bluuebunny/crossref_metadata_2025 huggingface dataset:
Global Properties of M31’s Stellar Halo from the SPLASH Survey. III. Measuring the Stellar Velocity Dispersion Profile∗
Authors: Gilbert Karoline M. , Tollerud Erik , Beaton Rachael L. , Guhathakurta Puragra , Bullock James S. , Chiba Masashi , Kalirai Jason S. , Kirby Evan N. , Majewski Steven R. , Tanaka Mikito
Published: January 2018

We present the velocity dispersion of red giant branch stars in M31’s halo, derived by modeling the line-of-sight velocity distribution of over 5000 stars in 50 fields spread throughout M31’s stellar halo. The data set was obtained as part of the Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo (SPLASH) Survey, and covers projected radii of 9 to 175 kpc from M31’s center. All major structural components along the line of sight in both the Milky Way (MW) and M31 are incorporated in a Gaussian Mixture Model, including all previously identified M31 tidal debris features in the observed fields. The probability that an individual star is a constituent of M31 or the MW, based on a set of empirical photometric and spectroscopic diagnostics, is included as a prior probability in the mixture model. The velocity dispersion of stars in M31’s halo is found to decrease only mildly with projected radius, from 108 km s−1 in the innermost radial bin (8.2 to 14.1 kpc) to ∼80 to 90 km s−1 at projected radii of ∼40–130 kpc, and can be parameterized with a power law of slope −0.12 ± 0.05. The quoted uncertainty on the power-law slope reflects only the precision of the method, although other sources of uncertainty we consider contribute negligibly to the overall error budget.
The Effects of Toroidal Magnetic Field on the Vertical Structure of Hot Accretion Flows
Authors: Zeraatgari Fatemeh Zahra , Mosallanezhad Amin , Abbassi Shahram , Yuan Ye-Fei
Published: January 2018

We solved the set of two-dimensional magnetohydrodynamic (MHD) equations for optically thin black hole accretion flows incorporating the toroidal component of the magnetic field. Following global and local MHD simulations of black hole accretion disks, the magnetic field inside the disk is decomposed into a large-scale field and a fluctuating field. The effects of the fluctuating magnetic field in transferring the angular momentum and dissipating the energy are described through the usual α description. We solved the MHD equations by assuming a steady-state and radially self-similar approximation in the r − θ plane of the spherical coordinate system. We found that as the amount of magnetic field at the equatorial plane increases, the heating by the viscosity decreases. In addition, the maximum amount of the heating by the viscous dissipation is produced at the midplane of the disk, while that of the heating by the magnetic field dissipation is produced at the surface of the disk. Our main conclusion is that in terms of the no-outflow solution, thermal equilibrium still exists for the strong magnetic field at the equatorial plane of the disk.
CO and Dust Properties in the TW Hya Disk from High-resolution ALMA Observations
Authors: Huang Jane , Andrews Sean M. , Cleeves L. Ilsedore , Öberg Karin I. , Wilner David J. , Bai Xuening , Birnstiel Til , Carpenter John , Hughes A. Meredith , Isella Andrea , Pérez Laura M. , Ricci Luca , Zhu Zhaohuan
Published: January 2018

We analyze high angular resolution ALMA observations of the TW Hya disk to place constraints on the CO and dust properties. We present new, sensitive observations of the 12CO J = 3 − 2 line at a spatial resolution of 8 au (0.″14). The CO emission exhibits a bright inner core, a shoulder at r ≈ 70 au, and a prominent break in slope at r ≈ 90 au. Radiative transfer modeling is used to demonstrate that the emission morphology can be reasonably reproduced with a 12CO column density profile featuring a steep decrease at r ≈ 15 au and a secondary bump peaking at r ≈ 70 au. Similar features have been identified in observations of rarer CO isotopologues, which trace heights closer to the midplane. Substructure in the underlying gas distribution or radially varying CO depletion that affects much of the disk’s vertical extent may explain the shared emission features of the main CO isotopologues. We also combine archival 1.3 mm and 870 μm continuum observations to produce a spectral index map at a spatial resolution of 2 au. The spectral index rises sharply at the continuum emission gaps at radii of 25, 41, and 47 au. This behavior suggests that the grains within the gaps are no larger than a few millimeters. Outside the continuum gaps, the low spectral index values of α ≈ 2 indicate either that grains up to centimeter size are present or that the bright continuum rings are marginally optically thick at millimeter wavelengths.
Star Formation in the Sh 2-53 Region Influenced by Accreting Molecular Filaments
Authors: Baug T. , Dewangan L. K. , Ojha D. K. , Tachihara Kengo , Pandey A. K. , Sharma Saurabh , Tamura M. , Ninan J. P. , Ghosh S. K.
Published: January 2018

We present a multiwavelength analysis of a ∼30′ × 30′ area around the Sh 2-53 region (hereafter S53 complex), which is associated with at least three H ii regions, two mid-infrared bubbles (N21 and N22), and infrared dark clouds. The 13CO line data trace the molecular content of the S53 complex in a velocity range of 36–60 km s−1 and show the presence of at least three molecular components within the selected area along this direction. Using the observed radio continuum flux of the H ii regions, the derived spectral types of the ionizing sources agree well with the previously reported results. The S53 complex harbors clusters of young stellar objects (YSOs) that are identified using the photometric 2–24 μm magnitudes. It also hosts several massive condensations (

) that are traced in the Herschel column density map. The complex is found at the junction of at least five molecular filaments, and the flow of gas toward the junction is evident in the velocity space of the 13CO data. Together, the S53 complex is embedded in a very similar “hub–filament” system to those reported in Myers, and the active star formation is evident toward the central “hub” inferred by the presence of the clustering of YSOs.
Mechanical and Fracture Characteristics of Refractory Concrete after the Action of Various Temperature Loading
Authors: Holčapek Ondřej
Published: January 2018

This article deals with the experimental investigation of residual mechanical properties of refractory composite after the action of various thermal loading. Specimens with dimension 40 × 40 × 160 mm were produced from composite containing basalt fibres and aggregate, aluminous cement and metakaolin. Different group of specimens were exposed to various temperatures 105 °C, 200 °C, 300 °C, 400 °C, 500 °C and 600 °C for three hours. Different temperature caused various changes in chemical composition of concrete that can result into decrease of mechanical properties. Bulk density, flexural strength, compressive strength, fracture energy and dynamic modulus of elasticity were investigated after each type of thermal loading. After the action of 600 °C all investigated residual properties achieved lowest values. Based on performed experiments we can conclude that the main decrease of mechanical properties take place after the action of 400 °C.
Mechanical and Basic Physical Properties of High-Strength Concrete Exposed to Elevated Temperatures
Authors: Scheinherrová Lenka , Čáchová Monika , Petříková Michaela , Fiala Lukáš , Vejmelková Eva , Grzeszczyk Stefania , Černý Robert
Published: January 2018

In this paper, the effect of elevated temperatures on the mechanical and basic properties of two different newly-designed high-strength concretes is studied. The studied materials were prepared from Portland cement, steel fibers, reactive finely milled quartz powder and quartz sand, silica fume, plasticizer, and with a relatively low water/cement ratio of 0.24. The samples were stored in water environment for the first 28 days of hydration to achieve better mechanical properties. Then, after pre-drying at 105 °C to constant mass, the materials were exposed to elevated temperatures of 600 °C and 1000 °C where they were kept for 2 hours. The basic physical properties, such as matrix density, bulk density and open porosity were determined as a function of temperature. Mechanical properties (compressive and flexural strength) were also studied. The measured parameters exhibited a high dependence on temperature and the obtained results pointed to the structural changes of the studied materials. Spalling was not observed because of the pre-drying treatment.
The Effect of Temperature on the Fundamental Characteristics of Self-Compacting No-Cement Refractory Castable
Authors: Nevřivová Lenka
Published: January 2018

In this research, the impact of firing temperature and MgO addition on mechanical and physical properties of self–compacting no-cement castables were investigated. For this propose up to 3.3 wt % of MgO was added to the corundum castable compositions and the specimens were fired at 600 °C, 800 °C, 1000°C, 1200°C and 1500°C. The mixtures were made so that the consistency of each one was the same. There were only minimal differences in the mixtures water content. The mineral composition of the input raw materials for manufacturing of the refractory castables was determined. The physical and mechanical properties of castable compositions such as self-ﬂow values, bulk density, apparent porosity, cold crushing strength and flexural strength were examined. Also, the X-ray diﬀraction (XRD) and scanning electron microscopy (SEM/EDX) techniques were used for detection the ceramic phase formation. The corrosion resistance was determined by means of the crucible test according to ČSN P CEN/TS 15418 (726022) Method of test for dense refractory products – Guidelines for testing the corrosion resistance of refractories caused by liquids. The study follows up on research, the results of which were published last year [1], but the study is focused to self-compacting refractory castable.
Dynamic Stability of Multi-Functional Composite Developed for Application in Permanent Way of Prague Underground
Authors: Kolář Karel , Litoš Jiří , Reiterman Pavel , Petrtýl Miroslav
Published: January 2018

There are described properties of hardening multi-functional silicate composite during its long-term dynamical loading in the paper. Studied composite was developed for special application in permanent way structure in Prague underground. Dynamic loading was carried out on the laboratory model, in which the composite was applied as a bench of the rail anchoring. Due to loading in early ages was also studied the option of steel fibers addition. Results obtained confirmed impressive potential for practical use during new tracks construction, and quick repairs as well, because of rapid evolution of mechanical properties and sufficient resistance to dynamic loading. Silicate composite with fibers addition had better mechanical properties, however significant improvement during dynamic loading was not recorded in comparison with the reference mixture without fibers. Generally, new composite material confirmed great potential for practical use in transportation industry.
Soft Insert for Support Modeling of Slightly Textile Reinforced Concrete
Authors: Vlach Tomáš , Laiblová Lenka , Ženíšek Michal , Řepka Jakub , Hájek Petr
Published: January 2018

This paper presents a model of small experimental facade panel using four-point bending test. The facade panel with dimensions 100 x 360 mm and thickness approximately 18 mm was slightly reinforced using two layers of impregnated technical fabric from AR-glass roving. The amount of reinforcement in cross-sectional area of the concrete element is small and it is a reason of plastic joints initiation under the loading supports. The purpose of this experiment was validation of all used material parameters from the previous research in the program for nonlinear analysis of concrete and reinforced concrete Atena Engineering. For slightly reinforced concrete elements are monitored parameters better visible especially interaction between reinforcement and used concrete. The load transfer to the concrete element from the testing machine is typically modeled using some small steel plate. This paper shows the difference in results if we insert another flexible plate between the steel plate and the concrete element with a small defined stiffness.
Optimization of the Composition of the Binder Based on CFBC Fly Ash
Authors: Formáček Petr , Šulc Rostislav
Published: January 2018

This paper is bound to previous research of materials based on fly ash. The main objective was to design an optimal ternary (three-component) binder based on fly ash from Circulating fluidized Bed Combustion (CFBC). The design of the binder is based on the optimization of individual components. Main components of the binder are CFBC fly ash, high-temperature fly ash and slaked lime. The binder was progressively designed and optimized. The strength characteristics of the various binders were measured, evaluated and the results were inserted into computer programs Surfer 8 and Grapher 8 from which ternary diagrams with strength maps were created. The best binder mixture were selected from the optimization process.
Influence of Alkalinity and Ambient Temperature on Long-Term Properties of GFRP Reinforcement
Authors: Girgle Frantisek , Bodnárová Lenka , Januš Ondřej , Kostiha Vojtech
Published: January 2018

The article deals with the current problem of determining long-term reliability of non-metallic reinforcement in concrete structures. The alkaline environment of concrete with a pH higher than 12.0 affects the glass fibres degradative, whereas this degradation presents by reduction of their mechanical characteristics, resulting in a decrease in the tensile strength of the whole composite. The article summarizes the results of the ongoing experimental program so far, which aims to quantify this influence.
Utilization of Surface-Modified Polymer and Glass Micro-Fibers as Reinforcement in Cement Composites
Authors: Trejbal Jan , Prošek Zdeněk , Fladr Josef , Tesárek Pavel
Published: January 2018

The presented work focuses on plasma modifications of polymer and glass micro-fibers (having 32 and 14 μm in the diameter, respectively) used as randomly distributed and oriented reinforcement of concrete composites. Fiber surfaces were modified by means of the low-pressure coupled cold oxygen plasma in order to attain a strong adhesion with the cement matrix. From the perspective of micro scale, an impact of modifications on both the physical and the chemical surface changes of treated fibers was examined using: (i) a wettability measurements – an evaluation of an interphase interaction between demineralized water and fibers and (ii) the SEM microscopy – an assessment of a surface morphology. From the perspective of macro scale, the interaction between the two materials was examined by destructive four-point bending tests of the cement paste containing both the reference and treated fibers (specimens having dimensions equal to 40×40×160 mm, water to cement ration 0.4) were done. It was shown that the wettability of modified fibers was increased by approx. 10 % and 70 % in the case of glass and polymer fibers, respectively. The SEM morphology analysis revealed fine roughening of treated fibers, if compared to the reference ones. The mechanical testing pointed out on a toughness increase in the post-cracking response of loaded specimens.
Utilization of Non-Traditional Fibers for Light Weight Concrete Production
Authors: Zach Jiří , Sedlmajer Martin , Bubenik Jan , Novák Vítězslav
Published: January 2018

Along with energy savings for heating and cooling, the demand for thermal insulation materials is increasing and is an attempt to achieve good thermal insulation properties for some of the construction materials. In the field of porous and lightweight concrete, this is e.g. concrete for foundations, concrete for floor constructions or flat roofs. The problem with these concrete is a relatively rapid drop in mechanical properties in reducing bulk density, with using conventional silicate binders, especially in the area below 1000 kg/m3. The paper describes the possibility of using recycled organic fibers in combination with lightweight aggregates based on foam glass for the production of porous and lightweight concrete with a good ratio of mechanical and thermal insulation properties.
An Analysis of a Tuned Mass Damper under Dynamic Loads
Authors: Sana Vladimír , Litoš Jiří , Říhová Zdeňka , Kočová Markéta
Published: January 2018

The submitted paper is focused on the design of Tuned Mass Damper in order to reduce excessive level of vibration. This device is designed to be active at the first natural frequency of the structure. Subsequently, the efficiency of the new dynamic system (structure-TMD) is verified for several types of time-dependent loads, which express swaying vandal, jumping vandal and moving pedestrian.
Retarding Action of Various Lead (II) Salts on Setting of Portland Cement
Authors: Keppert Martin
Published: January 2018

Lead is an example of heavy metal, which influences the course of silicate cement hydration resulting to retardation of setting and hardening. This topic become of importance when a cementitious material is intended to be used as solidification/stabilization matrix for a waste or secondary product containing some lead species. There are literature data on the effect of Pb retarding action but they are incomparable each other due to uneven experimental conditions, used Pb salts, types of cement etc. The present paper aims to describe influence of various lead(II) compounds (nitrate, sulfate and lead(II) oxide) on setting course of Ordinary Portland cement (OPC). The setting was monitored by Vicat apparatus, the dosage of salts (expressed as wt. % of elementary Pb to OPC) was 0.5, 1, 2 and 5%. Obviously the present anions may also influence the setting time; the set of control experiments with sodium salts of above given anions was performed in order to eliminate the anion effect. The PbO was found to be most detrimental towards retarding of setting, while lead sulfate at higher dosages caused high instability of setting (oscillation). The effect of Pb was, in all cases, more important than influence of given anion.
Synthetic Preparation and Properties of Ettringite
Authors: Fridrichová Marcela , Gazdič Dominik , Mokrá Jana , Dvořák Karel
Published: January 2018

This paper deals with the verification of the possibility of preparing synthetic ettringite in a way of direct addition of aluminum sulfate and calcium hydroxide as an alternative to the hydration of yeelimite. The stability of the resulting system was studied using the X-ray diffraction (XRD) and differential thermal analysis (DTA) in two different environments, namely in a laboratory environment and the environment of saturated water vapour. The evaluations of X-ray diffraction analysis and thermal analysis show that in the ettringite sample stored in the laboratory environment, evaporation of molecular water and subsequent transformation of ettringite into metaettringite or monosulfate can occur over time. Conversely, exposition of saturated water vapour environment can lead to saturation of the system by free calcium ions due to the slow dissociation of calcium carbonate, and thereby increase the amount of ettringite at the expense of gypsum and aluminum amorphous phase. To verify the above, it is recommended long-term monitoring of samples exposed in monitored environments.
A Simple Spot Weld Joint Finite Element Model for Vibration Analysis
Authors: Kong Yik Vui , Khandoker Noman , Lee Vincent C.C. , Islam Sumaiya
Published: January 2018

Resistance spot welding is one of the commonly used structural joining processes in sheet metal structures. This paper presents the study of vibration characteristics of a spot-welded sheet metal coupon with a simple finite element model. The finite element spot weld nugget was modelled with Spider Configuration (SC) using commercial finite element code ABAQUS. Analytically the spot welded sheet metal coupon was modeled as a free–free Euler Bernoulli beam. Comparison was made for both natural frequencies and mode shapes of the first three bending modes between finite element model and analytical model. It was found that the simple finite element model was able to predict the spot weld joint vibration characteristics with a minimum of 0.35% and a maximum of 7.3% error.
A Development of Smart Picking/Feeding System for a Production System
Authors: Wuttiwan Namrin , Prombanpong Suksan
Published: January 2018

One of the common problems in a flow line like a packing process is line breakdown. This is due to several reasons such as part shortage, equipment malfunction, etc. Especially, when parts are stored in the warehouse or in a temporary buffer area and must transport to the packing area, without good management breakdown due to part shortage easily occurs. Typically, a person who places the part and one who picks the part is not the same person and without good communication tool, waste time can be expected and causes line breakdown since the new part cannot be served in time. Thus, the objective of this paper is to demonstrate the implementation of a smart picking system and intelligent feeding schedule in order to reduce line breakdown due to part shortage. The feeding schedule is also generated for a feeding worker to replenish a pallet to the line before a buffer is running out. One of the factories is implemented as a case study where the current downtime due to part shortage is 8.2 percent and the productivity is 12.99 pieces per man-hour. A bar code system and industry tablet is used for pick and place system. Not only is the software for part location search developed, but also the feeding schedule of the whole packing line. As a result, the downtime due to part shortage is reduced to 1.2 percent and the productivity increases to 22.61 pieces per man-hour.
Analysis of Heat Generated in the Shear Zone during Machining of Titanium Alloy Ti6Al4V Using Infrared Thermal Camera
Authors: Polishetty Ashwin , Alabdullah Mohanad , Littlefair Guy
Published: January 2018

Machining represents a thermo-mechanical reaction based on factors such as plasticity, wear and friction. The experimental design consists of conducting a series of turning trials on a titanium alloy Ti6Al4V using combinations of cutting parameters namely spindle speed (n) of 770 rpm; feed rate (f) of 0.2 and 0.4 mm/rev; and depth of cut (d) of 1 and 2 mm. The length of cut (L) of 10 mm remains constant for all trials. All trails are done under dry conditions. In this paper, a detailed investigation has been carried out to study the temperature at shear zone and the effect of cutting variables on temperature has been evaluated. The temperature in shear zone for each trial was measured using an infrared thermal camera.
Improving the Purity of Multicrystalline Silicon by Using Directional Solidification Method
Authors: Li Peng Ting , Ren Shi Qiang , Wang Zi Long , Tan Yi
Published: January 2018

Large temperature gradient was introduced to improve the removal rate of metal impurity in silicon ingot during direction solidification. The concentration of metal impurities in the silicon ingot with a large temperature gradient is 0.96 ppmw. The solidification time is reduced by 20% due to the fast speed of crystal growth improved; meanwhile the purity is increased by 64%.
Improved Hardness of Nanocomposite Films on PMMA Sheet Using Beadmilled-SiO2 Nanoparticle in Dowanol PM
Authors: Lhosupasirirat Siraprapa , Jirathampradhab Taksorn , Niamsiri Nuttawee , Osotchan Tanakorn , Srikhirin Toemsak
Published: January 2018

The main objective of this study was to prepare bead milled-silica nanoparticles (SiO2) as reinforcing materials for transparent hard coating films. SiO2 dispersed in Dowanol PM without any stabilizer was used as a main component in the nanocomposite hard coating films to improve hardness of Poly methyl methacrylate (PMMA) sheets. However, the major challenge in hard coating formulation is the dispersion of nanoscale SiO2 particles. Bead milling machine (MiniCer, NETZSCH, Germany) equipped with different sizes of zirconia (ZrO2) beads (0.1, 0.5, and 1.0 mm) was used for dispersing 40wt% SiO2 in Dowanol PM to achieve target sizes of 200, 500, and 800 nm. The dispersed nanoparticles were characterized by UV-visible spectroscopy for their optical transmission, transmission electron microscopy (TEM) for particle morphologies, and dynamic light scattering technique (DLS) for the particles sizes. The milled-SiO2 nanoparticles were stable in Dowanol PM as suspensions with their particles sizes closed to the target sizes. The 200-nm suspension showed the longest storage time without any aggregate formation. Whereas, the dispersed nanoparticles suspensions with the particles size >500 nm formed agglomerates during storage. The SiO2/MTMS nanocomposite coating film was then prepared coated milled-SiO2 suspension in Dowanol PM on PMMA sheets. The film with 200 nm SiO2 showed the highest transparency (92% at 550 nm) which was like the uncoated PMMA sheets. At thickness of 3-microns, SiO2/MTMS nanocomposite films could improve pencil hardness of PMMA sheets from <H to 3H.
Thermal Performance of Lightweight Aggregate Concrete Containing Expanded Shale Aggregates
Authors: Shon Chang Seon , Mamirov Miras , Stenger Earl M. , Chung Chul Woo
Published: January 2018

Achieving energy efficiency of building in north part of Kazakhstan is very critical due to the large temperature difference during long harsh and severe winter and short hot summer seasons. Energy efficient building shows significant savings to homeowners including costs reduction from energy, water, waste, and lower operations and maintenance costs. In terms of building materials, lightweight aggregate concrete (LWAC) due to its thermal properties is often used to maintain thermal comfort levels in buildings and to reduce building energy consumption. In this paper, the potential of LWAC to improve the energy performance of building was assessed for LWAC with three different mixture proportions and a normal weight concrete (NWC) for comparison purpose. The energy saving effect of LWAC was simulated using OpenStudio software tools with an EnergyPlus engine. Moreover, annual heat loss and amount of heat transfer of construction wall of building were calculated. Results showed that LWAC can improve the energy efficiency of building and thus the use of LWAC can be a good alternative to the traditional NWC.
A Reduction of Interior Peel off Defect in a Robot Spray Coating Process
Authors: Kasorn Thanasan , Prombanpong Suksan
Published: January 2018

The Teflon coating on the hardened aluminum surface is the process of creating a film on the smooth surface which requires three layers of coating and each layer must be cured at a certain temperature. Due to a complexity of the process, peel off defect is one of the intimidate defects in the coating process. The objective of this research is, therefore to determine optimal coating parameters in order to reduce the peel off. A robot attached with a spray gun at the end effector is used to spray Teflon onto the hardened aluminum work-piece. Typically, there are three steps coating process i.e. primer, middle, and top. In this research, only the prime coating layer is studied due to the fact that the peel off defect normally occurs from this layer. A curing temperature immediately after coating is one of the root causes besides air pressure, an angle of the spray gun and fan pattern. Therefore, the experimental design technique is used to determine the relationship among these mentioned variables and identify the optimal condition. The 2k factorial is used in the experimental design and analysis of variance is used to analyze the result. It is found that the optimal condition of curing temperature at 95 degree Celsius, air pressure at 2.5 bars, a gun angle at 60 degrees, and the fan size at 5 Volt setting at the robot controller provides a better result. The peel off defect is reduced from 2.88 to 1.60 percent.
Tensile Strength of Sisal/Epoxy Composites Prepared by Vacuum Infusion
Authors: Valášek Petr
Published: January 2018

Composite systems are materials that due to its characteristics and its achievement of synergistic effects are increasingly applied. The most frequent composites are composites mainly with long fibers. In the interaction with the polymer matrix can be used inorganic fibers, but recently there is a substitution of these fibers with organic fibers. The main advantage of using organic fibers is their low cost, low weight, and availability. The benefits can also cite environmental aspects. The disadvantage is the very nature of the organic material. The paper describes a long-fiber composite system prepared by vacuum infusion and compares the tensile strength of composites with randomly oriented and arranged sisal fibers, depending on the flow direction of the resin during vacuum infusion. Composite systems were cut from boards made by vacuum infusion using a water jet. These boards are widely used by industries such as automotive or building to where the natural fibers can create design function. The use of natural fibers in this process is inexpensive and such materials can be referenced as biocomposites, saving the primary raw material. The paper describes the tensile strength and hardness. Electron microscopy was used to evaluate fracture surfaces and the morphology of the fibers.
Recombinant Human Vimentin Binds to P-Selectin and Blocks Neutrophil Capture and Rolling on Platelets and Endothelium
Authors: Lam Fong W. , Da Qi , Guillory Bobby , Cruz Miguel A.
Published: January 2018

Leukocyte adhesion to vascular endothelium and platelets is an early step in the acute inflammatory response. The initial process is mediated through P-selectin glycoprotein ligand-1 (PSGL-1) on leukocytes binding to platelets adhered to endothelium and the endothelium itself via P-selectin. Although these interactions are generally beneficial, pathologic inflammation may occur in undesirable circumstances, such as in acute lung injury (ALI) and ischemia and reperfusion injury. Therefore, the development of novel therapies to attenuate inflammation may be beneficial. In this article, we describe the potential benefit of using a recombinant human vimentin (rhVim) on reducing human leukocyte adhesion to vascular endothelium and platelets under shear stress. The addition of rhVim to whole blood and isolated neutrophils decreased leukocyte adhesion to endothelial and platelet monolayers. Furthermore, rhVim blocked neutrophil adhesion to P-selectin–coated surfaces. Binding assays showed that rhVim binds specifically to P-selectin and not to its counterreceptor, PSGL-1. Finally, in an endotoxin model of ALI in C57BL/6J mice, treatment with rhVim significantly decreased histologic findings of ALI. These data suggest a potential role for rhVim in attenuating inflammation through blocking P-selectin–PSGL-1 interactions.
Cleavage of TL1A Differentially Regulates Its Effects on Innate and Adaptive Immune Cells
Authors: Ferdinand John R. , Richard Arianne C. , Meylan Françoise , Al-Shamkhani Aymen , Siegel Richard M.
Published: January 2018

TNF superfamily cytokines play major roles in the regulation of adaptive and innate immunity. The TNF superfamily cytokine TL1A (TNFSF15), through its cognate receptor DR3 (TNFRSF25), promotes T cell immunity to pathogens and directly costimulates group 2 and 3 innate lymphoid cells. Polymorphisms in the TNFSF15 gene are associated with the risk for various human diseases, including inflammatory bowel disease. Like other cytokines in the TNF superfamily, TL1A is synthesized as a type II transmembrane protein and cleaved from the plasma membrane by metalloproteinases. Membrane cleavage has been shown to alter or abrogate certain activities of other TNF family cytokines; however, the functional capabilities of membrane-bound and soluble forms TL1A are not known. Constitutive expression of TL1A in transgenic mice results in expansion of activated T cells and promotes intestinal hyperplasia and inflammation through stimulation of group 2 innate lymphoid cells. Through the generation of membrane-restricted TL1A-transgenic mice, we demonstrate that membrane TL1A promotes expression of inflammatory cytokines in the lung, dependent upon DR3 expression on T cells. Soluble TL1A alone was unable to produce this phenotype but was still able to induce intestinal type 2 inflammation independently of T cells. These data suggest differential roles for membrane and soluble TL1A on adaptive and innate immune cells and have implications for the consequences of blocking these two forms of TL1A.
Study the antimicrobial effects of chitosan-based edible film containing the Trachyspermum ammi essential oil on shelf-life of chicken meat
Authors: Karimnezhad Fatemeh , Razavilar Vadood , Anvar Amir Ali , Eskandari Soheyl
Published: January 2018

Packaging using chitosan-based edible films incorporated with natural essential oils is a safe and economic way to increase the shelf-life and acceptability of food products and especially chicken meat. Trachyspermum ammi is a natural medicinal plant with high antimicrobial effects cultivated in Iran. The present research was done to study the antimicrobial effects of chitosan-based edible film containing T. ammi essential oil on shelf-life of chicken meat. T. ammi fruits were collected and dried. Essential oil was extracted from plants using the Clevenger’s apparatus. High molecular weight chitosan with 1% and 2% concentrations of T. ammi essential oil were used for coating of chicken fillets. Treatments were stored at 4°C for 12 days. Count of the total aerobic, total psychrophilic and coliform bacteria had ranges of 3.8±0.25 to 8.32±0.26, 4±0.23 to 8.65±0.28 and 1.8±0.09 to 5.62±0.16 CFU/g during the storage period. Antimicrobial effects were significantly increased with the incorporation of T. ammi essential oil (P<0.05). Antimicrobial effects were also depended on the concentration of T. ammi essential oil (P<0.05). Chitosan film incorporated with 2% T. ammi essential oil had the highest inhibitory effects on total aerobic, total psychrophilic and coliform bacteria (P<0.05). Our results pointed out that the incorporation of T. ammi essential oil at 2% concentration has potential for using the developed chitosan edible film as an active packaging of chicken meat.
Shiga-toxigenic Escherichia coli in ready-to-eat food staffs: Prevalence and distribution of putative virulence factors
Authors: Sakhaie Shahreza Mohammad Hossein , Rahimi Ebrahim , Momtaz Hassan
Published: January 2018

Lack of proper hygiene and using from low quality raw materials cause high presence of food-borne pathogens in ready to eat foods. Shiga toxin producing Escherichia coli is one of the most common cause of food-borne diseases in the world. The present research was done to study the prevalence and distribution of virulence factors in the STEC strains isolated from various types of ready to eat food samples. Seven-hundred and twenty food samples were collected and cultured. Isolated E. coli bacteria were approved another time using the 16S rRNA-based PCR amplification. Approved strains were subjected to multiplex PCR for identification of putative virulence factors. Twenty-six out of 720 food samples (5.20%) were positive for E. coli. Salad (15%), candy (12.50%) and barbecue (10%) were the most commonly contaminated. Prevalence of STEC strains was 2.63%. Prevalence of EHEC and AEEC subtypes were 36.84% and 52.63%, respectively. EHEC strains harbored all three stx1, eae and ehly genes. High presence of EHEC strains besides the considerable distribution of multiple virulence factors showed an important public health issue regarding the consumption of ready to eat foods.
Prevalence of antibiotic resistance and blaIMP-1 gene among Pseudomonas aeruginosa strains isolated from burn and urinary tract infections in Isfahan, central Iran
Authors: Hashemi Naeimeh Sadat , Mojiri Meysam , Yazdani Kachouyi Parivash , Eskandari Shiva , Mohammadian Mehrsa , Alavi Iman
Published: January 2018

Pseudomonas aeruginosa is one of the most important opportunistic pathogens responsible for various types of hospital infections. High prevalence of antibiotic resistance in P. aeruginosa strains of human clinical samples cause more severe diseases for a longer period of time. The current research was done in order to study the distribution of blaIMP-1 gene among the imipenem-resistant P. aeruginosa strains isolated from burn and urinary tract infections of hospitalized patients. Two-hundred and forty-three P. aeruginosa isolates recovered from the cases of burn and urinary tract infections of inpatients and outpatients were analysis for antibiotic resistance pattern using the disk diffusion method. Then, imipenem-resistant isolates were further analyzed for distribution of blaIMP-1 gene using the PCR. Of 243 P. aeruginosa isolates, 146 strains (60.08%) were taken from outpatients and 97 strains (39.91%) were taken from inpatients. P. aeruginosa isolates harbored the highest levels of resistance against streptomycin (100%), nalidixic acid (100%), aztreonam (100%), cotrimoxazole (95.47%), ciprofloxacin (88.47%), cefotaxime (84.36%) and gentamycin (83.95%). Inpatients had a relatively higher levels of antibiotic resistance. One-hundred and twenty-one out of 126 (96.03%) imipenem-resistant P. aeruginosa isolates harbored the blaIMP-1 gene. Inpatients also had a relatively higher prevalence of blaIMP-1 gene. High prevalence of blaIMP-1 gene and also imipenemresistant P. aeruginosa are important public health issue. Clinical laboratories should consider the detection of the blaIMP-1 gene among the P. aeruginosa isolates of clinical samples.
Direct transfer of genetic material between two Escherichia coli K12 strains by electroporation
Authors: Marchese Anna , Debbia Eugenio A.
Published: January 2018

A direct transfer of plasmid pBP517 from C600 to J53 Escherichia coli K12 strains by electroporation, either by the standard method, or in the presence of 20 μg/mL of DNAse was carried out. In a standard experiment, donor and recipient bacteria were mixed and subjected to the electroporation procedure, about 2700 (range 1600-3700) recombinants were found, while no colonies were detected from non treated bacteria. When the same tests were performed at the presence of DNAse the number of recombinants fell to about 200 (range 183-218). This difference between the number of colonies found in the presence or in absence of DNAse was observed every time the tests were repeated. According to these observations, plasmid DNA has been transferred from donor to recipient cells via electroporation also when DNAse was added. Since the free genetic material is destroyed by the enzyme and recombination takes place it has been hypothesized that there must be a direct contact between the partner cells.
Advection-diffusion equations with random coefficients on evolving hypersurfaces
Authors: Djurdjevac Ana
Published: January 2018

We present the analysis of advection-diffusion equations with random coefficients on moving hypersurfaces. We define a weak and a strong material derivative, which account for the spatial movement. Then we define the solution space for these kind of equations, which is the Bochner-type space of random functions defined on a moving domain. We consider both cases, uniform and log-normal distributions of the diffusion coefficient. Under suitable regularity assumptions we prove the existence and uniqueness of weak solutions of the equation under analysis, and also we give some regularity results about the solution.
Stability and asymptotic behavior of transonic flows past wedges for the full Euler equations
Authors: Chen Gui-Qiang G. , Chen Jun , Feldman Mikhail
Published: January 2018

The existence, uniqueness, and asymptotic behavior of steady transonic flows past a curved wedge, involving transonic shocks, governed by the two-dimensional full Euler equations are established. The stability of both weak and strong transonic shocks under the perturbation of the upstream supersonic flow and the wedge boundary is proved. The problem is formulated as a one-phase free boundary problem, in which the transonic shock is treated as a free boundary. The full Euler equations are decomposed into two algebraic equations and a first-order elliptic system of two equations in Lagrangian coordinates. With careful elliptic estimates by using appropriate weighted Hölder norms, the iteration map is defined and analyzed, and the existence of its fixed point is established by performing the Schauder fixed point argument. The careful analysis of the asymptotic behavior of the solutions reveals particular characters of the full Euler equations.
Adjoint inversion of Chinese non-methane volatile organic compound emissions using space-based observations of formaldehyde and glyoxal
Authors: Cao Hansen , Fu Tzung-May , Zhang Lin , Henze Daven K. , Chan Miller Christopher , Lerot Christophe , González Abad Gonzalo , De Smedt Isabelle , Zhang Qiang , Van Roozendael Michel , Chance Kelly , Li Jie , Zheng Junyu , Zhao Yuanhong
Published: January 2018

Abstract. We used the GEOS-Chem model and its adjoint to quantify Chinese non-methane volatile organic compound (NMVOC) emissions for the year 2007, using the vertical column concentrations of formaldehyde and glyoxal observed by the Global Ozone Monitoring Experiment-2A (GOME-2A) instrument and the Ozone Monitoring Instrument (OMI) as constraints. We conducted a series of inversion experiments using different combinations of satellite observations to explore the impacts on top-down emission estimates due to different satellite retrievals. Our top-down estimates for Chinese annual total NMVOC emission was 23.4 to 35.4 (average 30.8) Tg C y−1, including 13.5 to 19.7 (average 17.0) Tg C y−1 from anthropogenic sources, 8.9 to 14.8 (average 12.6) Tg C y−1 from biogenic sources, and 1.1 to 1.5 (average 1.2) Tg C y−1 from biomass burning. In comparison, the most widely-used bottom-up estimate for Chinese annual total NMVOC emission was 27.4 Tg C y−1, including 15.5 Tg C y−1 from anthropogenic sources, 10.8 Tg C y−1 from biogenic sources, and 1.1 Tg C y−1 from biomass burning. The simultaneous use of glyoxal and formaldehyde observations helped distinguish the NMVOC species from different sources and was essential in constraining anthropogenic emissions. Our four inversions consistently showed that the emissions of Chinese anthropogenic NMVOC precursors of glyoxal were larger than the a priori estimates. Our top-down estimates for the Chinese annual emission of anthropogenic aromatics (benzene, toluene, and xylene) ranged from 5.0 to 7.3 Tg C y−1, 2 % to 49 % larger than the estimate of the bottom-up inventory (4.9 Tg C y−1). Model simulations using the average of our top-down NMVOC emission estimates showed that surface afternoon ozone concentrations over northern and central China increased 5–12 ppb in June and decreased 5–13 ppb in December relative to the simulations using the a priori emissions and were in better agreement with measurements. We concluded that the satellite observations of glyoxal and formaldehyde together provided quantitative constraints on the emissions and source types of NMVOCs over China and improved our understanding on regional chemistry.
The influence of internal variability on Earth's energy balance framework and implications for estimating climate sensitivity
Authors: Dessler Andrew E. , Mauritsen Thorsten , Stevens Bjorn
Published: January 2018

Abstract. Our climate is constrained by the balance between solar energy absorbed by the Earth and terrestrial energy radiated to space. This energy balance has been widely used to infer equilibrium climate sensitivity (ECS) from observations of 20th-century warming. Such estimates yield lower values than other methods and these have been influential in pushing down the consensus ECS range in recent assessments. Here we test the method using a 100-member ensemble of the MPI-ESM1.1 climate model simulations of the period 1850–2005 with known forcing. We calculate ECS in each ensemble member using energy balance, yielding values ranging from 2.1 to 3.9 K. The spread in the ensemble is related to the central hypothesis in the energy budget framework: that global average surface temperature anomalies are indicative of anomalies in outgoing energy (either of terrestrial origin or reflected solar energy). We find that assumption is not well supported over the historical temperature record in the model ensemble or more recent satellite observations. We find that framing energy balance in terms of 500-hPa tropical temperature better describes the planet's energy balance.
A machine learning calibration model using random forests to improve sensor performance for lower-cost air quality monitoring
Authors: Zimmerman Naomi , Presto Albert A. , Kumar Sriniwasa P. N. , Gu Jason , Hauryliuk Aliaksei , Robinson Ellis S. , Robinson Allen L. ,   R. Subramanian
Published: January 2018

Abstract. Low-cost sensing strategies hold the promise of denser air quality monitoring networks, which could significantly improve our understanding of personal air pollution exposure. Additionally, low-cost air quality sensors could be deployed to areas where limited monitoring exists. However, low-cost sensors are frequently sensitive to environmental conditions and pollutant cross-sensitivities, which have historically been poorly addressed by laboratory calibrations, limiting their utility for monitoring. In this study, we investigated different calibration models for the Real-time Affordable Multi-Pollutant (RAMP) sensor package, which measures CO, NO2, O3, and CO2. We explored three methods: (1) laboratory univariate linear regression, (2) empirical multiple linear regression, and (3) machine-learning-based calibration models using random forests (RF). Calibration models were developed for 16–19 RAMP monitors (varied by pollutant) using training and testing windows spanning August 2016 through February 2017 in Pittsburgh, PA, US. The random forest models matched (CO) or significantly outperformed (NO2, CO2, O3) the other calibration models, and their accuracy and precision were robust over time for testing windows of up to 16 weeks. Following calibration, average mean absolute error on the testing data set from the random forest models was 38 ppb for CO (14 % relative error), 10 ppm for CO2 (2 % relative error), 3.5 ppb for NO2 (29 % relative error), and 3.4 ppb for O3 (15 % relative error), and Pearson r versus the reference monitors exceeded 0.8 for most units. Model performance is explored in detail, including a quantification of model variable importance, accuracy across different concentration ranges, and performance in a range of monitoring contexts including the National Ambient Air Quality Standards (NAAQS) and the US EPA Air Sensors Guidebook recommendations of minimum data quality for personal exposure measurement. A key strength of the RF approach is that it accounts for pollutant cross-sensitivities. This highlights the importance of developing multipollutant sensor packages (as opposed to single-pollutant monitors); we determined this is especially critical for NO2 and CO2. The evaluation reveals that only the RF-calibrated sensors meet the US EPA Air Sensors Guidebook recommendations of minimum data quality for personal exposure measurement. We also demonstrate that the RF-model-calibrated sensors could detect differences in NO2 concentrations between a near-road site and a suburban site less than 1.5 km away. From this study, we conclude that combining RF models with carefully controlled state-of-the-art multipollutant sensor packages as in the RAMP monitors appears to be a very promising approach to address the poor performance that has plagued low-cost air quality sensors.