Ba 2TeO as an optoelectronic material: First-principles study

DOE PAGES

Sun, Jifeng; Shi, Hongliang; Du, Mao-Hua; ...

2015-05-21

The band structure, optical and defects properties of Ba 2TeO are systematically investigated using density functional theory with a view to understanding its potential as an optoelectronic or transparent conducting material. Ba 2TeO crystallizes with tetragonal structure (space group P4/nmm) and with a 2.93 eV optical band gap1. We find relatively modest band masses for both electrons and holes suggesting applications. Optical properties show a infrared-red absorption when doped. This could potentially be useful for combining wavelength filtering and transparent conducting functions. Furthermore, our defect calculations show that Ba 2TeO is intrinsically p-type conducting under Ba-poor condition. However, the spontaneousmore » formation of the donor defects may constrain the p-type transport properties and would need to be addressed to enable applications.« less

Preparation of Silica Aerogel from TEOS

PubMed

Tamon; Kitamura; Okazaki

1998-01-15

Silica alcogels were synthesized by the sol-gel polymerization of tetraethylorthosilicate (TEOS). In the synthesis, HCl and NH3 were used as hydrolysis and condensation catalysts. The gelation time became short and the visible light transmittance increased with increasing the amount of HCl or lengthening the hydrolysis time. The alcogels were dried under supercritical conditions with carbon dioxide, and silica aerogels were obtained. As a result of characterization by visible light transmission and N2 adsorption, the aerogels are mesoporous materials with high surface areas. The experimental results suggest that the aerogel properties are not influenced by the drying conditions such as extraction temperature, extraction time, depressurizing temperature, and depressurizing rate. On the other hand, the properties are changed under the conditions of sol-gel polymerization. In the preparation of highly transparent aerogels with high surface areas and large pore volumes, it is necessary to synthesize highly transparent alcogels. It is found that the visible light transmittance of alcogels is an index for preparing aerogels from TEOS. Copyright 1998 Academic Press. Copyright 1998Academic Press

VizieR Online Data Catalog: Spectral types of stars in Coalsack region (Vanas 1939)

NASA Astrophysics Data System (ADS)

Vanas, E.

2010-11-01

This table shows coordinates and identifications for 1930 stars in northern Cygnus ('Northern Coalsack' region) classified by Erik Vanas in an early spectral survey. In the source paper, the stars were identified by BD number (part I of the catalogue) and by approximate coordinates for fainter non-BD stars (part II of the catalogue). The spectral types were determined from scans of objective-prism plates (~260Å/mm). Accurate coordinates of the BD stars were derived mainly from the Tycho-2 catalogue. The non-BD stars had to be identified one-by-one from DSS images via SkyView, usually unambiguous, and coordinates found in VizieR. For the non-BD stars, the acronym [V39] was used. For pairs or crowded stars, 2MASS positions are sometimes used. Where the type applies to a near-equal double star, the coordinates are for the mid-point between the two stars (rounded to 1" precision), and the magnitude is for the combined light. The original Vanas photo-blue magnitudes are somewhat uncertain, probably including a color term. Instead standard V magnitudes from Tycho-2 or from the TASS MkIV survey (Cat. II/271) are supplied. The Vanas spectral types are formally on the 'Uppsala' system, which includes the strength of the CN band to distinguish dwarfs and giants among types later than G5. These are shown in modern MK notation. The scheme also includes a pseudo-luminosity class for hot stars based largely on the width of the Balmer lines. Since the He lines were not involved in the classification, the system loses resolution (or 'granularity') for types earlier than A0. There is also the danger at this dispersion of mistaking a late-B supergiant for an early-B dwarf. From consideration of his descriptions of the spectra, and also comparison with types from modern sources for the same stars, these 'Greek-lettered' types were transformed in modern notation as: * types 'A0μ' given as A0V * types 'A0σ' and 'A0σ+' given as B8 * types 'B{tau}-' given as B, and are mainly B3 to B

Thermodynamic characterization of Ni3TeO6, Ni2Te3O8 and NiTe2O5

NASA Astrophysics Data System (ADS)

Dawar, Rimpi; Babu, R.; Ananthasivan, K.; Anthonysamy, S.

2017-09-01

Measurement of vapour pressure of TeO2(g) over the biphasic mixture Ni3TeO6 (s) + NiO(s) in the temperature range 1143-1272 K was carried out using transpiration-thermogravimetric technique (TTG). Gibbs energy of formation of Ni3TeO6 was obtained from the temperature dependence of vapour pressure of TeO2 (g) generated by the incongruent vapourisation reaction, Ni3TeO6 (s) → NiO(s) + TeO2 (g) + 1/2 O2 in the temperature range 1143-1272 K. An isoperibol type drop calorimeter was used to measure the enthalpy increments of Ni3TeO6, Ni2Te3O8 and NiTe2O5. Thermodynamic functions viz., heat capacity, entropy and Gibbs energy functions of these compounds were derived from the experimentally measured enthalpy increment values. Third-law analysis was carried out to ascertain absence of temperature dependent systematic errors in the measurement of vapour pressure of TeO2 (g). A value of -1265.1 ± 1.5 kJ mol-1 was obtained for Δ Hf,298K o (Ni3TeO6) using third-law analysis.

Structural studies of Bi 2 O 3 -Nb 2 O 5 -TeO 2 glasses

DOE PAGES

Wilding, Martin C.; Delaizir, Gaelle; Benmore, Chris J.; ...

2016-07-25

Bi 2O 3-Nb 2O 5-TeO 2 glasses show unusual annealing behavior with appearance of spherulites within the matrix glass structure for the Bi 0.5Nb 0.5Te 3O 8 composition. The textures resemble those found previously among polyamorphic Al 2O 3-Y 2O 3 glasses containing metastably co-existing high- and low-density phases produced during quenching. However the spherulites produced within the Bi 2O 3-Nb 2O 5-TeO 2 glass are crystalline and can be identified as an “anti-glass” phase related to β-Bi 2Te 4O 11. Here, we used high energy synchrotron X-ray diffraction data to study structures of binary and ternary glasses quenched frommore » liquids within the Bi 2O 3-Nb 2O 5-TeO 2 system. These reveal a glassy network based on interconnected TeO 4 and TeO 3 units that is related to TeO 2 crystalline materials but with larger Te…Te separations due to the presence of TeO 3 groups and non-bridging oxygens linked to modifier (Bi 3 +, Nb 5 +) cations. Analysis of the viscosity-temperature relations indicates that the glass-forming liquids are “fragile” and there is no evidence for a LLPT occurring in the supercooled liquid. The glasses obtained by quenching likely correspond to a high-density amorphous (HDA) state. Subsequent annealing above T g shows mainly evidence for direct crystallization of the “anti-glass” tellurite phase. But, some evidence may exist for simultaneous formation of nanoscale amorphous spherulites that could correspond to the LDA polyamorph. The quenching and annealing behavior of Bi 2O 3-Nb 2O 5-TeO 2 supercooled liquids and glasses is compared with similar materials in the Al 2O 3-Y 2O 3 system.« less

Comparison of structural and optical properties of TeO2 nanostructures synthesized using various substrate conditions

NASA Astrophysics Data System (ADS)

Jung, Taek-Kyun; Ryou, Min; Lee, Ji-Woon; Hyun, Soong-Keun; Na, Han Gil; Jin, Changhyun

2017-11-01

Several TeO2 low-dimensional nanostructures were prepared by thermal evaporation using four substrate conditions: (1) a bare substrate, (2) a scratched substrate, (3) a Au-catalyst-assisted substrate, and (4) a multi-walled carbon nanotube (MWCNT)-assisted substrate. Scanning electron microscopy and transmission electron microscopy analysis reveals that the morphologies of the nanostructures synthesized using these methods gradually changed from nanoparticles to ultra-thin nanowires with single tetragonal-type TeO2. Photoluminescence (PL) spectra reveal that the PL intensities of the TeO2 nanomaterials obtained using methods (1) and (2) are slightly increased, whereas the intensities of the TeO2 nanostructures obtained using methods (3) and (4) differ significantly depending on the initial substrate conditions. The emission peak is also blue-shifted from 440 nm to 430 nm for the scratched surface condition due to an excitonic transition. The increase in the blue emission for the MWCNT-assisted condition is attributed to the degree and type of excitons and defects in the TeO2 nanostructures.

Structure and photoluminescence properties of TeO2-core/TiO2-shell nanowires

NASA Astrophysics Data System (ADS)

Park, Sunghoon; An, Soyeon; Lee, Chongmu

2013-12-01

TeO2-core/TiO2-shell nanowires were fabricated by thermal evaporation of Te powders and MOCVD of TiO2. The as-synthesized TeO2 nanowires showed a weak broad violet band centered at approximately 430 nm. The emission peak was shifted to a bluish violet region (∼455 nm) by the encapsulation of the nanowires with a TiO2 thin film. The intensity of the major emission from the core-shell nanowires showed strong dependence on the shell layer thickness. The strongest emission was obtained for the shell layer thickness of ∼15 nm and its intensity was approximately 80 times higher than that of the violet emission from the as-synthesized TeO2 nanowires. This enhancement in emission intensity is attributed to the subwavelength optical resonant cavity formation in the shell layer. The major emission intensity was enhanced further and blue-shifted by annealing, which might be attributed to the increase in the Ti interstitial and O vacancy concentrations in the TeO2 cores during annealing.

Phase transition and equation of state of paratellurite (TeO2) under high pressure

NASA Astrophysics Data System (ADS)

Liu, Xun; Mashimo, Tsutomu; Kawai, Nobuaki; Sekine, Toshimori; Zeng, Zhaoyi; Zhou, Xianming

2016-07-01

The Hugoniot data for TeO2 single crystals were obtained for pressures up to ˜85 GPa along both the <100> (a-axis) and <001> (c-axis) directions using a velocity interferometer system for any reflector and inclined-mirror method combined with a powder gun or two-stage light gas gun. The Hugoniot-elastic limit of TeO2 was determined to be 3.3-4.3 GPa along the c-axes. The shock velocity (U s) versus particle velocity (U p) relation for TeO2 shows a kink around U p = 1.0 km s-1, which suggests a phase transition completes at ˜26 ± 2 GPa. The Hugoniot relations of the low and high pressure phase are given by U s = 3.13(5) + 1.10(6)U p for U p < 1.0 km s-1 and U s = 2.73(9) + 1.49(5)U p for U p > 1.0 km s-1, respectively. First-principles geometry optimizations based on the generalized gradient approximation after Perdew, Burke and Ernzerhof method were also performed on TeO2. It suggested that a continuous structure distortion occurs up to 22 GPa, and the lattice parameters b and c abruptly increase and decrease at 22 GPa, respectively, indicating a first-order phase transition to the cotunnite structure phase. The equation of state of the cotunnite phase TeO2 is discussed based on the experimental and simulation results.

Expanding the remarkable structural diversity of uranyl tellurites: hydrothermal preparation and structures of K[UO(2)Te(2)O(5)(OH)], Tl(3)[(UO(2))(2)[Te(2)O(5)(OH)](Te(2)O(6))].2H(2)O, beta-Tl(2)[UO(2)(TeO(3))(2)], and Sr(3)[UO(2)(TeO(3))(2)](TeO(3))(2).

PubMed

Almond, Philip M; Albrecht-Schmitt, Thomas E

2002-10-21

The reactions of UO(2)(C(2)H(3)O(2))(2).2H(2)O with K(2)TeO(3).H(2)O, Na(2)TeO(3) and TlCl, or Na(2)TeO(3) and Sr(OH)(2).8H(2)O under mild hydrothermal conditions yield K[UO(2)Te(2)O(5)(OH)] (1), Tl(3)[(UO(2))(2)[Te(2)O(5)(OH)](Te(2)O(6))].2H(2)O (2) and beta-Tl(2)[UO(2)(TeO(3))(2)] (3), or Sr(3)[UO(2)(TeO(3))(2)](TeO(3))(2) (4), respectively. The structure of 1 consists of tetragonal bipyramidal U(VI) centers that are bound by terminal oxo groups and tellurite anions. These UO(6) units span between one-dimensional chains of corner-sharing, square pyramidal TeO(4) polyhedra to create two-dimensional layers. Alternating corner-shared oxygen atoms in the tellurium oxide chains are protonated to create short/long bonding patterns. The one-dimensional chains of corner-sharing TeO(4) units found in 1 are also present in 2. However, in 2 there are two distinct chains present, one where alternating corner-shared oxygen atoms are protonated, and one where the chains are unprotonated. The uranyl moieties in 2 are bound by five oxygen atoms from the tellurite chains to create seven-coordinate pentagonal bipyramidal U(VI). The structures of 3 and 4 both contain one-dimensional [UO(2)(TeO(3))(2)](2-) chains constructed from tetragonal bipyramidal U(VI) centers that are bridged by tellurite anions. The chains differ between 3 and 4 in that all of the pyramidal tellurite anions in 3 have the same orientation, whereas the tellurite anions in 4 have opposite orientations on each side of the chain. In 4, there are also additional isolated TeO(3)(2-) anions present. Crystallographic data: 1, orthorhombic, space group Cmcm, a = 7.9993(5) A, b = 8.7416(6) A, c = 11.4413(8) A, Z = 4; 2, orthorhombic, space group Pbam, a = 10.0623(8) A, b = 23.024(2) A, c = 7.9389(6) A, Z = 4; 3, monoclinic, space group P2(1)/n, a = 5.4766(4) A, b = 8.2348(6) A, c = 20.849(3) A, beta = 92.329(1) degrees, Z = 4; 4, monoclinic, space group C2/c, a = 20.546(1) A, b = 5.6571(3) A, c = 13.0979(8) A, beta

Fabrication of TEOS/PDMS/F127 hybrid coating materials for conservation of historic stone sculptures

NASA Astrophysics Data System (ADS)

Liu, Yurong; Liu, Jia

2016-08-01

The present work was aimed to develop a new kind of stone conservation materials (TEOS/PDMS/F127 hybrid coating) by a facile sol-gel method for the protection of decayed sandstones of Chongqing Dazu stone sculptures in China. The hydrophobic property, surface morphology, water vapor permeability, ultraviolet aging resistance and mechanical properties were measured to evaluate the effectiveness of TEOS/PDMS/F127 hybrid coating as a stone conservation material. The results showed that the addition of hydroxyl-terminated polydimethylsiloxane (PDMS-OH) contributed to improve the hydrophobic properties and incorporation of PEO-PPO-PEO (F127) surfactant resulted in the formation of superficial protrusions with micro- and nanoscopic structures and overall alteration of surface morphology and roughness, thus preventing the coating materials from cracking. After treatment with TEOS/PDMS/F127 hybrid coating materials, the ultraviolet aging resistance and mechanical properties of stone were also improved without the obvious effects on the breathability and color of the stone, indicating promising applications of TEOS/PDMS/F127 hybrid coating materials for conservation of historic stone sculptures.

Accurate polynomial expressions for the density and specific volume of seawater using the TEOS-10 standard

NASA Astrophysics Data System (ADS)

Roquet, F.; Madec, G.; McDougall, Trevor J.; Barker, Paul M.

2015-06-01

A new set of approximations to the standard TEOS-10 equation of state are presented. These follow a polynomial form, making it computationally efficient for use in numerical ocean models. Two versions are provided, the first being a fit of density for Boussinesq ocean models, and the second fitting specific volume which is more suitable for compressible models. Both versions are given as the sum of a vertical reference profile (6th-order polynomial) and an anomaly (52-term polynomial, cubic in pressure), with relative errors of ∼0.1% on the thermal expansion coefficients. A 75-term polynomial expression is also presented for computing specific volume, with a better accuracy than the existing TEOS-10 48-term rational approximation, especially regarding the sound speed, and it is suggested that this expression represents a valuable approximation of the TEOS-10 equation of state for hydrographic data analysis. In the last section, practical aspects about the implementation of TEOS-10 in ocean models are discussed.

Theoretical studies on a TeO2/ZnO/diamond-layered structure for zero TCD SAW devices

NASA Astrophysics Data System (ADS)

Dewan, Namrata; Sreenivas, K.; Gupta, Vinay

2008-08-01

High-frequency surface acoustic wave (SAW) devices based on diamond substrate are useful because of their very high SAW velocity. In the present work, SAW propagation characteristics, such as phase velocity, coupling coefficient and temperature coefficient of delay (TCD) of a TeO2/ZnO/diamond-layered structure, are examined using theoretical calculations. The ZnO/diamond bi-layer structure is found to exhibit a high positive TCD value. A zero TCD device structure is obtained after integration with a TeO2 over layer having a negative TCD value. Introduction of a non-piezoelectric TeO2 over layer on the bi-layer structure (ZnO/diamond) increases the coupling coefficient. A relatively low thickness of TeO2 thin film (~(1.6-3.1) × 10-3λ) is required to achieve temperature-stable SAW devices based on diamond.

Electrical mobility of silver ion in Ag2O-B2O3-P2O5-TeO2 glasses.

PubMed

Sklepić, Kristina; Vorokhta, Maryna; Mošner, Petr; Koudelka, Ladislav; Moguš-Milanković, Andrea

2014-10-16

The effect of adding TeO(2) into (100 - x)[0.5Ag(2)O - 0.1B(2)O(3) - 0.4P(2)O(5)] - xTeO(2), with 0-80 mol % TeO(2) glass, on the structural changes and electrical properties has been investigated. DSC and thermodilatomery were used to study their thermal behavior, structure was studied by Raman spectroscopy, and electrical properties have been studied by impedance spectroscopy over a wide temperature and frequency range. The introduction of TeO(2) as a third glass former to the glass network causes the structural transformation from TeO(3) (tp) to TeO(4) (tbp) which contributes to the changes in conductivity. The glasses with low TeO(2) content show only a slow decrease in dc conductivity with addition of TeO(2) due to the increase of the number of nonbridging oxygens, which increases the mobility of Ag(+) ions. The steep decrease in conductivity for glasses containing more than 40 mol % TeO(2) is a result of decrease of the Ag(2)O content and stronger cross-linkage in glass network through the formation of more Te-(eq)O(ax)-Te bonds in TeO(4) tbp units. The glasses obey ac conductivity scaling with respect to temperature, implying that the dynamic process is not temperature dependent. On the other hand, the scaling of the spectra for different glass compositions showed the deviations from the Summerfield scaling because of the local structural disorder which occurs as a result of the structural modifications in the tellurite glass network.

Growth and Characteristic of Amorphous Nano-Granular TeO2-V2O5-NiO Thin Films

NASA Astrophysics Data System (ADS)

Hosseinzadeh, Sh.; Rahmati, A.; Bidadi, H.

2016-12-01

TeO2-V2O5-NiO thin films were deposited using thermal evaporation from 40TeO2-(60-y)V2O5-yNiO (y=0-30mol%) target. Structural analysis of the films was identified by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The amorphous TeO2-V2O5-NiO films have nanosized clear grain structure and sharp grain boundaries. DC conductivity and current-voltage (I-V) characteristic of TeO2-V2O5-NiO thin films were measured in the temperature range of 300-423K. As nickel oxide (NiO) content increases, the DC conductivity decreases up to two orders in value (10-9-10-11Sṡcm-1). Temperature dependence of conductivity is described using the small polaron hopping (SPH) model as well. Poole-Frenkel effect is observed at high external electric field. The optical absorption spectra of the TeO2-V2O5-NiO thin films were recorded in the wavelength range of 380-1100nm. The absorption coefficient revealed bandgap shrinkage (3.01-2.3eV) and band tail widening, due to an increase in NiO content. Energy dispersive X-ray spectroscopy (EDX) was used to determine elemental composition. In TeO2-V2O5-NiO thin films, the NiO content is around fifth of the initial target.

pSK41-Like Plasmid Is Necessary for Inc18-Like vanA Plasmid Transfer from Enterococcus faecalis to Staphylococcus aureus In Vitro

PubMed Central

Clark, Nancye; Patel, Jean B.

2013-01-01

Vancomycin-resistant Staphylococcus aureus (VRSA) is thought to result from the in vivo conjugative transfer of a vanA plasmid from an Enterococcus sp. to S. aureus. We studied bacterial isolates from VRSA cases that occurred in the United States to identify microbiological factors which may contribute to this plasmid transfer. First, vancomycin-susceptible, methicillin-resistant S. aureus (MRSA) isolates from five VRSA cases were tested for their ability to accept foreign DNA by conjugation in mating experiments with Enterococcus faecalis JH2-2 containing pAM378, a pheromone-response conjugative plasmid. All of the MRSA isolates accepted the plasmid DNA with similar transfer efficiencies (∼10−7/donor CFU) except for one isolate, MRSA8, for which conjugation was not successful. The MRSA isolates were also tested as recipients in mating experiments between an E. faecalis isolate with an Inc18-like vanA plasmid that was isolated from a VRSA case patient. Conjugative transfer was successful for 3/5 MRSA isolates. Successful MRSA recipients carried a pSK41-like plasmid, a staphylococcal conjugative plasmid, whereas the two unsuccessful MRSA recipients did not carry pSK41. The transfer of a pSK41-like plasmid from a successful MRSA recipient to the two unsuccessful recipients resulted in conjugal transfer of the Inc18-like vanA plasmid from E. faecalis at a frequency of 10−7/recipient CFU. In addition, conjugal transfer could be achieved for pSK41-negative MRSA in the presence of a cell-free culture filtrate from S. aureus carrying a pSK41-like plasmid at a frequency of 10−8/recipient CFU. These results indicated that a pSK41-like plasmid can facilitate the transfer of an Inc18-like vanA plasmid from E. faecalis to S. aureus, possibly via an extracellular factor produced by pSK41-carrying isolates. PMID:23089754

Guided-Wave TeO2 Acousto-Optic Devices

DTIC Science & Technology

1991-01-12

In this research program, Guided-wave TeO2 Acousto - Optic Devices, the properties of surface acoustic waves on tellurium dioxide single crystal...surfaces has been studied for its potential applications as acousto - optic signal processing devices. Personal computer based numerical method has been...interaction with laser beams. Use of the acousto - optic probe, the surface acoustic wave velocity and field distribution have been obtained and compared

Structural, mechanical and optical investigations in the TeO2-rich part of the TeO2-GeO2-ZnO ternary glass system

NASA Astrophysics Data System (ADS)

Ghribi, N.; Dutreilh-Colas, M.; Duclère, J.-R.; Gouraud, F.; Chotard, T.; Karray, R.; Kabadou, A.; Thomas, P.

2015-02-01

Stable glasses are successfully synthesized in the TeO2-GeO2-ZnO system at 850 °C by the melt-quenching method and the glass forming domain is determined in the TeO2-rich part of the diagram. The thermal study, carried out using differential scanning calorimetry, reveals that the glass transition temperature, as well as the thermal stability, increases with the addition of ZnO or GeO2. Bulk glass samples are elaborated within two series of compositions, corresponding to fixed concentrations in GeO2 (respectively 5 or 10 mol. %), and to various contents in ZnO. Structural changes caused by the ZnO addition are discussed based on Raman spectroscopy data. A progressive but very moderate network depolymerization is shown with increasing amount of ZnO. However, two different regimes can be identified, depending on the ZnO content. It is believed that ZnO acts as a network modifier for compositions below 20 mol. %, and starts to participate as a glass network former over such concentration. It is well evidenced that GeO2 contributes to the increase in Young's modulus E, evaluated from ultrasonic echography measurements. In addition, this oxide favors the network reticulation detected by the decrease of the Poisson ratio and the increase of the fractal bond connectivity. However, the role of ZnO is more complicated and will be extensively discussed. The decrease in the atomic packing density Cg probably explains the global evolution of E as a function of ZnO content. The refractive indices and optical band gap energies are extracted from UV-Visible-NIR optical transmission data. For the studied glasses, it is found that the transmission threshold decreases with larger ZnO contents, reflecting the increase in the optical band gap value. Refractive index is finally seen to decrease as a function of both ZnO and GeO2 contents. Such variation is explained by the decrease of the molar electronic polarizability, and by the lower optical basicity values known for TeO3 entities

Defining the Role of the Environment in the Emergence and Persistence of vanA Vancomycin-Resistant Enterococcus (VRE) in an Intensive Care Unit: A Molecular Epidemiological Study.

PubMed

Lee, Andie S; White, Elizabeth; Monahan, Leigh G; Jensen, Slade O; Chan, Raymond; van Hal, Sebastiaan J

2018-06-01

OBJECTIVETo describe the transmission dynamics of the emergence and persistence of vanA vancomycin-resistant enterococcus (VRE) in an intensive care unit (ICU) using whole-genome sequencing of patient and environmental isolates.DESIGNRetrospective cohort study.SETTINGICU in a tertiary referral center.PARTICIPANTSPatients admitted to the ICU over an 11-month period.METHODS VanA VRE isolated from patients (n=31) were sequenced using the Illumina MiSeq platform. Environmental samples from bed spaces, equipment, and waste rooms were collected. All vanA VRE-positive environmental samples (n=14) were also sequenced. Data were collected regarding patient ward and bed movements.RESULTSThe 31 patient vanA VRE isolates were from screening (n=19), urine (n=4), bloodstream (n=3), skin/wound (n=3), and intra-abdominal (n=2) sources. The phylogeny from sequencing data confirmed several VRE clusters, with 1 group accounting for 38 of 45 isolates (84%). Within this cluster, cross-transmission was extensive and complex across the ICU. Directionality indicated that colonized patients contaminated environmental sites. Similarly, environmental sources not only led to patient colonization but also to infection. Notably, shared equipment acted as a conduit for transmission between different ICU areas. Infected patients, however, were not linked to further VRE transmission.CONCLUSIONSGenomic sequencing confirmed a predominantly clonal outbreak of VRE with complex transmission dynamics. The environmental reservoir, particularly from shared equipment, played a key role in ongoing VRE spread. This study provides evidence to support the use of multifaceted strategies, with an emphasis on measures to reduce bacterial burden in the environment, for successful VRE control.Infect Control Hosp Epidemiol 2018;39:668-675.

Diversity of Tn1546 in vanA-positive Enterococcus faecium clinical isolates with VanA, VanB, and VanD phenotypes and susceptibility to vancomycin.

PubMed

Cha, J O; Yoo, J I; Kim, H K; Kim, H S; Yoo, J S; Lee, Y S; Jung, Y H

2013-10-01

To investigate diversity in the vanA cluster in Enterococcus faecium isolates from nontertiary hospitals. We identified 43 vanA-positive Ent. faecium isolates, including two vancomycin-susceptible isolates, from hospitals between 2003 and 2006. Of these isolates, >85% were resistant to ampicillin, erythromycin and ciprofloxacin. The vanA cluster was classified into six types using overlapping PCR, but the prototype transposon Tn1546 was not found. Most vanA-positive vancomycin-resistant Enterococcus (VRE) carried IS1216V and belonged to Type III (58·1%) or Type II (20·9%). vanY, vanZ and IS1216V were observed in the left and right ends of Type III with long-range PCR. IS1216V was also observed within vanS and vanX in the two vancomycin-susceptible isolates and in two vancomycin-resistant isolates. No VRE isolates with VanB and VanD phenotypes contained point mutations in vanS, unlike in previous reports. Sequence types (STs) of all isolates belonged to clonal complex 17, and ST78 was predominant. Insertion sequences, especially IS1216V, cause structural variation in the vanA cluster. We report the first observation of vanY and vanZ at the left end of Tn1546 in clinical isolates. This is the first report of the frequency of vancomycin resistance and diversity of Tn1546 in vanA-positive Ent. faecium isolates from nontertiary hospitals. © 2013 The Society for Applied Microbiology.

Phase Equilibria Study in the TeO2-Na2O-SiO2 System in Air Between 723 K (500 °C) and 1473 K (1200 °C)

NASA Astrophysics Data System (ADS)

Santoso, Imam; Taskinen, Pekka

2016-08-01

Knowledge of phase equilibria in the TeO2-Na2O-SiO2 system at elevated temperatures is important for ceramic and glass industries and for improving the operation of the smelting process of tellurium-containing materials. A review of previous investigations has indicated, however, that there are omissions in the available datasets on the liquidus temperatures of the molten TeO2-Na2O-SiO2 mixtures. The employed experimental method included equilibration of mixtures made from high purity oxides, rapid quenching of the equilibrated samples in water and followed by compositional analysis of the phases using an electron probe X-ray microanalyzer. The liquidus and phase equilibria in the TeO2-SiO2, TeO2-Na2O, and SiO2-TeO2-Na2O systems have been studied for a wide range of compositions between 723 K (500 °C) and 1473 K (1200 °C) at TeO2, SiO2, and Na2SiO3 saturations. New data have been generated in the SiO2-TeO2-Na2O system at SiO2 saturation. The liquidus compositions in the TeO2-Na2O system at TeO2 saturation have been compared with the previous data and an assessed phase diagram.

Vancomycin-resistant enterococci with vanA gene in treated municipal wastewater and their association with human hospital strains.

PubMed

Oravcova, Veronika; Mihalcin, Matus; Zakova, Jana; Pospisilova, Lucie; Masarikova, Martina; Literak, Ivan

2017-12-31

Vancomycin-resistant enterococci (VRE) are pathogens of increasing medical importance. In Brno, Czech Republic, we collected 37 samples from the effluent of a wastewater treatment plant (WWTP), 21 surface swabs from hospital settings, and 59 fecal samples from hospitalized patients and staff. Moreover, we collected 284 gull cloacal swabs from the colony situated 35km downstream the WWTP. Samples were cultured selectively. Enterococci were identified using MALDI-TOF MS, phenotypically tested for susceptibility to antibiotics, and by PCR for occurrence of resistance and virulence genes. Pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were used to examine genotypic diversity. VRE carrying the vanA gene were found in 32 (86%, n=37) wastewater samples, from which we obtained 49 isolates: Enterococcus faecium (44) and Enterococcus gallinarum (2), Enterococcus casseliflavus (2), and Enterococcus raffinosus (1). From 33 (69%) of 48 inpatient stool samples, we obtained 39 vanA-carrying VRE, which belonged to E. faecium (33 isolates), Enterococcus faecalis (4), and Enterococcus raffinosus (2). Nearly one-third of the samples from hospital surfaces contained VRE with the vanA gene. VRE were not detected among gulls. Sixty-seven (84%, n=80) E. faecium isolates carried virulence genes hyl and/or esp. Virulence of E. faecalis was encoded by gelE, asa1, and cylA genes. A majority of the E. faecium isolates belonged to the clinically important sequence types ST17 (WWTP: 10 isolates; hospital: 4 isolates), ST18 (9;8), and ST78 (5;0). The remaining isolates belonged to ST555 (2;0), ST262 (1;6), ST273 (3;0), ST275 (1;0), ST549 (2;0), ST19 (0;1), ST323 (3;0), and ST884 (7;17). Clinically important enterococci carrying the vanA gene were almost continually detectable in the effluent of the WWTP, indicating insufficient removal of VRE during wastewater treatment and permanent shedding of these antibiotic resistant pathogens into the environment from this

Evaluation of TeO2 content on the optical and spectroscopic properties of Yb3+-doped calcium borotellurite glasses.

PubMed

Lima, A M O; Gomes, J F; Hegeto, F L; Medina, A N; Steimacher, A; Barboza, M J

2018-03-15

This paper reports the synthesis and the characterization of Yb 3+ -doped calcium borotellurite (CaBTeX) glasses with composition 10CaF 2 -(29.5-0.4x)CaO-(60-0.6x)B 2 O 3 -xTeO 2 -0.5Yb 2 O 3 (x=10, 16, 22, 31 and 54mol%). The results of XRD confirm the amorphous character of all the samples. The density, molar volume, refractive index and electronic polarizability values show an increase with TeO 2 content. Otherwise, the optical band gap energy shows a decrease with the increase of TeO 2 content. The replacement of CaO and B 2 O 3 by TeO 2 changes the glass structure, which decreases the excited Yb 3+ /cm 3 and, consequently, the luminescence intensity. The temperature dependence of luminescence was studied for all the samples up to 420K. The fluorescence lifetime does not change significantly due to TeO 2 addition. In addition, absorption and emission cross section were calculated and present high values as compared to other tellurite and phosphate glasses. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of TeO2 content on the optical and spectroscopic properties of Yb3 +-doped calcium borotellurite glasses

NASA Astrophysics Data System (ADS)

Lima, A. M. O.; Gomes, J. F.; Hegeto, F. L.; Medina, A. N.; Steimacher, A.; Barboza, M. J.

2018-03-01

This paper reports the synthesis and the characterization of Yb3 +-doped calcium borotellurite (CaBTeX) glasses with composition 10CaF2-(29.5 - 0.4x)CaO-(60 - 0.6x)B2O3-xTeO2-0.5Yb2O3 (x = 10, 16, 22, 31 and 54 mol%). The results of XRD confirm the amorphous character of all the samples. The density, molar volume, refractive index and electronic polarizability values show an increase with TeO2 content. Otherwise, the optical band gap energy shows a decrease with the increase of TeO2 content. The replacement of CaO and B2O3 by TeO2 changes the glass structure, which decreases the excited Yb3 +/cm3 and, consequently, the luminescence intensity. The temperature dependence of luminescence was studied for all the samples up to 420 K. The fluorescence lifetime does not change significantly due to TeO2 addition. In addition, absorption and emission cross section were calculated and present high values as compared to other tellurite and phosphate glasses.

Spectroscopic and thermal study of a new glass from TeO2sbnd Ga2O3sbnd GeO2 system

NASA Astrophysics Data System (ADS)

Marczewska, Agnieszka; Środa, Marcin

2018-07-01

Tellurium oxide and germanium oxide based glasses are classified as the heavy metal oxide glasses, with phonon energies below 880 cm-1. These glasses transmit to longer wavelengths when compared to borate, phosphate and silicate glasses because of the heavier mass of germanium. In this paper we present a new promising TeO2sbnd Ga2O3sbnd GeO2 glasses with high thermal stability and good optical properties in the near and mid-IR regions. The glass can be easily obtained for the wide range of Te/Ge ratio, which gives opportunity to engineering desirable properties. Based on the FT-IR spectra it could be stated that the tellurite network is monotonically transformed into germanate one as the GeO2 content increases. Admixtures of GeO2 into the network of tellurite glass causes the conversion of [TeO4] to [TeO3] units. Thus, the network of the glass could be consider as a mixture of the [TeO4], [TeO3] and [GeO4] units and with Ga3+ ions playing the role of its modifier. The glasses demonstrate high transmittance in mid-IR up to 6 μm what makes these materials suitable for mid-IR applications.

SAW propagation characteristics of TeO3/3C-SiC/LiNbO3 layered structure

NASA Astrophysics Data System (ADS)

Soni, Namrata D.

2018-04-01

Surface acoustic wave (SAW) devices based on Lithium Niobate (LiNbO3) single crystal are advantageous because of its high SAW phase velocity, electromechanical coupling coefficient and cost effectiveness. In the present work a new multi-layered TeO3/3C-SiC/128° Y-X LiNbO3 SAW device has been proposed. SAW propagation properties such as phase velocity, coupling coefficient and temperature coefficient of delay (TCD) of the TeO3/SiC/128° Y-X LiNbO3 multi layered structure is examined using theoretical calculations. It is found that the integration of 0.09λ thick 3C-SiC over layer on 128° Y-X LiNbO3 increases its electromechanical coupling coefficient from 5.3% to 9.77% and SAW velocity from 3800 ms‑1 to 4394 ms‑1. The SiC/128° Y-X LiNbO3 bilayer SAW structure exhibits a high positive TCD value. A temperature stable layered SAW device could be obtained with introduction of 0.007λ TeO3 over layer on SiC/128° Y-X LiNbO3 bilayer structure without sacrificing the efficiency of the device. The proposed TeO3/3C-SiC/128° Y-X LiNbO3 multi-layered SAW structure is found to be cost effective, efficient, temperature stable and suitable for high frequency application in harsh environment.

Large optical second-order nonlinearity of poled WO3-TeO2 glass.

PubMed

Tanaka, K; Narazaki, A; Hirao, K

2000-02-15

Second-harmonic generation, one of the second-order nonlinear optical properties of thermally and electrically poled WO>(3)-TeO>(2) glasses, has been examined. We poled glass samples with two thicknesses (0.60 and 0.86 mm) at various temperatures to explore the effects of external electric field strength and poling temperature on second-order nonlinearity. The dependence of second-harmonic intensity on the poling temperature is maximum at a specific poling temperature. A second-order nonlinear susceptibility of 2.1 pm/V was attained for the 0.60-mm-thick glass poled at 250 degrees C. This value is fairly large compared with those for poled silica and tellurite glasses reported thus far. We speculate that the large third-order nonlinear susceptibility of WO>(3)- TeO>(2) glasses gives rise to the large second-order nonlinearity by means of a X((2)) = 3X((3)) E(dc) process.

2.3 µm laser potential of TeO2 based glasses

NASA Astrophysics Data System (ADS)

Denker, B. I.; Dorofeev, V. V.; Galagan, B. I.; Motorin, S. E.; Sverchkov, S. E.

2017-09-01

Tm3+ doped TeO2-based well-dehydrated glasses were synthesized and investigated. The analysis of their spectral and relaxation properties have showed that these glasses can be a suitable host for bulk and fiber lasers emitting at ~2.3 µm wavelength (3H4-3H5 Tm3+ transition). Laser action in the bulk glass sample was demonstrated.

Ho3+-doped AlF3-TeO2-based glass fibers for 2.1 µm laser applications

NASA Astrophysics Data System (ADS)

Wang, S. B.; Jia, Z. X.; Yao, C. F.; Ohishi, Y.; Qin, G. S.; Qin, W. P.

2017-05-01

Ho3+-doped AlF3-TeO2-based glass fibers based on AlF3-BaF2-CaF2-YF3-SrF2-MgF2-TeO2 glasses are fabricated by using a rod-in-tube method. The glass rod including a core and a thick cladding layer is prepared by using a suction method, where the thick cladding layer is used to protect the core from the effect of surface crystallization during the fiber drawing. By inserting the glass rod into a glass tube, the glass fibers with relatively low loss (~2.3 dB m-1 @ 1560 nm) are prepared. By using a 38 cm long Ho3+-doped AlF3-TeO2-based glass fiber as the gain medium and a 1965 nm fiber laser as the pump source, 2065 nm lasing is obtained for a threshold pump power of ~220 mW. With further increasing the pump power to ~325 mW, the unsaturated output power of the 2065 nm laser is about 82 mW and the corresponding slope efficiency is up to 68.8%. The effects of the gain fiber length on the lasing threshold, the slope efficiency, and the operating wavelength are also investigated. Our experimental results show that Ho3+-doped AlF3-TeO2-based glass fibers are promising gain media for 2.1 µm laser applications.

Mass loss of a TEOS-coated, reinforced carbon-carbon composite subjected to a simulted shuttle entry environment

NASA Technical Reports Server (NTRS)

Stroud, C. W.; Rummler, D. R.

1980-01-01

Coated, reinforced carbon-carbon (RCC) is used for the leading edges of the space shuttle. The mass loss characteristics of RCC specimens coated with tetraethyl orthosilicate (TEOS) were determine for conditions which simulated the environment expected at the lug attachment area of the leading edge. Mission simulation included simultaneous application of load, temperature, and oxygen partial pressure. Maximum specimen temperature was 900 K (1160 F). Specimens were exposed for up to 80 simulated missions. Stress levels up to 6.8 MPa (980 psi) did not significantly affect the mass loss characteristics of the TEOS-coated RCC material. Mass loss was correlated with the bulk density of the specimens.

Conservation of Monuments by a Three-Layered Compatible Treatment of TEOS-Nano-Calcium Oxalate Consolidant and TEOS-PDMS-TiO₂ Hydrophobic/Photoactive Hybrid Nanomaterials.

PubMed

Kapridaki, Chrysi; Verganelaki, Anastasia; Dimitriadou, Pipina; Maravelaki-Kalaitzaki, Pagona

2018-04-27

In the conservation of monuments, research on innovative nanocomposites with strengthening, hydrophobic and self-cleaning properties have attracted the interest of the scientific community and promising results have been obtained as a result. In this study, stemming from the need for the compatibility of treatments in terms of nanocomposite/substrate, a three-layered compatible treatment providing strengthening, hydrophobic, and self-cleaning properties is proposed. This conservation approach was implemented treating lithotypes and mortars of different porosity and petrographic characteristics with a three-layered treatment comprising: (a) a consolidant, tetraethoxysilane (TEOS)-nano-Calcium Oxalate; (b) a hydrophobic layer of TEOS-polydimethylsiloxane (PDMS); and (c) a self-cleaning layer of TiO₂ nanoparticles from titanium tetra-isopropoxide with oxalic acid as hole-scavenger. After the three-layered treatment, the surface hydrophobicity was improved due to PDMS and nano-TiO₂ in the interface substrate/atmosphere, as proven by the homogeneity and the Si⁻O⁻Ti hetero-linkages of the blend protective/self-cleaning layers observed by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Fourier-Transform Infrared Spectroscopy (FTIR). The aesthetic, microstructural, mechanical and permeabile compatibility of the majority of treated substrates ranged within acceptability limits. The improved photocatalytic activity, as proven by the total discoloration of methylene blue in the majority of cases, was attributed to the anchorage of TiO₂, through the Si⁻O⁻Ti bonds to SiO₂, in the interface with the atmosphere, thus enhancing photoactivation.

Magnetic ground state of the layered honeycomb compound Na2Co2TeO6

NASA Astrophysics Data System (ADS)

Bera, A. K.; Yusuf, S. M.

2018-04-01

The magnetic correlations in the 2D layered honeycomb compound Na2Co2TeO6 has been investigated. The temperature dependent susceptibility curve reveals a transition to the magnetically ordered state at TN ˜ 25 K. The temperature dependent neutron diffraction study confirms an antiferromagnetic ordering below TN. The magnetic ground state is determined to be a zigzag antiferromagnet that appears due to competing exchange interactions beyond nearest neighbors. The moments align along the crystallographic b axis with reduced ordered magnetic moment values of 2.72(2) μB/Co2+ and 2.52(3) μB/Co2+ for two Co sites, respectively. In comparison to the theoretical phase diagram the determined zigzag antiferromagnetic ground state suggests that the compound Na2Co2TeO6 is situated in the proximity to the quantum spin liquid state in the phase diagram.

Attenuation process of the longitudinal phonon mode in a TeO2 crystal in the 20-GHz range

NASA Astrophysics Data System (ADS)

Ohno, S.; Sonehara, T.; Tatsu, E.; Koreeda, A.; Saikan, S.

2017-06-01

We experimentally investigated the hypersonic attenuation process of a longitudinal mode (L-mode) sound wave in TeO2 from room temperature to a lower temperature using Brillouin scattering and impulsive stimulated thermal scattering (ISTS) measurements. For precise measurement of the Brillouin linewidth at low temperatures, whereby the mean free path of the phonon becomes longer than the sample length, it is indispensable that the phonon should propagate along the phonon-resonance direction. To figure out the suitable direction, we defined two indices characterizing a degree of phonon divergence and a purity of propagation direction. The best direction that we found from these indices is [110] direction in TeO2, and it was used to discuss the temperature and frequency dependences of Brillouin spectra. We extracted the temperature dependence of the attenuation rate of T4 from the modulated Brillouin spectra due to the phonon resonance below Debye temperature. The frequency dependence ω1 of the hypersonic attenuation was also estimated from the polarization dependence of the Brillouin linewidth. Theoretically, it predicted that the L-mode phonon attenuation at low temperatures in TeO2 is a result of Herring's process, which shows the attenuation behavior of ω2T3 . The ω1T4 dependence is not allowed in Herring's process but is allowed by the L +L →L process, which has been considered to be forbidden so far. We evaluated the thermal phonon lifetime using ISTS and established that it was finite even at 20 K, thereby allowing the L +L →L process. Therefore, we conclude that the L +L →L process dominates the attenuation of an L-mode phonon in TeO2 in the low-temperature region.

Absolute Salinity, ''Density Salinity'' and the Reference-Composition Salinity Scale: present and future use in the seawater standard TEOS-10

NASA Astrophysics Data System (ADS)

Wright, D. G.; Pawlowicz, R.; McDougall, T. J.; Feistel, R.; Marion, G. M.

2011-01-01

Salinity plays a key role in the determination of the thermodynamic properties of seawater and the new TEOS-101 standard provides a consistent and effective approach to dealing with relationships between salinity and these thermodynamic properties. However, there are a number of practical issues that arise in the application of TEOS-10, both in terms of accuracy and scope, including its use in the reduction of field data and in numerical models. First, in the TEOS-10 formulation for IAPSO Standard Seawater, the Gibbs function takes the Reference Salinity as its salinity argument, denoted SR, which provides a measure of the mass fraction of dissolved material in solution based on the Reference Composition approximation for Standard Seawater. We discuss uncertainties in both the Reference Composition and the Reference-Composition Salinity Scale on which Reference Salinity is reported. The Reference Composition provides a much-needed fixed benchmark but modified reference states will inevitably be required to improve the representation of Standard Seawater for some studies. However, the Reference-Composition Salinity Scale should remain unaltered to provide a stable representation of salinity for use with the TEOS-10 Gibbs function and in climate change detection studies. Second, when composition anomalies are present in seawater, no single salinity variable can fully represent the influence of dissolved material on the thermodynamic properties of seawater. We consider three distinct representations of salinity that have been used in previous studies and discuss the connections and distinctions between them. One of these variables provides the most accurate representation of density possible as well as improvements over Reference Salinity for the determination of other thermodynamic properties. It is referred to as "Density Salinity" and is represented by the symbol SAdens; it stands out as the most appropriate representation of salinity for use in dynamical physical

Absolute Salinity, "Density Salinity" and the Reference-Composition Salinity Scale: present and future use in the seawater standard TEOS-10

NASA Astrophysics Data System (ADS)

Wright, D. G.; Pawlowicz, R.; McDougall, T. J.; Feistel, R.; Marion, G. M.

2010-08-01

Salinity plays a key role in the determination of the thermodynamic properties of seawater and the new TEOS-101 standard provides a consistent and effective approach to dealing with relationships between salinity and these thermodynamic properties. However, there are a number of practical issues that arise in the application of TEOS-10, both in terms of accuracy and scope, including its use in the reduction of field data and in numerical models. First, in the TEOS-10 formulation for IAPSO Standard Seawater, the Gibbs function takes the Reference Salinity as its salinity argument, denoted SR, which provides a measure of the mass fraction of dissolved material in solution based on the Reference Composition approximation for Standard Seawater. We discuss uncertainties in both the Reference Composition and the Reference-Composition Salinity Scale on which Reference Salinity is reported. The Reference Composition provides a much-needed fixed benchmark but modified reference states will inevitably be required to improve the representation of Standard Seawater for some studies. The Reference-Composition Salinity Scale should remain unaltered to provide a stable representation of salinity for use with the TEOS-10 Gibbs function and in climate change detection studies. Second, when composition anomalies are present in seawater, no single salinity variable can fully represent the influence of dissolved material on the thermodynamic properties of seawater. We consider three distinct representations of salinity that have been used in previous studies and discuss the connections and distinctions between them. One of these variables provides the most accurate representation of density possible as well as improvements over Reference Salinity for the determination of other thermodynamic properties. It is referred to as "Density Salinity" and is represented by the symbol SAdens; it stands out as the most appropriate representation of salinity for use in dynamical physical

Safety conditions for irradiation, transporting, and melting of sintered TeO2 during the industrial production of 131I.

PubMed

Alanís, José; Segovia, A; Navarrete, M

2004-08-01

The development of a program to produce 131I by neutron activation of previously sintered TeO2, was started at the Nuclear Center of Mexico 3 y ago. Since then, the problems related to producing high purity, sintered TeO2 for neutron activation, transport of the activated samples and melting of the samples to retrieve the 131I have been satisfactorily solved. The main problems, related to health physics, arise when the process is conducted on a daily basis. Described are the irradiation conditions for sintered TeO2, retrieval of the sample from the pool, and the transport of the radioactive source after a 4-d cooling time. The radiation dose in the room where the hot cell is located increases from 2 microSv h(-1) (0.2 mrem h(-1)) to 4 microSv h(-1) (0.4 mrem h(-1)) during the melting of the radioactive (131+131m)TeO2, and the pumping out and dissolution of gaseous 131I. These measurements are below the maximum permissible levels and the ALARA concept has been assured through each step of the process and no leaks have been found in the system.

Structural, thermal and optical properties of TeO2-ZnO-CdO-BaO glasses doped with VO(2+).

PubMed

Sreenivasulu, V; Upender, G; Chandra Mouli, V; Prasad, M

2015-09-05

The glasses with composition 64TeO2-15ZnO-(20-x)CdO-xBaO-1V2O5 (0⩽x⩽20 mol%) were prepared by conventional melt quenching technique. X-ray diffraction analysis was used to confirm the amorphous nature of the glasses. The optical absorption studies revealed that the cut-off wavelength (λα) decreases while optical band gap energy (Eopt) and Urbach energy (ΔE) values increase with an increase of BaO content. Refractive index (n) evaluated from Eopt was found to decrease with an increase of BaO content. The physical parameters such as density (ρ), molar volume (Vm), oxygen packing density (OPD), optical basicity (Λ), molar refraction (Rm), and metallization criterion (M) evaluated and discussed. FTIR and Raman spectroscopic studies showed that the glass network consists of TeO4, TeO3+1/TeO3 and ZnO4 units as basic structural units. The glass transition temperature (Tg) of glass sample, onset crystallization temperature (To) and thermal stability ΔT were determined from Differential Scanning Calorimetry (DSC). Using electron paramagnetic resonance (EPR) spectra of vanadium glasses the spin Hamiltonian parameters and dipolar hyperfine coupling parameters of VO(2+) ions were calculated. It was found that V(4+) ions in these glasses exist as VO(2+) in octahedral coordination with a tetragonal distortion and have C4V symmetry with ground state dxy. Tetragonality (Δg∥/Δg⊥) of vanadium ion sites exhibited non-linear variation with BaO content. Copyright © 2015 Elsevier B.V. All rights reserved.

Raman spectroscopy, thermal and optical properties of TeO2-ZnO-Nb2O5-Nd2O3 glasses

NASA Astrophysics Data System (ADS)

Kamalaker, V.; Upender, G.; Ramesh, Ch.; Chandra Mouli, V.

2012-04-01

The glasses with composition 75TeO2-10ZnO-(15-x)Nb2O5-xNd2O3 (0 ≤ x ≤ 9 mol%) were prepared using melt quenching method and their physical properties such as density (ρ), molar volume (VM), average crosslink density (n¯), oxygen packing density (OPD) and number of bonds per unit volume (nb) were determined. Raman spectroscopic studies showed that the glass network consists of TeO4, TeO3+1, TeO3 and NbO6 units as basic structural units. The glass transition temperature (Tg), crystallization onset (To) and thermal stability (ΔT) were determined from DSC thermograms. The Raman and DSC results were found to be correlated with the physical properties. In the optical absorption spectra six absorption bands were observed with different relative intensities at around 464, 522, 576, 742, 801 and 871 nm which are assigned to the transition of electrons from (ground state) 4I9/2 → G11/2; 4I9/2 → 2K3/2, 2G7/2; 4I9/2 → 4G5/2, 4G7/2; 4I9/2 → 4S3/2; 4F7/2 → 2H9/2, 4F5/2 and 4I9/2 → 2F3/2 respectively. From optical absorption data the energy band gap (Eopt) and Urbach energy (ΔE) were calculated.

High-resolution (>5 800 time-bandwidth product) shear mode TeO2 deflector

NASA Astrophysics Data System (ADS)

Soos, Jolanta I.; Caviris, Nicholas P.; Phuvan, Sonlinh

1992-12-01

Acousto-optic deflectors play an important role in optical signal processing systems due to their real time processing capabilities, as well as their conversion capabilities of a function of time to a function of space and time. In this work Brimrose investigated the design and fabrication of state-of-the-art, very large time-bandwidth acousto-optic devices from TeO2 single crystals.

Thermal, structural and optical properties of new TeO2sbnd Sb2O3sbnd GeO2 ternary glasses

NASA Astrophysics Data System (ADS)

Pereira, C.; Barbosa, J.; Cassanjes, F. C.; Gonçalves, R. R.; Ribeiro, S. J. L.; Poirier, G.

2016-12-01

In this work the novel glass system TeO2sbnd Sb2O3sbnd GeO2 was investigated and promising glass compositions were selected for further specific studies. Glass samples in the (80-0.8x)TeO2-(20-0.2x)Sb2O3-xGeO2 molar composition were prepared by the melt-quenching method with a glass-forming domain from x = 10 to x = 90. Samples were investigated by XRD, DSC, FTIR, Raman spectroscopy and UV-visible absorption. The XRD and DSC results bring informations about the non-crystalline state and thermal properties of these materials. It has been observed that higher GeO2 contents lead to higher glass transition temperatures and thermal stabilities against crystallization. FTIR and Raman spectroscopies suggest a progressive incorporation of GeO2 in the covalent network of TeO2 with conversion of structural units TeO4 to TeO3. Absorption spectra revealed the high visible transparency of these samples and an increase of the optical band gap with GeO2 addition, in agreement with a decreasing polarizability of the glass network. Er3+ doped and Er3+/Yb3+ codoped samples were also studied with respect to their infrared emission properties and higher GeO2 contents lead to an increase in IR emission intensity at 1,5 μm as well as longer radiative lifetimes. Finally, upconversion emission in the visible were also recorded and were shown to be strongly dependent of the composition.

Raman spectroscopy, thermal and optical properties of TeO2-ZnO-Nb2O5-Nd2O3 glasses.

PubMed

Kamalaker, V; Upender, G; Ramesh, Ch; Mouli, V Chandra

2012-04-01

The glasses with composition 75TeO2-10ZnO-(15-x)Nb2O5-xNd2O3 (0≤x≤9 mol%) were prepared using melt quenching method and their physical properties such as density (ρ), molar volume (VM), average crosslink density (nc¯), oxygen packing density (OPD) and number of bonds per unit volume (nb) were determined. Raman spectroscopic studies showed that the glass network consists of TeO4, TeO3+1, TeO3 and NbO6 units as basic structural units. The glass transition temperature (Tg), crystallization onset (To) and thermal stability (ΔT) were determined from DSC thermograms. The Raman and DSC results were found to be correlated with the physical properties. In the optical absorption spectra six absorption bands were observed with different relative intensities at around 464, 522, 576, 742, 801 and 871 nm which are assigned to the transition of electrons from (ground state) 4I9/2→G11/2; 4I9/2→2K3/2, 2G7/2; 4I9/2→4G5/2, 4G7/2; 4I9/2→4S3/2; 4F7/2→2H9/2, 4F5/2 and 4I9/2→2F3/2 respectively. From optical absorption data the energy band gap (Eopt) and Urbach energy (ΔE) were calculated. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis and electrochemical study of a hybrid structure based on PDMS-TEOS and titania nanotubes for biomedical applications

NASA Astrophysics Data System (ADS)

Castro, António G. B.; Bastos, Alexandre C.; Galstyan, Vardan; Faglia, Guido; Sberveglieri, Giorgio; Salvado, Isabel M. Miranda

2014-09-01

Metallic implants and devices are widely used in the orthopedic and orthodontic clinical areas. However, several problems regarding their adhesion with the living tissues and inflammatory responses due to the release of metallic ions to the medium have been reported. The modification of the metallic surfaces and the use of biocompatible protective coatings are two approaches to solve such issues. In this study, in order to improve the adhesion properties and to increase the corrosion resistance of metallic Ti substrates we have obtained a hybrid structure based on TiO2 nanotubular arrays and PDMS-TEOS films. TiO2 nanotubes have been prepared with two different diameters by means of electrochemical anodization. PDMS-TEOS films have been prepared by the sol-gel method. The morphological and the elemental analysis of the structures have been investigated by scanning electron microscopy and energy dispersive spectroscopy (EDS). Electrochemical impedance spectroscopy (EIS) and polarization curves have been performed during immersion of the samples in Kokubo’s simulated body fluid (SBF) at 37 °C to study the effect of structure layers and tube diameter on the protective properties. The obtained results show that the modification of the surface structure of TiO2 and the application of PDMS-TEOS film is a promising strategy for the development of implant materials.

Thermal analyses, spectral characterization and structural interpretation of Nd3+/Er3+ ions co-doped TeO2-ZnCl2 glasses system

NASA Astrophysics Data System (ADS)

Ahmed, Kasim F.; Ibrahim, Saeed O.; Sahar, Md. R.; Mawlud, Saman Q.; Khizir, Hersh A.

2017-09-01

The Nd3+/Er3+ ions co-doped in the system of zinc-tellurite with the composition of (70-2x)TeO2-30ZnCl2-xNd2O3-xEr2O3 concentration from 1.0 to 3.0 mol% (x=1, 2 and 3) glasses were prepared by using conventional melt-quenching technique. The amorphous nature of the glass been confirmed by using X-RAY Diffraction Spectroscopy. Thermal characteristic were determined using a DTA. The obtained results discussed in terms of the glass structure. The glass structure studied by means of FTIR. Seven significant vibrational peaks around 471, 687, 742, 768, 1632, 2833 and 3378 cm-1 which correspond to the structural bonding of the glass are observed in a range of 400-4000cm-1. The peaks observed are consistent with the stretching and bending vibrations of the Te-O, TeO4 trigonal bipyramids, TeO3 trigonal pyramids, Te-O-Te and OH linkages respectively.

The influence of TeO2 on thermal stability and 1.53 μm spectroscopic properties in Er(3+) doped oxyfluorite glasses.

PubMed

Wang, Fengchao; Cai, Muzhi; Chen, Rong; Jing, Xufeng; Li, Bingpeng; Tian, Ying; Zhang, Junjie; Xu, Shiqing

2015-11-05

In this work, the thermal and spectroscopic properties of Er(3+)-doped oxyfluorite glass based on AMCSBYT (AlF3-MgF2-CaF2-SrF2-BaF2-YF3-TeO2) system for different TeO2 concentrations from 6 to 21 mol% is reported. After adding a suitable content of TeO2, the thermal ability of glass improves significantly whose ΔT and S can reach to 118 °C and 4.47, respectively. The stimulated emission cross-section reaches to 7.80×10(-21) cm(2) and the fluorescence lifetime is 12.18 ms. At the same time, the bandwidth characteristics reach to 46.41×10(-21) cm(2) nm and the gain performance is 63.73×10(-21) cm(2) ms. These results show that the optical performances of this oxyfluorite glass are very well. Hence, AMCSBYT glass with superior performances might be a useful material for applications in optical amplifier around 1.53 μm. Copyright © 2015 Elsevier B.V. All rights reserved.

Ba 3 (Cr 0.97(1) Te 0.03(1) ) 2 TeO 9 : in Search of Jahn–Teller Distorted Cr(II) Oxide

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

Li, Man-Rong; Deng, Zheng; Lapidus, Saul H.

2016-10-17

A novel 6H - type hexagonal perovskite Ba 3 (Cr 0.97(1) Te 0.03 (1 ) ) 2 TeO 9 was prepared at high pressure (6 GPa) and temperature ( 1 773 K). Both transmission electron microscopy and synchrotron powder x - ray diffraction data demonstrate that Ba 3 (Cr 0.97(1) Te 0.03(1) ) 2 TeO 9 crystallize s in P6 3 / mmc with face - shared (Cr 0.97(1) Te 0.03(1) )O 6 octahedral pairs interconnected with TeO 6 octahedra via corner - sharing. Structure analysis shows a mixed Cr 2+ /Cr 3+ valence state with ~ 10% Cr 2+more » . The existence of Cr 2+ in Ba 3 (Cr 2+ 0.10(1) Cr 3+ 0.87(1) Te 6+ 0.03 ) 2 TeO 9 is further evidenced by x - ray absorption near edge spectr oscopy . Magnetic properties measurements show a paramagnetic response down to 4 K and a small glassy - state curvature at low temperature. In this work, the o ctahedral Cr 2+ O 6 component is stabilized in an oxide material for the first time ; the expected Jahn - Teller distortion of high - spin ( d 4 ) Cr 2+ is not found , which is attributed to the small proportion of Cr 2+ (~ 10%) and the face - sharing arrangement of CrO 6 octahedral pairs, that structu rally dis favor axial distortion.« less

The effects of Nd2O3 concentration in the laser emission of TeO2-ZnO glasses

NASA Astrophysics Data System (ADS)

Moreira, L. M.; Anjos, V.; Bell, M. J. V.; Ramos, C. A. R.; Kassab, L. R. P.; Doualan, D. J. L.; Camy, P.; Moncorgé, R.

2016-08-01

The present work reports the modification introduced by different Nd2O3 concentration on optical properties and the laser operation of Nd3+ doped (TeO2-ZnO) bulk tellurite glass. The spectroscopic data are analyzed within the Judd Ofelt formalism framework and the results are compared to the fluorescence lifetime and emission measurements to derive values for the quantum efficiency and the stimulated emission cross section of the considered 4F3/2 → 4I11/2 infrared laser transition around 1062.5 nm. Continuous-wave laser action is achieved with this bulk tellurite glass by pumping the sample inside a standard plan-concave mirror laser cavity with different output couplers. It is possible to observe coherent emission only for the lower concentration (0.5%(wt.) of Nd2 O3). Also laser action could only be observed for this sample with threshold pump power of 73 mW associated with a laser slope efficiency of 8% for an output coupler transmission of 4% indicating that TeO2-ZnO are potential materials for laser action. The results presented in this work together with those previously reported with higher concentration (1.0% (wt) of Nd2O3) determine the adequate Nd2O3 concentration for laser action and guide the correct experimental procedure for TeO2-ZnO glasses preparation.

Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

NASA Astrophysics Data System (ADS)

Haryadi, Sugianto, D.; Ristopan, E.

2015-12-01

Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm-1 and 3300 cm-1 respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10-2 S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.

Clinical evaluation of an over-the-counter hearing aid (TEO First®) in elderly patients suffering of mild to moderate hearing loss.

PubMed

Sacco, Guillaume; Gonfrier, Sébastien; Teboul, Bernard; Gahide, Ivan; Prate, Fredéric; Demory-Zory, Mathilde; Turpin, Jean-Michel; Vuagnoux, Claire; Genovese, Philippe; Schneider, Stéphane; Guérin, Olivier; Guevara, Nicolas

2016-07-09

Presbycusis has a direct influence on autonomy of the elderly but hearing aids lack of affordability. Moreover a recent review demonstrate that electroacoustic characteristics of OTC hearing aids were generally not suitable for the elderly people. In our study, we assessed the clinical value of a new over-the-counter (OTC) hearing aid device (TEO First®) in the elderly. This prospective monocentric open label study included patients over 60 years of age with a mild to moderate presbycusis. Patients were assessed with acceptable noise level test (ANL), pure tone (PTA) and speech (SA) audiometry in silent and noisy environment, with and without TEO First®. A Glasgow Hearing Aid Benefit Profile, acceptability and satisfaction surveys were completed after one month of using the device. Thirty one patients were included. There was an improvement of hearing with TEO First® in silence (SA: +39.2 %, p < 0.01; PTA: -9.04 dB, p < 0.01) or in noise (SA +47.7 %, p < 0.01; PTA: -5.23 dB, p < 0.05). After one month of use of the device, quality of life has improved with regards to the following parameters: decrease of perceived hearing difficulties during conversation without background noise (-9.6 % p = 0.018), in conversation with several people (-16.2 % p = 0.0076), decrease of negative emotions while watching TV (-18.5 % p = 0.011), during conversation without background noise (-16.5 % p = 0.0024), during conversation in noisy background (-17.1 % p = 0.027) and during conversation with several people (-20 % p = 0.014). The acceptability of the device was low to moderate. TEO First® is an effective OTC hearing aid that improves the patient's quality of life. Current Controlled Trials NCT01815788.

Complete event-by-event α /γ (β ) separation in a full-size TeO2 CUORE bolometer by Neganov-Luke-magnified light detection

NASA Astrophysics Data System (ADS)

Bergé, L.; Chapellier, M.; de Combarieu, M.; Dumoulin, L.; Giuliani, A.; Gros, M.; de Marcillac, P.; Marnieros, S.; Nones, C.; Novati, V.; Olivieri, E.; Paul, B.; Poda, D. V.; Redon, T.; Siebenborn, B.; Zolotarova, A. S.; Armengaud, E.; Augier, C.; Benoît, A.; Billard, J.; Broniatowski, A.; Camus, P.; Cazes, A.; Charlieux, F.; De Jesus, M.; Eitel, K.; Foerster, N.; Gascon, J.; Jin, Y.; Juillard, A.; Kleifges, M.; Kozlov, V.; Kraus, H.; Kudryavtsev, V. A.; Le Sueur, H.; Maisonobe, R.; Navick, X.-F.; Pari, P.; Queguiner, E.; Rozov, S.; Sanglard, V.; Vagneron, L.; Weber, M.; Yakushev, E.

2018-03-01

In the present work, we describe the results obtained with a large (≈133 cm3 ) TeO2 bolometer, with a view to a search for neutrinoless double-β decay (0 ν β β ) of 130Te. We demonstrate an efficient α -particle discrimination (99.9%) with a high acceptance of the 0 ν β β signal (about 96%), expected at ≈2.5 MeV. This unprecedented result was possible thanks to the superior performance (10-eV rms baseline noise) of a Neganov-Luke-assisted germanium bolometer used to detect a tiny (70-eV) light signal from the TeO2 detector, dominated by γ (β )-induced Cherenkov radiation but exhibiting also a clear scintillation component. The obtained results represent a major breakthrough toward the TeO2-based version of the CUORE Upgrade with Particle IDentification (CUPID), a ton-scale cryogenic 0 ν β β experiment proposed as a followup to the Cryogenic Underground Observatory for Rare Events (CUORE) project with particle identification. The CUORE experiment recently began a search for neutrinoless double-β decay of 130Te with an array of 988 125-cm3TeO2 bolometers. The lack of α discrimination in CUORE makes α decays at the detector surface the dominant background component, at the level of ≈0.01 counts/(keV kg y) in the region of interest. We show here, for the first time with a CUORE-size bolometer and using the same technology as CUORE for the readout of both heat and light signals, that surface α background can be fully rejected.

Impact of the new equation of state of seawater (TEOS-10) on the estimates of water mass mixture and meridional transport in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Almeida, Lucas; de Azevedo, José Luiz Lima; Kerr, Rodrigo; Araujo, Moacyr; Mata, Mauricio M.

2018-03-01

The equation of state of seawater (EOS) provides a simple way to link the properties of seawater that are the most important for ocean dynamics and the ocean-atmosphere climate system. In 2010, the set of equations used to derive all thermodynamic properties of seawater were updated using a thermodynamic approach. The new approach, named TEOS-10, results in better estimates of seawater properties, such as salinity and temperature, when compared to the previous EOS version (EOS-80). Since several physical processes in the oceans are driven by these properties, improvements in the EOS performance are expected to lead to a better and more realistic representation of the ocean. This work focuses on assessing the main differences of the: (i) contribution of water masses to a total mixture, (ii) baroclinic velocity, and (iii) volume and heat transport, as calculated by the EOS-80 and by the TEOS-10, along four zonal transects at 26.5°N, 10°N, 11°S, and 34.5°S in the Atlantic Ocean. The density differences (always between TEOS-10 and EOS-80) increase with depth and hence the results indicate that the most significant difference in the water mass contributions was found for Antarctic Bottom Water. Within that layer, the differences reach up to 10% on its fraction of the mixture when calculated by the TEOS-10, although the difference in the North Atlantic Deep Water contribution was not negligible either. The estimated baroclinic velocities showed considerable differences in all studied areas, being more significant over boundary current systems. The Gulf Stream presented lower velocity, while the Brazil Current presented increasing velocity when using TEOS-10. The comparison between values computed for volume transported by the Atlantic Meridional Overturning Circulation showed a total difference of about +6%, which cannot be neglected when considering the space and time variability involved. The heat transport showed significant differences in the study areas at the

Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

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

Haryadi,, E-mail: haryadi@polban.ac.id; Sugianto, D.; Ristopan, E.

2015-12-29

Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for aboutmore » 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm{sup −1} and 3300 cm{sup −1} respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10{sup −2} S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.« less

β-Na2TeO4: Phase Transition from an Orthorhombic to a Monoclinic Form. Reversible CO2 Capture.

PubMed

Galven, Cyrille; Pagnier, Thierry; Rosman, Noël; Le Berre, Françoise; Crosnier-Lopez, Marie-Pierre

2018-06-18

The present work concerns the tellurate Na 2 TeO 4 which has a 1D structure and could then present a CO 2 capture ability. It has been synthesized in a powder form via a solid-state reaction and structurally characterized by thermal X-ray diffraction experiments, Raman spectroscopy, and differential scanning calorimetry. The room temperature structure corresponds to the β-Na 2 TeO 4 orthorhombic form, and we show that it undergoes a reversible structural transition near 420 °C toward a monoclinic system. Ab initio computations were also performed on the room temperature structure, the Raman vibration modes calculated, and a normal mode attribution proposed. In agreement with our expectations, this sodium oxide is able to trap CO 2 by a two-step mechanism: Na + /H + exchange and carbonation of the released sodium as NaHCO 3 . This capture is reversible since CO 2 can be released upon heating by recombination of the mother phase.

TeO2 slow surface acoustic wave Bragg cell

NASA Astrophysics Data System (ADS)

Yao, Shi-Kay

1991-08-01

A newly discovered slow acoustic surface wave (SAW) on a (-110) cut TeO2 surface is reported focusing on its properties studied using a PC based numerical method. It is concluded that the slow SAW is rather tolerant to crystal surface orientation errors and has unusually deep penetration of its shear component into the thickness of substrate, about 47 wavelengths for a half amplitude point. The deep shear field is considered to be beneficial for surface acoustooptic interaction with free propagating focused laser beams. Rotation of the substrate about the z-axis makes it possible to adjust a slow SAW velocity with the potential advantage of trading acoustic velocity for less acoustic attenuation. Wider-bandwidth long signal processing time Bragg cells may be feasible utilizing this trade-off. The slow SAW device is characterized by an extremely low power consumption which might be useful for compact portable or avionics signal processing equipment applications.

In vitro genotoxicity assessment of MTES, GPTES and TEOS, three precursors intended for use in food contact coatings.

PubMed

Lionti, Krystelle; Séverin, Isabelle; Dahbi, Laurence; Toury, Bérangère; Chagnon, Marie-Christine

2014-03-01

Organoalkoxysilanes are precursors that are used increasingly in the synthesis of food contact coatings. To comply with the EU regulation, their potential toxicity must be assessed, and very little information is known. The genotoxicity of three common precursors was studied, namely, tetraethylorthosilicate (TEOS), methyltriethoxysilane (MTES) and 3-glycidyloxypropyltriethoxysilane (GPTES). By the Ames test, MTES and TEOS were not mutagenic for bacteria. A significant positive response was observed with GPTES in the TA100 and TA1535 strains. The mutagenic effect was more pronounced in the presence of the exogenous metabolic activation system with an increase of the induction factor (ten-fold higher for the TA1535 strain). In the micronucleus assay performed with a human hepatoma cell line (HepG2 cells), GPTES gave negative results even in the presence of an exogenous activation system. To ascertain the possibility of using this precursor in food contact material, its migration must be monitored according to the coating formulation because migration might result in hazardous human exposure. Copyright © 2014. Published by Elsevier Ltd.

Multilevel population genetic analysis of vanA and vanB Enterococcus faecium causing nosocomial outbreaks in 27 countries (1986-2012).

PubMed

Freitas, Ana R; Tedim, Ana P; Francia, Maria V; Jensen, Lars B; Novais, Carla; Peixe, Luísa; Sánchez-Valenzuela, Antonio; Sundsfjord, Arnfinn; Hegstad, Kristin; Werner, Guido; Sadowy, Ewa; Hammerum, Anette M; Garcia-Migura, Lourdes; Willems, Rob J; Baquero, Fernando; Coque, Teresa M

2016-12-01

Vancomycin-resistant Enterococcus faecium (VREfm) have been increasingly reported since the 1980s. Despite the high number of published studies about VRE epidemiology, the dynamics and evolvability of these microorganisms are still not fully understood. A multilevel population genetic analysis of VREfm outbreak strains since 1986, representing the first comprehensive characterization of plasmid content in E. faecium, was performed to provide a detailed view of potential transmissible units. From a comprehensive MeSH search, we identified VREfm strains causing hospital outbreaks (1986-2012). In total, 53 VanA and 18 VanB isolates (27 countries, 5 continents) were analysed and 82 vancomycin-susceptible E. faecium (VSEfm) were included for comparison. Clonal relatedness was established by PFGE and MLST (goeBURST/Bayesian Analysis of Population Structure, BAPS). Characterization of van transposons (PCR mapping, RFLP, sequencing), plasmids (transfer, ClaI-RFLP, PCR typing of relaxases, replication-initiation proteins and toxin-antitoxin systems, hybridization, sequencing), bacteriocins and virulence determinants (PCR, hybridization, sequencing) was performed. VREfm were mainly associated with major human lineages ST17, ST18 and ST78. VREfm and VSEfm harboured plasmids of different families [RCR, small theta plasmids, RepA_N (pRUM/pLG1) and Inc18] able to yield mosaic elements. Tn1546-vanA was mainly located on pRUM/Axe-Txe (USA) and Inc18-pIP186 (Europe) plasmids. The VanB2 type (Tn5382/Tn1549) was predominant among VanB strains (chromosome and plasmids). Both strains and plasmids contributed to the spread and persistence of vancomycin resistance among E. faecium. Horizontal gene transfer events among genetic elements from different clonal lineages (same or different species) result in chimeras with different stability and host range, complicating the surveillance of epidemic plasmids. © The Author 2016. Published by Oxford University Press on behalf of the British

Spectroscopic and optical properties of the VO2+ ion doped TeO2-TiO2-ZnO-Nb2O5 glass system

NASA Astrophysics Data System (ADS)

Swapna; Upender, G.; Sreenivasulu, V.; Prasad, M.

2016-04-01

Studies such as optical absorption, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Electron paramagnetic resonance (EPR) spectroscopy and Differential scanning calorimetry (DSC) were carried out on VO2+ ion doped TeO2-TiO2-ZnO-Nb2O5 glass system. Raman and FTIR spectra of the glasses revealed the presence of [TeO3], [TeO4] and [NbO6] structural units in the glass network. The Urbach energy (Δ E), cut-off wavelength (λ c ), optical band gap ( E opt ), optical basicity (Λ) and electron polarizability ( α) of the glasses were determined from optical absorption studies. The density ( ρ), molar volume ( V m ), oxygen molar volume ( V o ) and refractive index ( n) were also measured. Spin-Hamiltonian parameters were calculated from the EPR studies. When Nb2O5 was increased at the expense of ZnO, the density, optical band gap and Urbach energy of the glasses increased, and the electronic polarizability and optical basicity decreased. The EPR spectra clearly showed that vanadium was in the glass as VO2+ and occupied octahedral sites with tetrahedral compression. Spin-Hamiltonian parameters g‖ and g⊥ decreased as Nb2O5 content increased in the glass. The glass transition temperature ( T g ) also increased with increasing Nb2O5 content in the glass.

Synthesis, structural, thermal and optical properties of TeO2-Bi2O3-GeO2-Li2O glasses

NASA Astrophysics Data System (ADS)

Dimowa, Louiza; Piroeva, Iskra; Atanasova-Vladimirova, S.; Petrova, Nadia; Ganev, Valentin; Titorenkova, Rositsa; Yankov, Georgi; Petrov, Todor; Shivachev, Boris L.

2016-10-01

In this study, synthesis and characterization of novel quaternary tellurite glass system TeO2-Bi2O3-GeO2-Li2O is presented. The compositions include TeO2 and GeO2 as glass formers while different proportion of Bi2O3 and Li2O act as network modifiers. Differential thermal analysis, X-ray diffraction, scanning electron microscopy energy dispersive X-ray spectroscopy, laser ablation inductively coupled plasma mass spectrometry, UV-Vis and Raman spectroscopy are applied to study the structural, thermal and optical properties of the studied glasses. Obtained glasses possess a relatively low glass transition temperature (around 300 °C) if compared to other tellurite glasses, show good thermal transparency in the visible and near infra-red (from 2.4 to 0.4 μm) and can double the frequency of laser light from its original wavelength of 1064 nm to its second-harmonic at 532 nm (i.e. second harmonic generation).

Synthesis and characterization of the NiFe2O4@TEOS-TPS@Ag nanocomposite and investigation of its antibacterial activity

NASA Astrophysics Data System (ADS)

Allafchian, Ali R.; Jalali, S. A. H.; Amiri, R.; Shahabadi, Sh.

2016-11-01

In this study, the NiFe2O4 was embedded in (3-mercaptopropyl) trimethoxysilane (TPS) and tetraethyl orthosilicate (TEOS) using the sol-gel method. These compounds were used as the support of Ag nanoparticles (Ag NPs). The NiFe2O4@TEOS-TPS@Ag nanocomposites were obtained with the development of bonding between the silver atoms of Ag NPs and the sulfur atoms of TPS molecule. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used for the characterization of the Ag nanocomposites. Also, the magnetic properties of these nanocomposites were studied by using a vibrating sample magnetometer (VSM) technique. The disk diffusion, minimum inhibition concentration (MIC) and minimum bactericidal concentrations (MBC) tests were used for the investigation of the antibacterial effect of this nanocomposite against bacterial strains. The synthesized nanocomposite presented high reusability and good antibacterial activity against gram-positive and gram-negative bacteria. Remarkably, this nanocomposite could be easily removed from the disinfected media by magnetic decantation.

Synthesis, characterization and tin/copper-nitrogen substitutional effect on photocatalytic activity of honeycomb ordered P2-Na2Ni2TeO6

NASA Astrophysics Data System (ADS)

Kadari, Ramaswamy; Velchuri, Radha; Sreenu, K.; Ravi, Gundeboina; Munirathnam, Nagegownivari R.; Vithal, Muga

2016-11-01

We have successfully prepared visible light active tin/copper-nitrogen co-doped honeycomb ordered P2-Na2Ni2TeO6 photocatalysts by solid state/ion exchange methods. Powder XRD, TG analysis, SEM, surface area, O-N-H analysis, ICP-OES, FT-IR and UV-DRS measurements are employed to characterize all the samples. All the doped compositions adopted hexagonal lattice with space group P63/mcm. The photocatalytic activity of all the samples was studied against the degradation of methyl violet (MV) and methylene blue (MB) under visible light irradiation. The variation of the photocatalytic activity due to the substitution of cation, anion and co-doping in Na2Ni2TeO6 is investigated. Co-doped samples have exhibited higher activity compared to rest of the materials. The role of reactive intermediate species in the photocatalytic degradation of dyes is also studied using appropriate scavengers.

Mass loss of TEOS-coated RCC subjected to the environment at the shuttle wing leading edge

NASA Technical Reports Server (NTRS)

Stroud, C. W.; Rummler, D. R.

1981-01-01

Coated, reinforced carbon-carbon (RCC) is used for the leading edges of the Space Shuttle. The mass loss characteristics of RCC specimens coated with tetra-ethyl-ortho-silicate (TEOS) were determined for conditions which simulated the entry environment expected at the stagnation area of the wing leading edge. Maximum specimen temperature was 1632 K. Specimens were exposed for up to 100 missions. Stress levels up to 8.274 MPa caused an average increase in oxidation of 6 percent over unstressed specimens. Experimentally determined mass losses were compared with those predicted by an existing empirical analysis.

Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses for ∼1.2 μm laser applications

NASA Astrophysics Data System (ADS)

Wang, Shunbin; Li, Chengzhi; Yao, Chuanfei; Jia, Shijie; Jia, Zhixu; Qin, Guanshi; Qin, Weiping

2017-02-01

Intense ∼1.2 μm fluorescence is observed in Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses under 915 nm laser diode excitation. The 1.2 μm emission can be ascribed to the transition 5I6→5I8 of Ho3+. With the introducing of BaF2, the content of OH in the glasses drops markedly, and the 1.2 μm emission intensity increases gradually as increasing the concentration percentage of BaF2. Furthermore, microstructured fibers based on the TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method, and a relative positive gain of ∼9.42 dB at 1175.3 nm is obtained in a 5 cm long fiber.

Synthesized af-PFCl and GG-g-P(AN)/TEOS hydrogel composite used in hybridized technique applied for AMD treatment

NASA Astrophysics Data System (ADS)

Fosso-Kankeu, Elvis

2018-06-01

In the present study af-PFCl, GL-g-P(AN) hydrogel and GL-g-P(AN)/TEOS hydrogel composite were synthesized. The hydrogels were characterized using the fourier transformed infra-red (FTIR) and the scanning electron microscope (SEM) techniques. The coagulant af-PFCl and the hydrogels were applied consecutively in flocculation and adsorption processes respectively for the treatment of acid mine drainage (AMD). It was observed that the grafting process increased the amount of binding groups on the hydrogels. The hybridization of the techniques assisted in the removal of anions; while the cations were mostly removed by the adsorption process. The adsorbents behaviour was fittingly expressed by the pseudo-second order model. The adsorption capacities of GL-g-P(AN)/TEOS hydrogel composite for the removal of Al, As and Zn were 3.89, 0.66 and 0.394 respectively; while the adsorption capacities of GL-g-P(AN) for the removal of Al and Mg were 3.47 and 9.66 mg/g respectively. The techniques applied in this study have shown good potential for the removal of specific pollutants from the AMD; it is however, important that the appropriate hybridization of techniques allows to remove all the pollutants and restore acceptable water quality.

A Study on Anti – Fouling Behaviour and Mechanical Properties of PVA/Chitosan/TEOS Hybrid membrane in The Treatment of Copper Solution

NASA Astrophysics Data System (ADS)

Sulaiman, N. A.; Kassim Shaari, N. Z.; Rahman, N. Abdul

2018-05-01

In a wastewater treatment by using membrane filtration, fouling has been one of the major problems. In this study, the anti-fouling behaviour of the fabricated thin-film composite membrane were studied during the treatment of water containing copper ion. The membranes were prepared from a polymer blend of 2wt.% chitosan with 10 wt.% poly(vinyl alcohol) (PVA) and then it was cross – linked with tetraethylorthosilicate (TEOS) through sol-gel method. The membrane had been evaluated for its resistance against organic fouling where humic acid had been chosen as organic foulant model which represent the natural organic matter (NOM) in water or wastewater. The dead-end filtration experiments were carried out by using 50 ppm of copper solution with and without the presence of humic acid as feed solution, which was passed through two types of thin film composite membranes. The possible reversible fouling was evaluated by using relative flux decay (RFD) and relative flux recovery (RFR) calculations. The percentage of copper ion removal was evaluated by using Atomic Absorption Spectroscopy (AAS). Based on the results, with the presence of humic acid, the membrane incorporated with silica precursor (TEOS) showed lower flux decay (3%) and higher flux recovery (76%), which show that the formulated hybrid membrane possesses the anti fouling property. The same trend was observed in the mechanical properties of hybrid membrane, where the presence of TEOS has improved the tensile strength and flexibility of the membrane. Therefore, the fabricated thin film composite with the anti-fouling properties and good physical flexibility has potential to be used in the treatment of wastewater containing heavy metal as it could result in good saving in term of operational cost.

Evaluation of tetraethoxysilane (TEOS) sol-gel coatings, modified with green synthesized zinc oxide nanoparticles for combating microfouling.

PubMed

Krupa, A Nithya Deva; Vimala, R

2016-04-01

Green synthesis of zinc oxide nanoparticles (ZnO-NPs) is gaining importance as an eco-friendly alternative to conventional methods due to its enormous applications. The present work reports the synthesis of ZnO-NPs using the endosperm of Cocos nucifera (coconut water) and the bio-molecules responsible for nanoparticle formation have been identified. The synthesized nanoparticles were characterized using UV-Visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Zeta potential measurement. The results obtained reveal that the synthesized nanoparticles are moderately stable with the size ranging from 20 to 80 nm. The bactericidal effect of the nanoparticles was proved by well diffusion assay and determination of minimum inhibitory concentration (MIC) against marine biofilm forming bacteria. Further the green synthesized ZnO-NPs were doped with TEOS sol-gels (TESGs) in order to assess their antimicrofouling capability. Different volumes of liquid sol-gels were coated on to 96-well microtitre plate and cured under various conditions. The optimum curing conditions were found to be temperature 60 °C, time 72 h and volume 200 μl. Antiadhesion test of the undoped (SG) and ZnO-NP doped TEOS sol-gel (ZNSG) coatings were evaluated using marine biofilm forming bacteria. ZNSG coatings exhibited highest biofilm inhibition (89.2%) represented by lowest OD value against Pseudomonasotitidis strain NV1. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative studies on the room-temperature ferrielectric and ferrimagnetic Ni3TeO6-type A2FeMoO6 compounds (A = Sc, Lu)

PubMed Central

Song, Guang; Zhang, Weiyi

2016-01-01

First-principles calculations have been carried out to study the structural, electric, and magnetic properties of Ni3TeO6-type A2FeMoO6 compounds (A = Sc, Lu). Their electric and magnetic properties behave like room-temperature ferrielectric and ferrimagnetic insulators where polarization comes from the un-cancelled antiparallel dipoles of (A(1), Fe3+) and (A(2), Mo3+) ion groups, and magnetization from un-cancelled antiparallel moments of Fe3+ and Mo3+ ions. The net polarization increases with A’s ionic radius and is 7.1 and 8.7 μCcm−2 for Sc2FeMoO6 and Lu2FeMoO6, respectively. The net magnetic moment is 2 μB per formula unit. The magnetic transition temperature is estimated well above room-temperature due to the strong antiferromagnetic superexchange coupling among Fe3+ and Mo3+ spins. The estimated paraelectric to ferrielectric transition temperature is also well above room-temperature. Moreover, strong magnetoelectric coupling is also anticipated because the magnetic ions are involved both in polarization and magnetization. The fully relaxed Ni3TeO6-type A2FeMoO6 structures are free from soft-phonon modes and correspond to stable structures. As a result, Ni3TeO6-type A2FeMoO6 compounds are possible candidates for room-temperature multiferroics with large magnetization and polarization. PMID:26831406

Analysis of Te and TeO 2 on CdZnTe Nuclear Detectors Treated with Hydrogen Bromide and Ammonium-Based Solutions

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

Drabo, Mebougna L.; Egarievwe, Stephen U.; Okwechime, Ifechukwude O.

Surface defects caused during cutting and polishing in the fabrication of cadmium zinc telluride (CdZnTe) nuclear detectors limit their spectral performance. Chemical treatments are often used to remove surface damages and defects. In this paper, we present the analysis of Te and TeO 2 species on the surfaces of CdZnTe nuclear detectors treated with hydrogen bromide and ammonium-based solutions. The CdZnTe wafers were chemo-mechanically polished in a mixture of hydrogen bromide in hydrogen peroxide and ethylene glycol, followed by a chemical passivation in a mixture of ammonium fluoride and hydrogen peroxide solution. X-ray photoelectron spectroscopy showed significant conversion of Temore » to TeO 2, thus producing a more chemically stable surface. The resistivity of the CdZnTe samples is in the order of 1010 ohms-cm. The current for a given applied voltage increased following the passivation and decreased after a 3-hour period. Results from spectral response measurements showed that the 59.5-keV gamma-peak of Am-241 was stable under the same channel for the surface treatment processes.« less

Analysis of Te and TeO 2 on CdZnTe Nuclear Detectors Treated with Hydrogen Bromide and Ammonium-Based Solutions

DOE PAGES

Drabo, Mebougna L.; Egarievwe, Stephen U.; Okwechime, Ifechukwude O.; ...

2017-04-30

Surface defects caused during cutting and polishing in the fabrication of cadmium zinc telluride (CdZnTe) nuclear detectors limit their spectral performance. Chemical treatments are often used to remove surface damages and defects. In this paper, we present the analysis of Te and TeO 2 species on the surfaces of CdZnTe nuclear detectors treated with hydrogen bromide and ammonium-based solutions. The CdZnTe wafers were chemo-mechanically polished in a mixture of hydrogen bromide in hydrogen peroxide and ethylene glycol, followed by a chemical passivation in a mixture of ammonium fluoride and hydrogen peroxide solution. X-ray photoelectron spectroscopy showed significant conversion of Temore » to TeO 2, thus producing a more chemically stable surface. The resistivity of the CdZnTe samples is in the order of 1010 ohms-cm. The current for a given applied voltage increased following the passivation and decreased after a 3-hour period. Results from spectral response measurements showed that the 59.5-keV gamma-peak of Am-241 was stable under the same channel for the surface treatment processes.« less

Effects of tetraethyl orthosilicate (TEOS) on the light and temperature stability of a pigment from Beta vulgaris and its potential food industry applications.

PubMed

Molina, Gustavo A; Hernández-Martínez, Angel Ramon; Cortez-Valadez, Manuel; García-Hernández, Fernando; Estevez, Miriam

2014-11-05

A novel, simple and inexpensive modification method using TEOS to increase the UV light, pH and temperature stability of a red-beet-pigment extracted from Beta vulgaris has been proposed. The effects on the molecular structure of betalains were studied by FTIR spectroscopy. The presence of betacyanin was verified by UV-Vis spectroscopy and its degradation in modified red-beet-pigment was evaluated and compared to the unmodified red-beet-pigment; performance improvements of 88.33%, 16.84% and 20.90% for UV light, pH and temperature stability were obtained, respectively,. Measurements of reducing sugars, phenol, and antioxidant contents were performed on unmodified and modified red-beet-pigment and losses of close to 21%, 54% and 36%, respectively, were found to be caused by the addition of TEOS. Polar diagrams of color by unmodified and modified red-beet-pigment in models of a beverage and of a yogurt were obtained and the color is preserved, although here is a small loss in the chromaticity parameter of the modified red-beet-pigment.

Magnetic properties of the honeycomb oxide Na 2 Co 2 TeO 6

DOE PAGES

Lefrançois, E.; Songvilay, M.; Robert, J.; ...

2016-12-14

We have studied the magnetic properties of Na 2 Co 2 TeO 6 , which features a honeycomb lattice of magnetic Co 2 + ions, through macroscopic characterization and neutron diffraction on a powder sample. We also show that this material orders in a zigzag antiferromagnetic structure. Additionally by allowing a linear magnetoelectric coupling, this magnetic arrangement displays very peculiar spatial magnetic correlations, larger in the honeycomb planes than between the planes, which do not evolve with the temperature. We have investigated this behavior by classical Monte Carlo calculations using the J 1 - J 2 - Jmore » 3 model on a honeycomb lattice with a small interplane interaction. Furthermore, our model reproduces the experimental neutron structure factor, although its absence of temperature evolution must be due to additional ingredients, such as chemical disorder or quantum fluctuations enhanced by the proximity to a phase boundary.« less

Periodicity, Electronic Structures, and Bonding of Gold Tetrahalides [AuX4](-) (X = F, CI, Br, I, At, Uus)

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

Li, Wan-Lu; Li, Yong; Xu, Congqiao

2015-12-07

Systematic theoretical and experimental investigations have been performed to understand the periodicity and electronic structures of trivalent-gold halides using gold tetrahalides [AuX4]⁻ anions (X = F, Cl, Br, I, At, Uus). The [AuX4]⁻ (X = Cl, Br, I) anions were produced in gas phase and their negative-ion photoelectron spectra were obtained, which exhibited rich and well-resolved spectral peaks. We calculated the adiabatic as well as vertical electron detachment energies using density functional methods with scalar and spin-orbit coupling relativistic effects. The simulated photoelectron spectra based on these calculations are in good agreement with the experimental spectra. Our results show thatmore » the trivalent Au(III) oxidation state becomes progressively less stable while Au(I) is preferred when the halides become heavier along the Period Table. This trend reveals that the oxidation state of metals in complexes can be manipulated through ligand design« less

Visible light driven multifunctional photocatalysis in TeO2-based semiconductor glass ceramics

NASA Astrophysics Data System (ADS)

Kushwaha, Himmat Singh; Thomas, Paramanandam; Vaish, Rahul

2017-01-01

Photocatalytic xCaCu3Ti4O12-(100-x)TeO2 (x=0.25 mol% to 3 mol%), glass nanocomposites were fabricated and investigated for wastewater treatment, self-cleaning surfaces, and photocatalytic hydrogen evolution. Visible light active crystals of Cu-doped TiO2 and TiTe3O8 were grown by optimized crystallization of as-quenched glasses. The visible light photocatalytic activity of glass samples was investigated for estrogenic pharmaceutical pollutants, and the degradation rate was obtained as 168.56 min-1 m-2. A higher photocatalytic H2 production rate was observed (135 μmole h-1 g-1) for the crystallized CaCu3Ti4O12-TeO2 (x=3. 0) glass plate under visible light. The self-cleaning performance was observed using contact angle measurements for water under dark and light conditions. These visible light active glass ceramics are a cost effective sustainable solution for water treatment and self-cleaning applications.

Thermoelectric Power Measurements of xSb-(60- x)V2O5-40TeO2 Glasses

NASA Astrophysics Data System (ADS)

Souri, Dariush; Siahkali, Zahra; Moradi, Mohammad

2016-01-01

Bulk xSb-(60- x)V2O5-40TeO2 glass systems (with 0 ≤ x ≤ 15 in mol.%) were prepared by using the standard melt quenching procedure, and their Seebeck coefficients, S, were measured within the temperature range of 250-470 K. For the understudied samples, the thermoelectric powers at typical temperatures of 296 K, 370 K and 407 K were measured, and were in the ranges (-405) to (-698) μVK-1, (-394) to (-685) μVK-1 and (-392) to (-691) μVK-1, respectively. The selection of typical temperatures aims at the evaluation of the trend of figure of merit in these glasses. Based on the negative sign of S, the present glasses were found to be n-type semiconductors; also, the experimental relationship between S and C V ( C V = [V4+]/ V tot is the ratio of the content of reduced vanadium ions) satisfied the theoretical Heikes formula, relating S to ln( C V/1 - C V), and also the Mackenzie formula, relating S to ln([V5+]/[V4+]). The parameter α^' in Heikes formula was determined to be ≪1 and so the small polaron hopping conduction mechanism was certified to occur in these glasses; this result confirms the previously reported results of direct current (DC) electrical conduction experiments on the same samples. Results of thermoelectric measurements show the compositional dependence of S on Sb content and C V, indicating that S increases with the increase in Sb content; these results show that the dominant factor determining S is C V. Also, figure of merit was determined for these glasses, which show the highest value for 60V2O5-40TeO2 glass system, as a good candidate in thermoelectric applications.

Resolved discrepancies between visible spontaneous Raman cross-section and direct near-infrared Raman gain measurements in TeO2-based glasses.

PubMed

Rivero, Clara; Stegeman, Robert; Couzi, Michel; Talaga, David; Cardinal, Thierry; Richardson, Kathleen; Stegeman, George

2005-06-13

Disagreements on the Raman gain response of different tellurite-based glasses, measured at different wavelengths, have been recently reported in the literature. In order to resolve this controversy, a multi-wavelength Raman cross-section experiment was conducted on two different TeO2-based glass samples. The estimated Raman gain response of the material shows good agreement with the directly-measured Raman gain data at 1064 nm, after correction for the dispersion and wavelength-dependence of the Raman gain process.

Competitive Adsorption and Oxidation Behavior of Heavy Metals on nZVI Coated with TEOS.

PubMed

Eglal, Mahmoud M; Ramamurthy, Amruthur S

2015-11-01

Zero valent iron nanoparticle (nanofer ZVI) is a powerful substance due to its coating with tetraethyl orthosilicate (TEOS). Tetraethyl orthosilicate imparts higher reactivity and decreases particle agglomeration. The competitive removal and displacement of multi-metals are influenced by time, pH, and initial concentration, the presence and properties of competing metals ion in the solution. For both the isotherm and kinetic studies performed for multi-metal removal experiments, compared to Pb II and Cd II, Cu II experienced a higher removal rate during the initial 5 minutes. After 120 minutes, all metals achieved removal efficiency in the range of 95 to 99%. The results of single and competitive kinetic tests for all three metals during the initial 5 minutes indicated that the presence of other metals generally reduce removal efficiency of metals. Both kinetic test and electron dispersive spectroscope (EDS) studies found that Cu II gets removed faster than the other metals. Pseudo-second order behavior was noted for the multi-metal removal systems.

Enriched TeO 2 bolometers with active particle discrimination: Towards the CUPID experiment

DOE PAGES

Artusa, D. R.; Avignone, F. T.; Beeman, J. W.; ...

2017-04-01

We present the performances of two 92% enriched 130TeO2 crystals operated as thermal bolometers in view of a next generation experiment to search for neutrinoless double beta decay of 130Te. The crystals, 435 g each, show an energy resolution, evaluated at the 2615 keV γ-line of 208Tl, of 6.5 and 4.3 keV FWHM. The only observable internal radioactive contamination arises from 238U (15 and 8 μBq/kg, respectively). The internal activity of the most problematic nuclei for neutrinoless double beta decay, 226Ra and 228Th, are both evaluated as <3.1 μBq/kg for one crystal and <2.3 μBq/kg for the second. Thanks tomore » the readout of the weak Cherenkov light emitted by β/γ particles by means of Neganov–Luke bolometric light detectors we were able to perform an event-by-event identification of β/γ events with a 95% acceptance level, while establishing a rejection factor of 98.21% and 99.99% for α particles.« less

Enriched TeO 2 bolometers with active particle discrimination: Towards the CUPID experiment

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

Artusa, D. R.; Avignone, F. T.; Beeman, J. W.

We present the performances of two 92% enriched 130TeO2 crystals operated as thermal bolometers in view of a next generation experiment to search for neutrinoless double beta decay of 130Te. The crystals, 435 g each, show an energy resolution, evaluated at the 2615 keV γ-line of 208Tl, of 6.5 and 4.3 keV FWHM. The only observable internal radioactive contamination arises from 238U (15 and 8 μBq/kg, respectively). The internal activity of the most problematic nuclei for neutrinoless double beta decay, 226Ra and 228Th, are both evaluated as <3.1 μBq/kg for one crystal and <2.3 μBq/kg for the second. Thanks tomore » the readout of the weak Cherenkov light emitted by β/γ particles by means of Neganov–Luke bolometric light detectors we were able to perform an event-by-event identification of β/γ events with a 95% acceptance level, while establishing a rejection factor of 98.21% and 99.99% for α particles.« less

Characterization of emission properties of Er3+ ions in TeO2-CdF2-WO3 glasses.

PubMed

Bilir, G; Mustafaoglu, N; Ozen, G; DiBartolo, B

2011-12-01

TeO(2)-CdF(2)-WO(3) glasses with various compositions and Er(3+) concentrations were prepared by conventional melting method. Their optical properties were studied by measuring the absorption, luminescence spectra and the decay patterns at room temperature. From the optical absorption spectra the Judd-Ofelt parameters (Ω(t)), transition probabilities, branching ratios of various transitions, and radiative lifetimes were calculated. The absorption and emission cross-section spectra of the (4)I(15/2) to (4)I(13/2) transition of erbium were determined. Emission quantum efficiencies and the average critical distance R(0) which provides a measure for the strength of cross relaxation were determined. Copyright © 2011 Elsevier B.V. All rights reserved.

Molecular Analysis of VanA Outbreak of Enterococcus faecium in Two Warsaw Hospitals: The Importance of Mobile Genetic Elements

PubMed Central

Wardal, Ewa; Markowska, Katarzyna; Żabicka, Dorota; Wróblewska, Marta; Giemza, Małgorzata; Mik, Ewa; Połowniak-Pracka, Hanna; Woźniak, Agnieszka; Hryniewicz, Waleria; Sadowy, Ewa

2014-01-01

Vancomycin-resistant Enterococcus faecium represents a growing threat in hospital-acquired infections. Two outbreaks of this pathogen from neighboring Warsaw hospitals have been analyzed in this study. Pulsed-field gel electrophoresis (PFGE) of SmaI-digested DNA, multilocus VNTR analysis (MLVA), and multilocus sequence typing (MLST) revealed a clonal variability of isolates which belonged to three main lineages (17, 18, and 78) of nosocomial E. faecium. All isolates were multidrug resistant and carried several resistance, virulence, and plasmid-specific genes. Almost all isolates shared the same variant of Tn1546 transposon, characterized by the presence of insertion sequence ISEf1 and a point mutation in the vanA gene. In the majority of cases, this transposon was located on 50 kb or 100 kb pRUM-related plasmids, which lacked, however, the axe-txe toxin-antitoxin genes. 100 kb plasmid was easily transferred by conjugation and was found in various clonal backgrounds in both institutions, while 50 kb plasmid was not transferable and occurred solely in MT159/ST78 strains that disseminated clonally in one institution. Although molecular data indicated the spread of VRE between two institutions or a potential common source of this alert pathogen, epidemiological investigations did not reveal the possible route by which outbreak strains disseminated. PMID:25003118

Successive Magnetic-Field-Induced Transitions and Colossal Magnetoelectric Effect in Ni 3 TeO 6

DOE PAGES

Kim, Jae Wook; Artyukhin, Sergei; Mun, Eun Deok; ...

2015-09-24

In this paper, we report the discovery of a metamagnetic phase transition in a polar antiferromagnet Ni 3TeO 6 that occurs at 52 T. The new phase transition accompanies a colossal magnetoelectric effect, with a magnetic-field-induced polarization change of 0.3 μC/cm 2, a value that is 4 times larger than for the spin-flop transition at 9 T in the same material, and also comparable to the largest magnetically induced polarization changes observed to date. Via density-functional calculations we construct a full microscopic model that describes the data. We model the spin structures in all fields and clarify the physics behindmore » the 52 T transition. The high-field transition involves a competition between multiple different exchange interactions which drives the polarization change through the exchange-striction mechanism. Finally, the resultant spin structure is rather counterintuitive and complex, thus providing new insights on design principles for materials with strong magnetoelectric coupling.« less

Study of broadband near-infrared emission in Tm3+-Er3+ codoped TeO2-WO3-PbO glasses.

PubMed

Balda, R; Fernández, J; Fernández-Navarro, J M

2009-05-25

In this work, we report the near-infrared emission properties of Tm(3+)-Er(3+) codoped tellurite TeO(2)-WO(3)-PbO glasses under 794 nm excitation. A broad emission from 1350 to 1750 nm corresponding to the Tm(3+) and Er(3+) emissions is observed. The full width at half-maximum of this broadband increases with increasing [Tm]/[Er] concentration ratio up to a value of ~ 160 nm. The energy transfer between Tm(3+) and Er(3+) ions is evidenced by both the temporal behavior of the near-infrared luminescence and the effect of Tm3+ codoping on the visible upconversion of Er(3+) ions.

Tetraethylorthosilicate (TEOS) applied in the surface modification of hydroxyapatite to develop polydimethylsiloxane/hydroxyapatite composites.

PubMed

Bareiro, O; Santos, L A

2014-03-01

Nanometric hydroxyapatite (HAp) particles were modified with 5 or 10 wt.% tetraethylorthosilicate (TEOS) solutions in order to prepare polydimethylsiloxane/hydroxyapatite (PDMS/HAp) composites. The surface modification of the HAp particles was studied by transmission electron spectroscopy (TEM) and by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) equipment. The dispersion state of the modified particles in the PDMS matrix was also assessed by SEM. The composite phase composition was characterized by X-ray diffraction (XRD). The composite thermodynamic parameters of cross-linking were analyzed by differential scanning calorimetry (DSC). TEM micrographs and EDS spectra indicated evidence of silica-coating formation on the surface of modified HAp particles. SEM results showed that the HAp particles formed agglomerates in the PDMS matrix. It was found that the introduction of HAp particles into the PDMS changed the enthalpy of cross-linking and the temperature of the beginning of the cross-linking reaction. EDS results indicated that the surface modification of HAp produced composites showing thermodynamic parameters that were more similar to those of unfilled PDMS. Copyright © 2013 Elsevier B.V. All rights reserved.

Spectroscopy and visible frequency upconversion in Er3+-Yb3+: TeO2-ZnO glass.

PubMed

Mohanty, Deepak Kumar; Rai, Vineet Kumar

2014-01-01

The UV-Vis-NIR absorption studies of the Er(3+)/Er(3+)-Yb(3+) doped/codoped TeO2-ZnO (TZO) glasses fabricated by the melting and quenching method has been performed. The spectroscopic radiative parameters viz. radiative transition probabilities, branching ratios and lifetimes have been determined from the absorption spectrum by using Judd-Ofelt theory. The near infrared (NIR) to visible frequency upconversion (UC) have been monitored by using an excitation of 976 nm wavelength radiation from a CW diode laser. The effect of codoping with Yb(3+) ions on the intensity of the UC emission bands from the Er(3+) ions throughout visible region has been studied. The mechanism responsible for the observed upconversion emissions in the prepared samples have been explained on the basis of excited state absorption and efficient energy transfer processes. Copyright © 2013 Elsevier B.V. All rights reserved.

Upconversion properties of Er3+/Yb3+ co-doped TeO2-TiO2-K2O glasses.

PubMed

Su, Fangning; Deng, Zaide

2006-01-01

The Er3+/Yb3+ co-doped TeO2-TiO2-K2O glasses were prepared by conventional melting procedures, and their upconversion spectra were performed. The dependence of luminescence intensity on the ratio of Yb3+/Er3+ was studied, and the relationship between green upconversion luminescence intensity and Er3+ concentration is discussed in detail. The 546 nm green upconversion luminescence intensity is optimised in the studied glasses either when the Yb3+/Er3+ ratio is 25/1 and Er3+ concentration is 0.1 mol%, or when the Yb3+/Er3+ ratio is 10/1 and Er3+ concentration is 0.15 mol%. These glasses could be one of the potential candidates for LD pumping microchip solid-state lasers.

Optical transitions of Er3+/Yb3+ codoped TeO2-WO3-Bi2O3 glass.

PubMed

Shen, Xiang; Nie, Qiuhua; Xu, Tiefeng; Gao, Yuan

2005-10-01

Optical absorption and emission properties of the Er3+/Yb3+ codoped TeO2-WO3-Bi2O3 (TWB) glass has been investigated. The transition probabilities, excited state lifetimes, and the branching ratios have been predicted for Er3+ based on the Judd-Ofelt theory. The broad 1.5 microm fluorescence was observed under 970 nm excitation, and its full width at half maximum (FWHM) is 77 nm. The emission cross-section is calculated using the McCumber theory, and the peak emission cross-section is 1.03 x 10(-21) cm2 at 1.531 microm. This value is much larger than those of the silicate and phosphate glasses. Efficient green and weak red upconversion luminescence from Er3+ centers in the glass sample was observed at room temperature, and the upconversion excitation processes have been analyzed.

Investigation of radiation shielding properties for MeO-PbCl2-TeO2 (MeO = Bi2O3, MoO3, Sb2O3, WO3, ZnO) glasses

NASA Astrophysics Data System (ADS)

Sayyed, M. I.; Çelikbilek Ersundu, M.; Ersundu, A. E.; Lakshminarayana, G.; Kostka, P.

2018-03-01

In this work, glasses in the MeO-PbCl2-TeO2 (MeO = Bi2O3, MoO3, Sb2O3, WO3, ZnO) system, which show a great potential for optoelectronic applications, were used to evaluate their resistance under high energy ionizing radiations. The basic shielding quantities for determining the penetration of radiation in glass, such as mass attenuation coefficient (μ/ρ), half value layer (HVL), mean free path (MFP) and exposure buildup factor (EBF) values were investigated within the energy range 0.015 MeV ‒ 15 MeV using XCOM program and variation of shielding parameters were compared with different glass systems and ordinary concrete. From the derived results, it was determined that MeO-PbCl2-TeO2 (MeO = Bi2O3, MoO3, Sb2O3, WO3, ZnO) glasses show great potentiality to be used under high energy radiations. Among the studied glass compositions, Bi2O3 and WO3 containing glasses were found to possess superior gamma-ray shielding effectiveness.

TeO$$_2$$ bolometers with Cherenkov signal tagging: towards next-generation neutrinoless double-beta decay experiments

DOE PAGES

Casali, N.; Vignati, Marco; Beeman, J. W.; ...

2015-01-14

CUORE, an array of 988 TeOmore » $$_2$$ bolometers, is about to be one of the most sensitive experiments searching for neutrinoless double-beta decay. Its sensitivity could be further improved by removing the background from α radioactivity. A few years ago it was pointed out that the signal from βs can be tagged by detecting the emitted Cherenkov light, which is not produced by αs. In this paper we confirm this possibility. For the first time we measured the Cherenkov light emitted by a CUORE crystal, and found it to be 100 eV at the Q-value of the decay. To completely reject the α background, we compute that one needs light detectors with baseline noise below 20 eV RMS, a value which is 3–4 times smaller than the average noise of the bolometric light detectors we are using. We point out that an improved light detector technology must be developed to obtain TeO$$_2$$ bolometric experiments able to probe the inverted hierarchy of neutrino masses.« less

Nd3+-doped TeO2-PbF2-AlF3 glasses for laser applications

NASA Astrophysics Data System (ADS)

Lalla, E. A.; Rodríguez-Mendoza, U. R.; Lozano-Gorrín, A. D.; Sanz-Arranz, A.; Rull, F.; Lavín, V.

2016-01-01

A study of the optical properties of Nd3+ ion in TeO2-PbF2-AlF3 glasses has been carried out for different Nd3+ concentrations. Based on the Judd-Ofelt theory, intensity parameters and radiative properties were determined from the absorption spectra. Focusing on the suitability of this host for laser applications, the spectroscopic quality factor χ was obtained with a value of 1.07, a value of the order of other compositions proposed as laser hosts. For the most intense emission corresponding with the 4F3/2 → 4I11/2 transition (1.06 μm), the absorption and emission and have been calculated with values of 1.20 × 10-20 cm2, 2.08 × 10-20 cm2. A positive value for the gain cross-sections has been found for a population inversion factor γ of 0.4 in the spectral range from 1060 to 1110 nm. All these results suggest the potentially use of this system as a laser host.

The study of glass transition temperature in Sb-V2O5-TeO2 glasses at different heating rates

NASA Astrophysics Data System (ADS)

Souri, Dariush

2015-12-01

The glass transition of xSb-(60 - x)V2O5-40TeO2 glasses with 0 < x <15 (in mol%) at different heating rates ( φ = 3-12 K/min) has been studied using differential scanning calorimetry. The glass transition temperature ( T g) and crystallization temperature ( T cr) of these glasses have been determined. The effects of the heating rate and the Sb content on T g have been discussed. It has been observed that the transition region shifts to higher temperatures when the measuring time is reduced. The compositional dependence of T g has been determined and so an empirical equation has been deduced relating the glass transition temperature with the Sb concentration. Also, the value of glass-forming tendency has been studied for the present glasses.

1887 nm lasing in Tm3+-doped TeO2-BaF2-Y2O3 glass microstructured fibers

NASA Astrophysics Data System (ADS)

Wang, Shunbin; Yao, Chuanfei; Jia, Zhixu; Qin, Guanshi; Qin, Weiping

2017-04-01

In this paper, we demonstrate ∼2 μm lasing in Tm3+-doped fluorotellurite microstructured fibers. The Tm3+-doped fibers are based on TeO2-BaF2-Y2O3 glasses and fabricated by using a rod-in-tube method. Under the pump of a 1570 nm Er3+-doped fiber laser, lasing at 1887 nm is obtained in a ∼42.5 cm long Tm3+-doped fiber with a threshold pump power of 94 mW. As the pump power increases to 780 mW, the obtained maximum unsaturated power reaches up to ∼408 mW with a slop efficiency of ∼58.1%. This result indicates that the Tm3+-doped fluorotellurite fibers are promising gain media for ∼2 μm fiber lasers.

Influence of valence state of copper ions on structural and spectroscopic properties of multi-component PbO-Al2O3-TeO2-GeO2-SiO2 glass ceramic system- a possible material for memory switching devices

NASA Astrophysics Data System (ADS)

Tirupataiah, Ch.; Narendrudu, T.; Suresh, S.; Srinivasa Rao, P.; Vinaya Teja, P. M.; Sambasiva Rao, M. V.; Chinna Ram, G.; Krishna Rao, D.

2017-11-01

Multi-component glass ceramics with composition 29PbO-5Al2O3-1TeO2 -10GeO2- (55-x) SiO2 doped with different concentrations of CuO (0 ≤ x ≤ 1.0 mol %) were synthesized by melt quenching technique and subsequent heat treatment. These glass ceramics were characterized by X-ray diffraction, scanning electron microscope, differential thermal analysis, optical absorption, electron paramagnetic resonance, Fourier transform infrared and Raman studies. The absorption spectra of these glass ceramics exhibited a broad absorption band in the range 650-950 nm which is ascribed to 2B1g → 2B2g octahedral transition of Cu2+ ions. A feeble band around 364 nm is also identified in the samples doped with CuO up to 0.6 mol% as being due to charge transfer between the two oxidation states Cu2+ and Cu+ of copper ions. The EPR spectrum recorded at room temperature exhibited a strong resonance signal at g⊥ = 2.072 and a shallow quadruplet at about gǁ = 2.401. FTIR and Raman spectra of the titled samples provide significant information about various structural units viz., silicate, germanate, PbO4, PbO6, AlO6, TeO4 and TeO3 that are present in these ceramic matrix. Analysis of the spectroscopic investigations reveals that with an increase in the concentration of CuO up to 0.6 mol% copper ions do exist in Cu2+ and Cu+ states and they act as modifiers and net work formers respectively. Therefore, glass ceramic sample contains 0.6 mol% of CuO is favorable for memory switching action.

Correction of Visual Perception Based on Neuro-Fuzzy Learning for the Humanoid Robot TEO.

PubMed

Hernandez-Vicen, Juan; Martinez, Santiago; Garcia-Haro, Juan Miguel; Balaguer, Carlos

2018-03-25

New applications related to robotic manipulation or transportation tasks, with or without physical grasping, are continuously being developed. To perform these activities, the robot takes advantage of different kinds of perceptions. One of the key perceptions in robotics is vision. However, some problems related to image processing makes the application of visual information within robot control algorithms difficult. Camera-based systems have inherent errors that affect the quality and reliability of the information obtained. The need of correcting image distortion slows down image parameter computing, which decreases performance of control algorithms. In this paper, a new approach to correcting several sources of visual distortions on images in only one computing step is proposed. The goal of this system/algorithm is the computation of the tilt angle of an object transported by a robot, minimizing image inherent errors and increasing computing speed. After capturing the image, the computer system extracts the angle using a Fuzzy filter that corrects at the same time all possible distortions, obtaining the real angle in only one processing step. This filter has been developed by the means of Neuro-Fuzzy learning techniques, using datasets with information obtained from real experiments. In this way, the computing time has been decreased and the performance of the application has been improved. The resulting algorithm has been tried out experimentally in robot transportation tasks in the humanoid robot TEO (Task Environment Operator) from the University Carlos III of Madrid.

Correction of Visual Perception Based on Neuro-Fuzzy Learning for the Humanoid Robot TEO

PubMed Central

2018-01-01

New applications related to robotic manipulation or transportation tasks, with or without physical grasping, are continuously being developed. To perform these activities, the robot takes advantage of different kinds of perceptions. One of the key perceptions in robotics is vision. However, some problems related to image processing makes the application of visual information within robot control algorithms difficult. Camera-based systems have inherent errors that affect the quality and reliability of the information obtained. The need of correcting image distortion slows down image parameter computing, which decreases performance of control algorithms. In this paper, a new approach to correcting several sources of visual distortions on images in only one computing step is proposed. The goal of this system/algorithm is the computation of the tilt angle of an object transported by a robot, minimizing image inherent errors and increasing computing speed. After capturing the image, the computer system extracts the angle using a Fuzzy filter that corrects at the same time all possible distortions, obtaining the real angle in only one processing step. This filter has been developed by the means of Neuro-Fuzzy learning techniques, using datasets with information obtained from real experiments. In this way, the computing time has been decreased and the performance of the application has been improved. The resulting algorithm has been tried out experimentally in robot transportation tasks in the humanoid robot TEO (Task Environment Operator) from the University Carlos III of Madrid. PMID:29587392

Observation of high-spin mixed oxidation state of cobalt in ceramic Co3TeO6

NASA Astrophysics Data System (ADS)

Singh, Harishchandra; Ghosh, Haranath; Chandrasekhar Rao, T. V.; Sinha, A. K.; Rajput, Parasmani

2014-12-01

We report coexistence of high spin Co3+ and Co2+ in ceramic Co3TeO6 using X-ray Absorption Near Edge Structure (XANES), DC magnetization, and first principles ab-initio calculations. The main absorption line of cobalt Co K-edge XANES spectra, along with a linear combination fit, led us to estimate relative concentration of Co2+ and Co3+as 60:40. The pre edge feature of XANES spectrum shows crystal field splitting of ˜1.26 eV between eg and t2g states, suggesting a mixture of high spin states of both Co2+ and Co3+. Temperature dependent high field DC magnetization measurements reveal dominant antiferromagnetic order with two Neel temperatures (TN1 ˜ 29 K and TN2 ˜ 18 K), consistent with single crystal study. A larger effective magnetic moment is observed in comparison to that reported for single crystal (which contains only Co2+), supports our inference that Co3+ exists in high spin state. Furthermore, we show that both Co2+ and Co3+ being in high spin states constitute a favorable ground state through first principles ab-initio calculations, where Rietveld refined synchrotron X-ray diffraction data are used as input.

Shielding properties of 80TeO2-5TiO2-(15-x) WO3-xAnOm glasses using WinXCom and MCNP5 code

NASA Astrophysics Data System (ADS)

Dong, M. G.; El-Mallawany, R.; Sayyed, M. I.; Tekin, H. O.

2017-12-01

Gamma ray shielding properties of 80TeO2-5TiO2-(15-x) WO3-xAnOm glasses, where AnOm is Nb2O5 = 0.01, 5, Nd2O3 = 3, 5 and Er2O3 = 5 mol% have been achieved. Shielding parameters; mass attenuation coefficients, half value layers, and macroscopic effective removal cross section for fast neutrons have been computed by using WinXCom program and MCNP5 Monte Carlo code. In addition, by using Geometric Progression method (G-P), exposure buildup factor values were also calculated. Variations of shielding parameters are discussed for the effect of REO addition into the glasses and photon energy.

Spectroscopic and energy transfer studies of Er3+ ions in B2O3-TeO2-MgO-ZnO glasses

NASA Astrophysics Data System (ADS)

Vijayakumar, M.; Arunkumar, S.; Maheshvaran, K.; Marimuthu, K.

2016-05-01

Composition dependent spectroscopic behavior of Er3+ doped telluroborate glasses were prepared and the energy transfer mechanism in Er3+ ions were investigated for 1.532 µm amplification. The emission cross-section and gain coefficient for 4I13/2→4I15/2 level of Er3+ ions have been analysed through the Judd-Ofelt and McCumber theory. The excited state decay curves were measured and the effect of TeO2 on the lifetime for 4I13/2→4I15/2 level of Er3+ ions has been associated with the various energy transfer mechanism. Further the interaction between Er3+ and OH- were investigated and it was confirmed that the OH free radicals in the prepared glasses are dominant quenching center through the non-radiative relaxation that causes the quenching of 1.532 µm amplification. The non-radiative rate through the OH content were calculated and compared with the reported Er3+ doped glasses.

Emission analysis of RE3+ (RE = Sm, Dy):B2O3-TeO2-Li2O-AlF3 glasses.

PubMed

Raju, C Nageswara; Sailaja, S; Kumari, S Pavan; Dhoble, S J; Kumar, V Ramesh; Ramanaiah, M V; Reddy, B Sudhakar

2013-01-01

This article reports on the optical properties of 0.5% mol of Sm(3+), Dy(3+) ion-doped B2O3-TeO2-Li2O-AlF3 (LiAlFBT) glasses. The glass samples were characterized by optical absorption and emission spectra. Judd-Ofelt theory was applied to analyze the optical absorption spectra and calculate the intensity parameters and radiative properties of the emission transitions. The emission spectra of Sm(3+) and Dy(3+):LiAlFBT glasses showed a bright reddish-orange emission at 598 nm ((4)G5/2 → (6)H7/2) and an intense yellow emission at 574 nm ((4)F9/2 → (6)H13/2), respectively. Full width at half maximum (FWHM), stimulated emission cross section, gain bandwidth and optical gain values were also calculated to extend the applications of the Sm(3+) and Dy(3+):LiAlFBT glasses. Copyright © 2012 John Wiley & Sons, Ltd.

Intense upconversion luminescence and effect of local environment for Tm3+/Yb3+ co-doped novel TeO2-BiCl3 glass system.

PubMed

Wang, Guonian; Dai, Shixun; Zhang, Junjie; Wen, Lei; Yang, Jianhu; Jiang, Zhonghong

2006-05-15

We present the results of a study that uses theoretical and experimental methods to investigate the characteristics of the upconversion luminescence of Tm3+/Yb3+ codoped TeO2-BiCl3 glass system as a function of the BiCl3 fraction. These glasses are potentially important in the design of upconversion fiber lasers. Effect of local environment around Tm3+ on upconversion fluorescence intensity was analyzed by theoretical calculations. The structure and spectroscopic properties were investigated in the experiments by measuring the Raman spectra, IR transmission spectra, and absorption and fluorescence intensities at room temperature. The results indicate that blue luminescence quantum efficiency increases with increasing BiCl3 content from 10 to 60 mol%, which were interpreted by the increase of asymmetry of glass structure, decrease of phonon energy and removing of OH- groups.

Spectroscopic properties of the 1.4 microm emission of Tm3+ ions in TeO2-WO3-PbO glasses.

PubMed

Balda, R; Lacha, L M; Fernández, J; Arriandiaga, M A; Fernández-Navarro, J M; Muñoz-Martin, D

2008-08-04

In this work, we report the spectroscopic properties of the infrared 3H4-->3F4 emission of Tm3+ ions in two different compositions of glasses based on TeO2, WO3, and PbO for three Tm2O3 concentrations (0.1,0.5, and 1 wt%). Judd-Ofelt intensity parameters have been determined and used to calculate the radiative transition probabilities and radiative lifetimes. The infrared emission at around 1490 nm corresponding to the 3H4-->F4 transition has two noticeable features if compared to fluoride glasses used for S-band amplifiers. On one hand, it is broader by nearly 30 nm, and on the other, the stimulated emission cross section is twice the value for fluoride glasses. Both the relative intensity ratio of the 1490 nm emission to 1820 nm and the measured lifetime of the 3H4 level decrease as concentration increases, due to the existence of energy transfer via cross-relaxation among Tm3+ ions. The analysis of the decays from the 3H4 level with increasing concentration indicates the presence of a dipole-dipole quenching process assisted by energy migration.

Industrial production of 131I by neutron irradiation and melting of sintered TeO2

NASA Astrophysics Data System (ADS)

Alanis, Jose; Navarrete, Manuel

2001-07-01

Optimal conditions of temperature and reaction rate have been settled to produce high purity TeO2 by the chemical reaction between Te and HNO3. Also, heating and time conditions for sintering this product have been found, in order to create cavities in the crystal inside, where a gaseous element such as iodine can be adsorbed with minimal leaking. In this way it is fabricated a suitable target to be irradiated with thermal neutrons for obtaining 131Te(t1/2=24.8 m) and 131mTe(t1/2=30 h) by (n, γ) nuclear reactions. Irradiation time has been chosen to get 131Te saturation activity (ti=150 m) because much longer irradiation times do not increase significantly total activity. Since parents 131Te and 131mTe have shorter half life than daughter 131I(t1/2=8.05 d) optimal cooling time must permit daughter activity to grow up till a maximum (tc=4d). Then, sintered cylinder shaped radioactive sample is manipulated in a hot cell, transported and put on a quartz tray, keeping Health Physics regulations. The quartz tray is inside a small electric oven enclosed in an airtight box with negative pressure (water 0.5 cm). There, it is gradually heated till melting point (733 °C). From 400 °C on, vapors are pumped out and bubbled in two solutions: one is 0.1 M NaOH, which retains nearly 99.9% of pumped 131I. Other is 0.02 M Na2CO3 (60%) plus 0.0025 M NaHCO3 (40%), which retains the remaining sample residue. Air filtering is accomplished by activated carbon and alumina filters in the inflow, glass wool fiber before bubbling, and activated carbon again in the outflow.

Structural, morphological and optical investigations on electron-beam irradiated PbF2-TeO2-B2O3-Eu2O3 glasses

NASA Astrophysics Data System (ADS)

Wagh, Akshatha; Petwal, Vikash; Dwivedi, Jishnu; Upadhyaya, V.; Raviprakash, Y.; Kamath, Sudha D.

2016-09-01

Combined structural, optical and morphological studies were carried out on Eu2O3 doped PbF2-TeO2-B2O3 glass samples, before and after being subjected to electron beam of energy 7.5 MeV. XRD confirmed the amorphous nature of the glasses even after 150 kGy electron beam irradiation. Densities of the irradiated samples showed slightly greater values when compared to their respective values before irradiation, which proved the increase in the compaction of the network. The intensities of the three prominent bands; B-O-B linkages, BO4 units and BO3 units of FT-IR spectra, of the titled glasses, showed slight decrease after electron beam irradiation. The decrement in the values of energy band gap and shift in cut-off wavelength towards red edge, proved the formation of color centers in the glass network after irradiation. The change in Hunter L values, through color measurement was a proof for the Farbe/color/absorption centers created in the glass sites after irradiation.

Structure of zinc and niobium tellurite glasses by neutron and x-ray diffraction

NASA Astrophysics Data System (ADS)

Hoppe, U.; Yousef, E.; Rüssel, C.; Neuefeind, J.; Hannon, A. C.

2004-03-01

Neutron and x-ray diffraction experiments of high resolving power with neutrons from a spallation source and high-energy photons from a synchrotron have been performed on compositional series of binary Zn, Nb and on mixed Zn/Nb tellurite glasses. The Te-O, Zn-O and Nb-O coordination numbers are determined by Gaussian fitting of the first-neighbour peaks in the neutron and x-ray data simultaneously. The transition of TeO4 to TeO3 units with increasing fraction of a second component is indicated by decreasing total Te-O coordination numbers. This transition appears different for glasses with ZnO or Nb2O5 additions. Details of the Te-O peaks suggest there are two species of Te-O bonds with lengths of {\\sim }0.19 and {\\sim }0.21 nm. The change of their fractions shows excellent agreement with the existence of TeO4 trigonal bipyramids and TeO3 trigonal pyramids. All oxygen atoms from ZnO and Nb2O5 are used for rupture of Te-O-Te bridges, which is accompanied with a change of nearly all participating TeO4 to TeO3 groups. The tendency for a {\\mathrm {TeO}}_{4} \\to {\\mathrm {TeO}}_{3} change decreases for glasses of higher second component content which is accompanied by the occurrence of TeO4 groups with non-bridging oxygens. The Nb tellurite glasses show transition to network-forming behaviour with the formation of Nb-O-Nb bridges. The fractions of TeO3 units of ternary Zn/Nb tellurite glasses agree with an additivity behaviour of the modifying effects of ZnO and Nb2O5 additions. Some of these results have already been presented in thesis work: Yousef E 2003 A study of some physical properties of tellurite glass (Al-Azhar University, Assiut Egypt).

Effect of antimony on the optical and physical properties of Sb-V2O5-TeO2 glasses

NASA Astrophysics Data System (ADS)

Souri, Dariush; Mohammadi, Mousa; Zaliani, Hamideh

2014-11-01

Ternary glass systems of the form xSb-(60- x) V2O5-40TeO2 (Sx glasses) with 0 ≤ x ≤ 15 (in mol. %) have been prepared by using the normal melt quenching technique. The optical absorption spectra of these glasses have been recorded within wavelength range of 190 — 1100 nm. The absorption spectrum fitting method was employed to obtain the energy band gap. In this method, only the measurement of absorbance spectrum of the glass is needed. The position of the absorption edge and therefore the optical band gap values were found to be depend on glass composition. Results show that the optical band gap is in the range 1.57 — 2.14 eV. For each sample, the width of the band tail was determined. The densities of present glasses were measured and the molar volumes were calculated. Also, some thermal properties such as glass transition temperature ( T g) and crystallization temperature (TCr) were obtained by using differential scanning calorimetry (DSC) technique, and from which the glass thermal stability S and glass forming tendency K gl were calculated. Results show that these glasses (specially for x ≥ 10 mol. %) have good stability and therefore good resistance against thermal shocks for technological applications in fiber devices. Also, T g values indicate the rigidity and packing of the samples increase with increasing the Sb concentration as a network modifier. [Figure not available: see fulltext.

Rhodococcus aetherivorans BCP1 as cell factory for the production of intracellular tellurium nanorods under aerobic conditions.

PubMed

Presentato, Alessandro; Piacenza, Elena; Anikovskiy, Max; Cappelletti, Martina; Zannoni, Davide; Turner, Raymond J

2016-12-15

Tellurite (TeO 3 2- ) is recognized as a toxic oxyanion to living organisms. However, mainly anaerobic or facultative-anaerobic microorganisms are able to tolerate and convert TeO 3 2- into the less toxic and available form of elemental Tellurium (Te 0 ), producing Te-deposits or Te-nanostructures. The use of TeO 3 2- -reducing bacteria can lead to the decontamination of polluted environments and the development of "green-synthesis" methods for the production of nanomaterials. In this study, the tolerance and the consumption of TeO 3 2- have been investigated, along with the production and characterization of Te-nanorods by Rhodococcus aetherivorans BCP1 grown under aerobic conditions. Aerobically grown BCP1 cells showed high tolerance towards TeO 3 2- with a minimal inhibitory concentration (MIC) of 2800 μg/mL (11.2 mM). TeO 3 2- consumption has been evaluated exposing the BCP1 strain to either 100 or 500 μg/mL of K 2 TeO 3 (unconditioned growth) or after re-inoculation in fresh medium with new addition of K 2 TeO 3 (conditioned growth). A complete consumption of TeO 3 2- at 100 μg/mL was observed under both growth conditions, although conditioned cells showed higher consumption rate. Unconditioned and conditioned BCP1 cells partially consumed TeO 3 2- at 500 μg/mL. However, a greater TeO 3 2- consumption was observed with conditioned cells. The production of intracellular, not aggregated and rod-shaped Te-nanostructures (TeNRs) was observed as a consequence of TeO 3 2- reduction. Extracted TeNRs appear to be embedded in an organic surrounding material, as suggested by the chemical-physical characterization. Moreover, we observed longer TeNRs depending on either the concentration of precursor (100 or 500 μg/mL of K 2 TeO 3 ) or the growth conditions (unconditioned or conditioned grown cells). Rhodococcus aetherivorans BCP1 is able to tolerate high concentrations of TeO 3 2- during its growth under aerobic conditions. Moreover, compared to unconditioned

Spectral properties and anti-Stokes luminescence of TeO2-BaF2:Ho3+, Ho3+/Yb3+ ceramics and glass excited by 1.9-μm radiation of a Tm:LiYF4 laser

NASA Astrophysics Data System (ADS)

Savikin, A. P.; Egorov, A. S.; Budruev, A. V.; Perunin, I. Yu.; Krasheninnikova, O. V.; Grishin, I. A.

2017-07-01

We demonstrate the up-conversion of Tm:LiYF4 infrared (IR) laser radiation with 1908-nm wavelength into visible light with a spectral maximum at 650 nm by ceramics with a composition of (100 - x)TeO2- xBaF2 - 1 wt % HoF3- yYbF3, where x = 20, 30, or 40 mol % and y = 0 or 0.5 wt %. The samples of 60TeO2-40BaF2 - 1 wt % HoF3 - 0.5 wt % YbF3 exhibited anti-Stokes luminescence at a threshold radiation power density of 1.0-1.5 W cm-2.

Investigation of thermal stability and spectroscopic properties in Er3+/Yb3+-codoped TeO2-Li2O-B2O3-GeO2 glasses.

PubMed

Nie, Qiu-Hua; Gao, Yuan; Xu, Tie-Feng; Shen, Xiang

2005-06-01

The new Er3+/Yb3+ co-doped 70TeO2-5Li2O-(25-x)B2O3-xGeO2 (x = 0, 5, 10, 15 fand 20 mol.%) glasses were prepared. The thermal stability, absorption spectra, emission spectra and lifetime of the 4I(13/2) level of Er3+ ions were measured and studied. The FT-IR spectra were carried out in order to investigate the structure of local arrangements in glasses. It is found that the thermal stability, absorption cross-section of Yb3+, emission intensity and lifetime of the 4I(13/2) level of Er3+ increase with increasing GeO2 content in the glass composition, while the fluorescence width at half maximum (FWHM) at 1.5 um of Er3+ is about 70 nm. The obtained data suggest that this system glass can be used as a candidate host material for potential broadband optical amplifiers.

Preparation and optical properties of TeO2-BaO-ZnO-ZnF2 fluoro-tellurite glass for mid-infrared fiber Raman laser applications

NASA Astrophysics Data System (ADS)

Li, Jie; Xiao, Xusheng; Gu, Shaoxuan; Xu, Yantao; Zhou, Zhiguang; Guo, Haitao

2017-04-01

A serial of novel fluoro-tellurite glasses with compositions of 60TeO2-20BaO-(20-x)ZnO-xZnF2 (x = 0, 2, 4, 5 and 6 mol%) were prepared. The compositional dependences of glass structural evaluation, Raman gain coefficient, UV-Vis transmission spectrum, IR transmission spectrum, linear refractive index and third-order nonlinearity were analyzed. The results showed that the addition of 6 mol% ZnF2 can further improve the Raman gain coefficient to as well as 52 × 10-11 cm/W and effectively decrease around 73% and 57% absorption coefficients respectively caused by free Osbnd H groups (@3.3 μm) and hydrogen-bonded Osbnd H groups (@4.5 μm) in glass. Addition of ZnF2 does not change the UV-Vis absorption edge, optical band gap energy and infrared region cut-off edge almost, while the linear refraction index and ultrafast third-nonlinearity show unmonotonic changes. These novel fluoro-tellurite glasses may be suitable candidates for using in mid-infrared Raman fiber laser and/or amplifier.

Dispersion of the Vancomycin Resistance Genes vanA and vanC of Enterococcus Isolated from Nile Tilapia on Retail Sale: A Public Health Hazard.

PubMed

Osman, Kamelia M; Ali, Mohamed N; Radwan, Ismail; ElHofy, Fatma; Abed, Ahmed H; Orabi, Ahmed; Fawzy, Nehal M

2016-01-01

Although normally regarded harmless commensals, enterococci may cause a range of different infections in humans, including urinary tract infections, sepsis, and endocarditis. The acquisition of vancomycin resistance by enterococci (VRE) has seriously affected the treatment and infection control of these organisms. VRE are frequently resistant to all antibiotics that are effective treatment for vancomycin-susceptible enterococci, which leaves clinicians treating VRE infections with limited therapeutic options. With VRE emerging as a global threat to public health, we aimed to isolate, identify enterococci species from tilapia and their resistance to van-mediated glycopeptide (vanA and vanC) as well as the presence of enterococcal surface protein (esp) using conventional and molecular methods. The cultural, biochemical (Vitek 2 system) and polymerase chain reaction results revealed eight Enterococcus isolates from the 80 fish samples (10%) to be further identified as E. faecalis (6/8, 75%) and E gallinarum (2/8, 25%). Intraperitoneal injection of healthy Nile tilapia with the eight Enterococcus isolates caused significant morbidity (70%) within 3 days and 100% mortality at 6 days post-injection with general signs of septicemia. All of the eight Enterococcus isolates were found to be resistant to tetracycline. The 6/6 E. faecalis isolates were susceptible for penicillin, nitrofurantoin, gentamicin, and streptomycin. On the other hand 5/6 were susceptible for ampicillin, vancomycin, chloramphenicol, and ciprofloxacin. The two isolates of E. gallinarum were sensitive to rifampicin and ciprofloxacin and resistant to vancomycin, chloramphenicol, and erythromycin. Molecular characterization proved that they all presented the prototypic vanC element. On the whole, one of the two vancomycin resistance gene was present in 3/8 of the enterococci isolates, while the esp virulence gene was present in 1/8 of the enterococci isolates. The results in this study emphasize the

Phase equilibria in the Bi 2TeO 5Bi 2SeO 5 system and a high temperature neutron powder diffraction study of Bi 2SeO 5

NASA Astrophysics Data System (ADS)

Dityatyev, Oleg A.; Smidt, Peer; Stefanovich, Sergey Yu; Lightfoot, Philip; Dolgikh, Valery A.; Opperman, Heinrich

2004-09-01

Phase equilibria in the Bi 2TeO 5Bi 2SeO 5 system were studied by X-ray, DTA and second harmonic generation (SHG). The samples were synthesized by solid state reactions of the Bi, Te and Se oxides. The phase diagram is interpreted as a quasibinary peritectic one with wide ranges of solid solutions on the basis of both compounds. The SHG study showed Bi 2SeO 5 to undergo a phase transition at about 250 °C. Neutron diffraction (25-650 °C) showed no major changes in the structure of Bi 2SeO 5 at high temperatures. However, the analysis of the oxygen atom thermal factors and site occupancies suggested that the mechanism of the phase transformation is an order-disorder transition involving reorientation of the SeO 3 group.

Dehydration of an ethanol/water azeotrope by novel organic-inorganic hybrid membranes based on quaternized chitosan and tetraethoxysilane.

PubMed

Uragami, Tadashi; Katayama, Takuya; Miyata, Takashi; Tamura, Hiroshi; Shiraiwa, Tadashi; Higuchi, Akon

2004-01-01

To control swelling of quaternized chitosan (q-Chito) membranes, mixtures of q-Chito as an organic component and tetraethoxysilane (TEOS) as an inorganic component were prepared using the sol-gel reaction, and novel q-Chito/TEOS hybrid membranes were formed. In the separation of an ethanol/water azeotrope by pervaporation, the effect of TEOS content on the water/ethanol selectivity of q-Chito/TEOS hybrid membranes was investigated. Hybrid membranes containing up to 45 mol % TEOS exhibited higher water/ethanol selectivity than the q-Chito membrane. This resulted from depressed swelling of the membranes by formation of a cross-linked structure. However, introduction of excess TEOS led to greater swelling of the hybrid membranes. Therefore, the water/ethanol selectivity of the hybrid membranes containing more than 45 mol % TEOS was lower than that of the q-Chito membrane. The relationship between the structure of q-Chito/TEOS hybrid membranes and their permeation and separation characteristics during pervaporation of an ethanol/water azeotrope is discussed in detail.

Vancomycin resistant Enterococcus spp. from crows and their environment in metropolitan Washington State, USA: Is there a correlation between VRE positive crows and the environment?

PubMed

Roberts, Marilyn C; No, David B; Marzluff, John M; Delap, Jack H; Turner, Robert

2016-10-15

Vancomycin-resistant enterococci [VRE] have been isolated from municipal, hospital and agricultural wastewater, recreational beaches, wild animals, birds and food animals around the world. In this study, American crows (Corvus brachyrhynchos) from sewage treatment plants (WWTP), dairy farms, and a large roost in a restored wetland with corresponding environmental samples were cultured for VRE. A total of 245 samples [156 crows, 89 environmental] were collected and screened for acquired vanA, vanB and/or intrinsic vanC1 genes. Samples were enriched overnight in BHI supplemented with 20μg/mL aztreonam, 4μg/mL vancomycin and plated on m-Enterococcus agar media supplemented with 6μg/mL vancomycin. Selected colonies were grown on BHI media supplemented with 18μg/mL vancomycin. Of these, 24.5% of the crow and 55% the environmental/cow samples were VRE positive as defined by Enterococcus spp. able to grow on media supplemented with 18μg/mL vancomycin. A total of 122 VRE isolates, 43 crow and 79 environmental isolates were screened, identified to species level using 16S sequencing and further characterized. Four vanA E. faecium and multiple vanC1 E. gallinarum were identified from crows isolated from three sites. E. faecium vanA and E. gallinarum vanC1 along with other Enterococcus spp. carrying vanA, vanB, vanC1 were isolated from three environments. All enterococci were multidrug resistant. Crows were more likely to carry vanA E. faecium than either the cow feces or wetland waters/soils. Comparing E. gallinarum vanC1 from crows and their environment would be useful in determining whether crows share VRE strains with their environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Raman spectrum, quantum mechanical calculations and vibrational assignments of (95% alpha-TeO2/5% Sm2O3) glass.

PubMed

Shaltout, I; Mohamed, Tarek A

2007-06-01

Chozen system of tellurite glasses doped with rare earth oxides (95% alpha-TeO(2)+5% Sm2O3) was prepared by melt quenching. Consequently, the Raman spectrum (150-1250 cm(-1)) of the modified tellurite have been recorded. As a continuation to our normal coordinate analysis, force constants and quantum mechanical (QM) calculations for tbp TeO4(4-) (triagonal bipyramid, C(2v)) and TeO(3+1); Te2O7(6-) (bridged tetrahedral), we have carried out ab initio frequency calculations for tpy TeO3(2-) (triagonal pyramidal, C(3v) and C(s)) and tp TeO3(2-) (triagonal planar, D(3h)) ions. The quantum mechanical calculations at the levels of RHF, B3LYP and MP2 allow confident vibrational assignments and structural identification in the binary oxide glass (95% alpha-TeO2 +5% Sm2O3). The dominant three-dimensional network structures in the modified glass are triagonal pyramidal TeO3 with minor features of short range distorted tbp TeO4 and bridged tetrahedral unit of TeO(3+1), leading to a structure of infinite chain. Therefore, alpha-TeO2/Sm2O3 (95/5%) glass experience structural changes from TeO4 (tbp); Te2O7 (TeO(3+1))-->TeO3 (tpy).

Optical spectroscopy of Sm(3+) doped Na2O-ZnO-La2O3-TeO2 glasses.

PubMed

Sobczyk, Marcin

2015-10-05

Telluride glasses with the composition xSm2O3-(7-x)La2O3-3Na2O-25ZnO-65TeO2 (where x=0.1, 1, 2, 5 and 7 mol%) were obtained by the melt quenching technique. Electronic absorption and fluorescence spectra as well as fluorescence dynamics of the Sm(3+)-doped title glasses are presented and analysed in detail. A Judd-Ofelt intensity analysis of the absorption spectrum at 300 K has been applied for determination of Ωλ parameters (Ω2=3.10, Ω4=3.80, Ω6=1.61×10(-20) cm(2)) which in turn have been used for calculations of the radiative transition probabilities (AT), the natural (radiative) lifetimes (τR) of the (4)G5/2 level of Sm(3+), the fluorescence branching ratios (β) and the emission cross-sections (σem). The τR value of the (4)G5/2 level amount to 1546 μs and is slightly higher than the measured decay time of 1306 μs. With the increasing of Sm2O3 concentration from 0.1 to 7.0 mol% the experimental lifetime of the fluorescent level decreases from 1306 to 41 μs. An analysis of the non-radiative decay was based on the cross-relaxation mechanisms. The optical achieved results indicate that the investigated glasses are potentially applicable as an orange and/or red laser host. Copyright © 2015 Elsevier B.V. All rights reserved.

Structural characterization of ZnCl2 modified tellurite based glasses

NASA Astrophysics Data System (ADS)

Dhankhar, Sunil; Kundu, R. S.; Punia, R.; Sunita, Parmar, R.; Sanjay, Kishore, N.

2016-05-01

Glass composition 70 TeO2-(30-x) BaO - x ZnCl2; x = 5, 10, 15, 20 and 25 have been prepared by rapid melt quenching technique under controlled atmospheric conditions. Amorphous nature of the samples was confirmed by x-ray diffractogram. The glass transition temperature (Tg) has been determined using differential scanning calorimetry (DSC) and its value is observed to decrease with increase in ZnCl2 content. The peaks in the Raman and FTIR spectra have been estimated by deconvolutation of the spectra and each of deconvoluted spectra exhibits several peaks. IR and Raman spectra of the present glass system indicate that TeO2 exists as TeO3 trigonal pyramidal (tp), TeO4 trigonal bipyramidal (tbp) and TeO6 polyhedra structural units. With increase in zinc halide content, transformation of some of TeO4 structural units into TeO3 structural units is observed Increase in TeO3 structural units shows that non-bridging oxygen contribution increases which confirms the decrease in glass transition temperature.

Characterization of p-Type CdTe Electrodes in Acetonitrile/Electrolyte Solutions. Nearly Ideal Behavior from Reductive Surface Pretreatments.

DTIC Science & Technology

1983-06-30

using Ag conductive palnt and the entire assembly was mounted in glass tubing with ordinary epoxy leaving only the front crystal face, ...energy set, several eV higher than either Te2- or Teo (as measured for sputtered CdTe and Te, respectively) is assigned to TeO2 , the lowest stable...binding energy reported for TeO2 (575.9 eV). 33 The lower binding energy set of bands, lying midway between Teo and Te2 - , results from both Teo and

Time Integrating Optical Signal Processing

DTIC Science & Technology

1981-07-01

advantage of greatly reducing the bandwidth requirement for the memory feeding the second cell. For a system composed of a PbMoO 4 and a ( TeO2 )s Bragg cell...bounds. ( TeO2 )L and ( TeO2 )s represent, respectively, the long- / , / itudinal and slow shear / modes of TeO2 . ’a , / / /a ’o [ / / / / was assumed here...could be implemented with a 25mm TeO2 device operated in the longitudinal mode in a hybrid system. A purely time-integrating system would require about

[Implementation of vanA and vanB genes by PCR technique research interest in system (Xpert vanA/vanB CepheidR) closed in a laboratory of microbiology in managing an outbreak to Enterococcus faecium resistant glycopeptide (EfRG)].

PubMed

Dekeyser, S; Beclin, E; Descamps, D

2011-04-01

The closed system PCR for the rapid detection of vanA and vanB genes (Xpert vanA/vanB Cepheid(®)) was evaluated in our laboratory, to improve the rapidity of the response and thus the management of patients and isolation measures during two GRE outbreaks. From March to December2009, 565 samples were analysed by PCR associated to bacterial culture initially for all samples for 2months (n = 75), and thereafter for PCR-positive samples only. In this study, sensitivity and negative predictive values of the PCR were 100%. Specificity was evaluated in the presence and absence of outbreak: 69.3 and 76.8% respectively. The variability of false positive rates between units were lower in nonepidemic than during epidemic phase. The global false positive rate was 23.9%. This easy-to-use technology provides rapid results… four samples are tested in 1h versus 72h for culture. Despite its reagent cost, it represents an important hospital diagnostic tool: improvement of the management of cohorting areas and patient transfer between units, adaptation of isolation measures and treatments. However, culture remains necessary to confirm any positive result obtained by PCR and for epidemiological surveillance. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

Hydrophobicity of silica thin films: The deconvolution and interpretation by Fourier-transform infrared spectroscopy

NASA Astrophysics Data System (ADS)

Saputra, Riza Eka; Astuti, Yayuk; Darmawan, Adi

2018-06-01

This work investigated the synthesis of dimethoxydimethylsilane:tetraethoxysilane (DMDMS:TEOS) silica thin films as well as the effect of DMDMS:TEOS molar ratios and calcination temperature on hydrophobic properties of silica thin films and its correlation with the FTIR spectra behaviour. The silica thin films were synthesized by sol-gel method using combination of DMDMS and TEOS as silica precursors, ethanol as solvent and ammonia as catalyst, with DMDMS and TEOS molar ratio of 10:90, 25:75, 50:50, 75:25 and 90:10. The results showed that DMDMS:TEOS molar ratio had significant impact on the hydrophobic properties of silica thin films coated on a glass surface. Furthermore, the correlation between water contact angle (WCA) and DMDMS:TEOS molar ratio was found to be in a parabolic shape. Concurrently, the maximum apex of the parabola obtained was observed on the DMDMS:TEOS molar ratio of 50:50 for all calcination temperature. It was clearly observed that the silica xerogel exhibiting notable change in relative peak intensities showed FTIR peak splitting of υasymmetric Si-O-Si. To uncover what happened at the FTIR peak, the deconvolution was conducted in Gaussian approach. It was established that the changes in the Gaussian peak component were related to DMDMS:TEOS molar ratios and the calcination temperature that allowed us to tailor the DMDMS:TEOS silica polymer structure model based on the peak intensity ratios. With the increase of DMDMS:TEOS molar ratio, the ratio of (cyclic Si-O-Si)/(linear Si-O-Si) decreased, whilst the ratio of (C-H)/(linear Si-O-Si) increased. Both ratios intersected at DMDMS:TEOS molar ratio of 50:50 with contribution factor ratio of 1:16 and 1:50 for silica xerogel calcined at 300 °C and 500 °C respectively. The importance of this research is the DMDMS:TEOS molar ratio plays an important role in determining the hydrophobic properties of thin films.

Laser-diode-excited blue upconversion in Tm3+/Yb3+ -codoped TeO2-Ga2O3-R2O (R=Li, Na, K) glasses.

PubMed

Zhao, Chun; Zhang, Qinyuan; Yang, Gangfeng; Jiang, Zhonghong

2008-01-01

This paper reports on intense blue upconversion in Tm(3+)/Yb(3+) codoped TeO(2)-Ga(2)O(3)-R(2)O(R=Li, Na, K) glasses upon excitation with commercial available laser diode (LD). Effects of alkali ions on the Raman spectra, thermal stability and spectroscopic properties of the tellurite-gallium glasses have also been investigated. Energy transfer and the involved upconversion mechanisms have been discussed. Intense blue upconversion emission centered at 476 nm along with a weak red emission at 650 nm has been observed upon excitation of 977 nm LD, assigned to the transitions of 1G4-->3H6, and 1G4-->3H4 and/or 3F(2,3)-->3H6 of Tm(3+), respectively. The blue upconversion intensity has a cubelike dependence on incident pump laser power, indicating a three-photon process. However, a quadratic dependence of the 476 nm upconversion intensity on the incident pump laser power has been observed when samples under excitation of 808 nm LD due to a two-photon absorption process. Enhanced upconversion luminescence have been observed with replacing K(+) for Na(+) and Li(+).

Hybrid Coatings Enriched with Tetraethoxysilane for Corrosion Mitigation of Hot-Dip Galvanized Steel in Chloride Contaminated Simulated Concrete Pore Solutions

PubMed Central

Figueira, Rita B.; Callone, Emanuela; Silva, Carlos J. R.; Pereira, Elsa V.; Dirè, Sandra

2017-01-01

Hybrid sol-gel coatings, named U(X):TEOS, based on ureasilicate matrices (U(X)) enriched with tetraethoxysilane (TEOS), were synthesized. The influence of TEOS addition was studied on both the structure of the hybrid sol-gel films as well as on the electrochemical properties. The effect of TEOS on the structure of the hybrid sol-gel films was investigated by solid state Nuclear Magnetic Resonance. The dielectric properties of the different materials were investigated by electrochemical impedance spectroscopy. The corrosion behavior of the hybrid coatings on HDGS was studied in chloride-contaminated simulated concrete pore solutions (SCPS) by polarization resistance measurements. The roughness of the HDGS coated with hybrids was also characterized by atomic force microscopy. The structural characterization of the hybrid materials proved the effective reaction between Jeffamine® and 3-isocyanate propyltriethoxysilane (ICPTES) and indicated that the addition of TEOS does not seem to affect the organic structure or to increase the degree of condensation of the hybrid materials. Despite the apparent lack of influence on the hybrids architecture, the polarization resistance measurements confirmed that TEOS addition improves the corrosion resistance of the hybrid coatings (U(X):TEOS) in chloride-contaminated SCPS when compared to samples prepared without any TEOS (U(X)). This behavior could be related to the decrease in roughness of the hybrid coatings (due TEOS addition) and to the different metal coating interaction resulting from the increase of the inorganic component in the hybrid matrix. PMID:28772667

Modification of Montmorillonite with Cetyl Trimethylammonium Bromide and Tetra Ethyl Ortho Silicate

NASA Astrophysics Data System (ADS)

Widjonarko, D. M.; Mayasari, O. D.; Wahyuningsih, S.; Nugrahaningtyas, K. D.

2018-03-01

Modification of montmorillonite (MMt) with cetyltrimethylammonium bromide (CTAB) and tetraethyl ortosilicate (TEOS) has been done. The aim of the research is to study the effect of TEOS and CTAB into MMt. This research is a preliminary step to invent material that can be modified with other functional materials. The study was conducted by recting TEOS with MMt and varying CTAB concentration on MMt previously modified with TEOS. The TEOS concentration was 4.72 M while CTAB concentration was 0.25; 0.5; 2; 3.5; and 5 mmol/g in MMt which has been reacted with TEOS. Material characterization was done by X-Ray Diffraction (XRD), Fourrier Transform Infra-Red Spectrophotometer (FTIR) and Scanning Electron Microscope (SEM). Cation exchange capacity (CEC) of materials was analyzed by titration method. The results show that TEOS and CTAB successfully modified. TEOS adsorbed onto MMt. It was identified from increased basal spacing, specific group and also by its elemental composition, originally having basal spacing 16 Å. After modification with CTAB, basal spacing increased to 28.45 Å or 77.64%. This indicates that CTAB is intercalated within the MMt layers. The CEC of new material is 0.93 meq/g, increase from 0.83 meq/g.

Polarizability, optical basicity and optical properties of SiO2B2O3Bi2O3TeO2 glass system

NASA Astrophysics Data System (ADS)

Kashif, I.; Ratep, A.; Adel, Gh.

2018-07-01

Glasses having a composition xSiO2 xB2O3 (95-2 x) Bi2O35TeO2 where x = (5, 10, 15, 20, 25) prepared by the melt-quenching technique. Thermal stability, density, optical transmittance, and the refractive index of these glasses investigated. Glass samples were transparent in the visible to near-infrared (NIR) region and had a high refractive index. A number of glass samples have high glass-forming ability. This indicates that the quarterly glasses are suitable for optical applications in the visible to the NIR region. Bi2O3 substituted by B2O3 and SiO2 on optical properties discussed. It suggested that the substitution of Bi2O3 increased the density, molar volume, the molar polarizability, optical basicity and refractive index in addition to, the oxygen packing density, the optical energy gap, and metallization decrease. These results are helpful for designing new optical glasses controlled to have a higher refractive index. All studied glass presented high nonlinearities, and the addition of network modifiers made a little contribution. Results clarified the bandgap energy reduction, which associated with the growth within the non-bridging oxygen content with the addition of the network modifier. An increase in the refractive index nonlinearity explained by the optical basicity and the high electronic polarizability of the modifier ions.

Acousto-Optic Beam Steering Study

DTIC Science & Technology

1994-08-01

S25 2.500000 PRIVATE CATALOG PWL 830.00 ’THIN’ 1.010000 PWL 830.00 ’ TEO2 ’ 2.200000 REFRACTIVE INDICES GLASS CODE 830.00 SF57 SCHOTT 1.821707 SF11...10.000000 PRIVATE CATALOG PWL 830.00 ’ TEO2 ’ 2.200000 REFRACT IVE :NDICES GLASS CODE 830.00 BK7 SCHCTT 1.510206 ’ TEO2 ’ 2.200000 39 Table 4.2.2-3. Mid...4.1-2 Acoustic Material Figure-of-Merit Trade 11 4.1-3 Degenerate Response in On-Axis TeO 2 12 4. 1-4 Rotated AO Interaction in TeO2 : High-Band Mode 13

The Study of the Phase Characteristics of Bragg Cells for Acousto-Optic Signal Processing

DTIC Science & Technology

1998-01-01

contractor will determine the relationship of phase characteristics between TeO2 and GaAs cells with their constructive and technical parameters. Design a...Braggcell TeO2 with minimal phase distortions operating near 100 MHz. Experimentally investigate the phase characteristics for a Bragg cell on TeO2 ...follows: The contractor will determine the relationship of phase characteristics between TeO2 and GaAs cells with their constructive and technical

Crystallization kinetic of Sb-V2O5-TeO2 glasses investigated by DSC and their elastic moduli and Poisson's ratio

NASA Astrophysics Data System (ADS)

Souri, Dariush

2015-01-01

Ternary tellurate glasses of the form xSb-(60-x)V2O5-40TeO2 (0≤x≤15 in mol%) were prepared by using the usual melt quenching method. Differential scanning calorimetry (DSC) at different heating rates (φ) was used to thermal analyze and to gain more insight in to the thermal stability, glass forming tendency and so calorimetric behavior of the present glasses. The glass transition temperature (Tg), the temperature corresponding to the onset of crystallization (Tx) and also the crystallization temperature (TCr) were obtained at different heating rates, to estimate the key kinetic parameter of activation energy of crystallization (ΔE) by using different empirical formulas. Also some other thermal parameters such as thermal stability and glass forming tendency were determined. It was found that Tg, Tx and TCr increase with increase in Sb content and also with increase in heating rate. Moreover, Makishima-Makenzie's theory was employed to evaluate the Poisson's ratio and elastic moduli, indicating a strong relation between elastic properties and the structure of glass. From the mechanical and thermal data and also the values of oxygen molar volume ( V O *), it was founded that the glass systems can be divided in to "two compositional regions"; so, results indicate that glasses with 10≤x≤15 (especially for x=12) are more thermal stable and strong glasses, which make them as more useful and promising materials in technological advantages and device manufacturing.

Photoinduced second-order optical susceptibilities of Er 2O 3 doped TeO 2-GeO 2-PbO glasses

NASA Astrophysics Data System (ADS)

Kassab, L. R. P.; Pinto, R. de A.; Kobayashi, R. A.; Piasecki, M.; Bragiel, P.; Kityk, I. V.

2007-06-01

Second-order optical susceptibilities were established in the optically poled erbium doped tellurite glasses near the melting temperature. The non-linear optical susceptibility was formed by bicolor coherent optical treatment performed by two coherent laser beams originated from 50 ps Nd-YAG laser ( λ = 1.32 μm) exciting the high pressure hydrogen laser cell emitting at 1907 nm. The non-centrosymmetric grating of the medium was created by coherent superposition of the fundamental laser illumination at 1907 nm and the doubled frequency one at 953.5 nm. The maximally all-optically poled SHG occurs for 2% doped Er 2O 3 (in weighting units) TeO 2-GeO 2-PbO glass. It was found that the photoinduced SHG demonstrates a saturation during the photo-treatment of 9-10 min using the two beams polarized at angle about 45° between them. During the coherent bicolor optical treatment it was achieved the value of second-order susceptibility up to 3.6 pm/V at 1907 nm. The optimal ratio between the fundamental beam with power density about 1.1 GW/cm 2 and writing doubled frequency seeding beam about 0.015 GW/cm 2 corresponds to the maximal of photoinduced SHG. For glasses with lower concentration of Er 2O 3, the relaxation of the second-order optical susceptibility is substantially longer and achieves SHG value that corresponds to 80% of the maximal ones. It is necessary to emphasize that efficient optically-poled grating exists only within the narrow temperature range near the glassing temperature. Possible physical mechanisms of the phenomenon observed are discussed. Generally the used glasses possess better parameters than early investigated germinate glasses.

Acute and subchronic toxicity as well as mutagenic evaluation of essential oil from turmeric (Curcuma longa L).

PubMed

Liju, Vijayasteltar B; Jeena, Kottarapat; Kuttan, Ramadasan

2013-03-01

The present study investigated the acute, subchronic and genotoxicity of turmeric essential oil (TEO) from Curcuma longa L. Acute administration of TEO was done as single dose up to 5 g of TEO per kg body weight and subchronic toxicity study for thirteen weeks was done by daily oral administration of TEO at doses 0.1, 0.25 and 0.5 g/kg b.wt. in Wistar rats. There were no mortality, adverse clinical signs or changes in body weight; water and food consumption during acute as well as subchronic toxicity studies. Indicators of hepatic function such as aspartate aminotransferase (AST), alanine amino transferase (ALT) and alkaline phosphatase (ALP) were unchanged in treated animals compared to untreated animals. Oral administration of TEO for 13 weeks did not alter total cholesterol, triglycerides, markers of renal function, serum electrolyte parameters and histopathology of tissues. TEO did not produce any mutagenicity to Salmonella typhimurium TA-98, TA-100, TA-102 and TA-1535 with or without metabolic activation. Administration of TEO to rats (1 g/kg b.wt.) for 14 days did not produce any chromosome aberration or micronuclei in rat bone marrow cells and did not produce any DNA damage as seen by comet assay confirming the non toxicity of TEO. Copyright © 2012 Elsevier Ltd. All rights reserved.

Fitness costs of various mobile genetic elements in Enterococcus faecium and Enterococcus faecalis

PubMed Central

Starikova, Irina; Al-Haroni, Mohammed; Werner, Guido; Roberts, Adam P.; Sørum, Vidar; Nielsen, Kaare M.; Johnsen, Pål J.

2013-01-01

Objectives To determine the fitness effects of various mobile genetic elements (MGEs) in Enterococcus faecium and Enterococcus faecalis when newly acquired. We also tested the hypothesis that the biological cost of vancomycin resistance plasmids could be mitigated during continuous growth in the laboratory. Methods Different MGEs, including two conjugative transposons (CTns) of the Tn916 family (18 and 33 kb), a pathogenicity island (PAI) of 200 kb and vancomycin-resistance (vanA) plasmids (80–200 kb) of various origins and classes, were transferred into common ancestral E. faecium and E. faecalis strains by conjugation assays and experimentally evolved (vanA plasmids only). Transconjugants were characterized by PFGE, S1 nuclease assays and Southern blotting hybridization analyses. Single specific primer PCR was performed to determine the target sites for the insertion of the CTns. The fitness costs of various MGEs in E. faecium and E. faecalis were estimated in head-to-head competition experiments, and evolved populations were generated in serial transfer assays. Results The biological cost of a newly acquired PAI and two CTns were both host- and insertion-locus-dependent. Newly acquired vanA plasmids may severely reduce host fitness (25%–27%), but these costs were rapidly mitigated after only 400 generations of continuous growth in the absence of antibiotic selection. Conclusions Newly acquired MGEs may impose an immediate biological cost in E. faecium. However, as demonstrated for vanA plasmids, the initial costs of MGE carriage may be mitigated during growth and beneficial plasmid–host association can rapidly emerge. PMID:23833178

Short-range structure and thermal properties of barium tellurite glasses

NASA Astrophysics Data System (ADS)

Kaur, Amarjot; Khanna, Atul; Gonzàlez, Fernando

2017-05-01

BaO-TeO2 glasses containing 10 to 20 BaO mol% were prepared and characterized by X-ray diffraction, density measurements, differential scanning calorimetry and Raman spectroscopy. Glass density decreases with increase in BaO concentration from 10 to 20 mol%, due to replacement of heavier TeO2 by lighter BaO, however glass transition temperature (Tg) increases significantly from a value of 318°C to 327°C due to increase in average single bond enthalpy of the tellurite network. Raman studies found that glass short-range structure consists of TeO4 and TeO3 structural units and BaO modifies the network by producing the structural transformation: TeO4→ TeO3.

A novel relay nucleus between the inferior colliculus and the optic tectum in the chicken (Gallus gallus).

PubMed

Niederleitner, Bertram; Gutierrez-Ibanez, Cristian; Krabichler, Quirin; Weigel, Stefan; Luksch, Harald

2017-02-15

Processing multimodal sensory information is vital for behaving animals in many contexts. The barn owl, an auditory specialist, is a classic model for studying multisensory integration. In the barn owl, spatial auditory information is conveyed to the optic tectum (TeO) by a direct projection from the external nucleus of the inferior colliculus (ICX). In contrast, evidence of an integration of visual and auditory information in auditory generalist avian species is completely lacking. In particular, it is not known whether in auditory generalist species the ICX projects to the TeO at all. Here we use various retrograde and anterograde tracing techniques both in vivo and in vitro, intracellular fillings of neurons in vitro, and whole-cell patch recordings to characterize the connectivity between ICX and TeO in the chicken. We found that there is a direct projection from ICX to the TeO in the chicken, although this is small and only to the deeper layers (layers 13-15) of the TeO. However, we found a relay area interposed among the IC, the TeO, and the isthmic complex that receives strong synaptic input from the ICX and projects broadly upon the intermediate and deep layers of the TeO. This area is an external portion of the formatio reticularis lateralis (FRLx). In addition to the projection to the TeO, cells in FRLx send, via collaterals, descending projections through tectopontine-tectoreticular pathways. This newly described connection from the inferior colliculus to the TeO provides a solid basis for visual-auditory integration in an auditory generalist bird. J. Comp. Neurol. 525:513-534, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

A P2-Type Layered Superionic Conductor Ga-Doped Na2 Zn2 TeO6 for All-Solid-State Sodium-Ion Batteries.

PubMed

Li, Yuyu; Deng, Zhi; Peng, Jian; Chen, Enyi; Yu, Yao; Li, Xiang; Luo, Jiahuan; Huang, Yangyang; Zhu, Jinlong; Fang, Chun; Li, Qing; Han, Jiantao; Huang, Yunhui

2018-01-24

Here, a P2-type layered Na 2 Zn 2 TeO 6 (NZTO) is reported with a high Na + ion conductivity ≈0.6×10 -3  S cm -1 at room temperature (RT), which is comparable to the currently best Na 1+n Zr 2 Si n P 3-n O 12 NASICON structure. As small amounts of Ga 3+ substitutes for Zn 2+ , more Na + vacancies are introduced in the interlayer gaps, which greatly reduces strong Na + -Na + coulomb interactions. Ga-substituted NZTO exhibits a superionic conductivity of ≈1.1×10 -3  S cm -1 at RT, and excellent phase and electrochemical stability. All solid-state batteries have been successfully assembled with a capacity of ≈70 mAh g -1 over 10 cycles with a rate of 0.2 C at 80 °C. 23 Na nuclear magnetic resonance (NMR) studies on powder samples show intra-grain (bulk) diffusion coefficients D NMR on the order of 12.35×10 -12  m 2  s -1 at 65 °C that corresponds to a conductivity σ NMR of 8.16×10 -3  S cm -1 , assuming the Nernst-Einstein equation, which thus suggests a new perspective of fast Na + ion conductor for advanced sodium ion batteries. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nd3+-doped TeO2-Bi2O3-ZnO transparent glass ceramics for laser application at 1.06 μm

NASA Astrophysics Data System (ADS)

Hu, Xiaolin; Luo, Zhiwei; Liu, Taoyong; Lu, Anxian

2017-04-01

The high crystallinity transparent glass ceramics based on Nd3+-doped 70TeO2-15Bi2O3-15ZnO (TBZ) compositions were successfully prepared by two-step heat treatment process. The effects of Nd2O3 content on the thermal, structural, mechanical, and optical properties of TBZ glass ceramics were studied. The incorporation of Nd2O3 enhanced the crystallization tendency in the matrix glass composition. The crystal phase and morphology of Bi2Te4O11 in the glass ceramics were confirmed by X-ray diffraction and field emission scanning electron microscopy. Due to precipitate more crystal phase, the hardness values increased from 3.21 to 3.66 GPa. Eight absorption peaks were observed from 400 to 900 nm and three emission bands appeared in the range of 850-1400 nm. With the increasing of Nd2O3 content from 0.5 to 2.5 wt%, the intensity of absorption peaks enhanced and the emission intensity increased up to 1.0 wt% and then fell down for further dopant concentration. The fluorescence decay lifetime decreased rapidly starting from 1.5 wt% Nd2O3 content due to the obvious energy migration among Nd3+. According to the extreme strong emission band around 1062 nm and the optimum Nd2O3 content (1.0 wt%), N10 glass ceramic was considered as a potential material for 1.06 μm laser applications.

Polysiloxanes derived from the controlled hydrolysis of tetraethoxysilane as precursors to silica for use in ceramic processing

NASA Technical Reports Server (NTRS)

Philipp, Warren H.

1990-01-01

Synthesis, properties, and potential applications in ceramic processing for two polysiloxane silica precursors derived from the controlled hydrolysis of tetraethoxysilane (TEOS) are presented. The higher molecular weight TEOS-A is a thick adhesive liquid of viscosity 8000 to 12,000 c.p. having a SiO2 char yield of about 55 percent. The lower molecular weight TEOS-B is a more fluid liquid of viscosity 150 to 200 c.p. having a SiO2 char yield of about 52 percent. The acid catalyzed hydrolysis of TEOS to hydrated silica gel goes through a series of polysiloxane intermediates. The rate of this transition increases with the quantity of water added to the TEOS; thus, for ease of polymer isolation, the amount of water added must be carefully determined so as to produce the desired polymer in a reasonable time. The water to TEOS mole ratio falls in the narrow range of 1.05 for TEOS-A and 0.99 for TEOS-B. Further polymerization or gelation is prevented by storing at -5 C in a freezer. Both polysiloxanes thermoset to a glassy solid at 115 C. The liquid polymers are organic in nature in that they are miscible with toluene and ethanol, slightly souble in heptane, but immiscible with water. For both polymers, results on viscosity versus time are given at several temperatures and water additions. Based on these results, some examples of practical utilization of the precursors for ceramic fabrication are given.

Short-range structure and thermal properties of lead tellurite glasses

NASA Astrophysics Data System (ADS)

Hirdesh, Kaur, Amarjot; Khanna, Atul; Gonzàlez, Fernando

2017-05-01

PbO-TeO2 glasses having composition: xPbO-(100 - x)TeO2 (x = 10, 15 and 20 mol%) were prepared by melt quenching and characterized by X-ray diffraction, density measurements, differential scanning calorimetry and Raman spectroscopy. Glass density increases from 5.89 to 6.22 g cm-3 with increase in PbO concentration from 10 to 20 mol%, due to the replacement of TeO2 by heavier PbO. DSC studies found that glass transition temperature (Tg) decreases from a value of 295°C to 281°C. Raman studies found that glass short-range structure consists of TeO4 and TeO3 structural units and that PbO modifies the network by the structural transformation: TeO4 to TeO3.

Prospective experimental study of transrectal viscerotomy closure using transanal endoscopic suture vs. circular stapler: a step toward NOTES.

PubMed

Diana, M; Leroy, J; Wall, J; De Ruijter, V; Lindner, V; Dhumane, P; Mutter, D; Marescaux, J

2012-06-01

Endoluminal full-thickness closure of the rectal wall is critical in emerging procedures including endoscopic submucosal dissection and transrectal natural orifice transluminal endoscopic surgery (NOTES). This study aimed to compare manual suture using the transanal endoscopic operation platform (TEO; Karl Storz, Tüttlingen, Germany) with the end-to-end anastomosis hemorrhoid circular stapler (EEA; Covidien, Dublin, Ireland) for closure of the rectal viscerotomy during transrectal NOTES segmental colectomy. A total of 12 swine underwent transrectal hybrid NOTES partial colectomies. Animals were divided into two groups according to the viscerotomy closure technique: 1) TEO manual suture; 2) EEA circular stapler closure. Mean (± SD) viscerotomy closure time was 67.5 ± 59.5 minutes and 31.5 ± 19.6 minutes for TEO and EEA, respectively. There was one conversion to laparoscopy in the TEO group and a misfiring in the EEA group that required a TEO salvage suture. There was one positive air-leak test in each group. Peritoneal fluid collected at the end of the procedure tested positive for bacterial contamination in all cases. A mild stenosis was present in 4 /6 viscerotomies (67 %) in the TEO group and in 1/6 (17 %) in the EEA group on endoscopic control. Inflammatory changes were mild in 3/5 (60 %) and 4/5 (80 %) viscerotomies in the TEO and EEA groups, respectively, whereas severe inflammation was found in 2/5 (TEO) and 1 /5 (EEA). Transrectal viscerotomy closure using the EEA circular stapler technique is feasible, easy to perform, and histologically comparable to suture closure through a TEO platform. It may offer an attractive alternative for NOTES segmental colectomies and endoscopic resections. © Georg Thieme Verlag KG Stuttgart · New York.

Skipjack tuna (Katsuwonus pelamis) eyeball oil exerts an anti-inflammatory effect by inhibiting NF-κB and MAPK activation in LPS-induced RAW 264.7 cells and croton oil-treated mice.

PubMed

Jeong, Da-Hyun; Kim, Koth-Bong-Woo-Ri; Kim, Min-Ji; Kang, Bo-Kyeong; Ahn, Dong-Hyun

2016-11-01

The effect of tuna eyeball oil (TEO) on lipopolysaccharide (LPS)-induced inflammation in macrophage cells was investigated. TEO had no cytotoxicity in cell viability as compared to the control in LPS induced RAW 264.7 cells. TEO reduced the levels of NO and pro-inflammatory cytokines by up to 50% in a dose-dependent manner. The expression of NF-κB and MAPKs as well as iNOS and COX-2 proteins was reduced by TEO, which suggests that its anti-inflammatory activity is related to the suppression of the NF-κB and MAPK signaling pathways. The rate of formation of ear edema was reduced compared to that in the control at the highest dose tested. In an acute toxicity test, no mice were killed by TEO doses of up to 5000mg/kg body weight during the two week observation period. These results suggested that TEO may have a significant effect on inflammatory factors and be a potential anti-inflammatory therapeutic. Copyright © 2016 Elsevier B.V. All rights reserved.

Vancomycin-resistant gene identification from live bacteria on an integrated microfluidic system by using low temperature lysis and loop-mediated isothermal amplification

PubMed Central

Chang, Wen-Hsin; Yu, Ju-ching; Yang, Sung-Yi; Lin, Yi-Cheng; Wang, Chih-Hung; You, Huey-Ling; Wu, Jiunn-Jong; Lee, Gwo-Bin

2017-01-01

Vancomycin-resistant Enterococcus (VRE) is a kind of enterococci, which shows resistance toward antibiotics. It may last for a long period of time and meanwhile transmit the vancomycin-resistant gene (vanA) to other bacteria. In the United States alone, the resistant rate of Enterococcus to vancomycin increased from a mere 0.3% to a whopping 40% in the past two decades. Therefore, timely diagnosis and control of VRE is of great need so that clinicians can prevent patients from becoming infected. Nowadays, VRE is diagnosed by antibiotic susceptibility test or molecular diagnosis assays such as matrix-assisted laser desorption ionization/time-of-flight mass spectrometry and polymerase chain reaction. However, the existing diagnostic methods have some drawbacks, for example, time-consumption, no genetic information, or high false-positive rate. This study reports an integrated microfluidic system, which can automatically identify the vancomycin resistant gene (vanA) from live bacteria in clinical samples. A new approach using ethidium monoazide, nucleic acid specific probes, low temperature chemical lysis, and loop-mediated isothermal amplification (LAMP) has been presented. The experimental results showed that the developed system can detect the vanA gene from live Enterococcus in joint fluid samples with detection limit as low as 10 colony formation units/reaction within 1 h. This is the first time that an integrated microfluidic system has been demonstrated to detect vanA gene from live bacteria by using the LAMP approach. With its high sensitivity and accuracy, the proposed system may be useful to monitor antibiotic resistance genes from live bacteria in clinical samples in the near future. PMID:28798845

Effect of lithium on thermal and structural properties of zinc vanadate tellurite glass

NASA Astrophysics Data System (ADS)

Rani, Sunita; Kundu, R. S.; Ahlawat, Neetu; Rani, Suman; Sangwan, Kanta Maan; Ahlawat, Navneet

2018-04-01

Glasses having composition 60TeO2-15V2O5-(25-x) ZnO-xLi2O where x= 0, 5, 10 mol% were prepared by standard melt quench technique. The glass transition temperature is measured by DSC technique using TA instrument and found to decrease with increase in Li2O signifies that glass formation tendency, thermal stability and compactness of glass structure decreases. The deconvolution of FTIR spectra evidenced the existence of TeO4, TeO3 and TeO6 structural units in glass network and vanadium exists as VO4 and VO5 structural units.

Optical Signal Processing.

DTIC Science & Technology

1983-11-30

be large if s is highly negative, which is the Poynting vector, the same singularity function can be case for TeO2 operated in the slow-shear mode...we give the values of the elastic coefficients for PbMoO 4 and TeO2 from which we calculate that s = -0.176 for PbMoO 4 and s = 0.274 for TeO 2. Our...lowest for TeO2 and highest for PbMoO 4; the rate for fused quartz is nearly halfway between these two values. The diffraction patterns produced by

FTIR, Raman, and UV-Vis spectroscopic and DFT investigations of the structure of iron-lead-tellurate glasses.

PubMed

Rada, Simona; Dehelean, Adriana; Culea, Eugen

2011-08-01

In this work, the effects of iron ion intercalations on lead-tellurate glasses were investigated via FTIR, Raman and UV-Vis spectroscopies. This homogeneous glass system has compositions xFe(2)O(3)·(100-x)[4TeO(2)·PbO(2)], where x = 0-60 mol%. The presented observations in these mechanisms show that the lead ions have a pronounced affinity towards [TeO(3)] structural units, resulting in the deformation of the Te-O-Te linkages, and leading to the intercalation of [PbO( n )] (n = 3, 4) and [FeO( n )] (n = 4, 6) entities in the [TeO(4)] chain network. The formation of negatively charged [FeO(4)](1-) structural units implies the attraction of Pb(2+) ions in order to compensate for this electrical charge. Upon increasing the Fe(2)O(3) content to 60 mol%, the network can accommodate an excess of oxygen through the formation of [FeO(6)] structural units and the conversion of [TeO(4)] into [TeO(3)] structural units. For even higher Fe(2)O(3) contents, Raman spectra indicate a greater degree of depolymerization of the vitreous network than FTIR spectra do. The bands due to the Pb-O bond vibrations are very strongly polarized and the [TeO(4)] structural units convert into [TeO(3)] units via an intermediate coordination stage termed "[TeO(3+1)]" structural units. Our UV-Vis spectroscopic data show two mechanisms: (i) the conversion of the Fe(3+) to Fe(2+) at the same time as the oxidation of Pb(2+) to Pb(+4) ions for samples with low Fe(2)O(3) contents; (ii) when the Fe(2)O(3) content is high (x ≥ 50 mol%), the Fe(2+) ions capture positive holes and are transferred to Fe(3+) ions through a photochemical reaction, while the Pb(2+) ions are formed by the reduction of Pb(4+) ions. DFT calculations show that the addition of Fe(2)O(3) to lead-tellurate glasses seems to break the axial Te-O bonds, and the [TeO(4)] structural units are gradually transformed into [TeO(3+1)]- and [TeO(3)]-type polyhedra. Analyzing these data further indicates a gradual

Persistence of Animal and Human Glycopeptide-Resistant Enterococci on Two Norwegian Poultry Farms Formerly Exposed to Avoparcin Is Associated with a Widespread Plasmid-Mediated vanA Element within a Polyclonal Enterococcus faecium Population

PubMed Central

Johnsen, P. J.; Østerhus, J. I.; Sletvold, H.; Sørum, M.; Kruse, H.; Nielsen, K.; Simonsen, G. S.; Sundsfjord, A.

2005-01-01

The evolutionary processes responsible for the long-term persistence of glycopeptide-resistant Enterococcus faecium (GREF) in nonselective environments were addressed by genetic analyses of E. faecium populations in animals and humans on two Norwegian poultry farms that were previously exposed to avoparcin. A total of 222 fecal GREF (n = 136) and glycopeptide-susceptible (n = 86) E. faecium (GSEF) isolates were obtained from farmers and poultry on three separate occasions in 1998 and 1999. Pulsed-field gel electrophoresis (PFGE) and plasmid DNA analyses discerned 22 GREF and 32 GSEF PFGE types within shifting polyclonal animal and human E. faecium populations and indicated the presence of transferable plasmid-mediated vanA resistance, respectively. Examples of dominant, persistent GREF PFGE types supported the notion that environmentally well-adapted GREF types may counteract the reversal of resistance. PFGE analyses, sequencing of the purK housekeeping gene, and partial typing of vanA-containing Tn1546 suggested a common animal and human reservoir of glycopeptide resistance. Inverse PCR amplification and sequence analyses targeting the right end of the Tn1546-plasmid junction fragment strongly indicated the presence of a common single Tn1546-plasmid-mediated element in 20 of 22 GREF PFGE types. This observation was further strengthened by vanY-vanZ hybridization analyses of plasmid DNAs as well as the finding of a physical linkage between Tn1546 and a putative postsegregation killing system for seven GREF PFGE types. In conclusion, our observations suggest that the molecular unit of persistence of glycopeptide resistance is a common mobile plasmid-mediated vanA-containing element within a polyclonal GREF population that changes over time. In addition, we propose that “plasmid addiction systems” may contribute to the persistence of GREF in nonselective environments. PMID:15640183

Measurements of defect structures by positron annihilation lifetime spectroscopy of the tellurite glass TeO2-P2O5-ZnO-LiNbO3 doped with ions of rare earth elements: Er3+, Nd3+ and Gd3+

NASA Astrophysics Data System (ADS)

Golis, E.; Yousef, El. S.; Reben, M.; Kotynia, K.; Filipecki, J.

2015-12-01

The objective of the study was the structural analysis of the TeO2-P2O5-ZnO-LiNbO3 tellurite glasses doped with ions of the rare-earth elements: Er3+, Nd3+ and Gd3+ based on the PALS (Positron Annihilation Lifetime Spectroscopy) method of measuring positron lifetimes. Values of positron lifetimes and the corresponding intensities may be connected with the sizes and number of structural defects, such as vacancies, mono-vacancies, dislocations or pores, the sizes of which range from a few angstroms to a few dozen nanometres. Experimental positron lifetime spectrum revealed existence of two positron lifetime components τ1 and τ2. Their interpretation was based on two-state positron trapping model where the physical parameters are the annihilation velocity and positron trapping rate.

Anti-arthritic effects and toxicity of the essential oils of turmeric (Curcuma longa L.).

PubMed

Funk, Janet L; Frye, Jennifer B; Oyarzo, Janice N; Zhang, Huaping; Timmermann, Barbara N

2010-01-27

Turmeric (Curcuma longa L., Zingiberaceae) rhizomes contain two classes of secondary metabolites, curcuminoids and the less well-studied essential oils. Having previously identified potent anti-arthritic effects of the curcuminoids in turmeric extracts in an animal model of rheumatoid arthritis (RA), studies were undertaken to determine whether the turmeric essential oils (TEO) were also joint protective using the same experimental model. Crude or refined TEO extracts dramatically inhibited joint swelling (90-100% inhibition) in female rats with streptococcal cell wall (SCW)-induced arthritis when extracts were administered via intraperitoneal injection to maximize uniform delivery. However, this anti-arthritic effect was accompanied by significant morbidity and mortality. Oral administration of a 20-fold higher dose TEO was nontoxic, but only mildly joint-protective (20% inhibition). These results do not support the isolated use of TEO for arthritis treatment but, instead, identify potential safety concerns in vertebrates exposed to TEO.

Anti-Arthritic Effects and Toxicity of the Essential Oils of Turmeric (Curcuma longa L.)

PubMed Central

Funk, Janet L.; Frye, Jennifer B.; Oyarzo, Janice N.; Zhang, Huaping; Timmermann, Barbara N.

2010-01-01

Turmeric (Curcuma longa L., Zingiberaceae) rhizomes contain two classes of secondary metabolites, curcuminoids and the less well-studied essential oils. Having previously identified potent anti-arthritic effects of the curcuminoids in turmeric extracts in an animal model of rheumatoid arthritis (RA), studies were undertaken to determine whether the turmeric essential oils (TEO) were also joint protective using the same experimental model. Crude or refined TEO extracts dramatically inhibited joint swelling (90-100% inhibition) in female rats with streptococcal cell wall (SCW)-induced arthritis when extracts were administered via intraperitoneal injection to maximize uniform delivery. However, this anti-arthritic effect was accompanied by significant morbidity and mortality. Oral administration of a 20-fold higher dose TEO was non-toxic, but only mildly joint-protective (20% inhibition). These results do not support the isolated use of TEO for arthritis treatment, but, instead, identify potential safety concerns in vertebrates exposed to TEO. PMID:20025215

Supercritical Fluid Atomic Layer Deposition: Base-Catalyzed Deposition of SiO2.

PubMed

Kalan, Roghi E; McCool, Benjamin A; Tripp, Carl P

2016-07-19

An in situ FTIR thin film technique was used to study the sequential atomic layer deposition (ALD) reactions of SiCl4, tetraethyl orthosilicate (TEOS) precursors, and water on nonporous silica powder using supercritical CO2 (sc-CO2) as the solvent. The IR work on nonporous powders was used to identify the reaction sequence for using a sc-CO2-based ALD to tune the pore size of a mesoporous silica. The IR studies showed that only trace adsorption of SiCl4 occurred on the silica, and this was due to the desiccating power of sc-CO2 to remove the adsorbed water from the surface. This was overcome by employing a three-step reaction scheme involving a first step of adsorption of triethylamine (TEA), followed by SiCl4 and then H2O. For TEOS, a three-step reaction sequence using TEA, TEOS, and then water offered no advantage, as the TEOS simply displaced the TEA from the silica surface. A two-step reaction involving the addition of TEOS followed by H2O in a second step did lead to silica film growth. However, higher growth rates were obtained when using a mixture of TEOS/TEA in the first step. The hydrolysis of the adsorbed TEOS was also much slower than that of the adsorbed SiCl4, and this was overcome by using a mixture of water/TEA during the second step. While the three-step process with SiCl4 showed a higher linear growth rate than obtained with two-step process using TEOS/TEA, its use was not practical, as the HCl generated led to corrosion of our sc-CO2 delivery system. However, when applying the two-step ALD reaction using TEOS on an MCM-41 powder, a 0.21 nm decrease in pore diameter was obtained after the first ALD cycle whereas further ALD cycles did not lead to further pore size reduction. This was attributed to the difficulty in removal of the H2O in the pores after the first cycle.

Validation of VITEK 2 Version 4.01 Software for Detection, Identification, and Classification of Glycopeptide-Resistant Enterococci

PubMed Central

Abele-Horn, Marianne; Hommers, Leif; Trabold, René; Frosch, Matthias

2006-01-01

We evaluated the ability of the new VITEK 2 version 4.01 software to identify and detect glycopeptide-resistant enterococci compared to that of the reference broth microdilution method and to classify them into the vanA, vanB, vanC1, and vanC2 genotypes. Moreover, the accuracy of antimicrobial susceptibility testing with agents with improved potencies against glycopeptide-resistant enterococci was determined. A total of 121 enterococci were investigated. The new VITEK 2 software was able to identify 114 (94.2%) enterococcal strains correctly to the species level and to classify 119 (98.3%) enterococci correctly to the glycopeptide resistance genotype level. One Enterococcus casseliflavus strain and six Enterococcus faecium vanA strains with low-level resistance to vancomycin were identified with low discrimination, requiring additional tests. One of the vanA strains was misclassified as the vanB type, and one glycopeptide-susceptible E. facium wild type was misclassified as the vanA type. The overall essential agreements for antimicrobial susceptibility testing results were 94.2% for vancomycin, 95.9% for teicoplanin, 100% for quinupristin-dalfopristin and moxifloxacin, and 97.5% for linezolid. The rates of minor errors were 9% for teicoplanin and 5% for the other antibiotic agents. The identification and susceptibility data were produced within 4 h to 6 h 30 min and 8 h 15 min to 12 h 15 min. In conclusion, use of VITEK 2 version 4.01 software appears to be a reliable method for the identification and detection of glycopeptide-resistant enterococci as well as an improvement over the use of the former VITEK 2 database. However, a significant reduction in the detection time would be desirable. PMID:16390951

Vancomycin-resistance phenotypes, vancomycin-resistance genes, and resistance to antibiotics of enterococci isolated from food of animal origin.

PubMed

Gousia, Panagiota; Economou, Vangelis; Bozidis, Petros; Papadopoulou, Chrissanthy

2015-03-01

In the present study, 500 raw beef, pork, and chicken meat samples and 100 pooled egg samples were analyzed for the presence of vancomycin-resistant enterococci, vancomycin-resistance phenotypes, and resistance genes. Of 141 isolates of enterococci, 88 strains of Enterococcus faecium and 53 strains of E. faecalis were identified. The most prevalent species was E. faecium. Resistance to ampicillin (n = 93, 66%), ciprofloxacin (n = 74, 52.5%), erythromycin (n = 73, 51.8%), penicillin (n = 59, 41.8%) and tetracycline (n = 52, 36.9%) was observed, while 53.2% (n = 75) of the isolates were multiresistant and 15.6% (n = 22) were susceptible to all antibiotics. Resistance to vancomycin was exhibited in 34.1% (n = 30) of the E. faecium isolates (n = 88) and 1.9% (n = 1) of the E. faecalis isolates (n = 53) using the disc-diffusion test and the E-test. All isolates were tested for vanA and vanB using real-time polymerase chain reaction (PCR) and multiplex PCR, and for vanC, vanD, vanE, vanG genes using multiplex PCR only. Among E. faecalis isolates, no resistance genes were identified. Among the E. faecium isolates, 28 carried the vanA gene when tested by multiplex PCR and 29 when tested with real-time PCR. No isolate carrying the vanC, vanD, vanE, or vanG genes was identified. Melting-curve analysis of the positive real-time PCR E. faecium isolates showed that 22 isolates carried the vanA gene only, 2 isolates the vanB2,3 genes only, and seven isolates carried both the vanA and vanB2,3 genes. Enterococci should be considered a significant zoonotic pathogen and a possible reservoir of genes encoding resistance potentially transferred to other bacterial species.

Structure of alkali tellurite glasses from neutron diffraction and molecular orbital calculations

NASA Astrophysics Data System (ADS)

Niida, Haruki; Uchino, Takashi; Jin, Jisun; Kim, Sae-Hoon; Fukunaga, Toshiharu; Yoko, Toshinobu

2001-01-01

The structure of pure TeO2 and alkali tellurite glasses has been examined by neutron diffraction and ab initio molecular orbital methods. The experimental radial distribution functions along with the calculated results have demonstrated that the basic structural units in tellurite glasses change from highly strained TeO4 trigonal bipyramids to more regular TeO3 trigonal pyramids with increasing alkali content. It has also been shown that the TeO3 trigonal pyramids do not exist in the form of isolated units in the glass network but interact with each other to form intertrigonal Te⋯O linkages. The present results suggest that nonbridging oxygen (NBO) atoms in tellurite glasses do not exist in their "pure" form; that is, all the NBO atoms in TeO3 trigonal bipyramids will interact with the first- and/or second-neighbor Te atoms, resulting in the three-dimensional continuous random network even in tellurite glasses with over 30 mol % of alkali oxides.

Triple modifier effect on physical, optical and structural properties of boro tellurite zinc lithium glasses

NASA Astrophysics Data System (ADS)

Naresh, P.; Srinivasu, D.; Narsimlu, N.; Ch. Srinivas, Kavitha, B.; Deshpandhe, Uday; Kumar, K. Siva

2018-05-01

To investigate physical, optical and structural properties of glass samples of the Quaternary system (60-x)B2O3-xTeO2-10ZnO-30Li2O with x=0,5,10,15, and 20 mol% were prepared by conventional melt quenching technique. XRD confirmed the amorphous nature of all samples. Physical parameters like density, molar volume, Oxygen packing density and etc. calculated. Density of glass samples increased with the increase of TeO2 concentration due to the replacement of lighter B2O3 with heavier TeO2. Optical properties has studied with the help of UV-Visible spectra. Cut off wavelength is increases whereas Eopt and Urbache energies is decreased except intermediate mole fraction of TeO2 at which the triple modifier effect can be observed. Fourier Transform Infrared spectroscopy reveals that the network consists of TeO3 and TeO6 structural units along with BO3 and BO4 units.

Structural and optical study of tellurite-barium glasses

NASA Astrophysics Data System (ADS)

Grelowska, I.; Reben, M.; Burtan, B.; Sitarz, M.; Cisowski, J.; Yousef, El Sayed; Knapik, A.; Dudek, M.

2016-12-01

The goal of this work was to determine the effect of barium oxide on the structural, thermal and optical properties of the TeO2-BaO-Na2O (TBN) and TeO2-BaO-WO3 (TBW) glass systems. Raman spectra allow relating the glass structure and vibration properties (i.e. vibrational frequencies and Raman intensities) with the glass composition. Raman spectra show the presence of TeO4 and TeO3+1/TeO3 units that conform with the glass matrix. Differential thermal analysis DTA, XRD measurements have been considered in term of BaO addition. The spectral dependence of ellipsometric angles of the tellurite-barium glass has been studied. The optical measurements were conducted on Woollam M2000 spectroscopic ellipsometer in spectral range of 190-1700 nm. The reflectance and transmittance measurements have been done on spectrophotometer Perkin Elmer, Lambda 900 in the range of 200-2500 nm (UV-VIS-NIR). From the transmittance spectrum, the energy gap was determined.

Thermal and structural properties of zinc modified tellurite based glasses

NASA Astrophysics Data System (ADS)

Kundu, R. S.; Dhankhar, Sunil; Punia, R.; Dult, Meenakshi; Kishore, N.

2016-05-01

Glass system 60 TeO2 - 10 B2O3-(30-x) Bi2O3-x ZnO with mole fraction x = 10, 15, 20, 25 and 30 were synthesized by conventional melt quenching technique under controlled atmospheric conditions. The glass transition temperature (Tg) has been determined using differential scanning Calorimetry (DSC) and its value is observed to increase with increase in ZnO content. This increase may be due to the increase in the concentration of the bridging oxygen (BO) atoms. IR and Raman spectra of the present glass system indicate that ZnO acts as network modifier and exists in ZnO4 units. TeO2 exists as TeO3, TeO4, and TeO3+1 structural units. Bismuth plays the role of network modifier with BiO6 octahedral structural units whereas B2O3 exists in the form of BO3 trigonal and BO4 tetrahedral structural units.

Low prevalence of vancomycin- and bifunctional aminoglycoside-resistant enterococci isolated from poultry farms in Malaysia.

PubMed

Chan, Yean Yean; Abd Nasir, Mohd Hafiz B; Yahaya, Mohd Azli B; Salleh, Noor Mohamad Amin B; Md Dan, Azril Deenor B; Musa, Abd Majid B; Ravichandran, M

2008-02-29

A total of 225 samples from poultry farms and the surrounding environment were screened for vancomycin-resistant enterococci (VRE) and bifunctional aminoglycoside-resistant enterococci using conventional microbiological tests and a nanoplex polymerase chain reaction (PCR) assay. Three (1.3%) of the samples were found to contain vancomycin-resistant isolates (MIC>256 microg/mL) that had a vanA genotype. The three vanA positive VRE isolates were identified as different species. Only one isolate (Enterococcus faecium F 4/13_54) was sensitive to teicoplanin (MIC<0. 12-0.35 microg/mL); the other two VRE (E. faecalis A 21_35 and E. gallinarum F 5/10_1) were resistant to teicoplanin (MIC 3.6-->16 microg/mL). The vanC genotype was observed in nine (4%) of the samples collected. High-level gentamicin-resistant (HLGR) enterococci (with MIC ranging between 100 and 500 microg/mL) were detected in 44 samples. However, only 40 of these were found to possess the aac(6')-aph(2'') gene. The overall prevalence of VRE among the samples from the poultry farms and environment was 5.3%, but the prevalence of the clinically significant vanA VRE was 1.3%, and the prevalence of bifunctional aminoglycoside-resistant enterococci was slightly higher, at 19.5%.

Optical properties of nanocrystalline potassium lithium niobate in the glass system (100-x) TeO2-x(1.5K2O-Li2O-2.5Nb2O5).

PubMed

Ahamad, M Niyaz; Varma, K B R

2009-08-01

Optically clear glasses of various compositions in the system (100-x) TeO2-x(1.5K2O-Li2O-2.5Nb2O5) (2 < or = x < or = 12, in molar ratio) were prepared by the melt-quenching technique. The glassy nature of the as-quenched samples was established via differential scanning calorimetry (DSC). The amorphous and the crystalline nature of the as-quenched and heat-treated samples were confirmed by the X-ray powder diffraction and transmission electron microscopic (TEM) studies. Transparent glasses comprising potassium lithium niobate (K3Li2Nb5O15) microcrystallites on the surface and nanocrystallites within the glass were obtained by controlled heat-treatment of the as-quenched glasses just above the glass transition temperature (T(g)). The optical transmission spectra of these glasses and glass-crystal composites of various compositions were recorded in the 200-2500 nm wavelength range. Various optical parameters such as optical band gap, Urbach energy, refractive index were determined. Second order optical non-linearity was established in the heat-treated samples by employing the Maker-Fringe method.

The Role of Adaptive Photorefractive Power Limiting on Acousto-Optic Radio Frequency (RF) Signal Excision

DTIC Science & Technology

2001-12-01

using TeO2 , A-O cell, slow acoustic wave). Beam deflection is a continuous function of the input voltage power spectrum; however, the spot width...than for isotropic crystals. Thus, anisotropic, A-O materials, such as TeO2 , have advantages for high RF bandwidth; slow acoustic speeds give better...112 Unfortunately, signal resolution worsened because the new TeO2 crystal was designed to operate in the longitudinal acoustic mode, ua = 5.5 Km

Defense Small Business Innovation Research (SBIR) Program. Program Solicitation 90.1. FY-1990

DTIC Science & Technology

1989-10-01

Electronics Assemble and Test A90-125 Guided-Wave TeO2 Optical Devices A90-126 Acceleration Sensing Module for Munition Safety Systems A90-127 Electromagnetic...package containing all drawings and process information, complete operating manuals. A90-125 Guided-Wave TeO2 Optical Devices OBJECTIVE: This exploratory...bandwidth and efficiency of these devices. PHASE I: Phase one would consist of the design of several breadboard TeO2 AO devices each having TBWP of

Structural and optical properties of lead-boro-tellurrite glasses induced by gamma-ray.

PubMed

Mustafa, Iskandar Shahrim; Kamari, Halimah Mohamed; Yusoff, Wan Mohd Daud Wan; Aziz, Sidek Abdul; Rahman, Azhar Abdul

2013-02-04

Spectrophotometric studies of lead borotellurite glasses were carried out before and after gamma irradiation exposure. The increasing peak on the TeO(4) bi-pyramidal arrangement and TeO(3+1) (or distorted TeO(4)) is due to augmentation of irradiation dose which is attributed to an increase in degree of disorder of the amorphous phase. The structures of lead tellurate contain Pb(3)TeO(6) consisting of TeO(3) trigonal pyramid connected by PbO(4) tetragonal forming a three-dimensional network. The decrease of glass rigidity is due to irradiation process which is supported by the XRD diffractograms results. The decreasing values of absorption edge indicate that red shift effect occur after irradiation processes. A shift in the optical absorption edge attributed to an increase of the conjugation length. The values of optical band gap, E(opt) were calculated and found to be dependent on the glass composition and radiation exposure. Generally, an increase and decrease in Urbach's energy can be considered as being due to an increase in defects within glass network.

Structural and Optical Properties of Lead-Boro-Tellurrite Glasses Induced by Gamma-Ray

PubMed Central

Mustafa, Iskandar Shahrim; Kamari, Halimah Mohamed; Yusoff, Wan Mohd Daud Wan; Aziz, Sidek Abdul; Rahman, Azhar Abdul

2013-01-01

Spectrophotometric studies of lead borotellurite glasses were carried out before and after gamma irradiation exposure. The increasing peak on the TeO4 bi-pyramidal arrangement and TeO3+1 (or distorted TeO4) is due to augmentation of irradiation dose which is attributed to an increase in degree of disorder of the amorphous phase. The structures of lead tellurate contain Pb3TeO6 consisting of TeO3 trigonal pyramid connected by PbO4 tetragonal forming a three-dimensional network. The decrease of glass rigidity is due to irradiation process which is supported by the XRD diffractograms results. The decreasing values of absorption edge indicate that red shift effect occur after irradiation processes. A shift in the optical absorption edge attributed to an increase of the conjugation length. The values of optical band gap, Eopt were calculated and found to be dependent on the glass composition and radiation exposure. Generally, an increase and decrease in Urbach’s energy can be considered as being due to an increase in defects within glass network. PMID:23380963

Structural and luminescent study of TeO2-BaO-Bi2O3-Ag glass system doped with Eu3+ and Dy3+ for possible color-tunable phosphor application

NASA Astrophysics Data System (ADS)

Lewandowski, Tomasz; Seweryński, Cezary; Walas, Michalina; Łapiński, Marcin; Synak, Anna; Sadowski, Wojciech; Kościelska, Barbara

2018-05-01

Tellurite glass systems of 73TeO2-4BaO-3Bi2O3-1Ag:xEu2O3-(2-x)Dy2O3 (where x = 0.5, 1, 1.5, 2 in molar ratio) composition have been successfully synthesized. In order to acquire Ag nanoparticles, materials have been heat treated at 350 °C in the air atmosphere. Structural properties of obtained samples were evaluated with various techniques. X-Ray Diffraction (XRD) measurements indicated that obtained materials are amorphous in nature. UV-vis results presented transitions characteristic to Dy3+ and Eu3+ ions. Additionally, X-Ray Photoelectron Spectroscopy (XPS) analysis indicated the presence of silver in metallic form. Photoluminescence measurements shown influence of Ag nanoparticles on emission characteristics. Simultaneous emission of Dy3+ and Eu3+ has been observed when samples were excited with λexc = 390 nm. Change of the emission color induced by heat treatment has been observed and described in case of x = 1 glass series. According to CIE results emission color changes as Eu/Dy ratio and heat treatment time are changed. Emission shifts from reddish-orange to yellowish white color. Obtained photoluminescence results confirm that synthesized materials are good candidates for color tunable phosphors.

Accuracy of the VITEK 2 System To Detect Glycopeptide Resistance in Enterococci

PubMed Central

van den Braak, Nicole; Goessens, Wil; van Belkum, Alex; Verbrugh, Henri A.; Endtz, Hubert P.

2001-01-01

We evaluated the accuracy of the VITEK 2 fully automated system to detect and identify glycopeptide-resistant enterococci (GRE) compared to a reference agar dilution method. The sensitivity of vancomycin susceptibility testing with VITEK 2 for the detection of vanA, vanB, and vanC1 strains was 100%. The sensitivity of vancomycin susceptibility testing of vanC2 strains was 77%. The sensitivity of teicoplanin susceptibility testing of vanA strains was 90%. Of 80 vanC enterococci, 78 (98%) were correctly identified by VITEK 2 as Enterococcus gallinarum/Enterococcus casseliflavus. Since the identification and susceptibility data are produced within 3 and 8 h, respectively, VITEK 2 appears a fast and reliable method for detection of GRE in microbiology laboratories. PMID:11136798

An Integrated Approach to the Detection, Localization, and Classification of Mines

DTIC Science & Technology

2002-04-30

the TeO2 AOTF used here. In this work our imaging system was limited to wavelengths shorter than 700 nm. Thus to demonstrate the capabilities of an...is diagrammed in Figure 4 and employs a TeO2 AOTF (Brimrose, Inc. tunable from 450 to 700 nm), a thermoelectrically cooled CCD (Santa Barbara...which were filled with sand in the wavelength-resolved images. The best images in RF signal generator TeO2 AOTF light at selected wavelength (6° tilt

Multiscale Mass-Spring Models of Carbon Nanotube Foams

DTIC Science & Technology

2010-09-06

Mesarovic et al., 2007). The study of thin structural foams (Gibson and Ashby, 1998) for cushioning (Zhang et al., 2009), energy dissipation ( Teo et al...compressible foam-like behavior under compressive cycling loads (Suhr et al., 2007; Teo et al., 2007; Tao et al., 2008; Deck et al., 2007; Cao et al., 2005). 2...and electrostatic interaction be- tween individual and bundles of carbon nanotubes (Suhr et al., 2007; Teo et al., 2007; Tao et al., 2008; Deck et al

Antibiotic resistance and molecular characterization of probiotic and clinical Lactobacillus strains in relation to safety aspects of probiotics.

PubMed

Klein, Günter

2011-02-01

The evaluation of the safety of probiotic strains includes the exclusion of antibiotic resistance of clinical importance. Ninety-two strains from the genus Lactobacillus isolated from probiotics, food, and clinical sources were included in the investigation. Species tested were the L. acidophilus group, L. casei group, L. reuteri/fermentum group, and L. sakei/curvatus group. Cell and colony morphology, fermentation patterns, and growth characteristics as well as soluble whole cell proteins were analyzed. Antibiotic resistance against clinically important agents was determined by broth dilution tests. The vanA and tet genes were confirmed. Resistances occurred mainly against gentamicin, ciprofloxacin, clindamycin, sulfonamides, and, in some cases, glycopeptides. The natural glycopeptide resistance within the L. casei group and L. reuteri appears to be not of clinical relevance, as there was no vanA gene present. Therefore, the transfer of this resistance is very unlikely. Tet-(A), -(B), -(C), -(M), or -(O) gene could not be detected. The protein fingerprinting within the L. casei group proved that L. rhamnosus strains of clinical origin clustered together with probiotic strains. For safety evaluations resistance patterns of a broad range of strains are a useful criterion together with the exclusion of known resistance genes (like the vanA gene) and can be used for decision making on the safety of probiotics, both by authorization bodies and manufacturers.

Complete sequence of Enterococcus faecium pVEF3 and the detection of an omega-epsilon-zeta toxin-antitoxin module and an ABC transporter.

PubMed

Sletvold, H; Johnsen, P J; Hamre, I; Simonsen, G S; Sundsfjord, A; Nielsen, K M

2008-07-01

Glycopeptide resistant Enterococcus faecium (GREF) persists on Norwegian poultry farms despite the ban on the growth promoter avoparcin. The biological basis for long-term persistence of avoparcin resistance is not fully understood. This study presents the complete DNA sequence of the E. faecium R-plasmid pVEF3 and functional studies of some plasmid-encoded traits (a toxin-antitoxin (TA) system and an ABC transporter) that may be of importance for plasmid persistence. The pVEF3 (63.1 kbp), isolated from an E. faecium strain of poultry origin sampled in Norway in 1999, has 71 coding sequences including the vanA avoparcin/vancomycin resistance encoding gene cluster. pVEF3 encodes the TA system omega-epsilon-zeta, and plasmid stability tests and transcription analysis show that omega-epsilon-zeta is functional in Enterococcus faecalis OGIX, although with decreasing effect over time. The predicted ABC transporter was not found to confer reduced susceptibility to any of the 28 substances tested. The TA system identified in the pVEF-type plasmids may contribute to vanA plasmid persistence on Norwegian poultry farms. However, size and compositional heterogeneity among E. faecium vanA plasmids suggest that additional plasmid maintenance systems in combination with host specific factors and frequent horizontal gene transfer and rearrangement causes the observed plasmid composition and distribution patterns.

Narrow-Band Wide Field-of-View Filter Study

DTIC Science & Technology

1982-03-01

incidence for CdS and TeO2 ........ c. e .. ... . 17 6 Measurement of iso-index mode coupling response .............. ,.. 20 7 Temperature dependence...shift. The CdS sample has a FWHM of 4.2 A at the measurement wavelength. For comparison, a TeO2 crystal of similar bandwidth was measured. Figure 5 shows...is 330. The results for TeO2 , which can be simply related to that expected for quartz by the ratio of their refractive indices, indicate a FOV of only

Physical and antibacterial properties of açaí edible films formulated with thyme essential oil and apple skin polyphenols.

PubMed

Espitia, Paula J P; Avena-Bustillos, Roberto J; Du, Wen-Xian; Chiou, Bor-Sen; Williams, Tina G; Wood, Delilah; McHugh, Tara H; Soares, Nilda F F

2014-05-01

Thyme essential oil (TEO) and apple skin polyphenols (ASP) are natural compounds considered as generally recognized as safe by FDA, with biological effects against bacteria and fungi. This work aimed to evaluate physical and antimicrobial properties of açaí edible films formulated with TEO and ASP at 3% and 6% (w/w) individually or combined at 3% (w/w) each. Physical properties studied include mechanical resistance, water vapor permeability (WVP), color, and thermal resistance. Antimicrobial activity against Listeria monocytogenes was determined using the overlay diffusion test. Addition of ASP resulted in improved mechanical properties. TEO at 6% (w/w) resulted in increased elongation. ASP films had significant higher WVP than control film. ASP films were lighter and had more red color than other films. Incorporation of ASP resulted in improved film thermal stability, whereas TEO caused rapid thermal decomposition. Presence of clusters was observed on the surface of films. Addition of ASP resulted in a smoother surface, whereas addition of TEO led to the formation of crater-like pits on the film surface. Açaí edible film incorporated with 6% (w/w) TEO presented the highest antimicrobial activity. However, both antimicrobials are necessary in the açaí films in order to obtain edible films with suitable physical-mechanical properties. The results of the present study showed that TEO and ASP can be used to prepare açaí edible films with adequate physical-mechanical properties and antimicrobial activity for food applications by direct contact. Developed açaí edible films presented antimicrobial activity against L. monocytogenes and good physical-mechanical properties, showing the potential use of açaí edible films in food preservation. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Shelf life extension of lamb meat using thyme or oregano essential oils and modified atmosphere packaging.

PubMed

Karabagias, I; Badeka, A; Kontominas, M G

2011-05-01

The effect of thyme (TEO) and oregano (OEO) essential oils as well as modified atmosphere packaging (MAP) in extending the shelf life of fresh lamb meat stored at 4 °C was investigated. In a preliminary experiment TEO and OEO were used at concentrations 0.1 and 0.3% v/w while MAP tested included MAP1 (60% CO(2)/40% N(2)) and MAP2 (80% CO(2)/20% N(2)). Microbiological, physicochemical and sensory properties of lamb meat were monitored over a 20 day period. Sensory analysis showed that at the higher concentration both essential oils gave a strong objectionable odour and taste and were not further used. Of the two essential oils TEO was more effective as was MAP2 over MAP1 for lamb meat preservation. In a second experiment the combined effect of TEO (0.1%) and MAP2 (80/20) on shelf life extension of lamb meat was evaluated over a 25 day storage period. Microbial populations were reduced up to 2.8 log cfu/g on day 9 of storage with the most pronounced effect being achieved by the combination MAP2 plus TEO (0.1%). TBA values varied for all treatments and remained lower than 4 mg MDA/kg throughout storage. pH values varied between 6.4 and 6.0 during storage. Color parameters (L and b) increased with storage time while parameter (a) remained unaffected. Based primarily on sensory analysis (odour) but also on microbiological data, shelf life of lamb meat was 7 days for air packaged samples, 9-10 days for samples containing 0.1% of TEO and 21-22 days for MAP packaged samples containing 0.1% TEO. Copyright © 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.

Rich structural chemistry in new alkali metal yttrium tellurites: three-dimensional frameworks of NaYTe4O10, KY(TeO3)2, RbY(TeO3)2, and a novel variant of hexagonal tungsten bronze, CsYTe3O8.

PubMed

Kim, Youngkwon; Lee, Dong Woo; Ok, Kang Min

2015-01-05

Pure polycrystalline phases and single crystals of four new quaternary alkali metal yttrium tellurites, NaYTe4O10, KY(TeO3)2, RbY(TeO3)2, and CsYTe3O8, have been prepared by solid-state and hydrothermal reactions using A2CO3 (A = Na, K, Rb, and Cs), Y(NO3)3·6H2O, Y2O3, and TeO2 as starting reagents. X-ray diffraction analyses suggest that NaYTe4O10 exhibits a highly symmetric three-dimensional (3D) framework consisting of YO8 square antiprisms and chains of TeO4 polyhedra. Within the framework, six- (6-) and eight-membered ring (8-MR) channels are observed. KY(TeO3)2 and RbY(TeO3)2 are isostructural to each other and reveal another 3D framework with structures containing YO6 octahedra and TeO3 trigonal pyramids with 4-MR and 12-MR channels. CsYTe3O8 shows a hexagonal tungsten bronze (HTB)-like topology composed of hexagonal tungsten oxide-like layers of TeO4 polyhedra and YO6 octahedral linkers with 3-MR and 6-MR channels. Thermal analyses, elemental analyses, and spectroscopic characterizations, such as UV-vis diffuse reflectance and infrared spectra, are presented, as are local dipole moment calculations for the constituent asymmetric polyhedra TeO3 and TeO4.

Raman band intensities of tellurite glasses.

PubMed

Plotnichenko, V G; Sokolov, V O; Koltashev, V V; Dianov, E M; Grishin, I A; Churbanov, M F

2005-05-15

Raman spectra of TeO2-based glasses doped with WO3, ZnO, GeO2, TiO2, MoO3, and Sb2O3 are measured. The intensity of bands in the Raman spectra of MoO3-TeO2 and MoO3-WO3-TeO2 glasses is shown to be 80-95 times higher than that for silica glass. It is shown that these glasses can be considered as one of the most promising materials for Raman fiber amplifiers.

Novel Optical Processor for Phased Array Antenna.

DTIC Science & Technology

1992-10-20

parallel glass slide into the signal beam optical loop. The parallel glass acts like a variable phase shifter to the signal beam simulating phase drift...A list of possible designs are given as follows , _ _ Velocity fa (100dB/cm) Lumit Wavelength I M2I1 TeO2 Longi 4.2 /m/ns about 3 GHz 1.4 4m 34 Fast...subject to achievable acoustic frequency, the preferred materials are the slow shear wave in TeO2 , the fast shear wave in TeO2 or the shear waves in

Thermomechanical Properties of Sb2O3-TeO2-V2O5 Glassy Systems: Thermal Stability, Glass Forming Tendency and Vickers Hardness

NASA Astrophysics Data System (ADS)

Souri, Dariush; Torkashvand, Ziba

2017-04-01

Three-component 40TeO2-(60- x)V2O5- xSb2O3 glasses with 0 ≤ x ≤ 10 (in mol.%) were obtained by the rapid melt-quenching method. These glasses were studied with respect to some mechanical properties with the goal of obtaining information about their structure. The Vickers hardness test was employed to obtain Vickers micro-hardness ( H V) at two different loads, which was within the range of 13.187-17.557 GPa for a typical 0.1 HV (0.9807 N) load. In addition, theoretical micro-hardness ( H) was investigated and compared with experimental H V, showing the elevating trend with increase of Sb2O3 content, as for H V. Furthermore, differential scanning calorimetry (DSC) was employed within the range of 150-500°C at heating rates of φ = 3 K/min, 6 K/min, 9 K/min, 10 K/min, and 13 K/min. In this work, thermal stability ( T s = T cr - T x) and glass forming tendency ( K gl) were measured and reported for these glasses to determine the relationship between the chemical composition and the thermal stability, in order to interpret the structure of glass. Generally, from the ascertained outputs [analysis of mechanical data, titration study, the values of reduced fraction of vanadium ions ( C V) and oxygen molar volume ( V_{{O}}^{*} )], it was found that the micro-hardness had an increasing trend with increasing the Sb2O3 content. Among the studied glasses, the sample with x = 8 had a higher average micro-hardness value, the highest average thermal stability and glass forming tendency with respect to the other samples, which makes it a useful material (owning very good resistance against thermal attacks) for device manufacturing.

Understanding the influence of tellurium oxide in front Ag paste for contacting silicon solar cells with homogeneous high sheet resistance emitter

NASA Astrophysics Data System (ADS)

Ebong, Abasifreke; Bezawada, Nirupama; Batchu, Kartheek

2017-08-01

This paper investigates TeO2, one of the front Ag paste additives, to understand its role in low contact and gridline resistances for screen-printed Si solar cell. It is concluded that TeO2 aids the reduction of molten glass frit viscosity during contact co-firing. This in turn, leads to uniform flow of molten glass frit, both in the gridline bulk and interface of gridline and SiN x . Therefore, the uniform wetting and etching of SiN x and consequently larger contact area of metal to Si compared to its counterpart without TeO2. Hence, the current transport mechanism from Si to gridline can be said to be both direct and tunneling. The Raman spectra showed a blue shift in the phase of the TeO2 after contact co-firing in the gridline bulk confirming a crystalline γ-TeO2.

Spectroscopic properties and thermal stability of Er3+ -doped TeO2-B2O3-Nb2O5-ZnO glass for potential WDM amplifier.

PubMed

Xu, Tiefeng; Zhang, Xudong; Li, Guangpo; Dai, Shixun; Nie, Qiuhua; Shen, Xiang; Zhang, Xianghua

2007-06-01

A series of novel 70TeO2-(15-x)B2O3-xNb2O5-15ZnO-1wt.% Er2O3 (TBN x=0, 3, 6, 9, 12 and 15 mol%) tellurite glasses were prepared. The thermal stability, absorption spectra, emission spectra, and the lifetime of the (4)I(13/2) level of Er(3+) ions were measured and investigated. Three Judd-Ofelt intensity parameters Omega(t) (t=2, 4 and 6) (Omega(2)=(5.42-6.76)x10(-20)cm(2); Omega(4)=(1.37-1.73)x10(-20)cm(2); Omega(6)=(0.70-0.94)x10(-20)cm(2)) of Er(3+) ions were calculated by Judd-Ofelt theory. It is found that the Omega(6) first increases with the increase of Nb2O5 content from 0 to 6 mol% and then decreases, which is mainly affected by the number of non-bridging oxygen ions of the glass network. The high peak of stimulated emission cross-section (sigma(e)(peak)=(0.77-0.91)x10(-20)cm(2)) of Er(3+): (4)I(13/2)-->(4)I(15/2) transition were obtained according to McCumber theory and broad full width at half maximum (FWHM=65-73 nm) of the (4)I(13/2)-->(4)I(15/2) transition of Er(3+) ions were measured. The results indicate that these new TBN glasses can be used as a candidate host material for potential broadband optical amplifiers.

Single and combined effects of peppermint and thyme essential oils on productive performance, egg quality traits, and blood parameters of laying hens reared under cold stress condition (6.8 ± 3 °C)

NASA Astrophysics Data System (ADS)

Akbari, Mohsen; Torki, Mehran; Kaviani, Keyomars

2016-03-01

This study was conducted to evaluate the effects of adding peppermint essential oil (PEO), thyme essential oil (TEO), or their combination to diet on productive performance, egg quality traits, and blood parameters of laying hens reared under cold stress condition (6.8 ± 3 °C). Feed intake (FI), feed conversion ratio (FCR), egg weight (EW), egg production (EP), and egg mass (EM) were evaluated during the 56-day trial period using 120 Lohmann LSL-lite laying hens. Significant interactions between PEO and TEO on FCR, EP, and EM were observed ( P < 0.05). The EP and EM increased, whereas FCR decreased ( P < 0.05) in the hens fed the diets supplemented by the combined form of PEO and TEO compared to those fed the basal diet. Also, increased EW and FI were observed in the laying hens fed the diet added by PEO compared to the birds fed the basal diet. There were significant interactions between PEO and TEO on the serum level of cholesterol, shell thickness, and Hough unit of egg ( P < 0.05), so that serum content of cholesterol decreased, but egg shell thickness and Hough unit increased in the hens fed the diet supplemented by the combined form of PEO and TEO compared to those fed the basal diet. From the results of the present experiment, it can be concluded that diet supplementation by combined form of PEO and TEO could have beneficial effects on performance parameters of hens reared under cold stress condition.

Electrochromic Glasses.

DTIC Science & Technology

1980-07-31

this glass and that dipole-dipole correlations contribute to the "ferroelectric-like" character of this amorphous system. The TeO2 -W03 glasses can only...shows the dielectric constant and Fig. I(b) glass from pure TeO2 ot pure WO. In addition, glass the tan 8 of the WO glass as a function of temperature... glasses containing WO, in various glass forming nitworks of LifO-B1O0, Na:O-BzO,, and TeO2 were prepared from reagent grade oxides at 800 C - 9SO C in

Using remote sensing and GIS in addressing the future decisions regarding underused urban spaces; Hajj sites in Mecca as case study

NASA Astrophysics Data System (ADS)

Imam, Ayman; Roca, Josep

2017-10-01

The term Underused Urban Spaces (UUS) refers to spaces within urban areas that have become unused, or that are being used to a lesser degree than they could or should be such as former industrial zones, abandoned facilities or buildings and Expo or Olympic Games cities. The Islamic pilgrimage sites known as Hajj sites (HS) are considered form of the UUS concept as they are used lesser degree than they should be. However, the emergence of such spaces has therefore encouraged researchers, urban planner, social and local authorities to discuses about the appropriate decision regarding their future towards conversion or alternatively using those spaces in order to achieve positive social, economic and environmental benefits, according to Pagano and Bowman (2000), UUS can be a powerful tool for governments and investors to use during the urban growth (UG) of their cities. Since, remote sensing and GIS technologies are used recently to study and analyze the UG of cities; the main objective of this paper is to demonstrate the efficiency of those technologies in addressing the future decisions regarding the underused status of Hajj sites in relation to UG of the city of Mecca. Tow classified land cover maps of Mecca for two years (1998 and 2013), in addition to entropy index and multiple regression analyses were utilized in order to quantify the relationship between HS and Mecca UG. The results showed that the urban growth of Mecca has increased by approximately 56%, and almost 32% of that increased were around HS in on hand, and on the other hand the entropy and the regression analysis showed that there is 51% probability that the future growth to be also around HS. These findings will better addressing the future decisions regarding the underused status of HS, simultaneously revel that the use of RS and GIS was highly effective to be adopted within similar cases of UUS.

Study of Rare Nuclear Processes with CUORE

DOE PAGES

Alduino, C; Alfonso, K; III, FTA; ...

2018-03-30

TeO 2 bolometers have been used for many years to search for neutrinoless double beta decay in 130-Te. CUORE, a tonne-scale TeO 2 detector array, recently published the most sensitive limit on the half-life,more » $$T_{1/2}^{0\

Supporting Teachers for Race-, Class-, and Gender-Responsive Science Teaching

ERIC Educational Resources Information Center

Stapleton, Sarah Riggs

2015-01-01

In this response to Tang Wee Teo's article "Inside versus outside the science classroom: examining the positionality of two female science teachers at the boundaries of science education," I will extend the conversation around Teo's finding that the teachers in her study had difficulty translating their "politicized…

Study of Rare Nuclear Processes with CUORE

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

Alduino, C; Alfonso, K; III, FTA

TeO 2 bolometers have been used for many years to search for neutrinoless double beta decay in 130-Te. CUORE, a tonne-scale TeO 2 detector array, recently published the most sensitive limit on the half-life,more » $$T_{1/2}^{0\

Analysis of the world epidemiological situation among vancomycin-resistant Enterococcus faecium infections and the current situation in Poland

PubMed

Talaga-Ćwiertnia, Katarzyna; Bulanda, Małgorzata

2018-01-01

Vancomycin-resistant Enterococcus faecium (VREfm) strains have become an important hospital pathogen due to their rapid spread, high mortality rate associated with infections and limited therapeutic options. Vancomycin resistance is predominantly mediated by VanA or VanB phenotypes, which differ as regards maintaining sensitivity to teicoplanin in the VanB phenotype. The majority of VREfm cases in the United States, Europe, Korea, South America and Africa are currently caused by the VanA phenotype. However, the epidemics in Australia and Singapore are chiefly brought about by the VanB phenotype. The rate of VREfm isolate spread varies greatly. The greatest percentage of VREfm is now recorded in the USA, Ireland and Australia. Supervision of VRE is implemented to varying degrees. Therefore, the epidemiological situation in some countries is difficult to assess due to limited data or lack thereof.

Octadecylsilane hybrid silicas prepared by the sol-gel method: morphological and textural aspects.

PubMed

Brambilla, Rodrigo; Pires, Gilvan P; dos Santos, João H Z; Lacerda Miranda, Márcia S

2007-08-15

A series of octadecylsilane-modified silicas was prepared by the sol-gel method through the hydrolysis and cocondensation of tetraethylorthosilicate (TEOS) with octadecyltriethoxysilane (ODS). The ODS:TEOS ratio was varied between 0:100 and 100:0. The resulting carbon content was between 2.5 and 53.4%. In the case of pure ODS, the resulting silica presented 68.6% of C. Hybrid silicas were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and (29)Si nuclear magnetic resonance spectroscopy. Spheres of ca. 0.5-1.0 microm were obtained in the case of hydrolysis of pure TEOS. The combination of ODS:TEOS ratio yielded systems combining spherical and lamellar patterns zones. Monitoring the particle growth, it seems that spherical particles grow around lamellar zones, these latter concentrating the organosilicon moieties. The degree of cross-linking of ODS moieties was shown to be dependent on the ODS addition time and stirring speed.

Simulation of 100-300 GHz solid-state harmonic sources

NASA Technical Reports Server (NTRS)

Zybura, Michael F.; Jones, J. Robert; Jones, Stephen H.; Tait, Gregory B.

1995-01-01

Accurate and efficient simulations of the large-signal time-dependent characteristics of second-harmonic Transferred Electron Oscillators (TEO's) and Heterostructure Barrier Varactor (HBV) frequency triplers have been obtained. This is accomplished by using a novel and efficient harmonic-balance circuit analysis technique which facilitates the integration of physics-based hydrodynamic device simulators. The integrated hydrodynamic device/harmonic-balance circuit simulators allow TEO and HBV circuits to be co-designed from both a device and a circuit point of view. Comparisons have been made with published experimental data for both TEO's and HBV's. For TEO's, excellent correlation has been obtained at 140 GHz and 188 GHz in second-harmonic operation. Excellent correlation has also been obtained for HBV frequency triplers operating near 200 GHz. For HBV's, both a lumped quasi-static equivalent circuit model and the hydrodynamic device simulator have been linked to the harmonic-balance circuit simulator. This comparison illustrates the importance of representing active devices with physics-based numerical device models rather than analytical device models.

Effect of electrospun nanofibers on flexural properties of fiberglass composites

NASA Astrophysics Data System (ADS)

White, Fatima T.

In the present study, sintered electrospun TEOS nanofibers were interleaved in S2 fiberglass woven fabric layers, and composite panels were fabricated using the heated vacuum assisted resin transfer molding (H-VARTM) process. Cured panels were water jet cut to obtain the flexural test coupons. Flexural coupons were then tested using ASTM D7264 standard. The mechanical properties such as flexural strength, ultimate flexural failure strains, flexural modulus, and fiber volume fraction were measured. The S-2 fiberglass composite with the sintered TEOS electrospun nanofibers displayed lower flexural stiffness and strength as compared to the composites that were fabricated using S-2 fiberglass composite without the TEOS electrospun nanofibers. The present study also indicated that the composites fabricated with sintered TEOS electrospun nanofibers have larger failure strains as compared to the ones that were fabricated without the presence of electrospun nanofibers. The study indicates that the nanoengineered composites have better energy absorbing mechanism under flexural loading as compared to conventional fiberglass composites without presence of nanofibers.

Optical Processing for Adaptive Phased Array Radar.

DTIC Science & Technology

1981-06-01

cells. 24 Figure 2.5 TeO2 resporse (f and bandwidth) versus wavelengthc (X) of the input light used [29]. 25 Figure 2.6 AO cell frequency response (n...since BW - nV-. TeO2 offers an M = 13.1 versus MI = 1.0 for quartz. Other materials such as As 2Se 3 have higher M] 204 but are not available...3 6.il- F Strl( tlr( r th \\M eT 1s oh, 25 . Oes[ VE0 ’P J | +L I I I I 45 ]z C 20 30 40 50 𔃺 00 SIFREOUENCI IN MHz ’r Figure 2.5 TeO2 response

Vaporization thermodynamic studies by high-temperature mass spectrometry on some three-phase regions over the MnO-TeO2 binary line in the Mn-Te-O ternary system.

PubMed

Narasimhan, T S Lakshmi; Sai Baba, M; Viswanathan, R

2006-12-28

Knudsen effusion mass spectrometric measurements have been performed in the temperature range of 850-950 K over four three-phase mixtures, each phase mixture having at least one phase lying on the MnO-TeO2 binary line of the Mn-Te-O phase diagram, and the rest of the phases lying above this binary line. The three-phase mixtures investigated are Mn3O4 + MnO + Mn6Te5O16; Mn3O4 + Mn6Te5O16 + MnTeO3; Mn3O4 + Mn3TeO6 + MnTeO3; and Mn3TeO6 + MnTeO3 + Mn2Te3O8. The vapor pressures of the gaseous species TeO2, TeO, and Te2 over these three-phase mixtures were measured, and various heterogeneous solid-gas reactions were evaluated along with the homogeneous gas-phase reaction TeO2(g) + 0.5Te2(g) = 2 TeO(g). The enthalpy and Gibbs free energy of formation of the four ternary Mn-Te-O phases were deduced at T = 900 K. These values (in kJ.mol-1), along with the estimated uncertainties in them are Delta(f)H(o)m = 4150 +/- 19, 752 +/- 11, 1710 +/- 11, 1924 +/- 40, and Delta(f)G(o)m= 2835 +/- 28, 511 +/- 11, 1254 +/- 19, 1238 +/- 38, for Mn6Te5O16, MnTeO3, Mn3TeO6, and Mn2Te3O8, respectively. A thermochemical assessment was made to examine the conditions under which the ternary Mn-Te-O phases could be formed on a stainless steel clad of mixed-oxide-fueled (MO2; M = U + Pu) fast breeder nuclear reactors. The phase Mn3TeO6 could be formed when the fuel is even slightly hyperstoichiometric (O/M = 2.0002) and the phase Mn6Te5O16 could also be formed when O/M = 2.0004. The threshold tellurium potential for the formation of Mn3TeO6 is higher than that for MnTe0.80 and CrTe1.10, but is comparable to that for MoTe1.10, and even lower than that for FeTe0.81 or NiTe0.63.

The Effect of Surfactant and Compatibilizer on Inorganic Loading and Properties of PPO-based EPMM Membranes

NASA Astrophysics Data System (ADS)

Bissadi, Golnaz

Hybrid membranes represent a promising alternative to the limitations of organic and inorganic materials for high productivity and selectivity gas separation membranes. In this study, the previously developed concept of emulsion-polymerized mixed matrix (EPMM) membranes was further advanced by investigating the effects of surfactant and compatibilizer on inorganic loading in poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based EPMM membranes, in which inorganic part of the membranes originated from tetraethylorthosilicate (TEOS). The polymerization of TEOS, which consists of hydrolysis of TEOS and condensation of the hydrolyzed TEOS, was carried out as (i) one- and (ii) two-step processes. In the one-step process, the hydrolysis and condensation take place in the same environment of a weak acid provided by the aqueous solution of aluminum hydroxonitrate and sodium carbonate. In the two-step process, the hydrolysis takes place in the environment of a strong acid (solution of hydrochloric acid), whereas the condensation takes place in weak base environment obtained by adding excess of the ammonium hydroxide solution to the acidic solution of the hydrolyzed TEOS. For both one- and two-step processes, the emulsion polymerization of TEOS was carried out in two types of emulsions made of (i) pure trichloroethylene (TCE) solvent, and (ii) 10 w/v% solution of PPO in TCE, using different combinations of the compatibilizer (ethanol) and the surfactant (n-octanol). The experiments with pure TCE, which are referred to as a gravimetric powder method (GPM) allowed assessing the effect of different experimental parameters on the conversion of TEOS. The GPM tests also provided a guide for the synthesis of casting emulsions containing PPO, from which the EPMM membranes were prepared using a spin coating technique. The synthesized EPMM membranes were characterized using 29Si nuclear magnetic resonance (29Si NMR), differential scanning calorimetry (DSC), inductively coupled plasma mass

Hydrophilicity, photocatalytic activity and stability of tetraethyl orthosilicate modified TiO2 film on glazed ceramic surface

NASA Astrophysics Data System (ADS)

Zhang, Peng; Tian, Jie; Xu, Ruifen; Ma, Guojun

2013-02-01

A new, simple, and low-cost method has been developed to enhance the surface properties of TiO2 film. Degussa P25-TiO2 nanoparticles were modified by tetraethyl orthosilicate (TEOS) on glazed ceramic tiles. Effects of tetraethyl orthosilicate modification on microstructure, crystal structure, hydrophilicity, photocatalytic activity and stability of the film were investigated. The obtained results showed that P25-TiO2/TEOS particles exhibited better dispersion, higher surface area, bigger surface roughness and smaller particle size comparing to pure P25-TiO2 particles, which resulted in better hydrophilicity after 10 days in a dark place and higher photocatalytic activity under visible light irradiation. 68% of Rhodamine B was degraded by P25-TiO2/TEOS film in 25 h with the light intensity of 5000 ± 500 lx, and degradation rate reached to 82% with the light intensity of 10,000 ± 1000 lx. Furthermore, two fundamentally different systems, in which the films recycle for repetitive degradation after soaked in dye solution and for discoloration after depositing dye on the surfaces, respectively, were measured to confirm that P25-TiO2/TEOS film showed excellently stable performances. Therefore the P25-TiO2/TEOS film we obtained has good washing resistance and would be a promising candidate for practical applications.

Faster and economical screening for vancomycin-resistant enterococci by sequential use of chromogenic agar and real-time polymerase chain reaction.

PubMed

Tan, Thean Yen; Jiang, Boran; Ng, Lily Siew Yong

2017-08-01

Screening for vancomycin-resistant enterococci (VRE) by culture takes days to generate results, while polymerase chain reaction (PCR) testing directly from clinical specimens lacks specificity. The aims of this study were to develop a real-time PCR to detect and identify Enterococcus faecium, Enterococcus faecalis, and vanA and vanB genes, and to evaluate the impact of this PCR on test-reporting times when performing it directly from suspect VRE isolates present on screening chromogenic media. The tetraplex PCR primers were designed to amplify E. faecium, E. faecalis, and vanA and vanB genes, with melt-curve analysis of PCR products. Following analytical and clinical validation of the molecular assay, PCR testing was performed for target colonies present on VRE chromogenic media. PCR results were evaluated against conventional phenotypic identification and susceptibility testing, with the time to result being monitored for both modalities. A total of 519 colonies from clinical specimens were tested concurrently by real-time PCR and phenotypic methods. In all, 223 isolates were identified with phenotypic vancomycin resistance (vanA, n = 108; vanB, n = 105; non-vanA/vanB = 10), with complete agreement between PCR and phenotypic testing for vancomycin-resistant E. faecium and E. faecalis. The majority (88.6%) of PCR results were reported, on average, 24.8 hours earlier than those of phenotypic testing, with 68% reduction in total costs. The use of culture on selective media, followed by direct colony PCR confirmation allows faster and economical VRE screening. Copyright © 2015. Published by Elsevier B.V.

Charge trapping phenomena of tetraethylorthosilicate thin film containing Si nanocrystals synthesized by solid-state reaction.

PubMed

Lau, H W; Tan, O K; Liu, Y; Trigg, D A; Chen, T P

2006-08-28

In this work, we report on the fabrication of tetraethylorthosilicate (TEOS) thin dielectric film containing silicon nanocrystals (Si nc), synthesized by solid-state reaction, in a capacitor structure. A metal-insulator-semi-conductor (MIS) capacitor, with 28 nm thick Si nc in a TEOS thin film, has been fabricated. For this MIS, both electron and hole trapping in the Si nc are possible, depending on the polarity of the bias voltage. A V(FB) shift greater than 1 V can be experienced by a bias voltage of 16 V applied to the metal electrode for 1 s. Though there is no top control oxide, the discharge time for 10% of charges can be up to 4480 s when it is biased at 16 V for 1 s. It is further demonstrated that charging and discharging mechanisms are due to the Si nc rather than the TEOS oxide defects. This form of Si nc in a TEOS thin film capacitor provides the possibility of memory applications at low cost.

Optical and spectroscopic investigation on Calcium Borotellurite glass system

NASA Astrophysics Data System (ADS)

Paz, E. C.; Lodi, T. A.; Gomes, B. R. A.; Melo, G. H. A.; Pedrochi, F.; Steimacher, A.

2016-05-01

In this work, the glass formation in Calcium Borotellurite (CBTx) system and their optical properties were studied. Six glass samples were prepared by melt-quenching technique and the samples obtained are transparent, lightly yellowish, without any visible crystallites. The results showed that TeO2 addition increases the density, the electronic polarizability and, consequently, the refractive index. The increase of electronic polarizability and optical basicity suggest that TeO2 addition increases the non-bridging oxygen (NBO) concentration. The increase of TeO2 shifts the band edge to longer wavelength owing to increase in non-bridging oxygen ions, resulting in a linear decrease of optical energy gap. The addition of TeO2 increases the temperature coefficient of the optical path length (dS/dT) in room temperature, which are comparable to phosphate and lower than Low Silica Calcium Alumino Silicate (LSCAS) glasses. The values of dS/dT present an increase as a function of temperature for all the samples measured. The results suggest that CBTx is a good candidate for rare-earth doping and several optical applications.

Fouling-release coatings prepared from alpha,omega-dihydroxypoly(dimethylsiloxane) cross-linked with (heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane.

PubMed

Berglin, Mattias; Wynne, Kenneth J; Gatenholm, Paul

2003-01-15

Surface properties of pristine and water-aged polymeric films made of alpha,omega-dihydroxypoly(dimethylsiloxane) (PDMS) cross-linked with (heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane (FTEOS17) or tetraethoxysilane (TEOS) were investigated. The FTEOS17-cured coatings showed stable advancing and receding contact angles over a period of 3 months of water exposure, compared to a 70 degrees decrease in receding contact angle for the TEOS-cured coatings. After immersion in water, hydroxyl groups were detected on the TEOS-cured coatings with attenuated total reflection infrared spectroscopy (ATR-FT/IR). Tapping-mode atomic force microscopy (TM-AFM) on pristine FTEOS17-cured coatings showed surfaces topologies ranging from smooth and featureless to topologically complex, depending on FTEOS17 concentration. The fluorinated coatings showed a stable surface morphology after water immersion, which we believe is due to the formation of a fluorinated siliceous phase that prevented the surface reconstruction, water penetration, and hydrolysis. The smooth pristine TEOS-cured coatings showed an increased roughness with cracks and erosion pits present on the surface after water immersion.

Adsorption enhancement of elemental mercury onto sulphur-functionalized silica gel adsorbents.

PubMed

Johari, Khairiraihanna; Saman, Norasikin; Mat, Hanapi

2014-01-01

In this study, elemental mercury (EM) adsorbents were synthesized using tetraethyl orthosilicate (TEOS) and 3-mercaptopropyl trimethoxysilane as silica precursors. The synthesized silica gel (SG)-TEOS was further functionalized through impregnation with elemental sulphur and carbon disulphide (CS2). The SG adsorbents were then characterized by using scanning electron microscope, Fourier transform infra-red spectrophotometer, nitrogen adsorption/desorption, and energy-dispersive X-ray diffractometer. The EM adsorption of the SG adsorbents was determined using fabricated fixed-bed adsorber. The EM adsorption results showed that the sulphur-functionalized SG adsorbents had a greater Hgo breakthrough adsorption capacity, confirming that the presence of sulphur in silica matrices can improve Hgo adsorption performance due to their high affinity towards mercury. The highest Hgo adsorption capacity was observed for SG-TEOS(CS2) (82.62 microg/g), which was approximately 2.9 times higher than SG-TEOS (28.47 microg/g). The rate of Hgo adsorption was observed higher for sulphur-impregnated adsorbents, and decreased with the increase in the bed temperatures.

Enhanced 3  μm luminescence properties based on effective energy transfer Yb3+ : 2F5/2→Dy3+ : 6H5/2 in fluoaluminate glass modified by TeO2.

PubMed

Qi, Fangwei; Huang, Feifei; Wang, Tao; Tian, Ying; Lei, Ruoshan; Ye, Renguang; Zhang, Junjie; Zhang, Long; Xu, Shiqing

2017-11-01

Enhanced 3 μm luminescence of Dy 3+ based on the effective process of Yb 3+ :F 5/2 2→Dy 3+ :H 5/2 6 with a higher energy transfer coefficient of 7.36×10 -39   cm 6 /s in fluoaluminate glass modified by TeO 2 was obtained. The energy transfer efficiency from Yb 3+ to Dy 3+ in Dy 3+ /Yb 3+ codoped glass was as high as 80%, indicating the effective energy transfer of Yb 3+ . The higher temperature of the glass transition (T g ) and larger characteristic temperatures (ΔT,K gl ) revealed better thermal properties of the prepared glasses compared with the traditional fluoaluminate glasses, which is of great benefit to fiber drawing. The lower hydroxyl content (15.7 ppm) indicated better fluorescence properties of the glass. It was noted that the longer lifetime of 572 μs and higher emission cross section of 5.22×10 -21   cm 2 along with the bandwidth of 245 nm around 3 μm proved potential applications in mid-IR laser materials of the present glass.

Atomistic simulations of TeO₂-based glasses: interatomic potentials and molecular dynamics.

PubMed

Gulenko, Anastasia; Masson, Olivier; Berghout, Abid; Hamani, David; Thomas, Philippe

2014-07-21

In this work we present for the first time empirical interatomic potentials that are able to reproduce TeO2-based systems. Using these potentials in classical molecular dynamics simulations, we obtained first results for the pure TeO2 glass structure model. The calculated pair distribution function is in good agreement with the experimental one, which indicates a realistic glass structure model. We investigated the short- and medium-range TeO2 glass structures. The local environment of the Te atom strongly varies, so that the glass structure model has a broad Q polyhedral distribution. The glass network is described as weakly connected with a large number of terminal oxygen atoms.

Energy Transfer between Post-Transition Elements & Rare Earths in Oxide & Chalcogenide Glasses.

DTIC Science & Technology

1979-08-27

Caird [13]. A calculation of reduced matrix elements of Pr3 in 20 Na O • 80 TeO2 glass [14] showed that they differ slightly from data of ref. [121... glasses Transition (lass 35 ZnO 65 TeO2 20 Na2 O 80 TeO 2 fX 106 fX 106 l.,eas 3a, a) Ia’l. faI f.me.s f al f+ I fal 3 H4 - 3 H6 1.56 1.65 1.12...Rare-Earth Doped Glasses 20. jIST HAEV CCnFn~m ,i cn,on ra e sideit If c."*Ar’ -- ~ 14-r by t?-h.c .: r Intensity parameters, radiative transition

Archaeological Sites Inventory of the High Priority Portions of Training Areas 1, 2, 3, 4, 5, 6, 11, 13, and H of the Pinon Canyon Maneuver Site, Las Animas County, Colorado

DTIC Science & Technology

2007-03-18

is abundant over the PCMS, but within our 2001 project area locations, only intermittent arroyos and seasonal springs in the Timpas, Luning , Van...a hilltop above an unnamed tributary of Luning Arroyo. Four chert artifacts were identified, including two utilized/retouched flakes, a simple flake

A Cross-Cultural Validity of the E-Learning Acceptance Measure (ElAM) in Lebanon and England: A Confirmatory Factor Analysis

ERIC Educational Resources Information Center

Tarhini, Ali; Teo, Timothy; Tarhini, Takwa

2016-01-01

Despite the prevalence and significance of e-learning in education, there is a dearth of published instruments for educational researchers and practitioners that measure users' acceptance of e-learning. To meet this need, Teo (2010) developed the E-learning Acceptance Measure (ElAM). The main objective of this paper is to validate the ElAM (Teo,…

Electrical studies of D%AgI-(100-D)%[0.667Ag2O- 0.333{(0.4)B2O3-(0.6)TeO2}] fast ion conducting glasses

NASA Astrophysics Data System (ADS)

Kumar, E. Ramesh; Nageswar Rao, P.; Appa Rao, B.

2016-09-01

Super ion conducting glasses of composition D%AgI-(100-D)%[MAg2O-F{(F1)B2O3- (F2)TeO2}]; D=10.0 to 60.0 in steps of 10.0 for a fixed values of F1 (0.4), F2 (0.6) which are glass network formers, fixed values of modifier M(0.667), F (0.333) and D is dopant salt which was varied. These glasses were prepared by melt quenching technique. XRD spectra taken for all the samples. Electrical characterization was done in terms of AC and DC conductivities. DC and AC conductivities at room temperature increased from 10-5 to 10-1 scm-1 and DC activation energy (Edc) found to decrease from 0.36 to 0.19eV with increase in D% ratio. Measurements are performed over the frequency range 1 kHz to 3 MHz at different temperatures. From the impedance spectroscopy real and imaginary parts of impedances (Z', Z"), conductivities were calculated and plotted, and equivalent R-C circuit parameters were obtained from Cole-Cole plots. With the increase in D%, AC conductivity is observed to increase whereas the AC activation energy (Eac) is observed to decrease from 0.23 to 0.14 eV. The quantitative analysis of these results indicates that the electrical conductivity of silver borate glasses is enhanced with increase in D% ratio. Based on conductivity values these glasses are ionic conductors, in which conduction is by hopping mechanism. An attempt is made to understand the charge transportation process.

Structural characterization of tellurite glasses doped with transition metal oxides using Raman spectra and ab initio calculations.

PubMed

Mohamed, Tarek A; Shaltout, I; Al Yahyaei, K M

2006-05-01

Systems of iron tellurite glasses were prepared by melt quenching with compositions of [85%TeO2+5%Fe2O3+10%TMO], where transition metal oxides (TMO) are TiO2, V2O5, MnO, CoO, NiO and CuO. Furthermore, the main structural units of these samples have been characterized by means of Raman spectra (150-1200 cm(-1)) as well as wavenumber predictions by means of Gaussian 98 ab initio calculations for the proposed site symmetries of TeO4(4-) triagonal bipyramid (C2v) and Te2O7(6-) bridged tetrahedra (Cs and C1). Aided by normal coordinate analysis, calculated vibrational frequencies, Raman scattering activities, force constants in internal coordinates and potential energy distributions (PEDs), revised vibrational assignments for the fundamental modes have been proposed. The main structural features are correlated to the dominant units of triagonal bipyramid (tbp) or bridged tetrahedral (TeO3+1 binds to TeO3 through TeOTe bridge; corner sharing). Moreover, the Raman spectra of the investigated tellurites reflect a structural change from tbp (coordination number is four) to triagonal pyramidal (coordination number is three).

Vancomycin-Resistant Enterococci and Bacterial Community Structure following a Sewage Spill into an Aquatic Environment

PubMed Central

Young, Suzanne; Nayak, Bina; Sun, Shan; Badgley, Brian D.; Rohr, Jason R.

2016-01-01

ABSTRACT Sewage spills can release antibiotic-resistant bacteria into surface waters, contributing to environmental reservoirs and potentially impacting human health. Vancomycin-resistant enterococci (VRE) are nosocomial pathogens that have been detected in environmental habitats, including soil, water, and beach sands, as well as wildlife feces. However, VRE harboring vanA genes that confer high-level resistance have infrequently been found outside clinical settings in the United States. This study found culturable Enterococcus faecium harboring the vanA gene in water and sediment for up to 3 days after a sewage spill, and the quantitative PCR (qPCR) signal for vanA persisted for an additional week. Culturable levels of enterococci in water exceeded recreational water guidelines for 2 weeks following the spill, declining about five orders of magnitude in sediments and two orders of magnitude in the water column over 6 weeks. Analysis of bacterial taxa via 16S rRNA gene sequencing showed changes in community structure through time following the sewage spill in sediment and water. The spread of opportunistic pathogens harboring high-level vancomycin resistance genes beyond hospitals and into the broader community and associated habitats is a potential threat to public health, requiring further studies that examine the persistence, occurrence, and survival of VRE in different environmental matrices. IMPORTANCE Vancomycin-resistant enterococci (VRE) are harmful bacteria that are resistant to the powerful antibiotic vancomycin, which is used as a last resort against many infections. This study followed the release of VRE in a major sewage spill and their persistence over time. Such events can act as a means of spreading vancomycin-resistant bacteria in the environment, which can eventually impact human health. PMID:27422829

Incipient fault feature extraction of rolling bearings based on the MVMD and Teager energy operator.

PubMed

Ma, Jun; Wu, Jiande; Wang, Xiaodong

2018-06-04

Aiming at the problems that the incipient fault of rolling bearings is difficult to recognize and the number of intrinsic mode functions (IMFs) decomposed by variational mode decomposition (VMD) must be set in advance and can not be adaptively selected, taking full advantages of the adaptive segmentation of scale spectrum and Teager energy operator (TEO) demodulation, a new method for early fault feature extraction of rolling bearings based on the modified VMD and Teager energy operator (MVMD-TEO) is proposed. Firstly, the vibration signal of rolling bearings is analyzed by adaptive scale space spectrum segmentation to obtain the spectrum segmentation support boundary, and then the number K of IMFs decomposed by VMD is adaptively determined. Secondly, the original vibration signal is adaptively decomposed into K IMFs, and the effective IMF components are extracted based on the correlation coefficient criterion. Finally, the Teager energy spectrum of the reconstructed signal of the effective IMF components is calculated by the TEO, and then the early fault features of rolling bearings are extracted to realize the fault identification and location. Comparative experiments of the proposed method and the existing fault feature extraction method based on Local Mean Decomposition and Teager energy operator (LMD-TEO) have been implemented using experimental data-sets and a measured data-set. The results of comparative experiments in three application cases show that the presented method can achieve a fairly or slightly better performance than LMD-TEO method, and the validity and feasibility of the proposed method are proved. Copyright © 2018. Published by Elsevier Ltd.

Nanoparticle-neural stem cells for targeted ovarian cancer treatment: optimization of silica nanoparticles for efficient drug loading

NASA Astrophysics Data System (ADS)

Patel, Z.; Berlin, J.; Abidi, W.

2018-02-01

One of the drugs used to treat ovarian cancer is cisplatin. However, cisplatin kills normal surrounding tissue in addition to cancer cells. To improve tumor targeting efficiency, our lab uses neural stem cells (NSCs), which migrate directly to ovarian tumors. If free cisplatin is loaded into NSCs for targeted drug delivery, it will kill the NSCs. To prevent the drug cisplatin from killing both the NSCs and normal surrounding tissue, our lab synthesizes silica nanoparticles (SiNPs) that act as a protective carrier. The big picture here is to maximize efficiency of tumor targeting using NSCs and minimize toxicity to these NSCs using SiNPs. The goal of this project is to optimize the stability of SiNPs, which is important for efficient drug loading. To do this, the concentration of tetraethyl orthosilicate (TEOS), one of the main components of SiNPs, was varied. We hypothesized that more TEOS equates to more stable SiNPs because TEOS contributes carbon to SiNPs, and thus a tightly-packed chemical structure results in a stable particle. Then, the stability of the SiNPs were checked in cell media and phosphate buffered saline (PBS). Lastly, the SiNPs were analyzed for their porosity using the transmission electron microscope (TEM). TEM imaging showed white spots in the 200-800 μL TEOS batches and no white spots in the 1000-1800 μL TEOS batches. The white spots were pores, which indicate instability. We concluded that the ultimate factor that determines the stability of SiNPs (100 nm) is the concentration of organic substance.

Radar Imaging for Moving Targets

DTIC Science & Technology

2009-06-01

MOVING TARGETS by Teo Beng Koon William June 2009 Thesis Advisor: Brett H. Borden Second Reader: Donald L. Walters THIS PAGE...Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project...TITLE AND SUBTITLE Radar Imaging for Moving Targets 6. AUTHOR(S) Teo Beng Koon William 5. FUNDING NUMBERS 7. PERFORMING ORGANIZATION NAME(S

Performance Evaluation of a Routing Protocol in Wireless Sensor Network

DTIC Science & Technology

2005-12-01

OF A ROUTING PROTOCOL IN WIRELESS SENSOR NETWORKS by Cheng Kiat Amos, Teo December 2005 Thesis Advisors: Gurminder Singh John C...Evaluation of a Routing Protocol in Wireless Sensor Network 6. AUTHOR(S) Cheng Kiat Amos, Teo 5. FUNDING NUMBERS 7. PERFORMING ORGANIZATION NAME(S...need to be strategically positioned and have topologies engineered. As such, recent research into wireless sensor networks has attracted great

Apatite-forming ability and mechanical properties of PTMO-modified CaO-SiO2-TiO2 hybrids derived from sol-gel processing.

PubMed

Miyata, Noboru; Fuke, Ken-ichi; Chen, Qi; Kawashita, Masakazu; Kokubo, Tadashi; Nakamura, Takashi

2004-01-01

Hydrolysis and polycondensation of triethoxysilane end-capped Poly (tetramethylene oxide) (Si-PTMO), tetraethoxysilane (TEOS), tetraisopropyltitanate (TiPT) and calcium nitrate (Ca(NO(3))(2)) gave transparent monolithics of PTMO-modified CaO-SiO(2)-TiO(2) hybrids. The samples with (TiPT)/(TEOS+TiPT) molar ratios from 0 to 0.20 under constant ratio of (Si-PTMO)/(TEOS+TiPT) of 2/3 in weight were prepared. It was found that the incorporation of TiO(2) component into a PTMO-CaO-SiO(2) hybrid results in an increase in the apatite-forming ability in a simulated body fluid: the hybrids with (TiPT)/(TEOS+TiPT) of 0.10 and 0.20 in mol formed an apatite on their surfaces within only 0.5 day. It seemed that, within the range of compositions studied, the TiO(2) content little affects the overall mechanical properties: Young's modulus were 52-55MPa, tensile strength, 7-9MPa, and strain at failure, about 30%. Thus, the organic-inorganic hybrids exhibiting both fairly high apatite-forming ability and high capability for deformation were obtained. These hybrid materials may be useful as new kind of bioactive bone-repairing materials.

Biosilica-loaded poly(ϵ-caprolactone) nanofibers mats provide a morphogenetically active surface scaffold for the growth and mineralization of the osteoclast-related SaOS-2 cells.

PubMed

Müller, Werner E G; Tolba, Emad; Schröder, Heinz C; Diehl-Seifert, Bärbel; Link, Thorben; Wang, Xiaohong

2014-10-01

Bioprinting/3D cell printing procedures for the preparation of scaffolds/implants have the potential to revolutionize regenerative medicine. Besides biocompatibility and biodegradability, the hardness of the scaffold material is of critical importance to allow sufficient mechanical protection and, to the same extent, allow migration, cell-cell, and cell-substrate contact formation of the matrix-embedded cells. In the present study, we present a strategy to encase a bioprinted, cell-containing, and soft scaffold with an electrospun mat. The electrospun poly(ϵ-caprolactone) (PCL) nanofibers mats, containing tetraethyl orthosilicate (TEOS), were subsequently incubated with silicatein. Silicatein synthesizes polymeric biosilica by polycondensation of ortho-silicate that is formed from prehydrolyzed TEOS. Biosilica provides a morphogenetically active matrix for the growth and mineralization of osteoblast-related SaOS-2 cells in vitro. Analysis of the microstructure of the 300-700 nm thick PCL/TEOS nanofibers, incubated with silicatein and prehydrolyzed TEOS, displayed biosilica deposits on the mats formed by the nanofibers. We conclude and propose that electrospun PCL nanofibers mats, coated with biosilica, may represent a morphogenetically active and protective cover for bioprinted cell/tissue-like units with a suitable mechanical stability, even if the cells are embedded in a softer matrix. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of polarizable lone pair cations on the second-harmonic generation (SHG) properties of noncentrosymmetric (NCS) Bi(2-x)Y(x)TeO₅ (x = 0-0.2).

PubMed

Jo, Hongil; Kim, Yeong Hun; Lee, Dong Woo; Ok, Kang Min

2014-08-14

Y(3+)-doped noncentrosymmetric (NCS) bismuth tellurite materials, Bi(2-x)Y(x)TeO5 (x = 0, 0.1, and 0.2), have been synthesized through standard solid-state reactions and structurally characterized by powder neutron diffraction. The reported NCS materials crystallize in the orthorhombic space group Abm2 (no. 39), and exhibit pseudo-three-dimensional frameworks that are composed of BiO3, BiO5, and TeO3 polyhedra. Detailed diffraction studies show that the cell volume of Bi(2-x)Y(x)TeO5 decreases with an increasing amount of Y(3+)on the Bi(3+) sites. However, no ordering between Bi(3+) and Y(3+) was observed in the Bi(2-x)Y(x)TeO5. Powder second-harmonic generation (SHG) measurements, using 1064 nm radiation, reveal that Bi2TeO5, Bi(1.9)Y(0.1)TeO5, and Bi(1.8)Y(0.2)TeO5 exhibit SHG efficiencies of approximately 300, 200, and 60 times that of α-SiO2, respectively. The reduction in SHG for Y(3+)-doped materials is consistent with the lack of net moment originating from polyhedra with a polarizable Bi(3+) cation.

Thymus vulgaris essential oil and thymol against Alternaria alternata (Fr.) Keissler: effects on growth, viability, early infection and cellular mode of action.

PubMed

Perina, Fabiano J; Amaral, Douglas C; Fernandes, Rafael S; Labory, Claudia Rg; Teixeira, Glauco A; Alves, Eduardo

2015-10-01

In initial assays, Thymus vulgaris essential oil (TEO) has demonstrated activity against several plant-pathogenic fungi and has reduced the fungal diseases to levels comparable with commercial fungicides. Thus, the goal of this work was to identify the mode of action in fungi of TEO and its major compound thymol (TOH) at the cellular level using an ultrastructure approach. TEO from leaves and TOH had minimum inhibitory concentrations (MICs) of 500 and 250 µg mL(-1) respectively against A. alternata; under the same conditions, MIC for a commercial fungicide was 1250 µg mL(-1) . Ultrastructure analysis showed that TOH phenolic substance prevented fungal growth, reduced fungal viability and prevented the penetration in fruits by a cell wall/plasma membrane interference mode of action with organelles targeted for destruction in the cytoplasm. Such mode of action differs from protective and preventive-curative commercial fungicides used as pattern control. These findings suggest that TOH was responsible for the antifungal activity of TEO. Therefore, both the essential oil and its major substance have potential for use in the development of new phenolic structures and analogues to control Alternaria brown spot disease caused by Alternaria alternata. © 2014 Society of Chemical Industry.

Impact of Sweet Potato Starch-Based Nanocomposite Films Activated With Thyme Essential Oil on the Shelf-Life of Baby Spinach Leaves

PubMed Central

Issa, Aseel; Ibrahim, Salam A.; Tahergorabi, Reza

2017-01-01

Salmonella Typhimurium (S. Typhi) and Escherichia coli (E. coli) have been responsible for an increasing number of outbreaks linked to fresh produce, such as baby spinach leaves, in the last two decades. More recently, antimicrobial biodegradable packaging systems have been attracting much attention in the food packaging industry as eco-friendly alternatives to conventional plastic packaging. The objective of this study was to evaluate the effect of antibacterial nanocomposite films on inoculated spinach leaves and on the sensory properties of these leaves during eight days of refrigerated storage. In this study, an antibacterial film comprised of sweet potato starch (SPS), montmorillonite (MMT) nanoclays and thyme essential oil (TEO) as a natural antimicrobial agent was developed. Our results showed that the incorporation of TEO in the film significantly (p < 0.05) reduced the population of E. coli and S. Typhi on fresh baby spinach leaves to below detectable levels within five days, whereas the control samples without essential oil maintained approximately 4.5 Log colony forming unit (CFU)/g. The sensory scores for spinach samples wrapped in films containing TEO were higher than those of the control. This study thus suggests that TEO has the potential to be directly incorporated into a SPS film to prepare antimicrobial nanocomposite films for food packaging applications. PMID:28587199

Mechanistic study of atomic layer deposition of Al{sub x}Si{sub y}O thin film via in-situ FTIR spectroscopy

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

Cho, Jea; Kim, Taeseung; Seegmiller, Trevor

2015-09-15

A study of surface reaction mechanism on atomic layer deposition (ALD) of aluminum silicate (Al{sub x}Si{sub y}O) was conducted with trimethylaluminum (TMA) and tetraethoxysilane (TEOS) as precursors and H{sub 2}O as the oxidant. In-situ Fourier transform infrared spectroscopy (FTIR) was utilized to elucidate the underlying surface mechanism that enables the deposition of Al{sub x}Si{sub y}O by ALD. In-situ FTIR study revealed that ineffective hydroxylation of the surface ethoxy (–OCH{sub 2}CH{sub 3}) groups prohibits ALD of SiO{sub 2} by TEOS/H{sub 2}O. In contrast, effective desorption of the surface ethoxy group was observed in TEOS/H{sub 2}O/TMA/H{sub 2}O chemistry. The presence of Al-OH*more » group in vicinity of partially hydroxylated ethoxy (–OCH{sub 2}CH{sub 3}) group was found to propagate disproportionation reaction, which results in ALD of Al{sub x}Si{sub y}O. The maximum thickness from incorporation of SiO{sub x} from alternating exposures of TEOS/H{sub 2}O chemistry in Al{sub x}Si{sub y}O was found to be ∼2 Å, confirmed by high resolution transmission electron microscopy measurements.« less

Reddish-orange, neutral and warm white emissions in Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses

NASA Astrophysics Data System (ADS)

Rodríguez-Carvajal, David A.; Meza-Rocha, A. N.; Caldiño, U.; Lozada-Morales, R.; Álvarez, E.; Zayas, Ma. E.

2016-11-01

Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses were prepared using the melt-quenching process and analyzed by X-diffraction, Raman spectroscopy, excitation and emission spectra, and emission decay time profiles. The lack of X ray diffraction peaks revealed that all samples are amorphous. Vibrational modes associated with Tesbnd Osbnd Te and Gesbnd Osbnd Ge related bonds and molecular oxygen were detected by Raman spectroscopy. The luminescence characteristics were studied upon excitations that correspond with the emission of InGaN (370-420 nm) based LEDs. The Eu3+ singly doped glass displayed reddish-orange global emission, with x = 0.601 and y = 0.349 CIE1931 chromaticity coordinates, upon 393 nm excitation. Neutral emission with x = 0.373 and y = 0.412 CIE1931 chromaticity coordinates and correlated color temperature (CCT) of 4400 K, was achieved in the Dy3+ singly doped glass excited at 388 nm. The Dy3+/Eu3+ co-doped glass exhibited warm, neutral and soft warm white emissions with CCT values of 3435, 4153 and 2740 K, under excitations at 382, 388 and 393 nm, respectively, depending mainly on the Dy3+ and Eu3+ relative excitation. The Dy3+ excitation bands observed in the Dy3+/Eu3+ glass by monitoring the 611 nm Eu3+ emission, suggest that Dy3+ → Eu3+ energy transfer takes place, despite the fact that the Dy3+ emission decays in the Dy3+ and Dy3+/Eu3+ doped glass, remain without changes. The shortening of Eu3+ decay in presence of Dy3+ was attributed to an Eu3+ → Dy3+ non-radiative energy transfer process, which according with the Inokuti-Hirayama model might be dominated through an electric quadrupole-quadrupole interaction, with efficiency and probability of 5.5% and 51.6 s-1, respectively.

An Automated System for Accurately Tracking and Measuring Multiple Targets in Six Dimensions

DTIC Science & Technology

2001-08-01

diffracted with good efficiency. The deflection medium is a crystal material TeO2 . The power of the electrical signal is 2W. The corresponding diffraction...between 50 MHz and 100 MHz. The acoustooptical deflector used a birefregent TeO2 single crystal as the ultrasonic medium where the light deflection take...pair of glass substrates with sufficient thickness (> 1 mm). The thick glass plate reduces the spatial resolution of the fiberoptic plate. To reduce

Molecular characterization of resistance, virulence and clonality in vancomycin-resistant Enterococcus faecium and Enterococcus faecalis: A hospital-based study in Beijing, China.

PubMed

Yang, Jing-xian; Li, Tong; Ning, Yong-zhong; Shao, Dong-hua; Liu, Jing; Wang, Shu-qin; Liang, Guo-wei

2015-07-01

The incidence of vancomycin-resistant enterococcus (VRE) in China is increasing, the molecular epidemiology of VRE in China is only partly known. This study was conducted to assess the molecular characterization of resistance, virulence and clonality of 69 vancomycin-resistant Enterococcus faecium (VREfm) and seven vancomycin-resistant Enterococcus faecalis (VREfs) isolates obtained from a Chinese hospital between July 2011 and July 2013. The glycopeptide resistance genes (VanA and VanB) were screened by multiplex PCR. The presence of five putative virulence genes (esp, gelE, asa1, hyl and cylA) were evaluated by another multiplex PCR. Multilocus sequence typing (MLST) scheme was used to assess the clonality. All 76 VRE isolates exhibited VanA phenotype and harbored VanA gene. Esp was the only gene detected both in VREfm and VREfs strains, accounting for 89.9% and 42.9%, respectively. The hyl gene was merely positive in 27.5% of VREfm strains. MLST analysis demonstrated three STs (ST6, ST4 and ST470) in VREfs and twelve STs (ST78, ST571, ST17, ST564, ST389, ST18, ST547, ST341, ST414, ST343, ST262 and ST203) in VREfm, which were all designated as CC17 by eBURST algorithm. An outbreak of VREfm belonging to ST571 was found to happen within the neurology ward in this hospital. To our knowledge, this is the first report of ST6 (CC2) VREfs strains in China and the first outbreak report of VREfm strains belonging to ST571 around the world. Our data could offer important information for understanding the molecular features of VRE in China. Copyright © 2015 Elsevier B.V. All rights reserved.

Molecular Epidemiology of Vancomycin-Resistant Enterococcus faecium: a Prospective, Multicenter Study in South American Hospitals▿

PubMed Central

Panesso, Diana; Reyes, Jinnethe; Rincón, Sandra; Díaz, Lorena; Galloway-Peña, Jessica; Zurita, Jeannete; Carrillo, Carlos; Merentes, Altagracia; Guzmán, Manuel; Adachi, Javier A.; Murray, Barbara E.; Arias, Cesar A.

2010-01-01

Enterococcus faecium has emerged as an important nosocomial pathogen worldwide, and this trend has been associated with the dissemination of a genetic lineage designated clonal cluster 17 (CC17). Enterococcal isolates were collected prospectively (2006 to 2008) from 32 hospitals in Colombia, Ecuador, Perú, and Venezuela and subjected to antimicrobial susceptibility testing. Genotyping was performed with all vancomycin-resistant E. faecium (VREfm) isolates by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. All VREfm isolates were evaluated for the presence of 16 putative virulence genes (14 fms genes, the esp gene of E. faecium [espEfm], and the hyl gene of E. faecium [hylEfm]) and plasmids carrying the fms20-fms21 (pilA), hylEfm, and vanA genes. Of 723 enterococcal isolates recovered, E. faecalis was the most common (78%). Vancomycin resistance was detected in 6% of the isolates (74% of which were E. faecium). Eleven distinct PFGE types were found among the VREfm isolates, with most belonging to sequence types 412 and 18. The ebpAEfm-ebpBEfm-ebpCEfm (pilB) and fms11-fms19-fms16 clusters were detected in all VREfm isolates from the region, whereas espEfm and hylEfm were detected in 69% and 23% of the isolates, respectively. The fms20-fms21 (pilA) cluster, which encodes a putative pilus-like protein, was found on plasmids from almost all VREfm isolates and was sometimes found to coexist with hylEfm and the vanA gene cluster. The population genetics of VREfm in South America appear to resemble those of such strains in the United States in the early years of the CC17 epidemic. The overwhelming presence of plasmids encoding putative virulence factors and vanA genes suggests that E. faecium from the CC17 genogroup may disseminate in the region in the coming years. PMID:20220167

Vancomycin-Resistant Enterococci and Bacterial Community Structure following a Sewage Spill into an Aquatic Environment.

PubMed

Young, Suzanne; Nayak, Bina; Sun, Shan; Badgley, Brian D; Rohr, Jason R; Harwood, Valerie J

2016-09-15

Sewage spills can release antibiotic-resistant bacteria into surface waters, contributing to environmental reservoirs and potentially impacting human health. Vancomycin-resistant enterococci (VRE) are nosocomial pathogens that have been detected in environmental habitats, including soil, water, and beach sands, as well as wildlife feces. However, VRE harboring vanA genes that confer high-level resistance have infrequently been found outside clinical settings in the United States. This study found culturable Enterococcus faecium harboring the vanA gene in water and sediment for up to 3 days after a sewage spill, and the quantitative PCR (qPCR) signal for vanA persisted for an additional week. Culturable levels of enterococci in water exceeded recreational water guidelines for 2 weeks following the spill, declining about five orders of magnitude in sediments and two orders of magnitude in the water column over 6 weeks. Analysis of bacterial taxa via 16S rRNA gene sequencing showed changes in community structure through time following the sewage spill in sediment and water. The spread of opportunistic pathogens harboring high-level vancomycin resistance genes beyond hospitals and into the broader community and associated habitats is a potential threat to public health, requiring further studies that examine the persistence, occurrence, and survival of VRE in different environmental matrices. Vancomycin-resistant enterococci (VRE) are harmful bacteria that are resistant to the powerful antibiotic vancomycin, which is used as a last resort against many infections. This study followed the release of VRE in a major sewage spill and their persistence over time. Such events can act as a means of spreading vancomycin-resistant bacteria in the environment, which can eventually impact human health. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Biological conversion of the aqueous wastes from hydrothermal liquefaction of algae and pine wood by Rhodococci

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

He, Yucai; Li, Xiaolu; Xue, Xiaoyun

In this study, R. opacus PD630, R. jostii RHA1, R. jostii RHA1 VanA-, and their co-culture were employed to convert hydrothermal liquefaction aqueous waste (HTLAW) into lipids. After 11 days, the COD reduction of algal-HTLAW reached 93.4% and 92.7% by R. jostii RHA1 and its mutant VanA-, respectively. Woody-HTLAW promoted lipid accumulation of 0.43 g lipid/g cell dry weight in R. opacus PD630 cells. Additionally, the total number of chemicals in HTLAW decreased by over 1/3 after 7 days of coculture, and 0.10 g/L and 0.46 g/L lipids were incrementally accumulated in the cellular mass during the fermentation of wood-more » and algal-HTLAW, respectively. The GC-MS data supported that different metabolism pathways were followed when these Rhodococci strains degraded algae- and woody-HTLAW. These results indicated promising potential of bioconversion of under-utilized carbon and toxic compounds in HTLAW into useful products by selected Rhodococci.« less

Multiple Antibiotic Resistance Gene Transfer from Animal to Human Enterococci in the Digestive Tract of Gnotobiotic Mice

PubMed Central

Moubareck, C.; Bourgeois, N.; Courvalin, P.; Doucet-Populaire, F.

2003-01-01

It has been proposed that food animals represent the source of glycopeptide resistance genes present in enterococci from humans. We demonstrated the transfer of vanA and of other resistance genes from porcine to human Enterococcus faecium at high frequency in the digestive tract of gnotobiotic mice. Tylosin in the drinking water favored colonization by transconjugants. PMID:12937011

Chemical Processing of Structural Ceramics and Composites

DTIC Science & Technology

1988-09-01

aluminum isopropoxide (Eq. 2). Silicon alkoxide was purchased (Alfa Products) since it is relatively stable. Mg + 2C2 H 5OH ---> Mg(OC 2H5 )2 + 1/2H 2...hydrolysis of mullite precursor mixed alkoxides (TEOS and aluminum isopropoxide ) were studied. The effect of pH on hydrolysis was significant due to the...followed by IR measurements. A stoichiometric amount of TEOS was added to aluminum isopropoxide , refluxed for 48 hours, then the excess isopropyl

Design and Demonstration of an Acousto-Optic Time-Integrating Correlator with a Large a Parallel Gain

DTIC Science & Technology

1993-01-01

Deoxyribose nucleicacid DPP: Digital Post-Processor DREO Detence Research Establishment Ottawa RF: Radio Frequency TeO2 : tellurium dioxide TIC: Time... TeO2 is 620 m/s, a device with a 100-As aperture device is 62-mm long. To take advantage of the full interaction time of these Bragg cells, the whole...INCLUDED IN THE DIGITAL POST-PROCESSOR HARDWARE Characteristics of Bandwidth Center Frequency Bragg Cell glass (bulk 100 MHz 150 MHz interaction) iNbO3

Error Measurements in an Acousto-Optic Tunable Filter Fiber Bragg Grating Sensor System

DTIC Science & Technology

1994-05-01

for an ideal AOTF, at 833 and 838 nm using a TeO2 crystal ............................ 33 Figure 3.12. Frequency characteristics of Equation (3.43...multiple channels in an AOTF requires the presence of multiple RF frequencies to establish the complex grating. Since the crystal used in the AOTF ( TeO2 ) is...in germano- silicate glass . This index modulation, Bragg grating, acts as an optical band rejection filter for those wavelengths that meet the Bragg

Magnetic sporopollenin-cyanopropyltriethoxysilane-dispersive micro-solid phase extraction coupled with high performance liquid chromatography for the determination of selected non-steroidal anti-inflammatory drugs in water samples.

PubMed

Abd Wahib, Siti Munirah; Wan Ibrahim, Wan Aini; Sanagi, Mohd Marsin; Kamboh, Muhammad Afzal; Abdul Keyon, Aemi S

2018-01-12

A facile dispersive-micro-solid phase extraction (D-μ-SPE) method coupled with HPLC for the analysis of selected non-steroidal anti-inflammatory drugs (NSAIDs) in water samples was developed using a newly prepared magnetic sporopollenin-cyanopropyltriethoxysilane (MS-CNPrTEOS) sorbent. Sporopollenin homogenous microparticles of Lycopodium clavatum spores possessed accessible functional groups that facilitated surface modification. Simple modification was performed by functionalization with 3-cyanopropyltriethoxysilane (CNPrTEOS) and magnetite was introduced onto the biopolymer to simplify the extraction process. MS-CNPrTEOS was identified by infrared spectrometrywhile the morphology and the magnetic property were confirmed by scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), respectively. To maximize the extraction performance of ketoprofen, ibuprofen, diclofenac and mefenamic acid using the proposed MS-CNPrTEOS, important D-μ-SPE parameters were comprehensively optimized. The optimum extraction conditions were sorbent amount, 40 mg; extraction time, 5 min; desorption time; 5 min; sample volume, 15 mL; sample pH 2.0; and salt addition, 2.5% (w/v). The feasibility of the developed method was evaluated using spiked tap water, lake water, river water and waste water samples. Results showed that ketoprofen and ibuprofen were linear in the range of 1.0-1000 μg L -1 whilst diclofenac and mefenamic acid were linear in the range 0.8-500 μg L -1 . The results also showed good detection limits for the studied NSAIDs in the range of 0.21-0.51 μg L -1 and good recoveries for spiked water samples in the range of 85.1-106.4%. The MS-CNPrTEOS proved a promising dispersive sorbent and applicable to facile and rapid assay of NSAIDs in water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of probiotics and thyme essential oil on the essential amino acid content of the broiler chicken meat.

PubMed

Alfaig, Ebrahim; Angelovičova, Maria; Kral, Martin; Bučko, Ondrej

2014-01-01

Differences in the types and percentages of essential amino acids (EAAs) in food could influence the value of protein consumed and proteins with a high content of EAAs are the most important components of poultry meat. The use of probiotics for meat and carcass quality improvement has been questioned, while feed supplementation with thyme essential oil (TEO) could be considered as useful natural supplement to be applied in the poultry industry to improve meat quality. Day-old broilers Ross 308 (n = 400) were randomly divided into four groups based on the feed supplement as follows: control, probiotics 0.05%, TEO 0.05% and combination of probiotics and TEO, while the fattening period was 42 days. Six birds of both sexes from each group were selected as a sample, slaughtered and then stored (-18°C) for 6 months till the analysis. The muscular homogeneous sample (50 g) from the breast and thigh of each sample bird was analysed by the Fourier Transform Infrared Spectroscopy method using the device Nicolet 6700. The essential amino acids content was determined and the quality indicators include chemical score, amino acid score, EAA index and biological value were calculated. The obtained results show that for all the tested EAAs of the breast and thigh muscles, the content numerically increased gradually and progressively within the groups as the control scored the minimum followed by the probiotics group, then the combination group and finally the TEO group which scored the highest results. It can be concluded that the TEO promoted the increase of all the EAAs and consequently the quality indicators with significant different compared with the control group and significantly different for some EAAs and quality indicators compared with the probiotics group and the combination group.

Short-range structure of barium tellurite glasses and its correlation with stress-optic response

NASA Astrophysics Data System (ADS)

Kaur, Amarjot; Khanna, Atul; Fábián, Margit

2018-06-01

The atomic parameters of metal ion-oxygen speciation such as bond-lengths and nearest neighbor distances for Ba-O, Te-O and O-O pairs, co-ordination numbers and bond angle distributions for O-Ba-O, O-Te-O and O-O-O linkages are determined by neutron diffraction and Reverse Monte Carlo simulations on the series of xBaO-(100-x)TeO2 glasses containing 10, 15 and 20 mol% BaO. The glass network depolymerizes and the average Te-O co-ordination number decreases from 3.60 ± 0.02 to 3.48 ± 0.02 with increase in BaO concentration. Te-O bond lengths are in the range: 1.97 ± 0.01–1.92 ± 0.01 Å. Ba2+ is mostly in octahedral coordination and the Ba-O bond lengths are in the range: 2.73 ± 0.01 to 2.76 ± 0.03 Å. Te-O co-ordination number is also determined by Raman spectroscopy and it shows good agreement with the neutron data. The short-range structural properties i.e. metal ion coordination number (Nc) and bond lengths (d) were correlated with the stress-optic response. The bonding characteristic, Br values were determined from the structural data of xBaO-(100-x)TeO2 glasses and were used to predict the stress-induced birefringence properties.

Proceedings SPIE: Conference Digest, International Conference on Infrared and Millimeter Waves (18th) Held in Colchester, United Kingdom on 6-10 September 1993. Volume 2104

DTIC Science & Technology

1993-09-10

effective dielectric constant appears to decrease upon the substitution of PbO, 1. INRODUCTION In V2 05 - TeO2 glasses several studies on equilibrium... glass increases as TeOg is partially replaced by PbO. Previous studies on V20 5 - TeO2 system 4.5 have reported three Infrared absorption bands at 1010...Laboratory, Dr, K,S. Krishnan Road, New Delhi 110012, India. Th4., REFLECTANCE STUDY OF TM,O. GLASSES - AMemon, M,N.Khan, SAI-Dallal, Department of

Photonics in Switching. Organization of the 1993 Photonics Science Topical Meetings Held in Palm Springs, California on March 15 - 17, 1993. Technical Digest

DTIC Science & Technology

1993-03-17

placed on the number of inputs and outputs. For the TeO2 material used in this design, the TB is approximately 1000. Due to the over-resolved...Design of the acoustooptic crossbar switch Figure 2 shows a numerical simulation of the momentum space of an 8 by 8 switch in TeO2 . This switch...results Figure 4 shows switching results from a preliminary demonstration of a three by three switch in a beam-steered flint glass cell. The scope trace

Optical Interarray Processing.

DTIC Science & Technology

1980-03-01

of around 30 frames/sec. One dimensional input transducers such as acousto-optic Bragg cells have much higher frame rates. For example, a TeO2 Bragg...Conventional manufacturing processes such as grinding and polish- ing a glass piece would be difficult if not impossible to apply to the fabrication of such...time-bandwidth product (TBW). An acoustic shear wave in a TeO2 Bragg cell will propagate with a speed of 617 meters/ sec, while the practical physical

Methods for Reachability-based Hybrid Controller Design

DTIC Science & Technology

2012-05-10

approaches for airport runways ( Teo and Tomlin, 2003). The results of the reachability calculations were validated in extensive simulations as well as...UAV flight experiments (Jang and Tomlin, 2005; Teo , 2005). While the focus of these previous applications lies largely in safety verification, the work...B([15, 0],a0)× [−π,π])\\ V,∀qi ∈ Q, where a0 = 30m is the protected radius (chosen based upon published data of the wingspan of a Boeing KC -135

Endometrial stromal tumors: the new WHO classification.

PubMed

Conklin, Christopher M J; Longacre, Teri A

2014-11-01

Endometrial stromal tumors are rare uterine mesenchymal neoplasms that have intrigued pathologists for years, not only because they commonly pose diagnostic dilemmas, but also because the classification and pathogenesis of these tumors has been widely debated. The current World Health Organization recognizes 4 categories of endometrial stromal tumor: endometrial stromal nodule (ESN), low-grade endometrial stromal sarcoma (LG-ESS), high-grade endometrial stromal sarcoma (HG-ESS), and undifferentiated uterine sarcoma (UUS). uterine sarcoma. These categories are defined by the presence of distinct translocations as well as tumor morphology and prognosis. Specifically, the JAZF1-SUZ12 (formerly JAZF1-JJAZ1) fusion identifies a large proportion of ESN and LG-ESSs, whereas the YWHAE-FAM22 translocation identifies HG-ESSs. The latter tumors appear to have a prognosis intermediate between LG-ESS and UUS, which exhibits no specific translocation pattern. This review (1) presents the clinicopathologic features of endometrial stromal tumors; (2) discusses their immunophenotype; and (3) highlights the recent advances in molecular genetics which explain their pathogenesis and lend support for a new classification system.

Preparation of sponge-reinforced silica aerogels from tetraethoxysilane and methyltrimethoxysilane for oil/water separation

NASA Astrophysics Data System (ADS)

Li, Ming; Jiang, Hongyi; Xu, Dong

2018-04-01

Polyurethane sponge-reinforced silica aerogels based on tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) were fabricated by a facile method through sol-gel reaction followed by ambient pressure drying. In sponge-reinforced silica aerogels, nanoporous aerogel aggregates fill in the pores of polyurethane sponge. The sponge-reinforced aerogels are hydrophobic and oleophilic and show extremely high absorption for machine oil (10.6 g g‑1 for TEOS-based aerogel and 9.2 g g‑1 for MTMS-based aerogel). In addition, the sponge-reinforced aerogel composites exhibit notable improvements with regards to mechanical properties. The compressive strength was enhanced obviously up to about 349 KPa for TEOS-based aerogel and 60 KPa for MTMS-based aerogel. Specially, sponge-reinforced silica aerogels based on MTMS drastically shrank upon loading and then recovered to the original size when unloaded. The property differences of the sponge-reinforced silica aerogels caused by the two precursors were discussed in terms of morphologies, pore size distributions and chemical structure.

A thermodynamic database for tellurium-bearing systems relevant to nuclear technology

NASA Astrophysics Data System (ADS)

Chattopadhyay, G.; Juneja, J. M.

1993-06-01

A thermodynamic database for tellurium-bearing condensed phases and gaseous species which are relevant to nuclear technology is presented. It contains phase diagrams of the binary systems, PdTe, RhTe, PuTe, SmTe, CsTe, ZrTe, of the ternary systems, ZrTeO, MoTeO, AgTeO, UTeO, CsTeO, BaTeO as well as thermodynamic data for crystalline and liquid Te, for the solid phases Cs 2Te, Ag 2Te, SnTe, BaTe, CeTe, SmTe, RuTe 2, ZrTe 2, Fe 0.53Te 0.47, Mo 0.43Te 0.57, Cr 0.43Te 0.57, Ni 0.5Te 0.4, Cs 2TeO 3 and for the gaseous species, Te, Te 2, TeO, TeO 2, TeO(OH) 2, H 2Te, TeI, TeI 2, TeI 4, TeOI 2, SnTe, Sn 2Te 2, SnTe 2.

The Effect of Remelting on the Physical Properties of Borotellurite Glass Doped with Manganese

PubMed Central

Hashim, Syed Putra Hashim Syed; Sidek, Haji Abdul Aziz; Halimah, Mohamed Kamari; Matori, Khamirul Amin; Yusof, Wan Mohamad Daud Wan; Zaid, Mohd Hafiz Mohd

2013-01-01

A systematic set of borotellurite glasses doped with manganese (1–x) [(B2O3)0.3(TeO2)0.7]-xMnO, with x = 0.1, 0.2, 0.3 and 0.4 mol%, were successfully synthesized by using a conventional melt and quench-casting technique. In this study, the remelting effect of the glass samples on their microstructure was investigated through density measurement and FT-IR spectra and evaluated by XRD techniques. Initial experimental results from XRD evaluation show that there are two distinct phases of glassy and crystallite microstructure due to the existence of peaks in the sample. The different physical behaviors of the studied glasses were closely related to the concentration of manganese in each phase. FTIR spectra revealed that the addition of manganese oxide contributes the transformation of TeO4 trigonal bipyramids with bridging oxygen (BO) to TeO3 trigonal pyramids with non-bridging oxygen (NBO). PMID:23296276

Optical Signal Processing.

DTIC Science & Technology

1986-10-31

constructed from TeO2 sisting of lenses L6 and L- and a cylindrical lens C- material which is oriented to operate in the slow shear shape the Bragg...to focus the light into a horizontal line for efficient illumination. The Bragg cells are constructed from TeO2 material which is oriented to operate...source is a 10 mW He-Ne laser for which = 632.8 nm. The holographic element was constructed on a SO-120 glass plate with a reference-to-signal beam

System Design, Implementation, and Evaluation of the Optical Broadband Correlator

DTIC Science & Technology

1994-09-20

shear-mode TeO2 , Model No. N45075-6-20, manufactured by Newport Electro- Optic Systems with a length of 75 pjs, acoustic direction 1110], optical...optical aperture (or useful length) TOA of our cells are shown in Table 3. The Bragg cells are shear-mode TeO2 , Model No. N45075-6-20, manufactured by...focusing or integrating (Fourier transform) lens is a laser diode glass doublet Model 06LAI013/076, from Melles Griot. Its focal length is 145 nun at 830

Analysis and Characterization of an Acousto-Optic Beam Position Control System

DTIC Science & Technology

2002-07-01

glass or plastic. This device can be viewed as a medium where light interacts with sound yielding a diffracted light beam. Bragg cells can operate in...by “optical activity” is considered to be very small for TeO2 [2]. The birefringence is due to the fact the index of refraction in for the incident...equations describes behavior of the acousto-optic device. The acoustic velocity can be expressed as follows. azat vvv Θ+Θ= 22222 sincos For TeO2 vt=616 m

Sol-Gel synthesis of MgO-SiO2 glass compositions having stable liquid-liquid immiscibility

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1987-01-01

MgO-SiO2 glasses containing up to 15 mol % MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol % MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol % MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol %) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

Sol-gel synthesis of magnesium oxide-silicon dioxide glass compositions

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1988-01-01

MgO-SiO2 glasses containing up to 15 mol pct MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol pct MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol pct MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol pct) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

Influence of crosslinker structure on performance of functionalised organic-inorganic hybrid sol-gel coating

NASA Astrophysics Data System (ADS)

Vasiljević, J.; Zorko, M.; Štular, D.; Tomšič, B.; Jerman, I.; Orel, B.; Medved, J.; Simončič, B.

2017-10-01

This research aimed to investigate the influence of the co-condensation of the three different organofunctional trialkoxysilane precursors with two different crosslinkers, i.e. tetraethoxysilane or organocyclotetrasiloxane on the performance and the washing fastness of this multicomponent multifunctional sol-gel coating on cellulose fibres. To this aim, a three-component equimolar sol mixture (MC), which included 1H,1H,2H,2H-perfluorooctyltriethoxysilane (SiF), 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (SiQ) and P,P-diphenyl-N-(3-(trimethoxysilyl)propyl) phosphinic amide (SiP) in combination with two different concentrations of TEOS (T and 3T) or organocyclotetrasiloxane 2,4,6,8-tetrakis(2-(diethoxy(methyl)silyl)ethyl)-2,4,6,8-tetramethyl-cyclotetrasiloxane (T4) as crosslinkers, was applied to the cotton fibres by a pad-dry-cure process. The functional properties of the coated samples before and after repeated washing were investigated by the water θ (W) and n-hexadecane θ (C16) static contact angle as well as water sliding (roll-off) (α) angle measurements. The inclusion of both TEOS and T4 into the MC sol increased the hydrophobic affect and simultaneously decreased the oleophobic effect of the MC coating. These phenomena were more pronounced for higher concentration of TEOS and T4 crosslinker. The inclusion of T4 into the MC sol improved the coating washing fastness to a significantly higher extent than the inclusion of TEOS, with respect to the applied concentrations.

Mixed Single/Double Precision in OpenIFS: A Detailed Study of Energy Savings, Scaling Effects, Architectural Effects, and Compilation Effects

NASA Astrophysics Data System (ADS)

Fagan, Mike; Dueben, Peter; Palem, Krishna; Carver, Glenn; Chantry, Matthew; Palmer, Tim; Schlacter, Jeremy

2017-04-01

It has been shown that a mixed precision approach that judiciously replaces double precision with single precision calculations can speed-up global simulations. In particular, a mixed precision variation of the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF) showed virtually the same quality model results as the standard double precision version (Vana et al., Single precision in weather forecasting models: An evaluation with the IFS, Monthly Weather Review, in print). In this study, we perform detailed measurements of savings in computing time and energy using a mixed precision variation of the -OpenIFS- model. The mixed precision variation of OpenIFS is analogous to the IFS variation used in Vana et al. We (1) present results for energy measurements for simulations in single and double precision using Intel's RAPL technology, (2) conduct a -scaling- study to quantify the effects that increasing model resolution has on both energy dissipation and computing cycles, (3) analyze the differences between single core and multicore processing, and (4) compare the effects of different compiler technologies on the mixed precision OpenIFS code. In particular, we compare intel icc/ifort with gnu gcc/gfortran.

Structural damage identification using an enhanced thermal exchange optimization algorithm

NASA Astrophysics Data System (ADS)

Kaveh, A.; Dadras, A.

2018-03-01

The recently developed optimization algorithm-the so-called thermal exchange optimization (TEO) algorithm-is enhanced and applied to a damage detection problem. An offline parameter tuning approach is utilized to set the internal parameters of the TEO, resulting in the enhanced heat transfer optimization (ETEO) algorithm. The damage detection problem is defined as an inverse problem, and ETEO is applied to a wide range of structures. Several scenarios with noise and noise-free modal data are tested and the locations and extents of damages are identified with good accuracy.

Scanner Development

DTIC Science & Technology

1978-07-01

experience with TeO2 indicates th at 40 percent of the center frequency value is more easily obtainable. The 150 MHz bandwidth corresponds to a center...acousto-optic interaction bandwidth. Substituting the value for n m 2.3 as the average of ne and no of TeO2 and ko - 514.5 nm in Equation (2.2-6), we have L...bandwidth can be fabricated using low cost SF-8 glass . A center frequency of 70 MHz is S, • chosen to produce a reasonably flat scan. The AOND cell

Interface Properties and Surface Leakage of HgCdTe Photodiodes.

DTIC Science & Technology

1980-01-01

these techniques, we found that (a) the com- position of a 1200 )anodic film is 68% TeO2 , 27% CdO, and 6% HgO, and (b) the cations, especially the Hg...of TeO2 (Fig. 1); (b) irradiation with an electron beam of a few keV energy can convert the surface layer (10-100 1) of (Rg,Cd)Te into CdTe (Fig. 2...remove the scratches. The polishing cloth was secured to a glass olishing disk which is not affected by the corrosive nature of the etch - a 5

Acousto-Optic Processing of 2-D Signals Using Temporal and Spatial Integration.

DTIC Science & Technology

1986-04-29

given a, B is in the range Teo2 Bragg cell, with 30 MHz dB bandwidth at 2ោ or a2 <O<m if the images involved are real 820 nm (the laser wavelength...laboratory TeO2 devices with of additive interference, however, DR’ is reduced significantly. Let us up to 70 As delay. Finally, the CCD must have 512 + 64...and b(t) inte- grated over a finite interval T. . Flint glass acoustooptic cells driven at a center fre- - quency of 70 MHz were used in the

Improved Second-Generation 3-D Volumetric Display System. Revision 2

DTIC Science & Technology

1998-10-01

computer control, uses infrared lasers to address points within a rare-earth-infused solid glass cube. Already, simple animated computer-generated images...Volumetric Display System permits images to be displayed in a three- dimensional format that can be observed without the use of special glasses . Its...MM 120 nm 60 mm nI POLARIZING I $-"• -’’""BEAMSPLI’i-ER ) 4P40-MHz 50-MHz BW PLRZN i TeO2 MODULATORS TeO2 DEFLECTORS Figure 1-4. NEOS four-channel

Acousto-Optic Applications for Multichannel Adaptive Optical Processor

DTIC Science & Technology

1992-06-01

AO cell and the two- channel line-scan camera system described in Subsection 4.1. The AO material for this IntraAction AOD-70 device was flint glass (n...Single-Channel 1.68 (flint glass ) 60,.0 AO Cell Multichannel 2.26 (TeO 2) 20.0 AO Cell Beam splitter 1.515 ( glass ) 50.8 Multichannel correlation was...Tone Intermodulation Dynamic Ranges of Longitudinal TeO2 Bragg Cells for Several Acoustic Power Densities 4-92 f f2 f 3 1 t SOURCE: Reference 21 TR-92

Aerodynamic Performance Predictions of a SA- 2 Missile Using Missile DATCOM

DTIC Science & Technology

2009-09-01

transformation that is given by Eqs. (4) and (5). Eqs. (8)–(10) show the formulation in the body and wind axis terminology. 2,0D AC C kC   L (8) 10 cos...by Teo (2008) using Missile LAB code. However, the missile geometry then was set up from a rudimentary drawing and not one that represented a high...provided by MSIC. These particular cases were run forcing turbulent flow with a surface roughness of 0.001016 cm, which was found by Teo (2008) to

Effect of Electrospun Nanofibers on the Short Beam Strength of Laminated Fiberglass Composite

NASA Astrophysics Data System (ADS)

Shinde, Dattaji K.

High specific modulus and strength are the most desirable properties for the material used in structural applications. Composite materials exhibit these properties and over the last decade, their usage has increased significantly, particularly in automotive, defense, and aerospace applications. The major cause of failures in composite laminates is due to delaminations. Delamination in composite laminates can occur due to fatigue, low velocity impact and other loadings modes. Conventional methods like "through-the-thickness stitching" or "Z-Pinning" have limitations for improving flexural and interlaminar properties in woven composites due to the fact that while improving interlaminar properties, the presence of stitches or Z pins affects in-plane properties. This study investigates the flexural behavior of fiberglass composites interleaved with non-woven Tetra Ethyl Orthosilicate (TEOS) electrsopsun nanofibers (ENFs). TEOS ENFs were manufactured using an electrospinning technique and then sintered. Nanoengineered beams were fabricated by interleaving TEOS ENFs between the laminated fiberglass composites to improve the flexural properties. TEOS ENFs, resin film, and failed fiberglass laminated composites with and without nanofibers were characterized using SEM Imaging and ASTM standard testing methods. A hybrid composite was made by interleaving a non-woven sheet of TEOS ENFs between the fiberglass laminates with additional epoxy resin film and fabricated using the out of autoclave vacuum bagging method. Four commonly used stacking sequences of fiberglass laminates with and without nanofibers were used to study the progressive failure and deformation mechanics under flexural loadings. The experimental study has shown significant improvements in short beam strength and strain energy absorption in the nanoengineered laminated fiberglass composites before complete failure. The modes were investigated by performing detailed fractographic examination of failed specimens

Numerical implementation and oceanographic application of the thermodynamic potentials of water, vapour, ice, seawater and air - Part 2: The library routines

NASA Astrophysics Data System (ADS)

Wright, D. G.; Feistel, R.; Reissmann, J. H.; Miyagawa, K.; Jackett, D. R.; Wagner, W.; Overhoff, U.; Guder, C.; Feistel, A.; Marion, G. M.

2010-03-01

The SCOR/IAPSO1 Working Group 127 on Thermodynamics and Equation of State of Seawater has prepared recommendations for new methods and algorithms for numerical estimation of the thermophysical properties of seawater. As an outcome of this work, a new International Thermodynamic Equation of Seawater (TEOS-10) was endorsed by IOC/UNESCO2 in June 2009 as the official replacement and extension of the 1980 International Equation of State, EOS-80. As part of this new standard a source code package has been prepared that is now made freely available to users via the World Wide Web. This package includes two libraries referred to as the SIA (Sea-Ice-Air) library and the GSW (Gibbs SeaWater) library. Information on the GSW library may be found on the TEOS-10 web site (TEOS-10.org"target="_blank">http://www.TEOS-10.org). This publication provides an introduction to the SIA library which contains routines to calculate various thermodynamic properties as discussed in the companion paper. The SIA library is very comprehensive, including routines to deal with fluid water, ice, seawater and humid air as well as equilibrium states involving various combinations of these, with equivalent code developed in different languages. The code is hierachically structured in modules that support (i) almost unlimited extension with respect to additional properties or relations, (ii) an extraction of self-contained sub-libraries, (iii) separate updating of the empirical thermodynamic potentials, and (iv) code verification on different platforms and between different languages. Error trapping is implemented to identify when one or more of the primary routines are accessed significantly beyond their established range of validity. The initial version of the SIA library is available in Visual Basic and FORTRAN as a supplement to this publication and updates will be maintained on the TEOS-10 web site. 1 SCOR/IAPSO: Scientific Committee on Oceanic Research

Numerical implementation and oceanographic application of the thermodynamic potentials of liquid water, water vapour, ice, seawater and humid air - Part 2: The library routines

NASA Astrophysics Data System (ADS)

Wright, D. G.; Feistel, R.; Reissmann, J. H.; Miyagawa, K.; Jackett, D. R.; Wagner, W.; Overhoff, U.; Guder, C.; Feistel, A.; Marion, G. M.

2010-07-01

The SCOR/IAPSO1 Working Group 127 on Thermodynamics and Equation of State of Seawater has prepared recommendations for new methods and algorithms for numerical estimation of the the thermophysical properties of seawater. As an outcome of this work, a new International Thermodynamic Equation of Seawater (TEOS-10) was endorsed by IOC/UNESCO2 in June 2009 as the official replacement and extension of the 1980 International Equation of State, EOS-80. As part of this new standard a source code package has been prepared that is now made freely available to users via the World Wide Web. This package includes two libraries referred to as the SIA (Sea-Ice-Air) library and the GSW (Gibbs SeaWater) library. Information on the GSW library may be found on the TEOS-10 web site (TEOS-10.org" target="_blank">http://www.TEOS-10.org). This publication provides an introduction to the SIA library which contains routines to calculate various thermodynamic properties as discussed in the companion paper. The SIA library is very comprehensive, including routines to deal with fluid water, ice, seawater and humid air as well as equilibrium states involving various combinations of these, with equivalent code developed in different languages. The code is hierachically structured in modules that support (i) almost unlimited extension with respect to additional properties or relations, (ii) an extraction of self-contained sub-libraries, (iii) separate updating of the empirical thermodynamic potentials, and (iv) code verification on different platforms and between different languages. Error trapping is implemented to identify when one or more of the primary routines are accessed significantly beyond their established range of validity. The initial version of the SIA library is available in Visual Basic and FORTRAN as a supplement to this publication and updates will be maintained on the TEOS-10 web site. 1SCOR/IAPSO: Scientific Committee on Oceanic Research

Synthesis, characterization and optical properties of non-traditional tellurite-selenite glasses

NASA Astrophysics Data System (ADS)

Bachvarova-Nedelcheva, A.; Iordanova, R.; Kostov, K. L.; Ganev, V.; Yordanov, St.

2014-06-01

This study continues our investigations on non-traditional tellurite-selenite amorphous materials. Two glasses containing TeO2, SeO2, MoO3 and V2O5 were obtained at high oxygen pressure (P = 36 MPa) using pure oxides as precursors. The real bulk chemical composition of both glasses was verified by LA-ICP-MS method. The glasses were characterized by X-ray diffraction, Scanning Electron Microscopy (SEM), Differential Thermal Analysis (DTA), UV-Vis, XPS, IR and EPR spectroscopy. According to DTA the glass transition temperature (Tg) is below 300 °C. Both glasses were subjected to heat treatment (300 °C - 12 h) and as a result no crystallization was observed. The main building units (TeO3, TeO4, Mo2O8, and SеО3) were determined by IR and X-ray photoelectron spectroscopy and the existence of mixed bridging bonds only, which build up the amorphous network. It was established by UV-Vis that the obtained glasses are transparent above 550 nm and they were red colored.

Study of oxygen/tetraethoxysilane plasmas in a helicon reactor using optical emission spectroscopy and mass spectrometry

NASA Astrophysics Data System (ADS)

Aumaille, K.; Granier, A.; Schmidt, M.; Grolleau, B.; Vallée, C.; Turban, G.

2000-08-01

Oxygen/tetraethoxysilane (O2/TEOS) plasmas created in a low-pressure (2 mTorr) rf helicon reactor have been studied by optical emission spectroscopy and mass spectrometry as a function of the rf (13.56 MHz) power injected into the plasma, which is varied from 25 to 300 W. Complementary measurements for the interpretation of the mass spectrometric data have also been carried out using the threshold ionization mass spectrometry technique. It is shown that valuable information on the parent molecules is obtained by both optical emission spectroscopy and threshold ionization mass spectrometry techniques. At low rf power TEOS molecules and organic compounds like hydrocarbons (CH4, C2H2) and alcohols (CH3CH2OH) as well as H2, H2O, CO, O2, CO2 are observed. At high rf power TEOS and O2 molecules are totally or mostly depleted, the share of hydrocarbons decreases and carbon monoxide, carbon dioxide, water and hydrogen become the essential parts of the gas phase.

Preparation of micro-porous bioceramic containing silicon-substituted hydroxyapatite and beta-tricalcium phosphate.

PubMed

Fuh, Lih-Jyh; Huang, Ya-Jing; Chen, Wen-Cheng; Lin, Dan-Jae

2017-06-01

Dimensional instability caused by sintering shrinkage is an inevitable drawback for conventional processing of hydroxyapatite (HA). A new preparation method for biphasic calcium phosphates was developed to increase micro pores and biodegradation without significant dimensional change. Powder pressed HA discs, under 100MPa, were immersed in a colloidal mixture of tetraethoxysilane (TEOS) and ammonium hydroxide for 10min, followed by drying, and then were sintered at 900°C, 1050°C, and 1200°C, respectively. Comparing with pure HA discs, the newly prepared product sintered up to 1200°C contained silicon substituted HA, beta-tricalcium phosphate, and calcium silicate with better micro-porosity, high specific surface area, less sintering shrinkage and the strength maintained. The cytocompatibility test demonstrated a better viability for D1 mice stem cells cultured on TEOS treated HA for 14days compared to the pure HA. This simple TEOS sol-gel pretreatment has the potential to be applied to any existing manufacturing process of HA scaffold for better control of sintering shrinkage, create micropores, and increase biodegradation. Copyright © 2017 Elsevier B.V. All rights reserved.

Acousto-optical and SAW propagation characteristics of temperature stable multilayered structures based on LiNbO3 and diamond

NASA Astrophysics Data System (ADS)

Shandilya, Swati; Sreenivas, K.; Gupta, Vinay

2008-01-01

Theoretical studies on the surface acoustic wave (SAW) properties of c-axis oriented LiNbO3/IDT/diamond and diamond/IDT/128° rotated Y-X cut LiNbO3 multilayered structures have been considered. Both layered structures exhibit a positive temperature coefficient of delay (TCD) characteristic, and a zero TCD device is obtained after integrating with an over-layer of either tellurium dioxide (TeO2) or silicon dioxide (SiO2). The presence of a TeO2 over-layer enhanced the electromechanical coupling coefficients of both multilayered structures, which acts as a better temperature compensation layer than SiO2. The temperature stable TeO2/LiNbO3/IDT/diamond layered structure exhibits good electromechanical coefficient and higher phase velocity for SAW device applications. On the other hand, a high acousto-optical (AO) figure of merit (30-37) × 10-15 s3 kg-1 has been obtained for the temperature stable SiO2/diamond/IDT/LiNbO3 layered structure indicating a promising device structure for AO applications.

125Te NMR Probes of Tellurium Oxide Crystals: Shielding-Structure Correlations.

PubMed

Garaga, Mounesha N; Werner-Zwanziger, Ulrike; Zwanziger, Josef W

2018-01-16

The local environments around tellurium atoms in a series of tellurium oxide crystals were probed by 125 Te solid-state NMR spectroscopy. Crystals with distinct TeO n units (n from 3 to 6), including Na 2 TeO 3 , α-TeO 2 and γ-TeO 2 , Te 2 O(PO 4 ) 2 , K 3 LaTe 2 O 9 , BaZnTe 2 O 7 , and CsYTe 3 O 8 were studied. The latter four were synthesized through a solid-state process. X-ray diffraction was used to confirm the successful syntheses. The 125 Te chemical shift was found to exhibit a strong linear correlation with the Te coordination number. The 125 Te chemical-shift components (δ 11 , δ 22 , and δ 33 ) of the TeO 4 units were further correlated to the O-Te-O-bond angles. With the aid of 125 Te NMR, it is likely that these relations can be used to estimate the coordination states of Te atoms in unknown Te crystals and glasses.

Enhanced frequency upconversion in Er3+-Yb3+ codoped heavy metal oxides based tellurite glasses.

PubMed

Azam, Mohd; Rai, Vineet Kumar

2018-01-24

The spectroscopic investigations on the Er 3+ /Yb 3+ ions doped/codoped TeO 2 -ZnO (TZ), TeO 2 -ZnO-WO 3 (TZW) and TeO 2 -ZnO-WO 3 -TiO 2 (TZWTi) heavy metal oxide (HMO) glasses have been made. The absorption, photoluminescence, decay curve and Judd-Ofelt analysis have been performed to optimise the optical properties of the Er 3+ /Yb 3+ ions. The effect of incorporation of HMOs like WO 3 and TiO 2 in the Er 3+ /Yb 3+ doped/codoped TZ glass on its optical properties have been investigated. The enhancement in upconversion emission intensity has been explained on the basis of efficient energy transfer and inhomogeneous local field generation around the rare earth ions. The spectroscopic quality factor, absorption and stimulated emission cross-sections, optical gain, quantum efficiency (∼17.53%), energy transfer efficiency (∼61.64%), colour purity (∼94.7%) and ionic nature of the bonding have been determined. The Er 3+ -Yb 3+ -TZWTi glass can be used in visible lasers, yellowish green optical devices and home appliances.

AC Conductivity and Dielectric Properties of Borotellurite Glass

NASA Astrophysics Data System (ADS)

Taha, T. A.; Azab, A. A.

2016-10-01

Borotellurite glasses with formula 60B2O3-10ZnO-(30 - x)NaF- xTeO2 ( x = 0 mol.%, 5 mol.%, 10 mol.%, and 15 mol.%) have been synthesized by thermal melting. X-ray diffraction (XRD) analysis confirmed that the glasses were amorphous. The glass density ( ρ) was determined by the Archimedes method at room temperature. The density ( ρ) and molar volume ( V m) were found to increase with increasing TeO2 content. The direct-current (DC) conductivity was measured in the temperature range from 473 K to 623 K, in which the electrical activation energy of ionic conduction increased from 0.27 eV to 0.48 eV with increasing TeO2 content from 0 mol.% to 15 mol.%. The dielectric parameters and alternating-current (AC) conductivity ( σ ac) were investigated in the frequency range from 1 kHz to 1 MHz and temperature range from 300 K to 633 K. The AC conductivity and dielectric constant decreased with increasing TeO2 content from 0 mol.% to 15 mol.%.

Evolution of ferroelectric SrBi2Nb2O9 phase embedded in tellurite glass

NASA Astrophysics Data System (ADS)

Mohamed, E. A.

2017-12-01

Glasses with the composition, [(100-x)TeO2- x(SrO-Bi2O3-Nb2O5)] with x = 20, 30 and 40 (in mol %) were prepared. The X-ray diffraction (XRD) pattern and differential thermal analysis (DTA) for the as-prepared samples confirmed the amorphous and glassy characteristics, respectively. The SrBi2Nb2O9 phase in tellurite glass for HT773 sample at x = 40 mol % is formed and confirmed by the Rietveld refinement. DTA curves for all glass samples exhibit two endothermic dips while the two broad exothermic peaks at lower x reduced to one at higher x. Infrared (IR) results revealed that the glassy matrix are composed of TeO3, TeO3+1, TeO4, BiO6 and NbO6 structural units. The changes in the density (ρ), molar volume (Vm), oxygen molar volume (V0) and oxygen packing fraction (OPD) have correlated with structural changes in the glass network. The optical studies show an absorption bands below the absorption edge in the glass samples.

Optical Carry Adder.

DTIC Science & Technology

1987-03-01

AOM’s) with the deflected beam as the modulator "on" state. These AOM’s ( TeO2 crystals, manufactured by Newport E.O. Systems) have high deflection...caused by the slow acoustic propagation (4.2 - 105 cm/s for TeO2 ), but this delay can be minimized by placing the laser beam close to the acoustic...dependent jitter in the optical carry to below 1 ns, the total carry path must be less than 30 cm long (or 20 cm in glass , 14 cm in LiNbO 3). Thus, a 32

Criteria for Selection of Graded Index Filter Materials Based on an Analysis of Wave Propagation in a Periodic Medium.

DTIC Science & Technology

1986-01-01

at 579.1 nm. These materials have high dispersion. 96 TABLE 14 OXIDES IN TELLEJRITE GLASSES .- Add it ive n TeO 2 -BaO TeO2 Wo 3 %*- La 2O 3 1.63...13 PbDeO3 and PbSiO 3 96 14 Oxides in Tellurite Glasses 97 15 Wurtzite Structure 98 16 Rocksalt Structure Chalcogenides 99 17 Zincblende or Sphalerite...alumina in glasses , SiO 2, was reported by Zuther, et al. who studied the glass system Ga 203-GeO 2-’v1 O5.56 The refractive indices of the monoclinic

Significance of methicillin-teicoplanin resistant Staphylococcus haemolyticus in bloodstream infections in patients of the Semmelweis University hospitals in Hungary.

PubMed

Kristóf, K; Kocsis, E; Szabó, D; Kardos, S; Cser, V; Nagy, K; Hermann, P; Rozgonyi, F

2011-05-01

The purpose of this study was to quantify the impact of Staphylococcus haemolyticus in the epidemiology of the blood stream infection (BSI) and to characterize the rates and quantitative levels of resistance to antistaphylococcal drugs. During an eight-year period, 2967 BSIs of the patients hospitalized in different clinical departments of the Semmelweis University, Budapest, Hungary were analyzed. One hundred eighty-four were caused by S. haemolyticus, amounting to 6% of all infections. The antibacterial resistance of S. haemolyticus isolates was investigated by the broth microdilution method, vancomycin agar screen, population analysis profile and PCR for mecA, vanA and vanB genes detection. Epidemiological investigation was processed by determining phenotypic antibiotic resistance patterns and PFGE profiles. Extremely high MIC levels of resistance were obtained to oxacillin, erythromycin, clindamycin, gentamicin and ciprofloxacin. The incidence of teicoplanin reduced susceptibility revealed 32% without possessing either the vanA or vanB gene by the strains. PFGE revealed 56 well-defined genotypes indicating no clonal relationship of the strains. The propensity of S. haemolyticus to acquire resistance and its pathogenic potential in immunocompromised patients, especially among preterm neonates, emphasise the importance of species level identification of coagulase-negative staphylococci and routinely determine the MIC of proper antibacterial agents for these isolates.

Amino acid substitutions in the VanS sensor of the VanA-type vancomycin-resistant Enterococcus strains result in high-level vancomycin resistance and low-level teicoplanin resistance.

PubMed

Hashimoto, Y; Tanimoto, K; Ozawa, Y; Murata, T; Ike, Y

2000-04-15

The vancomycin-resistant enterococci GV1, GV2 and GV3, which were isolated from droppings from broiler farms in Japan have been characterized as VanA-type VRE, which express high-level vancomycin resistance (256 or 512 microg ml(-1), MIC) and low-level teicoplanin resistance (1 or 2 microg ml(-1), MIC). The vancomycin resistances were encoded on plasmids. The vancomycin resistance conjugative plasmid pMG2 was isolated from the GV2 strain. The VanA determinant of pMG2 showed the same genetic organization as that of the VanA genes encoded on the representative transposon Tn1546, which comprises vanRSHAXYZ. The nucleotide sequences of all the genes, except the gene related to the vanS gene on Tn1546, were completely identical to the genes encoded on Tn1546. Three amino acid substitutions in the N-terminal region of the deduced VanS were detected in the nucleotide sequence of vanS encoded on pMG2. There were also three amino acid substitutions in the vanS gene of the GV1 and GV3 strains in the same positions as in the vanS gene of pMG2. Vancomycin induced the increased teicoplanin resistance in these strains.

Antibacterial activities of tellurium nanomaterials.

PubMed

Lin, Zong-Hong; Lee, Chia-Hsin; Chang, Hsin-Yun; Chang, Huan-Tsung

2012-05-01

We prepared four differently shaped Te nanomaterials (NMs) as antibacterial reagents against Escherichia coli. By controlling the concentrations of hydrazine (N(2)H(4)) as reducing agent, NaCl, and temperature, we prepared Te nanowires, nanopencils, nanorices, and nanocubes. These four Te NMs resulted in a live/dead ratio of E. coli cells of less than 0.1, which is smaller than that of Ag nanoparticles. The order of antibacterial activity against E. coli is nanocubes ≈ nanorices > nanopencils ≈ nanowires. This is in good agreement with the concentration order of tellurite (TeO(3)(2-)) ions released from Te NMs in E. coli cells, revealing that TeO(3)(2-) ions account for the antibacterial activity of the four Te NMs. We found that spherical Te nanoparticles (32 nm in diameter) with TeO(3)(2-) ions were formed in the E. coli cells. Compared to Ag nanoparticles that are commonly used as antibacterial reagents, Te NMs have higher antibacterial activity and lower toxicity. Thus, Te NMs hold great practical potential as a new and efficient antibacterial agent. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by sol-gel process

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1990-01-01

Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water:TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, x ray diffraction, surface area and pore size distribution measurements.

Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by the sol-gel process

NASA Technical Reports Server (NTRS)

Bansal, N. P.

1992-01-01

Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water: TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, X-ray diffraction, surface area and pore size distribution measurements.

Correlation between physical properties and ultrasonic relaxation parameters in transition metal tellurite glasses

NASA Astrophysics Data System (ADS)

Abd El-Moneim, A.

2003-07-01

The correlation between activation energy of ultrasonic relaxation process through the temperature range from 140 to 300 K and some physical properties has been investigated in pure TeO 2 and transition metal TeO 2-V 2O 5 and TeO 2-MoO 3 glasses according to Bridge and Patel's theory. The oxygen density (loss centers), number of two-well systems, hopping distance and mechanical relaxation time have been calculated in these glasses from the data of density, bulk modulus and stretching force constant of the glass. It has been found that the acoustic activation energy increased linearly with both the oxygen density and the number of two-well systems. The correlation between the acoustic activation energy and bulk modulus was achieved through the stretching force constant of the network and other structural parameters. Moreover, the experimental values of activation energy (V) agree well with those calculated from an empirical equation presented in this study in the form V=2.9×10 -7 F( F/ K) 3.37, where F is the stretching force constant of the glass and K is the experimental bulk modulus.

The crystal structures of BiTeO 3I, NdTeO 3X (X=Cl, Br) and Bi 5TeO 8.5I 2: some crystal chemistry peculiarities of layered Bi(Ln)Te oxyhalides

NASA Astrophysics Data System (ADS)

Berdonosov, Peter S.; Charkin, Dmitry O.; Kusainova, Ardak M.; Hervoches, Charles H.; Dolgikh, Valeriy A.; Lightfoot, Philip

2000-09-01

Four new layered oxyhalides related to the Sillen family have been prepared and characterized by Rietveld refinement of powder X-ray and neutron diffraction data. BiTeO 3I and NdTeO 3Br both adopt tetragonal symmetry, space group P4/ nmm (for BiTeO 3I, a=4.10811(8), c=27.988(1) Å; NdTeO 3Br, a=4.06603(7), c=26.922(1) Å, at 25°C). The structures are composed of triple and double fluorite-related mixed metal oxide layers separated by single and double halogen layers, in the sequence MTe 2O 5XXMTe 2O 5XM 2O 2X, which may be represented by the symbol X 13X 13X 22, where the subscript signifies the number of halogen layers and the superscript the number of metal sublayers within the fluorite block, by analogy with Sillen's notation. The double fluorite layers are occupied exclusively by Bi, whereas there is an ordered arrangement of Bi/Te within the triple fluorite layers, with Te exclusively occupying the outer sublayers of the block. NdTeO 3Cl adopts an orthorhombically distorted form of this structure type, space group Pmmn, a=4.08096(8), b=4.03441(8), c=25.7582(7) Å at 25°C. Bi 5TeO 8.5I 2 adopts a distorted, non-centrosymmetric version of the simpler X 13 structure type, space group Cmm2, a=5.6878(3), b=5.7230(3), c=9.7260(6) Å, consisting of single halogen layers sandwiched between triple fluorite layers, in which there is partial ordering of the Bi/Te cations.

New magnetic graphene-based inorganic-organic sol-gel hybrid nanocomposite for simultaneous analysis of polar and non-polar organophosphorus pesticides from water samples using solid-phase extraction.

PubMed

Rashidi Nodeh, Hamid; Wan Ibrahim, Wan Aini; Kamboh, Muhammad Afzal; Sanagi, Mohd Marsin

2017-01-01

A new graphene-based tetraethoxysilane-methyltrimethoxysilane sol-gel hybrid magnetic nanocomposite (Fe 3 O 4 @G-TEOS-MTMOS) was synthesised, characterized and successfully applied in magnetic solid-phase extraction (MSPE) for simultaneous analysis of polar and non-polar organophosphorus pesticides from several water samples. The Fe 3 O 4 @G-TEOS-MTMOS nanocomposite was characterized using Fourier transform-infrared spectroscopy, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy and X-ray diffraction. Separation, determination and quantification were achieved using gas chromatography coupled with micro electron capture detector. Adsorption capacity of the sorbent was calculated using Langmuir equation. MSPE was linear in the range 100-1000 pg mL -1 for phosphamidon and dimethoate, and 10-100 pg mL -1 for chlorpyrifos and diazinon, with limit of detection (S/N = 3) of 19.8, 23.7, 1.4 and 2.9 pg mL -1 for phosphamidon, dimethoate, diazinon and chlorpyrifos, respectively. The LODs obtained is well below the maximum residual level (100 pg mL -1 ) as set by European Union for pesticides in drinking water. Acceptable precision (%RSD) was achieved for intra-day (1.3-8.7%, n = 3) and inter-day (7.6-17.8%, n = 15) analyses. Fe 3 O 4 @G-TEOS-MTMOS showed high adsorption capacity (54.4-76.3 mg g -1 ) for the selected OPPs. No pesticide residues were detected in the water samples analysed. Excellent extraction recoveries (83-105%) were obtained for the spiked OPPs from tap, river, lake and sea water samples. The newly synthesised Fe 3 O 4 @G-TEOS-MTMOS showed high potential as adsorbent for OPPs analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fluorescent silica nanoparticles containing covalently bound dyes for reporter, marker, and sensor applications

NASA Astrophysics Data System (ADS)

Patonay, Gabor; Henary, Maged; Chapman, Gala; Emer, Kyle; Crow, Sidney

2016-03-01

Silica nanoparticles have proven to be useful in many bioanalytical and medical applications and have been used in numerous applications during the last decade. Combining the properties of silica nanoparticles and fluorescent dyes that may be used as chemical probes or labels can be relatively easy by simply soaking porous silica nanoparticles in a solution of the dye of interest. Under proper conditions the entrapped dye can stay inside the silica nanoparticle for several hours resulting in a useful probe. In spite of the relative durability of these probes, leaching can still occur. A much better approach is to synthesize silica nanoparticles that have the fluorescent dye covalently attached to the backbone structure of the silica nanoparticle. This can be achieved by using appropriately modified tetraethyl orthosilicate (TEOS) analogues during the silica nanoparticle synthesis. The molar ratio of TEOS and modified TEOS will determine the fluorescent dye load in the silica nanoparticle. Dependent on the chemical stability of the reporting dye either reverse micellar (RM) or Stöber method can be used for silica nanoparticle synthesis. If dye stability allows RM procedure is preferred as it results in a much easier control of the silica nanoparticle reaction itself. Also controlling the size and uniformity of the silica nanoparticles are much easier using RM method. Dependent on the functional groups present in the reporting dye used in preparation of the modified TEOS, the silica nanoparticles can be utilized in many applications such as pH sensor, metal ion sensors, labels, etc. In addition surface activated silica nanoparticles with reactive moieties are also excellent reporters or they can be used as bright fluorescent labels. Many different fluorescent dyes can be used to synthesize silica nanoparticles including visible and NIR dyes. Several bioanalytical applications are discussed including studying amoeba phagocytosis.

Improved selective cholesterol adsorption by molecularly imprinted poly(methacrylic acid)/silica (PMAA-SiO₂) hybrid material synthesized with different molar ratios.

PubMed

Clausen, Débora Nobile; Pires, Igor Matheus Ruiz; Tarley, César Ricardo Teixeira

2014-11-01

The present paper describes the synthesis of molecularly imprinted polymer - poly(methacrylic acid)/silica and reports its performance feasibility with desired adsorption capacity and selectivity for cholesterol extraction. Two imprinted hybrid materials were synthesized at different methacrylic acid (MAA)/tetraethoxysilane (TEOS) molar ratios (6:1 and 1:5) and characterized by FT-IR, TGA, SEM and textural data. Cholesterol adsorption on hybrid materials took place preferably in apolar solvent medium, especially in chloroform. From the kinetic data, the equilibrium time was reached quickly, being 12 and 20 min for the polymers synthesized at MAA/TEOS molar ratio of 6:1 and 1:5, respectively. The pseudo-second-order model provided the best fit for cholesterol adsorption on polymers, confirming the chemical nature of the adsorption process, while the dual-site Langmuir-Freundlich equation presented the best fit to the experimental data, suggesting the existence of two kinds of adsorption sites on both polymers. The maximum adsorption capacities obtained for the polymers synthesized at MAA/TEOS molar ratios of 6:1 and 1:5 were found to be 214.8 and 166.4 mg g(-1), respectively. The results from isotherm data also indicated higher adsorption capacity for both imprinted polymers regarding to corresponding non-imprinted polymers. Nevertheless, taking into account the retention parameters and selectivity of cholesterol in the presence of structurally analogue compounds (5-α-cholestane and 7-dehydrocholesterol), it was observed that the polymer synthesized at the MAA/TEOS molar ratio of 6:1 was much more selective for cholesterol than the one prepared at the ratio of 1:5, thus suggesting that selective binding sites ascribed to the carboxyl group from MAA play a central role in the imprinting effect created on MIP. Copyright © 2014 Elsevier B.V. All rights reserved.

[Study on the preparation and properties of novel silica microporous antireflective coating by sol-gel process].

PubMed

Shang, Meng-Ying; Cao, Lin-Hong; Liu, Miao; Luo, Xuan; Ren, Hong-Bo; Ye, Xin; Tang, Yong-Jian; Jiang, Xiao-Dong

2013-04-01

Silica sol was prepared by acid catalyzed sol-gel process using tetraethylorthosilicate (TEOS) as precursor and dimethyldietoxysilane (DDS) as pore-forming agent. A novel kind of monolayer microporous silica anti-reflective (AR) coating was obtained on K9 glass substrate by dip-coating technique and then heat treated at 500 degrees C. The effects of different DDS/TEOS molar ratios on refractive index, transmittance and hardness were investigated. A positive correlation was found between the transmittance and the DDS/TEOS molar ratio due to the increasing porosity. The maximum transmittance can reach 99.7% with the molar ratio of DDS/TEOS rising to 1 : 1. Meanwhile, the refractive index was found quite close to the ideal value 1.22. Nevertheless, higher molar ratio will lead to a bad film-forming property. On the other hand, the hardness of the coatings decreased with the DDS increasing but still remained more than 2 h when the transmittance reached highest. Besides, these coatings exhibit a well abrasion-resistance and excellent adhesivity. The maximum transmittance was only dropped by 0.071% and 0.112% after abrasion for 500 and 1 000 times respectively. Accelerated corrosion tests indicated that the transmittance of traditional coatings rapidly fell down to the substrate level (-92%) after immersion for 5 min, while the transmittance of our novel coating almost linearly decreased and was kept 93.2% after 56 min. In other words, the environment-resistance of our novel silica AR coating is ten times higher than that of traditional ones. The promotions of the coating performances benefit from its micropore structure (-0. 4 nm) with which water molecule can be effectively prevented. With its high transmittance, good mechanical properties and high environment-resistance, this kind of novel coating has a potential application in the field of solar glass modification to improve its anti-reflective properties.

Optical and spectroscopic study of erbium doped calcium borotellurite glasses

NASA Astrophysics Data System (ADS)

Gomes, J. F.; Lima, A. M. O.; Sandrini, M.; Medina, A. N.; Steimacher, A.; Pedrochi, F.; Barboza, M. J.

2017-04-01

In this study, 10CaF2 - (29.9-0.4x)CaO - (60-0.6x)B2O3 - xTeO2 - 0,1Er2O3 (x = 10, 16, 22, 30 and 50 mol %) glasses were synthesized, and their optical and spectroscopic properties were investigated. X-ray diffraction, density, glass transition temperature (Tg), crystallization temperature (Tx), refraction index, luminescence, radiative lifetime and optical absorption measurements were carried out. Molar volume (Vm), thermal stability (Tx-Tg), electronic polarizability (αm), optical bang gap energy (Eg) and Judd-Ofelt (JO) parameters Ωt (2,4,6) were also calculated. The results are discussed in terms of tellurium oxide content. The increase of TeO2 in the glasses composition increases density, refractive index and electronic polarizability. The optical band gap energy decreases varying from 3.37 to 2.71 eV for the glasses with 10 and 50 mol% of TeO2, respectively. The optical absorption coefficient spectra show characteristic bands of Er3+ ions. Furthermore, these spectra in NIR region show a decrease of hydroxyl groups as a function of TeO2 addition. Luminescence intensity and radiative lifetimes at 1530 nm show an increasing with the TeO2 content. The JO parameters of Er:CaBTeX glasses follow the trend Ω2 > Ω4 > Ω6 and the quality factor values (Ω4/Ω6) were between 1.37 and 3.07. By comparing the measured lifetime with the calculated radiative decay time, quantum efficiency was calculated. The luminescence emission intensity at 1530 nm decreases with the increase of temperature. The lifetime values show a slight trend to decrease with the temperature increase, from 300 to 420 K, for all the samples.

Study of the pluronic-silica interaction in synthesis of mesoporous silica under mild acidic conditions.

PubMed

Sundblom, Andreas; Palmqvist, Anders E C; Holmberg, Krister

2010-02-02

The interaction between silica and poly(ethylene oxide) (PEO) in water may appear trivial and it is generally stated that hydrogen bonding is responsible for the attraction. However, a literature search shows that there is not a consensus with respect to the mechanism behind the attractive interaction. Several papers claim that only hydrogen bonding is not sufficient to explain the binding. The silica-PEO interaction is interesting from an academic perspective and it is also exploited in the preparation of mesoporous silica, a material of considerable current interest. This study concerns the very early stage of synthesis of mesoporous silica under mild acidic conditions, pH 2-5, and the aim is to shed light on the interaction between silica and the PEO-containing structure directing agent. The synthesis comprises two steps. An organic silica source, tetraethylorthosilicate (TEOS), is first hydrolyzed and Pluronic P123, a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer, is subsequently added at different time periods following the hydrolysis of TEOS. It is shown that the interaction between the silica and the Pluronic is dependent both on the temperature and on the time between onset of TEOS hydrolysis and addition of the copolymer. The results show that the interaction is mainly driven by entropy. The effect of the synthesis temperature and of the time between hydrolysis and addition of the copolymer on the final material is also studied. The material with the highest degree of mesoorder was obtained when the reaction was performed at 20 degrees C and the copolymer was added 40 h after the start of TEOS hydrolysis. It is claimed that the reason for the good ordering of the silica is that whereas particle formation under these conditions is fast, the rate of silica condensation is relatively low.

Strategic Sealift for Desert Shield not a Blue Print for the Future

DTIC Science & Technology

1991-06-21

the requirements of the Department of Operations. The contents of this paper reflect our own personal views and are not necessarily endorsed by the...answers without breaching operational security most telephone and personal interviews were held on a non- attributable basis. However, we feel that there...MV is LT Jack Lu:uus. MV !st LT Baldomero Lopez and MV PFC Dwayne T. Williams) commanded by Capt. Charles E. Aaker , USN. also got underway on August

A Unified Approach for Modeling Inelastic Behavior of Structural Metals under Complex Cyclic Loadings.

DTIC Science & Technology

1977-05-01

this report are not to be used for advertising , publication, or promotional purposes. Citat ion of trade names does not constitute an off icial... Vs . Real Materials 3 PLASTIC HYSTERESIS PHENOMENA 12 Observed Transient Phenomena Analysis of Hysteresis Loops Observed Typical Yie ld Range...strain or stress amp litude). Fitr examp le , if varm m uus sited hyshet esis loops produced by the model a me super- Memory Modei Vs . Real Materials

Effect of the MgO on microstructure and optical properties of TAG (Tb3Al5O12) transparent ceramics using hot isostatic pressing

NASA Astrophysics Data System (ADS)

Zhang, Shouyi; Liu, Peng; Xu, Xiaodong; Zhang, Jian

2018-06-01

In this work, the TAG transparent ceramics doped with 0.4 wt.% TEOS and different concentration of MgO were fabricated by a reactive sintering process under vacuum sintering combined with hot isostatic pressing (HIP) treatment. The effect of MgO on the microstructure evolution and optical properties of delivered ceramics were investigated. The results showed that the TAG ceramics doped with 0.4 wt.% TEOS and 0.1 wt.% MgO exhibited the optimum optical transmittance, which can reach about 81% in the visible and near-infrared (NIR) regions. The addition of MgO inhibited the grain growth and accelerated the densification of TAG ceramic at the sintering temperature reached about 1600 °C.

DSC and Raman studies of silver borotellurite glasses

NASA Astrophysics Data System (ADS)

Kaur, Amandeep; Khanna, Atul; Gonzàlez, Fernando

2016-05-01

Silver borotellurite glasses of composition: xAg2O-yB2O3-(100-x-y)TeO2 (x=20-mol%, y = 0, 10, 20 and 30-mol%) were prepared and characterized by density, X-ray diffraction (XRD), differential scanning calorimetry, and Raman spectroscopy. XRD confirmed the amorphous structure of all samples. Density of glasses decreases while the glass transition temperature increases with increase in B2O3 content from 10 to 30-mol%. Raman study shows that coordination number of Te with oxygen decreases steadily from 3.42 to 3.18 on adding B2O3 due to the transformation of TeO4 into TeO3 units.

Green synthesis and characterization of size tunable silica-capped gold core-shell nanoparticles

NASA Astrophysics Data System (ADS)

Wangoo, Nishima; Shekhawat, Gajendra; Wu, Jin-Song; Bhasin, Aman K. K.; Suri, C. R.; Bhasin, K. K.; Dravid, Vinayak

2012-08-01

Silica-coated gold nanoparticles (Au@SiO2) with controlled silica-shell thickness were prepared by a modified Stober's method using 10-nm gold nanoparticles (AuNPs) as seeds. The AuNPs were silica-coated with a sol-gel reaction using tetraethylorthosilicate (TEOS) as a silica source and ammonia as a catalyst. An increase in TEOS concentration resulted in an increase in shell thickness. The NPs were characterized by transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray spectroscopy, scanning near-field ultrasound holography and scanning transmission electron microscopy. The method required no surface modification and the synthesized core shell nanoparticles can be used for various types of biological applications.

Transparent organic/inorganic hybrid sol-gel materials based on perfluorinated polymers and silica

NASA Astrophysics Data System (ADS)

Wojcik, Anna B.; Klein, Lisa C.

1996-01-01

Two types of hybrid gels based on silica and perfluorinated polymers have been prepared. The first type involves a perfluorinated polymer containing acrylate groups. Perfluoropolyether diol diacrylate (PFDA) was functionalized by reacting it with (3-mercapto-propyl) trimethoxysilane by a Michael addition. The resulting silyl derivative (PFDAS) was able to copolymerize with a silica precursor, tetraethylorthosilicate (TEOS), resulting in perfluorinated polymer/silica hybrid gels. For the second type, perfluoroalkylsilane (FAS), vinyltriethoxysilane (VTES), and TEOS were polymerized in one step. In both cases, the gels were transparent, crack-free and water repellent. Since the inorganic and organic components are covalently bonded to each other, these materials can be classified as organic/inorganic copolymers.

Structure and properties of epoxy-siloxane-silica nanocomposite coatings for corrosion protection.

PubMed

Torrico, Ruben F A O; Harb, Samarah V; Trentin, Andressa; Uvida, Mayara C; Pulcinelli, Sandra H; Santilli, Celso V; Hammer, Peter

2018-03-01

The fraction of the silica/siloxane phase is a crucial parameter, which determines the structure and thus the properties of epoxy-siloxane-silica hybrid coatings. A careful adjustment of the colloidal precursor formulation allows tuning the nanostructure towards a highly condensed and cross-linked hybrid nanocomposite, suitable as an efficient anticorrosive coating. Novel epoxy-siloxane-silica hybrids have been prepared through the curing reaction of poly(bisphenol A-co-epichlorohydrin) (DGEBA) with diethyltriamine (DETA) and (3-glycidoxypropyl)methyltriethoxysilane (GPTMS), followed by hydrolytic condensation of tetraethoxysilane (TEOS) and GPTMS. At a constant proportion of the organic phase, the effects of the varying molar proportions of siloxane (GPTMS) and silica (TEOS) on the film properties have been investigated. A detailed structural analysis suggests for intermediate TEOS to GPTMS ratios a structure of highly condensed silica-siloxane domains covalently bonded to the embedding epoxy phase. The homogeneous distribution of the quasi-spherical sub-nonmetric silica-siloxane nodes is in agreement with low surface roughness (<5 nm), observed by atomic force microscopy. This dense nanostructure results in high thermal stability (>300 °C), strong adhesion to steel substrate and excellent barrier property in saline solution, with corrosion resistance in the GΩ cm 2 range. Copyright © 2017 Elsevier Inc. All rights reserved.

The effect of high temperature sol-gel polymerization parameters on the microstructure and properties of hydrophobic phenol-formaldehyde/silica hybrid aerogels.

PubMed

Seraji, Mohamad Mehdi; Sameri, Ghasem; Davarpanah, Jamal; Bahramian, Ahmad Reza

2017-05-01

Phenol-formaldehyde/silica hybrid aerogels with different degree of hydrophobicity were successfully synthesized via high temperature sol-gel polymerization. Tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) were used as precursor and co-precursor of the hydrophobic silica-based phase, respectively. The hydrolysis step of silica based sols were conducted by acid catalyzed reactions and HCl was used as hydrolysis catalyst. The chemical structure of prepared hybrid aerogels was characterized by Fourier Transform Infrared spectroscopy (FT-IR). The effect of MTES/TEOS proportion and catalyst content on the morphology and microstructure of samples were investigated by FE-SEM and C, Si mapping analysis. The acid catalyzed hydrolysis of TEOS and MTES sols leads to formation of a sol with primarily silica particles in the organic-inorganic hybrid sol and varying colloid growth mechanisms were occurred with change in MTES and HCl molar ratio. With the increasing of MTES content, the microstructure of samples changed from uniform colloidal network, core-shell structure to polymeric structure with a huge phase separation. The increasing of HCl mole fraction leads to smaller particle size. Moreover, the shrinkage of samples was decreased and water contact angles of the resulted aerogels were increased from 40 to 156.8° with the increases of MTES content. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of F ions on physical and optical properties of fluorine substituted zinc arsenic tellurite glasses

NASA Astrophysics Data System (ADS)

Kareem Ahmmad, Shaik; kondaul, Edu; Rahman, Syed

2015-02-01

The effect of substitution of fluoride ions for oxide ions on the physical and optical properties of glass system (20-x) ZnO-xZnF2-40As2O3-40TeO2 where x = 0, 4, 8,12,16,20 mole % were investigated. The samples prepared by melt quenching method under controlled condition. The amorphous nature of these glasses was checked by X-ray diffraction technique. The density was measured according to Archimedes principle. The room temperature absorption spectra of all glass samples were determined using UV-Vis-NIR spectrometer. The thermal behaviour, glass transition temperature and stability of glass samples were studied by a differential scanning calorimetric (DSC). The density reduction of present glasses with ZnF2 concentrations may be due to the low density of ZnF2 compared with that of ZnO. Breaking the oxide network, the cross linking degree of the glass former could be reduced which results in decrease of both Tg and Tx. In the present glass system when F ions replaced by oxygen ions UV-Vis absorption cut-off wavelength decreases. This resulted form the conversion of structural unit in the glass from TeO4 to Te(O,F)4 and then to Te(O, F)3.

Fiber optic sensors based on hybrid phenyl-silica xerogel films to detect n-hexane: determination of the isosteric enthalpy of adsorption.

PubMed

Echeverría, Jesús C; Calleja, Ignacio; Moriones, Paula; Garrido, Julián J

2017-01-01

We investigated the response of three fiber optic sensing elements prepared at pH 10 from phenyltriethoxysilane (PhTEOS) and tetraethylsilane (TEOS) mixtures with 30, 40, and 50% PhTEOS in the silicon precursor mixture. The sensing elements are referred to as Ph30, Ph40 and Ph50, respectively. The films were synthesized by the sol-gel method and affixed to the end of optical fibers by the dip-coating technique. Fourier transform infrared spectroscopy, N 2 adsorption-desorption at 77 K and X-ray diffraction analysis were used to characterize the xerogels. At a given pressure of n -hexane, the response of each sensing element decreased with temperature, indicating an exothermic process that confirmed the role of adsorption in the overall performance of the sensing elements. The isosteric adsorption enthalpies were obtained from the calibration curves at different temperatures. The magnitude of the isosteric enthalpy of n -hexane increased with the relative response and reached a plateau that stabilized at approximately -31 kJ mol -1 for Ph40 and Ph50 and at approximately -37 kJ mol -1 for Ph30. This indicates that the adsorbate-adsorbent interaction was dominant at lower relative pressure and condensation of the adsorbate on the mesopores was dominant at higher relative pressure.

Survey of Virulence Determinants among Vancomycin Resistant Enterococcus faecalis and Enterococcus faecium Isolated from Clinical Specimens of Hospitalized Patients of North west of Iran

PubMed Central

Sharifi, Yaeghob; Hasani, Alka; Ghotaslou, Reza; Varshochi, Mojtaba; Hasani, Akbar; Aghazadeh, Mohammad; Milani, Morteza

2012-01-01

Recent data indicates an increasing rate of vancomycin resistance in clinical enterococcal isolates worldwide. The nosocomial enterococci are likely to harbor virulence elements that increase their ability to colonize hospitalized patients. The aim of this study was to characterize virulence determinants in vancomycin-resistant enterococci (VRE) obtained from various clinical sources. During the years 2008 to 2010, a total of 48 VRE isolates were obtained from three University teaching hospitals in Northwest, Iran. Initially, phenotypic speciation was done and minimum inhibitory concentrations (MICs) of vancomycin were determined by agar dilution method and E-test. Then, species identification and resistance genotypes along with detection of virulence genes (asa1, esp, gelE, ace and cpd) of the isolates were performed by multiplex PCR. Thirty eight isolates were identified as vancomycin-resistant Enterococcus faecium (VREfm) and ten as E. faecalis (VREfs). Irrespective of the species, vanA gene (89.58%) was dominant and three phenotypically vancomycin susceptible E. faecium isolates carried the vanB gene. Among virulence genes investigated, the esp was found in 27(71%) VREfm strains, but did not in any VREfs. Other virulence determinants were highly detected in VREfs strains. Our data indicate a high prevalence of E. faecium harboring vancomycin resistance with vanA genotype and the two VRE species displayed different virulence genes. PMID:22582098

Prevalence of antibiotic resistance genes in bacterial communities associated with Cladophora glomerata mats along the nearshore of Lake Ontario.

PubMed

Ibsen, Michael; Fernando, Dinesh M; Kumar, Ayush; Kirkwood, Andrea E

2017-05-01

The alga Cladophora glomerata can erupt in nuisance blooms throughout the lower Great Lakes. Since bacterial abundance increases with the emergence and decay of Cladophora, we investigated the prevalence of antibiotic resistance (ABR) in Cladophora-associated bacterial communities up-gradient and down-gradient from a large sewage treatment plant (STP) on Lake Ontario. Although STPs are well-known sources of ABR, we also expected detectable ABR from up-gradient wetland communities, since they receive surface run-off from urban and agricultural sources. Statistically significant differences in aquatic bacterial abundance and ABR were found between down-gradient beach samples and up-gradient coastal wetland samples (ANOVA, Holm-Sidak test, p < 0.05). Decaying and free-floating Cladophora sampled near the STP had the highest bacterial densities overall, including on ampicillin- and vancomycin-treated plates. However, quantitative polymerase chain reaction analysis of the ABR genes ampC, tetA, tetB, and vanA from environmental communities showed a different pattern. Some of the highest ABR gene levels occurred at the 2 coastal wetland sites (vanA). Overall, bacterial ABR profiles from environmental samples were distinguishable between living and decaying Cladophora, inferring that Cladophora may control bacterial ABR depending on its life-cycle stage. Our results also show how spatially and temporally dynamic ABR is in nearshore aquatic bacteria, which warrants further research.

In Situ Antibacterial Activity of Essential Oils with and without Alcohol on Oral Biofilm: A Randomized Clinical Trial

PubMed Central

Quintas, Victor; Prada-López, Isabel; Carreira, María J.; Suárez-Quintanilla, David; Balsa-Castro, Carlos; Tomás, Inmaculada

2017-01-01

Currently, there is little evidence on the in situ antibacterial activity of essential oils (EO) without alcohol. This study aimed to evaluate in situ the substantivity and antiplaque effect on the plaque-like biofilm (PL-biofilm) of two solutions, a traditional formulation that contains EO with alcohol (T-EO) and an alcohol-free formulation of EO (Af-EO). Eighteen healthy adults performed a single mouthwash of: T-EO, Af-EO, and sterile water (WATER) after wearing an individualized disk-holding splint for 2 days. The bacterial viability (BV) and thickness of the PL-biofilm were quantified at baseline, 30 s, and 1, 3, 5, and 7 h post-rinsing (Test 1). Subsequently, each volunteer wore the splint for 4 days, applying two daily mouthwashes of: T-EO, Af-EO, and WATER. The BV, thickness, and covering grade (CG) of the PL-biofilm were quantified (Test 2). Samples were analyzed by confocal laser scanning microscopy after staining with the LIVE/DEAD® BacLight™ solution. To conduct the computations of the BV automatically, a Matlab toolbox called Dentius Biofilm was developed. In test 1, both EO antiseptics had a similar antibacterial effect, reducing BV after a single rinse compared to the WATER, and keeping it below baseline levels up to 7 h post-rinse (P < 0.001). The mean thickness of the PL-biofilm after rinsing was not affected by any of the EO formulations and ranged from 18.58 to 20.19 μm. After 4 days, the T-EO and Af-EO solutions were significantly more effective than the WATER, reducing the BV, thickness, and CG of the PL-biofilm (P < 0.001). Although, both EO antiseptics presented a similar bactericidal activity, the Af-EO rinses led to more significant reductions in the thickness and CG of the PL-biofilm than the T-EO rinses (thickness = 7.90 vs. 9.92 μm, P = 0.012; CG = 33.36 vs. 46.61%, P = 0.001). In conclusion, both essential oils antiseptics had very high immediate antibacterial activity and substantivity in situ on the 2-day PL-biofilm after a single

Highly dispersed SiO x/Al 2O 3 catalysts illuminate the reactivity of isolated silanol sites

DOE PAGES

Mouat, Aidan R.; George, Cassandra; Kobayashi, Takeshi; ...

2015-09-23

The reaction of γ-alumina with tetraethylorthosilicate (TEOS) vapor at low temperatures selectively yields monomeric SiO x species on the alumina surface. These isolated (-AlO) 3Si(OH) sites are characterized by PXRD, XPS, DRIFTS of adsorbed NH 3, CO, and pyridine, and 29Si and 27Al DNP-enhanced solid-state NMR spectroscopy. The formation of isolated sites suggests that TEOS reacts preferentially at strong Lewis acid sites on the γ-Al 2O 3 surface, functionalizing the surface with “mild” Brønsted acid sites. As a result, for liquid-phase catalytic cyclohexanol dehydration, these SiO x sites exhibit up to 3.5-fold higher specific activity than the parent alumina withmore » identical selectivity.« less

Response Surface Methodology for Design of Porous Hollow Sphere Thermal Insulator

NASA Astrophysics Data System (ADS)

Shohani, Nazanin; Pourmahdian, Saeed; Shirkavand Hadavand, Behzad

2017-11-01

In this study, response surface method is used for synthesizing polystyrene (PS) as sacrificial templates and optimizing the particle size. Three factors of initiator, stabilizer concentration and also stirring rate were selected as variable factors. Then, three different concentration of tetraethyl orthosilicate (TEOS) added to reaction media and core-shell structure with PS core and silica shell was developed. Finally, core-shell structure was changed to hollow silica sphere for using as thermal insulator. We observed that increased initiator concentration caused to larger PS particles, increase the stirring rate caused the smaller PS and also with increased the stabilizer concentration obtained that particle size decrease then after 2.5% began to increase. Also the optimum amount of TEOS was found.

[Emergence of glycopeptide resistant Enterococcus faecium in Algeria: a case report].

PubMed

Hamidi, Moufida; Ammari, Houria; Ghaffor, Mohamed; Benamrouche, Nabila; Tali-Maamar, Hassiba; Tala-Khir, Farida; Younsi, Mokhtar; Rahal, Kheira

2013-01-01

A glycopeptide-resistant Enterococcus faecium (EFRG) was isolated from a wound in a patient hospitalized in a university hospital in Algiers. This strain was resistant to several antibiotics. This patient was carrying this strain in the digestive tract which may partly explain its origin. Genotypic comparison of the two strains by pulsed field gel electrophoresis showed that it was the same strain. Glycopeptide resistance was due to the presence of the vanA gene. Vigilance is required facing the emergence of strains of EFRG in our hospitals.

Development of Octyl Methoxy Cinnamates (OMC)/Silicon Dioxide (SiO₂) Nanoparticles by Sol-Gel Emulsion Method.

PubMed

Wu, Pey-Shiuan; Lee, Yi-Ching; Kuo, Yi-Ching; Lin, Chih-Chien

2017-12-07

Although octyl methoxy cinnamates (OMC) is the most used Ultraviolet B (UVB) filter in sunscreen, it has poor light stability in emulsion system. In this study, OMC/SiO₂ nanoparticles were prepared via sol-gel emulsion method. Tetraethoxy silane (TEOS) was used as the silica source to encapsulate OMC. Modification of experimental parameters such as stirring speed of condensation reaction and emulsion condition, pH value of acid-catalyzed, surfactant and different percentage of TEOS and OMC, adding of OMC and surfactant to different phase may affect the particle size, and yield and entrapment efficiency in preparation process of OMC/SiO₂ nanoparticles. Concluding all the parameter, we found that when condensation reaction and emulsion conditions are at 1000 rpm, pH 1.5, Span 80/Tween 20, TEOS/OMC ratios 1:1, OMC and surfactants added in oil phase, resulting in smaller particle sizes 476.5 nm, higher yield 95.8%, and higher entrapment efficiency 61.09%. Fourier transform infrared (FTIR) analysis demonstrated that OMC/SiO₂ nanoparticles were successfully prepared. In vitro release profile supposed that OMC/SiO₂ nanoparticles can delay OMC releasing and had 60.83% decreasing of cumulative amount. Therefore, the OMC/SiO₂ nanoparticles have the potential to develop as new sunscreen materials in the use for cosmetics field in the future.

Role of lithium ions on the physical, structural and optical properties of zinc boro tellurite glasses

NASA Astrophysics Data System (ADS)

Rani, S.; Ahlawat, N.; Parmar, R.; Dhankhar, S.; Kundu, R. S.

2018-07-01

Lithium zinc boro tellurite glasses with compositions xLi2O-(100-x) [0.25ZnO-0.15B2O3-0.60TeO2] [where x = 0, 5, 10, 15 and 20 mol%] have been prepared by melt-quench technique. The amorphous nature of the prepared system is ascertained by X-ray diffraction. The density and molar volume are found to decrease with the increase in concentration of Li2O. The differential scanning calorimetry is used to calculate the glass transition temperature (Tg) and the observed values are found to be decreased. The IR and Raman spectra indicate that Li2O acts as a network modifier in the glass matrix. In the present system, tellurium exists as TeO4 and TeO3, B2O3 in the form of BO4 and BO3 and zinc oxide exists as ZnO4 structural units. The values of the optical band gap are estimated from the fitting of Mott and Davis's and model. A better convergence is achieved between experimental observed spectra of absorption coefficient and hydrogenic excitonic model. The optical band gap energy increases, whereas refractive index and molar refractivity follow the reverse trend with Li2O. The range of metallization criterion suggests that these glasses may be a potential candidate for nonlinear optical materials.

Fiber optic sensors based on hybrid phenyl-silica xerogel films to detect n-hexane: determination of the isosteric enthalpy of adsorption

PubMed Central

Calleja, Ignacio; Moriones, Paula; Garrido, Julián J

2017-01-01

We investigated the response of three fiber optic sensing elements prepared at pH 10 from phenyltriethoxysilane (PhTEOS) and tetraethylsilane (TEOS) mixtures with 30, 40, and 50% PhTEOS in the silicon precursor mixture. The sensing elements are referred to as Ph30, Ph40 and Ph50, respectively. The films were synthesized by the sol–gel method and affixed to the end of optical fibers by the dip-coating technique. Fourier transform infrared spectroscopy, N2 adsorption–desorption at 77 K and X-ray diffraction analysis were used to characterize the xerogels. At a given pressure of n-hexane, the response of each sensing element decreased with temperature, indicating an exothermic process that confirmed the role of adsorption in the overall performance of the sensing elements. The isosteric adsorption enthalpies were obtained from the calibration curves at different temperatures. The magnitude of the isosteric enthalpy of n-hexane increased with the relative response and reached a plateau that stabilized at approximately −31 kJ mol−1 for Ph40 and Ph50 and at approximately −37 kJ mol−1 for Ph30. This indicates that the adsorbate–adsorbent interaction was dominant at lower relative pressure and condensation of the adsorbate on the mesopores was dominant at higher relative pressure. PMID:28326238

Role of lithium ions on the physical, structural and optical properties of zinc boro tellurite glasses

NASA Astrophysics Data System (ADS)

Rani, S.; Ahlawat, N.; Parmar, R.; Dhankhar, S.; Kundu, R. S.

2018-01-01

Lithium zinc boro tellurite glasses with compositions xLi2O-(100-x) [0.25ZnO-0.15B2O3-0.60TeO2] [where x = 0, 5, 10, 15 and 20 mol%] have been prepared by melt-quench technique. The amorphous nature of the prepared system is ascertained by X-ray diffraction. The density and molar volume are found to decrease with the increase in concentration of Li2O. The differential scanning calorimetry is used to calculate the glass transition temperature (Tg) and the observed values are found to be decreased. The IR and Raman spectra indicate that Li2O acts as a network modifier in the glass matrix. In the present system, tellurium exists as TeO4 and TeO3, B2O3 in the form of BO4 and BO3 and zinc oxide exists as ZnO4 structural units. The values of the optical band gap are estimated from the fitting of Mott and Davis's and model. A better convergence is achieved between experimental observed spectra of absorption coefficient and hydrogenic excitonic model. The optical band gap energy increases, whereas refractive index and molar refractivity follow the reverse trend with Li2O. The range of metallization criterion suggests that these glasses may be a potential candidate for nonlinear optical materials.

Representation of Time-Relevant Common Data Elements in the Cancer Data Standards Repository: Statistical Evaluation of an Ontological Approach

PubMed Central

Chen, Henry W; Du, Jingcheng; Song, Hsing-Yi; Liu, Xiangyu; Jiang, Guoqian

2018-01-01

Background Today, there is an increasing need to centralize and standardize electronic health data within clinical research as the volume of data continues to balloon. Domain-specific common data elements (CDEs) are emerging as a standard approach to clinical research data capturing and reporting. Recent efforts to standardize clinical study CDEs have been of great benefit in facilitating data integration and data sharing. The importance of the temporal dimension of clinical research studies has been well recognized; however, very few studies have focused on the formal representation of temporal constraints and temporal relationships within clinical research data in the biomedical research community. In particular, temporal information can be extremely powerful to enable high-quality cancer research. Objective The objective of the study was to develop and evaluate an ontological approach to represent the temporal aspects of cancer study CDEs. Methods We used CDEs recorded in the National Cancer Institute (NCI) Cancer Data Standards Repository (caDSR) and created a CDE parser to extract time-relevant CDEs from the caDSR. Using the Web Ontology Language (OWL)–based Time Event Ontology (TEO), we manually derived representative patterns to semantically model the temporal components of the CDEs using an observing set of randomly selected time-related CDEs (n=600) to create a set of TEO ontological representation patterns. In evaluating TEO’s ability to represent the temporal components of the CDEs, this set of representation patterns was tested against two test sets of randomly selected time-related CDEs (n=425). Results It was found that 94.2% (801/850) of the CDEs in the test sets could be represented by the TEO representation patterns. Conclusions In conclusion, TEO is a good ontological model for representing the temporal components of the CDEs recorded in caDSR. Our representative model can harness the Semantic Web reasoning and inferencing functionalities and

One-year surveillance of ESKAPE pathogens in an intensive care unit of Monterrey, Mexico.

PubMed

Llaca-Díaz, Jorge Martín; Mendoza-Olazarán, Soraya; Camacho-Ortiz, Adrian; Flores, Samantha; Garza-González, Elvira

2012-01-01

Bacterial species from the ESKAPE group (i.e. Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter species) are frequently resistant to antibiotics. The purpose of this study was to monitor the incidence of ESKAPE pathogens at the intensive care unit (ICU) of a tertiary care hospital in Monterrey, Mexico. All clinically relevant organisms isolated from June 2011 to June 2012 were included. Identification and susceptibility testing was performed using panels from Sensititre. Resistance to oxacillin, for S. aureus, and the production of extended spectrum β-lactamases (ESBLs), for K. pneumonia, were determined as defined by the Clinical Laboratory Standards Institute. Also, the presence of vanA and vanB genes was determined in E. faecium vancomycin (VAN)-resistant isolates. The majority of pathogens (64.5%) isolated in the ICU unit were from the ESKAPE group. The organisms most frequently isolated were A. baumannii (15.8%) and P. aeruginosa (14.3%). A high resistance to carbapenems was detected for A. baumannii (75.3%) while 62% of S. aureus isolates were confirmed to be methicillin resistant. Of the K. pneumoniae isolates, 36.9% were ESBL producers. We detected three E. faecium VAN-resistant isolates, all of which contained the vanA gene. The presence of the ESKAPE group of pathogens is a major problem in the ICU setting. The results of this study support the implementation of special antimicrobial strategies to specifically target these microorganisms. Copyright © 2013 S. Karger AG, Basel.

A prism of excellence: The Charleston Veterans Administration Nursing Academic Partnership.

PubMed

Coxe, D Nicole; Conner, Brian T; Lauerer, Joy; Skipper, Janice; York, Janet; Fraggos, Mary; Stuart, Gail W

2016-01-01

The Veterans Administration (VA) has been committed to academic affiliate training partnerships for nearly 70 years in efforts to enhance veteran-centric health care. One such effort, the VA Nursing Academy (VANA) program, was developed in 2007 in response to the nationwide nursing shortage and began as a five-year pilot with funding competitively awarded to 15 partnerships between local VA medical centers and schools of nursing. The VANA program evolved into the VA Nursing Academic Partnership (VANAP) program following the initial pilot. This article describes the development and evolution of the Charleston VANAP, which includes the Ralph H Johnson VA Medical Center (RHJ VAMC) and the Medical University of South Carolina College of Nursing (MUSC CON). The VA Office of Academic Affiliations (OAA) funded a large portion of the initial five years of the Charleston VANAP. Once the national funding source ceased, the RHJ VAMC and the MUSC CON entered into a Memorandum of Understanding (MOU) to offer in-kind contributions to the partnership. The Charleston VANAP is the only program in the nation to offer three different nurse trainee programs and this article highlights some of the more notable achievements from each program. The Charleston VANAP is a comprehensive partnership between the RHJ VAMC and the MUSC CON that truly demonstrates a commitment to assure that the very best care be provided to Veterans, our Nation's heroes. Copyright © 2016 Elsevier Inc. All rights reserved.

Clinical and molecular epidemiology of hospital Enterococcus faecium isolates in eastern France. Members of Réseau Franc-Comtois de Lutte contr les Infections Nosocomiales.

PubMed

Bertrand, X; Thouverez, M; Bailly, P; Cornette, C; Talon, D

2000-06-01

We carried out a surveillance study of Enterococcus faecium isolates in the Franche-Comtéregion of France over three years. Clinical and epidemiological strains were characterized by antibiotype and genotype (pulsed field gel electrophoresis, PFGE). Three case-control studies were performed to identify risk factors for colonization/infection with three defined resistant phenotypes (amoxycillin, high-level gentamicin and high-level kanamycin). The crude incidence of colonization/infection was 0.156%, and 68.8% of cases were classified as hospital-acquired. Incidence did not differ according to the type of hospitalization (middle term or acute care). The urinary tract was the major site of infection. Resistance rates were: 45.8% (amoxycillin), 18.7% (high-level gentamicin), 61.4% (high-level kanamycin) and 3.1% (vancomycin). No isolate produced b-lactamase and one isolate carried the vanA gene. PFGE revealed two major epidemic patterns each including resistant strains isolated in different hospitals and during different periods in the study. Previous antimicrobial treatment was not identified as a risk factor for colonization/infection with any resistant phenotype. Despite the low frequency of vancomycin-resistant isolates in this study, resistant strains were widely disseminated and had characteristics enabling them to persist and spread. If these strains acquired the vanA gene, the risk of an outbreak would be large. So, the prevalence of vancomycin-resistant E. faecium in hospitals should be carefully monitored in the future. Copyright 2000 The Hospital Infection Society.

The LPA1/ZEB1/miR-21-activation pathway regulates metastasis in basal breast cancer.

PubMed

Sahay, Debashish; Leblanc, Raphael; Grunewald, Thomas G P; Ambatipudi, Srikant; Ribeiro, Johnny; Clézardin, Philippe; Peyruchaud, Olivier

2015-08-21

Lysophosphatidic acid (LPA) is a bioactive lipid promoting cancer metastasis. LPA activates a series of six G protein-coupled receptors (LPA1-6). While blockage of LPA1in vivo inhibits breast carcinoma metastasis, down-stream genes mediating LPA-induced metastasis have not been yet identified. Herein we showed by analyzing publicly available expression data from 1488 human primary breast tumors that the gene encoding the transcription factor ZEB1 was the most correlated with LPAR1 encoding LPA1. This correlation was most prominent in basal primary breast carcinomas and restricted to cell lines of basal subtypes. Functional experiments in three different basal cell lines revealed that LPA-induced ZEB1 expression was regulated by the LPA1/Phosphatidylinositol-3-Kinase (Pi3K) axis. DNA microarray and real-time PCR analyses further demonstrated that LPA up-regulated the oncomiR miR-21 through an LPA1/Pi3K/ZEB1-dependent mechanism. Strikingly, treatment with a mirVana miR-21 inhibitor, or silencing LPA1 or ZEB1 completely blocked LPA-induced cell migration in vitro, invasion and tumor cell bone colonization in vivo, which can be restored with a mirVana miR-21 mimic. Finally, high LPAR1 expression in basal breast tumors predicted worse lung-metastasis-free survival. Collectively, our results elucidate a new molecular pathway driving LPA-induced metastasis, thus underscoring the therapeutic potential of targeting LPA1 in patients with basal breast carcinomas.

Antimicrobial Resistance Genes in Pigeons from Public Parks in Costa Rica.

PubMed

Blanco-Peña, K; Esperón, F; Torres-Mejía, A M; de la Torre, A; de la Cruz, E; Jiménez-Soto, M

2017-11-01

Antimicrobial resistance is known to be an emerging problem, but the extent of the issue remains incomplete. The aim of this study was to determine the presence or absence of nine resistance genes (bla TEM , catI, mecA, qnrS, sulI, sulII, tet(A), tet(Q), vanA) in the faeces of 141 pigeons from four urban parks in Alajuela, Guadalupe, Tres Ríos and San José in Costa Rica. The genes were identified by real-time PCR directly from enema samples. About 30% of the samples were positive for genes catI and sulI; between 13% and 17% were positive for qnrS, sulII, tet(A) and tet(Q); and 4% were positive for bla TEM . The mecA and vanA genes were not detected. The average of antimicrobial resistance genes detected per pigeon was 2. Eight different patterns of resistance were identified, without differences in the sampling areas, being the most common pattern 2 (sulII positive samples). During rainy season, the genes more frequently found were sulI and tet(A). In conclusion, the urban inhabiting pigeons tested are currently carrying antimicrobial resistance genes, potentially acting as reservoirs of resistant bacteria and vectors to humans. To the authors' knowledge, this is the first study carried out on direct detection of resistance genes in the digestive metagenomes of pigeons. © 2017 The Authors. Zoonoses and Public Health Published by Blackwell Verlag GmbH.

Two-tier approach combining molecular and culture-based techniques for optimized detection of vancomycin-resistant enterococci.

PubMed

Both, Anna; Franke, Gefion C; Mirwald, Nadine; Lütgehetmann, Marc; Christner, Martin; Klupp, Eva-Maria; Belmar Campos, Cristina; Büttner, Henning; Aepfelbacher, Martin; Rohde, Holger

2017-12-01

Given constantly high or even rising incidences of both colonization and infection with vancomycin-resistant enterococci (VRE), timely and accurate identification of carriers in high-risk patient populations is of evident clinical importance. In this study, a two-tier approach consisting of PCR-based screening and cultural confirmation of positive results is compared to the conventional approach solely based on culture on selective media. The 2-tier strategy was highly consistent with the conventional approach, and was found to possess high sensitivity and specificity (93.1% and 100%, respectively). The introduction of the PCR-based combined VRE screening approach significantly (P<0.0001) reduced median overall time to result by 44.3hours. The effect was found to be most pronounced in VRE negative samples. Positive vanA PCR was highly consistent with culture (PPV: 92.0%, 95% CI: 72.5-98.6%, NPV: 99.6%, 95% CI: 98.9-99.6%), thus allowing for preliminary reporting of VRE detection. In contrast, a vanB positive PCR does not allow for preliminary reporting (PPV: 58.5%, 95% CI: 44.2-71.6%, NPV: 99.8%, 95% CI: 99.2-100%). The introduction of a molecular assay for rapid detection of VRE from rectal swabs combined with cultural confirmation proved to be reliable and time saving, especially in a setting of low VRE prevalence and predominance of vanA positive strains. Copyright © 2017 Elsevier Inc. All rights reserved.

Polymeric composites on the basis of Martian ground for building future mars stations

NASA Astrophysics Data System (ADS)

Mukbaniani, O. V.; Aneli, J. N.; Markarashvili, E. G.; Tarasashvili, M. V.; Aleksidze, N. D.

2016-04-01

The colonization of Mars will require obtaining building materials which can be put in place and processed into buildings via various constructive technologies. We tried to use artificial Martian ground - AMG (GEO PAT 11-234 (2015)) and special resins for the preparation of building block prototypes. The composite material has been obtained based on the AMG as filler, epoxy resin (type ED-20) and tetraethoxysilane - TEOS. We have studied strengthening - softening temperatures and water absorption of the AMG polymer composites that are determined by epoxy resin and TEOS modification. Comparison of the experimental results shows that composites containing modified filler have higher values of the maximum ultimate strength, resistance and flexibility parameters than unmodified composites with definite loading. Modified composites also have a higher softening temperature and lower water absorption.

Raman scattering in tellurium-metal oxyde glasses

NASA Astrophysics Data System (ADS)

Mazzuca, M.; Portier, J.; Tanguy, B.; Romain, F.; Fadli, A.; Turrell, S.

1995-04-01

Structural studies were undertaken of glasses in the (1-x)TeO 2 - xZnO system. The glass domain (0,09 < x > 0,40) was verified and variations observed in the Raman spectra were correlated with changes induced on the TeO 2 polyhedra upon glass formation with the addition of the metal oxyde. Spectra were recorded as these glasses were heated through T C and recrystallized. The spectral profiles observed in the recrystallized systems closely resemble those of the broad bands in the initial glasses. The sharp bands in the final spectra, characteristic of a more ordered phase, are interpreted (by correlation with neutron diffraction data) on the basis of chains of TeO 3TeO 4 polyhedra interlaced with chains of ZnO 6 groups.

Acousto-Optic Adaptive Processing (AOAP).

DTIC Science & Technology

1983-12-01

2.03 mm 136 mm 41.6 mm Dense Flint Glass .58 1.06 48.6 21.7 LiNbO3 .65 2.24 250 46 1011 1 -: PbMoO4 .207 1.25 84.3 25.3 .- Slow Shear TeO2 .0586...mm 41.6 m Dense Flint Glass 5.9 1.06 3.2 21.7 LiNbO3 6.6 2.24 16.3 46 PbMoO4 2.1 1.25 5.5 25.6 TeO2 ’" ’" (slow,•...: Shear) 0.59 0.21 0.15 4.32 It is...was observed. 3.1.3 Delay Line The delay line used for the initial experiment is an Isomet Type 1201 AO modulator. This is a glass unit operat- ing at

Distributed Heterogeneous Simulation of a Hybrid-Electric Vehicle

DTIC Science & Technology

2006-03-29

voltage dc bus via a fully controlled three-phase bridge converter. Also connc·:[uJ iu tilL UUS are the Lithium - ion battery bank, the ultra-capacitor...s~b~;~~~~·3 .... ! Lithium - Ion Battery Storage I _ .. ~:; Low-voltage Bus i I I] j i DC~ Converter ! -~~- ti~! 1 I --Ii! Battery i...devices in the propulsion system include the lithium - ion battery bank and the ultra-capacitor. Based on the range of the vehicle in the stealth model

Preparation of Copper Telluride Films by Co-Reduction of Cu(I) and Te(IV) Ions in Choline Chloride: Ethylene Glycol Ionic Liquid

NASA Astrophysics Data System (ADS)

Golgovici, Florentina; Catrangiu, Adriana-Simona; Stoian, Andrei Bogdan; Anicai, Liana; Visan, Teodor

2016-07-01

Cathodic processes of direct co-reduction of Cu+ and Te4+ ions on Pt electrode at 60°C were investigated using cyclic voltammetry and electrochemical impedance spectroscopy techniques. The ionic liquid as background electrolyte consisted of a mixture of choline chloride and ethylene glycol (ChCl-EG 1:2 mol ratio) in which 5-20 mM CuCl and 8 mM TeO2 were dissolved. The voltammograms exhibited the following successive cathodic processes: Cu2+/Cu+ reduction, Te underpotential deposition, simultaneous deposition of Cu metal and CuTe compound, and deposition of Te-rich CuTe compound at the most negative potentials (from -0.5 V to -0.8 V). Corresponding dissolution or oxidation peaks were recorded on the anodic branch. The voltammetric results were confirmed by electrochemical impedance spectra. Copper telluride films have been synthesized on platinum substrate via potentiostatic electrodeposition at 60°C. It was found from atomic force microscopy that CuTe film samples prepared from ChCl-EG + 5 mM CuCl + 8 mM TeO2 ionic liquid have high growth rates. The x-ray diffraction patterns of the deposited films from ChCl-EG + 10 mM CuCl + 8 mM TeO2 ionic liquid indicated the presence of a Cu2Te phase for film deposited at -0.7 V and a Cu0.656Te0.344 phase for film deposited at -0.6 V.

Influence of several metal ions on the gelation activation energy of silicon tetraethoxide

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1988-01-01

The effects of nine metal cations (Li(+), Na(+), Mg(2+), Ca(2+), Sr(2+), Cu(2+), Al(3+), La(3+), and Y(3+) on silica gel formation has been investigated by studying the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) in the presence of metal nitrates. The influence of water: TEOS mole ratio, metal ion concentration, and the reaction temperature has been investigated. The overall activation energy for gel formation has been determined from the temperature dependence of the time of gelation for each system. The activation energy for -Si-O-Si- network formation is found to be 54.5 kJ/mol. The gel formation time as well as the activation energy sharply increase in the presence of Cu(2+), Al(3+), La(3+) and Y(3+). In contrast, the presence of Li(+), Na(+), Mg(2+), Ca(2+), or, Sr(2+) lowers the gelation time, but has no appreciable effect on the activation energy. This difference may be attributed to the participation or nonparticipation of the metal ions in the formation of the three-dimensional polymeric network during the polycondensation step. The concentration of metal ion (Mg(2+), Ca(2+), Y(3+) or the water: TEOS mole ratio had no appreciable effect on the gelation activation energy. A simple test has been proposed to determine whether a metal ion would act as a network intermediate or modifier in silica and other glassy networks.

Total synthesis of isotopically enriched Si-29 silica NPs as potential spikes for isotope dilution quantification of natural silica NPs.

PubMed

Pálmai, Marcell; Szalay, Roland; Bartczak, Dorota; Varga, Zoltán; Nagy, Lívia Naszályi; Gollwitzer, Christian; Krumrey, Michael; Goenaga-Infante, Heidi

2015-05-01

A new method was developed for the preparation of highly monodisperse isotopically enriched Si-29 silica nanoparticles ((29)Si-silica NPs) with the purpose of using them as spikes for isotope dilution mass spectrometry (IDMS) quantification of silica NPs with natural isotopic distribution. Si-29 tetraethyl orthosilicate ((29)Si-TEOS), the silica precursor was prepared in two steps starting from elementary silicon-29 pellets. In the first step Si-29 silicon tetrachloride ((29)SiCl4) was prepared by heating elementary silicon-29 in chlorine gas stream. By using a multistep cooling system and the dilution of the volatile and moisture-sensitive (29)SiCl4 in carbon tetrachloride as inert medium we managed to reduce product loss caused by evaporation. (29)Si-TEOS was obtained by treating (29)SiCl4 with absolute ethanol. Structural characterisation of (29)Si-TEOS was performed by using (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. For the NP preparation, a basic amino acid catalysis route was used and the resulting NPs were analysed using transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), dynamic light scattering (DLS) and zeta potential measurements. Finally, the feasibility of using enriched NPs for on-line field-flow fractionation coupled with multi-angle light scattering and inductively coupled plasma mass spectrometry (FFF/MALS/ICP-MS) has been demonstrated. Copyright © 2015 Elsevier Inc. All rights reserved.

Silane-based coatings on the pyrite for remediation of acid mine drainage.

PubMed

Diao, Zenghui; Shi, Taihong; Wang, Shizhong; Huang, Xiongfei; Zhang, Tao; Tang, Yetao; Zhang, Xiaying; Qiu, Rongliang

2013-09-01

Acid mine drainage (AMD) resulting from the oxidation of pyrite and other metal sulfides has caused significant environmental problems, including acidification of rivers and streams as well as leaching of toxic metals. With the goal of controlling AMD at the source, we evaluated the potential of tetraethylorthosilicate (TEOS) and n-propyltrimethoxysilane (NPS) coatings to suppress pyrite oxidation. The release of total Fe and SO4(-2) from uncoated and coated pyrite in the presence of a chemical oxidizing agent (H2O2) or iron-oxidizing bacteria (Acidithiobacillus ferrooxidans) was measured. Results showed that TEOS- and NPS-based coatings reduced chemical oxidation of pyrite by as much as 59 and 96% (based on Fe release), respectively, while biological oxidation of pyrite was reduced by 69 and 95%, respectively. These results were attributed to the formation of a dense network of Fe-O-Si and Si-O-Si bonds on the pyrite surface that limited permeation of oxygen, water, and bacteria. Compared with results for TEOS-coated pyrite, higher pH and lower concentrations of total Fe and SO4(-2) were observed for oxidation of NPS-coated pyrite, which was attributed to its crack-free morphology and the presence of hydrophobic groups on the NPS-based coating surface. The silane-based NPS coating was shown to be highly effective in suppressing pyrite oxidation, making it a promising alternative for remediation of AMD at its source. Copyright © 2013 Elsevier Ltd. All rights reserved.

Structure and Chemistry in Halide Lead-Tellurite Glasses

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

McCloy, John S.; Riley, Brian J.; Lipton, Andrew S.

2013-02-11

A series of TeO2-PbO glasses were fabricated with increasing fractions of mixed alkali, alkaline earth, and lanthanide chlorides. The glass and crystal structure was studied with Raman spectroscopy, nuclear magnetic resonance (NMR), X-ray diffraction, and electron microscopy. As the chloride fraction increased, the medium-range order in the glass decreased up to a critical point (~14 mass% of mixed chlorides), above which the glasses became phase-separated. Resulting phases are a TeO2/PbO-rich phase and a crystalline phase rich in alkali chlorides. The 125Te NMR indicates, contrary to previous studies, that Te site distribution did not change with increased concentrations of M+, M2+,more » and M3+ cations, but rather is controlled by the Te/Pb molar ratio. The 207Pb NMR shows that two Pb species exist and their relative concentration changes nearly linearly with addition of the mixed chlorides, indicating that the additives to the TeO2-PbO glass are accommodated by changing the Pb species. The 23Na and 35Cl NMR indicate that Na and Cl are distributed in the single-phase glass phase up to the critical point, and at higher concentrations partition to crystalline phases. Transmission electron microscopy shows that the sample at the critical point contains ~10 nm seed nuclei that increase in size and concentration with exposure to the electron beam.« less

Contrast Gain Control Model Fits Masking Data

NASA Technical Reports Server (NTRS)

Watson, Andrew B.; Solomon, Joshua A.; Null, Cynthia H. (Technical Monitor)

1994-01-01

We studied the fit of a contrast gain control model to data of Foley (JOSA 1994), consisting of thresholds for a Gabor patch masked by gratings of various orientations, or by compounds of two orientations. Our general model includes models of Foley and Teo & Heeger (IEEE 1994). Our specific model used a bank of Gabor filters with octave bandwidths at 8 orientations. Excitatory and inhibitory nonlinearities were power functions with exponents of 2.4 and 2. Inhibitory pooling was broad in orientation, but narrow in spatial frequency and space. Minkowski pooling used an exponent of 4. All of the data for observer KMF were well fit by the model. We have developed a contrast gain control model that fits masking data. Unlike Foley's, our model accepts images as inputs. Unlike Teo & Heeger's, our model did not require multiple channels for different dynamic ranges.

Emission Properties from ZnO Quantum Dots Dispersed in SiO2 Matrix

NASA Astrophysics Data System (ADS)

Panigrahi, Shrabani; Basak, Durga

2011-07-01

Dispersion of ZnO quantum dots in SiO2 matrix has been achieved in two techniques based on StÖber method to form ZnO QDs-SiO2 nanocomposites. Sample A is formed with random dispersion by adding tetraethyl orthosilicate (TEOS) to an ethanolic solution of ZnO nanoparticles and sample B is formed with a chain-like ordered dispersion by adding ZnO nanoparticles to an already hydrolyzed ethanolic TEOS solution. The photoluminescence spectra of the as-grown nanocomposites show strong emission in the ultraviolet region. When annealed at higher temperature, depending on the sample type, these show strong red or white emission. Interestingly, when the excitation is removed, the orderly dispersed ZnO QDs-SiO2 composite shows a very bright blue fluorescence visible by naked eyes for few seconds indicating their promise for display applications.

Methyl-modified silica nanobowl for 2D self-organized nanostructure with hydrophobic performance.

PubMed

Chen, Lingling; Sun, Aihua; Wang, Biao; Xu, Gaojie

2018-07-20

A facial method of fabricating methyl-modified silica nanobowl using a polystyrene template with tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) as co-precursors was reported. The morphology of the nanobowl was determined by the mole ratio of TEOS and MTES, and the size and shell thickness of the PS@SiO 2 . And the 2D ordered nanostructure has also been developed with a nanobowl opening perpendicular to the glass substrate surface by the Langmuir-Blodgett technique. These 2D ordered nanobowl structures present an adjustable antireflection property. The single-side nanobowl coating has a transmission improvement of 4.5% compared to the uncoated glass at a wavelength of 540 nm. Furthermore, the nanobowl structures have good hydrophobicity with a contact angle up to 130° without any additional treatment. The quantitative deformation behavior of the methyl-modified silica nanobowl was also discussed.

Luminescent properties of Ln3+ doped tellurite glasses containing AlF3

NASA Astrophysics Data System (ADS)

Walas, Michalina; Pastwa, Agata; Lewandowski, Tomasz; Synak, Anna; Gryczyński, Ignacy; Sadowski, Wojciech; Kościelska, Barbara

2016-09-01

The low-phonon energy tellurite glasses TeO2-BaO-Bi2O3 and TeO2-BaO-Bi2O3-AlF3 triply doped with Eu3+, Tb3+, Tm3+ ions in two different molar ratios were synthesized using melt-quenching technique. Their structure and luminescence properties were widely investigated by X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and Photoluminescence Spectroscopy (PL). The luminescence spectra of Eu3+, Tb3+, Tm3+ co-doped glasses show apart of the bands corresponding to the 4f-4f transitions of lanthanide ions also band corresponding to glass matrix. AlF3 doping increases emission intensity, although to improve overall emission color further studies on molar composition of samples and the molar ratio of the components should be carried out.

Fabrication and characterization of an all-solid tellurite-phosphate photonic bandgap fiber.

PubMed

Cheng, Tonglei; Sakai, Yukiko; Suzuki, Takenobu; Ohishi, Yasutake

2015-05-01

We present an all-solid tellurite-phosphate photonic bandgap fiber (PBGF) with two layers of high-index rods (TeO2-Li2O-WO3-MoO3-Nb2O5, TLWMN) in the cladding (TeO2-ZnO-Li2O-K2O-Al2O3-P2O5, TZLKAP). TLWMN and TZLKAP glasses have good compatibility for fabricating the all-solid PBGF. Photonic bandgap (PBG) properties are calculated by the plane wave expansion method (PWM), and the results agree well with the measured transmission spectrum. Furthermore, the modal field patterns are measured at ∼1300 and 1520 nm, respectively. The light is confined to the core at ∼1300  nm and lost in the cladding at ∼1520  nm, which match well with the calculated modal field intensities.

Rheological properties of poly(vinyl alcohol) (PVA) derived composite membranes for fuel cells

NASA Astrophysics Data System (ADS)

Remiš, T.

2017-01-01

Rheological properties of new anhydrous proton conducting membrane based on PVA, tetraethyl orthosilicate (TEOS),sulfosuccinic acid (SSA), titanium dioxide (TiO2)was examined at various stoichiometric ratios. SSA was used as sulfonating agents to form a crosslinked structure and as proton source, whereas TEO Sand TiO2were utilized to improve the thermal and mechanical properties of the membrane. In order to verify that all the substances were immobilized into the matrix, the membranes were analysed by means of FT-IR. The rheological, mechanical and thermal properties of the membranes were investigated using rheometer ARES G2 and thermogravimetic analyser (TGA).The analysis of mixed PVA solutions exhibited a unique behaviour of viscosity with increased crosslink density. The dynamic storage modulus G´ of dried composite membranes shows better mechanical resistance and increased tolerance to pressure applied during membrane electrode assembly (MEA).

A Summary/Overview of Ejector Augmentor Theory and Performance. Volume 1. Technical Discussion

DTIC Science & Technology

1979-09-01

P Tt ’ Pt m m P - tp pp ptm Pt P Pt Tt n CONSTANT PRESSURE MIXIN -,"--"MIXING INITIAL HEAT ADDITION TO THE PRIMARY w It s sm S Sm ENTROPY, s FfGURE 2...TEMPERATURE-ENTROPY DIAGRAM FOR AN EJECTOR CYCLE ........ . .. I.... ...T H NITIAL HEAT ADDITION TO THE PRIMARY s s sm s8 psi Pt s Tt s ex AIR Uu...s Sm = (8) This Increase in entropy drives the cycle performance to lower values of calcu- lated p, as shown in Figure 4. The only boundary condition

Gas-Phase Synthesis of Gold- and Silica-Coated Nanoparticles

NASA Astrophysics Data System (ADS)

Boies, Adam Meyer

2011-12-01

Composite nanoparticles consisting of separate core-shell materials are of interest for a variety of biomedical and industrial applications. By combining different materials at the nanoscale, particles can exhibit enhanced or multi-functional behavior such as plasmon resonance combined with superparamagnetism. Gas-phase nanoparticle synthesis processes are promising because they can continuously produce particles with high mass-yield rates. In this dissertation, new methods are investigated for producing gas-phase coatings of nanoparticles in an "assembly-line" fashion. Separate processes are developed to create coatings from silica and gold that can be used with a variety of core-particle chemistries. A photoinduced chemical vapor deposition (photo-CVD) method is used to produce silica coatings from tetraethyl orthosilicate (TEOS) on the surface of nanoparticles (diameter ˜5--70 nm). Tandem differential mobility analysis (TDMA) of the process demonstrates that particle coatings can be produced with controllable thicknesses (˜1--10 nm) by varying system parameters such as precursor flow rate. Electron microscopy and infrared spectroscopy confirm that the photo-CVD films uniformly coat the particles and that the coatings are silica. In order to describe the coating process a chemical mechanism is proposed that includes gas-phase, surface and photochemical reactions. A chemical kinetics model of the mechanism indicates that photo-CVD coating proceeds primarily through the photodecomposition of TEOS which removes ethyl groups, thus creating activated TEOS species. The activated TEOS then adsorbs onto the surface of the particle where a series of subsequent reactions remove the remaining ethyl groups to produce a silica film with an open site for further attachment. The model results show good agreement with the experimentally measured coating trends, where increased TEOS flow increases coating thickness and increased nitrogen flow decreases coating thickness. Gold

Derivatives of a Vancomycin-Resistant Staphylococcus aureus Strain Isolated at Hershey Medical Center

PubMed Central

Bozdogan, Bülent; Ednie, Lois; Credito, Kim; Kosowska, Klaudia; Appelbaum, Peter C.

2004-01-01

Antimicrobial susceptibilities and genetic relatedness of the vancomycin-resistant Staphylococcus aureus strain (VRSA) isolated at Hershey, Pa. (VRSA Hershey), and its vancomycin-susceptible and high-level-resistant derivatives were studied and compared to 32 methicillin-resistant S. aureus strains (MRSA) isolated from patients and medical staff in contact with the VRSA patient. Derivatives of VRSA were obtained by subculturing six VRSA colonies from the original culture with or without vancomycin. Ten days of drug-free subculture caused the loss of vanA in two vancomycin-susceptible derivatives for which vancomycin MICs were 1 to 4 μg/ml. Multistep selection of three VRSA clones with vancomycin for 10 days increased vancomycin MICs from 32 to 1,024 to 2,048 μg/ml. MICs of teicoplanin, dalbavancin, and oritavancin were also increased from 4, 0.5, and 0.12 to 64, 1, and 32 μg/ml, respectively. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing analysis indicated that VRSA Hershey was the vanA-acquired variety of a common MRSA clone in our hospital with sequence type 5 (ST5). Three of five vancomycin-intermediate S. aureus strains tested from geographically different areas were also ST5, and the Michigan VRSA was ST371, a one-allele variant of ST5. Derivatives of VRSA Hershey had differences in PFGE profiles and the size of SmaI fragment that carries the vanA gene cluster, indicating instability of this cluster in VRSA Hershey. However induction with vancomycin increased glycopeptide MICs and stabilized the resistance. PMID:15561854

Derivatives of a vancomycin-resistant Staphylococcus aureus strain isolated at Hershey Medical Center.

PubMed

Bozdogan, Bülent; Ednie, Lois; Credito, Kim; Kosowska, Klaudia; Appelbaum, Peter C

2004-12-01

Antimicrobial susceptibilities and genetic relatedness of the vancomycin-resistant Staphylococcus aureus strain (VRSA) isolated at Hershey, Pa. (VRSA Hershey), and its vancomycin-susceptible and high-level-resistant derivatives were studied and compared to 32 methicillin-resistant S. aureus strains (MRSA) isolated from patients and medical staff in contact with the VRSA patient. Derivatives of VRSA were obtained by subculturing six VRSA colonies from the original culture with or without vancomycin. Ten days of drug-free subculture caused the loss of vanA in two vancomycin-susceptible derivatives for which vancomycin MICs were 1 to 4 microg/ml. Multistep selection of three VRSA clones with vancomycin for 10 days increased vancomycin MICs from 32 to 1,024 to 2,048 microg/ml. MICs of teicoplanin, dalbavancin, and oritavancin were also increased from 4, 0.5, and 0.12 to 64, 1, and 32 microg/ml, respectively. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing analysis indicated that VRSA Hershey was the vanA-acquired variety of a common MRSA clone in our hospital with sequence type 5 (ST5). Three of five vancomycin-intermediate S. aureus strains tested from geographically different areas were also ST5, and the Michigan VRSA was ST371, a one-allele variant of ST5. Derivatives of VRSA Hershey had differences in PFGE profiles and the size of SmaI fragment that carries the vanA gene cluster, indicating instability of this cluster in VRSA Hershey. However induction with vancomycin increased glycopeptide MICs and stabilized the resistance.

Rapid Identification of Vancomycin Resistant Enterococcus Faecalis Clinical Isolates using a Sugar Fermentation Method

PubMed Central

Raeisi, Javad; Saifi, Mahnaz; Pourshafie, Mohammad Reza; Habibi, Mehri; Mohajerani, Hamid Reza; Akbari, Neda

2017-01-01

Introduction Vancomycin Resistant Enterococci (VRE) can be found all over the world. Thus, rapid detection of the isolates could be of high importance in the treatment or prevention of the associated disease. Aim To measure the turanose fermentation in Enterococcus faecalis clinical isolates for rapid differentiation of VRE and Vancomycin-Susceptible E. faecalis (VSE) isolates. Materials and Methods Forty E. faecalis samples were isolated from 200 clinical samples in Tehran Medical Center, Iran, from October 2012 to December 2012. These isolates were detected according to the standard microbial and biochemical tests. Detection of VRE isolates was originally performed by disk diffusion using 1 μg vancomycin disk, followed by Polymerase Chain Reaction (PCR) amplification of the vanA gene. Finally, the turanose consumption in 1%, 0.7% and 0.5% dilutions was detected by a phenotypic method. Results Among the 40 E. faecalis isolates, 20 vancomycin-susceptible and 20 vancomycin-resistant E. faecalis were isolated according to the disk diffusion and PCR of the vanA gene. There was a considerable difference between VRE and VSE isolates in 0.7% dilution of turanose. However, there was no significant difference between VRE and VSE in 1% and 0.5% dilutions of turanose. Conclusion Since detection of VRE isolates is of high importance, especially in nosocomial infections, phenotypic methods may be highly useful for this purpose. In conclusion, our data indicate that VRE isolated from clinical samples could be distinguished from VSE isolates by turanose fermentation at dilution 0.7%. PMID:28511382

Prevalence of Diverse Clones of Vancomycin-Resistant Enterococcus faecium ST78 in a Chinese Hospital.

PubMed

Yang, Jiyong; Jiang, Yufeng; Guo, Ling; Ye, LIyan; Ma, Yanning; Luo, Yanping

2016-06-01

Vancomycin-resistant Enterococcus (VRE) has been identified in China. However, little is known about the spread of VRE isolates. The genetic relatedness of vancomycin-resistant Enterococcus faecium (VREfm) isolates was analyzed by pulsed-field gel electrophoresis (PFGE), their antimicrobial susceptibilities were analyzed by E-test and the VITEK 2 AST-GP67 test Kit, and their sequence types (STs) were investigated by multilocus sequence typing (MLST). S1-PFGE was used for plasmid profiling, and PCR and subsequent sequencing were performed to identify the virulence genes. A total of 96 nonduplicated VREfm isolates were obtained and categorized into 38 PFGE types (type 1-38). The predominant MLST type was ST78, while ST17, ST341, and ST342 were also sporadically identified. All types of clinical VREfm strains harbored the vanA gene; however, they carried plasmids of different sizes. While 92.1%, 71.1%, and 60.5% of VREfm strains carried hyl, scm, and ecbA genes, respectively, all of them were positive for esp, acm, sgrA, pilA, and pilB genes. Clonal VREfm spread was observed, and nonplasmid-mediated horizontal transfer of vancomycin-resistant gene might have conveyed resistance to some vancomycin-susceptible E. faecium strains. E. faecium ST78 carrying vanA gene was the most prevalent clone in this study. The high prevalence of virulence genes, including esp, hyl, acm, scm, ecbA, sgrA, pilA, and pilB, confirmed their important roles in the emergence of VREfm ST78 in nosocomial infections.

Multidrug-resistant enterococci in animal meat and faeces and co-transfer of resistance from an Enterococcus durans to a human Enterococcus faecium.

PubMed

Vignaroli, Carla; Zandri, Giada; Aquilanti, Lucia; Pasquaroli, Sonia; Biavasco, Francesca

2011-05-01

Forty-eight isolates resistant to at least two antibiotics were selected from 53 antibiotic-resistant enterococci from chicken and pig meat and faeces and analysed for specific resistance determinants. Of the 48 multidrug-resistant (MDR) strains, 31 were resistant to two antibiotics (29 to erythromycin and tetracycline, 1 to erythromycin and vancomycin, 1 to vancomycin and tetracycline), 14 to three (erythromycin, tetracycline and vancomycin or ampicillin) and 3 to four (erythromycin, vancomycin, ampicillin and gentamicin). erm(B), tet(M), vanA and aac (6')-Ie aph (2'')-Ia were the antibiotic resistance genes most frequently detected. All 48 MDR enterococci were susceptible to linezolid and daptomycin. Enterococcus faecalis (16), Enterococcus faecium (8), Enterococcus mundtii (2) and Enterococcus gallinarum (1) were identified in meat, and E. faecium (13) and Enterococcus durans (13) in faeces. Clonal spread was not detected, suggesting a large role of gene transfer in the dissemination of antibiotic resistance. Conjugative transfer of resistance genes was more successful when donors were enterococcal strains isolated from faeces; co-transfer of vanA and erm(B) to a human E. faecium occurred from both E. faecium and E. durans pig faecal strains. These data show that multidrug resistance can be found in food and animal species other than E. faecium and E. faecalis, and that these species can efficiently transfer antibiotic resistance to human strains in inter-specific matings. In particular, the occurrence of MDR E. durans in the animal reservoir could have a role in the emergence of human enterococcal infections difficult to eradicate with antibiotics.

Molecular epidemiology of vancomycin resistant enterococci in a tertiary care hospital in Saudi Arabia.

PubMed

Somily, Ali M; Al-Mohizea, Maha M; Absar, Muhammed M; Fatani, Amal J; Ridha, Afaaf M; Al-Ahdal, Mohammed N; Senok, Abiola C; Al-Qahtani, Ahmed A

2016-08-01

Vancomycin-resistant enterococci (VRE) are a major cause of nosocomial infections with high mortality and morbidity. There is limited data on the molecular characterization of VRE in Saudi Arabia. This study was carried out to investigate the premise that a shift in VRE epidemiology is occurring in our setting. Enterococcus species identification and susceptibility testing plus VRE phenotypic confirmation by vancomycin and teicoplanin E-test were carried out. Vancomycin resistance genes were detected by PCR. Strain typing was conducted using PFGE. Among the strains of Enterococcus spp. investigated in this study, 17 (4.5%) were VRE. With the exception of one isolate from rectal swab, all others were clinical specimens with blood being the commonest source (n = 11; 64.7%), followed by urine (n = 3; 17.6%). The 17 VRE isolates were Enterococcus faecium (n/N = 13/17) and Enterococcus gallinarum (n/N = 4/17). Among E. faecium isolates, vanA(+)/vanB(+) (n/N = 8/13; 62%) exhibiting VanB phenotype were predominant. One of the five vanA(+)E. faecium isolates exhibited a VanB phenotype indicative of vanA genotype-VanB phenotype incongruence. E. gallinarum isolates exhibited a Van C phenotype although two were vanA(+)/vanC1(+). PFGE revealed a polyclonal distribution with eight pulsotypes. These findings indicate an evolving VRE epidemiology with vanA(+)/vanB(+) isolates and vanA genotype-VanB phenotype incongruence isolates, which were previously described as colonizers, are now causing clinical infection. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation of bio-compatible boron nanoparticles and novel mesoporous silica nanoparticles for bio-applications

NASA Astrophysics Data System (ADS)

Gao, Zhe

This dissertation presents the synthesis and characterization of several novel inorganic and hybrid nanoparticles, including the bio-compatible boron nanoparticles (BNPs) for boron neutron capture therapy (BNCT), tannic acid-templated mesoporous silica nanoparticles and degradable bridged silsesquioxane silica nanoparticles. Chapter 1 provides background information of BNCT and reviews the development of design and synthesizing silica nanoparticles and the study of silica material degradability. Chapter 2 describes the preparation and characterization of dopamine modified BNPs and the preliminary cell study of them. The BNPs were first produced via ball milling, with fatty acid on the surface to stabilize the combustible boron elements. This chapter will mainly focus on the ligand-exchange strategy, in which the fatty acids were replaced by non-toxic dopamines in a facile one-pot reaction. The dopamine-coated BNPs (DA-BNPs) revealed good water dispersibility and low cytotoxicity. Chapter 3 describes the synthesis of tannic acid template mesoporous silica nanoparticles (TA-TEOS SiNPs) and their application to immobilize proteins. The monodispersed TA SiNPs with uniform pore size up to approximately 13 nm were produced by utilizing tannic acid as a molecular template. We studied the influence of TA concentration and reaction time on the morphology and pore size of the particles. Furthermore, the TA-TEOS particles could subsequently be modified with amine groups allowing them to be capable of incorporating imaging ligands and other guest molecules. The ability of the TA-TEOS particles to store biomolecules was preliminarily assessed with three proteins of different charge characteristics and dimensions. The immobilization of malic dehydrogenase on TA-TEOS enhanced the stability of the enzyme at room temperature. Chapter 4 details the synthesis of several bridged silsesquioxanes and the preparation of degradable hybrid SiNPs via co-condensation of bridged

Assistant template and co-template agents in modeling mesoporous silicas and post-synthesizing organofunctionalizations

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

Oliveira, Vaeudo V.; Airoldi, Claudio, E-mail: airoldi@iqm.unicamp.br

2012-12-15

Mesoporous SBA-16 silicas were synthesized through a direct methodology using the template (F127) combined with co-templates (ethanol and n-butanol), with tetraethylorthosilicate as the silica source. These ordered mesoporous silica were characterized by elemental analyses, infrared spectroscopy, solid-state nuclear magnetic resonance for {sup 13}C (CP/MAS) and {sup 29}Si (HP/DEC) nuclei, nitrogen sorption/desorption processes, small angle X-ray analyses (SAXS) and transmission electron microscopy (TEM). SAXS and TEM results confirmed the space group Im3m and cubic 3D symmetry, typical for highly ordered SBA-16. The sorption/desorption data for SBA-16 and when functionalized gave type IV isotherms, with hysteresis loop H2. Surface areas of 836;more » 657 and 618 m{sup 2} g{sup -1} and average pore diameters of 7.99; 8.10 and 9.85 nm, for SBA-16A, SBA-16B and SBA-16C were obtained, respectively. When functionalized the silicas presented a reduction in surface area, pore volume and pore diameter due to the pendant chains that interfere with nitrogen sorption in these measurements. The co-template ethanol favors the ordered mesopores with highest wall thicknesses. - Graphical Abstract: The mesoporous SBA-16 can be synthesized from binary (F127/TEOS) or ternary (F127/alcohol/TEOs) systems to give well-ordered mesoporous silicas. The co-templates ethanol or butanol gave the final material with highest wall thickness, mainly with ethanol. After these syntheses the pores were successfully organofunctionalized to give a good incorporation of the silylating agents. The final silicas presented of well-arranged solid characteristics as expressing by three distinct peaks, as indexed by the corresponding planes. Highlights: Black-Right-Pointing-Pointer Syntheses of mesoporous silicas by using ternary (F127/agent/TEOS) and binary (F127/TEOS) systems. Black-Right-Pointing-Pointer Use of co-templates to synthesize mesoporous silicas with larger wall thicknesses. Black

A 125Te and 23Na NMR investigation of the structure and crystallisation of sodium tellurite glasses.

PubMed

Holland, D; Bailey, J; Ward, G; Turner, B; Tierney, P; Dupree, R

2005-01-01

125Te static nuclear magnetic resonance (NMR) and 23Na and 125Te magic angle spinning (MAS) NMR have been used, in conjunction with X-ray diffraction, to examine the structure and crystallisation behaviour of glasses of composition xNa2O.(1-x)TeO2 (0.075 x 0.4). The MAS NMR 23Na spectra from the glasses are broad and featureless but shift by approximately +5 ppm with increased x, i.e. as the system becomes more ionic. The static 125Te NMR spectra show an increase in axial symmetry with increasing x, indicating a shift from predominantly [TeO4] to [TeO3] structural units. The 23Na and 125Te spectra from the crystallised samples have been fitted to obtain information on the sites in the metastable crystal phases, which are the first to form on heating and which are therefore more closely related to the glass structure than thermodynamically stable crystal phases. New sodium tellurite phases are reported, including a sodium stabilised, face centred cubic phase related to delta-TeO2; a metastable form of Na2Te4O9 containing 3 sodium and 4 tellurium sites; and a metastable form of Na2Te2O5 containing 2 sodium sites. There is evidence of oxidation of TeIV to TeVI occurring in glasses with high values of x and, at x=0.40 and 0.50 (outside the glass forming range), some sodium metatellurate (Na2TeO4) is formed at the same time as sodium metatellurite (Na2TeO3). The 125Te shift is very sensitive to environment within the sodium tellurite system, covering more than 320 ppm, with anisotropies varying from 640 to 1540 ppm. The lack of features in the 125Te spectra of the glass phases, combined with the large shift range and high but variable anisotropy, means than it is not possible to obtain a unique fit to any presumed species present. Furthermore, the chemical shift anisotropy parameters for three of the four Te sites in the Na2Te4O9 phase are found to lie outside the range used for previous simulations of glass spectra.

Prototyping Of Patterned Functional Nanostructures

DOEpatents

Fan, Hongyou; Lopez, Gabriel P.; Brinker, Charles Jeffrey; Lu, Yunfeng

2002-10-29

The present invention provides a coating composition comprising: A coating composition comprising: TEOS; a surfactant; at least one organosilane; HCl; water; and ethanol. The present invention also provides films made from such a coating composition and a method for making such films.

Computational modeling of the neural representation of object shape in the primate ventral visual system

PubMed Central

Eguchi, Akihiro; Mender, Bedeho M. W.; Evans, Benjamin D.; Humphreys, Glyn W.; Stringer, Simon M.

2015-01-01

Neurons in successive stages of the primate ventral visual pathway encode the spatial structure of visual objects. In this paper, we investigate through computer simulation how these cell firing properties may develop through unsupervised visually-guided learning. Individual neurons in the model are shown to exploit statistical regularity and temporal continuity of the visual inputs during training to learn firing properties that are similar to neurons in V4 and TEO. Neurons in V4 encode the conformation of boundary contour elements at a particular position within an object regardless of the location of the object on the retina, while neurons in TEO integrate information from multiple boundary contour elements. This representation goes beyond mere object recognition, in which neurons simply respond to the presence of a whole object, but provides an essential foundation from which the brain is subsequently able to recognize the whole object. PMID:26300766

Sol-gel hybrid films based on organosilane and montmorillonite for corrosion inhibition of AA2024.

PubMed

Dalmoro, V; dos Santos, J H Z; Armelin, E; Alemán, C; Azambuja, D S

2014-07-15

The present work reports the production of films on AA2024-T3 composed of vinyltrimethoxysilane (VTMS)/tetraethylorthosilicate (TEOS) with incorporation of montmorillonite (sodium montmorillonite and montmorillonite modified with quaternary ammonium salt, abbreviated Na and 30B, respectively), generated by the sol-gel process. According to FT-IR analyses the incorporation of montmorillonite does not affect silica network. Electrochemical characterization was performed by electrochemical impedance spectroscopy measurement in 0.05 mol L(-1) NaCl solution. Results indicate that montmorillonite incorporation improves the corrosion protection compared to the non-modified system. Scanning electron microscopy micrographs reveal that high concentrations of montmorillonite provide agglomerations on the metallic surface, which is in detriment of the anticorrosive performance. The VTMS/TEOS/30B films with the lowest concentration (22 mg L(-1)) of embedded clay provide the highest corrosion protection. Copyright © 2014 Elsevier Inc. All rights reserved.

Composites in small and simple devices to increase mixing on detector surfaces

NASA Astrophysics Data System (ADS)

Hernandez, L. F.; Lima, R. R.; Leite, A. R.; Fachini, E. R.; Silva, M. L. P.

2013-03-01

This work aims at three different applications for the betterment of plasma generated-composite thin films: pre-mixing, spray formation in miniaturized structures and an increase in the performance of detector surfaces. Miniaturized structures were projected, simulated with FEMLAB® 3.2 software and then constructed. Clustered films made from tetraethoxysilane (TEOS) and nonafluoro(iso)butyl ether (HFE®) precursors were deposited on silicon, acrylic and quartz substrates for different kinds of film characterization/or in the projected structures. Physical and chemical characterization guided the selection of best films previous to/after UVC exposure. The active surfaces (plasma-deposited films) in structures were modified by UVC exposure and then tested. The applications include pre-mixing of liquids and/or spray formation, best results being obtained with surface covered by derivative-HFE films, which acted as passivation layers. Preliminary results show good humidity sensing for TEOS-derivative films.

Deactivation of photocatalytically active ZnO nanoparticle and enhancement of its compatibility with organic compounds by surface-capping with organically modified silica

NASA Astrophysics Data System (ADS)

Cao, Zhi; Zhang, Zhijun

2011-02-01

Tetraethyl orthosilicate (TEOS) and dimethyldiethoxysilane (DEDMS) were used as co-precursors to prepare organically modified silica (ormosil) via sol-gel process. The resultant ormosil was adopted for surface-capping of ZnO nanoparticle, where methyl (organic functional group) and silica (inorganic component) were simultaneously introduced onto the surface of the nanoparticles for realizing dual surface-modification. The ormosil-capped ZnO nanoparticle showed strong hydrophobicity and good compatibility with organic phases, as well as effectively decreased photocatalytic activity and almost unchanged ultraviolet (UV)-shielding ability. More importantly, the comprehensive properties of ormosil-capped ZnO nanoparticle could be manipulated by adjusting the molar ratio of TEOS to DEDMS during sol-gel process. This should help to open a wider window to better utilizing the unique and highly attractive properties such as high UV-shielding ability and high-visible light transparency of ZnO nanoparticle in sunscreen cosmetics.

Proteomic characterization of vanA-containing Enterococcus recovered from Seagulls at the Berlengas Natural Reserve, W Portugal.

PubMed

Radhouani, Hajer; Poeta, Patrícia; Pinto, Luís; Miranda, Júlio; Coelho, Céline; Carvalho, Carlos; Rodrigues, Jorge; López, María; Torres, Carmen; Vitorino, Rui; Domingues, Pedro; Igrejas, Gilberto

2010-09-21

Enterococci have emerged as the third most common cause of nosocomial infections, requiring bactericidal antimicrobial therapy. Although vancomycin resistance is a major problem in clinics and has emerged in an important extend in farm animals, few studies have examined it in wild animals. To determine the prevalence of vanA-containing Enterococcus strains among faecal samples of Seagulls (Larus cachinnans) of Berlengas Natural Reserve of Portugal, we developed a proteomic approach integrated with genomic data. The purpose was to detect the maximum number of proteins that vary in different enterococci species which are thought to be connected in some, as yet unknown, way to antibiotic resistance. From the 57 seagull samples, 54 faecal samples showed the presence of Enterococcus isolates (94.7%). For the enterococci, E. faecium was the most prevalent species in seagulls (50%), followed by E. faecalis and E. durans (10.4%), and E. hirae (6.3%). VanA-containing enterococcal strains were detected in 10.5% of the 57 seagull faecal samples studied. Four of the vanA-containing enterococci were identified as E. faecium and two as E. durans. The tet(M) gene was found in all five tetracycline-resistant vanA strains. The erm(B) gene was demonstrated in all six erythromycin-resistant vanA strains. The hyl virulence gene was detected in all four vanA-containing E. faecium isolates in this study, and two of them harboured the purK1 allele. In addition these strains also showed ampicillin and ciprofoxacin resistance. The whole-cell proteomic profile of vanA-containing Enterococcus strains was applied to evaluate the discriminatory power of this technique for their identification. The major differences among species-specific profiles were found in the positions corresponding to 97-45 kDa. Sixty individualized protein spots for each vanA isolate was identified and suitable for peptide mass fingerprinting measures by spectrometry measuring (MALDI/TOF MS) and their identification

Proteomic characterization of vanA-containing Enterococcus recovered from Seagulls at the Berlengas Natural Reserve, W Portugal

PubMed Central

2010-01-01

Background Enterococci have emerged as the third most common cause of nosocomial infections, requiring bactericidal antimicrobial therapy. Although vancomycin resistance is a major problem in clinics and has emerged in an important extend in farm animals, few studies have examined it in wild animals. To determine the prevalence of vanA-containing Enterococcus strains among faecal samples of Seagulls (Larus cachinnans) of Berlengas Natural Reserve of Portugal, we developed a proteomic approach integrated with genomic data. The purpose was to detect the maximum number of proteins that vary in different enterococci species which are thought to be connected in some, as yet unknown, way to antibiotic resistance. Results From the 57 seagull samples, 54 faecal samples showed the presence of Enterococcus isolates (94.7%). For the enterococci, E. faecium was the most prevalent species in seagulls (50%), followed by E. faecalis and E. durans (10.4%), and E. hirae (6.3%). VanA-containing enterococcal strains were detected in 10.5% of the 57 seagull faecal samples studied. Four of the vanA-containing enterococci were identified as E. faecium and two as E. durans. The tet(M) gene was found in all five tetracycline-resistant vanA strains. The erm(B) gene was demonstrated in all six erythromycin-resistant vanA strains. The hyl virulence gene was detected in all four vanA-containing E. faecium isolates in this study, and two of them harboured the purK1 allele. In addition these strains also showed ampicillin and ciprofoxacin resistance. The whole-cell proteomic profile of vanA-containing Enterococcus strains was applied to evaluate the discriminatory power of this technique for their identification. The major differences among species-specific profiles were found in the positions corresponding to 97-45 kDa. Sixty individualized protein spots for each vanA isolate was identified and suitable for peptide mass fingerprinting measures by spectrometry measuring (MALDI/TOF MS) and their

A theta rhythm in macaque visual cortex and its attentional modulation

PubMed Central

Spyropoulos, Georgios; Fries, Pascal

2018-01-01

Theta rhythms govern rodent sniffing and whisking, and human language processing. Human psychophysics suggests a role for theta also in visual attention. However, little is known about theta in visual areas and its attentional modulation. We used electrocorticography (ECoG) to record local field potentials (LFPs) simultaneously from areas V1, V2, V4, and TEO of two macaque monkeys performing a selective visual attention task. We found a ≈4-Hz theta rhythm within both the V1–V2 and the V4–TEO region, and theta synchronization between them, with a predominantly feedforward directed influence. ECoG coverage of large parts of these regions revealed a surprising spatial correspondence between theta and visually induced gamma. Furthermore, gamma power was modulated with theta phase. Selective attention to the respective visual stimulus strongly reduced these theta-rhythmic processes, leading to an unusually strong attention effect for V1. Microsaccades (MSs) were partly locked to theta. However, neuronal theta rhythms tended to be even more pronounced for epochs devoid of MSs. Thus, we find an MS-independent theta rhythm specific to visually driven parts of V1–V2, which rhythmically modulates local gamma and entrains V4–TEO, and which is strongly reduced by attention. We propose that the less theta-rhythmic and thereby more continuous processing of the attended stimulus serves the exploitation of this behaviorally most relevant information. The theta-rhythmic and thereby intermittent processing of the unattended stimulus likely reflects the ecologically important exploration of less relevant sources of information. PMID:29848632

Structural and luminescence studies on Dy3+ doped lead boro-telluro-phosphate glasses

NASA Astrophysics Data System (ADS)

Selvi, S.; Venkataiah, G.; Arunkumar, S.; Muralidharan, G.; Marimuthu, K.

2014-12-01

This paper reports results obtained on the structural and luminescence properties of Dy3+doped lead boro-telluro-phosphate glasses prepared following the melt quenching technique. FTIR spectra exhibit the presence of B-O vibrations, P-O-P symmetric vibrations and Te-O stretching modes of TeO3 and TeO6 units. The metal-ligand bond was identified through UV-vis-NIR absorption spectra and to determine the band tailing parameter, direct and indirect band gap energy of the prepared glasses. The Judd-Ofelt (JO) intensity parameters (Ω2, Ω4 and Ω6), experimental and theoretical oscillator strengths were also determined and reported. Luminescence measurements were made to determine the transition probability (A), stimulated emission cross-section (σPE) and branching ratio (βR) for the transitions that include 4F9/2→6H11/2, 6H13/2 and 6H15/2 bands. The effect of Dy3+ ion concentration on the intensity ratio of yellow to blue emission bands has also been studied and reported. The lifetime corresponding to the 4F9/2 level of the title glasses has been found to decrease with the increase in Dy3+ ion concentration. The chromaticity coordinates (x,y) have been estimated from the luminescence spectra and the suitability of title glasses for white light applications has been analyzed using CIE chromaticity diagram. The variation of optical properties with the concentration of dysprosium oxide content in the glasses have been studied and reported.

Highly Luminescent Hybrid SiO2-Coated CdTe Quantum Dots Retained Initial Photoluminescence Efficiency in Sol-Gel SiO2 Film.

PubMed

Sun, Hongsheng; Xing, Yugui; Wu, Qinan; Yang, Ping

2015-02-01

A highly luminescent silica film was fabricated using tetraethyl orthosilicate (TEOS) and 3-aminopropyltrimethoxysilane (APS) through a controlled sol-gel reaction. The pre-hydrolysis of TEOS and APS which resulted in the mixture of TEOS and APS in a molecular level is a key for the formation of homogenous films. The aminopropyl groups in APS play an important role for obtaining homogeneous film with high photoluminescence (PL). Red-emitting hybrid SiO2-coated CdTe nano-crystals (NCs) were fabricated by a two-step synthesis including a thin SiO2 coating via a sol-gel process and a subsequent refluxing using green-emitting CdTe NCs. The hybrid SiO2-coated CdTe NCs were embedded in a functional SiO2 film via a two-step process including adding the NCs in SiO2 sol with a high viscosity and almost without ethanol and a subsequent spinning coating. The hybrid SiO2-coated CdTe NCs retained their initial PL efficiency (54%) in the film. Being encapsulated with the hybrid NCs in the film, no change on the absorption and PL spectra of red-emitting CdTe NCs (632 nm) was observed. This indicates the hybrid NCs is stable enough during preparation. This phenomenon is ascribed to the controlled sol-gel process and a hybrid SiO2 shell on CdTe NCs. Because these films exhibited high PL efficiency and stability, they will be utilizable for potential applications in many fields.

Triconstituent co-assembly to ordered mesostructured polymer-silica and carbon-silica nanocomposites and large-pore mesoporous carbons with high surface areas.

PubMed

Liu, Ruili; Shi, Yifeng; Wan, Ying; Meng, Yan; Zhang, Fuqiang; Gu, Dong; Chen, Zhenxia; Tu, Bo; Zhao, Dongyuan

2006-09-06

Highly ordered mesoporous polymer-silica and carbon-silica nanocomposites with interpenetrating networks have been successfully synthesized by the evaporation-induced triconstituent co-assembly method, wherein soluble resol polymer is used as an organic precursor, prehydrolyzed TEOS is used as an inorganic precursor, and triblock copolymer F127 is used as a template. It is proposed for the first time that ordered mesoporous nanocomposites have "reinforced concrete"-structured frameworks. By adjusting the initial mass ratios of TEOS to resol, we determined the obtained nanocomposites possess continuous composition with the ratios ranging from zero to infinity for the two constituents that are "homogeneously" dispersed inside the pore walls. The presence of silicates in nanocomposites dramatically inhibits framework shrinkage during the calcination, resulting in highly ordered large-pore mesoporous carbon-silica nanocomposites. Combustion in air or etching in HF solution can remove carbon or silica from the carbon-silica nanocomposites and yield ordered mesoporous pure silica or carbon frameworks. The process generates plenty of small pores in carbon or/and silica pore walls. Ordered mesoporous carbons can then be obtained with large pore sizes of approximately 6.7 nm, pore volumes of approximately 2.0 cm(3)/g, and high surface areas of approximately 2470 m(2)/g. The pore structures and textures can be controlled by varying the sizes and polymerization degrees of two constituent precursors. Accordingly, by simply tuning the aging time of TEOS, ordered mesoporous carbons with evident bimodal pores at 2.6 and 5.8 nm can be synthesized.

Morcellation worsens survival outcomes in patients with undiagnosed uterine leiomyosarcomas: A retrospective MITO group study.

PubMed

Raspagliesi, Francesco; Maltese, Giuseppa; Bogani, Giorgio; Fucà, Giovanni; Lepori, Stefano; De Iaco, Pierandrea; Perrone, Myriam; Scambia, Giovanni; Cormio, Gennaro; Bogliolo, Stefano; Bergamini, Alice; Bifulco, Giuseppe; Casali, Paolo Giovanni; Lorusso, Domenica

2017-01-01

To investigate the impact of morcellation on survival outcomes of patients affected by undiagnosed uterine sarcoma. This is a retrospective study performed in 8 referral centers of MITO group. Data of women undergoing morcellation for apparent benign uterine myomas who were ultimately diagnosed with stage I uterine sarcoma on final pathology were compared with data of women who did not undergo morcellation. Uterine sarcoma included: leiomyosarcomas (LMS), smooth muscle tumors of uncertain malignant potential (STUMP), low-grade endometrial stromal sarcomas (LG-ESS) and undifferentiated uterine sarcomas (UUS). Two-year survival outcomes were evaluated using Kaplan-Meir and Cox models. Overall 125 patients were identified: 31(24.8%), 21(16.8%) and 73(58.4%) patients had power morcellation during laparoscopy, non power morcellation during open surgery and non morcellation during open procedures, respectively. Considering patients affected by LMS, morcellation did not correlated with disease-free survival. However, patients undergoing either morcellation or power morcellation experienced a 3-fold increase risk of death in comparison to patients who had not morcellation (p=0.02). A trend towards an increase of recurrence was observed for patients undergoing morcellation for STUMP (HR 7.7, p=0.09); while no differences in survival outcomes were observed for patients with LG-ESS and UUS. Our data suggest that morcellation increase the risk of death in patients affected by undiagnosed LMS. Further prospective studies are warranted in order to assess the risk to benefit ratio of power morcellator utilization in patients with apparent benign uterine myomas. Copyright © 2016 Elsevier Inc. All rights reserved.

Instructor Role Conflict in Educational Organizations Having the Characteristics of Total Institutions.

ERIC Educational Resources Information Center

Bamburger, Peter; Hasgall, Alon

1995-01-01

Examines whether findings on teacher role conflict may be generalized to instructors in (Israeli) military academies and training facilities. Aims to identify additional antecedents of instructor role conflict that may have especially powerful effects in total educational organizations (TEOs). Although work design characteristics may influence the…

Non-switching to switching transferring mechanism investigation for Ag/SiO x /p-Si structure with SiO x deposited by HWCVD

NASA Astrophysics Data System (ADS)

Liu, Yanhong; Wang, Ruoying; Li, Zhongyue; Wang, Song; Huang, Yang; Peng, Wei

2018-04-01

We proposed and fabricated an Ag/SiO x /p-Si sandwich structure, in which amorphous SiO x films were deposited through hot wire chemical vapor deposition (HWCVD) using tetraethylorthosilicate (TEOS) as Si and O precursor. Experimental results indicate that the I–V properties of this structure transfer from non-switching to switching operation as the SiO x deposition temperature increased. The device with SiO x deposited at high deposition temperature exhibits typical bipolar switching properties, which can be potentially used in resistive switching random accessible memory (RRAM). The transferring mechanism from non-switching to switching can be ascribed to the change of structural and electronic properties of SiO x active layer deposited at different temperatures, as evidenced by analyzing FTIR spectrum and fitting its I–V characteristics curves. This work demonstrates a safe and practicable low-temperature device-grade SiO x film deposition technology by conducting HWCVD from TEOS.

The synthesis of novel hybrid thiol-functionalized nano-structured SBA-15

NASA Astrophysics Data System (ADS)

Hoang, Van Duc; Phuong Dang, Tuyet; Khieu Dinh, Quang; Phu Nguyen, Huu; Vu, Anh Tuan

2010-09-01

Mesoporous thiol-functionalized SBA-15 has been directly synthesized by co-condensation of tetraethyl orthosilicate (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) with triblock copolymer P123 as-structure-directing agent under hydrothermal conditions. Surfactant removal was performed by Soxhlet ethanol extraction. These materials have been characterized by powder x-ray diffraction (XRD), nitrogen adsorption/desorption (BET model), transmission electron microscopy (TEM), thermal analysis, infrared spectroscopy (IR) and energy-dispersive x-ray spectroscopy (EDX). The main parameters, such as the initial molar ratio of MPTMS to TEOS, the time of adding MPTMS to synthesized gel and the Soxhlet ethanol extraction on the thiol functionalized SBA-15 with high thiol content and highly ordered hexagonal mesostructure, were investigated and evaluated. The adsorption capacity of the thiol-functionalized and non-functionalized SBA-15 materials for Pb2+ ion from aqueous solution was tested. It was found that the Pb2+ adsorption capacity of the thiol functionalized SBA-15 is three times higher than that of non-functionalized SBA-15.

Sol-gel preparation of hydrophobic silica antireflective coatings with low refractive index by base/acid two-step catalysis.

PubMed

Cai, Shuang; Zhang, Yulu; Zhang, Hongli; Yan, Hongwei; Lv, Haibing; Jiang, Bo

2014-07-23

Hydrophobic antireflective coatings with a low refractive index were prepared via a base/acid-catalyzed two-step sol-gel process using tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) as precursors, respectively. The base-catalyzed hydrolysis of TEOS leads to the formation of a sol with spherical silica particles in the first step. In the second step, the acid-catalyzed MTES hydrolysis and condensation occur at the surface of the initial base-catalyzed spherical silica particles, which enlarge the silica particle size from 12.9 to 35.0 nm. By a dip-coating process, this hybrid sol gives an antireflective coating with a refractive index of about 1.15. Moreover, the water contact angles of the resulted coatings increase from 22.4 to 108.7° with the increases of MTES content, which affords the coatings an excellent hydrophobicity. A "core-shell" particle growth mechanism of the hybrid sol was proposed and the relationship between the microstructure of silica sols and the properties of AR coatings was investigated.

Investigation of novel sol-gel hydrophobic surfaces for desorption electrospray ionization-mass spectrometry analysis.

PubMed

Penna, Andrea; Elviri, Lisa; Careri, Maria; Mangia, Alessandro; Predieri, Giovanni

2011-05-01

Sol-gel-based materials were synthesized, characterized and finally tested as solid supports for desorption electrospray ionization-mass spectrometry (DESI-MS) analysis of a mixture of compounds of different polarity. Films with thickness in the 2-4 μm range were obtained by a dip-coating process using tetraethoxysilane (TEOS) and octyltriethoxysilane (OTES) as sol-gel precursors. Three types of surface with different hydrophobic character were obtained by varying the TEOS/OTES ratio in the sol-gel mixture. Each coating was characterized by atomic force microscopy investigations, gaining insight into homogeneity, smoothness and thickness of the obtained films. To study hydrophobicity of each surface, surface free energy measurements were performed. Different DESI-MS responses were observed when different solvent mixture deposition procedures and solvent spray compositions were investigated. Results were finally compared to those obtained by using commercial polytetrafluoroethylene-coated slides. It was found that surface free energy plays an important role in the desorption/ionization process as a function of the polarity of analytes.

A simple and rapid technique for radiochemical separation of iodine radionuclides from irradiated tellurium using an activated charcoal column.

PubMed

Chattopadhyay, Sankha; Saha Das, Sujata

2009-10-01

A simple and inexpensive method for the separation of medically useful no-carrier-added (nca) iodine radionuclides from bulk amounts of irradiated tellurium dioxide (TeO(2)) target was developed. The beta(-) emitting (131)I radionuclide, produced by the decay of (131)Te through the (nat)Te(n, gamma)(131)Te nuclear reaction, was used for standardization of the radiochemical separation procedure. The radiochemical separation was performed by precipitation followed by column (activated charcoal) chromatography. Quantitative post-irradiation recovery of the TeO(2) target material (98-99%), in a form suitable for reuse in future irradiations, was achieved. The overall radiochemical yield for the complete separation of (131)I was 75-85% (n=8). The separated nca (131)I was of high, approximately 99%, radionuclidic and radiochemical purities and did not contain detectable amounts of the target material. This method can be adopted for the radiochemical separation of other different iodine radionuclides produced from tellurium matrices through cyclotron as well as reactor irradiation.

Porous cellulose diacetate-SiO2 composite coating on polyethylene separator for high-performance lithium-ion battery.

PubMed

Chen, Wenju; Shi, Liyi; Wang, Zhuyi; Zhu, Jiefang; Yang, Haijun; Mao, Xufeng; Chi, Mingming; Sun, Lining; Yuan, Shuai

2016-08-20

The developments of high-performance lithium ion battery are eager to the separators with high ionic conductivity and thermal stability. In this work, a new way to adjust the comprehensive properties of inorganic-organic composite separator was investigated. The cellulose diacetate (CDA)-SiO2 composite coating is beneficial for improving the electrolyte wettability and the thermal stability of separators. Interestingly, the pore structure of composite coating can be regulated by the weight ratio of SiO2 precursor tetraethoxysilane (TEOS) in the coating solution. The electronic performance of lithium ion batteries assembled with modified separators are improved compared with the pristine PE separator. When weight ratio of TEOS in the coating solution was 9.4%, the composite separator shows the best comprehensive performance. Compared with the pristine PE separator, its meltdown temperature and the break-elongation at elevated temperature increased. More importantly, the discharge capacity and the capacity retention improved significantly. Copyright © 2016 Elsevier Ltd. All rights reserved.

Linear and nonlinear optical characteristics of Te nanoparticles-doped germanate glasses

NASA Astrophysics Data System (ADS)

Xu, Zhousu; Guo, Qiangbing; Liu, Chang; Ma, Zhijun; Liu, Xiaofeng; Qiu, Jianrong

2016-10-01

Te nanoparticles (NPs)-doped GeO2-MgO-B2O3-Al2O3-TeO2 glasses were prepared by the conventional melt-quenching method. Based on X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscope observation, the coloration of the glass at high TeO2 concentration is ascribed to the precipitation of elemental Te NPs with a size of 5-10 nm in the germanate glass. Optical absorption spectra and nonlinear optical (NLO) properties of the glass samples were analyzed by UV-3600 spectrophotometry and Z-scan technique, respectively. The nonlinear absorption coefficient ( β) and the imaginary part of the third-order NLO susceptibility (Im χ (3)) were estimated to be 1.74 cm/GW and 1.142 × 10-12 esu for laser power of 95 μW, respectively. Due to the excellent NLO properties, the Te NPs-doped germanate glasses may have potential applications for ultrafast optical switch and photonics.

Integrating sol-gel with cold plasmas modified porous polycaprolactone membranes for the drug-release of silver-sulfadiazine and ketoprofen

NASA Astrophysics Data System (ADS)

Mangindaan, Dave; Chen, Chao-Ting; Wang, Meng-Jiy

2012-12-01

A controlled release system composed of surface modified porous polycaprolactone (PCL) membranes combined with a layer of tetraorthosilicate (TEOS)-chitosan sol-gel was reported in this study. PCL is a hydrophobic, semi-crystalline, and biodegradable polymer with a relatively slow degradation rate. The drugs chosen for release experiments were silver-sulfadiazine (AgSD) and ketoprofen which were impregnated in the TEOS-chitosan sol-gel. The surface modification was achieved by O2 plasma and the surfaces were characterized by water contact angle (WCA) measurements, atomic force microscope (AFM), scanning electron microscope and electron spectroscopy for chemical analysis (ESCA). The results showed that the release of AgSD on O2 plasma treated porous PCL membranes was prolonged when compared with the pristine sample. On the contrary, the release rate of ketoprofen revealed no significant difference on pristine and plasma treated PCL membranes. The prepared PCL membranes showed good biocompatibility for the wound dressing biomaterial applications.

Improving the Selection, Classification, and Utilization of Army Enlisted Personnel: Technical Appendix to the Annual Report

DTIC Science & Technology

1983-10-01

03.1 I20 -06 -20 -26 79.0 SfC sic SCaflayepm VS -09 -27 33 -13 -23 -16 .14 3 .ŝ of 2 2? 09 40-40 .09 -17 -28 .00 .10 -it .’ -20 72 073 040.Uu.s jsos...difference between the chi-squares for these *two models (pattern invariance vs . loading invariance) was computed to be 63.83 with 30 degrees of freedom...paragraphs in order to master or pass the objective or to receive a "GO." Typical criterion-referenced scores are number of objectives A" passed, GO vs . NO

Molecular Epidemiology of Vancomycin-Resistant Enterococcus faecalis and Enterococcus faecium Isolated from Clinical Specimens in the Northwest of Iran.

PubMed

Jahansepas, Ali; Ahangarzadeh Rezaee, Mohammad; Hasani, Alka; Sharifi, Yaeghob; Rahnamaye Farzami, Marjan; Dolatyar, Alireza; Aghazadeh, Mohammad

2018-04-30

This study was conducted to investigate the phenotypic and genotypic characteristics of vancomycin-resistant Enterococcus faecalis and Enterococcus faecium. Antibiotic resistance and virulence genes in the aforementioned resistant isolates were studied using the epsilometer (E)-test and polymerase chain reaction (PCR). These isolates were subjected to typing by pulsed-field gel electrophoresis (PFGE). Thirty vancomycin-resistant enterococci (VRE; 18.75%) were isolated from a total of 160 various clinical specimens cultured for any bacterial growth. Of these, 11 (36.7%) isolates were identified as E. faecalis and 19 (63.3%) as E. faecium. Minimum inhibitory concentrations (MICs) of vancomycin, teicoplanin, and three alternative therapeutic options (linezolid, daptomycin, and quinupristin/dalfopristin) were determined using the E-test. Multiplex PCR was done for confirming species, identification of the resistant genotypes, and the detection of the virulence genes. Finally, the clonal relationship of all VRE strains was studied by PFGE. All VRE strains showed vancomycin MIC ≥256 μg/mL, and 27 (90%) isolates carried the vanA gene, whereas none of the isolates carried vanB. The most common resistance antibiotic pattern observed was toward rifampicin (n = 30 [100%]). Among all virulence genes studied, gelE (n = 28 [93.33%]) was found as the most prevalent virulent gene. VRE isolates exhibited 90%, 46.67%, 100%, and 66.67% resistance to teicoplanin, linezolid, quinupristin/dalfopristin, and daptomycin, respectively. Molecular typing demonstrated 16 PFGE types of VRE isolates (A-P). Although vanA was carried by most of the isolates, PFGE displayed small clonal dissemination among VR E. faecium and VR E. faecalis species.

Use Technology

ERIC Educational Resources Information Center

Teo, Timothy

2013-01-01

Technology acceptance is posited to be influenced by a variety of factors, including individual differences, social influences, beliefs, attitudes and situational influences (Agarwal, 2000; Teo, 2009a). A majority of the conceptualisations of technology acceptance have drawn on theories and models from social psychology, notably the theory of…

Exploring E-Learning Acceptance among University Students in Thailand: A National Survey

ERIC Educational Resources Information Center

Teo, Timothy; Ruangrit, Nammon; Khlaisang, Jintavee; Thammetar, Thapanee; Sunphakitjumnong, Kobkul

2014-01-01

This study surveys the e-learning acceptance of university students in Thailand. One thousand nine hundred and eighty-one (1,981) participants completed the E-Learning Acceptance Measure (Teo, 2010) which measures three constructs that predict e-learning acceptance (tutor quality, perceived usefulness, and facilitating conditions). Data analysis…

Tackling the Transition--The English Mathematics Register and Students Learning through the Medium of Irish

ERIC Educational Resources Information Center

Riordain, Maire Ni; O'Donoghue, John

2011-01-01

The explosion of Gaeilge (Irish)-medium primary and secondary schools has played a crucial role in the rebirth of our native language in Ireland. The popularity of attending Gaeilge-medium education is significant, and continues to increase annually ("Gaeilscoileanna Teo" 2008). However, the majority of Gaeilgeoiri (students who learn…

Abstracts of the International Conference (INFOS 83) on Insulating Films on Semiconductors Held at the University of Technology. Eindhoven (The Netherlands) on 11-13 April 1983.

DTIC Science & Technology

1983-04-13

progressed at the same pace. Initially the analogy with conventional well-known ion sensors, such as the glass membrane electrode, led to the...chemical and physical treatments. The standard etching processing using bromine in methanol can deplete cations and produce a surface layer of TeO2 .(l

The Journey as a Transcultural Experience for International Students

ERIC Educational Resources Information Center

Loynes, Chris; Gurholt, Kirsti Pedersen

2017-01-01

An international two-year Erasmus Mundus MA, Transcultural European Outdoor Studies (TEOS), uses the journey as a central metaphorical concept, the "peregrinatio academica", and experiential pedagogy. Students study human nature interactions through the lens of outdoor education and recreation while travelling for a semester at a time in…

A Partnership Training Program in Breast Cancer Research Using Molecular Imaging Techniques

DTIC Science & Technology

2006-07-01

Laurence GG, Teos L, Haddad GE. Effects of ACE- Inhibition on ANG II and IGF-1 signaling during development and regression of eccentric cardiac...2274. [33] Morawski AM, Winter PM, Crowder KC , Caruthers SD, Fuhrhop RW, Scott MJ, Robertson JD, Abendschein DR, Lanza GM, Wickline SA (2004). Targeted

Expression patterns of ion channels and structural proteins in a multimodal cell type of the avian optic tectum.

PubMed

Lischka, Katharina; Ladel, Simone; Luksch, Harald; Weigel, Stefan

2018-02-15

The midbrain is an important subcortical area involved in distinct functions such as multimodal integration, movement initiation, bottom-up, and top-down attention. Our group is particularly interested in cellular computation of multisensory integration. We focus on the visual part of the avian midbrain, the optic tectum (TeO, counterpart to mammalian superior colliculus). This area has a layered structure with the great advantage of distinct input and output regions. In chicken, the TeO is organized in 15 layers where visual input targets the superficial layers while auditory input terminates in deeper layers. One specific cell type, the Shepherd's crook neuron (SCN), extends dendrites in both input regions. The characteristic feature of these neurons is the axon origin at the apical dendrite. The molecular identity of this characteristic region and thus, the site of action potential generation are of particular importance to understand signal flow and cellular computation in this neuron. We present immunohistochemical data of structural proteins (NF200, Ankyrin G, and Myelin) and ion channels (Pan-Na v , Na v 1.6, and K v 3.1b). NF200 is strongly expressed in the axon. Ankyrin G is mainly expressed at the axon initial segment (AIS). Myelination starts after the AIS as well as the distribution of Na v channels on the axon. The subtype Na v 1.6 has a high density in this region. K v 3.1b is restricted to the soma, the primary neurite and the axon branch. The distribution of functional molecules in SCNs provides insight into the information flow and the integration of sensory modalities in the TeO of the avian midbrain. © 2017 Wiley Periodicals, Inc.

Physical, structural and optical characterizations of borate modified bismuth-silicate-tellurite glasses

NASA Astrophysics Data System (ADS)

Berwal, Neelam; Kundu, R. S.; Nanda, Kirti; Punia, R.; Kishore, N.

2015-10-01

Quaternary bismuthate glasses with compositions xB2O3-(80 - x) Bi2O3-15SiO2-5TeO2 have been prepared by melt-quench technique. X-ray diffraction studies were performed to ascertain the amorphous nature of samples. The density, molar volume and crystalline volume decrease with increase in B2O3 content whereas the glass transition temperature shows the reverse trend. The Raman and FTIR spectra of the studied glasses indicate that B2O3 has been found to exist in the form of BO3 trigonal and BO4 tetrahedral structural units and vibrations corresponding to these structural units increase with increase in B2O3 content. SiO2 is present in the form of SiO4 tetrahedral structural units and TeO2 in the form of TeO3 structural units. Bismuth plays the role of network modifier [BiO6 octahedra] as well as network former [BiO3 pyramids] for all the glass compositions. The optical band gap energy has been calculated from the fitting of both Mott and Davis's model and Hydrogenic excitonic model with the experimentally observed absorption spectra. A good fitting of experimental data with HEM indicates the excitonic formation in the studies glass system. The values of optical band gap energy show nonlinear behavior due to the structural changes that take place in the present glass samples. The Urbach energy calculated using Urbach empirical formula for studied glass samples suggest the possibility of reduction in defect concentrations. The metallization criterion of the presently studied samples suggests that the prepared glasses may be potential candidates for nonlinear optical applications.

Structural, thermal and optical absorption features of heavy metal oxides doped tellurite rich glasses

NASA Astrophysics Data System (ADS)

Kaky, Kawa M.; Lakshminarayana, G.; Baki, S. O.; Kityk, I. V.; Taufiq-Yap, Y. H.; Mahdi, M. A.

In order to improve tellurite glass stability to be applicable for optical fiber amplifier applications, glasses with the composition of (70 - x)TeO2. (10)ZnO. (10)WO3. (5)Na2O. (5)TiO2. (x)Bi2O3 (x = 1, 2, 3, 4, and 5 mol%) have been produced and characterized using the related methods. Structural properties were investigated using X-ray diffraction (XRD) which confirms the non-crystalline structure and scanning electron microscopy (SEM) micrographs also confirm the XRD results. The energy dispersive X-ray (EDX) analysis profiles show that all the mentioned elements are present in the prepared glasses. Following the IR spectra, all the tellurium bonds such as stretching vibrations of TeO4 tbp and TeO3/TeO3+1 unit are revealed. Raman spectra confirm the presence of different functional groups, actually, it shows bands mainly in four spectral regions: R1 (65-150) cm-1, R2 (280-550) cm-1, R3 (880-950) cm-1 and R4 (916-926) cm-1 and the identified bands are assigned to respective molecular groups. The thermal study was carried out using Differential scanning calorimetry (DSC) which indicates good thermal stability of the synthesized glasses with increasing Bi concentration. From the optical absorption spectra, we evaluated cut-off edge wavelengths and found increasing cutoff wavelength with an increase in Bi2O3 concentration. In the UV-Visible region, optical band gap energy and allowed transitions were investigated using three methods; direct, indirect, and absorption spectrum fitting (ASF), and band gaps from indirect and ASF were matched.

Microporosity development in phenolic resin-based mesoporous carbons for enhancing CO2 adsorption at ambient conditions

NASA Astrophysics Data System (ADS)

Choma, Jerzy; Jedynak, Katarzyna; Fahrenholz, Weronika; Ludwinowicz, Jowita; Jaroniec, Mietek

2014-01-01

Soft-templating method was used to prepare mesoporous carbons. The synthesis in the presence of hydrochloric and citric acids involved resorcinol and formaldehyde as carbon precursors and triblock copolymer Pluronic F127 as a template. The as-synthesized samples underwent carbonization in flowing nitrogen at various temperatures; namely 600 °C, 700 °C and 800 °C. Two routes were used to develop microporosity in the mesoporous carbons studied. The first one involved introduction of tetraethyl orthosilicate to the reaction system. After silica dissolution with NaOH, an increase in microporosity was observed. The second method, chemical activation with KOH at 700 °C, was explored as an alternative approach to create microporosity. It is noteworthy that the TEOS addition not only led to the development of microporosity but also to some improvement of mesoporosity. The post-synthesis KOH activation resulted in more significant increase in the microporosity as compared to the samples obtained by TEOS-assisted synthesis. The mesopore volume was somewhat lower for activated carbons as compared to that in mesoporous carbons. Both methods resulted in micro-mesoporous carbons with good adsorption properties; for instance, in the case of carbons prepared in the presence of TEOS, the best sample exhibited BET surface area of 1463 m2/g and the total pore volume of 1.31 cm3/g. For the KOH activated carbons the best adsorption parameters were as follows: the specific surface area = 1906 m2/g, and the total pore volume = 0.98 cm3/g. Both procedures used for microporosity development afforded carbons with good adsorption properties that can be useful for applications such as CO2 adsorption, air and water purification.

Evaluation of BBL CHROMagar VanRE for detection of vancomycin-resistant Enterococci in rectal swab specimens.

PubMed

Stamper, Paul D; Shulder, Stephanie; Bekalo, Pearl; Manandhar, Deepika; Ross, Tracy L; Speser, Sharon; Kingery, Julie; Carroll, Karen C

2010-11-01

A study was performed on 517 surveillance rectal swabs to evaluate a selective and differential chromogenic medium, the BBL CHROMagar VanRE (CVRE), which enables recovery and identification of VanA- and VanB-containing Enterococcus faecium (ENFM) and Enterococcus faecalis (ENFS) isolates. Compared to BBL Enterococcosel agar, a bile-esculin-azide-vancomycin (BEAV) agar, the initial overall sensitivity, specificity, and positive and negative predictive values of CVRE for the detection of vancomycin-resistant ENFM and ENFS were 99.1% and 94.8% and 84.2% and 99.7%, respectively. Among our patient population, more vancomycin-resistant enterococci (VRE) were recovered with CVRE than BEAV.

Evaluation of BBL CHROMagar VanRE for Detection of Vancomycin-Resistant Enterococci in Rectal Swab Specimens▿

PubMed Central

Stamper, Paul D.; Shulder, Stephanie; Bekalo, Pearl; Manandhar, Deepika; Ross, Tracy L.; Speser, Sharon; Kingery, Julie; Carroll, Karen C.

2010-01-01

A study was performed on 517 surveillance rectal swabs to evaluate a selective and differential chromogenic medium, the BBL CHROMagar VanRE (CVRE), which enables recovery and identification of VanA- and VanB-containing Enterococcus faecium (ENFM) and Enterococcus faecalis (ENFS) isolates. Compared to BBL Enterococcosel agar, a bile-esculin-azide-vancomycin (BEAV) agar, the initial overall sensitivity, specificity, and positive and negative predictive values of CVRE for the detection of vancomycin-resistant ENFM and ENFS were 99.1% and 94.8% and 84.2% and 99.7%, respectively. Among our patient population, more vancomycin-resistant enterococci (VRE) were recovered with CVRE than BEAV. PMID:20739492

Exploring the Digital Natives among Pre-Service Teachers in Turkey: A Cross-Cultural Validation of the Digital Native Assessment Scale

ERIC Educational Resources Information Center

Teo, Timothy; Kabakçi Yurdakul, Isil; Ursavas, Ömer Faruk

2016-01-01

This study aims to explore the digital natives among a sample of pre-service teachers and in the process, examine the validity of a Turkish adaptation of the digital native assessment scale (DNAS) [Teo, T., & Fan, X. (2013). "Coefficient alpha and beyond: Issues and alternatives for educational research." "The Asia-Pacific…

Reflections on Basic Education under the "Three Guarantees" Policy in Tibet's Pastoral Districts

ERIC Educational Resources Information Center

Zhiyong, Zhu

2008-01-01

The "two exemptions and one subsidy" (TEOS) policy presages the coming of an era of free education in compulsory education. Actually, the agricultural and pastoral districts of China's Tibet Autonomous Region had already experienced policies of free compulsory education in the mid-1980s, that is, the "three guarantees"…

Human Systems Integration Requirements

DTIC Science & Technology

2009-09-01

52 Stratofortress, C/ KC -135 Stratotanker, E-3 Sentry and contractor logistics support aircraft; as well as a substantial jet engine inventory...www.hqda.army.mil/ teo /Sutability%20Terms%20MOA%20Oct%2005.pdf q. ISO 9241-11, Ergonomic requirements for office work with visual display terminals (VDTs

Water quality and mass transport in four watersheds in eastern Puerto Rico: Chapter E in Water quality and landscape processes of four watersheds in eastern Puerto Rico

USGS Publications Warehouse

Stallard, Robert F.; Murphy, Sheila F.; Murphy, Sheila F.; Stallard, Robert F.

2012-01-01

Water quality of four small watersheds in eastern Puerto Rico has been monitored since 1991 as part of the U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets program. These watersheds represent a montane, humid-tropical environment and differ in geology and land cover. Two watersheds are located on granitic rocks, and two are located on volcaniclastic rock. For each bedrock type, one watershed is covered with mature rainforest in the Luquillo Mountains, and the other watershed is undergoing reforestation after being affected by agricultural practices typical of eastern Puerto Rico. A subwatershed of the Icacos watershed, the Guabá, was also monitored to examine scaling effects. The water quality of the rivers draining forest, in the Icacos and Guabá (granitic watersheds) and Mameyes (a volcaniclastic watershed), show little contamination by human activities. The water is well oxygenated and has a nearly neutral pH, and nutrient concentrations are low. Concentrations of nutrients in the disturbed watersheds, the Cayaguás (granitic rock) and Canóvanas (volcaniclastic rock), are greater than in the forested watersheds, indicating some inputs from human activities. High in-stream productivity in the Canóvanas watershed leads to occasional oxygen and calcite supersaturation and carbon dioxide undersaturation. Suspended sediment concentrations in all watersheds are low, except during major storms. Most dissolved constituents derived from bedrock weathering or atmospheric deposition (including sodium, magnesium, calcium, silica, alkalinity, and chloride) decrease in concentration with increasing runoff, reflecting dilution from increased proportions of overland or near-surface flow. Strongly bioactive constituents (dissolved organic carbon, potassium, nitrate, ammonium ion, and phosphate) commonly display increasing concentration with increasing runoff, regardless of their ultimate origin (bedrock or atmosphere). The concentrations of many of the

JPRS Report, Soviet Union, Military Affairs

DTIC Science & Technology

1990-10-31

and for leaders of tions or arrests by the militia, drug addicts , alcoholics, soviet and State organs, enterprises, organizations, insti- etc. Would it...O.K. for a trial where the black whale -like humpbacks of the nuclear repairs erofint asand av teO. a trial submarines float high above the piers, are

What Made Your Essay Successful? I "T.A.C.K.L.E.D" the Essay Question!

ERIC Educational Resources Information Center

Teo, Tze Kwang

2015-01-01

Teaching in Singapore, Tze Kwang Teo cannot conceive of a history teacher unfamiliar with the mnemonic "PEE" (or "PEEL") used to structure students' essays. Its ubiquity is testimony to its power, reminding students both to explain and to substantiate their claims. Yet, as Foster and Gadd have argued, its neat formulation can…

Preparation and characterization of cellulose acetate organic/inorganic hybrid films

Treesearch

Saeed S. Shojaie; Timothy G. Rials; Stephen S. Kelley

1995-01-01

A series of organic/inorganic hybrid (OIH) films were prepared using cellulose acetate (CA) as the organic component and tetraethyl orthosilicate (TEOS) as the inorganic component. The chemical, morphological, and mechanical properties of these films were evaluated with a variety of analytical techniques. The results of these evaluations showed that crosslinked CA OIH...

Monodisperse mesoporous silica nanoparticles of distinct topology.

PubMed

Luo, Leilei; Liang, Yucang; Erichsen, Egil Sev; Anwander, Reiner

2017-06-01

Monodisperse and uniform high-quality MCM(Mobil Composition of Matter)-48-type CMSNs (Cubic Mesoporous Silica Nanoparticles) are readily prepared by simply optimizing the molar ratio of ethanol and surfactant in the system TEOS-CTAB-NaOH-H 2 O-EtOH (TEOS=tetraethyl orthosilicate, CTAB=cetyltrimethylammonium bromide, EtOH=ethanol). In the absence of ethanol only hexagonal mesoporous silica with ellipsoidal and spherical morphology are obtained. The presence of ethanol drives a mesophase transformation from hexagonal to mixed hexagonal/cubic, further to purely cubic, and finally to a mixed cubic/lamellar. This is accompanied by a morphology evolution involving a mixture of ellipses/spheres, regular rods, uniform spheres, and finally a mixture of spheres/flakes. Preserving the three-dimensional (3D) cubic MCM-48 structure, use of a small amount of ethanol is beneficial to the improvement of the monodispersity of the CMSNs. Moreover, the quality of the CMSNs can also be controlled by changing the surfactant concentration or adjusting the stirring rate. All MSNs were characterized using powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and N 2 physisorption, indicating highly long-range ordered pore arrays, high specific surface areas (max. 1173 m 2 g -1 ) as well as high pore volumes (max. 1.14 cm 3 g -1 ). The monodispersity of the CMSNs was verified by statistical particle size distribution from SEM (scanning electron microscopy)/TEM (transmission electron microscopy) images and DLS (dynamic light scattering). The mesophase transformation can be rationalized on the basis of an ethanol-driven change of the surfactant packing structure and charge matching at the surfactant/silicate interface. The corresponding morphology evolution can be elucidated by an ethanol-controlled hydrolysis rate of TEOS and degree of condensation of oligomeric silicate species via a nucleation and growth process. Copyright © 2017 Elsevier Inc. All

Ho3+-Yb3+ codoped tellurite based glasses in visible lasers and optical devices: Judd-Ofelt analysis and frequency upconversion

NASA Astrophysics Data System (ADS)

Azam, Mohd; Rai, Vineet Kumar

2017-04-01

The optical absorption and frequency upconversion emission in the Ho3+/Yb3+ codoped TeO2-ZnO (TZ), TeO2-ZnO-WO3 (TZW) and TeO2-ZnO-WO3-TiO2 (TZWTi) glasses prepared by melting and quenching method has been studied. Judd-Ofelt theory has been used to calculate the Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6), transition probabilities, radiative lifetimes, absorption cross sections and the branching ratios. Upconversion (UC) emission bands centered at ∼ 549 nm, ∼658 nm and ∼754 nm are observed upon 980 nm excitation. On codoping with the Yb3+ ions at 3.0 mol% the upconversion emission intensity enhancement of about ∼57 times, ∼342 times and ∼480 times for the green band whereas for the red band arising from the Ho3+ ions it is about ∼71 times, ∼438 times and ∼707 times respectively have been observed. The enhancement observed in the UC emission intensity is explained on the basis of efficient energy transfer from Yb3+ to Ho3+, larger absorption cross section, larger oscillator strengths and increase in the local field corrections factor. The spectroscopic quality factor Ω4/Ω6 has been calculated to get the information about the developed materials for laser applications. The upconversion emission cross section determined on the basis of Judd-Ofelt analysis is found to be maximum for Ho-Yb-TZWTi glass. The nephelauxetic ratio, bonding and covalency parameters have been calculated to know the nature of bonding between the rare earth ions and neighbouring oxygen atoms. The high color purity 83.8% has been reported in the codoped glasses at ∼81.2 W/cm2 pump power density.

Teacher Agency in the Performance of Inquiry-Oriented Science Curriculum Reform

ERIC Educational Resources Information Center

Oliveira, Alandeom W.

2012-01-01

In this commentary, I consider several theoretical and analytical aspects of Tang Wee Teo and Margery Osborne's case study. I begin by identifying structuralist and cultural themes in Tang Wee and Margery's theoretical model of human activity. Next, I offer an alternative interpretation for Tang Wee and Margery's reported findings in terms of the…

Misrecognition and Science Education Reform

ERIC Educational Resources Information Center

Brandt, Carol B.

2012-01-01

In this forum, I expand upon Teo and Osborne's discussion of teacher agency and curriculum reform. I take up and build upon their analysis to further examine one teacher's frustration in enacting an inquiry-based curriculum and his resulting accommodation of an AP curriculum. In this way I introduce the concept of misrecognition (Bourdieu and…

Hyperspectral Imaging and Obstacle Detection for Robotics Navigation

DTIC Science & Technology

2005-09-01

anatomy and diffraction process. 17 3.3 Technical Specifications of the System A. Brimrose AOTF Video Adaptor Specifications: Material TeO2 Active...sampled from glass case on person 2’s belt 530 pixels 20 pick-up white sampled from body panels of pick-up 600 pixels 21 pick-up blue sampled from

Highly Loaded Mesoporous Silica/Nanoparticle Composites and Patterned Mesoporous Silica Films

NASA Astrophysics Data System (ADS)

Kothari, Rohit; Hendricks, Nicholas R.; Wang, Xinyu; Watkins, James J.

2014-03-01

Novel approaches for the preparation of highly filled mesoporous silica/nanoparticle (MS/NP) composites and for the fabrication of patterned MS films are described. The incorporation of iron platinum NPs within the walls of MS is achieved at high NP loadings by doping amphiphilic poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (Pluronic®) copolymer templates via selective hydrogen bonding between the pre-synthesized NPs and the hydrophilic portion of the block copolymer. The MS is then synthesized by means of phase selective condensation of tetraethylorthosilicate (TEOS) within the NP loaded block copolymer templates dilated with supercritical carbon dioxide (scCO2) followed by calcination. For patterned films, microphase separated block copolymer/small molecule additive blends are patterned using UV-assisted nanoimprint lithography. Infusion and condensation of a TEOS within template films using ScCO2 as a processing medium followed by calcination yields the patterned MS films. Scanning electron microscopy is used characterize pattern fidelity and transmission electron microscopy analysis confirms the presence of the mesopores. Long range order in nanocomposites is confirmed by low angle x-ray diffraction.

CUORE: The Three Towers Test

NASA Astrophysics Data System (ADS)

Sparks, Laura; Goodsell, Alison

2009-11-01

Cryogenic Underground Observatory for Rare Events (CUORE) will be part of the next generation of detectors used to search for neutrinoless double beta decay (0vBB). Located in Assergi, Italy at the Gran Sasso National Laboratory (LNGS), CUORE will be a large cryogenic bolometer composed of 988 tellurium dioxide (TeO2) detectors with a total mass of 750 kg, and will search for 0vBB in 130Te. As the experiment will monitor the extremely rare event of 0vBB, all factors contributing to background need to be minimized to effectively increase the sensitivity. We assisted the LNGS researchers over the summer of 2008 by supporting Research and Development efforts to reduce the radioactive background of the experiment. Activities involved decontaminating the copper frame of radon daughters, and chemically etching and lapping the TeO2 crystals with nitric acid and silicon dioxide, respectively, to remove surface contaminants that contribute to background counts. This work was supported in part by NSF grant PHY-0653284 and the California State Faculty Support Grant.

Effects of treadmill training with the eyes closed on gait and balance ability of chronic stroke patients.

PubMed

Kim, Yong-Wook; Moon, Sung-Jun

2015-09-01

[Purpose] The purpose of this study was to compare the effect of treadmill walking with the eyes closed and open on the gait and balance abilities of chronic stroke patients. [Subjects and Methods] Thirty patients with chronic stroke participated in this study. The treadmill gait training for each group lasted 40 minutes, and sessions were held 3 times a week for 4 weeks. Gait ability was measured using a Biodex Gait Trainer Treadmill System. Balance ability was measured using a Biodex Balance System. [Results] After the treadmill training' the treadmill training with eyes closed (TEC) group showed significant improvements in walking distance' step length' coefficient of variation' and limit of stability (overall' lateral affected' forward lateral unaffected) compared to the treadmill training with eyes open (TEO) group. [Conclusion] The walking and balance abilities of the TEC participants showed more improvement after the treadmill walking sessions than those of the TEO participants. Therefore' treadmill walking with visual deprivation may be useful for the rehabilitation of patients with chronic stroke.

Constructing dual-defense mechanisms on membrane surfaces by synergy of PFSA and SiO2 nanoparticles for persistent antifouling performance

NASA Astrophysics Data System (ADS)

Zhou, Linjie; Gao, Kang; Jiao, Zhiwei; Wu, Mengyuan; He, Mingrui; Su, Yanlei; Jiang, Zhongyi

2018-05-01

Synthetic antifouling membrane surfaces with dual-defense mechanisms (fouling-resistant and fouling-release mechanism) were constructed through the synergy of perfluorosulfonic acid (PFSA) and SiO2 nanoparticles. During the nonsolvent induced phase separation (NIPS) process, the amphiphilic PFSA polymers spontaneously segregated to membrane surfaces and catalyzed the hydrolysis-polycondensation of tetraethyl orthosilicate (TEOS) to generate hydrophilic SiO2 nanoparticles (NPs). The resulting PVDF/PFSA/SiO2 hybrid membranes were characterized by contact angle measurements, FTIR, XPS, SEM, AFM, TGA, and TEM. The hydrophilic microdomains and low surface energy microdomains of amphiphilic PFSA polymers respectively endowed membrane surfaces with fouling-resistant mechanism and fouling-release mechanism, while the hydrophilic SiO2 NPs intensified the fouling-resistant mechanism. When the addition of TEOS reached 3 wt%, the hybrid membrane with optimal synergy of PFSA and SiO2 NPs displayed low flux decline (17.4% DRt) and high flux recovery (99.8% FRR) during the filtration of oil-in-water emulsion. Meanwhile, the long-time stability test verified that the hybrid membrane possessed persistent antifouling performance.

Waste form evaluation for RECl 3 and REO x fission products separated from used electrochemical salt

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

Riley, Brian J.; Pierce, David A.; Crum, Jarrod V.

The work presented here is based off the concept that the rare earth chloride (RECl3) fission products mixture within the used electrorefiner (ER) salt can be selectively removed as RECl3 (not yet demonstrated) or precipitated out as REOCl through oxygen sparging (has been demonstrated). This paper presents data showing the feasibility of immobilizing a mixture of RECl3’s at 10 mass% into a TeO2-PbO glass and it shows that this same mixture of RECl3’s can be oxidized to REOCl at 300°C and then to REOx by 1200°C. When the REOx mixture is heated at temperatures >1200°C, the ratios of REOx’s change.more » The mixture of REOx was then immobilized in a LABS glass at a high loading of 60 mass%. Both the TeO2-PbO glass and LABS glass systems show good chemical durability. The advantages and disadvantages of tellurite and LABS glasses are compared.« less

Preparation and characterization of chain-like and peanut-like Fe3O4@SiO2 core-shell structure.

PubMed

Shi, Haowei; Huang, Yan; Cheng, Chao; Ji, Guoyuan; Yang, Yuxiang; Yuan, Hongming

2013-10-01

The size- and shape-controlled Fe3O4@SiO2 nanocomposites were successfully synthesized via the sol-gel method. The results showed that the size, shape, and property of the products were directly influenced by the amount of TEOS, and the concentration of water-based magnetic fluid in the coating process. The morphology and properties of the products were characterized by TEM, SEM, X-ray powder diffraction, IR and EDS. The Fe3O4@SiO2 composites with easily-controlled size arranged from 58 to 835 nm could be synthesized by adjusting the experimental parameters. When TEOS amount is 1 mL and the concentration of magnetic fluid were 30.0 and 10.0 mg/mL respectively, chain-like and peanuts-like well-dispersed Fe3O4@SiO2 particles with clear core-shell structure were obtained. These size- and shape-controlled Fe3O4@SiO2 composites may have potential application in the field of targeted drug delivery and MRI contrast agent.

Magnetostriction-polarization coupling in multiferroic Mn 2MnWO 6

DOE PAGES

Li, Man-Rong; McCabe, Emma E.; Stephens, Peter W.; ...

2017-12-11

Double corundum-related polar magnets are promising materials for multiferroic and magnetoelectric applications in spintronics. However, their design and synthesis is a challenge, and magnetoelectric coupling has only been observed in Ni 3TeO 6 among the known double corundum compounds to date. Here in this paper we address the high-pressure synthesis of a new polar and antiferromagnetic corundum derivative Mn 2MnWO 6, which adopts the Ni 3TeO 6-type structure with low temperature first-order field-induced metamagnetic phase transitions (T N = 58 K) and high spontaneous polarization (~ 63.3 μC·cm -2). The magnetostriction-polarization coupling in Mn 2MnWO 6 is evidenced by secondmore » harmonic generation effect, and corroborated by magnetic-field-dependent pyroresponse behavior, which together with the magnetic-field-dependent polarization and dielectric measurements, qualitatively indicate magnetoelectric coupling. Finally, piezoresponse force microscopy imaging and spectroscopy studies on Mn 2MnWO 6 show switchable polarization, which motivates further exploration on magnetoelectric effect in single crystal/thin film specimens.« less

Magnetostriction-polarization coupling in multiferroic Mn 2MnWO 6

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

Li, Man-Rong; McCabe, Emma E.; Stephens, Peter W.

Double corundum-related polar magnets are promising materials for multiferroic and magnetoelectric applications in spintronics. However, their design and synthesis is a challenge, and magnetoelectric coupling has only been observed in Ni 3TeO 6 among the known double corundum compounds to date. Here in this paper we address the high-pressure synthesis of a new polar and antiferromagnetic corundum derivative Mn 2MnWO 6, which adopts the Ni 3TeO 6-type structure with low temperature first-order field-induced metamagnetic phase transitions (T N = 58 K) and high spontaneous polarization (~ 63.3 μC·cm -2). The magnetostriction-polarization coupling in Mn 2MnWO 6 is evidenced by secondmore » harmonic generation effect, and corroborated by magnetic-field-dependent pyroresponse behavior, which together with the magnetic-field-dependent polarization and dielectric measurements, qualitatively indicate magnetoelectric coupling. Finally, piezoresponse force microscopy imaging and spectroscopy studies on Mn 2MnWO 6 show switchable polarization, which motivates further exploration on magnetoelectric effect in single crystal/thin film specimens.« less

Evaluation of a New System, VITEK 2, for Identification and Antimicrobial Susceptibility Testing of Enterococci

PubMed Central

Garcia-Garrote, Fernando; Cercenado, Emilia; Bouza, Emilio

2000-01-01

We evaluated the new automated VITEK 2 system (bioMérieux) for the identification and antimicrobial susceptibility testing of enterococci. The results obtained with the VITEK 2 system were compared to those obtained by reference methods: standard identification by the scheme of Facklam and Sahm [R. R. Facklam and D. F. Sahm, p. 308–314, in P. R. Murray et al., ed., Manual of Clinical Microbiology, 6th ed., 1995] and with the API 20 STREP system and, for antimicrobial susceptibility testing, broth microdilution and agar dilution methods by the procedures of the National Committee for Clinical Laboratory Standards. The presence of vanA and vanB genes was determined by PCR. A total of 150 clinical isolates were studied, corresponding to 60 Enterococcus faecalis, 55 Enterococcus faecium, 26 Enterococcus gallinarum, 5 Enterococcus avium, 2 Enterococcus durans, and 2 Enterococcus raffinosus isolates. Among those isolates, 131 (87%) were correctly identified to the species level with the VITEK 2 system. Approximately half of the misidentifications were for E. faecium with low-level resistance to vancomycin, identified as E. gallinarum or E. casseliflavus; however, a motility test solved the discrepancies and increased the agreement to 94%. Among the strains studied, 66% were vancomycin resistant (57 VanA, 16 VanB, and 26 VanC strains), 23% were ampicillin resistant (MICs, ≥16 μg/ml), 31% were high-level gentamicin resistant, and 45% were high-level streptomycin resistant. Percentages of agreement for susceptibility and resistance to ampicillin, vancomycin, and teicoplanin and for high-level gentamicin resistance and high-level streptomycin resistance were 93, 95, 97, 97, and 96%, respectively. The accuracy of identification and antimicrobial susceptibility testing of enterococci with the VITEK 2 system, together with the significant reduction in handling time, will have a positive impact on the work flow of the clinical microbiology laboratory. PMID:10834961

Evaluation of the Verigene Gram-Positive Blood Culture Nucleic Acid Test for Rapid Detection of Bacteria and Resistance Determinants

PubMed Central

Wojewoda, Christina M.; Sercia, Linda; Navas, Maria; Tuohy, Marion; Wilson, Deborah; Hall, Geraldine S.; Procop, Gary W.

2013-01-01

Rapid identification of pathogens from blood cultures can decrease lengths of stay and improve patient outcomes. We evaluated the accuracy of the Verigene Gram-positive blood culture (BC-GP) nucleic acid test for investigational use only (Nanosphere, Inc., Northbrook, IL) for the identification of Gram-positive bacteria from blood cultures. The detection of resistance genes (mecA in Staphylococcus aureus and Staphylococcus epidermidis and vanA or vanB in Enterococcus faecium and Enterococcus faecalis) by the BC-GP assay also was assessed. A total of 186 positive blood cultures (in BacT/Alert FA bottles) with Gram-positive cocci observed with Gram staining were analyzed using the BC-GP assay. The BC-GP results were compared with the identification and susceptibility profiles obtained with routine methods in the clinical laboratory. Discordant results were arbitrated with additional biochemical, cefoxitin disk, and repeat BC-GP testing. The initial BC-GP organism identification was concordant with routine method results for 94.6% of the blood cultures. Only 40% of the Streptococcus pneumoniae identifications were correct. The detection of the mecA gene for 69 blood cultures with only S. aureus or S. epidermidis was concordant with susceptibility testing results. For 3 of 6 cultures with multiple Staphylococcus spp., mecA detection was reported but was correlated with oxacillin resistance in a species other than S. aureus or S. epidermidis. The detection of vanA agreed with susceptibility testing results for 45 of 46 cultures with E. faecalis or E. faecium. Comparison of the mean times to results for each organism group showed that BC-GP results were available 31 to 42 h earlier than phenotypic identifications and 41 to 50 h earlier than susceptibility results. PMID:23596240

Complex Routes of Nosocomial Vancomycin-Resistant Enterococcus faecium Transmission Revealed by Genome Sequencing.

PubMed

Raven, Kathy E; Gouliouris, Theodore; Brodrick, Hayley; Coll, Francesc; Brown, Nicholas M; Reynolds, Rosy; Reuter, Sandra; Török, M Estée; Parkhill, Julian; Peacock, Sharon J

2017-04-01

Vancomycin-resistant Enterococcus faecium (VREfm) is a leading cause of nosocomial infection. Here, we describe the utility of whole-genome sequencing in defining nosocomial VREfm transmission. A retrospective study at a single hospital in the United Kingdom identified 342 patients with E. faecium bloodstream infection over 7 years. Of these, 293 patients had a stored isolate and formed the basis for the study. The first stored isolate from each case was sequenced (200 VREfm [197 vanA, 2 vanB, and 1 isolate containing both vanA and vanB], 93 vancomycin-susceptible E. faecium) and epidemiological data were collected. Genomes were also available for E. faecium associated with bloodstream infections in 15 patients in neighboring hospitals, and 456 patients across the United Kingdom and Ireland. The majority of infections in the 293 patients were hospital-acquired (n = 249) or healthcare-associated (n = 42). Phylogenetic analysis showed that 291 of 293 isolates resided in a hospital-associated clade that contained numerous discrete clusters of closely related isolates, indicative of multiple introductions into the hospital followed by clonal expansion associated with transmission. Fine-scale analysis of 6 exemplar phylogenetic clusters containing isolates from 93 patients (32%) identified complex transmission routes that spanned numerous wards and years, extending beyond the detection of conventional infection control. These contained both vancomycin-resistant and -susceptible isolates. We also identified closely related isolates from patients at Cambridge University Hospitals NHS Foundation Trust and regional and national hospitals, suggesting interhospital transmission. These findings provide important insights for infection control practice and signpost areas for interventions. We conclude that sequencing represents a powerful tool for the enhanced surveillance and control of nosocomial E. faecium transmission and infection. © The Author 2017. Published by Oxford

Comparison of PCR/electron spray ionization-time-of-flight-mass spectrometry versus traditional clinical microbiology for active surveillance of organisms contaminating high-use surfaces in a burn intensive care unit, an orthopedic ward and healthcare workers.

PubMed

Yun, Heather C; Kreft, Rachael E; Castillo, Mayra A; Ehrlich, Garth D; Guymon, Charles H; Crouch, Helen K; Chung, Kevin K; Wenke, Joseph C; Hsu, Joseph R; Spirk, Tracy L; Costerton, J William; Mende, Katrin; Murray, Clinton K

2012-10-10

Understanding nosocomial pathogen transmission is restricted by culture limitations. Novel platforms, such as PCR-based electron spray ionization-time-of-flight-mass spectrometry (ESI-TOF-MS), may be useful as investigational tools. Traditional clinical microbiology (TCM) and PCR/ESI-TOF-MS were used to recover and detect microorganisms from the hands and personal protective equipment of 10 burn intensive care unit (ICU) healthcare workers providing clinical care at a tertiary care military referral hospital. High-use environmental surfaces were assessed in 9 burn ICU and 10 orthopedic patient rooms. Clinical cultures during the study period were reviewed for pathogen comparison with investigational molecular diagnostic methods. From 158 samples, 142 organisms were identified by TCM and 718 by PCR/ESI-TOF-MS. The molecular diagnostic method detected more organisms (4.5 ± 2.1 vs. 0.9 ± 0.8, p < 0.01) from 99% vs. 67% of samples (p < 0.01). TCM detected S. aureus in 13 samples vs. 21 by PCR/ESI-TOF-MS. Gram-negative organisms were less commonly identified than gram-positive by both methods; especially by TCM. Among all detected bacterial species, similar percentages were typical nosocomial pathogens (18-19%) for TCM vs. PCR/ESI-TOF-MS. PCR/ESI-TOF-MS also detected mecA in 112 samples, vanA in 13, and KPC-3 in 2. MecA was associated (p < 0.01) with codetection of coagulase negative staphylococci but not S. aureus. No vanA was codetected with enterococci; one KPC-3 was detected without Klebsiella spp. In this pilot study, PCR/ESI-TOF-MS detected more organisms, especially gram-negatives, compared to TCM, but the current assay format is limited by the number of antibiotic resistance determinants it covers. Further large-scale assessments of PCR/ESI-TOF-MS for hospital surveillance are warranted.

Development of a Real-Time PCR Protocol Requiring Minimal Handling for Detection of Vancomycin-Resistant Enterococci with the Fully Automated BD Max System.

PubMed

Dalpke, Alexander H; Hofko, Marjeta; Zimmermann, Stefan

2016-09-01

Vancomycin-resistant enterococci (VRE) are an important cause of health care-associated infections, resulting in significant mortality and a significant economic burden in hospitals. Active surveillance for at-risk populations contributes to the prevention of infections with VRE. The availability of a combination of automation and molecular detection procedures for rapid screening would be beneficial. Here, we report on the development of a laboratory-developed PCR for detection of VRE which runs on the fully automated Becton Dickinson (BD) Max platform, which combines DNA extraction, PCR setup, and real-time PCR amplification. We evaluated two protocols: one using a liquid master mix and the other employing commercially ordered dry-down reagents. The BD Max VRE PCR was evaluated in two rounds with 86 and 61 rectal elution swab (eSwab) samples, and the results were compared to the culture results. The sensitivities of the different PCR formats were 84 to 100% for vanA and 83.7 to 100% for vanB; specificities were 96.8 to 100% for vanA and 81.8 to 97% for vanB The use of dry-down reagents and the ExK DNA-2 kit for extraction showed that the samples were less inhibited (3.3%) than they were by the use of the liquid master mix (14.8%). Adoption of a cutoff threshold cycle of 35 for discrimination of vanB-positive samples allowed an increase of specificity to 87.9%. The performance of the BD Max VRE assay equaled that of the BD GeneOhm VanR assay, which was run in parallel. The use of dry-down reagents simplifies the assay and omits any need to handle liquid PCR reagents. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Isolation and Biochemical Fingerprinting of Vancomycin-Resistant Enterococcus faecium From Meat, Chicken and Cheese.

PubMed

Talebi, Malihe; Sadeghi, Javad; Rahimi, Fateh; Pourshafie, Mohammad Reza

2015-04-01

Vancomycin-resistant enterococci (VRE) are important nosocomial pathogens and food chain has been considered as an assumed source for dissemination of VRE to human. The presence of VRE isolates from food samples and typing of these isolates with Phene plate, a biochemical fingerprinting method, were investigated. Thirty samples of meat, chicken and cheese were analyzed for VRE during 2010. Antibiotic susceptibility tests and minimum inhibitory concentration (MIC) were also examined. VRE isolates were typed with the Phene plate system (PhPlate), a biochemical fingerprinting method. A total of 70 VRE isolates were obtained and identified as Enterococcus faecium by species-specific PCR. All the isolates carried vanA, while none of them harbored vanB. The VRE isolates included 35, 27, and 8 isolates from meat, chicken and cheese, respectively. Typing with the PhPlate revealed a diversity index of 0.78 for E. faecium, containing 10 common and four single types. The results of antibiotic susceptibility and MIC tests showed an increased resistance to ciprofloxacin, erythromycin, ampicillin and gentamicin, to which, 100%, 100%, 100%, and 95% of VRE isolates were resistant, respectively. Only 5% of the isolates were resistant to chloramphenicol and the MIC of the isolates for vancomycin and teicoplanin was ≥ 256 µg/mL and for gentamicin-resistant isolates it was 1024 µg/mL. Conventional and molecular identification tests exhibited that all the isolates were E. faecium carrying vanA. None of the isolates harbored vanB. The results showed that enterococci are common contaminants in food. Indeed, this study indicates a high prevalence of multidrug-resistant enterococci in food of animal origin in Iran. Isolating some persisting enterococcal isolates revealed that continuous surveillance of antimicrobial resistance in enterococci from food is essential.

Molecular epidemiology of vancomycin-resistant enterococcal bacteraemia: results from the Canadian Nosocomial Infection Surveillance Program, 1999-2009.

PubMed

McCracken, M; Wong, A; Mitchell, R; Gravel, D; Conly, J; Embil, J; Johnston, L; Matlow, A; Ormiston, D; Simor, A E; Smith, S; Du, T; Hizon, R; Mulvey, M R

2013-07-01

Vancomycin-resistant enterococci (VRE) can be associated with serious bacteraemia. The focus of this study was to characterize the molecular epidemiology of VRE from bacteraemia cases that were isolated from 1999 to 2009 as part of Canadian Nosocomial Infection Surveillance Program (CNISP) surveillance activities. From 1999 to 2009, enterococci were collected from across Canada in accordance with the CNISP VRE surveillance protocol. MICs were determined using broth microdilution. PCR was used to identify vanA, B, C, D, E, G and L genes. Genetic relatedness was examined using multilocus sequence typing (MLST). A total of 128 cases of bacteraemia were reported to CNISP from 1999 to 2009. In 2007, a significant increase in bacteraemia rates was observed in western and central Canada. Eighty-one of the 128 bacteraemia isolates were received for further characterization and were identified as Enterococcus faecium. The majority of isolates were from western Canada (60.5%), followed by central (37.0%) and eastern (2.5%) Canada. Susceptibilities were as follows: daptomycin, linezolid, tigecycline and chloramphenicol, 100%; quinupristin/dalfopristin, 96.3%; high-level gentamicin, 71.6%; tetracycline, 50.6%; high-level streptomycin, 44.4%; rifampicin, 21.0%; nitrofurantoin, 11.1%; clindamycin, 8.6%; ciprofloxacin, levofloxacin and moxifloxacin, 1.2%; and ampicillin, 0.0%. vanA contributed to vancomycin resistance in 90.1% of isolates and vanB in 9.9%. A total of 17 sequence types (STs) were observed. Beginning in 2006 there was a shift in ST from ST16, ST17, ST154 and ST80 to ST18, ST412, ST203 and ST584. The increase in bacteraemia observed since 2007 in western and central Canada appears to coincide with the shift of MLST STs. All VRE isolates remained susceptible to daptomycin, linezolid, chloramphenicol and tigecycline.

Evaluation of the Verigene Gram-positive blood culture nucleic acid test for rapid detection of bacteria and resistance determinants.

PubMed

Wojewoda, Christina M; Sercia, Linda; Navas, Maria; Tuohy, Marion; Wilson, Deborah; Hall, Geraldine S; Procop, Gary W; Richter, Sandra S

2013-07-01

Rapid identification of pathogens from blood cultures can decrease lengths of stay and improve patient outcomes. We evaluated the accuracy of the Verigene Gram-positive blood culture (BC-GP) nucleic acid test for investigational use only (Nanosphere, Inc., Northbrook, IL) for the identification of Gram-positive bacteria from blood cultures. The detection of resistance genes (mecA in Staphylococcus aureus and Staphylococcus epidermidis and vanA or vanB in Enterococcus faecium and Enterococcus faecalis) by the BC-GP assay also was assessed. A total of 186 positive blood cultures (in BacT/Alert FA bottles) with Gram-positive cocci observed with Gram staining were analyzed using the BC-GP assay. The BC-GP results were compared with the identification and susceptibility profiles obtained with routine methods in the clinical laboratory. Discordant results were arbitrated with additional biochemical, cefoxitin disk, and repeat BC-GP testing. The initial BC-GP organism identification was concordant with routine method results for 94.6% of the blood cultures. Only 40% of the Streptococcus pneumoniae identifications were correct. The detection of the mecA gene for 69 blood cultures with only S. aureus or S. epidermidis was concordant with susceptibility testing results. For 3 of 6 cultures with multiple Staphylococcus spp., mecA detection was reported but was correlated with oxacillin resistance in a species other than S. aureus or S. epidermidis. The detection of vanA agreed with susceptibility testing results for 45 of 46 cultures with E. faecalis or E. faecium. Comparison of the mean times to results for each organism group showed that BC-GP results were available 31 to 42 h earlier than phenotypic identifications and 41 to 50 h earlier than susceptibility results.

Clinical relevance of molecular identification of microorganisms and detection of antimicrobial resistance genes in bloodstream infections of paediatric cancer patients.

PubMed

Carlesse, Fabianne; Cappellano, Paola; Quiles, Milene Gonçalves; Menezes, Liana Carballo; Petrilli, Antonio Sérgio; Pignatari, Antonio Carlos

2016-09-01

Bloodstream infections (BSIs) are the major cause of mortality in cancer patients. Molecular techniques are used for rapid diagnosis of BSI, allowing early therapy and improving survival. We aimed to establish whether real-time quantitative polymerase chain reaction (qPCR) could improve early diagnosis and therapy in paediatric cancer patients, and describe the predominant pathogens of BSI and their antimicrobial susceptibility. Blood samples were processed by the BACTEC system and microbial identification and susceptibility tests were performed by the Phoenix system. All samples were screened by multiplex 16 s rDNA qPCR. Seventeen species were evaluated using sex-specific TaqMan probes and resistance genes blaSHV, blaTEM, blaCTX, blaKPC, blaIMP, blaSPM, blaVIM, vanA, vanB and mecA were screened by SYBR Green reactions. Therapeutic efficacy was evaluated at the time of positive blood culture and at final phenotypic identification and antimicrobial susceptibility results. We analyzed 69 episodes of BSI from 64 patients. Gram-positive bacteria were identified in 61 % of the samples, Gram-negative bacteria in 32 % and fungi in 7 %. There was 78.2 % of agreement between the phenotypic and molecular methods in final species identification. The mecA gene was detected in 81.4 % of Staphylococcus spp., and 91.6 % were concordant with the phenotypic method. Detection of vanA gene was 100 % concordant. The concordance for Gram-negative susceptibilities was 71.4 % for Enterobacteriaceae and 50 % for Pseudomonas aeruginosa. Therapy was more frequently inadequate in patients who died, and the molecular test was concordant with the phenotypic susceptibility test in 50 %. qPCR has potential indication for early identification of pathogens and antimicrobial resistance genes from BSI in paediatric cancer patients and may improve antimicrobial therapy.

Capillary electrophoresis method for the discrimination between natural and artificial vanilla flavor for controlling food frauds.

PubMed

Lahouidak, Samah; Salghi, Rachid; Zougagh, Mohammed; Ríos, Angel

2018-03-06

A capillary electrophoresis method was developed for the determination of coumarin (COUM), ethyl vanillin (EVA), p-hydroxybenzaldehyde (PHB), p-hydroxybenzoic acid (PHBA), vanillin (VAN), vanillic acid (VANA) and vanillic alcohol (VOH) in vanilla products. The measured concentrations are compared to values obtained by liquid chromatography (LC) method. Analytical results, method precision, and accuracy data are presented and limits of detection for the method ranged from 2 to 5 μg/mL. The results obtained are used in monitoring the composition of vanilla flavorings, as well as for confirmation of natural or non-natural origin of vanilla in samples using four selected food samples containing this flavor. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Advanced Research into Moving Target Imaging Using Multistatic Radar

DTIC Science & Technology

2009-12-01

1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188...11 C. TEO BENG KOON WILLIAM’S WORK..................................................12 III. DATA ANALYSIS... principles of electromagnetic and radar theory rely on the Maxwell’s equations. Radar theory is a practical expansion of the fundamental theory of

Proceedings of the Complex Systems Engineering Synthesis and Assessment Technology Workshop Held in Silver Spring, Maryland on 20-24 July 1992

DTIC Science & Technology

1992-07-24

Pmo Pbuf Tarr PenvTmm Patneo TTneo Teo Pateo ’,- r 0,Traneo 8 a e P naco Pfa Te aco Tsro- - PPatnen Them, Teyn Pate.. ••==P a• Tat e,- Fr ti I 3 456...Trivedi. Reliability modeling using SHARPE. IEEE Trans. Reliability, R-36(2):186-193, June 1987. 3 [14] K. Salem and H. Garcia-Molina. Disk striping

Establishing a Deradicalization/Disengagement Model for America’s Correctional Facilities: Recommendations for Countering Prison Radicalization

DTIC Science & Technology

2013-03-01

Singaporeans on the ISA,” Malaysian Business, October 1, 2011, 56. 121 “Parliamentary Speech on the Internal Security Act—Speech by Mr Teo Chee Hean...Nanyang Technological University , Singapore and the Religious Rehabilitation Group (RRG), Singapore: S. Rajarathnam School of International Studies... University , Singapore and the Religious Rehabilitation Group (RRG). Singapore: S. Rajarathnam School of International Studies, 2009. http

Simple, Fast, and Sensitive Method for Quantification of Tellurite in Culture Media▿

PubMed Central

Molina, Roberto C.; Burra, Radhika; Pérez-Donoso, José M.; Elías, Alex O.; Muñoz, Claudia; Montes, Rebecca A.; Chasteen, Thomas G.; Vásquez, Claudio C.

2010-01-01

A fast, simple, and reliable chemical method for tellurite quantification is described. The procedure is based on the NaBH4-mediated reduction of TeO32− followed by the spectrophotometric determination of elemental tellurium in solution. The method is highly reproducible, is stable at different pH values, and exhibits linearity over a broad range of tellurite concentrations. PMID:20525868

Defense Small Business Innovation Research Program (SBIR). Volume 1. Army Abstracts of Phase 1 Awards 1993

DTIC Science & Technology

1993-01-01

glass phase transformations, will identify characteristic signatures associated with film formation. Phase I technical objectives include the analysis...Fast, Highly Sensitive, Rugged, Miniature Spectroradiometer Based on a TeO2 Acousto-optic Tunable Filter (AOTF) Abstract: Brimrose proposes to research...this problem. The use of poltruded glass fiber reinforcing elements containing recycled plastic in their matrices will also be examined as this will

Spectral and Polarimetric Analysis of Hyperspectral Data Collected by an Acousto-Optic Tunable Filter System

DTIC Science & Technology

1993-09-23

dioxide ( TeO2 ) crystal which splits a beam of light entering the sensor into a set of two narrow band, orthogonally polarized images for each...See Figure 3) These laws hold true for Light ry V m .Li t ray , &o r air RefairRefractive lade: a, )’i i .- t 1 V Refractive inaex n’ Glass or

The Framework for an Information Technology Strategic Roadmap for the United States Marine Corps: How Current Acquisitions Align to the Current Strategic Direction of the Department of Defense, Department of the Navy, and United States Marine Corps

DTIC Science & Technology

2008-06-01

PAGE INTENTIONALLY LEFT BLANK xv ACKNOWLEDGMENTS We would like to thank Mr. Clint Swett (Director, Technology Services Organization, DFAS- KC ) and...Major Jeffrey Thiry (Deputy Director, Technology Services Organization, DFAS- KC ) for their help and support. Their guidance proved invaluable in... Teo (1996) define alignment as the “coordination between the business and IS planning functions and activities”. Luftman, Papp and Brier (1999

Pro-lipogenic Action of Lysophosphatidic Acid in Ovarian Cancer

DTIC Science & Technology

2014-04-01

Function. IUBMB Life. 2008. 60: 347-354. 11. Tse C, Shoemaker AR, Adickes J, Anderson MG, Chen J, Jin S, Johnson EF, Marsh KC , Mitten MJ, Nimmer P...Ann. Oncol. 9, 437–442 14. Choi, J. W., Herr, D. R., Noguchi, K., Yung, Y. C., Lee, C. W., Mutoh, T., Lin, M. E., Teo , S. T., Park, K. E., Mosley, A

Mesoporous silica obtained with methyltriethoxysilane as co-precursor in alkaline medium

NASA Astrophysics Data System (ADS)

Putz, Ana-Maria; Wang, Kunzhou; Len, Adél; Plocek, Jiri; Bezdicka, Petr; Kopitsa, Gennady P.; Khamova, Tamara V.; Ianăşi, Cătălin; Săcărescu, Liviu; Mitróová, Zuzana; Savii, Cecilia; Yan, Minhao; Almásy, László

2017-12-01

Mesoporous silica particles have been synthesized by sol-gel method from tetraethoxysilane (tetraethylorthosilicate, TEOS) and methyltriethoxysilane (MTES), in ethanol and water mixture, at different ratios of the of the silica precursors. Ammonia was used as catalyst at room temperature and hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, CTAB) as the structure directing agent. Nitrogen sorption, X-ray diffraction and small-angle neutron scattering gave information on the evolution of the gel structure and pore morphologies in the function of MTES/TEOS molar ratio. Thermogravimetric and differential thermal analysis showed that with addition of MTES the exothermic peak indicating the oxidation of the low molecular weight organic fragments shift to higher temperature. A room-temperature, one-pot synthesis of MCM-41 type materials is presented, in which the variation of the MTES concentration allows to change the hydrophobicity, preserving the specific properties materials, like the ordered pore structure, large specific surface area and high porosity. Specifically, the obtained materials had cylindrical pores, specific surface areas up to 1101 m2/g and total pore volumes up to 0.473 cm3/g. The obtained mesoporous materials are susceptible for further functionalization to improve their selective uptake of guest species in drug delivery applications.

WE-D-BRB-02: Proton Treatment Planning and Beam Optimization

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

Pankuch, M.

2016-06-15

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. Itmore » introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy. B. Teo, B.K Teo had received travel funds from IBA in 2015.« less

Waste form evaluation for RECl 3 and REO x fission products separated from used electrochemical salt

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

Riley, Brian J.; Pierce, David A.; Crum, Jarrod V.

The work presented here is based off the concept that the rare earth chloride (RECl 3) fission products within the used electrorefiner (ER) salt can be selectively removed as RECl 3 (not yet demonstrated) or precipitated out as a mixture of REOCl and REO x through oxygen sparging (has been demonstrated). This paper presents data showing the feasibility of immobilizing a mixture of RECl 3s at 10 mass% into a 78%TeO 2-22%PbO glass while also showing that this same mixture of RECl 3s can be oxidized to REOCl at 300 °C and then to REO x by 1200 °C, evolvingmore » Cl 2(g). When the REO x mixture is heated at temperatures >1200 °C, the ratios of REO xs change. The mixture of REO x was then immobilized in a lanthanide borosilicate (LABS) glass at a high loading of 60 mass%. Both the 78%TeO 2-22%PbO glass and LABS glass systems show good chemical durability. In conclusion, the advantages and disadvantages of tellurite and LABS glasses are compared.« less

[Preparation of large-pore silica microspheres using templating method and their applications to protein separation with high performance liquid chromatography].

PubMed

Niu, Mengna; Ma, Hongyan; Hu, Fei; Wang, Shige; Liu, Lu; Chang, Haizhou; Huang, Mingxian

2017-06-08

Large-pore silica microspheres were synthesized by utilizing weak cation exchange polymer beads as templates, N -trimethoxysilylpropyl- N,N,N -trimethylammonium chloride (TMSPTMA) as a structure-directing agent, tetraethoxysilane (TEOS) as a silica precursor, and triethanolamine as a weak base catalyst. The hydrolysis and condensation of the silica precursors occurred inside the templating polymer beads yielded polymer/silica composite microspheres. After the organic polymer templates were removed in the calcination step, large-pore silica microspheres were produced. The effects of different reaction conditions on the morphology, structure and dispersibility of the formed silica microspheres were investigated. It has been shown that when the volume ratio of TMSPTMA, TEOS and triethanolamine was 1:2:2, silica microspheres with pore size range of 50-150 nm and particle size around 2 μm were obtained. The as-prepared silica microspheres were then bonded with chlorodimethyloctadecylsilane (C18), packed into a 50 mm×4.6 mm column, and evaluated for the separations of some common standard proteins and soybean isolation proteins. The results showed that the large-pore silica spheres from this work have potentials for protein separation in HPLC.

Preliminary results on the search for the neutrinoless double beta decay of 130Te with the cuoricino experiment

DOE PAGES

Nucciotti, A.

2003-11-18

The search for neutrinoless double beta decay (DBD-0ν) is a powerful tool to establish the correct neutrino mass hierarchy and whether the neutrino is a Majorana or Dirac particle. The Milano group has run several experiments using thermal detectors to search for the 130Te DBD-0ν. The Cuoricino experiment consists of an array of 62 TeO 2 thermal detectors for a total mass of about 40 kg, by far the largest cryogenic experiment in the world. The detector installation in the Gran Sasso Underground Laboratory has been recently completed. After a test phase the experiment is now taking data and wemore » report here the preliminary results. In conclusion, Cuoricino is the first step toward the CUORE experiment, which will consists of 1000 TeO 2 thermal detectors for a total mass of about 760 kg: in this paper we discuss also the physics potential of both stages for what concerns the DBD-0ν search. PACS: 11.30.Fs Lepton number – 14.60.Pq Neutrino mass and mixing – 23.40.Bw Weak interactions in beta decay« less

A New Route to Liposil Formation by an Interfacial Sol-Gel Process Confined by Lipid Bilayer.

PubMed

Shen, Shukun; Yang, Lu; Lu, Yaxing; Chen, Jian-Gang; Song, Shaofei; Hu, Daodao; Parikh, Atul

2015-11-18

We report a new and simple approach to prepare a class of silica-reinforced liposomes with hybrid core-shell nanostructures. The amphiphilic natural structure of lipids was exploited to sequester hydrophobic molecules, namely precursor TEOS and pyrene, in the hydrophobic midplane of liposomal bilayer assemblies in the aqueous phase. Subsequent interfacial hydrolysis of TEOS at the bilayer/water interface and ensuing condensation within the hydrophobic interstices of the lipid bilayer drives silica formation in situ, producing a novel class of silica-lipid hybrid liposils. Structural characterization by scanning- and transmission electron microscopy confirm that the liposils so generated preserve closed topologies and size-monodipersity of the parent lecithin liposomes, and DSC-TGA and XRD measurements provide evidence for the silica coating. Monitoring fluorescence measurements using embedded pyrene yield detailed information on microenvironment changes, which occur during sol-gel process and shed light on the structural evolution during silica formation. We envisage that liposils formed by this simple, new approach, exploiting the hydrophobic core of the lipid bilayer to spatially localize silica-forming precursors enables preparation of stable liposils exhibiting capacity for cargo encapsulation, bicompatibility, and fluorescence monitoring, more generally opening a window for construction of stable, functional hybrid materials.

Optical properties of zinc borotellurite glass doped with trivalent dysprosium ion

NASA Astrophysics Data System (ADS)

Ami Hazlin, M. N.; Halimah, M. K.; Muhammad, F. D.; Faznny, M. F.

2017-04-01

The zinc borotellurite doped with dysprosium oxide glass samples with chemical formula {[(TeO2) 0 . 7(B2O3) 0 . 3 ] 0 . 7(ZnO) 0 . 3 } 1 - x(Dy2O3)x (where x=0.01, 0.02, 0.03, 0.04 and 0.05 M fraction) were prepared by using conventional melt quenching technique. The structural and optical properties of the proposed glass systems were characterized by using X-ray diffraction (XRD) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and UV-VIS spectroscopy. The amorphous nature of the glass systems is confirmed by using XRD technique. The infrared spectra of the glass systems indicate three obvious absorption bands which are assigned to BO3 and TeO4 vibrational groups. Based on the absorption spectra obtained, the direct and indirect optical band gaps, as well as the Urbach energy were calculated. It is observed that both the direct and indirect optical band gaps increase with the concentration of Dy3+ ions. On the other hand, the Urbach energy is observed to decrease as the concentration of Dy3+ ions increases.

Electronic nose screening of ethanol release during sol-gel encapsulation. A novel non-invasive method to test silica polymerisation.

PubMed

Lovino, Magalí; Cardinal, M Fernanda; Zubiri, Diana B V; Bernik, Delia L

2005-12-15

Porous silica matrices prepared by sol-gel process yield biocompatible materials adequate for encapsulation of biomolecules or drugs. The procedure is simple and fast, but when alkoxyde precursors like tetraethoxysilane (TEOS) are used the polymerisation reaction leads to the formation of alcohol as a by-product, which can produce undesirable effects on the activity of entrapped enzymes or modify a drug release kinetic. Therefore, it is critical to determine that no remnant ethanol is left prior using or storing the obtained biomaterial. In this regard, the technique used in the alcohol determination should be non-invasive and non-destructive to preserve the encapsulation device intact and ready to use. In this work we have successfully used a portable electronic nose (e-nose) for the screening of silica polymerisation process during theophylline encapsulation. TEOS reaction was "smelt" since precursor pre-hydrolysis until the end of ethanol release, sensed directly at the headspace of matrices slabs. Measurements showed that ethanol was negligible since 10th day in polymeric slabs of 10 mm width and 2 cm diameter. This first use of e-nose following a polymerisation reaction opens a wide number of putative applications in pharmaceutical and biochemical fields.

A Bottle-around-a-Ship Method To Generate Hollow Thin-Shelled Particles Containing Encapsulated Iron Species with Application to the Environmental Decontamination of Chlorinated Compounds.

PubMed

Su, Yang; Wang, Yingqing; Owoseni, Olasehinde; Zhang, Yueheng; Gamliel, David Pierce; Valla, Julia A; McPherson, Gary L; John, Vijay T

2018-04-25

Thin-shelled hollow silica particles are synthesized using an aerosol-based process where the concentration of a silica precursor tetraethyl orthosilicate (TEOS) determines the shell thickness. The synthesis involves a novel concept of the salt bridging of an iron salt, FeCl 3 , to a cationic surfactant, cetyltrimethylammonium bromide (CTAB), which modulates the templating effect of the surfactant on silica porosity. The salt bridging leads to a sequestration of the surfactant in the interior of the droplet with the formation of a dense silica shell around the organic material. Subsequent calcination consistently results in hollow particles with encapsulated iron oxides. Control of the TEOS levels leads to the generation of ultrathin-shelled (∼10 nm) particles which become susceptible to rupture upon exposure to ultrasound. The dense silica shell that is formed is impervious to entry of chemical species. Mesoporosity is restored to the shell through desilication and reassembly, again using CTAB as a template. The mesoporous-shelled hollow particles show good reactivity toward the reductive dichlorination of trichloroethylene (TCE), indicating access of TCE to the particle interior. The ordered mesoporous thin-shelled particles containing active iron species are viable systems for chemical reaction and catalysis.

WE-D-BRB-03: Current State of Volumetric Image Guidance for Proton Therapy

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

Hua, C.

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. Itmore » introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy. B. Teo, B.K Teo had received travel funds from IBA in 2015.« less

WE-D-BRB-04: Clinical Applications of CBCT for Proton Therapy

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

Teo, B.

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. Itmore » introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy. B. Teo, B.K Teo had received travel funds from IBA in 2015.« less

WE-D-BRB-00: Basics of Proton Therapy

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

NONE

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. Itmore » introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy. B. Teo, B.K Teo had received travel funds from IBA in 2015.« less

WE-D-BRB-01: Basic Physics of Proton Therapy

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

Arjomandy, B.

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. Itmore » introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy. B. Teo, B.K Teo had received travel funds from IBA in 2015.« less

Waste form evaluation for RECl 3 and REO x fission products separated from used electrochemical salt

DOE PAGES

Riley, Brian J.; Pierce, David A.; Crum, Jarrod V.; ...

2017-09-22

The work presented here is based off the concept that the rare earth chloride (RECl 3) fission products within the used electrorefiner (ER) salt can be selectively removed as RECl 3 (not yet demonstrated) or precipitated out as a mixture of REOCl and REO x through oxygen sparging (has been demonstrated). This paper presents data showing the feasibility of immobilizing a mixture of RECl 3s at 10 mass% into a 78%TeO 2-22%PbO glass while also showing that this same mixture of RECl 3s can be oxidized to REOCl at 300 °C and then to REO x by 1200 °C, evolvingmore » Cl 2(g). When the REO x mixture is heated at temperatures >1200 °C, the ratios of REO xs change. The mixture of REO x was then immobilized in a lanthanide borosilicate (LABS) glass at a high loading of 60 mass%. Both the 78%TeO 2-22%PbO glass and LABS glass systems show good chemical durability. In conclusion, the advantages and disadvantages of tellurite and LABS glasses are compared.« less

Molecular characterization of vancomycin-resistant Enterococcus faecium isolates from Bermuda

PubMed Central

Akpaka, Patrick Eberechi; Kissoon, Shivnarine; Wilson, Clyde; Jayaratne, Padman; Smith, Ashley; Golding, George R.

2017-01-01

Molecular characteristics of vancomycin resistant enterococci isolates from Bermuda Island is currently unknown. This study was conducted to investigate phenotypic and genotypic characteristics of VRE isolates from Bermuda Island using the chromogenic agar, E-tests, polymerase chain reaction (PCR), pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Eighteen E. faecium isolates were completely analyzed and were all resistant to vancomycin, susceptible to linezolid and quinupristin/dalfopristin, positive for vanA and esp genes. The MLST analysis confirmed most isolates were of the sequence types linked to clonal complex 17 (CC17) that is widely associated with outbreaks in hospitals. Infection control measures, antibiotic stewardship, and surveillance activities will continue to be a priority in hospital on the Island. PMID:28267763

Molecular characterization of vancomycin-resistant Enterococcus faecium isolates from Bermuda.

PubMed

Akpaka, Patrick Eberechi; Kissoon, Shivnarine; Wilson, Clyde; Jayaratne, Padman; Smith, Ashley; Golding, George R

2017-01-01

Molecular characteristics of vancomycin resistant enterococci isolates from Bermuda Island is currently unknown. This study was conducted to investigate phenotypic and genotypic characteristics of VRE isolates from Bermuda Island using the chromogenic agar, E-tests, polymerase chain reaction (PCR), pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Eighteen E. faecium isolates were completely analyzed and were all resistant to vancomycin, susceptible to linezolid and quinupristin/dalfopristin, positive for vanA and esp genes. The MLST analysis confirmed most isolates were of the sequence types linked to clonal complex 17 (CC17) that is widely associated with outbreaks in hospitals. Infection control measures, antibiotic stewardship, and surveillance activities will continue to be a priority in hospital on the Island.

Operation HARDTACK. Volume 1. Radiological Safety

DTIC Science & Technology

1980-02-01

oo &ee Radex ISO teo ,70 VÄH0O EVKiT !60 HODOGRAPK RESULTANT WINDS AND SURFACE RADEX .-■"=0 2BO, 2cO 250 !OC...only reeordid .rsMiiig« vtrs ir-ade en Jpnet: 50 na/hri Ivcrne: B ax/ kc ; and n^ar th« gM-jcd ssrc at tven’^r-fivo feet) 1209 mr/fer» 4

The theory of expanded, extended, and enhanced opportunities for youth physical activity promotion.

PubMed

Beets, Michael W; Okely, Anthony; Weaver, R Glenn; Webster, Collin; Lubans, David; Brusseau, Tim; Carson, Russ; Cliff, Dylan P

2016-11-16

Physical activity interventions targeting children and adolescents (≤18 years) often focus on complex intra- and inter-personal behavioral constructs, social-ecological frameworks, or some combination of both. Recently published meta-analytical reviews and large-scale randomized controlled trials have demonstrated that these intervention approaches have largely produced minimal or no improvements in young people's physical activity levels. In this paper, we propose that the main reason for previous studies' limited effects is that fundamental mechanisms that lead to change in youth physical activity have often been overlooked or misunderstood. Evidence from observational and experimental studies is presented to support the development of a new theory positing that the primary mechanisms of change in many youth physical activity interventions are approaches that fall into one of the following three categories: (a) the expansion of opportunities for youth to be active by the inclusion of a new occasion to be active, (b) the extension of an existing physical activity opportunity by increasing the amount of time allocated for that opportunity, and/or (c) the enhancement of existing physical activity opportunities through strategies designed to increase physical activity above routine practice. Their application and considerations for intervention design and interpretation are presented. The utility of these mechanisms, referred to as the Theory of Expanded, Extended, and Enhanced Opportunities (TEO), is demonstrated in their parsimony, logical appeal, support with empirical evidence, and the direct and immediate application to numerous settings and contexts. The TEO offers a new way to understand youth physical activity behaviors and provides a common taxonomy by which interventionists can identify appropriate targets for interventions across different settings and contexts. We believe the formalization of the TEO concepts will propel them to the forefront in the

Double-Layer Surface Modification of Polyamide Denture Base Material by Functionalized Sol-Gel Based Silica for Adhesion Improvement.

PubMed

Hafezeqoran, Ali; Koodaryan, Roodabeh

2017-09-21

Limited surface treatments have been proposed to improve the bond strength between autopolymerizing resin and polyamide denture base materials. Still, the bond strength of autopolymerizing resins to nylon polymer is not strong enough to repair the fractured denture effectively. This study aimed to introduce a novel method to improve the adhesion of autopolymerizing resin to polyamide polymer by a double layer deposition of sol-gel silica and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (AE-APTMS). The silica sol was synthesized by acid-catalyzed hydrolysis of tetraethylorthosilicate (TEOS) as silica precursors. Polyamide specimens were dipped in TEOS-derived sol (TS group, n = 28), and exposed to ultraviolet (UV) light under O 2 flow for 30 minutes. UV-treated specimens were immersed in AE-APTMS solution and left for 24 hours at room temperature. The other specimens were either immersed in AE-APTMS solution (AP group, n = 28) or left untreated (NT group, n = 28). Surface characterization was investigated by fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). Two autopolymerizing resins (subgroups G and T, n = 14) were bonded to the specimens, thermocycled, and then tested for shear bond strength with a universal testing machine. Data were analyzed with one-way ANOVA followed by Tukey's HSD (α = 0.05). FTIR spectra of treated surfaces confirmed the chemical modification and appearance of functional groups on the polymer. One-way ANOVA revealed significant differences in shear bond strength among the study groups. Tukey's HSD showed that TS T and TS G groups had significantly higher shear bond strength than control groups (p = 0.001 and p < 0.001, respectively). Moreover, bond strength values of AP T were statistically significant compared to controls (p = 0.017). Amino functionalized TEOS-derived silica coating is a simple and cost-effective method for improving the bond strength between the autopolymerizing resin and polyamide

A Very Compact, High Speed and Rugged Acousto-Optic Tunable Filter for Wavelength Division Demultiplexing in Fiber Optic Communication Networks. Phase 1

DTIC Science & Technology

1995-06-30

Novel concepts of near-collinear/collinear acousto - optic interactions have been investigated during this SBIR Phase I program. As a result, several...new acousto - optic tunable filters have been built and tested. The program is highlighted by: (1) Design, fabrication and experimental demonstration of...a novel TeO2 near-collinear acousto - optic tunable filter has been designed, fabricated and tested. The device exhibits a 1.29 nm spectral resolution

Misrecognition and science education reform

NASA Astrophysics Data System (ADS)

Brandt, Carol B.

2012-09-01

In this forum, I expand upon Teo and Osborne's discussion of teacher agency and curriculum reform. I take up and build upon their analysis to further examine one teacher's frustration in enacting an inquiry-based curriculum and his resulting accommodation of an AP curriculum. In this way I introduce the concept of misrecognition (Bourdieu and Passeron 1977) to open up new ways of thinking about science inquiry and school reform.

Experimental and Computational Characterization of Combustion Phenomena

DTIC Science & Technology

2006-05-01

combustors without installing glass , quartz, or sapphire windows when using terahertz radiation. To explore the potential diagnostics utility of T...laser was reduced using a Spectra-Physics Model 3980 pulse selector. This device employs a TeO2 acousto-optic modulator to select subsets of pulses...equipped with a UG-11 and two WG-295 colored glass filters to reduce visible and laser-scattered light, respectively. OH-PLIF images were acquired

Amorphous Fast Ion Conducting Systems, Part 1. Structure and Properties of Mid and Far IR Transmitting Materials, Part 2

DTIC Science & Technology

1991-10-31

Glasses with high conductivities can also be formed with the Lewis acids GeO 2 (11 ) and no doubt Bi 20 3, TeO2 , etc., but these have been less...P age 3 1. Mechanical Relaxation and Relation to Electrical Relaxation in Fast Ion-Conducting Glasses ...relaxation although considerable information was available for the classical alkali silicate and borate glasses . Our program was to utilize the rheovibron

A Program for Developing Automated Scientific-Information Processing in Maritime Economy,

DTIC Science & Technology

1983-11-17

leat triple. The- exchange of tapes is n bviusocorrase. or. 0* 0 for the fishing brancft within the framework of a ftfw.Pltat ffkflng Agaemt(materials...from ZSR DnOOR Of Sooialist bep *46es3 a" MIS. T"e sept l oeeItu’e usmm we4 tta tft rpaxisatica of the first sta In the SUS40t or s4100irse.. ’teo~oal

Comparison of PCR/Electron spray Ionization-Time-of-Flight-Mass Spectrometry versus Traditional Clinical Microbiology for active surveillance of organisms contaminating high-use surfaces in a burn intensive care unit, an orthopedic ward and healthcare workers

PubMed Central

2012-01-01

Background Understanding nosocomial pathogen transmission is restricted by culture limitations. Novel platforms, such as PCR-based electron spray ionization-time-of-flight-mass spectrometry (ESI-TOF-MS), may be useful as investigational tools. Methods Traditional clinical microbiology (TCM) and PCR/ESI-TOF-MS were used to recover and detect microorganisms from the hands and personal protective equipment of 10 burn intensive care unit (ICU) healthcare workers providing clinical care at a tertiary care military referral hospital. High-use environmental surfaces were assessed in 9 burn ICU and 10 orthopedic patient rooms. Clinical cultures during the study period were reviewed for pathogen comparison with investigational molecular diagnostic methods. Results From 158 samples, 142 organisms were identified by TCM and 718 by PCR/ESI-TOF-MS. The molecular diagnostic method detected more organisms (4.5 ± 2.1 vs. 0.9 ± 0.8, p < 0.01) from 99% vs. 67% of samples (p < 0.01). TCM detected S. aureus in 13 samples vs. 21 by PCR/ESI-TOF-MS. Gram-negative organisms were less commonly identified than gram-positive by both methods; especially by TCM. Among all detected bacterial species, similar percentages were typical nosocomial pathogens (18-19%) for TCM vs. PCR/ESI-TOF-MS. PCR/ESI-TOF-MS also detected mecA in 112 samples, vanA in 13, and KPC-3 in 2. MecA was associated (p < 0.01) with codetection of coagulase negative staphylococci but not S. aureus. No vanA was codetected with enterococci; one KPC-3 was detected without Klebsiella spp. Conclusions In this pilot study, PCR/ESI-TOF-MS detected more organisms, especially gram-negatives, compared to TCM, but the current assay format is limited by the number of antibiotic resistance determinants it covers. Further large-scale assessments of PCR/ESI-TOF-MS for hospital surveillance are warranted. PMID:23050585

Co-concentration effect of silane with natural extract on biodegradable polymeric films for food packaging.

PubMed

Bashir, Anbreen; Jabeen, Sehrish; Gull, Nafisa; Islam, Atif; Sultan, Misbah; Ghaffar, Abdul; Khan, Shahzad Maqsood; Iqbal, Sadia Sagar; Jamil, Tahir

2018-01-01

Novel biodegradable films were prepared by blending guar gum, chitosan and poly (vinyl alcohol) having mint (ME) and grapefruit peel (GE) extracts and crosslinked with nontoxic tetraethoxysilane (TEOS). The co-concentration effect of TEOS with natural extracts on the films was studied. FTIR analysis confirmed the presence of incorporated components and the developed interactions among the polymer chains. The surface morphology of the films by SEM showed the hydrophilic character due to porous network structure. The films having both ME and GE with maximum amount of crosslinker (100μL), showed maximum swelling (58g/g) and stability while the optical properties showed increased protection against UV light. This film sample showed compact network structure which enhanced the ultimate tensile strength (40.03MPa) and elongation at break (104.8%). ME/GE conferred the antioxidant properties determined by radical scavenging activity and total phenolic contents (TPC) as ME films have greater TPC compared to GE films. The soil burial test exhibited the degradation of films rapidly (6days) confirming their strong microbial activity in soil. The lower water vapour transmission rate and water vapour permeability showed better shelf life; hence, these biodegradable films are environmental friendly and have potential for food and other packaging. Copyright © 2017 Elsevier B.V. All rights reserved.

CUORE: The Three Towers Test

NASA Astrophysics Data System (ADS)

Goodsell, Alison; Sparks, Laura

2008-10-01

CUORE (Cryogenic Underground Observatory for Rare Events) will be part of the next generation of detectors used to search for neutrinoless double beta decay (0νββ). Located in Assergi, Italy at the Gran Sasso National Laboratory (LNGS), CUORE will be a large cryogenic bolometer composed of 988 tellurium dioxide (TeO2) detectors with a total mass of 750 kg, and will search for 0νββ in ^130Te. The intermediate upgrade, CUORE-0, first involves the disassembly of Cuoricino, CUORE's smaller counterpart in operation since 2003, and the readying of the Three Towers test, a diagnostic detector configuration. As the experiment will monitor the extremely rare event of 0νββ, all factors contributing to background need to be minimized to effectively increase the sensitivity. We assisted the LNGS researchers over the summer of 2008 by supporting R&D work with the Three Towers test to reduce the radioactive background of the experiment. Activities involved decontaminating the copper frame of radon daughters, and chemically etching and lapping the TeO2 crystals with nitric acid and silicon dioxide, respectively, to remove surface contaminants which contribute to background counts. This work was supported in part by NSF grant PHY- 0653284 and the California State Faculty Support Grant.

Polychlorinated dibenzo-p-dioxins and dibenzofurans in the atmosphere around the Great Lakes.

PubMed

Venier, Marta; Ferrario, Joseph; Hites, Ronald A

2009-02-15

The atmospheric concentrations of PCDDs and PCDFs were measured in four sites near the shores of the North American Great Lakes. The sites included an urban site (Chicago, Illinois) and three rural/remote sites (Eagle Harbor, Michigan; Sleeping Bear Dunes, Michigan; and Sturgeon Point, New York). Sampling occurred every 24 days between November 2004 and December 2007. The concentration of PCDD/Fs averaged 2.3 +/- 0.2 fg WHO TEQ/m3 at Eagle Harbor, 35 +/- 3 fg WHO TEO/ m3 at Chicago, 7.4 +/- 1.4 fg WHO TEO/m3 at Sleeping Bear Dunes, and 13 +/- 2 fg WHO TED/m3 at Sturgeon Point. The total concentration of the 17 toxic PCDD/F congeners showed a significant seasonal trend at all sites, except Chicago. The date of maximum concentration averaged Dec 6 +/- 35 days, which is consistent with residential heating being an important source of PCDD/Fs to the atmosphere. A significant positive relationship between the logarithm of the total concentration of the 17 toxic PCDD/F congeners and the logarithm of the number of people within a 25 km radius around the sampling site was found. We suggest that urban and industrial areas, which are heavily populated, act as sources of PCDDs and PCDFs to the atmosphere.

Bacterial recovery and recycling of tellurium from tellurium-containing compounds by Pseudoalteromonas sp. EPR3.

PubMed

Bonificio, W D; Clarke, D R

2014-11-01

Tellurium-based devices, such as photovoltaic (PV) modules and thermoelectric generators, are expected to play an increasing role in renewable energy technologies. Tellurium, however, is one of the scarcest elements in the earth's crust, and current production and recycling methods are inefficient and use toxic chemicals. This study demonstrates an alternative, bacterially mediated tellurium recovery process. We show that the hydrothermal vent microbe Pseudoalteromonas sp. strain EPR3 can convert tellurium from a wide variety of compounds, industrial sources and devices into metallic tellurium and a gaseous tellurium species. These compounds include metallic tellurium (Te(0)), tellurite (TeO3(2-)), copper autoclave slime, tellurium dioxide (TeO2), tellurium-based PV material (cadmium telluride, CdTe) and tellurium-based thermoelectric material (bismuth telluride, Bi2Te3). Experimentally, this was achieved by incubating these tellurium sources with the EPR3 in both solid and liquid media. Despite the fact that many of these tellurium compounds are considered insoluble in aqueous solution, they can nonetheless be transformed by EPR3, suggesting the existence of a steady state soluble tellurium concentration during tellurium transformation. These experiments provide insights into the processes of tellurium precipitation and volatilization by bacteria, and their implications on tellurium production and recycling. © 2014 The Society for Applied Microbiology.

Fast nucleation for silica nanoparticle synthesis using a sol-gel method.

PubMed

Dixit, Chandra K; Bhakta, Snehasis; Kumar, Ajeet; Suib, Steven L; Rusling, James F

2016-12-01

We have developed a method that for the first time allowed us to synthesize silica particles in 20 minutes using a sol-gel preparation. Therefore, it is critically important to understand the synthesis mechanism and kinetic behavior in order to achieve a higher degree of fine tuning ability during the synthesis. In this study, we have employed our ability to modulate the physical nature of the reaction medium from sol-gel to emulsion, which has allowed us to halt the reaction at a particular time; this has allowed us to precisely understand the mechanism and chemistry of the silica polymerization. The synthesis medium is kept quite simple with tetraethyl orthosilicate (TEOS) as a precursor in an equi-volumetric ethanol-water system and with sodium hydroxide as a catalyst. Synthesis is performed under ambient conditions at 20 °C for 20 minutes followed by phasing out of any unreacted TEOS and polysilicic acid chains via their emulsification with supersaturated water. We have also demonstrated that the developed particles with various sizes can be used as seeds for further particle growth and other applications. Luminol, a chemiluminescent molecule, has been entrapped successfully between the layers of silica and was demonstrated for the chemiluminescence of these particles.

Temperature relations and abundance determinations in H II regions

NASA Astrophysics Data System (ADS)

Arellano-Córdova, K. Z.; Rodríguez, M.; Delgado-Inglada, G.

2017-11-01

Most abundance determinations in H II regions, especially for extragalactic regions, are based on the use of temperature relations, usually between Te[N II] and Te[O III]. The calibration of strong-line methods also generally rely on the use of these relations. We explore here the reliability of old and new Te[N II]-Te[O III] relations, their dispersions, and their effects on the calculation of chemical abundances. In order to do so, we have compiled and analyzed in a homogeneous way a sample of 155 H II regions that have measurements of both temperatures. We find that some of the largest departures from the temperature relation are probably due to shocks affecting Te[N II]. We consider the effects of recombination in Te[N II] and of line blending in Te[O III], and find a residual dependence of the temperature relation on the degree of ionization. We provide new robust fits of the relation and show that our fits lead to better abundance determinations. Our fits are very similar to the most used temperature relation, based on a grid of photoionization models by Stasińska (1982), and variously cited as Campbell et al. (1986) or Garnett (1992).

Compilation of reinforced carbon-carbon transatlantic abort landing arc jet test results

NASA Technical Reports Server (NTRS)

Milhoan, James D.; Pham, Vuong T.; Yuen, Eric H.

1993-01-01

This document consists of the entire test database generated to support the Reinforced Carbon-Carbon Transatlantic Abort Landing Study. RCC components used for orbiter nose cap and wing leading edge thermal protection were originally designed to have a multi-mission entry capability of 2800 F. Increased orbiter range capability required a predicted increase in excess of 3300 F. Three test series were conducted. Test series #1 used ENKA-based RCC specimens coated with silicon carbide, treated with tetraethyl orthosilicate, sealed with Type A surface enhancement, and tested at 3000-3400 F with surface pressure of 60-101 psf. Series #2 used ENKA- or AVTEX-based RCC, with and without silicon carbide, Type A or double Type AA surface enhancement, all impregnated with TEOS, and at temperatures from 1440-3350 F with pressures from 100-350 psf. Series #3 tested ENKA-based RCC, with and without silicon carbide coating. No specimens were treated with TEOS or sealed with Type A. Surface temperatures ranged from 2690-3440 F and pressures ranged from 313-400 psf. These combined test results provided the database for establishing RCC material single-mission-limit temperature and developing surface recession correlations used to predict mass loss for abort conditions.

In silico modeling and experimental evidence of coagulant protein interaction with precursors for nanoparticle functionalization.

PubMed

Okoli, Chuka; Sengottaiyan, Selvaraj; Arul Murugan, N; Pavankumar, Asalapuram R; Agren, Hans; Kuttuva Rajarao, Gunaratna

2013-10-01

The design of novel protein-nanoparticle hybrid systems has applications in many fields of science ranging from biomedicine, catalysis, water treatment, etc. The main barrier in devising such tool is lack of adequate information or poor understanding of protein-ligand chemistry. Here, we establish a new strategy based on computational modeling for protein and precursor linkers that can decorate the nanoparticles. Moringa oleifera (MO2.1) seed protein that has coagulation and antimicrobial properties was used. Superparamagnetic nanoparticles (SPION) with precursor ligands were used for the protein-ligand interaction studies. The molecular docking studies reveal that there are two binding sites, one is located at the core binding site; tetraethoxysilane (TEOS) or 3-aminopropyl trimethoxysilane (APTES) binds to this site while the other one is located at the side chain residues where trisodium citrate (TSC) or Si60 binds to this site. The protein-ligand distance profile analysis explains the differences in functional activity of the decorated SPION. Experimentally, TSC-coated nanoparticles showed higher coagulation activity as compared to TEOS- and APTES-coated SPION. To our knowledge, this is the first report on in vitro experimental data, which endorses the computational modeling studies as a powerful tool to design novel precursors for functionalization of nanomaterials; and develop interface hybrid systems for various applications.

Low-temperature high-Z gamma-detectors with very high energy resolution

NASA Astrophysics Data System (ADS)

Pobes, Carlos; Brofferio, Chiara; Bucci, Carlo; Cremonesi, Oliviero; Fiorini, Ettore; Giuliani, Andrea; Nucciotti, Angelo; Pavan, Maura; Pedretti, Marisa; Pessina, Gianluigi; Pirro, Stefano; Previtali, Ezio; Sisti, Monica; Vanzini, Marco; Zanotti, Luigi

2001-12-01

High-Z low-temperature calorimeters are developed by an Italian collaboration (Milano-Como-Gran Sasso Underground Laboratories) in order to search for rare nuclear events and Dark Matter massive candidates. They exhibit an excellent energy resolution, close to that of Ge-diodes, but a much higher efficiency. Different high-Z materials were initially employed . A many-years optimisation work on tellurium oxide (TeO2) lead to impressive results: devices with total masses around 750 g present FWHM energy resolutions on gamma-ray peaks ranging from 1 KeV (close to the 5 KeV energy threshold) to 2.6 KeV at 2615 KeV (208Tl gamma line). A 3.2 KeV FWHM energy resolution was obtained at 5.4 MeV (210Po alpha line), which is by far the best one ever achieved with any alpha detector. These devices, operated at about 10 mK, consist of a TeO2 single crystal thermally coupled to a 50 mg Neutron Transmutation Doped (NTD) Ge crystal working as a temperature sensor. Special care was devoted to methods for response linearization and temporal stabilisation. Devices based on the same principle and specifically optimised could find applications in several fields like gamma-ray astrophysics, nuclear physics searches, environmental monitoring and radiation metrology.

A WLED based on LuAG:Ce3+ PiG coated red-emitting K2SiF6:Mn4+ phosphor by screen-printing

NASA Astrophysics Data System (ADS)

Cao, Rui; Wu, Lingchao; Di, Xiaoxuan; Li, Pengzhi; Hu, Guangcai; Liang, Xiaojuan; Xiang, Weidong

2017-08-01

It is high-profile that the use of phosphor-in-glass (PiG) is extensive because of its excellent advantages in thermal resistance and lifetime aspects, and so on. Here, white light-emitting diodes (WLED) based on LuAG:Ce3+ PiG coated red-emitting K2SiF6:Mn4+ (KSF) phosphors by screen-printing are fabricated. Among all of these, the commercial LuAG phosphors and glass raw materials of TeO2-based glass, were weighted and milled in an agate thoroughly. Then, the mixture was melted and sintered at 850 K or so for 20 min in the ambient atmosphere through low temperature co-fired method, cold-forming LuAG PiG clump and cut into different LuAG PiG thicknesses. After that, the commercial red phosphor KSF was coated on LuAG PiG by screen-printing technique. Finally, high-performance WLEDs based on the TeO2-based glass were obtained, tested and characterized, which exhibit a highest color rendering index of 94.1, a lowest color temperature of 3744 K and a largest luminous efficiency of 101.02 lm·W-1. Most noticeably of all, the promising method has excellent developing potential for industrialization in high-power WLED.

All-solid tellurite optical fiber with transversely disordered refractive index profile and its optical image transport performance

NASA Astrophysics Data System (ADS)

Tong, Hoang Tuan; Kuroyanagi, Shunei; Suzuki, Takenobu; Ohishi, Yasutake

2018-02-01

All-solid tellurite-glass optical rod and fiber with transversely-disordered refractive index profile were successfully fabricated to study the transport of infrared images by using transverse localization of light. The fabrication was carried out by using stack-and-draw and rod-in-tube techniques. The fabricated tellurite optical rod and fiber were composed of high-index and low-index units which were arranged randomly in the transverse plane but were invariant in the longitudinal direction. The diameter of each unit was approximately 1.0 μm. The high-index and low-index materials were TeO2-Li2O-WO3-MoO3-Nb2O5 (TLWMN) glass and TeO2-ZnO-Na2O-La2O3 (TZNL) glass, respectively. At 1550 nm, their refractive index difference Δn is 0.096. To investigate the optical image transport capability, A CW laser light at 1550 nm was used as an input probe beam and the 1951 U.S. Air Force test target was installed in front of 10-cm-long segments of the fabricated rod and fiber in the experimental setup. The output signal was recorded by a beam profiler. As a result, clear transported images of numbers and lines on the test target were obtained.

Structure, glass transition temperature and spectroscopic properties of 10Li2O-xP2O5-(89-x)TeO2-1CuO (5≤x≤25 mol%) glass system.

PubMed

Upender, G; Babu, J Chinna; Mouli, V Chandra

2012-04-01

X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectrometry (EDS), differential scanning calorimetry (DSC), infrared (IR), Raman, electron paramagnetic resonance (EPR) and optical absorption studies on 10Li2O-xP2O5-(89-x)TeO2-1CuO glasses (where x=5, 10, 15, 20 and 25 mol%) have been carried out. The amorphous nature of the glasses was confirmed using XRD and FESEM measurements. The glass transition temperature (Tg) of glass samples have been estimated from DSC traces and found that the Tg increases with increasing P2O5 content. Both the IR and Raman studies have been showed that the present glass system consists of [TeO3], [TeO4], [PO3] and [PO4] units. The spin-Hamiltonian parameters such as g∥, g⊥, and A∥ have been determined from EPR spectra and it was found that the Cu2+ ion is present in tetragonal distorted octahedral site with [Formula: see text] as the ground state. Bonding parameters and bonding symmetry of Cu2+ ions have been calculated by correlating EPR and optical data and were found to be composition dependent. Copyright © 2012 Elsevier B.V. All rights reserved.

Glass formation and structure of calcium antimony phosphate glasses and those doped with tellurium oxide

NASA Astrophysics Data System (ADS)

Li, Jun; Zhang, Yin; Nian, Shangjiu; Wu, Zhenning; Cao, Weijing; Zhou, Nianying; Wang, Danian

2017-03-01

An approximate glass-forming region in the P2O5-Sb2O3-CaO ternary system was determined. The properties and structure of two compositional series of (A) (75- x)P2O5- xSb2O3-25CaO ( x = 20, 25, 30, 35 mol%) and (B) 45P2O5-30Sb2O3-(25- x)CaO- xTeO2 ( x = 5, 10, 15, 20 mol%) were studied systematically. Thermal properties were investigated by means of differential scanning calorimetry (DSC). The densities of all samples were measured by Archimedes' method using distilled water as the immersion liquid. The water durability of the glasses was described by their dissolution rate (DR) in the distilled water at 90 °C for some time periods. Density, thermal stability and water durability were improved with the addition of Sb2O3 and TeO2. Structural studies were carried out by X-ray diffraction (XRD), infrared spectroscopy and Raman spectroscopy. The phosphate chain depolymerization occurred with the increase of Sb2O3 and the Q2 structural units transformed to the Q1 and Q0 structural units with the addition of TeO2.

Solution-derived SiO2 gate insulator formed by CO2 laser annealing for polycrystalline silicon thin-film transistors

NASA Astrophysics Data System (ADS)

Hishitani, Daisuke; Horita, Masahiro; Ishikawa, Yasuaki; Ikenoue, Hiroshi; Uraoka, Yukiharu

2017-05-01

The formation of perhydropolysilazane (PHPS)-based SiO2 films by CO2 laser annealing is proposed. Irradiation with a CO2 laser with optimum fluence transformed a prebaked PHPS film into a SiO2 film with uniform composition in the thickness direction. Polycrystalline silicon thin-film transistors (poly-Si TFTs) with a SiO2 film as the gate insulator were fabricated. When the SiO2 film was formed by CO2 laser annealing (CO2LA) at the optimum fluence of 20 mJ/cm2, the film had fewer OH groups which was one-twentieth that of the furnace annealed PHPS film and one-hundredth that of the SiO2 film deposited by plasma-enhanced chemical vapor deposition (PECVD) using tetraethyl orthosilicate (TEOS). The resulting TFTs using PHPS showed a clear transistor operation with a field-effect mobility of 37.9 ± 1.2 cm2 V-1 s-1, a threshold voltage of 9.8 ± 0.2 V, and a subthreshold swing of 0.76 ± 0.02 V/decade. The characteristics of such TFTs were as good as those of a poly-Si TFT with a SiO2 gate insulator prepared by PECVD using TEOS.

Detection of Clinical Depression in Adolescents’ Speech During Family Interactions

PubMed Central

Low, Lu-Shih Alex; Maddage, Namunu C.; Lech, Margaret; Sheeber, Lisa B.; Allen, Nicholas B.

2013-01-01

The properties of acoustic speech have previously been investigated as possible cues for depression in adults. However, these studies were restricted to small populations of patients and the speech recordings were made during patients’ clinical interviews or fixed-text reading sessions. Symptoms of depression often first appear during adolescence at a time when the voice is changing, in both males and females, suggesting that specific studies of these phenomena in adolescent populations are warranted. This study investigated acoustic correlates of depression in a large sample of 139 adolescents (68 clinically depressed and 71 controls). Speech recordings were made during naturalistic interactions between adolescents and their parents. Prosodic, cepstral, spectral, and glottal features, as well as features derived from the Teager energy operator (TEO), were tested within a binary classification framework. Strong gender differences in classification accuracy were observed. The TEO-based features clearly outperformed all other features and feature combinations, providing classification accuracy ranging between 81%–87% for males and 72%–79% for females. Close, but slightly less accurate, results were obtained by combining glottal features with prosodic and spectral features (67%–69% for males and 70%–75% for females). These findings indicate the importance of nonlinear mechanisms associated with the glottal flow formation as cues for clinical depression. PMID:21075715

Synthesis and structure of pyridine-functionalized mesoporous SBA-15 organosilicas and their application for sorption of diclofenac

NASA Astrophysics Data System (ADS)

Barczak, Mariusz

2018-02-01

A series of pyridine-functionalized mesoporous silicas have been prepared for the first time via direct co-condensation of tetraethoxysilane (TEOS) and 2-(2-pyridyl)ethyltrimethoxysilane (PETS) using the block copolymer Pluronic P123 as a structure-directing agent. The obtained materials were fully characterized by a wide range of instrumental techniques and employed as adsorbents for the removal of a diclofenac which is considered a priority hazardous drug. The synthesized materials exhibit a high adsorption capacities and rapid adsorption rates. The structural and adsorption properties depend largely on the relative amount of PETS/TEOS ratio: the gradual degradation of ordered structure and porosity was observed with the increasing amount of PETS. However due to the highest loading of pyridine units the most structurally degraded material had the highest adsorption uptake (631 mg g-1) indicating that the surface chemistry plays - along with porosity - an important role in governing the adsorption process. The experimental adsorption data were modelled using the Langmuir, Freundlich and Langmuir-Freundlich isotherms - among them the Langmuir-Freundlich model turned out to be the most suitable for describing adsorption behaviour of diclofenac onto the materials. The collected data show that the pyridine-functionalized mesoporous silicas can be a promising absorbent of pharmaceuticals.

Inorganic/Organic Hybrid Silica Nanoparticles as a Nitric Oxide Delivery Scaffold.

PubMed

Shin, Jae Ho; Schoenfisch, Mark H

2008-01-01

The preparation and characterization of nitric oxide (NO)-releasing silica particles formed following the synthesis of N -diazeniumdiolate-modified aminoalkoxysilanes are reported. Briefly, an aminoalkoxysilane solution was prepared by dissolving an appropriate amount of aminoalkoxysilane in a mixture of ethanol, methanol, and sodium methoxide (NaOMe) base. The silane solution was reacted with NO (5 atm) to form N -diazeniumdiolate NO donor moieties on the amino-alkoxysilanes. Tetraethoxy- or tetramethoxysilane (TEOS or TMOS) was then mixed with different ratios of N -diazeniumdiolate-modified aminoalkoxysilane (10 - 75 mol%, balance TEOS or TMOS). Finally, the silane mixture was added into ethanol in the presence of an ammonia catalyst to form NO donor silica nanoparticles via a sol-gel process. This synthetic approach allows for the preparation of NO delivery silica scaffolds with remarkably improved NO storage and release properties, surpassing all macromolecular NO donor systems reported to date with respect to NO payload (11.26μmol·mg -1 ), maximum NO release amount (357000 ppb·mg -1 ), NO release half-life (253 min), and NO release duration (101 h). The N -diazeniumdiolate-modified silane monomers and the resulting silica nanoparticles were characterized by 29 Si nuclear magnetic resonance (NMR) spectroscopy, UV-visible spectroscopy, chemiluminescence, atomic force microscopy (AFM), gas adsorption-desorption isotherms, and elemental analysis.

Sol/Gel Processing Techniques for Glass Matrix Composites.

DTIC Science & Technology

1987-11-01

silica alkoxide gels were also produced by an initial partial hydrolysis of TEOS. ,. After an aging period of 18-24 hrs. titanium (IV) isopropoxide ...preparation of these materials is the large difference in hydrolysis rate for titanium versus silica alkoxides. Thus, the tendency towards phase separation in...ethanol solution (Ref. 6-9). After an aging time, the more reactive titanium alkoxide is added. This solution gels quickly and is ready to be further

Development of a High Efficiency Q-Switched Glass Laser via Sol-Gel Processing

DTIC Science & Technology

1989-10-30

APPENDICES I. A. Aluminum as the "Buffer" Component B. Phosphorous as the "Buffer" Component Titanium as the "Buffer" Component II. Characteristics of Nd...alternative dehydrating agents, but with similar, undesirable results. Gels containing aluminum, phosphorus, or titanium as a third component all reacted...with aluminum isopropoxide and TEOS resulted in 50 A pore radii after drying, and densified without foaming to produce a clear, monolithic glass [22

CRREL (Cold Regions Research and Engineering Laboratory) Technical Publications. Supplement

DTIC Science & Technology

1986-09-01

Utilization for Fresh Water Production, ROAD. CHIMCAL COMPOSITION OF DUST nical memorandum~ Mar. 1976, No. 116, Muske Re- Weather Modilicationt, and...it appeared in a J-9 core Commes a i elon teo kEvromna 516 on an unusual boundary layer showing in th core andaa PV.e sEvromns assessment of the...SEA ICE IN at lowbtrquencinsfroad nttrsnsmtterseadofthelnductive 37.4035 THE 50-15 MHZ RANGEL coupling between two loop ntennaus are describsed

Survey of Hyperspectral and Multispectral Imaging Technologies (Etude sur les technologies d’imagerie hyperspectrale et multispectrale)

DTIC Science & Technology

2007-05-01

but relatively low acoustic figure of merit (the ability to couple acoustic wave to the crystal). In the infrared region TeO2 crystal (0.35 – 5.0 µm...filter. More in particular, it is based on a Lyot filter, which is a sandwich of birefringent liquid crystal, glass , quartz placed between two...variable retardance element in the sandwich composed of quartz, glass , polarizers and liquid crystal itself. To achieve the desired wavelength

High-Purity Glasses Based on Arsenic Chalcogenides

DTIC Science & Technology

2001-06-01

Chemical interaction of chalcogenides and some impurities (CS 2, TeO2 ) with the quartz glass at high temperature leads to the thin layers formation...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO1 1523 TITLE: High-Purity Glasses Based on Arsenic Chalcogenides...Materials Vol. 3, No. 2, June 2001, p. 341 - 349 HIGH-PURITY GLASSES BASED ON ARSENIC CHALCOGENIDES M. F. Churbanov, I. V. Scripachev, G. E. Snopatin, V. S

A Review of Positive Ion Sensitivities for the SIMS Analysis of CMT

DTIC Science & Technology

1991-05-01

microprobe. Inter-laboratory exercises organised by NRL using standardised glasses and steels’ s showed considerable agreement usually within a factor...would be sufficient oxygen to convert all the remaining matrix atoms to oxides, TeO2 and CdO. Any general theory of the lonisation of sputtered particles...Eggert equation which works well for many other matrices, such as metals, glasses and ceramics. Despite decades of basic studies there is still no

Elaboration and optimization of tellurite-based materials for raman gain application

NASA Astrophysics Data System (ADS)

Guery, Guillaume

Tellurite-based oxide glasses have been investigated as promising materials for Raman gain applications, due to their good linear and nonlinear optical properties and their wide transparency windows in the near- and midwave infrared spectral region. Furthermore, their interesting thermal properties, i.e. low glass transition temperature and ability to be drawn into optical fibers, make tellurite-based glasses excellent candidates for optical fiber amplifiers. The estimation of the strength and spectral distribution of Raman gain in materials is commonly approximated from the spontaneous Raman scattering cross-section measurement. For development of tellurite-based glasses as Raman amplifiers, understanding the relationship between glass structure, vibrational response, and nonlinear optical properties (NLO) represents a key point. This dissertation provides an answer to the fundamental question of the PhD study: "What is the impact of the glass structure on Raman gain properties of tellurite glasses?" This dissertation summarizes findings on different tellurite-based glass families: the TeO2-TaO5/2-ZnO, TeO2-BiO 3/2-ZnO and TeO2-NbO5/2 glass networks. The influence of glass modifiers has been shown on the glass' properties. Introduction of tantalum oxide or zinc oxide has been shown to increase the glass' stability against crystallization, quantified by DeltaT, where DeltaT = Tx -Tg. Added to the variation of the glass viscosity, this attribute is critical in fabricating optical fibers and for the use of these materials in fiber-based Raman gain applications. The role of ZnO in the tellurite network and the mechanism for structural modification has been determined. This addition results in not only the largest DeltaT reported for these highly nonlinear glasses to date, but coincides with a commensurate decrease of the refractive index. A hydroxyl purification has been developed that when employed, resulted in high purity preform materials exhibiting a limited

Facile large-scale synthesis of brain-like mesoporous silica nanocomposites via a selective etching process

NASA Astrophysics Data System (ADS)

Chen, Yu; Wang, Qihua; Wang, Tingmei

2015-10-01

The core-shell structured mesoporous silica nanomaterials (MSNs) are experiencing rapid development in many applications such as heterogeneous catalysis, bio-imaging and drug delivery wherein a large pore volume is desirable. We develop a one-pot method for large-scale synthesis of brain-like mesoporous silica nanocomposites based on the reasonable change of the intrinsic nature of the -Si-O-Si- framework of silica nanoparticles together with a selective etching strategy. The as-synthesized products show good monodispersion and a large pore volume of 1.0 cm3 g-1. The novelty of this approach lies in the use of an inorganic-organic hybrid layer to assist the creation of large-pore morphology on the outermost shell thereby promoting efficient mass transfer or storage. Importantly, the method is reliable and grams of products can be easily prepared. The morphology on the outermost silica shell can be controlled by simply adjusting the VTES-to-TEOS molar ratio (VTES: triethoxyvinylsilane, TEOS: tetraethyl orthosilicate) as well as the etching time. The as-synthesized products exhibit fluorescence performance by incorporating rhodamine B isothiocyanate (RITC) covalently into the inner silica walls, which provide potential application in bioimaging. We also demonstrate the applications of as-synthesized large-pore structured nanocomposites in drug delivery systems and stimuli-responsive nanoreactors for heterogeneous catalysis.The core-shell structured mesoporous silica nanomaterials (MSNs) are experiencing rapid development in many applications such as heterogeneous catalysis, bio-imaging and drug delivery wherein a large pore volume is desirable. We develop a one-pot method for large-scale synthesis of brain-like mesoporous silica nanocomposites based on the reasonable change of the intrinsic nature of the -Si-O-Si- framework of silica nanoparticles together with a selective etching strategy. The as-synthesized products show good monodispersion and a large pore volume

[Preparation, quality control and thyroid molecule imaging of solid-target based radionuclide ioine-124].

PubMed

Zhu, H; Wang, F; Guo, X Y; Li, L Q; Duan, D B; Liu, Z B; Yang, Z

2018-04-18

To provide useful information for the further production and application of this novel radio-nuclide for potential clinical application. 124 Te (p,n) 124 I nuclide reaction was used for the 124 I production. Firstly, the target material, 124 TeO 2 (200 mg) and Al2O3 (30 mg) mixture, were compressed into the round platinum based solid target by tablet device. HM-20 medical cyclotron was applied to irradiate the solid target slice for 6-10 h with helium and water cooling. Then, the radiated solid target was placed for 12 h (overnight) to decay the radioactive impurity; finally, 124 I was be purified by dry distillation using 1 mL/min nitrogen for about 6 hours and radiochemical separation methods. Micro-PET imaging studies were performed to investigate the metabolism properties and thyroid imaging ability of 124 I.After 740 kBq 124 I was injected intravenously into the tail vein of the normal mice, the animals were imaged with micro-PET and infused with CT. The micro-PET/CT infusion imaging revealed actual state 124 I's metabolism in the mice. It was been successfully applied for 200 mg 124 TeO 2 plating by the tablet device on the surface of platinum. It showed smooth, dense surface and without obviously pits and cracks. The enriched 124 Te target was irradiated for 6 to 10 hours at about 12.0 MeV with 20 μA current on HM-20 cyclotron. Then 370-1 110 MBq 124 I could be produced on the solid target after irradiation and 370-740 MBq high specific activity could be collected afterdry distillation separation and radio-chemical purification. 124 I product was finally dissolved in 0.01 mol/L NaOH for the future distribution. The gamma spectrum of the produced 124 I-solution showed that radionuclide purity was over 80.0%. The micro-PET imaging of 124 I in the normal mice exhibited the thyroid and stomach accumulations and kidney metabolism, the bladder could also be clearly visible, which was in accordance with what was previously reported. To the best of our knowledge

Formation of hollow silica nanospheres by reverse microemulsion

NASA Astrophysics Data System (ADS)

Lin, Cheng-Han; Chang, Jen-Hsuan; Yeh, Yi-Qi; Wu, Si-Han; Liu, Yi-Hsin; Mou, Chung-Yuan

2015-05-01

Uniform hollow silica nanospheres (HSNs) synthesized with reverse microemulsion have great application potential as nanoreactors because enzymes or nanocatalysts can be easily encapsulated de novo in synthesis. Water-in-oil (w/o) reverse microemulsions comprising the polymeric surfactant polyoxyethylene (5) isooctylphenyl ether (Igepal CA-520), ammonia and water in a continuous oil phase (alkanes) coalesce into size-tunable silica nanoparticles via diffusion aggregation after the introduction of silica precursors. Here, we elucidate in detail the growth mechanism for silica nanoparticles via nucleation of ammonium-catalyzed silica oligomers from tetraethylorthosilicate (TEOS) and nanoporous aminopropyltrimethoxy silane (APTS) in the reverse microemulsion system. The formation pathway was studied in situ with small-angle X-ray scattering (SAXS). We find a four-stage process showing a sigmoidal growth behavior in time with a crossover from the induction period, early nucleation stage, coalescence growth and a final slowing down of growth. Various characterizations (TEM, N2 isotherm, dynamic light scattering, zeta potential, NMR, elemental analysis) reveal the diameters, scattering length density (SLD), mesoporosity, surface potentials and chemical compositions of the HSNs. Oil phases of alkanes with different alkyl chains are systematically employed to tune the sizes of HSNs by varying oil molar volumes, co-solvent amounts or surfactant mixture ratios. Silica condensation is incomplete in the core region, with the silica source of TEOS and APTS leading to the hollow silica nanosphere after etching with warm water.Uniform hollow silica nanospheres (HSNs) synthesized with reverse microemulsion have great application potential as nanoreactors because enzymes or nanocatalysts can be easily encapsulated de novo in synthesis. Water-in-oil (w/o) reverse microemulsions comprising the polymeric surfactant polyoxyethylene (5) isooctylphenyl ether (Igepal CA-520), ammonia and

Implementation of New System for Oxygen Generation and Carbon Dioxide Removal =

NASA Astrophysics Data System (ADS)

Karavolos, Angelo Peter

This research effort develops an integrated system for CO2 removal and O2 production. A unique material, dodeca-tungsto-phosphoric acid (H3PO4W12O3; henceforth referred to as DTPA) is mixed with tetra-ethyl-ortho-silicate Si(OC2H 5)4 or TEOS. This mixture exhibits unique properties of heat absorption and high electrical conductivity. In the system described herein, the DTPA resides within a cross linked arrangement of TEOS. The DTPA furnishes a source of O2, while the TEOS furnishes structural support for the large DTPA crystals. In addition, the large amount of H2O within the crystal also adsorbs CO2. It can also be cross-linked with other polymers such as polycarbonate, for different applications and properties such as flexible textiles. A set of isolated bench experiments were designed to test CO2 adsorption, O2 production, heat production, and voltage production were conducted to test the hypothesis that DTPA can provide CO2 adsorption, O2 generation, heat generation and electrical generation. Five experiments with this apparatus were conducted: (1) a mass balance experiment; (2) an X-ray diffraction experiment; (3) a photo spectroscopic experiment; (4) a calorimetric experiment; and (5) a dielectric experiment. Results illustrate that approximately 2880 grams of this material produces 576 grams of O2, and removes 1760 grams of CO2. The reaction also produces approximately 844 kJ/mole heat, and can supply 12.2 V potential over a period of 4.5 hours. The amount of unused material and the recycling ability suggests the usefulness of the technique to achieve between a 50-75% closed system. In addition, an experiment using 18O tracer demonstrated that approximately 20% of the O2 produced comes from processed CO2 adsorbed by the crystal, while the remaining 80% of the O2 produced comes from replaced O2 within the crystal itself. The device has multiple applications including environmental control and life support for aircraft cabins, space vehicle interiors

Experimental and theoretical approach on the optical properties of zinc borotellurite glass doped with dysprosium oxide.

PubMed

Halimah, M K; Ami Hazlin, M N; Muhammad, F D

2018-04-15

A series of glass samples with chemical formula {[(TeO 2 ) 0.7 (B 2 O 3 ) 0.3 ] 0.7 (ZnO) 0.3 } 1-x (Dy 2 O 3 ) x where x=0.01, 0.02, 0.03, 0.04 and 0.05M fraction were synthesized through conventional melt-quenching method. The most common way to fabricate a glass material is by fusion of two or more component oxides followed by their quenching. This technique is known as melt-quenching technique. Kaur et al. (2016) [1] highlighted that the melt-quenching method able to enhance the mechanical properties like hardness and flexural strength of the material. The nature of the glass systems is proven to be amorphous based on the XRD pattern. The FTIR spectra of the glass systems confirm the existence of five bands which are assigned for the BO 4 , BO 3, TeO 4 and TeO 3 vibrational groups. The density of the glass systems is increased with the addition of Dy 2 O 3 while the molar volume is found to be inversely proportional to the density of the proposed glass. The optical properties of the glasses are determined through the absorption spectra obtained from the UV-VIS spectrophotometer. From the absorption spectra, the indirect and direct optical band gaps and the Urbach energy are found to be inversely proportional to each other. As the molar fraction of the Dy 2 O 3 increased, the optical band gaps are observed to increase as opposed to the Urbach energy. For this glass system, the values of refractive index, electronic polarizability, oxide ion polarizability and the optical basicity are found to decrease as the addition of the dysprosium oxide is increased. From the emission spectra, two intense blue and yellow emission bands are observed, which correspond to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ ions respectively. The CIE chromaticity coordinates of the zinc borotellurite glass systems are found to be located in the white light region. Copyright © 2017 Elsevier B.V. All rights reserved.

Developments in Plasma-Source Mass Spectrometry

DTIC Science & Technology

1988-07-11

Spectrometry 12 PERSONAL AUTHOR(S) Gary M. Hieftje and George H. Vickers 13a. TYPE OF REPORT b.TMCOEE . TEO POTYerMohay 5.AGCUN Technical FROM TO 11 July...4134006 TECHNICAL REPORT NO. 41 DEVELOPMENTS IN PLASMA-SOURCE MASS SPECTROMETRY by Gary M. Hieftje and George H. Vickers Acessoo i or * NTIS GRMX Prepared...G. M. Hieftje , and A. T. Zander, Spectrochim. Acta 1987, 42B, 29 60 Determination of Lead Isotope Ratios by Inductively Coupled Plasma-Mass

21ST International Symposium on Rarefied Gas Dynamics, Marseille (France) 26-31 July 1998. Book of Abstracts, Volume II: Poster Sessions.

DTIC Science & Technology

1998-07-30

for normal oxidation. other surfaces exposed to the fast 0 beam. These results and others clearly show that stoichiomet- nic layers of TeO2 are...to pos- However a detailed analysis shows that results both sibilities for reduction of aerodynamic friction for metal and glass channels with the...P.E., The effect of t e surf ce compos - accommodation coefficient for glass and metal (Ti tion on a free molecular gas flow in a cylin- or Mo) reachs

Infrared fiber coupled acousto-optic tunable filter spectrometer

NASA Technical Reports Server (NTRS)

Levin, K. H.; Kindler, E.; Ko, T.; Lee, F.; Tran, D. C.; Tapphorn, R. M.

1990-01-01

A spectrometer design is introduced which combines an acoustooptic tunable filter (AOTF) and IR-transmitting flouride-glass fibers. The AOTF crystal is fabricated from TeO2 and permits random access to any wavelength in less than 50 microseconds, and the resulting spectrometer is tested for the remote analysis of gases and hydrocarbons. The AOTF spectrometer, when operated with a high-speed frequency synthesizer and optimized algorithms, permits accurate high-speed spectroscopy in the mid-IR spectral region.

Integrated Optical Information Processing

DTIC Science & Technology

1988-08-01

applications in optical disk memory systems [91. This device is constructed in a glass /SiO2/Si waveguide. The choice of a Si substrate allows for the...contact mask) were formed in the photoresist deposited on all of the samples, we covered the unwanted gratings on each sample with cover glass slides...processing, let us consider TeO2 (v, = 620 m/s) as a potential substrate for applications requiring large time delays. This con- sideration is despite

Effect of γ-ray irradiation on optical properties of erbium doped bismuth-tellurite glasses

NASA Astrophysics Data System (ADS)

Keshavamurthy, K.; Eraiah, B.

2018-05-01

Heavy metal oxide contained glasses are very promising candidates in shielding and photonic materials. In this paper, we studied the effect of γ-ray irradiation on optical properties of Er2O3-Bi2O3-TeO2 glasses through UV-Visible spectrophotometer. After γ-ray exposure, the optical band gap decreases and Urbach energy increases, which is due to creation of defects within the glass network as a result increases the number of non-bridging oxygens.

Command History. 1964. Sanitized

DTIC Science & Technology

1964-01-01

AircrRft Inventory, End of 1963 ........ 127 VI US Airevalt Inventory, End of 1964....o...v 128 MAPS Comnercial Systems - Northern and Southern roll...182 11 RVN Telecommunications System ......,.,,, 183 iii Ijetwvah, Backpotch, and Crossbow.. . , 184 ANNEX A Special Operations (PubLishe4...vr o~bt~ en US and Vtotomuso’ i~ustoa., mor~al$, And iý1 41teo 4140- an "tlutloatr to both U.$ avid rown US!- sli0 the jgovornoental ’oroetott .4 the

Safety Evaluation of Enterocin Producer Enterococcus sp. Strains Isolated from Traditional Turkish Cheeses.

PubMed

Avcı, Mine; Özden Tuncer, Banu

2017-07-06

The purpose of this study was to determine the antimicrobial activity and occurrence of bacteriocin structural genes in Enterococcus spp. isolated from different cheeses and also investigate some of their virulence factors. Enterococcus strains were isolated from 33 different cheeses. Enterococcus faecium (6 strains) and Enterococcus faecalis (5 strains) enterocin-producing strains were identified by 16S rDNA analyses. Structural genes entA, entB, entP and entX were detected in some isolates. Multiple enterocin structural genes were found in 7 strains. None of the tested enterococci demonstrated anyβ-haemolytic activity and only one strain had gelatinase activity. Six strains showed multiple antibiotic resistance patterns and in addition, vanA and several virulence genes were detected in many strains. Only E. faecalis MBE1-9 showed tyrosine decarboxylase activity and tdc gene was detected only in this strain.

Record of gut associated nemathelminth in the giant African snail Achatina fulica (Bowdich) from Bangalore, India.

PubMed

Jayashankar, M; Murthy, G S S

2015-06-01

Prevalence of nematodes in Achatina fulica (Bowdich) sample collected from two different sites within Bangalore University Jnana Bharathi Campus viz., Dhanavanthari vana and Botany Department garden was 84 and 100 % respectively. However, the identity of the nemathelminth could not be established to the species level as it did not respond to the clearing agent and its genital organs were not located which is key character for taxonomic identification. Also, no Cercariae were recorded in the samples, perhaps the snail sample was non endemic for parasitic population. Helminthological prospection with regard to the giant African snail from the region has not been performed till date. The present work is a preliminary study in that direction intended to determine the nemathelminth fauna associated with A. fulica populations in Bangalore region laying emphasis on further studies to be undertaken in this regard.

Photoinduced piezooptics effect in TeO2-Ga2O3 glasses

NASA Astrophysics Data System (ADS)

Ozga, K.; Fedorchuk, A. O.; Armand, P.

2015-08-01

We have found that during the bicolor illumination by two boicolor coherent wavelengths 1540 nm/770 nm there occurred substantial changes of the elastooptical non-diagonal coefficients at 1150 nm cw laser wavelength. They are maximal at power densities 400 … 500 MW/cm2. The studies have shown that the maximal effect exists for ultra-fast quenching glasses and occurs after the 1-2 min of the treatment. The switching off of the optical treatment leads to the disappearance of the photoinduced piezooptics at about 100 ms. The observed changes are explained within the photoinduced changes of the charge density distribution for the principal structural clusters within a framework of the DFT approach. The studies were done both for diagonal as well as off-diagonal piezooptical effect (POE) tensor components.

"Two Exemptions and One Subsidy" (TEOS): Voices from a Grass-Roots School

ERIC Educational Resources Information Center

Dan, Wang

2008-01-01

Chaoyang township is one of the poorest townships in a national-level impoverished county in the southwest. Statistics show that the average per capita income for farming families was RMB1,931 per year in 2006. Before the highway came through the area, the residents of Chaoyang township had to walk for two whole days across mountain ranges to get…

From "Teo" to "Harry Potter": Books in Spanish for Children and Adolescents.

ERIC Educational Resources Information Center

Schon, Isabel

2001-01-01

Presents a listing of Spanish-language books for children and adolescents recently published in Mexico, Venezuela, Spain, Colombia, and Argentina. The books are categorized as biography, history, historical fiction, folklore, poetry, religion, fiction, and literature for the very young. (SM)

A Sol-Gel-Modified Poly(methyl methacrylate) Electrophoresis Microchip with a Hydrophilic Channel Wall

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

Chen, Gang; Xu, Xuejiao; Lin, Yuehe

2007-07-27

A sol-gel method was employed to fabricate a poly(methyl methacrylate) (PMMA) electrophoresis microchip that contains a hydrophilic channel wall. To fabricate such a device, tetraethoxysilane (TEOS) was injected into the PMMA channel and was allowed to diffuse into the surface layer for 24 h. After removing the excess TEOS, the channel was filled with an acidic solution for 3 h. Subsequently, the channel was flushed with water and was pretreated in an oven to obtain a sol-gel-modified PMMA microchip. The water contact angle for the sol-gel-modified PMMA was 27.4° compared with 66.3° for the pure PMMA. In addition, the electro-osmoticmore » flow increased from 2.13×10-4 cm2 V-1 s-1 for the native-PMMA channel to 4.86×10-4 cm2 V-1 s-1 for the modified one. The analytical performance of the sol-gel-modified PMMA microchip was demonstrated for the electrophoretic separation of several purines, coupled with amperometric detection. The separation efficiency of uric acid increased to 74 882.3 m-1 compared with 14 730.5 m-1 for native-PMMA microchips. The result of this simple modification is a significant improvement in the performance of PMMA for microchip electrophoresis and microfluidic applications.« less

Preparation of Water-Repellent Glass by Sol-Gel Process Using Perfluoroalkylsilane and Tetraethoxysilane.

PubMed

Jeong, Hye-Jeong; Kim, Dong-Kwon; Lee, Soo-Bok; Kwon, Soo-Han; Kadono, Kohei

2001-03-01

Coating films on glass substrate were prepared by sol-gel process using alkoxide solutions containing perfluoroalkylsilane (PFAS) and tetraethoxysilane (TEOS). The physical properties of the coating films were characterized by SEM, FT-IR, and XRD. And their surface properties were investigated by measuring contact angles and atomic compositions. Transparent coating films with smooth surface and uniform thickness could be obtained. The contact angles of the coating films for water and methylene iodide are extremely high, at 118 degrees and 97 degrees, respectively, and their surface free energies are about 9.7 dyn/cm. It was found that the water-repellent glass prepared is very hydrophobic and exhibits excellent water-repellency. Hydrophobic perfluoroalkyl groups are preferentially enriched to the outermost layer at the coating film-air interface, and two layers probably exist in the coating film. The upper layer oriented toward the air is composed of mainly perfluoroalkyl groups originating from PFAS, and the lower layer is composed of mainly -OSiO- groups originating from TEOS. The heat treatment after drying step cannot influence the surface enrichment of the perfluoroalkyl group. The hydrolysis reaction should be more completely done before the dip coating step to obtain lower surface free energy. The burning temperature should be less than 300 degrees C because the perfluoroalkyl group begins to decompose from this temperature. Copyright 2001 Academic Press.

One-Step Synthesis of Cagelike Hollow Silica Spheres with Large Through-Holes for Macromolecule Delivery.

PubMed

Wang, Shengnan; Chen, Min; Wu, Limin

2016-12-07

A facile, one-step method to prepare cagelike hollow silica nanospheres with large through-holes (HSNLs) using a lysozyme-assisted O/W miniemulsion technique is presented. The tetraethoxysilane (TEOS)-xylene mixture forms oil droplets which are stabilized by the cationic surfactant cetyltrimethylammonium bromide (CTAB), cosurfactant hexadecane (HD), and protein lysozyme. HSNLs (with diameter of 300-460 nm) with large through-holes (10-30 nm) were obtained directly after ultrasonic treatment and aging. Lysozyme can not only stabilize the oil/water interface, assist the hydrolysis of TEOS, and interact with silica particles to assemble into silica-lysozyme clusters but also contribute to the formation of through-holes due to its hydrophilicity variation at different pH conditions. A possible new mechanism called the interface desorption method is proposed to explain the formation of the through-holes. To confirm the effectiveness of large through-holes in delivering large molecules, bovine serum albumin (BSA, 21 × 4 × 14 nm 3 ) was chosen as a model guest molecule; HSNLs showed much higher loading capacity compared with common hollow mesoporous silica nanospheres (HMSNs). The release of BSA can be well controlled by wrapping HSNLs with a heat-sensitive phase change material (1-tetradecanol). Cell toxicity was also conducted with a Cell Counting Kit-8 (CCK-8) assay to roughly evaluate the feasibility of HSNLs in biomedical applications.

Surface modification of quartz fibres for dental composites through a sol-gel process.

PubMed

Wang, Yazi; Wang, Renlin; Habib, Eric; Wang, Ruili; Zhang, Qinghong; Sun, Bin; Zhu, Meifang

2017-05-01

In this study, quartz fibres (QFs) surface modification using a sol-gel method was proposed and dental posts reinforced with modified QFs were produced. A silica sol (SS) was prepared using tetraethoxysilane (TEOS) and 3-methacryloxypropyltrimethoxysilane (γ-MPS) as precursors. The amount of γ-MPS in the sol-gel system was varied from 0 to 24wt.% with a constant molar ratio of TEOS, ethanol, deionized water, and HCl. Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and contact angle (CA) measurements were used to characterize the modified QFs, which confirmed that SS had successfully coated the surface of QFs. SEM images showed good interfacial bonding between the modified QFs and the resin matrix. The results of three-point bending tests of the fibre reinforced composite (FRC) posts showed that the QFs modified by SS with 12wt.% γ-MPS presented the best mechanical properties, demonstrating improvements of 108.3% and 89.6% for the flexural strength and flexural modulus, respectively, compared with untreated QFs. Furthermore, the sorption and solubility of the prepared dental posts were also studied by immersing the posts in artificial saliva (AS) for 4weeks, and yielded favourable results. This sol-gel surface modification method promises to resolve interfacial bonding issues of fibres with the resin matrix, and produce FRC posts with excellent properties. Copyright © 2017. Published by Elsevier B.V.

Supercontinuum generation covering the entire 0.4-5 µm transmission window in a tapered ultra-high numerical aperture all-solid fluorotellurite fiber

NASA Astrophysics Data System (ADS)

Jia, Z. X.; Yao, C. F.; Jia, S. J.; Wang, F.; Wang, S. B.; Zhao, Z. P.; Liao, M. S.; Qin, G. S.; Hu, L. L.; Ohishi, Y.; Qin, W. P.

2018-02-01

Enormous efforts have been made to realize supercontinuum (SC) generation covering the entire transmission window of fiber materials for their wide applications in many fields. Here we demonstrate ultra-broadband SC generation from 400 to 5140 nm in a tapered ultra-high numerical aperture (NA) all-solid fluorotellurite fiber pumped by a 1560 nm mode-locked fiber laser. The fluorotellurite fibers are fabricated using a rod-in-tube method. The core and cladding materials are TeO2-BaF2-Y2O3- and TeO2-modified fluoroaluminate glasses, respectively, which have large refractive index contrast and similar thermal expansion coefficients and softening temperatures. The NA at 3200 nm of the fluorotellurite fiber is about 1.11. Furthermore, tapered fluorotellurite fibers are prepared using an elongation machine. SC generation covering the entire 0.4-5 µm transmission window is achieved in a tapered fluorotellurite fiber for a pumping peak power of ~10.5 kW through synergetic control of dispersion, nonlinearity, confinement loss and other unexpected effects (e.g. the attachment of dust or water to the surface of the fiber core) of the fiber. Our results show that tapered ultra-high NA all-solid soft glass fibers have a potential for generating SC light covering their entire transmission window.

Novel Co:MgF2 lidar for aerosol profiler

NASA Technical Reports Server (NTRS)

Acharekar, M. A.

1993-01-01

Lidars are of great interest because of their unique capabilities in remote sensing applications in sounding of the atmosphere, meteorology, and climatology. In this small business innovative research (SBIR) phase II program, laser sources including Co:MgF2, CTH:YAG, CTH:YSGG, CT:YAG, and Er:Glass were evaluated. Modulator of fused silica and TeO2 materials with Brewster's angle end faces were used with these lasers as acousto-optical (AO) Q-switches. A higher hold-off energy and hence a higher Q-switched energy was obtained by using a high power RF driver. The report provides performance characteristics of these lasers. The tunable (1.75-2.50 microns) Co:MgF2 laser damaged the TeO2 Q-switch cell. However, the CTH:YAG laser operating at 2.09 microns provided output energy of over 300 mJ/p in 50 ns pulse width using the fused silica Q-switch. This Q-switched CTH:YAG laser was used in a breadboard vertical aerosol profiler. A 40 cm diameter telescope, InSb and InGaAs detectors were used in the receiver. The data obtained using this lidar is provided in the report. The data shows that the eye safe lidar using CTH:YAG laser for the vertical aerosol density and range measurements is the viable approach.

Top-down beta oscillatory signaling conveys behavioral context in early visual cortex.

PubMed

Richter, Craig G; Coppola, Richard; Bressler, Steven L

2018-05-03

Top-down modulation of sensory processing is a critical neural mechanism subserving numerous important cognitive roles, one of which may be to inform lower-order sensory systems of the current 'task at hand' by conveying behavioral context to these systems. Accumulating evidence indicates that top-down cortical influences are carried by directed interareal synchronization of oscillatory neuronal populations, with recent results pointing to beta-frequency oscillations as particularly important for top-down processing. However, it remains to be determined if top-down beta-frequency oscillations indeed convey behavioral context. We measured spectral Granger Causality (sGC) using local field potentials recorded from microelectrodes chronically implanted in visual areas V1/V2, V4, and TEO of two rhesus macaque monkeys, and applied multivariate pattern analysis to the spatial patterns of top-down sGC. We decoded behavioral context by discriminating patterns of top-down (V4/TEO-to-V1/V2) beta-peak sGC for two different task rules governing correct responses to identical visual stimuli. The results indicate that top-down directed influences are carried to visual cortex by beta oscillations, and differentiate task demands even before visual stimulus processing. They suggest that top-down beta-frequency oscillatory processes coordinate processing of sensory information by conveying global knowledge states to early levels of the sensory cortical hierarchy independently of bottom-up stimulus-driven processing.

Silk flame retardant finish by ternary silica sol containing boron and nitrogen

NASA Astrophysics Data System (ADS)

Zhang, Qiang-hua; Chen, Guo-qiang; Xing, Tie-ling

2017-11-01

A ternary flame retardant sol system containing Si, B and N was prepared via sol gel method using tetraethoxysilane (TEOS) as a precursor, boric acid (H3BO3) and urea (CO(NH2)2) as flame retardant additives and then applied to silk fabric flame retardant finish. The FT-IR and SEM results showed that the nitrogen-boron-silica ternary sol was successfully prepared and entrapped onto the surface of silk fibers. The limiting oxygen index (LOI) test indicated that the silk fabric treated with 24% boric acid and 6% urea (relative to the TEOS) doped ternary silica sol system performed excellent flame retardancy with the LOI value of 34.6%. Furthermore, in order to endow silk fabric with durable flame retardancy, the silk fabric was pretreated with 1,2,3,4-butanetetracarboxylic acid (BTCA) before the ternary sol system treatment. The BTCA pretreat ment applied to silk could effectively promote the washing durability of the ternary sol, and the LOI value of the treated sample after 10 times washing could still maintain at 30.8% compared with that of 31.0% before washing. Thermo gravimetric (TG), micro calorimeter combustion (MCC) and smoke density test results demonstrated that the thermal stability, heat release and smoke suppression of the nitrogen-boron-silica ternary system decreased somewhat compared with the boron-silica binary flame retardant system.

Optimization of sol-gel medium for entrapment of acetylcholinesterase enzyme in biosensor for pesticide detection

NASA Astrophysics Data System (ADS)

Wijayanti, S. D.; Rahayu, F. S.; Widyaningsih, T. D.

2018-03-01

Pesticides are chemical substances used to kill and control pests or diseases that can damage crops. The use of pesticides should be done precisely because the accumulation of chemicals contained in pesticides can cause various health effects. Therefore, detection of pesticide residues on plants is important to reduce the risk of poisoning due to pesticide residues. Some of the conventional methods that have been done to detect pesticide residues have weaknesses among expensive tools, takes a long time, and are generally performed by trained laboratory technicians. Biosensors are analytical devices that can measure the quantitative or semi-quantitative targets of analyte by utilizing a bioreceptor such as enzyme. Several studies have shown that enzyme-based acetylcholinesterase-based biosensors can be used to detect pesticide residues in vegetable samples. The objective of this research was to get a proper silica based sol-gel formulation with molar ratio of H2O:TEOS and NaOH concentration as immobilization medium of acetylcholinesterase enzyme for biosensor application. Response Surface Methodology (RSM) was used in order to determine the interaction between the parameters studied and resulting responses which were amount and activity of acetylcholinesterase enzyme. Based on the research, the best result for immobilized enzyme activity was shown by molar ratio (H2O: TEOS) 1: 8 and 4 mM NaOH treatment.

Investigations on photolon-and porphyrin-doped sol-gel fiberoptic coatings for laser-assisted applications in medicine

NASA Astrophysics Data System (ADS)

Bindig, U.; Ulatowska-Jarza, A.; Kopaczynska, M.; Müller, G.; Podbielska, H.

2008-01-01

In view of laser-assisted medical applications, the construction of silica-based sol-gel fiberoptic sensors based on photolon (Ph) and protoporphyrin IX (PP IX) is discussed. Electron microscopy and AFM were used to characterize the silica sol-gel coatings. AFM measurements indicate a change in the surface porosity. The PP IX-based sensors were constructed as a one-layer optode as well as a multilayered structure. An additional hybrid sensor made up of alternate layers of PP IX-and Ph-doped sol-gel was also constructed and examined. Sol-gel matrices were prepared from silicate precursor tetraethylorthosilicate (TEOS) mixed with ethanol in acid-catalyzed hydrolysis. The carrier matrices of photosensitive dyes were produced with factor R = 20, where R denotes the ratio of solvent moles (ethanol) to the number of TEOS moles. A multilayered coating was built up using the reverse-dipping technique. The overall coating thickness was determined by electron microscopy. Doped sol-gels with different PP IX concentrations were used to produce fiberoptic coatings. The film optodes with a different number of layers were examined by fluorescence spectroscopy. It was found that photolon and protoporphyrin IX entrapped in sol-gel preserve their chemical reactivity and have contact with the external environment. The hybrid sensor demonstrated clear fluorescence and a reversible behavior in gaseous environments.

Hierarchical Biosilicates by the 3-D Replication of Block Copolymer Templates in Supercritical Fluids

DTIC Science & Technology

2009-12-30

Iron Oxide Nanoparticles through Supercritical CO2 Infusion of TEOS into Ferritin Doped Block Copolymers…………………………………………………...4 4.2 Simple...which is doped with ferritin (yellow spheres). The blue PPO domains are removed during calcination as is the apoferritin shell, leaving magnetic...iron oxide particles (black) embedded in the mesoporous silica film. 5 2 TEM images of ferritin -containing samples at the specified ferritin

Influence of Boehmite Precursor on Aluminosilicate Aerogel Pore Structure, Phase Stability and Resistance to Densification at High Temperatures

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.; Guo, Haiquan; Newlin, Katy N.

2011-01-01

Aluminosilicate aerogels are of interest as constituents of thermal insulation systems for use at temperatures higher than those attainable with silica aerogels. It is anticipated that their effectiveness as thermal insulators will be influenced by their morphology, pore size distribution, physical and skeletal densities. The present study focuses on the synthesis of aluminosilicate aerogel from a variety of Boehmite (precursors as the Al source, and tetraethylorthosilicate (TEOS) as the Si source, and the influence of starting powder on pore structure and thermal stability.

Rare-Earth Oxide Ion (Tm3+, Ho3+, and U3+) Doped Glasses and Fibres for 1.8 to 4 Micrometer Coherent and Broadband Sources

DTIC Science & Technology

2006-07-24

oxide ( TeO2 ) , fluorine- containing silicate (SiOF2) and germanate (GeOF2) glass hosts for each dopant by characterising the spectroscopic properties...Earth Oxide Ion (Tm3+, Ho3+, And U3+) Doped Glasses And Fibres For 1.8 To 4 Micrometer Coherent And Broadband Sources 5c. PROGRAM ELEMENT NUMBER 5d...Rare-earth oxide ion (Tm3+, Ho3+, and U3+) doped glasses and fibres for 1.8 to 4 micrometer coherent and broadband sources Report prepared

JPRS Report, Science and Technology: China.

DTIC Science & Technology

1989-03-17

Optical Absorption Property of TiO -Doped Vycor Glass [Ling Ping, et al.; WULI XUEBAO, No 11, Nov 88] ......... 81 Generation of Short Pulse of 30 fs...et al.; YINGYONG JIGUANG, No 6, Dec 88] 94 High-Resolution TeO2 Acousto-Optic Deflector for mm-Wave Radio Spectrometer [Xu Binghuo, et al.; YINGYONG...Nov 88] ......... 159 Study of Structural Relaxation of Metallic Glass (Feo. 8 5Nio.15)84 B1 6 by Measuring Thermal Expansion, Resistance Under Zero

Navy’s Advanced Aircraft Armament System Program Concept Objectives

DTIC Science & Technology

1983-10-01

12-1 00 NAVY’S ADVANCED AIRCRAFT ARMAMENT SYSTEM PROGRAM CONCEPT OBJECTIVES T. M . Leese and J. F. Haney Naval Weapons Center Code 31403 China...STORE FLWNT LIFE RECONFIOURATION ♦ UWMST OMHTH ninoairv M — MANN HUCTHM ^♦■ SILECT ALTERNATE • STORE 0PTI0M ■ REOUCIO CK« W0RKL0A0 • . README...mOVEMENTS INÜTEO FUIWUTY MM AM tTATWM COMPLEX AUTOMATIC LACK OF OIT RESTRICTIVE MLNIRV M FLUWAITV IUCSMVI Figure 1. Carrier aircraft

Indian Mountain AFS, Alaska. Revised Uniform Summary of Surface Weather Observations (RUSSWO). Parts A-F.

DTIC Science & Technology

1983-06-01

tT A: CSURFACE WINDS AlY .EAT" 1, SEPV;C’./- kC PERCENTAGE FREQUENCY OF WIND DIRECTION AND SPEED (FROM HOURLY OBSERVATIONS) V ? -> \\l A ~i’, T A I N A...1 0 21 -22 23 24 25 2627 28 29.30 31 , o, . - - FE-r.Z X No. Obs. Mo. No. of No-.. -%8 Teo ,at-rv. R&H-. F 32 F 67 F *73 F *80 F *93 F To D,v B-b S

Molecular characterization of antimicrobial resistance genes against Staphylococcus aureus isolates from Trinidad and Tobago.

PubMed

Akpaka, Patrick E; Roberts, Rashida; Monecke, Stefan

Staphylococcus aureus continues to pose major public health challenges in many areas because of antibiotic resistance problems. In the Caribbean, especially Trinidad and Tobago, the challenge is not different. This study was performed to evaluate the antimicrobial resistance gene prevalence among S. aureus isolates in Trinidad and Tobago. Standard and molecular microbiological methods, including the Microscan automated system, DNA microarray and multi locus sequence typing (MLST) analysis, were performed on 309 clinical S. aureus isolates recovered from patients who were treated at three of the country's main health institutions. S. aureus exhibited susceptibilities ≥80% to eleven of the 19 antimicrobials tested against it, and these belong to the most commonly used and available antibiotics in the country. While the antibiotic to which it was most susceptible of the commonly used antibiotics was trimethoprim/sulfamethoxazole, the antibiotics to which it was least susceptible or most resistant to were ampicillin and penicillin. S. aureus isolates from the pediatric ward produced the greatest rate of susceptibility among the isolates recovered from patients admitted into hospitals, while isolates from Accident and Emergency rooms displayed the greatest susceptibilities among patients from the community. S. aureus isolates from the country did not harbor acquired resistant genes targeting clindamycin/macrolides (ermB), linezolid (cfr) or vancomycin (vanA). The blaZ gene, which is the most common beta lactam (Penicillinase) resistance mechanism for S. aureus, was observed in 88.7% of the methicillin susceptible S. aureus, while methicillin resistance mediated by the mec gene was present in 13.6%. Most of the resistance markers found in MRSA isolates were significantly associated with the ST239-MRSA-III strain in this study, and all isolates that belonged to the USA300 strain, which additionally encoded both the PVL gene and ACME cluster, belonged to CC8. Several

Development of a heptaplex PCR assay for identification of Staphylococcus aureus and CoNS with simultaneous detection of virulence and antibiotic resistance genes.

PubMed

Okolie, Charles Emeka; Wooldridge, Karl G; Turner, David P J; Cockayne, Alan; James, Richard

2015-08-05

Staphylococcal toxicity and antibiotic resistance (STAAR) have been menacing public health. Although vancomycin-resistant Staphylococcus aureus (VRSA) is currently not as widespread as methicillin-resistant S. aureus (MRSA), genome evolution of MRSA into VRSA, including strains engineered within the same patient under anti-staphylococcal therapy, may build up to future public health concern. To further complicate diagnosis, infection control and anti-microbial chemotherapy, non-sterile sites such as the nares and the skin could contain both S. aureus and coagulase-negative staphylococci (CoNS), either of which could harbour mecA the gene driving staphylococcal methicillin-resistance and required for MRSA-VRSA evolution. A new heptaplex PCR assay has been developed which simultaneously detects seven markers for: i) eubacteria (16S rRNA), ii) Staphylococcus genus (tuf), iii) Staphylococcus aureus (spa), iv) CoNS (cns), v) Panton-Valentine leukocidin (pvl), vi) methicillin resistance (mecA), and vii) vancomycin resistance (vanA). Following successful validation using 255 reference bacterial strains, applicability to analyse clinical samples was evaluated by direct amplification in spiked blood cultures (n = 89) which returned 100 % specificity, negative and positive predictive values. The new assay has LoD of 1.0x10(3) CFU/mL for the 16S rRNA marker and 1.0x10(4) CFU/mL for six other markers and completes cycling in less than one hour. The speed, sensitivity (100 %), NPV (100 %) and PPV (100 %) suggest the new heptaplex PCR assay could be easily integrated into a routine diagnostic microbiology workflow. Detection of the cns marker allows for unique identification of CoNS in mono-microbial and in poly-microbial samples containing mixtures of CoNS and S. aureus without recourse to the conventional elimination approach which is ambiguous. In addition to the SA-CoNS differential diagnostic essence of the new assay, inclusion of vanA primers will allow

Total Internal Reflection Ultrasonic Sensor for Detection of Subsurface Flaws: Proof of Concept

DTIC Science & Technology

2010-01-01

34 Tv001 Ve group (ray) velocity of the elastic wave X1, X2, X3 crystallographic coordinates x, y, z Descartes ’ coordinates tied to the transducer y0...TeO2 prism. 1.2.1. Orientation of directions and planes of interest with respect to Descartes ’ and Spherical coordinates. 1.2.2. Reflection of the...spect to Descartes ’ and Spherical coordi- nates. , (1.2.1) lili uuv Γ=ρ 2 where ρ is the crystal density and the symmetrical second rank Christoffel

Silica coatings on clarithromycin.

PubMed

Bele, Marjan; Dmitrasinovic, Dorde; Planinsek, Odon; Salobir, Mateja; Srcic, Stane; Gaberscek, Miran; Jamnik, Janko

2005-03-03

Pre-crystallized clarithromycin (6-O-methylerythromycin A) particles were coated with silica from the tetraethyl orthosilicate (TEOS)-ethanol-aqueous ammonia system. The coatings had a typical thickness of 100-150 nm and presented about 15 wt.% of the silica-drug composite material. The properties of the coatings depended on reactant concentration, temperature and mixing rate and, in particular, on the presence of a cationic surfactant (cetylpyridinium chloride). In the presence of cetylpyridinium chloride the silica coatings slightly decreased the rate of pure clarithromycin dissolution.

New oxyfluorotellurates(IV): MTeO3F (M = FeIII, GaIII and CrIII).

PubMed

Laval, Jean Paul; Jennene Boukharrata, Nefla; Thomas, Philippe

2008-02-01

The crystal structures of the new isomorphous compounds iron(III) oxyfluorotellurate(IV), FeTeO(3)F, gallium(III) oxyfluorotellurate(IV), GaTeO(3)F, and chromium(III) oxyfluorotellurate(IV), CrTeO(3)F, consist of zigzag chains of MO(4)F(2) distorted octahedra alternately sharing O-O and F-F edges and connected via TeO(3) trigonal pyramids. A full O/F anionic ordering is observed and the electronic lone pair of the Te(IV) cation is stereochemically active.