Are preference and resistance to change convergent expressions of stimulus value?

PubMed

Podlesnik, Christopher A; Jimenez-Gomez, Corina; Shahan, Timothy A

2013-07-01

Behavioral momentum theory asserts that preference and relative resistance to disruption depend on reinforcement rates and provide converging expressions of the conditioned value of discriminative stimuli. However, preference and resistance to disruption diverge when assessing preference during brief extinction probes. We expanded upon this opposing relation by arranging target stimuli signaling equal variable-interval schedules across components of a multiple schedule. We paired one target stimulus with a richer reinforced alternative and the other with a leaner alternative. Furthermore, we varied reinforcement rates for the paired alternatives to assess the effects of manipulating relative conditioned value on preference and resistance to disruption by presession feeding, intercomponent food, and extinction. We replicated the opposing relation between preference and resistance to disruption but varying reinforcement rates for the paired alternatives did not systematically affect preference or resistance to disruption beyond levels observed in our initial condition. Importantly, we found that only preference between the target stimuli was related to relative baseline response rates in the presence of those stimuli. These findings suggest that preference during extinction probes might reveal more about baseline response rates between concurrently available alternatives than relative conditioned value. Resistance to disruption, conversely, appears to better reflect conditioned value because it is less confounded with baseline response rates and is a function of all sources of reinforcement obtained in the presence of a stimulus context. © Society for the Experimental Analysis of Behavior.

On-line vs off-line electrical conductivity characterization. Polycarbonate composites developed with multiwalled carbon nanotubes by compounding technology

NASA Astrophysics Data System (ADS)

Llorens-Chiralt, R.; Weiss, P.; Mikonsaari, I.

2014-05-01

Material characterization is one of the key steps when conductive polymers are developed. The dispersion of carbon nanotubes (CNTs) in a polymeric matrix using melt mixing influence final composite properties. The compounding becomes trial and error using a huge amount of materials, spending time and money to obtain competitive composites. Traditional methods to carry out electrical conductivity characterization include compression and injection molding. Both methods need extra equipments and moulds to obtain standard bars. This study aims to investigate the accuracy of the data obtained from absolute resistance recorded during the melt compounding, using an on-line setup developed by our group, and to correlate these values with off-line characterization and processing parameters (screw/barrel configuration, throughput, screw speed, temperature profile and CNTs percentage). Compounds developed with different percentages of multi walled carbon nanotubes (MWCNTs) and polycarbonate has been characterized during and after extrusion. Measurements, on-line resistance and off-line resistivity, showed parallel response and reproducibility, confirming method validity. The significance of the results obtained stems from the fact that we are able to measure on-line resistance and to change compounding parameters during production to achieve reference values reducing production/testing cost and ensuring material quality. Also, this method removes errors which can be found in test bars development, showing better correlation with compounding parameters.

Effect of unsaponifiable matter extracted from Pistacia khinjuk fruit oil on the oxidative stability of olive oil.

PubMed

Tavakoli, Javad; Estakhr, Parviz; Jelyani, Aniseh Zarei

2017-08-01

The present study was carried out to investigate the improvement of oxidative stability of refined olive oil using various concentrations of unsaponifiable matters extracted from Pistacia khinjuk fruit oil (UFO). For further elucidation of UFO antioxidative power, tertbutylhydroquinone (TBHQ) was used in an olive oil sample, too. Oxidative stability of olive oil samples without and with different levels of UFO (50, 100, 250, 500, 750 and 1000 ppm) and TBHQ (100 ppm) were studied via evaluation of conjugated diene value, carbonyl value, oil/oxidative stability index, acid value and total tocopherol (TT) contents through 8 h thermal process at 170 °C. Results obtained by oxidative stability assays revealed that the highest antioxidative activity of olive oil was obtained by 100 ppm of UFO, followed using 100, 250, 500, 750, and 1000 ppm of UFO and 100 ppm TBHQ, respectively. Evaluation of the relationship between oxidative stability indexes and TT changes indicated a strong correlation (R 2  = 0.9718) between mean relative resistance to oxidation and relative resistance to TT reduction during thermal process. By promotion of relative resistance to TT reduction, olive oil samples' relative resistance to oxidation was enhanced exponentially; implying importance of TT in promotion of oxidative stability of edible oils. The results obtained in this study showed that UFO has higher antioxidative activity compared to TBHQ; thus UFO can be considered as a natural antioxidant with ideal antioxidative activity.

Effect of EEG electrode density on dipole localization accuracy using two realistically shaped skull resistivity models.

PubMed

Laarne, P H; Tenhunen-Eskelinen, M L; Hyttinen, J K; Eskola, H J

2000-01-01

The effect of number of EEG electrodes on the dipole localization was studied by comparing the results obtained using the 10-20 and 10-10 electrode systems. Two anatomically detailed models with resistivity values of 177.6 omega m and 67.0 omega m for the skull were applied. Simulated potential values generated by current dipoles were applied to different combinations of the volume conductors and electrode systems. High and low resistivity models differed slightly in favour of the lower skull resistivity model when dipole localization was based on noiseless data. The localization errors were approximately three times larger using low resistivity model for generating the potentials, but applying high resistivity model for the inverse solution. The difference between the two electrode systems was minor in favour of the 10-10 electrode system when simulated, noiseless potentials were used. In the presence of noise the dipole localization algorithm operated more accurately using the denser electrode system. In conclusion, increasing the number of recording electrodes seems to improve the localization accuracy in the presence of noise. The absolute skull resistivity value also affects the accuracy, but using an incorrect value in modelling calculations seems to be the most serious source of error.

Comparison of power-plant condenser cooling-water fouling rates for spirally-indented and plain tubes

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

Rabas, T.; Panchal, C.; Sasscer, D.

1991-01-01

This paper presents the fouling rates for twelve TVA power-plant condensers, nine of which were retubed with an enhanced tube. The overall heat-transfer coefficients were calculated from logged field data taken over periods from one to ten years. The fouling resistances were calculated with the separate-resistance method and with a bundle correction factor to the condensing, single-tube Nusselt prediction. The fouling rates with the enhanced tubes ranged from about the same as to about twice that of the plain tubes. The thermal performance with the enhanced tubes remained superior to that obtained with plain-tubes for more than a year withoutmore » cleaning. After one year of operation, the enhanced-tube fouling resistance values were less than the minimum value of the TEMA Standards and the plain-tube fouling resistance values were always less than one half of this value. After shutdown cleaning, the thermal performance values for both tubes were restored to essentially the new, clean levels. 28 refs., 9 figs., 2 tabs.« less

Optimization of the parameters for obtaining zirconia-alumina coatings, made by flame spraying from results of numerical simulation

NASA Astrophysics Data System (ADS)

Ferrer, M.; Vargas, F.; Peña, G.

2017-12-01

The K-Sommerfeld values (K) and the melting percentage (% F) obtained by numerical simulation using the Jets et Poudres software were used to find the projection parameters of zirconia-alumina coatings by thermal spraying flame, in order to obtain coatings with good morphological and structural properties to be used as thermal insulation. The experimental results show the relationship between the Sommerfeld parameter and the porosity of the zirconia-alumina coatings. It is found that the lowest porosity is obtained when the K-Sommerfeld value is close to 45 with an oxidant flame, on the contrary, when superoxidant flames are used K values are close 52, which improve wear resistance.

Thermal inactivation of ileal loop-reactive Clostridium perfringens type A strains in phosphate buffer and beef gravy.

PubMed

Bradshaw, J G; Peeler, J T; Twedt, R M

1977-09-01

The thermal resistance of spore crops produced from each of two ileal loop-reactive strains of Clostridium perfringens type A was determined in two suspending vehicles consisting of 0.067 M (pH 7.0) phosphate buffer and a commercial beef gravy. D115.6 values obtained in buffer and enumerated after pretreatment with sodium ethylenediaminetetraacetate and recovery in plating medium containing lysozyme were two- to threefold greater than those obtained without this treatment. D115.6 values obtained with beef gravy were less than those obtained in buffer with or without lysozyme; however, the D98.9 and D104.4 values were 1.3 to 2 times greater than those obtained in buffer with lysozyme. The z values were within the ranges reported by previous investigators.

Thermal inactivation of ileal loop-reactive Clostridium perfringens type A strains in phosphate buffer and beef gravy.

PubMed Central

Bradshaw, J G; Peeler, J T; Twedt, R M

1977-01-01

The thermal resistance of spore crops produced from each of two ileal loop-reactive strains of Clostridium perfringens type A was determined in two suspending vehicles consisting of 0.067 M (pH 7.0) phosphate buffer and a commercial beef gravy. D115.6 values obtained in buffer and enumerated after pretreatment with sodium ethylenediaminetetraacetate and recovery in plating medium containing lysozyme were two- to threefold greater than those obtained without this treatment. D115.6 values obtained with beef gravy were less than those obtained in buffer with or without lysozyme; however, the D98.9 and D104.4 values were 1.3 to 2 times greater than those obtained in buffer with lysozyme. The z values were within the ranges reported by previous investigators. PMID:199113

Study on Correlation Between Shear Wave Velocity and Ground Properties for Ground Liquefaction Investigation of Silts

NASA Astrophysics Data System (ADS)

Che, Ailan; Luo, Xianqi; Qi, Jinghua; Wang, Deyong

Shear wave velocity (Vs) of soil is one of the key parameters used in assessment of liquefaction potential of saturated soils in the base with leveled ground surface; determination of shear module of soils used in seismic response analyses. Such parameter can be experimentally obtained from laboratory soil tests and field measurements. Statistical relation of shear wave velocity with soil properties based on the surface wave survey investigation, and resonant column triaxial tests, which are taken from more than 14 sites within the depth of 10 m under ground surface, is obtained in Tianjin (China) area. The relationship between shear wave velocity and the standard penetration test N value (SPT-N value) of silt and clay in the quaternary formation are summarized. It is an important problem to research the effect of shear wave velocity on liquefaction resistance of saturated silts (sandy loams) for evaluating liquefaction resistance. According the results of cyclic triaxial tests, a correlation between liquefaction resistance and shear wave velocity is presented. The results are useful for ground liquefaction investigation and the evaluation of liquefaction resistance.

Assessment of Mycosphaerella graminicola resistance to azoxystrobin.

PubMed

Siah, A; Deweer, C; Morand, E; Reignault, Ph; Halama, P

2008-01-01

Azoxystrobin resistance levels of twenty two strains sampled from ten French locations and two reference isolates (IPO323 and IPO94269) of the wheat pathogen Mycosphaerella graminicola were investigated in vitro. French strains assayed were selected from twenty two genetic groups determined from three hundred sixty three strains previously characterised using microsatellites, actine and beta-tubuline markers. For the first time, the evaluation was carried out using four distinct methods: spotting on PDA medium, spore germination on PDA medium and using microtitre plates with and without Alamar blue, a growth indicator. From dose-response curve, half maximal inhibitory concentration (IC50) was determined for each strain. The results obtained using microtitre plates with the addition of Alamar blue displayed high standard deviations from the growth averages observed. Therefore, we suggest that this method is inadequate to assess M. graminicolo resistance to fungicides. However, a good correlation was observed between the rankings of strains according to their IC50 values with the three other methods used. The two reference isolates, as expected, were inhibited by low azoxystrobin concentrations. On the other hand, the IC50 values obtained showed presence of a threshold between sensitive and resistant strains that corroborates the disruptive resistance of M. graminicola against strobilurin fungicides. In addition, the strains showing resistance were those sampled mainly from northern France, where a high frequency of strobilurin resistant isolates among M. graminicola populations was reported by several studies.

Resistance Potential of Bread Wheat Genotypes Against Yellow Rust Disease Under Egyptian Climate.

PubMed

Mahmoud, Amer F; Hassan, Mohamed I; Amein, Karam A

2015-12-01

Yellow rust (stripe rust), caused by Puccinia striiformis f. sp. tritici, is one of the most destructive foliar diseases of wheat in Egypt and worldwide. In order to identify wheat genotypes resistant to yellow rust and develop molecular markers associated with the resistance, fifty F8 recombinant inbred lines (RILs) derived from a cross between resistant and susceptible bread wheat landraces were obtained. Artificial infection of Puccinia striiformis was performed under greenhouse conditions during two growing seasons and relative resistance index (RRI) was calculated. Two Egyptian bread wheat cultivars i.e. Giza-168 (resistant) and Sakha-69 (susceptible) were also evaluated. RRI values of two-year trial showed that 10 RILs responded with RRI value >6 <9 with an average of 7.29, which exceeded the Egyptian bread wheat cultivar Giza-168 (5.58). Thirty three RILs were included among the acceptable range having RRI value >2 <6. However, only 7 RILs showed RRI value <2. Five RILs expressed hypersensitive type of resistance (R) against the pathogen and showed the lowest Average Coefficient of Infection (ACI). Bulked segregant analysis (BSA) with eight simple sequence repeat (SSR), eight sequence-related amplified polymorphism (SRAP) and sixteen random amplified polymorphic DNA (RAPD) markers revealed that three SSR, three SRAP and six RAPD markers were found to be associated with the resistance to yellow rust. However, further molecular analyses would be performed to confirm markers associated with the resistance and suitable for marker-assisted selection. Resistant RILs identified in the study could be efficiently used to improve the resistance to yellow rust in wheat.

Time Domain Estimation of Arterial Parameters using the Windkessel Model and the Monte Carlo Method

NASA Astrophysics Data System (ADS)

Gostuski, Vladimir; Pastore, Ignacio; Rodriguez Palacios, Gaspar; Vaca Diez, Gustavo; Moscoso-Vasquez, H. Marcela; Risk, Marcelo

2016-04-01

Numerous parameter estimation techniques exist for characterizing the arterial system using electrical circuit analogs. However, they are often limited by their requirements and usually high computational burdain. Therefore, a new method for estimating arterial parameters based on Monte Carlo simulation is proposed. A three element Windkessel model was used to represent the arterial system. The approach was to reduce the error between the calculated and physiological aortic pressure by randomly generating arterial parameter values, while keeping constant the arterial resistance. This last value was obtained for each subject using the arterial flow, and was a necessary consideration in order to obtain a unique set of values for the arterial compliance and peripheral resistance. The estimation technique was applied to in vivo data containing steady beats in mongrel dogs, and it reliably estimated Windkessel arterial parameters. Further, this method appears to be computationally efficient for on-line time-domain estimation of these parameters.

Wear resistance of Polymethyl Methacrylate (PMMA) with the Addition of Bone Ash, Hydroxylapatite and Keratin

NASA Astrophysics Data System (ADS)

Emre, G.; Akkus, A.; Karamış, M. B.

2018-01-01

In this study mechanichal and tribological properties of keratin, bone ash and hydroxylapatite by adding to PMMA ( known as the main prosthesis material) were investigated. Hydroxylapatite, bone ash, and keratin materials were added as PMMA in to the content of PMMA, in the proportions of %1, %3 and %5, respectively. The resulting mixtures were put into the molds and solidified in order to obtain samples to be used in the wear experiments. Each experiment was conducted by preparing three experimental samples. The wear data were compared according to the average values of the experimental samples. In the wear test, the results were also evaluated according to the average values obtained from each group and the results of the control group. It was observed that, the wear resistance of the PMMA including 3%, 5% bone ash and PMMA including 5% keratin flour were higher than the values of the control group.

Antimicrobial Susceptibility of Bordetella bronchiseptica Isolates from Swine and Companion Animals and Detection of Resistance Genes.

PubMed

Prüller, Sandra; Rensch, Ulrike; Meemken, Diana; Kaspar, Heike; Kopp, Peter A; Klein, Günter; Kehrenberg, Corinna

2015-01-01

Bordetella bronchiseptica causes infections of the respiratory tract in swine and other mammals and is a precursor for secondary infections with Pasteurella multocida. Treatment of B. bronchiseptica infections is conducted primarily with antimicrobial agents. Therefore it is essential to get an overview of the susceptibility status of these bacteria. The aim of this study was to comparatively analyse broth microdilution susceptibility testing according to CLSI recommendations with an incubation time of 16 to 20 hours and a longer incubation time of 24 hours, as recently proposed to obtain more homogenous MICs. Susceptibility testing against a panel of 22 antimicrobial agents and two fixed combinations was performed with 107 porcine isolates from different farms and regions in Germany and 43 isolates obtained from companion animals in Germany and other European countries. Isolates with increased MICs were investigated by PCR assays for the presence of resistance genes. For ampicillin, all 107 porcine isolates were classified as resistant, whereas only a single isolate was resistant to florfenicol. All isolates obtained from companion animals showed elevated MICs for β-lactam antibiotics and demonstrated an overall low susceptibility to cephalosporines. Extension of the incubation time resulted in 1-2 dilution steps higher MIC50 values of porcine isolates for seven antimicrobial agents tested, while isolates from companion animals exhibited twofold higher MIC50/90 values only for tetracycline and cefotaxime. For three antimicrobial agents, lower MIC50 and MIC90 values were detected for both, porcine and companion animal isolates. Among the 150 isolates tested, the resistance genes blaBOR-1 (n = 147), blaOXA-2, (n = 4), strA and strB (n = 17), sul1 (n = 10), sul2 (n = 73), dfrA7 (n = 3) and tet(A) (n = 8) were detected and a plasmid localisation was identified for several of the resistance genes.

Antimicrobial Susceptibility of Bordetella bronchiseptica Isolates from Swine and Companion Animals and Detection of Resistance Genes

PubMed Central

Prüller, Sandra; Rensch, Ulrike; Meemken, Diana; Kaspar, Heike; Kopp, Peter A.; Klein, Günter; Kehrenberg, Corinna

2015-01-01

Bordetella bronchiseptica causes infections of the respiratory tract in swine and other mammals and is a precursor for secondary infections with Pasteurella multocida. Treatment of B. bronchiseptica infections is conducted primarily with antimicrobial agents. Therefore it is essential to get an overview of the susceptibility status of these bacteria. The aim of this study was to comparatively analyse broth microdilution susceptibility testing according to CLSI recommendations with an incubation time of 16 to 20 hours and a longer incubation time of 24 hours, as recently proposed to obtain more homogenous MICs. Susceptibility testing against a panel of 22 antimicrobial agents and two fixed combinations was performed with 107 porcine isolates from different farms and regions in Germany and 43 isolates obtained from companion animals in Germany and other European countries. Isolates with increased MICs were investigated by PCR assays for the presence of resistance genes. For ampicillin, all 107 porcine isolates were classified as resistant, whereas only a single isolate was resistant to florfenicol. All isolates obtained from companion animals showed elevated MICs for β-lactam antibiotics and demonstrated an overall low susceptibility to cephalosporines. Extension of the incubation time resulted in 1–2 dilution steps higher MIC50 values of porcine isolates for seven antimicrobial agents tested, while isolates from companion animals exhibited twofold higher MIC50/90 values only for tetracycline and cefotaxime. For three antimicrobial agents, lower MIC50 and MIC90 values were detected for both, porcine and companion animal isolates. Among the 150 isolates tested, the resistance genes bla BOR-1 (n = 147), bla OXA-2, (n = 4), strA and strB (n = 17), sul1 (n = 10), sul2 (n = 73), dfrA7 (n = 3) and tet(A) (n = 8) were detected and a plasmid localisation was identified for several of the resistance genes. PMID:26275219

Temperature and volumetric water content petrophysical relationships in municipal solid waste for the interpretation of bulk electrical resistivity data

NASA Astrophysics Data System (ADS)

Pilawski, Tamara; Dumont, Gaël; Nguyen, Frédéric

2015-04-01

Landfills pose major environmental issues including long-term methane emissions, and local pollution of soil and aquifers but can also be seen as potential energy resources and mining opportunities. Water content in landfills determine whether solid fractions can be separated and recycled, and controls the existence and efficiency of natural or enhanced biodegradation. Geophysical techniques, such as electrical and electromagnetic methods have proven successful in the detection and qualitative investigation of sanitary landfills. However, their interpretation in terms of quantitative water content estimates makes it more challenging due to the influence of parameters such as temperature, compaction, waste composition or pore fluid. To improve the confidence given to bulk electrical resistivity data and to their interpretation, we established temperature and volumetric water content petrophysical relationships that we tested on field and laboratory electrical resistivity measurements. We carried out two laboratory experiments on leachates and waste samples from a landfill located in Mont-Saint-Guibert, Belgium. We determined a first relationship between temperature and electrical resistivity with pure and diluted leachates by progressively increasing the temperature from 5°C to 65°C, and then cooling down to 5°C. The second relationship was obtained by measuring electrical resistivity on waste samples of different volumetric water contents. First, we used the correlations obtained from the experiments to compare electrical resistivity measurements performed in a landfill borehole and on reworked waste samples excavated at different depths. Electrical resistivities were measured every 20cm with an electromagnetic logging device (EM39) while a temperature profile was acquired with optic fibres. Waste samples were excavated every 2m in the same borehole. We filled experimental columns with these samples and measured electrical resistivities at laboratory temperature. We made corrections according to the temperature profile and to volumetric water contents obtained previously on undisturbed samples. Corrected values tended to be superimposed on those obtained in the field. Then, we calculated the water content of the different reworked waste samples using the correlation between volumetric water content correlation and electrical resistivity and we compared this value to the one measured at the laboratory. Both values were correlated satisfactorily. In conclusion, we show that bulk electrical resistivity measurements are very promising to quantify water content in landfills if temperature can be estimated independently. In future applications, electrical resistivity tomography coupled with distributed temperature sensing could give important estimates of water content of the waste and thus helping in dealing with problematics such as boosting biodegradation and stabilization of the waste, reducing risks of soil and aquifers pollution, landfill mining, and controlled production of methane.

Determination of Soil Moisture Content using Laboratory Experimental and Field Electrical Resistivity Values

NASA Astrophysics Data System (ADS)

Hazreek, Z. A. M.; Rosli, S.; Fauziah, A.; Wijeyesekera, D. C.; Ashraf, M. I. M.; Faizal, T. B. M.; Kamarudin, A. F.; Rais, Y.; Dan, M. F. Md; Azhar, A. T. S.; Hafiz, Z. M.

2018-04-01

The efficiency of civil engineering structure require comprehensive geotechnical data obtained from site investigation. In the past, conventional site investigation was heavily related to drilling techniques thus suffer from several limitations such as time consuming, expensive and limited data collection. Consequently, this study presents determination of soil moisture content using laboratory experimental and field electrical resistivity values (ERV). Field and laboratory electrical resistivity (ER) test were performed using ABEM SAS4000 and Nilsson400 soil resistance meter. Soil sample used for resistivity test was tested for characterization test specifically on particle size distribution and moisture content test according to BS1377 (1990). Field ER data was processed using RES2DINV software while laboratory ER data was analyzed using SPSS and Excel software. Correlation of ERV and moisture content shows some medium relationship due to its r = 0.506. Moreover, coefficient of determination, R2 analyzed has demonstrate that the statistical correlation obtain was very good due to its R2 value of 0.9382. In order to determine soil moisture content based on statistical correlation (w = 110.68ρ-0.347), correction factor, C was established through laboratory and field ERV given as 19.27. Finally, this study has shown that soil basic geotechnical properties with particular reference to water content was applicably determined using integration of laboratory and field ERV data analysis thus able to compliment conventional approach due to its economic, fast and wider data coverage.

Mechanical and Microstructural Characterization of a New Corrosion Resistant Stainless Steel

NASA Astrophysics Data System (ADS)

Voiculescu, I.; Geantă, V.; Stefănoiu, R.; Cotruţ, C.; Ciocoiu, R.; Ionescu, M.

2018-06-01

The paper investigates the manner in which the chemical composition and delivery status of a new type of stainless steel, highly alloyed with Ni and Cr, affect mechanical properties, microstructure and corrosion resistance. The results obtained during the mechanical test (tensile, compression, Charpy test and micro-hardness) have revealed promising values. During the corrosion test, the preferential attack of the reagent (Aqua regia) located on the grain boundaries, inclusions or polyhedral precipitates have been observed. On the corroded surfaces, some localized pitting effects on grain boundaries have been revealed. The analyses of the parameter values recorded during the corrosion test revealed that the corrosion current density had a low value, comparable to that of other specific types of stainless steels. The actual Icorr (1.089 µA/cm2) value measured for the experimental alloy proves good resistance to corrosion in 3% NaCl saline solution. The estimated rate of corrosion presented acceptable values (0.011 mm/year).

Laboratory Study of Quaternary Sediment Resistivity Related to Groundwater Contamination at Mae-Hia Landfill, Mueang District, Chiang Mai Province

NASA Astrophysics Data System (ADS)

Sichan, N.

2007-12-01

This study was aimed to understand the nature of the resistivity value of the sediment when it is contaminated, in order to use the information solving the obscure interpretation in the field. The pilot laboratory experiments were designed to simulate various degree of contamination and degree of saturation then observe the resulting changes in resistivity. The study was expected to get a better understanding of how various physical parameters effect the resistivity values in term of mathematic function. And also expected to apply those obtained function to a practical quantitatively interpretation. The sediment underlying the Mae-Hia Landfill consists of clay-rich material, with interfingerings of colluvium and sandy alluvium. A systematic study identified four kinds of sediment, sand, clayey sand, sandy clay, and clay. Representative sediment and leachate samples were taken from the field and returned to the laboratory. Both the physical and chemical properties of the sediments and leachate were analyzed to delineate the necessary parameters that could be used in Archie's equation. Sediment samples were mixed with various concentration of leachate solutions. Then the resistivity values were measured at various controlled steps in the saturation degree in a well- calibrated six-electrode model resistivity box. The measured resistivity values for sand, clayey sand, sandy clay when fully and partly saturated were collected, then plotted and fitted to Archie's equation, to obtain a mathematical relationship between bulk resistivity, porosity, saturation degree and resistivity of pore fluid. The results fit well to Archie's equation, and it was possible to determine all the unknown parameters representative of the sediment samples. For sand, clayey sand, sandy clay, and clay, the formation resistivity factors (F) are 2.90, 5.77, 7.85, and 7.85 with the products of cementation factor (m) and the pore geometry factors (a) (in term of -am) are 1.49, -1.63, -1.92, -2.24 and the saturation exponents (n) are 2.06, 2.58, 3.52, and 2.46, respectively. These results were used to reinterpret the existing resistivity data of this area. The result of this reinterpretation is a map showing the quantitative distribution of the contaminant plume in the vicinity of the Mae-Hia Landfill.

The role of the microfissuration of the rock matrix in the abrasion resistance of ornamental granitic rocks

NASA Astrophysics Data System (ADS)

Rodríguez-Rey, Angel; Sanchez-Delgado, Nuria; Camino, Clara; Calleja, Lope; Ruiz de Argandoña, Vicente G.; Setien, Alexia

2015-04-01

The microcrack density and the abrasion resistance of five ornamental granites (Albero, Gris Alba, Mondariz, Rosa Porriño and Traspieles) from Galicia (NW Spain) have been quantified as part of a research aimed to interpret the cuttability of the rocks in relation to the petrophysical properties of the rock matrix. Large blocks from the quarries have been cut with an industrial saw and the microcrack density and the abrasion resistance have been measured in two surfaces: H, parallel to the cut surface; T, perpendicular both to the cut surface and the cutting direction. Both planes are perpendicular to the rift plane, as it is known in quarry works. The microcrack density has been quantified following an stereological procedure applied to polished sections imaged under scanning electron microscopy. The magnification of the images allowed the study of microcracks as narrow as 2 microns in aperture. The density has been quantified in terms of length of microcrack traces per surface unit so possible anisotropies of the microcrack network could be detected. The obtained values are in the typical range for this type of rocks although the Traspieles granite shows a higher value due to its weathering degree (H: 5.11, T: 5.37 mm/mm2). The values measured in the two surfaces (H and T) are quite similar in four of the rocks; only the Albero granite shows a marked anisotropy (H: 2.76 T: 3.53 mm/mm2). The abrasion resistance of the rocks has been measured following the european standard EN 14157:2004 using the capon method. The rocks can be classified in two groups according to their abrasion resistance. Rosa Porriño, Gris Alba and Mondariz granites are the more resistant to abrasion with values around 16-17 mm. Albero and Traspieles granites are less resistant with values higher than 19 mm. The results show a good correlation between the microcrack density and the abrasion resistance. As can be expected the rocks with high microcrack density show low abrasion resistance. The coefficient of determination, R2, obtained with the values of the H surface is 0.67 and the coefficient corresponding to the T surface is higher, 0.81. Acknowledgements This research has been funded by the "Direccion General de Investigacion Cientifica y Tecnica del Ministerio de Economia y Competitividad" (Spain). (Project MINECO-13-CGL2012-33588)

Low resistance contacts for shallow junction semiconductors

NASA Technical Reports Server (NTRS)

Fatemi, Navid S. (Inventor); Weizer, Victor G. (Inventor)

1994-01-01

A method of enhancing the specific contact resistivity in InP semiconductor devices and improved devices produced thereby are disclosed. Low resistivity values are obtained by using gold ohmic contacts that contain small amounts of gallium or indium and by depositing a thin gold phosphide interlayer between the surface of the InP device and the ohmic contact. When both the thin interlayer and the gold-gallium or gold-indium contact metallizations are used, ultra low specific contact resistivities are achieved. Thermal stability with good contact resistivity is achieved by depositing a layer of refractory metal over the gold phosphide interlayer.

The slip resistance of common footwear materials measured with two slipmeters.

PubMed

Chang, W R; Matz, S

2001-12-01

The slip resistance of 16 commonly used footwear materials was measured with the Brungraber Mark II and the English XL on 3 floor surfaces under surface conditions of dry, wet, oily and oily wet. Three samples were used for each material combination and surface condition. The results of a one way ANOVA analysis indicated that the differences among different samples were statistically significant for a large number of material combinations and surface conditions. The results indicated that the ranking of materials based on their slip resistance values depends highly on the slipmeters, floor surfaces and surface conditions. For contaminated surfaces including wet, oily and oily wet surfaces, the slip resistance obtained with the English XL was usually higher than that measured with the Brungraber Mark II. The correlation coefficients between the slip resistance obtained with these two slipmeters calculated for different surface conditions indicated a strong correlation with statistical significance.

Thermal resistance of Listeria monocytogenes in sausage meat.

PubMed

Farber, J M; Hughes, A; Holley, R; Brown, B

1989-01-01

The heat resistance of a mixture of 10 different strains of Listeria monocytogenes inoculated into ground meat and ground meat plus cure was examined. D-values for ground meat ranged from 1.01 min at 62 degrees C to 13.18 min at 56 degrees C. The D-values obtained for ground meat plus cure were approximately 5-8 fold times higher than those for ground meat alone. These results imply that rare meats and possibly some cooked fermented meats may not be heated adequately to inactivate Listeria.

Corrosion resistant metallic glasses for biosensing applications

NASA Astrophysics Data System (ADS)

Sagasti, Ariane; Lopes, Ana Catarina; Lasheras, Andoni; Palomares, Verónica; Carrizo, Javier; Gutierrez, Jon; Barandiaran, J. Manuel

2018-04-01

We report the fabrication by melt spinning, the magnetic and magnetoelastic characterization and corrosion behaviour study (by potentiodynamic methods) of an Fe-based, Fe-Ni-Cr-Si-B metallic glass to be used as resonant platform for biological and chemical detection purposes. The same study has been performed in Fe-Co-Si-B (with excellent magnetoelastic properties) and Fe-Ni-B (with good corrosion properties due to the substitution of Co by Ni) composition amorphous alloys. The well-known, commercial metallic glass with high corrosion resistance Metglas 2826MB®(Fe40Ni38Mo4B18), widely used for such biological and chemical detection purposes, has been also fully characterized and used as reference. For our Fe-Ni-Cr-Si-B alloy, we have measured values of magnetization (1.22 T), magnetostriction (11.5 ppm) and ΔE effect (6.8 %) values, as well as corrosion potential (-0.25 V), current density (2.54 A/m2), and polarization resistance (56.22 Ω.cm2) that make this composition very promising for the desired biosensing applications. The obtained parameters from our exhaustive characterization are compared with the values obtained for the other different composition metallic glasses and discussed in terms of Ni and Cr content.

Electro-thermal analysis of contact resistance

NASA Astrophysics Data System (ADS)

Pandey, Nitin; Jain, Ishant; Reddy, Sudhakar; Gulhane, Nitin P.

2018-05-01

Electro-Mechanical characterization over copper samples are performed at the macroscopic level to understand the dependence of electrical contact resistance and temperature on surface roughness and contact pressure. For two different surface roughness levels of samples, six levels of load are selected and varied to capture the bulk temperature rise and electrical contact resistance. Accordingly, the copper samples are modelled and analysed using COMSOLTM as a simulation package and the results are validated by the experiments. The interface temperature during simulation is obtained using Mikic-Elastic correlation and by directly entering experimental contact resistance value. The load values are varied and then reversed in a similar fashion to capture the hysteresis losses. The governing equations & assumptions underlying these models and their significance are examined & possible justification for the observed variations are discussed. Equivalent Greenwood model is also predicted by mapping the results of the experiment.

The achievement of low contact resistance to indium phosphide: The roles of Ni, Au, Ge, and combinations thereof

NASA Technical Reports Server (NTRS)

Fatemi, Navid S.; Weizer, Victor G.

1992-01-01

We have investigated the electrical and metallurgical behavior of Ni, Au-Ni, and Au-Ge-Ni contacts on n-InP. We have found that very low values of contact resistivity rho(sub c) in the E-7 omega-sq cm range are obtained with Ni-only contacts. We show that the addition of Au to Ni contact metallization effects an additional order of magnitude reduction in rho(sub c). Ultra-low contact resistivities in the E-8 omega-sq cm range are obtained with both the Au-Ni and the Au-Ge-Ni systems, effectively eliminating the need for the presence of Ge in the Au-Ge-Ni system. The formation of various nickel phosphides at the metal-InP interface is shown to be responsible for the observed rho(sub c) values in the Ni and Au-Ni systems. We show, finally, that the order in which the constituents of Au-Ni and Au-Ge-Ni contacts are deposited has a significant bearing on the composition of the reaction products formed at the metal-InP interface and therefore on the contact resistivity at that interface.

Thermal inactivation kinetics of Bacillus coagulans spores in tomato juice.

PubMed

Peng, Jing; Mah, Jae-Hyung; Somavat, Romel; Mohamed, Hussein; Sastry, Sudhir; Tang, Juming

2012-07-01

The thermal characteristics of the spores and vegetative cells of three strains of Bacillus coagulans (ATCC 8038, ATCC 7050, and 185A) in tomato juice were evaluated. B. coagulans ATCC 8038 was chosen as the target microorganism for thermal processing of tomato products due to its spores having the highest thermal resistance among the three strains. The thermal inactivation kinetics of B. coagulans ATCC 8038 spores in tomato juice between 95 and 115°C were determined independently in two different laboratories using two different heating setups. The results obtained from both laboratories were in general agreement, with z-values (z-value is defined as the change in temperature required for a 10-fold reduction of the D-value, which is defined as the time required at a certain temperature for a 1-log reduction of the target microorganisms) of 8.3 and 8.7°C, respectively. The z-value of B. coagulans 185A spores in tomato juice (pH 4.3) was found to be 10.2°C. The influence of environmental factors, including cold storage time, pH, and preconditioning, upon the thermal resistance of these bacterial spores is discussed. The results obtained showed that a storage temperature of 4°C was appropriate for maintaining the viability and thermal resistance of B. coagulans ATCC 8038 spores. Acidifying the pH of tomato juice decreased the thermal resistance of these spores. A 1-h exposure at room temperature was considered optimal for preconditioning B. coagulans ATCC 8038 spores in tomato juice.

Flow cytometry as a rapid test for detection of penicillin resistance directly in bacterial cells in Enterococcus faecalis and Staphylococcus aureus.

PubMed

Jarzembowski, T; Wiśniewska, K; Józwik, A; Bryl, E; Witkowski, J

2008-08-01

We studied the usefulness of flow cytometry for detection of penicillin resistance in E. faecalis and S. aureus by direct binding of commercially available fluorescent penicillin, Bocillin FL, to cells obtained from culture. There were significantly lower percentages of fluorescent cells and median and mean fluorescence values per particle in penicillin-resistant than in penicillin-sensitive strains of both species observed. The method allows rapid detection of penicillin resistance in S. aureus and E. faecalis. The results encourage further investigations on the detection of antibiotic resistance in bacteria using flow cytometry.

New method of extrapolation of the resistance of a model planing boat to full size

NASA Technical Reports Server (NTRS)

Sottorf, W

1942-01-01

The previously employed method of extrapolating the total resistance to full size with lambda(exp 3) (model scale) and thereby foregoing a separate appraisal of the frictional resistance, was permissible for large models and floats of normal size. But faced with the ever increasing size of aircraft a reexamination of the problem of extrapolation to full size is called for. A method is described by means of which, on the basis of an analysis of tests on planing surfaces, the variation of the wetted surface over the take-off range is analytically obtained. The friction coefficients are read from Prandtl's curve for turbulent boundary layer with laminar approach. With these two values a correction for friction is obtainable.

The structure and physical-mechanical properties of the heat-resistant Ni-Co-Cr-Al-Y intermetallic coating obtained using rebuilt plasma equipment

NASA Astrophysics Data System (ADS)

Tarasenko, Yu. P.; Tsareva, I. N.; Berdnik, O. B.; Fel, Ya. A.; Kuzmin, V. I.; Mikhalchenko, A. A.; Kartaev, E. V.

2014-12-01

Results of a study of the structure, physico-mechanical properties, and the resistance to heat of Ni-Co-Cr-Al-Y intermetallic coatings obtained by powder spraying on the standard UPU-3D plasma spray facility (plasmatron with self-establishing arc length) and on the rebuilt facility equipped with the enhanced-power PNK-50 plasmatron with sectionalized inter-electrode insert, are reported. Coatings of higher density ( ρ = 7.9 g/cm3) and higher microhardness (H μ = 770 kg-force/mm2) with lower porosity values ( P = 5.7 %, P c = 5.1 %, and P 0 = 0.6 %) and high resistance to heat ((M - M0)/M0 = 1.2) were obtained. The developed coating is intended for protection of the working surfaces of turbine engine blades in gas-turbine power plants.

ELECTRIC IMPEDANCE OF THE FROG EGG

PubMed Central

Cole, Kenneth S.; Guttman, Rita M.

1942-01-01

Electrical impedance measurements were made upon unfertilized and fertilized eggs of the leopard frog, Rana pipiens, over a frequency range of 0.05 to 10 kc. Average values of 170 ohm cm.2 were obtained for the plasma membrane resistance of the egg, 2.0 µf/cm.2 for the plasma membrane capacity, 86° for the phase angle of the membrane, and 570 ohm cm. for the specific resistance of the interior. These values did not change upon fertilization. No spontaneous rhythmical impedance changes such as have been found by Hubbard and Rothschild in the trout egg were found in frog eggs. PMID:19873312

Research of vibration control based on current mode piezoelectric shunt damping circuit

NASA Astrophysics Data System (ADS)

Liu, Weiwei; Mao, Qibo

2017-12-01

The piezoelectric shunt damping circuit using current mode approach is imposed to control the vibration of a cantilever beam. Firstly, the simulated inductance with large values are designed for the corresponding RL series shunt circuits. Moreover, with an example of cantilever beam, the second natural frequency of the beam is targeted to control for experiment. By adjusting the values of the equivalent inductance and equivalent resistance of the shunt circuit, the optimal damping of the shunt circuit is obtained. Meanwhile, the designed piezoelectric shunt damping circuit stability is experimental verified. Experimental results show that the proposed piezoelectric shunt damping circuit based on current mode circuit has good vibration control performance. However, the control performance will be reduced if equivalent inductance and equivalent resistance values deviate from optimal values.

In-situ measurement system

DOEpatents

Lord, David E.

1983-01-01

A multipurpose in situ underground measurement system comprising a plurality of long electrical resistance elements in the form of rigid reinforcing bars, each having an open loop "hairpin" configuration of shorter length than the other resistance elements. The resistance elements are arranged in pairs in a unitized structure, and grouted in place in the underground volume. The electrical resistance of each element and the difference in electrical resistance of the paired elements are obtained, which difference values may be used in analytical methods involving resistance as a function of temperature. A scanner sequentially connects the resistance-measuring apparatus to each individual pair of elements. A source of heating current is also selectively connectable for heating the elements to an initial predetermined temperature prior to electrical resistance measurements when used as an anemometer.

Concretes of low environmental impact obtained by geopolymerization of Metakaolin

NASA Astrophysics Data System (ADS)

Sandoval, D. C.; Montaño, A. M.; González, C. P.; Gutiérrez, J.

2018-04-01

This work shows results of partial replacement of Portland Type I cement®, by geopolymers obtained through alkaline activation of Metakaolin, in concrete mixtures. Replacement was made with 10%, 20% and 30% of geopolymers at 7, 14, 28 and 90 days of setting. Cement samples was mechanical and electrically tested. Mechanical resistance to compression assay shows that the best percentage of replacement is 10% for every setting time; highest value is 26.75MPa at 90 days. Nyquist diagrams at different times of immersion exhibit same trend: decreasing of electrical resistance as time of assay goes by.

Glucono-delta-lactone and citric acid as acidulants for lowering the heat resistance of Clostridium sporogenes PA 3679 in HTST working conditions.

PubMed

Silla Santos, M H; Torres Zarzo, J

1995-04-01

The heat resistance of Clostridium sporogenes PA 3679 spores has been studied to establish the influence of acidification with glucono-delta-lactone (GDL) and citric acid on the thermal resistance parameters (DT and z) of this microorganism and to compare their effect with phosphate buffer and natural asparagus as reference substrates. A reduction in DT values was observed in asparagus purée as the acidification level increased with both acidulants although this effect was more evident at the lower treatment temperatures studied (121-127 degrees C). Citric acid was more effective for reducing the heat resistance of spores than GDL at all of the temperatures. The reduction in pH diminished the value of the z parameter, although it was necessary to lower the pH to 4.5 to obtain a significant reduction.

Significance of resistive index in color Doppler ultrasonogram: differentiation between benign and malignant breast masses.

PubMed

Choi, H Y; Kim, H Y; Baek, S Y; Kang, B C; Lee, S W

1999-01-01

The objective of this article is to evaluate the significance of resistive index in differentiation between benign and malignant breast lesions on duplex ultrasonographic examination. Resistive indices obtained in 106 breast lesions of 104 patients were included. Sixty-four were benign (mean age: 32.4 +/- 11.1 years), and 42 were malignant lesions (mean age: 47.8 +/- 11.4 years). The resistive index was classified as follows: below 0.49, from 0.5 to 0.59, 0.6 to 0.69, 0.7 to 0.79, and above 0.8. We analyzed and defined the optimal threshold value of RI between benign and malignant lesions. The mean values of the RI of benign and malignant lesions were 0.62 +/- 0.095 (range 0.44-0.86) and 0.74 +/- 0.097 (range, 0.50-0.92), respectively. The resistive index exceeded 0.7 in 80% of malignant lesions. The difference of the RI between malignant and benign lesions was statistically significant when the threshold value was 0.7 (P < 0.001). A resistive index over 0.7 may suggest malignant lesions. Due to the considerable overlap of the range of the RI, it may not be diagnostic in any single patient; however, it may be helpful in conjunct with gray-scale image.

Direct comparison of fractional and integer quantized Hall resistance

NASA Astrophysics Data System (ADS)

Ahlers, Franz J.; Götz, Martin; Pierz, Klaus

2017-08-01

We present precision measurements of the fractional quantized Hall effect, where the quantized resistance {{R}≤ft[ 1/3 \\right]} in the fractional quantum Hall state at filling factor 1/3 was compared with a quantized resistance {{R}[2]} , represented by an integer quantum Hall state at filling factor 2. A cryogenic current comparator bridge capable of currents down to the nanoampere range was used to directly compare two resistance values of two GaAs-based devices located in two cryostats. A value of 1-(5.3  ±  6.3) 10-8 (95% confidence level) was obtained for the ratio ({{R}≤ft[ 1/3 \\right]}/6{{R}[2]} ). This constitutes the most precise comparison of integer resistance quantization (in terms of h/e 2) in single-particle systems and of fractional quantization in fractionally charged quasi-particle systems. While not relevant for practical metrology, such a test of the validity of the underlying physics is of significance in the context of the upcoming revision of the SI.

The in vitro effects of retrograded starch (resistant starch type 3) from lotus seed starch on the proliferation of Bifidobacterium adolescentis.

PubMed

Zhang, Yi; Wang, Ying; Zheng, Baodong; Lu, Xu; Zhuang, Weijing

2013-11-01

Prebiotics such as oligosaccharides, fructans, and resistant starch (RS) stimulate the growth of beneficial bacteria in large bowel and modify the human gastrointestinal environment. In this study, compared with glucose (GLU) and high amylose maize starch (HAMS), the in vitro effects of LRS3 and P-LRS3 (RS3 and purified RS3 prepared from lotus seed starch) on the proliferation of bifidobacteria were assessed by assessing the changes in optical density (OD), pH values, short chain fatty acid (SCFA) production, and tolerance ability to gastrointestinal conditions. Significantly higher OD values were obtained from media containing LRS3 and P-LRS3, and especially in the medium containing P-LRS3, the OD value of which reached 1.36 when the concentration of the carbon source was 20 g L(-1). Additionally, the lag phase of bifidobacteria was 8 h in the medium with LRS3 or P-LRS3, whereas it was 16 h in the medium with GLU or HAMS. What is more, a higher content of butyric acid was obtained in the P-LRS3 medium. Compared with GLU and HAMS media, bifidobacteria had a higher tolerance to gastrointestinal conditions in LRS3 and P-LRS3 media. It shows that lotus seed resistant starch, especially P-LRS3, could stimulate the growth of bifidobacteria. The rough surface of resistant starch and the SCFAs produced during fermentation might influence the proliferation of bifidobacteria.

Laser Powder Cladding of Ti-6Al-4V α/β Alloy

PubMed Central

Al-Sayed Ali, Samar Reda; Hussein, Abdel Hamid Ahmed; Nofal, Adel Abdel Menam Saleh; Elgazzar, Haytham Abdelrafea; Sabour, Hassan Abdel

2017-01-01

Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD). The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm−2. An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times. PMID:29036935

Laser Powder Cladding of Ti-6Al-4V α/β Alloy.

PubMed

Al-Sayed Ali, Samar Reda; Hussein, Abdel Hamid Ahmed; Nofal, Adel Abdel Menam Saleh; Hasseb Elnaby, Salah Elden Ibrahim; Elgazzar, Haytham Abdelrafea; Sabour, Hassan Abdel

2017-10-15

Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD). The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm -2 . An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times.

Theoretical relationship between elastic wave velocity and electrical resistivity

NASA Astrophysics Data System (ADS)

Lee, Jong-Sub; Yoon, Hyung-Koo

2015-05-01

Elastic wave velocity and electrical resistivity have been commonly applied to estimate stratum structures and obtain subsurface soil design parameters. Both elastic wave velocity and electrical resistivity are related to the void ratio; the objective of this study is therefore to suggest a theoretical relationship between the two physical parameters. Gassmann theory and Archie's equation are applied to propose a new theoretical equation, which relates the compressional wave velocity to shear wave velocity and electrical resistivity. The piezo disk element (PDE) and bender element (BE) are used to measure the compressional and shear wave velocities, respectively. In addition, the electrical resistivity is obtained by using the electrical resistivity probe (ERP). The elastic wave velocity and electrical resistivity are recorded in several types of soils including sand, silty sand, silty clay, silt, and clay-sand mixture. The appropriate input parameters are determined based on the error norm in order to increase the reliability of the proposed relationship. The predicted compressional wave velocities from the shear wave velocity and electrical resistivity are similar to the measured compressional velocities. This study demonstrates that the new theoretical relationship may be effectively used to predict the unknown geophysical property from the measured values.

Wear and corrosion resistance of electroforming layer after WEDM for 7075 aluminum alloy

NASA Astrophysics Data System (ADS)

Xu, Jinkai; Qiu, Rongxian; Lian, Zhongxu; Yu, Zhanjiang; Yu, Peng; Ren, Wanfei; Yu, Huadong

2018-06-01

In order to investigate the influence of the recast layer obtained by wire electrical discharge machining (WEDM) for 7075 aluminum alloy on the mechanical physical properties of the workpiece, we carried out research on the geometry parameters, microstructure, adhesion, wear resistance and corrosion resistance of the recast layer. The results show that the unit thermal power density decreases, the surface roughness Ra value increases, and the amount of the electric erosion craters and the micro/nano pits decrease with the increase of current and voltage. In the meantime, the thickness and hardness of the recast layer are increased, so the wear resistance and corrosion resistance are significantly improved. In addition, the surface hardness plays a major role in increasing wear resistance.

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

Sivasakthi, P.; Sekar, R.; Bapu, G.N.K.Ramesh, E-mail: bapu2657@yahoo.com

Highlights: • Nickel deposits from sulphamate solutions using pulse method are prepared. • Effect of duty cycle and frequency are studied. • XRD, SEM and AFM of the nickel deposits are characterized. • Corrosion characteristics of the nickel deposit are reported. - Abstract: Nickel deposits have been obtained on mild steel substrate by pulse current (PC) electrodeposition method using nickel sulphamate electrolyte. Micro hardness values increased with decreasing duty cycle and pulse frequency. X-ray diffraction studies revealed that (2 0 0) plane was predominant and the nickel deposit obtained at low duty cycle and low frequency has the smallest grainmore » size. The surface morphology of the coatings was explored by scanning electron microscopy (SEM) and atomic force microscopy. These studies showed that the microstructure of the nickel coatings changed from pyramidal structure to homogeneous structure with increasing duty cycle and pulse frequencies. The corrosion resistance of coatings was evaluated by potentiodynamic polarization and electrochemical impedance studies in 3.5 wt% sodium chloride (NaCl) solutions. An enhancement of the corrosion resistance, charge-transfer resistance and wear resistance has been obtained at low duty cycle and low frequencies.« less

Grain Boundary Resistivity of Yttria-Stabilized Zirconia at 1400°C

DOE PAGES

Wang, J.; Du, A.; Yang, Di; ...

2013-01-01

Tmore » he grain size dependence of the bulk resistivity of 3 mol% yttria-stabilized zirconia at 1400°C was determined from the effect of a dc electric field E a = 18.1  V/cm on grain growth and the corresponding electric current during isothermal annealing tests. Employing the brick layer model, the present annealing test results were in accordance with extrapolations of the values obtained at lower temperature employing impedance spectroscopy and 4-point-probe dc. he combined values give that the magnitude of the grain boundary resistivity ρ b = 133  ohm-cm. he electric field across the grain boundary width was 28–43 times the applied field for the grain size and current ranges in the present annealing test.« less

Compiling a national resistivity atlas of Denmark based on airborne and ground-based transient electromagnetic data

NASA Astrophysics Data System (ADS)

Barfod, Adrian A. S.; Møller, Ingelise; Christiansen, Anders V.

2016-11-01

We present a large-scale study of the petrophysical relationship of resistivities obtained from densely sampled ground-based and airborne transient electromagnetic surveys and lithological information from boreholes. The overriding aim of this study is to develop a framework for examining the resistivity-lithology relationship in a statistical manner and apply this framework to gain a better description of the large-scale resistivity structures of the subsurface. In Denmark very large and extensive datasets are available through the national geophysical and borehole databases, GERDA and JUPITER respectively. In a 10 by 10 km grid, these data are compiled into histograms of resistivity versus lithology. To do this, the geophysical data are interpolated to the position of the boreholes, which allows for a lithological categorization of the interpolated resistivity values, yielding different histograms for a set of desired lithological categories. By applying the proposed algorithm to all available boreholes and airborne and ground-based transient electromagnetic data we build nation-wide maps of the resistivity-lithology relationships in Denmark. The presented Resistivity Atlas reveals varying patterns in the large-scale resistivity-lithology relations, reflecting geological details such as available source material for tills. The resistivity maps also reveal a clear ambiguity in the resistivity values for different lithologies. The Resistivity Atlas is highly useful when geophysical data are to be used for geological or hydrological modeling.

REPLY: Reply to 'Comment on "Electron-phonon scattering in Sn-doped In2O3 FET nanowires probed by temperature-dependent measurements"'

NASA Astrophysics Data System (ADS)

Berengue, Olivia M.; Chiquito, Adenilson J.; Pozzi, Livia P.; Lanfredi, Alexandre J. C.; Leite, Edson R.

2009-11-01

In this reply we discuss the use of two and four-probe methods in the resistivity measurements of ITO nanowires. We pointed out that the results obtained by using two or four probe methods are indistinguishable in our case. Additionally we present the correct values for resistivity and consequently for the density of electrons.

Dynamic imaging in electrical impedance tomography of the human chest with online transition matrix identification.

PubMed

Moura, Fernando Silva; Aya, Julio Cesar Ceballos; Fleury, Agenor Toledo; Amato, Marcelo Britto Passos; Lima, Raul Gonzalez

2010-02-01

One of the electrical impedance tomography objectives is to estimate the electrical resistivity distribution in a domain based only on electrical potential measurements at its boundary generated by an imposed electrical current distribution into the boundary. One of the methods used in dynamic estimation is the Kalman filter. In biomedical applications, the random walk model is frequently used as evolution model and, under this conditions, poor tracking ability of the extended Kalman filter (EKF) is achieved. An analytically developed evolution model is not feasible at this moment. The paper investigates the identification of the evolution model in parallel to the EKF and updating the evolution model with certain periodicity. The evolution model transition matrix is identified using the history of the estimated resistivity distribution obtained by a sensitivity matrix based algorithm and a Newton-Raphson algorithm. To numerically identify the linear evolution model, the Ibrahim time-domain method is used. The investigation is performed by numerical simulations of a domain with time-varying resistivity and by experimental data collected from the boundary of a human chest during normal breathing. The obtained dynamic resistivity values lie within the expected values for the tissues of a human chest. The EKF results suggest that the tracking ability is significantly improved with this approach.

In situ measurement system

DOEpatents

Lord, D.E.

1980-11-24

A multipurpose in situ underground measurement system comprising a plurality of long electrical resistance elements in the form of rigid reinforcing bars, each having an open loop hairpin configuration of shorter length than the other resistance elements. The resistance elements are arranged in pairs in a unitized structure, and grouted in place in the underground volume. Measurement means are provided for obtaining for each pair the electrical resistance of each element and the difference in electrical resistance of the paired elements, which difference values may be used in analytical methods involving resistance as a function of temperature. A scanner means sequentially connects the resistance-measuring apparatus to each individual pair of elements. A source of heating current is also selectively connectable for heating the elements to an initial predetermined temperature prior to electrical resistance measurements when used as an anemometer.

Magnetic resonance electrical impedance tomography (MREIT): simulation study of J-substitution algorithm.

PubMed

Kwon, Ohin; Woo, Eung Je; Yoon, Jeong-Rock; Seo, Jin Keun

2002-02-01

We developed a new image reconstruction algorithm for magnetic resonance electrical impedance tomography (MREIT). MREIT is a new EIT imaging technique integrated into magnetic resonance imaging (MRI) system. Based on the assumption that internal current density distribution is obtained using magnetic resonance imaging (MRI) technique, the new image reconstruction algorithm called J-substitution algorithm produces cross-sectional static images of resistivity (or conductivity) distributions. Computer simulations show that the spatial resolution of resistivity image is comparable to that of MRI. MREIT provides accurate high-resolution cross-sectional resistivity images making resistivity values of various human tissues available for many biomedical applications.

Temporal Relationship Between Hyperuricemia and Insulin Resistance and Its Impact on Future Risk of Hypertension.

PubMed

Han, Tianshu; Lan, Li; Qu, Rongge; Xu, Qian; Jiang, Ruyue; Na, Lixin; Sun, Changhao

2017-10-01

Although hyperuricemia and insulin resistance significantly correlated, their temporal sequence and how the sequence influence on future risk of hypertension are largely unknown. This study assessed temporal relationship between uric acid and insulin resistance and its impact on future risk of hypertension by examining a longitudinal cohort including 8543 subjects aged 20 to 74 years from China, with an average follow-up of 5.3 years. Measurements of fasting uric acid, as well as fasting and 2-hour serum glucose and insulin, were obtained at baseline and follow-up. Indicators of hepatic and peripheral insulin resistance were calculated. Cross-lagged panel and mediation analysis were used to examine the temporal relationship between uric acid and insulin resistance and its impact on follow-up hypertension. After adjusting for covariates, the cross-lagged path coefficients ( β 1 values) from baseline uric acid to follow-up insulin resistance indices were significantly greater than path coefficients ( β 2 values) from baseline insulin resistance indices to follow-up uric acid ( β 1 =0.110 versus β 2 =0.017; P <0.001, for hepatic insulin resistance; β 1 =-0.208 versus β 2 =-0.021; P <0.001, for peripheral insulin resistance). The path coefficients from baseline uric acid to follow-up insulin resistance indices in the hypertensive group were significantly greater than that in the normotensive group ( P <0.001 for the difference of β 1 values in the 2 groups). Insulin resistance partially mediated the effect of uric acid on subsequent hypertension, and the mediation effect of peripheral insulin resistance was significantly greater than that of hepatic insulin resistance (31.3% versus 13.2%; P <0.001, for the difference of mediation effects). These findings provide evidence that higher uric acid levels probably precede insulin resistance, and peripheral insulin resistance likely plays a more important role in the development of hypertension than hepatic insulin resistance does. © 2017 American Heart Association, Inc.

In vitro corrosion behaviour of Ti-Nb-Sn shape memory alloys in Ringer's physiological solution.

PubMed

Rosalbino, F; Macciò, D; Scavino, G; Saccone, A

2012-04-01

The nearly equiatomic Ni-Ti alloy (Nitinol) has been widely employed in the medical and dental fields owing to its shape memory or superelastic properties. The main concern about the use of this alloy derives form the fact that it contains a large amount of nickel (55% by mass), which is suspected responsible for allergic, toxic and carcinogenic reactions. In this work, the in vitro corrosion behavior of two Ti-Nb-Sn shape memory alloys, Ti-16Nb-5Sn and Ti-18Nb-4Sn (mass%) has been investigated and compared with that of Nitinol. The in vitro corrosion resistance was assessed in naturally aerated Ringer's physiological solution at 37°C by corrosion potential and electrochemical impedance spectroscopy (EIS) measurements as a function of exposure time, and potentiodynamic polarization curves. Corrosion potential values indicated that both Ni-Ti and Ti-Nb-Sn alloys undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the aggressive environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Ti-18Nb-5Sn alloy. Significantly low anodic current density values were obtained from the polarization curves, indicating a typical passive behaviour for all investigated alloys, but Nitinol exhibited breakdown of passivity at potentials above approximately 450 mV(SCE), suggesting lower corrosion protection characteristics of its oxide film compared to the Ti-Nb-Sn alloys. EIS studies showed high impedance values for all samples, increasing with exposure time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The obtained EIS spectra were analyzed using an equivalent electrical circuit representing a duplex structure oxide film, composed by an outer and porous layer (low resistance), and an inner barrier layer (high resistance) mainly responsible for the alloys corrosion resistance. The resistance of passive film present on the metals' surface increases with exposure time displaying the highest values to Ti-18Nb-4Sn alloy. All these electrochemical results suggest that Ti-Nb-Sn alloys are promising materials for biomedical applications.

Computational model, method, and system for kinetically-tailoring multi-drug chemotherapy for individuals

DOEpatents

Gardner, Shea Nicole

2007-10-23

A method and system for tailoring treatment regimens to individual patients with diseased cells exhibiting evolution of resistance to such treatments. A mathematical model is provided which models rates of population change of proliferating and quiescent diseased cells using cell kinetics and evolution of resistance of the diseased cells, and pharmacokinetic and pharmacodynamic models. Cell kinetic parameters are obtained from an individual patient and applied to the mathematical model to solve for a plurality of treatment regimens, each having a quantitative efficacy value associated therewith. A treatment regimen may then be selected from the plurlaity of treatment options based on the efficacy value.

Aeromonas Diversity and Antimicrobial Susceptibility in Freshwater-An Attempt to Set Generic Epidemiological Cut-Off Values.

PubMed

Baron, Sandrine; Granier, Sophie A; Larvor, Emeline; Jouy, Eric; Cineux, Maelan; Wilhelm, Amandine; Gassilloud, Benoit; Le Bouquin, Sophie; Kempf, Isabelle; Chauvin, Claire

2017-01-01

The importance of the role of environment in the dissemination of antimicrobial resistant bacteria is now well recognized. Thus, bacterial indicators to monitor the phenomena are required. The Aeromonas genus is autochthonous in the aquatic environment and easy to detect in any water type, such as freshwater, or wastewater. These microorganisms are also causing infections in humans and animals (including fish). Furthermore, as Aeromonas spp. is able to acquire antimicrobial resistance mechanisms, it is candidate for indicator bacteria to follow antimicrobial resistance dissemination in aquatic environments. Unfortunately, to date, interpretation criteria for Aeromonas spp. for antimicrobial susceptibility tests are scarce in the literature. No epidemiological cut-off values for Aeromonas are currently available at EUCAST to interpret Minimum Inhibitory Concentrations (MIC). The only interpretation criteria available are clinical breakpoints from CLSI that are adapted from Enterobacteriaceae . Based on the results of MIC distributions obtained for a collection of environmental isolates of Aeromonas , this study aimed at proposing tentative epidemiological cut-off values (CO WT ) for Aeromonas spp. assessing whether the genus is an acceptable level of definition. Thus, 233 isolates collected from 16 rivers were identified at species level using Maldi-Tof (Bruker). Eleven different species were identified, the most abundant were A. bestiarum ( n = 54), A. salmonicida ( n = 45), A. sobria ( n = 41), and A. eucrenophila ( n = 37). 96-well micro-plates containing different concentrations of 15 antimicrobials, namely cefotaxime, ceftazidime, chloramphenicol, colistin, enrofloxacin, erythromycin, florfenicol, flumequine, gentamicin, nalidixic acid, oxolinic acid, streptomycin, temocillin, tetracycline, and trimethoprim-sulfamethoxazole, were prepared. The broth micro-dilution method was used to determine the antimicrobial susceptibility of each isolate. The estimation of CO WT values was satisfactory obtained at genus level for all antimicrobials except cefotaxime and erythromycin. This first step is an invitation for other research teams to increase the amount of antimicrobial resistance data collected. Then, robustness of our proposed provisional generic epidemiological cut-off values could be assessed by testing antimicrobial susceptibility of various Aeromonas collections.

Impact of the geological structures on the groundwater potential using geophysical techniques in West Bani Mazar area, El Minia - Western Desert, Egypt

NASA Astrophysics Data System (ADS)

Mahmoud, Hussein Hosni; Kotb, Adel Diab Mohammed

2017-06-01

Establishment of the new agricultural projects in west Bani Mazar area, El Minia, Egypt needs a good knowledge about groundwater. Groundwater serves as the unique source of water supplies in the study area. Vertical Electrical Sounding technique is a convenient tool for groundwater exploration. This technique was utilized to illustrate the geoelectric succession, vertical and spatial extensions of the encountered layers, depth to water bearing layers and the structures affecting these layers. Profiling technique was carried out along a grid pattern using different half current electrode spacings (150 m, 300 m and 500 m) to clarify changes in resistivity values throughout the study area at different depths. Geoelectric layers B1 and B2 of the saturated zone are suitable for groundwater extraction in the study area. The resistivity values of the geoelectric layer B1 decrease towards the West direction, they decrease from 23.0 Ωm to 16.0 Ωm; and its thicknesses increase towards the SE direction from 12.0 m to 18.0 m. Whereas, the resistivity values of the geoelectric layer B2 decrease towards the NW direction from 40.0 Ωm to 26.5 Ωm; and its thicknesses vary from 34.0 m to 40.0 m. The depths to the upper surface of the water bearing layer B1 increase towards the NW direction from 44.0 m to 89.4 m. Based on the results obtained from the Vertical Electrical Soundings, four two-dimensional resistivity imaging profiles were measured at the selected sites. These 2-D resistivity profiles aim to determine depths to the water bearing layers, their thicknesses and the shallow structure. The inverted models of these profiles matched with the geoelectric sequence at these sites. In addition, a normal fault is detected at the northwestern part of the study area. According to the results obtained from this study it is clear that the groundwater in the area under consideration is occurred in the fractured limestone layers that belong to Eocene Age. Resistivity values of the water bearing layers increase with depth as a result of decreasing fracture density; and these values decreased towards the northwestern direction due to their proximity from the fault zone. The groundwater potential of these layers depends mainly on the lithologic composition and the geological structures affecting these layers. The secondary porosity of these limestone layers depends mainly on the degree of fracturing and fissuring. The proper sites to drill new productive wells were recommended, and the obtained data from drilling new well in the southeastern part of the study area coincide with the interpreted data of the different geophysical techniques.

Effect of aggregate graining compositions on skid resistance of Exposed Aggregate Concrete pavement

NASA Astrophysics Data System (ADS)

Wasilewska, Marta; Gardziejczyk, Wladysław; Gierasimiuk, Pawel

2018-05-01

The paper presents the evaluation of skid resistance of EAC (Exposed Aggregate Concrete) pavements which differ in aggregate graining compositions. The tests were carried out on concrete mixes with a maximum aggregate size of 8 mm. Three types of coarse aggregates were selected depending on their resistance to polishing which was determined on the basis of the PSV (Polished Stone Value). Basalt (PSV 48), gabbro (PSV 50) and trachybasalt (PSV 52) aggregates were chosen. For each type of aggregate three graining compositions were designed, which differed in the content of coarse aggregate > 4mm. Their content for each series was as follows: A - 38%, B - 50% and C - 68%. Evaluation of the skid resistance has been performed using the FAP (Friction After Polishing) test equipment also known as the Wehner/Schulze machine. Laboratory method enables to compare the skid resistance of different types of wearing course under specified conditions simulating polishing processes. In addition, macrotexture measurements were made on the surface of each specimen using the Elatexure laser profile. Analysis of variance showed that at significance level α = 0.05, aggregate graining compositions as well as the PSV have a significant influence on the obtained values of the friction coefficient μm of the tested EAC pavements. The highest values of the μm have been obtained for EAC with the lowest amount of coarse aggregates (compositions A). In these cases the resistance to polishing of the aggregate does not significantly affect the friction coefficients. This is related to the large areas of cement mortar between the exposed coarse grains. Based on the analysis of microscope images, it was observed that the coarse aggregates were not sufficiently exposed. It has been proved that PSV significantly affected the coefficient of friction in the case of compositions B and C. This is caused by large areas of exposed coarse aggregate. The best parameters were achieved for the EAC pavements with graining composition B and C and trachybasalt aggregate.

Magnetoresistance in single-electron transistors comprising a superconducting island with ferromagnetic leads

NASA Astrophysics Data System (ADS)

Mizugaki, Yoshinao; Takiguchi, Masashi; Tamura, Nobuyuki; Shimada, Hiroshi

2018-03-01

We report electric and magnetic field responses of single-electron transistors (SETs) comprising a superconducting island with ferromagnetic (FM) leads. We fabricated two SETs, one of which had relatively high resistance and the other had relatively low resistance. The SETs had two states for the gate charge: SET-ON or SET-OFF. They also had two states for the FM lead magnetization: parallel (P) or anti-parallel (AP) configuration. Current-voltage characteristics of four SET states (“P & SET-ON,” “P & SET-OFF,” “AP & SET-ON,” and “AP & SET-OFF”) were measured at approximately 0.1 K in a compact dilution refrigerator. Magnetoresistance ratio (MRR) values were obtained for the SET-ON and SET-OFF states, respectively. The higher-resistance SET1 exhibited positive MRR values for all measured bias voltages. The MRR enhancement was confirmed for the SET-OFF state, which agreed well with the co-tunneling model. The lower-resistance SET2, on the other hand, exhibited negative and positive MRR values for higher and lower bias voltage conditions, respectively. The bias voltage for the MRR polarity reversal was changed by the gate voltage. It was also confirmed that the co-tunneling model was partially valid for negative MRR values.

Reference values of MostGraph measures for middle-aged and elderly Japanese individuals who participated in annual health checkups.

PubMed

Abe, Yuki; Shibata, Yoko; Igarashi, Akira; Inoue, Sumito; Sato, Kento; Sato, Masamichi; Nemoto, Takako; Kobayashi, Maki; Nishiwaki, Michiko; Kimura, Tomomi; Tokairin, Yoshikane; Kayama, Takamasa; Kubota, Isao

2016-05-01

The forced oscillation technique (FOT) can measure respiratory system resistance and reactance under tidal volume respiration. MostGraph is a device that incorporates the FOT and enables the immediate, three-dimensional visualization of resistance and reactance parameters. The aim of this study was to establish MostGraph reference values for middle-aged and elderly Japanese individuals. From 2004 to 2006, 3253 subjects living in Takahata, Yamagata underwent spirometry. Of these, 872 again underwent spirometry in 2011, and 784 (368 men, ages 46-89 years; 416 women, ages 47-90 years) underwent FOT examinations using MostGraph-01. In this study population, 19.0% of the men and 91.5% of the women were life-long never smokers. Abnormal spirometric findings were observed in 30.2% of the men and 14.6% of the women. Although the respiratory system resistance and reactance parameters obtained using MostGraph were not distributed normally, normal distribution was achieved via natural logarithm (R5, R20, Fres, and ALX), square root (R5-R20), or exponential (X5) transformation. Furthermore, the transformed values were converted back to the actual values after determining the values representing one and two standard deviations from the mean. Respiratory system resistance and reactance reference values were determined using MostGraph in middle-aged and elderly Japanese individuals who participated in annual health checkups. Copyright © 2016 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Determination of slope failure using 2-D resistivity method

NASA Astrophysics Data System (ADS)

Muztaza, Nordiana Mohd; Saad, Rosli; Ismail, Nur Azwin; Bery, Andy Anderson

2017-07-01

Landslides and slope failure may give negative economic effects including the cost to repair structures, loss of property value and medical costs in the event of injury. To avoid landslide, slope failure and disturbance of the ecosystem, good and detailed planning must be done when developing hilly area. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. The study on landslide and slope failure was conducted at Site A and Site B, Selangor using 2-D resistivity method. The implications of the anticipated ground conditions as well as the field observation of the actual conditions are discussed. Nine 2-D resistivity survey lines were conducted in Site A and six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed in Site B. The data were processed using Res2Dinv and Surfer10 software to evaluate the subsurface characteristics. 2-D resistivity results from both locations show that the study areas consist of two main zones. The first zone is alluvium or highly weathered with the resistivity of 100-1000 Ωm at 20-70 m depth. This zone consists of saturated area (1-100 Ωm) and boulders with resistivity value of 1200-3000 Ωm. The second zone with resistivity values of > 3000 Ωm was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. Based on the results obtained from the study findings, it can be concluded that 2-D resistivity method is useful method in determination of slope failure.

Thermal resistance of Saccharomyces yeast ascospores in beers.

PubMed

Milani, Elham A; Gardner, Richard C; Silva, Filipa V M

2015-08-03

The industrial production of beer ends with a process of thermal pasteurization. Saccharomyces cerevisiae and Saccharomyces pastorianus are yeasts used to produce top and bottom fermenting beers, respectively. In this research, first the sporulation rate of 12 Saccharomyces strains was studied. Then, the thermal resistance of ascospores of three S. cerevisiae strains (DSMZ 1848, DSMZ 70487, Ethanol Red(®)) and one strain of S. pastorianus (ATCC 9080) was determined in 4% (v/v) ethanol lager beer. D60 °C-values of 11.2, 7.5, 4.6, and 6.0 min and z-values of 11.7, 14.3, 12.4, and 12.7 °C were determined for DSMZ 1848, DSMZ 70487, ATCC 9080, and Ethanol Red(®), respectively. Lastly, experiments with 0 and 7% (v/v) beers were carried out to investigate the effect of ethanol content on the thermal resistance of S. cerevisiae (DSMZ 1848). D55 °C-values of 34.2 and 15.3 min were obtained for 0 and 7% beers, respectively, indicating lower thermal resistance in the more alcoholic beer. These results demonstrate similar spore thermal resistance for different Saccharomyces strains and will assist in the design of appropriate thermal pasteurization conditions for preserving beers with different alcohol contents. Copyright © 2015 Elsevier B.V. All rights reserved.

Study of Sedimentary Outcrop of Semanggol Formation with the Correlation of Geology, Geotechnical and Geophysics Technique

NASA Astrophysics Data System (ADS)

Nordiana, A. N.; Nordiana, M. M.; Jia, Teoh Ying; Hisham, Hazrul; Sulaiman, Nabila; Maslinda, Umi; Taqiuddin, Z. M.; Nur Amalina, M. K. A.; Afiq Saharudin, Muhamad

2017-04-01

The study location was at Bukit Kukus, Kuala Ketil, Kedah, Malaysia where the geological outcrop of this Semanggol Formation comprises of chert, mudstone, and volcanic tuff. The study was conducted using two geophysical methods, which are 2-D Resistivity and Ground Penetrating Radar (GPR). The objectives of the study are to correlate both of the geophysical methods through the value of conductivity and to identify the physical properties of rocks through the value of porosity and permeability. The data acquisition for both methods was conducted on the same line. For 2-D Resistivity method, the length of the line is 60 m with 1.5 m electrode spacing and the array used was Wenner-Schlumberger. For GPR method, the survey line was on top of the resistivity line, and the frequency of the antenna used is 250 MHz. A good correlation exists between both of the GPR signature and contour maps for resistivity from the surfer 10 software with the outcrop feature. Conductivity value from both GPR and Resistivity method was compared and the range value of conductivity obtained from GPR method almost equivalent with Resistivity method based on derivation and calculation for the sedimentary rocks, which are 0.037 to 0.574 miliSiemens per metre (mS/m) for chert and 0.186 to 10.142 miliSiemens per metre (mS/m) for mudstone. Two types of rock samples were taken, and several geotechnical tests were conducted, but only the value of permeability, K and porosity, ɸ of chert can be calculated, which are 1.95E-22 m2 (original condition) and 2.27E-22 m2 (dry condition) and 3 percent respectively as the sample of mudstone was damaged. The parameter of the 2-D resistivity method derived from Archie’s law was used to calculate the porosity, ɸf value using the Formation Factor equation. The range values of porosity, ɸf for chert mostly in the range of 5 to 25 percent, which is 6.26 to 13.36 percent but slightly out of range for mudstone, which is 14.12 to 36.02 percent.

Self-Test Procedures for Gas Sensors Embedded in Microreactor Systems

PubMed Central

Helwig, Andreas; Hackner, Angelika; Zappa, Dario; Sberveglieri, Giorgio

2018-01-01

Metal oxide (MOX) gas sensors sensitively respond to a wide variety of combustible, explosive and poisonous gases. However, due to the lack of a built-in self-test capability, MOX gas sensors have not yet been able to penetrate safety-critical applications. In the present work we report on gas sensing experiments performed on MOX gas sensors embedded in ceramic micro-reaction chambers. With the help of an external micro-pump, such systems can be operated in a periodic manner alternating between flow and no-flow conditions, thus allowing repetitive measurements of the sensor resistances under clean air, R0, and under gas exposure, Rgas, to be obtained, even under field conditions. With these pairs of resistance values, eventual drifts in the sensor baseline resistance can be detected and drift-corrected values of the relative resistance response Resp=(R0−Rgas)/R0 can be determined. Residual poisoning-induced changes in the relative resistance response can be detected by reference to humidity measurements taken with room-temperature-operated capacitive humidity sensors which are insensitive to the poisoning processes operative on heated MOX gas sensors. PMID:29401673

Analysis of Manning’s and Drag Coefficients for Flexible Submerged Vegetation

NASA Astrophysics Data System (ADS)

Yusof, Khamaruzaman Wan; Mujahid Muhammad, Muhammad; Mustafa, Muhammad Raza Ul; Azazi Zakaria, Nor; Gahani, Aminuddin Ab.

2017-06-01

Accurate determination of flow resistance is of great significance in modelling of open channels that will convey water efficiently. Although, resistance or drag induced by vegetation have been systematically studied for several decades, estimating of the resistance remain as a challenge. This is because most of previous studies use artificial vegetation to investigate flow - vegetation interactions. To overcome this, the present study evaluates the vegetation resistance in terms of Manning’s roughness coefficient and drag coefficient using a natural flexible vegetation (cow grass) under submerged condition. From the experimental result obtained, it was observed that the Manning’s and drag coefficients decreased with the increasing in average velocity. Also, graphical relationship between Manning’s coefficient, n and drag coefficient, CD has been developed with R2 = 0.9465, which indicate that there exist a strong correlation between n and CD, and one can use the proposed graphical model to predict the n - values corresponding to the CD - values.

The correlation of 2D-resistivity and magnetic methods in fault verification at northern Sumatra, Indonesia

NASA Astrophysics Data System (ADS)

Kamaruddin, Nur Aminuda; Saad, Rosli; Nordiana, M. M.; Azwin, I. N.

2015-04-01

The Great Sumatra Fault system was split into two sub-parallel lines or segments at the Northern Sumatra. This event is one of the impacts of powerful earthquakes that hit Sumatra Island especially one that occurred in 2004. These two sub-parallel segments known as Aceh and Seulimeum fault. The study is focused on the Seulimeum fault and two geophysical methods chosen aimed to compare and verified the result obtained respectively. 2-D resistivity method is a common geophysical method used in determination of near surface structures such as faults, cavities, voids and sinkholes. Meanwhile, the magnetic method often chosen to delineate subsurface structures, determine depth of magnetic source bodies and possibly sediment thickness. Three survey lines of resistivity method and randomly magnetic stations were carried out covering Krueng district. The resistivity data processed using Res2Dinv and result presented using Surfer software. The fault identified by the contrast of low and high resistivity value. Meanwhile, the magnetic data were presented in magnetic residual contour map and the extended fault system is suspected represent by the contrast value of the magnetic anomalies. Within suspected fault zone, the results of resistivity are tally with magnetic result.

Reversal of in vitro cellular MRP1 and MRP2 mediated vincristine resistance by the flavonoid myricetin.

PubMed

van Zanden, Jelmer J; de Mul, Anika; Wortelboer, Heleen M; Usta, Mustafa; van Bladeren, Peter J; Rietjens, Ivonne M C M; Cnubben, Nicole H P

2005-06-01

In the present study, the effects of myricetin on either MRP1 or MRP2 mediated vincristine resistance in transfected MDCKII cells were examined. The results obtained show that myricetin can inhibit both MRP1 and MRP2 mediated vincristine efflux in a concentration dependent manner. The IC50 values for cellular vincristine transport inhibition by myricetin were 30.5+/-1.7 microM for MRP1 and 24.6+/-1.3 microM for MRP2 containing MDCKII cells. Cell proliferation analysis showed that the MDCKII control cells are very sensitive towards vincristine toxicity with an IC50 value of 1.1+/-0.1 microM. The MDCKII MRP1 and MRP2 cells are less sensitive towards vincristine toxicity with IC50 values of 33.1+/-1.9 and 22.2+/-1.4 microM, respectively. In both the MRP1 and MRP2 cells, exposure to 25 microM myricetin enhances the sensitivity of the cells towards vincristine toxicity to IC50 values of 7.6+/-0.5 and 5.8+/-0.5 microM, respectively. The increase of sensitivity represents a reversal of the resistance towards vincristine as a result of MRP1 and MRP2 inhibition. Thus, the present study demonstrates the ability of the flavonoid myricetin to modulate MRP1 and MRP2 mediated resistance to the anticancer drug vincristine in transfected cells, indicating that flavonoids might be a valuable adjunct to chemotherapy to block MRP mediated resistance.

[Assessment of resistant hypertension with home blood pressure monitoring].

PubMed

Marui, Fabiane Rosa Rezende H; Bombig, Maria Teresa Nogueira; Francisco, Yoná Afonso; Thalenberg, José Marcos; Fonseca, Francisco Antonio Helfenstein; Souza, Dilma de; Costa, Francisco de Assis; Izar, Maria Cristina; Carvalho, Antonio Carlos de Camargo; Póvoa, Rui

2010-10-01

ambulatory blood pressure monitoring (ABPM) is considered the gold standard for the diagnostic confirmation of resistant hypertension (RH). However, home blood pressure monitoring (HBPM) has been considered an option, because of its lower cost and greater comfort. to compare the values obtained by HBPM with those obtained by ABPM in the identification of patients with resistant hypertension. a total of 51 consecutive patients with resistant hypertension were selected. All were adults of both genders and were undergoing treatment in an outpatient referral clinic from January 2007 to September 2009. Casual office blood pressure (BP), 24-hour ABPM, and HBPM were performed according to current guidelines, with a maximum two-week interval between the methods. the comparison of ABPM (mean daytime) with HBPM showed a good correlation between them, both for systolic blood pressure (SBP) and for diastolic blood pressure (DBP): SBP r = 0.70, CI = 0.51-0.82, DBP r = 0.69, CI = 0.52-0.81. RH was confirmed by ABPM in 33 patients and by HBPM in 37, with no significant difference between the methods. according to the results obtained, we conclude that HBPM is a method that can be used as an alternative to ABPM for the diagnostic confirmation of RH.

Department of Defense Annual Report on Sexual Assault in the Military, Fiscal Year 2014

DTIC Science & Technology

2015-04-22

focused on the following objectives: • Determine whether club culture promotes or resists adherence to Army and USMA values, and why. • Obtain... firing range. The Subject would tell certain female trainees to spread their legs, and he would use the metal detector to touch the females in their...after she "gave up" attempting to resist after repeatedly telling him to stop during the previous progression of sexual contacts. Sexual Assault

Floor tile glass-ceramic glaze for improvement of the resistance to surface abrasion

NASA Astrophysics Data System (ADS)

Gajek, M.; Lis, J.; Partyka, J.; Wójczyk, M.

2011-10-01

The results of research aimed at the study on frits and glass-ceramic glazes for floor tiles, based on compositions located in the primary field of cordierite crystallization within the system MgO-Al2O3-SiO2, have been presented. The results comprise investigations on the frits crystallization abilities, stability of the crystallizing phase under conditions of single-stage a fast firing cycle (time below 60 minutes) depending on their chemical composition and the influence of the nucleation agents. The influence of the nucleating agents namely TiO2, ZrO2, V2O5 on phase composition of obtained crystalline glazes, mechanical parameters and microstructure, has been examined. The strength tests proved increased mechanical resistance of crystalline glazes. Obtained glazes are characterized by high microhardness in range 6~8 GPa, as well as the increased wear resistance measured by the loss of weight below 100 mg / 55 cm2 (PN-EN ISO 10545-7). Significant increase of these parameters as compared with non-crystalline glazes, where micro-hardness values range between 5~6 GPa and the wear resistance values range from 120 to 200 mg, has been proved. Starting glasses (frits) and glazes of the ternary system MgO-SiO2-Al2O3, were examined with use of DTA, XRD and SEM methods.

Atomic layer deposition synthesized TiO{sub x} thin films and their application as microbolometer active materials

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

Tanrikulu, Mahmud Yusuf, E-mail: mytanrikulu@adanabtu.edu.tr; Rasouli, Hamid Reza; Ghaffari, Mohammad

2016-05-15

This paper demonstrates the possible usage of TiO{sub x} thin films synthesized by atomic layer deposition as a microbolometer active material. Thin film electrical resistance is investigated as a function of thermal annealing. It is found that the temperature coefficient of resistance values can be controlled by coating/annealing processes, and the value as high as −9%/K near room temperature is obtained. The noise properties of TiO{sub x} films are characterized. It is shown that TiO{sub x} films grown by atomic layer deposition technique could have a significant potential to be used as a new active material for microbolometer-based applications.

Bipolar resistive switching in Si/Ag nanostructures

NASA Astrophysics Data System (ADS)

Dias, C.; Lv, H.; Picos, R.; Aguiar, P.; Cardoso, S.; Freitas, P. P.; Ventura, J.

2017-12-01

Resistive switching devices are being intensively studied aiming a large number of promising applications such as nonvolatile memories, artificial neural networks and sensors. Here, we show nanoscale bipolar resistive switching in Pt/Si/Ag/TiW structures, with a dielectric barrier thickness of 20 nm. The observed phenomenon is based on the formation/rupture of metallic Ag filaments in the otherwise insulating Si host material. No electroforming process was required to achieve resistive switching. We obtained average values of 0.23 V and -0.24 V for the Set and Reset voltages, respectively. The stability of the switching was observed for over 100 cycles, together with a clear separation of the ON (103 Ω) and OFF (102 Ω) states. Furthermore, the influence of the Set current compliance on the ON resistance, resistances ratio and Set/Reset voltages percentage variation was also studied.

Antibacterial resistance in Streptococcus pyogenes (GAS) from healthy carriers and tonsillitis patients and association with antibacterial sale in the Faroe Islands.

PubMed

Magnussen, Marita D; Gaini, Shahin; Gislason, Hannes; Kristinsson, Karl G

2016-04-01

The aim of this study was to investigate the antibacterial resistance of Streptococcus pyogenes (GAS), and correlate the findings with the sales of erythromycin and tetracycline. General practitioners in the Faroe Islands were recruited to send oropharyngeal swabs. From an ongoing pneumococcal study, nasopharyngeal swabs were sampled from healthy children 0-7 years of age. Erythromycin susceptibility data from Iceland were obtained from the reference laboratory at the Landspitali University Hospital. Susceptibility testing in the Faroe Islands and Iceland was performed according to CLSI methods and criteria. The resistance rate to erythromycin and tetracycline found in patients in the Faroe Islands in 2009/2010 was 6% and 30% respectively. Tetracycline resistance in patients declined significantly from 2009 to 2010 (37-10%, p-value = 0.006 < 0.05) and differed significantly between age groups (p-value = 0.03 < 0.05). In Iceland, there was a peak in erythromycin resistance in 2008 (44%) and a substantial decrease in 2009 (5%). Although the prevalence of erythromycin and tetracycline resistance in the Faroe Islands and Iceland may be associated with antimicrobial use, sudden changes can occur with the introduction of new resistant clones. © 2016 APMIS. Published by John Wiley & Sons Ltd.

Origins of 1/f noise in nanostructure inclusion polymorphous silicon films

PubMed Central

2011-01-01

In this article, we report that the origins of 1/f noise in pm-Si:H film resistors are inhomogeneity and defective structure. The results obtained are consistent with Hooge's formula, where the noise parameter, αH, is independent of doping ratio. The 1/f noise power spectral density and noise parameter αH are proportional to the squared value of temperature coefficient of resistance (TCR). The resistivity and TCR of pm-Si:H film resistor were obtained through linear current-voltage measurement. The 1/f noise, measured by a custom-built noise spectroscopy system, shows that the power spectral density is a function of both doping ratio and temperature. PMID:21711802

[Study on Trace Water Influence on Electrical Properties of Insulating Oil Based on the Mid-Infrared Spectrum Analysis].

PubMed

Chen, Bin; Wu, Hong-yang; Han, Chao; Yan, Huan; Liu, Ge

2015-10-01

Trace water has a significant impact on the electrical performances of the insulating oil, such as the dielectric loss factor, resistivity. So there is an important significance to investigate the influence of insulating oil by trace water, and monitor its operating status with effective measures. First, it is necessary to prepare the insulating oil samples with different water content and treat them 8 hours with ultrasonic oscillator, and observe microscopic images about the water-oil mixtures in order to study their relative uniformity and stable time, in the way it can be concluded that the relative uniformity can be kept favorable during the 25 min stable time for free water and emulsification water in oil; Based on this conclusion, the dielectric loss factor, resistivity were tested and the electrical performances of insulating oil with different water content in oil can obtained by analyzing these data; Then, the absorbance value of the different water content in oil at the spectral wave number of 1 640, 3 400, 3 450, 3 615 cm(-1), with the mid-infrared spectral scanning and analyzing to the different water content in oil, Therefore, combined the water absorbance values by the mid-infrared spectral scanning and analyzing with the experimental data of dielectric loss factor value, resistivity value of oil samples. The results shows that the absorbance value of the different water content in oil has a significant difference at the spectral wave number of 1 640, 3 400, 3450, 3 615 cm(-1), their correlation coefficient are 0.964 1, 0.984 8, 0.984 5, 0.944 0 between the absorbance value and water content at the spectral wave number of 1 640, 3 400, 3 450, 3 615 cm(-1), it can be obtained that the absorbance value of sample of moisture in the corresponding characteristic wave number can better reflect the change trend of water content; there is the highly relative of water absorbance values at the spectral wave number of 3 400 and 3 450 cm(-1) with the trends of oil dielectric loss factor values, their correlation coefficient are 0.860 6, 0.863 6; and relative of water absorbance values at the spectral wave number of 1 640 and 3 615 cm(-1) with the trends of oil resistivity values, their correlation coefficient is -0.931 5 and -0.968 0, this result can be lay the foundation research for monitoring the trace water in oil.

Improvement of insulin resistance and reduction of cardiovascular risk among obese patients with type 2 diabetes with the duodenojejunal bypass liner.

PubMed

de Moura, Eduardo Guimarães Hourneaux; Orso, Ivan Roberto Bonotto; Martins, Bruno da Costa; Lopes, Guilherme Sauniti; de Oliveira, Suzana Lopes; Galvão-Neto, Manoel dos Passos; Mancini, Marcio Correa; Santo, Marco Aurélio; Sakai, Paulo; Ramos, Almino Cardoso; Garrido-Júnior, Arthur Belarmino; Halpern, Alfredo; Cecconello, Ivan

2011-07-01

This study aims to evaluate the effectiveness of the duodenojejunal bypass liner (DJBL) in the improvement of insulin resistance and reduction of cardiovascular risk among morbidly obese patients with type 2 diabetes mellitus, using the triglyceride/high-density lipoprotein (HDL) cholesterol ratio, percentage of weight loss, and glycemic control. We used the TG/HDL ratio with a cutoff value of 3.5 to identify patients with insulin resistance. The value of the initial ratio was compared with the ratio obtained 6 months after implantation to evaluate whether an improvement in insulin resistance occurred. We also evaluated the improvement of glycated hemoglobin levels and the weight loss resulted from the use of the device and correlated that with the improvement of the TG/HDL ratio. All patients implanted with the device presented a statistically significant reduction of the HbA1c levels, with most patients (70.3%) obtaining diabetes control with HbA1c levels lower than 7% at the end of the study. All patients also presented a significant weight reduction, with an average loss of 12.6% of their initial weight. We observed an important improvement in insulin resistance and metabolic syndrome, with a significant reduction of the TG/HDL ratio from 5.75 to 4.36 (p < 0.001) and 42.6% of the patients presenting a TG/HDL ratio lower than 3.5 at the end of the study. The DJBL, when used for a period of 6 months, is effective in the control of diabetes, weight loss, improvement of insulin resistance, and decrease of cardiovascular risk among morbidly obese patients with type 2 diabetes mellitus.

Chronicle of Bukit Bunuh for possible complex impact crater by 2-D resistivity imaging (2-DERI) with geotechnical borehole records

NASA Astrophysics Data System (ADS)

Jinmin, M.; Saad, R.; Saidin, M.; Ismail, N. A.

2015-03-01

A 2-D resistivity imaging (2-DERI) study was conducted at Bukit Bunuh, Lenggong, Perak. Archaeological Global Research Centre, Universiti Sains Malaysia shows the field evidence of shock metamorphisms (suevite breccia) and crater morphology at Bukit Bunuh. A regional 2-DERI study focusing at Bukit Bunuh to identify the features of subsurface and detail study was then executed to verify boundary of the crater with the rebound effects at Bukit Bunuh which covered approximately 132.25 km2. 2-DERI survey used resistivity equipment by ABEM SAS4000 Terrameter and ES10-64C electrode slector with pole-dipole array. The survey lines were carried out using `roll-along' technique. The data were processed and analysed using RES2DINV, Excel and Surfer software to obtain resistivity results for qualitative interpretations. Bedrock depths were digitized from section by sections obtained. 2-DERI results gives both regional and detail study shows that the study area was divided into two main zones, overburden consists of alluvium mix with boulders embedded with resistivity value of 10-800 Ωm and granitic bedrock with resistivity value of >1500 Ωm and depth 5-50 m. The low level bedrock was circulated by high level bedrock (crater rim) was formed at the same area with few spots of high level bedrock which appeared at the centre of the rim which suspected as rebound zones (R). Assimilations of 2-DERI with boreholes are successful give valid and reliable results. The results of the study indicates geophysical method are capable to retrieve evidence of meteorite impact subsurface of the studied area.

Effects of stoichiometry, purity, etching and distilling on resistance of MgB 2 pellets and wire segments

NASA Astrophysics Data System (ADS)

Ribeiro, R. A.; Bud'ko, S. L.; Petrovic, C.; Canfield, P. C.

2002-11-01

We present a study of the effects of non-stoichiometry, boron purity, wire diameter and post-synthesis treatment (etching and Mg distilling) on the temperature dependent resistance and resistivity of sintered MgB 2 pellets and wire segments. Whereas the residual resistivity ratio (RRR) varies between RRR≈4 to RRR⩾20 for different boron purity, it is only moderately affected by non-stoichiometry (from 20% Mg deficiency to 20% Mg excess) and is apparently independent of wire diameter and presence of Mg metal traces on the wire surface. The obtained set of data indicates that RRR values in excess of 20 and residual resistivities as low as ρ 0≈0.4 μΩ cm are intrinsic material properties of high purity MgB 2.

The role of outer membrane in Serratia marcescens intrinsic resistance to antibiotics.

PubMed

Sánchez, L; Ruiz, N; Leranoz, S; Viñas, M; Puig, M

1997-09-01

Three different porins from Serratia marcescens were described. They were named Omp1, Omp2 and Omp3 and their molecular weights were 42, 40 and 39 kDa respectively. Omp2 and Omp3 showed osmoregulation and thermoregulation in a similar way to OmpC and OmpF of Escherichia coli. Permeability coefficients of the outer membrane of this species were calculated following the Zimmermann and Rosselet method. P values were similar to those obtained in Escherichia coli, which suggests that the chromosomal beta-lactamase would play a major role in the resistance of Serratia marcescens to beta-lactam antibiotics. Both MIC values and permeabilities were modified by salycilates and acetylsalycilate. Synergism between the outer membrane and the beta-lactamase was also evaluated. When bacteria grew in the presence of a beta-lactam in the medium, the beta-lactamase accounted for most of the resistance.

Characterization of Resistance Patterns and Detection of Apramycin Resistance Genes in Escherichia coli Isolated from Chicken Feces and Houseflies after Apramycin Administration.

PubMed

Zhang, Anyun; Li, Yunxia; Guan, Zhongbin; Tuo, Hongmei; Liu, Dan; Yang, Yanxian; Xu, Changwen; Lei, Changwei; Wang, Hongning

2018-01-01

The aim of this study was to evaluate the influence of apramycin administration on the development of antibiotic resistance in Escherichia coli ( E. coli ) strains isolated from chicken feces and houseflies under field conditions. Chickens in the medicated group ( n = 25,000) were given successive prophylactic doses (0.5 mg/l) of apramycin in their drinking water from Days 1 to 5, while no antibiotics were added to the un-medicated groups drinking water ( n = 25,000). Over 40 days, a total of 1170 E. coli strains were isolated from fecal samples obtained from medicated and un-medicated chickens and houseflies from the same chicken farm. Apramycin MIC90 values for E. coli strains obtained from the medicated group increased 32-128 times from Days 2 to 6 (256-1024 μg/ml) when compared to those on Day 0 (8 μg/ml). Strains isolated from un-medicated chickens and houseflies had consistently low MIC90 values (8-16 μg/ml) during the first week, but showed a dramatic increase from Days 8 to 10 (128-1024 μg/ml). The apramycin resistance gene aac(3)-IV was detected in E. coli strains from medicated ( n = 71), un-medicated ( n = 32), and housefly groups ( n = 42). All strains positive for aac(3)-IV were classified into 12 pulsed-field gel electrophoresis (PFGE) types. PFGE types A, E, and G were the predominant types in both the medicated and housefly groups, suggesting houseflies play an important role in spreading E. coli -resistant strains. Taken together, our study revealed that apramycin administration could facilitate the occurrence of apramycin-resistant E. coli and the apramycin resistance gene acc(3)-IV . In turn, these strains could be transmitted by houseflies, thus increasing the potential risk of spreading multi-drug-resistant E. coli to the public.

Characterization of Resistance Patterns and Detection of Apramycin Resistance Genes in Escherichia coli Isolated from Chicken Feces and Houseflies after Apramycin Administration

PubMed Central

Zhang, Anyun; Li, Yunxia; Guan, Zhongbin; Tuo, Hongmei; Liu, Dan; Yang, Yanxian; Xu, Changwen; Lei, Changwei; Wang, Hongning

2018-01-01

The aim of this study was to evaluate the influence of apramycin administration on the development of antibiotic resistance in Escherichia coli (E. coli) strains isolated from chicken feces and houseflies under field conditions. Chickens in the medicated group (n = 25,000) were given successive prophylactic doses (0.5 mg/l) of apramycin in their drinking water from Days 1 to 5, while no antibiotics were added to the un-medicated groups drinking water (n = 25,000). Over 40 days, a total of 1170 E. coli strains were isolated from fecal samples obtained from medicated and un-medicated chickens and houseflies from the same chicken farm. Apramycin MIC90 values for E. coli strains obtained from the medicated group increased 32–128 times from Days 2 to 6 (256–1024 μg/ml) when compared to those on Day 0 (8 μg/ml). Strains isolated from un-medicated chickens and houseflies had consistently low MIC90 values (8–16 μg/ml) during the first week, but showed a dramatic increase from Days 8 to 10 (128–1024 μg/ml). The apramycin resistance gene aac(3)-IV was detected in E. coli strains from medicated (n = 71), un-medicated (n = 32), and housefly groups (n = 42). All strains positive for aac(3)-IV were classified into 12 pulsed-field gel electrophoresis (PFGE) types. PFGE types A, E, and G were the predominant types in both the medicated and housefly groups, suggesting houseflies play an important role in spreading E. coli-resistant strains. Taken together, our study revealed that apramycin administration could facilitate the occurrence of apramycin-resistant E. coli and the apramycin resistance gene acc(3)-IV. In turn, these strains could be transmitted by houseflies, thus increasing the potential risk of spreading multi-drug-resistant E. coli to the public. PMID:29535694

Thermal resistance of Listeria monocytogenes Scott A in ultrafiltered milk as related to the effect of different milk components.

PubMed

Szlachta, Kinga; Keller, Susanne E; Shazer, Arlette; Chirtel, Stuart

2010-11-01

Pasteurization parameters for grade A milk are well established and set by regulation. However, as solids levels increase, an increased amount of heat is required to destroy any pathogens present. This effect is not well characterized. In this work, the effect of increased dairy solids levels on the thermal resistance of Listeria monocytogenes was examined through the use of ultrafiltered (UF) milk, reconstituted milk powder, and the milk components lactose and caseinate. From the results obtained, lactose and caseinate did not appear to affect thermal resistance. In addition, the level of milk fat, up to 10% of the total solids in UF whole milk, did not result in statistically significant changes to thermal resistance when compared with UF skim milk. Reconstituted skim milk powder at 27% total solids (D⁶²-value = 1.16 ± 0.2 [SD] min, z = 5.7) did result in increased thermal resistance, as compared with reconstituted skim milk powder at 17.5% (D⁶²-value = 0.86 ± 0.02 min, z = 5.57) and UF whole milk at 27% total solids (D⁶²-value = 0.66 ± 0.07 min, z = 5.16). However, that increase appeared to be due to the increase in salt levels, not to increases in caseinate, fat, or lactose. Consequently, total solids, as a single measure, could not be used to predict increased thermal resistance of L. monocytogenes in concentrated milk.

Effectiveness of commercial inhibitors against subtype F HIV-1 protease.

PubMed

Krauchenco, Sandra; Martins, Nadia H; Sanches, Mario; Polikarpov, Igor

2009-06-01

Subtype F wild type HIV protease has been kinetically characterized using six commercial inhibitors (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir and saquinavir) commonly used for HIV/AIDS treatment, as well as inhibitor TL-3 and acetyl-pepstatin. We also obtained kinetic parameters for two multi-resistant proteases (one of subtype B and one of subtype F) harboring primary and secondary mutations selected by intensive treatment with ritonavir/nelfinavir. This newly obtained biochemical data shows that all six studied commercially available protease inhibitors are significantly less effective against subtype F HIV proteases than against HIV proteases of subtype B, as judged by increased K(i) and biochemical fitness (vitality) values. Comparison with previously reported kinetic values for subtype A and C HIV proteases show that subtype F wild type proteases are significantly less susceptible to inhibition. These results demonstrate that the accumulation of natural polymorphisms in subtype F proteases yields catalytically more active enzymes with a large degree of cross-resistance, which thus results in strong virus viability.

Gradient boride layers formed by diffusion carburizing and laser boriding

NASA Astrophysics Data System (ADS)

Kulka, M.; Makuch, N.; Dziarski, P.; Mikołajczak, D.; Przestacki, D.

2015-04-01

Laser boriding, instead of diffusion boriding, was proposed to formation of gradient borocarburized layers. The microstructure and properties of these layers were compared to those-obtained after typical diffusion borocarburizing. First method of treatment consists in diffusion carburizing and laser boriding only. In microstructure three zones are present: laser borided zone, hardened carburized zone and carburized layer without heat treatment. However, the violent decrease in the microhardness was observed below the laser borided zone. Additionally, these layers were characterized by a changeable value of mass wear intensity factor thus by a changeable abrasive wear resistance. Although at the beginning of friction the very low values of mass wear intensity factor Imw were obtained, these values increased during the next stages of friction. It can be caused by the fluctuations in the microhardness of the hardened carburized zone (HAZ). The use of through hardening after carburizing and laser boriding eliminated these fluctuations. Two zones characterized the microstructure of this layer: laser borided zone and hardened carburized zone. Mass wear intensity factor obtained a constant value for this layer and was comparable to that-obtained in case of diffusion borocarburizing and through hardening. Therefore, the diffusion boriding could be replaced by the laser boriding, when the high abrasive wear resistance is required. However, the possibilities of application of laser boriding instead of diffusion process were limited. In case of elements, which needed high fatigue strength, the substitution of diffusion boriding by laser boriding was not advisable. The surface cracks formed during laser re-melting were the reason for relatively quickly first fatigue crack. The preheating of the laser treated surface before laser beam action would prevent the surface cracks and cause the improved fatigue strength. Although the cohesion of laser borided carburized layer was sufficient, the diffusion borocarburized layer showed a better cohesion.

Identification of anaerobic threshold by analysis of heart rate variability during discontinuous dynamic and resistance exercise protocols in healthy older men.

PubMed

Simões, Rodrigo Polaquini; Castello-Simões, Viviane; Mendes, Renata Gonçalves; Archiza, Bruno; Dos Santos, Daniel Augusto; Bonjorno, José Carlos; de Oliveira, Claudio Ricardo; Catai, Aparecida Maria; Arena, Ross; Borghi-Silva, Audrey

2014-03-01

The purposes of this study were to determine anaerobic threshold (AT) during discontinuous dynamic and resistive exercise protocols by analysing of heart rate variability (HRV) and blood lactate (BL) in healthy elderly subjects and compare the cardiovascular, metabolic and autonomic variables obtained from these two forms of exercise. Fourteen elderly (70 ± 4 years) apparently healthy males underwent the following tests: (i) incremental ramp test on cycle ergometer, (ii) one repetition maximum (1RM) leg press at 45°, (iii) a discontinuous exercise test on a cycle ergometer (DET-C) protocol and (iv) a resistance exercise leg press (DET-L) protocol. Heart rate, blood pressure and BL were obtained during each increment of exercise intensity. No significant differences (P>0·05) were found between methods of AT determination (BL and HRV) nor the relative intensity corresponding to AT (30% of maximum intensity) between the types of exercise (DET-C and DET-L). Furthermore, no significant differences (P>0·05) were found between the DET-C and DET-L in relation to HRV, however, the DET-L provided higher values of systolic blood pressure and BL (P<0·05) from the intensity corresponding to AT. We conclude that HRV was effective in determination of AT, and the parasympathetic modulation responses obtained during dynamic and resistive exercise protocols were similar when compared at the same relative intensity. However, DET-L resulted in higher values of blood pressure and BL at workloads beyond AT. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Sibutramine and L-carnitine compared to sibutramine alone on insulin resistance in diabetic patients.

PubMed

Derosa, Giuseppe; Maffioli, Pamela; Salvadeo, Sibilla A T; Ferrari, Ilaria; Gravina, Alessia; Mereu, Roberto; D'Angelo, Angela; Palumbo, Ilaria; Randazzo, Sabrina; Cicero, Arrigo F G

2010-01-01

To evaluate the effects of one year of treatment with sibutramine plus L-carnitine compared to sibutramine on body weight, glycemic control, and insulin resistance state in type 2 diabetic patients. Two hundred and fifty-four patients with uncontrolled type 2 diabetes mellitus (T2DM) [glycated hemoglobin (HbA(1c)) >8.0%] in therapy with different oral hypoglycemic agents or insulin were enrolled in this study and randomised to take sibutramine 10 mg plus L-carnitine 2 g or sibutramine 10 mg in monotherapy. We evaluated at baseline, and after 3, 6, 9, and 12 months these parameters: body weight, body mass index (BMI), glycated hemoglobin (HbA(1c)), fasting plasma glucose (FPG), post-prandial plasma glucose (PPG), fasting plasma insulin (FPI), homeostasis model assessment insulin resistance index (HOMA-IR), total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), triglycerides (Tg), retinol binding protein-4 (RBP-4), resistin, visfatin, high sensitivity-C reactive protein (Hs-CRP). There was a decrease in body weight, BMI, HbA(1c), FPI, HOMA-IR, and RBP-4 in both groups, even when the values obtained with sibutramine plus L-carnitine were lower than the values obtained in sibutramine group. There was a faster decrease of FPG, PPG, TC, LDL-C, resistin and Hs-CRP with sibutramine plus L-carnitine even when no differences between the two groups were obtained. Furthermore, only sibutramine plus L-carnitine improved Tg, and visfatin. Sibutramine plus L-carnitine gave a faster improvement of lipid profile, insulin resistance parameters, glycemic control, and body weight compared to sibutramine.

Evaluation of BD MAX Staph SR Assay for Differentiating Between Staphylococcus aureus and Coagulase-Negative Staphylococci and Determining Methicillin Resistance Directly From Positive Blood Cultures.

PubMed

Lee, Jaewoong; Park, Yeon Joon; Park, Dong Jin; Park, Kang Gyun; Lee, Hae Kyung

2017-01-01

We evaluated the performance of the BD MAX StaphSR Assay (SR assay; BD, USA) for direct detection of Staphylococcus aureus and methicillin resistance not only in S. aureus but also in coagulase-negative Staphylococci (CNS) from positive blood cultures. From 228 blood culture bottles, 103 S. aureus [45 methicillin-resistant S. aureus (MRSA), 55 methicillin-susceptible S. aureus (MSSA), 3 mixed infections (1 MRSA+Enterococcus faecalis, 1 MSSA+MRCNS, 1 MSSA+MSCNS)], and 125 CNS (102 MRCNS, 23 MSCNS) were identified by Vitek 2. For further analysis, we obtained the cycle threshold (Ct) values from the BD MAX system software to determine an appropriate cutoff value. For discrepancy analysis, conventional mecA/mecC PCR and oxacillin minimum inhibitory concentrations (MICs) were determined. Compared to Vitek 2, the SR assay identified all 103 S. aureus isolates correctly but failed to detect methicillin resistance in three MRSA isolates. All 55 MSSA isolates were correctly identified by the SR assay. In the concordant cases, the highest Ct values for nuc, mecA, and mec right-extremity junction (MREJ) were 25.6, 22, and 22.2, respectively. Therefore, we selected Ct values from 0-27 as a range of positivity, and applying this cutoff, the sensitivity/specificity of the SR assay were 100%/100% for detecting S. aureus, and 97.9%/98.1% and 99.0%/95.8% for detecting methicillin resistance in S. aureus and CNS, respectively. We propose a Ct cutoff value for nuc/mec assay without considering MREJ because mixed cultures of MSSA and MRCNS were very rare (0.4%) in the positive blood cultures.

Design of a Horizontal Penetrometer for Measuring On-the-Go Soil Resistance

PubMed Central

Topakci, Mehmet; Unal, Ilker; Canakci, Murad; Celik, Huseyin Kursat; Karayel, Davut

2010-01-01

Soil compaction is one of the main negative factors that limits plant growth and crop yield. Therefore, it is important to determine the soil resistance level and map it for the field to find solutions for the negative effects of the compaction. Nowadays, high powered communication technology and computers help us on this issue within the approach of precision agriculture applications. This study is focused on the design of a penetrometer, which can make instantaneous soil resistance measurements in the soil horizontally and data acquisition software based on the GPS (Global Positioning System). The penetrometer was designed using commercial 3D parametric solid modelling design software. The data acquisition software was developed in Microsoft Visual Basic.NET programming language. After the design of the system, manufacturing and assembly of the system was completed and then a field experiment was carried out. According to the data from GPS and penetration resistance values which are collected in Microsoft SQL Server database, a Kriging method by ArcGIS was used and soil resistance was mapped in the field for a soil depth of 40 cm. During operation, no faults, either in mechanical and software parts, were seen. As a result, soil resistance values of 0.2 MPa and 3 MPa were obtained as minimum and maximum values, respectively. In conclusion, the experimental results showed that the designed system works quite well in the field and the horizontal penetrometer is a practical tool for providing on-line soil resistance measurements. This study contributes to further research for the development of on-line soil resistance measurements and mapping within the precision agriculture applications. PMID:22163410

Design of a horizontal penetrometer for measuring on-the-go soil resistance.

PubMed

Topakci, Mehmet; Unal, Ilker; Canakci, Murad; Celik, Huseyin Kursat; Karayel, Davut

2010-01-01

Soil compaction is one of the main negative factors that limits plant growth and crop yield. Therefore, it is important to determine the soil resistance level and map it for the field to find solutions for the negative effects of the compaction. Nowadays, high powered communication technology and computers help us on this issue within the approach of precision agriculture applications. This study is focused on the design of a penetrometer, which can make instantaneous soil resistance measurements in the soil horizontally and data acquisition software based on the GPS (Global Positioning System). The penetrometer was designed using commercial 3D parametric solid modelling design software. The data acquisition software was developed in Microsoft Visual Basic.NET programming language. After the design of the system, manufacturing and assembly of the system was completed and then a field experiment was carried out. According to the data from GPS and penetration resistance values which are collected in Microsoft SQL Server database, a Kriging method by ArcGIS was used and soil resistance was mapped in the field for a soil depth of 40 cm. During operation, no faults, either in mechanical and software parts, were seen. As a result, soil resistance values of 0.2 MPa and 3 MPa were obtained as minimum and maximum values, respectively. In conclusion, the experimental results showed that the designed system works quite well in the field and the horizontal penetrometer is a practical tool for providing on-line soil resistance measurements. This study contributes to further research for the development of on-line soil resistance measurements and mapping within the precision agriculture applications.

Influence of spore moisture content on the dry-heat resistance of Bacillus subtilis var. niger.

PubMed

Angelotti, R; Maryanski, J H; Butler, T F; Peeler, J T; Campbell, J E

1968-05-01

The dry-heat resistance of Bacillus subtilis var. niger spores located in or on various materials was determined as D and z values in the range of 105 through 160 C. The systems tested included spores located on steel and paper strips, spores located between stainless-steel washers mated together under 150 inch-lb and 12 inch-lb of torque, and spores encapsulated in methylmethacrylate and epoxy plastics. D values for a given temperature varied with the test system. High D values were observed for the systems in which spores were encapsulated or under heavy torque, whereas lower D values were observed for the steel and paper strip systems and the lightly torqued system. Similar z values were obtained for the plastic and steel strip systems (z(D) = 21 C), but an unusually low z for spores on paper (z(D) = 12.9 C) and an unusually high z for spores on steel washers mated at 150 inch-lb of torque (z(D) = 32 C) were observed. The effect of spore moisture content on the D value of spores encapsulated in water-impermeable plastic was determined, and maximal resistance was observed for spores with a water activity (a(w)) of 0.2 to 0.4. Significantly decreased D values were observed for spores with moisture contents below a(w) 0.2 or above a(w) 0.4. The data indicate that the important factors to be considered when measuring the dry heat resistance of spores are (i) the initial moisture content of the spore, (ii) the rate of spore desiccation during heating, (iii) the water retention capacity of the material in or on which spores are located, and (iv) the relative humidity of the system at the test temperature.

Optimization of resistant starch formation from high amylose corn starch by microwave irradiation treatments and characterization of starch preparations.

PubMed

Mutlu, Selime; Kahraman, Kevser; Öztürk, Serpil

2017-02-01

The effects of microwave irradiation on resistant starch (RS) formation and functional properties in high-amylose corn starch, Hylon VII, by applying microwave-storing cycles and drying processes were investigated. The Response Surface Methodology (RSM) was used to optimize the reaction conditions, microwave time (2-4min) and power (20-100%), for RS formation. The starch:water (1:10) mixtures were cooked and autoclaved and then different microwave-storing cycles and drying (oven or freeze drying) processes were applied. The RS contents of the samples increased with increasing microwave-storing cycle. The highest RS (43.4%) was obtained by oven drying after 3 cycles of microwave treatment at 20% power for 2min. The F, p (<0.05) and R 2 values indicated that the selected models were consistent. Linear equations were obtained for oven-dried samples applied by 1 and 3 cycles of microwave with regression coefficients of 0.65 and 0.62, respectively. Quadratic equation was obtained for freeze-dried samples applied by 3 cycles of microwave with a regression coefficient of 0.83. The solubility, water binding capacity (WBC) and RVA viscosity values of the microwave applied samples were higher than those of native Hylon VII. The WBC and viscosity values of the freeze-dried samples were higher than those of the oven-dried ones. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis and electrical behavior of Ni-Ti substituted Y-type hexaferrites for high frequency application

NASA Astrophysics Data System (ADS)

Ahmad, Bashir; Ashiq, Muhammad Naeem; Mumtaz, Saleem; Ali, Irshad; Najam-Ul-Haq, Muhmmad; Sadiq, Imran

2018-04-01

This article reports the fabrication of Ni-Ti doped derivatives of Sr2Co2Fe12-2xO22 by economical Sol-gel method. At room temperature X-ray diffraction (XRD) pattern of powder was obtained after sintering at 1050 °C. The XRD analysis revealed the formation of pure Sr-Y hexaferrite phase. It was found that the observed values of dielectric parameters decreased with increasing Ni-Ti substitution. The higher values of dielectric constants and dielectric loss factor at lower frequency were owing to surface charge polarization. In all the samples the resonance peaks were also observed. The observed room temperature DC electrical resistivity found to increase from 1.8x106 to 4.9x109 ohm cm. The observed activation energies values of the fabricated materials are found in 0.52-0.82 eV range. The decrease in dielectric parameters and increase in resistivity of the fabricated samples with substituents suggest these materials have worth application in micro-wave devices as such devices required highly resistive materials.

Genotyping and chlorine-resistance of Methylobacterium aquaticum isolated from water samples in Japan.

PubMed

Furuhata, Katsunori; Banzai, Azusa U; Kawakami, Yasushi; Ishizaki, Naoto; Yoshida, Yoshihiro; Goto, Keiichi; Fukuyama, Masafumi

2011-09-01

For microbial ecological analysis, 14 strains of Methylobacterium aquaticum isolated from water samples were subjected to clustering analysis on the basis of ribotyping and RAPD-PCR tests. The ribopatterns after digestion with EcoRI obtained from 14 strains of M. aquaticum were used to divide the strains into two groups (Groups I and II) with a similarity of 55%. From the analysis of RAPD patterns using primer 208, the 14 strains were divided into 3 groups (A-C) based on a homology of 45% or greater, and from that using primer 272, there were 4 groups (A-D) based on a homology of 50% or greater. The chlorine resistance (99.9% CT values) of these isolates was also experimentally confirmed, and we attempted to define the connection between chlorine resistance and the geno-cluster. The average CT value of group I was 0.89 mg•min/l and the average of group II was 0.69 mg•min/l. No remarkable differences in the CT values for the groups were found.

In vivo assessment of cardiac insulin resistance by nuclear probes using an iodinated tracer of glucose transport.

PubMed

Briat, Arnaud; Slimani, Lotfi; Perret, Pascale; Villemain, Danièle; Halimi, Serge; Demongeot, Jacques; Fagret, Daniel; Ghezzi, Catherine

2007-11-01

Insulin resistance, implying depressed cellular sensitivity to insulin, is a risk factor for type 2 diabetes and cardiovascular disease. This study is the first step towards the development of a technique of insulin resistance measurement in humans with a new tracer of glucose transport, [(123)I]6-deoxy-6-iodo-D-glucose (6DIG). We investigated 6DIG kinetics in anaesthetised control rats and in three models of insulin-resistant rats: fructose fed, Zucker and ZDF. The study of myocardial 6DIG activity was performed under two conditions: first, 6DIG was injected under the baseline condition and then it was injected after a bolus injection of insulin. After each injection, radioactivity was measured over 45 min by external detection via NaI probes, in the heart and blood. A tri-compartment model was developed to obtain fractional transfer coefficients of 6DIG from the blood to the heart. These coefficients were significantly increased with insulin in control rats and did not change significantly in insulin-resistant rats. The ratio of the coefficient obtained under insulin to that obtained under basal conditions gave an index of cardiac insulin resistance for each animal. The mean values of these ratios were significantly lower in insulin-resistant than in control rats: 1.16 +/- 0.06 vs 2.28 +/- 0.18 (p < 0.001) for the fructose-fed group, 0.92 +/- 0.05 vs 1.62 +/- 0.25 (p < 0.01) for the Zucker group and 1.34 +/- 0.06 vs 2.01 +/- 0.26 (p < 0.05) for the ZDF group. These results show that 6DIG could be a useful tracer to image cardiac insulin resistance.

Biocide and antibiotic susceptibility of Salmonella isolates obtained before and after cleaning at six Danish pig slaughterhouses.

PubMed

Gantzhorn, Mette Rørbæk; Pedersen, Karl; Olsen, John Elmerdahl; Thomsen, Line Elnif

2014-07-02

Salmonella sp. continues to be one of the most important foodborne pathogens. Control measures in terms of cleaning and disinfection on food production plants are very important for limiting the risk of contaminated food products to reach the consumer. In the last decade concern has arisen that bacteria exposed to disinfectants can develop resistance toward disinfectants and can have a higher risk of developing antibiotic resistance. The objectives of this study were to examine the prevalence of biocide resistant Salmonella sp. in Danish pig slaughterhouses, to evaluate if there was a correlation between susceptibilities to biocides and antibiotics, and to examine if cleaning and disinfection select isolates with changed susceptibility toward biocides or antibiotics. Salmonella sp. was isolated from the environment in Danish pig slaughterhouses before and after cleaning and disinfection. The susceptibility toward three different biocides, triclosan and two commercial disinfection products: Desinfect Maxi, a quaternary ammonium compound, and Incimaxx DES, an acetic compound, was determined. We found no resistance toward the biocides tested, but we did find that isolates obtained after cleaning had higher minimum inhibitory concentration (MIC) values toward one of the disinfectants (Incimaxx DES) compared to isolates obtained before cleaning and disinfection. This could indicate selection of strains that are more tolerant, due to the cleaning and disinfection. Furthermore, we found that there was a weak statistical correlation between MICs toward the biocides and some antibiotics, but no difference in log(MIC)s toward antibiotics between isolates obtained before and after cleaning, nor did we find any difference in the number of resistances of isolates obtained before and after cleaning and disinfection. Copyright © 2014 Elsevier B.V. All rights reserved.

Antibiotic activity of Emerimicin IV isolated from Emericellopsis minima from Talcahuano Bay, Chile.

PubMed

Inostroza, Alejandro; Lara, Liliana; Paz, Cristian; Perez, Andrés; Galleguillos, Felipe; Hernandez, Victor; Becerra, José; González-Rocha, Gerardo; Silva, Mario

2018-06-01

Due to the increasing emergence of resistance of bacterial pathogens to current antibiotics, we have examined the marine fungi present in sea sediments obtained 200 m offshore to discover new antibacterial compounds active against multidrug-resistant bacteria. One strain, identified as Emericellopsis minima, was isolated from sediments of Talcahuano Bay (Chile). From the liquid culture of E. minima, we isolated Emerimicin IV, a unique fungal peptaibol that exhibited antibacterial activity. The structure of this compound was assigned by interpretation of 1 H NMR and HR-LCMS data. Emerimicin IV showed bacteriostatic activity against clinical isolates of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis with MIC values ranging between 100 and 12.5 μg/mL.

On the difficulties in characterizing ZnO nanowires.

PubMed

Schlenker, E; Bakin, A; Weimann, T; Hinze, P; Weber, D H; Gölzhäuser, A; Wehmann, H-H; Waag, A

2008-09-10

The electrical properties of single ZnO nanowires grown by vapor phase transport were investigated. While some samples were contacted by Ti/Au electrodes, another set of samples was investigated using a manipulator tip in a low energy electron point-source microscope. The deduced resistivities range from 1 to 10(3) Ωcm. Additionally, the resistivities of nanowires from multiple publications were brought together and compared to the values obtained from our measurements. The overview of all data shows enormous differences (10(-3)-10(5) Ωcm) in the measured resistivities. In order to reveal the origin of the discrepancies, the influence of growth parameters, measuring methods, contact resistances, crystal structures and ambient conditions are investigated and discussed in detail.

Intrinsic kinetic parameters of substrate utilization by immobilized anaerobic sludge.

PubMed

Zaiat, M; Vieira, L G; Foresti, E

1997-01-20

This article presents a method for evaluating the intrinsic kinetic parameters of the specific substrate utilization rate (r) equation and discusses the results obtained for anaerobic sludge-bed samples taken from a horizontal-flow anaerobic immobilized sludge (HAIS) reactor. This method utilizes a differential reactor filled with polyurethane foam matrices containing immobilized anaerobic sludge which is subjected to a range of feeding substrate flow rates. The range of liquid superficial velocities thus obtained are used for generating data of observed specific substrate utilization rates (r(obs)) under a diversity of external mass transfer resistance conditions. The r(obs) curves are then adjusted to permit their extrapolation for the condition of no external mass transfer resistance, and the values determined are used as a test for the condition of absence of limitation of internal mass transfer. The intrinsic parameters r(max), the maximum specific substrate utilization rate, and K(s), the half-velocity coefficient, are evaluated from the r values under no external mass transfer resistance and no internal mass transfer limitation. The application of such a method for anaerobic sludge immobilized in polyurethane foam particles treating a glucose substrate at 30 degrees C resulted in intrinsic r(max) and K(s), respectively, of 0.330 mg chemical oxygen demand (COD) . mg(-1) volatile suspended solids (VSS) . h(-1) and 72 mg COD . L(-1). In comparison with the values found in the literature, intrinsic r(max) is significantly high and intrinsic K(s) is relatively low. (c) 1997 John Wiley & Sons, Inc.

Identifying Resistivity Anomalies of Sungai Batu Ancient River using 3D Contour Map

NASA Astrophysics Data System (ADS)

Yusoh, R.; Saad, R.; Saidin, M.; Muhammad, S. B.; Anda, S. T.; Ismail, M. A. M.; Hazreek, Z. A. M.

2018-04-01

Electrical resistivity method was undertaken at archeological site at Sungai Batu in Lembah Bujang, located at Sungai Merbok in northwestern of Malaysia. The survey was implemented near the excavation site. This paper shows the results of 5 ground resistivity survey line was carry out using SAS4000 equipment. The wenner-schlumberger array was applied for measurement. Resistivity data are used to obtain valuable information to identify the remain buried archeology. The ground resistivity data were presented in contour map for various depth by using Surfer 13 software visualized clearly the anomalies evidenced for every single depth section. The results from the survey has found the appearance of sedimentation formation that believe happen long time ago after ancient river was buried by sediment from weathering process due to increasing sea level. Otherwise, another anomaly was found in the middle of the survey area which shows high resistivity value about 1000 – 2000 ohm.m

Self-Test Procedures for Gas Sensors Embedded in Microreactor Systems.

PubMed

Helwig, Andreas; Hackner, Angelika; Müller, Gerhard; Zappa, Dario; Sberveglieri, Giorgio

2018-02-03

Metal oxide (MOX) gas sensors sensitively respond to a wide variety of combustible, explosive and poisonous gases. However, due to the lack of a built-in self-test capability, MOX gas sensors have not yet been able to penetrate safety-critical applications. In the present work we report on gas sensing experiments performed on MOX gas sensors embedded in ceramic micro-reaction chambers. With the help of an external micro-pump, such systems can be operated in a periodic manner alternating between flow and no-flow conditions, thus allowing repetitive measurements of the sensor resistances under clean air, R 0 , and under gas exposure, R g a s , to be obtained, even under field conditions. With these pairs of resistance values, eventual drifts in the sensor baseline resistance can be detected and drift-corrected values of the relative resistance response R e s p = ( R 0 - R g a s ) / R 0 can be determined. Residual poisoning-induced changes in the relative resistance response can be detected by reference to humidity measurements taken with room-temperature-operated capacitive humidity sensors which are insensitive to the poisoning processes operative on heated MOX gas sensors.

Waist circumference and insulin resistance: a cross-sectional study of Japanese men

PubMed Central

Tabata, Shinji; Yoshimitsu, Shinichiro; Hamachi, Tadamichi; Abe, Hiroshi; Ohnaka, Keizo; Kono, Suminori

2009-01-01

Background Visceral obesity is positively related to insulin resistance. The nature of the relationship between waist circumference and insulin resistance has not been known in Japanese populations. This study examined the relationship between waist circumference and insulin resistance and evaluated the optimal cutoff point for waist circumference in relation to insulin resistance in middle-aged Japanese men. Methods Study subjects included 4800 Japanese men aged 39 to 60 years. Insulin resistance was evaluated by the homeostasis model assessment of insulin resistance (HOMA-IR). The relationship of waist circumference with HOMA-IR was assessed by use of adjusted means of HOMA-IR and odds ratios of elevated HOMA-IR defined as the highest quintile (≥2.00). Receiver operating characteristics (ROC) curve analysis using Youden index and the area under curve (AUC) was employed to determine optimal cutoffs of waist circumference in relation to HOMA-IR. Results Adjusted geometric means of HOMA-IR and prevalence odds of elevated HOMA-IR were progressively higher with increasing levels of waist circumference. In the ROC curve analysis, the highest value of Youden index was obtained for a cutoff point of 85 cm in waist circumference across different values of HOMA-IR. Multiple logistic regression analysis also indicated that the AUC was consistently the largest for a waist circumference of 85 cm. Conclusion Waist circumference is linearly related to insulin resistance, and 85 cm in waist circumference is an optimal cutoff in predicting insulin resistance in middle-aged Japanese men. PMID:19138424

Investigation of Sintering Temperature on Attrition Resistance of Highly Porous Diatomite Based Material

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

Garderen, Noemie van; Clemens, Frank J.; Scharf, Dagobert

2010-05-30

Highly porous diatomite based granulates with a diameter of 500 mum have been produced by an extrusion method. In order to investigate the relation between microstructure, phase composition and attrition resistance of the final product, the granulates were sintered between 800 and 1300 deg. C. Mean pore size of the granulates was evaluated by Hg-porosimetry. An increase of the pore size is observed in the range of 3.6 nm to 40 mum with increasing sintering temperature. Higher mean pore radii of 1.6 mum and 5.7 mum obtained by sintering at 800 and 1300 deg. C respectively. X-ray diffraction shows thatmore » mullite phase appears at 1100 deg. C due to the presence of clay. At 1100 deg. C diatomite (amorphous silicate) started to transform into alpha-cristobalite. Attrition resistance was determined by evaluating the amount of ground material passed through a sieve with a predefined mesh size. It was observed that a material sintered at high temperature leads to an increase of attrition resistance due to the decrease of total porosities and phase transformation. Due to the reason that attrition resistance significantly increased by sintering the granulates at higher temperature, a so called attrition resistance index was determined in order to compare all the different attrition resistance values. This attrition resistance index was determined by using the exponential component of the equation obtained from attrition resistance curves. It permits comparison of the attrition behaviour without a time influence.« less

Geothermal Exploration By Using Time Domain IP Method:Balikesir (Gure) And Canakkale (Geyikli) Cases From Turkey

NASA Astrophysics Data System (ADS)

Tezel, O.; Ozcep, F.

2017-12-01

Geothermal energy is heat derived from the earth. It is the thermal energy contained in the rock and fluid (that fills the fractures and pores within the rock) in the earth's crust. These resources are always at a temperature higher than 20°C. Geothermal energy requires no fuel, and is therefore virtually emission free and independent of fluctuations in fuel cost. Since a geothermal power plant doesn't rely on transient sources of energy, unlike, for example, wind turbines or solar panels, its capacity factor can be quite large. Induced polarization (IP) results at geothermal regions show prominent, extended low resistivity zones. Environmental-IP methods can assist in the assessment of the acid generating potential of waste rock and tailings from mine operations. Resistivity can be used to map contamination plumes. Resistivity and chargeability values were determined using the IP method on geothermal resources in Balikesir Güre (Turkey). In this study we found low resistance values and high chargeability values at the geothermal resource. Finally drilling and IP results were correlated to verify our findings. After the positive results of obtained data, a similar study was carried out in Geyikli Area (Canakkale) and a geothermal resource with 450C temperature of 5 lt/sec was explored at a depth of 970 m.

Investigation of the mechanical properties of FeNiCrMnSi high entropy alloy wear resistant

NASA Astrophysics Data System (ADS)

Buluc, G.; Florea, I.; Chelariu, R.; Popescu, G.; Carcea, I.

2016-06-01

In this paper we investigated microstructure, hardness and wear resistance for FeNiCrMnAl, high entropy alloy. The FeNiCrMnSi, high entropy alloy was elaborated in a medium induction furnace, by choosing the silicon, as an alliance element within the equi- atomic high entropy alloy, we managed to obtain a dendritic structure, the formation of intermetallic compounds or separated silicon. The medium hardness value of the investigated alloy was 948.33 HV and the medium value of the friction coefficient was 0.6655 in the first 20 seconds and 0.5425 for 1667 seconds. The volume loss of the high entropy alloy FeNiCrMnSi was 0.0557 mm3.

Measurement of volume resistivity/conductivity of metallic alloy in inhibited seawater by optical interferometry techniques

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

Habib, K.

2011-03-15

Optical interferometry techniques were used for the first time to measure the volume resistivity/conductivity of carbon steel samples in seawater with different concentrations of a corrosion inhibitor. In this investigation, the real-time holographic interferometry was carried out to measure the thickness of anodic dissolved layer or the total thickness, U{sub total}, of formed oxide layer of carbon steel samples during the alternating current (ac) impedance of the samples in blank seawater and in 5-20 ppm TROS C-70 inhibited seawater, respectively. In addition, a mathematical model was derived in order to correlate between the ac impedance (resistance) and the surface (orthogonal)more » displacement of the surface of the samples in solutions. In other words, a proportionality constant [resistivity ({rho}) or conductivity ({sigma})= 1/{rho}] between the determined ac impedance [by electrochemical impedance spectroscopy (EIS) technique] and the orthogonal displacement (by the optical interferometry techniques) was obtained. The value of the resistivity of the carbon steel sample in the blank seawater was found similar to the value of the resistivity of the carbon steel sample air, around 1 x 10{sup -5}{Omega} cm. On the contrary, the measured values of the resistivity of the carbon steel samples were 1.85 x 10{sup 7}, 3.35 x 10{sup 7}, and 1.7 x 10{sup 7}{Omega} cm in 5, 10, and 20 ppm TROS C-70 inhibited seawater solutions, respectively. Furthermore, the determined value range of {rho} of the formed oxide layers, from 1.7 x 10{sup 7} to 3.35 x 10{sup 7}{Omega} cm, is found in a reasonable agreement with the one found in literature for the Fe oxide-hydroxides, i.e., goethite ({alpha}-FeOOH) and for the lepidocrocite ({gamma}-FeOOH), 1 x 10{sup 9}{Omega} cm. The {rho} value of the Fe oxide-hydroxides, 1 x 10{sup 9}{Omega} cm, was found slightly higher than the {rho} value range of the formed oxide layer of the present study. This is because the former value was determined by a dc method rather than by an electromagnetic method, i.e., holographic interferometry with applications of EIS, i.e., ac method. As a result, erroneous measurements were recorded due to the introduction of heat to Fe oxide-hydroxides.« less

Water content estimated from point scale to plot scale

NASA Astrophysics Data System (ADS)

Akyurek, Z.; Binley, A. M.; Demir, G.; Abgarmi, B.

2017-12-01

Soil moisture controls the portioning of rainfall into infiltration and runoff. Here we investigate measurements of soil moisture using a range of techniques spanning different spatial scales. In order to understand soil water content in a test basin, 512 km2 in area, in the south of Turkey, a Cosmic Ray CRS200B soil moisture probe was installed at elevation of 1459 m and an ML3 ThetaProbe (CS 616) soil moisture sensor was established at 5cm depth used to get continuous soil moisture. Neutron count measurements were corrected for the changes in atmospheric pressure, atmospheric water vapour and intensity of incoming neutron flux. The calibration of the volumetric soil moisture was performed, from the laboratory analysis, the bulk density varies between 1.719 (g/cm3) -1.390 (g/cm3), and the dominant soil texture is silty clay loam and silt loamThe water content reflectometer was calibrated for soil-specific conditions and soil moisture estimates were also corrected with respect to soil temperature. In order to characterize the subsurface, soil electrical resistivity tomography was used. Wenner and Schlumberger array geometries were used with electrode spacing varied from 1m- 5 m along 40 m and 200 m profiles. From the inversions of ERT data it is apparent that within 50 m distance from the CRS200B, the soil is moderately resistive to a depth of 2m and more conductive at greater depths. At greater distances from the CRS200B, the ERT results indicate more resistive soils. In addition to the ERT surveys, ground penetrating radar surveys using a common mid-point configuration was used with 200MHz antennas. The volumetric soil moisture obtained from GPR appears to overestimate those based on TDR observations. The values obtained from CS616 (at a point scale) and CRS200B (at a mesoscale) are compared with the values obtained at a plot scale. For the field study dates (20-22.06.2017) the volumetric moisture content obtained from CS616 were 25.14%, 25.22% and 25.96% respectively. The values obtained from CRS200B were 23.23%, 22.81% and 23.26% for the same dates. Whereas the values obtained from GPR were between 32%-44%. Soil moisture observed by CRS200B is promising to monitor the water content in the soil at the mesoscale and ERT surveys help to understand the spatial variability of the soil water content within the footprint of CRS200B.

Note: A non-invasive electronic measurement technique to measure the embedded four resistive elements in a Wheatstone bridge sensor

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

Ravelo Arias, S. I.; Ramírez Muñoz, D.; Cardoso, S.

2015-06-15

The work shows a measurement technique to obtain the correct value of the four elements in a resistive Wheatstone bridge without the need to separate the physical connections existing between them. Two electronic solutions are presented, based on a source-and-measure unit and using discrete electronic components. The proposed technique brings the possibility to know the mismatching or the tolerance between the bridge resistive elements and then to pass or reject it in terms of its related common-mode rejection. Experimental results were taken in various Wheatstone resistive bridges (discrete and magnetoresistive integrated bridges) validating the proposed measurement technique specially when themore » bridge is micro-fabricated and there is no physical way to separate one resistive element from the others.« less

A new rapid colourimetric method for testing Mycobacterium tuberculosis susceptibility to isoniazid and rifampicin: a crystal violet decolourisation assay.

PubMed

Coban, Ahmet Yilmaz

2014-04-01

The aim of this study was to investigate the performance of a new and accurate method for the detection of isoniazid (INH) and rifampicin (RIF) resistance among Mycobacterium tuberculosis isolates using a crystal violet decolourisation assay (CVDA). Fifty-five M. tuberculosis isolates obtained from culture stocks stored at -80ºC were tested. After bacterial inoculation, the samples were incubated at 37ºC for seven days and 100 µL of CV (25 mg/L stock solution) was then added to the control and sample tubes. The tubes were incubated for an additional 24-48 h. CV (blue/purple) was decolourised in the presence of bacterial growth; thus, if CV lost its colour in a sample containing a drug, the tested isolate was reported as resistant. The sensitivity, specificity, positive predictive value, negative predictive value and agreement for INH were 92.5%, 96.4%, 96.1%, 93.1% and 94.5%, respectively, and 88.8%, 100%, 100%, 94.8% and 96.3%, respectively, for RIF. The results were obtained within eight-nine days. This study shows that CVDA is an effective method to detect M. tuberculosis resistance to INH and RIF in developing countries. This method is rapid, simple and inexpensive. Nonetheless, further studies are necessary before routine laboratory implementation.

Structure and properties of corrosion and wear resistant Cr-Mn-N steels

NASA Astrophysics Data System (ADS)

Lenel, U. R.; Knott, B. R.

1987-06-01

Steels containing about 12 pct Cr, 10 pct Mn, and 0.2 pct N have been shown to have an unstable austenitic microstructure and have good ductility, extreme work hardening, high fracture strength, excellent toughness, good wear resistance, and moderate corrosion resistance. A series of alloys containing 9.5 to 12.8 pct Cr, 5.0 to 10.4 pct Mn, 0.16 to 0.32 pct N, 0.05 pct C, and residual elements typical of stainless steels was investigated by microstructural examination and mechanical, abrasion, and corrosion testing. Microstructures ranged from martensite to unstable austenite. The unstable austenitic steels transformed to α martensite on deformation and displayed very high work hardening, exceeding that of Hadfield’s manganese steels. Fracture strengths similar to high carbon martensitic stainless steels were obtained while ductility and toughness values were high, similar to austenitic stainless steels. Resistance to abrasive wear exceeded that of commercial abrasion resistant steels and other stainless steels. Corrosion resistance was similar to that of other 12 pct Cr steels. Properties were not much affected by minor compositional variations or rolled-in nitrogen porosity. In 12 pct Cr-10 pct Mn alloys, ingot porosity was avoided when nitrogen levels were below 0.19 pet, and austenitic microstructures were obtained when nitrogen levels exceeded 0.14 pct.

The zeta potential of extended dielectrics and conductors in terms of streaming potential and streaming current measurements.

PubMed

Gallardo-Moreno, Amparo M; Vadillo-Rodríguez, Virginia; Perera-Núñez, Julia; Bruque, José M; González-Martín, M Luisa

2012-07-21

The electrical characterization of surfaces in terms of the zeta potential (ζ), i.e., the electric potential contributing to the interaction potential energy, is of major importance in a wide variety of industrial, environmental and biomedical applications in which the integration of any material with the surrounding media is initially mediated by the physico-chemical properties of its outer surface layer. Among the different existing electrokinetic techniques for obtaining ζ, streaming potential (V(str)) and streaming current (I(str)) are important when dealing with flat-extended samples. Mostly dielectric materials have been subjected to this type of analysis and only a few papers can be found in the literature regarding the electrokinetic characterization of conducting materials. Nevertheless, a standardized procedure is typically followed to calculate ζ from the measured data and, importantly, it is shown in this paper that such a procedure leads to incorrect zeta potential values when conductors are investigated. In any case, assessment of a reliable numerical value of ζ requires careful consideration of the origin of the input data and the characteristics of the experimental setup. In particular, it is shown that the cell resistance (R) typically obtained through a.c. signals (R(a.c.)), and needed for the calculations of ζ, always underestimates the zeta potential values obtained from streaming potential measurements. The consideration of R(EK), derived from the V(str)/I(str) ratio, leads to reliable values of ζ when dielectrics are investigated. For metals, the contribution of conductivity of the sample to the cell resistance provokes an underestimation of R(EK), which leads to unrealistic values of ζ. For the electrical characterization of conducting samples I(str) measurements constitute a better choice. In general, the findings gathered in this manuscript establish a measurement protocol for obtaining reliable zeta potentials of dielectrics and conductors based on the intrinsic electrokinetic behavior of both types of samples.

In vitro pharmacokinetics of antimicrobial cationic peptides alone and in combination with antibiotics against methicillin resistant Staphylococcus aureus biofilms.

PubMed

Dosler, Sibel; Mataraci, Emel

2013-11-01

Antibiotic therapy for methicillin-resistant Staphylococcus aureus (MRSA) infections is becoming more difficult in hospitals and communities because of strong biofilm-forming properties and multidrug resistance. Biofilm-associated MRSA is not affected by therapeutically achievable concentrations of antibiotics. Therefore, we investigated the in vitro pharmacokinetic activities of antimicrobial cationic peptides (AMPs; indolicidin, cecropin [1-7]-melittin A [2-9] amide [CAMA], and nisin), either alone or in combination with antibiotics (daptomycin, linezolid, teicoplanin, ciprofloxacin, and azithromycin), against standard and 2 clinically obtained MRSA biofilms. The minimum inhibitory concentrations (MIC) and minimum biofilm-eradication concentrations (MBEC) were determined by microbroth dilution technique. The time-kill curve (TKC) method was used to determine the bactericidal activities of the AMPs alone and in combination with the antibiotics against standard and clinically obtained MRSA biofilms. The MIC values of the AMPs and antibiotics ranged between 2 to 16 and 0.25 to 512 mg/L, and their MBEC values were 640 and 512 to 5120 mg/L, respectively. The TKC studies demonstrated that synergistic interactions occurred most frequently when using nisin+daptomycin/ciprofloxacin, indolicidin+teicoplanin, and CAMA+ciprofloxacin combinations. No antagonism was observed with any combination. AMPs appear to be good candidates for the treatment of MRSA biofilms, as they act as both enhancers of anti-biofilm activities and help to prevent or delay the emergence of resistance when used either alone or in combination with antibiotics. Copyright © 2013 Elsevier Inc. All rights reserved.

Near-surface high resolution imaging of a metallogenic zone in the northern fringe of Dalma volcanics in eastern India using electrical resistivity tomography

NASA Astrophysics Data System (ADS)

Adhikari, P. K.; Srivastava, Shalivahan; Maurya, Ved P.; Tripathi, Anurag; Singh, Roshan K.; Bage, Ashish K.

2017-06-01

Electrical resistivity tomography (ERT) is a useful tool to map near-surface conducting anomalies. The detailed ERT survey was taken over an already defined conducting zone on a regional scale through a magnetotelluric (MT) survey, in order to provide better resolution of the subsurface structure within the study area. The survey lines were carried out crossing the delineated conducting zone through MT giving a dense coverage over the area. The ERT survey were carried out along 15 lines covering an area of ~1 km2 with a line spacing of ~50 m in the northern fringe of the Dalma volcanics (DVs). The study utilised the 61-channel cum 64-electrode resistivity equipment, FlashRES-Universal ERT multi-electrode data acquisition system, developed by ZZ Resistivity Imaging, Australia. Data has been acquired both through conventional arrays i.e. Wenner, Schlumberger and ZZ unconventional arrays. Inversion of the data set have been performed using 2.5D finite element conjugate gradient algorithm after performing the quality check. Resistivity models along all the lines were obtained using Wenner, Schlumberger and combination of Wenner, Schlumberger and ZZ arrays. Resistivity models resolved four major zones: (1) resistivity less than 1 Ωm (2) resistivity 1-10 Ωm (3) resistivity 10-100 Ωm and (4) resistivity more than 100 Ωm . The resistivity results corroborate well with the geological succession from the drilling data. The conducting zones with resistivity values ranging from 1-10 Ωm correlates with the Lower Dalma volcanics while the Upper Dalma volcanics corresponds to the regions with resistivity values of less than 1 Ωm. The Upper Dalma volcanics corresponds to the metallogeny while the depth to the top of the ore body is ~25 m.

Simulation and measurement of nanometer-scale resistivity of copper films for interconnect applications

NASA Astrophysics Data System (ADS)

Yarimbiyik, Arif Emre

2007-12-01

A highly versatile simulation program is developed and used to examine how the resistivity of thin metal films and lines increases as their dimensions approach and become smaller than the mean fee path of electrons in metals such as copper (size effect). The simulation program: (1) provides a more accurate calculation of surface scattering effects than that obtained from the usual formulation of Fuchs' theory, (2) calculates grain-boundary effects that are consistent with the theory of Mayadas and Shatzkes, (3) includes the effects of surface and grain-boundary scattering either separately or together, and (4) simulates the effect on resistivity if a surface of a film or line has a different value for the scattering parameter. The increase in resistivity with decreasing thickness of thin, evaporated copper films (approximately 10 nm to 150 nm thick) was determined from sheet resistance and film thickness measurements. Good agreement between the experimental results with those of the simulation program was obtained when the measured mean grain sizes were used by the simulation program. The mean of the grain sizes tend to decrease with decreasing film thickness and thereby increase the impact of grain-boundary scattering on the effective resistivity of the film. Estimates of the mean grain size for each film were determined from using, in combination, the electron backscatter diffraction (EBSD) and the X-ray diffraction (XRD) methods. With values for the measured change in sheet resistance with temperature of these films, it is shown that measurements of the electrical film thickness, using Matthiessen's rule, agreed to within 3 nm of the physical measurements (profilometer) of these films. Hence, Matthiessen's rule can continue to be used to measure the thickness of a copper film and, by inference, the cross-sectional area of a copper line for dimensions well below the mean free path of electrons in copper at room temperature (39 nm).

Electrochemical testing of suspension plasma sprayed solid oxide fuel cell electrolytes

NASA Astrophysics Data System (ADS)

Waldbillig, D.; Kesler, O.

Electrochemical performance of metal-supported plasma sprayed (PS) solid oxide fuel cells (SOFCs) was tested for three nominal electrolyte thicknesses and three electrolyte fabrication conditions to determine the effects of electrolyte thickness and microstructure on open circuit voltage (OCV) and series resistance (R s). The measured OCV values were approximately 90% of the Nernst voltages, and electrolyte area specific resistances below 0.1 Ω cm 2 were obtained at 750 °C for electrolyte thicknesses below 20 μm. Least-squares fitting was used to estimate the contributions to R s of the YSZ bulk material, its microstructure, and the contact resistance between the current collectors and the cells. It was found that the 96% dense electrolyte layers produced from high plasma gas flow rate conditions had the lowest permeation rates, the highest OCV values, and the smallest electrolyte-related voltage losses. Optimal electrolyte thicknesses were determined for each electrolyte microstructure that would result in the lowest combination of OCV loss and voltage loss due to series resistance for operating voltages of 0.8 V and 0.7 V.

The imaging study of a novel photopolymer used in I-line negative-tone resist

NASA Astrophysics Data System (ADS)

Liu, Lu; Zou, Yingquan

2010-04-01

By copolymerization of 2-(2-diazo-3-oxo-3-(4-dimethylaminophenyl)propionyloxy)ethyl methacrylate (DODMAPPEA), methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA), a photoactive polymer for negative-tone resist is synthesized and its photolithographic properties are investigated. Since the maximum-absorption wavelength of the photoactive monomer DODMAPPEA is 356nm and it still has a comparatively large absorption at 365nm (I-line), the copolymer poly(DODMAPPEA -co-MMA-co-HEMA) is anticipated to be used in I-line single component negative-tone resist. Upon irradiaton, the diazoketo groups which are in the side chains of the copolymers undergo the wolff rearrangement, affording ketenes that react with hydroxyl to provide cross-linking photoproducts and a negative image is obtained. Besides that, cross-linking agent hexamethoxymethylmelamine (HMMM) is added to the resist system and high sensitivity is expected. This kind of copolymer has great value in I-line non-CARs, TFT-LCD and IC discrete devices processing and the anti-dry etching ability is enhanced by the introduction of the benzene ring. In addition, this copolymer still has potential value in Ultra-violate lithographic plate.

Machine Learning to Improve the Effectiveness of ANRS in Predicting HIV Drug Resistance.

PubMed

Singh, Yashik

2017-10-01

Human immunodeficiency virus infection and acquired immune deficiency syndrome (HIV/AIDS) is one of the major burdens of disease in developing countries, and the standard-of-care treatment includes prescribing antiretroviral drugs. However, antiretroviral drug resistance is inevitable due to selective pressure associated with the high mutation rate of HIV. Determining antiretroviral resistance can be done by phenotypic laboratory tests or by computer-based interpretation algorithms. Computer-based algorithms have been shown to have many advantages over laboratory tests. The ANRS (Agence Nationale de Recherches sur le SIDA) is regarded as a gold standard in interpreting HIV drug resistance using mutations in genomes. The aim of this study was to improve the prediction of the ANRS gold standard in predicting HIV drug resistance. A genome sequence and HIV drug resistance measures were obtained from the Stanford HIV database (http://hivdb.stanford.edu/). Feature selection was used to determine the most important mutations associated with resistance prediction. These mutations were added to the ANRS rules, and the difference in the prediction ability was measured. This study uncovered important mutations that were not associated with the original ANRS rules. On average, the ANRS algorithm was improved by 79% ± 6.6%. The positive predictive value improved by 28%, and the negative predicative value improved by 10%. The study shows that there is a significant improvement in the prediction ability of ANRS gold standard.

Optical and Electrical Properties of Tin-Doped Cadmium Oxide Films Prepared by Electron Beam Technique

NASA Astrophysics Data System (ADS)

Ali, H. M.; Mohamed, H. A.; Wakkad, M. M.; Hasaneen, M. F.

2009-04-01

Tin-doped cadmium oxide films were deposited by electron beam evaporation technique. The structural, optical and electrical properties of the films were characterized. The X-ray diffraction (XRD) study reveals that the films are polycrystalline in nature. As composition and structure change due to the dopant ratio and annealing temperature, the carrier concentration was varied around 1020 cm-3, and the mobility increased from less than 10 to 45 cm2 V-1 s-1. A transmittance value of ˜83% and a resistivity value of 4.4 ×10-4 Ω cm were achieved for (CdO)0.88(SnO2)0.12 film annealed at 350 °C for 15 min., whereas the maximum value of transmittance ˜93% and a resistivity value of 2.4 ×10-3 Ω cm were obtained at 350 °C for 30 min. The films exhibited direct band-to-band transitions, which corresponded to optical band gaps of 3.1-3.3 eV.

Correlation between electrical direct current resistivity and plasmonic properties of CMOS compatible titanium nitride thin films.

PubMed

Viarbitskaya, S; Arocas, J; Heintz, O; Colas-Des-Francs, G; Rusakov, D; Koch, U; Leuthold, J; Markey, L; Dereux, A; Weeber, J-C

2018-04-16

Damping distances of surface plasmon polariton modes sustained by different thin titanium nitride (TiN) films are measured at the telecom wavelength of 1.55 μm. The damping distances are correlated to the electrical direct current resistivity of the films sustaining the surface plasmon modes. It is found that TiN/Air surface plasmon mode damping distances drop non-linearly from 40 to 16μm as the resistivity of the layers increases from 28 to 130μΩ.cm, respectively. The relevance of the direct current (dc) electrical resistivity for the characterization of TiN plasmonic properties is investigated in the framework of the Drude model, on the basis of parameters extracted from spectroscopic ellipsometry experiments. By probing a parametric space of realistic values for parameters of the Drude model, we obtain a nearly univocal dependence of the surface plasmon damping distance on the dc resistivity demonstrating the relevance of dc resistivity for the evaluation of the plasmonic performances of TiN at telecom frequencies. Finally, we show that better plasmonic performances are obtained for TiN films featuring a low content of oxygen. For low oxygen content and corresponding low resistivity, we attribute the increase of the surface plasmon damping distances to a lower confinement of the plasmon field into the metal and not to a decrease of the absorption of TiN.

SUPPLEMENTARY COMPARISON: APMP.EM-S6: Bilateral supplementary comparison of resistance

NASA Astrophysics Data System (ADS)

Charoensook, Ajchara; Jassadajin, Chaiwat; Chen, Henry; Ricketts, Brian

2004-01-01

A bilateral supplementary comparison of resistance, APMP.EM-S6, was conducted between the National Institute of Metrology Thailand (NIMT) and the CSIRO National Measurement Laboratory of Australia (NML). The comparison covered seven values of resistance, 0.1 Ω, 1 Ω, 100 Ω, 10 kΩ, 100 kΩ, 1 MΩ and 100 MΩ. The 0.1 Ω resistor was a YEW type 2792, the 100 MΩ resistor was an IET type SRC and the other five resistors were Fluke type 742A. The resistors were supplied by NIMT, and NML was the pilot laboratory for the comparison. The measurements for the comparison were made between December 2003 and April 2004. The resistors were measured on three separate occasions by NIMT and between each of these occasions the resistors were sent to NML for measurement. The resistors of nominal values 0.1 Ω, 1 Ω, 100 Ω and 10 kΩ were measured as four-terminal resistors while the 100 kΩ, 1 MΩ and 100 MΩ resistors were measured as two-terminal resistors. The quantity En (the absolute value of the difference between the values obtained at the two laboratories divided by the root sum square of the expanded uncertainties of the two values) was calculated for each resistance value used in the comparison. In all cases En was less than 0.5. 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 APMP, according to the provisions of the Mutual Recognition Arrangement (MRA).

Antimicrobial susceptibilities and molecular typing of neisseria gonorrhoeae isolates at a medical centre in Taiwan, 2001-2013 with an emphasis on high rate of azithromycin resistance among the isolates.

PubMed

Liu, Yen-Hung; Huang, Yu-Tsung; Liao, Chun-Hsing; Hsueh, Po-Ren

2018-05-01

A high prevalence of gonococcal resistance to various antimicrobials and Neisseria gonorrhoeae isolates exhibiting resistance to extended-spectrum cephalosporins have been reported in the past few decades. A total of 226 N. gonorrhoeae isolates obtained from the National Taiwan University Hospital from 2001 to 2013 were evaluated. The minimum inhibitory concentrations (MICs) of the isolates to antimicrobials were determined by the agar dilution method and interpreted using the 2017 clinical breakpoints or epidemiological cut-off values recommended by the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST). The genetic relatedness of these isolates was determined by multilocus sequence typing. None of the isolates was resistant to ceftriaxone and cefotaxime, and the resistance rates to cefixime, spectinomycin, cefpodoxime, ciprofloxacin, and penicillin were 0.4%, 0.4%, 13.3%, 91.6%, and 87.6%, respectively. The rate of isolates resistant to azithromycin was 14.6% (EUCAST criteria), which is higher than in previous surveillance studies. A total of 57 sequence types (ST) were identified, and ST1901, ST7365, and ST1927 prevailed. Isolates of ST8143 emerged after 2011. ST1901 isolates had relatively higher MIC values for ceftriaxone and azithromycin than those of the other STs. In conclusion, ceftriaxone remains an effective drug of choice for gonorrhoeal management in Taiwan. High rates of azithromycin resistance among N. gonorrhoeae isolates were found. The circulating ST1901 strains with high MIC values for ceftriaxone and azithromycin and the emerging ST8143 strains were alarming. Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Phytochemical Screening and Antimicrobial Activity of Some Medicinal Plants Against Multi-drug Resistant Bacteria from Clinical Isolates

PubMed Central

Dahiya, Praveen; Purkayastha, Sharmishtha

2012-01-01

The in vitro antibacterial activity of various solvents and water extracts of aloe vera, neem, bryophyllum, lemongrass, tulsi, oregano, rosemary and thyme was assessed on 10 multi-drug resistant clinical isolates from both Gram-positive and Gram-negative bacteria and two standard strains including Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922. The zone of inhibition as determined by agar well diffusion method varied with the plant extract, the solvent used for extraction, and the organism tested. Klebsiella pneumoniae 2, Escherichia coli 3 and Staphylococcus aureus 3 were resistant to the plant extracts tested. Moreover, water extracts did not restrain the growth of any tested bacteria. Ethanol and methanol extracts were found to be more potent being capable of exerting significant inhibitory activities against majority of the bacteria investigated. Staphylococcus aureus 1 was the most inhibited bacterial isolate with 24 extracts (60%) inhibiting its growth whereas Escherichia coli 2 exhibited strong resistance being inhibited by only 11 extracts (28%). The results obtained in the agar diffusion plates were in fair correlation with that obtained in the minimum inhibitory concentration tests. The minimum inhibitory concentration of tulsi, oregano, rosemary and aloe vera extracts was found in the range of 1.56-6.25 mg/ml for the multi-drug resistant Staphylococcus aureus isolates tested whereas higher values (6.25-25 mg/ml) were obtained against the multi-drug resistant isolates Klebsiella pneumoniae 1 and Escherichia coli 1 and 2. Qualitative phytochemical analysis demonstrated the presence of tannins and saponins in all plants tested. Thin layer chromatography and bioautography agar overlay assay of ethanol extracts of neem, tulsi and aloe vera indicated flavonoids and tannins as major active compounds against methicillin-resistant Staphylococcus aureus. PMID:23716873

A new concept for stainless steels ranking upon the resistance to cavitation erosion

NASA Astrophysics Data System (ADS)

Bordeasu, I.; Popoviciu, M. O.; Salcianu, L. C.; Ghera, C.; Micu, L. M.; Badarau, R.; Iosif, A.; Pirvulescu, L. D.; Podoleanu, C. E.

2017-01-01

In present, the ranking of materials as their resistance to cavitation erosion is obtained by using laboratory tests finalized with the characteristic curves mean depth erosion against time MDE(t) and mean depth erosion rate against time MDER(t). In some previous papers, Bordeasu and co-workers give procedures to establish exponential equation representing the curves, with minimum scatter of the experimental obtained results. For a given material, both exponential equations MDE(t) and MDER(t) have the same values for the parameters of scale and for the shape one. For the ranking of materials is sometimes important to establish single figure. Till now in Timisoara Polytechnic University Cavitation Laboratory were used three such numbers: the stable value of the curve MDER(t), the resistance to cavitation erosion (Rcav ≡ 1/MDERstable) and the normalized cavitation resistance Rns which is the rate between vs = MDERstable for the analyzed material and vse= MDERse the mean depth erosion rate for the steel OH12NDL (Rns = vs/vse ). OH12NDL is a material used for manufacturing the blades of numerous Kaplan turbines in Romania for which both cavitation erosion laboratory tests and field measurements of cavitation erosions are available. In the present paper we recommend a new method for ranking the materials upon cavitation erosion resistance. This method uses the scale and shape parameters of the exponential equations which represents the characteristic cavitation erosion curves. Till now the method was applied only for stainless steels. The experimental results show that the scale parameter represents an excellent method for ranking the stainless steels. In the future this kind of ranking will be tested also for other materials especially for bronzes used for manufacturing ship propellers.

Individualised second line anti-tuberculous therapy for an extensively resistant pulmonary tuberculosis (XDR PTB) in East Malaysia.

PubMed

Muhammad Redzwan, S R A; Ralph, A P; Sivaraman Kannan, K K; William, T

2015-06-01

Clinical experience with extensively Drug Resistant tuberculosis (XDR-TB) has not been reported in Malaysia before. We describe the clinical characteristics, risk factors, progress and therapeutic regimen for a healthcare worker with XDR-TB, who had failed therapy for multidrug resistant TB (MDR TB) in our institution. This case illustrates the risk of TB among healthcare workers in high TB-burden settings, the importance of obtaining upfront culture and susceptibility results in all new TB cases, the problem of acquired drug resistance developing during MDR-TB treatment, the challenges associated with XDR-TB treatment regimens, the value of surgical resection in refractory cases, and the major quality of life impact this disease can have on young, economically productive individuals.

Transfer and expression of the rabbit defensin NP-1 gene in lettuce (Lactuca sativa).

PubMed

Song, D; Xiong, X; Tu, W F; Yao, W; Liang, H W; Chen, F J; He, Z Q

2017-01-23

Lettuce (Lactuca sativa L.) is an annual plant of the daisy family, Asteraceae, with high food and medicinal value. However, the crop is susceptible to several viruses that are transmitted by aphids and is highly vulnerable to post-harvest diseases, as well as insect and mammal pests and fungal and bacterial diseases. Here, the rabbit defensin gene NP-1 was transferred into lettuce by Agrobacterium-mediated transformation to obtain a broad-spectrum disease-resistant lettuce. Transgenic lettuce plants were selected and regenerated on selective media. The presence of the NP-1 gene in these plants was confirmed by western blot analyses. Resistance tests revealed native defensin NP-1 expression conferred partial resistance to Bacillus subtilis and Pseudomonas aeruginosa, which suggests new possibilities for lettuce disease resistance.

In vitro antileukaemic activity of extracts from chokeberry (Aronia melanocarpa [Michx] Elliott) and mulberry (Morus alba L.) leaves against sensitive and multidrug resistant HL60 cells.

PubMed

Skupień, Katarzyna; Kostrzewa-Nowak, Dorota; Oszmiański, Jan; Tarasiuk, Jolanta

2008-05-01

The aim of the present study was to determine in vitro antileukaemic activities of extracts obtained from chokeberry (Aronia melanocarpa [Michx] Elliot) and mulberry (Morus alba L.) leaves against promyelocytic HL60 cell line and its multidrug resistant sublines exhibiting two different MDR phenotypes: HL60/VINC (overexpressing P-glycoprotein) and HL60/DOX (overexpressing MRP1 protein). It was found that the extracts from chokeberry and mulberry leaves were active against the sensitive leukaemic cell line HL60 and retained the in vitro activity against multidrug resistant sublines (HL60/VINC and HL60/DOX). The values of resistance factor (RF) found for these extracts were very low lying in the range 1.2-1.6.

Changes in tissue water and indentation resistance of lymphedematous limbs accompanying low level laser therapy (LLLT) of fibrotic skin.

PubMed

Mayrovitz, H N; Davey, S

2011-12-01

Our goal was to determine effects of low-level-laser-therapy (LLLT) on skin water and tissue indentation resistance (TIR) in patients with arm (N = 38) or leg (N = 38) lymphedema. Skin water was determined from tissue dielectric constant (TDC) measurements and TIR determined from measurements of force resulting from tissue indentations of 3-4 mm. A limb-location with fibrosis was identified by palpation and treated with an LLLT device for one minute at each of five points within a 3 cm2 area. TDC and TIR at these sites and corresponding sites on the contralateral limb were measured prior to LLLT (pre-LLLT), immediately after LLLT (post-LLLT) and after a manual lymphatic drainage (MLD) session (post-MLD). Results, from arms and legs, showed that post-LLLT values of TIR and TDC were significantly less than pre-LLLT. TIR values remained significantly reduced at post-MLD whereas TDC values were not significantly different from pre-LLLT values. On follow-up visit, 17 previously LLLT treated legs were sham treated with an inactive LLLT unit and measurements replicated. A TIR and TDC change-pattern similar to that obtained with the active LLLT was obtained, but sham-related reductions in TIR and TDC immediately post sham-treatment were significantly less than achieved with the prior active LLLT treatment.

Electrochemical stability and corrosion resistance of Ti-Mo alloys for biomedical applications.

PubMed

Oliveira, N T C; Guastaldi, A C

2009-01-01

Electrochemical behavior of pure Ti and Ti-Mo alloys (6-20wt.% Mo) was investigated as a function of immersion time in electrolyte simulating physiological media. Open-circuit potential values indicated that all Ti-Mo alloys studied and pure Ti undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the chloride-containing solution. It also indicated that the addition of Mo to pure Ti up to 15wt.% seems to improve the protection characteristics of its spontaneous oxides. Electrochemical impedance spectroscopy (EIS) studies showed high impedance values for all samples, increasing with immersion time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film present on the metals' surface, improving their resistance with immersion time, presenting the highest values to Ti-15Mo alloy. Potentiodynamic polarization showed a typical valve-metal behavior, with anodic formation of barrier-type oxide films, without pitting corrosion, even in chloride-containing solution. In all cases, the passive current values were quite small, and decrease after 360h of immersion. All these electrochemical results suggest that the Ti-15Mo alloy is a promising material for orthopedic devices, since electrochemical stability is directly associated with biocompatibility and is a necessary condition for applying a material as biomaterial.

Biased four-point probe resistance

NASA Astrophysics Data System (ADS)

Garcia-Vazquez, Valentin

2017-11-01

The implications of switching the current polarity in a four-point probe resistance measurement are presented. We demonstrate that, during the inversion of the applied current, any change in the voltage V produced by a continuous drop of the sample temperature T will induce a bias in the temperature-dependent DC resistance. The analytical expression for the bias is deduced and written in terms of the variations of the measured voltages with respect to T and by the variations of T with respect to time t. Experimental data measured on a superconducting Nb thin film confirm that the bias of the normal-state resistance monotonically increases with the cooling rate dT/dt while keeping fixed dV/dT; on the other hand, the bias increases with dV/dT, reaching values up to 13% with respect to the unbiased resistance obtained at room temperature.

Corrosion sensor for monitoring the service condition of chloride-contaminated cement mortar.

PubMed

Lu, Shuang; Ba, Heng-Jing

2010-01-01

A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (Rp) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (Rs). The results show that the polarization resistance is related to the chloride content and Rs; ln (Rp) is linearly related to the Rs values in mortar without added chloride. The relationships observed between the Rp of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that Rs can indicate the corrosion state of concrete structures.

Thermal boundary resistance between the end of an individual carbon nanotube and a Au surface.

PubMed

Hirotani, Jun; Ikuta, Tatsuya; Nishiyama, Takashi; Takahashi, Koji

2011-08-05

The thermal boundary resistance between an individual carbon nanotube and a Au surface was measured using a microfabricated hot-film sensor. We used both closed and open-ended multi-walled carbon nanotubes and obtained thermal boundary resistance values of 0.947-1.22 × 10(7) K W(-1) and 1.43-1.76 × 10(7) K W(-1), respectively. Considering all uncertainties, including the contact area, the thermal boundary conductances per unit area were calculated to be 8.6 × 10(7)-2.2 × 10(8) W m(-2) K(-1) for c-axis orientation and 4.2 × 10(8)-1.2 × 10(9) W m(-2) K(-1) for the a-axis. The trend in these values agrees with the predicted conductance dependence on the interface orientation of anisotropic carbon-based materials. However, the measured thermal boundary conductances are found to be much larger than the reported results.

Investigation of anticorrosion properties of nanocomposites of spray coated zinc oxide and titanium dioxide thin films on stainless steel (304L SS) in saline environment

NASA Astrophysics Data System (ADS)

P, Muhamed Shajudheen V.; S, Saravana Kumar; V, Senthil Kumar; Maheswari A, Uma; M, Sivakumar; Rani K, Anitha

2018-01-01

The present study reports the anticorrosive nature of nanocomposite thin films of zinc oxide and titanium dioxide on steel substrate (304L SS) using spray coating method. The morphology and chemical constituents of the nanocomposite thin film were characterized by field effect scanning electron microscopy and energy dispersive analysis of x-ray (EDAX) studies. From the EDAX studies, it was observed that nanocomposite coatings of desired stoichiometry can be synthesized using present coating technique. The cyclic voltametric techniques such as Tafel analysis and electrochemical impedance spectroscopy (EIS) analysis were conducted to study the anticorrosion properties of the coatings. The E corr values obtained from Tafel polarization curves of the sample coated with nanocomposites of ZnO and TiO2 in different ratios (5:1, 1:1 and 1:5) indicated that the corrosion resistance was improved compared to bare steel. The coating resistance values obtained from the Nyquist plot after fitting with equivalent circuit confirmed the improved anticorrosion performance of the coated samples. The sample coated with ZnO: TiO2 in the ratio 1:5 showed better corrosion resistance compared to other ratios. The Tafel and EIS studies were repeated after exposure to 5% NaCl for 390 h and the results indicated the anticorrosive nature of the coating in the aggressive environment. The root mean square deviation of surface roughness values calculated from the AFM images before and after salt spray indicated the stability of coating in the saline environment.

A novel real-time data acquisition using an Excel spreadsheet in pendulum experiment tool with light-based timer

NASA Astrophysics Data System (ADS)

Adhitama, Egy; Fauzi, Ahmad

2018-05-01

In this study, a pendulum experimental tool with a light-based timer has been developed to measure the period of a simple pendulum. The obtained data was automatically recorded in an Excel spreadsheet. The intensity of monochromatic light, sensed by a 3DU5C phototransistor, dynamically changes as the pendulum swings. The changed intensity varies the resistance value and was processed by the microcontroller, ATMega328, to obtain a signal period as a function of time and brightness when the pendulum crosses the light. Through the experiment, using calculated average periods, the gravitational acceleration value has been accurately and precisely determined.

Pulse mode of operation of a spherical piezoceramic transducer filled with liquid and having a correcting electric circuit.

PubMed

Konovalov, S I; Kuz'menko, A G

2010-12-01

By means of a computational method, the possibility of radiating a short acoustic pulse by a transducer in the form of a piezoceramic sphere internally filled with liquid is investigated. An electric inductive-resistive circuit is connected to the electric input of the transducer. Solution is obtained based on scheme-analogs theory for piezoceramic transducers, and spectral Fourier transform theory. The values of parameters of the system, providing minimal durations of radiated signals, are determined. Computation was carried out for different values of relative thicknesses of the transducer wall. The estimates of durations and amplitudes of the acoustic signals radiated into the external medium are obtained.

Characterization of a Newly Developed Contrast Enhancement Material for G-line Exposure

NASA Astrophysics Data System (ADS)

Nakase, Makoto; Niki, Hirokazu; Satoh, Takashi; Kumagae, Akitoshi

1987-02-01

The bleaching characteristics for a contrast enhancement layer (CEL) material were succesfully described by parameters A, B and C; these were used for the modeling of a positive photoresist exposure. As a result, it was clarified that both the A and C values should be large, but the B value must be as small as possible. According to the obtained information, a new CEL material was proposed, which consists of the diazonium compound and the alkyl modified phenol resin. Using the composed CEL material, a submicron resist pattern with a steep profile was obtained. Furthermore, it was found that the development latitude increases, but that the exposure latitude does not change upon using the CEL.

Genotyping and rifampicin and isoniazid resistance in Mycobacterium bovis strains isolated from the lymph nodes of slaughtered cattle.

PubMed

Franco, Marília Masello Junqueira; Ribeiro, Márcio Garcia; Pavan, Fernando Rogério; Miyata, Marcelo; Heinemann, Marcos Bryan; de Souza Filho, Antonio Francisco; Cardoso, Rosilene Fressatti; de Almeida, Aryadne Larissa; Sakate, Ricardo Ichiro; Paes, Antonio Carlos

2017-05-01

In developing nations, 10-20% of the human cases of tuberculosis are caused by Mycobacterium bovis. However, this percentage may be underestimated because most laboratories in developing countries do not routinely perform mycobacterial cultures, and only a few have the systems in place to identify M. bovis. There are few studies investigating genotypic diversity and drug resistance in M. bovis from animal and/or human infections. The genotypic diversity of M. bovis strains obtained from bovine lymph nodes were investigated by spacer oligonucleotide typing (spoligotyping) and mycobacterial interspersed repetitive unit-variable-number tandem repeat typing (MIRU-VNTR). The phenotypic resistance to isoniazid and rifampicin and MIC values of the isolates were determined using the resazurin microtiter assay plate method (REMA). The evaluation of the possible genetic basis for such resistance was performed with GenoType MTBDRplus. Sixty-seven isolates were obtained, of which 11 (16%) were MDR-TB, 8 (12%) were isoniazid-resistant, and 2 (3%) were rifampicin-resistant. Mutations associated with drug resistance were not found. Genotyping techniques enabled the grouping of the strains into 12 clusters and 21 isolates with unique profiles. The high frequency of M. bovis reinforces the impact of the pathogen as a major causal agent of bovine tuberculosis in the study area. The resistance of the strains to drugs used for first-line treatment of human tuberculosis raises public health concerns. Further studies are required to elucidate the basis of drug resistance and genotypic diversity in M. bovis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of hydroxyapatite on the corrosion resistance of the Ti-13Nb-13Zr alloy.

PubMed

Duarte, Laís T; Biaggio, Sonia R; Rocha-Filho, Romeu C; Bocchi, Nerilso

2009-05-01

Electrochemical analyses on the biocompatible alloy Ti-13Nb-13Zr wt% in an electrolyte simulating physiological medium (PBS solution) are reported. Hydroxyapatite (HA) films were obtained on the alloy by electrodeposition at constant cathodic current. Samples of the alloy covered with an anodic-oxide film or an anodic-oxide/HA film were analyzed by open circuit potential and electrochemical impedance spectroscopy measurements during 180 days in the PBS electrolyte. Analyses of the open-circuit potential (E (oc)) values indicated that the oxide/HA film presents better protection characteristics than the oxide only. This behavior was corroborated by the higher film resistances obtained from impedance data, indicating that, besides improving the alloy osteointegration, the hydroxyapatite film may also increase the corrosion protection of the biomaterial.

Friction and Surface Damage of Several Corrosion-resistant Materials

NASA Technical Reports Server (NTRS)

Peterson, Marshall B; Johnson, Robert L

1952-01-01

Friction and surface damage of several materials that are resistant to corrosion due to liquid metals was studied in air. The values of kinetic friction coefficient at low sliding velocities and photomicrographs of surface damage were obtained. Appreciable surface damage was evident for all materials tested. The friction coefficients for the combinations of steel, stainless steel, and monel sliding against steel, stainless steel, nickel, Iconel, and Nichrome ranged from 0.55 for the monel-Inconel combination to 0.97 for the stainless-steel-nickel combination; for steel, stainless steel, monel, and tungsten carbide against zirconium, the friction coefficient was approximately 0.47. Lower coefficients of friction (0.20 to 0.60) and negligible surface failure at light loads were obtained with tungsten carbide when used in combination with various plate materials.

Global strong solutions to the one-dimensional heat-conductive model for planar non-resistive magnetohydrodynamics with large data

NASA Astrophysics Data System (ADS)

Li, Yang

2018-06-01

In this paper, we consider the initial-boundary value problem to the one-dimensional compressible heat-conductive model for planar non-resistive magnetohydrodynamics. By making full use of the effective viscous flux and an analogue, together with the structure of the equations, global existence and uniqueness of strong solutions are obtained on condition that the initial density is bounded below away from vacuum and the heat conductivity coefficient κ satisfies the growth condition κ _1(1+θ^{α })≤ κ (θ)≤ κ _2(1+θ^{α }),\\quad { for some }0< α < ∞, with κ _1,κ _2 being positive constants. Moreover, global solvability of strong solutions is shown with the initial vacuum. The results are obtained without any smallness restriction to the initial data.

Ship Trim Optimization: Assessment of Influence of Trim on Resistance of MOERI Container Ship

PubMed Central

Duan, Wenyang

2014-01-01

Environmental issues and rising fuel prices necessitate better energy efficiency in all sectors. Shipping industry is a stakeholder in environmental issues. Shipping industry is responsible for approximately 3% of global CO2 emissions, 14-15% of global NOX emissions, and 16% of global SOX emissions. Ship trim optimization has gained enormous momentum in recent years being an effective operational measure for better energy efficiency to reduce emissions. Ship trim optimization analysis has traditionally been done through tow-tank testing for a specific hullform. Computational techniques are increasingly popular in ship hydrodynamics applications. The purpose of this study is to present MOERI container ship (KCS) hull trim optimization by employing computational methods. KCS hull total resistances and trim and sinkage computed values, in even keel condition, are compared with experimental values and found in reasonable agreement. The agreement validates that mesh, boundary conditions, and solution techniques are correct. The same mesh, boundary conditions, and solution techniques are used to obtain resistance values in different trim conditions at Fn = 0.2274. Based on attained results, optimum trim is suggested. This research serves as foundation for employing computational techniques for ship trim optimization. PMID:24578649

The Influence of Specimen Type on Tensile Fracture Toughness of Rock Materials

NASA Astrophysics Data System (ADS)

Aliha, Mohammad Reza Mohammad; Mahdavi, Eqlima; Ayatollahi, Majid Reza

2017-03-01

Up to now, several methods have been proposed to determine the mode I fracture toughness of rocks. In this research, different cylindrical and disc shape samples, namely: chevron bend (CB), short rod (SR), cracked chevron notched Brazilian disc (CCNBD), and semi-circular bend (SCB) specimens were considered for investigating mode I fracture behavior of a marble rock. It is shown experimentally that the fracture toughness values of the tested rock material obtained from different test specimens are not consistent. Indeed, depending on the geometry and loading type of the specimen, noticeable discrepancies can be observed for the fracture toughness of a same rock material. The difference between the experimental mode I fracture resistance results is related to the magnitude and sign of T-stress that is dependent on the geometry and loading configuration of the specimen. For the chevron-notched samples, the critical value of T-stress corresponding to the critical crack length was determined using the finite element method. The CCNBD and SR specimens had the most negative and positive T-stress values, respectively. The dependency of mode I fracture resistance to the T-stress was shown using the extended maximum tangential strain (EMTSN) criterion and the obtained experimental rock fracture toughness data were predicted successfully with this criterion.

Performance of High-frequency High-flux Magnetic Cores at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Gerber, Scott S.; Hammoud, Ahmad; Elbuluk, Malik E.; Patterson, Richard L.

2002-01-01

Three magnetic powder cores and one ferrite core, which are commonly used in inductor and transformer design for switch mode power supplies, were selected for investigation at cryogenic temperatures. The powder cores are Molypermalloy Core (MPC), High Flux Core (HFC), and Kool Mu Core (KMC). The performance of four inductors utilizing these cores has been evaluated as a function of temperature from 20 C to -180 C. All cores were wound with the same wire type and gauge to obtain equal values of inductance at room temperature. Each inductor was evaluated in terms of its inductance, quality (Q) factor, resistance, and dynamic hysteresis characteristics (B-H loop) as a function of temperature and frequency. Both sinusoidal and square wave excitations were used in these investigations. Measured data obtained on the inductance showed that both the MPC and the HFC cores maintain a constant inductance value, whereas with the KMC and ferrite core hold a steady value in inductance with frequency but decrease as temperature is decreased. All cores exhibited dependency, with varying degrees, in their quality factor and resistance on test frequency and temperature. Except for the ferrite, all cores exhibited good stability in the investigated properties with temperature as well as frequency. Details of the experimental procedures and test results are presented and discussed in the paper.

Cyantraniliprole: a valuable tool for Frankliniella occidentalis (Pergande) management.

PubMed

Bielza, Pablo; Guillén, Juan

2015-08-01

Frankliniella occidentalis is a worldwide economically important pest. Scarcity of effective products and cross-resistance issues make resistance to existing insecticides a recurring problem that requires the development of new control tools, such as incorporating novel compounds. Lethal effects of cyantraniliprole on adults and larvae from field and insecticide-resistant populations were evaluated. In addition, the sublethal effects on biological features such as fecundity, fertility, feeding, oviposition and mating were studied. Results obtained for larvae produced LC50 values ranging from 33.4 to 109.2 mg L(-1) , with a low natural variability (3.3-fold) and a LC50 composite value of 52.2 mg L(-1) . The susceptibility for adults was 23-fold lower than for larvae. No evidence of cross-resistance between cyantraniliprole and established insecticides used against thrips was evident. Relevant sublethal effects of cyantraniliprole were demonstrated, including reduced fecundity, fertility, feeding, oviposition and mating success. Low variation in susceptibility across contemporary populations of F. occidentalis and a lack of cross-resistance to other insecticides indicate that cyantraniliprole is a potential candidate in rotation programmes within an insecticide resistance management strategy. The combined sublethal effect on reproduction will have an important impact on population reduction. Available data indicate that cyantraniliprole is likely to be a valuable tool for managing thrips populations. © 2014 Society of Chemical Industry.

Evaluating conducting network based transparent electrodes from geometrical considerations

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

Kumar, Ankush; Kulkarni, G. U., E-mail: guk@cens.res.in

2016-01-07

Conducting nanowire networks have been developed as viable alternative to existing indium tin oxide based transparent electrode (TE). The nature of electrical conduction and process optimization for electrodes have gained much from the theoretical models based on percolation transport using Monte Carlo approach and applying Kirchhoff's law on individual junctions and loops. While most of the literature work pertaining to theoretical analysis is focussed on networks obtained from conducting rods (mostly considering only junction resistance), hardly any attention has been paid to those made using template based methods, wherein the structure of network is neither similar to network obtained frommore » conducting rods nor similar to well periodic geometry. Here, we have attempted an analytical treatment based on geometrical arguments and applied image analysis on practical networks to gain deeper insight into conducting networked structure particularly in relation to sheet resistance and transmittance. Many literature examples reporting networks with straight or curvilinear wires with distributions in wire width and length have been analysed by treating the networks as two dimensional graphs and evaluating the sheet resistance based on wire density and wire width. The sheet resistance values from our analysis compare well with the experimental values. Our analysis on various examples has revealed that low sheet resistance is achieved with high wire density and compactness with straight rather than curvilinear wires and with narrower wire width distribution. Similarly, higher transmittance for given sheet resistance is possible with narrower wire width but of higher thickness, minimal curvilinearity, and maximum connectivity. For the purpose of evaluating active fraction of the network, the algorithm was made to distinguish and quantify current carrying backbone regions as against regions containing only dangling or isolated wires. The treatment can be helpful in predicting the properties of a network simply from image analysis and will be helpful in improvisation and comparison of various TEs and better understanding of electrical percolation.« less

Evaluating conducting network based transparent electrodes from geometrical considerations

NASA Astrophysics Data System (ADS)

Kumar, Ankush; Kulkarni, G. U.

2016-01-01

Conducting nanowire networks have been developed as viable alternative to existing indium tin oxide based transparent electrode (TE). The nature of electrical conduction and process optimization for electrodes have gained much from the theoretical models based on percolation transport using Monte Carlo approach and applying Kirchhoff's law on individual junctions and loops. While most of the literature work pertaining to theoretical analysis is focussed on networks obtained from conducting rods (mostly considering only junction resistance), hardly any attention has been paid to those made using template based methods, wherein the structure of network is neither similar to network obtained from conducting rods nor similar to well periodic geometry. Here, we have attempted an analytical treatment based on geometrical arguments and applied image analysis on practical networks to gain deeper insight into conducting networked structure particularly in relation to sheet resistance and transmittance. Many literature examples reporting networks with straight or curvilinear wires with distributions in wire width and length have been analysed by treating the networks as two dimensional graphs and evaluating the sheet resistance based on wire density and wire width. The sheet resistance values from our analysis compare well with the experimental values. Our analysis on various examples has revealed that low sheet resistance is achieved with high wire density and compactness with straight rather than curvilinear wires and with narrower wire width distribution. Similarly, higher transmittance for given sheet resistance is possible with narrower wire width but of higher thickness, minimal curvilinearity, and maximum connectivity. For the purpose of evaluating active fraction of the network, the algorithm was made to distinguish and quantify current carrying backbone regions as against regions containing only dangling or isolated wires. The treatment can be helpful in predicting the properties of a network simply from image analysis and will be helpful in improvisation and comparison of various TEs and better understanding of electrical percolation.

[Reliability of HOMA-IR for evaluation of insulin resistance during perioperative period].

PubMed

Fujino, Hiroko; Itoda, Shoko; Sako, Saori; Matsuo, Kazuki; Sakamoto, Eiji; Yokoyama, Takeshi

2013-02-01

Hyperglycemia due to increase in insulin resistance (IR) is often observed after surgery in spite of normal insulin secretion. To evaluate the degree of IR, the golden standard method is the normoglycemic hyperinsulinemic clamp technique (glucose clamp: GC). The GC using the artificial pancreas, STG-22 (Nikkiso, Tokyo, Japan), was established as a more reliable method, since it was evaluated during steady-state period under constant insulin infusion. Homeostasis model assessment insulin resistance (HOMA-IR), however, is frequently employed in daily practice because of its convenience. We, therefore, investigated the reliability of HOMA-IR in comparison with the glucose clamp using the STG-22. Eight healthy patients undergoing maxillofacial surgery were employed in this study after obtaining written informed consent. Their insulin resistance was evaluated by HOMA-IR and the GC using the STG-22 before and after surgery. HOMA-IR increased from 0.81 +/- 0.48 to 1.17 +/- 0.50, although there were no significant differences between before and after surgery. On the other hand, M-value by GC significantly decreased after surgery from 8.82 +/- 2.49 mg x kg(-1) x min(-1) to 3.84 +/- 0.79 mg x kg(-1) x min(-1) (P = 0.0003). In addition, no significant correlation was found between the values of HOMA-IR and the M-value by GC. HOMA-IR may not be reliable to evaluate IR for perioperative period.

Effect of sintering process and additives on the properties of cordierite based ceramics

NASA Astrophysics Data System (ADS)

Rundans, M.; Sperberga, I.; Sedmale, G.; Stinkulis, G.

2013-12-01

It is possible to obtain cordierite ceramics with high temperature synthesis using both synthetic and raw natural materials. This paper discusses the possibilities to obtain cordierite ceramics, replacing part of required oxides with raw materials from various Latvian deposits of dolomite and clay. The obtained raw cordierite powders were ground in two modes (3 and 12 hours) and fired at 1200 °C. Ceramic samples were characterized by hydrostatic weighting method; crystalline phase composition was studied by XRD. Obtained samples were evaluated by their mechanical (compressive) strength and linear coefficient of thermal expansion (CTE). Thermal shock resistance was tested using water quenching method and afterwards evaluated by using ultrasonic method to test changes in Young's modulus of elasticity. Results show that increase in grinding time causes samples to densify and promote formation of cordierite crystalline phase which corresponds to increase in total compressive strength and decrease of CTE values. CTE values of samples ground for 12 hours conform to that of obtained in other researches.

Modeling of electric and heat processes in spot resistance welding of cross-wire steel bars

NASA Astrophysics Data System (ADS)

Iatcheva, Ilona; Darzhanova, Denitsa; Manilova, Marina

2018-03-01

The aim of this work is the modeling of coupled electric and heat processes in a system for spot resistance welding of cross-wire reinforced steel bars. The real system geometry, dependences of material properties on the temperature, and changes of contact resistance and released power during the welding process have been taken into account in the study. The 3D analysis of the coupled AC electric and transient thermal field distributions is carried out using the finite element method. The novel feature is that the processes are modeled for several successive time stages, corresponding to the change of contact area, related contact resistance, and reduction of the released power, occurring simultaneously with the creation of contact between the workpieces. The values of contact resistance and power changes have been determined on the basis of preliminary experimental and theoretical investigations. The obtained results present the electric and temperature field distributions in the system. Special attention has been paid to the temperature evolution at specified observation points and lines in the contact area. The obtained information could be useful for clarification of the complicated nature of interrelated electric, thermal, mechanical, and physicochemical welding processes. Adequate modeling is also an opportunity for proper control and improvement of the system.

Insulin-sensitive obese children display a favorable metabolic profile.

PubMed

Vukovic, Rade; Mitrovic, Katarina; Milenkovic, Tatjana; Todorovic, Sladjana; Soldatovic, Ivan; Sipetic-Grujicic, Sandra; Zdravkovic, Dragan

2013-02-01

Most of what is known about the metabolically healthy obese phenomenon is derived from studies in the adult population and no standardized criteria to identify these individuals exist to date. The aim of this study was to determine if the preserved insulin sensitivity evaluated by homeostatic model assessment of insulin resistance (HOMA-IR) index is associated with favorable metabolic profile in the obese children. We studied a group of 248 children and adolescents (150 female, 98 male), aged 5.9-18.9 years with diet-induced obesity (BMI >95th percentile). The entire cohort was divided into quartiles based on levels of insulin resistance determined by HOMA-IR index. Subjects in the lower quartile of HOMA-IR were classified as insulin-sensitive group (ISG), whereas children in the upper quartile were categorized as insulin-resistant group (IRG). The ISG subjects had values of HOMA-IR ≤2.75 while the children from the IRG group had HOMA-IR ≥6.16. Subjects from ISG group had lower basal β-cell activity and were less likely to have impaired fasting glucose or impaired glucose tolerance. Concentrations of LDL and total cholesterol, triglycerides, and transaminases were lower and HDL cholesterol levels were higher in ISG subjects. Findings obtained by the use of Matsuda index correlated well with the findings obtained by the use of HOMA-IR. Lower HOMA-IR values were significantly associated with favorable metabolic profile in studied children, which correlates with findings in the adult population and emphasizes the need for further, longitudinal studies of insulin resistance development in childhood obesity.

The theoretical relationship between foliage temperature and canopy resistance in sparse crops

NASA Technical Reports Server (NTRS)

Shuttleworth, W. James; Gurney, Robert J.

1990-01-01

One-dimensional, sparse-crop interaction theory is reformulated to allow calculation of the canopy resistance from measurements of foliage temperature. A submodel is introduced to describe eddy diffusion within the canopy which provides a simple, empirical simulation of the reported behavior obtained from a second-order closure model. The sensitivity of the calculated canopy resistance to the parameters and formulas assumed in the model is investigated. The calculation is shown to exhibit a significant but acceptable sensitivity to extreme changes in canopy aerodynamics, and to changes in the surface resistance of the substrate beneath the canopy at high and intermediate values of leaf area index. In very sparse crops changes in the surface resistance of the substrate are shown to contaminate the calculated canopy resistance, tending to amplify the apparent response to changes in water availability. The theory is developed to allow the use of a measurement of substrate temperature as an option to mitigate this contamination.

Resistive switching characteristics of interfacial phase-change memory at elevated temperature

NASA Astrophysics Data System (ADS)

Mitrofanov, Kirill V.; Saito, Yuta; Miyata, Noriyuki; Fons, Paul; Kolobov, Alexander V.; Tominaga, Junji

2018-04-01

Interfacial phase-change memory (iPCM) devices were fabricated using W and TiN for the bottom and top contacts, respectively, and the effect of operation temperature on the resistive switching was examined over the range between room temperature and 200 °C. It was found that the high-resistance (RESET) state in an iPCM device drops sharply at around 150 °C to a low-resistance (SET) state, which differs by ˜400 Ω from the SET state obtained by electric-field-induced switching. The iPCM device SET state resistance recovered during the cooling process and remained at nearly the same value for the RESET state. These resistance characteristics greatly differ from those of the conventional Ge-Sb-Te (GST) alloy phase-change memory device, underscoring the fundamentally different switching nature of iPCM devices. From the thermal stability measurements of iPCM devices, their optimal temperature operation was concluded to be less than 100 °C.

Magnetic resonance imaging and electromyography as indexes of muscle function

NASA Technical Reports Server (NTRS)

Adams, Gregory R.; Duvoisin, Marc R.; Dudley, Gary A.

1992-01-01

A hypothesis is tested that exercise-induced magnetic resonance (MR) contrast shifts would relate to electromyography (EMG) amplitude if both measures reflect muscle use during exercise. Both magnetic resonance images (MRI) and EMG data were obtained for separate eccentric (ECC) and cocentric (CON) exercise of increasing intensity for seven subjects 30-32 yr old. CON and ECC actions caused increased integrated EMG (IEMG) and T2 values which were strongly related with relative resistance. The rate of increase and absolute value of both T2 and IEMG were found to be greater for CON than for ECC actions. For both actions IEMG and T2 were correlated. Data obtained suggest that surface IEMG accurately reflects the contractile behavior of muscle and exercise-induced increases in MRI T2 values reflect certain processes that scale with muscle use.

Electrical, structural and morphological properties of chemically sprayed F-doped ZnO films: effect of the ageing-time of the starting solution, solvent and substrate temperature

NASA Astrophysics Data System (ADS)

Guillén-Santiago, A.; Olvera, M. De La L.; Maldonado, A.; Asomoza, R.; Acosta, D. R.

2004-04-01

Conductive and highly transparent fluorine-doped zinc oxide (ZnO:F) thin films were deposited onto glass substrates by the chemical spray technique, using zinc acetate and hydrofluoric acid as precursors. Electrical, structural, morphological and optical characteristics were analyzed as a function of the ageing-time of the starting solution, alcoholic solvent type (methanol or ethanol) and the substrate temperature. The results show that these variables play a crucial role on the physical properties measured. The growth rates obtained were of 3 nm/s, showing that the chemical species involved are adequate for the film growth. The effect of the solution ageing-time on the electrical properties was monitored along three weeks. A gradual resistivity decrease with the ageing-time was observed, until a minimum value is reached, at 7 or 9 days depending on the alcohol employed. Films deposited after this time have resistivity values slightly higher. All the films were polycrystalline, with a hexagonal wurtzite structure whose preferential growth is strongly dependent on the deposition variables. Under optimal deposition conditions, ZnO:F films with a high transmittance in the visible spectrum (>85%), resistivity as low as 7 × 10-3 cm and maximum electronic mobility around of 4 cm2/(V-s) were obtained.

Discerning apical and basolateral properties of HT-29/B6 and IPEC-J2 cell layers by impedance spectroscopy, mathematical modeling and machine learning.

PubMed

Schmid, Thomas; Bogdan, Martin; Günzel, Dorothee

2013-01-01

Quantifying changes in partial resistances of epithelial barriers in vitro is a challenging and time-consuming task in physiology and pathophysiology. Here, we demonstrate that electrical properties of epithelial barriers can be estimated reliably by combining impedance spectroscopy measurements, mathematical modeling and machine learning algorithms. Conventional impedance spectroscopy is often used to estimate epithelial capacitance as well as epithelial and subepithelial resistance. Based on this, the more refined two-path impedance spectroscopy makes it possible to further distinguish transcellular and paracellular resistances. In a next step, transcellular properties may be further divided into their apical and basolateral components. The accuracy of these derived values, however, strongly depends on the accuracy of the initial estimates. To obtain adequate accuracy in estimating subepithelial and epithelial resistance, artificial neural networks were trained to estimate these parameters from model impedance spectra. Spectra that reflect behavior of either HT-29/B6 or IPEC-J2 cells as well as the data scatter intrinsic to the used experimental setup were created computationally. To prove the proposed approach, reliability of the estimations was assessed with both modeled and measured impedance spectra. Transcellular and paracellular resistances obtained by such neural network-enhanced two-path impedance spectroscopy are shown to be sufficiently reliable to derive the underlying apical and basolateral resistances and capacitances. As an exemplary perturbation of pathophysiological importance, the effect of forskolin on the apical resistance of HT-29/B6 cells was quantified.

The relationship of geophysical measurements to engineering and construction parameters in the Straight Creek Tunnel pilot bore, Colorado

USGS Publications Warehouse

Scott, J.H.; Lee, F.T.; Carroll, R.D.; Robinson, C.S.

1968-01-01

Seismic-refraction and electrical-resistivity measurements made along the walls of the Straight Creek Tunnel pilot bore indicate that both a low-velocity and a high-resistivity layer exist in the disturbed rock surrounding the excavation. Seismic measurements were analyzed to obtain the thickness and seismic velocity of rock in the low-velocity layer, the velocity of rock behind the layer and the amplitude of seismic energy received at the detectors. Electrical-resistivity measurements were analyzed to obtain the thickness and electrical resistivity of the high-resistivity layer and the resistivity of rock behind the layer. The electrical resistivity and the seismic velocity of rock at depth, the thickness of rock in the low-velocity layer, and the relative amplitude of seismic energy were correlated against the following parameters, all of which are important in tunnel construction: height of the tension arch, stable vertical rock load, rock quality, rate of construction and cost per foot, percentage of lagging and blocking, set spacing, and type and amount of steel support required, The correlations were statistically meaningful, having correlation coefficients ranging in absolute value from about 0??7 to nearly 1??0. This finding suggests the possibility of predicting parameters of interest in tunnel construction from geophysical measurements made in feeler holes drilled ahead of a working face. Predictions might be based on correlations established either during the early stages of construction or from geophysical surveys in other tunnels of similar design in similar geologic environments. ?? 1968.

Cytotoxic Activity of Extracts from Plants of Central Argentina on Sensitive and Multidrug-Resistant Leukemia Cells: Isolation of an Active Principle from Gaillardia megapotamica

PubMed Central

González, María Laura; Joray, Mariana Belén; Laiolo, Jerónimo; Crespo, María Inés; Palacios, Sara María; Ruiz, Gustavo Miguel

2018-01-01

Plants are a significant reservoir of cytotoxic agents, including compounds with the ability to interfere with multidrug-resistant (MDR) cells. With the aim of finding promising candidates for chemotherapy, 91 native and naturalized plants collected from the central region of Argentina were screened for their cytotoxic effect toward sensitive and MDR P-glycoprotein (P-gp) overexpressing human leukemia cells by means of MTT assays. The ethanol extracts obtained from Aldama tucumanensis, Ambrosia elatior, Baccharis artemisioides, Baccharis coridifolia, Dimerostemma aspilioides, Gaillardia megapotamica, and Vernonanthura nudiflora presented outstanding antiproliferative activity at 50 μg/mL, with inhibitory values from 93 to 100%, when tested on the acute lymphoblastic leukemia (ALL) cell line CCRF-CEM and the resistant derivative CEM-ADR5000, while 70–90% inhibition was observed against the chronic myelogenous leukemia (CML) cell K562 and its corresponding resistant subline, Lucena 1. Subsequent investigation showed these extracts to possess marked cytotoxicity with IC50 values ranging from 0.37 to 29.44 μg/mL, with most of them being below 7 μg/mL and with ALL cells, including the drug-resistant phenotype, being the most affected. G. megapotamica extract found to be one of the most effective and bioguided fractionation yielded helenalin (1). The sesquiterpene lactone displayed IC50 values of 0.63, 0.19, 0.74, and 0.16 μg/mL against K562, CCRF-CEM, Lucena 1, and CEM/ADR5000, respectively. These results support the potential of these extracts as a source of compounds for treating sensitive and multidrug-resistant leukemia cells and support compound 1 as a lead for developing effective anticancer agents. PMID:29861776

Transferable Drug Resistance in Pseudomonas aeruginosa1

PubMed Central

Bryan, L. E.; Elzen, H. M. Van Den; Tseng, Jui Teng

1972-01-01

Three strains of Pseudomonas aeruginosa were demonstrated to transfer double-drug resistance by conjugation to a P. aeruginosa recipient at frequencies of 10−4 to 10−2 per recipient cell. Two of the three strains also transferred to Escherichia coli at frequencies which were 103- to 105-fold lower, but the third strain could not be demonstrated to do so. The latter strain, however, conferred maleness on the Pseudomonas recipient. The transfer of streptomycin resistance was associated with the acquisition of streptomycin phosphorylase by both P. aeruginosa and E. coli recipients. Maximal broth mating frequencies were obtained with nonagitated cultures less than 1 mm in depth. A pyocine selection system based on donor sensitivity and recipient resistance is described and appears to have future value as a generalized selective device for use after matings. PMID:4207756

The electrical properties of 60 keV zinc ions implanted into semi-insulating gallium arsenide

NASA Technical Reports Server (NTRS)

Littlejohn, M. A.; Anikara, R.

1972-01-01

The electrical behavior of zinc ions implanted into chromium-doped semiinsulating gallium arsenide was investigated by measurements of the sheet resistivity and Hall effect. Room temperature implantations were performed using fluence values from 10 to the 12th to 10 to the 15th power/sq cm at 60 keV. The samples were annealed for 30 minutes in a nitrogen atmosphere up to 800 C in steps of 200 C and the effect of this annealing on the Hall effect and sheet resistivity was studied at room temperature using the Van der Pauw technique. The temperature dependence of sheet resistivity and mobility was measured from liquid nitrogen temperature to room temperature. Finally, a measurement of the implanted profile was obtained using a layer removal technique combined with the Hall effect and sheet resistivity measurements.

Influence of Spore Moisture Content on the Dry-Heat Resistance of Bacillus subtilis var. niger

PubMed Central

Angelotti, Robert; Maryanski, James H.; Butler, Thomas F.; Peeler, James T.; Campbell, Jeptha E.

1968-01-01

The dry-heat resistance of Bacillus subtilis var. niger spores located in or on various materials was determined as D and z values in the range of 105 through 160 C. The systems tested included spores located on steel and paper strips, spores located between stainless-steel washers mated together under 150 inch-lb and 12 inch-lb of torque, and spores encapsulated in methylmethacrylate and epoxy plastics. D values for a given temperature varied with the test system. High D values were observed for the systems in which spores were encapsulated or under heavy torque, whereas lower D values were observed for the steel and paper strip systems and the lightly torqued system. Similar z values were obtained for the plastic and steel strip systems (zD = 21 C), but an unusually low z for spores on paper (zD = 12.9 C) and an unusually high z for spores on steel washers mated at 150 inch-lb of torque (zD = 32 C) were observed. The effect of spore moisture content on the D value of spores encapsulated in water-impermeable plastic was determined, and maximal resistance was observed for spores with a water activity (aw) of 0.2 to 0.4. Significantly decreased D values were observed for spores with moisture contents below aw 0.2 or above aw 0.4. The data indicate that the important factors to be considered when measuring the dry heat resistance of spores are (i) the initial moisture content of the spore, (ii) the rate of spore desiccation during heating, (iii) the water retention capacity of the material in or on which spores are located, and (iv) the relative humidity of the system at the test temperature. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 7 PMID:4968962

Effect of sporulation medium on wet-heat resistance and structure of Alicyclobacillus acidoterrestris DSM 3922-type strain spores and modeling of the inactivation kinetics in apple juice.

PubMed

Molva, Celenk; Baysal, Ayse Handan

2014-10-17

Alicyclobacillus acidoterrestris is a spoilage bacterium in fruit juices leading to high economic losses. The present study evaluated the effect of sporulation medium on the thermal inactivation kinetics of A. acidoterrestris DSM 3922 spores in apple juice (pH3.82±0.01; 11.3±0.1 °Brix). Bacillus acidocaldarius agar (BAA), Bacillus acidoterrestris agar (BATA), malt extract agar (MEA), potato dextrose agar (PDA) and B. acidoterrestris broth (BATB) were used for sporulation. Inactivation kinetic parameters at 85, 87.5 and 90°C were obtained using the log-linear model. The decimal reduction times at 85°C (D85°C) were 41.7, 57.6, 76.8, 76.8 and 67.2min; D87.5°C-values were 22.4, 26.7, 32.9, 31.5, and 32.9min; and D90°C-values were 11.6, 9.9, 14.7, 11.9 and 14.1min for spores produced on PDA, MEA, BATA, BAA and BATB, respectively. The estimated z-values were 9.05, 6.60, 6.96, 6.15, and 7.46, respectively. The present study suggests that the sporulation medium affects the wet-heat resistance of A. acidoterrestris DSM 3922 spores. Also, the dipicolinic acid content (DPA) was found highest in heat resistant spores formed on mineral containing media. After wet-heat treatment, loss of internal volume due to the release of DPA from spore core was observed by scanning electron microscopy. Since, there is no standardized media for the sporulation of A. acidoterrestris, the results obtained from this study might be useful to determine and compare the thermal resistance characteristics of A. acidoterrestris spores in fruit juices. Copyright © 2014 Elsevier B.V. All rights reserved.

Debye temperature of metallic nanowires--an experimental determination from the resistance of metallic nanowires in the temperature range 4.2 K-300 K.

PubMed

Bid, Aveek; Bora, Achyut; Raychaudhuri, A K

2007-06-01

We have studied the resistance of metallic nanowires (silver and copper) as a function of the wire diameter in the temperature range 4.2 K-300 K. The nanowires with an average diameter of 15 nm-200 nm and length 6 microm were electrochemically deposited using polycarbonate membranes as template from AgNO3 and CuSO4, respectively. The wires after growth were removed from the membranes by dissolving the polymer in dichloromethane and their crystalline nature confirmed by XRD and TEM studies. The TEM study establishes that the nanowires are single crystalline and can have twin in them. The resistivity data was fitted to Bloch-Gruneisen theorem with the values of Debye temperature and the electron-acoustic phonon coupling constant as the two fit variables. The value of the Debye temperature obtained for the Ag wires was seen to match well with that of the bulk while for Cu wires a significant reduction was observed. The observed increase in resistivity with a decrease in the wire diameter could be explained as due to diffuse surface scattering of the conduction electrons.

Gravimetric water distribution assessment from geoelectrical methods (ERT and EMI) in municipal solid waste landfill.

PubMed

Dumont, Gaël; Pilawski, Tamara; Dzaomuho-Lenieregue, Phidias; Hiligsmann, Serge; Delvigne, Frank; Thonart, Philippe; Robert, Tanguy; Nguyen, Frédéric; Hermans, Thomas

2016-09-01

The gravimetric water content of the waste material is a key parameter in waste biodegradation. Previous studies suggest a correlation between changes in water content and modification of electrical resistivity. This study, based on field work in Mont-Saint-Guibert landfill (Belgium), aimed, on one hand, at characterizing the relationship between gravimetric water content and electrical resistivity and on the other hand, at assessing geoelectrical methods as tools to characterize the gravimetric water distribution in a landfill. Using excavated waste samples obtained after drilling, we investigated the influences of the temperature, the liquid phase conductivity, the compaction and the water content on the electrical resistivity. Our results demonstrate that Archie's law and Campbell's law accurately describe these relationships in municipal solid waste (MSW). Next, we conducted a geophysical survey in situ using two techniques: borehole electromagnetics (EM) and electrical resistivity tomography (ERT). First, in order to validate the use of EM, EM values obtained in situ were compared to electrical resistivity of excavated waste samples from corresponding depths. The petrophysical laws were used to account for the change of environmental parameters (temperature and compaction). A rather good correlation was obtained between direct measurement on waste samples and borehole electromagnetic data. Second, ERT and EM were used to acquire a spatial distribution of the electrical resistivity. Then, using the petrophysical laws, this information was used to estimate the water content distribution. In summary, our results demonstrate that geoelectrical methods represent a pertinent approach to characterize spatial distribution of water content in municipal landfills when properly interpreted using ground truth data. These methods might therefore prove to be valuable tools in waste biodegradation optimization projects. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structure dependent resistivity and dielectric characteristics of tantalum oxynitride thin films produced by magnetron sputtering

NASA Astrophysics Data System (ADS)

Cristea, D.; Crisan, A.; Cretu, N.; Borges, J.; Lopes, C.; Cunha, L.; Ion, V.; Dinescu, M.; Barradas, N. P.; Alves, E.; Apreutesei, M.; Munteanu, D.

2015-11-01

The main purpose of this work is to present and to interpret the change of electrical properties of TaxNyOz thin films, produced by DC reactive magnetron sputtering. Some parameters were varied during deposition: the flow of the reactive gases mixture (N2 and O2, with a constant concentration ratio of 17:3); the substrate voltage bias (grounded, -50 V or -100 V) and the substrate (glass, (1 0 0) Si or high speed steel). The obtained films exhibit significant differences. The variation of the deposition parameters induces variations of the composition, microstructure and morphology. These differences cause variation of the electrical resistivity essentially correlated with the composition and structural changes. The gradual decrease of the Ta concentration in the films induces amorphization and causes a raise of the resistivity. The dielectric characteristics of some of the high resistance TaxNyOz films were obtained in the samples with a capacitor-like design (deposited onto high speed steel, with gold pads deposited on the dielectric TaxNyOz films). Some of these films exhibited dielectric constant values higher than those reported for other tantalum based dielectric films.

Computational methods for structural load and resistance modeling

NASA Technical Reports Server (NTRS)

Thacker, B. H.; Millwater, H. R.; Harren, S. V.

1991-01-01

An automated capability for computing structural reliability considering uncertainties in both load and resistance variables is presented. The computations are carried out using an automated Advanced Mean Value iteration algorithm (AMV +) with performance functions involving load and resistance variables obtained by both explicit and implicit methods. A complete description of the procedures used is given as well as several illustrative examples, verified by Monte Carlo Analysis. In particular, the computational methods described in the paper are shown to be quite accurate and efficient for a material nonlinear structure considering material damage as a function of several primitive random variables. The results show clearly the effectiveness of the algorithms for computing the reliability of large-scale structural systems with a maximum number of resolutions.

Gait of dairy cows on floors with different slipperiness.

PubMed

Telezhenko, E; Magnusson, M; Bergsten, C

2017-08-01

This study assessed the slip resistance of different types of solid flooring in cattle housing using a range of technical tests and gait analysis. Dynamic and static coefficient of friction, skid resistance, and abrasiveness were tested on concrete flooring with a smooth finish, a grooved pattern, or a tamped pattern, acid-resistant mastic asphalt, soft rubber mats, and a worn slatted concrete floor. Coefficients of friction and skid resistance were tested under clean and slurry-soiled conditions. Linear kinematic variables were assessed in 40 cows with trackway measurements after the cows passed over the floors in a straight walk. All gait variables were assessed as deviations from those obtained on the slatted concrete floor, which was used as a baseline. The coefficient of friction tests divided the floors into 3 categories: concrete flooring, which had a low coefficient of friction (0.29-0.41); mastic asphalt flooring, which had medium values (0.38-0.45); and rubber mats, which had high values (0.49-0.57). The highest abrasion (g/10 m) was on the asphalt flooring (4.48), and the concrete flooring with a tamped pattern had significantly higher abrasiveness (2.77) than the other concrete floors (1.26-1.60). Lowest values on the skid-resistance tests (dry/wet) were for smooth concrete (79/35) and mastic asphalt (65/47), especially with a slurry layer on the surface. Gait analysis mainly differentiated floors with higher friction and abrasion by longer strides and better tracking. Step asymmetry was lower on floors with high skid-resistance values. The most secure cow gait, in almost every aspect, was observed on soft rubber mats. Relationships between gait variables and physical floor characteristics ranged from average to weak (partial correlations 0.54-0.16). Thus, none of the physical characteristics alone was informative enough to characterize slip resistance. With reference to gait analysis, the abrasiveness of the hard surfaces was more informative than the coefficient of friction, but the effect of pattern was better detected by skid-resistance measurements. Consequently, several physical characteristics are needed to objectively describe the slip resistance of cattle floors. Soft rubber mats gave better tracking than hard, solid floors, even with a grooved surface or a tamped pattern. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

CFD investigation of pentamaran ship model with chine hull form on the resistance characteristics

NASA Astrophysics Data System (ADS)

Yanuar; Sulistyawati, W.

2018-03-01

This paper presents an investigation of pentamaran hull form with chine hull form to the effects of outriggers position, asymmetry, and deadrise angles on the resistance characteristics. The investigation to the resistance characteristics by modelling pentamaran hull form using chine with symmetrical main hull and asymmetric outboard on the variation deadrise angles: 25°, 30°, 35° and Froude number 0,1 to 0,7. On calm water resistance characteristics of six pentamaran models with chine-hull form examined by variation of deadrise angles by using CFD. Comparation with Wigley hull form, the maximum resistance drag reduction of the chine hull form was reduced by 15.81% on deadrise 25°, 13.8% on deadrise 30°, and 20.38% on deadrise 35°. While the smallest value of total resistance coefficient was generated from chine 35° at R/L:1/14 and R/L:1/7. Optimum hull form for minimum resistance has been obtained, so it is interesting to continue with angle of entrance and stem angle of hull for further research.

In Vitro Sensitivity of Cutaneous Leishmania Promastigote Isolates Circulating in French Guiana to a Set of Drugs

PubMed Central

Ginouvès, Marine; Simon, Stéphane; Nacher, Mathieu; Demar, Magalie; Carme, Bernard; Couppié, Pierre; Prévot, Ghislaine

2017-01-01

Anti-leishmaniasis drug resistance is a common problem worldwide. The aim of this study was to inventory the general in vitro level of sensitivity of Leishmania isolates circulating in French Guiana and to highlight potential in vitro pentamidine-resistant isolates. This sensitivity study was conducted on 36 patient-promastigote isolates for seven drugs (amphotericin B, azithromycin, fluconazole, meglumine antimoniate, miltefosine, paromomycin, and pentamidine) using the Cell Counting Kit-8 viability test. The IC50 values obtained were heterogeneous. One isolate exhibited high IC50 values for almost all drugs tested. Pentamidine, which is the first-line treatment in French Guiana, showed efficacy at very low doses (mean of 0.0038 μg/mL). The concordance of the in vitro pentamidine results with the patients' clinical outcomes was 94% (K = 0.82). PMID:28167598

Structural, optical, morphological and electrical properties of undoped and Al-doped ZnO thin films prepared using sol—gel dip coating process

NASA Astrophysics Data System (ADS)

Boukhenoufa, N.; Mahamdi, R.; Rechem, D.

2016-11-01

In this work, sol—gel dip-coating technique was used to elaborate ZnO pure and ZnO/Al films. The impact of Al-doped concentration on the structural, optical, surface morphological and electrical properties of the elaborated samples was investigated. It was found that better electrical and optical performances have been obtained for an Al concentration equal to 5%, where the ZnO thin films exhibit a resistivity value equal to 1.64104 Ω·cm. Moreover, highest transparency has been recorded for the same Al concentration value. The obtained results from this investigation make the developed thin film structure a potential candidate for high optoelectronic performance applications.

Correlation of Resistivity Value with Geotechnical N-Value of Sedimentary Area in Nusajaya, Johor, Malaysia

NASA Astrophysics Data System (ADS)

Akip Tan, S. N. Mohd; Edy Tonnizam, M.; Saad, R.; Dan, M. F. Md; Nordiana, M. M.; Hazreek, Z. A. M.; Madun, A.

2018-04-01

Electrical resistivity survey and the geotechnical SPT blow counts (N-value) were carried out simultaneously on the tropically weathered sedimentary rock mass for an excavation project at Nusajaya, Johor, Malaysia. This study aims to determine subsurface profile by using 2D-resistivity methods and correlate with N-value derived from boring works. Four boreholes were investigated in five survey lines that revealed the site is underlain by moderately to completely weathered sandstone, clay, silt and shale. Data analysis from 2D-resistivity image shows that zones with high resistivity value generally have high N-value, and vice versa. Five zones have inversed the proportional relation between N-value and resistivity Ωm value due to different types of soil lithology. It indicates that 2D-resistivity is significance to detect bodies of anomalous materials or estimating the depth of bedrock. As a conclusion, the integration of geophysical and geotechnical analysis provides a promise approach to understand some relationship concerning the subsurface subsurface ground through the combination of 2D-resistivity and N-value.

Identification of different geologic units using fuzzy constrained resistivity tomography

NASA Astrophysics Data System (ADS)

Singh, Anand; Sharma, S. P.

2018-01-01

Different geophysical inversion strategies are utilized as a component of an interpretation process that tries to separate geologic units based on the resistivity distribution. In the present study, we present the results of separating different geologic units using fuzzy constrained resistivity tomography. This was accomplished using fuzzy c means, a clustering procedure to improve the 2D resistivity image and geologic separation within the iterative minimization through inversion. First, we developed a Matlab-based inversion technique to obtain a reliable resistivity image using different geophysical data sets (electrical resistivity and electromagnetic data). Following this, the recovered resistivity model was converted into a fuzzy constrained resistivity model by assigning the highest probability value of each model cell to the cluster utilizing fuzzy c means clustering procedure during the iterative process. The efficacy of the algorithm is demonstrated using three synthetic plane wave electromagnetic data sets and one electrical resistivity field dataset. The presented approach shows improvement on the conventional inversion approach to differentiate between different geologic units if the correct number of geologic units will be identified. Further, fuzzy constrained resistivity tomography was performed to examine the augmentation of uranium mineralization in the Beldih open cast mine as a case study. We also compared geologic units identified by fuzzy constrained resistivity tomography with geologic units interpreted from the borehole information.

Antimicrobial susceptibility pattern of Brachyspira intermedia isolates from European layers.

PubMed

Verlinden, Marc; Boyen, Filip; Pasmans, Frank; Garmyn, An; Haesebrouck, Freddy; Martel, An

2011-09-01

A broth microdilution method was used to determine the antimicrobial susceptibility of 20 Brachyspira intermedia isolates obtained from different layer flocks in Belgium and The Netherlands between 2008 and 2010. The antimicrobial agents used were tylosin, tilmicosin, tiamulin, valnemulin, doxycycline, and lincomycin. The minimal inhibitory concentration (MIC) distribution patterns of tylosin, tilmicosin, lincomycin, and doxycycline were bimodal, demonstrating acquired resistance against doxycycline in three strains, against the macrolides in two strains, and against lincomycin in one strain. The MICs of tiamulin and valnemulin showed a monomodal distribution, but with tailing toward the higher MIC values, possibly suggesting low-level acquired resistance in six isolates. Sequencing revealed a G1058C mutation in the 16S rRNA gene in all doxycycline-resistant strains. The strain resistant to tylosin, tilmicosin, and lincomycin had an A2058T mutation in the 23S rRNA gene.

Detection of tuberculosis drug resistance: a comparison by Mycobacterium tuberculosis MLPA assay versus Genotype®MTBDRplus.

PubMed

Santos, Paula Fernanda Gonçalves Dos; Costa, Elis Regina Dalla; Ramalho, Daniela M; Rossetti, Maria Lucia; Barcellos, Regina Bones; Nunes, Luciana de Souza; Esteves, Leonardo Souza; Rodenbusch, Rodrigo; Anthony, Richard M; Bergval, Indra; Sengstake, Sarah; Viveiros, Miguel; Kritski, Afrânio; Oliveira, Martha M

2017-06-01

To cope with the emergence of multidrug-resistant tuberculosis (MDR-TB), new molecular methods that can routinely be used to screen for a wide range of drug resistance related genetic markers in the Mycobacterium tuberculosis genome are urgently needed. To evaluate the performance of multiplex ligaton-dependent probe amplification (MLPA) against Genotype® MTBDRplus to detect resistance to isoniazid (INHr) and rifampicin (RIFr). 96 culture isolates characterised for identification, drug susceptibility testing (DST) and sequencing of rpoB, katG, and inhA genes were evaluated by the MLPA and Genotype®MTBDRplus assays. With sequencing as a reference standard, sensitivity (SE) to detect INHr was 92.8% and 85.7%, and specificity (SP) was 100% and 97.5%, for MLPA and Genotype®MTBDRplus, respectively. In relation to RIFr, SE was 87.5% and 100%, and SP was 100% and 98.8%, respectively. Kappa value was identical between Genotype®MTBDRplus and MLPA compared with the standard DST and sequencing for detection of INHr [0.83 (0.75-0.91)] and RIFr [0.93 (0.88-0.98)]. Compared to Genotype®MTBDRplus, MLPA showed similar sensitivity to detect INH and RIF resistance. The results obtained by the MLPA and Genotype®MTBDRplus assays indicate that both molecular tests can be used for the rapid detection of drug-resistant TB with high accuracy. MLPA has the added value of providing information on the circulating M. tuberculosis lineages.

Corrosion Sensor for Monitoring the Service Condition of Chloride-Contaminated Cement Mortar

PubMed Central

Lu, Shuang; Ba, Heng-Jing

2010-01-01

A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (Rp) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (Rs). The results show that the polarization resistance is related to the chloride content and Rs; ln (Rp) is linearly related to the Rs values in mortar without added chloride. The relationships observed between the Rp of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that Rs can indicate the corrosion state of concrete structures. PMID:22319347

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

Torlakoglu, A.; Gueclue, G.

Waste polyethylene terephthalate (PET) flakes were depolymerized by using propylene glycol (PG) in the presence of zinc acetate as catalyst. Glycolysis reaction products of waste PET obtained by using PET/glycol molar ratio 1/2. Two short oil alkyd resins of high acid values (30-40 mgKOH/g) were prepared from phthalic anhydride (PA), glycerin (G), coconut oil fatty acids (COFA) and glycolyzed products of waste PET (PET-based alkyd resins) or glycols (PG) (reference alkyd resins). These alkyd resins were blended with 30%, 40%, and 50% of a commercial urea-formaldehyde, melamine-formaldehyde and urea-formaldehyde/melamine-formaldehyde mixture (1/1 weight ratio) and heated at 140 deg. C. Themore » physical and chemical properties such as drying time, hardness, abrasion resistance, adhesion strength, water resistance, alkaline resistance, acid resistance, gelation time, and thermal oxidative degradation resistance (with thermogravimetric analysis, TGA) of these alkyd-amino resins were investigated. The properties of the waste PET-based resins were found to be compatible with the properties of the reference resins.« less

A one-layer satellite surface energy balance for estimating evapotranspiration rates and crop water stress indexes.

PubMed

Barbagallo, Salvatore; Consoli, Simona; Russo, Alfonso

2009-01-01

Daily evapotranspiration fluxes over the semi-arid Catania Plain area (Eastern Sicily, Italy) were evaluated using remotely sensed data from Landsat Thematic Mapper TM5 images. A one-source parameterization of the surface sensible heat flux exchange using satellite surface temperature has been used. The transfer of sensible and latent heat is described by aerodynamic resistance and surface resistance. Required model inputs are brightness, temperature, fractional vegetation cover or leaf area index, albedo, crop height, roughness lengths, net radiation, air temperature, air humidity and wind speed. The aerodynamic resistance (r(ah)) is formulated on the basis of the Monin-Obukhov surface layer similarity theory and the surface resistance (r(s)) is evaluated from the energy balance equation. The instantaneous surface flux values were converted into evaporative fraction (EF) over the heterogeneous land surface to derive daily evapotranspiration values. Remote sensing-based assessments of crop water stress (CWSI) were also made in order to identify local irrigation requirements. Evapotranspiration data and crop coefficient values obtained from the approach were compared with: (i) data from the semi-empirical approach "K(c) reflectance-based", which integrates satellite data in the visible and NIR regions of the electromagnetic spectrum with ground-based measurements and (ii) surface energy flux measurements collected from a micrometeorological tower located in the experiment area. The expected variability associated with ET flux measurements suggests that the approach-derived surface fluxes were in acceptable agreement with the observations.

Effect of the medium characteristics and the heating and cooling rates on the nonisothermal heat resistance of Bacillus sporothermodurans IC4 spores.

PubMed

Esteban, María-Dolores; Huertas, Juan-Pablo; Fernández, Pablo S; Palop, Alfredo

2013-05-01

In recent years, highly thermo-resistant mesophilic spore-forming bacteria belonging to the species Bacillus sporothermodurans have caused non-sterility problems in industrial sterilization processes. The aim of this research was to evaluate the effect of the heating medium characteristics (pH and buffer/food) on the thermal inactivation of B. sporothermodurans spores when exposed to isothermal and non-isothermal heating and cooling treatments and the suitability of non-linear Weibull and Geeraaerd models to predict the survivors of these thermal treatments. Thermal treatments were carried out in pH 3, 5 and 7 McIlvaine buffer and in a courgette soup. Isothermal survival curves showed shoulders that were accurately characterized by means of both models. A clear effect of the pH of the heating medium was observed, decreasing the D120 value from pH 7 to pH 3 buffer down to one third. Differences in heat resistance were similar, regardless of the model used and were kept at all temperatures tested. The heat resistance in courgette soup was similar to that shown in pH 7 buffer. When the heat resistance values obtained under isothermal conditions were used to predict the survival in the non-isothermical experiments, the predictions estimated the experimental data quite accurately, both with Weibull and Geeraerd models. Copyright © 2012 Elsevier Ltd. All rights reserved.

Design of a soil cutting resistance sensor for application in site-specific tillage.

PubMed

Agüera, Juan; Carballido, Jacob; Gil, Jesús; Gliever, Chris J; Perez-Ruiz, Manuel

2013-05-10

One objective of precision agriculture is to provide accurate information about soil and crop properties to optimize the management of agricultural inputs to meet site-specific needs. This paper describes the development of a sensor equipped with RTK-GPS technology that continuously and efficiently measures soil cutting resistance at various depths while traversing the field. Laboratory and preliminary field tests verified the accuracy of this prototype soil strength sensor. The data obtained using a hand-operated soil cone penetrometer was used to evaluate this field soil compaction depth profile sensor. To date, this sensor has only been tested in one field under one gravimetric water content condition. This field test revealed that the relationships between the soil strength profile sensor (SSPS) cutting force and soil cone index values are assumed to be quadratic for the various depths considered: 0-10, 10-20 and 20-30 cm (r2 = 0.58, 0.45 and 0.54, respectively). Soil resistance contour maps illustrated its practical value. The developed sensor provides accurate, timely and affordable information on soil properties to optimize resources and improve agricultural economy.

A new warfarin dosing algorithm including VKORC1 3730 G > A polymorphism: comparison with results obtained by other published algorithms.

PubMed

Cini, Michela; Legnani, Cristina; Cosmi, Benilde; Guazzaloca, Giuliana; Valdrè, Lelia; Frascaro, Mirella; Palareti, Gualtiero

2012-08-01

Warfarin dosing is affected by clinical and genetic variants, but the contribution of the genotype associated with warfarin resistance in pharmacogenetic algorithms has not been well assessed yet. We developed a new dosing algorithm including polymorphisms associated both with warfarin sensitivity and resistance in the Italian population, and its performance was compared with those of eight previously published algorithms. Clinical and genetic data (CYP2C9*2, CYP2C9*3, VKORC1 -1639 G > A, and VKORC1 3730 G > A) were used to elaborate the new algorithm. Derivation and validation groups comprised 55 (58.2% men, mean age 69 years) and 40 (57.5% men, mean age 70 years) patients, respectively, who were on stable anticoagulation therapy for at least 3 months with different oral anticoagulation therapy (OAT) indications. Performance of the new algorithm, evaluated with mean absolute error (MAE) defined as the absolute value of the difference between observed daily maintenance dose and predicted daily dose, correlation with the observed dose and R(2) value, was comparable with or slightly lower than that obtained using the other algorithms. The new algorithm could correctly assign 53.3%, 50.0%, and 57.1% of patients to the low (≤25 mg/week), intermediate (26-44 mg/week) and high (≥ 45 mg/week) dosing range, respectively. Our data showed a significant increase in predictive accuracy among patients requiring high warfarin dose compared with the other algorithms (ranging from 0% to 28.6%). The algorithm including VKORC1 3730 G > A, associated with warfarin resistance, allowed a more accurate identification of resistant patients who require higher warfarin dosage.

Robustness and Radiation Resistance of the Pale Grass Blue Butterfly from Radioactively Contaminated Areas: A Possible Case of Adaptive Evolution.

PubMed

Nohara, Chiyo; Hiyama, Atsuki; Taira, Wataru; Otaki, Joji M

2018-02-14

The pale grass blue butterfly, Zizeeria maha, has been used to evaluate biological impacts of the Fukushima nuclear accident in March 2011. Here, we examined the possibility that butterflies have adapted to be robust in the contaminated environment. Larvae (n = 2432) were obtained from adult butterflies (n = 20) collected from 7 localities with various contamination levels in May 2012, corresponding to the 7th generation after the accident. When the larvae were reared on non-contaminated host plant leaves from Okinawa, the normality rates of natural exposure without artificial irradiation (as an indication of robustness) were high not only in the least contaminated locality but also in the most contaminated localities. The normality rates were similarly obtained when the larvae were reared on non-contaminated leaves with external irradiation or on contaminated leaves from Fukushima to deliver internal irradiation. The normality rate of natural exposure and that of external or internal exposure were correlated, suggesting that radiation resistance (or susceptibility) likely reflects general state of health. The normality rate of external or internal exposure was divided by the relative normality rate of natural exposure, being defined as the resistance value. The resistance value was the highest in the populations of heavily contaminated localities and was inversely correlated with the distance from the Fukushima Dai-ichi nuclear power plant. These results suggest that the butterfly population might have adapted to the contaminated environment within approximately 1 year after the accident. The present study may partly explain the decrease in mortality and abnormality rates later observed in the contaminated areas. © The American Genetic Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Electric structure of the Copahue Volcano (Neuquén Province, Argentina), from magnetotelluric soundings: 1D and 2D modellings

NASA Astrophysics Data System (ADS)

Mamaní, M. J.; Borzotta, E.; Venencia, J. E.; Maidana, A.; Moyano, C. E.; Castiglione, B.

2000-05-01

Four magnetotelluric soundings were carried out in 1993 in the region of the Copahue active volcano located at the border between Chile and Argentina (37°45'S, 71°18'W). Three soundings were located inside the caldera of the ancient stratovolcano (east of Copahue) and the fourth outside it. The soundings inside the caldera were situated at about 6, 11, and 14 km from the volcano. Digital data were obtained covering the range of periods from 1 sec to 10,000 sec using induction coils and a flux-gate magnetometer to obtain the magnetic data and Cu-SO 4Cu electrodes for electric field measurements. The apparent resistivity curves corresponding to principal directions were analyzed in conjunction with the geological background in order to eliminate distortion — which is very important in this hot volcanic region. Then, 1D modellings were performed using the "normal" curves — i.e., curves without distortions. Using the apparent resistivity curves with distortions, 2D modelling was also performed along a profile perpendicular to the regional tectonic trend suggested by MT soundings into the caldera. Results show low resistivity values of about 3-15 Ωm between 9 km to 20 km depth in the crust, suggesting high temperatures, with minimum values of about 700°C with partially melted zones in the upper crust between 9 km to 20 km depth under the caldera. The presence of a possible sulphide-carbonaceous layer (SC layer) in the upper basement could play an important role in lowering the electrical resistivities because of its high electronic conductivity.

Discerning Apical and Basolateral Properties of HT-29/B6 and IPEC-J2 Cell Layers by Impedance Spectroscopy, Mathematical Modeling and Machine Learning

PubMed Central

Schmid, Thomas; Bogdan, Martin; Günzel, Dorothee

2013-01-01

Quantifying changes in partial resistances of epithelial barriers in vitro is a challenging and time-consuming task in physiology and pathophysiology. Here, we demonstrate that electrical properties of epithelial barriers can be estimated reliably by combining impedance spectroscopy measurements, mathematical modeling and machine learning algorithms. Conventional impedance spectroscopy is often used to estimate epithelial capacitance as well as epithelial and subepithelial resistance. Based on this, the more refined two-path impedance spectroscopy makes it possible to further distinguish transcellular and paracellular resistances. In a next step, transcellular properties may be further divided into their apical and basolateral components. The accuracy of these derived values, however, strongly depends on the accuracy of the initial estimates. To obtain adequate accuracy in estimating subepithelial and epithelial resistance, artificial neural networks were trained to estimate these parameters from model impedance spectra. Spectra that reflect behavior of either HT-29/B6 or IPEC-J2 cells as well as the data scatter intrinsic to the used experimental setup were created computationally. To prove the proposed approach, reliability of the estimations was assessed with both modeled and measured impedance spectra. Transcellular and paracellular resistances obtained by such neural network-enhanced two-path impedance spectroscopy are shown to be sufficiently reliable to derive the underlying apical and basolateral resistances and capacitances. As an exemplary perturbation of pathophysiological importance, the effect of forskolin on the apical resistance of HT-29/B6 cells was quantified. PMID:23840862

Resistivity behavior of hydrogen and liquid silane at high shock compression

NASA Astrophysics Data System (ADS)

Wang, Yi-Gao; Liu, Fu-Sheng; Liu, Qi-Jun

2018-07-01

To study the electrical properties of hydrogen rich compounds under extreme conditions, the electrical resistivity of density hydrogen and silane fluid was measured, respectively. The hydrogen sample was prepared by compressing pure hydrogen gas to 10 MPa in a coolant target system at the temperature of 77 K. The silane sample can be obtained with the same method. High-pressure and high-temperature experiments were performed using a two-stage light-gas gun. The electrical resistivity of the sample decreased with increasing pressure and temperature as expected. A minimum electrical resistivity value of 0.3 × 10-3 Ω cm at 138 GPa and 4100 K was obtained for silane. The minimum resistivity of hydrogen in the state of 102 GPa and 4300 K was 0.35 Ω cm. It showed that the measured electrical resistivity of the shock-compressed hydrogen was an order of magnitude higher than fluid silane at 50-90 GPa. However, beyond 100 GPa, the resistivity difference between silane and hydrogen was very minor. The carriers in the sample were hydrogen, and the concentration of hydrogen atoms in these two substances was close to each other. These results supported the theoretical prediction that silane was interpreted simply in terms of chemical decomposition into silicon nanoparticles and fluid hydrogen, and electrical conduction flows predominately dominated by the fluid hydrogen. In addition, the results also supported the theory of "chemical precompression", the existence of Sisbnd H bond helped to reduce the pressure of hydrogen metallization. These findings could lead the way for further metallic phases of hydrogen-rich materials and experimental studies.

Transfontanellar duplex brain ultrasonography resistive indices as a prognostic tool in neonatal hypoxic-ischemic encephalopathy before and after treatment with therapeutic hypothermia.

PubMed

Gerner, G J; Burton, V J; Poretti, A; Bosemani, T; Cristofalo, E; Tekes, A; Seyfert, D; Parkinson, C; Leppert, M; Allen, M; Huisman, T A G M; Northington, F J; Johnston, M V

2016-03-01

Prior to therapeutic hypothermia (that is, cooling), transfontanellar duplex brain sonography resistive indices (RI) were studied as a bedside non-invasive measures of cerebral hemodynamics in neonates who suffered from hypoxic-ischemic encephalopathy (HIE). We compared pre- and post-cooling RI values and examined the relationships between RI values and specific long-term neurodevelopmental outcomes. Transfontanellar duplex brain sonography, including RI, were obtained for 28 neonates prior to cooling and for 20 neonates following cooling. All RI values were sampled in the anterior cerebral artery at the beginning of each ultrasound study. Neurodevelopmental assessment was conducted between ages 20-32 months with the Mullen Scale of Early Learning. The relationships between pre- and post-cooling RI and cognitive and motor outcomes were studied. Neonates with RI values <0.60 prior to and following cooling were more likely to die or have severe neurodevelopmental disability by ages 20-32 months than those with RI>0.60. Lower RI values were associated with specific neurodevelopmental deficits in motor skill attainment. Pre- and post-cooling transfontanellar duplex brain sonography RI values may be a useful prognostic tool, in conjunction with other clinical information, for neonates diagnosed with HIE. The results of this study suggest that further study of the prognostic value of RI values for short- and long-term outcomes is warranted.

Shunt resistance and saturation current determination in CdTe and CIGS solar cells. Part 1: a new theoretical procedure and comparison with other methodologies

NASA Astrophysics Data System (ADS)

Rangel-Kuoppa, Victor-Tapio; Albor-Aguilera, María-de-Lourdes; Hérnandez-Vásquez, César; Flores-Márquez, José-Manuel; González-Trujillo, Miguel-Ángel; Contreras-Puente, Gerardo-Silverio

2018-04-01

A new proposal for the extraction of the shunt resistance (R sh ) and saturation current (I sat ) of a current-voltage (I-V) measurement of a solar cell, within the one-diode model, is given. First, the Cheung method is extended to obtain the series resistance (R s ), the ideality factor (n) and an upper limit for I sat . In this article which is Part 1 of two parts, two procedures are proposed to obtain fitting values for R sh and I sat within some voltage range. These two procedures are used in two simulated I-V curves (one in darkness and the other one under illumination) to recover the known solar cell parameters R sh , R s , n, I sat and the light current I lig and test its accuracy. The method is compared with two different common parameter extraction methods. These three procedures are used and compared in Part 2 in the I-V curves of CdS-CdTe and CIGS-CdS solar cells.

Efficiency of circulant diallels via mixed models in the selection of papaya genotypes resistant to foliar fungal diseases.

PubMed

Vivas, M; Silveira, S F; Viana, A P; Amaral, A T; Cardoso, D L; Pereira, M G

2014-07-02

Diallel crossing methods provide information regarding the performance of genitors between themselves and their hybrid combinations. However, with a large number of parents, the number of hybrid combinations that can be obtained and evaluated become limited. One option regarding the number of parents involved is the adoption of circulant diallels. However, information is lacking regarding diallel analysis using mixed models. This study aimed to evaluate the efficacy of the method of linear mixed models to estimate, for variable resistance to foliar fungal diseases, components of general and specific combining ability in a circulant table with different s values. Subsequently, 50 diallels were simulated for each s value, and the correlations and estimates of the combining abilities of the different diallel combinations were analyzed. The circulant diallel method using mixed modeling was effective in the classification of genitors regarding their combining abilities relative to the complete diallels. The numbers of crosses in which each genitor(s) will compose the circulant diallel and the estimated heritability affect the combining ability estimates. With three crosses per parent, it is possible to obtain good concordance (correlation above 0.8) between the combining ability estimates.

Synthesis and electrical properties of BaBiO 3 and high resistivity BaTiO 3 –BaBiO 3 ceramics

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

Kumar, Nitish; Golledge, Stephen L.; Cann, David P.

2016-12-01

Ceramics of the composition BaBiO3 (BB) were sintered in oxygen to obtain a single phase with monoclinic II2/mm symmetry as suggested by high-resolution X-ray diffraction. X-ray photoelectron spectroscopy confirmed the presence of bismuth in two valence states - 3+ and 5+. Optical spectroscopy showed presence of a direct bandgap at ~ 2.2eV and a possible indirect bandgap at ~ 0.9eV. This combined with determination of the activation energy for conduction of 0.25eV, as obtained from ac impedance spectroscopy, suggested that a polaron-mediated conduction mechanism was prevalent in BB. The BB ceramics were crushed, mixed with BaTiO3 (BT), and sintered tomore » obtain BT–BB solid solutions. All the ceramics had tetragonal symmetry and exhibited a normal ferroelectric-like dielectric response. Using ac impedance and optical spectroscopy, it was shown that resistivity values of BT–BB were orders of magnitude higher than BT or BB alone, indicating a change in the fundamental defect equilibrium conditions. A shift in the site occupancy of Bi to the A-site is proposed to be the mechanism for the increased electrical resistivity.« less

Agar dilution and agar screen with cefoxitin and oxacillin: what is known and what is unknown in detection of meticillin-resistant Staphylococcus aureus.

PubMed

Perez, Leandro Reus Rodrigues; Dias, Cícero; d'Azevedo, Pedro Alves

2008-08-01

In this study we evaluated the performance of the oxacillin agar screen test, and agar dilution tests using cefoxitin and oxacillin antimicrobials, to detect meticillin resistance in Staphylococcus aureus isolates. The presence of the mecA gene, detected by PCR, was used as the standard to which agar screen and agar dilution tests were compared. The best performance was obtained using the agar dilution test (99.4 % accuracy) with breakpoints of 4 mug ml(-1) for oxacillin and 8 mug ml(-1) for cefoxitin, and using the oxacillin agar screen test. Also, a strong correlation between MIC values of cefoxitin and oxacillin permits the use of either drug for detection of meticillin resistance.

Multiscale Modeling of Thermal Conductivity of Polymer/Carbon Nanocomposites

NASA Technical Reports Server (NTRS)

Clancy, Thomas C.; Frankland, Sarah-Jane V.; Hinkley, Jeffrey A.; Gates, Thomas S.

2010-01-01

Molecular dynamics simulation was used to estimate the interfacial thermal (Kapitza) resistance between nanoparticles and amorphous and crystalline polymer matrices. Bulk thermal conductivities of the nanocomposites were then estimated using an established effective medium approach. To study functionalization, oligomeric ethylene-vinyl alcohol copolymers were chemically bonded to a single wall carbon nanotube. The results, in a poly(ethylene-vinyl acetate) matrix, are similar to those obtained previously for grafted linear hydrocarbon chains. To study the effect of noncovalent functionalization, two types of polyethylene matrices. -- aligned (extended-chain crystalline) vs. amorphous (random coils) were modeled. Both matrices produced the same interfacial thermal resistance values. Finally, functionalization of edges and faces of plate-like graphite nanoparticles was found to be only modestly effective in reducing the interfacial thermal resistance and improving the composite thermal conductivity

Distribution of macrolide resistance mechanisms in Bulgarian clinical isolates of Streptococcus pyogenes during the years of 2013-2016.

PubMed

Muhtarova, Adile A; Gergova, Raina T; Mitov, Ivan G

2017-09-01

Streptococcus pyogenes, or group A streptococcus (GAS), is the main etiological agent of bacterial tonsillopharyngitis and a common cause of a wide variety of other mild to severe infections. Objectives of the present study was to determine and evaluate the distribution of genetic mechanisms associated with certain phenotypes of macrolide resistance in Bulgarian GAS isolated during the years of 2013-2016. All GAS strains were screened for the macrolide resistance genes erm(A), erm(B) and mef(A), using multiplex polymerase chain reaction (PCR). The minimal inhibitory concentrations (MICs) of erythromycin, azithromycin, clarithromycin, clindamycin were determined by E-tests. Almost 23% of GAS isolates obtained in 2013-2014 and near 40% of them in 2015-2016 contained various elements of resistance. The predominant gene was mef(A), which encodes an efflux pump (M-phenotype), identified in 57.84% of the macrolide-resistant strains. The next frequently prevalent mechanism was a combination of mef(A) and erm(B) in 22.55%, which determined high-level inducible or constitutive resistance to macrolides, lincosamides and streptogramins (iMLSB or cMLSB). The highest MIC value (>256mg/L) was detected in association with erm(B) (p<0.05). The MIC range was observed to be much higher in the isolates with combinations of resistance genes vs. those with mef genes alone (p<0.05). The data about the distribution and prevalence of macrolide resistance mechanisms obtained in this study can help in the treatment of persistent and recurrent GAS infections and in the correct choice of empiric therapy. Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

Multifunctional surface modification of silk fabric via graphene oxide repeatedly coating and chemical reduction method

NASA Astrophysics Data System (ADS)

Cao, Jiliang; Wang, Chaoxia

2017-05-01

Multifunctional silk fabrics with electrical conductive, anti-ultraviolet and water repellent were successfully prepared by surface modification with graphene oxide (GO). The yellow-brown GO deposited on the surface of silk fabric was converted into graphitic black reduced graphene (RGO) by sodium hydrosulfite. The surface properties of silk fabrics were changed by repeatedly RGO coating process, which have been proved by SEM and XPS. The SEM results showed that the RGO sheets were successive form a continuously thin film on the surface of silk fabrics, and the deposition of GO or RGO also can be proved by XPS. The electrical conductivity was tested by electrical surface resistance value of the silk fabric, the surface resistance decreased with increasing of RGO surface modification times, and a low surface resistance value reached to 3.24 KΩ cm-1 after 9 times of modification, indicating the silk obtained excellent conductivity. The UPF value of one time GO modification silk fabric (silk-1RGO) was enhanced significantly to 24.45 in comparison to 10.40 of original silk. The contact angle of RGO coating silk samples was all above of 120°. The durability of RGO coated silk fabrics was tested by laundering. The electrical surface resistance of silk-4RGO (65.74 KΩ cm-1), silk-6RGO (15.54 KΩ cm-1) and silk-8RGO (3.86 KΩ cm-1) fabrics was up to 86.82, 22.30 and 6.57 KΩ cm-1 after 10 times of standard washing, respectively. The UPF value, contact angle and color differences of RGO modified silk fabric slightly changed before and after 10 times of standard washing. Therefore, the washing fastness of electric conduction, anti-ultraviolet and water repellent multifunctional silk fabrics was excellent.

A technique for the determination of center of gravity and rolling resistance for tilt-seat wheelchairs.

PubMed

Lemaire, E D; Lamontagne, M; Barclay, H W; John, T; Martel, G

1991-01-01

A balance platform setup was defined for use in the determination of the center of gravity in the sagittal plane for a wheelchair and patient. Using the center of gravity information, measurements from the wheelchair and patient (weight, tire coefficients of friction), and various assumptions (constant speed, level-concrete surface, patient-wheelchair system is a rigid body), a method for estimating the rolling resistance for a wheelchair was outlined. The center of gravity and rolling resistance techniques were validated against criterion values (center of gravity error = 1 percent, rolling resistance root mean square error = 0.33 N, rolling resistance Pearson correlation coefficient = 0.995). Consistent results were also obtained from a test dummy and five subjects. Once the center of gravity is known, it is possible to evaluate the stability of a wheelchair (in terms of tipping over) and the interaction between the level of stability and rolling resistance. These quantitative measures are expected to be of use in the setup of wheelchairs with a variable seat angle and variable wheelbase length or when making comparisons between different wheelchairs.

Upscaling of spectral induced polarization response using random tube networks

NASA Astrophysics Data System (ADS)

Maineult, Alexis; Revil, André; Camerlynck, Christian; Florsch, Nicolas; Titov, Konstantin

2017-05-01

In order to upscale the induced polarization (IP) response of porous media, from the pore scale to the sample scale, we implement a procedure to compute the macroscopic complex resistivity response of random tube networks. A network is made of a 2-D square-meshed grid of connected tubes, which obey to a given tube radius distribution. In a simplified approach, the electrical impedance of each tube follows a local Pelton resistivity model, with identical resistivity, chargeability and Cole-Cole exponent values for all the tubes-only the time constant varies, as it depends on the radius of each tube and on a diffusion coefficient also identical for all the tubes. By solving the conservation law for the electrical charge, the macroscopic IP response of the network is obtained. We fit successfully the macroscopic complex resistivity also by a Pelton resistivity model. Simulations on uncorrelated and correlated networks, for which the tube radius distribution is so that the decimal logarithm of the radius is normally distributed, evidence that the local and macroscopic model parameters are the same, except the Cole-Cole exponent: its macroscopic value diminishes with increasing heterogeneity (i.e. with increasing standard deviation of the radius distribution), compared to its local value. The methodology is also applied to six siliciclastic rock samples, for which the pore radius distributions from mercury porosimetry are available. These samples exhibit the same behaviour as synthetic media, that is, the macroscopic Cole-Cole exponent is always lower than the local one. As a conclusion, the pore network method seems to be a promising tool for studying the upscaling of the IP response of porous media.

A variation in NOS1AP gene is associated with repaglinide efficacy on insulin resistance in type 2 diabetes of Chinese

PubMed Central

Qin, Wen; Zhang, Rong; Hu, Cheng; Wang, Cong-rong; Lu, Jing-yi; Yu, Wei-hui; Bao, Yu-qian; Xiang, Kun-san; Jia, Wei-ping

2010-01-01

Aim: To investigate a potential association between SNP rs10494366 in the neural nitric oxide synthase adaptor protein (NOS1AP) and efficacy of repaglinide (an insulin secretagogue) in newly diagnosed Shanghai Chinese type 2 diabetes patients. Methods: A total of 104 newly diagnosed type 2 diabetes patients (69 men, 35 women) were recruited and treated with repaglinide for 24 weeks. Anthropometric measurements, clinical laboratory tests were obtained at baseline and after 24-week treatment. Genotyping was performed by sequencing. Results: The baseline value of BMI, HOMA-IR, HOMA-B, and fasting insulin level were significantly different between GG, GT, and TT genotypes (P=0.024, 0.030, 0.005, and 0.007, respectively). Carriers of TT genotype were in significant insulin resistance at baseline. After 24-week repaglinide monotherapy, the Δ value of fasting insulin (P=0.019) and HOMA-IR (P=0.011) were significantly different. TT carriers had the least insulin resistance after treatment. The mixed model analysis showed that the variation had an interaction effect with repaglinide treatment only on HOMA-IR (P=0.013). Conclusion: A common variant in rs10494366 is associated with repaglinide monotherapy efficacy on insulin resistance in newly diagnosed Shanghai Chinese type 2 diabetes patients. PMID:20305679

A variation in NOS1AP gene is associated with repaglinide efficacy on insulin resistance in type 2 diabetes of Chinese.

PubMed

Qin, Wen; Zhang, Rong; Hu, Cheng; Wang, Cong-rong; Lu, Jing-yi; Yu, Wei-hui; Bao, Yu-qian; Xiang, Kun-san; Jia, Wei-ping

2010-04-01

To investigate a potential association between SNP rs10494366 in the neural nitric oxide synthase adaptor protein (NOS1AP) and efficacy of repaglinide (an insulin secretagogue) in newly diagnosed Shanghai Chinese type 2 diabetes patients. A total of 104 newly diagnosed type 2 diabetes patients (69 men, 35 women) were recruited and treated with repaglinide for 24 weeks. Anthropometric measurements, clinical laboratory tests were obtained at baseline and after 24-week treatment. Genotyping was performed by sequencing. The baseline value of BMI, HOMA-IR, HOMA-B, and fasting insulin level were significantly different between GG, GT, and TT genotypes (P=0.024, 0.030, 0.005, and 0.007, respectively). Carriers of TT genotype were in significant insulin resistance at baseline. After 24-week repaglinide monotherapy, the Delta value of fasting insulin (P=0.019) and HOMA-IR (P=0.011) were significantly different. TT carriers had the least insulin resistance after treatment. The mixed model analysis showed that the variation had an interaction effect with repaglinide treatment only on HOMA-IR (P=0.013). A common variant in rs10494366 is associated with repaglinide monotherapy efficacy on insulin resistance in newly diagnosed Shanghai Chinese type 2 diabetes patients.

Theoretical and experimental analysis of the contact between a solid-rubber tire and a chassis dynamometer

NASA Astrophysics Data System (ADS)

Belkin, A. E.; Semenov, V. K.

2016-05-01

We consider the problem of modeling the test where a solid-rubber tire runs on a chassis dynamometer for determining the tire rolling resistance characteristics.We state the problem of free steady-state rolling of the tire along the test drum with the energy scattering in the rubber in the course of cyclic deformation taken into account. The viscoelastic behavior of the rubber is described by the Bergströ m-Boyce model whose numerical parameters are experimentally determined from the results of compression tests with specimens. The finite element method is used to obtain the solution of the three-dimensional viscoelasticity problem. To estimate the adequacy of the constructed model, we compare the numerical results with the results obtained in the solid-rubber tire tests on the Hasbach stand from the values of the rolling resistance forces for various loads on the tire.

Solfatara volcano subsurface imaging: two different approaches to process and interpret multi-variate data sets

NASA Astrophysics Data System (ADS)

Bernardinetti, Stefano; Bruno, Pier Paolo; Lavoué, François; Gresse, Marceau; Vandemeulebrouck, Jean; Revil, André

2017-04-01

The need to reduce model uncertainty and produce a more reliable geophysical imaging and interpretations is nowadays a fundamental task required to geophysics techniques applied in complex environments such as Solfatara Volcano. The use of independent geophysical methods allows to obtain many information on the subsurface due to the different sensitivities of the data towards parameters such as compressional and shearing wave velocities, bulk electrical conductivity, or density. The joint processing of these multiple physical properties can lead to a very detailed characterization of the subsurface and therefore enhance our imaging and our interpretation. In this work, we develop two different processing approaches based on reflection seismology and seismic P-wave tomography on one hand, and electrical data acquired over the same line, on the other hand. From these data, we obtain an image-guided electrical resistivity tomography and a post processing integration of tomographic results. The image-guided electrical resistivity tomography is obtained by regularizing the inversion of the electrical data with structural constraints extracted from a migrated seismic section using image processing tools. This approach enables to focus the reconstruction of electrical resistivity anomalies along the features visible in the seismic section, and acts as a guide for interpretation in terms of subsurface structures and processes. To integrate co-registrated P-wave velocity and electrical resistivity values, we apply a data mining tool, the k-means algorithm, to individuate relationships between the two set of variables. This algorithm permits to individuate different clusters with the objective to minimize the sum of squared Euclidean distances within each cluster and maximize it between clusters for the multivariate data set. We obtain a partitioning of the multivariate data set in a finite number of well-correlated clusters, representative of the optimum clustering of our geophysical variables (P-wave velocities and electrical resistivities). The result is an integrated tomography that shows a finite number of homogeneous geophysical facies, and therefore permits to highlight the main geological features of the subsurface.

Process for obtaining multiple sheet resistances for thin film hybrid microcircuit resistors

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

Norwood, D P

1989-01-31

A standard thin film circuit containing Ta/sub 2/N (100 ohms/square) resistors is fabricated by depositing on a dielectric substrate successive layers of Ta/sub 2/N, Ti and Pd, with a gold layer to provide conductors. The addition of a few simple photoprocessing steps to the standard TFN (thin film network) manufacturing process enables the formation of Ta/sub 2/N + Ti (10 ohms/square) and Ta/sub 2/N + Ti + Pd (1 ohm/square) resistors in the same otherwise standard thin film circuit structure. All three types of resistors are temperature-stable and laser-trimmable for precise definition of resistance values.

Orchard factors associated with resistance and cross resistance to sterol demethylation inhibitor fungicides in populations of Venturia inaequalis from Pennsylvania.

PubMed

Pfeufer, Emily E; Ngugi, Henry K

2012-03-01

Orchard management practices, such as destroying of overwintered inoculum and limiting the number of fungicide applications, are often recommended as tactics for slowing the development of resistance to sterol demethylation-inhibitor (DMI) fungicides in populations of Venturia inaequalis. However, there is little quantitative evidence relating the use of such practices to levels of resistance in orchards. The aim of this study was to evaluate the sensitivity of V. inaequalis isolates from Pennsylvania to DMI fungicides, and to identify orchard management factors related to the incidence of resistant isolates. In total, 644 single-spore V. inaequalis cultures obtained from 20 apple orchards in 2008 or 2009 were tested for sensitivity to myclobutanil, fenbuconazole, or difenoconazole. Growers provided management history of the sampled plots. Widespread shifts toward resistance to the three fungicides were noted, with mean effective concentration for 50% inhibition (EC(50)) values of 2.136, 0.786, and 0.187 μg/ml for myclobutanil, fenbuconazole, and difenoconazole, respectively. Cross resistance to the three fungicides was documented in high correlation (Spearman's r > 0.6) between mean EC(50) values for 14 orchards. Based on a 0.5-μg/ml threshold, 66 and 26% of isolates were resistant to myclobutanil and fenbuconazole, respectively, and 22% were cross resistant to the two fungicides. A significant between-year shift toward increased resistance was noted in two of three orchards surveyed in both years. Failure to use dormant copper sprays, older trees, larger orchards, orchards with ≤10 cultivars, and application of >4 DMI sprays were positively correlated (0.0001 < P < 0.05) with the incidence of resistant isolates. Isolates from orchards with >4 DMI sprays were four times as likely to be resistant to fenbuconazole (odds ratio = 4.57; P = 0.015). Isolates from orchards without dormant copper sprays were twice as likely to be cross-shifted toward resistance to all three fungicides (odds ratio = 1.76; P = 0.048). Results identify management practices that can reduce the risk of V. inaequalis developing resistance to DMI fungicides.

Relationship Between Crystalline Structure and Hardness of Ti-Si-N-O Coatings Fabricated by dc Sputtering

NASA Astrophysics Data System (ADS)

García-González, Leandro; Hernández-Torres, Julián; Mendoza-Barrera, Claudia; Meléndez-Lira, Miguel; García-Ramírez, Pedro J.; Martínez-Castillo, Jaime; Sauceda, Ángel; Herrera-May, Agustin L.; Muñoz Saldaña, Juan; Espinoza-Beltrán, Francisco J.

2008-08-01

Ti-Si-N-O coatings were deposited on AISI D2 tool steel and silicon substrates by dc reactive magnetron co-sputtering using a target of Ti-Si with a constant area ratio of 0.2. The substrate temperature was 400 °C and reactive atmosphere of nitrogen and argon. For all samples, argon flow was maintained constant at 25 sccm, while the flow of the nitrogen was varied to analyze the structural changes related to chemical composition and resistivity. According to results obtained by x-ray diffraction and stoichiometry calculations by x-ray energy dispersive spectroscopy the Ti-Si-N-O coatings contain two solid solutions. The higher crystalline part corresponds to titanium oxynitrure. Hardness tests on the coatings were carried out using the indentation work model and the hardness value was determined. Finally, the values of hardness were corroborated by nanoindentation test, and values of Young’s modulus and elastic recovery were discussed. We concluded that F2TSN sample ( F Ar = 25 sccm, F N = 5 sccm, P = 200 W, and P W = 8.9 × 10-3 mbar) presented the greatest hardness and the lowest resistivity values, due to its preferential crystalline orientation.

Association between Triglyceride to HDL-C Ratio (TG/HDL-C) and Insulin Resistance in Chinese Patients with Newly Diagnosed Type 2 Diabetes Mellitus.

PubMed

Ren, Xingxing; Chen, Zeng Ai; Zheng, Shuang; Han, Tingting; Li, Yangxue; Liu, Wei; Hu, Yaomin

2016-01-01

To explore the association between the triglyceride to HDL-C ratio (TG/HDL-C) and insulin resistance in Chinese patients with newly diagnosed type 2 diabetes mellitus. Patients with newly diagnosed type 2 diabetes mellitus (272 men and 288 women) were enrolled and divided into three groups according to TG/HDL-C tertiles. Insulin resistance was defined by homeostatic model assessment of insulin resistance (HOMA-IR). Demographic information and clinical characteristics were obtained. Spearman's correlation was used to estimate the association between TG/HDL-C and other variables. Multiple logistic regression analyses were adopted to obtain probabilities of insulin resistance. A receiver operating characteristic analysis was conducted to evaluate the ability of TG/HDL-C to discriminate insulin resistance. TG/HDL-C was associated with insulin resistance in Chinese patients with newly diagnosed T2DM (Spearman's correlation coefficient = 0.21, P < 0.01). Patients in the higher tertiles of TG/HDL-C had significantly higher HOMA-IR values than patients in the lower tertiles [T1: 2.68(1.74-3.70); T2: 2.96(2.29-4.56); T3: 3.09(2.30-4.99)]. Multiple logistic regression analysis showed that TG/HDL-C was significantly associated with HOMA-IR, and patients in the higher TG/HDL-C tertile had a higher OR than those in the lower TG/HDL-C tertile, after adjusting for multiple covariates including indices for central obesity [T1: 1; T2: 4.02(1.86-8.71); T3: 4.30(1.99-9.29)]. Following stratification of waist circumference into quartiles, the effect of TG/HDL-C on insulin resistance remained significant irrespective of waist circumference. TG/HDL-C was associated with insulin resistance independent of waist circumference. Whether it could be a surrogate marker for insulin resistance in Chinese patients with newly diagnosed type 2 diabetes mellitus still needs to be confirmed by more researches.

QSAR studies of macrocyclic diterpenes with P-glycoprotein inhibitory activity.

PubMed

Sousa, Inês J; Ferreira, Maria-José U; Molnár, Joseph; Fernandes, Miguel X

2013-02-14

Multidrug resistance (MDR) represents a major limitation for cancer chemotherapy. There are several mechanisms of MDR but the most important is associated with P-glycoprotein (P-gp) overexpression. The development of modulators of P-gp that are able to re-establish drug sensitivity of resistant cells has been considered a promising approach for overcoming MDR. Macrocyclic lathyrane and jatrophane-type diterpenes from Euphorbia species were found to be strong MDR reversing agents. In this study we applied quantitative structure-activity relationship (QSAR) methodology in order to identify the most relevant molecular features of macrocyclic diterpenes with P-gp inhibitory activity and to determine which structural modifications can be performed to improve their activity. Using experimental biological data at two concentrations (4 and 40 μg/ml), we developed a QSAR model for a set of 51 bioactive diterpenic compounds which includes lathyrane and jatrophane-type diterpenes and another model just for jatrophanes. The cross-validation correlation values for all diterpenes QSAR models developed for biological activities at compound concentrations of 4 and 40 μg/ml were 0.758 and 0.729, respectively. Regarding the prediction ability, we get R²(pred) values of 0.765 and 0.534 for biological activities at compound concentrations of 4 and 40 μg/ml, respectively. Applying the cross-validation test to jatrophanes QSAR models, we obtained 0.680 and 0.787 for biological activities at compound concentrations of 4 and 40 μg/ml concentrations, respectively. For the same concentrations, the obtained R²(pred) values for jatrophanes models were 0.541 and 0.534, respectively. The obtained models were statistically valid and showed high prediction ability. Copyright © 2012 Elsevier B.V. All rights reserved.

Modeling and Studying the Effect of Texture and Elastic Anisotropy of Copper Microstructure in Nanoscale Interconnects on Reliability in Integrated Circuits

NASA Astrophysics Data System (ADS)

Basavalingappa, Adarsh

Copper interconnects are typically polycrystalline and follow a lognormal grain size distribution. Polycrystalline copper interconnect microstructures with a lognormal grain size distribution were obtained with a Voronoi tessellation approach. The interconnect structures thus obtained were used to study grain growth mechanisms, grain boundary scattering, scattering dependent resistance of interconnects, stress evolution, vacancy migration, reliability life times, impact of orientation dependent anisotropy on various mechanisms, etc. In this work, the microstructures were used to study the impact of microstructure and elastic anisotropy of copper on thermal and electromigration induced failure. A test structure with copper and bulk moduli values was modeled to do a comparative study with the test structures with textured microstructure and elastic anisotropy. By subjecting the modeled test structure to a thermal stress by ramping temperature down from 400 °C to 100 °C, a significant variation in normal stresses and pressure were observed at the grain boundaries. This variation in normal stresses and hydrostatic stresses at the grain boundaries was found to be dependent on the orientation, dimensions, surroundings, and location of the grains. This may introduce new weak points within the metal line where normal stresses can be very high depending on the orientation of the grains leading to delamination and accumulation sites for vacancies. Further, the hydrostatic stress gradients act as a driving force for vacancy migration. The normal stresses can exceed certain grain orientation dependent critical threshold values and induce delamination at the copper and cap material interface, thereby leading to void nucleation and growth. Modeled test structures were subjected to a series of copper depositions at 250 °C followed by copper etch at 25 °C to obtain initial stress conditions. Then the modeled test structures were subjected to 100,000 hours ( 11.4 years) of simulated thermal stress at an elevated temperature of 150 °C. Vacancy migration due to concentration gradients, thermal gradients, and mechanical stress gradients were considered under the applied thermal stress. As a result, relatively high concentrations of vacancies were observed in the test structure due to a driving force caused by the pressure gradients resulting from the elastic anisotropy of copper. The grain growth mechanism was not considered in these simulations. Studies with two grain analysis demonstrated that the stress gradients developed will be severe when (100) grains are adjacent to (111) grains, therefore making them the weak points for potentially reliability failures. Ilan Blech discovered that electromigration occurs above a critical product of the current density and metal length, commonly referred as Blech condition. Electromigration stress simulations in this work were carried out by subjecting test structures to scaled current densities to overcome the Blech condition of (jL)crit for small dimensions of test structure and the low temperature stress condition used. Vacancy migration under the electromigration stress conditions was considered along with the vacancy migration induced stress evolution. A simple void growth model was used which assumes voids start to form when vacancies reach a critical level. Increase of vacancies in a localized region increases the resistance of the metal line. Considering a 10% increase in resistance as a failure criterion, the distributions of failure times were obtained for given electromigration stress conditions. Bimodal/multimodal failure distributions were obtained as a result. The sigma values were slightly lower than the ones commonly observed from experiments. The anisotropy of the elastic moduli of copper leads to the development of significantly different stress values which are dependent on the orientation of the grains. This results in some grains having higher normal stress than the others. This grain orientation dependent normal stress can reach a critical stress necessary to induce delamination at the copper and cap interface. Time taken to reach critical stress was considered as time to fail and distributions of failure times were obtained for structures with different grain orientations in the microstructure for different critical stress values. The sigma values of the failure distributions thus obtained for different constant critical stress values had a strong dependence of on the critical stress. It is therefore critical to use the appropriate critical stress value for the delamination of copper and cap interface. The critical stress necessary to overcome the local adhesion of the copper and the cap material interface is dependent on grain orientation of the copper. Simulations were carried out by considering grain orientation dependent critical normal stress values as failure criteria. The sigma value thus obtained with selected critical stress values were comparable to sigma values commonly observed from experiments.

Chemical passivation as a method of improving the electrochemical corrosion resistance of Co-Cr-based dental alloy.

PubMed

Rylska, Dorota; Sokołowski, Grzegorz; Sokołowski, Jerzy; Łukomska-Szymańska, Monika

2017-01-01

The purpose of the study was to evaluate corrosion resistance of Wirobond C® alloy after chemical passivation treatment. The alloy surface undergone chemical passivation treatment in four different media. Corrosion studies were carried out by means of electrochemical methods in saline solution. Corrosion effects were determined using SEM. The greatest increase in the alloy polarization resistance was observed for passive layer produced in Na2SO4 solution with graphite. The same layer caused the highest increase in corrosion current. Generally speaking, the alloy passivation in Na2SO4 solution with graphite caused a substantial improvement of the corrosion resistance. The sample after passivation in Na2SO4 solution without graphite, contrary to others, lost its protective properties along with successive anodic polarization cycles. The alloy passivation in Na3PO4 solution with graphite was the only one that caused a decrease in the alloy corrosion properties. The SEM studies of all samples after chemical passivation revealed no pit corrosion - in contrast to the sample without any modification. Every successive polarization cycle in anodic direction of pure Wirobond C® alloy enhances corrosion resistance shifting corrosion potential in the positive direction and decreasing corrosion current value. The chemical passivation in solutions with low pH values decreases susceptibility to electrochemical corrosion of Co-Cr dental alloy. The best protection against corrosion was obtained after chemical passivation of Wirobond C® in Na2SO4 solution with graphite. Passivation with Na2SO4 in solution of high pH does not cause an increase in corrosion resistance of WIROBOND C. Passivation process increases alloy resistance to pit corrosion.

Effect of vibration during fatiguing resistance exercise on subsequent muscle activity during maximal voluntary isometric contractions.

PubMed

McBride, Jeffrey M; Porcari, John P; Scheunke, Mark D

2004-11-01

This investigation was designed to determine if vibration during fatiguing resistance exercise would alter associated patterns of muscle activity. A cross-over design was employed with 8 subjects completing a resistance exercise bout once with a vibrating dumbbell (V) (44 Hz, 3 mm displacement) and once without vibration (NV). For both exercise bouts, 10 sets were performed with a load that induced concentric muscle failure during the 10th repetition. The appropriate load for each set was determined during a pretest. Each testing session was separated by 1 week. Electromyography (EMG) was obtained from the biceps brachii muscle at 12 different time points during a maximum voluntary contraction (MVC) at a 170 degrees elbow angle after each set of the dumbbell exercise. The time points were as follows: pre (5 minutes before the resistance exercise bout), T1-T10 (immediately following each set of resistance exercise), and post (15 minutes after the resistance exercise bout). EMG was analyzed for median power frequency (MPF) and maximum (mEMG). NV resulted in a significant decrease in MPF at T1-T4 (p < or 0.05) and a significant increase in mEMG at T2 during the MVC. V had an overall trend of lower mEMG in comparison to NV. The mEMG and MPF values associated with NV were similar to previously reported investigations. The lower mEMG values and the higher MPF of V in comparison to NV are undocumented. The EMG patterns observed with vibration may indicate a more efficient and effective recruitment of high threshold motor units during fatiguing contractions. This may indicate the usage of vibration with resistance exercise as an effective tool for strength training athletes.

[Factors influencing bonding fixed restorations].

PubMed

Medić, Vesna; Obradović-Djuricić, Kosovka

2008-01-01

Crown displacement often occurs because the features of tooth preparations do not counteract the forces directed against restorations. The purpose of this study was to evaluate the effect of preparation designs on retention and resistance of fixed restorations. The study was performed on 64 differently sized stainless steel dies. Also, caps which were used for evaluated retention were made of stainless steel for each die. After cementing the caps on experimental dies, measuring of necessary tensile forces to separate cemented caps from dies was done. Caps, which were made of a silver-palladium alloy with a slope of 600 to the longitudinal axis formed on the occlusal surface, were used for evaluating resistance. A sudden drop in load pressure recorded by the test machine indicated failure for that cap. A significant difference was found between the tensile force required to remove the caps from the dies with different length (p < 0.05) and different taper (p < 0.01). The greatest retentive strengths (2579.2 N and 2989.8 N) were noticed in experimental dies with the greatest length and smallest taper. No statistically significant (p > 0.05) differences were found between tensile loads for caps cemented on dies with different diameter. Although there was an apparent slight increase in resistance values for caps on dies with smaller tapers, the increase in resistance for those preparation designs was not statistically significant. There was a significant difference among the resistance values for caps on dies with different length (p < 0.01) and diameter (p < 0.05). In the light of the results obtained, it could be reasonably concluded that retention and resistance of the restoration is in inverse proportion to convergence angle of the prepared teeth. But, at a constant convergence angle, retention and resistance increase with rising length and diameter.

Synthesis and Characterization of Cefotaxime Conjugated Gold Nanoparticles and Their Use to Target Drug-Resistant CTX-M-Producing Bacterial Pathogens.

PubMed

Shaikh, Sibhghatulla; Rizvi, Syed Mohd Danish; Shakil, Shazi; Hussain, Talib; Alshammari, Thamir M; Ahmad, Waseem; Tabrez, Shams; Al-Qahtani, Mohammad H; Abuzenadah, Adel M

2017-09-01

Multidrug-resistance due to "β lactamases having the expanded spectrum" (ESBLs) in members of Enterobacteriaceae is a matter of continued clinical concern. CTX-M is among the most common ESBLs in Enterobacteriaceae family. In the present study, a nanoformulation of cefotaxime was prepared using gold nanoparticles to combat drug-resistance in ESBL producing strains. Here, two CTX-M-15 positive cefotaxime resistant bacterial strains (i.e., one Escherichia coli and one Klebsiella pneumoniae strain) were used for testing the efficacy of "cefotaxime loaded gold-nanoparticles." Bromelain was used for both reduction and capping in the process of synthesis of gold-nanoparticles. Thereafter, cefotaxime was conjugated onto it with the help of activator 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide. For characterization of both unconjugated and cefotaxime conjugated gold nanoparticles; UV-Visible spectroscopy, Scanning, and Transmission type Electron Microscopy methods accompanied with Dynamic Light Scattering were used. We used agar diffusion method plus microbroth-dilution method for the estimation of the antibacterial-activity and determination of minimum inhibitory concentration or MIC values, respectively. MIC values of cefotaxime loaded gold nanoparticles against E. coli and K. pneumoniae were obtained as 1.009 and 2.018 mg/L, respectively. These bacterial strains were completely resistant to cefotaxime alone. These results reinforce the utility of conjugating an old unresponsive antibiotic with gold nanoparticles to restore its efficacy against otherwise resistant bacterial pathogens. J. Cell. Biochem. 118: 2802-2808, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Utilizing of 2-D resistivity with geotechnical method for sediment mapping in Sungai Batu, Kedah

NASA Astrophysics Data System (ADS)

Taqiuddin, Z. M.; Rosli, S.; Nordiana, M. M.; Azwin, I. N.; Mokhtar, S.

2017-07-01

Sungai Batu is Lembah Bujang subdistrict, located at northern region of Peninsular Malaysia, recognized as an international cultural and commercial crossroad for 2000 years ago, and recorded as the oldest archaeological site in southeast Asia. The discovering of iron smelting area (1st-4th century) shows the evidence of important iron industry in Malay Peninsular to others civilization. Nowadays, a lot of interdisciplinary research was conducted in this area including geophysical prospect to understand the subsurface profile for this locality. Geophysical approach such as 2-D resistivity was performed with the main objective is to identify sediment deposit for this area. Three 2-D resistivity survey lines were design across borehole and data acquired using ABEM SAS4000 system with Pole-dipole array using 2.5 m minimum electrode spacing. The data obtained was process using Res2Dinv software to produce inversion model and Surfer10 software used for interpretation and correlation with respective borehole record. The 2-D resistivity inversion model shows that, the area dominated by clay soil with resistivity values of <50 Ωm while high resistivity values of >500 Ωm interpreted as hard layer. The saturated zone (<100 Ωm) were identified at depth of >25 m which consider large volume of soil deposit during sedimentation process. The correlation with the borehole record shows that clay profile distributed at depth of >20 m. The present of shale in certain borehole record indicate that the environment deposit is clam/stagnant water condition during the formation process which suspected controlled by the deposition process from the land deposit.

A systematic study on the effect of electron beam irradiation on structural, electrical, thermo-electric power and magnetic property of LaCoO3

NASA Astrophysics Data System (ADS)

Benedict, Christopher J.; Rao, Ashok; Sanjeev, Ganesh; Okram, G. S.; Babu, P. D.

2016-01-01

In this communication, the effect of electron beam irradiation on the structural, electrical, thermo-electric power and magnetic properties of LaCoO3 cobaltites have been investigated. Rietveld refinement of XRD data reveals that all samples are single phased with rhombohedral structure. Increase in electrical resistivity data is observed with increase in dosage of electron beam irradiation. Analysis of the measured electrical resistivity data indicates that the small polaron hopping model is operative in the high temperature regime for all samples. The Seebeck coefficient (S) of the pristine and the irradiated samples exhibits a crossover from positive to negative values, and a colossal value of Seebeck coefficient (32.65 mV/K) is obtained for pristine sample, however, the value of S decreases with increase in dosage of irradiation. The analysis of Seebeck coefficient data confirms that the small polaron hopping model is operative in the high temperature region. The magnetization results give clear evidence of increase in effective magnetic moment due to increase in dosage of electron beam irradiation.

Janus nanoparticles for stable microemulsions with ultra-low IFT values

NASA Astrophysics Data System (ADS)

Nava, Ilse; Diaz, Agustin; Yu, Yi-Hsien; Cheng, Zhengdong

2015-03-01

Janus particles are an influential type of materials used in foams, detergents, surfactants and cosmetics. Due to their demonstrated flexibility and non-toxicity, they have the potential to replace molecular surfactants, and thanks to their amphiphilicity, they can stabilize immiscible biphasic systems. Disk-based Janus particles best perform this stabilization. Graphene has been used to manufacture this class of particles; however, their fabrication in high yield by short and atomically economic syntheses remains a challenge. In this project we report the first synthesis of monolayer disks by a one pot reaction under microwave energy. Using a scalable method, these disks were synthesized, emulsified (in an oil/water system), and chemically reacted to obtain the Janus nanodisks with an efficient method. Our nanosheets production technique is a promising approach for the fabrication of Janus nanodisks via emulsification as it produces IFT (interfacial tension) values in a lower range than that of the molecular surfactants. These ultra-low values, in conjunction with the sheets' salt resistance, temperature resistance, and non-toxicity position Janus particles as the next generation of nanosurfactants.

Anomaly Monitoring Method for Key Components of Satellite

PubMed Central

Fan, Linjun; Xiao, Weidong; Tang, Jun

2014-01-01

This paper presented a fault diagnosis method for key components of satellite, called Anomaly Monitoring Method (AMM), which is made up of state estimation based on Multivariate State Estimation Techniques (MSET) and anomaly detection based on Sequential Probability Ratio Test (SPRT). On the basis of analysis failure of lithium-ion batteries (LIBs), we divided the failure of LIBs into internal failure, external failure, and thermal runaway and selected electrolyte resistance (R e) and the charge transfer resistance (R ct) as the key parameters of state estimation. Then, through the actual in-orbit telemetry data of the key parameters of LIBs, we obtained the actual residual value (R X) and healthy residual value (R L) of LIBs based on the state estimation of MSET, and then, through the residual values (R X and R L) of LIBs, we detected the anomaly states based on the anomaly detection of SPRT. Lastly, we conducted an example of AMM for LIBs, and, according to the results of AMM, we validated the feasibility and effectiveness of AMM by comparing it with the results of threshold detective method (TDM). PMID:24587703

Highly Stable K2SiF6:Mn4+@K2SiF6 Composite Phosphor with Narrow Red Emission for White LEDs.

PubMed

Huang, Lin; Liu, Yong; Yu, Jinbo; Zhu, Yiwen; Pan, Fengjuan; Xuan, Tongtong; Brik, Mikhail G; Wang, Chengxin; Wang, Jing

2018-05-30

Poor water resistance and nongreen synthesis remain great challenges for commercial narrow red-emitting phosphor A 2 MF 6 :Mn 4+ (A = alkali metal ion; M = Si, Ge, Ti) for solid-state lighting and display. We develop here a simple and green growth route to synthesize homogeneous red-emitting composite phosphor K 2 SiF 6 :Mn 4+ @K 2 SiF 6 (KSFM@KSF) with excellent water resistance and high efficiency without the usage of toxic and volatile hydrogen fluoride solution. After immersing into water for 6 h, the as-obtained water-resistant products maintain 76% of the original emission intensity, whereas the emission intensity of non-water-resistant ones steeply drops down to 11%. A remarkable result is that after having kept at 85% humidity and at 85 °C for 504 h (21 days), the emission intensity of the as-obtained water-resistant products is at 80-90%, from its initial value, which is 2-3 times higher than 30-40% for the non-water-resistant products. The surface deactivation-enabled growth mechanism for these phosphors was proposed and investigated in detail. We found that nontoxic H 3 PO 4 /H 2 O 2 aqueous solution promotes the releasing and decomposition of the surface [MnF 6 ] 2- ions and the transformation of the KSFM surface to KSF, which finally contributes to the homogeneous KSFM@KSF composite structure. This composite structure strategy was also successfully used to treat KSFM phosphor prepared by other methods. We believe that the results obtained in the present paper will open the pathway for the large-scale environmentally friendly synthesis of the excellent antimoisture narrow red-emitting A 2 MF 6 :Mn 4+ phosphor to be used for white light-emitting diode applications.

Influence of Step Annealing Temperature on the Microstructure and Pitting Corrosion Resistance of SDSS UNS S32760 Welds

NASA Astrophysics Data System (ADS)

Yousefieh, M.; Shamanian, M.; Saatchi, A.

2011-12-01

In the present work, the influence of step annealing heat treatment on the microstructure and pitting corrosion resistance of super duplex stainless steel UNS S32760 welds have been investigated. The pitting corrosion resistance in chloride solution was evaluated by potentiostatic measurements. The results showed that step annealing treatments in the temperature ranging from 550 to 1000 °C resulted in a precipitation of sigma phase and Cr2N along the ferrite/austenite and ferrite/ferrite boundaries. At this temperature range, the metastable pits mainly nucleated around the precipitates formed in the grain boundary and ferrite phase. Above 1050 °C, the microstructure contains only austenite and ferrite phases. At this condition, the critical pitting temperature of samples successfully arrived to the highest value obtained in this study.

Electrical resistivity of fluid methane multiply shock compressed to 147 GPa

NASA Astrophysics Data System (ADS)

Wang, Yi-Gao; Liu, Fu-Sheng; Liu, Qi-Jun; Wang, Wen-Peng

2018-01-01

Shock wave experiments were carried out to measure the electrical resistivity of fluid methane. The pressure range of 89-147 GPa and the temperature range from 1800 to 2600 K were achieved with a two-stage light-gas gun. We obtained a minimum electrical resistivity value of 4.5 × 10-2 Ω cm at pressure and temperature of 147 GPa and 2600 K, which is two orders of magnitude higher than that of hydrogen under similar conditions. The data are interpreted in terms of a continuous transition from insulator to semiconductor state. One possibility reason is chemical decomposition of methane in the shock compression process. Along density and temperature increase with Hugoniot pressure, dissociation of fluid methane increases continuously to form a H2-rich fluid.

Hydrodynamics and Heat Transfer in the Case of Combined Flow in a Annular Channel of Small Cross Section

NASA Astrophysics Data System (ADS)

Komov, A. T.; Varava, A. N.; Dedov, A. V.; Zakharenkov, A. V.; Boltenko, É. A.

2017-01-01

The present work is a continuation of experimental investigations conducted at the Moscow Power Engineering Institute (MPEI) on heat-transfer intensification. Brief descriptions of the working section and structure of intensifiers are given and their basic geometric parameters are enumerated. New systematized experimental data on the coefficients of hydraulic resistance and heat transfer in the regime of single-phase convection are given in an extended range of regime parameters and geometric characteristics of the intensifiers. Considerable increase in the heat-transfer coefficient as a function of the geometric characteristics of the intensifier has been established experimentally. The values of the relative fin height, at which these are the maxima of heat transfer and hydraulic resistance, have been established. Calculated dependences for the coefficient of hydraulic resistance and heat transfer have been obtained.

Research on the fragment impact resistance of a composite mast

NASA Astrophysics Data System (ADS)

Zhang, Wei; Wu, Chao; Yang, Wenshan; Xu, Shanshan; Ren, Shaofei

2011-09-01

Due to the unique structural mode and material property of a composite sandwich plate, related research such as fragment impact resistance of a composite mast is short of publication and urgent in this field. In this paper, the commonly accepted sandwich core board theory was modified. Damage caused by a fragment attack was simulated onto a sandwich plate model built with solid and shell elements. It was shown that shear failure and vast matrix cracking are the main reasons for outer coat damage, and tension failure and partial matrix cracking are the cause for inner coat damage. Additionally, according to complexities in actual sea battles, different work conditions of missile attacks were set. Ballistic limit values of different fragment sizes were also obtained, which provides references for enhancing the fragment impact resistance of a composite mast.

Optimization of droplets for UV-NIL using coarse-grain simulation of resist flow

NASA Astrophysics Data System (ADS)

Sirotkin, Vadim; Svintsov, Alexander; Zaitsev, Sergey

2009-03-01

A mathematical model and numerical method are described, which make it possible to simulate ultraviolet ("step and flash") nanoimprint lithography (UV-NIL) process adequately even using standard Personal Computers. The model is derived from 3D Navier-Stokes equations with the understanding that the resist motion is largely directed along the substrate surface and characterized by ultra-low values of the Reynolds number. By the numerical approximation of the model, a special finite difference method is applied (a coarse-grain method). A coarse-grain modeling tool for detailed analysis of resist spreading in UV-NIL at the structure-scale level is tested. The obtained results demonstrate the high ability of the tool to calculate optimal dispensing for given stamp design and process parameters. This dispensing provides uniform filled areas and a homogeneous residual layer thickness in UV-NIL.

Opto-electrochemical spectroscopy of metals in aqueous solutions

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

Habib, K., E-mail: khaledhabib@usa.net

In the present investigation, holographic interferometry was utilized for the first time to determine the rate change of the electrical resistance of aluminium samples during the initial stage of anodisation processes in aqueous solution. In fact, because the resistance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the resistance was called electrical resistance–emission spectroscopy. The anodisation process of the aluminium samples was carried out by electrochemical impedance spectroscopy (EIS) in different sulphuric acid concentrations (1.0%–2.5% H{sub 2}SO{sub 4}) at room temperature. In the meantime, the real time holographicmore » interferometry was used to determine the difference between the electrical resistance of two subsequent values, dR, as a function of the elapsed time of the EIS experiment for the aluminium samples in 1.0%, 1.5%, 2.0%, and 2.5% H{sub 2}SO{sub 4} solutions. The electrical resistance–emission spectra of the present investigation represent a detailed picture of not only the rate change of the electrical resistance throughout the anodisation processes but also the spectra represent the rate change of the growth of the oxide films on the aluminium samples in different solutions. As a result, a new spectrometer was developed based on the combination of the holographic interferometry and electrochemical impedance spectroscopy for studying in situ the electrochemical behavior of metals in aqueous solutions.« less

The influence of electrode and separator thickness on the cell resistance of symmetric cellulose-polypyrrole-based electric energy storage devices

NASA Astrophysics Data System (ADS)

Tammela, Petter; Olsson, Henrik; Strømme, Maria; Nyholm, Leif

2014-12-01

The influence of the cell design of symmetric polypyrrole and cellulose-based electric energy storage devices on the cell resistance was investigated using chronopotentiometric and ac impedance measurements with different separator and electrode thicknesses. The cell resistance was found to be dominated by the electrolyte and current collector resistances while the contribution from the composite electrode material was negligible. Due to the electrolyte within the porous electrodes thin separators could be used in combination with thick composite electrodes without loss of performance. The paper separator contributed with a resistance of ∼1.5 Ω mm-1 in a 1.0 M NaNO3 electrolyte and the tortuosity value for the separator was about 2.5. The contribution from the graphite foil current collectors was about ∼0.4-1.1 Ω and this contribution could not be reduced by using platinum foil current collectors due to larger contact resistances. The introduction of chopped carbon fibres into the electrode material or the application of pressure across the cells, however, decreased the charge transfer resistance significantly. As the present results demonstrate that cells with higher charge storage capacities but with the same cell resistance can be obtained by increasing the electrode thickness, the development of paper based energy storage devices is facilitated.

Ferromagnetic ordering in Mn-doped quantum wells GaAs-AlGaAs resulting from the virtual Anderson transition

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

Agrinskaya, N. V.; Berezovets, V. A.; Bouravlev, A.

We present our results obtained for Mn-doped GaAs quantum wells where the evidences of the ferromagnetic transition at relatively high temperatures were found at unusually small Mn concentrations. The observed values of hopping resistance at small temperatures evidenced that the samples are deep in the insulating regime. Thus the corresponding estimates of the overlapping integrals can hardly explain the large values of Curie temperatures T{sub c} ≃ 100 K. We develop a theoretical model qualitatively explaining the experimental results basing on the concept of virtual Anderson transition.

Electrical resistivity and geotechnical assessment of subgrade soils in southwestern part of Nigeria

NASA Astrophysics Data System (ADS)

Adebisi, N. O.; Ariyo, S. O.; Sotikare, P. B.

2016-07-01

The subgrade soils in areas underlain by the slightly Migmatized to Non-migmatized Metasedimentary and Metaigneous rocks of Southwestern Nigeria have been considerably investigated. However, a serious research which employs electrical resistivity method for insight into the profile development, as well as estimation of resistance to deformation for predicting the stability of flexible highway pavements is yet to be carried out. In this study, Vertical Electrical Sounding (VES) were carried out after a reconnaissance survey based on stable and unstable locations on the road. Index and strength tests related to road construction were also carried out on bulk samples obtained from stable and failed (unstable) locations of the Ago-Iwoye/Ishara highway. Results show mostly three (3) layers in the profiles with H, HK, and HKH curve types. The subgrade soils below the stable locations have better vertical and interval variations in the resistivities (89-1095 Ωm) to a depth of 3.4 m as against those from the failed portions. Those from the stable locations also have higher specific gravity (2.72), low-medium plasticity and A-2-6 kaolinitic clayey soils with higher compacted density (2090 kg/m3) compared to subgrade soils from the failed locations. On the basis of Califonia Bearing Ratio (CBR), subgrade soils at stable locations have greater strength than those obtained from failed locations. Estimated resistance to deformation (R-value) and resilient modulus (MR) proved to be the overriding parameters for predicting the stability of the flexible highway pavements.

The use of genomic information increases the accuracy of breeding value predictions for sea louse (Caligus rogercresseyi) resistance in Atlantic salmon (Salmo salar).

PubMed

Correa, Katharina; Bangera, Rama; Figueroa, René; Lhorente, Jean P; Yáñez, José M

2017-01-31

Sea lice infestations caused by Caligus rogercresseyi are a main concern to the salmon farming industry due to associated economic losses. Resistance to this parasite was shown to have low to moderate genetic variation and its genetic architecture was suggested to be polygenic. The aim of this study was to compare accuracies of breeding value predictions obtained with pedigree-based best linear unbiased prediction (P-BLUP) methodology against different genomic prediction approaches: genomic BLUP (G-BLUP), Bayesian Lasso, and Bayes C. To achieve this, 2404 individuals from 118 families were measured for C. rogercresseyi count after a challenge and genotyped using 37 K single nucleotide polymorphisms. Accuracies were assessed using fivefold cross-validation and SNP densities of 0.5, 1, 5, 10, 25 and 37 K. Accuracy of genomic predictions increased with increasing SNP density and was higher than pedigree-based BLUP predictions by up to 22%. Both Bayesian and G-BLUP methods can predict breeding values with higher accuracies than pedigree-based BLUP, however, G-BLUP may be the preferred method because of reduced computation time and ease of implementation. A relatively low marker density (i.e. 10 K) is sufficient for maximal increase in accuracy when using G-BLUP or Bayesian methods for genomic prediction of C. rogercresseyi resistance in Atlantic salmon.

Microbial modeling of thermal resistance of Alicyclobacillus acidoterrestris CRA7152 spores in concentrated orange juice with nisin addition

PubMed Central

Peña, Wilmer Edgard Luera; de Massaguer, Pilar Rodriguez; Teixeira, Luciano Quintão

2009-01-01

The nisin effect on thermal death of Alicyclobacillus acidoterrestris CRA 7152 spores in concentrated orange juice (64°Brix) was studied. Concentrations of 0, 50, 75 and 100 IU of nisin/ml juice, at temperatures of 92, 95, 98 and 102°C were evaluated. The quadratic polynomial model was used to analyze the effects of the factors and their interaction. Verification of surviving spores was carried out through plating in K medium (pH 3.7). The results showed that the D values without nisin addition were 25.5, 12.9, 6.1 and 2.3 min for 92, 95, 98 and 102°C respectively. With addition of nisin into the juice there was a drop of heat resistance as the concentration was increased at a same temperature. With 30, 50, 75, 100 and 150 IU/ml at 95°C, the D values were 12.34, 11.38, 10.49, 9.49 and 9.42 min respectively, showing that a decrease in the D value up to 27% can be obtained. The second order polynomial model established with r2 = 0.995 showed that the microorganism resistance was affected by the action of temperature followed by the nisin concentration. Nisin therefore is an alternative for reducing the rigor of the A. acidoterrestris CRA 7152 thermal treatment. PMID:24031405

Development of microheaters for gas sensor with an AT-Mega 8535 temperature controller using a PWM (pulse width modulation) method

NASA Astrophysics Data System (ADS)

Megayanti, Meti; Panatarani, Camellia; Joni, I. Made

2016-03-01

Microheater is the main component in gas sensor characterized by their sensitivity, selectivity, and time response of gas sensor which is depend on the microheater temperature stability. A Cu microheater was developed and utilized AT-Mega 8535 controller using a PWM (pulse width modulation) method. This control system is interfaced to the PC to observe the real time temperature response of the microheater. Three initial resistance (R0) variations of microheater were developed in an open loop control system. The power characteristic of designed microheater depends on the specified microheater initial resistance. The smaller R0, the less power required to reach a temperature setting value. The developed microheater was designed to reach a temperature setting value of 250°C having resistance 0.531 Ω for 1.979 Watt and 0.265 Ω for 1.072 Watt respectively. The results of the investigation on the control performances shows microheater-control system achieved operating temperature up to 250°C. The response of the temperature control shows smallest R0 resulted in a high stability with short settling time, short delay time and small ripple for temperature setting values higher than 150°C. The obtained error of microheater temperature with R0 = 0.265 is 8.596 %. It is concluded that the developed microheater can be utilized as a component of a gas sensor.

Variable number of tandem repeat profiles and antimicrobial resistance patterns of Staphylococcus haemolyticus strains isolated from blood cultures in children.

PubMed

Hosseinkhani, Faride; Jabalameli, Fereshteh; Nodeh Farahani, Narges; Taherikalani, Morovat; van Leeuwen, Willem B; Emaneini, Mohammad

2016-03-01

Staphylococcus haemolyticus is a healthcare-associated pathogen and can cause a variety of lifethreatening infections. Additionally, multi-drug resistance (MDR), in particular methicillin-resistant S. haemolyticus (MRSH) isolates, have emerged. Dissemination of such strains can be of great concern in the hospital environment. A total number of 20S. haemolyticus isolates from blood cultures obtained from children were included in this study. A high prevalence of MDR-MRSH isolates with high MIC values to vancomycin was found and 35% of the isolates were intermediate resistant to vancomycin. Multilocus variable number of tandem repeats analysis (MLVF) revealed 5 MLVF types among 20 isolates of S. haemolyticus. Twelve isolates shared the same MLVF type and were isolated from different wards in a pediatric hospital in Iran. This is a serious alarm for infection control; i.e. in the absence of adequate infection diagnostics and infection control guidelines, these resistant strains can spread to other sectors of a hospital and possibly among the community. Copyright © 2015 Elsevier B.V. All rights reserved.

Phytochemical analysis and cytotoxicity towards multidrug-resistant leukemia cells of essential oils derived from Lebanese medicinal plants.

PubMed

Saab, Antoine M; Guerrini, Alessandra; Sacchetti, Gianni; Maietti, Silvia; Zeino, Maʼen; Arend, Joachim; Gambari, Roberto; Bernardi, Francesco; Efferth, Thomas

2012-12-01

Juniperus excelsa fruit essential oil as well as J. oxycedrus, Cedrus libani, and Pinus pinea wood essential oils have been obtained with yields between 2.2 ± 0.3 % to 3.4 ± 0.5 % and analyzed by gas chromatography. Sesquiterpenes mainly characterized C. libani and J. oxycedrus essential oils, while in P. pinea and J. excelsa, monoterpenes were the most abundant compounds. In J. oxycedrus, cis-calamenene (7.8 %), cuparene (3.8 %), and cis-thujopsenal (2.0 %) have been detected for the first time. The cytotoxic activity of these essential oils against drug-sensitive CCRF-CEM and multidrug-resistant P-glycoprotein-expressing CEM/ADR5000 leukemia cells has been investigated (IC₅₀ values: 29.46 to 61.54 µg/mL). Remarkably, multidrug-resistant CEM/ADR5000 cells did not reveal cross-resistance, indicating that these essential oils might be useful to treat otherwise drug-resistant and refractory tumors. Georg Thieme Verlag KG Stuttgart · New York.

Detection of Shallow Buried Archaeological Remains Structure using 2-D Resistivity Method at Sungai Batu, Lembah Bujang, Kedah

NASA Astrophysics Data System (ADS)

Ismail, Nurina; Nordiana, M. M.; Saidin, M.; Masnan, S. S. K.; Abir, I. A.

2018-04-01

In an archaeological study, 2-D resistivity becomes important tools for the scientific investigation and also can be applied to map shallow subsurface structures at the archaeological site. The main purpose of the research is to locate the shallow buried archaeological remains structure in the area of Sungai Batu, Lembah Bujang, Kedah (Malaysia). Resistivity surveys have been applied using a Pole-dipole array with both 5 survey lines for SB1 and SB2 sites using 0.75 m electrode spacing. Both results revealed high resistivity zone with ≥ 3000 Ωm at a depth ranging from 0-1.5 m at the study area. SB1 site conducting an excavation to validate the result obtain while SB2 is not conducting any excavation. Besides that, the other characteristics of the buried archaeological remains are indicated as mound area and there is exposed remain found on top of the surface. Based on the archaeological evidence, the higher resistivity value indicates the interesting anomaly which is clay bricks for archaeological excavation.

Source of the slippage in the universal joints of the Hoffmann external fixator.

PubMed

Drijber, F L; Finlay, J B; Moroz, T K; Rorabeck, C H

1990-01-01

An investigation was conducted to determine what improvements in the resistance to slippage could be obtained in selected interfaces (rod/clip torsional, cheek/bowl and cheek/clip) of the Hoffmann external fixator. The modification involved changing the standard wing-nut clamp for a bolt with a thread of 7 mm and a 1 mm pitch and placing an FAG 28-303 thrust-bearing (needle roller and cage assembly) between the bolt and the cheek. The results showed a significant improvement in the slippage values of all interfaces; increases of approximately six times were obtained at all torque values of the wing-nut clamp or fastener tested. Such improvements would markedly increase the reliability of external fixation systems and thus reduce the incidence of loss-of-reduction of fracture due to slippage of the universal joint.

J-substitution algorithm in magnetic resonance electrical impedance tomography (MREIT): phantom experiments for static resistivity images.

PubMed

Khang, Hyun Soo; Lee, Byung Il; Oh, Suk Hoon; Woo, Eung Je; Lee, Soo Yeol; Cho, Min Hyoung; Kwon, Ohin; Yoon, Jeong Rock; Seo, Jin Keun

2002-06-01

Recently, a new static resistivity image reconstruction algorithm is proposed utilizing internal current density data obtained by magnetic resonance current density imaging technique. This new imaging method is called magnetic resonance electrical impedance tomography (MREIT). The derivation and performance of J-substitution algorithm in MREIT have been reported as a new accurate and high-resolution static impedance imaging technique via computer simulation methods. In this paper, we present experimental procedures, denoising techniques, and image reconstructions using a 0.3-tesla (T) experimental MREIT system and saline phantoms. MREIT using J-substitution algorithm effectively utilizes the internal current density information resolving the problem inherent in a conventional EIT, that is, the low sensitivity of boundary measurements to any changes of internal tissue resistivity values. Resistivity images of saline phantoms show an accuracy of 6.8%-47.2% and spatial resolution of 64 x 64. Both of them can be significantly improved by using an MRI system with a better signal-to-noise ratio.

Larson-Miller Constant of Heat-Resistant Steel

NASA Astrophysics Data System (ADS)

Tamura, Manabu; Abe, Fujio; Shiba, Kiyoyuki; Sakasegawa, Hideo; Tanigawa, Hiroyasu

2013-06-01

Long-term rupture data for 79 types of heat-resistant steels including carbon steel, low-alloy steel, high-alloy steel, austenitic stainless steel, and superalloy were analyzed, and a constant for the Larson-Miller (LM) parameter was obtained in the current study for each material. The calculated LM constant, C, is approximately 20 for heat-resistant steels and alloys except for high-alloy martensitic steels with high creep resistance, for which C ≈ 30 . The apparent activation energy was also calculated, and the LM constant was found to be proportional to the apparent activation energy with a high correlation coefficient, which suggests that the LM constant is a material constant possessing intrinsic physical meaning. The contribution of the entropy change to the LM constant is not small, especially for several martensitic steels with large values of C. Deformation of such martensitic steels should accompany a large entropy change of 10 times the gas constant at least, besides the entropy change due to self-diffusion.

Transient and Sharvin resistances of Luttinger liquids

NASA Astrophysics Data System (ADS)

Kloss, Thomas; Weston, Joseph; Waintal, Xavier

2018-04-01

Although the intrinsic conductance of an interacting one-dimensional system is renormalized by the electron-electron correlations, it has been known for some time that this renormalization is washed out by the presence of the (noninteracting) electrodes to which the wire is connected. Here, we study the transient conductance of such a wire: a finite voltage bias is suddenly applied across the wire and we measure the current before it has enough time to reach its stationary value. These calculations allow us to extract the Sharvin (contact) resistance of Luttinger and Fermi liquids. In particular, we find that a perfect junction between a Fermi liquid electrode and a Luttinger liquid electrode is characterized by a contact resistance that consists of half the quantum of conductance in series with half the intrinsic resistance of an infinite Luttinger liquid. These results were obtained using two different methods: a dynamical Hartree-Fock approach and a self-consistent Boltzmann approach. Although these methods are formally approximate, we find a perfect match with the exact results of Luttinger/Fermi liquid theory.

Toward advanced gamma rays radiation resistance and shielding efficiency with phthalonitrile resins and composites

NASA Astrophysics Data System (ADS)

Derradji, Mehdi; Zegaoui, Abdeldjalil; Xu, Yi-Le; Wang, An-ran; Dayo, Abdul Qadeer; Wang, Jun; Liu, Wen-bin; Liu, Yu-Guang; Khiari, Karim

2018-04-01

The phthalonitrile resins have claimed the leading place in the field of high performance polymers thanks to their combination of outstanding properties. The present work explores for the first time the gamma rays radiation resistance and shielding efficiency of the phthalonitrile resins and its related tungsten-reinforced nanocomposites. The primary goal of this research is to define the basic behavior of the phthalonitrile resins under highly ionizing gamma rays. The obtained results confirmed that the neat phthalonitrile resins can resist absorbed doses as high as 200 kGy. Meanwhile, the remarkable shielding efficiency of the phthalonitrile polymers was confirmed to be easily improved by preparing lead-free nanocomposites. In fact, the gamma rays screening ratio reached the exceptional value of 42% for the nanocomposites of 50 wt% of nano-tungsten loading. Thus, this study confirms that the remarkable performances of the phthalonitrile resins are not limited to the thermal and mechanical properties and can be extended to the gamma rays radiation and shielding resistances.

Electrical, optical and structural properties of FTO thin films fabricated by spray ultrasonic nebulizer technique from SnCl4 precursor

NASA Astrophysics Data System (ADS)

Lalasari, Latifa Hanum; Arini, Tri; Andriyah, Lia; Firdiyono, F.; Yuwono, Akhmad Herman

2018-05-01

Thin films of fluorine-doped tin oxide on glass were prepared by spray ultrasonic nebulizer technique from an economic anhydrous tin (IV) chloride (SnCl4) precursor. The effect of deposition time on the structural, electrical and optical properties of tin oxide thin films was investigated. This research a purpose to find an optimum deposition time during spray pyrolysis technique in order to produce FTO with the desired characteristics. For this purpose, soda lime glasses are heated at 350 °C on deposition time of 10, 15, 20 and 25 minutes. NH4F was doped at a ratio of 2 wt% in the SnCl4 precursor and methanol solvent. The results revealed that longer deposition times created decreased the electrical resistivity and optical transmittance of FTO layers. The highest optical transmittance was 84.808% and the lowest resistivity was 4.01×10-5 Ω.cm, obtained from FTO glass subjected to a 15-minute deposition time at deposition temperature of 350 °C. This is accordance to the TCO conductive glass requirements for the minimum resistivity value on scale 10-4 Ω.cm and optical transmittance value of 80-85%.

Effects of pH Value of the Electrolyte and Glycine Additive on Formation and Properties of Electrodeposited Zn-Fe Coatings

PubMed Central

2013-01-01

Environmentally friendly and cyanide-free sulfate bath under continuous current and the corrosion behavior of electrodeposits of zinc-iron alloys were studied by means of electrochemical tests in a solution of 3.5% NaCl in presence and absence of glycine. The effects of pH on the quality of Zn-Fe coatings were investigated in order to improve uniformity and corrosion protection performance of the coating films. The deposit morphology was analyzed using scanning electron microscopy (SEM), and X-ray diffraction (XRD) was used to determine the preferred crystallographic orientations of the deposits. It was found that the uniformity and corrosion resistance of Zn-Fe coating films were strongly associated with pH of the coating electrolyte. To obtain the effect of pH on the film quality and corrosion performances of the films, the corrosion test was performed with potentiodynamic anodic polarization method. It was also observed that uniformity and corrosion resistivity of the coating films were decreased towards pH = 5 and then improved with increasing pH value of the electrolyte. The presence of glycine in the plating bath decreases the corrosion resistance of Zn-Fe coatings. PMID:23844388

Exploration of the susceptibility of AChE from the poultry red mite Dermanyssus gallinae (Acari: Mesostigmata) to organophosphates in field isolates from France.

PubMed

Roy, Lise; Chauve, Claude; Delaporte, Jean; Inizan, Gilbert; Buronfosse, Thierry

2009-06-01

The red fowl mite Dermanyssus gallinae (De Geer, 1778) is a hematophagous mite species, which is very commonly found in layer facilities in Europe. The economic and animal health impact of this parasite is quite important. In laying hen houses, organophosphates are almost the only legally usable chemicals. Detecting a target resistance can be useful in order to limit the emergence of resistant populations. The acetylcholinesterase (AChE) activity and the enzyme sensitivity to paraoxon was investigated in 39 field samples and compared to a susceptible reference strain (SSK). Insensitivity factor values (expressed as IC50 ratio) obtained from field isolates compared to SSK revealed some polymorphism but not exceeding a 6-fold difference. The kinetic characteristics of AChE from some field samples showed some difference in KM values for acetylthiocholine and inhibition kinetics performed with diethyl paraoxon exhibited a 5.5-fold difference in the bimolecular rate constant in one field isolate. Taken together, these data suggested that differences in AChE susceptibility to organophosphates may exist in D. gallinae but no resistant population was found.

Design of a Soil Cutting Resistance Sensor for Application in Site-Specific Tillage

PubMed Central

Agüera, Juan; Carballido, Jacob; Gil, Jesús; Gliever, Chris J.; Perez-Ruiz, Manuel

2013-01-01

One objective of precision agriculture is to provide accurate information about soil and crop properties to optimize the management of agricultural inputs to meet site-specific needs. This paper describes the development of a sensor equipped with RTK-GPS technology that continuously and efficiently measures soil cutting resistance at various depths while traversing the field. Laboratory and preliminary field tests verified the accuracy of this prototype soil strength sensor. The data obtained using a hand-operated soil cone penetrometer was used to evaluate this field soil compaction depth profile sensor. To date, this sensor has only been tested in one field under one gravimetric water content condition. This field test revealed that the relationships between the soil strength profile sensor (SSPS) cutting force and soil cone index values are assumed to be quadratic for the various depths considered: 0–10, 10–20 and 20–30 cm (r2 = 0.58, 0.45 and 0.54, respectively). Soil resistance contour maps illustrated its practical value. The developed sensor provides accurate, timely and affordable information on soil properties to optimize resources and improve agricultural economy. PMID:23666127

Structure and conductivity of nanostructured YBCO ceramics

NASA Astrophysics Data System (ADS)

Palchayev, D. K.; Gadzhimagomedov, S. Kh; Murlieva, Zh Kh; Rabadanov, M. Kh; Emirov, R. M.

2017-12-01

Superconducting nanostructured ceramics based on YBa2Cu3O7-δ were made of nanopowder obtained by burning nitrate-organic precursors. The structure, morphology, electrical resistivity, and density of ceramics were studied. Various porosity values of the ceramics were achieved by preliminary heat treatment of the nanopowder. The features of conductivity and the reason for increase of the of the superconducting transition temperature in these materials are discussed.

Generating porosity spectrum of carbonate reservoirs using ultrasonic imaging log

NASA Astrophysics Data System (ADS)

Zhang, Jie; Nie, Xin; Xiao, Suyun; Zhang, Chong; Zhang, Chaomo; Zhang, Zhansong

2018-03-01

Imaging logging tools can provide us the borehole wall image. The micro-resistivity imaging logging has been used to obtain borehole porosity spectrum. However, the resistivity imaging logging cannot cover the whole borehole wall. In this paper, we propose a method to calculate the porosity spectrum using ultrasonic imaging logging data. Based on the amplitude attenuation equation, we analyze the factors affecting the propagation of wave in drilling fluid and formation and based on the bulk-volume rock model, Wyllie equation and Raymer equation, we establish various conversion models between the reflection coefficient β and porosity ϕ. Then we use the ultrasonic imaging logging and conventional wireline logging data to calculate the near-borehole formation porosity distribution spectrum. The porosity spectrum result obtained from ultrasonic imaging data is compared with the one from the micro-resistivity imaging data, and they turn out to be similar, but with discrepancy, which is caused by the borehole coverage and data input difference. We separate the porosity types by performing threshold value segmentation and generate porosity-depth distribution curves by counting with equal depth spacing on the porosity image. The practice result is good and reveals the efficiency of our method.

A comparative study of the refractive index of silk protein thin films towards biomaterial based optical devices

NASA Astrophysics Data System (ADS)

Bucciarelli, A.; Mulloni, V.; Maniglio, D.; Pal, R. K.; Yadavalli, V. K.; Motta, A.; Quaranta, A.

2018-04-01

Over the last two decades, silk fibroin has been exploited as a versatile optical material in biological applications due to a combination of unique properties. Recently, protocols have been developed to produce a silk fibroin negative tone resist that is UV crosslinkable, thereby allowing micro and nanoscale patterning of the protein using traditional photolithographic tools. The same protocol has been applied to the silk protein sericin to develop a sericin resist. Despite the immense potential of these biomaterials to develop micro optical patterns on silicon and glass surfaces, as well as self-standing components, their refractive indexes are not well characterized. In this work, optimizing a method to obtain extremely smooth, thin films, the refractive index (RI) of fibroin and sericin proteins and resists were characterized using ellipsometry. The parameters of the Sellmeier and Cauchy dispersion laws have been determined to obtain the RI over a large wavelength range. A complete morphological study of the films has been conducted. In addition, the effect of solvent on the optical properties of silk fibroin and sericin thin films are reported, with differences in values explained by examining the change in the protein secondary structure.

Toxicology Analysis of Tissue-Mimicking Phantom Made From Gelatin

NASA Astrophysics Data System (ADS)

Dolbashid, A. S.; Hamzah, N.; Zaman, W. S. W. K.; Mokhtar, M. S.

2017-06-01

Skin phantom mimics the biological skin tissues as it have the ability to respond to changes in its environment. The development of tissue-mimicking phantom could contributes towards the reduce usage of animal in cosmetics and pharmacokinetics. In this study, the skin phantoms made from gelatin were tested with four different commonly available cosmetic products to determine the toxicity of each substance. The four substances used were; mercury-based whitening face cream, carcinogenic liquid make-up foundation, paraben-based acne cleanser, and organic lip balm. Toxicity test were performed on all of the phantoms. For toxicity testing, topographical and electrophysiological changes of the phantoms were evaluated. The ability of each respective phantom to react with mild toxic substances and its electrical resistance were analysed in to determine the toxicity of all the phantom models. Four-electrode method along with custom made electrical impedance analyser was used to differentiate electrical resistance between intoxicated phantom and non-intoxicated phantom in this study. Electrical resistance values obtained from the phantom models were significantly higher than the control group. The result obtained suggests the phantom as a promising candidate to be used as alternative for toxicology testing in the future.

A revised surface resistance parameterisation for estimating latent heat flux from remotely sensed data

NASA Astrophysics Data System (ADS)

Song, Yi; Wang, Jiemin; Yang, Kun; Ma, Mingguo; Li, Xin; Zhang, Zhihui; Wang, Xufeng

2012-07-01

Estimating evapotranspiration (ET) is required for many environmental studies. Remote sensing provides the ability to spatially map latent heat flux. Many studies have developed approaches to derive spatially distributed surface energy fluxes from various satellite sensors with the help of field observations. In this study, remote-sensing-based λE mapping was conducted using a Landsat Thematic Mapper (TM) image and an Enhanced Thematic Mapper Plus (ETM+) image. The remotely sensed data and field observations employed in this study were obtained from Watershed Allied Telemetry Experimental Research (WATER). A biophysics-based surface resistance model was revised to account for water stress and temperature constraints. The precision of the results was validated using 'ground truth' data obtained by eddy covariance (EC) system. Scale effects play an important role, especially for parameter optimisation and validation of the latent heat flux (λE). After considering the footprint of EC, the λE derived from the remote sensing data was comparable to the EC measured value during the satellite's passage. The results showed that the revised surface resistance parameterisation scheme was useful for estimating the latent heat flux over cropland in arid regions.

Reliability of Strength Testing using the Advanced Resistive Exercise Device and Free Weights

NASA Technical Reports Server (NTRS)

English, Kirk L.; Loehr, James A.; Laughlin, Mitzi A.; Lee, Stuart M. C.; Hagan, R. Donald

2008-01-01

The Advanced Resistive Exercise Device (ARED) was developed for use on the International Space Station as a countermeasure against muscle atrophy and decreased strength. This investigation examined the reliability of one-repetition maximum (1RM) strength testing using ARED and traditional free weight (FW) exercise. Methods: Six males (180.8 +/- 4.3 cm, 83.6 +/- 6.4 kg, 36 +/- 8 y, mean +/- SD) who had not engaged in resistive exercise for at least six months volunteered to participate in this project. Subjects completed four 1RM testing sessions each for FW and ARED (eight total sessions) using a balanced, randomized, crossover design. All testing using one device was completed before progressing to the other. During each session, 1RM was measured for the squat, heel raise, and deadlift exercises. Generalizability (G) and intraclass correlation coefficients (ICC) were calculated for each exercise on each device and were used to predict the number of sessions needed to obtain a reliable 1RM measurement (G . 0.90). Interclass reliability coefficients and Pearson's correlation coefficients (R) also were calculated for the highest 1RM value (1RM9sub peak)) obtained for each exercise on each device to quantify 1RM relationships between devices.

Quality Test of Flexible Flat Cable (FFC) With Short Open Test Using Law Ohm Approach through Embedded Fuzzy Logic Based On Open Source Arduino Data Logger

NASA Astrophysics Data System (ADS)

Rohmanu, Ajar; Everhard, Yan

2017-04-01

A technological development, especially in the field of electronics is very fast. One of the developments in the electronics hardware device is Flexible Flat Cable (FFC), which serves as a media liaison between the main boards with other hardware parts. The production of Flexible Flat Cable (FFC) will go through the process of testing and measuring of the quality Flexible Flat Cable (FFC). Currently, the testing and measurement is still done manually by observing the Light Emitting Diode (LED) by the operator, so there were many problems. This study will be made of test quality Flexible Flat Cable (FFC) computationally utilize Open Source Embedded System. The method used is the measurement with Short Open Test method using Ohm’s Law approach to 4-wire (Kelvin) and fuzzy logic as a decision maker measurement results based on Open Source Arduino Data Logger. This system uses a sensor current INA219 as a sensor to read the voltage value thus obtained resistance value Flexible Flat Cable (FFC). To get a good system we will do the Black-box testing as well as testing the accuracy and precision with the standard deviation method. In testing the system using three models samples were obtained the test results in the form of standard deviation for the first model of 1.921 second model of 4.567 and 6.300 for the third model. While the value of the Standard Error of Mean (SEM) for the first model of the model 0.304 second at 0.736 and 0.996 of the third model. In testing this system, we will also obtain the average value of the measurement tolerance resistance values for the first model of - 3.50% 4.45% second model and the third model of 5.18% with the standard measurement of prisoners and improve productivity becomes 118.33%. From the results of the testing system is expected to improve the quality and productivity in the process of testing Flexible Flat Cable (FFC).

Diversity of Survival Patterns among Escherichia coli O157:H7 Genotypes Subjected to Food-Related Stress Conditions.

PubMed

Elhadidy, Mohamed; Álvarez-Ordóñez, Avelino

2016-01-01

The purpose of this study was to evaluate the resistance patterns to food-related stresses of Shiga toxin producing Escherichia coli O157:H7 strains belonging to specific genotypes. A total of 33 E. coli O157:H7 strains were exposed to seven different stress conditions acting as potential selective pressures affecting the transmission of E. coli O157:H7 to humans through the food chain. These stress conditions included cold, oxidative, osmotic, acid, heat, freeze-thaw, and starvation stresses. The genotypes used for comparison included lineage-specific polymorphism, Shiga-toxin-encoding bacteriophage insertion sites, clade type, tir (A255T) polymorphism, Shiga toxin 2 subtype, and antiterminator Q gene allele. Bacterial resistance to different stressors was calculated by determining D-values (times required for inactivation of 90% of the bacterial population), which were then subjected to univariate and multivariate analyses. In addition, a relative stress resistance value, integrating resistance values to all tested stressors, was calculated for each bacterial strain and allowed for a ranking-type classification of E. coli O157:H7 strains according to their environmental robustness. Lineage I/II strains were found to be significantly more resistant to acid, cold, and starvation stress than lineage II strains. Similarly, tir (255T) and clade 8 encoding strains were significantly more resistant to acid, heat, cold, and starvation stress than tir (255A) and non-clade 8 strains. Principal component analysis, which allows grouping of strains with similar stress survival characteristics, separated strains of lineage I and I/II from strains of lineage II, which in general showed reduced survival abilities. Results obtained suggest that lineage I/II, tir (255T), and clade 8 strains, which have been previously reported to be more frequently associated with human disease cases, have greater multiple stress resistance than strains of other genotypes. The results from this study provide a better insight into how selective pressures encountered through the food chain may play a role in the epidemiology of STEC O157:H7 through controlling the transmission of highly adapted strains to humans.

Diversity of Survival Patterns among Escherichia coli O157:H7 Genotypes Subjected to Food-Related Stress Conditions

PubMed Central

Elhadidy, Mohamed; Álvarez-Ordóñez, Avelino

2016-01-01

The purpose of this study was to evaluate the resistance patterns to food-related stresses of Shiga toxin producing Escherichia coli O157:H7 strains belonging to specific genotypes. A total of 33 E. coli O157:H7 strains were exposed to seven different stress conditions acting as potential selective pressures affecting the transmission of E. coli O157:H7 to humans through the food chain. These stress conditions included cold, oxidative, osmotic, acid, heat, freeze-thaw, and starvation stresses. The genotypes used for comparison included lineage-specific polymorphism, Shiga-toxin-encoding bacteriophage insertion sites, clade type, tir (A255T) polymorphism, Shiga toxin 2 subtype, and antiterminator Q gene allele. Bacterial resistance to different stressors was calculated by determining D-values (times required for inactivation of 90% of the bacterial population), which were then subjected to univariate and multivariate analyses. In addition, a relative stress resistance value, integrating resistance values to all tested stressors, was calculated for each bacterial strain and allowed for a ranking-type classification of E. coli O157:H7 strains according to their environmental robustness. Lineage I/II strains were found to be significantly more resistant to acid, cold, and starvation stress than lineage II strains. Similarly, tir (255T) and clade 8 encoding strains were significantly more resistant to acid, heat, cold, and starvation stress than tir (255A) and non-clade 8 strains. Principal component analysis, which allows grouping of strains with similar stress survival characteristics, separated strains of lineage I and I/II from strains of lineage II, which in general showed reduced survival abilities. Results obtained suggest that lineage I/II, tir (255T), and clade 8 strains, which have been previously reported to be more frequently associated with human disease cases, have greater multiple stress resistance than strains of other genotypes. The results from this study provide a better insight into how selective pressures encountered through the food chain may play a role in the epidemiology of STEC O157:H7 through controlling the transmission of highly adapted strains to humans. PMID:27014242

Proliferation resistance assessment of various methods of spent nuclear fuel storage and disposal

NASA Astrophysics Data System (ADS)

Kollar, Lenka

Many countries are planning to build or already are building new nuclear power plants to match their growing energy needs. Since all nuclear power plants handle nuclear materials that could potentially be converted and used for nuclear weapons, they each present a nuclear proliferation risk. Spent nuclear fuel presents the largest build-up of nuclear material at a power plant. This is a proliferation risk because spent fuel contains plutonium that can be chemically separated and used for a nuclear weapon. The International Atomic Energy Agency (IAEA) safeguards spent fuel in all non-nuclear weapons states that are party to the Non-Proliferation Treaty. Various safeguards methods are in use at nuclear power plants and research is underway to develop safeguards methods for spent fuel in centralized storage or underground storage and disposal. Each method of spent fuel storage presents different proliferation risks due to the nature of the storage method and the safeguards techniques that are utilized. Previous proliferation resistance and proliferation risk assessments have mainly compared nuclear material through the whole fuel cycle and not specifically focused on spent fuel storage. This project evaluates the proliferation resistance of the three main types of spent fuel storage: spent fuel pool, dry cask storage, and geological repository. The proliferation resistance assessment methodology that is used in this project is adopted from previous work and altered to be applicable to spent fuel storage. The assessment methodology utilizes various intrinsic and extrinsic proliferation-resistant attributes for each spent fuel storage type. These attributes are used to calculate a total proliferation resistant (PR) value. The maximum PR value is 1.00 and a greater number means that the facility is more proliferation resistant. Current data for spent fuel storage in the United States and around the world was collected. The PR values obtained from this data are 0.49 for the spent fuel pool, 0.42 for dry cask storage, 0.36 for the operating geological repository, and 0.28 for the closed geological repository. Therefore, the spent fuel pool is currently the most proliferation resistant method for storing spent fuel. The extrinsic attributes, mainly involving safeguards measures, affect the total PR value the most. As a result, several recommendations are made to improve the proliferation resistance of spent fuel. These recommendations include employing more advanced safeguards measures, such as verification techniques and remote monitoring, for dry cask storage and the geological repository. Dry cask storage facilities should also be located at the plant and in a secure building to minimize the proliferation risk. Finally, the cost-benefit analysis of increased safeguards needs to be considered. Taking these recommendations into account, the PR values of dry cask storage and the closed geological would be significantly increased, to 0.57 and 0.51, respectively. As a result, with increased safeguards to the safeguards level of the spent fuel pool, dry cask storage would be the most proliferation resistant method to store spent fuel. Therefore, the IAEA should continue to develop remote monitoring and cask storage verification techniques in order to improve the proliferation resistance of spent fuel.

Modeling and Simulation of the Gonghe geothermal field (Qinghai, China) Constrained by Geophysical

NASA Astrophysics Data System (ADS)

Zeng, Z.; Wang, K.; Zhao, X.; Huai, N.; He, R.

2017-12-01

The Gonghe geothermal field in Qinghai is important because of its variety of geothermal resource types. Now, the Gonghe geothermal field has been a demonstration area of geothermal development and utilization in China. It has been the topic of numerous geophysical investigations conducted to determine the depth to and the nature of the heat source, and to image the channel of heat flow. This work focuses on the causes of geothermal fields used numerical simulation method constrained by geophysical data. At first, by analyzing and inverting an magnetotelluric (MT) measurements profile across this area we obtain the deep resistivity distribution. Using the gravity anomaly inversion constrained by the resistivity profile, the density of the basins and the underlying rocks can be calculated. Combined with the measured parameters of rock thermal conductivity, the 2D geothermal conceptual model of Gonghe area is constructed. Then, the unstructured finite element method is used to simulate the heat conduction equation and the geothermal field. Results of this model were calibrated with temperature data for the observation well. A good match was achieved between the measured values and the model's predicted values. At last, geothermal gradient and heat flow distribution of this model are calculated(fig.1.). According to the results of geophysical exploration, there is a low resistance and low density region (d5) below the geothermal field. We recognize that this anomaly is generated by tectonic motion, and this tectonic movement creates a mantle-derived heat upstream channel. So that the anomalous basement heat flow values are higher than in other regions. The model's predicted values simulated using that boundary condition has a good match with the measured values. The simulated heat flow values show that the mantle-derived heat flow migrates through the boundary of the low-resistance low-density anomaly area to the Gonghe geothermal field, with only a small fraction moving to other regions. Therefore, the mantle-derived heat flow across the tectonic channel to the cohesive continuous supply heat for Gonghe geothermal field, is the main the main causes of abundant geothermal resources.

The realization of temperature controller for small resistance measurement system

NASA Astrophysics Data System (ADS)

Sobecki, Jakub; Walendziuk, Wojciech; Idzkowski, Adam

2017-08-01

This paper concerns the issues of construction and experimental tests of a temperature stabilization system for small resistance increments measurement circuits. After switching the system on, a PCB board heats up and the long-term temperature drift altered the measurement result. The aim of this work is reducing the time of achieving constant nominal temperature by the measurement system, which would enable decreasing the time of measurements in the steady state. Moreover, the influence of temperatures higher than the nominal on the measurement results and the obtained heating curve were tested. During the working process, the circuit heats up to about 32 °C spontaneously, and it has the time to reach steady state of about 1200 s. Implementing a USART terminal on the PC and an NI USB-6341 data acquisition card makes recording the data (concerning temperature and resistance) in the digital form and its further processing easier. It also enables changing the quantity of the regulator settings. This paper presents sample results of measurements for several temperature values and the characteristics of the temperature and resistance changes in time as well as their comparison with the output values. The object identification is accomplished due to the Ziegler-Nichols method. The algorithm of determining the step characteristics parameters and examples of computations of the regulator settings are included together with example characteristics of the object regulation.

The Challenging Diagnosis of Non-Community-Acquired Pneumonia in Non-Mechanically Ventilated Subjects: Value of Microbiological Investigation.

PubMed

Messika, Jonathan; Stoclin, Annabelle; Bouvard, Eric; Fulgencio, Jean-Pierre; Ridel, Christophe; Muresan, Ioan-Paul; Boffa, Jean-Jacques; Bachmeyer, Claude; Denis, Michel; Gounant, Valérie; Esteso, Adoracion; Loi, Valeria; Verdet, Charlotte; Prigent, Hélène; Parrot, Antoine; Fartoukh, Muriel

2016-02-01

Early recognition and an attempt at obtaining microbiological documentation are recommended in patients with non-community-acquired pneumonia (NCAP), whether hospital-acquired (HAP) or health care-associated (HCAP). We aimed to characterize the clinical features and microbial etiologies of NCAP to assess the impact of microbiological investigation on their management. This was a prospective 1-y study in a university hospital with 141 non-mechanically ventilated subjects suspected of having HAP (n = 110) or HCAP (n = 31). Clinical criteria alone poorly identified pneumonia (misdiagnosis in 50% of cases). Microbiological confirmation was achievable in 80 subjects (57%). Among 79 microorganisms isolated, 28 were multidrug-resistant aerobic Gram-negative bacilli and group III Enterobacteriaceae and 6 were methicillin-resistant Staphylococcus aureus. Multidrug-resistant aerobic Gram-negative bacilli accounted for one third of the microorganisms in early-onset HAP and for 50% in late-onset HAP. Methicillin-resistant S. aureus was most often recovered from subjects with HCAP. Inappropriate empirical antibiotics were administered to 36% of subjects with confirmed pneumonia. Forty subjects were admitted to the ICU, 13 (33%) of whom died. Overall, 39 subjects (28%) died in the hospital. Integrating the microbiological investigation in the complex clinical diagnostic workup of patients suspected of having NCAP is mandatory. Respiratory tract specimens should be obtained whenever possible for appropriate management. Copyright © 2016 by Daedalus Enterprises.

Drug Targets and Mechanisms of Resistance in the Anaerobic Protozoa

PubMed Central

Upcroft, Peter; Upcroft, Jacqueline A.

2001-01-01

The anaerobic protozoa Giardia duodenalis, Trichomonas vaginalis, and Entamoeba histolytica infect up to a billion people each year. G. duodenalis and E. histolytica are primarily pathogens of the intestinal tract, although E. histolytica can form abscesses and invade other organs, where it can be fatal if left untreated. T. vaginalis infection is a sexually transmitted infection causing vaginitis and acute inflammatory disease of the genital mucosa. T. vaginalis has also been reported in the urinary tract, fallopian tubes, and pelvis and can cause pneumonia, bronchitis, and oral lesions. Respiratory infections can be acquired perinatally. T. vaginalis infections have been associated with preterm delivery, low birth weight, and increased mortality as well as predisposing to human immunodeficiency virus infection, AIDS, and cervical cancer. All three organisms lack mitochondria and are susceptible to the nitroimidazole metronidazole because of similar low-redox-potential anaerobic metabolic pathways. Resistance to metronidazole and other drugs has been observed clinically and in the laboratory. Laboratory studies have identified the enzyme that activates metronidazole, pyruvate:ferredoxin oxidoreductase, to its nitroso form and distinct mechanisms of decreasing drug susceptibility that are induced in each organism. Although the nitroimidazoles have been the drug family of choice for treating the anaerobic protozoa, G. duodenalis is less susceptible to other antiparasitic drugs, such as furazolidone, albendazole, and quinacrine. Resistance has been demonstrated for each agent, and the mechanism of resistance has been investigated. Metronidazole resistance in T. vaginalis is well documented, and the principal mechanisms have been defined. Bypass metabolism, such as alternative oxidoreductases, have been discovered in both organisms. Aerobic versus anaerobic resistance in T. vaginalis is discussed. Mechanisms of metronidazole resistance in E. histolytica have recently been investigated using laboratory-induced resistant isolates. Instead of downregulation of the pyruvate:ferredoxin oxidoreductase and ferredoxin pathway as seen in G. duodenalis and T. vaginalis, E. histolytica induces oxidative stress mechanisms, including superoxide dismutase and peroxiredoxin. The review examines the value of investigating both clinical and laboratory-induced syngeneic drug-resistant isolates and dissection of the complementary data obtained. Comparison of resistance mechanisms in anaerobic bacteria and the parasitic protozoa is discussed as well as the value of studies of the epidemiology of resistance. PMID:11148007

Effects of organic acids on thermal inactivation of acid and cold stressed Enterococcus faecium.

PubMed

Fernández, Ana; Alvarez-Ordóñez, Avelino; López, Mercedes; Bernardo, Ana

2009-08-01

In this study the adaptative response to heat (70 degrees C) of Enterococcus faecium using fresh and refrigerated (at 4 degrees C for up to 1 month) stationary phase cells grown in Brain Heart Infusion (BHI) buffered at pH 7.4 (non-acid-adapted cells) and acidified BHI at pH values of 6.4 and 5.4 with acetic, ascorbic, citric, lactic, malic and hydrochloric acids (acid-adapted cells) was evaluated. In all cases, the survival curves obtained were concave upward. A mathematical model based on the Weibull distribution accurately described the inactivation kinetic. The results indicate that previous adaptation to a low pH increased the bacterial heat resistance, whereas the subsequent cold storage of cells reduced E. faecium thermal tolerance. Fresh acid-adapted cells showed t(2.5)-values (time needed to obtain an inactivation level of 2.5 log10 cycles) ranging from 2.57 to 9.51 min, while non-acid-adapted cells showed t(2.5)-values of 1.92 min. The extent of increased heat tolerance varied with the acid examined, resulting in the following order: citric > or = acetic > malic > or = lactic > hydrochloric > or = ascorbic. In contrast, cold storage progressively decreased E. faecium thermal resistance. The t(2.5) values found at the end of the period studied were about 2-3-fold lower than those corresponding to non-refrigerated cells, although this decrease was more marked (about 5-fold) when cells were grown in buffered BHI and BHI acidified at pH 5.4 with hydrochloric acid. These findings highlight the need for a better understanding of microbial response to various preservation stresses in order to increase the efficiency of thermal processes and to indicate the convenience of counterbalancing the benefits of the hurdle concept.

Work Function and Conductivity of Inkjet-Printed Silver Layers: Effect of Inks and Post-treatments

NASA Astrophysics Data System (ADS)

Mitra, Dana; Mitra, Kalyan Yoti; Dzhagan, Volodymyr; Pillai, Nikhil; Zahn, Dietrich R. T.; Baumann, Reinhard R.

2018-03-01

The electronic properties of a printed layer are influenced by a number of factors, including the nature of the ink (nanoparticle- or solution-based), ink composition (solvents, additives, concentration), and post-treatment technologies, especially sintering. One of the major challenges in the field of printed electronics is achieving the desired performance, for example, in terms of conductivity, resistivity, or work function (WF). This work investigates the dependence of sheet resistance and WF on various sintering methodologies. Four different silver nanoparticle inks were inkjet-printed on a flexible polymeric foil and post-treated by thermal sintering (in an oven) or novel sintering processes using infrared or intense pulsed light. The surfaces of the printed and sintered layers were investigated optically, and various inhomogeneities in the layer surface were observed, varying from a smooth to a highly rough appearance with ring-shaped drying structures. An analysis of the sheet resistance revealed notable variation among the various inks and sintering methodologies used. Here, for the very first time, WF is measured and evaluated as a function of sintering methodology and silver ink, and the respective layer formation characteristics realized with the inkjet printing technology. The WF values obtained by ultraviolet photoemission show a similar spread and allow unambiguous trends to be tracked with respect to the type of ink and sintering method used. The values of the WF obtained range from 3.7 eV to 4.3 eV, approaching the reported bulk values of 4.3-4.7 eV. The various silver inks resulted in different WFs when the same sintering method was used, while the same silver ink resulted in different WFs when various sintering methods were applied. Therefore, it is believed that the WF can be tuned over a broad range in a controlled manner to satisfy electronic device requirements.

Pulmonary vascular input impedance is a combined measure of pulmonary vascular resistance and stiffness and predicts clinical outcomes better than pulmonary vascular resistance alone in pediatric patients with pulmonary hypertension.

PubMed

Hunter, Kendall S; Lee, Po-Feng; Lanning, Craig J; Ivy, D Dunbar; Kirby, K Scott; Claussen, Lori R; Chan, K Chen; Shandas, Robin

2008-01-01

Pulmonary vascular resistance (PVR) is the current standard for evaluating reactivity in children with pulmonary arterial hypertension (PAH). However, PVR measures only the mean component of right ventricular afterload and neglects pulsatile effects. We recently developed and validated a method to measure pulmonary vascular input impedance, which revealed excellent correlation between the zero harmonic impedance value and PVR and suggested a correlation between higher-harmonic impedance values and pulmonary vascular stiffness. Here we show that input impedance can be measured routinely and easily in the catheterization laboratory, that impedance provides PVR and pulmonary vascular stiffness from a single measurement, and that impedance is a better predictor of disease outcomes compared with PVR. Pressure and velocity waveforms within the main pulmonary artery were measured during right heart catheterization of patients with normal pulmonary artery hemodynamics (n = 14) and those with PAH undergoing reactivity evaluation (49 subjects, 95 conditions). A correction factor needed to transform velocity into flow was obtained by calibrating against cardiac output. Input impedance was obtained off-line by dividing Fourier-transformed pressure and flow waveforms. Exceptional correlation was found between the indexed zero harmonic of impedance and indexed PVR (y = 1.095x + 1.381, R2 = 0.9620). In addition, the modulus sum of the first 2 harmonics of impedance was found to best correlate with indexed pulse pressure over stroke volume (y = 13.39x - 0.8058, R2 = 0.7962). Among a subset of patients with PAH (n = 25), cumulative logistic regression between outcomes to total indexed impedance was better (R(L)2 = 0.4012) than between outcomes and indexed PVR (R(L)2 = 0.3131). Input impedance can be consistently and easily obtained from pulse-wave Doppler and a single catheter pressure measurement, provides comprehensive characterization of the main components of RV afterload, and better predicts patient outcomes compared with PVR alone.

Motion resistant pulse oximetry in neonates

PubMed Central

Sahni, R; Gupta, A; Ohira-Kist, K; Rosen, T

2003-01-01

Background: Pulse oximetry is widely used in neonates. However, its reliability is often affected by motion artefact. Clinicians confronted with questionable oxygen saturation (SpO2) values often estimate the reliability by correlating heart rate (HR) obtained with the oximeter with that obtained by electrocardiogram. Objective: To compare the effects of motion on SpO2 and HR measurements made with Masimo signal extraction technology and those made with a Nellcor N-200. Design: Continuous pulse oximetry and HR monitoring were performed in 15 healthy, term infants (mean (SD) birth weight 3408 (458) g) undergoing circumcision, using Masimo and Nellcor pulse oximeters and a standard HR monitor (Hewlett-Packard). Simultaneous minute by minute behavioural activity codes were also assigned. Baseline data were collected for 10 minutes when the infant was quietly asleep and then continued during and after circumcision for a total duration of one hour. The oximeter HR and SpO2 values were compared and related to HR values obtained by ECG during all three periods. The effect of behavioural activity on SpO2 and HR was also evaluated. Results: When compared with results obtained with the Nellcor, the mean SpO2 and HR were higher and the incidence of artefact lower with the Masimo during all three periods. Masimo HR more accurately predicted HR obtained with a standard monitor, with lower residual error. SpO2 and HR values obtained with the Nellcor were lower and more variable during all behavioural states, especially crying, when excessive motion artefact was most likely. Conclusions: The data suggest that Masimo signal extraction technology may offer improvement in pulse oximetry performance, particularly in clinical situations in which extreme motion artefacts are likely. PMID:14602699

Prevalence of multidrug-resistant, coagulase-positive Staphylococcus aureus in nasal carriage, food, wastewater and paper currency in Jalandhar city (north-western), an Indian state of Punjab.

PubMed

Kumar, Harsh; Palaha, Rajdeep; Kaur, Navreet; Ratnakar, Wankhede Swapnil; Sodi, Aakanksha; Kaur, Manmeet; Katiyar, Richa; Sharma, Mamta; Kaur, Charanpreet; Kumar, Virendra

2015-01-01

Development of multidrug-resistant pattern in the bacterial community is a major threat to the society. Staphylococcus aureus is perhaps the pathogen of the greatest concern because of its inherent virulence, its ability to cause a diverse array of life-threatening situations and capacity to adapt to different environmental conditions. The aims of this study is to investigate the multidrug-resistant pattern of the coagulase-positive S. aureus isolated from nasal carriage, food, paper currency and wastewater samples. We had also studied the multiple antibiotic resistance index and in vitro production of β-lactamase. The study had found out 130 coagulase-positive S. aureus strains isolated from total of 595 samples such as anterior nares of preschool children (195), hospital nurses (100), drivers (76), food (86), wastewater (3) and paper currency (135) (Indian rupee). The biotypes pattern were as follows; A > D > B > C> UT. Multiple antibiotic resistance (MAR) value clearly defines the multidrug-resistant pattern of the S. aureus among different sources. Statistical analysis (one-way ANOVA) of results obtained indicated that the difference in the antibiotic resistance observed in the 130 bacterial isolates against the 23 different antibiotics used in this study was statically significant (p < 0.01).

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

Luo, P.F.; Wang, J.S.; Chao, Y.J.

The stereo vision is used to study the fracture behavior in the compact tension (CT) specimen made from 304L stainless steel. During crack tip blunting, initiation, and growth in the CT specimen, both in-plane and out-of-plane displacement fields near the crack tip are measured by the stereo vision. Based on the plane stress assumption and the deformation theory of plasticity, the J integral is evaluated along several rectangular paths surrounding the crack tip by using the measured in-plane displacement field. Prior to crack growth, the J integral is path independent. For crack extension up to {Delta}a {approx} 3 mm, themore » near field J integral values are 6% to 10% lower than far field J integral values. For the crack extension of {Delta}a {approx} 4 mm, the J integral lost path independence. The far field J integral values are in good agreement with results obtained from Merkle-Corten`s formula. Both J-{Delta}a and CTOA-{Delta}a are obtained by computing the J integral value and crack tip opening angle (CTOA) at each {Delta}a. Results indicate that CTOA reached a nearly constant value at a crack extension of {Delta}a = 3 mm with a leveled resistance curve thereafter. Also, the J integral value is determined by the maximum transverse diameter of the shadow spots, which are generated by using the out-of-plane displacement field. Results indicate that for crack extension up to 0.25 mm, the J integral values evaluated by using the out-of- plane displacement are close to those obtained by using in-plane displacements and Merkle-Corten`s formula.« less

Traction test of temporary dental cements.

PubMed

Román-Rodríguez, Juan-Luis; Millan-Martínez, Diego; Fons-Font, Antonio; Agustín-Panadero, Rubén; Fernández-Estevan, Lucía

2017-04-01

Classic self-curing temporary cements obstruct the translucence of provisional restorations. New dual-cure esthetic temporary cements need investigation and comparison with classic cements to ensure that they are equally retentive and provide adequate translucence. The objective is to analyze by means of traction testing in a in vitro study the retention of five temporary cements. Ten molars were prepared and ten provisional resin restorations were fabricated using CAD-CAM technology (n=10). Five temporary cements were selected: self-curing temporary cements, Dycal (D), Temp Bond (TB), Temp Bond Non Eugenol (TBNE); dual-curing esthetic cements Temp Bond Clear (TBC) and Telio CS link (TE). Each sample underwent traction testing, both with thermocycling (190 cycles at 5-55º) and without thermocycling. TE and TBC obtained the highest traction resistance values. Thermocycling reduced the resistance of all cements except TBC. The dual-cure esthetic cements tested provided optimum outcomes for bonding provisional restorations. Key words: Temporary dental cements, cements resistance.

Molecular resistance mechanisms of Mycoplasma agalactiae to macrolides and lincomycin.

PubMed

Prats-van der Ham, Miranda; Tatay-Dualde, Juan; de la Fe, Christian; Paterna, Ana; Sánchez, Antonio; Corrales, Juan Carlos; Contreras, Antonio; Gómez-Martín, Ángel

2017-11-01

The extensive use of antimicrobials for disease control has caused a remarkable decrease in antimicrobial susceptibility of different animal mycoplasma species, including Mycoplasma agalactiae (M. agalactiae), the main causative agent of contagious agalactia. However, the molecular mechanisms behind M. agalactiae resistance to macrolides and lincomycin have not yet been elucidated. The aim of the present study was to investigate the association between minimum inhibitory concentration (MIC) values of different antimicrobials and mutations in the 23S rRNA gene and ribosomal proteins L4 and L22, analysing both field isolates (n=50) and in vitro selected resistant mutants of M. agalactiae. The obtained MIC results of the studied field isolates demonstrate an increasing development of tylosin resistance in this bacterium, in comparison to previous studies. Interestingly, predicted amino acid changes in L22 (Ser89Leu and Gln90Lys/His) were the first variations observed when MICs of M. agalactiae started to increase (tylosin MIC ≥0.8μg/ml), whereas mutations at positions 2058 or 2059 of domain V of the 23S rRNA gene appeared from MIC values of 1.6μg/ml. These results were consistent in both field isolates and in vitro selected mutants of M. agalactiae. Thus, although in other mycoplasma species resistance to macrolides and lincosamides had been mainly related to mutations in the 23S rRNA gene, this work demonstrates the role of alterations in ribosomal protein L22 in decreased susceptibility of M. agalactiae. Moreover, these mutations can be used as molecular markers to set an interpretative breakpoint of antimicrobial resistance for M. agalactiae. Copyright © 2017 Elsevier B.V. All rights reserved.

Antimicrobial susceptibility and genetic relatedness of respiratory tract pathogens in weaner pigs over a 12-month period.

PubMed

Niemann, Lisa; Müller, Petra; Brauns, Jasmin; Nathaus, Rolf; Schäkel, Franziska; Kipschull, Kerstin; Höltig, Doris; Wendt, Michael; Schwarz, Stefan; Kadlec, Kristina

2018-06-01

The collaboration project VASIB aims at reducing the antibiotic consumption in pig production by integrating information from consulting expertise in clinical inspection, hygiene, epidemiology, microbiology and pharmacology. In this VASIB subproject, we investigated the antimicrobial susceptibility and relatedness of porcine respiratory tract pathogens. Bordetella bronchiseptica (n = 47), Pasteurella multocida (n = 18) and Streptococcus suis (n = 58) were obtained from weaner pigs at two farms. Antimicrobial susceptibility testing was performed by broth microdilution according to CLSI standards. Resistance genes were detected via specific PCR assays. Macrorestriction analysis was conducted to determine the relatedness of the isolates and to identify clones. The B. bronchiseptica isolates showed indistinguishable (farm 1) or two closely related XbaI-patterns (farm 2). Different SmaI-PFGE patterns of P. multocida isolates were obtained at three different time points. In contrast, PFGE analysis of S. suis indicated more than one fragment pattern per pig and time point. Isolates exhibiting indistinguishable PFGE patterns were considered to represent the same clone. This study showed that only two closely related B. bronchiseptica clones were present in both farms, which had low MICs to all antimicrobials, except to β-lactams. Different P. multocida clones were present at the three time points. They showed overall low MIC values, with two clones being resistant and one intermediate to tetracycline. S. suis clones were resistant to tetracycline (n = 19) and/or erythromycin/clindamycin (n = 16). They harboured the tetracycline resistance genes tet(O), tet(M) or tet(L) and/or the macrolide/lincosamide/streptogramin B resistance gene erm(B). Five penicillin-resistant S. suis clones were also detected. Copyright © 2018 Elsevier B.V. All rights reserved.

Kinetics of Hypotension during 50 Sessions of Resistance and Aerobic Training in Hypertensive Patients: a Randomized Clinical Trial

PubMed Central

Damorim, Igor Rodrigues; Santos, Tony Meireles; Barros, Gustavo Willames Pimentel; Carvalho, Paulo Roberto Cavalcanti

2017-01-01

Background Resistance and aerobic training are recommended as an adjunctive treatment for hypertension. However, the number of sessions required until the hypotensive effect of the exercise has stabilized has not been clearly established. Objective To establish the adaptive kinetics of the blood pressure (BP) responses as a function of time and type of training in hypertensive patients. Methods We recruited 69 patients with a mean age of 63.4 ± 2.1 years, randomized into one group of resistance training (n = 32) and another of aerobic training (n = 32). Anthropometric measurements were obtained, and one repetition maximum (1RM) testing was performed. BP was measured before each training session with a digital BP arm monitor. The 50 training sessions were categorized into quintiles. To compare the effect of BP reduction with both training methods, we used two-way analysis of covariance (ANCOVA) adjusted for the BP values obtained before the interventions. The differences between the moments were established by one-way analysis of variance (ANOVA). Results The reductions in systolic (SBP) and diastolic BP (DBP) were 6.9 mmHg and 5.3 mmHg, respectively, with resistance training and 16.5 mmHg and 11.6 mmHg, respectively, with aerobic training. The kinetics of the hypotensive response of the SBP showed significant reductions until the 20th session in both groups. Stabilization of the DBP occurred in the 20th session of resistance training and in the 10th session of aerobic training. Conclusion A total of 20 sessions of resistance or aerobic training are required to achieve the maximum benefits of BP reduction. The methods investigated yielded distinct adaptive kinetic patterns along the 50 sessions. PMID:28380132

Comparison of frictional resistance among conventional, active and passive selfligating brackets with different combinations of arch wires: a finite elements study.

PubMed

Gómez, Sandra L; Montoya, Yesid; Garcia, Nora L; Virgen, Ana L; Botero, Javier E

2016-09-01

The aim of this study was to compare frictional resistance among conventional, passive and active selfligating brackets using Finite Elements Analysis (FEA). Seventynine (79) slide tests were performed by combining an upper first bicuspid conventional bracket, 0.018" stainless steel wires and 0.010" ligature by means of an INSTRON 3345 load system to obtain average maximum static frictional resistance (MSFR). This value was compared to the FR (frictional resistance) obtained by simulation of a slide of the same combination by FEA following conventional bracket modeling by means of Computer Aided Design (CAD). Once the FEA was validated, bracket CADs were designed (upper right first bicuspid conventional, active and passive selfligating bracket) and bracket properties calculated. MSFR was compared among conventional, active and passive selfligating brackets with different alloys and archwire cross sections such as 0.018", 0.019" x 0.025"and 0.020" x 0.020". Passive selfligating brackets had the lowest MSFR, followed by conventional brackets and active selfligating brackets. In conventional brackets, a 0.018" archwire produced a linear pattern of stress with maximum concentration at the center. Conversely, stress in 0.020 x 0.020" and 0.019 x 0.025" archwires was distributed across the width of the slot. The highest normal forces were 1.53 N for the 0.018" archwire, 4.85 N for the 0.020 x 0.020" archwire and 8.18 N for the 0.019 x 0.025" archwire. Passive selfligating brackets presented less frictional resistance than conventional and active selfligating brackets. Regardless of bracket type, greater contact area between the slot and the archwire and the spring clip increased frictional resistance. Sociedad Argentina de Pediatría.

Phenotypical and Genotypical Antimicrobial Resistance of Coagulase-negative staphylococci Isolated from Cow Mastitis.

PubMed

Klimiene, I; Virgailis, M; Pavilonis, A; Siugzdiniene, R; Mockeliunas, R; Ruzauskas, M

2016-09-01

The objectives of this study were to determine the prevalence and antimicrobial resistance of coagulase-negative staphylococci (CNS) isolated from dairy cows with subclinical mastitis. Antimicrobial resistance in staphylococci were evaluated by breakpoint values specific to the species (EU-CAST). The presence of resistance-encoding genes was detected by multiplex PCR. A total of 191 CNS isolates were obtained. The CNS isolates were typically resistant to penicillin (67.4%), tetracyc-line (18.9%), and erythromycin (13.7%). CNS isolates (78.0%) were resistant to at least one antimicrobial compound, and 22.0% were multiresistant. The multiresistant isolates were predominantly Staphylococcus chromogenes (28.6%), Staphylococcus warneri (19%) and Staphylococcus haemolyticus (14.3%). According to MIC pattern data, multiresistant isolates showed the highest resistance (p<0.05) rates to penicillin (85.7%), tetracycline (66.7%), and erythromycin (48.2%), but all of them were sensitive to daptomycin, oxacillin, qiunupristin/dalfopristin, and vancomycin. S. chromogenes (9.5%), S. haemolyticus (4.8%), and S. capitis ss capitis (2.4%) strains were resistant to methicillin; their resistance to oxacillin and penicillin was more than 8 mg/l. A high rate of resistance to penicillin was linked to a blaZ gene found in 66.6% of the isolated multiresistant CNS strains. Resistance to tetracycline via the tetK (38.1%) gene and penicillin via the mecA (23.8%) gene were detected less frequently. Gene msrAB was responsible for macrolides and lincosamides resistance and detected in 28.6% of the CNS isolates. Antimicrobial resistance genes were identified more frequently in S. epidermidis, S. chromogenes, and S. warneri.

Phosphorene/rhenium disulfide heterojunction-based negative differential resistance device for multi-valued logic

NASA Astrophysics Data System (ADS)

Shim, Jaewoo; Oh, Seyong; Kang, Dong-Ho; Jo, Seo-Hyeon; Ali, Muhammad Hasnain; Choi, Woo-Young; Heo, Keun; Jeon, Jaeho; Lee, Sungjoo; Kim, Minwoo; Song, Young Jae; Park, Jin-Hong

2016-11-01

Recently, negative differential resistance devices have attracted considerable attention due to their folded current-voltage characteristic, which presents multiple threshold voltage values. Because of this remarkable property, studies associated with the negative differential resistance devices have been explored for realizing multi-valued logic applications. Here we demonstrate a negative differential resistance device based on a phosphorene/rhenium disulfide (BP/ReS2) heterojunction that is formed by type-III broken-gap band alignment, showing high peak-to-valley current ratio values of 4.2 and 6.9 at room temperature and 180 K, respectively. Also, the carrier transport mechanism of the BP/ReS2 negative differential resistance device is investigated in detail by analysing the tunnelling and diffusion currents at various temperatures with the proposed analytic negative differential resistance device model. Finally, we demonstrate a ternary inverter as a multi-valued logic application. This study of a two-dimensional material heterojunction is a step forward toward future multi-valued logic device research.

Phosphorene/rhenium disulfide heterojunction-based negative differential resistance device for multi-valued logic

PubMed Central

Shim, Jaewoo; Oh, Seyong; Kang, Dong-Ho; Jo, Seo-Hyeon; Ali, Muhammad Hasnain; Choi, Woo-Young; Heo, Keun; Jeon, Jaeho; Lee, Sungjoo; Kim, Minwoo; Song, Young Jae; Park, Jin-Hong

2016-01-01

Recently, negative differential resistance devices have attracted considerable attention due to their folded current–voltage characteristic, which presents multiple threshold voltage values. Because of this remarkable property, studies associated with the negative differential resistance devices have been explored for realizing multi-valued logic applications. Here we demonstrate a negative differential resistance device based on a phosphorene/rhenium disulfide (BP/ReS2) heterojunction that is formed by type-III broken-gap band alignment, showing high peak-to-valley current ratio values of 4.2 and 6.9 at room temperature and 180 K, respectively. Also, the carrier transport mechanism of the BP/ReS2 negative differential resistance device is investigated in detail by analysing the tunnelling and diffusion currents at various temperatures with the proposed analytic negative differential resistance device model. Finally, we demonstrate a ternary inverter as a multi-valued logic application. This study of a two-dimensional material heterojunction is a step forward toward future multi-valued logic device research. PMID:27819264

A 3D joint interpretation of magnetotelluric and seismic tomographic models: The case of the volcanic island of Tenerife

NASA Astrophysics Data System (ADS)

García-Yeguas, Araceli; Ledo, Juanjo; Piña-Varas, Perla; Prudencio, Janire; Queralt, Pilar; Marcuello, Alex; Ibañez, Jesús M.; Benjumea, Beatriz; Sánchez-Alzola, Alberto; Pérez, Nemesio

2017-12-01

In this work we have done a 3D joint interpretation of magnetotelluric and seismic tomography models. Previously we have described different techniques to infer the inner structure of the Earth. We have focused on volcanic regions, specifically on Tenerife Island volcano (Canary Islands, Spain). In this area, magnetotelluric and seismic tomography studies have been done separately. The novelty of the present work is the combination of both techniques in Tenerife Island. For this aim we have applied Fuzzy Clusters Method at different depths obtaining several clusters or classes. From the results, a geothermal system has been inferred below Teide volcano, in the center of Tenerife Island. An edifice hydrothermally altered and full of fluids is situated below Teide, ending at 600 m below sea level. From this depth the resistivity and VP values increase downwards. We also observe a clay cap structure, a typical feature in geothermal systems related with low resistivity and low VP values.

Study of the Effects of High Temperatures on the Engineering Properties of Steel 42CrMo4

NASA Astrophysics Data System (ADS)

Brnic, Josip; Turkalj, Goran; Canadija, Marko; Lanc, Domagoj; Brcic, Marino

2015-02-01

The paper presents and analyzes the experimental results of the effect of elevated temperatures on the engineering properties of steel 42CrMo4. Experimental data relating to the mechanical properties of the material, the creep resistance as well as Charpy impact energy. Temperature dependence of the mentioned properties is also shown. Some of creep curves were simulated using rheological models and an analytical equation. Finally, an assessment of fracture toughness was made that was based on experimentally determined Charpy impact energy. Based on the obtained results it is visible that the tensile strength (617 MPa) and yield strength (415 MPa) have the highest value at the room temperature while at the temperature of 700 °C (973 K) these values significantly decrease. This steel can be considered resistant to creep at 400 °C (673 K), but at higher temperatures this steel can be subjected to low levels of stress in a shorter time.

The Discontinuity in the First Derivative of the ITS-90 at the Triple Point of Water

NASA Astrophysics Data System (ADS)

Rusby, R. L.

2010-09-01

This paper investigates the discontinuity in the derivative [d W/d T 90]TPW of the ITS-90 at the triple point of water, using data for over 40 calibrated standard platinum resistance thermometers (SPRTs). It finds that the discontinuity is in most cases somewhere between 0 and -6 parts in 105, in relative terms, but that the higher numerical values are obtained for `less ideal' SPRTs (those with lower temperature coefficients of resistance), and also for sub-ranges not extending beyond the indium point. These results are investigated vis-à-vis the long-standing observation that the ITS-90 reference values W r(Ga) and W r(Hg) are not completely consistent with data for W(Ga) and W(Hg) for real SPRTs. It discusses what may be done in a future scale to ensure continuity in the first derivative, and it concludes with a comment about the acceptance criteria for SPRTs in the scale.

Valuing goat genetic resources: a pro-poor growth strategy in the Kenyan semi-arid tropics.

PubMed

Omondi, I A; Baltenweck, I; Drucker, A G; Obare, G A; Zander, K K

2008-12-01

Goats, "the poor man's cow", provide very important genetic resources that can be exploited for continued improvements of the livelihoods of poor livestock keepers in the semi-arid tropics. This study presents the evaluation of the economic values of goat genetic resources (GGRs) in terms of the important non-market traits embedded in goats and how this information can be utilised to improve livelihoods in semi-arid regions. The results obtained from mixed logit models derived from stated choice data collected from 314 respondents in the semi-arid Marsabit district of Kenya reveal that disease resistance is the most highly valued trait whose resultant augmentation results into a welfare improvement of up to KShs.2899. Drought tolerance and milk traits were found to be implicitly valued at KShs.2620 and 1179 respectively. The study further revealed that improvement in milk trait in does, body size and disease resistance traits in bucks, and drought tolerance trait in both does and bucks will collectively improve the producers' welfare hence should be given priority. However, improvement in the reproduction and production ("overall body condition/ meatiness" trait) potential of goats will be worthwhile only if issues concerning access to pasture and water resources are addressed prior and simultaneously.

Electroless plating Cu-Co-P polyalloy on UV/ozonolysis irradiated polyethylene terephthalate film and its corrosion resistance

NASA Astrophysics Data System (ADS)

Hou, Lei; Bi, Siyi; Zhao, Hang; Xu, Yumeng; Mu, Yuhang; Lu, Yinxiang

2017-05-01

High corrosion resistant Cu-Co-P coatings were firstly prepared on polyethylene terephthalate (PET) substrate by electroless plating in combination with UV/ozonolysis irradiation under optimized cobalt sulfate heptahydrate concentration, pH value, plating temperature and time. The copper polyalloy/PET composite can be obtained in three steps, namely: (i) the generation of oxygen-containing functionalities (carboxylic groups) onto PET surface through UV irradiation combined with ozone, (ii) Cu seeding catalysts were obtained after being immersed into cupric citrate and NaBH4 solutions subsequently, and (iii) Cu-Co-P polyalloy metallization using electroless plating bath. Attenuated total reflection fourier transformation infrared spectrometer (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), water contact angle measurement and energy dispersive X-ray analysis (EDAX) were utilized to track the surface changes during the whole process. The electroless plating conditions were optimized by an orthogonal experiment (L9(3)4) for Cu-Co-P coating as follows: CoSO4·7H2O addition of 0.08 M, pH value, plating temperature and time were set on 10.0, 35 °C and 25 min, respectively. Under the optimal conditions, copper polyalloy possessed high adhesive strength and the lowest surface resistance (8.06 Ω/sq), while maintaining reliability even after over 1000 times of bending and mechanical stress. The results of scanning electron microscope (SEM) and atomic force microscope (AFM) measurements showed that Cu-Co-P layer formed on PET surface was imparted with fine uniformity and high compactness. Electrochemical test revealed the optimized Cu-Co-P coatings exhibited high corrosion resistance in NaCl, NaOH and HCl solutions, respectively. The excellent electromagnetic interference shielding effectiveness (EMI SE >99.999% at frequency ranging from 30 MHz to 1000 MHz) of copper polyalloy/PET composites was confirmed by the spectrum analyzer. Therefore, this copper polyalloy will have potential applications in microelectronics packaging and coatings for anti-corrosion and electromagnetic interference shielding.

Understanding the effects of cationic dopants on α-MnO 2 oxygen reduction reaction electrocatalysis

DOE PAGES

Lambert, Timothy N.; Vigil, Julian A.; White, Suzanne E.; ...

2017-01-09

Nickel-doped α-MnO 2 nanowires (Ni–α-MnO 2) were prepared with 3.4% or 4.9% Ni using a hydrothermal method. A comparison of the electrocatalytic data for the oxygen reduction reaction (ORR) in alkaline electrolyte versus that obtained with α-MnO 2 or Cu–α-MnO 2 is provided. In general, Ni-α-MnO 2 (e.g., Ni-4.9%) had higher n values (n = 3.6), faster kinetics (k = 0.015 cm s –1), and lower charge transfer resistance (R CT = 2264 Ω at half-wave) values than MnO 2 (n = 3.0, k = 0.006 cm s –1, R CT = 6104 Ω at half-wave) or Cu–α-MnO 2 (Cu-2.9%,more » n = 3.5, k = 0.015 cm s –1, R CT = 3412 Ω at half-wave), and the overall activity for Ni–α-MnO 2 trended with increasing Ni content, i.e., Ni-4.9% > Ni-3.4%. As observed for Cu–α-MnO 2, the increase in ORR activity correlates with the amount of Mn 3+ at the surface of the Ni–α-MnO 2 nanowire. Examining the activity for both Ni–α-MnO 2 and Cu–α-MnO 2 materials indicates that the Mn 3+ at the surface of the electrocatalysts dictates the activity trends within the overall series. Single nanowire resistance measurements conducted on 47 nanowire devices (15 of α-MnO 2, 16 of Cu–α-MnO 2-2.9%, and 16 of Ni–α-MnO 2-4.9%) demonstrated that Cu-doping leads to a slightly lower resistance value than Ni-doping, although both were considerably improved relative to the undoped α-MnO 2. As a result, the data also suggest that the ORR charge transfer resistance value, as determined by electrochemical impedance spectroscopy, is a better indicator of the cation-doping effect on ORR catalysis than the electrical resistance of the nanowire.« less

A SYBR Green 1-based in vitro test of susceptibility of Ghanaian Plasmodium falciparum clinical isolates to a panel of anti-malarial drugs.

PubMed

Quashie, Neils B; Duah, Nancy O; Abuaku, Benjamin; Quaye, Lydia; Ayanful-Torgby, Ruth; Akwoviah, George A; Kweku, Margaret; Johnson, Jacob D; Lucchi, Naomi W; Udhayakumar, Venkatachalam; Duplessis, Christopher; Kronmann, Karl C; Koram, Kwadwo A

2013-12-17

Based on report of declining efficacy of chloroquine, Ghana shifted to the use of artemisinin-based combination therapy (ACT) in 2005 as the first-line anti-malarial drug. Since then, there has not been any major evaluation of the efficacy of anti-malarial drugs in Ghana in vitro. The sensitivity of Ghanaian Plasmodium falciparum isolates to anti-malarial drugs was, therefore, assessed and the data compared with that obtained prior to the change in the malaria treatment policy. A SYBR Green 1 fluorescent-based in vitro drug sensitivity assay was used to assess the susceptibility of clinical isolates of P. falciparum to a panel of 12 anti-malarial drugs in three distinct eco-epidemiological zones in Ghana. The isolates were obtained from children visiting health facilities in sentinel sites located in Hohoe, Navrongo and Cape Coast municipalities. The concentration of anti-malarial drug inhibiting parasite growth by 50% (IC50) for each drug was estimated using the online program, ICEstimator. Pooled results from all the sentinel sites indicated geometric mean IC50 values of 1.60, 3.80, 4.00, 4.56, 5.20, 6.11, 10.12, 28.32, 31.56, 93.60, 107.20, and 8952.50 nM for atovaquone, artesunate, dihydroartemisin, artemether, lumefantrine, amodiaquine, mefloquine, piperaquine, chloroquine, tafenoquine, quinine, and doxycycline, respectively. With reference to the literature threshold value indicative of resistance, the parasites showed resistance to all the test drugs except the artemisinin derivatives, atovaquone and to a lesser extent, lumefantrine. There was nearly a two-fold decrease in the IC50 value determined for chloroquine in this study compared to that determined in 2004 (57.56 nM). This observation is important, since it suggests a significant improvement in the efficacy of chloroquine, probably as a direct consequence of reduced drug pressure after cessation of its use. Compared to that measured prior to the change in treatment policy, significant elevation of artesunate IC50 value was observed. The results also suggest the existence of possible cross-resistance among some of the test drugs. Ghanaian P. falciparum isolates, to some extent, have become susceptible to chloroquine in vitro, however the increasing trend in artesunate IC50 value observed should be of concern. Continuous monitoring of ACT in Ghana is recommended.

Topological Defects in Double Exchange Materials and Anomalous Hall Resistance.

NASA Astrophysics Data System (ADS)

Calderón, M. J.; Brey, L.

2000-03-01

Recently it has been proposed that the anomalous Hall effect observed in Double Exchange materials is due to Berry phase effects caused by carrier hopping in a nontrivial spins background (J.Ye et al.) Phys.Rev.Lett. 83, 3737 1999.In order to study this possibility we have performed Monte Carlo simulations of the Double Exchange model and we have computed, as a function of the temperature, the number of topological defects in the system and the internal gauge magnetic field associated with these defects. In the simplest Double Exchange model the gauge magnetic field is random, and its average value is zero. The inclusion in the problem of spin-orbit coupling privileges the opposite direction of the magnetization and an anomalous Hall resistance (AHR) effect arises. We have computed the AHR, and we have obtained its temperature dependence. In agreement with previous experiments we obtain that AHR increases exponentially at low temperature and presents a maximum at a temperature slightly higher than the critical temperature.

Using open hole and cased-hole resistivity logs to monitor gas hydrate dissociation during a thermal test in the mallik 5L-38 research well, Mackenzie Delta, Canada

USGS Publications Warehouse

Anderson, B.I.; Collett, T.S.; Lewis, R.E.; Dubourg, I.

2008-01-01

Gas hydrates, which are naturally occurring ice-like combinations of gas and water, have the potential to provide vast amounts of natural gas from the world's oceans and polar regions. However, producing gas economically from hydrates entails major technical challenges. Proposed recovery methods such as dissociating or melting gas hydrates by heating or depressurization are currently being tested. One such test was conducted in northern Canada by the partners in the Mallik 2002 Gas Hydrate Production Research Well Program. This paper describes how resistivity logs were used to determine the size of the annular region of gas hydrate dissociation that occurred around the wellbore during the thermal test in the Mallik 5L-38 well. An open-hole logging suite, run prior to the thermal test, included array induction, array laterolog, nuclear magnetic resonance and 1.1-GHz electromagnetic propagation logs. The reservoir saturation tool was run both before and after the thermal test to monitor formation changes. A cased-hole formation resistivity log was run after the test.Baseline resistivity values in each formation layer (Rt) were established from the deep laterolog data. The resistivity in the region of gas hydrate dissociation near the wellbore (Rxo) was determined from electromagnetic propagation and reservoir saturation tool measurements. The radius of hydrate dissociation as a function of depth was then determined by means of iterative forward modeling of cased-hole formation resistivity tool response. The solution was obtained by varying the modeled dissociation radius until the modeled log overlaid the field log. Pretest gas hydrate production computer simulations had predicted that dissociation would take place at a uniform radius over the 13-ft test interval. However, the post-test resistivity modeling showed that this was not the case. The resistivity-derived dissociation radius was greatest near the outlet of the pipe that circulated hot water in the wellbore, where the highest temperatures were recorded. The radius was smallest near the center of the test interval, where a conglomerate section with low values of porosity and permeability inhibited dissociation. The free gas volume calculated from the resistivity-derived dissociation radii yielded a value within 20 per cent of surface gauge measurements. These results show that the inversion of resistivity measurements holds promise for use in future gas hydrate monitoring. ?? 2008 Society of Petrophysicists and Well Log Analysts. All rights reserved.

Instrumentation, methods, and preliminary evaluation of evapotranspiration for a grassland in the Arid Lands Ecology Reserve, Benton County, Washington, May-October 1990

USGS Publications Warehouse

Tomlinson, S.A.

1994-01-01

The report describes instrumentation, methods, and preliminary results for a study on evapo- transpiration at a grassland in Snively Basin of the Arid Lands Ecology Reserve. Instrumentation was used to collect data from May 30 to October 15, 1990. A combination of the Bowen-ratio and Penman-Monteith methods was used to calculate estimates of evapotranspiration. The Bowen-ratio method could be used to calculate estimates of latent-heat flux and evapotranspiration during only parts of the study period. Latent-heat flux values obtained during these periods were used in the Penman-Monteith method to estimate the canopy resistance. These canopy resistances were averaged for each day and the average values were used to recalculate the laten-heat flux for all periods using the Penman-Monteith method. The canopy resistance ranged from near zero during periods of rainfall to more than 40,000 seconds per meter during periods of extreme dryness. Evapotranspiration estimates varied during the study period. Daily evapotranspiration ranged from less than 0.1 millimeter on some days in August, September, and October to about 2 milli- meters on June 3 and August 22. Monthly totals of evapotranspiration were as follows: June, 28.2 millimeters; July, 10.5 millimeters; August, 15.0 millimeters; September, 5.3 millimeters; and October 1-15, 1.8 millimeters. Evapotranspiration values given in the report are estimates. Some error, perhaps as low as 25 percent on a daily basis and 4 percent on a monthly total basis, is probably introduced into these estimates through complexities of data collection, data analysis, and canopy-resistance estimation, particularly when evapotranspiration was near zero.

Effect of growth temperature on the electronic transport and anomalous Hall effect response in co-sputtered Co2FeSi thin films

NASA Astrophysics Data System (ADS)

Yadav, Anjali; Chaudhary, Sujeet

2015-11-01

Co-sputtered Co2FeSi thin films are studied by varying the growth temperature (Ts) as a control parameter in terms of the appreciable change in the disorder. The effect of Ts on structural, magnetic, electrical, and magneto-transport properties was investigated. As Ts is increased from room temperature to 400 °C, an improvement in the crystallinity and atomic ordering are observed. These are found to be correlated with the associated reduction in residual resistivity ( ρ x x 0 ) from 410 to 88 μΩ cm, an increment in residual resistivity ratio (r) from 0.8 to 1.23, and an increase in saturation magnetization from 1074 to 1196 emu/cc. The spin wave stiffness constant in these films is found to increase with Ts, with a reasonably high value of 358 meVÅ2 at the optimum value of Ts of 400 °C. Further, the obtained high carrier concentration and mobility values (at 10 K) of ˜30 e-s/f.u. and ˜0.11 cm2 V-1 s-1 for the films deposited at Ts = 400 °C shows the presence of compensated Fermi surface. The transport properties are investigated qualitatively from the scaling of anomalous Hall resistivity ρx y s (T) with the longitudinal resistivity ρ x x ( T ) data, employing the extrinsic (skew- and side-jump scatterings) and intrinsic scattering contributions. The variation in the intrinsic scattering contributions observed via the variation in linear dependence of ρx y s on ρx x 2 with the change in Ts is found to be associated with the improvement in the crystallinity of these films.

Antimicrobial Susceptibility of Udder Pathogens Isolated from Dairy Herds in the West Littoral Region of Uruguay

PubMed Central

2002-01-01

A total of 522 strains belonging to streptococci, enterococci and staphylococci isolated from sub-clinical and clinical cases of bovine mastitis from the west littoral region of Uruguay were analysed for their susceptibility to several antimicrobial agents. The susceptibility patterns were studied by agar disk diffusion methods (ADDM) and broth micro-dilution to determine the minimum inhibitory concentration (MIC). The concentration that inhibits 90% (MIC90) of the analysed strains reported in micrograms per millilitre, for Staphylococcus aureus were > 8, 8, ≤ 0.5, ≤ 4, ≤ 1, ≤ 0.5, > 64, ≤ 0.25, 0.5, ≤ 1 and ≤ 1 to penicillin, ampicillin, oxacillin, cephalotin, gentamicin, erythromycin, oxitetracycline, enrofloxacin, trimethoprim/sulfamethoxazole, neomycin, and clindamycin, respectively. Coagulase-negative staphylococci (CNS) had different values for penicillin (4) and ampicillin (2), while the other antimicrobial agents had the same MIC90 values as reported for S. aureus. The MIC90 values for streptococci were 0.12, 0.25, ≤ 4, 16, ≤ 0.25, 0.5, 0.25 for penicillin, ampicillin, cephalotin, gentamicin, erythromycin, oxytetracycline and trimethoprim-sulfamethoxazole, whereas MIC90 for enterococci were 4, 4, 4, ≤ 0.5, 2, > 8 for penicillin, ampicillin, gentamicin, erythromycin, oxytetracycline and trimethoprim-sulfamethoxazole, respectively. Of 336 strains of S. aureus, 160 (47.6%) were resistant to penicillin. For 41 CNS strains, 10 (27%) presented penicillin-resistance. All the streptococcal strains were susceptible to penicillin, while 3 (7%) of the 43 enteroccocal strains were resistant. Non significant statistical differences were found between the results obtained by ADDM and broth micro-dilution for classifying bacterial isolates as susceptible or resistant according to the National Committee of Clinical Laboratory Standards. PMID:12071114

Characterization of riverbed sediments hydraulic conductivity using slug tests and electrical resistivity tomography and induced polarization tomogrpahy.

NASA Astrophysics Data System (ADS)

Nguyen, F.; Benoit, S.; Gommers, K.; Ghysels, G.; Hermans, T.; Huysmans, M.

2017-12-01

Hydraulic conductivity of river sediments ranges from values smaller than 10-9 m/s to values higher than 10-2 m/s, with a dominance in values between 10-7 m/s and 10-3 m/s. Both horizontal hydraulic conductivity and vertical hydraulic conductivity show spatial variation in a riverbed. The spatial variation in hydraulic conductivity is due to the influence of the sedimentary and geomorphological environment as well as the method of determination, including scale, size and imprecision of the applied method. The characterization of the spatial variability of hydraulic conductivity in riverbeds is important because of its effect on the interaction between river and groundwater. These river - groundwater interactions influence water resource management, water quality and functioning of the riparian ecosystem. It is necessary in the simulation of 3D flow between river and aquifer near the interface and thus, it also determines contaminant transport and biogeochemical modelling in this riparian or hyporheic zone. Different processes occur in this specific zone such as transport, degradation, transformation, precipitation and sorption of substances, all dependent on hydraulic conductivity. Several methods exist to determine the hydraulic conductivity in river beds, both direct and indirect methods, from field to laboratory experiments or numerical modelling, but the uncertainty on obtained K values is often large because of the large variability of K. In the recent years, research has been performed on the usefulness of geophysical methods on rivers, in particular Electrical Resistivity Tomography (ERT) and Induced Polarization (IP). The implementation of ERT and IP in rivers provides a continuous image of the resistivity and chargeability of the subsurface, respectively, and can be used in several applications as proxies for hydraulic conductivity. This work reports and investigate a correlation between hydraulic conductivity measured by slug tests at an experimental site, and electrical resistivity, chargeability and normalized chargeability for riverbeds sediments.

An evaluation of the applicability of the telluric-electric and audio-magnetotelluric methods to mineral assessment on the Arabian Shield, Kingdom of Saudi Arabia

USGS Publications Warehouse

Flanigan, Vincent J.; Zablocki, Charles J.

1984-01-01

Feasibility studies of two electromagnetic methods were made in selected areas of the Jabal Hibshi (1:250,000) quadrangle, 26F, in the Kingdom of Saudi Arabia in March of 1983. The methods tested were the natural source-field telluricelectric and audio-magnetotelluric methods developed and extensively used in recent years by the U.S. Geological Survey in some of its domestic programs related to geothermal and mineral resource assessment. Results from limited studies in the Meshaheed district, the Jabal as Silsilah ring complex, and across a portion of the Raha fault zone clearly demonstrate the appropriateness of these sub-regional scale, reconnaissance-type studies to mineral resource assessment. The favorable results obtained are largely attributed to distinctive and large contrasts in the electrical resistivity of the major rock types encountered. It appears that the predominant controlling factor governing the rock resistivities is the amount of contained clay minerals. Accordingly, unaltered (specifically, non-argillic) igneous and metamorphic rocks have very high resistivities; metasedimentary rocks of the Murdama group that contain several percent clay minerals have intermediate values of resistivity; and highly altered rocks, containing abundant clay minerals, have very low values of resistivity. Water-filled fracture porosity may be a secondary, but important, factor in some settings. However, influences from variations in interstitial or intercrystalline, water-filled porosity are probably small because these types of porosity are generally low. It is reasonable to expect similar results in other areas within the Arabian Shield.

Propolis, A Hope for the Future in Treating Resistant Periodontal Pathogens.

PubMed

Shabbir, Ambreen; Rashid, Maryam; Tipu, Hamid N

2016-07-12

Periodontitis is one of the most common causes of tooth loss worldwide. Recently, special attention has been paid to natural medication for its treatment. For this purpose, propolis (bee glue) activity has also been investigated. Its antibacterial properties are mainly attributed to flavonones pinocembrin, flavonols galangin and to the caffeic acid phenethyl ester. This study is aimed at evaluating the antimicrobial effects of propolis from Pakistan on 35 clinical isolates of pigmented anaerobic periodontal pathogens. This study was conducted in the Microbiology department, University of Health Sciences, Lahore, Pakistan. Pathogens included were Porphyromonas asaccharolytica (n=9), Porphyromonas gingivalis (n=13), Prevotella intermedia (n=9), Prevotella melaninogenica (n=4). Minimum inhibitory concentration (MIC) to three antibiotics was obtained by E-test method. All strains were sensitive to amoxicillin plus clavulanic acid and metronidazole, but 100% of P asaccharolytica and P melaninogenica strains displayed intermediate resistance to tetracycline while 69.2% P gingivalis and 100% P intermedia strains exhibited complete resistance to tetracycline. Screening for antibacterial activity of propolis extract was done by agar well diffusion assay, and all strains were found sensitive to ethanolic extract of propolis. MIC was obtained by agar incorporation technique with values ranging from 0.064 to 0.512 mg/ml. It was also noticed that percentage yield of ethanolic extract of propolis prepared from ultrasonic extraction method was higher compared to extract obtained with maceration. These results indicate that propolis from this region has potent antimicrobial activity against pigmented anaerobic periodontal pathogens. Taking into consideration the increasing resistance in anaerobic bacteria, this effective antimicrobial activity of propolis gives hope in the treatment of oral cavity diseases.

Propolis, A Hope for the Future in Treating Resistant Periodontal Pathogens

PubMed Central

Rashid, Maryam; Tipu, Hamid N

2016-01-01

Introduction: Periodontitis is one of the most common causes of tooth loss worldwide. Recently, special attention has been paid to natural medication for its treatment. For this purpose, propolis (bee glue) activity has also been investigated. Its antibacterial properties are mainly attributed to flavonones pinocembrin, flavonols galangin and to the caffeic acid phenethyl ester. This study is aimed at evaluating the antimicrobial effects of propolis from Pakistan on 35 clinical isolates of pigmented anaerobic periodontal pathogens. Methods: This study was conducted in the Microbiology department, University of Health Sciences, Lahore, Pakistan. Pathogens included were Porphyromonas asaccharolytica (n=9), Porphyromonas gingivalis (n=13), Prevotella intermedia (n=9), Prevotella melaninogenica (n=4). Minimum inhibitory concentration (MIC) to three antibiotics was obtained by E-test method. All strains were sensitive to amoxicillin plus clavulanic acid and metronidazole, but 100% of P asaccharolytica and P melaninogenica strains displayed intermediate resistance to tetracycline while 69.2% P gingivalis and 100% P intermedia strains exhibited complete resistance to tetracycline. Screening for antibacterial activity of propolis extract was done by agar well diffusion assay, and all strains were found sensitive to ethanolic extract of propolis. Results: MIC was obtained by agar incorporation technique with values ranging from 0.064 to 0.512 mg/ml. It was also noticed that percentage yield of ethanolic extract of propolis prepared from ultrasonic extraction method was higher compared to extract obtained with maceration. Conclusion: These results indicate that propolis from this region has potent antimicrobial activity against pigmented anaerobic periodontal pathogens. Taking into consideration the increasing resistance in anaerobic bacteria, this effective antimicrobial activity of propolis gives hope in the treatment of oral cavity diseases. PMID:27563508

Comparison of spa Types, SCCmec Types and Antimicrobial Resistance Profiles of MRSA Isolated from Turkeys at Farm, Slaughter and from Retail Meat Indicates Transmission along the Production Chain

PubMed Central

Vossenkuhl, Birgit; Brandt, Jörgen; Fetsch, Alexandra; Käsbohrer, Annemarie; Kraushaar, Britta; Alt, Katja; Tenhagen, Bernd-Alois

2014-01-01

The prevalence of MRSA in the turkey meat production chain in Germany was estimated within the national monitoring for zoonotic agents in 2010. In total 22/112 (19.6%) dust samples from turkey farms, 235/359 (65.5%) swabs from turkey carcasses after slaughter and 147/460 (32.0%) turkey meat samples at retail were tested positive for MRSA. The specific distributions of spa types, SCCmec types and antimicrobial resistance profiles of MRSA isolated from these three different origins were compared using chi square statistics and the proportional similarity index (Czekanowski index). No significant differences between spa types, SCCmec types and antimicrobial resistance profiles of MRSA from different steps of the German turkey meat production chain were observed using Chi-Square test statistics. The Czekanowski index which can obtain values between 0 (no similarity) and 1 (perfect agreement) was consistently high (0.79–0.86) for the distribution of spa types and SCCmec types between the different processing stages indicating high degrees of similarity. The comparison of antimicrobial resistance profiles between the different process steps revealed the lowest Czekanowski index values (0.42–0.56). However, the Czekanowski index values were substantially higher than the index when isolates from the turkey meat production chain were compared to isolates from wild boar meat (0.13–0.19), an example of a separated population of MRSA used as control group. This result indicates that the proposed statistical method is valid to detect existing differences in the distribution of the tested characteristics of MRSA. The degree of similarity in the distribution of spa types, SCCmec types and antimicrobial resistance profiles between MRSA isolates from different process stages of turkey meat production may reflect MRSA transmission along the chain. PMID:24788143

A comparative study of the in vitro corrosion behavior and cytotoxicity of a superferritic stainless steel, a Ti-13Nb-13Zr alloy, and an austenitic stainless steel in Hank's solution.

PubMed

Assis, S L; Rogero, S O; Antunes, R A; Padilha, A F; Costa, I

2005-04-01

In this study, the in vitro corrosion resistance of a superferritic stainless steel in naturally aerated Hank's solution at 37 degrees C has been determined to evaluate the steel for use as a biomaterial. The potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS) were used to determine the corrosion resistance. The polarization results showed very low current densities at the corrosion potential and electrochemical behavior typical of passive metals. At potentials above 0.75 V (SCE), and up to that of the oxygen evolution reaction, the superferritic steel exhibited transpassive behavior followed by secondary passivation. The superferritic stainless steel exhibited high pitting resistance in Hank's solution. This steel did not reveal pits even after polarization to 3000 mV (SCE). The EIS results indicated high impedance values at low frequencies, supporting the results obtained from the polarization measurements. The results obtained for the superferritic steel have been compared with those of the Ti-13Nb-13Zr alloy and an austenitic stainless steel, as Ti alloys are well known for their high corrosion resistance and biocompatibility, and the austenitic stainless steel is widely used as an implant material. The cytotoxicity tests indicated that the superferritic steel, the austenitic steel, and the Ti-13Nb-13Zr alloy were not toxic. Based on corrosion resistance and cytotoxicity results, the superferritic stainless steel can be considered as a potential biomaterial. (c) 2005 Wiley Periodicals, Inc.

Economic Evaluation of Intravenous Immunoglobulin plus Corticosteroids for the Treatment of Steroid-Resistant Chronic Inflammatory Demyelinating Polyradiculoneuropathy in Thailand.

PubMed

Bamrungsawad, Naruemon; Upakdee, Nilawan; Pratoomsoot, Chayanin; Sruamsiri, Rosarin; Dilokthornsakul, Piyameth; Dechanont, Supinya; Wu, David Bin-Chia; Dejthevaporn, Charungthai; Chaiyakunapruk, Nathorn

2016-07-01

Intravenous immunoglobulin (IVIG) has been recommended for steroid-resistant chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). The treatment, however, is very costly to healthcare system, and there remains no evidence of its economic justifiability. This study aimed to conduct an economic evaluation (EE) of IVIG plus corticosteroids in steroid-resistant CIDP in Thailand. A Markov model was constructed to estimate the lifetime costs and outcomes for IVIG plus corticosteroids in comparison with immunosuppressants plus corticosteroids in steroid-resistant CIDP patients from a societal perspective. Efficacy and utility data were obtained from clinical literature, meta-analyses, medical record reviews, and patient interviews. Cost data were obtained from list prices, an electronic hospital database, published source, and patient interviews. All costs [in 2015 US dollars (US$)] and outcomes were discounted at 3 % annually. One-way and probabilistic sensitivity analyses were conducted. In the base-case, the incremental costs and quality-adjusted life years (QALYs) of IVIG plus corticosteroids versus immunosuppressants plus corticosteroids were US$2112.02 and 1.263 QALYs, respectively, resulting in an incremental cost-effectiveness ratio (ICER) of US$1672.71 per QALY gained. Sensitivity analyses revealed that the utility value of disabled patients was the greatest influence on ICER. At a societal willingness-to-pay threshold in Thailand of US$4672 per QALY gained, IVIG plus corticosteroids had a 92.1 % probability of being cost effective. At a threshold of US$4672 per QALY gained, IVIG plus corticosteroids is considered a cost-effective treatment for steroid-resistant CIDP patients in Thailand.

Porosity and hydraulic conductivity estimation of the basaltic aquifer in Southern Syria by using nuclear and electrical well logging techniques

NASA Astrophysics Data System (ADS)

Asfahani, Jamal

2017-08-01

An alternative approach using nuclear neutron-porosity and electrical resistivity well logging of long (64 inch) and short (16 inch) normal techniques is proposed to estimate the porosity and the hydraulic conductivity ( K) of the basaltic aquifers in Southern Syria. This method is applied on the available logs of Kodana well in Southern Syria. It has been found that the obtained K value by applying this technique seems to be reasonable and comparable with the hydraulic conductivity value of 3.09 m/day obtained by the pumping test carried out at Kodana well. The proposed alternative well logging methodology seems as promising and could be practiced in the basaltic environments for the estimation of hydraulic conductivity parameter. However, more detailed researches are still required to make this proposed technique very performed in basaltic environments.

Elastic properties of some transition metal arsenides

NASA Astrophysics Data System (ADS)

Nayak, Vikas; Verma, U. P.; Bisht, P. S.

2018-05-01

The elastic properties of transition metal arsenides (TMAs) have been studied by employing Wien2K package based on density functional theory in the zinc blende (ZB) and rock salt (RS) phase treating valance electron scalar relativistically. Further, we have also treated them non-relativistically to find out the relativistic effect. We have calculated the elastic properties by computing the volume conservative stress tensor for small strains, using the method developed by Charpin. The obtained results are discussed in paper. From the obtained results, it is clear that the values of C11 > C12 and C44 for all the compounds. The values of shear moduli of these compounds are also calculated. The internal parameter for these compounds shows that ZB structures of these compounds have high resistance against bond order. We find that the estimated elastic constants are in good agreement with the available data.

Properties of Josephson Junction Fabricated on Bicrystal Substrate with Different Misorientation Angles

NASA Astrophysics Data System (ADS)

Minotani, Tadashi; Kawakami, Satoru; Kuroki, Yukinori; Enpuku, Keiji

1998-06-01

In order to develop YBa2Cu3O7-δ bicrystal junctions suitable for high-performance superconducting quantum interference device (SQUID), the relationship between the junction properties and the misorientation angle of the bicrystal substrate is studied experimentally. Misorientation angles of 24°, 27°, 30°, 33° and 36.8° are used, and the angular dependencies of junction resistance Rs and critical current Io are investigated. It is shown that values of Rs and Io approximately follow the relation IoRs1.5=const. in these junctions. The obtained results are analyzed in terms of the direct and resonant tunneling mechanisms. It is also shown that values of Rs≈10 Ω and Io≈20 µA can be obtained rather reproducibly when we use the 30° junctions. The properties of this junction are very promising for the development of high-performance SQUID.

Evaluation of mesoporous silicon thermal conductivity by electrothermal finite element simulation

PubMed Central

2012-01-01

The aim of this work is to determine the thermal conductivity of mesoporous silicon (PoSi) by fitting the experimental results with simulated ones. The electrothermal response (resistance versus applied current) of differently designed test lines integrated onto PoSi/silicon substrates and the bulk were compared to the simulations. The PoSi thermal conductivity was the single parameter used to fit the experimental results. The obtained thermal conductivity values were compared with those determined from Raman scattering measurements, and a good agreement between both methods was found. This methodology can be used to easily determine the thermal conductivity value for various porous silicon morphologies. PMID:22849851

Planetary quarantine program

NASA Technical Reports Server (NTRS)

1971-01-01

A quantitative means was developed to investigate the sensitivity of current spacecraft sterilization plans to variations in D-values. A quantitative expression was derived to represent the distribution of D-values among a population of naturally occurring organisms. An investigation was made of (1) the inactivation of both Bacillus subtilis var. niger spores and Cape Kennedy soil spores by gamma-radiation at room temperature in a nitrogen environment, and (2) the thermoradiation resistance of Cape Kennedy soil spores at elevated temperatures below 125 C. The relation between standard survival experiments with bacterial spores in soils and results obtained on spacecraft surfaces is discussed. Sporocidal properties of aqueous formaldehyde can be increased by elevating the temperature.

Association between Triglyceride to HDL-C Ratio (TG/HDL-C) and Insulin Resistance in Chinese Patients with Newly Diagnosed Type 2 Diabetes Mellitus

PubMed Central

Ren, Xingxing; Chen, Zeng.ai; Zheng, Shuang; Han, Tingting; Li, Yangxue; Liu, Wei; Hu, Yaomin

2016-01-01

Objectives To explore the association between the triglyceride to HDL-C ratio (TG/HDL-C) and insulin resistance in Chinese patients with newly diagnosed type 2 diabetes mellitus. Methods Patients with newly diagnosed type 2 diabetes mellitus (272 men and 288 women) were enrolled and divided into three groups according to TG/HDL-C tertiles. Insulin resistance was defined by homeostatic model assessment of insulin resistance (HOMA-IR). Demographic information and clinical characteristics were obtained. Spearman’s correlation was used to estimate the association between TG/HDL-C and other variables. Multiple logistic regression analyses were adopted to obtain probabilities of insulin resistance. A receiver operating characteristic analysis was conducted to evaluate the ability of TG/HDL-C to discriminate insulin resistance. Results TG/HDL-C was associated with insulin resistance in Chinese patients with newly diagnosed T2DM (Spearman’s correlation coefficient = 0.21, P < 0.01). Patients in the higher tertiles of TG/HDL-C had significantly higher HOMA-IR values than patients in the lower tertiles [T1: 2.68(1.74–3.70); T2: 2.96(2.29–4.56); T3: 3.09(2.30–4.99)]. Multiple logistic regression analysis showed that TG/HDL-C was significantly associated with HOMA-IR, and patients in the higher TG/HDL-C tertile had a higher OR than those in the lower TG/HDL-C tertile, after adjusting for multiple covariates including indices for central obesity [T1: 1; T2: 4.02(1.86–8.71); T3: 4.30(1.99–9.29)]. Following stratification of waist circumference into quartiles, the effect of TG/HDL-C on insulin resistance remained significant irrespective of waist circumference. Conclusions TG/HDL-C was associated with insulin resistance independent of waist circumference. Whether it could be a surrogate marker for insulin resistance in Chinese patients with newly diagnosed type 2 diabetes mellitus still needs to be confirmed by more researches. PMID:27115999

RF tissue-heating near metallic implants during magnetic resonance examinations: an approach in the ac limit.

PubMed

Ballweg, Verena; Eibofner, Frank; Graf, Hansjorg

2011-10-01

State of the art to access radiofrequency (RF) heating near implants is computer modeling of the devices and solving Maxwell's equations for the specific setup. For a set of input parameters, a fixed result is obtained. This work presents a theoretical approach in the alternating current (ac) limit, which can potentially render closed formulas for the basic behavior of tissue heating near metallic structures. Dedicated experiments were performed to support the theory. For the ac calculations, the implant was modeled as an RLC parallel circuit, with L being the secondary of a transformer and the RF transmission coil being its primary. Parameters influencing coupling, power matching, and specific absorption rate (SAR) were determined and formula relations were established. Experiments on a copper ring with a radial gap as capacitor for inductive coupling (at 1.5 T) and on needles for capacitive coupling (at 3 T) were carried out. The temperature rise in the embedding dielectric was observed as a function of its specific resistance using an infrared (IR) camera. Closed formulas containing the parameters of the setup were obtained for the frequency dependence of the transmitted power at fixed load resistance, for the calculation of the resistance for optimum power transfer, and for the calculation of the transmitted power in dependence of the load resistance. Good qualitative agreement was found between the course of the experimentally obtained heating curves and the theoretically determined power curves. Power matching revealed as critical parameter especially if the sample was resonant close to the Larmor frequency. The presented ac approach to RF heating near an implant, which mimics specific values for R, L, and C, allows for closed formulas to estimate the potential of RF energy transfer. A first reference point for worst-case determination in MR testing procedures can be obtained. Numerical approaches, necessary to determine spatially resolved heating maps, can be supported.

A two dimension model of the uterine electrical wave propagation.

PubMed

Rihana, S; Lefrançois, E; Marque, C

2007-01-01

The uterus, usually quiescent during pregnancy, exhibits forceful contractions at term leading to delivery. These contractions are caused by the synchronized propagation of electrical waves from the pacemaker cells to its neighbors inducing the whole coordinated contraction of the uterus wall leading to labor. In a previous work, we simulate the electrical activity of a single uterine cell by a set of ordinary differential equations. Then, this model has been used to simulate the electrical activity propagation. In the present work, the uterine cell tissue is assumed to have uniform and isotropic propagation, and constant electrical membrane properties. The stability of the numerical solution imposes the choice of a critical temporal step. A wave starts at a pacemaker cell; this electrical activity is initiated by the injection of an external stimulation current to the cell membrane. We observe synchronous wave propagation for axial resistance values around 0.5 GOmega or less and propoagation blocking for values greater than 0.7 GOmega. We compute the conduction velocity of the excitation, for different axial resistance values, and obtain a velocity about 10 cm/sec, approaching the one described by the literature for the rat at end of term.

Correlation between magnetocaloric and electrical properties based on phenomenological models in La0.47Pr0.2Pb0.33MnO3 perovskite

NASA Astrophysics Data System (ADS)

Mechi, Nesrine; Alzahrani, Bandar; Hcini, Sobhi; Bouazizi, Mohamed Lamjed; Dhahri, Abdessalem

2018-06-01

We have investigated the correlation between magnetocaloric and electrical properties of La0.47Pr0.2Pb0.33MnO3 perovskite prepared using the sol-gel method. Rietveld analysis of X-ray diffraction (XRD) pattern shows pure crystalline phase with rhombohedral ? structure. Magnetic entropy change, relative cooling power (RCP) and specific heat were predicted from M(T, μ0H) data at different magnetic fields with the help of the phenomenological model. The magnetic entropy change reaches a maximum value ? of about 3.96 J kg-1 K-1 for μ0H = 5 T corresponding to RCP of 183 J kg-1. These values are relatively higher, making our sample a promising candidate for the magnetic refrigeration. Electrical-resistivity measurements were well fitted with the phenomenological percolation model, which is based on the phase segregation of ferromagnetic-metallic clusters and paramagnetic-semiconductor regions. The temperature and magnetic field dependences of resistivity data, ρ(T, μ0H), allowed us to determine the magnetic entropy change ?. Results show that the as-obtained magnetic entropy change values are similar to those determined from the phenomenological model.

Creep and stress rupture of oxide dispersion strengthened mechanically alloyed Inconel alloy MA 754

NASA Technical Reports Server (NTRS)

Howson, T. E.; Tien, J. K.; Stulga, J. E.

1980-01-01

The creep and stress rupture behavior of the mechanically alloyed oxide dispersion strengthened nickel-base alloy MA 754 was studied at 760, 982 and 1093 C. Tensile specimens with a fine, highly elongated grain structure, oriented parallel and perpendicular to the longitudinal grain direction were tested at various stresses in air under constant load. It was found that the apparent stress dependence was large, with power law exponents ranging from 19 to 33 over the temperature range studied. The creep activation energy, after correction for the temperature dependence of the elastic modulus, was close to but slightly larger than the activation energy for self diffusion. Rupture was intergranular and the rupture ductility as measured by percentage elongation was generally low, with values ranging from 0.5 to 16 pct. The creep properties are rationalized by describing the creep rates in terms of an effective stress which is the applied stress minus a resisting stress consistent with the alloy microstructure. Values of the resisting stress obtained through a curve fitting procedure are found to be close to the values of the particle by-pass stress for this oxide dispersion strengthened alloy, as calculated from the measured oxide particle distribution.

Development of microheaters for gas sensor with an AT-Mega 8535 temperature controller using a PWM (pulse width modulation) method

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

Megayanti, Meti; Panatarani, Camellia; Joni, I. Made, E-mail: imadejoni@phys.unpad.ac.id

Microheater is the main component in gas sensor characterized by their sensitivity, selectivity, and time response of gas sensor which is depend on the microheater temperature stability. A Cu microheater was developed and utilized AT-Mega 8535 controller using a PWM (pulse width modulation) method. This control system is interfaced to the PC to observe the real time temperature response of the microheater. Three initial resistance (R0) variations of microheater were developed in an open loop control system. The power characteristic of designed microheater depends on the specified microheater initial resistance. The smaller R0, the less power required to reach amore » temperature setting value. The developed microheater was designed to reach a temperature setting value of 250°C having resistance 0.531 Ω for 1.979 Watt and 0.265 Ω for 1.072 Watt respectively. The results of the investigation on the control performances shows microheater-control system achieved operating temperature up to 250°C. The response of the temperature control shows smallest R0 resulted in a high stability with short settling time, short delay time and small ripple for temperature setting values higher than 150°C. The obtained error of microheater temperature with R0 = 0.265 is 8.596 %. It is concluded that the developed microheater can be utilized as a component of a gas sensor.« less

Application of galvanomagnetic measurements in temperature range 70-300 K to MBE GaAs layers characterization

NASA Astrophysics Data System (ADS)

Wolkenberg, Andrzej; Przeslawski, Tomasz

1996-04-01

Galvanomagnetic measurements were performed on the square shaped samples after Van der Pauw and on the Hall bar at low electric fields app. 1.5 V/cm and magnetic induction app. 6 kG in order to make a comparison between the theoretical and experimental results of the temperature dependence of mobility and resistivity from 70 K to 300 K. A calculation method was obtained of the drift mobility and the Hall mobility in which the scatterings are applied: on ionized impurities, on polar optical phonons, on acoustic phonons (deformation potential), on acoustic phonons (piezoelectric potential) and on dislocations. The elaborated method transformed to a computer program allows us to fit experimental values of the resistivity and the Hall mobility to those calculated. The fitting procedure makes it possible to characterize the quality of the n-type GaAs MBE layer, i.e. the net electron concentration, whole ionized impurities concentration and dislocation density after Read space charge cylinders model. The calculations together with the measurements allow us to obtain compensation ratio value in the layer, too. The influence of the epitaxial layer thickness on layers measurements accuracy in the case of Van der Pauw square probe was investigated. It was stated that in the layers under 3 micrometer the bulk properties are strongly influenced by both surfaces. The results of measurements of the same layer using the Van der Pauw and the Hall bar structure were compared. It was stated that the Hall bar structure only could be used to obtain proper measurements results.

Cassia Cinnamon Supplementation Reduces Peak Blood Glucose Responses but Does Not Improve Insulin Resistance and Sensitivity in Young, Sedentary, Obese Women.

PubMed

Gutierrez, Jean L; Bowden, Rodney G; Willoughby, Darryn S

2016-01-01

Cassia cinnamon has been suggested to lower blood glucose (BG) and serum insulin (SI) due to an improvement in insulin resistance (IR) and sensitivity (IS). This study compared the effects Cassia cinnamon had on calculated IR and IS values and BG and SI in response to an oral glucose tolerance test (OGTT) in young, sedentary, and obese women. On three separate days, 10 women had a fasted venous blood sample obtained. Participants were given 5 g of encapsulated placebo (PLC) or 5 g of encapsulated Cassia cinnamon bark (CASS). Three hours after the initial blood sample, another blood sample was obtained to calculate values for IS and IR. The participants then completed an OGTT by consuming a 75 g glucose solution. Blood was obtained 30, 60, 90, and 120 min following glucose ingestion. IS and IR were not significantly different between placebo and Cassia (p > .05). The peak BG concentration in response to the OGTT was significantly lower at the 30 min time point for CASS, as compared to PLC (140 ± 5.8 and 156 ± 5.2 mg/dL, p = .025); however, there was no significant difference between treatments for SI (p > .05). The area-under-the-curve responses for BG and SI were not significantly different between PLC and CASS (p > .05). This study suggests that a 5 g dose of Cassia cinnamon may reduce the peak BG response and improve glucose tolerance following an OGTT, but with no improvement in IS and IR in young, sedentary, obese women.

Devices for SRF material characterization

DOE PAGES

Goudket, Philippe; Xiao, B.; Junginger, T.

2016-10-07

The surface resistance Rs of superconducting materials can be obtained by measuring the quality factor of an elliptical cavity excited in a transverse magnetic mode (TM010). The value obtained has however to be taken as averaged over the whole surface. A more convenient way to obtain Rs, especially of materials which are not yet technologically ready for cavity production, is to measure small samples instead. These can be easily man ufactured at low cost, duplicated and placed in film deposition and surface analytical tools. A commonly used design for a device to measure Rs consists of a cylindrical cavity excitedmore » in a transverse electric (TE110) mode with the sample under test serving as one replaceable endplate. Such a cavity has two drawbacks. For reasonably small samples the resonant frequency will be larger than frequencies of interest concerning SRF application and it requires a reference sample of known Rs. In this article we review several devices which have been designed to overcome these limitations, reaching sub - nΩ resolution in some cases. Some of these devices also comprise a parameter space in frequency and temperature which is inaccessible to standard cavity tests, making them ideal tools to test theoretical surface resistance models.« less

Analysis of projectile motion: A comparative study using fractional operators with power law, exponential decay and Mittag-Leffler kernel

NASA Astrophysics Data System (ADS)

Gómez-Aguilar, J. F.; Escobar-Jiménez, R. F.; López-López, M. G.; Alvarado-Martínez, V. M.

2018-03-01

In this paper, the two-dimensional projectile motion was studied; for this study two cases were considered, for the first one, we considered that there is no air resistance and, for the second case, we considered a resisting medium k . The study was carried out by using fractional calculus. The solution to this study was obtained by using fractional operators with power law, exponential decay and Mittag-Leffler kernel in the range of γ \\in (0,1] . These operators were considered in the Liouville-Caputo sense to use physical initial conditions with a known physical interpretation. The range and the maximum height of the projectile were obtained using these derivatives. With the aim of exploring the validity of the obtained results, we compared our results with experimental data given in the literature. A multi-objective particle swarm optimization approach was used for generating Pareto-optimal solutions for the parameters k and γ for different fixed values of velocity v0 and angle θ . The results showed some relevant qualitative differences between the use of power law, exponential decay and Mittag-Leffler law.

Devices for SRF material characterization

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

Goudket, Philippe; Xiao, B.; Junginger, T.

The surface resistance Rs of superconducting materials can be obtained by measuring the quality factor of an elliptical cavity excited in a transverse magnetic mode (TM010). The value obtained has however to be taken as averaged over the whole surface. A more convenient way to obtain Rs, especially of materials which are not yet technologically ready for cavity production, is to measure small samples instead. These can be easily man ufactured at low cost, duplicated and placed in film deposition and surface analytical tools. A commonly used design for a device to measure Rs consists of a cylindrical cavity excitedmore » in a transverse electric (TE110) mode with the sample under test serving as one replaceable endplate. Such a cavity has two drawbacks. For reasonably small samples the resonant frequency will be larger than frequencies of interest concerning SRF application and it requires a reference sample of known Rs. In this article we review several devices which have been designed to overcome these limitations, reaching sub - nΩ resolution in some cases. Some of these devices also comprise a parameter space in frequency and temperature which is inaccessible to standard cavity tests, making them ideal tools to test theoretical surface resistance models.« less

Dimension- and shape-dependent thermal transport in nano-patterned thin films investigated by scanning thermal microscopy

NASA Astrophysics Data System (ADS)

Ge, Yunfei; Zhang, Yuan; Weaver, Jonathan M. R.; Dobson, Phillip S.

2017-12-01

Scanning thermal microscopy (SThM) is a technique which is often used for the measurement of the thermal conductivity of materials at the nanometre scale. The impact of nano-scale feature size and shape on apparent thermal conductivity, as measured using SThM, has been investigated. To achieve this, our recently developed topography-free samples with 200 and 400 nm wide gold wires (50 nm thick) of length of 400-2500 nm were fabricated and their thermal resistance measured and analysed. This data was used in the development and validation of a rigorous but simple heat transfer model that describes a nanoscopic contact to an object with finite shape and size. This model, in combination with a recently proposed thermal resistance network, was then used to calculate the SThM probe signal obtained by measuring these features. These calculated values closely matched the experimental results obtained from the topography-free sample. By using the model to analyse the dimensional dependence of thermal resistance, we demonstrate that feature size and shape has a significant impact on measured thermal properties that can result in a misinterpretation of material thermal conductivity. In the case of a gold nanowire embedded within a silicon nitride matrix it is found that the apparent thermal conductivity of the wire appears to be depressed by a factor of twenty from the true value. These results clearly demonstrate the importance of knowing both probe-sample thermal interactions and feature dimensions as well as shape when using SThM to quantify material thermal properties. Finally, the new model is used to identify the heat flux sensitivity, as well as the effective contact size of the conventional SThM system used in this study.

Predictor-based multivariable closed-loop system identification of the EXTRAP T2R reversed field pinch external plasma response

NASA Astrophysics Data System (ADS)

Olofsson, K. Erik J.; Brunsell, Per R.; Rojas, Cristian R.; Drake, James R.; Hjalmarsson, Håkan

2011-08-01

The usage of computationally feasible overparametrized and nonregularized system identification signal processing methods is assessed for automated determination of the full reversed-field pinch external plasma response spectrum for the experiment EXTRAP T2R. No assumptions on the geometry of eigenmodes are imposed. The attempted approach consists of high-order autoregressive exogenous estimation followed by Markov block coefficient construction and Hankel matrix singular value decomposition. It is seen that the obtained 'black-box' state-space models indeed can be compared with the commonplace ideal magnetohydrodynamics (MHD) resistive thin-shell model in cylindrical geometry. It is possible to directly map the most unstable autodetected empirical system pole to the corresponding theoretical resistive shell MHD eigenmode.

Structural, transport and microwave properties of 123/sapphire films: Thickness effect

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

Predtechensky, MR.; Smal, A.N.; Varlamov, Y.D.

1994-12-31

The effect of thickness and growth conditions on the structure and microwave properties has been investigated for the 123/sapphire films. It has been shown that in the conditions of epitaxial growth and Al atoms do not diffuse from substrate into the film and the films with thickness up to 100nm exhibit the excellent DC properties. The increase of thickness of GdBaCuO films causes the formation of extended line-mesh defects and the increase of the surface resistance (R{sub S}). The low value of surface resistance R{sub S}(75GHz,77K)=20 mOhm has been obtained for the two layer YBaCuO/CdBaCuO/sapphire films.

Efficient spin-filtering, magnetoresistance and negative differential resistance effects of a one-dimensional single-molecule magnet Mn(dmit)2-based device with graphene nanoribbon electrodes

NASA Astrophysics Data System (ADS)

Liu, N.; Liu, J. B.; Yao, K. L.

2017-12-01

We present first-principle spin-dependent quantum transport calculations in a molecular device constructed by one single-molecule magnet Mn(dmit)2 and two graphene nanoribbon electrodes. Our results show that the device could generate perfect spin-filtering performance in a certain bias range both in the parallel configuration (PC) and the antiparallel configuration (APC). At the same time, a magnetoresistance effect, up to a high value of 103%, can be realized. Moreover, visible negative differential resistance phenomenon is obtained for the spin-up current of the PC. These results suggest that our one-dimensional molecular device is a promising candidate for multi-functional spintronics devices.

Diffusion in liquid metal systems. [information on electrical resistivity and thermal conductivity

NASA Technical Reports Server (NTRS)

Ukanwa, A. O.

1975-01-01

Physical properties of twenty liquid metals are reported; some of the data on such liquid metal properties as density, electrical resistivity, thermal conductivity, and heat capacity are summarized in graphical form. Data on laboratory handling and safety procedure are summarized for each metal; heat-transfer-correlations for liquid metals under various conditions of laminar and turbulent flow are included. Where sufficient data were available, temperature equations of properties were obtained by the method of least-squares fit. All values of properties given are valid in the given liquid phase ranges only. Additional tabular data on some 40 metals are reported in the appendix. Included is a brief description of experiments that were performed to investigate diffusion in liquid indium-gallium systems.

Analysis of Laser Injection Condition and Electrical Properties in Local BSF for Laser Fired Contact c-Si Solar Cell Applications.

PubMed

Park, Cheolmin; Choi, Gyuho; Balaji, Nagarajan; Ju, Minkyu; Lee, Youn-Jung; Lee, Haeseok; Yi, Junsin

2018-07-01

A crystalline silicon (c-Si) local-back-contact (LBC) solar cell for which a laser-condition-optimized surface-recombination velocity (SRV), a contact resistance (Rc), and local back surface fields (LBSFs) were utilized is reported. The effect of the laser condition on the rear-side electrical properties of the laser-fired LBC solar cell was studied. The Nd:YAG-laser (1064-nm wavelength) power and frequency were varied to obtain LBSF values with a lower contact resistance. A 10-kHz laser power of 44 mW resulted in an Rc of 0.125 ohms with an LBSF thickness of 2.09 μm and a higher open-circuit voltage (VOC) of 642 mV.

Identification of Sungai Batu Sediment using 2-D Resistivity Imaging and Seismic Refraction Methods for Ancient River Mapping at Kedah, Malaysia

NASA Astrophysics Data System (ADS)

Andika, F.; Saad, R.; Saidin, M. M.; Muztaza, N. M.; Amsir

2018-04-01

Sungai Batu is an earliest civilization in Southeast Asia with evidenced by the discovery of riverside jetty, iron smelting, and ritual monuments. The evidences can lead to prediction of buried river caused by geological and sedimentation process. This study was conducted to study sediment deposit characteristic and to map thickness of the sediments using 2-D resistivity imaging and seismic refraction for ancient river mapping. A total of thirty, 2-D resistivity and nine seismic survey lines were conducted at the study area. Four of the lines R1-R4 and S1-S4 were correlated and validated with existing on site boreholes BH1-BH4 to identify sediment type and thickness. The validated values applied to the remaining survey lines which no borehole record to map the subsurface of the study area. Based on the results, Sungai Batu area consist of clay with resistivity value of 6.6-25.9 Ω.m and velocity value of 716.9-1606.9 m/s; sandy clay with resistivity value of 6-265.1 Ω.m and velocity value of 1003.6-1901.4 m/s; while shale was identified with resistivity value of >668.6 Ω.m and velocity value of >2051.7 m/s. Boundary between clay/sandy clay with shale was identified with resistivity value of 314 Ω.m and velocity value of 1822 m/s. The integration of the 2-D resistivity and seismic refraction identified that the thickness of Sungai Batu sediment is 0-150 m and Sungai Batu ancient river was successfully map based on thickness of sediment which is >45 m.

ERT and Well Data Tie for Nickel Laterite Characterization

NASA Astrophysics Data System (ADS)

Aswad, Sabrianto; Mamela Mais, Difar; Syamsuddin; Wanni

2018-03-01

The need of ERT method in nickel latentes exploration can’t be deny. This method have capability to make exploration more effective and efficient. In reality this method still remain ambiguity in its application, especially for geologist and mining expert. These ambiguity related with layer zone determination (limonite, saprolite and bedrock), the same resistivity values in the different zones and determination of bedrock. This paper try to expose interesting fact to overcome this ambiguity by using ERT data and drill data tie. This tie will show characteristic of nickel lateric based on resisitivity value and the contribution of chemistry element for resistivity value. Data ERT was collected by using gradient configuration and well data consist of mayor element and minor element. Tie result showed difference resistivity value in limonite layer influence by Fe, H2O and Ni, where resistivity value from saprolite layer influenced by Fe, H2O, Si02, MgO, Al, Cr, and Ni in certain accumulation. In bedrock layer, almost all drill data did not reach bedrock but only reached the boulder alone, it is supported by the value of the resistivity of rock unserpentinized peridotite which should show a relatively large resistivity value

An Improved Method for Measuring Quantitative Resistance to the Wheat Pathogen Zymoseptoria tritici Using High-Throughput Automated Image Analysis.

PubMed

Stewart, Ethan L; Hagerty, Christina H; Mikaberidze, Alexey; Mundt, Christopher C; Zhong, Ziming; McDonald, Bruce A

2016-07-01

Zymoseptoria tritici causes Septoria tritici blotch (STB) on wheat. An improved method of quantifying STB symptoms was developed based on automated analysis of diseased leaf images made using a flatbed scanner. Naturally infected leaves (n = 949) sampled from fungicide-treated field plots comprising 39 wheat cultivars grown in Switzerland and 9 recombinant inbred lines (RIL) grown in Oregon were included in these analyses. Measures of quantitative resistance were percent leaf area covered by lesions, pycnidia size and gray value, and pycnidia density per leaf and lesion. These measures were obtained automatically with a batch-processing macro utilizing the image-processing software ImageJ. All phenotypes in both locations showed a continuous distribution, as expected for a quantitative trait. The trait distributions at both sites were largely overlapping even though the field and host environments were quite different. Cultivars and RILs could be assigned to two or more statistically different groups for each measured phenotype. Traditional visual assessments of field resistance were highly correlated with quantitative resistance measures based on image analysis for the Oregon RILs. These results show that automated image analysis provides a promising tool for assessing quantitative resistance to Z. tritici under field conditions.

Outdoor ground impedance models.

PubMed

Attenborough, Keith; Bashir, Imran; Taherzadeh, Shahram

2011-05-01

Many models for the acoustical properties of rigid-porous media require knowledge of parameter values that are not available for outdoor ground surfaces. The relationship used between tortuosity and porosity for stacked spheres results in five characteristic impedance models that require not more than two adjustable parameters. These models and hard-backed-layer versions are considered further through numerical fitting of 42 short range level difference spectra measured over various ground surfaces. For all but eight sites, slit-pore, phenomenological and variable porosity models yield lower fitting errors than those given by the widely used one-parameter semi-empirical model. Data for 12 of 26 grassland sites and for three beech wood sites are fitted better by hard-backed-layer models. Parameter values obtained by fitting slit-pore and phenomenological models to data for relatively low flow resistivity grounds, such as forest floors, porous asphalt, and gravel, are consistent with values that have been obtained non-acoustically. Three impedance models yield reasonable fits to a narrow band excess attenuation spectrum measured at short range over railway ballast but, if extended reaction is taken into account, the hard-backed-layer version of the slit-pore model gives the most reasonable parameter values.

Antimicrobial susceptibility and antibiotic resistance gene transfer analysis of foodborne, clinical, and environmental Listeria spp. isolates including Listeria monocytogenes.

PubMed

Bertsch, David; Muelli, Mirjam; Weller, Monika; Uruty, Anaïs; Lacroix, Christophe; Meile, Leo

2014-02-01

The aims of this study were to assess antibiotic resistance pheno- and genotypes in foodborne, clinical, and environmental Listeria isolates, as well as to elucidate the horizontal gene transfer potential of detected resistance genes. A small fraction of in total 524 Listeria spp. isolates (3.1%) displayed acquired antibiotic resistance mainly to tetracycline (n = 11), but also to clindamycin (n = 4) and trimethoprim (n = 3), which was genotypically confirmed. In two cases, a tetracycline resistance phenotype was observed together with a trimethoprim resistance phenotype, namely in a clinical L. monocytogenes strain and in a foodborne L. innocua isolate. Depending on the applied guidelines, a differing number of isolates (n = 2 or n = 20) showed values for ampicillin that are on the edge between intermediate susceptibility and resistance. Transferability of the antibiotic resistance genes from the Listeria donors, elucidated in vitro by filter matings, was demonstrated for genes located on transposons of the Tn916 family and for an unknown clindamycin resistance determinant. Transfer rates of up to 10(-5) transconjugants per donor were obtained with a L. monocytogenes recipient and up to 10(-7) with an Enterococcus faecalis recipient, respectively. Although the prevalence of acquired antibiotic resistance in Listeria isolates from this study was rather low, the transferability of these resistances enables further spread in the future. This endorses the importance of surveillance of L. monocytogenes and other Listeria spp. in terms of antibiotic susceptibility. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

The effect of various backfilling techniques on the fracture resistance of simulated immature teeth performed apical plug with Biodentine.

PubMed

Topçuoğlu, Hüseyin Sinan; Kesim, Bertan; Düzgün, Salih; Tuncay, Öznur; Demirbuga, Sezer; Topçuoğlu, Gamze

2015-07-01

To evaluate the fracture resistance of simulated immature teeth that had been backfilled using different materials after using Biodentine as the apical plug material. Seventy-five single-rooted teeth were divided into five groups (n = 15). The 15 teeth in group 1 served as a negative control group and received no treatment. The remaining 60 teeth were instrumented to a #6 Peeso reamer to obtain a standard internal diameter of 1.5 mm. The apical 4 mm of 60 teeth was filled with Biodentine. The backfilling was then performed on each group as follows: group 2--no backfilling (positive control), group 3--gutta-percha, group 4--fiber post, and group 5--Biodentine. Specimens were then subjected to fracture testing. The force required to fracture each specimen was recorded, and the data were statistically analyzed. The mean fracture values of groups 1 and 4 were significantly higher than groups 2, 3, and 5 (P < 0.05). The values of groups 3 and 5 were significantly higher than group 2 (P < 0.05). The backfilling with fiber post after an apical Biodentine plug provided the highest fracture resistance among all experimental groups. © 2014 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Assessment of electrochemical properties of a biogalvanic system for tissue characterisation

PubMed Central

Chandler, J.H.; Culmer, P.R.; Jayne, D.G.; Neville, A.

2015-01-01

Biogalvanic characterisation is a promising method for obtaining health-specific tissue information. However, there is a dearth of understanding in the literature regarding the underlying galvanic cell, electrode reactions and their controlling factors which limits the application of the technique. This work presents a parametric electrochemical investigation into a zinc–copper galvanic system using salt (NaCl) solution analogues at physiologically-relevant concentrations (1.71, 17.1 & 154 mM). The potential difference at open cell, closed cell maximum current and the internal resistance (based on published characterisation methods) were measured. Additionally, independent and relative polarisation scans of the electrodes were performed to improve understanding of the system. Our findings suggest that the prominent reaction at the cathode is that of oxygen-reduction, not hydrogen-evolution. Results indicate that cell potentials are influenced by the concentration of dissolved oxygen at low currents and maximum closed cell currents are limited by the rate of oxygen diffusion to the cathode. Characterised internal resistance values for the salt solutions did not correspond to theoretical values at the extremes of concentration (1.71 and 154 mM) due to electrode resistance and current limitation. Existing biogalvanic models do not consider these phenomena and should be improved to advance the technique and its practical application. PMID:25460609

Experimental Investigations on the Pull-Out Behavior of Tire Strips Reinforced Sands.

PubMed

Li, Li-Hua; Chen, Yan-Jun; Ferreira, Pedro Miguel Vaz; Liu, Yong; Xiao, Heng-Lin

2017-06-27

Waste tires have excellent mechanical performance and have been used as reinforcing material in geotechnical engineering; however, their interface properties are poorly understood. To further our knowledge, this paper examines the pull-out characteristics of waste tire strips in a compacted sand, together with uniaxial and biaxial geogrids also tested under the same conditions. The analysis of the results shows that the interlocking effect and pull-out resistance between the tire strip and the sand is very strong and significantly higher than that of the geogrids. In the early stages of the pull-out test, the resistance is mainly provided by the front portion of the embedded tire strips, as the pull-out test continues, more and more of the areas towards the end of the tire strips are mobilized, showing a progressive failure mechanism. The deformations are proportional to the frictional resistance between the tire-sand interface, and increase as the normal stresses increase. Tire strips of different wear intensities were tested and presented different pull-out resistances; however, the pull-out resistance mobilization patterns were generally similar. The pull-out resistance values obtained show that rubber reinforcement can provide much higher pull-out forces than the geogrid reinforcements tested here, showing that waste tires are an excellent alternative as a reinforcing system, regardless of the environmental advantages.

Monolithic 20W 2GHz Transistor and Monolithic 5W 4GHz Transistor.

DTIC Science & Technology

1979-02-01

epitaxial material of better quality than has been obtained from outside vendors . Ini tial tests indicate that the intrinsic material grown in our...system exceeds 800~ —cm , which is at least twice the value required . Also , the correct substrate material will be used and the N buried layer will...be the correct resistivity and thickness. The N layer will also be deposited somewhat thinner than the exist- ing material to reduce the collector

Identification of novel tyrosine kinase inhibitors for drug resistant T315I mutant BCR-ABL: a virtual screening and molecular dynamics simulations study

NASA Astrophysics Data System (ADS)

Banavath, Hemanth Naick; Sharma, Om Prakash; Kumar, Muthuvel Suresh; Baskaran, R.

2014-11-01

BCR-ABL tyrosine kinase plays a major role in the pathogenesis of chronic myeloid leukemia (CML) and is a proven target for drug development. Currently available drugs in the market are effective against CML; however, side-effects and drug-resistant mutations in BCR-ABL limit their full potential. Using high throughput virtual screening approach, we have screened several small molecule databases and docked against wild-type and drug resistant T315I mutant BCR-ABL. Drugs that are currently available, such as imatinib and ponatinib, were also docked against BCR-ABL protein to set a cutoff value for our screening. Selected lead compounds were further evaluated for chemical reactivity employing density functional theory approach, all selected ligands shows HLG value > 0.09900 and the binding free energy between protein-ligand complex interactions obtained was rescored using MM-GBSA. The selected compounds showed least ΔG score -71.53 KJ/mol to maximum -126.71 KJ/mol in both wild type and drug resistant T315I mutant BCR-ABL. Following which, the stability of the docking complexes were evaluated by molecular dynamics simulation (MD) using GROMACS4.5.5. Results uncovered seven lead molecules, designated with Drug-Bank and PubChem ids as DB07107, DB06977, ST013616, DB04200, ST007180 ST019342, and DB01172, which shows docking scores higher than imatinib and ponatinib.

Assessment of insulin resistance in lean women with polycystic ovary syndrome.

PubMed

Morciano, Andrea; Romani, Federica; Sagnella, Francesca; Scarinci, Elisa; Palla, Carola; Moro, Francesca; Tropea, Anna; Policola, Caterina; Della Casa, Silvia; Guido, Maurizio; Lanzone, Antonio; Apa, Rosanna

2014-07-01

To develop and validate a specific simple measure of insulin sensitivity using oral glucose tolerance test (OGTT) values for lean polycystic ovary syndrome (PCOS) women. Retrospective study. Gynecologic Outpatient Clinic of University Hospital, affiliated with Unit of Gynecologic Endocrinology. Totals of 201 lean and 198 overweight/obese (ov-ob) nondiabetic PCOS patients were retrospectively selected. None. All patients underwent OGTT, euglycemic-hyperinsulinemic clamp, and androgenic and biochemical assays. The predictive performance of each insulin resistance (IR) index was analyzed with the use of receiver operating characteristic (ROC) curves. Higher correlation coefficients with clamp studies were obtained with the Belfiore Area (RS=0.579) and the homeostasis-model assessment (HOMA)-M120 (RS=-0.576) in lean PCOS patients and with the Sib (RS=0.697) in ov-ob PCOS patients. The best predictive index of IR in lean PCOS was a HOMA-M120 value of ≥12.8 or more (area under the ROC curve [AUC] 92.4%). In the ov-ob PCOS population, the best predictive performance was obtained by a Sib of ≤10.2 or less (AUC 85.7%). IR should be assessed in all PCOS women, both lean and ov-ob subjects. The HOMA-M120 resulted as a very simple tool, validated specifically for the lean PCOS woman whose cardiometabolic impairment is more frequently misunderstood. Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

In vitro assessment of the antimicrobial susceptibility of caprine isolates of Mycoplasma mycoides subsp. capri.

PubMed

Paterna, A; Tatay-Dualde, J; Amores, J; Prats-van der Ham, M; Sánchez, A; de la Fe, C; Contreras, A; Corrales, J C; Gómez-Martín, Á

2016-08-01

The minimum inhibitory concentration (MIC) and minimum mycoplasmacidal concentration (MMC) of 17 antimicrobials against 41 Spanish caprine isolates of Mycoplasma mycoides subsp. capri (Mmc) obtained from different specimens (milk, external auricular canal and semen) were determined using a liquid microdilution method. For half of the isolates, the MIC was also estimated for seven of the antimicrobials using an epsilometric test (ET), in order to compare both methods and assess the validity of ET. Mutations in genes gyrA, gyrB, parC and parE conferring fluoroquinolone resistance, which have been recently described in Mmc, were investigated using PCR. The anatomical origin of the isolate had no effect on its antimicrobial susceptibility. Moxifloxacin and doxycycline had the lowest MIC values. The rest of the fluoroquinolones studied (except norfloxacin), together with tylosin and clindamycin, also had low MIC values, although the MMC obtained for clindamycin was higher than for the other antimicrobials. For all the aminoglycosides, spiramycin and erythromycin, a notable level of resistance was observed. The ET was in close agreement with broth microdilution at low MICs, but not at intermediate or high MICs. The analysis of the genomic sequences revealed the presence of an amino acid substitution in codon 83 of the gene gyrA, which has not been described previously in Mmc. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rapid Thermal Annealing for Solution Synthesis of Transparent Conducting Aluminum Zinc Oxide Thin Films

NASA Astrophysics Data System (ADS)

Ullah, Sana; De Matteis, Fabio; Davoli, Ivan

2017-11-01

Transparent conducting oxide films with optimized dopant molar ratio have been prepared with limited pre- and postdeposition annealing duration of 10 min. Multiple aluminum zinc oxide (AZO) layers were spin-coated on ordinary glass substrates. The predeposition consolidation temperature and dopant molar ratio were optimized for electrical conductivity and optical transparency. Next, a group of films were deposited on Corning glass substrates from precursor solutions with the optimized dopant ratio, followed by postdeposition rapid thermal annealing (RTA) at different temperatures and in controlled environments. The lowest resistivity of 10.1 × 10-3 Ω cm was obtained for films receiving RTA at 600°C for 10 min each in vacuum then in N2-5%H2 environment, while resistivity of 20.3 × 10-3 Ω cm was obtained for films subjected to RTA directly in N2-5%H2. Optical measurements revealed average total transmittance of about 85% in the visible region. A direct allowed transition bandgap was determined based on the absorption edge with a value slightly above 3.0 eV, within the typical range for semiconductors. RTA resulted in desorption of oxygen with enhanced carrier concentration and crystallinity, which increased the carrier mobility with decreased bulk resistivity while maintaining the required optical transparency.

Flow resistance dynamics in step‐pool channels: 2. Partitioning between grain, spill, and woody debris resistance

USGS Publications Warehouse

Wilcox, Andrew C.; Nelson, Jonathan M.; Wohl, Ellen E.

2006-01-01

In step‐pool stream channels, flow resistance is created primarily by bed sediments, spill over step‐pool bed forms, and large woody debris (LWD). In order to measure resistance partitioning between grains, steps, and LWD in step‐pool channels we completed laboratory flume runs in which total resistance was measured with and without grains and steps, with various LWD configurations, and at multiple slopes and discharges. Tests of additive approaches to resistance partitioning found that partitioning estimates are highly sensitive to the order in which components are calculated and that such approaches inflate the values of difficult‐to‐measure components that are calculated by subtraction from measured components. This effect is especially significant where interactions between roughness features create synergistic increases in resistance such that total resistance measured for combinations of resistance components greatly exceeds the sum of those components measured separately. LWD contributes large proportions of total resistance by creating form drag on individual pieces and by increasing the spill resistance effect of steps. The combined effect of LWD and spill over steps was found to dominate total resistance, whereas grain roughness on step treads was a small component of total resistance. The relative contributions of grain, spill, and woody debris resistance were strongly influenced by discharge and to a lesser extent by LWD density. Grain resistance values based on published formulas and debris resistance values calculated using a cylinder drag approach typically underestimated analogous flume‐derived values, further illustrating sources of error in partitioning methods and the importance of accounting for interaction effects between resistance components.

Flow resistance dynamics in step-pool channels: 2. Partitioning between grain, spill, and woody debris resistance

NASA Astrophysics Data System (ADS)

Wilcox, Andrew C.; Nelson, Jonathan M.; Wohl, Ellen E.

2006-05-01

In step-pool stream channels, flow resistance is created primarily by bed sediments, spill over step-pool bed forms, and large woody debris (LWD). In order to measure resistance partitioning between grains, steps, and LWD in step-pool channels we completed laboratory flume runs in which total resistance was measured with and without grains and steps, with various LWD configurations, and at multiple slopes and discharges. Tests of additive approaches to resistance partitioning found that partitioning estimates are highly sensitive to the order in which components are calculated and that such approaches inflate the values of difficult-to-measure components that are calculated by subtraction from measured components. This effect is especially significant where interactions between roughness features create synergistic increases in resistance such that total resistance measured for combinations of resistance components greatly exceeds the sum of those components measured separately. LWD contributes large proportions of total resistance by creating form drag on individual pieces and by increasing the spill resistance effect of steps. The combined effect of LWD and spill over steps was found to dominate total resistance, whereas grain roughness on step treads was a small component of total resistance. The relative contributions of grain, spill, and woody debris resistance were strongly influenced by discharge and to a lesser extent by LWD density. Grain resistance values based on published formulas and debris resistance values calculated using a cylinder drag approach typically underestimated analogous flume-derived values, further illustrating sources of error in partitioning methods and the importance of accounting for interaction effects between resistance components.

Distribution of tetracycline resistance genes in anaerobic treatment of waste sludge: The role of pH in regulating tetracycline resistant bacteria and horizontal gene transfer.

PubMed

Huang, Haining; Chen, Yinguang; Zheng, Xiong; Su, Yinglong; Wan, Rui; Yang, Shouye

2016-10-01

Although pH value has been widely regarded as an important factor that affects resource recovery of waste sludge, the potential influence of diverse pHs on the distribution of tetracycline resistance genes (TRGs) during sludge anaerobic treatment is largely unknown. Here we reported that in the range of pH 4-10, 0.58-1.18 log unit increase of target TRGs was observed at pH 4, compared with that at pH 7, while 0.70-1.31 log unit further removal were obtained at pH 10. Mechanism study revealed that varied pHs not only altered the community structures of tetracycline resistant bacteria (TRB), but also changed their relative abundances, benefitting the propagation (acidic pHs) or attenuation (alkaline pHs) of TRB. Further investigation indicated that the amount and gene-possessing abilities of key genetic vectors for horizontal TRGs transfer were greatly promoted at acidic pHs but restricted under alkaline conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chemical composition and antibacterial activities of Illicium verum against antibiotic-resistant pathogens.

PubMed

Yang, Jyh-Ferng; Yang, Cheng-Hong; Chang, Hsueh-Wei; Yang, Cheng-San; Wang, Shao-Ming; Hsieh, Ming-Che; Chuang, Li-Yeh

2010-10-01

In recent years, human pathogenic microorganisms have developed multiple drug resistance and caused serious nosocomial infections. In this study, we identified four new antimicrobial compounds from the Chinese herbal medicine Illicium verum and assessed their antibacterial efficacies. The supercritical CO₂ and ethanol extracts of Illicium verum showed substantial antibacterial activity against 67 clinical drug-resistant isolates, including 27 Acinetobacter baumannii, 20 Pseudomonas aeruginosa, and 20 methicillin-resistant Staphylococcus aureus. The diethyl ether (EE) fraction obtained from partition extraction and supercritical CO₂ extracts revealed an antibacterial activity with a minimum inhibitory concentration value of 0.15-0.70 mg/mL and 0.11 mg/mL, respectively. The EE fraction of I. verum showed synergetic effects with some commercial antibiotics. The antimicrobial mechanism was investigated with killing curves and scanning electron microscopy observation. The chemical components of the extracts were analyzed by spectrophotometry; (E)-anethole, anisyl acetone, anisyl alcohol, and anisyl aldehyde exhibited antibacterial activity against different clinical isolates. These extracts from I. verum can be further developed into antibiotic medicines due to their proven antibacterial activity.

Effect of Processing Conditions on Fracture Resistance and Cohesive Laws of Binderfree All-Cellulose Composites

NASA Astrophysics Data System (ADS)

Goutianos, S.; Arévalo, R.; Sørensen, B. F.; Peijs, T.

2014-12-01

The fracture properties of all-cellulose composites without matrix were studied using Double Cantilever Beam (DCB) sandwich specimens loaded with pure monotonically increasing bending moments, which give stable crack growth. The experiments were conducted in an environmental scanning electron microscope to a) perform accurate measurements of both the fracture energy for crack initiation and the fracture resistance and b) observe the microscale failure mechanisms especially in the the wake of the crack tip. Since the mechanical behaviour of the all-cellulose composites was non-linear, a general method was first developed to obtain fracture resistance values from the DCB specimens taking into account the non-linear material response. The binderfree all-cellulose composites were prepared by a mechanical refinement process that allows the formation of intramolecular bonds between the cellulose molecules during the drying process. Defibrilation of the raw cellulose material is done in wet medium in a paper-like process. Panels with different refining time were tested and it was found than an increase in fibre fibrillation results in a lower fracture resistance.

Evaluation of the users value of salts against apple scab and powdery mildew for the integrated fruit production.

PubMed

Creemers, P; Van Laer, S; Van Mechelen, A; Vorstermans, B; Hauke, K

2007-01-01

As new fungicides are mainly unisite action fungicides, the problem of fungicide resistance development is becoming more important every year. Combining chemical fungicides, which is the best anti-resistance strategy, is not always possible or recommended in the case when the number of available chemical fungicides are limited or a reduction in fungicide use is asked for. Therefore the use of salts as an anti-resistance strategy was looked upon. The salts evaluated were K(HCO3), KH2PO3, KHPO4 and K2SiO3. When using these salts as an anti-resistance strategy the efficacy obtained when spraying the compounds alone was often to low to be used in rotation with chemical fungicides. Only with K(HCO3)2 a good efficacy can be observed in some years. The variation in efficacy with K(HCO3)2 observed is higher for powdery mildew. Chitosan was also included in the trials against powdery mildew, however chitosan had no effect on the infestation.

Geophysical data integration and conditional uncertainty analysis on hydraulic conductivity estimation

USGS Publications Warehouse

Rahman, A.; Tsai, F.T.-C.; White, C.D.; Carlson, D.A.; Willson, C.S.

2007-01-01

Integration of various geophysical data is essential to better understand aquifer heterogeneity. However, data integration is challenging because there are different levels of support between primary and secondary data needed to be correlated in various ways. This study proposes a geostatistical method to integrate the hydraulic conductivity measurements and electrical resistivity data to better estimate the hydraulic conductivity (K) distribution. The K measurements are obtained from the pumping tests and represent the primary data (hard data). The borehole electrical resistivity data from electrical logs are regarded as the secondary data (soft data). The electrical resistivity data is used to infer hydraulic conductivity values through the Archie law and Kozeny-Carman equation. A pseudo cross-semivariogram is developed to cope with the resistivity data non-collocation. Uncertainty in the auto-semivariograms and pseudo cross-semivariogram is quantified. The methodology is demonstrated by a real-world case study where the hydraulic conductivity is estimated in the Upper Chicot aquifer of Southwestern Louisiana. The groundwater responses by the cokriging and cosimulation of hydraulic conductivity are compared using analysis of variance (ANOVA). ?? 2007 ASCE.

Researches upon the cavitation erosion behaviour of austenite steels

NASA Astrophysics Data System (ADS)

Bordeasu, I.; Popoviciu, M. O.; Mitelea, I.; Salcianu, L. C.; Bordeasu, D.; Duma, S. T.; Iosif, A.

2016-02-01

Paper analyzes the cavitation erosion behavior of two stainless steels with 100% austenitic structure but differing by the chemical composition and the values of mechanical properties. The research is based on the MDE(t) and MDER(t) characteristic curves. We studied supplementary the aspect of the eroded areas by other to different means: observations with performing optical microscopes and roughness measurements. The tests were done in the T2 vibratory facility in the Cavitation Laboratory of the Timisoara Polytechnic University. The principal purpose of the study is the identification of the elements influencing significantly the cavitation erosion resistance. It was established the effect of the principal chemical components (determining the proportion of the structural components in conformity the Schaffler diagram) upon the cavitation erosion resistance. The results of the researches present the influence of the proportion of unstable austenite upon cavitation erosion resistance. The stainless steel with the great proportion of unstable austenite has the best behavior. The obtained conclusion are important for the metallurgists which realizes the stainless steels used for manufacturing the runners of hydraulic machineries (turbines and pumps) with increased resistance to cavitation attack.

Quantum transport in graphene Hall bars: Effects of side gates

NASA Astrophysics Data System (ADS)

Petrović, M. D.; Peeters, F. M.

2017-05-01

Quantum electron transport in side-gated graphene Hall bars is investigated in the presence of quantizing external magnetic fields. The asymmetric potential of four side-gates distorts the otherwise flat bands of the relativistic Landau levels, and creates new propagating states in the Landau spectrum (i.e. snake states). The existence of these new states leads to an interesting modification of the bend and Hall resistances, with new quantizing plateaus appearing in close proximity of the Landau levels. The electron guiding in this system can be understood by studying the current density profiles of the incoming and outgoing modes. From the fact that guided electrons fully transmit without any backscattering (similarly to edge states), we are able to analytically predict the values of the quantized resistances, and they match the resistance data we obtain with our numerical (tight-binding) method. These insights in the electron guiding will be useful in predicting the resistances for other side-gate configurations, and possibly in other system geometries, as long as there is no backscattering of the guided states.

Effects of borehole design on complex electrical resistivity measurements: laboratory validation and numerical experiments

NASA Astrophysics Data System (ADS)

Treichel, A.; Huisman, J. A.; Zhao, Y.; Zimmermann, E.; Esser, O.; Kemna, A.; Vereecken, H.

2012-12-01

Geophysical measurements within a borehole are typically affected by the presence of the borehole. The focus of the current study is to quantify the effect of borehole design on broadband electrical impedance tomography (EIT) measurements within boreholes. Previous studies have shown that effects on the real part of the electrical resistivity are largest for boreholes with large diameters and for materials with a large formation factor. However, these studies have not considered the effect of the well casing and the filter gravel on the measurement of the real part of the electrical resistivity. In addition, the effect of borehole design on the imaginary part of the electrical resistivity has not been investigated yet. Therefore, the aim of this study is to investigate the effect of borehole design on the complex electrical resistivity using laboratory measurements and numerical simulations. In order to do so, we developed a high resolution two dimensional axisymmetric finite element model (FE) that enables us to simulate the effects of several key borehole design parameters (e.g. borehole diameter, thickness of PVC well casing) on the measurement process. For the material surrounding the borehole, realistic values for complex resistivity were obtained from a database of laboratory measurements of complex resistivity from the test site Krauthausen (Germany). The slotted PVC well casing is represented by an effective resistivity calculated from the water-filled slot volume and the PVC volume. Measurements with and without PVC well casing were made with a four-electrode EIT logging tool in a water-filled rain barrel. The initial comparison for the case that the logging tool was inserted in the PVC well casing showed a considerable mismatch between measured and modeled values. It was required to consider a complete electrode model instead of point electrodes to remove this mismatch. This validated model was used to investigate in detail how complex resistivity measurements with different electrode configurations are affected by borehole design. Finally, the plausibility of our results was verified by comparing the simulation results with borehole EIT measurements made at the test site Krauthausen.

A case study of liquefaction risk analysis based on the thickness and depth of the liquefaction layer using CPT and electric resistivity data in the Hinode area, Itako City, Ibaraki Prefecture, Japan

NASA Astrophysics Data System (ADS)

Jinguuji, Motoharu; Toprak, Selcuk

2017-12-01

The Hinode area of Itako City in Ibaraki Prefecture, Japan, suffered some of the most severe liquefaction damage of any areas in the Great Eastern Japan Earthquake in 2011. This liquefaction damage has been investigated by Itako City, as well as by universities and research institutes in Japan. The National Institute of Advanced Industrial Science and Technology (AIST) has carried out numerous investigations along the Tone River, and in particular, intensive surveys were done in the Hinode area. We have conducted a risk analysis based on the thickness and depth of the liquefaction layer measured using cone penetration testing (CPT) data and electric resistivity data obtained in the Hinode area. The distribution of the risk estimated from CPT at 143 points, and that obtained from analysis of the resistivity survey data, agreed with the distribution of actual damage. We also carried out conventional risk analyses method using the liquefaction resistance factor (FL) and liquefaction potential index (PL) methods with CPT data. The results show high PL values over the entire area, but their distribution did not agree well with actual damage in some parts of the study area. Because the analysis of the thickness and depth of the liquefaction layer, using geophysical prospecting methods, can cover a widespread area, this method will be very useful in investigating liquefaction risk, especially for gas and water pipelines.

A 3D Resistivity Model of the Pyramid of La Luna (Teotihuacan, Mexico) Subsoil by Employing Non-Conventional ERT Arrays

NASA Astrophysics Data System (ADS)

Chavez, R. E.; Tejero, A.; Cifuentes, G.; Garcia-Serrano, A.; Argote-Espino, D. L.; HernaNdez-Quintero, J. E.; Ortega, V.

2017-12-01

The Pyramid of La Luna is found within the archaeological site of Teotihuacan, located to the NE of Mexico City. This pre-Hispanic city was developed between 250 AD and 450 AD, with a population of 100,000 people. The most important edifices are the pyramids of El Sol and La Luna. The pyramid of El Sol is one of the largest pre-Hispanic structures found nowadays in Mexico (a square basement of approximately 200m X 225 m). The pyramid of La Luna (with a base of 140m X 150m), smaller in size is located towards the northern portion of this ancient city. At its front, a big plaza is found surrounded by pyramids of different ages. Previous archaeological studies carried out within the plaza, discovered small shallow pipes for water discharge. Then, it is possible to find deeper structures within the Square. A geophysical work was carried out in the Plaza of La Luna employing the ERT-3D to build a 3D resistivity model. Four ERT profiles were deployed in the area in the E-W direction, with a length of 80 m each; electrodes were inserted 3 m apart. A roll-along technique was employed to obtain a 3D view of the plaza subsoil. Gradient (G), Equatorial (Eq), and Minimum Coupling (MC) arrays were applied. A total of 2,600 apparent resistivity observations were acquired. Also, the pyramid was surrounded with 105 electrodes to illuminate this structure subsoil, employing the 'L' and 'Corner' arrays and the already mentioned settings. Electrodes were separated 5 m for the E and N sides, and 6 m for the W and S sides, topographic correction was added to the interpretation. 7,200 apparent resistivity values were obtained. Processing of the data included noise filtering, real electrode position and removing of spikes. Finally, the data were inverted to compute a 3D resistivity distribution of the subsoil. Preliminary results obtained indicate the presence of high resistivity anomalies probably associated to infill or archaeological features. However, an interesting resistivity signature was determined at 8m deep, which possesses a SW-NE direction and apparently ends beneath the NE portion of the Pyramid of La Luna. Beneath the pyramid's center, the resistivity model interpreted depicts an important resistivity anomaly (about 350 Ohm-m and 10 m in diameter), which may indicate the presence of a cavity(?).

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

NASA Technical Reports Server (NTRS)

Reyes, A. L.; Campbell, J. E.

1976-01-01

The heat resistance of Bacillus subtilis var. niger was measured from 85 to 125 C using moisture levels of % RH or = 0.001 to 100. Curves are presented which characterize thermal destruction using thermal death times defined as F values at a given combination of three moisture and temperature conditions. The times required at 100 C for reductions of 99.99% of the initial population were estimated for the three moisture conditions. The linear model (from which estimates of D are obtained) was satisfactory for estimating thermal death times (% RH or = 0.07) in the plate count range. Estimates based on observed thermal death times and D values for % RH = 100 diverged so that D values generally gave a more conservative estimate over the temperature range 90 to 125 C. Estimates of Z sub F and Z sub L ranged from 32.1 to 58.3 C for % RH of or = 0.07 and 100. A Z sub D = 30.0 was obtained for data observed at % RH or = 0.07.

Room temperature current-voltage (I-V) characteristics of Ag/InGaN/n-Si Schottky barrier diode

NASA Astrophysics Data System (ADS)

Erdoğan, Erman; Kundakçı, Mutlu

2017-02-01

Metal-semiconductors (MSs) or Schottky barrier diodes (SBDs) have a significant potential in the integrated device technology. In the present paper, electrical characterization of Ag/InGaN/n-Si Schottky diode have been systematically carried out by simple Thermionic method (TE) and Norde function based on the I-V characteristics. Ag ohmic and schottky contacts are deposited on InGaN/n-Si film by thermal evaporation technique under a vacuum pressure of 1×10-5 mbar. Ideality factor, barrier height and series resistance values of this diode are determined from I-V curve. These parameters are calculated by TE and Norde methods and findings are given in a comparetive manner. The results show the consistency for both method and also good agreement with other results obtained in the literature. The value of ideality factor and barrier height have been determined to be 2.84 and 0.78 eV at room temperature using simple TE method. The value of barrier height obtained with Norde method is calculated as 0.79 eV.

An experimental method to determine the resistance of a vertically aligned carbon nanotube forest in contact with a conductive layer

NASA Astrophysics Data System (ADS)

Vo, T. T.; Poulain, C.; Dijon, J.; Fournier, A.; Chevalier, N.; Mariolle, D.

2012-08-01

High density vertically aligned carbon nanotube (VACNT) forests are considered as a promising conductive material for many applications (interconnects in microelectronics or contact material layer in sliding contact applications). It is thus crucial to characterize the electrical resistance of these forests, especially in contact with the inherent top/bottom conductive substrates. This paper aims to develop an original method to determine the contribution of the different terms in this electrical resistance, which is measured with a tipless atomic force microscope used in high accuracy "force mode." VACNT stacks with different heights on AlCu substrate with or without Au/Pd top coating are studied. The electrical contact area between the probe tip and the forest is considered to be equivalent to the classical electrical contact area between a tip and a rough surface. With this assumption, the scattering resistance of a mono-wall CNT is 14.6 kΩ μm-1, the top/bottom contact resistance is, respectively, 265 kΩ/385 kΩ. The bottom resistance divided in half is obtained by an interface substrate/CNT catalyst treatment. The same assumption leads to an effective compressive modulus of 175 MPa. These results are consistent with the values published by other authors. The proposed method is effective to optimise the CNT interface contact resistance before integration in a more complex functional structure.

The summit part of Mount Etna revealed by High Resolution DC Electrical Resistivity Tomography coupled with complementary geophysical and soil gas techniques

NASA Astrophysics Data System (ADS)

Finizola, Anthony; Ricci, Tullio; Antoine, Raphael; Delcher, Eric; Peltier, Aline; Bernard, Julien; Brothelande, Elodie; Fargier, Yannick; Fauchard, Cyrille; Foucart, Brice; Gailler, Lydie; Gusset, Rachel; Lazarte, Ivonne; Martin, Erwan; Mézon, Cécile; Portal, Angélie; Poret, Matthieu; Rossi, Matteo

2016-04-01

In the framework of the EC FP7 project "MEDiterranean SUpersite Volcanoes", one profile coupling DC electrical resistivity tomography (Pole-Dipole configuration with a remote electrode located between 8-10 km from the middle of the different acquisitions, 64 electrodes and 40 m spacing between the electrodes), self-potential, soil CO2 degassing, Radon measurements and sub-surface (30cm depth) temperature have been performed between June 25th and July 13th 2015. This profile, NE-SW direction, crossed the summit part of Mount Etna. A total 5720m of profile was performed, with a roll along protocol of 1/4 of the dispositive, for each new acquisitions. A total of 6 acquisitions was made to complete the entire profile. For the first time in the world, a multi-electrodes DC ERT profile, of high resolution (40 m of spacing between the electrodes) reached, thanks to a pole-dipole configuration, 900m for the depth of investigation. The ERT profile clearly evidences the hydrothermal system of Mount Etna: the lowest resistivity values are associated with a large scale positive self-potential anomaly, and smaller wavelength anomalies for temperature, CO2 concentration and Radon, in the area where the electrical conductor reach the surface. Structural discontinuities such as the Elliptic crater, was clearly evidenced by a sharp decrease of the self-potential values in the inner part of this crater. The striking result of this profile is the presence of a resistive body located just below the NE crater. This structure displays the highest degassing values of the entire profile. We interpret this resistive body as a consequence of the thermic over-heated plume rising from the top of the shallow feeding system. Indeed, above several hundred of degrees Celsuis, it is impossible to consider rain water infiltration and the presence of a wet hydrothermal system. The consequence would be therefore to obtain this resistive body, centred on the area of main heat transfer. Above this resistive body, we clearly note a preferential hydrothermal fluid flow, associated with maximum of self-potential anomaly, temperature and radon, and reaching the surface on the highest elevation area along the profile.

Evaluation of fouling in nanofiltration for desalination using a resistance-in-series model and optical coherence tomography.

PubMed

Park, Jongkwan; Lee, Sungyun; You, Jeongyeop; Park, Sanghun; Ahn, Yujin; Jung, Woonggyu; Cho, Kyung Hwa

2018-06-12

Resistance-in-series models have been applied to investigate fouling behavior. However, it is difficult to model the influence of morphology on fouling behavior because resistance is indirectly calculated from the water flux and transmembrane pressure. In this study, optical coherence tomography (OCT) was applied to evaluate the resistance of the fouling layer based on fouling morphology. Sodium alginate, humic acid, and bovine serum albumin (BSA) with high salts concentrations (conductivity: 23 mS/cm) were used as model foulants. At the same total fouling resistance, BSA showed the highest cake layer thickness (BSA (114.5 μm) > humic acid (53.5 μm) > sodium alginate (20.0 μm)). However, a different order was found for the cake layer resistance (BSA > sodium alginate > humic acid). This indicates that fouling thickness is not correlated with cake layer resistance. According to the Carman-Kozeny equation, fouling layer porosity decreased in the following order: humic acid (0.30) > BSA (0.21) > sodium alginate (0.20). In addition, we provided a specific value that was calculated using the ratio between the fouling thickness and cake layer resistance. The results show that alginic acid induced a stronger cake layer resistance, despite its thin fouling layer, whereas BSA showed a relatively low potential for inducing cake layer resistance. The results obtained in this study could be used for estimating and predicting fouling behavior. Copyright © 2018 Elsevier B.V. All rights reserved.

Segment-specific resistivity improves body fluid volume estimates from bioimpedance spectroscopy in hemodialysis patients.

PubMed

Zhu, F; Kuhlmann, M K; Kaysen, G A; Sarkar, S; Kaitwatcharachai, C; Khilnani, R; Stevens, L; Leonard, E F; Wang, J; Heymsfield, S; Levin, N W

2006-02-01

Discrepancies in body fluid estimates between segmental bioimpedance spectroscopy (SBIS) and gold-standard methods may be due to the use of a uniform value of tissue resistivity to compute extracellular fluid volume (ECV) and intracellular fluid volume (ICV). Discrepancies may also arise from the exclusion of fluid volumes of hands, feet, neck, and head from measurements due to electrode positions. The aim of this study was to define the specific resistivity of various body segments and to use those values for computation of ECV and ICV along with a correction for unmeasured fluid volumes. Twenty-nine maintenance hemodialysis patients (16 men) underwent body composition analysis including whole body MRI, whole body potassium (40K) content, deuterium, and sodium bromide dilution, and segmental and wrist-to-ankle bioimpedance spectroscopy, all performed on the same day before a hemodialysis. Segment-specific resistivity was determined from segmental fat-free mass (FFM; by MRI), hydration status of FFM (by deuterium and sodium bromide), tissue resistance (by SBIS), and segment length. Segmental FFM was higher and extracellular hydration of FFM was lower in men compared with women. Segment-specific resistivity values for arm, trunk, and leg all differed from the uniform resistivity used in traditional SBIS algorithms. Estimates for whole body ECV, ICV, and total body water from SBIS using segmental instead of uniform resistivity values and after adjustment for unmeasured fluid volumes of the body did not differ significantly from gold-standard measures. The uniform tissue resistivity values used in traditional SBIS algorithms result in underestimation of ECV, ICV, and total body water. Use of segmental resistivity values combined with adjustment for body volumes that are neglected by traditional SBIS technique significantly improves estimations of body fluid volume in hemodialysis patients.

Surveillance of Helicobacter pylori Antibiotic Susceptibility in Indonesia: Different Resistance Types among Regions and with Novel Genetic Mutations

PubMed Central

Miftahussurur, Muhammad; Syam, Ari Fahrial; Nusi, Iswan Abbas; Makmun, Dadang; Waskito, Langgeng Agung; Zein, Lukman Hakim; Akil, Fardah; Uwan, Willy Brodus; Simanjuntak, David; Wibawa, I Dewa Nyoman; Waleleng, Jimmy Bradley; Saudale, Alexander Michael Joseph; Yusuf, Fauzi; Mustika, Syifa; Adi, Pangestu; Maimunah, Ummi; Maulahela, Hasan; Rezkitha, Yudith Annisa Ayu; Subsomwong, Phawinee; Nasronudin; Rahardjo, Dadik; Suzuki, Rumiko; Akada, Junko; Yamaoka, Yoshio

2016-01-01

Information regarding Helicobacter pylori antibiotic resistance in Indonesia was previously inadequate. We assessed antibiotic susceptibility for H. pylori in Indonesia, and determined the association between virulence genes or genetic mutations and antibiotic resistance. We recruited 849 dyspeptic patients who underwent endoscopy in 11 cities in Indonesia. E-test was used to determine the minimum inhibitory concentration of five antibiotics. PCR-based sequencing assessed mutations in 23S rRNA, rdxA, gyrA, gyrB, and virulence genes. Next generation sequencing was used to obtain full-length sequences of 23S rRNA, infB, and rpl22. We cultured 77 strains and identified 9.1% with clarithromycin resistance. Low prevalence was also found for amoxicillin and tetracycline resistance (5.2% and 2.6%, respectively). In contrast, high resistance rates to metronidazole (46.7%) and levofloxacin (31.2%) were demonstrated. Strains isolated from Sumatera Island had significantly higher metronidazole resistance than those from other locations. Metronidazole resistant strains had highly distributed rdxA amino acid substitutions and the 23S rRNA A2143G mutation was associated with clarithromycin resistance (42.9%). However, one strain with the highest MIC value had a novel mutation in rpl22 without an A2143G mutation. Mutation at Asn-87 and/or Asp-91 of gyrA was associated with levofloxacin-resistance and was related to gyrB mutations. In conclusions, although this is a pilot study for a larger survey, our current data show that Indonesian strains had the high prevalence of metronidazole and levofloxacin resistance with low prevalence of clarithromycin, amoxicillin, and tetracycline resistance. Nevertheless, clarithromycin- or metronidazole-based triple therapy should be administered with caution in some regions of Indonesia. PMID:27906990

Surveillance of Helicobacter pylori Antibiotic Susceptibility in Indonesia: Different Resistance Types among Regions and with Novel Genetic Mutations.

PubMed

Miftahussurur, Muhammad; Syam, Ari Fahrial; Nusi, Iswan Abbas; Makmun, Dadang; Waskito, Langgeng Agung; Zein, Lukman Hakim; Akil, Fardah; Uwan, Willy Brodus; Simanjuntak, David; Wibawa, I Dewa Nyoman; Waleleng, Jimmy Bradley; Saudale, Alexander Michael Joseph; Yusuf, Fauzi; Mustika, Syifa; Adi, Pangestu; Maimunah, Ummi; Maulahela, Hasan; Rezkitha, Yudith Annisa Ayu; Subsomwong, Phawinee; Nasronudin; Rahardjo, Dadik; Suzuki, Rumiko; Akada, Junko; Yamaoka, Yoshio

2016-01-01

Information regarding Helicobacter pylori antibiotic resistance in Indonesia was previously inadequate. We assessed antibiotic susceptibility for H. pylori in Indonesia, and determined the association between virulence genes or genetic mutations and antibiotic resistance. We recruited 849 dyspeptic patients who underwent endoscopy in 11 cities in Indonesia. E-test was used to determine the minimum inhibitory concentration of five antibiotics. PCR-based sequencing assessed mutations in 23S rRNA, rdxA, gyrA, gyrB, and virulence genes. Next generation sequencing was used to obtain full-length sequences of 23S rRNA, infB, and rpl22. We cultured 77 strains and identified 9.1% with clarithromycin resistance. Low prevalence was also found for amoxicillin and tetracycline resistance (5.2% and 2.6%, respectively). In contrast, high resistance rates to metronidazole (46.7%) and levofloxacin (31.2%) were demonstrated. Strains isolated from Sumatera Island had significantly higher metronidazole resistance than those from other locations. Metronidazole resistant strains had highly distributed rdxA amino acid substitutions and the 23S rRNA A2143G mutation was associated with clarithromycin resistance (42.9%). However, one strain with the highest MIC value had a novel mutation in rpl22 without an A2143G mutation. Mutation at Asn-87 and/or Asp-91 of gyrA was associated with levofloxacin-resistance and was related to gyrB mutations. In conclusions, although this is a pilot study for a larger survey, our current data show that Indonesian strains had the high prevalence of metronidazole and levofloxacin resistance with low prevalence of clarithromycin, amoxicillin, and tetracycline resistance. Nevertheless, clarithromycin- or metronidazole-based triple therapy should be administered with caution in some regions of Indonesia.

Assessment of peak power and short-term work capacity.

PubMed

MacIntosh, Brian R; Rishaug, Peter; Svedahl, Krista

2003-02-01

The purpose of this study was to evaluate conditions for conducting a 30 s Wingate test such as load selection, and the method of starting the test (stationary or flying start). Nine male and four female athletes volunteered to be tested on four laboratory visits. Tests were performed on a modified Monark cycle ergometer (Varberg, Sweden) equipped with force transducers on the friction belt and an optical encoder for velocity measurement. Power was calculated with the moment of inertia (I) of the flywheel taken into consideration. One laboratory visit was used to determine individualized optimal resistance conditions. The other three visits were for performance of one of three Wingate tests: a flying start with 0.834 N x kg(-1) [85 g x kg(-1) body weight (BW)] resistance (FLY-0.8); a stationary start with 0.834 N x kg(-1) BW resistance (ST-0.8), or a stationary start with optimal resistance (ST-OPT). FLY-0.8 gave a lower (P<0.05) value for short-term work capacity [19,986 (827) J] than either ST-OPT [23,014 (1,167) J] or ST-0.8 [22,321 (1075) J]. Peak power output per pedal revolution was lower ( P<0.005) for FLY-0.8 [833 (40) W] than for either ST-0.8 [974 (57) W] or ST-OPT [989 (61) W]. The results of this study demonstrate that higher values for peak power and short-term work capacity are obtained with a test from a stationary start. It is apparently not necessary to use an individualized optimal resistance when I is considered in a Wingate test initiated from a standstill.

Role of the Egami score to predict immunoglobulin resistance in Kawasaki disease among a Western Mediterranean population.

PubMed

Sánchez-Manubens, Judith; Antón, Jordi; Bou, Rosa; Iglesias, Estíbaliz; Calzada-Hernandez, Joan; Borlan, Sergi; Gimenez-Roca, Clara; Rivera, Josefa

2016-07-01

Kawasaki disease is an acute self-limited systemic vasculitis common in childhood. Intravenous immunoglobulin (IVIG) is an effective treatment, and it reduces the incidence of cardiac complications. Egami score has been validated to identify IVIG non-responder patients in Japanese population, and it has shown high sensitivity and specificity to identify these non-responder patients. Although its effectiveness in Japan, Egami score has shown to be ineffective in non-Japanese populations. The aim of this study was to apply the Egami score in a Western Mediterranean population in Catalonia (Spain). Observational population-based study that includes patients from all Pediatric Units in 33 Catalan hospitals, both public and private management, between January 2004 and March 2014. Sensitivity and specificity for the Egami score was calculated, and a logistic regression analysis of predictors of overall response to IVIG was also developed. Predicting IVIG resistance with a cutoff for Egami score ≥3 obtained 26 % sensitivity and 82 % specificity. Negative predictive value was 85 % and positive predictive value 22 %. This low sensitivity implies that three out of four non-responders will not be identified by the Egami score. Besides, logistic regression models did not found significance for the use of the Egami score to predict IVIG resistance in Catalan population although having an area under the ROC curve of 0.618 (IC 95 % 0.538-0.698, p < 0.001). Although regression models found an area under the ROC curve >0.5 to predict IVIG resistance, the low sensitivity excludes the Egami score as a useful tool to predict IVIG resistance in Catalan population.

Insecticide Resistance in Eggs and First Instars of the Bed Bug, Cimex lectularius (Hemiptera: Cimicidae).

PubMed

Campbell, Brittany E; Miller, Dini M

2015-01-15

Two strains of the common bed bug, Cimex lectularius L., eggs and first instars collected from pyrethroid-resistant adults were evaluated for insecticide resistance and compared to a susceptible strain. Dose-response bioassays were conducted using two insecticide formulations (Temprid: imidacloprid/β-cyfluthrin, and Transport: acetamiprid/ bifenthrin). The lethal concentration (LC50) for the two resistant egg strains exposed to imidacloprid/β-cyfluthrin ranged from 3 to 5-fold higher than susceptible strain eggs. Resistant strain eggs dipped into formulations of acetamiprid/bifenthrin had LC50 values which were significantly greater (39 to 1,080-fold) than susceptible strain eggs. Similar to eggs, resistant strain first instars exposed to residual applications of imidacloprid/β-cyfluthrin had LC50 values ranging from 121 to 493-fold greater than susceptible strain first instars. When resistant strain first instars were treated with acetamiprid/bifenthrin, they had LC50 values that were 99 to >1,900-fold greater than susceptible strain first instars. To determine differences between egg and first instar resistance, stage resistance ratios (SRR) were compared between the two stages. There was little difference between the egg and first instar stages, indicated by small SRR values ranging from 1.1 to 10.0. This study suggests that insecticide resistance is expressed early during bed bug development.

Insecticide Resistance in Eggs and First Instars of the Bed Bug, Cimex lectularius (Hemiptera: Cimicidae)

PubMed Central

Campbell, Brittany E.; Miller, Dini M.

2015-01-01

Two strains of the common bed bug, Cimex lectularius L., eggs and first instars collected from pyrethroid-resistant adults were evaluated for insecticide resistance and compared to a susceptible strain. Dose-response bioassays were conducted using two insecticide formulations (Temprid: imidacloprid/β-cyfluthrin, and Transport: acetamiprid/bifenthrin). The lethal concentration (LC50) for the two resistant egg strains exposed to imidacloprid/β-cyfluthrin ranged from 3 to 5-fold higher than susceptible strain eggs. Resistant strain eggs dipped into formulations of acetamiprid/bifenthrin had LC50 values which were significantly greater (39 to 1,080-fold) than susceptible strain eggs. Similar to eggs, resistant strain first instars exposed to residual applications of imidacloprid/β-cyfluthrin had LC50 values ranging from 121 to 493-fold greater than susceptible strain first instars. When resistant strain first instars were treated with acetamiprid/bifenthrin, they had LC50 values that were 99 to >1,900-fold greater than susceptible strain first instars. To determine differences between egg and first instar resistance, stage resistance ratios (SRR) were compared between the two stages. There was little difference between the egg and first instar stages, indicated by small SRR values ranging from 1.1 to 10.0. This study suggests that insecticide resistance is expressed early during bed bug development. PMID:26463070

Assessment of insulin resistance in Chinese PCOS patients with normal glucose tolerance.

PubMed

Gao, Jing; Zhou, Li; Hong, Jie; Chen, Chen

2017-11-01

The study aimed to investigate insulin resistance (IR) status in polycystic ovary syndrome (PCOS) women with normal glucose tolerance (NGT), and further to evaluate feasible diagnostic method for those patients. Three hundred and twenty-five PCOS women with NGT and ninety-five healthy age-matched controls were recruited with Rotterdam criterion and 75 g oral glucose tolerance test (OGTT). IR status was estimated following a glycemic and insulinemic OGTT (0, 30, 60, 120, and 180 min). A modified HOMA-IR formula was applied to each time-course value of glycemia and insulinemia. The predictive performance of each IR index was analyzed with the use of ROC curves. Compared with healthy controls, both non-obese and obese PCOS patients with NGT had a higher BMI, serum glucose, insulin value (p < .05). The best predictive index of IR in non-obese PCOS-NGT was a HOMA-M30 value of 20.36 or more (AUC: 0.753). In obese PCOS-NGT population, the best predictive performance was obtained by a HOMA-M60 value of 32.17 or more (AUC: 0.868). IR was common in Chinese PCOS women with NGT, and the early assessment of IR should be heeded. We recommended HOMA-M30 (Cutoff: 20.36) and HOMA-M60 (Cutoff: 32.17) as the best predictive parameters for non-obese and obese PCOS-NGT patients, respectively.

Temperature dependent current-voltage characteristics of Au/n-Si Schottky barrier diodes and the effect of transition metal oxides as an interface layer

NASA Astrophysics Data System (ADS)

Mahato, Somnath; Puigdollers, Joaquim

2018-02-01

Temperature dependent current-voltage (I‒V) characteristics of Au/n-type silicon (n-Si) Schottky barrier diodes have been investigated. Three transition metal oxides (TMO) are used as an interface layer between gold and silicon. The basic Schottky diode parameters such as ideality factor (n), barrier height (ϕb 0) and series resistance (Rs) are calculated and successfully explained by the thermionic emission (TE) theory. It has been found that ideality factor decreased and barrier height increased with increased of temperature. The conventional Richardson plot of ln(I0/T2) vs. 1000/T is determined the activation energy (Ea) and Richardson constant (A*). Whereas value of 'A*' is much smaller than the known theoretical value of n-type Si. The temperature dependent I-V characteristics obtained the mean value of barrier height (ϕb 0 bar) and standard deviation (σs) from the linear plot of ϕap vs. 1000/T. From the modified Richardson plot of ln(I0/T2) ˗ (qσ)2/2(kT)2 vs. 1000/T gives Richardson constant and homogeneous barrier height of Schottky diodes. Main observation in this present work is the barrier height and ideality factor shows a considerable change but the series resistance value exhibits negligible change due to TMO as an interface layer.

Surface flow and heating distributions on a cylinder in near wake of Aeroassist Flight Experiment (AFE) configuration at incidence in Mach 10 Air

NASA Technical Reports Server (NTRS)

Wells, William L.

1990-01-01

Experimental heat transfer distributions and surface streamline directions are presented for a cylinder in the near wake of the Aeroassist Flight Experiment forebody configuration. Tests were conducted in air at a nominal free stream Mach number of 10, with post shock Reynolds numbers based on model base height of 6,450 to 50,770, and angles of attack of 5, 0, -5, and -10 degrees. Heat transfer data were obtained with thin film resistance gage and surface streamline directions by the oil flow technique. Comparisons between measured values and predicted values were made by using a Navier-Stokes computer code.

Dynamic characteristics of organic bulk-heterojunction solar cells

NASA Astrophysics Data System (ADS)

Babenko, S. D.; Balakai, A. A.; Moskvin, Yu. L.; Simbirtseva, G. V.; Troshin, P. A.

2010-12-01

Transient characteristics of organic bulk-heterojunction solar cells have been studied using pulsed laser probing. An analysis of the photoresponse waveforms of a typical solar cell measured by varying load resistance within broad range at different values of the bias voltage provided detailed information on the photocell parameters that characterize electron-transport properties of active layers. It is established that the charge carrier mobility is sufficient to ensure high values of the fill factor (˜0.6) in the obtained photocells. On approaching the no-load voltage, the differential capacitance of the photocell exhibits a sixfold increase as compared to the geometric capacitance. A possible mechanism of recombination losses in the active medium is proposed.

Experimental approach to the anion problem in DFT calculation of the partial charge transfer during adsorption at electrochemical interfaces

NASA Astrophysics Data System (ADS)

Marichev, V. A.

2005-08-01

In DFT calculation of the charge transfer (Δ N), anions pose a special problem since their electron affinities are unknown. There is no method for calculating reasonable values of the absolute electronegativity ( χA) and chemical hardness ( ηA) for ions from data of species themselves. We propose a new approach to the experimental measurement of χA at the condition: Δ N = 0 at which η values may be neglected and χA = χMe. Electrochemical parameters corresponding to this condition may be obtained by the contact electric resistance method during in situ investigation of anion adsorption in the particular system anion-metal.

Inappropriate Use of Homeostasis Model Assessment Cutoff Values for Diagnosing Insulin Resistance in Pediatric Studies.

PubMed

Fox, Carrie; Bernardino, Lourdes; Cochran, Jill; Essig, Mary; Bridges, Kristie Grove

2017-11-01

Assessing pediatric patients for insulin resistance is one way to identify those who are at a high risk of developing type 2 diabetes mellitus. The homoeostasis model assessment (HOMA) is a measure of insulin resistance based on fasting blood glucose and insulin levels. Although this measure is widely used in research, cutoff values for pediatric populations have not been established. To assess the validity of HOMA cutoff values used in pediatric studies published in peer-reviewed journals. Studies published from January 2010 to December 2015 were identified through MEDLINE. Initial screening of abstracts was done to select studies that were conducted in pediatric populations and used HOMA to assess insulin resistance. Subsequent full-text review narrowed the list to only those studies that used a specific HOMA score to diagnose insulin resistance. Each study was classified as using a predetermined fixed HOMA cutoff value or a cutoff that was a percentile specific to that population. For studies that used a predetermined cutoff value, the references cited to provide evidence in support of that cutoff were evaluated. In the 298 articles analyzed, 51 different HOMA cutoff values were used to classify patients as having insulin resistance. Two hundred fifty-five studies (85.6%) used a predetermined fixed cutoff value, but only 72 (28.2%) of those studies provided a reference that supported its use. One hundred ten studies (43%) that used a fixed cutoff either cited a study that did not mention HOMA or provided no reference at all. Tracing of citation history indicated that the most commonly used cutoff values were ultimately based on studies that did not validate their use for defining insulin resistance. Little evidence exists to support HOMA cutoff values commonly used to define insulin resistance in pediatric studies. These findings highlight the importance of validating study design elements when training medical students and novice investigators. Using available data to generate population ranges for HOMA would improve its clinical utility.

Stroke volume obtained by electrical interrogation of the brachial artery: transbrachial electrical bioimpedance velocimetry.

PubMed

Bernstein, Donald P; Henry, Isaac C; Banet, Mathew J; Dittrich, Teri

2012-04-01

The goal of this study is to measure left ventricular stroke volume (SV) from the brachial artery (BA) using electrical bioimpedance. Doppler-derived SV was used for comparison. Twenty-nine healthy adults were recruited for study. Doppler echocardiographic-derived SV was obtained from the product of distal left ventricular outflow tract cross-sectional area and systolic velocity integral. SV from the BA was obtained by transbrachial electrical bioimpedance velocimetry (TBEV). Application of a current field across the left brachium was effected by injection of a constant magnitude, high frequency, low amperage, alternating current. Therein, a static voltage (U(0)) and pulsatile voltage change (ΔU(t)) were measured and converted to their corresponding impedances, Z(0) and ΔZ(t). TBEV-derived SV was obtained by multiplying a square root value of the normalized, acceleration-based, peak first time derivative of ΔZ(t) by a volume conductor and systolic flow time. Inter-method agreement was determined by the Bland-Altman method. To assess the contribution of blood resistivity variations to ΔZ(t), BA diameters were measured at end-diastole and peak systolic expansion. Results indicate that since the BA demonstrates parabolic, laminar flow, with minimal diameter changes, blood resistivity variations are likely responsible for the derived impedance changes. Bland-Altman analysis shows that SV is obtainable by TBEV from healthy humans at rest. © 2012 Institute of Physics and Engineering in Medicine

Maximal violation of Clauser-Horne-Shimony-Holt inequality for four-level systems

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

Fu Libin; Max-Planck-Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden; Chen Jingling

2004-03-01

Clauser-Horne-Shimony-Holt inequality for bipartite systems of four dimensions is studied in detail by employing the unbiased eight-port beam splitters measurements. The uniform formulas for the maximum and minimum values of this inequality for such measurements are obtained. Based on these formulas, we show that an optimal nonmaximally entangled state is about 6% more resistant to noise than the maximally entangled one. We also give the optimal state and the optimal angles which are important for experimental realization.

Temperature Dependent Performance of Coplanar Waveguide (CPW) on Substrates of Various Materials

NASA Technical Reports Server (NTRS)

Taub, Susan R.; Young, Paul

1994-01-01

The attenuation (a) and effective dielectric constant (E(sub eff)) of Coplanar Waveguide (CPW) transmission lines on high-resistivity silicon and diamond substrates as a function of both temperature and frequency are presented. The technique used to obtain the values for a and E(sub eff) involves the use of a unique cryogenic probe station designed and built by NASA. Attenuation of gold CPW lines on diamond substrates is compared with that of superconducting CPW lines.

Applied potential tomography. A new noninvasive technique for measuring gastric emptying

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

Avill, R.; Mangnall, Y.F.; Bird, N.C.

1987-04-01

Applied potential tomography is a new, noninvasive technique that yields sequential images of the resistivity of gastric contents after subjects have ingested a liquid or semisolid meal. This study validates the technique as a means of measuring gastric emptying. Experiments in vitro showed an excellent correlation between measurements of resistivity and either the square of the radius of a glass rod or the volume of water in a spherical balloon when both were placed in an oval tank containing saline. Altering the lateral position of the rod in the tank did not alter the values obtained. Images of abdominal resistivitymore » were also directly correlated with the volume of air in a gastric balloon. Profiles of gastric emptying of liquid meals obtained using applied potential tomography were very similar to those obtained using scintigraphy or dye dilution techniques, provided that acid secretion was inhibited by cimetidine. Profiles of emptying of a mashed potato meal using applied potential tomography were also very similar to those obtained by scintigraphy. Measurements of the emptying of a liquid meal from the stomach were reproducible if acid secretion was inhibited by cimetidine. Thus, applied potential tomography is an accurate and reproducible method of measuring gastric emptying of liquids and particulate food. It is inexpensive, well tolerated, easy to use, and ideally suited for multiple studies in patients, even those who are pregnant.« less

Site characterization and evaluation of the stability of the Yesilyurt Landslide (Trabzon, NE Turkey) using back analysis method

NASA Astrophysics Data System (ADS)

Kul Yahşi, Bilgehan; Ersoy, Hakan

2018-06-01

The aim of this study was to determine the soil profile of the Yeşilyurt Landslide Area (NE Turkey) and to investigate the stability of the landslide area after the excavation planned by back analysis for support design. For these purposes, after the 1/1000 scaled engineering geological map was prepared, seismic refraction, electrical resistivity tomography and ground penetrating radar measurements were performed on different profiles to understand vertical and horizontal homogeneity of the landslide materials and undisturbed/disturbed soil samples were obtained from the test pits to determine the geotechnical properties of the soil. The results of the geophysical measurements showed that the landslide material was composed of two different soil zones. While the maximum thickness of the upper zone is 2.5, the thickness of the lower zone is about 5 m. The depth of dasidic rock mass is about 7 m. Residual cohesions of the soil samples obtained upper and lower zones were determined as 38 kPa and 44 kPa, and their residual friction angles were determined as 18° and 15° respectively. Unit weight values of the soil samples obtained from both zones were 16.9 kN m-3. The data obtained from laboratory tests showed that the landslide material is a uniform lithology. The geophysical measurements indicate that the wave velocity and resistivity values of these profiles differ from each other due to groundwater at a depth of 2.5 m. Limit equilibrium analysis were carried out with Slide v5.0 software using data obtained from the field measurements and laboratory tests to evaluate current and supported cases of the studied area. Because the safety factor of the slope obtained from the LE analyses is 0.99 and the studied soil environment is considered as unstable, the reliable and economical reinforcement was suggested using the retaining wall. The back-analysis method was evaluated to ensure the stability for a 1.5 safety factor and finally the lateral active forces for the retaining wall were calculated in the LE analysis as 718 kN and 1839 kN for without and with seismic load respectively.

Assessment of errors in static electrical impedance tomography with adjacent and trigonometric current patterns.

PubMed

Kolehmainen, V; Vauhkonen, M; Karjalainen, P A; Kaipio, J P

1997-11-01

In electrical impedance tomography (EIT), difference imaging is often preferred over static imaging. This is because of the many unknowns in the forward modelling which make it difficult to obtain reliable absolute resistivity estimates. However, static imaging and absolute resistivity values are needed in some potential applications of EIT. In this paper we demonstrate by simulation the effects of different error components that are included in the reconstruction of static EIT images. All simulations are carried out in two dimensions with the so-called complete electrode model. Errors that are considered are the modelling error in the boundary shape of an object, errors in the electrode sizes and localizations and errors in the contact impedances under the electrodes. Results using both adjacent and trigonometric current patterns are given.

Resistance to extinction of human evaluative conditioning using a between-subjects design.

PubMed

Baeyens, F; Díaz, E; Ruiz, G

2005-02-01

Two experiments were conducted to examine whether the resistance to extinction obtained in evaluative conditioning (EC) studies implies that EC is a qualitatively distinct form of classical conditioning (Baeyens, Eelen, & Crombez, 1995 a) or whether it is the result of an nonassociative artefact ( Field & Davey, 1997 , 1998 , 1999 ). Both experiments included between-subjects control groups in addition to standard within-subjects control conditions. In Experiment 1, only verbal ratings were measured in order to evaluate the effect of postacquisition CS-only exposures on EC whereas in Experiment 2, verbal ratings and postextinction priming effects were measured. The results showed that the EC effects are demonstrable in a between-subjects design and that the extinction procedure did not have any influence on the acquired evaluative value of CSs regardless of whether the verbal ratings or the priming effects were used as dependent variables. The present results provide evidence that EC is resistant to extinction and suggest an interpretation of EC as a qualitatively distinct form of associative learning.

Antifungal activity of synthetic antiseptics and natural compounds against Candida dubliniensis before and after in vitro fluconazole exposure.

PubMed

Reginato, Cássia Franco; Bandeira, Laíssa Arévalo; Zanette, Régis Adriel; Santurio, Janio Morais; Alves, Sydney Hartz; Danesi, Cristiane Cademartori

2017-01-01

This study evaluated the susceptibilities of oral candidiasis-derived Candida albicans, fluconazole-resistant (FR) Candida dubliniensis, and fluconazole-susceptible (FS) C. dubliniensis to synthetic antiseptics [chlorhexidine gluconate (CHX), cetylpyridinium chloride (CPC), and triclosan (TRC)] and natural compounds (carvacrol, eugenol and thymol). Susceptibility tests were performed based on the M27-A3 reference method. The fluconazole-resistant C. dubliniensis strains were obtained after prolonged in vitro exposure to increasing fluconazole concentrations. The geometric mean values for minimum inhibitory concentrations and minimum fungicidal concentrations were compared among the groups. Fluconazole-susceptible C. dubliniensis was more sensitive to CPC and TRC than FR C. dubliniensis and C. albicans were. However, eugenol and thymol were more active against FR C. dubliniensis. The fungicidal activities of CHX and TRC were similar for the three groups, and FR C. dubliniensis and C. albicans had similar sensitivities to CPC. The resistance of C. dubliniensis to fluconazole affects its sensitivity the synthetic antiseptics and natural compounds that were tested.

Microbial desalination cells packed with ion-exchange resin to enhance water desalination rate.

PubMed

Morel, Alexandre; Zuo, Kuichang; Xia, Xue; Wei, Jincheng; Luo, Xi; Liang, Peng; Huang, Xia

2012-08-01

A novel configuration of microbial desalination cell (MDC) packed with ion-exchange resin (R-MDC) was proposed to enhance water desalination rate. Compared with classic MDC (C-MDC), an obvious increase in desalination rate (DR) was obtained by R-MDC. With relatively low concentration (10-2 g/L NaCl) influents, the DR values of R-MDC were about 1.5-8 times those of C-MDC. Ion-exchange resins packed in the desalination chamber worked as conductor and thus counteracted the increase in ohmic resistance during treatment of low concentration salt water. Ohmic resistances of R-MDC stabilized at 3.0-4.7 Ω. By contrast, the ohmic resistances of C-MDC ranged from 5.5 to 12.7 Ω, which were 55-272% higher than those of R-MDC. Remarkable improvement in desalination rate helped improve charge efficiency for desalination in R-MDC. The results first showed the potential of R-MDC in the desalination of water with low salinity. Copyright © 2012 Elsevier Ltd. All rights reserved.

Extrinsic origins of the apparent relaxorlike behavior in CaCu3Ti4O12 ceramics at high temperatures: A cautionary tale

NASA Astrophysics Data System (ADS)

Li, Ming; Sinclair, Derek C.; West, Anthony R.

2011-04-01

Although the origins of the high effective permittivity observed in CaCu3Ti4O12 (CCTO) ceramics and single crystals at ˜100-400 K have been resolved, the relaxorlike temperature- and frequency-dependence of permittivity obtained from fixed frequency capacitance measurements at higher temperatures reported in the literature remains unexplained, especially as CCTO adopts a centrosymmetric cubic crystal structure in the range of ˜35-1273 K. Impedance spectroscopy studies reveal that this type of relaxorlike behavior is an artifact induced mainly by a nonohmic sample-electrode contact impedance. In addition, an instrument-related parasitic series inductance and resistance effect modifies the measured capacitance values as the sample resistance decreases with increasing temperature. This can lead to an underestimation of the sample capacitance and, in extreme cases, to so-called `negative capacitance.' Such a relaxorlike artifact and negative capacitance behavior are not unique to CCTO and may be expected in other leaky dielectrics whose resistance is low.

Can we use genetic and genomic approaches to identify candidate animals for targeted selective treatment.

PubMed

Laurenson, Yan C S M; Kyriazakis, Ilias; Bishop, Stephen C

2013-10-18

Estimated breeding values (EBV) for faecal egg count (FEC) and genetic markers for host resistance to nematodes may be used to identify resistant animals for selective breeding programmes. Similarly, targeted selective treatment (TST) requires the ability to identify the animals that will benefit most from anthelmintic treatment. A mathematical model was used to combine the concepts and evaluate the potential of using genetic-based methods to identify animals for a TST regime. EBVs obtained by genomic prediction were predicted to be the best determinant criterion for TST in terms of the impact on average empty body weight and average FEC, whereas pedigree-based EBVs for FEC were predicted to be marginally worse than using phenotypic FEC as a determinant criterion. Whilst each method has financial implications, if the identification of host resistance is incorporated into a wider genomic selection indices or selective breeding programmes, then genetic or genomic information may be plausibly included in TST regimes. Copyright © 2013 Elsevier B.V. All rights reserved.

Traction test of temporary dental cements

PubMed Central

Millan-Martínez, Diego; Fons-Font, Antonio; Agustín-Panadero, Rubén; Fernández-Estevan, Lucía

2017-01-01

Background Classic self-curing temporary cements obstruct the translucence of provisional restorations. New dual-cure esthetic temporary cements need investigation and comparison with classic cements to ensure that they are equally retentive and provide adequate translucence. The objective is to analyze by means of traction testing in a in vitro study the retention of five temporary cements. Material and Methods Ten molars were prepared and ten provisional resin restorations were fabricated using CAD-CAM technology (n=10). Five temporary cements were selected: self-curing temporary cements, Dycal (D), Temp Bond (TB), Temp Bond Non Eugenol (TBNE); dual-curing esthetic cements Temp Bond Clear (TBC) and Telio CS link (TE). Each sample underwent traction testing, both with thermocycling (190 cycles at 5-55º) and without thermocycling. Results TE and TBC obtained the highest traction resistance values. Thermocycling reduced the resistance of all cements except TBC. Conclusions The dual-cure esthetic cements tested provided optimum outcomes for bonding provisional restorations. Key words:Temporary dental cements, cements resistance. PMID:28469824

Growth and interface properties of Au Schottky contact on ZnO grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Asghar, M.; Mahmood, K.; Malik, Faisal; Hasan, M. A.

2013-06-01

In this paper, we have discussed the growth of ZnO by molecular beam epitaxy (MBE) and interface properties of Au Schottky contacts on grown sample. After the verification of structure and surface properties by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM), respectively, Au metal contact was fabricated by e-beam evaporation to study contact properties. The high value of ideality factor (2.15) and barrier height (0.61 eV) at room temperature obtained by current-voltage (I-V) characteristics suggested the presence of interface states between metal and semiconductor. To confirm this observation we carried out frequency dependent capacitance-voltage (C-V) and conductance-voltage (G-V) demonstrated that the capacitance of diode decreased with increasing frequency. The reason of this behavior is related with density of interface states, series resistance and image force lowering. The C-2-V plot drawn to calculate the carrier concentration and barrier height with values 1.4×1016 cm-3 and 0.92 eV respectively. Again, high value of barrier height obtained from C-V as compared to the value obtained from I-V measurements revealed the presence of interface states. The density of these interface states (Dit) was calculated by well known Hill-Coleman method. The calculated value of Dit at 1 MHz frequency was 2×1012 eV-1 cm-2. The plot between interface states and frequency was also drawn which demonstrated that density of interface states had inverse proportion with measuring frequency.

Development of MATLAB Scripts for the Calculation of Thermal Manikin Regional Resistance Values

DTIC Science & Technology

2016-01-01

CALCULATION OF THERMAL MANIKIN REGIONAL RESISTANCE VALUES DISCLAIMER The opinions or assertions contained herein are the private views of the...USARIEM TECHNICAL NOTE TN16-1 DEVELOPMENT OF MATLAB® SCRIPTS FOR THE CALCULATION OF THERMAL MANIKIN REGIONAL RESISTANCE VALUES...performed by thermal manikin and modeling personnel. Steps to operate the scripts as well as the underlying calculations are outlined in detail

Two-dimensional resistivity investigation along West Fork Trinity River, Naval Air Station-Joint Reserve Base, Carswell Field, Fort Worth, Texas, October 2004

USGS Publications Warehouse

Shah, Sachin D.; Stanton, Gregory P.

2006-01-01

Naval Air Station-Joint Reserve Base Carswell Field (NAS-JRB) at Fort Worth, Tex., constitutes a government-owned, contractor-operated facility that has been in operation since 1942. Contaminants, primarily volatile organic compounds and metals, have entered the ground-water-flow system through leakage from waste-disposal sites and manufacturing processes. Ground water flows from west to east toward the West Fork Trinity River. During October 2004, the U.S. Geological Survey conducted a two-dimensional (2D) resistivity investigation at a site along the West Fork Trinity River at the eastern boundary of NAS-JRB to characterize the distribution of subsurface resistivity. Five 2D resistivity profiles were collected, which ranged from 500 to 750 feet long and extended to a depth of 25 feet. The Goodland Limestone and the underlying Walnut Formation form a confining unit that underlies the alluvial aquifer. The top of this confining unit is the top of bedrock at NAS-JRB. The bedrock confining unit is the zone of interest because of the potential for contaminated ground water to enter the West Fork Trinity River through saturated bedrock. The study involved a capacitively-coupled resistivity survey and inverse modeling to obtain true or actual resistivity from apparent resistivity. The apparent resistivity was processed using an inverse modeling software program. The results of this program were used to generate distributions (images) of actual resistivity referred to as inverted sections or profiles. The images along the five profiles show a wide range of resistivity values. The two profiles nearest the West Fork Trinity River generally showed less resistivity than the three other profiles.

Electrically Variable Resistive Memory Devices

NASA Technical Reports Server (NTRS)

Liu, Shangqing; Wu, Nai-Juan; Ignatiev, Alex; Charlson, E. J.

2010-01-01

Nonvolatile electronic memory devices that store data in the form of electrical- resistance values, and memory circuits based on such devices, have been invented. These devices and circuits exploit an electrically-variable-resistance phenomenon that occurs in thin films of certain oxides that exhibit the colossal magnetoresistive (CMR) effect. It is worth emphasizing that, as stated in the immediately preceding article, these devices function at room temperature and do not depend on externally applied magnetic fields. A device of this type is basically a thin film resistor: it consists of a thin film of a CMR material located between, and in contact with, two electrical conductors. The application of a short-duration, low-voltage current pulse via the terminals changes the electrical resistance of the film. The amount of the change in resistance depends on the size of the pulse. The direction of change (increase or decrease of resistance) depends on the polarity of the pulse. Hence, a datum can be written (or a prior datum overwritten) in the memory device by applying a pulse of size and polarity tailored to set the resistance at a value that represents a specific numerical value. To read the datum, one applies a smaller pulse - one that is large enough to enable accurate measurement of resistance, but small enough so as not to change the resistance. In writing, the resistance can be set to any value within the dynamic range of the CMR film. Typically, the value would be one of several discrete resistance values that represent logic levels or digits. Because the number of levels can exceed 2, a memory device of this type is not limited to binary data. Like other memory devices, devices of this type can be incorporated into a memory integrated circuit by laying them out on a substrate in rows and columns, along with row and column conductors for electrically addressing them individually or collectively.

Identification of native angiotensin-I converting enzyme inhibitory peptides in commercial soybean based infant formulas using HPLC-Q-ToF-MS.

PubMed

Puchalska, Patrycja; Concepción García, M; Luisa Marina, M

2014-08-15

This work evaluates, the presence of native antihypertensive peptides in five soybean-based infant formulas (SBIFs). SBIFs peptide extracts (<10 kDa) and their sub-fractions (5-10 kDa, 3-5 kDa, and <3 kDa) from a variety of samples were obtained by ultrafiltration and ACE inhibitory activity was determined. The highest activities were observed in the smaller (<5 kDa) peptide fractions. A set of peptides present in various SBIFs were studied, and identified using HPLC-Q-ToF-MS. Despite ACE inhibitory activity decreasing after in vitro gastrointestinal digestion, it still remained at a high value (IC50 values of 18.2±0.1 and 4.9±0.1 μg/mL). Peptides resisting the action of gastrointestinal enzymes were identified and compared to previously identified peptides, highlighting the presence of peptide RPSYT. This peptide was synthesised, its antihypertensive and antioxidant activity were evaluated, and its resistance to in vitro gastrointestinal digestion and to high processing temperatures were studied. Copyright © 2014 Elsevier Ltd. All rights reserved.

Optimisation of the reaction conditions for the production of cross-linked starch with high resistant starch content.

PubMed

Kahraman, Kevser; Koksel, Hamit; Ng, Perry K W

2015-05-01

The optimum reaction conditions (temperature and pH) for the preparation of cross-linked (CL) corn and wheat starches with maximum resistant starch (RS) content were investigated by using response surface methodology (RSM). According to the preliminary results, five levels were selected for reaction temperature (38-70 °C) and pH (10-12) in the main study. RS contents of the CL corn and wheat starch samples increased with increasing temperature and pH, and pH had a greater influence on RS content than had temperature. The maximum RS content (with a maximum p value of 0.4%) was obtained in wheat starch cross-linked at 38 °C and pH 12. In the case of CL corn starch, the optimum condition was 70 °C and pH 12. CL corn and wheat starch samples were also produced separately under the optimum conditions and their RS contents were 80.4% and 83.9%, respectively. These results were also in agreement with the values predicted by RSM. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Galvanic Sensor for Monitoring the Corrosion Condition of the Concrete Reinforcing Steel: Relationship Between the Galvanic and the Corrosion Currents

PubMed Central

Pereira, Elsa Vaz; Figueira, Rita Bacelar; Salta, Maria Manuela Lemos; da Fonseca, Inês Teodora Elias

2009-01-01

This work reports a study carried out on the design and performance of galvanic and polarization resistance sensors to be embedded in concrete systems for permanent monitoring of the corrosion condition of reinforcing steel, aiming to establish a correlation between the galvanic currents, Igal, and the corrosion currents, Icorr, estimated from the polarization resistance, Rp. Sensors have been tested in saturated Ca(OH)2 aqueous solutions, under a variety of conditions, simulating the most important parameters that can accelerate the corrosion of concrete reinforcing steel, such as carbonation, ingress of chloride ions, presence or absence of O2. For all the conditions, the influence of temperature (20 to 55 °C) has also been considered. From this study, it could be concluded that the galvanic currents are sensitive to the various parameters following a trend similar to that of the Rp values. A relationship between the galvanic and the corrosion current densities was obtained and the limiting values of the Igal, indicative of the state condition of the reinforcing steel for the designed sensor, were established. PMID:22291514

Stoichiometry and tribological behavior of thick Ta(N) coatings produced by direct current magnetron sputtering (DCMS)

NASA Astrophysics Data System (ADS)

Guo, Xiaotong; Niu, Yunsong; Chen, Minghui; Sun, Wenyao; Zhu, Shenglong; Wang, Fuhui

2018-01-01

Thick Ta(N) coating of 51 μm has been successfully obtained by DCMS technology. Ta(N) is a kind of distorted Ta matrix, which is inter-soluble with N-defect lattice structure, forming the disabled bcc structure. From the XRD and XPS investigations, the composition of Ta(N) coating is consisted of bcc-Ta and bcc-TaN0.06, while that of Ta coating mainly contains β-Ta phase. It can be concluded from wear test, nanoindentation test and SEM observations, wear resistance of Ta(N) coating is much better than that of Ta coating, due to its high hardness, H/E, H3/E2 value and low COF value. The wear mechanism of Ta coating is the compound fatigue and abrasive wear, while that of Ta(N) coating is transformed into adhesive wear mechanism. The secondary adhesion of the plastic deformation for the Ta(N) coating can reinforce the coated surface, to improve the load-bearing and anti-wear capacities, and thus improve the wear resistance.

Determination of surface resistance and magnetic penetration depth of superconducting YBa2Cu3O(7-delta) thin films by microwave power transmission measurements

NASA Technical Reports Server (NTRS)

Bhasin, K. B.; Warner, J. D.; Miranda, F. A.; Gordon, W. L.; Newman, H. S.

1991-01-01

A novel waveguide power transmission measurement technique was developed to extract the complex conductivity of superconducting thin films at microwave frequencies. The microwave conductivity was taken of two laser ablated YBa2Cu3O(7-delta) thin films on LaAlO3 with transition temperatures of approximately 86.3 and 82 K, respectively, in the temperature range 25 to 300 K. From the conductivity values, the penetration depth was found to be approximately 0.54 and 0.43 micron, and the surface resistance (R sub s) to be approximately 24 and 36 micro-Ohms at 36 GHz and 76 K for the two films under consideration. The R sub s values were compared with those obtained from the change in the Q-factor of a 36 GHz Te sub 011-mode (OFHC) copper cavity by replacing one of its end walls with the superconducting sample. This technique allows noninvasive characterization of high transition superconducting thin films at microwave frequencies.

Determination of surface resistance and magnetic penetration depth of superconducting YBa2Cu3O(7-delta) thin films by microwave power transmission measurements

NASA Technical Reports Server (NTRS)

Bhasin, K. B.; Warner, J. D.; Miranda, F. A.; Gordon, W. L.; Newman, H. S.

1990-01-01

A novel waveguide power transmission measurement technique was developed to extract the complex conductivity of superconducting thin films at microwave frequencies. The microwave conductivity was taken of two laser ablated YBa2Cu3O(7-delta) thin films on LaAlO3 with transition temperatures of approx. 86.3 and 82 K, respectively, in the temperature range 25 to 300 K. From the conductivity values, the penetration depth was found to be approx. 0.54 and 0.43 micron, and the surface resistance (R sub s) to be approx. 24 and 36 micro-Ohms at 36 GHz and 76 K for the two films under consideration. The R sub s values were compared with those obtained from the change in the Q-factor of a 36 GHz Te sub 011-mode (OFHC) copper cavity by replacing one of its end walls with the superconducting sample. This technique allows noninvasive characterization of high transition temperature superconducting thin films at microwave frequencies.

Simultaneous quantification of antibiotics in wastewater from pig farms by capillary electrophoresis.

PubMed

Díaz-Quiroz, Carlos A; Francisco Hernández-Chávez, J; Ulloa-Mercado, Gabriela; Gortáres-Moroyoqui, Pablo; Martínez-Macías, Rosario; Meza-Escalante, Edna; Serrano-Palacios, Denisse

2018-06-15

Pig farming is an important activity in the economic development of Mexico with millions of tons of meat produced annually. Antibiotics are used in therapeutic dose to prevent diseases, and sometimes as growth promoters. These compounds are not completely metabolized; they are carried into the environment in its active form at concentrations that could induce antibiotic resistance in bacteria, which could be transferred to human pathogens by horizontal gene transfer. The objective of this work was to develop methods of analysis for simultaneous quantification of the antibiotics Oxytetracycline (OXT), Chlortetracycline (CLT), Enrofloxacin (ENRO) and Ciprofloxacin (CIPRO) by field-amplified sampling injection in capillary zone electrophoresis (FASI-CZE). The method was validated by parameters of (1) linearity, obtaining a lineal range of 0.05 at 1 μg mL -1 for ENRO and CIPRO, and from 0.1 to 1 μg mL -1 for OXT and CLT; (2) precision, obtaining values <5% of standard deviation for CIPRO and ENRO and <10% of standard deviation for OXT and CLT; (3) accuracy, with recovery values from 93 to 115%; (4) selectivity, with values of resolution >2 for the all antibiotics tested. To prove the method, a sample of wastewater from a local pig farm was analyzed, detecting a concentration of 0.140 ± 0.009 for OXT. This concentration was higher than the minimal selective concentration, indicating the point in which resistance to a determined antibiotic could develop. The methods were validated with precision and sensitivity comparable to chromatographic methods, which can be used to analyze wastewater from pig farms directly. Copyright © 2018 Elsevier B.V. All rights reserved.

Improved thermoelectric properties of Bi2Te3-xSex alloys by melt spinning and resistance pressing sintering

NASA Astrophysics Data System (ADS)

Cai, Xinzhi; Fan, Xi'an; Rong, Zhenzhou; Yang, Fan; Gan, Zhanghua; Li, Guangqiang

2014-03-01

Starting from bismuth, tellurium and selenium chunks, n-type Bi2Te3-xSex (x ⩽ 0.3) alloys were obtained by melt spinning (MS) combined with a resistance pressing sintering (RPS) process. The phases, microstructures and compositions of the samples were evaluated by x-ray diffraction, field emission scanning electron microscopy, and energy dispersive x-ray spectroscopy during each step in the preparation process, respectively. The influences of Se doping, MS and RPS processes on the thermoelectric (TE) properties of Bi2Te3-xSex alloys were investigated in detail. The Bi2Te3-xSex powders could be well compacted by the RPS process and the relative densities of the bulks prepared by RPS were all higher than 96%. The partially oriented lamellar structure could be observed at some regions of the samples prepared by RPS, and the monolayer thickness of the lamellar structure in the MS-RPS samples was smaller than that in the smelting-RPS sample. The MS process was confirmed as an excellent method to obtain fine microstructures and low lattice thermal conductivity for the TE materials. All evidence about electrical and thermal transport properties suggested that suitably increasing the Se content could effectively improve the ZT value. The maximum ZT value of 0.84 was obtained for the Bi2Te2.7Se0.3 prepared by MS-RPS at 423 K. As opposed to the conventional hot pressing and spark plasma sintering, the RPS method introduced here is more suitable for practical industrial application due to its cost saving and high efficiency.

Design and Implementation of RF Energy Harvesting System for Low-Power Electronic Devices

NASA Astrophysics Data System (ADS)

Uzun, Yunus

2016-08-01

Radio frequency (RF) energy harvester systems are a good alternative for energizing of low-power electronics devices. In this work, an RF energy harvester is presented to obtain energy from Global System for Mobile Communications (GSM) 900 MHz signals. The energy harvester, consisting of a two-stage Dickson voltage multiplier circuit and L-type impedance matching circuits, was designed, simulated, fabricated and tested experimentally in terms of its performance. Simulation and experimental works were carried out for various input power levels, load resistances and input frequencies. Both simulation and experimental works have been carried out for this frequency band. An efficiency of 45% is obtained from the system at 0 dBm input power level using the impedance matching circuit. This corresponds to the power of 450 μW and this value is sufficient for many low-power devices. The most important parameters affecting the efficiency of the RF energy harvester are the input power level, frequency band, impedance matching and voltage multiplier circuits, load resistance and the selection of diodes. RF energy harvester designs should be optimized in terms of these parameters.

Ferromagnetic tunnel contacts to graphene: Contact resistance and spin signal

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

Cubukcu, M.; Laczkowski, P.; Vergnaud, C.

2015-02-28

We report spin transport in CVD graphene-based lateral spin valves using different magnetic contacts. We compared the spin signal amplitude measured on devices where the cobalt layer is directly in contact with the graphene to the one obtained using tunnel contacts. Although a sizeable spin signal (up to ∼2 Ω) is obtained with direct contacts, the signal is strongly enhanced (∼400 Ω) by inserting a tunnel barrier. In addition, we studied the resistance-area product (R.A) of a variety of contacts on CVD graphene. In particular, we compared the R.A products of alumina and magnesium oxide tunnel barriers grown by sputteringmore » deposition of aluminum or magnesium and subsequent natural oxidation under pure oxygen atmosphere or by plasma. When using an alumina tunnel barrier on CVD graphene, the R.A product is high and exhibits a large dispersion. This dispersion can be highly reduced by using a magnesium oxide tunnel barrier, as for the R.A value. This study gives insight in the material quest for reproducible and efficient spin injection in CVD graphene.« less

Research of Influence of Noise Pollution on the Value of the Threshold Current Tangible

NASA Astrophysics Data System (ADS)

Khanzhina, Olga; Sidorov, Alexander; Zykina, Ekaterina

2017-12-01

Stable safety while working on electrical installations can be achieved by following the rules of the electrical safety. Today maximum permissible levels of touch voltage and electric current flow through any part of a person’s body are established by Russian Federation GOST system 12.1.038-82. Unfortunately, recommended by International Electrotechnical Commission (IEC) maximum allowable amount of electric current and voltage level do not take into account interaction between said electric current and other physical factors; noise, in particular. The influence of sound frequency and its pressure level on body resistance has been proven earlier in thesis by V.V. Katz. Studies of the noise effects on the value of the threshold current tangible have been renewed in laboratories of Life Safety Department in South Ural State University. To obtain reliable results, testing facility that includes anechoic chamber, sources of simulated voltages and noise and a set of recording instruments was designed and built. As a rule, noise influence on electrotechnical personnel varies depending on noise level or/and the duration of its impact. According to modern theories, indirect noise influence on various organs and systems through central nervous system has to be considered. Differential evaluation of noise pollution and its correlation with emerged effects can be obtained with the usage of the dose approach. First of all, there were conducted studies, in which frequency of the applied voltage (f) was to 50 Hz. Voltages and currents that caused sensations before and during 97 dB noise affections were measured. Obtained dependence led to questioning previous researches results of the necessity of reducing the amperage of tripping protection devices. At the same time electrical resistance changes of human body were being studied. According to those researches, no functional dependence between fluctuations in the magnitude of the resistance of human body to electric current flow and constant noise affection were found. Taking into account that contradiction, additional studies of primary electrical safety criteria for cases when exposed to high frequency noise pollution were conducted.

The effect of woven and non-woven fiber structure on mechanical properties polyester composite reinforced kenaf

NASA Astrophysics Data System (ADS)

Ratim, S.; Bonnia, N. N.; Surip, S. N.

2012-07-01

The effects of woven and non-woven kenaf fiber on mechanical properties of polyester composites were studied at different types of perform structures. Composite polyester reinforced kenaf fiber has been prepared via hand lay-up process by varying fiber forms into plain weave, twill and mats structure. The reinforcing efficiency of different fiber structure was compared with control of unreinforced polyester sample. It was found that the strength and stiffness of the composites are largely affected by fiber structure. A maximum value for tensile strength of composite was obtained for twill weave pattern of fiber structure while no significant different for plain weave and mat structure. The elastic modulus of composite has shown some improvement on plain and twill weave pattern. Meanwhile, lower value of modulus elasticity achieved by mats structure composite as well as control sample. The modulus of rupture and impact resistance were also analyzed. The improvement of modulus of rupture value can be seen on plain and twill weave pattern. However impact resistance doesn't show significant improvement in all types of structure except for mat fiber. The mechanical properties of kenaf fiber reinforced polyester composite found to be increased with woven and non-woven fiber structures in composite.

Characterization of a Laser Surface-Treated Martensitic Stainless Steel.

PubMed

Al-Sayed, S R; Hussein, A A; Nofal, A A; Hassab Elnaby, S I; Elgazzar, H

2017-05-29

Laser surface treatment was carried out on AISI 416 machinable martensitic stainless steel containing 0.225 wt.% sulfur. Nd:YAG laser with a 2.2-KW continuous wave was used. The aim was to compare the physical and chemical properties achieved by this type of selective surface treatment with those achieved by the conventional treatment. Laser power of different values (700 and 1000 W) with four corresponding different laser scanning speeds (0.5, 1, 2, and 3 m•min-1) was adopted to reach the optimum conditions for impact toughness, wear, and corrosion resistance for laser heat treated (LHT) samples. The 0 °C impact energy of LHT samples indicated higher values compared to the conventionally heat treated (CHT) samples. This was accompanied by the formation of a hard surface layer and a soft interior base metal. Microhardness was studied to determine the variation of hardness values with respect to the depth under the treated surface. The wear resistance at the surface was enhanced considerably. Microstructure examination was characterized using optical and scanning electron microscopes. The corrosion behavior of the LHT samples was also studied and its correlation with the microstructures was determined. The corrosion data was obtained in 3.5% NaCl solution at room temperature by means of a potentiodynamic polarization technique.

Characterization of a Laser Surface-Treated Martensitic Stainless Steel

PubMed Central

Al-Sayed, S. R.; Hussein, A. A.; Nofal, A. A.; Hassab Elnaby, S. I.; Elgazzar, H.

2017-01-01

Laser surface treatment was carried out on AISI 416 machinable martensitic stainless steel containing 0.225 wt.% sulfur. Nd:YAG laser with a 2.2-KW continuous wave was used. The aim was to compare the physical and chemical properties achieved by this type of selective surface treatment with those achieved by the conventional treatment. Laser power of different values (700 and 1000 W) with four corresponding different laser scanning speeds (0.5, 1, 2, and 3 m·min−1) was adopted to reach the optimum conditions for impact toughness, wear, and corrosion resistance for laser heat treated (LHT) samples. The 0 °C impact energy of LHT samples indicated higher values compared to the conventionally heat treated (CHT) samples. This was accompanied by the formation of a hard surface layer and a soft interior base metal. Microhardness was studied to determine the variation of hardness values with respect to the depth under the treated surface. The wear resistance at the surface was enhanced considerably. Microstructure examination was characterized using optical and scanning electron microscopes. The corrosion behavior of the LHT samples was also studied and its correlation with the microstructures was determined. The corrosion data was obtained in 3.5% NaCl solution at room temperature by means of a potentiodynamic polarization technique. PMID:28772955

Insulin resistance index (HOMA-IR) in the differentiation of patients with non-alcoholic fatty liver disease and healthy individuals.

PubMed

Salgado, Ana Lúcia Farias de Azevedo; Carvalho, Luciana de; Oliveira, Ana Claudia; Santos, Virgínia Nascimento dos; Vieira, Jose Gilberto; Parise, Edison Roberto

2010-01-01

Due to its good correlation to glycemic clamp, HOMA-IR has been widely utilized as insulin resistance index in clinical and epidemiological studies involving non-alcoholic fatty liver disease carriers. However, values used for this parameter have shown large variability. To identify the HOMA-IR cut value that best distinguishes non-diabetic non-alcoholic fatty liver disease patients from a control group. One hundred sixteen non-alcoholic fatty liver disease patients were studied, diagnosed by clinical, biochemical, and liver image or biopsy criteria, and 88 healthy individuals, without any liver disease and testing for oral glucose tolerance within normality. These groups did not differ in age and gender. All were submitted to oral glucose tolerance test and blood samples were collected for glucose and insulin measurements by immunofluorometric method. HOMA-IR was calculated according to the formula: fasting insulin (microU/L) x fasting glucose (nmol/L)/22.5. NAFLD patients showed higher insulin, glycemia, and HOMA-IR values than control group, even when excluding glucose intolerant and diabetes mellitus patients by their glycemic curves. HOMA-IR 75th percentile for control group was 1.78 and the best area under the curve index was obtained for HOMA-IR values of 2.0 [AUC= 0.840 (0.781-0.899 CI 95%), sensitivity (Se): 85%, specificity (Sp): 83%] while value 2.5 showed best specificity without important loss in sensitivity [AUC=0,831 (0.773-0.888) Se = 72%, Sp = 94%]. HOMA-IR values above or equal to 2.0 or 2.5 show enhanced diagnostic value in distinguishing non-alcoholic fatty liver disease carriers from control group individuals.

Radial distribution of the contributions to band broadening of a silica-based semi-preparative monolithic column.

PubMed

Abia, Jude A; Mriziq, Khaled S; Guiochon, Georges A

2009-04-01

Using an on-column local electrochemical microdetector operated in the amperometric mode, band elution profiles were recorded at different radial locations at the exit of a 10 mm id, 100 mm long silica-based monolithic column. HETP plots were then acquired at each of these locations, and all these results were fitted to the Knox equation. This provided a spatial distribution of the values of the eddy diffusion (A), the molecular diffusion (B), and the resistance to the kinetics of mass transfer (C) terms. Results obtained indicate that the wall region yields higher A values and smaller C values than the central core region. Significant radial fluctuations of these contributions to band broadening occur throughout the exit column cross-section. This phenomenon is due to the structural radial heterogeneity of the column.

Combined antitumor effects of bee venom and cisplatin on human cervical and laryngeal carcinoma cells and their drug resistant sublines.

PubMed

Gajski, Goran; Čimbora-Zovko, Tamara; Rak, Sanjica; Rožman, Marko; Osmak, Maja; Garaj-Vrhovac, Vera

2014-12-01

In the present study, we investigated the possible combined anticancer ability of bee venom (BV) and cisplatin towards two pairs of tumour cell lines: parental cervical carcinoma HeLa cells and their cisplatin-resistant HeLa CK subline,as well as laryngeal carcinoma HEp-2 cells and their cisplatin-resistant CK2 subline. Additionally, we identified several peptides of BV in the BV sample used in the course of the study and determined the exact concentration of MEL. BV applied alone in concentrations of 30 to 60 μg ml(–1) displayed dose-dependent cytotoxicity against all cell lines tested. Cisplatin-resistant cervical carcinoma cells were more sensitive to BV than their parental cell lines (IC(50) values were 52.50 μg ml(–1) for HeLa vs.47.64 μg ml(–1) for HeLa CK cells), whereas opposite results were obtained for cisplatin-resistant laryngeal carcinoma cells (IC(50) values were 51.98 μg ml(–1) for HEp-2 vs. > 60.00 μg ml(–1) for CK2 cells). Treatment with BV alone induced a necrotic type of cell death, as shown by characteristic morphological features, fast staining with ethidium-bromide and a lack of cleavage of apoptotic marker poly (ADP-ribose) polymerase (PARP) on Western blot. Combined treatment of BV and cisplatin induced an additive and/or weak synergistic effect towards tested cell lines, suggesting that BV could enhance the killing effect of selected cells when combined with cisplatin. Therefore, a greater anticancer effect could be triggered if BV was used in the course of chemotherapy. Our results suggest that combined treatment with BV could be useful from the point of minimizing the cisplatin concentration during chemotherapy, consequently reducing and/or postponing the development of cisplatin resistance.

Molecular recognition of live methicillin-resistant staphylococcus aureus cells using DNA aptamers

PubMed Central

Turek, Diane; Van Simaeys, Dimitri; Johnson, Judith; Ocsoy, Ismail; Tan, Weihong

2014-01-01

AIM To generate DNA-aptamers binding to Methicillin-resistant Staphylococcus aureus (MRSA). METHODS The Cell-Systematic Evolution of Ligands by Exponential Enrichment (SELEX) technology was used to run the selection against MRSA bacteria and develop target-specific aptamers. MRSA bacteria were targeted while Enterococcus faecalis bacteria were used for counter selection during that process. Binding assays to determine the right aptamer candidates as well as binding assays on clinical samples were performed through flow cytometry and analyzed using the FlowJo software. The characterization of the aptamers was done by determination of their Kd values and determined by analysis of flow data at different aptamer concentration using SigmaPlot. Finally, the recognition of the complex Gold-nanoparticle-aptamer to the bacteria cells was observed using transmission electron microscopy (TEM). RESULTS During the cell-SELEX selection process, 17 rounds were necessary to generate enrichment of the pool. While the selection was run using fixed cells, it was shown that the binding of the pools with live cells was giving similar results. After sequencing and analysis of the two last pools, four sequences were identified to be aptamer candidates. The characterization of those aptamers showed that based on their Kd values, DTMRSA4 presented the best binding with a Kd value of 94.61 ± 18.82 nmol/L. A total of ten clinical samples of MRSA , S. aureus and Enterococcus faecalis were obtained to test those aptamers and determine their binding on a panel of samples. DTMRSA1 and DTMRSA3 showed the best results regarding their specificity to MRSA , DTMRSA1 being the most specific of all. Finally, those aptamers were coupled with gold-nanoparticle and their binding to MRSA cells was visualized through TEM showing that adduction of nanoparticles on the aptamers did not change their binding property. CONCLUSION A total of four aptamers that bind to MRSA were obtained with Kd values ranking from 94 to 200 nmol/L. PMID:25436184

Molecular recognition of live methicillin-resistant staphylococcus aureus cells using DNA aptamers.

PubMed

Turek, Diane; Van Simaeys, Dimitri; Johnson, Judith; Ocsoy, Ismail; Tan, Weihong

2013-01-01

To generate DNA-aptamers binding to Methicillin-resistant Staphylococcus aureus (MRSA) . The Cell-Systematic Evolution of Ligands by Exponential Enrichment (SELEX) technology was used to run the selection against MRSA bacteria and develop target-specific aptamers. MRSA bacteria were targeted while Enterococcus faecalis bacteria were used for counter selection during that process. Binding assays to determine the right aptamer candidates as well as binding assays on clinical samples were performed through flow cytometry and analyzed using the FlowJo software. The characterization of the aptamers was done by determination of their K d values and determined by analysis of flow data at different aptamer concentration using SigmaPlot. Finally, the recognition of the complex Gold-nanoparticle-aptamer to the bacteria cells was observed using transmission electron microscopy (TEM). During the cell-SELEX selection process, 17 rounds were necessary to generate enrichment of the pool. While the selection was run using fixed cells, it was shown that the binding of the pools with live cells was giving similar results. After sequencing and analysis of the two last pools, four sequences were identified to be aptamer candidates. The characterization of those aptamers showed that based on their K d values, DTMRSA4 presented the best binding with a K d value of 94.61 ± 18.82 nmol/L. A total of ten clinical samples of MRSA , S. aureus and Enterococcus faecalis were obtained to test those aptamers and determine their binding on a panel of samples. DTMRSA1 and DTMRSA3 showed the best results regarding their specificity to MRSA , DTMRSA1 being the most specific of all. Finally, those aptamers were coupled with gold-nanoparticle and their binding to MRSA cells was visualized through TEM showing that adduction of nanoparticles on the aptamers did not change their binding property. A total of four aptamers that bind to MRSA were obtained with K d values ranking from 94 to 200 nmol/L.

Interferon-γ-inducible protein-10 in chronic hepatitis C: Correlations with insulin resistance, histological features & sustained virological response.

PubMed

Crisan, Dana; Grigorescu, Mircea Dan; Radu, Corina; Suciu, Alina; Grigorescu, Mircea

2017-04-01

One of the multiple factors contributing to virological response in chronic hepatitis C (CHC) is interferon-gamma-inducible protein-10 (IP-10). Its level reflects the status of interferon-stimulated genes, which in turn is associated with virological response to antiviral therapy. The aim of this study was to evaluate the role of serum IP-10 levels on sustained virological response (SVR) and the association of this parameter with insulin resistance (IR) and liver histology. Two hundred and three consecutive biopsy proven CHC patients were included in the study. Serum levels of IP-10 were determined using ELISA method. IR was evaluated by homeostasis model assessment-IR (HOMA-IR). Histological features were assessed invasively by liver biopsy and noninvasively using FibroTest, ActiTest and SteatoTest. Predictive factors for SVR and their interrelations were assessed. A cut-off value for IP-10 of 392 pg/ml was obtained to discriminate between responders and non-responders. SVR was obtained in 107 patients (52.70%). Area under the receiver operating characteristic curve for SVR was 0.875 with a sensitivity of 91.6 per cent, specificity 74.7 per cent, positive predictive value 80.3 per cent and negative predictive value 88.7 per cent. Higher values of IP-10 were associated with increasing stages of fibrosis (P<0.01) and higher grades of inflammation (P=0.02, P=0.07) assessed morphologically and noninvasively through FibroTest and ActiTest. Significant steatosis and IR were also associated with increased levels of IP-10 (P=0.01 and P=0.02). In multivariate analysis, IP-10 levels and fibrosis stages were independently associated with SVR. Our findings showed that the assessment of serum IP-10 level could be a predictive factor for SVR and it was associated with fibrosis, necroinflammatory activity, significant steatosis and IR in patients with chronic HCV infection.

Determination of Flow Resistance Coefficient for Vegetation in Open Channel: Laboratory study

NASA Astrophysics Data System (ADS)

Aliza Ahmad, Noor; Ali, ZarinaMd; Arish, Nur Aini Mohd; Munirah Mat Daud, Azra; Fatin Amirah Alias, Nur

2018-04-01

This study focused on determination of flow resistances coefficient for grass in an open channel. Laboratory works were conducted to examine the effects of varying of roughness elements on the flume to determine flow resistance coefficient and also to determine the optimum flow resistance with five different flow rate, Q. Laboratory study with two type of vegetation which are Cow Grass and Pearl Grass were implementing to the bed of a flume. The roughness coefficient, n value is determine using Manning’s equation while Soil Conservation Services (SCS) method was used to determine the surface resistance. From the experiment, the flow resistance coefficient for Cow Grass in range 0.0008 - 0.0039 while Pearl Grass value for the flow resistance coefficient are in between 0.0013 - 0.0054. As a conclusion the vegetation roughness value in open channel are depends on density, distribution type of vegetation used and physical characteristic of the vegetation itself

Overview of the development of quinolone resistance in Salmonella species in China, 2005–2016

PubMed Central

Song, Qifa; Xu, Zhaojun; Gao, Hong; Zhang, Danyang

2018-01-01

Purpose Several factors contribute to the complexity of quinolone resistance in Salmonella, including >2000 different Salmonella serotypes, a variety of hosts for Salmonella, and wide use of quinolones in human beings and animals. We thus aimed to obtain an overview of the development of quinolone resistance and relevant molecular mechanisms of such a resistance in Salmonella species. Materials and methods A total of 1,776 Salmonella isolates were collected in Ningbo, China, between 2005 and 2016. Antimicrobial susceptibility to quinolone and relevant genetic mechanisms in these isolates were retrospectively analyzed. Results The ratio for ciprofloxacin (CIP) resistant:reduced CIP susceptible:CIP susceptible was 26:522:1,228. CIP resistance was found in nine of 51 serotypes: Derby, London, Kentucky, Indiana, Corvallis, Rissen, Hadar, Typhimurium, and Agona. Of 26 CIP-resistant isolates, all were concurrently resistant to ampicillin and 21 were also concurrently resistant to cefotaxime and produced extended-spectrum β-lactamase (ESBL). The minimal inhibitory concentration values were at three levels: 2–4 μg/mL (serotypes except for Kentucky and Indiana), 16 μg/mL (one Kentucky isolate), and >32 μg/mL (Indiana isolates). As with the three most common serotypes, Salmonella Typhi showed quickly increased prevalence of reduced CIP susceptibility in recent years, Salmonella Enteritidis remained at a high prevalence of reduced CIP susceptibility throughout the study period, and several isolates of Salmonella Typhimurium were resistant to CIP. Transferable plasmid-mediated quinolone resistance gene qnrB was only found in all CIP-resistant isolates. In contrast, gyrA mutations were often found in reduced CIP-susceptible isolates and were not necessarily found in all CIP-resistant isolates. Conclusion We conclude that in Salmonella, there exists a high prevalence of reduced CIP susceptibility and a low prevalence of CIP resistance, which focuses on several serotypes. Our study also demonstrates that, rather than gyrA mutations, qnrB is the most common indicator for CIP resistance. PMID:29520157

Optimal Electrode Selection for Electrical Resistance Tomography in Carbon Fiber Reinforced Polymer Composites

PubMed Central

Escalona Galvis, Luis Waldo; Diaz-Montiel, Paulina; Venkataraman, Satchi

2017-01-01

Electrical Resistance Tomography (ERT) offers a non-destructive evaluation (NDE) technique that takes advantage of the inherent electrical properties in carbon fiber reinforced polymer (CFRP) composites for internal damage characterization. This paper investigates a method of optimum selection of sensing configurations for delamination detection in thick cross-ply laminates using ERT. Reduction in the number of sensing locations and measurements is necessary to minimize hardware and computational effort. The present work explores the use of an effective independence (EI) measure originally proposed for sensor location optimization in experimental vibration modal analysis. The EI measure is used for selecting the minimum set of resistance measurements among all possible combinations resulting from selecting sensing electrode pairs. Singular Value Decomposition (SVD) is applied to obtain a spectral representation of the resistance measurements in the laminate for subsequent EI based reduction to take place. The electrical potential field in a CFRP laminate is calculated using finite element analysis (FEA) applied on models for two different laminate layouts considering a set of specified delamination sizes and locations with two different sensing arrangements. The effectiveness of the EI measure in eliminating redundant electrode pairs is demonstrated by performing inverse identification of damage using the full set and the reduced set of resistance measurements. This investigation shows that the EI measure is effective for optimally selecting the electrode pairs needed for resistance measurements in ERT based damage detection. PMID:28772485

Resistivity control of unintentionally doped GaN films

NASA Astrophysics Data System (ADS)

Grzegorczyk, A. P.; Macht, L.; Hageman, P. R.; Rudzinski, M.; Larsen, P. K.

2005-05-01

GaN epilayers were grown on sapphire substrates via low temperature GaN and AlN nucleation layers (NL) by metalorganic chemical vapor phase epitaxy (MOCVD). The morphology of the individual NLs strongly depends on the carrier gas used during the growth and recrystallization and this is the key factor for control of the resistivity of the GaN layer grown on it. The GaN nucleation layer grown in presence of N2 has a higher density of islands with a statistically smaller diameter than the samples grown in H2 atmosphere. The NL grown in N2 enables the growth GaN with a sheet resistivity higher than 3×104 cm as opposed to a 0.5 cm value obtained for the NL grown in H2. Introduction of an additional intermediate (IL) low temperature (GaN or AlN) nucleation layer changes the GaN epilayer resistivity to about 50 cm, regardless of the carrier gas used during the growth of the IL. Defect selective etching demonstrated that control of the type and density of the dislocations in GaN enables the growth of highly resistive layers without any intentional acceptor doping (Mg, Zn). It will be demonstrated that by changing the ratio of edge type to screw dislocations the resistivity of the layer can be changed by a few orders of magnitude.

High Resistivity Lipid Bilayers Assembled on Polyelectrolyte Multilayer Cushions: An Impedance Study.

PubMed

Diamanti, Eleftheria; Gregurec, Danijela; Rodríguez-Presa, María José; Gervasi, Claudio A; Azzaroni, Omar; Moya, Sergio E

2016-06-28

Supported membranes on top of polymer cushions are interesting models of biomembranes as cell membranes are supported on a polymer network of proteins and sugars. In this work lipid vesicles formed by a mixture of 30% 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 70% 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) are assembled on top of a polyelectrolyte multilayer (PEM) cushion of poly(allylamine hydrochloride) (PAH) and poly(styrene sodium sulfonate) (PSS). The assembly results in the formation of a bilayer on top of the PEM as proven by means of the quartz crystal microbalance with dissipation technique (QCM-D) and by cryo-transmission electron microscopy (cryo-TEM). The electrical properties of the bilayer are studied by electrochemical impedance spectroscopy (EIS). The bilayer supported on the PEMs shows a high resistance, on the order of 10(7) Ω cm(2), which is indicative of a continuous, dense bilayer. Such resistance is comparable with the resistance of black lipid membranes. This is the first time that such values are obtained for lipid bilayers supported on PEMs. The assembly of polyelectrolytes on top of a lipid bilayer decreases the resistance of the bilayer up to 2 orders of magnitude. The assembly of the polyelectrolytes on the lipids induces defects or pores in the bilayer which in turn prompts a decrease in the measured resistance.

Optimal Electrode Selection for Electrical Resistance Tomography in Carbon Fiber Reinforced Polymer Composites.

PubMed

Escalona Galvis, Luis Waldo; Diaz-Montiel, Paulina; Venkataraman, Satchi

2017-02-04

Electrical Resistance Tomography (ERT) offers a non-destructive evaluation (NDE) technique that takes advantage of the inherent electrical properties in carbon fiber reinforced polymer (CFRP) composites for internal damage characterization. This paper investigates a method of optimum selection of sensing configurations for delamination detection in thick cross-ply laminates using ERT. Reduction in the number of sensing locations and measurements is necessary to minimize hardware and computational effort. The present work explores the use of an effective independence (EI) measure originally proposed for sensor location optimization in experimental vibration modal analysis. The EI measure is used for selecting the minimum set of resistance measurements among all possible combinations resulting from selecting sensing electrode pairs. Singular Value Decomposition (SVD) is applied to obtain a spectral representation of the resistance measurements in the laminate for subsequent EI based reduction to take place. The electrical potential field in a CFRP laminate is calculated using finite element analysis (FEA) applied on models for two different laminate layouts considering a set of specified delamination sizes and locations with two different sensing arrangements. The effectiveness of the EI measure in eliminating redundant electrode pairs is demonstrated by performing inverse identification of damage using the full set and the reduced set of resistance measurements. This investigation shows that the EI measure is effective for optimally selecting the electrode pairs needed for resistance measurements in ERT based damage detection.

Study of metal corrosion using ac impedance techniques in the STS launch environment

NASA Technical Reports Server (NTRS)

Calle, Luz M.

1989-01-01

AC impedance measurements were performed to investigate the corrosion resistance of 19 alloys under conditions similar to the STS launch environment. The alloys were: Zirconium 702, Hastelloy C-22, Inconel 625, Hastelloy C-276, Hastelloy C-4, Inconel 600, 7Mo + N, Ferralium 255, Inco Alloy G-3, 20Cb-3, SS 904L, Inconel 825, SS 304LN, SS 316L, SS 317L, ES 2205, SS 304L, Hastelloy B-2, and Monel 400. AC impedance data were gathered for each alloy after one hour immersion time in each of the following three electrolyte solutions: 3.55 percent NaCl, 3.55 percent NaCl-0.1N HCl, and 3.55 percent NaCl-1.0N HCl. The data were analyzed qualitatively using the Nyquist plot and quantitatively using the Bode plot. Polarization resistance, Rp, values were obtained using the Bode plot. Zirconium 702 was the most corrosion resistant alloy in the three electrolytes. The ordering of the other alloys according the their resistance to corrosion varied as the concentration of hydrochloric acid in the electrolyte increased. The corrosion resistance of Zirconium 702 and Ferralium 255 increased as the concentration of hydrochloric acid in the electrolyte increased. The corrosion resistance of the other 17 alloys decreased as the concentration of the hyrdochloric acid in the electrolyte increased.

Experimental Investigations on the Pull-Out Behavior of Tire Strips Reinforced Sands

PubMed Central

Li, Li-Hua; Chen, Yan-Jun; Ferreira, Pedro Miguel Vaz; Liu, Yong; Xiao, Heng-Lin

2017-01-01

Waste tires have excellent mechanical performance and have been used as reinforcing material in geotechnical engineering; however, their interface properties are poorly understood. To further our knowledge, this paper examines the pull-out characteristics of waste tire strips in a compacted sand, together with uniaxial and biaxial geogrids also tested under the same conditions. The analysis of the results shows that the interlocking effect and pull-out resistance between the tire strip and the sand is very strong and significantly higher than that of the geogrids. In the early stages of the pull-out test, the resistance is mainly provided by the front portion of the embedded tire strips, as the pull-out test continues, more and more of the areas towards the end of the tire strips are mobilized, showing a progressive failure mechanism. The deformations are proportional to the frictional resistance between the tire-sand interface, and increase as the normal stresses increase. Tire strips of different wear intensities were tested and presented different pull-out resistances; however, the pull-out resistance mobilization patterns were generally similar. The pull-out resistance values obtained show that rubber reinforcement can provide much higher pull-out forces than the geogrid reinforcements tested here, showing that waste tires are an excellent alternative as a reinforcing system, regardless of the environmental advantages. PMID:28773069

All-nanotube stretchable supercapacitor with low equivalent series resistance.

PubMed

Gilshteyn, Evgenia P; Amanbayev, Daler; Anisimov, Anton S; Kallio, Tanja; Nasibulin, Albert G

2017-12-12

We report high-performance, stable, low equivalent series resistance all-nanotube stretchable supercapacitor based on single-walled carbon nanotube film electrodes and a boron nitride nanotube separator. A layer of boron nitride nanotubes, fabricated by airbrushing from isopropanol dispersion, allows avoiding problem of high internal resistance and short-circuiting of supercapacitors. The device, fabricated in a two-electrode test cell configuration, demonstrates electrochemical double layer capacitance mechanism and retains 96% of its initial capacitance after 20 000 electrochemical charging/discharging cycles with the specific capacitance value of 82 F g -1 and low equivalent series resistance of 4.6 Ω. The stretchable supercapacitor prototype withstands at least 1000 cycles of 50% strain with a slight increase in the volumetric capacitance from 0.4 to 0.5 mF cm -3 and volumetric power density from 32 mW cm -3 to 40 mW cm -3 after stretching, which is higher than reported before. Moreover, a low resistance of 250 Ω for the as-fabricated stretchable prototype was obtained, which slightly decreased with the strain applied up to 200 Ω. Simple fabrication process of such devices can be easily extended making the all-nanotube stretchable supercapacitors, presented here, promising elements in future wearable devices.

Relationships between PEMFC Cathode Kinetic Losses and Contaminants’ Dipole Moment and Adsorption Energy on Pt

DOE PAGES

St-Pierre, Jean; Zhai, Yunfeng; Ge, Junjie

2016-01-05

A database summarizing the effects of 21 contaminants on the performance of proton exchange membrane fuel cells (PEMFCs) was used to examine relationships between cathode kinetic losses and contaminant physicochemical parameters. Impedance spectroscopy data were employed to obtain oxygen reduction kinetic resistances by fitting data in the 10-158 Hz range to a simplified equivalent circuit. The contaminant dipole moment and the adsorption energy of the contaminant on a Pt surface were chosen as parameters. Dipole moments did not correlate with dimensionless cathode kinetic resistances. In contrast, adsorption energies were quantitatively and linearly correlated with minimum dimensionless cathode kinetic resistances. Contaminantsmore » influence the oxygen reduction for contaminant adsorption energies smaller than -24.5 kJ mol -1, a value near the high limit of the adsorption energy of O 2 on Pt. Dimensionless cathode kinetic resistances linearly increase with decreasing O 2 adsorption energies below -24.5 kJ mol -1. Measured total cell voltage losses are mostly larger than the cathode kinetic losses calculated from kinetic resistance changes, which indicates the existence of other sources of performance degradation. Modifications to the experimental procedure are proposed to ensure that data are comparable on a similar basis and improve the correlation between contaminant adsorption energy and kinetic cell voltage losses.« less

Relationships between PEMFC Cathode Kinetic Losses and Contaminants’ Dipole Moment and Adsorption Energy on Pt

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

St-Pierre, Jean; Zhai, Yunfeng; Ge, Junjie

A database summarizing the effects of 21 contaminants on the performance of proton exchange membrane fuel cells (PEMFCs) was used to examine relationships between cathode kinetic losses and contaminant physicochemical parameters. Impedance spectroscopy data were employed to obtain oxygen reduction kinetic resistances by fitting data in the 10-158 Hz range to a simplified equivalent circuit. The contaminant dipole moment and the adsorption energy of the contaminant on a Pt surface were chosen as parameters. Dipole moments did not correlate with dimensionless cathode kinetic resistances. In contrast, adsorption energies were quantitatively and linearly correlated with minimum dimensionless cathode kinetic resistances. Contaminantsmore » influence the oxygen reduction for contaminant adsorption energies smaller than -24.5 kJ mol -1, a value near the high limit of the adsorption energy of O 2 on Pt. Dimensionless cathode kinetic resistances linearly increase with decreasing O 2 adsorption energies below -24.5 kJ mol -1. Measured total cell voltage losses are mostly larger than the cathode kinetic losses calculated from kinetic resistance changes, which indicates the existence of other sources of performance degradation. Modifications to the experimental procedure are proposed to ensure that data are comparable on a similar basis and improve the correlation between contaminant adsorption energy and kinetic cell voltage losses.« less

Computer-assisted Biology Learning Materials: Designing and Developing an Interactive CD on Spermatogenesis

NASA Astrophysics Data System (ADS)

Haviz, M.

2018-04-01

The purpose of this article is to design and develop an interactive CD on spermatogenesis. This is a research and development. Procedure of development is making an outline of media program, making flowchart, making story board, gathering of materials, programming and finishing. The quantitative data obtained were analyzed by descriptive statistics. Qualitative data obtained were analyzed with Miles and Huberman techniques. The instrument used is a validation sheet. The result of CD design with a Macro flash MX program shows there are 17 slides generated. This prototype obtained a valid value after a self-review technique with many revisions, especially on sound and programming. This finding suggests that process-oriented spermatogenesis can be audio-visualized into a more comprehensive form of learning media. But this interactive CD product needs further testing to determine consistency and resistance to revisions.

Higher hdl levels are a preventive factor for metabolic syndrome in obese Turkish children.

PubMed

Özer, Samet; Yılmaz, Resul; Özlem Kazanci, Nafia; Sönmezgöz, Ergün; Karaaslan, Erhan; Altuntaş, Buket; Emre Kuyucu, Yunus

2014-10-03

The definition of childhood metabolic syndrome has not been described clearly. Childhood obesity is increasing gradually, and the incidence of childhood metabolic syndrome is also rising. We aimed to show metabolic syndrome components and preventive factors for metabolic syndrome in obese children Methods: In the present study, 187 obese children and adolescents 5-18 years old were investigated retrospectively. Demographic data, anthropometric measurements, body mass index, blood pressure values, insulin levels, oral glucose tolerance test results, total cholesterol, high density lipoprotein, and triglyceride levels were obtained from hospital records. A body mass index > 95th percentile was considered obese. Insulin resistance was calculated according to the oral glucose tolerance test with 1.75 g/kg glucose maximum 75 g glucose. The insulin sensitivity index and homeostatic model assessment-insulin resistance (HOMA IR) were calculated and compared. Metabolic syndrome was diagnosed according to the modified WHO criteria adapted for metabolic syndrome in children. Abnormal glucose homeostasis was detected in 53% of subjects. Dyslipidaemia was present in 45.7% and hypertension in 16.6% of the patients. Metabolic syndrome was identified in 24.6% of obese children and adolescents. High HOMA-IR values and fasting glucose levels, elevated triglycerides and lower HDL levels were an indication of metabolic syndrome. Obesity and insulin resistance are significant factors for the development of metabolic syndrome in children and adolescents. In obese children higher HDL levels are preventive factor for metabolic syndrome. Preventing obesity and insulin resistance may decrease the prevalence of metabolic syndrome. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Delineating Bukit Bunuh impact crater boundary by geophysical and geotechnical investigation

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

Azwin, I. N., E-mail: nurazwinismail@yahoo.com; Rosli, S.; Nordiana, M. M.

2015-03-30

Evidences of crater morphology and shock metamorphism in Bukit Bunuh, Lenggong, Malaysia were found during the archaeological research conducted by the Centre for Global Archaeological Research Malaysia, Universiti Sains Malaysia. In order to register Bukit Bunuh as one of the world meteorite impact site, detailed studies are needed to verify the boundary of the crater accordingly. Geophysical study was conducted utilising the seismic refraction and 2-D electrical resistivity method. Seismic refraction survey was done using ABEM MK8 24 channel seismograph with 14Hz geophones and 40kg weight drop while 2-D electrical resistivity survey was performed using ABEM SAS4000 Terrameter and ES10-64Cmore » electrode selector with pole-dipole array. Bedrock depths were digitized from the sections obtained. The produced bedrock topography map shows that there is low bedrock level circulated by high elevated bedrock and interpreted as crater and rim respectively with diameter approximately 8km. There are also few spots of high elevated bedrock appear at the centre of the crater which interpreted as rebounds zone. Generally, the research area is divided into two layers where the first layer with velocity 400-1100 m/s and resistivity value of 10-800 Om predominantly consists of alluvium mix with gravel and boulders. Second layer represents granitic bedrock with depth of 5-50m having velocity >2100 m/s and resistivity value of >1500 Om. This research is strengthen by good correlation between geophysical data and geotechnical borehole records executed inside and outside of the crater, on the rim, as well as at the rebound area.« less

Wireless remote weather monitoring system based on MEMS technologies.

PubMed

Ma, Rong-Hua; Wang, Yu-Hsiang; Lee, Chia-Yen

2011-01-01

This study proposes a wireless remote weather monitoring system based on Micro-Electro-Mechanical Systems (MEMS) and wireless sensor network (WSN) technologies comprising sensors for the measurement of temperature, humidity, pressure, wind speed and direction, integrated on a single chip. The sensing signals are transmitted between the Octopus II-A sensor nodes using WSN technology, following amplification and analog/digital conversion (ADC). Experimental results show that the resistance of the micro temperature sensor increases linearly with input temperature, with an average TCR (temperature coefficient of resistance) value of 8.2 × 10(-4) (°C(-1)). The resistance of the pressure sensor also increases linearly with air pressure, with an average sensitivity value of 3.5 × 10(-2) (Ω/kPa). The sensitivity to humidity increases with ambient temperature due to the effect of temperature on the dielectric constant, which was determined to be 16.9, 21.4, 27.0, and 38.2 (pF/%RH) at 27 °C, 30 °C, 40 °C, and 50 °C, respectively. The velocity of airflow is obtained by summing the variations in resistor response as airflow passed over the sensors providing sensitivity of 4.2 × 10(-2), 9.2 × 10(-2), 9.7 × 10(-2) (Ω/ms(-1)) with power consumption by the heating resistor of 0.2, 0.3, and 0.5 W, respectively. The passage of air across the surface of the flow sensors prompts variations in temperature among each of the sensing resistors. Evaluating these variations in resistance caused by the temperature change enables the measurement of wind direction.

Delineating Bukit Bunuh impact crater boundary by geophysical and geotechnical investigation

NASA Astrophysics Data System (ADS)

Azwin, I. N.; Rosli, S.; Mokhtar, S.; Nordiana, M. M.; Ragu, R. R.; Mark, J.

2015-03-01

Evidences of crater morphology and shock metamorphism in Bukit Bunuh, Lenggong, Malaysia were found during the archaeological research conducted by the Centre for Global Archaeological Research Malaysia, Universiti Sains Malaysia. In order to register Bukit Bunuh as one of the world meteorite impact site, detailed studies are needed to verify the boundary of the crater accordingly. Geophysical study was conducted utilising the seismic refraction and 2-D electrical resistivity method. Seismic refraction survey was done using ABEM MK8 24 channel seismograph with 14Hz geophones and 40kg weight drop while 2-D electrical resistivity survey was performed using ABEM SAS4000 Terrameter and ES10-64C electrode selector with pole-dipole array. Bedrock depths were digitized from the sections obtained. The produced bedrock topography map shows that there is low bedrock level circulated by high elevated bedrock and interpreted as crater and rim respectively with diameter approximately 8km. There are also few spots of high elevated bedrock appear at the centre of the crater which interpreted as rebounds zone. Generally, the research area is divided into two layers where the first layer with velocity 400-1100 m/s and resistivity value of 10-800 Om predominantly consists of alluvium mix with gravel and boulders. Second layer represents granitic bedrock with depth of 5-50m having velocity >2100 m/s and resistivity value of >1500 Om. This research is strengthen by good correlation between geophysical data and geotechnical borehole records executed inside and outside of the crater, on the rim, as well as at the rebound area.

Making a Magnetorheological Fluid from Mining Tailings

NASA Astrophysics Data System (ADS)

Quitian, G.; Saldarriaga, W.; Rojas, N.

2017-12-01

We have obtained magnetite mining tailings and used it to fabricate a magnetorheological fluid (MRF). Mineralogical and morphological characteristics were determined using X-ray diffraction (XRD) and energy dispersive spectrometry (EDS), as well as size and geometry for the obtained magnetite. Finally, the fabricated MRF was rheologically characterized in a device attached to a rheometer. The application of a magnetic field of 0.12 Tesla can increase the viscosity of the MRF by more than 400 pct. A structural formation should occur within the fluid by a reordering of particles into magnetic columns, which are perpendicular to the flow direction. These structures give the fluid an increased viscosity. As the magnetic field increases, the structure formed is more resistant, resulting in an increased viscosity. One can appreciate that with a value equal to or less than 0.06 Tesla of applied magnetic field, many viscosity values associated with the work area of the oils can be achieved (0.025 and 0.34 Pa s).

Influence of drying air parameters on mass transfer characteristics of apple slices

NASA Astrophysics Data System (ADS)

Beigi, Mohsen

2016-10-01

To efficiently design both new drying process and equipment and/or to improve the existing systems, accurate values of mass transfer characteristics are necessary. The present study aimed to investigate the influence of drying air parameters (i.e. temperature, velocity and relative humidity) on effective diffusivity and convective mass transfer coefficient of apple slices. The Dincer and Dost model was used to determine the mass transfer characteristics. The obtained Biot number indicated that the moisture transfer in the apple slices was controlled by both internal and external resistance. The effective diffusivity and mass transfer coefficient values obtained to be in the ranges of 7.13 × 10-11-7.66 × 10-10 and 1.46 × 10-7-3.39 × 10-7 m s-1, respectively and the both of them increased with increasing drying air temperature and velocity, and decreasing relative humidity. The validation of the model showed that the model predicted the experimental drying curves of the samples with a good accuracy.

Game Design to Measure Reflexes and Attention Based on Biofeedback Multi-Sensor Interaction

PubMed Central

Ortiz-Vigon Uriarte, Inigo de Loyola; Garcia-Zapirain, Begonya; Garcia-Chimeno, Yolanda

2015-01-01

This paper presents a multi-sensor system for implementing biofeedback as a human-computer interaction technique in a game involving driving cars in risky situations. The sensors used are: Eye Tracker, Kinect, pulsometer, respirometer, electromiography (EMG) and galvanic skin resistance (GSR). An algorithm has been designed which gives rise to an interaction logic with the game according to the set of physiological constants obtained from the sensors. The results reflect a 72.333 response to the System Usability Scale (SUS), a significant difference of p = 0.026 in GSR values in terms of the difference between the start and end of the game, and an r = 0.659 and p = 0.008 correlation while playing with the Kinect between the breathing level and the energy and joy factor. All the sensors used had an impact on the end results, whereby none of them should be disregarded in future lines of research, even though it would be interesting to obtain separate breathing values from that of the cardio. PMID:25789493

Parameters of Transportation of Tailings of Metals Lixiviating

NASA Astrophysics Data System (ADS)

Golik, Vladimir; Dmitrak, Yury

2017-11-01

The article shows that the change in the situation in the metals market with a steady increase in production volumes is intensified against the tendency of the transition of mining production from underground mining to underground mining for a certain group of ores. The possibility of a non-waste metals extraction from not only standard, but also from substandard raw materials, is currently provided only by technology with the lixiviating of metals from developing ores. The regular dependences of the magnitude of hydraulic resistances on the hydro-mixture velocity and its density are determined. The correct values of the experimental data convergence with the calculated values of these parameters are obtained. It is shown that the optimization of the transportation parameters of lixiviating tailings allows reducing the level of chemically dangerous pollution of the environment by leachate products. The direction of obtaining the ecological and technological effect from the use of simultaneously environmental and resource-saving technology for the extraction of the disclosed metals is indicated.

Application of Vertical Electrical Sounding (VES) for the assessment of Ground Water Potential at Madi Phant, Palpa District, Western Nepal

NASA Astrophysics Data System (ADS)

Khatiwada, B.; Ghimire, H.; Bhusal, U. C.; Shrestha, S. R.; Upadhyay, K.; Khanal, A.; Pandey, D.

2017-12-01

Ground Water Resources Development Board (GWRDB), Government of Nepal, is the sole authority for systematize investigation, and management of ground water in the country. This study was conducted by GWRDB to create a data base of the groundwater potential in the hilly area. The main purpose of the study was to assess the groundwater potential at the Madi Phant Valley, Lesser Himalaya Region, Plapa District, Nepal. Data were acquired from WDJD-4 and analyzed using computer aided software called IPI2win, which yield an automatic interpretation of the apparent resistivity and data were correlated with lithologs of the vertical section. The simulated results of the ten VES points conducted using Schlumberger Configuration with AB/2 varying from 2 to 400 m and MN/2 varying from 0.5 to 50m reveal the presence of 4 to 8 geo-electric layers. Results obtained from software were rechecked by plotting the apparent resistivity value on Log-Log transparent graph sheet and manually interpreted using master curves and auxiliary curves. The resistivity values of the different layers' ranges from 3 Ωm to 3700 Ωm and were statistically analyzed from Golden Software Grapher. Representative resistivity sounding curves with modeled layer obtained after inversion was used to delineate the aquifer and 1D geoelectric sections. The geoelectrical sections for the study area consists of: the topsoil, sandy silt, sand and gravel, fractured rock and the fresh basement rock. The groundwater bearing layer of fractured rock varies between depth of 8-65 meters across foothill site (Eastern Corner) of the study area and groundwater bearing layer of sand and gravel/fractured rock varies between depth of 20-100 m in the central part of the Madi Phant valley. Contour map and 3D map of bedrock and water bearing layers for the conceptual model were prepared with the help of surfer shows that the gradient of the contour is high in the surrounding parts and flat in the center of Valley.

Genomic Prediction of Resistance to Pasteurellosis in Gilthead Sea Bream (Sparus aurata) Using 2b-RAD Sequencing

PubMed Central

Palaiokostas, Christos; Ferraresso, Serena; Franch, Rafaella; Houston, Ross D.; Bargelloni, Luca

2016-01-01

Gilthead sea bream (Sparus aurata) is a species of paramount importance to the Mediterranean aquaculture industry, with an annual production exceeding 140,000 metric tons. Pasteurellosis due to the Gram-negative bacterium Photobacterium damselae subsp. piscicida (Phdp) causes significant mortality, especially during larval and juvenile stages, and poses a serious threat to bream production. Selective breeding for improved resistance to pasteurellosis is a promising avenue for disease control, and the use of genetic markers to predict breeding values can improve the accuracy of selection, and allow accurate calculation of estimated breeding values of nonchallenged animals. In the current study, a population of 825 sea bream juveniles, originating from a factorial cross between 67 broodfish (32 sires, 35 dams), were challenged by 30 min immersion with 1 × 105 CFU virulent Phdp. Mortalities and survivors were recorded and sampled for genotyping by sequencing. The restriction-site associated DNA sequencing approach, 2b-RAD, was used to generate genome-wide single nucleotide polymorphism (SNP) genotypes for all samples. A high-density linkage map containing 12,085 SNPs grouped into 24 linkage groups (consistent with the karyotype) was constructed. The heritability of surviving days (censored data) was 0.22 (95% highest density interval: 0.11–0.36) and 0.28 (95% highest density interval: 0.17–0.4) using the pedigree and the genomic relationship matrix respectively. A genome-wide association study did not reveal individual SNPs significantly associated with resistance at a genome-wide significance level. Genomic prediction approaches were tested to investigate the potential of the SNPs obtained by 2b-RAD for estimating breeding values for resistance. The accuracy of the genomic prediction models (r = 0.38–0.46) outperformed the traditional BLUP approach based on pedigree records (r = 0.30). Overall results suggest that major quantitative trait loci affecting resistance to pasteurellosis were not present in this population, but highlight the effectiveness of 2b-RAD genotyping by sequencing for genomic selection in a mass spawning fish species. PMID:27652890

Environmental corrections of a dual-induction logging while drilling tool in vertical wells

NASA Astrophysics Data System (ADS)

Kang, Zhengming; Ke, Shizhen; Jiang, Ming; Yin, Chengfang; Li, Anzong; Li, Junjian

2018-04-01

With the development of Logging While Drilling (LWD) technology, dual-induction LWD logging is not only widely applied in deviated wells and horizontal wells, but it is used commonly in vertical wells. Accordingly, it is necessary to simulate the response of LWD tools in vertical wells for logging interpretation. In this paper, the investigation characteristics, the effects of the tool structure, skin effect and drilling environment of a dual-induction LWD tool are simulated by the three-dimensional (3D) finite element method (FEM). In order to closely simulate the actual situation, real structure of the tool is taking into account. The results demonstrate that the influence of the background value of the tool structure can be eliminated. The values of deducting the background of a tool structure and analytical solution have a quantitative agreement in homogeneous formations. The effect of measurement frequency could be effectively eliminated by chart of skin effect correction. In addition, the measurement environment, borehole size, mud resistivity, shoulder bed, layer thickness and invasion, have an effect on the true resistivity. To eliminate these effects, borehole correction charts, shoulder bed correction charts and tornado charts are computed based on real tool structure. Based on correction charts, well logging data can be corrected automatically by a suitable interpolation method, which is convenient and fast. Verified with actual logging data in vertical wells, this method could obtain the true resistivity of formation.

Three year evaluation of Xpert MTB/RIF in a low prevalence tuberculosis setting: A Scottish perspective.

PubMed

Parcell, Benjamin J; Jarchow-MacDonald, Anna A; Seagar, Amie-Louise; Laurenson, Ian F; Prescott, Gordon J; Lockhart, Michael

2017-05-01

Xpert MTB/RIF (Cepheid) is a rapid molecular assay shown to be sensitive and specific for pulmonary tuberculosis (TB) diagnosis in highly endemic countries. We evaluated its diagnostic performance in a low TB prevalence setting, examined rifampicin resistance detection and quantitative capabilities predicting graded auramine microscopy and time to positivity (TTP) of culture. Xpert MTB/RIF was used to test respiratory samples over a 3 year period. Samples underwent graded auramine microscopy, solid/liquid culture, in-house IS6110 real-time PCR, and GenoType MTBDRplus (HAIN Lifescience) to determine rifampicin and/or isoniazid resistance. A total of 2103 Xpert MTB/RIF tests were performed. Compared to culture sensitivity was 95.8%, specificity 99.5%, positive predictive value (PPV) 82.1%, and negative predictive value (NPV) 99.9%. A positive correlation was found between auramine microscopy grade and Xpert MTB/RIF assay load. We found a clear reduction in the median TTP as Xpert MTB/RIF assay load increased. Rifampicin resistance was detected. Xpert MTB/RIF was rapid and accurate in diagnosing pulmonary TB in a low prevalence area. Rapid results will influence infection prevention and control and treatment measures. The excellent NPV obtained suggests further work should be carried out to assess its role in replacing microscopy. Copyright © 2017 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Assessment of pit latrines in a peri-urban community in KwaZulu-Natal (South Africa) as a source of antibiotic resistant E. coli strains.

PubMed

Beukes, Lorika S; King, Tracy L B; Schmidt, Stefan

2017-11-01

Due to the frequent use of antibiotics and recurring illnesses related to multidrug-resistant (MDR) bacteria in South Africa, we determined if MDR Escherichia coli were present in pit latrine fecal sludge samples obtained from a peri-urban community in KwaZulu-Natal, South Africa. The abundance of E. coli in pit latrine samples was established using a most probable number (MPN) method with species confirmation done using biochemical tests and polymerase chain reaction (PCR). Forty-four randomly selected E. coli pit latrine isolates were further characterized, using the European committee on antimicrobial susceptibility testing (EUCAST) disk diffusion method to establish antibiotic resistance profiles for these E. coli isolates. The resulting MPN values for E. coli ranged from one to 6.2 log 10 MPN per gram of fresh pit latrine fecal sludge. While only 3 out of 44 E. coli pit latrine isolates showed no resistance to any of the 12 tested antibiotics, most isolates were resistant to two or more antibiotics. The majority of isolates showed resistance to at least one of the two tested aminoglycosides, one isolate showed resistance to the carbapenem ertapenem, and although resistance was not detected for tigecycline four pit latrine E. coli isolates showed intermediate resistance to this antibiotic. However, about 14% of the E. coli pit latrine isolates were categorized as MDR, all of which showed resistance to four or more antibiotics. The presence of MDR E. coli strains in pit latrine samples demonstrates that these facilities are potential sources for MDR bacteria. Copyright © 2017 Elsevier GmbH. All rights reserved.

Rifampicin treatment of canine pyoderma due to multidrug-resistant meticillin-resistant staphylococci: a retrospective study of 32 cases.

PubMed

De Lucia, Michela; Bardagi, Mar; Fabbri, Elisabetta; Ferreira, Diana; Ferrer, Lluis; Scarampella, Fabia; Zanna, Giordana; Fondati, Alessandra

2017-04-01

Rifampicin has received increased interest in veterinary dermatology because of its activity against multidrug-resistant meticillin-resistant staphylococci (MRS). There is limited knowledge about the efficacy and safety of rifampicin in dogs. To provide information on response to treatment and adverse effects in dogs treated with rifampicin for multidrug-resistant MRS pyoderma. Thirty two dogs treated with rifampicin for rifampicin-susceptible multidrug-resistant MRS pyoderma. Retrospective review of medical records, including alanine aminotransferase (ALT) and alkaline phosphatase (ALP) serum activity levels and total bilirubin concentrations, obtained before and throughout the treatment, was performed. Oral rifampicin as sole systemic antimicrobial therapy (median dose 5 mg/kg twice daily) was effective in 71.88% of cases. Topical antimicrobials were used in most cases. Median duration of rifampicin treatment was five weeks for superficial pyoderma and four weeks for deep pyoderma. Gastrointestinal signs were reported in 15% of treated dogs. Statistically significant increases of ALT (P = 0.045) and ALP (P = 0.0002) values after 3-4 weeks of treatment was observed. The median increase was equal to 0.3 and ×1.5 the upper limit of the reference ranges for ALT and ALP, respectively. Oral rifampicin combined with topical antimicrobials can be considered an effective therapeutic option for canine superficial and deep pyoderma caused by rifampicin-susceptible multidrug-resistant MRS. Liver enzyme induction might be the most important cause of ALT and ALP increase associated with rifampicin therapy in dogs. © 2016 ESVD and ACVD.

Double mutation in eleusine indica alpha-tubulin increases the resistance of transgenic maize calli to dinitroaniline and phosphorothioamidate herbicides

PubMed

Anthony; Hussey

1999-06-01

The repeated use of dinitroaniline herbicides on the cotton and soybean fields of the southern United States has resulted in the appearance of resistant biotypes of one of the world's worst weeds, Eleusine indica. Two biotypes have been characterized, a highly resistant (R) biotype and an intermediate resistant (I) biotype. In both cases the resistance has been attributed to a mutation in alpha-tubulin, a component of the alpha/beta tubulin dimer that is the major constituent of microtubules. We show here that the I-biotype mutation, like the R-biotype mutation shown in earlier work, can confer dinitroaniline resistance on transgenic maize calli. The level of resistance obtained is the same as that for E. indica I- or R-biotype seedlings. The combined I- and R-biotype mutations increase the herbicide tolerance of transgenic maize calli by a value close to the summation of the maximum herbicide tolerances of calli harbouring the single mutations. These data, taken together with the position of the two different mutations within the atomic structure of the alpha/beta tubulin dimer, imply that each mutation is likely to exert its effect by a different mechanism. These mechanisms may involve increasing the stability of microtubules against the depolymerizing effects of the herbicide or changing the conformation of the alpha/beta dimer so that herbicide binding is less effective, or a combination of both possibilities.

Comparison of microdosimetry-based absorbed doses to control tumours and clinically obtained tumour absorbed doses in treatments with ²²³Ra.

PubMed

Minguez Gabina, Pablo; Roeske, John C; Mínguez, Ricardo; Gomez de Iturriaga, Alfonso; Rodeño, Emilia

2018-06-20

We performed Monte Carlo simulations in order to determine by means of microdosimetry calculations the average number of hits to the cell nucleus required to reach a tumour control probability (TCP) of 0.9, 〈n_0.9 〉, for the source geometry of a nucleus embedded in a homogeneous distribution of ²²³Ra atoms. From the results obtained and following the MIRD methodology, we determined the values of lesion absorbed doses needed to reach a TCP of 0.9, D_0.9, for different values of mass density, cell radiosensitivity, nucleus radius and lesion volume. The greatest variation of those absorbed doses occurred with cell radiosensitivity and no dependence was found on mass density. The source geometry used was chosen because we aimed to compare the values of D_0.9 with the lesion absorbed doses obtained from image-based macrodosimetry in treatments of metastatic castration-resistant prostate cancer with ²²³Ra which were obtained assuming a homogeneous distribution of ²²³Ra atoms within the lesion. In a comparison with a study including 29 lesions, results showed that even for the case of the most radiosensitive cells simulated, 45% of the lesions treated following a schedule of two cycles of 110 kBq/kg body mass would receive absorbed doses below the values of D_0.9 determined in this study. © 2018 Institute of Physics and Engineering in Medicine.

Formation resistivity measurements from within a cased well used to quantitatively determine the amount of oil and gas present

DOEpatents

Vail, III, William Banning

2000-01-01

Methods to quantitatively determine the separate amounts of oil and gas in a geological formation adjacent to a cased well using measurements of formation resistivity. The steps include obtaining resistivity measurements from within a cased well of a given formation, obtaining the porosity, obtaining the resistivity of formation water present, computing the combined amounts of oil and gas present using Archie's Equations, determining the relative amounts of oil and gas present from measurements within a cased well, and then quantitatively determining the separate amounts of oil and gas present in the formation. Resistivity measurements are obtained from within the cased well by conducting A.C. current from within the cased well to a remote electrode at a frequency that is within the frequency range of 0.1 Hz to 20 Hz.

Genetic association analysis of ATP binding cassette protein family reveals a novel association of ABCB1 genetic variants with epilepsy risk, but not with drug-resistance.

PubMed

Balan, Shabeesh; Bharathan, Sumitha Prameela; Vellichiramal, Neetha Nanoth; Sathyan, Sanish; Joseph, Vijai; Radhakrishnan, Kurupath; Banerjee, Moinak

2014-01-01

Epilepsy constitutes a heterogeneous group of disorders that is characterized by recurrent unprovoked seizures due to widely different etiologies. Multidrug resistance remains a major issue in clinical epileptology, where one third of patients with epilepsy continue to have seizures. Role of efflux transporters in multidrug resistant epilepsy has been attributed to drug-resistant epilepsy although, with discrepant observation in genetic studies. These discrepancies could be attributed to variety of factors such as variable definition of the anti-epileptic drug (AED)-resistance, variable epilepsy phenotypes and ethnicities among the studies. In the present study we inquired the role of multidrug transporters ABCB1 and ABCG2 variants in determining AED-resistance and susceptibility to epilepsy in three well-characterized cohorts comprising of mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) (prototype for AED-resistant epilepsy); juvenile myoclonic epilepsy (JME) (prototype for AED-responsive epilepsy); and healthy non-epileptic controls, in 738 subjects of Malayalam speaking south Indian ancestry. ABCB1 and ABCG2 variants were not found to be associated with drug resistance when AED-resistant and AED-responsive cohorts were compared. However, a significant association was observed between ABCB1 (C3435T) rs1045642 and risk of having epilepsy (MTLE-HS and JME pooled cohort; genotypic p-value = 0.0002; allelic p-value = 0.004). This association was seen persistent with MTLE-HS (genotypic p-value = 0.0008; allelic p-value = 0.004) and also with JME (genotypic p-value = 0.01; allelic p-value = 0.05) cohort individually. In-silico functional prediction indicated that ABCB1 rs1045642 has a deleterious impact on protein coding function and in splicing regulation. We conclude that the ABCB1 and ABCG2 variants do not confer to AED-resistance in the study population. However, ABCB1 rs1045642 increases vulnerability to epilepsy with greater tendency for MTLE-HS in south Indian ancestry from Kerala.

Slope monitoring by using 2-D resistivity method at Sungai Batu, Pulau Pinang, Malaysia

NASA Astrophysics Data System (ADS)

Azman, Muhamad Iqbal Mubarak Faharul; Yusof, Azim Hilmy Mohd; Ismail, Nur Azwin; Ismail, Noer El Hidayah

2017-07-01

Slope is a dynamic system of geo-environmental phenomena that related to the movement of the soil and rock masses. In Pulau Pinang, the occurrence of slope related phenomena such as landslide and rock fall has become a huge issue especially during rainy season as the government would have to invest more for the people safety. 2-D resistivity method is one of the geophysical methods that can be applied to overcome this issue thus prepare countermeasure actions. Monitoring is one of the common acquisition technique that has been used in solving such issue. This technique was applied to identify and monitor changes at the suspected area and thus, countermeasure steps can be taken accordingly and not blindfolded. Starting from August until November 2016, a 200 m survey line of 2-D resistivity survey had been conducted monthly at Sungai Batu, Pulau Pinang slope for monitoring purpose. Three resistivity ranges were able to detect within the subsurface. Resistivity value of 250 - 400 Ωm indicated the low resistivity value and interpreted as the weak zone located at distance of 90 - 120 m with depth of 10 m. Intermediate resistivity value was interpreted as weathered granite zone with resistivity value of 400 - 1500 Ωm was found at almost along survey line. High resistivity value was > 5000 Ωm and interpreted as granitic bedrock located at depth of > 20 m. Aside from weathered granite zone and weak zone, a fracture was found develop over time at distance of 130 - 140 m. The features found have the potential to be the cause for slope failure phenomena to occur. As a conclusion, monitoring slope using 2-D resistivity method is a success and indeed helpful in overcome landslide and rock fall issue as a pre-countermeasure action.

The hydrogeological conditions in Sahel Hasheesh, Eastern Desert, Eg

NASA Astrophysics Data System (ADS)

Abdalla, Mohamed A.; Mekhemer, Hatem M.; Mabrou, Walid Abdallah

2016-06-01

The groundwater development in Egypt in the present time is of a vital importance than in past few years. A comprehensive plan for new land reclamation projects has been recently established. To achieve these plans new sources of water must be available. This has been done by conducting a number of VES'S where interpreted by a comparison with the existing drilled borehole soil samples. The optimum resistivity model is obtained by matching method using "IPI2Win" Moscow State University 2000 software computer programs for resistivity interpretation. The results of the quantitative interpretation of the resistivity curves has been represented as geoelectric sections, showing the thickness and true electric resistivity values of the different geoelectric layers. The results of quantitative interpretation of the vertical electrical soundings show subsurface five geoelectric units and the aquifer system belongs to lower Miocene and the total salinity of 2451.2 ppm. The depth to water surface is 88.05 m and the total dissolved solids are 2451.2 ppm (Mekhemer well). The salt assemblages in Sahel Hasheesh are NaCl, MgCl2, MgSO4, CaSO4, Ca(HCO3)2. This marine water is of brackish sodium chloride water type (NaCl).

Influence of Blended Cements with Calcareous Fly Ash on Chloride Ion Migration and Carbonation Resistance of Concrete for Durable Structures.

PubMed

Glinicki, Michał A; Jóźwiak-Niedźwiedzka, Daria; Gibas, Karolina; Dąbrowski, Mariusz

2016-01-02

The objective of this paper is to examine the possible use of new blended cements containing calcareous fly ash in structural concrete, potentially adequate for structural elements of nuclear power plants. The investigation included five new cements made with different contents of non-clinker constituents: calcareous fly ash, siliceous fly ash, ground granulated blastfurnace slag, and a reference cement-ordinary Portland cement. The influence of innovative cements on the resistance of concrete to chloride and carbonation exposure was studied. Additionally, an evaluation of the microstructure was performed using optical microscopy on concrete thin sections. Test results revealed a substantial improvement of the resistance to chloride ion penetration into concrete containing blended cements. The resistance was higher for increased clinker replacement levels and increased with curing time. However, concrete made with blended cements exhibited higher depth of carbonation than the Portland cement concrete, except the Portland-fly ash cement with 14.3% of calcareous fly ash. The thin sections analysis confirmed the values of the carbonation depth obtained from the phenolphthalein test. Test results indicate the possible range of application for new cements containing calcareous fly ash.

Influence of Blended Cements with Calcareous Fly Ash on Chloride Ion Migration and Carbonation Resistance of Concrete for Durable Structures

PubMed Central

Glinicki, Michał A.; Jóźwiak-Niedźwiedzka, Daria; Gibas, Karolina; Dąbrowski, Mariusz

2016-01-01

The objective of this paper is to examine the possible use of new blended cements containing calcareous fly ash in structural concrete, potentially adequate for structural elements of nuclear power plants. The investigation included five new cements made with different contents of non-clinker constituents: calcareous fly ash, siliceous fly ash, ground granulated blastfurnace slag, and a reference cement—ordinary Portland cement. The influence of innovative cements on the resistance of concrete to chloride and carbonation exposure was studied. Additionally, an evaluation of the microstructure was performed using optical microscopy on concrete thin sections. Test results revealed a substantial improvement of the resistance to chloride ion penetration into concrete containing blended cements. The resistance was higher for increased clinker replacement levels and increased with curing time. However, concrete made with blended cements exhibited higher depth of carbonation than the Portland cement concrete, except the Portland-fly ash cement with 14.3% of calcareous fly ash. The thin sections analysis confirmed the values of the carbonation depth obtained from the phenolphthalein test. Test results indicate the possible range of application for new cements containing calcareous fly ash. PMID:28787821

A graphene-based non-volatile memory

NASA Astrophysics Data System (ADS)

Loisel, Loïc.; Maurice, Ange; Lebental, Bérengère; Vezzoli, Stefano; Cojocaru, Costel-Sorin; Tay, Beng Kang

2015-09-01

We report on the development and characterization of a simple two-terminal non-volatile graphene switch. After an initial electroforming step during which Joule heating leads to the formation of a nano-gap impeding the current flow, the devices can be switched reversibly between two well-separated resistance states. To do so, either voltage sweeps or pulses can be used, with the condition that VSET < VRESET , where SET is the process decreasing the resistance and RESET the process increasing the resistance. We achieve reversible switching on more than 100 cycles with resistance ratio values of 104. This approach of graphene memory is competitive as compared to other graphene approaches such as redox of graphene oxide, or electro-mechanical switches with suspended graphene. We suggest a switching model based on a planar electro-mechanical switch, whereby electrostatic, elastic and friction forces are competing to switch devices ON and OFF, and the stability in the ON state is achieved by the formation of covalent bonds between the two stretched sides of the graphene, hence bridging the nano-gap. Developing a planar electro-mechanical switch enables to obtain the advantages of electro-mechanical switches while avoiding most of their drawbacks.

Resistance of Bacteroides isolates recovered among clinical samples from a major Costa Rican hospital between 2000 and 2008 to ß-lactams, clindamycin, metronidazole, and chloramphenicol.

PubMed

Cordero-Laurent, E; Rodríguez, C; Rodríguez-Cavallini, E; Gamboa-Coronado, M M; Quesada-Gómez, C

2012-12-01

To assess the susceptibility of 100 isolates of Bacteroides spp. recovered in a major Costa Rican hospital between 2000 and 2008 to several ß-lactams, chloramphenicol, clindamycin and metronidazole. Susceptibility to amoxicillin, amoxicillin with clavulanic acid, piperacillin, piperacillin with tazobactam, ticarcillin, ticarcillin with clavulanic acid, cefoxitin, cefotetan, imipenem, chloramphenicol, clindamycin, and metronidazole was determined with the ATB ANA® system. In addition, minimum inhibitory concentrations (MIC) of clindamycin and metronidazole were determined with the broth microdilution method because these drugs are the treatment of choice for anaerobic infections in Costa Rica. Reference strains ATCC® 25285 and ATCC® 29741 were employed as indicated. According to the ATB ANA® system, 93 isolates were resistant to at least one antibiotic. Resistance to ß-lactams was common. By contrast, resistance to ß-lactams supplemented with ß-lactamase inhibitors was rare. All of the strains were inhibited by imipenem and chloramphenicol. By a broth microdilución test, resistance to clindamycin was 20%, with MIC ranging from 64 mg/L to 256 mg/L; all of the strains were susceptible to metronidazole. The high MIC for clindamycin obtained for the majority of the resistant strains is highly suggestive of the presence of mechanisms of acquired resistance among the isolates, therefore surveillance studies are required to determine its efficacy. The low resistance to metronidazole observed underlines its value as a first-line drug. On the other hand, imipenem could be used to treat infections that do not respond well to metronidazole or clindamycin.

Interfacial layer thickness dependent electrical characteristics of Au/(Zn-doped PVA)/n-4H-SiC (MPS) structures at room temperature

NASA Astrophysics Data System (ADS)

Lapa, Havva Elif; Kökce, Ali; Al-Dharob, Mohammed; Orak, İkram; Özdemir, Ahmet Faruk; Altındal, Semsettin

2017-10-01

Au/(Zn-doped PVA)/n-4H-SiC metal/polymer/semiconductor (MPS) structures with different interfacial layer thickness values (50, 150, 500 nm) were fabricated and their electrical characteristics were compared. Their electrical parameters (i.e. reverse-bias saturation current (Io), ideality factor (n), zero-bias barrier height (BH) (Φbo), series and shunt resistances (Rs, Rsh)) were calculated from the forward bias current-voltage (IF-VF) data whereas other parameters (i.e. Fermi energy level (EF), BH (Vb) and donor concentration (Nd)) were calculated from the linear part of C-2-V characteristics at room temperature. Obtained results confirmed that the values of n, Φbo, Rs and Rsh increase with increasing interlayer thickness, and linear correlation between n and Φbo was observed. The high values of n for three structures can be ascribed to the presence of an interlayer, surface states (Nss) and barrier inhomogeneities. The energy density distribution profile of Nss was obtained from the IF-VF data by taking into account voltage-dependent effective BH (Ve) and n for each structure. The Ri vs V plot for these structures was obtained using both Ohm's law and Nicollian-Brews method. All these experimental results show that the interfacial layer and its thickness play an important role in main electric parameters of these structures.

Slope failures evaluation and landslides investigation using 2-D resistivity method

NASA Astrophysics Data System (ADS)

Nordiana, M. M.; Azwin, I. N.; Nawawi, M. N. M.; Khalil, A. E.

2018-06-01

Slope failure is a complex phenomenon that may caused to landslides. Buildings and infrastructure such as transportation facilities and pipelines located within the boundaries of a landslide can be damaged or destroyed. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. Six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed. The data were processed using Res2Dinv and surfer10 software to evaluate the subsurface characteristics. The 2-D resistivity results show that the subsurface consist of two main zones. The first zone was alluvium or highly weathered with resistivity value of 100-1000 Ω m and depth of >30 m. This zone consists of saturated area with resistivity value of 1-100 Ω m and boulders with resistivity value of 1200-7000 Ω m. The second zone with resistivity value of >7000 Ω m was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. This will cause to low strength of soil, debris flow and movement of earth. On the basis of the case examples described, 2-D resistivity method is categorized into desirable and useful method in determination of slope failure and future assessments.

Stainless steels for cryogenic bolts and nuts (in French)

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

Leroy, F.; Rabbe, P.; Odin, G.

1975-03-01

Stainless steel for cryogenic applications are generally austenitic steels which, under the effect of cold-drawing, can or cannot undergo a partial martensitic transformation according to their composition. It has been shown that very high ductility and endurance characteristics at low temperatures, together with very high yield strength and resistances values, can be attained with grades of nitrogenous steels of types Z2CN18-10N and Z3CMN18-8-6N. Optimum ductility values are obtained by employing to the best possible, the martensitic transformations which develop during cold-drawing. From the plotting of the rational traction curves, it is possible to analyse very simply the influence of themore » composition on the martensitic transformations. (FR)« less

Enhancement of electrical properties in polycrystalline BiFeO3 thin films

NASA Astrophysics Data System (ADS)

Yun, Kwi Young; Ricinschi, Dan; Kanashima, Takeshi; Okuyama, Masanori

2006-11-01

Ferroelectric BiFeO3 thin films were grown on Pt /TiO2/SiO2/Si substrates by pulsed-laser deposition. From the x-ray diffraction analysis, the BiFeO3 thin films consist of perovskite single phase, and the crystal structure shows the tetragonal structure with a space group P4mm. The BiFeO3 thin films show enhanced electrical properties with low leakage current density value of ˜10-4A /cm2 at a maximum applied voltage of 31V. This enhanced electrical resistivity allowed the authors to obtain giant ferroelectric polarization values such as saturation polarizations of 110 and 166μC/cm2 at room temperature and 80K, respectively.

Development of fly ash boards with thermal, acoustic and fire insulation properties.

PubMed

Leiva, C; Arenas, C; Vilches, L F; Alonso-Fariñas, B; Rodriguez-Galán, M

2015-12-01

This paper presents an experimental analysis on a new board composed of gypsum and fly ashes from coal combustion, which are mutually compatible. Physical and mechanical properties, sound absorption coefficient, thermal properties and leaching test have been obtained. The mechanical properties showed similar values to other commercial products. As far as the acoustic insulation characteristics are concerned, sound absorption coefficients of 0.3 and 0.8 were found. The board presents a low thermal conductivity and a fire resistance higher than 50 min (for 4 cm of thickness). The leaching of trace elements was below the leaching limit values. These boards can be considered as suitable to be used in building applications as partitions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analysis of a model race car

NASA Astrophysics Data System (ADS)

Coletta, Vincent P.; Evans, Jonathan

2008-10-01

We analyze the motion of a gravity powered model race car on a downhill track of variable slope. Using a simple algebraic function to approximate the height of the track as a function of the distance along the track, and taking account of the rotational energy of the wheels, rolling friction, and air resistance, we obtain analytic expressions for the velocity and time of the car as functions of the distance traveled along the track. Photogates are used to measure the time at selected points along the track, and the measured values are in excellent agreement with the values predicted from theory. The design and analysis of model race cars provides a good application of principles of mechanics and suggests interesting projects for classes in introductory and intermediate mechanics.

[Molecular epidemiologic study on Mycobacterium tuberculosis from drug resistance monitoring sites of Guangdong Province, 2015].

PubMed

Huang, X C; Guo, H X; Wu, Z H; Guo, C X; Wei, W J; Li, H C; Sun, Q; Zhang, C C; Li, Z Y; Chen, T; Zhong, Q; Zhou, L

2017-05-12

Objective: To understand the characteristics of Mycobacterium tuberculosis (MTB) in epidemiology and distribution from Guangdong Province, and to explore the risk factors associated with drug resistance. Methods: A total of 225 clinical strains of MTB collected from 5 drug resistance monitoring sites of Guangdong Province in 2015 were tested by Regions of Difference 105 (RD105) deletion test and 15 loci mycobacterial interspersed repetitive units (MIRU) were used for genotyping. Gene clustering was analyzed using BioNumerics7.6. Drug susceptibility test was tested by proportion method. The statistical analysis used chi-square test and multivariate logistic regression. Results: There were 158 (70.2%) Beijing family strains from the 225 cases. Hunter-gaston index of MIRU loci varied from each other. The MTBs from Guangdong Province were categorized into 2 gene clusters by clustering analysis in which the rate of cluster of complexⅠwas significantly higher than complexⅡ(χ(2) values were 9.331, P values were 0.020). It was found by multivariate logistic regression that Qub11b was associated with resistance to rifampicin and isoniazid ( P values were 0.013, 0.012 respectively.), ETR F with resistance to isoniazid, streptomycin, ethambutol and ofloxacin ( P values were 0.039, 0.040, 0.023 and 0.003 respectively), Mtub21 with resistance to capreomycin ( P values were 0.040), and QUB26 with resistance to ethionamide ( P values were 0.047). Conclusions: The genes of MTB from Guangdong Province were of polymorphisms and the distribution of strains were stable. QUB11b, ETR F, Mtub21 and QUB26 could be related to biomarkers for predicting drug resistance.

Cytotoxic, Virucidal, and Antiviral Activity of South American Plant and Algae Extracts

PubMed Central

Faral-Tello, Paula; Mirazo, Santiago; Dutra, Carmelo; Pérez, Andrés; Geis-Asteggiante, Lucía; Frabasile, Sandra; Koncke, Elina; Davyt, Danilo; Cavallaro, Lucía; Heinzen, Horacio; Arbiza, Juan

2012-01-01

Herpes simplex virus type 1 (HSV-1) infection has a prevalence of 70% in the human population. Treatment is based on acyclovir, valacyclovir, and foscarnet, three drugs that share the same mechanism of action and of which resistant strains have been isolated from patients. In this aspect, innovative drug therapies are required. Natural products offer unlimited opportunities for the discovery of antiviral compounds. In this study, 28 extracts corresponding to 24 plant species and 4 alga species were assayed in vitro to detect antiviral activity against HSV-1. Six of the methanolic extracts inactivated viral particles by direct interaction and 14 presented antiviral activity when incubated with cells already infected. Most interesting antiviral activity values obtained are those of Limonium brasiliense, Psidium guajava, and Phyllanthus niruri, which inhibit HSV-1 replication in vitro with 50% effective concentration (EC50) values of 185, 118, and 60 μg/mL, respectively. For these extracts toxicity values were calculated and therefore selectivity indexes (SI) obtained. Further characterization of the bioactive components of antiviral plants will pave the way for the discovery of new compounds against HSV-1. PMID:22619617

Chemometrical assessment of the electrical parameters obtained by long-term operating freshwater sediment microbial fuel cells.

PubMed

Mitov, Mario; Bardarov, Ivo; Mandjukov, Petko; Hubenova, Yolina

2015-12-01

The electrical parameters of nine freshwater sediment microbial fuel cells (SMFCs) were monitored for a period of over 20 months. The developed SMFCs, divided into three groups, were started up and continuously operated under different constant loads (100, 510 and 1100 Ω) for 2.5 months. At this stage of the experiment, the highest power density values, reaching 1.2 ± 0.2 mW/m(2), were achieved by the SMFCs loaded with 510 Ω. The maximum power obtained at periodical polarization during the rest period, however, ranged between 26.2 ± 2.8 and 35.3 ± 2.8 mW/m(2), strongly depending on the internal cell resistance. The statistical evaluation of data derived from the polarization curves shows that after 300 days of operation all examined SMFCs reached a steady-state and the system might be assumed as homoscedastic. The estimated values of standard and expanded uncertainties of the electric parameters indicate a high repeatability and reproducibility of the SMFCs' performance. Results obtained in subsequent discharge-recovery cycles reveal the opportunity for practical application of studied SMFCs as autonomous power sources.

Effect of High Strain-Rate Deformation and Aging Temperature on the Evolution of Structure, Microhardness, and Wear Resistance of Low-Alloyed Cu-Cr-Zr Alloy

NASA Astrophysics Data System (ADS)

Kheifets, A. E.; Khomskaya, I. V.; Korshunov, L. G.; Zel'dovich, V. I.; Frolova, N. Yu.

2018-04-01

The effect of the preliminary high strain-rate deformation, performed via the method of dynamic channel-angular pressing (DCAP), and subsequent annealings on the tribological properties of a dispersionhardened Cu-0.092 wt % Cr-0.086 wt % Zr alloy has been investigated. It has been shown that the surfacelayer material of the alloy with a submicrocrystalline (SMC) structure obtained by the DCAP method can be strengthened using severe plastic deformation by sliding friction at the expense of creating a nanocrystalline structure with crystallites of 15-60 nm in size. It has been shown that the SMC structure obtained by the high strain-rate DCAP deformation decreases the wear rate of the samples upon sliding friction by a factor of 1.4 compared to the initial coarse-grained state. The maximum values of the microhardness and minimum values of the coefficient of friction and shear strength have been obtained in the samples preliminarily subjected to DCAP and aging at 400°C. The attained level of microhardness is 3350 MPa, which exceeds the microhardness of the alloy in the initial coarse-grained state by five times.

Ultra-low Temperature Curable Conductive Silver Adhesive with different Resin Matrix

NASA Astrophysics Data System (ADS)

Zhou, Xingli; Wang, Likun; Liao, Qingwei; Yan, Chao; Li, Xing; Qin, Lei

2018-03-01

The ultra-low temperature curable conductive silver adhesive with curing temperature less than 100 °C needed urgently for the surface conductive treatment of piezoelectric composite material due to the low thermal resistance of composite material and low adhesion strength of adhesive. An ultra-low temperature curable conductive adhesive with high adhesion strength was obtained for the applications of piezoelectric composite material. The microstructure, conductive properties and adhesive properties with different resin matrix were investigated. The conductive adhesive with AG-80 as the resin matrix has the shorter curing time (20min), lower curing temperature (90°C) and higher adhesion strength (7.6MPa). The resistivity of AG-80 sample has the lower value (2.13 × 10-4Ω·cm) than the 618 sample (4.44 × 10-4Ω·cm).

The properties of plasma-enhanced atomic layer deposition (ALD) ZnO thin films and comparison with thermal ALD

NASA Astrophysics Data System (ADS)

Kim, Doyoung; Kang, Hyemin; Kim, Jae-Min; Kim, Hyungjun

2011-02-01

Zinc oxide (ZnO) thin films were prepared by plasma-enhanced atomic layer deposition (PE-ALD) using oxygen plasma as a reactant and the properties were compared with those of thermal atomic layer deposition (TH-ALD) ZnO thin films. While hexagonal wurzite phase with preferential (0 0 2) orientation was obtained for both cases, significant differences were observed in various aspects of film properties including resistivity values between these two techniques. Photoluminescence (PL) measurements have shown that high resistivity of PE-ALD ZnO thin films is due to the oxygen interstitials at low growth temperature of 200 °C, whose amount decreases with increasing growth temperature. Thin film transistors (TFT) using TH- and PE-ALD ZnO as an active layer were also fabricated and the device properties were evaluated comparatively.

TlCaBaCuO high Tc superconducting microstrip ring resonators designed for 12 GHz

NASA Technical Reports Server (NTRS)

Subramanyam, G.; Kapoor, V. J.; Chorey, C. M.; Bhasin, K. B.

1993-01-01

Microwave properties of sputtered Tl-Ca-Ba-Cu-O thin films were investigated by designing, fabricating, and testing microstrip ring resonators. Ring resonators designed for 12 GHz fundamental resonance frequency, were fabricated and tested. From the unloaded Q values for the resonators, the surface resistance was calculated by separating the conductor losses from the total losses. The penetration depth was obtained from the temperature dependence of resonance frequency, assuming that the shift in resonance frequency is mainly due to the temperature dependence of penetration depth. The effective surface resistance at 12 GHz and 77 K was determined to be between 1.5 and 2.75 mOmega, almost an order lower than Cu at the same temperature and frequency. The effective penetration depth at 0 K is approximately 7000 A.

Insecticide susceptibility and dengue vector status of wild Stegomyia albopicta in a strategically important area of Assam, India

PubMed Central

2014-01-01

Background Dengue vector control programmes are facing operational challenges due to resistance against commonly used insecticides throughout the endemic countries. Recently, there has been appreciable increase in the dengue cases in India, however, no recent data are available on susceptible status of dengue vectors. We have studied the susceptibility level of St. albopicta to commonly used insecticides in India. Adult mosquitoes were tested for the presence of dengue virus. Methods St. albopicta larval bioassays were carried out to determine the lethal concentrations (LC10, LC50 and LC99) and the resistance ratios (RR10, RR50 and RR99) for temephos. Susceptibility to 4% DDT, 0.05% deltamethrin and 5% malathion was assessed following standard procedure. Knock-down times (KDT10, KDT50 and KDT99) were estimated and knock-down resistance ratios (KRR10, KRR50 and KRR99) were calculated. VectorTest™ dengue antigen assay was used to detect the dengue virus in the field collected mosquitoes. Results In larval bioassays, the RR ranged from 1.4 (for RR99) to 1.7 (for RR50), which suggested that the tested St. albopicta were susceptible to temephos. There was no deviation among the lethal concentration data from linearity (r2 = 0.61). Adult St. albopicta mosquitoes were resistant to DDT, while fully susceptible to deltamethrin and malathion. The knock-down values (KDT10, KDT50 and KDT99) obtained for DDT displayed straight line in log-dose-probit analysis and follow linear regression model. The KRR99 for DDT was 4.9, which indicated a 4.9 folds increase in knock-down resistance to DDT. However, for malathion and deltamethrin, the KRR99 values were 1.6 and 1.5 respectively suggesting that mosquitoes were knock-down sensitive. None of the mosquito pool was dengue virus positive. Conclusion St. albopicta showed resistance to DDT and reduced sensitivity to deltamethrin and malathion. This data on insecticide resistance could help public health authorities in India to design more effective vector control measures. More dengue vector specimens need to be scanned to identify the potential dengue vector. PMID:24981885

Artemisinin resistance without pfkelch13 mutations in Plasmodium falciparum isolates from Cambodia.

PubMed

Mukherjee, Angana; Bopp, Selina; Magistrado, Pamela; Wong, Wesley; Daniels, Rachel; Demas, Allison; Schaffner, Stephen; Amaratunga, Chanaki; Lim, Pharath; Dhorda, Mehul; Miotto, Olivo; Woodrow, Charles; Ashley, Elizabeth A; Dondorp, Arjen M; White, Nicholas J; Wirth, Dyann; Fairhurst, Rick; Volkman, Sarah K

2017-05-12

Artemisinin resistance is associated with delayed parasite clearance half-life in vivo and correlates with ring-stage survival under dihydroartemisinin in vitro. Both phenotypes are associated with mutations in the PF3D7_1343700 pfkelch13 gene. Recent spread of artemisinin resistance and emerging piperaquine resistance in Southeast Asia show that artemisinin combination therapy, such as dihydroartemisinin-piperaquine, are losing clinical effectiveness, prompting investigation of drug resistance mechanisms and development of strategies to surmount emerging anti-malarial resistance. Sixty-eight parasites isolates with in vivo clearance data were obtained from two Tracking Resistance to Artemisinin Collaboration study sites in Cambodia, culture-adapted, and genotyped for pfkelch13 and other mutations including pfmdr1 copy number; and the RSA 0-3h survival rates and response to antimalarial drugs in vitro were measured for 36 of these isolates. Among these 36 parasites one isolate demonstrated increased ring-stage survival for a PfKelch13 mutation (D584V, RSA 0-3h  = 8%), previously associated with slow clearance but not yet tested in vitro. Several parasites exhibited increased ring-stage survival, yet lack pfkelch13 mutations, and one isolate showed evidence for piperaquine resistance. This study of 68 culture-adapted Plasmodium falciparum clinical isolates from Cambodia with known clearance values, associated the D584V PfKelch13 mutation with increased ring-stage survival and identified parasites that lack pfkelch13 mutations yet exhibit increased ring-stage survival. These data suggest mutations other than those found in pfkelch13 may be involved in conferring artemisinin resistance in P. falciparum. Piperaquine resistance was also detected among the same Cambodian samples, consistent with reports of emerging piperaquine resistance in the field. These culture-adapted parasites permit further investigation of mechanisms of both artemisinin and piperaquine resistance and development of strategies to prevent or overcome anti-malarial resistance.

The cutoff values of indirect indices for measuring insulin resistance for metabolic syndrome in Korean children and adolescents.

PubMed

Kim, Jun Woo; Park, Sang Hoo; Kim, Yoojin; Im, Minji; Han, Heon-Seok

2016-09-01

The prevalence rates of metabolic syndrome (MetS) and percentile distribution of insulin resistance (IR) among Korean children and adolescents were investigated. The cutoff values of IR were calculated to identify high-risk MetS groups. Data from 3,313 Korean subjects (1,756 boys and 1,557 girls, aged 10-18 years) were included from the Korean National Health and Nutrition Examination Survey conducted during 2007-2010. Three different sets of criteria for MetS were used. Indirect measures of IR were homeostasis model assessment (HOMA-IR) and triglyceride and glucose (TyG) index. The cutoff values of the HOMA-IR and TyG index were obtained from the receiver operation characteristic curves. According to the MetS criteria of de Ferranti el al., Cook et al., and the International Diabetes Federation, the prevalence rates in males and females were 13.9% and 12.3%, 4.6% and 3.6%, and 1.4% and 1.8%, respectively. Uses these 3 criteria, the cutoff values of the HOMA-IR and TyG index were 2.94 and 8.41, 3.29 and 8.38, and 3.54 and 8.66, respectively. The cutoff values using each of the 3 criteria approximately corresponds to the 50th-75th, 75th, and 75th-90th percentiles of normal HOMA-IR and TyG index levels. This study describes the prevalence rates of MetS in Korean children and adolescents, an index of IR, and the cutoff values for MetS with the aim of detecting high-risk groups. The usefulness of these criteria needs to be verified by further evaluation.

Transfer factor, lung volumes, resistance and ventilation distribution in healthy adults.

PubMed

Verbanck, Sylvia; Van Muylem, Alain; Schuermans, Daniel; Bautmans, Ivan; Thompson, Bruce; Vincken, Walter

2016-01-01

Monitoring of chronic lung disease requires reference values of lung function indices, including putative markers of small airway function, spanning a wide age range.We measured spirometry, transfer factor of the lung for carbon monoxide (TLCO), static lung volume, resistance and ventilation distribution in a healthy population, studying at least 20 subjects per sex and per decade between the ages of 20 and 80 years.With respect to the Global Lung Function Initiative reference data, our subjects had average z-scores for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC of -0.12, 0.04 and -0.32, respectively. Reference equations were obtained which could account for a potential dependence of index variability on age and height. This was done for (but not limited to) indices that are pertinent to asthma and chronic obstructive pulmonary disease studies: forced expired volume in 6 s, forced expiratory flow, TLCO, specific airway conductance, residual volume (RV)/total lung capacity (TLC), and ventilation heterogeneity in acinar and conductive lung zones.Deterioration in acinar ventilation heterogeneity and lung clearance index with age were more marked beyond 60 years, and conductive ventilation heterogeneity showed the greatest increase in variability with age. The most clinically relevant deviation from published reference values concerned RV/TLC values, which were considerably smaller than American Thoracic Society/European Respiratory Society-endorsed reference values. Copyright ©ERS 2016.

Drug resistance in Mexico: results from the National Survey on Drug-Resistant Tuberculosis.

PubMed

Bojorquez-Chapela, I; Bäcker, C E; Orejel, I; López, A; Díaz-Quiñonez, A; Hernández-Serrato, M I; Balandrano, S; Romero, M; Téllez-Rojo Solís, M M; Castellanos, M; Alpuche, C; Hernández-Ávila, M; López-Gatell, H

2013-04-01

To present estimations obtained from a population-level survey conducted in Mexico of prevalence rates of mono-, poly- and multidrug-resistant strains among newly diagnosed cases of pulmonary tuberculosis (TB), as well as the main factors associated with multidrug resistance (combined resistance to isoniazid and rifampicin). Study data came from the National Survey on TB Drug Resistance (ENTB-2008), a nationally representative survey conducted during 2008-2009 in nine states with a stratified cluster sampling design. Samples were obtained for all newly diagnosed cases of pulmonary TB in selected sites. Drug susceptibility testing (DST) was performed for anti-tuberculosis drugs. DST results were obtained for 75% of the cases. Of these, 82.2% (95%CI 79.5-84.7) were susceptible to all drugs. The prevalence of multidrug-resistant TB (MDR-TB) was estimated at 2.8% (95%CI 1.9-4.0). MDR-TB was associated with previous treatment (OR 3.3, 95%CI 1.1-9.4). The prevalence of drug resistance is relatively low in Mexico. ENTB-2008 can be used as a baseline for future follow-up of drug resistance.

Vortex-glass state in the isovalent optimally doped pnictide superconductor BaFe2(As0.68P0.32)2

NASA Astrophysics Data System (ADS)

Salem-Sugui, S., Jr.; Mosqueira, J.; Alvarenga, A. D.; Sóñora, D.; Crisan, A.; Ionescu, A. M.; Sundar, S.; Hu, D.; Li, S.-L.; Luo, H.-Q.

2017-05-01

We report on isochamp magneto-resistivity and ac susceptibility curves obtained in a high-quality single crystal of the isovalent optimally doped pnictide BaFe2(As{}0.68P{}0.32)2 with superconducting temperature T c = 27.8 K for H∥c-axis. Plots of the logarithmic derivative of the resistivity curves allowed the identification of a vortex-glass (VG) phase and to obtain the values of the critical glass temperature T g, the temperature T * marking the transition to the liquid phase and of the critical exponent s. The presence of the VG phase is confirmed by detailed measurements of the third harmonic signal of the ac magnetic susceptibility. The modified VG model was successfully applied to the data allowing the obtention of the temperature independent VG activation energy U b . The activation energy U 0 obtained from the Arrhenius plots in the flux-flow region are compared with U b and with U 0 obtained from flux-creep measurements on a M(H) isothermal in the same sample. A phase diagram of the studied sample is constructed showing the T g glass line, the T * line representing a transition (melting) to the liquid phase, the mean field temperature T c(H) line and the H p line obtained from the peaks in isothermal critical current, J c(H) curves, which are explained in terms of a softening of the vortex lattice. The glass line was fitted by a theory presented in the literature which considers the effect of disorder.

Isolation and characterization of an IGROV-1 human ovarian cancer cell line made resistant to Ecteinascidin-743 (ET-743)

PubMed Central

Erba, E; Bergamaschi, D; Bassano, L; Ronzoni, S; Liberti, G Di; Muradore, I; Vignati, S; Faircloth, G; Jimeno, J; D'Incalci, M

2000-01-01

By exposing Igrov-1 human ovarian cancer cells to increasing concentrations of Ecteinascidin-743 (ET-743), either for a short or prolonged time, we obtained sublines resistant to ET-743 which overexpress Pgp. The most resistant clone (Igrov-1/25 ET) was evaluated for biological and pharmacological characterizations. The increased Pgp levels of Igrov-1/25 ET were not due to amplification of the mdr-1 gene but to increased mRNA levels. No increase in other multidrug resistance-related proteins such as MRP or LRP was observed in Igrov-1/25 ET. The IC50values of ET-743 against Igrov-1/25 ET was approximately 50 times higher than the parental cell line. Resistance was not reversed while maintaining the cell line in drug-free medium for at least 24 months. Igrov-1/25 ET was cross-resistant to Doxorubicin and VP16 while it was equally sensitive to L-PAM, MNNG, CPT and only marginally less sensitive to Cis-DDP and Oxaliplatin compared to the parental cell line. Igrov-1/25 ET exposed to Doxorubicin retained this drug much less, mainly because of a more efficient drug efflux. The cyclosporine analogue SDZ PSC-833 reversed the resistance of Igrov-1/25 ET to ET-743, without any enhancement of the drug activity against the parental Igrov-1 cell line. Igrov-1/25 ET exhibits typical features of cell lines overexpressing the mdr-1 gene and can be a potentially useful tool in selecting ET-743 non-cross-resistant analogues as well as to investigate methods to counteract resistance to this drug. © 2000 Cancer Research Campaign PMID:10817511

Comparative effects of single-dose ceftriaxone versus three oral antibiotic regimens on stool colonization by resistant bacilli in children.

PubMed

Toltzis, Philip; Dul, Michael; O'Riordan, Mary Ann; Toltzis, Hasida; Blumer, Jeffrey L

2007-01-01

The use of short-term intramuscular ceftriaxone for pediatric ambulatory conditions raises concerns regarding the promotion of resistance among colonizing enteric bacteria. This study was designed to assess the prevalence of stool colonization with resistant Gram-negative bacilli after single-dose ceftriaxone treatment compared with other regimens for acute otitis media. Children age 3 months to 7 years and diagnosed with acute otitis media were randomized to receive treatment with single-dose ceftriaxone or with oral cefprozil, amoxicillin or azithromycin. Stool samples were obtained at enrollment and then 3-5 days, 10-14 days, and 28-30 days after therapy was initiated and screened for the presence of facultative Gram-negative bacilli resistant to ceftriaxone, cefprozil, amoxicillin, piperacillin, piperacillin-tazobactam and tobramycin. Mean prevalence of colonization by resistant organisms for each treatment group was compared at each time point. One thousand nine subjects were enrolled. The prevalence of colonization by a Gram-negative bacillus resistant to at least 1 of the screening antibiotics decreased after receipt of ceftriaxone but returned close to values measured at study entry by 30 days. A qualitatively similar pattern was noted for the 3 other regimens, but a quantitatively greater decrease in the prevalence of colonization by a resistant bacterium was noted at the 3- to 5-day and 10- to 14-day visits among azithromycin recipients (P < 0.001). Colonization by a Gram-negative bacillus resistant specifically to ceftriaxone was unusual at each study visit, regardless of treatment assignment. A single intramuscular dose of ceftriaxone had a similar effect on the prevalence of antibiotic-resistant Gram-negative facultative bacilli in the stool of healthy children when compared with commonly used oral agents.

Effect of various sintering temperature on resistivity behaviour and magnetoresistance of La{sub 0.67}Ba{sub 0.33}MnO{sub 3}

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

Pratama, R.; Kurniawan, B., E-mail: bkuru07@gmail.com; Manaf, A.

2016-04-19

A detail work was conducted in order to investigate effect of various sintering temperature on resistivity behavior and its relation with the magneto-resistance effect of La{sub 0.67}Ba{sub 0.33}MnO{sub 3} (LBMO). The LBMO samples were synthesized using solid state reaction. Characterization using X-ray diffraction shows that all LBMO samples have a single phase for each variation. Variation of sintering temperature on the LBMO samples affects its lattice parameters. The resistivity measurement in an absence and under applied magnetic field resulted in a highly significant different values. In one of the sintering temperature variation of LBMO, an increasing resistivity had shown atmore » a low temperature and had reached its maximum value at a specific temperature, and then the resistivity decreases to the lowest value near the room temperature. Similar result observed at higher varieties of sintering temperature but with significant lower maximum resistivity.« less

Assessment of spatial distrilbution of porosity and aquifer geohydraulic parameters in parts of the Tertiary - Quaternary hydrogeoresource of south-eastern Nigeria

NASA Astrophysics Data System (ADS)

George, N. J.; Akpan, A. E.; Akpan, F. S.

2017-12-01

An integrated attempt exploring information deduced from extensive surface resistivity study in three Local Government Areas of Akwa Ibom State, Nigeria and data from hydrogeological sources obtained from water boreholes have been explored to economically estimate porosity and coefficient of permeability/hydraulic conductivity in parts of the clastic Tertiary - Quaternary sediments of the Niger Delta region. Generally, these parameters are predominantly estimated from empirical analysis of core samples and pumping test data generated from boreholes in the laboratory. However, this analysis is not only costly and time consuming, but also limited in areal coverage. The chosen technique employs surface resistivity data, core samples and pumping test data in order to estimate porosity and aquifer hydraulic parameters (transverse resistance, hydraulic conductivity and transmissivity). In correlating the two sets of results, Porosity and hydraulic conductivity were observed to be more elevated near the riverbanks. Empirical models utilising Archie's, Waxman-Smits and Kozeny-Carman Bear relations were employed characterising the formation parameters with wonderfully deduced good fits. The effect of surface conduction occasioned by clay usually disregarded or ignored in Archie's model was estimated to be 2.58 × 10-5 Siemens. This conductance can be used as a corrective factor to the conduction values obtained from Archie's equation. Interpretation aided measures such as graphs, mathematical models and maps which geared towards realistic conclusions and interrelationship between the porosity and other aquifer parameters were generated. The values of the hydraulic conductivity estimated from Waxman-Smits model was approximately 9.6 × 10-5m/s everywhere. This revelation indicates that there is no pronounced change in the quality of the saturating fluid and the geological formations that serve as aquifers even though the porosities were varying. The deciphered parameter relations can be used to estimate geohydraulic parameters in other locations with little or no borehole data.

Research Results Of Stress-Strain State Of Cutting Tool When Aviation Materials Turning

NASA Astrophysics Data System (ADS)

Serebrennikova, A. G.; Nikolaeva, E. P.; Savilov, A. V.; Timofeev, S. A.; Pyatykh, A. S.

2018-01-01

Titanium alloys and stainless steels are hard-to-machine of all the machining types. Cutting edge state of turning tool after machining titanium and high-strength aluminium alloys and corrosion-resistant high-alloy steel has been studied. Cutting forces and chip contact arears with the rake surface of cutter has been measured. The relationship of cutting forces and residual stresses are shown. Cutting forces and residual stresses vs value of cutting tool rake angle relation were obtained. Measurements of residual stresses were performed by x-ray diffraction.

Dual design resistor for high voltage conditioning and transmission lines

DOEpatents

Siggins, Timothy Lynn [Newport News, VA; Murray, Charles W [Hayes, VA; Walker, Richard L [Norfolk, VA

2007-01-23

A dual resistor for eliminating the requirement for two different value resistors. The dual resistor includes a conditioning resistor at a high resistance value and a run resistor at a low resistance value. The run resistor can travel inside the conditioning resistor. The run resistor is capable of being advanced by a drive assembly until an electrical path is completed through the run resistor thereby shorting out the conditioning resistor and allowing the lower resistance run resistor to take over as the current carrier.

The reinforcing value and liking of resistance training and aerobic exercise as predictors of adult's physical activity.

PubMed

Flack, Kyle D; Johnson, LuAnn; Roemmich, James N

2017-10-01

Reinforcing value (motivating value) is a stronger predictor than hedonic value (liking) for engaging in drug use, gambling, and eating. The associations of reinforcing value and liking with physical activity of adults have not yet been studied and may depend on the modes of exercise (e.g., aerobic/cardiovascular exercise, resistance training) under consideration. The purpose of this study was to test associations of the reinforcing value and liking of aerobic exercise training (AT) and resistance exercise training (RT) modes of exercise with usual participation in aerobic and resistance exercise in adults. Men (n=38) and women (n=50) were measured for their liking and relative reinforcing value (RRV) of AT and RT, for their usual vigorous physical activity (VPA) participation, and for usual resistance exercise behavior (Yale physical activity questionnaire). The RRV of AT (RRVAT) and liking of AT were correlated, (r=0.22, p<0.04), as were the RRV of RT (RRVRT) and liking of RT (r=0.42, p˂0.01). The reinforcing value for, but not the liking of, a mode of exercise predicted how much an individual engaged in that mode of exercise. RRVAT (p˂0.01) was positively associated with usual VPA. RRVRT (p˂0.01) was positively associated with RT behavior. The hedonic value of AT and of RT were not associated (p>0.30) with VPA or RT behavior. Reinforcing value of a mode of exercise is a stronger predictor than the liking of that mode of exercise for usual amount of participation in the exercise. Published by Elsevier Inc.

Collateral Ventilation to Congenital Hyperlucent Lung Lesions Assessed on Xenon-Enhanced Dynamic Dual-Energy CT: an Initial Experience

PubMed Central

Yang, Dong Hyun; Kim, Namkug; Park, Seung Il; Kim, Dong Kwan; Kim, Ellen Ai-Rhan

2011-01-01

Objective We wanted to evaluate the resistance to collateral ventilation in congenital hyperlucent lung lesions and to correlate that with the anatomic findings on xenon-enhanced dynamic dual-energy CT. Materials and Methods Xenon-enhanced dynamic dual-energy CT was successfully and safely performed in eight children (median age: 5.5 years, 4 boys and 4 girls) with congenital hyperlucent lung lesions. Functional assessment of the lung lesions on the xenon map was done, including performing a time-xenon value curve analysis and assessing the amplitude of xenon enhancement (A) value, the rate of xenon enhancement (K) value and the time of arrival value. Based on the A value, the lung lesions were categorized into high or low (A value > 10 Hounsfield unit [HU]) resistance to collateral ventilation. In addition, the morphologic CT findings of the lung lesions, including cyst, mucocele and an accessory or incomplete fissure, were assessed on the weighted-average CT images. The xenon-enhanced CT radiation dose was estimated. Results Five of the eight lung lesions were categorized into the high resistance group and three lesions were categorized into the low resistance group. The A and K values in the normal lung were higher than those in the low resistance group. The time of arrival values were delayed in the low resistance group. Cysts were identified in five lesions, mucocele in four, accessory fissure in three and incomplete fissure in two. Either cyst or an accessory fissure was seen in four of the five lesions showing high resistance to collateral ventilation. The xenon-enhanced CT radiation dose was 2.3 ± 0.6 mSv. Conclusion Xenon-enhanced dynamic dual-energy CT can help visualize and quantitate various degrees of collateral ventilation to congenital hyperlucent lung lesions in addition to assessing the anatomic details of the lung. PMID:21228937

Collateral ventilation to congenital hyperlucent lung lesions assessed on xenon-enhanced dynamic dual-energy CT: an initial experience.

PubMed

Goo, Hyun Woo; Yang, Dong Hyun; Kim, Namkug; Park, Seung Il; Kim, Dong Kwan; Kim, Ellen Ai-Rhan

2011-01-01

We wanted to evaluate the resistance to collateral ventilation in congenital hyperlucent lung lesions and to correlate that with the anatomic findings on xenon-enhanced dynamic dual-energy CT. Xenon-enhanced dynamic dual-energy CT was successfully and safely performed in eight children (median age: 5.5 years, 4 boys and 4 girls) with congenital hyperlucent lung lesions. Functional assessment of the lung lesions on the xenon map was done, including performing a time-xenon value curve analysis and assessing the amplitude of xenon enhancement (A) value, the rate of xenon enhancement (K) value and the time of arrival value. Based on the A value, the lung lesions were categorized into high or low (A value > 10 Hounsfield unit [HU]) resistance to collateral ventilation. In addition, the morphologic CT findings of the lung lesions, including cyst, mucocele and an accessory or incomplete fissure, were assessed on the weighted-average CT images. The xenon-enhanced CT radiation dose was estimated. Five of the eight lung lesions were categorized into the high resistance group and three lesions were categorized into the low resistance group. The A and K values in the normal lung were higher than those in the low resistance group. The time of arrival values were delayed in the low resistance group. Cysts were identified in five lesions, mucocele in four, accessory fissure in three and incomplete fissure in two. Either cyst or an accessory fissure was seen in four of the five lesions showing high resistance to collateral ventilation. The xenon-enhanced CT radiation dose was 2.3 ± 0.6 mSv. Xenon-enhanced dynamic dual-energy CT can help visualize and quantitate various degrees of collateral ventilation to congenital hyperlucent lung lesions in addition to assessing the anatomic details of the lung.

Effect of aerated concrete blockwork joints on the heat transfer performance uniformity

NASA Astrophysics Data System (ADS)

Pukhkal, Viktor; Murgul, Vera

2018-03-01

Analysis of data on the effect of joints of the aerated concrete blocks on the heat transfer uniformity of exterior walls was carried out. It was concluded, that the values of the heat transfer performance uniformity factor in the literature sources were obtained for the regular fragment of a wall construction by approximate addition of thermal conductivities. Heat flow patterns for the aerated concrete exterior walls amid different values of the thermal conductivity factors and design ambient air temperature of -26 °C were calculated with the use of "ELCUT" software for modelling of thermal patterns by finite element method. There were defined the values for the heat transfer performance uniformity factor, reduced total thermal resistance and heat-flux density for the exterior walls. The calculated values of the heat transfer performance uniformity factors, as a function of the coefficient of thermal conductivity of aerated concrete blocks, differ from the known data by a more rigorous thermal and physical substantiation.

Characterization of ultrafiltration of undiluted and diluted stored urine.

PubMed

Ouma, J; Septien, S; Velkushanova, K; Pocock, J; Buckley, C

2016-11-01

Urine ultrafiltration (UF) was studied in terms of flux, permeability, resistance and fouling. Two types of samples were used: stored urine representing the feedstock obtained from urine diversion dry toilets; and diluted stored urine representing the feedstock obtained from urinals. Three different filtration experiment sets were adopted in this study. For the first case, pressure was set in an ascending order, i.e. from 10 to 60 kPa during filtration of stored urine. For the second case, pressure was set in a descending order, i.e. from 60 to 10 kPa for the same feed stream. The third case involved filtration of diluted urine with pressure in ascending order, i.e. from 10 to 60 kPa. The results indicated that diluted urine had higher flux than undiluted urine with maximum values of 43 and 26 L·m -2 ·h -1 respectively. Cake formation was the dominating fouling mechanism during urine filtration with a contribution of about 90% to the total hydraulic resistance. The contribution of chemically irreversible fouling was low (-2%), unless operating from high to low pressures. Indeed, irreversible fouling appeared to be greater during the experiments starting at higher pressure. Although undiluted urine had a higher fouling potential compared to diluted urine, the specific cake resistance was higher for diluted urine, probably due to a denser cake caused by lower particle sizes in that sample. The permeate obtained after urine filtration had much lower suspended solids content compared to the feedstock, with rejections up to 99%. The concentration of the ionic species remained unchanged, and 75% of the organic compounds and dissolved solids remained in the permeate. Urine UF could then be used as pre-treatment to remove suspended solids.

Flexible, transparent electrodes using carbon nanotubes

PubMed Central

2012-01-01

We prepare thin single-walled carbon nanotube networks on a transparent and flexible substrate with different densities, using a very simple spray method. We measure the electric impedance at different frequencies Z(f) in the frequency range of 40 Hz to 20 GHz using two different methods: a two-probe method in the range up to 110 MHz and a coaxial (Corbino) method in the range of 10 MHz to 20 GHz. We measure the optical absorption and electrical conductivity in order to optimize the conditions for obtaining optimum performance films with both high electrical conductivity and transparency. We observe a square resistance of 1 to 8.5 kΩ for samples showing 65% to 85% optical transmittance, respectively. For some applications, we need flexibility and not transparency: for this purpose, we deposit a thick film of single-walled carbon nanotubes on a flexible silicone substrate by spray method from an aqueous suspension of carbon nanotubes in a surfactant (sodium dodecyl sulphate), thereby obtaining a flexible conducting electrode showing an electrical resistance as low as 200 Ω/sq. When stretching up to 10% and 20%, the electrical resistance increases slightly, recovering the initial value for small elongations up to 10%. We analyze the stretched and unstretched samples by Raman spectroscopy and observe that the breathing mode on the Raman spectra is highly sensitive to stretching. The high-energy Raman modes do not change, which indicates that no defects are introduced when stretching. Using this method, flexible conducting films that may be transparent are obtained just by employing a very simple spray method and can be deposited on any type or shape of surface. PMID:23074999

Lactate dehydrogenase predicts combined progression-free survival after sequential therapy with abiraterone and enzalutamide for patients with castration-resistant prostate cancer.

PubMed

Mori, Keiichiro; Kimura, Takahiro; Onuma, Hajime; Kimura, Shoji; Yamamoto, Toshihiro; Sasaki, Hiroshi; Miki, Jun; Miki, Kenta; Egawa, Shin

2017-07-01

An array of clinical issues remains to be resolved for castration-resistant prostate cancer (CRPC), including the sequence of drug use and drug cross-resistance. At present, no clear guidelines are available for the optimal sequence of use of novel agents like androgen-receptor axis-targeted (ARAT) agents, particularly enzalutamide, and abiraterone. This study retrospectively analyzed a total of 69 patients with CRPC treated with sequential therapy using enzalutamide followed by abiraterone or vice versa. The primary outcome measure was the comparative combined progression-free survival (PFS) comprising symptomatic and/or radiographic PFS. Patients were also compared for total prostate-specific antigen (PSA)-PFS, overall survival (OS), and PSA response. The predictors of combined PFS and OS were analyzed with a backward-stepwise multivariate Cox model. Of the 69 patients, 46 received enzalutamide first, followed by abiraterone (E-A group), and 23 received abiraterone, followed by enzalutamide (A-E group). The two groups were not significantly different with regard to basic data, except for hemoglobin values. In a comparison with the E-A group, the A-E group was shown to be associated with better combined PFS in Kaplan-Meier analysis (P = 0.043). Similar results were obtained for total PSA-PFS (P = 0.049), while OS did not differ between groups (P = 0.62). Multivariate analysis demonstrated that pretreatment lactate dehydrogenase (LDH) values and age were significant predictors of longer combined PFS (P < 0.05). Likewise, multivariate analysis demonstrated that pretreatment hemoglobin values and performance status were significant predictors of longer OS (P < 0.05). The results of this study suggested the A-E sequence had longer combined PSA and total PSA-PFS compared to the E-A sequence in patients with CRPC. LDH values in sequential therapy may serve as a predictor of longer combined PFS. © 2017 Wiley Periodicals, Inc.

Overall and peripheral lung function assessment by spirometry and forced oscillation technique in relation to asthma diagnosis and control.

PubMed

Heijkenskjöld Rentzhog, C; Janson, C; Berglund, L; Borres, M P; Nordvall, L; Alving, K; Malinovschi, A

2017-12-01

Classic spirometry is effort dependent and of limited value in assessing small airways. Peripheral airway involvement, and relation to poor control, in asthma, has been highlighted recently. Forced oscillation technique (FOT) offers an effort-independent assessment of overall and peripheral lung mechanics. We studied the association between lung function variables, obtained either by spirometry or multifrequency (5, 11 and 19 Hz) FOT, and asthma diagnosis and control. Spirometry measures, resistance at 5 (R5) and 19 Hz (R19), reactance at 5 Hz (X5), resonant frequency (f res ), resistance difference between 5-19 Hz (R5-R19) and Asthma Control Test scores were determined in 234 asthmatic and 60 healthy subjects (aged 13-39 years). We used standardized lung function variables in logistic regression analyses, unadjusted and adjusted for age, height, gender and weight. Lower FEV 1 /FVC (OR [95% CI] 0.47 [0.32, 0.69]) and FEF 50 (0.62 [0.46, 0.85]) per standard deviation increase, and higher R5 (3.31 [1.95, 5.62]) and R19 (2.54 [1.65, 3.91]) were associated with asthma diagnosis. Independent predictive effects of FEV 1 /FVC and R5 or R19, respectively, were found for asthma diagnosis. Lower FEV 1 /FVC and altered peripheral FOT measures (X5, f res and R5-R19) were associated with uncontrolled asthma (P-values < .05). Resistance FOT measures were equally informative as spirometry, related to asthma diagnosis, and, furthermore, offered additive information to FEV 1 /FVC, supporting a complementary role for FOT. Asthma control was related to FOT measures of peripheral airways, suggesting a potential use in identifying such involvement. Further studies are needed to determine a clinical value and relevant reference values in children, for the multifrequency FOT measurements. © 2017 John Wiley & Sons Ltd.

Activity of Ceftazidime-Avibactam against Fluoroquinolone-Resistant Enterobacteriaceae and Pseudomonas aeruginosa

PubMed Central

Pitart, C.; Marco, F.; Keating, T. A.; Nichols, W. W.

2015-01-01

Ceftazidime-avibactam and comparator antibiotics were tested by the broth microdilution method against 200 Enterobacteriaceae and 25 Pseudomonas aeruginosa strains resistant to fluoroquinolones (including strains with the extended-spectrum β-lactamase [ESBL] phenotype and ceftazidime-resistant strains) collected from our institution. The MICs and mechanisms of resistance to fluoroquinolone were also studied. Ninety-nine percent of fluoroquinolone-resistant Enterobacteriaceae strains were inhibited at a ceftazidime-avibactam MIC of ≤4 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference). Ceftazidime-avibactam was very active against ESBL Escherichia coli (MIC90 of 0.25 mg/liter), ESBL Klebsiella pneumoniae (MIC90 of 0.5 mg/liter), ceftazidime-resistant AmpC-producing species (MIC90 of 1 mg/liter), non-ESBL E. coli (MIC90 of ≤0.125 mg/liter), non-ESBL K. pneumoniae (MIC90 of 0.25 mg/liter), and ceftazidime-nonresistant AmpC-producing species (MIC90 of ≤0.5 mg/liter). Ninety-six percent of fluoroquinolone-resistant P. aeruginosa strains were inhibited at a ceftazidime-avibactam MIC of ≤8 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference), with a MIC90 of 8 mg/liter. Additionally, fluoroquinolone-resistant mutants from each species tested were obtained in vitro from two strains, one susceptible to ceftazidime and the other a β-lactamase producer with a high MIC against ceftazidime but susceptible to ceftazidime-avibactam. Thereby, the impact of fluoroquinolone resistance on the activity of ceftazidime-avibactam could be assessed. The MIC90 values of ceftazidime-avibactam for the fluoroquinolone-resistant mutant strains of Enterobacteriaceae and P. aeruginosa were ≤4 mg/liter and ≤8 mg/liter, respectively. We conclude that the presence of fluoroquinolone resistance does not affect Enterobacteriaceae and P. aeruginosa susceptibility to ceftazidime-avibactam; that is, there is no cross-resistance. PMID:25753646

Ultra-low contact resistance in graphene devices at the Dirac point

NASA Astrophysics Data System (ADS)

Anzi, Luca; Mansouri, Aida; Pedrinazzi, Paolo; Guerriero, Erica; Fiocco, Marco; Pesquera, Amaia; Centeno, Alba; Zurutuza, Amaia; Behnam, Ashkan; Carrion, Enrique A.; Pop, Eric; Sordan, Roman

2018-04-01

Contact resistance is one of the main factors limiting performance of short-channel graphene field-effect transistors (GFETs), preventing their use in low-voltage applications. Here we investigated the contact resistance between graphene grown by chemical vapor deposition (CVD) and different metals, and found that etching holes in graphene below the contacts consistently reduced the contact resistance, down to 23 Ω \\cdot μ m with Au contacts. This low contact resistance was obtained at the Dirac point of graphene, in contrast to previous studies where the lowest contact resistance was obtained at the highest carrier density in graphene (here 200 Ω \\cdot μ m was obtained under such conditions). The ‘holey’ Au contacts were implemented in GFETs which exhibited an average transconductance of 940 S m-1 at a drain bias of only 0.8 V and gate length of 500 nm, which out-perform GFETs with conventional Au contacts.

Determining resistivity of a formation adjacent to a borehole having casing using multiple electrodes and with resistances being defined between the electrodes

DOEpatents

Vail, III, William B.

1996-01-01

Methods of operation of different types of multiple electrode apparatus vertically disposed in a cased well to measure information related to the resistivity of adjacent geological formations from inside the cased well. The multiple electrode apparatus have a minimum of three spaced apart voltage measurement electrodes that electrically engage the interior of the cased well. Measurement information is obtained related to current which is caused to flow from the cased well into the adjacent geological formation. First compensation information is obtained related to a first casing resistance between a first pair of the spaced apart voltage measurement electrodes. Second compensation information is obtained related to a second casing resistance between a second pair of the spaced apart voltage measurement electrodes. The measurement information, and first and second compensation information are used to determine a magnitude related to the adjacent formation resistivity.

Determining resistivity of a formation adjacent to a borehole having casing using multiple electrodes and with resistances being defined between the electrodes

DOEpatents

Vail, W.B. III

1996-10-29

Methods of operation are disclosed for different types of multiple electrode apparatus vertically disposed in a cased well to measure information related to the resistivity of adjacent geological formations from inside the cased well. The multiple electrode apparatus have a minimum of three spaced-apart voltage measurement electrodes that electrically engage the interior of the cased well. Measurement information is obtained related to current which is caused to flow from the cased well into the adjacent geological formation. First compensation information is obtained related to a first casing resistance between a first pair of the spaced-apart voltage measurement electrodes. Second compensation information is obtained related to a second casing resistance between a second pair of the spaced-apart voltage measurement electrodes. The measurement information, and first and second compensation information are used to determine a magnitude related to the adjacent formation resistivity. 13 figs.

Formation resistivity measurements from within a cased well used to quantitatively determine the amount of oil and gas present

DOEpatents

Vail, III, William B.

1997-01-01

Methods to quantitatively determine the separate amounts of oil and gas in a geological formation adjacent to a cased well using measurements of formation resistivity are disclosed. The steps include obtaining resistivity measurements from within a cased well of a given formation, obtaining the porosity, obtaining the resistivity of formation water present, computing the combined amounts of oil and gas present using Archie's Equations, determining the relative amounts of oil and gas present from measurements within a cased well, and then quantitatively determining the separate amounts of oil and gas present in the formation.

Formation resistivity measurements from within a cased well used to quantitatively determine the amount of oil and gas present

DOEpatents

Vail, W.B. III

1997-05-27

Methods to quantitatively determine the separate amounts of oil and gas in a geological formation adjacent to a cased well using measurements of formation resistivity are disclosed. The steps include obtaining resistivity measurements from within a cased well of a given formation, obtaining the porosity, obtaining the resistivity of formation water present, computing the combined amounts of oil and gas present using Archie`s Equations, determining the relative amounts of oil and gas present from measurements within a cased well, and then quantitatively determining the separate amounts of oil and gas present in the formation. 7 figs.

Tribological behaviour and statistical experimental design of sintered iron-copper based composites

NASA Astrophysics Data System (ADS)

Popescu, Ileana Nicoleta; Ghiţă, Constantin; Bratu, Vasile; Palacios Navarro, Guillermo

2013-11-01

The sintered iron-copper based composites for automotive brake pads have a complex composite composition and should have good physical, mechanical and tribological characteristics. In this paper, we obtained frictional composites by Powder Metallurgy (P/M) technique and we have characterized them by microstructural and tribological point of view. The morphology of raw powders was determined by SEM and the surfaces of obtained sintered friction materials were analyzed by ESEM, EDS elemental and compo-images analyses. One lot of samples were tested on a "pin-on-disc" type wear machine under dry sliding conditions, at applied load between 3.5 and 11.5 × 10-1 MPa and 12.5 and 16.9 m/s relative speed in braking point at constant temperature. The other lot of samples were tested on an inertial test stand according to a methodology simulating the real conditions of dry friction, at a contact pressure of 2.5-3 MPa, at 300-1200 rpm. The most important characteristics required for sintered friction materials are high and stable friction coefficient during breaking and also, for high durability in service, must have: low wear, high corrosion resistance, high thermal conductivity, mechanical resistance and thermal stability at elevated temperature. Because of the tribological characteristics importance (wear rate and friction coefficient) of sintered iron-copper based composites, we predicted the tribological behaviour through statistical analysis. For the first lot of samples, the response variables Yi (represented by the wear rate and friction coefficient) have been correlated with x1 and x2 (the code value of applied load and relative speed in braking points, respectively) using a linear factorial design approach. We obtained brake friction materials with improved wear resistance characteristics and high and stable friction coefficients. It has been shown, through experimental data and obtained linear regression equations, that the sintered composites wear rate increases with increasing applied load and relative speed, but in the same conditions, the frictional coefficients slowly decrease.

Use of resistant ACCase mutants to screen for novel inhibitors against resistant and susceptible forms of ACCase from grass weeds.

PubMed

Shukla, Amit; Nycholat, Corwin; Subramanian, Mani V; Anderson, Richard J; Devine, Malcolm D

2004-08-11

The aryloxyphenoxypropionic acid (AOPP) and cyclohexanedione (CHD) herbicides inhibit the first committed enzyme in fatty acid biosynthesis, acetyl CoA carboxylase (ACCase). The frequent use of AOPP and CHD herbicides has resulted in the development of resistance to these herbicides in many grass weed species. New herbicides that inhibit both the susceptible and resistant forms of ACCase in grass weeds would have obvious commercial appeal. In the present study, an attempt was made to identify molecules that target both the herbicide-sensitive and -resistant forms of ACCase. Seven experimental compounds, either CHD-like or AOPP-CHD hybrids, were synthesized and assayed against previously characterized susceptible and resistant forms of ACCase. All seven compounds inhibited ACCase from sensitive biotypes of Setaria viridis and Eleusine indica (I50 values from 6.4 to >100 microM) but were not particularly potent compared to some commercialized herbicides (I50 values of 0.08-5.6 microM). In almost all cases, the I50 values for each compound assayed against the resistant ACCases were higher than those against the corresponding sensitive ACCase, indicating reduced binding to the resistant ACCases. One compound, a CHD analogue, was almost equally effective against the resistant and susceptible ACCases, although it was not a very potent ACCase inhibitor per se (I50 of 51 and 76 microM against susceptible ACCase from S. viridis and E. indica, respectively). The AOPP-CHD hybrid molecules also inhibited some of the resistant ACCases, with I50 values ranging from 6.4 to 50 microM. These compounds may be good leads for developing ACCase inhibitors that target a wider range of ACCase isoforms, including those found in AOPP- and CHD-resistant weed biotypes.

Insulin resistance and associated factors: a cross-sectional study of bank employees.

PubMed

Salaroli, Luciane Bresciani; Cattafesta, Monica; Molina, Maria Del Carmen Bisi; Zandonade, Eliana; Bissoli, Nazaré Souza

2017-04-01

Insulin resistance is characterized by the failure of target cells to respond to normal levels of circulating insulin, and this condition is related to cardiovascular disease. This study sought to evaluate the prevalence of insulin resistance and its association with markers of metabolic abnormalities and metabolic syndrome in bank employees. A cross-sectional study was performed on 498 working men and women aged ≥20 years old. The Homeostasis Model Assessment (HOMA-IR) was used to determine the presence of insulin resistance based on cut-off values of ≤2.71 for normal insulin levels and >2.71 for insulin resistance, as established for the adult Brazilian population. It was observed that the 52 (10.4%) overweight individuals with insulin resistance were 4.97 times (95%CI 1.31-18.83) more likely to have high HOMA-IR values than the normal-weight participants; among those who were obese, the likelihood increased to 17.87 (95%CI 4.36-73.21). Individuals with large waist circumferences were 3.27 times (95%CI 1.03-10.38) more likely to develop insulin resistance than those who were within normal parameters. The HOMA-IR values differed between subjects with and without metabolic syndrome, with values of 2.83±2.5 and 1.10±0.81 (p=0.001), respectively. The levels of insulin, ultrasensitive C-reactive protein and uric acid were also associated with insulin resistance. The prevalence of insulin resistance among bank employees is high, and insulin resistance is associated with and serves as a marker of metabolic syndrome. Cardiovascular disease and metabolic syndrome-associated metabolic abnormalities were observed, and insulin resistance may be a risk factor in this group of professionals.

Insulin resistance and associated factors: a cross-sectional study of bank employees

PubMed Central

Salaroli, Luciane Bresciani; Cattafesta, Monica; Molina, Maria del Carmen Bisi; Zandonade, Eliana; Bissoli, Nazaré Souza

2017-01-01

OBJECTIVE: Insulin resistance is characterized by the failure of target cells to respond to normal levels of circulating insulin, and this condition is related to cardiovascular disease. This study sought to evaluate the prevalence of insulin resistance and its association with markers of metabolic abnormalities and metabolic syndrome in bank employees. METHODS: A cross-sectional study was performed on 498 working men and women aged ≥20 years old. The Homeostasis Model Assessment (HOMA-IR) was used to determine the presence of insulin resistance based on cut-off values of ≤2.71 for normal insulin levels and >2.71 for insulin resistance, as established for the adult Brazilian population. RESULTS: It was observed that the 52 (10.4%) overweight individuals with insulin resistance were 4.97 times (95%CI 1.31-18.83) more likely to have high HOMA-IR values than the normal-weight participants; among those who were obese, the likelihood increased to 17.87 (95%CI 4.36-73.21). Individuals with large waist circumferences were 3.27 times (95%CI 1.03-10.38) more likely to develop insulin resistance than those who were within normal parameters. The HOMA-IR values differed between subjects with and without metabolic syndrome, with values of 2.83±2.5 and 1.10±0.81 (p=0.001), respectively. The levels of insulin, ultrasensitive C-reactive protein and uric acid were also associated with insulin resistance. CONCLUSION: The prevalence of insulin resistance among bank employees is high, and insulin resistance is associated with and serves as a marker of metabolic syndrome. Cardiovascular disease and metabolic syndrome-associated metabolic abnormalities were observed, and insulin resistance may be a risk factor in this group of professionals. PMID:28492722

Study on Composition, Microstructure and Wear Behavior of Fe-B-C Wear-Resistant Surfacing Alloys

NASA Astrophysics Data System (ADS)

Zhuang, Minghui; Li, Muqin; Wang, Jun; Ma, Zhen; Yuan, Shidan

2017-12-01

Fe-B-C alloy layers with various microstructures were welded on Q235 steel plates using welding powders/H08Mn2Si and welding wires composite surfacing technology. The relationship existing between the chemical composition, microstructure and wear resistance of the surfacing alloy layers was investigated by scanning electron microscopy, x-ray diffraction, electron backscatter diffraction and wear tests. The results demonstrated that the volume fractions and morphologies of the microstructures in the surfacing alloy layers could be controlled by adjusting the boron and carbon contents in the welding powders, which could further regulate the wear resistance of the surfacing alloy layers. The typical microstructures of the Fe-B-C surfacing alloy layers included dendritic Fe, rod-like Fe2B, fishbone-like Fe2B and daisy-like Fe3(C, B). The wear resistance of the alloy layers with various morphologies differed. The wear resistance order of the different microstructures was: rod-like Fe2B > fishbone-like Fe2B > daisy-like Fe3(C, B) > dendritic Fe. A large number of rod-like Fe2B with high microhardness could be obtained at the boron content of 5.70 5.90 wt.% and the carbon content of 0.50 0.60wt.%. The highest wear resistance of the Fe-B-C alloy layers reached the value of 24.1 g-1, which demonstrates the main microscopic cutting wear mechanism of the Fe-B-C alloy layers.

Functioning efficiency of intermediate coolers of multistage steam-jet ejectors of steam turbines

NASA Astrophysics Data System (ADS)

Aronson, K. E.; Ryabchikov, A. Yu.; Brodov, Yu. M.; Zhelonkin, N. V.; Murmanskii, I. B.

2017-03-01

Designs of various types of intermediate coolers of multistage ejectors are analyzed and thermal effectiveness and gas-dynamic resistance of coolers are estimated. Data on quantity of steam condensed from steam-air mixture in stage I of an ejector cooler was obtained on the basis of experimental results. It is established that the amount of steam condensed in the cooler constitutes 0.6-0.7 and is almost independent of operating steam pressure (and, consequently, of steam flow) and air amount in steam-air mixture. It is suggested to estimate the amount of condensed steam in a cooler of stage I based on comparison of computed and experimental characteristics of stage II. Computation taking this hypothesis for main types of mass produced multistage ejectors into account shows that 0.60-0.85 of steam amount should be condensed in stage I of the cooler. For ejectors with "pipe-in-pipe" type coolers (EPO-3-200) and helical coolers (EO-30), amount of condensed steam may reach 0.93-0.98. Estimation of gas-dynamic resistance of coolers shows that resistance from steam side in coolers with built-in and remote pipe bundle constitutes 100-300 Pa. Gas-dynamic resistance of "pipein- pipe" and helical type coolers is significantly higher (3-6 times) compared with pipe bundle. However, performance by "dry" (atmospheric) air is higher for ejectors with relatively high gas-dynamic resistance of coolers than those with low resistance at approximately equal operating flow values of ejectors.

Measurement of microchannel fluidic resistance with a standard voltage meter.

PubMed

Godwin, Leah A; Deal, Kennon S; Hoepfner, Lauren D; Jackson, Louis A; Easley, Christopher J

2013-01-03

A simplified method for measuring the fluidic resistance (R(fluidic)) of microfluidic channels is presented, in which the electrical resistance (R(elec)) of a channel filled with a conductivity standard solution can be measured and directly correlated to R(fluidic) using a simple equation. Although a slight correction factor could be applied in this system to improve accuracy, results showed that a standard voltage meter could be used without calibration to determine R(fluidic) to within 12% error. Results accurate to within 2% were obtained when a geometric correction factor was applied using these particular channels. When compared to standard flow rate measurements, such as meniscus tracking in outlet tubing, this approach provided a more straightforward alternative and resulted in lower measurement error. The method was validated using 9 different fluidic resistance values (from ∼40 to 600kPa smm(-3)) and over 30 separately fabricated microfluidic devices. Furthermore, since the method is analogous to resistance measurements with a voltage meter in electrical circuits, dynamic R(fluidic) measurements were possible in more complex microfluidic designs. Microchannel R(elec) was shown to dynamically mimic pressure waveforms applied to a membrane in a variable microfluidic resistor. The variable resistor was then used to dynamically control aqueous-in-oil droplet sizes and spacing, providing a unique and convenient control system for droplet-generating devices. This conductivity-based method for fluidic resistance measurement is thus a useful tool for static or real-time characterization of microfluidic systems. Copyright © 2012 Elsevier B.V. All rights reserved.

Measurement of Microchannel Fluidic Resistance with a Standard Voltage Meter

PubMed Central

Godwin, Leah A.; Deal, Kennon S.; Hoepfner, Lauren D.; Jackson, Louis A.; Easley, Christopher J.

2012-01-01

A simplified method for measuring the fluidic resistance (Rfluidic) of microfluidic channels is presented, in which the electrical resistance (Relec) of a channel filled with a conductivity standard solution can be measured and directly correlated to Rfluidic using a simple equation. Although a slight correction factor could be applied in this system to improve accuracy, results showed that a standard voltage meter could be used without calibration to determine Rfluidic to within 12% error. Results accurate to within 2% were obtained when a geometric correction factor was applied using these particular channels. When compared to standard flow rate measurements, such as meniscus tracking in outlet tubing, this approach provided a more straightforward alternative and resulted in lower measurement error. The method was validated using 9 different fluidic resistance values (from ~40 – 600 kPa s mm−3) and over 30 separately fabricated microfluidic devices. Furthermore, since the method is analogous to resistance measurements with a voltage meter in electrical circuits, dynamic Rfluidic measurements were possible in more complex microfluidic designs. Microchannel Relec was shown to dynamically mimic pressure waveforms applied to a membrane in a variable microfluidic resistor. The variable resistor was then used to dynamically control aqueous-in-oil droplet sizes and spacing, providing a unique and convenient control system for droplet-generating devices. This conductivity-based method for fluidic resistance measurement is thus a useful tool for static or real-time characterization of microfluidic systems. PMID:23245901

Pressure effect on the superconducting and the normal state of β -B i2Pd

NASA Astrophysics Data System (ADS)

Pristáš, G.; Orendáč, Mat.; Gabáni, S.; Kačmarčík, J.; Gažo, E.; Pribulová, Z.; Correa-Orellana, A.; Herrera, E.; Suderow, H.; Samuely, P.

2018-04-01

The pressure effect up to 24.0 kbar on superconducting and normal-state properties of β -B i2Pd single crystal (Tc≈4.98 K at ambient pressure) has been investigated by measurements of the electrical resistivity. In addition, we have performed the heat capacity measurements in the temperature range 0.7-300 K at ambient pressure. The recent calculations of electronic density of states, electron-phonon interaction spectral function, and phonon density of states of β -B i2Pd [Zheng and Margine, Phys. Rev. B 95, 014512 (2017), 10.1103/PhysRevB.95.014512], are used to fit the resistivity and the heat capacity data. In the superconducting state we have focused on the influence of pressure on the superconducting transition temperature Tc and upper critical field Hc 2 and a negative effect with d Tc/d p =-0.025 K /kbar and d Hc 2/d p =-8 mT /kbar is found. A simplified Bloch-Grüneisen model was used to analyze the pressure effect on the temperature dependence of the normal-state resistivity. The obtained results point to a decrease of the electron-phonon coupling parameter λ and to a shift of phonon frequencies to higher values with pressure. Moreover, the temperature dependence of the normal-state resistivity follows a T2 dependence above Tc up to about 25 K. Together with the enhanced value of Sommerfeld coefficient γ =13.23 mJ mo l-1K-2 these results point to a certain role of the electron-electron interaction in the superconducting pairing mechanism in β -B i2Pd .

Electrical properties of toad sartorius muscle fibres in summer and winter.

PubMed

Dulhunty, A F; Gage, P W

1973-05-01

1. The area and circumference of surface fibres of sartorius muscles were measured from photomicrographs of frozen sections of whole muscles, and compared with the values obtained assuming a circular cross-section. The latter assumption gave an over-estimate of the mean area of 28%, but only a 2% over-estimate of the circumference. In isolated, single fibres, the assumption gave over-estimates of 25 and 6%, of area and circumference respectively.2. The passive electrical properties of fibres were different in summer and winter. The mean internal resistivity, membrane resistance and membrane capacitance were 147 Omega.cm, 7.6 kOmega.cm(2) and 4 muF/cm(2) in summer, and 194 Omega.cm, 3.9 kOmega.cm(2) and 6.7 muF/cm(2) in winter, in fibres of comparable diameters in situ. In single fibres in summer, the mean values were 120 Omega.cm, 8.6 kOmega.cm(2) and 3.6 muF/cm(2).3. In glycerol-treated fibres the mean specific membrane capacitance was 1.0 muF/cm(2) in summer and 2.0 muF/cm(2) in winter. The internal resistivity and specific membrane resistance were 167 Omega.cm and 8.9 kOmega.cm(2) in summer, and 232 Omega.cm and 3.9 kOmega.cm(2) in winter.4. Early after-depolarizations were recorded in glycerol-treated fibres which had a low membrane capacitance, did not twitch and showed little ;creep'. Electron micrographs of glycerol-treated fibres showed disruption of the transverse tubular system and sarcoplasmic reticulum.5. After exposure of muscles to 400 mM urea or acetamide for 1 hr, muscle fibres did not twitch and had a reduced membrane capacitance in Ringer solution.

Post-fatigue fracture resistance of metal core crowns: press-on metal ceramic versus a conventional veneering system

PubMed Central

Agustín-Panadero, Rubén; Campos-Estellés, Carlos; Labaig-Rueda, Carlos

2015-01-01

Background The aim of this in vitro study was to compare the mechanical failure behavior and to analyze fracture characteristics of metal ceramic crowns with two veneering systems – press-on metal (PoM) ceramic versus a conventional veneering system – subjected to static compressive loading. Material and Methods Forty-six crowns were constructed and divided into two groups according to porcelain veneer manufacture. Group A: 23 metal copings with porcelain IPS-InLine veneering (conventional metal ceramic). Group B: 23 metal copings with IPS-InLine PoM veneering porcelain. After 120,000 fatigue cycles, the crowns were axially loaded to the moment of fracture with a universal testing machine. The fractured specimens were examined under optical stereomicroscopy and scanning electron microscope. Results Fracture resistance values showed statistically significant differences (Student’s t-test) regarding the type of ceramic veneering technique (p=0.001): Group A (conventional metal ceramics) obtained a mean fracture resistance of 1933.17 N, and Group B 1325.74N (Press-on metal ceramics). The most common type of fracture was adhesive failure (with metal exposure) (p=0.000). Veneer porcelain fractured on the occlusal surface following a radial pattern. Conclusions Metal ceramic crowns made of IPS InLine or IPS InLine PoM ceramics with different laboratory techniques all achieved above-average values for clinical survival in the oral environment according to ISO 6872. Crowns made with IPS InLine by conventional technique resisted fracture an average of 45% more than IPS InLine PoM fabricated with the press-on technique. Key words:Mechanical failure, conventional feldspathic, pressable ceramic, chewing simulator, thermocycling, compressive testing, fracture types, scanning electron microscope. PMID:26155346

Inversion of quasi-3D DC resistivity imaging data using artificial neural networks

NASA Astrophysics Data System (ADS)

Neyamadpour, Ahmad; Wan Abdullah, W. A. T.; Taib, Samsudin

2010-02-01

The objective of this paper is to investigate the applicability of artificial neural networks in inverting quasi-3D DC resistivity imaging data. An electrical resistivity imaging survey was carried out along seven parallel lines using a dipole-dipole array to confirm the validation of the results of an inversion using an artificial neural network technique. The model used to produce synthetic data to train the artificial neural network was a homogeneous medium of 100Ωm resistivity with an embedded anomalous body of 1000Ωm resistivity. The network was trained using 21 datasets (comprising 12159 data points) and tested on another 11 synthetic datasets (comprising 6369 data points) and on real field data. Another 24 test datasets (comprising 13896 data points) consisting of different resistivities for the background and the anomalous bodies were used in order to test the interpolation and extrapolation of network properties. Different learning paradigms were tried in the training process of the neural network, with the resilient propagation paradigm being the most efficient. The number of nodes, hidden layers, and efficient values for learning rate and momentum coefficient have been studied. Although a significant correlation between results of the neural network and the conventional robust inversion technique was found, the ANN results show more details of the subsurface structure, and the RMS misfits for the results of the neural network are less than seen with conventional methods. The interpreted results show that the trained network was able to invert quasi-3D electrical resistivity imaging data obtained by dipole-dipole configuration both rapidly and accurately.

Indirect selection of industrial tomato genotypes that are resistant to spider mites (Tetranychus urticae).

PubMed

Baier, J E; Resende, J T V; Faria, M V; Schwarz, K; Meert, L

2015-01-16

Acyl sugars present in the tomato Solanum lycopersicum 'LA-716' accession confer good levels of resistance to arthropod pests. The objective of the present study was to select F₂ plants from the interspecific cross Solanum pennellii 'LA-716' x Solanum lycopersicum 'Redenção' to assess resistance to spider mites (Tetranychus urticae) based on the leaf acyl sugar content and repellence tests. Four genotypes were selected with high leaflet acyl sugar content (RVTA-2010 pl#31, RVTA-2010 pl#75, RVTA-2010 pl#83, and RVTA-2010 pl#94), and an additional three genotypes with low acyl sugar content were also selected (RVTA-2010 pl#33, RVTA-2010 pl#39, and RVTA-2010 pl#73). The results from the in vivo tests used to confirm the selection of plants resistant to mites indicated that the genotypes with high acyl sugars content did not differ from the resistant parent LA-716. The negative correlation between acyl sugar content and the distance run by the mite along the leaflet surface confirmed the association between high and low allelochemical content and resistance. The medium degree of dominance (MDD) was estimated (MDD = -0.83), indicating that the high acyl sugar content was due to incomplete dominance of a recessive allele. A value of 81.85% was found for the broad sense heritability estimate, which suggests that most among-plant variation in the F2 generation is genetically based. Furthermore, 0.69 genes were estimated, which presumably confirms monogenic inheritance. Thus, indirect selection was an efficient method used to obtain industrial tomato plants that are resistant to spider mites.

Drop-Weight Impact Test on U-Shape Concrete Specimens with Statistical and Regression Analyses

PubMed Central

Zhu, Xue-Chao; Zhu, Han; Li, Hao-Ran

2015-01-01

According to the principle and method of drop-weight impact test, the impact resistance of concrete was measured using self-designed U-shape specimens and a newly designed drop-weight impact test apparatus. A series of drop-weight impact tests were carried out with four different masses of drop hammers (0.875, 0.8, 0.675 and 0.5 kg). The test results show that the impact resistance results fail to follow a normal distribution. As expected, U-shaped specimens can predetermine the location of the cracks very well. It is also easy to record the cracks propagation during the test. The maximum of coefficient of variation in this study is 31.2%; it is lower than the values obtained from the American Concrete Institute (ACI) impact tests in the literature. By regression analysis, the linear relationship between the first-crack and ultimate failure impact resistance is good. It can suggested that a minimum number of specimens is required to reliably measure the properties of the material based on the observed levels of variation. PMID:28793540

Real-time imaging of cerebral infarction in rabbits using electrical impedance tomography.

PubMed

Yang, Bin; Shi, Xuetao; Dai, Meng; Xu, Canhua; You, Fushen; Fu, Feng; Liu, Ruigang; Dong, Xiuzhen

2014-02-01

To investigate the possible use of electrical impedance tomography (EIT) in monitoring focal cerebral infarction in a rabbit model. A model of focal cerebral infarction was established in eight New Zealand rabbits using a photochemical method without craniectomy. Focal cerebral infarction was confirmed by histopathological examination. Intracranial impedance variation was measured using 16 electrodes placed in a circle on the scalp. EIT images were obtained using a damped least-squares reconstruction algorithm. The average resistivity value (ARV) of the infarct region on EIT images was calculated to quantify relative resistivity changes. A symmetry index was calculated to evaluate the relative difference in resistivity between the two sides of the cerebrum. EIT images and ARV curves showed that impedance changes caused by cerebral infarction increased linearly with irradiation time. A difference in ARV was found between measurements taken before and after infarct induction. Focal cerebral infarction can be monitored by EIT in the proposed animal model. The results are sufficiently encouraging that the authors plan to extend this study to humans, after further technical improvements.

Application of geophysical techniques for 3D geohazard mapping to delineate cavities and potential sinkholes in the northern part of Kuala Lumpur, Malaysia.

PubMed

Bakhshipour, Zeinab; Huat, Bujang B K; Ibrahim, Shaharin; Asadi, Afshin; Kura, Nura Umar

2013-01-01

This work describes the application of the electrical resistivity (ER) method to delineating subsurface structures and cavities in Kuala Lumpur Limestone within the Batu Cave area of Selangor Darul Ehsan, Malaysia. In all, 17 ER profiles were measured by using a Wenner electrode configuration with 2 m spacing. The field survey was accompanied by laboratory work, which involves taking resistivity measurements of rock, soil, and water samples taken from the field to obtain the formation factor. The relationship between resistivity and the formation factor and porosity for all the samples was established. The porosity values were plotted and contoured. A 2-dimensional and 3-dimensional representation of the subsurface topography of the area was prepared through use of commercial computer software. The results show the presence of cavities and sinkholes in some parts of the study area. This work could help engineers and environmental managers by providing the information necessary to produce a sustainable management plan in order to prevent catastrophic collapses of structures and other related geohazard problems.

Electroless Nickel Deposition for Front Side Metallization of Silicon Solar Cells

PubMed Central

Hsieh, Shu Huei; Hsieh, Jhong Min; Chen, Wen Jauh; Chuang, Chia Chih

2017-01-01

In this work, nickel thin films were deposited on texture silicon by electroless plated deposition. The electroless-deposited Ni layers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), and sheet resistance measurement. The results indicate that the dominant phase was Ni2Si and NiSi in samples annealed at 300–800 °C. Sheet resistance values were found to correlate well with the surface morphology obtained by SEM and the results of XRD diffraction. The Cu/Ni contact system was used to fabricate solar cells by using two different activating baths. The open circuit voltage (Voc) of the Cu/Ni samples, before and after annealing, was measured under air mass (AM) 1.5 conditions to determine solar cell properties. The results show that open circuit voltage of a solar cell can be enhanced when the activation solution incorporated hydrofluoric acid (HF). This is mainly attributed to the native silicon oxide layer that can be decreased and/or removed by HF with the corresponding reduction of series resistance. PMID:28805724

Short communication: Characterization of methicillin-resistant Staphylococcus aureus isolated from raw milk fresh cheese in Colombia.

PubMed

Herrera, Fanny C; García-López, María-Luisa; Santos, Jesús A

2016-10-01

The aim of this study was the characterization of a collection of 8 methicillin-resistant Staphylococcus aureus (MRSA) isolates, obtained from samples of fresh cheese (Doble Crema) produced from raw cow milk in small dairies in Colombia. All the isolates harbored the mecA and Panton-Valentine leukocidin (PVL) genes, presented with SCCmec type IV, and belonged to multilocus sequence type 8 and spa type 024. Seven isolates presented 3 closely related pulsed-field gel electrophoresis profiles. Three of them carried the staphylococcal enterotoxin B gene. The isolates were resistant to cefoxitin, oxacillin, penicillin, and ampicillin and susceptible to all non-β-lactams antibiotics tested, with minimum inhibitory concentration values for oxacillin of 4 to 8mg/L. The isolates belonged to the community-acquired MRSA group, suggesting a human source of contamination. The risk of human infection by MRSA via contaminated foods is considered low, but contaminated food commodities can contribute to the worldwide dissemination of clones of community-acquired MRSA. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Status of NTD Ge bolometer material and devices

NASA Technical Reports Server (NTRS)

Haller, E. E.; Haegel, N. M.; Park, I. S.

1986-01-01

The first IR Detector Technology Workshop took place at NASA Ames Research Center on July 12 and 13, 1983. The conclusions presented at that meeting are still valid. More was learned about the physics of hopping conduction at very low temperatures which will be important for bolometer design and operation at ever decreasing temperatures. Resistivity measurements were extended down to 50 mK. At such low temperatures, precise knowledge of the neutron capture cross sections sigma (sub n) of the various Ge isotopes is critical if one is to make an accurate prediction of the dopant concentrations and compensation, and therefore resistivity, that will result from a given irradiation. An empirical approach for obtaining the desired resistivity material is described and the process of conducting a set of experiments which will improve the knowledge of the effective sigma (sub n) values for a given location in a particular reactor is discussed. A wider range of NTD Ge samples is now available. Noise measurements on bolometers with ion implanted contacts show the no 1/f noise component appears down to 1 Hz and probably lower.

Strong, Tough, and Pest Resistant MoSi2-Base Hybrid Composite for Structural Applications

NASA Technical Reports Server (NTRS)

Hebsur, M. G.; Nathal, M. V.

1997-01-01

Addition of about 30 to 50 vol % of Si3N4 particulate to MoSi2 improved resistance to low temperature accelerated oxidation by forming a Si2ON2 protective scale and thereby eliminating catastrophic 'pest failure'. The Si3N4 addition also improved the high temperature creep strength by nearly five orders of magnitude, doubled the room temperature toughness and significantly lowered the CTE of the MoSi2 and eliminated matrix cracking in SCS-6 reinforced composites even after thermal cycling. The SCS-6 fiber reinforcement improved the room temperature fracture toughness by seven times and impact resistance by five times. The composite exhibited excellent strength and toughness improvement up to 1400 C. More recently, tape casting was adopted as the preferred processing of MoSi2-base composites for improved fiber spacing, ability to use small diameter fibers, and for lower cost. Good strength and toughness values were also obtained with fine diameter Hi-Nicalon tow fibers. This hybrid composite remains competitive with ceramic matrix composites as a replacement for Ni-base superalloys in aircraft engine applications.

Hanle measurements of electrodeposited Fe/GaAs spin tunnel contacts

NASA Astrophysics Data System (ADS)

Majumder, Sarmita; Hohertz, Donna; McNeil, James; SpringThorpe, Anthony; Kavanagh, Karen L.

2014-03-01

We report spin transport in electrodeposited Fe/n-GaAs tunnel diodes via three-terminal Hanle measurements. For temperatures between 20 K and 150 K, the spin resistance was up to 20 times higher than expected from theoretical calculations and 1000 times larger compared to a vacuum-deposited counterpart. This higher spin resistance was correlated with a higher contact resistance, and a higher concentration of oxygen impurities in the electrodeposited Fe film and interface, as detected via x-ray photoelectron and Auger spectroscopies, and inferred from Fe film nucleation rates. These results can be explained via a small effective tunnel-contact area of 5%, but extra spin filtering via interfacial states or magnetic oxide layers cannot be ruled out. The spin diffusion times (8.5 ± 0.4 ns to 1.8 ± 0.4 ns, for 20 K to 150 K) extracted from Lorentzian fits were in good agreement with values obtained from earlier 4-terminal Hanle measurements (7.8 ± 0.4 ns to 3.2 ± 0.4 ns, for 25 K to 77 K), both 10 times slower than reported vacuum-deposited contacts.

Geophysical data integration, stochastic simulation and significance analysis of groundwater responses using ANOVA in the Chicot Aquifer system, Louisiana, USA

USGS Publications Warehouse

Rahman, A.; Tsai, F.T.-C.; White, C.D.; Carlson, D.A.; Willson, C.S.

2008-01-01

Data integration is challenging where there are different levels of support between primary and secondary data that need to be correlated in various ways. A geostatistical method is described, which integrates the hydraulic conductivity (K) measurements and electrical resistivity data to better estimate the K distribution in the Upper Chicot Aquifer of southwestern Louisiana, USA. The K measurements were obtained from pumping tests and represent the primary (hard) data. Borehole electrical resistivity data from electrical logs were regarded as the secondary (soft) data, and were used to infer K values through Archie's law and the Kozeny-Carman equation. A pseudo cross-semivariogram was developed to cope with the resistivity data non-collocation. Uncertainties in the auto-semivariograms and pseudo cross-semivariogram were quantified. The groundwater flow model responses by the regionalized and coregionalized models of K were compared using analysis of variance (ANOVA). The results indicate that non-collocated secondary data may improve estimates of K and affect groundwater flow responses of practical interest, including specific capacity and drawdown. ?? Springer-Verlag 2007.

Resistance Status to the Insecticides Temephos, Deltamethrin, and Diflubenzuron in Brazilian Aedes aegypti Populations

PubMed Central

Viana-Medeiros, Priscila Fernandes; Araújo, Simone Costa; Martins, Ademir J.; Lima, José Bento Pereira

2016-01-01

Insecticides are still largely applied in public health to control disease vectors. In Brazil, organophosphates (OP) and pyrethroids (PY) are used against Aedes aegypti for years. Since 2009 Insect Growth Regulators (IGR) are also employed in the control of larvae. We quantified resistance to temephos (OP), deltamethrin (PY), and diflubenzuron (IGR) of A. aegypti samples from 12 municipalities distributed throughout the country, collected between 2010 and 2012. High levels of resistance to neurotoxic insecticides were detected in almost all populations: RR95 to temephos varied between 4.0 and 27.1; the lowest RR95 to deltamethrin was 13.1, and values higher than 70.0 were found. In contrast, all samples were susceptible to diflubenzuron (RR95 < 2.3). Biochemical tests performed with larvae and adults discarded the participation of acetylcholinesterase, the OP target, and confirmed involvement of the detoxifying enzymes esterases, mixed function oxidases, and glutathione-S-transferases. The results obtained were discussed taking into account the public chemical control component and the increase in the domestic use of insecticides during dengue epidemic seasons in the evaluated municipalities. PMID:27419140

Characteristics of MAO coating obtained on ZK60 Mg alloy under two and three steps voltage-increasing modes in dual electrolyte

NASA Astrophysics Data System (ADS)

Yang, Jun; Wang, Ze-Xin; Lu, Sheng; Lv, Wei-gang; Jiang, Xi-zhi; Sun, Lei

2017-03-01

The micro-arc oxidation process was conducted on ZK60 Mg alloy under two and three steps voltage-increasing modes by DC pulse electrical source. The effect of each mode on current-time responses during MAO process and the coating characteristic were analysed and discussed systematically. The microstructure, thickness and corrosion resistance of MAO coatings were evaluated by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), microscope with super-depth of field and electrochemical impedance spectroscopy (EIS). The results indicate that two and three steps voltage-increasing modes can improve weak spark discharges with insufficient breakdown strength in later period during the MAO process. Due to higher value of voltage and voltage increment, the coating with maximum thickness of about 20.20μm formed under two steps voltage-increasing mode shows the best corrosion resistance. In addition, the coating fabricated under three steps voltage-increasing mode shows a smoother coating with better corrosion resistance due to the lower amplitude of voltage-increasing.

Application of Geophysical Techniques for 3D Geohazard Mapping to Delineate Cavities and Potential Sinkholes in the Northern Part of Kuala Lumpur, Malaysia

PubMed Central

Bakhshipour, Zeinab; Huat, Bujang B. K.; Ibrahim, Shaharin; Asadi, Afshin

2013-01-01

This work describes the application of the electrical resistivity (ER) method to delineating subsurface structures and cavities in Kuala Lumpur Limestone within the Batu Cave area of Selangor Darul Ehsan, Malaysia. In all, 17 ER profiles were measured by using a Wenner electrode configuration with 2 m spacing. The field survey was accompanied by laboratory work, which involves taking resistivity measurements of rock, soil, and water samples taken from the field to obtain the formation factor. The relationship between resistivity and the formation factor and porosity for all the samples was established. The porosity values were plotted and contoured. A 2-dimensional and 3-dimensional representation of the subsurface topography of the area was prepared through use of commercial computer software. The results show the presence of cavities and sinkholes in some parts of the study area. This work could help engineers and environmental managers by providing the information necessary to produce a sustainable management plan in order to prevent catastrophic collapses of structures and other related geohazard problems. PMID:24501583

Analysis of electroluminescence images in small-area circular CdTe solar cells

NASA Astrophysics Data System (ADS)

Bokalič, Matevž; Raguse, John; Sites, James R.; Topič, Marko

2013-09-01

The electroluminescence (EL) imaging process of small area solar cells is investigated in detail to expose optical and electrical effects that influence image acquisition and corrupt the acquired image. An approach to correct the measured EL images and to extract the exact EL radiation as emitted from the photovoltaic device is presented. EL images of circular cadmium telluride (CdTe) solar cells are obtained under different conditions. The power-law relationship between forward injection current and EL emission and a negative temperature coefficient of EL radiation are observed. The distributed Simulation Program with Integrated Circuit Emphasis (SPICE®) model of the circular CdTe solar cell is used to simulate the dark J-V curve and current distribution under the conditions used during EL measurements. Simulation results are presented as circularly averaged EL intensity profiles, which clearly show that the ratio between resistive parameters determines the current distribution in thin-film solar cells. The exact resistance values for front and back contact layers and for CdTe bulk layer are determined at different temperatures, and a negative temperature coefficient for the CdTe bulk resistance is observed.