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Sample records for absorption enhancing agents

  1. Nasal absorption of interferon: Enhancement by surfactant agents

    SciTech Connect

    Baglioni, C.; Phipps, R.J. )

    1990-10-01

    The effect of spraying the nasal mucosa with an aerosol of recombinant human interferon-alpha (IFN-alpha 2a) was studied in an animal model, the sheep, because cultures of sheep cells were found to be responsive to the antiviral activity of this IFN. Binding assays with {sup 125}I-labeled IFN-alpha 2a detected very few receptors in sheep nasal mucosa, but a membrane fraction prepared from this mucosa had abundant high-affinity receptors. Nasal mucosa homogenates were prepared from the turbinates of sheep that had been sprayed with IFN-alpha 2a aerosols, and the 2',5'-oligoadenylate (2-5A) activity induced in response was measured. To try to enhance the permeability of the mucosa, surfactant agents were added to the IFN and aerosols generated. There were measurable levels of 2-5A synthetase after aerosols with added sodium deoxycholate or, better, polyoxyethylene 9-lauryl ether. This latter surfactant was well tolerated in previous studies with intranasally administered insulin. The level of 2-5A synthetase induced was related to the dose of IFN, and the increased activity persisted up to 72 h after an IFN aerosol. These studies suggest that surfactant agents may make IFN aerosols much more effective for the prophylaxis of respiratory virus infections.

  2. Enhancement of intestinal absorption of poorly absorbed hydrophilic compounds by simultaneous use of mucolytic agent and non-ionic surfactant.

    PubMed

    Takatsuka, Shinya; Kitazawa, Takeo; Morita, Takahiro; Horikiri, Yuji; Yoshino, Hiroyuki

    2006-01-01

    The effect of co-administration of a mucolytic agent with a penetration enhancer was assessed on the intestinal absorption of poorly absorbed hydrophilic compounds. Fluorescein isothiocyanate-labeled dextran with average molecular weight of ca. 4.4 kDa (FD-4) was used as a model compound, and N-acetylcysteine (NAC) was used as a mucolytic agent. Sodium caprate (C10), tartaric acid (TA), sodium taurodeoxycholate (TDC), sodium dodecyl sulfate (SDS), p-t-octyl phenol polyoxyethylene-9.5 (Triton X-100, TX-100) were selected as penetration enhancers with different mechanisms of action. Various dosing solutions containing a penetration enhancer in the absence or in the presence of NAC were directly administered into the exposed rat jejunum, and the bioavailability of FD-4 up to 2 h was determined. The extent of improvement by co-administration was highly dependent on the penetration enhancer species applied. The observed enhancement was thought to result from the mucolytic activity of NAC, which can reduce the mucus viscosity and facilitate the penetration of FD-4 to mucosal membrane. Among the combinations tested, the simultaneous administration of NAC and TX-100 provided the highest enhancement (22.5-fold) of intestinal FD-4 absorption compared to the control. Although the detailed mechanism for the observed drastic improvement is unclear, one possible reason was thought to be due to the improved diffusivity of TX-100 micellar system in the mucus layer. All these results suggest that the combination of a mucolytic agent and a non-ionic surfactant may have potential as an enhancing system for peroral delivery of poorly absorbed hydrophilic compounds like protein and peptide drugs.

  3. Photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1985-01-01

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  4. Enhanced absorption cycle computer model

    NASA Astrophysics Data System (ADS)

    Grossman, G.; Wilk, M.

    1993-09-01

    Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperature boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorption systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system's components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H2O triple-effect cycles, LiCl-H2O solar-powered open absorption cycles, and NH3-H2O single-effect and generator-absorber heat exchange cycles. An appendix contains the user's manual.

  5. Quantum-enhanced absorption refrigerators

    PubMed Central

    Correa, Luis A.; Palao, José P.; Alonso, Daniel; Adesso, Gerardo

    2014-01-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators. PMID:24492860

  6. Quantum-enhanced absorption refrigerators

    NASA Astrophysics Data System (ADS)

    Correa, Luis A.; Palao, José P.; Alonso, Daniel; Adesso, Gerardo

    2014-02-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators.

  7. Lactose enhances mineral absorption in infancy.

    PubMed

    Ziegler, E E; Fomon, S J

    1983-05-01

    To determine if lactose promotes the intestinal absorption of calcium and other minerals by infants, metabolic balance studies were performed with infants fed two formulas nearly identical in composition except for carbohydrate. One contained only lactose and the other contained sucrose and corn starch hydrolysate. Each of six normal infants had two balance studies performed with each formula in alternating sequence. When lactose was the carbohydrate, net absorption and net retention of calcium were significantly greater than when lactose was not present in the formula. Absorptions of magnesium and manganese were also significantly enhanced by lactose. Absorptions of copper and zinc were somewhat greater (not statistically significant) when lactose was present, whereas absorption of iron was not affected. Absorption of phosphorus was not different, but urinary excretion was less when the lactose containing formula was fed and, hence, net retention of phosphorus was significantly enhanced. These results confirm findings from animal studies and previous human studies and show that, in infants, lactose has a significant and sustained promoting effect on absorption of calcium and other minerals.

  8. Enhanced absorption cycle computer model. Final report

    SciTech Connect

    Grossman, G.; Wilk, M.

    1993-09-01

    Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperatures boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorptions systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system`s components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H{sub 2}O triple-effect cycles, LiCl-H{sub 2}O solar-powered open absorption cycles, and NH{sub 3}-H{sub 2}O single-effect and generator-absorber heat exchange cycles. An appendix contains the User`s Manual.

  9. Cavity Enhanced Ultrafast Transient Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Allison, Thomas K.; Reber, Melanie Roberts; Chen, Yuning

    2015-06-01

    Ultrafast spectroscopy on gas phase systems is typically restricted to techniques involving photoionization, whereas solution phase experiments utilize the detection of light. At Stony Brook, we are developing new techniques for performing femtosecond time-resolved spectroscopy using frequency combs and high-finesse optical resonators. A large detection sensitivity enhancement over traditional methods enables the extension of all-optical ultrafast spectroscopies, such as broad-band transient absorption spectroscopy (TAS) and 2D spectroscopy, to dilute gas phase samples produced in molecular beams. Here, gas phase data can be directly compared to solution phase data. Initial demonstration experiments are focusing on the photodissociation of iodine in small neutral argon clusters, where cluster size strongly influences the effects solvent-caging and geminate recombination. I will discuss these initial results, our high power home-built Yb:fiber laser systems, and also extensions of the methods to the mid-IR to study the vibrational dynamics of hydrogen bonded clusters.

  10. Atmospheric Measurements by Cavity Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yi, Hongming; Wu, Tao; Coeur-Tourneur, Cécile; Fertein, Eric; Gao, Xiaoming; Zhao, Weixiong; Zhang, Weijun; Chen, Weidong

    2015-04-01

    Since the last decade, atmospheric environmental monitoring has benefited from the development of novel spectroscopic measurement techniques owing to the significant breakthroughs in photonic technology from the UV to the infrared spectral domain [1]. In this presentation, we will overview our recent development and applications of cavity enhanced absorption spectroscopy techniques for in situ optical monitoring of chemically reactive atmospheric species (such as HONO, NO3, NO2, N2O5) in intensive campaigns [2] and/or in smog chamber studies [3]. These field deployments demonstrated that modern photonic technologies (newly emergent light sources combined with high sensitivity spectroscopic techniques) can provide a useful tool to improve our understanding of tropospheric chemical processes which affect climate, air quality, and the spread of pollution. Experimental detail and preliminary results will be presented. Acknowledgements. The financial support from the French Agence Nationale de la Recherche (ANR) under the NexCILAS (ANR-11-NS09-0002) and the CaPPA (ANR-10-LABX-005) contracts is acknowledged. References [1] X. Cui, C. Lengignon, T. Wu, W. Zhao, G. Wysocki, E. Fertein, C. Coeur, A. Cassez,L. Croisé, W. Chen, et al., "Photonic Sensing of the Atmosphere by absorption spectroscopy", J. Quant. Spectrosc. Rad. Transfer 113 (2012) 1300-1316 [2] T. Wu, Q. Zha, W. Chen, Z. XU, T. Wang, X. He, "Development and deployment of a cavity enhanced UV-LED spectrometer for measurements of atmospheric HONO and NO2 in Hong Kong", Atmos. Environ. 95 (2014) 544-551 [3] T. Wu, C. Coeur-Tourneur, G. Dhont,A. Cassez, E. Fertein, X. He, W. Chen,"Application of IBBCEAS to kinetic study of NO3 radical formation from O3 + NO2 reaction in an atmospheric simulation chamber", J. Quant. Spectrosc. Rad. Transfer 133 (2014)199-205

  11. Enhanced insulin absorption from sublingual microemulsions: effect of permeation enhancers.

    PubMed

    Patil, Nilam H; Devarajan, Padma V

    2014-12-01

    Microemulsions of insulin (50 IU/mL) comprising permeation enhancers were formulated for sublingual delivery. Circular dichroism (CD) spectra indicated conformational stability, while chemical stability was confirmed by high-performance liquid chromatography (HPLC). CD spectra of insulin in combination with permeation enhancers revealed attenuation of molar ellipticity at 274 nm in the order TCTP > TC-AOT > TC > TC-NMT > Sol P > insulin solution. The molar ellipticity ratios at 208/222 nm confirmed dissociation of insulin in the microemulsions with the same rank order. Matrix-assisted laser diffraction ionization mass spectra (MALDI) revealed a significant shift in intensity signals towards monomer and dimers with a substantially high ratio of monomers, especially in the presence of the TCTP and TC-AOT. Permeation through porcine sublingual mucosa correlated with the dissociation data. A high correlation between the ratio of molar ellipticity at 208/222 nm and serum glucose levels (r (2) > 0.958) and serum insulin levels (r (2) > 0.952) strongly suggests the role of dissociation of insulin on enhanced absorption. While all microemulsions revealed a reduction in serum glucose levels and increase in serum insulin levels, significant differences were observed with the TCTP and TC-AOT microemulsions. High pharmacological availability >60 % and bioavailability >55 % compared to subcutaneous insulin at a low dose of 2 IU/kg appears highly promising. The data clearly suggests the additional role of the permeation enhancers on dissociation of insulin on enhanced sublingual absorption from the microemulsions.

  12. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes

    PubMed Central

    2015-01-01

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process. PMID:26120588

  13. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes.

    PubMed

    Friese, Daniel H; Bast, Radovan; Ruud, Kenneth

    2015-05-20

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process.

  14. Studies of cavity enhanced absorption spectroscopy for weak absorption gas measurements

    NASA Astrophysics Data System (ADS)

    Li, Liucheng; Duo, Liping; Gong, Deyu; Ma, Yanhua; Zhang, Zhiguo; Wang, Yuanhu; Zhou, Dongjian; Jin, Yuqi

    2017-01-01

    In order to determine the concentrations of trace amount metastable species in chemical lasers, an off-axis cavity enhanced absorption spectrometer for the detection of weak absorption gases has been built with a noise equivalent absorption sensitivity of 1.6x10-8 cm-1. The absorption spectrum of trace amount gaseous ammonia and water vapor was obtained with a spectral resolution of about 78 MHz. A multiple-line absorption spectroscopic method to determine the temperature of gaseous ammonia has been developed by use of multiple lines of ammonia molecule absorption spectrum.

  15. Contrast agent enhanced pQCT of articular cartilage

    NASA Astrophysics Data System (ADS)

    Kallioniemi, A. S.; Jurvelin, J. S.; Nieminen, M. T.; Lammi, M. J.; Töyräs, J.

    2007-02-01

    The delayed gadolinium enhanced MRI of cartilage (dGEMRIC) technique is the only non-invasive means to estimate proteoglycan (PG) content in articular cartilage. In dGEMRIC, the anionic paramagnetic contrast agent gadopentetate distributes in inverse relation to negatively charged PGs, leading to a linear relation between T1,Gd and spatial PG content in tissue. In the present study, for the first time, contrast agent enhanced peripheral quantitative computed tomography (pQCT) was applied, analogously to dGEMRIC, for the quantitative detection of spatial PG content in cartilage. The suitability of two anionic radiographic contrast agents, gadopentetate and ioxaglate, to detect enzymatically induced PG depletion in articular cartilage was investigated. First, the interrelationships of x-ray absorption, as measured with pQCT, and the contrast agent solution concentration were investigated. Optimal contrast agent concentrations for the following experiments were selected. Second, diffusion rates for both contrast agents were investigated in intact (n = 3) and trypsin-degraded (n = 3) bovine patellar cartilage. The contrast agent concentration of the cartilaginous layer was measured prior to and 2-27 h after immersion. Optimal immersion time for the further experiments was selected. Third, the suitability of gadopentetate and ioxaglate enhanced pQCT to detect the enzymatically induced specific PG depletion was investigated by determining the contrast agent concentrations and uronic acid and water contents in digested and intact osteochondral samples (n = 16). After trypsin-induced PG loss (-70%, p < 0.05) the penetration of gadopentetate and ioxaglate increased (p < 0.05) by 34% and 48%, respectively. Gadopentetate and ioxaglate concentrations both showed strong correlation (r = -0.95, r = -0.94, p < 0.01, respectively) with the uronic acid content. To conclude, contrast agent enhanced pQCT provides a technique to quantify PG content in normal and experimentally

  16. Design of plasmonic circular grating with broadband absorption enhancements

    NASA Astrophysics Data System (ADS)

    Chiu, Nan-Fu; Yang, Cheng-Du; Kao, Yi-Lun; Cheng, Chih-Jen

    2015-05-01

    We have investigated the effect of concentric circles geometry on the performance of focusing plasmonic circular grating (PCG)-coupled surface-omnidirectional absorption. We wish to highlight the essential characteristics of plasmonic circular grating nanostructure to assist researchers in developing and advancing suitable organic solar cells (OSC) for unique applications. Exactly how plasmonic enhancement and the absorption characteristics of the organic materials (P3HT:PCBM and PEDOT:PSS) interact with each other is also examined. We present experimental studies of broadband absorption enhancement in PCG structure. We show that the PCG structure can result in broadband absorption enhancement, the overall optical absorption in organic film can be greatly enhanced up to ~111.2 % compared to the planar device without grating.

  17. Sensitivity of the CCM climate to enhanced cloud absorption

    SciTech Connect

    Kiehl, J.

    1995-09-01

    Recent indications suggest that clouds may be absorbing more solar radiation than was previously thought. This research investigates some of the evidence for this hypothesis; potential physical mechanisms are briefly discussed as well. The climatic implications of the enhanced absorption are investigated using the NCAR Community Climate Model (CCM). It is found that the model`s heat budget in the tropical warm pool agrees more closely with observations when enhanced absorption is included. On the whole, the addition of enhanced absorption improves the model`s performance in the tropics and degrades it in the extra-tropics. 3 figs.

  18. Enhanced light absorption of solar cells and photodetectors by diffraction

    DOEpatents

    Zaidi, Saleem H.; Gee, James M.

    2005-02-22

    Enhanced light absorption of solar cells and photodetectors by diffraction is described. Triangular, rectangular, and blazed subwavelength periodic structures are shown to improve performance of solar cells. Surface reflection can be tailored for either broadband, or narrow-band spectral absorption. Enhanced absorption is achieved by efficient optical coupling into obliquely propagating transmitted diffraction orders. Subwavelength one-dimensional structures are designed for polarization-dependent, wavelength-selective absorption in solar cells and photodetectors, while two-dimensional structures are designed for polarization-independent, wavelength-selective absorption therein. Suitable one and two-dimensional subwavelength periodic structures can also be designed for broadband spectral absorption in solar cells and photodetectors. If reactive ion etching (RIE) processes are used to form the grating, RIE-induced surface damage in subwavelength structures can be repaired by forming junctions using ion implantation methods. RIE-induced surface damage can also be removed by post RIE wet-chemical etching treatments.

  19. Production of silicon modified to have enhanced infrared absorption

    NASA Astrophysics Data System (ADS)

    Weld, E.; Ayachitula, R.; de La Harpe, K.; Brandt, L.; Chilton, M.; Knize, R. J.; Patterson, B. M.

    2014-03-01

    We demonstrate the enhanced optical properties of silicon microstructures formed by irradiation of a silicon wafer by a modulated continuous wave (CW) laser beam in the presence of SF6. The microstructures are doped with about 0.6% sulfur, which extends the absorption well below the 1.1um bandgap of crystalline silicon and results in a 60% increase in the absorption of infrared radiation. The microstructured silicon produced using microsecond pulses of CW light demonstrates comparable infrared absorption enhancement to black silicon made using more expensive and complicated laser systems. This enhanced absorption as a result of these microstructures has been studied over the past decade in an effort to create high responsivity detectors and night vision goggles and improve the efficiency of solar cells. We will also discuss additional methods that allow tunability and scalability in the production of silicon modified to demonstrate increased infrared absorption.

  20. Enhanced absorption in silicon metamaterials waveguide structure

    NASA Astrophysics Data System (ADS)

    Hamouche, Houria; Shabat, Mohammed M.

    2016-07-01

    Metamaterial waveguide structures for silicon solar cells are a novel approach to antireflection coating structures that can be used for the achievement of high absorption in silicon solar cells. This paper investigates numerically the possibility of improving the performance of a planar waveguide silicon solar cell by incorporating a pair of silicon nitride/metamaterial layer between a semi-infinite glass cover layer and a semi-infinite silicon substrate layer. The optimized layer thicknesses of the pair are determined under the solar spectrum AM1.5 by the effective average reflectance method. The transmission and reflection coefficients are derived by the transfer matrix method for values of metamaterial's refractive index in visible and near-infrared radiation. In addition, the absorption coefficient is examined for several angles of incidence of the transverse electric polarized (TE), transverse magnetic polarized (TM) and the total (TE&TM) guided waves. Numerical results provide an extremely high absorption. The absorptivity of the structure achieves greater than 98 %.

  1. Absorption-enhancing effects of gemini surfactant on the intestinal absorption of poorly absorbed hydrophilic drugs including peptide and protein drugs in rats.

    PubMed

    Alama, Tammam; Kusamori, Kosuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2016-02-29

    In general, the intestinal absorption of small hydrophilic molecules and macromolecules like peptides, after oral administration is very poor. Absorption enhancers are considered to be one of the most promising agents to enhance the intestinal absorption of drugs. In this research, we focused on a gemini surfactant, a new type of absorption enhancer. The intestinal absorption of drugs, with or without sodium dilauramidoglutamide lysine (SLG-30), a gemini surfactant, was examined by an in situ closed-loop method in rats. The intestinal absorption of 5(6)-carboxyfluorescein (CF) and fluorescein isothiocyanate-dextrans (FDs) was significantly enhanced in the presence of SLG-30, such effect being reversible. Furthermore, the calcium levels in the plasma significantly decreased when calcitonin was co-administered with SLG-30, suggestive of the increased intestinal absorption of calcitonin. In addition, no significant increase in the of lactate dehydrogenase (LDH) activity or in protein release from the intestinal epithelium was observed in the presence of SLG-30, suggestive of the safety of this compound. These findings indicate that SLG-30 is an effective absorption-enhancer for improving the intestinal absorption of poorly absorbed drugs, without causing serious damage to the intestinal epithelium.

  2. Vibrational resonance enhanced broadband multiphoton absorption in a triphenylamine derivative

    SciTech Connect

    Lu Changgui; Cui Yiping; Huang Wei; Yun Binfeng; Wang Zhuyuan; Hu Guohua; Cui Jing; Lu Zhifeng; Qian Ying

    2007-09-17

    Multiphoton absorption of 2,5-bis[4-(2-N,N-diphenylaminostyryl)phenyl]-1,3,4-oxadiazole was experimentally studied by using femtosecond laser pulses. This material demonstrates a very broad multiphoton absorption band of around 300 nm width with two peaks of 1250 and 1475 nm. The first peak results from the three-photon absorption process while the second is attributed to the vibrational resonance enhanced four-photon absorption process. Combination of these two processes provides a much broader multiphoton absorption band. In this letter, the analytical solution to nonlinear transmission of a three-photon absorption process is also given when the incident beam has a Gaussian transverse spatial profile.

  3. Three-dimensional cloud effects and enhanced atmospheric absorption

    NASA Astrophysics Data System (ADS)

    O'Hirok, William John

    1997-09-01

    Recent global observations suggest that clouds may enhance atmospheric absorption of solar radiation by as much as 15-35 Wm-2 (diurnal average) over theoretical estimates. Considering that doubling of the greenhouse gas, CO2, implies a 4 Wm-2 radiative forcing on the climate system, the large discrepancy between theory and observations is disturbing. In this research, the hypothesis is tested that the plane-parallel assumption employed in climate models provides a partial explanation for discrepancies between theory and observations of atmospheric absorption. To test this hypothesis, a Monte Carlo 3-D radiative transfer model of high spectral and spatial resolution which contains all of the important atmospheric radiative constituents was developed. Computations for a synthetic tropical cloud field, derived from satellite imagery, are performed in 3-D (to represent a realistic cloud) and in two modes which are representative of traditional climate models (plane- parallel and independent pixel). Results show the 3-D cloud effect reduces broadband spatially averaged albedo, increases transmission to the surface, and enhances atmospheric absorption of solar radiation. The enhanced absorption is primarily attributed to greater absorption by water vapor for high overhead sun and increasing absorption by cloud droplets as the sun approaches the horizon. The mechanisms responsible are photon focusing/trapping within the interior of clouds, photon leakage to the lower atmosphere, cloud-side interception of the direct solar beam, cloud interception of reflected photons, and enhanced photon pathlength below layered clouds. From a sensitivity analysis, the most important factor for 3-D enhanced absorption is the vertical structure near the top of the cloud field, followed by the vertical stratification of water vapor. Internal vertical cloud heterogeneity is less important. Spectrally, the 3-D effect reduces absorption in the UV and increases absorption in the gaseous

  4. Meat protein fractions enhance nonheme iron absorption in humans.

    PubMed

    Hurrell, Richard F; Reddy, Manju B; Juillerat, Marcel; Cook, James D

    2006-11-01

    The nature of the enhancing effect of muscle tissue on nonheme iron absorption in humans is unclear but thought to be related to muscle proteins. We conducted radioiron absorption studies to compare iron absorption from proteins isolated from beef and chicken muscle with that from freeze-dried beef and chicken muscle and from egg albumin. All meals contained an equivalent amount of protein as part of a semisynthetic liquid formula. Freeze-dried beef and chicken muscle increased iron absorption 180% (P < 0.001) and 100% (P < 0.001), respectively, relative to egg albumin. When added to the meal at an equivalent protein level (15 g), the isolated beef protein and the isolated heme-free beef protein with 94 and 98% protein content, respectively, increased iron absorption to the same extent as the native beef muscle. Similarly, when added to the meal at an equivalent protein level (30 g), isolated chicken muscle protein (94% protein) increased iron absorption similarly to native chicken muscle. Iron absorption from the meal containing the isolated heme-free chicken protein, however, was 120% (P < 0.01) greater than from the meal containing freeze-dried chicken muscle, indicating that a nonprotein component of muscle tissue with iron-binding potential may have been removed or concentrated by the protein extraction and separation procedures. Our results support the hypothesis that the enhancing effect of muscle tissue on iron absorption is mainly protein related but indicate that other factors may also play a role.

  5. Absorption enhancement and total absorption in a graphene-waveguide hybrid structure

    NASA Astrophysics Data System (ADS)

    Guo, Jun; Wu, Leiming; Dai, Xiaoyu; Xiang, Yuanjiang; Fan, Dianyuan

    2017-02-01

    We propose a graphene/planar waveguide hybrid structure, and demonstrate total absorption in the visible wavelength range by means of attenuated total reflectance. The excitation of planar waveguide mode, which has strong near field enhancement and increased light interaction length with graphene, plays a vital role in total absorption. We analyze the origin and physical insight of total absorption theoretically by using an approximated reflectance, and show how to design such hybrid structure numerically. Utilizing the tunability of doped graphene, we discuss the possible application in optical modulators. We also achieve broadband absorption enhancement in near-IR range by cascading multiple graphene-waveguide hybrid structures. We believe our results will be useful not only for potential applications in optical devices, but also for studying other two-dimension materials.

  6. Enhanced universal absorption of graphene in a Salisbury screen

    NASA Astrophysics Data System (ADS)

    Ying, Xiangxiao; Pu, Yang; Luo, Yi; Peng, Hao; Li, Zhe; Jiang, Yadong; Xu, Jimmy; Liu, Zhijun

    2017-01-01

    As an emerging optoelectronic material, graphene's universal absorption of about 2.3% over a broad frequency range from infrared to visible, as determined by its interband transition, presents both a new opportunity and a limitation. Here we report on a multifold enhancement of the absorption using a simple strategy, often referred to as the Salisbury screen. It consists of a graphene sheet on top of a SiO2 dielectric layer backed with a copper metallic reflector. For a monolayer graphene, peak absorptions of 9% at near normal incidence and 40% at near grazing angle are experimentally demonstrated in the near-infrared region, in good agreement with calculations using transfer matrix method. The resultant absorption enhancement suggests a great potential for graphene to be used in infrared optoelectronic components.

  7. Silver cluster chromophores for absorption enhancement of peptides.

    PubMed

    Kulesza, Alexander; Mitrić, Roland; Bonacić-Koutecký, Vlasta

    2009-04-23

    We present a theoretical study of the structural and optical properties of tripeptide-silver cluster hybrid systems which shows that silver clusters induce significant absorption enhancement in the spectral region between 225 and 350 nm with respect to the pure peptide. This allows the use of clusters as chromophores for absorption enhancement of peptides and proteins and offers a potential for different applications in biosensing. Furthermore, we demonstrate that cluster binding can change the conformational preference for the secondary structure type leading possibly to new functional properties.

  8. Carbon Dioxide Separation from Flue Gas by Phase Enhanced Absorption

    SciTech Connect

    Tim Fout

    2007-06-30

    A new process, phase enhanced absorption, was invented. The method is carried out in an absorber, where a liquid carrier (aqueous solution), an organic mixture (or organic compound), and a gas mixture containing a gas to be absorbed are introduced from an inlet. Since the organic mixture is immiscible or at least partially immiscible with the liquid carrier, the organic mixture forms a layer or small parcels between the liquid carrier and the gas mixture. The organic mixture in the absorber improves mass transfer efficiency of the system and increases the absorption rate of the gas. The organic mixture serves as a transportation media. The gas is finally accumulated in the liquid carrier as in a conventional gas-liquid absorption system. The presence of the organic layer does not hinder the regeneration of the liquid carrier or recovery of the gas because the organic layer is removed by a settler after the absorption process is completed. In another aspect, the system exhibited increased gas-liquid separation efficiency, thereby reducing the costs of operation and maintenance. Our study focused on the search of the organic layer or transportation layer to enhance the absorption rate of carbon dioxide. The following systems were studied, (1) CO{sub 2}-water system and CO{sub 2}-water-organic layer system; (2) CO{sub 2}-Potassium Carbonate aqueous solution system and CO{sub 2}-Potassium Carbonate aqueous solution-organic layer system. CO{sub 2}-water and CO{sub 2}-Potassium Carbonate systems are the traditional gas-liquid absorption processes. The CO{sub 2}-water-organic layer and CO{sub 2}-Potassium Carbonate-organic layer systems are the novel absorption processes, phase enhanced absorption. As we mentioned early, organic layer is used for the increase of absorption rate, and plays the role of transportation of CO{sub 2}. Our study showed that the absorption rate can be increased by adding the organic layer. However, the enhanced factor is highly depended on the

  9. Photonic band-edge-induced enhancement in absorption and emission

    NASA Astrophysics Data System (ADS)

    Ummer, Karikkuzhi Variyath; Vijaya, Ramarao

    2015-01-01

    An enhancement in photonic band-edge-induced absorption and emission from rhodamine-B dye doped polystyrene pseudo gap photonic crystals is studied. The band-edge-induced enhancement in absorption is achieved by selecting the incident angle of the excitation beam so that the absorption spectrum of the emitter overlaps the photonic band edge. The band-edge-induced enhancement in emission, on the other hand, is possible with and without an enhancement in band-edge-induced absorption, depending on the collection angle of emission. Through a simple set of measurements with suitably chosen angles for excitation and emission, we achieve a maximum enhancement of 70% in emission intensity with band-edge-induced effects over and above the intrinsic emission in the case of self-assembled opals. This is a comprehensive effort to interpret tunable lasing in opals as well as to predict the wavelength of lasing arising as a result of band-edge-induced distributed feedback effects.

  10. Absorption-Enhancing Effect of Nitric Oxide on the Absorption of Hydrophobic Drugs in Rat Duodenum.

    PubMed

    Kishimoto, Hisanao; Miyazaki, Kaori; Takizawa, Yusuke; Shirasaka, Yoshiyuki; Inoue, Katsuhisa

    2016-02-01

    Nitric oxide (NO), an endogenous gas that plays a versatile role in the physiological system, has the ability to increase the intestinal absorption of water-soluble compounds through the paracellular route. However, it remains unclear whether NO can enhance the absorption of hydrophobic drugs through the transcellular route. In this study, we examined the absorption-enhancing effect of NO on intestinal permeability of hydrophobic drugs in rat intestine. The pretreatment of rat gastrointestinal sacs with NOC7, a NO-releasing reagent, significantly increased the permeation of griseofulvin from mucosa to serosa in the sacs prepared from the duodenum, but not in those prepared from the other regions such as jejunum, ileum, and colon. The absorption-enhancing effect of NOC7 on the duodenal permeation varied depending on the hydrophobicity of the drugs used. Furthermore, NOC7 treatment was found to be apparently ineffective on the griseofulvin permeation in the duodenum pretreated with dithiothreitol (DTT) that was used as a mucus remover, even though the permeation was increased by pretreatment with DTT alone. These results suggest that NO increases the absorption of hydrophobic drugs through the transcellular route in the duodenum by modulating the mucus layer function.

  11. Carbon Dioxide Separation from Flue Gas by Phase Enhanced Absorption

    SciTech Connect

    Liang Hu

    2006-06-30

    A new process, phase enhanced absorption, was invented. The method is carried out in an absorber, where a liquid carrier (aqueous solution), an organic mixture (or organic compound), and a gas mixture containing a gas to be absorbed are introduced from an inlet. Since the organic mixture is immiscible or at least partially immiscible with the liquid carrier, the organic mixture forms a layer or small parcels between the liquid carrier and the gas mixture. The organic mixture in the absorber improves mass transfer efficiency of the system and increases the absorption rate of the gas. The organic mixture serves as a transportation media. The gas is finally accumulated in the liquid carrier as in a conventional gas-liquid absorption system. The presence of the organic layer does not hinder the regeneration of the liquid carrier or recovery of the gas because the organic layer is removed by a settler after the absorption process is completed. In another aspect, the system exhibited increased gas-liquid separation efficiency, thereby reducing the costs of operation and maintenance. Our study focused on the search of the organic layer or transportation layer to enhance the absorption rate of carbon dioxide. The following systems were studied, (1) CO{sub 2}-water system and CO{sub 2}-water-organic layer system; (2) CO{sub 2}-Potassium Carbonate aqueous solution system and CO{sub 2}-Potassium Carbonate aqueous solution-organic layer system. CO{sub 2}-water and CO{sub 2}-Potassium Carbonate systems are the traditional gas-liquid absorption processes. The CO{sub 2}-water-organic layer and CO{sub 2}-Potassium Carbonate-organic layer systems are the novel absorption processes, phase enhanced absorption. As we mentioned early, organic layer (transportation layer phase) is used for the increase of absorption rate. Our study showed that the absorption rate can be increased by adding the organic layer. However, the enhanced factor is highly depended on the liquid mass transfer

  12. Tunable enhanced optical absorption of graphene using plasmonic perfect absorbers

    SciTech Connect

    Cai, Yijun; Zhu, Jinfeng; Liu, Qing Huo

    2015-01-26

    Enhancement and manipulation of light absorption in graphene is a significant issue for applications of graphene-based optoelectronic devices. In order to achieve this purpose in the visible region, we demonstrate a design of a graphene optical absorber inspired by metal-dielectric-metal metamaterial for perfect absorption of electromagnetic waves. The optical absorbance ratios of single and three atomic layer graphene are enhanced up to 37.5% and 64.8%, respectively. The graphene absorber shows polarization-dependence and tolerates a wide range of incident angles. Furthermore, the peak position and bandwidth of graphene absorption spectra are tunable in a wide wavelength range through a specific structural configuration. These results imply that graphene in combination with plasmonic perfect absorbers have a promising potential for developing advanced nanophotonic devices.

  13. Broadband absorption enhancement in an uncooled microbolometer infrared detector

    NASA Astrophysics Data System (ADS)

    Kebapci, Basak; Dervisoglu, Ozgecan; Battal, Enes; Okyay, Ali Kemal; Akin, Tayfun

    2014-06-01

    This paper introduces a method for a broadband absorption enhancement in the LWIR range (8-12 μm), in single layer microbolometer pixels with 35 μm pitch. For the first time in the literature, this study introduces a very simple and low cost approach to enhance the absorption by embedding plasmonic structures at the same level as the already existing metallic layer of a microbolometer pixel. The metal layer comprises the electrode and the arm structures on the body. Even though the periodicity of the plasmonic structures is slightly disturbed by the placement of the electrodes and the connecting metal, the metal arms and the electrodes compensate for the lack of the periodicity contributing to the resonance by their coupling with the individual plasmonic resonators. Various plasmonic structures are designed with FDTD simulations. Individual, plasmonically modified microbolometer pixels are fabricated, and an increase in the average absorption due to surface plasmon excitation at Au/Si3N4 interfaces is observed. Plasmonic structures increase the average absorption from 78% to 82% and result in an overall enhancement of 5.1%. A good agreement between the simulation and the FTIR measurement results are obtained within the LWIR range. This work paves the way for integration of the plasmonic structures within conventional microbolometer devices for performance enhancement without introducing additional costs.

  14. Methods for deacidizing gaseous mixtures by phase enhanced absorption

    DOEpatents

    Hu, Liang

    2012-11-27

    An improved process for deacidizing a gaseous mixture using phase enhanced gas-liquid absorption is described. The process utilizes a multiphasic absorbent that absorbs an acid gas at increased rate and leads to reduced overall energy costs for the deacidizing operation.

  15. Slow-light enhancement of Beer-Lambert-Bouguer absorption

    NASA Astrophysics Data System (ADS)

    Mortensen, Niels Asger; Xiao, Sanshui

    2007-04-01

    The authors theoretically show how slow light in an optofluidic environment facilitates enhanced light-matter interactions, by orders of magnitude. The proposed concept provides strong opportunities for improving existing miniaturized chemical absorbance cells for Beer-Lambert-Bouguer absorption measurements widely employed in analytical chemistry.

  16. Effect of Surfactant Supplying with Refrigerant Vapor on Absorption Enhancement

    NASA Astrophysics Data System (ADS)

    Gao, Hongtao; Matsuzaki, Tetsuya; Wang, Jianfeng; Hihara, Eiji

    For the absorption of water vapor into the aqueous lithium bromide solution, eight-carbon alcohol additives such as 2-ethyl-1-hexanolhave been commonly used to improve the absorption process. However, as additives six-carbon and seven-carbon alcohols were not been tested experimentally very much. In present study, absorption of water vapor into the 62 wt% LiBr solution with several six-carbon and seven carbon alcohol additives such as 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-hexanol, 2 , 4-dimethyl-3-pentanol, 4-heptanol, 2-heptanol and 1-heptanol were investigated by using a simple stagnant pool absorber. Besides using the conventional method which mixing additive into LiBr solution, vapor phase adding method was experimented. Surface tensions of aqueous LiBr solution with different surfactant also were measured by Welhelmy plate method. Absorption of water vapor into the LiBr solution with 2-ethyl-1-hexanol and 1-heptanol were also experimented in falling film absorber by vapor phase adding method. The result showed that the lower the surface tension of LiBr aqueous solution with an additive, the better the effect of absorption enhancement by the corresponding additive, and vapor phase adding method is effective for the absorption of water vapor into the LiBr aqueous solution.

  17. Chitosan functionalized nanocochleates for enhanced oral absorption of cyclosporine A

    PubMed Central

    Liu, Min; Zhong, Xiaoming; Yang, Zhiwen

    2017-01-01

    It remains a significant challenge to overcome the poor permeability of cyclosporine A and enhance its oral absorption. In this study, we have identified a positively charged chitosan that is able to induce coiling up of anionic lipids to form nanocochleates with an average size of 114.2 ± 0.8 nm, without the need for calcium ions. These functional chitosan-induced nanocochleates enhanced gastrointestinal absorption of cyclosporine A, up to a 3-fold increase in oral bioavailability. A fluorescence-labeling study confirmed that absorption mainly occurred in the duodenum and jejunum. Transport studies indicated that uptake of chitosan-induced nanocochleates by Caco-2 cells was by clathrin- and caveolae-mediated endocytosis, but not by macropinocytosis. Furthermore, three cellular tight junction proteins, ZO-1, F-actin and claudin-4, were significantly down-regulated, suggesting that chitobiose-induced nanocochleates are able to reconstruct and open tight junctions in intestinal epithelial cells to enhance drug absorption. In summary, these novel bifunctional chitosan-induced nanocochleates appear to have potential to facilitate oral delivery of cyclosporine A. PMID:28112262

  18. Cavity enhanced ultra-thin aluminum plasmonic resonator for surface enhanced infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Jiang, Xiao; Nong, Jinpeng; Chen, Na; Lan, Guilian; Tang, Linlong

    2016-11-01

    Owing to the advantages of natural abundance, low cost, and amenability to manufacturing processes, aluminum has recently been recognized as a highly promising plasmonic material that attracts extensive research interest. Here, we propose a cavity-enhanced ultra-thin plasmonic resonator for surface enhanced infrared absorption spectroscopy. The considered resonator consists of a patterned ultra-thin aluminum grating strips, a dielectric spacer layer and a reflective layer. In such structure, the resonance absorption is enhanced by the cavity formed between the patterned aluminum strips and the reflective layer. It is demonstrated that the spectral features of the resonator can be tuned by adjusting the structural parameters. Furthermore, in order to achieve a deep and broad spectral line shape, the spacer layer thickness should be properly designed to realize the simultaneous resonances for the electric and the magnetic excitations. The enhanced infrared absorption characteristics can be used for infrared sensing of the environment. When the resonator is covered with a molecular layer, the resonator can be used as a surface enhanced infrared absorption substrate to enhance the absorption signal of the molecules. A high enhanced factor of 1.15×105 can be achieved when the resonance wavelength of resonator is adjusted to match the desired vibrational mode of the molecules. Such a cavity-enhanced plasmonic resonator, which is easy for practical fabrication, is expected to have potential applications for infrared sensing with high-performance.

  19. Plasmonic electrodes for organic photovoltaics: polarization-independent absorption enhancement

    NASA Astrophysics Data System (ADS)

    Zeng, Beibei; Kafafi, Zakya H.; Bartoli, Filbert J.

    2014-10-01

    We systematically investigate the optical and electrical properties of ultrathin two-dimensional (2D) Ag nanogratings (NGs), and explore their use as plasmonic transparent conducting electrodes in molecular organic photovoltaics (OPVs). A large broadband and polarization-insensitive optical absorption enhancement in the CuPc (copper phthalocyanine): PTCBI (perylene tetracarboxylic bisbenzimidazole) active light-harvesting layers is demonstrated using ultrathin 2D Ag NGs, and is attributed to the excitation of surface plasmon resonances and plasmonic cavity modes.

  20. Method for making a photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1987-05-05

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  1. Nonlinear acoustic enhancement in photoacoustic imaging with wideband absorptive nanoemulsion beads

    NASA Astrophysics Data System (ADS)

    Wei, Chen-wei; Lombardo, Michael; Xia, Jinjun; Pelivanov, Ivan; Perez, Camilo; Larson-Smith, Kjersta; Matula, Thomas J.; Pozzo, Danilo; O'Donnell, Matthew

    2014-03-01

    A nanoemulsion contrast agent with a perfluorohexane core and optically absorptive gold nanospheres (GNSs) assembled on the surface, is presented to improve the specificity of photoacoustic (PA) molecular imaging in differentiating targeted cells or aberrant regions from heterogeneous background signals. Compared to distributed GNSs, clustered GNSs at the emulsion oil-water interface produce a red-shifted and broadened absorption spectrum, exhibiting fairly high absorption in the near-infrared region commonly used for deep tissue imaging. Above a certain laser irradiation fluence threshold, a phase transition creating a microbubble in the emulsion core leads to more than 10 times stronger PA signals compared with conventional thermal-expansion-induced PA signals. These signals are also strongly non-linear, as verified by a differential scheme using recorded PA images at different laser fluences. Assuming a linear relation between laser fluence and the PA signal amplitude, differential processing results in nearly perfect suppression of linear sources, but retains a significant residue for the non-linear nanoemulsion with more than 35 dB enhancement. This result demonstrates that contrast specificity can be improved using the nanoemulsion as a targeting agent in PA molecular imaging by suppressing all background signals related to a linear PA response. Furthermore, combined with a system providing simultaneous laser/ultrasound excitation, cavitation-generated bubbles have the potential to be a highly specific contrast agent for ultrasound molecular imaging and harmonic imaging, as well as a targeted means for noninvasive ultrasound-based therapies.

  2. In vivo photothermal optical coherence tomography for non-invasive imaging of endogenous absorption agents

    PubMed Central

    Makita, Shuichi; Yasuno, Yoshiaki

    2015-01-01

    In vivo photothermal optical coherence tomography (OCT) is demonstrated for cross-sectional imaging of endogenous absorption agents. In order to compromise the sensitivity, imaging speed, and sample motion immunity, a new photothermal detection scheme and phase processing method are developed. Phase-resolved swept-source OCT and fiber-pigtailed laser diode (providing excitation at 406 nm) are combined to construct a high-sensitivity photothermal OCT system. OCT probe and excitation beam coaxially illuminate and are focused on tissues. The photothermal excitation and detection procedure is designed to obtain high efficiency of photothermal effect measurement. The principle and method of depth-resolved cross-sectional imaging of absorption agents with photothermal OCT has been derived. The phase-resolved thermal expansion detection algorithm without motion artifact enables in vivo detection of photothermal effect. Phantom imaging with a blood phantom and in vivo human skin imaging are conducted. A phantom with guinea-pig blood as absorber has been scanned by the photothermal OCT system to prove the concept of cross-sectional absorption agent imaging. An in vivo human skin measurement is also performed with endogenous absorption agents. PMID:26137374

  3. In vivo photothermal optical coherence tomography for non-invasive imaging of endogenous absorption agents.

    PubMed

    Makita, Shuichi; Yasuno, Yoshiaki

    2015-05-01

    In vivo photothermal optical coherence tomography (OCT) is demonstrated for cross-sectional imaging of endogenous absorption agents. In order to compromise the sensitivity, imaging speed, and sample motion immunity, a new photothermal detection scheme and phase processing method are developed. Phase-resolved swept-source OCT and fiber-pigtailed laser diode (providing excitation at 406 nm) are combined to construct a high-sensitivity photothermal OCT system. OCT probe and excitation beam coaxially illuminate and are focused on tissues. The photothermal excitation and detection procedure is designed to obtain high efficiency of photothermal effect measurement. The principle and method of depth-resolved cross-sectional imaging of absorption agents with photothermal OCT has been derived. The phase-resolved thermal expansion detection algorithm without motion artifact enables in vivo detection of photothermal effect. Phantom imaging with a blood phantom and in vivo human skin imaging are conducted. A phantom with guinea-pig blood as absorber has been scanned by the photothermal OCT system to prove the concept of cross-sectional absorption agent imaging. An in vivo human skin measurement is also performed with endogenous absorption agents.

  4. Synergistic Two-Photon Absorption Enhancement in Photosynthetic Light Harvesting

    NASA Astrophysics Data System (ADS)

    Chen, Kuo-Mei; Chen, Yu-Wei; Gao, Ting-Fong

    2012-06-01

    The grand scale fixation of solar energies into chemical substances by photosynthetic reactions of light-harvesting organisms provides Earth's other life forms a thriving environment. Scientific explorations in the past decades have unraveled the fundamental photophysical and photochemical processes in photosynthesis. Higher plants, green algae, and light-harvesting bacteria utilize organized pigment-protein complexes to harvest solar power efficiently and the resultant electronic excitations are funneled into a reaction center, where the first charge separation process takes place. Here we show experimental evidences that green algae (Chlorella vulgaris) in vivo display a synergistic two-photon absorption enhancement in their photosynthetic light harvesting. Their absorption coefficients at various wavelengths display dramatic dependence on the photon flux. This newly found phenomenon is attributed to a coherence-electronic-energy-transfer-mediated (CEETRAM) photon absorption process of light-harvesting pigment-protein complexes of green algae. Under the ambient light level, algae and higher plants can utilize this quantum mechanical mechanism to create two entangled electronic excitations adjacently in their light-harvesting networks. Concerted multiple electron transfer reactions in the reaction centers and oxygen evolving complexes can be implemented efficiently by the coherent motion of two entangled excitons from antennae to the charge separation reaction sites. To fabricate nanostructured, synthetic light-harvesting apparatus, the paramount role of the CEETRAM photon absorption mechanism should be seriously considered in the strategic guidelines.

  5. Absorption enhancement by textured InP in solar cells

    NASA Astrophysics Data System (ADS)

    Yun, Seokhun; Ji, Taeksoo

    2016-03-01

    III-V compound semiconductors seem to be the ideal materials for photovoltaic devices because they exhibit fast carrier velocity. III-V compound semiconductors, however, are unfavorable materials to be commercialized on large scale photovoltaic devices because of their high material cost. The textured surface shows the potential to increase the performance of solar cells because of the properties such as high absorption and longer light path length. These properties can overcome the disadvantage of the III-V compound semiconductors through thin thickness use when producing solar cells. In this study, we demonstrate that textured surfaces on InP formed by nano-sphere lithography and plasma etching process can enhance the absorption effectively in comparison with planar surface. The power conversion efficiency of InP solar cells using the textured InP and the aluminum doped zinc oxide was achieved up to 8%.

  6. Polarization-enhanced absorption spectroscopy for laser stabilization.

    PubMed

    Kunz, Paul D; Heavner, Thomas P; Jefferts, Steven R

    2013-11-20

    We demonstrate a variation of pump-probe spectroscopy that is particularly useful for laser frequency stabilization. The polarization-enhanced absorption spectroscopy (POLEAS) signal provides a significant improvement in signal-to-noise ratio over saturated absorption spectroscopy (SAS) for the important and commonly used atomic cycling transitions. The improvements can directly increase the short-term stability of a laser frequency lock, given sufficient servo loop bandwidth. The long-term stability of the POLEAS method, which is limited by environmental sensitivities, is comparable to that of SAS. The POLEAS signal is automatically Doppler-free, without requiring a separate Doppler subtraction beam, and lends itself to straightforward compact packaging. Finally, by increasing the amplitude of the desired (cycling) peak, while reducing the amplitude of all other peaks in the manifold, the POLEAS method eases the implementation of laser auto-locking schemes.

  7. Microlens array induced light absorption enhancement in polymer solar cells

    SciTech Connect

    Chen, Yuqing; Elshobaki, Moneim; Ye, Zhuo; Park, Joong-Mok; Noack, Max A.; Ho, Kai-Ming; Chaudhary, Sumit

    2013-01-24

    Over the last decade, polymer solar cells (PSCs) have attracted a lot of attention and highest power conversion efficiencies (PCE) are now close to 10%. Here we employ an optical structure – the microlens array (MLA) – to increase light absorption inside the active layer, and PCE of PSCs increased even for optimized devices. Normal incident light rays are refracted at the MLA and travel longer optical paths inside the active layers. Two PSC systems – poly(3-hexylthiophene-2,5-diyl):(6,6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM) and poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:(6,6)-phenyl C71 butyric acid methyl ester (PCDTBT:PC70BM) – were investigated. In the P3HT:PCBM system, MLA increased the absorption, absolute external quantum efficiency, and the PCE of an optimized device by [similar]4.3%. In the PCDTBT:PC70BM system, MLA increased the absorption, absolute external quantum efficiency, and PCE by more than 10%. In addition, simulations incorporating optical parameters of all structural layers were performed and they support the enhancement of absorption in the active layer with the assistance of MLA. Our results show that utilizing MLA is an effective strategy to further increase light absorption in PSCs, in which optical losses account for [similar]40% of total losses. MLA also does not pose materials processing challenges to the active layers since it is on the other side of the transparent substrate.

  8. Polyamidoamine dendrimers as novel potential absorption enhancers for improving the small intestinal absorption of poorly absorbable drugs in rats.

    PubMed

    Lin, Yulian; Fujimori, Takeo; Kawaguchi, Naoko; Tsujimoto, Yuiko; Nishimi, Mariko; Dong, Zhengqi; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2011-01-05

    Effects of polyamidoamine (PAMAM) dendrimers on the intestinal absorption of poorly absorbable drugs were examined by an in situ closed loop method in rats. 5(6)-Carboxyfluorescein (CF), fluorescein isothiocyanate-dextrans (FDs) with various molecular weights, calcitonin and insulin were used as model drugs of poorly absorbable drugs. The absorption of CF, FD4 and calcitonin from the rat small intestine was significantly enhanced in the presence of PAMAM dendrimers. The absorption-enhancing effects of PAMAM dendrimers for improving the small intestinal absorption of CF were concentration and generation dependent and a maximal absorption-enhancing effect was observed in the presence of 0.5% (w/v) G2 PAMAM dendrimer. However, G2 PAMAM dendrimer had almost no absorption-enhancing effect on the small intestinal absorption of macromolecular drugs including FD10 and insulin. Overall, the absorption-enhancing effects of G2 PAMAM dendrimer in the small intestine decreased as the molecular weights of drug increased. However, G2 PAMAM dendrimer did not enhance the intestinal absorption of these drugs with different molecular weights in the large intestine. Furthermore, we evaluated the intestinal membrane damage with or without G2 PAMAM dendrimer. G2 PAMAM dendrimer (0.5% (w/v)) significantly increased the activities of lactate dehydrogenase (LDH) and the amounts of protein released from the intestinal membranes, but the activities and amounts of these toxic markers were less than those in the presence of 3% Triton X-100 used as a positive control. Moreover, G2 PAMAM dendrimer at concentrations of 0.05% (w/v) and 0.1% (w/v) did not increase the activities and amounts of these toxic markers. These findings suggested that PAMAM dendrimers at lower concentrations might be potential and safe absorption enhancers for improving absorption of poorly absorbable drugs from the small intestine.

  9. Quantitative photoacoustic measurement of tissue optical absorption spectrum aided by an optical contrast agent.

    PubMed

    Rajian, Justin Rajesh; Carson, Paul L; Wang, Xueding

    2009-03-16

    In photoacoustic imaging, the intensity of photoacoustic signal induced by optical absorption in biological tissue is proportional to light energy deposition, which is the product of the absorption coefficient and the local light fluence. Because tissue optical properties are highly dependent on the wavelength, the spectrum of the local light fluence at a target tissue beneath the sample surface is different than the spectrum of the incident light fluence. Therefore, quantifying the tissue optical absorption spectrum by using a photoacoustic technique is not feasible without the knowledge of the local light fluence. In this work, a highly accurate photoacoustic measurement of the subsurface tissue optical absorption spectrum has been achieved for the first time by introducing an extrinsic optical contrast agent with known optical properties. From the photoacoustic measurements with and without the contrast agent, a quantified measurement of the chromophore absorption spectrum can be realized in a strongly scattering medium. Experiments on micro-flow vessels containing fresh canine blood buried in phantoms and chicken breast tissues were carried out in a wavelength range from 680 nm to 950 nm. Spectroscopic photoacoustic measurements of both oxygenated and deoxygenated blood specimens presented an improved match with the references when employing this technique.

  10. Broadband infrared absorption enhancement by electroless-deposited silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Gritti, Claudia; Raza, Søren; Kadkhodazadeh, Shima; Kardynal, Beata; Malureanu, Radu; Mortensen, N. Asger; Lavrinenko, Andrei V.

    2017-01-01

    Decorating semiconductor surfaces with plasmonic nanoparticles (NPs) is considered a viable solution for enhancing the absorptive properties of photovoltaic and photodetecting devices. We propose to deposit silver NPs on top of a semiconductor wafer by a cheap and fast electroless plating technique. Optical characterization confirms that the random array of electroless-deposited NPs improves absorption by up to 20% in a broadband of near-infrared frequencies from the bandgap edge to 2000 nm. Due to the small filling fraction of particles, the reflection in the visible range is practically unchanged, which points to the possible applications of such deposition method for harvesting photons in nanophotonics and photovoltaics. The broadband absorption is a consequence of the resonant behavior of particles with different shapes and sizes, which strongly localize the incident light at the interface of a high-index semiconductor substrate. Our hypothesis is substantiated by examining the plasmonic response of the electroless-deposited NPs using both electron energy loss spectroscopy and numerical calculations.

  11. Broadband infrared absorption enhancement by electroless-deposited silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Gritti, Claudia; Raza, Søren; Kadkhodazadeh, Shima; Kardynal, Beata; Malureanu, Radu; Mortensen, N. Asger; Lavrinenko, Andrei V.

    2016-07-01

    Decorating semiconductor surfaces with plasmonic nanoparticles (NPs) is considered a viable solution for enhancing the absorptive properties of photovoltaic and photodetecting devices. We propose to deposit silver NPs on top of a semiconductor wafer by a cheap and fast electroless plating technique. Optical characterization confirms that the random array of electroless-deposited NPs improves absorption by up to 20% in a broadband of near-infrared frequencies from the bandgap edge to 2000 nm. Due to the small filling fraction of particles, the reflection in the visible range is practically unchanged, which points to the possible applications of such deposition method for harvesting photons in nanophotonics and photovoltaics. The broadband absorption is a consequence of the resonant behavior of particles with different shapes and sizes, which strongly localize the incident light at the interface of a high-index semiconductor substrate. Our hypothesis is substantiated by examining the plasmonic response of the electroless-deposited NPs using both electron energy loss spectroscopy and numerical calculations.

  12. Enhanced ex vivo intestinal absorption of olmesartan medoxomil nanosuspension: Preparation by combinative technology.

    PubMed

    Attari, Zenab; Bhandari, Amita; Jagadish, P C; Lewis, Shaila

    2016-01-01

    The purpose of this study was to develop nanosuspension based on combinative technology to enhance the intestinal absorption of Olmesartan medoxomil (OLM), a potent antihypertensive agent with limited oral bioavailability. Two combinative approaches were employed and then characterized. In vitro intestinal absorption of OLM nanosuspension and plain OLM was studied using non-everted rat intestinal sac model. Optimal OLM nanosuspension was prepared by a combination of ball milling and probe sonication using stabilizer, Poloxamer 407. The formula exhibited particle size of 469.9 nm and zeta potential of -19.1 mV, which was subjected to ex vivo studies. The flux and apparent permeability coefficient in intestine from OLM nanosuspension was higher than the plain drug, thereby suggesting better drug delivery.

  13. Broadband enhancement of infrared absorption in microbolometers using Ag nanocrystals

    SciTech Connect

    Hyun, Jerome K.; Ahn, Chi Won; Kim, Woo Choong; Kim, Tae Hyun; Hyun, Moon Seop; Kim, Hee Yeoun E-mail: jhpark@nnfc.re.kr; Park, Jae Hong E-mail: jhpark@nnfc.re.kr; Lee, Won-Oh

    2015-12-21

    High performance microbolometers are widely sought for thermal imaging applications. In order to increase the performance limits of microbolometers, the responsivity of the device to broadband infrared (IR) radiation needs to be improved. In this work, we report a simple, quick, and cost-effective approach to modestly enhance the broadband IR response of the device by evaporating Ag nanocrystals onto the light entrance surface of the device. When irradiated with IR light, strong fields are built up within the gaps between adjacent Ag nanocrystals. These fields resistively generate heat in the nanocrystals and underlying substrate, which is transduced into an electrical signal via a resistive sensing element in the device. Through this method, we are able to enhance the IR absorption over a broadband spectrum and improve the responsivity of the device by ∼11%.

  14. Enhanced absorption of microwaves within cylindrical holes in Teflon film.

    PubMed

    Alekseev, Stanislav I; Fesenko, Evgeny E; Ziskin, Marvin C

    2010-10-01

    Earlier publications demonstrated that 0.9 GHz microwave exposure induced notable changes of the conductivity of modified bilayer lipid membranes (BLM) formed in holes in thin Teflon film (TF). The aims of this study were: 1) to perform detailed calculations of the microwave field distributions in holes formed in TF, using the finite-difference time-domain technique and 2) to model microwave heating of the hole under the conditions used in the BLM experiments but in the absence of BLM in the hole. We found that with the E-field oriented perpendicular to the TF plane the local-specific absorption rate in holes increased significantly. The increase became larger with increasing electrolyte concentration and with decreasing diameter of the hole and frequency. The calculated temperature elevations in the hole were in good agreement with those determined experimentally. These findings allowed us to conclude that the microwave effects on BLM conductivity reported previously resulted mostly from the enhanced absorption of microwave energy by the membrane-forming holes and subsequent local temperature elevation in the holes.

  15. Embedded insulated metallic nanopatterns for enhanced optical absorption and photovoltaics

    NASA Astrophysics Data System (ADS)

    Ye, Fan; Burns, Michael J.; Naughton, Michael J.

    2012-02-01

    Recently, we have shown embedded metallic nanopatterns (EMN) in ultrathin PV films to be candidates for high efficiency thin-film solar cells, owing to prominent metamaterial/plasmonic-enhanced light trapping, as compared to unpatterned, surface- or bottom-patterned [1]. We also showed that hot electron effects emerge in ultrathin a-Si-based solar cells [2]. The EMN in the semiconductor layer, however, can also serve as a source of recombination for photogenerated electrons and holes, leading to decreased current. Here, we propose the idea of an embedded insulated metallic nanopattern (EIMN) to efficiently avoid the recombination effect while maintaining high light absorption in an ultrathin film format in which hot electron physics can contribute. Simulations show that an EIMN with a 10 nm layer of dielectric insulation provides essentially the same absorption as its EMN counterpart. Measurements on several EMN structures will be presented. This EIMN architecture may provide a practical route to high efficiency, hot electron solar cell technology using ultrathin films.[1]F. Ye, M.J. Burns, M.J. Naughton, Proc. SPIE 8111, 811103 (2011).[2]K. Kempa, M.J. Naughton, Z.F. Ren, A. Herczynski, T. Kirkpatrick, J. Rybczynski, Y. Gao, Appl. Phys. Lett. 95, 233121(2009)

  16. Silver nanowires enhance absorption of poly(3-hexylthiophene)

    NASA Astrophysics Data System (ADS)

    Smolarek, Karolina; Ebenhoch, Bernd; Czechowski, Nikodem; Prymaczek, Aneta; Twardowska, Magdalena; Samuel, Ifor D. W.; Mackowski, Sebastian

    2013-11-01

    Results of optical spectroscopy reveal strong influence of plasmon excitations in silver nanowires on the fluorescence properties of poly(3-hexylthiophene) (P3HT), which is one of the building blocks of organic solar cells. For the structure where a conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) was used as a spacer in order to minimize effects associated with non-radiative energy transfer from P3HT to metallic nanoparticles, we demonstrate over two-fold increase of the fluorescence intensity. Results of time-resolved fluorescence indicate that the enhancement of emission intensity can be attributed to increased absorption of P3HT. Our findings are a step towards improving the efficiency of organic solar cells through incorporation of plasmonic nanostructures.

  17. Silver nanowires enhance absorption of poly(3-hexylthiophene)

    SciTech Connect

    Smolarek, Karolina; Czechowski, Nikodem; Prymaczek, Aneta; Twardowska, Magdalena; Mackowski, Sebastian E-mail: mackowski@fizyka.umk.pl; Ebenhoch, Bernd; Samuel, Ifor D. W. E-mail: mackowski@fizyka.umk.pl

    2013-11-11

    Results of optical spectroscopy reveal strong influence of plasmon excitations in silver nanowires on the fluorescence properties of poly(3-hexylthiophene) (P3HT), which is one of the building blocks of organic solar cells. For the structure where a conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) was used as a spacer in order to minimize effects associated with non-radiative energy transfer from P3HT to metallic nanoparticles, we demonstrate over two-fold increase of the fluorescence intensity. Results of time-resolved fluorescence indicate that the enhancement of emission intensity can be attributed to increased absorption of P3HT. Our findings are a step towards improving the efficiency of organic solar cells through incorporation of plasmonic nanostructures.

  18. Method and apparatus for enhanced detection of toxic agents

    DOEpatents

    Greenbaum, Elias; Rodriguez, Jr., Miguel; Wu, Jie Jayne; Qi, Hairong

    2013-10-01

    A biosensor based detection of toxins includes enhancing a fluorescence signal by concentrating a plurality of photosynthetic organisms in a fluid into a concentrated region using biased AC electro-osmosis. A measured photosynthetic activity of the photosynthetic organisms is obtained in the concentrated region, where chemical, biological or radiological agents reduce a nominal photosynthetic activity of the photosynthetic organisms. A presence of the chemical, biological and/or radiological agents or precursors thereof, is determined in the fluid based on the measured photosynthetic activity of the concentrated plurality of photosynthetic organisms. A lab-on-a-chip system is used for the concentrating step. The presence of agents is determined from feature vectors, obtained from processing a time dependent signal using amplitude statistics and/or time-frequency analysis, relative to a control signal. A linear discriminant method including support vector machine classification (SVM) is used to identify the agents.

  19. Near-infrared dye-loaded magnetic nanoparticles as photoacoustic contrast agent for enhanced tumor imaging

    PubMed Central

    Gao, Chuang; Deng, Zi-Jian; Peng, Dong; Jin, Yu-Shen; Ma, Yan; Li, Yan-Yan; Zhu, Yu-Kun; Xi, Jian-Zhong; Tian, Jie; Dai, Zhi-Fei; Li, Chang-Hui; Liang, Xiao-Long

    2016-01-01

    Objective: Photoacoustic (PA) tomography (PAT) has attracted extensive interest because of its optical absorption contrast and ultrasonic detection. This study aims to develop a biocompatible and biodegradable PA contrast agent particularly promising for clinical applications in human body. Methods: In this study, we presented a PA contrast agent: 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine- N-[methoxy (polyethylene glycol)] (DSPE-PEG)-coated superparamagnetic iron oxide (SPIO) nanoparticles (NPs) loaded with indocyanine green (ICG). We used ICG and SPIO NPs because both drugs are approved by the U.S. Food and Drug Administration. Given the strong absorption of near-infrared laser pulses, SPIO@DSPE-PEG/ICG NPs with a uniform diameter of ~28 nm could significantly enhance PA signals. Results: We demonstrated the contrast enhancement of these NPs in phantom and animal experiments, in which the in vivo circulation time of SPIO@DSPE-PEG/ICG NPs was considerably longer than that of free ICG. These novel NPs also displayed a high efficiency of tumor targeting. Conclusions: SPIO@DSPE-PEG/ICG NPs are promising PAT contrast agents for clinical applications. PMID:27807502

  20. Photoacoustic imaging and surface-enhanced Raman spectroscopy using dual modal contrast agents

    NASA Astrophysics Data System (ADS)

    Park, Sungjo; Lee, Seunghyun; Cha, Myeonggeun; Jeong, Cheolhwan; Kang, Homan; Park, So Yeon; Lee, Yoon-sik; Jeong, Daehong; Kim, Chulhong

    2016-03-01

    Recently, photoacoustic tomography (PAT) has emerged as a remarkable non-invasive imaging modality that provides a strong optical absorption contrast, high ultrasonic resolution, and great penetration depth. Thus, PAT has been widely used as an in vivo preclinical imaging tool. Surface-enhanced Raman spectroscopy (SERS) is another attractive sensing technology in biological research because it offers highly sensitive chemical analyses and multiplexed detection. By performing dual-modal imaging of SERS and PAT, high-resolution structural PAT imaging and high-sensitivity SERS sensing can be achieved. At the same time, it is equally important to develop a dual modal contrast agent for this purpose. To perform both PAT and SERS, we synthesized PEGylated silver bumpy nanoshells (AgBSs). The AgBSs generate strong PA signals owing to their strong optical absorption properties as well as sensitive SERS signals because of the surface plasmon resonance effect. Then, multiplexed Raman chemicals were synthesized to enhance the sensitivity of Raman. We have photoacoustically imaged the sentinel lymph nodes of small animals after intradermal injection of multiplexed agents. Furthermore, the chemical composition of each agent has been distinguished through SERS.

  1. Strong enhancement in light absorption by black carbon due to aerosol water uptake

    NASA Astrophysics Data System (ADS)

    Fierce, Laura; Mena, Francisco; Riemer, Nicole; Bond, Tami C.; Bauer, Susanne E.

    2015-04-01

    Black carbon exerts a strong, yet highly uncertain, warming effect on the climate. One source of uncertainty in predicting black carbon's radiative effects is the absorption per black carbon mass. Although models suggest that light absorption is strongly enhanced if black carbon is coated with non-absorbing aerosol material, recent ambient observations find only weak absorption enhancement from aerosol coatings. In this study, we use a particle-resolved aerosol model to evaluate how oversimplified representations of particle composition impact modeled light absorption by black carbon. We show that oversimplifying the representation of particle composition leads to overestimation of modeled absorption enhancement. In order to improve global model representations of BC absorption, we performed a nonparametric regression on particle-reolved model data from a series of simulations. Through this nonparametric analysis we derived a relationship for absorption enhancement as a function of variables that global models already track, the population-averaged composition and the environmental relative humidity. Finally, we show how this nonparametric relationship can be exploited for use in global models to improve predictions of absorption by black carbon. In order to quantify the global-scale impact of water uptake on light absorption by black carbon, we applied the relationship for absorption enhancement to output of the climate model GISS-MATRIX. We find weak absorption enhancement in locations with low relative humidity, but light absorption is strongly enhanced in humid regions. This enhancement in light absorption by particles taking up water strongly impacts black carbon's radiative effects at the global scale, enhancing light absorption by black carbon by 20% relative to dry conditions.

  2. Optical re-injection in cavity-enhanced absorption spectroscopy

    PubMed Central

    Leen, J. Brian; O’Keefe, Anthony

    2014-01-01

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10−10 cm−1/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\sqrt {{\\rm Hz;}}$\\end{document} Hz ; an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features. PMID:25273701

  3. Optical re-injection in cavity-enhanced absorption spectroscopy

    SciTech Connect

    Leen, J. Brian O’Keefe, Anthony

    2014-09-15

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10{sup −10} cm{sup −1}/√(Hz;) an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

  4. Optical re-injection in cavity-enhanced absorption spectroscopy.

    PubMed

    Leen, J Brian; O'Keefe, Anthony

    2014-09-01

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10(-10) cm(-1)/√Hz; an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

  5. Absorption enhancing effects of chitosan oligomers on the intestinal absorption of low molecular weight heparin in rats.

    PubMed

    Zhang, Hailong; Mi, Jie; Huo, Yayu; Huang, Xiaoyan; Xing, Jianfeng; Yamamoto, Akira; Gao, Yang

    2014-05-15

    Absorption enhancing effects of chitosan oligomers with different type and varying concentration on the intestinal absorption of low molecular weight heparin (LMWH) were examined by an in situ closed loop method in different intestinal sections of rats. Chitosan hexamer with the optimal concentration of 0.5% (w/v) showed the highest absorption enhancing ability both in the small intestine and large intestine. The membrane toxicities of chitosan oligomers were evaluated by morphological observation and determining the biological markers including amount of protein and activity of lactate dehydrogenase (LDH) released from intestinal epithelium cells. There was no obvious change both in levels of protein and LDH and morphology in the intestinal membrane between control and various chitosan oligomers groups, suggesting that chitosan oligomers did not induce any significant membrane damage to the intestinal epithelium. In addition, zeta potentials became less negative and amount of free LMWH gradually decreased when various chitosan oligomers were added to LMWH solution, revealing that electrostatic interaction between positively charged chitosan oligomers and negative LMWH was included in the absorption enhancing mechanism of chitosan oligomers. In conclusion, chitosan oligomers, especially chitosan hexamer, are safe and efficient absorption enhancers and can be used promisingly to improve oral absorption of LMWH.

  6. Enzymes and other agents that enhance cell wall extensibility

    NASA Technical Reports Server (NTRS)

    Cosgrove, D. J.

    1999-01-01

    Polysaccharides and proteins are secreted to the inner surface of the growing cell wall, where they assemble into a network that is mechanically strong, yet remains extensible until the cells cease growth. This review focuses on the agents that directly or indirectly enhance the extensibility properties of growing walls. The properties of expansins, endoglucanases, and xyloglucan transglycosylases are reviewed and their postulated roles in modulating wall extensibility are evaluated. A summary model for wall extension is presented, in which expansin is a primary agent of wall extension, whereas endoglucanases, xyloglucan endotransglycosylase, and other enzymes that alter wall structure act secondarily to modulate expansin action.

  7. Enhanced light absorption by mixed source black and brown carbon particles in UK winter

    PubMed Central

    Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; Dubey, Manvendra K.; Cappa, Christopher D.; Williams, Leah R.; Herndon, Scott C.; Massoli, Paola; Fortner, Edward C.; Chhabra, Puneet S.; Brooks, William A.; Onasch, Timothy B.; Jayne, John T.; Worsnop, Douglas R.; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L.; Liu, Dantong; Allan, James D.; Lee, James D.; Fleming, Zoë L.; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S. H.

    2015-01-01

    Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models. PMID:26419204

  8. Enhanced light absorption by mixed source black and brown carbon particles in UK winter.

    PubMed

    Liu, Shang; Aiken, Allison C; Gorkowski, Kyle; Dubey, Manvendra K; Cappa, Christopher D; Williams, Leah R; Herndon, Scott C; Massoli, Paola; Fortner, Edward C; Chhabra, Puneet S; Brooks, William A; Onasch, Timothy B; Jayne, John T; Worsnop, Douglas R; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L; Liu, Dantong; Allan, James D; Lee, James D; Fleming, Zoë L; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S H

    2015-09-30

    Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.

  9. Enhanced Optical Absorption Induced by Dense Nanocavities Inside Titania Nanorods

    SciTech Connect

    Han,W.; Wu, L.; Klie, R.; Zhu, Y.

    2007-01-01

    Titania, a wide band gap semiconductor, can generate powerful oxidants and reductants by absorbing photon energies. Titania has been extensively used in photoelectrochemical systems, such as dye-sensitized titania, a wide band gap semiconductor, can generate powerful oxidants and reductants by absorbing photon energies. To improve the photoreactivity of titania, several approaches, including doping and metal loading have been proposed. Nanocavities are isolated entities inside a solid and hence are very different from nanoporous, whose pores (often amorphous and irregular) connect together and open to the surface. Dense polyhedral nanocavities inside single-crystalline anatase titania nanorods were successfully synthesized by simply heating titanate nanorods. The size of the nanocavities is typically about 10 nm. The surfaces of the nanocavity polyhedron are determined to be the crystallographic low-index planes of the titania crystal. We found that these dense nanocavities significantly enhance the optical absorption coefficient of titania in the near-ultraviolet region, thereby providing a new approach to increasing the photoreactivity of the titania nanorods in the applications related to absorbing photons.

  10. Use of adjuvants for enhancement of rectal absorption of cefoxitin in humans.

    PubMed Central

    Davis, S S; Burnham, W R; Wilson, P; O'Brien, J

    1985-01-01

    The biological availability of cefoxitin administered rectally in the form of suppositories was examined in six human subjects by a cross-over design. Four different suppository systems containing adjuvants expected to enhance the absorption of the drug were studied. The presence of sodium salicylate and a nonionic surface-active agent, Brij 35, gave increased bioavailability as high as 20% compared with 3% for a system without adjuvants. The quantity of sodium salicylate was found to have an influence on the quantity of cefoxitin absorbed, and the salicylate was absorbed over an extended period of time from the rectum. The suppositories were well tolerated, and there were no adverse effects on bowel flora. PMID:3834830

  11. Chitosan oligomers as potential and safe absorption enhancers for improving the pulmonary absorption of interferon-alpha in rats.

    PubMed

    Yamada, Keigo; Odomi, Masaaki; Okada, Naoki; Fujita, Takuya; Yamamoto, Akira

    2005-11-01

    Effects of chitosan oligomers on pulmonary absorption of interferon-alpha (IFN) were examined by means of an in vivo pulmonary absorption experiment. Chitosan oligomers used in this study were chitosan dimer, tetramer, hexamer, and water-soluble (WS) chitosan. A significant increase in serum IFN concentrations was observed after intratracheal administration of IFN with these oligomers. Of these chitosan oligomers, 0.5% w/v chitosan hexamer appeared to be more effective in enhancing the pulmonary absorption of IFN than other oligomers at the same concentration, and the AUC value of IFN with chitosan hexamer increased 2.6-fold as compared with the control. On the other hand, chitosan polymers, which have relatively high molecular weights (22-96 kDa), were not effective in enhancing the pulmonary absorption of IFN due to their low solubility in water. Additionally, the effect of different concentrations (0.1%-1% w/v) of chitosan hexamer on the pulmonary absorption of IFN was studied. Of these different concentrations of chitosan hexamers, the highest AUC value of IFN was obtained in the presence of 0.5% w/v chitosan hexamer. Furthermore, chitosan oligomers did not cause any membrane damage to the rat pulmonary tissues, as determined by leakage of protein and lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid. Therefore, these findings indicated that the use of chitosan oligomers would be a promising approach for improving of the pulmonary absorption of biologically active peptides including IFN.

  12. Vascular targeting agents enhance chemotherapeutic agent activities in solid tumor therapy.

    PubMed

    Siemann, Dietmar W; Mercer, Emma; Lepler, Sharon; Rojiani, Amyn M

    2002-05-01

    The utility of combining the vascular targeting agents 5,6-dimethyl-xanthenone-4 acetic acid (DMXAA) and combretastatin A-4 disodium phosphate (CA4DP) with the anticancer drugs cisplatin and cyclophosphamide (CP) was evaluated in experimental rodent (KHT sarcoma), human breast (SKBR3) and ovarian (OW-1) tumor models. Doses of the vascular targeting agents that led to rapid vascular shutdown and subsequent extensive central tumor necrosis were identified. Histologic evaluation showed morphologic damage of tumor cells within a few hours after treatment, followed by extensive hemorrhagic necrosis and dose-dependent neoplastic cell death as a result of prolonged ischemia. Whereas these effects were induced by a range of CA4DP doses (10-150 mg/kg), the dose response to DMXAA was extremely steep; doses < or = 15 mg/kg were ineffective and doses > or = 20 mg/kg were toxic. DMXAA also enhanced the tumor cell killing of cisplatin, but doses > 15 mg/kg were required. In contrast, CA4DP increased cisplatin-induced tumor cell killing at all doses studied. This enhancement of cisplatin efficacy was dependent on the sequence and interval between the agents. The greatest effects were achieved when the vascular targeting agents were administered 1-3 hr after cisplatin. When CA4DP (100 mg/kg) or DMXAA (17.5 mg/kg) were administered 1 hr after a range of doses of cisplatin or CP, the tumor cell kill was 10-500-fold greater than that seen with chemotherapy alone. In addition, the inclusion of the antivascular agents did not increase bone marrow stem cell toxicity associated with these anticancer drugs, thus giving rise to a therapeutic gain.

  13. Rapid chemical agent identification by surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Yuan-Hsiang; Farquharson, Stuart

    2001-08-01

    Although the Chemical Weapons Convention prohibits the development, production, stockpiling, and use of chemical warfare agents (CWAs), the use of these agents persists due to their low cost, simplicity in manufacturing and ease of deployment. These attributes make these weapons especially attractive to low technology countries and terrorists. The military and the public at large require portable, fast, sensitive, and accurate analyzers to provide early warning of the use of chemical weapons. Traditional laboratory analyzers such as the combination of gas chromatography and mass spectroscopy, although sensitive and accurate, are large and require up to an hour per analysis. New, chemical specific analyzers, such as immunoassays and molecular recognition sensors, are portable, fast, and sensitive, but are plagued by false-positives (response to interferents). To overcome these limitations, we have been investigating the potential of surface-enhanced Raman spectroscopy (SERS) to identify and quantify chemical warfare agents in either the gas or liquid phase. The approach is based on the extreme sensitivity of SERS demonstrated by single molecule detection, a new SERS material that we have developed to allow reproducible and reversible measurements, and the molecular specific information provided by Raman spectroscopy. Here we present SER spectra of chemical agent simulants in both the liquid and gas phase, as well as CWA hydrolysis phase.

  14. Rapid biological agent identification by surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Farquharson, Stuart; Smith, Wayne W.; Elliott, Susan; Sperry, Jay F.

    1999-11-01

    The Chemical Weapons Convention prohibits the development, production, stockpiling, and use of warfare agents (chemical and biological), and requires their destruction. Yet their use persists and has been included in the terrorist's arsenal. Currently, a number of analytical methods are being developed to perform rapid measurements of trace agents to ensure treaty compliance, as well as safe environments for military personal and the public at large. We have been investigating the ability of surface-enhanced Raman spectroscopy to detect bacterial nucleic acid-base pairs with sufficient sensitivity and selectivity to eliminate the need for enumeration used in polymerase chain reactions and culture growth, required by other measurement techniques. The design of a small volume, fiber optic coupled, electrolytic sample cell is presented along with analysis of DNA and RNA separated from non-toxic bacteria.

  15. Can immunostimulatory agents enhance the abscopal effect of radiotherapy?

    PubMed

    Levy, Antonin; Chargari, Cyrus; Marabelle, Aurelien; Perfettini, Jean-Luc; Magné, Nicolas; Deutsch, Eric

    2016-07-01

    Ionising radiation (IR) may harm cancer cells through a rare indirect out-of-field phenomenon described as the abscopal effect. Increasing evidence demonstrates that radiotherapy could be capable of generating tumour-specific immune responses. On the other hand, effects of IR also include inhibitory immune signals on the tumour microenvironment. Following these observations, and in the context of newly available immunostimulatory agents in metastatic cancers (anti-cytotoxic T lymphocyte-associated antigen 4 and programmed cell death protein-1 or -ligand 1 [PD1 or PDL-1]), there is a remarkable potential for synergistic combinations of IR with such agents that act through the reactivation of immune surveillance. Here, we present and discuss the pre-clinical and clinical rationale supporting the enhancement of the abscopal effect of IR on the blockade of immune checkpoints and discuss the evolving potential of immunoradiotherapy.

  16. Quantifying Plasmon-Enhanced Light Absorption in Monolayer WS2 Films.

    PubMed

    Butun, Serkan; Palacios, Edgar; Cain, Jeffrey D; Liu, Zizhuo; Dravid, Vinayak P; Aydin, Koray

    2017-04-10

    Transition metal dichalcogenide semiconductors hold great promise in photonic and optoelectronic applications such as flexible solar cells and ultrafast photodetectors due to their direct band-gap and few-atom thicknesses. However, it is crucial to understand and improve the absorption characteristics of these monolayer semiconducting materials. In this paper, we performed a systematic numerical and experimental investigation to demonstrate and quantify absorption enhancement in WS2 monolayer films, in the presence of silver plasmonic nanodisk arrays. Our analysis combining full-field electromagnetic simulations and optical absorption spectroscopy measurements indicate a 4-fold enhancement in the absorption of WS2 film near its band edge, close to the plasmonic resonance wavelength of Ag nanodisk arrays. Proposed Ag/WS2 heterostructure exhibited 2.5-fold enhancement in calculated short circuit current. Such hybrid plasmonic/2D materials with enhanced absorption pave the way towards practical realization of 2D optoelectronic devices including ultrafast photodetectors and solar cells.

  17. Plasmonic absorption enhancement in organic solar cells by nano disks in a buffer layer

    NASA Astrophysics Data System (ADS)

    Kim, Inho; Seok Jeong, Doo; Seong Lee, Taek; Seong Lee, Wook; Lee, Kyeong-Seok

    2012-05-01

    We demonstrate using finite-difference-time-domain calculations that embedding Ag nano disks (NDs) in the buffer layers of thin P3HT:PCBM organic solar cells can enhance optical absorption in the active layers at specific wavelength range. We show that the aspect ratio of the NDs is a key parameter for strong plasmonic absorption enhancement. Two different plasmonic absorption bands are observed stemming from optical refractive index differences among the layers surrounding the NDs in the solar cell devices. One absorption band by the surface plasmon mode localized at the interface of indium tin oxide/ND, which is undesirable for plasmonic absorption enhancement in the active layer, become negligible as the aspect ratio of the diameter-to-height increased. The other absorption band by the dipole-like surface plasmon mode, which plays a main role in enhancing the absorption in the active layer, is spectrally tunable by adjusting the aspect ratio of the NDs. The influences of diameter, height, and coverage of the NDs on optical absorption in the active layer are discussed. Embedding the optimal size NDs in the buffer layer leads to the enhanced total absorption in the 50 nm thick active layer by 16% relative to that without the NDs, and the optical absorption keeps enhanced with increasing the active layer thickness up to 90 nm. However, further increases in the active layer thickness are detrimental to absorption enhancement, which is considered to be caused by destructive interference between scattered light by the NDs and incident light.

  18. CHAMPION: Intelligent Hierarchical Reasoning Agents for Enhanced Decision Support

    SciTech Connect

    Hohimer, Ryan E.; Greitzer, Frank L.; Noonan, Christine F.; Strasburg, Jana D.

    2011-11-15

    We describe the design and development of an advanced reasoning framework employing semantic technologies, organized within a hierarchy of computational reasoning agents that interpret domain specific information. Designed based on an inspirational metaphor of the pattern recognition functions performed by the human neocortex, the CHAMPION reasoning framework represents a new computational modeling approach that derives invariant knowledge representations through memory-prediction belief propagation processes that are driven by formal ontological language specification and semantic technologies. The CHAMPION framework shows promise for enhancing complex decision making in diverse problem domains including cyber security, nonproliferation and energy consumption analysis.

  19. Wideband enhancement of infrared absorption in a direct band-gap semiconductor by using nonabsorptive pyramids.

    PubMed

    Dai, Weitao; Yap, Daniel; Chen, Gang

    2012-07-02

    Efficient trapping of the light in a photon absorber or a photodetector can improve its performance and reduce its cost. In this paper we investigate two designs for light-trapping in application to infrared absorption. Our numerical simulations demonstrate that nonabsorptive pyramids either located on top of an absorbing film or having embedded absorbing rods can efficiently enhance the absorption in the absorbing material. A spectrally averaged absorptance of 83% is achieved compared to an average absorptance of 28% for the optimized multilayer structure that has the same amount of absorbing material. This enhancement is explained by the coupled-mode theory. Similar designs can also be applied to solar cells.

  20. Binding of anti-prion agents to glycosaminoglycans: Evidence from electronic absorption and circular dichroism spectroscopy

    SciTech Connect

    Zsila, Ferenc . E-mail: zsferi@chemres.hu; Gedeon, Gabor

    2006-08-11

    The polyanionic glycosaminoglycans (GAGs) are intimately involved in the pathogenesis of protein conformational disorders such as amyloidosis and prion diseases. Several cationic agents are known to exhibit anti-prion activity but their mechanism of action is poorly understood. In this study, UV absorption and circular dichroism (CD) spectroscopic techniques were used to investigate the interaction between heparin and chondroitin-6-sulfate and anti-prion drugs including acridine, quinoline, and phenothiazine derivatives. UV band hypochromism of ({+-})-quinacrine, ({+-})-primaquine, tacrine, quinidine, chlorpromazine, and induced CD spectra of ({+-})-quinacrine upon addition of GAGs provided evidence for the GAG binding of these compounds. The association constants ({approx}10{sup 6}-10{sup 7} M{sup -1}) estimated from the UV titration curves show high-affinity drug-heparin interactions. Ionic strength-dependence of the absorption spectra suggested that the interaction between GAGs and the cationic drugs is principally electrostatic in nature. Drug binding differences of heparin and chondroitin-6-sulfate were attributed to their different negative charge density. These results call the attention to the alteration of GAG-prion/GAG-amyloid interactions by which these compounds might exert their anti-prion/anti-amyloidogenic activities.

  1. Percutaneous absorption, disposition, and exposure assessment of homosalate, a UV filtering agent, in rats.

    PubMed

    Kim, Tae Hwan; Shin, Beom Soo; Kim, Kyu-Bong; Shin, Seung Woo; Seok, Su Hyun; Kim, Min Kyu; Kim, Eun Jung; Kim, Dojung; Kim, Min Gi; Park, Eun-Seok; Kim, Ju-Young; Yoo, Sun Dong

    2014-01-01

    Homosalate (HMS) is an ultraviolet (UV) filtering agent used in sunscreens and other cosmetics for skin protection purposes. Despite the widespread use of these products, absorption, disposition, and in vivo endocrine disrupting potential of HMS have not been characterized. Thus, the aim of this study was to examine the percutaneous absorption, disposition, and exposure assessment of HMS in rats. Initially, sunscreen preparations of petrolatum jelly, oily solution, lotion, and gel were prepared and evaluated for in vitro permeation of HMS across excised rat skin. Dermal permeability was greatest for gel, and this preparation was used in subsequent in vivo topical application investigations. After iv injection (0.5, 2, or 5 mg/kg), the pharmacokinetics of HMS was linear and was characterized by a large Vd(ss) (13.2-17 L/kg), high Cl(s) (4.5-6.1 L/h/kg), and long t½ (6.1-8.4 h). After topical application of gel, the bioavailability of HMS was 5.4 ± 1.1 and 4.2 ± 0.6% for high and low doses (10 and 20 mg), respectively. Consistent with the prolonged absorption (Tmax 11.2 ± 1.8 and 12 ± 0 h for low and high doses, respectively), the terminal t½ was longer after topical application (23.6-26.1 h) compared to iv injection. A population pharmacokinetic model was further developed to simultaneously fit the time courses of plasma concentrations and dermal content data after iv injection and topical application. Findings of this study may be useful to further examine the relationship between exposure and endocrine disrupting potential of HMS in risk assessment.

  2. Chemical agent detection by surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Farquharson, Stuart; Gift, Alan; Maksymiuk, Paul; Inscore, Frank E.; Smith, Wayne W.; Morrisey, Kevin; Christesen, Steven D.

    2004-03-01

    In the past decade, the Unites States and its allies have been challenged by a different kind of warfare, exemplified by the terrorist attacks of September 11, 2001. Although suicide bombings are the most often used form of terror, military personnel must consider a wide range of attack scenarios. Among these is the intentional poisoning of water supplies to obstruct military operations in Afghanistan and Iraq. To counter such attacks, the military is developing portable analyzers that can identify and quantify potential chemical agents in water supplies at microgram per liter concentrations within 10 minutes. To aid this effort we have been investigating the value of a surface-enhanced Raman spectroscopy based portable analyzer. In particular we have been developing silver-doped sol-gels to generate SER spectra of chemical agents and their hydrolysis products. Here we present SER spectra of several chemical agents measured in a generic tap water. Repeat measurements were performed to establish statistical error associated with SERS obtained using the sol-gel coated vials.

  3. Stabilizing Agents for Calibration in the Determination of Mercury Using Solid Sampling Electrothermal Atomic Absorption Spectrometry

    PubMed Central

    Zelinková, Hana; Červenka, Rostislav; Komárek, Josef

    2012-01-01

    Tetramethylene dithiocarbamate (TMDTC), diethyldithiocarbamate (DEDTC), and thiourea were investigated as stabilizing agents for calibration purposes in the determination of mercury using solid sampling electrothermal atomic absorption spectrometry (SS-ETAAS). These agents were used for complexation of mercury in calibration solutions and its thermal stabilization in a solid sampling platform. The calibration solutions had the form of methyl isobutyl ketone (MIBK) extracts or MIBK-methanol solutions with the TMDTC and DEDTC chelates and aqueous solutions with thiourea complexes. The best results were obtained for MIBK-methanol solutions in the presence of 2.5 g L−1 TMDTC. The surface of graphite platforms for solid sampling was modified with palladium or rhenium by using electrodeposition from a drop of solutions. The Re modifier is preferable due to a higher lifetime of platform coating. A new SS-ETAAS procedure using the direct sampling of solid samples into a platform with an Re modified graphite surface and the calibration against MIBK-methanol solutions in the presence of TMDTC is proposed for the determination of mercury content in solid environmental samples, such as soil and plants. PMID:22654606

  4. Absorption enhancement of a dual-band metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Zhong, Min; Han, Gui Ming; Liu, Shui Jie; Xu, Bang Li; Wang, Jie; Huang, Hua Qing

    2017-02-01

    In this paper, we propose and fabricate a dual-band metamaterial absorber in 6-24 THz region. Electric field distribution reveal that the first absorption band is obtained from localized surface plasmon (LSP) modes which are excited both on inside and outside edges of each circular-patterned metal-dielectric stack, while the second absorption band is excited by LSP modes on outside edges of each stack. Measured results indicate that the absorption band width can be tuned by increasing the radius of circular-patterned layers or reducing the thickness of dielectric spacing layers. Moreover, the designed dual-band metamaterial absorber is independent on circular-patterned dielectric layer combinations.

  5. A platform for colorful solar cells with enhanced absorption

    NASA Astrophysics Data System (ADS)

    Dhindsa, Navneet; Walia, Jaspreet; Singh Saini, Simarjeet

    2016-12-01

    We demonstrate submicron thick platform integrating amorphous silicon nanowires and thin-films achieving vivid colors in transmission and reflection. The platform nearly doubles the absorption efficiency compared to the starting thin-film without much compromising with color diverseness. The structural colors can be changed over a wide range by changing the diameters of the nanowires while still keeping the absorption efficiency higher than starting thin-film. The optical response of the platform is conceptually understood for different diameters combined with different thin-film thicknesses indicating the presence of leaky waveguide modes and coupled cavity modes. Our proposed platform can enable architectural low price colorful solar cells on transparent substrates.

  6. A platform for colorful solar cells with enhanced absorption.

    PubMed

    Dhindsa, Navneet; Walia, Jaspreet; Saini, Simarjeet Singh

    2016-12-09

    We demonstrate submicron thick platform integrating amorphous silicon nanowires and thin-films achieving vivid colors in transmission and reflection. The platform nearly doubles the absorption efficiency compared to the starting thin-film without much compromising with color diverseness. The structural colors can be changed over a wide range by changing the diameters of the nanowires while still keeping the absorption efficiency higher than starting thin-film. The optical response of the platform is conceptually understood for different diameters combined with different thin-film thicknesses indicating the presence of leaky waveguide modes and coupled cavity modes. Our proposed platform can enable architectural low price colorful solar cells on transparent substrates.

  7. Enhancement of the oral absorption of cyclosporin in man.

    PubMed Central

    Drewe, J; Meier, R; Vonderscher, J; Kiss, D; Posanski, U; Kissel, T; Gyr, K

    1992-01-01

    1. The oral absorption of cyclosporin from three new semi-solid oral formulations was compared with the standard soft gelatine preparation in twelve healthy male volunteers. One formulation was based on a solid micellar solution, while the other two, with different in vitro release properties, were based on a microemulsion principle. 2. The results showed that the solid micellar solution and the faster releasing microemulsion formulation increased the extent of absorption on average by 45.2 and 49.0%, respectively, compared with the reference soft gelatine capsule. PMID:1633069

  8. Enhanced absorption of graphene in the visible region by use of plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Hashemi, Mahdieh; Farzad, Mahmood Hosseini; Asger Mortensen, N.; Xiao, Sanshui

    2013-05-01

    Low absorption of graphene in the visible range of the spectrum makes it difficult to uniquely benefit from this material in ultra-fast optoelectronic applications. We numerically propose to utilize patterned metallic nanostructures to increase light absorption in single-layer graphene. Simulation results show that excitation of surface plasmon resonances in the metallic nanostructures significantly enhances the local electromagnetic field near the graphene layer, therefore leading to a dramatic enhancement of the absorption in the graphene layer itself. Broadband high optical absorption can be realized by engineering the metal nanostructures, while maintaining insensitivity to the incident angle. Our results pave a new and promising way to enhance visible-light absorption in the graphene layer, which is potentially interesting for graphene-based photovoltaics.

  9. Enhancement of broadband optical absorption in photovoltaic devices by band-edge effect of photonic crystals.

    PubMed

    Tanaka, Yoshinori; Kawamoto, Yosuke; Fujita, Masayuki; Noda, Susumu

    2013-08-26

    We numerically investigate broadband optical absorption enhancement in thin, 400-nm thick microcrystalline silicon (µc-Si) photovoltaic devices by photonic crystals (PCs). We realize absorption enhancement by coupling the light from the free space to the large area resonant modes at the photonic band-edge induced by the photonic crystals. We show that multiple photonic band-edge modes can be produced by higher order modes in the vertical direction of the Si photovoltaic layer, which can enhance the absorption on multiple wavelengths. Moreover, we reveal that the photonic superlattice structure can produce more photonic band-edge modes that lead to further optical absorption. The absorption average in wavelengths of 500-1000 nm weighted to the solar spectrum (AM 1.5) increases almost twice: from 33% without photonic crystal to 58% with a 4 × 4 period superlattice photonic crystal; our result outperforms the Lambertian textured structure.

  10. Sequential multiphoton absorption enhancement induced by zinc complexation in functionalized distyrylbenzene analogs.

    PubMed

    Fabbrini, Graziano; Riccò, Raffaele; Menna, Enzo; Maggini, Michele; Amendola, Vincenzo; Garbin, Mattia; Villano, Massimo; Meneghetti, Moreno

    2007-02-07

    Functionalized distyrylbenzene analogs and , bearing a tris-(2-pyridylmethyl)amine-based receptor for Zn(2+), were synthesized by a Horner-Emmons-Wittig coupling reaction. It has been found that Zn(2+) complexation induces changes in the linear absorption spectrum that enhance a nonlinear sequential two-photon absorption of nanosecond pulses at 532 nm. This absorption was also found to depend on the nature of the substituent at the side benzene ring of the styrylbenzene structure.

  11. Radiant energy absorption enhancement in optical imaging systems

    NASA Technical Reports Server (NTRS)

    Brown, R. M.; Gunter, W. D., Jr.

    1971-01-01

    Reimaging system efficiently uses incident light and overcomes previous imaging detector problems. Optical system collects reflected and focal plane transmitted light and redirects it so it again impinges on focal plane in register with original image. Reimaging unabsorbed light increases light absorption and detector use probability.

  12. Enhanced nasal absorption of hydrophilic markers after dosing with AT1002, a tight junction modulator.

    PubMed

    Song, Keon-Hyoung; Fasano, Alessio; Eddington, Natalie D

    2008-05-01

    AT1002 is a six-mer synthetic peptide, H-FCIGRL-OH, that retains the delta G and Zot biological activity of reversibly opening tight junctions and increases the paracellular transport of drugs. The objective of this study was to evaluate the possible use of AT1002 in enhancing the nasal availability of macromolecules using large paracellular markers as model agents. Male Sprague-Dawley rats cannulated in the jugular vein were randomly assigned to receive radiolabelled paracellular markers, [14C]PEG4000 or [14C]inulin, with/without AT1002, for each intranasal study. The plasma concentration of PEG4000 with AT1002 (10mg/kg) was significantly higher than that from PEG4000 control over 360 min following intranasal administration. The AUC0-360 min and Cmax from the PEG4000/AT1002 (10mg/kg) treatment were statistically (p<0.05) increased to 235% and 357%, of control, respectively. When inulin was administered with AT1002 (10 mg/kg), the plasma concentration was significantly higher (p<0.05) than control over 360 min, and increases (p<0.05) of 292% and 315% for AUC0-360 min and Cmax over control were observed, respectively. AT1002 significantly increased the nasal absorption of molecular weight markers, PEG4000 and inulin. This study suggests that AT1002 may be used to enhance the systemic availability of macromolecules when administered concurrently.

  13. Enhanced Collaboration for Space Situational Awareness via Proxy Agents

    NASA Astrophysics Data System (ADS)

    Picciano, P.; Schurr, N.

    2012-09-01

    The call for dynamic partnerships demanded in the US. Space Policy confronts two formidable challenges. The first is evident in the lack of the adoption of technical innovations that could substantially enhance collaboration. The second category, and perhaps a greater impediment, involves organizational and social constraints that minimize information sharing. Compounding the technical challenges, the organizational barriers to collaboration present a different problem set. There is a culture in the space domain that predisposes most stakeholders to guard their information. Most owner/operators are reluctant to share asset data, whether experiencing an anomaly or just providing status updates. This is unfortunate, because the owner/operators generally have the most accurate and timely data pertaining to their satellite. Comprehensive Space Situational Awareness (SSA) requires the marshaling of disparate mission critical elements. The mission threads reliant on SSA are complex and often require analysis from a diverse team of experts with sophisticated systems and tools that may be dispersed across multiple entities including military, commercial, and public interests. Two significant trends are likely to further perpetuate this state of affairs: 1) the space environment continues to be more congested, contested, and competitive, and 2) further pressures to increase SSA Sharing with a greater number of stakeholders throughout the world. The challenge of delivering the right information to the right people, while protecting national security and privacy interests, is in need of an innovative solution. Our approach, entitled Space Collaboration via an Agent Network (SCAN), enables proxy software agents to represent stakeholders (as individuals and organizations) to enhance collaboration among various agency producers and consumers of space information The SCAN agent network will facilitate collaboration by identifying opportunities to collaborate, as well as optimize

  14. The effect of particle vertical positioning on the absorption enhancement in plasmonic organic solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Shu-Yi; Borca-Tasciuc, Diana-Andra; Kaminski, Deborah A.

    2012-06-01

    The light absorption enhancement of an organic solar cell with plasmonic nanoparticles (NP) embedded in the active layer is studied employing 3D finite element simulation. The effect of the vertical positioning of the particle monolayer inside the active layer is elucidated. The results indicate that the highest enhancement is obtained when the particles lay at the bottom of the active layer, an organization less difficult to control accurately in practice. The paper also discusses the difference in the absorption enhancement obtained for two existing definitions currently used in the literature. The results show that models assessing absorption by taking both host and nanoparticles into consideration may overpredict the enhancement even when integration is carried out only over the wavelength interval where the host absorption dominates.

  15. Optical design of transparent metal grids for plasmonic absorption enhancement in ultrathin organic solar cells.

    PubMed

    Kim, Inho; Lee, Taek Seong; Jeong, Doo Seok; Lee, Wook Seong; Kim, Won Mok; Lee, Kyeong-Seok

    2013-07-01

    Transparent metal grid combining with plasmonic absorption enhancement is a promising replacement to indium tin oxide thin films. We numerically demonstrate metal grids in one or two dimension lead to plasmonic absorption enhancements in ultrathin organic solar cells. In this paper, we study optical design of metal grids for plasmonic light trapping and identify different plasmonic modes of the surface plasmon polaritons excited at the interfaces of glass/metal grids, metal grids/active layers, and the localized surface plasmon resonance of the metal grids using numerical calculations. One dimension metal grids with the optimal design of a width and a period lead to the absorption enhancement in the ultrathin active layers of 20 nm thickness by a factor of 2.6 under transverse electric polarized light compared to the case without the metal grids. Similarly, two dimensional metal grids provide the absorption enhancement by a factor of 1.8 under randomly polarized light.

  16. Absorption efficiency enhancement in inorganic and organic thin film solar cells via plasmonic honeycomb nanoantenna arrays.

    PubMed

    Tok, Rüştü Umut; Sendur, Kürşat

    2013-08-15

    We demonstrate theoretically that by embedding plasmonic honeycomb nanoantenna arrays into the active layers of inorganic (c-Si) and organic (P3HT:PCBM/PEDOT:PSS) thin film solar cells, absorption efficiency can be improved. To obtain the solar cell absorption spectrum that conforms to the solar radiation, spectral broadening is achieved by breaking the symmetry within the Wigner-Seitz unit cell on a uniform hexagonal grid. For optimized honeycomb designs, absorption efficiency enhancements of 106.2% and 20.8% are achieved for c-Si and P3HT:PCBM/PEDOT:PSS thin film solar cells, respectively. We have demonstrated that the transverse modes are responsible for the enhancement in c-Si solar cells, whereas both the longitudinal and transverse modes, albeit weaker, are the main enhancement mechanisms for P3HT:PCBM/PEDOT:PSS solar cells. For both inorganic and organic solar cells, the absorption enhancement is independent of polarization.

  17. Broken-cloud enhancement of solar radiation absorption

    SciTech Connect

    Byrne, R.N.; Somerville, R.C.; Subasilar, B.

    1996-04-01

    Two papers recently published in Science have shown that there is more absorption of solar radiation than estimated by current atmospheric general circulation models (GCMs) and that the discrepancy is associated with cloudy scenes. We have devised a simple model which explains this as an artifact of stochastic radiative transport. We first give a heuristic description, unencumbered by mathematical detail. Consider a simple case with clouds distributed at random within a single level whose upper and lower boundaries are fixed. The solar zenith angle is small to moderate; this is therefore an energetically important case. Fix the average areal liquid water content of the cloud layer, and take the statistics of the cloud distribution to be homogeneous within the layer. Furthermore, assume that all the clouds in the layer have the same liquid water content, constant throughout the cloud, and that apart from their droplet content they are identical to the surrounding clear sky. Let the clouds occupy on the average a fraction p{sub cld} of the volume of the cloudy layer, and let them have a prescribed distribution of sizes about some mean. This is not a fractal distribution, because it has a scale. Cloud shape is unimportant so long as cloud aspect ratios are not far from unity. Take the single-scattering albedo to be unity for the droplets in the clouds. All of the absorption is due to atmospheric gases, so the absorption coefficient at a point is the same for cloud and clear sky. Absorption by droplets is less than 10% effect in the numerical stochastic radiation calculations described below, so it is reasonable to neglect it at this level of idealization.

  18. Spontaneous emission enhancement and saturable absorption of colloidal quantum dots coupled to photonic crystal cavity.

    PubMed

    Gupta, Shilpi; Waks, Edo

    2013-12-02

    We demonstrate spontaneous emission rate enhancement and saturable absorption of cadmium selenide colloidal quantum dots coupled to a nanobeam photonic crystal cavity. We perform time-resolved lifetime measurements and observe an average enhancement of 4.6 for the spontaneous emission rate of quantum dots located at the cavity as compared to those located on an unpatterned surface. We also demonstrate that the cavity linewidth narrows with increasing pump intensity due to quantum dot saturable absorption.

  19. Identification of biological agents using surface enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Paxon, Tracy L.; Duthie, R. Scott; Renko, Casey; Burns, Andrew A.; Lesaicherre, Marie L.; Mondello, Frank J.

    2011-05-01

    GE Global Research Center, in collaboration with Morpho Detection, Inc. has developed an assay scheme for the identification of biological agents using Surface Enhanced Raman Scattering (SERS). Specifically, unique spectroscopic signatures are generated using SERS tags consisting of individual glass-encapsulated gold nanoparticles and surfacebound reporter molecules. These SERS tags are modified with a capture moiety specific to the antigen of interest, and serve as a spectroscopic label in a bead-based sandwich assay. Assays are being developed for a variety of pathogens and this paper will focus on aspects of assay development, optimization, stabilization and validation. Results on the development of an assay to detect Ricin toxin will be presented, and preliminary feasibility studies for the detection of additional pathogens will be discussed.

  20. Black-carbon absorption enhancement in the atmosphere determined by particle mixing state

    NASA Astrophysics Data System (ADS)

    Liu, Dantong; Whitehead, James; Alfarra, M. Rami; Reyes-Villegas, Ernesto; Spracklen, Dominick V.; Reddington, Carly L.; Kong, Shaofei; Williams, Paul I.; Ting, Yu-Chieh; Haslett, Sophie; Taylor, Jonathan W.; Flynn, Michael J.; Morgan, William T.; McFiggans, Gordon; Coe, Hugh; Allan, James D.

    2017-02-01

    Atmospheric black carbon makes an important but poorly quantified contribution to the warming of the global atmosphere. Laboratory and modelling studies have shown that the addition of non-black-carbon materials to black-carbon particles may enhance the particles’ light absorption by 50 to 60% by refracting and reflecting light. Real-world experimental evidence for this `lensing’ effect is scant and conflicting, showing that absorption enhancements can be less than 5% or as large as 140%. Here we present simultaneous quantifications of the composition and optical properties of individual atmospheric black-carbon particles. We show that particles with a mass ratio of non-black carbon to black carbon of less than 1.5, which is typical of fresh traffic sources, are best represented as having no absorption enhancement. In contrast, black-carbon particles with a ratio greater than 3, which is typical of biomass-burning emissions, are best described assuming optical lensing leading to an absorption enhancement. We introduce a generalized hybrid model approach for estimating scattering and absorption enhancements based on laboratory and atmospheric observations. We conclude that the occurrence of the absorption enhancement of black-carbon particles is determined by the particles’ mass ratio of non-black carbon to black carbon.

  1. Enhanced rectal absorption of beta-lactam antibiotics in rat by monodesmosides isolated from pericarps of Sapindus mukurossi (Enmei-hi).

    PubMed

    Yata, N; Sugihara, N; Yamajo, R; Murakami, T; Higashi, Y; Kimata, H; Nakayama, K; Kuzuki, T; Tanaka, O

    1985-12-01

    Monodesmosides, saponin A,B and C, isolated from pericarps of Sapindus mukurossi (Enmei-hi) were shown to promote the rectal absorption of beta-lactam antibiotics in rat, using an in situ loop method and an in vivo method. In the in situ loop method, monodesmosides were solubilized with a mixture of bisdesmosides, mukurozi-saponin X, Y1 and Y2, each of which was isolated from pericarps of Sapindus mukurossi. The promoting functions of the three monodesmosides for the rectal absorption of antibiotics were comparable and also suppressed by Ca2+ ion coexisting in the administered solution. Unlike the case of N-acylcollagenpeptides, which were also previously reported as absorption promoters, no influence of osmolarity of the administered solution on the absorption promoting action was observed. Absorption of beta-lactam antibiotics from suppositories was enhanced with the aid of either of monodesmosides without solubilizing agent.

  2. Broadband light absorption enhancement in polymer photovoltaics using metal nanowall gratings as transparent electrodes

    SciTech Connect

    Ye, Zhuo; Chaudhary, Sumit; Kuang, Ping; Ho, Kai-Ming

    2012-05-15

    The authors investigate light absorption in organic solar cells in which indium tin oxide (ITO) is replaced by a new metallic architecture (grating) as a transparent electrode. Different from typical metal nanowire gratings, our gratings consist of metal nanowalls with nanoscale footprint and (sub)microscale height [Adv. Mater. 23, 2469 (2011)], thus ensuring high optical transmittance and electrical conductivity. Simulations reveal that a broadband and polarization-insensitive light absorption enhancement is achieved via two mechanisms, when such silver nanowall gratings are employed in P3HT:PCBM based solar cells. Overall absorption enhanced by ~23% compared to a reference cell with ITO electrode.

  3. Optimal design of laterally assembled hexagonal silicon nanowires for broadband absorption enhancement in ultrathin solar cells

    NASA Astrophysics Data System (ADS)

    Shahraki, Mojtaba; Salehi, Mohammad Reza; Abiri, Ebrahim

    2015-11-01

    Design approaches to carry out broadband absorption in laterally assembled hexagonal silicon nanowire (NW) solar cells are investigated. Two different methods are proposed to improve the current density of silicon NW solar cells. It is observed that the key to the broadband absorption is disorder and irregularity. The first approach to reach the broadband absorption is using multiple NWs with different geometries. Nevertheless, the maximum enhancement is obtained by introducing irregular NWs. They can support more cavity modes, while scattering by NWs leads to broadening of the absorption spectra. An array of optimized irregular NWs also has preferable features compared to other broadband structures. Using irregular NW arrays, it is possible to improve the absorption enhancement of solar cells without introducing more absorbing material.

  4. Spectral Fingerprinting of Individual Cells Visualized by Cavity-Reflection-Enhanced Light-Absorption Microscopy

    PubMed Central

    Arai, Yoshiyuki; Yamamoto, Takayuki; Minamikawa, Takeo; Takamatsu, Tetsuro; Nagai, Takeharu

    2015-01-01

    The absorption spectrum of light is known to be a “molecular fingerprint” that enables analysis of the molecular type and its amount. It would be useful to measure the absorption spectrum in single cell in order to investigate the cellular status. However, cells are too thin for their absorption spectrum to be measured. In this study, we developed an optical-cavity-enhanced absorption spectroscopic microscopy method for two-dimensional absorption imaging. The light absorption is enhanced by an optical cavity system, which allows the detection of the absorption spectrum with samples having an optical path length as small as 10 μm, at a subcellular spatial resolution. Principal component analysis of various types of cultured mammalian cells indicates absorption-based cellular diversity. Interestingly, this diversity is observed among not only different species but also identical cell types. Furthermore, this microscopy technique allows us to observe frozen sections of tissue samples without any staining and is capable of label-free biopsy. Thus, our microscopy method opens the door for imaging the absorption spectra of biological samples and thereby detecting the individuality of cells. PMID:25950513

  5. Spectral fingerprinting of individual cells visualized by cavity-reflection-enhanced light-absorption microscopy.

    PubMed

    Arai, Yoshiyuki; Yamamoto, Takayuki; Minamikawa, Takeo; Takamatsu, Tetsuro; Nagai, Takeharu

    2015-01-01

    The absorption spectrum of light is known to be a "molecular fingerprint" that enables analysis of the molecular type and its amount. It would be useful to measure the absorption spectrum in single cell in order to investigate the cellular status. However, cells are too thin for their absorption spectrum to be measured. In this study, we developed an optical-cavity-enhanced absorption spectroscopic microscopy method for two-dimensional absorption imaging. The light absorption is enhanced by an optical cavity system, which allows the detection of the absorption spectrum with samples having an optical path length as small as 10 μm, at a subcellular spatial resolution. Principal component analysis of various types of cultured mammalian cells indicates absorption-based cellular diversity. Interestingly, this diversity is observed among not only different species but also identical cell types. Furthermore, this microscopy technique allows us to observe frozen sections of tissue samples without any staining and is capable of label-free biopsy. Thus, our microscopy method opens the door for imaging the absorption spectra of biological samples and thereby detecting the individuality of cells.

  6. Enhancement of Absorption by Micro-Mixing induced by Villi Motion

    NASA Astrophysics Data System (ADS)

    Wang, Yanxing; Brasseur, James; Banco, Gino

    2009-11-01

    Motions of surface villi create microscale flows that can couple with lumen-scale eddies to enhance absorption at the epithelium of the small intestine. Using a multigrid strategy within the lattice-Boltzmann framework, we model a macro-scale cavity flow with microscale ``villi'' in pendular motion on the lower surface and evaluate the couplings between macro and micro-scale fluid motions, scalar mixing, and uptake of passive scalar at the villi surface. We study the influences of pendular frequency, villous length, and villous groupings on absorption rate. The basic mechanism underlying the enhancement of absorption rate by a villous-induced ``micro-mixing layer'' (MML) is the microscale ``pumping'' of low concentration fluid from between groups of villi coupled with the return of high concentration fluid into the villi groups from the macroscale flow. The MML couples with the macrosacle eddies through a diffusion layer that separates micro and macro mixed layers. The absorption rate increases with frequency of villi oscillation due to enhanced vertical pumping. We discover a critical villus length above which absorption rate increases significantly. The absorption is influenced by villus groupings in a complex way due to the interference between vertical and horizontal geometry vs. MML scales. We conclude that optimized villi motility can enhance absorption and may underlie an explanation for the existence of villi in the gut. [Supported by NSF

  7. Effect of fibre and coupling agent contents on water absorption and flexural modulus of wood fibre polyethylene composites

    NASA Astrophysics Data System (ADS)

    Tissandier, C.; Zhang, Y.; Rodrigue, D.

    2014-05-01

    In two previous studies, wood fiber-reinforced polymer composites (WPC) were prepared via melt processing. In particular, a response surface strategy of a 20 run optimal design for these three factors was adopted. It was found that for these WPC mixing torque, melt viscosity, Young's modulus and tensile stress at break were related to the type of wood used, as well as wood and coupling agent contents. In addition, thermal properties and strain at break were mainly affected by wood and coupling agent contents. Here, a more complete characterization of these WPC under extreme environmental conditions is performed. In particular, the effect of coupling agent content, wood fibre content and wood fibre type on water absorption and flexural modulus are reported under different water immersion time and temperature. The results show that water absorption is influenced by all the parameters studied, while flexural modulus is mainly influenced by wood content and immersion temperature.

  8. Preventive obesity agent montmorillonite adsorbs dietary lipids and enhances lipid excretion from the digestive tract

    PubMed Central

    Xu, Pengfei; Dai, Shu; Wang, Jing; Zhang, Jun; Liu, Jin; Wang, Fang; Zhai, Yonggong

    2016-01-01

    Western diets are typically high in fat and are associated with long-term complications such as obesity and hepatic steatosis. Because of the enjoyable taste of high-fat diets (HFDs), we are interested in determining how to decrease lipid absorption and enhance lipid excretion from the digestive tract after the consumption of eating fatty foods. Montmorillonite was initially characterized as a gastrointestinal mucosal barrier protective agent for the treatment of diarrhoea. Dietary lipid adsorbent- montmorillonite (DLA-M) was isolated and purified from Xinjiang montmorillonite clay via the water extraction method. Here, we show that DLA-M has an unexpected role in preventing obesity, hyperlipidaemia and hepatic steatosis in HFD-fed rats. Interestingly, combined application of polarized light microscopy and lipid staining analyses, showed that DLA-M crystals have dietary lipid-adsorbing ability in vitro and in vivo, which enhances lipid excretion via bowel movements. In summary, our results indicate that DLA-M prevent HFD-induced obesity. This novel dietary lipid-adsorbing agent can help prevent obesity and its comorbidities. PMID:26891902

  9. Nanoimprint-Transfer-Patterned Solids Enhance Light Absorption in Colloidal Quantum Dot Solar Cells.

    PubMed

    Kim, Younghoon; Bicanic, Kristopher; Tan, Hairen; Ouellette, Olivier; Sutherland, Brandon R; García de Arquer, F Pelayo; Jo, Jea Woong; Liu, Mengxia; Sun, Bin; Liu, Min; Hoogland, Sjoerd; Sargent, Edward H

    2017-04-12

    Colloidal quantum dot (CQD) materials are of interest in thin-film solar cells due to their size-tunable bandgap and low-cost solution-processing. However, CQD solar cells suffer from inefficient charge extraction over the film thicknesses required for complete absorption of solar light. Here we show a new strategy to enhance light absorption in CQD solar cells by nanostructuring the CQD film itself at the back interface. We use two-dimensional finite-difference time-domain (FDTD) simulations to study quantitatively the light absorption enhancement in nanostructured back interfaces in CQD solar cells. We implement this experimentally by demonstrating a nanoimprint-transfer-patterning (NTP) process for the fabrication of nanostructured CQD solids with highly ordered patterns. We show that this approach enables a boost in the power conversion efficiency in CQD solar cells primarily due to an increase in short-circuit current density as a result of enhanced absorption through light-trapping.

  10. Effect of the additional anode layers on the absorption enhancement characteristic of plasmonic organic solar cells

    NASA Astrophysics Data System (ADS)

    Yoo, Sanghyuk; Kim, Jungho

    2014-12-01

    We numerically investigate the effect of additional anode layers on the absorption enhancement characteristic of pyramidal-grating plasmonic organic solar cells (OSCs) using the finite element method. The behaviors of the plasmonic absorption enhancement are compared between a “simple” structure consisting of only the active and metal cathode layers and a “practical” structure with the additional anode layers. The plasmonic absorption enhancement is identified by comparing the polarization-dependent absorbance spectra between the planar and plasmonic OSCs. When the active-layer thickness is small, the plasmonic resonance condition changes owing to the addition of the anode layers. When the active-layer thickness is large, the plasmonic resonance condition and corresponding absorption behavior show a slight difference irrespective of the inclusion of the additional anode layers. Therefore, the additional anode layers should be included in the optical analysis and design of plasmonic OSCs when the active-layer thickness is small.

  11. Graphene-sandwiched silicon structures for greatly enhanced unpolarized light absorption

    NASA Astrophysics Data System (ADS)

    Shi, Kaifeng; Haque, Riaz R.; Mao, Ling-Feng; Lu, Zhaolin

    2015-03-01

    Based on the attenuated total reflection configuration, a multi-layer graphene (MLG) sandwiched silicon structure is proposed for greatly enhancing light absorption over a broad spectral range (1000-2000 nm). At specific incident angles, the electric field in the sandwiched graphene can be simultaneously enhanced for both transverse electric (TE) and transverse magnetic (TM) polarized light. Numerical analysis and finite-difference time-domain simulation demonstrate over 80% and 70% light absorption for TE- and TM-polarized light, respectively. Owing to the unique optical properties of graphene, the absorption of any photon by graphene may give rise to an electron-hole pair. Thus, the greatly enhanced absorption of unpolarized, broadband light may find significant applications in future photovoltaic devices. However, the excess energy carried by the electron-hole pair can dissipate within a sub-picosecond due to the ultra-fast intraband carrier relaxation, which is the challenge for photovoltaic application and will also be discussed.

  12. Absorption Enhancement in Organic–Inorganic Halide Perovskite Films with Embedded Plasmonic Gold Nanoparticles

    PubMed Central

    2015-01-01

    We report on the numerical analysis of solar absorption enhancement in organic–inorganic halide perovskite films embedding plasmonic gold nanoparticles. The effect of particle size and concentration is analyzed in realistic systems in which random particle location within the perovskite film and the eventual formation of dimers are also taken into account. We find a maximum integrated solar absorption enhancement of ∼10% in perovskite films of 200 nm thickness and ∼6% in 300 nm films, with spheres of radii 60 and 90 nm, respectively, in volume concentrations of around 10% in both cases. We show that the presence of dimers boosts the absorption enhancement up to ∼12% in the thinnest films considered. Absorption reinforcement arises from a double contribution of plasmonic near-field and scattering effects, whose respective weight can be discriminated and evaluated from the simulations. PMID:26500712

  13. Enhanced light absorption by mixed source black and brown carbon particles in UK winter

    SciTech Connect

    Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; Dubey, Manvendra K.; Cappa, Christopher D.; Williams, Leah R.; Herndon, Scott C.; Massoli, Paola; Fortner, Edward C.; Chhabra, Puneet S.; Brooks, William A.; Onasch, Timothy B.; Jayne, John T.; Worsnop, Douglas R.; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L.; Liu, Dantong; Allan, James D.; Lee, James D.; Fleming, Zoë L.; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S. H.

    2015-09-30

    We report that black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC’s light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ~1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC’s warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. In conclusion, we find that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.

  14. Enhanced light absorption by mixed source black and brown carbon particles in UK winter

    DOE PAGES

    Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; ...

    2015-09-30

    We report that black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC’s light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ~1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC’s warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combinationmore » of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. In conclusion, we find that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.« less

  15. Enhancing drugs absorption through third-degree burn wound eschar.

    PubMed

    Manafi, Ali; Hashemlou, Azadeh; Momeni, Parisa; Moghimi, Hamid R

    2008-08-01

    Antimicrobial therapy remains the most important method of wound infection treatment. Systemically administered antimicrobials may not achieve therapeutic levels in wound. On the other hand, some topically applied antimicrobials cannot penetrate eschar well enough. Therefore, an attempt has been made here to increase permeation of topically applied drugs through eschar using the so-called skin penetration enhancers. To perform this investigation, effects of different potential penetration enhancers on permeation of chlorhexidine, silver sulfadiazine and nitroglycerin through human third-degree burn eschar was evaluated. Results showed that water, glycerin, saline, sodium lauryl sulphate (SDS) and ethanol tend to reduce permeation of chlorhexidine through burn eschar. But, water, glycerin, hexane:ethanol and ethyl acetate:ethanol were able to increase permeation of silver sulfadiazine significantly by about 1.2-1.8 times, while saline, SDS and dimethyl sulfoxide were not able to change its permeation. Glycine showed 2.7 times enhancement toward permeation of nitroglycerin, followed by water, hexane:ethanol mixture, saline and SDS with enhancement ratios of 1.8-2.3. Urea, ethanol and citral were not able to increase permeation of nitroglycerin through eschar. This study shows that permeation of drugs through burn eschar can be improved by penetration enhancement including hydration; the effect depends on the nature of the penetrant.

  16. Light absorption enhancement of black carbon from urban haze in Northern China winter.

    PubMed

    Chen, Bing; Bai, Zhe; Cui, Xinjuan; Chen, Jianmin; Andersson, August; Gustafsson, Örjan

    2017-02-01

    Atmospheric black carbon (BC) is an important pollutant for both air quality and Earth's energy balance. Estimates of BC climate forcing remain highly uncertain, e.g., due to the mixing with non-absorbing components. Non-absorbing aerosols create a coating on BC and may thereby act as a lens which may enhance the light absorption. However, this absorption enhancement is poorly constrained. To this end a two-step solvent dissolution protocol was employed to remove both organic and inorganic coatings, and then investigate their effects on BC light absorption. Samples were collected at a severely polluted urban area, Jinan, in the North China Plain (NCP) during February 2014. The BC mass absorption cross-section (MAC) was measured for the aerosol samples before and after the solvent-decoating treatment, and the enhancement of MAC (EMAC) from the coating effect was defined as the ratio. A distinct diurnal pattern for the enhancement was observed, with EMAC 1.3 ± 0.3 (1 S.D.) in the morning, increasing to 2.2 ± 1.0 in the afternoon, after that dropping to 1.5 ± 0.8 in the evening-night. The BC absorption enhancement primarily was associated with urban-scale photochemical production of nitrate and sulfate aerosols. In addition to that, regional-scale haze plume with increasing sulfate levels strengthened the absorption enhancement. These observations offer direct evidence for an increased absorption enhancement of BC due to severe air pollution in China.

  17. 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.

  18. Enhancement of X-ray dose absorption for medical applications

    NASA Astrophysics Data System (ADS)

    Lim, Sara; Nahar, S.; Pradhan, A.; Barth, R.

    2013-05-01

    A promising technique for cancer treatment is radiation therapy with high-Z (HZ) nanomoities acting as radio-sensitizers attached to tumor cells and irradiated with X-rays. But the efficacy of radiosenstization is highly energy dependent. We study the physical effects in using platinum (Pt) as the radio-sensitizing agent, coupled with commonly employed broadband x-ray sources with mean energies around 100 keV, as opposed to MeV energies produced by clinical linear accelerators (LINAC) used in radiation therapy. Numerical calculations, in vitro, and in vivo studies of F98 rat glioma (brain cancer) demonstrate that irradiation from a medium energy X-ray (MEX) 160 kV source is far more effective than from a high energy x-ray (HEX) 6 MV LINAC. We define a parameter to quantify photoionization by an x-ray source, which thereby provides a measure of subsequent Auger decays. The platinum (Z = 78) results are also relevant to ongoing studies on x-ray interaction with gold (Z = 79) nanoparticles, widely studied as an HZ contrast agent. The present study should be of additional interest for a combined radiation plus chemotherapy treatment since Pt compounds such cis-Pt and carbo-Pt are commonly used in chemotherapy.

  19. Enhancing agents for phytoremediation of soil contaminated by cyanophos.

    PubMed

    Ali Romeh, Ahmed

    2015-07-01

    Cyanophos is commonly used in Egypt to control various agricultural and horticultural pests. It is a strong contaminant in the crop culturing environments because it is highly persistent and accumulates in the soil. This contaminant can be removed by phytoremediation, which is the use of plants to clean-up pollutants. Here we tested several several strategies to improve the effectiveness of this technology, which involved various techniques to solubilize contaminants. The phytoremediation efficiency of Plantago major L. was improved more by liquid silicon dioxide (SiO₂) than by other solubility-enhancing agents, resulting in the removal of significant amounts of cyanophos from contaminated soil. Liquid SiO₂ increased the capacity of P. major L. to remove cyanophos from soil by 45.9% to 74.05%. In P. major L. with liquid SiO₂, leaves extracted more cyanophos (32.99 µg/g) than roots (13.33 µg/g) over 3 days. The use of solubilization agents such as surfactants, hydroxypropyl-ß-cyclodextrin (HPßCD), natural humic acid acid (HA), and Tween 80 resulted in the removal of 60 convergents of cyanophos from polluted soil. Although a batch equilibrium technique showed that use of HPßCD resulted in the efficient removal of cyanophos from soil, a greater amount of cyanophos was removed by P. major L. with SiO₂. Moreover, a large amount of cyanophos was removed from soil by rice bran. This study indicates that SiO₂ can improve the efficiency of phytoremediation of cyanophos.

  20. Enhancing absorption properties of composite nanosphere and nanowire arrays by localized surface plasmon resonance shift

    NASA Astrophysics Data System (ADS)

    Tang, Xiaobing; Zhou, Leping; Du, Xiaoze; Yang, Yongping

    Nanoparticles with nonmetallic core and metallic shell can improve the spectral solar absorption efficiency for traditional working fluids, due to the localized surface plasmon resonance (LSPR) effect exists at the surfaces of these core-shell composite nanoparticles. In this work, the effect of geometry and material, and hence the LSPR effect, on the optical absorption properties of core-shell nanostructures was numerically demonstrated by the finite difference time domain method. The nanostructures were formed by varying the inner and outer radii of the composite nanospheres and nanowires and by changing the particle spacing for their arrays. The result indicates that varying the inner radius itself can tune the absorption efficiency factors of the nanostructures monotonously, while an optimal outer radius may exist for maximizing the absorption efficiency factors. It also shows that varying the inner radius itself can widen the absorption spectrums for the arrays, but the absorptance tends to increase with decreasing inner radius or particle spacing. Meanwhile, the second absorption peaks may be observed for nanowires or nanosphere/nanowire arrays, which can be tuned by the resonance shifts induced by the change of either inner or outer radius and hence the LSPR effect. The coupled LSPR effect under studied can be efficiently utilized for tuning the optical absorption properties of nanoparticles used in many applications including photothermal conversion, and perspective also exists for many other applications including surface-enhanced Raman spectroscopy (SERS) enhancement.

  1. Multiband enhanced absorption of monolayer graphene with attenuated total reflectance configuration and sensing application

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Bu, Lingbing; Chen, Yunyun; Zheng, Gaige; Zou, Xiujuan; Xu, Linhua; Wang, Jicheng

    2017-01-01

    An enhanced absorption of monolayer graphene is obtained in a multilayer film-based attenuated total reflectance configuration in the visible wavelength range. The enhanced absorption under transverse magnetic and electric conditions is associated with the excitation of the waveguide mode in the thin-film layer, which is verified by the numerical calculation of field profiles. The obtained results manifest that the model induces a high field enhancement at the graphene-dielectric interface with the resonant angle, which implies potential sensing applications. The magnitude of the figure of merit is found to be three times higher than that of a conventional surface plasmon sensor.

  2. Large Absorption Enhancement in Ultrathin Solar Cells Patterned by Metallic Nanocavity Arrays

    PubMed Central

    Wang, Wei; Zhang, Jiasen; Che, Xiaozhou; Qin, Guogang

    2016-01-01

    A new type of light trapping structure utilizing ring-shaped metallic nanocavity arrays is proposed for the absorption enhancement in ultrathin solar cells with few photonic waveguide modes. Dozens of times of broadband absorption enhancement in the spectral range of 700 to 1100 nm is demonstrated in an ultrathin Si3N4/c-Si/Ag prototype solar cell by means of finite-difference time-domain (FDTD) simulation, and this dramatic absorption enhancement can be attributed to the excitation of plasmonic cavity modes in these nanocavity arrays. The cavity modes optimally compensate for the lack of resonances in the longer wavelength range for ultrathin solar cells, and eventually a maximum Jsc enhancement factor of 2.15 is achieved under AM 1.5G solar illumination. This study opens a new perspective for light management in thin film solar cells and other optoelectronic devices. PMID:27703176

  3. Comparing plasmonic and dielectric gratings for absorption enhancement in thin-film organic solar cells.

    PubMed

    Le, Khai Q; Abass, Aimi; Maes, Bjorn; Bienstman, Peter; Alù, Andrea

    2012-01-02

    We theoretically investigate and compare the influence of square silver gratings and one-dimensional photonic crystal (1D PC) based nanostructures on the light absorption of organic solar cells with a thin active layer. We show that, by integrating the grating inside the active layer, excited localized surface plasmon modes may cause strong field enhancement at the interface between the grating and the active layer, which results in broadband absorption enhancement of up to 23.4%. Apart from using silver gratings, we show that patterning a 1D PC on top of the device may also result in a comparable broadband absorption enhancement of 18.9%. The enhancement is due to light scattering of the 1D PC, coupling the incoming light into 1D PC Bloch and surface plasmon resonance modes.

  4. Large Absorption Enhancement in Ultrathin Solar Cells Patterned by Metallic Nanocavity Arrays

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Zhang, Jiasen; Che, Xiaozhou; Qin, Guogang

    2016-10-01

    A new type of light trapping structure utilizing ring-shaped metallic nanocavity arrays is proposed for the absorption enhancement in ultrathin solar cells with few photonic waveguide modes. Dozens of times of broadband absorption enhancement in the spectral range of 700 to 1100 nm is demonstrated in an ultrathin Si3N4/c-Si/Ag prototype solar cell by means of finite-difference time-domain (FDTD) simulation, and this dramatic absorption enhancement can be attributed to the excitation of plasmonic cavity modes in these nanocavity arrays. The cavity modes optimally compensate for the lack of resonances in the longer wavelength range for ultrathin solar cells, and eventually a maximum Jsc enhancement factor of 2.15 is achieved under AM 1.5G solar illumination. This study opens a new perspective for light management in thin film solar cells and other optoelectronic devices.

  5. The multicopper ferroxidase hephaestin enhances intestinal iron absorption in mice.

    PubMed

    Fuqua, Brie K; Lu, Yan; Darshan, Deepak; Frazer, David M; Wilkins, Sarah J; Wolkow, Natalie; Bell, Austin G; Hsu, JoAnn; Yu, Catherine C; Chen, Huijun; Dunaief, Joshua L; Anderson, Gregory J; Vulpe, Chris D

    2014-01-01

    Hephaestin is a vertebrate multicopper ferroxidase important for the transfer of dietary iron from intestinal cells to the blood. Hephaestin is mutated in the sex-linked anemia mouse, resulting in iron deficiency. However, sex-linked anemia mice still retain some hephaestin ferroxidase activity. They survive, breed, and their anemia improves with age. To gain a better understanding of the role of hephaestin in iron homeostasis, we used the Cre-lox system to generate knockout mouse models with whole body or intestine-specific (Villin promoter) ablation of hephaestin. Both types of mice were viable, indicating that hephaestin is not essential and that other mechanisms, multicopper ferroxidase-dependent or not, must compensate for hephaestin deficiency. The knockout strains, however, both developed a microcytic, hypochromic anemia, suggesting severe iron deficiency and confirming that hephaestin plays an important role in body iron acquisition. Consistent with this, the knockout mice accumulated iron in duodenal enterocytes and had reduced intestinal iron absorption. In addition, the similarities of the phenotypes of the whole body and intestine-specific hephaestin knockout mice clarify the important role of hephaestin specifically in intestinal enterocytes in maintaining whole body iron homeostasis. These mouse models will serve as valuable tools to study the role of hephaestin and associated proteins in iron transport in the small intestine and other tissues.

  6. The Multicopper Ferroxidase Hephaestin Enhances Intestinal Iron Absorption in Mice

    PubMed Central

    Fuqua, Brie K.; Lu, Yan; Darshan, Deepak; Frazer, David M.; Wilkins, Sarah J.; Wolkow, Natalie; Bell, Austin G.; Hsu, JoAnn; Yu, Catherine C.; Chen, Huijun; Dunaief, Joshua L.; Anderson, Gregory J.; Vulpe, Chris D.

    2014-01-01

    Hephaestin is a vertebrate multicopper ferroxidase important for the transfer of dietary iron from intestinal cells to the blood. Hephaestin is mutated in the sex-linked anemia mouse, resulting in iron deficiency. However, sex-linked anemia mice still retain some hephaestin ferroxidase activity. They survive, breed, and their anemia improves with age. To gain a better understanding of the role of hephaestin in iron homeostasis, we used the Cre-lox system to generate knockout mouse models with whole body or intestine-specific (Villin promoter) ablation of hephaestin. Both types of mice were viable, indicating that hephaestin is not essential and that other mechanisms, multicopper ferroxidase-dependent or not, must compensate for hephaestin deficiency. The knockout strains, however, both developed a microcytic, hypochromic anemia, suggesting severe iron deficiency and confirming that hephaestin plays an important role in body iron acquisition. Consistent with this, the knockout mice accumulated iron in duodenal enterocytes and had reduced intestinal iron absorption. In addition, the similarities of the phenotypes of the whole body and intestine-specific hephaestin knockout mice clarify the important role of hephaestin specifically in intestinal enterocytes in maintaining whole body iron homeostasis. These mouse models will serve as valuable tools to study the role of hephaestin and associated proteins in iron transport in the small intestine and other tissues. PMID:24896847

  7. Enhancing effects of chitosan and chitosan hydrochloride on intestinal absorption of berberine in rats.

    PubMed

    Chen, Wei; Fan, Dongjiao; Meng, Lingkuo; Miao, Yuqiang; Yang, Shenshen; Weng, Yan; He, Haibing; Tang, Xing

    2012-01-01

    Berberine chloride (BBR) is a plant alkaloid that has been used for centuries for treatment of inflammation, dysentery, and liver diseases. It is poorly absorbed from the gastrointestinal (GI) tract and its various clinical uses are limited because of its poor bioavailability. The object of the present study was to investigate the absorption enhancing effect of chitosan on BBR. Mixtures of BBR and chitosan were prepared and the absorption enhancement was investigated in rats. The results showed a dose-dependent absorption enhancement produced by chitosan. Formulations containing 0.5%, 1.5%, and 3.0% chitosan resulted in improvement of AUC(0-36 h) values by 1.9, 2.2, 2.5 times. The absorption enhancing ability of chitosan may be due to its ability to improve the BBR paracellular pathway in the intestinal tract. Chitosan hydrochloride, a salt of chitosan, was also investigated in this study. However, the addition of 2.0% and 3.3% chitosan hydrochloride to BBR solution did not produce any increase in either C(max) or AUC(0-36 h) of BBR. Subsequent solubility studies suggested that the reduced berberine chloride solubility in chitosan hydrochloride may limit the enhancement ability. This study showed that the optimum formulation producing the highest BBR absorption is the BBR solution containing 3.0% chitosan.

  8. 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

  9. 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.

  10. Using iron chelating agents to enhance dermatological PDT

    NASA Astrophysics Data System (ADS)

    Curnow, Alison; Dogra, Yuktee; Winyard, Paul; Campbell, Sandra

    2009-06-01

    Topical protoporphyrin IX (PPIX) induced photodynamic therapy (PDT) of basal cell carcinoma (BCC) produces good clinical outcomes with excellent cosmesis as long as the disease remains superficial. Efficacy for nodular BCC however appears inferior to standard treatment unless repeat treatments are performed. Enhancement is therefore required and is possible by employing iron chelating agents to temporarily increase PPIX accumulation above the levels normally obtained using aminolevulinic acid (ALA) or the methyl ester of ALA (MAL) alone. In vitro studies investigated the effect of the novel iron chelator, CP94 on necrotic or apoptotic cell death in cultured human skin fibroblasts and epidermal carcinoma cells incubated with MAL. Furthermore, following a dose escalating safety study conducted with ALA in patients, an additional twelve nodular BCCs were recruited for topical treatment with standard MAL-PDT +/- increasing doses of CP94. Six weeks later following clinical assessment, the whole treatment site was excised for histological analysis. CP94 produced greater cell death in vitro when administered in conjunction with MAL than this porphyrin precursor could produce when administered alone. Clinically, PDT treatment using Metvix + CP94 was a simple and safe modification associated with a trend of reduced tumor thickness with increasing CP94 dose.

  11. Electrically Tunable Absorption Enhancement with Spectral and Polarization Selectivity through Graphene Plasmonic Light Trapping

    PubMed Central

    Liu, Wenbin; Zhang, Jianfa; Zhu, Zhihong; Yuan, Xiaodong; Qin, Shiqiao

    2016-01-01

    In this paper, anisotropic graphene plasmonic structures are explored for light trapping and absorption enhancement in surrounding media. It is shown that electrically tunable and versatile spectral and polarization selectivity can be realized. Particularly, it is possible to control absorption of the incident light’s polarization component at a specific wavelength by varying the Fermi energy with suitable geometric designs. It may find applications for new types of infrared and THz photodetectors and will promote the research of other novel polarization devices.

  12. Needle Profile Grating Structure for Absorption Enhancement in GaAs Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Wang, Yile; Zhang, Xu; Guo, Minqiang; Sun, Xiaohong; Yu, Yanguang; Xi, Jiangtao

    2015-11-01

    We conduct a systematic study of thin film solar cells consisting of a GaAs needle profile (NP) grating structure as a light-trapping layer. The influence of geometric parameters on the optical absorption of the NP grating is investigated using rigorous coupled wave analysis and the finite element method. This type of structure can lead to broadband optical absorption enhancement throughout the wavelength range that we studied. Our simulation results reveal that the absorption efficiency of NP grating can be improved significantly compared with its rectangular grating counterpart. The proposed structure is expected to illuminate the design and fabrication of high-efficiency solar cells.

  13. Strong enhancement of light absorption and highly directive thermal emission in graphene.

    PubMed

    Pu, Mingbo; Chen, Po; Wang, Yanqin; Zhao, Zeyu; Wang, Changtao; Huang, Cheng; Hu, Chenggang; Luo, Xiangang

    2013-05-20

    Graphene is a two-dimensional material with exotic electronic, optical and thermal properties. The optical absorption in monolayer graphene is limited by the fine structure constant α. Here we demonstrated the strong enhancement of light absorption and thermal radiation in homogeneous graphene. Numerical simulations show that the light absorbance can be controlled from near zero to 100% by tuning the Fermi energy. Moreover, a set of periodically located absorption peaks is observed at near grazing incidence. Based on this unique property, highly directive comb-like thermal radiation at near-infrared frequencies is demonstrated.

  14. Enhanced absorption of graphene strips with a multilayer subwavelength grating structure

    SciTech Connect

    Hu, Jin-Hua; Huang, Yong-Qing Duan, Xiao-Feng; Wang, Qi; Zhang, Xia; Wang, Jun; Ren, Xiao-Min

    2014-12-01

    The optical absorption of graphene strips covered on a multilayer subwavelength grating (MSG) surface is theoretically investigated. The absorption of graphene strips with MSG is enhanced in the wavelength range of 1500 nm to 1600 nm by critical coupling, which is associated with the combined effects of a guided resonance of MSG and its photonic band gap effect. The critical coupling of the graphene strips can be controlled by adjusting the incident angle without changing the structural parameters of MSG. The absorption of graphene strips can also be tuned by varying key parameters, such as grating period, strip width, and incident angle.

  15. Time-Resolved Broadband Cavity-Enhanced Absorption Spectroscopy behind Shock Waves.

    PubMed

    Matsugi, Akira; Shiina, Hiroumi; Oguchi, Tatsuo; Takahashi, Kazuo

    2016-04-07

    A fast and sensitive broadband absorption technique for measurements of high-temperature chemical kinetics and spectroscopy has been developed by applying broadband cavity-enhanced absorption spectroscopy (BBCEAS) in a shock tube. The developed method has effective absorption path lengths of 60-200 cm, or cavity enhancement factors of 12-40, over a wavelength range of 280-420 nm, and is capable of simultaneously recording absorption time profiles over an ∼32 nm spectral bandpass in a single experiment with temporal and spectral resolutions of 5 μs and 2 nm, respectively. The accuracy of the kinetic and spectroscopic measurements was examined by investigating high-temperature reactions and absorption spectra of formaldehyde behind reflected shock waves using 1,3,5-trioxane as a precursor. The rate constants obtained for the thermal decomposition reactions of 1,3,5-trioxane (to three formaldehyde molecules) and formaldehyde (to HCO + H) agreed well with the literature data. High-temperature absorption cross sections of formaldehyde between 280 and 410 nm have been determined at the post-reflected-shock temperatures of 955, 1265, and 1708 K. The results demonstrate the applicability of the BBCEAS technique to time- and wavelength-resolved sensitive absorption measurements at high temperatures.

  16. Evaluation of Chlorella as a Decorporation Agent to Enhance the Elimination of Radioactive Strontium from Body

    PubMed Central

    Ogawa, Kazuma; Fukuda, Tadahisa; Han, Jaegab; Kitamura, Yoji; Shiba, Kazuhiro; Odani, Akira

    2016-01-01

    Background Release of radionuclides, such as 137Cs and 90Sr, into the atmosphere and the ocean presents an important problem because internal exposure to 137Cs and 90Sr could be very harmful to humans. Chlorella has been reported to be effective in enhancing the excretion of heavy metals; thus, we hypothesized that Chlorella could also enhance the elimination of 137Cs or 90Sr from the body. We evaluated the potential of Chlorella as a decorporation agent in vitro and in vivo, using 85Sr instead of 90Sr. Methods In vitro experiments of adsorption of 137Cs and 85Sr to Chlorella were performed under wide pH conditions. The maximum sorption capacity of Chlorella to strontium was estimated using the Langmuir model. A 85Sr solution was orally administrated to mice pretreated with Chlorella. At 48 h after 85Sr administration, the biodistribution of radioactivity was determined. Results In the in vitro experiments, although 85Sr barely adsorbed to Chlorella at low pH, the 85Sr adsorption ratio to Chlorella increased with increasing pH. The maximum sorption capacity of Chlorella to strontium was 9.06 mg / g. 137Cs barely adsorbed to Chlorella under any pH conditions. In the biodistribution experiments, bone accumulation of radioactivity after 85Sr administration was significantly decreased in the Chlorella pretreatment group compared with the non-treatment control group. Conclusions In conclusion, these results indicated that Chlorella could inhibit the absorption of 90Sr into the blood and enhance the elimination of 90Sr from the body through adsorption in intestine. Further studies are required to elucidate the mechanism and the components of Chlorella needed for adsorption to strontium and could promote the development of more effective decorporation agents. PMID:26828430

  17. Design principles for plasmonic thin film GaAs solar cells with high absorption enhancement

    NASA Astrophysics Data System (ADS)

    Hong, Lei; Rusli; Wang, Xincai; Zheng, Hongyu; He, Lining; Xu, Xiaoyan; Wang, Hao; Yu, HongYu

    2012-09-01

    In this paper, a systematic design and analysis of gallium arsenide thin film solar cells incorporated with a periodic silver nanoparticles (NPs) structure to enhance light absorption is presented using the finite element method. The influence of the silver nanoparticles diameter and structure periodicity on light absorption has been examined. It is found that the absorption is significantly enhanced due to the surface plasmon induced by the silver nanoparticles. The optimal structural parameters are achieved when the diameter of the nanoparticles is 200 nm and the periodicity is 444 nm. This gives rise to a maximum ultimate photocurrent of 26.32 mA/cm2 under AM1.5G solar irradiation. In addition, the underlying physics that accounts for the enhancement is discussed.

  18. Enhancing the absorption properties of acoustic porous plates by periodically embedding Helmholtz resonators.

    PubMed

    Groby, J-P; Lagarrigue, C; Brouard, B; Dazel, O; Tournat, V; Nennig, B

    2015-01-01

    This paper studies the acoustical properties of hard-backed porous layers with periodically embedded air filled Helmholtz resonators. It is demonstrated that some enhancements in the acoustic absorption coefficient can be achieved in the viscous and inertial regimes at wavelengths much larger than the layer thickness. This enhancement is attributed to the excitation of two specific modes: Helmholtz resonance in the viscous regime and a trapped mode in the inertial regime. The enhancement in the absorption that is attributed to the Helmholtz resonance can be further improved when a small amount of porous material is removed from the resonator necks. In this way the frequency range in which these porous materials exhibit high values of the absorption coefficient can be extended by using Helmholtz resonators with a range of carefully tuned neck lengths.

  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. Chitosan nanoparticles enhance the intestinal absorption of the green tea catechins (+)-catechin and (-)-epigallocatechin gallate.

    PubMed

    Dube, Admire; Nicolazzo, Joseph A; Larson, Ian

    2010-10-09

    Catechins found in green tea have received considerable attention due to their favourable biological properties which include cardioprotective, neuroprotective and anti-cancer effects. However, their therapeutic potential is limited by their low oral bioavailability, attributed to poor stability and intestinal absorption. We encapsulated (+)-catechin (C) and (-)-epigallocatechin gallate (EGCg) in chitosan nanoparticles (CS NP) as a means of enhancing their intestinal absorption. Using excised mouse jejunum in Ussing chambers, encapsulation significantly enhanced (p<0.05) intestinal absorption. The cumulative amounts transported after encapsulation were significantly higher (p<0.05), i.e. 302.1+/-46.1 vs 206.8+/-12.6ng/cm(2) and 102.7+/-12.4 vs 57.9+/-7.9ng/cm(2) for C and EGCg, respectively. The mechanism by which absorption was enhanced was not through an effect of CS NPs on intestinal paracellular or passive transcellular transport processes (as shown by transport of (14)C-mannitol and (3)H-propranolol) or an effect on efflux proteins (as shown by transport of (3)H-digoxin) but was likely due to stabilization of catechins after encapsulation (99.7+/-0.7 vs 94.9+/-3.8% and 56.9+/-3.0 vs 1.3+/-1.7% of the initial C and EGCg concentration remaining, respectively). This study demonstrates that encapsulation of catechins in CS NPs enhances their intestinal absorption and is a promising strategy for improving their bioavailability.

  1. Enhanced intestinal absorption of daidzein by borneol/menthol eutectic mixture and microemulsion.

    PubMed

    Shen, Qi; Li, Xi; Li, Wenji; Zhao, Xinyi

    2011-12-01

    In the present study, the effect of a borneol/menthol eutectic mixture (25:75) and microemulsion on the absorption of daidzein in rat intestinal membrane was evaluated. The microemulsion formulation was composed of ethyl oleate (oil), Cremophor RH40 (surfactant), PEG400 (co-surfactant), and water. The borneol/menthol eutectic mixture and its microemulsion were found to enhance the intestinal absorption of daidzein in vitro. A diffusion chamber system with isolated rat intestinal membranes was used. In contrast, verapamil (0.3 mM), a typical P-glycoprotein inhibitor, showed no effect on the absorption of daidzein by this system. A pharmacokinetic study was conducted in rats. After oral administration of daidzein at a dose of 10 mg/kg in the form of either borneol/menthol eutectic mixtures or suspension, the relative bioavailability of borneol/menthol eutectic mixtures and microemulsion was enhanced by about 1.5- and 3.65-fold, respectively, compared with a daidzein suspension. In conclusion, a borneol/menthol eutectic mixture can enhance the absorption of daidzein, although the mechanism of absorption enhancement is still unclear.

  2. Quantum-enhanced deliberation of learning agents using trapped ions

    NASA Astrophysics Data System (ADS)

    Dunjko, V.; Friis, N.; Briegel, H. J.

    2015-02-01

    A scheme that successfully employs quantum mechanics in the design of autonomous learning agents has recently been reported in the context of the projective simulation (PS) model for artificial intelligence. In that approach, the key feature of a PS agent, a specific type of memory which is explored via random walks, was shown to be amenable to quantization, allowing for a speed-up. In this work we propose an implementation of such classical and quantum agents in systems of trapped ions. We employ a generic construction by which the classical agents are ‘upgraded’ to their quantum counterparts by a nested process of adding coherent control, and we outline how this construction can be realized in ion traps. Our results provide a flexible modular architecture for the design of PS agents. Furthermore, we present numerical simulations of simple PS agents which analyze the robustness of our proposal under certain noise models.

  3. Broadband absorption enhancement of organic solar cells with interstitial lattice patterned metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Luzhou; Choy, Wallace C. H.; Sha, Wei E. I.

    2013-06-01

    Light blocking induced by top patterned nanostructures is a fundamental limit in solar cells absorption. Here we propose an interstitial lattice patterned organic solar cell which can improve the light blocking of traditional square lattice and achieve broadband absorption enhancement. Compared to square lattice design, the plasmonic mode couplings between individual metallic nanoparticles in the interstitial lattice are more versatile and much stronger. Moreover, plasmonic modes can couple to the guided modes, resulting in large enhancement factor at some wavelengths. The interstitial lattice concept will be a broad interest and great help for high-performance photovoltaics.

  4. [Near infrared Cavity enhanced absorption spectroscopy study of NO2O].

    PubMed

    Wu, Zhi-wei; Dong, Yan-ting; Zhou, Wei-dong

    2014-08-01

    Using a tunable near infrared external cavity diode laser and a 650 mm long high finesse optical cavity consisting of two highly reflective (R=99.97% at 6561.39 cm(-1)) plan-concave mirrors of curvature radius approximately 1000 mm, a cavity enhanced absorption spectroscopy (CEAS) system was made. The absorption spectra centered at 6561.39 cm(-1) of pure N2O gas and gas mixtures of N2O and N2 were recorded. According to the absorption of N2O at 6561.39 cm(-1) in the cavity, the measured effective absorption path was about 1460 km. The spectra line intensity and line-width of N2O centered at 6561.39 cm(-1) were carefully studied. The relationship between the line-width of absorption spectra and the gas pressure was derived. The pressure broadening parameter of N2 gas for NO2O line centered at 6 561. 39 cm(-1) was deduced and given a value of approximately (0.114 +/- 0.004) cm(-1) x atm(-1). The possibility to detect trace N2O gas in mixture using this CEAS system was investigated. By recording the ab- sorption spectra of N2O gas mixtures at different concentration, the relationship between the line intensity and gas concentration was derived. The minimum detectable absorption was found to be 2.34 x 10(-7) cm(-1) using this cavity enhanced absorption spectroscopy system. And te measurement precision in terms of relative standard deviation (RSD) for N2O is approximately 1.73%, indicating the possibility of using the cavity enhanced absorption spectroscopy system for micro gas N2O analysis in the future.

  5. Meaningful interactions can enhance visual discrimination of human agents.

    PubMed

    Neri, Peter; Luu, Jennifer Y; Levi, Dennis M

    2006-09-01

    The ability to interpret and predict other people's actions is highly evolved in humans and is believed to play a central role in their cognitive behavior. However, there is no direct evidence that this ability confers a tangible benefit to sensory processing. Our quantitative behavioral experiments show that visual discrimination of a human agent is influenced by the presence of a second agent. This effect depended on whether the two agents interacted (by fighting or dancing) in a meaningful synchronized fashion that allowed the actions of one agent to serve as predictors for the expected actions of the other agent, even though synchronization was irrelevant to the visual discrimination task. Our results demonstrate that action understanding has a pervasive impact on the human ability to extract visual information from the actions of other humans, providing quantitative evidence of its significance for sensory performance.

  6. Mechanism of optical absorption enhancement in thin film organic solar cells with plasmonic metal nanoparticles.

    PubMed

    Qu, Di; Liu, Fang; Huang, Yidong; Xie, Wanlu; Xu, Qi

    2011-11-21

    The optical absorption enhancement in thin film organic solar cells (OSCs) with plasmonic metal nanoparticles (NPs) has been studied by means of finite element method with a three-dimension model. It is found that significant plasmonic enhancement of above 100% can be obtained by introducing Ag-NPs at the interface between P3HT:PCBM active layer and PEDOT:PSS anode layer. This enhancement is even larger than that with Ag-NPs totally embedded in the P3HT:PCBM active layer of thin film OSCs. Furthermore, the enhancement mechanism of Ag-NPs at different positions of thin film OSCs is investigated.

  7. One-Step Solvothermal Synthesis of Black TiO2 Films for Enhanced Visible Absorption.

    PubMed

    Chen, Shanlong; Tao, Jie; Tao, Haijun; Wang, Chen; Shen, Yizhou; Jiang, Jiajia; Zhu, Lumin; Zeng, Xiaofei; Wang, Tao

    2016-03-01

    An economic and facile solvothermal method was reported to prepare black TiO2 films on Ti foils that possessed the property of optical absorption in the visible region. The UV-vis spectra showed that the black TiO2 samples exhibited highly enhanced visible-light absorption from 400-600 nm. The black TiO2 films were compact and uniform, composed of nanoparticles and nanosheets. Moreover, a mixed structure of anatase and rutile was present in black TiO2 films. The electron paramagnetic resonance (EPR) spectra confirmed the presence of Ti3+ in samples, which accounted for longer wavelength optical absorption. The results showed that the TiO2 films had retained their black color upon storage in ambient atmosphere for more than one month. Therefore, it was supposed that the ethylene glycol in solvothermal reaction was the key factor for the extension of the absorption spectrum.

  8. Absorption enhancement using photonic crystals for silicon thin film solar cells.

    PubMed

    Park, Yeonsang; Drouard, Emmanuel; El Daif, Ounsi; Letartre, Xavier; Viktorovitch, Pierre; Fave, Alain; Kaminski, Anne; Lemiti, Mustapha; Seassal, Christian

    2009-08-03

    We propose a design that increases significantly the absorption of a thin layer of absorbing material such as amorphous silicon. This is achieved by patterning a one-dimensional photonic crystal (1DPC) in this layer. Indeed, by coupling the incident light into slow Bloch modes of the 1DPC, we can control the photon lifetime and then, enhance the absorption integrated over the whole solar spectrum. Optimal parameters of the 1DPC maximize the integrated absorption in the wavelength range of interest, up to 45% in both S and P polarization states instead of 33% for the unpatterned, 100 nm thick amorphous silicon layer. Moreover, the absorption is tolerant with respect to fabrication errors, and remains relatively stable if the angle of incidence is changed.

  9. Broadband short-range surface plasmon structures for absorption enhancement in organic photovoltaics.

    PubMed

    Bai, Wenli; Gan, Qiaoqiang; Song, Guofeng; Chen, Lianghui; Kafafi, Zakya; Bartoli, Filbert

    2010-11-08

    We theoretically demonstrate a polarization-independent nanopatterned ultra-thin metallic structure supporting short-range surface plasmon polariton (SRSPP) modes to improve the performance of organic solar cells. The physical mechanism and the mode distribution of the SRSPP excited in the cell device were analyzed, and reveal that the SRSPP-assisted broadband absorption enhancement peak could be tuned by tailoring the parameters of the nanopatterned metallic structure. Three-dimensional finite-difference time domain calculations show that this plasmonic structure can enhance the optical absorption of polymer-based photovoltaics by 39% to 112%, depending on the nature of the active layer (corresponding to an enhancement in short-circuit current density by 47% to 130%). These results are promising for the design of organic photovoltaics with enhanced performance.

  10. Supercontinuum high-speed cavity-enhanced absorption spectroscopy for sensitive multispecies detection.

    PubMed

    Werblinski, Thomas; Lämmlein, Bastian; Huber, Franz J T; Zigan, Lars; Will, Stefan

    2016-05-15

    Cavity-enhanced absorption spectroscopy is promising for many applications requiring a very high concentration sensitivity but often accompanied by low temporal resolution. In this Letter, we demonstrate a broadband cavity-enhanced absorption spectrometer capable of detection rates of up to 50 kHz, based on a spatially coherent supercontinuum (SC) light source and an in-house-built, high-speed near-infrared spectrograph. The SC spectrometer allows for the simultaneous quantitative detection of CO2, C2H2, and H2O within a spectral range from 1420 to 1570 nm. Using cavity mirrors with a specified reflectivity of R=98.0±0.3% a minimal spectrally averaged absorption coefficient of αmin=1·10-5  cm-1 can be detected at a repetition rate of 50 kHz.

  11. Enhanced Spin-Orbit Torque via Modulation of Spin Current Absorption.

    PubMed

    Qiu, Xuepeng; Legrand, William; He, Pan; Wu, Yang; Yu, Jiawei; Ramaswamy, Rajagopalan; Manchon, Aurelien; Yang, Hyunsoo

    2016-11-18

    The magnitude of spin-orbit torque (SOT), exerted to a ferromagnet (FM) from an adjacent heavy metal (HM), strongly depends on the amount of spin current absorbed in the FM. We exploit the large spin absorption at the Ru interface to manipulate the SOTs in HM/FM/Ru multilayers. While the FM thickness is smaller than its spin dephasing length of 1.2 nm, the top Ru layer largely boosts the absorption of spin currents into the FM layer and substantially enhances the strength of SOT acting on the FM. Spin-pumping experiments induced by ferromagnetic resonance support our conclusions that the observed increase in the SOT efficiency can be attributed to an enhancement of the spin-current absorption. A theoretical model that considers both reflected and transmitted mixing conductances at the two interfaces of FM is developed to explain the results.

  12. Numerical study of plasmonic absorption enhancement in semiconductor absorbers by metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Hornich, Julian; Pflaum, Christoph; Brabec, Christoph; Forberich, Karen

    2016-09-01

    We are studying the influence of spherical silver nanoparticles (AgNP) in absorbing media by numerically solving the Maxwell's equations. Our simulations show that the near-field absorption enhancement introduced by a single AgNP in the surrounding medium is increasing with the growing particle diameter. However, we observe that the relative absorption per particle volume is on a similar level for different particle sizes; hence, different numbers of particles with the same total volume yield the same near-field absorption enhancement. We also investigate the effect of non-absorbing shells around the AgNP with the conclusion that even very thin shells suppress the beneficial effects of the particles noticeably. Additionally, we include AgNP in an organic solar cell at different vertical positions with different particle spacings and observe the beneficial effects for small AgNP and the scattering dependent performance for larger particles.

  13. Radiative absorption enhancements due to the mixing state of atmospheric black carbon

    SciTech Connect

    Cappa, Christopher D.; Onasch, Timothy B.; Massoli, Paola; Worsnop, Douglas R.; Bates, Timothy S.; Cross, Eben S.; Davidovits, Paul; Hakala, Jani; Hayden, Katherine; Jobson, Bertram Thomas; Kolesar, K. R.; Lack, D. A.; Lerner, Brian M.; Li, Shao-Meng; Mellon, Daniel; Nuaaman, Ibraheem; Olfert, Jason; Petaja, Tuukka; Quinn, P. K.; Song, Chen; Subramanian, R.; Williams, Eric; Zaveri, Rahul A.

    2012-08-30

    Atmospheric particulate black carbon (BC) leads to warming of the Earth's climate. Many models that include forcing by BC assume that non-BC aerosol species internally mixed with BC enhance BC absorption, often by a factor of {approx}2. However, such model estimates have yet to be clearly validated through atmospheric observations. Here, we report on direct measurements of the absorption enhancement (Eabs) of BC in the atmosphere around California and find that it is negligible at 532 nm and much smaller than predicted from theoretical calculations that are uniquely constrained by observations, suggesting that the warming by BC may be significantly overestimated (factor of 2) in many climate models. Additionally, non-BC particulate matter is found to contribute {approx}10% to the total absorption at 405 nm.

  14. Enhanced Spin-Orbit Torque via Modulation of Spin Current Absorption

    NASA Astrophysics Data System (ADS)

    Qiu, Xuepeng; Legrand, William; He, Pan; Wu, Yang; Yu, Jiawei; Ramaswamy, Rajagopalan; Manchon, Aurelien; Yang, Hyunsoo

    2016-11-01

    The magnitude of spin-orbit torque (SOT), exerted to a ferromagnet (FM) from an adjacent heavy metal (HM), strongly depends on the amount of spin current absorbed in the FM. We exploit the large spin absorption at the Ru interface to manipulate the SOTs in HM /FM /Ru multilayers. While the FM thickness is smaller than its spin dephasing length of 1.2 nm, the top Ru layer largely boosts the absorption of spin currents into the FM layer and substantially enhances the strength of SOT acting on the FM. Spin-pumping experiments induced by ferromagnetic resonance support our conclusions that the observed increase in the SOT efficiency can be attributed to an enhancement of the spin-current absorption. A theoretical model that considers both reflected and transmitted mixing conductances at the two interfaces of FM is developed to explain the results.

  15. Significant light absorption enhancement in silicon thin film tandem solar cells with metallic nanoparticles.

    PubMed

    Cai, Boyuan; Li, Xiangping; Zhang, Yinan; Jia, Baohua

    2016-05-13

    Enhancing the light absorption in microcrystalline silicon bottom cell of a silicon-based tandem solar cell for photocurrent matching holds the key to achieving the overall solar cell performance breakthroughs. Here, we present a concept for significantly improving the absorption of both subcells simultaneously by simply applying tailored metallic nanoparticles both on the top and at the rear surfaces of the solar cells. Significant light absorption enhancement as large as 56% has been achieved in the bottom subcells. More importantly the thickness of the microcrystalline layer can be reduced by 57% without compromising the optical performance of the tandem solar cell, providing a cost-effective strategy for high performance tandem solar cells.

  16. Enhanced light absorption in graphene via a liquid-crystalline optical diode

    NASA Astrophysics Data System (ADS)

    Pantazi, Aikaterini Iria; Yannopapas, Vassilios

    2016-09-01

    We demonstrate theoretically that light absorption in graphene can be boosted via a light-trapping mechanism based on a liquid-crystalline optical diode. The optical diode consists of twisted-nematic and nematic liquid-crystalline slabs. In particular, we show that, using a proper optical-diode setup, the absorption in a single graphene layer can be enhanced by a factor of four. By varying the pitch of the twisted-nematic liquid-crystalline slabs comprising the diode, one can tune the operating spectral region of the diode and thus enhance the absorption of graphene within a desired spectral window. Our calculations are based on Berreman's 4×4 method which treats anisotropic, isotropic and/ or inhomogeneous layered systems on equal footing.

  17. Enhancement of the absorption of CO{sub 2} in alkaline buffer solutions: Joint action of two enhancers

    SciTech Connect

    Vazquez, G.; Chenlo, F.; Pereira, G.; Vazquez, P.

    1999-05-01

    The authors measured the absorption of CO{sub 2} in alkaline 0.5 M/0.5 M sodium carbonate/bicarbonate buffers containing either saccharose and sodium arsenite or saccharose and formaldehyde. Absorption enhancement increased upon increasing the concentration of either of the catalysts, but the joint action of the two was always less than the sum of their individual effects, the difference being a function of the acidities and concentrations of the catalysts and the pH of the carbonate/bicarbonate buffer solution

  18. FDTD/TDSE study of surface-enhanced infrared absorption by metal nanoparticles.

    SciTech Connect

    Chang, S.-H.; Schatz, G. C.; Gray, S. K.; Chemistry; Northwestern Univ.; National Cheng-Kung Univ.

    2006-01-01

    We study surface-enhanced infrared absorption, including multiphoton processes, due to the excitation of surface plasmons on metal nanoparticles. The time-dependent Schroedinger equation and finite-difference time-domain method are self-consistently coupled to treat the problem.

  19. Orange but not apple juice enhances ferrous fumarate absorption in small children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ferrous fumarate is a common, inexpensive iron form increasingly used instead of ferrous sulfate as a food iron supplement. However, few data exist as to whether juices enhance iron absorption from ferrous fumarate. We studied 21 children, ages 4.0 to 7.9 years using a randomized crossover design. S...

  20. Dielectric core-shell optical antennas for strong solar absorption enhancement.

    PubMed

    Yu, Yiling; Ferry, Vivian E; Alivisatos, A Paul; Cao, Linyou

    2012-07-11

    We demonstrate a new light trapping technique that exploits dielectric core-shell optical antennas to strongly enhance solar absorption. This approach can allow the thickness of active materials in solar cells lowered by almost 1 order of magnitude without scarifying solar absorption capability. For example, it can enable a 70 nm thick hydrogenated amorphous silicon (a-Si:H) thin film to absorb 90% of incident solar radiation above the bandgap, which would otherwise require a thickness of 400 nm in typical antireflective coated thin films. This strong enhancement arises from a controlled optical antenna effect in patterned core-shell nanostructures that consist of absorbing semiconductors and nonabsorbing dielectric materials. This core-shell optical antenna benefits from a multiplication of enhancements contributed by leaky mode resonances (LMRs) in the semiconductor part and antireflection effects in the dielectric part. We investigate the fundamental mechanism for this enhancement multiplication and demonstrate that the size ratio of the semiconductor and the dielectric parts in the core-shell structure is key for optimizing the enhancement. By enabling strong solar absorption enhancement, this approach holds promise for cost reduction and efficiency improvement of solar conversion devices, including solar cells and solar-to-fuel systems. It can generally apply to a wide range of inorganic and organic active materials. This dielectric core-shell antenna can also find applications in other photonic devices such as photodetectors, sensors, and solid-state lighting diodes.

  1. Angle-tunable enhanced infrared reflection absorption spectroscopy via grating-coupled surface plasmon resonance.

    PubMed

    Petefish, Joseph W; Hillier, Andrew C

    2014-03-04

    Surface enhanced infrared absorption (SEIRA) spectroscopy is an attractive method for increasing the prominence of vibrational modes in infrared spectroscopy. To date, the majority of reports associated with SEIRA utilize localized surface plasmon resonance from metal nanoparticles to enhance electromagnetic fields in the region of analytes. Limited work has been performed using propagating surface plasmons as a method for SEIRA excitation. In this report, we demonstrate angle-tunable enhancement of vibrational stretching modes associated with a thin poly(methyl methacrylate) (PMMA) film that is coupled to a silver-coated diffraction grating. Gratings are fabricated using laser interference lithography to achieve precise surface periodicities, which can be used to generate surface plasmons that overlap with specific vibrational modes in the polymer film. Infrared reflection absorption spectra are presented for both bare silver and PMMA-coated silver gratings at a range of angles and polarization states. In addition, spectra were obtained with the grating direction oriented perpendicular and parallel to the infrared source in order to isolate plasmon enhancement effects. Optical simulations using the rigorous coupled-wave analysis method were used to identify the origin of the plasmon-induced enhancement. Angle-dependent absorption measurements achieved signal enhancements of more than 10-times the signal in the absence of the plasmon.

  2. Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments

    PubMed Central

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Levy Zamora, Misti; Zeng, Limin; Shao, Min; Wu, Yu-Sheng; Zheng, Jun; Wang, Yuan; Glen, Crystal R.; Collins, Donald R.; Molina, Mario J.; Zhang, Renyi

    2016-01-01

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries. PMID:27035993

  3. Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments.

    PubMed

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Levy Zamora, Misti; Zeng, Limin; Shao, Min; Wu, Yu-Sheng; Zheng, Jun; Wang, Yuan; Glen, Crystal R; Collins, Donald R; Molina, Mario J; Zhang, Renyi

    2016-04-19

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

  4. Enhanced photon absorption in spiral nanostructured solar cells using layered 2D materials.

    PubMed

    Tahersima, Mohammad H; Sorger, Volker J

    2015-08-28

    Recent investigations of semiconducting two-dimensional (2D) transition metal dichalcogenides have provided evidence for strong light absorption relative to its thickness attributed to high density of states. Stacking a combination of metallic, insulating, and semiconducting 2D materials enables functional devices with atomic thicknesses. While photovoltaic cells based on 2D materials have been demonstrated, the reported absorption is still just a few percent of the incident light due to their sub-wavelength thickness leading to low cell efficiencies. Here we show that taking advantage of the mechanical flexibility of 2D materials by rolling a molybdenum disulfide (MoS(2))/graphene (Gr)/hexagonal boron nitride stack to a spiral solar cell allows for optical absorption up to 90%. The optical absorption of a 1 μm long hetero-material spiral cell consisting of the aforementioned hetero stack is about 50% stronger compared to a planar MoS(2) cell of the same thickness; although the volumetric absorbing material ratio is only 6%. A core-shell structure exhibits enhanced absorption and pronounced absorption peaks with respect to a spiral structure without metallic contacts. We anticipate these results to provide guidance for photonic structures that take advantage of the unique properties of 2D materials in solar energy conversion applications.

  5. Whey protein hydrolysates enhance water absorption in the perfused small intestine of anesthetized rats.

    PubMed

    Ito, Kentaro; Yamaguchi, Makoto; Noma, Teruyuki; Yamaji, Taketo; Itoh, Hiroyuki; Oda, Munehiro

    2016-08-01

    We evaluated the effect of whey protein hydrolysates (WPH) on the water absorption rate in the small intestine using a rat small intestine perfusion model. The rate was significantly higher with 5 g/L WPH than with 5 g/L soy protein hydrolysates or physiological saline (p < 0.05). WPH dose-dependently increased the water absorption rate in the range of 1.25-10.0 g/L. WPH showed a significantly higher rate than an amino acid mixture whose composition was equal to that of WPH (p < 0.05). The addition of 4-aminomethylbenzoic acid, an inhibitor of PepT1, significantly suppressed WPH's enhancement of water absorption (p < 0.05). The rate of water absorption was significantly correlated with that of peptides/amino acids absorption in WPH (r = 0.82, p < 0.01). These data suggest that WPH have a high water absorption-promoting effect, to which PepT1 contributes.

  6. Enhancement of light absorption in organic solar cells by using plasmonic gratings

    NASA Astrophysics Data System (ADS)

    Xiao, Xiao; Zhang, Zhiyou; Xie, Shiwei; Liu, Yu; Zhai, Yucui; Hu, Dejiao; Du, Jinglei

    2014-11-01

    Organic solar cells show a commercially viable future duo to their inherent advantages, such as light weight, flexibility, and so on. Recently, a lot of progress has been made in every domain of organic solar cells. Among these, plasmonic light trapping is regarded as a promising light management technology for improving the light absorption in organic active layer. In this work, we numerically investigate the light enhancement in organic solar cell by embedding metal gratings as electrodes, including the anode and cathode. The absorption enhancement mechanism is analyzed, and the effects of grating parameters and incident angle are also investigated systematically. The results show the plasmonic gratings, especially the bottom grating, have an obvious improvement for light harvesting in organic layer, and an optical enhancement factor about 100% is obtained.

  7. Lipid-associated oral delivery: Mechanisms and analysis of oral absorption enhancement.

    PubMed

    Rezhdo, Oljora; Speciner, Lauren; Carrier, Rebecca

    2016-10-28

    The majority of newly discovered oral drugs are poorly water soluble, and co-administration with lipids has proven effective in significantly enhancing bioavailability of some compounds with low aqueous solubility. Yet, lipid-based delivery technologies have not been widely employed in commercial oral products. Lipids can impact drug transport and fate in the gastrointestinal (GI) tract through multiple mechanisms including enhancement of solubility and dissolution kinetics, enhancement of permeation through the intestinal mucosa, and triggering drug precipitation upon lipid emulsion depletion (e.g., by digestion). The effect of lipids on drug absorption is currently not quantitatively predictable, in part due to the multiple complex dynamic processes that can be impacted by lipids. Quantitative mechanistic analysis of the processes significant to lipid system function and overall impact on drug absorption can aid in the understanding of drug-lipid interactions in the GI tract and exploitation of such interactions to achieve optimal lipid-based drug delivery. In this review, we discuss the impact of co-delivered lipids and lipid digestion on drug dissolution, partitioning, and absorption in the context of the experimental tools and associated kinetic expressions used to study and model these processes. The potential benefit of a systems-based consideration of the concurrent multiple dynamic processes occurring upon co-dosing lipids and drugs to predict the impact of lipids on drug absorption and enable rational design of lipid-based delivery systems is presented.

  8. Dioscin enhances methotrexate absorption by down-regulating MDR1 in vitro and in vivo

    SciTech Connect

    Wang, Lijuan; Wang, Changyuan; Peng, Jinyong; Liu, Qi; Meng, Qiang; Sun, Huijun; Huo, Xiaokui; and others

    2014-06-01

    The purpose of this study was to investigate the enhancing effect of dioscin on the absorption of methotrexate (MTX) and clarify the molecular mechanism involved in vivo and in vitro. Dioscin increased MTX chemosensitivity and transepithelial flux in the absorptive direction, significantly inhibiting multidrug resistance 1 (MDR1) mRNA and protein expression and MDR1 promoter and nuclear factor κ-B (NF-κB) activities in Caco-2 cells. Moreover, inhibitor κB-α (IκB-α) degradation was inhibited by dioscin. Dioscin enhanced the intracellular concentration of MTX by down-regulating MDR1 expression through a mechanism that involves NF-κB signaling pathway inhibition in Caco-2 cells. Dioscin strengthened MTX absorption by inhibiting MDR1 expression in rat intestine. In addition, even though MTX is absorbed into the enterocytes, there was no increase in toxicity observed, and that, in fact, decreased toxicity was seen. - Highlights: • Dioscin raised MTX concentration by inhibiting MDR1 in Caco-2 cells. • Dioscin suppresses MDR1 by inhibiting NF-κB signaling pathway in Caco-2 cells. • Dioscin can enhance MTX absorption via inhibiting MDR1 in vivo and in vitro. • Dioscin did not increase MTX-induced gastrointestinal mucosal toxicity.

  9. Absorptivity of molded soil-improving agents based on brown coals and zeolites

    SciTech Connect

    Aleksandrov, I.V.; Kossov, I.I.

    1993-12-31

    The objective of this work was to create a new technique for producing molded soil-improving agents based on brown coal from the Adunchulun deposit, and to determine the soil-improving properties of the obtained compositions.

  10. Enhancement of near-infrared absorption in graphene with metal gratings

    SciTech Connect

    Zhao, B.; Zhang, Z. M.; Zhao, J. M.

    2014-07-21

    Graphene has been demonstrated as a good candidate for ultrafast optoelectronic devices. However, graphene is essentially transparent in the visible and near infrared with an absorptivity of 2.3%, which has largely limited its application in photon detection. This Letter demonstrates that the absorptance in a monatomic graphene layer can be greatly enhanced to nearly 70%, thanks to the localized strong electric field resulting from magnetic resonances in deep metal gratings. Furthermore, the resonance frequency is essentially not affected by the additional graphene layer. The method presented here may benefit the design of next-generation graphene-based optical and optoelectronic devices.

  11. Non-degenerate two photon absorption enhancement for laser dyes by precise lock-in detection

    SciTech Connect

    Xue, B.; Katan, C.; Bjorgaard, J. A.; Kobayashi, T.

    2015-12-15

    This study demonstrates a measurement system for a non-degenerate two-photon absorption (NDTPA) spectrum. The NDTPA light sources are a white light super continuum beam (WLSC, 500 ∼ 720 nm) and a fundamental beam (798 nm) from a Ti:Sapphire laser. A reliable broadband NDTPA spectrum is acquired in a single-shot detection procedure using a 128-channel lock-in amplifier. The NDTPA spectra for several common laser dyes are measured. Two photon absorption cross section enhancements are found in the experiment and validated by theoretical calculation for all of the chromophores.

  12. Recent Progress Towards Quantum Dot Solar Cells with Enhanced Optical Absorption.

    PubMed

    Zheng, Zerui; Ji, Haining; Yu, Peng; Wang, Zhiming

    2016-12-01

    Quantum dot solar cells, as a promising candidate for the next generation solar cell technology, have received tremendous attention in the last 10 years. Some recent developments in epitaxy growth and device structures have opened up new avenues for practical quantum dot solar cells. Unfortunately, the performance of quantum dot solar cells is often plagued by marginal photon absorption. In this review, we focus on the recent progress made in enhancing optical absorption in quantum dot solar cells, including optimization of quantum dot growth, improving the solar cells structure, and engineering light trapping techniques.

  13. Refractive index enhancement with vanishing absorption in short, high-density vapor cells

    NASA Astrophysics Data System (ADS)

    Simmons, Z. J.; Proite, N. A.; Miles, J.; Sikes, D. E.; Yavuz, D. D.

    2012-05-01

    It has recently been predicted and experimentally demonstrated that the refractive index of a vapor may be enhanced while maintaining vanishing absorption by using the interference of two Raman transitions, one absorptive and one amplifying in nature. In this paper, we present a detailed experimental study of this technique in a 1-mm-long rubidium (Rb) vapor cell with densities exceeding 1014 cm-3. We study the optimization of the achieved refractive index as various experimental parameters are varied and discuss a number of limitations of the current experiments. We also present a detailed discussion of possible experimental improvements and future prospects of this technique.

  14. Absorption modulation enhancement of Azo-polymer film induced by plasmonic field

    NASA Astrophysics Data System (ADS)

    Wang, Xiangxian; Zhang, Douguo; Fu, Qiang; Ming, Hai; Wu, Wenxuan; Zhang, Qijin

    2012-11-01

    A thin photochromic film on top of the resist layer can be used as a virtual mask to fabricate super-resolution lithography patterns. In this letter, based on the azobenzene polymer, the absorption intensity of the 365nm LED is effectively modulated by 532nm laser, the modulation degree reaches to 87%.When the silver nanocubes are dropped onto the surface of the polymer film, the modulation degree is significantly higher than that without the nanoparticles in the same intensity of 532nm laser due to the field enhancement of excitation of surface plasmons. The absorption modulation features of the polymer film are favorable for the further smaller line width nanolithography.

  15. Recent Progress Towards Quantum Dot Solar Cells with Enhanced Optical Absorption

    NASA Astrophysics Data System (ADS)

    Zheng, Zerui; Ji, Haining; Yu, Peng; Wang, Zhiming

    2016-05-01

    Quantum dot solar cells, as a promising candidate for the next generation solar cell technology, have received tremendous attention in the last 10 years. Some recent developments in epitaxy growth and device structures have opened up new avenues for practical quantum dot solar cells. Unfortunately, the performance of quantum dot solar cells is often plagued by marginal photon absorption. In this review, we focus on the recent progress made in enhancing optical absorption in quantum dot solar cells, including optimization of quantum dot growth, improving the solar cells structure, and engineering light trapping techniques.

  16. Method and apparatus for enhanced detection of toxic agents

    DOEpatents

    Greenbaum, Elias [Knoxville, TN; Rodriguez, Jr., Miguel; Wu, Jie Jayne [Knoxville, TN; Qi, Hairong [Knoxville, TN

    2012-06-12

    A water quality analyzer for real-time detection according to the invention comprises a biased AC electro-osmosis (ACEO) cell for receiving a fluid to be analyzed having a plurality photosynthetic organisms therein, and concentrating the plurality photosynthetic organisms into at least one concentrated region. A photodetector is provided for obtaining a measured photosynthetic activity of the plurality of photosynthetic organisms in the concentrated region, wherein chemical, biological or radiological agents reduce a nominal photosynthetic activity of the photosynthetic organisms. An electronics package analyzes the measured photosynthetic activity to indicate a presence of the chemical, biological or radiological agents in the fluid.

  17. Gold nanoparticle based surface enhanced fluorescence for detection of organophosphorus agents

    NASA Astrophysics Data System (ADS)

    Dasary, Samuel S. R.; Rai, Uma S.; Yu, Hongtao; Anjaneyulu, Yerramilli; Dubey, Madan; Ray, Paresh Chandra

    2008-07-01

    Organophosphorus agents (OPA) represent a serious concern to public safety as nerve agents and pesticides. Here we report the development of gold nanoparticle based surface enhanced fluorescence (NSEF) spectroscopy for rapid and sensitive screening of organophosphorus agents. Fluorescent from Eu 3+ ions that are bound within the electromagnetic field of gold nanoparticles exhibit a strong enhancement. In the presence of OPA, Eu 3+ ions are released from the gold nanoparticle surface and thus a very distinct fluorescence signal change was observed. We discussed the mechanism of fluorescence enhancement and the role of OPA for fluorescence intensity change in the presence of gold nanoparticles.

  18. Nanostructured enhanced chemical sensing surfaces for mid-IR molecular absorption

    NASA Astrophysics Data System (ADS)

    Dunbar, L. A.; Threlfall, E.; Eckert, R.; Angeloni, S.; Stanley, R. P.

    2013-01-01

    Enhanced transmissions at infra-red wavelengths are measured through hole arrays made in gold-covered silicon nitride free-standing membranes. The membranes are made by a standard photolithography batch process. They are cheap to fabricate, reproducible and robust. The optical transmission of the membranes are investigated with varying hole size (down to 1μm), period, and thickness. The membranes show enhanced optical transmission. The spectra show good agreement with a very simple mode matching model which can be used for design. Calculations are also shown giving absorption enhancements of 5.7 normalized to the same material on a silicon membrane. Finite difference time domain calculations are also presented to show the spatial distribution of the enhanced field. Field enhancements of 3.3 are calculated. The field enhancements are concentrated in the hole which makes the membranes ideally suited for a microfluidic setup. Hence, this paper shows that through enhanced transmission cheap, disposable membranes in a simplified transmission can be used for measurements for molecular absorption.

  19. Enhancement of commercial antifungal agents by kojic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Kojic acid (KA), a natural by-product of fungal fermentation, is a commonly used food and cosmetic additive. We show that KA increases activity of amphotericin B and strobilurin, medical and agricultural antifungal agents, respectively, possibly targeting the fungal antioxidative system. KA shows pr...

  20. An inulin-type fructan enhances calcium absorption primarily via an effect on colonic absorption in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium absorption efficiency and bone mineral mass are increased in adolescents who regularly consume inulin-type fructans (ITF). The mechanism of action in increasing absorption is unknown but may be related to increased colonic calcium absorption. We conducted a study in young adults designed to ...

  1. Ultrabroadband, More than One Order Absorption Enhancement in Graphene with Plasmonic Light Trapping

    PubMed Central

    Xiong, Feng; Zhang, Jianfa; Zhu, Zhihong; Yuan, Xiaodong; Qin, Shiqiao

    2015-01-01

    This paper presents an comprehensive study of light trapping and absorption enhancement in graphene through metallic plasmonic structures and shows a strategy to realize both ultrabroadband and strong absorption enhancement. Three different plasmonic absorber designs are investigated by numerical simulations. The excitation of localized plasmons in the metallic structures significantly enhances the interactions between graphene and light at the resonances. By employing a splitted cross design for plasmonic resonant antennas and integrating two types of sub-antennas with different sizes, more than 30% of optical absorption in monolayer graphene is realized in a ultrabroad spectral range from 780 to 1760 nm. This enhancement functionality can be translated to any wavelength band from ultraviolet to terahertz ranges by modifying the geometric design of the plasmonic structure and can be applied for other two dimensional materials and their heterogeneous structures. It may significantly improve the efficiency of optical devices such as broadband photodetectors and solar cells based on graphene and other two-dimensional materials. PMID:26582477

  2. Gas trace detection with cavity enhanced absorption spectroscopy: a review of its process in the field

    NASA Astrophysics Data System (ADS)

    Liu, Siqi; Luo, Zhifu; Tan, Zhongqi; Long, Xingwu

    2016-11-01

    Cavity-enhanced absorption spectroscopy (CEAS) is a technology in which the intracavity absorption is deduced from the intensity of light transmitted by the high finesse optical cavity. Then the samples' parameters, such as their species, concentration and absorption cross section, would be detection. It was first proposed and demonstrated by Engeln R. [1] and O'Keefe[2] in 1998. This technology has extraordinary detection sensitivity, high resolution and good practicability, so it is used in many fields , such as clinical medicine, gas detection and basic physics research. In this paper, we focus on the use of gas trace detection, including the advance of CEAS over the past twenty years, the newest research progresses, and the prediction of this technology's development direction in the future.

  3. Sensitive and rapid laser diagnostic for shock tube kinetics studies using cavity-enhanced absorption spectroscopy.

    PubMed

    Sun, Kai; Wang, Shengkai; Sur, Ritobrata; Chao, Xing; Jeffries, Jay B; Hanson, Ronald K

    2014-04-21

    We report the first application of cavity-enhanced absorption spectroscopy (CEAS) using a coherent light source for sensitive and rapid gaseous species time-history measurements in a shock tube. Off-axis alignment and fast scanning of the laser wavelength were used to minimize coupling noise in a low-finesse cavity. An absorption gain factor of 83 with a measurement time resolution of 20 µs was demonstrated for C2H2 detection using a near-infrared transition near 1537 nm, corresponding to a noise-equivalent detection limit of 20 ppm at 296 K and 76 ppm at 906 K at 50 kHz. This substantial gain in signal, relative to conventional single-pass absorption, will enable ultra-sensitive species detection in shock tube kinetics studies, particularly useful for measurements of minor species and for studies of dilute reactive systems.

  4. Enhanced risk management by an emerging multi-agent architecture

    NASA Astrophysics Data System (ADS)

    Lin, Sin-Jin; Hsu, Ming-Fu

    2014-07-01

    Classification in imbalanced datasets has attracted much attention from researchers in the field of machine learning. Most existing techniques tend not to perform well on minority class instances when the dataset is highly skewed because they focus on minimising the forecasting error without considering the relative distribution of each class. This investigation proposes an emerging multi-agent architecture, grounded on cooperative learning, to solve the class-imbalanced classification problem. Additionally, this study deals further with the obscure nature of the multi-agent architecture and expresses comprehensive rules for auditors. The results from this study indicate that the presented model performs satisfactorily in risk management and is able to tackle a highly class-imbalanced dataset comparatively well. Furthermore, the knowledge visualised process, supported by real examples, can assist both internal and external auditors who must allocate limited detecting resources; they can take the rules as roadmaps to modify the auditing programme.

  5. Fluctuation-Enhanced Sensing for Biological Agent Detection and Identification

    DTIC Science & Technology

    2009-01-01

    introduced for gas sensing [1-3,5-7], the principle allows virtually the sensing of any chemical or physical agent. In the case of gas sensing, the...Dept. of Experimental Physics , Dom ter 9, Szeged, H-6720, Hungary (email: gingl@physx.u-szeged.hu). C.G. Granqvist is with Uppsala University, Angstrom...corresponding classical sensing scheme cannot be used. ii) Rule of thumb: The usual sensor signal, which is the average value of a physical quantity, has

  6. Liquid cultivation techniques for enhancing the effectiveness of yeast biocontrol agents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biocontrol agents will gain broader acceptance into integrated pest management programs if products with enhanced efficacy and consistency of performance are developed. Though given comparatively little research attention, liquid cultivation environments and protocols can and should be optimized to...

  7. Multi-phase functionalization of titanium for enhanced photon absorption in the vis-NIR region

    PubMed Central

    Thakur, Pooja; Tan, Bo; Venkatakrishnan, Krishnan

    2015-01-01

    Inadequate absorption of Near Infrared (NIR) photons by conventional silicon solar cells has been a major stumbling block towards the attainment of a high efficiency “full spectrum” solar cell. An effective enhancement in the absorption of such photons is desired as they account for a considerable portion of the tappable solar energy. In this work, we report a remarkable gain observed in the absorption of photons in the near infrared and visible region (400 nm–1000 nm) by a novel multi-phased oxide of titanium. Synthesised via a single step ultra-fast laser pulse interaction with pure titanium, characterisation studies have identified this oxide of titanium to be multi-phased and composed of Ti3O, (TiO.716)3.76 and TiO2 (rutile). Computed to have an average band gap value of 2.39 eV, this ultrafast laser induced multi-phased titanium oxide has especially exhibited steady absorption capability in the NIR range of 750–1000 nm, which to the best of our knowledge, was never reported before. The unique NIR absorption properties of the laser functionalised titanium coupled with the simplicity and versatility of the ultrafast laser interaction process involved thereby provides tremendous potential towards the photon sensitization of titanium and thereafter for the inception of a “full spectrum” solar device. PMID:26477578

  8. Enhanced Reverse Saturable Absorption and Optical Limiting in Heavy-Atom Substituted Phthalocyanines

    NASA Technical Reports Server (NTRS)

    Perry, J. W.; Mansour, K.; Marder, S. R.; Alvarez, D., Jr.; Perry, K. J.; Choong, I.

    1994-01-01

    The reverse saturable absorption and optical limiting response of metal phthalocyaninies can be enhanced by using the heavy-atom effect. Phthalocyanines containing heavy metal atoms, such as In, Sn, and Pb show nearly a factor of two enhancement in the ratio of effective excited-state to ground-state absorption cross sections compared to those containing lighter atoms, such as Al and Si. In an f/8 optical geometry, homogeneous solutions of heavy metal phthalocyanines, at 30% linear transmission, limit 8-ns, 532-nm laser pulses to less than or equal to 3 (micro)J (the energy for 50% probability of eye damage) for incident pulses up to 800 (micro)J.

  9. Cascading metallic gratings for broadband absorption enhancement in ultrathin plasmonic solar cells

    SciTech Connect

    Wen, Long; Sun, Fuhe; Chen, Qin

    2014-04-14

    The incorporation of plasmonic nanostructures in the thin-film solar cells (TFSCs) is a promising route to harvest light into the nanoscale active layer. However, the light trapping scheme based on the plasmonic effects intrinsically presents narrow-band resonant enhancement of light absorption. Here we demonstrate that by cascading metal nanogratings with different sizes atop the TFSCs, broadband absorption enhancement can be realized by simultaneously exciting multiple localized surface plasmon resonances and inducing strong coupling between the plasmonic modes and photonic modes. As a proof of concept, we demonstrate of 66.5% in the photocurrent in an ultrathin amorphous silicon TFSC with two-dimensional cascaded gratings over the reference cell without gratings.

  10. Performance Enhancement of Polymer Solar Cells by Using Two Polymer Donors with Complementary Absorption Spectra.

    PubMed

    Lu, Heng; Zhang, Xuejuan; Li, Cuihong; Wei, Hedi; Liu, Qian; Li, Weiwei; Bo, Zhishan

    2015-07-01

    Performance enhancement of polymer solar cells (PSCs) is achieved by expanding the absorption of the active layer of devices. To better match the spectrum of solar radiation, two polymers with different band gaps are used as the donor material to fabricate ternary polymer cells. Ternary blend PSCs exhibit an enhanced short-circuit current density and open-circuit voltage in comparison with the corresponding HD-PDFC-DTBT (HD)- and DT-PDPPTPT (DPP)-based binary polymer solar cells, respectively. Ternary PSCs show a power conversion efficiency (PCE) of 6.71%, surpassing the corresponding binary PSCs. This work demonstrates that the fabrication of ternary PSCs by using two polymers with complementary absorption is an effective way to improve the device performance.

  11. Strongly Enhanced Laser Absorption and Electron Acceleration via Resonant Excitation of Surface Plasma Waves

    NASA Astrophysics Data System (ADS)

    Raynaud, M.; Riconda, C.; Adam, J. C.; Heron, A.

    2010-02-01

    The possibility of creating enhanced fast electron bunches via the excitation of surface plasma waves (SPW) in laser overdense plasma interaction has been investigated by mean of relativistic one dimension motion of a test electron in the field of the surface plasma wave study and with two-dimensional (2D) Particle-In-Cell (PIC) numerical simulations. Strong electron acceleration together with a dramatic increase, up to 70%, of light absorption by the plasma is observed.

  12. Light absorption enhancement in heterostructure organic solar cells through the integration of 1-D plasmonic gratings.

    PubMed

    Zilio, Pierfrancesco; Sammito, Davide; Zacco, Gabriele; Mazzeo, Marco; Gigli, Giuseppe; Romanato, Filippo

    2012-07-02

    The integration of a plasmonic lamellar grating in a heterostructure organic solar cell as a light trapping mechanism is investigated with numerical Finite Elements simulations. A global optimization of all the geometric parameters has been performed. The obtained wide-band enhancement in optical absorption is correlated with both the propagating and the localized plasmonic modes of the structure, which have been identified and characterized in detail.

  13. Enhancements of the Andreev conductance due to emission/absorption of bosonic quanta.

    PubMed

    Barański, J; Domański, T

    2015-08-05

    We predict that the subgap spectrum and transport properties of the quantum dot embedded between superconducting and metallic reservoirs can be substantially enhanced by emission/absorption of external bosonic quanta. Upon tuning the gate voltage the in-gap Andreev states eventually interfere with each other. We explore the measurable signatures of such interference appearing in the differential conductance for both linear and nonlinear regimes.

  14. IR absorption and surface-enhanced Raman spectra of the isoquinoline alkaloid berberine

    NASA Astrophysics Data System (ADS)

    Strekal', N. D.; Motevich, I. G.; Nowicky, J. W.; Maskevich, S. A.

    2007-01-01

    We present the IR absorption and surface-enhanced Raman scattering (SERS) spectra of the isoquinoline alkaloid berberine adsorbed on a silver hydrosol and on the surface of a silver electrode for different potentials. Based on quantum chemical calculations, for the first time we have assigned the vibrations in the berberine molecule according to vibrational mode. The effect of the potential of the silver electrode on the geometry of sorption of the molecule on the surface is considered, assuming a short-range mechanism for enhancement of Raman scattering.

  15. Enhancement of light in tissue using hyper-osmotic agents

    NASA Astrophysics Data System (ADS)

    Zaman, Raiyan T.; Chen, Bo; Parthasarathy, Ashwin B.; Estrada, Arnold D., Jr.; Ponticorvo, Ardien; Rylander, Henry G., III; Dunn, Andrew K.; Welch, Ashley J.

    2008-02-01

    Optical changes in skin blood flow due to the presence of glycerol were measured from a two-dimensional map of blood flow in skin blood vessels with a dynamic imaging technique using laser speckle. In this study a dorsal skin-flap window was implanted on the hamster skin with and without a hyper-osmotic agent i.e. glycerol. The hyper-osmotic drug was delivered to the skin through the open dermal end of the window model. A two-dimensional map of blood flow in skin blood vessels were obtained with very high spatial and temporal resolution by imaging the speckle pattern with a CCD camera. Preliminary studies demonstrated that hyper-osmotic agents such as glycerol not only make tissue temporarily translucent, but also reduce blood flow. The blood perfusion was measured every 3 minutes up to 36-60 minutes after diffusion of anhydrous glycerol. Small capillaries blood flow reduced significantly within 3-9 minutes. Perfusion rate in lager blood vessels i.e. all arteries and some veins decreased (speckle contrasts increased from 0.0115 to 0.384) over time. However, the blood flow in some veins reduced significantly in 36 minutes. After 24 hours the blood perfusion further reduced in capillaries. However, the blood flow increased in larger blood vessels in 24 hours compared to an hour after application of glycerol. For further investigation the speckle contrast measurement were verified with color Doppler optical coherence tomography.

  16. Enhanced gastrointestinal absorption of N3- O-toluyl-fluorouracil by cationic solid lipid nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Donghua; Liu, Chunxi; Zou, Weiwei; Zhang, Na

    2010-03-01

    This study was aimed to prepare N3- O-toluyl-fluorouracil (TFu) loaded cationic solid lipid nanoparticles (TFu-SLNs) and evaluate the potential of a novel lipid-based drug delivery system to enhance the oral absorption of TFu. TFu-SLNs were prepared by the film dispersion-ultrasonication method, using hexadecyltrimethylammonium bromide as cationic tenside. The formulation and manufacture parameters were optimized concerning the drug encapsulation efficiency and the particle size. The in vitro release characteristics, in vivo pharmacokinetic properties and bioavailability, and in situ intestinal absorption features were investigated. The morphology of TFu-SLNs was approximately spherical and the mean particle size was 178.8 ± 9.99 nm; the zeta potential was +19.54 ± 0.32 mV. The mean entrapment efficiency and drug loading were 71.03 ± 1.19% and 3.57 ± 0.08%, respectively. The release behaviors of TFu from TFu-SLNs in PBS were fitted to the bioexponential model, while in artificial gastric juice, artificial intestinal juice and artificial gastric juice (2 h) followed by artificial intestinal juice (2-48 h) were fitted to the Weibull equation. The results of the pharmacokinetic studies in mice showed that the bioavailability of TFu-SLNs was significantly increased compared with that of the TFu suspensions after oral administration. The absorption of TFu-SLNs in intestine of rat was fitted to first-order kinetics with passive diffusion mechanism and the main segments of TFu-SLNs absorbed in intestine were duodenum and jejunum for the bioadhesion mediated by electrostatic interaction between the positively charged colloidal particles and the negatively charged mucosal surface. These results indicated that cationic SLNs would offer a promising delivery system for the facilitation of the bioavailability of poorly oral absorption drugs by enhancing the bioadhesion between the absorption mucosal surface and the drug carriers.

  17. Development of contrast enhancing agents in magnetic resonance imaging.

    PubMed

    Lex, L

    1989-01-01

    Magnetic Resonance Imaging (MRI) is a powerful new diagnostic tool in medicine. In MRI there is a great need to improve the specific identification of different tissues i.e. to enhance the contrast between them. This review tries to cover most of the approaches known for solving this problem.

  18. Linking enhanced deposition agent functionality with aesthetic performance.

    PubMed

    Erazo-Majewicz, Paquita; Roberts-Howard, Cathleen; Oldham, Eugene; Lynch, Craig; Graham, John; Usher, Courtney R; Joneja, Surendra

    2011-01-01

    This study examines the cationic polymers 1) guar hydroxypropyltrimonium chloride polymers (GHPTC), 2) acrylamidopropyltrimonium chloride/acrylamide copolymer (APTAC/Acm), 3) polyquaternium polymers (PQ-10, PQ-7, PQ-67), and 4) a new polymer system approach for their a) deposition efficiency (as measured by quantifying oils deposited on virgin hair) and b) ability to deliver good wet and dry lubricity to the hair from a cleansing formulation as measured by comb energy and friction characteristics of the hair samples. Conditioning polymer technology approaches 1) acrylamidopropyltrimonium chloride/acrylamide copolymer, 2) a guar hydroxypropyltrimonium chloride polymer, and 3) the new polymer system approach deliver superior deposition of natural conditioning oils and dimethicone materials from anionic/amphoteric surfactant cleansing formulations. These new polymer technologies offer formulators the ability to improve uniformity of deposition as well as deposition efficiency of conditioning agents onto hair, and target the desired hair lubricity.

  19. Omnidirectional and broadband absorption enhancement from trapezoidal Mie resonators in semiconductor metasurfaces

    PubMed Central

    Pala, Ragip A.; Butun, Serkan; Aydin, Koray; Atwater, Harry A.

    2016-01-01

    Light trapping in planar ultrathin-film solar cells is limited due to a small number of optical modes available in the thin-film slab. A nanostructured thin-film design could surpass this limit by providing broadband increase in the local density of states in a subwavelength volume and maintaining efficient coupling of light. Here we report a broadband metasurface design, enabling efficient and broadband absorption enhancement by direct coupling of incoming light to resonant modes of subwavelengthscale Mie nanoresonators defined in the thin-film active layer. Absorption was investigated both theoretically and experimentally in prototypes consisting of lithographically patterned, two-dimensional periodic arrays of silicon nanoresonators on silica substrates. A crossed trapezoid resonator shape of rectangular cross section is used to excite broadband Mie resonances across visible and near-IR spectra. Our numerical simulations, optical absorption measurements and photocurrent spectral response measurements demonstrate that crossed trapezoidal Mie resonant structures enable angle-insensitive, broadband absorption. A short circuit current density of 12.0 mA/cm2 is achieved in 210 nm thick patterned Si films, yielding a 4-fold increase compared to planar films of the same thickness. It is suggested that silicon metasurfaces with Mie resonator arrays can provide useful insights to guide future ultrathin-film solar cell designs incorporating nanostructured thin active layers. PMID:27641965

  20. Cavity-enhanced measurements of hydrogen peroxide absorption cross sections from 353 to 410 nm.

    PubMed

    Kahan, Tara F; Washenfelder, Rebecca A; Vaida, Veronica; Brown, Steven S

    2012-06-21

    We report near-ultraviolet and visible absorption cross sections of hydrogen peroxide (H(2)O(2)) using incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS), a recently developed, high-sensitivity technique. The measurements reported here span the range of 353-410 nm and extend published electronic absorption cross sections by 60 nm to absorption cross sections below 1 × 10(-23) cm(2) molecule(-1). We have calculated photolysis rate constants for H(2)O(2) in the lower troposphere at a range of solar zenith angles by combining the new measurements with previously reported data at wavelengths shorter than 350 nm. We predict that photolysis at wavelengths longer than those included in the current JPL recommendation may account for up to 28% of the total hydroxyl radical (OH) production from H(2)O(2) photolysis under some conditions. Loss of H(2)O(2) via photolysis may be of the same order of magnitude as reaction with OH and dry deposition in the lower atmosphere; these processes have very different impacts on HO(x) loss and regeneration.

  1. ENHANCED ABSORPTION OF MILLIMETER WAVE ENERGY IN MURINE SUBCUTANEOUS BLOOD VESSELS

    PubMed Central

    Alekseev, Stanislav I.; Ziskin, Marvin C.

    2011-01-01

    The aim of the present study was to determine millimeter wave (MMW) absorption by blood vessels traversing the subcutaneous fat layer of murine skin. Most calculations were performed using the finite-difference time-domain (FDTD) technique. We used two types of models: (1) a rectangular block of multilayer tissue with blood vessels traversing the fat layer and (2) cylindrical models with circular and elliptical cross sections simulating the real geometry of murine limbs. We found that the specific absorption rate (SAR) in blood vessels normally traversing the fat layer achieved its maximal value at the parallel orientation of the E-field to the vessel axis. At 42 GHz exposure, the maximal SAR in small blood vessels could be more than 30 times greater than that in the skin. The SAR increased with decreasing the blood vessel diameter and increasing the fat thickness. The SAR decreased with increasing the exposure frequency. When the cylindrical or elliptical models of murine limbs were exposed to plane MMW, the greatest absorption of MMW energy occurred in blood vessels located on the lateral areas of the limb model. At these areas the maximal SAR values were comparable with or were greater than the maximal SAR on the front surface of the skin. Enhanced absorption of MMW energy by blood vessels traversing the fat layer may play a primary role in initiating MMW effects on blood cells and vasodilatation of cutaneous blood vessels. PMID:21344460

  2. Proliposome powders for enhanced intestinal absorption and bioavailability of raloxifene hydrochloride: effect of surface charge.

    PubMed

    Velpula, Ashok; Jukanti, Raju; Janga, Karthik Yadav; Sunkavalli, Sharath; Bandari, Suresh; Kandadi, Prabhakar; Veerareddy, Prabhakar Reddy

    2013-12-01

    The primary goal of the present study was to investigate the combined prospective of proliposomes and surface charge for the improved oral delivery of raloxifene hydrochloride (RXH). Keeping this objective, the present systematic study was focused to formulate proliposomes by varying the ratio of hydrogenated soyphosphatidylcholine and cholesterol. Furthermore, to assess the role of surface charge on improved absorption of RXH, anionic and cationic vesicles were prepared using dicetyl phosphate and stearylamine, respectively. The formulations were characterized for size, zeta potential and entrapment efficiency. The improved dissolution characteristics assessed from dissolution efficiency, mean dissolution rate were higher for proliposome formulations. The solid state characterization studies indicate the transformation of native crystalline form of the drug to amorphous and/or molecular state. The higher effective permeability coefficient and fraction absorbed in humans extrapolated from in situ single-pass intestinal absorption study data in rats provide an insight on the potential of proliposomes and cationic surface charge for augment in absorption across gastro intestinal barrier. To draw the conclusions, in vivo pharmacokinetic study carried out in rats indicate a threefold enhancement in the rate and extent of absorption of RXH from cationic proliposome formulation which unfurl the potential of proliposomes and role of cationic charge for improved oral delivery of RXH.

  3. Enhanced Absorption in 2D Materials Via Fano- Resonant Photonic Crystals

    SciTech Connect

    Wang, Wenyi; Klotz, Andrey; Yang, Yuanmu; Li, Wei; Kravchenko, Ivan I.; Briggs, Dayrl P.; Bolotin, Kirill; Valentine, Jason

    2015-05-01

    The use of two-dimensional (2D) materials in optoelectronics has attracted much attention due to their fascinating optical and electrical properties. For instance, graphenebased devices have been employed for applications such as ultrafast and broadband photodetectors and modulators while transition metal dichalcogenide (TMDC) based photodetectors can be used for ultrasensitive photodetection. However, the low optical absorption of 2D materials arising from their atomic thickness limits the maximum attainable external quantum efficiency. For example, in the visible and NIR regimes monolayer MoS2 and graphene absorb only ~10% and 2.3% of incoming light, respectively. Here, we experimentally demonstrate the use of Fano-resonant photonic crystals to significantly boost absorption in atomically thin materials. Using graphene as a test bed, we demonstrate that absorption in the monolayer thick material can be enhanced to 77% within the telecommunications band, the highest value reported to date. We also show that the absorption in the Fano-resonant structure is non-local, with light propagating up to 16 μm within the structure. This property is particularly beneficial in harvesting light from large areas in field-effect-transistor based graphene photodetectors in which separation of photo-generated carriers only occurs ~0.2 μm adjacent to the graphene/electrode interface.

  4. Wafer-scale metasurface for total power absorption, local field enhancement and single molecule Raman spectroscopy.

    PubMed

    Wang, Dongxing; Zhu, Wenqi; Best, Michael D; Camden, Jon P; Crozier, Kenneth B

    2013-10-04

    The ability to detect molecules at low concentrations is highly desired for applications that range from basic science to healthcare. Considerable interest also exists for ultrathin materials with high optical absorption, e.g. for microbolometers and thermal emitters. Metal nanostructures present opportunities to achieve both purposes. Metal nanoparticles can generate gigantic field enhancements, sufficient for the Raman spectroscopy of single molecules. Thin layers containing metal nanostructures ("metasurfaces") can achieve near-total power absorption at visible and near-infrared wavelengths. Thus far, however, both aims (i.e. single molecule Raman and total power absorption) have only been achieved using metal nanostructures produced by techniques (high resolution lithography or colloidal synthesis) that are complex and/or difficult to implement over large areas. Here, we demonstrate a metasurface that achieves the near-perfect absorption of visible-wavelength light and enables the Raman spectroscopy of single molecules. Our metasurface is fabricated using thin film depositions, and is of unprecedented (wafer-scale) extent.

  5. Enhanced Absorption in 2D Materials Via Fano- Resonant Photonic Crystals

    DOE PAGES

    Wang, Wenyi; Klotz, Andrey; Yang, Yuanmu; ...

    2015-05-01

    The use of two-dimensional (2D) materials in optoelectronics has attracted much attention due to their fascinating optical and electrical properties. For instance, graphenebased devices have been employed for applications such as ultrafast and broadband photodetectors and modulators while transition metal dichalcogenide (TMDC) based photodetectors can be used for ultrasensitive photodetection. However, the low optical absorption of 2D materials arising from their atomic thickness limits the maximum attainable external quantum efficiency. For example, in the visible and NIR regimes monolayer MoS2 and graphene absorb only ~10% and 2.3% of incoming light, respectively. Here, we experimentally demonstrate the use of Fano-resonant photonicmore » crystals to significantly boost absorption in atomically thin materials. Using graphene as a test bed, we demonstrate that absorption in the monolayer thick material can be enhanced to 77% within the telecommunications band, the highest value reported to date. We also show that the absorption in the Fano-resonant structure is non-local, with light propagating up to 16 μm within the structure. This property is particularly beneficial in harvesting light from large areas in field-effect-transistor based graphene photodetectors in which separation of photo-generated carriers only occurs ~0.2 μm adjacent to the graphene/electrode interface.« less

  6. Enhanced absorption of millimeter wave energy in murine subcutaneous blood vessels.

    PubMed

    Alekseev, Stanislav I; Ziskin, Marvin C

    2011-09-01

    The aim of the present study was to determine millimeter wave (MMW) absorption by blood vessels traversing the subcutaneous fat layer of murine skin. Most calculations were performed using the finite-difference time-domain (FDTD) technique. We used two types of models: (1) a rectangular block of multilayer tissue with blood vessels traversing the fat layer and (2) cylindrical models with circular and elliptical cross-sections simulating the real geometry of murine limbs. We found that the specific absorption rate (SAR) in blood vessels normally traversing the fat layer achieved its maximal value at the parallel orientation of the E-field to the vessel axis. At 42 GHz exposure, the maximal SAR in small blood vessels could be more than 30 times greater than that in the skin. The SAR increased with decreasing the blood vessel diameter and increasing the fat thickness. The SAR decreased with increasing the exposure frequency. When the cylindrical or elliptical models of murine limbs were exposed to plane MMW, the greatest absorption of MMW energy occurred in blood vessels located on the lateral areas of the limb model. At these areas the maximal SAR values were comparable with or were greater than the maximal SAR on the front surface of the skin. Enhanced absorption of MMW energy by blood vessels traversing the fat layer may play a primary role in initiating MMW effects on blood cells and vasodilatation of cutaneous blood vessels.

  7. Broadband absorption enhancement achieved by optical layer mediated plasmonic solar cell.

    PubMed

    Ren, Wenzhen; Zhang, Guanghui; Wu, Yukun; Ding, Huaiyi; Shen, Qinghe; Zhang, Kun; Li, Junwen; Pan, Nan; Wang, Xiaoping

    2011-12-19

    We propose a novel thin solar cell design, integrating plasmonic component with optical layer, for conspicuous performance improvement in organic (P3HT: PCBM) thin film solar cell. Despite the relatively simple structure, the designed solar cell can get strikingly high spectral performance with the short circuit current density (J(sc)) enhancement up to 67%; and a nicely large J(sc) enhancement over 50% can be easily obtained spanning rather a broad geometric parametric range. The mechanisms responsible for this significant and broadband absorption enhancement as well as the effects of intercalating a plasmonic nanoparticles (NPs) array and an optical layer are theoretically and systematically investigated by finite-difference time-domain calculations (FDTD). The origin of the dramatically increased absorption is believed to be the synergistic effect between 1) the enhanced electric field and forward scattering upon excitation of localized surface plasmon resonance (LSPR) of the NPs, and 2) the favorable redistributions of light field in the device due to the beneficial interference effect mediated by the optical layer. Such a design concept is quite versatile and can be easily extended to other thin film solar cell systems.

  8. Colonic absorption of salmon calcitonin using tetradecyl maltoside (TDM) as a permeation enhancer.

    PubMed

    Petersen, Signe Beck; Nielsen, Lisette Gammelgaard; Rahbek, Ulrik Lytt; Guldbrandt, Mette; Brayden, David J

    2013-03-12

    Calcitonin is used as a second line treatment of postmenopausal osteoporosis, but widespread acceptance is somewhat limited by subcutaneous and intranasal routes of delivery. This study attempted to enable intestinal sCT absorption in rats using the mild surfactant, tetradecyl maltoside (TDM) as an intestinal permeation enhancer. Human Caco-2 and HT29-MTX-E12 mucus-covered intestinal epithelial monolayers were used for permeation studies. Rat in situ intestinal instillation studies were conducted to evaluate the absorption of sCT with and without 0.1 w/v% TDM in jejunum, ileum and colon. TDM significantly enhanced sCT permeation across intestinal epithelial monolayers, most likely due to combined paracellular and transcellular actions. In situ, TDM caused an increased absolute bioavailability of sCT in rat colon from 1.0% to 4.6%, whereas no enhancement increase was observed in ileal and jejunal instillations. Histological analysis suggested mild perturbation of colonic epithelia in segments instilled with sCT and TDM. These data suggest that the membrane composition of the colon is different to the small intestine and that it is more amenable to permeation enhancement. Thus, formulations designed to release payload in the colon could be advantageous for systemic delivery of poorly permeable molecules.

  9. Near infrared cavity enhanced absorption spectra of atmospherically relevant ether-1, 4-Dioxane

    NASA Astrophysics Data System (ADS)

    Chandran, Satheesh; Varma, Ravi

    2016-01-01

    1, 4-Dioxane (DX) is a commonly found ether in industrially polluted atmosphere. The near infrared absorption spectra of this compound has been recorded in the region 5900-8230 cm- 1 with a resolution of 0.08 cm- 1 using a novel Fourier transform incoherent broadband cavity-enhanced absorption spectrometer (FT-IBBCEAS). All recorded spectra were found to contain regions that are only weakly perturbed. The possible combinations of fundamental modes and their overtone bands corresponding to selected regions in the measured spectra are tabulated. Two interesting spectral regions were identified as 5900-6400 cm- 1 and 8100-8230 cm- 1. No significant spectral interference due to presence of water vapor was observed suggesting the suitability of these spectral signatures for spectroscopic in situ detection of DX. The technique employed here is much more sensitive than standard Fourier transform spectrometer measurements on account of long effective path length achieved. Hence significant enhancement of weaker absorption lines above the noise level was observed as demonstrated by comparison with an available measurement from database.

  10. Absorption Enhancement in "Giant" Core/Alloyed-Shell Quantum Dots for Luminescent Solar Concentrator.

    PubMed

    Zhao, Haiguang; Benetti, Daniele; Jin, Lei; Zhou, Yufeng; Rosei, Federico; Vomiero, Alberto

    2016-10-01

    Luminescent solar concentrators (LSCs) can potentially reduce the cost of solar cells by decreasing the photoactive area of the device and boosting the photoconversion efficiency (PCE). This study demonstrates the application of "giant" CdSe/Cdx Pb1-x S core/shell quantum dots (QDs) as light harvesters in high performance LSCs with over 1.15% PCE. Pb addition is critical to maximize PCE. First, this study synthesizes "giant" CdSe/Cdx Pb1-x S QDs with high quantum yield (40%), narrow size distribution (<10%), and stable photoluminescence in a wide temperature range (100-300 K). Subsequently these thick alloyed-shell QDs are embedded in a polymer matrix, resulting in a highly transparent composite with absorption spectrum covering the range 300-600 nm, and are applied as active material for prototype LSCs. The latter exhibits a 15% enhancement in efficiency with respect to 1% PCE of the pure-CdS-shelled QDs. This study attributes this increase to the contribution of Pb doping. The results demonstrate a straightforward approach to enhance light absorption in "giant" QDs by metal doping, indicating a promising route to broaden the absorption spectrum and increase the efficiency of LSCs.

  11. Enhanced Solar Energy Absorption by Internally-mixed Black Carbon in Snow Grains

    SciTech Connect

    Flanner, M. G.; Liu, Xiaohong; Zhou, Cheng; Penner, Joyce E.; Jiao, C.

    2012-05-30

    Here we explore light absorption by snowpack containing black carbon (BC) particles residing within ice grains. Basic considerations of particle volumes and BC/snow mass concentrations show that there are generally 0:05-109 BC particles for each ice grain. This suggests that internal BC is likely distributed as multiple inclusions within ice grains, and thus the dynamic effective medium approximation (DEMA) (Chylek and Srivastava, 1983) is a more appropriate optical representation for BC/ice composites than coated-sphere or standard mixing approximations. DEMA calculations show that the 460 nm absorption cross-section of BC/ice composites, normalized to the mass of BC, is typically enhanced by factors of 1.8-2.1 relative to interstitial BC. BC effective radius is the dominant cause of variation in this enhancement, compared with ice grain size and BC volume fraction. We apply two atmospheric aerosol models that simulate interstitial and within-hydrometeor BC lifecycles. Although only {approx}2% of the atmospheric BC burden is cloud-borne, 71-83% of the BC deposited to global snow and sea-ice surfaces occurs within hydrometeors. Key processes responsible for within-snow BC deposition are development of hydrophilic coatings on BC, activation of liquid droplets, and subsequent snow formation through riming or ice nucleation by other species and aggregation/accretion of ice particles. Applying deposition fields from these aerosol models in offline snow and sea-ice simulations, we calculate that 32-73% of BC in global surface snow resides within ice grains. This fraction is smaller than the within-hydrometeor deposition fraction because meltwater flux preferentially removes internal BC, while sublimation and freezing within snowpack expose internal BC. Incorporating the DEMA into a global climate model, we simulate increases in BC/snow radiative forcing of 43-86%, relative to scenarios that apply external optical properties to all BC. We show that snow metamorphism

  12. Dual functions of gold nanorods as photothermal agent and autofluorescence enhancer to track cell death during plasmonic photothermal therapy.

    PubMed

    Kannadorai, Ravi Kumar; Chiew, Geraldine Giap Ying; Luo, Kathy Qian; Liu, Quan

    2015-02-01

    Gold nanorods have the potential to localize the treatment procedure by hyperthermia and influence the fluorescence. The longitudinal plasmon peak contributes to the photothermal effect by converting light to heat. When these nanorods are PEGylated, it not only makes it biocompatible but also acts as a spacer layer during fluorescence enhancement. When the PEGylated nanorods are internalized inside the cells through endocytosis, the transverse plasmonic peak combined with the enhanced absorption and scattering properties of the nanorods can enhance the autofluorescence emission intensity from the cell. The autofluorescence from the mitochondria inside cells which reflects the respiratory status of the cell was enhanced two times by the presence of nanorods within the cell. At four minutes, the nanorods incubated cells reached the hyperthermic temperature when illuminated continuously with near infrared laser. The cell viability test and autofluorescence intensity curve showed a similar trend indicating the progress of cell death over time. This is the first report to the best of our knowledge to suggest the potential of exploiting the dual capabilities of gold nanorods as photothermal agents and autofluorescence enhancer to track cell death.

  13. Enhancement of light absorption in polyazomethines due to plasmon excitation on randomly distributed metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Wróbel, P.; Antosiewicz, T. J.; Stefaniuk, T.; Ciesielski, A.; Iwan, A.; Wronkowska, A. A.; Wronkowski, A.; Szoplik, T.

    2015-05-01

    In photovoltaic devices, metal nanoparticles embedded in a semiconductor layer allow the enhancement of solar-toelectric energy conversion efficiency due to enhanced light absorption via a prolonged optical path, enhanced electric fields near the metallic inclusions, direct injection of hot electrons, or local heating. Here we pursue the first two avenues. In the first, light scattered at an angle beyond the critical angle for reflection is coupled into the semiconductor layer and confined within such planar waveguide up to possible exciton generation. In the second, light is trapped by the excitation of localized surface plasmons on metal nanoparticles leading to enhanced near-field plasmon-exciton coupling at the peak of the plasmon resonance. We report on results of a numerical experiment on light absorption in polymer- (fullerene derivative) blends, using the 3D FDTD method, where exact optical parameters of the materials involved are taken from our recent measurements. In simulations we investigate light absorption in randomly distributed metal nanoparticles dispersed in polyazomethine-(fullerene derivative) blends, which serve as active layers in bulkheterojunction polymer solar cells. In the study Ag and Al nanoparticles of different diameters and fill factors are diffused in two air-stable aromatic polyazomethines with different chemical structures (abbreviated S9POF and S15POF) mixed with phenyl-C61-butyric acid methyl ester (PCBM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The mixtures are spin coated on a 100 nm thick Al layer deposited on a fused silica substrate. Optical constants of the active layers are taken from spectroscopic ellipsometry and reflectance measurements using a rotating analyzer type ellipsometer with auto-retarder performed in the wavelength range from 225 nm to 2200 nm. The permittivities of Ag and Al particles of diameters from 20 to 60 nm are assumed to be equal to those measured on 100 to 200 nm thick metal films.

  14. Optical absorption enhancement of hybrid-plasmonic-based metal-semiconductor-metal photodetector incorporating metal nanogratings and embedded metal nanoparticles.

    PubMed

    Tan, Chee Leong; Karar, Ayman; Alameh, Kamal; Lee, Yong Tak

    2013-01-28

    We propose and numerically demonstrate a high absorption hybrid-plasmonic-based metal semiconductor metal photodetector (MSM-PD) comprising metal nanogratings, a subwavelength slit and amorphous silicon or germanium embedded metal nanoparticles (NPs). Simulation results show that by optimizing the metal nanograting parameters, the subwavelength slit and the embedded metal NPs, a 1.3 order of magnitude increase in electric field is attained, leading to 28-fold absorption enhancement, in comparison with conventional MSM-PD structures. This is 3.5 times better than the absorption of surface plasmon polariton (SPP) based MSM-PD structures employing metal nanogratings and a subwavelength slit. This absorption enhancement is due to the ability of the embedded metal NPs to enhance their optical absorption and scattering properties through light-stimulated resonance aided by the conduction electrons of the NPs.

  15. Enhanced ileal absorption of a hydrophilic macromolecule, pentosan polysulfate sodium (PPS).

    PubMed

    Dong, Liang; Yum, Alicia; Nguyen, Joe; Wong, Pat

    2004-01-01

    An in situ gelling, bioadhesive liquid formulation was developed to enhance the bioavailbility (BA) of a polysaccharide, pentosan polysulfate sodium (PPS). The formulation was tested to determine its bioavailability enhancement in a non-flush/non-ligated rat ileal model. A potent synergistic effect was found with a gelling agent Cremophor and a permeation enhancer sodium salicylate. The absolute bioavailabilities were 1.9%, 4.6%, 6.3% and 46.4%, respectively, for the PPS solution in saline, sodium salicylate/PPS, Cremophor/PPS and Cremophor/sodium salicylate/PPS. Therefore, we successfully demonstrated the approach of utilizing an in situ gelling/bioadhesive liquid carrier to enhancing the bioavailability of a hydrophilic macromolecule at the distal small intestine.

  16. Mo doping-enhanced dye absorption of Bi2Se3 nanoflowers

    PubMed Central

    2013-01-01

    A simple solvothermal approach is explored to prepare Bi2−xMoxSe3 nanostructures by employing N,N-dimethylformamide (DMF) as the solvent. Mo plays an important role in the assembly of the Bi2−xMoxSe3 nanostructures from nanoplates to nanoflowers. Structural and morphological studies indicate that the resulting products are large specific surface area single-crystalline Bi2−xMoxSe3 nanoflowers self-assembled from thin nanoplates during the reaction process. The absorption properties of the as-prepared samples are investigated with Rhodamine B (RhB) as dye, and it is found that the Bi1.85Mo0.15Se3 nanoflowers show an optimal adsorption capacity, implying that Mo doping not only changes the morphologies of the nanostructures but also enhances their absorption behaviors. PMID:24172176

  17. Optical absorption enhancement in 3D nanofibers coated on polymer substrate for photovoltaic devices.

    PubMed

    Kiani, Amirkianoosh; Venkatakrishnan, Krishnan; Tan, Bo

    2015-06-01

    Recent research in the field of photovoltaics has shown that polymer solar cells have great potential to provide low-cost, lightweight and flexible electronic devices to harvest solar energy. In this paper, we propose a new method for the generation of three-dimensional nanofibers coated on polymer substrate induced by femtosecond laser pulses. In this new method, a thin layer of polymer is irradiated by megahertz femtosecond laser pulses under ambient conditions, and a thin fibrous layer is generated on top of the polymer substrate. This method is single step; no additional materials are added, and the layers of the three-dimensional (3D) polymer nanofibrous structures are grown on top of the substrate after laser irradiation. Light spectroscopy results show significant enhancement of light absorption in the generated 3D nanofibrous layers of polymer. Finally, we suggest how to maximize the light trapping and optical absorption of the generated nanofiber cells by optimizing the laser parameters.

  18. Surface-enhanced infrared absorption studies towards a new optical biosensor

    PubMed Central

    Stäb, Julia; Adam, Jennifer T; Gauglitz, Günter

    2016-01-01

    Reflectometric interference spectroscopy (RIfS), which is well-established in the visual regime, measures the optical thickness change of a sensitive layer caused, e.g., by binding an analyte. When operated in the mid-infrared range the sensor provides additional information via weak absorption spectra (fingerprints). The originally poor spectra are magnified by surface-enhanced infrared absorption (SEIRA). This is demonstrated using the broad complex fluid water band at 3300 cm−1, which is caused by superposition of symmetric, antisymmetric stretching vibration, and the first overtone of the bending vibration under the influence of H-bonds and Fermi resonance effect. The results are compared with a similar experiment performed with an ATR (attenuated total reflectance) set-up. PMID:28144523

  19. Enhanced optical absorption and electric field resonance in diabolo metal bar optical antennas.

    PubMed

    Pan, Zeyu; Guo, Junpeng

    2013-12-30

    Resonance behaviors of the fundamental resonance mode of diabolo metal bar optical antennas are investigated by using finite-difference time-domain (FDTD) numerical simulations and a dipole oscillator model. It is found that as the waist of the diabolo metal bar optical antenna is reduced, optical energy absorption cross section and near field enhancement at resonance increase significantly. Also reduction of the diabolo waist width causes red-shift of the resonant wavelengths in the spectra of absorption cross-section, scattering cross-section, and the near electric field. A dipole oscillator model including the self-inductance force is used to fit the FDTD numerical simulation results. The dipole oscillator model characterizes well the resonance behaviors of narrow waist diabolo metal bar optical antennas.

  20. Milk prevents the degradation of daikon (Raphanus sativus L.) isothiocyanate and enhances its absorption in rats.

    PubMed

    Ippoushi, Katsunari; Ueda, Hiroshi; Takeuchi, Atsuko

    2014-10-15

    Epidemiological and experimental researches show that isothiocyanate (ITC), a class of phytochemical compounds that imparts a characteristic biting taste and pungent odour to cruciferous vegetables, such as daikon (Japanese white radish, Raphanus sativus L. Daikon Group), broccoli, cabbage, and Chinese cabbage, possesses anticancer and anti-inflammatory properties. The concentration of daikon ITC, which degrades in aqueous solution, was measured in mixtures of daikon juice and water, corn oil, or milk. Daikon juice mixed with corn oil or milk showed a higher concentration (1.4-fold) of daikon ITC than that in mixture with water; thus, corn oil and milk prevent the degradation of daikon ITC. Moreover, orally administered daikon juice with milk increased daikon ITC absorption in rats. Therefore, dishes or drinks that include raw daikon with corn oil or milk may promote the possible health benefits of daikon ITC by preventing ITC degradation and enhancing its absorption in vivo.

  1. Near-infrared broad-band cavity enhanced absorption spectroscopy using a superluminescent light emitting diode.

    PubMed

    Denzer, W; Hamilton, M L; Hancock, G; Islam, M; Langley, C E; Peverall, R; Ritchie, G A D

    2009-11-01

    A fibre coupled near-infrared superluminescent light emitting diode that emits approximately 10 mW of radiation between 1.62 and 1.7 microm is employed in combination with a broad-band cavity enhanced spectrometer consisting of a linear optical cavity with mirrors of reflectivity approximately 99.98% and either a dispersive near-infrared spectrometer or a Fourier transform interferometer. Results are presented on the absorption of 1,3-butadiene, and sensitivities are achieved of 6.1 x 10(-8) cm(-1) using the dispersive spectrometer in combination with phase-sensitive detection, and 1.5 x 10(-8) cm(-1) using the Fourier transform interferometer (expressed as a minimum detectable absorption coefficient) over several minutes of acquisition time.

  2. Absorption enhancement of molecules in the weak plasmon-exciton coupling regime.

    PubMed

    Balci, Sinan; Karademir, Ertugrul; Kocabas, Coskun; Aydinli, Atilla

    2014-09-01

    We report on the experimental and theoretical investigations of enhancing the optical absorption of organic molecules in the weak plasmon-exciton coupling regime. A metal-organic hybrid structure consisting of dye molecules embedded in the polymer matrix is placed in close vicinity to thin metal films. We have observed a transition from a weak coupling regime to a strong coupling one as the thickness of the metal layer increases. The results indicate that absorption of the self-assembled J-aggregate nanostructures can be increased in the weak plasmon-exciton coupling regime and strongly quenched in the strong coupling regime. A theoretical model based on the transfer-matrix method qualitatively confirms the experimental results obtained from polarization-dependent spectroscopic reflection measurements.

  3. Impact of Absorption and Transport on Intelligent Therapeutics and Nano-scale Delivery of Protein Therapeutic Agents

    PubMed Central

    Peppas, Nicholas A.; Carr, Daniel A

    2009-01-01

    The combination of materials design and advances in nanotechnology has led to the development of new therapeutic protein delivery systems. The pulmonary, nasal, buccal and other routes have been investigated as delivery options for protein therapy, but none result in improved patient compliances and patient quality of life as the oral route. For the oral administration of these new systems, an understanding of protein transport is essential because of the dynamic nature of the gastrointestinal tract and the barriers to transport that exist. Models have been developed to describe the transport between the gastrointestinal lumen and the bloodstream, and laboratory techniques like cell culture provide a means to investigate the absorption and transport of many therapeutic agents. Biomaterials, including stimuli-sensitive complexation hydrogels, have been investigated as promising carriers for oral delivery. However, the need to develop models that accurately predict protein blood concentration as a function of the material structure and properties still exists. PMID:20161384

  4. Multipitched Diffraction Gratings for Surface Plasmon Resonance-Enhanced Infrared Reflection Absorption Spectroscopy.

    PubMed

    Petefish, Joseph W; Hillier, Andrew C

    2015-11-03

    We demonstrate the application of metal-coated diffraction gratings possessing multiple simultaneous pitch values for surface enhanced infrared absorption (SEIRA) spectroscopy. SEIRA increases the magnitude of vibrational signals in infrared measurements by one of several mechanisms, most frequently involving the enhanced electric field associated with surface plasmon resonance (SPR). While the majority of SEIRA applications to date have employed nanoparticle-based plasmonic systems, recent advances have shown how various metals and structures lead to similar signal enhancement. Recently, diffraction grating couplers have been demonstrated as a highly tunable platform for SEIRA. Indeed, gratings are an experimentally advantageous platform due to the inherently tunable nature of surface plasmon excitation at these surfaces since both the grating pitch and incident angle can be used to modify the spectral location of the plasmon resonance. In this work, we use laser interference lithography (LIL) to fabricate gratings possessing multiple pitch values by subjecting photoresist-coated glass slides to repetitive exposures at varying orientations. After metal coating, these gratings produced multiple, simultaneous plasmon peaks associated with the multipitched surface, as identified by infrared reflectance measurements. These plasmon peaks could then be coupled to vibrational modes in thin films to provide localized enhancement of infrared signals. We demonstrate the flexibility and tunability of this platform for signal enhancement. It is anticipated that, with further refinement, this approach might be used as a general platform for broadband enhancement of infrared spectroscopy.

  5. Plasmon-enhanced absorption in a metal nanoparticles and photosynthetic molecules hybrid system

    NASA Astrophysics Data System (ADS)

    Fan, Zhiyuan; Govorov, Alexander

    2010-03-01

    Photosystem I from cyanobacteria is one of nature's most efficient light harvesting complexes, converting light energy into electronic energy with a quantum yield of 100% and an energy yield about 58%. It is very attractive to the nanotechnology community because of its nanoscale dimensions and excellent optoelectronic properties. This protein has the potential to be utilized in devices such as solar cells, electric switches, photo-detectors, etc. However, there is one limiting factor for potential applications of a single monolayer of these photosynthetic proteins. One monolayer absorbs less than 1% of sunlight's energy, despite their excellent optoelectronic properties. Recently, experiments [1] have been conducted to enhance light absorption with the assistance of metal nanoparticles as artificial antenna for the photosystem I. Here, we present a theoretical description of the strong plasmon-assisted interactions between the metal nanoparticles and the optical dipoles of the reaction centers observed in the experiments. The resonance and off-resonance plasmon effects enhance the electromagnetic fields around the photosystem-I molecules and, in this way, lead to enhanced absorption. [4pt] [1] I. Carmeli, I. Lieberman, L. Kraversky, Zhiyuan Fan, A. O. Govorov, G. Markovich, and S. Richter, submitted.

  6. Design principle for absorption enhancement with nanoparticles in thin-film silicon solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Yuanpei; Xuan, Yimin

    2015-07-01

    The use of nanoparticles in solar cells has created many controversies. In this paper, different mechanisms of nanoparticles with different materials with diameters varying from 50 to 200 nm, surface coverage at 5, 20, and 60 %, and different locations are analyzed systematically for efficient light trapping in a thin-film c-Si solar cell. Mie theory and the finite difference time domain method are used for analysis to give a design principle with nanoparticles for the solar cell application. Metals exhibit plasmonic resonances and angular scattering, while dielectrics show anti-reflection and scattering in the incident direction. A table is given to summarize the advantages and disadvantages in different conditions. The silicon absorption enhancement with nanoparticles on top is mainly in the shorter wavelengths below 700 nm, and both Al and SiO2 nanoparticles with diameter around 100 nm show the most significant enhancement. The silicon absorption enhancement with embedded nanoparticles takes place in the longer wavelengths over 700 nm, and Ag and SiO2 nanoparticles with larger diameter around 200 nm perform better. However, the light absorbed by Ag nanoparticles will be converted to heat and will lead to decrease in cell efficiency; hence, the choice of metallic nanoparticles in applications to solar cells should be carefully considered. The design principle proposed in this work gives a guideline by choosing reasonable parameters for the different requirements in the application of thin-film solar cells.

  7. Metamaterial-enhanced vibrational absorption spectroscopy for the detection of protein molecules.

    PubMed

    Bui, Tung S; Dao, Thang D; Dang, Luu H; Vu, Lam D; Ohi, Akihiko; Nabatame, Toshihide; Lee, YoungPak; Nagao, Tadaaki; Hoang, Chung V

    2016-08-24

    From visible to mid-infrared frequencies, molecular sensing has been a major successful application of plasmonics because of the enormous enhancement of the surface electromagnetic nearfield associated with the induced collective motion of surface free carriers excited by the probe light. However, in the lower-energy terahertz (THz) region, sensing by detecting molecular vibrations is still challenging because of low sensitivity, complicated spectral features, and relatively little accumulated knowledge of molecules. Here, we report the use of a micron-scale thin-slab metamaterial (MM) architecture, which functions as an amplifier for enhancing the absorption signal of the THz vibration of an ultrathin adsorbed layer of large organic molecules. We examined bovine serum albumin (BSA) as a prototype large protein molecule and Rhodamine 6G (Rh6G) and 3,3'-diethylthiatricarbocyanine iodide (DTTCI) as examples of small molecules. Among them, our MM significantly magnified only the signal strength of bulky BSA. On the other hand, DTTCI and Rh6G are inactive, as they lack low-frequency vibrational modes in this frequency region. The results obtained here clearly demonstrate the promise of MM-enhanced absorption spectroscopy in the THz region for detection and structural monitoring of large biomolecules such as proteins or pathogenic enzymes.

  8. Metamaterial-enhanced vibrational absorption spectroscopy for the detection of protein molecules

    PubMed Central

    Bui, Tung S.; Dao, Thang D.; Dang, Luu H.; Vu, Lam D.; Ohi, Akihiko; Nabatame, Toshihide; Lee, YoungPak; Nagao, Tadaaki; Hoang, Chung V.

    2016-01-01

    From visible to mid-infrared frequencies, molecular sensing has been a major successful application of plasmonics because of the enormous enhancement of the surface electromagnetic nearfield associated with the induced collective motion of surface free carriers excited by the probe light. However, in the lower-energy terahertz (THz) region, sensing by detecting molecular vibrations is still challenging because of low sensitivity, complicated spectral features, and relatively little accumulated knowledge of molecules. Here, we report the use of a micron-scale thin-slab metamaterial (MM) architecture, which functions as an amplifier for enhancing the absorption signal of the THz vibration of an ultrathin adsorbed layer of large organic molecules. We examined bovine serum albumin (BSA) as a prototype large protein molecule and Rhodamine 6G (Rh6G) and 3,3′-diethylthiatricarbocyanine iodide (DTTCI) as examples of small molecules. Among them, our MM significantly magnified only the signal strength of bulky BSA. On the other hand, DTTCI and Rh6G are inactive, as they lack low-frequency vibrational modes in this frequency region. The results obtained here clearly demonstrate the promise of MM-enhanced absorption spectroscopy in the THz region for detection and structural monitoring of large biomolecules such as proteins or pathogenic enzymes. PMID:27555217

  9. Metamaterial-enhanced vibrational absorption spectroscopy for the detection of protein molecules

    NASA Astrophysics Data System (ADS)

    Bui, Tung S.; Dao, Thang D.; Dang, Luu H.; Vu, Lam D.; Ohi, Akihiko; Nabatame, Toshihide; Lee, Youngpak; Nagao, Tadaaki; Hoang, Chung V.

    2016-08-01

    From visible to mid-infrared frequencies, molecular sensing has been a major successful application of plasmonics because of the enormous enhancement of the surface electromagnetic nearfield associated with the induced collective motion of surface free carriers excited by the probe light. However, in the lower-energy terahertz (THz) region, sensing by detecting molecular vibrations is still challenging because of low sensitivity, complicated spectral features, and relatively little accumulated knowledge of molecules. Here, we report the use of a micron-scale thin-slab metamaterial (MM) architecture, which functions as an amplifier for enhancing the absorption signal of the THz vibration of an ultrathin adsorbed layer of large organic molecules. We examined bovine serum albumin (BSA) as a prototype large protein molecule and Rhodamine 6G (Rh6G) and 3,3‧-diethylthiatricarbocyanine iodide (DTTCI) as examples of small molecules. Among them, our MM significantly magnified only the signal strength of bulky BSA. On the other hand, DTTCI and Rh6G are inactive, as they lack low-frequency vibrational modes in this frequency region. The results obtained here clearly demonstrate the promise of MM-enhanced absorption spectroscopy in the THz region for detection and structural monitoring of large biomolecules such as proteins or pathogenic enzymes.

  10. Enabling the Intestinal Absorption of Highly Polar Anti-Viral Agents: Ion-Pair Facilitated Membrane Permeation of Zanamivir Heptyl Ester and Guanidino Oseltamivir

    PubMed Central

    Miller, Jonathan M.; Dahan, Arik; Gupta, Deepak; Varghese, Sheeba; Amidon, Gordon L.

    2012-01-01

    Anti-viral drugs often suffer from poor intestinal permeability, preventing their delivery via the oral route. The goal of this work was to enhance the intestinal absorption of the low-permeability anti-viral agents zanamivr heptyl ester (ZHE) and guanidino oseltamivir (GO) utilizing an ion-pairing approach, as a critical step toward making them oral drugs. The counterion 1-hydroxy-2-napthoic acid (HNAP) was utilized to enhance the lipophilicity and permeability of the highly polar drugs. HNAP substantially increased the log P of the drugs by up to 3.7 log units. Binding constants (K11aq) of 388 M−1 for ZHE-HNAP and 2.91 M−1 for GO.-HNAP were obtained by applying a quasi-equilibrium transport model to double-reciprocal plots of apparent octanol-buffer distribution coefficients versus HNAP concentration. HNAP enhanced the apparent permeability (Papp) of both compounds across Caco-2 cell monolayers in a concentration-dependent manner, as substantial Papp (0.8 – 3.0 × 10−6 cm/s) was observed in the presence of 6–24 mM HNAP, whereas no detectable transport was observed without counterion. Consistent with a quasi-equilibrium transport model, a linear relationship with slope near 1 was obtained from a log-log plot of Caco-2 Papp versus HNAP concentration, supporting the ion-pair mechanism behind the permeability enhancement. In the rat jejunal perfusion assay, the addition of HNAP failed to increase the effective permeability (Peff) of GO. However, the rat jejunal permeability of ZHE was significantly enhanced by the addition of HNAP in a concentration-dependent manner, from essentially zero without HNAP to 4.0 × 10−5 cm/s with 10 mM HNAP, matching the Peff of the high-permeability standard metoprolol. The success of ZHE-HNAP was explained by its >100-fold stronger K11aq versus GO-HNAP, making ZHE-HNAP less prone to dissociation and ion-exchange with competing endogenous anions and able to remain intact during membrane permeation. Overall, this work

  11. Engineered absorption enhancement and induced transparency in coupled molecular and plasmonic resonator systems.

    PubMed

    Adato, Ronen; Artar, Alp; Erramilli, Shyamsunder; Altug, Hatice

    2013-06-12

    Coupled plasmonic resonators have become the subject of significant research interest in recent years as they provide a route to dramatically enhanced light-matter interactions. Often, the design of these coupled mode systems draws intuition and inspiration from analogies to atomic and molecular physics systems. In particular, they have been shown to mimic quantum interference effects, such as electromagnetically induced transparency (EIT) and Fano resonances. This analogy also been used to describe the surface-enhanced absorption effect where a plasmonic resonance is coupled to a weak molecular resonance. These important phenomena are typically described using simple driven harmonic (or linear) oscillators (i.e., mass-on-a-spring) coupled to each other. In this work, we demonstrate the importance of an essential interdependence between the rate at which the system can be driven by an external field and its damping rate through radiative loss. This link is required in systems exhibiting time-reversal symmetry and energy conservation. Not only does it ensure an accurate and physically consistent description of resonant systems but leads directly to interesting new effects. Significantly, we demonstrate this dependence to predict a transition between EIT and electromagnetically induced absorption that is solely a function of the ratio of the radiative to intrinsic loss rates in coupled resonator systems. Leveraging the temporal coupled mode theory, we introduce a unique and intuitive picture that accurately describes these effects in coupled plasmonic/molecular and fully plasmonic systems. We demonstrate our approach's key features and advantages analytically as well as experimentally through surface-enhanced absorption spectroscopy and plasmonic metamaterial applications.

  12. Enhanced UV Absorption in Carbonaceous Aerosols during MILAGRO and Identification of Potential Organic Contributors.

    NASA Astrophysics Data System (ADS)

    Mangu, A.; Kelley, K. L.; Marchany-Rivera, A.; Kilaparty, S.; Gunawan, G.; Gaffney, J. S.; Marley, N. A.

    2007-12-01

    Measurements of aerosol absorption were obtained as part of the MAX-Mex component of the MILAGRO field campaign at site T0 (Instituto Mexicano de Petroleo in Mexico City) during the month of March, 2006 by using a 7- channel aethalometer (Thermo-Anderson). These measurements, obtained at 370, 470, 520, 590, 660, 880, and 950 nm at a 5 minute time resolution, showed an enhanced absorption in the UV over that expected from carbon soot alone. Samples of fine atmospheric aerosols (less than 0.1micron) were also collected at site T0 and T1 (Universidad Technologica de Tecamac, State of Mexico) from 5 am to 5 pm (day) and from 5 pm to 5 am (night) during the month of March 2006. The samples were collected on quartz fiber filters with high volume impactor samplers. The samples have been characterized for total carbon content (stable isotope ratio mass spectroscopy) and natural radionuclide tracers (210Pb, 210Po, 210Bi, 7Be, 13C, 14C, 40K, 15N). Continuous absorption spectra of these aerosol samples have been obtained in the laboratory from 280 to 900nm with the use of an integrating sphere coupled to a UV-visible spectrometer (Beckman DU with a Labsphere accessory). The integrating sphere allows the detector to collect and spatially integrate the total radiant flux reflected from the sample and therefore allows for the measurement of absorption on highly reflective or diffusely scattering samples (1). The continuous spectra also show an enhanced UV absorption over that expected from carbon soot and the general profiles are quite similar to those observed for humic and fulvic acids found as colloidal materials in surface and groundwaters (2), indicating the presence of humic-like substances (HULIS) in the fine aerosols. The spectra also show evidence of narrow band absorbers below 400 nm typical of polycyclic aromatics (PAH) and nitrated aromatic compounds. Spectra were also obtained on NIST standard diesel soot (SRM 2975), NIST standard air particulate matter (SRM 8785

  13. Beyond the hybridization effects in plasmonic nanoclusters: diffraction-induced enhanced absorption and scattering.

    PubMed

    Rahmani, Mohsen; Miroshnichenko, Andrey E; Lei, Dang Yuan; Luk'yanchuk, Boris; Tribelsky, Michael I; Kuznetsov, Arseniy I; Kivshar, Yuri S; Francescato, Yan; Giannini, Vincenzo; Hong, Minghui; Maier, Stefan A

    2014-02-12

    It is demonstrated herein both theoretically and experimentally that Young's interference can be observed in plasmonic structures when two or three nanoparticles with separation on the order of the wavelength are illuminated simultaneously by a plane wave. This effect leads to the formation of intermediate-field hybridized modes with a character distinct of those mediated by near-field and/or far-field radiative effects. The physical mechanism for the enhancement of absorption and scattering of light due to plasmonic Young's interference is revealed, which we explain through a redistribution of the Poynting vector field and the formation of near-field subwavelength optical vortices.

  14. Enhanced absorption with quantum dots, metal nanoparticles, and 2D materials

    NASA Astrophysics Data System (ADS)

    Simsek, Ergun; Mukherjee, Bablu; Guchhait, Asim; Chan, Yin Thai

    2016-03-01

    We fabricate and characterize mono- and few- layers of MoS2 and WSe2 on glass and SiO2/Si substrates. PbS quantum dots and/or Au nanoparticles are deposited on the fabricated thin metal dichalcogenide films by controlled drop casting and electron beam evaporation techniques. The reflection spectra of the fabricated structures are measured with a spatially resolved reflectometry setup. Both experimental and numerical results show that surface functionalization with metal nanoparticles can enhance atomically thin transition metal dichalcogenides' absorption and scattering capabilities, however semiconducting quantum dots do not create such effect.

  15. [The enhancing effect of Angelica dahurica extracts on absorption of baicalin--the active composition of Scutellaria].

    PubMed

    Zhu, Jing-yun; Liang, Xin-li; Wang, Guang-fa; Zhao, Guo-wei; Liao, Zheng-gen; Cao, Yun-chao; Chen, Xu-long; Yang, Ming

    2011-02-01

    To explore the mechanism of the absorption enhancement of Angelica dahurica extract (Ade), the absorption mechanism of baicalin in the Scutcllaria water extraction as well as the effect of Angelica dahurica extract on absorption of baicalin were investigated. In order to determine the main absorption site, everted intestinal sac model was used to study the effect of Angelica dahurica extract on the absorption of baicalin at duodenum, jejunum, ileum and colon. In situ single pass intestinal perfusion model was performed to study the absorption of various concentrations of baicalin and the effect of Angelica dahurica extract on the absorption of baicalin at the main absorption site. To authenticate the consequence of perfusion by getting the blood from the hepatic portal vein and determine the concentration of the baicalin in the blood. The result showed that baicalin could be absorbed at all of the four intestinal segments with increasing absorption amount per unit as follows: ileum > colon > jejunum > duodenum. The absorption ofbaicalin in the duodenum significantly increased with Angelica dahurica extract, thus, duodenum was chosen to be the studying site. Apparent permeability values (Papp) and absorption rate constant (Ka) of baicalin in the duodenum increased gradually with higher concentrations. When the concentration of baicalin rises to a certain degree, the absorption increase had a saturable process, the absorption of baicalin may be an active transportation. Baicalin may be not a substrate of P-gp as verapamil which had not significantly affected the Papp and Ka of baicalin. The absorption of baicalin in the duodenum significantly increased (P < 0.01) in the two models with Angelica dahurica extract and the concentration of baicalin in the blood from the hepatic portal vein showed that the Angelica dahurica extract can increase the absorption of baicalin.

  16. Enhancement of anion-exchange chromatography of DNA using compaction agents

    NASA Technical Reports Server (NTRS)

    Murphy, Jason C.; Fox, George E.; Willson, Richard C.

    2003-01-01

    The use of adsorptive chromatography for preparative nucleic acid separations is often limited by low capacity. The possibility that the adsorbent surface area sterically accessible to nucleic acid molecules could be increased by reducing their radius of gyration with compaction agents has been investigated. The equilibrium adsorption capacity of Q Sepharose anion-exchange matrix for plasmid DNA at 600 mM NaCl was enhanced by up to ca. 40% in the presence of 2.5 mM spermine. In addition, compaction agent selectivity has been demonstrated. Spermine, for example, enhances the adsorption of both plasmid and genomic DNA, spermidine enhances binding only of plasmid, and hexamine cobalt enhances only the binding of genomic DNA. Compaction may be generally useful for enhancing adsorptive separations of nucleic acids.

  17. Surface-enhanced Raman as a water monitor for warfare agents

    NASA Astrophysics Data System (ADS)

    Spencer, Kevin M.; Sylvia, James M.; Clauson, Susan L.; Janni, James A.

    2002-02-01

    The threat of chemical warfare agents being released upon civilian and military personnel continues to escalate. One aspect of chemical preparedness is to analyze and protect the portable water supply for the military. Chemical nerve, blister, and choking agents, as well as biological threats must all be analyzed and low limits of detection must be verified. For chemical agents, this generally means detection down to the low ppb levels. Surface-Enhanced Raman Spectroscopy (SERS) is a spectroscopic technique that can detect trace levels of contaminants directly in the aqueous environment. In this paper, results are presented on the use of SERS to detect chemical and biological agent simulants with an end goal of creating a Joint Service Agent Water Monitor. Detection of cyanide, 2-chloroethyl ethyl sulfide, phosphonates, Gram-positive and Gram-negative bacteria using SERS has been performed and is discussed herein. Aspects of transferring laboratory results to an unattended field instrument are also discussed.

  18. Photoluminescence intensity enhancement in SWNT aqueous suspensions due to reducing agent doping: Influence of adsorbed biopolymer

    NASA Astrophysics Data System (ADS)

    Kurnosov, N. V.; Leontiev, V. S.; Linnik, A. S.; Lytvyn, O. S.; Karachevtsev, V. A.

    2014-06-01

    The influence of biopolymer wrapped around nanotube on the enhancement of the semiconducting single-walled carbon nanotube (SWNT) photoluminescence (PL) in aqueous suspension which increases due to the reducing agent dithiothreitol (DTT) doping effect was revealed. The greatest enhancement of PL was observed for SWNTs covered with double- or single stranded DNA (above 170%) and DTT weak influence was revealed for SWNTs:polyC suspension (∼45%). The magnitude of the PL enhancement depends also on nanotube chirality and sample aging. The behavior of PL from SWNTs covered with various polymers is explained by the different biopolymers ordering on the nanotube surface. The ordered polymer conformation on the nanotube weakens the reducing agent doping effect. The method of reducing agent doping of nanotube:biopolymer aqueous suspension can serve as a sensitive luminescent probe of the biopolymer ordering on the carbon nanotube and can be used to increase the sensitivity of luminescent biosensors.

  19. Crossword Puzzles as a Tool to Enhance Learning About Anti-Ulcer Agents

    PubMed Central

    Lynch, Launa M. J.; Macias-Moriarity, Lilia Z.

    2010-01-01

    Objective To design, implement, and evaluate the use of crossword puzzles as a low-stakes educational tool for enhancing learning about anti-ulcer agents. Design Crossword puzzles were created using a free Internet resource and administered to students during 3 consecutive lectures covering the pharmacology and medicinal chemistry of anti-ulcer agents. Student perceptions of the crossword puzzle were examined using an 8-item survey instrument. Assessment Over 90% of students indicated that crossword puzzles enhanced their learning, oriented them to the important topics, and served as good reviews of the lecture material. Conclusion Students perceived that crossword puzzles enhanced their learning of anti-ulcer agents. Use of crossword puzzles provides a simple and creative way to incorporate active learning into pharmacy classroom instruction. PMID:21088722

  20. Absorption enhancement in silicon nanowire-optical nanoantenna system for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Robak, Elżbieta; Grześkiewicz, Bartłomiej; Kotkowiak, Michał

    2014-11-01

    The rapidly growing green energy sector has prompted the search for new solutions to increase the performance of solar cells. In this area there is still room for the silicon-based photovoltaic, although the main problem is to find a way to increase the efficiency of the silicon solar cells, at the lowest possible cost. In this work we investigate the influence of a gold bowtie nanoantenna on the absorption profile of silicon nanowire. Because of the energy band gap and low effective absorption cross section, bulk silicon absorbs rather poorly in longer wavelengths of visible light and near-infrared range. Our calculations with frequency domain solver show the absorption boost in nanowire at long-wavelengths due to the coupling of the large local near-field of metallic bowtie nanoantenna to the semiconductor layer. The enhancement was observed at various levels although it was correlated with the shift of localized surface plasmon resonance thus making it dependent on the bowtie geometry. The results suggest that by incorporating metallic nanostructures as well as nanoparticles to the nanowire system, the performance of photovoltaic device can be improved thanks to greater generation of a electron-hole pairs.

  1. Enhancing the absorption capabilities of thin-film solar cells using sandwiched light trapping structures.

    PubMed

    Abdellatif, S; Kirah, K; Ghannam, R; Khalil, A S G; Anis, W

    2015-06-10

    A novel structure for thin-film solar cells is simulated with the purpose of maximizing the absorption of light in the active layer and of reducing the parasitic absorption in other layers. In the proposed structure, the active layer is formed from an amorphous silicon thin film sandwiched between silicon nanowires from above and photonic crystal structures from below. The upper electrical contact consists of an indium tin oxide layer, which serves also as an antireflection coating. A metal backreflector works additionally as the other contact. The simulation was done using a new reliable, efficient and generic optoelectronic approach. The suggested multiscale simulation model integrates the finite-difference time-domain algorithm used in solving Maxwell's equation in three dimensions with a commercial simulation platform based on the finite element method for carrier transport modeling. The absorption profile, the external quantum efficient, and the power conversion efficiency of the suggested solar cell are calculated. A noticeable enhancement is found in all the characteristics of the novel structure with an estimated 32% increase in the total conversion efficiency over a cell without any light trapping mechanisms.

  2. Reduced Graphene Oxide Functionalized with Cobalt Ferrite Nanocomposites for Enhanced Efficient and Lightweight Electromagnetic Wave Absorption

    PubMed Central

    Ding, Yi; Liao, Qingliang; Liu, Shuo; Guo, Huijing; Sun, Yihui; Zhang, Guangjie; Zhang, Yue

    2016-01-01

    In this paper, reduced graphene oxide functionalized with cobalt ferrite nanocomposites (CoFe@rGO) as a novel type of electromagnetic wave (EW) absorbing materials was successfully prepared by a three-step chemical method including hydrothermal synthesis, annealing process and mixing with paraffin. The effect of the sample thickness and the amount of paraffin on the EW absorption properties of the composites was studied, revealing that the absorption peaks shifted toward the low frequency regions with the increasing thickness while other conditions had little or no effect. It is found that the CoFe@rGO enhanced both dielectric losses and magnetic losses and had the best EW absorption properties and the wide wavelength coverage of the hole Ku-Band when adding only 5wt% composites to paraffin. Therefore, CoFe@rGO could be used as an efficient and lightweight EW absorber. Compared with the research into traditional absorbing materials, this figures of merit are typically of the same order of magnitude, but given the lightweight nature of the material and the high level of compatibility with mass production standards, making use of CoFe@rGO as an electromagnetic absorber material shows great potential for real product applications. PMID:27587001

  3. Improvement of filling bismuth for x-ray absorption gratings through the enhancement of wettability

    NASA Astrophysics Data System (ADS)

    Lei, Yaohu; Liu, Xin; Li, Ji; Guo, Jinchuan; Niu, Hanben

    2016-06-01

    Filling materials with high x-ray linear absorption coefficients in high aspect-ratio (HAR) structures is a key process for the fabrication of absorption gratings used in x-ray differential phase-contrast imaging. Bismuth has been chosen as an effective filling material in micro-casting technology, because of its low cost both in price and facility use. However, repellence on structure surfaces against molten bismuth leads to an obstacle in terms of completely filling bismuth into the small-aperture and HAR microstructure formed by photo-assisted electrochemical etching in 5 inch silicon wafers. We propose and implement a novel method of surface modification to completely fill bismuth into these structures with periods of 3 μm and 42 μm, respectively, and as deep as 150 μm. The modified surface with a Bi2O3 layer covering the structure surface, including the side walls, induces an enhanced bismuth filling ratio. The superiority of the method is demonstrated by micrographs which show filled microstructures compared to the previously used method, where only a layer of 100 nm SiO2 was covered. Furthermore, we have observed that the improved micro-casting makes the absorption gratings clean surfaces, and no post treatment is needed.

  4. Oral IGF-I enhances nutrient and electrolyte absorption in neonatal piglet intestine.

    PubMed

    Alexander, A N; Carey, H V

    1999-09-01

    The effect of orally administered insulin-like growth factor-I (IGF-I) on small intestinal structure and function was studied in 5-day-old colostrum-deprived piglets. Human recombinant IGF-I (3.5 mg. kg(-1). day(-1)) or control vehicle was given orogastrically for 4 days. Body weights, jejunal and ileal mucosa wet and dry weights, and serum IGF-I levels were similar in the two groups. Small intestinal villus height and crypt depth and jejunal enterocyte microvillar dimensions were also similar between groups. Oral IGF-I produced higher rates of jejunal ion transport because of increased basal Na+ absorption. Short-circuit current responses to mucosal addition of D-glucose and L-alanine and net transepithelial absorption of 3-O-methylglucose were increased by IGF-I. Carrier-mediated uptake of D-glucose per milligram in everted jejunal sleeves was greater in IGF-I-treated piglets because of a significantly greater maximal rate of uptake. We conclude that rates of net Na+ and Na+-dependent nutrient absorption are enhanced in piglets treated with oral IGF-I, and this effect is independent of changes in mucosal mass or surface area.

  5. Enhanced two-photon absorption property of silver nanoparticle aggregates induced by a thioether derivative

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Wang, Xiao-lan; Wei, Meng-qing; Wang, Hui; Tian, Yu-peng; Li, Sheng-li; Xue, Zhao-ming; Yang, Jia-xiang; Kong, Lin

    2016-12-01

    A novel thioether derivative with two-photon absorption activity, 4,4'-((4-(dimethylamino)phenyl)methylene)bis (sulfanediyl)dianiline (abbreviated as L), was designed and synthesized, which was used to couple with Ag nanoparticles (Ag NPs, ∼6 nm) to construct L-Ag hybrid particles with L uniformly dispersed on the surface of Ag NPs. The newly-formed hybrid particles self-assembled through L-L interactions between L molecules in one hybrid particle and adjacent particle to from Ag NPs aggregates (100 nm in diameter). By Raman and XPS analysis, the interfacial interaction 'hot spot' was determined, which was between thioether group and primary amino group of L molecule and Ag+ ion on the surface of pure Ag NPs. The interfacial interactions between the two components brought about changeable linear optical properties and enhanced nonlinear optical properties, two-photon absorption cross section and two-photon absorption coefficient included. Furthermore, the optical power limiting application of Ag NPs aggregates was also optimized by this means.

  6. Scattering-enhanced absorption and interference produce a golden wing color of the burnished brass moth, Diachrysia chrysitis

    NASA Astrophysics Data System (ADS)

    Pantelić, Dejan; Savić-Šević, Svetlana; Stojanović, Dejan V.; Ćurčić, Srećko; Krmpot, Aleksandar J.; Rabasović, Mihailo; Pavlović, Danica; Lazović, Vladimir; Milošević, Vojislav

    2017-03-01

    Here we report how interference and scattering-enhanced absorption act together to produce the golden wing patches of the burnished brass moth. The key mechanism is scattering on rough internal surfaces of the wing scales, accompanied by a large increase of absorption in the UV-blue spectral range. Unscattered light interferes and efficiently reflects from the multilayer composed of the scales and the wing membranes. The resulting spectrum is remarkably similar to the spectrum of metallic gold. Subwavelength morphology and spectral and absorptive properties of the wings are described. Theories of subwavelength surface scattering and local intensity enhancement are used to quantitatively explain the observed reflectance spectrum.

  7. The tuning of light-matter coupling and dichroism in graphene for enhanced absorption: Implications for graphene-based optical absorption devices

    NASA Astrophysics Data System (ADS)

    Rakheja, Shaloo; Sengupta, Parijat

    2016-03-01

    The inter-band optical absorption in graphene characterized by its fine-structure constant has a universal value of 2.3% independent of the material parameters. However, for several graphene-based photonic applications, enhanced optical absorption is highly desired. In this work, we quantify the tunability of optical absorption in graphene via the Fermi level, angle of incidence of the incident polarized light, and the dielectric constants of the surrounding dielectric media in which graphene is embedded. The influence of impurities adsorbed on the surface of graphene on the Lorentzian broadening of the spectral function of the density of states is analytically evaluated within the equilibrium Green’s function formalism. In all the cases, we find that absorption of light graphene embedded in dielectric medium is significantly higher than 2.3%. We also compute the differential absorption of right and left circularly-polarized light in graphene that is uniaxially and optically strained. The preferential absorption or circular dichroism is investigated for armchair and zigzag strain and the interplay of k-space and velocity anisotropy is examined. Finally, we relate circular dichroism to the Berry curvature of gapped graphene and explain the connection to parameters that define the underlying Hamiltonian.

  8. A novel permeation enhancer: N-succinyl chitosan on the intranasal absorption of isosorbide dinitrate in rats.

    PubMed

    Na, Lidong; Wang, Juan; Wang, Linlin; Mao, Shirui

    2013-01-23

    The purpose of this paper is to study the potential of N-succinyl chitosan as a novel permeation enhancer for the intranasal absorption of isosorbide dinitrate (ISDN). A series of N-succinyl chitosan (NSCS) with different degree of succinylation (DS) and molecular weight were synthesized. An in situ nasal perfusion technique in rats was utilized to investigate the effect of NSCS substitution degree, NSCS molecular weight and concentration on the intranasal absorption of ISDN. The absorption enhancing effect of NSCS was compared with that of chitosan. It was found that all the NSCS investigated improved the intranasal absorption of ISDN remarkably. Better promoting effect was observed for 0.1% NSCS 50 (63) compared with 0.5% chitosan 50. In nasal ciliotoxicity test, both NSCS and chitosan investigated showed good safety profiles. Thereafter, in vivo studies of the selected formulations were carried out in rats and the pharmacokinetic parameters were calculated and compared with that of intravenous injection. Both in situ and in vivo studies demonstrated that NSCS is more effective than chitosan in promoting intranasal absorption of ISDN. Taking both absorption enhancing and safety reason into account, we suggest NSCS is a promising intranasal absorption enhancer.

  9. Mechanism of enhanced oral absorption of hydrophilic drug incorporated in hydrophobic nanoparticles

    PubMed Central

    Lv, Liang-Zhong; Tong, Chen-Qi; Yu, Jia; Han, Min; Gao, Jian-Qing

    2013-01-01

    Hydroxysafflor yellow A (HSYA) is an effective ingredient of the Chinese herb Carthamus tinctorius L, which has high water solubility and low oral bioavailability. This research aims to develop a hydrophobic nanoparticle that can enhance the oral absorption of HSYA. Transmission electron microscopy and freeze-fracture replication transmission election microscopy showed that the HSYA nanoparticles have an irregular shape and a narrow size distribution. Zonula occludens 1 protein (ZO–1) labeling showed that the nanoparticles with different dilutions produced an opening in the tight junctions of Caco-2 cells without inducing cytotoxicity to the cells. Both enhanced uptake in Caco-2 cells monolayer and increased bioavailability in rats for HSYA nanoparticles indicated that the formulation could improve bioavailability of HSYA significantly after oral administration both in vitro and in vivo. PMID:23935363

  10. Plasmon enhanced broadband optical absorption in ultrathin silicon nanobowl array for photoactive devices applications

    SciTech Connect

    Sun, Rui-Nan; Peng, Kui-Qing Hu, Bo; Hu, Ya; Zhang, Fu-Qiang; Lee, Shuit-Tong

    2015-07-06

    Both photonic and plasmonic nanostructures are key optical components of photoactive devices for light harvesting, enabling solar cells with significant thickness reduction, and light detectors capable of detecting photons with sub-band gap energies. In this work, we study the plasmon enhanced broadband light absorption and electrical properties of silicon nanobowl (SiNB) arrays. The SiNB-metal photonic-plasmonic nanostructure-based devices exhibited superior light-harvesting ability across a wide range of wavelengths up to the infrared regime well below the band edge of Si due to effective optical coupling between the SiNB array and incident sunlight, as well as electric field intensity enhancement around metal nanoparticles due to localized surface plasmon resonance. The photonic-plasmonic nanostructure is expected to result in infrared-light detectors and high-efficiency solar cells by extending light-harvesting to infrared frequencies.

  11. Small quantum absorption refrigerator in the transient regime: Time scales, enhanced cooling, and entanglement.

    PubMed

    Brask, Jonatan Bohr; Brunner, Nicolas

    2015-12-01

    A small quantum absorption refrigerator, consisting of three qubits, is discussed in the transient regime. We discuss time scales for coherent dynamics, damping, and approach to the steady state, and we study cooling and entanglement. We observe that cooling can be enhanced in the transient regime, in the sense that lower temperatures can be achieved compared to the steady-state regime. This is a consequence of coherent dynamics but can occur even when this dynamics is strongly damped by the dissipative thermal environment, and we note that precise control over couplings or timing is not needed to achieve enhanced cooling. We also show that the amount of entanglement present in the refrigerator can be much larger in the transient regime compared to the steady state. These results are of relevance to future implementations of quantum thermal machines.

  12. Optical absorption enhancement in a hybrid system photonic crystal - thin substrate for photovoltaic applications.

    PubMed

    Buencuerpo, Jeronimo; Munioz-Camuniez, Luis E; Dotor, Maria L; Postigo, Pablo A

    2012-07-02

    A hybrid approach for light trapping using photonic crystal nanostructures (nanorods, nanopillars or nanoholes) on top of an ultra thin film as a substrate is presented. The combination of a nanopatterned layer with a thin substrate shows an enhanced optical absorption than equivalent films without patterning and can compete in performance with nanostructured systems without a substrate. The designs are tested in four relevant materials: amorphous silicon (a-Si), crystalline silicon (Si), gallium arsenide (GaAs) and indium phosphide (InP). A consistent enhancement is observed for all of the materials when using a thin hybrid system (300 nm) even compared to the non patterned thin film with an anti-reflective coating (ARC). A realistic solar cell structure composed of a hybrid system with a layer of indium tin oxide (ITO) an ARC and a back metal layer is performed, showing an 18% of improvement for the nanostructured device.

  13. Plasmon enhanced broadband optical absorption in ultrathin silicon nanobowl array for photoactive devices applications

    NASA Astrophysics Data System (ADS)

    Sun, Rui-Nan; Peng, Kui-Qing; Hu, Bo; Hu, Ya; Zhang, Fu-Qiang; Lee, Shuit-Tong

    2015-07-01

    Both photonic and plasmonic nanostructures are key optical components of photoactive devices for light harvesting, enabling solar cells with significant thickness reduction, and light detectors capable of detecting photons with sub-band gap energies. In this work, we study the plasmon enhanced broadband light absorption and electrical properties of silicon nanobowl (SiNB) arrays. The SiNB-metal photonic-plasmonic nanostructure-based devices exhibited superior light-harvesting ability across a wide range of wavelengths up to the infrared regime well below the band edge of Si due to effective optical coupling between the SiNB array and incident sunlight, as well as electric field intensity enhancement around metal nanoparticles due to localized surface plasmon resonance. The photonic-plasmonic nanostructure is expected to result in infrared-light detectors and high-efficiency solar cells by extending light-harvesting to infrared frequencies.

  14. Heterogeneous delayed enhancement of the liver after ultrasound contrast agent injection--a normal variant.

    PubMed

    Okada, Masahiro; Albrecht, Thomas; Blomley, Martin J; Heckemann, Rolf A; Cosgrove, David O; Wolf, Karl-Jürgen

    2002-08-01

    We report a characteristic heterogeneous delayed liver enhancement pattern that we have encountered in a total of 6 of approximately 1500 subjects who underwent contrast-enhanced liver ultrasonography. The heterogeneous enhancement occurred several min after contrast injection and persisted for up to 1 h. It was seen in diseased as well as healthy livers and appears to represent a "normal variant" of liver enhancement. It was observed with two different contrast agents. The cause of the described effect is unknown; it may be related to the formation of large bubbles and vascular entrapment of these bubbles in the liver.

  15. Enhancement of curcumin oral absorption and pharmacokinetics of curcuminoids and curcumin metabolites in mice

    PubMed Central

    Zhongfa, Liu; Chiu, Ming; Wang, Jiang; Chen, Wei; Yen, Winston; Fan-Havard, Patty; Yee, Lisa D.; Chan, Kenneth K.

    2012-01-01

    Purpose Curcumin has shown a variety of biological activity for various human diseases including cancer in preclinical setting. Its poor oral bioavailability poses significant pharmacological barriers to its clinical application. Here, we established a practical nano-emulsion curcumin (NEC) containing up to 20% curcumin (w/w) and conducted the pharmacokinetics of curcuminoids and curcumin metabolites in mice. Methods This high loading NEC was formulated based on the high solubility of curcumin in polyethylene glycols (PEGs) and the synergistic enhancement of curcumin absorption by PEGs and Cremophor EL. The pharmacokinetics of curcuminoids and curcumin metabolites was characterized in mice using a LC–MS/MS method, and the pharmacokinetic parameters were determined using WinNonlin computer software. Results A tenfold increase in the AUC0→24h and more than 40-fold increase in the Cmax in mice were observed after an oral dose of NEC compared with suspension curcumin in 1% methylcellulose. The plasma pharmacokinetics of its two natural congeners, demethoxycurcumin and bisdemethoxycurcumin, and three metabolites, tetrahydrocurcumin (THC), curcumin-O-glucuronide, and curcumin-O-sulfate, was characterized for the first time in mice after an oral dose of NEC. Conclusion This oral absorption enhanced NEC may provide a practical formulation to conduct the correlative study of the PK of curcuminoids and their pharmacodynamics, e.g., hypomethylation activity in vivo. PMID:21968952

  16. Enhancing ferromagnetic resonance absorption for very thin insulating magnetic films with spin plasmonics

    SciTech Connect

    Chui, S. T.

    2015-05-14

    We consider enhancing the ferromagnetic resonance (FMR) absorption of very thin insulating magnetic films by placing it on top of a dielectric. We find that the signal is enhanced by at least an order of magnitude due to a new nonreciprocal interface resonance that is a mixture of the magnetic surface plasmon mode and a wave guide mode. This resonance occurs over a wide range of thicknesses of the dielectric that is still much less than the wavelength and is made possible by the negative magnetic susceptibility of the magnetic layer. The line width of absorption is reduced by an order of magnitude less than the Gilbert damping parameter. At some frequency, the group velocity of this resonance is negative. Experimentally, very thin yttrium iron garnet (YIG) films are grown on a Gadolinium Gallium Garnet (GGG) substrate which can be considered the dielectric. Our model applies to experiments performed in the YIG/GGG system. Indeed, our picture resolves the disagreement on the magnitude of the spin diffusion lengths obtained with the FMR and the Brillouin scattering techniques. It also provides for a way to make new adaptive thin film miniaturized photonic nonreciprocal devices with low loss.

  17. Novel Bone-Targeting Agent for Enhanced Delivery of Vancomycin to Bone

    PubMed Central

    Albayati, Zaineb A. F.; Sunkara, Manjula; Schmidt-Malan, Suzannah M.; Karau, Melissa J.; Morris, Andrew J.; Steckelberg, James M.; Patel, Robin; Breen, Philip J.; Smeltzer, Mark S.; Taylor, K. Grant; Merten, Kevyn E.

    2015-01-01

    We examined the pharmacokinetic properties of vancomycin conjugated to a bone-targeting agent (BT) with high affinity for hydroxyapatite after systemic intravenous administration. The results confirm enhanced persistence of BT-vancomycin in plasma and enhanced accumulation in bone relative to vancomycin. This suggests that BT-vancomycin may be a potential carrier for the systemic targeted delivery of vancomycin in the treatment of bone infections, potentially reducing the reliance on surgical debridement to achieve the desired therapeutic outcome. PMID:26666918

  18. Enhancement of Antiviral Agents Through the Use of Controlled-Release Technology.

    DTIC Science & Technology

    DL-lactide-co-glycolide) to be used as the polymeric excipients in the microencapsulation work. In addition, we have actively pursued development and testing of poly(I.C) and Je vaccine microcapsule formulations....of this research program are a) To develop a programmed-release delivery system ( microcapsule system) designed to enhance the immunogenic potential of...release microcapsule delivery systems that will enhance the effects of the following immune modulators and antiviral agents: muramyl tripeptide (MTP

  19. Tunable Nanoantennas for Surface Enhanced Infrared Absorption Spectroscopy by Colloidal Lithography and Post-Fabrication Etching

    PubMed Central

    Chen, Kai; Duy Dao, Thang; Nagao, Tadaaki

    2017-01-01

    We fabricated large-area metallic (Al and Au) nanoantenna arrays on Si substrates using cost-effective colloidal lithography with different micrometer-sized polystyrene spheres. Variation of the sphere size leads to tunable plasmon resonances in the middle infrared (MIR) range. The enhanced near-fields allow us to detect the surface phonon polaritons in the natural SiO2 thin layers. We demonstrated further tuning capability of the resonances by employing dry etching of the Si substrates with the nanoantennas acting as the etching masks. The effective refractive index of the nanoantenna surroundings is efficiently decreased giving rise to blueshifts of the resonances. In addition, partial removal of the Si substrates elevates the nanoantennas from the high-refractive-index substrates making more enhanced near-fields accessible for molecular sensing applications as demonstrated here with surface-enhanced infrared absorption (SEIRA) spectroscopy for a thin polymer film. We also directly compared the plasmonic enhancement from the Al and Au nanoantenna arrays. PMID:28272442

  20. Tunable Nanoantennas for Surface Enhanced Infrared Absorption Spectroscopy by Colloidal Lithography and Post-Fabrication Etching

    NASA Astrophysics Data System (ADS)

    Chen, Kai; Duy Dao, Thang; Nagao, Tadaaki

    2017-03-01

    We fabricated large-area metallic (Al and Au) nanoantenna arrays on Si substrates using cost-effective colloidal lithography with different micrometer-sized polystyrene spheres. Variation of the sphere size leads to tunable plasmon resonances in the middle infrared (MIR) range. The enhanced near-fields allow us to detect the surface phonon polaritons in the natural SiO2 thin layers. We demonstrated further tuning capability of the resonances by employing dry etching of the Si substrates with the nanoantennas acting as the etching masks. The effective refractive index of the nanoantenna surroundings is efficiently decreased giving rise to blueshifts of the resonances. In addition, partial removal of the Si substrates elevates the nanoantennas from the high-refractive-index substrates making more enhanced near-fields accessible for molecular sensing applications as demonstrated here with surface-enhanced infrared absorption (SEIRA) spectroscopy for a thin polymer film. We also directly compared the plasmonic enhancement from the Al and Au nanoantenna arrays.

  1. Tunable Nanoantennas for Surface Enhanced Infrared Absorption Spectroscopy by Colloidal Lithography and Post-Fabrication Etching.

    PubMed

    Chen, Kai; Duy Dao, Thang; Nagao, Tadaaki

    2017-03-08

    We fabricated large-area metallic (Al and Au) nanoantenna arrays on Si substrates using cost-effective colloidal lithography with different micrometer-sized polystyrene spheres. Variation of the sphere size leads to tunable plasmon resonances in the middle infrared (MIR) range. The enhanced near-fields allow us to detect the surface phonon polaritons in the natural SiO2 thin layers. We demonstrated further tuning capability of the resonances by employing dry etching of the Si substrates with the nanoantennas acting as the etching masks. The effective refractive index of the nanoantenna surroundings is efficiently decreased giving rise to blueshifts of the resonances. In addition, partial removal of the Si substrates elevates the nanoantennas from the high-refractive-index substrates making more enhanced near-fields accessible for molecular sensing applications as demonstrated here with surface-enhanced infrared absorption (SEIRA) spectroscopy for a thin polymer film. We also directly compared the plasmonic enhancement from the Al and Au nanoantenna arrays.

  2. Geometrical confinement of gadolinium-based contrast agents in nanoporous particles enhances T1 contrast

    PubMed Central

    Ananta, Jeyarama S.; Godin, Biana; Sethi, Richa; Moriggi, Loick; Liu, Xuewu; Serda, Rita E.; Krishnamurthy, Ramkumar; Muthupillai, Raja; Bolskar, Robert D.; Helm, Lothar; Ferrari, Mauro; Wilson, Lon J.; Decuzzi, Paolo

    2010-01-01

    Magnetic resonance imaging contrast agents are currently designed by modifying their structural and physiochemical properties in order to improve relaxivity and to enhance image contrast. Here we show a general method for increasing relaxivity by confining contrast agents inside the nanoporous structure of silicon particles. Magnevist, gadofullerenes and gadonanotubes were loaded inside the pores of quasi-hemispherical and discoidal particles. For all combinations of nanoconstructs, a boost in longitudinal proton relaxivity r1 was observed: for Magnevist, r1~14 mM-1s-1/Gd3+ion (~8.15×10+7 mM-1s-1/construct); for gadofullerenes, r1~200 mM-1s-1/Gd3+ion (~7×10+9 mM-1s-1/construct); for gadonanotubes, r1~150 mM-1s-1/Gd3+ion (~2×10+9 mM-1s-1/construct). These relaxivity values are about 4 to 50 times larger than that of clinically-available gadolinium-based agents (~4 mM-1s-1 /Gd3+ion). The enhancement in contrast is attributed to the geometrical confinement of the agents, which influences the paramagnetic behavior of the Gd3+ions. Thus, nanoscale confinement offers a new and general strategy for enhancing the contrast of gadolinium-based contrast agents. PMID:20972435

  3. Novel Oxidatively Activated Agents Modify DNA and are Enhanced by Ercc1 Silencing

    PubMed Central

    Jones, Amy R.; Bell-Horwath, Tiffany R.; Li, Guorui; Rollmann, Stephanie M.; Merino, Edward J.

    2012-01-01

    Agents that chemically modify DNA form a backbone of many cancer treatments. A key problem for DNA modifying agents is lack of specificity. To address this issue, we designed novel molecular scaffolds, termed An-Hq and An-Hq2, which are activated by a hallmark of some cancers: elevated concentrations of reactive oxygen species. Elevated reactive oxygen species are linked to oncogenesis and is found to increase in several aggressive cancers. The agents are quinones that, upon oxidation, form highly electrophilic species. In vitro studies identified the mode of addition to DNA. The aniline portion of An-Hq serves to enhance nucleophilic addition to the ethyl phenyl ether instead of forming common Michael additions. Structural characterization showed the agents add to 2′-deoxyguanosine at the N2,N3-positions. The product formed is a bulky hydroxy-N2,3-benzetheno-2′-deoxyguanosine adduct. In addition, the oxidatively activated agents added to 2′-deoxyadenosine and 2′-deoxycytidine, but not thymidine or 2′-deoxyinosine. These findings are confirmed by primer extension analysis of a 392 base pair DNA. The full-length primer extension product was reduced by 69.0 ± 0.6% upon oxidative activation of An-Hq2 compared to controls. Little sequence dependence was observed with 76% of guanine, adenine, and cytosine residues showing an increase in extension stops between two and four fold above controls. Benzetheno-nucleobase addition to double stranded DNA was confirmed by LC/MS of a self-complementary oligonucletide. Experiments were carried out to confirm in vivo DNA damage. Because of the lesion identified in vitro, we reasoned that nucleotide excision repair should be involved in reversing the effects of these oxidatively activated agents and enhance toxicity in Drosophila melanogaster. Using an RNAi based approach, Ercc1 was silenced and survival monitored after injection of an agent. As expected, bulky cross-linking DNA modifying agents, cisplatin and

  4. Surface-enhanced Raman scattering (SERS) detection for chemical and biological agents

    NASA Astrophysics Data System (ADS)

    Yan, Fei; Stokes, David L.; Wabuyele, Musundi B.; Griffin, Guy D.; Vass, Arpad A.; Vo-Dinh, Tuan

    2004-07-01

    Surface-enhanced Raman scattering (SERS) spectra of chemical agent simulants such as dimethyl methylphonate (DMMP), pinacolyl methylphosphonate (PMP), diethyl phosphoramidate (DEPA), and 2-chloroethyl ethylsulfide (CEES), and biological agent simulants such as bacillus globigii (BG), erwinia herbicola (EH), and bacillus thuringiensis (BT) were obtained from silver oxide film-deposited substrates. Thin AgO films ranging in thickness from 50 nm to 250 nm were produced by chemical bath deposition onto glass slides. Further Raman intensity enhancements were noticed in UV irradiated surfaces due to photo-induced Ag nanocluster formation, which may provide a possible route to producing highly useful plasmonic sensors for the detection of chemical and biological agents upon visible light illumination.

  5. Anti-platelet agents augment cisplatin nanoparticle cytotoxicity by enhancing tumor vasculature permeability and drug delivery

    NASA Astrophysics Data System (ADS)

    Pandey, Ambarish; Sarangi, Sasmit; Chien, Kelly; Sengupta, Poulomi; Papa, Anne-Laure; Basu, Sudipta; Sengupta, Shiladitya

    2014-11-01

    Tumor vasculature is critically dependent on platelet mediated hemostasis and disruption of the same can augment delivery of nano-formulation based chemotherapeutic agents which depend on enhanced permeability and retention for tumor penetration. Here, we evaluated the role of Clopidogrel, a well-known inhibitor of platelet aggregation, in potentiating the tumor cytotoxicity of cisplatin nano-formulation in a murine breast cancer model. In vivo studies in murine syngeneic 4T1 breast cancer model showed a significant greater penetration of macromolecular fluorescent nanoparticles after clopidogrel pretreatment. Compared to self-assembling cisplatin nanoparticles (SACNs), combination therapy with clopidogrel and SACN was associated with a 4 fold greater delivery of cisplatin to tumor tissue and a greater reduction in tumor growth as well as higher survival rate. Clopidogrel enhances therapeutic efficiency of novel cisplatin based nano-formulations agents by increasing tumor drug delivery and can be used as a potential targeting agent for novel nano-formulation based chemotherapeutics.

  6. Preparing Medical Students as Agentic Learners through Enhancing Student Engagement in Clinical Education

    ERIC Educational Resources Information Center

    Richards, Janet; Sweet, Linda; Billett, Stephen

    2013-01-01

    Preparing medical students to be agentic learners is held to be increasingly important. This is because beyond sequencing, enhancing and varying of experiences across university and health care settings, medical students require epistemological agency to optimize their learning. The positioning of students in these settings, and their engagement…

  7. Animated Pedagogical Agents Effects on Enhancing Student Motivation and Learning in a Science Inquiry Learning Environment

    ERIC Educational Resources Information Center

    van der Meij, Hans; van der Meij, Jan; Harmsen, Ruth

    2015-01-01

    This study focuses on the design and testing of a motivational animated pedagogical agent (APA) in an inquiry learning environment on kinematics. The aim of including the APA was to enhance students' perceptions of task relevance and self-efficacy. Given the under-representation of girls in science classrooms, special attention was given to…

  8. Irradiation of microorganism such as bacteria and viruses in the presence of chemical enhancing agent

    SciTech Connect

    Not Available

    1980-04-18

    This invention relates to a method for disinfecting waste material, such as sewage, containing harmful microorganisms by means of high energy ionizing radiation. This method includes the addition of a chemical enhancing agent such as aluminum chlorde or ferric chloride which would increase the sensitivity of the microorganisms to irradiation. Consequently lower radiation doses would be needed for disinfection.

  9. Detecting hydrolysis products of blister agents in water by surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Inscore, Frank; Farquharson, Stuart

    2005-11-01

    Protecting the nation's drinking water from terrorism, requires microg/L detection of chemical agents and their hydrolysis products in less than 10 minutes. In an effort to aid military personnel and the public at large, we have been investigating the ability of surface-enhanced Raman spectroscopy (SERS) to detect microgram per liter (part-per-billion) concentrations of chemical agents in water. It is equally important to detect and distinguish the hydrolysis products of these agents to eliminate false-positive responses and evaluate the extent of an attack. Previously, we reported the SER spectra of GA, GB, VX and most of their hydrolysis products. Here we extend these studies to include the chemical agent sulfur-mustard, also known as HD, and its principle hydrolysis product thiodiglycol. We also report initial continuous measurements of thiodiglycol flowing through a SERS-active capillary.

  10. Methods to Parameterize Brown Carbon, Distinguish Brown Carbon Absorption From Enhanced Black Carbon Absorption, and Assess the Stability of Brown Carbon to Photochemical Aging

    NASA Astrophysics Data System (ADS)

    Murphy, S. M.; Pokhrel, R. P.; Beamesderfer, E.; Wagner, N. L.; Langridge, J.; Lack, D.

    2015-12-01

    We present results obtained during the Fire Lab at Missoula Experiment-4 (FLAME-4) with a combination of multi-wavelength photoacoustic and cavity ringdown spectrometers. It will be shown that the single scattering albedo and Angstrom exponent of biomass burning emissions can be better parameterized by the organic carbon to black carbon ratio than by the modified combustion efficiency. Two different methods to distinguish the contribution to aerosol absorption from brown carbon versus black carbon and enhanced black carbon absorption will be presented. One method is based on extending the absorption seen at 660 nm with an assumed Angstrom exponent while the other assumes a similar absorption enhancement (determined via thermal denuder) of black carbon at 660 and 405 nm. Potential errors and advantages of both methods will be discussed. Finally, chamber experiments that show degradation of brown carbon by photochemical oxidation will be presented along with a number of methods by which to assess the amount of brown carbon that is degraded.

  11. Evaluation of skin damage caused by percutaneous absorption enhancers using fractal analysis.

    PubMed

    Obata, Y; Sesumi, T; Takayama, K; Isowa, K; Grosh, S; Wick, S; Sitz, R; Nagai, T

    2000-04-01

    Fractal analysis of the cross-sectional morphology of rat skin was conducted to evaluate pathologic changes evoked by percutaneous absorption enhancers. Male hairless rats (WBN/Ht-ILA), 8 weeks old, weighing 160 to 180 g were used. Under anesthetization, glass cells (10-mm inner diameter) were attached to the rats' abdomens, and test solutions containing various mixtures of the percutaneous absorption enhancers, sodium lauryl sulfate, isopropanol, 2-methyl-1-butanol, and sodium myristate were applied. Six hours after application, the solutions were removed and the abdominal skin was excised. Skin cross sections were analyzed with a charge-coupled device (CCD) camera. Image data taken by the CCD camera were fed into a desktop digital computer; then the fractal dimension of each skin cross section was determined on the basis of the box-counting algorithm. A pathologic study was also performed on the skin treated with the test solution. All sections of skin were examined with an optical photo microscope. Pathologic findings were classified into five levels. The total irritation score (TIS) was defined as the summation of damage levels in all regions. Only with the administration of hydrogel containing 2-methyl-1-butanol or sodium lauryl sulfate were positive values of TIS observed. However, the TIS values were independent of the concentration of these components. The most severe skin damage was evoked by application of sodium lauryl sulfate. Noticeable skin damage was also seen with 2-methyl-1-butanol. No irritation to the skin resulted from treatment with isopropanol or sodium myristate. When test solution containing sodium lauryl sulfate was applied to the skin, a remarkable increment in fractal dimensions was noted. This may suggest that the structure of the skin was greatly compromised as a result of sodium lauryl sulfate application. Although no change in fractal dimension was observed as a result of application of the test solution containing only 25

  12. Enhancing absorption in coated semiconductor nanowire/nanorod core-shell arrays using active host matrices

    NASA Astrophysics Data System (ADS)

    Jule, Leta; Dejene, Francis; Roro, Kittessa

    2016-12-01

    In the present work, we investigated theoretically and experimentally the interaction of radiation field phenomena interacting with arrays of nanowire/nanorod core-shell embedded in active host matrices. The optical properties of composites are explored including the case when the absorption of propagating wave by dissipative component is completely compensated by amplification in active (lasing) medium. On the basis of more elaborated modeling approach and extended effective medium theory, the effective polarizability and the refractive index of electromagnetic mode dispersion of the core-shell nanowire arrays are derived. ZnS(shell)-coated by sulphidation process on ZnO(shell) nanorod arrays grown on (100) silicon substrate by chemical bath deposition (CBD) has been used for theoretical comparison. Compared with the bare ZnO nanorods, ZnS-coated core/shell nanorods exhibit a strongly reduced ultraviolet (UV) emission and a dramatically enhanced deep level (DL) emission. Obviously, the UV and DL emission peaks are attributed to the emissions of ZnO nanorods within ZnO/ZnS core/shell nanorods. The reduction of UV emission after ZnS coating seems to agree with the charge separation mechanism of type-II band alignment that holes transfer from the core to shell, which would quench the UV emission to a certain extent. Our theoretical calculations and numerical simulation demonstrate that the use of active host (amplifying) medium to compensate absorption at metallic inclusions. Moreover the core-shell nanorod/nanowire arrays create the opportunity for broad band absorption and light harvesting applications.

  13. Broadband absorption enhancement in plasmonic nanoshells-based ultrathin microcrystalline-Si solar cells

    PubMed Central

    Raja, Waseem; Bozzola, Angelo; Zilio, Pierfrancesco; Miele, Ermanno; Panaro, Simone; Wang, Hai; Toma, Andrea; Alabastri, Alessandro; De Angelis, Francesco; Zaccaria, Remo Proietti

    2016-01-01

    With the objective to conceive a plasmonic solar cell with enhanced photocurrent, we investigate the role of plasmonic nanoshells, embedded within a ultrathin microcrystalline silicon solar cell, in enhancing broadband light trapping capability of the cell and, at the same time, to reduce the parasitic loss. The thickness of the considered microcrystalline silicon (μc-Si) layer is only ~1/6 of conventional μc-Si based solar cells while the plasmonic nanoshells are formed by a combination of silica and gold, respectively core and shell. We analyze the cell optical response by varying both the geometrical and optical parameters of the overall device. In particular, the nanoshells core radius and metal thickness, the periodicity, the incident angle of the solar radiation and its wavelength are varied in the widest meaningful ranges. We further explain the reason for the absorption enhancement by calculating the electric field distribution associated to resonances of the device. We argue that both Fabry-Pérot-like and localized plasmon modes play an important role in this regard. PMID:27080420

  14. Epithelial transport of noscapine across cell monolayer and influence of absorption enhancers on in vitro permeation and bioavailability: implications for intestinal absorption.

    PubMed

    Chougule, Mahavir B; Patel, Apurva R; Patlolla, Ram; Jackson, Tanise; Singh, Mandip

    2014-07-01

    The purpose of this study was to investigate the permeation of Noscapine (Nos) across the Caco-2 and Madin-Darby canine kidney (MDCK) cell monolayers and to evaluate the influence of absorption enhancers on in vitro and in vivo absorption of Nos. The bidirectional transport of Nos was studied in Caco-2 and MDCK cell monolayers at pH 5.0-7.8. The effect of 0.5% w/v chitosan (CH) or Captisol (CP) on Nos permeability was investigated at pH 5.0 and 5.8. The effect of 1-5% w/v of CP on oral bioavailability of Nos (150 mg/kg) was evaluated in Sprague-Dawley rats. The effective permeability coefficients (Peff) of Nos across Caco-2 and MDCK cell monolayers was found to be in the order of pH 5.0 > 5.8 > 6.8 > 7.8. The efflux ratios of Peff < 2 demonstrated that active efflux does not limit the absorption of Nos. The use of CH or CP have shown significant (***, p < 0.001) enhancement in Peff of Nos across cell monolayer compared with the control group. The CP (1-5% w/v) based Nos formulations resulted in significant (***, p < 0.001) increase in the bioavailability of Nos compared with Nos solution. The use of CP represents viable approach for enhancing the oral bioavailability of Nos and reducing the required dose.

  15. Influence of the cavity parameters on the output intensity in incoherent broadband cavity-enhanced absorption spectroscopy.

    PubMed

    Fiedler, Sven E; Hese, Achim; Heitmann, Uwe

    2007-07-01

    The incoherent broadband cavity-enhanced absorption spectroscopy is a technique in measuring small absorptions over a broad wavelength range. The setup consists of a conventional absorption spectrometer using an incoherent lamp and a charge coupled device detector, as well as a linear optical cavity placed around the absorbing sample, which enhances the effective path length through the sample. In this work the consequences of cavity length, mirror curvature, reflectivity, different light injection geometries, and spot size of the light source on the output intensity are studied and the implications to the signal-to-noise ratio of the absorption measurement are discussed. The symmetric confocal resonator configuration is identified as a special case with optimum imaging characteristics but with higher requirements for mechanical stability. Larger spot sizes of the light source were found to be favorable in order to reduce the negative effects of aberrations on the intensity.

  16. Enhancement of microbial motility due to advection-dependent nutrient absorption

    NASA Astrophysics Data System (ADS)

    Condat, Carlos A.; di Salvo, Mario E.

    2014-03-01

    In their classical work, Berg and Purcell [Biophys. J. 20, 193 (1977)] concluded that the motion of a small microorganism would not significantly increase its nutrient uptake rate, if the nutrient consisted of high diffusivity particles. As a result, it has been generally assumed that nutrient transport to small microorganisms such as bacteria is dominated by molecular diffusion and that swimming and feeding currents play a negligible role. On the other hand, recent studies have found that flagellar motion may increase advection-mediated uptake. We formulate a model to investigate the hypothesis that fast-moving microbes may enhance their swimming speed by taking advantage of advection to increase nutrient absorption. Surprisingly, using realistic parameter values for bacteria and algae, we find that even modest increases in nutrient absorption may lead to a significant increase of the microbial speed. We also show that, optimally, the rate of effective energy transfer to the microbial propulsion system should be proportional to the speed for slow motion, while it should be proportional to a power of the speed close to two for fast motion. We are grateful to SECyT-UNC and CONICET, Argentina, for financial support.

  17. Enhanced dissolution and oral absorption of tacrolimus by supersaturable self-emulsifying drug delivery system

    PubMed Central

    Lee, Dae Ro; Ho, Myoung Jin; Jung, Hyuck Jun; Cho, Ha Ra; Park, Jun Seo; Yoon, Suk-Hyun; Choi, Yong Seok; Choi, Young Wook; Oh, Chung-Hun; Kang, Myung Joo

    2016-01-01

    A new Soluplus (polyvinyl caprolactam–polyvinyl acetate–polyethylene glycol graft copolymer)-based supersaturable self-emulsifying drug delivery system (S-SEDDS) was formulated to enhance oral absorption of tacrolimus (FK506) with minimal use of oil, surfactant, and cosurfactant. A high payload supersaturable system (S-SEDDS) was prepared by incorporating Soluplus, as a precipitation inhibitor, to SEDDS consisting of Capmul MCM, Cremophor EL, and Transcutol (FK506:vehicle:Soluplus =1:15:1). In vitro dissolution profile and in vitro pharmacokinetic aspect of S-SEDDS in rats were comparatively evaluated with those of conventional SEDDS formulas containing four times greater content of vehicle components (FK506:vehicle =1:60). Both formulations formed spherical drug-loaded microemulsion <70 nm in size when in contact with aqueous medium. In an in vitro dissolution test in a nonsink condition, the amphiphilic polymer noticeably retarded drug precipitation and maintained >80% of accumulated dissolution rate for 24 hours, analogous to that from conventional SEDDS. Moreover, pharmacokinetic parameters of the maximum blood concentration and area under the curve from S-SEDDS formula in rats were not statistically different (P>0.05) than those of conventional SEDDS. The results suggest that the Soluplus-based supersaturable system can be an alternative to achieve a comparable in vitro dissolution profile and in vivo oral absorption with conventional SEDDS, with minimal use of vehicle ingredients. PMID:27051286

  18. Enhancing light absorption within the carrier transport length in quantum junction solar cells.

    PubMed

    Fu, Yulan; Hara, Yukihiro; Miller, Christopher W; Lopez, Rene

    2015-09-10

    Colloidal quantum dot (CQD) solar cells have attracted tremendous attention because of their tunable absorption spectrum window and potentially low processing cost. Recently reported quantum junction solar cells represent a promising approach to building a rectifying photovoltaic device that employs CQD layers on each side of the p-n junction. However, the ultimate efficiency of CQD solar cells is still highly limited by their high trap state density in both p- and n-type CQDs. By modeling photonic structures to enhance the light absorption within the carrier transport length and by ensuring that the carrier generation and collection efficiencies were both augmented, our work shows that overall device current density could be improved. We utilized a two-dimensional numerical model to calculate the characteristics of patterned CQD solar cells based on a simple grating structure. Our calculation predicts a short circuit current density as high as 31  mA/cm2, a value nearly 1.5 times larger than that of the conventional flat design, showing the great potential value of patterned quantum junction solar cells.

  19. 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.

  20. Shock-tube measurements of excited oxygen atoms using cavity-enhanced absorption spectroscopy.

    PubMed

    Nations, Marcel; Wang, Shengkai; Goldenstein, Christopher S; Sun, Kai; Davidson, David F; Jeffries, Jay B; Hanson, Ronald K

    2015-10-10

    We report the use of cavity-enhanced absorption spectroscopy (CEAS) using two distributed feedback diode lasers near 777.2 and 844.6 nm for sensitive, time-resolved, in situ measurements of excited-state populations of atomic oxygen in a shock tube. Here, a 1% O2/Ar mixture was shock-heated to 5400-8000 K behind reflected shock waves. The combined use of a low-finesse cavity, fast wavelength scanning of the lasers, and an off-axis alignment enabled measurements with 10 μs time response and low cavity noise. The CEAS absorption gain factors of 104 and 142 for the P35←S520 (777.2 nm) and P0,1,23←S310 (844.6 nm) atomic oxygen transitions, respectively, significantly improved the detection sensitivity over conventional single-pass measurements. This work demonstrates the potential of using CEAS to improve shock-tube studies of nonequilibrium electronic-excitation processes at high temperatures.

  1. The mechanisms for enhanced oral absorption of hydroxysafflor yellow A by chuanxiong volatile oil.

    PubMed

    Qi, Jianping; Sun, Minjie; Ping, Qineng; Zhuang, Jie; Li, Jiangran; Peddie, Frank; Song, Yunmei

    2010-05-01

    The aims of this study were to investigate the effect of ligusticum chuanxiong volatile oil (CVO) on the oral absorption of hydroxysafflor yellow A (HSYA). The effects were studied both IN VITRO and IN VIVO. The contents of CVO were measured by GC-MS. The Caco-2 cell model was used to evaluate HSYA permeation with or without the presence of CVO. Transepithelial electrical resistance (TEER) of the Caco-2 cell monolayers was monitored and the alteration in the subcellular localization of claudin-1, the tight junction protein, was observed by immunofluorescence. The irritation of CVO on rat intestine was studied by paraffin slice technology. Our results demonstrated that CVO mainly contained ligustilide (47.82 %). The Papp of HSYA was improved by 5.34-fold and 4.62-fold in the presence of 0.02 mg/mL and 0.01 mg/mL of CVO, respectively. After opening of the tight junctions of the Caco-2 cell monolayer, TEER decreased, the position of claudin-1 changed, and its expression increased. CVO at different concentrations (10, 25, 100 and 200 mg/kg) caused no significant irritation on rat intestine. The bioavailability of HSYA in rats was increased by 6.48-fold and 4.91-fold when 100 and 25 mg/kg of CVO were co-administrated, respectively. CVO was an effective absorption enhancer for oral delivery of BCS III drugs. It can cause redistribution of claudin-1 proteins and open the tight junctions.

  2. Time-resolved broadband cavity-enhanced absorption spectroscopy for chemical kinetics.

    SciTech Connect

    Sheps, Leonid; Chandler, David W.

    2013-04-01

    Experimental measurements of elementary reaction rate coefficients and product branching ratios are essential to our understanding of many fundamentally important processes in Combustion Chemistry. However, such measurements are often impossible because of a lack of adequate detection techniques. Some of the largest gaps in our knowledge concern some of the most important radical species, because their short lifetimes and low steady-state concentrations make them particularly difficult to detect. To address this challenge, we propose a novel general detection method for gas-phase chemical kinetics: time-resolved broadband cavity-enhanced absorption spectroscopy (TR-BB-CEAS). This all-optical, non-intrusive, multiplexed method enables sensitive direct probing of transient reaction intermediates in a simple, inexpensive, and robust experimental package.

  3. Enhancement of energy absorption in a closed-cell aluminum by the modification of cellular structures

    SciTech Connect

    Miyoshi, T.; Itoh, M.; Mukai, T.; Kanahashi, H.; Kohzu, H.; Tanabe, S.; Higashi, K.

    1999-10-22

    Recently, there is a high interest in using light-weight metallic foams (e.g., Al and Mg) for automotive, railway and aerospace applications where weight reduction and improvement in comfort are needed. Metallic foams also have a potential for absorbing impact energy during the crashing of a vehicle either against another vehicle or a pedestrian. In this study, enhancement of absorption energy in a closed-cell structure has been performed by an increase in the aspect ratio of cell-wall thickness against the cell-edge length with the reduction of cell size. The absorbed energy in a modified foam is estimated comparing with that in a conventional ALPORAS with the same relative density.

  4. Biomimetic environment to study E. coli complex I through surface-enhanced IR absorption spectroscopy.

    PubMed

    Kriegel, Sébastien; Uchida, Taro; Osawa, Masatoshi; Friedrich, Thorsten; Hellwig, Petra

    2014-10-14

    In this study complex I was immobilized in a biomimetic environment on a gold layer deposited on an ATR-crystal in order to functionally probe the enzyme against substrates and inhibitors via surface-enhanced IR absorption spectroscopy (SEIRAS) and cyclic voltammetry (CV). To achieve this immobilization, two methods based on the generation of a high affinity self-assembled monolayer (SAM) were probed. The first made use of the affinity of Ni-NTA toward a hexahistidine tag that was genetically engineered onto complex I and the second exploited the affinity of the enzyme toward its natural substrate NADH. Experiments were also performed with complex I reconstituted in lipids. Both approaches have been found to be successful, and electrochemically induced IR difference spectra of complex I were obtained.

  5. Resonance-induced absorption enhancement in colloidal quantum dot solar cells using nanostructured electrodes.

    PubMed

    Mahpeykar, Seyed Milad; Xiong, Qiuyang; Wang, Xihua

    2014-10-20

    The application of nanostructured indium-doped tin oxide (ITO) electrodes as diffraction gratings for light absorption enhancement in colloidal quantum dot solar cells is numerically investigated using finite-difference time-domain (FDTD) simulation. Resonant coupling of the incident diffracted light with supported waveguide modes in light absorbing layer at particular wavelengths predicted by grating far-field projection analysis is shown to provide superior near-infrared light trapping for nanostructured devices as compared to the planar structure. Among various technologically feasible nanostructures, the two-dimensional nano-branch array is demonstrated as the most promising polarization-independent structure and proved to be able to maintain its performance despite structural imperfections common in fabrication.

  6. Enhanced light absorption of amorphous silicon thin film by substrate control and ion irradiation

    PubMed Central

    2014-01-01

    Large-area periodically aligned silicon nanopillar (PASiNP) arrays were fabricated by magnetic sputtering with glancing angle deposition (GLAD) on substrates coated by a monolayer of close-packed polystyrene (PS) nanospheres. The structure of PASiNP arrays could be manipulated by changing the diameter of PS nanospheres. Enhanced light absorptance within a wavelength range from 300 to 1,000 nm was observed as the diameter of nanopillars and porosity of PASiNP arrays increased. Meanwhile, Xe ion irradiation with dose from 1 × 1014 to 50 × 1014 ions/cm2 was employed to modify the surface morphology and top structure of thin films, and the effect of the irradiation on the optical bandgap was discussed. PACS code 81.15.Cd; 78.66.Jg; 61.80.Jh PMID:24717078

  7. Enhancement of absorption in vertically-oriented graphene sheets growing on a thin copper layer

    NASA Astrophysics Data System (ADS)

    Rozouvan, Tamara; Poperenko, Leonid; Kravets, Vasyl; Shaykevich, Igor

    2017-02-01

    The optical properties and surface structure of graphene films grown on thin copper Cu (1 μm) layer using chemical vapour deposition method were investigated via spectroscopic ellipsometry and nanoscopic measurements. Angle variable ellipsometry measurements were performed to analyze the features of dispersion of the complex refractive index and optical conductivity. It was observed significant enhancement of the absorption band in the vertically-oriented graphene sheets layer with respect to the bulk graphite due to interaction between excited localized surface plasmon at surface of thin Cu layer and graphene's electrons. Scanning tunneling microscopy measurements with atomic spatial resolution revealed vertical crystal lattice structure of the deposited graphene layer. The obtained results provide direct evidence of the strong influence of the growing condition and morphology of nanostructure on electronic and optical behaviours of graphene film.

  8. Multiband InGaN nanowires with enhanced visible photon absorption for efficient photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, M.; Gopalakrishnan, S.; Bhalerao, G. M.; Jeganathan, K.

    2017-01-01

    Ultralong compositional tunable InGaN nanowires as a photoanode, grown by chemical vapour deposition technique using catalyst-free approach, exhibits high efficiency solar water splitting for the first time without co-catalyst. The high density of unique ultralong InGaN nanowires with high intense multiband emission in the visible region improves the absorption of photon, thereby significantly increasing the photocurrent density of ∼32 mA/cm2 at 1.0 V against Pt counter electrode. The small diameter of InGaN nanowires favours the diffusion of the charge carriers to the surface before recombination which results in enhanced solar energy conversion efficiency. Multiband InGaN nanowires demonstrate a maximum applied bias photon-to-current efficiency of ∼16.19% at 0.34 V under AM1.5G one sun illumination.

  9. Broadband Absorption Enhancement in Thin Film Solar Cells Using Asymmetric Double-Sided Pyramid Gratings

    NASA Astrophysics Data System (ADS)

    Alshal, Mohamed A.; Allam, Nageh K.

    2016-11-01

    A design for a highly efficient modified grating crystalline silicon (c-Si) thin film solar cell is demonstrated and analyzed using the two-dimensional (2-D) finite element method. The suggested grating has a double-sided pyramidal structure. The incorporation of the modified grating in a c-Si thin film solar cell offers a promising route to harvest light into the few micrometers active layer. Furthermore, a layer of silicon nitride is used as an antireflection coating (ARC). Additionally, the light trapping through the suggested design is significantly enhanced by the asymmetry of the top and bottom pyramids. The effects of the thickness of the active layer and facet angle of the pyramid on the spectral absorption, ultimate efficiency ( η), and short-circuit current density ( J sc) are investigated. The numerical results showed 87.9% efficiency improvement over the conventional thin film c-Si solar cell counterpart without gratings.

  10. Enhancement of Phosphate Absorption by Garden Plants by Genetic Engineering: A New Tool for Phytoremediation

    PubMed Central

    Togami, Junichi; Mason, John G.; Chandler, Stephen F.; Tanaka, Yoshikazu

    2013-01-01

    Although phosphorus is an essential factor for proper plant growth in natural environments, an excess of phosphate in water sources causes serious pollution. In this paper we describe transgenic plants which hyperaccumulate inorganic phosphate (Pi) and which may be used to reduce environmental water pollution by phytoremediation. AtPHR1, a transcription factor for a key regulator of the Pi starvation response in Arabidopsis thaliana, was overexpressed in the ornamental garden plants Torenia, Petunia, and Verbena. The transgenic plants showed hyperaccumulation of Pi in leaves and accelerated Pi absorption rates from hydroponic solutions. Large-scale hydroponic experiments indicated that the enhanced ability to absorb Pi in transgenic torenia (AtPHR1) was comparable to water hyacinth a plant that though is used for phytoremediation causes overgrowth problems. PMID:23984322

  11. Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil.

    PubMed

    Unlu, Nuray Z; Bohn, Torsten; Clinton, Steven K; Schwartz, Steven J

    2005-03-01

    Dietary lipids are hypothesized to be an important factor for carotenoid bioavailability. However, most carotenoid-rich fruits and vegetables are low in lipids. The objective of this study was to assess whether the addition of avocado fruit as a lipid source enhances carotenoid absorption in humans. Healthy subjects (n = 11/study) were recruited for 2 crossover, postprandial studies. The effect of avocado addition (150 g) to salsa on lycopene and beta-carotene absorption was examined in Study 1, and the absorption of lutein, alpha-carotene, and beta-carotene from salad in Study 2. Furthermore, the effects of avocado dose (75 vs. 150 g containing 12 vs. 24 g lipid, respectively) and of lipid source (avocado fruit vs. avocado oil) on carotenoid absorption were examined in Study 2. Intact carotenoids were quantified in the plasma triacylglycerol-rich lipoprotein (TRL) fraction during the 9.5 h after consumption of the test meal and expressed as baseline-corrected area under the concentration-vs.-time curve (AUC). The addition of avocado to salsa enhanced lycopene and beta-carotene absorption (P < 0.003), resulting in 4.4 and 2.6 times the mean AUC after intake of avocado-free salsa, respectively. In Study 2, supplementing 150 g avocado or 24 g avocado oil to salad similarly enhanced alpha-carotene, beta-carotene, and lutein absorption (P < 0.01), resulting in 7.2, 15.3, and 5.1 times the mean AUC after intake of avocado-free salad, respectively (150 g avocado). Neither the avocado dose nor the lipid source affected carotenoid absorption. In conclusion, adding avocado fruit can significantly enhance carotenoid absorption from salad and salsa, which is attributed primarily to the lipids present in avocado.

  12. Luminal Glucose Does Not Enhance Active Intestinal Calcium Absorption in mice: Evidence Against a Role for Cav1.3 as a Mediator of Calcium Uptake During Absorption

    PubMed Central

    Reyes-Fernandez, Perla C.; Fleet, James C.

    2015-01-01

    Intestinal Ca absorption occurs through a 1,25 dihydroxyvitamin D3 (1,25(OH)2D3)-regulated transcellular pathway, especially when habitual dietary Ca intake is low. Recently the L-type voltage-gated Ca channel, Cav1.3, was proposed to mediate active, transcellular Ca absorption in response to membrane depolarization caused by elevated luminal glucose levels following a meal. We tested the hypothesis that high luminal glucose could reveal a role for Cav1.3 in active intestinal Ca absorption in mice. Nine week-old male C57BL/6J mice were fed AIN93G diets containing either low (0.125%) or high (1%) Ca for 1 week and Ca absorption was examined by an oral gavage method using a 45Ca-transport buffer containing 25 mmol/L of glucose or fructose. Transient receptor potential vanilloid 6 (TRPV6), Calbindin D9k (CaBPD9k) and Cav1.3 mRNA levels were measured in the duodenum, jejunum and ileum. TRPV6 and CaBPD9k expression were highest in the duodenum, where active, 1,25(OH)2D3-regulated Ca absorption occurs while Cav1.3 mRNA levels were similar across the intestinal segments. As expected, the low Ca diet increased renal cytochrome p450-27B1 (CYP27B1) mRNA (p=0.003), serum 1,25(OH)2D3 (p<0.001) and Ca absorption efficiency by 2-fold with the fructose buffer. However, the glucose buffer used to favor Cav1.3 activation did not increase Ca absorption efficiency (p=0.6) regardless of the dietary Ca intake level. Collectively, our results show that glucose did not enhance Ca absorption and they do not support a critical role for Cav1.3 in either basal or vitamin D-regulated intestinal Ca absorption in vivo. PMID:26403486

  13. Erythropoiesis-stimulating agents and other methods to enhance oxygen transport

    PubMed Central

    Elliott, S

    2008-01-01

    Oxygen is essential for life, and the body has developed an exquisite method to collect oxygen in the lungs and transport it to the tissues. Hb contained within red blood cells (RBCs), is the key oxygen-carrying component in blood, and levels of RBCs are tightly controlled according to demand for oxygen. The availability of oxygen plays a critical role in athletic performance, and agents that enhance oxygen delivery to tissues increase aerobic power. Early methods to increase oxygen delivery included training at altitude, and later, transfusion of packed RBCs. A breakthrough in understanding how RBC formation is controlled included the discovery of erythropoietin (Epo) and cloning of the EPO gene. Cloning of the EPO gene was followed by commercial development of recombinant human Epo (rHuEpo). Legitimate use of this and other agents that affect oxygen delivery is important in the treatment of anaemia (low Hb levels) in patients with chronic kidney disease or in cancer patients with chemotherapy-induced anaemia. However, competitive sports was affected by illicit use of rHuEpo to enhance performance. Testing methods for these agents resulted in a cat-and-mouse game, with testing labs attempting to detect the use of a drug or blood product to improve athletic performance (doping) and certain athletes developing methods to use the agents without being detected. This article examines the current methods to enhance aerobic performance and the methods to detect illicit use. PMID:18362898

  14. Distributed Multi-Agent-Based Protection Scheme for Transient Stability Enhancement in Power Systems

    NASA Astrophysics Data System (ADS)

    Rahman, M. S.; Mahmud, M. A.; Pota, H. R.; Hossain, M. J.; Orchi, T. F.

    2015-04-01

    This paper presents a new distributed agent-based scheme to enhance the transient stability of power systems by maintaining phase angle cohesiveness of interconnected generators through proper relay coordination with critical clearing time (CCT) information. In this distributed multi-agent infrastructure, intelligent agents represent various physical device models to provide dynamic information and energy flow among different physical processes of power systems. The agents can communicate with each other in a distributed manner with a final aim to control circuit breakers (CBs) with CCT information as this is the key issue for maintaining and enhancing the transient stability of power systems. The performance of the proposed scheme is evaluated on a standard IEEE 39-bus New England benchmark system under different large disturbances such as three-phase short-circuit faults and changes in loads within the systems. From the simulation results, it is found that the proposed scheme significantly enhances the transient stability of power systems as compared to a conventional scheme of static CB operation.

  15. Influence of Chitosan Nanoparticles as the Absorption Enhancers on Salvianolic acid B In vitro and In vivo Evaluation

    PubMed Central

    Jin, Xin; Zhang, Shi-bing; Li, Shi-meng; Liang, Ke; Jia, Zeng-yong

    2016-01-01

    Background: Salvianolic acid B (SalB) represents the most abundant and bio-active phenolic constituent among the water-soluble compounds of Salvia miltiorrhiza. But the therapeutic potential of SalB has been significantly restricted by its poor absorption. Methods: In this study, chitosans (CS) and CS nanoparticles (NPs) with different molecular weights (MWs), which have influence on the absorption of SalB, was also investigated. Results: As a preliminary study, water-soluble CS with various MWs (3, 30, 50, and 100 kDa) was chosen. We investigated the MW-dependent Caco-2 cell layer transport phenomena in vitro of CS and NPs at concentrations (4 μg/ml, w/v). SalB, in presence CS or NPs has no significant toxic effect on Caco-2 cell. As the MW increases, the absorption enhancing effect of CS increases. However, as the MW decreases, the absorption enhancing effect of NPs increases. The AUC0–∞ of the SalB-100 kDa CS was 4.25 times greater than that of free SalB. And the AUC0–∞ of the SalB-3 kDa NPs was 16.03 times greater than that of free SalB. Conclusion: CS and NPs with different MWs as the absorption enhancers can promote the absorption of SalB. And the effect on NPs is better than CS. SUMMARY Formation mechanism for NPs PMID:27019562

  16. 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

    2016-03-02

    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.

  17. NO_2 Trace Measurements by Optical-Feedback Cavity-Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ventrillard-Courtillot, I.; Desbois, Th.; Foldes, T.; Romanini, D.

    2009-06-01

    In order to reach the sub-ppb NO_2 detection level required for environmental applications in remote areas, we develop a spectrometer based on a technique introduced a few years ago, named Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OF-CEAS) [1]. It allows very sensitive and selective measurements, together with the realization of compact and robust set-ups as was subsequently demonstrated during measurements campaigns in harsh environments [2]. OF-CEAS benefits from the optical feedback to efficiently inject a cw-laser in a V-shaped high finesse cavity (typically 10 000). Cavity-enhanced absorption spectra are acquired on a small spectral region (˜1 cm^{-1}) that enables selective and quantitative measurements at a fast acquisition rate with a detection limit of several 10^{-10} cm^{-1} as reported in this work. Spectra are obtained with high spectral definition (150 MHz highly precisely spaced data points) and are self calibrated by cavity rind-down measurements regularly performed (typically every second). NO_2 measurements are performed with a commercial extended cavity diode laser around 411 nm, spectral region where intense electronic transitions occur. We will describe the set-up developed for in-situ measurements allowing real time concentration measurements at typically 5 Hz; and then report on the measurements performed with calibrated NO_2 reference samples to evaluate the linearity of the apparatus. The minimum detectable absorption loss is estimated by considering the standard deviation of the residual of one spectrum. We achieved 2x10^{-10} cm^{-1} for a single spectrum recorded in less than 100 ms at 100 mbar. It leads to a potential detection limit of 3x10^8 molecules/cm^3, corresponding to about 150 pptv at this pressure. [1] J. Morville, S. Kassi, M. Chenevier, and D. Romanini, Appl. Phys. B, 80, 1027 (2005). [2] D. Romanini, M. Chenevrier, S. Kassi, M. Schmidt, C. Valant, M. Ramonet, J. Lopez, and H.-J. Jost, Appl. Phys. B, 83, 659

  18. Polymeric coupling agents for enhancing the adhesion of epoxy to steel

    NASA Astrophysics Data System (ADS)

    Vaideeswaran, Karthik

    The work described in this dissertation involves the conceptualization, design, development and testing of new polymers for their efficiency as coupling agents to enhance the bonding of steel to epoxy. Two novel series of polymeric coupling agents have been tested viz., a quinone-amine polyurethane (QAP) series and a beta-diketone functionalized polymer (BFP) series. Several QAP and BFP polymers were synthesized and studied. These polymers were characterized using Infrared spectroscopy, thermal analyses (Thermogravimetric Analysis, Differential Scanning Calorimetry) and Gel Permeation Chromatography. The surfaces of QAP and BFP polymeric coupling agent treated steel coupons were analyzed using Infrared Reflection Spectroscopy, Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy. These tests gave indications that the QAPs and BFPs interact with the steel surface chemically. The QAPs and BFPs were found to be very effective coupling agents for the steel-epoxy system. The coupling agent treated epoxy-steel torsional joints were tested (in dry and wet environments) in shear. The QAPs were compared with commercial silanes and demonstrated a 10-15% better strength retention and hot water durability. The QAP treated and epoxy resin topcoated steel coupons demonstrated excellent corrosion resistance when tested in a lab-scale salt-spray chamber. The process conditions (in the coupling agent based polymer coating process for steel described in this dissertation) are mild and process control is relatively simple. This organic coating process is more environmentally friendly than other conventionally used toxic processes for steel like Chrome Etching.

  19. Progress in Nanotechnology Based Approaches to Enhance the Potential of Chemopreventive Agents

    PubMed Central

    Muqbil, Irfana; Masood, Ashiq; Sarkar, Fazlul H.; Mohammad, Ramzi M.; Azmi, Asfar S.

    2011-01-01

    Cancer chemoprevention is defined as the use of natural agents to suppress, reverse or prevent the carcinogenic process from turning into aggressive cancer. Over the last two decades, multiple natural dietary compounds with diverse chemical structures such flavonoids, tannins, curcumins and polyphenols have been proposed as chemopreventive agents. These agents have proven excellent anticancer potential in the laboratory setting, however, the observed effects in vitro do not translate in clinic where they fail to live up to their expectations. Among the various reasons for this discrepancy include inefficient systemic delivery and robust bioavailability. To overcome this barrier, researchers have focused towards coupling these agents with nano based encapsulation technology that in principle will enhance bioavailability and ultimately benefit clinical outcome. The last decade has witnessed rapid advancement in the development of nanochemopreventive technology with emergence of many nano encapsulated formulations of different dietary anticancer agents. This review summarizes the most up-to-date knowledge on the studies performed in nanochemoprevention, their proposed use in the clinic and future directions in which this field is heading. As the knowledge of the dynamics of nano encapsulation evolves, it is expected that researchers will bring forward newer and far more superior nanochemopreventive agents that may become standard drugs for different cancers. PMID:24212623

  20. Optical absorption and photocurrent enhancement in semi-insulating gallium arsenide by femtosecond laser pulse surface microstructuring.

    PubMed

    Zhao, Zhen-Yu; Song, Zhi-Qiang; Shi, Wang-Zhou; Zhao, Quan-Zhong

    2014-05-19

    We observe an enhancement of optical absorption and photocurrent from semi-insulating gallium arsenide (SI-GaAs) irradiated by femtosecond laser pulses. The SI-GaAs wafer is treated by a regeneratively amplified Ti: Sapphire laser of 120 fs laser pulse at 800 nm wavelength. The laser ablation induced 0.74 μm periodic ripples, and its optical absorption-edge is shifted to a longer wavelength. Meanwhile, the steady photocurrent of irradiated SI-GaAs is found to enhance 50%. The electrical properties of samples are calibrated by van der Pauw method. It is found that femtosecond laser ablation causes a microscale anti-reflection coating surface which enhances the absorption and photoconductivity.

  1. Experimental quantification of useful and parasitic absorption of light in plasmon-enhanced thin silicon films for solar cells application

    PubMed Central

    Morawiec, Seweryn; Holovský, Jakub; Mendes, Manuel J.; Müller, Martin; Ganzerová, Kristina; Vetushka, Aliaksei; Ledinský, Martin; Priolo, Francesco; Fejfar, Antonin; Crupi, Isodiana

    2016-01-01

    A combination of photocurrent and photothermal spectroscopic techniques is applied to experimentally quantify the useful and parasitic absorption of light in thin hydrogenated microcrystalline silicon (μc-Si:H) films incorporating optimized metal nanoparticle arrays, located at the rear surface, for improved light trapping via resonant plasmonic scattering. The photothermal technique accounts for the total absorptance and the photocurrent signal accounts only for the photons absorbed in the μc-Si:H layer (useful absorptance); therefore, the method allows for independent quantification of the useful and parasitic absorptance of the plasmonic (or any other) light trapping structure. We demonstrate that with a 0.9 μm thick absorber layer the optical losses related to the plasmonic light trapping in the whole structure are insignificant below 730 nm, above which they increase rapidly with increasing illumination wavelength. An average useful absorption of 43% and an average parasitic absorption of 19% over 400–1100 nm wavelength range is measured for μc-Si:H films deposited on optimized self-assembled Ag nanoparticles coupled with a flat mirror (plasmonic back reflector). For this sample, we demonstrate a significant broadband enhancement of the useful absorption resulting in the achievement of 91% of the maximum theoretical Lambertian limit of absorption. PMID:26935322

  2. Experimental quantification of useful and parasitic absorption of light in plasmon-enhanced thin silicon films for solar cells application

    NASA Astrophysics Data System (ADS)

    Morawiec, Seweryn; Holovský, Jakub; Mendes, Manuel J.; Müller, Martin; Ganzerová, Kristina; Vetushka, Aliaksei; Ledinský, Martin; Priolo, Francesco; Fejfar, Antonin; Crupi, Isodiana

    2016-03-01

    A combination of photocurrent and photothermal spectroscopic techniques is applied to experimentally quantify the useful and parasitic absorption of light in thin hydrogenated microcrystalline silicon (μc-Si:H) films incorporating optimized metal nanoparticle arrays, located at the rear surface, for improved light trapping via resonant plasmonic scattering. The photothermal technique accounts for the total absorptance and the photocurrent signal accounts only for the photons absorbed in the μc-Si:H layer (useful absorptance); therefore, the method allows for independent quantification of the useful and parasitic absorptance of the plasmonic (or any other) light trapping structure. We demonstrate that with a 0.9 μm thick absorber layer the optical losses related to the plasmonic light trapping in the whole structure are insignificant below 730 nm, above which they increase rapidly with increasing illumination wavelength. An average useful absorption of 43% and an average parasitic absorption of 19% over 400–1100 nm wavelength range is measured for μc-Si:H films deposited on optimized self-assembled Ag nanoparticles coupled with a flat mirror (plasmonic back reflector). For this sample, we demonstrate a significant broadband enhancement of the useful absorption resulting in the achievement of 91% of the maximum theoretical Lambertian limit of absorption.

  3. Absorption of the nerve agent VX (O-ethyl-S-[2(di-isopropylamino)ethyl] methyl phosphonothioate) through pig, human and guinea pig skin in vitro.

    PubMed

    Dalton, Christopher H; Hattersley, Ian J; Rutter, Stephen J; Chilcott, Robert P

    2006-12-01

    The physico-chemical properties of VX make the skin the most likely route of absorption into the human body. The development of effective medical countermeasures against such percutaneous threat agents relies on the use of appropriate animal models, as the inherent toxicity of nerve agents precludes the use of human volunteers. Previous studies have characterised the mechanism of nerve agent toxicity in rodent models, however, it is generally accepted that one of the most appropriate animal models for human skin absorption is the domestic pig. The purpose of the present study was to measure and compare the skin absorption kinetics of VX in vitro using pig, human and guinea pig skin to highlight any potential species differences in skin permeability. When undiluted VX was applied directly to the skin, the permeability of guinea pig skin was approximately 7-fold greater than human skin. There was no significant difference in the permeability of pig and human skin. When VX diluted with isopropyl alcohol was applied to the skin, the permeability of guinea pig skin was approximately 4-fold greater than human skin. There was no significant difference in the permeability of pig and human skin. From this data it may be inferred that dermatomed, abdominal pig skin is an appropriate model for the human skin absorption of VX.

  4. In vitro and in vivo percutaneous absorption of seleno-L-methionine, an antioxidant agent, and other selenium species

    PubMed Central

    Lin, Chih-hung; Fang, Chia-lang; Al-suwayeh, Saleh A; Yang, Shih-yun; Fang, Jia-you

    2011-01-01

    Aim: To investigate the in vitro and in vivo percutaneous absorption of seleno-L-methionine (Se-L-M), an ultraviolet (UV)-protecting agent, from aqueous solutions. Methods: Aqueous solutions of Se-L-M were prepared in pH 4, 8, and 10.8 buffers. The pH 8 buffer contained 30% glycerol, propylene glycol (PG) and polyethylene glycol (PEG) 400. The in vitro skin permeation of Se-L-M via porcine skin and nude mouse skin was measured and compared using Franz diffusion cells. The in vivo skin tolerance study was performed, which examined transepidermal water loss (TEWL), skin pH and erythema. Results: In the excised porcine skin, the flux was 0.1, 11.4 and 8.2 μg·cm−2·h−1 for the pH 4, 8, and 10.8 buffers, respectively. A linear correlation between the flux and skin deposition was determined. According to permeation across skin with different treatments (stripping, delipidation, and ethanol treatments), it was determined that the intracellular route comprised the predominant pathway for Se-L-M permeation from pH 8 buffer. Aqueous solutions of seleno-DL-methionine (Se-DL-M), selenium sulfide and selenium-containing quantum dot nanoparticles were also used as donor systems. The DL form showed a lower flux (7.0 vs 11.4 μg·cm−2·h−1) and skin uptake (23.4 vs 47.3 μg/g) as compared to the L form, indicating stereoselective permeation of this compound. There was no or only negligible permeation of selenium sulfide and quantum dots into and across the skin. With in vivo topical application for 4 and 8 h, the skin deposition of Se-L-M was about 7 μg/g, and values were comparable to each other. The topical application of Se-L-M for up to 5 d did not caused apparent skin irritation. However, slight inflammation of the dermis was noted according to the histopathological examination. Conclusion: Se-L-M was readily absorbed by the skin in both the in vitro and in vivo experiments. The established profiles of Se-L-M skin absorption will be helpful in developing topical

  5. 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.

  6. Nanoemulsions as novel oral carriers of stiripentol: insights into the protective effect and absorption enhancement

    PubMed Central

    Lu, Rong; Liu, Shan; Wang, Qilin; Li, Xia

    2015-01-01

    Oral administration remains a significant challenge in regards to drugs with serious solubility and stability issues. This article aimed to investigate the suitability of nanoemulsions as oral carriers of stiripentol (STP), an acid-labile drug, for enhancement of stability and bioavailability. STP-loaded nanoemulsions (STP-NEs) were prepared by using a solvent-diffusion/ultrasonication technique. STP-NEs were characterized in a variety of ways such as by particle size, entrapment efficiency, in vitro drug release, and transmission electron microscopy. A bioavailability study was performed in rats after oral administration of either STP-NEs, or commercial formulation (Diacomit®). The resultant nanoemulsions were 146.6 nm in particle size with an entrapment efficiency of 99.47%. It was demonstrated that nanoemulsions significantly improved the biochemical stability and bioavailability of STP. The bioavailability of STP-NEs was up to 206.2% relative to Diacomit®. Nanoemulsions fabricated from poly(ethylene glycol) monooleate/medium-chain triglycerides exhibited excellent performance in drug stabilization and absorption enhancement. The results suggest that STP-NEs are a promising means to solve the problems associated with stability and solubility of STP. PMID:26261418

  7. Simultaneous enhancements in photon absorption and charge transport of bismuth vanadate photoanodes for solar water splitting

    NASA Astrophysics Data System (ADS)

    Kim, Tae Woo; Ping, Yuan; Galli, Giulia A.; Choi, Kyoung-Shin

    2015-10-01

    n-Type bismuth vanadate has been identified as one of the most promising photoanodes for use in a water-splitting photoelectrochemical cell. The major limitation of BiVO4 is its relatively wide bandgap (~2.5 eV), which fundamentally limits its solar-to-hydrogen conversion efficiency. Here we show that annealing nanoporous bismuth vanadate electrodes at 350 °C under nitrogen flow can result in nitrogen doping and generation of oxygen vacancies. This gentle nitrogen treatment not only effectively reduces the bandgap by ~0.2 eV but also increases the majority carrier density and mobility, enhancing electron-hole separation. The effect of nitrogen incorporation and oxygen vacancies on the electronic band structure and charge transport of bismuth vanadate are systematically elucidated by ab initio calculations. Owing to simultaneous enhancements in photon absorption and charge transport, the applied bias photon-to-current efficiency of nitrogen-treated BiVO4 for solar water splitting exceeds 2%, a record for a single oxide photon absorber, to the best of our knowledge.

  8. Simultaneous enhancements in photon absorption and charge transport of bismuth vanadate photoanodes for solar water splitting.

    PubMed

    Kim, Tae Woo; Ping, Yuan; Galli, Giulia A; Choi, Kyoung-Shin

    2015-10-26

    n-Type bismuth vanadate has been identified as one of the most promising photoanodes for use in a water-splitting photoelectrochemical cell. The major limitation of BiVO4 is its relatively wide bandgap (∼2.5 eV), which fundamentally limits its solar-to-hydrogen conversion efficiency. Here we show that annealing nanoporous bismuth vanadate electrodes at 350 °C under nitrogen flow can result in nitrogen doping and generation of oxygen vacancies. This gentle nitrogen treatment not only effectively reduces the bandgap by ∼0.2 eV but also increases the majority carrier density and mobility, enhancing electron-hole separation. The effect of nitrogen incorporation and oxygen vacancies on the electronic band structure and charge transport of bismuth vanadate are systematically elucidated by ab initio calculations. Owing to simultaneous enhancements in photon absorption and charge transport, the applied bias photon-to-current efficiency of nitrogen-treated BiVO4 for solar water splitting exceeds 2%, a record for a single oxide photon absorber, to the best of our knowledge.

  9. Simultaneous enhancements in photon absorption and charge transport of bismuth vanadate photoanodes for solar water splitting

    PubMed Central

    Kim, Tae Woo; Ping, Yuan; Galli, Giulia A.; Choi, Kyoung-Shin

    2015-01-01

    n-Type bismuth vanadate has been identified as one of the most promising photoanodes for use in a water-splitting photoelectrochemical cell. The major limitation of BiVO4 is its relatively wide bandgap (∼2.5 eV), which fundamentally limits its solar-to-hydrogen conversion efficiency. Here we show that annealing nanoporous bismuth vanadate electrodes at 350 °C under nitrogen flow can result in nitrogen doping and generation of oxygen vacancies. This gentle nitrogen treatment not only effectively reduces the bandgap by ∼0.2 eV but also increases the majority carrier density and mobility, enhancing electron–hole separation. The effect of nitrogen incorporation and oxygen vacancies on the electronic band structure and charge transport of bismuth vanadate are systematically elucidated by ab initio calculations. Owing to simultaneous enhancements in photon absorption and charge transport, the applied bias photon-to-current efficiency of nitrogen-treated BiVO4 for solar water splitting exceeds 2%, a record for a single oxide photon absorber, to the best of our knowledge. PMID:26498984

  10. PMSE strength during enhanced D region electron densities: Faraday rotation and absorption effects at VHF frequencies

    NASA Astrophysics Data System (ADS)

    Chau, Jorge L.; Röttger, Jürgen; Rapp, Markus

    2014-10-01

    In this paper we study the effects of absorption and Faraday rotation on measurements of polar mesosphere summer echoes (PMSE). We found that such effects can produce significant reduction of signal-to-noise ratio (SNR) when the D region electron densities (Ne) are enhanced, and VHF radar systems with linearly polarized antennas are used. In particular we study the expected effects during the strong solar proton event (SPE) of July 2000, also known as the Bastille day flare event. During this event, a strong anti-correlation between the PMSE SNR and the D-region Ne was found over three VHF radar sites at high latitudes: Andøya, Kiruna, and Svalbard. This anti-correlation has been explained (a) in terms of transport effects due to strong electric fields associated to the SPE and (b) due to a limited amount of aerosol particles as compared to the amount of D-region electrons. Our calculations using the Ne profiles used by previous researchers explain most, if not all, of the observed SNR reduction in both time (around the SPE peak) and altitude. This systematic effect, particularly the Faraday rotation, should be recognized and tested, and possibly avoided (e.g., using circular polarization), in future observations during the incoming solar maximum period, to contribute to the understanding of PMSE during enhanced D region Ne.

  11. Fabrication of Au@Ag core-shell NPs as enhanced CT contrast agents with broad antibacterial properties.

    PubMed

    Huo, Da; He, Jian; Li, Hui; Yu, Haiping; Shi, Tingting; Feng, Yahui; Zhou, Zhengyang; Hu, Yong

    2014-05-01

    Au@Ag core-shell nanoparticles (NPs) integrating both antibacterial and X-ray attenuation capabilities were facilely synthesized in aqueous solution. These NPs modified with methoxy-PEG-SH (m-PEG) on the surface rendered them favorable dispersity and stability in water, resulting in enhancement of their blood circulation time. X-ray photoelectron spectroscope (XPS) and high-resolution transmission electron microscope (HRTEM) results confirmed the core-shell structure of m-PEG-Au@Ag NPs. The m-PEG-Au@Ag NPs showed low cytotoxicity and strong X-ray absorption potency in vitro. Further in vivo study showed that as-synthesized NPs offered a pronounced contrast and prolonged their circulation time in the blood stream with negligible toxic effect in vivo. Besides, m-PEG-Au@Ag NPs had significant bacteriostatic effect toward common bacteria like Escherichia coli and Staphylococcus aureus as demonstrated by broth dilution assay. Given their low-cytotoxicity and high CT attenuation efficacy, m-PEG-Au@Ag NPs had a promising potential for use as CT enhancing and antibacterial agents.

  12. Blockade of constitutively activated ERK signaling enhances cytotoxicity of microtubule-destabilizing agents in tumor cells.

    PubMed

    Tanimura, Susumu; Uchiyama, Aya; Watanabe, Kazushi; Yasunaga, Masahiro; Inada, Yoshiyuki; Kawabata, Takumi; Iwashita, Ken-Ichi; Noda, Sinji; Ozaki, Kei-Ichi; Kohno, Michiaki

    2009-01-16

    The extracellular signal-regulated kinase (ERK) signaling pathway is constitutively activated in many human tumor cell types. Given the cytoprotective role of this pathway, we examined whether its specific blockade might sensitize human tumor cells to the induction of apoptosis by various anticancer drugs. Although blockade of ERK signaling alone did not induce substantial cell death, it resulted in marked and selective enhancement of the induction of apoptosis by microtubule-destabilizing agents in tumor cells in which the ERK pathway is constitutively activated. The synergistic activation of c-Jun NH(2)-terminal kinase by the combination of an ERK pathway inhibitor and a microtubule-destabilizing agent appeared to be responsible, at least in part, for this effect. These results suggest that administration of the combination of an ERK pathway inhibitor and a microtubule-destabilizing agent is a potential chemotherapeutic strategy for the treatment of tumor cells with constitutive activation of the ERK pathway.

  13. Agents.

    PubMed

    Chambers, David W

    2002-01-01

    Although health care is inherently an economic activity, it is inadequately described as a market process. An alternative, grounded in organizational economic theory, is to view professionals and many others as agents, contracted to advance the best interests of their principals (patients). This view untangles some of the ethical conflicts in dentistry. It also helps identify major controllable costs in dentistry and suggests that dentists can act as a group to increase or decrease agency costs, primarily by controlling the bad actors who damage the value of all dentists.

  14. Resveratrol enhances the inotropic effect but inhibits the proarrhythmic effect of sympathomimetic agents in rat myocardium

    PubMed Central

    2017-01-01

    Background Resveratrol is a cardioprotective agent with known antiarrhythmic effects that has recently been shown to inhibit phosphodiesterase (PDE) enzyme activity. Thus, it is possible that resveratrol increases the inotropic effect of sympathomimetic agents, as PDE inhibitors do but, unlike other PDE inhibitors, its effect may not be accompanied by proarrhythmia due to its antiarrhythmic action. This work is aimed to test this hypothesis. Methods This is an “in vitro” concentration-response relationship study. The effects of noradrenaline, tyramine and isoproterenol, alone or in combination with either resveratrol or with the typical PDE inhibitor 3-isobutylmethylxantine (IBMX), were studied in electrically driven strips of right ventricle or in the spontaneously beating free wall of the right ventricle of rat heart in order to investigate inotropic or proarrhythmic effects respectively. Also, the effects of resveratrol or IBMX on the sinoatrial node rate were examined in the isolated right atria of rat heart. Results Resveratrol (10 µM and 100 µM) produces a leftward shift in the concentration-response curves for the contractile effects of noradrenaline, tyramine or isoproterenol and reduces the –log EC50 values of these three agents. IBMX produces similar effects. The spontaneous ventricular beating rate was increased by all three compounds, an effect that was further enhanced by the addition of IBMX. In contrast, resveratrol (100 µM) abolished the effects of these sympathomimetic agents on the ventricular rate. Resveratrol (1–100 µM) had no effect on the sinoatrial node rate, while IBMX produce a concentration dependent sinoatrial tachycardia. Discussion Taken together, the finding, indicate that resveratrol, like the PDE inhibitor IBMX enhances the contractile effects of sympathomimetic agents but, in contrast to IBMX, it does not enhance their proarrhythmic effect or produce sinoatrial tachycardia. This is most probably consequence of the

  15. Enhanced oral absorption of 20(S)-protopanaxadiol by self-assembled liquid crystalline nanoparticles containing piperine: in vitro and in vivo studies

    PubMed Central

    Jin, Xin; Zhang, Zhen-hai; Sun, E; Tan, Xiao-bin; Li, Song-lin; Cheng, Xu-dong; You, Ming; Jia, Xiao-bin

    2013-01-01

    Background 20(S)-protopanaxadiol (PPD), similar to several other anticancer agents, has low oral absorption and is extensively metabolized. These factors limit the use of PPD for treatment of human diseases. Methods In this study, we used cubic nanoparticles containing piperine to improve the oral bioavailability of PPD and to enhance its absorption and inhibit its metabolism. Cubic nanoparticles loaded with PPD and piperine were prepared by fragmentation of glyceryl monoolein (GMO)/poloxamer 407 bulk cubic gel and verified using transmission electron microscopy and differential scanning calorimetry. We evaluated the in vitro release of PPD from these nanoparticles and its absorption across the Caco-2 cell monolayer model, and subsequently, we examined the bioavailability and metabolism of PPD and its nanoparticles in vivo. Results The in vitro release of PPD from these nanoparticles was less than 5% at 12 hours. PPD-cubosome and PPD-cubosome loaded with piperine (molar ratio PPD/piperine, 1:3) increased the apical to basolateral permeability values of PPD across the Caco-2 cell monolayer from 53% to 64%, respectively. In addition, the results of a pharmacokinetic study in rats showed that the relative bioavailabilities of PPD-cubosome [area under concentration–time curve (AUC)0–∞] and PPD-cubosome containing piperine (AUC0–∞) compared to that of raw PPD (AUC0–∞) were 166% and 248%, respectively. Conclusion The increased bioavailability of PPD-cubosome loaded with piperine is due to an increase in absorption and inhibition of metabolism of PPD by cubic nanoparticles containing piperine rather than because of improved release of PPD. The cubic nanoparticles containing piperine may be a promising oral carrier for anticancer drugs with poor oral absorption and that undergo extensive metabolism by cytochrome P450. PMID:23426652

  16. Characterization of chemical warfare G-agent hydrolysis products by surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Inscore, Frank E.; Gift, Alan D.; Maksymiuk, Paul; Farquharson, Stuart

    2004-12-01

    The United States and its allies have been increasingly challenged by terrorism, and since the September 11, 2001 attacks and the war in Afghanistan and Iraq, homeland security has become a national priority. The simplicity in manufacturing chemical warfare agents, the relatively low cost, and previous deployment raises public concern that they may also be used by terrorists or rogue nations. We have been investigating the ability of surface-enhanced Raman spectroscopy (SERS) to detect extremely low concentrations (e.g. part-per-billion) of chemical agents, as might be found in poisoned water. Since trace quantities of nerve agents can be hydrolyzed in the presence of water, we have expanded our studies to include such degradation products. Our SERS-active medium consists of silver or gold nanoparticles incorporated into a sol-gel matrix, which is immobilized in a glass capillary. The choice of sol-gel precursor allows controlling hydrophobicity, while the porous silica network offers a unique environment for stabilizing the SERS-active metals. Here we present the use of these metal-doped sol-gels to selectively enhance the Raman signal of the hydrolyzed products of the G-series nerve agents.

  17. Intelligent Agent-Based Intrusion Detection System Using Enhanced Multiclass SVM

    PubMed Central

    Ganapathy, S.; Yogesh, P.; Kannan, A.

    2012-01-01

    Intrusion detection systems were used in the past along with various techniques to detect intrusions in networks effectively. However, most of these systems are able to detect the intruders only with high false alarm rate. In this paper, we propose a new intelligent agent-based intrusion detection model for mobile ad hoc networks using a combination of attribute selection, outlier detection, and enhanced multiclass SVM classification methods. For this purpose, an effective preprocessing technique is proposed that improves the detection accuracy and reduces the processing time. Moreover, two new algorithms, namely, an Intelligent Agent Weighted Distance Outlier Detection algorithm and an Intelligent Agent-based Enhanced Multiclass Support Vector Machine algorithm are proposed for detecting the intruders in a distributed database environment that uses intelligent agents for trust management and coordination in transaction processing. The experimental results of the proposed model show that this system detects anomalies with low false alarm rate and high-detection rate when tested with KDD Cup 99 data set. PMID:23056036

  18. Surface-enhanced infrared absorption spectroscopy (SEIRAS) to probe monolayers of membrane proteins.

    PubMed

    Ataka, Kenichi; Stripp, Sven Timo; Heberle, Joachim

    2013-10-01

    Surface-enhanced infrared absorption spectroscopy (SEIRAS) represents a variation of conventional infrared spectroscopy and exploits the signal enhancement exerted by the plasmon resonance of nano-structured metal thin films. The surface enhancement decays in about 10nm with the distance from the surface and is, thus, perfectly suited to selectively probe monolayers of biomembranes. Peculiar to membrane proteins is their vectorial functionality, the probing of which requires proper orientation within the membrane. To this end, the metal surface used in SEIRAS is chemically modified to generate an oriented membrane protein film. Monolayers of uniformly oriented membrane proteins are formed by tethering His-tagged proteins to a nickel nitrilo-triacetic acid (Ni-NTA) modified gold surface and SEIRAS commands molecular sensitivity to probe each step of surface modification. The solid surface used as plasmonic substrate for SEIRAS, can also be employed as an electrode to investigate systems where electron transfer reactions are relevant, like e.g. cytochrome c oxidase or plant-type photosystems. Furthermore, the interaction of these membrane proteins with water-soluble proteins, like cytochrome c or hydrogenase, is studied on the molecular level by SEIRAS. The impact of the membrane potential on protein functionality is verified by monitoring light-dark difference spectra of a monolayer of sensory rhodopsin (SRII) at different applied potentials. It is demonstrated that the interpretations of all of these experiments critically depend on the orientation of the solid-supported membrane protein. Finally, future directions of SEIRAS including cellular systems are discussed. This article is part of a Special Issue entitled: FTIR in membrane proteins and peptide studies.

  19. The use of low molecular weight protamine chemical chimera to enhance monomeric insulin intestinal absorption.

    PubMed

    He, Huining; Sheng, Jianyong; David, Allan E; Kwon, Young Min; Zhang, Jian; Huang, Yongzhuo; Wang, Jianxin; Yang, Victor C

    2013-10-01

    Although oral delivery of insulin offers a number of unmatched advantages, it nevertheless is beset by the poor permeability of insulin molecules through the epithelial cell membranes of the intestinal mucosal layer. We previously reported the development of low molecular weight protamine (LMWP) as a non-toxic yet potent cell-penetrating peptide, of which via covalent linkage was capable of translocating protein cargos through the membranes of almost all cell types. It is therefore hypothesized that LMWP could be practically employed as a safe and effective tool to deliver insulin across the intestinal mucosal membrane, thereby augmenting its absorption through the GI tract. However, formulating 1:1 monomeric insulin/LMWP conjugate presents a tall order of challenge, as the acidic insulin and basic LMWP would automatically form tight aggregates through electrostatic interactions. In this paper, we developed an innovative conjugation strategy to solve this problem, by using succinimidyl-[(N-maleimidopropionamido)-polyethyleneglycol] ester (NHS-PEG-MAL) as an intermediate cross-linker during the coupling process. Both SDS-PAGE and MALDI-TOF mass spectroscopy confirmed the formation of a homogenous, monomeric (1:1 ratio) insulin/LMWP conjugate without encountering the conventional problem of substrate aggregation. Cell culture studies demonstrated that transport of the Insulin-PEG-LMWP conjugate across the intestinal mucosal monolayer was augmented by almost five-folds compared to native insulin. Furthermore, results from the in situ loop absorption tests in rats showed that systemic pharmacological bioavailability of insulin was significantly enhanced after its conjugation with LMWP. Overall, the presented chemical conjugation with LMWP could offer a reliable and safe means to improve the intestinal permeability of therapeutic peptides/proteins, shedding light of the possibility for their effective oral delivery.

  20. The Use of Low Molecular Weight Protamine Chemical Chimera to Enhance Monomeric Insulin Intestinal Absorption

    PubMed Central

    He, Huining; Sheng, Jianyong; David, Allan E.; Kwon, Young Min; Zhang, Jian; Huang, Yongzhuo; Wang, Jianxin; Yang, Victor C.

    2013-01-01

    Although oral delivery of insulin offers a number of unmatched advantages, it nevertheless is beset by the poor permeability of insulin molecules through the epithelial cell membranes of the intestinal mucosal layer. We previously reported the development of low molecular weight protamine (LMWP) as a nontoxic yet potent cell penetrating peptide, of which via covalent linkage was capable of translocating protein cargos through the membranes of almost all cell types. It is therefore hypothesized that LMWP could be practically employed as a safe and effective tool to deliver insulin across the intestinal mucosal membrane, thereby augmenting its absorption through the GI tract. However, formulating 1:1 monomeric insulin/LMWP conjugate presents a tall order of challenge, as the acidic insulin and basic LMWP would automatically form tight aggregates through electrostatic interactions. In this paper, we developed an innovative conjugation strategy to solve this problem, by using succinimidyl-[(N-maleimidopropionamido)-polyethyleneglycol] ester (NHS-PEG-MAL) as an intermediate cross-linker during the coupling process. Both SDS-PAGE and MALDI-TOF mass spectroscopy confirmed the formation of a homogeneous, monomeric (1:1 ratio) insulin/LMWP conjugate without encountering the conventional problem of substrate aggregation. Cell culture studies demonstrated that transport of the Insulin-PEG-LMWP conjugate across the intestinal mucosal monolayer was augmented by almost five folds compared to native insulin. Furthermore, results from the in situ loop absorption tests in rats showed that systemic pharmacological bioavailability of insulin was significantly enhanced after its conjugation with LMWP. Overall, the presented chemical conjugation with LMWP could offer a reliable and safe means to improve the intestinal permeability of therapeutic peptides/proteins, shedding light of the possibility for their effective oral delivery. PMID:23863452

  1. [Dithiobis-succinimidyl propionate on gold island films: surface-enhanced infrared absorption spectroscopy study].

    PubMed

    Guo, Hao; Ding, Li; Zhang, Tian-Jie; Mao, Yan-Li

    2013-05-01

    Dithiobis-succinimidyl propionate (DTSP), an important homobifunctional crosslinker, has been widely used for the covalent immobilization of proteins onto solid supports by amine coupling. In the present study, adsorption of DTSP on vacuum-deposited gold island films was analyzed by means of surface-enhanced infrared absorption spectroscopy (SEIRAS). For the sake of a reliable assignment of the vibrational spectra, IR intensity of the adsorption model of TSP on one gold surface was calculated using density functional theory (DFT) at the Beck' s three-parameter Lee-Yang-Parr (B3LYP) level with the LANL2DZ basis set. SEIRAS and multiple-angle-of-incidence polarization infrared reflection-absorption spectroscopy indicated that TSP is arranged orderly in a tilted fashion with a dihedral angle of 65 degrees between the plane of succinimidyl ring and the gold surface. The binding kinetics revealed that that the time constant of self-assembly of the TSP layer is 220 sec. Furthermore, the coupling process of amino-nitrilotriacetic acid (ANTA) with surface-bound TSP monolayer was monitored in situ by SEIRAS. Three negative bands observed at 1 807, 1 776, and 1 728 cm(-1) respectively provided direct evidence for the reaction of the succinimidyl ester. The appearance of one intense band at 1 566 cm(-1) gave a clear support for the presence of the cross-link between ANTA and TSP. We hope that the results in current investigation will contribute to the better understanding of properties of DTSP and related reactions at the molecular level.

  2. Enhancement of biological control agents for use against forest insect pests and diseases through biotechnology

    NASA Technical Reports Server (NTRS)

    Slavicek, James M.

    1991-01-01

    Research and development efforts in our research group are focused on the generation of more efficacious biological control agents through the techniques of biotechnology for use against forest insect pests and diseases. Effective biological controls for the gypsy moth and for tree fungal wilt pathogens are under development. The successful use of Gypchek, a formulation of the Lymantria dispar nuclear polyhedrosis virus (LdNPV), in gypsy moth control programs has generated considerable interest in that agent. As a consequence of its specificity, LdPNV has negligible adverse ecological impacts compared to most gypsy moth control agents. However, LdNPV is not competitive with other control agents in terms of cost and efficacy. We are investigating several parameters of LdNPV replication and polyhedra production in order to enhance viral potency and efficacy thus mitigating the current disadvantages of LdNPV for gypsy moth control, and have identified LdNPV variants that will facilitate these efforts. Tree endophytic bacteria that synthesize antifungal compounds were identified and an antibiotic compound from one of these bacteria was characterized. The feasibility of developing tree endophytes as biological control agents for tree vascular fungal pathogens is being investigated.

  3. Solvent dependence of two-photon absorption spectra of the enhanced green fluorescent protein (eGFP) chromophore

    NASA Astrophysics Data System (ADS)

    Hosoi, Haruko; Tayama, Ryo; Takeuchi, Satoshi; Tahara, Tahei

    2015-06-01

    Two-photon absorption spectra of 4‧-hydroxybenzylidene-2,3-dimethylimidazolinone, a model chromophore of enhanced green fluorescent protein (eGFP), were measured in various solvents. The two-photon absorption band of its anionic form is markedly blue-shifted from the corresponding one-photon absorption band in all solvents. Moreover, the magnitude of the blue shift varies largely depending on the solvent, which does not accord with the assignment of the two-photon absorption band to the transitions to the vibrationally excited S1 state. Our finding is readily rationalized by considering overlapping contributions of the S1 ← S0 and S2 ← S0 transitions, suggesting the involvement of the S2 state also in two-photon fluorescence of eGFP.

  4. Enhancement of optical absorption in thin-film solar cells through the excitation of higher-order nanoparticle plasmon modes.

    PubMed

    Akimov, Yu A; Koh, W S; Ostrikov, K

    2009-06-08

    Recent research in the rapidly emerging field of plasmonics has shown the potential to significantly enhance light trapping inside thin-film solar cells by using metallic nanoparticles. In this article it is demonstrated the plasmon enhancement of optical absorption in amorphous silicon solar cells by using silver nanoparticles. Based on the analysis of the higher-order surface plasmon modes, it is shown how spectral positions of the surface plasmons affect the plasmonic enhancement of thin-film solar cells. By using the predictive 3D modeling, we investigate the effect of the higher-order modes on that enhancement. Finally, we suggest how to maximize the light trapping and optical absorption in the thin-film cell by optimizing the nanoparticle array parameters, which in turn can be used to fine tune the corresponding surface plasmon modes.

  5. Mechanism for enhancement effect of lipid disperse system on percutaneous absorption.

    PubMed

    Ogiso, T; Niinaka, N; Iwaki, M

    1996-01-01

    To clarify the mechanism involved in the enhancement effect of lipid disperse systems (LDS) on percutaneous absorption, the effect of the LDSs of betahistine (BH), prepared using egg phosphatidylcholine (EPC, phase transition temperature, tau m, -15 to -17 degrees C) or hydrogenated soybean phosphatidylcholine (HSPC, tau m, 50 to 60 degrees C), cholesterol, and dicetylphosphate, on the percutaneous absorption of BH, the amount of skin lipids (ceramides, triglycerides, and phospholipids), the fluidity of skin lipids, and the partitioning of LDS-BH into the skin layers were investigated using Wistar and hairless rats. Also examined was whether the LDS penetrated through the stratum corneum (SC) or follicles, using a fluorescent probe (Nile Red). The plasma concentrations of BH were much higher and more sustained after application of a gel formulation containing EPC-LDS and D-limonene (prep. 2) than those after the non-LDS formulation containing D-limonene (prep. 1), whereas the plasma levels after application of a formulation containing HSPC-LDS (prep. 5) were not largely increased compared with those after prep. 1. The content of ceramides (intercellular lipids) and triglycerides (sebaceous gland lipides) in the SC were dramatically decreased by the treatment with prep. 1 and prep. 2, with the more decreased levels of these lipids by the treatment with prep. 2. The phospholipid content of the SC was enhanced by 2-fold following the prep. 2 treatment, indicating the extensive incorporation of LDS lipids into the SC. The histochemical examination of the skin, following application of EPC-LDS with a fluorescent probe, indicated that the LDS lipids penetrated rapidly through the SC and follicles into the viable skins. The fluidity of the SC lipids was dramatically increased following the treatment with the fluid EPC-LDS, whereas the fluidity was significantly decreased by the solid HSPC-LDS. The BH in each skin layer was also significantly increased by the treatment

  6. A Novel Self-Microemulsifying System for the Simultaneous Delivery and Enhanced Oral Absorption of Curcumin and Resveratrol.

    PubMed

    Jaisamut, Patcharawalai; Wiwattanawongsa, Kamonthip; Wiwattanapatapee, Ruedeekorn

    2017-03-01

    The use of curcumin and resveratrol in combination has now become increasingly of interest because of their synergistic effects as therapeutic agents for various diseases, especially cancer. To overcome the poor oral bioavailability of both compounds and improve patient compliance, a novel self-microemulsifying formulation containing curcumin together with resveratrol was developed. Capryol 90, Cremophor EL, and Labrasol were selected as the oil, surfactant, and co-surfactant in the formulation, respectively, based on the solubility study of both compounds. More than 70 % and 80 % of curcumin and resveratrol, respectively, were released in 20 min. The formulation formed a fine oil in water microemulsion with droplet sizes in aqueous media of 15-20 nm. In addition, the formulation containing curcumin and resveratrol showed greater antioxidant activity than that of the formulations with individual compounds, while the cytotoxic activity against HT-29 of the co-formulation (IC50 = 18.25 µM; curcumin and resveratrol in the ratio 1 : 1) was less than the formulation with only curcumin (IC50 = 30.1 µM) and only resveratrol (IC50 = 25.4 µM). After oral administration to rabbits, the self-microemulsifying formulation containing curcumin together with resveratrol increased the total plasma concentrations of curcumin and resveratrol by 10-fold and 6-fold, respectively, compared to the unformulated combination. This study clearly demonstrated the potential use of the self-microemulsifying formulation for co-delivery, and enhanced oral absorption of poorly water-soluble natural compounds. In addition, the combination was found to produce synergistic antioxidant activity and cytotoxicity against HT-29 cells.

  7. Wide-angle polarization-free plasmon-enhanced light absorption in perovskite films using silver nanowires.

    PubMed

    Wang, Geng; Meng, Ke; He, Zhen; Wu, Longlong; Liu, Zhou; Wang, Xiao; Li, Wenqin; Tai, Renzhong; Yu, Shu-Hong; Chen, Gang

    2017-02-20

    Since the successful implementation of organic-inorganic hybrid perovskites as light-absorbing materials, stunning progresses have been made towards the efficiency boost of perovskite solar cells. To build upon these successes, further impetus may derive from revisits to the intrinsic properties of perovskites, such as their optical properties. Herein, we introduce periodic Ag nanowire (AgNW) structures into perovskite films to optimize their solar absorption efficiency through plasmonic interactions. Numerical simulations show a remarkable integrated solar absorption enhancement of 25.9% attained by incorporating properly tailored AgNW arrays into perovskite films. The AgNW crosses are further introduced to achieve polarization-independent light harvesting capability. The omnidirectional light absorption enhancement ability of the AgNW embedded perovskite films is also demonstrated.

  8. Calcium absorption is not consistently enhanced by maintaining serum 25-hydroxyvitamin D levels > 50 or 80 nmol/L

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing serum 25-hydroxyvitamin D (25-OHD) in adults may enhance calcium absorption (Ca-abs). Targeting of 25-OHD values for the entire population has been widely advocated recently with goals of 25-OHD of at least 50 or 80 nmol/L advocated. There are few pediatric data that relate 25-OHD to Ca-a...

  9. Enhancing the sensitivity of mid-IR quantum cascade laser-based cavity-enhanced absorption spectroscopy using RF current perturbation.

    PubMed

    Manfred, Katherine M; Kirkbride, James M R; Ciaffoni, Luca; Peverall, Robert; Ritchie, Grant A D

    2014-12-15

    The sensitivity of mid-IR quantum cascade laser (QCL) off-axis cavity-enhanced absorption spectroscopy (CEAS), often limited by cavity mode structure and diffraction losses, was enhanced by applying a broadband RF noise to the laser current. A pump-probe measurement demonstrated that the addition of bandwidth-limited white noise effectively increased the laser linewidth, thereby reducing mode structure associated with CEAS. The broadband noise source offers a more sensitive, more robust alternative to applying single-frequency noise to the laser. Analysis of CEAS measurements of a CO(2) absorption feature at 1890  cm(-1) averaged over 100 ms yielded a minimum detectable absorption of 5.5×10(-3)  Hz(-1/2) in the presence of broadband RF perturbation, nearly a tenfold improvement over the unperturbed regime. The short acquisition time makes this technique suitable for breath applications requiring breath-by-breath gas concentration information.

  10. Low molecular weight quaternised chitosan (11): in vitro assessment of absorption enhancing properties.

    PubMed

    Jonker-Venter, C; Snyman, D; Janse van Rensburg, C; Jordaan, E; Schultz, C; Steenekamp, J H; Hamman, J H; Kotzé, A F

    2006-04-01

    N-Trimethyl chitosan chloride (TMC; high molecular weight) and N-trimethyl chitosan oligosaccharide (TMO; low molecular weight) with different degrees of quaternisation were synthesised and evaluated for their absorption enhancing properties across mucosal epithelia. These quaternised chitosan derivatives (0.0625% w/v-0.5% w/v) showed a significant decrease in the transepithelial electrical resistance (TEER) of cultured rabbit tracheal epithelial cell monolayers as compared to the control. The degree of quaternisation and concentration of the compounds influenced the extent of the reduction in TEER. Higher degrees of quaternisation and an increase in the concentration of the compound were associated with a more pronounced reduction in the TEER. The TMO derivatives seemed to be more effective in lowering the TEER of tracheal cell monolayers as compared to the TMC polymers. Ciliary beat frequency (CBF) is the main defence mechanism of the respiratory tract and is therefore a useful parameter in evaluating the toxicity of nasally administered drugs and additives. The effect of the synthesised chitosan derivatives on the CBF of human nasal epithelial cells at pH 7.4 was determined by a method based on an analogue contrast enhancement technique. The TMO oligomers exhibited lower inhibition of the CBF of human nasal epithelial cells compared to that of the TMC polymers. It was proposed that this reduced effect on the CBF is due to the lower viscosity and molecular weight of TMO. However, no acute toxicity was found with any of the synthesised chitosan derivatives by means of the CBF tests conducted in this study.

  11. Optical feedback cavity enhanced absorption spectroscopy: effective adjustment of the feedback-phase

    NASA Astrophysics Data System (ADS)

    Habig, J. C.; Nadolny, J.; Meinen, J.; Saathoff, H.; Leisner, T.

    2012-02-01

    Optical-feedback cavity enhanced absorption spectroscopy (OF-CEAS) is a very sensitive technique for the detection of trace amounts of gaseous absorbers. The most crucial parameter in an OF-CEAS setup is the optical phase of the light fed back into the laser source, which is usually controlled by the position of a piezo driven mirror. Various approaches for the analysis of the cavity transmitted light with respect to feedback-phase are presented, and tested on simulated phase and frequency dependent cavity transmission. Finally, we present the performance of a digital signal processor based regulator—employing one of these approaches—in a real OF-CEAS experiment. The results of the simulation show that several algorithms are well suited for the task of control signal generation. They confirm also that with the presented approach, a mode by mode correction of the feedback-phase is possible. Consequently, a regulatory bandwidth of 37 Hz was achieved. This maximum control frequency was limited by the piezo system.

  12. Cavity-enhanced absorption spectroscopy to characterize atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    van Helden, Jean-Pierre; Nave, Andy; Reuter, Stephan; Roepcke, Juergen; Gianella, Michele; Ritchie, Grant

    2016-09-01

    Non-equilibrium atmospheric pressure plasma jets gain more and more interest as their technological applications increase in diverse fields such as material processing and plasma medicine. Hence, it is essential to diagnose the fluxes of the species generated by these plasma sources to identify relevant fundamental processes and to improve process efficiency. Especially for a comprehensive understanding of the kinetics of the transient species involved, high precision measurements of reactive molecular precursors, free radicals and to identify of any short lived species are of crucial importance. However, the detection of transient species in these type of plasmas poses a challenge for diagnostic techniques as the plasmas typically have small dimensions and high density gradients in space and time. We have overcome these limitations by using cavity-enhanced absorption spectroscopy (CEAS). In this contribution, the latest results concerning the detection of transient species in two types of plasma jets employing CEAS in the near- and mid-infrared spectral range will be presented. We will show that with these methods spatially resolved investigations of concentrations in the mm sized effluent of the plasma jet can be achieved.

  13. Sensing the dynamics of oxidative stress using enhanced absorption in protein-loaded random media.

    PubMed

    Suárez, Guillaume; Santschi, Christian; Slaveykova, Vera I; Martin, Olivier J F

    2013-12-09

    Reactive oxygen species play a key role in cell signalling and oxidative stress mechanisms, therefore, sensing their production by living organisms is of fundamental interest. Here we describe a novel biosensing method for extracellular detection of endogenous hydrogen peroxide (H2O2). The method is based on the enhancement of the optical absorption spectrum of the hemoprotein cytochrome c when loaded into a highly scattering random medium. Such a configuration enables, in contrast to existing techniques, non-invasive and dynamic detection of the oxidation of cyt c in the presence of H2O2 with unprecedented sensitivity. Dynamic information on the modification of the cell oxidative status of Chlamydomonas reinhardtii, an aquatic green algae, was obtained under oxidative stress conditions induced by the presence of trace concentrations of Cd(II). Furthermore, the dynamics of H2O2 production was investigated under different lighting conditions confirming the impact of Cd(II) on the photosynthetic activity of those phytoplanktonic cells.

  14. Corn oil and milk enhance the absorption of orally administered allyl isothiocyanate in rats.

    PubMed

    Ippoushi, Katsunari; Ueda, Hiroshi; Takeuchi, Atsuko

    2013-11-15

    Allyl isothiocyanate, a chief component of mustard oil, exhibits anticancer effects in both cultured cancer cells and animal models. The accumulation of the N-acetylcysteine conjugate of allyl isothiocyanate, the final metabolite of allyl isothiocyanate, in urine was evaluated in rats that were orally coadministered allyl isothiocyanate with fluids (e.g., water, green tea, milk, and 10% ethanol) or corn oil. The N-acetylcysteine conjugate of allyl isothiocyanate content in urine when allyl isothiocyanate (2 or 4μmol) was coadministered with corn oil or milk showed a greater increase (1.4±0.22 or 2.7±0.34μmol or 1.2±0.32 or 2.5±0.36μmol, 1.6- to 1.8-fold or 1.5-fold, respectively) than when allyl isothiocyanate (2 or 4μmol) was coadministered with water (0.78±0.10 or 1.7±0.17μmol). This result demonstrates that corn oil and milk enhance the absorption of allyl isothiocyanate in rats.

  15. Cavity-Enhanced Near-Infrared Laser Absorption Spectrometer for the Measurement of Acetonitrile in Breath.

    PubMed

    Gianella, Michele; Ritchie, Grant A D

    2015-07-07

    Elevated concentrations of acetonitrile have been found in the exhaled breath of patients with cystic fibrosis1 and may indicate the severity of their condition or the presence of an accompanying bacterial infection of the airways. There is therefore interest in detecting acetonitrile in exhaled breath. For this purpose, a cavity-enhanced laser absorption spectrometer (λ = 1.65 μm) with a preconcentration stage was built and is described here. The spectrometer has a limit of detection of 72 ppbv and 114 ppbv of acetonitrile in nitrogen and breath, respectively, with a measurement duration of just under 5 min. The preconcentration stage, which employs a carbon molecular sieve and an adsorption/thermal desorption cycle, can increase the acetonitrile concentration by up to a factor 93, thus, lowering the overall limit of detection to approximately 1 ppbv. The suitability of the system for acetonitrile measurements in breath is demonstrated with breath samples taken from the authors, which yielded acetonitrile concentrations of 23 ± 3 ppbv and 29 ± 3 ppbv, respectively.

  16. Broadband light absorption enhancement in moth's eye nanostructured organic solar cells

    NASA Astrophysics Data System (ADS)

    Lan, Weixia; Cui, Yanxia; Yang, Qingyi; Lo, Ming-Fai; Lee, Chun-Sing; Zhu, Furong

    2015-05-01

    A comprehensive study on inverted organic solar cells (OSCs) with a moth's eye nanostructured (MEN) active layer was carried out. Performance of the MEN-based OSCs and the corresponding control planar cells, fabricated with blend of poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-bA] dithiophene-2, 6-diyl][3-fluoro-2-[(2- ethylhexyl) carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7):[6,6]- phenyl-C70- butyric-acid-methyl-ester (PC70BM) was analyzed. The efficiency of the MEN-based OSCs was optimized by adjusting the height of MEN pattern in the active layer. Our experimental and theoretical results reveal that the MEN pattern enhances light absorption in the PTB7:PC70BM active layer, especially over the long wavelength region. This leads to a 7.8% increase in short circuit current density and a 6.1% increase in power conversion efficiency over those of the control planar cell.

  17. Shock-Tube Measurement of Acetone Dissociation Using Cavity-Enhanced Absorption Spectroscopy of CO.

    PubMed

    Wang, Shengkai; Sun, Kai; Davidson, David F; Jeffries, Jay B; Hanson, Ronald K

    2015-07-16

    A direct measurement for the rate constant of the acetone dissociation reaction (CH3COCH3 = CH3CO + CH3) was conducted behind reflected shock wave, utilizing a sub-ppm sensitivity CO diagnostic achieved by cavity-enhanced absorption spectroscopy (CEAS). The current experiment eliminated the influence from secondary reactions and temperature change by investigating the clean pyrolysis of <20 ppm acetone in argon. For the first time, the acetone dissociation rate constant (k1) was directly measured over 5.5 orders of magnitude with a high degree of accuracy: k1 (1004-1494 K, 1.6 atm) = 4.39 × 10(55) T(-11.394) exp(-52 140K/T) ± 24% s(-1). This result was seen to agree with most previous studies and has bridged the gap between their temperature and pressure conditions. The current work also served as an example demonstration of the potential of using the CEAS technique in shock-tube kinetics studies.

  18. Broadband optical absorption enhancement of hexagonal nanoconical frustum arrays texturing for c-Si film solarcells

    NASA Astrophysics Data System (ADS)

    Wangyang, Peihua; Wang, Qingkang; Hu, Kexiang; Wan, Xia; Huang, Kun

    2013-05-01

    In this paper, the optical properties of the silicon hexagonal nanoconical frustum (SiHNF) arrays are theoretically studied via simulation based on the Rigorous Coupled Wave Analysis (RCWA) in detail. The results show that the SiHNF bottom diameter (Dbot) should be equal to the array periodicity for efficient solar energy harvesting, and the optimized light absorption could be realized when the SiHNF height reaches 1000 nm with Dtop equal to100 nm. The optimal SiHNF arrays has the periodicity of 700 nm, the top diameter of 100 nm and the SiHNF height of 1000 nm, yielding an ultimate efficiency of 30.54%, which is more than two times of a 2.33 μm thick Si thin film solar cells. Comparing to nanopillar and square nanoconical frustum structures, the enhanced ultimate efficiency of SiHNF structure is less sensitive to the incident zenith angle and SiHNF top diameter. The possible physical mechanism behind the observation is also explored in thiswork.

  19. Enhancement of pharmacological effects of uricosuric agents by concomitant treatment with pyrazinamide in rats.

    PubMed

    Taniguchi, Tetsuya; Ashizawa, Naoki; Matsumoto, Koji; Iwanaga, Takashi

    2017-03-01

    Our goal was to establish a model for the evaluation of the effects of uricosuric agents and to clarify the underlying mechanism(s). The effects of a uricosuric agent co-treated with pyrazinamide, an anti-tubercular agent, on urate handling were examined in rats. Furthermore, the effects of uricosuric agents on urate uptake were evaluated using the vesicles of rat renal brush-border membrane. Treatment with probenecid, at a dose of 100 mg/kg, significantly increased the urinary urate to creatinine ratio (UUA/UCRE) in pyrazinamide-treated rats although the same treatment did not produce any uricosuric effects in intact rats. In this model, the urinary excretion of pyrazinecarboxylic acid (PZA), an active metabolite of pyrazinamide, was decreased by probenecid and indicated an inverse correlation between urinary excretion of urate and PZA. Furthermore, in the examination using FYU-981, a potent uricosuric agent, a more than 10-fold leftward shift of the dose-response relationship of the uricosuric effect was observed in pyrazinamide-treated rats when compared with intact rats. In the in vitro study, the treatment of the vesicles of rat renal brush-border membrane with PZA produced an increased urate uptake, which was inhibited by uricosuric agents. The pyrazinamide-treated model used in the present study seems to be valuable for the evaluation of uricosurics because of its higher sensitivity to these drugs when compared to intact rats, and this is probably due to the enhanced urate reabsorption accompanied with trans-stimulated PZA transport at the renal brush-border membrane.

  20. Nootropic agents enhance the recruitment of fast GABAA inhibition in rat neocortex.

    PubMed

    Ling, Douglas S F; Benardo, Larry S

    2005-07-01

    It is widely believed that nootropic (cognition-enhancing) agents produce their therapeutic effects by augmenting excitatory synaptic transmission in cortical circuits, primarily through positive modulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptors (AMPARs). However, GABA-mediated inhibition is also critical for cognition, and enhanced GABA function may be likewise therapeutic for cognitive disorders. Could nootropics act through such a mechanism as well? To address this question, we examined the effects of nootropic agents on excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) recorded from layer V pyramidal cells in acute slices of somatosensory cortex. Aniracetam, a positive modulator of AMPA/kainate receptors, increased the peak amplitude of evoked EPSCs and the amplitude and duration of polysynaptic fast IPSCs, manifested as a greater total charge carried by IPSCs. As a result, the EPSC/IPSC ratio of total charge was decreased, representing a shift in the excitation-inhibition balance that favors inhibition. Aniracetam did not affect the magnitude of either monosynaptic IPSCs (mono-IPSCs) recorded in the presence of excitatory amino acid receptor antagonists, or miniature IPSCs (mIPSCs) recorded in the presence of tetrodotoxin. However, the duration of both mono-IPSCs and mIPSCs was prolonged, suggesting that aniracetam also directly modulates GABAergic transmission. Cyclothiazide, a preferential modulator of AMPAR function, enhanced the magnitude and duration of polysynaptic IPSCs, similar to aniracetam, but did not affect mono-IPSCs. Concanavalin A, a kainate receptor modulator, had little effect on EPSCs or IPSCs, suggesting there was no contribution from kainate receptor activity. These findings indicate that AMPAR modulators strengthen inhibition in neocortical pyramidal cells, most likely by altering the kinetics of AMPARs on synaptically connected interneurons and possibly by modulating GABA(A) receptor responses

  1. Coexisted components of Salvia miltiorrhiza enhance intestinal absorption of cryptotanshinone via inhibition of the intestinal P-gp.

    PubMed

    Dai, Haixue; Li, Xiaorong; Li, Xiaoli; Bai, Lu; Li, Yuhang; Xue, Ming

    2012-11-15

    Cryptotanshinone, derived from the roots of Salvia miltiorrhiza Bge and Salvia przewalskii Maxim, is the major active component and possesses significant antibacterial, antidermatophytic, antioxidant, anti-inflammatory and anticancer activities. The objective of this study was to investigate the intestinal absorptive characteristics of cryptotanshinone as well as the absorptive behavior influenced by co-administration of the diterpenoid tanshinones and danxingfang using an in vitro everted rat gut sac model. The results showed a good linear correlation between cryptotanshinone of absorption and the incubation time from 10 to 70min. The concentration dependence showed that a non-linear correlation existed between the cryptotanshinone absorption and the concentration at 100 μg/ml. Coexisting diterpenoid tanshinones and danxingfang could significantly enhance the absorption of cryptotanshinone. Coexisting diterpenoid tanshinones and danxingfang, which influenced cryptotanshinone's absorption, manifested as similar to that of the P-glycoprotein inhibitor. The underlying mechanism of the improvement of oral bioavailability was proposed that coexisting diterpenoid tanshinones and danxingfang could decrease the efflux transport of cryptotanshinone by P-glycoprotein.

  2. Cooperative enhancement of TPA in cruciform double-chain DSB derivation: a femtosecond transient absorption spectra study

    NASA Astrophysics Data System (ADS)

    He, X.; Wang, Y.; Yang, Z.; Ma, Y.; Yang, Y.

    2010-09-01

    Femtosecond time-resolved transient absorption (TA) spectra study was adopted to study the mechanism of the cooperative enhancement of two-photon absorption (TPA) cross section from the linear structure 1,4-di(4'-N,N-diphenylaminostyryl)benzene (DPA-DSB) to its cruciform double-chain dimer DPA-TSB. The results suggested that a non-emissive intramolecular charge-transfer (ICT) state, ICT’, was present upon excitation in the dimer, which was absent in the monomer. The existence of this non-emissive state, indicating the enhancement of the intramolecular charge-transfer of the dimer, should be the reason for the cooperative enhancement of the TPA cross section of the dimer compared to the monomer.

  3. Effects of fasting and/or oxidizing and reducing agents on absorption of neptunium from the gastrointestinal tract of mice and adult or neonatal rats.

    PubMed

    Sullivan, M F; Ruemmler, P S; Ryan, J L

    1984-12-01

    Neptunium-237(V) nitrate was administered by gavage to groups of fed or fasted adult and 5-day-old rats. Some groups also received the oxidants quinhydrone or ferric iron, and others received the reducing agent ferrous iron. Adult mice received ferric or ferrous iron and 235Np. When the adult rats were killed at 7 days after gavage, measurements showed that, compared with rats that were fed, a 24-hr fast caused a fivefold increase in 237Np absorption and retention. Both quinhydrone and ferric iron caused an even greater increase in absorption in both fed and fasted rats. Ferrous iron, on the other hand, decreased absorption in fasted rats to values lower than those obtained in fed rats. Similar results were obtained in mice treated with 235Np and either ferric or ferrous iron. The highest absorption obtained after gavage of ferric iron to fasted rats and mice was about two orders of magnitude higher than the value obtained in animals that were fed before gavage. The effects of ferric and ferrous iron on neptunium absorption by neonatal rats were similar to their effects on adult animals but of lesser magnitude. These results are consistent with the hypothesis that Np(V), when given in small mass quantities to fed animals, is reduced in the gastrointestinal tract to Np(IV), which is less well absorbed than Np(V).

  4. Enhancement of the grafting performance and of the water absorption of cassava starch graft copolymer by gamma radiation

    NASA Astrophysics Data System (ADS)

    Kiatkamjornwong, Suda; Meechai, Nispa

    1997-06-01

    Enhancement of the gamma radiation grafting of acrylonitrile onto gelatinized cassava starch was investigated. Infrared spectrometry was used to follow the chemical changes in the grafting reaction and from saponification. The saponified starch- g-PAN (HSPAN) was then characterized in terms of grafting parameters to provide a guide for the optimum total dose (kGy) and the appropriate ratio of starch/acrylonitrile for a fixed dose rate of 2.5 × 10 -1 kGy/min. Other dose rates were also carried out to obtain the appropriate result of grafting copolymerization and of water absorption. A thin aluminium foil, covering the inner wall of the reaction vessel, was found to be far more effective than any other metal films in the enhancement of the grafting reaction and the water absorption as well. Nitric acid in the medium increases the grafting yield and the water absorption. Methyl ether hydroquinone inhibitor was evaluated for its ability to increase homopolymerization and decrease graft reaction. When styrene was used as a comonomer, it hampered the grafting of acrylonitrile onto starch backbone. The water absorption capacity was improved by freeze-drying the HSPAN. The treatment of the HSPAN with aluminium trichloride hexahydrate was found to enhance the degree of wicking, but to decrease the water absorbency.

  5. T₁ and T₂ dual-mode MRI contrast agent for enhancing accuracy by engineered nanomaterials.

    PubMed

    Shin, Tae-Hyun; Choi, Jin-sil; Yun, Seokhwan; Kim, Il-Sun; Song, Ho-Taek; Kim, Youngmee; Park, Kook In; Cheon, Jinwoo

    2014-04-22

    One of the holy grails in biomedical imaging technology is to achieve accurate imaging of biological targets. The development of sophisticated instrumentation and the use of contrast agents have improved the accuracy of biomedical imaging. However, the issue of false imaging remains a problem. Here, we developed a dual-mode artifact filtering nanoparticle imaging agent (AFIA) that comprises a combination of paramagnetic and superparamagnetic nanomaterials. This AFIA has the ability to perform "AND logic gate" algorithm to eliminate false errors (artifacts) from the raw images to enhance accuracy of the MRI. We confirm the artifact filtering capability of AFIA in MRI phantoms and further demonstrate that artifact-free imaging of stem cell migration is possible in vivo.

  6. Simultaneous ingestion of high-methoxy pectin from apple can enhance absorption of quercetin in human subjects.

    PubMed

    Nishijima, Tomohiko; Takida, Yoshiki; Saito, Yasuo; Ikeda, Takayuki; Iwai, Kunihisa

    2015-05-28

    Chronic ingestion of apple pectin has been shown to increase the absorption of quercetin in rats. The present study was designed to elucidate whether the simultaneous ingestion of quercetin with apple pectin could enhance the absorption of quercetin in humans, and the effects of dose dependency and degree of pectin methylation on quercetin absorption were also investigated. Healthy volunteers (n 19) received 200 ml of 0.5 mg/ml of quercetin drinks with or without 10 mg/ml of pectin each in a randomised cross-over design study with over 1-week intervals; urine samples from all the subjects were collected within 24 h after ingestion of the test drinks, and urinary deconjugated quercetin and its metabolites were determined using HPLC. The sum of urinary quercetin and its metabolites excreted was increased by 2.5-fold by the simultaneous ingestion of pectin. The metabolism of methylated quercetin (isorhamnetin and tamarixetin) was not affected by pectin ingestion. In six volunteers, who received quercetin drinks containing 0, 3 and 10 mg/ml of pectin, the sum of urinary quercetin and its metabolites excreted also increased in a pectin dose-dependent manner. Furthermore, the simultaneous ingestion of quercetin with low-methoxy and high-methoxy pectin, respectively, increased the sum of urinary excretion of quercetin and its metabolites by 1.69-fold and significantly by 2.13-fold compared with the ingestion of quercetin without pectin. These results elucidated that apple pectin immediately enhanced quercetin absorption in human subjects, and that its enhancing effect was dependent on the dose and degree of pectin methylation. The results also suggested that the viscosity of pectin may play a role in the enhancement of quercetin absorption.

  7. Infrared absorption spectroscopy and sensing of protein monolayers using high performance enhancing substrates and a mobile phone (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Dana, Aykutlu; Ayas, Sencer; Bakan, Gokhan; Ozgur, Erol; Guner, Hasan; Celebi, Kemal

    2016-09-01

    Infrared absorption spectroscopy has greatly benefited from the electromagnetic field enhancement offered by plasmonic surfaces. However, because of the localized nature of plasmonic fields, such field enhancements are limited to nm-scale volumes. Here, we demonstrate that a relatively small, but spatially-uniform field enhancement can yield a superior infrared detection performance compared to the plasmonic field enhancement exhibited by optimized infrared nanoantennas. A specifically designed CaF2/Al thin film surface is shown to enable observation of stronger vibrational signals from the probe material, with wider bandwidth and a deeper spatial extent of the field enhancement as compared to optimized plasmonic surfaces. It is demonstrated that the surface structure presented here can enable chemically specific and label-free detection of organic monolayers using surface enhanced infrared spectroscopy. Also, a low cost hand held infrared absorption measurement setup is demonstrated using a miniature bolometric sensor and a mobile phone. A specifically designed grating in combination with an IR light source yields an IR spectrometer covering 7-12 um range, with about 100 cm-1 resolution. Combining the enhancing substrates with the spectroscopy setup, low cost, high sensitivity mobile infrared sensing is enabled. The results have implications in homeland security and environmental monitoring as well as chemical analysis.

  8. Trait absorption is related to enhanced emotional picture processing and reduced processing of secondary acoustic probes.

    PubMed

    Benning, Stephen D; Rozalski, Vincent; Klingspon, Kara L

    2015-10-01

    Trait absorption reflects a propensity to have one's attention drawn to engaging sensory or imaginal experiences. It is related to self-reported levels of positive and negative emotionality, but little work has examined whether absorption is related to greater levels of basic emotional processing. We used the late positive potential (LPP) to pictures and P3 response to subsequent startle probes during those pictures to examine how absorption was related to initial emotional processing and reactivity to a second stimulus. Across genders, absorption was positively related to LPP amplitude to emotional versus neutral pictures at PZ, and it was negatively related to overall P3 amplitude to startle probes at FZ. Thus, absorption appears to index greater processing of emotional material at the cost of reduced processing of subsequent incoming stimuli.

  9. Enhanced Peroxide Resistance of In Vitro Mutagenized Fluorideresistant Klebsiella pneumoniae Ureases for Catalytic Buffering of Agent Decontamination Reactions

    DTIC Science & Technology

    2004-11-17

    1 ENHANCED PEROXIDE RESISTANCE OF IN VITRO MUTAGENIZED FLUORIDE- RESISTANT Klebsiella pneumoniae UREASES FOR CATALYTIC BUFFERING OF...oxidative surety agent decontamination technologies. Ammonia production from urea by urease neutralizes the production of O- alkylphosphonic acids...resulting from the hydrolysis of Nerve agents such as Sarin and VX. Fluoride production from Sarin hydrolysis inhibits native urease at low mM

  10. Development of a cavity enhanced absorption spectrometer for airborne measurements of CH4 and CO2

    NASA Astrophysics Data System (ADS)

    O'Shea, S. J.; Bauguitte, S. J.-B.; Gallagher, M. W.; Lowry, D.; Percival, C. J.

    2013-01-01

    High-resolution CH4 and CO2 measurements were made onboard the FAAM BAe 146 UK atmospheric research aircraft during a number of field campaigns. The system was based on an infrared spectrometer using the cavity enhanced absorption spectroscopy technique. Correction functions to convert the mole fractions retrieved from the spectroscopy to dry air mole fractions were derived using laboratory experiments and over a 3 month period showed good stability. Long-term performance of the system was monitored using WMO traceable calibration gases. During the first year of operation (29 flights) analysis of the system's in-flight calibrations suggest that its measurements are accurate to -0.07 ppbv (1 σ precision at 1 Hz = 2.48 ppbv) for CH4 and -0.06 ppmv (1 σ precision at 1 Hz = 0.66 ppmv) for CO2. The system was found to be very robust, no major motion or altitude dependency could be detected in the measurements. An inter-comparison between whole air samples that were analysed post-flight for CH4 and CO2 by cavity ring down spectroscopy showed a mean difference between the two techniques of -2.4 ppbv (1 σ = 2.3 ppbv) for CH4 and -0.22 ppmv (1 σ = 0.45 ppmv) for CO2. In September 2012, the system was used to sample biomass burning plumes in Brazil as part of the SAMBBA project (South American biomass burning analysis). From these and simultaneous CO measurements, emission factors for savannah fires were calculated. These were found to be 2.2 ± 0.2 g (kg dry matter)-1 for CH4 and 1710 ± 171 g (kg dry matter)-1 for CO2, which are in excellent agreement with previous estimates in the literature.

  11. Quantum-Confined and Enhanced Optical Absorption of Colloidal PbS Quantum Dots at Wavelengths with Expected Bulk Behavior.

    PubMed

    Debellis, Doriana; Gigli, Giuseppe; Ten Brinck, Stephanie; Infante, Ivan; Giansante, Carlo

    2017-02-08

    Nowadays it is well-accepted to attribute bulk-like optical absorption properties to colloidal PbS quantum dots (QDs) at wavelengths above 400 nm. This assumption permits to describe PbS QD light absorption by using bulk optical constants and to determine QD concentration in colloidal solutions from simple spectrophotometric measurements. Here we demonstrate that PbS QDs experience the quantum confinement regime across the entire near UV-vis-NIR spectral range, therefore also between 350 and 400 nm already proposed to be sufficiently far above the band gap to suppress quantum confinement. This effect is particularly relevant for small PbS QDs (with diameter of ≤4 nm) leading to absorption coefficients that largely differ from bulk values (up to ∼40% less). As a result of the broadband quantum confinement and of the high surface-to-volume ratio peculiar of nanocrystals, suitable surface chemical modification of PbS QDs is exploited to achieve a marked, size-dependent enhancement of the absorption coefficients compared to bulk values (up to ∼250%). We provide empirical relations to determine the absorption coefficients at 400 nm of as-synthesized and ligand-exchanged PbS QDs, accounting for the broadband quantum confinement and suggesting a heuristic approach to qualitatively predict the ligand effects on the optical absorption properties of PbS QDs. Our findings go beyond formalisms derived from Maxwell Garnett effective medium theory to describe QD optical properties and permit to spectrophotometrically calculate the concentration of PbS QD solutions avoiding underestimation due to deviations from the bulk. In perspective, we envisage the use of extended π-conjugated ligands bearing electronically active substituents to enhance light-harvesting in QD solids and suggest the inadequacy of the representation of ligands at the QD surface as mere electric dipoles.

  12. Enhancement of bioavailability of cinnarizine from its beta-cyclodextrin complex on oral administration with DL-phenylalanine as a competing agent.

    PubMed

    Tokumura, T; Nanba, M; Tsushima, Y; Tatsuishi, K; Kayano, M; Machida, Y; Nagai, T

    1986-04-01

    The present investigation is concerned with an improvement of the bioavailability of cinnarizine by administering its beta-cyclodextrin complex together with another compound which competes with the beta-cyclodextrin molecule in complex formation in aqueous solution (competing agent). The bioavailability of cinnarizine on oral administration of the cinnarizine-beta-cyclodextrin inclusion complex was enhanced by the simultaneous administration of DL-phenylalanine as a competing agent, e.g., the AUC was 1.9 and 2.7 times as large as those of the cinnarizine-beta-cyclodextrin complex alone and cinnarizine alone, respectively. The enhancement of AUC and Cmax completely depended on the dose of DL-phenylalanine. It was found from these results that DL-phenylalanine acted as a competing agent in the GI tract and the minimum effective dose required of DL-phenylalanine might be 1 g for 50 mg of cinnarizine in the cinnarizine-beta-cyclodextrin complex. Evaluating the competing effect of DL-phenylalanine in vitro using an absorption simulator, it was found that the decreased penetration rate of cinnarizine through the artificial lipid barrier with addition of beta-cyclodextrin was restored with the addition of DL-phenylalanine.

  13. Optimized dispersion of conductive agents for enhanced Li-storage performance of TiO2

    NASA Astrophysics Data System (ADS)

    Han, Moyan; Chen, Ge

    2016-12-01

    Novel TiO2/carbon (TiO2/C) composites have been synthesized by a layer-by-layer deposition method, with electrostatic interaction. The addition of carbon conductive agents enhances the electrochemical performance of TiO2. Carbon for these has been sourced 0D nitrogen-doped carbon, 1D carbon nanotubes and 2D graphene. The as-obtained TiO2/C composites show carbon nanotubes and titanium dioxide coaxial nanocables anchored on the graphene. The nitrogen-doped carbon is uniformly dispersed on the nanocables. As anode materials for Li-ion batteries, the TiO2/C composites exhibit excellent rate capability and cycling stability. A capacity of 150 mAh/g is retained at a current density of 4 A/g. The enhanced electrochemical performance may be attributed to the well-dispersed carbon conductive framework, which facilitates charge transfer during the lithium insertion/extraction process.

  14. Fast, low-noise, mode-by-mode, cavity-enhanced absorption spectroscopy by diode-laser self-locking

    NASA Astrophysics Data System (ADS)

    Morville, J.; Kassi, S.; Chenevier, M.; Romanini, D.

    2005-06-01

    A new technique of cavity enhanced absorption spectroscopy is described. Molecular absorption spectra are obtained by recording the transmission maxima of the successive TEMoo resonances of a high-finesse optical cavity when a Distributed Feedback Diode Laser is tuned across them. A noisy cavity output is usually observed in such a measurement since the resonances are spectrally narrower than the laser. We show that a folded (V-shaped) cavity can be used to obtain selective optical feedback from the intracavity field which builds up at resonance. This induces laser linewidth reduction and frequency locking. The linewidth narrowing eliminates the noisy cavity output, and allows measuring the maximum mode transmissions accurately. The frequency locking permits the laser to scan stepwise through the successive cavity modes. Frequency tuning is thus tightly optimized for cavity mode injection. Our setup for this technique of Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OF-CEAS) includes a 50 cm folded cavity with finesse ˜20 000 (ringdown time ˜20 μs) and allows recording spectra of up to 200 cavity modes (2 cm-1) using 100 ms laser scans. We obtain a noise equivalent absorption coefficient of ˜5×10-10 cm-1 for 1 s averaging over scans, with a dynamic range of four orders of magnitude.

  15. Polyvinylidene fluoride/siloxane nanofibrous membranes for long-term continuous CO2 -capture with large absorption-flux enhancement.

    PubMed

    Lin, Yi-Feng; Wang, Chi-Sen; Ko, Chia-Chieh; Chen, Chien-Hua; Chang, Kai-Shiun; Tung, Kuo-Lun; Lee, Kueir-Rarn

    2014-02-01

    In a CO2 membrane contactor system, CO2 passes through a hydrophobic porous membrane in the gas phase to contact the amine absorbent in the liquid phase. Consequently, additional CO2 gas is absorbed by amine absorbents. This study examines highly porous polyvinylidene fluoride (PVDF)/siloxane nanofibrous layers that are modified with hydrophobic fluoroalkylsilane (FAS) functional groups and successfully coated onto a macroporous Al2 O3 membrane. The performance of these materials in a membrane contactor system for CO2 absorption is also investigated. Compared with pristine PVDF nanofibrous membranes, the PVDF/siloxane nanofibrous membranes exhibit greater solvent resistance and mechanical strength, making them more suitable for use in CO2 capture by the membrane contactor. The PVDF/siloxane nanofibrous layer in highly porous FAS-modified membranes can prevent the wetting of the membrane by the amine absorbent; this extends the periods of continuous CO2 absorption and results in a high CO2 absorption flux with a minimum of 500 % enhancement over that of the uncoated membranes. This study suggests the potential use of an FAS-modified PVDF/siloxane nanofibrous membrane in a membrane contactor system for CO2 absorption. The resulting hydrophobic membrane contactor also demonstrates the potential for large-scale CO2 absorption during post-combustion processes in power plants.

  16. Comparison of experimental and modeled absorption enhancement by black carbon (BC) cored polydisperse aerosols under hygroscopic conditions.

    PubMed

    Shamjad, P M; Tripathi, S N; Aggarwal, S G; Mishra, S K; Joshi, Manish; Khan, Arshad; Sapra, B K; Ram, Kirpa

    2012-08-07

    The quantification of the radiative impacts of light absorbing ambient black carbon (BC) particles strongly depends on accurate measurements of BC mass concentration and absorption coefficient (β(abs)). In this study, an experiment has been conducted to quantify the influence of hygroscopic growth of ambient particles on light absorption. Using the hygroscopic growth factor (i.e., Zdanovskii-Stokes-Robinson (ZSR) approach), a model has been developed to predict the chemical composition of particles based on measurements, and the absorption and scattering coefficients are derived using a core-shell assumption with light extinction estimates based on Mie theory. The estimated optical properties agree within 7% for absorption coefficient and 30% for scattering coefficient with that of measured values. The enhancement of absorption is found to vary according to the thickness of the shell and BC mass, with a maximum of 2.3 for a shell thickness of 18 nm for the particles. The findings of this study underline the importance of considering aerosol-mixing states while calculating their radiative forcing.

  17. Balancing the stability and the catalytic specificities of OP hydrolases with enhanced V-agent activities.

    PubMed

    Reeves, T E; Wales, M E; Grimsley, J K; Li, P; Cerasoli, D M; Wild, J R

    2008-06-01

    Rational site-directed mutagenesis and biophysical analyses have been used to explore the thermodynamic stability and catalytic capabilities of organophosphorus hydrolase (OPH) and its genetically modified variants. There are clear trade-offs in the stability of modifications that enhance catalytic activities. For example, the H254R/H257L variant has higher turnover numbers for the chemical warfare agents VX (144 versus 14 s(-1) for the native enzyme (wild type) and VR (Russian VX, 465 versus 12 s(-1) for wild type). These increases are accompanied by a loss in stability in which the total Gibb's free energy for unfolding is 19.6 kcal/mol, which is 5.7 kcal/mol less than that of the wild-type enzyme. X-ray crystallographic studies support biophysical data that suggest amino acid residues near the active site contribute to the chemical and thermal stability through hydrophobic and cation-pi interactions. The cation-pi interactions appear to contribute an additional 7 kcal/mol to the overall global stability of the enzyme. Using rational design, it has been possible to make amino acid changes in this region that restored the stability, yet maintained effective V-agent activities, with turnover numbers of 68 and 36 s(-1) for VX and VR, respectively. This study describes the first rationally designed, stability/activity balance for an OPH enzyme with a legitimate V-agent activity, and its crystal structure.

  18. Methods for determining agent concentration profiles in agarose gel during convection-enhanced delivery.

    PubMed

    Sindhwani, Nikhil; Ivanchenko, Oleksandr; Lueshen, Eric; Prem, Komal; Linninger, Andreas A

    2011-03-01

    Convection-enhanced delivery (CED) is a promising technique to deliver large molecular weight drugs to the human brain for treatment of Parkinson's, Alzheimer's, or brain tumors. Researchers have used agarose gels to study mechanisms of agent transport in soft tissues like brain due to its similar mechanical and transport properties. However, inexpensive quantitative techniques to precisely measure achieved agent distribution in agarose gel phantoms during CED are missing. Such precise measurements of concentration distribution are needed to optimize drug delivery. An optical experimental method to accurately quantify agent concentration in agarose is presented. A novel geometry correction algorithm is used to determine real concentrations from observable light intensities captured by a digital camera. We demonstrate the technique in dye infusion experiments that provide cylindrical and spherical distributions when infusing with porous membrane and conventional single-port catheters, respectively. This optical method incorporates important parameters, such as optimum camera exposure, captured camera intensity calibration, and use of collimated light source for maximum precision. We compare experimental results with numerical solutions to the convection diffusion equation. The solutions of convection-diffusion equations in the cylindrical and spherical domains were found to match the experimental data obtained by geometry correction algorithm.

  19. [Enhanced phytoextraction of heavy metal contaminated soil by chelating agents and auxin indole-3-acetic acid].

    PubMed

    Zhou, Jian-min; Dang, Zhi; Chen, Neng-chang; Xu, Sheng-guang; Xie, Zhi-yi

    2007-09-01

    The environmental risk of chelating agents such as EDTA application to the heavy metals polluted soils and the stress on plant roots due to the abrupt increase metals concentration limit the wide commercial use of chelate-induced phytoextraction. Chelating agent ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) and auxin indole-3-acetic acid (IAA) were used for enhancing heavy metals uptake from soils by Zea mays L. (corn) in pot experiments. The metals content in plant tissues was quantified using an inductively coupled plasma mass spectrometer (ICP-MS). The results showed that the combination of IAA and EDTA increased the biomass by about 40.0% and the contents of Cu, Zn, Cd and Pb in corn shoots by 27.0%, 26.8%, 27.5% and 32.8% respectively, as compared to those in EDTA treatment. While NTA&IAA treatment increased the biomass by about 29.9% and the contents of Cu, Zn, Cd and Pb in corn shoots by 31.8%, 27.6%, 17.0% and 26.9% respectively, as compared to those in NTA treatment. These results indicated that corn growth was promoted, and the biomass and the accumulation of heavy metals in plant shoots were increased significantly with the addition of IAA, which probably helps to change the cell membrane properties and the biomass distribution, resulting in the alleviation of the phytotoxicity of metals and the chelating agents.

  20. Magnetic nanoparticles as gene delivery agents: enhanced transfection in the presence of oscillating magnet arrays

    NASA Astrophysics Data System (ADS)

    McBain, S. C.; Griesenbach, U.; Xenariou, S.; Keramane, A.; Batich, C. D.; Alton, E. W. F. W.; Dobson, J.

    2008-10-01

    Magnetic nanoparticle-based gene transfection has been shown to be effective in combination with both viral vectors and with non-viral agents. In these systems, therapeutic or reporter genes are attached to magnetic nanoparticles which are then focused to the target site/cells via high-field/high-gradient magnets. The technique has been shown to be efficient and rapid for in vitro transfection and compares well with cationic lipid-based reagents, producing good overall transfection levels with lower doses and shorter transfection times. In spite of its potential advantages (particularly for in vivo targeting), the overall transfection levels do not generally exceed those of other non-viral agents. In order to improve the overall transfection levels while maintaining the advantages inherent in this technique, we have developed a novel, oscillating magnet array system which adds lateral motion to the particle/gene complex in order to promote transfection. Experimental results indicate that the system significantly enhances overall in vitro transfection levels in human airway epithelial cells compared to both static field techniques (p<0.005) and the cationic lipids (p<0.001) tested. In addition, it has the previously demonstrated advantages of magnetofection—rapid transfection times and requiring lower levels of DNA than cationic lipid-based transfection agents. This method shows potential for non-viral gene delivery both in vitro and in vivo.

  1. Surface-enhanced Raman spectral analysis of blister agents and their hydrolysis products

    NASA Astrophysics Data System (ADS)

    Inscore, Frank; Farquharson, Stuart

    2006-10-01

    Protection of military personnel and civilians from water supplies poisoned by chemical warfare agents requires an analyzer that has sufficient sensitivity (μg/L), selectivity (differentiate the warfare agents from its hydrolysis products), and speed (less than 10 minutes) to be of value. In an effort to meet these requirements, we have been investigating the ability of surface-enhanced Raman spectroscopy (SERS) to detect these chemicals in water. The expected success of SERS is based on reported detection of single molecules, the one-to-one relationship between a chemical and its Raman spectrum, and the minimal sample preparation requirements. It is equally important to detect and distinguish the hydrolysis products of these agents to eliminate false-positive responses and evaluate the extent of an attack. Previously, we reported the SER spectra of GA, GB, VX and most of their hydrolysis products, as well as a preliminary study of HD, and its principle hydrolysis product thiodiglycol. Here we expand this study to include half-mustard, its hydrolysis product, 2-hydroxyethyl ethylsulfide, and ethyl ethylsulfide to better characterize the observed SER spectra. We also report the measurement of 10 μg/L of thiodiglycol as we continue to improve sensitivity.

  2. Size-dependent kinetic enhancement in hydrogen absorption and desorption of the Li-Mg-N-H system.

    PubMed

    Liu, Yongfeng; Zhong, Kai; Luo, Kun; Gao, Mingxia; Pan, Hongge; Wang, Qidong

    2009-02-11

    High operating temperature and slow kinetics retard the practical applications of the Li-Mg-N-H system for hydrogen storage. To alleviate these problems, a first attempt was carried out by synthesizing Li(2)MgN(2)H(2) through sintering a mixture of Mg(NH(2))(2)-2LiNH(2) and investigating its size-dependent hydrogen storage performance. A dramatically enhanced kinetics for hydrogen absorption/desorption was achieved with a reduction in the particle size. For the dehydrogenation reaction, a three-dimensional diffusion-controlled kinetic mechanism was identified for the first time by analyzing isothermal hydrogen desorption curves with a linear plot method. The experimental improvement and mechanistic understanding on the dehydrogenation kinetics of the Li-Mg-N-H system shed light on how to further decrease the operating temperature and enhance the hydrogen absorption/desorption rate of the amide/hydride combined materials.

  3. Chicken cathelicidin-2-derived peptides with enhanced immunomodulatory and antibacterial activities against biological warfare agents.

    PubMed

    Molhoek, E Margo; van Dijk, Albert; Veldhuizen, Edwin J A; Dijk-Knijnenburg, Helma; Mars-Groenendijk, Roos H; Boele, Linda C L; Kaman-van Zanten, Wendy E; Haagsman, Henk P; Bikker, Floris J

    2010-09-01

    Host defence peptides (HDPs) are considered to be excellent candidates for the development of novel therapeutic agents. Recently, it was demonstrated that the peptide C1-15, an N-terminal segment of chicken HDP cathelicidin-2, exhibits potent antibacterial activity while lacking cytotoxicity towards eukaryotic cells. In the present study, we report that C1-15 is active against bacteria such as Bacillus anthracis and Yersinia pestis that may potentially be used by bioterrorists. Substitution of single and multiple phenylalanine (Phe) residues to tryptophan (Trp) in C1-15 resulted in variants with improved antibacterial activity against B. anthracis and Y. pestis as well as decreased salt sensitivity. In addition, these peptides exhibited enhanced neutralisation of lipopolysaccharide (LPS)-induced release of pro-inflammatory cytokines in human peripheral blood mononuclear cells (PBMCs). The antibacterial and LPS-neutralising activities of these C1-15-derived peptides are exerted at concentrations far below the concentrations that are toxic to human PBMCs. Taken together, we show that Phe-->Trp substitutions in C1-15 variants enhances the antibacterial and LPS-neutralising activities against pathogenic bacteria, including those that may potentially be used as biological warfare agents.

  4. Enhanced mobility of fullerene (C60) nanoparticles in the presence of stabilizing agents.

    PubMed

    Wang, Yonggang; Li, Yusong; Costanza, Jed; Abriola, Linda M; Pennell, Kurt D

    2012-11-06

    Experimental and mathematical modeling studies were performed to examine the effects of stabilizing agents on the transport and retention of fullerene nanoparticles (nC(60)) in water-saturated quartz sand. Three stabilizing systems were considered: naturally occurring compounds known to stabilize nanoparticles (Suwannee river humic acid (SRHA) and fulvic acid (SRFA)), synthetic additives used to enhance nanoparticle stability (Tween 80, a nonionic surfactant), and residual contaminants resulting from the manufacturing process (tetrahydrofuran (THF)). The results of column experiments demonstrated that the presence of THF, at concentrations up to 44.5 mg/L, did not alter nC(60) transport and retention behavior, whereas addition of SRHA (20 mg C/L), SRFA (20 mg C/L), or Tween 80 (1000 mg/L) to the influent nC(60) suspensions dramatically increased the mobility of nC(60), as demonstrated by coincidental nanoparticle and nonreactive tracer effluent breakthrough curves (BTCs) and minimal nC(60) retention. When columns were preflushed with surfactant, nC(60) transport was significantly enhanced compared to that in the absence of a stabilizing agent. The presence of adsorbed Tween 80 resulted in nC(60) BTCs characterized by a declining plateau and retention profiles that exhibited hyperexponential decay. The observed nC(60) transport and retention behavior was accurately captured by a mathematical model that accounted for coupled surfactant adsorption-desorption dynamics, surfactant-nanoparticle interactions, and particle attachment kinetics.

  5. The MRI contrast agent gadoteridol enhances distribution of rAAV1 in the rat hippocampus.

    PubMed

    Hullinger, R; Ugalde, J; Purón-Sierra, L; Osting, S; Burger, C

    2013-12-01

    Contrast agents are commonly used in combination with magnetic resonance imaging (MRI) to monitor the distribution of molecules in the brain. Recent experiments conducted in our laboratory have shown that co-infusion of recombinant Adeno-associated virus serotype 5 (rAAV5) and the MRI contrast agent gadoteridol (Gd) enhances vector transduction in the rat striatum. The goal of this study was to determine whether gadoteridol may also be used as a tool to enhance transduction efficiency of rAAV1 and rAAV5 within the rat hippocampus. We show that Gd/rAAV1-GFP but not Gd/rAAV5-GFP co-infusion results in significantly higher distribution of the transgene both in the injected hemisphere as well as in the contralateral side and adjacent areas of cortex along the injection track. We also show that Gd/rAAV1-GFP co-infusion has no deleterious effect on hippocampal function as assessed by two tests of spatial memory formation. This work indicates that Gd can be exploited as a method to increase transduction efficiency of AAV1 in the hippocampus for animal studies.

  6. Anti-androgenic activity of absorption-enhanced 3, 3’-diindolylmethane in prostatectomy patients

    PubMed Central

    Hwang, Clara; Sethi, Seema; Heilbrun, Lance K; Gupta, Nilesh S; Chitale, Dhananjay A; Sakr, Wael A; Menon, Mani; Peabody, James O; Smith, Daryn W; Sarkar, Fazlul H; Heath, Elisabeth I

    2016-01-01

    Consumption of cruciferous vegetables is associated with a decreased risk of developing prostate cancer. Antineoplastic effects of cruciferous vegetables are attributable to bioactive indoles, most prominently, 3, 3’-diindolylmethane (DIM). In addition to effects on proliferation and apoptosis, DIM acts as an antiandrogen in prostate cancer cell lines. This study characterized the effects of prostatic DIM on the androgen receptor (AR) in patients with prostate cancer. Men with localized prostate cancer were treated with a specially formulated DIM capsule designed for enhanced bioavailability (BR-DIM) at a dose of 225 mg orally twice daily for a minimum of 14 days. DIM levels and AR activity were assessed at the time of prostatectomy. Out of 28 evaluable patients, 26 (93%) had detectable prostatic DIM levels, with a mean concentration of 14.2 ng/gm. The mean DIM plasma level on BR-DIM therapy was 9.0 ng/mL; levels were undetectable at baseline and in follow-up samples. AR localization in the prostate was assessed with immunohistochemistry. After BR-DIM therapy, 96% of patients exhibited exclusion of the AR from the cell nucleus. In contrast, in prostate biopsy samples obtained prior to BR-DIM therapy, no patient exhibited AR nuclear exclusion. Declines in PSA were observed in a majority of patients (71%). Compliance was excellent and toxicity was minimal. In summary, BR-DIM treatment resulted in reliable prostatic DIM levels and anti-androgenic biologic effects at well tolerated doses. These results support further investigation of BR-DIM as a chemopreventive and therapeutic agent in prostate cancer. PMID:27069550

  7. Inner salt-shaped small molecular photosensitizer with extremely enhanced two-photon absorption for mitochondrial-targeted photodynamic therapy.

    PubMed

    Hu, Wenbo; He, Tingchao; Jiang, Rongcui; Yin, Jun; Li, Lin; Lu, Xiaomei; Zhao, Hui; Zhang, Lei; Huang, Ling; Sun, Handong; Huang, Wei; Fan, Quli

    2017-02-04

    Herein, we experimentally and theoretically demonstrate an unprecedentedly enhanced two-photon absorption in a small organic molecule by a simple introduction of an inner salt-shaped structure. Moreover, such an inner salt-shaped small molecule also exhibits superior singlet oxygen quantum yield and fascinating structure-inherent mitochondrial-targeting ability for highly efficient two-photon photodynamic therapy via a mitochondrial apoptosis pathway.

  8. Tetrachloroethene degradation by reducing-agent enhanced Fe(II)/Fe(III) catalyzed percarbonate

    NASA Astrophysics Data System (ADS)

    Miao, Z.; Brusseau, M. L.; Lu, S.; Gu, X.; Yan, N.; Qiu, Z.; Sui, Q.

    2015-12-01

    This project investigated the effect of reducing agents on the degradation of tetrachloroethene(PCE) by Fe(II)/Fe(III) catalyzed sodium percarbonate (SPC). SPC possesses similar function as liquid H2O2, such that free H2O2 is released into solution when percarbonate is mixed with water. The addition of reducing agents, including hydroxylamine hydrochloride, sodium sulfite, ascorbic acid and sodium ascorbate, accelerated the Fe(III)/Fe(II) redoxcycle, leading to a relatively steady Fe(II) concentration and higher production of free radicals. This, in turn, resulted in enhanced PCE oxidation by SPC, with almost complete PCE removal obtained for appropriate Fe and SPC concentrations.The results of chemical probe tests, using nitrobenzene and carbon tetrachloride, demonstrated that HO● was the predominant radical in the system and that O2●-played a minor role. This was further confirmed by the results of electron paramagnetic resonance measurements and salicylic acid hydroxylationanalysis by high performance liquid chromatography(HPLC). PCE degradation decreased significantly with the addition of isopropanol, a strong HO● scavenger, supporting the hypothesis that HO● was primarily responsible for PCE degradation. It should be noted that the release of Cl- was slightly delayed in the first 20 mins, indicating that intermediate products were produced. However, gas chromatography mass spectrometry (GC/MS) analysis did not detect any chlorinated organic compound except PCE, indicating these intermediates were quickly degraded, which resulted in the complete conversion of PCE to CO2. In conclusion, the use of reducing agents to enhance Fe(II)/Fe(III) catalyzed SPC oxidation appears to be a promising approach for the rapid degradation of organic contaminants in groundwater.

  9. Comparison of aggregating agents for the surface-enhanced Raman analysis of benzodiazepines.

    PubMed

    Doctor, Erika L; McCord, Bruce

    2013-10-21

    Benzodiazepines are among the most prescribed compounds and are commonly present in many toxicological screens. They are also of concern forensically in cases of drug facilitated sexual assault. Currently these compounds are predominantly analyzed using immunoassay techniques; however more specific screening methods are needed. This paper demonstrates the applicability of surface enhanced Raman spectroscopy as a method for the analysis and detection of benzodiazepines. The procedure involves mixing urine extracts with gold nanoparticles and appropriate aggregating agents for trace detection of these compounds and their metabolites. In this paper we will discuss the optimization of various parameters of this technique as well as its application to screening urine samples. Eleven different benzodiazepines and metabolites were examined, including 1,2-triazolo-benzodiazepines and 1,4-benzodiazpines. Experiments were performed using four different chloride salts, MgCl2, CaCl2, KCl, and NaCl, as aggregating agents for the colloidal gold nanoparticles. Overall it was found that each aggregating agent produced different levels of signal enhancement for each drug. MgCl2 provided the lowest limit of detection at 2.5 ng mL(-1), and linearity over a wide range of concentrations for a variety of drugs chosen. It was also determined that the optimum MgCl2 concentration was 1.67 M. This method has shown the applicability of SERS for the detection of trace quantities of benzodiazepines in aqueous solutions as well as the optimization of the technique over a wide range of compounds. This technique can be utilized in the detection of trace benzodiazepines in toxicological samples following extraction of the analyte.

  10. Enhanced transdermal delivery of an anti-HIV agent via ethanolic liposomes.

    PubMed

    Dubey, Vaibhav; Mishra, Dinesh; Nahar, Manoj; Jain, Vikas; Jain, Narendra Kumar

    2010-08-01

    Indinavir, as a protease inhibitor with a short biological half life, variable pH-dependent oral absorption, and extensive first-pass metabolism, presents a challenge with respect to its oral administration. The current work aims to formulate and characterize indinavir-bearing ethanolic liposomes (ethosomes), and to investigate their enhanced transdermal delivery potential. The prepared ethanolic liposomes were characterized to be spherical, unilamellar structures having low polydispersity, nanometric size range, and improved entrapment efficiency over other delivery formulations. Permeation studies of indinavir across human cadaver skin resulted in enhanced transdermal flux from ethanolic liposomes that was significantly (P < 0.05) greater than that with ethanolic drug solution, conventional liposomes, or plain drug solution. Additionally, the ethanolic liposomes showed the shortest lag time for indinavir, thus presenting a suitable approach for transdermal delivery of this protease inhibitor. From the clinical editor: This study characterizes indinavir bearing ethanolic liposomes (ethosomes), and investigate their enhanced transdermal delivery potential, demonstrating a potentially a suitable approach for transdermal delivery of this protease inhibitor for HIV treatment, which typically has been associated with limited bioavailability via the oral route.

  11. Enhanced uptake of As, Zn, and Cu by Vetiveria zizanioides and Zea mays using chelating agents.

    PubMed

    Chiu, K K; Ye, Z H; Wong, M H

    2005-09-01

    Vetiveria zizaniodes (vetiver) is commonly known for its effectiveness in soil and sediment erosion control. It can tolerate to extreme soil conditions and produce a high biomass even growing in contaminated areas. Zea mays (maize) can also produce a very high biomass with a fast growth rate and possesses some degree of metal tolerance. A greenhouse study was conducted to investigate the feasibility of using vetiver and maize for remediation of arsenic (As)-, zinc (Zn-), and copper (Cu)-amended soils and evaluate the effects of chelating agents on metal uptake by these plants. Vetiver had a better growth (dry weight yield of root and shoot) than maize under different treatment conditions. The effects of different chelating agents on As, Zn, and Cu extraction from soil to soil solution were studied. Among the nine chelating agents used, it was noted that 20 mmol NTA could maximize As and Zn bioavailability, while 20 mmol HEIDA could maximize Cu bioavailability in the soil solution. The surge time in maximizing metal uptake ranged from 16 to 20 days which indicated that timing on plant harvest was an important factor in enhanced metal accumulation. In general, vetiver was a more suitable plant species than maize in terms of phytoextraction of metals from metal-contaminated soil. Application of NTA in As-amended soil and HEIDA in Cu-amended soil at the rate of 20 mmol kg(-1) increased 3-4-fold of As and Cu in shoot of both plants, whereas application of NTA (20 mmol kg(-1)) increased 37- and 1.5-fold of Zn accumulation in shoot of vetiver and maize, respectively. The potential environmental risk of metal mobility caused by chelating agents used for phytoextraction should not be overlooked.

  12. The effect of activated dimethicone and a proprietary antacid preparation containing this agent on the absorption of phenytoin.

    PubMed

    McElnay, J C; Uprichard, G; Collier, P S

    1982-04-01

    1 The bioavailabilty of phenytoin sodium (Epanutin both alone and in combination with activated dimethicone and Asilone (a proprietary antacid preparation containing activated dimethicone) was examined in six healthy male volunteers. 2 The bioavailability of phenytoin when given concomitantly with Asilone was decreased in five of six volunteer subjects (by greater than 30% in three subjects) although this decrease was not shown to be statistically significant. 3 Dimethicone, which has been shown to decrease phenytoin absorption in vitro did not affect phenytoin bioavailability in vivo. 4 It is recommended that when treating patients stabilised on phenytoin one should exercise caution with concomitant phenytoin and antacid therapy to guard against possible changed drug absorption.

  13. Enabling forbidden processes: quantum and solvation enhancement of nitrate anion UV absorption.

    PubMed

    Svoboda, Ondřej; Kubelová, Lucie; Slavíček, Petr

    2013-12-05

    We present simulated electronic absorption spectra of isolated and solvated nitrate anion in the UV region, focusing primarily on the absorption into the first absorption band around 300 nm. This weak absorption band in this spectral region is responsible for the generation of NOx in the polar areas or OH(•) radicals in the hydrosphere. The 300 nm absorption band is symmetrically strongly forbidden and coupling of at least two vibrational modes is needed to allow the transition in the isolated nitrate anion. Further symmetry breaking is provided by solvation. In this study we model the absorption spectra of nitrate-water clusters using the combined reflection principle path integral molecular dynamics (RP-PIMD) method. Condensed phase UV spectra are modeled within a cluster-continuum model. The calculated spectra are compared with experimental bulk phase measurements and reasonable agreement is found. We also provide a benchmarking of the DFT functionals to be used for a description of the electronically excited states of solvated nitrate anion.

  14. Sandwich concept: enhancement for direct absorption measurements by laser-induced deflection (LID) technique

    NASA Astrophysics Data System (ADS)

    Mühlig, Ch.; Bublitz, S.; Paa, W.

    2012-11-01

    The new sandwich concept for absolute photo-thermal absorption measurements using the laser induced deflection (LID) technique is introduced and tested in comparison to the standard LID concept. The sandwich concept's idea is the decoupling of the optical materials for the pump and probe beams by placing a sample of investigation in between two optical (sandwich) plates. The pump beam is guided through the sample whereas the probe beams are deflected within the sandwich plates by the thermal lens that is generated by heat transfer from the irradiated sample. Electrical simulation and laser experiments reveal that using appropriate optical materials for the sandwich plates, the absorption detection limit for photo-thermally insensitive materials can be lowered by up to two orders of magnitude. Another advantage of the sandwich concept, the shrinking of the currently required minimum sample size, was used to investigate the laser induced absorption change in a Nd:YVO4 crystal at 1030nm. It was found that the absorption in Nd:YVO4 lowers due to the laser irradiation but partially recovers during irradiation breaks. Furthermore, absorption spectroscopy has been performed at two LBO crystals in the wavelength range 410...600nm to study the absorption structure around the SHG wavelengths of common high power lasers based on Neodymium doped laser crystals.

  15. Enhanced photoluminescence due to two-photon enhanced three-photon absorption in Mn{sup 2+}-doped ZnS quantum dots

    SciTech Connect

    Subha, Radhu; Nalla, Venkatram; Ji, Wei; Feng, Xiaobo; Vijayan, C.

    2014-10-15

    In this work, we have investigated the multi-photon absorption induced photoluminescence in Mn{sup 2+}-doped ZnS quantum dots in the wavelength range 860 – 1050 nm (Near-Infrared Window I). The observed three-photon action cross-section has been compared with the theoretical prediction under four band approximation. An enhancement of four to five orders has been observed in the range from 970 to 1050 nm compared to the theoretical value, which is attributed to two-photon enhanced three-photon absorption. Transient lifetime measurements reveal a lifetime of 0.35 ± 0.3 ms, which is four to five orders higher than other conventional fluorescent probes.

  16. Transdermal absorption of the herbicide 2,4-dichlorophenoxyacetic acid is enhanced by both ethanol consumption and sunscreen application.

    PubMed

    Brand, R M; McMahon, L; Jendrzejewski, J L; Charron, A R

    2007-01-01

    Xenobiotics absorption is a health concern and skin is a major exposure site for many of these chemicals. Both alcohol consumption and topical sunscreen application act as transdermal penetration enhancers for model xenobiotics. The effect of combining these two treatments on transdermal absorption of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was therefore examined. Skin from rats ingesting low (1.5 g/kg) medium (4.3 g/kg) or high (6 g/kg) ethanol doses or saline control was treated with a commercially available sunscreen containing titanium dioxide and octyl methoxycinnimate and transdermal absorption of 2,4-D was monitored. Ethanol increased penetration by a factor of 1.9, 2.0 and 2.5 for animals treated with 1.5, 4.3 and 6 g/kg respectively, demonstrating an ethanol-induced dose response. Sunscreen application to skin from ethanol gavaged rats caused 2,4-D absorption above that induced by ethanol alone by an additional factor of 1.3, 2.1 and 2.9 for 1.5, 4.3 and 6 g/kg respectively. Comparing 2,4-D transdermal absorption after exposure to both ethanol and sunscreen with a theoretical value (sum of penetration after ethanol or sunscreen treatment) demonstrates that these two treatments enhance additively at the higher doses tested. Results of this study emphasize the importance of limiting excessive alcohol consumption in individuals with potential herbicide exposure rather than discouraging the use of sunscreens, since the consequences of UV-induced skin cancer are far more series than the risks that would be associated with observed increases in chemical exposure.

  17. Modeling the kinetics of digoxin absorption: enhancement by P-glycoprotein inhibition.

    PubMed

    Weiss, Michael; Sermsappasuk, Pakawadee; Siegmund, Werner

    2012-03-01

    An increase in the area under the curve (AUC) after oral digoxin due to coadministration of drugs known as P-glycoprotein (P-gp) inhibitors has been reported in several studies, but there is very little information on the rate of absorption after P-gp inhibition. Based on an inverse Gaussian density absorption model and using a population approach, the authors reanalyzed data showing an increase in oral digoxin AUC in healthy volunteers after coadministration of talinolol. The model fitted the data well, and the results revealed that the maximum rate of digoxin absorption increased nearly 2-fold, whereas bioavailability increased only by 21%. It is concluded that the increase in the rate of absorption seems to be a better indicator of intestinal P-gp inhibition than the increase in extent of absorption. Furthermore, the authors use a simulation study to demonstrate the ability of the method to estimate bioavailability based on the population characteristics of digoxin disposition kinetics obtained from a different group of healthy volunteers.

  18. Alginate enhances excretion and reduces absorption of strontium and cesium in rats.

    PubMed

    Idota, Yoko; Harada, Hitomi; Tomono, Takumi; Morimoto, Kaori; Kobayashi, Shoko; Kakinuma, Chihaya; Miyajima, Chihiro; Kasahara, Fumiyoshi; Ogihara, Takuo

    2013-01-01

    Alginate (ALA), which is an intercellular polysaccharide associated with brown algae, is used as a food additive, a health food and a medicine. Here, we first examined the adsorption of strontium (Sr) and cesium (Cs) by ALA in vitro, and then evaluated the effects of ALA on absorption and excretion of Sr and Cs in rats, in order to evaluate its potential usefulness for minimizing radiation damage from materials released after a nuclear accident. Both Sr and Cs were concentration-dependently adsorbed by sodium alginate (ALA-Na) in vitro. In rats given diet containing either ALA-Na or calcium alginate (ALA-Ca) for two weeks, the plasma concentration of Sr gradually decreased compared with the controls (normal diet); however, in the case of Cs, the plasma concentration was decreased only in the ALA-Ca group, but not the ALA-Na group. Moreover, we examined the effect of preadministration of diet containing either ALA-Na or ALA-Ca on absorption of Sr and Cs administered orally as the chloride salts to rats. Absorption of both Sr and Cs was reduced in the ALA-Ca group, while absorption of only Sr was reduced in the ALA-Na group. Safety assessments indicated that ALA-Ca is safer than ALA-Na. These results indicate that ALA-Ca reduces absorption and promotes excretion of both Sr and Cs, while ALA-Na does so only for Sr.

  19. Hierarchical porous Ni@boehmite/nickel aluminum oxide flakes with enhanced microwave absorption ability.

    PubMed

    Zhao, Biao; Liu, Junwei; Guo, Xiaoqin; Zhao, Wanyu; Liang, Luyang; Ma, Chao; Zhang, Rui

    2017-03-29

    In this article, composites consisting of porous Ni cores coated with boehmite/nickel aluminum oxide nanoflakes were successfully prepared by a versatile method. The crystal constituents and shapes of the boehmite/nickel aluminum oxide nanoflakes were strongly influenced by reaction temperature, and their microwave absorption properties were investigated in terms of complex permittivity and permeability. The results reveal that the composites comprising porous Ni cores coated with boehmite/nickel aluminum oxide synthesized at 180 °C present superior absorption properties. The optimal reflection loss is -44.3 dB (>99.99% attenuation) at 14.4 GHz, and the effective absorption (below -10 dB) bandwidth can be monitored in the frequency range of 5.8-18.0 GHz for an absorber with thickness in the range of 1.5-3.5 mm. The high dissipation capability, good impedance match and multiple reflection of the porous flaky structure are responsible for the improvement in microwave absorption. Moreover, a new absorption mechanism was proposed for the porous structure. In this mechanism, the porous structure serves as a spreading container, which attenuates electromagnetic energy by prolonging the travel path and constrains waves in the void space to gradually consume energy. This method paves a new avenue to design porous magnetic-dielectric absorbing materials.

  20. Enhancing sound absorption and transmission through flexible multi-layer micro-perforated structures.

    PubMed

    Bravo, Teresa; Maury, Cédric; Pinhède, Cédric

    2013-11-01

    Theoretical and experimental results are presented into the sound absorption and transmission properties of multi-layer structures made up of thin micro-perforated panels (ML-MPPs). The objective is to improve both the absorption and insulation performances of ML-MPPs through impedance boundary optimization. A fully coupled modal formulation is introduced that predicts the effect of the structural resonances onto the normal incidence absorption coefficient and transmission loss of ML-MPPs. This model is assessed against standing wave tube measurements and simulations based on impedance translation method for two double-layer MPP configurations of relevance in building acoustics and aeronautics. Optimal impedance relationships are proposed that ensure simultaneous maximization of both the absorption and the transmission loss under normal incidence. Exhaustive optimization of the double-layer MPPs is performed to assess the absorption and/or transmission performances with respect to the impedance criterion. It is investigated how the panel volumetric resonances modify the excess dissipation that can be achieved from non-modal optimization of ML-MPPs.

  1. Enhanced nucleotide excision repair capacity in lung cancer cells by preconditioning with DNA-damaging agents.

    PubMed

    Choi, Ji Ye; Park, Jeong-Min; Yi, Joo Mi; Leem, Sun-Hee; Kang, Tae-Hong

    2015-09-08

    The capacity of tumor cells for nucleotide excision repair (NER) is a major determinant of the efficacy of and resistance to DNA-damaging chemotherapeutics, such as cisplatin. Here, we demonstrate that using lesion-specific monoclonal antibodies, NER capacity is enhanced in human lung cancer cells after preconditioning with DNA-damaging agents. Preconditioning of cells with a nonlethal dose of UV radiation facilitated the kinetics of subsequent cisplatin repair and vice versa. Dual-incision assay confirmed that the enhanced NER capacity was sustained for 2 days. Checkpoint activation by ATR kinase and expression of NER factors were not altered significantly by the preconditioning, whereas association of XPA, the rate-limiting factor in NER, with chromatin was accelerated. In preconditioned cells, SIRT1 expression was increased, and this resulted in a decrease in acetylated XPA. Inhibition of SIRT1 abrogated the preconditioning-induced predominant XPA binding to DNA lesions. Taking these data together, we conclude that upregulated NER capacity in preconditioned lung cancer cells is caused partly by an increased level of SIRT1, which modulates XPA sensitivity to DNA damage. This study provides some insights into the molecular mechanism of chemoresistance through acquisition of enhanced DNA repair capacity in cancer cells.

  2. Reduction in cholesterol absorption is enhanced by stearate-enriched plant sterol esters in hamsters.

    PubMed

    Rasmussen, Heather E; Guderian, David M; Wray, Curtis A; Dussault, Patrick H; Schlegel, Vicki L; Carr, Timothy P

    2006-11-01

    Consumption of plant sterol esters reduces plasma LDL cholesterol concentration by inhibiting intestinal cholesterol absorption. Commercially available plant sterol esters are prepared by esterifying free sterols to fatty acids from edible plant oils such as canola, soybean, and sunflower. To determine the influence of the fatty acid moiety on cholesterol metabolism, plant sterol esters were made with fatty acids from soybean oil (SO), beef tallow (BT), or purified stearic acid (SA) and fed to male hamsters for 4 wk. A control group fed no plant sterol esters was also included. Hamsters fed BT and SA had significantly lower cholesterol absorption and decreased concentrations of plasma non-HDL cholesterol and liver esterified cholesterol, and significantly greater fecal sterol excretion than SO and control hamsters. Cholesterol absorption was lowest in hamsters fed SA (7.5%), whereas it was 72.9% in control hamsters. Cholesterol absorption was correlated with fecal sterol excretion (r = -0.72, P < 0.001), liver cholesterol concentration (r = 0.88, P < 0.001), and plasma non-HDL cholesterol concentration (r = 0.85, P < 0.001). A multiple regression model that included each sterol ester type vs. cholesterol absorption indicated that intake of steryl stearate was the only dietary component that contributed significantly to the model (R2 = -0.75, P < 0.001). Therefore, our results demonstrate that BT and SA are more effective than SO in reducing cholesterol absorption, liver cholesterol, and plasma non-HDL cholesterol concentration, suggesting that cardioprotective benefits can be achieved by consuming stearate-enriched plant sterol esters.

  3. Enhanced light absorption in thin film silicon solar cells with Fourier-series based periodic nanostructures.

    PubMed

    Guo, Xiaowei; Wang, Dashuai; Liu, Bang; Li, Shaorong; Sheng, Xing

    2016-01-25

    We proposed a Fourier-series based periodic nanostructure(FSPN) for light trapping in thin film silicon solar cells. By globally optimizing the Fourier coefficients across entire silicon absorption spectrum, we obtained a FSPN structure with short circuit current density greater than 24 mA/cm(2) for a 1μm real silicon absorption layer. The spectral analysis shows at normal incidence the FSPN exhibits a collection effect of periodic gratings and performs over 84.6% better than random texture. The angular analysis shows that the FSPN outperforms grating and random textures within 70 °.

  4. Enhanced Heat Transfer Tubes for Absorber of Absorption Chiller/Heater

    NASA Astrophysics Data System (ADS)

    Furukawa, Masahiro; Sasaki, Naoe; Kaneko, Toshiyuki; Nosetani, Tadashi

    For the purpose of development of high performance absorption chiller/heater utilizing lithium bromide aqueous solution as working fluid, it is the most effective to improve the performance of absorber with the largest heat transfer area of the four heat exchangers. This paper introduces two kinds of double fluted tubes for the absorber of absorption chiller/heater. Arm tube and floral tube have about 40% higter heat transfer performance than the plain tube conventionally used in absorber. The former is manufactured by double drawbench process, while the latter by single drawbench process. Therefore, floral tube is expected to realize both high heat transfer perfoemance and low cost.

  5. Large integrated absorption enhancement in plasmonic solar cells by combining metallic gratings and antireflection coatings.

    PubMed

    Munday, Jeremy N; Atwater, Harry A

    2011-06-08

    We describe an ultrathin solar cell architecture that combines the benefits of both plasmonic photovoltaics and traditional antireflection coatings. Spatially resolved electron generation rates are used to determine the total integrated current improvement under AM1.5G solar illumination, which can reach a factor of 1.8. The frequency-dependent absorption is found to strongly correlate with the occupation of optical modes within the structure, and the improved absorption is mainly attributed to improved coupling to guided modes rather than localized resonant modes.

  6. Development of a Near-Ir Cavity Enhanced Absorption Spectrometer for the Detection of Atmospheric Oxidation Products and Organoamines

    NASA Astrophysics Data System (ADS)

    Eddingsaas, Nathan C.; Jewell, Breanna; Thurnherr, Emily

    2014-06-01

    An estimated 10,000 to 100,000 different compounds have been measured in the atmosphere, each one undergoes many oxidation reactions that may or may not degrade air quality. To date, the fate of even some of the most abundant hydrocarbons in the atmosphere is poorly understood. One difficulty is the detection of atmospheric oxidation products that are very labile and decompose during analysis. To study labile species under atmospheric conditions, a highly sensitive, non-destructive technique is needed. Here we describe a near-IR incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) setup that we are developing to meet this end. We have chosen to utilize the near-IR, where vibrational overtone absorptions are observed, due to the clean spectral windows and better spectral separation of absorption features. In one spectral window we can simultaneously and continuously monitor the composition of alcohols, hydroperoxides, and carboxylic acids in an air mass. In addition, we have used our CEAS setup to detect organoamines. The long effective path length of CEAS allows for low detection limits, even of the overtone absorption features, at ppb and ppt levels.

  7. Enhanced photosensitivity of InGaZnO-TFT with a CuPc light absorption layer

    NASA Astrophysics Data System (ADS)

    Li, Jun; Zhou, Fan; Lin, Hua-Ping; Zhu, Wen-Qing; Zhang, Jian-Hua; Jiang, Xue-Yin; Zhang, Zhi-Lin

    2012-04-01

    A copper phthalocyanine (CuPc) organic semiconductor is capped onto an amorphous indium-gallium-zinc-oxide (InGaZnO) thin film transistor (TFT) to enhance the photosensitivity of InGaZnO-TFT. The CuPc organic semiconductor is served as a light absorption layer and forms a p-n junction with the InGaZnO film. After 60 s white light illumination, light responsivity (R) of InGaZnO-TFT with a CuPc light absorption layer reaches a value of 148.5 A/W at a gate-source voltage (VGS) of 20 V, which is much larger than that (31.2 A/W) of the conventional InGaZnO-TFT. The results are attributed to the following mechanism. First, a CuPc layer is employed as the light absorption layer. Second, CuPc/InGaZnO p-n junction enables the injection of electron into InGaZnO film. Our results indicate that using CuPc as light absorption layer is an effective approach to improve the photosensitivity of InGaZnO-TFT.

  8. Efficient Vacuum-Deposited Ternary Organic Solar Cells with Broad Absorption, Energy Transfer, and Enhanced Hole Mobility.

    PubMed

    Shim, Hyun-Sub; Moon, Chang-Ki; Kim, Jihun; Wang, Chun-Kai; Sim, Bomi; Lin, Francis; Wong, Ken-Tsung; Seo, Yongsok; Kim, Jang-Joo

    2016-01-20

    The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for visible absorption and 2-((7-(5-(dip-tolylamino)thiophen-2-yl)benzo[c]-[1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCTB) for near-infrared absorption, codeposited with C70 in the ternary layer. The ternary device achieved a power conversion efficiency of 8.02%, which is 23% higher than that of binary OPVs. This enhancement is the result of incorporating two donors with complementary absorption covering wavelengths of 350 to 900 nm with higher hole mobility in the ternary layer than that of binary layers consisting of one donor and C70, combined with energy transfer from the donor with lower hole mobility (DTTz) to that with higher mobility (DTDCTB). This structure fulfills all the requirements for efficient ternary OPVs.

  9. Large-scale enhancement in aerosol absorption in the lower free troposphere over continental India during spring

    NASA Astrophysics Data System (ADS)

    Nair, Vijayakumar S.; Babu, S. Suresh; Gogoi, Mukunda M.; Moorthy, K. Krishna

    2016-11-01

    Aerosol absorption in the lower troposphere over continental India was assessed using extensive measurements of the vertical distribution of absorption coefficients aboard an instrumented aircraft. Measurements were made from seven base stations during winter (November-December 2012) and spring (April-May 2013), supplemented by the data from the networks of surface observatories. A definite enhancement in aerosol absorption has been observed in the lower free troposphere over the Indo-Gangetic Plain (IGP) during spring, along with a reduction near the surface. The regional mean aerosol absorption optical depth (AAOD) over IGP, which was derived from aircraft observations (integrated from the ground to 3 km), increased from 0.020 ± 0.009 in winter to 0.048 ± 0.01 in spring. The columnar AAOD depicted weak and distinctly different seasonal variations than that of surface level black carbon mass concentrations. This contrasting difference in the seasonality indicates the presence of elevated layers of absorbing aerosols during spring in association with the long-range transport and vertical convective lofting of aerosols.

  10. Oral delivery system for two-pulse colonic release of protein drugs and protease inhibitor/absorption enhancer compounds.

    PubMed

    Del Curto, Maria Dorly; Maroni, Alessandra; Palugan, Luca; Zema, Lucia; Gazzaniga, Andrea; Sangalli, Maria Edvige

    2011-08-01

    It is well known that the intestinal stability and absorption of protein drugs are improved when enzyme inhibitors/permeation enhancers are coadministered. Recently, it was hypothesized that an increased effectiveness of these adjuvants might be achieved by timing their release prior to that of the protein, so that a more favorable environment would be established in advance. Therefore, an oral system was proposed for two-pulse colonic release of insulin and the protease inhibitor camostat mesilate/absorption enhancer sodium glycocholate. The device consisted of a drug-containing core, an inner swellable/erodible low-viscosity hydroxypropyl methylcellulose (HPMC) coating, an intermediate adjuvant layer, and an additional outer HPMC coating. HPMC coats and camostat mesilate/sodium glycocholate films with differing thicknesses were applied to immediate-release tablet cores by aqueous spray coating. The obtained units were characterized for weight, thickness, breaking force, and release performance. All systems showed satisfactory technological properties and the pursued pulsatile delivery behavior, with programmable delay phases preceding inhibitor/enhancer release and elapsing between inhibitor/enhancer and protein release, respectively. Indeed, both lag times linearly correlated with the relevant HPMC coating level. The system was thus proven suitable for yielding two-pulse release profiles, in which lag phases could be modulated to provide convenient concentration patterns for proteins and adjuvants.

  11. Effects of skin preapplication treatments and postapplication cleansing agents on dermal absorption of 2,4-dichlorophenoxyacetic acid dimethylamine by Fischer 344 rats.

    PubMed

    Pelletier, O; Ritter, L; Caron, J

    1990-12-01

    Various methods of preparing dermal application sites in Fischer 344 rats prior to exposure to 2,4-dichlorophenoxyacetic acid dimethylamine salt (2,4-D amine) and the effect of various cleansing agents following exposure were examined by measuring recoveries of 14C-labeled 2,4-D amine in skin, postapplication cleansing solution, blood, and urine. The middorsal area of the rat was the site of application for four treatments tested: (1) hair clipping only, (2) hair clipping followed by an epilatory cream, (3) hair clipping plus shaving with an electrical razor, and (4) as in treatment 3 followed by washing with soap and water. A last preparation was the rat's tail thoroughly brushed with soap and water. The results indicated that the tail retained greater than 75% of the material, thus preventing its absorption into the blood stream and subsequent removal by cleansing. With treatment 1 the dense short hair remaining after clipping impaired the absorption of 2,4-D as evidenced by considerably lower blood and urinary levels than treatments 2-4. With preparations 1-4, 45-61% of the dose was removed with the 7-h postapplication cleansing and a further 5-6% with the subsequent 23-h cleansing. In other studies using preparation 3 above, the following cleansing agents were tested: soap and water, water, isopropanol, acetone, and Rad-Con, a foam-producing cleanser. Rad-Con removed more 2,4-D from the skin than other cleansing agents after 7 h of exposure and more than soap and water after 23 h. The percentages of 2,4-D left on the skin following either 7- or 23-h cleansing with Rad-Con were 8-12%, nearly half those following the other cleansing agents. Cleansing agents other than Rad-Con presented little advantage over soap and water. With all cleansing agents, delaying cleansing from 7 to 23 h after exposure resulted in higher blood and urinary levels of 2,4-D measured 24 h after application.

  12. Plasmonically enhanced metal–insulator multistacked photodetectors with separate absorption and collection junctions for near-infrared applications

    PubMed Central

    Abedini Dereshgi, Sina; Sisman, Zulkarneyn; Topalli, Kagan; Okyay, Ali Kemal

    2017-01-01

    Plasmonically enhanced metal-insulator-metal (MIM) type structures are popular among perfect absorbers and photodetectors in which the field enhancement (for increased absorption) mechanism is directly coupled with collection (photocurrent) processes. In this work we propose a device structure that decouples absorption and collection parts for independent optimization. Double-stacked MIM (i.e. MIMIM) photodetectors operating in the near-infrared (NIR) spectrum up to 1200 nm wavelength are demonstrated. In the absorbing MIM (at the top side), we have used Silver nanoparticles resulting from dewetting, yielding a very low reflection of 10% for the most part of the 400 to 1000 nm wavelength range. An unconventional plasmonic material, Chromium, exhibits an absorption peak of over 80% at 1000 nm. The complete device has been fabricated and the photo-collection tunneling MIM (at the bottom) suppresses the leakage current by metal workfunction difference. An optimized stack consisting of Silver – Hafnium Oxide – Chromium – Aluminum Oxide – Silver nanoparticles (from bottom to top) yields a dark current of 7 nA and a photoresponsivity peak of 0.962 mA/W at 1000 nm and a full width at half maximum of 300 nm, while applied bias is 50 mV and device areas are 300 μm × 600 μm. PMID:28181590

  13. Plasmonically enhanced metal–insulator multistacked photodetectors with separate absorption and collection junctions for near-infrared applications

    NASA Astrophysics Data System (ADS)

    Abedini Dereshgi, Sina; Sisman, Zulkarneyn; Topalli, Kagan; Okyay, Ali Kemal

    2017-02-01

    Plasmonically enhanced metal-insulator-metal (MIM) type structures are popular among perfect absorbers and photodetectors in which the field enhancement (for increased absorption) mechanism is directly coupled with collection (photocurrent) processes. In this work we propose a device structure that decouples absorption and collection parts for independent optimization. Double-stacked MIM (i.e. MIMIM) photodetectors operating in the near-infrared (NIR) spectrum up to 1200 nm wavelength are demonstrated. In the absorbing MIM (at the top side), we have used Silver nanoparticles resulting from dewetting, yielding a very low reflection of 10% for the most part of the 400 to 1000 nm wavelength range. An unconventional plasmonic material, Chromium, exhibits an absorption peak of over 80% at 1000 nm. The complete device has been fabricated and the photo-collection tunneling MIM (at the bottom) suppresses the leakage current by metal workfunction difference. An optimized stack consisting of Silver – Hafnium Oxide – Chromium – Aluminum Oxide – Silver nanoparticles (from bottom to top) yields a dark current of 7 nA and a photoresponsivity peak of 0.962 mA/W at 1000 nm and a full width at half maximum of 300 nm, while applied bias is 50 mV and device areas are 300 μm × 600 μm.

  14. Surface-modified solid lipid nanoparticles for oral delivery of docetaxel: enhanced intestinal absorption and lymphatic uptake

    PubMed Central

    Cho, Hyun-Jong; Park, Jin Woo; Yoon, In-Soo; Kim, Dae-Duk

    2014-01-01

    Docetaxel is a potent anticancer drug, but development of an oral formulation has been hindered mainly due to its poor oral bioavailability. In this study, solid lipid nanoparticles (SLNs) surface-modified by Tween 80 or D-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS 1000) were prepared and evaluated in terms of their feasibility as oral delivery systems for docetaxel. Tween 80-emulsified and TPGS 1000-emulsified tristearin-based lipidic nanoparticles were prepared by a solvent-diffusion method, and their particle size distribution, zeta potential, drug loading, and particle morphology were characterized. An in vitro release study showed a sustained-release profile of docetaxel from the SLNs compared with an intravenous docetaxel formulation (Taxotere®). Tween 80-emulsified SLNs showed enhanced intestinal absorption, lymphatic uptake, and relative oral bioavailability of docetaxel compared with Taxotere in rats. These results may be attributable to the absorption-enhancing effects of the tristearin nanoparticle. Moreover, compared with Tween 80-emulsified SLNs, the intestinal absorption and relative oral bioavailability of docetaxel in rats were further improved in TPGS 1000-emulsified SLNs, probably due to better inhibition of drug efflux by TPGS 1000, along with intestinal lymphatic uptake. Taken together, it is worth noting that these surface-modified SLNs may serve as efficient oral delivery systems for docetaxel. PMID:24531717

  15. Ultrafast Charge Transfer and Enhanced Absorption in MoS2-Organic van der Waals Heterojunctions Using Plasmonic Metasurfaces.

    PubMed

    Petoukhoff, Christopher E; Krishna, M Bala Murali; Voiry, Damien; Bozkurt, Ibrahim; Deckoff-Jones, Skylar; Chhowalla, Manish; O'Carroll, Deirdre M; Dani, Keshav M

    2016-11-22

    Hybrid organic-inorganic heterostructures are attracting tremendous attention for optoelectronic applications due to their low-cost processing and high performance in devices. In particular, van der Waals p-n heterojunctions formed between inorganic two-dimensional (2D) materials and organic semiconductors are of interest due to the quantum confinement effects of 2D materials and the synthetic control of the physical properties of organic semiconductors, enabling a high degree of tunable optoelectronic properties for the heterostructure. However, for photovoltaic applications, hybrid 2D-organic heterojunctions have demonstrated low power conversion efficiencies due to the limited absorption from constraints on the physical thickness of each layer. Here, we investigate the ultrafast charge transfer dynamics between an organic polymer:fullerene blend and 2D n-type MoS2 using transient pump-probe reflectometry. We employ plasmonic metasurfaces to enhance the absorption and charge photogeneration within the physically thin hybrid MoS2-organic heterojunction. For the hybrid MoS2-organic heterojunction in the presence of the plasmonic metasurface, the charge generation within the polymer is enhanced 6-fold, and the total active layer absorption bandwidth is increased by 90 nm relative to the polymer:fullerene blend alone. We demonstrate that MoS2-organic heterojunctions can serve as hybrid solar cells, and their efficiencies can be improved using plasmonic metasurfaces.

  16. Absorption enhancement in thin film a-Si solar cells with double-sided SiO2 particle layers

    NASA Astrophysics Data System (ADS)

    Chen, Le; Wang, Qing-Kang; Shen, Xiang-Qian; Chen, Wen; Huang, Kun; Liu, Dai-Ming

    2015-10-01

    Light absorption enhancement is very important for improving the power conversion efficiency of a thin film a-Si solar cell. In this paper, a thin-film a-Si solar cell model with double-sided SiO2 particle layers is designed, and then the underlying mechanism of absorption enhancement is investigated by finite difference time domain (FDTD) simulation; finally the feasible experimental scheme for preparing the SiO2 particle layer is discussed. It is found that the top and bottom SiO2 particle layers play an important role in anti-reflection and light trapping, respectively. The light absorption of the cell with double-sided SiO2 layers greatly increases in a wavelength range of 300 nm-800 nm, and the ultimate efficiency increases more than 22% compared with that of the flat device. The cell model with double-sided SiO2 particle layers reported here can be used in varieties of thin film solar cells to further improve their performances. Project supported by the National High-Tech Research and Development Program of China (Grant No. 2011AA050518), the University Research Program of Guangxi Education Department, China (Grant No. LX2014288), and the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant No. 2013GXNSBA019014).

  17. Biological agent identification by nucleic acid base-pair analysis using surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Farquharson, Stuart; Smith, Wayne W.; Elliott, Susan; Sperry, Jay F.

    1999-01-01

    Recently, a number of analytical methods have been successfully developed which use nucleic acid sequencing to identify biological warfare agents. However, the effectiveness of these methods, towards the safety and protection of US Armed Forces and their allies are limited by the period required to enumerate the nucleic acid through polymerase chain reactions or culture growth to produce sufficient quantities for analysis. To overcome this limitation, we have been investigating the ability of surface-enhanced Raman spectroscopy to detect nucleic acids with sufficient sensitivity and selectivity to eliminate the need for enumeration. The design of a small volume electrolytic sample cell will be presented along with analysis of the nucleic acid bases and preliminary analysis of model bacteria.

  18. Enhancing Potentially Plant-Available Lead Concentrations in Contaminated Residential Soils Using a Biodegradable Chelating Agent

    NASA Astrophysics Data System (ADS)

    Andra, S.; Datta, R.; Sarkar, D.; Saminathan, S.

    2007-12-01

    Chelation of heavy metals is an important factor in enhancing metal solubility and, hence, metal availability to plants to promote phytoremediation. In the present study, we compared the effects of application of a biodegradable chelating agent, namely, ethylenediaminedisuccinic acid (EDDS) on enhancing plant available form of lead (Pb) in Pb-based paint contaminated residential soils compared to that of a more commonly used, but non-biodegradable chelate, i.e., ethylenediaminetetraacetic acid (EDTA). Development of a successful phytoremediation model for metals such as Pb depends on a thorough understanding of the physical and chemical properties of the soil, along with the optimization of a chelate treatment to mobilize Pb from `unavailable' pools to potentially plant available fraction. In this context, we set out to perform batch incubation experiments to investigate the effectiveness of the two aforementioned chelates in enhancing plant available Pb at four different concentrations (0, 5, 10 and 15 mM/kg soil) and three treatment durations (0, 10 and 30 days). We selected 12 contaminated residential soils from two major metropolitan areas (San Antonio, TX and Baltimore, MD) with varying soil physico-chemical properties - the soils from San Antonio were primarily alkaline and those from Baltimore were typically acidic. Total soil Pb concentrations ranged between 256 mg/kg and 4,182 mg/kg. Our results show that both chelates increased the solubility of Pb, otherwise occluded in the complex soil matrix. For both EDTA and EDDS, the exchangeable concentrations of soil Pb also increased with increase in chelate concentration and incubation time. The most effective treatment was 15 mM chelate kg-1 soil incubated for 30 days, which caused many fold increase in potentially plant available Pb (a combination of the soluble and exchangeable fractions) relative to the unamended controls. Step wise multiple linear regression analysis using chelate-extractable Pb and soil

  19. The ferroptosis inducer erastin enhances sensitivity of acute myeloid leukemia cells to chemotherapeutic agents.

    PubMed

    Yu, Yan; Xie, Yangchun; Cao, Lizhi; Yang, Liangchun; Yang, Minghua; Lotze, Michael T; Zeh, Herbert J; Kang, Rui; Tang, Daolin

    2015-01-01

    Acute myeloid leukemia (AML) is the most common type of leukemia in adults. Development of resistance to chemotherapeutic agents is a major hurdle in the effective treatment of patients with AML. The quinazolinone derivative erastin was originally identified in a screen for small molecules that exhibit synthetic lethality with expression of the RAS oncogene. This lethality was subsequently shown to occur by induction of a novel form of cell death termed ferroptosis. In this study we demonstrate that erastin enhances the sensitivity of AML cells to chemotherapeutic agents in an RAS-independent manner. Erastin dose-dependently induced mixed types of cell death associated with ferroptosis, apoptosis, necroptosis, and autophagy in HL-60 cells (AML, NRAS_Q61L), but not Jurkat (acute T-cell leukemia, RAS wild type), THP-1 (AML, NRAS_G12D), K562 (chronic myelogenous leukemia, RAS wild type), or NB-4 (acute promyelocytic leukemia M3, KRAS_A18D) cells. Treatment with ferrostatin-1 (a potent ferroptosis inhibitor) or necrostatin-1 (a potent necroptosis inhibitor), but not with Z-VAD-FMK (a general caspase inhibitor) or chloroquine (a potent autophagy inhibitor), prevented erastin-induced growth inhibition in HL-60 cells. Moreover, inhibition of c-JUN N-terminal kinase and p38, but not of extracellular signal-regulated kinase activation, induced resistance to erastin in HL-60 cells. Importantly, low-dose erastin significantly enhanced the anticancer activity of 2 first-line chemotherapeutic drugs (cytarabine/ara-C and doxorubicin/adriamycin) in HL-60 cells. Collectively, the induction of ferroptosis and necroptosis contributed to erastin-induced growth inhibition and overcame drug resistance in AML cells.

  20. Absorption enhancement in amorphous silicon thin films via plasmonic resonances in nickel silicide nanoparticles

    NASA Astrophysics Data System (ADS)

    Hachtel, Jordan; Shen, Xiao; Pantelides, Sokrates; Sachan, Ritesh; Gonzalez, Carlos; Dyck, Ondrej; Fu, Shaofang; Kalnayaraman, Ramki; Rack, Phillip; Duscher, Gerd

    2013-03-01

    Silicon is a near ideal material for photovoltaics due to its low cost, abundance, and well documented optical properties. The sole detriment of Si in photovoltaics is poor absorption in the infrared. Nanoparticle surface plasmon resonances are predicted to increase absorption by scattering to angles greater than the critical angle for total internal reflection (16° for a Si/air interface), trapping the light in the film. Experiments confirm that nickel silicide nanoparticles embedded in amorphous silicon increases absorption significantly in the infrared. However, it remains to be seen if electron-hole pair generation is increased in the solar cell, or whether the light is absorbed by the nanoparticles themselves. The nature of the absorption is explored by a study of the surface plasmon resonances through electron energy loss spectrometry and scanning transmission electron microscopy experiments, as well as first principles density functional theory calculations. Initial experimental results do not show strong plasmon resonances on the nanoparticle surfaces. Calculations of the optical properties of the nickel silicide particles in amorphous silicon are performed to understand why this resonance is suppressed. Work supported by NSF EPS 1004083 (TN-SCORE).

  1. Broadband absorption enhancement in plasmonic thin-film solar cells with grating surface

    NASA Astrophysics Data System (ADS)

    Liu, Li; Huo, Yiping; Zhao, Kaijun; Zhao, Ting; Li, Yuan

    2015-10-01

    The plasmonic thin-film solar cells with grating surface is structured and simulated by Comsol Multiphysics software using finite element method. The absorption efficiency of solar cells has been systemically studied by considering structure characteristic parameters. The absorption of grating surface cell is much broader and stronger than that of smooth surface on a-Si at the wavelength from 400 to 700 nm. The value of total absorption efficiency (TAE) increases from 47% to 69.3%. The embedded Ag nanoparticle array contributes to the improvement of the absorption of a-Si at longer wavelength range. The localized surface plasmon resonance is induced by Ag nanoparticles, and so that the TAE is increased to 75.1% when the radius of nanoparticle is 60 nm at the bottom of a-Si with periodic width 200 nm. The grating surface always plays a role to suppress light scattering from the active region, so more light can be absorbed again by a-Si in the infrared-region. Therefore, the results have significance in providing a theoretical foundation for the applications of thin-film solar cell.

  2. Oral Absorption Enhancement of Probucol by PEGylated G5 PAMAM Dendrimer Modified Nanoliposomes

    PubMed Central

    Ma, Qian; Han, Yingchun; Chen, Cong; Cao, Yini; Wang, Siling; Shen, Wenwen; Zhang, Huayu; Li, Yanzhi; van Dongen, Mallory A.; He, Bing; Yu, Maomao; Xu, Lu; Banaszak Holl, Mark M.; Liu, George; Zhang, Qiang; Qi, Rong

    2016-01-01

    Probucol (PB), an antioxidant drug, is commonly used as a lipid concentration lowering drug to reduce blood plasma cholesterol levels in the clinic. However, the therapeutic effects of this drug are negatively impacted by its poor water solubility and low oral absorption efficiency. In this study, a PEGylated G5 PAMAM dendrimer (G5-PEG) modified nanoliposome was employed to increase water solubility, transepithelial transport, and oral absorption of PB. The uptake mechanism was explored in vitro in Caco-2 cells with the results suggesting that the absorption improvement of G5-PEG modified PB-liposome (PB-liposome/G5-PEG) was related to P-glycoprotein (P-gp) efflux pump, but was independent of caveolae endocytosis pathways. Additionally, plasma lipid concentration lowering effects of PB-liposome/G5-PEG were evaluated in vivo in a LDLR−/− hyperlipidemia mouse model. Compared with saline treated group, treatment with PB-liposome/G5-PEG significantly inhibited the increase of plasma total cholesterol (TC) and triglyceride (TG) of mice induced by a high fat diet. Moreover, its lipid concentration lowering effects and plasma drug concentration were greater than PB alone or commercial PB tablets. Our results demonstrated that PB-liposome/G5-PEG significantly increased the oral absorption of PB and therefore, significantly improved its pharmacodynamic effects. PMID:25587935

  3. Clay ingestion enhances intestinal triacylglycerol hydrolysis and non-esterified fatty acid absorption.

    PubMed

    Habold, Caroline; Reichardt, François; Le Maho, Yvon; Angel, Fabielle; Liewig, Nicole; Lignot, Jean-Hervé; Oudart, Hugues

    2009-07-01

    Consumption by animals and humans of earthy materials such as clay is often related to gut pathologies. Our aim was to determine the impact of kaolinite ingestion on glucose and NEFA transport through the intestinal mucosa. The expression of hexose transporters (Na/glucose co-transporter 1 (SGLT1), GLUT2, GLUT5) and of proteins involved in NEFA absorption (fatty acid transporter/cluster of differentiation 36 (FAT/CD36), fatty acid transport protein 4 (FATP4) and liver fatty acid binding protein (L-FABP)) was measured (1) in rats whose jejunum was perfused with a solution of kaolinite, and (2) in rats who ate spontaneously kaolinite pellets during 7 and 28 d. Also, we determined TAG and glucose absorption in the kaolinite-perfused group, and pancreatic lipase activity, gastric emptying and intestinal transit in rats orally administered with kaolinite. Glucose absorption was not affected by kaolinite perfusion or ingestion. However, kaolinite induced a significant increase in intestinal TAG hydrolysis and NEFA absorption. The cytoplasmic expression of L-FABP and FATP4 also increased due to kaolinite ingestion. NEFA may enter the enterocytes via endocytosis mainly since expression of NEFA transporters in the brush-border membrane was not affected by kaolinite. After uptake, rapid binding of NEFA by L-FABP and FATP4 could act as an intracellular NEFA buffer to prevent NEFA efflux. Increased TAG hydrolysis and NEFA absorption may be due to the adsorption properties of clay and also because kaolinite ingestion caused a slowing down of gastric emptying and intestinal transit.

  4. A broadband cavity enhanced absorption spectrometer for aircraft measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water vapor

    NASA Astrophysics Data System (ADS)

    Min, K.-E.; Washenfelder, R. A.; Dubé, W. P.; Langford, A. O.; Edwards, P. M.; Zarzana, K. J.; Stutz, J.; Lu, K.; Rohrer, F.; Zhang, Y.; Brown, S. S.

    2016-02-01

    We describe a two-channel broadband cavity enhanced absorption spectrometer (BBCEAS) for aircraft measurements of glyoxal (CHOCHO), methylglyoxal (CH3COCHO), nitrous acid (HONO), nitrogen dioxide (NO2), and water (H2O). The instrument spans 361-389 and 438-468 nm, using two light-emitting diodes (LEDs) and a single grating spectrometer with a charge-coupled device (CCD) detector. Robust performance is achieved using a custom optical mounting system, high-power LEDs with electronic on/off modulation, high-reflectivity cavity mirrors, and materials that minimize analyte surface losses. We have successfully deployed this instrument during two aircraft and two ground-based field campaigns to date. The demonstrated precision (2σ) for retrievals of CHOCHO, HONO and NO2 are 34, 350, and 80 parts per trillion (pptv) in 5 s. The accuracy is 5.8, 9.0, and 5.0 %, limited mainly by the available absorption cross sections.

  5. A broadband cavity enhanced absorption spectrometer for aircraft measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water vapor

    NASA Astrophysics Data System (ADS)

    Min, K.-E.; Washenfelder, R. A.; Dubé, W. P.; Langford, A. O.; Edwards, P. M.; Zarzana, K. J.; Stutz, J.; Lu, K.; Rohrer, F.; Zhang, Y.; Brown, S. S.

    2015-10-01

    We describe a two-channel broadband cavity enhanced absorption spectrometer (BBCEAS) for aircraft measurements of glyoxal (CHOCHO), methylglyoxal (CH3COCHO), nitrous acid (HONO), nitrogen dioxide (NO2), and water (H2O). The instrument spans 361-389 and 438-468 nm, using two light emitting diodes (LEDs) and a grating spectrometer with a charge-coupled device (CCD) detector. Robust performance is achieved using a custom optical mounting system, high power LEDs with electronic on/off modulation, state-of-the-art cavity mirrors, and materials that minimize analyte surface losses. We have successfully deployed this instrument during two aircraft and two ground-based field campaigns to date. The demonstrated precision (2σ) for retrievals of CHOCHO, HONO and NO2 are 34, 350 and 80 pptv in 5 s. The accuracy is 5.8, 9.0 and 5.0 % limited mainly by the available absorption cross sections.

  6. Enhanced carrier collection efficiency and reduced quantum state absorption by electron doping in self-assembled quantum dot solar cells

    NASA Astrophysics Data System (ADS)

    Li, Tian; Lu, Haofeng; Fu, Lan; Tan, Hark Hoe; Jagadish, Chennupati; Dagenais, Mario

    2015-02-01

    Reduced quantum dot (QD) absorption due to state filling effects and enhanced electron transport in doped QDs are demonstrated to play a key role in solar energy conversion. Reduced QD state absorption with increased n-doping is observed in the self-assembled In0.5Ga0.5As/GaAs QDs from high resolution below-bandgap external quantum efficiency (EQE) measurement, which is a direct consequence of the Pauli exclusion principle. We also show that besides partial filling of the quantum states, electron-doping produces negatively charged QDs that exert a repulsive Coulomb force on the mobile electrons, thus altering the electron trajectory and reducing the probability of electron capture, leading to an improved collection efficiency of photo-generated carriers, as indicated by an absolute above-bandgap EQE measurement. The resulting redistribution of the mobile electron in the planar direction is further validated by the observed photoluminescence intensity dependence on doping.

  7. Detection of HO2 in an atmospheric pressure plasma jet using optical feedback cavity-enhanced absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Gianella, Michele; Reuter, Stephan; Lawry Aguila, Ana; Ritchie, Grant A. D.; van Helden, Jean-Pierre H.

    2016-11-01

    Cold non-equilibrium atmospheric pressure plasma jets are increasingly applied in material processing and plasma medicine. However, their small dimensions make diagnosing the fluxes of generated species a challenge. Here we report on the detection of the hydroperoxyl radical, HO2, in the effluent of a plasma jet by the use of optical feedback cavity-enhanced absorption spectroscopy. The spectrometer has a minimum detectable absorption coefficient {α }\\min of 2.25× {10}-10 cm-1 with a 100 second acquisition, equivalent to 5.5× {10}12 {{cm}}-3 of HO2 (under ideal conditions). Concentrations in the range of (3.1-7.8) × 1013 cm-3 were inferred in the 4 mm wide effluent of the plasma jet.

  8. Absorption enhancement by matching the cross-section of plasmonic nanowires to the field structure of tightly focused beams.

    PubMed

    Normatov, Alexander; Spektor, Boris; Leviatan, Yehuda; Shamir, Joseph

    2011-04-25

    Nanostructured materials, designed for enhanced light absorption, are receiving increased scientific and technological interest. In this paper we propose a physical criterion for designing the cross-sectional shape of plasmonic nanowires for improved absorption of a given tightly focused illumination. The idea is to design a shape which increases the matching between the nanowire plasmon resonance field and the incident field. As examples, we design nanowire shapes for two illumination cases: a tightly focused plane wave and a tightly focused beam containing a line singularity. We show that properly shaped and positioned silver nanowires that occupy a relatively small portion of the beam-waist area can absorb up to 65% of the total power of the incident beam.

  9. Omnidirectional and polarization-insensitive light absorption enhancement in an organic photovoltaic device using a one-dimensional nanograting

    NASA Astrophysics Data System (ADS)

    Tian, Ximin; Wang, Wenyan; Hao, Yuying; Lin, Yinyue; Cui, Yanxia; Zhang, Ye; Wang, Hua; Wei, Bin; Xu, Bingshe

    2014-12-01

    A novel poly-3-hexylthiophene (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) solar cell was designed with both the silver cathode and the organic layers structured into one-dimensional periodic patterns. Its optical behavior was investigated systematically by the finite element method. The numerical results indicate that a broadband, omnidirectional, and polarization-insensitive light absorption enhancement is realized by utilizing this structure. This is attributed to the simultaneous excitation of both plasmonic and photonic modes by particular structural designs. Moreover, the increased absorption allows for the use of very thin active layers, resulting in decreased losses of charge carriers transporting to the electrodes. Therefore, this proposal is expected to find potential applications in organic solar cells for improving the overall device performance.

  10. Optical absorption enhancement in 40 nm ultrathin film silicon solar cells assisted by photonic and plasmonic modes

    NASA Astrophysics Data System (ADS)

    Saravanan, S.; Dubey, R. S.

    2016-10-01

    Presently, energy problems and environmental issues have attracted the scientific community for the development of cost-effective and high-performance solar cells. Thin film solar cells are cheaper but weak light absorption in longer wavelength has demanded an efficient light trapping scheme for the better harvesting of solar radiation to a maximum possibility. In this paper, we numerically explore the design efforts of an ultrathin film silicon solar cell, integrated with top dielectric and bottom metal gratings. The proposed design is influenced by the localized surface plasmon modes, surface plasmon polariton and optical resonances which leads to the optimal harvesting of sunlight within 40 nm thick absorbing layer. The optimized design of solar cell shows enhanced light absorption with cell efficiency ∼25% at normal transverse magnetic polarization condition. Our design approach assisted by photonic and plasmonic modes is promising for the realization of new generation, low-cost ultrathin film solar cells.

  11. Determination of Lead in Water Samples Using a New Vortex-Assisted, Surfactant-Enhanced Emulsification Liquid-Liquid Microextraction Combined with Graphite Furnace Atomic Absorption Spectrometry.

    PubMed

    Peng, Guilong; He, Qiang; Lu, Ying; Mmereki, Daniel; Pan, Weiliang; Tang, Xiaohui; Zhou, Guangming; Mao, Yufeng; Su, Xaioxuan

    2016-04-01

    A low toxic solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction (LT-VSLLME) combined with graphite furnace atomic absorption spectrometry was developed for the extraction and determination of lead (Pb) in water samples. In the LT-VSLLME method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Meanwhile, the addition of a surfactant, which acted as an emulsifier, could enhance the speed of the mass-transfer from aqueous samples to the extraction solvent. The influences of analytical parameters, including extraction solvent type and its volume, surfactant type and its volume, pH, concentration of chelating agent, salt effect and extraction time were investigated. Under the optimized conditions, a good relative standard deviation of 3.69% at 10 ng L(-1) was obtained. The calibration graph showed a linear pattern in the ranges of 5-30 ngL(-1), with a limit of detection of 0.76 ng L(-1). The linearity was obtained by five points in the concentration range of 5-30 ngL(-1). The enrichment factor was 320. The procedure was applied to wastewater and river water, and the accuracy was assessed through the analysis of the recovery experiments.

  12. Measurement of nitrous acid (HONO) by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Yi, Hongming; Maamary, Rabih; Gao, Xiaoming; Sigrist, Markus W.; Fertein, Eric; Chen, Weidong

    2016-04-01

    Spectroscopic detection of short-lived gaseous nitrous acid (HONO) at 1254.85 cm-1 was realized by off-beam coupled quartz-enhanced photoacoustic spectroscopy (QEPAS) in conjunction with an external cavity quantum cascade lasers (EC-QCL). High sensitivity monitoring of HONO was performed within a very small gas-sample volume (of ~40 mm3) allowing a significant reduction (of about 4 orders of magnitude) of air sampling residence time which is highly desired for accurate quantification of chemically reactive short-lived species. Calibration of the developed QEPAS-based HONO sensor was carried out by means of lab-generated HONO samples whose concentrations were determined by simultaneous measurements of direct HONO absorption spectra in a 109.5 m multipass cell using a distributed feedback (DBF) QCL. A minimum detection limit (MDL @ SNR=1) of 66 ppbv HONO was achieved at 70 mbar using a laser output power of 50 mW and 1 s integration time, which corresponded to a normalized noise equivalent absorption coefficient of 3.6×10-8 cm-1.W/Hz1/2. This MDL was down to 7 ppbv at the optimal integration time of 150 s. The corresponding minimum detected absorption coefficient (SNR=1) is ~1.1×10-7 cm-1 (MDL: ~3 ppbv) in 1 s and ~1.1×10-8 cm-1 (MDL~330 pptv) in 150 s, respectively, with 1 W laser power. Acknowledgements The authors acknowledge financial supports from the CaPPA project (ANR-10-LABX-005) and the CPER CLIMIBIO program. References H. Yi, R. Maamary, X. Gao, M. W. Sigrist, E. Fertein, W. Chen, "Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy", Appl. Phys. Lett. 106 (2015) 101109

  13. Use of staurosporine, an actin-modifying agent, to enhance fibrochondrocyte matrix gene expression and synthesis.

    PubMed

    Hoben, Gwendolyn M; Athanasiou, Kyriacos A

    2008-12-01

    Modulation of the actin cytoskeleton in chondrocytes has been used to prevent or reverse dedifferentiation and to enhance protein synthesis. We have hypothesized that an actin-modifying agent, staurosporine, could be used with fibrochondrocytes to increase the gene expression and synthesis of critical fibrocartilage proteins. A range of concentrations (0.1-100 nM) was applied to fibrochondrocytes in monolayer and evaluated after 24 h and after 4 days. High-dose staurosporine treatment (10-100 nM) increased cartilage oligomeric matrix protein 60- to 500-fold and aggrecan gene expression two-fold. This effective range of staurosporine was then applied to scaffoldless tissue-engineered fibrochondrocyte constructs for 4 weeks. Whereas glycosaminoglycan synthesis was not affected, collagen content doubled, from 27.6 +/- 8.8 microg in the untreated constructs to 55.2 +/- 12.2 microg per construct with 100 nM treatment. When analyzed for specific collagens, the 10-nM group showed a significant increase in collagen type I content, whereas collagen type II was unaffected. A concomitant dose-dependent reduction was noted in construct contraction, reflecting the actin-disrupting action of staurosporine. Thus, staurosporine increases the gene expression for important matrix proteins and can be used to enhance matrix production and reduce contraction in tissue-engineered fibrocartilage constructs.

  14. Bitter melon extracts enhance the activity of chemotherapeutic agents through the modulation of multiple drug resistance

    PubMed Central

    Kwatra, Deep; Venugopal, Anand; Standing, David; Ponnurangam, Sivapriya; Dhar, Animesh; Mitra, Ashim; Anant, Shrikant

    2014-01-01

    Recently we demonstrated that extracts of bitter melon (BME) can be used as a preventive/therapeutic agent in colon cancers. Here, we determined BME effects on anticancer activity and bioavailability of doxorubicin (DOX) in colon cancer cells. BME enhanced the effect of DOX on cell proliferation and sensitized the cells towards DOX upon pretreatment. Furthermore, there was both increased drug uptake and reduced drug efflux. We also observed a reduction in the expression of Multidrug resistance conferring proteins (MDRCP) P-glycoprotein, MRP-2 and BCRP. Further BME suppressed DOX efflux in MDCK cells overexpressing the three efflux proteins individually, suggesting that BME is a potent inhibitor of MDR function. Next, we determined the effect of BME on PXR, a xenobiotic sensing nuclear receptor and a transcription factor that controls the expression of the three MDR genes. BME suppressed PXR promoter activity thereby suppressing its expression. Finally, we determined the effect of AMPK pathway on drug efflux because we have previously demonstrated that BME affects the pathway. However, inhibiting AMPK did not affect drug resistance, suggesting that BME may use different pathways for the anticancer and MDR modulating activities. Together, these results suggest that BME can enhance the bioavailability and efficacy of conventional chemotherapy. PMID:24129966

  15. Sound absorption enhancement of nonwoven felt by using coupled membrane - sonic crystal inclusion

    NASA Astrophysics Data System (ADS)

    Fitriani, M. C.; Yahya, I.; Harjana; Ubaidillah; Aditya, F.; Siregar, Y.; Moeliono, M.; Sulaksono, S.

    2016-11-01

    The experimental results from laboratory test on the sound absorption performance of nonwoven felt with an array thin tubes and sonic crystal inclusions reported in this paper. The nonwoven felt sample was produced by a local company with 15 mm in its thickness and 900 gsm. The 6.4 mm diameter plastic straw was used to construct the thin tubes array while the sonic crystal is arranged in a 4 × 4 lattice crystal formation. It made from a PVC cylinder with 17 mm and 50 mm in diameter and length respectively. All cylinders have two holes positioned on 10 mm and 25 mm from the base. The results show that both treatments, array of thin tube and sonic crystal inclusions are effectively increased the sound absorption coefficient of the nonwoven felt significantly especially in the low frequency range starting from 200Hz.

  16. Soluplus® as an effective absorption enhancer of poorly soluble drugs in vitro and in vivo.

    PubMed

    Linn, Michael; Collnot, Eva-Maria; Djuric, Dejan; Hempel, Katja; Fabian, Eric; Kolter, Karl; Lehr, Claus-Michael

    2012-02-14

    As many new active pharmaceutical ingredients are poorly water soluble, solubility enhancers are one possibility to overcome the hurdles of drug dissolution and absorption in oral drug delivery. In the present work a novel solubility enhancing excipient (Soluplus®) was tested for its capability to improve intestinal drug absorption. BCS class II compounds danazol, fenofibrate and itraconazole were tested both in vivo in beagle dogs and in vitro in transport experiments across Caco-2 cell monolayers. Each drug was applied as pure crystalline substance, in a physical mixture with Soluplus®, and as solid solution of the drug in the excipient. In the animal studies a many fold increase in plasma AUC was observed for the solid solutions of drug in Soluplus® compared to the respective pure drug. An effect of Soluplus® in a physical mixture with the drug could be detected for fenofibrate. In vitro transport studies confirm the strong effect of Soluplus® on the absorption behavior of the three tested drugs. Furthermore, the increase of drug flux across Caco-2 monolayer is correlating to the increase in plasma AUC and C(max)in vivo. For these poorly soluble substances Soluplus® has a strong potential to improve oral bioavailability. The applicability of Caco-2 monolayers as tool for predicting the in vivo transport behavior of the model drugs in combination with a solubility enhancing excipient was shown. Also the improvement of a solid dispersion compared to physical mixtures of the drugs and the excipient was correctly reflected by Caco-2 experiments. In the case of fenofibrate the possible improvement by a physical mixture was demonstrated, underscoring the value of the used tool as alternative to animal studies.

  17. Enhancement effect of P-gp inhibitors on the intestinal absorption and antiproliferative activity of bestatin.

    PubMed

    Huo, Xiaokui; Liu, Qi; Wang, Changyuan; Meng, Qiang; Sun, Huijun; Peng, Jinyong; Ma, Xiaochi; Liu, Kexin

    2013-11-20

    Bestatin is an immunomodulator with antitumor activity. This study was performed to investigate the effect of P-gp on the intestinal absorption and antiproliferative activity of bestatin. Our results showed that P-gp inhibitors significantly increased rat intestinal absorption of bestatin in vivo and in vitro. The net efflux ratio of bestatin was 2.2 across mock-/MDR1-MDCK cell monolayers and was decreased by P-gp inhibitors, indicating bestatin was a substrate of P-gp. Furthermore, the IC50 values of bestatin on U937 and K562 cells were decreased dramatically and the intracellular concentrations of bestatin were increased by incubation of cells with verapamil or Cyclosporin A. K562/ADR cells exhibited a higher IC50 value and a lower intracellular level of bestatin. The bestatin level in K562/ADR cells was partially restored by incubation with doxorubicin. However, P-gp and APN mRNA levels were not changed by bestatin. These results suggested that the intestinal absorption and accumulation in cancer cells for bestatin were limited by P-gp-mediated efflux. Additional attention should be paid to the alternative exposure of bestatin when bestatin was coadministered with drugs as P-gp substrates in clinic.

  18. Enhancing rigid frame porous layer absorption with three-dimensional periodic irregularities.

    PubMed

    Groby, J-P; Brouard, B; Dazel, O; Nennig, B; Kelders, L

    2013-02-01

    This papers reports a three-dimensional (3D) extension of the model proposed by Groby et al. [J. Acoust. Soc. Am. 127, 2865-2874 (2010)]. The acoustic properties of a porous layer backed by a rigid plate with periodic rectangular irregularities are investigated. The Johnson-Champoux-Allard model is used to predict the complex bulk modulus and density of the equivalent fluid in the porous material. The method of variable separation is used together with the radiation conditions and Floquet theorem to derive the analytical expression for the acoustic reflection coefficient from the porous layer with 3D inhomogeneities. Finite element method is also used to validate the proposed analytical solution. The theoretical and numerical predictions agree well with the experimental data obtained from an impedance tube experiment. It is shown that the measured acoustic absorption coefficient spectrum exhibits a quasi-total absorption peak at the predicted frequency of the mode trapped in the porous layer. When more than one irregularity per spatial period is considered, additional absorption peaks are observed.

  19. Enhanced relaxivity of Gd3+-based contrast agents geometrically confined within porous nanoconstructs

    PubMed Central

    Sethi, Richa; Ananta, Jeyarama S.; Karmonik, Christof; Zhong, Meng; Fung, Steve H.; Liu, Xuewu; Li, King; Ferrari, Mauro; Wilson, Lon J.; Decuzzi, Paolo

    2013-01-01

    Gadolinium chelates, which are currently approved for clinical MRI use, provide relaxivities well below their theoretical limit, and they also lack tissue specificity. Recently, the geometrical confinement of Gd3+-based contrast agents (CAs) within porous structures has been proposed as a novel, alternative strategy to improve relaxivity without chemical modification of the CA. Here, we have characterized and optimized the performance of MRI nanoconstructs obtained by loading [Gd(DTPA)(H2O)]2− (Magnevist®) into the pores of injectable mesoporous silicon particles. Nanoconstructs with three different pore sizes were studied, and at 60 MHz, they exhibited longitudinal relaxivities of ~ 24 mM−1s−1 for 5 – 10 nm pores and ~ 10 mM−1s−1 for 30 – 40 nm pores. No enhancement in relaxivity was observed for larger pores sizes. Using an outer-sphere compound, [GdTTHA]−3, and mathematical modeling, it was demonstrated that the relaxivity enhancement is due to the increase in rotational correlation times (CA adsorbed on the pore walls) and diffusion correlation times (reduced mobility of the water molecules), as the pore sizes decreases. It was also observed that extensive CA adsorption on the outer surface of the silicon particles negates the advantages offered by nanoscale confinement. Upon incubation with HeLa cells, the nanoconstructs did not demonstrate significant cytotoxicity for up to 3 days post incubation, at different particle/cell ratios. In addition, the nanoconstructs showed complete degradation after 24h of continuous agitation in PBS. These data support and confirm the hypothesis that the geometrical confinement of Gd3+-chelate compounds into porous structures offers MRI nanoconstructs with enhanced relaxivity (up to 6 times for [Gd(DTPA)(H2O)]2−, and 4 times for [GdTTHA]−3) and, potentially, improved stability, reduced toxicity and tissue specificity. PMID:22991316

  20. Feasibility study of SWIR light absorption enhancement in PbS and PbSe nano-structure layers using surface plasmon polariton

    NASA Astrophysics Data System (ADS)

    Nissim, Nimrod; Rosenblit, Michael; Sarusi, Gabby

    2017-03-01

    We present a theoretical feasibility study of the use of reflection grating couplers in order to harness the Surface Plasmon Polariton (SPP) to increase the absorption efficiency in the short wavelength infrared (SWIR) spectral range of a novel SWIR to visible (VIS) direct up-conversion imaging device. This device detects the SWIR spectral band photons using high absorption PbSe/CdSe core-shell, PbS nano-spheres or PbSe nano-columns. In order to further enhance the absorption of the SWIR light within the nano-structure layer we propose to add another light absorption enhancement, known as SPP enhanced absorption. The idea is to cover the absorber layer surface with a structured metal layer that will ignite SPPs on the metal - dielectric interface, by coupling between the incident TM polarized photons and the SPP modes; this results in better field confinement at the interface that will further increase the SWIR absorption of this thin layer. Calculation of the field profile of the surface plasmon (SP) in the SWIR range shows perpendicular dominance of the SP's electrical field direction on the dielectric layer side (the PbS or PbSe/CdSe absorption layer side). Based on this result, it was found that, due to the use of quantum confined and, thus, high oscillator strength nanostructures, there is only a marginal increase in the absorption and, hence, in the quantum efficiency when using the SPP enhancement technique. Nevertheless, we show that one of the proposed configurations of the metal grating coupler, having a lamellar structure with a pitch of 1.38μm, a duty cycle (DC) of 0.12μm and a height of 60nm, is predicted to increase the total layer's absorption by 9.5%, mainly due to efficient light scattering rather than to SPP enhanced absorption.

  1. Using active resonator impedance matching for shot-noise limited, cavity enhanced amplitude modulated laser absorption spectroscopy.

    PubMed

    Chow, Jong H; Littler, Ian C M; Rabeling, David S; McClelland, David E; Gray, Malcolm B

    2008-05-26

    We introduce a closed-loop feedback technique to actively control the coupling condition of an optical cavity, by employing amplitude modulation of the interrogating laser. We show that active impedance matching of the cavity facilitates optimal shot-noise sensing performance in a cavity enhanced system, while its control error signal can be used for intra-cavity absorption or loss signal extraction. We present the first demonstration of this technique with a fiber ring cavity, and achieved shot-noise limited loss sensitivity. We also briefly discuss further use of impedance matching control as a tool for other applications.

  2. Applying gold nanoparticles as tumor-vascular disrupting agents during brachytherapy: estimation of endothelial dose enhancement

    NASA Astrophysics Data System (ADS)

    Ngwa, Wilfred; Makrigiorgos, G. Mike; Berbeco, Ross I.

    2010-11-01

    Tumor vascular disrupting agents (VDAs) represent a promising approach to the treatment of cancer, in view of the tumor vasculature's pivotal role in tumor survival, growth and metastasis. VDAs targeting the tumor's dysmorphic endothelial cells can cause selective and rapid occlusion of the tumor vasculature, leading to tumor cell death from ischemia and extensive hemorrhagic necrosis. In this study, the potential for applying gold nanoparticles (AuNPs) as VDAs, during brachytherapy, is examined. Analytic calculations based on the electron energy loss formula of Cole were carried out to estimate the endothelial dose enhancement caused by radiation-induced photo/Auger electrons originating from AuNPs targeting the tumor endothelium. The endothelial dose enhancement factor (EDEF), representing the ratio of the dose to the endothelium with and without gold nanoparticles was calculated for different AuNP local concentrations, and endothelial cell thicknesses. Four brachytherapy sources were investigated, I-125, Pd-103, Yb-169, as well as 50 kVp x-rays. The results reveal that, even at relatively low intra-vascular AuNP concentrations, ablative dose enhancement to tumor endothelial cells due to photo/Auger electrons from the AuNPs can be achieved. Pd-103 registered the highest EDEF values of 7.4-271.5 for local AuNP concentrations ranging from 7 to 350 mg g-1, respectively. Over the same concentration range, I-125, 50 kVp and Yb-169 yielded values of 6.4-219.9, 6.3-214.5 and 4.0-99.7, respectively. Calculations of the EDEF as a function of endothelial cell thickness showed that lower energy sources like Pd-103 reach the maximum EDEF at smaller thicknesses. The results also reveal that the highest contribution to the EDEF comes from Auger electrons, apparently due to their shorter range. Overall, the data suggest that ablative dose enhancement to tumor endothelial cells can be achieved by applying tumor vasculature-targeted AuNPs as adjuvants to brachytherapy, with lower

  3. Development of gold induced surface plasmon enhanced CIGS absorption layer on polyimide substrate

    NASA Astrophysics Data System (ADS)

    Park, Seong-Un; Sharma, Rahul; Sim, Jae-Kwan; Baek, Byung Joon; Ahn, Haeng-Kwun; Kim, Jin Soo; Lee, Cheul-Ro

    2013-09-01

    Localized surface plasmon resonance (LSPR) with metal nanoparticles is the promising phenomenon to increase light absorption by trapping light in thin film solar cells. In this study we demonstrate a successful LSPR effect with gold (Au) nanoparticles onto the Cu(In,Ga)Se2 (CIGS) absorption layer. First, the CIGS absorber layers is fabricated onto the Mo coated polyimide (PI) substrate by using two stage process as DC sputtering of CIG thin film followed by the selenization at 400 °C. Finally, the Au nanoparticles are deposited onto the CIGS layer with increasing particles size from 4-15 nm by using sputter coater for 10-120 s. The X-ray diffraction (XRD) patterns confirm the formation of CIGS/Au nanocomposite structure with prominent peak shift of CIGS reflections and increasing intensity for Au phase. The CIGS/Au nanocomposite morphologies with Au particle size distribution uniformity and surface coverage is examined under ultra-high resolution field effect scanning electron microscope (UHR-FESEM). A peak at 176 cm-1 in Raman spectra, associated with the “A1” mode of lattice vibration for the attributed to the pure chalcopyrite structure. The secondary ion mass spectroscopy (SIMS) showed ∼200 nm depth converge of Au nanoparticles into the CIGS absorption layer. The optical properties as transmittance, reflectance and absorbance of CIGS/Au layers were found to expand in the infrared region and the LSPR effect is the most prominent for Au particles (5-7 nm) deposited for 60 s. The absorption coefficient and band gap measurement also confirms that the LSPR effect for 5-7 nm Au particles with band gap improvement from 1.31 to 1.52 eV for CIGS/Au layer as the defect density decreases due to the deposition of Au nanoparticles onto the CIGS layer. Such LSPR effect in CIGS/Au nanocomposite absorption layer will be a key parameter to further improve performance of the solar cell.

  4. Reflux-free cannula for convection-enhanced high-speed delivery of therapeutic agents

    PubMed Central

    Krauze, Michal T.; Saito, Ryuta; Noble, Charles; Tamas, Matyas; Bringas, John; Park, John W.; Berger, Mitchel S.; Bankiewicz, Krystof

    2013-01-01

    Object Clinical application of the convection-enhanced delivery (CED) technique is currently limited by low infusion speed and reflux of the delivered agent. The authors developed and evaluated a new step-design cannula to overcome present limitations and to introduce a rapid, reflux-free CED method for future clinical trials. Methods The CED of 0.4% trypan blue dye was performed in agarose gel to test cannula needles for distribution and reflux. Infusion rates ranging from 0.5 to 50 μl/minute were used. Agarose gel findings were translated into a study in rats and then in cynomolgus monkeys (Macaca fascicularis) by using trypan blue and liposomes to confirm the efficacy of the reflux-free step-design cannula in vivo. Results of agarose gel studies showed reflux-free infusion with high flow rates using the step-design cannula. Data from the study in rats confirmed the agarose gel findings and also revealed increasing tissue damage at a flow rate above 5-μl/minute. Robust reflux-free delivery and distribution of liposomes was achieved using the step-design cannula in brains in both rats and nonhuman primates. Conclusions The authors developed a new step-design cannula for CED that effectively prevents reflux in vivo and maximizes the distribution of agents delivered in the brain. Data in the present study show reflux-free infusion with a constant volume of distribution in the rat brain over a broad range of flow rates. Reflux-free delivery of liposomes into nonhuman primate brain was also established using the cannula. This step-design cannula may allow reflux-free distribution and shorten the duration of infusion in future clinical applications of CED in humans. PMID:16304999

  5. Spectroscopic characterization of biological agents using FTIR, normal Raman and surface-enhanced Raman spectroscopies

    NASA Astrophysics Data System (ADS)

    Luna-Pineda, Tatiana; Soto-Feliciano, Kristina; De La Cruz-Montoya, Edwin; Pacheco Londoño, Leonardo C.; Ríos-Velázquez, Carlos; Hernández-Rivera, Samuel P.

    2007-04-01

    FTIR, Raman spectroscopy and Surface Enhanced Raman Scattering (SERS) requires a minimum of sample allows fast identification of microorganisms. The use of this technique for characterizing the spectroscopic signatures of these agents and their stimulants has recently gained considerable attention due to the fact that these techniques can be easily adapted for standoff detection from considerable distances. The techniques also show high sensitivity and selectivity and offer near real time detection duty cycles. This research focuses in laying the grounds for the spectroscopic differentiation of Staphylococcus spp., Pseudomonas spp., Bacillus spp., Salmonella spp., Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, and E. coli, together with identification of their subspecies. In order to achieve the proponed objective, protocols to handle, cultivate and analyze the strains have been developed. Spectroscopic similarities and marked differences have been found for Spontaneous or Normal Raman spectra and for SERS using silver nanoparticles have been found. The use of principal component analysis (PCA), discriminate factor analysis (DFA) and a cluster analysis were used to evaluate the efficacy of identifying potential threat bacterial from their spectra collected on single bacteria. The DFA from the bacteria Raman spectra show a little discrimination between the diverse bacterial species however the results obtained from the SERS demonstrate to be high discrimination technique. The spectroscopic study will be extended to examine the spores produced by selected strains since these are more prone to be used as Biological Warfare Agents due to their increased mobility and possibility of airborne transport. Micro infrared spectroscopy as well as fiber coupled FTIR will also be used as possible sensors of target compounds.

  6. Ultrasound-enhanced thrombolysis using Definity as a cavitation nucleation agent.

    PubMed

    Datta, Saurabh; Coussios, Constantin-C; Ammi, Azzdine Y; Mast, T Douglas; de Courten-Myers, Gabrielle M; Holland, Christy K

    2008-09-01

    Ultrasound has been shown previously to act synergistically with a thrombolytic agent, such as recombinant tissue plasminogen activator (rt-PA) to accelerate thrombolysis. In this in vitro study, a commercial contrast agent, Definity, was used to promote and sustain the nucleation of cavitation during pulsed ultrasound exposure at 120 kHz. Ultraharmonic signals, broadband emissions and harmonics of the fundamental were measured acoustically by using a focused hydrophone as a passive cavitation detector and used to quantify the level of cavitation activity. Human whole blood clots suspended in human plasma were exposed to a combination of rt-PA, Definity and ultrasound at a range of ultrasound peak-to-peak pressure amplitudes, which were selected to expose clots to various degrees of cavitation activity. Thrombolytic efficacy was determined by measuring clot mass loss before and after the treatment and correlated with the degree of cavitation activity. The penetration depth of rt-PA and plasminogen was also evaluated in the presence of cavitating microbubbles using a dual-antibody fluorescence imaging technique. The largest mass loss (26.2%) was observed for clots treated with 120-kHz ultrasound (0.32-MPa peak-to-peak pressure amplitude), rt-PA and stable cavitation nucleated by Definity. A significant correlation was observed between mass loss and ultraharmonic signals (r = 0.85, p < 0.0001, n = 24). The largest mean penetration depth of rt-PA (222 microm) and plasminogen (241 microm) was observed in the presence of stable cavitation activity. Stable cavitation activity plays an important role in enhancement of thrombolysis and can be monitored to evaluate the efficacy of thrombolytic treatment.

  7. Variants of Phosphotriesterase for the Enhanced Detoxification of the Chemical Warfare Agent VR.

    PubMed

    Bigley, Andrew N; Mabanglo, Mark F; Harvey, Steven P; Raushel, Frank M

    2015-09-08

    The V-type organophosphorus nerve agents are among the most hazardous compounds known. Previous efforts to evolve the bacterial enzyme phosphotriesterase (PTE) for the hydrolytic decontamination of VX resulted in the identification of the variant L7ep-3a, which has a kcat value more than 2 orders of magnitude higher than that of wild-type PTE for the hydrolysis of VX. Because of the relatively small size of the O-ethyl, methylphosphonate center in VX, stereoselectivity is not a major concern. However, the Russian V-agent, VR, contains a larger O-isobutyl, methylphosphonate center, making stereoselectivity a significant issue since the SP-enantiomer is expected to be significantly more toxic than the RP-enantiomer. The three-dimensional structure of the L7ep-3a variant was determined to a resolution of 2.01 Å (PDB id: 4ZST ). The active site of the L7ep-3a mutant has revealed a network of hydrogen bonding interactions between Asp-301, Tyr-257, Gln-254, and the hydroxide that bridges the two metal ions. A series of new analogues that mimic VX and VR has helped to identify critical structural features for the development of new enzyme variants that are further enhanced for the catalytic detoxification of VR and VX. The best of these mutants has been shown to have a reversed stereochemical preference for the hydrolysis of VR-chiral center analogues. This mutant hydrolyzes the two enantiomers of VR 160- and 600-fold faster than wild-type PTE hydrolyzes the SP-enantiomer of VR.

  8. The Fe-Cu Metastable Nano-scale Compound for Enhanced Absorption in the UV-Vis and NIR Ranges

    NASA Astrophysics Data System (ADS)

    Alami, Abdul Hai; Abed, Jehad; Almheiri, Meera; Alketbi, Afra

    2015-12-01

    This paper investigates the synthesis, microstructural characterization, electrical and optical, and thermal testing of Fe-Cu metastable alloy system for selective solar absorption applications. The system is produced by mechanical alloying using high-energy ball milling while monitoring its crystallographic morphology via X-ray diffraction from the initial as-is mixture up to the one produced after 8 hours milling time. The resulting homogeneous, metastable microstructure is examined by scanning electron microscopy and energy dispersive X-ray spectroscopy to verify the sought result of efficient inter-diffusion of elements. Optical spectroscopy results exhibit up to 81 pct enhanced absorption in the UV-Vis-NIR wavelength range with increased milling time from the as-is compound to the one obtained after 8 hours, while the trends of absorptivity curves had clear correlations with microstructural evolution. The impedance measurement of the resulting compound shows an increase in the resistance up to 120 Ω, compared with zero for the as-is starting mixture, which is a useful observation for many applications.

  9. Using simple agent-based modeling to inform and enhance neighborhood walkability

    PubMed Central

    2013-01-01

    modeling of different walking speeds and wait time at intersections. Conclusions The tool has the capacity to influence planning and public health advocacy and practice, and by using open-access source software, it is available for use locally and internationally. There is also scope to extend this version of the tool from a simple to a complex model, which includes agents (i.e., simulated pedestrians) ‘learning’ and incorporating other environmental attributes that enhance walkability (e.g., residential density, mixed land use, traffic volume). PMID:24330721

  10. Targeting SVCT for enhanced drug absorption: Synthesis and in vitro evaluation of a novel vitamin C conjugated prodrug of saquinavir

    PubMed Central

    Luo, Shuanghui; Wang, Zhiying; Patel, Mitesh; Khurana, Varun; Zhu, Xiaodong; Pal, Dhananjay; Mitra, Ashim. K.

    2015-01-01

    In order to improve oral absorption, a novel prodrug of saquinavir (Saq), ascorbyl-succinic-saquinavir (AA-Su-Saq) targeting sodium dependent vitamin C transporter (SVCT) was synthesized and evaluated. Aqueous solubility, stability and cytotoxicity were determined. Affinity of AA-Su-Saq towards effluxpump P-glycoprotein (P-gp) and recognition of AA-Su-Saq by SVCT were studied. Transepithelial permeability across polarized MDCK-MDR1 and Caco-2 cells were determined. Metabolic stability of AA-Su-Saq in rat liver microsomes was investigated. AA-Su-Saq appears to be fairly stable in both DPBS and Caco-2 cells with half lives of 9.65 and 5.73 h, respectively. Uptake of [3H]Saquinavir accelerated by 2.7 and 1.9 fold in the presence of 50 μM Saq and AA-Su-Saq in MDCK-MDR1 cells. Cellular accumulation of [14C]AA diminished by about 50–70% relative to control in the presence of 200 μM AA-Su-Saq in MDCK-MDR1 and Caco-2 cells. Uptake of AA-Su-Saq was lowered by 27% and 34% in the presence of 5 mM AA in MDCK-MDR1 and Caco-2 cells, respectively. Absorptive permeability of AA-Su-Saq was elevated about 4-5 fold and efflux index reduced by about 13-15 fold across the polarized MDCK-MDR1 and Caco-2 cells. Absorptive permeability of AA-Su-Saq decreased 44% in the presence of 5 mM AA across MDCK-MDR1 cells. AA-Su-Saq was devoid of cytotoxicity over the concentration range studied. AA-Su-Saq significantly enhanced the metabolic stability but lowered the affinity towards CYP3A4. In conclusion, prodrug modification of Saq through conjugation to AA via a linker significantly raised the absorptive permeability and metabolic stability. Such modification also caused significant evading of P-gp mediated efflux and CYP3A4 mediated metabolism. SVCT targeted prodrug approach can be an attractive strategy to enhance the oral absorption and systemic bioavailability of anti-HIV protease inhibitors. PMID:21571053

  11. Nanostructuring for enhanced absorption and carrier collection in CZTS-based solar cells: Coupled optical and electrical modeling

    NASA Astrophysics Data System (ADS)

    Abdelraouf, Omar A. M.; Allam, Nageh K.

    2016-04-01

    Earth-abundant Cu2ZnSnS4 (CZTS) is being considered as a potential photon-absorbing layer for low cost thin film solar cells. Nanostructured light trapping is recently investigated as a technique for enhancing the efficiency of CZTS solar cells. Herein, we used coupled electrical and optical modeling for different combinations of nanostructured CZTS solar cells to guide optimization of such nanostructures. The model is validated by a comparison of simulated I-V curves with previously reported experimental data. A very good agreement is achieved. Simulations are used to demonstrate that nanostructures can be tailored to maximize the absorption, carrier generation, carrier collection, and efficiency in CZTS solar cells. All proposed nanostructured solar cells showed enhancement in the overall conversion efficiency.

  12. Efficient optical absorption enhancement in organic solar cells by using a 2-dimensional periodic light trapping structure

    SciTech Connect

    Zu, Feng-Shuo; Shi, Xiao-Bo; Liang, Jian; Xu, Mei-Feng; Wang, Zhao-Kui E-mail: zkwang@suda.edu.cn Liao, Liang-Sheng E-mail: zkwang@suda.edu.cn; Lee, Chun-Sing E-mail: zkwang@suda.edu.cn

    2014-06-16

    We have investigated the effects induced by periodic nanosphere arrays on the performance of organic solar cells (OSCs). Two-dimensional periodic arrays of polystyrene nanospheres were formed by using a colloidal lithography method together with plasma etching to trim down the size to various degrees on the substrates of OSCs. It is found that the devices prepared on such substrates can have improved light harvesting, resulting in as high as 35% enhancement in power conversion efficiency over that of the reference devices. The measured external quantum efficiency and finite-difference time-domain simulation reveal that the controlled periodic morphology of the substrate can efficiently increase light scattering in the device and thus enhance the absorption of incident light.

  13. Interaction between indium tin oxide nanoparticles and cytochrome c: A surface-enhanced Raman scattering and absorption spectroscopic study

    SciTech Connect

    Yang, Yimin E-mail: tqiu@seu.edu.cn; Du, Deyang; Fan, Jiyang; Qiu, Teng E-mail: tqiu@seu.edu.cn; Kong, Fan

    2015-06-28

    Indium-tin-oxide (ITO) nanoparticles were annealed in vacuum or reducing atmosphere to obtain different surface structures and investigate their influence on the adsorptive character and conformation of cytochrome c (Cyt c) molecule. Annealing-induced morphometric or structural changes of ITO nanoparticles were characterized by instruments of transmission electron microscopy, x-ray diffraction, and Raman scattering. Semiconductor ITO nanoparticle-enhanced Raman scattering of Cyt c was observed and the enhanced efficiency was found to closely depend on the surface structures which control the adsorbance of buffer anions needed for Cyt c loading. Direct electron transfer between Cyt c and ITO surface at the moment of molecular elastic collision was found and a reverse electron transfer process for O-terminated surface and metal-terminated surface was observed, according to absorption spectroscopic measurement on the residual solution.

  14. Enhancement of specific absorption rate in lossy dielectric objects using a slab of left-handed material

    NASA Astrophysics Data System (ADS)

    Zhao, Lei; Cui, Tie Jun

    2005-12-01

    An enhancement of the specific absorption rate (SAR) inside a lossy dielectric object has been investigated theoretically based on a slab of left-handed medium (LHM). In order to make an accurate analysis of SAR distribution, a proper Green’s function involved in the LHM slab is proposed, from which an integral equation for the electric field inside the dielectric object is derived. Such an integral equation has been solved accurately and efficiently using the conjugate gradient method and the fast Fourier transform. We have made a lot of numerical experiments on the SAR distributions inside the dielectric object excited by a line source with and without the LHM slab. Numerical experiments show that SAR can be enhanced tremendously when the LHM slab is involved due to the proper usage of strong surface waves, which will be helpful in the potential biomedical applications for hyperthermia. The physical insight for such a phenomenon has also been discussed.

  15. Efficacy of Flaxseed Flour as Bind Enhancing Agent on the Quality of Extended Restructured Mutton Chops

    PubMed Central

    Sharma, Heena; Sharma, Brahma Deo; Mendiratta, S. K.; Talukder, Suman; Ramasamy, Giriprasad

    2014-01-01

    Consumers have become very conscious about their nutrition and well being due to changes in their socio-economic lifestyle and rapid urbanization. Therefore, development of technology for production of low cost and functional meat products is urgently required. One such approach is innovative restructuring technology in which binding of meat pieces still remains the main challenge and extension of product is generally associated with poor binding and texture. Thus, the present study was envisaged as an attempt to solve this problem by the incorporation of flaxseed flour (FF) as bind enhancing agent. The FF was used at three different levels viz., 0.5%, 1%, and 1.5% to replace lean meat in pre-standardized restructured mutton chops formulation. The products were subjected to analysis for physico-chemical, sensory and textural properties. Cooking yield, moisture percentage and fat percentage increased with increase in the level of incorporation of FF, however, protein percent and pH decreased with increase in the level of incorporation. Shear force value of product incorporated with 1.5% FF was significantly higher (p<0.01) than control and product containing 0.5% FF level. Among the sensory attributes, product with 1% flaxseed flour showed significantly higher values (p<0.05) for general appearance, binding, texture and overall acceptability. Hardness showed significant increasing (p<0.01) values with increasing levels of incorporation of flaxseed flour, however all other parameters of texture profile analysis showed a decreasing trend. On the basis of sensory scores and physico-chemical properties, the optimum incorporation level of FF was adjudged as 1%. Products incorporated with optimum level of flaxseed flour (1%) were also assessed for water activity and microbiological quality during the storage period of 15 days. It was found that the extended restructured product could be safely stored under refrigeration (4°C±1°C) in low density polyethylene (LDPE

  16. Carbonic anhydrase mimics for enhanced CO2 absorption in an amine-based capture solvent.

    PubMed

    Kelsey, Rachael A; Miller, David A; Parkin, Sean R; Liu, Kun; Remias, Joe E; Yang, Yue; Lightstone, Felice C; Liu, Kunlei; Lippert, Cameron A; Odom, Susan A

    2016-01-07

    Two new small-molecule enzyme mimics of carbonic anhydrase were prepared and characterized. These complexes contain the salen-like ligand bis(hydroxyphenyl)phenanthroline. This ligand is similar to the salen-type ligands previously incorporated into carbonic anhydrase mimics but contains no hydrolyzable imine groups and therefore serves as a promising ligand scaffold for the synthesis of a more robust CO2 hydration catalyst. These homogeneous catalysts were investigated for CO2 hydration in concentrated primary amine solutions through which a dilute CO2 (14%) fluid stream was flowed and showed exceptional activity for increased CO2 absorption rates.

  17. Enhanced Microwave Absorption Performance of Coated Carbon Nanotubes by Optimizing the Fe3O4 Nanocoating Structure.

    PubMed

    Li, Na; Huang, Gui-Wen; Li, Yuan-Qing; Xiao, Hong-Mei; Feng, Qing-Ping; Hu, Ning; Fu, Shao-Yun

    2017-01-25

    It is well accepted that the microwave absorption performance (MAP) of carbon nanotubes (CNTs) can be enhanced via coating magnetic nanoparticles on their surfaces. However, it is still unclear if the magnetic coating structure has a significant influence on the microwave absorption behavior. In this work, nano-Fe3O4 compact-coated CNTs (FCCs) and Fe3O4 loose-coated CNTs (FLCs) are prepared using a simple solvothermal method. The MAP of the Fe3O4-coated CNTs is shown to be adjustable via controlling the Fe3O4 nanocoating structure. The results reveal that the overall MAP of coated CNTs strongly depends on the magnetic coating structure. In addition, the FCCs show a much better MAP than the FLCs. It is shown that the microwave absorption difference between the FLCs and FCCs is due to the disparate complementarities between the dielectric loss and the magnetic loss, which are related to the coverage density of Fe3O4 nanoparticles on the surfaces of CNTs. For FCCs, the mass ratio of CNTs to Fe(3+) is then optimized to maximize the effective complementarities between the dielectric loss and the magnetic loss. Finally, a comparison is made with the literature on Fe3O4-carbon-based composites. The FCCs at the optimized CNT to Fe(3+) ratio in the present work show the most effective specific RLmin (28.7 dB·mm(-1)) and the widest effective bandwidth (RL < -10 dB) (8.3 GHz). The excellent MAP of the as-prepared FCC sample is demonstrated to result from the consequent dielectric relaxation process and the improved magnetic loss. Consequently, the structure-property relationship revealed is significant for the design and preparation of CNT-based materials with effective microwave absorption.

  18. Improvement in the photocurrent collection due to enhanced absorption of light by synthesizing staggered layers of silver nanoclusters in silicon

    SciTech Connect

    Dhoubhadel, Mangal S.; Lakshantha, Wickramaarachchige J.; Rout, Bibhudutta; McDaniel, Floyd D.; Lightbourne, Sherard; D’Souza, Francis

    2015-07-23

    The quest for increased efficiency of solar cells has driven the research in synthesizing photovoltaic cells involving Si based materials. The efficiency of solar cells involving crystalline Si is stalled around 25% for the last decade. Recently Shi et al. had shown that light trapping can be enhanced by fabricating double layers of Ag nanoparticles in silicon based materials. The light trapping is critically important in a photo devices such as solar cells in order to increase light absorption and efficiency. In the present work, we report enhancement in the absorption of light in Ag ion implanted Si substrates. Multiple low energies Ag ions, ranging from ∼80 keV to ∼30 keV, with different fluences ranging from ∼1 × 10{sup 16} to ∼1 × 10{sup 17} atoms/cm{sup 2} were sequentially implanted into commercially available Si (100) substrates followed by post-thermal annealing to create different sizes of Ag nanoclusters (NC) at different depths in the top 100 nm of the Si. The absorbance of light is increased in Ag implanted Si with a significant increase in the current collection in I-V (current-voltage) photo switching measurements. The experimental photovoltaic cells fabricated with the Ag-implanted Si samples were optically characterized under AM (air mass) 1.5 solar radiation conditions (∼1.0 kW/m{sup 2}). An enhancement in the charge collection were measured in the annealed samples, where prominent Ag NCs were formed in the Si matrix compared to the as-implanted samples with amorphous layers. We believe the enhancement of the photo-current density from the samples with Ag NC is due to the improvement of efficiency of charge collection of e{sup −}-h{sup +} pairs produced by the incident light.

  19. Broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Zarzana, K. J.; Rudich, Y.; Brown, S. S.

    2016-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and it strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99930 ± 0.00003 (1- reflectivity = 700 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.43 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity-enhanced absorption spectroscopy and cavity ring-down spectroscopy agree within 2 % (slope for linear fit = 1.02 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity-enhanced absorption spectroscopy and calculated based on flow dilution are also well correlated, with r2 = 0.9998. During constant mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1 min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically based trace gas detection that may complement higher precision techniques based on non

  20. Plasmon-Enhanced Light Absorption in GaAs Nanowire Array Solar Cells.

    PubMed

    Li, Yanhong; Yan, Xin; Wu, Yao; Zhang, Xia; Ren, Xiaomin

    2015-12-01

    In this paper, we propose a plasmon-enhanced solar cell structure based on a GaAs nanowire array decorated with metal nanoparticles. The results show that by engineering the metallic nanoparticles, localized surface plasmon could be excited, which can concentrate the incident light and propagate the energy to nanowires. The surface plasmon can dramatically enhance the absorbance of near-bandgap light, and the enhancement is influenced by the size and material of nanoparticles. By optimizing the particle parameters, a large absorbance enhancement of 50 % at 760 nm and a high conversion efficiency of 14.5 % can be obtained at a low diameter and period ratio (D/P ratio) of 0.3. The structure is promising for low-cost high-performance nanoscale solar cells.

  1. Plasmon-Enhanced Light Absorption in GaAs Nanowire Array Solar Cells

    NASA Astrophysics Data System (ADS)

    Li, Yanhong; Yan, Xin; Wu, Yao; Zhang, Xia; Ren, Xiaomin

    2015-11-01

    In this paper, we propose a plasmon-enhanced solar cell structure based on a GaAs nanowire array decorated with metal nanoparticles. The results show that by engineering the metallic nanoparticles, localized surface plasmon could be excited, which can concentrate the incident light and propagate the energy to nanowires. The surface plasmon can dramatically enhance the absorbance of near-bandgap light, and the enhancement is influenced by the size and material of nanoparticles. By optimizing the particle parameters, a large absorbance enhancement of 50 % at 760 nm and a high conversion efficiency of 14.5 % can be obtained at a low diameter and period ratio ( D/ P ratio) of 0.3. The structure is promising for low-cost high-performance nanoscale solar cells.

  2. Enhanced frequency response in monolithically integrated coupled cavity lasers and electro-absorption modulator.

    SciTech Connect

    Wendt, Joel Robert; Vawter, Gregory Allen; Tauke-Pedretti, Anna; Alford, Charles Fred; Skogen, Erik J.; Chow, Weng Wah; Overberg, Mark E.; Torres, David L.; Yang, Zhenshan; Peake, Gregory Merwin

    2010-11-01

    We present the bandwidth enhancement of an EAM monolithically integrated with two mutually injection-locked lasers. An improvement in the modulation efficiency and bandwidth are shown with mutual injection locking.

  3. Numerical calculation of visible light absorption enhancement of CdSe-quantum dot-sensitized TiO2 nanorod periodic array as photoanode

    NASA Astrophysics Data System (ADS)

    Kohnehpoushi, Saman; Eskandari, Mehdi; Abdollahi Nejand, Bahram; Ahmadi, Vahid

    2017-02-01

    Light absorption enhancement in a CdSe-quantum dot (QD)-sensitized TiO2 nanorod periodic array-based photoanode is calculated by the finite differential time domain (FDTD) model through optimizing the height, diameter, and periodic space between TiO2 nanorods. Results show that light absorption in the CdSe-QD-sensitized TiO2 nanorods is enhanced at the visible wavelength range and the absorption edge is shifted toward higher wavelengths as a result of decreasing the height and increasing the diameter of the TiO2 nanorods. Consequently, the equivalent bandgap of the CdSe-QD-sensitized TiO2 nanorod photoanode was decreased. Also, absorption spectra indicate that the position of the absorption peak related to TiO2 has a redshift with increasing periodic space between the TiO2 nanorods, suggesting a decrease in the bandgap of TiO2. In addition, results show that for TiO2 nanorod heights lower than 300 nm, light absorption in the visible region is considerably enhanced as the periodic space is reduced from 400 nm to 100 nm. In comparison, for TiO2 nanorod heights larger than 300 nm, light absorption is considerably enhanced. Finally, it is found from absorption spectra that coupling optical modes of TiO2 nanorods and CdSe QDs are enhanced by increasing the diameter and decreasing the height and periodic space between the TiO2 nanorods. As a result, the light absorption is increased in the photoanodes at the visible region, leading to an improvement in the performance of the photoanode at visible light.

  4. Incoherent broad-band cavity-enhanced absorption spectroscopy of the marine boundary layer species I2, IO and OIO.

    PubMed

    Vaughan, Stewart; Gherman, Titus; Ruth, Albert A; Orphal, Johannes

    2008-08-14

    The novel combination of incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS) and a discharge-flow tube for the study of three key atmospheric trace species, I(2), IO and OIO, is reported. Absorption measurements of I(2) and OIO at lambda=525-555 nm and IO at lambda=420-460 nm were made using a compact cavity-enhanced spectrometer employing a 150 W short-arc Xenon lamp. The use of a flow system allowed the monitoring of the chemically short-lived radical species IO and OIO to be conducted over timescales of several seconds. We report detection limits of approximately 26 pmol mol(-1) for I(2) (L=81 cm, acquisition time 60 s), approximately 45 pmol mol(-1) for OIO (L=42.5 cm, acquisition time 5 s) and approximately 210 pmol mol(-1) for IO (L=70 cm, acquisition time 60 s), demonstrating the usefulness of this approach for monitoring these important species in both laboratory studies and field campaigns.

  5. Enhancement mechanism of the additional absorbent on the absorption of the absorbing composite using a type-based mixing rule

    NASA Astrophysics Data System (ADS)

    Xu, Yonggang; Yuan, Liming; Zhang, Deyuan

    2016-04-01

    A silicone rubber composite filled with carbonyl iron particles and four different carbonous materials (carbon black, graphite, carbon fiber or multi-walled carbon nanotubes) was prepared using a two-roller mixture. The complex permittivity and permeability were measured using a vector network analyzer at the frequency of 2-18 GHz. Then a type-based mixing rule based on the dielectric absorbent and magnetic absorbent was proposed to reveal the enhancing mechanism on the permittivity and permeability. The enforcement effect lies in the decreased percolation threshold and the changing pending parameter as the carbonous materials were added. The reflection loss (RL) result showed the added carbonous materials enhanced the absorption in the lower frequency range, the RL decrement value being about 2 dB at 4-5 GHz with a thickness of 1 mm. All the added carbonous materials reinforced the shielding effectiveness (SE) of the composites. The maximum increment value of the SE was about 3.23 dB at 0.5 mm and 4.65 dB at 1 mm, respectively. The added carbonous materials could be effective additives for enforcing the absorption and shielding property of the absorbers.

  6. Tetradecylmaltoside (TDM) enhances in vitro and in vivo intestinal absorption of enoxaparin, a low molecular weight heparin.

    PubMed

    Yang, Tianzhi; Arnold, John J; Ahsan, Fakhrul

    2005-01-01

    Tetradecylmaltoside (TDM) was evaluated as a potential gastrointestinal absorption enhancer for low molecular weight heparin (LMWH), enoxaparin. The in vitro efficacy of TDM (0.0625, 0.125 and 0.25% w/v) in enhancing transport of 3H-enoxaparin or 14C-mannitol was investigated in human colonic epithelial cells (C2BBel). Metabolic stability of the drug was determined in C2BBel cell extracts. Transepithelial electrical resistance (TEER) was measured before and after exposure of the cells to TDM. Enoxaparin was further administered to anesthetized Sprague-Dawley rats in oral formulations in the absence or presence of increasing concentrations of TDM and drug absorption was monitored by measuring anti-factor Xa activity in rat blood. In vitro permeability study shows that apparent permeability (Papp) of 3H-enoxaparin across C2BBe1 cells was increased by 8-fold in the presence of 0.0625% TDM compared to untreated cells. The movement of 14C-mannitol across the cell monolayer followed a similar pattern in the presence of increasing concentrations of TDM. No degradation or depolymerization of enoxaparin was observed when the drug was incubated in C2BBel cell extract. TEER was reversible after 60 min exposure of the cells to 0.0625% (w/v) TDM. Oral formulations of enoxaparin containing TDM administered to anesthetized rats significantly and rapidly increased gastrointestinal absorption as compared to those animals which received enoxaparin plus saline (p < 0.05). In the presence of 0.125% TDM in the formulation, enoxaparin oral bioavailability was increased by 2.5-fold compared to the saline control group. Overall, the data on the effect of TDM on the in vitro and in vivo intestinal permeation of enoxaparin suggest that TDM may represent a promising excipient for use in oral LMWH formulations.

  7. Enhanced nonlinear optical absorption and optical limiting properties of superparamagnetic spinel zinc ferrite decorated reduced graphene oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Saravanan, M.; T. C., Sabari Girisun

    2017-01-01

    Nonlinear absorption and optical limiting properties of ZnFe2O4-rGO magnetic nanostructures was investigated by the Z-scan technique using Q-switched Nd:YAG laser (5 ns, 532 nm, 10 Hz) as an excitation source. Excited state absorption was the dominant process responsible for the observed nonlinearity in ZnFe2O4 decorated rGO which arises due to photo-generated charge carriers in the conduction band of zinc ferrite and increases in defects at the surface of rGO due to the incorporation of ZnFe2O4. The magnitude of the nonlinear absorption co-efficient was found to be in the order of 10-10 m/W. A noteworthy enhancement in the third-order NLO properties in ZnFe2O4-(15 wt%) rGO with those of individual counter parts and well known graphene composites was reported. Role of induced defects states (sp3) arising from the functionalization of rGO in the enhancement of NLO response was explained through Raman studies. Earlier incorporation and distribution of ZnFe2O4 upon GO through one-step hydrothermal method was analyzed by XRD and FTIR. Formation of (nanospheres/nanospindles) ZnFe2O4 along with reduction of graphene oxide was confirmed through TEM analysis. VSM studies showed zinc ferrite decorated rGO posseses superparamagnetic behavior. The tuning of nonlinear optical and magnetic behavior with variation in the content of spinel ferrites upon reduced graphene oxide provides an easy way to attain tunable properties which are exceedingly required in both optoelectronics and photothermal therapy applications.

  8. Enhancement of contamination growth and damage by absorption centers under UV irradiation

    NASA Astrophysics Data System (ADS)

    Balasa, I.; Hippler, M.; Schröder, H.; Jensen, L.; Gauch, M.; Ristau, D.; Riede, W.

    2014-11-01

    Contamination plays a major role in lifetime of vacuum optics. Several efforts have been made to derive suitable models for lifetime prediction in laser-induced contamination related optical breakdown. But the broad spectrum of potential contaminants present in the various applications with their very specific contamination mechanisms complicates the derivation of universal optics degradation models. As one possible contamination initiation process, the impact of optical absorption on the laser-induced contamination and resulting optical breakdown is studied in this work. A set of specifically prepared samples using nanometer sized gold particles embedded in dense IBS anti-reflecting coatings is exposed to radiation of 355nm in low pressure naphthalene atmosphere. Even though the artificial defects are not in direct contact with the contaminant, their influence on the long-term optics performance in dependence on the particle concentration in the coating is evident. In the presence of naphthalene, the artificial nano-defects cause a significantly accelerated degradation compared to reference samples without those defects or in absence of the contaminant. For this specific type of contaminant, a correlation of the optical absorption and long-term durability is derived.

  9. Structural differences of prebiotic oligosaccharides influence their capability to enhance iron absorption in deficient rats.

    PubMed

    Laparra, José Moisés; Díez-Municio, Marina; Herrero, Miguel; Moreno, F Javier

    2014-10-01

    This study evaluates the influence of novel galacto-oligosaccharides derived from lactulose (GOS-Lu), kojibiose or 4'-galactosyl-kojibiose in hematological parameters of Fe homeostasis using Fe-deficient animals. Liver TfR-2, IL-6, NFκB and PPAR-γ expression (mRNA) were also determined by RT-qPCR analyses, and active hepcidin peptide production and short chain fatty acids by LC coupled to MS/MS or UV detection. Feeding animals with GOS-Lu or kojibiose together with FeCl3 increased hemoglobin (Hb) production (by 17%) and mean Hb concentration into erythrocytes relative to animals administered with FeCl3 alone (14.1% and 19.7%, respectively). Animals administered with prebiotics showed decreased plasmatic hepcidin levels, contributing to a higher intestinal absorption of the micronutrient. These data indicate that concurrent administration of these potentially prebiotic oligosaccharides together with a supplement of Fe ameliorates inflammation-mediated perturbations in the liver, according to the particular structure of the prebiotic compound, and result an attractive strategy to improve Fe absorption.

  10. 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

    2016-03-09

    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.

  11. Synthesis and significantly enhanced microwave absorption properties of hematite dendrites/polyaniline nanocomposite

    NASA Astrophysics Data System (ADS)

    Wu, Hao; Wang, Liuding; Wu, Hongjing; Lian, Qian

    2014-06-01

    Hematite dendrites/polyaniline (HDs/PANI) nanocomposite, i.e. coating HDs with conductive PANI, has been successfully synthesized through a two-step polymerization of aniline monomers on the surface of pre-synthesized HDs for the first time. It is discovered that a lower concentration of HCl (0.02 mol L-1) has only a slight adverse effect on the dendritic structures of the coated HDs, while a higher concentration of HCl (0.04 mol L-1) results in severe damage to the sub-branches of the HDs. The morphology, composition, structure, static magnetic, and spectral properties of the as-prepared pristine HDs and HDs/PANI composites were thoroughly characterized by various physicochemical techniques. Moreover, the electromagnetic and microwave absorbing properties of the HDs and HDs/PANI wax composites were compared in detail. It was found that the frequency of absorption obeys a quarter-wavelength model for both of them, and the HDs/PANI wax composite exhibits far superior microwave absorption properties. This phenomenon can be attributed to the improved dielectric loss abilities and the complementary behaviors resulting from the PANI coatings and fractal-structured HDs.

  12. Simulations of enhanced absorption in composite embedded, insulated metal nanopatterns for ultrathin film photovoltaics

    NASA Astrophysics Data System (ADS)

    Liu, Xinyu; Ye, Fan; Burns, Michael J.; Naughton, Michael J.

    2012-02-01

    In recent work [1], a concept of employing embedded metallic nanopatterns (EMN) in ultrathin film solar cells was discussed. Elsewhere in this conference, Fan et al. advance this with a scheme for embedded insulated metallic nanopatterns (EIMN) that is designed to avoid deleterious carrier recombination as would result from bare metal inclusions in a PV film. However, a practical route to fabricating EIMNs of desired shapes for eventual scale production is nontrivial. Here, we introduce two notions toward that goal, nano-stamping and spin-coating, of compact arrays of metallic core/insulating shell nanoparticles (MNP). We show by simulations that optical absorption of an EIMN composed of arrays of core-shell MNPs having SiO2 coatings is essentially the same as that of an EMN composed of solid metals without insulation, with absorption concentrated in the surrounding PV medium. These concepts may provide practical routes for scalability of EIMN-based ultrathin film plasmonic solar cells.[4pt] [1] F. Ye, M. J. Burns, M. J. Naughton, Proc. SPIE 8111, 811103 (2011), and this conference.

  13. The determination of wear metals in used lubricating oils by flame atomic absorption spectrometry using sulphanilic acid as ashing agent.

    PubMed

    Ekanem, E J; Lori, J A; Thomas, S A

    1997-11-01

    A simple and reliable ashing procedure is proposed for the preparation of used lubricating oil samples for the determination of calcium, magnesium, zinc, iron, chromium and nickel by flame atomic absorption spectrometry. Sulphanilic acid was added to oil samples and the mixture coked and the coke ashed at 550 degrees C. The solutions of the ash were analysed by flame AAS for the metals. The release of calcium, zinc, iron and chromium was improved by the addition of sulphanilic acid to samples. The relative standard deviations of metal concentration results in the initial oil samples were 1.5% for Ca (1500 mg l(-1) level), 0.3% for Mg (100 mg l(-1) level), 3.1% for Zn (1500 mg l(-1) level), 0.7% for Fe (500 mg l(-1) level), 0.02% for Cr (50 mg l(-1) level) and 0.002% for Ni (10 mg l(-1) level). The optimum sample size for efficient metal release was 20 g while the optimum sulphanilic acid to oil ratio was 0.05 g per gram of oil for Zn and Cr and 0.10 g for Ca and Fe. Results obtained by this procedure were highly reproducible and comparable with those obtained for the same samples using standard procedures.

  14. Treatment Strategies that Enhance the Efficacy and Selectivity of Mitochondria-Targeted Anticancer Agents

    PubMed Central

    Modica-Napolitano, Josephine S.; Weissig, Volkmar

    2015-01-01

    Nearly a century has passed since Otto Warburg first observed high rates of aerobic glycolysis in a variety of tumor cell types and suggested that this phenomenon might be due to an impaired mitochondrial respiratory capacity in these cells. Subsequently, much has been written about the role of mitochondria in the initiation and/or progression of various forms of cancer, and the possibility of exploiting differences in mitochondrial structure and function between normal and malignant cells as targets for cancer chemotherapy. A number of mitochondria-targeted compounds have shown efficacy in selective cancer cell killing in pre-clinical and early clinical testing, including those that induce mitochondria permeability transition and apoptosis, metabolic inhibitors, and ROS regulators. To date, however, none has exhibited the standards for high selectivity and efficacy and low toxicity necessary to progress beyond phase III clinical trials and be used as a viable, single modality treatment option for human cancers. This review explores alternative treatment strategies that have been shown to enhance the efficacy and selectivity of mitochondria-targeted anticancer agents in vitro and in vivo, and may yet fulfill the clinical promise of exploiting the mitochondrion as a target for cancer chemotherapy. PMID:26230693

  15. Adsorption of a dye on clay and sand. Use of cyclodextrins as solubility-enhancement agents.

    PubMed

    De Lisi, Rosario; Lazzara, Giuseppe; Milioto, Stefania; Muratore, Nicola

    2007-11-01

    Laboratory-scale studies were aimed at elucidating the physico-chemical aspects on the removal process of crystal violet (CV) from waters and solid substrates. The laponite clay (RD) and sand were chosen for the double aim at investigating them as CV adsorbents for water treatment and as substrates which mime the soil components. Sand is very effective in removing CV from waters. The cyclodextrins (CDs) were exploited as solubility-enhancement agents to remove CV from the solid substrates. They are powerful solvent media because they extract the CV from sand forming water-soluble CV/CD inclusion complexes and do not show affinity for sand. Optimum performance was shown by the modified CDs (i.e. hydroxypropyl-beta-cyclodextrin and methyl-beta-cyclodextrin). A linear correlation between the logarithm of the equilibrium constant for the CV/CD inclusion complexes formation (K(cpx)) and the maximum amount of CV extracted from sand in the columns experiments at a flow rate of 1.5 ml min(-1) was drawn. This relationship predicts that CDs with K(cpx)<180 M(-1) are not suitable for CV removal from sand. CDs failed to displace CV from RD because they generate the formation of RD clusters where CV remains entrapped.

  16. Comparison of different chelating agents to enhance reductive Cr(VI) removal by pyrite treatment procedure.

    PubMed

    Kantar, Cetin; Ari, Cihan; Keskin, Selda

    2015-06-01

    New technologies involving in-situ chemical hexavalent chromium [Cr(VI)] reduction to trivalent chromium [Cr(III)] with natural Fe(II)-containing minerals can offer viable solutions to the treatment of wastewater and subsurface systems contaminated with Cr(VI). Here, the effects of five different chelating agents including citrate, EDTA, oxalate, tartrate and salicylate on reductive Cr(VI) removal from aqueous systems by pyrite were investigated in batch reactors. The Cr(VI) removal was highly dependent on the type of ligand used and chemical conditions (e.g., ligand concentration). While salicylate and EDTA had no or little effect on Cr(VI) removal, the ligands including citrate, tartrate and oxalate significantly enhanced Cr(VI) removal at pH < 7 relative to non-ligand systems. In general, the efficiency of organic ligands on Cr(VI) removal decreased in the order: citrate ≥ oxalate ≈ tartrate > EDTA > salicylate ≈ non-ligand system. Organic ligands enhanced Cr(VI) removal by 1) removing surface oxide layer via the formation of soluble Fe-Cr-ligand complexes, and 2) enhancing the reductive iron redox cycling for the regeneration of new surface sites. While citrate, oxalate and tartrate eliminated the formation of surface Cr (III)-Fe(III)-oxides, the surface phase Cr (III) species was observed in the presence of EDTA and salicylate indicating that Cr(III) complexed with EDTA and salicylate sorbed or precipitated onto pyrite surface, thereby blocking the access of CrO4(2-) to pyrite surface. The binding of Fe(III) with the disulfide reactive sites (≡Fe-S-S-Fe(III)) was essential for the regeneration of new surface sites through pyrite oxidation. Although Fe(III)-S species was detected at the pyrite surface in the presence of citrate, oxalate and tartrate, Fe(III) complexed with EDTA and salicylate did not strongly interact with the disulfide reactive sites due to the formation of non-sorbing Fe(III)-ligand complexes. The absence of surface Fe

  17. Feshbach enhanced s-wave scattering of fermions: direct observation with optimized absorption imaging

    PubMed Central

    Genkina, D; Aycock, LM; Stuhl, BK; Lu, H-I; Williams, RA; Spielman, IB

    2016-01-01

    We directly measured the normalized s-wave scattering cross-section of ultracold 40K atoms across a magnetic-field Feshbach resonance by colliding pairs of degenerate Fermi gases (DFGs) and imaging the scattered atoms. We extracted the scattered fraction for a range of bias magnetic fields, and measured the resonance location to be B0 = 20.206(15) mT with width Δ = 1.0(5) mT. To optimize the signal-to-noise ratio of atom number in scattering images, we developed techniques to interpret absorption images in a regime where recoil induced detuning corrections are significant. These imaging techniques are generally applicable to experiments with lighter alkalis that would benefit from maximizing signal-to-noise ratio on atom number counting at the expense of spatial imaging resolution. PMID:26903778

  18. Surface plasmon enhanced absorption and suppressed transmission in periodic arrays of graphene ribbons

    NASA Astrophysics Data System (ADS)

    Nikitin, A. Yu.; Guinea, F.; Garcia-Vidal, F. J.; Martin-Moreno, L.

    2012-02-01

    Resonance diffraction in the periodic array of graphene microribbons is theoretically studied following a recent experiment [L. Ju , Nature Nanotech.1748-338710.1038/nnano.2011.146 6, 630 (2011)]. Systematic studies over a wide range of parameters are presented. It is shown that a much richer resonant picture would be observable for higher relaxation times of charge carriers: More resonances appear and transmission can be totally suppressed. The comparison with the absorption cross-section of a single ribbon shows that the resonant features of the periodic array are associated with leaky plasmonic modes. The longest-wavelength resonance provides the highest visibility of the transmission dip and has the strongest spectral shift and broadening with respect to the single-ribbon resonance, due to collective effects.

  19. The time-dependent emission of molecular iodine from Laminaria Digitata measured with incoherent broadband cavity-enhanced absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Dixneuf, S.

    2009-04-01

    The release of molecular iodine (I2) from the oceans into the atmosphere has been recognized to correlate strongly with ozone depletion events and aerosol formation in the Marine Boundary Layer (MBL), which affects in turn global radiative forcing. The detailed mechanisms and dominant sources leading to the observed concentrations of I2 in the marine troposphere are still under intense investigation. In a recent campaign on the Irish west coast at Mace Head Atmospheric Research Station [1], it was found that significant levels of molecular iodine correlated with times of low tide, suggesting that the emission of air-exposed macro-algae may be a prime source of molecular iodine in coastal areas [2]. To further investigate this hypothesis we tried to detect the I2 emission of the brown seaweed Laminaria digitata, one of the most efficient iodine accumulators among living systems, directly by means of highly sensitive incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) [3]. IBBCEAS combines a good temporal and spatial resolution with high molecule-specific detection limits [4] comparable to that of typical LP-DOAS. IBBCEAS thus complements LP-DOAS in the search for sources of tropospheric trace gases. In this presentation the first direct observation of the time dependence of molecular iodine emission from Laminaria digitata will be shown. Plants were studied under naturally occurring stress for quasi in situ conditions for many hours. Surprisingly, the release of I2 occurs in short, strong bursts with quasi-oscillatory behaviour, bearing similarities to well known "iodine clock reactions". References [1] Saiz-Lopez A. & Plane, J. M. C. Novel iodine chemistry in the marine boundary layer. Geophys. Res. Lett. 31, L04112 (2004) doi:10.1029/2003GL019215. [2] McFiggans, G., Coe, H., Burgess, R., Allan, J., Cubison, M., Alfarra, M. R., Saunders, R., Saiz-Lopez, A., Plane, J. M. C., Wevill, D. J., Carpenter, L. J., Rickard, A. R. & Monks, P. S. Direct

  20. Enhanced small intestinal absorption of beta-lactam antibiotics in rats in the presence of monodesmosides isolated from pericarps of Sapindus mukurossi (Enmei-hi).

    PubMed

    Yata, N; Sugihara, N; Yamajo, R; Murakami, T; Higashi, Y; Kimata, H; Nakayama, K; Kuzuki, T; Tanaka, O

    1986-02-01

    Monodesmoside, saponin A, B and C, isolated from pericarps of Sapindus mukurossi (Enmei-hi) have been shown to promote absorption of poorly absorbed beta-lactam antibiotics by the small intestine using an in situ loop method. Monodesmosides were solubilized with ginseng crude saponin extract, a mixture of bisdesmosides, saponin X, Y1 and Y2 which were isolated also from Sapindus mukurossi. These solubilizing agents were demonstrated not to influence the absorption promoting effect of monodesmosides. Among the monodesmosides, saponin B showed the greatest effect. No influence of osmolarity of the administered solution on the absorption promoting action was observed. The promoting functions of the three monodesmosides for the small intestinal absorption of antibiotics were suppressed by Ca2+ ion coexisting in the administered solution.

  1. Liver-specific agents for contrast-enhanced MRI: role in oncological imaging

    PubMed Central

    Thian, Yee Liang; Riddell, Angela M.

    2013-01-01

    Abstract Liver-specific magnetic resonance (MR) contrast agents are increasingly used in evaluation of the liver. They are effective in detection and morphological characterization of lesions, and can be useful for evaluation of biliary tree anatomy and liver function. The typical appearances and imaging pitfalls of various tumours at MR imaging performed with these agents can be understood by the interplay of pharmacokinetics of these contrast agents and transporter expression of the tumour. This review focuses on the applications of these agents in oncological imaging. PMID:24434892

  2. Luminal glucose does not enhance active intestinal calcium absorption in mice: evidence against a role for Ca(v)1.3 as a mediator of calcium uptake during absorption.

    PubMed

    Reyes-Fernandez, Perla C; Fleet, James C

    2015-11-01

    Intestinal Ca absorption occurs through a 1,25-dihydroxyvitamin D3 (1,25(OH)2D3)-regulated transcellular pathway, especially when habitual dietary Ca intake is low. Recently the L-type voltage-gated Ca channel, Cav1.3, was proposed to mediate active, transcellular Ca absorption in response to membrane depolarization caused by elevated luminal glucose levels after a meal. We tested the hypothesis that high luminal glucose could reveal a role for Cav1.3 in active intestinal Ca absorption in mice. Nine-week-old male C57BL/6 J mice were fed AIN93G diets containing either low (0.125%) or high (1%) Ca for 1 week, and Ca absorption was examined by an oral gavage method using a 45Ca-transport buffer containing 25 mmol/L of glucose or fructose. Transient receptor potential vanilloid 6 (TRPV6), calbindin D9k (CaBPD9k), and Cav1.3 messenger RNA (mRNA) levels were measured in the duodenum, jejunum, and ileum. TRPV6 and CaBPD9k expressions were highest in the duodenum, where active, 1,25(OH)2D3-regulated Ca absorption occurs, whereas Cav1.3 mRNA levels were similar across the intestinal segments. As expected, the low-Ca diet increased renal cytochrome p450-27B1 (CYP27B1) mRNA (P = .003), serum 1,25(OH)2D3 (P < .001), and Ca absorption efficiency by 2-fold with the fructose buffer. However, the glucose buffer used to favor Cav1.3 activation did not increase Ca absorption efficiency (P = .6) regardless of the dietary Ca intake level. Collectively, our results show that glucose did not enhance Ca absorption and they do not support a critical role for Cav1.3 in either basal or vitamin D-regulated intestinal Ca absorption in vivo.

  3. A shape memory foam composite with enhanced fluid uptake and bactericidal properties as a hemostatic agent.

    PubMed

    Landsman, T L; Touchet, T; Hasan, S M; Smith, C; Russell, B; Rivera, J; Maitland, D J; Cosgriff-Hernandez, E

    2017-01-01

    Uncontrolled hemorrhage accounts for more than 30% of trauma deaths worldwide. Current hemostatic devices focus primarily on time to hemostasis, but prevention of bacterial infection is also critical for improving survival rates. In this study, we sought to improve on current devices used for hemorrhage control by combining the large volume-filling capabilities and rapid clotting of shape memory polymer (SMP) foams with the swelling capacity of hydrogels. In addition, a hydrogel composition was selected that readily complexes with elemental iodine to impart bactericidal properties to the device. The focus of this work was to verify that the advantages of each respective material (SMP foam and hydrogel) are retained when combined in a composite device. The iodine-doped hydrogel demonstrated an 80% reduction in bacteria viability when cultured with a high bioburden of Staphylococcus aureus. Hydrogel coating of the SMP foam increased fluid uptake by 19× over the uncoated SMP foam. The composite device retained the shape memory behavior of the foam with more than 15× volume expansion after being submerged in 37°C water for 15 min. Finally, the expansion force of the composite was tested to assess potential tissue damage within the wound during device expansion. Expansion forces did not exceed 0.6N, making tissue damage during device expansion unlikely, even when the expanded device diameter is substantially larger than the target wound site. Overall, the enhanced fluid uptake and bactericidal properties of the shape memory foam composite indicate its strong potential as a hemostatic agent to treat non-compressible wounds.

  4. Enhanced Thermal Ablation by Combining Ultrasound Contrast Agents with a Miniature Flat Transducer

    NASA Astrophysics Data System (ADS)

    Murillo, A.; Goldendstedt, C.; Lafon, C.; Cathignol, D.; Chapelon, J.-Y.

    2007-05-01

    Miniature transducers can be used for performing interstitial thermal ablation. Increasing the frequency of non-focused transducers enhances energy deposition but limits the therapeutic range. In order to treat extended tumors, new therapeutic strategies must be explored. This work aimed to combine ultrasound contrast agents (UCA) with flat transducers for increasing the treatment depth. The idea consists in increasing attenuation away from the transducer to favor remote heat deposition. Thermal ablation is induced in three steps. 1- Attenuation raises by injecting UCA; 2- Destruction of bubbles next to the transducer by pulsed high intensity bursts, results in a gradient of attenuation; 3- Continuous ultrasound are applied for generating a localized thermal lesion. In vitro tests were performed on temperature-sensitive tissue phantoms in which the UCA BR14 (Bracco) was injected during the liquid phase. The feasibility of the idea was demonstrated in three stages. 1- The coefficient of attenuation was measured with the force balance as a function of the concentration of BR14. For 0.8 and 4.8% attenuation at 10MHz was found to be 0.35 and 1.33 Np/cm respectively. 2- Pulsed ultrasound was applied on phantoms to destroy UCA. Based on the echogenicity decay evidenced on ultrasound images, a 1MPa-pressure was required at 10MHz. 3- Heating beams were applied on phantoms presenting a gradient in attenuation. Lesions were 1.5 times larger than in phantoms with constant attenuation. This study demonstrates that UCA can be selectively destroyed in order to generate a gradient of attenuation and extended thermal lesions.

  5. Spectral Signature of Column Solar Radiation Absorption During the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE). Revision

    SciTech Connect

    O'Hirok, William; Gautier, Catherine; Ricchiazzi, Paul

    1999-11-01

    Spectral and broadband shortwave radiative flux data obtained from the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE) are compared with 3-D radiative transfer computations for the cloud field of October 30, 1995. Because the absorption of broadband solar radiation in the cloudy atmosphere deduced from observations and modeled differ by 135 Wm{sup -2}, we performed a consistency analysis using spectral observations and the model to integrate for wavelengths between the spectral observations. To match spectral measurements, aerosols need a reduction in both single scattering albedo (from 0.938 to 0.82) and asymmetry factor (from 0.67 to 0.61), and cloud droplets require a three-fold increase in co-albedo. Even after modifying the model inputs and microphysics the difference in total broadband absorption is still of the order of 75Wm{sup -2}. Finally, an unexplained absorber centered around 1.06 {micro}m appears in the comparison that is much too large to be explained by dimers.

  6. Enhanced and broadband microwave absorption of flake-shaped Fe and FeNi composite with Ba ferrites

    NASA Astrophysics Data System (ADS)

    Li, Wangchang; Lv, Junjun; Zhou, Xiang; Zheng, Jingwu; Ying, Yao; Qiao, Liang; Yu, Jing; Che, Shenglei

    2017-03-01

    In order to achieve a broad bandwidth absorber at high frequency, the composites of M-type ferrite BaCo1.0Ti1.0Fe10O19 (BaM) with flaked carbonyl iron powders (CIP) and flaked Fe50Ni50 were prepared to optimize the surface impedance in broadband frequency, respectively. The diameter of the flaked carbonyl iron powders (CIP) and Fe50Ni50 is in the range of 5-10 μm and 10-20 μm and the thickness of the CIP and Fe50Ni50 is close to 200 nm and 400 nm, respectively. The complex permeability and permittivity show that the addition of BaM obviously reduces the values of real part of permittivity and imaginary part of the permeability which can enhance the matched-wave-impedance. The absorption bands less than -10 dB of CIP-BaM and FeNi-BaM absorber approach to 5.5 GHz (5.7-11.2 GHz) and 7 GHz (11-18 GHz) at 1.5 mm. However, the bands of CIP and FeNi are only 1.9 GHz (4.7-6.6 GHz) and 2.1 GHz (4.0-6.1 GHz). Hence, the electromagnetic match property is greatly improved by BaM ferrites, and this composite shows a broaden absorption band.

  7. Enhanced oral absorption of paclitaxel in N-deoxycholic acid-N, O-hydroxyethyl chitosan micellar system.

    PubMed

    Li, Hong; Huo, Meirong; Zhou, Jianping; Dai, Yindi; Deng, Yaping; Shi, Xiangjie; Masoud, Jumah

    2010-11-01

    The overall goal of this study was to develop a micellar system of paclitaxel (PTX) to enhance its oral absorption. An amphiphilic chitosan derivative, N-deoxycholic acid-N, O-hydroxyethyl chitosan (DHC), was synthesized and characterized by FTIR, (1)H NMR, elemental analysis, and X-ray diffraction (XRD) techniques. The degree of substitution (DS) of hydroxyethyl group and deoxycholic acid group ranged from 89.5-114.5% and 1.11-8.17%, respectively. The critical micelle concentration (CMC) values of DHC decreased from 0.26 to 0.16 mg/mL as the DS of deoxycholic acid group increased. PTX was successfully loaded in DHC micelles with a high drug loading (31.68 ± 0.14%) and entrapment efficiency (77.57 ± 0.51%). The particle size of PTX-loaded DHC micelles ranged from 203.35 ± 2.19 to 236.70 ± 3.40 nm as the DS of deoxycholic acid group increased. After orally administration of PTX-loaded DHC micelles, the bioavailability was threefold compared with that of an orally dosed Taxol®. The single-pass intestinal perfusion studies (SPIP) showed that the intestinal absorption of micelles was via endocytosis involving a saturable process and a p-glycoprotein (P-gp)-independent way. All these indicated that the DHC micelles might be a promising tool for oral delivery of poorly water-soluble drugs.

  8. Resonant and static cubic hyperpolarizabilities of push-pull dipolar and quadrupolar chromophores: toward enhanced two-photon absorption

    NASA Astrophysics Data System (ADS)

    Barzoukas, Marguerite; Blanchard-Desce, Mireille H.

    2001-12-01

    Recent reports of push-pull dipolar and quadrupolar chromophores with enhanced two-photon absorption have generated considerable interest in these two molecular systems. Two photon absorption is related to the imaginary part of the two-photon resonant cubic hyperpolarizability Im[(gamma) ((omega) )]. In this work, we have described both push-pull dipolar and quadrupolar chromophores using multi valence-bond states models based on measurable parameters of the valence-bond forms. We have derived analytical expressions of their non-resonant static cubic hyperpolarizability (gamma) (0) and of Im[(gamma) ((omega) )]. Comparison between the transparency / Im[(gamma) ((omega) )] trade-off and Im[(gamma) ((omega) )] / (gamma) (0) correlation helps understand the advantages and drawbacks of each of these two push-pull systems. Furthermore by understanding how the valence-bond parameters are related to the molecular structure and its environment, it is possible to predict how Im[(gamma) ((omega) )] will be affected by changing either the conjugation size, the donor-acceptor pair or the solvent polarity for both of these push-pull systems. The results of this study suggest common guidelines for the molecular engineering of both the push-pull dipolar and quadrupolar chromophores.

  9. Optical feedback cavity-enhanced absorption spectroscopy with a 3.24 μm interband cascade laser

    SciTech Connect

    Manfred, K. M.; Ritchie, G. A. D.; Lang, N.; Röpcke, J.; Helden, J. H. van

    2015-06-01

    The development of interband cascade lasers (ICLs) has made the strong C-H transitions in the 3 μm spectral region increasingly accessible. We present the demonstration of a single mode distributed feedback ICL coupled to a V-shaped optical cavity in an optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS) experiment. We achieved a minimum detectable absorption coefficient, α{sub min}, of (7.1±0.2)×10{sup −8} cm{sup −1} for a spectrum of CH{sub 4} at 3.24 μm with a two second acquisition time (100 scans averaged). This corresponds to a detection limit of 3 ppb CH{sub 4} at atmospheric pressure, which is comparable to previously reported OF-CEAS instruments with diode lasers or quantum cascade lasers. The ability to frequency lock an ICL source in the important 3 μm region to an optical cavity holds great promise for future spectroscopic applications.

  10. RF noise induced laser perturbation for improving the performance of non-resonant cavity enhanced absorption spectroscopy.

    PubMed

    Ciaffoni, Luca; Couper, John; Hancock, Gus; Peverall, Robert; Robbins, Peter A; Ritchie, Grant A D

    2014-07-14

    We present a novel strategy for suppressing mode structure which often degrades off-axis cavity enhanced absorption spectra. This strategy relies on promoting small, random fluctuations in the optical frequency by perturbing the injection current of the diode laser source with radio frequency (RF) bandwidth-limited white noise. A fast and compact oxygen sensor, constructed from a 764 nm vertical-cavity surface-emitting laser (VCSEL) and an optical cavity with re-entrant configuration, is employed to demonstrate the potential of this scheme for improving the sensitivity and robustness of a field-deployable cavity spectrometer. The RF spectral density of the current noise injected into the VCSEL has been measured, and correlated to the effects on the optical spectral signal-to-noise ratio (SNR) and laser linewidth for a range of re-entrant geometries. A fourfold gain in the SNR has been achieved using the RF noise perturbation for the optimal off-axis alignment, which led to a minimum detectable absorption (MDA) predicted from an Allan variance study as low as 4.3 × 10(-5) at 1 s averaging. For the optically forbidden oxygen transition under investigation, a limit of detection (SNR = 1) of 810 ppm was achieved for a 10 ms acquisition time. This performance level paves the way for a fast, sensitive, in-line oxygen spectrometer that lends itself to a range of applications in respiratory medicine.

  11. Enhanced absorption of microwave radiations through flexible polyvinyl alcohol-carbon black/barium hexaferrite composite films

    NASA Astrophysics Data System (ADS)

    Kumar, Sushil; Datt, Gopal; Santhosh Kumar, A.; Abhyankar, A. C.

    2016-10-01

    Flexible microwave absorber composite films of carbon black (CB)/barium hexaferrite nano-discs (BaF) in polyvinyl alcohol (PVA) matrix, fabricated by gel casting, exhibit ˜99.5% attenuation of electromagnetic waves in the entire 8-18 GHz (X and Ku-band) range. The X-ray diffraction and Raman spectroscopy studies confirm the formation of CB-BaF-PVA composite films. The electromagnetic absorption properties of composite films are found to be enhanced with CB content due to the synergetic effect of multiple dielectric and magnetic losses. The 25 wt. % CB grafted PVA-BaF flexible composite films with a thickness of ˜ 2 mm exhibit effective electromagnetic shielding of 23.6 dB with a dominant contribution from absorption mechanism (SEA ˜ 21 dB). The dielectric properties of composite films are further discussed by using the Debye model. The detailed analysis reveals that major contribution to dielectric losses is from dipolar and interfacial polarizations, whereas magnetic losses are predominantly from domain wall displacement.

  12. Broadband antireflection and absorption enhancement of ultrathin silicon solar microcells enabled with density-graded surface nanostructures

    SciTech Connect

    Chan, Lesley; Kang, Dongseok; Lee, Sung-Min; Li, Weigu; Hunter, Hajirah; Yoon, Jongseung

    2014-06-02

    Density-graded surface nanostructures are implemented on ultrathin silicon solar microcells by silver-nanoparticle-catalyzed wet chemical etching to enable near-zero surface reflection over a broad wavelength range of incident solar spectrum as well as non-zeroth order diffraction and light trapping for longer wavelength photons, thereby achieving augmented photon absorption for ultrathin silicon microcells in a simple, cost-effective manner. The increase of absorbed photon flux through the “black silicon (b-Si)” surface translates directly into the corresponding enhancement of photovoltaic performance, where 5.7-μm b-Si microcells with the rational design of device configuration exhibit improved energy conversion efficiency by 148% and 50% with and without a diffuse backside reflector, respectively, compared to devices from the bare silicon without b-Si implementation. Systematic studies on nanostructured morphology, optical and electrical properties of b-Si microcells, together with semi-empirical numerical modeling of photon absorption, provide key aspects of underlying materials science and physics.

  13. Titania hollow spheres modified with tungstophosphoric acid with enhanced visible light absorption for the photodegradation of 4-chlorophenol.

    PubMed

    Orellana, M Á; Osiglio, L; Arnal, P M; Pizzio, L R

    2017-01-18

    Titania hollow spheres were synthesized using silica nanospheres as the template. The core was removed using NaOH solution. They were subsequently impregnated with tungstophosphoric acid (TPA) solutions and annealed at two different temperatures (100 and 500 °C). These materials were characterized by several physicochemical techniques (XRD, BET, SEM, DRS, FT-IR, FT-Raman and (31)P MAS-NMR). The (31)P MAS-NMR and FT-IR characterization showed that the main species present in the samples was the [PW12O40](3-) anion, which was partially transformed into the [P2W21O71](6-) anion during the synthesis and drying step. (31)P MAS-NMR, and FT-Raman characterization revealed the evidence of a strong interaction between the Keggin anion of TPA and TiO2 surfaces, possibly due to the formation of surface heteropolyacid-TiO2 complexes. The DRS results showed that the absorption threshold onset continuously shifted to the visible region with increased TPA concentration and calcination at 500 °C. The enhanced visible light absorption could be related to the formation of a surface complex TPA Keggin anion-TiO2. The catalytic activity of the materials in the photodegradation of 4-chlorophenol under UV and visible light irradiation increased when the TPA content and the calcination temperature of the samples were raised.

  14. Enhanced two-photon absorption and fluorescence upconversion in Thioflavin T micelle-type aggregates in glycerol/water solution

    NASA Astrophysics Data System (ADS)

    Donnelly, Julie; Vesga, Yuly; Hernandez, Florencio E.

    2016-09-01

    In this article, we report the systematic characterization of the two-photon absorption of ThT in different mixtures of glycerol/water solution. The relationships of TPA peak position and amplitude revealed a dependence on particle size suggesting that the curious trend observed in TPA with changing glycerol content can be attributed to the presence of micelle-type aggregates. Consequently, the relatively strong TPA cross-section (δTPA = 300 GM) obtained in 8.75% glycerol/water solutions could be attributed to the immobilization of dye molecules and the strong coupling of the molecular transition dipoles in micelle-type aggregates. This enhancement of TPA, in addition to the already reported significant fluorescence quantum yield of ThT attached to brain tissue, is expected to boost the application of this compound for in vitro and perhaps in vivo high resolution multiphoton bioimaging of amyloids in brain tissue.

  15. Enhancement of two photon absorption with Ni doping in the dilute magnetic semiconductor ZnO crystalline nanorods

    NASA Astrophysics Data System (ADS)

    Rana, Amit Kumar; J, Aneesh; Kumar, Yogendra; M. S, Arjunan; Adarsh, K. V.; Sen, Somaditya; Shirage, Parasharam M.

    2015-12-01

    In this letter, we have investigated the third-order optical nonlinearities of high-quality Ni doped ZnO nanorods crystallized in wurtzite lattice, prepared by the wet chemical method. In our experiments, we found that the two photon absorption coefficient (β) increases by as much as 14 times, i.e., 7.6 ± 0.4 to 112 ± 6 cm/GW, when the Ni doping is increased from 0% to 10%. The substantial enhancement in β is discussed in terms of the bandgap scaling and Ni doping. Furthermore, we also show that the optical bandgap measured by UV-Vis and photoluminescence spectroscopies, continuously redshift with increasing Ni doping concentration. We envision that the strong nonlinear optical properties together with their dilute magnetic effects, they form an important class of materials for potential applications in magneto-optical and integrated optical chips.

  16. Natural dyes adsorbed on TiO2 nanowire for photovoltaic applications: enhanced light absorption and ultrafast electron injection.

    PubMed

    Meng, Sheng; Ren, Jun; Kaxiras, Efthimios

    2008-10-01

    We investigate the electronic coupling between a TiO2 nanowire and a natural dye sensitizer, using state-of-the-art time-dependent first-principles calculations. The model dye molecule, cyanidin, is deprotonated into the quinonoidal form upon adsorption on the wire surface. This results in its highest occupied molecular orbital (HOMO) being located in the middle of the TiO2 bandgap and its lowest unoccupied molecular orbital (LUMO) being close to the TiO2 conduction band minimum (CBM), leading to greatly enhanced visible light absorption with two prominent peaks at 480 and 650 nm. We find that excited electrons are injected into the TiO2 conduction band within a time scale of 50 fs with negligible electron-hole recombination and energy dissipation, even though the dye LUMO is located 0.1-0.3 eV lower than the CBM of the TiO2 nanowire.

  17. UV-Visible Absorption Spectroscopy Enhanced X-ray Crystallography at Synchrotron and X-ray Free Electron Laser Sources.

    PubMed

    Cohen, Aina E; Doukov, Tzanko; Soltis, Michael S

    2016-01-01

    This review describes the use of single crystal UV-Visible Absorption micro-Spectrophotometry (UV-Vis AS) to enhance the design and execution of X-ray crystallography experiments for structural investigations of reaction intermediates of redox active and photosensitive proteins. Considerations for UV-Vis AS measurements at the synchrotron and associated instrumentation are described. UV-Vis AS is useful to verify the intermediate state of an enzyme and to monitor the progression of reactions within crystals. Radiation induced redox changes within protein crystals may be monitored to devise effective diffraction data collection strategies. An overview of the specific effects of radiation damage on macromolecular crystals is presented along with data collection strategies that minimize these effects by combining data from multiple crystals used at the synchrotron and with the X-ray free electron laser.

  18. The enhanced photo absorption and carrier transportation of InGaN/GaN Quantum Wells for photodiode detector applications.

    PubMed

    Yang, Haojun; Ma, Ziguang; Jiang, Yang; Wu, Haiyan; Zuo, Peng; Zhao, Bin; Jia, Haiqiang; Chen, Hong

    2017-02-27

    We have conducted a series of measurements of resonantly excited photoluminescence, photocurrent and photovoltage on InGaN/GaN quantum wells with and without a p-n junction under reverse bias condition. The results indicate that most of the resonantly excited photo-generated carriers are extracted from the quantum wells when a p-n junction exists, and the photon absorption of quantum wells is enhanced by the p-n junction. Additionally, the carrier extraction becomes more distinct under a reverse bias. Our finding brings better understanding of the physical characteristics of quantum wells with p-n junction, which also suggests that the quantum well is suitable for photodiode detectors applications when a p-n junction is used.

  19. The enhanced photo absorption and carrier transportation of InGaN/GaN Quantum Wells for photodiode detector applications

    PubMed Central

    Yang, Haojun; Ma, Ziguang; Jiang, Yang; Wu, Haiyan; Zuo, Peng; Zhao, Bin; Jia, Haiqiang; Chen, Hong

    2017-01-01

    We have conducted a series of measurements of resonantly excited photoluminescence, photocurrent and photovoltage on InGaN/GaN quantum wells with and without a p-n junction under reverse bias condition. The results indicate that most of the resonantly excited photo-generated carriers are extracted from the quantum wells when a p-n junction exists, and the photon absorption of quantum wells is enhanced by the p-n junction. Additionally, the carrier extraction becomes more distinct under a reverse bias. Our finding brings better understanding of the physical characteristics of quantum wells with p-n junction, which also suggests that the quantum well is suitable for photodiode detectors applications when a p-n junction is used. PMID:28240254

  20. Enhancement of two photon absorption with Ni doping in the dilute magnetic semiconductor ZnO crystalline nanorods

    SciTech Connect

    Rana, Amit Kumar; Kumar, Yogendra; Arjunan, M.S.; Sen, Somaditya; Shirage, Parasharam M. E-mail: paras.shirage@gmail.com; J, Aneesh; Adarsh, K. V.

    2015-12-07

    In this letter, we have investigated the third-order optical nonlinearities of high-quality Ni doped ZnO nanorods crystallized in wurtzite lattice, prepared by the wet chemical method. In our experiments, we found that the two photon absorption coefficient (β) increases by as much as 14 times, i.e., 7.6 ± 0.4 to 112 ± 6 cm/GW, when the Ni doping is increased from 0% to 10%. The substantial enhancement in β is discussed in terms of the bandgap scaling and Ni doping. Furthermore, we also show that the optical bandgap measured by UV-Vis and photoluminescence spectroscopies, continuously redshift with increasing Ni doping concentration. We envision that the strong nonlinear optical properties together with their dilute magnetic effects, they form an important class of materials for potential applications in magneto-optical and integrated optical chips.

  1. Cavity Enhanced Absorption Spectroscopy using a Prism Cavity and Supercontinuum Source

    NASA Astrophysics Data System (ADS)

    Lehmann, Kevin K.; Johnston, Paul S.

    2010-03-01

    The multiplex advantage of current cavity enhanced spectrometers is limited by the limited high reflectivity bandwidth of the dielectric mirrors used to construct the high finesse cavity. We report on our development of a spectrometer that uses Brewster's angle retroreflectors that is excited with supercontinuum radiation generated by a 1.06 μm pumped photonic crystal fiber, which covers the 500-1800 nm spectral range. Recent progress will be discussed including modeling of the prism cavity losses, alternative prism materials for use in the UV and mid-IR, and a new higher power source pumped by a mode-locked laser.

  2. Enhanced light absorption of silicon nanotube arrays for organic/inorganic hybrid solar cells.

    PubMed

    Jeong, Huisu; Song, Hui; Pak, Yusin; Kwon, Il Keun; Jo, Kyubong; Lee, Heon; Jung, Gun Young

    2014-06-04

    By combining nanoimprint lithography technique and a two-step lift-off process, a Si nanotube array is fabricated and applied as a light absorber for n-Si/PEDOT:PSS hybrid solar cells. The light is effectively trapped within the nanotubes and the device reveals a Jsc of 29.9 mA · cm(-2) and a power conversion efficiency of 10.03%, which is an enhancement of 13.4% compared to the cell having the best-known Si architecture of nanocones as a light absorber to date.

  3. Enhanced absorption of boswellic acids by a lecithin delivery form (Phytosome(®)) of Boswellia extract.

    PubMed

    Hüsch, Jan; Bohnet, Janine; Fricker, Gert; Skarke, Carsten; Artaria, Christian; Appendino, Giovanni; Schubert-Zsilavecz, Manfred; Abdel-Tawab, Mona

    2013-01-01

    The anti-inflammatory potential of Boswellia serrata gum resin extracts has been demonstrated in vitro and in animal studies as well as in pilot clinical trials. However, pharmacokinetic studies have evidenced low systemic absorption of boswellic acids (BAs), especially of KBA and AKBA, in rodents and humans. This observation has provided a rationale to improve the formulation of Boswellia extract. We present here the results of a murine comparative bioavailability study of Casperome™, a soy lecithin formulation of standardized B. serrata gum resin extract (BE), and its corresponding non-formulated extract. The concentration of the six major BAs [11-keto-β-boswellic acid (KBA), acetyl-11-keto-β-boswellic acid (AKBA), β-boswellic acid (βBA), acetyl-β-boswellic acid (AβBA), α-boswellic acid (αBA), and acetyl-α-boswellic acid (AαBA)] was evaluated in the plasma and in a series of tissues (brain, muscle, eye, liver and kidney), providing the first data on tissue distribution of BAs. Weight equivalent and equimolar oral administration of Casperome™ provided significantly higher plasma levels (up to 7-fold for KBA, and 3-fold for βBA quantified as area under the plasma concentration time curve, AUC(last)) compared to the non-formulated extract. This was accompanied by remarkably higher tissue levels. Of particular relevance was the marked increase in brain concentration of KBA and AKBA (35-fold) as well as βBA (3-fold) following Casperome™ administration. Notably, up to 17 times higher BA levels were observed in poorly vascularized organs such as the eye. The increased systemic availability of BAs and the improved tissue distribution, qualify Casperome™ for further clinical development to fully exploit the clinical potential of BE.

  4. Enhancing Middle School Students' Scientific Learning and Motivation through Agent-Based Learning

    ERIC Educational Resources Information Center

    Chen, C.-H.; Chou, M.-H.

    2015-01-01

    Facing students' decreasing motivation to pursue scientific study, schools and educators need to coordinate new technologies with pedagogical agents to effectively sustain or promote students' scientific learning and motivation to learn. Although the provision of pedagogical agents in student learning has been studied previously, it is not clear…

  5. Using Agent-Based Technologies to Enhance Learning in Educational Games

    ERIC Educational Resources Information Center

    Tumenayu, Ogar Ofut; Shabalina, Olga; Kamaev, Valeriy; Davtyan, Alexander

    2014-01-01

    Recent research has shown that educational games positively motivate learning. However, there is a little evidence that they can trigger learning to a large extent if the game-play is supported by additional activities. We aim to support educational games development with an Agent-Based Technology (ABT) by using intelligent pedagogical agents that…

  6. How does the plasmonic enhancement of molecular absorption depend on the energy gap between molecular excitation and plasmon modes: a mixed TDDFT/FDTD investigation.

    PubMed

    Sun, Jin; Li, Guang; Liang, WanZhen

    2015-07-14

    A real-time time-dependent density functional theory coupled with the classical electrodynamics finite difference time domain technique is employed to systematically investigate the optical properties of hybrid systems composed of silver nanoparticles (NPs) and organic adsorbates. The results demonstrate that the molecular absorption spectra throughout the whole energy range can be enhanced by the surface plasmon resonance of Ag NPs; however, the absorption enhancement ratio (AER) for each absorption band differs significantly from the others, leading to the quite different spectral profiles of the hybrid complexes in contrast to those of isolated molecules or sole NPs. Detailed investigations reveal that the AER is sensitive to the energy gap between the molecular excitation and plasmon modes. As anticipated, two separate absorption bands, corresponding to the isolated molecules and sole NPs, have been observed at a large energy gap. When the energy gap approaches zero, the molecular excitation strongly couples with the plasmon mode to form the hybrid exciton band, which possesses the significantly enhanced absorption intensity, a red-shifted peak position, a surprising strongly asymmetric shape of the absorption band, and the nonlinear Fano effect. Furthermore, the dependence of surface localized fields and the scattering response functions (SRFs) on the geometrical parameters of NPs, the NP-molecule separation distance, and the external-field polarizations has also been depicted.

  7. Classification of chemical and biological warfare agent simulants by surface-enhanced Raman spectroscopy and multivariate statistical techniques.

    PubMed

    Pearman, William F; Fountain, Augustus W

    2006-04-01

    Initial results demonstrating the ability to classify surface-enhanced Raman (SERS) spectra of chemical and biological warfare agent simulants are presented. The spectra of two endospores (B. subtilis and B. atrophaeus), two chemical agent simulants (dimethyl methylphosphonate (DMMP) and diethyl methylphosphonate (DEMP)), and two toxin simulants (ovalbumin and horseradish peroxidase) were studied on multiple substrates fabricated from colloidal gold adsorbed onto a silanized quartz surface. The use of principal component analysis (PCA) and hierarchical clustering were used to evaluate the efficacy of identifying potential threat agents from their spectra collected on a single substrate. The use of partial least squares-discriminate analysis (PLS-DA) and soft independent modeling of class analogies (SIMCA) on a compilation of data from separate substrates, fabricated under identical conditions, demonstrates both the feasibility and the limitations of this technique for the identification of known but previously unclassified spectra.

  8. Enhanced microwave absorption performance of lightweight absorber based on reduced graphene oxide and Ag-coated hollow glass spheres/epoxy composite

    SciTech Connect

    Wang, Junpeng; Sun, Yu; Chen, Wei; Wang, Tao; Xu, Renxin; Wang, Jun

    2015-04-21

    Using a combination of Ag-coated hollow glass spheres (HGS@Ag) and a small quantity of graphene sheets within the epoxy matrix, we have prepared a novel lightweight high efficiency microwave absorption composite. Compared with pure HGS@Ag and graphene composite, the −10 dB absorption bandwidth and the minimum reflection loss of the novel composite are improved. Reflection loss exceeding −20 dB is obtained for composites in a wide frequency range and the minimum reflection loss reaches −46 dB while bandwidth less than −10 dB can reach up to 4.1 GHz when an appropriate absorber thickness between 2 and 3.5 mm is chosen. The enhanced microwave absorption performance of the novel composite is due to the enhanced dielectric response, enhanced conductivity, and the trap of electromagnetic radiation with increased propagation paths by multiple reflections.

  9. Transdermal absorption of radioprotectors in the rat using permeation-enhancing vehicles

    SciTech Connect

    Lamperti, A.; Ziskin, M.C.; Bergey, E.; Gorlowski, J.; Sodicoff, M. )

    1990-11-01

    Topical radioprotection of rat skin with WR-2721 has not been effective presumably because the drug does not cross the stratum corneum to reach the epidermis and dermis. Earlier, we showed in the mouse that WR-2721 and cysteine dissolved in permeation-enhancing vehicles passed through the skin more readily than when in water. However, the most effective vehicles in the mouse were not necessarily as effective in the rat. Here we report that the most effective transport vehicles in the rat were (1) water with WR-2721, (2) water and dimethylformamide (DMF) with cysteine, and (3) water and DMF with prostaglandin E2 (PGE2). Pretreatment of the skin with dimethylsulfoxide (DMSO) further improved the transfer of the radioprotectors across the skin in most cases. After pretreatment with DMSO, the most effective vehicles were (1) water for WR-2721, (2) water and methyl-2-pyrrolidone (M-2-P) for cysteine, and (3) DMF for PGE2.

  10. Cavity Enhanced Absorption Spectroscopy Using a Broadband Prism Cavity and a Supercontinuum Source

    NASA Astrophysics Data System (ADS)

    Johnston, Paul S.; Lehmann, Kevin K.

    2009-06-01

    The multiplex advantage of current cavity enhanced spectrometers is limited by the high reflectivity bandwidth of the mirrors used to construct the high finesse cavity. Previously, we reported the design and construction of a new spectrometer that circumvents this limitation by utilizing Brewster^{,}s angle prism retroreflectors. The prisms, made from fused silica and combined with a supercontinuum source generated by pumping a highly nonlinear photonic crystal fiber, yields a spectral window ranging from 500 nm to 1750 nm. Recent progress in the instruments development will be discussed, including work on modeling the prism cavity losses, alternative prism material for use in the UV and mid-IR spectral regions, and a new high power supercontinuum source based on mode-locked picosecond laser.

  11. Enhanced vacuum laser-impulse coupling by volume absorption at infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Phipps, C. R., Jr.; Harrison, R. F.; Shimada, T.; York, G. W.; Turner, R. F.

    1990-03-01

    This paper reports measurements of vacuum laser impulse coupling coefficients as large as 90 dyne/W, obtained with single microsec-duration CO2 laser pulses incident on a volume-absorbing, cellulose-nitrate-based plastic. This result is the largest coupling coefficient yet reported at any wavelength for a simple, planar target in vacuum, and partly results from expenditure of internal chemical energy in this material. Enhanced coupling was also observed in several other target materials that are chemically passive, but absorb light in depth at 10- and 3-micron wavelengths. The physical distinctions are discussed between this important case and that of simple, planar surface absorbers (such as metals) which were studied in the same experimental series, in light of the predictions of a simple theoretical model.

  12. The potential for solubilizing agents to enhance the remediation of hydrophobic organic solutes in soil-water suspensions. [Quarterly report

    SciTech Connect

    Laha, S.; Liu, Z.; Edwards, D.; Luthy, R.G.

    1991-02-01

    This paper discusses the feasibility for use of surfactant solubilizing agents to enhance the solubility and the rate of microbial degradation of hydrophobic organic solutes in soil-water suspensions. Hydrophobic organic contaminants are strongly sorbed to soil or sediment material, and as a consequence the rate of microbial degradation may depend greatly on the desorption of the sorbed-phase contaminant and the accessibility of the contaminant to soil microorganisms. Chemical solubilizing agents may enhance the rate of hydrophobic organic solute degradation by increasing the rate of solute desorption from soil and the extent of solute partitioning to the aqueous phase. The presentation will review on-going research on: surfactant solubilization of polycyclic aromatic hydrocarbon (PAH) compounds in clean water, and in soil-water suspensions; and experiments to assess if the addition of surfactant to soil-water suspension results in faster rate of mineralization of PAH compounds in soil.

  13. The potential for solubilizing agents to enhance the remediation of hydrophobic organic solutes in soil-water suspensions

    SciTech Connect

    Laha, S.; Liu, Z.; Edwards, D.; Luthy, R.G.

    1991-02-01

    This paper discusses the feasibility for use of surfactant solubilizing agents to enhance the solubility and the rate of microbial degradation of hydrophobic organic solutes in soil-water suspensions. Hydrophobic organic contaminants are strongly sorbed to soil or sediment material, and as a consequence the rate of microbial degradation may depend greatly on the desorption of the sorbed-phase contaminant and the accessibility of the contaminant to soil microorganisms. Chemical solubilizing agents may enhance the rate of hydrophobic organic solute degradation by increasing the rate of solute desorption from soil and the extent of solute partitioning to the aqueous phase. The presentation will review on-going research on: surfactant solubilization of polycyclic aromatic hydrocarbon (PAH) compounds in clean water, and in soil-water suspensions; and experiments to assess if the addition of surfactant to soil-water suspension results in faster rate of mineralization of PAH compounds in soil.

  14. Perspectives on the Use of Scopolamine as an Adjunct Treatment to Enhance Survival Following Organophosphorus Nerve Agent Poisoning

    DTIC Science & Technology

    2010-11-01

    MILITARY MEDICINE, 175, 11:878,2010 Perspectives on the Use of Scopolamine as an Adjunct Treatment to Enhance Survival Following Organophosphorus...Nerve Agent Poisoning Irwin Koplovitz, RhD; Susan Schulz ABSTRACT Scopolamine (SCP) is an anticholinergic drug used clinically for decades to treat...PB is currently EDA approved only for use against soman. Scopolamine (SCP) is a well known anticholinergic drug that has been used clinically for

  15. Definition of contrast enhancement phases of the liver using a perfluoro-based microbubble agent, perflubutane microbubbles.

    PubMed

    Shunichi, Sasaki; Hiroko, Iijima; Fuminori, Moriyasu; Waki, Hidehiko

    2009-11-01

    To define the contrast enhancement phases in the liver with perflubutane microbubbles, the liver enhancement time-intensity curves were investigated in 14 healthy volunteers. The agent was injected intravenously as a bolus and the liver was imaged with an ultrasound scanner as long as 4h after the injection. Time-intensity curves from the hepatic artery, the intrahepatic portal vein, the hepatic vein and the parenchyma of the liver were obtained from the liver ultrasound images. The arrival of the agent in the hepatic artery, the portal vein and the hepatic vein were visually distinguishable and the mean arrival times were 19.2, 24.3 and 32.2 s after the injection, respectively. The signal intensity in these vessels increased rapidly after the arrival of the contrast and gradually reverted to baseline after the peak. In contrast, within 5 min after the injection, the intensity in the parenchyma increased and reached a plateau, which persisted for at least 2h. The contrast enhancement phases in the liver with perflubutane microbubbles could be defined as two major phases-a vascular phase, in which the vessels are enhanced between 15 s and 10 min after injection, and a Kupffer phase, in which the parenchyma is enhanced 10 min after injection. The vascular phase is divided into three subphases: the arterial phase (15 to 45 s after injection); the portal phase (45 s to 1 min after injection); and the vasculo-Kupffer phase (1 to 10 min after injection).

  16. Enhanced bioavailability of a poorly water-soluble weakly basic compound using a combination approach of solubilization agents and precipitation inhibitors: a case study.

    PubMed

    Li, Shu; Pollock-Dove, Crystal; Dong, Liang C; Chen, Jing; Creasey, Abla A; Dai, Wei-Guo

    2012-05-07

    Poorly water-soluble weakly basic compounds which are solubilized in gastric fluid are likely to precipitate after the solution empties from the stomach into the small intestine, leading to a low oral bioavailability. In this study, we reported an approach of combining solubilization agents and precipitation inhibitors to produce a supersaturated drug concentration and to prolong such a drug concentration for an extended period of time for an optimal absorption, thereby improving oral bioavailability of poorly water-soluble drugs. A weakly basic compound from Johnson and Johnson Pharmaceutical Research and Development was used as a model compound. A parallel microscreening precipitation method using 96-well plates and a TECAN robot was used to assess the precipitation of the tested compound in the simulated gastric fluid (SGF) and the simulated intestinal fluid (SIF), respectively, for lead solubilizing agents and precipitation inhibitors. The precipitation screening results showed vitamin E TPGS was an effective solubilizing agent and Pluronic F127 was a potent precipitation inhibitor for the tested compound. Interestingly, the combination of Pluronic F127 with vitamin E TPGS resulted in a synergistic effect in prolonging compound concentration upon dilution in SIF. In addition, HPMC E5 and Eudragit L100-55 were found to be effective precipitation inhibitors for the tested compounds in SGF. Furthermore, optimization DOE study results suggested a formulation sweet spot comprising HPMC, Eudragit L 100-55, vitamin E TPGS, and Pluronic F127. The lead formulation maintained the tested compound concentration at 300 μg/mL upon dilution in SIF, and more than 70% of the compound remained solubilized compared with the compound alone at <1 μg/mL of its concentration. Dosing of the solid dosage form predissolved in SGF in dogs resulted in 52% of oral bioavailability compared to 26% for the suspension control, a statistically significant increase (p = 0.002). The enhanced

  17. Paenibacillus polymyxa BFKC01 enhances plant iron absorption via improved root systems and activated iron acquisition mechanisms.

    PubMed

    Zhou, Cheng; Guo, Jiansheng; Zhu, Lin; Xiao, Xin; Xie, Yue; Zhu, Jian; Ma, Zhongyou; Wang, Jianfei

    2016-08-01

    Despite the high abundance of iron (Fe) in most earth's soils, Fe is the major limiting factor for plant growth and development due to its low bioavailability. With an increasing recognition that soil microbes play important roles in plant growth, several strains of beneficial rhizobactria have been applied to improve plant nutrient absorption, biomass, and abiotic or biotic stress tolerance. In this study, we report the mechanisms of microbe-induced plant Fe assimilation, in which the plant growth promoting rhizobacteria (PGPR) Paenibacillus polymyxa BFKC01 stimulates plant's Fe acquisition machinery to enhance Fe uptake in Arabidopsis plants. Mechanistic studies show that BFKC01 transcriptionally activates the Fe-deficiency-induced transcription factor 1 (FIT1), thereby up-regulating the expression of IRT1 and FRO2. Furthermore, BFKC01 has been found to induce plant systemic responses with the increased transcription of MYB72, and the biosynthetic pathways of phenolic compounds are also activated. Our data reveal that abundant phenolic compounds are detected in root exudation of the BFKC01-inoculated plants, which efficiently facilitate Fe mobility under alkaline conditions. In addition, BFKC01 can secret auxin and further improved root systems, which enhances the ability of plants to acquire Fe from soils. As a result, BFKC01-inoculated plants have more endogenous Fe and increased photosynthetic capacity under alkaline conditions as compared to control plants. Our results demonstrate the potential roles of BFKC01 in promoting Fe acquisition in plants and underline the intricate integration of microbial signaling in controlling plant Fe acquisition.

  18. Fan-shaped gold nanoantennas above reflective substrates for surface-enhanced infrared absorption (SEIRA) (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Yang, Xiao; Brown, Lisa V.; Zhao, Ke; Zheng, Bob Y.; Nordlander, Peter; Halas, Naomi J.

    2015-08-01

    Surface-enhanced infrared absorption (SEIRA) has been gaining substantial attention by using plasmonic nanoantennas to amplify near-field intensities so that it can extend IR spectroscopy to zeptomolar quantities and ultimately to the sigle-molecule level. Here we report a new nanoantenna for SEIRA detection, consisting of a fan-shaped Au structure positioned at a well-specified distance above a reflective plane with an intervening silica spacer layer. This antenna can be easily tuned to overlap vibrational modes within a broad spectral range from the near-IR into terahertz regimes. Our finite difference time domain (FDTD) simulations reveal a maximum SEIRA enhancement factor of 105 in the antenna junction area, which is corresponding to the experimental detection of 20-200 zeptomoles of octadecanethiol, using a standard commercial FTIR spectrometer. Our optimized antenna exhibits an order of magnitude greater SEIRA sensitivity than previous record-setting designs, which opens new opportunities for using infrared spectroscopy to analyze exceptionally small quantities of molecules.

  19. Enhancing the efficacy of cytotoxic agents for cancer therapy using photochemical internalisation.

    PubMed

    Martinez de Pinillos Bayona, Alejandra; Moore, Caroline M; Loizidou, Marilena; MacRobert, Alexander J; Woodhams, Josephine H

    2016-03-01

    Photochemical internalisation (PCI) is a technique for improving cellular delivery of certain bioactive agents which are prone to sequestration within endolysosomes. There is a wide range of agents suitable for PCI-based delivery including toxins, oligonucleotides, genes and immunoconjugates which demonstrates the versatility of this technique. The basic mechanism of PCI involves triggering release of the agent from endolysosomes within the target cells using a photosensitiser which is selectively retained with the endolysosomal membranes. Excitation of the photosensitiser by visible light leads to disruption of the membranes via photooxidative damage thereby releasing the agent into the cytosol. This treatment enables the drugs to reach their intended subcellular target more efficiently and improves their efficacy. In this review we summarise the applications of this technique with the main emphasis placed on cancer chemotherapy.

  20. Enhancing the efficacy of cytotoxic agents for cancer therapy using photochemical internalisation

    PubMed Central

    Moore, Caroline M.; Loizidou, Marilena; MacRobert, Alexander J.; Woodhams, Josephine H.

    2016-01-01

    Photochemical internalisation (PCI) is a technique for improving cellular delivery of certain bioactive agents which are prone to sequestration within endolysosomes. There is a wide range of agents suitable for PCI‐based delivery including toxins, oligonucleotides, genes and immunoconjugates which demonstrates the versatility of this technique. The basic mechanism of PCI involves triggering release of the agent from endolysosomes within the target cells using a photosensitiser which is selectively retained with the endolysosomal membranes. Excitation of the photosensitiser by visible light leads to disruption of the membranes via photooxidative damage thereby releasing the agent into the cytosol. This treatment enables the drugs to reach their intended subcellular target more efficiently and improves their efficacy. In this review we summarise the applications of this technique with the main emphasis placed on cancer chemotherapy. PMID:25758607