bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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.
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.
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.
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.
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.
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%).
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.
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.
Silver Ion Release from Polymethyl Methacrylate Silver Nanocomposites
Authors: Damm Cornelia 
Published: September 2018

Polymethyl methacrylate (PMMA) silver nanocomposites were prepared by the thermal reduction of silver(I) trifluoroacetate. Transmission electron microscopic investigations reveal that the silver nanoparticles were spherical and their particle sizes were between 5 nm and 50 nm. The particles were distributed randomly in the PMMA matrix. Immersion of the nanocomposites in water led to a release of silver ions. The silver ion release from the PMMA silver nanocomposites was measured by anodic stripping voltammetry. When a nanocomposite sample having a surface area of 36.8 cm2 and a silver content of 0.12 wt% was immersed in water, the silver ion concentration in the surrounding water was about 0.05 mg/l after two days. This is sufficient to kill bacteria. Using conventional silver powder as a filler, a silver content 30 times higher is necessary to achieve the same silver ion concentration in the surrounding water under the same conditions. The silver ion concentration in the water increased with increasing nanosilver content of the composites. The composites incorporating conventional silver powder are not transparent. In contrast, PMMA silver nanocomposites containing less than 0.25 wt% silver show a translucency sufficient for use in packaging materials.
EMI Shielding Effectiveness of Copper/Epoxy Composites
Authors: Wetherhold Robert C. , McManaman Joseph M. 
Published: September 2018

Samples of shaped and treated copper (Cu) fibre/brittle matrix composites have been fabricated with a variety of fibre shapes, treatments, diameters, and powder inclusions and tested for shielding effectiveness (SE) using the ASTM standard D4935-99 method over the frequency range 200 to 1500 MHz. A small amount of nickel (Ni) powder was included in some specimens to evaluate the effect of magnetic permeability on SE. Most tests were conducted at constant (15 vol%, “v%”) fibre volume fraction. Results show that a smaller fibre diameter results in significant SE improvements. SE was also substantially improved by relatively minor fibre shaping (which changes along the fibre length) or by fine-scale roughening via chemical treatment. Addition of small amounts of Cu powder leads to major improvements in SE. Most of the improvements are presumably due to the establishment of conductive networks, although fibre shaping or treatment allows greater scattering and thus more internal reflections with attendant absorption. The smaller diameter fibres consistently gave better SE. When a continuous fibre mesh was used, high SE resulted, showing the dominance of fibre connectivity for such materials; the surface condition of the mesh is relatively unimportant. The improvements in SE can be achieved with essentially identical mechanical properties, leading to an effective multifunctional material, although most of the SE values achieved so far are modest. Ni powder results in overall improvement in SE as well as a cyclic dependence of SE on frequency, which indicates phase interference at a scale of particle size not previously seen.
Thermal Stability and Flame Retardancy of Polypropylene with Phosphorus, Nitrogen and Silicon-Containing Compounds
Authors: Li Qiang , Jiang Pingkai , Su Zhanpai , Wei Ping 
Published: September 2018

Flame retardants containing phosphorus, nitrogen and silicone elements have been synthesized. The thermal stabilities of polypropylene (PP), PSiN and PP/PSiN have been studied by thermogravimetric (TG) analysis in nitrogen, air and oxygen atmospheres. The initial decomposition temperature (IDT), maximum-rate degradation temperature (Tmax), integral procedure decomposition temperature (IPDT) and char yield at 800 °C in various atmospheres have been investigated. Although the IDT of PP was reduced by the introduction of PSiN, the Tmax, IPDT and char yield were all increased. The flame retardancy of PP/PSiN composites were evaluated by measuring their Limiting Oxygen Index (LOI) values. Their thermal stabilities agreed with the results of the flame retardancy tests: the PP/PSiN-A exhibited good flame retardancy with LOI of 26.0 and its char yields at 800 °C were 27 wt.% (in nitrogen), 12 wt.% (air) and 12 wt.% (in oxygen). The activation energies of PP, PSiN and PP/PSiN composites in various atmospheres were calculated using the method of Horowitz-Metzger.
Thermal and Morphological Studies of Acrylonitrile–Butadiene (NBR) Latex Reinforced Jute Nonwoven Fabric Composites
Authors: Kumar M.N. Satheesh , Siddaramaiah  , Jagannath J.H. , Bawa A.S. 
Published: September 2018

A series of composites was fabricated by impregnating jute nonwoven fabric in a bath of acrylonitrile-butadiene (NBR) latex. Thermogravimetric analysis of the jute, NBR and their composites were performed in order to establish the thermal stability and mode of thermal degradation. Thermal degradation of the jute fabric and composites was found to proceed in two steps, unlike NBR. All the composites were stable to 280°C. A degradation kinetic parameter was obtained for each stage of degradation of the jute, NBR and their composites, using Broido, Coats-Redfern and Horowitz-Metzger methods. The activation energy (Ea) of the composites for the thermal degradation process lay in the range 39-129, 35-130 and 20-142 kJ/mol for the Broido, Coats-Redfern and Horowitz-Metzger method respectively. Cryogenically fractured specimens were used to analyse the surface morphology of the jute fabric and composites by scanning electron microscopy.
A Theoretical Model of a Magnetic Polymer
Authors: Maiti Pravat Kumar 
Published: September 2018

We report a theoretical model of a magnetic polymer consisting of benzenoid structures incorporated in a simple linear polyethylene-like polymer chain. The benzenoid structures are double ring annulenes having 12, 16, 20 and 24 outer ring π electrons and the benzene ring inside the main cyclic π system. Either six or three covalent bonds of benzene linked to the outer ring carbon atoms at regular intervals will bring planarity to the annulene systems. Hückel molecular orbital theory of quantum chemistry predicts that a 4n (n = 0, 1, 2,….) π alternating cyclic system has a triplet (2s + 1 = 3) stable ground state molecular orbital, provided the cyclic system is planar. Although cyclobutadiene is planar, it is quasi-stable. The 8, 12, 16, 20 and 24 annulenes are not planar but they are stable. If a benzene ring is introduced into the annulene ring and six or three carbon atoms of benzene are covalently linked to the carbon atoms of the outer ring annulene at regular intervals, the annulene systems might become planar. The presence of a benzene ring inside the annulene ring has little influence on the symmetry, electron distribution, energy level and molecular orbitals of the 4n system and as a result it is expected that these modified annulenes would have quite a stable triplet ground state. These predictions are here confirmed by DFT (density functional theory) geometrical optimisation of one of the systems at the B3LYP/6-31+G*level. Calculation of the nucleus independent chemical shift (NICS) at the centre of the ring produces strongly positive values for the triplet 4n annulene structure. Furthermore, the resulting systems do not undergo cyclo-addition (Diels Alder) reactions either at room temperature or in presence of UV radiation. If these planar star-like annulene molecules are incorporated into the polyethylene chain at regular intervals, the polymer is expected to be magneto- active.
Immobilized β-galactosidase: Preparation and Characterization
Authors: Zhang Ji , Zhang Shengtang , Zeng Jiayu , Wang Yunpu , Wang Yongfeng 
Published: September 2018

A new enzyme support consisting of magnetic composite microspheres was prepared using artemisia seed gum, chitosan and magnetic fluid as a source, and characterized. The microspheres contained reactive aldehyde groups that react with the free amino groups of the enzymes. The β-galactosidase was largely immobilized by covalent binding to the surface of the activated magnetic carriers. The factors controlling the relative activity and the enzymic properties of the immobilized β-galactosidase were compared with those of its soluble counterpart, for which ONPG (o-nitrophenol β-D-galactopyranoside) was chosen as a substrate. The pH and thermal stability of the immobilized β-galactosidase were higher than those of the soluble one. The Michaelis constant, Km, was evaluated both for the immobilized β-galactosidase and for the soluble enzyme. The immobilized type exhibited better environmental adaptability and re-usability than the soluble one.
Thermal Decomposition and Oxidation Ageing Behaviour of Polypropylene/Halloysite Nanotube Nanocomposites
Authors: Du Mingliang , Guo Baochun , Liu Mingxian , Jia Demin 
Published: September 2018

The thermal decomposition and oxidation ageing behaviour of polypropylene (PP) and PP/halloysite nanotube (HNT) nanocomposites were studied. The kinetics of thermal decomposition were calculated by integral models. The thermal oxidation ageing was investigated by Fourier transform infrared spectroscopy (FTIR). The PP nanocomposites showed a higher activation energy of thermal decomposition than neat PP. Their surface treatment and lower HNT loading led to a higher activation energy of decomposition. Their improved thermal stability in nitrogen was attributed to entrapment of decomposition products at initial decomposition stage and to barrier effects. Nanocomposites made by using silane-modified HNT (m-HNT) and also those with lower quantities of (unsilanated) HNT showed improved resistance to thermo-oxidative ageing. The rate of thermo-oxidative ageing was correlated with the number of acidic sites and the volume of entrapped oxygen in the lumen of the HNT and in cavities.
Kinetics of Ageing of Wood-Filled Polypropylene-Based Composites
Authors: Nenkova Sanchi , Dobrilova Cvetomira , Vassileva Stefanka , Natov Milcho , Valcheva Eva 
Published: September 2018

The kinetics of light ageing of wood filled composites made from polypropylene filled with unmodified wood flour and with wood flour modified with maleic anhydride (MA) in amounts of 10, 20 and 30% has been investigated. The investigation shows that the light ageing of wood-filled polypropylene-based composites is an autocatalytic chain process. The decrease of the rate constants with increasing wood content showed that the wood flour had a screening effect on light. It is established that the modification of wood flour with MA have a stabilising effect on the ageing of the composite materials owing to a decrease in the number of active centres capable of undergoing oxidation, and in the number of the carbonyl groups.
Thermal and Mechanical Couplings in Plain and Wood Fibre Reinforced Polypropylene during Tensile and Fracture Tests
Authors: Dupre Jean-Christophe , Lagattu Fabienne 
Published: September 2018

The aim of this work was to show the influence of spruce fibres on polypropylene, by way of an experimental thermo-mechanical approach. These studies were performed by the simultaneous measurement of the strain field and the thermal field. A digital image correlation method was used for the strain measurements. The thermal field was obtained with the help of an infrared camera. The heat equation established in the context of classical thermodynamics of irreversible processes allowed us to evaluate the heat sources. The main difference between the plain resin and the composite material was that the heat sources dissipated by the composite were locally lower. In tensile tests the plain material allowed the creation of a neck zone with very high strain values. In fracture tests, it also generated very high strains localised at the crack tip. For the composite, the results of tensile tests showed that the presence of wood fibres led to a quasi-brittle failure of the specimen. In fracture tests, a better overstress accommodation was observed near the crack tip by distributing the strains in a wider zone.