bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Flexible Pavement Mixtures Using Conventional Tests and Ultrasonic Wave Propagation
Authors: Abd Elhafeez Tharwat , Amer Reda , Saad Ahmed , El Kady Hassan , Madi Mohamed 
Published: January 2014

Abstract
This paper presents the results of experimental investigation of flexible pavement dense-graded bituminous wearing course (BWC) and stone matrix asphalt (SMA) for performance and resistance to permanent deformation. Two mixtures of BWC were prepared using different aggregate gradations of crushed dolomite rocks with natural and crushed sands, and 60/70 grade unmodified bitumen. Two mixtures of SMA were prepared from crushed dolomite aggregates with crushed dust and polymer modified binder. Crumb rubber and reclaimed polyethylene were used as modifiers to improve the viscoelastic behavior and rheological properties of 60/70 grade bitumen. Laboratory prepared specimens evaluated using binder properties tests and mixture performance tests including draindown, loaded wheel, marshall, and indirect tensile strength (ITS), and ultrasonic. The results of conventional tests show that a mixture of BWC with crushed sand and SMA with crumb rubber have the highest stability and ITS, with greater reduction in rut depth than the other mixtures. Ultrasonic results show that a mixture of BWC with crushed sand and SMA with crumb rubber have higher elasticity value and failure stress and lower failure strain than the other mixtures. We conclude that variations occur because of changes of aggregate properties, packing of aggregate through the compaction, binder content, and type of modified binders. Ultrasonic wave propagation tests may also be used to evaluate pavement design and performance, as well as conventional tests.
Finite Element Model of Pavement Response Under Load Considering Cross-Anisotropy in Unbound Layers
Authors: Tarefder R. A. , Ahmed M. U. , Islam M. R. , Rahman M. T. 
Published: January 2014

Abstract
The effects of cross-anisotropy of unbound layer materials on the stress-strain response of a pavement under 18 kip truck load are determined at three temperatures employing a dynamic finite element model (FEM) in ABAQUS. Viscoelastic behavior of asphalt materials are characterized by Prony series coefficients estimated from a laboratory dynamic modulus test. Nonlinear elastic behavior of base material is incorporated in ABAQUS through a User Defined Material (UMAT) subroutine. Sub-base and subgrade materials are modeled as linear elastic material using the falling weight deflectometer (FWD) back-calculated moduli and Poisson's ratio. Cross-anisotropy is introduced in the FEM model by changing the ratio of horizontal to vertical stiffness (n-value) of unbound layers, namely base, sub-base, and subgrade layers of an instrumented pavement. The FEM model is validated using field collected stress-strain responses under FWD loading from the instrumented pavement section at mile post 141 (MP 141) on Interstate 40 (I-40) near Albuquerque, NM. It is observed that the tensile strain, transverse to the traffic direction, at the bottom of the asphalt concrete (AC) layer is significantly influenced by the cross-anisotropy of unbound layers. The vertical strain in the AC layer is barely affected by the cross-anisotropy. However, vertical strains in the unbound layers are significantly affected by cross-anisotropy. Therefore, it can be postulated that fatigue damage that is caused by tensile strain at the bottom of the AC layer, and unbound layer rutting that is caused by vertical strain, should be evaluated for unbound layer cross-anisotropy in the design and evaluation of pavements. Overall, strain responses due to cross-anisotropy are highly sensitive to temperature.
Depth Profiling of Residual Stress for Shot-Peened “U”-Bend Alloy-800 Tubes for the PHWR Steam Generator
Authors: Kalpana Nayak I. , Ramana Rao S. V. , Kapoor K. 
Published: January 2014

AbstractResidual tensile stresses influence the mechanical behavior in terms of fatigue and fracture resistance, stress corrosion behavior, and dimensional stability of critical components of nuclear reactors. Glass-bead shot-peened “U”-bend Alloy-800 tubes are used as steam generators in pressurized heavy water reactors (PHWRs), where stress corrosion cracking is the common cause of its premature failure. Therefore, compressive residual stresses are induced by glass-bead shot peening to overcome the tensile stresses generated more along the bend region. The variation of these compressive residual stresses as a function of depth from the surface has been estimated by successive material removal followed by stress measurement. Optimization of electropolishing parameters for removal of a fixed amount of material is carried out. Stepwise removal of material by electropolishing is proved to be better for stress analysis instead of removal “at-a-time.” Effect of shot-peening pressure is also studied as a function of stress pattern developed along the depth from the surface of the straight tube and bent tube.
Short Creep-Fatigue Crack Growth in an Advanced 9 %Cr Steel
Authors: Yan Wentao , Holdsworth Stuart , Kühn Ingo , Mazza Edoardo 
Published: January 2014

Abstract
While the development of short cracks due to cyclic elastic loading has been relatively widely studied, in particular at room temperature, their consideration for cyclic inelastic loading at high temperatures and lower frequencies is not so common. Short creep-fatigue crack growth rates may be correlated in terms of cyclic strain range, cyclic J-integral or strain energy density factor, with appropriate allowance for associated creep damage accumulation. Candidate approaches are evaluated with reference to test results generated for an advanced 9 %Cr turbine rotor steel. This paper promotes the use of cyclic strain range and strain energy density factor relative to other candidate correlating parameters in relation to the results of a series of 30 min hold time creep-fatigue tests performed using fully instrumented uniaxial specimens with short crack starters. The focus of the testing campaign is an advanced 9 %Cr turbine rotor steel at temperatures of 600 and 625°C.
Adrenal insufficiency in acute oral opiate therapy
Authors: Policola Caterina , Stokes Victoria , Karavitaki Niki , Grossman Ashley 
Published: January 2014

SummaryOpiate drugs such as morphine are in extensive use for pain relief and palliation. It is well established that these drugs can cause changes in endocrine function, but such effects are not always sufficiently appreciated in clinical practice, especially in relation to the hypothalamic–pituitary–adrenal (HPA) axis. Herein, we report on an 18-year-old man who was diagnosed with a slipped left femoral epiphysis following a long history of pain in his leg. On examination, he was thought to look relatively young for his age and therefore the orthopaedic surgeons arranged an endocrine assessment, which showed an undetectable concentration of serum cortisol and a suppressed concentration of testosterone; therefore, he was referred urgently with a diagnosis of hypopituitarism. We elicited a history that he had been treated with opiate analgesics for 3 days at the time of his original blood tests. Full endocrine assessment including a short Synacthen test revealed that he now had normal adrenal and pituitary function. We conclude that his morphine therapy had caused profound suppression of his HPA and pituitary–gonadal axes and suggest that clinicians should be aware of these significant changes in patients on even short-term opiate therapy.Learning pointsTherapy with opiates is the standard therapy for severe acute and chronic pain.Such drugs cause profound changes in endocrine function.Importantly, opiates suppress the HPA axis at a central level.Short-term therapy with morphine could be the cause of biochemical adrenocortical insufficiency.Morphine and related drugs also suppress the pituitary–gonadal axis.After discontinuation of therapy with such drugs, adrenal function improves.
Preparation of PbTiO3 Nanotubes by Electrophoretic Deposition Method and Effect of the Electrophoretic Voltage on the Wall Thickness
Authors: Adarmanabadi E. Rahmati , Nourmohammadi A. , Feiz M. H. , Lanki M. 
Published: January 2014

ABSTRACTIn the current research, we have utilized sol-gel electrophoresis technique to grow PbTiO3 nanotube arrays in porous anodic alumina template channels. By using this method high quality and more condense nanotubes are obtained compared with other usual sol-gel methods. Also, the effect of the anodizing parameters on the diameter of the template pores, and effect of electrophoresis voltage on wall thickness were investigated.
Size Also Matters in Biodegradable Composite Microfiber Reinforced by Chitosan Nanofibers
Authors: Pinho Elisabete D. , Martins Albino , Araújo José V. , Reis Rui L. , Neves Nuno M. 
Published: January 2014

ABSTRACTPioneer works on nanocomposites were focused in carbon nanofibers or nanotubes dispersed in epoxy matrix, a viscous liquid facilitating the compounding stage. The interest in developing new composites aimed for biomedical applications led us to design new nanocomposites based in biodegradable polymers with demonstrated biological performance.We report herein the development of micro-nano composites by extruding poly(butylene succinate) (PBS) microfibers with two different diameters, 200 and 500 µm, reinforced with electrospun chitosan nanofibers. Analysis of the microfibers showed high levels of alignment of the reinforcing phase and excellent distribution of the nanofibers in the composite. Its geometry facilitates the development of orthotropy, maximizing the reinforcement in the axial fiber main axis.The biodegradable microfiber composites show an outstanding improvement of mechanical properties and of the kinetics of biodegradation, with very small fractions (0.05 and 0.1 wt.%) of electrospun chitosan nanofibers reinforcement. The high surface area-to-volume ratio of electrospun nanofibers combined with the increased water uptake capability of chitosan justify the accelerated kinetics of biodegradation of the composite as compared with the unfilled synthetic polymer.
Preliminary Investigation of a Sacrificial Process for Fabrication of Polymer Membranes with Sub-Micron Thickness
Authors: Beardslee Luke A. , Khaladj Dimitrius A. , Bergkvist Magnus 
Published: January 2014

ABSTRACTHere we present a single mask sacrificial molding process that allows ultrathin 2-dimensional membranes to be fabricated using biocompatible polymeric materials. For initial investigations, polycaprolactone (PCL) was chosen as a model material. The process is capable of creating 250-500 nm thin, through-hole PCL membranes with various geometries, pore-sizes and spatial features approaching 2.5 micrometers using contact photolithography. The technique uses a mold created from two layers of lift-off resist (LOR). The upper layer is patterned, while the lower layer acts as a sacrificial release layer for the polymer membrane. For mold fabrication, photoresist on top of the layers of lift-off resist is patterned using conventional photolithography. During development the mask pattern is transferred onto the first LOR layer and the photoresist is removed using acetone, leaving behind a thin mold. The mold is filled with a solution of the desired polymer. Subsequently, both the patterned and lower LOR layers are dissolved by immersion in an alkaline solution. The membrane can be mounted onto support structures pre-release to facilitate handling.
A Novel Injectable Chitosan Sponge Containing Brain Derived Neurotrophic Factor (BDNF) to Enhance Human Oligodendrocyte Progenitor Cells' (OPC) Differentiation
Authors: Mekhail Mina , Cui Qiao-Ling , Almazan Guillermina , Antel Jack , Tabrizian Maryam 
Published: January 2014

ABSTRACTWe developed a rapidly-gelling chitosan sponge crosslinked with Guanosine 5'-Diphosphate (GDP). GDP has not been previously explored as an anionic crosslinker, and it was used in this application since the nucleoside guanosine has been shown to improve remyelination in situ, and thus its presence in the sponge composition was hypothesized to induce Oligodendrocyte Progenitor Cells' (OPC) differentiation. In addition to the chemical composition tailored to target OPCs, the developed chitosan sponge possesses a wide range of desirable physicochemical properties such as: rapid gelation, high porosity with interconnected pores, moduli of elasticity resembling that of soft tissue and cytocompatibility with many cell types. Moreover, protein encapsulation into the sponges was possible with high encapsulation efficiencies (e.g. BMP-7 and NT-3). In this study, BDNF was encapsulated in the chitosan sponges with an encapsulation efficiency greater than 80% and a sustained release over a 16-day period was achieved. We demonstrate here for the first time, the attachment of human fetal OPCs to the sponges and their differentiation after 12 days of culture. Overall, this newly-introduced injectable sponge is a promising therapeutic modality that can be used to enhance remyelination post-spinal cord injuries.
Nanoprobe Diffusion in Poly(Vinyl-alcohol) Gels and Solutions: Effects of pH and Dehydration
Authors: Boukari Hacène , Silva Candida , Nossal Ralph , Horkay Ferenc 
Published: January 2014

ABSTRACTWe report fluorescence correlation spectroscopy (FCS) measurements of the translational diffusion of two fluorescent nanoprobes, rhodamine (R6G) and carboxytetramethylrhodamine (TAMRA), embedded in poly(vinyl alcohol) (PVA) solutions and gels. The diffusion coefficient was measured as a function of the PVA concentration and pH. Furthermore, we designed and built an optical chamber to determine the diffusion coefficient of the nanoprobes within the PVA solutions and gels subjected to controlled dehydration. We find that 1) lowering pH causes an apparent slowing down of the diffusion of the nanoprobes, 2) increase of PVA concentration and crosslink density also induce slowing down of both nanoprobes, and 3) dehydration induces systematic decrease of the diffusion of TAMRA in both solutions and gels. Taken together, these results demonstrate that transient physical interactions between the nanoprobes and the PVA linear polymers have a significant effect upon nanoprobe diffusion.
Selenium Nanoparticles Inhibit Various Bacterial Growth on Paper Towels
Authors: Wang Qi , Webster Thomas J. 
Published: January 2014

ABSTRACTBacterial infections are commonly found on paper towels and other paper products leading to the potential spread of bacteria and consequent health concerns. The objective of this in vitro study was to introduce antibacterial properties to paper towel surfaces by coating them with selenium nanoparticles. Results showed that the selenium nanoparticle coated paper towels inhibited the growth of S. Aureus and P. aeruginosa by 80%∼90% after 72 hours compared with the uncoated paper towels. Thus, the study showed that nano-selenium coated paper towels may lead to an increased eradication of bacteria to more effectively clean a wide-range of clinical environments, thus, improving health.
Plasmonic Structures for Near Infrared Applications
Authors: Floris Francesco , Marabelli Franco , Patrini Maddalena , Fornasari Lucia , Quochi Francesco , Figus Cristiana , Bongiovanni Giovanni , Mura Andrea , Saba Michele , Pellecani Paola , Valsesia Andrea 
Published: January 2014

ABSTRACTWe report on the development of a plasmonic-photonic coupled platform based on a plasmonic periodic nanostructure and a host matrix for active media in the visible-near infrared range, constituted by a thin film of sol-gel glass. Here, we report on preliminary results about two main tasks of the research work. On one side, we have studied and optimized the surface that supports plasmonic resonances with tunable wavelengths. On the other side, we focused on improving the sol-gel techniques to form and deposit thin films appropriate for covering the previous surface as well as to protect it (i.e. for sensing applications), embed suitable fluorophores (for active device applications) while avoiding metal-induced radiative emission quenching. Besides structural and optical characterization of the considered structures and films, finite-difference time-domain numerical simulations have been performed, in order to give a feedback on the structure features and thereby interpret its optical response.
Polymer Spraying for Aerosol Jet Etching of Dielectrics for 156-mm Silicon Wafers
Authors: Rodriguez John , Wang Xi , Subbiah Jegadesan , Jie Cui , Lennon Alison J. 
Published: January 2014

ABSTRACTThe front surface of dielectric passivated silicon wafers were spray coated with polyacrylic acid (PAA) using an ultrasonic coating system. A simple model was proposed to correlate the degree of coverage with the number of spray passes. The sprayed PAA films enabled good etching of the dielectric, using a process referred to as aerosol jet etching (AJE), despite the fact that the PAA thickness was non-uniform over the substrate. The AJE tip-to-substrate distance and diameter of the tip were tuned to balance process throughput and the etched line width. Controlling the level of condensation in the aerosol jet printer (AJP) fluid path was critical for etching 156-mm pseudo square silicon wafers.
In situ high temperature X-ray diffraction study of the kinetics of phase separation in the uranium-plutonium mixed oxide (U0.55Pu0.45)O2-x
Authors: VAUCHY Romain , BELIN Renaud.C. , ROBISSON Anne-Charlotte , HODAJ Fiqiri 
Published: January 2014

ABSTRACTUranium-plutonium mixed oxides incorporating high amounts of plutonium are considered for future nuclear reactors. For plutonium content higher than 20%, a phase separation occurs, depending on the temperature and on the oxygen stoichiometry. This phase separation phenomenon is still not precisely described, especially at high plutonium content. Here, using an original in situ fast X-ray diffraction device dedicated to radioactive materials, we evidenced a phase separation occurring during rapid cooling from 1773 K to room temperature at the rate of 0.05 and 2 K per second for a (U0.55Pu0.45)O2-x compound under a reducing atmosphere. The results show that the cooling rate does not impact the lattice parameters of the obtained phases at room temperature but their fraction. In addition to their obvious fundamental interest, these results are of utmost importance in the prospect of using uranium-plutonium mixed oxides with high plutonium content as nuclear fuels.
Wettability of Electrochemically Nano-textured Metallic Glasses
Authors: Arora Harpreet Singh , Mukherjee Sundeep 
Published: January 2014

ABSTRACTDifferent surface patterns with nanometer length-scales were obtained by electrochemical processing of metallic glasses. The wetting behaviour of these surface patterns was studied using sessile drop technique with distilled water droplet. It is demonstrated that the hydrophilic-hydrophobic nature of the metallic glass surface can be controlled through nano topography. The contact angle was found to increase from 70° for the flat metallic glass surface to 112° for the nano-dendritic structure. Atomic force microscopy was utilized to explain the difference in contact angle in term of the surface roughness for different nano-textures.
Nanoparticles synthesis by electron beam radiolysis
Authors: Călinescu Ioan , Martin Diana , Ighigeanu Daniel , Gavrila Adina , Trifan Adrian , Patrascu Mariana , Munteanu Cornel , Diacon Aurel , Manaila Elena , Craciun Gabriela 
Published: January 2014

Abstract
Electron beam (EB) irradiation is a useful method to generate stable silver nanoparticles without the interference of inherent impurities generated from chemical reactions. Our experiments were carried out using linear electron beam accelerators with two different EB absorbed dose rates: 2 kGy min−1 and 7–8 kGy s−1, and with different absorbed dose levels. The optimum conditions for silver nanoparticles (AgNPs) generation by radiolysis, or by radiolysis combined with chemical reduction, were established. In order to obtain a good yield for AgNPs synthesized by radiolysis, a high dose rate is required, resulting in a rapid production process. At low absorbed dose rates, the utilization of a stabilization agent is advisable. By modifying the experimental conditions, the ratio between the chemical and radiolytic reduction process can be adjusted, thus it is possible to obtain nanoparticles with tailored characteristics, depending on the desired application.
Influence of vegetable oil on the synthesis of bioactive nanocarriers with broad spectrum photoprotection
Authors: Niculae Gabriela , Lacatusu Ioana , Badea Nicoleta , Meghea Aurelia , Stan Raluca 
Published: January 2014

Abstract
Due to their unique features, most nanostructured lipid carriers (NLCs) in association with vegetable oils that exhibit UV filtering properties and bioactivity could be used in many cosmetic formulations. Therefore, in this work, a new application of pomegranate seed oil (PSO) in the cosmetic sector was developed, based on the synthesis of bioactive lipid nanocarriers loaded with various UV filters by the hot high pressure homogenization technique. To get broad spectrum photoprotection, different UVA and UVB filters have been used (Avobenzone — AVO, Octocrylen-OCT, Bemotrizinol — BEMT). The influence of the solid lipids combined with PSO on the particle size, physical stability and entrapment efficiency was investigated using 8 nanocarrier systems. An improved physical stability and an appropriate size were obtained for NLCs prepared with Emulgade, carnauba wax and PSO (e.g. −30.9÷-36.9 mV and 160÷185 nm). NLCs showed an entrapment efficiency above 90% and assured slow release rates of UV filters, especially for BEMT (5%). The developed nanocarriers have been formulated into safe and effective sunscreens containing low amounts of synthetic UV filters coupled with a high percent of natural ingredients. The highest SPF of 34.3 was obtained for a cream comprising of 11% PSO and 3.7% BEMT
Saccharomyces cerevisiae yeast immobilized on marrow stem sunflower and polyacrylamide hydrogels
Authors: Calinescu Ioan , Chipurici Petre , Alexandrescu Elvira , Trifan Adrian 
Published: January 2014

Abstract
Biocatalysts with microorganisms immobilized on solid carriers could provide the solution for development of continuous industrial processes for ethanol obtaining by fermentation of sugars. In this study, modified polyacrylamide hydrogels and marrow stem sunflower are used as supports for Saccharomyces cerevisiae yeast immobilization. The obtained structures are used for fermentation of molasses in batch systems. The free yeast cells are used as reference. The modification of polyacrilamide matrix with (2-hydroxyethyl)methacrylate has a positive effect on structure pore uniformity and fermentation performance. The mechanical properties of the obtained biocatalysts are compared. The novel natural matrix has net superior compression strength.