The composition of M-type asteroids: Synthesis of spectroscopic and radar observations

NASA Astrophysics Data System (ADS)

Neeley, J. R.; Ockert-Bell, M. E.; Clark, B. E.; Shepard, M. K.; Cloutis, E. A.; Fornasier, S.; Bus, S. J.

2011-10-01

This work updates our and expands our long term radar-driven observational campaign of 27 main-belt asteroids (MBAs) focused on Bus-DeMeo Xc- and Xk-type objects (Tholen X and M class asteroids) using the Arecibo radar and NASA Infrared Telescope Facilities (IRTF). Seventeen of our targets were near-simultaneously observed with radar and those observations are described in companion paper (Shepard et al., 2010). We utilized visible wavelength for a more complete compositional analysis of our targets. Compositional evidence is derived from our target asteroid spectra using three different methods: 1) a χ2 search for spectral matches in the RELAB database, 2) parametric comparisons with meteorites and 3) linear discriminant analysis. This paper synthesizes the results of the RELAB search, parametric comparisons, and linear discriminant analysis with compositional suggestions based on radar observations. We find that for six of seventeen targets with radar data, our spectral results are consistent with their radar analog (16 Psyche, 21 Lutetia, 69 Hesperia, 135 Hertha, 216 Kleopatra, and 497 Iva). For twenty out of twenty-seven objects our statistical comparisons with RELAB meteorites result in consistent analog identification, providing a degree of confidence in our parametric methods.

Antiplane shear wave propagation in fiber-reinforced composites.

PubMed

Kim, Jin-Yeon

2003-05-01

A self-consistent method for analyzing antiplane shear wave propagation in two-dimensional inhomogeneous media is presented. For applications in the high-frequency range, the self-consistent condition for the effective medium is solved being supplemented with the theory of quasidynamic effective density. Comparisons with other theoretical calculations and experimental data for fiber-reinforced composites demonstrate the merits of using the present method.

Comparison of Methods for Assessing Body Composition Changes during Weight Loss.

ERIC Educational Resources Information Center

Weyers, Anna M.; Mazzetti, Scott A.; Love, Dawn M.; Gomez, Ana L.; Kraemer, William J.; Volek, Jeff S.

2002-01-01

Investigated whether dual-energy x-ray absorptiometry (DXA) and air displacement plethysmography (ADP) would detect similar changes in body composition after moderate weight loss. Twenty adults had their body composition measured using DXA and ADP before and after an 8-week weight loss program. Overall, both DXA and ADP detected similar changes in…

In search of best fitted composite model to the ALAE data set with transformed Gamma and inversed transformed Gamma families

NASA Astrophysics Data System (ADS)

Maghsoudi, Mastoureh; Bakar, Shaiful Anuar Abu

2017-05-01

In this paper, a recent novel approach is applied to estimate the threshold parameter of a composite model. Several composite models from Transformed Gamma and Inverse Transformed Gamma families are constructed based on this approach and their parameters are estimated by the maximum likelihood method. These composite models are fitted to allocated loss adjustment expenses (ALAE). In comparison to all composite models studied, the composite Weibull-Inverse Transformed Gamma model is proved to be a competitor candidate as it best fit the loss data. The final part considers the backtesting method to verify the validation of VaR and CTE risk measures.

Comparison of base composition analysis and Sanger sequencing of mitochondrial DNA for four U.S. population groups.

PubMed

Kiesler, Kevin M; Coble, Michael D; Hall, Thomas A; Vallone, Peter M

2014-01-01

A set of 711 samples from four U.S. population groups was analyzed using a novel mass spectrometry based method for mitochondrial DNA (mtDNA) base composition profiling. Comparison of the mass spectrometry results with Sanger sequencing derived data yielded a concordance rate of 99.97%. Length heteroplasmy was identified in 46% of samples and point heteroplasmy was observed in 6.6% of samples in the combined mass spectral and Sanger data set. Using discrimination capacity as a metric, Sanger sequencing of the full control region had the highest discriminatory power, followed by the mass spectrometry base composition method, which was more discriminating than Sanger sequencing of just the hypervariable regions. This trend is in agreement with the number of nucleotides covered by each of the three assays. Published by Elsevier Ireland Ltd.

Estimation of Metal Acceleration by an SF5 Containing Explosive

DTIC Science & Technology

1991-06-30

cylinder wall acceleration, the wall energies for the baseline composition and for the composition CW2 were calculated by three different methods : KSM, 6...computaticno! method to calculate the cylinder energies needed for comparison with expermental data, it was decided to compare data from three known methods ...detonation pressure given for the GAB method in Reference 8. They are E(6mm) = 0.1272 (Isp X density)1 .5 - 0.021, and E(l9mm) = 0.1580 (Isp x density) 1 .5

ICAN: A versatile code for predicting composite properties

NASA Technical Reports Server (NTRS)

Ginty, C. A.; Chamis, C. C.

1986-01-01

The Integrated Composites ANalyzer (ICAN), a stand-alone computer code, incorporates micromechanics equations and laminate theory to analyze/design multilayered fiber composite structures. Procedures for both the implementation of new data in ICAN and the selection of appropriate measured data are summarized for: (1) composite systems subject to severe thermal environments; (2) woven fabric/cloth composites; and (3) the selection of new composite systems including those made from high strain-to-fracture fibers. The comparisons demonstrate the versatility of ICAN as a reliable method for determining composite properties suitable for preliminary design.

Comparison of the abundance and composition of litter fauna in tropical and subalpine forests

Treesearch

G. Gonzalez; T.R. Seastedt

2000-01-01

In this study, we quantify the abundance and composition of the litter fauna in dry and wet tropical forests and north- and south-facing subalpine forests. We used the same litter species contained in litterbags across study sites to standardize for substrate conditions, and a single method of fauna extraction from the litter (Tullgren method). Fauna densities were...

Environmental justice assessment for transportation : risk analysis

DOT National Transportation Integrated Search

1999-04-01

This paper presents methods of comparing populations and their racial/ethnic compositions using tabulations, histograms, and Chi Squared tests for statistical significance of differences found. Two examples of these methods are presented: comparison ...

Compositional analysis of biomass reference materials: Results from an interlaboratory study

DOE PAGES

Templeton, David W.; Wolfrum, Edward J.; Yen, James H.; ...

2015-10-29

Biomass compositional methods are used to compare different lignocellulosic feedstocks, to measure component balances around unit operations and to determine process yields and therefore the economic viability of biomass-to-biofuel processes. Four biomass reference materials (RMs NIST 8491–8494) were prepared and characterized, via an interlaboratory comparison exercise in the early 1990s to evaluate biomass summative compositional methods, analysts, and laboratories. Having common, uniform, and stable biomass reference materials gives the opportunity to assess compositional data compared to other analysts, to other labs, and to a known compositional value. The expiration date for the original characterization of these RMs was reached andmore » an effort to assess their stability and recharacterize the reference values for the remaining material using more current methods of analysis was initiated. We sent samples of the four biomass RMs to 11 academic, industrial, and government laboratories, familiar with sulfuric acid compositional methods, for recharacterization of the component reference values. In this work, we have used an expanded suite of analytical methods that are more appropriate for herbaceous feedstocks, to recharacterize the RMs’ compositions. We report the median values and the expanded uncertainty values for the four RMs on a dry-mass, whole-biomass basis. The original characterization data has been recalculated using median statistics to facilitate comparisons with this data. We found improved total component closures for three out of the four RMs compared to the original characterization, and the total component closures were near 100 %, which suggests that most components were accurately measured and little double counting occurred. Here, the major components were not statistically different in the recharacterization which suggests that the biomass materials are stable during storage and that additional components, not seen in the original characterization, were quantified here.« less

An Investigation into the Application of Generalized Differential Quadrature Method to Bending Analysis of Composite Sandwich Plates

NASA Astrophysics Data System (ADS)

Ghassemi, Aazam; Yazdani, Mostafa; Hedayati, Mohamad

2017-12-01

In this work, based on the First Order Shear Deformation Theory (FSDT), an attempt is made to explore the applicability and accuracy of the Generalized Differential Quadrature Method (GDQM) for bending analysis of composite sandwich plates under static loading. Comparative studies of the bending behavior of composite sandwich plates are made between two types of boundary conditions for different cases. The effects of fiber orientation, ratio of thickness to length of the plate, the ratio of thickness of core to thickness of the face sheet are studied on the transverse displacement and moment resultants. As shown in this study, the role of the core thickness in deformation of these plates can be reversed by the stiffness of the core in comparison with sheets. The obtained graphs give very good results due to optimum design of sandwich plates. In Comparison with existing solutions, fast convergent rates and high accuracy results can be achieved by the GDQ method.

Faecal indicator bacteria enumeration in beach sand: a comparison study of extraction methods in medium to coarse sands.

PubMed

Boehm, A B; Griffith, J; McGee, C; Edge, T A; Solo-Gabriele, H M; Whitman, R; Cao, Y; Getrich, M; Jay, J A; Ferguson, D; Goodwin, K D; Lee, C M; Madison, M; Weisberg, S B

2009-11-01

The absence of standardized methods for quantifying faecal indicator bacteria (FIB) in sand hinders comparison of results across studies. The purpose of the study was to compare methods for extraction of faecal bacteria from sands and recommend a standardized extraction technique. Twenty-two methods of extracting enterococci and Escherichia coli from sand were evaluated, including multiple permutations of hand shaking, mechanical shaking, blending, sonication, number of rinses, settling time, eluant-to-sand ratio, eluant composition, prefiltration and type of decantation. Tests were performed on sands from California, Florida and Lake Michigan. Most extraction parameters did not significantly affect bacterial enumeration. anova revealed significant effects of eluant composition and blending; with both sodium metaphosphate buffer and blending producing reduced counts. The simplest extraction method that produced the highest FIB recoveries consisted of 2 min of hand shaking in phosphate-buffered saline or deionized water, a 30-s settling time, one-rinse step and a 10 : 1 eluant volume to sand weight ratio. This result was consistent across the sand compositions tested in this study but could vary for other sand types. Method standardization will improve the understanding of how sands affect surface water quality.

Telescoping Mechanics: A New Paradigm for Composite Behavior Simulation

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Murthy, P. L. N.; Gotsis, P. K.; Mital. S. K.

2004-01-01

This report reviews the application of telescoping mechanics to composites using recursive laminate theory. The elemental scale is the fiber-matrix slice, the behavior of which propagates to laminate. The results from using applications for typical, hybrid, and smart composites and composite-enhanced reinforced concrete structures illustrate the versatility and generality of telescoping scale mechanics. Comparisons with approximate, single-cell, and two- and three-dimensional finite-element methods demonstrate the accuracy and computational effectiveness of telescoping scale mechanics for predicting complex composite behavior.

COMPARISON OF FIVE EXTRACTION METHODS ON INCURRED AND FORTIFIED PESTICIDES IN COMPOSITE DIETS: BLENDER, SOXHLET, ASE, MICROWAVE AND SFE

EPA Science Inventory

The USEPA National Exposure Research Laboratory studies dietary exposure to a diverse group of semi-volatile pesticides by analyzing 24 hour duplicate composite diets. The pesticides of interest include organochlorines, organophosphates, anilines, and triazines. Currently, there ...

Comparison of Chemical Composition of Complex Disinfection Byproduct (DBP) Mixtures Produced by Different Treatment Methods - slides

EPA Science Inventory

Analyses of the chemical composition of complex DBP mixtures, produced by different drinking water treatment processes, are essential to generate toxicity data required for assessing their risks to humans. For mixture risk assessments, whole mixture toxicology studies generally a...

Comparison of Chemical Composition of Complex Disinfection Byproduct (DBP) Mixtures Produced by Different Treatment Methods

EPA Science Inventory

Analyses of the chemical composition of complex DBP mixtures, produced by different drinking water treatment processes, are essential to generate toxicity data required for assessing their risks to humans. For mixture risk assessments, whole mixture toxicology studies generally a...

Accelerated, microwave-assisted, and conventional solvent extraction methods affect anthocyanin composition from colored grains.

PubMed

Abdel-Aal, El-Sayed M; Akhtar, Humayoun; Rabalski, Iwona; Bryan, Michael

2014-02-01

Anthocyanins are important dietary components with diverse positive functions in human health. This study investigates effects of accelerated solvent extraction (ASE) and microwave-assisted extraction (MAE) on anthocyanin composition and extraction efficiency from blue wheat, purple corn, and black rice in comparison with the commonly used solvent extraction (CSE). Factorial experimental design was employed to study effects of ASE and MAE variables, and anthocyanin extracts were analyzed by spectrophotometry, high-performance liquid chromatography-diode array detector (DAD), and liquid chromatography-mass spectrometry chromatography. The extraction efficiency of ASE and MAE was comparable with CSE at the optimal conditions. The greatest extraction by ASE was achieved at 50 °C, 2500 psi, 10 min using 5 cycles, and 100% flush. For MAE, a combination of 70 °C, 300 W, and 10 min in MAE was the most effective in extracting anthocyanins from blue wheat and purple corn compared with 50 °C, 1200 W, and 20 min for black rice. The anthocyanin composition of grain extracts was influenced by the extraction method. The ASE extraction method seems to be more appropriate in extracting anthocyanins from the colored grains as being comparable with the CSE method based on changes in anthocyanin composition. The method caused lower structural changes in anthocaynins compared with the MAE method. Changes in blue wheat anthocyanins were lower in comparison with purple corn or black rice perhaps due to the absence of acylated anthocyanin compounds in blue wheat. The results show significant differences in anthocyanins among the 3 extraction methods, which indicate a need to standardize a method for valid comparisons among studies and for quality assurance purposes. © 2014 Her Majesty the Queen in Right of Canada Journal of Food Science © 2014 Institute of Food Technologists® Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.

Structural health monitoring in composite materials using frequency response methods

NASA Astrophysics Data System (ADS)

Kessler, Seth S.; Spearing, S. Mark; Atalla, Mauro J.; Cesnik, Carlos E. S.; Soutis, Constantinos

2001-08-01

Cost effective and reliable damage detection is critical for the utilization of composite materials in structural applications. Non-destructive evaluation techniques (e.g. ultrasound, radiography, infra-red imaging) are available for use during standard repair and maintenance cycles, however by comparison to the techniques used for metals these are relatively expensive and time consuming. This paper presents part of an experimental and analytical survey of candidate methods for the detection of damage in composite materials. The experimental results are presented for the application of modal analysis techniques applied to rectangular laminated graphite/epoxy specimens containing representative damage modes, including delamination, transverse ply cracks and through-holes. Changes in natural frequencies and modes were then found using a scanning laser vibrometer, and 2-D finite element models were created for comparison with the experimental results. The models accurately predicted the response of the specimems at low frequencies, but the local excitation and coalescence of higher frequency modes make mode-dependent damage detection difficult and most likely impractical for structural applications. The frequency response method was found to be reliable for detecting even small amounts of damage in a simple composite structure, however the potentially important information about damage type, size, location and orientation were lost using this method since several combinations of these variables can yield identical response signatures.

Weighting and Aggregation in Composite Indicator Construction: A Multiplicative Optimization Approach

ERIC Educational Resources Information Center

Zhou, P.; Ang, B. W.; Zhou, D. Q.

2010-01-01

Composite indicators (CIs) have increasingly been accepted as a useful tool for benchmarking, performance comparisons, policy analysis and public communication in many different fields. Several recent studies show that as a data aggregation technique in CI construction the weighted product (WP) method has some desirable properties. However, a…

Manufacturing Methods and Technology Project Summary Reports

DTIC Science & Technology

1984-06-01

was selected as the composite material. This selection was based upon the following advantages in comparison to aluminum: 0 Stiffness to weight...closer to titanium than aluminum. Other composite candidate materials considered ( glass , Kevlar and metal matrix) did not offer all of these...of the bearing support ring, and the attachment of the bearing support ring to the composite gimbal base plate. A thermal test structure, which

Advanced composites: Fabrication processes for selected resin matrix materials

NASA Technical Reports Server (NTRS)

Welhart, E. K.

1976-01-01

This design note is based on present state of the art for epoxy and polyimide matrix composite fabrication technology. Boron/epoxy and polyimide and graphite/epoxy and polyimide structural parts can be successfully fabricated. Fabrication cycles for polyimide matrix composites have been shortened to near epoxy cycle times. Nondestructive testing has proven useful in detecting defects and anomalies in composite structure elements. Fabrication methods and tooling materials are discussed along with the advantages and disadvantages of different tooling materials. Types of honeycomb core, material costs and fabrication methods are shown in table form for comparison. Fabrication limits based on tooling size, pressure capabilities and various machining operations are also discussed.

Design, ancillary testing, analysis and fabrication data for the advanced composite stabilizer for Boeing 737 aircraft. Volume 1: Technical summary

NASA Technical Reports Server (NTRS)

Aniversario, R. B.; Harvey, S. T.; Mccarty, J. E.; Parsons, J. T.; Peterson, D. C.; Pritchett, L. D.; Wilson, D. R.; Wogulis, E. R.

1983-01-01

The horizontal stabilizer of the 737 transport was redesigned. Five shipsets were fabricated using composite materials. Weight reduction greater than the 20% goal was achieved. Parts and assemblies were readily produced on production-type tooling. Quality assurance methods were demonstrated. Repair methods were developed and demonstrated. Strength and stiffness analytical methods were substantiated by comparison with test results. Cost data was accumulated in a semiproduction environment. FAA certification was obtained.

MUSIC imaging method for electromagnetic inspection of composite multi-layers

NASA Astrophysics Data System (ADS)

Rodeghiero, Giacomo; Ding, Ping-Ping; Zhong, Yu; Lambert, Marc; Lesselier, Dominique

2015-03-01

A first-order asymptotic formulation of the electric field scattered by a small inclusion (with respect to the wavelength in dielectric regime or to the skin depth in conductive regime) embedded in composite material is given. It is validated by comparison with results obtained using a Method of Moments (MoM). A non-iterative MUltiple SIgnal Classification (MUSIC) imaging method is utilized in the same configuration to locate the position of small defects. The effectiveness of the imaging algorithm is illustrated through some numerical examples.

Compression-based distance (CBD): a simple, rapid, and accurate method for microbiota composition comparison

PubMed Central

2013-01-01

Background Perturbations in intestinal microbiota composition have been associated with a variety of gastrointestinal tract-related diseases. The alleviation of symptoms has been achieved using treatments that alter the gastrointestinal tract microbiota toward that of healthy individuals. Identifying differences in microbiota composition through the use of 16S rRNA gene hypervariable tag sequencing has profound health implications. Current computational methods for comparing microbial communities are usually based on multiple alignments and phylogenetic inference, making them time consuming and requiring exceptional expertise and computational resources. As sequencing data rapidly grows in size, simpler analysis methods are needed to meet the growing computational burdens of microbiota comparisons. Thus, we have developed a simple, rapid, and accurate method, independent of multiple alignments and phylogenetic inference, to support microbiota comparisons. Results We create a metric, called compression-based distance (CBD) for quantifying the degree of similarity between microbial communities. CBD uses the repetitive nature of hypervariable tag datasets and well-established compression algorithms to approximate the total information shared between two datasets. Three published microbiota datasets were used as test cases for CBD as an applicable tool. Our study revealed that CBD recaptured 100% of the statistically significant conclusions reported in the previous studies, while achieving a decrease in computational time required when compared to similar tools without expert user intervention. Conclusion CBD provides a simple, rapid, and accurate method for assessing distances between gastrointestinal tract microbiota 16S hypervariable tag datasets. PMID:23617892

Compression-based distance (CBD): a simple, rapid, and accurate method for microbiota composition comparison.

PubMed

Yang, Fang; Chia, Nicholas; White, Bryan A; Schook, Lawrence B

2013-04-23

Perturbations in intestinal microbiota composition have been associated with a variety of gastrointestinal tract-related diseases. The alleviation of symptoms has been achieved using treatments that alter the gastrointestinal tract microbiota toward that of healthy individuals. Identifying differences in microbiota composition through the use of 16S rRNA gene hypervariable tag sequencing has profound health implications. Current computational methods for comparing microbial communities are usually based on multiple alignments and phylogenetic inference, making them time consuming and requiring exceptional expertise and computational resources. As sequencing data rapidly grows in size, simpler analysis methods are needed to meet the growing computational burdens of microbiota comparisons. Thus, we have developed a simple, rapid, and accurate method, independent of multiple alignments and phylogenetic inference, to support microbiota comparisons. We create a metric, called compression-based distance (CBD) for quantifying the degree of similarity between microbial communities. CBD uses the repetitive nature of hypervariable tag datasets and well-established compression algorithms to approximate the total information shared between two datasets. Three published microbiota datasets were used as test cases for CBD as an applicable tool. Our study revealed that CBD recaptured 100% of the statistically significant conclusions reported in the previous studies, while achieving a decrease in computational time required when compared to similar tools without expert user intervention. CBD provides a simple, rapid, and accurate method for assessing distances between gastrointestinal tract microbiota 16S hypervariable tag datasets.

Faecal indicator bacteria enumeration in beach sand: A comparison study of extraction methods in medium to coarse sands

USGS Publications Warehouse

Boehm, A.B.; Griffith, J.; McGee, C.; Edge, T.A.; Solo-Gabriele, H. M.; Whitman, R.; Cao, Y.; Getrich, M.; Jay, J.A.; Ferguson, D.; Goodwin, K.D.; Lee, C.M.; Madison, M.; Weisberg, S.B.

2009-01-01

Aims: The absence of standardized methods for quantifying faecal indicator bacteria (FIB) in sand hinders comparison of results across studies. The purpose of the study was to compare methods for extraction of faecal bacteria from sands and recommend a standardized extraction technique. Methods and Results: Twenty-two methods of extracting enterococci and Escherichia coli from sand were evaluated, including multiple permutations of hand shaking, mechanical shaking, blending, sonication, number of rinses, settling time, eluant-to-sand ratio, eluant composition, prefiltration and type of decantation. Tests were performed on sands from California, Florida and Lake Michigan. Most extraction parameters did not significantly affect bacterial enumeration. anova revealed significant effects of eluant composition and blending; with both sodium metaphosphate buffer and blending producing reduced counts. Conclusions: The simplest extraction method that produced the highest FIB recoveries consisted of 2 min of hand shaking in phosphate-buffered saline or deionized water, a 30-s settling time, one-rinse step and a 10 : 1 eluant volume to sand weight ratio. This result was consistent across the sand compositions tested in this study but could vary for other sand types. Significance and Impact of the Study: Method standardization will improve the understanding of how sands affect surface water quality. ?? 2009 The Society for Applied Microbiology.

Post-Buckling and Ultimate Strength Analysis of Stiffened Composite Panel Base on Progressive Damage

NASA Astrophysics Data System (ADS)

Zhang, Guofan; Sun, Xiasheng; Sun, Zhonglei

Stiffened composite panel is the typical thin wall structure applied in aerospace industry, and its main failure mode is buckling subjected to compressive loading. In this paper, the development of an analysis approach using Finite Element Method on post-buckling behavior of stiffened composite structures under compression was presented. Then, the numerical results of stiffened panel are obtained by FE simulations. A thorough comparison were accomplished by comparing the load carrying capacity and key position strains of the specimen with test. The comparison indicates that the FEM results which adopted developed methodology could meet the demand of engineering application in predicting the post-buckling behavior of intact stiffened structures in aircraft design stage.

A systematic comparison of recurrent event models for application to composite endpoints.

PubMed

Ozga, Ann-Kathrin; Kieser, Meinhard; Rauch, Geraldine

2018-01-04

Many clinical trials focus on the comparison of the treatment effect between two or more groups concerning a rarely occurring event. In this situation, showing a relevant effect with an acceptable power requires the observation of a large number of patients over a long period of time. For feasibility issues, it is therefore often considered to include several event types of interest, non-fatal or fatal, and to combine them within a composite endpoint. Commonly, a composite endpoint is analyzed with standard survival analysis techniques by assessing the time to the first occurring event. This approach neglects that an individual may experience more than one event which leads to a loss of information. As an alternative, composite endpoints could be analyzed by models for recurrent events. There exists a number of such models, e.g. regression models based on count data or Cox-based models such as the approaches of Andersen and Gill, Prentice, Williams and Peterson or, Wei, Lin and Weissfeld. Although some of the methods were already compared within the literature there exists no systematic investigation for the special requirements regarding composite endpoints. Within this work a simulation-based comparison of recurrent event models applied to composite endpoints is provided for different realistic clinical trial scenarios. We demonstrate that the Andersen-Gill model and the Prentice- Williams-Petersen models show similar results under various data scenarios whereas the Wei-Lin-Weissfeld model delivers effect estimators which can considerably deviate under commonly met data scenarios. Based on the conducted simulation study, this paper helps to understand the pros and cons of the investigated methods in the context of composite endpoints and provides therefore recommendations for an adequate statistical analysis strategy and a meaningful interpretation of results.

Comparison of hand laid-up tape and filament wound composite cylinders and panels with and without impact damage

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.; Lopez, Osvaldo F.

1991-01-01

Experimentally determined axial compressive failure loads, strains and failure modes of composite flat panels and cylinders are presented. A comparison of two types of filament wound flat graphite-epoxy panels indicates that the winding pattern can influence structural response. A comparison of hand laid-up tape and filament wound composite cylinders indicates that fabrication method may not significantly influence the failure mode or average failure strain of thick-walled (radius-to-thickness ratio less than 15) graphite-epoxy cylinders. The interaction of manufacturing-induced features (fiber cross-overs) and low-speed impact damage for graphite-epoxy specimens is also presented. Filament would flat panels with many fiber cross-overs exhibited lower failure strains than filament wound panels without fiber cross-overs for all impact speeds examined. Graphite-thermoplastic cylinders exhibited a significantly different failure mode from the graphite-epoxy cylinders.

Composite synchronization of three eccentric rotors driven by induction motors in a vibrating system

NASA Astrophysics Data System (ADS)

Kong, Xiangxi; Chen, Changzheng; Wen, Bangchun

2018-03-01

This paper addresses the problem of composite synchronization of three eccentric rotors (ERs) driven by induction motors in a vibrating system. The composite synchronous motion of three ERs is composed of the controlled synchronous motion of two ERs and the self-synchronous motion of the third ER. Combining an adaptive sliding mode control (ASMC) algorithm with a modified master-slave control structure, the controllers are designed to implement controlled synchronous motion of two ERs with zero phase difference. Based on Lyapunov stability theorem and Barbalat's lemma, the stability of the designed controllers is verified. On basis of controlled synchronization of two ERs, self-synchronization of the third ER is introduced to implement composite synchronous motion of three ERs. The feasibility of the proposed composite synchronization method is analyzed by numerical method. The effects of motor and structure parameters on composite synchronous motion are discussed. Experiments on a vibrating test bench driven by three ERs are operated to validate the effectiveness of the proposed composite synchronization method, including a comparison with self-synchronization method.

Microgravity processing of particulate reinforced metal matrix composites

NASA Technical Reports Server (NTRS)

Morel, Donald E.; Stefanescu, Doru M.; Curreri, Peter A.

1989-01-01

The elimination of such gravity-related effects as buoyancy-driven sedimentation can yield more homogeneous microstructures in composite materials whose individual constituents have widely differing densities. A comparison of composite samples consisting of particulate ceramics in a nickel aluminide matrix solidified under gravity levels ranging from 0.01 to 1.8 G indicates that the G force normal to the growth direction plays a fundamental role in determining the distribution of the reinforcement in the matrix. Composites with extremely uniform microstructures can be produced by these methods.

Comparison of individual, pooled, and composite fecal sampling methods for detection of Salmonella on U.S. dairy operations

USDA-ARS?s Scientific Manuscript database

The objectives of this study were to estimate the prevalence of Salmonella for individual, pooled, and composite fecal samples and to compare culture results from each sample type for determining herd Salmonella infection status and identifying Salmonella serotype(s). The USDA’s National Animal Hea...

Standard methods for filled hole tension testing of textile composites

NASA Technical Reports Server (NTRS)

Portanova, M. A.; Masters, J. E.

1995-01-01

The effects of two test specimen geometry parameters, the specimen width and W/D ratio, on filled-hole tensile strength were determined for textile composite materials. Test data generated by Boeing and Lockheed on 2-D and 3-D braids, and 3-D weaves were used to make these evaluations. The investigation indicated that filled-hole tensile-strength showed little sensitivity to either parameter. Test specimen configurations used in open-hole tension tests, such as those suggested by ASTM D5766 - Standard Test Method for Open Hole Tensile Strength of Polymer Matrix Composite Laminates or those proposed by MIL-HDBK-17-lD should provide adequate results for material comparisons studies. Comparisons of the materials' open-hole and filled-hole tensile strengths indicated that the latter were generally lower than the former. The 3-D braids were the exception; their filled-hole strengths were unexpected larger than their open-hole strengths. However, these increases were small compared to the scatter in the data. Thus, filled hole tension may be a critical design consideration for textile composite materials.

Simulation of guided-wave ultrasound propagation in composite laminates: Benchmark comparisons of numerical codes and experiment.

PubMed

Leckey, Cara A C; Wheeler, Kevin R; Hafiychuk, Vasyl N; Hafiychuk, Halyna; Timuçin, Doğan A

2018-03-01

Ultrasonic wave methods constitute the leading physical mechanism for nondestructive evaluation (NDE) and structural health monitoring (SHM) of solid composite materials, such as carbon fiber reinforced polymer (CFRP) laminates. Computational models of ultrasonic wave excitation, propagation, and scattering in CFRP composites can be extremely valuable in designing practicable NDE and SHM hardware, software, and methodologies that accomplish the desired accuracy, reliability, efficiency, and coverage. The development and application of ultrasonic simulation approaches for composite materials is an active area of research in the field of NDE. This paper presents comparisons of guided wave simulations for CFRP composites implemented using four different simulation codes: the commercial finite element modeling (FEM) packages ABAQUS, ANSYS, and COMSOL, and a custom code executing the Elastodynamic Finite Integration Technique (EFIT). Benchmark comparisons are made between the simulation tools and both experimental laser Doppler vibrometry data and theoretical dispersion curves. A pristine and a delamination type case (Teflon insert in the experimental specimen) is studied. A summary is given of the accuracy of simulation results and the respective computational performance of the four different simulation tools. Published by Elsevier B.V.

INTERLABORATORY COMPARISON OF MASS SPECTROMETRIC METHODS FOR LEAD ISOTOPES AND TRACE ELEMENTS IN NIST SRM 1400 BONE ASH

EPA Science Inventory

The results of an interlaboratory comparison are reported for he lead isotope composition and for trace element concentrations in NIST SRM 1400 Bone Ash obtained using quadrupole and magnetic-sector inductively coupled plasma mass spectrometry (ICP-MS) and (for the Pb isotopes on...

Estimation of regionalized compositions: A comparison of three methods

USGS Publications Warehouse

Pawlowsky, V.; Olea, R.A.; Davis, J.C.

1995-01-01

A regionalized composition is a random vector function whose components are positive and sum to a constant at every point of the sampling region. Consequently, the components of a regionalized composition are necessarily spatially correlated. This spatial dependence-induced by the constant sum constraint-is a spurious spatial correlation and may lead to misinterpretations of statistical analyses. Furthermore, the cross-covariance matrices of the regionalized composition are singular, as is the coefficient matrix of the cokriging system of equations. Three methods of performing estimation or prediction of a regionalized composition at unsampled points are discussed: (1) the direct approach of estimating each variable separately; (2) the basis method, which is applicable only when a random function is available that can he regarded as the size of the regionalized composition under study; (3) the logratio approach, using the additive-log-ratio transformation proposed by J. Aitchison, which allows statistical analysis of compositional data. We present a brief theoretical review of these three methods and compare them using compositional data from the Lyons West Oil Field in Kansas (USA). It is shown that, although there are no important numerical differences, the direct approach leads to invalid results, whereas the basis method and the additive-log-ratio approach are comparable. ?? 1995 International Association for Mathematical Geology.

COMPARISON OF POND AND RACEWAY PRODUCTION METHODS ON TEXTURE OF CHANNEL CATFISH (Ictalurus punctatus) FILLETS, SHOWING A DEPENDENCY ON SIZE AND FILLET POSITION

USDA-ARS?s Scientific Manuscript database

The objective of this study was to compare the effect of the production environment (pond vs in-pond raceway) on the chemical composition, color, and textural properties of channel catfish fillets. Compositional analysis consisted of percent moisture, lipid, protein, and ash content. Additional sa...

Capturing the Central Line Bundle Infection Prevention Interventions: Comparison of Reflective and Composite Modeling Methods

PubMed Central

Gilmartin, Heather M.; Sousa, Karen H.; Battaglia, Catherine

2016-01-01

Background The central line (CL) bundle interventions are important for preventing central line-associated bloodstream infections (CLABSIs), but a modeling method for testing the CL bundle interventions within a health systems framework is lacking. Objectives Guided by the Quality Health Outcomes Model (QHOM), this study tested the CL bundle interventions in reflective and composite, latent, variable measurement models to assess the impact of the modeling approaches on an investigation of the relationships between adherence to the CL bundle interventions, organizational context, and CLABSIs. Methods A secondary data analysis study was conducted using data from 614 U.S. hospitals that participated in the Prevention of Nosocomial Infection and Cost-Effectiveness-Refined study. The sample was randomly split into exploration and validation subsets. Results The two CL bundle modeling approaches resulted in adequate fitting structural models (RMSEA = .04; CFI = .94) and supported similar relationships within the QHOM. Adherence to the CL bundle had a direct effect on organizational context (reflective = .23; composite = .20; p = .01), and CLABSIs (reflective = −.28; composite = −.25; p =.01). The relationship between context and CLABSIs was not significant. Both modeling methods resulted in partial support of the QHOM. Discussion There were little statistical, but large, conceptual differences between the reflective and composite modeling approaches. The empirical impact of the modeling approaches was inconclusive, for both models resulted in a good fit to the data. Lessons learned are presented. The comparison of modeling approaches is recommended when initially modeling variables that have never been modeled, or with directional ambiguity, to increase transparency and bring confidence to study findings. PMID:27579507

An evaluation of a coupled microstructural approach for the analysis of functionally graded composites via the finite-element method

NASA Technical Reports Server (NTRS)

Pindera, Marek-Jerzy; Dunn, Patrick

1995-01-01

A comparison is presented between the predictions of the finite-element analysis and a recently developed higher-order theory for functionally graded materials subjected to a thorough-thickness temperature gradient. In contrast to existing micromechanical theories that utilize classical (i.e., uncoupled) homogenization schemes to calculate micro-level and macro-level stress and displacement fields in materials with uniform or nonuniform fiber spacing (i.e., functionally graded materials), the new theory explicitly couples the microstructural details with the macrostructure of the composite. Previous thermo-elastic analysis has demonstrated that such coupling is necessary when: the temperature gradient is large with respect to the dimension of the reinforcement; the characteristic dimension of the reinforcement is large relative to the global dimensions of the composite and the number of reinforcing fibers or inclusions is small. In these circumstances, the standard micromechanical analyses based on the concept of the representative volume element used to determine average composite properties produce questionable results. The comparison between the predictions of the finite-element method and the higher-order theory presented herein establish the theory's accuracy in predicting thermal and stress fields within composites with a finite number of fibers in the thickness direction subjected to a thorough-thickness thermal gradient.

Measured effects of surface cloth impressions on polar backscatter and comparison with a reflection grating model

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Brush, Edwin F., III; Bridal, S. L.; Holland, Mark R.; Miller, James G.

1992-01-01

This paper focuses on the nature of a typical composite surface and its effects on scattering. Utilizing epoxy typical of that in composites and standard composite fabrication methods, a sample with release cloth impressions on its surface is produced. A simple model for the scattering from the surface impressions of this sample is constructed and then polar backscatter measurements are made on the sample and compared with the model predictions.

Numerical simulation of two-dimensional heat transfer in composite bodies with application to de-icing of aircraft components. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Chao, D. F. K.

1983-01-01

Transient, numerical simulations of the de-icing of composite aircraft components by electrothermal heating were performed for a two dimensional rectangular geometry. The implicit Crank-Nicolson formulation was used to insure stability of the finite-difference heat conduction equations and the phase change in the ice layer was simulated using the Enthalpy method. The Gauss-Seidel point iterative method was used to solve the system of difference equations. Numerical solutions illustrating de-icer performance for various composite aircraft structures and environmental conditions are presented. Comparisons are made with previous studies. The simulation can also be used to solve a variety of other heat conduction problems involving composite bodies.

Optimum stacking sequence design of laminated composite circular plates with curvilinear fibres by a layer-wise optimization method

NASA Astrophysics Data System (ADS)

Guenanou, A.; Houmat, A.

2018-05-01

The optimum stacking sequence design for the maximum fundamental frequency of symmetrically laminated composite circular plates with curvilinear fibres is investigated for the first time using a layer-wise optimization method. The design variables are two fibre orientation angles per layer. The fibre paths are constructed using the method of shifted paths. The first-order shear deformation plate theory and a curved square p-element are used to calculate the objective function. The blending function method is used to model accurately the geometry of the circular plate. The equations of motion are derived using Lagrange's method. The numerical results are validated by means of a convergence test and comparison with published values for symmetrically laminated composite circular plates with rectilinear fibres. The material parameters, boundary conditions, number of layers and thickness are shown to influence the optimum solutions to different extents. The results should serve as a benchmark for optimum stacking sequences of symmetrically laminated composite circular plates with curvilinear fibres.

Evaluation of experimental methods for determining dynamic stiffness and damping of composite materials

NASA Technical Reports Server (NTRS)

Bert, C. W.; Clary, R. R.

1974-01-01

Various methods potentially usable for determining dynamic stiffness and damping of composite materials are reviewed. Of these, the following most widely used techniques are singled out for more detailed discussion: free vibration, pulse propagation, and forced vibration response. To illustrate the usefulness and validity of dynamic property data, their application in dynamic analyses and comparison with measured structural response are described for the following composite-material structures: free-free sandwich beam with glass-epoxy facings, clamped-edge sandwich plate with similar facings, free-end sandwich conical shell with similar facings, and boron-epoxy free plate with layers arranged at various orientations.

Potential Fungus surface resistance of the silica/acrylic coated leaves waste composite

NASA Astrophysics Data System (ADS)

Masturi; Jannah, WN; Maulana, RM; Darsono, T.; Sunarno; Rustad, S.

2018-04-01

The composite coated by some materials coaters have been made. This coating was done to isolate the fungus possibly growing on the composite. The composite was made from a mixture of teak leaves waste and polyurethane polymer using a simple mixing method; then the mixture was pressed at a pressure of 3 metric-tons for 15 minutes. The composite produced then was coated with acrylic only and acrylic-silica using spray method. The coated samples then were characterized using scanning electron microscopy (SEM) to determine the surface pores. Further, it was obtained the average surface pore size of acrylic coater is 1.24 µm, while the acrylic-silica pore forms an oval shape with a length and a width of 0.75 µm and 0.38 µm, respectively. In comparison with the fungus size of 2-7 µm, it can be concluded that the composite is proper as home appliance application.

Comparison of mechanical and friction properties of composite materials based on AlMg2 containing nano-dimensional particles of crystalline graphite and nanofibers of gamma oxide of aluminum

NASA Astrophysics Data System (ADS)

Aborkin, A. V.; Babin, D. M.; Soboĺkov, A. V.

2018-04-01

The method of mechanical synthesis in a planetary ball mill was used for production of composite powders based on the AlMg2 alloy containing 1 wt. % of nanosized particles of crystalline graphite or γ-Al2O3. The resulting powders are consolidated by the sintering under pressure. Using the methods of X-ray diffraction analysis, scanning and transmission electron microscopy, the structural-phase composition of bulk composite materials was studied. Comparative analysis of the microhardness, the conditional yield stress at compression, and the friction coefficient of bulk composite materials is carried out. It has been found out that the mechanical properties of composites reinforced with γ-Al2O3 nanofibers are higher than when reinforcing with nanoscale particles of crystalline graphite.

A comparison of stand structure and composition following selective-harvest at Byrne-Milliron Forest

Treesearch

Amy K. Petersen; Will Russell

2017-01-01

The effects of selective-harvest on forest composition and structure in the southern range of the coast redwood (Sequoia sempervirens (D. Don) Endl.) forest have not been well documented. This case study focused on the Byrne-Milliron Forest in Santa Cruz County, California where selective-harvest is currently the primary method of timber extraction...

Comparison of Bioelectrical Impedance and Skinfolds with Hydrodensitometry in the Assessment of Body Composition in Healthy Young Adults

ERIC Educational Resources Information Center

Rutherford, W. J.; Diemer, Gary A.; Scott, Eric D.

2011-01-01

Bioelectrical impedance analysis (BIA) is a widely used method for estimating body composition, yet issues concerning its validity persist in the literature. The purpose of this study was to validate percentage of body fat (BF) values estimated from BIA and skinfold (SF) with those obtained from hydrodensitometry (HD). Percent BF values measured…

Analytical methods to characterize heterogeneous raw material for thermal spray process: cored wire Inconel 625

NASA Astrophysics Data System (ADS)

Lindner, T.; Bonebeau, S.; Drehmann, R.; Grund, T.; Pawlowski, L.; Lampke, T.

2016-03-01

In wire arc spraying, the raw material needs to exhibit sufficient formability and ductility in order to be processed. By using an electrically conductive, metallic sheath, it is also possible to handle non-conductive and/or brittle materials such as ceramics. In comparison to massive wire, a cored wire has a heterogeneous material distribution. Due to this fact and the complex thermodynamic processes during wire arc spraying, it is very difficult to predict the resulting chemical composition in the coating with sufficient accuracy. An Inconel 625 cored wire was used to investigate this issue. In a comparative study, the analytical results of the raw material were compared to arc sprayed coatings and droplets, which were remelted in an arc furnace under argon atmosphere. Energy-dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF) analysis were used to determine the chemical composition. The phase determination was performed by X-ray diffraction (XRD). The results were related to the manufacturer specifications and evaluated in respect to differences in the chemical composition. The comparison between the feedstock powder, the remelted droplets and the thermally sprayed coatings allows to evaluate the influence of the processing methods on the resulting chemical and phase composition.

Analysis of woven fabrics for reinforced composite materials

NASA Technical Reports Server (NTRS)

Dow, Norris F.; Ramnath, V.; Rosen, B. Walter

1987-01-01

The use of woven fabrics as reinforcements for composites is considered. Methods of analysis of properties are reviewed and extended, with particular attention paid to three-dimensional constructions having through-the-thickness reinforcements. Methodology developed is used parametrically to evaluate the performance potential of a wide variety of reinforcement constructions including hybrids. Comparisons are made of predicted and measured properties of representative composites having biaxial and triaxial woven, and laminated tape lay-up reinforcements. Overall results are incorporated in advanced weave designs.

Balance Contrast Enhancement using piecewise linear stretching

NASA Astrophysics Data System (ADS)

Rahavan, R. V.; Govil, R. C.

1993-04-01

Balance Contrast Enhancement is one of the techniques employed to produce color composites with increased color contrast. It equalizes the three images used for color composition in range and mean. This results in a color composite with large variation in hue. Here, it is shown that piecewise linear stretching can be used for performing the Balance Contrast Enhancement. In comparison with the Balance Contrast Enhancement Technique using parabolic segment as transfer function (BCETP), the method presented here is algorithmically simple, constraint-free and produces comparable results.

Micromechanics-Based Progressive Failure Analysis of Composite Laminates Using Different Constituent Failure Theories

NASA Technical Reports Server (NTRS)

Moncada, Albert M.; Chattopadhyay, Aditi; Bednarcyk, Brett A.; Arnold, Steven M.

2008-01-01

Predicting failure in a composite can be done with ply level mechanisms and/or micro level mechanisms. This paper uses the Generalized Method of Cells and High-Fidelity Generalized Method of Cells micromechanics theories, coupled with classical lamination theory, as implemented within NASA's Micromechanics Analysis Code with Generalized Method of Cells. The code is able to implement different failure theories on the level of both the fiber and the matrix constituents within a laminate. A comparison is made among maximum stress, maximum strain, Tsai-Hill, and Tsai-Wu failure theories. To verify the failure theories the Worldwide Failure Exercise (WWFE) experiments have been used. The WWFE is a comprehensive study that covers a wide range of polymer matrix composite laminates. The numerical results indicate good correlation with the experimental results for most of the composite layups, but also point to the need for more accurate resin damage progression models.

Comparing and improving reconstruction methods for proxies based on compositional data

NASA Astrophysics Data System (ADS)

Nolan, C.; Tipton, J.; Booth, R.; Jackson, S. T.; Hooten, M.

2017-12-01

Many types of studies in paleoclimatology and paleoecology involve compositional data. Often, these studies aim to use compositional data to reconstruct an environmental variable of interest; the reconstruction is usually done via the development of a transfer function. Transfer functions have been developed using many different methods. Existing methods tend to relate the compositional data and the reconstruction target in very simple ways. Additionally, the results from different methods are rarely compared. Here we seek to address these two issues. First, we introduce a new hierarchical Bayesian multivariate gaussian process model; this model allows for the relationship between each species in the compositional dataset and the environmental variable to be modeled in a way that captures the underlying complexities. Then, we compare this new method to machine learning techniques and commonly used existing methods. The comparisons are based on reconstructing the water table depth history of Caribou Bog (an ombrotrophic Sphagnum peat bog in Old Town, Maine, USA) from a new 7500 year long record of testate amoebae assemblages. The resulting reconstructions from different methods diverge in both their resulting means and uncertainties. In particular, uncertainty tends to be drastically underestimated by some common methods. These results will help to improve inference of water table depth from testate amoebae. Furthermore, this approach can be applied to test and improve inferences of past environmental conditions from a broad array of paleo-proxies based on compositional data

Nanodiamond embedded ta-C composite film by pulsed filtered vacuum arc deposition from a single target

NASA Astrophysics Data System (ADS)

Iyer, Ajai; Etula, Jarkko; Ge, Yanling; Liu, Xuwen; Koskinen, Jari

2016-11-01

Detonation Nanodiamonds (DNDs) are known to have sp3 core, sp2 shell, small size (few nm) and are gaining importance as multi-functional nanoparticles. Diverse methods have been used to form composites, containing detonation nanodiamonds (DNDs) embedded in conductive and dielectric matrices for various applications. Here we show a method, wherein DND-ta-C composite film, consisting of DNDs embedded in ta-C matrix have been co-deposited from the same cathode by pulsed filtered cathodic vacuum arc method. Transmission Electron Microscope analysis of these films revel the presence of DNDs embedded in the matrix of amorphous carbon. Raman spectroscopy indicates that the presence of DNDs does not adversely affect the sp3 content of DND-ta-C composite film compared to ta-C film of same thickness. Nanoindentation and nanowear tests indicate that DND-ta-C composite films possess improved mechanical properties in comparison to ta-C films of similar thickness.

Comparison of four glycosyl residue composition methods for effectiveness in detecting sugars from cell walls of dicot and grass tissues.

PubMed

Biswal, Ajaya K; Tan, Li; Atmodjo, Melani A; DeMartini, Jaclyn; Gelineo-Albersheim, Ivana; Hunt, Kimberly; Black, Ian M; Mohanty, Sushree S; Ryno, David; Wyman, Charles E; Mohnen, Debra

2017-01-01

The effective use of plant biomass for biofuel and bioproduct production requires a comprehensive glycosyl residue composition analysis to understand the different cell wall polysaccharides present in the different biomass sources. Here we compared four methods side-by-side for their ability to measure the neutral and acidic sugar composition of cell walls from herbaceous, grass, and woody model plants and bioenergy feedstocks. Arabidopsis, Populus , rice, and switchgrass leaf cell walls, as well as cell walls from Populus wood, rice stems, and switchgrass tillers, were analyzed by (1) gas chromatography-mass spectrometry (GC-MS) of alditol acetates combined with a total uronic acid assay; (2) carbodiimide reduction of uronic acids followed by GC-MS of alditol acetates; (3) GC-MS of trimethylsilyl (TMS) derivatives; and (4) high-pressure, anion-exchange chromatography (HPAEC). All four methods gave comparable abundance ranking of the seven neutral sugars, and three of the methods were able to quantify unique acidic sugars. The TMS, HPAEC, and carbodiimide methods provided comparable quantitative results for the specific neutral and acidic sugar content of the biomass, with the TMS method providing slightly greater yield of specific acidic sugars and high total sugar yields. The alditol acetate method, while providing comparable information on the major neutral sugars, did not provide the requisite quantitative information on the specific acidic sugars in plant biomass. Thus, the alditol acetate method is the least informative of the four methods. This work provides a side-by-side comparison of the efficacy of four different established glycosyl residue composition analysis methods in the analysis of the glycosyl residue composition of cell walls from both dicot (Arabidopsis and Populus ) and grass (rice and switchgrass) species. Both primary wall-enriched leaf tissues and secondary wall-enriched wood/stem tissues were analyzed for mol% and mass yield of the non-cellulosic sugars. The TMS, HPAEC, and carbodiimide methods were shown to provide comparable quantitative data on the nine neutral and acidic sugars present in all plant cell walls.

Tags, wireless communication systems, tag communication methods, and wireless communications methods

DOEpatents

Scott,; Jeff W. , Pratt; Richard, M [Richland, WA

2006-09-12

Tags, wireless communication systems, tag communication methods, and wireless communications methods are described. In one aspect, a tag includes a plurality of antennas configured to receive a plurality of first wireless communication signals comprising data from a reader, a plurality of rectifying circuits coupled with. respective individual ones of the antennas and configured to provide rectified signals corresponding to the first wireless communication signals, wherein the rectified signals are combined to produce a composite signal, an adaptive reference circuit configured to vary a reference signal responsive to the composite signal, a comparator coupled with the adaptive reference circuit and the rectifying circuits and configured to compare the composite signal with respect to the reference signal and to output the data responsive to the comparison, and processing circuitry configured to receive the data from the comparator and to process the data.

An Applied Method for Predicting the Load-Carrying Capacity in Compression of Thin-Wall Composite Structures with Impact Damage

NASA Astrophysics Data System (ADS)

Mitrofanov, O.; Pavelko, I.; Varickis, S.; Vagele, A.

2018-03-01

The necessity for considering both strength criteria and postbuckling effects in calculating the load-carrying capacity in compression of thin-wall composite structures with impact damage is substantiated. An original applied method ensuring solution of these problems with an accuracy sufficient for practical design tasks is developed. The main advantage of the method is its applicability in terms of computing resources and the set of initial data required. The results of application of the method to solution of the problem of compression of fragments of thin-wall honeycomb panel damaged by impacts of various energies are presented. After a comparison of calculation results with experimental data, a working algorithm for calculating the reduction in the load-carrying capacity of a composite object with impact damage is adopted.

Probabilistic Composite Design

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

1997-01-01

Probabilistic composite design is described in terms of a computational simulation. This simulation tracks probabilistically the composite design evolution from constituent materials, fabrication process, through composite mechanics and structural components. Comparisons with experimental data are provided to illustrate selection of probabilistic design allowables, test methods/specimen guidelines, and identification of in situ versus pristine strength, For example, results show that: in situ fiber tensile strength is 90% of its pristine strength; flat-wise long-tapered specimens are most suitable for setting ply tensile strength allowables: a composite radome can be designed with a reliability of 0.999999; and laminate fatigue exhibits wide-spread scatter at 90% cyclic-stress to static-strength ratios.

Estimation of pyrethroid pesticide intake using regression ...

EPA Pesticide Factsheets

Population-based estimates of pesticide intake are needed to characterize exposure for particular demographic groups based on their dietary behaviors. Regression modeling performed on measurements of selected pesticides in composited duplicate diet samples allowed (1) estimation of pesticide intakes for a defined demographic community, and (2) comparison of dietary pesticide intakes between the composite and individual samples. Extant databases were useful for assigning individual samples to composites, but they could not provide the breadth of information needed to facilitate measurable levels in every composite. Composite sample measurements were found to be good predictors of pyrethroid pesticide levels in their individual sample constituents where sufficient measurements are available above the method detection limit. Statistical inference shows little evidence of differences between individual and composite measurements and suggests that regression modeling of food groups based on composite dietary samples may provide an effective tool for estimating dietary pesticide intake for a defined population. The research presented in the journal article will improve community's ability to determine exposures through the dietary route with a less burdensome and costly method.

Interlaboratory Comparison of Methods Determining the Botanical Composition of Animal Feed.

PubMed

Braglia, Luca; Morello, Laura; Gavazzi, Floriana; Gianì, Silvia; Mastromauro, Francesco; Breviario, Diego; Cardoso, Hélia Guerra; Valadas, Vera; Campos, Maria Doroteia

2018-01-01

A consortium of European enterprises and research institutions has been engaged in the Feed-Code Project with the aim of addressing the requirements stated in European Union Regulation No. 767/2009, concerning market placement and use of feed of known and ascertained botanical composition. Accordingly, an interlaboratory trial was set up to compare the performance of different assays based either on optical microscope or DNA analysis for the qualitative and quantitative identification of the composition of compound animal feeds. A tubulin-based polymorphism method, on which the Feed-Code platform was developed, provided the most accurate results. The present study highlights the need for the performance of ring trials for the determination of the botanical composition of animal feeds and raises an alarm on the actual status of analytical inaccuracy.

Design for inadvertent damage in composite laminates

NASA Technical Reports Server (NTRS)

Singhal, Surendra N.; Chamis, Christos C.

1992-01-01

Simplified predictive methods and models to computationally simulate durability and damage in polymer matrix composite materials/structures are described. The models include (1) progressive fracture, (2) progressively damaged structural behavior, (3) progressive fracture in aggressive environments, (4) stress concentrations, and (5) impact resistance. Several examples are included to illustrate applications of the models and to identify significant parameters and sensitivities. Comparisons with limited experimental data are made.

A Comparison of Segregation Indices Used for Assessing the Socio-Economic Composition of Schools. Measuring Markets: The Case of the ERA 1988. Working Paper.

ERIC Educational Resources Information Center

Gorard, Stephen; Taylor, Chris

This paper examines the changing socioeconomic composition of English and Welsh schools over 11 years following the Education Reform Act of 1988, using many indicators of socioeconomic disadvantage and methods of measuring the changing spread of disadvantage among schools (segregation). It explains how to assess segregation (percentage differences…

A comparison of the wear resistance and hardness of indirect composite resins.

PubMed

Mandikos, M N; McGivney, G P; Davis, E; Bush, P J; Carter, J M

2001-04-01

Various new, second-generation indirect composites have been developed with claimed advantages over existing tooth-colored restorative materials. To date, little independent research has been published on these materials, and the properties specified in the advertising materials are largely derived from in-house or contracted testing. Four second-generation indirect composites (Artglass, belleGlass, Sculpture, and Targis) were tested for wear resistance and hardness against 2 control materials with well-documented clinical application. Human enamel was also tested for comparison. Twelve specimens of each material were fabricated according to the manufacturers' directions and subjected to accelerated wear in a 3-body abrasion, toothbrushing apparatus. Vickers hardness was measured for each of the tested materials, and energy dispersive x-ray (EDX) spectroscopy was performed to determine the elemental composition of the composite fillers. The statistical tests used for wear and hardness were the Kruskal-Wallis 1-way ANOVA test with Mann-Whitney tests and 1-way ANOVA with multiple comparisons (Tukey HSD). The Pearson correlation coefficient was used to determine the existence of a relationship between the hardness of the materials and the degree to which they had worn. The level of statistical significance chosen was alpha=.05. The control material Concept was superior to the other composites in wear resistance and hardness and had the lowest surface roughness. Significant relationships were observed between depth of wear and hardness and between depth of wear and average surface roughness. Enamel specimens were harder and more wear resistant than any of the composites. EDX spectroscopy revealed that the elemental composition of the fillers of the 4 new composites was almost identical, as was the composition of the 2 control composites. The differences in wear, hardness, and average surface roughness may have been due to differences in the chemistry or method of polymerization of the composites. Further research in this area should be encouraged. It was also apparent that the filler present in the tested composites did not exactly fit the manufacturers' descriptions.

Capturing the Central Line Bundle Infection Prevention Interventions: Comparison of Reflective and Composite Modeling Methods.

PubMed

Gilmartin, Heather M; Sousa, Karen H; Battaglia, Catherine

2016-01-01

The central line (CL) bundle interventions are important for preventing central line-associated bloodstream infections (CLABSIs), but a modeling method for testing the CL bundle interventions within a health systems framework is lacking. Guided by the Quality Health Outcomes Model (QHOM), this study tested the CL bundle interventions in reflective and composite, latent, variable measurement models to assess the impact of the modeling approaches on an investigation of the relationships between adherence to the CL bundle interventions, organizational context, and CLABSIs. A secondary data analysis study was conducted using data from 614 U.S. hospitals that participated in the Prevention of Nosocomial Infection and Cost-Effectiveness Refined study. The sample was randomly split into exploration and validation subsets. The two CL bundle modeling approaches resulted in adequate fitting structural models (RMSEA = .04; CFI = .94) and supported similar relationships within the QHOM. Adherence to the CL bundle had a direct effect on organizational context (reflective = .23; composite = .20; p = .01) and CLABSIs (reflective = -.28; composite = -.25; p = .01). The relationship between context and CLABSIs was not significant. Both modeling methods resulted in partial support of the QHOM. There were little statistical, but large, conceptual differences between the reflective and composite modeling approaches. The empirical impact of the modeling approaches was inconclusive, for both models resulted in a good fit to the data. Lessons learned are presented. The comparison of modeling approaches is recommended when initially modeling variables that have never been modeled or with directional ambiguity to increase transparency and bring confidence to study findings.

A unified in vitro evaluation for apatite-forming ability of bioactive glasses and their variants.

PubMed

Maçon, Anthony L B; Kim, Taek B; Valliant, Esther M; Goetschius, Kathryn; Brow, Richard K; Day, Delbert E; Hoppe, Alexander; Boccaccini, Aldo R; Kim, Ill Yong; Ohtsuki, Chikara; Kokubo, Tadashi; Osaka, Akiyoshi; Vallet-Regí, Maria; Arcos, Daniel; Fraile, Leandro; Salinas, Antonio J; Teixeira, Alexandra V; Vueva, Yuliya; Almeida, Rui M; Miola, Marta; Vitale-Brovarone, Chiara; Verné, Enrica; Höland, Wolfram; Jones, Julian R

2015-02-01

The aim of this study was to propose and validate a new unified method for testing dissolution rates of bioactive glasses and their variants, and the formation of calcium phosphate layer formation on their surface, which is an indicator of bioactivity. At present, comparison in the literature is difficult as many groups use different testing protocols. An ISO standard covers the use of simulated body fluid on standard shape materials but it does not take into account that bioactive glasses can have very different specific surface areas, as for glass powders. Validation of the proposed modified test was through round robin testing and comparison to the ISO standard where appropriate. The proposed test uses fixed mass per solution volume ratio and agitated solution. The round robin study showed differences in hydroxyapatite nucleation on glasses of different composition and between glasses of the same composition but different particle size. The results were reproducible between research facilities. Researchers should use this method when testing new glasses, or their variants, to enable comparison between the literature in the future.

Automated compromised right lung segmentation method using a robust atlas-based active volume model with sparse shape composition prior in CT.

PubMed

Zhou, Jinghao; Yan, Zhennan; Lasio, Giovanni; Huang, Junzhou; Zhang, Baoshe; Sharma, Navesh; Prado, Karl; D'Souza, Warren

2015-12-01

To resolve challenges in image segmentation in oncologic patients with severely compromised lung, we propose an automated right lung segmentation framework that uses a robust, atlas-based active volume model with a sparse shape composition prior. The robust atlas is achieved by combining the atlas with the output of sparse shape composition. Thoracic computed tomography images (n=38) from patients with lung tumors were collected. The right lung in each scan was manually segmented to build a reference training dataset against which the performance of the automated segmentation method was assessed. The quantitative results of this proposed segmentation method with sparse shape composition achieved mean Dice similarity coefficient (DSC) of (0.72, 0.81) with 95% CI, mean accuracy (ACC) of (0.97, 0.98) with 95% CI, and mean relative error (RE) of (0.46, 0.74) with 95% CI. Both qualitative and quantitative comparisons suggest that this proposed method can achieve better segmentation accuracy with less variance than other atlas-based segmentation methods in the compromised lung segmentation. Published by Elsevier Ltd.

Comparison of time-dependent changes in the surface hardness of different composite resins

PubMed Central

Ozcan, Suat; Yikilgan, Ihsan; Uctasli, Mine Betul; Bala, Oya; Kurklu, Zeliha Gonca Bek

2013-01-01

Objective: The aim of this study was to evaluate the change in surface hardness of silorane-based composite resin (Filtek Silorane) in time and compare the results with the surface hardness of two methacrylate-based resins (Filtek Supreme and Majesty Posterior). Materials and Methods: From each composite material, 18 wheel-shaped samples (5-mm diameter and 2-mm depth) were prepared. Top and bottom surface hardness of these samples was measured using a Vicker's hardness tester. The samples were then stored at 37°C and 100% humidity. After 24 h and 7, 30 and 90 days, the top and bottom surface hardness of the samples was measured. In each measurement, the rate between the hardness of the top and bottom surfaces were recorded as the hardness rate. Statistical analysis was performed by one-way analysis of variance, multiple comparisons by Tukey's test and binary comparisons by t-test with a significance level of P = 0.05. Results: The highest hardness values were obtained from each two surfaces of Majesty Posterior and the lowest from Filtek Silorane. Both the top and bottom surface hardness of the methacrylate based composite resins was high and there was a statistically significant difference between the top and bottom hardness values of only the silorane-based composite, Filtek Silorane (P < 0.05). The lowest was obtained with Filtek Silorane. The hardness values of all test groups increased after 24 h (P < 0.05). Conclusion: Although silorane-based composite resin Filtek Silorane showed adequate hardness ratio, the use of incremental technic during application is more important than methacrylate based composites. PMID:24966724

Chemical composition and antibacterial activity of selected essential oils and some of their main compounds.

PubMed

Wanner, Juergen; Schmidt, Erich; Bail, Stefanie; Jirovetz, Leopold; Buchbauer, Gerhard; Gochev, Velizar; Girova, Tanya; Atanasova, Teodora; Stoyanova, Albena

2010-09-01

The chemical composition of essential oils of cabreuva (Myrocarpus fastigiatus Allemao, Fabaceae) from Brazil, cedarwood (Juniperus ashei, Cupressaceae) from Texas, Juniper berries (Juniperus communis L., Cupressaceae) and myrrh (Commiphora myrrha (Nees) Engl., Burseraceae) were analyzed using GC/FID and GC/MS. The antimicrobial activity of these essential oils and some of their main compounds were tested against eleven different strains of Gram-positive and Gram-negative bacteria by using agar diffusion and agar serial dilution methods. Animal and plant pathogens, food poisoning and spoilage bacteria were selected. The volatile oils exhibited considerable inhibitory effects against all tested organisms, except Pseudomonas, using both test methods. Higher activity was observed against Gram-positive strains in comparison with Gram-negative bacteria. Cabreuva oil from Brazil showed similar results, but in comparison with the other oils tested, only when higher concentrations of oil were used.

A comparison of simple shear characterization methods for composite laminates

NASA Technical Reports Server (NTRS)

Yeow, Y. T.; Brinson, H. F.

1978-01-01

Various methods for the shear stress/strain characterization of composite laminates are examined and their advantages and limitations are briefly discussed. Experimental results and the necessary accompanying analysis are then presented and compared for three simple shear characterization procedures. These are the off-axis tensile test method, the (+/- 45 deg)s tensile test method and the (0/90 deg)s symmetric rail shear test method. It is shown that the first technique indicates the shear properties of the graphite/epoxy laminates investigated are fundamentally brittle in nature while the latter two methods tend to indicate that these laminates are fundamentally ductile in nature. Finally, predictions of incrementally determined tensile stress/strain curves utilizing the various different shear behaviour methods as input information are presented and discussed.

A comparison of simple shear characterization methods for composite laminates

NASA Technical Reports Server (NTRS)

Yeow, Y. T.; Brinson, H. F.

1977-01-01

Various methods for the shear stress-strain characterization of composite laminates are examined, and their advantages and limitations are briefly discussed. Experimental results and the necessary accompanying analysis are then presented and compared for three simple shear characterization procedures. These are the off-axis tensile test method, the + or - 45 degs tensile test method and the 0 deg/90 degs symmetric rail shear test method. It is shown that the first technique indicates that the shear properties of the G/E laminates investigated are fundamentally brittle in nature while the latter two methods tend to indicate that the G/E laminates are fundamentally ductile in nature. Finally, predictions of incrementally determined tensile stress-strain curves utilizing the various different shear behavior methods as input information are presented and discussed.

Formation of protective composite coatings with the use of solution of TFE telomers

NASA Astrophysics Data System (ADS)

Mashtalyar, D. V.; Gnedenkov, S. V.; Sinebryukhov, S. L.; Nadaraia, K. V.; Kiryukhin, D. P.; Kushch, P. P.; Kichigina, G. A.; Buznik, V. M.

2017-09-01

This paper presents the method of fabricate and the results of investigation of electrochemical properties and wettability of the composite coatings obtained on the magnesium alloy by plasma electrolytic oxidation (PEO) and the use of the solution of tetrafluoroethylene (TFE) telomers. The fluoropolymer-containing coatings decrease corrosion current density, increase contact angle in comparison with the base PEO-coating and the bare alloy.

Comparison of Requirements for Composite Structures for Aircraft and Space Applications

NASA Technical Reports Server (NTRS)

Raju, Ivatury S.; Elliott, Kenny B.; Hampton, Roy W.; Knight, Norman F., Jr.; Aggarwal, Pravin; Engelstad, Stephen P.; Chang, James B.

2010-01-01

In this paper, the aircraft and space vehicle requirements for composite structures are compared. It is a valuable exercise to study composite structural design approaches used in the airframe industry, and to adopt methodology that is applicable for space vehicles. The missions, environments, analysis methods, analysis validation approaches, testing programs, build quantities, inspection, and maintenance procedures used by the airframe industry, in general, are not transferable to spaceflight hardware. Therefore, while the application of composite design approaches from other industries is appealing, many aspects cannot be directly utilized. Nevertheless, experiences and research for composite aircraft structures may be of use in unexpected arenas as space exploration technology develops, and so continued technology exchanges are encouraged.

Fracture and fatigue of discontinuously reinforced copper/tungsten composites

NASA Technical Reports Server (NTRS)

Harris, B.; Ramani, S. V.

1975-01-01

The strength, toughness and resistance to cyclic crack propagation of composites consisting of copper reinforced with short tungsten wires of various lengths have been studied and the results compared with the behavior of continuously reinforced composites manufactured by the same method, i.e., by vacuum hot-pressing. It has been found that whereas the resistance to fatigue crack growth of continuously reinforced composites is very similar to that of continuous Al/stainless steel composites reported elsewhere, the addition of short fibers completely changes the mode of fracture, and no direct comparisons are possible. In effect, short fibers inhibit single crack growth by causing plastic flow to be distributed rather than localized, and although these composites are much less strong than continuous fiber composites, they nevertheless have much greater fatigue resistance.

Field comparison of body composition techniques: hydrostatic weighing, skinfold thickness, and bioelectric impedance.

PubMed

Kirkendall, D T; Grogan, J W; Bowers, R G

1991-01-01

Body composition and appropriate playing weight are frequently requested by coaches. Numerous methods for estimating these figures are available, and each has its own limitation, be it technical or biological. A comparison of three common methods was made-underwater weighting (H2O, the criterion), skinfold thicknesses (SF), and commercial bioelectrical impedance analysis (BIA). Subjects were 29 professional football players measured by each of the three methods after an overnight fast. Data was collected 10 weeks preceding the players' formal training camp. There was no difference for percentage of weight as fat between SF (15.8%) and H2O (14.2%). Bioelectrical impedance analysis significantly (p < .05) overestimated percent fat (19.2%) compared to H20. Error rates when regressing SF on H2O were favorable, whether expressed for the whole sample (3.04%) or by race (1.78% or 3.56% for whites and blacks, respectively). Regression of BIA on H2O showed an elevated, overall error rate (14.12%) and elevated error rates for whites (11.57%) and blacks (13.81%). Of the two estimates of body composition on a racially mixed sample of males, SF provided the best estimate with the least amount of error. J Orthop Sports Phys Ther 1991;13(5):235-239.

A comparison of analysis tools for predicting the inelastic cyclic response of cross-ply titanium matrix composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kroupa, J.L.; Coker, D.; Neu, R.W.

1996-12-31

Several micromechanical models that are currently being used for predicting the thermal and mechanical behavior of a cross-ply, [0/90], titanium matrix composite are evaluated. Six computer programs or methods are compared: (1) VISCOPLY; (2) METCAN; (3) FIDEP, an enhanced concentric cylinder model; (4) LISOL, a modified method of cells approach; (5) an elementary approach where the [90] ply is assumed to have the same properties as the matrix; and (6) a finite element method. Comparisons are made for the thermal residual stresses at room temperature resulting from processing, as well as for stresses and strains in two isothermal and twomore » thermomechanical fatigue test cases. For each case, the laminate response of the models is compared to experimental behavior, while the responses of the constituents are compared among the models. The capability of each model to predict frequency effects, inelastic cyclic strain (hysteresis) behavior, and strain ratchetting with cycling is shown. The basis of formulation for the micromechanical models, the constitutive relationships used for the matrix and fiber, and the modeling technique of the [90] ply are all found to be important factors for determining the accurate behavior of the [0/90] composite.« less

COMPARISON OF USEPA FIELD SAMPLING METHODS FOR BENTHIC MACROINVERTEBRATE STUDIES

EPA Science Inventory

Two U.S. Environmental Protection Agency (USEPA) macroinvertebrate sampling protocols were compared in the Mid-Atlantic Highlands region. The Environmental Monitoring and Assessment Program (EMAP) wadeable streams protocol results in a single composite sample from nine transects...

KEY COMPARISON: Final report on CCQM-K57: Chemical composition of clay

NASA Astrophysics Data System (ADS)

Salas, Antonio; Ramírez, Estele

2009-01-01

After the successful completion of the pilot study, CCQM-P65 [1], the Inorganic Analysis Working Group of CCQM agreed to conduct key comparison CCQM-K57, Chemical composition of clay, in Paris, April 2006. The natural mass fraction levels of five elements—Si, Ca, Fe, Al and Mg—were measured and reported as oxides in clay. Six national metrology institutes participated in CCQM K57, and CENAM (Querétaro, Mexico) coordinated. The methods employed were isotope dilution mass spectrometry (IDMS), inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-optical emission spectrometry (ICP-OES) using the dehydration method and condensation method, gravimetric analysis, neutron activation analysis (NAA), prompt gamma activation analysis (PGAA) and x-ray fluorescence spectrometry (XRF) with the reconstitution method and external calibration. This final report presents the capability of the participant institutes, based on the KCRV, which was approved at the IAWG spring meeting in 2008, and the equivalence statements regarding the KCRV, approved at its autumn meeting. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Comparison of composite rotor blade models: A coupled-beam analysis and an MSC/NASTRAN finite-element model

NASA Technical Reports Server (NTRS)

Hodges, Robert V.; Nixon, Mark W.; Rehfield, Lawrence W.

1987-01-01

A methodology was developed for the structural analysis of composite rotor blades. This coupled-beam analysis is relatively simple to use compared with alternative analysis techniques. The beam analysis was developed for thin-wall single-cell rotor structures and includes the effects of elastic coupling. This paper demonstrates the effectiveness of the new composite-beam analysis method through comparison of its results with those of an established baseline analysis technique. The baseline analysis is an MSC/NASTRAN finite-element model built up from anisotropic shell elements. Deformations are compared for three linear static load cases of centrifugal force at design rotor speed, applied torque, and lift for an ideal rotor in hover. A D-spar designed to twist under axial loading is the subject of the analysis. Results indicate the coupled-beam analysis is well within engineering accuracy.

Effect of temperature on optical properties of PMMA/SiO2 composite thin film

NASA Astrophysics Data System (ADS)

Soni, Gyanesh; Srivastava, Subodh; Soni, Purushottam; Kalotra, Pankaj; Vijay, Y. K.

2018-05-01

Effect of temperature on PMMA/SiO2 composites thin films were investigated. Nanocomposite flexible thin films of 60 µm thicknesses with different loading of SiO2 nanoparticles were prepared using solution casting method. SEM images show that SiO2 nanoparticles are distributed uniformly in PMMA matrix without any lumps on the surface, and PMMA/SiO2 nano composite thin films had a smoother and regular morphology. UV-Vis and optical band gap measurements revealed that both the concentration of SiO2 nanoparticles and temperature affect the optical properties of the composite thin film in comparison to the pure PMMA film.

Determining absolute protein numbers by quantitative fluorescence microscopy.

PubMed

Verdaasdonk, Jolien Suzanne; Lawrimore, Josh; Bloom, Kerry

2014-01-01

Biological questions are increasingly being addressed using a wide range of quantitative analytical tools to examine protein complex composition. Knowledge of the absolute number of proteins present provides insights into organization, function, and maintenance and is used in mathematical modeling of complex cellular dynamics. In this chapter, we outline and describe three microscopy-based methods for determining absolute protein numbers--fluorescence correlation spectroscopy, stepwise photobleaching, and ratiometric comparison of fluorescence intensity to known standards. In addition, we discuss the various fluorescently labeled proteins that have been used as standards for both stepwise photobleaching and ratiometric comparison analysis. A detailed procedure for determining absolute protein number by ratiometric comparison is outlined in the second half of this chapter. Counting proteins by quantitative microscopy is a relatively simple yet very powerful analytical tool that will increase our understanding of protein complex composition. © 2014 Elsevier Inc. All rights reserved.

Prediction of progressive damage and strength of plain weave composites using the finite element method

NASA Astrophysics Data System (ADS)

Srirengan, Kanthikannan

The overall objective of this research was to develop the finite element code required to efficiently predict the strength of plain weave composite structures. Towards which, three-dimensional conventional progressive damage analysis was implemented to predict the strength of plain weave composites subjected to periodic boundary conditions. Also, modal technique for three-dimensional global/local stress analysis was developed to predict the failure initiation in plain weave composite structures. The progressive damage analysis was used to study the effect of quadrature order, mesh refinement and degradation models on the predicted damage and strength of plain weave composites subjected to uniaxial tension in the warp tow direction. A 1/32sp{nd} part of the representative volume element of a symmetrically stacked configuration was analyzed. The tow geometry was assumed to be sinusoidal. Graphite/Epoxy system was used. Maximum stress criteria and combined stress criteria were used to predict failure in the tows and maximum principal stress criterion was used to predict failure in the matrix. Degradation models based on logical reasoning, micromechanics idealization and experimental comparisons were used to calculate the effective material properties with of damage. Modified Newton-Raphson method was used to determine the incremental solution for each applied strain level. Using a refined mesh and the discount method based on experimental comparisons, the progressive damage and the strength of plain weave composites of waviness ratios 1/3 and 1/6 subjected to uniaxial tension in the warp direction have been characterized. Plain weave composites exhibit a brittle response in uniaxial tension. The strength decreases significantly with the increase in waviness ratio. Damage initiation and collapse were caused dominantly due to intra-tow cracking and inter-tow debonding respectively. The predicted strength of plain weave composites of racetrack geometry and waviness ratio 1/25.7 was compared with analytical predictions and experimental findings and was found to match well. To evaluate the performance of the modal technique, failure initiation in a short woven composite cantilevered plate subjected to end moment and transverse end load was predicted. The global/local predictions were found to reasonably match well with the conventional finite element predictions.

Influence of surface rectangular defect winding layer on burst pressure of CNG-II composite cylinder

NASA Astrophysics Data System (ADS)

You, H. X.; Peng, L.; Zhao, C.; Ma, K.; Zhang, S.

2018-01-01

To study the influence of composite materials’ surface defect on the burst pressure of CNG-II composite cylinder, the surface defect was simplified as a rectangular slot of certain size on the basis of actually investigating the shape of cylinder’s surface defect. A CNG-II composite cylinder with a rectangular slot defect (2mm in depth) was used for burst test, and the numerical simulation software ANSYS was used to calculate its burst pressure. Through comparison between the burst pressure in the test and the numerical analysis result, the correctness of the numerical analysis method was verified. On this basis, the numerical analysis method was conducted for composite cylinders with surface defect in other depth. The result showed that surface defect in the form of rectangular slot had no significant effect on the liner stress of composite cylinder. Instead, it had a great influence on the stress of fiber-wrapped layer. The burst pressure of the composite cylinder decreased as the defect depth increasing. The hoop stress at the bottom of the defect in the shape of rectangular slot exceeded the maximum of the composite materials’ tensile strength, which could result in the burst pressure of composite cylinders decreasing.

Composition Studies with the Telescope Array Surface Detector

NASA Astrophysics Data System (ADS)

Kuznetsov, Mikhail; Piskunov, Maxim; Rubtsov, Grigory; Troitsky, Sergey; Zhezher, Yana

The results on ultra-high-energy cosmic-ray chemical composition based on the data from the Telescope Array surface-detector are presented. The method is based on the multivariate boosted decision tree (BDT) analysis which uses surface-detector observables. The results on average atomic mass in the energy range 1018.0-1020.0 eV are presented. A comparison with the Telescope Array hybrid results and the Pierre Auger Observatory surface detector results is shown.

Assessment of repeatability of composition of perfumed waters by high-performance liquid chromatography combined with numerical data analysis based on cluster analysis (HPLC UV/VIS - CA).

PubMed

Ruzik, L; Obarski, N; Papierz, A; Mojski, M

2015-06-01

High-performance liquid chromatography (HPLC) with UV/VIS spectrophotometric detection combined with the chemometric method of cluster analysis (CA) was used for the assessment of repeatability of composition of nine types of perfumed waters. In addition, the chromatographic method of separating components of the perfume waters under analysis was subjected to an optimization procedure. The chromatograms thus obtained were used as sources of data for the chemometric method of cluster analysis (CA). The result was a classification of a set comprising 39 perfumed water samples with a similar composition at a specified level of probability (level of agglomeration). A comparison of the classification with the manufacturer's declarations reveals a good degree of consistency and demonstrates similarity between samples in different classes. A combination of the chromatographic method with cluster analysis (HPLC UV/VIS - CA) makes it possible to quickly assess the repeatability of composition of perfumed waters at selected levels of probability. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Heat of combustion of tantalum-tungsten oxide thermite composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cervantes, Octavio G.; Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616; Kuntz, Joshua D.

2010-12-15

The heat of combustion of two distinctly synthesized stoichiometric tantalum-tungsten oxide energetic composites was investigated by bomb calorimetry. One composite was synthesized using a sol-gel (SG) derived method in which micrometric-scale tantalum is immobilized in a tungsten oxide three-dimensional nanostructured network structure. The second energetic composite was made from the mixing of micrometric-scale tantalum and commercially available (CA) nanometric tungsten oxide powders. The energetic composites were consolidated using the spark plasma sintering (SPS) technique under a 300 MPa pressure and at temperatures of 25, 400, and 500 C. For samples consolidated at 25 C, the density of the CA compositemore » is 61.65 {+-} 1.07% in comparison to 56.41 {+-} 1.19% for the SG derived composite. In contrast, the resulting densities of the SG composite are higher than the CA composite for samples consolidated at 400 and 500 C. The theoretical maximum density for the SG composite consolidated to 400 and 500 C are 81.30 {+-} 0.58% and 84.42 {+-} 0.62%, respectively. The theoretical maximum density of the CA composite consolidated to 400 and 500 C are 74.54 {+-} 0.80% and 77.90 {+-} 0.79%, respectively. X-ray diffraction analyses showed an increase of pre-reaction of the constituents with an increase in the consolidation temperature. The increase in pre-reaction results in lower stored energy content for samples consolidated to 400 and 500 C in comparison to samples consolidated at 25 C. (author)« less

Comparison of Multifrequency Bioelectrical Impedance vs. Dual-Energy X-ray Absorptiometry for Assessing Body Composition Changes After Participation in a 10-Week Resistance Training Program.

PubMed

Schoenfeld, Brad J; Nickerson, Brett S; Wilborn, Colin D; Urbina, Stacie L; Hayward, Sara B; Krieger, James; Aragon, Alan A; Tinsley, Grant M

2018-06-20

Schoenfeld, BJ, Nickerson, BS, Wilborn, CD, Urbina, SL, Hayward, SB, Krieger, J, Aragon, AA, and Tinsley, G. Comparison of multifrequency bioelectrical impedance vs. dual-energy x-ray absorptiometry for assessing body composition changes after participation in a 10-week resistance training program. J Strength Cond Res XX(X): 000-000, 2018-The purpose of this study was to assess the ability of multifrequency bioelectrical impedance analysis (MF-BIA) to determine alterations in total and segmental body composition across a 10-week resistance training (RT) program in comparison with the criterion reference dual-energy X-ray absorptiometry (DXA). Twenty-one young male volunteers (mean ± SD; age = 22.9 ± 3.0 years; height = 175.5 ± 5.9 cm; body mass = 82.9 ± 13.6 kg; body mass index = 26.9 ± 3.6) performed an RT program that included exercises for all major muscle groups. Body composition was assessed using both methods before and after the intervention; change scores were determined by subtracting pre-test values from post-test values for percent body fat ([INCREMENT]%BF), fat mass ([INCREMENT]FM), and fat-free mass ([INCREMENT]FFM). Mean changes were not significantly different when comparing MF-BIA with DXA for [INCREMENT]%BF (-1.05 vs. -1.28%), [INCREMENT]FM (-1.13 vs. -1.19 kg), and FFM (0.10 vs. 0.37 kg, respectively). Both methods showed strong agreement for [INCREMENT]%BF (r = 0.75; standard error of the estimate [SEE] = 1.15%), [INCREMENT]FM (r = 0.84; SEE 1.0 kg), and [INCREMENT]FFM (r = 0.71; SEE of 1.5 kg). The 2 methods were poor predictors of each other in regards to changes in segmental measurements. Our data indicate that MF-BIA is an acceptable alternative for tracking changes in FM and FFM during a combined diet and exercise program in young, athletic men, but segmental lean mass measurements must be interpreted with circumspection.

Stress and Damage in Polymer Matrix Composite Materials Due to Material Degradation at High Temperatures

NASA Technical Reports Server (NTRS)

McManus, Hugh L.; Chamis, Christos C.

1996-01-01

This report describes analytical methods for calculating stresses and damage caused by degradation of the matrix constituent in polymer matrix composite materials. Laminate geometry, material properties, and matrix degradation states are specified as functions of position and time. Matrix shrinkage and property changes are modeled as functions of the degradation states. The model is incorporated into an existing composite mechanics computer code. Stresses, strains, and deformations at the laminate, ply, and micro levels are calculated, and from these calculations it is determined if there is failure of any kind. The rationale for the model (based on published experimental work) is presented, its integration into the laminate analysis code is outlined, and example results are given, with comparisons to existing material and structural data. The mechanisms behind the changes in properties and in surface cracking during long-term aging of polyimide matrix composites are clarified. High-temperature-material test methods are also evaluated.

Electron Beam-Cure Polymer Matrix Composites: Processing and Properties

NASA Technical Reports Server (NTRS)

Wrenn, G.; Frame, B.; Jensen, B.; Nettles, A.

2001-01-01

Researchers from NASA and Oak Ridge National Laboratory are evaluating a series of electron beam curable composites for application in reusable launch vehicle airframe and propulsion systems. Objectives are to develop electron beam curable composites that are useful at cryogenic to elevated temperatures (-217 C to 200 C), validate key mechanical properties of these composites, and demonstrate cost-saving fabrication methods at the subcomponent level. Electron beam curing of polymer matrix composites is an enabling capability for production of aerospace structures in a non-autoclave process. Payoffs of this technology will be fabrication of composite structures at room temperature, reduced tooling cost and cure time, and improvements in component durability. This presentation covers the results of material property evaluations for electron beam-cured composites made with either unidirectional tape or woven fabric architectures. Resin systems have been evaluated for performance in ambient, cryogenic, and elevated temperature conditions. Results for electron beam composites and similar composites cured in conventional processes are reviewed for comparison. Fabrication demonstrations were also performed for electron beam-cured composite airframe and propulsion piping subcomponents. These parts have been built to validate manufacturing methods with electron beam composite materials, to evaluate electron beam curing processing parameters, and to demonstrate lightweight, low-cost tooling options.

Comparison of Requirements for Composite Structures for Aircraft and Space Applications

NASA Technical Reports Server (NTRS)

Raju, Ivatury S.; Elliot, Kenny B.; Hampton, Roy W.; Knight, Norman F., Jr.; Aggarwal, Pravin; Engelstad, Stephen P.; Chang, James B.

2010-01-01

In this report, the aircraft and space vehicle requirements for composite structures are compared. It is a valuable exercise to study composite structural design approaches used in the airframe industry and to adopt methodology that is applicable for space vehicles. The missions, environments, analysis methods, analysis validation approaches, testing programs, build quantities, inspection, and maintenance procedures used by the airframe industry, in general, are not transferable to spaceflight hardware. Therefore, while the application of composite design approaches from aircraft and other industries is appealing, many aspects cannot be directly utilized. Nevertheless, experiences and research for composite aircraft structures may be of use in unexpected arenas as space exploration technology develops, and so continued technology exchanges are encouraged.

New Polylactic Acid Composites Reinforced with Artichoke Fibers

PubMed Central

Botta, Luigi; Fiore, Vincenzo; Scalici, Tommaso; Valenza, Antonino; Scaffaro, Roberto

2015-01-01

In this work, artichoke fibers were used for the first time to prepare poly(lactic acid) (PLA)-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w) were prepared by the film-stacking method: the first one (UNID) reinforced with unidirectional long artichoke fibers, the second one (RANDOM) reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanical tests. The morphology of the fracture surfaces was analyzed through scanning electron microscopy (SEM). Moreover, a theoretical model, i.e., Hill’s method, was used to fit the experimental Young’s modulus of the biocomposites. The quasi-static tensile tests revealed that the modulus of UNID composites is significantly higher than that of the neat PLA (i.e., ~40%). Moreover, the tensile strength is slightly higher than that of the neat matrix. The other way around, the stiffness of RANDOM composites is not significantly improved, and the tensile strength decreases in comparison to the neat PLA.

Using the concept of pseudo amino acid composition to predict resistance gene against Xanthomonas oryzae pv. oryzae in rice: an approach from chaos games representation.

PubMed

Jingbo, Xia; Silan, Zhang; Feng, Shi; Huijuan, Xiong; Xuehai, Hu; Xiaohui, Niu; Zhi, Li

2011-09-07

To evaluate the possibility of an unknown protein to be a resistant gene against Xanthomonas oryzae pv. oryzae, a different mode of pseudo amino acid composition (PseAAC) is proposed to formulate the protein samples by integrating the amino acid composition, as well as the Chaos games representation (CGR) method. Some numerical comparisons of triangle, quadrangle and 12-vertex polygon CGR are carried to evaluate the efficiency of using these fractal figures in classifiers. The numerical results show that among the three polygon methods, triangle method owns a good fractal visualization and performs the best in the classifier construction. By using triangle + 12-vertex polygon CGR as the mathematical feature, the classifier achieves 98.13% in Jackknife test and MCC achieves 0.8462. Copyright © 2011 Elsevier Ltd. All rights reserved.

Trade-offs in sensitivity and sampling depth in bimodal atomic force microscopy and comparison to the trimodal case

PubMed Central

Eslami, Babak; Ebeling, Daniel

2014-01-01

Summary This paper presents experiments on Nafion® proton exchange membranes and numerical simulations illustrating the trade-offs between the optimization of compositional contrast and the modulation of tip indentation depth in bimodal atomic force microscopy (AFM). We focus on the original bimodal AFM method, which uses amplitude modulation to acquire the topography through the first cantilever eigenmode, and drives a higher eigenmode in open-loop to perform compositional mapping. This method is attractive due to its relative simplicity, robustness and commercial availability. We show that this technique offers the capability to modulate tip indentation depth, in addition to providing sample topography and material property contrast, although there are important competing effects between the optimization of sensitivity and the control of indentation depth, both of which strongly influence the contrast quality. Furthermore, we demonstrate that the two eigenmodes can be highly coupled in practice, especially when highly repulsive imaging conditions are used. Finally, we also offer a comparison with a previously reported trimodal AFM method, where the above competing effects are minimized. PMID:25161847

Breaking the Sound Barrier with a Hummingbird's Index to Musical Themes.

ERIC Educational Resources Information Center

Bauer, Harry C.

1978-01-01

This review of Denys Parsons'"Directory of Tunes and Musical Themes" describes its simple but effective method of identifying musical compositions. Comparisons are made with other prominent musical reference works, particularly those of Harold Barlow and Sam Morgenstern. (JD)

Food composition database development for between country comparisons.

PubMed

Merchant, Anwar T; Dehghan, Mahshid

2006-01-19

Nutritional assessment by diet analysis is a two-stepped process consisting of evaluation of food consumption, and conversion of food into nutrient intake by using a food composition database, which lists the mean nutritional values for a given food portion. Most reports in the literature focus on minimizing errors in estimation of food consumption but the selection of a specific food composition table used in nutrient estimation is also a source of errors. We are conducting a large prospective study internationally and need to compare diet, assessed by food frequency questionnaires, in a comparable manner between different countries. We have prepared a multi-country food composition database for nutrient estimation in all the countries participating in our study. The nutrient database is primarily based on the USDA food composition database, modified appropriately with reference to local food composition tables, and supplemented with recipes of locally eaten mixed dishes. By doing so we have ensured that the units of measurement, method of selection of foods for testing, and assays used for nutrient estimation are consistent and as current as possible, and yet have taken into account some local variations. Using this common metric for nutrient assessment will reduce differential errors in nutrient estimation and improve the validity of between-country comparisons.

Nonlinear electroelastic deformations of dielectric elastomer composites: II - Non-Gaussian elastic dielectrics

NASA Astrophysics Data System (ADS)

Lefèvre, Victor; Lopez-Pamies, Oscar

2017-02-01

This paper presents an analytical framework to construct approximate homogenization solutions for the macroscopic elastic dielectric response - under finite deformations and finite electric fields - of dielectric elastomer composites with two-phase isotropic particulate microstructures. The central idea consists in employing the homogenization solution derived in Part I of this work for ideal elastic dielectric composites within the context of a nonlinear comparison medium method - this is derived as an extension of the comparison medium method of Lopez-Pamies et al. (2013) in nonlinear elastostatics to the coupled realm of nonlinear electroelastostatics - to generate in turn a corresponding solution for composite materials with non-ideal elastic dielectric constituents. Complementary to this analytical framework, a hybrid finite-element formulation to construct homogenization solutions numerically (in three dimensions) is also presented. The proposed analytical framework is utilized to work out a general approximate homogenization solution for non-Gaussian dielectric elastomers filled with nonlinear elastic dielectric particles that may exhibit polarization saturation. The solution applies to arbitrary (non-percolative) isotropic distributions of filler particles. By construction, it is exact in the limit of small deformations and moderate electric fields. For finite deformations and finite electric fields, its accuracy is demonstrated by means of direct comparisons with finite-element solutions. Aimed at gaining physical insight into the extreme enhancement in electrostriction properties displayed by emerging dielectric elastomer composites, various cases wherein the filler particles are of poly- and mono-disperse sizes and exhibit different types of elastic dielectric behavior are discussed in detail. Contrary to an initial conjecture in the literature, it is found (inter alia) that the isotropic addition of a small volume fraction of stiff (semi-)conducting/high-permittivity particles to dielectric elastomers does not lead to the extreme electrostriction enhancements observed in experiments. It is posited that such extreme enhancements are the manifestation of interphasial phenomena.

Characterization of low concentration uranium glass working materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eppich, G. R.; Wimpenny, J. B.; Leever, M. E.

A series of uranium-doped silicate glasses were created at (Lawrence Livermore National Laboratory) LLNL, to be used as working reference material analogs for low uranium concentration research. Specifically, the aim of this effort was the generation of well-characterized glasses spanning a range of concentrations and compositions, and of sufficient homogeneity in uranium concentration and isotopic composition, for instrumentation research and development purposes. While the glasses produced here are not intended to replace or become standard materials for uranium concentration or uranium isotopic composition, it is hoped that they will help fill a current gap, providing low-level uranium glasses sufficient formore » methods development and method comparisons within the limitations of the produced glass suite. Glasses are available for research use by request.« less

Method comparison for forest soil carbon and nitrogen estimates in the Delaware River basin

Treesearch

B. Xu; Yude Pan; A.H. Johnson; A.F. Plante

2016-01-01

The accuracy of forest soil C and N estimates is hampered by forest soils that are rocky, inaccessible, and spatially heterogeneous. A composite coring technique is the standard method used in Forest Inventory and Analysis, but its accuracy has been questioned. Quantitative soil pits provide direct measurement of rock content and soil mass from a larger, more...

Evaluation of a Variable-Impedance Ceramic Matrix Composite Acoustic Liner

NASA Technical Reports Server (NTRS)

Jones, M. G.; Watson, W. R.; Nark, D. M.; Howerton, B. M.

2014-01-01

As a result of significant progress in the reduction of fan and jet noise, there is growing concern regarding core noise. One method for achieving core noise reduction is via the use of acoustic liners. However, these liners must be constructed with materials suitable for high temperature environments and should be designed for optimum absorption of the broadband core noise spectrum. This paper presents results of tests conducted in the NASA Langley Liner Technology Facility to evaluate a variable-impedance ceramic matrix composite acoustic liner that offers the potential to achieve each of these goals. One concern is the porosity of the ceramic matrix composite material, and whether this might affect the predictability of liners constructed with this material. Comparisons between two variable-depth liners, one constructed with ceramic matrix composite material and the other constructed via stereolithography, are used to demonstrate this material porosity is not a concern. Also, some interesting observations are noted regarding the orientation of variable-depth liners. Finally, two propagation codes are validated via comparisons of predicted and measured acoustic pressure profiles for a variable-depth liner.

Alignment-free genetic sequence comparisons: a review of recent approaches by word analysis

PubMed Central

Steele, Joe; Bastola, Dhundy

2014-01-01

Modern sequencing and genome assembly technologies have provided a wealth of data, which will soon require an analysis by comparison for discovery. Sequence alignment, a fundamental task in bioinformatics research, may be used but with some caveats. Seminal techniques and methods from dynamic programming are proving ineffective for this work owing to their inherent computational expense when processing large amounts of sequence data. These methods are prone to giving misleading information because of genetic recombination, genetic shuffling and other inherent biological events. New approaches from information theory, frequency analysis and data compression are available and provide powerful alternatives to dynamic programming. These new methods are often preferred, as their algorithms are simpler and are not affected by synteny-related problems. In this review, we provide a detailed discussion of computational tools, which stem from alignment-free methods based on statistical analysis from word frequencies. We provide several clear examples to demonstrate applications and the interpretations over several different areas of alignment-free analysis such as base–base correlations, feature frequency profiles, compositional vectors, an improved string composition and the D2 statistic metric. Additionally, we provide detailed discussion and an example of analysis by Lempel–Ziv techniques from data compression. PMID:23904502

System-on-chip integration of a new electromechanical impedance calculation method for aircraft structure health monitoring.

PubMed

Boukabache, Hamza; Escriba, Christophe; Zedek, Sabeha; Medale, Daniel; Rolet, Sebastien; Fourniols, Jean Yves

2012-10-11

The work reported on this paper describes a new methodology implementation for active structural health monitoring of recent aircraft parts made from carbon-fiber-reinforced polymer. This diagnosis is based on a new embedded method that is capable of measuring the local high frequency impedance spectrum of the structure through the calculation of the electro-mechanical impedance of a piezoelectric patch pasted non-permanently onto its surface. This paper involves both the laboratory based E/M impedance method development, its implementation into a CPU with limited resources as well as a comparison with experimental testing data needed to demonstrate the feasibility of flaw detection on composite materials and answer the question of the method reliability. The different development steps are presented and the integration issues are discussed. Furthermore, we present the unique advantages that the reconfigurable electronics through System-on-Chip (SoC) technology brings to the system scaling and flexibility. At the end of this article, we demonstrate the capability of a basic network of sensors mounted onto a real composite aircraft part specimen to capture its local impedance spectrum signature and to diagnosis different delamination sizes using a comparison with a baseline.

System-on-Chip Integration of a New Electromechanical Impedance Calculation Method for Aircraft Structure Health Monitoring

PubMed Central

Boukabache, Hamza; Escriba, Christophe; Zedek, Sabeha; Medale, Daniel; Rolet, Sebastien; Fourniols, Jean Yves

2012-01-01

The work reported on this paper describes a new methodology implementation for active structural health monitoring of recent aircraft parts made from carbon-fiber-reinforced polymer. This diagnosis is based on a new embedded method that is capable of measuring the local high frequency impedance spectrum of the structure through the calculation of the electro-mechanical impedance of a piezoelectric patch pasted non-permanently onto its surface. This paper involves both the laboratory based E/M impedance method development, its implementation into a CPU with limited resources as well as a comparison with experimental testing data needed to demonstrate the feasibility of flaw detection on composite materials and answer the question of the method reliability. The different development steps are presented and the integration issues are discussed. Furthermore, we present the unique advantages that the reconfigurable electronics through System-on-Chip (SoC) technology brings to the system scaling and flexibility. At the end of this article, we demonstrate the capability of a basic network of sensors mounted onto a real composite aircraft part specimen to capture its local impedance spectrum signature and to diagnosis different delamination sizes using a comparison with a baseline. PMID:23202013

Composite polymer-containing coatings on Mg alloys perspective for industry and implant surgery

NASA Astrophysics Data System (ADS)

Gnedenkov, S. V.; Sinebryukhov, S. L.; Mashtalyar, D. V.; Imshinetskiy, I. M.; Gnedenkov, A. S.; Minaev, A. N.

2017-09-01

In order to improve the corrosion resistance of magnesium alloys the ways of composite protective coating formation were developed by means of plasma electrolytic oxidation (PEO) as well as electrophoretic deposition methods. Electrochemical, corrosion, tribological, and morphological properties of the MAS magnesium alloy composite coatings were studied. The composite polymer-containing coating decrease the corrosion current density values by three orders of magnitude (Ic = 2.0 . 10-10 A/cm2), in comparison with the base PEO-layer. These polymer-containing layers enable one to expand the practical usage area of Mg alloys. The application of such coatings provides the increasing the bioactivity and regulate the corrosion rate of resorbable magnesium implants.

Multi-Scale Modeling of an Integrated 3D Braided Composite with Applications to Helicopter Arm

NASA Astrophysics Data System (ADS)

Zhang, Diantang; Chen, Li; Sun, Ying; Zhang, Yifan; Qian, Kun

2017-10-01

A study is conducted with the aim of developing multi-scale analytical method for designing the composite helicopter arm with three-dimensional (3D) five-directional braided structure. Based on the analysis of 3D braided microstructure, the multi-scale finite element modeling is developed. Finite element analysis on the load capacity of 3D five-directional braided composites helicopter arm is carried out using the software ABAQUS/Standard. The influences of the braiding angle and loading condition on the stress and strain distribution of the helicopter arm are simulated. The results show that the proposed multi-scale method is capable of accurately predicting the mechanical properties of 3D braided composites, validated by the comparison the stress-strain curves of meso-scale RVCs. Furthermore, it is found that the braiding angle is an important factor affecting the mechanical properties of 3D five-directional braided composite helicopter arm. Based on the optimized structure parameters, the nearly net-shaped composite helicopter arm is fabricated using a novel resin transfer mould (RTM) process.

Simulation of Guided Wave Interaction with In-Plane Fiber Waviness

NASA Technical Reports Server (NTRS)

Leckey, Cara A. C.; Juarez, Peter D.

2016-01-01

Reducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA's Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoing work at NASA Langley is focused on expanding ultrasonic simulation capabilities for composite materials. Simulation tools can be used to guide the development of optimal inspection methods. Custom code based on elastodynamic finite integration technique is currently being developed and implemented to study ultrasonic wave interaction with manufacturing defects, such as in-plane fiber waviness (marcelling). This paper describes details of validation comparisons performed to enable simulation of guided wave propagation in composites containing fiber waviness. Simulation results for guided wave interaction with in-plane fiber waviness are also discussed. The results show that the wavefield is affected by the presence of waviness on both the surface containing fiber waviness, as well as the opposite surface to the location of waviness.

Simulation of guided wave interaction with in-plane fiber waviness

NASA Astrophysics Data System (ADS)

Leckey, Cara A. C.; Juarez, Peter D.

2017-02-01

Reducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA's Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoing work at NASA Langley is focused on expanding ultrasonic simulation capabilities for composite materials. Simulation tools can be used to guide the development of optimal inspection methods. Custom code based on elastodynamic finite integration technique is currently being developed and implemented to study ultrasonic wave interaction with manufacturing defects, such as in-plane fiber waviness (marcelling). This paper describes details of validation comparisons performed to enable simulation of guided wave propagation in composites containing fiber waviness. Simulation results for guided wave interaction with in-plane fiber waviness are also discussed. The results show that the wavefield is affected by the presence of waviness on both the surface containing fiber waviness, as well as the opposite surface to the location of waviness.

Towards a Probabilistic Preliminary Design Criterion for Buckling Critical Composite Shells

NASA Technical Reports Server (NTRS)

Arbocz, Johann; Hilburger, Mark W.

2003-01-01

A probability-based analysis method for predicting buckling loads of compression-loaded laminated-composite shells is presented, and its potential as a basis for a new shell-stability design criterion is demonstrated and discussed. In particular, a database containing information about specimen geometry, material properties, and measured initial geometric imperfections for a selected group of laminated-composite cylindrical shells is used to calculate new buckling-load "knockdown factors". These knockdown factors are shown to be substantially improved, and hence much less conservative than the corresponding deterministic knockdown factors that are presently used by industry. The probability integral associated with the analysis is evaluated by using two methods; that is, by using the exact Monte Carlo method and by using an approximate First-Order Second- Moment method. A comparison of the results from these two methods indicates that the First-Order Second-Moment method yields results that are conservative for the shells considered. Furthermore, the results show that the improved, reliability-based knockdown factor presented always yields a safe estimate of the buckling load for the shells examined.

Open Circuit Resonant (SansEC) Sensor Technology for Lightning Mitigation and Damage Detection and Diagnosis for Composite Aircraft Applications

NASA Technical Reports Server (NTRS)

Szatkowski, George N.; Dudley, Kenneth L.; Smith, Laura J.; Wang, Chuantong; Ticatch, Larry A.

2014-01-01

Traditional methods to protect composite aircraft from lightning strike damage rely on a conductive layer embedded on or within the surface of the aircraft composite skin. This method is effective at preventing major direct effect damage and minimizes indirect effects to aircraft systems from lightning strike attachment, but provides no additional benefit for the added parasitic weight from the conductive layer. When a known lightning strike occurs, the points of attachment and detachment on the aircraft surface are visually inspected and checked for damage by maintenance personnel to ensure continued safe flight operations. A new multi-functional lightning strike protection (LSP) method has been developed to provide aircraft lightning strike protection, damage detection and diagnosis for composite aircraft surfaces. The method incorporates a SansEC sensor array on the aircraft exterior surfaces forming a "Smart skin" surface for aircraft lightning zones certified to withstand strikes up to 100 kiloamperes peak current. SansEC sensors are open-circuit devices comprised of conductive trace spiral patterns sans (without) electrical connections. The SansEC sensor is an electromagnetic resonator having specific resonant parameters (frequency, amplitude, bandwidth & phase) which when electromagnetically coupled with a composite substrate will indicate the electrical impedance of the composite through a change in its resonant response. Any measureable shift in the resonant characteristics can be an indication of damage to the composite caused by a lightning strike or from other means. The SansEC sensor method is intended to diagnose damage for both in-situ health monitoring or ground inspections. In this paper, the theoretical mathematical framework is established for the use of open circuit sensors to perform damage detection and diagnosis on carbon fiber composites. Both computational and experimental analyses were conducted to validate this new method and system for aircraft composite damage detection and diagnosis. Experimental test results on seeded fault damage coupons and computational modeling simulation results are presented. This paper also presents the shielding effectiveness along with the lightning direct effect test results from several different SansEC LSP and baseline protected and unprotected carbon fiber reinforced polymer (CFRP) test panels struck at 40 and 100 kiloamperes following a universal common practice test procedure to enable damage comparisons between SansEC LSP configurations and common practice copper mesh LSP approaches. The SansEC test panels were mounted in a LSP test bed during the lightning test. Electrical, mechanical and thermal parameters were measured during lightning attachment and are presented with post test nondestructive inspection comparisons. The paper provides correlational results between the SansEC sensors computed electric field distribution and the location of the lightning attachment on the sensor trace and visual observations showing the SansEC sensor's affinity for dispersing the lightning attachment.

New Numerical Approaches To thermal Convection In A Compositionally Stratified Fluid

NASA Astrophysics Data System (ADS)

Puckett, E. G.; Turcotte, D. L.; Kellogg, L. H.; Lokavarapu, H. V.; He, Y.; Robey, J.

2016-12-01

Seismic imaging of the mantle has revealed large and small scale heterogeneities in the lower mantle; specifically structures known as large low shear velocity provinces (LLSVP) below Africa and the South Pacific. Most interpretations propose that the heterogeneities are compositional in nature, differing from the overlying mantle, an interpretation that would be consistent with chemical geodynamic models. The LLSVP's are thought to be very old, meaning they have persisted thoughout much of Earth's history. Numerical modeling of persistent compositional interfaces present challenges to even state-of-the-art numerical methodology. It is extremely difficult to maintain sharp composition boundaries which migrate and distort with time dependent fingering without compositional diffusion and / or artificial diffusion. The compositional boundary must persist indefinitely. In this work we present computations of an initial compositionally stratified fluid that is subject to a thermal gradient ΔT = T1 - T0 across the height D of a rectangular domain over a range of buoyancy numbers B and Rayleigh numbers Ra. In these computations we compare three numerical approaches to modeling the movement of two distinct, thermally driven, compositional fields; namely, a high-order Finte Element Method (FEM) that employs artifical viscosity to preserve the maximum and minimum values of the compositional field, a Discontinous Galerkin (DG) method with a Bound Preserving (BP) limiter, and a Volume-of-Fluid (VOF) interface tracking algorithm. Our computations demonstrate that the FEM approach has far too much numerical diffusion to yield meaningful results, the DGBP method yields much better resuts but with small amounts of each compositional field being (numerically) entrained within the other compositional field, while the VOF method maintains a sharp interface between the two compositions throughout the computation. In the figure we show a comparison of between the three methods for a computation made with B = 1.111 and Ra = 10,000 after the flow has reached 'steady state'. (R) the images computed with the standard FEM method (with artifical viscosity), (C) the images computed with the DGBP method (with no artifical viscosity or diffusion due to discretization errors) and (L) the images computed with the VOF algorithm.

Effect of Interface Modified by Graphene on the Mechanical and Frictional Properties of Carbon/Graphene/Carbon Composites

PubMed Central

Yang, Wei; Luo, Ruiying; Hou, Zhenhua

2016-01-01

In this work, we developed an interface modified by graphene to simultaneously improve the mechanical and frictional properties of carbon/graphene/carbon (C/G/C) composite. Results indicated that the C/G/C composite exhibits remarkably improved interfacial bonding mode, static and dynamic mechanical performance, thermal conductivity, and frictional properties in comparison with those of the C/C composite. The weight contents of carbon fibers, graphene and pyrolytic carbon are 31.6, 0.3 and 68.1 wt %, respectively. The matrix of the C/G/C composite was mainly composed of rough laminar (RL) pyrocarbon. The average hardness by nanoindentation of the C/G/C and C/C composite matrices were 0.473 and 0.751 GPa, respectively. The flexural strength (three point bending), interlaminar shear strength (ILSS), interfacial debonding strength (IDS), internal friction and storage modulus of the C/C composite were 106, 10.3, 7.6, 0.038 and 12.7 GPa, respectively. Those properties of the C/G/C composite increased by 76.4%, 44.6%, 168.4% and 22.8%, respectively, and their internal friction decreased by 42.1% in comparison with those of the C/C composite. Owing to the lower hardness of the matrix, improved fiber/matrix interface bonding strength, and self-lubricating properties of graphene, a complete friction film was easily formed on the friction surface of the modified composite. Compared with the C/C composite, the C/G/C composite exhibited stable friction coefficients and lower wear losses at simulating air-plane normal landing (NL) and rejected take-off (RTO). The method appears to be a competitive approach to improve the mechanical and frictional properties of C/C composites simultaneously. PMID:28773613

Comparison of Composition and Anticaries Effect of Galla Chinensis Extracts with Different Isolation Methods

PubMed Central

Huang, Xuelian; Deng, Meng; Liu, Mingdong; Cheng, Lei; Exterkate, R.A.M.; Li, Jiyao; Zhou, Xuedong; Ten Cate, Jacob. M.

2017-01-01

Objectives: Galla chinensis water extract (GCE) has been demonstrated to inhibit dental caries by favorably shifting the demineralization/remineralization balance of enamel and inhibiting the biomass and acid formation of dental biofilm. The present study focused on the comparison of composition and anticaries effect of Galla chinensis extracts with different isolation methods, aiming to improve the efficacy of caries prevention. Methods: The composition of water extract (GCE), ethanol extract (eGCE) and commercial tannic acid was compared. High performance liquid chromatography coupled to electrospray ionization-time of flight-mass spectrometry (HPLC-ESI-TOF-MS) analysis was used to analyze the main ingredients. In vitro pH-cycling regime and polymicrobial biofilms model were used to assess the ability of different Galla chinensis extracts to inhibit enamel demineralization, acid formation and biofilm formation. Results: All the GCE, eGCE and tannic acid contained a high level of total phenolics. HPLC-ESI-TOF-MS analysis showed that the main ingredients of GCE were gallic acid (GA), while eGCE mainly contained 4-7 galloylglucopyranoses (GGs) and tannic acid mainly contained 5-10 GGs. Furthermore, eGCE and tannic acid showed a better effect on inhibiting enamel demineralization, acid formation and biofilm formation compared to GCE. Conclusions: Galla chinensis extracts with higher tannin content were suggested to have higher potential to prevent dental caries. PMID:28979574

Comparison of two methods of visual magnification for removal of adhesive flash during bracket placement using two types of orthodontic bonding agents

PubMed Central

Alencar, Estefania Queiroga de Santana e; Nobrega, Maria de Lourdes Martins; Dametto, Fabio Roberto; dos Santos, Patrícia Bittencourt Dutra; Pinheiro, Fabio Henrique de Sá Leitão

2016-01-01

ABSTRACT Objective: This study aimed to evaluate the effectiveness of two methods of visual magnification (operating microscope and light head magnifying glass) for removal of composite flash around orthodontic metal brackets. Material and Methods: Brackets were bonded in the center of the clinical crown of sixty well-preserved human premolars. Half of the sample was bonded with conventional Transbond XT (3M Unitek TM, USA), whereas the other half was bonded with Transbond TM Plus Color Change (3M Unitek TM, USA). For each type of composite, the choice of method to remove the flash was determined by randomly distributing the teeth into the following subgroups: A (removal by naked eye, n = 10), B (removal with the aid of light head magnifying glass, under 4x magnification, n = 10), and C (removal with the aid of an operating microscope, under 40x magnification, n = 10). Brackets were debonded and teeth taken to a scanning electron microscope (SS-x-550, Shimadzu, Japan) for visualization of their buccal surface. Quantification of composite flash was performed with Image Pro Plus software, and values were compared by Kruskal-Wallis test and Dunn’s post-hoc test at 5% significance level. Results: Removal of pigmented orthodontic adhesive with the aid of light head magnifying glass proved, in general, to be advantageous in comparison to all other methods. Conclusion: There was no advantage in using Transbond TM Plus Color Change alone. Further studies are necessary to draw a more definitive conclusion in regards to the benefits of using an operating microscope. PMID:28125139

Measuring delta volumetric change and composition using a streakline-based method on the Wax Lake Delta

NASA Astrophysics Data System (ADS)

Hurlbut, K.; Estep, J. D.; Shaw, J.; Edmonds, D. A.

2016-12-01

Estimating river delta growth is essential for determining coastal sustainability. We use a new method to quantify the recent accretion and composition of the Wax Lake Delta, a rapidly prograding delta in Louisiana. The method identifies the area of significant (subaqueous) delta aggradation from delta flow patterns, which are visible in aerial imagery through biogenic streaklines that naturally occur on the water surface. Comparison of bathymetric maps and streaklines shows that channel tips and the associated seaward extent of significant delta deposition occur where the divergence of flow direction equals 0 (+/- 400 m). Delta volumes calculated using this method, the 1974 pre-delta shoreline, and a measured average delta thickness of 1.6 m provide an estimate of the delta volume which we found to increase by 2.0*106 m3/yr between 1992 and 2014. We then compared this rate to the total volume of silt and sand discharged to the WLD using USGS measurements. Over the same period, the WLD received 1.4*106 m3/yr of sand and 9.0*106 m3/yr of silt and clay. Assuming all sand supplied to the delta is sequestered, volume comparisons show that the sand fraction of the WLD is between 18-38%, lower than previous estimates. Further, between 44-69% of the total suspended silt and clay bypasses the delta. These composition estimates can be used to predict land growth from engineered diversions, and the method can be used to monitor the resulting delta growth.

Comparison of Notch Strength between Gr/PEEK (APC-1 and APC-2) and Gr/Epoxy Composite Materials at Elevated Temperature.

DTIC Science & Technology

1985-12-01

J ub. we Jr. Captain, USARt Z712 AFIT/GAE/AA/85D- 12 Iv COMPARISON OF NOTCH STRENGTH BETWEEN GR/PEEK (APC-1 AND APC-2) AND GR/EPOXY COMPOSITE ...85D-12 COMPARISON OF NOTCH STRENGTH BETWEEN GR/PEEK _ (APC-1 AND APC-2) AND GR/EPOXY COMPOSITE MATERIAL AT ELEVATED TEMPERATURE THESIS Presented to the...unlimited Preface In this experimental investigation, the reduction of strength for notched composite laminates of Aromatic Polymer Composite , APC-2

Iterative fitting method for the evaluation and quantification of PAES spectra

NASA Astrophysics Data System (ADS)

Zimnik, Samantha; Hackenberg, Mathias; Hugenschmidt, Christoph

2017-01-01

The elemental composition of surfaces is of great importance for the understanding of many surface processes such as catalysis. For a reliable analysis and a comparison of results, the quantification of the measured data is indispensable. Positron annihilation induced Auger Electron Spectroscopy (PAES) is a spectroscopic technique that measures the elemental composition with outstanding surface sensitivity, but up to now, no standardized evaluation procedure for PAES spectra is available. In this paper we present a new approach for the evaluation of PAES spectra of compounds, using the spectra obtained for the pure elements as reference. The measured spectrum is then fitted by a linear combination of the reference spectra by varying their intensities. The comparison of the results of the fitting routine with a calculation of the full parameter range shows an excellent agreement. We present the results of the new analysis method to evaluate the PAES spectra of sub-monolayers of Ni on a Pd substrate.

Study on Fatigue Performance of Composite Bolted Joints with Bolt-Hole Delamination

NASA Astrophysics Data System (ADS)

Liu, M. J.; Yu, S.; Zhao, Q. Y.

2018-03-01

Fatigue performance of composite structure with imperfections is a challenging subject at present. Based on cohesive zone method and multi-continuum theory, delamination evolution response and fatigue life prediction of a 3D composite single-lap joint with a bolt-hole have been investigated through computer codes Abaqus and Fe-safe. Results from the comparison of a perfect composite bolted joint with another defect one indicates that a relatively small delamination damage around the bolt hole brings about significant degradation of local material performance. More notably, fatigue life of stress concentration region of composite bolted joints is highly sensitive to external loads, as an increase of 67% cyclic load amplitude leads to an decrease of 99.5% local fatigue life in this study. However, the numerical strategy for solving composite fatigue problems is meaningful to engineering works.

HIV-associated cognitive disorders in perinatally infected children and adolescents: a novel composite cognitive domains score.

PubMed

Phillips, Nicole J; Hoare, Jacqueline; Stein, Dan J; Myer, Landon; Zar, Heather J; Thomas, Kevin G F

2018-04-22

Accurate assessment of HIV-associated cognitive disorders in perinatally infected children and adolescents is challenging. Assessments of general intellectual functioning, or global cognition, may not provide information regarding domain-specific strengths and weaknesses, and may therefore fail to detect, impaired trajectories of development within particular cognitive domains. We compare the efficacy of global cognitive scores to that of composite cognitive domain scores in detecting cognitive disorders in a sample of perinatally HIV-infected children, and a demographically matched HIV negative control group, drawn from the Cape Town Adolescent Antiretroviral Cohort (CTAAC) study. All children were administered a comprehensive neuropsychological test battery. Using data from that test battery, we created ten separate composite cognitive domains: general intellectual functioning, attention, working memory, visual memory, verbal memory, language, visual spatial ability, motor coordination, processing speed and executive function. Within each domain, each test bore a high level of association with each of the other tests in that domain (Cronbach's α ≥ .70 for all domains). We found that composite domain scores calculated on whole-sample data were significantly higher than those calculated using control-sample data. Our comparison of a global cognitive score to composite domain scores suggested that the latter provided more detailed information (regarding strengths, weaknesses, areas of impairment), and when compared to global scores, were more sensitive in detecting HIV-associated cognitive disorders, and were able to distinguish HIV-infected patients from uninfected controls. Hence, we recommend using this method of composite cognitive domains scores, rather than global aggregate scores, when assessing cognitive function in paediatric HIV. This method provides a convenient and relatively accurate assessment that might help with cross-cultural and cross-region comparisons as researchers try to detect cognitive impairment patterns in HIV-infected children and adolescents globally.

Predicting the mineral composition of dust aerosols - Part 1: Representing key processes

NASA Astrophysics Data System (ADS)

Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

2015-02-01

Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, coating by heterogeneous uptake of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wet-sieved soil and the resulting aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent in a soil whose aggregates are dispersed by wet sieving during analysis. We reconstruct the undispersed size distribution of the original soil that is subject to wind erosion. An empirical constraint upon the relative emission of clay and silt is applied that further differentiates the soil and aerosol mineral composition. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to measurements from North Africa shows that the extension brings the model into better agreement, consistent with a more extensive comparison to global observations as well as measurements of elemental composition downwind of the Sahara, as described in companion articles.

The failure of 1D seismic model fitting to constrain lower mantle composition

NASA Astrophysics Data System (ADS)

Houser, C. T.; Hernlund, J. W.; Valencia-Cardona, J. J.; Wentzcovitch, R.

2017-12-01

Tests of lower mantle composition models often compare mineral physics data bearing on the elasticity and density of lower mantle phases to the average seismic velocity profile determined by seismology, such a PREM or ak135. We demonstrate why such comparisons between mineralogy and seismology are an inadequate method for definitive discrimination between different scenarios. One issue is that the seismic velocity is more sensitive to temperature than composition for most lower mantle minerals. In practice, this allows one the freedom to choose the geotherm that brings the predicted seismic and density data into agreement with observations. It is commonly assumed that the temperature profile should be adiabatic, however, such a profile presupposes a particular state of the mantle and is only applicable in the absence of layering, buoyancy fluctuations, compositional segregation, and rheological complexities. The mantle temperature should depend on the composition since the latter influences the viscosity of rocks. However, the precise relation between composition, viscosity, and heat transfer would need to be specified, but unfortunately remains highly uncertain. If the mantle contains a mixture of domains with multiple bulk compositions, then the 1D seismic profile comparison is inherently non-unique. Rocks with different bulk composition likely have different isotopic abundances, and can exhibit differing degrees of internal heating and therefore distinct temperatures. Different composition domains can also exhibit variable densities, and tend to congregate at different depths in ways that also affect their thermal evolution and temperature. Therefore, fitting a 1D seismic model alone is an inadequate tool to evaluate lower mantle composition.

Coupled mixed-field laminate theory and finite element for smart piezoelectric composite shell structures

NASA Technical Reports Server (NTRS)

Saravanos, Dimitris A.

1996-01-01

Mechanics for the analysis of laminated composite shells with piezoelectric actuators and sensors are presented. A new mixed-field laminate theory for piezoelectric shells is formulated in curvilinear coordinates which combines single-layer assumptions for the displacements and a layerwise representation for the electric potential. The resultant coupled governing equations for curvilinear piezoelectric laminates are described. Structural mechanics are subsequently developed and an 8-node finite-element is formulated for the static and dynamic analysis of adaptive composite structures of general laminations containing piezoelectric layers. Evaluations of the method and comparisons with reported results are presented for laminated piezoelectric-composite plates, a closed cylindrical shell with a continuous piezoceramic layer and a laminated composite semi-circular cantilever shell with discrete cylindrical piezoelectric actuators and/or sensors.

Formation of protective composite coatings with the use of SPTFE suspensions

NASA Astrophysics Data System (ADS)

Nadaraia, K. V.; Mashtalyar, D. V.; Sinebryukhov, S. L.; Gnedenkov, S. V.

2017-09-01

The method of protective composite coatings formation with the use of the plasma electrolytic oxidation (PEO) and subsequent treatment in isopropanol or aqueous suspension of the superdispersed polytetrafluoroethylene (SPTFE) have been developed. Morphological, electrochemical and tribological studies, as well as wetting ability of the protective coatings have been carried out. The obtained results corroborated the increase of the corrosion and wear resistance parameters for the polymer-containing coating in comparison with the base PEO-coating and uncoated material.

Application of solid/liquid extraction for the gravimetric determination of lipids in royal jelly.

PubMed

Antinelli, Jean-François; Davico, Renée; Rognone, Catherine; Faucon, Jean-Paul; Lizzani-Cuvelier, Louisette

2002-04-10

Gravimetric lipid determination is a major parameter for the characterization and the authentication of royal jelly quality. A solid/liquid extraction was compared to the reference method, which is based on liquid/liquid extraction. The amount of royal jelly and the time of the extraction were optimized in comparison to the reference method. Boiling/rinsing ratio and spread of royal jelly onto the extraction thimble were identified as critical parameters, resulting in good accuracy and precision for the alternative method. Comparison of reproducibility and repeatability of both methods associated with gas chromatographic analysis of the composition of the extracted lipids showed no differences between the two methods. As the intra-laboratory validation tests were comparable to the reference method, while offering rapidity and a decrease in amount of solvent used, it was concluded that the proposed method should be used with no modification of quality criteria and norms established for royal jelly characterization.

Permeability evaluation after decay removal in primary teeth with current caries-excavation techniques.

PubMed

Shabzendedar, Mahbobeh; Moosavi, Horieh; Talbi, Maryam; Sharifi, Marjan

2011-11-01

The goal of the study was to evaluate the effect of caries removal by three various methods on the permeability of class II composite resin restorations in primary molar teeth. Forty-five recently extracted primary molars were randomly assigned to three groups for three different methods of caries removal; group 1-mechanical, group 2-caries detector dye, and group 3-Carisolv (n = 15). After that, class II cavities in all groups were restored with the adhesive (Opti Bond Solo Plus) that was applied according to the manufacturer's instruction and a posterior composite (Herculite XRV), which was used incrementally. After 24 hours the samples were thermocycled in water for 500 cycles between 5 and 55°C with a dwell time of 30 sec. Permeability was assessed by the fluid filtration method. The data were analyzed using the ANOVA test while study groups were compared with Tukey test for statistically significant differences at a 5% significance level. The evaluation of tested groups indicated that the highest (0.80) and least (0.37) mean of permeability was observed in group 2 and 3 respectively. Significant difference was revealed among the tested groups (p = 0.045). The comparison of Carisolv and caries detector dye groups indicated a statistically significant difference (p = 0.037). There was not any significant difference between Carisolv or caries dye in the conventional group. Using the chemomechanical and staining methods for caries removal had no more detrimental effect on permeability than the conventional technique. However, caries detection dye for caries removal could be more harmful than chemomechanical method. None of the current caries-excavation techniques could eliminate permeability in class II composite resin restorations. Furthermore, staining methods do not have an adverse effect on sealing ability in comparison to the conventional technique.

Design and construction of a tensile tester for the testing of simple composites

NASA Technical Reports Server (NTRS)

Borst, Mark A.; Spiegel, F. Xavier

1994-01-01

The following is a design for a tensile tester which will be used to test the tensile strength and anisotropic properties of simple composites. These simple composites are suspected to be anisotropic primarily in a single plane. When the composites undergo a tensile force, they will undergo deformation, causing movement either to the left or right. The composites are suspect due to their method of construction. Each sample has a single layer of unidirectional continuous fibers embedded in a rubbery resin. It has been well established that a serious limitation of unidirectional fiber composites is the very large in-plane anisotropy. The design presented here incorporates a single degree of freedom such that distortion (to the left or right) due to anisotropic tendencies may be measured. The device will spend the vast majority of its time in an undergraduate materials lab. As a result, ease of use and durability are valued more highly than research grade accuracy. Additional concerns focus on the fact that this machine will be built as a student project. Issues which are dealt with during this design include: specimen configuration or shape; a method of applying consistent, linear tension force; a method of gripping specimen without affecting its overall properties; a method of collecting data; repeatability of data; ease of use; ease of construction; and cost. After the device has been constructed, it will be used to test the simple composites which were fabricated in house. A comparison will be made between composites manufactured using aluminum screening as the strengthening fibers and those manufactured using fiberglass screening.

Experimental study and thermodynamic modeling of the Al–Co–Cr–Ni system

DOE PAGES

Gheno, Thomas; Liu, Xuan L.; Lindwall, Greta; ...

2015-09-21

In this study, a thermodynamic database for the Al–Co–Cr–Ni system is built via the Calphad method by extrapolating re-assessed ternary subsystems. A minimum number of quaternary parameters are included, which are optimized using experimental phase equilibrium data obtained by electron probe micro-analysis and x-ray diffraction analysis of NiCoCrAlY alloys spanning a wide compositional range, after annealing at 900 °C, 1100 °C and 1200 °C, and water quenching. These temperatures are relevant to oxidation and corrosion resistant MCrAlY coatings, where M corresponds to some combination of nickel and cobalt. Comparisons of calculated and measured phase compositions show excellent agreement for themore » β–γ equilibrium, and good agreement for three-phase β–γ–σ and β–γ–α equilibria. An extensive comparison with existing Ni-base databases (TCNI6, TTNI8, NIST) is presented in terms of phase compositions.« less

Studies of Cosmic Ray Composition and Air Shower Structure with the Pierre Auger Observatory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abraham, : J.; Abreu, P.; Aglietta, M.

2009-06-01

These are presentations to be presented at the 31st International Cosmic Ray Conference, in Lodz, Poland during July 2009. It consists of the following presentations: (1) Measurement of the average depth of shower maximum and its fluctuations with the Pierre Auger Observatory; (2) Study of the nuclear mass composition of UHECR with the surface detectors of the Pierre Auger Observatory; (3) Comparison of data from the Pierre Auger Observatory with predictions from air shower simulations: testing models of hadronic interactions; (4) A Monte Carlo exploration of methods to determine the UHECR composition with the Pierre Auger Observatory; (5) The delaymore » of the start-time measured with the Pierre Auger Observatory for inclined showers and a comparison of its variance with models; (6) UHE neutrino signatures in the surface detector of the Pierre Auger Observatory; and (7) The electromagnetic component of inclined air showers at the Pierre Auger Observatory.« less

Biometric Subject Verification Based on Electrocardiographic Signals

NASA Technical Reports Server (NTRS)

Dusan, Sorin V. (Inventor); Jorgensen, Charles C. (Inventor)

2014-01-01

A method of authenticating or declining to authenticate an asserted identity of a candidate-person. In an enrollment phase, a reference PQRST heart action graph is provided or constructed from information obtained from a plurality of graphs that resemble each other for a known reference person, using a first graph comparison metric. In a verification phase, a candidate-person asserts his/her identity and presents a plurality of his/her heart cycle graphs. If a sufficient number of the candidate-person's measured graphs resemble each other, a representative composite graph is constructed from the candidate-person's graphs and is compared with a composite reference graph, for the person whose identity is asserted, using a second graph comparison metric. When the second metric value lies in a selected range, the candidate-person's assertion of identity is accepted.

Design and Testing of Braided Composite Fan Case Materials and Components

NASA Technical Reports Server (NTRS)

Roberts, Gary D.; Pereira, J. Michael; Braley, Michael S.; Arnold, William a.; Dorer, James D.; Watson, William R/.

2009-01-01

Triaxial braid composite materials are beginning to be used in fan cases for commercial gas turbine engines. The primary benefit for the use of composite materials is reduced weight and the associated reduction in fuel consumption. However, there are also cost benefits in some applications. This paper presents a description of the braided composite materials and discusses aspects of the braiding process that can be utilized for efficient fabrication of composite cases. The paper also presents an approach that was developed for evaluating the braided composite materials and composite fan cases in a ballistic impact laboratory. Impact of composite panels with a soft projectile is used for materials evaluation. Impact of composite fan cases with fan blades or blade-like projectiles is used to evaluate containment capability. A post-impact structural load test is used to evaluate the capability of the impacted fan case to survive dynamic loads during engine spool down. Validation of these new test methods is demonstrated by comparison with results of engine blade-out tests.

Evaluation of Brazilian Sugarcane Bagasse Characterization: An Interlaboratory Comparison Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sluiter, Justin B.; Chum, Helena; Gomes, Absai C.

2016-05-01

This paper describes a study of the variability of measured composition for a single bulk sugarcane bagasse conducted across eight laboratories using similar analytical methods, with the purpose of determining the expected variation for compositional analysis performed by different laboratories. The results show good agreement of measured composition within a single laboratory, but greater variability when results are compared among laboratories. These interlaboratory variabilities do not seem to be associated with a specific method or technique or any single piece of instrumentation. The summary censored statistics provide mean values and pooled standard deviations as follows: total extractives 6.7% (0.6%), wholemore » ash 1.5% (0.2%), glucan 42.3% (1.2%), xylan 22.3% (0.5%), total lignin 21.3% (0.4%), and total mass closure 99.4% (2.9%).« less

Use of Statistical Analysis of Acoustic Emission Data on Carbon-Epoxy COPV Materials-of-Construction for Enhanced Felicity Ratio Onset Determination

NASA Technical Reports Server (NTRS)

Abraham, Arick Reed A.; Johnson, Kenneth L.; Nichols, Charles T.; Saulsberry, Regor L.; Waller, Jess M.

2012-01-01

Broadband modal acoustic emission (AE) data were acquired during intermittent load hold tensile test profiles on Toray T1000G carbon fiber-reinforced epoxy (C/Ep) single tow specimens. A novel trend seeking statistical method to determine the onset of significant AE was developed, resulting in more linear decreases in the Felicity ratio (FR) with load, potentially leading to more accurate failure prediction. The method developed uses an exponentially weighted moving average (EWMA) control chart. Comparison of the EWMA with previously used FR onset methods, namely the discrete (n), mean (n (raised bar)), normalized (n%) and normalized mean (n(raised bar)%) methods, revealed the EWMA method yields more consistently linear FR versus load relationships between specimens. Other findings include a correlation between AE data richness and FR linearity based on the FR methods discussed in this paper, and evidence of premature failure at lower than expected loads. Application of the EWMA method should be extended to other composite materials and, eventually, composite components such as composite overwrapped pressure vessels. Furthermore, future experiments should attempt to uncover the factors responsible for infant mortality in C/Ep strands.

Calculation of broadband time histories of ground motion: Comparison of methods and validation using strong-ground motion from the 1994 Northridge earthquake

USGS Publications Warehouse

Hartzell, S.; Harmsen, S.; Frankel, A.; Larsen, S.

1999-01-01

This article compares techniques for calculating broadband time histories of ground motion in the near field of a finite fault by comparing synthetics with the strong-motion data set for the 1994 Northridge earthquake. Based on this comparison, a preferred methodology is presented. Ground-motion-simulation techniques are divided into two general methods: kinematic- and composite-fault models. Green's functions of three types are evaluated: stochastic, empirical, and theoretical. A hybrid scheme is found to give the best fit to the Northridge data. Low frequencies ( 1 Hz) are calculated using a composite-fault model with a fractal subevent size distribution and stochastic, bandlimited, white-noise Green's functions. At frequencies below 1 Hz, theoretical elastic-wave-propagation synthetics introduce proper seismic-phase arrivals of body waves and surface waves. The 3D velocity structure more accurately reproduces record durations for the deep sedimentary basin structures found in the Los Angeles region. At frequencies above 1 Hz, scattering effects become important and wave propagation is more accurately represented by stochastic Green's functions. A fractal subevent size distribution for the composite fault model ensures an ??-2 spectral shape over the entire frequency band considered (0.1-20 Hz).

Study of AC Magnetic Properties and Core Losses of Fe/Fe3O4-epoxy Resin Soft Magnetic Composite

NASA Astrophysics Data System (ADS)

Laxminarayana, T. A.; Manna, Subhendu Kumar; Fernandes, B. G.; Venkataramani, N.

Soft Magnetic Composites (SMC) were prepared by coating of nanocrystalline Fe3O4 particles, synthesized by co-precipitation method, on atomized iron powder of particle size less than 53 μm in size using epoxy resin as a binder between iron and Fe3O4. Fe3O4 was chosen, for its high electric resistivity and suitable magnetic properties, to keep the coating layer magnetic and seek improvement to the magnetic properties of SMC. SEM images and XRD patterns were recorded in order to investigate the coatings on the surface of iron powder. A toroid was prepared by cold compaction of coated iron powder at 1050 MPa and subsequently cured at 150˚C for 1 hr in argon atmosphere. For comparison of properties, a toroid of uncoated iron powder was also compacted at 1050 MPa and annealed at 600˚C for 2 hr in argon atmosphere. The coated iron powder composite has a resistivity of greater than 200 μΩm, measured by four probe method. A comparison of Magnetic Hysteresis loops and core losses using B-H Loop tracer in the frequency range 0 to 1500 Hz on the coated and uncoated iron powder is reported.

COMPARISON OF GC-FPD AND GC/AED FOR DETERMINATION OF ORGANOPHOSPHATE PESTICIDES IN COMPOSITE DIET SAMPLES

EPA Science Inventory

In order to assess an individual's total exposure to contaminants in the environment, it is essential that the contribution of dietary exposure be quantified. As a result, USEPA's National Exposure Research Laboratory has initiated a program to develop methods to measure chemical...

Composite Failures: A Comparison of Experimental Test Results and Computational Analysis Using XFEM

DTIC Science & Technology

2016-09-30

NUWC-NPT Technical Report 12,218 30 September 2016 Composite Failures: A Comparison of Experimental Test Results and Computational Analysis...A Comparison of Experimental Test Results and Computational Analysis Using XFEM 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...availability of measurement techniques, experimental testing of composite materials has largely outpaced the computational modeling ability, forcing

Enhanced electrochemical performance of a LTO/carbon nanotubes/graphene composite as an anode material for Li-ion batteries

NASA Astrophysics Data System (ADS)

Wei, Aijia; Li, Wen; Zhang, Lihui; Liu, Zhenfa

2017-09-01

A Li4Ti5O12/carbon nanotubes/graphene composite has been successfully prepared by a solid-state method. For comparison, pure LTO and Li4Ti5O12/graphene composite were also synthesized using the same method. The materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to confirm the structure and morphology. The results reveal that LTO particles are well dispersed and wrapped in the graphene sheets with cross-linked carbon nanotubes. The electrochemical results show that the Li4Ti5O12/carbon nanotubes/graphene composite exhibits the best rate capacity, which lead to a charge capacity of 169.0, 168.5, 167.1, 153.2, 144.5, 131.5 mAh g-1 at 0.2, 0.5, 1, 3, 5 and 10 C, respectively between 1 and 3 V (1 C = 160 mAh g-1). The synergistic effect of graphene and carbon nanotubes constructing 3D networks could enhance the electronic conductivity of Li4Ti5O12/carbon nanotubes/graphene composite.

Stress and Damage in Polymer Matrix Composite Materials Due to Material Degradation at High Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mcmanus, H.L.; Chamis, C.C.

1996-01-01

This report describes analytical methods for calculating stresses and damage caused by degradation of the matrix constituent in polymer matrix composite materials. Laminate geometry, material properties, and matrix degradation states are specified as functions of position and time. Matrix shrinkage and property changes are modeled as functions of the degradation states. The model is incorporated into an existing composite mechanics computer code. Stresses, strains, and deformations at the laminate, ply, and micro levels are calculated, and from these calculations it is determined if there is failure of any kind. The rationale for the model (based on published experimental work) ismore » presented, its integration into the laminate analysis code is outlined, and example results are given, with comparisons to existing material and structural data. The mechanisms behind the changes in properties and in surface cracking during long-term aging of polyimide matrix composites are clarified. High-temperature-material test methods are also evaluated.« less

A comparison of the BAX system method to the U.S. Food and Drug Administration's Bacteriological Analytical Manual and International Organization for Standardization reference methods for the detection of Salmonella in a variety of soy ingredients.

PubMed

Belete, Tamrat; Crowley, Erin; Bird, Patrick; Gensic, Joseph; Wallace, F Morgan

2014-10-01

The performances of two DuPont BAX System PCR assays for detecting Salmonella on a variety of low-moisture soy ingredients were evaluated against the U. S. Food and Drug Administration's Bacteriological Analytical Manual (FDA BAM) method or the International Organization for Standardization (ISO) 6579 reference method. These evaluations were conducted as a single laboratory validation at an ISO 17025 accredited third-party laboratory. Validations were conducted on five soy ingredients: isolated soy protein (ISP), soy fiber, fluid soy lecithin, deoiled soy lecithin, and soy nuggets, using a paired-study design. The ISP was analyzed as both 25- and 375-g composite test portions, whereas all other sample matrices were analyzed as 375-g composite test portions. To evaluate 25-g test portions of ISP, the test material was inoculated using Salmonella enterica subsp. enterica serovar Mbandaka (Q Laboratories isolate 11031.1). Salmonella enterica subsp. enterica serovar Tennessee (Q Laboratories isolate 11031.3) was used for all other trials. For each trial of the method comparison, 25 samples were analyzed for each matrix: 5 uninoculated controls and 20 samples inoculated at low levels (0.2 to 2 CFU per test portion) that were targeted to achieve fractionally positive results (25 to 75%). Using McNemar's chi-square analysis, no significant difference at P ≥ 0.05 (χ(2) ≤ 3.84) was observed between the number of positives obtained by the BAX System and the reference methods for all five test matrices evaluated. These studies indicate that the BAX System PCR assays, in combination with the single buffered peptone water primary enrichment and subsequent brain heart infusion regrowth step, demonstrate equivalent sensitivity and robustness compared with the FDA BAM and ISO reference methods for both 25- and 375-g composite samples. Moreover, there was no observed reduction of sensitivity in the larger 375-g composite samples for all five matrices.

Mechanical Property Evaluation of Palm/Glass Sandwiched Fiber Reinforced Polymer Composite in Comparison with few natural composites

NASA Astrophysics Data System (ADS)

Raja Dhas, J. Edwin; Pradeep, P.

2017-10-01

Natural fibers available plenty can be used as reinforcements in development of eco friendly polymer composites. The less utilized palm leaf stalk fibers sandwiched with artificial glass fibers was researched in this work to have a better reinforcement in preparing a green composite. The commercially available polyester resin blend with coconut shell filler in nano form was used as matrix to sandwich these composites. Naturally available Fibers of palm leaf stalk, coconut leaf stalk, raffia and oil palm were extracted and treated with potassium permanganate solution which enhances the properties. For experimentation four different plates were fabricated using these fibers adopting hand lay-up method. These sandwiched composite plates are further machined to obtain ASTM standards Specimens which are mechanically tested as per standards. Experimental results reveal that the alkali treated palm leaf stalk fiber based polymer composite shows appreciable results than the others. Hence the developed composite can be recommended for fabrication of automobile parts.

Progressive Failure And Life Prediction of Ceramic and Textile Composites

NASA Technical Reports Server (NTRS)

Xue, David Y.; Shi, Yucheng; Katikala, Madhu; Johnston, William M., Jr.; Card, Michael F.

1998-01-01

An engineering approach to predict the fatigue life and progressive failure of multilayered composite and textile laminates is presented. Analytical models which account for matrix cracking, statistical fiber failures and nonlinear stress-strain behavior have been developed for both composites and textiles. The analysis method is based on a combined micromechanics, fracture mechanics and failure statistics analysis. Experimentally derived empirical coefficients are used to account for the interface of fiber and matrix, fiber strength, and fiber-matrix stiffness reductions. Similar approaches were applied to textiles using Repeating Unit Cells. In composite fatigue analysis, Walker's equation is applied for matrix fatigue cracking and Heywood's formulation is used for fiber strength fatigue degradation. The analysis has been compared with experiment with good agreement. Comparisons were made with Graphite-Epoxy, C/SiC and Nicalon/CAS composite materials. For textile materials, comparisons were made with triaxial braided and plain weave materials under biaxial or uniaxial tension. Fatigue predictions were compared with test data obtained from plain weave C/SiC materials tested at AS&M. Computer codes were developed to perform the analysis. Composite Progressive Failure Analysis for Laminates is contained in the code CPFail. Micromechanics Analysis for Textile Composites is contained in the code MicroTex. Both codes were adapted to run as subroutines for the finite element code ABAQUS and CPFail-ABAQUS and MicroTex-ABAQUS. Graphic user interface (GUI) was developed to connect CPFail and MicroTex with ABAQUS.

Comparison of Shear Bond Strength of RMGI and Composite Resin for Orthodontic Bracket Bonding

PubMed Central

Yassaei, Soghra; Davari, Abdolrahim; Goldani Moghadam, Mahjobeh; Kamaei, Ahmad

2014-01-01

Objective: The aim of this study was to compare the shear bond strength (SBS) of resin modified glass ionomer (RMGI) and composite resin for bonding metal and ceramic brackets. Materials and Methods: Eighty-eight human premolars extracted for orthodontic purposes were divided into 4 groups (n=22). In groups 1 and 2, 22 metal and ceramic brackets were bonded using composite resin (Transbond XT), respectively. Twenty-two metal and ceramic brackets in groups 3 and 4, respectively were bonded using RMGI (Fuji Ortho LC, Japan). After photo polymerization, the teeth were stored in water and thermocycled (500 cycles between 5° and 55°). The SBS value of each sample was determined using a Universal Testing Machine. The amount of residual adhesive remaining on each tooth was evaluated under a stereomicroscope. Statistical analyses were done using two-way ANOVA. Results: RMGI bonded brackets had significantly lower SBS value compared to composite resin bonded groups. No statistically significant difference was observed between metal and ceramic brackets bonded with either the RMGI or composite resin. The comparison of the adhesive remnant index (ARI) scores between the groups indicated that the bracket failure mode was significantly different among groups (P<0.001) with more adhesive remaining on the teeth bonded with composite resin. Conclusion: RMGIs have significantly lower SBS compared to composite resin for orthodontic bonding purposes; however the provided SBS is still within the clinically acceptable range. PMID:25628663

Comparison of mechanical properties of multi-walled carbon nanotube and graphene nanosheet/polyethylene oxide composites plasticized with lithium triflate

NASA Astrophysics Data System (ADS)

Jurkane, A.; Gaidukov, S.

2017-10-01

A strong engineering interest in nanostructured conducting polymers and its composite materials have been widely used to build various sensor devices, electronic interconnect devices, fuel cells and batteries. Preparation of polymeric nano-composites with finely controlled structure, especially, at nano-scale, is still one of the most perspective modification ways of the properties of polymeric composites. Multi-walled carbon nanotube (MWCNT)/polyethylene oxide (PEO) and graphene nanosheets (GR)/PEO composites and composite of MWCNT/GR/PEO were prepared by solution casting and hot-pressing method. Composites were plasticized by 5% of Lithium triflate (LiTrifl), which play role of additional ion source in conducting polymer composite. Mechanical tensile tests were performed to evaluate nanoparticles influence on the mechanical strength of the conductive polymer composite materials. Difference of tensile tests of prepared composition can be seen from tensile tests data curves. The results of tensile tests indicated that the nanoparticles can provide PEO/5%LiTrifl composite with stiffening effects at rather low filler content (at least 0.05% by volume).

Temperature Distribution in a Composite of Opaque and Semitransparent Spectral Layers

NASA Technical Reports Server (NTRS)

Siegel, Robert

1997-01-01

The analysis of radiative transfer becomes computationally complex for a composite when there are multiple layers and multiple spectral bands. A convenient analytical method is developed for combined radiation and conduction in a composite of alternating semitransparent and opaque layers. The semi- transparent layers absorb, scatter, and emit radiation, and spectral properties with large scattering are included. The two-flux method is used, and its applicability is verified by comparison with a basic solution in the literature. The differential equation in the two-flux method Is solved by deriving a Green's function. The solution technique is applied to analyze radiation effects in a multilayer zirconia thermal barrier coating with internal radiation shields for conditions in an aircraft engine combustor. The zirconia radiative properties are modeled by two spectral bands. Thin opaque layers within the coating are used to decrease radiant transmission that can degrade the zirconia insulating ability. With radiation shields, the temperature distributions more closely approach the opaque limit that provides the lowest metal wall temperatures.

New perspectives in face correlation: discrimination enhancement in face recognition based on iterative algorithm

NASA Astrophysics Data System (ADS)

Wang, Q.; Alfalou, A.; Brosseau, C.

2016-04-01

Here, we report a brief review on the recent developments of correlation algorithms. Several implementation schemes and specific applications proposed in recent years are also given to illustrate powerful applications of these methods. Following a discussion and comparison of the implementation of these schemes, we believe that all-numerical implementation is the most practical choice for application of the correlation method because the advantages of optical processing cannot compensate the technical and/or financial cost needed for an optical implementation platform. We also present a simple iterative algorithm to optimize the training images of composite correlation filters. By making use of three or four iterations, the peak-to-correlation energy (PCE) value of correlation plane can be significantly enhanced. A simulation test using the Pointing Head Pose Image Database (PHPID) illustrates the effectiveness of this statement. Our method can be applied in many composite filters based on linear composition of training images as an optimization means.

Alignment-free genetic sequence comparisons: a review of recent approaches by word analysis.

PubMed

Bonham-Carter, Oliver; Steele, Joe; Bastola, Dhundy

2014-11-01

Modern sequencing and genome assembly technologies have provided a wealth of data, which will soon require an analysis by comparison for discovery. Sequence alignment, a fundamental task in bioinformatics research, may be used but with some caveats. Seminal techniques and methods from dynamic programming are proving ineffective for this work owing to their inherent computational expense when processing large amounts of sequence data. These methods are prone to giving misleading information because of genetic recombination, genetic shuffling and other inherent biological events. New approaches from information theory, frequency analysis and data compression are available and provide powerful alternatives to dynamic programming. These new methods are often preferred, as their algorithms are simpler and are not affected by synteny-related problems. In this review, we provide a detailed discussion of computational tools, which stem from alignment-free methods based on statistical analysis from word frequencies. We provide several clear examples to demonstrate applications and the interpretations over several different areas of alignment-free analysis such as base-base correlations, feature frequency profiles, compositional vectors, an improved string composition and the D2 statistic metric. Additionally, we provide detailed discussion and an example of analysis by Lempel-Ziv techniques from data compression. © The Author 2013. Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

The effect of erbium family laser on tensile bond strength of composite to dentin in comparison with conventional method.

PubMed

Shahabi, Sima; Chiniforush, Nasim; Bahramian, Hoda; Monzavi, Abbas; Baghalian, Ali; Kharazifard, Mohammad Javad

2013-01-01

The purpose of this study was to evaluate the effect of Er:YAG and Er,Cr:YSGG laser on tensile bond strength of composite resin to dentine in comparison with bur-prepared cavities. Fifteen extracted caries-free human third molars were selected. The teeth were cut at a level below the occlusal pit and fissure plan and randomly divided into three groups. Five cavities were prepared by diamond bur, five cavities prepared by Er:YAG laser, and the other group prepared by Er,Cr:YSGG laser. Then, all the cavities were restored by composite resin. The teeth were sectioned longitudinally with Isomet and the specimens prepared in dumbbelled shape (n = 36). The samples were attached to special jigs, and the tensile bond strength of the three groups was measured by universal testing machine at a speed of 0.5 mm/min. The results of the three groups were analyzed with one-way ANOVA and Tamhane test. The means and standard deviations of tensile bond strength of bur-cut, Er:YAG laser-ablated, and Er,Cr:YSGG laser-ablated dentine were 5.04 ± 0.93, 13.37 ± 3.87, and 4.85 ± 0.93 MPa, respectively. There is little difference in tensile bond strength of composite resin in Er,Cr:YSGG lased-prepared cavities in comparison with bur-prepared cavities, but the Er:YAG laser group showed higher bond strength than the other groups.

Comparison of humic substances isolated from peatbog water by sorption on DEAE-cellulose and amberlite XAD-2

USGS Publications Warehouse

Hejzlar, J.; Szpakowska, B.; Wershaw, R. L.

1994-01-01

Aquatic humic substances (AHS) were isolated from peatbog water by adsorption (1) on diethylaminoethyl cellulose (DEAE-C) and (2) on Amberlite XAD-2 (XAD) to compare yields of the methods and the composition of the isolated AHS. To provide a detailed comparison, the isolates were fractionated using size-exclusion and hydrophobic-interaction chromatography on Sephadex G-50. The fractions were characterized by ultraviolet-visible, infrared and 13C-nuclear magnetic spectroscopies and analyzed for elemental, functional-group, carbohydrate and amino acid compositions. More AHS adsorbed onto DEAE-C than onto XAD-2 (94 and 74%, respectively). However, only 76% of the AHS adsorbed onto DEAE-C was recovered using 0.1 M NaOH, whereas 98% of the AHS adsorbed onto XAD was released by consecutive elution with 1 M NH4OH (91%) and methanol (7%). Four main fractions of different composition were obtained from each of the alkali-desorbed AHS samples by Sephadex-gel chromatography. General agreement was found in relative amounts, spectroscopic characteristics and composition of corresponding fractions of both isolates except nitrogen content, which was significantly higher in AHS isolated with XAD, apparently due to the reaction of AHS with NH4OH used for the desorption from the resin.Aquatic humic substances (AHS) were isolated from peatbog water by adsorption (1) on diethylaminoethyl cellulose (DEAE-C) and (2) on Amberlite XAD-2 (XAD) to compare yields of the methods and the composition of the isolated AHS. To provide a detailed comparison, the isolates were fractionated using size-exclusion and hydrophobic-interaction chromatography on Sephadex G-50. The fractions were characterized by ultraviolet-visible, infrared and 13C-nuclear magnetic spectroscopies and analyzed for elemental, functional-group, carbohydrate and amino acid compositions. More AHS adsorbed onto DEAE-C than onto XAD-2 (94 and 74%, respectively). However, only 76% of the AHS adsorbed onto DEAE-C was recovered using 0.1 M NaOH, whereas 98% of the AHS adsorbed onto XAD was released by consecutive elution with 1 M NH4OH (91%) and methanol (7%). Four main fractions of different composition were obtained from each of the alkali-desorbed AHS samples by Sephadex-gel chromatography. General agreement was found in relative amounts, spectroscopic characteristics and composition of corresponding fractions of both isolates except nitrogen content, which was significantly higher in AHS isolated with XAD, apparently due to the reaction of AHS with NH4OH used for the desorption from the resin.

A comparison of locally adaptive multigrid methods: LDC, FAC and FIC

NASA Technical Reports Server (NTRS)

Khadra, Khodor; Angot, Philippe; Caltagirone, Jean-Paul

1993-01-01

This study is devoted to a comparative analysis of three 'Adaptive ZOOM' (ZOom Overlapping Multi-level) methods based on similar concepts of hierarchical multigrid local refinement: LDC (Local Defect Correction), FAC (Fast Adaptive Composite), and FIC (Flux Interface Correction)--which we proposed recently. These methods are tested on two examples of a bidimensional elliptic problem. We compare, for V-cycle procedures, the asymptotic evolution of the global error evaluated by discrete norms, the corresponding local errors, and the convergence rates of these algorithms.

Detection of delamination defects in CFRP materials using ultrasonic signal processing.

PubMed

Benammar, Abdessalem; Drai, Redouane; Guessoum, Abderrezak

2008-12-01

In this paper, signal processing techniques are tested for their ability to resolve echoes associated with delaminations in carbon fiber-reinforced polymer multi-layered composite materials (CFRP) detected by ultrasonic methods. These methods include split spectrum processing (SSP) and the expectation-maximization (EM) algorithm. A simulation study on defect detection was performed, and results were validated experimentally on CFRP with and without delamination defects taken from aircraft. Comparison of the methods for their ability to resolve echoes are made.

Dietary Compositions and Their Seasonal Shifts in Japanese Resident Birds, Estimated from the Analysis of Volunteer Monitoring Data

PubMed Central

Yoshikawa, Tetsuro; Osada, Yutaka

2015-01-01

Determining the composition of a bird’s diet and its seasonal shifts are fundamental for understanding the ecology and ecological functions of a species. Various methods have been used to estimate the dietary compositions of birds, which have their own advantages and disadvantages. In this study, we examined the possibility of using long-term volunteer monitoring data as the source of dietary information for 15 resident bird species in Kanagawa Prefecture, Japan. The data were collected from field observations reported by volunteers of regional naturalist groups. Based on these monitoring data, we calculated the monthly dietary composition of each bird species directly, and we also estimated unidentified items within the reported foraging episodes using Bayesian models that contained additional information regarding foraging locations. Next, to examine the validity of the estimated dietary compositions, we compared them with the dietary information for focal birds based on stomach analysis methods, collected from past literatures. The dietary trends estimated from the monitoring data were largely consistent with the general food habits determined from the previous studies of focal birds. Thus, the estimates based on the volunteer monitoring data successfully detected noticeable seasonal shifts in many of the birds from plant materials to animal diets during spring—summer. Comparisons with stomach analysis data supported the qualitative validity of the monitoring-based dietary information and the effectiveness of the Bayesian models for improving the estimates. This comparison suggests that one advantage of using monitoring data is its ability to detect dietary items such as fleshy fruits, flower nectar, and vertebrates. These results emphasize the potential importance of observation data collecting and mining by citizens, especially free descriptive observation data, for use in bird ecology studies. PMID:25723544

A fractal image analysis methodology for heat damage inspection in carbon fiber reinforced composites

NASA Astrophysics Data System (ADS)

Haridas, Aswin; Crivoi, Alexandru; Prabhathan, P.; Chan, Kelvin; Murukeshan, V. M.

2017-06-01

The use of carbon fiber-reinforced polymer (CFRP) composite materials in the aerospace industry have far improved the load carrying properties and the design flexibility of aircraft structures. A high strength to weight ratio, low thermal conductivity, and a low thermal expansion coefficient gives it an edge for applications demanding stringent loading conditions. Specifically, this paper focuses on the behavior of CFRP composites under stringent thermal loads. The properties of composites are largely affected by external thermal loads, especially when the loads are beyond the glass temperature, Tg, of the composite. Beyond this, the composites are subject to prominent changes in mechanical and thermal properties which may further lead to material decomposition. Furthermore, thermal damage formation being chaotic, a strict dimension cannot be associated with the formed damage. In this context, this paper focuses on comparing multiple speckle image analysis algorithms to effectively characterize the formed thermal damages on the CFRP specimen. This would provide us with a fast method for quantifying the extent of heat damage in carbon composites, thus reducing the required time for inspection. The image analysis methods used for the comparison include fractal dimensional analysis of the formed speckle pattern and analysis of number and size of various connecting elements in the binary image.

Total milk fat extraction and quantification of polar and neutral lipids of cow, goat, and ewe milk by using a pressurized liquid system and chromatographic techniques.

PubMed

Castro-Gómez, M P; Rodriguez-Alcalá, L M; Calvo, M V; Romero, J; Mendiola, J A; Ibañez, E; Fontecha, J

2014-11-01

Although milk polar lipids such as phospholipids and sphingolipids located in the milk fat globule membrane constitute 0.1 to 1% of the total milk fat, those lipid fractions are gaining increasing interest because of their potential beneficial effects on human health and technological properties. In this context, the accurate quantification of the milk polar lipids is crucial for comparison of different milk species, products, or dairy treatments. Although the official International Organization for Standardization-International Dairy Federation method for milk lipid extraction gives satisfactory results for neutral lipids, it has important disadvantages in terms of polar lipid losses. Other methods using mixtures of solvents such as chloroform:methanol are highly efficient for extracting polar lipids but are also associated with low sample throughput, long time, and large solvent consumption. As an alternative, we have optimized the milk fat extraction yield by using a pressurized liquid extraction (PLE) method at different temperatures and times in comparison with those traditional lipid extraction procedures using 2:1 chloroform:methanol as a mixture of solvents. Comparison of classical extraction methods with the developed PLE procedure were carried out using raw whole milk from different species (cows, ewes, and goats) and considering fat yield, fatty acid methyl ester composition, triacylglyceride species, cholesterol content, and lipid class compositions, with special attention to polar lipids such as phospholipids and sphingolipids. The developed PLE procedure was validated for milk fat extraction and the results show that this method performs a complete or close to complete extraction of all lipid classes and in less time than the official and Folch methods. In conclusion, the PLE method optimized in this study could be an alternative to carry out milk fat extraction as a routine method. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Thermal and mechanical behavior of metal matrix and ceramic matrix composites

NASA Technical Reports Server (NTRS)

Kennedy, John M. (Editor); Moeller, Helen H. (Editor); Johnson, W. S. (Editor)

1990-01-01

The present conference discusses local stresses in metal-matrix composites (MMCs) subjected to thermal and mechanical loads, the computational simulation of high-temperature MMCs' cyclic behavior, an analysis of a ceramic-matrix composite (CMC) flexure specimen, and a plasticity analysis of fibrous composite laminates under thermomechanical loads. Also discussed are a comparison of methods for determining the fiber-matrix interface frictional stresses of CMCs, the monotonic and cyclic behavior of an SiC/calcium aluminosilicate CMC, the mechanical and thermal properties of an SiC particle-reinforced Al alloy MMC, the temperature-dependent tensile and shear response of a graphite-reinforced 6061 Al-alloy MMC, the fiber/matrix interface bonding strength of MMCs, and fatigue crack growth in an Al2O3 short fiber-reinforced Al-2Mg matrix MMC.

Failure Rate of Direct High-Viscosity Glass-Ionomer Versus Hybrid Resin Composite Restorations in Posterior Permanent Teeth - a Systematic Review

PubMed Central

Mickenautsch, Steffen; Yengopal, Veerasamy

2015-01-01

Purpose Traditionally, resin composite restorations are claimed by reviews of the dental literature as being superior to glass-ionomer fillings in terms of restoration failures in posterior permanent teeth. The aim of this systematic review is to answer the clinical question, whether conventional high-viscosity glass-ionomer restorations, in patients with single and/or multi-surface cavities in posterior permanent teeth, have indeed a higher failure rate than direct hybrid resin composite restorations. Methods Eight databases were searched until December 02, 2013. Trials were assessed for bias risks, in-between datasets heterogeneity and statistical sample size power. Effects sizes were computed and statistically compared. A total of 55 citations were identified through systematic literature search. From these, 46 were excluded. No trials related to high-viscosity glass-ionomers versus resin composite restorations for direct head-to-head comparison were found. Three trials related to high-viscosity glass-ionomers versus amalgam and three trials related to resin composite versus amalgam restorations could be included for adjusted indirect comparison, only. Results The available evidence suggests no difference in the failure rates between both types of restoration beyond the play of chance, is limited by lack of head-to-head comparisons and an insufficient number of trials, as well as by high bias and in-between-dataset heterogeneity risk. The current clinical evidence needs to be regarded as too poor in order to justify superiority claims regarding the failure rates of both restoration types. Sufficiently large-sized, parallel-group, randomised control trials with high internal validity are needed, in order to justify any clinically meaningful judgment to this topic. PMID:26962372

Mechanical and thermal properties and morphological studies of 10 MeV electron beam irradiated LDPE/hydroxyapatite nano-composite

NASA Astrophysics Data System (ADS)

Soltani, Z.; Ziaie, F.; Ghaffari, M.; Afarideh, H.; Ehsani, M.

2013-02-01

In this work the nano-composite samples were prepared using the LDPE filled with different weight percentages of hydroxyapatite powder which was synthesized via hydrolysis method. The samples were subjected to irradiation under 10 MeV electron beam in 75-250 kGy doses. Mechanical and thermal properties as well as the morphology of the nano-composite samples were investigated and compared. The hot-set and swelling tests confirmed the radiation crosslinking induced in the polymer matrix especially between the matrix and reinforcement phase. The result indicates that the mechanical and thermal parameters are strongly dependent on the hydroxyapatite content in comparison to radiation.

Thermal Inspection of Composite Honeycomb Structures

NASA Technical Reports Server (NTRS)

Zalameda, Joseph N.; Parker, F. Raymond

2014-01-01

Composite honeycomb structures continue to be widely used in aerospace applications due to their low weight and high strength advantages. Developing nondestructive evaluation (NDE) inspection methods are essential for their safe performance. Pulsed thermography is a commonly used technique for composite honeycomb structure inspections due to its large area and rapid inspection capability. Pulsed thermography is shown to be sensitive for detection of face sheet impact damage and face sheet to core disbond. Data processing techniques, using principal component analysis to improve the defect contrast, are presented. In addition, limitations to the thermal detection of the core are investigated. Other NDE techniques, such as computed tomography X-ray and ultrasound, are used for comparison to the thermography results.

Effect of finishing and polishing procedures on surface roughness, gloss and color of resin-based composites.

PubMed

Paravina, Rade D; Roeder, Leslie; Lu, Huan; Vogel, Karin; Powers, John M

2004-08-01

To evaluate the effects of different finishing and polishing procedures on surface roughness, gloss and color of five resin composites: two experimental microhybrid composites - FZ-Dentin (FZD) and FZ-Enamel (FZE), one commercial microhybrid composite - Esthet-X (EX), and two microfilled composites - Heliomolar (HM) and Renamel Microfill (RM). Surface roughness, gloss and color of the disc-shaped specimens (10 mm in diameter and 2-mm thick) were measured as Mylar (baseline), 16-fluted carbide bur and polishing were completed. Sixteen specimens of each composite were randomized to four groups of four. After finishing with a 16-fluted finishing bur, each group was polished by a different system: 1. Astropol (A), 2. Sof-lex disc (S), 3. Po-Go (P), 4. Enhance (E). Average surface roughness (Ra) was measured with a profilometer. Gloss measurements were performed using small-area glossmeter, while color coordinate values were recorded using a spectrophotometer. A deltaE*ab< or =1 was considered to be the limit of perceptibility. The order of surface roughness ranked according to polishing system (for all five composites together) was: P < S < E < A. The order of surface roughness ranked according to composites was: RM < FZD < FZ < HM < EX. The order of gloss ranked according to polishing system (for all five composites together) was: P > E > A > S. The order of gloss values for the polished composites (for each of four polishing systems) was: RM > FZD > FZE > HM > EX. Fisher's PLSD intervals at the 0.05 level of significance for comparisons of means of surface roughness among five composites and four polishing systems were 0.01 and 0.01 microm, respectively. Fisher's PLSD intervals at the 0.05 level of significance for comparisons of means of gloss among five composites and four polishing systems were 6 and 5 GU, respectively. Color differences (deltaE*ab) among five composites and four polishing methods were found to range from 0.2 to 1.1.

Comparison of two methods for composite score generation in dry eye syndrome.

PubMed

See, Craig; Bilonick, Richard A; Feuer, William; Galor, Anat

2013-09-19

To compare two methods of composite score generation in dry eye syndrome (DES). Male patients seen in the Miami Veterans Affairs eye clinic with normal eyelid, corneal, and conjunctival anatomy were recruited to participate in the study. Patients filled out the Dry Eye Questionnaire 5 (DEQ5) and underwent measurement of tear film parameters. DES severity scores were generated by independent component analysis (ICA) and latent class analysis (LCA). A total of 247 men were included in the study. Mean age was 69 years (SD 9). Using ICA analysis, osmolarity was found to carry the largest weight, followed by eyelid vascularity and meibomian orifice plugging. Conjunctival injection and tear breakup time (TBUT) carried the lowest weights. Using LCA analysis, TBUT was found to be best at discriminating healthy from diseased eyes, followed closely by Schirmer's test. DEQ5, eyelid vascularity, and conjunctival injection were the poorest at discrimination. The adjusted correlation coefficient between the two generated composite scores was 0.63, indicating that the shared variance was less than 40%. Both ICA and LCA produced composite scores for dry eye severity, with weak to moderate agreement; however, agreement for the relative importance of single diagnostic tests was poor between the two methods.

Program CONTRAST--A general program for the analysis of several survival or recovery rate estimates

USGS Publications Warehouse

Hines, J.E.; Sauer, J.R.

1989-01-01

This manual describes the use of program CONTRAST, which implements a generalized procedure for the comparison of several rate estimates. This method can be used to test both simple and composite hypotheses about rate estimates, and we discuss its application to multiple comparisons of survival rate estimates. Several examples of the use of program CONTRAST are presented. Program CONTRAST will run on IBM-cimpatible computers, and requires estimates of the rates to be tested, along with associated variance and covariance estimates.

Alignment of Boron Nitride Nanofibers in Epoxy Composite Films for Thermal Conductivity and Dielectric Breakdown Strength Improvement.

PubMed

Wang, Zhengdong; Liu, Jingya; Cheng, Yonghong; Chen, Siyu; Yang, Mengmeng; Huang, Jialiang; Wang, Hongkang; Wu, Guanglei; Wu, Hongjing

2018-04-15

Development of polymer-based composites with simultaneously high thermal conductivity and breakdown strength has attracted considerable attention owing to their important applications in both electronic and electric industries. In this work, boron nitride (BN) nanofibers (BNNF) are successfully prepared as fillers, which are used for epoxy composites. In addition, the BNNF in epoxy composites are aligned by using a film casting method. The composites show enhanced thermal conductivity and dielectric breakdown strength. For instance, after doping with BNNF of 2 wt%, the thermal conductivity of composites increased by 36.4% in comparison with that of the epoxy matrix. Meanwhile, the breakdown strength of the composite with 1 wt% BNNF is 122.9 kV/mm, which increased by 6.8% more than that of neat epoxy (115.1 kV/mm). Moreover, the composites have maintained a low dielectric constant and alternating current conductivity among the range of full frequency, and show a higher thermal decomposition temperature and glass-transition temperature. The composites with aligning BNNF have wide application prospects in electronic packaging material and printed circuit boards.

Alignment of Boron Nitride Nanofibers in Epoxy Composite Films for Thermal Conductivity and Dielectric Breakdown Strength Improvement

PubMed Central

Liu, Jingya; Cheng, Yonghong; Chen, Siyu; Yang, Mengmeng; Huang, Jialiang

2018-01-01

Development of polymer-based composites with simultaneously high thermal conductivity and breakdown strength has attracted considerable attention owing to their important applications in both electronic and electric industries. In this work, boron nitride (BN) nanofibers (BNNF) are successfully prepared as fillers, which are used for epoxy composites. In addition, the BNNF in epoxy composites are aligned by using a film casting method. The composites show enhanced thermal conductivity and dielectric breakdown strength. For instance, after doping with BNNF of 2 wt%, the thermal conductivity of composites increased by 36.4% in comparison with that of the epoxy matrix. Meanwhile, the breakdown strength of the composite with 1 wt% BNNF is 122.9 kV/mm, which increased by 6.8% more than that of neat epoxy (115.1 kV/mm). Moreover, the composites have maintained a low dielectric constant and alternating current conductivity among the range of full frequency, and show a higher thermal decomposition temperature and glass-transition temperature. The composites with aligning BNNF have wide application prospects in electronic packaging material and printed circuit boards. PMID:29662038

Sustained prediction ability of net analyte preprocessing methods using reduced calibration sets. Theoretical and experimental study involving the spectrophotometric analysis of multicomponent mixtures.

PubMed

Goicoechea, H C; Olivieri, A C

2001-07-01

A newly developed multivariate method involving net analyte preprocessing (NAP) was tested using central composite calibration designs of progressively decreasing size regarding the multivariate simultaneous spectrophotometric determination of three active components (phenylephrine, diphenhydramine and naphazoline) and one excipient (methylparaben) in nasal solutions. Its performance was evaluated and compared with that of partial least-squares (PLS-1). Minimisation of the calibration predicted error sum of squares (PRESS) as a function of a moving spectral window helped to select appropriate working spectral ranges for both methods. The comparison of NAP and PLS results was carried out using two tests: (1) the elliptical joint confidence region for the slope and intercept of a predicted versus actual concentrations plot for a large validation set of samples and (2) the D-optimality criterion concerning the information content of the calibration data matrix. Extensive simulations and experimental validation showed that, unlike PLS, the NAP method is able to furnish highly satisfactory results when the calibration set is reduced from a full four-component central composite to a fractional central composite, as expected from the modelling requirements of net analyte based methods.

Comparison of SOC estimates and uncertainties from aerosol chemical composition and gas phase data in Atlanta

NASA Astrophysics Data System (ADS)

Pachon, Jorge E.; Balachandran, Sivaraman; Hu, Yongtao; Weber, Rodney J.; Mulholland, James A.; Russell, Armistead G.

2010-10-01

In the Southeastern US, organic carbon (OC) comprises about 30% of the PM 2.5 mass. A large fraction of OC is estimated to be of secondary origin. Long-term estimates of SOC and uncertainties are necessary in the evaluation of air quality policy effectiveness and epidemiologic studies. Four methods to estimate secondary organic carbon (SOC) and respective uncertainties are compared utilizing PM 2.5 chemical composition and gas phase data available in Atlanta from 1999 to 2007. The elemental carbon (EC) tracer and the regression methods, which rely on the use of tracer species of primary and secondary OC formation, provided intermediate estimates of SOC as 30% of OC. The other two methods, chemical mass balance (CMB) and positive matrix factorization (PMF) solve mass balance equations to estimate primary and secondary fractions based on source profiles and statistically-derived common factors, respectively. CMB had the highest estimate of SOC (46% of OC) while PMF led to the lowest (26% of OC). The comparison of SOC uncertainties, estimated based on propagation of errors, led to the regression method having the lowest uncertainty among the four methods. We compared the estimates with the water soluble fraction of the OC, which has been suggested as a surrogate of SOC when biomass burning is negligible, and found a similar trend with SOC estimates from the regression method. The regression method also showed the strongest correlation with daily SOC estimates from CMB using molecular markers. The regression method shows advantages over the other methods in the calculation of a long-term series of SOC estimates.

Statistical tables and charts showing geochemical variation in the Mesoproterozoic Big Creek, Apple Creek, and Gunsight formations, Lemhi group, Salmon River Mountains and Lemhi Range, central Idaho

USGS Publications Warehouse

Lindsey, David A.; Tysdal, Russell G.; Taggart, Joseph E.

2002-01-01

The principal purpose of this report is to provide a reference archive for results of a statistical analysis of geochemical data for metasedimentary rocks of Mesoproterozoic age of the Salmon River Mountains and Lemhi Range, central Idaho. Descriptions of geochemical data sets, statistical methods, rationale for interpretations, and references to the literature are provided. Three methods of analysis are used: R-mode factor analysis of major oxide and trace element data for identifying petrochemical processes, analysis of variance for effects of rock type and stratigraphic position on chemical composition, and major-oxide ratio plots for comparison with the chemical composition of common clastic sedimentary rocks.

Thermal stable superhydrophobic polyphenylsilsesquioxane/nanosilica composite coatings

NASA Astrophysics Data System (ADS)

Yang, Haowei; Cheng, Yuanrong; Xiao, Fei

2011-12-01

The superhydrophobic polyphenylsilsesquioxane (PPSQ)/nanosilica composite coatings were prepared by spray coating method with nano fumed silica (NFS) particles embedded in PPSQ matrix. The water contact angle (WCA) increased from 92.9° to 152.5° and the sliding angle (SA) decreased from more than 60° to 3.9° as the NFS content increased. The superhydrophobicity retained up to 500 °C, sustained by the hierarchical micro-nano structures and excellent thermal stability of PPSQ. A superhydrophobic PPSQ coating with WCA of 152.6° and SA of 7.8° was obtained by solvent-nonsolvent method for comparison as well. However, it gradually lost superhydrophobicity at 200 °C because of the elimination of nanostructures by the thermal softening of PPSQ.

Comparison of measured and calculated composition of irradiated EBR-II blanket assemblies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grimm, K. N.

1998-07-13

In anticipation of processing irradiated EBR-II depleted uranium blanket subassemblies in the Fuel Conditioning Facility (FCF) at ANL-West, it has been possible to obtain a limited set of destructive chemical analyses of samples from a single EBR-II blanket subassembly. Comparison of calculated values with these measurements is being used to validate a depletion methodology based on a limited number of generic models of EBR-II to simulate the irradiation history of these subassemblies. Initial comparisons indicate these methods are adequate to meet the operations and material control and accountancy (MC and A) requirements for the FCF, but also indicate several shortcomingsmore » which may be corrected or improved.« less

Advanced Image Processing for Defect Visualization in Infrared Thermography

NASA Technical Reports Server (NTRS)

Plotnikov, Yuri A.; Winfree, William P.

1997-01-01

Results of a defect visualization process based on pulse infrared thermography are presented. Algorithms have been developed to reduce the amount of operator participation required in the process of interpreting thermographic images. The algorithms determine the defect's depth and size from the temporal and spatial thermal distributions that exist on the surface of the investigated object following thermal excitation. A comparison of the results from thermal contrast, time derivative, and phase analysis methods for defect visualization are presented. These comparisons are based on three dimensional simulations of a test case representing a plate with multiple delaminations. Comparisons are also based on experimental data obtained from a specimen with flat bottom holes and a composite panel with delaminations.

Quantitative comparison of tumor delivery for multiple targeted nanoparticles simultaneously by multiplex ICP-MS.

PubMed

Elias, Andrew; Crayton, Samuel H; Warden-Rothman, Robert; Tsourkas, Andrew

2014-07-28

Given the rapidly expanding library of disease biomarkers and targeting agents, the number of unique targeted nanoparticles is growing exponentially. The high variability and expense of animal testing often makes it unfeasible to examine this large number of nanoparticles in vivo. This often leads to the investigation of a single formulation that performed best in vitro. However, nanoparticle performance in vivo depends on many variables, many of which cannot be adequately assessed with cell-based assays. To address this issue, we developed a lanthanide-doped nanoparticle method that allows quantitative comparison of multiple targeted nanoparticles simultaneously. Specifically, superparamagnetic iron oxide (SPIO) nanoparticles with different targeting ligands were created, each with a unique lanthanide dopant. Following the simultaneous injection of the various SPIO compositions into tumor-bearing mice, inductively coupled plasma mass spectroscopy was used to quantitatively and orthogonally assess the concentration of each SPIO composition in serial blood and resected tumor samples.

A comprehensive NMR methodology to assess the composition of biobased and biodegradable polymers in contact with food.

PubMed

Gratia, Audrey; Merlet, Denis; Ducruet, Violette; Lyathaud, Cédric

2015-01-01

A nuclear magnetic resonance (NMR) methodology was assessed regarding the identification and quantification of additives in three types of polylactide (PLA) intended as food contact materials. Additives were identified using the LNE/NMR database which clusters NMR datasets on more than 130 substances authorized by European Regulation No. 10/2011. Of the 12 additives spiked in the three types of PLA pellets, 10 were rapidly identified by the database and correlated with spectral comparison. The levels of the 12 additives were estimated using quantitative NMR combined with graphical computation. A comparison with chromatographic methods tended to prove the sensitivity of NMR by demonstrating an analytical difference of less than 15%. Our results therefore demonstrated the efficiency of the proposed NMR methodology for rapid assessment of the composition of PLA. Copyright © 2014 Elsevier B.V. All rights reserved.

In vitro caries-inhibitory properties of a silver cermet.

PubMed

Swift, E J

1989-06-01

Recurrent caries is one of the primary causes of failure of dental restorations. One method for reducing the frequency and severity of this problem is the use of fluoride-releasing restorative materials. The glass-ionomer cements are a type of fluoride-releasing material. They have been used extensively in recent years for a variety of clinical applications. However, in comparison with other restorative materials such as amalgam and composite resins, glass ionomers have relatively poor physical properties. Sintering of silver particles to glass-ionomer powder is a means of improving these physical properties. The sintered material is called a silver-glass ionomer or silver cermet. This study examined the in vitro caries-inhibitory potential of a silver cement by means of two methods. First, long-term fluoride release was measured. Second, an artificial caries system was used for evaluation of caries inhibition by cerment restorations in extracted teeth. In comparison with a standard glass-ionomer restorative material, fluoride release from the cermet material was significantly less throughout a 12-month period. The results from the artificial caries system indicated that this decreased fluoride release corresponded with a lesser degree of caries inhibition. Lesions around cermet restorations in both enamel and root surfaces were significantly more severe than those around conventional glass-ionomer restorations. However, in comparison with amalgam and composite resin restorations, the cermet did have some cariostatic activity.

Comparison of some effects of modification of a polylactide surface layer by chemical, plasma, and laser methods

NASA Astrophysics Data System (ADS)

Moraczewski, Krzysztof; Rytlewski, Piotr; Malinowski, Rafał; Żenkiewicz, Marian

2015-08-01

The article presents the results of studies and comparison of selected properties of the modified PLA surface layer. The modification was carried out with three methods. In the chemical method, a 0.25 M solution of sodium hydroxide in water and ethanol was utilized. In the plasma method, a 50 W generator was used, which produced plasma in the air atmosphere under reduced pressure. In the laser method, a pulsed ArF excimer laser with fluency of 60 mJ/cm2 was applied. Polylactide samples were examined by using the following techniques: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and X-ray photoelectron spectroscopy (XPS). Images of surfaces of the modified samples were recorded, contact angles were measured, and surface free energy was calculated. Qualitative and quantitative analyses of chemical composition of the PLA surface layer were performed as well. Based on the survey it was found that the best modification results are obtained using the plasma method.

[Free crystalline silica: a comparison of methods for its determination in total dust].

PubMed

Maciejewska, Aleksandra; Szadkowska-Stańczyk, Irena; Kondratowicz, Grzegorz

2005-01-01

The major objective of the study was to compare and investigate the usefulness of quantitative analyses of free crystalline silica (FCS) in the assessment of dust exposure in samples of total dust of varied composition, using three methods: chemical method in common use in Poland; infrared spectrometry; and x-ray powder diffraction. Mineral composition and FCS contents were investigated in 9 laboratory samples of raw materials, materials, and industrial wastes, containing from about 2 to over 80% of crystalline silica and reduced to particles of size corresponding with that of total dust. Sample components were identified using XRD and FT-IR methods. Ten independent determinations of FCS with each of the three study methods were performed in dust samples. An analysis of linear correlation was applied to investigate interrelationship between mean FCS determinations. In analyzed dust samples, along with silica dust there were numerous minerals interfering with silica during the quantitative analysis. Comparison of mean results of FCS determinations showed that the results obtained using the FT-IR method were by 12-13% lower than those obtained with two other methods. However, the differences observed were within the limits of changeability of results associated with their precision and dependence on reference materials used. Assessment of occupational exposure to dusts containing crystalline silica can be performed on the basis of quantitative analysis of FCS in total dusts using each of the compared methods. The FT-IR method is most appropriate for the FCS determination in samples of small amount of silica or collected at low dust concentrations; the XRD method for the analysis of multicomponent samples; and the chemical method in the case of medium and high FCS contents in samples or high concentrations of dusts in the work environment.

Changes in the phenolic composition of pancake fractions made from refined and whole-wheat flour of two wheat varieties

USDA-ARS?s Scientific Manuscript database

In this study, we investigated the changes in the levels of phenolic acids during pancake preparation from refined and whole-wheat flours of two wheat varieties. Comparison of the efficacy of two commonly used methods for hydrolysis and extraction of phenolic acids, namely ultrasonic-assisted extrac...

Comparison of TiO2 nanoparticle and graphene-TiO2 nanoparticle composite phototoxicity to Daphnia magna and Oryzias latipes

EPA Science Inventory

With a dramatic rise in complexity, needs of nanotoxicology research go beyond simple forms of nanomaterials. This study compared the phototoxicity of nano-TiO2and graphene-TiO2 nanocomposite (GNP). GNP was synthesized based on a hydrothermal method, which simultaneously performe...

Dual-functional composite with anticoagulant and antibacterial properties based on heparinized silk fibroin and chitosan.

PubMed

Wang, Jianglin; Hu, Wei; Liu, Qun; Zhang, Shengmin

2011-07-01

Heparinized biomaterials exhibit great anticoagulant properties. However, they promote proliferation of Staphylococcus aureus (S. aureus) and therefore cause infection within the bloodstream upon implantation in vivo. In the present study, an interesting dual-functional composite with anticoagulant and antibacterial properties based on heparinized silk fibroin and chitosan was synthesized. First, heparin was grafted onto the silk fibroin by covalent immobilization with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS). All data gathered from Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and elemental analysis (EA) indicated that the heparin was successfully immobilized onto the silk fibroin. The dual-functional composite of heparinized silk fibroin and chitosan was then fabricated by a blending method. The anticoagulant activity of the heparinized materials was evaluated using the prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT). The results showed that both heparinized silk fibroin and the composite material exhibited better hemocompatibility in comparison with single silk fibroin or chitosan. The antibacterial property of the materials was investigated by the pour-plate method. Results further suggested that the composite antibacterial property with respect to S. aureus was significantly enhanced. The dual-functionality of the composite material may supply a potential choice in blood contact devices. Copyright © 2011 Elsevier B.V. All rights reserved.

Investigation of Fiber Waviness in a Thick Glass Composite Beam Using THz NDE

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.

2008-01-01

Fiber waviness in laminated composite material is introduced during manufacture because of uneven curing, resin shrinkage, or ply buckling caused by bending the composite lay-up into its final shape prior to curing. The resulting waviness has a detrimental effect on mechanical properties, therefore this condition is important to detect and characterize. Ultrasonic characterization methods are difficult to interpret because elastic wave propagation is highly dependent on ply orientation and material stresses. By comparison, the pulsed terahertz response of the composite is shown to provide clear indications of the fiber waviness. Pulsed Terahertz NDE is an electromagnetic inspection method that operates in the frequency range between 300 GHz and 3 THz. Its propagation is influenced by refractive index variations and interfaces. This work applies pulsed Terahertz NDE to the inspection of a thick composite beam with fiber waviness. The sample is a laminated glass composite material approximately 15mm thick with a 90-degree bend. Terahertz response from the planar section, away from the bend, is indicative of a homogeneous material with no major reflections from internal plies, while the multiple reflections at the bend area correspond to the fiber waviness. Results of these measurements are presented for the planar and bend areas.

A 3T Sodium and Proton Composite Array Breast Coil

PubMed Central

Kaggie, Joshua D.; Hadley, J. Rock; Badal, James; Campbell, John R.; Park, Daniel J.; Parker, Dennis L.; Morrell, Glen; Newbould, Rexford D.; Wood, Ali F.; Bangerter, Neal K.

2013-01-01

Purpose The objective of this study was to determine whether a sodium phased array would improve sodium breast MRI at 3T. The secondary objective was to create acceptable proton images with the sodium phased array in place. Methods A novel composite array for combined proton/sodium 3T breast MRI is compared to a coil with a single proton and sodium channel. The composite array consists of a 7-channel sodium receive array, a larger sodium transmit coil, and a 4-channel proton transceive array. The new composite array design utilizes smaller sodium receive loops than typically used in sodium imaging, uses novel decoupling methods between the receive loops and transmit loops, and uses a novel multi-channel proton transceive coil. The proton transceive coil reduces coupling between proton and sodium elements by intersecting the constituent loops to reduce their mutual inductance. The coil used for comparison consists of a concentric sodium and proton loop with passive decoupling traps. Results The composite array coil demonstrates a 2–5x improvement in SNR for sodium imaging and similar SNR for proton imaging when compared to a simple single-loop dual resonant design. Conclusion The improved SNR of the composite array gives breast sodium images of unprecedented quality in reasonable scan times. PMID:24105740

FY16 Annual Accomplishments - Waste Form Development and Performance: Evaluation Of Ceramic Waste Forms - Comparison Of Hot Isostatic Pressed And Melt Processed Fabrication Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amoroso, J.; Dandeneau, C.

FY16 efforts were focused on direct comparison of multi-phase ceramic waste forms produced via melt processing and HIP methods. Based on promising waste form compositions previously devised at SRNL, simulant material was prepared at SRNL and a portion was sent to the Australian Nuclear Science and Technology Organization (ANSTO) for HIP treatments, while the remainder of the material was melt processed at SRNL. The microstructure, phase formation, elemental speciation, and leach behavior, and radiation stability of the fabricated ceramics was performed. In addition, melt-processed ceramics designed with different fractions of hollandite, zirconolite, perovskite, and pyrochlore phases were investigated. for performancemore » and properties.« less

Local Discontinuous Galerkin (LDG) Method for Advection of Active Compositional Fields with Discontinuous Boundaries: Demonstration and Comparison with Other Methods in the Mantle Convection Code ASPECT

NASA Astrophysics Data System (ADS)

He, Y.; Billen, M. I.; Puckett, E. G.

2015-12-01

Flow in the Earth's mantle is driven by thermo-chemical convection in which the properties and geochemical signatures of rocks vary depending on their origin and composition. For example, tectonic plates are composed of compositionally-distinct layers of crust, residual lithosphere and fertile mantle, while in the lower-most mantle there are large compositionally distinct "piles" with thinner lenses of different material. Therefore, tracking of active or passive fields with distinct compositional, geochemical or rheologic properties is important for incorporating physical realism into mantle convection simulations, and for investigating the long term mixing properties of the mantle. The difficulty in numerically advecting fields arises because they are non-diffusive and have sharp boundaries, and therefore require different methods than usually used for temperature. Previous methods for tracking fields include the marker-chain, tracer particle, and field-correction (e.g., the Lenardic Filter) methods: each of these has different advantages or disadvantages, trading off computational speed with accuracy in tracking feature boundaries. Here we present a method for modeling active fields in mantle dynamics simulations using a new solver implemented in the deal.II package that underlies the ASPECT software. The new solver for the advection-diffusion equation uses a Local Discontinuous Galerkin (LDG) algorithm, which combines features of both finite element and finite volume methods, and is particularly suitable for problems with a dominant first-order term and discontinuities. Furthermore, we have applied a post-processing technique to insure that the solution satisfies a global maximum/minimum. One potential drawback for the LDG method is that the total number of degrees of freedom is larger than the finite element method. To demonstrate the capabilities of this new method we present results for two benchmarks used previously: a falling cube with distinct buoyancy and viscosity, and a Rayleigh-Taylor instability of a compositionally buoyant layer. To evaluate the trade-offs in computational speed and solution accuracy we present results for these same benchmarks using the two field tracking methods available in ASPECT: active tracer particles and the entropy viscosity method.

Accelerated characterization of graphite/epoxy composites

NASA Technical Reports Server (NTRS)

Griffith, W. I.; Morris, D. H.; Brinson, H. F.

1980-01-01

A method to predict the long term compliance of unidirectional off-axis laminates from short term laboratory tests is presented. The method uses an orthotropic transformation equation and the time-stress-temperature superposition principle. Short term tests are used to construct master curves for two off-axis unidirectional laminates with fiber angles of 10 and 90 degrees. Analytical predictions of long term compliance for 30 and 60 degrees laminates are made. Comparisons with experimental data are also given.

The influence of phosphorylation and freezing temperature on the mechanical properties of hydroxyapatite/chitosan composite as bone scaffold biomaterial

NASA Astrophysics Data System (ADS)

Albab, Muh Fadhil; Giovani, Nicholas; Yuwono, Akhmad Herman; Sofyan, Nofrijon; Ramahdita, Ghiska; Whulanza, Yudan

2018-02-01

Biomaterials composite of hydroxyapatite/chitosan is a preeminent material for medical applications including bone scaffold. To improve its mechanical properties, the chitosan as the matrix needs to be modified with particular chemical agents. One of the methods is phosphorylation of chitosan by using orthophosphoric acid prior to the biomaterials fabrication. In the current study, biomaterials with the weight composition of 70% hydroxyapatite (HA) and 30% phosphorylated chitosan have been fabricated using thermally induced phase separation (TIPS) method with freezing temperature variation of -20, -30, -40 and -80°C prior to three day-freeze drying. The results obtained by this work showed that the highest compression modulus of 376.9 kPa, highest compressive strength of 38.4 kPa and biggest pore size of 48.24 µm were achieved in the freezing temperature of -20°C. In comparison to non-phosphorylated chitosan/hydroxyapatite, the modification of chitosan using orthophosphoric acid in this work has been found to increase the compressive strength of composite up to 5.5 times.

Body composition in male elite athletes, comparison of bioelectrical impedance spectroscopy with dual energy X-ray absorptiometry

PubMed Central

Svantesson, Ulla; Zander, Martina; Klingberg, Sofia; Slinde, Frode

2008-01-01

Background The aim of this study was to compare body composition results from bioelectrical spectroscopy (BIS) with results from dual energy X-ray absorptiometry (DXA) in a population of male elite athletes. Body composition was assessed using DXA (Lunar Prodigy, GE Lunar Corp., Madison, USA) and BIS (Hydra 4200, Xitron Technologies Inc, San Diego, California, USA) at the same occasion. Agreement between methods was assessed using paired t-tests and agreement-plots. Results Thirty-three male elite athletes (soccer and ice hockey) were included in the study. The results showed that BIS underestimates the proportion of fat mass by 4.6% points in the ice hockey players. In soccer players the BIS resulted in a lower mean fat mass by 1.1% points. Agreement between the methods at the individual level was highly variable. Conclusion Body composition results assessed by BIS in elite athletes should be interpreted with caution, especially in individual subjects. BIS may present values of fat mass that is either higher or lower than fat mass assessed by DXA, independent of true fat content of the individual. PMID:18211680

A Damage Resistance Comparison Between Candidate Polymer Matrix Composite Feedline Materials

NASA Technical Reports Server (NTRS)

Nettles, A. T

2000-01-01

As part of NASAs focused technology programs for future reusable launch vehicles, a task is underway to study the feasibility of using the polymer matrix composite feedlines instead of metal ones on propulsion systems. This is desirable to reduce weight and manufacturing costs. The task consists of comparing several prototype composite feedlines made by various methods. These methods are electron-beam curing, standard hand lay-up and autoclave cure, solvent assisted resin transfer molding, and thermoplastic tape laying. One of the critical technology drivers for composite components is resistance to foreign objects damage. This paper presents results of an experimental study of the damage resistance of the candidate materials that the prototype feedlines are manufactured from. The materials examined all have a 5-harness weave of IM7 as the fiber constituent (except for the thermoplastic, which is unidirectional tape laid up in a bidirectional configuration). The resin tested were 977-6, PR 520, SE-SA-1, RS-E3 (e-beam curable), Cycom 823 and PEEK. The results showed that the 977-6 and PEEK were the most damage resistant in all tested cases.

Application of Analytic Hierarchy Process (AHP) in the analysis of the fuel efficiency in the automobile industry with the utilization of Natural Fiber Polymer Composites (NFPC)

NASA Astrophysics Data System (ADS)

Jayamani, E.; Perera, D. S.; Soon, K. H.; Bakri, M. K. B.

2017-04-01

A systematic method of material analysis aiming for fuel efficiency improvement with the utilization of natural fiber reinforced polymer matrix composites in the automobile industry is proposed. A multi-factor based decision criteria with Analytical Hierarchy Process (AHP) was used and executed through MATLAB to achieve improved fuel efficiency through the weight reduction of vehicular components by effective comparison between two engine hood designs. The reduction was simulated by utilizing natural fiber polymer composites with thermoplastic polypropylene (PP) as the matrix polymer and benchmarked against a synthetic based composite component. Results showed that PP with 35% of flax fiber loading achieved a 0.4% improvement in fuel efficiency, and it was the highest among the 27 candidate fibers.

Modeling and Testing of the Viscoelastic Properties of a Graphite Nanoplatelet/Epoxy Composite

NASA Technical Reports Server (NTRS)

Odegard, Gregory M.; Gates, Thomas S.

2005-01-01

In order to facilitate the interpretation of experimental data, a micromechanical modeling procedure is developed to predict the viscoelastic properties of a graphite nanoplatelet/epoxy composite as a function of volume fraction and nanoplatelet diameter. The predicted storage and loss moduli for the composite are compared to measured values from the same material using three test methods; Dynamical Mechanical Analysis, nanoindentation, and quasi-static tensile tests. In most cases, the model and experiments indicate that for increasing volume fractions of nanoplatelets, both the storage and loss moduli increase. Also, the results indicate that for nanoplatelet sizes above 15 microns, nanoindentation is capable of measuring properties of individual constituents of a composite system. Comparison of the predicted values to the measured data helps illustrate the relative similarities and differences between the bulk and local measurement techniques.

High throughput sequencing analysis of RNA libraries reveals the influences of initial library and PCR methods on SELEX efficiency.

PubMed

Takahashi, Mayumi; Wu, Xiwei; Ho, Michelle; Chomchan, Pritsana; Rossi, John J; Burnett, John C; Zhou, Jiehua

2016-09-22

The systemic evolution of ligands by exponential enrichment (SELEX) technique is a powerful and effective aptamer-selection procedure. However, modifications to the process can dramatically improve selection efficiency and aptamer performance. For example, droplet digital PCR (ddPCR) has been recently incorporated into SELEX selection protocols to putatively reduce the propagation of byproducts and avoid selection bias that result from differences in PCR efficiency of sequences within the random library. However, a detailed, parallel comparison of the efficacy of conventional solution PCR versus the ddPCR modification in the RNA aptamer-selection process is needed to understand effects on overall SELEX performance. In the present study, we took advantage of powerful high throughput sequencing technology and bioinformatics analysis coupled with SELEX (HT-SELEX) to thoroughly investigate the effects of initial library and PCR methods in the RNA aptamer identification. Our analysis revealed that distinct "biased sequences" and nucleotide composition existed in the initial, unselected libraries purchased from two different manufacturers and that the fate of the "biased sequences" was target-dependent during selection. Our comparison of solution PCR- and ddPCR-driven HT-SELEX demonstrated that PCR method affected not only the nucleotide composition of the enriched sequences, but also the overall SELEX efficiency and aptamer efficacy.

High throughput sequencing analysis of RNA libraries reveals the influences of initial library and PCR methods on SELEX efficiency

PubMed Central

Takahashi, Mayumi; Wu, Xiwei; Ho, Michelle; Chomchan, Pritsana; Rossi, John J.; Burnett, John C.; Zhou, Jiehua

2016-01-01

The systemic evolution of ligands by exponential enrichment (SELEX) technique is a powerful and effective aptamer-selection procedure. However, modifications to the process can dramatically improve selection efficiency and aptamer performance. For example, droplet digital PCR (ddPCR) has been recently incorporated into SELEX selection protocols to putatively reduce the propagation of byproducts and avoid selection bias that result from differences in PCR efficiency of sequences within the random library. However, a detailed, parallel comparison of the efficacy of conventional solution PCR versus the ddPCR modification in the RNA aptamer-selection process is needed to understand effects on overall SELEX performance. In the present study, we took advantage of powerful high throughput sequencing technology and bioinformatics analysis coupled with SELEX (HT-SELEX) to thoroughly investigate the effects of initial library and PCR methods in the RNA aptamer identification. Our analysis revealed that distinct “biased sequences” and nucleotide composition existed in the initial, unselected libraries purchased from two different manufacturers and that the fate of the “biased sequences” was target-dependent during selection. Our comparison of solution PCR- and ddPCR-driven HT-SELEX demonstrated that PCR method affected not only the nucleotide composition of the enriched sequences, but also the overall SELEX efficiency and aptamer efficacy. PMID:27652575

Mineralogical analysis of the Eos family from near-infrared spectra

NASA Astrophysics Data System (ADS)

Mothé-Diniz, T.; Carvano, J. M.; Bus, S. J.; Duffard, R.; Burbine, T. H.

2008-05-01

The aim of this work is to analyze the mineralogy of the Eos family, which exhibits considerable taxonomic diversity. Its biggest fragment, (221) Eos has previously been associated, through direct spectral comparisons, with such diverse mineralogies as CV/CO and achondrite meteorites [Burbine, T.H., Binzel, R.P., Bus, S.J., Clark, B.E., 2001. Meteorit. Planet. Sci. 36, 245-253; Mothé-Diniz, T., Carvano, J.M., 2005. Astron. Astrophys. 174, 54-80]. In order to perform such analysis we obtained spectra of 30 family members in the 0.8-2.5 μm range, and used three different methods of mineralogical inference: direct spectral comparison with meteorites, intimate mixing using Hapke's theory, and fitting absorption features with the MGM. Although the direct comparison failed to yield good matches—the best candidates being R-chondrites—both mixing model and MGM analysis suggest that the bulk of the family is dominated by forsteritic ( Fa) olivine, with a minor component of orthopyroxene. This composition can be compatible with what would be expected from the partial differentiation of a parent-body with an original composition similar to ordinary chondrites, which probably formed and differentiated closer to the Sun than the present location of the family. A CK-like composition is also possible, from the inferred mineralogy, as well as from the similarities of the spectra in the NIR.

Standardization of the Food Composition Database Used in the Latin American Nutrition and Health Study (ELANS).

PubMed

Kovalskys, Irina; Fisberg, Mauro; Gómez, Georgina; Rigotti, Attilio; Cortés, Lilia Yadira; Yépez, Martha Cecilia; Pareja, Rossina G; Herrera-Cuenca, Marianella; Zimberg, Ioná Z; Tucker, Katherine L; Koletzko, Berthold; Pratt, Michael

2015-09-16

Between-country comparisons of estimated dietary intake are particularly prone to error when different food composition tables are used. The objective of this study was to describe our procedures and rationale for the selection and adaptation of available food composition to a single database to enable cross-country nutritional intake comparisons. Latin American Study of Nutrition and Health (ELANS) is a multicenter cross-sectional study of representative samples from eight Latin American countries. A standard study protocol was designed to investigate dietary intake of 9000 participants enrolled. Two 24-h recalls using the Multiple Pass Method were applied among the individuals of all countries. Data from 24-h dietary recalls were entered into the Nutrition Data System for Research (NDS-R) program after a harmonization process between countries to include local foods and appropriately adapt the NDS-R database. A food matching standardized procedure involving nutritional equivalency of local food reported by the study participants with foods available in the NDS-R database was strictly conducted by each country. Standardization of food and nutrient assessments has the potential to minimize systematic and random errors in nutrient intake estimations in the ELANS project. This study is expected to result in a unique dataset for Latin America, enabling cross-country comparisons of energy, macro- and micro-nutrient intake within this region.

Standardization of the Food Composition Database Used in the Latin American Nutrition and Health Study (ELANS)

PubMed Central

Kovalskys, Irina; Fisberg, Mauro; Gómez, Georgina; Rigotti, Attilio; Cortés, Lilia Yadira; Yépez, Martha Cecilia; Pareja, Rossina G.; Herrera-Cuenca, Marianella; Zimberg, Ioná Z.; Tucker, Katherine L.; Koletzko, Berthold; Pratt, Michael

2015-01-01

Between-country comparisons of estimated dietary intake are particularly prone to error when different food composition tables are used. The objective of this study was to describe our procedures and rationale for the selection and adaptation of available food composition to a single database to enable cross-country nutritional intake comparisons. Latin American Study of Nutrition and Health (ELANS) is a multicenter cross-sectional study of representative samples from eight Latin American countries. A standard study protocol was designed to investigate dietary intake of 9000 participants enrolled. Two 24-h recalls using the Multiple Pass Method were applied among the individuals of all countries. Data from 24-h dietary recalls were entered into the Nutrition Data System for Research (NDS-R) program after a harmonization process between countries to include local foods and appropriately adapt the NDS-R database. A food matching standardized procedure involving nutritional equivalency of local food reported by the study participants with foods available in the NDS-R database was strictly conducted by each country. Standardization of food and nutrient assessments has the potential to minimize systematic and random errors in nutrient intake estimations in the ELANS project. This study is expected to result in a unique dataset for Latin America, enabling cross-country comparisons of energy, macro- and micro-nutrient intake within this region. PMID:26389952

Fabrication and mechanical properties of aluminum composite reinforced with functionalized carbon nanotubes

NASA Astrophysics Data System (ADS)

Alavijeh, Elham Zamani; Kokhaei, Saeed; Dehghani, Kamran

2018-01-01

Composite aluminum alloy (5000 series) and multi-walled carbon nanotubes (MWCNTs) were made using mechanical alloying, cold press and sintering. The quality of interactions between Al powders and CNTs in the metal matrix composite has a significant effect on mechanical properties. Motivated from the properties of functionalized CNTs, the current study use this material rather than the raw type, because of its reactivity. Besides, a poly-vinyl-alcohol pre-mixing is done, the aim of which is to enhance mixing process. The functionalized carbon nanotubes ware made by chemically method through refluxing with nitric acid. By this method functional groups have been created on CNTs surfaces. 1% and 3% functionalized carbon nanotubes were manufactured using the aforementioned method. To provide unbiased comparisons, 1% and 3% with raw CNTs and pure aluminum is produced with same manner. The numerical experiments affirm the superiority of the functionalized carbon nano-tubes in terms of the relative density and hardness of nanocomposites. As a final activity, the Fourier transformation infrared spectroscopy and field emission scanning electron microscopy techniques were used to characterize the carbon nanotubes and the powders.

Effluent composition prediction of a two-stage anaerobic digestion process: machine learning and stoichiometry techniques.

PubMed

Alejo, Luz; Atkinson, John; Guzmán-Fierro, Víctor; Roeckel, Marlene

2018-05-16

Computational self-adapting methods (Support Vector Machines, SVM) are compared with an analytical method in effluent composition prediction of a two-stage anaerobic digestion (AD) process. Experimental data for the AD of poultry manure were used. The analytical method considers the protein as the only source of ammonia production in AD after degradation. Total ammonia nitrogen (TAN), total solids (TS), chemical oxygen demand (COD), and total volatile solids (TVS) were measured in the influent and effluent of the process. The TAN concentration in the effluent was predicted, this being the most inhibiting and polluting compound in AD. Despite the limited data available, the SVM-based model outperformed the analytical method for the TAN prediction, achieving a relative average error of 15.2% against 43% for the analytical method. Moreover, SVM showed higher prediction accuracy in comparison with Artificial Neural Networks. This result reveals the future promise of SVM for prediction in non-linear and dynamic AD processes. Graphical abstract ᅟ.

Effects of four different cooking methods on some quality characteristics of low fat Inegol meatball enriched with flaxseed flour.

PubMed

Turp, Gulen Yildiz

2016-11-01

The present study is concerned with the effects of four different cooking methods (grill, oven, pan and ohmic cooking) on physicochemical parameters (cooking yield moisture retention, fat retention, color, texture), fatty acid composition and sensory characteristics of low fat Turkish traditional Inegol meatball. Flaxseed flour was used as a fat substitute in the production of meatballs. Meatball proximate composition was affected by the cooking methods mainly as a consequence of the weight losses. The highest cooking yield was found in samples cooked in the oven. Flaxseed flour contains high amount of α-linolenic acid and ohmic cooking seems to be the best cooking method in terms of retaining this fatty acid in meatballs enriched with flaxseed flour. However ohmic cooked meatball samples had a brighter surface color and harder texture in comparison with meatball samples cooked via traditional methods. There was no significant difference between the sensory evaluation scores of meatballs. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-temperature Friction and Wear Resistance of Ni-Co-SiC Composite Coatings

NASA Astrophysics Data System (ADS)

Guo, Fang; Sun, Wan-chang; Jia, Zong-wei; Liu, Xiao-jia; Dong, Ya-ru

2018-05-01

Ni-Co alloy and SiC micro-particles were co-deposited on 45 steel by electrodeposition for high temperature performance. The high temperature tribological characteristics were studied by use of a ball-on-disk method. The micrographs and phase structure of the Ni-Co-SiC composite coatings after high-temperature friction were observed by using a field emission scanning electron microscope(FESEM). The results reveal that the Ni-Co-SiC composite coating presents better wear resistance and lower friction coefficient at high temperature in comparison with that of Ni-Co coating and 45 steel substrate. The embedded SiC particles could strengthen the alloy coating by dispersion strengthening effect and changing the friction mechanism from adhesive wear to abrasive wear.

Nanofiber/ZrO2-based mixed matrix separator for high safety/high-rate lithium-ion batteries

NASA Astrophysics Data System (ADS)

Xiao, Wei; Liu, Jianguo; Yan, Chuanwei

2017-10-01

A novel asymmetric separator based on a thin bacterial cellulose nanofiber (BCF)/nano-ZrO2 composite layer and a non-woven support was prepared by paper-making method. Owing to the relatively polar constituents and well-developed, gradient porous structure, the separator exhibited the advantages of higher thermal resistance, electrolyte wettability, and ionic conductivity in comparison to polyethylene separator. Based on these advantages, the Li/LiFePO4 cells assembled from this composite separator showed excellent performance characteristics, including outstanding C-rate capability, high capacity and cycling performance. Production of the composite separator is simple, environmentally benign and economically viable. Therefore, it's a good candidate for creating improved lithium-ion batteries.

Quality of Life Outcomes in Community-based Mental Health Consumers: Comparisons with Population Norms and Changes over Time.

PubMed

Happell, Brenda; Stanton, Robert; Hodgetts, Danya; Scott, David

2016-01-01

Quality of life is shown to be lower in people diagnosed with mental illness in comparison to the general population. The aim of this study is to examine the Quality of life in a subset of people accessing mental health services in a regional Queensland Centre. Thirty-seven people accessing mental health services completed the SF36 Health Survey on three occasions. Differences and relationships between Physical Composite Scores and Mental Composite Scores, comparisons with Australian population norms, and temporal change in Quality of Life were examined. Physical Composite Scores were significantly different to, but significantly correlated with, Mental Composite Scores on each occasion. Physical Composite Scores and Mental Composite Scores were significantly different to population norms, and did not vary significantly across time. The poor Quality of life of people with mental illness remains a significant challenge for the mental health workforce.

Zinc (hydr)oxide/graphite oxide/AuNPs composites: role of surface features in H₂S reactive adsorption.

PubMed

Giannakoudakis, Dimitrios A; Bandosz, Teresa J

2014-12-15

Zinc hydroxide/graphite oxide/AuNPs composites with various levels of complexity were synthesized using an in situ precipitation method. Then they were used as H2S adsorbents in visible light. The materials' surfaces were characterized before and after H2S adsorption by various physical and chemical methods (XRD, FTIR, thermal analysis, potentiometric titration, adsorption of nitrogen and SEM/EDX). Significant differences in surface features and synergistic effects were found depending on the materials' composition. Addition of graphite oxide and the deposition of gold nanoparticles resulted in a marked increase in the adsorption capacity in comparison with that on the zinc hydroxide and zinc hydroxide/AuNP. Addition of AuNPs to zinc hydroxide led to a crystalline ZnO/AuNP composite while the zinc hydroxide/graphite oxide/AuNP composite was amorphous. The ZnOH/GO/AuNPs composite exhibited the greatest H2S adsorption capacity due to the increased number of OH terminal groups and the conductive properties of GO that facilitated the electron transfer and consequently the formation of superoxide ions promoting oxidation of hydrogen sulfide. AuNPs present in the composite increased the conductivity, helped with electron transfer to oxygen, and prevented the fast recombination of the electrons and holes. Copyright © 2014 Elsevier Inc. All rights reserved.

Comparison of Curvilinear Stiffeners and Tow Steered Composites for Aeroelastic Tailoring of Transports

NASA Technical Reports Server (NTRS)

Stanford, Bret K.; Jutte, Christine V.

2016-01-01

A series of aeroelastic optimization problems are solved on a high aspect ratio wingbox of the Common Research Model, in an effort to minimize structural mass under coupled stress, buckling, and flutter constraints. Two technologies are of particular interest: tow steered composite laminate skins and curvilinear stiffeners. Both methods are found to afford feasible reductions in mass over their non-curvilinear structural counterparts, through both distinct and shared mechanisms for passively controlling aeroelastic performance. Some degree of diminishing returns are seen when curvilinear stiffeners and curvilinear fiber tow paths are used simultaneously.

Characterization of toners and inkjets by laser ablation spectrochemical methods and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

NASA Astrophysics Data System (ADS)

Trejos, Tatiana; Corzo, Ruthmara; Subedi, Kiran; Almirall, José

2014-02-01

Detection and sourcing of counterfeit currency, examination of counterfeit security documents and determination of authenticity of medical records are examples of common forensic document investigations. In these cases, the physical and chemical composition of the ink entries can provide important information for the assessment of the authenticity of the document or for making inferences about common source. Previous results reported by our group have demonstrated that elemental analysis, using either Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) or Laser Ablation Induced Breakdown Spectroscopy (LIBS), provides an effective, practical and robust technique for the discrimination of document substrates and writing inks with minimal damage to the document. In this study, laser-based methods and Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) methods were developed, optimized and validated for the forensic analysis of more complex inks such as toners and inkjets, to determine if their elemental composition can differentiate documents printed from different sources and to associate documents that originated from the same printing source. Comparison of the performance of each of these methods is presented, including the analytical figures of merit, discrimination capability and error rates. Different calibration strategies resulting in semi-quantitative and qualitative analysis, comparison methods (match criteria) and data analysis and interpretation tools were also developed. A total of 27 black laser toners originating from different manufacturing sources and/or batches were examined to evaluate the discrimination capability of each method. The results suggest that SEM-EDS offers relatively poor discrimination capability for this set (~ 70.7% discrimination of all the possible comparison pairs or a 29.3% type II error rate). Nonetheless, SEM-EDS can still be used as a complementary method of analysis since it has the advantage of being non-destructive to the sample in addition to providing imaging capabilities to further characterize toner samples by their particle morphology. Laser sampling methods resulted in an improvement of the discrimination between different sources with LIBS producing 89% discrimination and LA-ICP-MS resulting in 100% discrimination. In addition, a set of 21 black inkjet samples was examined by each method. The results show that SEM-EDS is not appropriate for inkjet examinations since their elemental composition is typically below the detection capabilities with only sulfur detected in this set, providing only 47.4% discrimination between possible comparison pairs. Laser sampling methods were shown to provide discrimination greater than 94% for this same inkjet set with false exclusion and false inclusion rates lower than 4.1% and 5.7%, for LA-ICP-MS and LIBS respectively. Overall these results confirmed the utility of the examination of printed documents by laser-based micro-spectrochemical methods. SEM-EDS analysis of toners produced a limited utility for discrimination within sources but was not an effective tool for inkjet ink discrimination. Both LA-ICP-MS and LIBS can be used in forensic laboratories to chemically characterize inks on documents and to complement the information obtained by conventional methods and enhance their evidential value.

Effects of Cesarean delivery and formula supplementation on the intestinal microbiome of six-week old infants

PubMed Central

Madan, Juliette C.; Hoen, Anne G.; Lundgren, Sara N.; Farzan, Shohreh F.; Cottingham, Kathryn L.; Morrison, Hilary G.; Sogin, Mitchell L.; Li, Hongzhe; Moore, Jason H.; Karagas, Margaret R.

2016-01-01

Importance The intestinal microbiome plays a critical role in infant development, and delivery mode and feeding method (breastmilk vs. formula) are determinants of its composition. However, the importance of delivery mode beyond the first days of life is unknown, and studies of associations between infant feeding and microbiome composition have been generally limited to comparisons between exclusively breastfed and formula fed infants, with little consideration given to combination feeding of both breastmilk and formula. Objectives To examine the relative effects of delivery mode and feeding method on infant intestinal microbiome composition at approximately six weeks of life. Design, Setting and Participants Prospective observational study of 102 infants followed as part of a US pregnancy cohort study. Exposures Delivery mode was abstracted from delivery medical records and feeding method prior to the time of stool collection was ascertained through detailed questionnaires. Main Outcomes and Measures Stool microbiome composition was characterized using next-generation sequencing of the 16S rRNA gene. Results We identified independent associations between microbial community composition and both delivery mode and feeding method. Differences in microbial community composition between vaginally and infants delivered by Cesarean section were equivalent to or significantly larger than those between feeding groups. Bacterial communities associated with combination feeding were more similar to those associated with exclusive formula feeding than exclusive breastfeeding. We identified individual bacterial genera that were differentially abundant between delivery mode and feeding groups. Conclusions and Relevance The infant intestinal microbiome at approximately six weeks of age is significantly associated with both delivery mode and feeding method, and the supplementation of breastmilk feeding with formula is associated with a microbiome composition that resembles that of infants who are exclusively formula fed. These results may inform feeding choices and shed light on the mechanisms behind the lifelong health consequences of delivery and infant feeding modalities. PMID:26752321

Verification Of The Defense Waste Processing Facility's (DWPF) Process Digestion Methods For The Sludge Batch 8 Qualification Sample

DOE Office of Scientific and Technical Information (OSTI.GOV)

Click, D. R.; Edwards, T. B.; Wiedenman, B. J.

2013-03-18

This report contains the results and comparison of data generated from inductively coupled plasma – atomic emission spectroscopy (ICP-AES) analysis of Aqua Regia (AR), Sodium Peroxide/Sodium Hydroxide Fusion Dissolution (PF) and Cold Chem (CC) method digestions and Cold Vapor Atomic Absorption analysis of Hg digestions from the DWPF Hg digestion method of Sludge Batch 8 (SB8) Sludge Receipt and Adjustment Tank (SRAT) Receipt and SB8 SRAT Product samples. The SB8 SRAT Receipt and SB8 SRAT Product samples were prepared in the SRNL Shielded Cells, and the SRAT Receipt material is representative of the sludge that constitutes the SB8 Batch ormore » qualification composition. This is the sludge in Tank 51 that is to be transferred into Tank 40, which will contain the heel of Sludge Batch 7b (SB7b), to form the SB8 Blend composition.« less

Comparison on extraction yield of sennoside A and sennoside B from senna (Cassia angustifolia) using conventional and non conventional extraction techniques and their quantification using a validated HPLC-PDA detection method.

PubMed

Dhanani, Tushar; Singh, Raghuraj; Reddy, Nagaraja; Trivedi, A; Kumar, Satyanshu

2017-05-01

Senna is an important medicinal plant and is used in many Ayurvedic formulations. Dianthraquinone glucosides are the main bioactive phytochemicals present in leaves and pods of senna. The extraction efficiency in terms of yield and composition of the extract of senna prepared using both conventional (cold percolation at room temperature and refluxing) and non conventional (ultrasound and microwave assisted solvent extraction as well as supercritical fluid extraction) techniques were compared in the present study. Also a rapid reverse phase HPLC-PDA detection method was developed and validated for the simultaneous determination of sennoside A and sennoside B in the different extracts of senna leaves. Ultrasound and microwave assisted solvent extraction techniques were more effective in terms of yield and composition of the extracts compared to cold percolation at room temperature and refluxing methods of extraction.

Visible absorbance spectra: A basis for in situ and passive remote sensing of phytoplankton concentration and community composition

NASA Technical Reports Server (NTRS)

Farmer, F. H.; Jarrett, O., Jr.; Brown, C. A., Jr.

1983-01-01

The concentration and composition of phytoplankton populations are measured by an optical method which can be used either in situ or remotely. This method is based upon the in vivo light absorption characteristics of phytoplankton. To provide a data base for testing assumptions relative to the proposed method, visible absorbance spectra of pure cultures of 20 marine phytoplankton were obtained under laboratory conditions. Descriptive and analytical statistics were computed for the absorbance spectra and were used to make comparisons between members of major taxonomic groups and between groups. Spectral variation between the members of the major taxonomic groups was observed to be considerably less than the spectral variation between these groups. In several cases the differences between the mean absorbance spectra of major taxonomic groups are significant enough to be detected with passive remote sensing techniques.

Microwave-Assisted Hydro-Distillation of Essential Oil from Rosemary: Comparison with Traditional Distillation

PubMed Central

Moradi, Sara; Fazlali, Alireza; Hamedi, Hamid

Background: Hydro-distillation (HD) method is a traditional technique which is used in most industrial companies. Microwave-assisted Hydro-distillation (MAHD) is an advanced HD technique utilizing a microwave oven in the extraction process. Methods: In this research, MAHD of essential oils from the aerial parts (leaves) of rosemary (Rosmarinus officinalis L.) was studied and the results were compared with those of the conventional HD in terms of extraction time, extraction efficiency, chemical composition, quality of the essential oils and cost of the operation. Results: Microwave hydro-distillation was superior in terms of saving energy and extraction time (30 min, compared to 90 min in HD). Chromatography was used for quantity analysis of the essential oils composition. Quality of essential oil improved in MAHD method due to an increase of 17% in oxygenated compounds. Conclusion: Consequently, microwave hydro-distillation can be used as a substitute of traditional hydro-distillation. PMID:29296263

Volume imaging NDE and serial sectioning of carbon fiber composites

NASA Astrophysics Data System (ADS)

Hakim, Issa; Schumacher, David; Sundar, Veeraraghavan; Donaldson, Steven; Creuz, Aline; Schneider, Rainer; Keller, Juergen; Browning, Charles; May, Daniel; Ras, Mohamad Abo; Meyendorf, Norbert

2018-04-01

A composite material is a combination of two or more materials with very different mechanical, thermal and electrical properties. The various forms of composite materials, due to their high material properties, are widely used as structural materials in the aviation, space, marine, automobile, and sports industries. However, some defects like voids, delamination, or inhomogeneous fiber distribution that form during the fabricating processes of composites can seriously affect the mechanical properties of the composite material. In this study, several imaging NDE techniques such as: thermography, high frequency eddy current, ultrasonic, x-ray radiography, x-ray laminography, and high resolution x-ray CT were conducted to characterize the microstructure of carbon fiber composites. Then, a 3D analysis was implemented by the destructive technique of serial sectioning for the same sample tested by the NDE methods. To better analyze the results of this work and extract a clear volume image for all features and defects contained in the composite material, an intensive comparison was conducted among hundreds of 3D-NDE and multi serial sections' scan images showing the microstructure variation.

Normalization and microbial differential abundance strategies depend upon data characteristics.

PubMed

Weiss, Sophie; Xu, Zhenjiang Zech; Peddada, Shyamal; Amir, Amnon; Bittinger, Kyle; Gonzalez, Antonio; Lozupone, Catherine; Zaneveld, Jesse R; Vázquez-Baeza, Yoshiki; Birmingham, Amanda; Hyde, Embriette R; Knight, Rob

2017-03-03

Data from 16S ribosomal RNA (rRNA) amplicon sequencing present challenges to ecological and statistical interpretation. In particular, library sizes often vary over several ranges of magnitude, and the data contains many zeros. Although we are typically interested in comparing relative abundance of taxa in the ecosystem of two or more groups, we can only measure the taxon relative abundance in specimens obtained from the ecosystems. Because the comparison of taxon relative abundance in the specimen is not equivalent to the comparison of taxon relative abundance in the ecosystems, this presents a special challenge. Second, because the relative abundance of taxa in the specimen (as well as in the ecosystem) sum to 1, these are compositional data. Because the compositional data are constrained by the simplex (sum to 1) and are not unconstrained in the Euclidean space, many standard methods of analysis are not applicable. Here, we evaluate how these challenges impact the performance of existing normalization methods and differential abundance analyses. Effects on normalization: Most normalization methods enable successful clustering of samples according to biological origin when the groups differ substantially in their overall microbial composition. Rarefying more clearly clusters samples according to biological origin than other normalization techniques do for ordination metrics based on presence or absence. Alternate normalization measures are potentially vulnerable to artifacts due to library size. Effects on differential abundance testing: We build on a previous work to evaluate seven proposed statistical methods using rarefied as well as raw data. Our simulation studies suggest that the false discovery rates of many differential abundance-testing methods are not increased by rarefying itself, although of course rarefying results in a loss of sensitivity due to elimination of a portion of available data. For groups with large (~10×) differences in the average library size, rarefying lowers the false discovery rate. DESeq2, without addition of a constant, increased sensitivity on smaller datasets (<20 samples per group) but tends towards a higher false discovery rate with more samples, very uneven (~10×) library sizes, and/or compositional effects. For drawing inferences regarding taxon abundance in the ecosystem, analysis of composition of microbiomes (ANCOM) is not only very sensitive (for >20 samples per group) but also critically the only method tested that has a good control of false discovery rate. These findings guide which normalization and differential abundance techniques to use based on the data characteristics of a given study.

ICP-MS Analysis of Lanthanide-Doped Nanoparticles as a Non-Radiative, Multiplex Approach to Quantify Biodistribution and Blood Clearance

PubMed Central

Crayton, Samuel H.; Elias, Andrew; Al-Zaki, Ajlan; Cheng, Zhiliang; Tsourkas, Andrew

2011-01-01

Recent advances in material science and chemistry have led to the development of nanoparticles with diverse physicochemical properties, e.g. size, charge, shape, and surface chemistry. Evaluating which physicochemical properties are best for imaging and therapeutic studies is challenging not only because of the multitude of samples to evaluate, but also because of the large experimental variability associated with in vivo studies (e.g. differences in tumor size, injected dose, subject weight, etc.). To address this issue, we have developed a lanthanide-doped nanoparticle system and analytical method that allows for the quantitative comparison of multiple nanoparticle compositions simultaneously. Specifically, superparamagnetic iron oxide (SPIO) with a range of different sizes and charges were synthesized, each with a unique lanthanide dopant. Following the simultaneous injection of the various SPIO compositions into tumor-bearing mice, inductively coupled plasma mass spectroscopy (ICP-MS) was used to quantitatively and orthogonally assess the concentration of each SPIO composition in serial blood samples and the resected tumor and organs. The method proved generalizable to other nanoparticle platforms, including dendrimers, liposomes, and polymersomes. This approach provides a simple, cost-effective, and non-radiative method to quantitatively compare tumor localization, biodistribution, and blood clearance of more than 10 nanoparticle compositions simultaneously, removing subject-to-subject variability. PMID:22100983

COMPARISON OF ECOLOGICAL COMMUNITIES: THE PROBLEM OF SAMPLE REPRESENTATIVENESS

EPA Science Inventory

Obtaining an adequate, representative sample of ecological communities to make taxon richness (TR) or compositional comparisons among sites is a continuing challenge. Sample representativeness literally means the similarity in species composition and relative abundance between a ...

Accelerated characterization of graphite/epoxy composites

NASA Technical Reports Server (NTRS)

Griffith, W. I.; Morris, D. H.; Brinson, H. F.

1980-01-01

A method to predict the long-term compliance of unidirectional off-axis laminates from short-term laboratory tests is presented. The method uses an orthotropic transformation equation and the time-stress-temperature superposition principle. Short-term tests are used to construct master curves for two off-axis unidirectional laminates with fiber angles of 10 deg and 90 deg. In addition, analytical predictions of long-term compliance for 30 deg and 60 deg laminates are made. Comparisons with experimental data are also given.

Comparison between two methods of hydrostatic weighing without head submersion in morbidly obese females.

PubMed

Israel, R G; Evans, P; Pories, W J; O'Brien, K F; Donnelly, J E

1990-01-01

This study compared two methods of hydrostatic weighing without head submersion to conventional hydrostatic weighting in morbidly obese females. We concluded that hydrostatic weighing without head submersion is a valid alternative to conventional hydrostatic weighing especially when subjects are apprehensive in the water. The use of anthropometric head measures (HWNS-A) did not significantly improve the accuracy of the body composition assessment; therefore, elimination of these time consuming measurements in favor of the direct correction of head above Db is recommended.

Effect of surfactant on microstructure, surface hydrophilicity, mechanical and thermal properties of different multi-walled carbon nanotube/polystyrene composites

NASA Astrophysics Data System (ADS)

Li, Zhipeng; Zhang, Yanxia; Liang, Shaolei; Li, Guangfen

2018-05-01

We prepared nanocomposites of multi-walled carbon nanotube (MWCNT)/polystyrene via a solution casting method, where deionized water was used as coagulation bath. The influences of the type of MWCNTs and existence of surfactant on surface morphology, thermal properties and mechanical properties of MWCNT/polystyrene composites were extensively investigated. The pristine and two functionalized MWCNTs with the loading of 5 wt% were chosen for comparison. Both scanning electron microscopy and mercury intrusion porosimetry show that the composites without surfactant contain fewer pores and thus have higher bulk density, tensile strength, as well as low surface hydrophobicity. However, the porous structures within micro-range appear in all surfactant-treated composites, which decrease the bulk density and the tensile strength of their composites. This especially pronounced for the MWCNT-OH composite as the smallest pore size/highest porosity is found in the composites with loading of 5 wt% MWCNT-OH due to the higher content of hydroxyl groups. Despite the glass transition temperatures (Tg) of all the surfactant-treated composites lower compared with Tg for pure polystyrene, they increase for MWCNTs and MWCNT-OH composite without surfactant.

Assessment of fat and lean mass by quantitative magnetic resonance: a future technology of body composition research?

PubMed

Bosy-Westphal, Anja; Müller, Manfred J

2015-09-01

For the assessment of energy balance or monitoring of therapeutic interventions, there is a need for noninvasive and highly precise methods of body composition analysis that are able to accurately measure small changes in fat and fat-free mass (FFM). The use of quantitative magnetic resonance (QMR) for measurement of body composition has long been established in animal studies. There are, however, only a few human studies that examine the validity of this method. These studies have consistently shown a high precision of QMR and only a small underestimation of fat mass by QMR when compared with a 4-compartment model as a reference. An underestimation of fat mass by QMR is also supported by the comparison between measured energy balance (as a difference between energy intake and energy expenditure) and energy balance predicted from changes in fat mass and FFM. Fewer calories were lost and gained as fat mass compared with the value expected from measured energy balance. Current evidence in healthy humans has shown that QMR is a valid and precise method for noninvasive measurement of body composition. Contrary to standard reference methods, such as densitometry and dual X-ray absorptiometry, QMR results are independent of FFM hydration. However, despite a high accuracy and a low minimal detectable change, underestimation of fat mass by QMR is possible and limits the use of this method for quantification of energy balance.

Copper nanoparticle interspersed MoS2 nanoflowers with enhanced efficiency for CO2 electrochemical reduction to fuel.

PubMed

Shi, Guodong; Yu, Luo; Ba, Xin; Zhang, Xiaoshu; Zhou, Jianqing; Yu, Ying

2017-08-15

Electrocatalytic conversion of carbon dioxide (CO 2 ) has been considered as an ideal method to simultaneously solve the energy crisis and environmental issue around the world. In this work, ultrasmall Cu nanoparticle interspersed flower-like MoS 2 was successfully fabricated via a facile microwave hydrothermal method. The designed optimal hierarchical Cu/MoS 2 composite not only exhibited remarkably enhanced electronic conductivity and specific surface area but also possessed improved CO 2 adsorption capacity, resulting in a significant increase in overall faradaic efficiency and a 7-fold augmentation of the faradaic efficiency of CH 4 in comparison with bare MoS 2 . In addition, the Cu/MoS 2 composite had superior stability with high efficiency retained for 48 h in the electrochemical process. It is anticipated that the designed Cu/MoS 2 composite electrocatalyst may provide new insights for transition metal sulfides and non-noble particles applied to CO 2 reduction.

Portable total reflection x-ray fluorescence analysis in the identification of unknown laboratory hazards

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Ying, E-mail: liu.ying.48r@st.kyoto-u.ac.jp; Imashuku, Susumu; Sasaki, Nobuharu

In this study, a portable total reflection x-ray fluorescence (TXRF) spectrometer was used to analyze unknown laboratory hazards that precipitated on exterior surfaces of cooling pipes and fume hood pipes in chemical laboratories. With the aim to examine the accuracy of TXRF analysis for the determination of elemental composition, analytical results were compared with those of wavelength-dispersive x-ray fluorescence spectrometry, scanning electron microscope and energy-dispersive x-ray spectrometry, energy-dispersive x-ray fluorescence spectrometry, inductively coupled plasma atomic emission spectrometry, x-ray diffraction spectrometry (XRD), and x-ray photoelectron spectroscopy (XPS). Detailed comparison of data confirmed that the TXRF method itself was not sufficient tomore » determine all the elements (Z > 11) contained in the samples. In addition, results suggest that XRD should be combined with XPS in order to accurately determine compound composition. This study demonstrates that at least two analytical methods should be used in order to analyze the composition of unknown real samples.« less

A primary study into graphene/polyether ether ketone (PEEK) nanocomposite for laser sintering

NASA Astrophysics Data System (ADS)

Chen, Binling; Berretta, Silvia; Evans, Ken; Smith, Kaylie; Ghita, Oana

2018-01-01

This paper proposes two methods of preparation of graphene/PEEK powders for Laser Sintering (LS) and investigates their behaviour in relation to their microstructure and their properties. Thin composite films were fabricated in an attempt to replicate the thin layer formation of the powder bed process. Both methods of composite powder preparation (wet and dry) led to enhanced mechanical performance of the composite films at 0.1 and 0.5 wt% graphene nano-platelets (GNP) concentrations. The TEM images show that the GNP act as a nucleation point in crystallisation of PEEK, being at the centre of the spherulites. The hot stage microscopy reveals a 20 s delay in the onset of GNP/PEEK nanocomposite coalescence in comparison with plain PEEK. This is a very important observation for laser sintering, as it will influence the build strategy and specific parameters (e.g. time between layers deposition, multiple exposures). The excellent electrical conductivity properties of graphene were noticeable in the nanocomposite films at concentrations above 1 wt% GNP.

Extraction of essential oil from Cupressus sempervirens: comparison of global yields, chemical composition and antioxidant activity obtained by hydrodistillation and supercritical extraction.

PubMed

Nejia, Herzi; Séverine, Camy; Jalloul, Bouajila; Mehrez, Romdhane; Stéphane, Condoret Jean

2013-01-01

In this study, supercritical fluid extraction (SFE) with CO2 and hydrodistillation (HD) were compared as methods to isolate the essential oil from Cupressus sempervirens. The odour of the oil obtained by SFE at 90 bar and 40°C was very close to the odour of the leaves of C. sempervirens before the extraction. Compounds extracted by both SFE and HD were identified by GC-FID and GC-MS. Moreover, the difference in the chemical composition obtained by SFE and HD was quite noticeable qualitatively and quantitatively. Phenolic composition and antioxidant activity were also determined. Compared to HD, the SFE method presents some advantages: the extraction was completed after 1 h in SFE, although 4 h is necessary for HD, and the yield was improved by 34%. Finally, it has also been shown that SFE is very selective towards some specific components such as manoyl oxide, trans-totarol and α-acoradiene.

Effects of high energy electrons on the properties of polyethylene / multiwalled carbon nanotubes composites: Comparison of as-grown and oxygen-functionalised MWCNT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krause, B., E-mail: krause-beate@ipfdd.de, E-mail: poe@ipfdd.de, E-mail: gohs@ipfdd.de; Pötschke, P., E-mail: krause-beate@ipfdd.de, E-mail: poe@ipfdd.de, E-mail: gohs@ipfdd.de; Gohs, U., E-mail: krause-beate@ipfdd.de, E-mail: poe@ipfdd.de, E-mail: gohs@ipfdd.de

2014-05-15

Polymer modification with high energy electrons (EB) is well established in different applications for many years. It is used for crosslinking, curing, degrading, grafting of polymeric materials and polymerisation of monomers. In contrast to this traditional method, electron induced reactive processing (EIReP) combines the polymer modification with high energy electrons and the melt mixing process. This novel reactive method was used to prepare polymer blends and composites. In this study, both methods were used for the preparation of polyethylene (PE)/ multiwalled carbon nanotubes (MWCNT) composites in the presence of a coupling agent. The influence of MWCNT and type of electronmore » treatment on the gel content, the thermal conductivity, rheological, and electrical properties was investigated whereby as-grown and oxidised MWCNT were used. In the presence of a coupling agent and at an absorbed dose of 40 kGy, the gel content increased from 57 % for the pure PE to 74 % or 88 % by the addition of as-grown (Baytubes® C150P) or oxidised MWCNT, respectively. In comparison to the composites containing the as-grown MWCNTs, the use of the oxidised MWCNTs led to higher melt viscosity and higher storage modulus due to higher yield of filler polymer couplings. The melt viscosity increased due to the addition of MWCNT and crosslinking of PE. The thermal conductivity increased to about 150 % and showed no dependence on the kind of MWCNT and the type of electron treatment. In contrast, the lowest value of electrical volume resistivity was found for the non-irradiated samples and after state of the art electron treatment without any influence of the type of MWCNT. In the case of EIReP, the volume resistivity increased by 2 (as-grown MWCNT) or 3 decades (oxidised MWCNT) depending on the process parameters.« less

Characterization of Hybrid CNT Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Grimsley, Brian W.; Cano, Roberto J.; Kinney, Megan C.; Pressley, James; Sauti, Godfrey; Czabaj, Michael W.; Kim, Jae-Woo; Siochi, Emilie J.

2015-01-01

Carbon nanotubes (CNTs) have been studied extensively since their discovery and demonstrated at the nanoscale superior mechanical, electrical and thermal properties in comparison to micro and macro scale properties of conventional engineering materials. This combination of properties suggests their potential to enhance multi-functionality of composites in regions of primary structures on aerospace vehicles where lightweight materials with improved thermal and electrical conductivity are desirable. In this study, hybrid multifunctional polymer matrix composites were fabricated by interleaving layers of CNT sheets into Hexcel® IM7/8552 prepreg, a well-characterized toughened epoxy carbon fiber reinforced polymer (CFRP) composite. The resin content of these interleaved CNT sheets, as well as ply stacking location were varied to determine the effects on the electrical, thermal, and mechanical performance of the composites. The direct-current electrical conductivity of the hybrid CNT composites was characterized by in-line and Montgomery four-probe methods. For [0](sub 20) laminates containing a single layer of CNT sheet between each ply of IM7/8552, in-plane electrical conductivity of the hybrid laminate increased significantly, while in-plane thermal conductivity increased only slightly in comparison to the control IM7/8552 laminates. Photo-microscopy and short beam shear (SBS) strength tests were used to characterize the consolidation quality of the fabricated laminates. Hybrid panels fabricated without any pretreatment of the CNT sheets resulted in a SBS strength reduction of 70 percent. Aligning the tubes and pre-infusing the CNT sheets with resin significantly improved the SBS strength of the hybrid composite To determine the cause of this performance reduction, Mode I and Mode II fracture toughness of the CNT sheet to CFRP interface was characterized by double cantilever beam (DCB) and end notch flexure (ENF) testing, respectively. Results are compared to the control IM7/8552 laminate.

Digital-data receiver synchronization method and apparatus

DOEpatents

Smith, Stephen F.; Turner, Gary W.

2005-12-06

Digital-data receiver synchronization is provided with composite phase-frequency detectors, mutually cross-connected comparison feedback or both to provide robust reception of digital data signals. A single master clock may be used to provide frequency signals. Advantages can include fast lock-up time in moderately to severely noisy conditions, greater tolerance to noise and jitter when locked, and improved tolerance to clock asymmetries.

Digital-data receiver synchronization method and apparatus

DOEpatents

Smith, Stephen F [Loudon, TN; Turner, Gary W [Clinton, TN

2009-09-08

Digital data receiver synchronization is provided with composite phase-frequency detectors, mutually cross-connected comparison feedback or both to provide robust reception of digital data signals. A single master clock can be used to provide frequency signals. Advantages can include fast lock-up time in moderately to severely noisy conditions, greater tolerance to noise and jitter when locked, and improved tolerance to clock asymmetries.

Comparison of concentration pulse and tracer pulse chromatography: experimental determination of eluent uptake by bridged-ethylene hybrid ultra high performance liquid chromatography packings

USDA-ARS?s Scientific Manuscript database

Excess volume isotherms of acetonitrile and methanol sorbed on a C18 BEH UHPLC packing were determined over a range of pressure, temperature, flow rate and eluent composition. The isotherm measurements were carried out by two independent experimental methods, viz., concentration pulse and tracer pul...

NASTRAN application for the prediction of aircraft interior noise

NASA Technical Reports Server (NTRS)

Marulo, Francesco; Beyer, Todd B.

1987-01-01

The application of a structural-acoustic analogy within the NASTRAN finite element program for the prediction of aircraft interior noise is presented. Some refinements of the method, which reduce the amount of computation required for large, complex structures, are discussed. Also, further improvements are proposed and preliminary comparisons with structural and acoustic modal data obtained for a large, composite cylinder are presented.

Using the 3-Sigma Limit to Identify Significantly Long Pauses during Composing.

ERIC Educational Resources Information Center

Kelly, Leonard P.; Nolan, Thomas W.

Ten deaf college freshmen and a comparison group of five hearing students participated in a study of a method to identify long pauses in written composition that have important statistical properties. Subjects first wrote two initial drafts of short stories they had viewed on video tape. Later, they revised and recopied their two originals and one…

A Comparison of Methods to Screen Middle School Students for Reading and Math Difficulties

ERIC Educational Resources Information Center

Nelson, Peter M.; Van Norman, Ethan R.; Lackner, Stacey K.

2016-01-01

The current study explored multiple ways in which middle schools can use and integrate data sources to predict proficiency on future high-stakes state achievement tests. The diagnostic accuracy of (a) prior achievement data, (b) teacher rating scale scores, (c) a composite score combining state test scores and rating scale responses, and (d) two…

Building a composite score of general practitioners' intrinsic motivation: a comparison of methods.

PubMed

Sicsic, Jonathan; Le Vaillant, Marc; Franc, Carine

2014-04-01

Pay-for-performance programmes have been widely implemented in primary care, but few studies have investigated their potential adverse effects on the intrinsic motivation of general practitioners (GPs) even though intrinsic motivation may be a key determinant of quality in health care. Our aim was to compare methods for developing a composite score of GPs' intrinsic motivation and to select one that is most consistent with self-reported data. A postal survey. French GPs practicing in private practice. Using a set of variables selected to characterize the dimensions of intrinsic motivation, three alternative composite scores were calculated based on a multiple correspondence analysis (MCA), a confirmatory factor analysis (CFA) and a two-parameter logistic model (2-PLM). Weighted kappa coefficients were used to evaluate variation in GPs' ranks according to each method. The three methods produced similar results on both the estimation of the indicators' weights and the order of GP rank lists. All weighted kappa coefficients were >0.80. The CFA and 2-PLM produced the most similar results. There was little difference regarding the three methods' results, validating our measure of GPs' intrinsic motivation. The 2-PLM appeared theoretically and empirically more robust for establishing the intrinsic motivation score. Code JEL C38, C43, I18.

Cost-Benefit Analysis for the Advanced Near Net Shape Technology (ANNST) Method for Fabricating Stiffened Cylinders

NASA Technical Reports Server (NTRS)

Stoner, Mary Cecilia; Hehir, Austin R.; Ivanco, Marie L.; Domack, Marcia S.

2016-01-01

This cost-benefit analysis assesses the benefits of the Advanced Near Net Shape Technology (ANNST) manufacturing process for fabricating integrally stiffened cylinders. These preliminary, rough order-of-magnitude results report a 46 to 58 percent reduction in production costs and a 7-percent reduction in weight over the conventional metallic manufacturing technique used in this study for comparison. Production cost savings of 35 to 58 percent were reported over the composite manufacturing technique used in this study for comparison; however, the ANNST concept was heavier. In this study, the predicted return on investment of equipment required for the ANNST method was ten cryogenic tank barrels when compared with conventional metallic manufacturing. The ANNST method was compared with the conventional multi-piece metallic construction and composite processes for fabricating integrally stiffened cylinders. A case study compared these three alternatives for manufacturing a cylinder of specified geometry, with particular focus placed on production costs and process complexity, with cost analyses performed by the analogy and parametric methods. Furthermore, a scalability study was conducted for three tank diameters to assess the highest potential payoff of the ANNST process for manufacture of large-diameter cryogenic tanks. The analytical hierarchy process (AHP) was subsequently used with a group of selected subject matter experts to assess the value of the various benefits achieved by the ANNST method for potential stakeholders. The AHP study results revealed that decreased final cylinder mass and quality assurance were the most valued benefits of cylinder manufacturing methods, therefore emphasizing the relevance of the benefits achieved with the ANNST process for future projects.

Intra-abdominal fat: Comparison of computed tomography fat segmentation and bioimpedance spectroscopy.

PubMed

Finch, Peter

2017-06-01

Intra-abdominal fat is an important factor in determining the metabolic syndrome/insulin resistance, and thus the risk of diabetes and ischaemic heart disease. Computed Tomography (CT) fat segmentation represents a defined method of quantifying intra-abdominal fat, with attendant radiation risks. Bioimpedance spectroscopy may offer a method of assessment without any risks to the patients. A comparison is made of these two methods. This was a preliminary study of the utility of multifrequency bioimpedance spectroscopy of the mid abdomen as a measure of intra-abdominal fat, by comparison with fat segmentation of an abdominal CT scan in the -30 to -190 HU range. There was a significant (P < 0.01) correlation between intra-abdominal fat and mid-upper arm circumference, as well as the bioimpedance parameter, the R/S ratio. Multivariate analysis showed that these were the only independant variables and allowed the derivation of a formula to estimate intra-abdominal fat: IAF = 0.02 × MAC - 0.757 × R/S + 0.036. Circumabdominal bioimpedance spectroscopy may prove a useful method of assessing intra-abdominal fat, and may be suitable for use in studies to enhance other measures of body composition, such as mid-upper arm circumference.

Fast alignment-free sequence comparison using spaced-word frequencies.

PubMed

Leimeister, Chris-Andre; Boden, Marcus; Horwege, Sebastian; Lindner, Sebastian; Morgenstern, Burkhard

2014-07-15

Alignment-free methods for sequence comparison are increasingly used for genome analysis and phylogeny reconstruction; they circumvent various difficulties of traditional alignment-based approaches. In particular, alignment-free methods are much faster than pairwise or multiple alignments. They are, however, less accurate than methods based on sequence alignment. Most alignment-free approaches work by comparing the word composition of sequences. A well-known problem with these methods is that neighbouring word matches are far from independent. To reduce the statistical dependency between adjacent word matches, we propose to use 'spaced words', defined by patterns of 'match' and 'don't care' positions, for alignment-free sequence comparison. We describe a fast implementation of this approach using recursive hashing and bit operations, and we show that further improvements can be achieved by using multiple patterns instead of single patterns. To evaluate our approach, we use spaced-word frequencies as a basis for fast phylogeny reconstruction. Using real-world and simulated sequence data, we demonstrate that our multiple-pattern approach produces better phylogenies than approaches relying on contiguous words. Our program is freely available at http://spaced.gobics.de/. © The Author 2014. Published by Oxford University Press.

Comparison of body composition, heart rate variability, aerobic and anaerobic performance between competitive cyclists and triathletes

PubMed Central

Arslan, Erşan; Aras, Dicle

2016-01-01

[Purpose] The aim of this study was to compare the body composition, heart rate variability, and aerobic and anaerobic performance between competitive cyclists and triathletes. [Subjects] Six cyclists and eight triathletes with experience in competitions voluntarily participated in this study. [Methods] The subjects’ body composition was measured with an anthropometric tape and skinfold caliper. Maximal oxygen consumption and maximum heart rate were determined using the incremental treadmill test. Heart rate variability was measured by 7 min electrocardiographic recording. The Wingate test was conducted to determine anaerobic physical performance. [Results] There were significant differences in minimum power and relative minimum power between the triathletes and cyclists. Anthropometric characteristics and heart rate variability responses were similar among the triathletes and cyclists. However, triathletes had higher maximal oxygen consumption and lower resting heart rates. This study demonstrated that athletes in both sports have similar body composition and aerobic performance characteristics. PMID:27190476

Efficient removal of arsenic by strategically designed and layer-by-layer assembled PS@+rGO@GO@Fe3O4 composites.

PubMed

Kang, Bong Kyun; Lim, Byeong Seok; Yoon, Yeojoon; Kwag, Sung Hoon; Park, Won Kyu; Song, Young Hyun; Yang, Woo Seok; Ahn, Yong-Tae; Kang, Joon-Wun; Yoon, Dae Ho

2017-10-01

The PS@+rGO@GO@Fe 3 O 4 (PG-Fe 3 O 4 ) hybrid composites for Arsenic removal were successfully fabricated and well dispersed using layer-by-layer assembly and a hydrothermal method. The PG-Fe 3 O 4 hybrid composites were composed of uniformly coated Fe 3 O 4 nanoparticles on graphene oxide layers with water flow space between 3D structures providing many contact area and adsorption sites for Arsenic adsorption. The PG-Fe 3 O 4 hybrid composite has large surface adsorption sites and exhibits high adsorption capacities of 104 mg/g for As (III) and 68 mg/g for As (V) at 25 °C and pH 7 comparison with pure Fe 3 O 4 and P-Fe 3 O 4 samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination and comparison of seed oil triacylglycerol composition of various soybeans (Glycine max (L.)) using ¹H-NMR spectroscopy.

PubMed

Kim, Won Woo; Rho, Ho Sik; Hong, Yong Deog; Yeom, Myung Hun; Shin, Song Seok; Yi, Jun Gon; Lee, Min-Seuk; Park, Hye Yoon; Cho, Dong Ha

2013-11-21

Seed oil triacylglycerol (TAG) composition of 32 soybean varieties were determined and compared using ¹H-NMR. The contents of linolenic (Ln), linoleic (L), and oleic (O) ranged from 10.7% to 19.3%, 37.4%-50.1%, and 15.7%-34.1%, respectively. As is evident, linoleic acid was the major fatty acid of soybean oil. Compositional differences among the varieties were observed. Natural oils containing unsaturated groups have been regarded as important nutrient and cosmetic ingredients because of their various biological activities. The TAG profiles of the soy bean oils could be useful for distinguishing the origin of seeds and controlling the quality of soybean oils. To the best of our knowledge, this is the first study in which the TAG composition of various soybean oils has been analyzed using the ¹H-NMR method.

TiO2 and its composites as effective photocatalyst for glucose degradation processes

NASA Astrophysics Data System (ADS)

Kukh, A. A.; Ivanenko, I. M.; Astrelin, I. M.

2018-03-01

Titanium-dioxide photocatalyst was impregnated onto the activated carbon using originally developed low-temperature sol-gel method to form a TiO2:AC composite material. 15% (mass.) solution Ti2(SO4)3 in sulphuric acid was used as a precursor for photocatalyst synthesis. The highly effective composite material was obtained through a combination of properties of titanium dioxide and activated carbon. Synthesized composites TiO2 with activated carbon demonstrate highly developed surface characteristics and exhibit significantly higher activity in comparison with samples of pure TiO2 synthesized the same way, existing analogues of pure TiO2 synthesized from TiCl3 and even industrial photocatalyst. This was testified by the degradation of 1% aqueous glucose solution using TiO2:AC, samples of pure TiO2 and commercial TiO2 AEROXIDE® TiO2 P25 produced by EVONIK Industries.

Milk composition of free-ranging red hartebeest, giraffe, Southern reedbuck and warthog and a phylogenetic comparison of the milk of African Artiodactyla.

PubMed

Osthoff, G; Hugo, A; Madende, M; Deacon, F; Nel, P J

2017-02-01

The composition of major nutrients and fatty acids of the milk of three species, red hartebeest, Southern reedbuck and warthog, and milk fatty acids of giraffe, that have not been published before, are reported, and together with the same parameters of 11 species previously published, were incorporated in a phylogenetic comparison. Unique properties of milk composition have been observed. Southern reedbuck milk seems to have a complex casein composition, similar to that of sheep. Milk composition varies between species. Although some differences may be ascribed to biological condition, such as stage of lactation, or ecological factors, such as availability of certain nutrients, the contribution by evolutionary history is not well documented and the emphasis is usually on the composition of the macro nutrients. Phylogenetic comparisons often lack representatives of multiple species of taxonomic groups and sub-groups. To date phylogenetic comparisons of milk composition have been carried out by using data from different publications. The problem with this approach is that the ecological factors cannot be completely ruled out. A statistical phylogenetic comparison by PCA between 15 species representing 7 different suborders, families or subfamilies of African Artiodactyla was carried out. The phylogenetic properties showed that the milk composition of the Bovinae, represented here by the subfamilies Bovini and Tragelaphini, differs from the other taxonomic groups, in that the Alcelaphinae had a high milk fat content of the medium chain length fatty acids C8-C12 (>17% of total fatty acids) and the Hippotraginae high amounts of oligosaccharides (>0.4%). Copyright © 2016 Elsevier Inc. All rights reserved.

Accuracy of a simplified method for shielded gamma-ray skyshine sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bassett, M.S.; Shultis, J.K.

1989-11-01

Rigorous transport or Monte Carlo methods for estimating far-field gamma-ray skyshine doses generally are computationally intensive. consequently, several simplified techniques such as point-kernel methods and methods based on beam response functions have been proposed. For unshielded skyshine sources, these simplified methods have been shown to be quite accurate from comparisons to benchmark problems and to benchmark experimental results. For shielded sources, the simplified methods typically use exponential attenuation and photon buildup factors to describe the effect of the shield. However, the energy and directional redistribution of photons scattered in the shield is usually ignored, i.e., scattered photons are assumed tomore » emerge from the shield with the same energy and direction as the uncollided photons. The accuracy of this shield treatment is largely unknown due to the paucity of benchmark results for shielded sources. In this paper, the validity of such a shield treatment is assessed by comparison to a composite method, which accurately calculates the energy and angular distribution of photons penetrating the shield.« less

Comparison of various extraction methods for policosanol from rice bran wax and establishment of chromatographic fingerprint of policosanol.

PubMed

Wang, Mei-Fei; Lian, Hong-Zhen; Mao, Li; Zhou, Jing-Ping; Gong, Hui-Juan; Qian, Bao-Yong; Fang, Yan; Li, Jie

2007-07-11

A capillary gas chromatographic (GC) method has been developed for the separation and determination of policosanol components extracted from rice bran wax. A Varian CP-sil 8 CB column was employed, and an oven temperature was programmed. Gas chromatography-mass spectrometry (GC-MS) was used to identify the composition of policosanol. Quantitative analysis was carried out by means of hydrogen flame ionization detector (FID) with dinonyl phthalate (DNP) as internal standard. The results indicated that the extract obtained by dry saponification has the highest contents of octacosanol and triacontanol among extracts by all used extraction methods including dry saponification, saponification in alcohol, saponification in water (neutralized and non-neutralized), and transesterification. Meanwhile, the GC-MS fingerprint of policosanol extracted by dry saponification has been established. Euclidean distance similarity calculation showed remarkable consistency of compositions and contents among 12 batches of policosanol from a rice bran wax variety. This protocol provided a rapid and feasible method for quality control of policosanol products.

Use of simulated data sets to evaluate the fidelity of metagenomic processing methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mavromatis, K; Ivanova, N; Barry, Kerrie

2007-01-01

Metagenomics is a rapidly emerging field of research for studying microbial communities. To evaluate methods presently used to process metagenomic sequences, we constructed three simulated data sets of varying complexity by combining sequencing reads randomly selected from 113 isolate genomes. These data sets were designed to model real metagenomes in terms of complexity and phylogenetic composition. We assembled sampled reads using three commonly used genome assemblers (Phrap, Arachne and JAZZ), and predicted genes using two popular gene-finding pipelines (fgenesb and CRITICA/GLIMMER). The phylogenetic origins of the assembled contigs were predicted using one sequence similarity-based ( blast hit distribution) and twomore » sequence composition-based (PhyloPythia, oligonucleotide frequencies) binning methods. We explored the effects of the simulated community structure and method combinations on the fidelity of each processing step by comparison to the corresponding isolate genomes. The simulated data sets are available online to facilitate standardized benchmarking of tools for metagenomic analysis.« less

Use of simulated data sets to evaluate the fidelity of Metagenomicprocessing methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mavromatis, Konstantinos; Ivanova, Natalia; Barry, Kerri

2006-12-01

Metagenomics is a rapidly emerging field of research for studying microbial communities. To evaluate methods presently used to process metagenomic sequences, we constructed three simulated data sets of varying complexity by combining sequencing reads randomly selected from 113 isolate genomes. These data sets were designed to model real metagenomes in terms of complexity and phylogenetic composition. We assembled sampled reads using three commonly used genome assemblers (Phrap, Arachne and JAZZ), and predicted genes using two popular gene finding pipelines (fgenesb and CRITICA/GLIMMER). The phylogenetic origins of the assembled contigs were predicted using one sequence similarity--based (blast hit distribution) and twomore » sequence composition--based (PhyloPythia, oligonucleotide frequencies) binning methods. We explored the effects of the simulated community structure and method combinations on the fidelity of each processing step by comparison to the corresponding isolate genomes. The simulated data sets are available online to facilitate standardized benchmarking of tools for metagenomic analysis.« less

Facile synthesis of CuFe2O4-Fe2O3 composite for high-performance supercapacitor electrode applications

NASA Astrophysics Data System (ADS)

Khan, Rashid; Habib, Muhammad; Gondal, Mohammed A.; Khalil, Adnan; Rehman, Zia Ur; Muhammad, Zahir; Haleem, Yasir A.; Wang, Changda; Wu, Chuan Qiang; Song, Li

2017-10-01

We report the synthesis of CuFe2O4-Fe2O3 composite material for efficient and highly stable supercapacitor electrode by using eco-friendly low-temperature co-precipitation method. The CuFe2O4-Fe2O3 composite demonstrated the highest specific capacitance of 638.24 F g-1 and excellent stability up to 2000 charge/discharge cycles. The achieved capacitance value is 16 times higher than that of pure CuFe2O4. The results revealed the extraordinary performance of CuFe2O4-Fe2O3 composite as supercapacitor electrode with excellent retention in comparison to CuFe2O4. The enhanced electrochemical activity of CuFe2O4-Fe2O3 composite is attributed to the synergistic effect which is responsible for redox coupling between Cu2+ and Fe3+ that has never been achieved by single component before.

Synthesis and Characterization of Zr-BASED Amorphous and Crystalline Composite Coating on Ti Substrate by Laser Cladding

NASA Astrophysics Data System (ADS)

Tang, D. M.; Zhang, D. C.; Peng, W.; Luo, Z. C.; Wu, X. Q.; Wang, Y. M.; Lin, J. G.

2014-02-01

A thin strip of a Zr-based alloy with a composition of Zr60Cu25Fe5Al10 (in atom percent) was used as a raw material, and the composite coatings containing Zr-based amorphous phase and crystallites on Ti substrate were fabricated by a one-step laser cladding method without protection. The microstructure, phase constitution, microhardness and wear properties of the coatings were investigated. The results indicate that the microstructure of the coatings is strongly dependent on the laser scanning speed under the conditions of the laser power of 1300 W and laser beam diameter of 6 mm, and the composite coating mainly containing amorphous phase with a small amount of the crystallites can be obtained at the laser scanning speed of 10 mm/s. The composite coating exhibits much higher microhardness than the pure Ti substrate, and thus it behaves superior wear resistance in comparison with the substrate.

Effective media properties of hyperuniform disordered composite materials

PubMed Central

Sheng, Xin-Qing

2017-01-01

The design challenge of new functional composite materials consisting of multiphase materials has attracted an increasing interest in recent years. In particular, understanding the role of distributions of ordered and disordered particles in a host media is scientifically and technologically important for designing novel materials and devices with superior spectral and angular properties. In this work, the effective medium property of disordered composite materials consisting of hyperuniformly distributed hard particles at different filling fractions is investigated. To accurately extract effective permittivity of a disordered composite material, a full-wave finite element method and the transmission line theory are used. Numerical results show that the theory of hyperuniformity can be conveniently used to design disordered composite materials with good accuracy compared with those materials with randomly dispersed particles. Furthermore, we demonstrate that a Luneburg lens based on the proposed hyperuniform media has superior radiation properties in comparison with previously reported metamaterial designs and it may open up a new avenue in electromagnetic materials-by-design. PMID:28982118

Mapping soil particle-size fractions: A comparison of compositional kriging and log-ratio kriging

NASA Astrophysics Data System (ADS)

Wang, Zong; Shi, Wenjiao

2017-03-01

Soil particle-size fractions (psf) as basic physical variables need to be accurately predicted for regional hydrological, ecological, geological, agricultural and environmental studies frequently. Some methods had been proposed to interpolate the spatial distributions of soil psf, but the performance of compositional kriging and different log-ratio kriging methods is still unclear. Four log-ratio transformations, including additive log-ratio (alr), centered log-ratio (clr), isometric log-ratio (ilr), and symmetry log-ratio (slr), combined with ordinary kriging (log-ratio kriging: alr_OK, clr_OK, ilr_OK and slr_OK) were selected to be compared with compositional kriging (CK) for the spatial prediction of soil psf in Tianlaochi of Heihe River Basin, China. Root mean squared error (RMSE), Aitchison's distance (AD), standardized residual sum of squares (STRESS) and right ratio of the predicted soil texture types (RR) were chosen to evaluate the accuracy for different interpolators. The results showed that CK had a better accuracy than the four log-ratio kriging methods. The RMSE (sand, 9.27%; silt, 7.67%; clay, 4.17%), AD (0.45), STRESS (0.60) of CK were the lowest and the RR (58.65%) was the highest in the five interpolators. The clr_OK achieved relatively better performance than the other log-ratio kriging methods. In addition, CK presented reasonable and smooth transition on mapping soil psf according to the environmental factors. The study gives insights for mapping soil psf accurately by comparing different methods for compositional data interpolation. Further researches of methods combined with ancillary variables are needed to be implemented to improve the interpolation performance.

Generalized composite multiscale permutation entropy and Laplacian score based rolling bearing fault diagnosis

NASA Astrophysics Data System (ADS)

Zheng, Jinde; Pan, Haiyang; Yang, Shubao; Cheng, Junsheng

2018-01-01

Multiscale permutation entropy (MPE) is a recently proposed nonlinear dynamic method for measuring the randomness and detecting the nonlinear dynamic change of time series and can be used effectively to extract the nonlinear dynamic fault feature from vibration signals of rolling bearing. To solve the drawback of coarse graining process in MPE, an improved MPE method called generalized composite multiscale permutation entropy (GCMPE) was proposed in this paper. Also the influence of parameters on GCMPE and its comparison with the MPE are studied by analyzing simulation data. GCMPE was applied to the fault feature extraction from vibration signal of rolling bearing and then based on the GCMPE, Laplacian score for feature selection and the Particle swarm optimization based support vector machine, a new fault diagnosis method for rolling bearing was put forward in this paper. Finally, the proposed method was applied to analyze the experimental data of rolling bearing. The analysis results show that the proposed method can effectively realize the fault diagnosis of rolling bearing and has a higher fault recognition rate than the existing methods.

Predicting the Mineral Composition of Dust Aerosols. Part 1; Representing Key Processes

NASA Technical Reports Server (NTRS)

Perlwitz, J. P.; Garcia-Pando, C. Perez; Miller, R. L.

2015-01-01

Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wetsieved soil and the emitted aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent at these diameters in a soil whose aggregates are dispersed by wet sieving. We calculate the emitted mass of each mineral with respect to size by accounting for the disintegration of soil aggregates during wet sieving. These aggregates are emitted during mobilization and fragmentation of the original undispersed soil that is subject to wind erosion. The emitted aggregates are carried far downwind from their parent soil. The soil mineral fractions used to calculate the aggregates also include larger particles that are suspended only in the vicinity of the source. We calculate the emitted size distribution of these particles using a normalized distribution derived from aerosol measurements. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to measurements from North Africa shows that the model extensions result in better agreement, consistent with a more extensive comparison to global observations as well as measurements of elemental composition downwind of the Sahara, as described in companion articles.

Predicting the mineral composition of dust aerosols - Part 1: Representing key processes

NASA Astrophysics Data System (ADS)

Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

2015-10-01

Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wet-sieved soil and the emitted aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent at these diameters in a soil whose aggregates are dispersed by wet sieving. We calculate the emitted mass of each mineral with respect to size by accounting for the disintegration of soil aggregates during wet sieving. These aggregates are emitted during mobilization and fragmentation of the original undispersed soil that is subject to wind erosion. The emitted aggregates are carried far downwind from their parent soil. The soil mineral fractions used to calculate the aggregates also include larger particles that are suspended only in the vicinity of the source. We calculate the emitted size distribution of these particles using a normalized distribution derived from aerosol measurements. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to measurements from North Africa shows that the model extensions result in better agreement, consistent with a more extensive comparison to global observations as well as measurements of elemental composition downwind of the Sahara, as described in companion articles.

Intercomparisons of airborne measurements of aerosol ionic chemical composition during TRACE-P and ACE-Asia

NASA Astrophysics Data System (ADS)

Ma, Y.; Weber, R. J.; Maxwell-Meier, K.; Orsini, D. A.; Lee, Y.-N.; Huebert, B. J.; Howell, S. G.; Bertram, T.; Talbot, R. W.; Dibb, J. E.; Scheuer, E.

2004-08-01

As part of the two field studies, Transport and Chemical Evolution over the Pacific (TRACE-P) and the Asian Aerosol Characterization Experiment (ACE-Asia), the inorganic chemical composition of tropospheric aerosols was measured over the western Pacific from three separate aircraft using various methods. Comparisons are made between the rapid online techniques of the particle into liquid sampler (PILS) for measurement of a suite of fine particle a mist chamber/ion chromatograph (MC/IC) measurement of fine sulfate, and the longer time-integrated filter and micro-orifice impactor (MOI) measurements. Comparisons between identical PILS on two separate aircraft flying in formation showed that they were highly correlated (e.g., sulfate r2 of 0.95), but were systematically different by 10 ± 5% (linear regression slope and 95% confidence bounds), and had generally higher concentrations on the aircraft with a low-turbulence inlet and shorter inlet-to-instrument transmission tubing. Comparisons of PILS and mist chamber measurements of fine sulfate on two different aircraft during formation flying had an r2 of 0.78 and a relative difference of 39% ± 5%. MOI ionic data integrated to the PILS upper measurement size of 1.3 μm sampling from separate inlets on the same aircraft showed that for sulfate, PILS and MOI were within 14% ± 6% and correlated with an r2 of 0.87. Most ionic compounds were within ±30%, which is in the range of differences reported between PILS and integrated samplers from ground-based comparisons. In many cases, direct intercomparison between the various instruments is difficult due to differences in upper-size detection limits. However, for this study, the results suggest that the fine particle mass composition measured from aircraft agree to within 30-40%.

Intercomparisons of Airborne Measurements of Aerosol Ionic Chemical Composition during TRACE-P and ACE-Asia

NASA Technical Reports Server (NTRS)

Ma, Y.; Weber, R. J.; Maxwell-Meier, K.; Orsini, D. A.; Lee, Y.-N.; Huebert, B. J.; Howell, S. G.; Bertram, T.; Talbot, R. W.

2003-01-01

As part of the two field studies, Transport and Chemical Evolution over the Pacific (TRACE-P), and the Asian Aerosol Characterization Experiment (ACEAsia), the inorganic chemical composition of tropospheric aerosols was measured over the western Pacific from three separate aircraft using various methods. Comparisons are made between the rapid online techniques of the Particle Into Liquid Sampler (PILS) for measurement of a suite of fine particle ionic compounds and a mist chamber (MC/IC) measurement of fine sulfate, and the longer time-integrated filter and multi-orifice impactor (MOI) measurements. Comparisons between identical PILS on two separate aircraft flying in formation showed that they were highly correlated (e.g., sulfate r(sup 2) of 0.95), but were systematically different by 10 +/- 5% (linear regression slope and 95% confidence bounds), and had generally higher concentrations on the aircraft with a low turbulence inlet and shorter inlet-to-instrument transmission tubing. Comparisons of PILS and mist chamber measurements of fine sulfate on two different aircraft during formation flying had an 3 of 0.78 and a relative difference of 39% +/- 5%. MOI ionic data integrated to the PILS upper measurement size of 1.3 pm sampling from separate inlets on the same aircraft showed that for sulfate, PILS and MOI were within 14% +/- 6% and correlated with an r(sup 2) of 0.87. Most ionic compounds were within f 30%, which is in the range of differences reported between PILS and integrated samplers from ground-based comparisons. In many cases, direct intercomparison between the various instruments is difficult due to differences in upper-size detection limits. However, for this study, the results suggest that the fine particle mass composition measured from aircraft agree to within 30-40%.

Micromechanics of Composite Materials Governed by Vector Constitutive Laws

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Aboudi, Jacob; Arnold, Steven M.

2017-01-01

The high-fidelity generalized method of cells micromechanics theory has been extended for the prediction of the effective property tensor and the corresponding local field distributions for composites whose constituents are governed by vector constitutive laws. As shown, the shear analogy, which can predict effective transverse properties, is not valid in the general three-dimensional case. Consequently, a general derivation is presented that is applicable to both continuously and discontinuously reinforced composites with arbitrary vector constitutive laws and periodic microstructures. Results are given for thermal and electric problems, effective properties and local field distributions, ordered and random microstructures, as well as complex geometries including woven composites. Comparisons of the theory's predictions are made to test data, numerical analysis, and classical expressions from the literature. Further, classical methods cannot provide the local field distributions in the composite, and it is demonstrated that, as the percolation threshold is approached, their predictions are increasingly unreliable. XXXX It has been observed that the bonding between the fibers and matrix in composite materials can be imperfect. In the context of thermal conductivity, such imperfect interfaces have been investigated in micromechanical models by Dunn and Taya (1993), Duan and Karihaloo (2007), Nan et al. (1997) and Hashin (2001). The present HFGMC micromechanical method, derived for perfectly bonded composite materials governed by vector constitutive laws, can be easily generalized to include the effects of weak bonding between the constituents. Such generalizations, in the context of the mechanical micromechanics problem, involve introduction of a traction-separation law at the fiber/matrix interface and have been presented by Aboudi (1987), Bednarcyk and Arnold (2002), Bednarcyk et al. (2004) and Aboudi et al. (2013) and will be addressed in the future.

Comparison of heat and mass transfer of different microwave-assisted extraction methods of essential oil from Citrus limon (Lisbon variety) peel.

PubMed

Golmakani, Mohammad-Taghi; Moayyedi, Mahsa

2015-11-01

Dried and fresh peels of Citrus limon were subjected to microwave-assisted hydrodistillation (MAHD) and solvent-free microwave extraction (SFME), respectively. A comparison was made between MAHD and SFME with the conventional hydrodistillation (HD) method in terms of extraction kinetic, chemical composition, and antioxidant activity. Higher yield results from higher extraction rates by microwaves and could be due to a synergy of two transfer phenomena: mass and heat acting in the same way. Gas chromatography/mass spectrometry (GC/MS) analysis did not indicate any noticeable differences between the constituents of essential oils obtained by MAHD and SFME, in comparison with HD. Antioxidant analysis of the extracted essential oils indicated that microwave irradiation did not have adverse effects on the radical scavenging activity of the extracted essential oils. The results of this study suggest that MAHD and SFME can be termed as green technologies because of their less energy requirements per ml of essential oil extraction.

A comparison of field methods to assess body composition in a diverse group of sedentary women.

PubMed

D'Alonzo, Karen T; Aluf, Ana; Vincent, Linda; Cooper, Kristin

2009-01-01

Accurate assessment of body composition is essential in the evaluation of obesity. While laboratory methods are commonly used to assess fat mass, field measures (e.g., skinfold thickness [SKF] and bioelectrical impedance [BIA]) may be more practical for screening large numbers of individuals in intervention studies. In this study, a correlational design was used among 46 racially and ethnically diverse, sedentary women (mean age = 25.73 years) to (a) compare the percentage of body fat as determined by SKF and the upper body BIA and (b) examine the effects of body mass index (BMI), racial/ethnic background, age, and stage of the menstrual cycle on differences in the estimated percentage of body fat obtained using the SKF and BIA. Overall, a significant correlation between SKF and BIA (r = .98, p < .001) was found, with similar findings among Black, Hispanic and White non-Hispanic women. The mean differences between BIA and SKF were not significantly correlated with BMI, age, race/ethnicity or stage of the menstrual cycle. Data from this study suggest that BIA showed similar body fat prediction values compared with SKF and may be a viable alternative to SKF among diverse groups of healthy women. Additional testing and comparison of these field methods with the laboratory methods of hydro-densitometry or dual energy X-ray absorptiometry is recommended to further determine whether BIA devices can be routinely recommended as an alternative to the SKF.

Comparison of the Debonding Characteristics of Conventional and New Debonding Instrument used for Ceramic, Composite and Metallic Brackets – An Invitro Study

PubMed Central

Gill, Vikas; Reddy, Y. N. N.; Sanadhya, Sudhanshu; Aapaliya, Pankaj; Sharma, Nidhi

2014-01-01

Background: Debonding procedure is time consuming and damaging to the enamel if performed with improper technique. Various debonding methods include: the conventional methods that use pliers or wrenches, an ultrasonic method, electrothermal devices, air pressure impulse devices, diamond burs to grind the brackets off the tooth surface and lasers. Among all these methods, using debonding pliers is most convenient and effective method but has been reported to cause damage to the teeth. Recently, a New Debonding Instrument designed specifically for ceramic and composite brackets has been introduced. As this is a new instrument, little information is available on efficacy of this instrument. The purpose of this study was to evaluate the debonding characteristics of both “the conventional debonding Pliers” and “the New debonding instrument” when removing ceramic, composite and metallic brackets. Materials and Methods: One Hundred Thirty eight extracted maxillary premolar teeth were collected and divided into two Groups: Group A and Group B (n = 69) respectively. They were further divided into 3 subGroups (n = 23) each according to the types of brackets to be bonded. In subGroups A1 and B1{stainless steel};A2 and B2{ceramic};A3 and B3{composite}adhesive precoated maxillary premolar brackets were used. Among them {ceramic and composite} adhesive pre-coated maxillary premolar brackets were bonded. All the teeth were etched using 37% phosphoric acid for 15 seconds and the brackets were bonded using Transbond XT primer. Brackets were debonded using Conventional Debonding Plier and New Debonding Instrument (Group B). After debonding, the enamel surface of each tooth was examined under stereo microscope (10X magnifications). Amodifiedadhesive remnant index (ARI) was used to quantify the amount of remaining adhesive on each tooth. Results: The observations demonstrate that the results of New Debonding Instrument for debonding of metal, ceramic and composite brackets were statistically significantly different (p = 0.04) and superior from the results of conventional debonding Pliers. Conclusion: The debonding efficiency of New Debonding Instrument is better than the debonding efficiency of Conventional Debonding Pliers for use of metal, ceramic and composite brackets respectively. PMID:25177639

Support vector machine regression (SVR/LS-SVM)--an alternative to neural networks (ANN) for analytical chemistry? Comparison of nonlinear methods on near infrared (NIR) spectroscopy data.

PubMed

Balabin, Roman M; Lomakina, Ekaterina I

2011-04-21

In this study, we make a general comparison of the accuracy and robustness of five multivariate calibration models: partial least squares (PLS) regression or projection to latent structures, polynomial partial least squares (Poly-PLS) regression, artificial neural networks (ANNs), and two novel techniques based on support vector machines (SVMs) for multivariate data analysis: support vector regression (SVR) and least-squares support vector machines (LS-SVMs). The comparison is based on fourteen (14) different datasets: seven sets of gasoline data (density, benzene content, and fractional composition/boiling points), two sets of ethanol gasoline fuel data (density and ethanol content), one set of diesel fuel data (total sulfur content), three sets of petroleum (crude oil) macromolecules data (weight percentages of asphaltenes, resins, and paraffins), and one set of petroleum resins data (resins content). Vibrational (near-infrared, NIR) spectroscopic data are used to predict the properties and quality coefficients of gasoline, biofuel/biodiesel, diesel fuel, and other samples of interest. The four systems presented here range greatly in composition, properties, strength of intermolecular interactions (e.g., van der Waals forces, H-bonds), colloid structure, and phase behavior. Due to the high diversity of chemical systems studied, general conclusions about SVM regression methods can be made. We try to answer the following question: to what extent can SVM-based techniques replace ANN-based approaches in real-world (industrial/scientific) applications? The results show that both SVR and LS-SVM methods are comparable to ANNs in accuracy. Due to the much higher robustness of the former, the SVM-based approaches are recommended for practical (industrial) application. This has been shown to be especially true for complicated, highly nonlinear objects.

Comparison of different methods for extraction of Cinnamomi ramulus: yield, chemical composition and in vitro antiviral activities.

PubMed

Zhou, Jing; Yuan, Xiurong; Li, Ling; Zhang, Tong; Wang, Bing

2017-12-01

Hydrodistillation (HD), supercritical fluid extraction (SFE) and reflux extraction (RE) were applied to obtain Cinnamomi ramulus extracts. The yields, chemical compositions and antiviral activities of the extracts were investigated. Extracts were analysed using gas chromatography-mass spectrometry and the antiviral activities were evaluated using cytopathic effect inhibition assay. HD, SFE and RE afforded 0.376, 1.227 and 5.914% yields, respectively. Cinnamaldehyde (CA), SFE and ethanol extracts exhibited antiviral activities against herpes simplex virus type 1. Moreover, CA and other three extracts had inhibition efficacy against respiratory syncytial virus. The most efficient antiviral activities were obtained with SFE.

Numerical optimization of composite hip endoprostheses under different loading conditions

NASA Technical Reports Server (NTRS)

Blake, T. A.; Davy, D. T.; Saravanos, D. A.; Hopkins, D. A.

1992-01-01

The optimization of composite hip implants was investigated. Emphasis was placed on the effect of shape and material tailoring of the implant to improve the implant-bone interaction. A variety of loading conditions were investigated to better understand the relationship between loading and optimization outcome. Comparisons of the initial and optimal models with more complex 3D finite element models were performed. The results indicate that design improvements made using this method result in similar improvements in the 3D models. Although the optimization outcomes were significantly affected by the choice of loading conditions, certain trends were observed that were independent of the applied loading.

A simple formula for the effective complex conductivity of periodic fibrous composites with interfacial impedance and applications to biological tissues

NASA Astrophysics Data System (ADS)

Bisegna, Paolo; Caselli, Federica

2008-06-01

This paper presents a simple analytical expression for the effective complex conductivity of a periodic hexagonal arrangement of conductive circular cylinders embedded in a conductive matrix, with interfaces exhibiting a capacitive impedance. This composite material may be regarded as an idealized model of a biological tissue comprising tubular cells, such as skeletal muscle. The asymptotic homogenization method is adopted, and the corresponding local problem is solved by resorting to Weierstrass elliptic functions. The effectiveness of the present analytical result is proved by convergence analysis and comparison with finite-element solutions and existing models.

Thermally induced stresses in cross-ply composite tubes

NASA Technical Reports Server (NTRS)

Hyer, M. W.; Cooper, D. E.; Tompkins, S. S.

1986-01-01

An approximate solution for determining stresses in cross-ply composite tubes subjected to a circumferential temperature gradient is presented. The solution is based on the principle of complementary virtual work (PCVW) in conjunction with a Ritz approximation on the stress field and accounts for the temperature dependence of material properties. The PCVW method is compared with a planar elasticity solution using temperature-independent material properties and a Navier approach. The net effect of including temperature-dependent material properties is that the peak absolute values of the stresses are reduced. The dependence of the stresses on the circumferential location is also reduced in comparison with the case of temperature-independent properties.

Comparison of geochemical data obtained using four brine sampling methods at the SECARB Phase III Anthropogenic Test CO2 injection site, Citronelle Oil Field, Alabama

USGS Publications Warehouse

Conaway, Christopher; Thordsen, James J.; Manning, Michael A.; Cook, Paul J.; Trautz, Robert C.; Thomas, Burt; Kharaka, Yousif K.

2016-01-01

The chemical composition of formation water and associated gases from the lower Cretaceous Paluxy Formation was determined using four different sampling methods at a characterization well in the Citronelle Oil Field, Alabama, as part of the Southeast Regional Carbon Sequestration Partnership (SECARB) Phase III Anthropogenic Test, which is an integrated carbon capture and storage project. In this study, formation water and gas samples were obtained from well D-9-8 #2 at Citronelle using gas lift, electric submersible pump, U-tube, and a downhole vacuum sampler (VS) and subjected to both field and laboratory analyses. Field chemical analyses included electrical conductivity, dissolved sulfide concentration, alkalinity, and pH; laboratory analyses included major, minor and trace elements, dissolved carbon, volatile fatty acids, free and dissolved gas species. The formation water obtained from this well is a Na–Ca–Cl-type brine with a salinity of about 200,000 mg/L total dissolved solids. Differences were evident between sampling methodologies, particularly in pH, Fe and alkalinity. There was little gas in samples, and gas composition results were strongly influenced by sampling methods. The results of the comparison demonstrate the difficulty and importance of preserving volatile analytes in samples, with the VS and U-tube system performing most favorably in this aspect.

English to Arabic Translation of the Composite Abuse Scale (CAS): A Multi-Method Approach

PubMed Central

Alhabib, Samia; Feder, Gene; Horwood, Jeremy

2013-01-01

Background The composite abuse scale (CAS) is a comprehensive tool used to measure intimate partner violence (IPV). The aim of the present study is to translate the CAS from English to Arabic. Methods The translation of the CAS was conducted in four stages using a multi-method approach: 1) preliminary forward translation, 2) discussion with a panel of bilingual experts, 3) focus groups discussion, and 4) back-translation of the CAS. The discussion included a linguistic validation by a comparison of the Arabic translation with the original English by assessing conceptual and content equivalence. Findings In all the stages of translation, there was an agreement to remove the question from the CAS that asked women about the use of objects in the vagina. Wording, format and order of the items were refined according to comments and suggestions made by the experts’ panel and focus groups’ members. The back-translated CAS showed similar wording and language of the original English version. Conclusions The Arabic version of the CAS will help to measure the problem of IPV among Saudi women and possibly other Arabic-speaking women in future studies. This is important, particularly, in longitudinal studies or intervention studies among abused women and it allows a comparison of the results of studies from different cultures. However, further validations studies are needed to ensure accurate and equivalent Arabic translation of the CAS. PMID:24086478

Solid particle erosion of polymers and composites

NASA Astrophysics Data System (ADS)

Friedrich, K.; Almajid, A. A.

2014-05-01

After a general introduction to the subject of solid particle erosion of polymers and composites, the presentation focusses more specifically on the behavior of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites under such loadings, using different impact conditions and erodents. The data were analyzed on the basis of a newly defined specific erosive wear rate, allowing a better comparison of erosion data achieved under various testing conditions. Characteristic wear mechanisms of the CF/PEEK composites consisted of fiber fracture, matrix cutting and plastic matrix deformation, the relative contribution of which depended on the impingement angles and the CF orientation. The highest wear rates were measured for impingement angles between 45 and 60°. Using abrasion resistant neat polymer films (in this case PEEK or thermoplastic polyurethane (TPU) ones) on the surface of a harder substrate (e.g. a CF/PEEK composite plate) resulted in much lower specific erosive wear rates. The use of such polymeric films can be considered as a possible method to protect composite surfaces from damage caused by minor impacts and erosion. In fact, they are nowadays already successfully applied as protections for wind energy rotor blades.

MEASUREMENT OF BODY COMPOSITION CHANGES WITH WEIGHT LOSS IN POSTMENOPAUSAL WOMEN: COMPARISON OF METHODS

PubMed Central

MAHON, A.K.; FLYNN, M.G.; IGLAY, H.B.; STEWART, L.K.; JOHNSON, C.A.; MCFARLIN, B.K.; CAMPBELL, W.W.

2008-01-01

Background The accurate measurement of body composition changes is important when evaluating the efficacy of medical nutrition therapy and weight management programs, yet is not well documented in older women. Objective We compared methods of estimating energy-restriction-induced body composition changes in postmenopausal women. Design: 27 women (59 ± 8 y; BMI 29.0 ± 2.9 kg/m2; mean ± SD) completed a 9-wk energy restriction period (5233 kJ/d, (1250 kcal/d)). Changes in % body fat (Δ%BF), fat mass (ΔFM), and fat-free mass (ΔFFM) were measured by hydrostatic weighing (HW), air-displacement plethysmography (ADP), dual-energy x-ray absorptiometry (DXA), and deuterium oxide dilution (D2O). The Baumgartner et al. (Am J Clin Nutr 53:1345−1353, 1991) four-compartment (4C) model with body volume from HW was the criterion method. The 4C model with body volume from ADP was also compared. Regression equations were developed based on 4CHW (dependent variable) utilizing results of change (POST-PRE) for each method. Results The women lost 6.8 ± 3.2 kg; 9% of baseline weight. Based on 4CHW, the body composition changes were −2.4 ± 4.5 Δ%BF, −4.7 ± 3.3 kg ΔFM, and −2.6 ± 4.4 kg ΔFFM. No differences were detected by ANOVA for Δ%BF, ΔFM, and ΔFFM among 4CHW, HW, ADP, DXA, D2O, and 4CADP. Bland-Altman limits of agreement showed differences between methods that ranged from 14.5 to −14.1 Δ%BF, 7.8 to −8.1 kg ΔFM, and 7.5 to −8.4 kg ΔFFM for individuals. A bias was shown with 4CADP overestimating Δ%BF (1.4 %) and FM (0.6 kg) and underestimating ΔFFM (−1.2 kg) compared to 4CHW. The regression model was acceptable for %BF (4CADP, 2CHW, and 2CD2O); FM and FFM (4CADP, 3CDXA, 2CHW, and 2CD2O), but not for other estimates of %BF, FM, FFM. Conclusions These body composition assessment methods may be used interchangeably to quantify changes in % body fat, fat mass, and fat-free mass with weight loss in groups of postmenopausal women. 4CADP overestimates Δ%BF and underestimates ΔFFM. When utilizing one of these comparison methods (4CADP, 3CDXA, 2CHW, 2CD2O) to quantify changes in fat mass and fat-free mass for an individual postmenopausal woman, regression equations may be used to relate the data to 4CHW. PMID:17508096

Polish Vocabulary Development in 2-Year-Olds: Comparisons with English Using the Language Development Survey

ERIC Educational Resources Information Center

Rescorla, Leslie; Constants, Holly; Bialecka-Pikul, Marta; Stepien-Nycz, Malgorzata; Ochal, Anna

2017-01-01

Purpose: The objective of this study was to compare vocabulary size and composition in 2-year-olds learning Polish or English as measured by the Language Development Survey (LDS; Rescorla, 1989). Method: Participants were 199 Polish toddlers (M = 24.14 months, SD = 0.35) and 422 U.S. toddlers (M = 24.69 months, SD = 0.78). Results: Test-retest…

Quantitative Comparison of Tumor Delivery for Multiple Targeted Nanoparticles Simultaneously by Multiplex ICP-MS

PubMed Central

Elias, Andrew; Crayton, Samuel H.; Warden-Rothman, Robert; Tsourkas, Andrew

2014-01-01

Given the rapidly expanding library of disease biomarkers and targeting agents, the number of unique targeted nanoparticles is growing exponentially. The high variability and expense of animal testing often makes it unfeasible to examine this large number of nanoparticles in vivo. This often leads to the investigation of a single formulation that performed best in vitro. However, nanoparticle performance in vivo depends on many variables, many of which cannot be adequately assessed with cell-based assays. To address this issue, we developed a lanthanide-doped nanoparticle method that allows quantitative comparison of multiple targeted nanoparticles simultaneously. Specifically, superparamagnetic iron oxide (SPIO) nanoparticles with different targeting ligands were created, each with a unique lanthanide dopant. Following the simultaneous injection of the various SPIO compositions into tumor-bearing mice, inductively coupled plasma mass spectroscopy was used to quantitatively and orthogonally assess the concentration of each SPIO composition in serial blood and resected tumor samples. PMID:25068300

Optimal information networks: Application for data-driven integrated health in populations

PubMed Central

Servadio, Joseph L.; Convertino, Matteo

2018-01-01

Development of composite indicators for integrated health in populations typically relies on a priori assumptions rather than model-free, data-driven evidence. Traditional variable selection processes tend not to consider relatedness and redundancy among variables, instead considering only individual correlations. In addition, a unified method for assessing integrated health statuses of populations is lacking, making systematic comparison among populations impossible. We propose the use of maximum entropy networks (MENets) that use transfer entropy to assess interrelatedness among selected variables considered for inclusion in a composite indicator. We also define optimal information networks (OINs) that are scale-invariant MENets, which use the information in constructed networks for optimal decision-making. Health outcome data from multiple cities in the United States are applied to this method to create a systemic health indicator, representing integrated health in a city. PMID:29423440

Ultrasonic Nondestructive Evaluation Techniques Applied to the Quantitative Characterization of Textile Composite Materials

NASA Technical Reports Server (NTRS)

Miller, James G.

1997-01-01

In this Progress Report, we describe our recent developments of advanced ultrasonic nondestructive evaluation methods applied to the characterization of anisotropic materials. We present images obtained from experimental measurements of ultrasonic diffraction patterns for a thin woven composite in an immersion setup. In addition, we compare apparent signal loss measurements of the thin woven composite for phase-sensitive and phase-insensitive detection methods. All images of diffraction patterns have been included on the accompanying CD-ROM in the Adobe(Trademark) Portable Document Format (PDF). Due to the extensive amount of data, however, hardcopies of only a small representative selection of the images are included within the printed report. This Progress Report presents experimental results that support successful implementation of single element as well as one and two-dimensional ultrasonic array technologies for the inspection of textile composite structures. In our previous reports, we have addressed issues regarding beam profiles of ultrasonic pressure fields transmitted through a water reference path and transmitted through a thin woven composite sample path. Furthermore, we presented experimental results of the effect of a thin woven composite on the magnitude of an insonifying ultrasonic pressure field. In addition to the study of ultrasonic beam profiles, we consider issues relevant to the application of single-element, one-dimensional, and two-dimensional array technologies towards probing the mechanical properties of advanced engineering composites and structures. We provide comparisons between phase-sensitive and phase-insensitive detection methods for determination of textile composite structure parameters. We also compare phase-sensitive and phase-insensitive - - ---- ----- apparent signal loss measurements in an effort to study the phenomenon of phase cancellation at the face of a finite-aperture single-element receiver. Furthermore, in this Progress Report we extend our work on ultrasonic beam profile issues through investigation of the phase fronts of the pressure field. In Section H of this Progress Report we briefly describe the experimental arrangement and methods for data acquisition of the ultrasonic diffraction patterns upon transmission through a thin woven composite. Section III details the analysis of the experimental data followed by the experimental results in Section IV. Finally, a discussion of the observations and conclusions is found in Section V.

Analysis on composition rules of Chinese patent drugs treating pain-related diseases based on data mining method.

PubMed

Tang, Shi-Huan; Shen, Dan; Yang, Hong-Jun

2017-08-24

To analyze the composition rules of oral prescriptions in the treatment of headache, stomachache and dysmenorrhea recorded in National Standard for Chinese Patent Drugs (NSCPD) enacted by Ministry of Public Health of China and then make comparison between them to better understand pain treatment in different regions of human body. Constructed NSCPD database had been constructed in 2014. Prescriptions treating the three pain-related diseases were searched and screened from the database. Then data mining method such as association rules analysis and complex system entropy method integrated in the data mining software Traditional Chinese Medicine Inheritance Support System (TCMISS) were applied to process the data. Top 25 drugs with high frequency in the treatment of each disease were selected, and 51, 33 and 22 core combinations treating headache, stomachache and dysmenorrhea respectively were mined out as well. The composition rules of the oral prescriptions for treating headache, stomachache and dysmenorrhea recorded in NSCPD has been summarized. Although there were similarities between them, formula varied according to different locations of pain. It can serve as an evidence and reference for clinical treatment and new drug development.

Extraction of the essential oil from endemic Origanum bilgeri P.H.Davis with two different methods: comparison of the oil composition and antibacterial activity.

PubMed

Sözmen, Fazli; Uysal, Burcu; Köse, Elif Odabaş; Aktaş, Ozgür; Cinbilgel, Ilker; Oksal, Birsen S

2012-07-01

The antibacterial activity and chemical composition of the essential oils (EOs) isolated from Origanum bilgeri P.H.Davis by two different extraction methods, i.e., hydrodistillation (HD) and solvent-free microwave extraction (SFME), were examined. This endemic Origanum species had shown very good antibacterial activity. The composition of the O. bilgeri EOs obtained by SFME and HD was investigated by GC/MS analysis. The main components of the oils obtained by both methods were carvacrol (90.20-84.30%), p-cymene (3.40-5.85%), γ-terpinene (0.47-1.20%), and thymol (0.69-1.08%). The EO isolation by SFME offered many important advantages, including a higher extraction yield, a shorter extraction time, and a higher content of the active component carvacrol. The carvacrol-rich oils obtained by both HD and SFME showed a good antibacterial activity. The largest inhibition zones were observed for the O. bilgeri EO obtained by SFME. Our study suggests that O. bilgeri EO has the potential to be used as preventative against bacterial contamination in many foods, instead of the common synthetic antimicrobial products. Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich.

ON EDGE CHIPPING TESTING AND SOME PERSONAL PERSPECTIVES ON THE STATE OF THE ART OF MECHANICAL TESTING

PubMed Central

Quinn, G. D.

2014-01-01

Objective The edge chipping test is used to measure the fracture resistance of dental restoration ceramics and resin composites. This paper focuses on the progress of evaluating chipping resistance of these materials and also on the progress of standardization of this test method. This paper also makes observations about the state of the art of mechanical testing of ceramic and composite restorative materials in general. Interlaboratory comparative studies (“round robins”) are recommended. Methods An edge chipping machine was used to evaluate dozens of materials including porcelains, glass ceramics, aluminas, zirconias, filled resin-composites, new hybrid ceramic-resin composites, laminated composite ceramics, and even polymethyl methacrylate based denture materials. Force versus distance data were collected over a broad range with different indenters. Several chipping resistance parameters were quantified. Results Older restorative materials such as feldspathic porcelains and veneering materials had limited chipping resistance, but more modern ceramics and filled composites show significant improvements. A yttria-partially stabilized zirconia had the greatest resistance to chipping. Much of the early work on edge chipping resistance of brittle materials emphasized linear force versus distance trends obtained with relatively blunt Rockwell C indenters. More recently, trends for dental restorative materials with alternative sharper indenters have been nonlinear. A new phenomenological model with a simple quadratic function fits all data exceptionally well. It is loosely based on an energy balance between indenter work and fracture and deformation energies in the chipped material. Significance Although a direct comparison of our laboratory scale tests on idealized simple geometries to clinical outcomes has not yet been done, anecdotal evidence suggests the procedure does produce clinically relevant rankings and outcomes. Despite the variations in the trends and indenters, comparisons between materials can easily be made by chipping convenient block-shaped specimens with sharp conical 120°, Vickers, or Rockwell C indenters at a defined edge distance of 0.5 mm. Broad distance ranges are recommended for trend evaluation. This work has provided important information for standardization. PMID:25244927

Design of a piezoelectric-based structural health monitoring system for damage detection in composite materials

NASA Astrophysics Data System (ADS)

Kessler, Seth S.; Spearing, S. Mark

2002-07-01

Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents the conclusions of an experimental and analytical survey of candidate methods for in-situ damage detection in composite structures. Experimental results are presented for the application of modal analysis and Lamb wave techniques to quasi-isotropic graphite/epoxy test specimens containing representative damage. Piezoelectric patches were used as actuators and sensors for both sets of experiments. Modal analysis methods were reliable for detecting small amounts of global damage in a simple composite structure. By comparison, Lamb wave methods were sensitive to all types of local damage present between the sensor and actuator, provided useful information about damage presence and severity, and present the possibility of estimating damage type and location. Analogous experiments were also performed for more complex built-up structures. These techniques are suitable for structural health monitoring applications since they can be applied with low power conformable sensors and can provide useful information about the state of a structure during operation. Piezoelectric patches could also be used as multipurpose sensors to detect damage by a variety of methods such as modal analysis, Lamb wave, acoustic emission and strain based methods simultaneously, by altering driving frequencies and sampling rates. This paper present guidelines and recommendations drawn from this research to assist in the design of a structural health monitoring system for a vehicle. These systems will be an important component in future designs of air and spacecraft to increase the feasibility of their missions.

ICP-MS analysis of lanthanide-doped nanoparticles as a non-radiative, multiplex approach to quantify biodistribution and blood clearance.

PubMed

Crayton, Samuel H; Elias, Drew R; Al Zaki, Ajlan; Cheng, Zhiliang; Tsourkas, Andrew

2012-02-01

Recent advances in material science and chemistry have led to the development of nanoparticles with diverse physicochemical properties, e.g. size, charge, shape, and surface chemistry. Evaluating which physicochemical properties are best for imaging and therapeutic studies is challenging not only because of the multitude of samples to evaluate, but also because of the large experimental variability associated with in vivo studies (e.g. differences in tumor size, injected dose, subject weight, etc.). To address this issue, we have developed a lanthanide-doped nanoparticle system and analytical method that allows for the quantitative comparison of multiple nanoparticle compositions simultaneously. Specifically, superparamagnetic iron oxide (SPIO) with a range of different sizes and charges were synthesized, each with a unique lanthanide dopant. Following the simultaneous injection of the various SPIO compositions into tumor-bearing mice, inductively coupled plasma mass spectroscopy (ICP-MS) was used to quantitatively and orthogonally assess the concentration of each SPIO composition in serial blood samples and the resected tumor and organs. The method proved generalizable to other nanoparticle platforms, including dendrimers, liposomes, and polymersomes. This approach provides a simple, cost-effective, and non-radiative method to quantitatively compare tumor localization, biodistribution, and blood clearance of more than 10 nanoparticle compositions simultaneously, removing subject-to-subject variability. Copyright © 2011 Elsevier Ltd. All rights reserved.

Comparison of air-displacement plethysmography with hydrostatic weighing and bioelectrical impedance analysis for the assessment of body composition in healthy adults.

PubMed

Biaggi, R R; Vollman, M W; Nies, M A; Brener, C E; Flakoll, P J; Levenhagen, D K; Sun, M; Karabulut, Z; Chen, K Y

1999-05-01

Over the past decade, considerable attention has been paid to accurately measuring body composition in diverse populations. Recently, the use of air-displacement plethysmography (AP) was proposed as an accurate, comfortable, and accessible method of body-composition analysis. The purpose of this study was to compare measurements of percentage body fat (%BF) by AP and 2 other established techniques, hydrostatic weighing (HW) and bioelectrical impedance analysis (BIA), in adults. The sample consisted of healthy men (n = 23) and women (n = 24). %BF was measured by AP, HW, and BIA. In the total group, %BF(AP) (25.0+/-8.9%) was not significantly different from %BF(HW) (25.1+/-7.7%) or %BF(BIA) (23.9+/-7.7%), and %BF(AP) was significantly correlated with %BF(HW) (r = 0.944, P < 0.001) and with %BF(BIA) (r = 0.859, P < 0.01). Compared with HW, AP underestimated %BF in men (by -1.24+/-3.12%) but overestimated %BF in women (by 1.02+/-2.48%), indicating a significant sex effect (P < 0.05). The differences in estimation between AP and BIA and between BIA and HW were not significantly different between the sexes. AP is an accurate method for assessing body composition in healthy adults. Future studies should assess further the cause of the individual variations with this new method.

Effects of temperature variations on guided waves propagating in composite structures

NASA Astrophysics Data System (ADS)

Shoja, Siavash; Berbyuk, Viktor; Boström, Anders

2016-04-01

Effects of temperature on guided waves propagating in composite materials is a well-known problem which has been investigated in many studies. The majority of the studies is focused on effects of high temperature. Understanding the effects of low temperature has major importance in composite structures and components which are operating in cold climate conditions such as e.g. wind turbines operating in cold climate regions. In this study first the effects of temperature variations on guided waves propagating in a composite plate is investigated experimentally in a cold climate chamber. The material is a common material used to manufacture rotor blades of wind turbines. The temperature range is 25°C to -25°C and effects of temperature variations on amplitude and phase shift of the received signal are investigated. In order to apply the effects of lowering the temperature on the received signal, the Baseline Signal Stretch (BSS) method is modified and used. The modification is based on decomposing the signal into symmetric and asymmetric modes and applying two different stretch factors on each of them. Finally the results obtained based on the new method is compared with the results of application of BSS with one stretch factor and experimental measurements. Comparisons show that an improvement is obtained using the BSS with the mode decomposition method at temperature variations of more than 25°C.

Solid rocket propellant waste disposal/ingredient recovery study

NASA Technical Reports Server (NTRS)

Mcintosh, M. J.

1976-01-01

A comparison of facility and operating costs of alternate methods shows open burning to be the lowest cost incineration method of waste propellant disposal. The selection, development, and implementation of an acceptable alternate is recommended. The recovery of ingredients from waste propellant has the probability of being able to pay its way, and even show a profit, when large consistent quantities of composite propellant are available. Ingredients recovered from space shuttle waste propellant would be worth over $1.5 million. Open and controlled burning are both energy wasteful.

Effect of Boundary Conditions on the Axial Compression Buckling of Homogeneous Orthotropic Composite Cylinders in the Long Column Range

NASA Technical Reports Server (NTRS)

Mikulas, Martin M., Jr.; Nemeth, Michael P.; Oremont, Leonard; Jegley, Dawn C.

2011-01-01

Buckling loads for long isotropic and laminated cylinders are calculated based on Euler, Fluegge and Donnell's equations. Results from these methods are presented using simple parameters useful for fundamental design work. Buckling loads for two types of simply supported boundary conditions are calculated using finite element methods for comparison to select cases of the closed form solution. Results indicate that relying on Donnell theory can result in an over-prediction of buckling loads by as much as 40% in isotropic materials.

Determining the slag fraction, water/binder ratio and degree of hydration in hardened cement pastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yio, M.H.N., E-mail: marcus.yio11@imperial.ac.uk; Phelan, J.C.; Wong, H.S.

2014-02-15

A method for determining the original mix composition of hardened slag-blended cement-based materials based on analysis of backscattered electron images combined with loss on ignition measurements is presented. The method does not require comparison to reference standards or prior knowledge of the composition of the binders used. Therefore, it is well-suited for application to real structures. The method is also able to calculate the degrees of reaction of slag and cement. Results obtained from an experimental study involving sixty samples with a wide range of water/binder (w/b) ratios (0.30 to 0.50), slag/binder ratios (0 to 0.6) and curing ages (3more » days to 1 year) show that the method is very promising. The mean absolute errors for the estimated slag, water and cement contents (kg/m{sup 3}), w/b and s/b ratios were 9.1%, 1.5%, 2.5%, 4.7% and 8.7%, respectively. 91% of the estimated w/b ratios were within 0.036 of the actual values. -- Highlights: •A new method for estimating w/b ratio and slag content in cement pastes is proposed. •The method is also able to calculate the degrees of reaction of slag and cement. •Reference standards or prior knowledge of the binder composition are not required. •The method was tested on samples with varying w/b ratios and slag content.« less

Comparison of two DSC-based methods to predict drug-polymer solubility.

PubMed

Rask, Malte Bille; Knopp, Matthias Manne; Olesen, Niels Erik; Holm, René; Rades, Thomas

2018-04-05

The aim of the present study was to compare two DSC-based methods to predict drug-polymer solubility (melting point depression method and recrystallization method) and propose a guideline for selecting the most suitable method based on physicochemical properties of both the drug and the polymer. Using the two methods, the solubilities of celecoxib, indomethacin, carbamazepine, and ritonavir in polyvinylpyrrolidone, hydroxypropyl methylcellulose, and Soluplus® were determined at elevated temperatures and extrapolated to room temperature using the Flory-Huggins model. For the melting point depression method, it was observed that a well-defined drug melting point was required in order to predict drug-polymer solubility, since the method is based on the depression of the melting point as a function of polymer content. In contrast to previous findings, it was possible to measure melting point depression up to 20 °C below the glass transition temperature (T g ) of the polymer for some systems. Nevertheless, in general it was possible to obtain solubility measurements at lower temperatures using polymers with a low T g . Finally, for the recrystallization method it was found that the experimental composition dependence of the T g must be differentiable for compositions ranging from 50 to 90% drug (w/w) so that one T g corresponds to only one composition. Based on these findings, a guideline for selecting the most suitable thermal method to predict drug-polymer solubility based on the physicochemical properties of the drug and polymer is suggested in the form of a decision tree. Copyright © 2018 Elsevier B.V. All rights reserved.

Body fatness or anthropometry for assessment of unhealthy weight status? Comparison between methods in South African children and adolescents.

PubMed

Craig, Eva; Reilly, John; Bland, Ruth

2013-11-01

A variety of methods are available for defining undernutrition (thinness/underweight/under-fat) and overnutrition (overweight/obesity/over-fat). The extent to which these definitions agree is unclear. The present cross-sectional study aimed to assess agreement between widely used methods of assessing nutritional status in children and adolescents, and to examine the benefit of body composition estimates. The main objective of the cross-sectional study was to assess underweight, overweight and obesity using four methods: (i) BMI-for-age using WHO (2007) reference data; (ii) BMI-for-age using Cole et al. and International Obesity Taskforce cut-offs; (iii) weight-for-age using the National Centre for Health Statistics/WHO growth reference 1977; and (iv) body fat percentage estimated by bio-impedance (body fat reference curves for children of McCarthy et al., 2006). Comparisons were made between methods using weighted kappa analyses. Rural South Africa. Individuals (n 1519) in three age groups (school grade 1, mean age 7 years; grade 5, mean age 11 years; grade 9, mean age 15 years). In boys, prevalence of unhealthy weight status (both under- and overnutrition) was much higher at all ages with body fatness measures than with simple anthropometric proxies for body fatness; agreement between fatness and weight-based measures was fair or slight using Landis and Koch categories. In girls, prevalence of unhealthy weight status was also higher with body fatness than with proxies, although agreement between measures ranged from fair to substantial. Methods for defining under- and overnutrition should not be considered equivalent. Weight-based measures provide highly conservative estimates of unhealthy weight status, possibly more conservative in boys. Simple body composition measures may be more informative than anthropometry for nutritional surveillance of children and adolescents.

Effect of whitening dentifrices on the surface roughness of a nanohybrid composite resin

PubMed Central

da Rosa, Gabriela Migliorin; da Silva, Luciana Mendonça; de Menezes, Márcio; do Vale, Hugo Felipe; Regalado, Diego Ferreira; Pontes, Danielson Guedes

2016-01-01

Objectives: The present study verified the influence of whitening dentifrices on the surface roughness of a nanohybrid composite resin. Materials and Methods: Thirty-two specimens were prepared with Filtek™ Z350 XT (3M/ESPE) and randomly divided into four groups (n = 08) that were subjected to brushing simulation equivalent to the period of 1 month. The groups assessed were a control group with distilled water (G1), Colgate Total 12 Professional Clean (G2), Sensodyne Extra Whitener Extra Fresh (G3), and Colgate Luminous White (G4). A sequence of 90 cycles was performed for all the samples. The initial roughness of each group was analyzed by the Surface Roughness Tester (TR 200-TIME Group Inc., CA, USA). After the brushing period, the final roughness was measured, and the results were statistically analyzed using nonparametric Kruskal–Wallis and Dunn tests for intergroup roughness comparison in the time factor. For intragroup and “Δ Final − Initial” comparisons, the Wilcoxon test and (one-way) ANOVA were, respectively, performed (α = 0.05). Results: The roughness mean values before and after brushing showed no statistically significant difference when the different dentifrices were used. None of the dentifrices analyzed increased significantly the nanohybrid composite resin surface roughness in a 1 month of tooth brushing simulation. Conclusions: These results suggest that no hazardous effect on the roughness of nanohybrid composite resin can be expected when whitening dentifrices are used for a short period. Similar studies should be conducted to analyze other esthetic composite materials. PMID:27095891

Nonlinear Analysis of Bonded Composite Tubular Lap Joints

NASA Technical Reports Server (NTRS)

Oterkus, E.; Madenci, E.; Smeltzer, S. S., III; Ambur, D. R.

2005-01-01

The present study describes a semi-analytical solution method for predicting the geometrically nonlinear response of a bonded composite tubular single-lap joint subjected to general loading conditions. The transverse shear and normal stresses in the adhesive as well as membrane stress resultants and bending moments in the adherends are determined using this method. The method utilizes the principle of virtual work in conjunction with nonlinear thin-shell theory to model the adherends and a cylindrical shear lag model to represent the kinematics of the thin adhesive layer between the adherends. The kinematic boundary conditions are imposed by employing the Lagrange multiplier method. In the solution procedure, the displacement components for the tubular joint are approximated in terms of non-periodic and periodic B-Spline functions in the longitudinal and circumferential directions, respectively. The approach presented herein represents a rapid-solution alternative to the finite element method. The solution method was validated by comparison against a previously considered tubular single-lap joint. The steep variation of both peeling and shearing stresses near the adhesive edges was successfully captured. The applicability of the present method was also demonstrated by considering tubular bonded lap-joints subjected to pure bending and torsion.

Composite fermions on a torus

NASA Astrophysics Data System (ADS)

Pu, Songyang; Wu, Ying-Hai; Jain, J. K.

2017-11-01

We achieve an explicit construction of the lowest Landau level (LLL) projected wave functions for composite fermions in the periodic (torus) geometry. To this end, we first demonstrate how the vortex attachment of the composite fermion (CF) theory can be accomplished in the torus geometry to produce the "unprojected" wave functions satisfying the correct (quasi)periodic boundary conditions. We then consider two methods for projecting these wave functions into the LLL. The direct projection produces valid wave functions but can be implemented only for very small systems. The more powerful and more useful projection method of Jain and Kamilla fails in the torus geometry because it does not preserve the periodic boundary conditions and thus takes us out of the original Hilbert space. We have succeeded in constructing a modified projection method that is consistent with both the periodic boundary conditions and the general structure of the CF theory. This method is valid for a large class of states of composite fermions, called "proper states," which includes the incompressible ground states at electron filling factors ν =n/2 p n +1 , their charged and neutral excitations, and also the quasidegenerate ground states at arbitrary filling factors of the form ν =ν/*2pν*+1 , where n and p are integers and ν* is the CF filling factor. Comparison with exact results known for small systems for the ground and excited states at filling factors ν =1 /3 , 2/5, and 3/7 demonstrates our LLL-projected wave functions to be extremely accurate representations of the actual Coulomb eigenstates. Our construction enables the study of large systems of composite fermions on the torus, thereby opening the possibility of investigating numerous interesting questions and phenomena.

Modeling of thermoplastic composites laser welding - A ray tracing method associated to thermal simulation

NASA Astrophysics Data System (ADS)

Dauphin, Myriam; Cosson, Benoit

2016-10-01

The importance of the absorption phenomenon occurring into the semi-transparent substrate of reinforced fiber thermoplastic, during the Laser Transmission Welding process (LTW), was examined. A (3D) transient thermal model of LTW was developed. First, the energy distribution coming from the laser irradiation was assessed. Ray tracing techniques allowed us to deal with both absorption and a strong light-scattering caused by the heterogeneity of composite. Then, the energy balance equation was solved in order to study the heating stage. This paper proposes a comparison of the welding area obtained with a model for which absorption was neglected and a second model where absorption was considered. The interest to consider absorption was shown for process optimization purposes and for the use of reinforced composites colored or filled with additives.

Fully Coupled Micro/Macro Deformation, Damage, and Failure Prediction for SiC/Ti-15-3 Laminates

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.; Lerch, Brad A.

2001-01-01

The deformation, failure, and low cycle fatigue life of SCS-6/Ti-15-3 composites are predicted using a coupled deformation and damage approach in the context of the analytical generalized method of cells (GMC) micromechanics model. The local effects of inelastic deformation, fiber breakage, fiber-matrix interfacial debonding, and fatigue damage are included as sub-models that operate on the micro scale for the individual composite phases. For the laminate analysis, lamination theory is employed as the global or structural scale model, while GMC is embedded to operate on the meso scale to simulate the behavior of the composite material within each laminate layer. While the analysis approach is quite complex and multifaceted, it is shown, through comparison with experimental data, to be quite accurate and realistic while remaining extremely efficient.

Enhanced antibactericidal function of W4+-doped titania-coated nickel ferrite composite nanoparticles: a biomaterial system.

PubMed

Sunkara, B K; Misra, R D K

2008-03-01

The study demonstrates a distinct enhancement of antimicrobial activity of W4+-doped titania that is coated on nickel ferrite nanoparticles in comparison to undoped titania. The composite nanoparticles were synthesized by uniquely combining reverse micelle and chemical hydrolysis synthesis methods [Rana S, Rawat J, Misra RDK, Acta Biomater 2005;1:691]. The superior antimicrobial activity of W4+-doped titania is related to the inhibition of electron-hole recombination and decrease in the band gap energy of titania. The function of the ferrite is to facilitate the removal of nanoparticles from the sprayed surface using a small magnetic field. The coating of ferrite nanoparticles with titania retains superparamagnetic character and magnetic strength of composite nanoparticles signifying non-deterioration of magnetic properties and promoting their use as removable antimicrobial photocatalyst nanoparticles.

An improved model for whole genome phylogenetic analysis by Fourier transform.

PubMed

Yin, Changchuan; Yau, Stephen S-T

2015-10-07

DNA sequence similarity comparison is one of the major steps in computational phylogenetic studies. The sequence comparison of closely related DNA sequences and genomes is usually performed by multiple sequence alignments (MSA). While the MSA method is accurate for some types of sequences, it may produce incorrect results when DNA sequences undergone rearrangements as in many bacterial and viral genomes. It is also limited by its computational complexity for comparing large volumes of data. Previously, we proposed an alignment-free method that exploits the full information contents of DNA sequences by Discrete Fourier Transform (DFT), but still with some limitations. Here, we present a significantly improved method for the similarity comparison of DNA sequences by DFT. In this method, we map DNA sequences into 2-dimensional (2D) numerical sequences and then apply DFT to transform the 2D numerical sequences into frequency domain. In the 2D mapping, the nucleotide composition of a DNA sequence is a determinant factor and the 2D mapping reduces the nucleotide composition bias in distance measure, and thus improving the similarity measure of DNA sequences. To compare the DFT power spectra of DNA sequences with different lengths, we propose an improved even scaling algorithm to extend shorter DFT power spectra to the longest length of the underlying sequences. After the DFT power spectra are evenly scaled, the spectra are in the same dimensionality of the Fourier frequency space, then the Euclidean distances of full Fourier power spectra of the DNA sequences are used as the dissimilarity metrics. The improved DFT method, with increased computational performance by 2D numerical representation, can be applicable to any DNA sequences of different length ranges. We assess the accuracy of the improved DFT similarity measure in hierarchical clustering of different DNA sequences including simulated and real datasets. The method yields accurate and reliable phylogenetic trees and demonstrates that the improved DFT dissimilarity measure is an efficient and effective similarity measure of DNA sequences. Due to its high efficiency and accuracy, the proposed DFT similarity measure is successfully applied on phylogenetic analysis for individual genes and large whole bacterial genomes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Comparison of the Debonding Characteristics of Conventional and New Debonding Instrument used for Ceramic, Composite and Metallic Brackets - An Invitro Study.

PubMed

Choudhary, Garima; Gill, Vikas; Reddy, Y N N; Sanadhya, Sudhanshu; Aapaliya, Pankaj; Sharma, Nidhi

2014-07-01

Debonding procedure is time consuming and damaging to the enamel if performed with improper technique. Various debonding methods include: the conventional methods that use pliers or wrenches, an ultrasonic method, electrothermal devices, air pressure impulse devices, diamond burs to grind the brackets off the tooth surface and lasers. Among all these methods, using debonding pliers is most convenient and effective method but has been reported to cause damage to the teeth. Recently, a New Debonding Instrument designed specifically for ceramic and composite brackets has been introduced. As this is a new instrument, little information is available on efficacy of this instrument. The purpose of this study was to evaluate the debonding characteristics of both "the conventional debonding Pliers" and "the New debonding instrument" when removing ceramic, composite and metallic brackets. One Hundred Thirty eight extracted maxillary premolar teeth were collected and divided into two Groups: Group A and Group B (n = 69) respectively. They were further divided into 3 subGroups (n = 23) each according to the types of brackets to be bonded. In subGroups A1 and B1{stainless steel};A2 and B2{ceramic};A3 and B3{composite}adhesive precoated maxillary premolar brackets were used. Among them {ceramic and composite} adhesive pre-coated maxillary premolar brackets were bonded. All the teeth were etched using 37% phosphoric acid for 15 seconds and the brackets were bonded using Transbond XT primer. Brackets were debonded using Conventional Debonding Plier and New Debonding Instrument (Group B). After debonding, the enamel surface of each tooth was examined under stereo microscope (10X magnifications). Amodifiedadhesive remnant index (ARI) was used to quantify the amount of remaining adhesive on each tooth. The observations demonstrate that the results of New Debonding Instrument for debonding of metal, ceramic and composite brackets were statistically significantly different (p = 0.04) and superior from the results of conventional debonding Pliers. The debonding efficiency of New Debonding Instrument is better than the debonding efficiency of Conventional Debonding Pliers for use of metal, ceramic and composite brackets respectively.

How School Healthy Is Your State? a State-by-State Comparison of School Health Practices Related to a Healthy School Environment and Health Education

ERIC Educational Resources Information Center

Brener, Nancy D.; Wechsler, Howell; McManus, Tim

2013-01-01

Background: School Health Profiles (Profiles) results help states understand how they compare to each other on specific school health policies and practices. The purpose of this study was to develop composite measures of critical Profiles results and use them to rate each state on their overall performance. Methods: Using data from state Profiles…

Effect of ecological surface treatment method on friction strength properties of nettle (urtica dioica) fibre yarns

NASA Astrophysics Data System (ADS)

Şansal, S.; Mıstık, S. I.; Fettahov, R.; Ovalı, S.; Duman, M.

2017-10-01

Over the last few decades, more attention is given to lignocellulose based fibres as reinforcement material in the polymer composites owing to the environmental pollution caused by the extensive usage of synthetic and inorganic fibres. Developing new natural fibre reinforced composites is the focus of many researches nowadays. They are made from renewable resources and they have less environmental effect in comparison to inorganic fibre reinforced composites. The interest of consumers in eco-friendly natural fibres and textiles has increased in recent years. Unlike inorganic fibres, natural fibres present light weight, high strength/density ratio and are readily available, environmentally friendly and biodegradable. Many different types of natural fibres are exploited for the production of biodegradable polymer composites. The nettle (Urtica dioica L.) is a well-known plant growing on rural sites of Europe, Asia, and North America. Nettle plant contains fibre similar to hemp and flax. However, similar to other natural fibres, nettle fibres are poorly compatible with the thermoplastic matrix of composites, due to their hydrophilic character which reduces mechanical properties of nettle fibre reinforced thermoplastics. In order to improve the fibrematrix adhesion of the natural fibre reinforced composites, surface treatment processes are applied to the lignocellulose fibres. In this study nettle (urtica dioica) fibre yarns were treated with NaOH by using conventional, ultrasonic and microwave energy methods. After treatment processes tensile strength, elongation, friction strength and SEM observations of the nettle fibre yarns were investigated. All treatment processes were improved the tensile strength, elongation and friction strength properties of the nettle fibre yarns. Also higher tensile strength, elongation and friction strength properties were obtained from treated nettle fibre yarns which treated by using microwave energy method.

The effect of silica-coating by sol-gel process on resin-zirconia bonding.

PubMed

Lung, Christie Ying Kei; Kukk, Edwin; Matinlinna, Jukka Pekka

2013-01-01

The effect of silica-coating by sol-gel process on the bond strength of resin composite to zirconia was evaluated and compared against the sandblasting method. Four groups of zirconia samples were silica-coated by sol-gel process under varied reagent ratios of ethanol, water, ammonia and tetraethyl orthosilicate and for different deposition times. One control group of zirconia samples were treated with sandblasting. Within each of these five groups, one subgroup of samples was kept in dry storage while another subgroup was aged by thermocycling for 6,000 times. Besides shear bond testing, the surface topography and surface elemental composition of silica-coated zirconia samples were also examined using scanning electron microscopy and X-ray photoelectron spectroscopy. Comparison of silica coating methods revealed significant differences in bond strength among the Dry groups (p<0.001) and Thermocycled groups (p<0.001). Comparison of sol-gel deposition times also revealed significant differences in bond strength among the Dry groups (p<0.01) and Thermocycled groups (p<0.001). Highest bond strengths were obtained after 141-h deposition: Dry (7.97±3.72 MPa); Thermocycled (2.33±0.79 MPa). It was concluded that silica-coating of zirconia by sol-gel process resulted in weaker resin bonding than by sandblasting.

High-precision isotopic characterization of USGS reference materials by TIMS and MC-ICP-MS

NASA Astrophysics Data System (ADS)

Weis, Dominique; Kieffer, Bruno; Maerschalk, Claude; Barling, Jane; de Jong, Jeroen; Williams, Gwen A.; Hanano, Diane; Pretorius, Wilma; Mattielli, Nadine; Scoates, James S.; Goolaerts, Arnaud; Friedman, Richard M.; Mahoney, J. Brian

2006-08-01

The Pacific Centre for Isotopic and Geochemical Research (PCIGR) at the University of British Columbia has undertaken a systematic analysis of the isotopic (Sr, Nd, and Pb) compositions and concentrations of a broad compositional range of U.S. Geological Survey (USGS) reference materials, including basalt (BCR-1, 2; BHVO-1, 2), andesite (AGV-1, 2), rhyolite (RGM-1, 2), syenite (STM-1, 2), granodiorite (GSP-2), and granite (G-2, 3). USGS rock reference materials are geochemically well characterized, but there is neither a systematic methodology nor a database for radiogenic isotopic compositions, even for the widely used BCR-1. This investigation represents the first comprehensive, systematic analysis of the isotopic composition and concentration of USGS reference materials and provides an important database for the isotopic community. In addition, the range of equipment at the PCIGR, including a Nu Instruments Plasma MC-ICP-MS, a Thermo Finnigan Triton TIMS, and a Thermo Finnigan Element2 HR-ICP-MS, permits an assessment and comparison of the precision and accuracy of isotopic analyses determined by both the TIMS and MC-ICP-MS methods (e.g., Nd isotopic compositions). For each of the reference materials, 5 to 10 complete replicate analyses provide coherent isotopic results, all with external precision below 30 ppm (2 SD) for Sr and Nd isotopic compositions (27 and 24 ppm for TIMS and MC-ICP-MS, respectively). Our results also show that the first- and second-generation USGS reference materials have homogeneous Sr and Nd isotopic compositions. Nd isotopic compositions by MC-ICP-MS and TIMS agree to within 15 ppm for all reference materials. Interlaboratory MC-ICP-MS comparisons show excellent agreement for Pb isotopic compositions; however, the reproducibility is not as good as for Sr and Nd. A careful, sequential leaching experiment of three first- and second-generation reference materials (BCR, BHVO, AGV) indicates that the heterogeneity in Pb isotopic compositions, and concentrations, could be directly related to contamination by the steel (mortar/pestle) used to process the materials. Contamination also accounts for the high concentrations of certain other trace elements (e.g., Li, Mo, Cd, Sn, Sb, W) in various USGS reference materials.

Effect of DNA Extraction Methods and Sampling Techniques on the Apparent Structure of Cow and Sheep Rumen Microbial Communities

PubMed Central

Henderson, Gemma; Cox, Faith; Kittelmann, Sandra; Miri, Vahideh Heidarian; Zethof, Michael; Noel, Samantha J.; Waghorn, Garry C.; Janssen, Peter H.

2013-01-01

Molecular microbial ecology techniques are widely used to study the composition of the rumen microbiota and to increase understanding of the roles they play. Therefore, sampling and DNA extraction methods that result in adequate yields of microbial DNA that also accurately represents the microbial community are crucial. Fifteen different methods were used to extract DNA from cow and sheep rumen samples. The DNA yield and quality, and its suitability for downstream PCR amplifications varied considerably, depending on the DNA extraction method used. DNA extracts from nine extraction methods that passed these first quality criteria were evaluated further by quantitative PCR enumeration of microbial marker loci. Absolute microbial numbers, determined on the same rumen samples, differed by more than 100-fold, depending on the DNA extraction method used. The apparent compositions of the archaeal, bacterial, ciliate protozoal, and fungal communities in identical rumen samples were assessed using 454 Titanium pyrosequencing. Significant differences in microbial community composition were observed between extraction methods, for example in the relative abundances of members of the phyla Bacteroidetes and Firmicutes. Microbial communities in parallel samples collected from cows by oral stomach-tubing or through a rumen fistula, and in liquid and solid rumen digesta fractions, were compared using one of the DNA extraction methods. Community representations were generally similar, regardless of the rumen sampling technique used, but significant differences in the abundances of some microbial taxa such as the Clostridiales and the Methanobrevibacter ruminantium clade were observed. The apparent microbial community composition differed between rumen sample fractions, and Prevotellaceae were most abundant in the liquid fraction. DNA extraction methods that involved phenol-chloroform extraction and mechanical lysis steps tended to be more comparable. However, comparison of data from studies in which different sampling techniques, different rumen sample fractions or different DNA extraction methods were used should be avoided. PMID:24040342

Effect of DNA extraction methods and sampling techniques on the apparent structure of cow and sheep rumen microbial communities.

PubMed

Henderson, Gemma; Cox, Faith; Kittelmann, Sandra; Miri, Vahideh Heidarian; Zethof, Michael; Noel, Samantha J; Waghorn, Garry C; Janssen, Peter H

2013-01-01

Molecular microbial ecology techniques are widely used to study the composition of the rumen microbiota and to increase understanding of the roles they play. Therefore, sampling and DNA extraction methods that result in adequate yields of microbial DNA that also accurately represents the microbial community are crucial. Fifteen different methods were used to extract DNA from cow and sheep rumen samples. The DNA yield and quality, and its suitability for downstream PCR amplifications varied considerably, depending on the DNA extraction method used. DNA extracts from nine extraction methods that passed these first quality criteria were evaluated further by quantitative PCR enumeration of microbial marker loci. Absolute microbial numbers, determined on the same rumen samples, differed by more than 100-fold, depending on the DNA extraction method used. The apparent compositions of the archaeal, bacterial, ciliate protozoal, and fungal communities in identical rumen samples were assessed using 454 Titanium pyrosequencing. Significant differences in microbial community composition were observed between extraction methods, for example in the relative abundances of members of the phyla Bacteroidetes and Firmicutes. Microbial communities in parallel samples collected from cows by oral stomach-tubing or through a rumen fistula, and in liquid and solid rumen digesta fractions, were compared using one of the DNA extraction methods. Community representations were generally similar, regardless of the rumen sampling technique used, but significant differences in the abundances of some microbial taxa such as the Clostridiales and the Methanobrevibacter ruminantium clade were observed. The apparent microbial community composition differed between rumen sample fractions, and Prevotellaceae were most abundant in the liquid fraction. DNA extraction methods that involved phenol-chloroform extraction and mechanical lysis steps tended to be more comparable. However, comparison of data from studies in which different sampling techniques, different rumen sample fractions or different DNA extraction methods were used should be avoided.

Sampling methods for the study of volatile profile of PDO wine vinegars. A comparison using multivariate data analysis.

PubMed

Ríos-Reina, Rocío; Morales, M Lourdes; García-González, Diego L; Amigo, José M; Callejón, Raquel M

2018-03-01

High-quality wine vinegars have been registered in Spain under protected designation of origin (PDO): "Vinagre de Jerez", "Vinagre de Condado de Huelva" and "Vinagre de Montilla-Moriles". The raw material, production and aging processes determine their quality and their aromatic composition. Vinegar volatile profile is usually analyzed by gas chromatography-mass spectrometry (GC-MS), being necessary a previous extraction step. Thus, three different sampling methods (Headspace solid phase microextraction "HS-SPME", Headspace stir bar sorptive extraction "HSSE" and Dynamic headspace extraction "DHS") were studied for the analysis of the volatile composition of Spanish PDO wine vinegars. Multivariate curve resolution (MCR) was used to solve chromatographic problems, improving the results obtained. Principal component analysis (PCA) showed that not all the sampling methods were equally suitable for the characterization and differentiation between PDOs and categories, being HSSE the technique that made able the best vinegar characterization. Copyright © 2017 Elsevier Ltd. All rights reserved.

Application of denaturing high-performance liquid chromatography (DHPLC) for the identification of fish: a new way to determine the composition of processed food containing multiple species.

PubMed

Le Fresne, Sophie; Popova, Milena; Le Vacon, Françoise; Carton, Thomas

2011-12-14

The identification of fish species in transformed food products is difficult because the existing methods are not adapted to heat-processed products containing more than one species. Using a common to all vertebrates region of the cytochrome b gene, we have developed a denaturing high-performance liquid chromatography (DHPLC) fingerprinting method, which allowed us to identify most of the species in commercial crab sticks. Whole fish and fillets were used for the creation of a library of referent DHPLC profiles. Crab sticks generated complex DHPLC profiles in which the number of contained fish species can be estimated by the number of major fluorescence peaks. The identity of some of the species was predicted by comparison of the peaks with the referent profiles, and others were identified after collection of the peak fractions, reamplification, and sequencing. DHPLC appears to be a quick and efficient method to analyze the species composition of complex heat-processed fish products.

Benchmarking FEniCS for mantle convection simulations

NASA Astrophysics Data System (ADS)

Vynnytska, L.; Rognes, M. E.; Clark, S. R.

2013-01-01

This paper evaluates the usability of the FEniCS Project for mantle convection simulations by numerical comparison to three established benchmarks. The benchmark problems all concern convection processes in an incompressible fluid induced by temperature or composition variations, and cover three cases: (i) steady-state convection with depth- and temperature-dependent viscosity, (ii) time-dependent convection with constant viscosity and internal heating, and (iii) a Rayleigh-Taylor instability. These problems are modeled by the Stokes equations for the fluid and advection-diffusion equations for the temperature and composition. The FEniCS Project provides a novel platform for the automated solution of differential equations by finite element methods. In particular, it offers a significant flexibility with regard to modeling and numerical discretization choices; we have here used a discontinuous Galerkin method for the numerical solution of the advection-diffusion equations. Our numerical results are in agreement with the benchmarks, and demonstrate the applicability of both the discontinuous Galerkin method and FEniCS for such applications.

Anticorrosion efficiency of ultrasonically deposited silica coatings on titanium

NASA Astrophysics Data System (ADS)

Ertaş, Fatma Sinem; Kaş, Recep; Mikó, Annamária; Birer, Özgür

2013-07-01

We utilized high intensity ultrasound to prepare coatings of silica and organically modified silica composed of multiple layers of densely packed nanoparticles. Ultrasound was used to collide nanoparticles onto an activated titanium surface with high speed. Large areas could be homogeneously coated by this method. These coatings were characterized by spectroscopy and microscopy methods and the anticorrosion efficiency in NaCl solution was evaluated by electrochemical measurements. The results indicated that the composite coatings provided good quality barrier layer on bare titanium and decreased the anodic corrosion rate. It was found that increase in the organic content of the coating shifted the passivation potential towards more positive direction. The comparison of the impedance results recorded at the corrosion potential pointed out that in each case a good quality barrier layer was formed on the titanium surface. The outstanding corrosion resistance of the composite coatings with only ~200 nm thickness shows that ultrasound assisted deposition can be a competitive method to obtain corrosion protective layers.

Validation of Skeletal Muscle cis-Regulatory Module Predictions Reveals Nucleotide Composition Bias in Functional Enhancers

PubMed Central

Kwon, Andrew T.; Chou, Alice Yi; Arenillas, David J.; Wasserman, Wyeth W.

2011-01-01

We performed a genome-wide scan for muscle-specific cis-regulatory modules (CRMs) using three computational prediction programs. Based on the predictions, 339 candidate CRMs were tested in cell culture with NIH3T3 fibroblasts and C2C12 myoblasts for capacity to direct selective reporter gene expression to differentiated C2C12 myotubes. A subset of 19 CRMs validated as functional in the assay. The rate of predictive success reveals striking limitations of computational regulatory sequence analysis methods for CRM discovery. Motif-based methods performed no better than predictions based only on sequence conservation. Analysis of the properties of the functional sequences relative to inactive sequences identifies nucleotide sequence composition can be an important characteristic to incorporate in future methods for improved predictive specificity. Muscle-related TFBSs predicted within the functional sequences display greater sequence conservation than non-TFBS flanking regions. Comparison with recent MyoD and histone modification ChIP-Seq data supports the validity of the functional regions. PMID:22144875

Depth-resolved sample composition analysis using laser-induced ablation-quadrupole mass spectrometry and laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Oelmann, J.; Gierse, N.; Li, C.; Brezinsek, S.; Zlobinski, M.; Turan, B.; Haas, S.; Linsmeier, Ch.

2018-06-01

Monitoring a sample's material composition became more and more important over the last years for both - industrial process control as well as for post mortem analysis in research and industrial development. Although material composition identification as well as a comparison with standard samples works fine, there is a lack of diagnostics which can provide quantitative information with depth resolution without any standard samples. We present a novel method utilizing a residual gas analysis with quadrupole mass spectrometry after picosecond laser-induced ablation and release of volatile species. In the present experiment, well characterized multilayer thin film solar cells (μc-Si:H and a-Si:D as p-i-n-junctions on ZnO:Al electrodes) are used as a set of well characterized material samples to demonstrate the capabilities of the new method. The linearity of the spectrometer signal to gas pressure simplifies its calibration and reduces its uncertainties in comparison with other analysis techniques, although high vacuum conditions (10-6 hPa to 10-7 hPa) are required to reach high sensitivity better than the percent-range. Moreover, the laser-ablation based sample analysis requires no preparation of the sample and is flexible regarding ablation rates. The application of a picosecond laser pulse ensures that the thermal penetration depth of the laser is in the same order of magnitude as the ablation rate, which enables to achieve depth resolutions in the order of 100 nm and avoids matrix mixing effects at the edge of the laser-induced crater in the sample.

Features of Different Inorganic Scintillators Used in Neutron-Radiation Systems for Illegal Substance Detection

NASA Astrophysics Data System (ADS)

Batyaev, V. F.; Belichenko, S. G.; Bestaev, R. R.

2016-04-01

The work is devoted to a quantitative comparison of different inorganic scintillators to be used in neutron-radiation inspection systems. Such systems can be based on the tagged neutron (TN) method and have a significant potential in different applications such as detection of explosives, drugs, mines, identification of chemical warfare agents, assay of nuclear materials and human body composition [1]-[3]. The elemental composition of an inspected object is determined via spectrometry of gammas from the object bombarded by neutrons which are tagged by an alpha-detector built inside a neutron generator. This creates a task to find a quantitative indicator of the object identification quality (via elemental composition) as a function of basic parameters of the γ-detectors, such as their efficiency, energy and time resolutions, which in turn are generally defined by a scintillator of the detector. We have tried to solve the task for a set of four scintillators which are often used in the study of TN method, namely BGO, LaBr3, LYSO, NaI(Tl), whose basic parameters are well known [4]-[7].

Computational Homogenization of Mechanical Properties for Laminate Composites Reinforced with Thin Film Made of Carbon Nanotubes

NASA Astrophysics Data System (ADS)

El Moumen, A.; Tarfaoui, M.; Lafdi, K.

2018-06-01

Elastic properties of laminate composites based Carbone Nanotubes (CNTs), used in military applications, were estimated using homogenization techniques and compared to the experimental data. The composite consists of three phases: T300 6k carbon fibers fabric with 5HS (satin) weave, baseline pure Epoxy matrix and CNTs added with 0.5%, 1%, 2% and 4%. Two step homogenization methods based RVE model were employed. The objective of this paper is to determine the elastic properties of structure starting from the knowledge of those of constituents (CNTs, Epoxy and carbon fibers fabric). It is assumed that the composites have a geometric periodicity and the homogenization model can be represented by a representative volume element (RVE). For multi-scale analysis, finite element modeling of unit cell based two step homogenization method is used. The first step gives the properties of thin film made of epoxy and CNTs and the second is used for homogenization of laminate composite. The fabric unit cell is chosen using a set of microscopic observation and then identified by its ability to enclose the characteristic periodic repeat in the fabric weave. The unit cell model of 5-Harness satin weave fabric textile composite is identified for numerical approach and their dimensions are chosen based on some microstructural measurements. Finally, a good comparison was obtained between the predicted elastic properties using numerical homogenization approach and the obtained experimental data with experimental tests.

Computational Homogenization of Mechanical Properties for Laminate Composites Reinforced with Thin Film Made of Carbon Nanotubes

NASA Astrophysics Data System (ADS)

El Moumen, A.; Tarfaoui, M.; Lafdi, K.

2017-08-01

Elastic properties of laminate composites based Carbone Nanotubes (CNTs), used in military applications, were estimated using homogenization techniques and compared to the experimental data. The composite consists of three phases: T300 6k carbon fibers fabric with 5HS (satin) weave, baseline pure Epoxy matrix and CNTs added with 0.5%, 1%, 2% and 4%. Two step homogenization methods based RVE model were employed. The objective of this paper is to determine the elastic properties of structure starting from the knowledge of those of constituents (CNTs, Epoxy and carbon fibers fabric). It is assumed that the composites have a geometric periodicity and the homogenization model can be represented by a representative volume element (RVE). For multi-scale analysis, finite element modeling of unit cell based two step homogenization method is used. The first step gives the properties of thin film made of epoxy and CNTs and the second is used for homogenization of laminate composite. The fabric unit cell is chosen using a set of microscopic observation and then identified by its ability to enclose the characteristic periodic repeat in the fabric weave. The unit cell model of 5-Harness satin weave fabric textile composite is identified for numerical approach and their dimensions are chosen based on some microstructural measurements. Finally, a good comparison was obtained between the predicted elastic properties using numerical homogenization approach and the obtained experimental data with experimental tests.

Derivation of Aerosol Columnar Mass from MODIS Optical Depth

NASA Technical Reports Server (NTRS)

Gasso, Santiago; Hegg, Dean A.

2003-01-01

In order to verify performance, aerosol transport models (ATM) compare aerosol columnar mass (ACM) with those derived from satellite measurements. The comparison is inherently indirect since satellites derive optical depths and they use a proportionality constant to derive the ACM. Analogously, ATMs output a four dimensional ACM distribution and the optical depth is linearly derived. In both cases, the proportionality constant requires a direct intervention of the user by prescribing the aerosol composition and size distribution. This study introduces a method that minimizes the direct user intervention by making use of the new aerosol products of MODIS. A parameterization is introduced for the derivation of columnar aerosol mass (AMC) and CCN concentration (CCNC) and comparisons between sunphotometer, MODIS Airborne Simulator (MAS) and in-measurements are shown. The method still relies on the scaling between AMC and optical depth but the proportionality constant is dependent on the MODIS derived r$_{eff}$,\\eta (contribution of the accumulation mode radiance to the total radiance), ambient RH and an assumed constant aerosol composition. The CCNC is derived fkom a recent parameterization of CCNC as a function of the retrieved aerosol volume. By comparing with in-situ data (ACE-2 and TARFOX campaigns), it is shown that retrievals in dry ambient conditions (dust) are improved when using a proportionality constant dependent on r$ {eff}$ and \\eta derived in the same pixel. In high humidity environments, the improvement inthe new method is inconclusive because of the difficulty in accounting for the uneven vertical distribution of relative humidity. Additionally, two detailed comparisons of AMC and CCNC retrieved by the MAS algorithm and the new method are shown. The new method and MAS retrievals of AMC are within the same order of magnitude with respect to the in-situ measurements of aerosol mass. However, the proposed method is closer to the in-situ measurements than the MODIS retrievals. The retrievals of CCNC are also within the same order of magnitude for both methods. The new method is applied to an actual MODIS retrieval and although no in-situ data is available to compare, it is shown that the proposed method yields more credible values than the MODIS retrievals. In addition, recent data available from the PRIDE (Puerto Rico Dust Experiment, July 2000) will be shown by comparing sunphotometer, MODIS and in-situ data.

Lamb wave dispersion and anisotropy profiling of composite plates via non-contact air-coupled and laser ultrasound

NASA Astrophysics Data System (ADS)

Harb, M. S.; Yuan, F. G.

2015-03-01

Conventional ultrasound inspection has been a standard non-destructive testing method for providing an in-service evaluation and noninvasive means of probing the interior of a structure. In particular, measurement of the propagation characteristics of Lamb waves allows inspection of plates that are typical components in aerospace industry. A rapid, complete non-contact hybrid approach for excitation and detection of Lamb waves is presented and applied for non-destructive evaluation of composites. An air-coupled transducer (ACT) excites ultrasonic waves on the surface of a composite plate, generating different propagating Lamb wave modes and a laser Doppler vibrometer (LDV) is used to measure the out-of-plane velocity of the plate. This technology, based on direct waveform imaging, focuses on measuring dispersive curves for A0 mode in a composite laminate and its anisotropy. A two-dimensional fast Fourier transform (2D-FFT) is applied to out-of-plane velocity data captured experimentally using LDV to go from the time-spatial domain to frequency-wavenumber domain. The result is a 2D array of amplitudes at discrete frequencies and wavenumbers for A0 mode in a given propagation direction along the composite. The peak values of the curve are then used to construct frequency wavenumber and phase velocity dispersion curves, which are also obtained directly using Snell's law and the incident angle of the excited ultrasonic waves. A high resolution and strong correlation between numerical and experimental results are observed for dispersive curves with Snell's law method in comparison to 2D-FFT method. Dispersion curves as well as velocity curves for the composite plate along different directions of wave propagation are measured. The visual read-out of the dispersion curves at different propagation directions as well as the phase velocity curves provide profiling and measurements of the composite anisotropy. The results proved a high sensitivity of the air-coupled and laser ultrasound technique in non-contact characterization of Lamb wave dispersion and material anisotropy of composite plates using simple Snell's law method.

Final report on EURAMET.QM-S6/1195: Bilateral comparison of liquefied hydrocarbon mixtures in constant pressure (piston) cylinders

NASA Astrophysics Data System (ADS)

Brown, Andrew S.; Downey, Michael L.; Milton, Martin J. T.; van der Veen, Adriaan M. H.; Zalewska, Ewelina T.; Li, Jianrong

2013-01-01

Traceable liquid hydrocarbon mixtures are required in order to underpin measurements of the composition and other physical properties of LPG (liquefied petroleum gas) and LNG (liquefied natural gas), thus meeting the needs of an increasingly large European industrial market. The development of traceable liquid hydrocarbon standards by National Measurement Institutes (NMIs) was still at a relatively early stage at the time this comparison was proposed in 2011. NPL and VSL, who were the only NMIs active in this area, had developed methods for the preparation and analysis of such standards in constant pressure (piston) cylinders, but neither laboratory had Calibration and Measurement Capabilities (CMCs) for these mixtures. This report presents the results of EURAMET 1195, the first comparison of liquid hydrocarbon mixtures between NMIs, which assessed the preparation and analytical capabilities of NPL and VSL for these mixtures. The comparison operated between August 2011 and January 2012. Each laboratory prepared a liquid hydrocarbon standard with nominally the same composition and these standards were exchanged for analysis. The results of the comparison show a good agreement between the laboratories' results and the comparison reference values for the six components with amount fractions greater than 1.0 cmol/mol (propane, propene, iso-butene, n-butane, iso-butane and 1-butene). Measurement of the three components with lower amount fractions (1,3-butadiene, iso-pentane and n-pentane) proved more challenging. In all but one case, the differences from the comparison reference values for these three components were greater than the expanded measurement uncertainty. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Laser-induced breakdown spectroscopy (LIBS) technique for the determination of the chemical composition of complex inorganic materials

NASA Astrophysics Data System (ADS)

Łazarek, Łukasz; Antończak, Arkadiusz J.; Wójcik, Michał R.; Kozioł, Paweł E.; Stepak, Bogusz; Abramski, Krzysztof M.

2014-08-01

Laser-induced breakdown spectroscopy (LIBS) is a fast, fully optical method, that needs little or no sample preparation. In this technique qualitative and quantitative analysis is based on comparison. The determination of composition is generally based on the construction of a calibration curve namely the LIBS signal versus the concentration of the analyte. Typically, to calibrate the system, certified reference materials with known elemental composition are used. Nevertheless, such samples due to differences in the overall composition with respect to the used complex inorganic materials can influence significantly on the accuracy. There are also some intermediate factors which can cause imprecision in measurements, such as optical absorption, surface structure, thermal conductivity etc. This paper presents the calibration procedure performed with especially prepared pellets from the tested materials, which composition was previously defined. We also proposed methods of post-processing which allowed for mitigation of the matrix effects and for a reliable and accurate analysis. This technique was implemented for determination of trace elements in industrial copper concentrates standardized by conventional atomic absorption spectroscopy with a flame atomizer. A series of copper flotation concentrate samples was analyzed for contents of three elements, that is silver, cobalt and vanadium. It has been shown that the described technique can be used to qualitative and quantitative analyses of complex inorganic materials, such as copper flotation concentrates.

Surface tension and density of liquid In-Sn-Zn alloys

NASA Astrophysics Data System (ADS)

Pstruś, Janusz

2013-01-01

Using the dilatometric method, measurements of the density of liquid alloys of the ternary system In-Sn-Zn in four sections with a constant ratio Sn:In = 24:1, 3:1, 1:1, 1:3, for various Zn additions (5, 10, 14, 20, 3 5, 50 and 75 at.% Zn) were performed at the temperature ranges of 500-1150 K. Density decreases linearly for all compositions. The molar volume calculated from density data exhibits close to ideal dependence on composition. Measurements of the surface tension of liquid alloys have been conducted using the method of maximum pressure in the gas bubbles. There were observed linear dependences on temperature with a negative gradients dσ/dT. Generally, with two exceptions, there was observed the increase of surface tension with increasing content of zinc. Using the Butler's model, the surface tension isotherms were calculated for temperatures T = 673 and 1073 K. Calculations show that only for high temperatures and for low content of zinc (up to about 35 at.%), the modeling is in very good agreement with experiment. Using the mentioned model, the composition of the surface phase was defined at two temperatures T = 673 and 973 K. Regardless of the temperature and of the defined section, the composition of the bulk is very different in comparison with the composition of the surface.

High-Resolution Melt Analysis for Rapid Comparison of Bacterial Community Compositions

PubMed Central

Hjelmsø, Mathis Hjort; Hansen, Lars Hestbjerg; Bælum, Jacob; Feld, Louise; Holben, William E.

2014-01-01

In the study of bacterial community composition, 16S rRNA gene amplicon sequencing is today among the preferred methods of analysis. The cost of nucleotide sequence analysis, including requisite computational and bioinformatic steps, however, takes up a large part of many research budgets. High-resolution melt (HRM) analysis is the study of the melt behavior of specific PCR products. Here we describe a novel high-throughput approach in which we used HRM analysis targeting the 16S rRNA gene to rapidly screen multiple complex samples for differences in bacterial community composition. We hypothesized that HRM analysis of amplified 16S rRNA genes from a soil ecosystem could be used as a screening tool to identify changes in bacterial community structure. This hypothesis was tested using a soil microcosm setup exposed to a total of six treatments representing different combinations of pesticide and fertilization treatments. The HRM analysis identified a shift in the bacterial community composition in two of the treatments, both including the soil fumigant Basamid GR. These results were confirmed with both denaturing gradient gel electrophoresis (DGGE) analysis and 454-based 16S rRNA gene amplicon sequencing. HRM analysis was shown to be a fast, high-throughput technique that can serve as an effective alternative to gel-based screening methods to monitor microbial community composition. PMID:24610853

On Multi-Objective Based Constitutive Modelling Methodology and Numerical Validation in Small-Hole Drilling of Al6063/SiCp Composites

PubMed Central

Xiang, Junfeng; Xie, Lijing; Gao, Feinong; Zhang, Yu; Yi, Jie; Wang, Tao; Pang, Siqin; Wang, Xibin

2018-01-01

Discrepancies in capturing material behavior of some materials, such as Particulate Reinforced Metal Matrix Composites, by using conventional ad hoc strategy make the applicability of Johnson-Cook constitutive model challenged. Despites applicable efforts, its extended formalism with more fitting parameters would increase the difficulty in identifying constitutive parameters. A weighted multi-objective strategy for identifying any constitutive formalism is developed to predict mechanical behavior in static and dynamic loading conditions equally well. These varying weighting is based on the Gaussian-distributed noise evaluation of experimentally obtained stress-strain data in quasi-static or dynamic mode. This universal method can be used to determine fast and directly whether the constitutive formalism is suitable to describe the material constitutive behavior by measuring goodness-of-fit. A quantitative comparison of different fitting strategies on identifying Al6063/SiCp’s material parameters is made in terms of performance evaluation including noise elimination, correlation, and reliability. Eventually, a three-dimensional (3D) FE model in small-hole drilling of Al6063/SiCp composites, using multi-objective identified constitutive formalism, is developed. Comparison with the experimental observations in thrust force, torque, and chip morphology provides valid evidence on the applicability of the developed multi-objective identification strategy in identifying constitutive parameters. PMID:29324688

FaceSheet Push-off Tests to Determine Composite Sandwich Toughness at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Gates, Thomas S.; Herring, Helen M.

2001-01-01

A new novel test method, associated analysis, and experimental procedures are developed to investigate the toughness of the facesheet-to-core interface of a sandwich material at cryogenic temperatures. The test method is designed to simulate the failure mode associated with facesheet debonding from high levels of gas pressure in the sandwich core. The effects of specimen orientation are considered, and the results of toughness measurements are presented. Comparisons are made between room and liquid nitrogen (-196 C) test temperatures. It was determined that the test method is insensitive to specimen facesheet orientation and strain energy release rate increases with a decrease in the test temperature.

A general panel sizing computer code and its application to composite structural panels

NASA Technical Reports Server (NTRS)

Anderson, M. S.; Stroud, W. J.

1978-01-01

A computer code for obtaining the dimensions of optimum (least mass) stiffened composite structural panels is described. The procedure, which is based on nonlinear mathematical programming and a rigorous buckling analysis, is applicable to general cross sections under general loading conditions causing buckling. A simplified method of accounting for bow-type imperfections is also included. Design studies in the form of structural efficiency charts for axial compression loading are made with the code for blade and hat stiffened panels. The effects on panel mass of imperfections, material strength limitations, and panel stiffness requirements are also examined. Comparisons with previously published experimental data show that accounting for imperfections improves correlation between theory and experiment.

Enhanced pinning in mixed rare earth-123 films

DOEpatents

Driscoll, Judith L [Los Alamos, NM; Foltyn, Stephen R [Los Alamos, NM

2009-06-16

An superconductive article and method of forming such an article is disclosed, the article including a substrate and a layer of a rare earth barium cuprate film upon the substrate, the rare earth barium cuprate film including two or more rare earth metals capable of yielding a superconductive composition where ion size variance between the two or more rare earth metals is characterized as greater than zero and less than about 10.times.10.sup.-4, and the rare earth barium cuprate film including two or more rare earth metals is further characterized as having an enhanced critical current density in comparison to a standard YBa.sub.2Cu.sub.3O.sub.y composition under identical testing conditions.

Comparison of the Compositions of the Stool Microbiotas of Infants Fed Goat Milk Formula, Cow Milk-Based Formula, or Breast Milk

PubMed Central

Lawley, Blair; Munro, Karen; Gowri Pathmanathan, Siva; Zhou, Shao J.; Makrides, Maria; Gibson, Robert A.; Sullivan, Thomas; Prosser, Colin G.; Lowry, Dianne; Hodgkinson, Alison J.

2013-01-01

The aim of the study was to compare the compositions of the fecal microbiotas of infants fed goat milk formula to those of infants fed cow milk formula or breast milk as the gold standard. Pyrosequencing of 16S rRNA gene sequences was used in the analysis of the microbiotas in stool samples collected from 90 Australian babies (30 in each group) at 2 months of age. Beta-diversity analysis of total microbiota sequences and Lachnospiraceae sequences revealed that they were more similar in breast milk/goat milk comparisons than in breast milk/cow milk comparisons. The Lachnospiraceae were mostly restricted to a single species (Ruminococcus gnavus) in breast milk-fed and goat milk-fed babies compared to a more diverse collection in cow milk-fed babies. Bifidobacteriaceae were abundant in the microbiotas of infants in all three groups. Bifidobacterium longum, Bifidobacterium breve, and Bifidobacterium bifidum were the most commonly detected bifidobacterial species. A semiquantitative PCR method was devised to differentiate between B. longum subsp. longum and B. longum subsp. infantis and was used to test stool samples. B. longum subsp. infantis was seldom present in stools, even of breast milk-fed babies. The presence of B. bifidum in the stools of breast milk-fed infants at abundances greater than 10% of the total microbiota was associated with the highest total abundances of Bifidobacteriaceae. When Bifidobacteriaceae abundance was low, Lachnospiraceae abundances were greater. New information about the composition of the fecal microbiota when goat milk formula is used in infant nutrition was thus obtained. PMID:23455335

Comparison of the compositions of the stool microbiotas of infants fed goat milk formula, cow milk-based formula, or breast milk.

PubMed

Tannock, Gerald W; Lawley, Blair; Munro, Karen; Gowri Pathmanathan, Siva; Zhou, Shao J; Makrides, Maria; Gibson, Robert A; Sullivan, Thomas; Prosser, Colin G; Lowry, Dianne; Hodgkinson, Alison J

2013-05-01

The aim of the study was to compare the compositions of the fecal microbiotas of infants fed goat milk formula to those of infants fed cow milk formula or breast milk as the gold standard. Pyrosequencing of 16S rRNA gene sequences was used in the analysis of the microbiotas in stool samples collected from 90 Australian babies (30 in each group) at 2 months of age. Beta-diversity analysis of total microbiota sequences and Lachnospiraceae sequences revealed that they were more similar in breast milk/goat milk comparisons than in breast milk/cow milk comparisons. The Lachnospiraceae were mostly restricted to a single species (Ruminococcus gnavus) in breast milk-fed and goat milk-fed babies compared to a more diverse collection in cow milk-fed babies. Bifidobacteriaceae were abundant in the microbiotas of infants in all three groups. Bifidobacterium longum, Bifidobacterium breve, and Bifidobacterium bifidum were the most commonly detected bifidobacterial species. A semiquantitative PCR method was devised to differentiate between B. longum subsp. longum and B. longum subsp. infantis and was used to test stool samples. B. longum subsp. infantis was seldom present in stools, even of breast milk-fed babies. The presence of B. bifidum in the stools of breast milk-fed infants at abundances greater than 10% of the total microbiota was associated with the highest total abundances of Bifidobacteriaceae. When Bifidobacteriaceae abundance was low, Lachnospiraceae abundances were greater. New information about the composition of the fecal microbiota when goat milk formula is used in infant nutrition was thus obtained.

Comparison of the lipid composition of oat root and coleoptile plasma membranes: lack of short-term change in response to auxin

NASA Technical Reports Server (NTRS)

Sandstrom, R. P.; Cleland, R. E.

1989-01-01

The total lipid composition of plasma membranes (PM), isolated by the phase partitioning method from two different oat (Avena sativa L.) tissues, the root and coleoptile, was compared. In general, the PM lipid composition was not conserved between these two organs of the oat seedling. Oat roots contained 50 mole percent phospholipid, 25 mole percent glycolipid, and 25 mole percent free sterol, whereas comparable amounts in the coleoptile were 42, 39, and 19 mole percent, respectively. Individual lipid components within each lipid class also showed large variations between the two tissues. Maximum specific ATPase activity in the root PM was more than double the activity in the coleoptile. Treatment of coleoptile with auxin for 1 hour resulted in no detectable changes in PM lipids or extractable ATPase activity. Differences in the PM lipid composition between the two tissues that may define the limits of ATPase activity are discussed.

Crystal-Chemical Analysis Martian Minerals in Gale Crater

NASA Technical Reports Server (NTRS)

Morrison, S. M.; Downs, R. T.; Blake, D. F.; Bish, D. L.; Ming, D. W.; Morris, R. V.; Yen, A. S.; Chipera, S. J.; Treiman, A. H.; Vaniman, D. T.;

Ultra High Temperature Ceramics' Processing Routes and Microstructures Compared

NASA Technical Reports Server (NTRS)

Gusman, Michael; Stackpoole, Mairead; Johnson, Sylvia; Gasch, Matt; Lau, Kai-Hung; Sanjurjo, Angel

2009-01-01

Ultra High Temperature Ceramics (UHTCs), such as HfB2 and ZrB2 composites containing SiC, are known to have good thermal shock resistance and high thermal conductivity at elevated temperatures. These UHTCs have been proposed for a number of structural applications in hypersonic vehicles, nozzles, and sharp leading edges. NASA Ames is working on controlling UHTC properties (especially, mechanical properties, thermal conductivity, and oxidation resistance) through processing, composition, and microstructure. In addition to using traditional methods of combining additives to boride powders, we are preparing UHTCs using coat ing powders to produce both borides and additives. These coatings and additions to the powders are used to manipulate and control grain-boundary composition and second- and third-phase variations within the UHTCs. Controlling the composition of high temperature oxidation by-products is also an important consideration. The powders are consolidated by hot-pressing or field-assisted sintering (FAS). Comparisons of microstructures and hardness data will be presented.

Preparation of ZnS/ZnO core - Shell nanocomposite and its photocatalytic behaviour for dye degradation

NASA Astrophysics Data System (ADS)

Patil, Bharati N.; Acharya, Smita A.

2018-05-01

In the present work ZnS-ZnO core-shell-type composite nanostructures was prepared by hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD) for structural confirmation. Microstructural study by scanning electron microscopy (SEM) exhibit nanoscale dimensions of as-synthesized composite. UV/VIS spectra were recorded for evaluation of photophysical properties. The composite was explored as photocatalysts to study dye degradation using methylene blue in aqueous slurry under irradiation of 663 nm wavelength and congo red under irradiation of 493 nm wavelength. Under the same conditions the photocatalytic activity of the individual phases ZnS and ZnO were also examined, just for sake of comparison. The ZnS-ZnO composite is found to be enhancing the rate of photo degradation of toxic dyes in presence of visible light as compared to ZnS and ZnO individual phases. Thus ZnS based metal sulphide/oxide semiconductor nanocomposites are potential material for Photo-degradation of toxic dyes, and act as good photocatalyst.

A global optimization algorithm for protein surface alignment

PubMed Central

2010-01-01

Background A relevant problem in drug design is the comparison and recognition of protein binding sites. Binding sites recognition is generally based on geometry often combined with physico-chemical properties of the site since the conformation, size and chemical composition of the protein surface are all relevant for the interaction with a specific ligand. Several matching strategies have been designed for the recognition of protein-ligand binding sites and of protein-protein interfaces but the problem cannot be considered solved. Results In this paper we propose a new method for local structural alignment of protein surfaces based on continuous global optimization techniques. Given the three-dimensional structures of two proteins, the method finds the isometric transformation (rotation plus translation) that best superimposes active regions of two structures. We draw our inspiration from the well-known Iterative Closest Point (ICP) method for three-dimensional (3D) shapes registration. Our main contribution is in the adoption of a controlled random search as a more efficient global optimization approach along with a new dissimilarity measure. The reported computational experience and comparison show viability of the proposed approach. Conclusions Our method performs well to detect similarity in binding sites when this in fact exists. In the future we plan to do a more comprehensive evaluation of the method by considering large datasets of non-redundant proteins and applying a clustering technique to the results of all comparisons to classify binding sites. PMID:20920230

Parametric study of guided waves dispersion curves for composite plates

NASA Astrophysics Data System (ADS)

Predoi, Mihai Valentin; Petre, Cristian Cǎtǎlin; Kettani, Mounsif Ech Cherif El; Leduc, Damien

2018-02-01

Nondestructive testing of composite panels benefit from the relatively long range propagation of guided waves in sandwich structures. The guided waves are sensitive to delamination, air bubbles inclusions and cracks and can thus bring information about hidden defects in the composite panel. The preliminary data in all such inspections is represented by the dispersion curves, representing the dependency of the phase/group velocity on the frequency for the propagating modes. In fact, all modes are more or less attenuated, so it is even more important to compute the dispersion curves, which provide also the modal attenuation as function of frequency. Another important aspect is the sensitivity of the dispersion curves on each of the elastic constant of the composite, which are orthotropic in most cases. All these aspects are investigated in the present work, based on our specially developed finite element numerical model implemented in Comsol, which has several advantages over existing methods. The dispersion curves and modal displacements are computed for an example of composite plate. Comparison with literature data validates the accuracy of our results.

Comparison between hybrid laser-MIG welding and MIG welding for the invar36 alloy

NASA Astrophysics Data System (ADS)

Zhan, Xiaohong; Li, Yubo; Ou, Wenmin; Yu, Fengyi; Chen, Jie; Wei, Yanhong

2016-11-01

The invar36 alloy is suitable to produce mold of composite materials structure because it has similar thermal expansion coefficient with composite materials. In the present paper, the MIG welding and laser-MIG hybrid welding methods are compared to get the more appropriate method to overcome the poor weldability of invar36 alloy. According to the analysis of the experimental and simulated results, it has been proved that the Gauss and cone combined heat source model can characterize the laser-MIG hybrid welding heat source well. The total welding time of MIG welding is 8 times that of hybrid laser-MIG welding. The welding material consumption of MIG welding is about 4 times that of hybrid laser-MIG welding. The stress and deformation simulation indicate that the peak value of deformation during MIG welding is 3 times larger than that of hybrid laser-MIG welding.

The effect of mechanical stress on electric resistance of nanographite-epoxy composites

NASA Astrophysics Data System (ADS)

Vovchenko, L.; Lazarenko, A.; Matzui, L.; Zhuravkov, A.

2012-03-01

The in-plane electric resistance Ra of composite materials (CMs) thermoexfoliated graphite(TEG)-epoxy resin(ED) under compression along compacting C-axis has been investigated by four-probe method. TEG content was 5-75 wt%. It was shown that specimens prepared by cold pressing are denser and reveal lower values of electric resistivity in comparison with specimens prepared by pouring. It was found that compression of the specimens leads to plastic deformation of specimens (εpl) and essential irreversible decrease of electric resistance during the first cycle of loading (up to 50 MPa), especially for the poured specimens with low density. Within the proposed model the contact resistance Rk between graphite particles in CM has been evaluated and it was shown that it increased with the decrease in TEG content in CM and depends on compacting method of CMs and the dispersity of graphite filler.

Microwave-Assisted Hydro-Distillation of Essential Oil from Rosemary: Comparison with Traditional Distillation.

PubMed

Moradi, Sara; Fazlali, Alireza; Hamedi, Hamid

2018-01-01

Hydro-distillation (HD) method is a traditional technique which is used in most industrial companies. Microwave-assisted Hydro-distillation (MAHD) is an advanced HD technique utilizing a microwave oven in the extraction process. In this research, MAHD of essential oils from the aerial parts (leaves) of rosemary ( Rosmarinus officinalis L. ) was studied and the results were compared with those of the conventional HD in terms of extraction time, extraction efficiency, chemical composition, quality of the essential oils and cost of the operation. Microwave hydro-distillation was superior in terms of saving energy and extraction time (30 min , compared to 90 min in HD). Chromatography was used for quantity analysis of the essential oils composition. Quality of essential oil improved in MAHD method due to an increase of 17% in oxygenated compounds. Consequently, microwave hydro-distillation can be used as a substitute of traditional hydro-distillation.

Composition, Context, and Endogeneity in School and Teacher Comparisons

ERIC Educational Resources Information Center

Castellano, Katherine E.; Rabe-Hesketh, Sophia; Skrondal, Anders

2014-01-01

Investigations of the effects of schools (or teachers) on student achievement focus on either (1) individual school effects, such as value-added analyses, or (2) school-type effects, such as comparisons of charter and public schools. Controlling for school composition by including student covariates is critical for valid estimation of either kind…

Beef patty composition: effects of fat content and cooking method.

PubMed

Berry, B W; Leddy, K

1984-06-01

Patties from ground round, ground chuck , and regular ground beef containing 14%, 19%, and 24% fat, respectively, were cooked by six different methods and analyzed for compositional differences. Cooking methods were electric broiling , charbroiling , roasting, convection heating, frying, and microwave heating. Percent yield, fat, and moisture of cooked patties were significantly affected (p less than .05) by the interaction of fat level and cooking method. Except for patties cooked by broiling or convection heating, patty yields decreased with increasing fat levels. Leaner formulations of ground beef increased in fat percentage with cooking, while patties processed to contain more fat initially decreased in fat percentage following cooking. Microwave cooking always produced patties containing the least fat and caloric content in comparison with other methods. Increasing levels of fat in the raw patty formulation did not appear to affect substantially the total caloric value of the patties following cooking. Cooked patties processed to have 14% fat contained slightly more water and less fat than patties having 24% fat. At current retail prices, cooked patties made to have 14% fat cost +0.20 more per patty than patties produced to contain 24% fat, regardless of the method of cooking.

Effects of optical dopants and laser wavelength on atom probe tomography analyses of borosilicate glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Xiaonan; Schreiber, Daniel K.; Neeway, James J.

Atom probe tomography (APT) is a novel analytical microscopy method that provides three dimensional elemental mapping with sub-nanometer spatial resolution and has only recently been applied to insulating glass and ceramic samples. In this paper, we have studied the influence of the optical absorption in glass samples on APT characterization by introducing different transition metal optical dopants to a model borosilicate nuclear waste glass (international simple glass). A systematic comparison is presented of the glass optical properties and the resulting APT data quality in terms of compositional accuracy and the mass spectra quality for two APT systems: one with amore » green laser (532 nm, LEAP 3000X HR) and one with a UV laser (355 nm, LEAP 4000X HR). These data were also compared to the study of a more complex borosilicate glass (SON68). The results show that the analysis data quality such as compositional accuracy and total ions collected, was clearly linked to optical absorption when using a green laser, while for the UV laser optical doping aided in improving data yield but did not have a significant effect on compositional accuracy. Comparisons of data between the LEAP systems suggest that the smaller laser spot size of the LEAP 4000X HR played a more critical role for optimum performance than the optical dopants themselves. The smaller spot size resulted in more accurate composition measurements due to a reduced background level independent of the material’s optical properties.« less

ISO 15859 Propellant and Fluid Specifications: A Review and Comparison with Military and NASA Specifications

NASA Technical Reports Server (NTRS)

Greene, Ben; McClure, Mark B.; Baker, David L.

2006-01-01

This work presents an overview of the International Organization for Standardization (ISO) 15859 International Standard for Space Systems Fluid Characteristics, Sampling and Test Methods Parts 1 through 13 issued in June 2004. These standards establish requirements for fluid characteristics, sampling, and test methods for 13 fluids of concern to the propellant community and propellant characterization laboratories: oxygen, hydrogen, nitrogen, helium, nitrogen tetroxide, monomethylhydrazine, hydrazine, kerosene, argon, water, ammonia, carbon dioxide, and breathing air. A comparison of the fluid characteristics, sampling, and test methods required by the ISO standards to the current military and NASA specifications, which are in use at NASA facilities and elsewhere, is presented. Many ISO standards composition limits and other content agree with those found in the applicable parts of NASA SE-S-0073, NASA SSP 30573, military performance standards and details, and Compressed Gas Association (CGA) commodity specifications. The status of a current project managed at NASA Johnson Space Center White Sands Test Facility (WSTF) to rewrite these documents is discussed.

A comparison of essential oils obtained from lavandin via different extraction processes: Ultrasound, microwave, turbohydrodistillation, steam and hydrodistillation.

PubMed

Périno-Issartier, Sandrine; Ginies, Christian; Cravotto, Giancarlo; Chemat, Farid

2013-08-30

A total of eight extraction techniques ranging from conventional methods (hydrodistillation (HD), steam distillation (SD), turbohydrodistillation (THD)), through innovative techniques (ultrasound assisted extraction (US-SD) and finishing with microwave assisted extraction techniques such as In situ microwave-generated hydrodistillation (ISMH), microwave steam distillation (MSD), microwave hydrodiffusion and gravity (MHG), and microwave steam diffusion (MSDf)) were used to extract essential oil from lavandin flowers and their results were compared. Extraction time, yield, essential oil composition and sensorial analysis were considered as the principal terms of comparison. The essential oils extracted using the more innovative processes were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained from the conventional techniques. The method which gave the best results was the microwave hydrodiffusion and gravity (MHG) method which gave reduced extraction time (30min against 220min for SD) and gave no differences in essential oil yield and sensorial perception. Copyright © 2013 Elsevier B.V. All rights reserved.

Numerical studies of the thermal design sensitivity calculation for a reaction-diffusion system with discontinuous derivatives

NASA Technical Reports Server (NTRS)

Hou, Jean W.; Sheen, Jeen S.

1987-01-01

The aim of this study is to find a reliable numerical algorithm to calculate thermal design sensitivities of a transient problem with discontinuous derivatives. The thermal system of interest is a transient heat conduction problem related to the curing process of a composite laminate. A logical function which can smoothly approximate the discontinuity is introduced to modify the system equation. Two commonly used methods, the adjoint variable method and the direct differentiation method, are then applied to find the design derivatives of the modified system. The comparisons of numerical results obtained by these two methods demonstrate that the direct differentiation method is a better choice to be used in calculating thermal design sensitivity.

Prediction and analysis of protein solubility using a novel scoring card method with dipeptide composition

PubMed Central

2012-01-01

Background Existing methods for predicting protein solubility on overexpression in Escherichia coli advance performance by using ensemble classifiers such as two-stage support vector machine (SVM) based classifiers and a number of feature types such as physicochemical properties, amino acid and dipeptide composition, accompanied with feature selection. It is desirable to develop a simple and easily interpretable method for predicting protein solubility, compared to existing complex SVM-based methods. Results This study proposes a novel scoring card method (SCM) by using dipeptide composition only to estimate solubility scores of sequences for predicting protein solubility. SCM calculates the propensities of 400 individual dipeptides to be soluble using statistic discrimination between soluble and insoluble proteins of a training data set. Consequently, the propensity scores of all dipeptides are further optimized using an intelligent genetic algorithm. The solubility score of a sequence is determined by the weighted sum of all propensity scores and dipeptide composition. To evaluate SCM by performance comparisons, four data sets with different sizes and variation degrees of experimental conditions were used. The results show that the simple method SCM with interpretable propensities of dipeptides has promising performance, compared with existing SVM-based ensemble methods with a number of feature types. Furthermore, the propensities of dipeptides and solubility scores of sequences can provide insights to protein solubility. For example, the analysis of dipeptide scores shows high propensity of α-helix structure and thermophilic proteins to be soluble. Conclusions The propensities of individual dipeptides to be soluble are varied for proteins under altered experimental conditions. For accurately predicting protein solubility using SCM, it is better to customize the score card of dipeptide propensities by using a training data set under the same specified experimental conditions. The proposed method SCM with solubility scores and dipeptide propensities can be easily applied to the protein function prediction problems that dipeptide composition features play an important role. Availability The used datasets, source codes of SCM, and supplementary files are available at http://iclab.life.nctu.edu.tw/SCM/. PMID:23282103

A scoring metric for multivariate data for reproducibility analysis using chemometric methods

PubMed Central

Sheen, David A.; de Carvalho Rocha, Werickson Fortunato; Lippa, Katrice A.; Bearden, Daniel W.

2017-01-01

Process quality control and reproducibility in emerging measurement fields such as metabolomics is normally assured by interlaboratory comparison testing. As a part of this testing process, spectral features from a spectroscopic method such as nuclear magnetic resonance (NMR) spectroscopy are attributed to particular analytes within a mixture, and it is the metabolite concentrations that are returned for comparison between laboratories. However, data quality may also be assessed directly by using binned spectral data before the time-consuming identification and quantification. Use of the binned spectra has some advantages, including preserving information about trace constituents and enabling identification of process difficulties. In this paper, we demonstrate the use of binned NMR spectra to conduct a detailed interlaboratory comparison and composition analysis. Spectra of synthetic and biologically-obtained metabolite mixtures, taken from a previous interlaboratory study, are compared with cluster analysis using a variety of distance and entropy metrics. The individual measurements are then evaluated based on where they fall within their clusters, and a laboratory-level scoring metric is developed, which provides an assessment of each laboratory’s individual performance. PMID:28694553

Chemometric Methods to Quantify 1D and 2D NMR Spectral Differences Among Similar Protein Therapeutics.

PubMed

Chen, Kang; Park, Junyong; Li, Feng; Patil, Sharadrao M; Keire, David A

2018-04-01

NMR spectroscopy is an emerging analytical tool for measuring complex drug product qualities, e.g., protein higher order structure (HOS) or heparin chemical composition. Most drug NMR spectra have been visually analyzed; however, NMR spectra are inherently quantitative and multivariate and thus suitable for chemometric analysis. Therefore, quantitative measurements derived from chemometric comparisons between spectra could be a key step in establishing acceptance criteria for a new generic drug or a new batch after manufacture change. To measure the capability of chemometric methods to differentiate comparator NMR spectra, we calculated inter-spectra difference metrics on 1D/2D spectra of two insulin drugs, Humulin R® and Novolin R®, from different manufacturers. Both insulin drugs have an identical drug substance but differ in formulation. Chemometric methods (i.e., principal component analysis (PCA), 3-way Tucker3 or graph invariant (GI)) were performed to calculate Mahalanobis distance (D M ) between the two brands (inter-brand) and distance ratio (D R ) among the different lots (intra-brand). The PCA on 1D inter-brand spectral comparison yielded a D M value of 213. In comparing 2D spectra, the Tucker3 analysis yielded the highest differentiability value (D M  = 305) in the comparisons made followed by PCA (D M  = 255) then the GI method (D M  = 40). In conclusion, drug quality comparisons among different lots might benefit from PCA on 1D spectra for rapidly comparing many samples, while higher resolution but more time-consuming 2D-NMR-data-based comparisons using Tucker3 analysis or PCA provide a greater level of assurance for drug structural similarity evaluation between drug brands.

Body composition and size in sprint athletes.

PubMed

Barbieri, Davide; Zaccagni, Luciana; Babić, Vesna; Rakovac, Marija; Mišigoj-Duraković, Marjeta; Gualdi-Russo, Emanuela

2017-09-01

The aims of the present study were to assess competitive sprinters' body size and composition and to determine their impact on performance. Ninety-eight competitive male sprinters (100 m) participated in this cross-sectional study. A series of measurements was directly taken and data on muscular strength and power tests were self-reported. Body composition was assessed by skinfold method and somatotype was calculated by the Heath-Carter anthropometric method. Sprinters were classified into three groups depending on their personal best time and comparisons were performed between the athletes in the top and in the bottom tertiles. Relationships between anthropometric traits and performance were assessed by Pearson's correlation coefficients. Top sprinters had significantly greater body mass index, relaxed and contracted upper arm girths, thigh and calf girths, fat free mass and fat free mass index, and lower ectomorphy than the lowest tertile. Strength and power were significantly higher. Personal best time was significantly correlated with several anthropometric traits and indices of lean body mass. Body size, composition and somatotype differ between performance levels in speed running. Being less ectomorphic, with a greater fat free mass and strength, can explain significant differences in sprinting performances. The results presented in this study provide a point of reference about sprinter characteristics, which can help coaches and sport scientists to improve sprinter performance.

A New Trend-Following Indicator: Using SSA to Design Trading Rules

NASA Astrophysics Data System (ADS)

Leles, Michel Carlo Rodrigues; Mozelli, Leonardo Amaral; Guimarães, Homero Nogueira

Singular Spectrum Analysis (SSA) is a non-parametric approach that can be used to decompose a time-series as trends, oscillations and noise. Trend-following strategies rely on the principle that financial markets move in trends for an extended period of time. Moving Averages (MAs) are the standard indicator to design such strategies. In this study, SSA is used as an alternative method to enhance trend resolution in comparison with the traditional MA. New trading rules using SSA as indicator are proposed. This paper shows that for the Down Jones Industrial Average (DJIA) and Shangai Securities Composite Index (SSCI) time-series the SSA trading rules provided, in general, better results in comparison to MA trading rules.

Comparison of neck skin excision and whole carcass rinse sampling methods for determining Salmonella prevalence and E. coli counts on broiler carcasses before and after immersion chilling

USDA-ARS?s Scientific Manuscript database

A regulatory agency (FSIS) in the U.S. rinses whole broiler carcasses with 400 ml of 1% buffered peptone water (BPW) for Salmonella detection, while the European Union (EU) samples a 25g composited neck skin from three carcasses. The purpose of the study was to evaluate the FSIS and EU procedures fo...

Analysis of the fly ash from the processing of wood chips in a pilot-scale downdraft gasifier: Comparison of inorganic constituents determined by PIXE and ICP-AES

Treesearch

Thomas L Eberhardt; Hui Pan

2013-01-01

Gasification of biomass ultimately generates at least one solid byproduct in which the inorganic constituents of the biomass are concentrated. Given the potential for utilization, or issues with disposal, facile methods are needed for determining the compositions of the fly ashes from recently-available gasifier-based bioenergy systems. Proton induced x-ray emission...

Shear properties of pultruded fiber reinforced polymer composite materials

NASA Astrophysics Data System (ADS)

Seo, J. H.; Kim, S. H.; Ok, D. M.; An, D. J.; Yoon, S. J.

2018-06-01

This paper focuses on the mechanical properties of PFRP composite materials. Especially, relationship between shear property and the other mechanical properties of PFRP composite materials is investigated through comparison between experimental and theoretical results. The shear property of PFRP composite specimen is calculated from the theoretical equations which were suggested in previous studies. In addition, comparison between the shear property determined by the tensile test and the shear property calculated from theoretical equations is conducted and discussed. It was found that the theoretically predicted shear modulus of elasticity considering contiguity is close to the shear modulus of elasticity obtained by the 45° off-axis tensile test.

Experimental Study on Welded Headed Studs Used In Steel Plate-Concrete Composite Structures Compared with Contactless Method of Measuring Displacement

NASA Astrophysics Data System (ADS)

Kisała, Dawid; Tekieli, Marcin

2017-10-01

Steel plate-concrete composite structures are a new innovative design concept in which a thin steel plate is attached to the reinforced concrete beam by means of welded headed studs. The comparison between experimental studies and theoretical analysis of this type of structures shows that their behaviour is dependent on the load-slip relationship of the shear connectors used to ensure sufficient bond between the concrete and steel parts of the structure. The aim of this paper is to describe an experimental study on headed studs used in steel plate-concrete composite structures. Push-out tests were carried out to investigate the behaviour of shear connectors. The test specimens were prepared according to standard push-out tests, however, instead of I-beam, a steel plate 16 mm thick was used to better reflect the conditions in the real structure. The test specimens were produced in two batches using concrete with significantly different compressive strength. The experimental study was carried out on twelve specimens. Besides the traditional measurements based on LVDT sensors, optical measurements based on the digital image correlation method (DIC) and pattern tracking methods were used. DIC is a full-field contactless optical method for measuring displacements in experimental testing, based on the correlation of the digital images taken during test execution. With respect to conventional methods, optical measurements offer a wider scope of results and can give more information about the material or construction behaviour during the test. The ultimate load capacity and load-slip curves obtained from the experiments were compared with the values calculated based on Eurocodes, American and Chinese design specifications. It was observed that the use of the relationships developed for the traditional steel-concrete composite structures is justified in the case of ultimate load capacity of shear connectors in steel plate-concrete composite structures.

Comparison of Peak-area Ratios and Percentage Peak Area Derived from HPLC-evaporative Light Scattering and Refractive Index Detectors for Palm Oil and its Fractions.

PubMed

Ping, Bonnie Tay Yen; Aziz, Haliza Abdul; Idris, Zainab

2018-01-01

High-Performance Liquid Chromatography (HPLC) methods via evaporative light scattering (ELS) and refractive index (RI) detectors are used by the local palm oil industry to monitor the TAG profiles of palm oil and its fractions. The quantitation method used is based on area normalization of the TAG components and expressed as percentage area. Although not frequently used, peak-area ratios based on TAG profiles are a possible qualitative method for characterizing the TAG of palm oil and its fractions. This paper aims to compare these two detectors in terms of peak-area ratio, percentage peak area composition, and TAG elution profiles. The triacylglycerol (TAG) composition for palm oil and its fractions were analysed under similar HPLC conditions i.e. mobile phase and column. However, different sample concentrations were used for the detectors while remaining within the linearity limits of the detectors. These concentrations also gave a good baseline resolved separation for all the TAGs components. The results of the ELSD method's percentage area composition for the TAGs of palm oil and its fractions differed from those of RID. This indicates an unequal response of TAGs for palm oil and its fractions using the ELSD, also affecting the peak area ratios. They were found not to be equivalent to those obtained using the HPLC-RID. The ELSD method showed a better baseline separation for the TAGs components, with a more stable baseline as compared with the corresponding HPLC-RID. In conclusion, the percentage area compositions and peak-area ratios for palm oil and its fractions as derived from HPLC-ELSD and RID were not equivalent due to different responses of TAG components to the ELSD detector. The HPLC-RID has a better accuracy for percentage area composition and peak-area ratio because the TAG components response equally to the detector.

Antibacterial and antibiofouling clay nanotube–silicone composite

PubMed Central

Boyer, CJ; Ambrose, J; Das, S; Humayun, A; Chappidi, D; Giorno, R; Mills, DK

2018-01-01

Introduction Invasive medical devices are used in treating millions of patients each day. Bacterial adherence to their surface is an early step in biofilm formation that may lead to infection, health complications, longer hospital stays, and death. Prevention of bacterial adherence and biofilm development continues to be a major healthcare challenge. Accordingly, there is a pressing need to improve the anti-microbial properties of medical devices. Materials and Methods Polydimethylsiloxane (PDMS) was doped with halloysite nanotubes (HNTs), and the PDMS-HNT composite surfaces were coated with PDMS-b-polyethylene oxide (PEO) and antibacterials. The composite material properties were examined using SEM, energy dispersive spectroscopy, water contact angle measurements, tensile testing, UV-Vis spectroscopy, and thermal gravimetric analysis. The antibacterial potential of the PDMS-HNT composites was compared to commercial urinary catheters using cultures of E. coli and S. aureus. Fibrinogen adsorption studies were also performed on the PDMS-HNT-PEO composites. Results HNT addition increased drug load during solvent swelling without reducing material strength. The hydrophilic properties provided by PEO were maintained after HNT addition, and the composites displayed protein-repelling properties. Additionally, composites showed superiority over commercial catheters at inhibiting bacterial growth. Conclusion PDMS-HNT composites showed superiority regarding their efficacy at inhibiting bacterial growth, in comparison to commercial antibacterial catheters. Our data suggest that PDMS-HNT composites have potential as a coating material for anti-bacterial invasive devices and in the prevention of institutional-acquired infections. PMID:29713206

Thermal Scanning of Dental Pulp Chamber by Thermocouple System and Infrared Camera during Photo Curing of Resin Composites

PubMed Central

Hamze, Faeze; Ganjalikhan Nasab, Seyed Abdolreza; Eskandarizadeh, Ali; Shahravan, Arash; Akhavan Fard, Fatemeh; Sinaee, Neda

2018-01-01

Introduction: Due to thermal hazard during composite restorations, this study was designed to scan the pulp temperature by thermocouple and infrared camera during photo polymerizing different composites. Methods and Materials: A mesio-occlso-distal (MOD) cavity was prepared in an extracted tooth and the K-type thermocouple was fixed in its pulp chamber. Subsequently, 1 mm increment of each composites were inserted (four composite types were incorporated) and photo polymerized employing either LED or QTH systems for 60 sec while the temperature was recorded with 10 sec intervals. Ultimately, the same tooth was hemisected bucco-lingually and the amalgam was removed. The same composite curing procedure was repeated while the thermogram was recorded using an infrared camera. Thereafter, the data was analyzed by repeated measured ANOVA followed by Tukey’s HSD Post Hoc test for multiple comparisons (α=0.05). Results: The pulp temperature was significantly increased (repeated measures) during photo polymerization (P=0.000) while there was no significant difference among the results recorded by thermocouple comparing to infrared camera (P>0.05). Moreover, different composite materials and LCUs lead to similar outcomes (P>0.05). Conclusion: Although various composites have significant different chemical compositions, they lead to similar pulp thermal changes. Moreover, both the infrared camera and the thermocouple would record parallel results of dental pulp temperature. PMID:29707014

Lamb wave propagation in a restricted geometry composite pi-joint specimen

NASA Astrophysics Data System (ADS)

Blackshire, James L.; Soni, Som

2012-05-01

The propagation of elastic waves in a material can involve a number of complex physical phenomena, resulting in both subtle and dramatic effects on detected signal content. In recent years, the use of advanced methods for characterizing and imaging elastic wave propagation and scattering processes has increased, where for example the use of scanning laser vibrometry and advanced computational models have been used very effectively to identify propagating modes, scattering phenomena, and damage feature interactions. In the present effort, the propagation of Lamb waves within a narrow, constrained geometry composite pi-joint structure are studied using 3D finite element models and scanning laser vibrometry measurements, where the effects of varying sample thickness, complex joint curvatures, and restricted structure geometries are highlighted, and a direct comparison of computational and experimental results are provided for simulated and realistic geometry composite pi-joint samples.

Integrated NDE and FEM characterization of composite rotors

NASA Astrophysics Data System (ADS)

Abdul-Aziz, Ali; Baaklini, George Y.; Trudell, Jeffrey J.

2001-08-01

A structural assessment by integrating finite-element methods (FEM) and a nondestructive evaluation (NDE) of two flywheel rotor assemblies is presented. Composite rotor A is pancake like with a solid hub design, and composite rotor B is cylindrical with a hollow hub design. Detailed analyses under combined centrifugal and interference-fit loading are performed. Two- and three-dimensional stress analyses and two-dimensional fracture mechanics analyses are conducted. A comparison of the structural analysis results obtained with those extracted via NDE findings is reported. Contact effects due to press-fit conditions are evaluated. Stress results generated from the finite-element analyses were corroborated with the analytical solution. Cracks due to rotational loading up to 48 000 rpm for rotor A and 34 000 rpm for rotor B were successfully imaged with NDE and predicted with FEM and fracture mechanics analyses. A procedure that extends current structural analysis to a life prediction tool is also defined.

An Integrated NDE and FEM Characterization of Composite Rotors

NASA Technical Reports Server (NTRS)

Abdul-Aziz, Ali; Baaklini, George Y.; Trudell, Jeffrey J.

2000-01-01

A structural assessment by integrating finite-element methods (FEM) and a nondestructive evaluation (NDE) of two flywheel rotor assemblies is presented. Composite rotor A is pancake like with a solid hub design, and composite rotor B is cylindrical with a hollow hub design. Detailed analyses under combined centrifugal and interference-fit loading are performed. Two- and three-dimensional stress analyses and two-dimensional fracture mechanics analyses are conducted. A comparison of the structural analysis results obtained with those extracted via NDE findings is reported. Contact effects due to press-fit conditions are evaluated. Stress results generated from the finite-element analyses were corroborated with the analytical solution. Cracks due to rotational loading up to 49 000 rpm for rotor A and 34 000 rpm for rotor B were successfully imaged with NDE and predicted with FEM and fracture mechanics analyses. A procedure that extends current structural analysis to a life prediction tool is also defined.

Structural Analysis of Composite Flywheels: an Integrated NDE and FEM Approach

NASA Technical Reports Server (NTRS)

Abdul-Aziz, Ali; Baaklini, George; Trudell, Jeffrey

2001-01-01

A structural assessment by integrating finite-element methods (FEM) and a nondestructive evaluation (NDE) of two flywheel rotor assemblies is presented. Composite rotor A is pancake-like with a solid hub design, and composite rotor B is cylindrical with a hollow hub design. Detailed analyses under combined centrifugal and interference-fit loading are performed. Two- and three-dimensional stress analyses and two-dimensional fracture mechanics analyses are conducted. A comparison of the structural analysis results obtained with those extracted via NDE findings is reported. Contact effects due to press-fit conditions are evaluated. Stress results generated from the finite-element analyses were corroborated with the analytical solution. Cracks due to rotational loading up to 48,000 rpm for rotor A and 34,000 rpm for rotor B were successfully imaged with NDE and predicted with FEM and fracture mechanics analyses. A procedure that extends current structural analysis to a life prediction tool is also defined.

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

NASA Astrophysics Data System (ADS)

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli; Radney, James G.; Kolesar, Katheryn R.; Zhang, Qi; Setyan, Ari; O'Neill, Norman T.; Cappa, Christopher D.

2018-04-01

Multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare well with other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM1 and PM10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

DOE PAGES

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli; ...

2018-04-23

Here, multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare wellmore » with other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM 1 and PM 10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.« less

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli

Here, multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare wellmore » with other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM 1 and PM 10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.« less

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atkinson, Dean B.; Pekour, Mikhail; Chand, Duli

Multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare well withmore » other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM 1 and PM 10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.« less

Methodology development for quantitative optimization of security enhancement in medical information systems -Case study in a PACS and a multi-institutional radiotherapy database-.

PubMed

Haneda, Kiyofumi; Umeda, Tokuo; Koyama, Tadashi; Harauchi, Hajime; Inamura, Kiyonari

2002-01-01

The target of our study is to establish the methodology for analyzing level of security requirements, for searching suitable security measures and for optimizing security distribution to every portion of medical practice. Quantitative expression must be introduced to our study as possible for the purpose of easy follow up of security procedures and easy evaluation of security outcomes or results. Results of system analysis by fault tree analysis (FTA) clarified that subdivided system elements in detail contribute to much more accurate analysis. Such subdivided composition factors very much depended on behavior of staff, interactive terminal devices, kinds of service, and routes of network. As conclusion, we found the methods to analyze levels of security requirements for each medical information systems employing FTA, basic events for each composition factor and combination of basic events. Methods for searching suitable security measures were found. Namely risk factors for each basic event, number of elements for each composition factor and candidates of security measure elements were found. Method to optimize the security measures for each medical information system was proposed. Namely optimum distribution of risk factors in terms of basic events were figured out, and comparison of them between each medical information systems became possible.

Testing the Predictive Capability of the High-Fidelity Generalized Method of Cells Using an Efficient Reformulation

NASA Technical Reports Server (NTRS)

Arnold, Steven M. (Technical Monitor); Bansal, Yogesh; Pindera, Marek-Jerzy

2004-01-01

The High-Fidelity Generalized Method of Cells is a new micromechanics model for unidirectionally reinforced periodic multiphase materials that was developed to overcome the original model's shortcomings. The high-fidelity version predicts the local stress and strain fields with dramatically greater accuracy relative to the original model through the use of a better displacement field representation. Herein, we test the high-fidelity model's predictive capability in estimating the elastic moduli of periodic composites characterized by repeating unit cells obtained by rotation of an infinite square fiber array through an angle about the fiber axis. Such repeating unit cells may contain a few or many fibers, depending on the rotation angle. In order to analyze such multi-inclusion repeating unit cells efficiently, the high-fidelity micromechanics model's framework is reformulated using the local/global stiffness matrix approach. The excellent agreement with the corresponding results obtained from the standard transformation equations confirms the new model's predictive capability for periodic composites characterized by multi-inclusion repeating unit cells lacking planes of material symmetry. Comparison of the effective moduli and local stress fields with the corresponding results obtained from the original Generalized Method of Cells dramatically highlights the original model's shortcomings for certain classes of unidirectional composites.

[Two compartment model of body composition and abdominal fat area in postmenopausal women - pilot study].

PubMed

Milewska, Magdalena; Mioduszewska, Milena; Pańczyk, Mariusz; Kucharska, Alicja; Sińska, Beata; Dąbrowska-Bender, Marta; Michota-Katulska, Ewa; Zegan, Magdalena; Szabla, Anna

2016-01-01

Both menopausal period and aging have influence on body composition, increase of total body fat and visceral fat in particular. We should be aware that changes in body composition, mainly fat translocation to abdominal region, can occur without significant changes in body weight. Therefore quantitative abdominal fat assessment should be our aim. Body composition analysis based on two compartment model and abdominal fat area assessment in cross section. Subjects in postmenopausal period (41 women) were recruited for this study and divided into 2 groups: group 1 - women aged 45-56 years and group 2 - women aged 57-79 years. Body composition analysis and abdominal fat area assessment were conducted by using bioelectrical impedance method with BioScan 920 (Maltron int.) accordingly with standardized procedure. Women in early postmenopausal stage (Group 1) had statistically significant lower total body fat percentage in comparison with women in late postmenopausal period (Group 2) (41.09 ± 7.72% vs. 50.7 ± 9.88%, p=0.0021). Also women in group 1 were characterized by significant lower visceral fat area (VAT) as well as subcutaneous fat area (SAT) in comparison with group 2 (respectively VAT 119.25 ± 30.09 cm2 vs. 199.36 ± 87.38 cm2, p=0.0011; SAT 175.19 ±57.67 cm2 vs. 223.4±74.29 cm2, p=0.0336). According to VAT criteria (>120 cm2), 44% of women in group 1 and 80% in group 2 had excess of visceral fat. Both total body fat and intra-abdominal fat increased with age, independently of weight changes.

An Analytical Investigation of Three General Methods of Calculating Chemical-Equilibrium Compositions

NASA Technical Reports Server (NTRS)

Zeleznik, Frank J.; Gordon, Sanford

1960-01-01

The Brinkley, Huff, and White methods for chemical-equilibrium calculations were modified and extended in order to permit an analytical comparison. The extended forms of these methods permit condensed species as reaction products, include temperature as a variable in the iteration, and permit arbitrary estimates for the variables. It is analytically shown that the three extended methods can be placed in a form that is independent of components. In this form the Brinkley iteration is identical computationally to the White method, while the modified Huff method differs only'slightly from these two. The convergence rates of the modified Brinkley and White methods are identical; and, further, all three methods are guaranteed to converge and will ultimately converge quadratically. It is concluded that no one of the three methods offers any significant computational advantages over the other two.

Health Monitoring of Composite Material Structures using a Vibrometry Technique

NASA Technical Reports Server (NTRS)

Schulz, Mark J.

1997-01-01

Large composite material structures such as aircraft and Reusable Launch Vehicles (RLVS) operate in severe environments comprised of vehicle dynamic loads, aerodynamic loads, engine vibration, foreign object impact, lightning strikes, corrosion, and moisture absorption. These structures are susceptible to damage such as delamination, fiber breaking/pullout, matrix cracking, and hygrothermal strain. To ensure human safety and load-bearing integrity, these structures must be inspected to detect and locate often invisible damage and faults before becoming catastrophic. Moreover, nearly all future structures will need some type of in-service inspection technique to increase their useful life and reduce maintenance and overall costs. Possible techniques for monitoring the health and indicating damage on composite structures include: c-scan, thermography, acoustic emissions using piezoceramic actuators or fiber-optic wires with gratings, laser ultrasound, shearography, holography, x-ray, and others. These techniques have limitations in detecting damage that is beneath the surface of the structure, far away from a sensor location, or during operation of the vehicle. The objective of this project is to develop a more global method for damage detection that is based on structural dynamics principles, and can inspect for damage when the structure is subjected to vibratory loads to expose faults that may not be evident by static inspection. A Transmittance Function Monitoring (TFM) method is being developed in this project for ground-based inspection and operational health monitoring of large composite structures as a RLV. A comparison of the features of existing health monitoring approaches and the proposed TFM method is given.

Predicting the mineral composition of dust aerosols – Part 1: Representing key processes

DOE PAGES

Perlwitz, J. P.; Perez Garcia-Pando, C.; Miller, R. L.

2015-10-21

Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accountsmore » for measurements showing significant differences between the mineral fractions of the wet-sieved soil and the emitted aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent at these diameters in a soil whose aggregates are dispersed by wet sieving. We calculate the emitted mass of each mineral with respect to size by accounting for the disintegration of soil aggregates during wet sieving. These aggregates are emitted during mobilization and fragmentation of the original undispersed soil that is subject to wind erosion. The emitted aggregates are carried far downwind from their parent soil. The soil mineral fractions used to calculate the aggregates also include larger particles that are suspended only in the vicinity of the source. We calculate the emitted size distribution of these particles using a normalized distribution derived from aerosol measurements. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. Finally, a limited comparison to measurements from North Africa shows that the model extensions result in better agreement, consistent with a more extensive comparison to global observations as well as measurements of elemental composition downwind of the Sahara, as described in companion articles.« less

A porous Cu/LDPE composite for copper-containing intrauterine contraceptive devices.

PubMed

Zhang, Weiwei; Xia, Xianping; Qi, Cheng; Xie, Changsheng; Cai, Shuizhou

2012-02-01

To improve the rates of both cupric ion release and the utilization of copper in non-porous copper/low-density polyethylene (Cu/LDPE) composite, a porous Cu/LDPE composite is proposed and developed in the present work. Here 2,5-di-tert-butylhydroquinone was chosen as the porogen, ethyl acetate was chosen as the solvent for extraction, and the porous Cu/LDPE composite was obtained by using injection molding and the particulate leaching method. After any residual ethyl acetate remaining inside the porous Cu/LDPE composite had been removed by vacuum drying, the composite was characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry and absorption measurement. For comparison, a non-porous Cu/LDPE composite was also characterized in the same way. The results show that the porous structure was successfully introduced into the polymeric base of the non-porous Cu/LDPE composite, and the porous Cu/LDPE composite is a simple hybrid of copper particles and porous LDPE. The results also show that the introduction of a porous structure can improve the cupric ion release rate of the non-porous Cu/LDPE composite with a certain content of copper particles, indicating that the utilization rate of copper can be improved either the introduction of a porous structure, and that the porous Cu/LDPE composite is another promising material for copper-containing intrauterine devices. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Comparison of diet consumption, body composition and lipoprotein lipid values of Kuwaiti fencing players with international norms

PubMed Central

2011-01-01

Background No published data is currently available that describes the dietary patterns or physiological profiles of athletes participating on the Kuwaiti national fencing team and its potential impact on health and physical performance. The purpose of this investigation was to: 1) collect baseline data on nutrient intake 2) collect, analyze and report baseline for body composition, plasma lipid and lipoprotein concentrations during the competitive season, 3) compare the results with the international norms, 4) and provide necessary health and nutritional information in order to enhance the athletes' performance and skills. Methods Fifteen national-class fencers 21.5 ± 2.6 years of age participated in this study. Food intake was measured using a 3-day food record. Body composition was estimated using both the BOD POD and Body Mass Index (BMI). Total blood lipid profiles and maximum oxygen consumption was measured for each of the subjects during the competitive season. Results The results of the present study showed significant differences in dietary consumption in comparison with the recommended dietary allowances (RDA). The blood lipids profile and body composition (BMI and % body fat) were in normal range in comparison with international norms However, the average VO2 max value was less than the value of the other fencers. Conclusion Due to the results of the research study, a dietary regimen can be designed that would better enhance athletic performance and minimize any health risks associated with nutrition. Percent body fat and BMI will also be categorized for all players. In addition, the plasma blood tests will help to determine if any of the players have an excessive level of lipids or any blood abnormalities. The outcomes of present study will have a direct impact on the players health and therefore their skills and athletic performance. PMID:21992447

Comprehensive Assessment of Composition and Thermochemical Variability by High Resolution GC/QToF-MS and the Advanced Distillation-Curve Method as a Basis of Comparison for Reference Fuel Development.

PubMed

Lovestead, Tara M; Burger, Jessica L; Schneider, Nico; Bruno, Thomas J

2016-12-15

Commercial and military aviation is faced with challenges that include high fuel costs, undesirable emissions, and supply chain insecurity that result from the reliance on petroleum-based feedstocks. The development of alternative gas turbine fuels from renewable resources will likely be part of addressing these issues. The United States has established a target for one billion gallons of renewable fuels to enter the supply chain by 2018. These alternative fuels will have to be very similar in properties, chemistry, and composition to existing fuels. To further this goal, the National Jet Fuel Combustion Program (a collaboration of multiple U.S. agencies under the auspices of the Federal Aviation Administration, FAA) is coordinating measurements on three reference gas turbine fuels to be used as a basis of comparison. These fuels are reference fuels with certain properties that are at the limits of experience. These fuels include a low viscosity, low flash point, high hydrogen content "best case" JP-8 (POSF 10264) fuel, a relatively high viscosity, high flash point, low hydrogen content "worst case" JP-5 (POSF 10259) fuel, and a Jet-A (POSF 10325) fuel with relatively average properties. A comprehensive speciation of these fuels is provided in this paper by use of high resolution gas chromatography/quadrupole time-of-flight - mass spectrometry (GC/QToF-MS), which affords unprecedented resolution and exact molecular formula capabilities. The volatility information as derived from the measurement of the advanced distillation curve temperatures, T k and T h , provides an approximation of the vapor liquid equilibrium and examination of the composition channels provides detailed insight into thermochemical data. A comprehensive understanding of the compositional and thermophysical data of gas turbine fuels is required not only for comparison but also for modeling of such complex mixtures, which will, in turn, aid in the development of new fuels with the goals of diversified feedstocks, decreased pollution, and increased efficiency.

Tensile Properties and Deflection Temperature of Polypropylene/Sumberejo Kenaf Fiber Composites with Fiber Content Variation

NASA Astrophysics Data System (ADS)

Ollivia, S. L.; Juwono, A. L.; Roseno, Seto

2017-05-01

The use of synthetic fibers as reinforcement in composites has disadvantage which are unsustainable and an adverse impact on the environment. An alternative reinforcement for composites is natural fiber. Polypropylene and Sumberejo kenaf fibers were used respectively as the matrix and reinforcement. The aim of this research was to obtain the optimum tensile properties and deflection temperature with the variation of kenaf fiber fractions. Polypropylene/kenaf fiber composites were fabricated by hot press method. The kenaf fiber was soaked in NaOH solution before being used as the reinforcement and polypropylene was extruded before being used as the matrix. The weight fractions were varied to produce composites and pristine polypropylene samples were also prepared for comparison. The optimum tensile strength, modulus and deflection temperature were found in the composites with the 40 wt% kenaf fiber fraction with an increase up to 80% and 170% compared to the pristine polypropylene with the values of (60.3 ± 4,3) MPa and (159.1 ± 1,8) °C respectively. The Scanning Electron Microscope observation results in the fracture surface of the composites with the 40 wt% fiber fraction showed a relatively good bonding interface between fibers and the matrix and the failure modes were fiber breakage and matrix failures.

The volumetric fraction of inorganic particles and the flexural strength of composites for posterior teeth.

PubMed

Adabo, Gelson Luis; dos Santos Cruz, Carlos Alberto; Fonseca, Renata Garcia; Vaz, Luís Geraldo

2003-07-01

To evaluate the content of inorganic particles and the flexural strength of new condensable composites for posterior teeth in comparison to hybrid conventional composites. The determination of the content of inorganic particles was performed by mass weighing of a polymerized composite before and after the elimination of the organic phase. The volumetric particle content was determined by a practical method based on Archimedes' principle, which calculates the volume of the composite and their particles by differential mass measured in the air and in water. The flexural strength of three points was evaluated according to the norm ISO 4049:1988. The results showed the following filler content: Alert, 67.26%; Z-100, 65.27%; Filtek P 60, 62.34%; Ariston pHc, 64.07%; Tetric Ceram, 57.22%; Definite, 54.42%; Solitaire, 47.76%. In the flexural strength test, the materials presented the following decreasing order of resistance: Filtek P 60 (170.02 MPa)>Z-100 (151.34 MPa)>Tetric Ceram (126.14 MPa)=Alert (124.89 MPa)>Ariston pHc (102.00 MPa)=Definite (93.63 MPa)>Solitaire (56.71 MPa). New condensable composites for posterior teeth present a concentration of inorganic particles similar to those of hybrid composites but do not necessarily present higher flexural strength.

Population Structure and Genomic Breed Composition in an Angus-Brahman Crossbred Cattle Population.

PubMed

Gobena, Mesfin; Elzo, Mauricio A; Mateescu, Raluca G

2018-01-01

Crossbreeding is a common strategy used in tropical and subtropical regions to enhance beef production, and having accurate knowledge of breed composition is essential for the success of a crossbreeding program. Although pedigree records have been traditionally used to obtain the breed composition of crossbred cattle, the accuracy of pedigree-based breed composition can be reduced by inaccurate and/or incomplete records and Mendelian sampling. Breed composition estimation from genomic data has multiple advantages including higher accuracy without being affected by missing, incomplete, or inaccurate records and the ability to be used as independent authentication of breed in breed-labeled beef products. The present study was conducted with 676 Angus-Brahman crossbred cattle with genotype and pedigree information to evaluate the feasibility and accuracy of using genomic data to determine breed composition. We used genomic data in parametric and non-parametric methods to detect population structure due to differences in breed composition while accounting for the confounding effect of close familial relationships. By applying principal component analysis (PCA) and the maximum likelihood method of ADMIXTURE to genomic data, it was possible to successfully characterize population structure resulting from heterogeneous breed ancestry, while accounting for close familial relationships. PCA results offered additional insight into the different hierarchies of genetic variation structuring. The first principal component was strongly correlated with Angus-Brahman proportions, and the second represented variation within animals that have a relatively more extended Brangus lineage-indicating the presence of a distinct pattern of genetic variation in these cattle. Although there was strong agreement between breed proportions estimated from pedigree and genetic information, there were significant discrepancies between these two methods for certain animals. This was most likely due to inaccuracies in the pedigree-based estimation of breed composition, which supported the case for using genomic information to complement and/or replace pedigree information when estimating breed composition. Comparison with a supervised analysis where purebreds are used as the training set suggest that accurate predictions can be achieved even in the absence of purebred population information.

A Comparison of Tension and Compression Creep in a Polymeric Composite and the Effects of Physical Aging on Creep Behavior

NASA Technical Reports Server (NTRS)

Gates, Thomas S.; Veazie, David R.; Brinson, L. Catherine

1996-01-01

Experimental and analytical methods were used to investigate the similarities and differences of the effects of physical aging on creep compliance of IM7/K3B composite loaded in tension and compression. Two matrix dominated loading modes, shear and transverse, were investigated for two load cases, tension and compression. The tests, run over a range of sub-glass transition temperatures, provided material constants, material master curves and aging related parameters. Comparing results from the short-term data indicated that although trends in the data with respect to aging time and aging temperature are similar, differences exist due to load direction and mode. The analytical model used for predicting long-term behavior using short-term data as input worked equally as well for the tension or compression loaded cases. Comparison of the loading modes indicated that the predictive model provided more accurate long term predictions for the shear mode as compared to the transverse mode. Parametric studies showed the usefulness of the predictive model as a tool for investigating long-term performance and compliance acceleration due to temperature.

Comparison of four extraction/methylation analytical methods to measure fatty acid composition by gas chromatography in meat.

PubMed

Juárez, M; Polvillo, O; Contò, M; Ficco, A; Ballico, S; Failla, S

2008-05-09

Four different extraction-derivatization methods commonly used for fatty acid analysis in meat (in situ or one-step method, saponification method, classic method and a combination of classic extraction and saponification derivatization) were tested. The in situ method had low recovery and variation. The saponification method showed the best balance between recovery, precision, repeatability and reproducibility. The classic method had high recovery and acceptable variation values, except for the polyunsaturated fatty acids, showing higher variation than the former methods. The combination of extraction and methylation steps had great recovery values, but the precision, repeatability and reproducibility were not acceptable. Therefore the saponification method would be more convenient for polyunsaturated fatty acid analysis, whereas the in situ method would be an alternative for fast analysis. However the classic method would be the method of choice for the determination of the different lipid classes.

A method for the geometrically nonlinear analysis of compressively loaded prismatic composite structures

NASA Technical Reports Server (NTRS)

Stoll, Frederick; Gurdal, Zafer; Starnes, James H., Jr.

1991-01-01

A method was developed for the geometrically nonlinear analysis of the static response of thin-walled stiffened composite structures loaded in uniaxial or biaxial compression. The method is applicable to arbitrary prismatic configurations composed of linked plate strips, such as stiffened panels and thin-walled columns. The longitudinal ends of the structure are assumed to be simply supported, and geometric shape imperfections can be modeled. The method can predict the nonlinear phenomena of postbuckling strength and imperfection sensitivity which are exhibited by some buckling-dominated structures. The method is computer-based and is semi-analytic in nature, making it computationally economical in comparison to finite element methods. The method uses a perturbation approach based on the use of a series of buckling mode shapes to represent displacement contributions associated with nonlinear response. Displacement contributions which are of second order in the model amplitudes are incorported in addition to the buckling mode shapes. The principle of virtual work is applied using a finite basis of buckling modes, and terms through the third order in the model amplitudes are retained. A set of cubic nonlinear algebraic equations are obtained, from which approximate equilibrium solutions are determined. Buckling mode shapes for the general class of structure are obtained using the VIPASA analysis code within the PASCO stiffened-panel design code. Thus, subject to some additional restrictions in loading and plate anisotropy, structures which can be modeled with respect to buckling behavior by VIPASA can be analyzed with respect to nonlinear response using the new method. Results obtained using the method are compared with both experimental and analytical results in the literature. The configurations investigated include several different unstiffened and blade-stiffening panel configurations, featuring both homogeneous, isotropic materials, and laminated composite material.

Determination of car on-road black carbon and particle number emission factors and comparison between mobile and stationary measurements

NASA Astrophysics Data System (ADS)

Ježek, I.; Drinovec, L.; Ferrero, L.; Carriero, M.; Močnik, G.

2015-01-01

We have used two methods for measuring emission factors (EFs) in real driving conditions on five cars in a controlled environment: the stationary method, where the investigated vehicle drives by the stationary measurement platform and the composition of the plume is measured, and the chasing method, where a mobile measurement platform drives behind the investigated vehicle. We measured EFs of black carbon and particle number concentration. The stationary method was tested for repeatability at different speeds and on a slope. The chasing method was tested on a test track and compared to the portable emission measurement system. We further developed the data processing algorithm for both methods, trying to improve consistency, determine the plume duration, limit the background influence and facilitate automatic processing of measurements. The comparison of emission factors determined by the two methods showed good agreement. EFs of a single car measured with either method have a specific distribution with a characteristic value and a long tail of super emissions. Measuring EFs at different speeds or slopes did not significantly influence the EFs of different cars; hence, we propose a new description of vehicle emissions that is not related to kinematic or engine parameters, and we rather describe the vehicle EF with a characteristic value and a super emission tail.

Standard Methods for Bolt-Bearing Testing of Textile Composites

NASA Technical Reports Server (NTRS)

Portanova, M. A.; Masters, J. E.

1995-01-01

The response of three 2-D braided materials to bolt bearing loading was evaluated using data generated by Boeing Defense and Space Group in Philadelphia, PA. Three test methods, stabilized single shear, unstabilized single shear, and double shear, were compared. In general, these textile composites were found to be sensitive to bolt bearing test methods. The stabilized single shear method yielded higher strengths than the unstabilized single shear method in all cases. The double shear test method always produced the highest strengths but these results may be somewhat misleading. It is therefore recommended that standard material comparisons be made using the stabilized single shear test method. The effects of two geometric parameters, W/D and e/D, were also studied. An evaluation of the effect of the specimen width (W) to hole diameter (D) ratio concluded that bolt bearing responses were consistent with open hole tension results. A W/D ratio of 6 or greater should be maintained. The proximity of the hole to the specimen edge significantly affected strength. In all cases, strength was improved by increasing the ratio of the distance from the hole center to the specimen edge (e) to the hole diameter (D) above 2. An e/D ratio of 3 or greater is recommended.

Comparison of two high-resolution manometry software systems in evaluating esophageal motor function.

PubMed

Rengarajan, A; Drapekin, J; Patel, A; Gyawali, C P

2016-12-01

High-resolution manometry (HRM) utilizes software tools to diagnose esophageal motor disorders. Performance of these software metrics could be affected by averaging and by software characteristics of different manufacturers. High-resolution manometry studies on 86 patients referred for antireflux surgery (61.6 ± 1.4 year, 70% F) and 20 healthy controls (27.9 ± 0.7 year, 45% F) were first subject to standard analysis (Medtronic, Duluth, GA, USA). Coordinates for each of 10 test swallows were exported and averaged to generate a composite swallow. The swallows and averaged composites were imported as ASCII file format into Manoview (Medtronic) and Medical Measurement Systems database reporter (MMS, Dover, NH, USA), and analyses repeated. Comparisons were made between standard and composite swallow interpretations. Correlation between the two systems was high for mean distal contractile integral (DCI, r 2 ≥ 0.9) but lower for integrated relaxation pressure (IRP, r 2 = 0.7). Excluding achalasia, six patients with outflow obstruction (mean IRP 23.2 ± 2.1 with 10-swallow average) were identified by both systems. An additional nine patients (10.5%) were identified as outflow obstruction (15 mmHg threshold) with MMS 10-swallow and four with MMS composite swallow evaluation; only one was confirmed. Ineffective esophageal motility was diagnosed by 10-swallow evaluation in 19 (22.1%) with Manoview, and 20 (23.3%) with MMS. On Manoview composite, 17 had DCI <450 mmHg/cm/s, and on MMS composite, 21, (p ≥ 0.85 for each comparison) but these did not impact diagnostic conclusions. Comparison of 10 swallow and composite swallows demonstrate variability in software metrics between manometry systems. Our data support use of manufacturer specific software metrics on 10-swallow sequences. © 2016 John Wiley & Sons Ltd.

Multi-slice nanostructured WS2@rGO with enhanced Li-ion battery performance and a comprehensive mechanistic investigation.

PubMed

Li, Honglin; Yu, Ke; Fu, Hao; Guo, Bangjun; Lei, Xiang; Zhu, Ziqiang

2015-11-28

A thin nanoslice structured WS2@reduced graphene oxide (rGO) composite was successfully fabricated by a facile hydrothermal synthesis method. The layered structure and morphology of the composite were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The WS2@rGO composite structure demonstrated significantly enhanced rate capability performance in comparison with pristine WS2 when used as an anode material for lithium-ion batteries (LIBs). The composite demonstrated a capacity of 565 mA h g(-1) after 100 cycles when cycled at 0.1 A g(-1) and it could still deliver a stable capacity of about 337 mA h g(-1) at 2 A g(-1). Electrochemical impedance spectroscopy (EIS) measurement showed that the synergistic effect between WS2 and rGO could remarkably reduce the contact resistance and improve the corresponding electrochemical performances. In order to analyze and interpret the corresponding results from a theoretically sound perspective, first principles calculations was further performed to investigate the corresponding inner mechanisms of pristine WS2 and WS2@graphene composite. The nudged elastic band (NEB) method was used to investigate the diffusion properties of Li in the different structures. Molecular dynamics (MD) simulation and Young's modulus calculation were further employed to explore the stability and mechanical properties of the two structures for the first time. These new perspectives pave the way for the design and fabrication of graphene-TMDs based composites as the next generation of LIB anode materials with high power density and cycling stability.

Comparison of Body Composition Measurements Using a New Caliper, Two Established Calipers, Hydrostatic Weighing, and BodPod

PubMed Central

TALBERT, ERIN E.; FLYNN, MICHAEL G.; BELL, JEFFREY W.; CARRILLO, ANDRES E.; DILL, MARQUITA D.; CHRISTENSEN, CHRISTIANIA N.; THOMPSON, COLLEEN M.

2009-01-01

Purposes (1) To compare the Lafayette Instruments (LI) skinfold caliper to the Lange (L) and Harpenden (H) calipers using a diverse subject population. (2) To determine the validity of the LI caliper in a subset of subjects by comparing body compositions from skinfold thicknesses to those measured by hydrostatic weighing (HW) and air displacement plethysmography (ADP). (3) To compare measurements obtained by experienced (EX) and inexperienced (IX) technicians using all three calipers. Methods Skinfold measurements were performed by both EX and IX technicians using three different calipers on 21 younger (21.2 ± 1.5 yrs) and 20 older (59.2 ± 4 yrs) subjects. Body compositions were calculated using the Jackson-Pollock seven-site and three-site formulas. HW and ADP tests were performed on a subset of subjects (10 younger, 10 older). Results No significant differences existed between LI and L or H when measurements were made by EX. Further, the LI-EX measurements were highly correlated to both H-EX and L-EX. No significant differences existed in the subgroup between LI-EX and HW or ADP. Skinfold determinations made by EX and IX were similar. Conclusions Similar body compositions determined using LI, H, and L suggest that LI determines body composition as effectively as H and L. High correlations between the three calipers support this notion. Similar results between LI and HW/ADP subgroup suggest that the LI caliper may be a valid method of measuring body composition. Overall, performance by IX was similar to EX and suggests similar ease of use for all three calipers. PMID:28572871

A study of the electrical properties of carbon nanofiber polymer composites

NASA Astrophysics Data System (ADS)

Cardoso, Paulo Jorge Magalhaes

The interest of industry on using carbon nanofibers (CNF) as a possible alternative to carbon nanotubes (CNT) to produce polymer based composites is due to their lower price, the ability to be produced in large amounts and the their usefulness as a reinforcement filler in order to improve the matrix properties such as mechanical, thermal and electrical. Polymers like epoxy resins already have good-to-excellent properties and an extensive range of applications, but the reinforcement with fillers like CNF, which has high aspect ratio (AR) and surface energy, has the potential to extend the range of applications. The Van der Waals interactions between nanofillers, such as CNF, promote the clustering effect which affects their dispersion in the polymer and may interfere with some properties of the nanocomposites. In this sense, it is very important to use appropriate dispersion methods which are able to disentangle the nanofillers to a certain degree, but avoiding the reduction of the nanofibers AR as much as possible. In fact, the methods and conditions of nanocomposites processing have also influence on the filler orientation, dispersion, distribution and aspect ratio. To the present day, there is a lack of complete information in the literature about the relation between structure and properties, in particular electrical properties, for polymer nanocomposites. The main objective of this work is to study the electrical properties of composites based on CNF and epoxy resin using production methods which can be easily implemented in industrial environments and that provide different dispersion levels, investigating therefore the relationship between dispersion level and electrical response. Some of the requirements for such methods are the adaptability to the industrial processes and facilities which allow large scale productions and provide a good relation between quality and cost of the composite materials. In this work, morphological, electrical and electromechanical studies were performed in epoxy resin composites with vapor-grown carbon nanofibers (VGCNF). First, the electrical properties of VGCNF/epoxy resin composites produced with a simple method were studied. Then, it was investigated the relation between the electrical properties and the dispersion level of VGCNF/epoxy composites produced with different methods, which were selected to provide different levels of dispersion.The level of nanofiber dispersion of the composites produced with the different methods and filler contents was analyzed by transmission optical microscopy (TOM) and greyscale analysis (GSA) and then compared to the electrical conductivity measurements. After this study, the influence of different methods of VGCNF dispersion on the electrical conduction mechanism of the composites was investigated. Then, these composites were submitted to electromechanical tests in order to apply them as piezoresistive sensors. The last study of this work was dedicated to an initial comparison between the epoxy composites with VGCNG and multi-walled carbon nanotubes (MWCNT), in terms of electrical and morphological properties. As the main outcomes of the present work, it can be concluded that a better cluster dispersion seems to be more suitable than good filler dispersion for achieving larger electrical conductivities and lower percolation thresholds. It is also concluded that hopping conductivity is a relevant mechanism for determining the overall conductivity of the composites and that the CNF/epoxy composites are appropriate materials for piezoresistive sensors in particular at concentrations close to the percolation threshold.

An X-ray diffraction method for semiquantitative mineralogical analysis of Chilean nitrate ore

USGS Publications Warehouse

Jackson, J.C.; Ericksent, G.E.

1997-01-01

Computer analysis of X-ray diffraction (XRD) data provides a simple method for determining the semiquantitative mineralogical composition of naturally occurring mixtures of saline minerals. The method herein described was adapted from a computer program for the study of mixtures of naturally occurring clay minerals. The program evaluates the relative intensities of selected diagnostic peaks for the minerals in a given mixture, and then calculates the relative concentrations of these minerals. The method requires precise calibration of XRD data for the minerals to be studied and selection of diffraction peaks that minimize inter-compound interferences. The calculated relative abundances are sufficiently accurate for direct comparison with bulk chemical analyses of naturally occurring saline mineral assemblages.

An x-ray diffraction method for semiquantitative mineralogical analysis of chilean nitrate ore

USGS Publications Warehouse

John, C.; George, J.; Ericksen, E.

1997-01-01

Computer analysis of X-ray diffraction (XRD) data provides a simple method for determining the semiquantitative mineralogical composition of naturally occurring mixtures of saline minerals. The method herein described was adapted from a computer program for the study of mixtures of naturally occurring clay minerals. The program evaluates the relative intensities of selected diagnostic peaks for the minerals in a given mixture, and then calculates the relative concentrations of these minerals. The method requires precise calibration of XRD data for the minerals to be studied and selection of diffraction peaks that minimize inter-compound interferences. The calculated relative abundances are sufficiently accurate for direct comparison with bulk chemical analyses of naturally occurring saline mineral assemblages.

Characterization of an improved 1-3 piezoelectric composite by simulation and experiment.

PubMed

Zhong, Chao; Wang, Likun; Qin, Lei; Zhang, Yanjun

2017-06-16

To increase electromechanical coupling factor of 1-3 piezoelectric composite and reduce its bending deformation under external stress, an improved 1-3 piezoelectric composite is developed. In the improved structure, both epoxy resin and silicone rubber are used as polymer material. The simulation model of the improved 1-3 piezoelectric composite was established using the finite element software ANSYS. The relationship of the performance of the improved composite to the volume percentage of silicone rubber was determined by harmonic response analysis and the bending deformation under external stress was simulated by static analysis. The improved composite samples were prepared by cutting and filling methods, and the performance was tested. The feasibility of the improved structure was verified by finite element simulation and experiment. The electromechanical coupling factor of the improved composite can reach 0.67 and meanwhile the characteristic impedance can decline to 13 MRayl. The electromechanical coupling factor of the improved composite is higher than that of the composite with only epoxy resin as the polymer and the improved composite can reduce bending deformation. Comparison of simulation and experiment, the results of the experiment are in general agreement with those from the simulation. However, most experimental values were higher than the simulation results, and the abnormality of the test results was also more obvious than that of the simulation. These findings may be attributed to slight difference in the material parameters of simulation and experiment.

Analysis of a new composite material for watercraft manufacturing

NASA Astrophysics Data System (ADS)

Wahrhaftig, Alexandre; Ribeiro, Henrique; Nascimento, Ademar; Filho, Milton

2016-09-01

In this paper, we investigate the properties of an alternative material for use in marine engineering, namely a rigid and light sandwich-structured composite made of expanded polystyrene and fiberglass. Not only does this material have an improved section modulus, but it is also inexpensive, light, easy to manipulate, and commercially available in various sizes. Using a computer program based on the finite element method, we calculated the hogging and sagging stresses and strains acting on a prismatic boat model composed of this material, and determined the minimum sizes and maximum permissible stresses to avoid deformation. Finally, we calculated the structural weight of the resulting vessel for comparison with another structure of comparable dimensions constructed from the commonly used core material Divinycell.

An improved model for the combustion of AP composite propellants

NASA Technical Reports Server (NTRS)

Cohen, N. S.; Strand, L. D.

1981-01-01

This paper presents several improvements to the BDP model of steady-state burning of AP composite solid propellants. The Price-Boggs-Derr model of AP monopropellant burning is incorporated to represent the AP. A separate energy equation is written for the binder to permit a different surface temperature from the AP; this includes an analysis of the sharing of primary diffusion flame energy, and correction of a BDP model inconsistency in treating the binder regression rate. A method for assembling component contributions to calculate the burning rates of multimodal propellants is also presented. Results are shown in the form of representative burning rate curves, comparisons with data, and calculated internal details of interest. Ideas for future work are discussed in an Appendix.

Comparison of various tool wear prediction methods during end milling of metal matrix composite

NASA Astrophysics Data System (ADS)

Wiciak, Martyna; Twardowski, Paweł; Wojciechowski, Szymon

2018-02-01

In this paper, the problem of tool wear prediction during milling of hard-to-cut metal matrix composite Duralcan™ was presented. The conducted research involved the measurements of acceleration of vibrations during milling with constant cutting conditions, and evaluation of the flank wear. Subsequently, the analysis of vibrations in time and frequency domain, as well as the correlation of the obtained measures with the tool wear values were conducted. The validation of tool wear diagnosis in relation to selected diagnostic measures was carried out with the use of one variable and two variables regression models, as well as with the application of artificial neural networks (ANN). The comparative analysis of the obtained results enable.

Hybrid Particle-Element Simulation of Impact on Composite Orbital Debris Shields

NASA Technical Reports Server (NTRS)

Fahrenthold, Eric P.

2004-01-01

This report describes the development of new numerical methods and new constitutive models for the simulation of hypervelocity impact effects on spacecraft. The research has included parallel implementation of the numerical methods and material models developed under the project. Validation work has included both one dimensional simulations, for comparison with exact solutions, and three dimensional simulations of published hypervelocity impact experiments. The validated formulations have been applied to simulate impact effects in a velocity and kinetic energy regime outside the capabilities of current experimental methods. The research results presented here allow for the expanded use of numerical simulation, as a complement to experimental work, in future design of spacecraft for hypervelocity impact effects.

Application of single- and dual-energy CT brain tissue segmentation to PET monitoring of proton therapy

NASA Astrophysics Data System (ADS)

Berndt, Bianca; Landry, Guillaume; Schwarz, Florian; Tessonnier, Thomas; Kamp, Florian; Dedes, George; Thieke, Christian; Würl, Matthias; Kurz, Christopher; Ganswindt, Ute; Verhaegen, Frank; Debus, Jürgen; Belka, Claus; Sommer, Wieland; Reiser, Maximilian; Bauer, Julia; Parodi, Katia

2017-03-01

The purpose of this work was to evaluate the ability of single and dual energy computed tomography (SECT, DECT) to estimate tissue composition and density for usage in Monte Carlo (MC) simulations of irradiation induced β + activity distributions. This was done to assess the impact on positron emission tomography (PET) range verification in proton therapy. A DECT-based brain tissue segmentation method was developed for white matter (WM), grey matter (GM) and cerebrospinal fluid (CSF). The elemental composition of reference tissues was assigned to closest CT numbers in DECT space (DECTdist). The method was also applied to SECT data (SECTdist). In a validation experiment, the proton irradiation induced PET activity of three brain equivalent solutions (BES) was compared to simulations based on different tissue segmentations. Five patients scanned with a dual source DECT scanner were analyzed to compare the different segmentation methods. A single magnetic resonance (MR) scan was used for comparison with an established segmentation toolkit. Additionally, one patient with SECT and post-treatment PET scans was investigated. For BES, DECTdist and SECTdist reduced differences to the reference simulation by up to 62% when compared to the conventional stoichiometric segmentation (SECTSchneider). In comparison to MR brain segmentation, Dice similarity coefficients for WM, GM and CSF were 0.61, 0.67 and 0.66 for DECTdist and 0.54, 0.41 and 0.66 for SECTdist. MC simulations of PET treatment verification in patients showed important differences between DECTdist/SECTdist and SECTSchneider for patients with large CSF areas within the treatment field but not in WM and GM. Differences could be misinterpreted as PET derived range shifts of up to 4 mm. DECTdist and SECTdist yielded comparable activity distributions, and comparison of SECTdist to a measured patient PET scan showed improved agreement when compared to SECTSchneider. The agreement between predicted and measured PET activity distributions was improved by employing a brain specific segmentation applicable to both DECT and SECT data.

Biocompatibility of NGF-grafted GTG membranes for peripheral nerve repair using cultured Schwann cells.

PubMed

Chen, Pei-Ru; Chen, Ming-Hong; Sun, Jui-Sheng; Chen, Mei-Hsiu; Tsai, Chien-Chen; Lin, Feng-Huei

2004-11-01

We previously developed a biodegradable composite with potentially good biocompatibility composed by tricalcium phosphate and gluataraldehyde cross-linking gelatin (GTG) with good mechanical property feasible for surgical manipulation. The purpose of this study was to evaluate the feasibility of immobilizing nerve growth factor (NGF) onto the composite (GTG) with carbodiimide (GEN composite). Cultured Schwann cells were seeded onto the GTG and GEN composites. For comparison, GTG membrane soaked in NGF solution without carbodiimide (GN composite) as cross-linking agent was also used to culture Schwann cells. Cell morphology was observed by a scanning electron microscope. Cell survival, cytotoxicity and cellular metabolism on the NGF-grafted GTG membrane were assessed quantitatively in terms of cell protein content, leakage of cytosolic lactate dehydrogenase (LDH) activity and by the well-established MTT assay, respectively. The result of LDH study did not show significant difference among GTG, NGF-modified GTG and control group. This indicated that GTG composite, whether cross-linking with NGF or not, has little cytotoxic effect. Comparing the protein content and MTT assay among GEN, GN composite and control group, the data confirmed more attachment of Schwann cells on GEN composite. Although GTG cross-linking with NGF did not promote Schwann cell proliferation, the techniques we used in this study provided a method to fabricate a novel biomaterial incorporation of Schwann cells and covalently immobilized NGF.

Assessing the composition of fragmented agglutinated foraminiferal assemblages in ancient sediments: comparison of counting and area-based methods in Famennian samples (Late Devonian)

NASA Astrophysics Data System (ADS)

Girard, Catherine; Dufour, Anne-Béatrice; Charruault, Anne-Lise; Renaud, Sabrina

2018-01-01

Benthic foraminifera have been used as proxies for various paleoenvironmental variables such as food availability, carbon flux from surface waters, microhabitats, and indirectly water depth. Estimating assemblage composition based on morphotypes, as opposed to genus- or species-level identification, potentially loses important ecological information but opens the way to the study of ancient time periods. However, the ability to accurately constrain benthic foraminiferal assemblages has been questioned when the most abundant foraminifera are fragile agglutinated forms, particularly prone to fragmentation. Here we test an alternate method for accurately estimating the composition of fragmented assemblages. The cumulated area per morphotype method is assessed, i.e., the sum of the area of all tests or fragments of a given morphotype in a sample. The percentage of each morphotype is calculated as a portion of the total cumulated area. Percentages of different morphotypes based on counting and cumulated area methods are compared one by one and analyzed using principal component analyses, a co-inertia analysis, and Shannon diversity indices. Morphotype percentages are further compared to an estimate of water depth based on microfacies description. Percentages of the morphotypes are not related to water depth. In all cases, counting and cumulated area methods deliver highly similar results, suggesting that the less time-consuming traditional counting method may provide robust estimates of assemblages. The size of each morphotype may deliver paleobiological information, for instance regarding biomass, but should be considered carefully due to the pervasive issue of fragmentation.

Reusable electrochemical sensor for bisphenol A based on ionic liquid functionalized conducting polymer platform.

PubMed

Wang, Jhe-Yi; Su, Ya-Ling; Wu, Bo-Hao; Cheng, Shu-Hua

2016-01-15

The toxicity of bisphenol A (BPA) has attracted considerable attention, and the reported electrochemical sensors for BPA need further improvement in reusability due to serious surface fouling. In this study, a composite film is designed aiming to provide both an accurate and repeatable platform for BPA determination. The conducting poly(3,4-ethylenedioxythiophene) film (PEDOT) and ionic liquid 1-butyl-3-methylimidazolium bromide (BMIMBr) were modified onto screen-printed carbon electrodes (SPCE) by electropolymerization and drop/spin methods, respectively. The surface characteristics of the composite film were characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and surface water contact angle experiments. The composite film-modified electrodes exhibited a linear response to BPA in the range of 0.1-500µM in pH 7.0 phosphate buffer solution (PBS) under optimized flow-injection amperometry. The method sensitivity and detection limit (S/N=3) were 0.2661μA μM(-1) (2.419μA μM(-1)cm(-2)) and 0.02µM, respectively. A relative standard deviation of 1.95% was obtained for 77 successive measurements of 10µM BPA, and the repeatability outperformed previously reported work. The proposed method was applied to detect BPA released from plastic water bottles using the standard addition method, and satisfactory recoveries were obtained. The electrochemical assay was validated by comparison with the chromatographic method, and the results showed good agreement between the two methods. Copyright © 2015 Elsevier B.V. All rights reserved.

Simple Statistical Model to Quantify Maximum Expected EMC in Spacecraft and Avionics Boxes

NASA Technical Reports Server (NTRS)

Trout, Dawn H.; Bremner, Paul

2014-01-01

This study shows cumulative distribution function (CDF) comparisons of composite a fairing electromagnetic field data obtained by computational electromagnetic 3D full wave modeling and laboratory testing. Test and model data correlation is shown. In addition, this presentation shows application of the power balance and extention of this method to predict the variance and maximum exptected mean of the E-field data. This is valuable for large scale evaluations of transmission inside cavities.

Estimation of leaf traits from reflectance measurements: comparison between methods based on vegetation indices and several versions of the PROSPECT model.

PubMed

Jiang, Jingyi; Comar, Alexis; Burger, Philippe; Bancal, Pierre; Weiss, Marie; Baret, Frédéric

2018-01-01

Leaf biochemical composition corresponds to traits related to the plant state and its functioning. This study puts the emphasis on the main leaf absorbers: chlorophyll a and b ([Formula: see text]), carotenoids ([Formula: see text]), water ([Formula: see text]) and dry mater ([Formula: see text]) contents. Two main approaches were used to estimate [[Formula: see text] [Formula: see text], [Formula: see text], [Formula: see text

Elemental composition, isotopes, electrons and positrons in cosmic rays

NASA Technical Reports Server (NTRS)

Balasubrahmanyan, V. K.

1979-01-01

Papers presented at the 16th International Cosmic Ray Conference, Kyoto, Japan, dealing with the composition of cosmic rays are reviewed. Particular interest is given to data having bearing on nucleosynthesis sites, supernovae, gamma-process, comparison with solar system composition, multiplicity of sources, and the energy dependence of composition.

[FQA: A method for floristic quality assessment based on conservatism of plant species].

PubMed

Cao, Li Juan; He, Ping; Wang, Mi; Xui, Jie; Ren, Ying

2018-04-01

FQA, which uses the conservatism of plant species for particular habitats and the species richness of plant communities, is a rapid method for the assessment of habitat quality. This method is based on species composition of quadrats and coefficients of conservatism for species which assigned by experts. Floristic Quality Index (FQI) that reflects vegetation integrity and degradation of a site can be calculated by a simple formula and be used for space-time comparison of habitat quality. It has been widely used in more than ten countries including the United States and Canada. This paper presented the principle, calculation formulas and application cases of this method, with the aim to provide a simple, repeatable and comparable method to assess habitat quality for ecological managers and researchers.

Comparisons of Lagrangian and Eulerian PDF methods in simulations of non-premixed turbulent jet flames with moderate-to-strong turbulence-chemistry interactions

NASA Astrophysics Data System (ADS)

Jaishree, J.; Haworth, D. C.

2012-06-01

Transported probability density function (PDF) methods have been applied widely and effectively for modelling turbulent reacting flows. In most applications of PDF methods to date, Lagrangian particle Monte Carlo algorithms have been used to solve a modelled PDF transport equation. However, Lagrangian particle PDF methods are computationally intensive and are not readily integrated into conventional Eulerian computational fluid dynamics (CFD) codes. Eulerian field PDF methods have been proposed as an alternative. Here a systematic comparison is performed among three methods for solving the same underlying modelled composition PDF transport equation: a consistent hybrid Lagrangian particle/Eulerian mesh (LPEM) method, a stochastic Eulerian field (SEF) method and a deterministic Eulerian field method with a direct-quadrature-method-of-moments closure (a multi-environment PDF-MEPDF method). The comparisons have been made in simulations of a series of three non-premixed, piloted methane-air turbulent jet flames that exhibit progressively increasing levels of local extinction and turbulence-chemistry interactions: Sandia/TUD flames D, E and F. The three PDF methods have been implemented using the same underlying CFD solver, and results obtained using the three methods have been compared using (to the extent possible) equivalent physical models and numerical parameters. Reasonably converged mean and rms scalar profiles are obtained using 40 particles per cell for the LPEM method or 40 Eulerian fields for the SEF method. Results from these stochastic methods are compared with results obtained using two- and three-environment MEPDF methods. The relative advantages and disadvantages of each method in terms of accuracy and computational requirements are explored and identified. In general, the results obtained from the two stochastic methods (LPEM and SEF) are very similar, and are in closer agreement with experimental measurements than those obtained using the MEPDF method, while MEPDF is the most computationally efficient of the three methods. These and other findings are discussed in detail.

Association of Cesarean Delivery and Formula Supplementation With the Intestinal Microbiome of 6-Week-Old Infants.

PubMed

Madan, Juliette C; Hoen, Anne G; Lundgren, Sara N; Farzan, Shohreh F; Cottingham, Kathryn L; Morrison, Hilary G; Sogin, Mitchell L; Li, Hongzhe; Moore, Jason H; Karagas, Margaret R

2016-03-01

The intestinal microbiome plays a critical role in infant development, and delivery mode and feeding method (breast milk vs formula) are determinants of its composition. However, the importance of delivery mode beyond the first days of life is unknown, and studies of associations between infant feeding and microbiome composition have been generally limited to comparisons between exclusively breastfed and formula-fed infants, with little consideration given to combination feeding of both breast milk and formula. To examine the associations of delivery mode and feeding method with infant intestinal microbiome composition at approximately 6 weeks of life. Prospective observational study of 102 infants followed up as part of a US pregnancy cohort study. Delivery mode was abstracted from delivery medical records, and feeding method prior to the time of stool collection was ascertained through detailed questionnaires. Stool microbiome composition was characterized using next-generation sequencing of the 16S rRNA gene. There were 102 infants (mean gestational age, 39.7 weeks; range, 37.1-41.9 weeks) included in this study, of whom 70 were delivered vaginally and 32 by cesarean delivery. In the first 6 weeks of life, 70 were exclusively breastfed, 26 received combination feeding, and 6 were exclusively formula fed. We identified independent associations between microbial community composition and both delivery mode (P< .001; Q < .001) and feeding method (P = .01; Q < .001). Differences in microbial community composition between vaginally delivered infants and infants delivered by cesarean birth were equivalent to or significantly larger than those between feeding groups (P = .003). Bacterial communities associated with combination feeding were more similar to those associated with exclusive formula feeding than exclusive breastfeeding (P = .002). We identified 6 individual bacterial genera that were differentially abundant between delivery mode and feeding groups. The infant intestinal microbiome at approximately 6 weeks of age is significantly associated with both delivery mode and feeding method, and the supplementation of breast milk feeding with formula is associated with a microbiome composition that resembles that of infants who are exclusively formula fed. These results may inform feeding choices and shed light on the mechanisms behind the lifelong health consequences of delivery and infant feeding modalities.

Comparison of large-insert, small-insert and pyrosequencing libraries for metagenomic analysis.

PubMed

Danhorn, Thomas; Young, Curtis R; DeLong, Edward F

2012-11-01

The development of DNA sequencing methods for characterizing microbial communities has evolved rapidly over the past decades. To evaluate more traditional, as well as newer methodologies for DNA library preparation and sequencing, we compared fosmid, short-insert shotgun and 454 pyrosequencing libraries prepared from the same metagenomic DNA samples. GC content was elevated in all fosmid libraries, compared with shotgun and 454 libraries. Taxonomic composition of the different libraries suggested that this was caused by a relative underrepresentation of dominant taxonomic groups with low GC content, notably Prochlorales and the SAR11 cluster, in fosmid libraries. While these abundant taxa had a large impact on library representation, we also observed a positive correlation between taxon GC content and fosmid library representation in other low-GC taxa, suggesting a general trend. Analysis of gene category representation in different libraries indicated that the functional composition of a library was largely a reflection of its taxonomic composition, and no additional systematic biases against particular functional categories were detected at the level of sequencing depth in our samples. Another important but less predictable factor influencing the apparent taxonomic and functional library composition was the read length afforded by the different sequencing technologies. Our comparisons and analyses provide a detailed perspective on the influence of library type on the recovery of microbial taxa in metagenomic libraries and underscore the different uses and utilities of more traditional, as well as contemporary 'next-generation' DNA library construction and sequencing technologies for exploring the genomics of the natural microbial world.

Finite Element Analysis of Poroelastic Composites Undergoing Thermal and Gas Diffusion

NASA Technical Reports Server (NTRS)

Salamon, N. J. (Principal Investigator); Sullivan, Roy M.; Lee, Sunpyo

1995-01-01

A theory for time-dependent thermal and gas diffusion in mechanically time-rate-independent anisotropic poroelastic composites has been developed. This theory advances previous work by the latter two authors by providing for critical transverse shear through a three-dimensional axisymmetric formulation and using it in a new hypothesis for determining the Biot fluid pressure-solid stress coupling factor. The derived governing equations couple material deformation with temperature and internal pore pressure and more strongly couple gas diffusion and heat transfer than the previous theory. Hence the theory accounts for the interactions between conductive heat transfer in the porous body and convective heat carried by the mass flux through the pores. The Bubnov Galerkin finite element method is applied to the governing equations to transform them into a semidiscrete finite element system. A numerical procedure is developed to solve the coupled equations in the space and time domains. The method is used to simulate two high temperature tests involving thermal-chemical decomposition of carbon-phenolic composites. In comparison with measured data, the results are accurate. Moreover unlike previous work, for a single set of poroelastic parameters, they are consistent with two measurements in a restrained thermal growth test.

Comparison of Hard Surface and Soft Soil Impact Performance of a Crashworthy Composite Fuselage Concept

NASA Technical Reports Server (NTRS)

Sareen, Ashish K.; Sparks, Chad; Mullins, B. R., Jr.; Fasanella, Edwin; Jackson, Karen

2002-01-01

A comparison of the soft soil and hard surface impact performance of a crashworthy composite fuselage concept has been performed. Specifically, comparisons of the peak acceleration values, pulse duration, and onset rate at specific locations on the fuselage were evaluated. In a prior research program, the composite fuselage section was impacted at 25 feet per second onto concrete at the Impact Dynamics Research Facility (IDRF) at NASA Langley Research Center. A soft soil test was conducted at the same impact velocity as a part of the NRTC/RITA Crashworthy and Energy Absorbing Structures project. In addition to comparisons of soft soil and hard surface test results, an MSC. Dytran dynamic finite element model was developed to evaluate the test analysis correlation. In addition, modeling parameters and techniques affecting test analysis correlation are discussed. Once correlated, the analytical methodology will be used in follow-on work to evaluate the specific energy absorption of various subfloor concepts for improved crash protection during hard surface and soft soil impacts.

Spacecraft measurements of the elemental and isotopic composition of solar energetic particles

NASA Technical Reports Server (NTRS)

Mewaldt, R. A.

1980-01-01

Within the past few years, instruments flown on satellites and space probes have made significant progress in measuring the elemental and isotopic composition of energetic heavy nuclei accelerated in solar flares. These new observations are discussed, focusing on: (1) the energy dependence of the elemental composition at energies not greater than 1 MeV/nucleon; (2) flare to flare variations in the composition; and (3) comparisons of the average solar particle abundances (Z not less than 2 and not greater than 28) with other measures of the solar composition, including photospheric, coronal, and solar wind observations. These comparisons have led to the suggestion that solar flares sample the composition of the corona. Isotopic measurements of heavy solar flare nuclei have recently added a new dimension to these studies. In particular, the isotopic composition of solar flare neon has been found to be significantly different from that measured in the solar wind, but consistent with the meteoritic component neon-A.

New approaches for the chemical and physical characterization of aerosols using a single particle mass spectrometry based technique

NASA Astrophysics Data System (ADS)

Spencer, Matthew Todd

Aerosols affect the lives of people every day. They can decrease visibility, alter cloud formation and cloud lifetimes, change the energy balance of the earth and are implicated in causing numerous health problems. Measuring the physical and chemical properties of aerosols is essential to understand and mitigate any negative impacts that aerosols might have on climate and human health. Aerosol time-of-flight mass spectrometry (ATOFMS) is a technique that measures the size and chemical composition of individual particles in real time. The goal of this dissertation is to develop new and useful approaches for measuring the physical and/or chemical properties of particles using ATOFMS. This has been accomplished using laboratory experiments, ambient field measurements and sometimes comparisons between them. A comparison of mass spectra generated from petrochemical particles was made to light duty vehicle (LDV) and heavy duty diesel vehicle (HDDV) particle mass spectra. This comparison has given us new insight into how to differentiate between particles from these two sources. A method for coating elemental carbon (EC) particles with organic carbon (OC) was used to generate a calibration curve for quantifying the fraction of organic carbon and elemental carbon on particles using ATOFMS. This work demonstrates that it is possible to obtain quantitative chemical information with regards to EC and OC using ATOFMS. The relationship between electrical mobility diameter and aerodynamic diameter is used to develop a tandem differential mobility analyzer-ATOFMS technique to measure the effective density, size and chemical composition of particles. The method is applied in the field and gives new insight into the physical/chemical properties of particles. The size resolved chemical composition of aerosols was measured in the Indian Ocean during the monsoonal transition period. This field work shows that a significant fraction of aerosol transported from India was from biomass burning and appeared to be internally mixed with sulfate which suggests it was cloud processed during transport. Lastly, noble metal nanoparticles are explored as potential matrices for visible wavelength single particle matrix assisted laser desorption/ionization mass spectrometry (VIS-MALDI). This work demonstrates that noble metal nanoparticle matrices can be used for VIS-MALDI analysis.

Determination of the Shear Stress Distribution in a Laminate from the Applied Shear Resultant--A Simplified Shear Solution

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.

2007-01-01

The simplified shear solution method is presented for approximating the through-thickness shear stress distribution within a composite laminate based on laminated beam theory. The method does not consider the solution of a particular boundary value problem, rather it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply level stresses can be efficiently determined from global load resultants (as determined, for instance, by finite element analysis) at a given location in a structure and used to evaluate the margin of safety on a ply by ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. Comparisons to existing theories are made for a variety of laminates, and design examples are provided illustrating the use of the method for determining through-thickness shear stress margins in several types of composite panels and in the context of a finite element structural analysis.

Comparison of different methods for extraction from Tetraclinis articulata: yield, chemical composition and antioxidant activity.

PubMed

Herzi, Nejia; Bouajila, Jalloul; Camy, Séverine; Romdhane, Mehrez; Condoret, Jean-Stéphane

2013-12-15

In the present study, three techniques of extraction: hydrodistillation (HD), solvent extraction (conventional 'Soxhlet' technique) and an innovative technique, i.e., the supercritical fluid extraction (SFE), were applied to ground Tetraclinis articulata leaves and compared for extraction duration, extraction yield, and chemical composition of the extracts as well as their antioxidant activities. The extracts were analyzed by GC-FID and GC-MS. The antioxidant activity was measured using two methods: ABTS(•+) and DPPH(•). The yield obtained using HD, SFE, hexane and ethanol Soxhlet extractions were found to be 0.6, 1.6, 40.4 and 21.2-27.4 g/kg respectively. An original result of this study is that the best antioxidant activity was obtained with an SFE extract (41 mg/L). The SFE method offers some noteworthy advantages over traditional alternatives, such as shorter extraction times, low environmental impact, and a clean, non-thermally-degraded final product. Also, a good correlation between the phenolic contents and the antioxidant activity was observed with extracts obtained by SFE at 9 MPa. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fast determination of Ziziphora tenuior L. essential oil by inorganic-organic hybrid material based on ZnO nanoparticles anchored to a composite made from polythiophene and hexagonally ordered silica.

PubMed

Piryaei, Marzieh; Abolghasemi, Mir Mahdi; Nazemiyeh, Hossein

2015-01-01

In this paper, for the first time, an inorganic-organic hybrid material based on ZnO nanoparticles was anchored to a composite made from polythiophene and hexagonally ordered silica (ZnO/PT/SBA-15) for use in solid-phase fibre microextraction (SPME) of medicinal plants. A homemade SPME apparatus was used for the extraction of volatile components of Ziziphora tenuior L. A simplex method was used for optimisation of five different parameters affecting the efficiency of the extraction. The main constituents extracted by ZnO/PT/SBA-15 and PDMS fibres and hydrodistillation (HD) methods, respectively, included pulegone (51.25%, 53.64% and 56.68%), limonene (6.73%, 6.58% and 8.3%), caryophyllene oxide (5.33%, 4.31% and 4.53%) and 1,8-cineole (4.21%, 3.31% and 3.18%). In comparison with the HD method, the proposed technique could equally monitor almost all the components of the sample, in an easier way, in a shorter time and requiring a much lower amount of the sample.

Damage detection in sandwich composite materials using laser vibrometry in conjunction with nonlinear system identification

NASA Astrophysics Data System (ADS)

Underwood, Sara; Koester, David; Adams, Douglas E.

2009-03-01

Fiberglass sandwich panels are tested to study a vibration-based method for locating damage in composite materials. This method does not rely on a direct comparison of the natural frequencies, mode shapes, or residues in the forced vibration response data. Specifically, a nonlinear system identification based method for damage detection is sought that reduces the sensitivity of damage detection results to changes in vibration measurements due to variations in boundary conditions, environmental conditions, and material properties of the panel. Damage mechanisms considered include a disbond between the core and face sheet and a crack within the core. A panel is excited by a skewed piezoelectric actuator over a broad frequency range while a three-dimensional scanning laser vibrometer measures the surface velocity of the panel along three orthogonal axes. The forced frequency response data measured using the scanning laser vibrometer at multiple excitation amplitudes is processed to identify areas of the panel that exhibit significant nonlinear response characteristics. It is demonstrated that these localized nonlinearities in the panel coincide with the damaged areas of the composite material. Because changes in the measured frequency response functions due to nonlinear distortions associated with the damage can be identified without comparing the vibration data to a reference (baseline) signature of the undamaged material, this vibration technique for damage detection in composite materials exhibits less sensitivity to variations in the underlying linear characteristics than traditional methods. It is also demonstrated that the damage at a given location can be classified as either due to a disbond or core crack because these two types of damage produce difference signatures when comparing the multi-amplitude frequency response functions.

Model to Test Electric Field Comparisons in a Composite Fairing Cavity

NASA Technical Reports Server (NTRS)

Trout, Dawn; Burford, Janessa

2012-01-01

Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This study shows cumulative distribution function (CDF) comparisons of composite . a fairing electromagnetic field data obtained by computational electromagnetic 3D full wave modeling and laboratory testing. This work is an extension of the bare aluminum fairing perfect electric conductor (PEC) model. Test and model data correlation is shown.

Model to Test Electric Field Comparisons in a Composite Fairing Cavity

NASA Technical Reports Server (NTRS)

Trout, Dawn H.; Burford, Janessa

2013-01-01

Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This study shows cumulative distribution function (CDF) comparisons of composite a fairing electromagnetic field data obtained by computational electromagnetic 3D full wave modeling and laboratory testing. This work is an extension of the bare aluminum fairing perfect electric conductor (PEC) model. Test and model data correlation is shown.

Nonlinear deformation of composites with consideration of the effect of couple-stresses

NASA Astrophysics Data System (ADS)

Lagzdiņš, A.; Teters, G.; Zilaucs, A.

1998-09-01

Nonlinear deformation of spatially reinforced composites under active loading (without unloading) is considered. All the theoretical constructions are based on the experimental data on unidirectional and ±π/4 cross-ply epoxy plastics reinforced with glass fibers. Based on the elastic properties of the fibers and EDT-10 epoxy binder, the linear elastic characteristics of a transversely isotropic unidirectionally reinforced fiberglass plastic are found, whereas the nonlinear characteristics are obtained from experiments. For calculating the deformation properties of the ±π/4 cross-ply plastic, a refined version of the Voigt method is applied taking into account also the couple-stresses arising in the composite due to relative rotation of the reinforcement fibers. In addition, a fourth-rank damage tensor is introduced in order to account for the impact of fracture caused by the couple-stresses. The unknown constants are found from the experimental uniaxial tension curve for the cross-ply composite. The comparison between the computed curves and experimental data for other loading paths shows that the description of the nonlinear behavior of composites can be improved by considering the effect of couple-stresses generated by rotations of the reinforcing fibers.

AgBr/MgBi2O6 heterostructured composites with highly efficient visible-light-driven photocatalytic activity

NASA Astrophysics Data System (ADS)

Zhong, Liansheng; Hu, Chaohao; Zhuang, Jing; Zhong, Yan; Wang, Dianhui; Zhou, Huaiying

2018-06-01

AgBr/MgBi2O6 heterostructured photocatalysts were synthesized by the deposition-precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed to examine the phase structure, morphology and optical properties of the as-prepared samples. The photocatalytic activity was investigated by decomposing methylene blue (MB) solution under visible light irradiation (λ > 420 nm). AgBr/MgBi2O6 composites exhibited significantly enhanced visible-light-driven photocatalytic properties in comparison with pure MgBi2O6 and AgBr. When the molar ratio of AgBr to MgBi2O6 was 3:1, the composite catalyst showed the optimal photocatalytic activity and excellent stability. The enhanced photocatalytic activity of AgBr/MgBi2O6 composites was attributed to the formation of p-n heterojunction between AgBr and MgBi2O6, thereby resulting in the effective separation and transfer of photogenerated electrons-hole pairs.

Comparison of helicopter and ground surveys for North American elk Cervus elaphus and mule deer Odocoileus hemionus population composition

USGS Publications Warehouse

Bender, L.C.; Myers, W.L.; Gould, W.R.

2003-01-01

Both ground and helicopter surveys are commonly used to collect sex and age composition data for ungulates. Little attention has been paid, however, to whether data collected by each technique are similar. We compared helicopter and ground composition data for both elk Cervus elaphus and mule deer Odocoileus hemionus across a variety of habitats in the state of Washington, USA. We found that ground and helicopter counts differed (P's < 0.002) consistently in male age structure estimates for elk, and that the two survey methods differed in estimates of adult sex ratios for mule deer (P = 0.023). Counts from helicopters provided larger sample sizes, tended to be more consistent annually in their results, and were corroborated by other demographic studies of the test populations. We conclude that helicopter and ground surveys differ for male age structure and perhaps male:female ratios, but are similar for young:female ratios. Managers should maintain a standardized technique using the same survey vehicle for trend analysis of composition data.

Synthesis and Characterization of Nano Boron Nitride Reinforced Magnesium Composites Produced by the Microwave Sintering Method

PubMed Central

Seetharaman, Sankaranarayanan; Subramanian, Jayalakshmi; Tun, Khin Sandar; Hamouda, Abdelmagid S.; Gupta, Manoj

2013-01-01

In this study, magnesium composites with nano-size boron nitride (BN) particulates of varying contents were synthesized using the powder metallurgy (PM) technique incorporating microwave-assisted two-directional sintering followed by hot extrusion. The effect of nano-BN addition on the microstructural and the mechanical behavior of the developed Mg/BN composites were studied in comparison with pure Mg using the structure-property correlation. Microstructural characterization revealed uniform distribution of nano-BN particulates and marginal grain refinement. The coefficient of thermal expansion (CTE) value of the magnesium matrix was improved with the addition of nano-sized BN particulates. The results of XRD studies indicate basal texture weakening with an increase in nano-BN addition. The composites showed improved mechanical properties measured under micro-indentation, tension and compression loading. While the tensile yield strength improvement was marginal, a significant increase in compressive yield strength was observed. This resulted in the reduction of tension-compression yield asymmetry and can be attributed to the weakening of the strong basal texture. PMID:28809252

Two-component end mills with multilayer composite nano-structured coatings as a viable alternative to monolithic carbide end mills

NASA Astrophysics Data System (ADS)

Vereschaka, Alexey; Mokritskii, Boris; Mokritskaya, Elena; Sharipov, Oleg; Oganyan, Maksim

2018-03-01

The paper deals with the challenges of the application of two-component end mills, which represent a combination of a carbide cutting part and a shank made of cheaper structural material. The calculations of strains and deformations of composite mills were carried out in comparison with solid carbide mills, with the use of the finite element method. The study also involved the comparative analysis of accuracy parameters of machining with monolithic mills and two-component mills with various shank materials. As a result of the conducted cutting tests in milling aluminum alloy with monolithic and two-component end mills with specially developed multilayer composite nano-structured coatings, it has been found that the use of such coatings can reduce strains and, correspondingly, deformations, which can improve the accuracy of machining. Thus, the application of two-component end mills with multilayer composite nano-structured coatings can provide a reduction in the cost of machining while maintaining or even improving the tool life and machining accuracy parameters.

On the role of particle cracking in flow and fracture of metal matrix composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brockenbrough, J.R.; Zok, F.W.

1995-01-01

The flow response of particle-reinforced metal matrix composites is studied using finite element methods. Unit cells containing either intact or cracked particles in a power law hardening matrix are used to determine the corresponding asymptotic flow strengths. The effects of the hardening exponent and the elastic mismatch between the particles and the matrix on the flow response are examined. For comparison, the flow response of power law hardening solids containing penny-shaped cracks is also evaluated. The latter results are found to be in reasonable agreement with those corresponding to composites that contain low volume fractions of cracked particles. The asymptoticmore » results are used to develop a one-dimensional constitutive law for composites which undergo progressive damage during tensile straining. This law is used to evaluate the strain at the onset of plastic instability. It is proposed that the instability strain be used as a measure of tensile ductility when the particle content is low and the particles are uniformly distributed through the matrix.« less

Fabrication of Nanosized Island-Like CdO Crystallites-Decorated TiO₂ Rod Nanocomposites via a Combinational Methodology and Their Low-Concentration NO₂ Gas-Sensing Behavior.

PubMed

Liang, Yuan-Chang; Xu, Nian-Cih; Wang, Chein-Chung; Wei, Da-Hua

2017-07-10

TiO₂-CdO composite rods were synthesized through a hydrothermal method and sputtering thin-film deposition. The hydrothermally derived TiO₂ rods exhibited a rectangular cross-sectional crystal feature with a smooth surface, and the as-synthesized CdO thin film exhibited a rounded granular surface feature. Structural analyses revealed that the CdO thin film sputtered onto the surfaces of the TiO₂ rods formed a discontinuous shell layer comprising many island-like CdO crystallites. The TiO₂-CdO composite rods were highly crystalline, and their surfaces were rugged. A comparison of the NO₂ gas-sensing properties of the CdO thin film, TiO₂ rods, and TiO₂-CdO composite rods revealed that the composite rods exhibited superior gas-sensing responses to NO₂ gas than did the CdO thin film and TiO 2 rods, which can be attributed to the microstructural differences and the formation of heterojunctions between the TiO₂ core and CdO crystallites.

Large-scale dark diversity estimates: new perspectives with combined methods.

PubMed

Ronk, Argo; de Bello, Francesco; Fibich, Pavel; Pärtel, Meelis

2016-09-01

Large-scale biodiversity studies can be more informative if observed diversity in a study site is accompanied by dark diversity, the set of absent although ecologically suitable species. Dark diversity methodology is still being developed and a comparison of different approaches is needed. We used plant data at two different scales (European and seven large regions) and compared dark diversity estimates from two mathematical methods: species co-occurrence (SCO) and species distribution modeling (SDM). We used plant distribution data from the Atlas Florae Europaeae (50 × 50 km grid cells) and seven different European regions (10 × 10 km grid cells). Dark diversity was estimated by SCO and SDM for both datasets. We examined the relationship between the dark diversity sizes (type II regression) and the overlap in species composition (overlap coefficient). We tested the overlap probability according to the hypergeometric distribution. We combined the estimates of the two methods to determine consensus dark diversity and composite dark diversity. We tested whether dark diversity and completeness of site diversity (log ratio of observed and dark diversity) are related to various natural and anthropogenic factors differently than simple observed diversity. Both methods provided similar dark diversity sizes and distribution patterns; dark diversity is greater in southern Europe. The regression line, however, deviated from a 1:1 relationship. The species composition overlap of two methods was about 75%, which is much greater than expected by chance. Both consensus and composite dark diversity estimates showed similar distribution patterns. Both dark diversity and completeness measures exhibit relationships to natural and anthropogenic factors different than those exhibited by observed richness. In summary, dark diversity revealed new biodiversity patterns which were not evident when only observed diversity was examined. A new perspective in dark diversity studies can incorporate a combination of methods.

Activation of Carbon-Hydrogen and Hydrogen-Hydrogen Bonds by Copper-Nitrenes: A Comparison of Density Functional Theory with Single- and Multireference Correlation Consistent Composite Approaches.

PubMed

Tekarli, Sammer M; Williams, T Gavin; Cundari, Thomas R

2009-11-10

The kinetics and thermodynamics of copper-mediated nitrene insertion into C-H and H-H bonds (the former of methane) have been studied using several levels of theory: B3LYP/6-311++G(d,p), B97-1/cc-pVTZ, PBE1KCIS/cc-pVTZ, and ccCA (correlation consistent Composite Approach). The results show no significant difference among the DFT methods. All three DFT methods predict the ground state of the copper-nitrene model complex, L'Cu(NH), to be a triplet, while single reference ccCA predicts the singlet to be the ground state. The contributions to the total ccCA energy indicate that the singlet state is favored at the MP2/CBS level of theory, while electron correlation beyond this level (CCSD(T)) favors a triplet state, resulting in a close energetic balance between the two states. A multireference ccCA method is applied to the nitrene active species and supports the assignment of a singlet ground state. In general, the largest difference in the model reaction cycles between DFT and ccCA methods is for processes involving radicals and bond dissociation.

A phylogenetic comparison of urease-positive thermophilic Campylobacter (UPTC) and urease-negative (UN) C. lari.

PubMed

Hirayama, Junichi; Tazumi, Akihiro; Hayashi, Kyohei; Tasaki, Erina; Kuribayashi, Takashi; Moore, John E; Millar, Beverley C; Matsuda, Motoo

2011-06-01

In the present study, the reliability of full-length gene sequence information for several genes including 16S rRNA was examined, for the discrimination of the two representative Campylobacter lari taxa, namely urease-negative (UN) C. lari and urease-positive thermophilic Campylobacter (UPTC). As previously described, 16S rRNA gene sequence are not reliable for the molecular discrimination of UN C. lari from UPTC organisms employing both the unweighted pair group method using arithmetic means analysis (UPGMA) and neighbor joining (NJ) methods. In addition, three composite full-length gene sequences (ciaB, flaC and vacJ) out of seven gene loci examined were reliable for discrimination employing dendrograms constructed by the UPGMA method. In addition, all the dendrograms of the NJ phylogenetic trees constructed based on the nine gene information were not reliable for the discrimination. Three composite full-length gene sequences (ciaB, flaC and vacJ) were reliable for the molecular discrimination between UN C. lari and UPTC organisms employing the UPGMA method, as well as among four thermophilic Campylobacter species. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of exergaming based exercise on urban children's physical activity participation and body composition.

PubMed

Gao, Zan; Xiang, Ping

2014-07-01

Exergaming has been considered a fun solution to promoting a physically active lifestyle. This study examined the impact of an exergaming-based program on urban children's physical activity participation, body composition and perceptions of the program. A sample of 185 children's physical activity was measured in August 2009 (pretest), and percent body fat was used as index of body composition. Fourth graders were assigned to intervention group engaging in 30 minutes exergaming-based activities 3 times per week, while third and fifth graders were in comparison group. Measurements were repeated 9 months later (posttest). Interviews were conducted among 12 intervention children. ANCOVA with repeated measures revealed a significant main effect for intervention, F(1, 179) = 10.69, P < .01. Specifically, intervention children had significantly greater increased physical activity levels than comparison children. Logistic regression for body composition indicated intervention children did not differ significantly in percent body fat change from comparison children, Chi square = 5.42, P = .14. Children interviewed reported positive attitudes toward the intervention. The implementation of exergaming-based program could have a significantly positive effect on children's physical activity participation and attitudes. Meanwhile, long-term effect of the program on children's body composition deserves further investigation.

Comparison of Reactive and Non-Reactive Spark Plasma Sintering Routes for the Fabrication of Monolithic and Composite Ultra High Temperature Ceramics (UHTC) Materials

PubMed Central

Orrù, Roberto; Cao, Giacomo

2013-01-01

A wider utilization of ultra high temperature ceramics (UHTC) materials strongly depends on the availability of efficient techniques for their fabrication as dense bodies. Based on recent results reported in the literature, it is possible to state that Spark Plasma Sintering (SPS) technology offers a useful contribution in this direction. Along these lines, the use of two different SPS-based processing routes for the preparation of massive UHTCs is examined in this work. One method, the so-called reactive SPS (R-SPS), consists of the synthesis and densification of the material in a single step. Alternatively, the ceramic powders are first synthesized by Self-propagating High-temperature Synthesis (SHS) and then sintered by SPS. The obtained results evidenced that R-SPS method is preferable for the preparation of dense monolithic products, while the sintering of SHS powders requires relatively milder conditions when considering binary composites. The different kinetic mechanisms involved during R-SPS of the monolithic and composite systems, i.e., combustion-like or gradual solid-diffusion, respectively, provides a possible explanation. An important role is also played by the SHS process, particularly for the preparation of composite powders, since stronger interfaces are established between the ceramic constituents formed in situ, thus favoring diffusion processes during the subsequent SPS step. PMID:28809229

Investigation on the parameter optimization and performance of laser cladding a gradient composite coating by a mixed powder of Co50 and Ni/WC on 20CrMnTi low carbon alloy steel

NASA Astrophysics Data System (ADS)

Shi, Yan; Li, Yunfeng; Liu, Jia; Yuan, Zhenyu

2018-02-01

In this study, a gradient composite coating was manufactured on 20CrMnTi alloy steel by laser cladding. The laser power, cladding scan velocity and powder flow rate were selected as influencing factors of the orthogonal cladding experiments. The influencing factors were optimized by the comprehensive analysis of Taguchi OA and TOPSIS method. The high significant parameters and the predicted results were confirmed by the ANOVA method. The macromorphology and microstructures are characterized by using laser microscope, SEM, XRD and microhardness tester. Comparison tests of wear resistance of gradient composite coating, 20CrMnTi cemented quenching sample and the 20CrMnTi sample were conducted on the friction-wear tester. The results show that the phases are γ-Co solid solution, Co3B, M23C6 and etc. The interlayers and wear-resisting layer also contain new hard phases as WC, W2C. The microhardness of the gradient coating was increased to 3 times as compared with that of the 20CrMnTi substrate. The wear resistance of the gradient composite coating and 20CrMnTi cemented quenching sample was enhanced to 36.4 and 15.9 times as compared with that of the 20CrMnTi.

Mechanical and wear characteristics of epoxy composites filled with industrial wastes: A comparative study

NASA Astrophysics Data System (ADS)

Purohit, A.; Satapathy, A.

2017-02-01

Use of industrial wastes, such as slag and sludge particles, as filler in polymers is not very common in the field of composite research. Therefore in this paper, a comparison of mechanical characteristics of epoxy based composites filled with LD sludge, BF slag and LD slag (wastes generated in iron and steel industries) were presented. A comparative study among these composites in regard to their dry sliding wear characteristics under similar test conditions was also included. Composites with different weight proportions (0, 5, 10, 15 and 20 wt.%) of LD sludge were fabricated by solution casting technique. Mechanical properties were evaluated as per ASTM test standards and sliding wear test was performed following a design of experiment approach based on Taguchi’s orthogonal array. The test results for epoxy-LD sludge composites were compared with those of epoxy-BF slag and epoxy-LD slag composites reported by previous investigators. The comparison reveals that epoxy filled with LD sludge exhibits superior mechanical and wear characteristics among the three types of composites considered in this study.

405 nm diode laser, halogen lamp and LED device comparison in dental composites cure: an "in vitro" experimental trial.

PubMed

Fornaini, C; Lagori, G; Merigo, E; Rocca, J-P; Chiusano, M; Cucinotta, A

2015-12-30

A 405 nm diode laser is indicated for composite materials polymerizing, thanks to the recent evolution in their compositions, absorbing in blue part of the spectrum. The purpose of this research was to evaluate its performance on two different kinds of composite resins. Two different composites were polymerized with a traditional halogen lamp, a LED device and a 405 nm diode laser. The depth of the cure, the volumetric shrinkage, and the degree of the conversion (DC%) of the double bond during the curing process were measured. One-way ANOVA test, Kruskal-Wallis tests, and Dunn comparison tests were used for statistic analysis. Regarding the depth of polymerization, the laser had the worst performance on one composite while on the other, no significant difference with the other devices was observed. The volumetric shrinkage showed that laser produced the lowest change in both of the composites. The DC% measure confirmed these findings. Based on the results of this preliminary study, it is not possible to recommend the 405 nm diode laser for the polymerization of dental composites.

Comparison of Standard Culture-Based Method to Culture-Independent Method for Evaluation of Hygiene Effects on the Hand Microbiome

PubMed Central

Leff, J.; Henley, J.; Tittl, J.; De Nardo, E.; Butler, M.; Griggs, R.; Fierer, N.

2017-01-01

ABSTRACT Hands play a critical role in the transmission of microbiota on one’s own body, between individuals, and on environmental surfaces. Effectively measuring the composition of the hand microbiome is important to hand hygiene science, which has implications for human health. Hand hygiene products are evaluated using standard culture-based methods, but standard test methods for culture-independent microbiome characterization are lacking. We sampled the hands of 50 participants using swab-based and glove-based methods prior to and following four hand hygiene treatments (using a nonantimicrobial hand wash, alcohol-based hand sanitizer [ABHS], a 70% ethanol solution, or tap water). We compared results among culture plate counts, 16S rRNA gene sequencing of DNA extracted directly from hands, and sequencing of DNA extracted from culture plates. Glove-based sampling yielded higher numbers of unique operational taxonomic units (OTUs) but had less diversity in bacterial community composition than swab-based sampling. We detected treatment-induced changes in diversity only by using swab-based samples (P < 0.001); we were unable to detect changes with glove-based samples. Bacterial cell counts significantly decreased with use of the ABHS (P < 0.05) and ethanol control (P < 0.05). Skin hydration at baseline correlated with bacterial abundances, bacterial community composition, pH, and redness across subjects. The importance of the method choice was substantial. These findings are important to ensure improvement of hand hygiene industry methods and for future hand microbiome studies. On the basis of our results and previously published studies, we propose recommendations for best practices in hand microbiome research. PMID:28351915

Development and Application of a Tool for Optimizing Composite Matrix Viscoplastic Material Parameters

NASA Technical Reports Server (NTRS)

Murthy, Pappu L. N.; Naghipour Ghezeljeh, Paria; Bednarcyk, Brett A.

2018-01-01

This document describes a recently developed analysis tool that enhances the resident capabilities of the Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) and its application. MAC/GMC is a composite material and laminate analysis software package developed at NASA Glenn Research Center. The primary focus of the current effort is to provide a graphical user interface (GUI) capability that helps users optimize highly nonlinear viscoplastic constitutive law parameters by fitting experimentally observed/measured stress-strain responses under various thermo-mechanical conditions for braided composites. The tool has been developed utilizing the MATrix LABoratory (MATLAB) (The Mathworks, Inc., Natick, MA) programming language. Illustrative examples shown are for a specific braided composite system wherein the matrix viscoplastic behavior is represented by a constitutive law described by seven parameters. The tool is general enough to fit any number of experimentally observed stress-strain responses of the material. The number of parameters to be optimized, as well as the importance given to each stress-strain response, are user choice. Three different optimization algorithms are included: (1) Optimization based on gradient method, (2) Genetic algorithm (GA) based optimization and (3) Particle Swarm Optimization (PSO). The user can mix and match the three algorithms. For example, one can start optimization with either 2 or 3 and then use the optimized solution to further fine tune with approach 1. The secondary focus of this paper is to demonstrate the application of this tool to optimize/calibrate parameters for a nonlinear viscoplastic matrix to predict stress-strain curves (for constituent and composite levels) at different rates, temperatures and/or loading conditions utilizing the Generalized Method of Cells. After preliminary validation of the tool through comparison with experimental results, a detailed virtual parametric study is presented wherein the combined effects of temperature and loading rate on the predicted response of a braided composite is investigated.

Resin transfer molding of textile preforms for aircraft structural applications

NASA Technical Reports Server (NTRS)

Hasko, Gregory H.; Dexter, H. Benson; Weideman, Mark H.

1992-01-01

The NASA LaRC is conducting and supporting research to develop cost-effective fabrication methods that are applicable to primary composite aircraft structures. One of the most promising fabrication methods that has evolved is resin transfer molding (RTM) of dry textile material forms. RTM has been used for many years for secondary structures, but has received increased emphasis because it is an excellent method for applying resin to damage-tolerant textile preforms at low cost. Textile preforms based on processes such as weaving, braiding, knitting, stitching, and combinations of these have been shown to offer significant improvements in damage tolerance compared to laminated tape composites. The use of low-cost resins combined with textile preforms could provide a major breakthrough in achieving cost-effective composite aircraft structures. RTM uses resin in its lowest cost form, and storage and spoilage costs are minimal. Near net shape textile preforms are expected to be cost-effective because automated machines can be used to produce the preforms, post-cure operations such as machining and fastening are minimized, and material scrap rate may be reduced in comparison with traditional prepreg molding. The purpose of this paper is to discuss experimental and analytical techniques that are under development at NASA Langley to aid the engineer in developing RTM processes for airframe structural elements. Included are experimental techniques to characterize preform and resin behavior and analytical methods that were developed to predict resin flow and cure kinetics.

Genomic Data Quality Impacts Automated Detection of Lateral Gene Transfer in Fungi

PubMed Central

Dupont, Pierre-Yves; Cox, Murray P.

2017-01-01

Lateral gene transfer (LGT, also known as horizontal gene transfer), an atypical mechanism of transferring genes between species, has almost become the default explanation for genes that display an unexpected composition or phylogeny. Numerous methods of detecting LGT events all rely on two fundamental strategies: primary structure composition or gene tree/species tree comparisons. Discouragingly, the results of these different approaches rarely coincide. With the wealth of genome data now available, detection of laterally transferred genes is increasingly being attempted in large uncurated eukaryotic datasets. However, detection methods depend greatly on the quality of the underlying genomic data, which are typically complex for eukaryotes. Furthermore, given the automated nature of genomic data collection, it is typically impractical to manually verify all protein or gene models, orthology predictions, and multiple sequence alignments, requiring researchers to accept a substantial margin of error in their datasets. Using a test case comprising plant-associated genomes across the fungal kingdom, this study reveals that composition- and phylogeny-based methods have little statistical power to detect laterally transferred genes. In particular, phylogenetic methods reveal extreme levels of topological variation in fungal gene trees, the vast majority of which show departures from the canonical species tree. Therefore, it is inherently challenging to detect LGT events in typical eukaryotic genomes. This finding is in striking contrast to the large number of claims for laterally transferred genes in eukaryotic species that routinely appear in the literature, and questions how many of these proposed examples are statistically well supported. PMID:28235827

Loop system for creating jet fuel vapor standards used in the calibration of infrared spectrophotometers and gas chromatographs.

PubMed

Reboulet, James; Cunningham, Robert; Gunasekar, Palur G; Chapman, Gail D; Stevens, Sean C

2009-02-01

A whole body inhalation study of mixed jet fuel vapor and its aerosol necessitated the development of a method for preparing vapor only standards from the neat fuel. Jet fuel is a complex mixture of components which partitions between aerosol and vapor when aspirated based on relative volatility of the individual compounds. A method was desired which could separate the vapor portion from the aerosol component to prepare standards for the calibration of infrared spectrophotometers and a head space gas chromatography system. A re-circulating loop system was developed which provided vapor only standards whose composition matched those seen in an exposure system. Comparisons of nominal concentrations in the exposure system to those determined by infrared spectrophotometry were in 92-95% agreement. Comparison of jet fuel vapor concentrations determined by infrared spectrophotometry compared to head space gas chromatography yielded a 93% overall agreement in trial runs. These levels of agreement show the loop system to be a viable method for creating jet fuel vapor standards for calibrating instruments.

Comparison of Uriswab to alternative methods for urine culture collection and transport: confirmation of standard culture methodology for investigation of urinary tract infections.

PubMed

Rennie, Robert P; Turnbull, Lee-Ann; Gauchier-Pitts, Kaylee; Bennett, Tracy; Dyrland, Debbie; Blonski, Susan

2016-08-01

The ability to isolate and identify causative agents of urinary tract infections relies primarily on the quality of the urine sample that is submitted to the microbiology. The most important factors are the method of collection, the maintenance of viability of the potential pathogens during transport, and standardization of the culturing of the urine sample. This report is a composite of several investigations comparing collection and transport on urine culture paddles, with a preservative urine sponge (Uriswab), and a comparison of Uriswab with the BD preservative transport tube as methods of preservation of urinary pathogens. Primary studies showed that Uriswab maintained significantly more urinary pathogens than the urine culture paddle with fewer mixed or contaminated cultures. The two preservative transport systems were comparable for maintenance of viability of the pathogens, but there were fewer mixed cultures when samples were collected with Uriswab. This study confirms the importance of a standard volume of 1 μL of urine for culture. Copyright © 2016 Elsevier Inc. All rights reserved.

A new method of metallization for silicon solar cells

NASA Technical Reports Server (NTRS)

Macha, M.

1979-01-01

The new metallization process based on Mo-Sn system was studied. The reaction mechanism of MoO3 and its mixture with Sn was examined. The basic ink composition was modified in order to obtain a low ohmic contact to the cell. The electrical characteristics of the cells were comparable with the existing metallization processes. However, in comparison with the standard processes using silver as the contacting metal, the saving obtained by the use of the new process was substantial.

Ultrathin fiber poly-3-hydroxybutyrate, modified by silicon carbide nanoparticles

NASA Astrophysics Data System (ADS)

Olkhov, A. A.; Krutikova, A. A.; Goldshtrakh, M. A.; Staroverova, O. V.; Iordanskii, A. L.; Ischenko, A. A.

2016-11-01

The article presents the results of studies the composite fibrous material based on poly-3-hydroxybutyrate (PHB) and nano-size silicon carbide obtained by the electrospinning method. Size distribution of the silicon carbide nanoparticles in the fiber was estimated by X-ray diffraction technique. It is shown that immobilization of the SiC nanoparticles to the PHB fibers contributes to obtaining essentially smaller diameter of fibers, high physical-mechanical characteristics and increasing resistance to degradation in comparison with the fibers of PHB.

On the Finite Element Implementation of the Generalized Method of Cells Micromechanics Constitutive Model

NASA Technical Reports Server (NTRS)

Wilt, T. E.

1995-01-01

The Generalized Method of Cells (GMC), a micromechanics based constitutive model, is implemented into the finite element code MARC using the user subroutine HYPELA. Comparisons in terms of transverse deformation response, micro stress and strain distributions, and required CPU time are presented for GMC and finite element models of fiber/matrix unit cell. GMC is shown to provide comparable predictions of the composite behavior and requires significantly less CPU time as compared to a finite element analysis of the unit cell. Details as to the organization of the HYPELA code are provided with the actual HYPELA code included in the appendix.

An experimental and analytical investigation on the response of GR/EP composite I-frames

NASA Technical Reports Server (NTRS)

Moas, E., Jr.; Boitnott, R. L.; Griffin, O. H., Jr.

1991-01-01

Six-foot diameter, semicircular graphite/epoxy specimens representative of generic aircraft frames were loaded quasi-statically to determine their load response and failure mechanisms for large deflections that occur in an airplane crash. These frame-skin specimens consisted of a cylindrical skin section cocured with a semicircular I-frame. Various frame laminate stacking sequences and geometries were evaluated by statically loading the specimen until multiple failures occurred. Two analytical methods were compared for modeling the frame-skin specimens: a two-dimensional branched-shell finite element analysis and a one-dimensional, closed-form, curved beam solution derived using an energy method. Excellent correlation was obtained between experimental results and the finite element predictions of the linear response of the frames prior to the initial failure. The beam solution was used for rapid parameter and design studies, and was found to be stiff in comparison with the finite element analysis. The specimens were found to be useful for evaluating composite frame designs.

Analysis of airborne MAIS imaging spectrometric data for mineral exploration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Jinnian; Zheng Lanfen; Tong Qingxi

1996-11-01

The high spectral resolution imaging spectrometric system made quantitative analysis and mapping of surface composition possible. The key issue will be the quantitative approach for analysis of surface parameters for imaging spectrometer data. This paper describes the methods and the stages of quantitative analysis. (1) Extracting surface reflectance from imaging spectrometer image. Lab. and inflight field measurements are conducted for calibration of imaging spectrometer data, and the atmospheric correction has also been used to obtain ground reflectance by using empirical line method and radiation transfer modeling. (2) Determining quantitative relationship between absorption band parameters from the imaging spectrometer data andmore » chemical composition of minerals. (3) Spectral comparison between the spectra of spectral library and the spectra derived from the imagery. The wavelet analysis-based spectrum-matching techniques for quantitative analysis of imaging spectrometer data has beer, developed. Airborne MAIS imaging spectrometer data were used for analysis and the analysis results have been applied to the mineral and petroleum exploration in Tarim Basin area china. 8 refs., 8 figs.« less

Optimal design of geodesically stiffened composite cylindrical shells

NASA Technical Reports Server (NTRS)

Gendron, G.; Guerdal, Z.

1992-01-01

An optimization system based on the finite element code Computations Structural Mechanics (CSM) Testbed and the optimization program, Automated Design Synthesis (ADS), is described. The optimization system can be used to obtain minimum-weight designs of composite stiffened structures. Ply thickness, ply orientations, and stiffener heights can be used as design variables. Buckling, displacement, and material failure constraints can be imposed on the design. The system is used to conduct a design study of geodesically stiffened shells. For comparison purposes, optimal designs of unstiffened shells and shells stiffened by rings and stingers are also obtained. Trends in the design of geodesically stiffened shells are identified. An approach to include local stress concentrations during the design optimization process is then presented. The method is based on a global/local analysis technique. It employs spline interpolation functions to determine displacements and rotations from a global model which are used as 'boundary conditions' for the local model. The organization of the strategy in the context of an optimization process is described. The method is validated with an example.

Characterisation of chamomile volatiles by simultaneous distillation solid-phase extraction in comparison to hydrodistillation and simultaneous distillation extraction.

PubMed

Krüger, Hans

2010-05-01

A new method for complete separation of steam-volatile organic compounds is described using the example of chamomile flowers. This method is based on the direct combination of hydrodistillation and solid-phase extraction in a circulation apparatus. In contrast to hydrodistillation and simultaneous distillation extraction (SDE), an RP-18 solid phase as adsorptive material is used rather than a water-insoluble solvent. Therefore, a prompt and complete fixation of all volatiles takes place, and the circulation of water-soluble bisabololoxides as well as water-soluble and thermolabile en-yne-spiroethers is inhibited. This so-called simultaneous distillation solid-phase extraction (SD-SPE) provides extracts that better characterise the real composition of the vapour phase, as well as the composition of inhalation vapours, than do SDE extracts or essential oils obtained by hydrodistillation. The data indicate that during inhalation therapy with chamomile, the bisabololoxides and spiroethers are more strongly involved in the inhaling activity than so far assumed. Georg Thieme Verlag KG Stuttgart New York.

Refined composite multivariate generalized multiscale fuzzy entropy: A tool for complexity analysis of multichannel signals

NASA Astrophysics Data System (ADS)

Azami, Hamed; Escudero, Javier

2017-01-01

Multiscale entropy (MSE) is an appealing tool to characterize the complexity of time series over multiple temporal scales. Recent developments in the field have tried to extend the MSE technique in different ways. Building on these trends, we propose the so-called refined composite multivariate multiscale fuzzy entropy (RCmvMFE) whose coarse-graining step uses variance (RCmvMFEσ2) or mean (RCmvMFEμ). We investigate the behavior of these multivariate methods on multichannel white Gaussian and 1/ f noise signals, and two publicly available biomedical recordings. Our simulations demonstrate that RCmvMFEσ2 and RCmvMFEμ lead to more stable results and are less sensitive to the signals' length in comparison with the other existing multivariate multiscale entropy-based methods. The classification results also show that using both the variance and mean in the coarse-graining step offers complexity profiles with complementary information for biomedical signal analysis. We also made freely available all the Matlab codes used in this paper.

Pressurized liquid extraction and chemical characterization of safflower oil: A comparison between methods.

PubMed

Conte, Rogério; Gullich, Letícia M D; Bilibio, Denise; Zanella, Odivan; Bender, João P; Carniel, Naira; Priamo, Wagner L

2016-12-15

This work investigates the extraction process of safflower oil using pressurized ethanol, and compares the chemical composition obtained (in terms of fatty acids) with other extraction techniques. Soxhlet and Ultrasound showed maximum global yield of 36.53% and 30.41%, respectively (70°C and 240min). PLE presented maximum global yields of 25.62% (3mLmin(-1)), 19.94% (2mLmin(-1)) and 12.37% (1mLmin(-1)) at 40°C, 100bar and 60min. Palmitic acid showed the lower concentration in all experimental conditions (from 5.70% to 7.17%); Stearic and Linoleic acid presented intermediate concentrations (from 2.93% to 25.09% and 14.09% to 19.06%, respectively); Oleic acid showed higher composition (from 55.12% to 83.26%). Differences between percentages of fatty acids, depending on method were observed. Results may be applied to maximize global yields and select fatty acids, reducing the energetic costs and process time. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations.

PubMed

Alizadeh Oskoee, Parnian; Pournaghi Azar, Fatemeh; Jafari Navimipour, Elmira; Ebrahimi Chaharom, Mohammad Esmaeel; Naser Alavi, Fereshteh; Salari, Ashkan

2017-01-01

Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90]) and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C). Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P < 0.05. Results. The maximum and minimum gaps were detected in groups 1-A and 2-B, respectively. The effects of composite resin type, preheating and interactive effect of these variables on gap formation were significant (P<0.001). Post-hoc Tukey tests showed greater gap in dimethacrylate compared to silorane composite resins (P< 0.001). In each group, gap values were greater in composite resins at room temperature compared to composite resins after 40 preheating cycles (P<0.001). Conclusion. Gap formation at the gingival margins of Class V cavities decreased due to preheating of both composite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation.

The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations

PubMed Central

Alizadeh Oskoee, Parnian; Pournaghi Azar, Fatemeh; Jafari Navimipour, Elmira; Ebrahimi chaharom, Mohammad Esmaeel; Naser Alavi, Fereshteh; Salari, Ashkan

2017-01-01

Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90]) and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C). Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P < 0.05. Results. The maximum and minimum gaps were detected in groups 1-A and 2-B, respectively. The effects of composite resin type, preheating and interactive effect of these variables on gap formation were significant (P<0.001). Post-hoc Tukey tests showed greater gap in dimethacrylate compared to silorane composite resins (P< 0.001). In each group, gap values were greater in composite resins at room temperature compared to composite resins after 40 preheating cycles (P<0.001). Conclusion. Gap formation at the gingival margins of Class V cavities decreased due to preheating of both composite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation. PMID:28413594

Facile Synthesis of Efficient Antibacterial Agent as CoFe₂O₄/Ag Composite Material Against Both Gram-Negative Escherichia coli and Gram-Positive Bacillus subtilis Bacteria.

PubMed

Gankhuyag, Sukhbayar; Lee, Kyoung; Bae, Dong Sik

2018-09-01

We have suggested that a facile synthesis of CoFe2O4/Ag composite material as an antibacterial agent for substitution of a chlorination agent for microbial infected wastewater treatment. The CoFe2O4/Ag was synthesized by an impregnation method in assistance with trisodium citrate as a reducing agent. The as-prepared uncalcined CoFe2O4 (CFG), calcined CoFe2O4 (CFG600), and calcined CoFe2O4/Ag (CFG600/Ag) composites were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray (EDX) techniques. Antibacterial activities were also determined in liquid culture by measuring the minimum inhibitory concentrations (MIC) against Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) bacteria in vitro. Results showed that CFG600/Ag composites had an excellent antibacterial activity in comparison with CFG and CFG600 composites. The CFG600/Ag composites have completely inhibited the growth of both E. coli and B. subtilis bacteria from concentrations of more than 0.25 mg/ml. Furthermore, the FE-SEM study demonstrated the physical damage of bacteria when treated with CFG600/Ag composite material at a concentration of 0.10 mg/ml.

Human Milk Fatty Acid Composition: Comparison of Novel Dried Milk Spot Versus Standard Liquid Extraction Methods.

PubMed

Rudolph, Michael C; Young, Bridget E; Jackson, Kristina Harris; Krebs, Nancy F; Harris, William S; MacLean, Paul S

2016-12-01

Accurate assessment of the long chain polyunsaturated fatty acid (LC-PUFA) content of human milk (HM) provides a powerful means to evaluate the FA nutrient status of breastfed infants. The conventional standard for FA composition analysis of HM is liquid extraction, trans-methylation, and analyte detection resolved by gas chromatography. This standard approach requires fresh or frozen samples, storage in deep freeze, organic solvents, and specialized equipment in processing and analysis. Further, HM collection is often impractical for many studies in the free living environment, particularly for studies in developing countries. In the present study, we compare a novel and more practical approach to sample collection and processing that involves the spotting and drying ~50 μL of HM on a specialized paper stored and transported at ambient temperatures until analysis. Deming regression indicated the two methods aligned very well for all LC-PUFA and the abundant HM FA. Additionally, strong correlations (r > 0.85) were observed for DHA, ARA, EPA, linoleic (LA), and alpha-linolenic acids (ALA), which are of particular interest to the health of the developing infant. Taken together, our data suggest this more practical and inexpensive method of collection, storage, and transport of HM milk samples could dramatically facilitate studies of HM, as well as understanding its lipid composition influences on human health and development.

Comparison of Single-Phase and Two-Phase Composite Thermal Barrier Coatings with Equal Total Rare-Earth Content

NASA Astrophysics Data System (ADS)

Rai, Amarendra K.; Schmitt, Michael P.; Dorfman, Mitchell R.; Zhu, Dongming; Wolfe, Douglas E.

2018-04-01

Rare-earth zirconates have been the focus of advanced thermal barrier coating research for nearly two decades; however, their lack of toughness prevents a wide-scale adoption due to lack of erosion and thermal cyclic durability. There are generally two methods of improving toughness: intrinsic modification of the coating chemistry and extrinsic modification of the coating structure. This study compares the efficacy of these two methods for a similar overall rare-earth content via the air plasma spray process. The extrinsically toughened coatings were comprised of a two-phase composite containing 30 wt.% Gd2Zr2O7 (GZO) combined with 70 wt.% of a tougher t' low-k material (ZrO2-2Y2O3-1Gd2O3-1Yb2O3; mol.%), while a single-phase fluorite with the overall rare-earth content equivalent to the two-phase composite (13 mol.% rare-earth) was utilized to explore intrinsically toughened concept. The coatings were then characterized via x-ray diffraction, energy-dispersive spectroscopy, and scanning electron microscopy, and their performance was evaluated via erosion, thermal conductivity, thermal annealing (500 h), and thermal cycling. It was shown that the extrinsic method provided an improved erosion and thermal conductivity response over the single phase, but at the expense of high-temperature stability and cyclic life.

Influence of stage of lactation and year season on composition of mares' colostrum and milk and method and time of storage on vitamin C content in mares' milk.

PubMed

Markiewicz-Kęszycka, Maria; Czyżak-Runowska, Grażyna; Wójtowski, Jacek; Jóźwik, Artur; Pankiewicz, Radosław; Łęska, Bogusława; Krzyżewski, Józef; Strzałkowska, Nina; Marchewka, Joanna; Bagnicka, Emilia

2015-08-30

Mares' milk is becoming increasingly popular in Western Europe. This study was thus aimed at investigating the impact of stage of lactation and season on chemical composition, somatic cell count and some physicochemical parameters of mares' colostrum and milk, and at developing a method for the determination of vitamin C (ascorbic acid) in mares' milk and to determine its content in fresh and stored milk. The analysis conducted showed an effect of the stage of lactation on contents of selected chemical components and physicochemical parameters of mares' milk. In successive lactation periods levels of fat, cholesterol, energy value, citric acid and titratable acidity decreased, whereas levels of lactose and vitamin C, as well as the freezing point, increased. Analysis showed that milk produced in autumn (September, October, November) had a higher freezing point and lower concentrations of total solids, protein, fat, cholesterol, citric acid and energy value in comparison to milk produced in summer (June, July, August). Mares' milk was characterised by low somatic cell count throughout lactation. In terms of vitamin C stability the most advantageous method of milk storage was 6-month storage of lyophilised milk. In general, the results confirmed that mares' milk is a raw material with a unique chemical composition different from that produced by other farm animals. © 2014 Society of Chemical Industry.

Comparison of Metabolomics Approaches for Evaluating the Variability of Complex Botanical Preparations: Green Tea (Camellia sinensis) as a Case Study.

PubMed

Kellogg, Joshua J; Graf, Tyler N; Paine, Mary F; McCune, Jeannine S; Kvalheim, Olav M; Oberlies, Nicholas H; Cech, Nadja B

2017-05-26

A challenge that must be addressed when conducting studies with complex natural products is how to evaluate their complexity and variability. Traditional methods of quantifying a single or a small range of metabolites may not capture the full chemical complexity of multiple samples. Different metabolomics approaches were evaluated to discern how they facilitated comparison of the chemical composition of commercial green tea [Camellia sinensis (L.) Kuntze] products, with the goal of capturing the variability of commercially used products and selecting representative products for in vitro or clinical evaluation. Three metabolomic-related methods-untargeted ultraperformance liquid chromatography-mass spectrometry (UPLC-MS), targeted UPLC-MS, and untargeted, quantitative 1 HNMR-were employed to characterize 34 commercially available green tea samples. Of these methods, untargeted UPLC-MS was most effective at discriminating between green tea, green tea supplement, and non-green-tea products. A method using reproduced correlation coefficients calculated from principal component analysis models was developed to quantitatively compare differences among samples. The obtained results demonstrated the utility of metabolomics employing UPLC-MS data for evaluating similarities and differences between complex botanical products.

SU-E-T-101: Determination and Comparison of Correction Factors Obtained for TLDs in Small Field Lung Heterogenous Phantom Using Acuros XB and EGSnrc

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soh, R; Lee, J; Harianto, F

Purpose: To determine and compare the correction factors obtained for TLDs in 2 × 2cm{sup 2} small field in lung heterogenous phantom using Acuros XB (AXB) and EGSnrc. Methods: This study will simulate the correction factors due to the perturbation of TLD-100 chips (Harshaw/Thermoscientific, 3 × 3 × 0.9mm{sup 3}, 2.64g/cm{sup 3}) in small field lung medium for Stereotactic Body Radiation Therapy (SBRT). A physical lung phantom was simulated by a 14cm thick composite cork phantom (0.27g/cm{sup 3}, HU:-743 ± 11) sandwiched between 4cm thick Plastic Water (CIRS,Norfolk). Composite cork has been shown to be a good lung substitute materialmore » for dosimetric studies. 6MV photon beam from Varian Clinac iX (Varian Medical Systems, Palo Alto, CA) with field size 2 × 2cm{sup 2} was simulated. Depth dose profiles were obtained from the Eclipse treatment planning system Acuros XB (AXB) and independently from DOSxyznrc, EGSnrc. Correction factors was calculated by the ratio of unperturbed to perturbed dose. Since AXB has limitations in simulating actual material compositions, EGSnrc will also simulate the AXB-based material composition for comparison to the actual lung phantom. Results: TLD-100, with its finite size and relatively high density, causes significant perturbation in 2 × 2cm{sup 2} small field in a low lung density phantom. Correction factors calculated by both EGSnrc and AXB was found to be as low as 0.9. It is expected that the correction factor obtained by EGSnrc wlll be more accurate as it is able to simulate the actual phantom material compositions. AXB have a limited material library, therefore it only approximates the composition of TLD, Composite cork and Plastic water, contributing to uncertainties in TLD correction factors. Conclusion: It is expected that the correction factors obtained by EGSnrc will be more accurate. Studies will be done to investigate the correction factors for higher energies where perturbation may be more pronounced.« less

IMPROVED CATALYSTS FOR HEAVY OIL UPGRADING BASED ON ZEOLITE Y NANOPARTICLES ENCAPSULATED IN STABLE NANOPOROUS HOST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conrad Ingram; Mark Mitchell

2005-11-15

Composite materials of SBA-15/zeolite Y were synthesized from zeolite Y precursor and a synthesis mixture of mesoporous silicate SBA-15 via a hydrothermal process in the presence of a slightly acidic media of pH 4-6 with 2M H{sub 2}SO{sub 4}. The SBA-15/ZY composites showed Type IV adsorption isotherms, narrow BJH average pore size distribution of 4.9 nm, surface areas up to 800 m{sup 2}2/g and pore volumes 1.03 cm{sup 3}, all comparable to pure SBA-15 synthesized under similar conditions. Chemical analysis revealed Si/Al ratio down to 8.5 in the most aluminated sample, and {sup 27}AlSS MAS NMR confirmed aluminum was inmore » tetrahedral coordination. This method of introduction of Al in pure T{sub d} coordination is effective in comparison to other direct and post synthesis alumination methods. Bronsted acid sites were evident from a pyridinium peak at 1544 cm-1 in the FTIR spectrum after pyridine adsorption, and from NH{sub 3} -TPD experiments. SBA-15/ZY composites showed significant catalytic activities for the dealkylation of isopropylbenzene to benzene and propene, similar to those of commercial zeolite Y. It was observed that higher conversion for catalysts synthesized with high amount of ZY precursor mixture added to the SBA-15. Over all the composites has shown good catalytic activity. Further studies will be focused on gaining a better understand the nature of the precursor, and to characterize and to locate the acid sites in the composite material. The composite will also be evaluated for heavy oil conversion to naphtha and middle distillates.« less

Multivariate Phylogenetic Comparative Methods: Evaluations, Comparisons, and Recommendations.

PubMed

Adams, Dean C; Collyer, Michael L

2018-01-01

Recent years have seen increased interest in phylogenetic comparative analyses of multivariate data sets, but to date the varied proposed approaches have not been extensively examined. Here we review the mathematical properties required of any multivariate method, and specifically evaluate existing multivariate phylogenetic comparative methods in this context. Phylogenetic comparative methods based on the full multivariate likelihood are robust to levels of covariation among trait dimensions and are insensitive to the orientation of the data set, but display increasing model misspecification as the number of trait dimensions increases. This is because the expected evolutionary covariance matrix (V) used in the likelihood calculations becomes more ill-conditioned as trait dimensionality increases, and as evolutionary models become more complex. Thus, these approaches are only appropriate for data sets with few traits and many species. Methods that summarize patterns across trait dimensions treated separately (e.g., SURFACE) incorrectly assume independence among trait dimensions, resulting in nearly a 100% model misspecification rate. Methods using pairwise composite likelihood are highly sensitive to levels of trait covariation, the orientation of the data set, and the number of trait dimensions. The consequences of these debilitating deficiencies are that a user can arrive at differing statistical conclusions, and therefore biological inferences, simply from a dataspace rotation, like principal component analysis. By contrast, algebraic generalizations of the standard phylogenetic comparative toolkit that use the trace of covariance matrices are insensitive to levels of trait covariation, the number of trait dimensions, and the orientation of the data set. Further, when appropriate permutation tests are used, these approaches display acceptable Type I error and statistical power. We conclude that methods summarizing information across trait dimensions, as well as pairwise composite likelihood methods should be avoided, whereas algebraic generalizations of the phylogenetic comparative toolkit provide a useful means of assessing macroevolutionary patterns in multivariate data. Finally, we discuss areas in which multivariate phylogenetic comparative methods are still in need of future development; namely highly multivariate Ornstein-Uhlenbeck models and approaches for multivariate evolutionary model comparisons. © The Author(s) 2017. Published by Oxford University Press on behalf of the Systematic Biology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effect of Different In Vitro Aging Methods on Color Stability of a Dental Resin-Based Composite Using CIELAB and CIEDE2000 Color-Difference Formulas.

PubMed

de Oliveira, Dayane Carvalho Ramos Salles; Ayres, Ana Paula Almeida; Rocha, Mateus Garcia; Giannini, Marcelo; Puppin Rontani, Regina Maria; Ferracane, Jack L; Sinhoreti, Mario Alexandre Coelho

2015-01-01

To evaluate the effect of different in vitro aging methods on color change (CC) of an experimental dental resin-based composite using CIELAB (ΔEab ) and CIEDE2000 (ΔE00 ) color-difference formulas. The CC was evaluated with a spectrophotometer (CM700d, Konica Minolta, Tokyo, Japan) according to the CIE chromatic space. Disk-shaped specimens (Φ = 5 × 1 mm thick) (N = 10) were submitted to different in vitro aging methods: 30 days of water aging (WA); 120 hours of ultraviolet light aging (UVA); or 300 hours of an accelerated artificial aging (AAA) method with cycles of 4 hours of UV-B light exposure and 4 hours of moisture condensation to induce CC. The temperature was standardized at 37°C for all aging methods. CC was evaluated with ΔEab and ΔE00 formulas. Differences in individual Lab coordinates were also calculated. Data for the individual color parameters were submitted to one-way analysis of variance and Tukey's test for multiple comparisons (α = 0.05). All in vitro aging methods tested induced CC, in the following order: WA: ΔEab = 0.83 (0.1); ΔE00  = 1.15 (0.1) < AAA: ΔEab  = 5.64 (0.2); ΔE00  = 5.01 (0.1) < UVA: ΔEab  = 6.74 (0.2); ΔE00  = 6.03 (0.4). No changes in L* or a* coordinates were ≥1; the methods with UV aging showed a yellowing effect due a large positive change in b*. All in vitro aging methods tested induced a CC, but to different extents. Changes in color followed similar trends, but with different absolute values when calculated with the CIELAB and the CIEDE2000 formulas. Establishing the efficacy of different artificial aging methods and differences between color change using CIELAB and CIEDE2000 formulas are important to standardize color stability evaluations and facilitate the comparison of outcomes from different studies in the literature. © 2015 Wiley Periodicals, Inc.

Effect of Laser-assisted and Conventional In-office Bleaching on Monomer Release from Microhybrid and Nanohybrid Composite.

PubMed

Omrani, Ladan Ranjbar; Farjadfar, Shayan; Pedram, Parham; Sadray, Sima; Kamangar, Sedighe Sadat Hashemi; Chiniforoush, Nasim

2017-06-30

Bleaching might affect structural properties of composite materials, and lead to monomer release. This study aimed to evaluate the effect of Laser-assisted and conventional in-office bleaching on the release of BIS-GMA, TEGDMA, and UDMA monomers from a nanohybrid and a microhybrid BIS-GMA based composite. 32 samples of each composite, were divided into 4 subgroups; subgroup 1: Conventional in-office bleaching (CIB) with the Opalescence Boost PF 38% gel, subgroup 2: Laser-assisted bleaching (LBO) with the Opalescence Boost PF 38% gel, subgroup 3: Laser-assisted bleaching (LBH) with the JW Power bleaching gel, subgroup 4: (CO) control without bleaching. All the samples were immersed in tubes of 2cc Ethanol 75% medium. The released monomers were analyzed using the high performance liquid chromatography (HPLC) method 24 h, 7, and 28 days. Data's were analyzed by Univariate Analysis of Variance test followed by Tukeys HSD. The amount of TEGDMA monomer released was not significant. However, nanohybrid composites showed significantly more monomer release than microhybrid composites (P < 0.05). For UDMA the interaction was significant only after 1 week. In microhybrid composites, the CO subgroup showed more monomer release than LBH and LBO. In nanohybrid composites, LBH showed more monomer release than CIB and CO subgroups. For BIS-GMA monomers the interaction was significant at all time periods and the LBH subgroup of nanohybrid composite had significantly more BIS_GMA release in comparison to other subgroups. Bleaching by laser with JW Power Bleaching gel led to more monomer release in nanohybrid composite.

Effects of water-aging on self-healing dental composite containing microcapsules

PubMed Central

Wu, Junling; Weir, Michael D.; Melo, Mary Anne S.; Strassler, Howard E.; Xu, Hockin H. K.

2016-01-01

Objectives The objectives of this study were to develop a self-healing dental composite containing poly(urea-formaldehyde) (PUF) shells with triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT) as healing liquid, and to investigate the mechanical properties of the composite and its self-healing efficacy after water-aging for 6 months. Methods PUF microspheres were synthesized encapsulating a TEGDMA-DHEPT healing liquid. Composite containing 30% of a resin matrix and 70% of glass fillers by mass was incorporated with 0%, 2.5%, 5%, 7.5% and 10% of microcapsules. A flexural test was used to measure flexural strength and elastic modulus. A single edge V-notched beam method was used to measure fracture toughness (KIC) and self-healing efficacy. Specimens were water-aged at 37 °C for 1 d to 6 months and then tested for self-healing. Fractured specimens were healed while being immersed in water to examine self-healing efficacy, in comparison with that in air. Results Incorporation of up to 7.5% of microcapsules into the resin composite achieved effective self-healing, without adverse effects on the virgin mechanical properties of the composite (p > 0.1). An excellent self-healing efficacy of 64%–77% recovery was obtained (mean ± sd; n = 6). Six months of water-aging did not decrease the self-healing efficacy compared to 1 d (p > 0.1). Exposure to water did not decrease the healing efficacy, compared to that healed in air (p > 0.1). Conclusions A composite was developed with excellent self-healing efficacy even while being immersed in water. The self-healing efficacy did not decrease with increasing water-aging time for 6 months. Clinical significance The novel self-healing composite may be promising for dental applications to heal cracks, resist fracture, and increase the durability and longevity. PMID:26808158

N-15 NMR Spectroscopy as a Method for Comparing the Rates of Imidization of Several Diamines

NASA Technical Reports Server (NTRS)

Johnson, J. Christopher; Kuczmarski, Maria A.

2006-01-01

The relative rates of the conversion of amide-acid to imide was measured for a series or aromatic diamines that have been identified as potential replacements for 4,4'-methylene dianiline (MDA) in high-temperature polyimides and polymer composites. These rates were compared with the N-15 NMR resonances of the unreacted amines. The initial rates of imidization track with the difference in chemical shift between the amine nitrogens in MDA and those in the subject diamines. This comparison demonstrated that N-15 NMR spectroscopy is appropriate for the rapid screening of candidate diamines to determine their reactivity relative to MDA, and can serve to provide guidance to the process of creating the time-temperature profiles used in processing these materials into polymer matrix composites.

The thermo-optical behavior of turbid composite laminates under highly energetic laser irradiations

NASA Astrophysics Data System (ADS)

Allheily, Vadim; Merlat, Lionel; Lacroix, Fabrice; Eichhorn, Alfred; L'Hostis, Gildas

2017-01-01

From their prior emergence in the military domain but also nowadays in the civilian area, unmanned air vehicles constitute a growing threat to the todays civilization. In this respect, novel laser weapons are considered to eradicate this menace and the vulnerability of typical aeronautic materials under 1.07μm-wavelength irradiations is also investigated. In this paper, Kubelka-Munk optical parameters of laminated glass fiber-reinforced plastic composites are first assessed to build up a basic analytical interaction model involving internal refraction and reflection as well as the scattering effect due to the presence of glass fibers. Moreover, a thermo-gravimetric analysis is carried out and the kinetic parameters of the decomposition reaction extracted from this test with the Friedman method are verified trough a comparison with experimental measurements.

Comparison between several techniques of olive tree bark extraction (Tunisian Chemlali variety).

PubMed

Issaoui, Aimen; Ksibi, Hatem; Ksibi, Mohamed

2017-01-01

In order to better understand the chemical composition of the olive tree bark of Tunisian chemlali variety (Olea europaea cv. 'Chemlali'), this material was extracted by different ways. Compositions of extracts were used at best-selected conditions for each technique, and characterised using HPLC, LC/MS and GC-MS techniques. Analyses are conducted to an important variety of high carbon number compounds such as aliphatic compounds as nanocosane and heptacosane, and molecules with high value added tax (VAT) which can be classified as follows: diterpenes as phytol, triterpenes as squalene and also esters as Benzyl cinnamate. Hydrodistillation at high pressure seems to be a very common method to get a wide variety of compounds, the results are better than the ones obtained using supercritical fluid extraction and solvent extraction.

Proceedings of the 7th Semiannual Meeting of the Nozzle Initiative Industry Advisory Committee on Standardization of Carbon-Phenolic Test Methods and Specifications

NASA Technical Reports Server (NTRS)

Hall, William B. (Compiler); Pinoli, Pat C. (Compiler); Upton, Cindy G. (Compiler)

1991-01-01

The application of carbon fibers and fabrics (CF) for producing rocket nozzles is discussed. These materials which are essential for fabricating the carbon composites used in aerospace systems gasify when exposed to high temperatures and the mechanical properties of the composites degrade. The oxidation kinetics under isothermal (IC) and non-isothermal (NIC) conditions are examined and a comparison is made between the characteristics of IC and NIC oxidation. Several CF, chars, and carbon blacks were examined, including a microporous char, a graphitized rayon fabric, and several carbonized rayon fabrics. A summary is given of the advantages and drawbacks of isothermal and non-isothermal oxidation of carbons. The proceedings are assembled in the form of a roundtable discussion.

Melodic cues for metre.

PubMed

Vos, P G; van Dijk, A; Schomaker, L

1994-01-01

A method of time-series analysis and a time-beating experiment were used to test the structural and perceptual validity of notated metre. Autocorrelation applied to the flow of melodic intervals between notes from thirty fragments of compositions for solo instruments by J S Bach strongly supported the validity of bar length specifications. Time-beating data, obtained with four stimuli from the same set, played in an expressionless mode, and presented under categorically distinct tempos to different subgroups of musically trained subjects, were rather inconsistent with respect to tapped bar lengths. However, taps were most frequently given to the events in the stimuli that corresponded with the first beats according to the score notations. No significant effects of tempo on tapping patterns were observed. The findings are discussed in comparison with other examinations of metre inference from musical compositions.

Applied Integrated Design in Composite UAV Development

NASA Astrophysics Data System (ADS)

Vasić, Zoran; Maksimović, Stevan; Georgijević, Dragutin

2018-04-01

This paper presents a modern approach to integrated development of Unmanned Aerial Vehicle made of laminated composite materials from conceptual design, through detail design, strength and stiffness analyses, definition and management of design and production data, detailed tests results and other activities related to development of laminated composite structures with main of its particularities in comparison to metal structures. Special attention in this work is focused to management processes of product data during life cycle of an UAV and experimental tests of its composite wing. Experience shows that the automation management processes of product data during life cycle, as well as processes of manufacturing, are inevitable if a company wants to get cheaper and quality composite aircraft structures. One of the most effective ways of successful management of product data today is Product Life cycle Management (PLM). In terms of the PLM, a spectrum of special measures and provisions has to be implemented when defining fiber-reinforced composite material structures in comparison to designing with metals which is elaborated in the paper.

Assessing compositional variability through graphical analysis and Bayesian statistical approaches: case studies on transgenic crops.

PubMed

Harrigan, George G; Harrison, Jay M

2012-01-01

New transgenic (GM) crops are subjected to extensive safety assessments that include compositional comparisons with conventional counterparts as a cornerstone of the process. The influence of germplasm, location, environment, and agronomic treatments on compositional variability is, however, often obscured in these pair-wise comparisons. Furthermore, classical statistical significance testing can often provide an incomplete and over-simplified summary of highly responsive variables such as crop composition. In order to more clearly describe the influence of the numerous sources of compositional variation we present an introduction to two alternative but complementary approaches to data analysis and interpretation. These include i) exploratory data analysis (EDA) with its emphasis on visualization and graphics-based approaches and ii) Bayesian statistical methodology that provides easily interpretable and meaningful evaluations of data in terms of probability distributions. The EDA case-studies include analyses of herbicide-tolerant GM soybean and insect-protected GM maize and soybean. Bayesian approaches are presented in an analysis of herbicide-tolerant GM soybean. Advantages of these approaches over classical frequentist significance testing include the more direct interpretation of results in terms of probabilities pertaining to quantities of interest and no confusion over the application of corrections for multiple comparisons. It is concluded that a standardized framework for these methodologies could provide specific advantages through enhanced clarity of presentation and interpretation in comparative assessments of crop composition.

A composition joint PDF method for the modeling of spray flames

NASA Technical Reports Server (NTRS)

Raju, M. S.

1995-01-01

This viewgraph presentation discusses an extension of the probability density function (PDF) method to the modeling of spray flames to evaluate the limitations and capabilities of this method in the modeling of gas-turbine combustor flows. The comparisons show that the general features of the flowfield are correctly predicted by the present solution procedure. The present solution appears to provide a better representation of the temperature field, particularly, in the reverse-velocity zone. The overpredictions in the centerline velocity could be attributed to the following reasons: (1) the use of k-epsilon turbulence model is known to be less precise in highly swirling flows and (2) the swirl number used here is reported to be estimated rather than measured.

MixFit: Methodology for Computing Ancestry-Related Genetic Scores at the Individual Level and Its Application to the Estonian and Finnish Population Studies.

PubMed

Haller, Toomas; Leitsalu, Liis; Fischer, Krista; Nuotio, Marja-Liisa; Esko, Tõnu; Boomsma, Dorothea Irene; Kyvik, Kirsten Ohm; Spector, Tim D; Perola, Markus; Metspalu, Andres

2017-01-01

Ancestry information at the individual level can be a valuable resource for personalized medicine, medical, demographical and history research, as well as for tracing back personal history. We report a new method for quantitatively determining personal genetic ancestry based on genome-wide data. Numerical ancestry component scores are assigned to individuals based on comparisons with reference populations. These comparisons are conducted with an existing analytical pipeline making use of genotype phasing, similarity matrix computation and our addition-multidimensional best fitting by MixFit. The method is demonstrated by studying Estonian and Finnish populations in geographical context. We show the main differences in the genetic composition of these otherwise close European populations and how they have influenced each other. The components of our analytical pipeline are freely available computer programs and scripts one of which was developed in house (available at: www.geenivaramu.ee/en/tools/mixfit).

Environmental Justice Assessment for Transportation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mills, G.S.; Neuhauser, K.S.

1999-04-05

Application of Executive Order 12898 to risk assessment of highway or rail transport of hazardous materials has proven difficult; the location and conditions affecting the propagation of a plume of hazardous material released in a potential accident are unknown, in general. Therefore, analyses have only been possible in geographically broad or approximate manner. The advent of geographic information systems and development of software enhancements at Sandia National Laboratories have made kilometer-by-kilometer analysis of populations tallied by U.S. Census Blocks along entire routes practicable. Tabulations of total, or racially/ethnically distinct, populations close to a route, its alternatives, or the broader surroundingmore » area, can then be compared and differences evaluated statistically. This paper presents methods of comparing populations and their racial/ethnic compositions using simple tabulations, histograms and Chi Squared tests for statistical significance of differences found. Two examples of these methods are presented: comparison of two routes and comparison of a route with its surroundings.« less

Delamination measurement of a laminates composite panel due to hole punching based on the focus variation technique

NASA Astrophysics Data System (ADS)

Abdullah, A. B.; Zain, M. S. M.; Abdullah, M. S.; Samad, Z.

2017-07-01

Structural materials, such as composite panels, must be assembled, and such panels are typically constructed via the insertion of a fastener through a drilled hole. The main problem encountered in drilling is delamination, which affects assembly strength. The cost of drilling is also high because of the severe wear on drill bits. The main goal of this research is to develop a new punching method as an alternative to drilling during hole preparation. In this study, the main objective is to investigate the effect of different puncher profiles on the quality of holes punched into carbon fiber reinforcement polymer (CFRP) composite panels. Six types of puncher profiles were fabricated with minimum die clearance (1%), and two quality aspects, namely, incomplete shearing and delamination factor, were measured. The conical puncher incurred the least defects in terms of delamination and yielded an acceptable amount of incomplete shearing in comparison with the other punchers.

Residual stresses investigations in composite samples by speckle interferometry and specimen repositioning

NASA Astrophysics Data System (ADS)

Baldi, Alfonso; Jacquot, Pierre

2003-05-01

Graphite-epoxy laminates are subjected to the "incremental hole-drilling" technique in order to investigate the residual stresses acting within each layer of the composite samples. In-plane speckle interferometry is used to measure the displacement field created by each drilling increment around the hole. Our approach features two particularities (1) we rely on the precise repositioning of the samples in the optical set-up after each new boring step, performed by means of a high precision, numerically controlled milling machine in the workshop; (2) for each increment, we acquire three displacement fields, along the length, the width of the samples, and at 45°, using a single symmetrical double beam illumination and a rotary stage holding the specimens. The experimental protocol is described in detail and the experimental results are presented, including a comparison with strain gages. Speckle interferometry appears as a suitable method to respond to the increasing demand for residual stress determination in composite samples.

Facile Synthesis of Carbon-Coated Spinel Li4Ti5O12/Rutile-TiO2 Composites as an Improved Anode Material in Full Lithium-Ion Batteries with LiFePO4@N-Doped Carbon Cathode.

PubMed

Wang, Ping; Zhang, Geng; Cheng, Jian; You, Ya; Li, Yong-Ke; Ding, Cong; Gu, Jiang-Jiang; Zheng, Xin-Sheng; Zhang, Chao-Feng; Cao, Fei-Fei

2017-02-22

The spinel Li 4 Ti 5 O 12 /rutile-TiO 2 @carbon (LTO-RTO@C) composites were fabricated via a hydrothermal method combined with calcination treatment employing glucose as carbon source. The carbon coating layer and the in situ formed rutile-TiO 2 can effectively enhance the electric conductivity and provide quick Li + diffusion pathways for Li 4 Ti 5 O 12 . When used as an anode material for lithium-ion batteries, the rate capability and cycling stability of LTO-RTO@C composites were improved in comparison with those of pure Li 4 Ti 5 O 12 or Li 4 Ti 5 O 12 /rutile-TiO 2 . Moreover, the potential of approximately 1.8 V rechargeable full lithium-ion batteries has been achieved by utilizing an LTO-RTO@C anode and a LiFePO 4 @N-doped carbon cathode.

Elastomechanics of carbon nanotubes and their compositions

NASA Astrophysics Data System (ADS)

Yakobson, B. I.

1997-03-01

Nanotubes and their compositions have already revealed and promise more of unique mechanical properties, which are due to the three factors, corresponding to three different scales of organization. (i) The strength of the constituent C-C bonds, (ii) the spatial arrangement of these bonds within the tube layers, and (iii) the relatively weak interlayer and intertube forces. While the first has to be addressed by ab initio methods or by parameterization of empirical potentials, the important role of the two others can be investigated on a phenomenological level. Based on our shell model,(B.I. Yakobson, C. Brabec, J. Bernholc, PRL 76, 2511 (1996); also J. Comp.-Aided Mater. Design 3, 173 (1996).) we show how much can reasonably be expected for various mechanical parameters of nanotubes, in torsion, tension/compression, bending etc. Comparison with experimental data poses problems for future studies. We will discuss nanomechanics of NT compositions, their 2D and 3D arrays, largely determined by the weak lateral interactions, mostly of van Der Waals nature.

Enhanced photoelectrical performance of dye-sensitized solar cells with double-layer TiO2 on perovskite SrTiO3 substrate

NASA Astrophysics Data System (ADS)

Liu, Qiuhong; Sun, Qiong; Zhang, Min; Li, Yang; Zhao, Mei; Dong, Lifeng

2016-04-01

In this research, perovskite SrTiO3 particles are synthesized by a hydrothermal method, and TiO2 with a double-layer structure is grown on the SrTiO3 surface by a hydrolysis-condensation process. Structural characterizations reveal that TiO2 comprises of two phases: anatase film at the bottom and single-crystal rutile nanorods grown along the [110] direction on top. The TiO2-SrTiO3 composite film is investigated as photoanode material for dye-sensitized solar cells. In comparison with pure TiO2 and SrTiO3, the composite photoanode shows a much better performance in photoelectric conversion efficiency (1.35 %), which is about 2 and 100 times as efficient as pure TiO2 and SrTiO3, respectively. This indicates that the composite structure can facilitate charge carrier transfer and reduce electron-hole recombination to enhance photoelectrical properties of TiO2-based photoanode materials.

A Comparison of the Properties of Carbon Fiber Epoxy Composites Produced by Non-autoclave with Vacuum Bag Only Prepreg and Autoclave Process

NASA Astrophysics Data System (ADS)

Park, Sang Yoon; Choi, Chi Hoon; Choi, Won Jong; Hwang, Seong Soon

2018-05-01

The non-autoclave curing technique with vacuum bag only (VBO) prepreg has been conceived as a cost-effective manufacturing method for producing high-quality composite part. This study demonstrated the feasibility of improving composite part's performances and established the effective mitigation strategies for manufacturing induced defects, such as internal voids and surface porosity. The experimental results highlighted the fact that voids and surface porosity were clearly dependent on the resin viscosity state at an intermediate dwell stage of the curing process. Thereafter, the enhancement of resin flow could lead to achieving high quality parts with minimal void content (1.3%) and high fiber fraction (53 vol.%). The mechanical testing showed comparable in-plane shear and compressive strength to conventional autoclave. The microscopic observations also supported the evidence of improved interfacial bonding in terms of excellent fiber wet-out and minimal void content for the optimized cure cycle condition.

Approach for validating actinide and fission product compositions for burnup credit criticality safety analyses

DOE PAGES

Radulescu, Georgeta; Gauld, Ian C.; Ilas, Germina; ...

2014-11-01

This paper describes a depletion code validation approach for criticality safety analysis using burnup credit for actinide and fission product nuclides in spent nuclear fuel (SNF) compositions. The technical basis for determining the uncertainties in the calculated nuclide concentrations is comparison of calculations to available measurements obtained from destructive radiochemical assay of SNF samples. Probability distributions developed for the uncertainties in the calculated nuclide concentrations were applied to the SNF compositions of a criticality safety analysis model by the use of a Monte Carlo uncertainty sampling method to determine bias and bias uncertainty in effective neutron multiplication factor. Application ofmore » the Monte Carlo uncertainty sampling approach is demonstrated for representative criticality safety analysis models of pressurized water reactor spent fuel pool storage racks and transportation packages using burnup-dependent nuclide concentrations calculated with SCALE 6.1 and the ENDF/B-VII nuclear data. Furthermore, the validation approach and results support a recent revision of the U.S. Nuclear Regulatory Commission Interim Staff Guidance 8.« less

Stability of large-scale systems with stable and unstable subsystems.

NASA Technical Reports Server (NTRS)

Grujic, Lj. T.; Siljak, D. D.

1972-01-01

The purpose of this paper is to develop new methods for constructing vector Liapunov functions and broaden the application of Liapunov's theory to stability analysis of large-scale dynamic systems. The application, so far limited by the assumption that the large-scale systems are composed of exponentially stable subsystems, is extended via the general concept of comparison functions to systems which can be decomposed into asymptotically stable subsystems. Asymptotic stability of the composite system is tested by a simple algebraic criterion. With minor technical adjustments, the same criterion can be used to determine connective asymptotic stability of large-scale systems subject to structural perturbations. By redefining the constraints imposed on the interconnections among the subsystems, the considered class of systems is broadened in an essential way to include composite systems with unstable subsystems. In this way, the theory is brought substantially closer to reality since stability of all subsystems is no longer a necessary assumption in establishing stability of the overall composite system.

Phylogenetic analysis of a spontaneous cocoa bean fermentation metagenome reveals new insights into its bacterial and fungal community diversity.

PubMed

Illeghems, Koen; De Vuyst, Luc; Papalexandratou, Zoi; Weckx, Stefan

2012-01-01

This is the first report on the phylogenetic analysis of the community diversity of a single spontaneous cocoa bean box fermentation sample through a metagenomic approach involving 454 pyrosequencing. Several sequence-based and composition-based taxonomic profiling tools were used and evaluated to avoid software-dependent results and their outcome was validated by comparison with previously obtained culture-dependent and culture-independent data. Overall, this approach revealed a wider bacterial (mainly γ-Proteobacteria) and fungal diversity than previously found. Further, the use of a combination of different classification methods, in a software-independent way, helped to understand the actual composition of the microbial ecosystem under study. In addition, bacteriophage-related sequences were found. The bacterial diversity depended partially on the methods used, as composition-based methods predicted a wider diversity than sequence-based methods, and as classification methods based solely on phylogenetic marker genes predicted a more restricted diversity compared with methods that took all reads into account. The metagenomic sequencing analysis identified Hanseniaspora uvarum, Hanseniaspora opuntiae, Saccharomyces cerevisiae, Lactobacillus fermentum, and Acetobacter pasteurianus as the prevailing species. Also, the presence of occasional members of the cocoa bean fermentation process was revealed (such as Erwinia tasmaniensis, Lactobacillus brevis, Lactobacillus casei, Lactobacillus rhamnosus, Lactococcus lactis, Leuconostoc mesenteroides, and Oenococcus oeni). Furthermore, the sequence reads associated with viral communities were of a restricted diversity, dominated by Myoviridae and Siphoviridae, and reflecting Lactobacillus as the dominant host. To conclude, an accurate overview of all members of a cocoa bean fermentation process sample was revealed, indicating the superiority of metagenomic sequencing over previously used techniques.

Effects of three drying methods of post space dentin bonding used in a direct resin composite core build-up method.

PubMed

Iwashita, Taichi; Mine, Atsushi; Matsumoto, Mariko; Nakatani, Hayaki; Higashi, Mami; Kawaguchi-Uemura, Asuka; Kabetani, Tomoshige; Tajiri, Yuko; Imai, Dai; Hagino, Ryosuke; Miura, Jiro; Minamino, Takuya; Yatani, Hirofumi

2018-06-14

The purpose of this study was to evaluate drying methods for post space dentin bonding in a direct resin composite core build-up method. Experiment 1: Four root canal plastic models, having diameters of 1.0 or 1.8mm and parallel or tapered shapes, were prepared. After drying each post space using three drying methods (air drying, paper-point drying, or ethanol drying, which involves filling the space with 99.5 vol% ethanol followed by air drying), the residual liquid in the models was weighed. Experiment 2: Thirty endodontically treated single-root teeth were dried using the above-described drying methods and filled with dual-cure resin composite. The bonded specimens were sectioned into square beams of approximately 1mm 2 for microtensile bond strength (μTBS) testing. Nine teeth were observed through transmission electron microscopy (TEM) and micro computed tomography (μCT). The weight of residual liquid and μTBS were analyzed using Scheffé multiple comparison. Experiment 1: The results of air drying were significantly different from those of paper-point drying (p<0.001) and ethanol drying (p<0.001), and no significant difference was observed between paper-point drying and ethanol drying. Experiment 2: The μTBS significantly decreased in the order of ethanol drying, paper-point drying, and air drying (air drying/ethanol drying: p<0.001, air drying/paper-point drying: p=0.048, ethanol drying/paper-point drying: p=0.032). TEM and μCT observation revealed a sufficient dentin/adhesive interface in the ethanol drying group. Ethanol drying was found to be more effective for post space dentin bonding, as compared with air drying and paper-point drying. Copyright © 2018 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Composition of gaseous organic carbon during ECOCEM in Beirut, Lebanon: new observational constraints for VOC anthropogenic emission evaluation in the Middle East

NASA Astrophysics Data System (ADS)

Salameh, Thérèse; Borbon, Agnès; Afif, Charbel; Sauvage, Stéphane; Leonardis, Thierry; Gaimoz, Cécile; Locoge, Nadine

2017-01-01

The relative importance of eastern Mediterranean emissions is suspected to be largely underestimated compared to other regions worldwide. Here we use detailed speciated measurements of volatile organic compounds (VOCs) to evaluate the spatial heterogeneity of VOC urban emission composition and the consistency of regional and global emission inventories downscaled to Lebanon (European Monitoring and Evaluation Programme, EMEP; Atmospheric Chemistry and Climate Model Intercomparison Project, ACCMIP; and MACCity, Monitoring Atmospheric Composition and Climate and megaCITY Zoom for the Environment). The assessment was conducted through the comparison of the emission ratios (ERs) extracted from the emission inventories to the ones obtained from the hourly observations collected at a suburban site in Beirut, Lebanon, during summer and winter ECOCEM (Emissions and Chemistry of Organic Carbon in the Eastern Mediterranean) campaigns. The observed ERs were calculated using two independent methods. ER values from both methods agree very well and are comparable to the ones of the road transport sector from near-field measurements for more than 80 % of the species. There is no significant seasonality in ER for more than 90 % of the species, unlike the seasonality usually observed in other cities worldwide. Regardless of the season, ERs agree within a factor of 2 between Beirut and other representative cities worldwide, except for the unburned fuel fraction and ethane. ERs of aromatics (except benzene) are higher in Beirut compared to northern post-industrialized countries and even the Middle Eastern city Mecca. The comparison of the observed ER to the ones extracted from the ACCMIP and MACCity global emission inventories suggests that the overall speciation of anthropogenic sources for major hydrocarbons that act as ozone and secondary organic aerosol (SOA) precursors in ACCMIP is better represented than other species. The comparison of the specific road transport ERs, relative to acetylene derived from near-field measurements, to ERs from ACCMIP and EMEP emission inventories for the road transport sector showed that ERs of more reactive species are usually consistent within a factor of 2 with EMEP, while xylenes and toluene are underestimated by over a factor of 2 by ACCMIP. The observed heterogeneity of anthropogenic VOC emission composition between Middle Eastern cities can be significant for reactive VOCs but is not depicted by global emission inventories. This suggests that systematic and detailed measurements are needed in the eastern Mediterranean Basin in order to better constrain emission inventory.

Materials with periodic internal structure: Computation based on homogenization and comparison with experiment

NASA Technical Reports Server (NTRS)

Jansson, S.; Leckie, F. A.; Onat, E. T.; Ranaweera, M. P.

1990-01-01

The combination of thermal and mechanical loading expected in practice means that constitutive equations of metal matrix composites must be developed which deal with time-independent and time-dependent irreversible deformation. Also, the internal state of composites is extremely complicated which underlines the need to formulate macroscopic constitutive equations with a limited number of state variables which represent the internal state at the micro level. One available method for calculating the macro properties of composites in terms of the distribution and properties of the constituent materials is the method of homogenization whose formulation is based on the periodicity of the substructure of the composite. A homogenization procedure was developed which lends itself to the use of the finite element procedure. The efficiency of these procedures, to determine the macroscopic properties of a composite system from its constituent properties, was demonstrated utilizing an aluminum plate perforated by directionally oriented slits. The selection of this problem is based on the fact that, extensive experimental results exist, the macroscopic response is highly anisotropic, and that the slits provide very high stress gradients which severely test the effectiveness of the computational procedures. Furthermore, both elastic and plastic properties were investigated so that the application to practical systems with inelastic deformation should be able to proceed without difficulty. The effectiveness of the procedures was rigorously checked against experimental results and with the predictions of approximate calculations. Using the computational results it is illustrated how macroscopic constitutive equations can be expressed in forms of the elastic and limit load behavior.

International comparison CCQM-K119 liquefied petroleum gas

NASA Astrophysics Data System (ADS)

Brewer, P. J.; Downey, M. L.; Atkins, E.; Brown, R. J. C.; Brown, A. S.; Zalewska, E. T.; van der Veen, A. M. H.; Smeulders, D. E.; McCallum, J. B.; Satumba, R. T.; Kim, Y. D.; Kang, N.; Bae, H. K.; Woo, J. C.; Konopelko, L. A.; Popova, T. A.; Meshkov, A. V.; Efremova, O. V.; Kustikov, Y.

2018-01-01

Liquefied hydrocarbon mixtures with traceable composition are required in order to underpin measurements of the composition and other physical properties of LPG (liquefied petroleum gas), thus meeting the needs of an increasingly large industrial market. This comparison aims to assess the analytical capabilities of laboratories for measuring the composition of a Liquid Petroleum Gas (LPG) mixture when sampled in the liquid phase from a Constant Pressure Cylinder. Mixtures contained ethane, propane, propene, i-butane, n-butane, but-1-ene and i-pentane with nominal amount fractions of 2, 71, 9, 4, 10, 3 and 1 cmol mol-1 respectively. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Prognostic Health Management of DoD Assets

DTIC Science & Technology

2015-06-01

34Acoustic emission for monitoring the mechanical behaviour of natural fibre composites: a literature review," Composites Part A: Applied Science and...34Acoustic emission of debonding between fibre and matrix to evaluate local adhesion," Composites Science and Technology, vol. 63, pp. 2155-2162, 2003...classification in carbon fibre composites using acoustic emission: A comparison of three techniques," Composites Part B: Engineering, vol. 68, pp. 424-430, 1

Phosphorescent compositions, methods of making the compositions, and methods of using the compositions

DOEpatents

Jia, Weiyi; Wang, Xiaojun; Yen, William; Yen, Laurel C.; Jia, George D.

2012-12-04

Compositions, methods of making compositions, materials including compositions, crayons including compositions, paint including compositions, ink including compositions, waxes including compositions, polymers including compositions, vesicles including the compositions, methods of making each, and the like are disclosed.

Phosphorescent compositions, methods of making the compositions, and methods of using the compositions

DOEpatents

Jia, Weiyi; Wang, Xiaojun; Jia, George D.; Lewis, Linda; Yen, Laurel C.

2014-06-24

Compositions, methods of making compositions, materials including compositions, crayons including compositions, paint including compositions, ink including compositions, waxes including compositions, polymers including compositions, vesicles including the compositions, methods of making each, and the like are disclosed.

PM2.5 Technology Assessment and Characterization Study in New York - PMTACS-NY: The 2001 Summer Field Intensive in Queens, NY

NASA Astrophysics Data System (ADS)

Demerjian, K. L.

2002-12-01

In the summer of 2001, an intensive field measurement campaign was carried out in Queens, NY as part of the PM2.5 Technology Assessment and Characterization Study in New York (PMTACS-NY) to characterize the physical and chemical composition of particulate matter and related precursors utilizing conventional and advanced instrumentation technologies. The measurement program, involving a team of scientists from federal, state, university and private sector organizations, was designed to provide detailed time resolved chemical and physical characterization of the urban PM2.5/co-pollutant complex in relation to the regional environment. A summary of the chemical and meteorological data defining specific events during the field intensive is presented as are results addressing specific hypothesis designed around PMTACS-NY program objectives. These include initial findings and conclusions related to 1) performance testing and evaluation of emerging measurement technologies and comparison with EPA mandated PM federal reference methods currently operational as part of the New York State and national PM2.5 monitoring network; 2) emissions characterization of CNG, standard diesel and CRT (Continuously Regenerating Technology) diesel retrofit powered vehicles; and 3) compositional comparisons of urban and regional PM2.5.

Changes in body composition over 8 years in a randomized trial of a lifestyle intervention: the look AHEAD study.

PubMed

Pownall, Henry J; Bray, George A; Wagenknecht, Lynne E; Walkup, Michael P; Heshka, Stanley; Hubbard, Van S; Hill, James; Kahn, Steven E; Nathan, David M; Schwartz, Anne V; Johnson, Karen C

2015-03-01

To determine the effects of an intensive lifestyle intervention versus a comparison group on body composition in obese or overweight persons with type 2 diabetes at baseline and at 1, 4, and 8 years. Body composition was measured by dual-energy X-ray absorptiometry in a subset of 1019 Look AHEAD study volunteers randomized to intervention or comparison groups. The intervention was designed to achieve and maintain ≥7% weight loss through increased physical activity and reduced caloric intake. The comparison group received social support and diabetes education. At 1 year, the intervention group lost fat (5.6 ± 0.2 kg) and lean mass (2.3 ± 0.1 kg) but regained fat (∼100%) and lost lean mass between years 1 and 8. Between baseline and year 8, weight loss was greater in intervention versus comparison groups (4.0 ± 0.4 vs. 2.3 ± 0.4 kg); comparison group weight loss was mostly lean mass (2.1 ± 0.17 kg). Fat mass in the intervention group was lower than that of the comparison group at all post-baseline time points. Reduced fat mass may place the intervention group at a lower risk of obesity-linked sequelae, a hypothesis that can be tested by future studies of this cohort. © 2015 The Obesity Society.

The Composition of M-type Asteroids: Synthesis of Spectroscopic and Radar Observations.

NASA Astrophysics Data System (ADS)

Bell, Maureen; Clark, B. E.; Shepard, M. K.; Issacs, R. A.; Cloutis, E. A.; Fornasier, S.; Bus, S. J.

2010-10-01

We have conducted a radar-driven observational campaign of 22 main-belt asteroids (MBAs) focused on Bus-DeMeo Xc- and Xk-type objects (Tholen X and M class asteroids) using the Arecibo radar and NASA Infrared Telescope Facilities (IRTF). Sixteen of our targets were near-simultaneously observed with radar. We find that most of the highest metal-content asteroids, as suggested by radar, tend to exhibit silicate absorption features at both 0.9 and 1.9 microns, and the lowest metal-content asteroids tend to exhibit either no bands or only the 0.9 microns band. Eleven of the asteroids were observed at several rotational longitudes in the near-infrared and significant variations in continuum slope were found for nine in the spectral regions 1.1-1.45 microns and 1.6-2.3 microns. Compositional evidence is derived from our target asteroid spectra using two different methods: 1) a Chi-squared search for spectral matches in the RELAB database, and 2) parametric comparisons with meteorites. We find that for four of the seven asteroids with the highest iron abundances, our spectral results are consistent with each other and with the radar evidence pointing to an iron meteorite composition (16 Psyche, 216 Kleopatra, 347 Pariana, and 779 Nina). Four asteroids have radar analogs consistent with either our parametric comparison or our RELAB analog type (21 Lutetia, 135 Hertha, 497 Iva, and 758 Mancunia ). The remaining eight asteroids (22 Kalliope, 97 Klotho, 110 Lydia, 129 Antigone, 224 Oceana, 678 Fredegundis, 771 Libera, and 785 Zwetana) have ambiguous compositional interpretations when comparing the spectral analogs to the radar analogs.

Online analysis of chlorine stable isotopes in chlorinated ethylenes: an inter-laboratory study

NASA Astrophysics Data System (ADS)

Bernstein, Anat; Shouakar-Stash, Orfan; Hunkeler, Daniel; Sakaguchi-Söder, Kaori; Laskov, Christine; Aravena, Ramon; Elsner, Martin

2010-05-01

In the last decade, compound-specific stable isotopes analysis of groundwater pollutants became an important tool to identify different sources of the same pollutant and for tracking natural attenuating processes in the sub-surface. It has been shown that trends in the isotopic composition of the target compounds can shed light on in-situ processes that are otherwise difficult to track. Analytical methods of carbon, nitrogen and hydrogen were established and are by now frequently used for a variety of organic pollutants. Yet, the motivation of introducing analytical methods for new isotopes is emerging. This motivation is further enhanced, as advantages of using two or more stable isotopes for gaining better insight on degradation pathways are well accepted. One important element which demands the development of appropriate analytical methods is chlorine, which is found in various groups of organic pollutants, among them the chlorinated ethylenes. Chlorinated ethylenes are considered as high priority environmental pollutants, and the development of suitable chlorine isotope methods for this group of pollutants is highly desired. Ideally, stable isotope techniques should have the capability to determine the isotopic composition of and individual target compound in a non-pure mixture, without the requirement of a laborious off-line treatment. Indeed, in the last years two different concepts for on-line chlorine isotope analysis methods were introduced, by using either a standard quadrapole GC/MS (Sakaguchi-Söder et al., 2007) or by using a GC/IRMS (Shouakar-Stash et al., 2006). We present a comparison of the performances of two concepts, carried out in five different laboratories: Waterloo (GC/IRMS), Neuchâtel (GC/MS), Darmstadt (GC/MS), Tübingen (GC/MS) and Munich (GC/IRMS). This comparison was performed on pure trichloroethylene and dichloroethylene products of different manufactures, as well as trichloroethylene and dichloroethylene samples that were exposed to biodegradation. This study sets standards for further application of these techniques to distinguish sources and track degradation processes in the sub-surface.

Calculation of water equivalent thickness of materials of arbitrary density, elemental composition and thickness in proton beam irradiation

NASA Astrophysics Data System (ADS)

Zhang, Rui; Newhauser, Wayne D.

2009-03-01

In proton therapy, the radiological thickness of a material is commonly expressed in terms of water equivalent thickness (WET) or water equivalent ratio (WER). However, the WET calculations required either iterative numerical methods or approximate methods of unknown accuracy. The objective of this study was to develop a simple deterministic formula to calculate WET values with an accuracy of 1 mm for materials commonly used in proton radiation therapy. Several alternative formulas were derived in which the energy loss was calculated based on the Bragg-Kleeman rule (BK), the Bethe-Bloch equation (BB) or an empirical version of the Bethe-Bloch equation (EBB). Alternative approaches were developed for targets that were 'radiologically thin' or 'thick'. The accuracy of these methods was assessed by comparison to values from an iterative numerical method that utilized evaluated stopping power tables. In addition, we also tested the approximate formula given in the International Atomic Energy Agency's dosimetry code of practice (Technical Report Series No 398, 2000, IAEA, Vienna) and stopping power ratio approximation. The results of these comparisons revealed that most methods were accurate for cases involving thin or low-Z targets. However, only the thick-target formulas provided accurate WET values for targets that were radiologically thick and contained high-Z material.

Sequential extraction protocol for organic matter from soils and sediments using high resolution mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tfaily, Malak M.; Chu, Rosalie K.; Toyoda, Jason

A vast number of organic compounds are present in soil organic matter (SOM) and play an important role in the terrestrial carbon cycle, facilitate interactions between organisms, and represent a sink for atmospheric CO2. The diversity of different SOM compounds and their molecular characteristics is a function of the organic source material and biogeochemical history. By understanding how SOM composition changes with sources and the processes by which it is biogeochemically altered in different terrestrial ecosystems, it may be possible to predict nutrient and carbon cycling, response to system perturbations, and impact of climate change will have on SOM composition.more » In this study, a sequential chemical extraction procedure was developed to reveal the diversity of organic matter (OM) in different ecosystems and was compared to the previously published protocol using parallel solvent extraction (PSE). We compared six extraction methods using three sample types, peat soil, spruce forest soil and river sediment, so as to select the best method for extracting a representative fraction of organic matter from soils and sediments from a wide range of ecosystems. We estimated the extraction yield of dissolved organic carbon (DOC) by total organic carbon analysis, and measured the composition of extracted OM using high resolution mass spectrometry. This study showed that OM composition depends primarily on soil and sediment characteristics. Two sequential extraction protocols, progressing from polar to non-polar solvents, were found to provide the highest number and diversity of organic compounds extracted from the soil and sediments. Water (H2O) is the first solvent used for both protocols followed by either co-extraction with methanol-chloroform (MeOH-CHCl3) mixture, or acetonitrile (ACN) and CHCl3 sequentially. The sequential extraction protocol developed in this study offers improved sensitivity, and requires less sample compared to the PSE workflow where a new sample is used for each solvent type. Furthermore, a comparison of SOM composition from the different sample types revealed that our sequential protocol allows for ecosystem comparisons based on the diversity of compounds present, which in turn could provide new insights about source and processing of organic compounds in different soil and sediment types.« less

Sequential extraction protocol for organic matter from soils and sediments using high resolution mass spectrometry.

PubMed

Tfaily, Malak M; Chu, Rosalie K; Toyoda, Jason; Tolić, Nikola; Robinson, Errol W; Paša-Tolić, Ljiljana; Hess, Nancy J

2017-06-15

A vast number of organic compounds are present in soil organic matter (SOM) and play an important role in the terrestrial carbon cycle, facilitate interactions between organisms, and represent a sink for atmospheric CO 2 . The diversity of different SOM compounds and their molecular characteristics is a function of the organic source material and biogeochemical history. By understanding how SOM composition changes with sources and the processes by which it is biogeochemically altered in different terrestrial ecosystems, it may be possible to predict nutrient and carbon cycling, response to system perturbations, and impact of climate change will have on SOM composition. In this study, a sequential chemical extraction procedure was developed to reveal the diversity of organic matter (OM) in different ecosystems and was compared to the previously published protocol using parallel solvent extraction (PSE). We compared six extraction methods using three sample types, peat soil, spruce forest soil and river sediment, so as to select the best method for extracting a representative fraction of organic matter from soils and sediments from a wide range of ecosystems. We estimated the extraction yield of dissolved organic carbon (DOC) by total organic carbon analysis, and measured the composition of extracted OM using high resolution mass spectrometry. This study showed that OM composition depends primarily on soil and sediment characteristics. Two sequential extraction protocols, progressing from polar to non-polar solvents, were found to provide the highest number and diversity of organic compounds extracted from the soil and sediments. Water (H 2 O) is the first solvent used for both protocols followed by either co-extraction with methanol-chloroform (MeOH-CHCl 3 ) mixture, or acetonitrile (ACN) and CHCl 3 sequentially. The sequential extraction protocol developed in this study offers improved sensitivity, and requires less sample compared to the PSE workflow where a new sample is used for each solvent type. Furthermore, a comparison of SOM composition from the different sample types revealed that our sequential protocol allows for ecosystem comparisons based on the diversity of compounds present, which in turn could provide new insights about source and processing of organic compounds in different soil and sediment types. Copyright © 2017 Elsevier B.V. All rights reserved.

[Sex as a variable in research in psychotherapy, psychosomatic and medical psychology].

PubMed

Davies-Osterkamp, S

1994-01-01

All empirical studies (n = 113) published in "Psychotherapie, Psychosomatik, medizinische Psychologie" between 1988 and 1992 where analyzed concerning the question whether sex comparisons in at least one of the dependent variables were reported. The main results were that sex composition of the samples was not reported in 17% of the cases and that 62% of the studies did not report on sex comparisons. Only 25% of studies reported on sex differences in a metric which allows using this study for meta-analysis. Except for sample-size and sex-composition there were no study-features which distinguished between studies reporting or not reporting sex comparisons.

A multifaceted comparison of ArcGIS and MapMarker for automated geocoding.

PubMed

Kumar, Sanjaya; Liu, Ming; Hwang, Syni-An

2012-11-01

Geocoding is increasingly being used for public health surveillance and spatial epidemiology studies. Public health departments in the United States of America (USA) often use this approach to investigate disease outbreaks and clusters or assign health records to appropriate geographic units. We evaluated two commonly used geocoding software packages, ArcGIS and MapMarker, for automated geocoding of a large number of residential addresses from health administrative data in New York State, USA to better understand their features, performance and limitations. The comparison was based on three metrics of evaluation: completeness (or match rate), geocode similarity and positional accuracy. Of the 551,798 input addresses, 318,302 (57.7%) were geocoded by MapMarker and 420,813 (76.3%) by the ArcGIS composite address locator. High similarity between the geocodes assigned by the two methods was found, especially in suburban and urban areas. Among addresses with a distance of greater than 100 m between the geocodes assigned by the two packages, the point assigned by ArcGIS was closer to the associated parcel centroid ("true" location) compared with that assigned by MapMarker. In addition, the composite address locator in ArcGIS allows users to fully utilise available reference data, which consequently results in better geocoding results. However, the positional differences found were minimal, and a large majority of addresses were placed on the same locations by both geocoding packages. Using both methods and combining the results can maximise match rates and save the time needed for manual geocoding.

Durability and mechanical properties of silane cross-linked wood thermoplastic composites

Treesearch

Magnus Bengtsson; Nicole M. Stark; Kristiina Oksman

2007-01-01

In this study, silane cross-linked wood–polyethylene composite profiles were manufactured by reactive extrusion. These composites were evaluated regarding their durability and mechanical properties in comparison with two non-cross-linked wood– polyethylene composites. An addition of only 2% w/w of silane solution during manufacturing was enough to achieve almost 60%...

Cellular Magnesium Matrix Foam Composites for Mechanical Damping Applications

NASA Astrophysics Data System (ADS)

Shunmugasamy, Vasanth Chakravarthy; Mansoor, Bilal; Gupta, Nikhil

2016-01-01

The damping characteristics of metal alloys and metal matrix composites are relevant to the automotive, aerospace, and marine structures. Use of lightweight materials can help in increasing payload capacity and in decreasing fuel consumption. Lightweight composite materials possessing high damping capabilities that can be designed as structural members can greatly benefit in addressing these needs. In this context, the damping properties of lightweight metals such as aluminum and magnesium and their respective composites have been studied in the existing literature. This review focuses on analyzing the damping properties of aluminum and magnesium alloys and their cellular composites. The damping properties of various lightweight alloys and composites are compared on the basis of their density to understand the potential for weight saving in structural applications. Magnesium alloys are observed to possess better damping properties in comparison to aluminum. However, aluminum matrix syntactic foams reinforced with silicon carbide hollow particles possess a damping capacity and density comparable to magnesium alloy. By using the data presented in the study, composites with specific compositions and properties can be selected for a given application. In addition, the comparison of the results helps in identifying the areas where attention needs to be focused to address the future needs.

Comparison of Cyclic Hysteresis Behavior between Cross-Ply C/SiC and SiC/SiC Ceramic-Matrix Composites

PubMed Central

Li, Longbiao

2016-01-01

In this paper, the comparison of cyclic hysteresis behavior between cross-ply C/SiC and SiC/SiC ceramic-matrix composites (CMCs) has been investigated. The interface slip between fibers and the matrix existed in the matrix cracking mode 3 and mode 5, in which matrix cracking and interface debonding occurred in the 0° plies are considered as the major reason for hysteresis loops of cross-ply CMCs. The hysteresis loops of cross-ply C/SiC and SiC/SiC composites corresponding to different peak stresses have been predicted using present analysis. The damage parameter, i.e., the proportion of matrix cracking mode 3 in the entire matrix cracking modes of the composite, and the hysteresis dissipated energy increase with increasing peak stress. The damage parameter and hysteresis dissipated energy of C/SiC composite under low peak stress are higher than that of SiC/SiC composite; However, at high peak stress, the damage extent inside of cross-ply SiC/SiC composite is higher than that of C/SiC composite as more transverse cracks and matrix cracks connect together. PMID:28787861

Comparison of Cyclic Hysteresis Behavior between Cross-Ply C/SiC and SiC/SiC Ceramic-Matrix Composites.

PubMed

Li, Longbiao

2016-01-19

In this paper, the comparison of cyclic hysteresis behavior between cross-ply C/SiC and SiC/SiC ceramic-matrix composites (CMCs) has been investigated. The interface slip between fibers and the matrix existed in the matrix cracking mode 3 and mode 5, in which matrix cracking and interface debonding occurred in the 0° plies are considered as the major reason for hysteresis loops of cross-ply CMCs. The hysteresis loops of cross-ply C/SiC and SiC/SiC composites corresponding to different peak stresses have been predicted using present analysis. The damage parameter, i.e. , the proportion of matrix cracking mode 3 in the entire matrix cracking modes of the composite, and the hysteresis dissipated energy increase with increasing peak stress. The damage parameter and hysteresis dissipated energy of C/SiC composite under low peak stress are higher than that of SiC/SiC composite; However, at high peak stress, the damage extent inside of cross-ply SiC/SiC composite is higher than that of C/SiC composite as more transverse cracks and matrix cracks connect together.

Impedance Based Detection of Delamination in Composite Structures

NASA Astrophysics Data System (ADS)

Djemana, M.; Hrairi, M.

2017-03-01

Nowadays commercial and military aircrafts are increasingly using composite materials to take advantage of their excellent specific strength and stiffness properties but impacts on composites due to bird-strike, hail-storm cause barely visible impact damage (BVID) that underscores the need for robust structural health monitoring methods. Hence, damage identification in composite materials is a widely researched area that has to deal with problems coming from the anisotropic nature of composites and the fact that much of the damage occurs beneath the top surface of the laminate. This paper focuses on understanding self-sensing piezoelectric wafer active sensors (PWAS) to conduct electromechanical impedance (EMI) in glass fibre reinforced polymer composite to perform structural health monitoring. With the aid of a 3D ANSYS finite element model, an analysis of different techniques for the detection of position and size of a delamination in a composite structure using piezoelectric patches had been performed. The real part of the impedance is used because it is known to be more reactive to damage or changes in the structure’s integrity and less sensitive to ambient temperature changes compared to the imaginary part. Comparison with experimental results is presented to validate the FE results. The experimental setup utilizes as its main apparatus an impedance analyser HP4194 that reads the in-situ EMI of PWAS bonded to the monitored composite structure. A good match between experimental and numerical results has been observed for low and high frequencies. The analysis in this paper provides necessary basis for delamination detection in composite structures using EMI technique

Comprehensive Assessment of Composition and Thermochemical Variability by High Resolution GC/QToF-MS and the Advanced Distillation-Curve Method as a Basis of Comparison for Reference Fuel Development*

PubMed Central

Lovestead, Tara M.; Burger, Jessica L.; Schneider, Nico; Bruno, Thomas J.

2018-01-01

Commercial and military aviation is faced with challenges that include high fuel costs, undesirable emissions, and supply chain insecurity that result from the reliance on petroleum-based feedstocks. The development of alternative gas turbine fuels from renewable resources will likely be part of addressing these issues. The United States has established a target for one billion gallons of renewable fuels to enter the supply chain by 2018. These alternative fuels will have to be very similar in properties, chemistry, and composition to existing fuels. To further this goal, the National Jet Fuel Combustion Program (a collaboration of multiple U.S. agencies under the auspices of the Federal Aviation Administration, FAA) is coordinating measurements on three reference gas turbine fuels to be used as a basis of comparison. These fuels are reference fuels with certain properties that are at the limits of experience. These fuels include a low viscosity, low flash point, high hydrogen content “best case” JP-8 (POSF 10264) fuel, a relatively high viscosity, high flash point, low hydrogen content “worst case” JP-5 (POSF 10259) fuel, and a Jet-A (POSF 10325) fuel with relatively average properties. A comprehensive speciation of these fuels is provided in this paper by use of high resolution gas chromatography/quadrupole time-of-flight – mass spectrometry (GC/QToF-MS), which affords unprecedented resolution and exact molecular formula capabilities. The volatility information as derived from the measurement of the advanced distillation curve temperatures, Tk and Th, provides an approximation of the vapor liquid equilibrium and examination of the composition channels provides detailed insight into thermochemical data. A comprehensive understanding of the compositional and thermophysical data of gas turbine fuels is required not only for comparison but also for modeling of such complex mixtures, which will, in turn, aid in the development of new fuels with the goals of diversified feedstocks, decreased pollution, and increased efficiency. PMID:29706688

Electric Composition Cost Comparison.

ERIC Educational Resources Information Center

Joint Committee on Printing, Washington, DC.

Experience of the U.S. Government Printing Office and others has shown that electronic composition of computer processed data is more economical than printing from camera copy produced by the line printers of digital computers. But electronic composition of data not already being processed by computer is not necessarily economical. This analysis…

Toxicity testing of restorative dental materials using brine shrimp larvae (Artemia salina).

PubMed

Milhem, Manar M; Al-Hiyasat, Ahmad S; Darmani, Homa

2008-01-01

This study investigated the effect of extracts of different composites, glass ionomer cement (GIC)s and compomers on the viability of brine shrimp larvae. Ethanolic extracts of four dental composites (Z-100; Solitaire 2; Filtek P60 and Synergy), a conventional GIC (Ketac-Fil), a resin-modified glass ionomer cement (Vitremer), two compomers (F2000; Dyract AP), and a flowable compomer (Dyract Flow) were prepared from each material. Following evaporation of the ethanol, the extracts were resuspended in distilled water, which was then used to test the effects on the viability of brine shrimp larvae. For the composites, the extract of Synergy was the least toxic (88% viability) followed by the extracts of Solitaire 2, Z100 and P60 (75%, 67.5% and 50% viability, respectively). One-way ANOVA revealed highly significant differences between the resin composite materials (p<0.001). Follow-up comparison between the composite groups by Tukey's pairwise multiple-comparison test (alpha =0.05) showed that the extract of Synergy was significantly less toxic than the extracts of all the other materials except that of Solitaire 2. The compomers showed 100% lethality, while the percentage of viable larvae for the extracts of Ketac-Fil, and Vitremer were 32.3%, and 37.0%, respectively. One-way ANOVA revealed highly significant differences between the groups of materials (p<0.001). Follow-up comparison between the groups by Tukey's test (alpha = 0.05) showed that the toxic effect of the extracts of the compomers were significantly greater than that of Ketac-Fil, and Vitremer. The differences in the toxic effects of Vitremer and Ketac-Fil were not statistically significant. In conclusion, the toxicity of composite materials varied according to their chemical composition. Compomers were the most lethal materials to brine shrimp larvae followed by GICs and then composites.

Validation of a Tablet Application for Assessing Dietary Intakes Compared with the Measured Food Intake/Food Waste Method in Military Personnel Consuming Field Rations.

PubMed

Ahmed, Mavra; Mandic, Iva; Lou, Wendy; Goodman, Len; Jacobs, Ira; L'Abbé, Mary R

2017-02-27

The collection of accurate dietary intakes using traditional dietary assessment methods (e.g., food records) from military personnel is challenging due to the demanding physiological and psychological conditions of training or operations. In addition, these methods are burdensome, time consuming, and prone to measurement errors. Adopting smart-phone/tablet technology could overcome some of these barriers. The objective was to assess the validity of a tablet app, modified to contain detailed nutritional composition data, in comparison to a measured food intake/waste method. A sample of Canadian Armed Forces personnel, randomized to either a tablet app ( n = 9) or a weighed food record (wFR) ( n = 9), recorded the consumption of standard military rations for a total of 8 days. Compared to the gold standard measured food intake/waste method, the difference in mean energy intake was small (-73 kcal/day for tablet app and -108 kcal/day for wFR) ( p > 0.05). Repeated Measures Bland-Altman plots indicated good agreement for both methods (tablet app and wFR) with the measured food intake/waste method. These findings demonstrate that the tablet app, with added nutritional composition data, is comparable to the traditional dietary assessment method (wFR) and performs satisfactorily in relation to the measured food intake/waste method to assess energy, macronutrient, and selected micronutrient intakes in a sample of military personnel.

Validation of a Tablet Application for Assessing Dietary Intakes Compared with the Measured Food Intake/Food Waste Method in Military Personnel Consuming Field Rations

PubMed Central

Ahmed, Mavra; Mandic, Iva; Lou, Wendy; Goodman, Len; Jacobs, Ira; L’Abbé, Mary R.

2017-01-01

The collection of accurate dietary intakes using traditional dietary assessment methods (e.g., food records) from military personnel is challenging due to the demanding physiological and psychological conditions of training or operations. In addition, these methods are burdensome, time consuming, and prone to measurement errors. Adopting smart-phone/tablet technology could overcome some of these barriers. The objective was to assess the validity of a tablet app, modified to contain detailed nutritional composition data, in comparison to a measured food intake/waste method. A sample of Canadian Armed Forces personnel, randomized to either a tablet app (n = 9) or a weighed food record (wFR) (n = 9), recorded the consumption of standard military rations for a total of 8 days. Compared to the gold standard measured food intake/waste method, the difference in mean energy intake was small (−73 kcal/day for tablet app and −108 kcal/day for wFR) (p > 0.05). Repeated Measures Bland-Altman plots indicated good agreement for both methods (tablet app and wFR) with the measured food intake/waste method. These findings demonstrate that the tablet app, with added nutritional composition data, is comparable to the traditional dietary assessment method (wFR) and performs satisfactorily in relation to the measured food intake/waste method to assess energy, macronutrient, and selected micronutrient intakes in a sample of military personnel. PMID:28264428

Pre-flight calibration and initial data processing for the ChemCam laser-induced breakdown spectroscopy instrument on the Mars Science Laboratory rover

USGS Publications Warehouse

Wiens, R.C.; Maurice, S.; Lasue, J.; Forni, O.; Anderson, R.B.; Clegg, S.; Bender, S.; Blaney, D.; Barraclough, B.L.; Cousin, A.; DeFlores, L.; Delapp, D.; Dyar, M.D.; Fabre, C.; Gasnault, O.; Lanza, N.; Mazoyer, J.; Melikechi, N.; Meslin, P.-Y.; Newsom, H.; Ollila, A.; Perez, R.; Tokar, R.; Vaniman, D.

2013-01-01

The ChemCam instrument package on the Mars Science Laboratory rover, Curiosity, is the first planetary science instrument to employ laser-induced breakdown spectroscopy (LIBS) to determine the compositions of geological samples on another planet. Pre-processing of the spectra involves subtracting the ambient light background, removing noise, removing the electron continuum, calibrating for the wavelength, correcting for the variable distance to the target, and applying a wavelength-dependent correction for the instrument response. Further processing of the data uses multivariate and univariate comparisons with a LIBS spectral library developed prior to launch as well as comparisons with several on-board standards post-landing. The level-2 data products include semi-quantitative abundances derived from partial least squares regression. A LIBS spectral library was developed using 69 rock standards in the form of pressed powder disks, glasses, and ceramics to minimize heterogeneity on the scale of the observation (350–550 μm dia.). The standards covered typical compositional ranges of igneous materials and also included sulfates, carbonates, and phyllosilicates. The provenance and elemental and mineralogical compositions of these standards are described. Spectral characteristics of this data set are presented, including the size distribution and integrated irradiances of the plasmas, and a proxy for plasma temperature as a function of distance from the instrument. Two laboratory-based clones of ChemCam reside in Los Alamos and Toulouse for the purpose of adding new spectra to the database as the need arises. Sensitivity to differences in wavelength correlation to spectral channels and spectral resolution has been investigated, indicating that spectral registration needs to be within half a pixel and resolution needs to match within 1.5 to 2.6 pixels. Absolute errors are tabulated for derived compositions of each major element in each standard using PLS regression. Sources of errors are investigated and discussed, and methods for improving the analytical accuracy of compositions derived from ChemCam spectra are discussed.