bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of the Diameter of Carbon Nanotube on the Mechanical and Electrical Properties of Cement Mortar
Authors: Wang Yan Feng , Hu Hui , Rong Chui Qiang
Published: March 2017

Two different diameter carbon nanotubes were incorporated into cement mortar to investigate the effect on mechanical and electrical properties of composites. Cement-based composites have been prepared from Portland cement with various amounts of multiwall carbon nanotubes (MWCNTS), ranging from 0% to 0.3% by cement weight. In this study, effective dispersion of two different diameter MWCNTS in water were achieved by applying ultrasonic energy and in combination with the use of a surfactant. The flexural and compressive strength of mixes were investigated at age 7 and 28 days. The conductivity of composites were conducted by the four probe method at age of 3 day, 7 day,14 day and 28 day. Results indicated that the two carbon nanotubes can improve the flexural and compressive strength of the composites. Furthermore, the well dispersion carbon nanotube solutions can decrease the resistance of the composites as the better conductive networks are formed in the cement matrix, especially at the later ages. Scanning electron microscopy observation used to observe the fracture surface of specimens containing 0% and 0.3wt% nanotubes indicated that the MWCNTS were well dispersed and there were no obvious agglomerates visible in the matrix. The SEM image revealed good bonding between the MWCNTS and the surrounding matrix.
Elastic Fracture Toughness for Ductile Metal Pipes with Circumferential Surface Cracks
Authors: Li Chun Qing , Fu Guo Yang , Yang Shang Tong
Published: March 2017

Surface cracks have long been recognized as a major cause for potential failures of metal pipes. In fracture analysis, the widely used method is based on linear elastic fracture mechanics. However, for ductile metal pipes, it has been known that the existence of plasticity results in easing of stress concentration at the crack front. This will ultimately increase the total fracture toughness. Therefore, when using linear elastic fracture mechanics to predict fracture failure of ductile metal pipes, the plastic portion of fracture toughness should be excluded. Otherwise, the value of fracture toughness will be overestimated, resulting in an under-estimated probability of failure. This paper intends to derive a model of elastic fracture toughness for steel pipes with a circumferential crack. The derived elastic fracture toughness is a function of crack geometry and material properties of the cracked pipe. The significance of the derived model is that the well-established linear elastic fracture mechanics can be used for ductile materials in predicting the fracture failure.
Numerical Study of Taylor Cone Dynamics in Electrospinning of Nanofibers
Authors: Guo Hui Fen , Xu Bin Gang
Published: March 2017

Nanofibers produced by electrospinning are attractive for a large variety of applications in material science. Formation of Taylor cone is an integral part of electrospinning process. To understand deeply its formation, a two-phase electro-hydrodynamic simulation under the volume-of-fluid (VOF) model is proposed. The electric force in such systems acts only at the interface and is zero elsewhere in the two fluids. Continuum surface force (CSF) model is adopted to compute the electric field force at the interface. For the study case, transient analyses showed the moving flow fronts and their interactions with the applied electric field. Two symmetric vortices, which occur in Taylor cone, will increase the solution velocity. A beaded nanofiber can be formed owing to the beads occur in cone jet. The numerical results were consistent with previous studies. According to the numerical results, the formation mechanism and nanofiber dynamics of the Taylor cone in a multiphase flow were well disclosed for deep explanation of the process.
Calculating Mechanics Characteristics of Single-Walled Carbon Nanotube Materials by Finite Element Method
Authors: Ge Jing , Jiang Hao , Sun Zhen Yu , Yu Guo Jun , Su Bo , Sun Tiger
Published: March 2017

In this paper, we establish the mechanical property analysis of Single-walled Carbon Nanotubes (SWCNTs) modified beam element model based on the molecular structural mechanics method. Then we study the mechanical properties of their radial direction characteristics using the finite element software Abaqus. The model simulated the different bending stiffness with rectangular section beam elements C-C chemical force field. When the graphene curled into arbitrary chirality of SWCNTs spatial structure, the adjacent beam position will change the moment of inertia of the section of the beam. Compared with the original beam element model and the calculation results, we found that the established model largely reduced the overestimate of the original model of mechanical properties on the radial direction of the SWCNTs. At the same time, compared with other methods available in the literature results and the experimental data, the results can be in good agreement.
Influence of Phase Change Material Application on Photovoltaic Panel Performance
Authors: Thongtha Atthakorn , Chan Hoy Yen , Luangjok Paisit
Published: March 2017

This study investigated the application of phase change material and fins into photovoltaic panel. The experimental design was divided into 2 cases: conventional photovoltaic and photovoltaic with phase change material and fins. The thermal performance and electrical efficiency was tested under the solar radiation simulator between 500 and 1000 W/m2. The insolation intensity was tested by an incident-light photometer. The power of the nine halogen lamps was controlled by a simple voltage control device. It was found that temperature of normal PV module is constant after the tested time of 20 minutes. The temperatures of PV module with phase change material and fins were lower than a normal PV module throughout the testing duration. Approximately 2-6% of photovoltaic module temperatures have decreased and this have improved the electrical efficiency of about 1-4%. This indicated the use of phase change material and fins is able to decrease the photovoltaic module temperature and thus increase the efficiency of photovoltaic module cooling.
Development of Sunlight LED Bollard Based on C/GFRP Floodlight Composite
Authors: Shin Hyung Gon , Oh Je Ha , Byun Dong Hae , Choi Hyoung Chul
Published: March 2017

It is safe and light because it uses carbon/glass fiber reinforced plastics (hereinafter referred to as C/GFRP) through this technological development. Moreover, sunlight LED luminous bollard, which was harmonized with the surrounding environment with diverse colors, was developed. Luminous bollard can reduce its weight and also increase its strength by adjusting the intensity and thickness of a product customized for each usage on the basis of the characteristics of C/GFRP composite. In addition, C/GFRP and steel pipe were compared for the compression test in order to compare the objective rigidity. As a result, this study could obtain a positive result graph of luminous bollard. To develop luminous bollard, the composite development process was configured through a fixture of pullout and filament winding. Diverse colors can be applied to luminous bollard. Hence, it is possible to select a color customized for each region. It is also possible to create an aesthetic harmony with a surrounding environment through LED lamps at night. The pipe, which was 50 percent lighter than stainless and also which had excellent tensile strength, was designed to develop the bollard that has superior convenience in terms of construction, maintenance and repair.
Analysis of the Application of Piezoelectric Ceramic Material in the De-Icing Technique of the Aircrafts
Authors: Li Qing Ying , ZHU Yong Jiu
Published: March 2017

The application of piezoelectric ceramic material in de-icing technique of aircrafts is presented in numerical simulation and experiment methods. Firstly, the ice properties are introduced briefly as the evaluation of device design. Then, modal simulation of the testing skin of NACA 0030 is performed to determine the position where the piezoelectric ceramics fix. The resonance frequency as the driving frequency in the experiment is calculated in harmonic analysis with the actuators bonding on the testing skin model. Moreover, piezoelectric de-icing rig is fabricated as the modeling results. It is shown that the driving frequency agrees well with the calculated resonance frequency, and the ice can be removed when the driving frequency is 1530 Hz and the driving voltage is 650 V. In addition, design factors as material properties, size of the ceramics, and excitation voltage are discussed. From the numerical calculation, the stress will vary with different piezoelectric ceramic materials and sizes of the ceramics. It will decrease with the increase of thickness of the piezoelectric ceramics, but increase linearly with the increase of the voltage. Therefore it is considerable to choose design parameters for piezoelectric de-icing systems.
Evaluation of Measurement Uncertainty for Polymer Thin Film Humidity Sensor Using CMH and PRT Based on Dew Point Temperature Variation
Authors: Bae Yun Kyung , Lee Dong Eun , Hyun Dong Hoon
Published: March 2017

The purpose of this paper is to propose appropriate evaluation method of measurement uncertainty with respect to the measurement results of polymer thin film capacitive humidity sensor according to dew point temperature variation. All of the evaluation process concerning the measurement uncertainty of polymer thin film capacitive humidity sensor is based on experiment and numerical analysis. To estimate uncertainty contribution properly for polymer thin film capacitive sensor strongly influenced by measurement environment, the experiments are performed in the reference relative humidity range from 5 % to 30 % at a setting dry bulb temperature of 23°C. Also, the reference standards are chilled mirror hygrometer (CMH) and platinum resistance thermometer (PRT). In particular, the uncertainty sources are considered differently according to the range of below or above 0°C, reference dew point. From the budgets, uncertainty contributions to the standard uncertainty are clearly dominated by the effect of the uncertainty due to super-cooling in case of condition below 0°C, dew point temperature. Also, the contributions for stability and distribution of humidity generator have a mainly effect on the expanded uncertainty of polymeric humidity sensor. It is desired that measurement uncertainties of polymeric humidity sensor are comprised separately on the basis of reference dew point, 0°C. The evaluation procedure of measurement uncertainty is developed in accordance with the principles established in the documents EA-4/02, Expression of the Uncertainty of Measurement in Calibration [1].
Fabrication and Construction of Floating Photovoltaic Energy Generation Structures Using Fiber Reinforced Polymer Plastic (FRP) Members
Authors: Kim Sun Hee , Won Yong Seok , Seo Su Hong , Park Joo Kyung , Yoon Soon Jong
Published: March 2017

In this paper, we present the result of investigations pertaining to the floating photovoltaic energy generation structures. Pultruded fiber reinforced polymer plastics (PFRP) and sheet molding compound (SMC) fiber reinforced polymer plastics (FRP) have superior mechanical and physical properties compared with those of conventional structural materials. Fiber reinforced polymer plastics (FRP) has an excellent corrosion resistance and high specific strength and stiffness, the FRP material may be highly appreciated for the floating photovoltaic energy generation system. The floating photovoltaic energy generation system is analyzed and designed to have sufficient safety. In addition, from the finite element analysis the safety of the structure was also confirmed. Based on the results, structural system is designed, fabricated, and installed at the site.
The Preparation and Testing of Rheological Properties for Single- and Double-Grading Magnetorheological Composite Gels
Authors: Guo Fei , Lin Xiao Guo , Yu Guo Jun
Published: March 2017

The modified carbonyl iron powders with single particle size (single-grading) and binary particle sizes (double-grading) were added in the composite gel, which was prepared by using methyl silicone oil, gelatin and agaropectin colloids as raw materials, and then the single-and double-grading magnetorheological composite gels (MRCGs) were prepared by vacuum decompression. The effects of particle size and gradation of carbonyl iron power on the rheological behavior of the MRCGs were studied. The results show that the shear strength of single-grading MRCGs decreased gradually with the decrease of the carbonyl iron particle size. However that the shear strength of the double-grading MRCGs with the gradation of 90 wt% un-ball-milled and 10 wt% ball-milled carbonyl iron powders first increased then decreased with the elongation of milling time (the decrease of carbonyl iron paticle size) and reached 99.6kPa when ball milling time for 24h, which was 17.8kPa larger than that of un-ball-milled single-grading MRCGs.
Effect of Rapid Thermal Annealing on the Structural Evolution and Electrical Property of Gold Films Deposited on Silicon
Authors: Janardhanam V. , Choi Chel Jong
Published: March 2017

An investigation of the electrical and microstructural properties of gold (Au)/p-type silicon (Si) contact was performed as a function of rapid thermal annealing (RTA) temperatures. Au films reacted with Si and produced Au2Si and Au3Si phases during the deposition of the films at room temperature. The electrical properties of the Au contact to p-type Si degraded with increasing RTA temperature. Such a degradation of the electrical properties could be associated with the degradation of the surface and interface morphology caused by the formation of Au-silicide clusters. The RTA process at 500 °C led to an increase in the size of the Au-silicide Island. This led to the further degradation of the electrical properties after annealing at 500 °C.
Grid Indentation and Statistic Deconvolution: Limitations and Accuracy
Authors: Hrbek Vladimír , Koudelková Veronika
Published: March 2017

The evaluation of heterogeneous materials used in civil engineering on the microscopic level has become important aspect in proper understanding of the macroscopic behavior of the material. This contribution aims at advantages and problems related to the technique of grid indentation and at the evaluation of mechanical properties.
The Dependence of Concentration Copper Ions in Nanofibers (PVA) on Composition of Original Basic Electrospin Solution and on Kind of Stabilization
Authors: Havrlík Michal , Ryparová Pavla
Published: March 2017

The nanofiber textile was made by electrospinning on device Nanospider LB 500 (Elmarco, CR). The original basic polymer solution contains polyvinyl alcohol and additional supplement: a glyoxal and phosphoric acid for thermal stabilization and copper sulphate as a biotic agent. The concentration of copper sulphate pentahydrate (CuSO4·5H2O) in original basic polymer solution was 0.5 and 1% and it follows that the theoretical concentration of copper ions in nanofibers was 0.95 and 1.89%. Subsequently the nanofibers had stabilized by thermal heat (140 °C, 10 min), and by chemical cross linking methods with using of soaking in solution with glutaraldehyde, methanol. The stabilized nanofibers were characterized by scanning electron microscope (SEM) and atomic absorption spectrum (AAS). The results showed that the thermal stabilization did not change nanostructures too much, but subsequent soaking showed, that their structure has changed after 24 hour leaching, the crosslinked points has not sharp line. This measurement leads to conclusion, that the stabilization by heat is not fully absolute. Chemical stabilization nanofibers by glutaraldehyde changed the nanoproperties only in range a few percent and the solubility in water was absolutely completed. The stabilization by methanol has destroyed nanostructures of the fabrics, and the nanofiber textile looks like thin layer or thick membrane. The nanostructures didn't change their character nor after water soaking. The content of copper in nanofiber had measured by (AAS) and thus proved that the copper concentration in nanofiber is independent on original concentration in solution. The next results from this measurement confirm the assumption that the concentrations of copper are dependent on kind stabilization. The next results from this measurement confirm the assumption that the concentrations of copper are dependent on kind stabilization. The stabilization by soaking in stabilization solution leads to decrease of concentration of copper in nanofiber. The thermal stabilization didn't change final content of copper in nanofiber, the stabilization by glutaraldehyde changed the concentration, it was lower by 2 mg/g and the stabilization by methanol made nanofiber with one quarter original value of copper.
Hydration Heat Evolution of the Cement Paste with Recycled Concrete: Influence of Grain Size Distribution of Recycled Concrete Powder
Authors: Topič Jaroslav , Prošek Zdeněk
Published: March 2017

The paper deals with the influence of level of grinding of the recycled concrete. Level of grinding mostly influence the hydration heat evolution of cement paste. Measurement of hydration heat evolution is one of the ways to detect reactive properties of recycled concrete powder modified by high speed mill device. Basic characteristics that most influence the hydraulic properties of recycled concrete powder are grin size diagram and chemical composition of the original concrete. Non-hydrated inner part of cement grains could further react if it is exposed to water. In this experiment the recycled concrete from recycled railroad sleepers and structural layers of the D2 highway was used. Recycled concrete powder from highway was divided into 4 more variants which differ by grinding process during production. To detect difference in hydration process four mixtures of cement paste with different types of recycled concrete powder were made and further subjected to calorimetric measurement. The results were after compared with the hydration heat rate of reference cement paste. According to results the type of milling process had minor influence on hydraulic properties of recycled concrete powder compared with influence of origin of recycled concrete.
Water-Resistance of Nanofiber Textiles
Authors: Černohorský Martin , Havrlík Michal
Published: March 2017

This work deals with the determination of basic waterproofing properties of nanofiber textiles with basis weights of up to 30 g/m2. Samples used in this experiment were made from nanofiber textiles based on two polymers – PVDF and PUR. Each polymer was prepared in three basis weights. All samples were not treated prior to testing. One of the key properties was the contact angle of water and the resistance to penetration of liquid water. Water-resistance of nanofiber textiles was tested according to the harmonized European standard EN 13859-1., Underlays for discontinuous roofing in pitched roof constructions are tested according to this standard. In the position of underlays there has to be some layer with low diffusion resistance of water vapor and relatively high waterproofing. We suppose such properties of nanofiber textiles. Testing of the two groups of material basis shows correlation between the contact angle and water-resistance of the nanofiber textile.
Moisture Survey of Former Convent in the Vicinity of Prague Castle
Authors: Řehák Jakub , Burgetová Eva , Řehák Josef
Published: March 2017

During the detailed moisture survey of the former convent the historical drainage and ventilation systems were found and documented. This paper describes an interesting discovery in the basement of the monastery and presents conceptual design of remediation pointing out, at the same time, the risk factors. Methods using new materials including nanostructures are also mentioned.
Shrinkage of Cement Composite with Material Based on Waste Marble and Limestone
Authors: Hlubocký Lukáš , Prošek Zdeněk
Published: March 2017

The article deals with the shrinkage of a cement composite with various contents of waste micronized limestone powder with a fraction size of 0-63 μm and crushed limestone with a fraction size of 0-2 mm. Waste micronized powder is produced by high-speed grinding of marble sludge. The difference in shrinkage of various mixtures has been described by means of structural analysis. Electron microscopy has been used for this analysis. Mixtures with 10 wt. % of cement and various ratios of micronized marble powder to crushed limestone (1: 1; 1: 2; 2: 1; 1: 0) were investigated. The increasing amount of waste micronized powder adversely affects the shrinkage of the cement composite. This effect is caused by the increasing water–cement ratio for the purpose of achieving the same workability of the mixture.
Influence of Different Fillers in Polymer Matrix of Single Roving on the Tensile Properties
Authors: Vlach Tomáš , Laiblová Lenka , Hájek Petr
Published: March 2017

Technical textiles and composite materials in general becomes more and more popular for the reinforcing of concrete elements. These materials are very often combined with high performance fine grain concretes with big surface quality. High performance concretes developed rapidly in the last decade and therefore also composite materials must be developed hand in hand with concrete. One possibility is to further imrove basic material or roving itself, but this article is focused on improving of the polymer matrix. As a matrix in this presented article was used epoxy resin. The purpose of the experiment was to improve the tensile parameters of composite reinforcement by adding fillers into the matrix. Fillers improve interaction between individual fibers and thatks to that improve parameters of entire composite.
Influence of Sever Plastic Deformation on the Consolidation Behavior of Al-SiC Mixed Powder
Authors: Qian Chen Hao , Li Ping , Xue Ke Min , Liu Hong Li
Published: March 2017

Abstract: Oxidized and non-oxidized SiC particulates were mixed with Al powder respectively and the two kinds of mixed powders were consolidated at 250°C by equal channel angular pressing and torsion (ECAP-T), which belongs to severe plastic deformation. The interfacial bondings of as-consolidated composites were characterized by SEM images, corrosion morphology and fracture morphology. The results show that after severe plastic deformation, the interfacial bonding between non-oxidized SiC and Al is a kind of mechanical bonding and the consolidation is not firm enough so that the composite has a weak corrosion resistance and its tensile sample has a brittle fracture. However, the composite containing oxidized SiC has a dense microstructure, high corrosion resistance, ductile fracture due to the metallurgical interface.
Consolidation of Mechanically Alloyed Cu-Zr-Ti Metallic Glass Powders
Authors: Lin Chung Kwei , Lee Pee Yew
Published: March 2017

In the present study, Cu60Zr30Ti10 metallic glass powders were prepared by mechanical alloying of pure Cu, Zr, and Ti powder mixtures. Cu60Zr30Ti10 metallic glass composite powders were obtained after 5 h of milling as confirmed by X-ray diffraction and transmission electron microscopy. The metallic glass powders were found to exhibit a supercooled liquid region before crystallization. Cu60Zr30Ti10 bulk metallic glass were synthesized by vacuum hot pressing the as-milled Cu60Zr30Ti10 metallic glass powders at 723 K in the pressure range of 0.72 ~ 1.20 GPa. Cu60Zr30Ti10 BMG with nanocrystalline precipitates homogeneously embedded in a highly dense glassy matrix was successfully prepared under applied pressures. It was found that the pressure could enhance the thermal stability and prolong the existence of amorphous phase inside Cu60Zr30Ti10 powders.
Microstructure and Properties of Fe-B-C Cast Wear-Resistant Alloy
Authors: Huang Zhi Fu , Xing Jian Dong , Ma Sheng Qiang , Gao Yi Min , Zheng Ming , Sun Li Qiu
Published: March 2017

The microstructure, toughness, hardness and wear resistance of Fe-B-C cast wear-resistant alloy were studied. The results indicate that, the as-cast Fe-B-C alloy comprises pearlite, ferrite and eutectic phase Fe2 (B, C), and that, with increasing boron and carbon contents, the boride volume fraction (BVF) and macrohardness increase; furthermore, when boron content increases from about 0.5 wt.% to 2.0 wt.%, the increase trend of the macrohardness will become smaller with increasing the carbon content. The results also indicate that, after heat-treatment, the Fe2 (B, C) becomes coarser than that as cast condition, and the boron content has less effect on the martensite hardness at the same carbon content; with increasing boron and carbon contents, the hardness of the samples increases and inversely the toughness decreases. At a lower BVF, the matrix plays a dominant role on the impact toughness of Fe-B-C alloy; however, at a higher BVF, the BVF plays a dominant role. The wear test results indicate that, with increasing the boron and carbon contents, the weight loss of the samples decreases, namely, the increase of wear resistance.
The Influence of the Heating Method on the Microstructure Evolution of Thermal Deformed TA15 Titanium Alloy
Authors: Li Ping , Yao Peng Peng , Xue Ke Min , Gan Guo Qiang
Published: March 2017

X-ray diffraction and EBSD techniques were applied to investigate microstructure evolution and phase transition of thermal deformed TA15 titanium alloy under different heating methods(β phase zone heating and conventional heating). The results indicate that microstructures of thermal deformed TA15 titanium alloy after water quenching appear grain refinement undergoing these two kinds of heating methods. A large number of primary equiaxed α grains are retained after two phase zone deformation under conventional heating method. Meanwhile more regular arrangement and greater cluster of acicular plate martensite microstructure and clear original β grains are obtained through β phase deformation and water quenching. The diffraction peak of (200) crystal face of Al-rich α phase disappears under β phase zone heating method. The preferential orientation of TA15 titanium alloy after thermal deformation and water quenching is reduced obviously under β phase zone heating method.
Trial of a Novel Intervention to Improve Multiple Food Hygiene Behaviors in Nepal
Authors: Gautam Om Prasad , Schmidt Wolf-Peter , Cairncross Sandy , Cavill Sue , Curtis Valerie
Published: March 2017

In this study, we report on the results of a trial of an intervention to improve five food hygiene behaviors among mothers of young children in rural Nepal. This novel intervention targeted five behaviors; cleanliness of serving utensils, handwashing with soap before feeding, proper storage of cooked food, and thorough reheating and water treatment. Based on formative research and a creative process using the Behavior-Centered Design approach, an innovative intervention package was designed and delivered over a period of 3 months. The intervention activities included local rallies, games, rewards, storytelling, drama, competitions linking with emotional drivers of behavior, and “kitchen makeovers” to disrupt behavior settings. The effect of the package on behavior was evaluated via a cluster-randomized before–after study in four villages with four villages serving as controls. The primary outcome was the difference in the mean cluster level proportions of mothers directly observed practicing all five food hygiene behaviors. The five targeted food hygiene behaviors were rare at baseline (composite performance of all five behaviors in intervention 1% [standard deviation (SD) = 2%] and in control groups 2% [SD = 2%]). Six weeks after the intervention, the target behaviors were more common in the intervention than in the control group (43% [SD = 14%] versus 2% [SD = 2%], P = 0.02) during follow-up. The intervention appeared to be equally effective in improving all five behaviors in all intervention clusters. This study shows that a theory-driven, systematic approach employing emotional motivators and modifying behavior settings was capable of substantially improving multiple food hygiene behaviors in Nepal.
Comparison of Cytokine Responses in Ecuadorian Children Infected with Giardia, Ascaris, or Both Parasites
Authors: Weatherhead Jill , Cortés Andrea Arévalo , Sandoval Carlos , Vaca Maritza , Chico Martha , Loor Sophia , Cooper Philip J. , Mejia Rojelio
Published: March 2017

More than 2 billion people are infected with parasites globally, and the majority have coinfections. Intestinal protozoa and helminths induce polarizing CD4+ T-helper cell 1 (Th1) mediated cytokine responses within the host. Such immune polarization may inhibit the ability of the host to mount an adequate immune response for pathogen clearance to concurrent pathogens. The current study evaluated the plasma cytokine profile in Ascaris and Giardia coinfected children compared with Giardia- and Ascaris-only infected children. Fecal samples and blood samples were collected from asymptomatic 3-year-old children living in the district of Quininde, Ecuador. Stool samples that tested positive for Giardia lamblia-only, Ascaris lumbricoides-only, or G. lamblia and A. lumbricoides coinfections were confirmed by quantitative real-time polymerase chain reaction. Plasma samples from the study subjects were used to quantitate cytokines. A total of 39 patients were evaluated. Children with coinfection had a significant decrease in Th1 cytokine production, interleukin 2 (IL-2) (P < 0.05), IL-12 (P < 0.05), and tumor necrosis factor alpha (P < 0.05) compared with Giardia-only infected children. Coinfected children had an increase in IL-10/interferon gamma (IFN-γ) ratio compared with uninfected (P < 0.05) and Ascaris alone (P < 0.05). The increased IL-10/IFN-γ ratio in the setting of decreased Th1 cytokine response indicates Th2 polarization in the coinfected group. Reduced Th1 cytokines in children coinfected with Ascaris and Giardia may impair the host's ability to eradicate Giardia infection leading to chronic giardiasis.
MONITOR Ionospheric Network: two case studies on scintillation and electron content variability
Authors: Béniguel Yannick , Cherniak Iurii , Garcia-Rigo Alberto , Hamel Pierrick , Hernández-Pajares Manuel , Kameni Roland , Kashcheyev Anton , Krankowski Andrzej , Monnerat Michel , Nava Bruno , Ngaya Herbert , Orus-Perez Raül , Secrétan Hughes , Sérant Damien , Schlüter Stefan , Wilken Volker
Published: March 2017

Abstract. The ESA MONITOR network is composed of high-frequency-sampling global navigation satellite systems (GNSS) receivers deployed mainly at low and high latitudes to study ionosphere variability and jointly with global GNSS data and ionospheric processing software in support of the GNSS and its satellite-based augmentation systems (SBAS) like the European EGNOS. In a recent phase of the project, the network was merged with the CNES/ASECNA network and new receivers were added to complement the latter in the western African sector. This paper summarizes MONITOR, presenting two case studies on scintillations (using almost 2 years of data measurements). The first case occurred during the major St. Patrick's Day geomagnetic storm in 2015. The second case study was performed in the last phase of the project, which was supported by ESA EGNOS Project Office, when we paid special attention to extreme events that might degrade the system performance of the European EGNOS.
Neodymium isotopes in the ocean model of the Community Earth System Model (CESM1.3)
Authors: Gu Sifan , Liu Zhengyu , Jahn Alexandra , Rempfer Johannes , Zhang Jiaxu , Joos Fortunat
Published: March 2017

Abstract. Neodymium (Nd) isotope ratio (εNd) is a quasi-conservative water mass tracer and has been used increasingly as paleoclimate proxy to indicate the past evolution of ocean circulation. However, there are many uncertainties in interpreting εNd reconstructions. For the purposes of direct comparison between climate models and proxy reconstructions, we implement Nd isotopes (143Nd and 144Nd) in the ocean model of the Community Earth System Model (CESM). Two versions of Nd tracers are implemented: one is the "abiotic" Nd in which the particle fields are prescribed as the particle climatology generated by the marine ecosystem module of the CESM under present day forcing; the other is the "biotic" Nd that is coupled with the marine ecosystem module. Under present day climate forcing, our model is able to simulate both Nd concentrations and εNd in good agreement with available observations. Also, Nd concentration and εNd in our model show similar sensitivities to the total boundary source and the ratio between particle related Nd and dissolved Nd as in previous modeling study (Rempfer et al., 2011). Therefore, our Nd-enabled ocean model provides a promising tool to study past changes in ocean and climate.
Soil organic carbon stocks are systematically overestimated by misuse of the parameters bulk density and rock fragment content
Authors: Poeplau Christopher , Vos Cora , Don Axel
Published: March 2017

Abstract. Estimation of soil organic carbon (SOC) stocks requires estimates of the carbon content, bulk density, rock fragment content and depth of a respective soil layer. However, different application of these parameters could introduce a considerable bias. Here, we explain why three out of four frequently applied methods overestimate SOC stocks. In soils rich in rock fragments (> 30 vol. %), SOC stocks could be overestimated by more than 100 %, as revealed by using German Agricultural Soil Inventory data. Due to relatively low rock fragments content, the mean systematic overestimation for German agricultural soils was 2.1–10.1 % for three different commonly used equations. The equation ensemble as re-formulated here might help to unify SOC stock determination and avoid overestimation in future studies.
INFLUÊNCIA DO USO DA TERRA EM VARIÁVEIS LIMNOLÓGICAS NA MICROBACIA HIDROGRÁFICA DO ARROIO ALBERTI – SÃO JOÃO DO POLÊSINE/RS
Authors: Alberti Edison Antonio , Pereira Filho Waterloo
Published: March 2017

O objetivo geral deste trabalho é analisar a interação do uso da terra com variáveis limnológicas na microbacia hidrográfica do arroio Alberti, localizado no município de São João do Polêsine / RS. Para atingir este objetivo, o canal principal do rio foi dividido em cinco seções com base na geomorfologia e acesso ao local, a fim de definir os pontos de coleta de água em cada seção. A classificação do uso da terra foi obtida a partir de uma imagem do sensor ETM+ do satélite LANDSAT 7. Para a identificação do uso da terra foram definidas as seguintes classes: floresta, campo, agricultura, água e área urbana. As variáveis limnológicas utilizadas foram: condutividade elétrica, pH, temperatura da água e total de sólidos em suspensão. As análises destas variáveis permitiram identificar que os diferentes usos da terra proporcionam ambientes diferenciados ao longo do arroio com reflexo em todas as variáveis limnológicas. As variáveis pH e total de sólidos em suspensão foram mais intensamente dependente do uso da terra. Os valores mais alterados destas variáveis foram constatados justamente nos pontos amostrais localizados junto ao núcleo urbano de São João do Polêsine, reflexo das intervenções antrópicas.
ESTUDOS TAXONÔMICOS DA FAMÍLIA SALICACEAE MIRB. NA CAATINGA SUBLITORÂNEA DA PARAÍBA?
Authors: Cordeiro Joel Maciel Pereira , Almeida Erton Mendonça , Felix Leonardo Pessoa
Published: March 2017

A Caatinga sublitorânea na Paraíba corresponde a uma estreita faixa de vegetação que abriga características de transição entre a Mata Atlântica e a Caatinga interiorana. Apesar de bastante diversa e ao mesmo tempo complexa, a mesma apresenta-se pouco estudada do ponto de vista florístico. A família Salicaceae nesta região, assim como na Paraíba como um todo, aparece mencionada em poucos levantamentos florísticos e, mesmo assim, com diversos gêneros de identificação imprecisa. Desta forma, o presente trabalho objetiva realizar um levantamento da família Salicaceae na Caatinga sublitorânea da Paraíba, com elaboração de chaves de identificação, descrições taxonômicas e ilustrações dos táxons registrados. Foram descritas quatro espécies de Salicaceae, distribuídas em três gêneros, sendo o gênero Casearia com duas espécies. As descrições taxonômicas aqui apresentadas contribuíram para um maior conhecimento da família Salicaceae na Paraíba e no Nordeste brasileiro, e forneceu ainda uma maior compreensão de determinados gêneros e táxons desta família, tendo em vista que o gênero Prockia e as espécies Prockia crucis, Casearia hirsuta e Xylosma prockia não aparecem mencionados em estudos taxonômicos para as Salicaceae no Brasil.
QUANTIFICAÇÃO E DISTRIBUIÇÃO ESPACIAL DE ELEMENTOS GEOQUÍMICOS EM UMA ÁREA AGRÍCOLA NO MUNICÍPIO DE IGUARAÇU - PR
Authors: Becegato Valter Antonio , Oliveira Josiani Córdova , Becegato Vitor Rodolfo , Simioni Flávio José
Published: March 2017

A presente pesquisa foi realizada em uma área agrícola submetida a plantio direto, localizada no Noroeste do estado do Paraná entre as coordenadas UTM 417.750 e 420.000 m E, 7.428.250 e 7.431.250 m N. Utilizou-se 77 pontos amostrais de solos para duas profundidades: 0-20 e 20-40 cm, totalizando 154 amostras, com o objetivo de analisar as seguintes variáveis geoquímicas: argila, pH, fósforo (P), potássio (K), matéria orgânica, cálcio (Ca), magnésio (Mg), cobre (Cu), zinco (Zn), ferro (Fe) e manganês (Mn). Foram identificados e mapeados os seguintes solos: Nitossolo Vermelho Eutrófico; Latossolo Vermelho Eutroférrico e Latossolo Vermelho Distroférrico. Os maiores valores geoquímicos obtidos para a profundidade de 0-20 cm foi para as variáveis:  pH, Ca, Mg,  Zn, Fe e Mn. Para a profundidade de 20-40 cm foi à argila. Os resultados obtidos devem ser considerados na definição de planos de amostragem do solo, bem como, no manejo da adubação da referida área, através da análise do alcance e das variabilidades horizontal e vertical dos atributos geoquímicos estudados.
PRODUÇÃO DE SEDIMENTOS E ASSOREAMENTO EM RESERVATÓRIO NO SEMIÁRIDO: O CASO DO AÇUDE MARENGO, CEARÁ
Authors: Batista Lopes José Wellington , De Araújo Neto José Ribeiro , Pinheiro Everton Alves Rodrigues
Published: March 2017

O assoreamento de reservatórios é um processo que merece bastante atenção no semiárido cearense, visto que, o abastecimento hídrico dessa região dar-se basicamente das águas superficiais. No presente artigo propõe-se uma aplicação do modelo USLE associado ao SIG para estimativa da distribuição espacial da erosão, bem como, a quantificação do assoreamento em um reservatório de águas superficiais no estado do Ceará, o açude Marengo localizado no município de Madalena. A bacia hidrográfica possui uma área de 74,6 km2, sendo a capacidade de armazenamento do reservatório de 18,5 hm3. O levantamento batimétrico foi utilizado a fim de verificar o grau de aproximação dos resultados simulados aos dados medidos. Portanto, foram simulados outros três cenários: i) 60 anos após a construção, sendo esse o cenário utilizado na aferição do modelo; ii) 100 anos e iii) 200 anos. A distribuição da perda de solo em quase 70% da bacia do reservatório apresenta valor menor que 50 t ha-1 ano-1, sendo considerada como grau moderado de erosão. A produção de sedimento média para a bacia foi de 5,22 t ha-1 ano-1. O volume assoreado médio anual foi da ordem de 0,028 hm3 ano-1 resultando em uma taxa moderada de assoreamento da ordem de 0,15% ao ano. Verificou-se que curva cota- volume medida a partir da batimetria, está próxima à curva estimada pelo modelo no mesmo período de tempo, mostrando a robustez do modelo USLE+SIG na estimativa do assoreamento.
CARTOGRAFIA DO PASSADO: MEMÓRIAS COLETIVAS E FOTOINTERPRETAÇÃO DA COMUNIDADE LAGEADO GRANDE, CAMPO LARGO – PR
Authors: Michalczyszyn Michell , Staniski Adelita , Bertolino Alessandro
Published: March 2017

Este trabalho buscou conhecer o território pretérito da comunidade Lageado Grande no município de Campo Largo, Paraná, a partir da produção de um mapa participativo e outro mapa elaborado por meio da interpretação de uma imagem aérea da mesma região. O mapa participativo foi construído por meio da lembrança, aproximadamente 35 anos atrás, constituindo uma cartografia da representação da memória, com moradores da região. O segundo mapa, fruto da fotointerpretação, utiliza como referência uma fotografia aérea, monocromática, do ano de 1980. O mapeamento participativo tem feito uso das tecnologias de geoprocessamento e técnicas da cartografia e pode ser entendido como uma possibilidade de resgatar os conhecimentos tradicionais. Quanto aos resultados, comparando visualmente os mapas apresentam diferenças quanto ao número de classes. Enquanto o mapa participativo apontou 10 classes de usos da terra, o mapa da fotointerpretação adotou uma divisão em apenas 4 classes. Juntos os dois mapas ampliam a visão e possibilitam um mapeamento mais completo do local estudado
ANÁLISE DO USO E COBERTURA DA TERRA EM DECORRÊNCIA DA EXPANSÃO DO CULTIVO DE EUCALIPTO NO MUNICÍPIO DE SELVÍRIA/MS
Authors: São Miguel Angélica Estigarribia , Medeiros Rafael Brugnolli , De Oliveira Wallace
Published: March 2017

O presente trabalho tem como objetivo, elaborar uma análise de uso e cobertura vegetal no município de Selvíria/BRASIL, que possui uma área de 3256,25km². Para a preparação da pesquisa foi elaborado um mapeamento da evolução do uso e cobertura da terra nos anos de 2000, 2008 e 2014. Para o mapeamento, foram utilizadas imagens do satélite Landsat 5 TM, processadas com o auxilio do software SPRING 5.0.6 – INPE e Landsat 8 OLI, conforme classificação proposta pelo manual de uso e ocupação da terra do IBGE (2013). Como resultados, observaram-se rápidas transformações da paisagem devido à expansão do setor florestal que vem acompanhada da substituição da vegetação existente na região por pastagens e cultivo de eucalipto. Concluiu-se que o município de Selvíria/BRASIL está se tornando um atrativo de grandes empresas para o cultivo de florestas plantadas, hoje contando com grandes empresas deste setor e de forma geral, esse cultivo tem adentrado várias áreas como de pastagens e áreas florestais.
The Effect of Using WhatsApp Messenger in Learning English Language among University Students
Authors: Ta'amneh Mohammad Abd Alhafeez Ali
Published: March 2017

This study aimed to find the effect of using "WhatsApp messenger" in learning English language among university students during the academic year 2015/2016. The participants of the study consisted of 40 first year university students. They were divided into two groups. The control group consisted of 21 students taught in a traditional way while the experimental group consisted of 19 students taught through using a combination between WhatsApp and traditional learning. The results of this study showed that there were differences in the achievements of the students in the experimental group and the control group. This difference was in favor of the experimental group. The differences between the two groups indicated that integrating the WhatsApp application in teaching English language improved the abilities of the learners of the experimental group.
Children’s felicitous use of intersubjective particles evidences sensitivity to constellations of perspectives
Authors: Boeg Thomsen Ditte
Published: March 2017

Discourse particles specify how interlocutors’ understandings converge and differ, and appropriate use requires ability to represent propositions from two perspectives simultaneously. This makes discourse particles a highly useful case for investigating developments in children’s ability to monitor and compare mental states, a controversial issue in child language research. Being neither salient, nor obligatory, the particles further allow us to assess children’s motivation to look for interpersonal meanings without strong linguistic incentives. By means of a corpus analysis of peer group conversations (123 hours, 19 children: 1;9–6;3 years), the present study examines at which ages Danish kindergarteners demonstrate stable mastery of the interpersonal contextual demands of five particles marking shared knowledge, disagreement and differential access to knowledge. As background for evaluating children’s particle use as well as order of occurrence, adult consensus on particle meanings was substantiated with a gap-filling test and relative input frequency estimated in caregiver speech. Children were significantly above chance in producing intersubjective particles in felicitous contexts and differentiated clearly between the particles. While there was a strong increase in token frequency over the kindergarten years, children evidenced sensitivity to context from their first productions, and particle felicity did not improve significantly with higher age or production experience. The results suggest that 3-to-6-year-olds routinely monitor and compare representational states, and that they are highly motivated to coordinate conversations as joint actions by pointing to interlocutor perspectives.This article is part of Special Collection: Perspective Taking
Latent class analysis of acceptability and willingness to pay for self‐HIV testing in a United States urban neighbourhood with high rates of HIV infection
Authors: Nunn Amy , Brinkley‐Rubinstein Lauren , Rose Jennifer , Mayer Kenneth , Stopka Thomas , Towey Caitlin , Harvey Julia , Santamaria Karina , Sabatino Kelly , Trooskin Stacey , Chan Philip A.
Published: March 2017

Introduction: Acceptability and willingness to both take and pay for HIV self‐tests (HIVSTs) in US neighbourhoods with high rates of HIV infection are not well understood.

Methods: We surveyed 1,535 individuals about acceptability and willingness to take and pay for an HIVST in a predominately African American neighbourhood with 3% HIV seroprevalence. We recruited individuals presenting for HIV screening services in a community‐based programme. Latent class analysis (LCA) grouped individuals with similar patterns of HIV‐risk behaviours and determined which groups would be most willing to use and buy HIVSTs.

Results: Nearly 90% of respondents were willing to use an HIVST; 55% were willing to buy HIVSTs, but only 23% were willing to pay the market price of US $40. Four distinct groups emerged and were characterized by risk behaviours: (1) low risk (N = 324); (2) concurrent partnerships (N = 346); (3) incarceration and substance use (N = 293); and (4) condomless sex/multiple partners (N = 538). Individuals in the low‐risk class were less willing to self‐test compared to concurrent sexual partners (OR = 0.39, p = .003) and incarceration and substance use (OR = 0.46, p = .011) classes. There were no significant differences across classes in the amount individuals were willing to pay for an HIVST.

Conclusions: HIVSTs were overwhelmingly acceptable but cost prohibitive; most participants were unwilling to pay the market rate of US $40. Subsidizing and implementing HIVST programmes in communities with high rates of infection present a public health opportunity, particularly among individuals reporting condomless sex with multiple partners, concurrent sexual partnerships and those with incarceration and substance use histories.