bluuebunny/crossref_metadata_2025 huggingface dataset:
Systematic investigation of bromine monoxide in volcanic plumes from space by using the GOME-2 instrument
Authors: Hörmann C. , Sihler H. , Bobrowski N. , Beirle S. , Penning de Vries M. , Platt U. , Wagner T.
Published: May 2013

Abstract. During recent years, volcanic emissions turned out to be a natural source of bromine compounds in the atmosphere. While the initial formation process of bromine monoxide (BrO) has been successfully studied in local ground-based measurements at quiescent degassing volcanoes worldwide, literature on the chemical evolution of BrO on large spatial and temporal scales is sparse. The first space-based observation of a volcanic BrO plume following the Kasatochi eruption in 2008 demonstrated the capability of satellite instruments to monitor such events on a global scale. In this study, we systematically examined GOME-2 observations from January 2007 until June 2011 for significantly enhanced BrO slant column densities (SCDs) in the vicinity of volcanic plumes. In total, 772 plumes from at least 37 volcanoes have been found by using sulphur dioxide (SO2) as a tracer for a volcanic plume. All captured SO2 plumes were subsequently analysed for a simultaneous enhancement of BrO and the data were checked for a possible spatial correlation between the two species. Additionally, the mean BrO/SO2 ratios for all volcanic plumes have been calculated by the application of a bivariate linear fit. A total number of 64 volcanic plumes from at least 11 different volcanoes showed clear evidence for BrO of volcanic origin, revealing large differences in the BrO/SO2 ratios (ranging from some 10−5 to several 10−4) and the spatial distribution of both species. A close correlation between SO2 and BrO occurred only for some of the observed eruptions or just in certain parts of the examined plumes. For other cases, only a rough spatial relationship was found. We discuss possible explanations for the occurrence of the different spatial SO2 and BrO distributions in aged volcanic plumes.
A sensitivity study of radiative fluxes at the top of atmosphere to cloud-microphysics and aerosol parameters in the Community Atmosphere Model CAM5
Authors: Zhao C. , Liu X. , Qian Y. , Yoon J. , Hou Z. , Lin G. , McFarlane S. , Wang H. , Yang B. , Ma P.-L. , Yan H. , Bao J.
Published: May 2013

Abstract. In this study, we investigated the sensitivity of net radiative fluxes (FNET) at the top of atmosphere (TOA) to 16 selected uncertain parameters mainly related to the cloud microphysics and aerosol schemes in the Community Atmosphere Model version 5 (CAM5). We adopted a quasi-Monte Carlo (QMC) sampling approach to effectively explore the high dimensional parameter space. The output response variables (e.g., FNET) were simulated using CAM5 for each parameter set, and then evaluated using the generalized linear model analysis. In response to the perturbations of these 16 parameters, the CAM5-simulated global annual mean FNET ranges from −9.8 to 3.5 W m−2 compared to the CAM5-simulated FNET of 1.9 W m−2 with the default parameter values. Variance-based sensitivity analysis was conducted to show the relative contributions of individual parameter perturbation to the global FNET variance. The results indicate that the changes in the global mean FNET are dominated by those of net cloud forcing (CF) within the parameter ranges being investigated. The threshold size parameter related to auto-conversion of cloud ice to snow is identified as one of the most influential parameters for FNET in CAM5 simulations. The strong heterogeneous geographic distribution of FNET variance shows parameters have a clear localized effect over regions where they are acting. However, some parameters also have non-local impacts on FNET variance. Although external factors, such as perturbations of anthropogenic and natural emissions, largely affect FNET variance at the regional scale, their impact is weaker than that of model internal parameters in terms of simulating global mean FNET. The interactions among the 16 selected parameters contribute a relatively small portion to the total FNET variance over most regions of the globe. This study helps us better understand the parameter uncertainties in the CAM5 model, and thus provides information for further calibrating uncertain model parameters with the largest sensitivity.
MATHEMATICAL MODELING OF VULCANIZATION CHARACTERISTICS
Authors: Yeoh O. H.
Published: May 2013

It is often useful to describe vulcanization reaction kinetics in terms of a mathematical model so that curing behavior may be predicted for different heat histories. Commonly used models for describing vulcanization kinetics are reviewed and discussed with emphasis on the mathematical relationships between them. The Deng-Isayev, Sestak-Berggren, and Kamal models are regarded as members of a hierarchy of increasing complexity. Simpler members are preferred for robustness. Tests of their validity against experimental data are recommended to guide the choice of models.
EVALUATION OF SIEVE ANALYSIS METHODS FOR THE DETERMINATION OF FIBER CONTENT IN SAMPLES OF RUBBER POWDER
Authors: Rodríguez-Alloza Ana María , Gallego-Medina Juan , Bermejo-Muñoz José María , Saiz-Rodríguez Leticia
Published: May 2013

The objective of this article is to study the validity of the test methods that are currently used to determine the fiber content in samples of rubber powder made from end-of-life tires: CEN/TS 14 243, ASTM D 5603-01, and XP T 47–758. For this purpose, rubber powder samples contaminated with one weight percent (wt%) of fiber were prepared and submitted to sieve analyses, with the weight of the sample and sieving time as the variable parameters. The materials used were rubber powder without fibers and polyester fibers from recycled waste tires, both generated during the shredding of the tires. It has been observed that the procedure of determining fiber content based on sieving and extraction of fabric balls does not manage to recover more than 41.00% of the fibers contained in the samples. This research demonstrates that even with different sample weights and sieving times, is not possible to recover 100% of the fiber with which the rubber sample was contaminated. This seems to indicate that it is necessary to develop a methodology that differs from the current practice of sieving and extracting fabric balls to correctly determine the fiber content in a sample of rubber powder.
CALCIUM SILICATE (CASIO3) AS ALTERNATIVE IONIC COAGULANT AND SOLID LUBRICANT FOR CERAMIC MOLDS IN NATURAL RUBBER LATEX FILM PREPARATION
Authors: Tangboriboon Nuchnapa , Pakdeeniti Sirikarn , Kunanuruksapong Ruksapong , Sirivat Anuvat
Published: May 2013

Calcium silicate gel (CaSiO3) is a synthesized, ionic coagulant and solid lubricant prepared by the sol-gel process. Calcium silicate is an oxide compound used as an ionic coagulant in coatings on prototypic, standard molds before those molds are dipped into concentrated natural rubber latex in the latex film-production process. The advantages of coating the CaSiO3 gel, made from eggshells, on a ceramic mold surface are low water treatment, less-acid rising step, and a longer life of the standard molds. Synthesized CaSiO3 has good physical properties: a specific surface area of 107 m2/g, a small pore diameter of 14.91 nm, and a fine, average particle size of 20.76 μm, suitable for coating on standard or other ceramic molds. The concentrated latex film products obtained are thin and clear, with a smooth surfaces; they provide ease of mold release and have high tensile strength. The interfacial interaction γSL, between a prototype standard mold and the CaSiO3 gel, as an ionic coagulant is stronger than the γSL between a prototype standard mold and calcium nitrate gel is because of the electrostatic charges of CaSiO3 (Ca2+, Si4+, and O2−) on the mold surface.
MUSSEL-MIMETIC ELASTOMERS OF VARIED FUNCTIONALITY DESIGN FOR ELASTOMERIC COMPOSITES
Authors: Pan Xiao-Dong , Yan Yuan-Yong , Qin Zengquan , Brumbaugh Dennis R. , Sadhukhan Pat
Published: May 2013

Bulk viscoelasticity and tensile behavior are examined for cross-linked compounds made of mussel-mimetic elastomers of varied functionality design. During polymerization, the mussel-mimetic functionalities containing the 3,4-dihydroxyphenyl (or catechol) group can be incorporated at the molecule chain head, along the backbone, and/or at the molecule chain tail. The compounds are either unfilled or filled to the same filler volume fraction with a single filler chosen among carbon black (hydrophobic), precipitated silica (hydrophilic), and titanium oxide (hydrophilic). For polymers bearing multiple mussel-mimetic functional groups, the polymer cold flow resistance becomes significantly enhanced, arising from the strong intermolecular hydrogen bonding interactions. Such strong intermolecular hydrogen-bonding interactions also affect the bulk viscoelasticity and tensile behavior for the cross-linked gum compounds. Because the mussel-mimetic functional groups exhibit obvious affinity to all three types of filler particles, the extent of modification to bulk viscoelasticity and reinforcement for the filled compounds is observed to vary with the distribution of such functionalities along a polymer molecule, the chemical groups immediately next to the catechol group, and the specific type of filler. As expected, microscale filler dispersion is improved from the strong polymer–filler interactions.
MAPPING STORAGE MODULUS AND LOSS MODULUS OF POLYOLEFIN/POLYSTYRENE BLENDS WITH ATOMIC FORCE MICROSCOPY
Authors: Yablon Dalia G. , Proksch Roger , Gannepalli Anil , Tsou Andy H.
Published: May 2013

The storage modulus and loss modulus of blends of polypropylene/polystyrene and polyethylene/polystyrene have been mapped quantitatively with contact resonance atomic force microscopy. Contact resonance spectra were collected in Dual AC Resonance Tracking (DART) mode, in which the phase and amplitude are monitored at two discrete frequencies, resulting in maps of contact resonance frequency and quality factor. These data are then used to compute quantitative storage and loss moduli parameters for the materials being imaged. Computed storage moduli compare favorably with the high-frequency, time–temperature, superposed, low-frequency dynamic mechanical analyzer (DMA) values, whereas the computed loss moduli exhibited greater uncertainty in comparison with the bulk DMA values.
ROLE OF MATERIAL COMPOSITION IN THE CONSTRUCTION OF VISCOELASTIC MASTER CURVES: SILICA-FILLER NETWORK EFFECTS
Authors: Maghami S. , Dierkes W. K. , Tolpekina T. V. , Schultz S. M. , Noordermeer J. W. M.
Published: May 2013

One of the important aspects in the development of new tire compounds is the correlation between the dynamic mechanical properties of the rubber, measured on a laboratory scale, and the actual tire performance. The measuring protocol for dynamic mechanical properties with high precision and good correlation with tire properties is therefore of main concern. To predict wet traction, the viscoelastic behavior of the rubber materials at high frequencies (in the MHz range) need to be known. Viscoelastic master curves derived from time-temperature superposition can be used to describe the properties of the materials over a wide frequency range. The construction of master curves for tread compounds filled with different amounts of silica is discussed. From the vertical shifts as a function of temperature, activation energies are derived that apparently are in the linear response region by fulfilling the Kramers-Kronig relations, and their values correspond to physical phenomena as the underlying principle. Strain sweep viscoelastic measurements, per definition outside the linear region, lead to much higher activation energies. Because the deformation strains employed for these strain sweep measurements are more realistic for wet traction or skidding phenomena, it is concluded that the value of the above measurements in the linear region to predict traction is only limited or a first but still important indication.
COMPREHENSIVE NUMERICAL MODEL FOR THE INTERPRETATION OF CROSS-LINKING WITH PEROXIDES AND SULFUR: CHEMICAL MECHANISMS AND OPTIMAL VULCANIZATION OF REAL ITEMS
Authors: Milani Gabriele , Milani Federico
Published: May 2013

This work presents a comprehensive numerical model to optimize mechanical properties of thick rubber vulcanized items, comprising medium and high voltage electric cables and three-dimensional devices. Several vulcanization systems are considered, including peroxides and accelerated sulfur. For peroxides, both a genetic algorithm (GA) and an alternating tangent (AT) approach are adopted to determine the optimal final mechanical properties (tensile strength) of rubber items. The use of a mixture of peroxides is also considered, demonstrating that balanced mixtures may help in reducing the curing time and/or in increasing the optimal tensile strength in both core and skin of thick devices. For sulfur vulcanization, a mathematical kinetic model is presented to predict the cross-linking density of vulcanized rubber. The model is conceived to fit experimental rheometer data, and it is suitable to have an estimate of cross-linking degree at fixed temperature. The model requires a parametric calibration by means of only three kinetic constants, successively implemented in Finite Element (FE) software, specifically developed to perform thermal analyses on two-dimensional geometries. As an example, an extruded cylindrical thick EPDM item is considered and meshed through four-noded isoparametric plane elements. Several FE simulations are repeated changing both exposition time, tc, and external curing temperature, Tc, to evaluate for each (tc, Tc) couple the corresponding mechanical properties of the item at the end of the thermal treatment.
MODIFICATION OF SKIM RUBBER BLENDED WITH POLY (VINYL ALCOHOL) TO BE APPLIED AS A BIODEGRADABLE PRESSURE-SENSITIVE ADHESIVE: EFFECT OF 2,6-DI-T-BUTYL-4-METHYLPHENOL AND HYDROCARBON RESIN
Authors: Riyajan Sa-Ad , Pheweaw Nataphon
Published: May 2013

Pressure-sensitive adhesives (PSAs), or self-adhesives, are used in many applications, including safety labels for power equipment, automotive interior trim assembly, and sound/vibration–damping films. The objective of this study was to develop a biodegradable skim rubber–based bioadhesive blended with poly (vinyl alcohol) (PVA), which has the advantage of being biodegradable and biocompatible to humans. PSAs were produced from saponified low-protein skim rubber (S-LPSR) alone using a hydrocarbon resin as a tackifier and blends of S-LPSR/PVA containing tackifier, via solution and emulsion, respectively. The influence of 2,6-di-t-butyl-4-methylphenol (BHT) and the hydrocarbon resin content in the adhesive formulation was studied. Various methods were used to evaluate the properties of the adhesives produced including scanning electron microscopy, differential scanning calorimetry, contact angle measurement, dynamic mechanical thermal analysis, and Fourier transform infrared spectroscopy. The optimal concentration of PVA for a good PSA was found to be 20 phr because of its emulsion form. The adhesion properties of a PSA containing 50–60 phr of hydrocarbon resin and 1% BHT displayed excellent tack and peel compared with other samples because there was no chain scission of the skim rubber and good compatibility and interaction between the S-LPSR/PVA blend and the hydrocarbon resin, which maximized the adhesion properties of the adhesive.
ELASTOMER NANOCOMPOSITES BASED ON BR/EPDM/ORGANOCLAY
Authors: Kharazmkia M. , Naderi G. , Ghoreishy M. H. R. , Shokoohi S.
Published: May 2013

Elastomer nanocomposites based on BR, EPDM, and Cloisite 15A were prepared via melt compounding on a laboratory scale two-roll mill. Effect of BR/EPDM composition ratio (0/100, 75/25, 50/50, 25/75, and 100/0) and nanoclay content (3, 5, 7, and 10 w/w) on the microstructure, mechanical, and rheological properties of BR/EPDM/organoclay nanocomposites were studied. Cure characterization results of the prepared elastomer nanocomposites are indicative of the accelerative role of nanoclay in the vulcanization reaction of matrix elastomer chains. The remarkable increase observed in the torque values as well as the increasing trend of gel contents represent the cross-link density increment at the presence of organoclay. Results of x-ray diffraction (XRD) analysis showed an increase in the d-spacing values associated with the silicate layers indicating the intercalation of matrix elastomer chains into the clay galleries. Transmission electron microscopy micrographs of nanocomposite samples depict an intercalated/partially exfoliated microstructure confirming XRD results. According to the measured mechanical pr7operties, incorporation of organo-modified montmorillonite improved the mechanical properties of BR/EPDM compounds. This could be ascribed to the establishment of interactions between silicate layers and polymer matrix that was evidenced by scanning electron microscopy photomicrographs and enhanced rheological properties.
THERMAL PROTECTION OF POLYAMIDE 6/ACRYLONITRILE–BUTADIENE RUBBER THERMOPLASTIC-VULCANIZATES: INFLUENCE OF TYPE AND CONTENT ON BLEND PROPERTIES
Authors: de Oliveira Gomes Ana Catarina , Gomes Oliveira Marcia , Marcio Paranhos Caio , Guenther Soares Bluma
Published: May 2013

Polyamide 6 (PA6)/NBR blends are interesting because of their supposed properties at elevated temperatures. The blend, however, has a critical problem in terms of processing stability, as a result of the thermal degradation of the NBR phase. We evaluate a system of dissimilar addition of antioxidant in each phase (a combination of Irganox®/Irgafos® for the PA phase, and Naugard 445® for the NBR phase) and study the influence of these antioxidants on the properties of the blend. The evaluation was performed through tensile strength, differential scanning calorimetry (DSC), thermogravimetric analysis, and X-ray diffraction analysis. The influence of the antioxidant system on the crystallization process of the PA phase was evaluated through isothermal DSC analysis. Results showed the best combination of antioxidant addition in master batches and during processing.
MODIFIED GUTH–GOLD EQUATION FOR CARBON BLACK–FILLED RUBBERS
Authors: Fukahori Y. , Hon A. A. , Jha V. , Busfield J. J. C.
Published: May 2013

The modulus increase in rubbers filled with solid particles is investigated in detail here using an approach known widely as the Guth–Gold equation. The Guth–Gold equation for the modulus increase at small strains was reexamined using six different species of carbon black (Printex, super abrasion furnace, intermediate SAF, high abrasion furnace, fine thermal, and medium thermal carbon blacks) together with model experiments using steel rods and carbon nanotubes. The Guth–Gold equation is only applicable to such systems where the mutual interaction between particles is very weak and thus they behave independently of each other. In real carbon black–filled rubbers, however, carbon particles or aggregates are connected to each other to form network structures, which can even conduct electricity when the filler volume fraction exceeds the percolation threshold. In the real systems, the modulus increase due to the rigid filler deviates from the Guth–Gold equation even at a small volume fraction of the filler of 0.05–0.1, the deviation being significantly greater at higher volume fractions. The authors propose a modified Guth–Gold equation for carbon black–filled rubbers by adding a third power of the volume fraction of the blacks to the equation, which shows a good agreement with the experimental modulus increase (G/G0) for six species of carbon black–filled rubbers, where G and G0 are the modulus of the filled and unfilled rubbers, respectively; ϕeff is the effective volume fraction; and S is the Brunauer, Emmett, Teller surface area of the blacks. The modified Guth–Gold equation indicates that the specific surface volume ()3 closely relates to the bound rubber surrounding the carbon particles, and therefore this governs the reinforcing structures and the level of the reinforcement in carbon black–filled rubbers.
HEAT BUILD-UP OF RUBBER UNDER CYCLIC LOADINGS: VALIDATION OF AN EFFICIENT DEMARCH TO PREDICT THE TEMPERATURE FIELDS
Authors: Le Saux V. , Marco Y. , Calloch S. , Charrier P. , Taveau D.
Published: May 2013

Rubber-like materials exhibit a hysteretic behavior under cyclic loadings that, combined with a very low thermal conductivity, leads to a temperature rise called heat build-up in the literature. This phenomenon is especially crucial for antivibration parts that require both good fatigue resistance and high damping properties, involving a high dissipation under cyclic loading. Moreover, these parts exhibit complex shapes leading to complex local mechanical fields and therefore to thermal sources and temperature fields difficult to predict. To overcome the difficulties of the classical approach based on thermodynamically based models and to provide acceptable characterization and computation times for industrial needs, a simple phenomenological approach was previously suggested. We aim at validating this approach for several case studies. First, an identification procedure is proposed to identify efficiently the parameters of the thermal and mechanical problems, from a single test on an hourglass-shaped specimen. The validity of the identification step and of the modeling is then challenged by the confrontation of the numerical predictions to the results of an extended experimental database. The influences of the main influent factors are investigated (displacement amplitude, frequency, load ratio, sample volume) for tension and torsion tests on hourglass-shaped samples. The validity of the approach is asserted both on transient and stabilized temperature fields, for a temperature rise lower than 20 °C.
PREPARATION AND PROPERTIES OF STYRENE-BUTADIENE RUBBER/CLAY NANOCOMPOSITES BY USING LIQUID RUBBER/CLAY MASTER BATCHES
Authors: Fang Liang , Wei Ming , Warasitthinon Nuthathai , Shen Jia , Jian Rui , Schmidt Daniel , Barry Carol , Mead Joey
Published: May 2013

Rubber/clay nanocomposites (RCNs) have many applications because of their improved properties. The dispersion of clay in a rubber matrix, which plays an important role in the properties of RCNs, is a challenge. In this article, a solvent-free approach to produce the styrene butadiene rubber (SBR)/clay nanocomposites by using liquid rubber/clay master batches was introduced. The liquid/rubber master batches were first prepared using a high-speed centrifugal mixer and then compounded with neat SBR using conventional rubber compounding equipment. Compared with the composites prepared by melt mixing, this approach resulted in a better dispersion of the clay in the rubber matrix and improvements in tensile strength (4.98 MPa at 10 phr clay loading) and elongation at break (>1000% at 10 phr clay loading). The improved dispersion was confirmed by X-ray diffraction. The effect of clay loading on the tensile properties, dynamic mechanical properties, and the Payne effect was also investigated. The increase in clay loading resulted in a steady increase in the tensile properties up to a loading of 15 phr. The reinforcement in the RCN modulus using clay was compared with five models, including the Guth and Halpin-Tsai equations. This solvent-free approach offers benefits in dispersion of clay for industrial applications of rubber nanocomposites.
HYDROGENATED BUTADIENE-ACRYLONITRILE-BUTYLACRYLATE RUBBER AND ITS PROPERTIES
Authors: Yue Dongmei , Wei Xinpeng , Wang Xunzhang , Wang Weimin , Zhang Liqun
Published: May 2013

Butadiene-acrylonitrile-butylacrylate rubber (BNBR), which is synthesized by copolymerization of butadiene, acrylonitrile, and butyl acrylate, retains excellent properties of oil resistance and heat resistance because of the introduction of -CN, -COOR in the polymer. However, the presence of a lot of carbon-carbon double bonds (-C=C-) could lead to deterioration of material properties such as thermal stability and ozone resistance. To improve the properties of unsaturated elastomers, further chemical modification of diene-based polymers is very critical. Hydrogenation is a useful chemical modification method that can improve the thermal stability of diene-based polymer. BNBR was hydrogenated by homogenous hydrogenation using the Wilkinson catalyst RhCl(PPh3)3 in xylene. The effects of catalyst concentrations, reaction times, and hydrogen pressures on the conversion and product selectivity were discussed. The degree of hydrogenation was measured by proton nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. The thermal stability of hydrogenated and nonhydrogenated copolymers was evaluated by thermogravimetric analysis (TGA). The CCD camera was used to characterize the ozone resistance of hydrogenated copolymer (HBNBR). The results obtained by TGA and the CCD camera show that the maximum saturation level is a critical factor for improvement of thermal stability and the ozone resistance of HBNBR.
Reversal of Pulmonary Hypertension after Diaphragm Pacing in an Adult Patient with Congenital Central Hypoventilation Syndrome
Authors: Morélot-Panzini Capucine , Gonzalez-Bermejo Jesus , Straus Christian , Similowski Thomas
Published: May 2013

Introduction

Patients with the congenital central hypoventilation syndrome (CCHS) suffer from life-threatening hypoventilation when asleep, making them dependent on mechanical ventilation (MV) at night or during naps. State-of-art respiratory management consists of intermittent positive-pressure ventilation via a tracheotomy or mask. In some patients hypoventilation is permanent, in which case ventilatory support must be extended to the waking hours. Diaphragm pacing can prove useful in such situations.

Methods and Results

This report describes the case of a 26-year-old woman with CCHS in whom failure to achieve adequate MV led to life-threatening pulmonary hypertension (PH), with a systolic pulmonary artery pressure (PAP) of 80 mmHg and right ventricular hypertrophy, despite optimization of all possible measures and despite extensive therapeutic education efforts. Diaphragm pacing using laparoscopically implanted intradiaphragmatic phrenic nerve stimulation electrodes corrected alveolar hypoventilation and lastingly reversed PH (systolic PAP below 40 mmHg after 2 months, sustained after 2 years). Diaphragm pacing induced shoulder pain, however, involving the chronic use of analgesics. The pacing had to be stopped for tolerance reasons after two years, leading to PH worsening and the need for diurnal MV.

Conclusions

Diaphragm pacing appears likely effective to restore alveolar ventilation and reverse PH in adult CCHS patients.
Mobile-Bearing Total Knee Arthroplasty: A Full Traumatic Rotation of 180°
Authors: Sudanese Alessandra , Castiello Emanuela , Affatato Saverio
Published: May 2013

From February 2008 to September 2012 we implanted 204 mobile-bearing knee prostheses in 192 patients. All the prostheses were cemented (both femoral and tibial components), and the patella was not replaced. Only one early complication of the implants (1/204 = 0.004%) occurred after a traumatic event as a full 180° rotation of the mobile-bearing polyethylene insert. A 78-year-old woman presented with swelling and severe pain at her right knee. This traumatic event was the only case among our mobile-bearing insert patients.

The failed polyethylene inserts were retrieved and studied using a scanning electron microscope (SEM, ZEISS EVO 50 EP, Cambridge, UK) operating at 20 kV.

Scratching and pitting were found on the UHMWPE insert perpendicular to the machining tracks for the concave surface. SEM micrographs of the insert showed burnishing on the concave surfaces and longitudinal scratches were clearly detectable and well-marked on the analyzed surfaces.

A traumatic, fully rotating, polyethylene insert is rare and our case is the first report describing a traumatic event with a complete 180 degree rotation mobile-bearing in a total knee prosthesis.

In the literature few reports discuss clinical outcomes after total knee arthroplasty in patients with Parkinson's disease and they cite mixed results. However, some authors suggest that posterior-stabilized and cruciate-retaining TKA should work well while others prefer cruciate-retaining, condylar constrained kinetics, or hinged devices. Although we did not implant a posterior-stabilized mobile-bearing total knee prosthesis or a constrained prosthesis, we obtained good clinical and radiological results at the 2-year followup.
Comparative Study between Robust Control of Robotic Manipulators by Static and Dynamic Neural Networks
Authors: Ghrab Nadya , Kallel Hichem
Published: May 2013

A comparative study between static and dynamic neural networks for robotic systems control is considered. So, two approaches of neural robot control were selected, exposed, and compared. One uses a static neural network; the other uses a dynamic neural network. Both compensate the nonlinear modeling and uncertainties of robotic systems. The first approach is direct; it approximates the nonlinearities and uncertainties by a static neural network. The second approach is indirect; it uses a dynamic neural network for the identification of the robot state. The neural network weight tuning algorithms, for the two approaches, are developed based on Lyapunov theory. Simulation results show that the system response, equipped by dynamic neural network controller, has better tracking performance, has faster response time, and is more reliable to face disturbances and robotic uncertainties.
LEAF STRUCTURE OF MANGROVE SPECIES TO UNDERSTAND THE SPECTRAL RESPONSES
Authors: Lucena Ivanilson , Maciel Vanessa Emanuelle de Oliveira , Silva Janaina Barbosa da , Galvíncio Josiclêda Domiciano , Pimentel Rejane Magalhães de Mendonça
Published: May 2013

The preservation of ecosystems such as mangroves plays a key role in mitigating the negative effects arising from climate change, especially for the capture of atmospheric carbon dioxide, the main agent of degradation of the ozone layer. The remote sensing application studies aim to develop that allows the preservation of ecosystems such as mangroves. This study aims to evaluate the anatomical structure of three species in a mangrove established at Pernambuco State as an aid in understanding the spectral responses shown by these species. Mature leaves of Rhizophora mangle, Laguncularia racemosa and Avicennia schaueriana were collected in the estuary of Maracaípe, in the district of Ipojuca-PE, and cross-sections of leaf lamina and epidermis dissociation were performed, following usual procedures in plant anatomy. Individuals of R. mangle showed the highest values of thickening of the cuticle and epidermis. A. schaueriana detached through the highest values for the thickness of palisade and L. racemosa showed the highest values for the thickening of the spongy parenchyma. The species showed different structural characteristics with different action related to the reflectance, absorptance, and transmittance, allowing the use of remote sensing techniques for proper assessment of vegetation conditions for the preservation of the environment.
ANALYSIS OF GEOSTATISTICS THROUGH ROUGHNESS DATA SAMPLING OF SOIL AT DIFFERENT SCALES
Authors: Siqueira Glécio Machado
Published: May 2013

Erosion is dependent on factors such as volume and intensity of rainfall, the infiltration rate of the soil water storage capacity and surface soil water. In this sense, the study of surface roughness of the soil favors the understanding of a number of factors related to the process of soil erosion, favoring thus reducing the damage caused by degradation by soil erosion. On the other hand, you also need to understand how soil surface roughness manifests itself after the incidence of distinct rainfall because the rainfall intensity also plays an important role on the process of soil degradation. The use of geostatistics to the spatial modeling is based in most cases on the assumption of stationarity of data. The objective of this study was to evaluate the spatial distribution of soil roughness in experimental microplots and validate the intrinsic hypothesis of geostatistics. The soil aggregates of 3-5 cm were collected in the city of Lugo (Spain). In the laboratory experimental plots (200 mm x 200 mm, 400 mm x 400 mm, 600 mm and 600 mm x 800 mm x 800 mm) were constructed using metal base mobile 0.86 mx 0.86 m (0.73 m2 ), and the roughness of the ground (dm) measured with rugosimeter laser. Os different size plot for determining the soil surface roughness demonstrated stability in statistical and geostatistical parameters, allowing determination of random roughness index (RR) reliably , regardless of portion size. The validation of the intrinsic hypothesis of geostatistics using data from soil roughness was only possible because the data are homogeneous and represent the same phenomenon in a continuous manner.
Changing Spatial Patterns of Agriculture in the Punjab Province and the Food Sustainability
Authors: Syed Shahid Ali
Published: May 2013

Pakistan is essentially an agricultural country as most of the population is still living in the rural areas and depending on agriculture for their livelihood. Increasing population is putting more and more pressure on the agricultural lands of the country to fulfill the food requirement. Forty four percent of the labor force of the country is alone shared by agriculture sector. Its importance increases as the most of the industries are also dependent on the agricultural products as their raw material. The province of Punjab is the agricultural hub of the country and playing a vital role in supplying the food grain and other agricultural products not only to the population within the province but to all other parts of the country. The districts in the province are producing the major grain crops, which is quite sufficient for showing the level of sustainability for the population within their limits. Only few districts in the Punjab with highly populated urban centers such as Lahore, Rawalpindi and Islamabad are showing somewhat lower shares of agricultural contribution.
Application of Spatially Fractionated Radiation (GRID) to Helical Tomotherapy using a Novel TOMOGRID Template
Authors: Zhang X. , Penagaricano J. , Yan Y. , Sharma S. , Griffin R. J. , Hardee M. , Han E. Y. , Ratanatharathom V.
Published: May 2013

Spatially fractionated radiation therapy (GRID) with megavoltage x-ray beam is typically used to treat large and bulky malignant tumors. Currently most of the GRID treatment is performed by using the linear accelerator with either the multileaf collimator or with the commercially available block. A novel method to perform GRID treatments using Helical Tomotherapy (HT) was developed at the Radiation Oncology Department, College of Medicine, the University of Arkansas for Medical Sciences. In this study, we performed a dosimetric comparison of two techniques of GRID therapy: one on linear accelerator with a commercially available GRID block (LINAC-GRID) as planned on the Pinnacle planning station (P-TPS); and helical tomotherapy-based GRID (HT-GRID) technique using a novel virtual TOMOGRID template planned on Tomotherapy treatment planning station (HT-TPS). Three dosimetric parameters: gross target volume (GTV) dose distribution, GTV target dose inhomogeneity, and doses to regions of interest were compared. The comparison results show that HT-GRID dose distributions are comparable to those of LINAC-GRID for GTV coverage. Doses to the majority of organs-at-risk (OAR) are lower in HT-GRID as compared to LINAC-GRID. The maximum dose to the normal tissue is reduced by 120% for HT-GRID as compared to the LINACGRID. This study indicate that HT-GRID can be used to deliver spatially fractionated dose distributions while allowing 3-D optimization of dose to achieve superior sparing of OARs and confinement of high dose to target.
Adaptive control of an underactuated spherical robot with a dynamic stable equilibrium point using hierarchical sliding mode approach
Authors: Yue Ming , Liu Baoyin
Published: May 2013

Unlike the traditional underactuated mechanical system, the equilibrium point of the inner swing‐up suspension of a spherical robot possesses stable and dynamic characteristics. The stable dynamic equilibrium position of the underactuated suspension must agree well with the uncertain rolling resistance in practice. To overcome this special underactuated problem with dynamic equilibrium, we present an adaptive control scheme to enhance the ground adaptability using hierarchical sliding mode approach. The control method can drive the spherical robot to a desired position, and at the same time, the suspension subsystem holds on their dynamic equilibrium points rapidly. The proposed control approaches are verified to be effective by numerical simulation for a spherical robot to achieve satisfactory control performances, such as ground adaptability, rapid convergence, and disturbance rejection. Copyright © 2013 John Wiley & Sons, Ltd.
Sensory Arrays of Covalently Functionalized Single‐Walled Carbon Nanotubes for Explosive Detection
Authors: Schnorr Jan M. , van der Zwaag Daan , Walish Joseph J. , Weizmann Yossi , Swager Timothy M.
Published: May 2013

Chemiresistive sensor arrays for cyclohexanone and nitromethane are fabricated using single‐walled carbon nanotubes (SWCNTs) that are covalently functionalized with urea, thiourea, and squaramide containing selector units. Based on initial sensing results and 1H NMR binding studies, the most promising selectors are chosen and further optimized. These optimized selectors are attached to SWCNTs and simultaneously tested in a sensor array. The sensors show a very high level of reproducibility between measurements with the same sensor and across different sensors of the same type. Furthermore, the sensors show promising long‐term stability, which renders them suitable for practical applications.
Efficient Delivery of p53 and Cytochrome C by Supramolecular Assembly of a Dendritic Multi‐Domain Delivery System
Authors: Ng David Yuen Wah , Fahrer Jörg , Wu Yuzhou , Eisele Klaus , Kuan Seah Ling , Barth Holger , Weil Tanja
Published: May 2013

Versatile nanocarrier systems facilitating uptake of exogenous proteins are highly alluring in evaluating these proteins for therapeutic applications. The self‐assembly of an efficient nano‐sized protein transporter consisting of three different entities is presented: A streptavidin protein core functioning as an adapter, second generation polyamidoamine dendrons for facilitating cell uptake as well as two different therapeutic proteins (tumor suppressor p53 or pro‐apoptotic cytochrome c as cargo). Well‐defined dendrons containing a biotin core are prepared and display no cytotoxic behavior upon conjugation to streptavidin. The integration of biotinylated human recombinant p53 (B‐p53) into the three component system allows excellent internalization into HeLa, A549 and SaOS osteosarcoma cells monitored via confocal microscopy, immunoblot analysis and co‐localization studies. In addition, the conjugation of B‐p53 to dendronized streptavidin preserves its specific DNA‐binding in vitro, and its delivery into SaOS cells impairs cell viability with concomitant activation of caspases 3 and 7. The versatility of this system is further exhibited by the significant enhancement of the pro‐apoptotic effects of internalized cytochrome c which is analyzed by flow cytometry and cell viability assays. These results demonstrate that the “bio‐click” self‐assembly of biotinylated dendrons and proteins on a streptavidin adapter yields a stable supramolecular complex. This efficient bionanotransporter provides an attractive platform for mediating the delivery of functional proteins of interest into living mammalian cells in a facile and rapid way.
A Novel Preparation Method for Octreotide Acetate–Loaded PLGA Microspheres with a High Drug‐Loading Capacity and a Low Initial Burst Release, and Its Studies on Relations between In Vitro and In Vivo Release
Authors: Chen Bin , Han Bing , Song Liping , Xu Dan , Pei Jin
Published: May 2013

In this study, octreotide acetate (OTA)–loaded poly(lactide‐co‐glycolide) (PLGA) microspheres were prepared using an optimized double emulsion solvent evaporation method. The loading capacity (LC) was increased by raising the concentration of OTA in the inner aqueous phase (W1), and burst release was decreased (<10.0%) because the higher viscosity hindered the diffusion of OTA. The in vitro release profiles were closely correlated with in vivo release profiles calculated using the Wagner–Nelson method (r = 0.9876). To evaluate the drug release profiles rapidly, an accelerated release method was developed. In the accelerated release method, the acidic and alkaline buffers (the first 6 h, pH 4.0; the last 18 h, pH 9.6) were used as release media, respectively. Results indicated that the accelerated release profiles (24 h) were closely correlated with the in vivo release profiles (r = 0.9623). Therefore, through optimization of the experiment variables (buffer components and pH), an accelerated release method was developed to evaluate in vivo drug release from microspheres. © 2013 Wiley Periodicals, Inc. Adv Polym Technol 2013, 32, 21354; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21354
Synthesis of a Novel Imprinted Polymeric Material for Simultaneous Recognition of Methamidophos and Acephate
Authors: Wang Xilong , Zhang Limin , Li Mingxiao , Xu Zhixiang
Published: May 2013

In this study, a novel molecularly imprinted polymer was synthesized using acephate as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross‐linker. The imprinted polymer was characterized by the static adsorption experiments, and results showed that it had higher adsorption capacity toward acephate and methamidophos than the nonimprinted polymers. Competitive experiments indicated that this material exhibited low selective recognition properties toward acephate in aqueous solution. This prepared material also offered fast kinetics for the adsorption of acephate. After shaking for 90 min, an adsorption capacity of 9.54 mg/g was obtained, and it almost reached the adsorption equilibrium within 120 min. © 2013 Wiley Periodicals, Inc. Adv Polym Technol 2013, 32, 21357; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21357
Saaty's analytic hierarchies method for knowledge organization in decision making
Authors: Rodríguez‐Bárcenas Gustavo , López‐Huertas María J.
Published: May 2013

This research studied the role of knowledge organization in the process of decision making in the field of energy efficiency and rational use of energy (EERUE). Theoretical contributions to knowledge organization and decision making are stressed. We chose to work with a type of methodology known as multiple criteria decision making—Saaty's analytical hierarchies process (AHP). This made it possible to develop a detailed analysis of the decision‐making process and arrive at a hierarchical model. The model provided a structure representing the studied field, where an order of priority could be given to the decision‐making process. The knowledge derived may be used in other fields of study such as information retrieval and knowledge representation.
On predicting the popularity of newly emerging hashtags in Twitter
Authors: Ma Zongyang , Sun Aixin , Cong Gao
Published: May 2013

Because of Twitter's popularity and the viral nature of information dissemination on Twitter, predicting which Twitter topics will become popular in the near future becomes a task of considerable economic importance. Many Twitter topics are annotated by hashtags. In this article, we propose methods to predict the popularity of new hashtags on Twitter by formulating the problem as a classification task. We use five standard classification models (i.e., Naïve bayes, k‐nearest neighbors, decision trees, support vector machines, and logistic regression) for prediction. The main challenge is the identification of effective features for describing new hashtags. We extract 7 content features from a hashtag string and the collection of tweets containing the hashtag and 11 contextual features from the social graph formed by users who have adopted the hashtag. We conducted experiments on a Twitter data set consisting of 31 million tweets from 2 million Singapore‐based users. The experimental results show that the standard classifiers using the extracted features significantly outperform the baseline methods that do not use these features. Among the five classifiers, the logistic regression model performs the best in terms of the Micro‐F1 measure. We also observe that contextual features are more effective than content features.
Set‐point weight tuning rules for fractional‐order PID controllers
Authors: Padula Fabrizio , Visioli Antonio
Published: May 2013

The problem of tuning the set‐point weight for fractional‐order proportional‐integral‐derivative (FOPID) controllers is addressed in this paper. Tuning rules are given in order to use the set‐point weight effectively for the recovering of the set‐point following performance when the FOPID controller is tuned in order to optimize the load disturbance rejection performance. Self‐regulating, integral and unstable processes are considered. Simulation results show the effectiveness of the proposed tuning rules and the comparison with integer‐order PID controllers.
Discrimination of single base mismatched oligonucleotides related to the rpoB gene of Mycobacterium tuberculosis using a surface plasmon resonance biosensor
Authors: Rachkov A. , Patskovsky S. , Soldatkin A. , Meunier M.
Published: May 2013

Single base mismatched oligonucleotides related to the rpoB gene of Mycobacterium tuberculosis, the mutations of which cause drug resistance of the infectious agent, were detected and discriminated using a surface plasmon resonance biosensor system. Thiol‐modified oligonucleotides of the selected sequence (the probe) and 1‐mercapto‐6‐hexanol were immobilized on a gold sensor surface. Hybridization between immobilized probe P2 and perfectly matched target T2 as well as a single base mismatched target TN was investigated in buffer solutions of various stringencies. Discrimination of perfectly matched and single base mismatched targets is achieved due to a difference in the level of their hybridization with the immobilized probe depending on stringency of the buffer solution. In 0.5×SSC buffer solution (7.5 mM sodium citrate, pH 7, containing 75 mM NaCl), sensor response at T2 injection into the measuring sensor cell was 16 times that at TN injection. The experimental results on surface hybridization between the studied oligonucleotides demonstrated a good correlation with theoretical calculations of thermodynamic parameters of these interactions in the solution. The described approach could be proposed as a basis for creating a biosensor for real‐time label‐free diagnostics of drug‐resistant tuberculosis.