional Formalization Shapes Intergovernmental Negotiations
Authors: Lenz Hartmut
Published: September 2018

This article explores how formalization of institutions and domestic constraints influence the outcomes of international cooperation and negotiation processes—particularly in a regional setting like the European Union (EU) or the Association of Southeast Asian Nations (ASEAN). Examining different forms of institutional setup along the formal‐informal continuum, this study evaluates their impact on the successes and failures of intergovernmental negotiation processes. While some scholars have been vocal about the importance of institutional setting on negotiation outcomes, there has not yet been any systematic analysis of the impact of institutional variations on the actual negotiation process. This project specifies under what conditions domestic actors constrain governments, and how these conditions depend on institutional structures. I analyze the impact of institutional variations, concentrating on negotiation failure and deadlock situations, to form a framework that can differentiate between various bargaining situations and to understand their impact on the possibility to facilitate successful negotiation outcomes. The central argument highlights the need for more nuanced connections between institutional design, domestic constraints, and the level of formalization to understand the likelihood of success or failure of intergovernmental negotiation processes.
Incidence and risk factors of facet joint violation following percutaneous kyphoplasty for osteoporotic vertebral compression fractures
Authors: Li Yao , Wang Xiangyang , Jiang Kaixia , Chen Jiaoxiang , Lin Yan , Wu Yaosen
Published: September 2018

Background

Percutaneous kyphoplasty (PKP) has been widely used to osteoporotic vertebral compression fractures (OVCFs). No previous investigations have reported the incidence and risk factors of facet joint violation (FJV) caused by PKP.

Purpose

To determine the incidence and risk factors of FJV following PKP in patients with OVCFs.

Material and Methods

We reviewed a total of 153 patients who underwent bilateral PKP. Postoperative computed tomography (CT) scans were assessed to determine the degree of FJV owing to invasion by a puncture trocar. Clinical outcomes, including visual analogue scale (VAS) scores and Oswestry Disability Index (ODI) scores, were collected from all patients. Clinical and radiological data were analyzed to identify the risk factors for FJV.

Results

FJV caused by PKP affected 18.9% of patients and 9.6% of facet joints; approximately 3.9% and 5.7% of facet joints were considered to have grade 1 and grade 2 violations, respectively. There were significant differences between the FJV and non-FJV groups in VAS and ODI scores after surgery. Significant differences were found with respect to the facet joint angle (FJA), the pedicle diameter (PD), and the distance from the entry point to the facet joint space (DEF). Multiple logistic regression analysis indicated that an FJA > 55°, a PD < 5 mm, and a DEF < 5 mm were independent risk factors for FJV.

Conclusion

The placement of a puncture trocar can cause FJV in patients with OVCFs and impact clinical outcomes after PKP. Special attention should be given to patients with an FJA > 55°, a PD < 5 mm, and a DEF < 5 mm.
Pyrogenic Silica as a Filler for Elastomeric Materials
Authors: Michel W.
Published: September 2018

Carbon black has been the most important active filler in rubber technology for decades. In recent years, however, the use of silica to produce rubber compounds has been on the increase. In combination with sulfur-containing silanes (e.g. TESP, bis(triethoxysilylpropyl) tetrasulfane, trade name SI69), precipitated silicas now have an established place among the raw materials for the production of abrasion-resistant, elastic and fatigue-resistant elastomeric materials. Less well known, however, is the use of silica products produced by flame hydrolysis, such as Aerosil, which can significantly improve the mechanical properties of many elastomer formulations.
A utilitarian view: A content analysis of agenda-setting effects within popular news coverage of the mobile phone
Authors: Cole Amelia W. , Lovejoy Jennette
Published: September 2018

The mobile phone has changed the human–mobile device relationship, which has given rise to a controversy regarding the neutrality of technological devices. This study seeks to understand how news media portray mobile phone devices using second-level agenda setting that extends the model to the public perception of mobile devices. Conducting a content analysis (N = 630) of two major U.S. newspapers covering the years 1991 to 2015, this study discovered that news articles primarily communicated mobile phones as neutral tools.
Competing Visions: Discursive Articulations of Polish and European Identity after the Eastern Enlargement of the EU
Authors: Góra Magdalena , Zielińska Katarzyna
Published: September 2018

The enlargement of 2004 and 2007 significantly transformed the European Union in political, economic, and social terms. It also challenged the collective identities of Western Europeans as well as each of the newcomers. However, for new members, the prospect of joining a supranational political entity posed a threat to their newly established or regained sovereignty and nationhood. The integration triggered a process of redefinition of both their self-perception and the perception of Europe as a common project. The article offers a case study of how the Polish Members of the European Parliament discursively (re)construct national and European identities and how these constructions relate to each other. The analysis reveals three main visions of the European identity that are voiced by the Polish representation and corresponding visions of national identity. By focusing on the supranational level of the European Parliament and contextualising the analysed constructions with references to national debates, the study is able to nuance the existing theoretical accounts of European and national identities.
The Parental Care Motivational System and Why It Matters (for Everyone)
Authors: Schaller Mark
Published: September 2018

Although it is easy to assume that the psychology of parental care pertains only to parents and their children, this is not so. An emerging body of research on the parental care motivational system reveals implications for everyone. All normally developing human beings are characterized by evolved psychological mechanisms that regulate parental caregiving. These mechanisms are responsive to superficial cues and so (among nonparents as well as parents) can be triggered by the perception of young children or other childlike things. Once activated, these mechanisms precipitate protective and nurturant responses. These responses manifest in many different ways, with implications for a wide range of psychological phenomena (many of which might appear, superficially, to be unrelated to caregiving)—including risk-averse attitudes, aggression, intergroup prejudice, moral judgment, impression formation, and mate preferences. This article provides an illustrative overview of empirical research documenting these implications and identifies new directions for future research on the motivational psychology of parental care.
Microstructural Effects on Damage Behaviour in Particle Reinforced Composites
Authors: Kwon Y. W. , Liu C. T.
Published: September 2018

This paper discusses the effects of non-uniform, random particle distribution on damage initiation and growth, leading to short cracks and breakage of particle reinforced composite specimens. A multi-scale technique was employed to model and simulate damage. Damage was described at the constituent material level (i.e. micro-level) and the results were compared qualitatively and quantitatively with experimental observation. Both results agreed well. Non-uniform, random particle distribution yielded sporadic crack initiation and growth within a uniform tensile specimen. No local crack propagated beyond a certain size. Breakage of the specimens was not caused by the continuous growth of a single critical crack. Instead, coalescence of neighbouring sporadic short cracks resulted in breakage of the specimens. Computer simulation indicated that random particle distribution affected the strength of the composite significantly, but as expected, not its effective stiffness. However, if there was a pre-existing crack in the specimen before loading, the effect of the random particle distribution on the initial crack and the strength of the composite was almost negligible.
Effect of a Two Step Fiber Treatment on the Flexural Mechanical Properties of Sisal-polyester Composites
Authors: Calado V. , Barreto D. W. , d'Almeida J.R.M.
Published: September 2018

Sisal fibers were chemically treated with a two-step treatment (first sodium sulfide aqueous solution and then acetic anhydride/acetic acid mixture) to promote better adhesion to a polyester resin matrix. The flexural behaviour of the composites was analyzed as a function of the time of immersion in distilled water, and there was an improvement for short times of immersion. The long term behaviour of the treated composites was, however, no better than that of the untreated ones. This could be because of the controlling role of plasticization of both the fibers and the resin matrix for the longer times of immersion.
Orientation Effect in Poly (Butylene Succinate) Fibers
Authors: Nakayama K. , Masuda T. , Cao A. , Vega-Baudrit J. , Pereira R.
Published: September 2018

Fibers of poly (butylene succinate) (PBS) were prepared using a single screw extruder at various take-up speeds. Changes in fiber structure, morphology and physical properties were investigated using sonic velocity measurements and X-ray diffraction. High take up speeds enhanced some of the properties of PBS fibers as a consequence of changes in molecular orientation and crystallinity. Spherulites of PBS were also obtained at 90°C.
A Novel Coupling Agent Technology
Authors: Scofield John D
Published: September 2018

The results from the development of a novel coupling agent technology, which should very soon be launched commercially, will be described. The presentation will particularly focus on the performance of the technology in ATH filled EVA systems, and its benefits over existing coupling agent technologies. In particular a rheological profile, giving the potential for lower energy consumption and/or higher processing speeds, can be demonstrated without any significant diminution in the material properties that would be obtained using conventional coupling agents. Other properties related to the fire resistance and electrical stability will be reviewed, and the processing conditions and formulation modifications required to optimise this performance will also be discussed. Other applications for this coupling technology, including calcium carbonate filled EVA systems and hopefully calcium carbonate filled EPDM rubbers and/or PP homopolymer, will be covered in less detail, but should give some indication of the potential scope of the technology.
Excellent Flow- and Conveyance- Behaviour, Low Dust Emission and Outstanding Properties of Halogen Free Flame Retardant Compounds Realized by a New Generation of Aluminium-Tri-Hydrate
Authors: Sauerwein Reiner
Published: September 2018

“A new non-post treated fine precipitated aluminium-tri-hydrate quality has been developed, offering the basis for the next generation of halogen free flame retardant compounds. The paper outlines the excellent powder handling properties and the outstanding performance of highly filled polymers”

Halogen free flame retardant plastics for cable insulation and sheathing, known as LSFOH (low smoke, free of halogen) compounds became large volume products since the market introduction of fine precipitated aluminium-tri-hydrates (ATH) qualities in the beginning of the 80's. While former ATH improvements focused on product purity and electrical properties, recent developments responded to the growing importance of continuous compounding techniques. The focus on compound output and processing behaviour of fillers was answered by ATH qualities having higher bulk density and better flow properties. These improvements have been achieved by physical and chemical post treatments of the precipitated products. While giving the expected benefits in powder handling, detrimental effects have been observed for mechanical and especially for electrical compound properties.

A new generation of non-post treated fine precipitated ATH has now been developed, offering excellent powder processing, but also outstanding compound properties. The paper outlines filler processing behaviour, presenting results of flow-, conveyance-, metering and dust-behaviour investigations. Special attention is given to compound user's benefits. Low melt viscosities and high extrusion speed in the production of LSFOH cables are identified as core properties of compounds filled with this new ATH quality.
Degradation of Poly(vinyl Chloride) with Different Additives, Studied by Micro Raman Spectroscopy
Authors: Gupper Andreas , Wilhelm Peter , Schiller Michael
Published: September 2018

Raman spectroscopy was employed for studies of the thermal degradation of poly(vinyl chloride). Intensity enhancement of vibrations belonging to conjugated double bond sequences in the corresponding spectra allowed the detection of degradation at the very first stage. In this initial period, the kinetics of degradation showed a linear increase in conjugated sequences. Furthermore, the influence of additives on the resistance to thermal stress was investigated by the same method. Plots showing the development of conjugated sequences in the presence of calcium stearate, zinc stearate, and zinc chloride are presented. They are compared with the results for unstabilised poly(vinyl chloride). A clearly positive development in thermal behaviour could be observed upon stabilisation, and predicted reaction mechanisms for single components were confirmed. The goals of this work were: (i) to use Raman spectroscopy for fundamental investigations into the working principles of stabilisers; and (ii) to contribute towards more effective formulations for poly(vinyl chloride) stabilisation, with low ecological impact.
Blown Films from Linear Low Density Polyethylene Incorporating Biodegradable Additive
Authors: Kale Vivek , Jani Kalpesh , Awate Satish , Rangaprasad R , Vasudeo Yatish
Published: September 2018

Environmental concerns are now driving additive suppliers and polymer resin manufacturers to step up efforts to create innovative materials for the future. In the present work, a “biodegradable” additive/promoter was incorporated into a butene-based linear low density polyethylene (LLDPE) at different levels. The properties of the blown films derived therefrom were investigated.

In the first step the “degradation additive/promoter” was converted into a 50% masterbatch in LLDPE. In the second step, this concentrate was let down at 5, 10, 15 and 20% level in a butene-based film grade LLDPE. The properties of the films were characterized. In the third step, the films were subjected to “real-time” degradation tests; using natural soil and under vermicompost conditions. Films subjected to degradation under vermicompost conditions have shown encouraging results. After 3 months, the films containing 15 and 20% additive were found to have disintegrated to a practically unusable form.
Milled Carbon Microfiber-reinforced Poly(phenylenesulfide) Coatings for Abating Corrosion of Carbon Steel
Authors: Sugama Toshifumi , Gawlik Keith
Published: September 2018

Effectiveness of milled carbon microfibers, 7.5 μm in diameter and 100-200 μm long, in increasing the thermal conductivity, tensile strength, and elongation of fiber-reinforced poly(phenylenesulfide) (PPS) composite coatings was investigated. Thermal conductivity depended on the fiber content of the composites; the maximum content (5 wt% fiber) was responsible for a 2.6-fold enhancement over that of non-reinforced ones. However, the most effective amount of fiber in improving the tensile strength and elongation of the composition coating films was 3 wt%, reflecting 5.2 times and 2.6 times improvements, respectively, compared with those of the non-reinforced ones. The composite coatings adequately protected the underlying carbon steel against corrosion in 250°C CO2-laden brine. The reason for their great hydrothermal stability was the conformational changes in the molecular structure of PPS, from sulfide bridging to sulfone bridging, which increased the thermal stability of the matrix.
Poly(∊-Caprolactone) Composites Reinforced with Short Abaca Fibres
Authors: Shibata Mitsuhiro , Yosomiya Ryutoku , Ohta Noritaka , Sakamoto Atsushi , Takeishi Hiroyuku
Published: September 2018

The tensile properties of poly( ∊-caprolactone) (PCL) composites reinforced with short abaca fibres (length ca. 5 mm) prepared by melt mixing and subsequent injection molding were investigated and compared with PCL composites reinforced with glass fibres (GF). The influence of fibre content and surface esterification of the natural fibre on the tensile properties was evaluated. The tensile strength and moduli of all the PCL/abaca composites increased with increasing fibre content. All the PCL/abaca composites had a higher tensile strength than the PCL/GF composites when the fibre weight fraction was the same. The tensile strength of the PCL/abaca composites was improved by surface esterification of the abaca with acetic anhydride or butyric anhydride in the presence of pyridine, because of the increase in the interfacial adhesiveness between the matrix polyester and the esterificated fibre, as is obvious from the SEM photographs.
Influence of Silane Modification of Kaolins on Physico-Mechanical and Structural Properties of Filled PVC Composites
Authors: Domka Ludwik , Foltynowicz Zenon , Jurga Stefan , Kozak Maciej
Published: September 2018

The paper presents the results of a study of the potential of modified kaolin as a filler for PVC. Kaolin from Maria III deposits in Poland was used. Aminosilanes and mercaptosilanes were used to modify the surface. Basic physicochemical parameters, such as the absorption capacity of the plasticiser, the heat of immersion in hydrophobic and hydrophilic solvents, and the morphology of particles of the modified filler were characterised. The modified kaolins clearly improved the physico-mechanical properties of PVC, in particular, they increased the elongation of PVC, when used at 10% and 15% w/w levels in the composite. Some studies of the microstructure of the filled composites were also performed using small angle X-ray scattering (SAXS) and scanning electron microscopy (SEM) techniques.
Electrical Transport Properties of Doped Poly (p-phenylene)
Authors: Campos M.
Published: September 2018

An experimental study of the temperature dependent dc electrical conductivity of doped poly (p-phenylene) in the range of 50-300 K has been presented. The results have been analyzed in the framework of some hopping models. We have observed that hopping models are not consistent with the temperature dependence of the conductivity data over the entire temperature range of measurement. We find that the logarithmic conductivity is proportional to Tβ, where the exponent β is independent of temperature. It is shown that the most probable transport process in this material for the entire range of temperature is due to multiphonon-assisted hopping of the charge carriers that interact weakly with phonons. The parameters obtained from the fits of the experimental data to this model appear reasonable.
Intermediate Velocity Impact Response of Carbon/Epoxy Composites with Polycarbonate Facing
Authors: Vaidya U.K. , Ulven C.A. , Hosur M.V. , Alexander J. , Liudahl L.
Published: September 2018

Woven fabric composites are increasingly being used in composite structures for applications in the aircraft, marine, and automotive industries. With emerging low-cost processing techniques for composite materials, the role of fabric architectures in sustaining low, intermediate, and high velocity impact loads is a subject of interest. An example of a low-cost process is the out-of-autoclave, vacuum assisted resin transfer molding (VARTM) technique. The present study evaluates the intermediate velocity impact response of two commonly used structural carbon fabric laminates produced from plain and 2/2 twill woven fabrics, processed using VARTM. A series of impact tests have been performed on the all plain, all twill and hybrid plain-twill weave carbon/epoxy laminates. All laminates studied were covered with a polycarbonate facing in order to enhance the impact resistance of the carbon/epoxy laminates. The perforation mechanism, ballistic limit, and damage evolution of each laminate has been studied. The results from the experiments are reported.
Rheological Behaviour of PP/PET and Modified PP/PET Blends. I. Steady State Flow Properties
Authors: Zdrazilova Natalie , Hausnerova Berenika , Kitano Takeshi , Saha Petr
Published: September 2018

Both polypropylene (PP) and polyethylene terephthalate (PET) constitute a significant portion of post-consumer waste. To improve the recycling of immiscible PP/PET blends, a compatibiliser should be utilised. The steady shear flow properties of unmodified and modified PP/PET blends having up to 50 wt.% PET were investigated and compared in this study. Three types of PPs with different flow properties were used to ascertain the influence of the matrix on the blend's rheology. The effect of modification on the rheological properties was evaluated in two ways - firstly, the addition of 1 wt.% of maleic anhydride (MA), and secondly, the use of already modified polypropylene. According to the morphological observations, an improvement in compatibility was found in both cases.

The shear viscosity and the first normal stress difference were measured using a rotational cone and plate rheometer at 265°C (when both PET and PP are molten), and 245°C (when only PP has melted). Completely different behaviour was observed under these two temperature conditions. At 265°C, the shear viscosity decreases with PET content in the blend, while at 245°C it increases, thus recalling the behaviour of particle-filled systems. The addition of maleic anhydride affects the shear viscosity in various ways; a decrease, an increase, and some almost unchanged values were obtained. Concerning the first normal stress difference, an even more complex situation occurs, and the effect of modification by MA is also ambiguous. Furthermore, the deviations from the log-additivity rule were evaluated in terms of the shear viscosity and the first normal stress difference. From the results, it can be supposed that PP-X/PET samples were compatibilised successfully, and strong interphase interactions could be expected. Finally, the yield values of shear stress determined at 245°C showed a generally increasing tendency with increasing PET content.
Self-sensing of Damage and Strain in Carbon Fiber Polymer-Matrix Structural Composites by Electrical Resistance Measurement
Authors: Chung D.D.L. , Wang Shoukai
Published: September 2018

The self-sensing of damage and strain in carbon fiber polymer-matrix structural composites has been attained by DC electrical resistance measurement. This paper reviews the self-sensing behavior, in addition to addressing the electrical contact configurations and providing a model for relating the resistance to the damage.
Dual Cure Phenol - Epoxy Resins: Characterisation and Properties
Authors: Devi K. Ambika , Nair C.P. Reghunadhan , Ninan K.N.
Published: September 2018

Reactive blends of 2, 2′- diallyl bisphenol A (DABA) and a novolac epoxy resin (EPN) were investigated for their cure behaviour, and their rheological, physical, mechanical and thermal properties. Cure characterisation was by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The system underwent dual curing through a sequential phenol-epoxy reaction and allyl polymerisation. The former reaction was catalysed by triphenyl phosphine (TPP). Whereas the phenol-epoxy reaction was completed, the allyl polymerization was limited to 40% by the regulation of cure conditions. Increase of epoxy concentration in DABA-EPN blends led to an improvement in the tensile strength and flexural strength of the neat castings. The flexural strength and interlaminar shear strength of the glass laminate showed an improvement with an increase in EPN concentration. Although the crosslink density of the neat casting was enhanced by epoxy-concentration, this did not result in any significant variations in the glass transition temperature (Tg) of the cured matrix. The Tg was in the range 78-82°C. Complete polymerization of all allyl groups resulted in an increase in the Tg and thermal stability while the mechanical properties of the neat system remained practically unaltered. The dual curing of the matrix system resulted in considerable improvement in the flexural properties of their glass composites.
The Properties of GF-Reinforced Thermoplastics in Beam Structure
Authors: Nomura M. , Makita J. , Hamada H.
Published: September 2018

Research has been carried out on the use of glass fibers (hereafter referred to as “GF”) to form a beam structure of GF reinforced thermoplastic composites. GF is generally supplied in lengths 0.2 to 0.6 mm and dispersed in a discontinuous form in a matrix resin in conventional GF reinforced thermoplastic composites. We have successfully developed a method to form a beam structure in which the GF are apparently joined in the matrix resin by utilizing the fact that polymers with a high affinity for GF migrate to the interface of the GF. That is, by adding a small quantity of resin having a higher heat resistance than the matrix resin and having an excellent affinity for GF, we have been successful in joining the fibers by selectively migrating this small quantity of resin to the interface with the GF. This beam structure material was found to have a heat distortion temperature (HDT) significantly higher than that of conventional GF reinforced thermoplastic composites. By applying this concept to glass fiber reinforced polystyrene (GFPS), the HDT of GFPS improved from 100°C - 110°C to 200°C - 250°C.
Melt Viscoelasticity of Polyamide 6/Organoclay Nanocomposites
Authors: Karaman V.M. , Shumsky V.F. , Privalko E.G. , Privalko V.P. , Lehmann B. , Friedrich K.
Published: September 2018

Commercial nanocomposites of polyamide 6, prepared by melt compounding with organoclay hybrids, were characterized by complex viscosities and relaxation time spectra derived from storage and loss shear moduli measured in the melt state at 230°C in the frequency window spanning about three decades.

The results were rationalized in terms of the following model considerations. The decrease of ~25% (compared to the pristine sample) in Newtonian viscosity at the lowest clay loading (2.5%) suggested a lower equilibrium elasticity modulus of an entangled melt, as if the small amounts of organoclay nanoparticles acted as specific “diluents” for the initial entanglement network. However, at increasing clay contents this effect was apparently taken over by the ever growing importance of strong interactions at the nanoparticle/melt interface, leading to the formation of a fairly thick boundary interphase (BI) around the nanoparticles and, eventually, ending up in the build-up of an “infinite cluster” of clay nanoparticles coated with BI at the highest (albeit still unusually low) clay loading (7.5%).
Photophysics and Applications in Plastic Solar Cells of Conjugated Polymer/Fullerene Composites
Authors: Lin Hongzhen , Huang Hongmin , He Qingguo , Bai Fenglian
Published: September 2018

The photovoltaic applications of conjugated polymer/fullerene composites have attracted much attention from the scientific community. The photoinduced electron transfer and other related photophysical processes occurred in the composites are the central issues. Several kinds of conjugated polymers have been synthesized in our laboratory. Studies of their composites with fullerene are reviewed. We observed strong fluorescence quenching of these conjugated polymers on mixing them with C60 in dilute solution. Anion radical species of C60 were observed in ESR measurements as a result of photoinduced charge separation. The quenching constants vary with different conjugated polymers and thus provide a quantum measurement for the interaction between the donor and acceptor. Solar cells have been fabricated from these conjugated polymer/fullerene composites. Energy conversion efficiency up to 1.1% has been achieved.
Intumescent PP Blends
Authors: Almeras X. , Le Bras M. , Bourbigot S. , Hornsby P. , Marosi G. , Anna P. , Poutch F.
Published: September 2018

One way to improve the fire performance of polymers is by the development of intumescent systems.

The addition of ammonium polyphosphate/polyamide-6 is known to provide flame retardancy in many polymers via an intumescent process. The development of appropriate formulations is limited by their mechanical properties. This study shows that polypropylene based intumescent blends are efficient fire retardant systems and that acceptable mechanical properties can be obtained. It is also shown that adding talc improves the mechanical properties of intumescent polypropylene formulations without decreasing their fire retardancy.
Identifying Delamination in Cross-ply and Quasi-isotropic Beams of CFRP by a Standardized Electrical Resistance Method
Authors: Todoroki Akira , Tanaka Yuuki , Shimamura Yoshinobu
Published: September 2018

An electrical resistance change method is widely accepted for the identification of damage in electrically conductive composites. To identify the delamination location more precisely, a new electrical resistance change method involving the standardization of measured electrical resistance changes has been proposed. In the present paper, the new method was applied to cross-ply and quasi-isotropic laminated beams, and the effectiveness of the method was confirmed experimentally. Comparing the results for two different beams, the applicability of the method was confirmed. Moreover, the effect of the stacking sequence was investigated experimentally. Although the standardized electrical resistance changes of the two stacking sequences resembled each other when the delamination location and length were similar, response surfaces to estimate delamination location must be made individually to obtain reliable results.
Synthesis of Organically-Modified Silica Particles for Use as Nanofillers in Polymer Systems
Authors: Arkhireeva Anna , Hay John N.
Published: September 2018

The well-established sol-gel process permits the preparation of a wide range of organic-inorganic hybrid materials directly from molecular precursors under mild conditions. Over the past few years, the sol-gel route has become of tremendous interest because of the remarkable opportunities it offers to produce hybrid nanocomposite particles with a number of potential uses, such as protection and modification of plastics and glasses. In this work, two approaches are described for the preparation of hybrid particles. A modified Stöber method is used to prepare a range of organically-modified silica nanoparticles with diameters in the range of 50-200 nm. The synthesis of organically-modified silica particles has also been carried out using a non-hydrolytic sol-gel route, which has been overlooked for the preparation of hybrid nanoparticles until very recently. The hydrolytic and non-hydrolytic routes have produced hybrids with different structures and morphologies. The organically-modified silica particles synthesised using these sol-gel methods have potential uses as nanofillers in polymer systems.
Novel Functionalised Ethylene Acrylate Copolymers as Polymer Modifiers
Authors: Hausmann Karlheinz , Chou Richard T. , Lee Coreen Y.
Published: September 2018

A novel reactive functionalised polymer modifier system based on ethylene acrylate copolymers produced by a tubular reactor polymerisation process is discussed. The tubular copolymers are unique due to the heterogeneous distribution of acrylate comonomer in the polymer chain making them more compatible with a variety of polymer systems. Because of this feature they can be used as modifiers and universal masterbatch carrier resins for a variety of polymer systems in a more appropriate way than their autoclave based homologues. The new reactive modifiers have excellent compatibility with both polar and non-polar polymers. The incorporation of a reactive functional group, such as maleic anhydride, is used to provide optimal morphology for polymer modification. Impact modification of polyamides using the new acrylate modifier is discussed. Besidessuperior impact properties, the functionalised ethylene acrylate modifier provides improved gloss in moulded parts and flow in polyamide blends compared to conventional reactive modifiers. Another feature of the finished compounds is their high elongation at break. Furthermore, the morphology of the new modifier in PA is discussed. Apart from the modification of polyamides, other applications such as coupling of mineral fillers to polymer matrices is conceivable.
Studies on the Mechanism of Thermal Decomposition of Unsaturated Polyester Resins with Reduced Flammability
Authors: Kicko-Walczak Ewa
Published: September 2018

The thermal decomposition of halogenated unsaturated polyester resins (UPRs), flame retarded by zinc hydroxystannate and cross-linked with styrene, has been investigated by thermogravimetry (TG) in both dynamic and isothermal mode, and by TG coupled on-line with Fourier transform infra red spectroscopy (TG-FTIR) or mass spectroscopy (TG-MS). The data from TG analysis show that degradation proceeds in two steps for unmodified as well as modified UPR, but the char residue at 500°C was considerably higher for flame-retarded resins. Analysis of the volatile decomposition products by FT-IR and MS spectrocopy revealed that during controlled heating, the emission of phthalic anhydride takes place at ca. 330°C, followed by styrene at ca. 380°C., and a complex mixture of other aromatic compounds are evolved. Further studies by TG-FTIR revealed that evolution of CO2 is considerably lowered by zinc hydroxystannate, andat a later stage of decomposition the evolution of H2O and HBr (traces) can be identified. On the basis of the results obtained a mechanism of decomposition was proposed that takes into account the reaction of tin compounds with the products of ester linkage rupture processes.
New Formulations for Syndiotactic Polystyrene
Authors: Kowalska Ewa , Skupinski Wincenty , Wielgosz Zbigniew , Nicinski Karol , Pasynkiewicz Stanislaw
Published: September 2018

The formation of syndiotactic polystyrene in the presence of catalysts was investigated. The yield of syndiotactic polystyrene obtained in a 240 dcm3 pilot plant reactor was 7 - 15 kg/charge. The weight-average molecular weight was about 200 000 g/mol and the syndiotacticity was about 96%.

Composites based on the syndiotactic polystyrene have also been obtained. The polymer was granulated with the stabiliser (Irganox 1076) and modifiers in a twin-screw extruder with double degassing. It was then reinforced by glass fibre or talc. Syndiotactic polystyrene was also modified with polyoxyphenylene and linear polyethylene. The structure and physical and mechanical properties of the composites were investigated.
Hydrothermal Ageing of GF/PP Composites: When Glass/Polymer Adhesion Favours Water Entrapment
Authors: Larivière D. , Krawczak P. , Tibéri C. , Lucas P.
Published: September 2018

This study aims to assess the effects of ageing in boiling water on the transverse tensile mechanical properties of unidirectional commingled GF/PP composites, as well as the influence of the fibre/matrix adhesion on the water absorption and desorption mechanisms. For this purpose, different interfacial qualities were obtained by a modification of the fibre reinforcement sizing (polypropylene specific sizing, or no sizing), and of the matrix (with or without coupling agent). A very good retention of the mechanical properties was observed for those composites which had been treated so as to improve the fibre/matrix adhesion. It is also shown that the better the adhesion, the longer the water remained inside the composite material. This induced effect appears to be the counterpart of the protecting role against moisture of a strong interface. The interfacial interactions act as barriers both during absorption and during desorption. This leads to water molecule entrapment. Hence, the persistence of water trapped at the interfaces in the case of sized glass fibres composites leads us to recommend investigations on the long term effects on longitudinal tension properties, since the effects of zero-stress ageing are known to reduce fibre strength.