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Sample records for absorption properties compared

  1. A comparative study of one- and two-photon absorption properties of pyrene and perylene diimide derivatives.

    PubMed

    Liu, Xiao-Ting; Zhao, Yang; Ren, Ai-Min; Feng, Ji-Kang

    2011-06-01

    Two important classes of organic molecules, perylene diimide (PDI) and pyrene derivatives have been found to possess relatively excellent photophysical and photochemical properties and especially high two-photon absorption cross sections (δ(T)(max)). Herein, one-photon absorption (OPA) and two-photon absorption (TPA) properties of some novel PDI and pyrene derivatives were comparatively investigated by the density functional theory (DFT) and Zerner's intermediate neglect of differential overlap (ZINDO) methods. The calculated results indicate that with respect to PDI derivatives, the maximum TPA cross-sections for pyrene compounds increase obviously, the maximum peaks of OPA and TPA spectra are blue-shifted, the ΔE(H-L) (energy gaps between the highest occupied orbital and the lowest unoccupied orbital) increase. The different π-conjugated bridges (fluorene and pyrene) and terminal groups have slight effect on the OPA properties. Nevertheless, the molecules bearing 1,6-disubstituted pyrene as the π-conjugated bridge display the largest δ(T)(max) in both series of compounds 3 and 4. Moreover, the δ(T)(max) values of molecules with benzothiazole-substituted terminal groups are larger than those of the molecules with diphenylamine, which is attributed to benzothiazole groups stabilizing the planarity of the branch parts, extending the conjugated length and increasing the π-electron delocalized extent. Furthermore, the molecular size has marked effect on OPA and TPA properties. It is worthy to mention that cruciform 8 displays the largest δ(T)(max) among all the studied molecules in the range of 600-1100 nm. This research could provide a better understanding for the origin of the linear and nonlinear optical properties, and it would be helpful to gain more information about designing two-photon absorption materials with large δ(T)(max).

  2. Comparative Evaluation of Effect of Water Absorption on the Surface Properties of Heat Cure Acrylic: An in vitro Study

    PubMed Central

    Chandu, G S; Asnani, Pooja; Gupta, Siddarth; Faisal Khan, Mohd.

    2015-01-01

    Background: Use of alkaline peroxide denture cleanser with different temperature of water could cause a change in surface hardness of the acrylic denture and also has a bleaching effect. The purpose of the study was to determine the effect of increased water content during thermal cycling of hot water-treated acrylic on the surface hardness of acrylic denture base when compared to warm water treated acrylic. And to compare the bleaching effect of alkaline peroxide solution on the acrylic denture base on hot water and warm water treated acrylic. Materials and Methods: Forty samples (10 mm × 10 mm × 2.5 mm) were prepared. After the calculation of the initial hardness 40 samples, each was randomly assigned to two groups. Group A: 20 samples were immersed in 250 ml of warm distilled water at 40°C with alkaline peroxide tablet. Group B: 20 samples were immersed in 250 ml of hot distilled water at 100°C with alkaline peroxide tablet. The surface hardness of each test sample was obtained using the digital hardness testing machine recording the Rockwell hardness number before the beginning of the soaking cycles and after completion of 30 soak cycles and compared. Values were analyzed using paired t-test. Five samples from the Group A and five samples from Group B were put side by side and photographed using a Nikon D 40 digital SLR Camera and the photographs were examined visually to assess the change in color. Results: Acrylic samples immersed in hot water showed a statistically significant decrease of 5.8% in surface hardness. And those immersed in warm water showed a statistically insignificant increase of 0.67% in surface hardness. Samples from the two groups showed clinically insignificant difference in color when compared to each other on examination of the photographs. Conclusion: Thermocycling of the acrylic resin at different water bath temperature at 40°C and 100°C showed significant changes in the surface hardness. PMID:25954074

  3. Neutron scattering and absorption properties

    SciTech Connect

    Holden, N.E.

    1993-12-01

    The Table in this report presents an evaluated set of values for the experimental quantities, which characterize the properties for scattering and absorption of neutrons. The neutron cross section is given for room temperature neutrons, 20.43{degree}C, corresponds to a thermal neutron energy of 0.0253 electron volts (eV) or a neutron velocity of 2200 meters/second. The neutron resonance integral is defined over the energy range from 0.5 eV to 0.1 {times} 10{sup 6} eV, or 0.1 MeV. A list of the major references used is given below. The literature cutoff data is October 1993. Uncertainties are given in parentheses. Parentheses with two or more numbers indicate values to the excited states(s) and to the ground state of the product nucleus.

  4. A comparative study of optical absorption and photocatalytic properties of nanocrystalline single-phase anatase and rutile TiO{sub 2} doped with transition metal cations

    SciTech Connect

    Kernazhitsky, L.; Shymanovska, V.; Gavrilko, T.; Naumov, V.; Kshnyakin, V.; Khalyavka, T.

    2013-02-15

    The effect of nanocrystalline TiO{sub 2} doping with transition metal cations (Cu{sup 2+}, Fe{sup 3+}, Co{sup 2+}, Cr{sup 3+}) on their optical absorption and photocatalytic properties was investigated. The obtained metal-doped TiO{sub 2} samples were characterized by X-ray diffraction, scanning electron microscopy, and UV-vis absorption spectroscopy. It is shown that doping effect on anatase (A) and rutile (R) properties is quite different, being much stronger and complicated on A than on R. Contrary to doped R, doped A revealed a significant red shift of the absorption edge along with the band gap narrowing. Photocatalytic activity of anatase increases upon doping in the order: AR/Co>R/Cu>R/Fe>R/Cr, indicating the inhibitory effect of impurity cations. This fact correlates with the decrease in the UV absorption of the doped rutile in the region of the Hg-lamp irradiation at 4.88 eV. - Graphical abstract: A red shift of the absorption edge of nanocrystalline single-phase anatase after doping with transition metal cations. Highlights: Black-Right-Pointing-Pointer Single-phase anatase and rutile powders surface-doped with transition metal cations. Black-Right-Pointing-Pointer Absorption edge and band gap of rutile do not change with surface doping. Black-Right-Pointing-Pointer Band gap of surface-doped anatase reduces being the lowest for A/Fe. Black-Right-Pointing-Pointer The surface-doping improves photocatalytic activity of anatase. Black-Right-Pointing-Pointer The surface-doping inhibits photocatalytic activity of rutile.

  5. Light absorption properties and absorption budget of Southeast Pacific waters

    NASA Astrophysics Data System (ADS)

    Bricaud, Annick; Babin, Marcel; Claustre, Hervé; Ras, JoséPhine; TièChe, Fanny

    2010-08-01

    Absorption coefficients of phytoplankton, nonalgal particles (NAPs), and colored dissolved organic matter (CDOM), and their relative contributions to total light absorption, are essential variables for bio-optical and biogeochemical models. However, their actual variations in the open ocean remain poorly documented, particularly for clear waters because of the difficulty in measuring very low absorption coefficients. The Biogeochemistry and Optics South Pacific Experiment (BIOSOPE) cruise investigated a large range of oceanic regimes, from mesotrophic waters around the Marquesas Islands to hyperoligotrophic waters in the subtropical gyre and eutrophic waters in the upwelling area off Chile. The spectral absorption coefficients of phytoplankton and NAPs were determined using the filter technique, while the CDOM absorption coefficients were measured using a 2 m capillary waveguide. Over the whole transect, the absorption coefficients of both dissolved and particulate components covered approximately two orders of magnitude; in the gyre, they were among the lowest ever reported for open ocean waters. In the oligotrophic and mesotrophic waters, absorption coefficients of phytoplankton and NAPs were notably lower than those measured in other oceanic areas with similar chlorophyll contents, indicating some deviation from the standard chlorophyll-absorption relationships. The contribution of absorption by NAPs to total particulate absorption showed large vertical and horizontal variations. CDOM absorption coefficients covaried with algal biomass, albeit with a high scatter. The spectral slopes of both NAP and CDOM absorption revealed structured spatial variability in relation with the trophic conditions. The relative contributions of each component to total nonwater absorption were (at a given wavelength) weakly variable over the transect, at least within the euphotic layer.

  6. Microwave absorption properties of Ni/(C, silicides) nanocapsules

    PubMed Central

    2012-01-01

    The microwave absorption properties of Ni/(C, silicides) nanocapsules prepared by an arc discharge method have been studied. The composition and the microstructure of the Ni/(C, silicides) nanocapsules were determined by means of X-ray diffraction, X-ray photoelectric spectroscopy, and transmission electron microscope observations. Silicides, in the forms of SiOx and SiC, mainly exist in the shells of the nanocapsules and result in a large amount of defects at the ‘core/shell’ interfaces as well as in the shells. The complex permittivity and microwave absorption properties of the Ni/(C, silicides) nanocapsules are improved by the doped silicides. Compared with those of Ni/C nanocapsules, the positions of maximum absorption peaks of the Ni/(C, silicides) nanocapsules exhibit large red shifts. An electric dipole model is proposed to explain this red shift phenomenon. PMID:22548846

  7. Microwave absorption properties of Ni/(C, silicides) nanocapsules

    NASA Astrophysics Data System (ADS)

    Jiang, Jingjing; Wang, Han; Guo, Huaihong; Yang, Teng; Tang, Wen-Shu; Li, Da; Ma, Song; Geng, Dianyu; Liu, Wei; Zhang, Zhidong

    2012-05-01

    The microwave absorption properties of Ni/(C, silicides) nanocapsules prepared by an arc discharge method have been studied. The composition and the microstructure of the Ni/(C, silicides) nanocapsules were determined by means of X-ray diffraction, X-ray photoelectric spectroscopy, and transmission electron microscope observations. Silicides, in the forms of SiOx and SiC, mainly exist in the shells of the nanocapsules and result in a large amount of defects at the `core/shell' interfaces as well as in the shells. The complex permittivity and microwave absorption properties of the Ni/(C, silicides) nanocapsules are improved by the doped silicides. Compared with those of Ni/C nanocapsules, the positions of maximum absorption peaks of the Ni/(C, silicides) nanocapsules exhibit large red shifts. An electric dipole model is proposed to explain this red shift phenomenon.

  8. Microwave absorption properties of Ni/(C, silicides) nanocapsules.

    PubMed

    Jiang, Jingjing; Wang, Han; Guo, Huaihong; Yang, Teng; Tang, Wen-Shu; Li, Da; Ma, Song; Geng, Dianyu; Liu, Wei; Zhang, Zhidong

    2012-05-01

    The microwave absorption properties of Ni/(C, silicides) nanocapsules prepared by an arc discharge method have been studied. The composition and the microstructure of the Ni/(C, silicides) nanocapsules were determined by means of X-ray diffraction, X-ray photoelectric spectroscopy, and transmission electron microscope observations. Silicides, in the forms of SiOx and SiC, mainly exist in the shells of the nanocapsules and result in a large amount of defects at the 'core/shell' interfaces as well as in the shells. The complex permittivity and microwave absorption properties of the Ni/(C, silicides) nanocapsules are improved by the doped silicides. Compared with those of Ni/C nanocapsules, the positions of maximum absorption peaks of the Ni/(C, silicides) nanocapsules exhibit large red shifts. An electric dipole model is proposed to explain this red shift phenomenon.

  9. Light absorption properties of brown carbon in the high Himalayas

    NASA Astrophysics Data System (ADS)

    Kirillova, Elena N.; Marinoni, Angela; Bonasoni, Paolo; Vuillermoz, Elisa; Facchini, Maria Cristina; Fuzzi, Sandro; Decesari, Stefano

    2016-08-01

    The light-absorbing properties of water-soluble brown carbon (WS-BrC) and methanol-soluble brown carbon (MeS-BrC) were studied in PM10 aerosols collected at the "Nepal Climate Observatory-Pyramid" (NCO-P) station (5079 m above sea level) during the period 2013-2014. The light absorption coefficients of WS-BrC and MeS-BrC were the highest during the premonsoon season and the lowest during monsoon. MeS-BrC absorbs about 2 times higher at 365 nm and about 3 times more at 550 nm compared to WS-BrC. The mass absorption cross section (MAC) of WS-BrC measured at 365 nm is similar to that observed previously at South Asian low-altitude sites. Fractional solar radiation absorption by BrC compared to BC considering the full solar spectrum showed that WS-BrC absorbs 4 ± 1% and MeS-BrC absorbs 9 ± 2% compared to BC at NCO-P. Such ratios become 8 ± 1% (for WS-BrC respect to BC) and 17 ± 5% (for MeS-BrC respect to BC) when accounting for correction factors proposed by previous studies to convert absorption coefficients in bulk solutions into light absorption by accumulation mode aerosol particles. These results confirm the importance of BrC in contributing to light-absorbing aerosols in this region of the world. However, the BrC absorption at 550 nm appears small compared to that of BC (1-5%, or 3-9% with conversion factors), and it is lower compared to global model estimates constrained by Aerosol Robotic Network observations. Finally, our study provides no clear evidence of a change in the fractional contribution of BrC with respect to BC to light absorption in the middle troposphere respect to the Indo-Gangetic plain boundary layer.

  10. Properties of quasar broad absorption line outflows

    NASA Astrophysics Data System (ADS)

    Capellupo, Daniel Moshin

    2012-06-01

    Broad absorption lines (BALs) in quasar spectra identify high velocity outflows that likely exist in all quasars and could play a major role in feedback to galaxy evolution. In this dissertation, I use two methods to illuminate important properties of these outflows with the goal of a better understanding of these outflow systems and ultimately of the connection between quasars and their host galaxies. The variability of BALs can help us understand the structure, evolution, and basic physical properties of the outflows. I report here on a BAL monitoring programme of a sample of 24 luminous quasars at redshifts 1.2compare the variabilities in the C IV and Si IV lambda1400 absorption to try to ascertain the cause(s) of the variability. I find that Si IV BALs are more likely to vary than C IV BALs. When both C IV and Si IV varied, those changes always occurred in the same sense (either getting weaker or stronger). The multi-epoch data, including up to 10 epochs of data per quasar, show that the BAL changes were not generally monotonic across the full ˜5 to ˜8 yr time span of our observations, suggesting that the characteristic time-scale for significant line variations, and (perhaps) for structural changes in the outflows, is less than a few years. The evidence presented here indicates that the cause of variability is likely a complex mixture of changing ionization in the outflowing

  11. Absorption and fluorescence properties of fluorescein

    NASA Astrophysics Data System (ADS)

    Sjöback, Robert; Nygren, Jan; Kubista, Mikael

    1995-06-01

    We have characterized the protolytic equilibria of fluorescein and determined the spectroscopic properties of its protolytic forms. The protolytic constants relating the chemical activities (which at low ionic strength equal concentrations) of the cation, neutral form, anion and dianion are p K1 = 2.08, p K2 = 4.31, and p K3 = 6.43. All forms have rather high molar absorptivities being ɛ437FH 3 1 = 53 000, ɛ434FH 2 = 11 000, ɛ453FH- = 29 000 ( ɛ472FH = 29 000) and ɛ490F 2 = 76 900 M -1 cm -1 for the cation, neutral form, anion and dianion, respectively. The dianion has the most intense fluorescence with a quantum yield of 0.93 but also the anion shows considerable fluorescence with a quantum yield of 0.37. The neutral and cationic species are upon excitation converted into the anion and fluoresce with quantum yields of about 0.30 and 0.18, respectively.

  12. Scattering and Absorption Properties of Biomaterials for Dental Restorative Applications

    NASA Astrophysics Data System (ADS)

    Fernandez-Oliveras, A.; Rubiño, M.; Pérez, M. M.

    2013-08-01

    The physical understanding of the optical properties of dental biomaterials is mandatory for their final success in restorative applications.Light propagation in biological media is characterized by the absorption coefficient, the scattering coefficient, the scattering phase function,the refractive index, and the surface conditions (roughness). We have employed the inverse adding-doubling (IAD) method to combine transmittance and reflectance measurements performed using an integrating-sphere setup with the results of the previous scattering-anisotropygoniometric measurements. This has led to the determination of the absorption and the scattering coefficients. The aim was to optically characterize two different dental-resin composites (nanocomposite and hybrid) and one type of zirconia ceramic, and comparatively study them. The experimental procedure was conducted under repeatability conditions of measurement in order to determine the uncertainty associated to the optical properties of the biomaterials. Spectral variations of the refraction index and the scattering anisotropy factor were also considered. The whole experimental procedure fulfilled all the necessary requirements to provide optical-property values with lower associated uncertainties. The effective transport coefficient presented a similar spectral behavior for the two composites but completely different for the zirconia ceramic. The results demonstrated that the scattering anisotropy exerted a clearly distinct impact on the optical properties of the zirconia ceramic compared with those of the dental-resin composites.

  13. Spatial variability of absorption properties in Lake Balaton, Hungary

    NASA Astrophysics Data System (ADS)

    Riddick, C. A.; Hunter, P. D.; Tyler, A. N.; Vicente, V. M.; Groom, S.; Horváth, H.; Kovacs, A.; Preston, T.; Presing, M.

    2013-12-01

    In order to improve robustness of current remote sensing algorithms for lake monitoring, it is vital to understand the variability of inherent optical properties (IOPs) within a lake. In this study, absorption coefficients were measured in situ at 38 stations in Lake Balaton, Hungary, using a WET Labs AC-S and AC-9 and compared to concurrent absorption measurements by dual beam spectrophotometry in the laboratory. The spatial variability of bulk and chlorophyll-specific absorption coefficients was examined across 5 basins, demonstrating a gradient in total absorption corresponding to the trophic gradient. Our data suggests that sampling conditions had an impact on particulate absorption, affecting the proportion attributed to non-algal particles (aNAP), phytoplankton (aph) or color dissolved organic matter (aCDOM). The specific absorption of phytoplankton (a*ph) spectra showed a distinct peak in the UV portion of the spectra in Basins 3 and 4 (east), which may be due to the presence of phytoplankton photoprotective pigments to compensate for lower CDOM levels in these basins. In contrast to oceans, particulate attenuation (cp) had a weaker relationship to chlorophyll-a (R2=0.15) than to total suspended matter (R2=0.84), particularly the inorganic fraction. Additionally, the relative contribution of particulate scattering (bp) to attenuation was significantly higher in Lake Balaton (up to 85-99%) than that found in previous lacustrine studies. bp also demonstrated a gradient across the lake, where values increased as the water progressed from phytoplankton-dominated to mineral-dominated. These results provide knowledge of the heterogeneity of the IOPs within Lake Balaton, which is to be considered for the future improvement of bio-optical algorithms for constituent retrieval in inland waters.

  14. Iron absorption in humans: bovine serum albumin compared with beef muscle and egg white

    SciTech Connect

    Hurrell, R.F.; Lynch, S.R.; Trinidad, T.P.; Dassenko, S.A.; Cook, J.D.

    1988-01-01

    We studied the influence of bovine serum albumin and beef meat on nonheme iron absorption in humans and on dialyzable iron in vitro. The addition of serum albumin to a maize gruel had no significant effect on nonheme Fe absorption whereas the addition of beef meat caused a threefold increase. When added to a bread meal, serum albumin caused a modest 60% increase in nonheme Fe absorption and beef meat had no effect. When added to a protein-free meal, serum albumin reduced Fe absorption by 47% compared with a 72% reduction on addition of egg white. The bioavailability of nonheme Fe from meals containing serum albumin was consistently overestimated by the in vitro technique. We conclude that the facilitation of nonheme Fe absorption by meat is not a general property of all animal protein but is better explained by the action of one or more specific animal tissues.

  15. Electromagnetic absorption properties of graphene/Fe nanocomposites

    SciTech Connect

    Chen, Yujin; Lei, Zhenyu; Wu, Hongyu; Zhu, Chunling; Gao, Peng; Ouyang, Qiuyun; Qi, Li-Hong; Qin, Wei

    2013-09-01

    Graphical abstract: - Highlights: • Graphene/Fe nanocomposites were prepared by a facile and green method. • 10 nm Fe nanoparticles were uniformly dispersed over the surface of the graphene sheets. • The nanocomposites exhibited strong electromagnetic wave absorption properties. - Abstract: Graphene (G)/Fe nanocomposites with ferromagnetic properties at room temperature were fabricated by a facile and green method. Transmission electron microscope (TEM) and atomic force microscopy (AFM) amylases reveal that the α-Fe nanoparticles with a diameter of only about 10 nm were uniformly dispersed over the surface of the graphene sheets. Compared with other magnetic materials and the graphene, the nanocomposites exhibited significantly enhanced electromagnetic absorption properties. The maximum reflection loss to electromagnetic wave was up to −31.5 dB at a frequency of 14.2 GHz for G/Fe nanocomposites with a thickness of 2.5 mm. Importantly, the addition of the nanocomposites is only about 20 wt.% in the matrix. The enhanced mechanism is discussed and it is related to high surface areas of G/Fe nanocomposites, interfacial polarizations between graphene and iron, synergetic effect and efficient dispersity of magnetic NPs.

  16. Comparative nasal absorption of allergens in atopic and nonatopic subjects.

    PubMed

    Kontou-Karakitsos, K; Salvaggio, J E; Mathews, K P

    1975-04-01

    Based on sensitization following intranasal antigen administration, previous investigations have suggested greater absorption of allergens through the nasal mucous membranes of atopic than of nonatopic subjects. In this study mucosal absorption was assessed more directly by determining the capacity of allergens applied intranasally to elicit cutaneous Prausnitz-Küstner (P-K) reactions in nonatopic persons as compared with asymptomatic atopic subjects sensitive to other allergens. Two series of reaginic human serum dilutions were injected intracutaneously in recipients backs, and 48 hours later one series was challenged intracutaneously with test allergen. After the responses had been recorded, concentrated allergenic extract was sprayed into the nose and the second series of P-K sites observed for reactivity. Sometimes these P-K sites were rechallenged intracutaneously the following day to determine passive transfer neutralization. Two allergens were studied: bovine ribonuclease (RNase) and peanut extract. Two sera containing peanut reagins and one with RNase antibodies were each used in 10 to 11 atopic and 9 to 11 nonatopic recipients. The atopic group failed to show greater or more rapid absorption of either allergen through the nose based on the highest serum dilution reacting after nasal challenge. the speed of the reaction, the ratio of the titer by nasal challenge to the intracutaneous titer, or passive transfer neutralization. Controls showed that the results were not influenced by systemic absorption of allergen employed for intracutaneous tests. Drinking the amount of peanut extract applied intranasally did not elicit P-K reactions.

  17. Microwave absorption properties of composite powders with low density

    NASA Astrophysics Data System (ADS)

    Mu, Guohong; Shen, Haigen; Qiu, Jianxun; Gu, Mingyuan

    2006-12-01

    The composites of barium ferrite coated on hollow ceramic microspheres were prepared using sol-gel technique. The crystal structure, morphology and microwave absorption properties of composite powders with different weight ratio of microspheres were studied with XRD, EDS, FESEM and vector network analyzer. The results show that the microwave absorption properties of composite powders are greatly improved. The maximum microwave loss of composite powders reaches 31 dB with an amount of 50 wt.% microspheres, and its density is only about 1.80 g/cm 3. The effect of hollow ceramic microspheres on the microwave absorption property is also discussed.

  18. Stability properties of wines by absorption spectra

    NASA Astrophysics Data System (ADS)

    Larena, A.; Vega, J.

    1986-03-01

    The temporal evolution of absorption spectra (370-700 nm) of different spanish wines has been studied by us under the influence of air presence, and the light exposition. In particular, we have exposed the wines to a magenta light. Nevertheless, the color coordinates of wine show a little relative variation (0.1-1 %)

  19. Excellent microwave absorption property of Graphene-coated Fe nanocomposites

    PubMed Central

    Zhao, Xingchen; Zhang, Zhengming; Wang, Liaoyu; Xi, Kai; Cao, Qingqi; Wang, Dunhui; Yang, Yi; Du, Youwei

    2013-01-01

    Graphene has evoked extensive interests for its abundant physical properties and potential applications. It is reported that the interfacial electronic interaction between metal and graphene would give rise to charge transfer and change the electronic properties of graphene, leading to some novel electrical and magnetic properties in metal-graphene heterostructure. In addition, large specific surface area, low density and high chemical stability make graphene act as an ideal coating material. Taking full advantage of the aforementioned features of graphene, we synthesized graphene-coated Fe nanocomposites for the first time and investigated their microwave absorption properties. Due to the charge transfer at Fe-graphene interface in Fe/G, the nanocomposites show distinct dielectric properties, which result in excellent microwave absorption performance in a wide frequency range. This work provides a novel approach for exploring high-performance microwave absorption material as well as expands the application field of graphene-based materials. PMID:24305606

  20. Absorption properties of metal-semiconductor hybrid nanoparticles.

    PubMed

    Shaviv, Ehud; Schubert, Olaf; Alves-Santos, Marcelo; Goldoni, Guido; Di Felice, Rosa; Vallée, Fabrice; Del Fatti, Natalia; Banin, Uri; Sönnichsen, Carsten

    2011-06-28

    The optical response of hybrid metal-semiconductor nanoparticles exhibits different behaviors due to the proximity between the disparate materials. For some hybrid systems, such as CdS-Au matchstick-shaped hybrids, the particles essentially retain the optical properties of their original components, with minor changes. Other systems, such as CdSe-Au dumbbell-shaped nanoparticles, exhibit significant change in the optical properties due to strong coupling between the two materials. Here, we study the absorption of these hybrids by comparing experimental results with simulations using the discrete dipole approximation method (DDA) employing dielectric functions of the bare components as inputs. For CdS-Au nanoparticles, the DDA simulation provides insights on the gold tip shape and its interface with the semiconductor, information that is difficult to acquire by experimental means alone. Furthermore, the qualitative agreement between DDA simulations and experimental data for CdS-Au implies that most effects influencing the absorption of this hybrid system are well described by local dielectric functions obtained separately for bare gold and CdS nanoparticles. For dumbbell shaped CdSe-Au, we find a shortcoming of the electrodynamic model, as it does not predict the "washing out" of the optical features of the semiconductor and the metal observed experimentally. The difference between experiment and theory is ascribed to strong interaction of the metal and semiconductor excitations, which spectrally overlap in the CdSe case. The present study exemplifies the employment of theoretical approaches used to describe the optical properties of semiconductors and metal nanoparticles, to achieve better understanding of the behavior of metal-semiconductor hybrid nanoparticles.

  1. Spectral properties of molecular iodine in absorption cells filled to specified saturation pressure.

    PubMed

    Hrabina, Jan; Šarbort, Martin; Acef, Ouali; Burck, Frédéric Du; Chiodo, Nicola; Holá, Miroslava; Číp, Ondřej; Lazar, Josef

    2014-11-01

    We present the results of measurement and evaluation of spectral properties of iodine absorption cells filled at certain saturation pressure. A set of cells made of borosilicate glass instead of common fused silica was tested for their spectral properties in greater detail with special care for the long-term development of the absorption media purity. The results were compared with standard fused silica cells and the high quality of iodine was verified. A measurement method based on an approach relying on measurement of linewidth of the hyperfine transitions is proposed as a novel technique for iodine cell absorption media purity evaluation. A potential application in laser metrology of length is also discussed.

  2. Nanofluid optical property characterization: towards efficient direct absorption solar collectors.

    PubMed

    Taylor, Robert A; Phelan, Patrick E; Otanicar, Todd P; Adrian, Ronald; Prasher, Ravi

    2011-03-15

    Suspensions of nanoparticles (i.e., particles with diameters < 100 nm) in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 μm). A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ≥10 cm) with extremely low nanoparticle volume fractions - less than 1 × 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power) increase.

  3. Nanofluid optical property characterization: towards efficient direct absorption solar collectors

    PubMed Central

    2011-01-01

    Suspensions of nanoparticles (i.e., particles with diameters < 100 nm) in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 μm). A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ≥10 cm) with extremely low nanoparticle volume fractions - less than 1 × 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power) increase. PMID:21711750

  4. Thermal properties of carbon black aqueous nanofluids for solar absorption

    PubMed Central

    2011-01-01

    In this article, carbon black nanofluids were prepared by dispersing the pretreated carbon black powder into distilled water. The size and morphology of the nanoparticles were explored. The photothermal properties, optical properties, rheological behaviors, and thermal conductivities of the nanofluids were also investigated. The results showed that the nanofluids of high-volume fraction had better photothermal properties. Both carbon black powder and nanofluids had good absorption in the whole wavelength ranging from 200 to 2,500 nm. The nanofluids exhibited a shear thinning behavior. The shear viscosity increased with the increasing volume fraction and decreased with the increasing temperature at the same shear rate. The thermal conductivity of carbon black nanofluids increased with the increase of volume fraction and temperature. Carbon black nanofluids had good absorption ability of solar energy and can effectively enhance the solar absorption efficiency. PMID:21767359

  5. Interactions of praseodymium and neodymium with nucleosides and nucleotides: absorption difference and comparative absorption spectral study.

    PubMed

    Misra, S N; Anjaiah, K; Joseph, G; Abdi, S H

    1992-02-01

    The interactions of praseodymium(III) and neodymium(III) with nucleosides and nucleotides have been studied in different stoichiometry in water and water-DMF mixtures by employing absorption difference and comparative absorption spectrophotometry. The 4f-4f bands were analysed by linear curve analysis followed by gaussian curve analysis, and various spectral parameters were computed, using partial and multiple regression method. The magnitude of changes in both energy interaction and intensity were used to explore the degree of outer and inner sphere coordination, incidence of covalency and the extent of metal 4f-orbital involvement in chemical bonding. Crystalline complexes of the type [Ln(nucleotide)2(H2O)2]- (where nucleotide--GMP or IMP) were characterized by IR, 1H NMR, 31P NMR data. These studies indicated that the binding of the nucleotide is through phosphate oxygen in a bidentate manner and the complexes undergo substantial ionisation in aqueous medium, thereby supporting the observed weak 4f-4f bands and lower values for nephelauxetic effect (1-beta), bonding (b) and covalency (delta) parameters derived from coulombic and spin orbit interaction parameters.

  6. Absorption and emission properties of photonic crystals and metamaterials

    SciTech Connect

    Peng, Lili

    2007-01-01

    We study the emission and absorption properties of photonic crystals and metamaterials using Comsol Multiphysics and Ansoft HFSS as simulation tools. We calculate the emission properties of metallic designs using drude model and the results illustrate that an appropriate termination of the surface of the metallic structure can significantly increase the absorption and therefore the thermal emissivity. We investigate the spontaneous emission rate modifications that occur for emitters inside two-dimensional photonic crystals and find the isotropic and directional emissions with respect to different frequencies as we have expected.

  7. Absorption properties of waste matrix materials

    SciTech Connect

    Briggs, J.B.

    1997-06-01

    This paper very briefly discusses the need for studies of the limiting critical concentration of radioactive waste matrix materials. Calculated limiting critical concentration values for some common waste materials are listed. However, for systems containing large quantities of waste materials, differences up to 10% in calculated k{sub eff} values are obtained by changing cross section data sets. Therefore, experimental results are needed to compare with calculation results for resolving these differences and establishing realistic biases.

  8. The studies of high-frequency magnetic properties and absorption characteristics for amorphous-filler composites

    NASA Astrophysics Data System (ADS)

    Li, Z. W.; Yang, Z. H.

    2015-10-01

    Pure amorphous flake fillers and amorphous flakes coated by ferrite nanoparticles with core-shell-like structure were fabricated using mechanical ball-milling. The later with core-shell-like structure can greatly decrease permittivity and improve the absorption properties, as compared to the former. The absorption of all amorphous-filler composites has its origin in a quarter-wavelength resonator. Based on the resonator model, absorption frequency fA and the corresponding return loss RL are calculated, which are well consistent with observed values. It is also found that the resonance frequency is proportional to effective resistivity, based on William-Shockley-Kittel's eddy model.

  9. Microwave absorption properties of carbon nanocoils coated with highly controlled magnetic materials by atomic layer deposition.

    PubMed

    Wang, Guizhen; Gao, Zhe; Tang, Shiwei; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Lin, Shiwei; Feng, Yuhong; Zhou, Lei; Qin, Yong

    2012-12-21

    In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications.

  10. Spectral properties of microwave graphs with local absorption.

    PubMed

    Allgaier, Markus; Gehler, Stefan; Barkhofen, Sonja; Stöckmann, H-J; Kuhl, Ulrich

    2014-02-01

    The influence of absorption on the spectra of microwave graphs has been studied experimentally. The microwave networks were made up of coaxial cables and T junctions. First, absorption was introduced by attaching a 50Ω load to an additional vertex for graphs with and without time-reversal symmetry. The resulting level-spacing distributions were compared with a generalization of the Wigner surmise in the presence of open channels proposed recently by Poli et al. [Phys. Rev. Lett. 108, 174101 (2012)]. Good agreement was found using an effective coupling parameter. Second, absorption was introduced along one individual bond via a variable microwave attenuator, and the influence of absorption on the length spectrum was studied. The peak heights in the length spectra corresponding to orbits avoiding the absorber were found to be independent of the attenuation, whereas, the heights of the peaks belonging to orbits passing the absorber once or twice showed the expected decrease with increasing attenuation.

  11. Effect of water absorption on the mechanical properties of poly(3-hydroxybutyrate)/vegetable fiber composites

    NASA Astrophysics Data System (ADS)

    Marinho, Vithória A. D.; Carvalho, Laura H.; Canedo, Eduardo L.

    2015-05-01

    The present work studies the effect of water absorption on the performance of composites of poly(3-hydroxybutyrate) (PHB) - a fully biodegradable semi-crystalline thermoplastic obtained from renewable resources through low-impact biotechnological process, biocompatible and non-toxic - and vegetable fiber from the fruit (coconut) of babassu palm tree.Water resistance is an important characteristic of structural composites, that may exposed to rain and humid environments. Both water absorption capacity (water solubility in the material) and the rate of water absorption (controlled by the diffusivity of water in the material) are important parameters. However, water absorption per se may not be the most important characteristic, insofar as the performance and applications of the compounds. It is the effect of the water content on the ultimate properties that determine the suitability of the material for applications that involve prolonged exposure to water.PHB/babassu composites with 0-20% load were prepared in an internal mixer. Two different types of babassu fibers having two different article size ranges were compounded with PHB and test specimens molded by compression. The water absorption capacity and the kinetic constant of water absorption were measured in triplicate. Mechanical properties under tension were measured for dry and moist specimens with different amounts of absorbed water.Results indicate that the performance of the composites is comparable to that of the pure matrix. Water absorption capacity increases from 0.7% (pure PHB) to 4% (PHB/20% babassu), but the water diffusivity (4.10□8 cm2/s) was found to be virtually independent of the water absorption level. Water absorption results in moderate drop in elastic modulus (10-30% at saturation, according to fiber content) but has little effect on tensile strength and elongation at break. Fiber type and initial particle size do not have a significant effect on water absorption or mechanical properties.

  12. Optical absorption and scattering properties in the East China Sea

    NASA Astrophysics Data System (ADS)

    Zhang, Xuan; He, Xian-qiang; Chen, Xiao-yan; Hao, Zeng-zhou; Huang, Haiqing; Zhu, Qiankun

    2011-11-01

    The absorption and particulate backscattering coefficients are the basic parameters of the water inherent optical properties (IOPs), which are also the basic parameters for the development and validation of the semi-analysis models of the ocean color remote sensing. In this work, the absorption and backscattering coefficients in the East China Sea (ECS) were measured in the summer and winter of 2009 using the three in-situ optical instruments, including the WET Labs acs, and the HOBI Labs HydroScat-6. Based on the in-situ measured data, the distribution of the absorption and backscattering coefficients in the ECS are analyzed. The results show that in the summer the water absorption coefficient at 440nm (a(440nm),excluding the absorption of the pure sea water) in the surface layer is ranged from 0.022 to 0.067 m-1, and the particulate backscattering coefficient at 442nm(bbp(442nm), is between 0.00064 and 0.03274 m-1. As a whole, both of the absorption and backscattering coefficients decrease with the offshore direction, and the high values located at the mouth of Changjiang River. In the winter, a(440nm) is between 0.051 and 0.887 m-1, and bbp(442nm) is ranged from 0.000639 to 0.14614 m-1 at the surface layer. The spatial distributions in winter are similar as the summer, with the high value in the coast and low value in the offshore. The absorption and backscattering coefficients in winter are significantly larger than the summer's, especially in coastal area near the mouth of Changjiang River, which maybe caused by the southward Fujian-Zhejiang coastal current occurring in winter. As the vertical profile distributions, we find that both of the absorption and backscattering coefficients present a layer structure, which caused by the stratification of the sea water in the summer; while in the winter, affected by the strong wind disturbing, both of the absorption and backscattering coefficients are thoroughly vertical mixing. To our knowledge, it is the first time

  13. Mechanical properties and energy absorption characteristics of a polyurethane foam

    SciTech Connect

    Goods, S.H.; Neuschwanger, C.L.; Henderson, C.; Skala, D.M.

    1997-03-01

    Tension, compression and impact properties of a polyurethane encapsulant foam have been measured as a function of foam density. Significant differences in the behavior of the foam were observed depending on the mode of testing. Over the range of densities examined, both the modulus and the elastic collapse stress of the foam exhibited power-law dependencies with respect to density. The power-law relationship for the modulus was the same for both tension and compression testing and is explained in terms of the elastic compliance of the cellular structure of the foam using a simple geometric model. Euler buckling is used to rationalize the density dependence of the collapse stress. Neither tension nor compression testing yielded realistic measurements of energy absorption (toughness). In the former case, the energy absorption characteristics of the foam were severely limited due to the inherent lack of tensile ductility. In the latter case, the absence of a failure mechanism led to arbitrary measures of energy absorption that were not indicative of true material properties. Only impact testing revealed an intrinsic limitation in the toughness characteristics of the material with respect to foam density. The results suggest that dynamic testing should be used when assessing the shock mitigating qualities of a foam.

  14. Light absorption properties of laboratory-generated tar ball particles

    NASA Astrophysics Data System (ADS)

    Hoffer, A.; Tóth, A.; Nyirő-Kósa, I.; Pósfai, M.; Gelencsér, A.

    2016-01-01

    Tar balls (TBs) are a specific particle type that is abundant in the global troposphere, in particular in biomass smoke plumes. These particles belong to the family of atmospheric brown carbon (BrC), which can absorb light in the visible range of the solar spectrum. Albeit TBs are typically present as individual particles in biomass smoke plumes, their absorption properties have been only indirectly inferred from field observations or calculations based on their electron energy-loss spectra. This is because in biomass smoke TBs coexist with various other particle types (e.g., organic particles with inorganic inclusions and soot, the latter emitted mainly during flaming conditions) from which they cannot be physically separated; thus, a direct experimental determination of their absorption properties is not feasible. Very recently we have demonstrated that TBs can be generated in the laboratory from droplets of wood tar that resemble atmospheric TBs in all of their observed properties. As a follow-up study, we have installed on-line instruments to our laboratory set-up, which generate pure TB particles to measure the absorption and scattering, as well as the size distribution of the particles. In addition, samples were collected for transmission electron microscopy (TEM) and total carbon (TC) analysis. The effects of experimental parameters were also studied. The mass absorption coefficients of the laboratory-generated TBs were found to be in the range of 0.8-3.0 m2 g-1 at 550 nm, with absorption Ångström exponents (AAE) between 2.7 and 3.4 (average 2.9) in the wavelength range 467-652 nm. The refractive index of TBs as derived from Mie calculations was about 1.84 - 0.21i at 550 nm. In the brown carbon continuum, these values fall closer to those of soot than to other light-absorbing species such as humic-like substances (HULIS). Considering the abundance of TBs in biomass smoke and the global magnitude of biomass burning emissions, these findings may have

  15. Microwave absorption properties of graphite flakes-phenolic resin composite

    NASA Astrophysics Data System (ADS)

    Gogoi, Jyoti P.; Gogoi, Pragyan J.; Bhattacharyya, Nidhi S.

    2013-01-01

    In the present investigation, microwave absorption properties of a conductor back single layer designed on graphite flakes (GF)-novolac phenolic resin (NPR) composites is studied. The complex permittivity of the developed composite enhance for higher GF percentages. The reflection loss(RL) measured using E8362C VNA shows a maximum RL values -25 dB at 9.8 GHz for 7 wt. % composition with -10 dB bandwidth of 0.3 GHz. The developed composites are being light weight and cost effective shows potential to be used as dielectric absorber.

  16. Microwave absorption properties of carbon nanotubes dispersed in alumina ceramic

    NASA Astrophysics Data System (ADS)

    Chojnacki, E.; Huang, Q.; Mukherjee, A. K.; Holland, T. B.; Tigner, M.; Cherian, K.

    2011-12-01

    Ceramic nanocomposites of alumina and carbon nanotubes (CNTs) are experimentally studied for use as microwave absorbers in particle accelerators. The weight percentage of multi-walled CNTs in SPS sintered nanocomposite samples is varied from 0.5 to 10% and the complex permittivity is measured. The RF absorption is strong and relatively flat in the frequency band 1-40 GHz for a CNT weight percentage in the range 1-2.5%, which is just above the percolation threshold. The permittivity is observed to increase dramatically with increasing CNT weight percentage above the percolation threshold as observed elsewhere, and in accordance with theoretical treatments. The electromagnetic properties of the nanocomposites are little changed in going from 294 K to 77 K. The DC conductivity of the alumina-CNT nanocomposite is also sufficient to drain static charge in particle accelerator beamline environments, even at cryogenic temperatures. Fabrication of the nanocomposites using an industrial RF sintering process compatible with large sizes shows that the microwave absorption properties of small samples are similar to those of the SPS sintered samples.

  17. HAB detection based on absorption and backscattering properties of phytoplankton

    NASA Astrophysics Data System (ADS)

    Lei, Hui; Pan, Delu; Bai, Yan; Chen, Xiaoyan; Zhou, Yan; Zhu, Qiankun

    2011-11-01

    The coastal area of East China Sea (ECS) suffers from the harmful algal blooms (HAB) frequently every year in the warm season. The most common causative phytoplankton algal species of HAB in the ECS in recent years are Prorocentrum donghaiense (dinoflagellates), Karenia mikimotoi (dinoflagellates which could produce hemolytic and ichthyotoxins) and Skeletonema costatum (diatom). The discrimination between the dinoflagellates and diatom HAB through ocean color remote sensing approach can add the knowledge of HAB events in ECS and help to the precaution. A series of in-situ measurement consisted of absorption coefficient, total scattering and particulate backscattering coefficient was conducted in the southern coast of Zhejiang Province in May 2009, and the estuary of Changjiang River in August 2009 and December 2010, which encountered two HAB events and a moderate bloom. The Inherent Optical Properties (IOPs) of the bloom waters have significant difference between phytoplankton species in absorption and backscattering properties. The chlorophyll a specific absorption coefficient (a*phy(λ)) for the bloom patches (chlorophyll a concentration >6mg m-3) differ greatly from the adjacent normal seawater, with the a*phy(λ) of bloom water lower than 0.03 m2 mg-1 while the a*phy(λ) of the adjacent normal seawater is much higher (even up to 0.06 m2 mg-1). Meanwhile, the backscattering coefficients at 6 wavebands (420, 442, 470, 510, 590 and 700nm) are also remarkably lower for bloom waters (<0.01 m-1) than the normal seawater (> 0.02 m-1). The backscattering coefficient ratio (Rbp(λ)) is much lower for diatom bloom waters than for dinoflagellates types (0.01079 vs. 0.01227). A discrimination model based on IOPs is established, and several typical dinoflagellates and diatom bloom events including Prorocentrum donghaiense, Karenia mikimotoi and Skeletonema costatum in the ECS are picked out for testing with the MODIS-L2 and L3 ocean color remote sensing products from NASA

  18. Two-photon absorption in CdSe colloidal quantum dots compared to organic molecules.

    PubMed

    Makarov, Nikolay S; Lau, Pick Chung; Olson, Christopher; Velizhanin, Kirill A; Solntsev, Kyril M; Kieu, Khanh; Kilina, Svetlana; Tretiak, Sergei; Norwood, Robert A; Peyghambarian, Nasser; Perry, Joseph W

    2014-12-23

    We discuss fundamental differences in electronic structure as reflected in one- and two-photon absorption spectra of semiconductor quantum dots and organic molecules by performing systematic experimental and theoretical studies of the size-dependent spectra of colloidal quantum dots. Quantum-chemical and effective-mass calculations are used to model the one- and two-photon absorption spectra and compare them with the experimental results. Currently, quantum-chemical calculations are limited to only small-sized quantum dots (nanoclusters) but allow one to study various environmental effects on the optical spectra such as solvation and various surface functionalizations. The effective-mass calculations, on the other hand, are applicable to the larger-sized quantum dots and can, in general, explain the observed trends but are insensitive to solvent and ligand effects. Careful comparison of the experimental and theoretical results allows for quantifying the range of applicability of theoretical methods used in this work. Our study shows that the small clusters can be in principle described in a manner similar to that used for organic molecules. In addition, there are several important factors (quality of passivation, nature of the ligands, and intraband/interband transitions) affecting optical properties of the nanoclusters. The larger-size quantum dots, on the other hand, behave similarly to bulk semiconductors, and can be well described in terms of the effective-mass models. PMID:25427158

  19. Light absorption properties and radiative effects of primary organic aerosol emissions.

    PubMed

    Lu, Zifeng; Streets, David G; Winijkul, Ekbordin; Yan, Fang; Chen, Yanju; Bond, Tami C; Feng, Yan; Dubey, Manvendra K; Liu, Shang; Pinto, Joseph P; Carmichael, Gregory R

    2015-04-21

    Organic aerosols (OAs) in the atmosphere affect Earth's energy budget by not only scattering but also absorbing solar radiation due to the presence of the so-called "brown carbon" (BrC) component. However, the absorptivities of OAs are not represented or are poorly represented in current climate and chemical transport models. In this study, we provide a method to constrain the BrC absorptivity at the emission inventory level using recent laboratory and field observations. We review available measurements of the light-absorbing primary OA (POA), and quantify the wavelength-dependent imaginary refractive indices (kOA, the fundamental optical parameter determining the particle's absorptivity) and their uncertainties for the bulk POA emitted from biomass/biofuel, lignite, propane, and oil combustion sources. In particular, we parametrize the kOA of biomass/biofuel combustion sources as a function of the black carbon (BC)-to-OA ratio, indicating that the absorptive properties of POA depend strongly on burning conditions. The derived fuel-type-based kOA profiles are incorporated into a global carbonaceous aerosol emission inventory, and the integrated kOA values of sectoral and total POA emissions are presented. Results of a simple radiative transfer model show that the POA absorptivity warms the atmosphere significantly and leads to ∼27% reduction in the amount of the net global average POA cooling compared to results from the nonabsorbing assumption. PMID:25811601

  20. Light absorption properties and radiative effects of primary organic aerosol emissions.

    PubMed

    Lu, Zifeng; Streets, David G; Winijkul, Ekbordin; Yan, Fang; Chen, Yanju; Bond, Tami C; Feng, Yan; Dubey, Manvendra K; Liu, Shang; Pinto, Joseph P; Carmichael, Gregory R

    2015-04-21

    Organic aerosols (OAs) in the atmosphere affect Earth's energy budget by not only scattering but also absorbing solar radiation due to the presence of the so-called "brown carbon" (BrC) component. However, the absorptivities of OAs are not represented or are poorly represented in current climate and chemical transport models. In this study, we provide a method to constrain the BrC absorptivity at the emission inventory level using recent laboratory and field observations. We review available measurements of the light-absorbing primary OA (POA), and quantify the wavelength-dependent imaginary refractive indices (kOA, the fundamental optical parameter determining the particle's absorptivity) and their uncertainties for the bulk POA emitted from biomass/biofuel, lignite, propane, and oil combustion sources. In particular, we parametrize the kOA of biomass/biofuel combustion sources as a function of the black carbon (BC)-to-OA ratio, indicating that the absorptive properties of POA depend strongly on burning conditions. The derived fuel-type-based kOA profiles are incorporated into a global carbonaceous aerosol emission inventory, and the integrated kOA values of sectoral and total POA emissions are presented. Results of a simple radiative transfer model show that the POA absorptivity warms the atmosphere significantly and leads to ∼27% reduction in the amount of the net global average POA cooling compared to results from the nonabsorbing assumption.

  1. Optical absorption properties of dispersed gold and silver alloy nanoparticles.

    PubMed

    Wilcoxon, Jess

    2009-03-01

    The oldest topic in nanoscience is the size-dependent optical properties of gold and silver colloids or nanoparticles, first investigated scientifically by Michael Faraday in 1857. In the modern era, advances in both synthesis and characterization have resulted in new insights into the size-dependent absorbance of Au and Ag nanoparticles with sizes below the classical limit for Mie theory. In this paper we discuss the synthesis and properties of core/shell and nanoalloy particles of Au and Ag, compare them to particles of pure gold and silver, and discuss how alloying affects nanoparticle chemical stability. We show that composition, size, and nanostructure (e.g., core/shell vs quasi-random nanoalloy) can all be employed to adjust the optical absorbance properties. The type of nanostructure--core/shell vs alloy--is reflected in their optical absorbance features. PMID:19708105

  2. Optical absorption properties of dispersed gold and silver alloy nanoparticles.

    PubMed

    Wilcoxon, Jess

    2009-03-01

    The oldest topic in nanoscience is the size-dependent optical properties of gold and silver colloids or nanoparticles, first investigated scientifically by Michael Faraday in 1857. In the modern era, advances in both synthesis and characterization have resulted in new insights into the size-dependent absorbance of Au and Ag nanoparticles with sizes below the classical limit for Mie theory. In this paper we discuss the synthesis and properties of core/shell and nanoalloy particles of Au and Ag, compare them to particles of pure gold and silver, and discuss how alloying affects nanoparticle chemical stability. We show that composition, size, and nanostructure (e.g., core/shell vs quasi-random nanoalloy) can all be employed to adjust the optical absorbance properties. The type of nanostructure--core/shell vs alloy--is reflected in their optical absorbance features.

  3. Sound absorption by suspensions of nonspherical particles: measurements compared with predictions using various particle sizing techniques.

    PubMed

    Richards, Simon D; Leighton, Timothy G; Brown, Niven R

    2003-10-01

    Knowledge of the particle size distribution is required in order to predict ultrasonic absorption in polydisperse particulate suspensions. This paper shows that the method used to measure the particle size distribution can lead to important differences in the predicted absorption. A reverberation technique developed for measuring ultrasonic absorption by suspended particles is used to measure the absorption in suspensions of nonspherical particles. Two types of particulates are studied: (i) kaolin (china clay) particles which are platelike in form; and (ii) calcium carbonate particles which are more granular. Results are compared to theoretical predictions of visco-inertial absorption by suspensions of spherical particles. The particle size distributions, which are required for these predictions, are measured by laser diffraction, gravitational sedimentation and centrifugal sedimentation, all of which assume spherical particles. For a given sample, each sizing technique yields a different size distribution, leading to differences in the predicted absorption. The particle size distributions obtained by gravitational and centrifugal sedimentation are reinterpreted to yield a representative size distribution of oblate spheroids, and predictions for absorption by these spheroids are compared with the measurements. Good agreement between theory and measurement for the flat kaolin particles is obtained, demonstrating that these particles can be adequately represented by oblate spheroids. PMID:14587585

  4. Properties of Galaxies Detected in Emission and Absorption with Background Quasars

    NASA Astrophysics Data System (ADS)

    Straka, Lorrie Ann

    The question of how galaxies evolve is a difficult one to answer. By studying galaxies hosting Damped (DLA) and sub-Damped Lyman-alpha (sub-DLA) systems, we hope to shed some light on the subject. DLA and sub-DLA systems contain the vast majority of neutral gas in the universe, making them ideal candidates for studies of primordial gas. However, it is unclear how these absorption systems relate to present day galaxies. Observations of these systems detected through absorption in background quasar spectra indicate the DLAs are metal poor and slowly evolving while their counterparts, the sub-DLAs, are highly enriched. In order to determine the relationship between galaxies detected in absorption and normal galaxies, we compile a sample of low redshift quasar galaxy pairs (QGP) detected in emission in quasar spectra. These emission detected galaxies are searched for absorption features that may indicate a connection to higher redshift galaxy absorption systems, including DLAs and sub-DLAs. While the roles of spectroscopy and imaging play equal parts in determining characteristics of these systems, focus here is placed on the broad-band imaging aspect, used to locate absorption host galaxies and determine their photometric properties. These properties can then be compared to the known properties of galaxies at other epochs. The role of the Sloan Digital Sky Survey has been paramount in this study. Presented here are two sets of data: high metallicity DLA and sub-DLA absorption systems at z > 0.4 and quasar-galaxy pairs selected in emission from the Sloan Digital Sky Survey at z < 0.4. Results show that the z < 0.4 sample has low star formation rate values and a high degree of reddening which is in good agreement with higher redshift samples of quasar absorbers and our z > 0.4 sample of DLAs and sub-DLAs. Morphologically, those galaxies selected by emission naturally tend to be late-type, while our sample of DLAs and sub-DLAs appears to be primarily early-type.

  5. High-Frequency Absorption Properties of Three Kinds of Hollow Multiphase Ceramic Microspheres

    NASA Astrophysics Data System (ADS)

    Lou, Hongfei; Wang, Jianjiang; Hou, Yongshen; He, Ming; Zhao, Zhining

    2014-02-01

    Al-TiO2-Fe2O3-MnO2-Fe-Sucrose-Epoxy Resin as reaction system and self-reactive quenching technology which combines flame thermal spraying, self-propagating high-temperature synthesis and rapid solidification, were used to prepare three kinds of hollow multiphase ceramic microspheres (HMCMs) in different feeding gas (N2, O2) and dimension (coarse, fine). The characteristic results of three kinds of HMCMs indicated that various process parameters containing feeding gas and initial agglomerate size in this study can result in the change of surface organization, composition, morphology, and dimension. Investigation of microwave electromagnetic (EM) characteristics of three kinds of HMCMs showed that intrinsic characteristics play an important role in the determining the resulting properties. At 10-14.5 GHz, No. 3 HMCMs possess weak absorption intensity and narrow effective bandwidth (<-10 dB) owing to smaller dimension, but in higher-frequency band (14.5-17 GHz), an obvious absorption peak appears due to good EM match and nano-effects. Compared with No. 1 (O2 coarse) and No. 3 (O2 fine) HMCMs, enhanced absorption intensity and effective bandwidth (<-10 dB) were observed in No. 2 (N2 coarse) HMCMs. Enhancements of absorption intensity and effective bandwidth are associated with extra nitride (AlN, FeN), partial open microspheres, M-hexagonal crystal and micro-nano thick dendrite. No. 2 HMCMs presented excellent microwave-absorption property, with the minimum reflectivity ( R L) of -27.7 dB at 12.9 GHz. The effective bandwidth (<-10 dB) could reach to 4.1 GHz (10.9-15 GHz). This may be ascribed to the increased conductance loss, multiple scattering, magnetocrystalline anisotropy, and shape anisotropy.

  6. Comparative study of the intestinal absorption of three salts of calcium in young and elderly women.

    PubMed

    Praet, J P; Peretz, A; Mets, T; Rozenberg, S

    1998-04-01

    A daily ingestion of 1000 to 1500 mg elemental calcium associated with vitamin D supplement is presently considered to be the adequate and least expensive therapy for senile osteoporosis. There exists only scarce data about calcium absorption with available calcium salts in elderly patients. We have compared the digestive absorption of calcium (Ca) citrate in soluble and solid form and calcium gluconolactate-carbonate in 15 young and 20 elderly, healthy women using the oral calcium loading test. The subjects were divided into two groups. In the first group, the absorption of solid Ca citrate (1000 mg Ca element) was compared to the absorption of Ca gluconolactate-carbonate (1000 mg Ca element) both in young (n = 7) and elderly women (n = 10). In the second group, the absorption of soluble Ca citrate (1000 mg Ca element) was compared to the absorption of Ca gluconolactate-carbonate (1000 mg Ca element) in young (n = 8) and elderly (n = 10) women. In the preload phase, basal calciuria was increased in elderly women (p < 0.01) although basal calcemia was similar in young and elderly women. After oral administration of the calcium salts, an increase in plasma Ca was observed in both groups which was greater for soluble Ca citrate and Ca gluconolactate than for solid Ca citrate. In young women, the increase in plasma calcium was significantly higher with soluble Ca citrate compared to Ca gluconolactate (p < 0.05). In elderly women, the postload calciuria was significantly higher for soluble Ca citrate (p < 0.05) and Ca gluconolactate (p < 0.05) compared to solid Ca citrate. A similar pattern was observed in young women, although it was not significant. In conclusion, an oral load of 1000 mg soluble Ca citrate and Ca gluconolactate-carbonate induces significant biochemical changes suggesting a better digestive absorption compared to Ca citrate in solid form, both in young and elderly women. We did not observe different response, between young and old patients. PMID

  7. Optical nonlinear properties of InAs quantum dots by means of transient absorption measurements

    NASA Astrophysics Data System (ADS)

    Nakamura, H.; Nishikawa, S.; Kohmoto, S.; Kanamoto, K.; Asakawa, K.

    2003-07-01

    The optical nonlinear properties of self-assembled InAs/GaAs quantum dots (QDs) were experimentally verified by means of transient absorption measurements. A saturation pulse energy Ps of 13 fJ/μm2 and an absorption recovery time τr of 55 ps were obtained from transmission bleaching and pump/probe measurements for a waveguide sample with ten-layer-stacked QDs. An absorption saturation intensity Is of 2.5×104W/cm2, calculated from Ps and τr, was found. The saturation pulse energy is up to an order of magnitude smaller than, or at least comparable with, the reported values for excitons in quantum wells of III-V compound semiconductors. The dipole length, as calculated from the absorption cross section, is of the same order as the lattice constant of the InAs QDs. The results are expected to experimentally verify that QDs show a delta-function-like density of states.

  8. Preparation and Microwave Absorption Properties of Novel Carbon Nanofiber/Fe3O4 Composites.

    PubMed

    Ren, Yong; Dai, Bo; Wang, Gai-Hua; Zhang, Xiao-Wei; Zhu, Pei; Li, Shi-Rong

    2015-04-01

    Novel, carbonized bacterial cellulose (CBC)/Fe3O4 nanocomposites were synthesized using vacuum filtration and annealing (VFA) methods. The as-synthesized products were characterized by scanning electron microscopy, vibrating sample magnetometry, and transmission electron microscopy. The complex permittivity and permeability of Fe3O4-CBC (5 wt.% CBC)/paraffin wax composites were measured by vector network analysis. To study the microwave absorption (MA) performances, we compared the VFA products with the vacuum filtration (VF) products. The VFA products exhibited better absorption performances because of their larger dielectric loss. When the matching thickness was 2.4 mm, the calculated reflection loss reached a minimum value of -27 dB when VFA was used and a value of -11 dB when VF was used. The wide-range MA properties of these materials lead to potential applications in MA fields.

  9. Preparation and Microwave Absorption Properties of Novel Carbon Nanofiber/Fe3O4 Composites.

    PubMed

    Ren, Yong; Dai, Bo; Wang, Gai-Hua; Zhang, Xiao-Wei; Zhu, Pei; Li, Shi-Rong

    2015-04-01

    Novel, carbonized bacterial cellulose (CBC)/Fe3O4 nanocomposites were synthesized using vacuum filtration and annealing (VFA) methods. The as-synthesized products were characterized by scanning electron microscopy, vibrating sample magnetometry, and transmission electron microscopy. The complex permittivity and permeability of Fe3O4-CBC (5 wt.% CBC)/paraffin wax composites were measured by vector network analysis. To study the microwave absorption (MA) performances, we compared the VFA products with the vacuum filtration (VF) products. The VFA products exhibited better absorption performances because of their larger dielectric loss. When the matching thickness was 2.4 mm, the calculated reflection loss reached a minimum value of -27 dB when VFA was used and a value of -11 dB when VF was used. The wide-range MA properties of these materials lead to potential applications in MA fields. PMID:26353503

  10. Differences in spectral absorption properties between active neovascular macular degeneration and mild age related maculopathy.

    PubMed

    Balaskas, Konstantinos; Nourrit, Vincent; Dinsdale, Michelle; Henson, David B; Aslam, Tariq

    2013-05-01

    This study examines the differences in spectral absorption properties between the maculae of patients with active neovascular macular degeneration and those with early age related maculopathy (ARM). Patients attending for management of neovascular age related macular degeneration (AMD) underwent multispectral imaging with a system comprising of a modified digital fundus camera coupled with a 250-W tungsten-halogen lamp and a liquid crystal fast-tuneable filter. Images were obtained at 8 wavelengths between 496 and 700 nm. Aligned images were used to generate a DLA (differential light absorption, a measure of spectral absorption properties) map of the macular area. DLA maps were generated for both eyes of 10 sequential patients attending for anti-vascular endothelial growth factor injections. Each of these patients had active leaking neovascular AMD in one eye and early ARM or milder disease in the fellow eye. Eyes with neovascular AMD demonstrated lower average levels of DLA compared with their fellow eyes with early ARM (p=0.037, t test). The significant difference in DLA demonstrates the potential of multispectral imaging for differentiating the two pathologies non-invasively. PMID:23137662

  11. Microwave absorption properties of amorphous iron nanostructures fabricated by a high-yield method

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Zuo, Yalu; Yao, Yuelin; Xi, Li; Du, Jihong; Wang, Jianbo; Xue, Desheng

    2013-04-01

    Amorphous Fe nanoparticles and a nanonecklace were synthesized at room temperature by an aqueous reduction procedure, which provided a simple and potential method for volume production of ferromagnetic materials. The morphology was examined by scanning electron microscopy and transmission electron microscopy. The amorphism of Fe nanoparticles and the nanonecklace was confirmed by x-ray diffraction and electron diffraction patterns in transmission electron microscopy. The complex permittivity and permeability behaviour of amorphous iron nanoparticles/paraffin wax (NPPW) and nanonecklace/paraffin wax (NCPW) composites was investigated in 0.1-18 GHz by a coaxial method. The strongest reflection loss values of NPPW and NCPW calculated from permittivity and permeability reached -53.2 dB and -47.8 dB at 6.4 GHz and 4.6 GHz with matching thicknesses of 2.4 mm and 2.3 mm, respectively. Moreover, the frequency ranges of microwave absorption exceeding 90% were around 4.9-8.8 GHz and 3.7-6.1 GHz for NPPW and NCPW, respectively. Comparing the microwave absorption property with crystallized Fe nanostructures, we may conclude that the relatively high resistivity and low permittivity of amorphous Fe nanostructures are favourable for impedance matching, and consequently result in the attracting microwave absorption property of amorphous Fe nanostructures. Thus, amorphous iron nanoparticles and the nanonecklace prepared by a high-yield method have great potential to be a highly efficient microwave absorber.

  12. Microwave absorption properties of Mn- and Ni-doped zinc oxides

    SciTech Connect

    Wu Qibai; Zhao Wei; Zeng Guoxun; Zhang Haiyan; Wei Aixiang; Wang Jia

    2011-05-15

    Microwave absorption properties of Mn- and Ni-doped zinc oxides were assessed in this study. Samples were prepared by the decomposition of acetate solid solutions. By changing the concentration of dopant ions in the reaction solutions, zinc oxides with different amounts of dopant were obtained. The morphologies, chemical compositions, and structures of the samples were investigated by scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray powder diffraction. Electromagnetic characteristics of the doped samples were assessed by vector network analysis at a frequency range of 2-16 GHz. Both the real and imaginary parts of the complex permittivity decreased as Mn or Ni concentration increased. Results indicate that, compared with pure ZnO, Mn- and Ni-doped zinc oxides exhibit excellent microwave absorption properties. The highest level of microwave absorption observed was 80.7 dB at a frequency of 9.8 GHz, and the best frequency bandwidth was 8.6 GHz at reflection loss values below -10 dB.

  13. Curcumin-Loaded Lipid Cubic Liquid Crystalline Nanoparticles: Preparation, Optimization, Physicochemical Properties and Oral Absorption.

    PubMed

    He, Xiuli; Li, Qinghua; Liu, Xiuju; Wu, Guangsheng; Zhai, Guangxi

    2015-08-01

    In order to improve the oral absorption of curcumin, curcumin-loaded lipid cubic liquid crystalline nanoparticles were prepared and evaluated in vitro and in vivo. The hot and high-pressure homogenization method was used to prepare the nanoparticles. The formulation and process were optimized by uniform design with drug loading and entrapment efficiency as index, and physicochemical properties were also investigated. Spherical nanoparticles were observed under transmission electron microscope (TEM), with average particle size of 176.1 nm, zeta potential of -25.19 mV, average drug loading of (1.5 ± 0.2)% and entrapment efficiency of (95 ± 1.8)%. The in vitro release of curcumin from the nanoparticle formulation showed a sustained property, while the pharmacokinetics results after oral administration of curcumin loaded lipid cubic liquid crystalline nanoparticles in rat showed that the oral absorption of curcumin fitted one-compartment model and relative bioavailability was 395.56% when compared to crude curcumin. It can be concluded from these results that the lipid cubic liquid crystalline nanoparticles, as carriers, can markedly improve the oral absorption of curcumin.

  14. Synthesis, Characterization, and Microwave Absorption Property of the SnO2 Nanowire/Paraffin Composites

    NASA Astrophysics Data System (ADS)

    Feng, H. T.; Zhuo, R. F.; Chen, J. T.; Yan, D.; Feng, J. J.; Li, H. J.; Cheng, S.; Wu, Z. G.; Wang, J.; Yan, P. X.

    2009-12-01

    In this article, SnO2 nanowires (NWs) have been prepared and their microwave absorption properties have been investigated in detail. Complex permittivity and permeability of the SnO2 NWs/paraffin composites have been measured in a frequency range of 0.1-18 GHz, and the measured results are compared with that calculated from effective medium theory. The value of maximum reflection loss for the composites with 20 vol.% SnO2 NWs is approximately -32.5 dB at 14 GHz with a thickness of 5.0 mm.

  15. Ultraviolet absorption and luminescence properties of some cannabis constituents.

    PubMed

    Bowd, A; Byrom, P; Hudson, J B; Turnbull, J H

    1971-07-01

    The characteristics of the absorption, fluorescence and phosphorescence spectra of the cannabinols have been determined. The data provide a basis for the detection of these compounds at concentrations down to 10 ng ml .

  16. Solar Absorption by Aerosol-Bound Nitrophenols Compared to Aqueous and Gaseous Nitrophenols.

    PubMed

    Hinrichs, Ryan Z; Buczek, Pawel; Trivedi, Jal J

    2016-06-01

    Nitrophenols are well-known absorbers of near-UV/blue radiation and are considered to be a component of solar-absorbing organic aerosol material commonly labeled brown carbon. Nitrophenols have been identified in a variety of phases in earth's atmosphere, including the gaseous, aqueous, and aerosol bound, and these different environments alter their UV-vis absorption spectra, most dramatically when deprotonated forming nitrophenolates. We quantify the impact of these different absorption profiles by calculating the solar power absorbed per molecule for several nitrophenols. For instance, aqueous 2,4-dinitrophenol absorption varies dramatically over the pH range of cloud droplets with pH = 5.5 solutions absorbing three times the solar power compared to pH = 3.5 solutions. We also measured the UV-vis spectra of 2-nitrophenol adsorbed on several aerosol substrates representative of mineral dust, inorganic salts, and organic aerosol and compare these spectra to gaseous and aqueous 2-nitrophenol. 2-Nitrophenol adsorbed on mineral and chloride aerosol substrates exhibits a red-shifted absorption band (∼450-650 nm) consistent with 2-nitrophenolate and absorbs twice the solar power per molecule compared to gaseous, aqueous, and organic aerosol-bound 2-nitrophenol. We also discuss how different nitrophenol absorption profiles alter important atmospheric photolysis rate constants [e.g., J(NO2) and J(O3)] by attenuating solar flux.

  17. Moving-mesh cosmology: properties of neutral hydrogen in absorption

    NASA Astrophysics Data System (ADS)

    Bird, Simeon; Vogelsberger, Mark; Sijacki, Debora; Zaldarriaga, Matias; Springel, Volker; Hernquist, Lars

    2013-03-01

    We examine the distribution of neutral hydrogen in cosmological simulations carried out with the new moving-mesh code AREPO and compare it with the corresponding GADGET simulations based on the smoothed particle hydrodynamics (SPH) technique. The two codes use identical gravity solvers and baryonic physics implementations, but very different methods for solving the Euler equations, allowing us to assess how numerical effects associated with the hydro solver impact the results of simulations. Here we focus on an analysis of the neutral gas, as detected in quasar absorption lines. We find that the high column density regime probed by damped Lyα (DLA) and Lyman limit systems (LLS) exhibits significant differences between the codes. GADGET produces spurious artefacts in large haloes in the form of gaseous clumps, boosting the LLS cross-section. Furthermore, it forms haloes with denser central baryonic cores than AREPO, which leads to a substantially greater DLA cross-section from smaller haloes. AREPO thus produces a significantly lower cumulative abundance of DLAs, which is intriguingly in much closer agreement with observations. The column density function, however, is not altered enough to significantly reduce the discrepancy with the observed value. For the low column density gas probed by the Lyα forest, the codes differ only at the level of a few per cent, suggesting that this regime is quite well described by both methods, a fact that is reassuring for the many Lyα studies carried out with SPH thus far. While the residual differences are smaller than the errors on current Lyα forest data, we note that this will likely change for future precision experiments.

  18. Model parameterization to simulate and compare the PAR absorption potential of two competing plant species

    PubMed Central

    Silva, Brenner; Roos, Kristin; Göttlicher, Dietrich Otto; Rollenbeck, Rütger; Nauß, Thomas; Beck, Erwin

    2009-01-01

    Mountain pastures dominated by the pasture grass Setaria sphacelata in the Andes of southern Ecuador are heavily infested by southern bracken (Pteridium arachnoideum), a major problem for pasture management. Field observations suggest that bracken might outcompete the grass due to its competitive strength with regard to the absorption of photosynthetically active radiation (PAR). To understand the PAR absorption potential of both species, the aims of the current paper are to (1) parameterize a radiation scheme of a two-big-leaf model by deriving structural (LAI, leaf angle parameter) and optical (leaf albedo, transmittance) plant traits for average individuals from field surveys, (2) to initialize the properly parameterized radiation scheme with realistic global irradiation conditions of the Rio San Francisco Valley in the Andes of southern Ecuador, and (3) to compare the PAR absorption capabilities of both species under typical local weather conditions. Field data show that bracken reveals a slightly higher average leaf area index (LAI) and more horizontally oriented leaves in comparison to Setaria. Spectrometer measurements reveal that bracken and Setaria are characterized by a similar average leaf absorptance. Simulations with the average diurnal course of incoming solar radiation (1998–2005) and the mean leaf–sun geometry reveal that PAR absorption is fairly equal for both species. However, the comparison of typical clear and overcast days show that two parameters, (1) the relation of incoming diffuse and direct irradiance, and (2) the leaf–sun geometry play a major role for PAR absorption in the two-big-leaf approach: Under cloudy sky conditions (mainly diffuse irradiance), PAR absorption is slightly higher for Setaria while under clear sky conditions (mainly direct irradiance), the average bracken individual is characterized by a higher PAR absorption potential. (∼74 MJ m−2 year−1). The latter situation which occurs if the maximum daily

  19. Changes in Physical Property of Epoxy Resin with Absorption of Methyl Alcohol and Water

    NASA Astrophysics Data System (ADS)

    Wada, Ken; Nohara, Hiroshi; Shintani, Ryuichi

    1994-05-01

    Changes in physical properties with absorption of methyl alcohol and water were investigated. Upon CH3OH absorption, a boundary front appeared between the shell and core. The change in physical properties with absorption depended on the solvent and the volume absorbed. For example, when CH3OH of about 11 wt% was absorbed, Young's modulus decreased from 3.0×108 to 4.9×106 N/m2. In the case of H2O absorption (1 wt%), Young's modulus changed only slightly to 1.7×108 N/m2. The glass transition temperature T g shifted down to room temperature upon CH3OH absorption, but did not shift upon H2O absorption.

  20. Light scattering and absorption properties of aerosol particles in the urban environment of Granada, Spain

    NASA Astrophysics Data System (ADS)

    Lyamani, H.; Olmo, F. J.; Alados-Arboledas, L.

    convective boundary layer. Significant reduction in absorption coefficient values has been found during weekends compared to working days, showing a strong impact of local sources on aerosol properties. In contrast to σabs, the aerosol scattering coefficient obtained during weekends was higher than those obtained on Mondays and Tuesdays. A possible explanation for the large values of σsca measured during the weekend could be secondary aerosol aging.

  1. [Comparation of gastrointestinal absorption studies of specnuezhenide with salidroside in rats].

    PubMed

    Li, Hui-Fen; Zhang, Xue-Lan

    2014-03-01

    The experiment was designed to study the mechanism of increasing efficiency of Ligustrum lucidum steamed with wine. Rats in vivo with gastrointestinal perfusion model were used. The contents of salidroside and specnuezhenide in the fluid of gastrointestinal perfusion of rats were measured by HPLC at different time points after dosing. Then the K(a) and absorption percentage were calculated. Specnuezhenide could be detected in the fluid of gastrointestinal perfusion of specnuezhenide. The K(a) of the specnuezhenide and salidroside in the fetal intestines are 0.055 3 and 0.144 2 h(-1) respectively and the total absorptivity are 24.46% and 60.14% respectively after 4 hours. The K(a) in the stomach are 5.70 and 8.26 h(-1) respectively and the total absorptivity are 34.21% and 47.23% respectively after 4 hours. The experiment proved that specnuezhenide can be metabolized into salidroside which is more beneficial for gastrointestinal absorption. The experiment proved that specnuezhenide can be metabolized into salidroside both in the rat's stomach and the fetal intestine and compared with the specnuezhenide salidroside is more conducive to gastrointestinal absorption. The results suggested that the increasing efficiency on liver and kidney of L. lucidum steamed with wine has business with the fact that Specnuezhe nide is more conducive to the body after it is changed into salidroside. PMID:24956860

  2. Ripeness of 'Sun Bright' tomato using the optical absorption and scattering properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maturity is one of the most important factors in determining the processing and eating quality of tomato. The objective of this research was to test the suitability of optical absorption and scattering properties for evaluating the maturity of tomatoes. Optical absorption and reduced scattering coef...

  3. Near-infrared diode laser based spectroscopic detection of ammonia: a comparative study of photoacoustic and direct optical absorption methods

    NASA Technical Reports Server (NTRS)

    Bozoki, Zoltan; Mohacsi, Arpad; Szabo, Gabor; Bor, Zsolt; Erdelyi, Miklos; Chen, Weidong; Tittel, Frank K.

    2002-01-01

    A photoacoustic spectroscopic (PAS) and a direct optical absorption spectroscopic (OAS) gas sensor, both using continuous-wave room-temperature diode lasers operating at 1531.8 nm, were compared on the basis of ammonia detection. Excellent linear correlation between the detector signals of the two systems was found. Although the physical properties and the mode of operation of both sensors were significantly different, their performances were found to be remarkably similar, with a sub-ppm level minimum detectable concentration of ammonia and a fast response time in the range of a few minutes.

  4. Comparing Spatial Distributions of Solar Prominence Mass Derived from Coronal Absorption

    NASA Technical Reports Server (NTRS)

    Gilbert, Holly; Kilper, Gary; Alexander, David; Kucera, Therese

    2010-01-01

    In the present work we extend the use of this mass-inference technique to a sample of prominences observed in at least two coronal lines. This approach, in theory, allows a direct calculation of prominence mass and helium abundance and how these properties vary spatially and temporally. Our motivation is two-fold: to obtain a He(exp 0)/H(exp 0) abundance ratio, and to determine how the relative spatial distribution of the two species varies in prominences. The first of these relies on the theoretical expectation that the amount of absorption at each EUV wavelength is well-characterized. However, in this work we show that due to a saturation of the continuum absorption in the 625 A and 368 A lines (which have much higher opacity compared to 195 A-) the uncertainties in obtaining the relative abundances are too high to give meaningful estimates. This is an important finding because of its impact on future studies in this area. The comparison of the spatial distribution of helium and hydrogen presented here augments previous observational work indicating that cross-field diffusion of neutrals is an important mechanism for mass loss. Significantly different loss timescales for neutral He and H (helium drains much more rapidly than hydrogen) can impact prominence structure, and both the present and past studies suggest this mechanism is playing a role in structure and possibly dynamics. Section 2 of this paper contains a description of the observations and Section 3 summarizes the method used to infer mass along with the criteria imposed in choosing prominences appropriate for this study. Section 3 also contains a discussion of the problems due to limitations of the available data and the implications for determining relative abundances. We present our results in Section 4, including plots of radial-like scans of prominence mass in different lines to show the spatial distribution of the different species. The last section contains a discussion summarizing the importance

  5. Metal-free carbon nanotubes: synthesis, and enhanced intrinsic microwave absorption properties

    PubMed Central

    Qi, Xiaosi; Xu, Jianle; Hu, Qi; Deng, Yu; Xie, Ren; Jiang, Yang; Zhong, Wei; Du, Youwei

    2016-01-01

    In order to clearly understand the intrinsic microwave absorption properties of carbon nanomaterials, we proposed an efficient strategy to synthesize high purity metal-free carbon nanotubes (CNTs) over water-soluble K2CO3 particles through chemical vapor decomposition and water-washing process. The comparison results indicated the leftover catalyst caused negative effects in intrinsic microwave absorption properties of CNTs, while an enhanced microwave absorption performance could be observed over the metal-free CNT sample. Moreover, the results indicated that the microwave absorption properties could be tuned by the CNT content. Therefore, we provided a simple route to investigate the intrinsic properties of CNTs and a possible enhanced microwave absorbing mechanism. PMID:27324290

  6. Metal-free carbon nanotubes: synthesis, and enhanced intrinsic microwave absorption properties.

    PubMed

    Qi, Xiaosi; Xu, Jianle; Hu, Qi; Deng, Yu; Xie, Ren; Jiang, Yang; Zhong, Wei; Du, Youwei

    2016-01-01

    In order to clearly understand the intrinsic microwave absorption properties of carbon nanomaterials, we proposed an efficient strategy to synthesize high purity metal-free carbon nanotubes (CNTs) over water-soluble K2CO3 particles through chemical vapor decomposition and water-washing process. The comparison results indicated the leftover catalyst caused negative effects in intrinsic microwave absorption properties of CNTs, while an enhanced microwave absorption performance could be observed over the metal-free CNT sample. Moreover, the results indicated that the microwave absorption properties could be tuned by the CNT content. Therefore, we provided a simple route to investigate the intrinsic properties of CNTs and a possible enhanced microwave absorbing mechanism.

  7. Metal-free carbon nanotubes: synthesis, and enhanced intrinsic microwave absorption properties

    NASA Astrophysics Data System (ADS)

    Qi, Xiaosi; Xu, Jianle; Hu, Qi; Deng, Yu; Xie, Ren; Jiang, Yang; Zhong, Wei; Du, Youwei

    2016-06-01

    In order to clearly understand the intrinsic microwave absorption properties of carbon nanomaterials, we proposed an efficient strategy to synthesize high purity metal-free carbon nanotubes (CNTs) over water-soluble K2CO3 particles through chemical vapor decomposition and water-washing process. The comparison results indicated the leftover catalyst caused negative effects in intrinsic microwave absorption properties of CNTs, while an enhanced microwave absorption performance could be observed over the metal-free CNT sample. Moreover, the results indicated that the microwave absorption properties could be tuned by the CNT content. Therefore, we provided a simple route to investigate the intrinsic properties of CNTs and a possible enhanced microwave absorbing mechanism.

  8. The tunable electronic structure and optic absorption properties of phosphorene by a normally applied electric field

    NASA Astrophysics Data System (ADS)

    Yang, Mou; Duan, Hou-Jian; Wang, Rui-Qiang

    2016-10-01

    We studied the electronic structure and optical absorption properties of phosphorene (a monolayer black phosphorus) under a normally applied electric field. The electric field enlarges the energy gap, weakens the effective mass anisotropy, and increases the effective mass component along the armchair direction (x-direction) for both conduction and valence bands but provides little change to the component along the zigzag direction (y-direction). The band edge optical absorption is completely polarized in the x-direction, and decreases when increasing the electric field. If the exciting frequency is beyond the energy gap, the absorption for the y-polarized light becomes nonzero, but the absorption is still highly polarized.

  9. Rest-frame optical properties of luminous, radio-selected broad absorption line quasars

    NASA Astrophysics Data System (ADS)

    Runnoe, Jessie C.; Ganguly, R.; Brotherton, M. S.; DiPompeo, M. A.

    2013-08-01

    We have obtained Infrared Telescope Facility/SpeX spectra of eight moderate-redshift (z = 0.7-2.4), radio-selected (log R* ≈ 0.4-1.9) broad absorption line (BAL) quasars. The spectra cover the rest-frame optical band. We compare the optical properties of these quasars to those of canonically radio-quiet (log R* ≲ 1) BAL quasars at similar redshifts and to low-redshift quasars from the Palomar-Green catalogue. As with previous studies of BAL quasars, we find that [O III] λ5007 is weak, and optical Fe II emission is strong, a rare combination in canonically radio-loud (log R* ≳ 1) quasars. With our measurements of the optical properties, particularly the Balmer emission-line widths and the continuum luminosity, we have used empirical scaling relations to estimate black hole masses and Eddington ratios. These lie in the range (0.4-2.6) × 109 M⊙ and 0.1-0.9, respectively. Despite their comparatively extreme radio properties relative to most BAL quasars, their optical properties are quite consistent with those of radio-quiet BAL quasars and dissimilar to those of radio-loud non-BAL quasars. While BAL quasars generally appear to have low values of [O III] λ5007/Fe II an extreme of `Eigenvector 1', the Balmer line widths and Eddington ratios do not appear to significantly differ from those of unabsorbed quasars at similar redshifts and luminosities.

  10. Absorption measurement of thin films by using photothermal techniques: The influence of thermal properties

    SciTech Connect

    Wu, Z.L.; Kuo, P.K.; Thomas, R.L.; Fan, Z.X.

    1995-12-31

    Photothermal techniques are widely used for measuring optical absorption of thin film coatings. In these applications the calibration of photothermal signal is typically based on the assumption that the thermal properties of the thin film make very little contribution. In this paper we take mirage technique as an example and present a detailed analysis of the influence of thin film thermal properties on absorption measurements. The results show that the traditional calibration method is not valid on surprisingly many situations.

  11. Nonlinear absorption and transmission properties of Ge, Te and InAs using tuneable IR FEL

    SciTech Connect

    Amirmadhi, F.; Becker, K.; Brau, C.A.

    1995-12-31

    Nonlinear absorption properties of Ge, Te and InAs are being investigated using the transmission of FEL optical pulses through these semiconductors (z-scan method). Wavelength, intensity and macropulse dependence are used to differentiate between two-photon and free-carrier absorption properties of these materials. Macropulse dependence is resolved by using a Pockles Cell to chop the 4-{mu}s macropulse down to 100 ns. Results of these experiments will be presented and discussed.

  12. Electromagnetic wave absorption properties of composites with ultrafine hollow magnetic fibers

    NASA Astrophysics Data System (ADS)

    Yi, Jin Woo; Lee, Sang Bok; Kim, Jin Bong; Lee, Sang Kwan; Park, O. Ok

    2014-06-01

    Ultrafine hollow magnetic fibers were prepared by electroless plating using hydrolyzed polyester fiber as a sacrificial substrate. These hollow fibers can be served for lightweight and efficient electromagnetic (EM) absorbing materials. As observed from SEM and EDS analysis, hollow structures consisting of Ni inner layer and Fe or Fe-Co outer layer were obtained. By introducing Co onto Fe, oxidation of the Fe layer was successfully prevented making it possible to enhance the complex permeability compared to a case in which only Fe was used. Polymeric composites containing the hollow fibers with different weight fractions and fiber lengths were prepared by a simple mixing process. The electromagnetic wave properties of the composites were measured by a vector network analyzer and it was found that the hollow magnetic fibers show a clear resonance peak of the complex permittivity around the X-band range (8-12 GHz) and the resonance frequency strongly depends on the fiber concentration and length. A possible explanation for the unique resonance is that the hollow fibers possess relatively low electrical conductivity and a long mean free path due to their oxidized phase and hollow structure. The calculated EM wave absorption with the measured EM wave properties showed that the composite containing 30 wt% hollow Ni/Fe-Co (7:3) fibers in length of 180 μm exhibited multiple absorbance peaks resulting in a broad absorption bandwidth of 4.2 GHz. It is obvious that this multiple absorbance is attributed to the resonance characteristic of the composite.

  13. Investigating cloud absorption effects: Global absorption properties of black carbon, tar balls, and soil dust in clouds and aerosols

    NASA Astrophysics Data System (ADS)

    Jacobson, Mark Z.

    2012-03-01

    This study examines modeled properties of black carbon (BC), tar ball (TB), and soil dust (SD) absorption within clouds and aerosols to understand better Cloud Absorption Effects I and II, which are defined as the effects on cloud heating of absorbing inclusions in hydrometeor particles and of absorbing aerosol particles interstitially between hydrometeor particles at their actual relative humidity (RH), respectively. The globally and annually averaged modeled 550 nm aerosol mass absorption coefficient (AMAC) of externally mixed BC was 6.72 (6.3-7.3) m2/g, within the laboratory range (6.3-8.7 m2/g). The global AMAC of internally mixed (IM) BC was 16.2 (13.9-18.2) m2/g, less than the measured maximum at 100% RH (23 m2/g). The resulting AMAC amplification factor due to internal mixing was 2.41 (2-2.9), with highest values in high RH regions. The global 650 nm hydrometeor mass absorption coefficient (HMAC) due to BC inclusions was 17.7 (10.6-19) m2/g, ˜9.3% higher than that of the IM-AMAC. The 650 nm HMACs of TBs and SD were half and 1/190th, respectively, that of BC. Modeled aerosol absorption optical depths were consistent with data. In column tests, BC inclusions in low and mid clouds (CAE I) gave column-integrated BC heating rates ˜200% and 235%, respectively, those of interstitial BC at the actual cloud RH (CAE II), which itself gave heating rates ˜120% and ˜130%, respectively, those of interstitial BC at the clear-sky RH. Globally, cloud optical depth increased then decreased with increasing aerosol optical depth, consistent with boomerang curves from satellite studies. Thus, CAEs, which are largely ignored, heat clouds significantly.

  14. Characterization of Spectral Absorption Properties of Aerosols Using Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.; Ahn, C.

    2012-01-01

    The wavelength-dependence of aerosol absorption optical depth (AAOD) is generally represented in terms of the Angstrom Absorption Exponent (AAE), a parameter that describes the dependence of AAOD with wavelength. The AAE parameter is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses high spectral resolution measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measured reflectance (rho lambda) is approximately given by Beer's law rho lambda = rho (sub 0 lambda) e (exp -mtau (sub abs lambda)) where rho(sub 0 lambda) is the cloud reflectance, m is the geometric slant path and tau (sub abs lambda) is the spectral AAOD. The rho (sub 0 lambda) term is determined by means of radiative transfer calculations using as input the cloud optical depth derived as described in Torres et al. [JAS, 2012] that accounts for the effects of aerosol absorption. In the second step, corrections for molecular and aerosol scattering effects are applied to the cloud reflectance term, and the spectral AAOD is then derived by inverting the equation above. The proposed technique will be discussed in detail and application results will be presented. The technique can be easily applied to hyper-spectral satellite measurements that include UV such as OMI, GOME and SCIAMACHY, or to multi-spectral visible measurements by other sensors provided that the aerosol-above-cloud events are easily identified.

  15. Retrieval of Aerosol Absorption Properties from Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Bhartia, Pawan K.; Jethva, H.; Ahn, Chang-Woo

    2012-01-01

    The Angstrom Absorption Exponent (AAE) is a parameter commonly used to characterize the wavelength-dependence of aerosol absorption optical depth (AAOD). It is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses multi-spectral measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measurement can be explained, using an approximations of Beer's Law (BL), as the upwelling reflectance at the cloud top attenuated by the absorption effects of the overlying aerosol layer. The upwelling reflectance at the cloud-top in an aerosol-free atmospheric column is mainly a function of cloud optical depth (COD). In the proposed method of AAE derivation, the first step is determining COD which is retrieved using a previously developed color-ratio based approach. In the second step, corrections for molecular scattering effects are applied to both the observed ad the calculated cloud reflectance terms, and the spectral AAOD is then derived by an inversion of the BL approximation. The proposed technique will be discussed in detail and application results making use of OMI multi-spectral measurements in the UV-Vis. will be presented.

  16. Transient Infrared Measurement of Laser Absorption Properties of Porous Materials

    NASA Astrophysics Data System (ADS)

    Marynowicz, Andrzej

    2016-06-01

    The infrared thermography measurements of porous building materials have become more frequent in recent years. Many accompanying techniques for the thermal field generation have been developed, including one based on laser radiation. This work presents a simple optimization technique for estimation of the laser beam absorption for selected porous building materials, namely clinker brick and cement mortar. The transient temperature measurements were performed with the use of infrared camera during laser-induced heating-up of the samples' surfaces. As the results, the absorbed fractions of the incident laser beam together with its shape parameter are reported.

  17. A Parallel Reconstruction Scheme in Fluorescence Tomography Based on Contrast of Independent Inversed Absorption Properties

    PubMed Central

    Yi, Ji; Bai, Jing

    2006-01-01

    Based on an independent forward model in fluorescent tomography, a parallel reconstructed scheme for inhomogeneous mediums with unknown absorption property is proposed in this paper. The method considers the two diffusion equations as separately describing the propagation of excited light in tissues with and without fluorescent probes inside. Then the concentration of fluorophores is obtained directly through the difference between two estimations of absorption coefficient which can be parallel inversed. In this way, the multiparameter estimation problem in fluorescent tomography is transformed into two independent single-coefficient determined schemes of diffusion optical tomography (DOT). Any algorithms proved to be efficient and effective in DOT can be directly applied here. In this study the absorption property is estimated from the independent diffusion equations by a gradient-based optimization method with finite element method (FEM) solving the forward model. Simulation results of three representative occasions show that the reconstructed method can well estimate fluorescent property and tissue absorption distribution. PMID:23165045

  18. Comparative properties of feline coronaviruses in vitro.

    PubMed

    McKeirnan, A J; Evermann, J F; Davis, E V; Ott, R L

    1987-04-01

    Two feline coronaviruses were characterized to determine their biological properties in vitro and their antigenic relatedness to a previously recognized feline infectious peritonitis virus and canine coronavirus. The viruses, designated WSU 79-1146 and WSU 79-1683, were shown to have comparable growth curves with the prototype feline infectious peritonitis virus. Treatment of the feline infectious peritonitis virus strains with 0.25% trypsin indicated that they were relatively resistant to proteolytic inactivation when compared with the feline enteric coronavirus strain. This observation may serve as a useful in vitro marker to distinguish closely related members of the feline coronavirus group. Plaque assay results indicated that the feline infectious peritonitis virus strains produced large homogeneous plaques in comparison to the feline enteric coronavirus strain and canine coronavirus, which showed a heterogenous plaque size distribution. No naturally temperature sensitive mutants were detected in either of the feline coronavirus populations. Both of the viruses were antigenically related to feline infectious peritonitis virus and to a lesser extent to canine coronavirus by virus neutralization.

  19. Enhanced Microwave Absorption Properties of Carbon Black/Silicone Rubber Coating by Frequency-Selective Surface

    NASA Astrophysics Data System (ADS)

    Yang, Zhaoning; Luo, Fa; Gao, Lu; Qing, Yuchang; Zhou, Wancheng; Zhu, Dongmei

    2016-10-01

    A square frequency-selective surface (FSS) design has been employed to improve the microwave absorption properties of carbon black/silicone rubber (CBSR) composite coating. The FSS is placed on the surface of the CBSR coating. The effects of FSS design parameters on the microwave absorption properties of the CBSR coating have been investigated, including the size and period of the FSS design, and the thickness and permittivity of the coating. Simulation results indicate that the absorption peak for the CBSR coating alone is related to its thickness and electromagnetic parameters, while the combination of the CBSR coating with a FSS can exhibit a new absorption peak in the reflection curve; the frequency of the new absorption peak is determined by the resonance of the square FSS design and tightly depends on the size of the squares, with larger squares in the FSS design leading to a lower frequency of the new absorption peak. The enhancement of the absorption performance depends on achievement of a new absorption peak using a suitable size and period of the FSS design. In addition, the FSS design has a stable frequency response for both transverse electromagnetic (TE) and transverse magnetic (TM) polarizations as the incident angle varies from 0° to 40°. The optimized results indicate that the bandwidth with reflection loss below -5 dB can encompass the whole frequency range from 8 GHz to 18 GHz for thickness of the CBSR coating of only 1.8 mm. The simulation results are confirmed by experiments.

  20. Relationships between absorption efficiency of elements in mammals and chemical properties.

    PubMed

    Le, T T Yen; Hendriks, A Jan

    2013-10-01

    Oral absorption efficiency is an important factor to consider in human risk assessment and varies widely between elements. Linking absorption efficiency to chemical properties facilitates the understanding of underlying processes and enables extrapolation across elements. In our study, oral absorption efficiency in humans was predicted for a number of elements based on their ionization energy and electronegativity. Data on oral absorption efficiency in humans were retrieved via a literature survey. A model was developed based on the assumption that ionic species readily react with biotic ligands. Accordingly, ionization energy was presumed to represent the reactivity and absorption of atoms in the gastrointestinal tract. The coefficients of the model were parameterized by fitting the quantitative relationship between absorption efficiency and ionization energy to data collected from well-standardized studies. Generally, absorption efficiency was strongly related to ionization energy, explaining 94% of the variability in absorption efficiency between elements reported by the International Commission on Radiological Protection (ICRP). In addition, the absorption efficiencies predicted based on ionization energy were within a factor of two of those given by the ICRP (ME = -0.05; RMSE = 0.31). However, the model is not applicable to alkaline metals and molybdenum because of the uniquely high solubility of their compounds or the flexible electron configuration of these elements. Approximately 56% of the variability in absorption efficiency between elements could be explained by electronegativity. These strong relationships between absorption efficiency and ionization energy and, to a lesser extent, electronegativity indicate potential for extrapolation across elements using atomic properties.

  1. Comparative accuracy of the Albedo, transmission and absorption for selected radiative transfer approximations

    NASA Technical Reports Server (NTRS)

    King, M. D.; HARSHVARDHAN

    1986-01-01

    Illustrations of both the relative and absolute accuracy of eight different radiative transfer approximations as a function of optical thickness, solar zenith angle and single scattering albedo are given. Computational results for the plane albedo, total transmission and fractional absorption were obtained for plane-parallel atmospheres composed of cloud particles. These computations, which were obtained using the doubling method, are compared with comparable results obtained using selected radiative transfer approximations. Comparisons were made between asymptotic theory for thick layers and the following widely used two stream approximations: Coakley-Chylek's models 1 and 2, Meador-Weaver, Eddington, delta-Eddington, PIFM and delta-discrete ordinates.

  2. A joint model for the emission and absorption properties of damped Lyα absorption systems

    NASA Astrophysics Data System (ADS)

    Barnes, Luke A.; Haehnelt, Martin G.

    2009-07-01

    The recently discovered population of ultra-faint extended line emitters, with fluxes of a few times 10-18ergs-1cm-2 at z ~ 3, can account for the majority of the incidence rate of damped Lyα systems (DLAs) at this redshift if the line emission is interpreted as Lyα. We show here that a model similar to that proposed by Haehnelt, Steinmetz & Rauch (2000), which reproduces the incidence rate and kinematics of DLAs in the context of Λ cold dark matter models for structure formation, also reproduces the size distribution of the new population of faint Lyα emitters for plausible parameters. This lends further support to the interpretation of the emission as Lyα, as well as the identification of the emitters with the hitherto elusive population of DLA host galaxies. The observed incidence rate of DLAs together with the observed space density and size distribution of the emitters suggest a duty cycle of ~0.2-0.4 for the Lyα emission from DLA host galaxies. We further show that Lyα cooling is expected to contribute little to the Lyα emission for the majority of emitters. This leaves centrally concentrated star formation at a rate of a few tenths Msolaryr-1, surrounded by extended Lyα haloes with radii up to 30-50 kpc, as the most plausible explanation for the origin of the emission. Both the luminosity function of Lyα emission and the velocity width distribution of low ionization absorption require that galaxies inside dark matter (DM) haloes with virial velocities <~50-70kms-1 contribute little to the incidence rate of DLAs at z ~ 3, suggesting that energy and momentum input due to star formation efficiently removes gas from these haloes. Galaxies with DM haloes with virial velocities of 100-150kms-1 appear to account for the majority of DLA host galaxies. DLA host galaxies at z ~ 3 should thus become the building blocks of typical present-day galaxies like our Milky Way.

  3. Intestinal absorption of calcium from foodstuffs as compared to a pharmaceutical preparation.

    PubMed

    Werner, E; Hansen, Ch; Roth, P; Kaltwasser, J P

    1999-01-01

    Only few data are available on intestinal calcium absorption from foodstuffs and composite meals in humans. The aim of the study was to compare intraindividually the calcium absorption from milk and from a breakfast with that from a pharmaceutical calcium preparation of equal calcium content. In 8 healthy volunteers between 44 and 58 years of age, the intestinal calcium absorption was measured in randomized order applying the double isotope technique from: (1) 500ml of fresh milk (equivalent to 620mg Ca), (2) a test meal composed of 250 g curd, 150g yoghurt, 3 slices pineapple, 2 breakfast rolls, 2 cups of coffee, 10g of coffee cream, 20g butter, 50g jam and 20g honey (equivalent to 580mg Ca), and (3) a lactogluconate effervescent tablet (equivalent to 500mgCa). All test doses were given on an empty stomach and labelled with 20mg 44Ca. Simultaneously, 5mg 42Ca in a sterile isotonic solution were injected intravenously. The mean values of the absorbed fractions are 24.0% +/- 5.4% (mean +/-SD), 17.9% +/- 7.1%, and 28.7% +/- 9.1% for the milk, for the meal and for the tablet respectively. The data show that less calcium is absorbed from foodstuffs as compared to a preparation of optimal bioavailability. But in this study only the difference between absorption from the milk and from the meal was statistically significant. Therefore, it is possible to obtain a sufficient calcium supply of the human body also by properly selected foodstuffs.

  4. Absorption property and nanosensing via double metal films with rectangle holes array

    NASA Astrophysics Data System (ADS)

    Chen, Fang; Zhang, Huafeng

    2016-11-01

    A theoretical investigation of plasmonic absorption and nanosensing based on a three dimensional nanostructure is presented. The structure consists of double metal films covered with rectangle nanoholes array. A dielectric layer is located between the double metal films with the function of confining electromagnetic fields. Optical absorption properties of the designed nanostructure are investigated by finite-difference time-domain method, obvious peaks appear in the absorption spectra is due to the Fabry-Perot resonance effect and localized surface plasmon resonance of the rectangle nanoholes. The absorption spectra dependence on the environmental and dielectric layer refractive index, which makes it an outstanding candidate for nanosensing. The results of this study may have potential application in absorption switching and nanosensors.

  5. Theoretical modeling of the spectroscopic absorption properties of luciferin and oxyluciferin: A critical comparison with recent experimental studies

    NASA Astrophysics Data System (ADS)

    Anselmi, Massimiliano; Marocchi, Simone; Aschi, Massimiliano; Amadei, Andrea

    2012-01-01

    Firefly luciferin and its oxidated form, oxyluciferin, are two heterocyclic compounds involved in the enzymatic reaction, catalyzed by redox proteins called luciferases, which provides the bioluminescence in a wide group of arthropods. Whereas the electronic absorption spectra of D-luciferin in water at different pHs are known since 1960s, only recently reliable experimental electronic spectra of oxyluciferin have become available. In addition oxyluciferin is involved in a triple chemical equilibria (deprotonation of the two hydroxyl groups and keto-enol tautomerism of the 4-hydroxythiazole ring), that obligates to select during an experiment a predominant species, tuning pH or solvent polarity besides introducing chemical modifications. In this study we report the absorption spectra of luciferin and oxyluciferin in each principal chemical form, calculated by means of perturbed matrix method (PMM), which allowed us to successfully introduce the effect of the solvent on the spectroscopic absorption properties, and compare the result with available experimental data.

  6. Effect of thickness on nonlinear absorption properties of graphite oxide thin films

    NASA Astrophysics Data System (ADS)

    Sreeja, V. G.; Cheruvalathu, Ajina; Reshmi, R.; Anila, E. I.; Thomas, Sheenu; Jayaraj, M. K.

    2016-10-01

    We report the thickness dependent structural, linear and nonlinear optical properties of graphite oxide (GO) thin films synthesized by spin coating method. We observed that the structural, linear and nonlinear optical properties can be tuned by the film thickness in GO. The nonlinear absorption studies by open aperture z scan technique exhibited a saturable absorption. The nonlinear absorption coefficient and saturation intensity varies with film thickness which is attributed to increased localized defect states in the energy band gap. Our results emphasize relatively large thickness dependent optical nonlinearity of GO thin films and its potential for optical pulse generation, exploring the way to GO based nonlinear applications in Q switched mode locking laser systems. All the coated GO films were characterized by X-Ray diffraction method (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-Vis absorption spectroscopy (UV-Vis), Photoluminescence (PL) and Scanning electron microscope (SEM) measurements.

  7. Size-dependent absorption properties of CdX (X = S, Se, Te) quantum dots

    NASA Astrophysics Data System (ADS)

    Yang, C. C.; Mai, Y.-W.

    2012-05-01

    A unified nanothermodynamic model was developed to study the size effects on first absorption peak energy and molar extinction coefficient of semiconductor quantum dots (QDs) based on size-dependent cohesive energy and quantum confinement effect. It is found that: (1) the first absorption peak energy increases as QD size decreases; (2) the molar extinction coefficient decreases with decreasing QD size in strong confinement regime and (3) tunable absorption properties of semiconductor QDs are caused by size-induced cohesive energy variation owing to severe bond dangling. The accuracy of the developed model was verified with experimental data of CdS, CdSe and CdTe QDs.

  8. Profiling biopharmaceutical deciding properties of absorption of lansoprazole enteric-coated tablets using gastrointestinal simulation technology.

    PubMed

    Wu, Chunnuan; Sun, Le; Sun, Jin; Yang, Yajun; Ren, Congcong; Ai, Xiaoyu; Lian, He; He, Zhonggui

    2013-09-10

    The aim of the present study was to correlate in vitro properties of drug formulation to its in vivo performance, and to elucidate the deciding properties of oral absorption. Gastrointestinal simulation technology (GST) was used to simulate the in vivo plasma concentration-time curve and was implemented by GastroPlus™ software. Lansoprazole, a typical BCS class II drug, was chosen as a model drug. Firstly, physicochemical and pharmacokinetic parameters of lansoprazole were determined or collected from literature to construct the model. Validation of the developed model was performed by comparison of the predicted and the experimental plasma concentration data. We found that the predicted curve was in a good agreement with the experimental data. Then, parameter sensitivity analysis (PSA) was performed to find the key parameters of oral absorption. The absorption was particularly sensitive to dose, solubility and particle size for lansoprazole enteric-coated tablets. With a single dose of 30 mg and the solubility of 0.04 mg/ml, the absorption was complete. A good absorption could be achieved with lansoprazole particle radius down to about 25 μm. In summary, GST is a useful tool for profiling biopharmaceutical deciding properties of absorption of lansoprazole enteric-coated tablets and guiding the formulation optimization.

  9. Physical-mechanical, moisture absorption and bioadhesive properties of hydroxypropylcellulose hot-melt extruded films.

    PubMed

    Repka, M A; McGinity, J W

    2000-07-01

    The objective of this study was to investigate the moisture absorption, physical-mechanical and bioadhesive properties of hot-melt extruded hydroxypropylcellulose (HPC) films containing polymer additives. These additives included polyethylene glycol (PEG) 5%, polycarbophil 5%, carbomer 5%, Eudragit E-100 5%, and sodium starch glycolate (SSG) 5%. Relative humidity (RH) and temperature parameters of the films studied included 25 degree C at 0, 50, 80 and 100% RH, and 40 degrees C at 0 and 100% RH, stored for 2 weeks. Tensile strength and percent elongation were determined on an Instron according to the ASTM standards. The bioadhesive properties of the HPC/PEG 3350 5% film and the polycarbophil 5% containing films, with and without PEG, were investigated in vivo on the human epidermis. Although all films studied exhibited an increase in percent water content as the percent RH increased, the SSG containing film exhibited an almost three-fold increase in percent water content compared to that of the HPC/PEG film. The temperature storage condition of 40 degrees C/100% RH (versus 25 degrees C/100% RH) increased the percent water content of the SSG containing film. Percent elongation was highest for films containing polycarbophil 5% (without PEG). In addition, the HPC film containing polycarbophil 5% exhibited a greater force of adhesion and elongation at adhesive failure in vivo, and a lower modulus of adhesion when compared to the HPC/PEG film. A novel approach to determine bioadhesion of films to the human epidermis is presented.

  10. Photo-physical properties and triplet-triplet absorption of platinum(II) acetylides in solid PMMA matrices

    NASA Astrophysics Data System (ADS)

    Glimsdal, Eirik; Westlund, Robert; Lindgren, Mikael

    2009-05-01

    Because of their strong nonlinear optical properties, Platinum(II) acetylides are investigated as potential chromophores for optical power limiting (OPL) applications. The strong excited state absorption and efficient intersystem crossing to the triplet states in these materials are desired properties for good OPL performance. We recently reported on OPL and photo-physical properties of Pt(II)-acetylide chromophores in solution, modified with thiophenyl or triazole groups. [R. Westlund et al. J. Mater. Chem. 18, 166 (2008); E. Glimsdal et al. Proc. SPIE 6740, 67400M (2007)] The chromophores were later incorporated into poly(methyl-methacrylate) (PMMA) glasses. A variety of doped organic solids were prepared, reaching concentrations of up to 13 wt% of the guest molecule. Raman spectra of the doped solid devices proved that the chemical structure of the nonlinear dyes remains intact upon the polymerization of the solid matrix. Luminescence spectra confirm that the basic photo-physical properties (absorption, emission and inter-system crossing) observed for the solute molecules in THF are maintained also in the solid state. In particular, the phosphorescence lifetime stays in the order of μs to ms, just as in the oxygen evacuated liquid samples. Also, the wavelength dependence and time-dynamics of the triplet absorption spectra of the dyes, dissolved in THF solution and dispersed in solid PMMA matrices, were investigated and compared. Ground state UV absorption spectra between 300 and 420 nm have corresponding broad band visible triplet-triplet absorption between 400 and 800 nm. The triplet state extinction coefficients were determined to be in the order of 104 M-1cm-1.

  11. Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey

    NASA Astrophysics Data System (ADS)

    Perrotta, S.; D'Odorico, V.; Prochaska, J. X.; Cristiani, S.; Cupani, G.; Ellison, S.; López, S.; Becker, G. D.; Berg, T. A. M.; Christensen, L.; Denney, K. D.; Hamann, F.; Pâris, I.; Vestergaard, M.; Worseck, G.

    2016-11-01

    We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and intervening NALs without taking into account any a priori definition or velocity cut-off. We analyse the spectra of 100 quasars with 3.5 < zem < 4.5, observed with X-shooter/Very Large Telescope in the context of the XQ-100 Legacy Survey. We detect an ˜8σ excess in the C IV number density within 10 000 km s- 1 of the quasar emission redshift with respect to the random occurrence of NALs. This excess does not show a dependence on the quasar bolometric luminosity and it is not due to the redshift evolution of NALs. It extends far beyond the standard 5000 km s- 1 cut-off traditionally defined for associated absorption lines. We propose to modify this definition, extending the threshold to 10 000 km s- 1 when weak absorbers (equivalent width < 0.2 Å) are also considered. We infer N V is the ion that better traces the effects of the quasar ionization field, offering the best statistical tool to identify intrinsic systems. Following this criterion, we estimate that the fraction of quasars in our sample hosting an intrinsic NAL system is 33 per cent. Lastly, we compare the properties of the material along the quasar line of sight, derived from our sample, with results based on close quasar pairs investigating the transverse direction. We find a deficiency of cool gas (traced by C II) along the line of sight connected to the quasar host galaxy, in contrast with what is observed in the transverse direction.

  12. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1987-01-01

    Laboratory measurements were conducted to evaluate properties of atmospheric gases under simulated conditions for the outer planets. A significant addition to this effort was the capability to make such measurements at millimeter wavelengths. Measurements should soon be completed on the millimeter wave absorption from ammonia under Jovian conditions. Also studied will be the feasibility of measuring the microwave and millimeter wave properties of phosphine (PH3) under simulated Jovian conditions. Further analysis and application of the laboratory results to microwave and millimeter wave absorption data for the outer planet, such as Voyager Radio Occultation experiments, will be pursued.

  13. Analysis and calculation of electronic properties and light absorption of defective sulfur-doped silicon and theoretical photoelectric conversion efficiency.

    PubMed

    Jiang, He; Chen, Changshui

    2015-04-23

    Most material properties can be traced to electronic structures. Black silicon produced from SF6 or sulfur powder via irradiation with femtosecond laser pulses displays decreased infrared absorption after annealing, with almost no corresponding change in visible light absorption. The high-intensity laser pulses destroy the original crystal structure, and the doping element changes the material performance. In this work, the structural and electronic properties of several sulfur-doped silicon systems are investigated using first principle calculations. Depending on the sulfur concentration (level of doping) and the behavior of the sulfur atoms in the silicon lattice, different states or an absence of states are exhibited, compared with the undoped system. Moreover, the visible-infrared light absorption intensities are structure specific. The results of our theoretical calculations show that the conversion efficiency of sulfur-doped silicon solar cells depends on the sulfur concentrations. Additionally, two types of defect configurations exhibit light absorption characteristics that differ from the other configurations. These two structures produce a rapid increase in the theoretical photoelectric conversion efficiency in the range of the specific chemical potential studied. By controlling the positions of the atomic sulfur and the sulfur concentration in the preparation process, an efficient photovoltaic (PV) material may be obtainable.

  14. Analysis and calculation of electronic properties and light absorption of defective sulfur-doped silicon and theoretical photoelectric conversion efficiency.

    PubMed

    Jiang, He; Chen, Changshui

    2015-04-23

    Most material properties can be traced to electronic structures. Black silicon produced from SF6 or sulfur powder via irradiation with femtosecond laser pulses displays decreased infrared absorption after annealing, with almost no corresponding change in visible light absorption. The high-intensity laser pulses destroy the original crystal structure, and the doping element changes the material performance. In this work, the structural and electronic properties of several sulfur-doped silicon systems are investigated using first principle calculations. Depending on the sulfur concentration (level of doping) and the behavior of the sulfur atoms in the silicon lattice, different states or an absence of states are exhibited, compared with the undoped system. Moreover, the visible-infrared light absorption intensities are structure specific. The results of our theoretical calculations show that the conversion efficiency of sulfur-doped silicon solar cells depends on the sulfur concentrations. Additionally, two types of defect configurations exhibit light absorption characteristics that differ from the other configurations. These two structures produce a rapid increase in the theoretical photoelectric conversion efficiency in the range of the specific chemical potential studied. By controlling the positions of the atomic sulfur and the sulfur concentration in the preparation process, an efficient photovoltaic (PV) material may be obtainable. PMID:25798659

  15. Food properties affecting the digestion and absorption of carbohydrates.

    PubMed

    Björck, I; Granfeldt, Y; Liljeberg, H; Tovar, J; Asp, N G

    1994-03-01

    Carbohydrate foods differ considerably in their effects on postprandial glucose and insulin responses. Qualitative differences among starchy foods are particularly intriguing because of the dominance of starch in human diets. This paper focuses on food properties in cereal (eg, pasta, bread, Arepas, and porridge) and legume products (eg, red kidney beans and lentils) that affect metabolic responses to starch. Studies in healthy subjects have found that postprandial blood glucose and insulin responses are greatly affected by food structure. Any process that disrupts the physical or botanical structure of food ingredients will increase the plasma glucose and insulin responses. The glycemic responses to bread products were reduced by the use of ingredients with an intact botanical or physical structure or a high amylose content or by enrichment with viscous dietary fiber. However, the important of a moderate increase in the amylose-amylopectin ratio and the naturally occurring levels of viscous cereal fiber is less clear. The rate of starch digestion in vitro was shown to be a key determinant of metabolic responses to most products. Assuming the sample preparation mimics chewing, in vitro enzymic procedures can be used to facilitate ranking. One such procedure, based on chewed rather than artificially disintegrated products, was recently developed and correlates well with glycemic and insulinemic indices for several starchy foods. PMID:8116553

  16. Investigation on optical absorption properties of ion irradiated single walled carbon nanotubes

    SciTech Connect

    Vishalli, Dharamvir, Keya; Kaur, Ramneek; Raina, K. K.; Avasthi, D. K.; Jeet, Kiran

    2015-08-28

    In the present study change in the optical absorption properties of single walled carbon nanotubes (SWCNTs) under nickel ion (60 MeV) irradiation at various fluences has been investigated. Langmuir Blodgett technique is used to deposit SWCNT thin film of uniform thickness. AFM analysis shows a network of interconnected bundles of nanotubes. UV-Vis-NIR absorption spectra indicate that the sample mainly contain SWCNTs of semiconducting nature. It has been found in absorption spectra that there is decrease in the intensity of the characteristic SWCNT peaks with increase in fluence. At fluence value 1×10{sup 14} ions/cm{sup 2} there is almost complete suppression of the characteristic SWCNTs peaks.The decrease in the optical absorption with increase in fluence is due to the increase in the disorder in the system which leads to the decrease in optically active states.

  17. Synthesis and microwave absorption properties of magnetite nanoparticles.

    PubMed

    Shao, XiaoPing; Dai, Bo; Zhang, XiaoWei; Ma, YongJun

    2012-02-01

    Nanoparticles of Fe3O4 with various sizes were synthesized from FeCl3 x 6H2O, FeCl2 x 4H2O and NaOH by coprecipitation process. The crystal structure, morphology, particle size and magnetic property of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). It was found that the molar ratio of ferrous to ferric played an important role in the formation of Fe3O4 nanoparticles. The particle mean diameter swelled from approximately 10 to approximately 20 nm with the molar ratio range from 1:2 to 6:1. The saturation magnetization and the coercivity increased correspondingly. The complex permittivity epsilon(r) and permeability mu(r) of the Fe3O4 mixture with paraffin were measured using vector network analysis. Values of epsilon(r), and mu(r) were used to determine the reflection loss at various sample thicknesses, based on a model of microwave absorbing layer backed by a metal plate. The minimal reflection loss or the dip shifts to a lower frequency region with increasing thickness. When the thickness is 5 mm, the minimal reflection loss of Fe3O4 synthesized with the molar ratio of 6:1 and paraffin wax composites reaches -35.1 dB at 5.2 GHz and -30.2 dB at 17.6 GHz, respectively. The minimal reflection loss is attributed to the thickness of the absorber approximates an odd number multiple of a quarter of the propagation wavelength. PMID:22629906

  18. Synthesis and microwave absorption properties of magnetite nanoparticles.

    PubMed

    Shao, XiaoPing; Dai, Bo; Zhang, XiaoWei; Ma, YongJun

    2012-02-01

    Nanoparticles of Fe3O4 with various sizes were synthesized from FeCl3 x 6H2O, FeCl2 x 4H2O and NaOH by coprecipitation process. The crystal structure, morphology, particle size and magnetic property of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). It was found that the molar ratio of ferrous to ferric played an important role in the formation of Fe3O4 nanoparticles. The particle mean diameter swelled from approximately 10 to approximately 20 nm with the molar ratio range from 1:2 to 6:1. The saturation magnetization and the coercivity increased correspondingly. The complex permittivity epsilon(r) and permeability mu(r) of the Fe3O4 mixture with paraffin were measured using vector network analysis. Values of epsilon(r), and mu(r) were used to determine the reflection loss at various sample thicknesses, based on a model of microwave absorbing layer backed by a metal plate. The minimal reflection loss or the dip shifts to a lower frequency region with increasing thickness. When the thickness is 5 mm, the minimal reflection loss of Fe3O4 synthesized with the molar ratio of 6:1 and paraffin wax composites reaches -35.1 dB at 5.2 GHz and -30.2 dB at 17.6 GHz, respectively. The minimal reflection loss is attributed to the thickness of the absorber approximates an odd number multiple of a quarter of the propagation wavelength.

  19. Enhanced Microwave Absorption Properties of Carbon Black/Silicone Rubber Coating by Frequency-Selective Surface

    NASA Astrophysics Data System (ADS)

    Yang, Zhaoning; Luo, Fa; Gao, Lu; Qing, Yuchang; Zhou, Wancheng; Zhu, Dongmei

    2016-06-01

    A square frequency-selective surface (FSS) design has been employed to improve the microwave absorption properties of carbon black/silicone rubber (CBSR) composite coating. The FSS is placed on the surface of the CBSR coating. The effects of FSS design parameters on the microwave absorption properties of the CBSR coating have been investigated, including the size and period of the FSS design, and the thickness and permittivity of the coating. Simulation results indicate that the absorption peak for the CBSR coating alone is related to its thickness and electromagnetic parameters, while the combination of the CBSR coating with a FSS can exhibit a new absorption peak in the reflection curve; the frequency of the new absorption peak is determined by the resonance of the square FSS design and tightly depends on the size of the squares, with larger squares in the FSS design leading to a lower frequency of the new absorption peak. The enhancement of the absorption performance depends on achievement of a new absorption peak using a suitable␣size and period of the FSS design. In addition, the FSS design has a stable␣frequency response for both transverse electromagnetic (TE) and transverse magnetic (TM) polarizations as the incident angle varies from 0° to 40°. The optimized results indicate that the bandwidth with reflection loss below -5 dB can encompass the whole frequency range from 8 GHz to 18 GHz for thickness of the CBSR coating of only 1.8 mm. The simulation results are confirmed by experiments.

  20. Corrosive synthesis and enhanced electromagnetic absorption properties of hollow porous Ni/SnO2 hybrids.

    PubMed

    Zhao, Biao; Zhao, Wanyu; Shao, Gang; Fan, Bingbing; Zhang, Rui

    2015-09-28

    In this study, novel porous hollow Ni/SnO2 hybrids were prepared by a facile and flexible two-step approach composed of solution reduction and subsequent reaction-induced acid corrosion. In our protocol, it can be found that the hydrothermal temperature exerts a vital influence on the phase crystal and morphology of Ni/SnO2 hybrids. Notably, the Ni microspheres might be completely corroded in the hydrothermal process at 220 °C. The complex permittivity and permeability of Ni/SnO2 hybrids-paraffin wax composite were measured based on a vector network analyzer in the frequency range of 1-18 GHz. Electromagnetic absorption properties of samples were evaluated by transmission line theory. Ni/SnO2 hybrid composites exhibit superior electromagnetic absorption properties in comparison with pristine Ni microspheres. The outstanding electromagnetic absorption performances can be observed for the hollow porous Ni/SnO2 hybrid prepared at 200 °C. The minimum reflection loss is -36.7 dB at 12.3 GHz, and the effective electromagnetic wave absorption band (RL < -10 dB, 90% microwave attenuation) was in the frequency range of 10.6-14.0 GHz with a thin thickness of 1.7 mm. Excellent electromagnetic absorption properties were assigned to the improved impedance match, more interfacial polarization and unique hollow porous structures, which can result in microwave multi-reflection and scattering. This novel hollow porous hybrid is an attractive candidate for new types of high performance electromagnetic wave-absorbing materials, which satisfies the current requirements of electromagnetic absorbing materials, which include wide-band absorption, high-efficiency absorption capability, thin thickness and light weight. PMID:26282622

  1. Studies of Microwave Absorption Properties of Carbon Nanotubes/Epoxy Composites

    NASA Astrophysics Data System (ADS)

    Zhao, Guang-Lin

    2010-10-01

    Less weight, excellent mechanical properties, and high efficiency in absorbing electromagnetic (EM) wave make carbon nanotubes (CNTs) composites attractive for microwave technology applications. Multi-walled carbon nanotubes (MWNTs) have much higher performance-to-price ratio (PPR) than SWNTs do in the composite applications. In this work, we aim to study the effect of the outside diameter (OD) distributions of MWNTs on their microwave absorption properties. We have fabricated six groups of carbon nanotube/epoxy composite samples with various OD distributions. The weight percentages of MWNTs in the composites were controlled in the range from 1 to 10%. We utilized a microwave resonant cavity technique to measure the microwave absorption properties of all the sixty samples around the central frequency of 9.968 GHz. Our results have shown that the maxima of EM wave absorptions for the six groups of samples were all around 7% MWNTs weight percentage. We further studied the effective attenuations of the electric and magnetic fields in six groups of MWNT composite samples with the same (7 %) MWNT blend in epoxy. The results show that, in general, the MWNTs with smaller diameters have higher microwave absorption at 9.968 GHz. However, sample group M5 (OD<8nm) shows unusual results, a lower microwave absorption than the other samples. We then used a scanning electron microscope (SEM) to study the morphologies of the MWNT samples. Based on the SEM analysis and microwave absorption measurements, we found that the efficiency of the microwave absorption of MWNT/Epoxy composites is strongly affected by the morphologies/structures of MWNTs in individual bundles.

  2. Relationship between mechanical-property and energy-absorption trends for composite tubes

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1992-01-01

    U.S. Army helicopters are designed to dissipate prescribed levels of crash impact kinetic energy without compromising the integrity of the fuselage. Because of the complexity of the energy-absorption process it is imperative for designers of energy-absorbing structures to develop an in-depth understanding of how and why composite structures absorb energy. A description of the crushing modes and mechanisms of energy absorption for composite tubes and beams is presented. Three primary crushing modes of composite structures including transverse shearing, lamina bending, and local buckling are described. The experimental data presented show that fiber and matrix mechanical properties and laminate stiffness and strength mechanical properties cannot reliably predict the energy-absorption response of composite tubes.

  3. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1987-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and Earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorping properties of potential constituents is available. The use of theoretically derived microwave absorption properties for such atmospheric constituents, or laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurement of the microwave properties of atmospheric gases under simulated conditions for the outer planets were conducted. Results of these measurements are discussed.

  4. TPS/PCL composite reinforced with treated sisal fibers: property, biodegradation and water-absorption

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sisal fibers bleached with sodium-hydroxide followed by hydrogen peroxide treatment were incorporated in a thermoplastic starch;-polycaprolactone (TPS/PCL) blend via extrusion processing and examined for their property, biodegradability and water-absorption. Scanning electron microscopy revealed wel...

  5. Identifying Aerosol Type/Mixture from Aerosol Absorption Properties Using AERONET

    NASA Technical Reports Server (NTRS)

    Giles, D. M.; Holben, B. N.; Eck, T. F.; Sinyuk, A.; Dickerson, R. R.; Thompson, A. M.; Slutsker, I.; Li, Z.; Tripathi, S. N.; Singh, R. P.; Zibordi, G.

    2010-01-01

    Aerosols are generated in the atmosphere through anthropogenic and natural mechanisms. These sources have signatures in the aerosol optical and microphysical properties that can be used to identify the aerosol type/mixture. Spectral aerosol absorption information (absorption Angstrom exponent; AAE) used in conjunction with the particle size parameterization (extinction Angstrom exponent; EAE) can only identify the dominant absorbing aerosol type in the sample volume (e.g., black carbon vs. iron oxides in dust). This AAE/EAE relationship can be expanded to also identify non-absorbing aerosol types/mixtures by applying an absorption weighting. This new relationship provides improved aerosol type distinction when the magnitude of absorption is not equal (e.g, black carbon vs. sulfates). The Aerosol Robotic Network (AERONET) data provide spectral aerosol optical depth and single scattering albedo - key parameters used to determine EAE and AAE. The proposed aerosol type/mixture relationship is demonstrated using the long-term data archive acquired at AERONET sites within various source regions. The preliminary analysis has found that dust, sulfate, organic carbon, and black carbon aerosol types/mixtures can be determined from this AAE/EAE relationship when applying the absorption weighting for each available wavelength (Le., 440, 675, 870nm). Large, non-spherical dust particles absorb in the shorter wavelengths and the application of 440nm wavelength absorption weighting produced the best particle type definition. Sulfate particles scatter light efficiently and organic carbon particles are small near the source and aggregate over time to form larger less absorbing particles. Both sulfates and organic carbon showed generally better definition using the 870nm wavelength absorption weighting. Black carbon generation results from varying combustion rates from a number of sources including industrial processes and biomass burning. Cases with primarily black carbon showed

  6. Microwave-Absorption Properties of Three Kinds of Structured Cu/C Composites.

    PubMed

    Jiang, Linwen; Wang, Zhenhua; Li, Da; Geng, Dianyu; Wang, Yu; An, Jing; He, Jun; Liu, Wei; Zhang, Zhidong

    2016-06-01

    The microwave-absorption properties of three kinds of (core-shell, uniform-mixing and double-layer structured) Cu/C composites are investigated in the 2-18 GHz frequency range. The results show that the Cu/C composites with core-shell structure are favorable to obtain higher relative permittivity and better microwave-absorption properties in comparison with other Cu/C composites. The reflection loss (RL) values exceeding -10 dB are obtained in 13.0-17.2 GHz at the absorber thickness of 1.6 mm for the core-shell structured Cu/C nanoparticles, which cover most of Ku-band (12-18 GHz). The excellent microwave-absorption properties may result from synergetic effects induced by the tightly-connected core-shell interfaces. The synergetic effects are explained by a simulated physical model, wherein both the interfacial polarizations and interfacial multiple reflections are responsible to the excellent microwave-absorption performances.

  7. CoxFey@C Composites with Tunable Atomic Ratios for Excellent Electromagnetic Absorption Properties

    PubMed Central

    Lv, Hualiang; Ji, Guangbin; Zhang, Haiqian; Li, Meng; Zuo, Zhongzheng; Zhao, Yue; Zhang, Baoshan; Tang, Dongming; Du, Youwei

    2015-01-01

    The shell on the nano-magnetic absorber can prevent oxidation, which is very important for its practical utilization. Generally, the nonmagnetic shell will decrease the integral magnetic loss and thus weaken the electromagnetic absorption. However, maintaining the original absorption properties of the magnetic core is a major challenge. Here, we designed novel and facile CoxFey@C composites by reducing CoxFe3−xO4@phenolic resin (x = 1, 0.5 and 0.25). High saturation magnetization value (Ms) of CoxFey particle, as a core, shows the interesting magnetic loss ability. Meanwhile, the carbon shell may increase the integral dielectric loss. The resulting composite shows excellent electromagnetic absorption properties. For example, at a coating thickness of 2 mm, the RLmin value can reach to −23 dB with an effective frequency range of 7 GHz (11–18 GHz). The mechanisms of the improved microwave absorption properties are discussed. PMID:26659124

  8. CoxFey@C Composites with Tunable Atomic Ratios for Excellent Electromagnetic Absorption Properties

    NASA Astrophysics Data System (ADS)

    Lv, Hualiang; Ji, Guangbin; Zhang, Haiqian; Li, Meng; Zuo, Zhongzheng; Zhao, Yue; Zhang, Baoshan; Tang, Dongming; Du, Youwei

    2015-12-01

    The shell on the nano-magnetic absorber can prevent oxidation, which is very important for its practical utilization. Generally, the nonmagnetic shell will decrease the integral magnetic loss and thus weaken the electromagnetic absorption. However, maintaining the original absorption properties of the magnetic core is a major challenge. Here, we designed novel and facile CoxFey@C composites by reducing CoxFe3-xO4@phenolic resin (x = 1, 0.5 and 0.25). High saturation magnetization value (Ms) of CoxFey particle, as a core, shows the interesting magnetic loss ability. Meanwhile, the carbon shell may increase the integral dielectric loss. The resulting composite shows excellent electromagnetic absorption properties. For example, at a coating thickness of 2 mm, the RLmin value can reach to -23 dB with an effective frequency range of 7 GHz (11-18 GHz). The mechanisms of the improved microwave absorption properties are discussed.

  9. Near-infrared radiation absorption properties of covellite (CuS) using first-principles calculations

    NASA Astrophysics Data System (ADS)

    Xiao, Lihua; Wu, Jianming; Ran, Jingyu; Liu, Yike; Qiu, Wei; Lu, Fanghai; Shao, Fang; Tang, Dongsheng; Peng, Ping

    2016-08-01

    First-principles density functional theory was used to investigate the electronic structure, optical properties and the origin of the near-infrared (NIR) absorption of covellite (CuS). The calculated lattice constant and optical properties are found to be in reasonable agreement with experimental and theoretical findings. The electronic structure reveals that the valence and conduction bands of covellite are determined by the Cu 3d and S 3p states. By analyzing its optical properties, we can fully understand the potential of covellite (CuS) as a NIR absorbing material. Our results show that covellite (CuS) exhibits NIR absorption due to its metal-like plasma oscillation in the NIR range.

  10. Optical absorption and emission properties of Nd3+-doped oxyfluorosilicate glasses for solid state lasers

    NASA Astrophysics Data System (ADS)

    Ramachari, D.; Rama Moorthy, L.; Jayasankar, C. K.

    2014-11-01

    Optical absorption and near-infrared luminescent properties of Nd3+ ions doped oxyfluorosilicate (NKZLSNd) glasses were investigated. Raman spectrum was recorded to investigate the structural properties of NKZLSNd glasses. The Judd-Ofelt theory (JO) has been applied to the absorption spectrum of 1.0 mol% Nd3+-doped oxyfluorosilicate glass to derive the JO intensity parameters (Ωλ), which are in turn used to calculate the radiative properties of Nd3+ ions luminescent levels. The near-infrared emission spectra recorded with 808 nm laser diode excitation revealed the effective bandwidths values around 30-40 nm for the 4F3/2 level of Nd3+-doped oxyfluorosilicate glasses. The measured decay times of 4F3/2 level decreased with increasing Nd3+ ions concentration due to the concentration quenching.

  11. Optical properties of Mg-doped VO2: Absorption measurements and hybrid functional calculations

    NASA Astrophysics Data System (ADS)

    Hu, Shuanglin; Li, S.-Y.; Ahuja, R.; Granqvist, C. G.; Hermansson, K.; Niklasson, G. A.; Scheicher, R. H.

    2012-11-01

    Mg-doped VO2 thin films with thermochromic properties were made by reactive DC magnetron co-sputtering onto heated substrates, and spectral absorption was recorded at room temperature in the 0.5 < ħω < 3.5 eV energy range. Clear evidence was found for a widening of the main band gap from 1.67 to 2.32 eV as the Mg/(V + Mg) atomic ratio went from zero to 0.19, thereby significantly lowering the luminous absorption. This technologically important effect could be reconciled with spin-polarized density functional theory calculations using the Heyd-Scuseria-Ernzerhof [Heyd et al., J. Chem. Phys. 118, 8207 (2003); ibid. 124, 219906 (2006)] hybrid functional. Specifically, the calculated luminous absorptance decreased when the Mg/(V + Mg) ratio was increased from 0.125 to 0.250.

  12. Tuning optical and three photon absorption properties in graphene oxide-polyvinyl alcohol free standing films

    NASA Astrophysics Data System (ADS)

    Karthikeyan, B.; Udayabhaskar, R.; Hariharan, S.

    2016-07-01

    We report the optical and nonlinear optical properties of graphene oxide (GO)-polyvinyl alcohol (PVA) free standing films. The composite polymer films were prepared in ex-situ method. The variation in optical absorption spectra and optical constants with the amount of GO loading was noteworthy from the optical absorption spectroscopic studies. Nonlinear optical studies done at 532 nm using 5 ns laser pulses show three photon absorption like behaviour. Both steady state and time resolved fluorescence studies reveal that the GO was functioning as a pathway for the decay of fluorescence from PVA. This is attributed to the energy level modifications of GO through hydroxyl groups with PVA. Raman spectroscopy also supports the interaction between GO and PVA ions through OH radicals.

  13. Optical properties of Mg-doped VO{sub 2}: Absorption measurements and hybrid functional calculations

    SciTech Connect

    Hu Shuanglin; Li, S.-Y.; Granqvist, C. G.; Niklasson, G. A.; Ahuja, R.; Scheicher, R. H.; Hermansson, K.

    2012-11-12

    Mg-doped VO{sub 2} thin films with thermochromic properties were made by reactive DC magnetron co-sputtering onto heated substrates, and spectral absorption was recorded at room temperature in the 0.5 < h{omega} < 3.5 eV energy range. Clear evidence was found for a widening of the main band gap from 1.67 to 2.32 eV as the Mg/(V + Mg) atomic ratio went from zero to 0.19, thereby significantly lowering the luminous absorption. This technologically important effect could be reconciled with spin-polarized density functional theory calculations using the Heyd-Scuseria-Ernzerhof [Heyd et al., J. Chem. Phys. 118, 8207 (2003); ibid. 124, 219906 (2006)] hybrid functional. Specifically, the calculated luminous absorptance decreased when the Mg/(V + Mg) ratio was increased from 0.125 to 0.250.

  14. High-throughput approaches for evaluating absorption, distribution, metabolism and excretion properties of lead compounds.

    PubMed

    Tarbit, M H; Berman, J

    1998-06-01

    Combinatorial chemistry methods and high-throughput screening for leads in industrial drug discovery have generated a potential bottleneck in the optimisation processes that seek to align potency with good pharmacokinetics in order to produce good medicines. This has resulted in the need for higher throughput methods of screening for absorption, distribution, metabolism and excretion properties. Significant progress has been made in throughput of in vivo pharmacokinetic studies, with the introduction of cassette, or multiple-in-one, protocols. In this technique, typically up to ten compounds are administered in one dose and analysed concomitantly on the mass spectrometer. High-throughput methods in in vitro absorption, distribution, metabolism and excretion are less well-developed as yet, and current approaches comprise automation of well-established methods for absorption using cell lines and metabolism using liver microsomes.

  15. Carbon dioxide absorption and release properties of pyrolysis products of dolomite calcined in vacuum atmosphere.

    PubMed

    Wang, Fei; Kuzuya, Toshihiro; Hirai, Shinji; Li, Jihua; Li, Te

    2014-01-01

    The decomposition of dolomite into CaO and MgO was performed at 1073 K in vacuum and at 1273 K in an Ar atmosphere. The dolomite calcined in vacuum was found to have a higher specific surface area and a higher micropore volume when compared to the dolomite calcined in the Ar atmosphere. These pyrolysis products of dolomite were reacted with CO2 at 673 K for 21.6 ks. On the absorption of CO2, the formation of CaCO3 was observed. The degree of absorption of the dolomite calcined in vacuum was determined to be above 50%, which was higher than the degree of absorption of the dolomite calcined in the Ar atmosphere. The CO2 absorption and release procedures were repeated three times for the dolomite calcined in vacuum. The specific surface area and micropore volume of calcined dolomite decreased with successive repetitions of the CO2 absorption and release cycles leading to a decrease in the degree of absorption of CO2. PMID:25136696

  16. Carbon Dioxide Absorption and Release Properties of Pyrolysis Products of Dolomite Calcined in Vacuum Atmosphere

    PubMed Central

    Wang, Fei; Kuzuya, Toshihiro; Hirai, Shinji; Li, Jihua; Li, Te

    2014-01-01

    The decomposition of dolomite into CaO and MgO was performed at 1073 K in vacuum and at 1273 K in an Ar atmosphere. The dolomite calcined in vacuum was found to have a higher specific surface area and a higher micropore volume when compared to the dolomite calcined in the Ar atmosphere. These pyrolysis products of dolomite were reacted with CO2 at 673 K for 21.6 ks. On the absorption of CO2, the formation of CaCO3 was observed. The degree of absorption of the dolomite calcined in vacuum was determined to be above 50%, which was higher than the degree of absorption of the dolomite calcined in the Ar atmosphere. The CO2 absorption and release procedures were repeated three times for the dolomite calcined in vacuum. The specific surface area and micropore volume of calcined dolomite decreased with successive repetitions of the CO2 absorption and release cycles leading to a decrease in the degree of absorption of CO2. PMID:25136696

  17. Structure and microwave absorption properties of Pr-Fe-Ni alloys

    NASA Astrophysics Data System (ADS)

    Xiong, Jilei; Pan, Shunkang; Cheng, Lichun; Liu, Xing; Lin, Peihao

    2015-06-01

    The Pr2Fe17-xNix (X=0.0, 0.2, 0.6, 1.0) alloy powders were obtained by arc smelting and high energy ball milling method. The phase structure, morphology and particle size of the powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser diffraction-based particle size analyzer, respectively. The saturation magnetization and electromagnetic parameters were determined by vibrating sample magnetometer (VSM) and vector network analyzer (VNA), respectively. The results indicate that the lattice parameter and the saturation magnetization of Pr2Fe17-xNix alloys decrease with increasing Ni content. And the minimum absorption peak frequency shifts towards the higher region with increasing Ni content. Compared to the powders without heat treatment, the powders tempered at 100 °C for 2 h have better absorbing properties. The minimum reflectivity peak value of Pr2Fe16Ni alloy reaches about -23.6 dB at 2.72 GHz with the matching thickness of 3.5 mm.

  18. Light absorption properties of CDOM in the Changjiang (Yangtze) estuarine and coastal waters: An alternative approach for DOC estimation

    NASA Astrophysics Data System (ADS)

    Yu, Xiaolong; Shen, Fang; Liu, Yangyang

    2016-11-01

    Field measurements of CDOM absorption properties and DOC concentrations were collected in the Changjiang estuarine and coastal waters from 2011 to 2013. CDOM absorption coefficient at 355 nm (ag (355)) was found to be inversely correlated with salinity, with Pearson's coefficients r of -0.901 and -0.826 for summer and winter observations, respectively. Analysis results of the relationships between salinity and CDOM optical properties (i.e., absorption coefficient and spectral slope) suggested that terrigenous inputs dominated CDOM sources in the Changjiang estuary, but the proportion of terrigenous CDOM declined with increasing salinity. The level of CDOM in the Changjiang estuary was lower compared to some of the major estuaries in the world, which could be attributed to several controlling factors such as vegetation cover in the drainage basin, the origin of recharged streams and high sediment load in the Changjiang estuary. We further evaluated the relationships between CDOM and DOC and their mixing behavior among world's major estuaries. An empirical model was finally developed to estimate DOC concentration from ag (355) and spectral slope S275-295 using a non-linear regression. This empirical relationship was calibrated using the Cal dataset, and was validated with the Val dataset, resulting in an acceptable error with the R2 of 0.746, the RMSE of 20.99 μmol/L and the rMAD of 14.46%.

  19. [Phytoplankton Light Absorption Properties During the Blooms in Adjacent Waters of the Changjiang Estuary].

    PubMed

    Liu, Yang-yang; Shen, Fang; Li, Xiu-zhen

    2015-06-01

    Phytoplankton dominant species and their light absorption properties during the blooms occurred in August 2013 in adjacent waters of the Changjiang Estuary were analyzed. The results showed that phytoplankton blooms broke out in 10 out of 34 investigation stations, among which diatom blooms occurred in 6 stations while 3 stations were predominated by dinoflagellate. Phytoplankton absorption coefficients of both bloom and non-bloom waters exhibited large variations, with respective ranges of 0.199-0.832 m(-1) and 0.012-0.109 m(-1), while phytoplankton specific absorption coefficients spanned much narrower range, with the average values of bloom and non-bloom waters being 0.023 and 0.035 m2 x mg(-1), respectively. When transitioned from bloom to non-bloom waters, the proportion of phytoplankton with larger cell size lowered while that of smaller phytoplankton elevated, causing a less extent of package effect and thus higher specific absorption coefficients. Distinctive absorption spectra were observed between different types of bloom (such as diatom and dinoflagellate blooms) with similar phytoplankton cell size, mostly attributed to distinctive accessory pigment composition. The ratios of diadinoxanthin and chlorophyll-c2 concentrations to chlorophyll-a concentration in dinoflagellate blooms were higher than those in diatom blooms, which largely contributed to the shoulder peaks at 465 nm in dinoflagellate blooms.

  20. Constraints on Reionization and Source Properties from the Absorption Spectra of z > 6.2 Quasars

    NASA Astrophysics Data System (ADS)

    Mesinger, Andrei; Haiman, Zoltán

    2007-05-01

    We make use of hydrodynamical simulations of the intergalactic medium (IGM) to create model quasar absorption spectra. We compare these model spectra with the observed Keck spectra of three z>6.2 quasars with full Gunn-Peterson troughs: SDSS J1148+5251 (z=6.42), SDSS J1030+0524 (z=6.28), and SDSS J1623+3112 (z=6.22). We fit the probability density distributions (PDFs) of the observed Lyα optical depths (τα) with those generated from the simulation by exploring a range of values for the size of the quasar's surrounding H II region, RS; the volume-weighted mean neutral hydrogen fraction in the ambient IGM, x¯HI; and the quasar's ionizing photon emissivity, N˙Q. In order to avoid averaging over possibly large sight line-to-sight line fluctuations in IGM properties, we analyze each observed quasar independently. We find the following results for J1148+5251, J1030+0524, and J1623+3112: the best-fit sizes RS are 40, 41, and 29 (comoving) Mpc, respectively. For the later two quasars, the value is significantly larger than the radius corresponding to the wavelength at which the quasar's flux vanishes. These constraints are tight, with only ~10% uncertainties, comparable to those caused by redshift determination errors. The best-fit values of N˙Q are 2.1, 1.3, and 0.9×1057 s-1, respectively, with a factor of ~2 uncertainty in each case. Finally, the best-fit values of x¯HI are 0.16, 1.0, and 1.0, respectively. The uncertainty in the case of J1148+5251 is large, and x¯HI is not well constrained. However, for both J1030+0524 and J1623+3112, we find a significant lower limit of x¯HI>~0.033. Our method is different from previous analyses of the GP absorption spectra of these quasars, and our results strengthen the evidence that the rapid end stage of reionization is occurring near z~6.

  1. Absorption and scattering properties of carbon nanohorn-based nanofluids for direct sunlight absorbers

    PubMed Central

    2011-01-01

    In the present work, we investigated the scattering and spectrally resolved absorption properties of nanofluids consisting in aqueous and glycol suspensions of single-wall carbon nanohorns. The characteristics of these nanofluids were evaluated in view of their use as sunlight absorber fluids in a solar device. The observed nanoparticle-induced differences in optical properties appeared promising, leading to a considerably higher sunlight absorption with respect to the pure base fluids. Scattered light was found to be not more than about 5% with respect to the total attenuation of light. Both these effects, together with the possible chemical functionalization of carbon nanohorns, make this new kind of nanofluids very interesting for increasing the overall efficiency of the sunlight exploiting device. PACS 78.40.Ri, 78.35.+c, 78.67.Bf, 88.40.fh, 88.40.fr, 81.05.U. PMID:21711795

  2. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1988-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The key activity for this grant year has continued to be laboratory measurements of the microwave and millimeter-wave properties of the simulated atmospheres of the outer planets and their satellites. A Fabry-Perot spectrometer system capable of operation from 32 to 41 GHz was developed. Initially this spectrometer was used to complete laboratory measurements of the 7.5 to 9.3 mm absorption spectrum of ammonia. Laboratory measurements were begun at wavelengths near 3.2 mm, where a large number of observations of the emission from the outer planets were made. A description of this system is presented.

  3. Percutaneous absorption of benzophenone-3 loaded lipid nanoparticles and polymeric nanocapsules: A comparative study.

    PubMed

    Gilbert, E; Roussel, L; Serre, C; Sandouk, R; Salmon, D; Kirilov, P; Haftek, M; Falson, F; Pirot, F

    2016-05-17

    For the last years, the increase of the number of skin cancer cases led to a growing awareness of the need of skin protection against ultraviolet (UV) radiations. Chemical UV filters are widely used into sunscreen formulations as benzophenone-3 (BP-3), a usually used broad spectrum chemical UV filter that has been shown to exercise undesirable effects after topical application. Innovative sunscreen formulations are thus necessary to provide more safety to users. Lipid carriers seem to be a good alternative to formulate chemical UV filters reducing their skin penetration while maintaining good photo-protective abilities. The aim of this work was to compare percutaneous absorption and cutaneous bioavailability of BP-3 loaded into solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), nanostructured polymeric lipid carriers (NPLC) and nanocapsules (NC). Particle size, zeta potential and in vitro sun protection factor (SPF) of nanoparticle suspensions were also investigated. Results showed that polymeric lipid carriers, comprising NPLC and NC, significantly reduced BP-3 skin permeation while exhibiting the highest SPF. This study confirms the interesting potential of NPLC and NC to formulate chemical UV filters. PMID:26976501

  4. Ultrafast recovery time and broadband saturable absorption properties of black phosphorus suspension

    SciTech Connect

    Wang, Yingwei; Huang, Guanghui; Chen, Jiazhang; Xiao, Si He, Jun; Mu, Haoran; Bao, Qiaoliang; Lin, Shenghuang

    2015-08-31

    As a new type of two-dimensional crystal material, black phosphorus (BP) exhibits excellent electronics and optical performance. Herein, we focus on carrier relaxation dynamics and nonlinear optical properties of BP suspension. Atomic force microscopy, transmission electron microscopy, and optical transmission spectrum are employed to characterize the structure and linear optical properties of the BP. Additionally, pump-probe experiments at wavelength of 1550 nm were carried out to study the carrier dynamics in BP suspension, and ultrafast recovery time was observed (τ{sub s} = 24 ± 2 fs). Furthermore, we demonstrate the saturable absorption signals by open aperture Z-scan experiments at wavelengths of 1550 nm, 532 nm, and 680 nm. The results indicate that BP has broadband saturable absorption properties and the nonlinear absorption coefficients were determined to be β{sub 2} = −0.20 ± 0.08 × 10{sup −3 }cm/GW (532 nm), β{sub 2} = −0.12 ± 0.05 × 10{sup −3 }cm/GW (680 nm), and β{sub 2} = −0.15 ± 0.09 × 10{sup −3 }cm/GW (1550 nm)

  5. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and Earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often lead to significant misinterpretation of available opacity data. Steffes and Eshleman showed that under environmental conditions corresponding to the middle atmosphere of Venus, the microwave absorption due to atmospheric SO2 was 50 percent greater than that calculated from Van Vleck-Weiskopff theory. Similarly, the opacity from gaseous H2SO4 was found to be a factor of 7 greater than theoretically predicted for conditions of the Venus middle atmosphere. The recognition of the need to make such measurements over a range of temperatures and pressures which correspond to the periapsis altitudes of radio occultation experiments, and over a range of frequencies which correspond to both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements.

  6. Mammalian gastrointestinal tract parameters modulating the integrity, surface properties, and absorption of food-relevant nanomaterials.

    PubMed

    Bellmann, Susann; Carlander, David; Fasano, Alessio; Momcilovic, Dragan; Scimeca, Joseph A; Waldman, W James; Gombau, Lourdes; Tsytsikova, Lyubov; Canady, Richard; Pereira, Dora I A; Lefebvre, David E

    2015-01-01

    Many natural chemicals in food are in the nanometer size range, and the selective uptake of nutrients with nanoscale dimensions by the gastrointestinal (GI) tract is a normal physiological process. Novel engineered nanomaterials (NMs) can bring various benefits to food, e.g., enhancing nutrition. Assessing potential risks requires an understanding of the stability of these entities in the GI lumen, and an understanding of whether or not they can be absorbed and thus become systemically available. Data are emerging on the mammalian in vivo absorption of engineered NMs composed of chemicals with a range of properties, including metal, mineral, biochemical macromolecules, and lipid-based entities. In vitro and in silico fluid incubation data has also provided some evidence of changes in particle stability, aggregation, and surface properties following interaction with luminal factors present in the GI tract. The variables include physical forces, osmotic concentration, pH, digestive enzymes, other food, and endogenous biochemicals, and commensal microbes. Further research is required to fill remaining data gaps on the effects of these parameters on NM integrity, physicochemical properties, and GI absorption. Knowledge of the most influential luminal parameters will be essential when developing models of the GI tract to quantify the percent absorption of food-relevant engineered NMs for risk assessment.

  7. Spin canting effect and microwave absorption properties of Sm-Mn substituted nanosized material

    NASA Astrophysics Data System (ADS)

    Sadiq, Imran; Naseem, Shahzad; Naeem Ashiq, Muhammad; Asif Iqbal, M.; Ali, Irshad; Khan, M. A.; Niaz, Shanawar; Rana, M. U.

    2015-12-01

    In order to understand the substitutional effect of rare earth element Sm3+ and divalent Mn2+ on structural, magnetic and microwave absorption properties of hexagonal ferrites, a series of Sr2-x Smx Ni2 Fe28-yMnyO46 X-type hexagonal ferrites with concentration (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10 and y=0, 0.1, 0.2, 0.3, 0.4, 0.5) was synthesized by the sol-gel method. The XRD analysis shows that the material crystallized into single X-type hexagonal phase. The absorption bands at low wave number in FTIR curves are the characteristics of the X-type hexagonal ferrites. Decreasing trend in the magnetic properties with the substitution of Sm-Mn contents was also observed, which may be attributed to the oxidation of Mn2+ ions into Mn3+ ions and spin canting effect of rare earth element Sm3+. The reflection loss peak shifted towards the low frequency and microwave absorption properties of the material enhanced with the substitution of Sm-Mn contents which reflects its applications in super high frequency (SHF) devices. The attenuation constant curves are in good agreement with the reflection loss peak.

  8. A Synthesis of Light Absorption Properties of the Arctic Ocean: Application to Semi-analytical Estimates of Dissolved Organic Carbon Concentrations from Space

    NASA Technical Reports Server (NTRS)

    Matsuoka, A.; Babin, M.; Doxaran, D.; Hooker, S. B.; Mitchell, B. G.; Belanger, S.; Bricaud, A.

    2014-01-01

    The light absorption coefficients of particulate and dissolved materials are the main factors determining the light propagation of the visible part of the spectrum and are, thus, important for developing ocean color algorithms. While these absorption properties have recently been documented by a few studies for the Arctic Ocean [e.g., Matsuoka et al., 2007, 2011; Ben Mustapha et al., 2012], the datasets used in the literature were sparse and individually insufficient to draw a general view of the basin-wide spatial and temporal variations in absorption. To achieve such a task, we built a large absorption database at the pan-Arctic scale by pooling the majority of published datasets and merging new datasets. Our results showed that the total non-water absorption coefficients measured in the Eastern Arctic Ocean (EAO; Siberian side) are significantly higher 74 than in the Western Arctic Ocean (WAO; North American side). This higher absorption is explained 75 by higher concentration of colored dissolved organic matter (CDOM) in watersheds on the Siberian 76 side, which contains a large amount of dissolved organic carbon (DOC) compared to waters off 77 North America. In contrast, the relationship between the phytoplankton absorption (a()) and chlorophyll a (chl a) concentration in the EAO was not significantly different from that in the WAO. Because our semi-analytical CDOM absorption algorithm is based on chl a-specific a() values [Matsuoka et al., 2013], this result indirectly suggests that CDOM absorption can be appropriately erived not only for the WAO but also for the EAO using ocean color data. Derived CDOM absorption values were reasonable compared to in situ measurements. By combining this algorithm with empirical DOC versus CDOM relationships, a semi-analytical algorithm for estimating DOC concentrations for coastal waters at the Pan-Arctic scale is presented and applied to satellite ocean color data.

  9. Modification of fish skin collagen film and absorption property of tannic acid.

    PubMed

    Liu, Haiying; Zhao, Lu; Guo, Shidong; Xia, Yu; Zhou, Peng

    2014-06-01

    Fish collagen is a biomacromolecule material and is usually used as a clarifying agent. However, fish collagen is not recyclable, and sedimentation usually occurs in the clarification process using fish collagen so that the filtration process is inevitable. This work aimed to provide a recyclable modified fish skin collagen film (MFCF) for adsorption of tannic acids. The collagen from channel catfish skin was extracted and used for preparation of the fish skin collagen film (FCF) and MFCF. The result indicated that the mechanical properties of MFCF were improved by addition of 2 ml/L glycerol, 6 ml/L polyvinyl alcohol (PVA) and 2 ml/L glutaraldehyde in 15 g/L collagen solution. As the most important property of adsorption material, the hydroscopicity of MFCF was only 54%, significantly lower than that of FCF (295%). Therefore, MFCF would not collapse in water. The infrared and thermal properties of MFCF were also investigated in this work. Results indicated that, in comparison to FCF, the physical and chemical properties of MFCF had been improved significantly. MFCF had higher shrink temperature (79.3 °C) and it did not collapse in distilled water at normal temperature. Furthermore, absorption and desorption properties of tannic acid were studied. MFCF showed good capability of absorption and desorption of tannic acid, which leaded to the suggestion that MFCF could have potential applications in adsorption material.

  10. Modification of fish skin collagen film and absorption property of tannic acid.

    PubMed

    Liu, Haiying; Zhao, Lu; Guo, Shidong; Xia, Yu; Zhou, Peng

    2014-06-01

    Fish collagen is a biomacromolecule material and is usually used as a clarifying agent. However, fish collagen is not recyclable, and sedimentation usually occurs in the clarification process using fish collagen so that the filtration process is inevitable. This work aimed to provide a recyclable modified fish skin collagen film (MFCF) for adsorption of tannic acids. The collagen from channel catfish skin was extracted and used for preparation of the fish skin collagen film (FCF) and MFCF. The result indicated that the mechanical properties of MFCF were improved by addition of 2 ml/L glycerol, 6 ml/L polyvinyl alcohol (PVA) and 2 ml/L glutaraldehyde in 15 g/L collagen solution. As the most important property of adsorption material, the hydroscopicity of MFCF was only 54%, significantly lower than that of FCF (295%). Therefore, MFCF would not collapse in water. The infrared and thermal properties of MFCF were also investigated in this work. Results indicated that, in comparison to FCF, the physical and chemical properties of MFCF had been improved significantly. MFCF had higher shrink temperature (79.3 °C) and it did not collapse in distilled water at normal temperature. Furthermore, absorption and desorption properties of tannic acid were studied. MFCF showed good capability of absorption and desorption of tannic acid, which leaded to the suggestion that MFCF could have potential applications in adsorption material. PMID:24876642

  11. Screening micro-organisms for cadmium absorption from aqueous solution and cadmium absorption properties of Arthrobacter nicotianae.

    PubMed

    Tsuruta, Takehiko; Umenai, Daishi; Hatano, Tomonobu; Hirajima, Tsuyoshi; Sasaki, Keiko

    2014-01-01

    To obtain basic information on how microbial cells absorb cadmium from aqueous solution, we examined cadmium absorption in various micro-organisms. Of 51 micro-organism strains tested, we found that some Gram-positive bacteria, such as, Arthrobacter nicotianae and Bacillus subtilis, and some actinomycetes, such as, Streptomyces flavoviridis and S. levoris were highly capable of absorbing cadmium from an aqueous solution. A. nicotianae absorbed the largest amount of cadmium, over 800 μmol cadmium per gram of dry wt. cells. However, cadmium absorption by A. nicotianae was affected by the solution pH, cadmium concentration, and cell density. The absorption of cadmium was very rapid. Some factors that affected cadmium absorption by A. nicotianae cells were also discussed.

  12. Absorption and scattering properties of organic carbon versus sulfate dominant aerosols at Gosan climate observatory in Northeast Asia

    NASA Astrophysics Data System (ADS)

    Lim, S.; Lee, M.; Kim, S.-W.; Yoon, S.-C.; Lee, G.; Lee, Y. J.

    2014-08-01

    Carbonaceous and soluble ionic species of PM1.0 and PM10 were measured along with the absorption and scattering properties and aerosol number size distributions at Gosan Climate Observatory (GCO) from January to September 2008. The daily averaged equivalent black carbon (EBC) measured as aerosol absorption exhibited two types of spectral dependence with a distinct maximum (peak) at either 370 nm or 880 nm, by which two subsets were extracted and classified into the respective groups (370 and 880 nm). The 370 nm group was distinguished by high organic carbon (OC) concentrations relative to elemental carbon (EC) and sulfate, but sulfate was predominant for the 880 nm group. The PM1.0 OC of the 370 nm group was mainly composed of refractory and pyrolized components that correlated well with PM1.0 EC1, referred to as char EC, which suggests biofuel and biomass combustion as the source of these OC fractions, particularly during winter. The scanning electron microscope (SEM) images and the number size distributions implied that aerosols of the 370 nm group were externally mixed upon transport in fast-moving air masses that passed through the Beijing area in about one day. In contrast, the aerosols of the 880 nm group were characterized by high sulfate concentrations, and seemed to be internally mixed during slow transport over the Yellow Sea region over approximately 2 to 4 days. The absorption and scattering coefficients of the 880 nm group were noticeably higher compared to those of the 370 nm group. The average absorption ångström exponent (AAE) was estimated to be 1.29 and 1.0 for the 370 and 880 nm groups, respectively, in the range 370-950 nm. These results demonstrated that the optical properties of aerosols were intimately linked to chemical composition and mixing state, characteristics determined both by source and atmospheric aging processes. In OC dominant aerosols, absorption was enhanced in the UV region, which was possibly due to refractory and pyrolized

  13. MOF-Derived Porous Co/C Nanocomposites with Excellent Electromagnetic Wave Absorption Properties.

    PubMed

    Lü, Yinyun; Wang, Yiting; Li, Hongli; Lin, Yuan; Jiang, Zhiyuan; Xie, Zhaoxiong; Kuang, Qin; Zheng, Lansun

    2015-06-24

    Composites incorporating ferromagnetic metal nanopartices into a highly porous carbon matrix are promising as electromagnetic wave absorption materials. Such special composite nanomaterials are potentially prepared by the thermal decomposition of metal-organic framework (MOF) materials under controlled atmospheres. In this study, using Co-based MOFs (Co-MOF, ZIF-67) as an example, the feasibility of this synthetic strategy was demonstrated by the successful fabrication of porous Co/C composite nanomaterials. The atmosphere and temperature for the thermal decomposition of MOF precursors were crucial factors for the formation of the ferromagnetic metal nanopartices and carbon matrix in the porous Co/C composites. Among the three Co/C composites obtained at different temperatures, Co/C-500 obtained at 500 °C exhibited the best performance for electromagnetic wave absorption. In particular, the maximum reflection loss (RL) of Co/C-500 reached -35.3 dB, and the effective absorption bandwidth (RL ≤ -10 dB) was 5.80 GHz (8.40 GHz-14.20 GHz) corresponding to an absorber thickness of 2.5 mm. Such excellent electromagnetic wave absorption properties are ascribed to the synergetic effects between the highly porous structure and multiple components, which significantly improved impedance matching.

  14. Ultrawide Band Microwave Absorption Properties of Ultrasound Processed CrO2-Paraffin Wax Composites

    NASA Astrophysics Data System (ADS)

    Xi, Li; Yang, Yikai

    2011-03-01

    The microwave absorption properties of ultrasound processed CrO2-paraffin wax composites are investigated in the frequency range of 0.1-18 GHz by the coaxial method. By analysis and comparison between ultrasound processed sample and the unprocessed sample, we discovered that the ultrasound treatment will induce a thin insulating Cr2O3 shell over the CrO2 rods to form a core/shell structure that performs excellent in microwave absorption. An optimum reflection loss of -50.9 dB was found at 5.2 GHz with a matching thickness of 3.4 mm for 70 wt % CrO2-paraffin wax composite. Moreover, the frequency range of which the reflection loss is less than -20 dB spreads from 4.0 to 8.7 GHz with the corresponding absorption thickness ranges from 2.3 to 4.0 mm. The comparison among our result and other reported ones indicates that, in addition to its common applications, the CrO2 after certain process may have potential in microwave absorption. More profoundly, the technique of ultrasound process employed in this report may suggest a new method to induce, according to different needs, crystalline phase transition for a various range of metastable chemicals.

  15. Facile synthesis of BaTiO3 nanotubes and their microwave absorption properties.

    PubMed

    Zhu, Yao-Feng; Zhang, Li; Natsuki, Toshiaki; Fu, Ya-Qin; Ni, Qing-Qing

    2012-04-01

    Uniform BaTiO(3) nanotubes were synthesized via a simple wet chemical route at low temperature (50 °C). The as-synthesized BaTiO(3) nanotubes were characterized using powder X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The results show that the BaTiO(3) nanotubes formed a cubic phase with an average diameter of ~10 nm and wall thickness of 3 nm at room temperature. The composition of the mixed solvent (ethanol and deionized water) was a key factor in the formation of these nanotubes; we discuss possible synthetic mechanisms. The microwave absorption properties of the BaTiO(3) nanotubes were studied at microwave frequencies between 0.5 and 15 GHz. The minimum reflection loss of the BaTiO(3) nanotubes/paraffin wax composite (BaTiO(3) nanotubes weight fraction = 70%) reached 21.8 dB (~99.99% absorption) at 15 GHz, and the frequency bandwidth less than -10 dB is from 13.3 to 15 GHz. The excellent absorption property of BaTiO(3) nanotubes at high frequency indicates that these nanotubes could be promising microwave-absorbing materials. PMID:22409350

  16. Electrical and absorption properties of fresh cassava tubers and cassava starch

    NASA Astrophysics Data System (ADS)

    Harnsoongnoen, S.; Siritaratiwat, A.

    2015-09-01

    The objective of this study was to analyze the electrical and absorption properties of fresh cassava tubers and cassava starch at various frequencies using electric impedance spectroscopy and near-infrared spectroscopy, as well as determine the classification of the electrical parameters of both materials using the principle component analysis (PCA) method. All samples were measured at room temperature. The electrical and absorption parameters consisted of dielectric constant, dissipation factor, parallel capacitance, resistance, reactance, impedance and absorbance. It was found that the electrical and absorption properties of fresh cassava tubers and cassava starch were a function of frequency, and there were significant differences between the materials. The dielectric constant, parallel capacitance, resistance and impedance of fresh cassava tubers and cassava starch had similar dramatic decreases with increasing frequency. However, the reactance of both materials increased with an increasing frequency. The electrical parameters of both materials could be classified into two groups. Moreover, the dissipation factor and phase of impedance were the parameters that could be used in the separation of both materials. According to the absorbance patterns of the fresh cassava tubers and cassava starch, there were significant differences.

  17. Optical Absorption and Photo-Thermal Conversion Properties of CuO/H2O Nanofluids.

    PubMed

    Wang, Liangang; Wu, Mingyan; Wu, Daxiong; Zhang, Canying; Zhu, Qunzhi; Zhu, Haitao

    2015-04-01

    Stable CuO/H2O nanofluids were synthesized in a wet chemical method. Optical absorption property of CuO/H2O nanofluids was investigated with hemispheric transmission spectrum in the wavelength range from 200 nm to 2500 nm. Photo-thermal conversion property of the CuO/H2O nanofluids was studied with an evaluation system equipped with an AUT-FSL semiconductor/solid state laser. The results indicate that CuO/H2O nanofluids have strong absorption in visible light region where water has little absorption. Under the irradiation of laser beam with a wavelength of 635 nm and a power of 0.015 W, the temperature of CuO/H2O nanofluids with 1.0% mass fraction increased by 5.6 °C within 40 seconds. Furthermore, the temperature elevation of CuO/H2O nanofluids was proved to increase with increasing mass fractions. On the contrast, water showed little temperature elevation under the identical conditions. The present work shows that the CuO/H2O nanofluids have high potential in the application as working fluids for solar utilization purpose. PMID:26353558

  18. The effect of moisture absorption on the physical properties of polyurethane shape memory polymer foams

    PubMed Central

    Yu, Ya-Jen; Hearon, Keith; Wilson, Thomas S.; Maitland, Duncan J.

    2011-01-01

    The effect of moisture absorption on the glass transition temperature (Tg) and stress/strain behavior of network polyurethane shape memory polymer (SMP) foams has been investigated. With our ultimate goal of engineering polyurethane SMP foams for use in blood contacting environments, we have investigated the effects of moisture exposure on the physical properties of polyurethane foams. To our best knowledge, this study is the first to investigate the effects of moisture absorption at varying humidity levels (non-immersion and immersion) on the physical properties of polyurethane SMP foams. The SMP foams were exposed to differing humidity levels for varying lengths of time, and they exhibited a maximum water uptake of 8.0% (by mass) after exposure to 100% relative humidity for 96 h. Differential scanning calorimetry results demonstrated that water absorption significantly decreased the Tg of the foam, with a maximum water uptake shifting the Tg from 67 °C to 5 °C. Samples that were immersed in water for 96 h and immediately subjected to tensile testing exhibited 100% increases in failure strains and 500% decreases in failure stresses; however, in all cases of time and humidity exposure, the plasticization effect was reversible upon placing moisture-saturated samples in 40% humidity environments for 24 h. PMID:21949469

  19. The influence of recycled expanded polystyrene (EPS) on concrete properties: Influence on flexural strength, water absorption and shrinkage

    NASA Astrophysics Data System (ADS)

    Elsalah, Jamaleddin; Al-Sahli, Yosra; Akish, Ahmed; Saad, Omar; Hakemi, Abdurrahman

    2013-12-01

    Expanded polystyrene waste in a granular form was used as a lightweight aggregate in order to produce lightweight concretë Lightweight EPS concrete composites were produced by replacing the coarse aggregate, either partially or fully with equal volume of EPS aggregates. The coarse aggregate replacements levels used were 25, 50, 75, and 100%, which corresponded to (9.20, 18.40, 27.60, and 36.8%) from total volume. The investigation is directed towards the development and performance evaluation of the concrete composites containing EPS aggregates, without addition of either bonding additives, or super-plasticizers on some concrete properties such as flexure strength, water absorption and change in length (or shrinkage). Experimental results showed that a density reduction of 12% caused flexure strength to decrease by 25.3% at a replacement level of 25% EPS. However, the reduction percentage strongly depends upon the replacement level of EPS granules. Moreover, the lower strength concretes showed a higher water absorption values compared to higher strength concrete, i.e., increasing the volume percentage of EPS increases the water absorption as well as the negative strain (shrinkage). The negative strain was higher at concretes of lower density (containing a high amount of EPS aggregate). The water to cement ratio of EPS aggregate concrete is found to be slightly lower than that of conventional concrete.

  20. Synthesis, Characterization, and Microwave Absorption Properties of Reduced Graphene Oxide/Strontium Ferrite/Polyaniline Nanocomposites.

    PubMed

    Luo, Juhua; Shen, Pan; Yao, Wei; Jiang, Cuifeng; Xu, Jianguang

    2016-12-01

    Strontium ferrite nanoparticles were prepared by a coprecipitation method, and reduced graphene oxide/strontium ferrite/polyaniline (R-GO/SF/PANI) ternary nanocomposites were prepared by in situ polymerization method. The morphology, structure, and magnetic properties of the ternary nanocomposites were investigated by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), TEM, Raman, and VSM. The microwave-absorbing properties of the composites were measured by a vector network analyzer. The XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. TEM photographs reveal that strontium ferrite nanoparticles are uniformly dispersed on the surfaces of R-GO sheets. The R-GO/SF/PANI nanocomposite exhibited the best absorption property with the optimum matching thickness of 1.5 mm in the frequency of 2-18 GHz. The value of the maximum RL was -45.00 dB at 16.08 GHz with the 5.48-GHz bandwidth. The excellent absorption properties of R-GO/SF/PANI nanocomposites indicated their great potential as microwave-absorbing materials. PMID:26969594

  1. Synthesis, Characterization, and Microwave Absorption Properties of Reduced Graphene Oxide/Strontium Ferrite/Polyaniline Nanocomposites.

    PubMed

    Luo, Juhua; Shen, Pan; Yao, Wei; Jiang, Cuifeng; Xu, Jianguang

    2016-12-01

    Strontium ferrite nanoparticles were prepared by a coprecipitation method, and reduced graphene oxide/strontium ferrite/polyaniline (R-GO/SF/PANI) ternary nanocomposites were prepared by in situ polymerization method. The morphology, structure, and magnetic properties of the ternary nanocomposites were investigated by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), TEM, Raman, and VSM. The microwave-absorbing properties of the composites were measured by a vector network analyzer. The XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. TEM photographs reveal that strontium ferrite nanoparticles are uniformly dispersed on the surfaces of R-GO sheets. The R-GO/SF/PANI nanocomposite exhibited the best absorption property with the optimum matching thickness of 1.5 mm in the frequency of 2-18 GHz. The value of the maximum RL was -45.00 dB at 16.08 GHz with the 5.48-GHz bandwidth. The excellent absorption properties of R-GO/SF/PANI nanocomposites indicated their great potential as microwave-absorbing materials.

  2. Zinc Absorption by Young Adults from Supplemental Zinc Citrate Is Comparable with That from Zinc Gluconate and Higher than from Zinc Oxide123

    PubMed Central

    Wegmüller, Rita; Tay, Fabian; Zeder, Christophe; Brnić, Marica; Hurrell, Richard F.

    2014-01-01

    The water-soluble zinc salts gluconate, sulfate, and acetate are commonly used as supplements in tablet or syrup form to prevent zinc deficiency and to treat diarrhea in children in combination with oral rehydration. Zinc citrate is an alternative compound with high zinc content, slightly soluble in water, which has better sensory properties in syrups but no absorption data in humans. We used the double-isotope tracer method with 67Zn and 70Zn to measure zinc absorption from zinc citrate given as supplements containing 10 mg of zinc to 15 healthy adults without food and compared absorption with that from zinc gluconate and zinc oxide (insoluble in water) using a randomized, double-masked, 3-way crossover design. Median (IQR) fractional absorption of zinc from zinc citrate was 61.3% (56.6–71.0) and was not different from that from zinc gluconate with 60.9% (50.6–71.7). Absorption from zinc oxide at 49.9% (40.9–57.7) was significantly lower than from both other supplements (P < 0.01). Three participants had little or no absorption from zinc oxide. We conclude that zinc citrate, given as a supplement without food, is as well absorbed by healthy adults as zinc gluconate and may thus be a useful alternative for preventing zinc deficiency and treating diarrhea. The more insoluble zinc oxide is less well absorbed when given as a supplement without food and may be minimally absorbed by some individuals. This trial was registered at clinicaltrials.gov as NCT01576627. PMID:24259556

  3. Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide.

    PubMed

    Wegmüller, Rita; Tay, Fabian; Zeder, Christophe; Brnic, Marica; Hurrell, Richard F

    2014-02-01

    The water-soluble zinc salts gluconate, sulfate, and acetate are commonly used as supplements in tablet or syrup form to prevent zinc deficiency and to treat diarrhea in children in combination with oral rehydration. Zinc citrate is an alternative compound with high zinc content, slightly soluble in water, which has better sensory properties in syrups but no absorption data in humans. We used the double-isotope tracer method with (67)Zn and (70)Zn to measure zinc absorption from zinc citrate given as supplements containing 10 mg of zinc to 15 healthy adults without food and compared absorption with that from zinc gluconate and zinc oxide (insoluble in water) using a randomized, double-masked, 3-way crossover design. Median (IQR) fractional absorption of zinc from zinc citrate was 61.3% (56.6-71.0) and was not different from that from zinc gluconate with 60.9% (50.6-71.7). Absorption from zinc oxide at 49.9% (40.9-57.7) was significantly lower than from both other supplements (P < 0.01). Three participants had little or no absorption from zinc oxide. We conclude that zinc citrate, given as a supplement without food, is as well absorbed by healthy adults as zinc gluconate and may thus be a useful alternative for preventing zinc deficiency and treating diarrhea. The more insoluble zinc oxide is less well absorbed when given as a supplement without food and may be minimally absorbed by some individuals. This trial was registered at clinicaltrials.gov as NCT01576627.

  4. Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide.

    PubMed

    Wegmüller, Rita; Tay, Fabian; Zeder, Christophe; Brnic, Marica; Hurrell, Richard F

    2014-02-01

    The water-soluble zinc salts gluconate, sulfate, and acetate are commonly used as supplements in tablet or syrup form to prevent zinc deficiency and to treat diarrhea in children in combination with oral rehydration. Zinc citrate is an alternative compound with high zinc content, slightly soluble in water, which has better sensory properties in syrups but no absorption data in humans. We used the double-isotope tracer method with (67)Zn and (70)Zn to measure zinc absorption from zinc citrate given as supplements containing 10 mg of zinc to 15 healthy adults without food and compared absorption with that from zinc gluconate and zinc oxide (insoluble in water) using a randomized, double-masked, 3-way crossover design. Median (IQR) fractional absorption of zinc from zinc citrate was 61.3% (56.6-71.0) and was not different from that from zinc gluconate with 60.9% (50.6-71.7). Absorption from zinc oxide at 49.9% (40.9-57.7) was significantly lower than from both other supplements (P < 0.01). Three participants had little or no absorption from zinc oxide. We conclude that zinc citrate, given as a supplement without food, is as well absorbed by healthy adults as zinc gluconate and may thus be a useful alternative for preventing zinc deficiency and treating diarrhea. The more insoluble zinc oxide is less well absorbed when given as a supplement without food and may be minimally absorbed by some individuals. This trial was registered at clinicaltrials.gov as NCT01576627. PMID:24259556

  5. High sensitivity of Indian summer monsoon to Middle East dust absorptive properties

    NASA Astrophysics Data System (ADS)

    Jin, Qinjian; Yang, Zong-Liang; Wei, Jiangfeng

    2016-07-01

    The absorptive properties of dust aerosols largely determine the magnitude of their radiative impacts on the climate system. Currently, climate models use globally constant values of dust imaginary refractive index (IRI), a parameter describing the dust absorption efficiency of solar radiation, although it is highly variable. Here we show with model experiments that the dust-induced Indian summer monsoon (ISM) rainfall differences (with dust minus without dust) change from ‑9% to 23% of long-term climatology as the dust IRI is changed from zero to the highest values used in the current literature. A comparison of the model results with surface observations, satellite retrievals, and reanalysis data sets indicates that the dust IRI values used in most current climate models are too low, tending to significantly underestimate dust radiative impacts on the ISM system. This study highlights the necessity for developing a parameterization of dust IRI for climate studies.

  6. Some new progress on the light absorption properties of linear alkyl benzene solvent

    NASA Astrophysics Data System (ADS)

    Yu, Guang-You; Cao, De-Wen; Huang, Ai-Zhong; Yu, Lei; Loh, Chang-Wei; Wang, Wen-Wen; Qian, Zhi-Qiang; Yang, Hai-Bo; Huang, Huang; Xu, Zong-Qiang; Zhu, Xue-Yuan; Xu, Bin; Qi, Ming

    2016-01-01

    Linear alkyl benzene (LAB) will be used as the solvent in a liquid scintillator mixture for the JUNO antineutrino experiment. Its light absorption properties should therefore be understood prior to its effective use in the experiment. Attenuation length measurements at a light wavelength of 430 nm have been performed on samples of LAB prepared for the JUNO experiment. Inorganic impurities in LAB have also been studied for their possibilities of light absorption in our wavelength of interest. In view of a tentative plan by the JUNO collaboration to utilize neutron capture with hydrogen in the detector, we also present in this work a preliminary study on the carbon-hydrogen ratio and the attenuation length of the samples. Supported by China Ministry of Science and Technology(2013CB834300)

  7. High sensitivity of Indian summer monsoon to Middle East dust absorptive properties

    PubMed Central

    Jin, Qinjian; Yang, Zong-Liang; Wei, Jiangfeng

    2016-01-01

    The absorptive properties of dust aerosols largely determine the magnitude of their radiative impacts on the climate system. Currently, climate models use globally constant values of dust imaginary refractive index (IRI), a parameter describing the dust absorption efficiency of solar radiation, although it is highly variable. Here we show with model experiments that the dust-induced Indian summer monsoon (ISM) rainfall differences (with dust minus without dust) change from −9% to 23% of long-term climatology as the dust IRI is changed from zero to the highest values used in the current literature. A comparison of the model results with surface observations, satellite retrievals, and reanalysis data sets indicates that the dust IRI values used in most current climate models are too low, tending to significantly underestimate dust radiative impacts on the ISM system. This study highlights the necessity for developing a parameterization of dust IRI for climate studies. PMID:27465689

  8. Solar energy absorption characteristics and the effects of heat on the optical properties of several coatings

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1981-01-01

    The solar energy absorption characteristics of several high temperature coatings were determined and effects of heat on these coatings were evaluated. Included in the investigation were an electroplated alloy of black chrome and vanadium, electroplated black chrome, and chemically colored 316 stainless steel. Each of the coatings possessed good selective solar energy absorption properties at laboratory ambient temperature. Measured at a temperature of 700 K (800 F), the emittances of black chrome, black chrome vanadium, and colored stainless steel were 0.11, 0.61, and 0.15, respectively. Black chrome and black chrome vanadium did not degrade optically in the presence of high heat (811 K (1000 F)). Chemically colored stainless steel showed slight optical degradation when exposed to moderately high heat (616 K (650 F)0, but showed more severe degradation at exposure temperatures beyond this level. Each of the coatings showed good corrosion resistance to a salt spray environment.

  9. High sensitivity of Indian summer monsoon to Middle East dust absorptive properties.

    PubMed

    Jin, Qinjian; Yang, Zong-Liang; Wei, Jiangfeng

    2016-01-01

    The absorptive properties of dust aerosols largely determine the magnitude of their radiative impacts on the climate system. Currently, climate models use globally constant values of dust imaginary refractive index (IRI), a parameter describing the dust absorption efficiency of solar radiation, although it is highly variable. Here we show with model experiments that the dust-induced Indian summer monsoon (ISM) rainfall differences (with dust minus without dust) change from -9% to 23% of long-term climatology as the dust IRI is changed from zero to the highest values used in the current literature. A comparison of the model results with surface observations, satellite retrievals, and reanalysis data sets indicates that the dust IRI values used in most current climate models are too low, tending to significantly underestimate dust radiative impacts on the ISM system. This study highlights the necessity for developing a parameterization of dust IRI for climate studies. PMID:27465689

  10. Excited state absorption properties of Pt(II) terpyridyl complexes bearing π-conjugated arylacetylides.

    PubMed

    Wang, Xianghuai; Goeb, Sébastien; Ji, Zhiqiang; Castellano, Felix N

    2010-11-18

    The synthesis, photophysics, and excited state absorption properties of three platinum(II) terpyridyl acetylide charge transfer (CT) complexes possessing a lone ancillary ligand systematically varied in phenylacetylide (PA) π-conjugation length, [Pt((t)Bu(3)tpy)([C≡C-C(6)H(4)](n)-H)]ClO(4) (n = 1, 2, 3), are described. Density functional theory (DFT) calculations performed on the ground states of complexes 1, 2, and 3 reveal that their HOMOs reside mainly on the ancillary π-conjugated PA moiety, ranging from 86 to 97%, with LUMOs predominantly centered on the terpyridyl acceptor ligand (91-92%). This electronic structure leads to the production of a triplet ligand-to-ligand CT ((3)LLCT) excited state upon visible light excitation with minor contributions from the corresponding triplet metal-to-ligand CT ((3)MLCT) excited state. Unusually strong red-to-near-IR transient absorptions are produced in the excited states of these molecules following selective long wavelength visible excitation of the low energy CT bands that do not emanate from the terpyridyl radical anion produced in the CT excited state or from an arylacetylide-based triplet intraligand ((3)IL) excited state. The extinction coefficients of these low energy absorption transients were determined using the energy transfer method with anthracene serving as the triplet acceptor. A detailed theoretical investigation using DFT and TDDFT methods reveals that these intense near-IR transient absorptions involve transitions resulting from transient oxidation of the PA subunit. In essence, the production of the (3)LLCT excited state transiently oxidizes the PA moiety by one electron, producing the corresponding highly absorbing radical cation-like species, analogous to that experienced in related intramolecular photoinduced electron transfer reactions. The computational work successfully predicts the oscillator strength and peak wavelength of the measured excited state absorption transients across this series

  11. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

    Radio absorptivity data for the Venus middle atmosphere (1 to 6 atm, temperatures from 500 to 575K) obtained from spacecraft radio occultation experiments (at 3.6 to 13.4 cm wavelengths) and earth-based radio astronomical observations (1 to 3 cm wavelength range) are compared to laboratory observations at the latter wavelength range under simulated Venus conditions to infer abundances of microwave-absorbing atmospheric constituents, i.e. H2SO4 in a CO2 atmosphere.

  12. Effect of phytoplankton community composition and cell size on absorption properties in eutrophic shallow lakes: field and experimental evidence.

    PubMed

    Zhang, Yunlin; Yin, Yan; Wang, Mingzhu; Liu, Xiaohan

    2012-05-21

    We investigated phytoplankton absorption properties of Lake Taihu, in the spring and summer of 2005 and 2006, and for 17 days studied laboratory cultures of Scenedesmus obliquus (chlorophyta) and Microcystis aeruginosa (cyanophyta) to determine the effect of phytoplankton community composition and cell size on the absorption properties. There were significant seasonal differences in phytoplankton community composition and absorption coefficients. In spring, the phytoplankton community was dominated by chlorophyta with large cells, whereas in summer was dominated by cyanophyta with small cells. Phytoplankton absorption coefficients increased significantly from spring to summer, with the increase in chlorophyll a (Chla) concentration. In addition, Chla-specific absorption coefficients increased with the phytoplankton community succession from chlorophyta to cyanophyta. In culture, the cells density of S. obliquus was generally lower than that of M. aeruginosa, and Chla concentrations of S. obliquus were significantly higher than those of M. aeruginosa. Correspondingly, the Chla-specific absorption coefficients of S. obliquus were significantly lower than those of M. aeruginosa. Significant exponential correlations were found between absorption and Chla-specific absorption coefficients and Chla concentration for S. obliquus and M. aeruginosa. In addition, we developed a model to predict absorption and Chla-specific absorption coefficients using Chla concentration and cell size when data from two species was grouped together. Field and experimental results both showed that the Chla-specific absorption coefficients of cyanophyta were significantly higher than those of chlorophyta. The variability in specific absorption can attributed to phytoplankton community composition, cell size and pigment composition. As phytoplankton community composition changed significantly with season in the lake, and as variation in the cell sizes and accessory pigments of the phytoplankton

  13. Microwave Absorption Properties of β-SiC-C Composites with Solid Phase Sintering at X Band

    NASA Astrophysics Data System (ADS)

    Zhou, Zehua; Tan, Shouhong; Jiang, Dongliang; Yi, Yu

    In this paper, by using β-SiC powder as a matrix and mixing different content of C, a series of SiC-C composites with solid phase sintering under different temperature were prepared. The relative density, electrical properties and microwave absorption properties at X band were measured systemically. The microwave absorption mechanisms of the composites were studied comprehensively by the test results, together with the microstructure and composition analysis. The main results show that the composites are good microwave absorption ceramics at X band because of the good interface's match of wave impedance by the control of properties and process, C content and sintering process influence effectively all test properties. For the SiC-3wt%C composites (which is the best microwave absorption one) under 2200° sintering, the biggest microwave attenuation is -40.5 dB and almost all attenuations are above -30 dB in the whole X band.

  14. Laboratory Evaluation and Application of Microwave Absorption Properties Under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1997-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurements completed under this grant (NAGW-533), have shown that the opacity from, SO2 under simulated Venus conditions is best described by a different lineshape than was previously used in theoretical predictions. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  15. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1992-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. The goal of this investigation was to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  16. Laboratory Evaluation and Application of Microwave Absorption Properties under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    2005-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth- based or spacecraft-based radio astronomical (emission) observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or the use of laboratory measurements of such properties taken under environmental conditions that are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. For example, new laboratory measurements completed recently by Mohammed and Steffes (2003 and 2004) under this grant (NAG5-12122,5/1/02-4/30/05), have shown that the millimeter-wavelength opacities from both gaseous phosphine (PH3) and gaseous ammonia ("3) under simulated conditions for the outer planets vary significantly from that predicted by theory over a wide range of temperatures and pressures. These results have directly impacted planning and scientific goals for study of Saturn's atmosphere with the Cassini Radio Science Experiment, as discussed below. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both spacecraft entry probe and orbiter (or flyby) radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the

  17. Laboratory Evaluation and Application of Microwave Absorption Properties Under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1998-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties taken under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. For example, laboratory measurements completed recently by Kolodner and Steffes (ICARUS 132, pp. 151-169, March 1998, attached as Appendix A) under this grant (NAGS-4190), have shown that the opacity from gaseous H2SO4 under simulated Venus conditions is best described by a different formalism than was previously used. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both spacecraft entry probe and orbiter radio occultation experiments and by radio astronomical observations, and over a range of frequencies which correspond to those used in such experiments, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  18. Laboratory Evaluation and Application of Microwave Absorption Properties under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    2002-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth-based or spacecraft-based radio astronomical (emission) observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or the use of laboratory measurements of such properties taken under environmental conditions that are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurements have shown that the centimeter-wavelength opacity from gaseous phosphine (PH3) under simulated conditions for the outer planets far exceeds that predicted from theory over a wide range of temperatures and pressures. This fundamentally changed the resulting interpretation of Voyager radio occultation data at Saturn and Neptune. It also directly impacts planning and scientific goals for study of Saturn's atmosphere with the Cassini Radio Science Experiment and the Rossini RADAR instrument. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both spacecraft entry probe and orbiter (or flyby) radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations

  19. Comparative absorption of a standardized curcuminoid mixture and its lecithin formulation.

    PubMed

    Cuomo, John; Appendino, Giovanni; Dern, Adam S; Schneider, Erik; McKinnon, Toni P; Brown, Mark J; Togni, Stefano; Dixon, Brian M

    2011-04-25

    The relative absorption of a standardized curcuminoid mixture and its corresponding lecithin formulation (Meriva) was investigated in a randomized, double-blind, crossover human study. Clinically validated dosages were used for both products, and plasma levels of all three major curcuminoids [curcumin (1a), demethoxycurcumin (1b), and bisdemethoxycurcumin (1c)] were evaluated. Total curcuminoid absorption was about 29-fold higher for Meriva than for its corresponding unformulated curcuminoid mixture, but only phase-2 metabolites could be detected, and plasma concentrations were still significantly lower than those required for the inhibition of most anti-inflammatory targets of curcumin. Remarkably, phospholipid formulation increased the absorption of demethoxylated curcuminoids much more than that of curcumin (1a), with significant differences in plasma curcuminoid profile between Meriva and its corresponding unformulated curcuminoid mixture. Thus, the major plasma curcuminoid after administration of Meriva was not curcumin (1a), but demethoxycurcumin (1b), a more potent analogue in many in vitro anti-inflammatory assays. The improved absorption, and possibly also a better plasma curcuminoid profile, might underlie the clinical efficacy of Meriva at doses significantly lower than unformulated curcuminoid mixtures. PMID:21413691

  20. The WO3/WS2 nanostructures: Preparation, characterization and optical absorption properties

    NASA Astrophysics Data System (ADS)

    Cao, Shixiu; Zhao, Cong; Han, Tao; Peng, Lingling

    2016-07-01

    The WO3/WS2 nanostructures were successfully prepared using a two-step hydrothermal/gas phase method. The physical properties of the nanostructures were characterized using XRD, SEM, TEM, UV-visible spectroscopy. The WO3/WS2 nanostructures obtained were coexistence of WO3 and WS2 in the same particle. The WO3/WS2 nanostructures contained a wide and intensive absorption in the UV-visible light region of 245-750 nm, which showed that the WO3/WS2 nanostructures may have a potential application as an UV-visible photocatalyst.

  1. Microporous Co@CoO nanoparticles with superior microwave absorption properties.

    PubMed

    Liu, Tong; Pang, Yu; Zhu, Mu; Kobayashi, Satoru

    2014-02-21

    Nanoporous metal materials with many potential applications have been synthesized by a chemical dealloying approach. The fabrication of nanoporous metal nanoparticles (NPs), however, is still challenging due to the difficulties in producing suitable nanoscale precursors. Herein, nanoporous Co NPs of 31 nm have been successfully prepared by dealloying Co-Al NPs, and surprisingly they possess micropores in a range from 0.7 to 1.7 nm and a large surface area of 50 m(2) g(-1). The crystalline size of the microporous NPs is 2-5 nm. Through the passivation process, the microporous Co NPs covered with CoO (Co@CoO) are generated as a result of the surface oxidation of Co. They exhibit better microwave absorption properties than their nonporous counterpart. An enhanced reflection loss (RL) value of -90.2 dB is obtained for the microporous Co@CoO NPs with a thickness of merely 1.3 mm. The absorption bandwidth corresponding to the RL below -10 dB reaches 7.2 GHz. The microwave absorption mechanism is discussed in terms of micropore morphology, core@shell structure and nanostructure. This novel microporous material may open new routes for designing high performance microwave absorbers.

  2. Dynamics and two-photon absorption properties of chromophore functionalized semiconductor nanoparticles

    NASA Astrophysics Data System (ADS)

    Varaganti, Shankar; Gessesse, Mathias; Obare, Sherine O.; Ramakrishna, Guda

    2009-08-01

    Two photon absorption cross-sections and fluorescence dynamics of Riboflavin, Fluorescein 548, Coumarin 519 and Quinizarin adsorbed onto reactive (TiO2) and non-reactive (ZrO2) semiconductor nanoparticles have been investigated. These dye molecules are chosen because of their inherently different anchoring groups with which they can bind to semiconductor nanoparticles giving a handle to probe the influence of anchoring group as well as molecule-nanoparticle electronic coupling on the two-photon absorption and nonlinear optical properties. Two-photon excited fluorescence technique has been utilized to monitor the two photon absorption cross-sections and the dynamics of singlet states are followed with femto second fluorescence upconversion. Interesting cross-section trends have been observed where the TPA cross-section of chromophore on ZrO2 surface is similar or lower to that of the free dye while the cross-sections seem to be higher on the surface of reactive TiO2 nanoparticle surface. Fluorescence upconversion investigations were able to probe the electronic interactions of the chromophore with semiconductor nanoparticle and also the adsorption of the chromophores on the surface of the nanoparticle.

  3. In vivo percutaneous absorption of boric acid, borax, and disodium octaborate tetrahydrate in humans compared to in vitro absorption in human skin from infinite and finite doses.

    PubMed

    Wester, R C; Hui, X; Hartway, T; Maibach, H I; Bell, K; Schell, M J; Northington, D J; Strong, P; Culver, B D

    1998-09-01

    Literature from the first half of this century report concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10%, in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percentage dose, with flux and permeability constant (Kp) calculated at 0.009 microgram/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percentage of dose, with flux and Kp calculated at 0.009 microgram/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percentage, with flux and Kp calculated at 0.01 microgram/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. In vitro human skin percentage of doses of boric acid absorbed were 1.2 for a 0.05% solution, 0.28 for a 0.5% solution, and 0.70 for a 5.0% solution. These absorption amounts translated into flux values of, respectively, 0.25, 0.58, and 14.58 micrograms/cm2/h and permeability constants (Kp) of 5.0 x 10(-4), 1.2 x 10(-4), and 2.9 x 10(-4) cm/h for the 0.05, 0.5, and 5.0% solutions. The above in vitro doses were at infinite, 1000 microliters/cm2 volume. At 2 microliters/cm2 (the in vivo dosing volume), flux decreased some

  4. Absorption and Fluorescence Properties of Chromophoric Dissolved Organic Matter Produced by Algae.

    PubMed

    Peng, Tong; Lu, Xiao-lan; Su, Rong-guo; Zhang, Dong-mei

    2015-09-01

    Four kinds of diatom (Chaetoceros curvisetus, Phaeodactylum tricornutum, Nitzschia closterium f. minutissima and Navicula halophile) and two kinds of dinoflagellates (Prorocentrum donghaiense and Gymnodinium) were cultured under laboratory conditions. Variations of optical properties of chromophoric dissolved organic matter (CDOM) were studied with absorption and fluorescence excitation-emission matrix spectroscopy(EEM) during growth of marine microalgae in incubation experiment. Absorption spectrum revealed absorption coefficient a(355) (CDOM absorption coefficients at 355 nm) of 6 kinds of marine microalgae above increased by 64.8%, 242.3%, 535.1%, 903.2%, 836% and 196.4%, respectively. Simultaneously, the absorption spectral slope (Sg), determined between 270 and 350 nm, representing the size of molecular weight of CDOM and humic-like composition, decreased by 8.7%, 34.6%, 39.4%, 53.1%, 46.7%, and 35.7%, respectively. Applying parallel factor analysis (PARAFAC) together with EEM got four components of CDOM: C1(Ex/Em=350(260) nm/450 nm), C2 (Ex/Em=260(430) nm/525 nm), C3 (Ex/Em=325 nm/400 nm) and C4(Ex/Em=275 nm/325 nm), which were relative to three humic-like and one protein-like fluorescent components of Nitzschia closterium f. minutissima and Navicula halophile. In incubation experiment, fluorescence intensity of these four components during growth of Nitzschia closterium f. minutissima increased by, respectively, 8.68, 24.9, 7.19 and 39.8 times, and those of Navicula halophile increased by 2.64, 0.07, 4.39 and 12.4 times, respectively. Significant relationships were found between the fluorescence intensity of four components of CDOM, a(355) and Sg. All results demonstrated that both content and molecular weight of CDOM produced by diatom and dinoflagellate studied in incubation experiment increased, but these two parameters changed more obviously of the diatom than those of dinoflagellate; the proportion of humic-like components in the composition of CDOM

  5. Absorption and Fluorescence Properties of Chromophoric Dissolved Organic Matter Produced by Algae.

    PubMed

    Peng, Tong; Lu, Xiao-lan; Su, Rong-guo; Zhang, Dong-mei

    2015-09-01

    Four kinds of diatom (Chaetoceros curvisetus, Phaeodactylum tricornutum, Nitzschia closterium f. minutissima and Navicula halophile) and two kinds of dinoflagellates (Prorocentrum donghaiense and Gymnodinium) were cultured under laboratory conditions. Variations of optical properties of chromophoric dissolved organic matter (CDOM) were studied with absorption and fluorescence excitation-emission matrix spectroscopy(EEM) during growth of marine microalgae in incubation experiment. Absorption spectrum revealed absorption coefficient a(355) (CDOM absorption coefficients at 355 nm) of 6 kinds of marine microalgae above increased by 64.8%, 242.3%, 535.1%, 903.2%, 836% and 196.4%, respectively. Simultaneously, the absorption spectral slope (Sg), determined between 270 and 350 nm, representing the size of molecular weight of CDOM and humic-like composition, decreased by 8.7%, 34.6%, 39.4%, 53.1%, 46.7%, and 35.7%, respectively. Applying parallel factor analysis (PARAFAC) together with EEM got four components of CDOM: C1(Ex/Em=350(260) nm/450 nm), C2 (Ex/Em=260(430) nm/525 nm), C3 (Ex/Em=325 nm/400 nm) and C4(Ex/Em=275 nm/325 nm), which were relative to three humic-like and one protein-like fluorescent components of Nitzschia closterium f. minutissima and Navicula halophile. In incubation experiment, fluorescence intensity of these four components during growth of Nitzschia closterium f. minutissima increased by, respectively, 8.68, 24.9, 7.19 and 39.8 times, and those of Navicula halophile increased by 2.64, 0.07, 4.39 and 12.4 times, respectively. Significant relationships were found between the fluorescence intensity of four components of CDOM, a(355) and Sg. All results demonstrated that both content and molecular weight of CDOM produced by diatom and dinoflagellate studied in incubation experiment increased, but these two parameters changed more obviously of the diatom than those of dinoflagellate; the proportion of humic-like components in the composition of CDOM

  6. Accuracy of different DFT formalisms for prediction of two-photon absorption properties of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Nayyar, Iffat; Mikhailov, Ivan; Masunov, Artem

    2010-03-01

    The importance of organic molecules with large two-photon absorption (2PA) is realized for deep-tissue fluorescence microscopy, photodynamic therapy, three-dimensional microfabrication and optical data storage. Computer predictions provide understanding of structure/activity relationships and assist in the rational design of polymer materials as an alternative to trial and error methods. In this contribution, we compare various density functional theory (DFT) formalisms to predict two-photon absorption spectra in a series of large donor-acceptor substituted conjugated molecules. We conclude that the accuracy of a posteriori Tamm-Dancoff approximation [1] is close to the exact results obtained in Coupled Electronic Oscillators formalism [2]. Adjusting fraction of exact exchange in XC functionals allow for improved agreement with experiment. [1] Mikhailov, I.A.; Tafur, S.; Masunov, A.E., Phys. Rev. A 77, 01250 (2008) [2] Masunov, A.M.; Tretiak, S., J. Phys. Chem. B 108, 899 (2004)

  7. Microwave absorption property of aligned MWCNT/Fe3O4

    NASA Astrophysics Data System (ADS)

    Hekmatara, H.; Seifi, M.; Forooraghi, K.

    2013-11-01

    This study investigated the microwave absorption properties of magnetic modified multiwall carbon nanotubes (MWCNTs) with different alignments to the electric field (E vector) of the incident electromagnetic (EM) waves. MWCNTs were decorated with Fe3O4 nanoparticles using the wet chemical method and the resulting MWCNT/Fe3O4 was then used as a filler in a MWCNT/Fe3O4/epoxy resin composite at different weight-to-epoxy-resin ratios (2%, 5%, and 8%) with good uniformity and alignment. For each filler concentration, three samples were produced with different alignments of carbon nanotubes using the solution-casting method. For sample one, the nanotube axis (k) was parallel to the E vector of the EM wave, for sample two, k was perpendicular to E, and the third sample contained randomly oriented nanotubes. Magnetic MWCNTs were exposed to a 0.4 T magnetic field in the desired direction to achieve the desired alignment of carbon nanotubes in epoxy resin. Microwave absorption characterization of the considered ranging band (X-band) at all concentrations where the alignment of MWCNT/Fe3O4 was parallel to the incident E vector showed increased absorption. Samples with a perpendicular alignment of MWCNT/Fe3O4 to incident E had the lowest absorption. Samples containing 2 wt% and 8 wt% MWCNT/Fe3O4 aligned parallel to E and had reflection losses exceeding 14.4 dB and 23.6 dB, respectively, over a 10-11 GHz range. The 5 wt% parallel aligned MWCNT/Fe3O4 showed an absorbing peak of 27 dB and a bandwidth broadened to 1.2 GHz.

  8. Comparative Characterization Study of a LaBr3(Ce) Scintillation Crystal in Two Surface Wrapping Scenarios: Absorptive and Reflective

    PubMed Central

    Aldawood, Saad; Castelhano, Ines; Gernhäuser, Roman; Van Der Kolff, Hugh; Lang, Christian; Liprandi, Silvia; Lutter, Rudolf; Maier, Ludwig; Marinšek, Tim; Schaart, Dennis R.; Parodi, Katia; Thirolf, Peter G.

    2015-01-01

    The properties of a 50 mm × 50 mm × 30 mm monolithic LaBr3:Ce scintillator crystal coupled to a position-sensitive multi-anode photomultiplier (PMT, Hamamatsu H9500), representing the absorbing detector of a Compton camera under study for online ion (proton) beam range verification in hadron therapy, was evaluated in combination with either absorptive or reflective crystal surface coating. This study covered an assessment of the energy and position-dependent energy resolution, exhibiting a factor of 2.5–3.5 improvement for the reflectively wrapped crystal at 662 keV. The spatial dependency was investigated using a collimated 137Cs source, showing a steep degradation of the energy resolution at the edges and corners of the absorptively wrapped crystal. Furthermore, the time resolution was determined to be 273 ps (FWHM) and 536 ps (FWHM) with reflective and absorptive coating, respectively, using a 60Co source. In contrast, the light spread function (LSF) of the light amplitude distribution on the PMT segments improved for the absorptively wrapped detector. Both wrapping modalities showed almost no differences in the energy-dependent photopeak detection efficiency. PMID:26697405

  9. Comparative Characterization Study of a LaBr3(Ce) Scintillation Crystal in Two Surface Wrapping Scenarios: Absorptive and Reflective.

    PubMed

    Aldawood, Saad; Castelhano, Ines; Gernhäuser, Roman; Van Der Kolff, Hugh; Lang, Christian; Liprandi, Silvia; Lutter, Rudolf; Maier, Ludwig; Marinšek, Tim; Schaart, Dennis R; Parodi, Katia; Thirolf, Peter G

    2015-01-01

    The properties of a 50 mm × 50 mm × 30 mm monolithic LaBr3:Ce scintillator crystal coupled to a position-sensitive multi-anode photomultiplier (PMT, Hamamatsu H9500), representing the absorbing detector of a Compton camera under study for online ion (proton) beam range verification in hadron therapy, was evaluated in combination with either absorptive or reflective crystal surface coating. This study covered an assessment of the energy and position-dependent energy resolution, exhibiting a factor of 2.5-3.5 improvement for the reflectively wrapped crystal at 662 keV. The spatial dependency was investigated using a collimated (137)Cs source, showing a steep degradation of the energy resolution at the edges and corners of the absorptively wrapped crystal. Furthermore, the time resolution was determined to be 273 ps (FWHM) and 536 ps (FWHM) with reflective and absorptive coating, respectively, using a (60)Co source. In contrast, the light spread function (LSF) of the light amplitude distribution on the PMT segments improved for the absorptively wrapped detector. Both wrapping modalities showed almost no differences in the energy-dependent photopeak detection efficiency. PMID:26697405

  10. Facilely preparation and microwave absorption properties of Fe{sub 3}O{sub 4} nanoparticles

    SciTech Connect

    Wang, Guiqin; Chang, Yongfeng; Wang, Lifang; Liu, Lidong; Liu, Chao

    2013-03-15

    Highlights: ► A bran-new method is firstly used to fabricate Fe{sub 3}O{sub 4} nanoparticles. ► The detailed analysis of formation mechanism is discussed. ► The electromagnetic absorption properties are defined. ► The effect of nanometer-sized is considered for the excellent microwave absorption. - Abstract: The Fe{sub 3}O{sub 4} nanoparticles were prepared by a novel wet-chemical method which shows its highly synthesizing efficiency and controllability. A possible formation mechanism was also proposed to explain the synthesizing process. X-ray diffraction (XRD) and transmission electron microscope (TEM) were employed and yielded an examination of an average diameter of 77 nm of the as-synthesized Fe{sub 3}O{sub 4} nanoparticles with face-centered cubic structure. Vibrating sample magnetometer (VSM) and vector network analyzer were employed to measure the magnetic property and electromagnetic parameters of the nanoparticles, then reflection losses (RL (dB)) were calculated in the frequency range of 2–18 GHz. A large saturation magnetization (72.36 emu/g) and high coercivity (95 Oe) were determined and indicated that the Fe{sub 3}O{sub 4} nanoparticles own strong magnetic performance. Following simulation results showed that the lowest reflection loss of the sample was −21.2 dB at 5.6 GHz with layer thickness of 6 mm. Effect of nanometer-sized further provided an explanation for the excellent microwave absorption behavior shown by the Fe{sub 3}O{sub 4} nanoparticles.

  11. AeroCom INSITU Project: Comparing modeled and measured aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Andrews, Elisabeth; Schmeisser, Lauren; Schulz, Michael; Fiebig, Markus; Ogren, John; Bian, Huisheng; Chin, Mian; Easter, Richard; Ghan, Steve; Kokkola, Harri; Laakso, Anton; Myhre, Gunnar; Randles, Cynthia; da Silva, Arlindo; Stier, Phillip; Skeie, Ragnehild; Takemura, Toshihiko; van Noije, Twan; Zhang, Kai

    2016-04-01

    AeroCom, an open international collaboration of scientists seeking to improve global aerosol models, recently initiated a project comparing model output to in-situ, surface-based measurements of aerosol optical properties. The model/measurement comparison project, called INSITU, aims to evaluate the performance of a suite of AeroCom aerosol models with site-specific observational data in order to inform iterative improvements to model aerosol modules. Surface in-situ data has the unique property of being traceable to physical standards, which is an asset in accomplishing the overall goal of bettering the accuracy of aerosols processes and the predicative capability of global climate models. Here we compare dry, in-situ aerosol scattering and absorption data from ~75 surface, in-situ sites from various global aerosol networks (including NOAA, EUSAAR/ACTRIS and GAW) with a simulated optical properties from a suite of models participating in the AeroCom project. We report how well models reproduce aerosol climatologies for a variety of time scales, aerosol characteristics and behaviors (e.g., aerosol persistence and the systematic relationships between aerosol optical properties), and aerosol trends. Though INSITU is a multi-year endeavor, preliminary phases of the analysis suggest substantial model biases in absorption and scattering coefficients compared to surface measurements, though the sign and magnitude of the bias varies with location. Spatial patterns in the biases highlight model weaknesses, e.g., the inability of models to properly simulate aerosol characteristics at sites with complex topography. Additionally, differences in modeled and measured systematic variability of aerosol optical properties suggest that some models are not accurately capturing specific aerosol behaviors, for example, the tendency of in-situ single scattering albedo to decrease with decreasing aerosol extinction coefficient. The endgoal of the INSITU project is to identify specific

  12. The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae.

    PubMed

    Blache, Ulrich; Jakob, Torsten; Su, Wanwen; Wilhelm, Christian

    2011-08-01

    Photosynthesis-irradiance (P-E)-curves describe the photosynthetic performance of autotrophic organisms. From these P-E-curves the photosynthetic parameters α-slope, P(max), and E(k) can be deduced which are often used to characterize and to compare different organisms or organisms in acclimation to different environmental conditions. Particularly, for in situ-measurements of P-E curves of phytoplankton the analysis of variable chlorophyll fluorescence proved its potential as a sensitive and rapid method. By using Chlorella vulgaris (Trebouxiophyceae), Nannochloropsis salina (Eustigmatophyceae), Skeletonema costatum and Cyclotella meneghiniana (Bacillariophyceae), the present study investigated the influence of cellular bio-optical properties on the correlation of the photosynthetic parameters derived from fluorescence-based P-E-curves with photosynthetic parameters obtained from the measurement of oxygen evolution. It is demonstrated that small planktonic algae show a wide range of cellular absorptivity which was subject to species-specifity, growth stage and environmental conditions, e.g. nutrient limitation. This variability in bio-optical properties resulted in a great deviation of relative electron transport rates (rETRs) from oxygen-based photosynthesis rates. Thus, the photosynthetic parameters α-slope and P(max) derived from rETRs strongly depend on the specific cellular absorptivity and cannot be used to compare the photosynthetic performance of cells with different optical properties. However, it was shown that E(k) is independent of cellular absorptivity and could be used to compare samples with unknown optical properties. PMID:21571541

  13. The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae.

    PubMed

    Blache, Ulrich; Jakob, Torsten; Su, Wanwen; Wilhelm, Christian

    2011-08-01

    Photosynthesis-irradiance (P-E)-curves describe the photosynthetic performance of autotrophic organisms. From these P-E-curves the photosynthetic parameters α-slope, P(max), and E(k) can be deduced which are often used to characterize and to compare different organisms or organisms in acclimation to different environmental conditions. Particularly, for in situ-measurements of P-E curves of phytoplankton the analysis of variable chlorophyll fluorescence proved its potential as a sensitive and rapid method. By using Chlorella vulgaris (Trebouxiophyceae), Nannochloropsis salina (Eustigmatophyceae), Skeletonema costatum and Cyclotella meneghiniana (Bacillariophyceae), the present study investigated the influence of cellular bio-optical properties on the correlation of the photosynthetic parameters derived from fluorescence-based P-E-curves with photosynthetic parameters obtained from the measurement of oxygen evolution. It is demonstrated that small planktonic algae show a wide range of cellular absorptivity which was subject to species-specifity, growth stage and environmental conditions, e.g. nutrient limitation. This variability in bio-optical properties resulted in a great deviation of relative electron transport rates (rETRs) from oxygen-based photosynthesis rates. Thus, the photosynthetic parameters α-slope and P(max) derived from rETRs strongly depend on the specific cellular absorptivity and cannot be used to compare the photosynthetic performance of cells with different optical properties. However, it was shown that E(k) is independent of cellular absorptivity and could be used to compare samples with unknown optical properties.

  14. Facile Synthesis of Fe3O4/GCs Composites and Their Enhanced Microwave Absorption Properties.

    PubMed

    Jian, Xian; Wu, Biao; Wei, Yufeng; Dou, Shi Xue; Wang, Xiaolin; He, Weidong; Mahmood, Nasir

    2016-03-01

    Graphene has good stability and adjustable dielectric properties along with tunable morphologies, and hence can be used to design novel and high-performance functional materials. Here, we have reported a facile synthesis method of nanoscale Fe3O4/graphene capsules (GCs) composites using the combination of catalytic chemical vapor deposition (CCVD) and hydrothermal process. The resulting composite has the advantage of unique morphology that offers better synergism among the Fe3O4 particles as well as particles and GCs. The microwave-absorbing characteristics of developed composites were investigated through experimentally measured electromagnetic properties and simulation studies based on the transmission line theory, explained on the basis of eddy current, natural and exchange resonance, as well as dielectric relaxation processes. The composites bear minimum RL value of -32 dB at 8.76 GHz along with the absorption bandwidth range from 5.4 to 17 GHz for RL lower than -10 dB. The better performance of the composite based on the reasonable impedance characteristic, existence of interfaces around the composites, and the polarization of free carriers in 3D GCs that make the as-prepared composites capable of absorbing microwave more effectively. These results offer an effective way to design high-performance functional materials to facilitate the research in electromagnetic shielding and microwave absorption. PMID:26890224

  15. Synthesis, dual-nonlinear magnetic resonance and microwave absorption properties of nanosheet hierarchical cobalt particles.

    PubMed

    Wen, S L; Liu, Y; Zhao, X C; Cheng, J W; Li, H

    2014-09-14

    In this paper, we report the synthesis of three kinds of novel nanosheet hierarchical cobalt particles by adjusting the [C4H4O6](2-)/Co(2+) ratio through a liquid reduction method. We investigated the electromagnetic properties of the cobalt particles in detail over the microwave frequency range of 1-18 GHz. The results show that the real part of the permittivity decreases and the imaginary part of the permeability increases with an increase in the [C4H4O6](2-)/Co(2+) ratio. The permeability displays two resonance peaks over the frequency range. The cobalt particles with [C4H4O6](2-)/Co(2+) = 6 have a maximum reflection loss of -48.03 dB at 13.61 GHz, and the effective absorption bandwidth (RL ≤ -10 dB) is 6.76 GHz corresponding to a thickness of 1.7 mm. Considering the impedance matching and attenuation based on the electromagnetic parameters, we designed a way to obtain cobalt particles with excellent microwave absorption properties by decreasing the real part of permittivity and increasing the imaginary part of permeability.

  16. Facile Synthesis of Fe3O4/GCs Composites and Their Enhanced Microwave Absorption Properties.

    PubMed

    Jian, Xian; Wu, Biao; Wei, Yufeng; Dou, Shi Xue; Wang, Xiaolin; He, Weidong; Mahmood, Nasir

    2016-03-01

    Graphene has good stability and adjustable dielectric properties along with tunable morphologies, and hence can be used to design novel and high-performance functional materials. Here, we have reported a facile synthesis method of nanoscale Fe3O4/graphene capsules (GCs) composites using the combination of catalytic chemical vapor deposition (CCVD) and hydrothermal process. The resulting composite has the advantage of unique morphology that offers better synergism among the Fe3O4 particles as well as particles and GCs. The microwave-absorbing characteristics of developed composites were investigated through experimentally measured electromagnetic properties and simulation studies based on the transmission line theory, explained on the basis of eddy current, natural and exchange resonance, as well as dielectric relaxation processes. The composites bear minimum RL value of -32 dB at 8.76 GHz along with the absorption bandwidth range from 5.4 to 17 GHz for RL lower than -10 dB. The better performance of the composite based on the reasonable impedance characteristic, existence of interfaces around the composites, and the polarization of free carriers in 3D GCs that make the as-prepared composites capable of absorbing microwave more effectively. These results offer an effective way to design high-performance functional materials to facilitate the research in electromagnetic shielding and microwave absorption.

  17. Electromagnetic properties and microwave absorption of W-type hexagonal ferrites doped with La 3+

    NASA Astrophysics Data System (ADS)

    Deng, Lianwen; Ding, Li; Zhou, Kesheng; Huang, Shengxiang; Hu, Zhaowen; Yang, Bingchu

    2011-07-01

    W-type barium hexaferrites with compositions of Ba 1Co 0.9Zn 1.1Fe 16O 27 and Ba 0.8La 0.2Co 0.9Zn 1.1Fe 16O 27 were synthesized by the sol-gel method. The electromagnetic properties and microwave absorption behavior of these two ferrites were studied in the 2-18 GHz frequency range. The microstructure and morphology of the ferrites were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. The complex permittivity spectra, the complex permeability spectra and microwave reflection loss were measured by a microwave vector network analyzer. The XRD patterns show that the main phase of the Co 2W ferrite forms without other intermediate phases when calcined at 1200 °C. The SEM images indicate that flake-like hexagonal crystals distribute uniformly in the materials. Both the magnetic and dielectric losses are significantly enhanced by partial substitution of La 3+ for Ba 2+ in the W-type barium hexaferrites. The microwave absorption property of the La 3+ doping W-type hexaferrite sample is enhanced with the bandwidth below -10 dB around 8 GHz and the peak value of reflection loss about -39.6 dB at the layer thickness of 2 mm.

  18. Solvothermal Synthesis of Caesium Tungsten Bronze in the Presence of Various Organic Acids and Its NIR Absorption Properties

    NASA Astrophysics Data System (ADS)

    Guo, Chongshen; Yin, Shu; Adachi, Kenji; Chonan, Takeshi; Sato, Tsugio

    2011-10-01

    Nanoparticles of caesium tungsten bronze were successfully synthesized by solvothermal reactions in ethanol with the introduction of different organic fatty acids with various carbon numbers of 1 to 5. Compared to the sample prepared in pure ethanol, the samples obtained by mixed solvent of ethanol and fatty acids showed higher production yield, smaller particle size, more uniform particles size distribution and higher Cs/W atomic ratio. In addition, all of samples obtained using acids-ethanol mixed solvent exhibited higher visible light transmittance and greater NIR absorption performance, indicating the potential application for smart window and heat-ray shielding materials. The addition of acetic acid showed the best performance to facilitate the formation of well dispersed CsxWO3 regular nanorods, leading to its excellent optical properties.

  19. Preparation of Ni-B Coating on Carbonyl Iron and Its Microwave Absorption Properties in the X Band

    NASA Astrophysics Data System (ADS)

    Li, Rong; Zhou, Wan-Cheng; Qing, Yu-Chang

    2014-09-01

    Ni-B coated carbonyl iron particles (CI@Ni-B) are prepared by the electroless plating technique. The structure, morphology, and antioxidant properties of the CI@Ni-B particles are analyzed. The results demonstrate that the CI particles have been coated with intact spherical-shell Ni-B coating, indicating the core-shell structure of CI@Ni-B particles, and the Ni-B coating can prevent the further oxidation of the CI particles. Compared with the raw CI particles/paraffin coatings with the same coating thickness of 2.0 mm and particles content of 70%, the CI@Ni-B particles/paraffin coatings possess higher microwave absorption (the RL exceeding -10 dB is obtained in the whole X band (8.2-12.4 GHz) with minimal RL of -35.0 dB at 9.2 GHz).

  20. A comparative study of intervening and associated H I 21-cm absorption profiles in redshifted galaxies

    NASA Astrophysics Data System (ADS)

    Curran, S. J.; Duchesne, S. W.; Divoli, A.; Allison, J. R.

    2016-08-01

    The star-forming reservoir in the distant Universe can be detected through H I 21-cm absorption arising from either cool gas associated with a radio source or from within a galaxy intervening the sight-line to the continuum source. In order to test whether the nature of the absorber can be predicted from the profile shape, we have compiled and analysed all of the known redshifted (z ≥ 0.1) H I 21-cm absorption profiles. Although between individual spectra there is too much variation to assign a typical spectral profile, we confirm that associated absorption profiles are, on average, wider than their intervening counterparts. It is widely hypothesised that this is due to high velocity nuclear gas feeding the central engine, absent in the more quiescent intervening absorbers. Modelling the column density distribution of the mean associated and intervening spectra, we confirm that the additional low optical depth, wide dispersion component, typical of associated absorbers, arises from gas within the inner parsec. With regard to the potential of predicting the absorber type in the absence of optical spectroscopy, we have implemented machine learning techniques to the 55 associated and 43 intervening spectra, with each of the tested models giving a ≳80% accuracy in the prediction of the absorber type. Given the impracticability of follow-up optical spectroscopy of the large number of 21-cm detections expected from the next generation of large radio telescopes, this could provide a powerful new technique with which to determine the nature of the absorbing galaxy.

  1. A comparative study of intervening and associated H I 21-cm absorption profiles in redshifted galaxies

    NASA Astrophysics Data System (ADS)

    Curran, S. J.; Duchesne, S. W.; Divoli, A.; Allison, J. R.

    2016-11-01

    The star-forming reservoir in the distant Universe can be detected through H I 21-cm absorption arising from either cool gas associated with a radio source or from within a galaxy intervening the sightline to the continuum source. In order to test whether the nature of the absorber can be predicted from the profile shape, we have compiled and analysed all of the known redshifted (z ≥ 0.1) H I 21-cm absorption profiles. Although between individual spectra there is too much variation to assign a typical spectral profile, we confirm that associated absorption profiles are, on average, wider than their intervening counterparts. It is widely hypothesized that this is due to high-velocity nuclear gas feeding the central engine, absent in the more quiescent intervening absorbers. Modelling the column density distribution of the mean associated and intervening spectra, we confirm that the additional low optical depth, wide dispersion component, typical of associated absorbers, arises from gas within the inner parsec. With regard to the potential of predicting the absorber type in the absence of optical spectroscopy, we have implemented machine learning techniques to the 55 associated and 43 intervening spectra, with each of the tested models giving a ≳ 80 per cent accuracy in the prediction of the absorber type. Given the impracticability of follow-up optical spectroscopy of the large number of 21-cm detections expected from the next generation of large radio telescopes, this could provide a powerful new technique with which to determine the nature of the absorbing galaxy.

  2. Construction of CuS Nanoflakes Vertically Aligned on Magnetically Decorated Graphene and Their Enhanced Microwave Absorption Properties.

    PubMed

    Liu, Panbo; Huang, Ying; Yan, Jing; Yang, Yiwen; Zhao, Yang

    2016-03-01

    Hybrid nanocomposites with enhanced microwave absorption properties have been designed by growing CuS nanoflakes on magnetically decorated graphene, and the effect of special nanostructures on microwave absorption properties has been investigated. The structure of the nanocomposites was characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), N2 adsorption-desorption, and vibrating sample magnetometer (VSM). The influence of cetyltrimethylammonium bromide (CTAB) on the morphology of CuS nanoflakes was also investigated. A possible formation process of the nanocomposites and the mechanism of microwave absorption were explained in detail. As an absorber, the nanocomposites with a filler loading of 20 wt % exhibited enhanced microwave absorption properties due to the special nanostructures, extra void space, and synergistic effect. The maximum reflection loss can reach -54.5 dB at 11.4 GHz, and the absorption bandwidths exceeding -10 dB are 4.5 GHz with a thickness of 2.5 mm, which can be adjusted by the thickness. The results indicate that the hybrid nanocomposites with enhanced microwave absorption properties and lightweight have a promising future in decreasing electromagnetic wave irradiation.

  3. Three-dimensional printed optical phantoms with customized absorption and scattering properties.

    PubMed

    Diep, Phuong; Pannem, Sanjana; Sweer, Jordan; Lo, Justine; Snyder, Michael; Stueber, Gabriella; Zhao, Yanyu; Tabassum, Syeda; Istfan, Raeef; Wu, Junjie; Erramilli, Shyamsunder; Roblyer, Darren

    2015-11-01

    Three-dimensional (3D) printing offers the promise of fabricating optical phantoms with arbitrary geometry, but commercially available thermoplastics provide only a small range of physiologically relevant absorption (µa) and reduced scattering (µs`) values. Here we demonstrate customizable acrylonitrile butadiene styrene (ABS) filaments for dual extrusion 3D printing of tissue mimicking optical phantoms. µa and µs` values were adjusted by incorporating nigrosin and titanium dioxide (TiO2) in the filament extrusion process. A wide range of physiologically relevant optical properties was demonstrated with an average repeatability within 11.5% for µa and 7.71% for µs`. Additionally, a mouse-simulating phantom, which mimicked both the geometry and optical properties of a hairless mouse with an implanted xenograft tumor, was printed using dual extrusion methods. 3D printed tumor optical properties matched the live tumor with less than 3% error at a wavelength of 659 nm. 3D printing with user defined optical properties may provide a viable method for durable optically diffusive phantoms for instrument characterization and calibration.

  4. Three-dimensional printed optical phantoms with customized absorption and scattering properties

    PubMed Central

    Diep, Phuong; Pannem, Sanjana; Sweer, Jordan; Lo, Justine; Snyder, Michael; Stueber, Gabriella; Zhao, Yanyu; Tabassum, Syeda; Istfan, Raeef; Wu, Junjie; Erramilli, Shyamsunder; Roblyer, Darren

    2015-01-01

    Three-dimensional (3D) printing offers the promise of fabricating optical phantoms with arbitrary geometry, but commercially available thermoplastics provide only a small range of physiologically relevant absorption (µa) and reduced scattering (µs`) values. Here we demonstrate customizable acrylonitrile butadiene styrene (ABS) filaments for dual extrusion 3D printing of tissue mimicking optical phantoms. µa and µs` values were adjusted by incorporating nigrosin and titanium dioxide (TiO2) in the filament extrusion process. A wide range of physiologically relevant optical properties was demonstrated with an average repeatability within 11.5% for µa and 7.71% for µs`. Additionally, a mouse-simulating phantom, which mimicked both the geometry and optical properties of a hairless mouse with an implanted xenograft tumor, was printed using dual extrusion methods. 3D printed tumor optical properties matched the live tumor with less than 3% error at a wavelength of 659 nm. 3D printing with user defined optical properties may provide a viable method for durable optically diffusive phantoms for instrument characterization and calibration. PMID:26600987

  5. Electronic properties and absorption spectra of ZnSnP2 using mBJ potential

    NASA Astrophysics Data System (ADS)

    Joshi, Ritu; Ahuja, B. L.

    2015-06-01

    We present the energy bands and density of states of ZnSnP2 using full potential linearized augmented plane wave method with modified Becke Johnson potential. It is found that this compound has a direct band gap of about 2.01 eV at Γ point, which originates from the energy difference between P-3p and Sn-5s states. In addition, we have also calculated absorption spectra in the solar energy range and compared it with that of bulk Si to explore the applicability of ZnSnP2 in photovoltaic and optoelectronic devices.

  6. Absorption Spectroscopy Study of Acid-Base and Metal-Binding Properties of Flavanones

    NASA Astrophysics Data System (ADS)

    Shubina, V. S.; Shatalina, Yu. V.

    2013-11-01

    We have used absorption spectroscopy to study the acid-base and metal-binding properties of two structurally similar flavanones: taxifolin and naringenin. We have determined the acid dissociation constants for taxifolin (pKa1 = 7.10 ± 0.05, pKa2 = 8.60 ± 0.09, pKa3 = 8.59 ± 0.19, pKa4 = 11.82 ± 0.36) and naringenin (pKa1 = 7.05 ± 0.05, pKa2 = 8.85 ± 0.09, pKa3 = 12.01 ± 0.38). The appearance of new absorption bands in the visible wavelength region let us determine the stoichiometric composition of the iron (II) complexes of the flavanones. We show that at pH 5, in solution there is a mixture of complexes between taxifolin and iron (II) ions in stoichiometric ratio 2:1 and 1:2, while at pH 7.4 and pH 9, we detect a 1:1 taxifolin:Fe(II) complex. We established that at these pH values, naringenin forms a 2:1 complex with iron (II) ions. We propose structures for the complexes formed. Comprehensive study of the acid-base properties and the metal-binding capability of the two structurally similar flavanones let us determine the structure-properties relation and the conditions under which antioxidant activity of the polyphenols appears, via chelation of variable-valence metal ions.

  7. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1992-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. For example, laboratory measurements performed by Fahd and Steffes have shown that the opacity from gaseous SO2 under simulated Venus conditions can be well described by the Van Vleck-Weisskopf lineshape at wavelengths shortward of 2 cm, but that the opacity of wavelengths greater than 2 cm is best described by a different lineshape that was previously used in theoretical predictions. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  8. Electromagnetic Wave Absorption Property of Graphene with FeO4 Nanoparticles.

    PubMed

    Yang, Cheng; Dai, Shenglong; Zhang, Xiaoyan; Zhao, Tianyu; Yan, Shaojiu; Zhao, Xiuying

    2016-02-01

    Nanomaterials consisting of various ratios of Fe3O4 and graphene (defined C-Fe3O4/GR) were pre- pared by an in situ coordination complex hydro-thermal synthesis method. The structure and morphology of the nanomaterials C-Fe3O4/GR obtained were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). It was found that the Fe3O4 nanoparticles distributed on the surfaces of graphene, and had a spinel structure and a uniform chemical phase when the weight ratios of Fe3O4 to graphene oxide (GO) were 9:1 or 9:2. It was suggested that GO had been successfully reduced to graphene and the Fe3O4 nanoparticles were chemically bonded to graphene. The SQUID vibrating sample magnetometer (SQUID-VSM) indicated that the maximum of the saturation magnetization was 83.6 emmicro g(-1) when the mass ratio of Fe3O4 to GO was 9:2. Electromagnetic wave absorption showed that the chemical compound of Fe3O4 and graphene had a better electromagnetic property than the mechanical blend of Fe3O4 and graphene (M-Fe3O4/GR). The C-Fe3O4/GR had a reflection loss larger than -10 dB in the frequency range 12.9-17.0 GHz for an absorber thickness of 3 mm, and a maximum reflection loss of -12.3 dB at 14.8 GHz and a maximum reflection loss of -31.2 dB at 10.5 GHz for an absorber thickness of 10 mm. Theoretical analysis showed that the electromagnetic wave absorption behavior obeyed the quarter-wave principles. These results showed that the C-Fe3O4/GR nanomaterials can meet the requirements for some engineering applications, showing great application potential in electromagnetic wave absorption.

  9. Kenaf/recycled Jute Natural Fibers Unsaturated Polyester Composites: Water Absorption/dimensional Stability and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Osman, Ekhlas A.; Vakhguelt, Anatoli; Sbarski, Igor; Mutasher, Saad A.

    2012-03-01

    Effects of water absorption on the flexural properties of kenaf-unsaturated polyester composites and kenaf/recycled jute-unsaturated polyester composites were investigated. In the hybrid composites, the total fiber content was fixed to 20 wt%. In this 20 wt%, the addition of jute fiber varied from 0 to 75%, with increment of 25%. The result demonstrates the water absorption and the thickness swelling increased with increase in immersion time. Effects of water absorption on flexural properties of kenaf fiber composites can be reduced significantly with incorporation of recycled jute in composites formulation. The process of absorption of water was found to approach Fickian diffusion behavior for both kenaf composites and hybrid composites.

  10. Validation study of the SeaWiFS oxygen A-band absorption correction: comparing the retrieved cloud optical thicknesses from SeaWiFS measurements.

    PubMed

    Wang, M

    1999-02-20

    Atmospheric correction in ocean-color remote sensing corrects more than 90% of signals in the visible contributed from the atmosphere measured at satellite altitude. The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) atmospheric correction uses radiances measured at two near-infrared wavelengths centered at 765 and 865 nm to estimate the atmospheric contribution and extrapolate it into the visible range. However, the SeaWiFS 765-nm band, which covers 745-785 nm, completely encompasses the oxygen A-band absorption. The O(2) A-band absorption usually reduces more than 10-15% of the measured radiance at the SeaWiFS 765-nm band. Ding and Gordon [Appl. Opt. 34, 2068-2080 (1995)] proposed a numerical scheme to remove the O(2) A-band absorption effects from the atmospheric correction. This scheme has been implemented in the SeaWiFS ocean-color imagery data-processing system. I present results that demonstrate a method to validate the SeaWiFS 765-nm O(2) A-band absorption correction by analyzing the sensor-measured radiances at 765 and 865 nm taken looking at the clouds over the oceans. SeaWiFS is usually not saturated with cloudy scenes because of its bilinear gain design. Because the optical and radiative properties of water clouds are nearly independent of the wavelengths ranging from 400 to 865 nm, the sensor-measured radiances above the cloud at the two near-infrared wavelengths are comparable. The retrieved cloud optical thicknesses from the SeaWiFS band 7 measurements are compared for cases with and without the O(2) A-band absorption corrections and from the band 8 measurements. The results show that, for air-mass values of 2-5, the current SeaWiFS O(2) A-band absorption correction works reasonably well. The validation method is potentially applicable for in-orbit relative calibration for SeaWiFS and other satellite sensors.

  11. THE JHU-SDSS METAL ABSORPTION LINE CATALOG: REDSHIFT EVOLUTION AND PROPERTIES OF Mg II ABSORBERS

    SciTech Connect

    Zhu Guangtun; Menard, Brice

    2013-06-20

    We present a generic and fully automatic method aimed at detecting absorption lines in the spectra of astronomical objects. The algorithm estimates the source continuum flux using a dimensionality reduction technique and nonnegative matrix factorization, and then detects and identifies metal absorption lines. We apply it to a sample of {approx}10{sup 5} quasar spectra from the Sloan Digital Sky Survey and compile a sample of {approx}40,000 Mg II- and Fe II-absorber systems, spanning the redshift range 0.4 < z < 2.3. The corresponding catalog is publicly available. We study the statistical properties of these absorber systems and find that the rest equivalent width distribution of strong Mg II absorbers follows an exponential distribution at all redshifts, confirming previous studies. Combining our results with recent near-infrared observations of Mg II absorbers, we introduce a new parameterization that fully describes the incidence rate of these systems up to z {approx} 5. We find the redshift evolution of strong Mg II absorbers to be remarkably similar to the cosmic star formation history over 0.4 < z < 5.5 (the entire redshift range covered by observations), suggesting a physical link between these two quantities.

  12. Enhanced microwave absorption properties of CTAB assisted Pr-Cu substituted nanomaterial

    NASA Astrophysics Data System (ADS)

    Sadiq, Imran; Naseem, Shahzad; Riaz, Saira; Khan, Hasan M.; Ashiq, Muhammad Naeem; Hussain, S. Sajjad; Rana, Mazhar

    2016-09-01

    In this study, the rare earth Pr3+and divalent Cu2+ elements substituted Sr1-xPrxMn2Fe16-yCuyO27 (x=0, 0.02, 0.06, 0.1 and y=0, 0.1, 0.3, 0.5) W-type hexagonal ferrites were prepared by Sol-Gel method. TGA and DSC analysis of as prepared material was carried out to confirm the temperature at which required phase can be obtained. The XRD patterns exhibit the single phase for all the samples and the lattice parameters were changed with the additives. The absorption bands at wave number 636 and 554 cm-1 in FTIR spectrum indicate the stretching vibration of metal-oxygen ions which also ratifies the single phase for the prepared material. Microstructural analysis confirms the agglomeration of nanograins which leads to formation of platelet like structure which cause in the enhancement of the microwave absorption properties of material. The minimum reflection loss of -59.8 dB at 9.34 GHz frequency was observed makes the prepared material good candidate to be used in super high frequency application. The attenuation constant and reflectivity results are also in good agreement with minimum reflection losses results.

  13. Enhanced absorption of n-3 fatty acids from emulsified compared with encapsulated fish oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have important nutrition and disease management properties. Presently fish oil (FO) supplementation relies on capsular triglyceride. Flavored emulsified lipid preparations may provide an improved approach to FO del...

  14. Comparative in vitro-in vivo percutaneous absorption of the pesticide propoxur.

    PubMed

    van de Sandt, J J; Meuling, W J; Elliott, G R; Cnubben, N H; Hakkert, B C

    2000-11-01

    In vitro and in vivo skin absorption of the pesticide propoxur (2-isopropoxyphenyl N-methyl carbamate, commercially Baygon(TM) and Unden (TM); log Po/w 1.56, MW 209.2) was investigated. In vivo studies were performed in rats and human volunteers, applying the test compound to the dorsal skin and the volar aspect of the forearm, respectively. In vitro experiments were carried out in static diffusion cells using viable full-thickness skin membranes (rat and human), non-viable epidermal membranes (rat and human) and a perfused-pig-ear model. Percutaneous penetration of propoxur in human volunteers was measured by analysis of its metabolite (2-isopropoxyphenol) in blood and urine; in all other studies radiolabeled propoxur ([ring-U-(14)C]propoxur) was used. In order to allow for direct comparison, experimental conditions were standardized with respect to dose (150 microg propoxur per cm(2)), vehicle (60% aqueous ethanol) and exposure time (4 h). In human volunteers, it was found that approximately 6% of the applied dose was excreted via the urine after 24 h, while the potential absorbed dose (amount applied minus amount washed off) was 23 microg/cm(2). In rats these values were 21% and 88 microg/cm(2), respectively. Data obtained in vitro were almost always higher than those obtained in human volunteers. The most accurate in vitro prediction of the human in vivo percutaneous absorption of propoxur was obtained on the basis of the potential absorbed dose. The absorbed dose and the maximal flux in viable full-thickness skin membranes correlated reasonably well with the human in vivo situation (maximal overestimation by a factor of 3). Epidermal membranes overestimated the human in vivo data up to a factor of 8, but the species-differences observed in vivo were reflected correctly in this model. The data generated in the perfused-pig-ear model were generally intermediate between viable skin membranes and epidermal membranes.

  15. Conjugated polymers with pyrrole as the conjugated bridge: synthesis, characterization, and two-photon absorption properties.

    PubMed

    Li, Qianqian; Zhong, Cheng; Huang, Jing; Huang, Zhenli; Pei, Zhiguo; Liu, Jun; Qin, Jingui; Li, Zhen

    2011-07-14

    The synthesis, one- and two-photon absorption (2PA) and emission properties of two novel pyrrole-based conjugated polymers (P1 and P2) are reported. They emitted strong yellow-green and orange fluorescence with fluorescent quantum yields (Φ) of 46 and 33%, respectively. Their maximal 2PA cross sections (δ) measured by the two-photon-induced fluorescence method using femtosecond laser pulses in THF were 2392 and 1938 GM per repeating unit, respectively, indicating that the 2PA chromophores consisting of the triphenylamine with nonplanar structure as the donor and electron-rich pyrrole as the conjugated bridge could be the effective repeating units to enhance the δ values.

  16. Fluorescence upconversion properties of a class of improved pyridinium dyes induced by two-photon absorption

    NASA Astrophysics Data System (ADS)

    Xu, Guibao; Hu, Dawei; Zhao, Xian; Shao, Zongshu; Liu, Huijun; Tian, Yupeng

    2007-06-01

    We report the fluorescence upconversion properties of a class of improved pyridinium toluene- p-sulfonates having donor- π-acceptor (D- π-A) structure under two-photon excitation at 1064 nm. The experimental results show that both the two-photon excited (TPE) fluorescence lifetime and the two-photon pumped (TPP) energy upconversion efficiency were increased with the enhancement of electron-donating capability of the donor in the molecule. It is also indicated that an overlong alkyl group tends to result in a weakened molecular conjugation, leading to a decreased two-photon absorption (TPA) cross section. By choosing the donor, we can obtain a longest fluorescence lifetime of 837 ps, a highest energy upconversion efficiency of ˜6.1%, and a maximum TPA cross-section of 8.74×10 -48 cm 4 s/photon in these dyes.

  17. Synthesis, Morphology Control and Electromagnetic Wave Absorption Properties of Electrospun FeCo Alloy Nanofibers.

    PubMed

    Lee, Young-In; Jang, Dae-Hwan; Choa, Yong-Ho

    2016-05-01

    Recently, increasing interest has been focused on one-dimensional (1 D) magnetic nanomaterials that have significant anisotropic electromagnetic parameters and size effects that can be used to achieve improved shielding efficiency. In this study, the simple, low-cost and scalable synthesis of FeCo nanofibers is demonstrated by combining an electrospinning process with sequential thermal treatment involving calcination in air followed by reduction in H2 atmosphere. A citric acid has an influence on the morphology of the electrospun product. The as-spun precursor nanofibers are transformed into CoFe2O4 and FeCo phases through the sequential thermal treatment while maintaining the fibrous shapes. To evaluate the electromagnetic (EM) wave-absorbing abilities of the FeCo nanofibers, epoxy matrix composites with the nanofibers are fabricated. The composites show excellent EM wave absorption properties where the power loss of the FeCo nanofibers increased to 20 GHz without any degradation. PMID:27483898

  18. Results of fission products β decay properties measurement performed with a total absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Zakari-Issoufou, A.-A.; Porta, A.; Fallot, M.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Agramunt, J.; Äystö, J.; Bowry, M.; Bui, V. M.; Caballero-Folch, R.; Cano-Ott, D.; Eloma, V.; Estévez, E.; Farrelly, G. F.; Garcia, A.; Gelletly, W.; Gomez-Hornillos, M. B.; Gorlychev, V.; Hakala, J.; Jokinen, A.; Jordan, M. D.; Kankainen, A.; Kondev, F. G.; Martinez, T.; Mendoza, E.; Molina, F.; Moore, I.; Perez, A.; Podolyak, Zs.; Penttilä, H.; Regan, P. H.; Rissanen, J.; Rubio, B.; Weber, C.

    2014-03-01

    β-decay properties of fission products are very important for applied reactor physics, for instance to estimate the decay heat released immediately after the reactor shutdown and to estimate the bar ν flux emitted. An accurate estimation of the decay heat and the bar ν emitted flux from reactors, are necessary for purposes such as reactors operation safety and non-proliferation. In order to improve the precision in the prediction for these quantities, the bias due to the Pandemonium effect affecting some important fission product data has to be corrected. New measurements of fission products β-decay, not sensitive to this effect, have been performed with a Total Absorption Spectrometer (TAS) at the JYFL facility of Jyväskylä. An overview of the TAS technique and first results from the 2009 campaign will be presented.

  19. Development of hybrid cotton/hydrogel yarns with improved absorption properties for biomedical applications.

    PubMed

    Pollini, Mauro; Paladini, Federica; Sannino, Alessandro; Maffezzoli, Alfonso

    2016-06-01

    Hyperhidrosis, or excessive sweating, is an overlooked and potentially disabling symptom, which is often seen in social anxiety disorder. In this work an innovative advanced textile material was developed for application in the management of excessive sweating, preparing a drying yarn providing improved comfort. Hybrid cotton/hydrogel yarns were obtained by combining cotton with superabsorbent hydrogels through an optimization study focused on the achievement of the most promising product in terms of absorption properties and resistance to washings. Swelling and washing tests were performed using different hydrogels, and the effect of an additional crosslinking on the materials was also evaluated by testing different solutions containing Al(3+) and Ca(2+) ions. Scanning electron microscopy and infrared spectroscopy analyses were adopted to characterize morphology and chemical structure of the hydrogels undergoing different production processes. The biocompatibility of the hybrid fabrics was demonstrated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide colorimetric assay (MTT) through the extract method.

  20. Controlled growth of Cu-Ni nanowires and nanospheres for enhanced microwave absorption properties

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxia; Dong, Lifeng; Zhang, Baoqin; Yu, Mingxun; Liu, Jingquan

    2016-03-01

    Copper is a good dielectric loss material but has low stability, whereas nickel is a good magnetic loss material and is corrosion resistant but with low conductivity, therefore Cu-Ni hybrid nanostructures have synergistic advantages as microwave absorption (MA) materials. Different Cu/Ni molar ratios of bimetallic nanowires (Cu13@Ni7, Cu5@Ni5 and Cu7@Ni13) and nanospheres (Cu13@Ni7, Cu5@Ni5 and Cu1@Ni3) have been successfully synthesized via facile reduction of hydrazine under similar reaction conditions, and the morphology can be easily tuned by varying the feed ratio or the complexing agent. Apart from the concentrations of Cu2+ and Ni2+, the reduction parameters are similar for all samples to confirm the effects of the Cu/Ni molar ratio and morphology on MA properties. Ni is incorporated into the Cu-Ni nanomaterials as a shell over the Cu core at low temperature, as proved by XRD, SEM, TEM and XPS. Through the complex relative permittivity and permeability, reflection loss was evaluated, which revealed that the MA capacity greatly depended on the Cu/Ni molar ratio and morphology. For Cu@Ni nanowires, as the molar ratio of Ni shell increased the MA properties decreased accordingly. However, for Cu@Ni nanospheres, the opposite trend was found, that is, as the molar ratio of the Ni shell increased the MA properties increased.

  1. Optimal Weld Parameters, Weld Microstructure, Mechanical Properties, and Hydrogen Absorption: An Effective Analysis

    NASA Astrophysics Data System (ADS)

    Bhattacharya, J.; Pal, T. K.

    2011-10-01

    Weld bead-in-grooves were deposited on low alloy, high strength steel plates (ASTM A 517 Grade "F") with a commercial flux-cored filler wire, Auto-MIG 420, at different welding conditions. Microstructure and mechanical properties of welds were characterized by means of optical microscopy, SEM, TEM, EPMA, microhardness measurements, tensile tests, and Charpy impact tests. Hydrogen content of weld metals in as-weld condition and after exposing in simulated service condition was measured by LECO Gas Analyzer. Microstructure of weld metals consisted primarily of lath martensite with small amount of M-A constituents (Martensite-Austenite alternating layers). For some particular welding conditions, such as higher heat input and lower preheat temperatures etc., acicular ferrite is observed with lath martensite. Welds consisting of acicular ferrite in the microstructure showed improved mechanical properties as well as lower hydrogen absorption. The study provides guidelines for selecting proper welding conditions, which results in lower propensity to absorb hydrogen during service, as well as better mechanical properties. Necessity of post-weld heat treatment processes, which is mainly performed to achieve toughness, may be reduced; consequently saving cost and time of the welding process.

  2. Synthesis, Characterization and Microwave Absorption Properties of Polyaniline/Er-Doped Strontium Ferrite Nanocomposite.

    PubMed

    Luo, Juhua; Wang, Eryong; Xu, Yang

    2016-06-01

    Er-doped strontium ferrite nanopowders (SrEr0.3Fe11.7O19) were prepared by the sol-gel method, and then their composites of PANI/SrEr0.3Fe11.7O19 with 10 wt% and 20 wt% ferrite were prepared by an in-situ polymerization process. The characterization of obtained samples was accomplished by XRD, FT-IR, TEM, VSM, and vector network analyzer techniques. A successful conjugation of ferrite nanoparticles with polyaniline could be indicated by XRD and FT-IR analysis. TEM confirmed the formation of polyaniline packed on strontium ferrite surface. Magnetization measurements showed the substituted Er3+ of Fe3+ on basis site enhanced the magnetic property notably and the content of polyaniline also influenced the magnetic property prominently. PANI/SrEr0.3Fe11.7O19 possessed the best absorption property with the optimum matching thickness of 3 mm in the frequency of 2-18 GHz. The value of the maximum RL was -42.0 dB at 12.0 GHz with the 5.5 GHz bandwidth. PMID:27427670

  3. Synthesis, Characterization and Microwave Absorption Properties of Polyaniline/Er-Doped Strontium Ferrite Nanocomposite.

    PubMed

    Luo, Juhua; Wang, Eryong; Xu, Yang

    2016-06-01

    Er-doped strontium ferrite nanopowders (SrEr0.3Fe11.7O19) were prepared by the sol-gel method, and then their composites of PANI/SrEr0.3Fe11.7O19 with 10 wt% and 20 wt% ferrite were prepared by an in-situ polymerization process. The characterization of obtained samples was accomplished by XRD, FT-IR, TEM, VSM, and vector network analyzer techniques. A successful conjugation of ferrite nanoparticles with polyaniline could be indicated by XRD and FT-IR analysis. TEM confirmed the formation of polyaniline packed on strontium ferrite surface. Magnetization measurements showed the substituted Er3+ of Fe3+ on basis site enhanced the magnetic property notably and the content of polyaniline also influenced the magnetic property prominently. PANI/SrEr0.3Fe11.7O19 possessed the best absorption property with the optimum matching thickness of 3 mm in the frequency of 2-18 GHz. The value of the maximum RL was -42.0 dB at 12.0 GHz with the 5.5 GHz bandwidth.

  4. Modification of acrylic bone cement with mesoporous silica nanoparticles: effects on mechanical, fatigue and absorption properties.

    PubMed

    Slane, Josh; Vivanco, Juan; Meyer, Jill; Ploeg, Heidi-Lynn; Squire, Matthew

    2014-01-01

    Polymethyl methacrylate bone cement is the most common and successful method used to anchor orthopedic implants to bone, as evidenced by data from long-term national joint registries. Despite these successes, mechanical failure of the cement mantle can result in premature failure of an implant which has lead to the development of a variety of techniques aimed at enhancing the mechanical properties of the cement, such as the addition of particulate or fiber reinforcements. This technique however has not transitioned into clinical practice, likely due to problems relating to interfacial particle/matrix adhesion and high cement stiffness. Mesoporous silica nanoparticles (MSNs) are a class of materials that have received little attention as polymer reinforcements despite their potential ability to overcome these challenges. Therefore, the objective of the present study was to investigate the use of mesoporous silica nanoparticles (MSNs) as a reinforcement material within acrylic bone cement. Three different MSN loading ratios (0.5%, 2% and 5% (wt/wt)) were incorporated into a commercially available bone cement and the resulting impact on the cement's static mechanical properties, fatigue life and absorption/elution properties were quantified. The flexural modulus and compressive strength and modulus tended to increase with higher MSN concentration. Conversely, the flexural strength, fracture toughness and work to fracture all significantly decreased with increasing MSN content. The fatigue properties were found to be highly influenced by MSNs, with substantial detrimental effects seen with high MSN loadings. The incorporation of 5% MSNs significantly increased cement's hydration degree and elution percentage. The obtained results suggest that the interfacial adhesion strength between the nanoparticles and the polymer matrix was poor, leading to a decrease in the flexural and fatigue properties, or that adequate dispersion of the MSNs was not achieved. These findings

  5. Organic Aerosols from SÃO Paulo and its Relationship with Aerosol Absorption and Scattering Properties

    NASA Astrophysics Data System (ADS)

    Artaxo, P.; Brito, J. F.; Rizzo, L. V.

    2012-12-01

    The megacity of São Paulo with its 19 million people and 7 million cars is a challenge from the point of view of air pollution. High levels of organic aerosols, PM10, black carbon and ozone and the peculiar situation of the large scale use of ethanol fuel makes it a special case. Little is known about the impact of ethanol on air quality and human health and the increase of ethanol as vehicle fuel is rising worldwide An experiment was designed to physico-chemical properties of aerosols in São Paulo, as well as their optical properties. Aerosol size distribution in the size range of 1nm to 10 micrometers is being measured with a Helsinki University SMPS (Scanning Mobility Particle Sizer), an NAIS (Neutral ion Spectrometer) and a GRIMM OPC (Optical Particle Counter). Optical properties are being measured with a TSI Nephelometer and a Thermo MAAP (Multi Angle Absorption Photometer). A CIMEL sunphotometer from the AERONET network measure the aerosol optical depth. Furthermore, a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS) and an Aerosol Chemical Speciation Monitor (ACSM) are used to real-time VOC analysis and aerosol composition, respectively. The ACSM was operated for 3 months continuosly during teh wintertime of 2012. The measured total particle concentration typically varies between 10,000 and 30,000 cm-3 being the lowest late in the night and highest around noon and frequently exceeding 50,000 cm-3. Clear diurnal patterns in aerosol optical properties were observed. Scattering and absorption coefficients typically range between 20 and 100 Mm-1 at 450 nm, and between 10 to 40 Mm-1 at 637 nm, respectively, both of them peaking at 7:00 local time, the morning rush hour. The corresponding single scattering albedo varies between 0.50 and 0.85, indicating a significant contribution of primary absorbing particles to the aerosol population. During the first month a total of seven new particle formation events were observed with growth rates ranging from 9 to 25

  6. Biomechanical properties of retinal glial cells: comparative and developmental data.

    PubMed

    Lu, Yun-Bi; Pannicke, Thomas; Wei, Er-Qing; Bringmann, Andreas; Wiedemann, Peter; Habermann, Gunnar; Buse, Eberhard; Käs, Josef A; Reichenbach, Andreas

    2013-08-01

    The biomechanical properties of Müller glial cells may have importance in understanding the retinal tissue alterations after retinal surgery with removal of the inner limiting membrane and during the ontogenetic development, respectively. Here, we compared the viscoelastic properties of Müller cells from man and monkey as well as from different postnatal developmental stages of the rat. We determined the complex Young's modulus E = E' + iE″ in a defined range of deforming frequencies (30, 100, and 200 Hz) using a scanning force microscope, where the real part E' reflects the elastic property (energy storage or elastic stiffness) and the imaginary part E″ reflects the viscous property (energy dissipation) of the cells. The viscoelastic properties were similar in Müller cells from man, monkey, and rat. In general, the elastic behavior dominated over the viscous behavior (E' > E″). The inner process of the Müller cell was the softest region, the soma the stiffest (Einnerprocess(')Eglia(')). These relations were also observed during the postnatal development of the rat. It is concluded that, generally, retinal cells display mechanics of elastic solids. In addition, the data indicate that the rodent retina is a reliable model to investigate retinal mechanics and tissue alterations after retinal surgery. During retinal development, neuronal branching and synaptogenesis might be particularly stimulated by the viscoelastic properties of Müller cell processes in the inner plexiform layer.

  7. A method for determination of the absorption and scattering properties interstitially in turbid media

    NASA Astrophysics Data System (ADS)

    Dimofte, Andreea; Finlay, Jarod C.; Zhu, Timothy C.

    2005-05-01

    We have developed a method to quickly determine tissue optical properties (absorption coefficient μa and transport scattering coefficient μ's) by measuring the ratio of light fluence rate to source power along a linear channel at a fixed distance (5 mm) from an isotropic point source. Diffuse light is collected by an isotropic detector whose position is determined by a computer-controlled step motor, with a positioning accuracy of better than 0.1 mm. The system automatically records and plots the light fluence rate per unit source power as a function of position. The result is fitted with a diffusion equation to determine μa and μ's. We use an integrating sphere to calibrate each source-detector pair, thus reducing uncertainty of individual calibrations. To test the ability of this algorithm to accurately recover the optical properties of the tissue, we made measurements in tissue simulating phantoms consisting of Liposyn at concentrations of 0.23, 0.53 and 1.14% (μ's = 1.7-9.1 cm-1) in the presence of Higgins black India ink at concentrations of 0.002, 0.012 and 0.023% (μa = 0.1-1 cm-1). For comparison, the optical properties of each phantom are determined independently using broad-beam illumination. We find that μa and μ's can be determined by this method with a standard (maximum) deviation of 8% (15%) and 18% (32%) for μa and μ's, respectively. The current method is effective for samples whose optical properties satisfy the requirement of the diffusion approximation. The error caused by the air cavity introduced by the catheter is small, except when μa is large (μa > 1 cm-1). We presented in vivo data measured in human prostate using this method.

  8. A method for determination of the absorption and scattering properties interstitially in turbid media.

    PubMed

    Dimofte, Andreea; Finlay, Jarod C; Zhu, Timothy C

    2005-05-21

    We have developed a method to quickly determine tissue optical properties (absorption coefficient mu(a) and transport scattering coefficient mu'(s)) by measuring the ratio of light fluence rate to source power along a linear channel at a fixed distance (5 mm) from an isotropic point source. Diffuse light is collected by an isotropic detector whose position is determined by a computer-controlled step motor, with a positioning accuracy of better than 0.1 mm. The system automatically records and plots the light fluence rate per unit source power as a function of position. The result is fitted with a diffusion equation to determine mu(a) and mu'(s). We use an integrating sphere to calibrate each source-detector pair, thus reducing uncertainty of individual calibrations. To test the ability of this algorithm to accurately recover the optical properties of the tissue, we made measurements in tissue simulating phantoms consisting of Liposyn at concentrations of 0.23, 0.53 and 1.14% (mu'(s) = 1.7-9.1 cm(-1)) in the presence of Higgins black India ink at concentrations of 0.002, 0.012 and 0.023% (mu(a) = 0.1-1 cm(-1)). For comparison, the optical properties of each phantom are determined independently using broad-beam illumination. We find that mu(a) and mu'(s) can be determined by this method with a standard (maximum) deviation of 8% (15%) and 18% (32%) for mu(a) and mu'(s), respectively. The current method is effective for samples whose optical properties satisfy the requirement of the diffusion approximation. The error caused by the air cavity introduced by the catheter is small, except when mu(a) is large (mu(a) > 1 cm(-1)). We presented in vivo data measured in human prostate using this method.

  9. Synthesis of zinc oxide particles coated multiwalled carbon nanotubes: Dielectric properties, electromagnetic interference shielding and microwave absorption

    SciTech Connect

    Song, Wei-Li; Cao, Mao-Sheng; Wen, Bo; Hou, Zhi-Ling; Cheng, Jin; Yuan, Jie

    2012-07-15

    Graphical abstract: A resistor–capacitor model could well describe the relationships between the structure and the dielectric properties, electromagnetic interference shielding and microwave-absorption of the composites in the frequency range of 2–18 GHz. The resonant behavior associated with the multiwalled carbon nanotubes/zinc oxide (MWCNTs/ZnO) interface greatly broadens the absorption band. Highlights: ► ZnO-immobilized on multiwalled carbon nanotubes (MWCNTs/ZnO) have resonant behavior. ► A resistor–capacitor model describes the relation between the structure and properties. ► The composite with 40 wt% MWCNTs/ZnO has good electromagnetic interference shielding. ► Two different types of absorption peaks are found in the MWCNTs/ZnO composites. ► The existence of MWCNTs/ZnO interface broadens the absorption band. -- Abstract: Zinc oxide (ZnO) nanoparticles were coated on the surfaces of multiwalled carbon nanotubes (MWCNTs). High resolution transmission electron microscopy images show that the wurtzite ZnO immobilized on the MWCNTs is single-crystalline with a preferential [0 0 0 2] growth direction. A capacitor was generated by the interface of ZnO and MWCNTs, and a resistor–capacitor model could well describe the relationships between the structure and the dielectric properties, electromagnetic interference shielding and microwave-absorption of the composites in the frequency range of 2–18 GHz. The network built by ZnO-immobilized MWCNTs could contribute to the improvement of electrical properties. Resonant peaks associated with the capacitor formed by the interface were observed in the microwave absorption spectra, which suggest that reflection–loss peaks greatly broadens the absorption bandwidth.

  10. Synthesis of Absorption-Dominant Small Gold Nanorods and Their Plasmonic Properties.

    PubMed

    Jia, Henglei; Fang, Caihong; Zhu, Xiao-Ming; Ruan, Qifeng; Wang, Yi-Xiang J; Wang, Jianfang

    2015-07-01

    Absorption-dominant small Au nanorods with diameters of less than 10 nm are prepared using a facile seed-mediated growth method. The diameters of the small gold nanorods range from 6 to 9 nm, and their lengths vary from 16 to 45 nm. Their aspect ratios can be tailored from 2.7 to 4.7. As a result, the longitudinal plasmon resonance wavelengths are readily tunable from ∼720 nm to ∼830 nm by changing the seed-to-Au(III) molar ratio in the growth solution. The fractions of the scattering in the total extinction of the small Au nanorods are found to be in the range of 0.005 to 0.025 with finite-difference time-domain simulations, confirming that the extinction values of these small Au nanorods are dominantly contributed to by the light absorption. Moreover, the small Au nanorod sample is coated with a dense silica layer for photothermal therapy with three cell lines. It shows improved photothermal therapy performance compared to a large Au nanorod sample for the same cellular Au contents. Our study suggests that small Au nanorods are promising light absorbers and photothermal therapy agents. PMID:26079391

  11. Application of Video Spectral Comparator (absorption spectra) for establishing the chronological order of intersecting printed strokes and writing pen strokes.

    PubMed

    Kaur, Ridamjeet; Saini, Komal; Sood, N C

    2013-06-01

    The sequence of intersecting strokes of laser printers (black, blue, red and green) and typewriter ink (black) with the strokes of gel pen ink, ballpoint pen ink and fountain pen ink (black, blue, red and green) has been determined by studying their absorption spectra. The absorption spectra have been generated for each of the two pure inks (i.e. A and B) and points of their intersections (i.e. A over B and B over A) by using Video Spectral Comparator (VSC-2000-HR). The study was carried out with an assumption that the peak characteristics of spectra from the point of intersection should correspond to the peak characteristics of pure ink which was executed later. It was observed that the absorption spectrum of intersection corresponds with either the laser printer or the typewriter ink stroke, whether these strokes were executed earlier or later than the writing instrument strokes. As the results obtained from the study were negative, the FDEs are advised against the practice of this technique in the examination of the sequence of intersecting strokes for these specified inks. PMID:23601731

  12. Application of Video Spectral Comparator (absorption spectra) for establishing the chronological order of intersecting printed strokes and writing pen strokes.

    PubMed

    Kaur, Ridamjeet; Saini, Komal; Sood, N C

    2013-06-01

    The sequence of intersecting strokes of laser printers (black, blue, red and green) and typewriter ink (black) with the strokes of gel pen ink, ballpoint pen ink and fountain pen ink (black, blue, red and green) has been determined by studying their absorption spectra. The absorption spectra have been generated for each of the two pure inks (i.e. A and B) and points of their intersections (i.e. A over B and B over A) by using Video Spectral Comparator (VSC-2000-HR). The study was carried out with an assumption that the peak characteristics of spectra from the point of intersection should correspond to the peak characteristics of pure ink which was executed later. It was observed that the absorption spectrum of intersection corresponds with either the laser printer or the typewriter ink stroke, whether these strokes were executed earlier or later than the writing instrument strokes. As the results obtained from the study were negative, the FDEs are advised against the practice of this technique in the examination of the sequence of intersecting strokes for these specified inks.

  13. Ultraviolet and infrared absorption spectra of Cr2O3 doped-sodium metaphosphate, lead metaphosphate and zinc metaphosphate glasses and effects of gamma irradiation: a comparative study.

    PubMed

    Marzouk, M A; ElBatal, F H; Abdelghany, A M

    2013-10-01

    The effects of gamma irradiation on spectral properties of Cr2O3-doped phosphate glasses of three varieties, namely sodium metaphosphate, lead metaphosphate and zinc metaphosphate have been investigated. Optical spectra of the undoped samples reveal strong UV absorption bands which are attributed to the presence of trace iron impurities in both the sodium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV near visible bands due to combined absorption of both trace iron impurities and divalent lead ions. The effect of chromium oxide content has been investigated. The three different Cr2O3-doped phosphate glasses reveal spectral visible bands varying in their position and intensity and splitting due to the different field strengths of the Na(+), Pb(2+), Zn(2+) cations, together with the way they are housed in the network and their effects on the polarisability of neighboring oxygens ligands. The effects of gamma irradiation on the optical spectral properties of the various glasses have been compared. The different effects for lead and zinc phosphate are related to the ability of Pb(2+), and Zn(2+) to form additional structural units causing stability of the network towards gamma irradiation. Also, the introduction of the transition metal chromium ions reveals some shielding behavior towards irradiation. Infrared absorption spectra of the three different base phosphate glasses show characteristic vibrations due to various phosphate groups depending on the type of glass and Cr2O3 is observed to slightly affect the IR spectra. Gamma irradiation causes minor variations in some of the intensities of the IR spectra but the main characteristic bands due to phosphate groups remain in their number and position. PMID:23816486

  14. Properties of aqueous nitrate and nitrite from x-ray absorption spectroscopy

    SciTech Connect

    Smith, Jacob W.; Lam, Royce K.; Saykally, Richard J.; Shih, Orion; Rizzuto, Anthony M.; Prendergast, David

    2015-08-28

    Nitrate and nitrite ions are of considerable interest, both for their widespread use in commercial and research contexts and because of their central role in the global nitrogen cycle. The chemistry of atmospheric aerosols, wherein nitrate is abundant, has been found to depend on the interfacial behavior of ionic species. The interfacial behavior of ions is determined largely by their hydration properties; consequently, the study of the hydration and interfacial behavior of nitrate and nitrite comprises a significant field of study. In this work, we describe the study of aqueous solutions of sodium nitrate and nitrite via X-ray absorption spectroscopy (XAS), interpreted in light of first-principles density functional theory electronic structure calculations. Experimental and calculated spectra of the nitrogen K-edge XA spectra of bulk solutions exhibit a large 3.7 eV shift between the XA spectra of nitrate and nitrite resulting from greater stabilization of the nitrogen 1s energy level in nitrate. A similar shift is not observed in the oxygen K-edge XA spectra of NO{sub 3}{sup −} and NO{sub 2}{sup −}. The hydration properties of nitrate and nitrite are found to be similar, with both anions exhibiting a similar propensity towards ion pairing.

  15. Magnetic nanoparticles for power absorption: Optimizing size, shape and magnetic properties

    SciTech Connect

    Gonzalez-Fernandez, M.A.; Torres, T.E.; Andres-Verges, M.; Costo, R.; Presa, P. de la; Serna, C.J.; Morales, M.P.; Marquina, C.; Ibarra, M.R.; Goya, G.F.

    2009-10-15

    We present a study on the magnetic properties of naked and silica-coated Fe{sub 3}O{sub 4} nanoparticles with sizes between 5 and 110 nm. Their efficiency as heating agents was assessed through specific power absorption (SPA) measurements as a function of particle size and shape. The results show a strong dependence of the SPA with the particle size, with a maximum around 30 nm, as expected for a Neel relaxation mechanism in single-domain particles. The SiO{sub 2} shell thickness was found to play an important role in the SPA mechanism by hindering the heat outflow, thus decreasing the heating efficiency. It is concluded that a compromise between good heating efficiency and surface functionality for biomedical purposes can be attained by making the SiO{sub 2} functional coating as thin as possible. - Graphical Abstract: The magnetic properties of Fe{sub 3}O{sub 4} nanoparticles from 5 to 110 nm are presented, and their efficiency as heating agents discussed as a function of particle size, shape and surface functionalization.

  16. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1991-01-01

    Laboratory measurements of microwave and millimeter wave properties of the simulated atmosphere of the outer planets and their satellites has continued. One of the focuses is on the development of a radiative transfer model of the Jovian atmosphere at wavelengths from 1 mm to 10 cm. This modeling effort led to laboratory measurements of the millimeter wave opacity of hydrogen sulfide (H2S) under simulated Jovian conditions. Descriptions of the modeling effort, the Laboratory experiment, and the observations are presented. Correlative studies of measurements with Pioneer-Venus radio occultation measurements with longer wavelength emission measurements have provided new ways for characterizing temporal and spatial variations in the abundance of both gases H2SO4 and SO2, and for modeling their roles in the subcloud atmosphere. Laboratory measurements were conducted on 1.35 cm (and 13 cm) opacity of gaseous SO2 and absorptivity of gaseous SO2 at the 3.2 mm wavelength under simulated Venus conditions. Laboratory measurements were completed on millimeter wave dielectric properties of liquid H2SO4, in order to model the effects of the opacity of the clouds of Venus onto millimeter wave emission spectrum.

  17. Effect of Ce Doping on Microwave Absorption Properties of Pr2Fe17 Alloy

    NASA Astrophysics Data System (ADS)

    Cheng, Lichun; Xiong, Jilei; Zhou, Huaiying; Pan, Shunkang; Huang, Hehua

    2016-02-01

    Ce x Pr2- x Fe17 ( x = 0.0, 0.1, 0.2, 0.3, 0.4) alloy powders were successfully synthesized by arc smelting and a high energy ball milling method. The structure, morphology, magnetic properties and electromagnetic parameters of the powders were studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), a vibrating sample magnetometer (VSM) and a vector network analyzer (VNA), respectively. The results show that the saturation magnetization decreases with an increase of Ce concentration. The minimum absorption peak frequency shifts towards a higher frequency region firstly and then towards a lower frequency region based upon the Ce concentration. The Ce x Pr2- x Fe17 alloys exhibit good microwave absorbing properties. The minimum reflection loss of Ce0.1Pr1.9Fe17 powder is about -13.67 dB at 6.40 GHz, and the frequency bandwidth of RL < -8 dB reaches about 2.24 GHz with a thickness of 1.8 mm.

  18. Mechanical Properties Comparing Composite Fiber Length to Amalgam

    PubMed Central

    Petersen, Richard C.; Liu, Perng-Ru

    2016-01-01

    Photocure fiber-reinforced composites (FRCs) with varying chopped quartz-fiber lengths were incorporated into a dental photocure zirconia-silicate particulate-filled composite (PFC) for mechanical test comparisons with a popular commercial spherical-particle amalgam. FRC lengths included 0.5-mm, 1.0 mm, 2.0 mm, and 3.0 mm all at a constant 28.2 volume percent. Four-point fully articulated fixtures were used according to American Standards Test Methods with sample dimensions of 2×2×50 mm3 across a 40 mm span to provide sufficient Euler flexural bending and prevent top-load compressive shear error. Mechanical properties for flexural strength, modulus, yield strength, resilience, work of fracture, critical strain energy release, critical stress intensity factor, and strain were obtained for comparison. Fiber length subsequently correlated with increasing all mechanical properties, p < 1.1×10−5. Although the modulus was significantly statistically higher for amalgam than all composites, all FRCs and even the PFC had higher values than amalgam for all other mechanical properties. Because amalgams provide increased longevity during clinical use compared to the standard PFCs, modulus would appear to be a mechanical property that might sufficiently reduce margin interlaminar shear stress and strain-related microcracking that could reduce failure rates. Also, since FRCs were tested with all mechanical properties that statistically significantly increased over the PFC, new avenues for future development could be provided toward surpassing amalgam in clinical longevity. PMID:27642629

  19. Mechanical Properties Comparing Composite Fiber Length to Amalgam

    PubMed Central

    Petersen, Richard C.; Liu, Perng-Ru

    2016-01-01

    Photocure fiber-reinforced composites (FRCs) with varying chopped quartz-fiber lengths were incorporated into a dental photocure zirconia-silicate particulate-filled composite (PFC) for mechanical test comparisons with a popular commercial spherical-particle amalgam. FRC lengths included 0.5-mm, 1.0 mm, 2.0 mm, and 3.0 mm all at a constant 28.2 volume percent. Four-point fully articulated fixtures were used according to American Standards Test Methods with sample dimensions of 2×2×50 mm3 across a 40 mm span to provide sufficient Euler flexural bending and prevent top-load compressive shear error. Mechanical properties for flexural strength, modulus, yield strength, resilience, work of fracture, critical strain energy release, critical stress intensity factor, and strain were obtained for comparison. Fiber length subsequently correlated with increasing all mechanical properties, p < 1.1×10−5. Although the modulus was significantly statistically higher for amalgam than all composites, all FRCs and even the PFC had higher values than amalgam for all other mechanical properties. Because amalgams provide increased longevity during clinical use compared to the standard PFCs, modulus would appear to be a mechanical property that might sufficiently reduce margin interlaminar shear stress and strain-related microcracking that could reduce failure rates. Also, since FRCs were tested with all mechanical properties that statistically significantly increased over the PFC, new avenues for future development could be provided toward surpassing amalgam in clinical longevity.

  20. Frequency-domain method for measuring spectral properties in multiple-scattering media: methemoglobin absorption spectrum in a tissuelike phantom

    NASA Astrophysics Data System (ADS)

    Fishkin, Joshua B.; So, Peter T. C.; Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio; Franceschini, Maria Angela

    1995-03-01

    We have measured the optical absorption and scattering coefficient spectra of a multiple-scattering medium (i.e., a biological tissue-simulating phantom comprising a lipid colloid) containing methemoglobin by using frequency-domain techniques. The methemoglobin absorption spectrum determined in the multiple-scattering medium is in excellent agreement with a corrected methemoglobin absorption spectrum obtained from a steady-state spectrophotometer measurement of the optical density of a minimally scattering medium. The determination of the corrected methemoglobin absorption spectrum takes into account the scattering from impurities in the methemoglobin solution containing no lipid colloid. Frequency-domain techniques allow for the separation of the absorbing from the scattering properties of multiple-scattering media, and these techniques thus provide an absolute

  1. Moisture absorption and mechanical properties for high-modulus Pitch 75 graphite-fiber-modified cyanate ester resin laminates

    NASA Astrophysics Data System (ADS)

    Blair, Christopher; Zakrzewski, Jerry

    1992-09-01

    Structural epoxy resins used in the fabrication of composite structures for spacecraft applications absorb significant amounts of water. This moisture absorption results in swelling of the structures during fabrication and assembly and subsequent desorption shrinkage in space. Reduction of this effect will be required for development of dimensionally stable large advanced space structures. In the last several years modified epoxy resins, cyanate esters and cyanate esters/epoxy resins have been developed with lower moisture absorption structures to address this issue. Work has continued for several years on the evaluation of high modulus Pitch 75 laminates made using modified low moisture absorption epoxy and cyanate systems to developed structural and thermophysical data for use in the design of stable structures. This paper describes the evaluation of moisture absorption and mechanical properties of unidirectional and quasi-isotropic Pitch 75 laminates made from selected cyanate esters and cyanate ester-epoxy resins.

  2. Complex permittivity, complex permeability and microwave absorption properties of ferrite polymer composites

    NASA Astrophysics Data System (ADS)

    Abbas, S. M.; Dixit, A. K.; Chatterjee, R.; Goel, T. C.

    2007-02-01

    The complex permittivity ( ɛ'- jɛ″), complex permeability (μ'- jμ″) and microwave absorption properties of ferrite-polymer composites prepared with different ferrite ratios of 50%, 60%, 70% and 80% in polyurethane (PU) matrix have been investigated in X-band (8.2-12.4 GHz) frequency range. The M-type hexaferrite composition BaCo +20.9Fe +20.05Si +40.95Fe +310.1O 19 was prepared by solid-state reaction technique, whereas commercial PU was used to prepare the composites. At higher GHz frequencies, ferrite's permeabilities are drastically reduced, however, the forced conversion of Fe +3 to Fe +2 ions that involves electron hopping, could have increased the dielectric losses in the chosen composition. We have measured complex permittivity and permeability using a vector network analyzer (HP/Agilent model PNA E8364B) and software module 85071. All the parameters ɛ', ɛ″, μ' and μ″ are found to increase with increased ferrite contents. Measured values of these parameters were used to determine the reflection loss at various sample thicknesses, based on a model of a single-layered plane wave absorber backed by a perfect conductor. The composite with 80% ferrite content has shown a minimum reflection loss of -24.5 dB (>99% power absorption) at 12 GHz with the -20 dB bandwidth over the extended frequency range of 11-13 GHz for an absorber thickness of 1.6 mm. The prepared composites can fruitfully be utilized for suppression of electromagnetic interference (EMI) and reduction of radar signatures (stealth technology).

  3. Electromagnetic Wave Absorption Property of Graphene with FeO4 Nanoparticles.

    PubMed

    Yang, Cheng; Dai, Shenglong; Zhang, Xiaoyan; Zhao, Tianyu; Yan, Shaojiu; Zhao, Xiuying

    2016-02-01

    Nanomaterials consisting of various ratios of Fe3O4 and graphene (defined C-Fe3O4/GR) were pre- pared by an in situ coordination complex hydro-thermal synthesis method. The structure and morphology of the nanomaterials C-Fe3O4/GR obtained were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). It was found that the Fe3O4 nanoparticles distributed on the surfaces of graphene, and had a spinel structure and a uniform chemical phase when the weight ratios of Fe3O4 to graphene oxide (GO) were 9:1 or 9:2. It was suggested that GO had been successfully reduced to graphene and the Fe3O4 nanoparticles were chemically bonded to graphene. The SQUID vibrating sample magnetometer (SQUID-VSM) indicated that the maximum of the saturation magnetization was 83.6 emmicro g(-1) when the mass ratio of Fe3O4 to GO was 9:2. Electromagnetic wave absorption showed that the chemical compound of Fe3O4 and graphene had a better electromagnetic property than the mechanical blend of Fe3O4 and graphene (M-Fe3O4/GR). The C-Fe3O4/GR had a reflection loss larger than -10 dB in the frequency range 12.9-17.0 GHz for an absorber thickness of 3 mm, and a maximum reflection loss of -12.3 dB at 14.8 GHz and a maximum reflection loss of -31.2 dB at 10.5 GHz for an absorber thickness of 10 mm. Theoretical analysis showed that the electromagnetic wave absorption behavior obeyed the quarter-wave principles. These results showed that the C-Fe3O4/GR nanomaterials can meet the requirements for some engineering applications, showing great application potential in electromagnetic wave absorption. PMID:27433608

  4. Mechanical, Dielectric, and Microwave-Absorption Properties of Alumina Ceramic Containing Dispersed Ti3SiC2

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Luo, Fa; Su, Jinbu; Zhou, Wancheng; Zhu, Dongmei

    2015-03-01

    Dense Al2O3 ceramics containing dispersed Ti3SiC2 were fabricated by hot-pressed sintering. Effects of Ti3SiC2 content on the mechanical, dielectric, and microwave-absorption properties of the ceramics were investigated. The bulk density, flexural strength, and dielectric constant were enhanced by increasing the Ti3SiC2 content. The complex permittivity increased dramatically when the Ti3SiC2 content was above the percolation threshold. The dielectric performance of the ceramics at high temperatures was also studied. The results revealed increases in both the real and imaginary parts with increasing temperature. Ceramic 2.2 mm thick containing 10% ( w/ w) Ti3SiC2 had the optimum microwave-absorption properties. The absorption bandwidth below -5 dB was in the range 8.2-12.4 GHz with a minimum value of -20 dB at 9.56 GHz. Although the reflection loss increased with the increasing temperature, the ceramic still had favorable microwave-absorption properties throughout the X-band. This study contributes to the development of the microwave absorption materials for high-temperature application.

  5. Calculated absorption and scattering properties of gold nanoparticles of different size, shape, and composition: applications in biological imaging and biomedicine.

    PubMed

    Jain, Prashant K; Lee, Kyeong Seok; El-Sayed, Ivan H; El-Sayed, Mostafa A

    2006-04-13

    The selection of nanoparticles for achieving efficient contrast for biological and cell imaging applications, as well as for photothermal therapeutic applications, is based on the optical properties of the nanoparticles. We use Mie theory and discrete dipole approximation method to calculate absorption and scattering efficiencies and optical resonance wavelengths for three commonly used classes of nanoparticles: gold nanospheres, silica-gold nanoshells, and gold nanorods. The calculated spectra clearly reflect the well-known dependence of nanoparticle optical properties viz. the resonance wavelength, the extinction cross-section, and the ratio of scattering to absorption, on the nanoparticle dimensions. A systematic quantitative study of the various trends is presented. By increasing the size of gold nanospheres from 20 to 80 nm, the magnitude of extinction as well as the relative contribution of scattering to the extinction rapidly increases. Gold nanospheres in the size range commonly employed ( approximately 40 nm) show an absorption cross-section 5 orders higher than conventional absorbing dyes, while the magnitude of light scattering by 80-nm gold nanospheres is 5 orders higher than the light emission from strongly fluorescing dyes. The variation in the plasmon wavelength maximum of nanospheres, i.e., from approximately 520 to 550 nm, is however too limited to be useful for in vivo applications. Gold nanoshells are found to have optical cross-sections comparable to and even higher than the nanospheres. Additionally, their optical resonances lie favorably in the near-infrared region. The resonance wavelength can be rapidly increased by either increasing the total nanoshell size or increasing the ratio of the core-to-shell radius. The total extinction of nanoshells shows a linear dependence on their total size, however, it is independent of the core/shell radius ratio. The relative scattering contribution to the extinction can be rapidly increased by increasing

  6. Eruption combustion synthesis of NiO/Ni nanocomposites with enhanced properties for dye-absorption and lithium storage.

    PubMed

    Wen, Wei; Wu, Jin-Ming

    2011-10-01

    Large-scale energy-efficient productions of oxide nanoparticles are of great importance in energy and environmental applications. In nature, volcano eruptions create large amounts of volcano ashes within a short duration. Inspired by such phenomena, we report herein our first attempt to achieve an artificial volcano for mass productions of various oxide nanoparticles with enhanced properties for energy and environmental applications. The introduction of NaF into the solution combustion synthesis (SCS), which is a generally adopted synthetic route for mass productions of various oxide nanoparticles, results in better particle dispersity and a drastic increase in specific surface area compared to the conventional SCS. In a fixed dosage of NaF, a new eruption combustion pattern emerges, which may be contributed to the more gas evolution, lower apparent density, and weaker interparticle force. The novel eruption combustion pattern observed in SCS provides a versatile alternative for SCS to control combustion behavior, microstructure, and property of the products. NiO/Ni nanocomposite yielded by the new approach shows an ideal dye-absorption ability as well as lithium storage capacity. The new SCS pattern reported in this paper is versatile, emerging in various systems of Ni-Co-O, Co-O, La-O, Ni-Co-O, Zn-Co-O, and La-Ni-O.

  7. Eruption combustion synthesis of NiO/Ni nanocomposites with enhanced properties for dye-absorption and lithium storage.

    PubMed

    Wen, Wei; Wu, Jin-Ming

    2011-10-01

    Large-scale energy-efficient productions of oxide nanoparticles are of great importance in energy and environmental applications. In nature, volcano eruptions create large amounts of volcano ashes within a short duration. Inspired by such phenomena, we report herein our first attempt to achieve an artificial volcano for mass productions of various oxide nanoparticles with enhanced properties for energy and environmental applications. The introduction of NaF into the solution combustion synthesis (SCS), which is a generally adopted synthetic route for mass productions of various oxide nanoparticles, results in better particle dispersity and a drastic increase in specific surface area compared to the conventional SCS. In a fixed dosage of NaF, a new eruption combustion pattern emerges, which may be contributed to the more gas evolution, lower apparent density, and weaker interparticle force. The novel eruption combustion pattern observed in SCS provides a versatile alternative for SCS to control combustion behavior, microstructure, and property of the products. NiO/Ni nanocomposite yielded by the new approach shows an ideal dye-absorption ability as well as lithium storage capacity. The new SCS pattern reported in this paper is versatile, emerging in various systems of Ni-Co-O, Co-O, La-O, Ni-Co-O, Zn-Co-O, and La-Ni-O. PMID:21919510

  8. Comparative study of the absorption spectrum of Li 2CaSiO 4:Cr 4+: First-principles fully relativistic and crystal field calculations

    NASA Astrophysics Data System (ADS)

    Brik, M. G.; Ogasawara, K.

    2007-11-01

    Systematic analysis of the energy level scheme and ground state absorption of the Cr4+ ion in Li2CaSiO4 crystal was performed using the exchange charge model of the crystal field [B.Z. Malkin, in: A.A. Kaplyanskii, B.M. Macfarlane (Eds.), Spectroscopy of Solids Containing Rare-earth Ions, North-Holland, Amsterdam, 1987, pp. 33-50] and recently developed first-principles approach to the analysis of the absorption spectra of impurity ions in crystals based on the discrete variational multielectron (DVME) method [K. Ogasawara, T. Iwata, Y. Koyama, T. Ishii, I. Tanaka, H. Adachi, Phys. Rev. B 64 (2001) 115413]. Using the former method, the values of parameters of crystal field acting on the Cr4+ ion valence electrons were calculated using the Li2CaSiO4 crystal structure data. Energy levels of the Cr4+ ion obtained after diagonalizing the crystal field Hamiltonian are in good agreement with those obtained from the experimental spectra. The latter method is based on the numerical solution of the Dirac equation; therefore, all relativistic effects are automatically considered. As a result, energy level scheme of Cr4+ and its absorption spectra in both polarizations were calculated, assigned and compared with experimental data; energy of the lowest charge transfer transition was evaluated and compared with theoretical predictions for the CrO44- complex available in the literature. The main features of the experimental spectra shape are reproduced well by the calculations. By performing analysis of the molecular orbitals (MO) population, it was shown that the covalent effects play an important role in formation of the spectral properties of Cr4+ ion in the considered crystal.

  9. Finding consistency between different views of the absorption enhancement of black carbon: An observationally constrained hybrid model to support a transition in optical properties with mass fraction

    NASA Astrophysics Data System (ADS)

    Coe, H.; Allan, J. D.; Whitehead, J.; Alfarra, M. R. R.; Villegas, E.; Kong, S.; Williams, P. I.; Ting, Y. C.; Haslett, S.; Taylor, J.; Morgan, W.; McFiggans, G.; Spracklen, D. V.; Reddington, C.

    2015-12-01

    The mixing state of black carbon is uncertain yet has a significant influence on the efficiency with which a particle absorbs light. In turn, this may make a significant contribution to the uncertainty in global model predictions of the black carbon radiative budget. Previous modelling studies that have represented this mixing state using a core-shell approach have shown that aged black carbon particles may be considerably enhanced compared to freshly emitted black carbon due to the addition of co-emitted, weakly absorbing species. However, recent field results have demonstrated that any enhancement of absorption is minor in the ambient atmosphere. Resolving these differences in absorption efficiency is important as they will have a major impact on the extent to which black carbon heats the atmospheric column. We have made morphology-independent measurements of refractory black carbon mass and associated weakly absorbing material in single particles from laboratory-generated diesel soot and black carbon particles in ambient air influenced by traffic and wood burning sources and related these to the optical properties of the particles. We compared our calculated optical properties with optical models that use varying mixing state assumptions and by characterising the behaviour in terms of the relative amounts of weakly absorbing material and black carbon in a particle we show a sharp transition in mixing occurs. We show that the majority of black carbon particles from traffic-dominated sources can be treated as externally mixed and show no absorption enhancement, whereas models assuming internal mixing tend to give the best estimate of the absorption enhancement of thickly coated black carbon particles from biofuel or biomass burning. This approach reconciles the differences in absorption enhancement previously observed and offers a systematic way of treating the differences in behaviour observed.

  10. A Comparative Study of Molecular Structure, pKa, Lipophilicity, Solubility, Absorption and Polar Surface Area of Some Antiplatelet Drugs

    PubMed Central

    Remko, Milan; Remková, Anna; Broer, Ria

    2016-01-01

    Theoretical chemistry methods have been used to study the molecular properties of antiplatelet agents (ticlopidine, clopidogrel, prasugrel, elinogrel, ticagrelor and cangrelor) and several thiol-containing active metabolites. The geometries and energies of most stable conformers of these drugs have been computed at the Becke3LYP/6-311++G(d,p) level of density functional theory. Computed dissociation constants show that the active metabolites of prodrugs (ticlopidine, clopidogrel and prasugrel) and drugs elinogrel and cangrelor are completely ionized at pH 7.4. Both ticagrelor and its active metabolite are present at pH = 7.4 in neutral undissociated form. The thienopyridine prodrugs ticlopidine, clopidogrel and prasugrel are lipophilic and insoluble in water. Their lipophilicity is very high (about 2.5–3.5 logP values). The polar surface area, with regard to the structurally-heterogeneous character of these antiplatelet drugs, is from very large interval of values of 3–255 Å2. Thienopyridine prodrugs, like ticlopidine, clopidogrel and prasugrel, with the lowest polar surface area (PSA) values, exhibit the largest absorption. A high value of polar surface area (PSA) of cangrelor (255 Å2) results in substantial worsening of the absorption in comparison with thienopyridine drugs. PMID:27007371

  11. Synthesis, Characterization, Absorption Spectra, and Luminescence Properties of Organometallic Platinum(II) Terpyridine Complexes.

    PubMed

    Arena, Giuseppe; Calogero, Giuseppe; Campagna, Sebastiano; Monsù Scolaro, Luigi; Ricevuto, Vittorio; Romeo, Raffaello

    1998-06-01

    A series of new organometallic platinum(II) complexes containing terdentate polypyridine ligands has been prepared and characterized. Their absorption spectra in 4:1 (v/v) MeOH/EtOH fluid solution at room temperature and luminescence in the same matrix at 77 K have been investigated. The new species are [Pt(terpy)Ph]Cl (3, terpy = 2,2':6',2"-terpyridine, Ph = phenyl), [Pt(Ph-terpy)Cl]Cl (4, Ph-terpy = 4'-phenyl-2,2':6',2"-terpyridine), [Pt(Ph-terpy)Me]Cl (5), and [Pt(Ph-terpy)Ph]Cl (6). The results have been compared with those for [Pt(terpy)Cl]Cl (1) and [Pt(terpy)Me]Cl (2). NMR data evidence that all the complexes but 3 and 6 oligomerize in solution leading to stacked species. The absorption spectra are dominated by moderately intense metal-to-ligand charge-transfer (MLCT) bands in the visible region and by intense ligand-centered (LC) bands in the UV region. All the compounds are luminescent in a 4:1 (v/v) MeOH/EtOH rigid matrix at 77 K, exhibiting a structured emission within the range 460-600 nm. This feature is assigned to formally (3)LC excited states which receive substantial contribution from closely lying (3)MLCT levels. Complexes 1, 2, 4, and 5 also exhibit a relatively narrow and unstructured luminescence band within the range 680-800 nm, which dominates the luminescence spectrum on increasing concentration and exciting at longer wavelengths. The band is assigned to a dsigma(metal) --> pi(polypyridine) ((3)MMLCT) state, originating from metal-metal interactions occurring in head-to-tail dimers (or polymers). A third broad band is shown by 1 and 4 under all concentration conditions and by 2 and 5 only in concentrated solutions and is attributed to excimeric species originating from pi-pi interactions due to stacking between polypyridine ligands.

  12. Tuning the magnetic property of vacancy-defected graphyne by transition metal absorption

    SciTech Connect

    Bhattacharya, Barnali; Singh, Ngangbam Bedamani; Sarkar, Utpal

    2015-06-24

    In this work, we demonstrate a novel and simple approach to tune the electronic properties as well as magnetic properties of transition metal absorbed in vacancy-defected graphyne (VGY). A double vacancy has been introduced in the graphyne unit and TM atoms (V-Cu) are systematically doped in the vacant site. We find that combination of these two give rise to some interesting spintronics properties such as half-metalicity, and spin-select half-semiconductivity. Furthermore, the magnetic moments of TM absorbed vacancy-defected graphyne are found to be higher compare to TM absorbed graphyne. Although Ni absorbed graphyne is nonmagnetic in nature, we find that the Ni absorbed VGY behaves as half metal with a net magnetic moment of 2 µ{sub B} and can be used as spin filter. Thus, the TM absorbed vacancy-defected graphyne are more suitable candidate for magneto-optics and spintronics.

  13. Scattering and absorption properties of near-surface aerosol over Gangetic-Himalayan region: the role of boundary-layer dynamics and long-range transport

    NASA Astrophysics Data System (ADS)

    Dumka, U. C.; Kaskaoutis, D. G.; Srivastava, M. K.; Devara, P. C. S.

    2015-02-01

    Light scattering and absorption properties of atmospheric aerosols are of vital importance for evaluating their types, sources and radiative forcing. This is of particular interest over the Gangetic-Himalayan (GH) region due to uplift of aerosol from the plains to the Himalayan range, causing serious effects on atmospheric heating, glaciology and monsoon circulation. In this respect, the Ganges Valley Aerosol Experiment (GVAX) was initiated in Nainital from June 2011 to March 2012 with the aim of examining the aerosol properties, source regions, uplift mechanisms and aerosol-radiation-cloud interactions. The present study examines the temporal (diurnal, monthly, seasonal) evolution of scattering (σabsorption (σap) coefficients, their wavelength dependence, and the role of the Indo-Gangetic plains (IGP), boundary-layer dynamics (BLD) and long-range transport (LRT) in aerosol evolution via the Atmospheric Radiation Measurement Mobile Facility. The analysis is separated for particles <10 μm and <1 μm in diameter in order to examine the influence of particle size on optical properties. The σsp and σap exhibit a pronounced seasonal variation between the monsoon low and post-monsoon (November) high, while the scattering wavelength exponent exhibits higher values during the monsoon, in contrast to the absorption Ångström exponent which maximizes in December-March. The elevated-background measuring site provides the advantage of examining the LRT of natural and anthropogenic aerosols from the IGP and southwest Asia and the role of BLD in the aerosol lifting processes. The results reveal higher aerosol concentrations at noontime along with an increase in mixing height, suggesting influence from IGP. The locally emitted aerosols present higher wavelength dependence of the absorption in October-March compared to the rather well-mixed and aged transported aerosols. Monsoon rainfall and seasonally changing air masses contribute to the alteration of the

  14. Preparation and characterization of novel glass-ceramic tile with microwave absorption properties from iron ore tailings

    NASA Astrophysics Data System (ADS)

    Yao, Rui; Liao, SongYi; Dai, ChangLu; Liu, YuChen; Chen, XiaoYu; Zheng, Feng

    2015-03-01

    A novel glass-ceramic tile consisting of one glass-ceramic layer (GC) attaining microwave absorption properties atop ceramic substrate was prepared through quench-heat treatment route derived from iron ore tailings (IOTs) and commercial raw materials (purity range 73-99%). X-ray diffraction (XRD), SEM, Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Physical property measurement system (PPMS) and Vector network analyzer (VNA) measurements were carried out to investigate phase, microstructure, magnetic and microwave absorption aspects of the glass-ceramic layer. Roughly 80.6±1.7 wt% borosilicate glass and 19.4±1.7 wt% spinel ferrite with chemical formula of (Zn2+0.17Fe3+0.83)[Fe3+1.17Fe2+0.06Ni2+0.77]O4 were found among the tested samples. Absorption of Electromagnetic wave by 3 mm thick glass-ceramic layer at frequency of 2-18 GHz reached peak reflection loss (RL) of -17.61 dB (98.27% microwave absorption) at 10.31 GHz. Altering the thickness of the glass-ceramic layer can meet the requirements of different level of microwave absorption.

  15. Broadband optical limiting and nonlinear optical absorption properties of a novel hyperbranched conjugated polymer

    NASA Astrophysics Data System (ADS)

    Li, Chao; Liu, Chunling; Li, Quanshui; Gong, Qihuang

    2004-12-01

    The nonlinear transmittance of a novel hyperbranched conjugated polymer named DMA-HPV has been measured in CHCl 3 solution using a nanosecond optical parametric oscillator. DMA-HPV shows excellent optical limiting performance in the visible region from 490 to 610 nm. An explanation based on the combination of two-photon absorption and reverse saturable absorption was proposed for its huge and broadband nonlinear optical absorption.

  16. Measuring sound absorption properties of porous materials using a calibrated volume velocity source

    NASA Astrophysics Data System (ADS)

    Arenas, Jorge P.; Darmendrail, Luis

    2013-10-01

    Measurement of acoustic properties of sound-absorbing materials has been the source of much investigation that has produced practical measuring methods. In particular, the measurement of the normal incidence sound absorption coefficient is commonly done using a well-known configuration of a tube carrying a plane wave. The sound-absorbing coefficient is calculated from the surface impedance measured on a sample of material. Therefore, a direct measurement of the impedance requires knowing the ratio between the sound pressure and the volume velocity. However, the measurement of volume velocity is not straightforward in practice and many methods have been proposed including complex transducers, laser vibrometry, accelerometers and calibrated volume velocity sources. In this paper, a device to directly measure the acoustic impedance of a sample of sound-absorbing material is presented. The device uses an internal microphone in a small cavity sealed by a loudspeaker and a second microphone mounted in front of this source. The calibration process of the device and the limitations of the method are also discussed and measurement examples are presented. The accuracy of the device was assessed by direct comparison with the standardized method. The proposed measurement method was tested successfully with various types of commercial acoustic porous materials.

  17. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1989-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. Work performed has shown that laboratory measurements of the millimeter-wave opacity of ammonia between 7.5 mm and 9.3 mm and also at the 3.2 mm wavelength require a different lineshape to be used in the theoretical prediction for millimeter-wave ammonia opacity than was previously used. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  18. Development of hybrid cotton/hydrogel yarns with improved absorption properties for biomedical applications.

    PubMed

    Pollini, Mauro; Paladini, Federica; Sannino, Alessandro; Maffezzoli, Alfonso

    2016-06-01

    Hyperhidrosis, or excessive sweating, is an overlooked and potentially disabling symptom, which is often seen in social anxiety disorder. In this work an innovative advanced textile material was developed for application in the management of excessive sweating, preparing a drying yarn providing improved comfort. Hybrid cotton/hydrogel yarns were obtained by combining cotton with superabsorbent hydrogels through an optimization study focused on the achievement of the most promising product in terms of absorption properties and resistance to washings. Swelling and washing tests were performed using different hydrogels, and the effect of an additional crosslinking on the materials was also evaluated by testing different solutions containing Al(3+) and Ca(2+) ions. Scanning electron microscopy and infrared spectroscopy analyses were adopted to characterize morphology and chemical structure of the hydrogels undergoing different production processes. The biocompatibility of the hybrid fabrics was demonstrated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide colorimetric assay (MTT) through the extract method. PMID:27040251

  19. Enhanced microwave absorption properties in cobalt-zinc ferrite based nanocomposites

    NASA Astrophysics Data System (ADS)

    Poorbafrani, A.; Kiani, E.

    2016-10-01

    In an attempt to find a solution to the problem of the traditional spinel ferrite used as the microwave absorber, the Co0.6Zn0.4Fe2O4-Paraffin nanocomposites were investigated. Cobalt-zinc ferrite powders, synthesized through PVA sol-gel method, were combined with differing concentrations of Paraffin wax. The nanocomposite samples were characterized employing various experimental techniques including X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Alternating Gradient Force Magnetometer (AGFM), and Vector Network Analyzer (VNA). The saturation magnetization and coercivity were enhanced utilizing appropriate stoichiometry, coordinate agent, and sintering temperature required for the preparation of cobalt-zinc ferrite. The complex permittivity and permeability spectra, and Reflection Loss (RL) of Co0.6Zn0.4Fe2O4-Paraffin nanocomposites were measured in the frequency range of 1-18 GHz. The microwave absorption properties of nanocomposites indicated that the absorbing composite containing 20 wt% of paraffin manifests the strongest microwave attenuation ability. The composite exhibited the reflection loss less than -10 dB in the whole C-band and 30% of the X-band frequencies.

  20. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1988-01-01

    In the first half of this grant year, laboratory measurements were conducted on the millimeter-wave properties of atmospheric gases under simulated conditions for the outer planet. Significant improvements in the current system have made it possible to accurately characterize the opacity from gaseous NH3 at longer millimeter wavelengths (7 to 10 mm) under simulated Jovian conditions. In the second half of the grant year, it is hoped to extend such measurements to even shorter millimeter-wavelengths. Further analysis and application of the laboratory results to microwave and millimeter-wave absorption data for the outer planets, such as results from Voyager Radio Occultation experiments and earth-based radio astronomical observations will be continued. The analysis of available multispectral microwave opacity data from Venus, including data from the most recent radio astronomical ovservations in the 1.3 to 3.6 cm wavelength range and newly obtained Pioneer-Venus Radio Occulatation measurements at 13 cm, using the laboratory measurements as an interpretative tool will be pursued.

  1. Microwave absorption properties of conducting polymer composite with barium ferrite nanoparticles in 12.4-18 GHz

    NASA Astrophysics Data System (ADS)

    Ohlan, Anil; Singh, Kuldeep; Chandra, Amita; Dhawan, S. K.

    2008-08-01

    Conducting polymer nanocomposites of polyphenyl amine with barium ferrite nanoparticles (50-70nm) have been synthesized via emulsion polymerization. The complex permittivity, permeability, and microwave absorption properties of the composite were studied in the 12.4-18GHz (Ku band) frequency range. The composite has shown high shielding effectiveness due to absorption (SEA) of 28.9dB (˜99.9%), which strongly depends on dielectric loss, magnetic permeability, and volume fraction of barium ferrite nanoparticles. The high value of SEA suggests that these composites can be used as a promising radar absorbing materials.

  2. Absorption of folic acid and ascorbic acid from nutrient comparable beverages.

    PubMed

    Carter, Brett; Monsivais, Pablo; Drewnowski, Adam

    2010-01-01

    One hundred percent fruit juices can help consumers increase the nutrient content of the diet since these beverages can be naturally rich in micronutrients. Micronutrient-fortified low-calorie beverages are an important alternative to those wishing to minimize their calorie intakes. However, little is known about the bioavailability of nutrients from fortified beverages relative to 100% fruit juices. The present study examined the bioavailability of ascorbic acid (AA) and folic acid (FA) in 100% orange juice (OJ) and a low-calorie beverage fortified with these nutrients. In a within-subjects, cross-over design, 12 adult men consumed a 591 mL serving of OJ, a low-calorie beverage fortified with AA and FA, and 1% low fat milk. Participants were aged 20 to 35 y, with body mass indexes between 20 and 30 kg/m(2). Blood plasma concentrations of AA and serum concentrations of FA were assayed by serial blood draws, made at 30 min intervals for 4.5 h. Blood plasma concentration of AA was significantly greater after ingestion of the fortified beverage compared to after OJ ingestion. However, the bioavailability of AA did not significantly differ from that of OJ. Analyses of FA indicated no significant difference between fortified beverage and OJ. Consumption of both vitamin containing beverages led to higher concentrations of AA and FA than the milk control. This study showed that similar levels of AA and FA bioavailability can be attained through ingestion of 100% OJ and a fortified beverage.

  3. Asymptotic Solutions for Optical Properties of Large Particles with Strong Absorption

    NASA Technical Reports Server (NTRS)

    Yang, Ping; Gao, Bo-Cai; Baum, Bryan A.; Hu, Yong X.; Wiscombe, Warren J.; Mishchenko, Michael I.; Winker, Dave M.; Nasiri, Shaima L.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    For scattering calculations involving nonspherical particles such as ice crystals, we show that the transverse wave condition is not applicable to the refracted electromagnetic wave in the context of geometric optics when absorption is involved. Either the TM wave condition (i.e., where the magnetic field of the refracted wave is transverse with respect to the wave direction) or the TE wave condition (i.e., where the electric field is transverse with respect to the propagating direction of the wave) may be assumed for the refracted wave in an absorbing medium to locally satisfy the electromagnetic boundary condition in the ray tracing calculation. The wave mode assumed for the refracted wave affects both the reflection and refraction coefficients. As a result, a nonunique solution for these coefficients is derived from the electromagnetic boundary condition. In this study we have identified the appropriate solution for the Fresnel reflection/refraction coefficients in light scattering calculation based on the ray tracing technique. We present the 3 x 2 refraction or transmission matrix that completely accounts for the inhomogeneity of the refracted wave in an absorbing medium. Using the Fresnel coefficients for an absorbing medium, we derive an asymptotic solution in an analytical format for the scattering properties of a general polyhedral particle. Numerical results are presented for hexagonal plates and columns with both preferred and random orientations. The asymptotic theory can produce reasonable accuracy in the phase function calculations in the infrared window region (wavelengths near 10 micron) if the particle size (in diameter) is on the order of 40 micron or larger. However, since strong absorption is assumed in the computation of the single-scattering albedo in the asymptotic theory, the single scattering albedo does not change with variation of the particle size. As a result, the asymptotic theory can lead to substantial errors in the computation of

  4. Microwave absorption properties of double-layer composites using CoZn/NiZn/MnZn-ferrite and titanium dioxide

    NASA Astrophysics Data System (ADS)

    Das, Sukanta; Nayak, G. C.; Sahu, S. K.; Routray, P. C.; Roy, A. K.; Baskey, H.

    2015-03-01

    Zinc substituted ferrite powders Me0.5Zn0.5Fe2O4 (Me=Co, Mn and Ni) were prepared by the sol-gel auto-combustion method. The present study highlights development of Single layer and double layer composite microwave absorbing materials using Ferrites, Titanium dioxide and Epoxy matrix. Moreover microwave absorption property, i.e. reflection loss evaluated at X-band frequency. XRD analysis of the filler particles were carried out to evaluate crystal structure, average crystallite diameter. Morphology of the filler particles were studied with FESEM. Hysteresis behavior of the ferrites samples were studied with Vibrating Sample Magnetometer. The most important parameter governing the absorption properties of microwave absorbers i.e. permittivity and permeability studied in a vector network analyzer. Measured reflection loss value of single-layer NiZn-ferrite based microwave absorber reaches -11.2 dB at 12.05 GHz. Whereas, reflection loss value of double-layer CoZn-ferrite/ TiO2 based microwave absorber reaches -24.3 dB at 12.02 GHz. The result shows that microwave absorption property and bandwidth of absorption of double-layer microwave absorber was found to improve comparison to single layer.

  5. Comparative study of pretreatment methods for the determination of metals in atmospheric aerosol by electrothermal atomic absorption spectrometry.

    PubMed

    Karanasiou, A A; Thomaidis, N S; Eleftheriadis, K; Siskos, P A

    2005-03-15

    A comparative study of pretreatment methods for the determination of 10 elements (As, Cd, Pb, V, Ni, Mn, Cr, Cu, Fe, Al) in atmospheric aerosols by electrothermal atomic absorption spectrometry (ETAAS) was conducted. For the digestion of the particulates collected in filters, six methods were compared using a mixture of HNO(3) and HF with or without the addition of various oxidative agents (HClO(4) or H(2)O(2)) or acids (HCl). The comparative study was performed using loaded cellulose filter samples, which were digested in Parr bombs and heated in a conventional oven at 170 degrees C for 5h. The extraction efficiency and blanks were compared and it was proved that the digestion method using only HNO(3)-HF extracted most of the metals and gave the lowest blanks. The HNO(3)-HF mixture was selected for the development of an improved microwave digestion method specific for aerosol-loaded filters. The operating parameters were optimized, so that quantitative recovery of the reference materials NIST 1649a urban dust and NIST 1648 urban particulate matter was achieved. The blank of cellulose and teflon filters were also determined and compared. Teflon filters present the lowest blanks for all the elements. The obtained limits of detection for each type of filters were adequate for environmental monitoring purposes. ETAAS instrumental operation was also optimized for the compensation and the elimination of interferences. The temperature optimization was performed for each metal in every type of filter and optimized parameters are proposed for 10 elements.

  6. Comparative analysis of the vibrational structure of the absorption spectra of acrolein in the excited ( S 1) electronic state

    NASA Astrophysics Data System (ADS)

    Koroleva, L. A.; Tyulin, V. I.; Matveev, V. K.; Pentin, Yu. A.

    2012-04-01

    The assignments of absorption bands of the vibrational structure of the UV spectrum are compared with the assignments of bands obtained by the CRDS method in a supersonic jet from the time of laser radiation damping for the trans isomer of acrolein in the excited ( S 1) electronic state. The ν00 trans = 25861 cm-1 values and fundamental frequencies, including torsional vibration frequency, obtained by the two methods were found to coincide in the excited electronic state ( S 1) for this isomer. The assignments of several absorption bands of the vibrational structure of the spectrum obtained by the CRDS method were changed. Changes in the assignment of (0-v') transition bands of the torsional vibration of the trans isomer in the Deslandres table from the ν00 trans trans origin allowed the table to be extended to high quantum numbers v'. The torsional vibration frequencies up to v' = 5 were found to be close to the frequencies found by analyzing the vibrational structure of the UV spectrum and calculated quantum-mechanically. The coincidence of the barrier to internal rotation (the cis-trans transition) in the one-dimensional model with that calculated quantum-mechanically using the two-dimensional model corresponds to a planar structure of the acrolein molecule in the excited ( S 1) electronic state.

  7. [Light Absorption Properties of Water-Soluble Organic Carbon (WSOC ) Associated with Particles in Autumn and Winter in the Urban Area of Guangzhou].

    PubMed

    Huang, Huan; Bi, Xin-hui; Peng, Long; Wang, Xin-ming; Sheng, Guo-ying; Fu, Jia-mo

    2016-01-15

    Light absorption properties of water-soluble organic carbon (WSOC) were investigated in the urban area of Guangzhou. The fine particulate matter (PM₂.₅) and size-segregated samples were collected in September and December of 2014 and January of 2015. The variation of absorption with wavelength of WSOC was characterized by the absorption Angström exponent (AAEabs). The AAE values of WSOC in PM₂.₅ were 3.72 ± 0.41 in autumn and 3.91 ± 0.70 in winter, which were lower than those in Beijing and north America. The mass absorption efficiency (MAE) of WSOC at 365 nm wavelength was 0.52 m² · g⁻¹ in autumn and 0.92 m² · g⁻¹ in winter, exhibiting distinct variations between autumn and winter. In winter, the MAEwsoc values exhibited a decreasing trend with increasing particle size, and all size-segregated MAE(WSOC) values in autumn were lower than those in winter, particularly for the particles < 0.95 µm, suggesting more contribution of the secondary formation to WSOC. Comparing the MAE values of elemental carbon (EC) and WSOC, it could be found that the contribution of WSOC to the light extinction of particles couldn't be ignored when the particles were mainly emitted from primary sources.

  8. [Light Absorption Properties of Water-Soluble Organic Carbon (WSOC ) Associated with Particles in Autumn and Winter in the Urban Area of Guangzhou].

    PubMed

    Huang, Huan; Bi, Xin-hui; Peng, Long; Wang, Xin-ming; Sheng, Guo-ying; Fu, Jia-mo

    2016-01-15

    Light absorption properties of water-soluble organic carbon (WSOC) were investigated in the urban area of Guangzhou. The fine particulate matter (PM₂.₅) and size-segregated samples were collected in September and December of 2014 and January of 2015. The variation of absorption with wavelength of WSOC was characterized by the absorption Angström exponent (AAEabs). The AAE values of WSOC in PM₂.₅ were 3.72 ± 0.41 in autumn and 3.91 ± 0.70 in winter, which were lower than those in Beijing and north America. The mass absorption efficiency (MAE) of WSOC at 365 nm wavelength was 0.52 m² · g⁻¹ in autumn and 0.92 m² · g⁻¹ in winter, exhibiting distinct variations between autumn and winter. In winter, the MAEwsoc values exhibited a decreasing trend with increasing particle size, and all size-segregated MAE(WSOC) values in autumn were lower than those in winter, particularly for the particles < 0.95 µm, suggesting more contribution of the secondary formation to WSOC. Comparing the MAE values of elemental carbon (EC) and WSOC, it could be found that the contribution of WSOC to the light extinction of particles couldn't be ignored when the particles were mainly emitted from primary sources. PMID:27078935

  9. Investigation of two-photon absorption properties in new A-D-A compounds emitting blue and yellow fluorescence

    NASA Astrophysics Data System (ADS)

    Jin, Fan; Cai, Zhi-Bin; Huang, Jiu-Qiang; Li, Sheng-Li; Tian, Yu-Peng

    2015-08-01

    Three new acceptor-donor-acceptor compounds (LBQ, DBQ, BYQ) were synthesized and characterized by infrared, hydrogen nuclear magnetic resonance, mass spectrometry and elemental analysis. Their photophysical properties were investigated including linear absorption, single-photon excited fluorescence, fluorescence quantum yield and two-photon absorption. These compounds in CH2Cl2 exhibit good fluorescence quantum yield which are 0.36, 0.26, and 0.25 and the largest two-photon absorption cross-section which are 48, 36, and 181 GM respectively. Under the excitation of Ti: sapphire laser with a pulse width of 140 fs, LBQ and DBQ emit blue two-photon excited fluorescence (TPEF), while BYQ emits bright yellow TPEF. BYQ has a good solubility in water and the σ can be as large as 130 GM, so it shows promising applications in many pharmaceutical and biological fields.

  10. Low frequency absorption properties of a thin metamaterial absorber with cross-array on the surface of a magnetic substrate

    NASA Astrophysics Data System (ADS)

    Chen, Qian; Bie, Shaowei; Yuan, Wei; Xu, Yongshun; Xu, Haibing; Jiang, Jianjun

    2016-10-01

    The design, fabrication, and measurement of a metamaterial with broadband microwave absorption properties in the low frequency range are presented in this paper. The metamaterial has a layered structure with a thickness of 2.2 mm, and consists of a conventional printed circuit board (PCB) process fabricated cross array on the surface of a flake-shaped carbonyl iron (CI) powder-filled silicon rubber composite magnetic substrate backed by a metal plane. The measurement results indicate that the absorption bandwidth (defined as the frequency range with reflection coefficient below  -10 dB) of the proposed structure is 2.55 GHz-5.68 GHz. The power loss mechanism was outlined according to the current distribution on and off the resonance frequency. Moreover, the absorption performance of the proposed structure for incident angles ranging from 0° to 60° for both transverse electric (TE) wave and transverse magnetic (TM) waves were exhibited.

  11. Metal-free phthalocyanine aggregation and binding with amines: Specific and general solvent effects on absorption and fluorescence properties

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Zhang, Xian-Fu; Lu, Xulin

    2015-03-01

    The fluorescence and absorption properties of a metal-free phthalocyanine (Pc) H2PcR4 and its zinc-centered complex ZnPcR4 (R is the isopropyloxy at the β-position of a Pc ring) were measured and compared in protic and aprotic solvents. H2PcR4 shows strong bonding interaction with amines and aggregation in alcohols in addition to the general solvent effect in aprotic solvents due to polarity change. The specific solvent effect leads to substantial changes in its spectra, fluorescence quantum yield (Φf) and fluorescence lifetime (τf) values. In contrast, ZnPcR4 does not show the specific effects due to the presence of a central element in a Pc cavity. For H2PcR4 the change of solvents caused a large variation of Φf (0.050-0.48) and τf (3.45-6.88 ns), in contrast to the slight changes for ZnPcR4. On the other hand, the general solvent effect of H2PcR4 due to polarity is also more significant than that of ZnPcR4. The increase of solvent polarity decreases both Φf and τf, but increases the Stoke's shift.

  12. Dicyanobenzene and dicyanopyrazine derived X-shaped charge-transfer chromophores: comparative and structure-property relationship study.

    PubMed

    Dokládalová, L; Bureš, F; Kuznik, W; Kityk, I V; Wojciechowski, A; Mikysek, T; Almonasy, N; Ramaiyan, M; Padělková, Z; Kulhánek, J; Ludwig, M

    2014-08-01

    A series of novel X-shaped push-pull compounds based on benzene-1,2-dicarbonitrile has been designed, synthesized and further investigated by X-ray analysis, electrochemistry, absorption and emission spectra, SHG experiment and quantum-chemical calculations. The obtained data were compared with those for isolobal 5,6-disubstituted pyrazine-2,3-dicarbonitriles. Structure-property relationships were elucidated. The extension, composition and planarization of the π-linker used as well as the electron-withdrawing ability of both dicyano-substituted acceptor units affect the linear and nonlinear properties of the target charge-transfer chromophores most significantly.

  13. Effect of acetylation and succinylation on solubility profile, water absorption capacity, oil absorption capacity and emulsifying properties of mucuna bean (Mucuna pruriens) protein concentrate.

    PubMed

    Lawal, O S; Adebowale, K O

    2004-04-01

    Mucuna protein concentrate was acylated with succinic and acetic anhydride. The effects of acylation on solubility, water absorption capacity, oil absorption capacity and emulsifying properties were investigated. The pH-dependent solubility profile of unmodified mucuna protein concentrate (U-mpc) showed a decrease in solubility with decrease in pH and resolubilisation at pH values acidic to isoelectric pH (pH 4). Apart from pH 2, both acetylated mucuna protein concentrates (A-mpc) and succinylated mucuna protein concentrate (S-mpc) had improved solubility over the unmodified derivative. Acylation increased the water absorption capacity (WAC) at all levels of ionic strength (0.1-1.0 M). WAC of the protein samples increased with increase in ionic strength up to 0.2 M after which a decline occurred with increase in ionic strength from 0.4-1.0 M. When protein solutions were prepared in salts of various ions, increase in WAC followed the Hofmeister series in the order: NaSCN < NaClO4 < NaI < NaBr < NaCl < Na2SO. Acetylation improved the oil absorption capacity while the lipophilic tendency reduced the following succinylation. Emulsifying capacity increased with increase in concentration up to 2, 4 and 5% w/v for U-mpc, A-mpc and S-mpc, respectively, after which an increase in concentration reduced the emulsifying capacity. Both acetylation and succinylation significantly (P < 0.05) improved the emulsifying capacity at pH 4-10. Initial increase in ionic strength up to 0.4 M for U-mpc and 0.4 M for A-mpc and S-mpc increased the emulsion capacity progressively. Further increase in ionic strength reduced emulsion capacity (EC). Contrary to the effect of various salts on WAC, increase in EC generally follows the series Na2SO4 < NaCl < NaBr < NaI < NaClO4 < NaSCN. At all levels of ionic strength studied, S-mpc had a better emulsifying activity (EA) than both A-mpc and U-mpc. EA and emulsifying stability (ES) were pH-dependent. Maximum EA and ES were recorded at pH 10. ES of

  14. Absorption properties of alternative chromophores for use in laser tissue soldering applications.

    PubMed

    Byrd, Brian D; Heintzelman, Douglas L; McNally-Heintzelman, Karen M

    2003-01-01

    The feasibility of using alternative chromophores in laser tissue soldering applications was explored. Two commonly used chromophores, indocyanine green (ICG), and methylene blue (MB) were investigated, as well as three different food colorings: red #40 (RFC), blue #1 (BFC), and green consisting of yellow #5 and blue #1 (GFC). Three experimental studies were conducted: (i) The absorption profiles of the five chromophores, when diluted in deionized water and when bound to protein, were recorded; (ii) the effect of accumulated thermal dosages on the absorption profile of the chromophores was evaluated; and (iii) the stability of the absorption profiles of the chromophore-doped solutions when exposed to ambient light for extended time periods was measured. The peak absorption wavelengths of ICG, MB, RFC, and BFC, were found to be 805 nm, 665 nm, 503 nm, and 630 nm respectively in protein solder. The GFC had two absorption peaks at 426 nm and 630 nm, corresponding to the two dye components comprising this color. The peak absorption wavelength of ICG and MB was dependent on the choice of solvent (deionized water or protein). In contrast, the peak absorption wavelengths of the three chromophores were not dependent on the choice of solvent. ICG and MB showed a significant decrease in absorbance units with increased time and temperature when heated to temperature up to 100 degrees C. A significant decrease in the absorption peak occurred in the ICG and MB samples when exposed to ambient light for a period of 7 days. Negligible change in absorption with accumulated thermal dose up to 100 degrees C or light dose (over a period of 84 days) was observed for any of the three food colorings investigated. PMID:12724860

  15. Absorption properties of alternative chromophores for use in laser tissue soldering applications.

    PubMed

    Byrd, Brian D; Heintzelman, Douglas L; McNally-Heintzelman, Karen M

    2003-01-01

    The feasibility of using alternative chromophores in laser tissue soldering applications was explored. Two commonly used chromophores, indocyanine green (ICG), and methylene blue (MB) were investigated, as well as three different food colorings: red #40 (RFC), blue #1 (BFC), and green consisting of yellow #5 and blue #1 (GFC). Three experimental studies were conducted: (i) The absorption profiles of the five chromophores, when diluted in deionized water and when bound to protein, were recorded; (ii) the effect of accumulated thermal dosages on the absorption profile of the chromophores was evaluated; and (iii) the stability of the absorption profiles of the chromophore-doped solutions when exposed to ambient light for extended time periods was measured. The peak absorption wavelengths of ICG, MB, RFC, and BFC, were found to be 805 nm, 665 nm, 503 nm, and 630 nm respectively in protein solder. The GFC had two absorption peaks at 426 nm and 630 nm, corresponding to the two dye components comprising this color. The peak absorption wavelength of ICG and MB was dependent on the choice of solvent (deionized water or protein). In contrast, the peak absorption wavelengths of the three chromophores were not dependent on the choice of solvent. ICG and MB showed a significant decrease in absorbance units with increased time and temperature when heated to temperature up to 100 degrees C. A significant decrease in the absorption peak occurred in the ICG and MB samples when exposed to ambient light for a period of 7 days. Negligible change in absorption with accumulated thermal dose up to 100 degrees C or light dose (over a period of 84 days) was observed for any of the three food colorings investigated.

  16. Enhanced Dielectric Properties and High-Temperature Microwave Absorption Performance of Zn-Doped Al2O3 Ceramic

    NASA Astrophysics Data System (ADS)

    Wang, Yuan; Luo, Fa; Wei, Ping; Zhou, Wancheng; Zhu, Dongmei

    2015-07-01

    To improve the dielectric and microwave absorption properties of Al2O3 ceramic, Zn-doped Al2O3 ceramic was prepared by conventional ceramic processing. X-ray diffraction analysis confirmed that Zn atoms successfully entered the Al2O3 ceramic lattice and occupied Al sites. The complex permittivity increased with increasing Zn concentration, which is mainly attributed to the increase in charged vacancy defects and densification of the Al2O3 ceramic. In addition, the temperature-dependent complex permittivity of 3% Zn-doped Al2O3 ceramic was determined in the temperature range from 298 K to 873 K. Both the real and imaginary parts of the complex permittivity increased monotonically with increasing temperature, which can be ascribed to the shortened relaxation time and increasing electrical conductivity. The increased complex permittivity leads to a great improvement in microwave absorption. In particular, when the temperature is up to 873 K, the 3% Zn-doped Al2O3 ceramic exhibited the best absorption performance with a maximum peak (-12.1 dB) and broad effective absorption bandwidth (reflection loss less than -10 dB from 9.3 GHz to 12.3 GHz). These results reveal that Zn-doped Al2O3 ceramic is a promising candidate for use as a kind of high-temperature microwave absorption material.

  17. Study of nonlinear optical absorption properties of V2O5 nanoparticles in the femtosecond excitation regime

    NASA Astrophysics Data System (ADS)

    Molli, Muralikrishna; Bhat Kademane, Abhijit; Pradhan, Prabin; Sai Muthukumar, V.

    2016-08-01

    In this work, we report for the first time, the nonlinear optical absorption properties of vanadium pentoxide (V2O5) nanoparticles in the femtosecond excitation regime. V2O5 nanoparticles were synthesized through solution combustion technique. The as-synthesized samples were further characterized using XRD, FESEM, EDAX, TEM and UV-visible spectroscopy. X-ray diffraction results revealed the crystalline nature of the nanoparticles. Electron microscopy studies showed the size of the nanoparticles to be ~200 nm. Open-aperture z-scan technique was employed to study the nonlinear optical absorption behavior of the synthesized samples using a 100-fs laser pulses at 800 nm from a regeneratively amplified Ti: sapphire laser. The mechanism of nonlinear absorption was found to be a three-photon absorption process which was explained using the density of states of V2O5 obtained using density functional theory. These nanoparticles exhibit strong intensity-dependent nonlinear optical absorption and hence could be considered for optical-power-limiting applications.

  18. Light absorption and morphological properties of soot-containing aerosols observed at an East Asian outflow site, Noto Peninsula, Japan

    NASA Astrophysics Data System (ADS)

    Ueda, S.; Nakayama, T.; Taketani, F.; Adachi, K.; Matsuki, A.; Iwamoto, Y.; Sadanaga, Y.; Matsumi, Y.

    2015-09-01

    The coating of black carbon (BC) with inorganic salts and organic compounds can enhance the magnitude of light absorption by BC. To elucidate the enhancement of light absorption of aged BC particles and its relation to the mixing state and morphology of individual particles, we conducted observations of particles at an Asian outflow site in Noto Peninsula, Japan, in the spring of 2013. Absorption and scattering coefficients at 405, 532, and 781 nm and mass concentrations/mixing states of refractory-BC in PM2.5 were measured using a three-wavelength photoacoustic soot spectrometer and a single-particle soot photometer (SP2), respectively, after passage through a heater maintained at 300 or 400 °C or a bypass line maintained at room temperature (25 °C). The average enhancement of BC light absorption due to coating was estimated by comparing absorption coefficients at 781 nm for particles that with and without passing through the heater and was found to be 22-23 %. The largest enhancements (> 30 %) were observed under high absorption coefficient conditions when the air mass was long-range transported from urban areas in China. Aerosol samples were also analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. The morphological features and mixing states of soot-containing particles of four samples collected during the high absorption coefficient events were analyzed by comparing microphotographs before and after the evaporation of beam-sensitive materials by irradiation with a high density electron beam. The majority of the soot in all samples was found as mixed particles with spherical sulfate or as clusters of sulfate spherules. For samples showing high enhancement (> 30 %) of BC light absorption, TEM showed that the internally mixed soot-containing particles tended to have a more spherical shape and to be embedded into the sulfate. The SP2 measurements also suggested that the proportion of thickly-coated soot was

  19. Light absorption and morphological properties of soot-containing aerosols observed at an East Asian outflow site, Noto Peninsula, Japan

    NASA Astrophysics Data System (ADS)

    Ueda, Sayako; Nakayama, Tomoki; Taketani, Fumikazu; Adachi, Kouji; Matsuki, Atsushi; Iwamoto, Yoko; Sadanaga, Yasuhiro; Matsumi, Yutaka

    2016-03-01

    The coating of black carbon (BC) with inorganic salts and organic compounds can enhance the magnitude of light absorption by BC. To elucidate the enhancement of light absorption of aged BC particles and its relation to the mixing state and morphology of individual particles, we conducted observations of particles at an Asian outflow site in Noto Peninsula, Japan, in the spring of 2013. Absorption and scattering coefficients at 405, 532, and 781 nm and mass concentrations/mixing states of refractory BC in PM2.5 were measured using a three-wavelength photoacoustic soot spectrometer and a single-particle soot photometer (SP2), respectively, after passage through a thermodenuder (TD) maintained at 300 or 400 °C or a bypass line maintained at room temperature (25 °C). The average enhancement factor of BC light absorption due to coating was estimated by comparing absorption coefficients at 781 nm for particles that with and without passing through the TD at 300 °C and was found to be 1.22. The largest enhancements (> 1.30) were observed under high absorption coefficient periods when the air mass was long-range transported from urban areas in China. Aerosol samples were also analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. The morphological features and mixing states of soot-containing particles of four samples collected during the high absorption events were analyzed by comparing microphotographs before and after the evaporation of beam-sensitive materials by irradiation with a high-density electron beam. The majority of the soot in all samples was found as mixed particles with sulfate-containing spherules or as clusters of such spherules. For samples showing high enhancement (> 1.30) of BC light absorption, the TEM showed that the internally mixed soot-containing particles tended to have a more spherical shape and to be thickly coated. The SP2 measurements also suggested that the proportion of thickly coated

  20. Comparative study of the immunobiological properties of live brucellosis vaccines.

    PubMed

    Salmakov, K M; Fomin, A M; Plotnikova, E M; Safina, G M; Galimova, G M; Salmakova, A V; Ivanov, A V; Panin, A N; Sklyarov, O D; Shumilov, K V; Klimanov, A I

    2010-10-01

    Findings from the comparative study of the immunobiological properties of live brucellosis vaccines in guinea pigs are presented in the article. Vaccines from strains Brucella abortus 19 (U.S.) and 82 (Russia), in the S and SR forms, respectively, exhibited the highest and most pronounced immunological efficacy, while vaccines from strains B. abortus 82-PS (in the RS form) and B. abortus RB-51 and 75/79-AB (in the R forms) exhibited the lowest. The live vaccine from strain B. abortus 82, together with a high immunological activity, possesses inagglutinogenic properties. The great advantage of this vaccine over the vaccine from strain B. abortus 19 is that after its use in animals the problem of the differential diagnosis of brucellosis becomes much simpler. The live vaccine from strain B. abortus 82 was adopted in veterinary practice in the Russian Federation; it is widely used for the targeted prevention of bovine brucellosis, but can also be used successfully for wild animals such as bison, deer, elk, and others.

  1. Nanoparticles and 3D sponge-like porous networks of manganese oxides and their microwave absorption properties.

    PubMed

    Yan, D; Cheng, S; Zhuo, R F; Chen, J T; Feng, J J; Feng, H T; Li, H J; Wu, Z G; Wang, J; Yan, P X

    2009-03-11

    Hydrohausmannite nanoparticles (approximately 10 nm) were prepared by the hydrothermal method at 100 degrees C for 72 h. Subsequent annealing was done in air at 400 degrees C and 800 degrees C for 10 h, Mn(3)O(4) nanoparticles (approximately 25 nm) and 3D Mn(2)O(3) porous networks were obtained, respectively. The products were characterized by XRD, TEM, SAED and FESEM. Time-dependent experiments were carried out to exhibit the formation process of the Mn(2)O(3) networks. Their microwave absorption properties were investigated by mixing the product and paraffin wax with 50 vol%. The Mn(3)O(4) nanoparticles possess excellent microwave absorbing properties with the minimum reflection loss of -27.1 dB at 3.1 GHz. In contrast, the Mn(2)O(3) networks show the weakest absorption of all samples. The absorption becomes weaker with the annealing time increasing at 800 degrees C. The attenuation of microwave can be attributed to dielectric loss and their absorption mechanism was discussed in detail. PMID:19417534

  2. The Dust, Nebular Emission, and Dependence on QSO Radio Properties of the Associated Mg II Absorption Line Systems

    NASA Astrophysics Data System (ADS)

    Khare, Pushpa; Berk Daniel, Vanden; Rahmani, Hadi; York, Donald G.

    2014-10-01

    We studied dust reddening and [O II] emission in 1730 Mg II associated absorption systems (AAS; relative velocity with respect to QSOs, <=3000 km s-1 in units of velocity of light, β, <=0.01) with 0.4 <=z abs <= 2 in the Sloan Digital Sky Survey DR7, focusing on their dependence on the radio and other QSO properties. We used control samples, several with matching radio properties, to show that (1) AAS in radio-detected (RD) QSOs cause 2.6 ± 0.2 times higher dust extinction than those in radio-undetected (RUD) ones, which in turn cause 2.9 ± 0.7 times the dust extinction in the intervening systems; (2) AAS in core-dominated QSOs cause 2.0 ± 0.1 times higher dust extinction than those in lobe-dominated QSOs; (3) the occurrence of AAS is 2.1 ± 0.2 times more likely in RD QSOs than in RUD QSOs and 1.8 ± 0.1 time more likely in QSOs having black holes with masses larger than 1.23 × 109 M ⊙ than in those with lower-mass black holes; and (4) there is excess flux in [O II]λ3727 emission in the composite spectra of the AAS samples compared with those of the control samples, which is at the emission redshift. The presence of AAS enhances the O II emission from the active galactic nucleus and/or the host galaxy. This excess is similar for both RD and RUD samples and is 2.5 ± 0.4 times higher in lobe-dominated samples than in core-dominated samples. The excess depends on the black hole mass and Eddington ratio. All these point to the intrinsic nature of the AAS except for the systems with z abs > z em, which could be infalling galaxies.

  3. Properties of Liquid Silicon Observed by Time-Resolved X-Ray Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Johnson, S. L.; Heimann, P. A.; Lindenberg, A. M.; Jeschke, H. O.; Garcia, M. E.; Chang, Z.; Lee, R. W.; Rehr, J. J.; Falcone, R. W.

    2003-10-01

    Time-resolved x-ray spectroscopy at the Si L edges is used to probe the electronic structure of an amorphous Si foil as it melts following absorption of an ultrafast laser pulse. Picosecond temporal resolution allows observation of the transient liquid phase before vaporization and before the liquid breaks up into droplets. The melting causes changes in the spectrum that match predictions of molecular dynamics and ab initio x-ray absorption codes.

  4. Link between K absorption edges and thermodynamic properties of warm dense plasmas established by an improved first-principles method

    NASA Astrophysics Data System (ADS)

    Zhang, Shen; Zhao, Shijun; Kang, Wei; Zhang, Ping; He, Xian-Tu

    2016-03-01

    A precise calculation that translates shifts of x-ray K absorption edges to variations of thermodynamic properties allows quantitative characterization of interior thermodynamic properties of warm dense plasmas by x-ray absorption techniques, which provides essential information for inertial confinement fusion and other astrophysical applications. We show that this interpretation can be achieved through an improved first-principles method. Our calculation shows that the shift of K edges exhibits selective sensitivity to thermal parameters and thus would be a suitable temperature index to warm dense plasmas. We also show with a simple model that the shift of K edges can be used to detect inhomogeneity inside warm dense plasmas when combined with other experimental tools.

  5. Influence of Ni/Co molar ratio on electromagnetic properties and microwave absorption performances for Ni/Co paraffin composites

    NASA Astrophysics Data System (ADS)

    Yan, S. J.; Dai, S. L.; Ding, H. Y.; Wang, Z. Y.; Liu, D. B.

    2014-05-01

    Ni and Co metallic microparticles with submicron size were synthesized with a simple wet chemical reduction method at a relatively low temperature. Then their morphologies and structures were characterized by SEM and XRD. Ni metallic microparticles have spherical-shape morphology with fcc crystalline structure, however, Co has a distinct leaf-like morphology with the fcc and hcp mixed phases crystalline structures. For the characterization of their electromagnetic properties, paraffin matrix composites containing different molar ratio Ni and Co mixture powder as fillers were prepared. It was found that both the electromagnetic properties and electromagnetic microwave absorption performances of absorber layer were remarkably influenced by Ni/Co molar ratio. The electromagnetic microwave absorption performances were significantly improved by blending Ni and Co metallic microparticles into paraffin matrix with changing Ni/Co molar ratio, and enhanced mechanism were discussed.

  6. Enhanced microwave absorption properties in BiFeO 3 ceramics prepared by high-pressure synthesis

    NASA Astrophysics Data System (ADS)

    Wen, Fusheng; Wang, Nan; Zhang, Fang

    2010-10-01

    Multiferroic BiFeO 3 nanoparticles and ceramics have been successfully prepared by sol-gel method and following high-pressure synthesis. The denser samples, good crystallization and crystal structure deformation have been obtained via high-pressure synthesis proved by XRD, SEM and Raman spectra. The enhanced magnetization of high-pressure samples attributes to crystal structure deformation; moreover, the enhanced dielectric loss of high-pressure samples results from good crystallization. The better microwave absorption properties can be obtained by high-pressure synthesis, and the minimum reflection loss elevates from -13 dB at 12.4 GHz to -17 dB at 11.2 GHz. It means that the high-pressure synthesis can effectively improve microwave absorption properties of multiferroic materials.

  7. Microwave Absorption Properties of Ni-Foped SiC Powders in the 2-18 GHz Frequency Range

    NASA Astrophysics Data System (ADS)

    Jin, Hai-Bo; Li, Dan; Cao, Mao-Sheng; Dou, Yan-Kun; Chen, Tao; Wen, Bo; Simeon, Agathopoulos

    2011-03-01

    Ni-doped SiC powder with improved dielectric and microwave absorption properties was prepared by self-propagating high-temperature synthesis (SHS). The XRD analysis of the as-synthesized powders suggests that Ni is accommodated in the sites of Si in the lattice of SiC, which shrinks in the presence of Ni. The experimental results show an improvement in the dielectric properties of the Ni-doped SiC powder in the frequency range of 2-18 GHz. The bandwidth of the reflection loss below -10 dB is broadened from 3.04 (for pure SiC) to 4.56 GHz (for Ni-doped SiC), as well as the maximum reflection loss of produced powders from 13.34 to 22.57 dB, indicating that Ni-doped SiC could be used as an effective microwave absorption material.

  8. Pork meat increases iron absorption from a 5-day fully controlled diet when compared to a vegetarian diet with similar vitamin C and phytic acid content.

    PubMed

    Bach Kristensen, Mette; Hels, Ole; Morberg, Catrine; Marving, Jens; Bügel, Susanne; Tetens, Inge

    2005-07-01

    Meat increases absorption of non-haem iron in single-meal studies. The aim of the present study was to investigate, over a 5 d period, the potential increasing effect of consumption of pork meat in a whole diet on the fractional absorption of non-haem iron and the total absorption of iron, when compared to a vegetarian diet. A randomised cross-over design with 3 x 5 d whole-diet periods with diets containing Danish-produced meat, Polish-produced meat or a vegetarian diet was conducted. Nineteen healthy female subjects completed the study. All main meals in the meat diets contained 60 g of pork meat and all diets had high phytic acid content (1250 mumol/d). All main meals were extrinsically labelled with the radioactive isotope (59)Fe and absorption of iron was measured in a whole body counter. The non-haem iron absorption from the Danish meat diet was significantly higher compared to the vegetarian diet (P=0.031). The mean fractional absorption of non-haem iron was 7.9 (se1.1), 6.8 (se 1.0) and 5.3 (se 0.6) % for the Danish and Polish meat diets and vegetarian diet, respectively. Total absorption of iron was higher for both meat diets compared to the vegetarian diet (Danish meat diet: P=0.006, Polish meat diet: P=0.003). The absorption ratios of the present study were well in accordance with absorption ratios estimated using algorithms on iron bioavailability. Neither the meat diets nor the vegetarian diets fulfilled the estimated daily requirements of absorbed iron in spite of a meat intake of 180 g/d in the meat diets.

  9. Synthesis and electromagnetic absorption properties of micro-nano nickel powders prepared with liquid phase reduction method

    NASA Astrophysics Data System (ADS)

    Yu, Ying; Ma, Hua; Tian, Xiao-Xia; Du, Hong-Liang; Xia, Song; Qu, Shao-Bo

    2016-09-01

    Monodisperse micro-nano nickel powders have been prepared by chemical reduction of aqueous solution NiSO4, NaOH and NaH2PO2, and the influence of pH value and initial concentration of NiSO4 on the size, structure, morphology and microwave absorption properties of nickel powders were investigated. The crystal structure of nickel powders was characterized by X-ray diffraction (XRD). And the morphology of the as-synthesized products was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The microwave absorption properties of the composite materials were characterized by network analyzer. The result indicates that the growth of nickel powders produced by NiSO4 and NaH2PO2 at alkaline condition deeply relies on pH value and initial concentration of NiSO4 in reaction system. Different sizes of nickel powders with the diameter of 1.5μm and 180nm were produced at the pH value of 10 and initial concentration of NiSO4 at 0.5mol/L. The network analyzer showed definite microwave absorption properties of nickel powders with different sizes in the range of 0.5-18.0GHz.

  10. Absorption properties of high-latitude Norwegian coastal water: The impact of CDOM and particulate matter

    NASA Astrophysics Data System (ADS)

    Nima, Ciren; Frette, Øyvind; Hamre, Børge; Erga, Svein Rune; Chen, Yi-Chun; Zhao, Lu; Sørensen, Kai; Norli, Marit; Stamnes, Knut; Stamnes, Jakob J.

    2016-09-01

    We present data from measurements and analyses of the spectral absorption due to colored dissolved organic matter (CDOM), total suspended matter (TSM), phytoplankton, and non-algal particles (NAP) in high-latitude northern Norwegian coastal water based on samples taken in spring, summer, and autumn. The Chlorophyll-a (Chl-a) concentration was found to vary significantly with season, whereas regardless of season CDOM was found to be the dominant absorber for wavelengths shorter than 600 nm. The absorption spectral slope S350-500 for CDOM varied between 0.011 and 0.022 nm-1 with mean value and standard deviation given by (0.015 ± 0.002) nm-1. The absorption spectral slope was found to be strongly dependent on the wavelength interval used for fitting. On average, S280-500 was found to be 43% higher than S350-500. A linear relationship was found between the base 10 logarithm of the absorption coefficient at 440 nm [log(ag(440))] and S350-500. Regardless of season, phytoplankton were the dominant component of the TSM absorption indicating little influence from land drainage. The mean values of the Chl-a specific absorption coefficient of phytoplankton aph*(λ) at 440 nm and 676 nm were 0.052 m2 mg-1 and 0.023 m2 mg-1, respectively, and aph*(λ) was found to vary with season, being higher in summer and autumn than in spring. The absorption spectral slope SNAP, which is the spectral slope of absorption spectrum for non-algal particles, was lower than that for European coastal water in general. It varied between 0.0048 and 0.022 nm-1 with mean value and standard deviation given by (0.0083-1 ± 0.003) nm-1. Comparisons of absorption coefficients measured in situ using an ac-9 instrument with those measured in the laboratory from water samples show a good agreement.

  11. Light absorption, optical and microphysical properties of trajectory-clustered aerosols at two AERONET sites in West Africa

    NASA Astrophysics Data System (ADS)

    Fawole, O. G.; Cai, X.; MacKenzie, A. R.

    2015-12-01

    Aerosol remote sensing techniques and back-trajectory modeling can be combined to identify aerosol types. We have clustered 7 years of AERONET aerosol signals using trajectory analysis to identify dominant aerosol sources at two AERONET sites in West Africa: Ilorin (4.34 oE, 8.32 oN) and Djougou (1.60 oE, 9.76 oN). Of particular interest are air masses that have passed through the gas flaring region in the Niger Delta area, of Nigeria, en-route the AERONET sites. 7-day back trajectories were calculated using the UK UGAMP trajectory model driven by ECMWF wind analyses data. Dominant sources identified, using literature classifications, are desert dust (DD), Biomass burning (BB) and Urban-Industrial (UI). Below, we use a combination of synoptic trajectories and aerosol optical properties to distinguish a fourth source: that due to gas flaring. Gas flaring, (GF) the disposal of gas through stack in an open-air flame, is believed to be a prominent source of black carbon (BC) and greenhouse gases. For these different aerosol source signatures, single scattering albedo (SSA), refractive index , extinction Angstrom exponent (EEA) and absorption Angstrom exponent (AAE) were used to classify the light absorption characteristics of the aerosols for λ = 440, 675, 870 and1020 nm. A total of 1625 daily averages of aerosol data were collected for the two sites. Of which 245 make up the GF cluster for both sites. For GF cluster, the range of fine-mode fraction is 0.4 - 0.7. Average values SSA(λ), for the total and GF clusters are 0.90(440), 0.93(675), 0.95(870) and 0.96(1020), and 0.93(440), 0.92(675), 0.9(870) and 0.9(1020), respectively. Values of for the GF clusters for both sites are 0.62 - 1.11, compared to 1.28 - 1.66 for the remainder of the clusters, which strongly indicates the dominance of carbonaceous particles (BC), typical of a highly industrial area. An average value of 1.58 for the real part of the refractive index at low SSA for aerosol in the GF cluster is also

  12. Geometric Structure Determination of N694C Lipoxygenase: a Comparative Near-Edge X-Ray Absorption Spectroscopy And Extended X-Ray Absorption Fine Structure Study

    SciTech Connect

    Sarangi, R.; Hocking, R.K.; Neidig, M.L.; Benfatto, M.; Holman, T.R.; Solomon, E.I.; Hodgson, K.O.; Hedman, B.

    2009-05-27

    The mononuclear nonheme iron active site of N694C soybean lipoxygenase (sLO1) has been investigated in the resting ferrous form using a combination of Fe-K-pre-edge, near-edge (using the minuit X-ray absorption near-edge full multiple-scattering approach), and extended X-ray absorption fine structure (EXAFS) methods. The results indicate that the active site is six-coordinate (6C) with a large perturbation in the first-shell bond distances in comparison to the more ordered octahedral site in wild-type sLO1. Upon mutation of the asparigine to cystiene, the short Fe-O interaction with asparigine is replaced by a weak Fe-(H{sub 2}O), which leads to a distorted 6C site with an effective 5C ligand field. In addition, it is shown that near-edge multiple scattering analysis can give important three-dimensional structural information, which usually cannot be accessed using EXAFS analysis. It is further shown that, relative to EXAFS, near-edge analysis is more sensitive to partial coordination numbers and can be potentially used as a tool for structure determination in a mixture of chemical species.

  13. Magnetic and microwave absorption properties of ZnCo-substituted W-type strontium hexaferrite

    NASA Astrophysics Data System (ADS)

    Farhadizadeh, A. R.; Seyyed Ebrahimi, S. A.; Masoudpanah, S. M.

    2015-05-01

    Single phase ZnCo-substituted W-type strontium hexaferrite (SrZn2-xCoxFe16O27 with x=0-2.0) were prepared by ceramic conventional method. With the Co substitution, the saturation magnetization increases up to a maximum of 72.8 emu/g for SrZnCoFe16O27, and then decreases, while the coercivity decreases from 1000 Oe for x=0 to 430 Oe for x=1 and then increases up to 700 Oe for x=2. The microwave absorption measurements in the microwave frequency range of 8-12 GHz (X-band) exhibited the maximum absorption of -28 dB at 10.3 GHz with an absorption bandwidth of more than 2.1 GHz for x=1.

  14. pH-Induced Modulation of One- and Two-Photon Absorption Properties in a Naphthalene-Based Molecular Probe.

    PubMed

    Murugan, N Arul; Kongsted, Jacob; Ågren, Hans

    2013-08-13

    Presently, there is a great demand for small probe molecules that can be used for two-photon excitation microscopy (TPM)-based monitoring of intracellular and intraorganelle activity and pH. The candidate molecules should ideally possess a large two-photon absorption cross section with optical properties sensitive to pH changes. In the present work, we investigate the potential of a methoxy napthalene (MONAP) derivative for its suitability to serve as a pH sensor using TPM. Using an integrated approach rooted in hybrid quantum mechanics/molecular mechanics, the structures, dynamics, and the one- and two-photon properties of the probe in dimethylformamide solvent are studied. It is found that the protonated form is responsible for the optical property of MONAP at moderately low pH, for which the calculated pH-induced red shift is in good agreement with experiments. A 2-fold increase in the two-photon absorption cross section in the IR region of the spectrum is predicted for the moderately low pH form of the probe, suggesting that this can be a potential probe for pH monitoring of living cells. We also propose some design principles aimed at obtaining control of the absorption spectral range of the probe by structural tuning. Our work indicates that the integrated approach employed is capable of capturing the pH-induced changes in structure and optical properties of organic molecular probes and that such in silico tools can be used to draw structure-property relationships to design novel molecular probes suitable for a specific application.

  15. Study of nonlinear optical absorption properties of Sb2Se3 nanoparticles in the nanosecond and femtosecond excitation regime

    NASA Astrophysics Data System (ADS)

    Molli, Muralikrishna; Pradhan, Prabin; Dutta, Devarun; Jayaraman, Aditya; Bhat Kademane, Abhijit; Muthukumar, V. Sai; Kamisetti, Venkataramaniah; Philip, Reji

    2016-05-01

    In this work, we report for the first time, the nonlinear optical absorption properties of antimony selenide (Sb2Se3) nanoparticles synthesized through solvothermal route. X-ray diffraction results revealed the crystalline nature of the nanoparticles. Electron microscopy studies revealed that the nanoparticles are in the range of 10-40 nm. Elemental analysis was performed using EDAX. The nanosecond optical limiting effect was characterized by using fluence-dependent transmittance measurements with 15-ns laser pulses at 532 and 1064 nm excitation wavelengths. Mechanistically, effective two-photon (2PA) absorption and nonlinear scattering processes were the dominant nonlinear processes at both the wavelengths. At 800 nm excitation in the femtosecond regime (100 fs), the nonlinear optical absorption was found to be a three-photon (3PA) process. Both 2PA and 3PA processes were explained using the band structure and density of states of Sb2Se3 obtained using density functional theory. These nanoparticles exhibit strong intensity-dependent nonlinear optical absorption and hence could be considered to have optical power-limiting applications in the visible range.

  16. Third-order nonlinear optical properties of colloidal Au nanorods systems: saturable and reverse-saturable absorption.

    PubMed

    García-Ramírez, E V; Almaguer-Valenzuela, S; Sánchez-Dena, O; Baldovino-Pantaleón, O; Reyes-Esqueda, J A

    2016-01-25

    In this work, we present a study of the nonlinear absorption properties from different gold nanorod (NR) systems in aqueous suspension. The NRs were obtained with the bottom-up protocol by the seed-mediated growth method (SMG), using Ag(+) ions at different concentrations, and CTAB as surfactant. By using this method, aspect ratios between 2 and 5 were obtained. The transverse surface plasmons (TSP) are located between 514 - 535 nm, while the longitudinal surface plasmons (LSP) are between 639 - 921 nm, for the different samples studied. The Z-scan technique was implemented for open (OA) and closed (CA) aperture at 532 and 1064 nm, with laser pulses of 26 ps, for vertical and horizontal polarizations, with respect to the incidence plane (horizontal). At 532 nm all samples showed saturable absorption (SA), while for samples with LSP near 1064 nm, such effect was observed only at low-energy pulse experimental conditions. In the high-energy pulse regime, an apparent reverse-saturable absorption (RSA) was observed for both wavelengths. However for 532 nm, it was possible to determine that this effect results from structural changes in the samples, which are manifested through the behavior of nonlinear absorption and refraction curves. These results were used to determine the irradiances to which NRs can be modified by photodegradation. PMID:26832569

  17. Absorption and scattering properties of the Martian dust in the solar wavelengths

    NASA Technical Reports Server (NTRS)

    Ockert-Bell, M. E.; Pollack, J. B.; McKay, C. P.; Forget, F.

    1997-01-01

    A new wavelength-dependent model of the single-scattering properties of the Martian dust is presented. The model encompasses the solar wavelengths (0.3 to 4.3 micrometers at 0.02 micrometer resolution) and does not assume a particular mineralogical composition of the particles. We use the particle size distribution, shape, and single-scattering properties at Viking Lander wavelengths presented by Pollack et al. [1995]. We expand the wavelength range of the aerosol model by assuming that the atmospheric dust complex index of refraction is the same as that of dust particles in the bright surface geologic units. The new wavelength-dependent model is compared to observations taken by the Viking Orbiter Infrared Thermal Mapper solar channel instrument during two dust storms. The model accurately matches afternoon observations and some morning observations. Some of the early morning observations are much brighter than the model results. The increased reflectance can be ascribed to the formation of a water ice shell around the dust particles, thus creating the water ice clouds which Colburn et al. [1989], among others, have predicted.

  18. Absorption and scattering properties of the Martian dust in the solar wavelengths.

    PubMed

    Ockert-Bell, M E; Bell JF 3rd; Pollack, J B; McKay, C P; Forget, F

    1997-04-25

    A new wavelength-dependent model of the single-scattering properties of the Martian dust is presented. The model encompasses the solar wavelengths (0.3 to 4.3 micrometers at 0.02 micrometer resolution) and does not assume a particular mineralogical composition of the particles. We use the particle size distribution, shape, and single-scattering properties at Viking Lander wavelengths presented by Pollack et al. [1995]. We expand the wavelength range of the aerosol model by assuming that the atmospheric dust complex index of refraction is the same as that of dust particles in the bright surface geologic units. The new wavelength-dependent model is compared to observations taken by the Viking Orbiter Infrared Thermal Mapper solar channel instrument during two dust storms. The model accurately matches afternoon observations and some morning observations. Some of the early morning observations are much brighter than the model results. The increased reflectance can be ascribed to the formation of a water ice shell around the dust particles, thus creating the water ice clouds which Colburn et al. [1989], among others, have predicted.

  19. Parameterization of the light absorption properties of chromophoric dissolved organic matter in the Baltic Sea and Pomeranian lakes

    NASA Astrophysics Data System (ADS)

    Meler, Justyna; Kowalczuk, Piotr; Ostrowska, Mirosława; Ficek, Dariusz; Zabłocka, Monika; Zdun, Agnieszka

    2016-08-01

    This study presents three alternative models for estimating the absorption properties of chromophoric dissolved organic matter aCDOM(λ). For this analysis we used a database containing 556 absorption spectra measured in 2006-2009 in different regions of the Baltic Sea (open and coastal waters, the Gulf of Gdańsk and the Pomeranian Bay), at river mouths, in the Szczecin Lagoon and also in three lakes in Pomerania (Poland) - Obłęskie, Łebsko and Chotkowskie. The variability range of the chromophoric dissolved organic matter (CDOM) absorption coefficient at 400 nm, aCDOM(400), lay within 0.15-8.85 m-1. The variability in aCDOM(λ) was parameterized with respect to the variability over 3 orders of magnitude in the chlorophyll a concentration Chl a (0.7-119 mg m-3). The chlorophyll a concentration and aCDOM(400) were correlated, and a statistically significant, nonlinear empirical relationship between these parameters was derived (R2 = 0.83). On the basis of the covariance between these parameters, we derived two empirical mathematical models that enabled us to design the CDOM absorption coefficient dynamics in natural waters and reconstruct the complete CDOM absorption spectrum in the UV and visible spectral domains. The input variable in the first model was the chlorophyll a concentration, and in the second one it was aCDOM(400). Both models were fitted to a power function, and a second-order polynomial function was used as the exponent. Regression coefficients for these formulas were determined for wavelengths from 240 to 700 nm at 5 nm intervals. Both approximations reflected the real shape of the absorption spectra with a low level of uncertainty. Comparison of these approximations with other models of light absorption by CDOM demonstrated that our parameterizations were superior (bias from -1.45 to 62 %, RSME from 22 to 220 %) for estimating CDOM absorption in the optically complex waters of the Baltic Sea and Pomeranian lakes.

  20. Re-esterified palm oils, compared to native palm oil, do not alter fat absorption, postprandial lipemia or growth performance in broiler chicks.

    PubMed

    Vilarrasa, E; Tres, A; Bayés-García, L; Parella, T; Esteve-Garcia, E; Barroeta, A C

    2014-08-01

    Re-esterified palm oils are obtained from the chemical esterification of palm acid oils (rich in free fatty acids) with glycerol, both economically interesting by-products from oil refining and biodiesel industries, respectively. Thus, re-esterified palm oils could be an economically interesting alternative to native palm oil in broiler chick diets. However, because they may have different physicochemical properties than have their corresponding native oil, we assessed the effect of fatty acid (FA) positional distribution within acylglycerol molecules and the effect of acylglycerol composition on FA apparent absorption, and their possible consequences on the evolution of postprandial lipemia and growth performance in broiler chicks. Seventy-two 1-day-old female broiler chicks were randomly distributed into 18 cages. The three treatments used were the result of a basal diet supplemented with 6 wt% of native palm oil (N-TAG), re-esterified palm oil (E-TAG), or re-esterified palm oil high in mono- and diacylglycerols (E-MDAG). Chemical esterification raised the fraction of palmitic acid at the sn-2 position from 9.63 mol% in N-TAG oil to 17.9 mol% in E-TAG oil. Furthermore, E-MDAG oil presented a high proportion of mono- (23.1 wt%) and diacylglycerols (51.2 wt%), with FA mainly located at the sn-1,3 positions, which resulted in a lower gross-energy content and an increased solid-fat index at the chicken's body temperature. However, re-esterified palm oils did not alter fat absorption, postprandial lipemia, or growth performance, compared to native palm oil, so they can be used as alternative fat sources in broiler chick diets.

  1. Microwave absorption properties of polyaniline-Fe3O4/ZnO-polyester nanocomposite: Preparation and optimization

    NASA Astrophysics Data System (ADS)

    Dorraji, M. S. Seyed; Rasoulifard, M. H.; Khodabandeloo, M. H.; Rastgouy-Houjaghan, M.; Zarajabad, H. Karimi

    2016-03-01

    New nanocomposites have been successfully prepared based on polyester resin, including various metal oxides (ZnO nanorod bundles, Fe3O4 nanoparticles, and nano Fe3O4/ZnO) and Polyaniline (PANI) synthesized with different dopants. The microwave absorption properties of nanocomposites were investigated in X-band range. The Taguchi experimental design was used to study the effects of the type of metal oxide and that of PANI (doped with various acids) and the weight percent of metal oxide in PANI and that of filler (metal oxide and PANI) in polyester matrix on the microwave absorption properties with the absorber thickness of only 2 mm. The weight percent of metal oxide in PANI was found to be the most significant parameter, accounting for 45.611% of the total contribution of the four selected parameters. Fe3O4/ZnO as inorganic oxide, PTSA as dopant of PANI, 25 wt.% for inorganic oxide in PANI, and filler in the polyester matrix were selected as optimum conditions by Taguchi method. The sample prepared in optimal conditions had reflection loss of less than -10 dB (absorption >90%) and covering a frequency range of 8.4-11.6 GHz.

  2. Morphology evolution, magnetic and microwave absorption properties of nano/submicrometre iron particles obtained at different reduced temperatures

    NASA Astrophysics Data System (ADS)

    Fan, Xi'an; Guan, Jianguo; Wang, Wei; Tong, Guoxiu

    2009-04-01

    Nano/submicrometre iron particles were prepared by a hydrogen reduction method in a fluidized bed furnace using α-FeOOH nanorods as precursors. The effect of the reducing temperature (T) on the microstructure, static magnetic properties, microwave electromagnetic parameters and microwave absorption properties of the resultant iron particles was investigated. When T increases from 450 to 650 °C, the as-obtained iron particles show an obvious morphology evolution from anisotropic nanorods to isotropic submicrometre polyhedra. As a result, the saturation magnetization, the complex permittivity and the real permeability all increase, while the coercivity and the imaginary permeability decrease due to the reducing surface effect and shape anisotropy. Nanocomposites containing 30 wt% iron nanorods obtained at 450 °C show a minimal reflection loss (RL) as low as -36.8 dB at 14.1 GHz and an absorption band with RL under -10 dB from 11.6 to 17.0 GHz when the thickness is 1.5 mm, suggesting that they are promising as a strong absorption, thin and lightweight microwave absorber.

  3. The mechanism and properties of bio-photon emission and absorption in protein molecules in living systems

    NASA Astrophysics Data System (ADS)

    Pang, Xiao-feng

    2012-05-01

    The mechanism and properties of bio-photon emission and absorption in bio-tissues were studied using Pang's theory of bio-energy transport, in which the energy spectra of protein molecules are obtained from the discrete dynamic equation. From the energy spectra, it was determined that the protein molecules could both radiate and absorb bio-photons with wavelengths of <3 μm and 5-7 μm, consistent with the energy level transitions of the excitons. These results were consistent with the experimental data; this consisted of infrared absorption data from collagen, bovine serum albumin, the protein-like molecule acetanilide, plasma, and a person's finger, and the laser-Raman spectra of acidity I-type collagen in the lungs of a mouse, and metabolically active Escherichia coli. We further elucidated the mechanism responsible for the non-thermal biological effects produced by the infrared light absorbed by the bio-tissues, using the above results. No temperature rise was observed; instead, the absorbed infrared light promoted the vibrations of amides as well the transport of the bio-energy from one place to other in the protein molecules, which changed their conformations. These experimental results, therefore, not only confirmed the validity of the mechanism of bio-photon emission, and the newly developed theory of bio-energy transport mentioned above, but also explained the mechanism and properties of the non-thermal biological effects produced by the absorption of infrared light by the living systems.

  4. Light Absorption Properties and Radiative Effects of Primary Organic Aerosol Emissions

    EPA Science Inventory

    Organic aerosols (OA) in the atmosphere affect Earth’s energy budget by not only scattering but also absorbing solar radiation due to the presence of the so-called “brown carbon” (BrC) component. However, the absorptivities of OA are not or poorly represented in current climate m...

  5. Visible absorption properties of radiation exposed XR type-T radiochromic film.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N

    2004-10-01

    The visible absorption spectra of Gafchromic XR type-T radiochromic film have been investigated to analyse the dosimetry characteristics of the film with visible light densitometers. Common densitometers can use photospectrometry, fluorescent light (broad-band visible), helium neon (632 nm), light emitting diode (LED) or other specific bandwidth spectra. The visible absorption spectra of this film when exposed to photon radiation show peaks at 676 nm and 618 nm at 2 Gy absorbed doses which shift to slightly lower wavelengths (662 nm and 612 nm at 8 Gy absorbed dose) at higher doses. This is similar to previous models of Gafchromic film such as MD-55-2 and HS but XR type-T also includes a large absorption at lower visible wavelengths due to 'yellow' dyes placed within the film to aid with visible recognition of the film exposure level. The yellow dye band pass is produced at approximately 520 nm to 550 nm and absorbs wavelengths lower than this value within the visible spectrum. This accounts for the colour change from yellow to brown through the added absorption in the red wavelengths with radiation exposure. The film produces a relatively high dose sensitivity with up to 0.25 OD units per Gy change at 672 nm at 100 kVp x-ray energy. Variations in dose sensitivity can be achieved by varying wavelength analysis.

  6. Nonlinear absorption properties of AlGaAs/GaAs multiple quantum wells grown by metalorganic chemical vapor deposition

    NASA Technical Reports Server (NTRS)

    Lee, Hsing-Chung; Kost, A.; Kawase, M.; Hariz, A.; Dapkus, P. Daniel

    1988-01-01

    The nonlinear absorption properties of the excitonic resonances associated with multiple quantum wells (MQWs) in AlGaAs/GaAs grown by metalorganic chemical vapor deposition are reported. The dependence of the saturation properties on growth parameters, especially growth temperature, and the well width are described. The minimum measured saturation intensity for these materials is 250 W/sq cm, the lowest reported value to date. The low saturation intensities are the result of excellent minority carrier properties. A systematic study of minority carrier lifetimes in quantum wells are reported. Lifetimes range from 50-350 ns depending on growth temperature and well width. When corrected for lateral diffusion effects and the measured minority carrier lifetime, the saturation data suggest that saturation intensities as low as 2.3 W/sq cm can be achieved in this system. The first measurements of the dependence of the exciton area and the magnitude of the excitonic absorption on well width are prsented. The growth of MQW structures on transparent GaP substrates is demonstrated and the electroabsorption properties of these structures are reviewed.

  7. An Analysis of AERONET Aerosol Absorption Properties and Classifications Representative of Aerosol Source Regions

    NASA Technical Reports Server (NTRS)

    Giles, David M.; Holben, Brent N.; Eck, Thomas F.; Sinyuk, Aliaksandr; Smirnov, Alexander; Slutsker, Ilya; Dickerson, R. R.; Thompson, A. M.; Schafer, J. S.

    2012-01-01

    Partitioning of mineral dust, pollution, smoke, and mixtures using remote sensing techniques can help improve accuracy of satellite retrievals and assessments of the aerosol radiative impact on climate. Spectral aerosol optical depth (tau) and single scattering albedo (omega (sub 0) ) from Aerosol Robotic Network (AERONET) measurements are used to form absorption [i.e., omega (sub 0) and absorption Angstrom exponent (alpha(sub abs))] and size [i.e., extinction Angstrom exponent (alpha(sub ext)) and fine mode fraction of tau] relationships to infer dominant aerosol types. Using the long-term AERONET data set (1999-2010), 19 sites are grouped by aerosol type based on known source regions to: (1) determine the average omega (sub 0) and alpha(sub abs) at each site (expanding upon previous work); (2) perform a sensitivity study on alpha(sub abs) by varying the spectral omega (sub 0); and (3) test the ability of each absorption and size relationship to distinguish aerosol types. The spectral omega (sub 0) averages indicate slightly more aerosol absorption (i.e., a 0.0 < delta omega (sub 0) <= 0.02 decrease) than in previous work and optical mixtures of pollution and smoke with dust show stronger absorption than dust alone. Frequency distributions of alpha(sub abs) show significant overlap among aerosol type categories and at least 10% of the alpha(sub abs) retrievals in each category are below 1.0. Perturbing the spectral omega (sub 0) by +/- 0.03 induces significant alpha(sub abs) changes from the unperturbed value by at least approx. +/- 0.6 for Dust, approx. +/-0.2 for Mixed, and approx. +/-0.1 for Urban/Industrial and Biomass Burning. The omega (sub 0)440nm and alpha(sub ext) 440-870nm relationship shows the best separation among aerosol type clusters, providing a simple technique for determining aerosol type from surface- and future space-based instrumentation.

  8. Electric field modulation of magnetic anisotropy and microwave absorption properties in Fe50Ni50/Teflon composite films

    NASA Astrophysics Data System (ADS)

    Xia, Zhenjun; He, Jun; Ou, Xiulong; Wang, Yu; He, Shuli; Zhao, Dongliang; Yu, Guanghua

    2016-05-01

    Fe50Ni50 nanoparticle films with the size about 6 nm were deposited by a high energetic cluster deposition source. An electric field of about 0 - 40 kV was applied on the sample platform when the films were prepared. The field assisted deposition technique can dramatically induce in-plane magnetic anisotropy. To probe the microwave absorption properties, the Fe50Ni50 nanoparticles were deliberately deposited on the dielectric Teflon sheet. Then the laminated Fe50Ni50/Teflon composites were used to do reflection loss scan. The results prove that the application of electric field is an effective avenue to improve the GHz microwave absorption performance of our magnetic nanoparticles films expressed by the movement of reflection loss peak to high GHz region for the composites.

  9. Properties of the Carrol system and a machine design for solar-powered, air cooled, absorption space cooling

    NASA Astrophysics Data System (ADS)

    1981-05-01

    The name Carrol was selected as a convenient shorthand designation for a prime candidate chemical system comprising ethylene glycol-lithium bromide as an absorbent mixture with water as a refrigerant. The instrumentation, methods of handling data and numerical results from a systematic determination of Carrol property data required to design an air cooled absorption machine based on this chemical system are described. These data include saturation temperature, relative enthalpy, density, specific heat capacity, thermal conductivity, viscosity and absorber film heat transfer coefficient as functions of solution temperature and Carrol concentration over applicable ranges. For each of the major components of the absorption chiller, i.e., generator, chiller, absorber, condenser, heat exchanger, purge and controls, the report contains an assembly drawing and the principal operating characteristics of that component.

  10. Flaky FeSiAl alloy-carbon nanotube composite with tunable electromagnetic properties for microwave absorption

    PubMed Central

    Huang, Lina; Liu, Xiaofang; Chuai, Dan; Chen, Yaxin; Yu, Ronghai

    2016-01-01

    Flaky FeSiAl alloy/multi-wall carbon nanotube (FeSiAl/MWCNT) composite was fabricated by facile and scalable ball milling method. The morphology and electromagnetic properties of the FeSiAl alloy can be well tuned by controlling the milling time. It is found that the magnetic loss of the FeSiAl alloy is improved by optimizing the milling time due to the increased anisotropy field. Meanwhile the addition of MWCNTs enhances the dielectric loss of the composite by increasing the interfacial polarizations, dipolar polarizations and conductive paths. Relative to conventional FeSiAl absorbers, the FeSiAl/MWCNT composite exhibits greatly improved microwave absorption performance with advantages of strong absorption and small thickness. The minimum reflection loss of the composite reaches −42.8 dB at 12.3 GHz at a very thin thickness of 1.9 mm. PMID:27762327

  11. The dependence of C IV broad absorption line properties on accompanying Si IV and Al III absorption: relating quasar-wind ionization levels, kinematics, and column densities

    SciTech Connect

    Filiz Ak, N.; Brandt, W. N.; Schneider, D. P.; Trump, J. R.; Hall, P. B.; Anderson, S. F.; Hamann, F.; Myers, Adam D.; Pâris, I.; Petitjean, P.; Ross, Nicholas P.; Shen, Yue; York, Don

    2014-08-20

    We consider how the profile and multi-year variability properties of a large sample of C IV Broad Absorption Line (BAL) troughs change when BALs from Si IV and/or Al III are present at corresponding velocities, indicating that the line of sight intercepts at least some lower ionization gas. We derive a number of observational results for C IV BALs separated according to the presence or absence of accompanying lower ionization transitions, including measurements of composite profile shapes, equivalent width (EW), characteristic velocities, composite variation profiles, and EW variability. We also measure the correlations between EW and fractional-EW variability for C IV, Si IV, and Al III. Our measurements reveal the basic correlated changes between ionization level, kinematics, and column density expected in accretion-disk wind models; e.g., lines of sight including lower ionization material generally show deeper and broader C IV troughs that have smaller minimum velocities and that are less variable. Many C IV BALs with no accompanying Si IV or Al III BALs may have only mild or no saturation.

  12. Two-Photon Absorption Properties of Proquinoidal D-A-D and A-D-A Quadrupolar Chromophores

    PubMed Central

    Susumu, Kimihiro; Fisher, Jonathan A. N.; Zheng, Jieru

    2011-01-01

    We report the synthesis, one- and two-photon absorption spectroscopy, fluorescence, and electrochemical properties of a series of quadrupolar molecules that feature proquinoidal π-aromatic acceptors. These quadrupolar molecules possess either donor-acceptor-donor (D–A–D) or acceptor-donor-acceptor (A–D–A) electronic motifs, and feature 4-N,N-dihexylaminophenyl, 4-dodecyloxyphenyl, 4-(N,N-dihexylamino)benzo[c][1,2,5]thiadiazolyl or 2,5-dioctyloxyphenyl electron donor moieties and benzo[c][1,2,5]thiadiazole (BTD) or 6,7-bis(3’,7’-dimethyloctyl)[1,2,5]thiadiazolo[3,4-g]quinoxaline (TDQ) electron acceptor units. These conjugated structures are highly emissive in nonpolar solvents and exhibit large spectral red-shifts of their respective lowest energy absorption bands relative to analogous reference compounds that incorporate phenylene components in place of BTD and TDQ moieties. BTD-based D-A-D and A-D-A chromophores exhibit increasing fluorescence emission red-shifts, and a concomitant decrease of the fluorescence quantum yield (Φf) with increasing solvent polarity; these data indicate that electronic excitation augments benzothiadiazole electron density via an internal charge transfer mechanism. The BTD- and TDQ-containing structures exhibit blue-shifted two-photon absorption (TPA) spectra relative to their corresponding one-photon absorption (OPA) spectra, and display high TPA cross-sections (>100 GM) within these spectral windows. D-A-D and A-D-A structures that feature more extensive conjugation within this series of compounds exhibit larger TPA cross-sections consistent with computational simulation. Factors governing TPA properties of these quadrupolar chromophores are discussed within the context of a three-state model. PMID:21568299

  13. A method for segregating the optical absorption properties and the mass concentration of winter time urban aerosol

    NASA Astrophysics Data System (ADS)

    Ajtai, T.; Utry, N.; Pintér, M.; Major, B.; Bozóki, Z.; Szabó, G.

    2015-12-01

    A novel in-situ, real time method for the determination of inherent absorption properties of light absorbing carbonaceous particulate matter and its possible application for source apportionment are introduced here. The method is deduced from a two-week campaign under wintry urban conditions during which strong correlation was found between aerosol number size distribution and wavelength dependent optical absorption coefficient (AOC(λ)), measured by a Single Mobility Particle Sizer (SMPS) and a multi-wavelength photoacoustic absorption spectrometer, respectively, while wood burning and traffic (i.e. fossil fuel burning) activity were identified to be the dominant sources of carbonaceous particulate. Indeed, during the whole campaign, regardless of the actual emission strength of the aerosol sources, the measured number size distributions were always dominated by two unimodal modes with Count Mean Diameter (CMD) of 20 and 100 nm, which could be correlated to traffic and wood burning activities, respectively. AAEff, AAEwb (i.e. the Aerosol Angström Exponent of traffic and wood burning aerosol, respectively), σff(266 nm), σff(1064 nm), σwb(266 nm) and σff(1064 nm) (i.e. the segregated mass specific optical absorption coefficients at two of the measurement wavelengths) were found to be 1.17 ± 0.18, 2.6 ± 0.14, 7.3 ± 0.3 m2g-1, 1.7 ± 0.1 m2g-1 3.4 ± 0.3 m2g-1 and 0.31 ± 0.08 m2g-1, respectively. Furthermore the introduced methodology can also disentangle and quantify the temporal variation of both the segregated optical absorptions and the segregated mass concentrations of traffic and wood burning aerosol. Accordingly, the contribution of wood burning to optical absorption of PM was found to be negligible at 1064 nm but increased gradually towards the shorter wavelengths and became commensurable with the optical absorption of traffic at 266 nm during the whole measurement period. Furthermore, the contribution of wood burning mass to CM (mass of carbonaceous

  14. Preparation of Few-Layer Bismuth Selenide by Liquid-Phase-Exfoliation and Its Optical Absorption Properties

    PubMed Central

    Sun, Liping; Lin, Zhiqin; Peng, Jian; Weng, Jian; Huang, Yizhong; Luo, Zhengqian

    2014-01-01

    Bismuth selenide (Bi2Se3), a new topological insulator, has attracted much attention in recent years owing to its relatively simple band structure and large bulk band gap. Compared to bulk, few-layer Bi2Se3 is recently considered as a highly promising material. Here, we use a liquid-phase exfoliation method to prepare few-layer Bi2Se3 in N-methyl-2-pyrrolidone or chitosan acetic solution. The resulted few-layer Bi2Se3 dispersion demonstrates an interesting absorption in the visible light region, which is different from bulk Bi2Se3 without any absorption in this region. The absorption spectrum of few-layer Bi2Se3 depends on its size and layer number. At the same time, the nonlinear and saturable absorption of few-layer Bi2Se3 thin film in near infrared is also characterized well and further exploited to generate laser pulses by a passive Q-switching technique. Stable Q-switched operation is achieved with a lower pump threshold of 9.3 mW at 974 nm, pulse energy of 39.8 nJ and a wide range of pulse-repetition-rate from 6.2 to 40.1 kHz. Therefore, the few-layer Bi2Se3 may excite a potential applications in laser photonics and optoelectronic devices. PMID:24762534

  15. Visible light absorption and photo-sensitizing properties of spinach leaves and beetroot extracted natural dyes.

    PubMed

    Sengupta, D; Mondal, B; Mukherjee, K

    2015-09-01

    Herein, chlorophyll and betalain dyes are extracted from fresh spinach leaves and beetroots. Fourier transform infrared spectra are used to identify the characteristic peaks of the extracted dyes. UV-vis light absorption characteristics of the dyes and their mixed counterpart are investigated by varying their pH and temperature. These dyes are used as photo sensitizer for fabrication of zinc oxide photo-anode based dye sensitized solar cells (DSSCs). The photo-voltaic characteristics of the developed DSSCs are measured under simulated solar light (power of incident light 100 mW cm(-2) from Air Mass 1.5G). The solar to electric conversion efficiencies for the chlorophyll, betalain and mixed dye based solar cells are estimated as 0.148%, 0.197% and 0.294% respectively. The highest conversion efficiency for mixed dye based solar cell is attributed due to the absorption of wider range of solar spectrum.

  16. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1986-01-01

    After long arduous work with the simulator, measurements of the refractivity and absorptivity of nitrogen under conditions similar to those for Titan were completed. The most significant measurements, however, were those of the microwave absorption from gaseous ammonia under simulated conditions for the Jovian atmospheres over wavelengths from 1.3 to 22 cm. The results of these measurements are critical in that they confirm the theoretical calculation of the ammonia opacity using the Ben-Reuven lineshape. The application of both these results, and results obtained previously, to planetary observations at microwave frequencies were especially rewarding. Applications of the results for ammonia to radio astronomical observations of Jupiter in the 1.3 to 20 cm wavelength range and the application of results for gaseous H2SO4 under simulated Venus conditions are discussed.

  17. Absorption of Carotenoids and Mechanisms Involved in Their Health-Related Properties.

    PubMed

    Cervantes-Paz, Braulio; Victoria-Campos, Claudia I; Ornelas-Paz, José de Jesús

    2016-01-01

    Carotenoids participate in the normal metabolism and function of the human body. They are involved in the prevention of several diseases, especially those related to the inflammation syndrome. Their main mechanisms of action are associated to their potent antioxidant activity and capacity to regulate the expression of specific genes and proteins. Recent findings suggest that carotenoid metabolites may explain several processes where the participation of their parent carotenoids was unclear. The health benefits of carotenoids strongly depend on their absorption and transformation during gastrointestinal digestion. The estimation of the 'bioaccessibility' of carotenoids through in vitro models have made possible the evaluation of the effect of a large number of factors on key stages of carotenoid digestion and intestinal absorption. The bioaccessibility of these compounds allows us to have a clear idea of their potential bioavailability, a term that implicitly involves the biological activity of these compounds. PMID:27485232

  18. Visible light absorption and photo-sensitizing properties of spinach leaves and beetroot extracted natural dyes

    NASA Astrophysics Data System (ADS)

    Sengupta, D.; Mondal, B.; Mukherjee, K.

    2015-09-01

    Herein, chlorophyll and betalain dyes are extracted from fresh spinach leaves and beetroots. Fourier transform infrared spectra are used to identify the characteristic peaks of the extracted dyes. UV-vis light absorption characteristics of the dyes and their mixed counterpart are investigated by varying their pH and temperature. These dyes are used as photo sensitizer for fabrication of zinc oxide photo-anode based dye sensitized solar cells (DSSCs). The photo-voltaic characteristics of the developed DSSCs are measured under simulated solar light (power of incident light 100 mW cm-2 from Air Mass 1.5G). The solar to electric conversion efficiencies for the chlorophyll, betalain and mixed dye based solar cells are estimated as 0.148%, 0.197% and 0.294% respectively. The highest conversion efficiency for mixed dye based solar cell is attributed due to the absorption of wider range of solar spectrum.

  19. Facile synthesis of RGO/NiO composites and their excellent electromagnetic wave absorption properties

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Tian, Xingyou; Wang, Cuiping; Luo, Hailong; Hu, Jie; Shen, Yuhua; Xie, Anjian

    2014-09-01

    Reduced graphene oxide/NiO composite (RGO/NiO) was synthesized by a facile pyrolyzation process. The NiO nanoparticles with a small size of about 10-50 nm are uniformly dispersed onto the thin graphene nanosheets. The as-prepared RGO/NiO composite shows excellent microwave absorbability. The obtained composite with a coating layer thickness of 3.5 mm exhibits a maximum absorption of -55.5 dB at 10.6 GHz. And in particular, the product with a coating layer thickness of only 3.0 mm possesses a bandwidth of 6.7 GHz (from frequency of 10.2 to 16.9 GHz) corresponding to reflection loss at -10 dB (90% absorption). Thus, the as-prepared RGO/NiO composite is a very promising EM wave absorbing material as lightweight and high-performance.

  20. The dust, nebular emission, and dependence on QSO radio properties of the associated Mg II absorption line systems

    SciTech Connect

    Khare, Pushpa; Daniel, Vanden Berk; Rahmani, Hadi; York, Donald G.

    2014-10-10

    We studied dust reddening and [O II] emission in 1730 Mg II associated absorption systems (AAS; relative velocity with respect to QSOs, ≤3000 km s{sup –1}; in units of velocity of light, β, ≤0.01) with 0.4 ≤z {sub abs} ≤ 2 in the Sloan Digital Sky Survey DR7, focusing on their dependence on the radio and other QSO properties. We used control samples, several with matching radio properties, to show that (1) AAS in radio-detected (RD) QSOs cause 2.6 ± 0.2 times higher dust extinction than those in radio-undetected (RUD) ones, which in turn cause 2.9 ± 0.7 times the dust extinction in the intervening systems; (2) AAS in core-dominated QSOs cause 2.0 ± 0.1 times higher dust extinction than those in lobe-dominated QSOs; (3) the occurrence of AAS is 2.1 ± 0.2 times more likely in RD QSOs than in RUD QSOs and 1.8 ± 0.1 time more likely in QSOs having black holes with masses larger than 1.23 × 10{sup 9} M {sub ☉} than in those with lower-mass black holes; and (4) there is excess flux in [O II]λ3727 emission in the composite spectra of the AAS samples compared with those of the control samples, which is at the emission redshift. The presence of AAS enhances the O II emission from the active galactic nucleus and/or the host galaxy. This excess is similar for both RD and RUD samples and is 2.5 ± 0.4 times higher in lobe-dominated samples than in core-dominated samples. The excess depends on the black hole mass and Eddington ratio. All these point to the intrinsic nature of the AAS except for the systems with z {sub abs} > z {sub em}, which could be infalling galaxies.

  1. Electromagnetic Property and Tunable Microwave Absorption of 3D Nets from Nickel Chains at Elevated Temperature.

    PubMed

    Liu, Jia; Cao, Mao-Sheng; Luo, Qiang; Shi, Hong-Long; Wang, Wen-Zhong; Yuan, Jie

    2016-08-31

    We fabricated the nickel chains by a facile wet chemical method. The morphology of nickel chains were tailored by adjusting the amount of PVP during the synthesis process. Both the complex permittivity and permeability of the three-dimensional (3D) nets constructed by nickel chains present strong dependences on temperature in the frequency range of 8.2-12.4 GHz and temperature range of 323-573 K. The peaks in imaginary component of permittivity and permeability mainly derive from interfacial polarizations and resonances, devoting to dielectric and magnetic loss, respectively. The effect from both dielectric and magnetism contribute to enhancing the microwave absorption. The maximum absorption value of the 3D nickel chain nets is approximately -50 dB at 8.8 GHz and 373 K with a thickness of 1.8 mm, and the bandwidth less than -10 dB almost covers the whole investigated frequency band. These are encouraging findings, which provide the potential advantages of magnetic transition metal-based materials for microwave absorption application at elevated temperature. PMID:27509241

  2. The compositions, surface texture, absorption, and binding properties of fly ash in China

    SciTech Connect

    Ma, B.; Qi, M.; Peng, J.; Li, Z.

    1999-05-01

    The compositions, particle distribution, and surface textures of fly ashes from various sources in China were investigated by means of a laser scanning particles distribution meter, a nitrogen absorption meter, scanning electronic microscopy, mercury intrusion porosimetry, and x-ray diffraction tests. Based on the test results, the absorption and binding mechanism of fly ash on Ca{sup 2+}, Na{sup +}, OH{sup {minus}}, Cl{sup {minus}}, and Cr{sup 3+} ions were studied. The study showed that particle distribution of fly ash depends on the type of coal and its combustion conditions. The fly ashes investigated in the present investigation are formed of amorphous or glassy structures. Fly ashes also have large specific surface and special texture, and have fairly good absorption and binding capability on Ca{sup 2+}, Na{sup +}, OH{sup {minus}}, Cl{sup {minus}}, and Cr{sup 3+} ions. This conclusion is important to wide application of fly ash in the future.

  3. Influence of pH, O/sub 2/, and temperature on the absorption properties of the secondary light-harvesting antenna in members of the family Rhodospirillaceae

    SciTech Connect

    Uffen, R.L.

    1985-09-01

    Results show that holochrome B800-860 (LH II) exhibits unstable light absorption properties in whole cells. This was observed in Rhodopseudomonas capsulata grown anaerobically in light in weakly buffered carbohydrate medium. The whole cell spectrophotometric changes were attributed to mild acid conditions generated during sugar metabolism. LH II absorbency was also destroyed in both R. capsulata and Rhodopseudomonas gelatinosa when cultures growing at neutral pH were acidified to a pH value around 5.0. In contrast, during the same time period of exposure to pH 5.0, only a 50% decrease in Rhodopseudomonas sphaeroides LH II B800 absorbency was measured. At neutral pH, LH II absorbency in suspensions of nongrowing Rhodopseudomonas spp. was also sensitive to O/sub 2/ exposure and to incubation at 30 to 40/sup 0/C. During treatment with O/sub 2/, the rate of LH II B800 absorption decrease in R. gelatinosa and R. sphaeroides was 60 and 40% per h, respectively, compared with their absorbency maximum around 860 nm. Both 860-nm absorbency and the total bacteriochlorophyll content of the cells remained unchanged. On the other hand, no significant decrease in B800 of LH II in R. capsulata occurred during O/sub 2/ exposure, but a 20% absorption decay rate per h of B800 was observed in cells incubated anaerobically at 40/sup 0/C. The near-infrared absorption spectrum of Rhodospirillum rubrum, which does not form LH II, was not significantly influenced by these different pH, aerobic, or temperature conditions.

  4. Microwave absorption properties and infrared emissivities of ordered mesoporous C-TiO{sub 2} nanocomposites with crystalline framework

    SciTech Connect

    Wang, Tao; He, Jianping; Zhou, Jianhua; Tang, Jing; Guo, Yunxia; Ding, Xiaochun; Wu, Shichao; Zhao, Jianqing

    2010-12-15

    Ordered mesoporous C-TiO{sub 2} nanocomposites with crystalline framework were prepared by the evaporation-induced triconstituent co-assembly method. The products were characterized by XRD, TEM, N{sub 2} adsorption-desorption and TG. Their microwave absorption properties were investigated by mixing the product and epoxy resin. It is found that the peak with minimum reflection loss value moves to lower frequencies and the ordered mesoporous C-TiO{sub 2} nanocomposite possesses an excellent microwave absorbing property with the maximum reflection loss of -25.4 dB and the bandwidth lower than -10 dB is 6.6 GHz. The attenuation of microwave can be attributed to dielectric loss and their absorption mechanism is discussed in detail. The mesoporous C-TiO{sub 2} nanocomposites also exhibit a lower infrared emissivity in the wavelength from 8 to 14 {mu}m than that of TiO{sub 2}-free powder. -- Graphical abstract: Ordered mesoporous C-TiO{sub 2} nanocomposite with crystalline framework possess excellent microwave absorbing properties with the maximum reflection loss of -25.4 dB and the bandwidth lower than -10 dB is 6.6 GHz. Display Omitted

  5. The effects of pH and surfactants on the absorption and fluorescence properties of ochratoxin A and zearalenone.

    PubMed

    Li, Taihua; Kim, Bo Bae; Ha, Tae Hwan; Shin, Yong-Beom; Kim, Min-Gon

    2015-11-01

    The pH and surfactant dependencies of the absorption and fluorescence properties of ochratoxin A (OTA) and zearalenone (ZEN), the main mycotoxins found as contaminants in foods and feeds, were evaluated. Three surfactants with different ionic properties were investigated, namely sodium dodecyl sulfate (SDS, anionic), Tween 20 (nonionic) and hexadecyltrimethylammonium bromide (CTAB, cationic). The results show that the effects of pH on the absorption wavelength maxima and fluorescence efficiencies of the mycotoxins, which are a consequence of the presence of acidic phenol and/or carboxyl containing fluorophores, are dependent on the ionic nature of the added surfactants. Specifically, the fluorescence responses to pH changes of OTA and ZEN are similar in the presence or absence of Tween 20 and SDS. By contrast, the pH-dependent fluorescence properties of these mycotoxins are altered when CTAB is present in the solutions. Moreover, unlike OTA, ZEN in aqueous solution displays almost no fluorescence. However, fluorescence enhancement takes place when surfactants are present in aqueous solutions of this mycotoxin. The results of this study demonstrate that the different microenvironments, present in the organized micellar systems created by the individual surfactants, can be potentially employed to modulate the sensitivities and selectivities of the fluorescence detection of OTA or ZEN.

  6. Does volumetric absorptive microsampling eliminate the hematocrit bias for caffeine and paraxanthine in dried blood samples? A comparative study.

    PubMed

    De Kesel, Pieter M M; Lambert, Willy E; Stove, Christophe P

    2015-06-30

    Volumetric absorptive microsampling (VAMS) is a novel sampling technique that allows the straightforward collection of an accurate volume of blood (approximately 10μL) from a drop or pool of blood by dipping an absorbent polymeric tip into it. The resulting blood microsample is dried and analyzed as a whole. The aim of this study was to evaluate the potential of VAMS to overcome the hematocrit bias, an important issue in the analysis of dried blood microsamples. An LC-MS/MS method for analysis of the model compounds caffeine and paraxanthine in VAMS samples was fully validated and fulfilled all pre-established criteria. In conjunction with previously validated procedures for dried blood spots (DBS) and blood, this allowed us to set up a meticulous comparative study in which both compounds were determined in over 80 corresponding VAMS, DBS and liquid whole blood samples. These originated from authentic human patient samples, covering a wide hematocrit range (0.21-0.50). By calculating the differences with reference whole blood concentrations, we found that analyte concentrations in VAMS samples were not affected by a bias that changed over the evaluated hematocrit range, in contrast to DBS results. However, VAMS concentrations tend to overestimate whole blood concentrations, as a consistent positive bias was observed. A different behavior of VAMS samples prepared from incurred and spiked blood, combined with a somewhat reduced recovery of caffeine and paraxanthine from VAMS tips at high hematocrit values, an effect that was not observed for DBS using a very similar extraction procedure, was found to be at the basis of the observed VAMS-whole blood deviations. Based on this study, being the first in which the validity and robustness of VAMS is evaluated by analyzing incurred human samples, it can be concluded that VAMS effectively assists in eliminating the effect of hematocrit. PMID:26041521

  7. Does volumetric absorptive microsampling eliminate the hematocrit bias for caffeine and paraxanthine in dried blood samples? A comparative study.

    PubMed

    De Kesel, Pieter M M; Lambert, Willy E; Stove, Christophe P

    2015-06-30

    Volumetric absorptive microsampling (VAMS) is a novel sampling technique that allows the straightforward collection of an accurate volume of blood (approximately 10μL) from a drop or pool of blood by dipping an absorbent polymeric tip into it. The resulting blood microsample is dried and analyzed as a whole. The aim of this study was to evaluate the potential of VAMS to overcome the hematocrit bias, an important issue in the analysis of dried blood microsamples. An LC-MS/MS method for analysis of the model compounds caffeine and paraxanthine in VAMS samples was fully validated and fulfilled all pre-established criteria. In conjunction with previously validated procedures for dried blood spots (DBS) and blood, this allowed us to set up a meticulous comparative study in which both compounds were determined in over 80 corresponding VAMS, DBS and liquid whole blood samples. These originated from authentic human patient samples, covering a wide hematocrit range (0.21-0.50). By calculating the differences with reference whole blood concentrations, we found that analyte concentrations in VAMS samples were not affected by a bias that changed over the evaluated hematocrit range, in contrast to DBS results. However, VAMS concentrations tend to overestimate whole blood concentrations, as a consistent positive bias was observed. A different behavior of VAMS samples prepared from incurred and spiked blood, combined with a somewhat reduced recovery of caffeine and paraxanthine from VAMS tips at high hematocrit values, an effect that was not observed for DBS using a very similar extraction procedure, was found to be at the basis of the observed VAMS-whole blood deviations. Based on this study, being the first in which the validity and robustness of VAMS is evaluated by analyzing incurred human samples, it can be concluded that VAMS effectively assists in eliminating the effect of hematocrit.

  8. [Comparative Study on the Molecular Structures and Spectral Properties of Ponceau 4R and Amaranth].

    PubMed

    Zhang, Yong; Chen, Guo-qing; Zhu, Chun; Hu, Yang-jun

    2015-11-01

    The Edinburgh FLS920P steady-instantaneous fluorescence spectrometer was applied on the detection of the absorption and the emission spectra of ponceau 4R and amaranth, which are isomers to each other. After that, the spectral parameters of them were compared. Then, the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used on the optimization of ponceau 4R and amaranth under the ground and excited state, respectively, in order to compare the differences in configurations of them under different states. On the base of the results above, the absorption and emission spectra of the two isomers were calculated with TD-DFT, and the polarized continuum model (PCM) was applied on the base of 6-311++G (d, p). The fluorescence mechanism, the relationships between the properties of fluorescence spectra and the molecular geometry were all analyzed. The results shows that, the structures of the two molecules are non-planar, these two naphthalene rings are not co-planar, respectively, and there's hydrogen bond in amaranth. When the two isomers were on the ground state, the planarity of the naphthalene ring which exists the hydrogen bond mentioned above in amaranth is better than the corresponding part of ponceau 4R. The two isomers are nearly co-planar when they're on the excited state. The molecular structures of ponceau 4R and amaranth optimized above are basically reasonable, for the quantum chemistry calculation spectral results are agree with the experiments. The planarity of the naphthalene rings on the right side in ponceau 4R is worse than that in amaranth, the ponceau 4R molecule experienced more vibration and rotation from the excited to the ground state, lost more energy, which lead to the reduction of energy for emitting fluorescent photons. So ponceau 4R has longer fluorescence emission wave- length than amaranth. In this paper, the molecular structure information of ponceau 4R and amaranth were obtained, and the differences

  9. [Comparative Study on the Molecular Structures and Spectral Properties of Ponceau 4R and Amaranth].

    PubMed

    Zhang, Yong; Chen, Guo-qing; Zhu, Chun; Hu, Yang-jun

    2015-11-01

    The Edinburgh FLS920P steady-instantaneous fluorescence spectrometer was applied on the detection of the absorption and the emission spectra of ponceau 4R and amaranth, which are isomers to each other. After that, the spectral parameters of them were compared. Then, the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used on the optimization of ponceau 4R and amaranth under the ground and excited state, respectively, in order to compare the differences in configurations of them under different states. On the base of the results above, the absorption and emission spectra of the two isomers were calculated with TD-DFT, and the polarized continuum model (PCM) was applied on the base of 6-311++G (d, p). The fluorescence mechanism, the relationships between the properties of fluorescence spectra and the molecular geometry were all analyzed. The results shows that, the structures of the two molecules are non-planar, these two naphthalene rings are not co-planar, respectively, and there's hydrogen bond in amaranth. When the two isomers were on the ground state, the planarity of the naphthalene ring which exists the hydrogen bond mentioned above in amaranth is better than the corresponding part of ponceau 4R. The two isomers are nearly co-planar when they're on the excited state. The molecular structures of ponceau 4R and amaranth optimized above are basically reasonable, for the quantum chemistry calculation spectral results are agree with the experiments. The planarity of the naphthalene rings on the right side in ponceau 4R is worse than that in amaranth, the ponceau 4R molecule experienced more vibration and rotation from the excited to the ground state, lost more energy, which lead to the reduction of energy for emitting fluorescent photons. So ponceau 4R has longer fluorescence emission wave- length than amaranth. In this paper, the molecular structure information of ponceau 4R and amaranth were obtained, and the differences

  10. Unveiling the X-ray/UV properties of AGN winds using Broad and mini-Broad Absorption Line Quasars

    NASA Astrophysics Data System (ADS)

    Giustini, M.

    2015-07-01

    BAL/mini-BALs are observed in the UV spectra of ˜ 20-30% of optically selected AGN as broad absorption troughs blueshifted by several thousands km/s, indicative of powerful nuclear winds. They could be representative of the average AGN if their winds cover only 20-30% of the continuum source, and/or represent an evolutionary state analogous to the high-soft state of BHB, when the jet emission is quenched and strong X-ray absorbing equatorial disk winds are virtually ubiquitous. High-quality, possibly time-resolved X-ray/UV studies are crucial to assess the global amount and 'character' of absorption in BAL/mini-BAL QSOs and to constrain the physical mechanism responsible for the launch and acceleration of their winds, therefore placing them in the broader context of AGN geometry and evolution. I will review here the known X-ray properties of BAL/mini-BAL QSOs, and present new results from a comprehensive X-ray spectral analysis of all the Palomar-Green BAL/mini-BAL QSOs with available XMM-Newton observations, for a total of 51 pointings of 14 different sources. These will include the most recent results from a high-quality simultaneous XMM/HST observational campaign on the mini-BAL QSO PG 1126-041, that unveiled with stunning details the X-ray/UV connection in action in an AGN disk wind through correlated X-ray/UV absorption variability.

  11. Microwave absorption properties of 50% SrFe12O19-50% TiO2 nanocomposites with porosity

    NASA Astrophysics Data System (ADS)

    Dadfar, M. R.; ebrahimi, S. A. Seyyed; Dadfar, M.

    2012-12-01

    SrFe12O19-TiO2 nanocomposites are usually used for absorbing microwaves in military and civil applications. In this work, microwave absorption properties of porous SrFe12O19 nanocomposites with 50% weight ratio of TiO2 have been investigated. 50% TiO2-50% SrFe12O19 nanocomposites were prepared by a controlled hydrolysis of titanium tetraisopropoxide in which SrFe12O19 nanoparticles were synthesized by a sol-gel auto combustion route. The morphology, crystalline structure and crystallite size of SrFe12O19-TiO2 nanocomposites were characterized by field emission scanning electron microscopy and X-ray powder diffraction. The magnetic measurements were carried out with a vibrating sample magnetometer. The microwave absorption was measured by a Vector Network Analyzer. The microwave absorption results indicated that the reflection losses for specimens with 52%-56% porosity and thicknesses of 1.8, 2.1 and 2.6 mm were not very low but minimum reflection loss for a specimen with 4.2 mm thickness reached upto -33 dB.

  12. Optical absorption measurements and quantum-chemical simulations of optical properties of novel fluoro derivatives of pyrazoloquinoline

    NASA Astrophysics Data System (ADS)

    Brik, M. G.; Kuznik, W.; Gondek, E.; Kityk, I. V.; Uchacz, T.; Szlachcic, P.; Jarosz, B.; Plucinski, K. J.

    2010-05-01

    The results of experimental research and quantum-chemical simulations of the absorption spectra of 1-(4-fluorophenyl)-3,4-diphenyl, 3-(4-fluorophenyl)-1,4-diphenyl, and 4-(4-fluorophenyl)-1,3-diphenyl-pyrazolo[3,4- b] quinoline are presented. Although the fluorine atom is located on different phenyl rings in these molecules, the absorption spectra do not differ significantly. Semi-empirical AM1, PM3 and RM1 methods, as well as ab initio ADF code-based calculations were used to optimize geometry, calculate the infrared and visible spectra of the afore mentioned compounds and analyze the molecular orbitals schemes. The results of calculations are in good agreement with the experimental data. It was also demonstrated that the positions of the fluorescence maxima depend significantly on the solvent (contrary to the absorption spectra), in which the molecules are embedded, which allows for manipulating with fluorescence properties of the synthesized molecules by changing the solvent.

  13. Controlled synthesis and microwave absorption properties of Ni0.6Zn0.4Fe2O4/PANI composite via an in-situ polymerization process

    NASA Astrophysics Data System (ADS)

    Wang, Min; Ji, Guangbin; Zhang, Baoshan; Tang, Dongming; Yang, Yi; Du, Youwei

    2015-03-01

    The binary composites of conducting polyaniline (PANI) and nickle zinc ferrite were synthesized by an in-situ polymerization process, and the electromagnetic absorption properties of the composites were also investigated. The FT-IR spectra present the peaks of PANI (1562, 1481, 1301, 1109, and 799 cm-1) and the bonds of NiZn ferrite (579 and 390 cm-1), indicating the existence of both NiZn ferrite particles and PANI in the composites. With the increasing ratio of nickle zinc ferrite, the composites distributes in irregular compared with pure PANI and Ni0.6Zn0.4Fe2O4. The TG curves of the pure PANI and PANI/Ni0.6Zn0.4Fe2O4 composites with different molar ratios clearly show the increase percentage of the ferrite in the composites. Furthermore, we found that the excellent electromagnetic absorption properties and wide absorption bandwidth can be achieved by adjusting proper molar ratios Ni0.6Zn0.4Fe2O4 to PANI. The maximum reflection loss of Ni0.6Zn0.4Fe2O4/PANI can reach to -41 dB at 12.8 GHz and the bandwidth exceeding -10 dB can reach to 5 GHz with the absorber thickness of 2.6 mm at the molar ratio of 1:2. This can be attributed to the enhancing magnetic loss and the better impedance matching. Therefore, Ni0.6Zn0.4Fe2O4/PANI ferrite composites can become a new kind of candidate in the field of the microwave absorbing.

  14. The Hubble Space Telescope quasar absorption line key project. 6: Properties of the metal-rich systems

    NASA Technical Reports Server (NTRS)

    Bergeron, Jacqueline; Petitjean, Patrick; Sargent, W. L. W.; Bahcall, John N.; Boksenberg, Alec; Hartig, George F.; Jannuzi, Buell T.; Kirhakos, Sofia; Savage, Blair D.; Schneider, Donald P.

    1994-01-01

    We present an analysis of the properties of a sample of 18 metal-rich, low-redshift z(sub abs) much less than z(sub em) absorbers seen in low- and medium-resolution spectra obtained for the Quasar Absorption Line Key Project with the Hubble Space Telescope Faint Object Spectrograph (HST/FOS). For most of the C IV and Lyman-limit systems, observations in the optical wavelength range of the expected associated Mg II absorption are available. As at high redshift (z approximately 2), there are two subclasses of absorbers which are characterized by the presence or absence of MG II absorption. However, some low-redshift Mg II and Fe absorptions originate from regions optically thin to UV ionizing photons and thus, at low redshift, the low-ionization systems do not always trace high opacities, as is the case at high redshift. This implies that the mean ionization state of metal-rich, optically thin absorbing clouds falls with decreasing redshift, which is consistent with the hypothesis that the gas is photoionized by the metagalactic UV background radiation field. Two main constraints are derived from the analysis of the Lyman-limit sample, assuming photoionization models are valid. First, a low opacity to ionizing photons (tau(sub LL) approximately less than 1), as observed for several Mg II-Fe II systems at z approximately 0.5, sets limits on the ionization level of hydrogen, thus on the total hydrogen column density and the heavy element abundances, (Z/H) approximately -0.5 to -0.3. Second, the dimensions of individual Mg II clouds are smaller than at high redshift by a factor 3-10. At z approximately greater than 0.6, the O VI absorption doublet is detected in four of the five z(sub abs) much less than z(sub em) systems for which the O VI wavelength range has been observed, whereas the associated N V doublet is detected in only two cases. This suggests that the presence of a high-ionization O VI phase is a general property of z approximately 0.6-1 absorption systems

  15. Comparative aspects of the purification and properties of cholinesterases

    PubMed Central

    Augustinsson, Klas-Bertil

    1971-01-01

    Recent years have seen great progress in the purification and characterization of cholinesterases. Investigation has indicated the existence of two principal groups: a fairly homogeneous group of acetylcholinesterases and a group of enzymes that utilize butyrylcholine, propionycholine, or benzoylcholine as substrates and that differ widely in their properties. This paper reviews the different types of cholinesterase and their sources, the importance of a proper choice of substrate in cholinesterase studies, methods for the purification of cholinesterases, and some of the properties of these enzymes. PMID:4938026

  16. Comparative analysis of discrete and continuous absorption weighting estimators used in Monte Carlo simulations of radiative transport in turbid media

    PubMed Central

    Hayakawa, Carole K.; Spanier, Jerome; Venugopalan, Vasan

    2014-01-01

    We examine the relative error of Monte Carlo simulations of radiative transport that employ two commonly used estimators that account for absorption differently, either discretely, at interaction points, or continuously, between interaction points. We provide a rigorous derivation of these discrete and continuous absorption weighting estimators within a stochastic model that we show to be equivalent to an analytic model, based on the radiative transport equation (RTE). We establish that both absorption weighting estimators are unbiased and, therefore, converge to the solution of the RTE. An analysis of spatially resolved reflectance predictions provided by these two estimators reveals no advantage to either in cases of highly scattering and highly anisotropic media. However, for moderate to highly absorbing media or isotropically scattering media, the discrete estimator provides smaller errors at proximal source locations while the continuous estimator provides smaller errors at distal locations. The origin of these differing variance characteristics can be understood through examination of the distribution of exiting photon weights. PMID:24562029

  17. Measurement of fission products β decay properties using a total absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Zakari-Issoufou, A.-A.; Porta, A.; Fallot, M.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Agramunt, J.; Äystö, J.; Bowry, M.; Bui, V. M.; Caballero-Folch, R.; Cano-Ott, D.; Eloma, V.; Estévez, E.; Farrelly, G. F.; Garcia, A.; Gelletly, W.; Gomez-Hornillos, M. B.; Gorlychev, V.; Hakala, J.; Jokinen, A.; Jordan, M. D.; Kankainen, A.; Kondev, F. G.; Martinez, T.; Mendoza, E.; Molina, F.; Moore, I.; Perez, A.; Podolyak, Zs.; Penttilä, H.; Regan, P. H.; Rissanen, J.; Rubio, B.; Weber, C.

    2013-12-01

    In a nuclear reactor, the β decay of fission fragments is at the origin of decay heat and antineutrino flux. These quantities are not well known while they are very important for reactor safety and for our understanding of neutrino physics. One reason for the discrepancies observed in the estimation of the decay heat and antineutrinos flux coming from reactors could be linked with the Pandemonium effect. New measurements have been performed at the JYFL facility of Jyväskylä with a Total Absorption Spectrometer (TAS) in order to circumvent this effect. An overview of the TAS technique and first results from the 2009 measurement campaign will be presented.

  18. Change in soft magnetic properties of Fe-based metallic glasses during hydrogen absorption and desorption

    SciTech Connect

    Novak, L.; Lovas, A.; Kiss, L.F.

    2005-08-15

    The stress level can be altered in soft magnetic amorphous alloys by hydrogen absorption. The resulting changes in the soft magnetic parameters are reversible or irreversible, depending on the chemical composition. Some of these effects are demonstrated in Fe-B, Fe-W-B, and Fe-V-B glassy ribbons, in which various magnetic parameters are measured mainly during hydrogen desorption. The rate of hydrogen desorption is also monitored by measuring the pressure change in a hermetically closed bomb. The observed phenomena are interpreted on the basis of induced stresses and chemical interactions between the solute metal and hydrogen.

  19. 'Diamondlike' carbon films - Optical absorption, dielectric properties, and hardness dependence on deposition parameters

    NASA Technical Reports Server (NTRS)

    Natarajan, V.; Lamb, J. D.; Woollam, J. A.; Liu, D. C.; Gulino, D. A.

    1985-01-01

    An RF plasma deposition system was used to prepare amorphous 'diamondlike' carbon films. The source gases for the RF system include methane, ethylene, propane, and propylene, and the parameters varied were power, dc substrate bias, and postdeposition anneal temperature. Films were deposited on various substrates. The main diagnostics were optical absorption in the visible and in the infrared, admittance as a function of frequency, hardness, and Auger and ESCA spectroscopy. Band gap is found to depend strongly on RF power level and band gaps up to 2.7 eV and hardness up to 7 Mohs were found. There appears to be an inverse relationship between hardness and optical band gap.

  20. Calculations of nonlinear response properties using the intermediate state representation and the algebraic-diagrammatic construction polarization propagator approach: two-photon absorption spectra.

    PubMed

    Knippenberg, S; Rehn, D R; Wormit, M; Starcke, J H; Rusakova, I L; Trofimov, A B; Dreuw, A

    2012-02-14

    An earlier proposed approach to molecular response functions based on the intermediate state representation (ISR) of polarization propagator and algebraic-diagrammatic construction (ADC) approximations is for the first time employed for calculations of nonlinear response properties. The two-photon absorption (TPA) spectra are considered. The hierarchy of the first- and second-order ADC∕ISR computational schemes, ADC(1), ADC(2), ADC(2)-x, and ADC(3/2), is tested in applications to H(2)O, HF, and C(2)H(4) (ethylene). The calculated TPA spectra are compared with the results of coupled cluster (CC) models and time-dependent density-functional theory (TDDFT) calculations, using the results of the CC3 model as benchmarks. As a more realistic example, the TPA spectrum of C(8)H(10) (octatetraene) is calculated using the ADC(2)-x and ADC(2) methods. The results are compared with the results of TDDFT method and earlier calculations, as well as to the available experimental data. A prominent feature of octatetraene and other polyene molecules is the existence of low-lying excited states with increased double excitation character. We demonstrate that the two-photon absorption involving such states can be adequately studied using the ADC(2)-x scheme, explicitly accounting for interaction of doubly excited configurations. Observed peaks in the experimental TPA spectrum of octatetraene are assigned based on our calculations.

  1. Comparing optical properties of different species of diatoms

    NASA Astrophysics Data System (ADS)

    Maibohm, C.; Friis, S. M. M.; Su, Y.; Rottwitt, K.

    2015-03-01

    Diatoms are single cellular algae encapsulated in an external wall of micro-structured porous silica called the frustule. Diatoms are present in all water environments and contribute with 20-25 % of the global primary production of oxygen by photosynthesis. The appearance of the frustule is very species dependent with huge variety in size, shape, and microstructure. We have experimentally investigated optical properties of frustules of several species of diatoms to further understand light harvesting properties together with common traits, effects and differences between the different frustules. We have observed, when incident light interacts with the micro-structured frustule it is multiple diffracted giving rise to wavelength dependent multiple focal points and other optical effects. Experimental results have been simulated and well confirmed by free space FFT propagation routine analysis software. The software uses parameters which are extracted from experimental images as basis for simulation and allows us to extract the influence of the different elements of the frustule. The information could be used both for predicting optical properties of diatoms and by changing frustule parameters, maybe by altering growth conditions of the diatoms tailor their optical properties.

  2. Electromagnetic and microwave absorption properties of (Co2+-Si4+) substituted barium hexaferrites and its polymer composite

    NASA Astrophysics Data System (ADS)

    Abbas, S. M.; Chatterjee, R.; Dixit, A. K.; Kumar, A. V. R.; Goel, T. C.

    2007-04-01

    The electromagnetic (EM) and microwave absorption properties of (Co2+-Si4+) substituted barium hexaferrite compositions BaCox2+Fey+2Six+y4+Fe12-2x-2y+3O19 (x =0.9 and y =0.0, 0.05, and 0.2) and its polymer composites prepared from hexaferrite, polyaniline, and carbon powders dispersed in polyurethane matrix have been investigated at the microwave frequency range of the X band (8.2-12.4GHz). The hexaferrite compositions were synthesized by solid-state reaction technique, whereas polyaniline, by chemical route. The permeabilities of a ferrite are drastically reduced at higher gigahertz frequencies. The permittivities, however, can be enhanced by appropriate choice of composition and processing temperature. In the present ferrite composition, silicon content is taken in excess so as to convert some of the Fe3+ ions to Fe2+ ions. This conversion has been shown to enhance EM and absorption properties. Mössbauer spectroscopy on the samples establishes that addition of excess Si4+ converts some of the Fe3+ to Fe2+. The sintered ferrites have shown resonance phenomena, but the composites do not. The EM parameters ɛ', ɛ″, μ', and μ″ were measured using a vector network analyzer (Agilent, model PNA E8364B). These measured EM parameters were used to determine the absorption spectra at different sample thicknesses based on a model of a single layered plane wave absorber backed by a perfect conductor. The sintered ferrite composition (x =0.9 and y =0.05) showed the best absorption properties [a minimum reflection loss of -17.7to-14.3dB over the whole frequency range of the X band (8.2-12.4) for a sample thickness of just 0.8mm], and it is used in the composite absorbers in powder form along with other constituents. The optimized composite absorber has shown dielectric constant ɛ'˜11.5, dielectric loss ɛ″˜2.3, and a minimum reflection loss of -29dB at 10.97GHz with the -20dB bandwidth over the frequency range of 9.7-12.2GHz for a sample thickness of 2.0mm. The

  3. Preparation and radar absorptive properties of BaFe12O19 -coated glass fiber

    NASA Astrophysics Data System (ADS)

    Jia, F.; Xu, M.; Bao, H. Q.; Cui, K.; Zhang, F.

    2016-07-01

    Traditional passive jamming materials such as chaff and foil showed some limitations in use because they can only reflect the electromagnetic wave. Therefore, to develop a kind of absorptive passive jamming material to make up for deficiencies of traditional passive jamming materials and improve the jamming efficiency is of great significance. In this paper, the BaFe12O19-coated glass fiber, used as a kind of radar absorptive chaff, was prepared by sol-gel dip-coating method. The effects of heat treatment temperature, heat treatment time and coating times on film quality, tensile strength and attenuation efficiency of the samples were discussed. The study shows that an increase of the heat treatment temperature and an extension of the heat treatment time is conducive to the growth of barium ferrite grain, while they would introduce the loss of chaff strength at the same time. In addition, multi-coating process can improve the film quality and attenuation efficiency of the sample. Data show that the 10 times coated samples have a best reflectivity of (15GHz, -6.65dB) and the bandwidth of reflectivity lower than -5dB is11.8 GHz. According to the test results, the prepared material has certain attenuation efficiency in the range of 2GHz-18GHz, having a high practical value.

  4. Study on preparation and microwave absorption property of the core-nanoshell composite materials doped with La.

    PubMed

    Wei, Liqiu; Che, Ruxin; Jiang, Yijun; Yu, Bing

    2013-12-01

    Microwave absorbing material plays a great role in electromagnetic pollution controlling, electromagnetic interference shielding and stealth technology, etc. The core-nanoshell composite materials doped with La were prepared by a solid-state reaction method, which is applied to the electromagnetic wave absorption. The core is magnetic fly-ash hollow cenosphere, and the shell is the nanosized ferrite doped with La. The thermal decomposition process of the sample was investigated by thermogravimetry and differential thermal analysis. The morphology and components of the composite materials were investigated by the X-ray diffraction analysis, the microstructure was observed by scanning electron microscope and transmission electron microscope. The results of vibrating sample magnetometer analysis indicated that the exchange-coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating, which caused outstanding magnetic properties. The microwave absorbing property of the sample was measured by reflectivity far field radar cross section of radar microwave absorbing material with vector network analyzer. The results indicated that the exchange-coupling interaction enhanced magnetic loss of composite materials. Therefore, in the frequency of 5 GHz, the reflection coefficient can achieve -24 dB. It is better than single material and is consistent with requirements of the microwave absorbing material at the low-frequency absorption. PMID:25078834

  5. Enhancing and broadening absorption properties of frequency selective surfaces absorbers using FeCoB-based thin film

    NASA Astrophysics Data System (ADS)

    Ren, Wenyi; Nie, Yan; Xiong, Xuan; Zhang, Cui; Zhou, Yan; Gong, Rongzhou

    2012-04-01

    In this paper, the influence of FeCoB-based magnetic film on the absorption properties of traditional frequency selective surface (FSS) was investigated experimentally. A single-layer Minkowski fractal planar frequency selective surface was chosen, and the laser etching technique was proposed to fabricate aluminum-based FSS (AFSS) samples. Magnetic films were prepared by radio frequency magnetron sputtering, with the targets of Fe40Co40B20 and SiO2. It is found that after the magnetic film is incorporated, the bandwidth under -10 dB increases by 33.3% from 5.08 to 6.78 GHz and the peak value of reflectivity decreases from -12.46 to -38.41 dB. The 3.1-mm-thick radar absorber is relatively light and could obtain the reflectivity of -38.41 with -20 dB bandwidth of 1.85 GHz. As a consequence, under the circumstance that the total thickness of the sample maintains relatively constant, the magnetic thin film can effectively improve the absorption properties of the sample.

  6. Study on preparation and microwave absorption property of the core-nanoshell composite materials doped with La.

    PubMed

    Wei, Liqiu; Che, Ruxin; Jiang, Yijun; Yu, Bing

    2013-12-01

    Microwave absorbing material plays a great role in electromagnetic pollution controlling, electromagnetic interference shielding and stealth technology, etc. The core-nanoshell composite materials doped with La were prepared by a solid-state reaction method, which is applied to the electromagnetic wave absorption. The core is magnetic fly-ash hollow cenosphere, and the shell is the nanosized ferrite doped with La. The thermal decomposition process of the sample was investigated by thermogravimetry and differential thermal analysis. The morphology and components of the composite materials were investigated by the X-ray diffraction analysis, the microstructure was observed by scanning electron microscope and transmission electron microscope. The results of vibrating sample magnetometer analysis indicated that the exchange-coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating, which caused outstanding magnetic properties. The microwave absorbing property of the sample was measured by reflectivity far field radar cross section of radar microwave absorbing material with vector network analyzer. The results indicated that the exchange-coupling interaction enhanced magnetic loss of composite materials. Therefore, in the frequency of 5 GHz, the reflection coefficient can achieve -24 dB. It is better than single material and is consistent with requirements of the microwave absorbing material at the low-frequency absorption.

  7. Spectrally Consistent Scattering, Absorption, and Polarization Properties of Atmospheric Ice Crystals at Wavelengths from 0.2 to 100 um

    NASA Technical Reports Server (NTRS)

    Yang, Ping; Bi, Lei; Baum, Bryan A.; Liou, Kuo-Nan; Kattawar, George W.; Mishchenko, Michael I.; Cole, Benjamin

    2013-01-01

    A data library is developed containing the scattering, absorption, and polarization properties of ice particles in the spectral range from 0.2 to 100 microns. The properties are computed based on a combination of the Amsterdam discrete dipole approximation (ADDA), the T-matrix method, and the improved geometric optics method (IGOM). The electromagnetic edge effect is incorporated into the extinction and absorption efficiencies computed from the IGOM. A full set of single-scattering properties is provided by considering three-dimensional random orientations for 11 ice crystal habits: droxtals, prolate spheroids, oblate spheroids, solid and hollow columns, compact aggregates composed of eight solid columns, hexagonal plates, small spatial aggregates composed of 5 plates, large spatial aggregates composed of 10 plates, and solid and hollow bullet rosettes. The maximum dimension of each habit ranges from 2 to 10,000 microns in 189 discrete sizes. For each ice crystal habit, three surface roughness conditions (i.e., smooth, moderately roughened, and severely roughened) are considered to account for the surface texture of large particles in the IGOM applicable domain. The data library contains the extinction efficiency, single-scattering albedo, asymmetry parameter, six independent nonzero elements of the phase matrix (P11, P12, P22, P33, P43, and P44), particle projected area, and particle volume to provide the basic single-scattering properties for remote sensing applications and radiative transfer simulations involving ice clouds. Furthermore, a comparison of satellite observations and theoretical simulations for the polarization characteristics of ice clouds demonstrates that ice cloud optical models assuming severely roughened ice crystals significantly outperform their counterparts assuming smooth ice crystals.

  8. The Synthesis and Characterization of a Group of Transition Metal Octabutoxynaphthalocyanines and the Absorption and Emission Properties of the Co, Rh, Ir, Ni, Pd and Pt Members of This Group.

    PubMed

    Kim, Junhwan; Soldatova, Alexandra V; Rodgers, Michael A J; Kenney, Malcolm E

    2013-07-01

    The synthesis and photophysical properties of new metallo-octabutoxynaphthalocyanines with Rh(III), Ir(III), and Pt(II) are reported. Various metals were inserted into the metal-free octabutoxynaphthalocyanine and the resultant metal complexes were fully characterized by NMR, UV-vis spectroscopy, and mass spectrometry. The absorption and emission properties of these new complexes were also examined and compared to those of Co(II), Ni(II), and Pd(II) octabutoxynaphthalocyanines. The results provide useful information to understand the effect of these transition metals on the properties of this macrocyclic ring. PMID:23745014

  9. The Synthesis and Characterization of a Group of Transition Metal Octabutoxynaphthalocyanines and the Absorption and Emission Properties of the Co, Rh, Ir, Ni, Pd and Pt Members of This Group

    PubMed Central

    Kim, Junhwan; Soldatova, Alexandra V.; Rodgers, Michael A. J.; Kenney, Malcolm E.

    2013-01-01

    The synthesis and photophysical properties of new metallo-octabutoxynaphthalocyanines with Rh(III), Ir(III), and Pt(II) are reported. Various metals were inserted into the metal-free octabutoxynaphthalocyanine and the resultant metal complexes were fully characterized by NMR, UV-vis spectroscopy, and mass spectrometry. The absorption and emission properties of these new complexes were also examined and compared to those of Co(II), Ni(II), and Pd(II) octabutoxynaphthalocyanines. The results provide useful information to understand the effect of these transition metals on the properties of this macrocyclic ring. PMID:23745014

  10. Comparative properties of conventional and alternative fuels. [Standardized data handbook

    SciTech Connect

    Goodger, E.M.

    1983-01-01

    In this handbook Dr. Eric Goodger brings together for the first time standardized data on the characteristic properties of all the major conventional fuels and a wide range of their alternatives. In collating such data and converting them to uniform standards, Dr. Goodger has performed a service to the producers of oil, gas and coal and their alternatives, and all their users. The information previously lay scattered throughout the literature, often requiring long search times to discover, followed by laborious conversion work.

  11. Laboratory evaluation of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1984-01-01

    The microwave absorbing properties of gaseous sulfuric acid (H2SO4) under Venus atmospheric conditions are investigated. The results are applied to measurements from Mariner 5, Mariner 10, and Pioneer/Venus Radio Occultation experiments, to determine abundancies of gaseous sulfuric acid in the Venus atmosphere. The microwave properties of the vapors accompanying liquid H2SO4 are studied to estimate the vapor pressure in an atmospheric model.

  12. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1986-01-01

    The recognition of the need to make laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressure which correspond to the altitudes probed by radio occultation experiments, and over a range of frequencies which correspond to both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. Construction was completed of the outer planets simulator and measurements were conducted of the microwave absorption and refraction from nitrogen under simulated Titan conditions. The results of these and previous laboratory measurements were applied to a wide range of microwave opacity measurements, in order to derive constituent densities and distributions in planetary atmospheres such as Venus.

  13. Scattering and Absorption Properties of Polydisperse Wavelength-sized Particles Covered with Much Smaller Grains

    NASA Technical Reports Server (NTRS)

    Dlugach, Jana M.; Mishchenko, Michael I.; Mackowski, Daniel W.

    2012-01-01

    Using the results of direct, numerically exact computer solutions of the Maxwell equations, we analyze scattering and absorption characteristics of polydisperse compound particles in the form of wavelength-sized spheres covered with a large number of much smaller spherical grains.The results pertain to the complex refractive indices1.55 + i0.0003,1.55 + i0.3, and 3 + i0.1. We show that the optical effects of dusting wavelength-sized hosts by microscopic grains can vary depending on the number and size of the grains as well as on the complex refractive index. Our computations also demonstrate the high efficiency of the new superposition T-matrix code developed for use on distributed memory computer clusters.

  14. THE INTRINSIC FRACTIONS AND RADIO PROPERTIES OF LOW-IONIZATION BROAD ABSORPTION LINE QUASARS

    SciTech Connect

    Dai Xinyu; Shankar, Francesco; Sivakoff, Gregory R.

    2012-10-01

    Low-ionization (Mg II, Fe II, and Fe III) broad absorption line quasars (LoBALs) probe a relatively obscured quasar population and could be at an early evolutionary stage for quasars. We study the intrinsic fractions of LoBALs using the Sloan Digital Sky Survey (SDSS), Two Micron All Sky Survey, and Faint Images of the Radio Sky at Twenty cm survey. We find that the LoBAL fractions of the near-infrared (NIR) and radio samples are approximately 5-7 times higher than those measured in the optical sample. This suggests that the fractions measured in the NIR and radio bands are closer to the intrinsic fractions of the populations, and that the optical fractions are significantly biased due to obscuration effects, similar to high-ionization broad absorption line quasars (HiBALs). Considering a population of obscured quasars that do not enter the SDSS, which could have a much higher LoBAL fraction, we expect that the intrinsic fraction of LoBALs could be even higher. We also find that the LoBAL fractions decrease with increasing radio luminosities, again, similarly to HiBALs. In addition, we find evidence for increasing fractions of LoBALs toward higher NIR luminosities, especially for FeLoBALs with a fraction of {approx}18% at M{sub K{sub s}}< -31 mag. This population of NIR-luminous LoBALs may be at an early evolutionary stage of quasar evolution. To interpret the data, we use a luminosity-dependent model for LoBALs that yields significantly better fits than those from a pure geometric model.

  15. [Properties of Pesudomonas sp. DN-1 in reduction of nitric oxide chelate absorption solution].

    PubMed

    Jing, Guo-hua; Li, Wei; Shi, Yao; Ma, Bi-yao; Tan, Tian-en

    2004-07-01

    Metal chelate absorption is deemed as a promising method of NO removal in FGD system, but the difficulty in the regeneration of the absorption solution hinders its further development. An original method with microbial reduction is proposed in this paper. With the adding of Psudomonas sp. DN-1, which was newly isolated from wastewater treatment plant, FeII (EDTA) NO will be reduced to the environmentally benign gaseous product of N2, and thus FeII (EDTA) was regenerated simultaneously. The effects of the types and amount of carbon source, FeII (EDTA) NO concentration, pH, temperature and the biomass inoculation on bio-reduction efficiency were investigated. The results showed that the microorganism exhibited good performance on bio-reduction of FeII (EDTA) NO with the carbon sources of glucose. 250 mg x L(-1) glucose was enough for microorganism to reduce 6.50 mmol x L(-1) FeII (EDTA) NO completely. The rate of FeII (EDTA) NO reduction did not increase with adding a larger amount of carbon source. The bio-reduction could be achieved efficiently among the temperature range of 40 - 45 degrees C and a pH range of 6.9 - 7.2. The bio-reduction rate increased with the increasing of biomass inoculation. When FeII (EDTA) NO concentration is less than 11.8 mmol x L(-1), the reduction rate increased as the concentration increases, while the concentration is over 11.8 mmol x L(-1), the reduction rate keeps constant. PMID:15515959

  16. Chemical structure and properties of midazolam compared with other benzodiazepines

    PubMed Central

    Gerecke, M.

    1983-01-01

    1 A short review is given of the basic chemical development in the field of `classical' and `annelated' benzodiazepines, distinguishing between pro-drugs and directly acting compounds. 2 Some properties of midazolam that are of special interest for its practical use are discussed, such as: the basicity of its imidazole ring nitrogen, which allows water-soluble salts and well-tolerated aqueous injectable solutions to be prepared; its stability to hydrolytic degradation; its rapid metabolic inactivation, which is mainly determined by the methyl group on the imidazole ring, and which is much faster than that of classical benzodiazepines. PMID:6138062

  17. Electronic properties and absorption spectra of ZnSnP{sub 2} using mBJ potential

    SciTech Connect

    Joshi, Ritu Ahuja, B. L.

    2015-06-24

    We present the energy bands and density of states of ZnSnP{sub 2} using full potential linearized augmented plane wave method with modified Becke Johnson potential. It is found that this compound has a direct band gap of about 2.01 eV at Γ point, which originates from the energy difference between P-3p and Sn-5s states. In addition, we have also calculated absorption spectra in the solar energy range and compared it with that of bulk Si to explore the applicability of ZnSnP{sub 2} in photovoltaic and optoelectronic devices.

  18. Polarization and Thickness Dependent Absorption Properties of Black Phosphorus: New Saturable Absorber for Ultrafast Pulse Generation

    PubMed Central

    Li, Diao; Jussila, Henri; Karvonen, Lasse; Ye, Guojun; Lipsanen, Harri; Chen, Xianhui; Sun, Zhipei

    2015-01-01

    Black phosphorus (BP) has recently been rediscovered as a new and interesting two-dimensional material due to its unique electronic and optical properties. Here, we study the linear and nonlinear optical properties of BP flakes. We observe that both the linear and nonlinear optical properties are anisotropic and can be tuned by the film thickness in BP, completely different from other typical two-dimensional layered materials (e.g., graphene and the most studied transition metal dichalcogenides). We then use the nonlinear optical properties of BP for ultrafast (pulse duration down to ~786 fs in mode-locking) and large-energy (pulse energy up to >18 nJ in Q-switching) pulse generation in fiber lasers at the near-infrared telecommunication band ~1.5 μm. We observe that the output of our BP based pulsed lasers is linearly polarized (with a degree-of-polarization ~98% in mode-locking, >99% in Q-switching, respectively) due to the anisotropic optical property of BP. Our results underscore the relatively large optical nonlinearity of BP with unique polarization and thickness dependence, and its potential for polarized optical pulse generation, paving the way to BP based nonlinear and ultrafast photonic applications (e.g., ultrafast all-optical polarization switches/modulators, frequency converters etc.). PMID:26514090

  19. Polarization and Thickness Dependent Absorption Properties of Black Phosphorus: New Saturable Absorber for Ultrafast Pulse Generation

    NASA Astrophysics Data System (ADS)

    Li, Diao; Jussila, Henri; Karvonen, Lasse; Ye, Guojun; Lipsanen, Harri; Chen, Xianhui; Sun, Zhipei

    2015-10-01

    Black phosphorus (BP) has recently been rediscovered as a new and interesting two-dimensional material due to its unique electronic and optical properties. Here, we study the linear and nonlinear optical properties of BP flakes. We observe that both the linear and nonlinear optical properties are anisotropic and can be tuned by the film thickness in BP, completely different from other typical two-dimensional layered materials (e.g., graphene and the most studied transition metal dichalcogenides). We then use the nonlinear optical properties of BP for ultrafast (pulse duration down to ~786 fs in mode-locking) and large-energy (pulse energy up to >18 nJ in Q-switching) pulse generation in fiber lasers at the near-infrared telecommunication band ~1.5 μm. We observe that the output of our BP based pulsed lasers is linearly polarized (with a degree-of-polarization ~98% in mode-locking, >99% in Q-switching, respectively) due to the anisotropic optical property of BP. Our results underscore the relatively large optical nonlinearity of BP with unique polarization and thickness dependence, and its potential for polarized optical pulse generation, paving the way to BP based nonlinear and ultrafast photonic applications (e.g., ultrafast all-optical polarization switches/modulators, frequency converters etc.).

  20. Comparative Properties of Collaborative Optimization and other Approaches to MDO

    NASA Technical Reports Server (NTRS)

    Alexandrov, Natalia M.; Lewis, Robert Michael

    1999-01-01

    We discuss criteria by which one can classify, analyze, and evaluate approaches to solving multidisciplinary design optimization (MDO) problems. Central to our discussion is the often overlooked distinction between questions of formulating MDO problems and solving the resulting computational problem. We illustrate our general remarks by comparing several approaches to MDO that have been proposed.

  1. Comparative Properties of Collaborative Optimization and Other Approaches to MDO

    NASA Technical Reports Server (NTRS)

    Alexandrov, Natalia M.; Lewis, Robert Michael

    1999-01-01

    We, discuss criteria by which one can classify, analyze, and evaluate approaches to solving multidisciplinary design optimization (MDO) problems. Central to our discussion is the often overlooked distinction between questions of formulating MDO problems and solving the resulting computational problem. We illustrate our general remarks by comparing several approaches to MDO that have been proposed.

  2. In vivo multispectral imaging of the absorption and scattering properties of exposed brain using a digital red-green-blue camera

    NASA Astrophysics Data System (ADS)

    Yoshida, Keiichiro; Ishizuka, Tomohiro; Mizushima, Chiharu; Nishidate, Izumi; Kawauchi, Satoko; Sato, Shunichi; Sato, Manabu

    2015-04-01

    To evaluate multi-spectral images of the absorption and scattering properties in the cerebral cortex of rat brain, we investigated spectral reflectance images estimated by the Wiener estimation method using a digital red-green-blue camera. A Monte Carlo simulation-based multiple regression analysis for the corresponding spectral absorbance images at nine wavelengths (500, 520, 540, 560, 570, 580, 600, 730, and 760 nm) was then used to specify the absorption and scattering parameters. The spectral images of absorption and reduced scattering coefficients were reconstructed from the absorption and scattering parameters. We performed in vivo experiments on exposed rat brain to confirm the feasibility of this method. The estimated images of the absorption coefficients were dominated by hemoglobin spectra. The estimated images of the reduced scattering coefficients had a broad scattering spectrum, exhibiting a larger magnitude at shorter wavelengths, corresponding to the typical spectrum of brain tissue published in the literature.

  3. Photochromic polymers as a versatile tool for devices based on switchable absorption and other optical properties

    NASA Astrophysics Data System (ADS)

    Bertarelli, Chiara; Castagna, Rossella; Pariani, Giorgio; Bianco, Andrea

    2011-10-01

    Photochromic polymer materials with large modulation of properties enable the production of functional optical devices. The light-triggered change in color has been exploited to develop multi-object focal plane masks for astronomical instrumentation and holographic optical elements for interferometric optical testing. Modulation of properties other than color (i.e. refractive index, light emission or Raman scattering) opens the way to many other applications into technology, such as rewritable optical memories, switchable organic lasers, etc. In this background, examples from molecular design to devices are highlighted.

  4. Comparing the effects of sucrose and glucose on functional properties of pregelatinized maize starch.

    PubMed

    Hedayati, Sara; Shahidi, Fakhri; Koocheki, Arash; Farahnaky, Asgar; Majzoobi, Mahsa

    2016-07-01

    Pregelatinized (PG) starches are extensively used in food products which are processed at low temperature, to increase viscosity and offer a desirable texture. The functional properties of PG starch can be influenced by other constituents used in food matrices. Therefore the main purpose of this study was to investigate the effects of different levels of sucrose and glucose (0, 10, 20, 30 and 40% of dry starch weight basis) as two common sweeteners on drum dried pregelatinized maize starch. Samples were characterized by light microscopy, water absorption, syneresis, cold paste viscosity, texture and turbidity measurements. The results indicated that the amount of leached glucose chains to the aqueous phase, water absorption, viscosity and mechanical properties increased when increasing the sugar concentration while, syneresis and turbidity decreased. However, these effects were more obvious in samples containing sucrose than those with glucose.

  5. Comparing the effects of sucrose and glucose on functional properties of pregelatinized maize starch.

    PubMed

    Hedayati, Sara; Shahidi, Fakhri; Koocheki, Arash; Farahnaky, Asgar; Majzoobi, Mahsa

    2016-07-01

    Pregelatinized (PG) starches are extensively used in food products which are processed at low temperature, to increase viscosity and offer a desirable texture. The functional properties of PG starch can be influenced by other constituents used in food matrices. Therefore the main purpose of this study was to investigate the effects of different levels of sucrose and glucose (0, 10, 20, 30 and 40% of dry starch weight basis) as two common sweeteners on drum dried pregelatinized maize starch. Samples were characterized by light microscopy, water absorption, syneresis, cold paste viscosity, texture and turbidity measurements. The results indicated that the amount of leached glucose chains to the aqueous phase, water absorption, viscosity and mechanical properties increased when increasing the sugar concentration while, syneresis and turbidity decreased. However, these effects were more obvious in samples containing sucrose than those with glucose. PMID:27083847

  6. Absorption Properties of Mediterranean Aerosols Obtained from Multi-year Ground-based and Satellite Remote Sensing Observations

    NASA Technical Reports Server (NTRS)

    Mallet, M.; Dubovik, O.; Nabat, P.; Dulac, F.; Kahn, R.; Sciare, J.; Paronis, D.; Leon, J. F.

    2013-01-01

    Aerosol absorption properties are of high importance to assess aerosol impact on regional climate. This study presents an analysis of aerosol absorption products obtained over the Mediterranean Basin or land stations in the region from multi-year ground-based AERONET and satellite observations with a focus on the Absorbing Aerosol Optical Depth (AAOD), Single Scattering Albedo (SSA) and their spectral dependence. The AAOD and Absorption Angstrom Exponent (AAE) data set is composed of daily averaged AERONET level 2 data from a total of 22 Mediterranean stations having long time series, mainly under the influence of urban-industrial aerosols and/or soil dust. This data set covers the 17 yr period 1996-2012 with most data being from 2003-2011 (approximately 89 percent of level-2 AAOD data). Since AERONET level-2 absorption products require a high aerosol load (AOD at 440 nm greater than 0.4), which is most often related to the presence of desert dust, we also consider level-1.5 SSA data, despite their higher uncertainty, and filter out data with an Angstrom exponent less than 1.0 in order to study absorption by carbonaceous aerosols. The SSA data set includes both AERONET level-2 and satellite level-3 products. Satellite-derived SSA data considered are monthly level 3 products mapped at the regional scale for the spring and summer seasons that exhibit the largest aerosol loads. The satellite SSA dataset includes the following products: (i) Multi-angle Imaging SpectroRadiometer (MISR) over 2000-2011, (ii) Ozone Monitoring Instrument (OMI) near-UV algorithm over 2004-2010, and (iii) MODerate resolution Imaging Spectroradiometer (MODIS) Deep-Blue algorithm over 2005-2011, derived only over land in dusty conditions. Sun-photometer observations show that values of AAOD at 440 nm vary between 0.024 +/- 0.01 (resp. 0.040 +/- 0.01) and 0.050 +/- 0.01 (0.055 +/- 0.01) for urban (dusty) sites. Analysis shows that the Mediterranean urban-industrial aerosols appear "moderately

  7. A physico-chemical properties based model for estimating evaporation and absorption rates of perfumes from skin.

    PubMed

    Kasting, G B; Saiyasombati, P

    2001-02-01

    Because of their potential for inducing allergic contact dermatitis (ACD) if used improperly, perfumes are carefully assessed for dermal safety prior to incorporation into cosmetic products. Exposure assessment for these materials often involves the conservative assumption of 100% absorption of each component. This report describes an improved method to estimate the absorption and evaporation of perfume ingredients from skin, based on their physico-chemical properties. The effect of environmental variables such as temperature and wind velocity can be accounted for in a logical way. This was accomplished using a first-order kinetic approach expected to be applicable for small doses applied to skin. Skin penetration rate was calculated as a fraction of the maximum flux estimated from the compound's lipid solubility, S(lip) (represented by the product of octanol/water partition coefficient, K(octt), and water solubility, S(w)), and molecular weight, MW. Evaporation rates were estimated from a modified Henry's Law approach with a stagnant boundary layer whose thickness is a function of surface airflow, v. At a given value of v, evaporation rate was assumed proportional to the ratio P(vp)/S(lip), where P(vp) is the vapour pressure of the ingredient at skin temperature, T. The model predicts a relationship for total evaporation from skin of the form %evap = 100x/(k+x) where x = P(vp)MW(2.7)/(K(oct)S(w)) and k is a parameter which depends only on v and T. Comparison with published data on perfume evaporation from human skin in vivo showed good agreement between theory and experiment for two closely related perfume mixtures (r(2) = 0.52-0.74, s = 12-14%, n = 10). Thus, the method would seem to have a good prospect of providing skin absorption estimates suitable for use in exposure assessment and improved understanding of dose-related contact allergy.

  8. Morphology, absorptivity and viscoelastic properties of mineralized PVP-CMC hydrogel

    NASA Astrophysics Data System (ADS)

    Saha, Nabanita; Shah, Rushita; Vyroubal, Radek; Kitano, Takeshi; Saha, Petr

    2013-04-01

    A simple liquid diffusion mineralization technique was applied for the incorporation of calcium carbonate (CaCO3) in PVP-CMC hydrogel. The hydrogel was prepared 6.5 mm thick to achieve around 1 mm thick sample after mineralization of hydrogel matrix with calcite. The calcite crystals were round shaped and organized as building blocks inside the porous three dimensional cross linked structure of the PVP-CMC hydrogel. The present study was designed to evaluate the properties of mineralized (calcite) hydrogel with respect to freshly prepared hydrogel and those swelled in water (H2O) after drying. The viscoelastic properties of swelled and mineralized samples were reported though the dry PVP-CMC hydrogel were swelled and mineralized with calcite until 150 min. It is observed that there is not much difference in elastic property of fresh and 60 min mineralized hydrogels but the values of elastic property are decreased in the case of swelled hydrogels. It is interesting that in case of swelled samples the values of complex viscosity (η*) are increased with the increase of swelling time after 90 min but in case of calcite hydrogel the values (η*) are gradually decreased with the increase of time.

  9. Optoelectronic properties of Mg{sub 2}Si semiconducting layers with high absorption coefficients

    SciTech Connect

    Kato, Takashi; Sago, Yuichiro; Fujiwara, Hiroyuki

    2011-09-15

    In an attempt to develop a low-cost material for solar cell devices, polycrystalline magnesium silicide (poly-Mg{sub 2}Si) semiconducting layers have been prepared by applying rf magnetron sputtering using a Mg{sub 2}Si target. The optimum substrate temperature for the poly-Mg{sub 2}Si growth was found to be T{sub s} = 200 deg. C; the film deposition at higher temperatures leads to desorption of Mg atoms from the growing surface, while the amorphous phase formation occurs at room temperature. The poly-Mg{sub 2}Si layer deposited at T{sub s} = 200 deg. C shows the (111) preferential orientation with a uniform grain size of {approx}50 nm. The dielectric function of the poly-Mg{sub 2}Si layer has been determined accurately by spectroscopic ellipsometry. From the analysis, quite high absorption coefficients and an indirect gap of 0.77 eV in the poly-Mg{sub 2}Si layer have been confirmed. The above poly-Mg{sub 2}Si layer shows clear photoconductivity and can be applied as a narrow-gap bottom layer in multi-junction solar cell devices.

  10. Studies on the synthesis and microwave absorption properties of Fe3 O4/polyaniline FGM

    NASA Astrophysics Data System (ADS)

    Han, Xiao; Wang, Yuan-Sheng

    2007-12-01

    Electrically conducting polyaniline (PANI)-magnetic oxide (Fe3 O4) composites were synthesized by emulsion polymerization in the presence of dodecyl benzene sulfonic acid (DBSA) as the surfactant and dopant and ammonium persulfate (APS) as the oxidant. Transmission electron microscopy (TEM) indicates that the composite has a magnetic core and an electric shell and the modification has prevented the aggregation of Fe3 O4 nanoparticles effectively. The electromagnetic parameter measurements (ɛ'', ɛ', μ'' and μ') in the range of 2-18 GHz prove that Fe3 O4 in the Fe3 O4/PANI/DBSA is responsible for the electric and ferromagnetic behavior of the composites. As a result, the electromagnetic parameters can be designed by adjusting the content of the Fe3 O4. The microwave absorption of functionally graded material (FGM) was simulated by the computer according to the principle of impedance match and the calculated results agreed quite well with the experimentally measured data (R<-20 dB, Δf>4 GHz).

  11. Comparison of isorhamnetin absorption properties in total flavones of Hippophae rhamnoides L. with its pure form in a Caco-2 cell model mediated by multidrug resistance-associated protein.

    PubMed

    Xie, Yan; Duan, Jingze; Fu, Qingxue; Xia, Mengxin; Zhang, Lei; Li, Guowen; Wu, Tao; Ji, Guang

    2015-06-20

    Total flavones of Hippophae rhamnoides L. (TFH) are extracted from the widely distributed thorny bush Sea buckthorn (Hippophae rhamnoides L.). Isorhamnetin (IS) is one of the representative ingredients in TFH. In this study, the absorption properties of IS in TFH and its pure form were compared through transepithelial transport and cellular uptake experiments in a Caco-2 cell model. Our results show that the absorption properties of IS in TFH and its pure form were remarkably different: (1) Both PappAB and PappBA of IS in TFH were dramatically increased compared with those of IS pure form; consequently, its Pratio was 2.3-fold higher than that of IS; (2) Both the accumulation and efflux of IS in TFH were significantly enhanced compared with the single compound. One likely reason for these differences is that the multiple components in TFH significantly down regulated the mRNA expression level of MRP2, which lead to a decrease in the protein level of MRP2, based on western blotting and RT-PCR assays. This study highlights the significant differences in the absorption properties of flavonoid components in different forms and the potential multi-component interactions in TFH. PMID:25813735

  12. Correlating Fluorescence and Absorption Properties of Dissolved Organic Matter in Northern Peatland Soil Porewaters with Molecular Composition Information

    NASA Astrophysics Data System (ADS)

    Tfaily, M. M.; D'Andrilli, J.; Corbett, J.; Chanton, J.; Cooper, W. T.

    2009-12-01

    Northern peatlands store roughly half as much carbon as is stored as CO2 in the atmosphere in the form of complex biogeopolymers. As climate change proceeds, increasing carbon release from these historically carbon-sequestering environments may represent an unidentified forcing stress on global temperatures. In this work, we have applied absorption spectroscopy, Excitation/Emission Matrix (EEM) spectroscopy and ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) to study the differences in composition of dissolved organic matter (DOM) in soil porewaters at varying depths from different sites (fens and bogs) within the Glacial Lake Agassiz Peatlands (GLAP) of northern Minnesota. UV/Vis absorbance and Excitation Emission Matrix Fluorescence Spectroscopy (EEMS) were used to identify changes in the optical properties associated with the chromophoric fractions of DOM (CDOM). Higher specific UV absorbance (SUVA) at 254 nm indicated relatively more aromatic content in the DOM in surface bog and deep fen horizons. EEMS results were also found to be in agreement with the absorption spectra and molecular characterization as determined by FT-ICR-MS. The strong correlations we have observed suggest that optical spectroscopy techniques represent an effective surrogate approach to characterizing the composition of DOM provided some detailed molecular information is available for calibrating the observed correlations.

  13. Optical and structural properties of plasma-treated Cordyceps bassiana spores as studied by circular dichroism, absorption, and fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Geon Joon; Sim, Geon Bo; Choi, Eun Ha; Kwon, Young-Wan; Kim, Jun Young; Jang, Siun; Kim, Seong Hwan

    2015-01-01

    To understand the killing mechanism of fungal spores by plasma treatment, the optical, structural, and biological properties of the insect pathogenic fungus Cordyceps bassiana spores were studied. A nonthermal atmospheric-pressure plasma jet (APPJ) was used to treat the spores in aqueous solution. Optical emission spectra of the APPJ acquired in air indicated emission peaks corresponding to hydroxyl radicals and atomic oxygen. When the APPJ entered the aqueous solution, additional reactive species were derived from the interaction of plasma radicals with the aqueous solution. Fluorescence and absorption spectroscopy confirmed the generation of hydroxyl radicals and hydrogen peroxide in the plasma-activated water (PAW). Spore counting showed that plasma treatment significantly reduced spore viability. Absorption spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis of the DNA extracted from plasma-treated spores showed a reduction in spore DNA content. The magnitude of the dip in the CD spectrum was lower in the plasma-treated spores than in the control, indicating that plasma treatment causes structural modifications and/or damage to cellular components. Tryptophan fluorescence intensity was lower in the plasma-treated spores than in the control, suggesting that plasma treatment modified cell wall proteins. Changes in spore viability and DNA content were attributed to structural modification of the cell wall by reactive species coming from the APPJ and the PAW. Our results provided evidence that the plasma radicals and the derived reactive species play critical roles in fungal spore inactivation.

  14. Optical and structural properties of plasma-treated Cordyceps bassiana spores as studied by circular dichroism, absorption, and fluorescence spectroscopy

    SciTech Connect

    Lee, Geon Joon Sim, Geon Bo; Choi, Eun Ha; Kim, Jun Young; Jang, Siun; Kim, Seong Hwan

    2015-01-14

    To understand the killing mechanism of fungal spores by plasma treatment, the optical, structural, and biological properties of the insect pathogenic fungus Cordyceps bassiana spores were studied. A nonthermal atmospheric-pressure plasma jet (APPJ) was used to treat the spores in aqueous solution. Optical emission spectra of the APPJ acquired in air indicated emission peaks corresponding to hydroxyl radicals and atomic oxygen. When the APPJ entered the aqueous solution, additional reactive species were derived from the interaction of plasma radicals with the aqueous solution. Fluorescence and absorption spectroscopy confirmed the generation of hydroxyl radicals and hydrogen peroxide in the plasma-activated water (PAW). Spore counting showed that plasma treatment significantly reduced spore viability. Absorption spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis of the DNA extracted from plasma-treated spores showed a reduction in spore DNA content. The magnitude of the dip in the CD spectrum was lower in the plasma-treated spores than in the control, indicating that plasma treatment causes structural modifications and/or damage to cellular components. Tryptophan fluorescence intensity was lower in the plasma-treated spores than in the control, suggesting that plasma treatment modified cell wall proteins. Changes in spore viability and DNA content were attributed to structural modification of the cell wall by reactive species coming from the APPJ and the PAW. Our results provided evidence that the plasma radicals and the derived reactive species play critical roles in fungal spore inactivation.

  15. Properties of solid dispersions of selected magnesium salts and the absorption process of Mg2+ ions in vitro

    NASA Astrophysics Data System (ADS)

    Marcoin, Waclawa; Duda, Henryk; Chrobak, Dariusz

    2011-01-01

    The paper presents an application of phosphatidylcholine 45% (PC 45) and polyvinylpyrrolidone (PVP) in formulations of magnesium salts such as Mg(VitB6) and Mg(VitB6Arg) prepared by solid dispersion (SD) techniques. The evaluation of influence of the selected carriers on some physicochemical properties of solid dispersions and on the absorption process of Mg +2 ions in vitro were made. An infrared (IR) spectra study suggested creation of a hydrogen bond between the carriers and the examined magnesium salts. The results of the following thermal analysis: differential thermal analysis (DTA), thermogravimetry (TG), and differential scanning calorimetry (DSC) showed that application of PVP into SD lower the temperature of the decomposition process. However, in the case of PC 45 into SD the characteristic thermal effects of higher temperatures were observed. Moreover, values of the enthalpy SD of decomposition process were decreased. The results of these studies on absorption process of Mg2+ ions in vitro showed the positive influence of the applied carriers on the partition coefficient values (log P) in the examined formulation.

  16. Preparation and electromagnetic wave absorption properties of Sm2O3/α-Fe/Sm2Fe17Nx composites

    NASA Astrophysics Data System (ADS)

    Ye, Jinwen; Liu, Ying; Zhang, Jiao; Chen, Xianfu; Yao, Mingying

    2013-06-01

    Sm2O3/α-Fe/Sm2Fe17Nx composites were prepared in situ by hydrogenation-disproportionation-oxygen-desorption-recombination and nitrogen process, and their electromagnetic wave absorption properties were measured in the frequency range of 0.5-18 GHz. The result showed that saturation magnetization and coercivity of as-prepared powder with 25.3 wt% Sm2O3, 64.4 wt% α-Fe and 10.3 wt% Sm2Fe17N3 were 134.57 emu/g and 654.5 G, respectively. The dielectric constant of composites was low over the frequency range of 0.5-18 GHz, and their resonance frequencies were at a high frequency range. The resin composite of Sm2O3/α-Fe/Sm2Fe17N3 exhibited effective electromagnetic wave absorption (RL≤20 dB) in a frequency range 3-9 GHz, for absorber thickness ranging from 3 to 8 mm, respectively. A minimum reflection loss of -53 dB from the samples was observed at 7 GHz with an absorber thickness of 3.59 mm.

  17. Comparative study of viscoelastic properties using virgin yogurt

    SciTech Connect

    Dimonte, G.; Nelson, D.; Weaver, S.; Schneider, M.; Flower-Maudlin, E.; Gore, R.; Baumgardner, J.R.; Sahota, M.S.

    1998-07-01

    We describe six different tests used to obtain a consistent set of viscoelastic properties for yogurt. Prior to yield, the shear modulus {mu} and viscosity {eta} are measured nondestructively using the speed and damping of elastic waves. Although new to foodstuffs, this technique has been applied to diverse materials from metals to the earth{close_quote}s crust. The resultant shear modulus agrees with {mu}{approximately}E/3 for incompressible materials, where the Young{close_quote}s modulus E is obtained from a stress{endash}strain curve in compression. The tensile yield stress {tau}{sub o} is measured in compression and tension, with good agreement. The conventional vane and cone/plate rheometers measured a shear stress yield {tau}{sub os}{approximately}{tau}{sub o}/{radical} (3) , as expected theoretically, but the inferred {open_quotes}apparent{close_quotes} viscosity from the cone/plate rheometer is much larger than the wave measurement due to the finite yield ({tau}{sub os}{ne}0). Finally, we inverted an open container of yogurt for 10{sup 6} s{gt}{eta}/{mu} and observed no motion. This demonstrates unequivocally that yogurt possesses a finite yield stress rather than a large viscosity. We present a constitutive model with a pre-yield viscosity to describe the damping of the elastic waves and use a simulation code to describe yielding in complex geometry. {copyright} {ital 1998 Society of Rheology.}

  18. A comparative evaluation of mechanical properties of nanofibrous materials

    NASA Astrophysics Data System (ADS)

    Lyubun, German P.; Bessudnova, Nadezda O.

    2014-01-01

    Restoration or replacement of lost or damaged hard tooth tissues remain a reconstructive clinical dentistry challenge. One of the most promising solutions to this problem is the development of novel concepts and methodologies of tissue engineering for the synthesis of three-dimensional graft constructs that are equivalent to original organs and tissues. This structural and functional compatibility can be reached by producing ultra-thin polymer filament scaffolds. This research aims through a series of studies to examine different methods of polymer filament material special preparation and test mechanical properties of the produced materials subjected to a tensile strain. Nanofibrous material preparation using chemically pure acetone and mixtures of ethanol/water has shown no significant changes in sample surface morphology. The high temperature impact on material morphology has resulted in the modification of fiber structure. In the course of mechanical tests it has been revealed the dependence of the material strength on the spinning solution compositions. The results achieved point to the possibility to develop nanofibrous materials with required parameters changing the methodology of spinning solution production.

  19. Influence of resin system on the energy absorption capability and morphological properties of plain woven kenaf composites

    NASA Astrophysics Data System (ADS)

    Salman, S. D.; Leman, Z.; Sultan, M. T. H.; Ishak, M. R.; Cardona, F.

    2015-12-01

    Due to both environmental and technical advantages, natural fibers are being used as reinforcement of polymeric composite in many industries. The flexibility of the most natural fibers is one of the important technical characteristic which allows them to resist impact forces. An investigation was carried out to compare the energy absorption capability of kenaf/PVB film and kenaf/epoxy composites. The hot and cold press techniques were used to fabricate the specimens with 35% kenaf fibre weight fraction. The charpy impact test was performed on forty notched specimens using a pendulum impact tester with different hammer energy. The results showed that the kenaf/PVB film composite has the highest energy absorption, strength and toughness compared with the epoxy composite. At high energy levels, the impact strength and toughness of the kenaf/PVB film was six times of kenaf/epoxy composite. In addition, the scanning electron microscopy was assessed to demonstrate the different failure in fracture surfaces. It was found that the kenaf/PVB film composite failed by fibre fracture while kenaf/epoxy composite failed by a combination of fibre pull-out and fibre fracture as well as crack propagations through the matrix.

  20. New insights into two-photon absorption properties of functionalized aza-BODIPY dyes at telecommunication wavelengths: a theoretical study.

    PubMed

    Liu, Xiaoting; Zhang, Jilong; Li, Kai; Sun, Xiaobo; Wu, Zhijian; Ren, Aimin; Feng, Jikang

    2013-04-01

    Special attention has been paid to understanding the structural effect on electronic structure and absorption spectra for an extensive series of functionalized aza-BODIPY molecules. We have employed the quadratic response theory as well as a sum-over-states approach involving few intermediate states to calculate the two-photon cross section (δmax). The results suggest that chemical modifications on the aza-BODIPY core and peripheral moieties using various substituents can finely tune their linear and nonlinear optical properties. Therefore, some new fluorophores absorbing in the near infrared region and featuring considerably high δmax at telecommunication wavelengths are proposed, which are excellent candidates for nonlinear transmission and fluorescent labeling materials. The investigation contributes a useful starting point for further design of more effective aza-BODIPY dyes and can be valuable as a foundation for future experimental research and development.

  1. Reversible modulation of electric transport properties by oxygen absorption and releasing on Nb:SrTiO{sub 3} surface

    SciTech Connect

    Lu, H. X.; Liu, Y. B.; Chen, Y. S. Wang, J.; Shen, B. G.; Sun, J. R.

    2014-11-07

    Pt Schottky contacts on (001)-orientated Nb-doped SrTiO{sub 3} (NSTO) in both ambient air and vacuum were investigated by the conductive atomic force microscope. The co-existed TiO{sub 2} and SrO termination layers were identified on the terrace-structured NSTO surface, where the former possessed a higher forward current than the latter. In ambient air, the barrier height of Pt/NSTO Schottky junction exhibited periodical variation with cyclic terrace plane and step sites, whereas it became homogeneous in ambient vacuum. We suggested that the oxygen absorption and releasing of surface dangling bonds were the origin for reversible changes in transport properties, which indicates a feasible approach for the surface modulation and band structure tailoring of NSTO based heterojunctions.

  2. Ferrocene-Substituted Naphthalenediimide with Broad Absorption and Electron-Transport Properties in the Segregated-Stack Structure.

    PubMed

    Takai, Atsuro; Sakamaki, Daisuke; Seki, Shu; Matsushita, Yoshitaka; Takeuchi, Masayuki

    2016-05-23

    A new naphthalenediimide (NDI) molecule, where two ferrocene (Fc) units were directly attached to both imide nitrogens (Fc-NDI-Fc), was synthesized. The Fc units provide high crystallinity to Fc-NDI-Fc with good solubility to conventional organic solvents. The Fc units also work as electron-donating substituents, in contrast to the electron-deficient NDI unit, resulting in broad charge-transfer absorption of Fc-NDI-Fc from the UV region to 1500 nm in the solid state. The crystal structure analysis revealed that Fc-NDI-Fc formed a segregated-stack structure. The DFT calculation based on the crystal structure showed that the NDI π-orbitals extended over two axes. The extended π-network of the NDI units led to the electron-transport properties of Fc-NDI-Fc, which was confirmed using a flash-photolysis time-resolved microwave conductivity technique. PMID:27061109

  3. Temperature dependence of the electromagnetic properties and microwave absorption of carbonyl iron particles/silicone resin composites

    NASA Astrophysics Data System (ADS)

    Zhou, Yingying; Zhou, Wancheng; Qing, Yuchang; Luo, Fa; Zhu, Dongmei

    2015-01-01

    Microwave absorbing composites with thin thickness and wideband absorption were successfully prepared by a spraying method using carbonyl iron particles (CIPs) as absorbers and silicone resin as the matrix. The value of reflection loss (RL) below -5 dB can be obtained in the frequency range of 5.76-18 GHz for the composite with 0.8 mm thickness. The temperature dependence of electromagnetic properties and RL of the composites were investigated. The RL of the composite showed a slight variation when the temperature reached up to 200 °C while decreased at 300 °C. The room temperature RL of the composite did not display significant difference before and after the heat treatment at 300 °C for 10 h; the mechanism was also discussed.

  4. Magnetic and microwave absorption properties of self-assemblies composed of core-shell cobalt-cobalt oxide nanocrystals.

    PubMed

    Wang, Zhongzhu; Bi, Hong; Wang, Peihong; Wang, Min; Liu, Zhiwei; Shen, Lei; Liu, Xiansong

    2015-02-01

    Core-shell structure cobalt-cobalt oxide nanocomposites were directly synthesized via annealing Co nanocrystals in air at 300 °C. Their microstructure and magnetic properties were characterized by XRD, TEM, XPS and VSM, respectively. The microwave absorbing properties of the nanocomposite powders by dispersing them in wax were investigated in the 2-18 GHz frequency range. The sample that was annealed for 1 h exhibits the maximum reflection loss of -30.5 dB and a bandwidth of less than -10 dB covering the 12.6-17.3 GHz range with the coating thickness of only 1.7 mm. At the same thickness, the sample annealed for 3 h exhibits the maximum reflection loss of -24 dB and a bandwidth that almost covers the whole X-band (8-11.5 GHz). With increase in the insulating cobalt oxide shell, the enhanced permeability could contribute to the decrease of eddy current loss, and the permittivity could be easily adjusted; thus, the microwave absorption properties of the cobalt oxide nanocrystals could be easily adjusted. PMID:25559407

  5. Effect of sand and moisture on molten salt properties for open direct absorption solar receiver/storage system

    NASA Astrophysics Data System (ADS)

    AlQaydi, M. S.; Delclos, T.; AlMheiri, S.; McKrell, T.; Calvet, N.

    2016-05-01

    Solar Salt (60 wt. % sodium nitrate, 40 wt. % potassium nitrate) is one candidate salt mixture for the CSPonD Demo project (Concentrated Solar Power On Demand Demonstration), ongoing collaboration between Masdar Institute and MIT. One prototype is under preparation at the Masdar Institute Solar Platform in Abu Dhabi. In this new concept, the salt will be used as an open direct absorption solar receiver integrated with a storage system so that the effects of dust/sand and moisture on the thermophysical properties have to be investigated. Thermal Gravimetric Analysis (TGA) was used to study the thermal stability and mass loss, while a Differential Scanning Calorimeter (DSC) was used to study the thermal properties and heat capacity of the salt mixture with and without sand. Considering the worst case scenario, the maximum mass loss rate at 550 °C, and in a fully open configuration, was measured to be 0.29 % per hour, around 2.34 per day of use (8 h of operation). The effect of sand was the same under nitrogen gas environment and air with moisture, which resulted in decreasing the melting temperature of the salts mixture and increasing its freezing temperature. The thermal properties remained stable even after 3 temperature cycles with impurities. Finally, the salt heat capacity increased due to the addition of 2 wt. % of sand.

  6. Comparative analysis of physicochemical properties of root perforation sealer materials

    PubMed Central

    Dorileo, Maura Cristiane Gonçales Orçati; Pedro, Fábio Luis Miranda; Bandeca, Matheus Coelho; Guedes, Orlando Aguirre; Villa, Ricardo Dalla

    2014-01-01

    Objectives This study evaluated the solubility, dimensional alteration, pH, electrical conductivity, and radiopacity of root perforation sealer materials. Materials and Methods For the pH test, the samples were immersed in distilled water for different periods of time. Then, the samples were retained in plastic recipients, and the electrical conductivity of the solution was measured. The solubility, dimensional alteration, and radiopacity properties were evaluated according to Specification No. 57 of the American National Standards Institute/American Dental Association (ANSI/ADA). Statistical analyses were carried out using analysis of variance (ANOVA) and Tukey's test at a significance level of 5%. When the sample distribution was not normal, a nonparametric ANOVA was performed with a Kruskal-Wallis test (α = 0.05). Results The results showed that white structural Portland cement (PC) had the highest solubility, while mineral trioxide aggregate (MTA)-based cements, ProRoot MTA (Dentsply-Tulsa Dental) and MTA BIO (Ângelus Ind. Prod.), had the lowest values. MTA BIO showed the lowest dimensional alteration values and white PC presented the highest values. No differences among the tested materials were observed in the the pH and electrical conductivity analyses. Only the MTA-based cements met the ANSI/ADA recommendations regarding radiopacity, overcoming the three steps of the aluminum step wedge. Conclusions On the basis of these results, we concluded that the values of solubility and dimensional alteration of the materials were in accordance with the ANSI/ADA specifications. PCs did not fulfill the ANSI/ADA requirements regarding radiopacity. No differences were observed among the materials with respect to the pH and electrical conductivity analyses. PMID:25110644

  7. [Comparative carcinogenic properties of basalt fiber and chrysotile-asbestos].

    PubMed

    Nikitina, O V; Kogan, F M; Vanchugova, N N; Frash, V N

    1989-01-01

    In order to eliminate asbestos adverse effect on workers' health it was necessary to use mineral rayon, primarily basalt fibre, instead of asbestos. During a chronic experiment on animals the oncogenicity of 2 kinds of basalt fibre was studied compared to chrysotile asbestos. The dust dose of 25 mg was twice administered by intraperitonial route. All types of dust induced the onset of intraperitonial mesotheliomas but neoplasm rates were significantly lower in the groups exposed to basalt fibre. There was no credible data on the differences between the groups exposed to various types of basalt fibre. Since the latter produced some oncogenic effect, it was necessary to develop a complex of antidust measures, fully corresponding to the measures adopted for carcinogenic dusts.

  8. Geometric properties and comparative biomechanics of Homo floresiensis mandibles.

    PubMed

    Daegling, David J; Patel, Biren A; Jungers, William L

    2014-03-01

    The hypodigm of Homo floresiensis from the cave of Liang Bua on Flores Island in the archipelago of Indonesia includes two mandibles (LB1/2 and LB6/1). The morphology of their symphyses and corpora has been described as sharing similarities with both australopiths and early Homo despite their Late Pleistocene age. Although detailed morphological comparisons of these mandibles with those of modern and fossil hominin taxa have been made, a functional analysis in the context of masticatory biomechanics has yet to be performed. Utilizing data on cortical bone geometry from computed tomography scans, we compare the mechanical attributes of the LB1 and LB6 mandibles with samples of modern Homo, Pan, Pongo, and Gorilla, as well as fossil samples of Paranthropus robustus, Australopithecus africanus and South African early Homo. Structural stiffness measures were derived from the geometric data to provide relative measures of mandibular corpus strength under hypothesized masticatory loading regimes. These mechanical variables were evaluated relative to bone area, mandibular length and estimates of body size to assess their functional affinities and to test the hypothesis that the Liang Bua mandibles can be described as scaled-down variants of either early hominins or modern humans. Relative to modern hominoids, the H. floresiensis material appears to be relatively strong in terms of rigidity in torsion and transverse bending, but is relatively weak under parasagittal bending. Thus, they are 'robust' relative to modern humans (and comparable with australopiths) under some loads but not others. Neither LB1 nor LB6 can be described simply as 'miniaturized' versions of modern human jaws since mandible length is more or less equivalent in Homo sapiens and H. floresiensis. The mechanical attributes of the Liang Bua mandibles are consistent with previous inferences that masticatory loads were reduced relative to australopiths but remained elevated relative to modern Homo.

  9. Geometric properties and comparative biomechanics of Homo floresiensis mandibles.

    PubMed

    Daegling, David J; Patel, Biren A; Jungers, William L

    2014-03-01

    The hypodigm of Homo floresiensis from the cave of Liang Bua on Flores Island in the archipelago of Indonesia includes two mandibles (LB1/2 and LB6/1). The morphology of their symphyses and corpora has been described as sharing similarities with both australopiths and early Homo despite their Late Pleistocene age. Although detailed morphological comparisons of these mandibles with those of modern and fossil hominin taxa have been made, a functional analysis in the context of masticatory biomechanics has yet to be performed. Utilizing data on cortical bone geometry from computed tomography scans, we compare the mechanical attributes of the LB1 and LB6 mandibles with samples of modern Homo, Pan, Pongo, and Gorilla, as well as fossil samples of Paranthropus robustus, Australopithecus africanus and South African early Homo. Structural stiffness measures were derived from the geometric data to provide relative measures of mandibular corpus strength under hypothesized masticatory loading regimes. These mechanical variables were evaluated relative to bone area, mandibular length and estimates of body size to assess their functional affinities and to test the hypothesis that the Liang Bua mandibles can be described as scaled-down variants of either early hominins or modern humans. Relative to modern hominoids, the H. floresiensis material appears to be relatively strong in terms of rigidity in torsion and transverse bending, but is relatively weak under parasagittal bending. Thus, they are 'robust' relative to modern humans (and comparable with australopiths) under some loads but not others. Neither LB1 nor LB6 can be described simply as 'miniaturized' versions of modern human jaws since mandible length is more or less equivalent in Homo sapiens and H. floresiensis. The mechanical attributes of the Liang Bua mandibles are consistent with previous inferences that masticatory loads were reduced relative to australopiths but remained elevated relative to modern Homo. PMID

  10. Chemical and light absorption properties of humic-like substances from biomass burning emissions under controlled combustion experiments

    NASA Astrophysics Data System (ADS)

    Park, Seung Shik; Yu, Jaemyeong

    2016-07-01

    PM2.5 samples from biomass burning (BB) emissions of three types - rice straw (RS), pine needles (PN), and sesame stems (SS) - were collected through laboratory-controlled combustion experiments and analyzed for the mass, organic and elemental carbon (OC and EC), water-soluble organic carbon (WSOC), humic-like substances (HULIS), and water soluble inorganic species (Na+, NH4+, K+, Ca2+, Mg2+, Cl-, NO3-, SO42-, and oxalate). The combustion experiments were carried out at smoldering conditions. Water-soluble HULIS in BB samples was isolated using a one-step solid phase extraction method, followed by quantification with a total organic carbon analyzer. This study aims to explore chemical and light absorption characteristics of HULIS from BB emissions. The contributions of HULIS (=1.94 × HULIS-C) to PM2.5 emissions were observed to be 29.5 ± 2.0, 15.3 ± 3.1, and 25.8 ± 4.0%, respectively, for RS, PN, and SS smoke samples. Contributions of HULIS-C to OC and WSOC for the RS, PN, and SS burning emissions were 0.26 ± 0.03 and 0.63 ± 0.05, 0.15 ± 0.04 and 0.36 ± 0.08, and 0.29 ± 0.08 and 0.51 ± 0.08, respectively. Light absorption by the water extracts from BB aerosols exhibited strong wavelength dependence, which is characteristic of brown carbon spectra with a sharply increasing absorption as wavelength decreases. The average absorption Ångström exponents (AAE) of the water extracts (WSOC) fitted between wavelengths of 300-400 nm were 8.3 (7.4-9.0), 7.4 (6.2-8.5), and 8.0 (7.1-9.3) for the RS, PN, and SS burning samples, which are comparable to the AAE values of BB samples reported in previous publications (e.g., field and laboratory chamber studies). The average mass absorption efficiencies of WSOC measured at 365 nm (MAE365) were 1.37 ± 0.23, 0.86 ± 0.09, and 1.38 ± 0.21 m2/gṡC for RS, PN, and SS burning aerosols, respectively. Correlations of total WSOC, hydrophilic WSOC (= total WSOC-HULIS-C), and HULIS-C concentrations in solution with the light

  11. Comparative x-ray absorption spectroscopy study of Co-doped SnO2 and TiO2

    NASA Astrophysics Data System (ADS)

    Lussier, A.; Dvorak, J.; Idzerda, Y. U.; Ogale, S. B.; Shinde, S. R.; Choudary, R. J.; Venkatesan, T.

    2004-06-01

    We performed x-ray absorption spectroscopy measurements at the cobalt L2,3 edge and the oxygen K edge of Co-doped SnO2 and Co-doped TiO2. Our measurements confirm that doped cobalt atoms are in the same local environment in both compounds. Furthermore, the results support the idea that cobalt atoms occupy substitutional cation sites. Additionally, the oxygen spectral shapes offer insight into a possible cause for the observed giant magnetic moment of cobalt atoms present in SnO2, but not in TiO2.

  12. A Comparative Study of the CO2 Absorption in Some Solvent-Free Alkanolamines and in Aqueous Monoethanolamine (MEA).

    PubMed

    Barzagli, Francesco; Mani, Fabrizio; Peruzzini, Maurizio

    2016-07-01

    The neat secondary amines 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(isopropylamino)ethanol, 2-(benzylamino)ethanol and 2-(butylamino)ethanol react with CO2 at 50-60 °C and room pressure yielding liquid carbonated species without their dilution with any additional solvent. These single-component absorbents have the theoretical CO2 capture capacity of 0.50 (mol CO2/mol amine) due to the formation of the corresponding amine carbamates and protonated amines that were identified by the (13)C NMR analysis. These single-component absorbents were used for CO2 capture (15% and 40% v/v in air) in two series of different procedures: (1) batch experiments aimed at investigating the efficiency and the rate of CO2 capture; (2) continuous cycles of absorption-desorption carried out in packed columns with absorption temperatures brought at 50-60 °C and desorption temperatures at 100-120 °C at room pressure. A number of different amines and experimental setups gave CO2 capture efficiency greater than 90%. For comparison purposes, 30 wt % aqueous MEA was used for CO2 capture under the same operational conditions described for the solvent-free amines. The potential advantages of solvent-free alkanolamines over aqueous MEA in the CO2 capture process were discussed. PMID:27294832

  13. Structural, Magnetic, and Microwave-Absorption Properties of Nanocrystalline Ca(MnSn) x Fe12-2 x O19 Ferrites

    NASA Astrophysics Data System (ADS)

    Ali-Sharbati; Amiri, G. R.; Mousarezaei, R.

    2015-02-01

    Nanoparticles of Ca(MnSn) x Fe12-2 x O19 with x ranging from 0.00 to 0.6 in steps of 0.2 were prepared by use of the citrate precursor method. The structural, microwave-absorption, and magnetic properties of these ferrites were determined by use of different characterization techniques. The morphology of the ferrite powders was investigated by transmission electron microscopy (TEM). X-ray diffraction (XRD) was used for structural and micro-structural studies, and revealed that the samples had an M-type hexagonal structure. The crystallite size for each sample was calculated by use of the Scherrer formula for the most intense peak (411) and the results were compared with those obtained from TEM images of the samples. The particle size of the powder varied from 60 to 36 nm. Magnetic measurements were performed by vibrating sample magnetometry (VSM) at room temperature. The microwave-absorption properties of ferrite (70 wt.%)-polymer (30 wt.%) composites 2 mm thick were investigated by vector network analysis (VNA) in the frequency range 12-20 GHz. The ferrite for which x = 0.4 had a minimum reflection loss of -29 dB at 17.3 GHz with a -15 dB bandwidth over the extended frequency ranges 12.9-14.5 GHz and 16.7-18 GHz. The minimum loss reached -32 dB at frequency of 17 GHz when the total amount of Mn2+ and Sn4+ ions was 0.6. These results suggest that the synthesized magnetic composites can be used as effective microwave absorbers in military applications (radar cross-section reduction).

  14. Magnetic and microwave absorption properties of rare earth ions (Sm3+, Er3+) doped strontium ferrite and its nanocomposites with polypyrrole

    NASA Astrophysics Data System (ADS)

    Luo, Juhua; Xu, Yang; Mao, Hongkai

    2015-05-01

    M-type strontium ferrite substituted by RE (RE=Sm3+, Er3+) were prepared via a sol-gel method. Polypyrrole (PPy)/ferrite nanocomposites (with 20 wt% ferrite) were prepared by in situ polymerization method in the presence of ammonium persulfate. Effect of the substituted RE ions on structure, magnetic properties and microwave absorption properties were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and vector network analyzer. All XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. The crystallite size of synthesized particle is within the range of 22.2-38.1 nm. The structural in character of the composites were investigated with FT-IR analysis. It shows that the ferrite successfully packed by PPy. TEM photographs show that the particle size had grown up to 50-100 nm after coating with PPy. In the magnetization for the PPy/SrSm0.3Fe11.7O19 (SrEr0.3Fe11.7O19) composites, the coercivity (Hc) of the composites both increased compared with the undoped composite while the saturation magnetization (Ms) appeared opposite change with different RE ions. Considering the electromagnetic loss and impedance matching comprehensively, the Er-doped ferrite/PPy composite got the better microwave absorption performance with the maximum RL value of -24.01 dB in 13.8 GHz at 3.0 mm. And its width (<-10 dB) has reached 7.2 GHz which has covered the whole Ku band.

  15. Synthesis and Microwave Absorption Properties of BaTiO3-polypyrrole Composite

    NASA Astrophysics Data System (ADS)

    Li, Qiao-ling; Zhang, Cun-rui; Li, Jian-qiang

    2010-10-01

    BaTiO3 powders are prepared by sol-gel method by cotton template. Polypyrrole is prepared by chemical oxidation route in the emulsion polymerization system. Then BaTiO3-polypyrrole composites with different mixture ratios are prepared by as-prepared material. The structure, morphology, and properties of the composites are characterized with Infrared spectrum, X-ray diffraction, scanning electron microscope, and net-wok analyzer. The complex permittivity and reflection loss of the composites are measured at different microwave frequencies in S-band and C-band (0.03-6 GHz) employing vector network analyzer model PNA 3629D vector. The effect of the mass ratio of BaTiO3 to polypyrrole on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of BaTiO3-polypyrrole composite is proposed. The BaTiO3-polypyrrole composite can find applications in suppression of electromagnetic interference and reduction of radar signature.

  16. Controlled synthesis and microwave absorption property of chain-like co flower.

    PubMed

    Wang, Chao; Hu, Surong; Han, Xijiang; Huang, Wen; Tian, Lunfu

    2013-01-01

    Chain-like Co flower is synthesized by simply modulating the reaction conditions via a facile liquid-phase reduction method. The morphology evolution process and transformation mechanism from particle to flower and finally to chain-like flower have been systematically investigated. [001] is the preferred growth orientation due to the existence of easy magnetic axis. The microwave loss mechanism can be attributed to the synergistic effect of magnetic loss and dielectric loss, while magnetic loss is the main loss mechanism. In addition, the special microstructure of chain-like Co flower may further enhance microwave attenuation. The architectural design of functional material morphology is critical for improving its property toward future application.

  17. Development of an in-situ structure/photo-absorption coincident measurement system for precise structure-optical property relationship research at SPring-8

    NASA Astrophysics Data System (ADS)

    Kim, Jungeun; Kato, Kenichi; Moritomo, Yutaka; Takata, Masaki

    2010-06-01

    We have developed the structure and optical property coincident measurement system equipped with the photo-absorption system to the Large Debye-Scherrer Camera at BL44B2 of the SPring-8. Both photo-absorption detecting systems, the Si pin-photo diode for a 532 nm CW laser and the absorption spectrum covered the range of UV-IR (200˜1400 nm) for a white beam, are adopted. In order to verify the coincident measurement system, the X-ray powder diffraction and photo-absorption with the cyanide complex were performed individually and simultaneously under the temperature changes. As a result, the coincident measurement system performed successfully the one-to-one corresponding measurement between X-ray diffraction and photo-absorption. In addition, the monitoring of the photo-absorption informed us the property change of the material for the measurement condition and the sample transformation by temperature, laser etc. as well as damage by high-brilliance synchrotron radiation X-ray beam.

  18. Evaluation of in vitro absorption, distribution, metabolism, and excretion (ADME) properties of mitragynine, 7-hydroxymitragynine, and mitraphylline.

    PubMed

    Manda, Vamshi K; Avula, Bharathi; Ali, Zulfiqar; Khan, Ikhlas A; Walker, Larry A; Khan, Shabana I

    2014-05-01

    Mitragyna speciosa (kratom) is a popular herb in Southeast Asia, which is traditionally used to treat withdrawal symptoms associated with opiate addiction. Mitragynine, 7-hydroxymitragynine, and mitraphylline are reported to be the central nervous system active alkaloids which bind to the opiate receptors. Mitraphylline is also present in the bark of Uncaria tomentosa (cat's claw). Several therapeutic properties have been reported for these compounds but limited information is available on the absorption and distribution properties. This study focuses on evaluating the absorption, distribution, metabolism, and excretion (ADME) properties of these compounds and their effect on major efflux transporter P-glycoprotein, using in vitro methods. Quantitative analysis was performed by the Q-TOF LC-MS system. Mitragynine was unstable in simulated gastric fluid with 26 % degradation but stable in simulated intestinal fluid. 7-Hydroxymitragynine degraded up to 27 % in simulated gastric fluid, which could account for its conversion to mitragynine (23 %), while only 6 % degradation was seen in simulated intestinal fluid. Mitraphylline was stable in simulated gastric fluid but unstable in simulated intestinal fluid (13.6 % degradation). Mitragynine and 7-hydroxymitragynine showed moderate permeability across Caco-2 and MDR-MDCK monolayers with no significant efflux. However, mitraphylline was subjected to efflux mediated by P-glycoprotein in both Caco-2 and MDR-MDCK monolayers. Mitragynine was found to be metabolically stable in both human liver microsomes and S9 fractions. In contrast, both 7-hydroxymitragynine and mitraphylline were metabolized by human liver microsomes with half-lives of 24 and 50 min, respectively. All three compounds exhibited high plasma protein binding (> 90 %) determined by equilibrium dialysis. Mitragynine and 7-hydroxymitragynine inhibited P-glycoprotein with EC50 values of 18.2 ± 3.6 µM and 32.4 ± 1.9 µM, respectively

  19. Evaluation of in vitro absorption, distribution, metabolism, and excretion (ADME) properties of mitragynine, 7-hydroxymitragynine, and mitraphylline.

    PubMed

    Manda, Vamshi K; Avula, Bharathi; Ali, Zulfiqar; Khan, Ikhlas A; Walker, Larry A; Khan, Shabana I

    2014-05-01

    Mitragyna speciosa (kratom) is a popular herb in Southeast Asia, which is traditionally used to treat withdrawal symptoms associated with opiate addiction. Mitragynine, 7-hydroxymitragynine, and mitraphylline are reported to be the central nervous system active alkaloids which bind to the opiate receptors. Mitraphylline is also present in the bark of Uncaria tomentosa (cat's claw). Several therapeutic properties have been reported for these compounds but limited information is available on the absorption and distribution properties. This study focuses on evaluating the absorption, distribution, metabolism, and excretion (ADME) properties of these compounds and their effect on major efflux transporter P-glycoprotein, using in vitro methods. Quantitative analysis was performed by the Q-TOF LC-MS system. Mitragynine was unstable in simulated gastric fluid with 26 % degradation but stable in simulated intestinal fluid. 7-Hydroxymitragynine degraded up to 27 % in simulated gastric fluid, which could account for its conversion to mitragynine (23 %), while only 6 % degradation was seen in simulated intestinal fluid. Mitraphylline was stable in simulated gastric fluid but unstable in simulated intestinal fluid (13.6 % degradation). Mitragynine and 7-hydroxymitragynine showed moderate permeability across Caco-2 and MDR-MDCK monolayers with no significant efflux. However, mitraphylline was subjected to efflux mediated by P-glycoprotein in both Caco-2 and MDR-MDCK monolayers. Mitragynine was found to be metabolically stable in both human liver microsomes and S9 fractions. In contrast, both 7-hydroxymitragynine and mitraphylline were metabolized by human liver microsomes with half-lives of 24 and 50 min, respectively. All three compounds exhibited high plasma protein binding (> 90 %) determined by equilibrium dialysis. Mitragynine and 7-hydroxymitragynine inhibited P-glycoprotein with EC50 values of 18.2 ± 3.6 µM and 32.4 ± 1.9 µM, respectively

  20. Photon absorption and emission properties of 7 Å SiC nanoclusters: Electronic gap, surface state, and quantum size effect

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoxiao; Chen, Xifang; Fan, Baolu; Zhang, Yumeng; Fan, Jiyang

    2016-07-01

    People know little experimentally about the physical properties of the SiC nanoclusters with sizes of a couple of angstroms. Herein, we study the electronic structure and light absorption/emission properties of the SiC nanoclusters with an average diameter of 7 Å that are fabricated by diminishing the sizes of the SiC microcrystals under high pressure and high temperature. The results reveal that the SiC nanoclusters have an indirect energy gap of 5.1 eV. Unlike the case of larger SiC nanocrystals, the luminescence of the SiC nanoclusters is dominated by two types of oxygen-related surface defects, and the maximum of their photoluminescence/photoluminescence excitation spectrum lies at 4.1/3.3 and 3.8/3.0 eV, respectively. The energy gap of the SiC nanoparticles with reference to bulk value is found to be inversely proportional to the diameter to the power 0.97, which shows slower increase of energy gap with decreasing size than what is predicted by using the first-principles calculations.

  1. Excellent improvement in the static and dynamic magnetic properties of carbon coated iron nanoparticles for microwave absorption

    NASA Astrophysics Data System (ADS)

    Khani, Omid; Shoushtari, Morteza Zargar; Farbod, Mansoor

    2015-11-01

    Carbon coated iron nanoparticles were synthesized, using a simple arc-discharge method. The morphology and the internal structure of the core/shell nanoparticles were studied, using field emission scanning electron microscopy and transmission electron microscopy. X-ray diffraction analysis showed that both magnetic α-Fe and nonmagnetic γ-Fe phases existed in the as-prepared particles. In order to improve the static and dynamic magnetic properties of the core/shell nanoparticles, the produced nanocapsules were annealed in argon atmosphere at two different temperatures. Hysteresis loops revealed that the value of the saturation magnetization (MS) increased more than 4.1 times of its original value by annealing and this led to 70% increase in the imaginary part of the permeability. Phase analysis showed that heat treatment eliminated the nonmagnetic γ-Fe phase completely. The reflection loss plots were studied for composite layers containing 20 vol% of the annealed and not annealed nanocapsules. One of the absorber layers which contained annealed nanocapsules showed at least -10 dB loss in the whole G, C, X and Ku frequency bands and the optimal absorption exceeded -37 dB at 5.8 GHz for the as-prepared sample with a thickness of 3.2 mm. The results revealed that the magnetic properties of the arc-made Fe/C core/shell nanoparticle can be improved significantly by annealing in argon.

  2. Properties of damped Ly α absorption systems and star-forming galaxies in semi-analytic models at z = 2

    NASA Astrophysics Data System (ADS)

    Berry, Michael; Somerville, Rachel S.; Gawiser, Eric; Maller, Ariyeh H.; Popping, Gergö; Trager, Scott C.

    2016-05-01

    We investigate predictions from semi-analytic cosmological models of galaxy formation for the properties of star-forming galaxies (SFGs) and damped Ly α absorption systems (DLAS), and the relationship between these two populations. Our models reproduce fairly well the observed distributions of redshift, stellar mass, star formation rate (SFR), and dust extinction for z ˜ 2 SFGs. We predict that DLA hosts span a broad range of properties, with broad and relatively flat distributions of stellar and halo mass, SFR, and luminosity. The photometric colours of DLA host galaxies trace the colours of galaxies with similar luminosities, but the majority are much fainter than the limits of most existing surveys of SFGs. Generally, DLA host galaxies and SFGs at z = 2 follow similar trends between stellar mass, DLA cross-section, cold gas fraction, SFR, metallicity, and dust extinction as the global population of galaxies with the same stellar mass. Since DLAS select galaxies with larger cold gas masses, they tend to have larger cold gas fractions, lower metallicities, higher SFRs, and less dust extinction than galaxies at the same stellar mass. Our models reproduce the observed relations between impact parameter, column density, and metallicity, suggesting that the sizes of the gas discs giving rise to DLAS in our models are roughly correct. We find that molecular fractions and SFRs are in general significantly lower at the location of the DLA line of sight than the galaxy-averaged value.

  3. Comparing Data Sets: Implicit Summaries of the Statistical Properties of Number Sets

    ERIC Educational Resources Information Center

    Morris, Bradley J.; Masnick, Amy M.

    2015-01-01

    Comparing datasets, that is, sets of numbers in context, is a critical skill in higher order cognition. Although much is known about how people compare single numbers, little is known about how number sets are represented and compared. We investigated how subjects compared datasets that varied in their statistical properties, including ratio of…

  4. Adhesion of Mineral and Soot Aerosols can Strongly Affect their Scattering and Absorption Properties

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Dlugach, Jana M.

    2012-01-01

    We use the numerically exact superposition T-matrix method to compute the optical cross sections and the Stokes scattering matrix for polydisperse mineral aerosols (modeled as homogeneous spheres) covered with a large number of much smaller soot particles. These results are compared with the Lorenz-Mie results for a uniform external mixture of mineral and soot aerosols. We show that the effect of soot particles adhering to large mineral particles can be to change the extinction and scattering cross sections and the asymmetry parameter quite substantially. The effect on the phase function and degree of linear polarization can be equally significant.

  5. Influence of matching thickness on the absorption properties of doped barium ferrites at microwave frequencies

    NASA Astrophysics Data System (ADS)

    Ghasemi, A.; Saatchi, A.; Salehi, M.; Hossienpour, A.; Morisako, A.; Liu, X.

    2006-02-01

    The development and characterization of hexagonal ferrite powders of BaFe9Mn1.5Ti1.5O19, BaFe9Mn1.5Co1.5O19, and BaFe9Ti1.5Co1.5O19 as the microwave absorbers have been investigated. The ferrites were fabricated by conventional ceramic technology. The developed ferrite powders 80% by weight were mixed with polyvinylchloride plasticizer and fired to form rubber-ferrite with the thickness of 1.5 mm, 2 mm and 2.5 mm. XRD was used to identify structures of the samples. The magnetoplumbite structures for all the samples have been formed. Vibrating sample magnetometer was used to determine the hysteresis loops of barium ferrite and BaFe9Mn1.5Ti1.5O19 at room temperature. The vector network analyzers in the frequency range of 12 to 20 GHz have measured the reflection loss properties of rubber-ferrite. It was concluded that BaFe9Mn1.5Ti1.5O19 with thickness of 2 mm could be designed as a wide-band microwave absorber. By SEM, the size and morphology of grains in BaFe9Mn1.5Ti1.5O19 ferrite were examined. The results showed that ferrite with grain size of 5 μm do not have any impurities.

  6. Climatology of aerosol optical properties and black carbon mass absorption cross section at a remote high-altitude site in the western Mediterranean Basin

    NASA Astrophysics Data System (ADS)

    Pandolfi, M.; Ripoll, A.; Querol, X.; Alastuey, A.

    2014-06-01

    Aerosol light scattering (σsp), backscattering (σbsp) and absorption (σap) were measured at Montsec (MSC; 42°3' N, 0°44' E, 1570 m a.s.l.), a remote high-altitude site in the western Mediterranean Basin. Mean (±SD) σsp, σbsp and σap were 18.9 ± 20.8, 2.6 ± 2.8 and 1.5 ± 1.4 Mm-1, respectively at 635 nm during the period under study (June 2011-June 2013). Mean values of single-scattering albedo (SSA, 635 nm), the scattering Ångström exponent (SAE, 450-635 nm), backscatter-to-scatter ratio (B / S, 635 nm), asymmetry parameter (g, 635 nm), black carbon mass absorption cross section (MAC, 637 nm) and PM2.5 mass scattering cross section (MSCS, 635 nm) were 0.92 ± 0.03, 1.56 ± 0.88, 0.16 ± 0.09, 0.53 ± 0.16, 10.9 ± 3.5 m2 g-1 and 2.5 ± 1.3 m2 g-1, respectively. The scattering measurements performed at MSC were in the medium/upper range of values reported by Andrews et al. (2011) for other mountaintop sites in Europe due to the frequent regional recirculation scenarios (SREG) and Saharan dust episodes (NAF) occurring mostly in spring/summer and causing the presence of polluted layers at the MSC altitude. However, the development of upslope winds and the possible presence of planetary boundary layer air at MSC altitude in summer may also have contributed to the high scattering observed. Under these summer conditions no clear diurnal cycles were observed for the measured extensive aerosol optical properties (σsp, σbsp and σap). Conversely, low σsp and σap at MSC were measured during Atlantic advections (AA) and winter regional anticyclonic episodes (WREG) typically observed during the cold season in the western Mediterranean. Therefore, a season-dependent decrease in the magnitude of aerosol extensive properties was observed when MSC was in the free troposphere, with the highest free-troposphere vs. all-data difference observed in winter and the lowest in spring/summer. The location of MSC station allowed for a reliable characterization of aerosols

  7. Electronic properties of superconductors studied using photo induced activation of microwave absorption (PIAMA)

    SciTech Connect

    Feenstra, B.J.; Schooveld, W.A.; Bos, C.

    1995-12-31

    Electronic properties of superconductors are contemporarily being studied using many different experimental techniques, among which infrared spectrometry, photoelectron spectroscopy and microwave cavity techniques play an important role. The data analysis, however, is complicated by the fact that in these materials the phonon-frequency range overlaps with the one in which the energy gap is expected. This problem can be circumvented by making use of two different sources, one to induce the excitations (the Free Electron Laser in Nieuwegein, The Netherlands, FELIX), and one to study the behavior of these excitations (i.e. quasiparticles). In our case the latter source is monochromatic microwave radiation, transmitted through a thin superconducting film. We measured both a conventional superconductor (NbN, T{sub c} = 17 K) and a high T{sub c} superconductor (SmBa{sub 2}Cu{sub 3}O{sub 7-{delta}}, T{sub c} = 92 K). For NbN we observed a positive change in transmission, followed by a relaxation to a transmission smaller than the original value, after which the starting situation was restored within {approximately} 100 {mu}s. In case of SmBa{sub 2}Cu{sub 3}O{sub 7-{delta}}, the changes persisted above T{sub c}. At very low temperatures we observed slow oscillations ({approximately} 4kHz) in the induced signal, which were absent in NbN. The long time scales can possibly be explained by the so-called bottleneck, i.e. quasiparticles excited with a lot of excess energy lose part of their energy by exciting other quasiparticles. In this case the quasiparticle lifetime is enhanced considerably. The oscillations point towards an intrinsic difference of the low energy excitations, i.e. the symmetry of the pairing.

  8. Unveiling the intrinsic X-ray properties of broad absorption line quasars with a relatively unbiased sample

    SciTech Connect

    Morabito, Leah K.; Dai, Xinyu; Leighly, Karen M.; Sivakoff, Gregory R.; Shankar, Francesco

    2014-05-01

    There is growing evidence of a higher intrinsic fraction of broad absorption line quasars (BALQSOs) than that obtained in optical surveys, on which most previous X-ray studies of BALQSOs have focused. Here we present Chandra observations of 18 BALQSOs at z ∼ 2, selected from a near-infrared (Two Micron All Sky Survey) sample, where the BALQSO fraction is likely to be close to the intrinsic fraction. We measure photon indices using the stacked spectra of the optically faint (i – K{sub s} ≥ 2.3 mag) and optically bright (i – K{sub s} < 2.3 mag) samples to be Γ ≅ 1.5-2.1. We constrain their intrinsic column density by modeling the X-ray fractional hardness ratio, finding a mean column density of 3.5 × 10{sup 22} cm{sup –2} assuming neutral absorption. We incorporate Sloan Digital Sky Survey optical measurements (rest frame UV) to study the broadband spectral index between the X-ray and UV bands, and compare this to a large sample of normal quasars. We estimate that the optically faint BALQSOs are X-ray weaker than the optically bright ones, and the entire sample of BALQSOs are intrinsically X-ray weak when compared to normal active galactic nuclei (AGNs). Correcting for magnification of X-ray emission via gravitational lensing by the central black hole viewed at large inclination angles makes these BALQSOs even more intrinsically X-ray weak. Finally, we estimate AGN kinetic feedback efficiencies of a few percent for an X-ray wind of 0.3c in high-ionization BALQSOs. Combined with energy carried by low-ionization BALQSOs and UV winds, the total kinetic energy in BALQSOs can be sufficient to provide AGN kinetic feedback required to explain the co-evolution between black holes and host galaxies.

  9. Microwave Absorption Properties of Iron Nanoparticles Prepared by Ball-Milling

    NASA Astrophysics Data System (ADS)

    Chu, Xuan T. A.; Ta, Bach N.; Ngo, Le T. H.; Do, Manh H.; Nguyen, Phuc X.; Nam, Dao N. H.

    2016-05-01

    A nanopowder of iron was prepared using a high-energy ball milling method, which is capable of producing nanoparticles at a reasonably larger scale compared to conventional chemical methods. Analyses using x-ray diffraction and magnetic measurements indicate that the iron nanoparticles are a single phase of a body-centered cubic structure and have quite stable magnetic characteristics in the air. The iron nanoparticles were then mixed with paraffin and pressed into flat square plates for free-space microwave transmission and reflection measurements in the 4-8 GHz range. Without an Al backing plate, the Fe nanoparticles seem to only weakly absorb microwave radiation. The reflected signal S 11 drops to zero and a very large negative value of reflection loss ( RL) are observed for Al-backed samples, suggesting the existence of a phase matching resonance near frequency f ˜ 6 GHz.

  10. Nonlinear optical absorption and switching properties of gold nanoparticle doped SiO2-TiO2 sol-gel films.

    PubMed

    Venkatram, N; Kumar, R Sai Santosh; Rao, D Narayana; Medda, S K; De, Sucheta; De, Goutam

    2006-07-01

    The nonlinear optical absorption and switching properties of sol-gel derived of Au nanoparticle doped SiO2-TiO2 sol-gel films having different Au-surface plasmon absorption positions are reported in this paper. The Au nanoparticles are embedded in SiO2 and SiO2-TiO2 mixed glassy film matrices with different refractive index values. To study the nonlinear absorption properties, lasers with three different wavelengths are used. The optical switching behavior is studied by using the pump-probe technique with 532 nm as the excitation wavelength. Ground state conduction band, surface plasmon band, and the free carrier band are taken as three level model to explain theoretically the obtained RSA and SA behaviors.

  11. A model predicting the evolution of ice particle size spectra and radiative properties of cirrus clouds. Part 2: Dependence of absorption and extinction on ice crystal morphology

    NASA Technical Reports Server (NTRS)

    Mitchell, David L.; Arnott, W. Patrick

    1994-01-01

    This study builds upon the microphysical modeling described in Part 1 by deriving formulations for the extinction and absorption coefficients in terms of the size distribution parameters predicted from the micro-physical model. The optical depth and single scatter albedo of a cirrus cloud can then be determined, which, along with the asymmetry parameter, are the input parameters needed by cloud radiation models. Through the use of anomalous diffraction theory, analytical expressions were developed describing the absorption and extinction coefficients and the single scatter albedo as functions of size distribution parameters, ice crystal shapes (or habits), wavelength, and refractive index. The extinction coefficient was formulated in terms of the projected area of the size distribution, while the absorption coefficient was formulated in terms of both the projected area and mass of the size distribution. These properties were formulated as explicit functions of ice crystal geometry and were not based on an 'effective radius.' Based on simulations of the second cirrus case study described in Part 1, absorption coefficients predicted in the near infrared for hexagonal columns and rosettes were up to 47% and 71% lower, respectively, than absorption coefficients predicted by using equivalent area spheres. This resulted in single scatter albedos in the near-infrared that were considerably greater than those predicted by the equivalent area sphere method. Reflectances in this region should therefore be underestimated using the equivalent area sphere approach. Cloud optical depth was found to depend on ice crystal habit. When the simulated cirrus cloud contained only bullet rosettes, the optical depth was 142% greater than when the cloud contained only hexagonal columns. This increase produced a doubling in cloud albedo. In the near-infrared (IR), the single scatter albedo also exhibited a significant dependence on ice crystal habit. More research is needed on the

  12. Electromagnetic wave absorption properties of NiCoP alloy nanoparticles decorated on reduced graphene oxide nanosheets

    NASA Astrophysics Data System (ADS)

    Ye, Weichun; Fu, Jiajia; Wang, Qin; Wang, Chunming; Xue, Desheng

    2015-12-01

    NiCoP alloy nanoparticles supported on reduced graphene oxide (NiCoP/RGO) are synthesized by in situ co-reduction of Ni2+, Co2+ and graphene oxide (GO) with sodium hypophosphite in a one-pot reaction. This synthesis route is simple and can be used for industrial preparation. The different molar ratios of Ni/Co can be obtained by changing the molar ratio of their salts in the reaction bath. The effect of annealing temperature on the crystal structure of NiCoP alloys has been further investigated. After 500 °C annealing, NiCoP alloys exhibit good crystallinity. The as-prepared NiCoP/RGO composites demonstrate high dielectric constant and magnetic loss in the frequency range of 2-18 GHz due to the conductive and ferromagnetic behavior. Also, their coercivity and magnetization strength are decreased from magnetic measurement with the increase of Ni content. As the molar ratio of Ni/Co is 3:1, the maximum value of the reflection loss reaches to -17.84 dB. Furthermore, the NiCoP/RGO composites have better corrosion resistance than traditional iron series magnetic nanoparticles. It is expected that the composites with the thin, light-weighted and broadband absorbing and good anti-corrosion properties will have a great potential for electromagnetic wave absorption applications.

  13. Optical absorption and fluorescence properties of Er{sup 3+}/Yb{sup 3+} codoped lead bismuth alumina borate glasses

    SciTech Connect

    Goud, K. Krishna Murthy Reddy, M. Chandra Shekhar Rao, B. Appa

    2014-04-24

    Lead bismuth alumina borate glasses codoped with Er{sup 3+}/Yb{sup 3+} were prepared by melt quenching technique. Optical absorption, FTIR and photoluminescence spectra of these glasses have been studied. Judd-Ofelt theory has been applied to to the f ↔ f transitions for evaluating Ω{sub 2}, Ω{sub 4} and Ω{sub 6} parameters. Radiative properties like branching ratio β{sub r} and the radiative life time τ{sub R} have been determined on the basis of Judd-Ofelt theory. Upconversion emissions have been observed under 980nm laser excitation at room temperature. Green and red up-conversion emissions are centered at 530, 550 and 656 nm corresponding to {sup 2}H{sub 11/2}→{sup 4}I{sub 15/2}, {sup 4}S{sub 3/2}→{sup 4}I{sub 15/2} and {sup 4}F{sub 9/2}→{sup 4}I{sub 15/2} transitions of Er{sup 3+} respectively. The results obtained are discussed quantitatively based on the energy transfer between Yb{sup 3+} and Er{sup 3+}.

  14. Multispectral imaging of absorption and scattering properties of in vivo exposed rat brain using a digital red-green-blue camera

    NASA Astrophysics Data System (ADS)

    Yoshida, Keiichiro; Nishidate, Izumi; Ishizuka, Tomohiro; Kawauchi, Satoko; Sato, Shunichi; Sato, Manabu

    2015-05-01

    In order to estimate multispectral images of the absorption and scattering properties in the cerebral cortex of in vivo rat brain, we investigated spectral reflectance images estimated by the Wiener estimation method using a digital RGB camera. A Monte Carlo simulation-based multiple regression analysis for the corresponding spectral absorbance images at nine wavelengths (500, 520, 540, 560, 570, 580, 600, 730, and 760 nm) was then used to specify the absorption and scattering parameters of brain tissue. In this analysis, the concentrations of oxygenated hemoglobin and that of deoxygenated hemoglobin were estimated as the absorption parameters, whereas the coefficient a and the exponent b of the reduced scattering coefficient spectrum approximated by a power law function were estimated as the scattering parameters. The spectra of absorption and reduced scattering coefficients were reconstructed from the absorption and scattering parameters, and the spectral images of absorption and reduced scattering coefficients were then estimated. In order to confirm the feasibility of this method, we performed in vivo experiments on exposed rat brain. The estimated images of the absorption coefficients were dominated by the spectral characteristics of hemoglobin. The estimated spectral images of the reduced scattering coefficients had a broad scattering spectrum, exhibiting a larger magnitude at shorter wavelengths, corresponding to the typical spectrum of brain tissue published in the literature. The changes in the estimated absorption and scattering parameters during normoxia, hyperoxia, and anoxia indicate the potential applicability of the method by which to evaluate the pathophysiological conditions of in vivo brain due to the loss of tissue viability.

  15. Excellent electromagnetic absorption properties of poly(3,4-ethylenedioxythiophene)-reduced graphene oxide-Co3O4 composites prepared by a hydrothermal method.

    PubMed

    Liu, Pan-Bo; Huang, Ying; Sun, Xu

    2013-12-11

    The ternary composites of poly(3,4-ethylenedioxythiophene)-reduced graphene oxide-Co3O4 (PEDOT-RGO-Co3O4) were synthesized and the electromagnetic absorption property of the composites was investigated. The structure of the composites was characterized with Fourier-transform infrared spectra, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscope. The electromagnetic parameters indicate the enhanced electromagnetic absorption property of the composites was attributed to the better impedance matching. On the basis of the above characterization, an electromagnetic complementary theory was proposed to explain the impedance matching. It can be found that the maximum reflection loss of PEDOT-RGO-Co3O4 can reach -51.1 dB at 10.7 GHz, and the bandwidth exceeding -10 dB is 3.1 GHz with absorber thickness of 2.0 mm. Therefore, the PEDOT-RGO-Co3O4 composites, with such excellent electromagnetic absorption properties and wide absorption bandwidth, can be used as a new kind of candidate for microwave absorbing materials. PMID:24218981

  16. [Variations in the optical absorption and attenuation properties of cultured phytoplankton and their relationships with cell size].

    PubMed

    Zhou, Wen; Sun, Zhao-Hua; Cao, Wen-Xi; Wang, Gui-Fen

    2012-12-01

    The spectral absorption and attenuation coefficients of 16 phytoplankton species were measured in the laboratory using acs instrument. Ancillary measurements included particle size distribution and chlorophyll a concentration (Chl a). The results indicated that both algal cell size and Chl a were the two major factors dominating the magnitudes of the spectral absorption and attenuation coefficients. The spectral behaviors of attenuation spectra were dominated by algal cell size, the relationship of them didn't follow the monotonic function. Both the ratio of absorption in blue and red waveband and the spectral slope of absorption coefficient were influenced by the product of algal cell density and squares of cell size rather than algal cell size alone. The relationship between algal cell size and both absorption and attenuation spectra would be interpreted by Mie theory for homogenous sphere, which imply that the heterogeneity and non-spherical shape in algal cell morphology and internal structure have little effect on the inherent association among them.

  17. Comparing contaminated property redevelopment for mandatory and Voluntary Cleanup Programs in California.

    PubMed

    Schwarz, Peter M; Depken, Craig A; Hanning, Alex; Peterson, Kristen

    2009-09-01

    This study uses California data to compare redevelopment for properties subject to mandatory and voluntary cleanup. CalSites are subject to the CERCLA liability approach, while properties in the Voluntary Cleanup Program (VCP) are subject to a risk-based approach (RBA) that allows some contamination to remain for non-residential redevelopment. The expectation is that VCPs will show a greater proportion of industrial redevelopment, which has the least stringent standard, and a smaller proportion of residential redevelopment. The results show an overall trend toward more residential redevelopment of contaminated properties, but consistent with expectations, the trend is weaker for VCP properties than CalSites. PMID:19467568

  18. Sensing Properties of Multiwalled Carbon Nanotubes Grown in MW Plasma Torch: Electronic and Electrochemical Behavior, Gas Sensing, Field Emission, IR Absorption

    PubMed Central

    Majzlíková, Petra; Sedláček, Jiří; Prášek, Jan; Pekárek, Jan; Svatoš, Vojtěch; Bannov, Alexander G.; Jašek, Ondřej; Synek, Petr; Eliáš, Marek; Zajíčková, Lenka; Hubálek, Jaromír

    2015-01-01

    Vertically aligned multi-walled carbon nanotubes (VA-MWCNTs) with an average diameter below 80 nm and a thickness of the uniform VA-MWCNT layer of about 16 μm were grown in microwave plasma torch and tested for selected functional properties. IR absorption important for a construction of bolometers was studied by Fourier transform infrared spectroscopy. Basic electrochemical characterization was performed by cyclic voltammetry. Comparing the obtained results with the standard or MWCNT‐modified screen-printed electrodes, the prepared VA-MWCNT electrodes indicated their high potential for the construction of electrochemical sensors. Resistive CNT gas sensor revealed a good sensitivity to ammonia taking into account room temperature operation. Field emission detected from CNTs was suitable for the pressure sensing application based on the measurement of emission current in the diode structure with bending diaphragm. The advantages of microwave plasma torch growth of CNTs, i.e., fast processing and versatility of the process, can be therefore fully exploited for the integration of surface-bound grown CNTs into various sensing structures. PMID:25629702

  19. Sensing properties of multiwalled carbon nanotubes grown in MW plasma torch: electronic and electrochemical behavior, gas sensing, field emission, IR absorption.

    PubMed

    Majzlíková, Petra; Sedláček, Jiří; Prášek, Jan; Pekárek, Jan; Svatoš, Vojtěch; Bannov, Alexander G; Jašek, Ondřej; Synek, Petr; Eliáš, Marek; Zajíčková, Lenka; Hubálek, Jaromír

    2015-01-01

    Vertically aligned multi-walled carbon nanotubes (VA-MWCNTs) with an average diameter below 80 nm and a thickness of the uniform VA-MWCNT layer of about 16 µm were grown in microwave plasma torch and tested for selected functional properties. IR absorption important for a construction of bolometers was studied by Fourier transform infrared spectroscopy. Basic electrochemical characterization was performed by cyclic voltammetry. Comparing the obtained results with the standard or MWCNT‑modified screen-printed electrodes, the prepared VA-MWCNT electrodes indicated their high potential for the construction of electrochemical sensors. Resistive CNT gas sensor revealed a good sensitivity to ammonia taking into account room temperature operation. Field emission detected from CNTs was suitable for the pressure sensing application based on the measurement of emission current in the diode structure with bending diaphragm. The advantages of microwave plasma torch growth of CNTs, i.e., fast processing and versatility of the process, can be therefore fully exploited for the integration of surface-bound grown CNTs into various sensing structures. PMID:25629702

  20. In vivo estimation of light scattering and absorption properties of rat brain using single reflectance fiber probe during anoxic depolarization

    NASA Astrophysics Data System (ADS)

    Nishidate, Izumi; Yoshida, Keiichiro; Kawauchi, Satoko; Sato, Shunichi; Sato, Manabu

    2015-03-01

    Diffuse reflectance spectroscopy using fiber optic probe is one of most promising technique for evaluating optical properties of biological tissue. We present a method determining the reduced scattering coefficients μs', the absorption coefficients μ a, and tissue oxygen saturation StO2 of in vivo brain tissue using single reflectance fiber probe with two source-collector geometries. In the present study, we performed in vivo recordings of diffuse reflectance spectra and the electrophysiological signals for exposed brain of rats during normoxia, hyperoxia, hypoxia, and anoxia. The time courses of μa in the range from 500 to 584 nm and StO2 indicated the hemodynamic change in cerebral cortex. Time courses of μs' are well correlated with those of μa in the range from 530 to 570 nm, which also reflect the scattering by red blood cells. On the other hand, a fast decrease in μs' at 800 nm were observed after the respiratory arrest and it synchronized with the negative deflection of the extracellular DC potential. It is said that the DC shift coincident with a rise in extracellular potassium and can evoke cell deformation generated by water movement between intracellular and extracellular compartments, and hence the light scattering by tissue. Therefore, the decrease in μs' at 800 after the respiratory arrest is indicative of changes in light scattering by tissue. The results in this study indicate potential of the method to evaluate the pathophysiological and loss of tissue viability in brain tissue.

  1. Investigation of the electromagnetic absorption properties of Ni@TiO2 and Ni@SiO2 composite microspheres with core-shell structure.

    PubMed

    Zhao, Biao; Shao, Gang; Fan, Bingbing; Zhao, Wanyu; Zhang, Rui

    2015-01-28

    In this work, amorphous TiO2 and SiO2-coated Ni composite microspheres were successfully prepared by a two-step method. The phase purity, morphology, and structure of composite microspheres are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). Due to the presence of the insulator SiO2 shell, the core-shell Ni-SiO2 composite microspheres exhibit better antioxidation capability than that of pure Ni microspheres. The core-shell Ni-SiO2 composite microspheres show the best microwave absorption properties than those of pure Ni microspheres and Ni-TiO2 composites. For Ni-SiO2 composite microspheres, an optimal reflection loss (RL) as low as -40.0 dB (99.99% absorption) was observed at 12.6 GHz with an absorber thickness of only 1.5 mm. The effective absorption (below -10 dB, 90% microwave absorption) bandwidth can be adjusted between 3.1 GHz and 14.4 GHz by tuning the absorber thickness in the range of 1.5-4.5 mm. The excellent microwave absorption abilities of Ni-SiO2 composite microspheres are attributed to a higher attenuation constant, Debye relaxation, interface polarization of the core-shell structure and synergistic effects between high dielectric loss and high magnetic loss.

  2. Effect of Critical Plasma Spray Parameters on Microstructure and Microwave Absorption Property of Ti3SiC2/Cordierite Coatings

    NASA Astrophysics Data System (ADS)

    Su, Jinbu; Zhou, Wancheng; Wang, Hongyu; Liu, Yi; Qing, Yuchang; Luo, Fa; Zhu, Dongmei; Zhou, Liang

    2016-04-01

    Ti3SiC2/cordierite coatings with different critical plasma spray parameters (CPSP) were fabricated via atmospheric plasma spraying method. The microstructure and phase constitution of the as-sprayed Ti3SiC2/cordierite coatings were characterized. The effects of CPSP conditions on the electromagnetic shielding, and dielectric and microwave absorption properties of coatings in the frequency of 8.2-12.4 GHz were also measured and investigated. The results showed that both real and imaginary part of the complex permittivity decrease with increasing CPSP values, which can be ascribed to the decomposition of some Ti3SiC2 into TiC. The calculated reflection loss of the as-sprayed Ti3SiC2/cordierite coatings with different CPSP conditions and thicknesses indicates that coatings with CPSP 0.3, 0.35, and 0.425 exhibit excellent microwave absorption property in the thickness of 1.5 mm. In order to broaden the bandwidth of the coatings, a double-layer coating system was designed. The calculated reflection loss results show that when the thickness of matching layer is 0.3 mm and the thickness of absorbing layer is 1.5 mm, the double-layer coating system shows a proper microwave absorption property with a minimum absorption value of -17.37 dB at 9.67 GHz and a absorption bandwidth (RL less than -5 dB) of 4.16 GHz in the investigated frequency.

  3. Excellent electromagnetic wave absorption property of quaternary composites consisting of reduced graphene oxide, polyaniline and FeNi3@SiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Ding, Xiao; Huang, Ying; Wang, Jianguo; Wu, Haiwei; Liu, Panbo

    2015-12-01

    The electromagnetic wave absorption properties of the quaternary composites consisting of reduced graphene oxide (rGO), polyaniline (PANI), FeNi3@SiO2 (FeNi3 nanocrystals encapsulated in SiO2) nanoparticles had never been reported. In this case, we prepared FeNi3@SiO2@rGO-PANI quaternary composites and TEM results shows spherical nanoparticles are well distributed on the surface of rGO-PANI nanosheets. The investigation of the electromagnetic wave absorbability reveals that the quaternary composites exhibit wide absorption bandwidth and enhanced electromagnetic wave absorption properties. The absorption bandwidth with reflection loss less than -10 dB (90% attenuation) is up to 6.64 GHz (10.08-10.80 GHz, 12.08-18.0 GHz), and the maximum reflection loss reaches about -40.18 dB at 14.0 GHz with the thickness of 2.4 mm. It is believed that the FeNi3@SiO2@rGO-PANI composites can serve as excellent electromagnetic wave absorbent and can be widely used in practice.

  4. Comparative absorption, electroabsorption and electrochemical studies of intervalence electron transfer and electronic coupling in cyanide-bridged bimetallic systems: ancillary ligand effects

    NASA Astrophysics Data System (ADS)

    Vance, Fredrick W.; Slone, Robert V.; Stern, Charlotte L.; Hupp, Joseph T.

    2000-03-01

    Electroabsorption or Stark spectroscopy has been used to evaluate the systems (NC) 5M II-CN-Ru III(NH 3) 51- and (NC) 5M II-CN-Ru III(NH 3) 4py 1-, where M II=Fe II or Ru II. When a pyridine ligand is present in the axial position on the Ru III acceptor, the effective optical electron transfer distance - as measured by the change in dipole moment, |Δ μ| - is increased by more than 35% relative to the ammine substituted counterpart. Comparison of the charge transfer distances to the crystal structure of Na[(CN) 5Fe-CN-Ru(NH 3) 4py] · 6H 2O reveals that the Stark derived distances are ˜50% to ˜90% of the geometric separation of the metal centers. The differences result in an upward revision in the Hush delocalization parameter, c b2, and of the electronic coupling matrix element, H ab, relative to those parameters obtained exclusively from electronic absorption measurements. The revised parameters are compared to those, which are obtained via electrochemical techniques and found to be in only fair agreement. We conclude that the absorption/electroabsorption analysis likely yields a more reliable set of mixing and coupling parameters.

  5. Surface adsorption of metals onto the earthworm Lumbricus rubellus and the isopod Porcellio scaber is negligible compared to absorption in the body.

    PubMed

    Vijver, Martina G; Wolterbeek, Hubert Th; Vink, Jos P M; van Gestel, Cornelis A M

    2005-03-20

    In terrestrial organisms, bioaccumulation is usually based on a summation of the amount of metal adsorbed to the body wall and absorbed into the body. The relative proportions of metal adsorption and absorption are usually not quantified. In this study, the distinction between adsorbed and absorbed metals was investigated in two different terrestrial species exposed to metals for 2 weeks. The earthworm Lumbricus rubellus was chosen as representative for organisms mainly taking up metals via the dermal route, and the isopod Porcellio scaber as an organism taking up metals mainly via the alimentary tract. Cross-sections of whole animals were made using a cryostat and accumulated metals were localized by means of a phosphor screen (autoradiography). Radiolabels were used to determine the distribution of metals over the different organs and to distinguish between adsorption and absorption. Cd in the earthworm was mainly found in tissues of the chloragogenous region, whereas Zn was also found in various other organs and in the connective tissue. In the isopod, both Cd and Zn were mainly located in the hepatopancreas. Adsorbed amounts of Cd and Zn were negligible compared to internalized Cd and Zn concentrations for both organisms. Consequently, when focusing on effects of metal uptake for the organism itself, there is no need to correct for adsorption. This suggests that adsorption to the epidermis is not a rate limiting step in metal uptake by soil invertebrates.

  6. Absorption properties of type-II InAs/InAsSb superlattices measured by spectroscopic ellipsometry

    SciTech Connect

    Webster, P. T.; Riordan, N. A.; Liu, S.; Zhang, Y.-H.; Johnson, S. R.; Steenbergen, E. H.

    2015-02-09

    Strain-balanced InAs/InAsSb superlattices offer access to the mid- to long-wavelength infrared region with what is essentially a ternary material system at the GaSb lattice constant. The absorption coefficients of InAs/InAsSb superlattices grown by molecular beam epitaxy on (100)-oriented GaSb substrates are measured at room temperature over the 30 to 800 meV photon energy range using spectroscopic ellipsometry, and the miniband structure of each superlattice is calculated using a Kronig-Penney model. The InAs/InAsSb conduction band offset is used as a fitting parameter to align the calculated superlattice ground state transition energy to the measured absorption onset at room temperature and to the photoluminescence peak energy at low temperature. It is observed that the ground state absorption coefficient and transition strength are proportional to the square of the wavefunction overlap and the ground state absorption coefficient approaches a maximum value of around 5780 cm{sup −1} as the wavefunction overlap approaches 100%. The absorption analysis of these samples indicates that the optical joint density of states is weakly dependent on the period thickness and Sb content of the superlattice, and that wavefunction overlap is the principal design parameter in terms of obtaining strong absorption in these structures.

  7. [Effect of Charge-Transfer Complex on Ultraviolet-Visible (UV-Vis) Absorption Property of Chromophoric Dissolved Organic Matter (CDOM) in Waters of Typical Water-Level Fluctuation Zones of the Three Gorges Reservoir Areas].

    PubMed

    Jiang, Tao; Liang, Jian; Zhang, Mu-xue; Wang, Ding-yong; Wei, Shi-qiang; Lu, Song

    2016-02-15

    As an important fraction of dissolved organic matter (DOM), chromophoric dissolved organic matter (CDOM) plays a key role in decision of the optical properties and photogeochemistry of DOM, and further affects pollutant fate and global carbon cycle. These optical properties are ascribed to two chromophoric systems including superposition of individual chromophores and charge-transfer (CT) complexation between electron donor (e.g., phenols and indoles) and acceptor (e.g., quinones and other oxidized aromatics) in DOM structures. Thus in this study, based on the "double-chromophoric system" model, DOM samples from four typical water-level fluctuation zones of Three Gorges Reservoir (TGR) areas were selected, to investigate the effect and contribution of charge-transfer complex to ultraviolet-visible (UV-Vis) absorption property of CDOM. Using NaBH, reduction method, original featureless absorption curve was classified into two independent curves caused by individual chromophoric group, which were derived from a simple superposition of independent chromophore and charge-transfer complex, respectively. Also, the changes in curve properties and specific parameters before and after NaBH4 reduction were compared. The results showed that in all DOM samples from the four sites of TGR, more than 35% of absorption was attributed from CT complex. Shibaozhai of Zhongxian and Zhenxi of Fuling showed the highest proportion ( > 50%). It suggested that the role of CT complex in CDOM property could not be neglected. After removal of CT complex, absorption curve showed blue-shift and CDOM concentration [a (355)] decreased significantly. Meanwhile, because of deforming of bonds by reduction, DOM structures became more dispersive and the molecular size was decreased, resulting in the lower spectral slope (S) observed, which evidentially supported that the supermolecular association structure of DOM was self-assembled through CT complex. Meanwhile, deceasing hydrophobic components led

  8. Modeling of gamma ray energy-absorption buildup factors for thermoluminescent dosimetric materials using multilayer perceptron neural network: A comparative study

    NASA Astrophysics Data System (ADS)

    Kucuk, Nil; Manohara, S. R.; Hanagodimath, S. M.; Gerward, L.

    2013-05-01

    In this work, multilayered perceptron neural networks (MLPNNs) were presented for the computation of the gamma-ray energy absorption buildup factors (BA) of seven thermoluminescent dosimetric (TLD) materials [LiF, BeO, Na2B4O7, CaSO4, Li2B4O7, KMgF3, Ca3(PO4)2] in the energy region 0.015-15 MeV, and for penetration depths up to 10 mfp (mean-free-path). The MLPNNs have been trained by a Levenberg-Marquardt learning algorithm. The developed model is in 99% agreement with the ANSI/ANS-6.4.3 standard data set. Furthermore, the model is fast and does not require tremendous computational efforts. The estimated BA data for TLD materials have been given with penetration depth and incident photon energy as comparative to the results of the interpolation method using the Geometrical Progression (G-P) fitting formula.

  9. The role of scattering and absorption on the optical properties of birefringent polycrystalline ceramics: Modeling and experiments on ruby (Cr:Al2O3)

    NASA Astrophysics Data System (ADS)

    Penilla, E. H.; Hardin, C. L.; Kodera, Y.; Basun, S. A.; Evans, D. R.; Garay, J. E.

    2016-01-01

    Light scattering due to birefringence has prevented the use of polycrystalline ceramics with anisotropic optical properties in applications such as laser gain media. However, continued development of processing technology has allowed for very low porosity and fine grains, significantly improving transparency and is paving the way for polycrystalline ceramics to be used in demanding optical applications. We present a method for producing highly transparent Cr3+ doped Al2O3 (ruby) using current activated pressure assisted densification. The one-step doping/densification process produces fine grained ceramics with well integrated (doped) Cr, resulting in good absorption and emission. In order to explain the light transmission properties, we extend the analytical model based on the Rayleigh-Gans-Debye approximation that has been previously used for undoped alumina to include absorption. The model presented captures reflection, scattering, and absorption phenomena in the ceramics. Comparison with measured transmission confirms that the model adequately describes the properties of polycrystalline ruby. In addition the measured emission spectra and emission lifetime are found to be similar to single crystals, confirming the high optical quality of the ceramics.

  10. A Comparative Study of Analytical and Numerical Evaluation of Elastic Properties of Short Fiber Composites

    NASA Astrophysics Data System (ADS)

    Reddy, Babu; Badari Narayana, K.

    2016-09-01

    Unlike the case of continuous fiber composites, the prediction of elastic properties of short fiber composites using the corresponding elastic properties of constituents is not a straight forward task. Many authors have attempted to predict the properties using completely either by analytical or by experimental methods or a combination of both leading to empirical solutions. The current trend is to use the well known numerical solution Finite element method (FEM) to model the short fiber composite to predict their properties. In this paper, a RVE (Representative Volume Element) approach is used to model, with appropriate boundary and loading conditions and application of homogenization process to estimate elastic properties. The present values are compared with the available experimental and analytical solutions. The methods that best match with the current FE solutions are highlighted.

  11. Facile synthesis and enhanced microwave absorption properties of novel hierarchical heterostructures based on a Ni microsphere-CuO nano-rice core-shell composite.

    PubMed

    Zhao, Biao; Shao, Gang; Fan, Bingbing; Zhao, Wanyu; Zhang, Rui

    2015-02-28

    A novel hierarchical heterostructure of Ni microspheres-CuO nano-rices was fabricated using a simple two-step process. The CuO rices were densely deposited on the surfaces of Ni microspheres. The phase purity, morphology, and structure of composite heterostructures are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). Different structured Ni-CuO composite heterostructures are also investigated by adjusting the volume ratio of the reactants. The core-shell rice-like CuO-coated Ni exhibits better antioxidation capability than pure Ni due to the presence of the barrier effect of the CuO shell, which is revealed by the thermogravimetric analysis (TGA). In comparison with pristine Ni microspheres and CuO nanoflakes, the Ni-CuO composites exhibit excellent microwave absorption properties. Moreover, the amount of CuO plays a vital role in the microwave attenuation of Ni-CuO composites. The Ni-CuO heterostructures prepared at 0.017 M Cu(2+) exhibit the best electromagnetic wave absorption capabilities. A minimum reflection loss reaches -62.2 dB (>99.9999% microwave absorption) at 13.8 GHz with the thickness of only 1.7 mm. The effective absorption (below -10 dB) bandwidth can be tuned between 6.4 GHz and 18.0 GHz by tuning the absorber thickness of 1.3-3.0 mm. Thus, the Ni-CuO composite possesses a fascinating microwave absorption performance as a novel absorbing material with strong absorption, wide-band gap and thin thickness. PMID:25639203

  12. Facile synthesis and enhanced microwave absorption properties of novel hierarchical heterostructures based on a Ni microsphere-CuO nano-rice core-shell composite.

    PubMed

    Zhao, Biao; Shao, Gang; Fan, Bingbing; Zhao, Wanyu; Zhang, Rui

    2015-02-28

    A novel hierarchical heterostructure of Ni microspheres-CuO nano-rices was fabricated using a simple two-step process. The CuO rices were densely deposited on the surfaces of Ni microspheres. The phase purity, morphology, and structure of composite heterostructures are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). Different structured Ni-CuO composite heterostructures are also investigated by adjusting the volume ratio of the reactants. The core-shell rice-like CuO-coated Ni exhibits better antioxidation capability than pure Ni due to the presence of the barrier effect of the CuO shell, which is revealed by the thermogravimetric analysis (TGA). In comparison with pristine Ni microspheres and CuO nanoflakes, the Ni-CuO composites exhibit excellent microwave absorption properties. Moreover, the amount of CuO plays a vital role in the microwave attenuation of Ni-CuO composites. The Ni-CuO heterostructures prepared at 0.017 M Cu(2+) exhibit the best electromagnetic wave absorption capabilities. A minimum reflection loss reaches -62.2 dB (>99.9999% microwave absorption) at 13.8 GHz with the thickness of only 1.7 mm. The effective absorption (below -10 dB) bandwidth can be tuned between 6.4 GHz and 18.0 GHz by tuning the absorber thickness of 1.3-3.0 mm. Thus, the Ni-CuO composite possesses a fascinating microwave absorption performance as a novel absorbing material with strong absorption, wide-band gap and thin thickness.

  13. Comparative Evaluation of the Antimicrobial Properties of Glass Ionomer Cements with and without Chlorhexidine Gluconate

    PubMed Central

    Jampanapalli, Sharada Reddy; Konda, Suhasini; Inguva, Hema Chandrika; Chimata, Vamsi Krishna

    2016-01-01

    ABSTRACT Background: Chlorhexidine gluconate is a widely used antimicrobial agent. Adding chlorhexidine and quaternary ammonium compounds to filling materials, such as composite resins, acrylic resins, and glass ionomer cements increases the antibacterial property of restorative materials. This study includes antibacterial property of glass ionomer restorative cements with chlorhexidine gluconate. Aim: The primary objective of our study was to compare the antimicrobial properties of two commercially available glass ionomer cements with and without chlorhexidine gluconate on strains of mutans streptococci. Materials and methods: Two glass ionomers (Fuji II Conventional and Fuji IX) were used. Chlorhexidine gluconate was mixed with glass ionomer cements, and antimicrobial properties against mutans streptococci were assessed by agar diffusion. The tested bacterial strain was inhibited and the antimicrobial properties decreased with time. Results: The highest amount of antimicrobial activity with mean inhibitory zone was found in Fuji II with chlorhexidine gluconate followed by Fuji IX with chlorhexidine gluconate, Fuji II without chlorhexidine gluconate, and Fuji IX without chlorhexidine gluconate. Conclusion: The results of the study confirmed that the addition of 5% chlorhexidine gluconate to Fuji II and Fuji IX glass ionomer cements resulted in a restorative material that had increased antimicrobial properties over the conventional glass ionomer cements alone for Streptococcus mutans. How to cite this article: Yadiki JV, Jampanapalli SR , Konda S, Inguva HC, Chimata VK. Comparative Evaluation of the Antimicrobial Properties of Glass Ionomer Cements with and without Chlorhexidine Gluconate. Int J Clin Pediatr Dent 2016;9(2):99-103. PMID:27365927

  14. Comparative study on the spectral properties of boron clusters Bn0/−1(n = 38–40)

    PubMed Central

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Sun, Guangyu; Qin, Shuijie

    2016-01-01

    The all-boron fullerenes B40−1 and B39−1 discovered in recent experiments are characterized and revealed using photoelectron spectroscopy. Except for the photoelectron spectroscopy, one may identify such boron clusters with other spectroscopic techniques, such as infrared spectra and Raman spectra. Insight into the spectral properties of boron clusters is important to understand the boron clusters and find their potential applications. In this work, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to comparatively study the vibrational frequencies, infrared spectra, Raman spectra and electronic absorption spectra of boron clusters Bn0/−1(n = 38–40). The numerical simulations show that such boron clusters have different and meaningful spectral features. These spectral features are readily compared with future spectroscopy measurements and can be used as fingerprints to distinguish the boron clusters Bn0/−1 with different structures (cage structure or quasi-planar structure) and with different sizes (n = 38–40). PMID:27113504

  15. Comparative study on the spectral properties of boron clusters Bn(0/-1)(n = 38-40).

    PubMed

    Li, Shixiong; Zhang, Zhengping; Long, Zhengwen; Sun, Guangyu; Qin, Shuijie

    2016-01-01

    The all-boron fullerenes B40(-1) and B39(-1) discovered in recent experiments are characterized and revealed using photoelectron spectroscopy. Except for the photoelectron spectroscopy, one may identify such boron clusters with other spectroscopic techniques, such as infrared spectra and Raman spectra. Insight into the spectral properties of boron clusters is important to understand the boron clusters and find their potential applications. In this work, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to comparatively study the vibrational frequencies, infrared spectra, Raman spectra and electronic absorption spectra of boron clusters Bn(0/-1)(n = 38-40). The numerical simulations show that such boron clusters have different and meaningful spectral features. These spectral features are readily compared with future spectroscopy measurements and can be used as fingerprints to distinguish the boron clusters Bn(0/-1) with different structures (cage structure or quasi-planar structure) and with different sizes (n = 38-40). PMID:27113504

  16. Scattering and absorption properties of near-surface aerosol over Gangetic-Himalayan region: the role of boundary layer dynamics and long-range transport

    NASA Astrophysics Data System (ADS)

    Dumka, U. C.; Kaskaoutis, D. G.; Srivastava, M. K.; Devara, P. C. S.

    2014-08-01

    Knowledge of light scattering and absorption properties of atmospheric aerosols is of vital importance in evaluating their types, sources and radiative forcing. This is of particular interest over the Gangetic-Himalayan (GH) region due to large aerosol loading over the plains and the uplift over the Himalayan range causing serious effects on atmospheric heating, glaciology and monsoon circulation. In this respect, Ganges Valley Aerosol Experiment (GVAX) was initiated over the region aiming to examine the aerosol properties, source regions, uplift mechanisms and aerosol-cloud interactions. The present study examines the temporal (monthly, seasonal) evolution of scattering (σsp) and absorption (σap) coefficients, their wavelength dependence, and the role of the Indo-Gangetic plains (IGP), boundary-layer dynamics (BLD) and long-range transport (LRT) in the aerosol uplift over the Himalayas. The measurements are performed at the elevated site Nainital via the Atmospheric Radiation Measurement Mobile Facility including several instruments (Nephelometer, Particle Soot Absorption Photometer, etc.) during June 2011 to March 2012. The σsp and σap exhibit a pronounced seasonal variation with monsoon low and post-monsoon (November) high, while the scattering wavelength exponent exhibits higher values during monsoon, in contrast to the absorption Ångström exponent which maximizes in December-March. The analysis is performed separately for particles bellow 10 and 1μm in diameter in order to examine the influence of the particle size on optical properties. The elevated-background measuring site provides the advantage of examining the LRT of natural and anthropogenic aerosols from the IGP and southwest Asia and the role of BLD in the aerosol lifting processes, while the aerosols are found to be well-mixed and aged-type dominant.

  17. Comparative toxicological and chemical properties of fuels developed from coal, shale, or petroleum

    SciTech Connect

    Guerin, M.R.; Griest, W.H.; Ho, C.H.; Smith, L.H.; Epler, J.L.; Witschi, H.R.

    1984-01-01

    Diesel fuel-, gasoline-, and heating oil-range materials prepared from coal, shale, and petroleum are found to exhibit similar toxicological properties in studies to date. Benzo(a)pyrene content, the weight distribution of bioactive chemical fractions, bacterial mutagenicity, and skin tumorigenicity are found comparable for several refined products. 15 references, 3 tables.

  18. Optical Properties of Fluorescent Mixtures: Comparing Quantum Dots to Organic Dyes

    ERIC Educational Resources Information Center

    Hutchins, Benjamin M.; Morgan, Thomas T.; Ucak-Astarlioglu, Mine G.; Wlilliams, Mary Elizabeth

    2007-01-01

    The study describes and compares the size-dependent optical properties of organic dyes with those of semiconductor nanocrystals or quantum dots (QDs). The analysis shows that mixtures of QDs contain emission colors that are sum of the individual QD components.

  19. Comparative Investigation of the Psychometric Properties of Three Tests of Logical Thinking.

    ERIC Educational Resources Information Center

    Ahlawat, Kapur S.; Billeh, Victor Y.

    1987-01-01

    Presents a comparative analysis of the psychometric properties of three group tests of logical thinking used in science education research. Findings dealing with Longeot's Test of Logical Thinking, Lawson's Test of Formal Reasoning, and Tobin and Capie's Test of Logical Thinking demonstrate a lack of concurrent validity. Includes recommendations.…

  20. Comparative study on properties of edible films based on pinhao (Araucaria angustifolia) starch and flour

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of this study was to develop and compare the properties of edible films based on pinhao starch and pinhao flour. Seven formulations were developed by casting methodology: 5% pinhao starch with 0, 1, 1.5, and 2% glycerol, and 5% pinhao flour with 1, 1.5, and 2% glycerol. The films were evalua...

  1. Facile preparation and enhanced microwave absorption properties of core-shell composite spheres composited of Ni cores and TiO2 shells.

    PubMed

    Zhao, Biao; Shao, Gang; Fan, Bingbing; Zhao, Wanyu; Xie, Yajun; Zhang, Rui

    2015-04-14

    Core-shell microspheres with Ni cores and two phases of TiO2 (anatase, rutile) shells have been successfully synthesized. The crystal structure, morphology and microwave absorption properties of the as-prepared composites were analyzed by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, and vector network analysis. The core-shell rutile TiO2-coated Ni exhibits better antioxidation ability than that of pure Ni due to the presence of the rutile TiO2 shell, which is confirmed by the thermal gravimetric analysis (TGA). In comparison with bare Ni, these two composites show better microwave absorption properties. The minimum reflection loss (RL) is -38.0 dB at 11.1 GHz with a thickness of only 1.8 mm for the Ni@TiO2 (rutile) composite. The enhanced absorption capability arises from the efficient complementarities between the magnetic loss and dielectric loss, multiple interfacial polarization, high thermal conductivity of rutile TiO2 and microwave attenuation constant. These results show that the thin high-efficiency rutile TiO2-coated Ni composite is a great potential microwave absorbing material for practical applications. PMID:25745675

  2. Enhanced Microwave Absorption Properties of Intrinsically Core/shell Structured La(0.6)Sr(0.4)MnO(3) Nanoparticles.

    PubMed

    Cheng, Y L; Dai, J M; Zhu, X B; Wu, D J; Yang, Z R; Sun, Y P

    2009-06-17

    The intrinsically core/shell structured La(0.6)Sr(0.4)MnO(3) nanoparticles with amorphous shells and ferromagnetic cores have been prepared. The magnetic, dielectric and microwave absorption properties are investigated in the frequency range from 1 to 12 GHz. An optimal reflection loss of -41.1 dB is reached at 8.2 GHz with a matching thickness of 2.2 mm, the bandwidth with a reflection loss less than -10 dB is obtained in the 5.5-11.3 GHz range for absorber thicknesses of 1.5-2.5 mm. The excellent microwave absorption properties are a consequence of the better electromagnetic matching due to the existence of the protective amorphous shells, the ferromagnetic cores, as well as the particular core/shell microstructure. As a result, the La(0.6)Sr(0.4)MnO(3) nanoparticles with amorphous shells and ferromagnetic cores may become attractive candidates for the new types of electromagnetic wave absorption materials. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11671-009-9374-y) contains supplementary material, which is available to authorized users.

  3. Comparative Study on Intersubband Absorption in AlGaN/GaN and AlInN/GaN Heterostructures Grown on Low-Defect Substrates

    NASA Astrophysics Data System (ADS)

    Edmunds, Colin; Tang, Liang; Shao, Jiayi; Li, Donghui; Gardner, Geoff; Manfra, Michael; Malis, Oana; Grier, Andrew; Ikonic, Zoran; Harrison, Paul; Zakharov, Dimitri

    2013-03-01

    Intersubband (ISB) devices utilizing III-nitrides have attracted attention for near- and far-infrared optoelectronic applications. However, the lattice mismatch between GaN and commonly used substrates results in a high defect density that hinders the vertical transport required for these devices. Furthermore, most devices in the literature utilize AlGaN/GaN heterostructures for which there is no lattice-matched alloy composition. Due to this lattice mismatch, AlGaN is not ideal for the development of complex devices such as quantum cascade lasers that often require active-region thicknesses on the order of microns for efficient operation. Fortunately, exact lattice matching occurs in AlInN/GaN heterostructures at roughly 18% In composition. To investigate the challenges of lattice-matched nitrides, we presents a comparative study of ISB absorption in high-quality AlGaN/GaN and near lattice-matched AlInN/GaN heterostructures grown by molecular-beam epitaxy on low-defect free-standing GaN substrates. Experimental measurements of transition energy, integrated absorbance and linewidth were compared to theoretical predictions that included many-body effects, interface roughness and calculations of the transition lifetime.

  4. Cirrus cloud optical and microphysical property retrievals from eMAS during SEAC4RS using bi-spectral reflectance measurements within the 1.88 µm water vapor absorption band

    NASA Astrophysics Data System (ADS)

    Meyer, Kerry; Platnick, Steven; Arnold, G. Thomas; Holz, Robert E.; Veglio, Paolo; Yorks, John; Wang, Chenxi

    2016-04-01

    Previous bi-spectral imager retrievals of cloud optical thickness (COT) and effective particle radius (CER) based on the Nakajima and King (1990) approach, such as those of the operational MODIS cloud optical property retrieval product (MOD06), have typically paired a non-absorbing visible or near-infrared wavelength, sensitive to COT, with an absorbing shortwave or mid-wave infrared wavelength sensitive to CER. However, in practice it is only necessary to select two spectral channels that exhibit a strong contrast in cloud particle absorption. Here it is shown, using eMAS observations obtained during NASA's SEAC4RS field campaign, that selecting two absorbing wavelength channels within the broader 1.88 µm water vapor absorption band, namely the 1.83 and 1.93 µm channels that have sufficient differences in ice crystal single scattering albedo, can yield COT and CER retrievals for thin to moderately thick single-layer cirrus that are reasonably consistent with other solar and IR imager-based and lidar-based retrievals. A distinct advantage of this channel selection for cirrus cloud retrievals is that the below-cloud water vapor absorption minimizes the surface contribution to measured cloudy top-of-atmosphere reflectance, in particular compared to the solar window channels used in heritage retrievals such as MOD06. This reduces retrieval uncertainty resulting from errors in the surface reflectance assumption and reduces the frequency of retrieval failures for thin cirrus clouds.

  5. Comparative Study of Magnetic Properties of Nanoparticles by High-Frequency Heat Dissipation and Conventional Magnetometry

    SciTech Connect

    Malik, V.; Goodwill, J.; Mallapragada, S.; Prozorov, T.; Prozorov, R.

    2014-11-13

    The rate of heating of a water-based colloid of uniformly sized 15 nm magnetic nanoparticles by high-amplitude and high-frequency ac magnetic field induced by the resonating LC circuit (nanoTherics Magnetherm) was measured. The results are analyzed in terms of specific energy absorption rate (SAR). Fitting field amplitude and frequency dependences of SAR to the linear response theory, magnetic moment per particles was extracted. The value of magnetic moment was independently evaluated from dc magnetization measurements (Quantum Design MPMS) of a frozen colloid by fitting field-dependent magnetization to Langevin function. The two methods produced similar results, which are compared to the theoretical expectation for this particle size. Additionally, analysis of SAR curves yielded effective relaxation time.

  6. Comparative Study of Magnetic Properties of Nanoparticles by High-Frequency Heat Dissipation and Conventional Magnetometry

    DOE PAGES

    Malik, V.; Goodwill, J.; Mallapragada, S.; Prozorov, T.; Prozorov, R.

    2014-11-13

    The rate of heating of a water-based colloid of uniformly sized 15 nm magnetic nanoparticles by high-amplitude and high-frequency ac magnetic field induced by the resonating LC circuit (nanoTherics Magnetherm) was measured. The results are analyzed in terms of specific energy absorption rate (SAR). Fitting field amplitude and frequency dependences of SAR to the linear response theory, magnetic moment per particles was extracted. The value of magnetic moment was independently evaluated from dc magnetization measurements (Quantum Design MPMS) of a frozen colloid by fitting field-dependent magnetization to Langevin function. The two methods produced similar results, which are compared to themore » theoretical expectation for this particle size. Additionally, analysis of SAR curves yielded effective relaxation time.« less

  7. Ultra-violet absorption induced modifications in bulk and nanoscale electrical transport properties of Al-doped ZnO thin films

    SciTech Connect

    Kumar, Mohit; Basu, Tanmoy; Som, Tapobrata

    2015-08-07

    Using conductive atomic force microscopy and Kelvin probe force microscopy, we study local electrical transport properties in aluminum-doped zinc oxide (ZnO:Al or AZO) thin films. Current mapping shows a spatial variation in conductivity which corroborates well with the local mapping of donor concentration (∼10{sup 20 }cm{sup −3}). In addition, a strong enhancement in the local current at grains is observed after exposing the film to ultra-violet (UV) light which is attributed to persistent photocurrent. Further, it is shown that UV absorption gives a smooth conduction in AZO film which in turn gives rise to an improvement in the bulk photoresponsivity of an n-AZO/p-Si heterojunction diode. This finding is in contrast to the belief that UV absorption in an AZO layer leads to an optical loss for the underneath absorbing layer of a heterojunction solar cell.

  8. Spectroscopic properties of Bi2ZnOB2O6 single crystals doped with Pr3+ ions: Absorption and luminescence investigations

    NASA Astrophysics Data System (ADS)

    Kasprowicz, D.; Brik, M. G.; Jaroszewski, K.; Pedzinski, T.; Bursa, B.; Głuchowski, P.; Majchrowski, A.; Michalski, E.

    2015-09-01

    Nonlinear optical Bi2ZnOB2O6 single crystals doped with Pr3+ ions were grown using the Kyropoulos method. The absorption and luminescence properties of these new systems were investigated for the first time. The crystals are characterized by the large values of nonlinear optical coefficients. Effective luminescence of the Pr3+ ions makes this system an excellent candidate for the near-infrared (NIR) and/or ultraviolet (UV) to visible (VIS) laser converters. Based on the obtained experimental spectroscopic data, detailed analysis of the absorption and luminescence spectra was performed using the conventional Judd-Ofelt theory. Those transitions, which can be potentially used for laser applications of the Pr3+ ion, have been identified. In addition to the intensity parameters Ω2, Ω4, Ω6 the branching ratios and radiative lifetimes were estimated for all possible transitions in the studied spectral region.

  9. Preparation and Absorption Spectral Property of a Multifunctional Water-Soluble Azo Compound with D-π-A Structure, 4-(4- Hydroxy-1-Naphthylazo)Benzoic Acid

    NASA Astrophysics Data System (ADS)

    Hu, L.; Lv, H.; Xie, C. G.; Chang, W. G.; Yan, Z. Q.

    2015-07-01

    A multifunctional water-soluble azo dye with the D-π-A conjugated structure, 4-(4-hydroxy-1-naphthylazo) benzoic acid ( HNBA), was designed and synthesized using 1-naphanol as the electron donator, benzoic acid as the electron acceptor, and -N=N- as the bridging group. After its structure was characterized by FTIR, 1H NMR, and element analysis, the UV-Vis absorption spectral performance of the target dye was studied in detail. The results showed that the dye, combining hydroxyl group, azo group, and carboxyl group, possessed excellent absorption spectral properties (ɛ = 1.2·104 l·mol-1·cm-1) changing with pH and solvents. In particular, in polar and protonic water, it had excellent optical response to some metal ions, i.e., Fe3+ and Pb2+, which might make it a latent colorimetric sensor for detecting heavy metal ions.

  10. Microwave absorption properties of polypyrrole-SrFe12O19-TiO2-epoxy resin nanocomposites: Optimization using response surface methodology

    NASA Astrophysics Data System (ADS)

    Seyed Dorraji, M. S.; Rasoulifard, M. H.; Amani-Ghadim, A. R.; Khodabandeloo, M. H.; Felekari, M.; Khoshrou, M. R.; hajimiri, I.

    2016-10-01

    At a few works are discussed about formation of heterogeneous composites with different distribution of particle shape and size that are used for electromagnetic absorption purposes. In this study a novel heterogeneous nanocpmposites is investigated. The nanocomposite has been successfully prepared based on epoxy resin including various nano-metal oxides (TiO2, SrFe12O19) and polypyrrole (PPy) by sol-gel and the solution chemistry method, respectively. The performance of prepared nanocomposite in absorption of microwave in X-band range was investigated and transmission line method by X-band waveguide straight was used to measure EM parameters of nanocomposites. The Response surface methodology (RSM) with central composite design (CCD) was utilized to study the effects of the wt.% TiO2 in SrFe12O19, wt.% Tio2-SrFe12O19 in PPy and wt.% TiO2-SrFe12O19-PPy in epoxy resin, on the microwave absorption properties with the absorber thickness of only 2 mm. The proposed quadratic model was in accordance with the experimental results with correlation coefficient of 96.5%. The optimum condition for maximum microwave absorption efficiency were wt.% TiO2 in SrFe12O19 of 70, wt.% TiO2-SrFe12O19 in PPy of 10 and wt.% TiO2-SrFe12O19-PPy in epoxy of 25. The sample prepared in optimal conditions indicated reflection loss of -15 dB corresponding to 97% absorption, at the range of 9.2-10.8 GHz.

  11. A comparative study of physical properties of gypsums manufactured in India.

    PubMed

    Singh, Rameshwar; Singh, Kamleshwar; Agrawal, Kaushal K

    2013-12-01

    Gypsum products are one of the most widely used materials in dentistry. The wide use of plaster of paris motivated a number of manufacturers to introduce different brands of the profession but their physical and mechanical properties were still questionable. The aim of this study was to access, compare and evaluate the physical properties of different brands of laboratory gypsum available in Indian dental market. Seven brands namely Calspar, Rajhans, Elephant, Horse, Lion, Johnson and Shree Niwas Chemicals were selected for the comparison of their particle size, consistency and setting time. The obtained data were tabulated and compared with Indian, Australian and US standard specification. Statistical analysis for comparative study was done. It was found that none of the brands were up to mark. The present study shall be able to provide some beneficial information regarding their quality control and guide the manufacturers for improving the standardization of their products so that most suitable type of material may be available to the profession.

  12. Facile synthesis of ZnFe{sub 2}O{sub 4}/reduced graphene oxide nanohybrids for enhanced microwave absorption properties

    SciTech Connect

    Yang, Zhiwei; Wan, Yizao; Xiong, Guangyao; Li, Deying; Li, Qiuping; Ma, Chunying; Guo, Ruisong; Luo, Honglin

    2015-01-15

    Highlights: • ZnFe{sub 2}O{sub 4} nanoparticles with a small diameter are uniformly anchored on RGO surface. • A strong interfacial bonding was formed between ZnFe{sub 2}O{sub 4} nanoparticles and RGO. • The minimum RL of ZnFe{sub 2}O{sub 4}/RGO nanohybrids is −29.3 dB at 16.7 GHz and 1.6 mm. • ZnFe{sub 2}O{sub 4}/RGO nanohybrids show great promise as a microwave absorption material. - Abstract: The nanohybrids composed of ZnFe{sub 2}O{sub 4} and reduced graphene oxide (RGO) have been synthesized by a facile one-step hydrothermal strategy. The morphology and structure of ZnFe{sub 2}O{sub 4}/RGO nanohybrids were characterized by transmission electron microscopy, X-ray diffraction and Raman spectra. RGO content was also determined by thermogravimetric analysis. The results confirm the formation of nanohybrids with a content of 20.4 wt% RGO and extensive interfaces between small-diameter ZnFe{sub 2}O{sub 4} nanoparticles and RGO sheets. The magnetic properties and electromagnetic parameters of ZnFe{sub 2}O{sub 4}/RGO nanohybrids were measured and the microwave absorption properties were investigated. ZnFe{sub 2}O{sub 4}/RGO nanohybrids exhibit the advantages of thin matching thickness and strong absorption at high frequency bands. It is demonstrated that ZnFe{sub 2}O{sub 4}/RGO nanohybrids can be a powerful candidate in the field of microwave absorption.

  13. Light absorption properties of water soluble organic aerosol from Residential Wood Burning in Fresno, CA: Results from 2013 NASA DISCOVER-AQ Campaign

    NASA Astrophysics Data System (ADS)

    Kim, H.; Zhang, Q.; Young, D. E.; Parworth, C.

    2015-12-01

    Light absorption properties of water soluble organic aerosol were investigated at Fresno, CA from 13 January to 11 February, 2013 as part of the NASA DISCOVER-AQ campaign. The light absorption spectra of water soluble organic aerosol in PM2.5 was measured using a UV/vis diode array detector (DAD) coupled with a particle into liquid sampler (PILS) that sampled downstream of a PM2.5 cyclone (URG). The PILS was also coupled with two ion chromatographs (IC) to measure inorganic and organic ionic species in PM2.5. In addition, an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed at the same site to measure size-resolved chemical composition of submicrometer aerosol (PM1) in real time during this study. Light absorption at 365 nm (Abs365), which is typically used as a proxy of water-soluble brown carbon (BrC), showed strong enhancement during night time and appeared to correlate well (r = 0.71) with biomass burning organic aerosol (BBOA) from residential wood burning for heating in the Fresno area. The tight correlations between Abs365 and biomass burning relevant tracers such as acetonitrile (r = 0.69), AMS-signature ions for phenolic compounds (r = 0.52-0.71), PAH (r = 0.74), and potassium (r = 0.67) further confirm that biomass burning contributed significantly to water soluble brown carbon during this study. The absorption angstrom exponent (Åa) values fitted between 300 and 700 nm wavelength were 3.3 ± 1.1, 2.0 ± 0.9 and 4.0 ± 0.8, respectively, in the morning, afternoon and nighttime, indicating that BrC is prevalent at night in Fresno during wintertime. However, there are also indications that small amount of BrC existed during the daytime as well, likely due to daytime wood burning and other sources such as the formation of light-absorbing secondary organic aerosol (SOA). Finally, light absorption at 300 nm, 330 nm, and 390 nm were found to correlate tightly with BBOA, which indicate that biomass burning also emits

  14. Comparing the estimation methods of stable distributions with respect to robustness properties

    NASA Astrophysics Data System (ADS)

    Celik, Nuri; Erden, Samet; Sarikaya, M. Zeki

    2016-04-01

    In statistical applications, some data set may exhibit the features like high skewness and kurtosis and heavy tailness that are incompatible with the normality assumption especially in finance and engineering. For these reason, the modeling of the data sets with α stable distributions will be reasonable approach. The stable distributions have four parameters. In literature, the estimation methods have been studied in order to estimate these unknown model parameters. In this study, we give small information about these proposed estimation methods and we compare these estimators with respect to robustness properties with a comprehensive simulation study, since the robustness property of an estimator has been an important tool for an appropriate modeling.

  15. Local versus global electronic properties of chalcopyrite alloys: X-ray absorption spectroscopy and ab initio calculations

    SciTech Connect

    Sarmiento-Pérez, Rafael; Botti, Silvana; Schnohr, Claudia S.; Lauermann, Iver; Rubio, Angel; Johnson, Benjamin

    2014-09-07

    Element-specific unoccupied electronic states of Cu(In, Ga)S{sub 2} were studied as a function of the In/Ga ratio by combining X-ray absorption spectroscopy with density functional theory calculations. The S absorption edge shifts with changing In/Ga ratio as expected from the variation of the band gap. In contrast, the cation edge positions are largely independent of composition despite the changing band gap. This unexpected behavior is well reproduced by our calculations and originates from the dependence of the electronic states on the local atomic environment. The changing band gap arises from a changing spatial average of these localized states with changing alloy composition.

  16. Improved microwave absorption and electromagnetic properties of BaFe{sub 12}O{sub 19}-poly(vinylidene fluoride) composites by incorporating reduced graphene oxides

    SciTech Connect

    He, Hongcai; Luo, Feifei; Qian, Neng; Wang, Ning

    2015-02-28

    Three-phase composites of poly(vinylidene fluoride)-BaFe{sub 12}O{sub 19}-reduced graphene oxide (PVDF–BFO-RGO) were synthesized by a facile wet chemical method and hot-pressing approach. The phase structure, topography of the hybrid materials were characterized by X-ray diffraction, scanning electron microscopy, and Raman spectra. Influence of RGO on their electromagnetic properties was investigated. Especially, improved microwave absorption and electromagnetic properties of BaFe{sub 12}O{sub 19}–PVDF composites by incorporating RGO were obtained and studied. The PVDF/BFO/RGO sample with m(RGO):m(BFO) = 5:100 shows the best microwave absorption properties with a minimum RL = −32 dB at 11 GHz and with the bandwidth less than −20 dB from 9.6 to 12.8 GHz. The composites were believed to have potential applications as the microwave absorber.

  17. Comparative assessment of the leprosy antibody absorption test, Mycobacterium leprae extract enzyme-linked immunosorbent assay, and gelatin particle agglutination test for serodiagnosis of lepromatous leprosy.

    PubMed Central

    Escobar-Gutiérrez, A; Amezcua, M E; Pastén, S; Pallares, F; Cázares, J V; Pulido, R M; Flores, O; Castro, E; Rodríguez, O

    1993-01-01

    A comparative assessment of three serological methods for leprosy diagnosis (the fluorescent leprosy antibody absorption [FLA-ABS] test, the Mycobacterium leprae soluble-extract enzyme-linked immunosorbent assay [ELISA], and the M. leprae particle agglutination [MLPA] test) was carried out. The objective was to identify their performance in clinical and epidemiological diagnosis of leprosy. The study group included 45 lepromatous leprosy patients under treatment. Specificity was > 95% for all three assays, and sensitivity was 95, 58, and 74% for the FLA-ABS test, the MLPA test, and the ELISA, respectively. The only cross-reactivity for M. tuberculosis-infected patients was with the soluble-extract ELISA. Although the FLA-ABS test displayed the highest specificity and sensitivity values, it can only be used in well-developed laboratories, and the patient's clinical and epidemiological background must be considered when results are interpreted because the test remains positive after therapeutic success and could be positive for some household contacts. The MLPA test is easier to perform and interpret, and it is adequate for small laboratories and epidemiological studies intended to detect active untreated or irregularly treated leprosy cases. Therefore, the FLA-ABS and MLPA tests are complementary, and both should be used for serodiagnosis of leprosy. PMID:8501238

  18. One-Pot Synthesis of (NiFe2O4)x-(SrFe12O19)1-x Nanocomposites and Their Microwave Absorption Properties.

    PubMed

    Hazra, Subhenjit; Ghosh, Barun Kumar; Patra, Manoj Kumar; Jani, Raj Kumar; Vadera, Sampat Raj; Ghosh, Narendra Nath

    2015-09-01

    In this paper, we report a simple but novel aqueous solution based 'one-pot' method for preparation of (NiFe2O4)x-(SrFe12O19)1-x nanocomposites consist of hard ferrite-soft ferrite phases. A physical mixing method has also been employed to prepare nanocomposites having same compositions. The effects of synthetic methodologies on the microstructures of the nanocomposites as well as their magnetic and microwave absorption properties have been evaluated. Crystal structures and microstructures of these composites have been investigated by using X-ray diffraction, transmission electron microscope and scanning electron microscope. In the nanocomposites, prepared by both methods, presence of nanocrystalline NiFe2O4 and SrFe12O19 phases was detected. However, nanocomposites, prepared by one-pot method, possessed better homogeneous distribution of hard and soft ferrite phases than the nanocomposites, prepared by physical mixing method. Nanocomposites, prepared by one-pot method, demonstrated significant spring exchange coupling interaction between hard and soft ferrite phases and exhibited magnetically single phase behaviour. The spring exchange coupling interaction enhanced the magnetic properties (high saturation magnetization and coercivity) and microwave absorption properties of the nanocomposites, prepared by one-pot method, in comparison with the nanocomposites prepared by physical mixing method as well as pure NiFe2O4 and SrFe12O19 nanoparticles. Minimum reflection loss of the composite was ~ -17 dB (i.e., 98% absorption) at 8.2 GHz for an absorber thickness of 3.2 mm.

  19. Fructus ligustri lucidi ethanol extract improves bone mineral density and properties through modulating calcium absorption-related gene expression in kidney and duodenum of growing rats.

    PubMed

    Feng, Xin; Lyu, Ying; Wu, Zhenghao; Fang, Yuehui; Xu, Hao; Zhao, Pengling; Xu, Yajun; Feng, Haotian

    2014-04-01

    Optimizing peak bone mass in early life is one of key preventive strategies against osteoporosis. Fructus ligustri lucidi (FLL), the fruit of Ligustrum lucidum Ait., is a commonly prescribed herb in many kidney-tonifying traditional Chinese medicinal formulas to alleviate osteoporosis. Previously, FLL extracts have been shown to have osteoprotective effect in aged or ovariectomized rats. In the present study, we investigated the effects of FLL ethanol extract on bone mineral density (BMD) and mechanical properties in growing male rats and explored the underlying mechanisms. Male weaning Sprague-Dawley rats were randomized into four groups and orally administrated for 4 months an AIN-93G formula-based diet supplementing with different doses of FLL ethanol extract (0.40, 0.65, and 0.90 %) or vehicle control, respectively. Then calcium balance, serum level of Ca, P, 25(OH)2D3, 1,25(OH)2D3, osteocalcin (OCN), C-terminal telopeptide of type I collagen (CTX-I), and parathyroid hormone, bone microarchitecture, and calcium absorption-related genes expression in duodenum and kidney were analyzed. The results demonstrated that FLL ethanol extract increased BMD of growing rats and improved their bone microarchitecture and mechanical properties. FLL ethanol extract altered bone turnover, as evidenced by increasing a bone formation maker, OCN, and decreasing a bone resorption maker, CTX-I. Intriguingly, both Ca absorption and Ca retention rate were elevated by FLL ethanol extract treatment, possibly through the mechanisms of up-regulating the transcriptions of calcitropic genes in kidney (1α-hydroxylase) and duodenum (vitamin D receptor, calcium transporter calbindin-D9k, and transient receptor potential vanilloid 6). In conclusion, FLL ethanol extract increased bone mass gain and improved bone properties via modulating bone turnover and up-regulating calcium absorption-related gene expression in kidney and duodenum, which could then activate 1,25(OH)2D3-dependent calcium

  20. Fructus ligustri lucidi ethanol extract improves bone mineral density and properties through modulating calcium absorption-related gene expression in kidney and duodenum of growing rats.

    PubMed

    Feng, Xin; Lyu, Ying; Wu, Zhenghao; Fang, Yuehui; Xu, Hao; Zhao, Pengling; Xu, Yajun; Feng, Haotian

    2014-04-01

    Optimizing peak bone mass in early life is one of key preventive strategies against osteoporosis. Fructus ligustri lucidi (FLL), the fruit of Ligustrum lucidum Ait., is a commonly prescribed herb in many kidney-tonifying traditional Chinese medicinal formulas to alleviate osteoporosis. Previously, FLL extracts have been shown to have osteoprotective effect in aged or ovariectomized rats. In the present study, we investigated the effects of FLL ethanol extract on bone mineral density (BMD) and mechanical properties in growing male rats and explored the underlying mechanisms. Male weaning Sprague-Dawley rats were randomized into four groups and orally administrated for 4 months an AIN-93G formula-based diet supplementing with different doses of FLL ethanol extract (0.40, 0.65, and 0.90 %) or vehicle control, respectively. Then calcium balance, serum level of Ca, P, 25(OH)2D3, 1,25(OH)2D3, osteocalcin (OCN), C-terminal telopeptide of type I collagen (CTX-I), and parathyroid hormone, bone microarchitecture, and calcium absorption-related genes expression in duodenum and kidney were analyzed. The results demonstrated that FLL ethanol extract increased BMD of growing rats and improved their bone microarchitecture and mechanical properties. FLL ethanol extract altered bone turnover, as evidenced by increasing a bone formation maker, OCN, and decreasing a bone resorption maker, CTX-I. Intriguingly, both Ca absorption and Ca retention rate were elevated by FLL ethanol extract treatment, possibly through the mechanisms of up-regulating the transcriptions of calcitropic genes in kidney (1α-hydroxylase) and duodenum (vitamin D receptor, calcium transporter calbindin-D9k, and transient receptor potential vanilloid 6). In conclusion, FLL ethanol extract increased bone mass gain and improved bone properties via modulating bone turnover and up-regulating calcium absorption-related gene expression in kidney and duodenum, which could then activate 1,25(OH)2D3-dependent calcium

  1. One-Pot Synthesis of (NiFe2O4)x-(SrFe12O19)1-x Nanocomposites and Their Microwave Absorption Properties.

    PubMed

    Hazra, Subhenjit; Ghosh, Barun Kumar; Patra, Manoj Kumar; Jani, Raj Kumar; Vadera, Sampat Raj; Ghosh, Narendra Nath

    2015-09-01

    In this paper, we report a simple but novel aqueous solution based 'one-pot' method for preparation of (NiFe2O4)x-(SrFe12O19)1-x nanocomposites consist of hard ferrite-soft ferrite phases. A physical mixing method has also been employed to prepare nanocomposites having same compositions. The effects of synthetic methodologies on the microstructures of the nanocomposites as well as their magnetic and microwave absorption properties have been evaluated. Crystal structures and microstructures of these composites have been investigated by using X-ray diffraction, transmission electron microscope and scanning electron microscope. In the nanocomposites, prepared by both methods, presence of nanocrystalline NiFe2O4 and SrFe12O19 phases was detected. However, nanocomposites, prepared by one-pot method, possessed better homogeneous distribution of hard and soft ferrite phases than the nanocomposites, prepared by physical mixing method. Nanocomposites, prepared by one-pot method, demonstrated significant spring exchange coupling interaction between hard and soft ferrite phases and exhibited magnetically single phase behaviour. The spring exchange coupling interaction enhanced the magnetic properties (high saturation magnetization and coercivity) and microwave absorption properties of the nanocomposites, prepared by one-pot method, in comparison with the nanocomposites prepared by physical mixing method as well as pure NiFe2O4 and SrFe12O19 nanoparticles. Minimum reflection loss of the composite was ~ -17 dB (i.e., 98% absorption) at 8.2 GHz for an absorber thickness of 3.2 mm. PMID:26716212

  2. A Comparative Study of the Physical and Mechanical Properties of Hydrogen Using Data Mining Research Techniques

    NASA Astrophysics Data System (ADS)

    Settouti, Nadera; Aourag, Hafid

    2015-09-01

    Hydrogen was the first element to exist in the universe. It is the lightest and simplest element, but chemists do not agree about its placement in the periodic table; its position has given rise to much confusion. Metallization of hydrogen under high pressure influences its properties and its placement in the periodic table. The properties of groups I, IV, and VII are investigated, and are then compared to those of hydrogen. In this study, we present a data mining approach to determine models and discover the similarities included in the datasets. Principal component analysis and partial least squares regression were applied as data analysis techniques in order to explore multivariate data. Our results indicate that hydrogen shares some properties with certain elements and groups in the periodic table, such as carbon group elements, but not entirely, because hydrogen is still considered as an element that is special and apart.

  3. DFT/TDDFT investigation on the chemical reactivities, aromatic properties, and UV-Vis absorption spectra of 1-butoxy-4-methoxybenzenepillar[5]arene constitutional isomers.

    PubMed

    Zhang, Jian; Ren, Shuqing

    2016-09-01

    We investigate the chemical reactivities, aromatic properties, and UV-Vis absorption spectra of four constitutional isomers of 1-butoxy-4-methoxybenzenepillar[5]arene with the DFT and TDDFT methods. These characteristics in the gas and solvent phases are discussed on the basis of electronic energy, the highest occupied molecular orbital energy, electrophilicity, global hardness, chemical potential, and nucleus-independent chemical shift. The out-of-plane component of the NICS values reveals that there is a great contrast between aromatic rings of the isomer and benzene. The most intense wavelengths of BMpillar[5]arenes are all made up of delocalized-delocalized π → π* transition. PMID:27535850

  4. A Comparative Study of Some Properties of Cassava and Tree Cassava Starch Films

    NASA Astrophysics Data System (ADS)

    Belibi, P. C.; Daou, T. J.; Ndjaka, J. M. B.; Nsom, B.; Michelin, L.; Durand, B.

    Cassava and tree cassava starch films plasticized with glycerol were produced by casting method. Different glycerol contents (30, 35, 40 and 45 wt. % on starch dry basis) were used and the resulting films were fully characterized. Their water barrier and mechanical properties were compared. While increasing glycerol concentration, moisture content, water solubility, water vapour permeability, tensile strength, percent elongation at break and Young's modulus decreased for both cassava and tree cassava films. Tree cassava films presented better values of water vapour permeability, water solubility and percent elongation at break compared to those of cassava films, regardless of the glycerol content.

  5. The effect of Ni pre-implantation on surface morphology and optical absorption properties of Ag nanoparticles embedded in SiO2

    NASA Astrophysics Data System (ADS)

    Shen, Yanyan; Qi, Ting; Qiao, Yu; Yu, Shengwang; Hei, Hongjun; He, Zhiyong

    2016-02-01

    The effect of Ni ion fluence on Ag nucleation and particle growth was investigated by sequentially implantation of 60 keV Ni ions at fluences of 1 × 1016, 5 × 1016, 1 × 1017 ions/cm2 and 70 keV Ag ions at a fluence of 5 × 1016 ions/cm2. Due to the modification of the deposition and accumulation process of Ag implants caused by Ni pre-implantation, the surface morphology, structures, and optical absorption properties of the Ag nanoparticles (NPs) depends strongly on the Ni fluences. UV-vis absorption spectroscopy study showed that the introducing of Ni atoms lead to intensity decrease in the Ag SPR band. Remarkable local concentration increase of Ag profiles appeared for the sample pre-implanted by Ni ions of 5.0 × 1016 ions/cm2. In particular, the AgNi alloy NPs with dual absorption peaks centered at 406 nm and 563 nm have been formed after 600 °C annealing in Ar atmosphere. However, at a low fluence of 1.0 × 1016 ions/cm2, only small increase of the local Ag concentration than the Ag ions singly implanted sample can be observed. At a high fluence of 1.0 × 1017 ions/cm2, lots Ag atoms are trapped close to the surface, which result in heavy sputtering loss of Ag atoms and the sublimation of Ag atoms after 600 °C annealing.

  6. Design, synthesis, and properties of phthalocyanine complexes with main-group elements showing main absorption and fluorescence beyond 1000 nm.

    PubMed

    Furuyama, Taniyuki; Satoh, Koh; Kushiya, Tomofumi; Kobayashi, Nagao

    2014-01-15

    We present a comprehensive description of the unique properties of newly developed phthalocyanines (Pcs) containing main-group elements that absorb and emit in the near-IR region. Group 16 (S, Se, and Te) elements and group 15 (P, As, and Sb) elements were used as peripheral and central (core) substituents. With the introduction of group 16 elements into free-base Pc, a red-shift of the Q-band was observed, as a result of the electron-donating ability of group 16 elements particularly at the α positions. An X-ray crystallographic analysis of α-ArS-, ArSe-, and ArTe-linked free-base Pcs was also successfully performed, and the relationship between structure and optical properties was clarified. When a group 15 element ion was introduced into the center of the Pc ring, the resulting Pcs showed a single Q-band peak beyond 1000 nm (up to 1056 nm in CH2Cl2). In particular, [(ArS)8PcP(OMe)2](+) and [(ArS)8PcAs(OMe)2](+) exhibited a distinct fluorescence in the 960-1400 nm region with moderate quantum yields. The atomic radius of the group 15 element is important for determining the Pc structure, so that this can be controlled by the choice of group 15 elements. Electrochemical data revealed, while MO calculations suggested, that the red-shift of the Q-band is attributable to a decrease of the HOMO-LUMO gap due to significant and moderate stabilization of the LUMO and HOMO, respectively. The effect of peripheral substutuents and a central P(V) ion on the Q-band shift was independently predicted by MO calculations, while the magnitude of the total calculated shift was in good agreement with the experimental observations. The combination of spectral, electrochemical, and theoretical considerations revealed that all of the central group 15 elements, peripheral group 16 elements, and their positions are necessary to shift the Q-band beyond 1000 nm, indicating that the substitution effects of group 15 and 16 elements act synergistically. The Pcs having Q-bands beyond 1000 nm

  7. Design, synthesis, and properties of phthalocyanine complexes with main-group elements showing main absorption and fluorescence beyond 1000 nm.

    PubMed

    Furuyama, Taniyuki; Satoh, Koh; Kushiya, Tomofumi; Kobayashi, Nagao

    2014-01-15

    We present a comprehensive description of the unique properties of newly developed phthalocyanines (Pcs) containing main-group elements that absorb and emit in the near-IR region. Group 16 (S, Se, and Te) elements and group 15 (P, As, and Sb) elements were used as peripheral and central (core) substituents. With the introduction of group 16 elements into free-base Pc, a red-shift of the Q-band was observed, as a result of the electron-donating ability of group 16 elements particularly at the α positions. An X-ray crystallographic analysis of α-ArS-, ArSe-, and ArTe-linked free-base Pcs was also successfully performed, and the relationship between structure and optical properties was clarified. When a group 15 element ion was introduced into the center of the Pc ring, the resulting Pcs showed a single Q-band peak beyond 1000 nm (up to 1056 nm in CH2Cl2). In particular, [(ArS)8PcP(OMe)2](+) and [(ArS)8PcAs(OMe)2](+) exhibited a distinct fluorescence in the 960-1400 nm region with moderate quantum yields. The atomic radius of the group 15 element is important for determining the Pc structure, so that this can be controlled by the choice of group 15 elements. Electrochemical data revealed, while MO calculations suggested, that the red-shift of the Q-band is attributable to a decrease of the HOMO-LUMO gap due to significant and moderate stabilization of the LUMO and HOMO, respectively. The effect of peripheral substutuents and a central P(V) ion on the Q-band shift was independently predicted by MO calculations, while the magnitude of the total calculated shift was in good agreement with the experimental observations. The combination of spectral, electrochemical, and theoretical considerations revealed that all of the central group 15 elements, peripheral group 16 elements, and their positions are necessary to shift the Q-band beyond 1000 nm, indicating that the substitution effects of group 15 and 16 elements act synergistically. The Pcs having Q-bands beyond 1000 nm

  8. Insect mandibles--comparative mechanical properties and links with metal incorporation.

    PubMed

    Cribb, Bronwen W; Stewart, Aaron; Huang, Han; Truss, Rowan; Noller, Barry; Rasch, Ronald; Zalucki, Myron P

    2008-01-01

    A number of arthropod taxa contain metals in their mandibles (jaws), such as zinc, manganese, iron, and calcium. The occurrence of zinc and its co-located halogen chlorine have been studied in relation to the mechanical properties and shown to be linked in a direct fashion with increasing concentration. Hardness along with elastic modulus (stiffness) has also been linked to zinc and halogen concentration in some marine polychaete worms. The metal appears to be incorporated within the biological matrix, possibly bonding with proteins. However, the comparative advantage of metal inclusion has not been tested. It is possible that without metals, alternative mechanisms are used to achieve hardness of equal value in similar 'tools' such as mandibles. This question has direct bearing on the significance of metal hardening. In the present article, we compare across mandibles from six termite species, including samples with major zinc concentration, minor manganese, and no metals. Nanoindentation, electron microscopy, and electron microanalysis are used to assess metal concentration, form, and mechanical properties. The data demonstrate that termite mandibles lacking metals when fully developed have lower values for hardness and elastic modulus. Zinc is linked to a relative 20% increase in hardness when compared with mandibles devoid of metals. The similar transition metal, manganese, found in minor concentrations, is not linked to any significant increase in these mechanical properties. This raises the question of the function of manganese, which is as commonly found in insect mandibles as zinc and often located in the same mandibles.

  9. Insect mandibles--comparative mechanical properties and links with metal incorporation.

    PubMed

    Cribb, Bronwen W; Stewart, Aaron; Huang, Han; Truss, Rowan; Noller, Barry; Rasch, Ronald; Zalucki, Myron P

    2008-01-01

    A number of arthropod taxa contain metals in their mandibles (jaws), such as zinc, manganese, iron, and calcium. The occurrence of zinc and its co-located halogen chlorine have been studied in relation to the mechanical properties and shown to be linked in a direct fashion with increasing concentration. Hardness along with elastic modulus (stiffness) has also been linked to zinc and halogen concentration in some marine polychaete worms. The metal appears to be incorporated within the biological matrix, possibly bonding with proteins. However, the comparative advantage of metal inclusion has not been tested. It is possible that without metals, alternative mechanisms are used to achieve hardness of equal value in similar 'tools' such as mandibles. This question has direct bearing on the significance of metal hardening. In the present article, we compare across mandibles from six termite species, including samples with major zinc concentration, minor manganese, and no metals. Nanoindentation, electron microscopy, and electron microanalysis are used to assess metal concentration, form, and mechanical properties. The data demonstrate that termite mandibles lacking metals when fully developed have lower values for hardness and elastic modulus. Zinc is linked to a relative 20% increase in hardness when compared with mandibles devoid of metals. The similar transition metal, manganese, found in minor concentrations, is not linked to any significant increase in these mechanical properties. This raises the question of the function of manganese, which is as commonly found in insect mandibles as zinc and often located in the same mandibles. PMID:17646951

  10. Optical properties and chemical composition of aerosol particles at an urban location: An estimation of the aerosol mass scattering and absorption efficiencies

    NASA Astrophysics Data System (ADS)

    Titos, G.; Foyo-Moreno, I.; Lyamani, H.; Querol, X.; Alastuey, A.; Alados-Arboledas, L.

    2012-02-01

    We investigated aerosol optical properties, mass concentration and chemical composition over a 1 year period (from March 2006 to February 2007) at an urban site in Southern Spain (Granada, 37.18°N, 3.58°W, 680 m above sea level). Light-scattering and absorption measurements were performed using an integrating nephelometer and a MultiAngle Absorption Photometer (MAAP), respectively, with no aerosol size cut-off and without any conditioning of the sampled air. PM10 and PM1 (ambient air levels of atmospheric particulate matter finer than 10 and 1 microns) were collected with two high volume samplers, and the chemical composition was investigated for all samples. Relative humidity (RH) within the nephelometer was below 50% and the weighting of the filters was also at RH of 50%. PM10 and PM1 mass concentrations showed a mean value of 44 ± 19 μg/m3 and 15 ± 7 μg/m3, respectively. The mineral matter was the major constituent of the PM10-1 fraction (contributing more than 58%) whereas organic matter and elemental carbon (OM+EC) contributed the most to the PM1 fraction (around 43%). The absorption coefficient at 550 nm showed a mean value of 24 ± 9 Mm-1 and the scattering coefficient at 550 nm presented a mean value of 61 ± 25 Mm-1, typical of urban areas. Both the scattering and the absorption coefficients exhibited the highest values during winter and the lowest during summer, due to the increase in the anthropogenic contribution and the lower development of the convective mixing layer during winter. A very low mean value of the single scattering albedo of 0.71 ± 0.07 at 550 nm was calculated, suggesting that urban aerosols in this site contain a large fraction of absorbing material. Mass scattering and absorption efficiencies of PM10 particles exhibited larger values during winter and lower during summer, showing a similar trend to PM1 and opposite to PM10-1. This seasonality is therefore influenced by the variations on PM composition. In addition, the mass

  11. Correlations between absorption Angström exponent (AAE) of wintertime ambient urban aerosol and its physical and chemical properties

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Filep, Á.; Pintér, M.; Török, Zs.; Bozóki, Z.; Szabó, G.

    2014-07-01

    Based on a two-week measurement campaign in an environment heavily polluted both by transit traffic and household heating in the inner city of Szeged (Hungary), correlations between the absorption Angström exponent (AAE) fitted to the optical absorption coefficients measured with a four wavelength (1064, 532, 355 and 266 nm) photoacoustic aerosol measuring system (4λ-PAS) and various aerosol parameters were identified. AAE was found to depend linearly on OCwb/EC and on NGM100/NGMD20, i.e. on the ratio of mass concentrations of elemental carbon (EC) to the fraction of organic carbon associated with wood burning (OCwb), and on the ratio of aerosol number concentrations in the 20 nm (NGMD20) to 100 nm (NGMD100) modes, with a regression coefficient of R = 0.95 and R = 0.86, respectively. In the daily fluctuation of AAE two minima were identified, which coincide with the morning and afternoon rush hours, during which NGMD20 exhibits maximum values. During the campaign the shape of the aerosol volume size distribution (dV/dlogD) was found to be largely invariant, supporting the assumption that the primary driver for the AAE variation was aerosol chemical composition rather than particle size. Furthermore, when wavelength segregated AAE values were calculated, AAE for the shorter wavelengths (AAE355-266) was also found to depend linearly on the above mentioned ratios with similar regression coefficients but with a much steeper correlation line, while the AAE for the longer wavelengths (AAE1064-532) exhibits only a considerably weaker correlation. These results prove the unique advantages of real time multi-wavelength photoacoustic measurement of optical absorption in case the wavelength range includes the ultra-violet too.

  12. Optical Absorption Spectra and Electronic Properties of Symmetric and Asymmetric Squaraine Dyes for Use in DSSC Solar Cells: DFT and TD-DFT Studies

    PubMed Central

    El-Shishtawy, Reda M.; Elroby, Shaaban A.; Asiri, Abdullah M.; Müllen, Klaus

    2016-01-01

    The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1–SQD4) were investigated using density functional theory (DFT) and time-dependent (TD-DFT) density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time dependent density functionals Perdew, Burke and Ernzerhof (PBE, PBE1PBE (PBE0)), and the exchange functional of Tao, Perdew, Staroverov, and Scuseria (TPSSh) with 6-311++G** basis set were employed to examine optical absorption properties. In an extensive comparison between the optical data and DFT benchmark calculations, the BEP functional with 6-311++G** basis set was found to be the most appropriate in describing the electronic absorption spectra. The calculated energy values of lowest unoccupied molecular orbitals (LUMO) were 3.41, 3.19, 3.38 and 3.23 eV for SQD1, SQD2, SQD3, and SQD4, respectively. These values lie above the LUMO energy (−4.26 eV) of the conduction band of TiO2 nanoparticles indicating possible electron injection from the excited dyes to the conduction band of the TiO2 in dye-sensitized solar cells (DSSCs). Also, aromaticity computation for these dyes are in good agreement with the data obtained optically and geometrically with SQD4 as the highest aromatic structure. Based on the optimized molecular geometries, relative positions of the frontier orbitals, and the absorption maxima, we propose that these dyes are suitable components of photovoltaic DSSC devices. PMID:27043556

  13. Shortwave Radiative Fluxes, Solar-Beam Transmissions, and Aerosol Properties: TARFOX and ACE-2 Find More Absorption from Flux Radiometry than from Other Measurements

    NASA Technical Reports Server (NTRS)

    Russell, Philip B.; Redemann, J.; Schmid, B.; Livingston, J. M.; Bergstrom, R. W.; Ramirez, S. A.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    The Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) and the Second Aerosol Characterization Experiment (ACE-2) made simultaneous measurements of shortwave radiative fluxes, solar-beam transmissions, and the aerosols affecting those fluxes and transmissions. Besides the measured fluxes and transmissions, other obtained properties include aerosol scattering and absorption measured in situ at the surface and aloft; aerosol single scattering albedo retrieved from skylight radiances; and aerosol complex refractive index derived by combining profiles of backscatter, extinction, and size distribution. These measurements of North Atlantic boundary layer aerosols impacted by anthropogenic pollution revealed the following characteristic results: (1) Better agreement among different types of remote measurements of aerosols (e.g., optical depth, extinction, and backscattering from sunphotometers, satellites, and lidars) than between remote and in situ measurements; 2) More extinction derived from transmission measurements than from in situ measurements; (3) Larger aerosol absorption inferred from flux radiometry than from other measurements. When the measured relationships between downwelling flux and optical depth (or beam transmission) are used to derive best-fit single scattering albedos for the polluted boundary layer aerosol, both TARFOX and ACE-2 yield midvisible values of 0.90 +/- 0.04. The other techniques give larger single scattering albedos (i.e. less absorption) for the polluted boundary layer, with a typical result of 0.95 +/- 0.04. Although the flux-based results have the virtue of describing the column aerosol unperturbed by sampling, they are subject to questions about representativeness and other uncertainties (e.g., unknown gas absorption). Current uncertainties in aerosol single scattering albedo are large in terms of climate effects. They also have an important influence on aerosol optical depths retrieved from satellite radiances

  14. An experimental study of the electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles and their electrosynthesized polymers.

    PubMed

    Diaw, A K D; Gningue-Sall, D; Yassar, A; Brochon, J-C; Henry, E; Aaron, J-J

    2015-01-25

    Electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles (N-PhPys), including HOPhPy, MeOPhPy, ThPhPy, PhDPy, DPhDPy, PyPhThThPhPy, and their available, electrosynthesized polymers were investigated. Electronic absorption spectra, fluorescence excitation and emission spectra, fluorescence quantum yields (ΦF) and lifetimes (τF), and other photophysical parameters of these N-PhPy derivatives and their polymers were measured in DMF, DMSO diluted solutions and/or solid state at room temperature. The electronic absorption spectra of N-PhPy derivatives and their polymers included one to several bands, located in the 270-395 nm region, according to the p-phenyl substituent electron-donating effect and conjugated heteroaromatic system length. The fluorescence excitation spectra were characterized by one broad main peak, with, in most cases, one (or more) poorly resolved shoulder (s), appearing in the 270-405 nm region, and their emission spectra were generally constituted of several bands located in the 330-480 nm region. No significant shift of the absorption, fluorescence excitation and emission spectra wavelengths was found upon going from the monomers to the corresponding polymers. ΦF values were high, varying between 0.11 and 0.63, according to the nature of substituents(s) and to the conjugated system extension. Fluorescence decays were mono-exponential for the monomers and poly-exponential for PyPhThThPhPy and for polymers. τF values were relatively short (0.35-5.17 ns), and markedly decreased with the electron-donor character of the phenyl group p-substituent and the conjugated system extension.

  15. Ligand-assisted fabrication of hollow CdSe nanospheres via Ostwald ripening and their microwave absorption properties.

    PubMed

    Cao, Minhua; Lian, Huiqin; Hu, Changwen

    2010-12-01

    Hollow CdSe nanospheres were successfully synthesized by a ligand-assisted solvothermal method based on an Ostwald ripening mechanism. The hollow CdSe nanospheres were synthesized in benzyl alcohol under solvothermal conditions using Cd(Ac)2 and Se as the precursors, and tryptophan as a ligand. The resulting hollow structures consisted of small nanocrystallite building blocks. More importantly, the hollow CdSe nanospheres could be used as an excellent microwave absorber for cm- and mm-wave absorption, depending on the thickness of the absorber.

  16. Wavelength-Dependent Optical Absorption Properties of Artificial and Atmospheric Aerosol Measured by a Multi-Wavelength Photoacoustic Spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Bozóki, Z.; Szabó, G.

    2014-12-01

    Various aspects of the photoacoustic (PA) detection method are discussed from the point of view of developing it into a routine tool for measuring the wavelength-dependent optical absorption coefficient of artificial and atmospheric aerosol. The discussion includes the issues of calibration, cross-sensitivity to gaseous molecules, background PA signal subtraction, and size-dependent particle losses within the PA system. The results in this paper are based on a recently developed four-wavelength PA system, which has operational wavelengths in the near-infrared, in the visible, and in the ultraviolet. The measured spectra of artificial and atmospheric aerosol prove the outstanding applicability of the presented PA system.

  17. Ultrasonication assisted preparation of carbonaceous nanoparticles modified polyurethane foam with good conductivity and high oil absorption properties

    NASA Astrophysics Data System (ADS)

    Shi, Hengchong; Shi, Dean; Yin, Ligang; Yang, Zhihua; Luan, Shifang; Gao, Jiefeng; Zha, Junwei; Yin, Jinghua; Li, Robert K. Y.

    2014-10-01

    In this work, we report a facile, low cost and time-saving method for the fabrication of compressible, electrically conductive, oil absorptive, cost-effective and flexible polyurethane (PU) foam through ultrasonication induced carbonaceous nanoparticles (CNP) onto flexible PU foam (CNP-PU foam). SEM images showed that the CNP could be firmly anchored onto the PU foam, and made the PU foam surface much rougher. Zero-dimensional carbonaceous nanoparticles were easier to anchor onto the PU foam surface than one-dimensional nanoparticles (e.g., carbon nanotube) or two-dimensional nanoparticles (e.g., graphene oxide). The CNP-PU foam exhibited excellent elasticity and high mechanical durability even when it was subjected to 500 cyclic compression. The CNP-PU foam had excellent absorption of organic solvents up to 121 times the weight of the initial PU foam. In addition, the electrical conductivity of PU foams was considerably increased with the anchoring of CNP onto the matrix. In addition, compression experiments confirmed that the electrical conductivity of CNP-PU foams changed with their compression ratios, thus exhibiting excellent pressure sensitivity. The as-prepared materials have significant potential as oil absorbents, elastic conductors, flexible electrodes, pressure sensors, etc.In this work, we report a facile, low cost and time-saving method for the fabrication of compressible, electrically conductive, oil absorptive, cost-effective and flexible polyurethane (PU) foam through ultrasonication induced carbonaceous nanoparticles (CNP) onto flexible PU foam (CNP-PU foam). SEM images showed that the CNP could be firmly anchored onto the PU foam, and made the PU foam surface much rougher. Zero-dimensional carbonaceous nanoparticles were easier to anchor onto the PU foam surface than one-dimensional nanoparticles (e.g., carbon nanotube) or two-dimensional nanoparticles (e.g., graphene oxide). The CNP-PU foam exhibited excellent elasticity and high mechanical

  18. Multifunctional polymethylsilsesquioxane (PMSQ) surfaces prepared by electrospinning at the sol-gel transition: superhydrophobicity, excellent solvent resistance, thermal stability and enhanced sound absorption property.

    PubMed

    Xiang, Haifan; Zhang, Liang; Wang, Zhen; Yu, Xiaolan; Long, Yuhua; Zhang, Xiaoli; Zhao, Ning; Xu, Jian

    2011-07-01

    Multifunctional superhydrophobic polymethylsilsesquioxane (PMSQ) surfaces with excellent solvent resistance, thermal stability and enhanced sound absorption property were manufactured by electrospinning. The surfaces with various hierarchical morphologies and hydrophobicity were obtained by electrospinning at the different stages of sol-gel transition of PMSQ prepolymer solution. At the stage with a proper viscosity the superhydrophobic PMSQ surface with a contact angle as high as 151° and a sliding angle as low as 8° was prepared. Due to the excellent thermal stability and solvent resistance properties of the cured PMSQ, the resultant surfaces remain superhydrophobicity after thermal treatment at 300 °C and immersion into many solvents. Additionally, an enhanced acoustical performance and ultra water repellency were obtained simultaneously when the traditional acoustical sponge was decorated with the electrospun PMSQ superhydrophobic surface. The robust superhydrophobic PMSQ surfaces may promise practical applications in many fields.

  19. Flavonoid interactions during digestion, absorption, distribution and metabolism: a sequential structure-activity/property relationship-based approach in the study of bioavailability and bioactivity.

    PubMed

    Gonzales, Gerard Bryan; Smagghe, Guy; Grootaert, Charlotte; Zotti, Moises; Raes, Katleen; Van Camp, John

    2015-05-01

    Flavonoids are a group of polyphenols that provide health-promoting benefits upon consumption. However, poor bioavailability has been a major hurdle in their use as drugs or nutraceuticals. Low bioavailability has been associated with flavonoid interactions at various stages of the digestion, absorption and distribution process, which is strongly affected by their molecular structure. In this review, we use structure-activity/property relationship to discuss various flavonoid interactions with food matrices, digestive enzymes, intestinal transporters and blood proteins. This approach reveals specific bioactive properties of flavonoids in the gastrointestinal tract as well as various barriers for their bioavailability. In the last part of this review, we use these insights to determine the effect of different structural characteristics on the overall bioavailability of flavonoids. Such information is crucial when flavonoid or flavonoid derivatives are used as active ingredients in foods or drugs. PMID:25633078

  20. Role of incoherent pumping field on absorption-dispersion properties of probe pulse in a graphene nanostructure under external magnetic field

    NASA Astrophysics Data System (ADS)

    Asadpour, Seyyed Hossein; Hamedi, H. R.; Soleimani, H. Rahimpour

    2015-07-01

    The optical properties of weak probe light based on quantum coherence and interference in Landau-quantized graphene nanostructure driven by two coherent fields and incoherent pumping field is investigated. The linear dynamical properties of the graphene by means of density matrix method and perturbation theory are discussed. It is found that under certain condition and for appropriate choosing the parameters of the medium, the absorption, dispersion, group index of the weak probe light can be controlled. Moreover, it is shown that by means of incoherent pumping field the superluminal light propagation in the system is accompanied by amplification to make sure that the probe field is amplified as it passes through the system. Moreover, it is observed that the probe amplification can be obtained in the presence or absence of population inversion by properly choosing of system's parameters. We hope that these results may have useful in the future quantum communicational system and networks.

  1. Optical diffusion property of cerumen from ear canal and correlation to metal content measured by synchrotron x-ray absorption

    NASA Astrophysics Data System (ADS)

    Holden, Todd; Dehipawala, Sumudu; Cheung, E.; Golebiewska, U.; Schneider, P.; Tremberger, G., Jr.; Kokkinos, D.; Lieberman, D.; Dehipawala, Sunil; Cheung, T.

    2012-03-01

    Human (and other mammals) would secrete cerumen (ear wax) to protect the skin of the ear canal against pathogens and insects. The studies of biodiversity of pathogen in human include intestine microbe colony, belly button microbe colony, etc. Metals such as zinc and iron are essentials to bio-molecular pathways and would be related to the underlying pathogen vitality. This project studies the biodiversity of cerumen via its metal content and aims to develop an optical probe for metal content characterization. The optical diffusion mean free path and absorption of human cerumen samples dissolved in solvent have been measured in standard transmission measurements. EXFAS and XANES have been measured at Brookhaven Synchrotron Light Source for the determination of metal contents, presumably embedded within microbes/insects/skin cells. The results show that a calibration procedure can be used to correlate the optical diffusion parameters to the metal content, thus expanding the diagnostic of cerumen in the study of human pathogen biodiversity without the regular use of a synchrotron light source. Although biodiversity measurements would not be seriously affected by dead microbes and absorption based method would do well, the scattering mean free path method would have potential to further study the cell based scattering centers (dead or live) via the information embedded in the speckle pattern in the deep-Fresnel zone.

  2. Absorption and photoluminescence properties of Er-doped and Er/Yb codoped soda-silicate laser glasses

    SciTech Connect

    Li, S.F.; Zhang, Q.Y.; Lee, Y.P.

    2004-11-01

    Er-doped and Er/Yb codoped soda-silicate laser glasses with various concentrations of Er and Yb were fabricated. The absorption and the photoluminescence (PL) spectra were measured and analyzed. For the Er- doped soda-slilicate glasses, the optimum Er concentration for the PL intensity at 1536 nm turns out to be 0.5 at. %, and the full width at half maximum (FWHM) of PL spectrum increases from 18 to 26 nm, with the increase of the concentration from 0.1 to 0.8 at. %. The PL intensity of Er/Yb codoped soda-silicate glasses with an Er concentration of 0.5 at. % is enhanced approximately by four times, and the optimum Yb concentration for the PL intensity at 1536 nm is analyzed to be 3.0 at. %. The PL spectrum becomes broader with increasing the Yb concentration, up to a FWHM of 80 nm at 6.0 at. %. Yb. The relation between the absorption and PL spectra, together with the mechanism of PL broadening, has also been addressed.

  3. Physical properties of the interstellar medium using high-resolution Chandra spectra: O K-edge absorption

    SciTech Connect

    Gatuzz, E.; Mendoza, C.; García, J.; Kallman, T. R.; Bautista, M. A.; Gorczyca, T. W. E-mail: claudio@ivic.gob.ve E-mail: manuel.bautista@wmich.edu E-mail: timothy.r.kallman@nasa.gov

    2014-08-01

    Chandra high-resolution spectra toward eight low-mass Galactic binaries have been analyzed with a photoionization model that is capable of determining the physical state of the interstellar medium. Particular attention is given to the accuracy of the atomic data. Hydrogen column densities are derived with a broadband fit that takes into account pileup effects, and in general are in good agreement with previous results. The dominant features in the oxygen-edge region are O I and O II Kα absorption lines whose simultaneous fits lead to average values of the ionization parameter of log ξ = –2.90 and oxygen abundance of A{sub O} = 0.70. The latter is given relative to the standard by Grevesse and Sauval, but rescaling with the revision by Asplund et al. would lead to an average abundance value fairly close to solar. The low average oxygen column density (N{sub O} = 9.2 × 10{sup 17} cm{sup –2}) suggests a correlation with the low ionization parameters, the latter also being in evidence in the column density ratios N(O II)/N(O I) and N(O III)/N(O I) that are estimated to be less than 0.1. We do not find conclusive evidence for absorption by any other compound but atomic oxygen in our oxygen-edge region analysis.

  4. Enhanced Microwave Absorption Properties of Flexible Polymer Composite Based on Hexagonal NiCo2O4 Microplates and PVDF

    NASA Astrophysics Data System (ADS)

    Luo, Hui; Wang, Xian; Song, Kai; Yang, Jing; Gong, Rongzhou

    2016-08-01

    Hexagonal NiCo2O4 microplates were synthesized via a facile one-pot hydrothermal method and followed by a subsequent annealing process. The complex permittivity and permeability of a NiCo2O4 and polyvinylidene fluoride (PVDF) composite were investigated over 2-18 GHz. The experiment indicated that the good microwave absorption performance of NiCo2O4@PVDF depends on dielectric loss and quarter-wavelength cancellation. Our results show that the absorption frequency bandwidth of reflection loss (RL) less than -20 dB for the NiCo2O4@PVDF composite can be measured over the frequency range of 3-15.5 GHz with an absorbing thickness that varies in the range of 1.25-5 mm. Furthermore, an optimal RL of -44.8 dB was observed at 10.7 GHz with a thickness of 1.75 mm. The loss mechanism is also discussed.

  5. Joint reconstruction of absorption and refractive properties in propagation-based x-ray phase-contrast tomography via a non-linear image reconstruction algorithm

    NASA Astrophysics Data System (ADS)

    Chen, Yujia; Wang, Kun; Gursoy, Doga; Soriano, Carmen; De Carlo, Francesco; Anastasio, Mark A.

    2016-03-01

    Propagation-based X-ray phase-contrast tomography (XPCT) provides the opportunity to image weakly absorbing objects and is being explored actively for a variety of important pre-clinical applications. Quantitative XPCT image reconstruction methods typically involve a phase retrieval step followed by application of an image reconstruction algorithm. Most approaches to phase retrieval require either acquiring multiple images at different object-to-detector distances or introducing simplifying assumptions, such as a single-material assumption, to linearize the imaging model. In order to overcome these limitations, a non-linear image reconstruction method has been proposed previously that jointly estimates the absorption and refractive properties of an object from XPCT projection data acquired at a single propagation distance, without the need to linearize the imaging model. However, the numerical properties of the associated non-convex optimization problem remain largely unexplored. In this study, computer simulations are conducted to investigate the feasibility of the joint reconstruction problem in practice. We demonstrate that the joint reconstruction problem is ill-posed and sensitive to system inconsistencies. Particularly, the method can generate accurate refractive index images only if the object is thin and has no phase-wrapping in the data. However, we also observed that, for weakly absorbing objects, the refractive index images reconstructed by the joint reconstruction method are, in general, more accurate than those reconstructed using methods that simply ignore the object's absorption.

  6. Blue copper proteins: a comparative analysis of their molecular interaction properties.

    PubMed Central

    De Rienzo, F.; Gabdoulline, R. R.; Menziani, M. C.; Wade, R. C.

    2000-01-01

    Blue copper proteins are type-I copper-containing redox proteins whose role is to shuttle electrons from an electron donor to an electron acceptor in bacteria and plants. A large amount of experimental data is available on blue copper proteins; however, their functional characterization is hindered by the complexity of redox processes in biological systems. We describe here the application of a semiquantitative method based on a comparative analysis of molecular interaction fields to gain insights into the recognition properties of blue copper proteins. Molecular electrostatic and hydrophobic potentials were computed and compared for a set of 33 experimentally-determined structures of proteins from seven blue copper subfamilies, and the results were quantified by means of similarity indices. The analysis provides a classification of the blue copper proteins and shows that (I) comparison of the molecular electrostatic potentials provides useful information complementary to that highlighted by sequence analysis; (2) similarities in recognition properties can be detected for proteins belonging to different subfamilies, such as amicyanins and pseudoazurins, that may be isofunctional proteins; (3) dissimilarities in interaction properties, consistent with experimentally different binding specificities, may be observed between proteins belonging to the same subfamily, such as cyanobacterial and eukaryotic plastocyanins; (4) proteins with low sequence identity, such as azurins and pseudoazurins, can have sufficient similarity to bind to similar electron donors and acceptors while having different binding specificity profiles. PMID:10975566

  7. Comparative studies on the physicochemical and antioxidant properties of different tea extracts.

    PubMed

    Chen, Haixia; Zhang, Yu; Lu, Xueming; Qu, Zhishuang

    2012-06-01

    Tea is one of the most popular drinks next to water. Tea polyphenol is one of the main bioactive constituents of tea with health functions. In order to find the most bioactive tea polyphynols, polyphenol extracts from green tea, black tea and chemical oxidation products of green tea extracts were comparatively studied on the physicochemical and antioxidant properties. Results showed physicochemical and antioxidant properties of polyphenol extracts changed greatly after the chemical oxidation. Hydrogen peroxide induced oxidation products (HOP) possessed the highest antioxidant ability among the four tea polyphenol extracts. Thirteen phenolic compounds and one alkaloid in HOP were identified by reversed phase high-performance liquid chromatography coupled to diode array detection and electrospray ionization mass spectrometry (RP-HPLC-DAD-ESI-MS). Hydrogen peroxide induced oxidation of tea polyphenol extracts could improve the antioxidant activity and could be used to produce antioxidants for food industry. PMID:23729856

  8. UV-visible and infrared absorption spectra of gamma irradiated CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses: A comparative study

    NASA Astrophysics Data System (ADS)

    ElBatal, H. A.; Abdelghany, A. M.; ElBatal, F. H.; ElBadry, Kh. M.; Moustaffa, F. A.

    2011-10-01

    Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV bands due to combined absorption of trace iron impurities and divalent lead ions. The CuO-doped glasses reveal an extra broad visible band due to Cu 2+ ions in octahedral coordination. The effects of gamma irradiation have been analyzed for both the sharing of all constituent components including trace iron impurities. Infrared absorption spectra of the prepared samples were investigated by the KBr disk technique. The FTIR spectra reveal main characteristic absorption bands due to different phosphate groups. The IR spectra are observed to be slightly affected by the increase of CuO in the doping level (0.2-3%) indicating the stability of the main network units.

  9. Comparative study of metal and non-metal ion implantation in polymers: Optical and electrical properties

    NASA Astrophysics Data System (ADS)

    Resta, V.; Quarta, G.; Farella, I.; Maruccio, L.; Cola, A.; Calcagnile, L.

    2014-07-01

    The implantation of 1 MeV metal (63Cu+, 107Ag+, 197Au+) and non-metal (4He+, 12C+) ions in a polycarbonate (PC) matrix has been studied in order to evaluate the role of ion species in the modification of optical and electrical properties of the polymer. When the ion fluence is above ∼1 × 1013 ions cm-2, the threshold for latent tracks overlapping is overcome and π-bonded carbon clusters grow and aggregate forming a network of conjugated Cdbnd C bonds. For fluences around 1 × 1017 ions cm-2, the aggregation phenomena induce the formation of amorphous carbon and/or graphite like structures. At the same time, nucleation of metal nanoparticles (NPs) from implanted species can take place when the supersaturation threshold is overcome. The optical absorption of the samples increases in the visible range and the optical band gap redshifts from 3.40 eV up to 0.70 eV mostly due to the carbonization process and the formation of C0x clusters and cluster aggregates. Specific structures in the extinction spectra are observed when metal ions are selected in contrast to the non-metal ion implanted PC, thus revealing the possible presence of noble metal based NPs interstitial to the C0x cluster network. The corresponding electrical resistance decreases much more when metal ions are implanted with at least a factor of 2 orders of magnitude difference than the non-metal ions based samples. An absolute value of ∼107 Ω/sq has been measured for implantation with metals at doses higher than 5 × 1016 ions cm-2, being 1017 Ω/sq the corresponding sheet resistance for pristine PC.

  10. A Comparative Analysis of Antimicrobial Property of Wine and Ozone with Calcium Hydroxide and Chlorhexidine

    PubMed Central

    Ebenezar, A. V. Rajesh; Anand, Nirupa; Mary, A.Vinita; Mony, Bejoy

    2015-01-01

    Background The antibacterial properties of wine and ozone have been established but their antibacterial efficacies against endodontic pathogens are yet to be ascertained. Aim The purpose of this study is to comparatively evaluate the antibacterial property of ozonated water, white wine (14%) and de-alcoholised white wine. Materials and Methods S.mutans and E.faecalis were subcultured and inoculated in a nutrient broth for 24 hours. The following groups were formulated: Group 1A:2% Chlorhexidine (Control group); Group 1B:White wine; Group 1C:Dealcoholised white wine; Group 1D:Ozonated water; Group 2A: Ca(OH)2 + Chlorhexidine (Control group); Group 2B: White wine + Ca(OH)2; Group 2C:De-alcoholised White wine + Ca(OH)2 + chlorhexidine; Group 2D:White wine + Ca(OH)2 + chlorhexidine and group 2E: Dealcoholised white wine + Ca(OH)2 + chlorhexidine. The samples were allowed to diffuse into the culture medium for two hours, later the S. mutans were streaked on to the blood agar medium and the E. faecalis were streaked on to the Muller Hilton agar medium and incubated for 48 hours at 370C the zone of inhibition was measured after 48 hours. Results There was no growth of microorganisms seen with ozonated water. Chlorhexidine showed large zone of inhibition compared to the other groups. White wine has better antimicrobial property than de-alcoholised white wine, but when mixed with calcium hydroxide the dealcoholised white wine has better action against the microorganisms. Conclusion Ozonated water has the best antibacterial property and the antibacterial action of Calcium hydroxide is enhanced when it is mixed with de-alcoholised white wine. PMID:26266206

  11. Membrane properties of Enchytraeus albidus originating from contrasting environments: a comparative analysis.

    PubMed

    Fisker, Karina Vincents; Bouvrais, Hélène; Overgaard, Johannes; Schöttner, Konrad; Ipsen, John H; Holmstrup, Martin

    2015-05-01

    Ectothermic animals adapted to different environmental temperatures are hypothesized to have biological membranes with different chemical and physical properties such that membrane properties are optimized for their particular thermal environments. To test this hypothesis we analyzed the composition of phospholipid fatty acids (PLFAs) in seven different populations of Enchytraeus albidus originating from different thermal environments. The seven populations differ markedly in origin (polar-temperate) and are also characterized by marked difference in cold tolerance. The dominant PLFAs of E. albidus were C20:5, C20:4 and C20:2 (53-61% of total PLFA) followed by C18:0, C20:1 and C22:2 (17-20% of total PLFA). As hypothesized the PLFA composition varied significantly between populations and molar percentage of several of the PLFAs (particularly C18:2) correlated with the lower lethal temperature (LT50) of the seven populations. Unsaturation ratio (UFA/SFA) and average PLFA chain length also correlated significantly with LT50, such that cold sensitive populations had a shorter chain length and a lower UFA/SFA compared to cold tolerant populations. Reconstituted membranes of the least and most cold tolerant populations were used to compare membranes' physical properties by fluorescence anisotropy and bending rigidity. Measurements of anisotropy did not show any overall difference between populations with different cold tolerance. This could be interpreted as if E. albidus populations have achieved a similar "optimal" fluidity of the membrane with a somewhat different PLFA composition. Our study suggests that membrane lipid composition could be important for the cold tolerance of E. albidus; however, these differences are not easily differentiated in the measurements of the membranes' physical properties. Other parameters such as accumulation of glucose for cryoprotection and energy supply may also be important components of enchytraeid freeze tolerance. PMID:25663468

  12. A comparative study of physical properties of gypsums manufactured in India.

    PubMed

    Singh, Rameshwar; Singh, Kamleshwar; Agrawal, Kaushal K

    2013-12-01

    Gypsum products are one of the most widely used materials in dentistry. The wide use of plaster of paris motivated a number of manufacturers to introduce different brands of the profession but their physical and mechanical properties were still questionable. The aim of this study was to access, compare and evaluate the physical properties of different brands of laboratory gypsum available in Indian dental market. Seven brands namely Calspar, Rajhans, Elephant, Horse, Lion, Johnson and Shree Niwas Chemicals were selected for the comparison of their particle size, consistency and setting time. The obtained data were tabulated and compared with Indian, Australian and US standard specification. Statistical analysis for comparative study was done. It was found that none of the brands were up to mark. The present study shall be able to provide some beneficial information regarding their quality control and guide the manufacturers for improving the standardization of their products so that most suitable type of material may be available to the profession. PMID:24431787

  13. A comparative study on properties of micro and nanopapers produced from cellulose and cellulose nanofibres.

    PubMed

    Mtibe, A; Linganiso, Linda Z; Mathew, Aji P; Oksman, K; John, Maya J; Anandjiwala, Rajesh D

    2015-03-15

    Cellulose nanocrystals (CNCs) and cellulose nanofibres (CNFs) were successfully extracted from cellulose obtained from maize stalk residues. A variety of techniques, such as Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used for characterization and the experimental results showed that lignin and hemicellulose were removed to a greater extent by following the chemical methods. Atomic force microscopy (AFM) results confirmed that the diameters of CNCs and CNFs were ranging from 3 to 7 nm and 4 to 10nm, respectively, with their lengths in micro scale. CNCs suspension showed a flow of birefringence, however, the same was not observed in the case of suspension containing CNFs. XRD analysis confirmed that CNCs had high crystallinity index in comparison to cellulose and CNFs. Nanopapers were prepared from CNCs and CNFs by solvent evaporation method. Micropapers were also prepared from cellulose pulp by the same technique. Nanopapers made from CNFs showed less transparency as compared to nanopapers produced from CNCs whereas high transparency as compared to micropaper. Nanopapers produced from CNFs provided superior mechanical properties as compared to both micropaper and nanopapers produced from CNCs. Also, nanopapers produced from CNFs were thermally more stable as compared to nanopapers produced from CNCs but thermally less stable as compared to micropapers. PMID:25542099

  14. Novel zinc(II)phthalocyanines bearing azo-containing schiff base: Determination of pKa values, absorption, emission, enzyme inhibition and photochemical properties

    NASA Astrophysics Data System (ADS)

    Kantar, Cihan; Mavi, Vildan; Baltaş, Nimet; İslamoğlu, Fatih; Şaşmaz, Selami

    2016-10-01

    Azo-containing schiff bases are well known and there are many studies about their various properties in literature. However, phthalocyanines bearing azo-containing schiff bases, their spectral, analytical and biological properties are unknown. Therefore, new zinc (II) phthalocyanines bearing azo-containing schiff base were synthesized and investigated to determine pKa values, absorption, emission, enzyme inhibition and photochemical properties. Emission spectra were reported and large Stokes shift values were determined for all compounds, indicating that all molecules exhibit excited state intramolecular proton transfer. These phthalocyanines were the first examples of phthalocyanine showing excited state intramolecular proton transfer. Singlet oxygen quantum yields of zinc (II) phthalocyanines were determined. pKa values and indicator properties of all compounds were investigated by potentiometry. All compounds were assayed for inhibitory activity against bovine milk xanthine oxidase and acetylcholinesterase enzyme in vitro. Compound 2 showed the high inhibitory effect against xanthine oxidase (IC50 = 0.24 ± 0.01 μM). However, phthalocyanine compounds did not show enzyme inhibitor behavior.

  15. Electrical and optical properties of reduced graphene oxide and multi-walled carbon nanotubes based nanocomposites: A comparative study

    NASA Astrophysics Data System (ADS)

    Goumri, Meryem; Lucas, Bruno; Ratier, Bernard; Baitoul, Mimouna

    2016-10-01

    Graphene and multi-walled carbon nanotubes have attracted interest for a number of potential applications. One of the most actively pursued applications uses graphene and carbon nanotubes as a transparent conducting electrode in solar cells, displays or touch screens. In this work, in situ reduced graphene oxide/Poly (vinyl alcohol) and multi-walled carbon nanotubes/Sodium Dodecyl Sulfate/Poly (vinyl alcohol) composites were prepared by water dispersion and different reduction treatments. Comparative studies were conducted to explore the electrical and optical properties of nanocomposites based on graphene and multi-walled carbon nanotubes. A thermal reduction of graphene oxide was more effective, producing films with sheet resistances as low as 102-103 Ω/square with 80% transmittance for 550 nm light. The percolation threshold of the thermally reduced graphene oxide composites (0.35 vol%) was much lower than that of the chemically reduced graphene oxide composites (0.57 vol%), and than that of the carbon nanotubes composites (0.47 vol%). The Seebeck coefficient of graphene oxide films changes from about 40 μV/K to -30 μV/K after an annealing of three hours at 200 °C. The optical absorption of the nanocomposites showed a high absorbance in near UV regions and the photoluminescence enhancement was achieved at 1 wt% graphene loading, while the carbon nanotubes based composite presents a significant emission at 0.7 wt% followed with a photoluminescence quenching at higher fraction of the nanofillers 1.6 wt% TRGO and 1 wt% MWCNTs.

  16. Comparative study of mechanical properties of direct core build-up materials

    PubMed Central

    Kumar, Girish; Shivrayan, Amit

    2015-01-01

    Background and Objectives: The strength greatly influences the selection of core material because core must withstand forces due to mastication and para-function for many years. This study was conducted to evaluate certain mechanical properties of commonly used materials for direct core build-up, including visible light cured composite, polyacid modified composite, resin modified glass ionomer, high copper amalgam, and silver cermet cement. Materials and Methods: All the materials were manipulated according to the manufacturer's recommendations and standard test specimens were prepared. A universal testing machine at different cross-head speed was used to determine all the four mechanical properties. Mean compressive strength, diametral tensile strength, flexural strength, and elastic modulus with standard deviations were calculated. Multiple comparisons of the materials were also done. Results: Considerable differences in compressive strength, diametral tensile strength, and flexural strength were observed. Visible light cured composite showed relatively high compressive strength, diametral tensile strength, and flexural strength compared with the other tested materials. Amalgam showed the highest value for elastic modulus. Silver cermet showed less value for all the properties except for elastic modulus. Conclusions: Strength is one of the most important criteria for selection of a core material. Stronger materials better resist deformation and fracture provide more equitable stress distribution, greater stability, and greater probability of clinical success. PMID:25684905

  17. Comparative first-principles study of clean-surface properties of metals

    NASA Astrophysics Data System (ADS)

    Patra, Abhirup; Sun, Jianwei; Perdew, John P.

    Metal surfaces are widely used in different applications from nano-devices to heterogeneous catalysis. Clean-surface properties such as the surface energy, work function and interlayer spacing importantly determine the behavior of metal surfaces. Prior work has been done to understand these properties using high-level methods including the local density approximation (LDA) and the generalized gradient approximation (PBE). In this work, we study (111) (100) and (110) surfaces of Pt, Pd, Cu, Al, Au, Ag, Rh and Ru by extrapolation from a finite number of layers. These surfaces are studied using SCAN, a new member of the computationally-efficient meta-GGA family of density functionals. We have compared the performance of SCAN and three other standard density functionals - LDA, PBE and PBEsol - to available experimental results. We find that the performance of the general-purpose SCAN is at the level of the more-specialized PBEsol, giving accurate metallic properties. Ref: Jianwei Sun, Adrienn Ruzsinszky, John P Perdew, Strongly Constrained and Appropriately Normed Semilocal Density Functional, Physical Review Letters115 (3), 036402 (2015). Supported by NSF under DMR-1305135, CNS-09-5884, and by DOE under DE-SC0012575, DE-AC02-05CH11231.

  18. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  19. Evolution of linear absorption and nonlinear optical properties in V-shaped ruthenium(II)-based chromophores.

    PubMed

    Coe, Benjamin J; Foxon, Simon P; Harper, Elizabeth C; Helliwell, Madeleine; Raftery, James; Swanson, Catherine A; Brunschwig, Bruce S; Clays, Koen; Franz, Edith; Garín, Javier; Orduna, Jesús; Horton, Peter N; Hursthouse, Michael B

    2010-02-10

    In this article, we describe a series of complexes with electron-rich cis-{Ru(II)(NH(3))(4)}(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845-4859). They have been isolated as their PF(6)(-) salts and characterized by using various techniques including (1)H NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru(III/II) waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities beta have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d --> pi* metal-to-ligand charge-transfer (MLCT) and pi --> pi* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant beta(0) responses as high as ca. 600 x 10(-30) esu. These pseudo-C(2v) chromophores show two substantial components of the beta tensor, beta(zzz) and beta(zyy), although the relative significance of these varies with the physical method applied. According to HRS, beta(zzz) dominates in all cases, whereas the Stark analyses indicate that beta(zyy) is dominant in the shorter chromophores, but beta(zzz) and beta(zyy) are similar for the extended species. In contrast, finite field calculations predict that beta(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand pi-systems are extended. Such unusual

  20. Absorption and fluorescence properties of chromophoric dissolved organic matter: implications for the monitoring of water quality in a large subtropical reservoir.

    PubMed

    Liu, Xiaohan; Zhang, Yunlin; Shi, Kun; Zhu, Guangwei; Xu, Hai; Zhu, Mengyuan

    2014-12-01

    The development of techniques for real-time monitoring of water quality is of great importance for effectively managing inland water resources. In this study, we first analyzed the absorption and fluorescence properties in a large subtropical reservoir and then used a chromophoric dissolved organic matter (CDOM) fluorescence monitoring sensor to predict several water quality parameters including the total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), dissolved organic carbon (DOC), and CDOM fluorescence parallel factor analysis (PARAFAC) components in the reservoir. The CDOM absorption coefficient at 254 nm (a(254)), the humic-like component (C1), and the tryptophan-like component (C3) decreased significantly along a gradient from the northwest to the lake center, northeast, southwest, and southeast region in the reservoir. However, no significant spatial difference was found for the tyrosine-like component (C2), which contributed only four marked peaks. A highly significant linear correlation was found between the a(254) and CDOM concentration measured using the CDOM fluorescence sensor (r(2) = 0.865, n = 76, p < 0.001), indicating that CDOM concentrations could act as a proxy for the CDOM absorption coefficient measured in the laboratory. Significant correlations were also found between the CDOM concentration and TN, TP, COD, DOC, and the maximum fluorescence intensity of C1, suggesting that the real-time monitoring of CDOM concentrations could be used to predict these water quality parameters and trace the humic-like fluorescence substance in clear aquatic ecosystems with DOC <2 mg/L and total suspended matter (TSM) concentrations <15 mg/L. These results demonstrate that the CDOM fluorescence sensor is a useful tool for on-line water quality monitoring if the empirical relationship between the CDOM concentration measured using the CDOM fluorescence sensor and the water quality parameters is calibrated and validated.

  1. A comparative analysis of the statistical properties of large mobile phone calling networks.

    PubMed

    Li, Ming-Xia; Jiang, Zhi-Qiang; Xie, Wen-Jie; Miccichè, Salvatore; Tumminello, Michele; Zhou, Wei-Xing; Mantegna, Rosario N

    2014-05-30

    Mobile phone calling is one of the most widely used communication methods in modern society. The records of calls among mobile phone users provide us a valuable proxy for the understanding of human communication patterns embedded in social networks. Mobile phone users call each other forming a directed calling network. If only reciprocal calls are considered, we obtain an undirected mutual calling network. The preferential communication behavior between two connected users can be statistically tested and it results in two Bonferroni networks with statistically validated edges. We perform a comparative analysis of the statistical properties of these four networks, which are constructed from the calling records of more than nine million individuals in Shanghai over a period of 110 days. We find that these networks share many common structural properties and also exhibit idiosyncratic features when compared with previously studied large mobile calling networks. The empirical findings provide us an intriguing picture of a representative large social network that might shed new lights on the modelling of large social networks.

  2. A comparative analysis of the statistical properties of large mobile phone calling networks

    NASA Astrophysics Data System (ADS)

    Li, Ming-Xia; Jiang, Zhi-Qiang; Xie, Wen-Jie; Miccichè, Salvatore; Tumminello, Michele; Zhou, Wei-Xing; Mantegna, Rosario N.

    2014-05-01

    Mobile phone calling is one of the most widely used communication methods in modern society. The records of calls among mobile phone users provide us a valuable proxy for the understanding of human communication patterns embedded in social networks. Mobile phone users call each other forming a directed calling network. If only reciprocal calls are considered, we obtain an undirected mutual calling network. The preferential communication behavior between two connected users can be statistically tested and it results in two Bonferroni networks with statistically validated edges. We perform a comparative analysis of the statistical properties of these four networks, which are constructed from the calling records of more than nine million individuals in Shanghai over a period of 110 days. We find that these networks share many common structural properties and also exhibit idiosyncratic features when compared with previously studied large mobile calling networks. The empirical findings provide us an intriguing picture of a representative large social network that might shed new lights on the modelling of large social networks.

  3. Comparative Analysis of Selected Physicochemical Properties of Pozzolan Portland and MTA-Based Cements

    PubMed Central

    Dorileo, Maura Cristiane Gonçales Orçati; Villa, Ricardo Dalla; Guedes, Orlando Aguirre; Aranha, Andreza Maria Fábio; Semenoff-Segundo, Alex; Bandeca, Matheus Coelho; Borges, Alvaro Henrique

    2014-01-01

    Physicochemical properties of pozzolan Portland cement were compared to ProRoot MTA and MTA BIO. To test the pH, the samples were immersed in distilled water for different periods of time. After the pH analysis, the sample was retained in the plastic recipient, and the electrical conductivity of the solution was measured. The solubility and radiopacity properties were evaluated according to specification 57 of the American National Standard Institute/American Dental Association (ANSI/ADA). The statistical analyses were performed using ANOVA and Tukey's test at a 5% level of significance. Pozzolan Portland cement exhibited pH and electrical conductivity mean values similar to those of the MTA-based cements. The solubilities of all tested materials were in accordance with the ANSI/ADA standards. Only the MTA-based cements met the ANSI/ADA recommendations for radiopacity. It might be concluded that the pH and electrical conductivity of pozzolan Portland cement are similar to and comparable to those of MTA-based cements. PMID:27437473

  4. Comparative Analysis of Selected Physicochemical Properties of Pozzolan Portland and MTA-Based Cements.

    PubMed

    Dorileo, Maura Cristiane Gonçales Orçati; Villa, Ricardo Dalla; Guedes, Orlando Aguirre; Aranha, Andreza Maria Fábio; Semenoff-Segundo, Alex; Bandeca, Matheus Coelho; Borges, Alvaro Henrique

    2014-01-01

    Physicochemical properties of pozzolan Portland cement were compared to ProRoot MTA and MTA BIO. To test the pH, the samples were immersed in distilled water for different periods of time. After the pH analysis, the sample was retained in the plastic recipient, and the electrical conductivity of the solution was measured. The solubility and radiopacity properties were evaluated according to specification 57 of the American National Standard Institute/American Dental Association (ANSI/ADA). The statistical analyses were performed using ANOVA and Tukey's test at a 5% level of significance. Pozzolan Portland cement exhibited pH and electrical conductivity mean values similar to those of the MTA-based cements. The solubilities of all tested materials were in accordance with the ANSI/ADA standards. Only the MTA-based cements met the ANSI/ADA recommendations for radiopacity. It might be concluded that the pH and electrical conductivity of pozzolan Portland cement are similar to and comparable to those of MTA-based cements.

  5. Properties of cast films from hemp (Cannabis sativa L.) and soy protein isolates. A comparative study.

    PubMed

    Yin, Shou-Wei; Tang, Chuan-He; Wen, Qi-Biao; Yang, Xiao-Quan

    2007-09-01

    The properties of cast films from hemp protein isolate (HPI) including moisture content (MC) and total soluble mass (TSM), tensile strength (TS) and elongation at the break (EAB), and surface hydrophobicity were investigated and compared to those from soy protein isolate (SPI). The plasticizer (glycerol) level effect on these properties and the interactive force pattern for the film network formation were also evaluated. At some specific glycerol levels, HPI films had similar MC, much less TSM and EAB, and higher TS and surface hydrophobicity (support matrix side), as compared to SPI films. The TS of HPI and SPI films as a function of plasticizer level (in the range of 0.3-0.6 g/g of protein) were well fitted with the exponential equation with coefficient factors of 0.991 and 0.969, respectively. Unexpectedly, the surface hydrophobicity of HPI films (including air and support matrix sides) increased with increasing the glycerol level (from 0.3 to 0.6 g/g of protein). The analyses of protein solubility of film in various solvents and free sulfydryl group content showed that the disulfide bonds are the prominent interactive force in the HPI film network formation, while in the SPI case, besides the disulfide bonds, hydrogen bonds and hydrophobic interactions are also to a similar extent involved. The results suggest that hemp protein isolates have good potential to be applied to prepare protein film with some superior characteristics, e.g., low solubility and high surface hydrophobicity.

  6. Scattering and absorption property database for nonspherical ice particles in the near- through far-infrared spectral region.

    PubMed

    Yang, Ping; Wei, Heli; Huang, Hung-Lung; Baum, Bryan A; Hu, Yong X; Kattawar, George W; Mishchenko, Michael I; Fu, Qiang

    2005-09-10

    The single-scattering properties of ice particles in the near- through far-infrared spectral region are computed from a composite method that is based on a combination of the finite-difference time-domain technique, the T-matrix method, an improved geometrical-optics method, and Lorenz-Mie theory. Seven nonspherical ice crystal habits (aggregates, hexagonal solid and hollow columns, hexagonal plates, bullet rosettes, spheroids, and droxtals) are considered. A database of the single-scattering properties for each of these ice particles has been developed at 49 wavelengths between 3 and 100 microm and for particle sizes ranging from 2 to 10,000 microm specified in terms of the particle maximum dimension. The spectral variations of the single-scattering properties are discussed, as well as their dependence on the particle maximum dimension and effective particle size. The comparisons show that the assumption of spherical ice particles in the near-IR through far-IR region is generally not optimal for radiative transfer computation. Furthermore, a parameterization of the bulk optical properties is developed for mid-latitude cirrus clouds based on a set of 21 particle size distributions obtained from various field campaigns.

  7. Synthesis and selective IR absorption properties of iminodiacetic-acid intercalated MgAl-layered double hydroxide

    SciTech Connect

    Wang Lijing; Xu Xiangyu; Evans, David G.; Duan Xue; Li Dianqing

    2010-05-15

    An MgAl-NO{sub 3}-layered double hydroxide (LDH) precursor has been prepared by a method involving separate nucleation and aging steps (SNAS). Reaction with iminodiacetic acid (IDA) under weakly acidic conditions led to the replacement of the interlayer nitrate anions by iminodiacetic acid anions. The product was characterized by XRD, FT-IR, TG-DTA, ICP, elemental analysis and SEM. The results show that the original interlayer nitrate anions of LDHs precursor were replaced by iminodiacetic acid anions and that the resulting intercalation product MgAl-IDA-LDH has an ordered crystalline structure. MgAl-IDA-LDH was mixed with low density polyethylene (LDPE) using a masterbatch method. LDPE films filled with MgAl-IDA-LDH showed a higher mid to far infrared absorption than films filled with MgAl-CO{sub 3}-LDH in the 7-25 {mu}m range, particularly in the key 9-11 {mu}m range required for application in agricultural plastic films. - Graphical abstract: Intercalation of iminodiacetic acid (IDA) anions in a MgAl-NO{sub 3}-layered double hydroxide host leads to an enhancement of its infrared absorbing ability for application in agricultural plastic films.

  8. Comparison of the magnetic properties of GeMn thin films through Mn L-edge x-ray absorption

    SciTech Connect

    Ahlers, S.; Stone, P.R.; Sircar, N.; Arenholz, E.; Dubon, O. D.; Bougeard, D.

    2009-08-04

    X-ray absorption spectroscopy of epitaxial GeMn thin films reveals an experimentally indistinguishable electronic configuration of Mn atoms incorporated in Ge{sub 1?x}Mn{sub x} nanoclusters and in precipitates of the intermetallic compound Mn{sub 5}Ge{sub 3}, respectively. However, the average magnetic response of thin films containing Ge{sub 1?x}Mn{sub x} nanoclusters is lower than the response of films containing Mn{sub 5}Ge{sub 3} precipitates. This reduced magnetic response of Ge{sub 1?x}Mn{sub x} nanoclusters is explained in terms of a fraction of Mn atoms being magnetically inactive due to antiferromagnetic coupling or the presence of structural disorder. A determination of the role of magnetically inactive Mn atoms in the self-assembly of the thermodynamically metastable Ge{sub 1?x}Mn{sub x} nanoclusters seems to be an essential ingredient for an enhanced control of this promising high Curie temperature magnetic semiconductor.

  9. Lanthanum and Neodymium Doped Barium Ferrite-TiO2/MCNTs/poly(3-methyl thiophene) Composites with Nest Structures: Preparation, Characterization and Electromagnetic Microwave Absorption Properties

    PubMed Central

    Zhao, Jie; Yu, Jian; Xie, Yu; Le, Zhanggao; Hong, Xiaowei; Ci, Suqin; Chen, Junhong; Qing, Xiaoyan; Xie, Weijie; Wen, Zhenhai

    2016-01-01

    We report herein the synthesis of a novel nest structured electromagnetic composite through in-situ chemical polymerization of 3-methyl thiophene (3MT) in the presence of the BaFe11.92(LaNd)0.04O19-TiO2 (BFTO) nanoparticles and MCNTs. As an absorbing material, the BFTO/MCNTs/P3MT/wax composites were prepared at various loadings of BFTO/MCNTs/P3MT (0.2:0.10:1.0 ~ 0.2:0.30:1.0), and they exhibited strong microwave absorption properties in the range of 1.0–18 GHz. When the loading of BFTO/MCNTs/P3MT is 0.2:0.30:1.0, the composite has a strongest absorbing peak at 11.04 GHz, and achieves a maximum absorbing value of −21.56 dB. The absorbing peak position moves to higher frequencies with the increase of MCNTs content. The mechanism for microwave absorption of these composites has been explained in detail. PMID:26857939

  10. Analytical modeling and experimental investigation on optical properties of new class of nanofluids (Al2O3-CuO binary nanofluids) for direct absorption solar thermal energy

    NASA Astrophysics Data System (ADS)

    Menbari, Amir; Alemrajabi, Ali Akbar

    2016-02-01

    Nanofluids play a major role in many modern engineering processes. Binary nanofluids are a new class of nanofluids that are prepared by dispersing simultaneously two dissimilar nanoparticles in a base fluid. They offer a good potential for use in direct absorption solar systems. The present study investigates both experimentally and analytically the optical properties of binary nanofluids for direct absorption in solar applications. For this purpose, two dissimilar nanoparticles, i.e. CuO and γ-Al2O3, are dispersed in water, ethylene glycol, and the ethylene glycol-water mixture to form binary nanofluids. In addition, a new method is developed for calculating the extinction coefficient of the binary nanofluids based on the classical electromagnetic theory. It will be shown that the extinction coefficients obtained from both analytical and experimental studies are in good agreement. Moreover, the extinction coefficient of the binary nanofluids is found to be approximately equal to the sum of the extinction coefficients of the constituent components, determined both analytically and experimentally. By increasing the nanoparticle volume fraction, improvements are observed in the extinction coefficient of the binary nanofluids prepared. Also, the analytical and experimental results of the study show that the extinction coefficient of the binary nanoparticles dispersed in water as the "base fluid" is greater than those of the binary nanoparticles dispersed in ethylene glycol or the mixture of ethylene glycol-water.

  11. Two-photon absorption properties of cationic 1,4-bis(styryl)benzene derivative and its inclusion complexes with cyclodextrins.

    PubMed

    Nag, Okhil Kumar; Nayak, Rati Ranjan; Lim, Chang Su; Kim, In Hong; Kyhm, Kwangseuk; Cho, Bong Rae; Woo, Han Young

    2010-07-29

    Two-photon absorption properties of 1,4-bis{4'-[N,N-bis(6''-trimethylammoniumhexyl)amino]styryl}benzene tetrabromide (C1) and its inclusion complexes (ICs) with cyclodextrins (CDs) have been studied. Upon complexation with CDs, the absorption spectra of C1 showed a slight red shift, whereas the emission spectra showed a blue shift with concomitant increase in the fluorescence quantum efficiency. A Stern-Volmer study using K(3)Fe(CN)(6) as a quencher revealed significant reduction in the photoinduced charge transfer quenching, in accord with the IC formation. Comparison of the spectroscopic results reveals that C1 forms increasingly more stable ICs in the order C1/beta-CD < C1/gamma-CD < C1/(3gamma:beta)-CD (gamma-CD/beta-CD 3:1, mole ratio). Moreover, the two-photon action cross section of C1 increased from 200 GM for C1 to 400 GM for C1/beta-CD, 460 GM for C1/gamma-CD, and 650 GM for C1/(3gamma:beta)-CD, respectively. Furthermore, the two-photon microscopy images of HeLa cells stained with C1 emitted strong two-photon excited fluorescence in the plasma membrane. These results provide a useful guideline for the development of efficient two-photon materials for bioimaging applications.

  12. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Tunable Anisotropic Absorption of Ag-Embedded SiO2 Thin Films by Oblique Angle Deposition

    NASA Astrophysics Data System (ADS)

    Xiao, Xiu-Di; Dong, Guo-Ping; Shao, Jian-Da; Fan, Zheng-Xiu; He, Hong-Bo; Qi, Hong-Ji

    2009-08-01

    Ag-embedded SiO2 thin films are prepared by oblique angle deposition. Through field emission scanning electron microscopy (SEM), an orientated slanted columnar structure is observed. Energy-dispersive x-ray (EDX) analysis shows the Ag concentration is about 3% in the anisotropic SiO2 matrix. Anisotropic surface plasma resonance (SPR) absorption is observed in the Ag-embedded SiO2 thin films, which is dependent on polarization state and incidence angle of two orthogonal polarized lights and the deposition angle. This means that optical properties and anisotropic SPR absorption can be tunable in Ag-embedded SiO2 thin films. Broadband polarization splitting is also observed and the transmission ratio Tp/Ts between p- and s-polarized lights is up to 2.7 for thin films deposited at α = 70°, which means that Ag-embedded SiO2 thin films are a promising candidate for thin film polarizers.

  13. Lanthanum and Neodymium Doped Barium Ferrite-TiO₂/MCNTs/poly(3-methyl thiophene) Composites with Nest Structures: Preparation, Characterization and Electromagnetic Microwave Absorption