Sample records for absorption efficiency mae

  1. Mass absorption efficiency of elemental carbon over Van Vihar National Park, Bhopal, India: Temporal variability and implications to estimates of black carbon radiative forcing

    NASA Astrophysics Data System (ADS)

    Samiksha, S.; Raman, R. S.; Singh, A.

    2016-12-01

    It is now well recognized that black carbon (a component of aerosols that is similar but not identical to elemental carbon) is an important contributor to global warming, second only to CO2.However, the most popular methods for estimation of black carbon rely on accurate estimates of its mass absorption efficiency (MAE) to convert optical attenuation measurements to black carbon concentrations. Often a constant manufacturer specified MAE is used for this purposes. Recent literature has unequivocally established that MAE shows large spatio-temporal heterogeneities. This is so because MAE depends on emission sources, chemical composition, and mixing state of aerosols. In this study, ambient PM2.5 samples were collected over an ecologically sensitive zone (Van Vihar National Park) in Bhopal, Central India for two years (01 January, 2012 to 31 December, 2013). Samples were collected on Teflon, Nylon, and Tissue quartz filter substrates. Punches of quartz fibre filter were analysed for organic and elemental carbon (OC/EC) by a thermal-optical-transmittance/reflectance (TOT-TOR) analyser operating with a 632 nm laser diode. Teflon filters were also used to interdependently measure PM2.5 attenuation (at 370 nm and 800 nm) by transmissometry. Site-specific mass absorption efficiency (MAE) for elemental carbon over the study site will be derived using a combination of measurements from the TOT/TOR analyser and transmissometer. An assessment of site-specific MAE values, its temporal variability and implications to black carbon radiative forcing will be discussed. It is now well recognized that black carbon (a component of aerosols that is similar but not identical to elemental carbon) is an important contributor to global warming, second only to CO2. However, the most popular methods for estimation of black carbon rely on accurate estimates of its mass absorption efficiency (MAE) to convert optical attenuation measurements to black carbon concentrations. Often a constant

  2. Optimization of microwave-assisted extraction with saponification (MAES) for the determination of polybrominated flame retardants in aquaculture samples.

    PubMed

    Fajar, N M; Carro, A M; Lorenzo, R A; Fernandez, F; Cela, R

    2008-08-01

    The efficiency of microwave-assisted extraction with saponification (MAES) for the determination of seven polybrominated flame retardants (polybrominated biphenyls, PBBs; and polybrominated diphenyl ethers, PBDEs) in aquaculture samples is described and compared with microwave-assisted extraction (MAE). Chemometric techniques based on experimental designs and desirability functions were used for simultaneous optimization of the operational parameters used in both MAES and MAE processes. Application of MAES to this group of contaminants in aquaculture samples, which had not been previously applied to this type of analytes, was shown to be superior to MAE in terms of extraction efficiency, extraction time and lipid content extracted from complex matrices (0.7% as against 18.0% for MAE extracts). PBBs and PBDEs were determined by gas chromatography with micro-electron capture detection (GC-muECD). The quantification limits for the analytes were 40-750 pg g(-1) (except for BB-15, which was 1.43 ng g(-1)). Precision for MAES-GC-muECD (%RSD < 11%) was significantly better than for MAE-GC-muECD (%RSD < 20%). The accuracy of both optimized methods was satisfactorily demonstrated by analysis of appropriate certified reference material (CRM), WMF-01.

  3. Spectral- and size-resolved mass absorption efficiency of mineral dust aerosols in the shortwave spectrum: a simulation chamber study

    NASA Astrophysics Data System (ADS)

    Caponi, Lorenzo; Formenti, Paola; Massabó, Dario; Di Biagio, Claudia; Cazaunau, Mathieu; Pangui, Edouard; Chevaillier, Servanne; Landrot, Gautier; Andreae, Meinrat O.; Kandler, Konrad; Piketh, Stuart; Saeed, Thuraya; Seibert, Dave; Williams, Earle; Balkanski, Yves; Prati, Paolo; Doussin, Jean-François

    2017-06-01

    This paper presents new laboratory measurements of the mass absorption efficiency (MAE) between 375 and 850 nm for 12 individual samples of mineral dust from different source areas worldwide and in two size classes: PM10. 6 (mass fraction of particles of aerodynamic diameter lower than 10.6 µm) and PM2. 5 (mass fraction of particles of aerodynamic diameter lower than 2.5 µm). The experiments were performed in the CESAM simulation chamber using mineral dust generated from natural parent soils and included optical and gravimetric analyses. The results show that the MAE values are lower for the PM10. 6 mass fraction (range 37-135 × 10-3 m2 g-1 at 375 nm) than for the PM2. 5 (range 95-711 × 10-3 m2 g-1 at 375 nm) and decrease with increasing wavelength as λ-AAE, where the Ångström absorption exponent (AAE) averages between 3.3 and 3.5, regardless of size. The size independence of AAE suggests that, for a given size distribution, the dust composition did not vary with size for this set of samples. Because of its high atmospheric concentration, light absorption by mineral dust can be competitive with black and brown carbon even during atmospheric transport over heavy polluted regions, when dust concentrations are significantly lower than at emission. The AAE values of mineral dust are higher than for black carbon (˜ 1) but in the same range as light-absorbing organic (brown) carbon. As a result, depending on the environment, there can be some ambiguity in apportioning the aerosol absorption optical depth (AAOD) based on spectral dependence, which is relevant to the development of remote sensing of light-absorbing aerosols and their assimilation in climate models. We suggest that the sample-to-sample variability in our dataset of MAE values is related to regional differences in the mineralogical composition of the parent soils. Particularly in the PM2. 5 fraction, we found a strong linear correlation between the dust light-absorption properties and

  4. Technical note: Aerosol light absorption measurements with a carbon analyser - Calibration and precision estimates

    NASA Astrophysics Data System (ADS)

    Ammerlaan, B. A. J.; Holzinger, R.; Jedynska, A. D.; Henzing, J. S.

    2017-09-01

    Equivalent Black Carbon (EBC) and Elemental Carbon (EC) are different mass metrics to quantify the amount of combustion aerosol. Both metrics have their own measurement technique. In state-of-the-art carbon analysers, optical measurements are used to correct for organic carbon that is not evolving because of pyrolysis. These optical measurements are sometimes used to apply the technique of absorption photometers. Here, we use the transmission measurements of our carbon analyser for simultaneous determination of the elemental carbon concentration and the absorption coefficient. We use MAAP data from the CESAR observatory, the Netherlands, to correct for aerosol-filter interactions by linking the attenuation coefficient from the carbon analyser to the absorption coefficient measured by the MAAP. Application of the calibration to an independent data set of MAAP and OC/EC observations for the same location shows that the calibration is applicable to other observation periods. Because of simultaneous measurements of light absorption properties of the aerosol and elemental carbon, variation in the mass absorption efficiency (MAE) can be studied. We further show that the absorption coefficients and MAE in this set-up are determined within a precision of 10% and 12%, respectively. The precisions could be improved to 4% and 8% when the light transmission signal in the carbon analyser is very stable.

  5. Microwave-assisted extraction (MAE) of bioactive saponin from mahogany seed (Swietenia mahogany Jacq)

    NASA Astrophysics Data System (ADS)

    Waziiroh, E.; Harijono; Kamilia, K.

    2018-03-01

    Mahogany is frequently used for medicines for cancer, tumor, and diabetes, as it contains saponin and flavonoid. Saponin is a complex glycosydic compound consisted of triterpenoids or steroids. Saponin can be extracted from a plant by using a solvent extraction. Microwave Assisted Extraction (MAE) is a non-conventional extraction method that use micro waves in the process. This research was conducted by a Complete Random Design with two factors which were extraction time (120, 150, and 180 seconds) and solvent ratio (10:1, 15:1, and 20:1 v/w). The best treatment of MAE were the solvent ratio 15:1 (v/w) for 180 seconds. The best treatment resulting crude saponin extract yield of 41.46%, containing 11.53% total saponins, and 49.17% of antioxidant activity. Meanwhile, the treatment of maceration method were the solvent ratio 20:1 (v/w) for 48 hours resulting 39.86% yield of saponin crude extract, 9.26% total saponins and 56.23% of antioxidant activity. The results showed MAE was more efficient (less time of extraction and solvent amount) than maceration method.

  6. Filter-based measurement of light absorption by brown carbon in PM2.5 in a megacity in South China.

    PubMed

    Li, Sheng; Zhu, Ming; Yang, Weiqiang; Tang, Mingjin; Huang, Xueliang; Yu, Yuegang; Fang, Hua; Yu, Xu; Yu, Qingqing; Fu, Xiaoxin; Song, Wei; Zhang, Yanli; Bi, Xinhui; Wang, Xinming

    2018-08-15

    Carbonaceous aerosols represent an important nexus between air pollution and climate change. Here we collected filter-based PM 2.5 samples during summer and autumn in 2015 at one urban and two rural sites in Guangzhou, a megacity in southern China, and got the light absorption by black carbon (BC) and brown carbon (BrC) resolved with a DRI Model 2015 multi-wavelength thermal/optical carbon analyzer apart from determining the organic carbon (OC) and elemental carbon (EC) contents. On average BrC contributed 12-15% of the measured absorption at 405nm (LA 405 ) during summer and 15-19% during autumn with significant increase in the LA 405 by BrC at the rural sites. Carbonaceous aerosols, identified as total carbon (TC), yielded average mass absorption efficiency at 405nm (MAE 405 ) that were approximately 45% higher in autumn than in summer, an 83% increase was noted in the average MAE 405 for OC, compared with an increase of only 14% in the average MAE 405 for EC. The LA 405 by BrC showed a good correlation (p<0.001) with the ratios of secondary OC to PM 2.5 in summer. However, this correlation was poor (p>0.1) in autumn, implying greater secondary formation of BrC in summer. The correlations between levoglucosan (a marker of biomass burning) and the LA 405 by BrC were significant during autumn but insignificant during summer, suggesting that the observed increase in the LA 405 by BrC during autumn in rural areas was largely related to biomass burning. The measurements of light absorption at 550nm presented in this study indicated that the use of the IMPROVE algorithm with an MAE value of 10m 2 /g for EC to approximate light absorption may be appropriate in areas not strongly affected by fossil fuel combustion; however, this practice would underestimate the absorption of light by PM 2.5 in areas heavily affected by vehicle exhausts and coal burning. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. 31 CFR 354.9 - Liability of Sallie Mae and Federal Reserve Banks.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Reserve Banks. 354.9 Section 354.9 Money and Finance: Treasury Regulations Relating to Money and Finance...-ENTRY SECURITIES OF THE STUDENT LOAN MARKETING ASSOCIATION (SALLIE MAE) § 354.9 Liability of Sallie Mae and Federal Reserve Banks. Sallie Mae and the Federal Reserve Banks may rely on the information...

  8. Quantifying black carbon light absorption enhancement with a novel statistical approach

    NASA Astrophysics Data System (ADS)

    Wu, Cheng; Wu, Dui; Zhen Yu, Jian

    2018-01-01

    Black carbon (BC) particles in the atmosphere can absorb more light when coated by non-absorbing or weakly absorbing materials during atmospheric aging, due to the lensing effect. In this study, the light absorption enhancement factor, Eabs, was quantified using a 1-year measurement of mass absorption efficiency (MAE) in the Pearl River Delta region (PRD). A new approach for calculating primary MAE (MAEp), the key for Eabs estimation, is demonstrated using the minimum R squared (MRS) method, exploring the inherent source independency between BC and its coating materials. A unique feature of Eabs estimation with the MRS approach is its insensitivity to systematic biases in elemental carbon (EC) and σabs measurements. The annual average Eabs550 is found to be 1.50 ± 0.48 (±1 SD) in the PRD region, exhibiting a clear seasonal pattern with higher values in summer and lower in winter. Elevated Eabs in the summertime is likely associated with aged air masses, predominantly of marine origin, along with long-range transport of biomass-burning-influenced air masses from Southeast Asia. Core-shell Mie simulations along with measured Eabs and absorption Ångström exponent (AAE) constraints suggest that in the PRD, the coating materials are unlikely to be dominated by brown carbon and the coating thickness is higher in the rainy season than in the dry season.

  9. Motion mechanisms with different spatiotemporal characteristics identified by an MAE technique with superimposed gratings.

    PubMed

    Shioiri, Satoshi; Matsumiya, Kazumichi

    2009-05-29

    We investigated spatiotemporal characteristics of motion mechanisms using a new type of motion aftereffect (MAE) we found. Our stimulus comprised two superimposed sinusoidal gratings with different spatial frequencies. After exposure to the moving stimulus, observers perceived the MAE in the static test in the direction opposite to that of the high spatial frequency grating even when low spatial frequency motion was perceived during adaptation. In contrast, in the flicker test, the MAE was perceived in the direction opposite to that of the low spatial frequency grating. These MAEs indicate that two different motion systems contribute to motion perception and can be isolated by using different test stimuli. Using a psychophysical technique based on the MAE, we investigated the differences between the two motion mechanisms. The results showed that the static MAE is the aftereffect of the motion system with a high spatial and low temporal frequency tuning (slow motion detector) and the flicker MAE is the aftereffect of the motion system with a low spatial and high temporal frequency tuning (fast motion detector). We also revealed that the two motion detectors differ in orientation tuning, temporal frequency tuning, and sensitivity to relative motion.

  10. Light Absorption of Black Carbon Aerosol and Its Radiative Forcing Effect in an Megacity Atmosphere in South China

    NASA Astrophysics Data System (ADS)

    Lan, Zijuan

    2013-04-01

    The effects of black carbon (BC) aerosol on climate warming have been the study focus in the recent decade, the regional effect of BC light absorption is more significant. The reduction of BC is now expected to have significant near-term climate change mitigation. Mass absorption efficient (MAE) was one of the important optical properties of BC aerosol for evaluating the BC on its radiative forcing effect, while BC mixing state is one main influencing factor for MAE. Models have estimated that BC radiative forcing can be increased by a factor of ~2 for internally versus externally mixed BC. On the other hand, some organic carbon had been found to significantly absorb light at UV or shorter wavelengths in the most recent studies, with strong spectral dependence. But large uncertainties still remain in determining the positive forcing effect of BC on global clime change due to the technical limitations. In this study, advanced instrumentation (a three-wavelength photoacoustic soot spectrometer (PASS-3) and a single particle soot photometer (SP2)) were used to measure black carbon aerosol and analyze its optical properties in a megacity in South China, Shenzhen, during the summer of 2011. It is in the southeast corner of the Pearl River Delta (PRD) region, neighboring Hong Kong to the south. During the campaign, the average BC mass concentration was 4.0±3.1 μg m-3, accounting for about 11% of PM2.5 mass concentration, which mainly came from fossil fuel combustion rather than biomass burning. The MAE of BC ranged from 5.0 to 8.5 m2 g-1, with an average value of 6.5±0.5 m2 g-1. The percentage of internally mixed BC was averagely 24.3±7.9% and positively correlated with the MAE. It is estimated that the internally mixed BC amplified MAE by about 7% during the campaign, suggesting that the BC absorption enhancement due to internal mixing in the real atmosphere is relatively low in comparison with the predictions by theoretical models, which stands in accordance with

  11. 31 CFR 354.5 - Obligations of Sallie Mae; no adverse claims.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-ENTRY SECURITIES OF THE STUDENT LOAN MARKETING ASSOCIATION (SALLIE MAE) § 354.5 Obligations of Sallie... a Federal Reserve Bank or otherwise as provided in § 354.4(c)(1), for the purposes of this part 354, Sallie Mae and the Federal Reserve Banks shall treat the Participant to whose Securities Account an...

  12. An exact algorithm for optimal MAE stack filter design.

    PubMed

    Dellamonica, Domingos; Silva, Paulo J S; Humes, Carlos; Hirata, Nina S T; Barrera, Junior

    2007-02-01

    We propose a new algorithm for optimal MAE stack filter design. It is based on three main ingredients. First, we show that the dual of the integer programming formulation of the filter design problem is a minimum cost network flow problem. Next, we present a decomposition principle that can be used to break this dual problem into smaller subproblems. Finally, we propose a specialization of the network Simplex algorithm based on column generation to solve these smaller subproblems. Using our method, we were able to efficiently solve instances of the filter problem with window size up to 25 pixels. To the best of our knowledge, this is the largest dimension for which this problem was ever solved exactly.

  13. 78 FR 21393 - Notice of Submission of Proposed Information Collection to OMB Ginnie Mae Multiclass Securities...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-10

    ..., allowing the private sector to combine and restructure cash flows from Ginnie Mae Single Class MBS into... program, Ginnie Mae guarantees, with the full faith and credit of the United States, the timely payment of... combine and restructure cash flows from Ginnie Mae Single Class MBS into securities that meet unique...

  14. Effects of landuse change on the hydrologic regime of the Mae Chaem river basin, NW Thailand

    NASA Astrophysics Data System (ADS)

    Thanapakpawin, P.; Richey, J.; Thomas, D.; Rodda, S.; Campbell, B.; Logsdon, M.

    2007-02-01

    SummaryConflicts between upland shifting cultivation, upland commercial crops, and lowland irrigated agriculture cause water resource tension in the Mae Chaem watershed in Chiang Mai, Thailand. In this paper, we assess hydrologic regimes of the Mae Chaem River with landuse change. Three plausible future forest-to-crop expansion scenarios and a scenario of crop-to-forest reversal were developed based on the landcover transition from 1989 to 2000, with emphasis on influences of elevation bands and irrigation diversion. Basin hydrologic responses were simulated using the Distributed Hydrology Soil Vegetation Model (DHSVM). Meteorological data from six weather stations inside and adjacent to the Mae Chaem watershed during the period 1993-2000 were the climate inputs. Computed stream flow was compared to observed discharge at Ban Mae Mu gauge on Mae Mu river, Ban Mae Suk gauge on Mae Suk river, and at Kaeng Ob Luang, located downstream from the district town in Mae Chaem. With current assumptions, expansion of highland crop fields led to slightly higher regulated annual and wet-season water yields compared to similar expansion in the lowland-midland zone. Actual downstream water availability was sensitive to irrigation diversion. This modeling approach can be a useful tool for water allocation for small watersheds undergoing rapid commercialization, because it alerts land managers to the potential range of water supply in wet and dry seasons, and provides information on spatial distribution of basin hydrologic components.

  15. Blackbody absorption efficiencies for six lamp pumped Nd laser materials

    NASA Technical Reports Server (NTRS)

    Cross, Patricia L.; Barnes, Norman P.; Skolaut, Milton W., Jr.; Storm, Mark E.

    1990-01-01

    Utilizing high resolution spectra, the absorption efficiencies for six Nd laser materials were calculated as functions of the effective blackbody temperature of the lamp and laser crystal size. The six materials were Nd:YAG, Nd:YLF, Nd:Q-98 Glass, Nd:YVO4, Nd:BEL, and Nd:Cr:GSGG. Under the guidelines of this study, Nd:Cr:GSGG's absorption efficiency is twice the absorption efficiency of any of the other laser materials.

  16. Sallie Mae Eyes Expansion beyond Its Charter.

    ERIC Educational Resources Information Center

    Zook, Jim

    1995-01-01

    The Student Loan Marketing Association (Sallie Mae) and the Clinton Administration are preparing legislation to transform the federally sponsored corporation into a private business but must negotiate complex political and financial issues. Destabilization of the private student-loan industry and conflict over direct-lending policies are central…

  17. Gold reflective metallic gratings with high absorption efficiency

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaojian; Liang, Linmei; Yang, Junbo

    2017-10-01

    Electromagnetic (EM) wave absorbers are devices in which the incident radiation at the operating wavelengths can be efficiently absorbed and then transformed into ohmic heat or other forms of energy. Especially, EM absorbers based on metallic structures have distinct advantages in comparison with the traditional counterparts. Thus, they have different potential applications at different frequency ranges such as absorbing devices in solar energy harvesting systems. The reflective metallic grating is a kind of metallic EM absorbers and has the fascinating property of efficiently absorbing the incident light due to the excitation of surface plasmon polaritons (SPPs), consequently drawing more and more attention. In this paper, the absorption effect of a reflective metallic grating made of gold is studied by changing grating parameters such as the period, polarization direction of the incident light and so on. We use finite difference time-domain (FDTD) method to design the grating, and simulate the process and detect the absorption spectrum. In our design, the grating has rectangular shaped grooves and has the absorption efficiency 99% for the vertically incident transverse magnetic (TM) light at the wavelength of 818nm with the period of 800 nm, the width of 365 nm and the height of 34 nm. And then we find that the absorption spectrum is blue-shifted about 87 nm with decreasing period from 800 nm to700 nm and red-shifted about 14 nm with increasing the width of the block from 305 nm to 405 nm. The absorption becomes gradually weaker from 98% to almost zero with the polarization angle from 0° to 90°. Finally, we make a theoretical explanation to these phenomena in details. It is believed that the results may provide useful guidance for the design of EM wave absorbers with high absorption efficiency.

  18. Despite a Settlement, Sallie Mae Still Plays Host to College Student-Aid Sites

    ERIC Educational Resources Information Center

    Hermes, J. J.

    2008-01-01

    Last April, as part of a $2-million settlement with New York's attorney general, the nation's largest student-loan company, Sallie Mae, agreed to stop providing staff members for colleges' financial-aid offices and call centers at no cost to the institutions. But one year later, Sallie Mae still plays host to the entire online presence for the…

  19. [Influence of electromagnetic emission at the frequencies of molecular absorption and emission spectra of oxygen and nitrogen oxide on the adhesion and formation of Pseudomonas aeruginosa biofilm].

    PubMed

    Pronina, E A; Shvidenko, I G; Shub, G M; Shapoval, O G

    2011-01-01

    Evaluate the influence of electromagnetic emission (EME) at the frequencies of molecular absorption and emission spectra of atmospheric oxygen and nitrogen oxide (MAES 02 and MAES NO respectively) on the adhesion, population progress and biofilm formation of Pseudomonas aeruginosa. Adhesive activity was evaluated by mean adhesion index (MAI) of bacteria on human erythrocytes. Population growth dynamic was assessed by optical density index of broth cultures; biofilm formation--by values of optical density of the cells attached to the surface of polystyrol wells. P.aeruginosa bacteria had high adhesive properties that have increased under the influence of MAES 02 frequency emission and have not changed under the influence of MAES NO frequency. Exposure of bacteria to MAES NO frequency did not influence the population progress; exposure to MAES 02 frequency stimulated the biofilm formation ability of the bacteria, and MAES NO--decreased this ability. EME at MAES NO frequency can be used to suppress bacterial biofilm formation by pseudomonas.

  20. Optimization of microwave assisted extraction (MAE) and soxhlet extraction of phenolic compound from licorice root.

    PubMed

    Karami, Zohreh; Emam-Djomeh, Zahra; Mirzaee, Habib Allah; Khomeiri, Morteza; Mahoonak, Alireza Sadeghi; Aydani, Emad

    2015-06-01

    In present study, response surface methodology was used to optimize extraction condition of phenolic compounds from licorice root by microwave application. Investigated factors were solvent (ethanol 80 %, methanol 80 % and water), liquid/solid ratio (10:1-25:1) and time (2-6 min). Experiments were designed according to the central composite rotatable design. The results showed that extraction conditions had significant effect on the extraction yield of phenolic compounds and antioxidant capacities. Optimal condition in microwave assisted method were ethanol 80 % as solvent, extraction time of 5-6 min and liquid/solid ratio of 12.7/1. Results were compared with those obtained by soxhlet extraction. In soxhlet extraction, Optimum conditions were extraction time of 6 h for ethanol 80 % as solvent. Value of phenolic compounds and extraction yield of licorice root in microwave assisted (MAE), and soxhlet were 47.47 mg/g and 16.38 %, 41.709 mg/g and 14.49 %, respectively. These results implied that MAE was more efficient extracting method than soxhlet.

  1. Optimization of microwave-assisted extraction (MAE) of coriander phenolic antioxidants - response surface methodology approach.

    PubMed

    Zeković, Zoran; Vladić, Jelena; Vidović, Senka; Adamović, Dušan; Pavlić, Branimir

    2016-10-01

    Microwave-assisted extraction (MAE) of polyphenols from coriander seeds was optimized by simultaneous maximization of total phenolic (TP) and total flavonoid (TF) yields, as well as maximized antioxidant activity determined by 1,1-diphenyl-2-picrylhydrazyl and reducing power assays. Box-Behnken experimental design with response surface methodology (RSM) was used for optimization of MAE. Extraction time (X1 , 15-35 min), ethanol concentration (X2 , 50-90% w/w) and irradiation power (X3 , 400-800 W) were investigated as independent variables. Experimentally obtained values of investigated responses were fitted to a second-order polynomial model, and multiple regression analysis and analysis of variance were used to determine fitness of the model and optimal conditions. The optimal MAE conditions for simultaneous maximization of polyphenol yield and increased antioxidant activity were an extraction time of 19 min, an ethanol concentration of 63% and an irradiation power of 570 W, while predicted values of TP, TF, IC50 and EC50 at optimal MAE conditions were 311.23 mg gallic acid equivalent per 100 g dry weight (DW), 213.66 mg catechin equivalent per 100 g DW, 0.0315 mg mL(-1) and 0.1311 mg mL(-1) respectively. RSM was successfully used for multi-response optimization of coriander seed polyphenols. Comparison of optimized MAE with conventional extraction techniques confirmed that MAE provides significantly higher polyphenol yields and extracts with increased antioxidant activity. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  2. 77 FR 74022 - Notice of Proposed Information Collection: Comment Request; Ginnie Mae Mortgage-Backed Securities...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-12

    ... multiple Issuer MBS is structured so that small issuers, who do not meet the minimum number of loans and... program, securities are backed by single-family or multifamily loans. Under the Ginnie Mae II program, securities are only backed by single family loans. Both the Ginnie Mae I and II MBS are modified pass-through...

  3. 75 FR 44804 - Privacy Act of 1974; Notice of a New Privacy Act System of Records (SORN), Ginnie Mae Mortgage...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ...The Department proposes to establish a new Privacy Act SORN subject to the Privacy Act of 1974 (5 U.S.C. 552a), as amended, entitled Ginnie Mae Mortgage-Backed Security Unclaimed Funds System. The new record system will be used to track unclaimed security holder payments. Such unclaimed payments are owed to certificate holders of Ginnie Mae-guaranteed mortgage-backed securities who cannot be located by the Ginnie Mae servicer. Ginnie Mae tracks this information to ensure that security holders are paid properly.

  4. 31 CFR 354.7 - Withdrawal of eligible Book-entry Sallie Mae Securities for conversion to definitive form.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 2 2011-07-01 2011-07-01 false Withdrawal of eligible Book-entry... PUBLIC DEBT REGULATIONS GOVERNING BOOK-ENTRY SECURITIES OF THE STUDENT LOAN MARKETING ASSOCIATION (SALLIE MAE) § 354.7 Withdrawal of eligible Book-entry Sallie Mae Securities for conversion to definitive form...

  5. 24 CFR 350.8 - Withdrawal of Eligible Book-entry Ginnie Mae Securities for Conversion to Definitive Form.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 2 2012-04-01 2012-04-01 false Withdrawal of Eligible Book-entry... ASSOCIATION, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.8 Withdrawal of Eligible Book-entry Ginnie Mae Securities for Conversion to Definitive Form. (a) Eligible book-entry Ginnie Mae...

  6. 24 CFR 350.8 - Withdrawal of Eligible Book-entry Ginnie Mae Securities for Conversion to Definitive Form.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 2 2013-04-01 2013-04-01 false Withdrawal of Eligible Book-entry... ASSOCIATION, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.8 Withdrawal of Eligible Book-entry Ginnie Mae Securities for Conversion to Definitive Form. (a) Eligible book-entry Ginnie Mae...

  7. A benchmarking method to measure dietary absorption efficiency of chemicals by fish.

    PubMed

    Xiao, Ruiyang; Adolfsson-Erici, Margaretha; Åkerman, Gun; McLachlan, Michael S; MacLeod, Matthew

    2013-12-01

    Understanding the dietary absorption efficiency of chemicals in the gastrointestinal tract of fish is important from both a scientific and a regulatory point of view. However, reported fish absorption efficiencies for well-studied chemicals are highly variable. In the present study, the authors developed and exploited an internal chemical benchmarking method that has the potential to reduce uncertainty and variability and, thus, to improve the precision of measurements of fish absorption efficiency. The authors applied the benchmarking method to measure the gross absorption efficiency for 15 chemicals with a wide range of physicochemical properties and structures. They selected 2,2',5,6'-tetrachlorobiphenyl (PCB53) and decabromodiphenyl ethane as absorbable and nonabsorbable benchmarks, respectively. Quantities of chemicals determined in fish were benchmarked to the fraction of PCB53 recovered in fish, and quantities of chemicals determined in feces were benchmarked to the fraction of decabromodiphenyl ethane recovered in feces. The performance of the benchmarking procedure was evaluated based on the recovery of the test chemicals and precision of absorption efficiency from repeated tests. Benchmarking did not improve the precision of the measurements; after benchmarking, however, the median recovery for 15 chemicals was 106%, and variability of recoveries was reduced compared with before benchmarking, suggesting that benchmarking could account for incomplete extraction of chemical in fish and incomplete collection of feces from different tests. © 2013 SETAC.

  8. Optical absorption characteristics of brown carbon aerosols during the KORUS-AQ campaign at an urban site

    NASA Astrophysics Data System (ADS)

    Park, Seungshik; Yu, Geun-Hye; Lee, Sangil

    2018-05-01

    This study investigates the absorption characteristics of brown carbon (BrC) obtained from water and methanol extracts of fine particulate matter measured at an urban site in Gwangju, Korea during the KOREA U.S. - Air Quality campaign (May 2-June 11, 2016). The measurement period was classified into two intervals: biomass burning (BB) and non-BB periods. During the non-BB period, water-soluble organic carbon (WSOC) and humic-like substances (HULIS) primarily resulted from secondary organic aerosol (SOA) formation and primary vehicle emissions. Water-soluble organic aerosols during the BB period, meanwhile, were closely related to SOA formation and regionally transported BB emissions. The light absorption coefficient measured at 365 nm (babs,365) by methanol extracts was 2.6 and 6.1 times higher than the coefficients from the water and HULIS extracts, respectively, indicating the importance of BrC absorption by water-insoluble organic carbon. This was demonstrated by a good correlation between the water-insoluble BrC absorption and the elemental carbon concentration. A comparison of babs,365 between the methanol- and water-extracted BrC indicated that water-insoluble BrC accounted for approximately 61% (33-86%) of the total BrC absorption. The contributions of SOA, primary BB emissions, and traffic emissions to the water extract babs,365 were estimated using a stepwise multiple linear regression (MLR) analysis and found to be 1.17 ± 0.55, 0.65 ± 0.62, and 0.25 ± 0.09 Mm- 1, respectively, accounting for 59.6, 26.1, and 14.3% of the absorption coefficient by the water-soluble BrC. Further, it was determined that the contribution of the BB emissions to the water-soluble BrC absorption was approximately two times higher in the BB period than in the non-BB period. The average absorption Ångstrӧm exponent was 4.8 ± 0.3, 5.3 ± 0.7, and 6.8 ± 0.8 for the methanol, water, and HULIS extracts, respectively. The average mass absorption efficiency (MAE365) of methanol

  9. Determination of Magneto-crystalline Anisotropy Energy (MAE) Of ordered L10 CoPt and FePt nanoparticles

    NASA Astrophysics Data System (ADS)

    Alsaad, A.; Ahmad, A. A.; Shukri, A. A.; Bani-Younes, O. A.

    2018-02-01

    The structural and magnetic properties of both L10 ordered FePt and CoPt nanoparticles make them potential candidates for optical-electronic and magneto-optical devices. First, we carried out an ab initio total energy minimization study to find the geometrical optimization of both L10 phases of FePt and CoPt nanoparticles. Then, we investigated the magnetocrystalline anisotropy energy (MAE) of both systems along special line joining the points of high symmetry (A,B and C points) using super-cell slap approach with alternating layers Fe/Co and Pt along the (001) direction. We found that the point (A) has the highest MAE value for both systems, where the value of MAE in FePt is 8.89 × 107 erg/cm3 and in CoPt is 6.40 × 107 erg/cm3. Our spin density based calculations indicate that large spin-orbit interaction and the hybridization between Pt 5d states and Fe/Co 3d states are the dominant factors in determining the MAE in both systems.

  10. African-American Soul Force: Dance, Music and Vera Mae Green.

    ERIC Educational Resources Information Center

    Bolles, A. Lynn

    1986-01-01

    The Black anthropologist, Vera Mae Green, is featured in this analysis of the concept of soul as applied to African-Americans. Music and dance are used to express soul in cultural context. But soul is also a force, an energy which encompasses the Black experience and makes Black culture persevere. (VM)

  11. 78 FR 77450 - Fannie Mae and Freddie Mac Loan Purchase Limits: Request for Public Input on Implementation Issues

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-23

    ... reductions in Freddie Mac's and Fannie Mae's loan purchase limits. In short, no final decision on loan... decision to direct the setting of new and lower loan purchase limits by the Enterprises. A Plan for Setting... FEDERAL HOUSING FINANCE AGENCY [No. 2013-N-18] Fannie Mae and Freddie Mac Loan Purchase Limits...

  12. Efficiency of the High Efficiency Total Absorption Spectrometer (HECTOR)

    NASA Astrophysics Data System (ADS)

    Sprowal, Zaire; Simon, Anna; Reingold, Craig; Spyrou, Artemis; Naqvi, Farheen; Dombos, Alexander; Palmisano, Alicia; Anderson, Tyler; Anderson, Samuel; Moylan, Shane; Seymour, Christopher; Skulski, Michael; Smith, Mallory K.; Strauss, Sabrina; Kolk, Byant Vande

    2016-09-01

    The p-process is a nucleosynthesis process that occurs in explosive environments such as type II and Ia supernovae and is responsible for production of heavy proton rich nuclei. Gamma rays emitted during these explosions induce several photo-disintegration reactions: (γ,n), (γ,p), and (γ , α). To study these interactions, the inverse of these reactions are measured experimentally. The High Efficiency TOtal absorption spectrometeR (HECTOR) at the University of Notre Dame was built for measuring these reactions. Standard gamma sources 60Co and 137Cs and known resonances in 27Al(p, γ)28Si reaction were used to experimentally determine HECTOR's summing efficiency. Here, the preliminary analysis will be presented and the results will be compared to the Geant4 simulation of the array. This work was supported by the National Science Foundation under the Grant Number PHYS-1614442.

  13. Sources, composition and absorption Ångström exponent of light-absorbing organic components in aerosol extracts from the Los Angeles Basin.

    PubMed

    Zhang, Xiaolu; Lin, Ying-Hsuan; Surratt, Jason D; Weber, Rodney J

    2013-04-16

    We investigate the sources, chemical composition, and spectral properties of light-absorbing organic aerosol extracts (i.e., brown carbon, or BrC) in the Los Angeles (LA) Basin during the CalNex-2010 field campaign. Light absorption of PM2.5 water-soluble components at 365 nm (Abs365), used as a proxy for water-soluble BrC, was well correlated with water-soluble organic carbon (WSOC) (r(2) = 0.55-0.65), indicating secondary organic aerosol (SOA) formation from anthropogenic emissions was the major source of water-soluble BrC in this region. Normalizing Abs365 to WSOC mass yielded an average solution mass absorption efficiency (MAE365) of 0.71 m(2) g(-1) C. Detailed chemical speciation of filter extracts identified eight nitro-aromatic compounds that were correlated with Abs365. These compounds accounted for ∼4% of the overall water-soluble BrC absorption. Methanol-extracted BrC in LA was approximately 3 and 21 times higher than water-soluble BrC at 365 and 532 nm, respectively, and had a MAE365 of 1.58 m(2) g(-1) C (Abs365 normalized to organic carbon mass). The water-insoluble BrC was strongly correlated with ambient elemental carbon concentration, suggesting similar sources. Absorption Ångström exponent (Å(a)) (fitted between 300 and 600 nm wavelengths) was 3.2 (±1.2) for the PILS water-soluble BrC measurement, compared to 4.8 (±0.5) and 7.6 (±0.5) for methanol- and water-soluble BrC from filter extracts, respectively. These results show that fine particle BrC was prevalent in the LA basin during CalNex, yet many of its properties and potential impacts remain unknown.

  14. Palynology and organic/isotope geochemistry of the Mae Moh Basin, Northern Thailand

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

    Minh, L.V.; Abrajano, T.; Burden, E.

    The Mae Moh basin is one of several Tertiary intermontane basins in northern Thailand, whose evolution has been linked to the collision of the Indian plate with the Eurasian plate since the early Eocene. As in most of these basins, lacustrine/swamp sedimentation in the Mae Moh basin can be broadly divided into an Oligocene to Miocene synrift sequence and a Miocene to Quarternary postrift sequence. The dominance of swamp flora recognized from spore and pollen assemblages (e.g., Polypodiidites usmensis, Verrucatosporites, Cyrtostachys), as well as the abundance of macrophytes and woody debris, indicate overwhelming hot and humid swamp conditions, with lakemore » development restricted to relatively small areas. The distribution of alkanes and their compound-specific carbon isotope compositions are used to further show climatic variations affecting the lake/swamp ecology during the deposition of the synrift sequence.« less

  15. Experiments on the applicability of MAE techniques for predicting sound diffraction by irregular terrains. [Matched Asymptotic Expansion

    NASA Technical Reports Server (NTRS)

    Berthelot, Yves H.; Pierce, Allan D.; Kearns, James A.

    1987-01-01

    The sound field diffracted by a single smooth hill of finite impedance is studied both analytically, within the context of the theory of Matched Asymptotic Expansions (MAE), and experimentally, under laboratory scale modeling conditions. Special attention is given to the sound field on the diffracting surface and throughout the transition region between the illuminated and the shadow zones. The MAE theory yields integral equations that are amenable to numerical computations. Experimental results are obtained with a spark source producing a pulse of 42 microsec duration and about 130 Pa at 1 m. The insertion loss of the hill is inferred from measurements of the acoustic signals at two locations in the field, with subsequent Fourier analysis on an IBM PC/AT. In general, experimental results support the predictions of the MAE theory, and provide a basis for the analysis of more complicated geometries.

  16. Modified thermal-optical analysis using spectral absorption selectivity to distinguish black carbon from pyrolized organic carbon.

    PubMed

    Hadley, Odelle L; Corrigan, Craig E; Kirchstetter, Thomas W

    2008-11-15

    This study presents a method for analyzing the black carbon (BC) mass loading on a quartz fiber filter using a modified thermal-optical analysis method, wherein light transmitted through the sample is measured over a spectral region instead of at a single wavelength. Evolution of the spectral light transmission signal depends on the relative amounts of light-absorbing BC and char, the latter of which forms when organic carbon in the sample pyrolyzes during heating. Absorption selectivities of BC and char are found to be distinct and are used to apportion the amount of light attenuated by each component in the sample. Light attenuation is converted to mass concentration on the basis of derived mass attenuation efficiencies (MAEs) of BC and char. The fractions of attenuation due to each component are scaled by their individual MAE values and added together as the total mass of light absorbing carbon (LAC). An iterative algorithm is used to find the MAE values for both BC and char that provide the best fit to the carbon mass remaining on the filter (derived from direct measurements of thermally evolved CO2) at temperatures higher than 480 degrees C. This method was applied to measure the BC concentration in precipitation samples collected in northern California. The uncertainty in the measured BC concentration of samples that contained a high concentration of organics susceptible to char ranged from 12% to 100%, depending on the mass loading of BC on the filter. The lower detection limit for this method was approximately 0.35 microg of BC, and the uncertainty approached 20% for BC mass loading greater than 1.0 microg of BC.

  17. Cell openness manipulation of low density polyurethane foam for efficient sound absorption

    NASA Astrophysics Data System (ADS)

    Hyuk Park, Ju; Suh Minn, Kyung; Rae Lee, Hyeong; Hyun Yang, Sei; Bin Yu, Cheng; Yeol Pak, Seong; Sung Oh, Chi; Seok Song, Young; June Kang, Yeon; Ryoun Youn, Jae

    2017-10-01

    Satisfactory sound absorption using a low mass density foam is an intriguing desire for achieving high fuel efficiency of vehicles. This issue has been dealt with a microcellular geometry manipulation. In this study, we demonstrate the relationship between cell openness of polyurethane (PU) foam and sound absorption behaviors, both theoretically and experimentally. The objective of this work is to mitigate a threshold of mass density by rendering a sound absorber which shows a satisfactory performance. The cell openness, which causes the best sound absorption performance in all cases considered, was estimated as 15% by numerical simulation. Cell openness of PU foam was experimentally manipulated into desired ranges by adjusting rheological properties in a foaming reaction. Microcellular structures of the fabricated PU foams were observed and sound absorption coefficients were measured using a B&K impedance tube. The fabricated PU foam with the best cell openness showed better sound absorption performance than the foam with double mass density. We envisage that this study can help the manufacture of low mass density sound absorbing foams more efficiently and economically.

  18. Light Absorption and Excitation-Emission Fluorescence of Urban Organic Aerosol Components and Their Relationship to Chemical Structure.

    PubMed

    Chen, Qingcai; Ikemori, Fumikazu; Mochida, Michihiro

    2016-10-18

    The present study used a combination of solvent and solid-phase extractions to fractionate organic compounds with different polarities from total suspended particulates in Nagoya, Japan, and their optical characteristics were obtained on the basis of their UV-visible absorption spectra and excitation-emission matrices (EEMs). The relationship between their optical characteristics and chemical structures was investigated based on high-resolution aerosol mass spectra (HR-AMS spectra), soft ionization mass spectra and Fourier transform infrared (FT-IR) spectra. The major light-absorption organics were less polar organic fractions, which tended to have higher mass absorption efficiencies (MAEs) and lower wavelength dependent Ångström exponents (Å) than the more polar organic fractions. Correlation analyses indicate that organic compounds with O and N atoms may contribute largely to the total light absorption and fluorescence of the organic aerosol components. The extracts from the aerosol samples were further characterized by a classification of the EEM profiles using a PARAFAC model. Different fluorescence components in the aerosol organic EEMs were associated with specific AMS ions and with different functional groups from the FT-IR analysis. These results may be useful to determine and further classify the chromophores in atmospheric organic aerosols using EEM spectroscopy.

  19. Sorption characteristics of cadmium in a clay soil of Mae Ku creek, Tak Province, Thailand

    NASA Astrophysics Data System (ADS)

    Thunyawatcharakul, P.; Chotpantarat, S.

    2018-05-01

    Mae Sot is a district in Tak province, the northern part of Thailand where has encountered with cadmium (Cd) contaminated in soils. Exposure of Cd can lead to severe health effect, for examples, bone softening, osteoporosis, renal dysfunction, and Itai-Itai disease. This study aims at elucidating sorption behavior of Cd in the contaminated soil collected from Mae Ku creek, Mae Sot district, Thailand. Batch sorption experiment was conducted in order to investigate sorption characteristics of Cd onto the contaminated soil. The soil sample taken from the study area consists of 26% sand, 16% silt 58% clay, which categorized as a clay soil, based on USDA classification. Soil pH is slightly alkaline (pH∼7.7) and organic matter in the soil is 2.93%. The initial concentration in the batch sorption experiment was in the range from 0- 200 ppm. The result from the batch sorption experiment showed that soil sample can adsorb Cd up to 173.5 ppm and the sorption behavior of the soil sample can be well described by Freundlich isotherm, indicating the multilayer sorption (R2 = 0.9964), with Freundlich constants of 0.312 and 1.760 L g-1 for 1/n and Kf, respectively.

  20. [Aquatic Ecological Index based on freshwater (ICE(RN-MAE)) for the Rio Negro watershed, Colombia].

    PubMed

    Forero, Laura Cristina; Longo, Magnolia; John Jairo, Ramirez; Guillermo, Chalar

    2014-04-01

    Aquatic Ecological Index based on freshwater (ICE(RN-MAE)) for the Rio Negro watershed, Colombia. Available indices to assess the ecological status of rivers in Colombia are mostly based on subjective hypotheses about macroinvertebrate tolerance to pollution, which have important limitations. Here we present the application of a method to establish an index of ecological quality for lotic systems in Colombia. The index, based on macroinvertebrate abundance and physicochemical variables, was developed as an alternative to the BMWP-Col index. The method consists on determining an environmental gradient from correlations between physicochemical variables and abundance. The scores obtained in each sampling point are used in a standardized correlation for a model of weighted averages (WA). In the WA model abundances are also weighted to estimate the optimum and tolerance values of each taxon; using this information we estimated the index of ecological quality based also on macroinvertebrate (ICE(RN-MAE)) abundance in each sampling site. Subsequently, we classified all sites using the index and concentrations of total phosphorus (TP) in a cluster analysis. Using TP and ICE(RN-MAE), mean, maximum, minimum and standard deviation, we defined threshold values corresponding to three categories of ecological status: good, fair and critical.

  1. Temperature Variability Associated with the Middle Atmosphere Electrodynamics (MAE-1) Campaign

    NASA Technical Reports Server (NTRS)

    Schmidlin, F. J.

    1999-01-01

    Meteorological rockets launched during the Middle Atmosphere Electrodynamics (MAE-1) Campaign in October 1980 from Andoya Rocket Range (ARR), Norway, exhibited large and unexpected temperature variability. Temperatures were found to vary as much as 20 C within a few hours and demonstrated a similar type of variability from one day to the next. Following examination of the reduced rocketsonde profiles the question was raised whether the observed variability was due to natural atmospheric variability or instrument malfunction. Small-scale variability, as observed, may result from one or multiple sources, e.g., intense storms upstream from the observing site, orography such as mountain waves off of the Greenland Plateau, convective activity, gravity waves, etc. Arranging the observations spaced over time showed that the perturbations moved downward. Prior to MAE-1 very few small rocketsonde measurements had been launched from ARR, thus the quality of the initial measurements in early October caused concern when the large variability was noted. We discuss the errors of the rocketsonde measurements, graphically review the nature of the variability observed, compare the data with other measurements, and postulate a possible cause for the variability.

  2. Ingestion Rates and Absorption Efficiencies of Abra ovata(Mollusca: Bivalvia) Fed on Macrophytobenthic Detritus

    NASA Astrophysics Data System (ADS)

    Charles, F.; Grémare, A.; Amouroux, J. M.

    1996-01-01

    Ingestion and absorption were investigated in the deposit-feeding bivalve Abra ovatafed on 14C-formaldehyde-labelled detritus derived from 11 macrophytes: Posidonia oceanica, Cystoseira compressa, Padina pavonica, Stypocaulon scoparium, Colpomenia sinuosa, Cystoseira mediterranea, Dilophus spiralis, Rissoella verruculosa, Ulva rigida, Corallina elongata andCodium vermilara . Labelling efficiency ranged from 3·2 (R. verruculosa ) to 53·0% (C. sinuosa) depending on the detritus. The stability of the labelling also varied among detritus types, and was negatively correlated with labelling efficiency. For all types of detritus, the exchanges of radioactivity between compartments were dominated by the transfer between particulate organic matter (POM) and bivalves. These transfers resulted from the interactions between the processes of ingestion, defaecation, and recycling of faeces. The coexistence of these processes together with the occasional lack of stability of the label complicated the actual determination of ingestion rates and absorption efficiencies, which necessitated the use of mathematical modelling. The model was initially composed of five compartments: Detritus, Bivalves, Dissolved organic matter (DOM), CO 2, and Faeces. Two first-order time delays were introduced to account for the production of faeces and CO 2by the bivalves. These delays resulted in the subdivision of the Bivalves compartment into three subcompartments: bivIng, bivDig, and bivAbs. The model also accounts for differences in utilization rates of detritus and faeces by the bivalves. It simulates the exchange of radioactivity between compartments and allows the quantification of ingestion and absorption efficiencies. Our results show large differences in both ingestion rates and absorption efficiencies of A. ovatafed on different types of detritus. Ingestion rates ranged between 0·16 ( C. mediterraneaand D. spiralis) and 8·65 μgOM mgDW -1 h -1( U. rigida). Absorption efficiencies ranged

  3. 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.

  4. Measuring teachers' knowledge of attention deficit hyperactivity disorder: the MAE-TDAH Questionnaire.

    PubMed

    Soroa, Marian; Balluerka, Nekane; Gorostiaga, Arantxa

    2014-10-28

    The lack of methodological rigor is frequent in most of instruments developed to assess the knowledge of teachers regarding Attention Deficit Hyperactivity Disorder (ADHD). The aim of this study was to develop a questionnaire, namely Questionnaire for the evaluation of teachers' knowledge of ADHD (MAE-TDAH), for measuring the level of knowledge about ADHD of infant and primary school teachers. A random sample of 526 teachers from 57 schools in the Autonomous Community of the Basque Country and Navarre was used for the analysis of the psychometric properties of the instrument. The participant teachers age range was between 22 and 65 (M = 42.59; SD = 10.89), and there were both generalist and specialized teachers. The measure showed a 4 factor structure (Etiology of ADHD, Symptoms/Diagnosis of ADHD, General information about ADHD and Treatment of ADHD) with adequate internal consistency (Omega values ranged between .83 and .91) and temporal stability indices (Spearman's Rho correlation values ranged between .62 and .79). Furthermore, evidence of convergent and external validity was obtained. Results suggest that the MAE-TDAH is a valid and reliable measure when it comes to evaluating teachers' level of knowledge of ADHD.

  5. Efficient Algorithms for Estimating the Absorption Spectrum within Linear Response TDDFT

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

    Brabec, Jiri; Lin, Lin; Shao, Meiyue

    We present two iterative algorithms for approximating the absorption spectrum of molecules within linear response of time-dependent density functional theory (TDDFT) framework. These methods do not attempt to compute eigenvalues or eigenvectors of the linear response matrix. They are designed to approximate the absorption spectrum as a function directly. They take advantage of the special structure of the linear response matrix. Neither method requires the linear response matrix to be constructed explicitly. They only require a procedure that performs the multiplication of the linear response matrix with a vector. These methods can also be easily modified to efficiently estimate themore » density of states (DOS) of the linear response matrix without computing the eigenvalues of this matrix. We show by computational experiments that the methods proposed in this paper can be much more efficient than methods that are based on the exact diagonalization of the linear response matrix. We show that they can also be more efficient than real-time TDDFT simulations. We compare the pros and cons of these methods in terms of their accuracy as well as their computational and storage cost.« less

  6. Nonuniform Effect of Carrier Separation Efficiency and Light Absorption in Type-II Perovskite Nanowire Solar Cells

    NASA Astrophysics Data System (ADS)

    Wang, Weiping; He, Jialun; Cao, Yiyan; Kong, Lijing; Zheng, Xuanli; Wu, Yaping; Chen, Xiaohong; Li, Shuping; Wu, Zhiming; Kang, Junyong

    2017-03-01

    Coaxial structures exhibit great potential for the application of high-efficiency solar cells due to the novel mechanism of radial charge separation. Here, we intensively investigate the nonuniform effect of carrier separation efficiency (CSE) and light absorption in perovskite-based type-II coaxial nanowire solar cells (ZnO/CH3NH3PbI3). Results show that the CSE rapidly decreases along the radial direction in the shell, and the value at the outer side becomes extremely low for the thick shell. Besides, the position of the main light absorption gradually moves to the outer side with the increase of the shell thickness. As a result, the external quantum efficiency shows a positional dependence with a maximal value close to the border of the nanowire. Eventually, in our case, it is found that the maximal power conversion efficiency of the solar cells reduces from 19.5 to 17.9% under the effect of the nonuniformity of CSE and light absorption. This work provides a basis for the design of high-efficiency solar cells, especially type-II nanowire solar cells.

  7. Nonuniform Effect of Carrier Separation Efficiency and Light Absorption in Type-II Perovskite Nanowire Solar Cells.

    PubMed

    Wang, Weiping; He, Jialun; Cao, Yiyan; Kong, Lijing; Zheng, Xuanli; Wu, Yaping; Chen, Xiaohong; Li, Shuping; Wu, Zhiming; Kang, Junyong

    2017-12-01

    Coaxial structures exhibit great potential for the application of high-efficiency solar cells due to the novel mechanism of radial charge separation. Here, we intensively investigate the nonuniform effect of carrier separation efficiency (CSE) and light absorption in perovskite-based type-II coaxial nanowire solar cells (ZnO/CH 3 NH 3 PbI 3 ). Results show that the CSE rapidly decreases along the radial direction in the shell, and the value at the outer side becomes extremely low for the thick shell. Besides, the position of the main light absorption gradually moves to the outer side with the increase of the shell thickness. As a result, the external quantum efficiency shows a positional dependence with a maximal value close to the border of the nanowire. Eventually, in our case, it is found that the maximal power conversion efficiency of the solar cells reduces from 19.5 to 17.9% under the effect of the nonuniformity of CSE and light absorption. This work provides a basis for the design of high-efficiency solar cells, especially type-II nanowire solar cells.

  8. Comparing the enhancement efficiency between liposomes and microbubbles for insulin pulmonary absorption.

    PubMed

    Xu, Yan-Yan; Lu, Cui-Tao; Fu, Hong-Xing; Zhao, Ying-Zheng; Yang, Wei; Li, Xing; Zhang, Lu; Li, Xiao-Kun; Zhang, Ming

    2011-07-01

    The present study investigated the enhancement efficiency between liposomes and microbubbles for insulin pulmonary absorption. Two types of phospholipid-based vesicle-liposomes and microbubbles-were prepared, and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cytotoxicity test was used to evaluate their in vitro toxicity in A549 cells. Cellular uptake of insulin combined with liposomes or microbubbles was determined using A549 cells. With intratracheal insufflation of Sprague-Dawley rats, an insulin mixture with liposomes or microbubbles was administered to assess its potential for promoting drug pulmonary absorption. Both liposomes and microbubbles had a narrow and monodispersed size distribution with average diameter of 3.1 μm and 1.0 μm, respectively. From the MTT cytotoxicity test, a phospholipid-based vesicle concentration of <25% (vol/vol) in the final volume was the safe dosage range that could avoid severe cytotoxic effects. The intracellular uptake amount of insulin in the insulin-microbubble mixture was significantly higher than that in the insulin-liposome mixture. The minimum reductions of the blood glucose concentration produced by insulin-microbubble and insulin-liposome mixtures were 60.8% and 35.0% of the initial glucose levels, respectively, and their bioavailabilities relative to subcutaneous injection were 48.6% and 30.8%, respectively. Microbubbles have much better efficiency than liposomes in the rate and extent of insulin pulmonary absorption. Microbubbles might be recommended as a potential agent for enhancing protein intrapulmonary absorption.

  9. Efficient Sub-Bandgap Light Absorption and Signal Amplification in Silicon Photodetectors

    NASA Astrophysics Data System (ADS)

    Liu, Yu-Hsin

    This thesis focuses on two areas in silicon photodetectors, the first being enhancing the sub-bandgap light absorption of IR wavelenghts in silicon, and the second being intrinsic signal amplification in silicon photodetectors. Both of these are achieved using heavily doped p-n junction devices which create localized states that relax the k-selection rule of indirect bandgap material. The probability of transitions between impurity band and the conduction/valence band would be much more efficient than the one between band-to-band transition. The waveguide-coupled epitaxial p-n photodetector was demonstrated for 1310 nm wavelength detection. Incorporated with the Franz-Keldysh effect and the quasi-confined epitaxial layer design, an absorption coefficient around 10 cm-1 has been measured and internal quantum efficiency nearly 100% at -2.5V. The absorption coefficient is calculated from the wave function of the electron and hole in p-n diode. The heavily doped impurity wave function can be formulated as a delta function, and the quasi-confined conduction band energy states, and the wave function on each level can be obtained from the Silvaco software. The calculated theoretical absorption coefficient increases with the increasing applied bias and the doping concentration, which matches the experimental results. To solve the issues of large excess noise and high operation bias for avalanche photodiodes based on impact ionization, I presented a detector using the Cycling Excitation Process (CEP) for signal amplification. This can be realized in a heavily doped and highly compensated Si p-n junction, showing ultra high gain about 3000 at very low bias (<4 V), and possessing an intrinsic, phonon-mediated regulation process to keep the device stable without any quenching device required in today's Geiger-mode avalanche detectors. The CEP can be formulated with the rate equations in conduction bands and impurity states. The gain expression, which is a function of the

  10. Radiative Absorption by Light Absorbing Carbon: Uncertainty, Temporal and Spatial Variation in a Typical Polluted City in Yangtze River Delta

    NASA Astrophysics Data System (ADS)

    Chen, D.; Zhao, Y.; Lyu, R.

    2017-12-01

    The optical properties of light absorbing carbon (LAC) in atmospheric aerosols, including their uncertainties, temporal change and spatial pattern were studied at suburban, urban and industrial sites in Nanjing, a typical polluted city in Yangtze River Delta (YRD). The optical properties of black carbon (BC) and the uncertainty in radiative absorption of BC were quantified combining cavity attenuated phase shift (CAPS) and thermal-optical techniques. It was found that applying a constant value from previous studies for multiple scattering factor could not well represent the actual absorption characteristics of aerosols in Nanjing. The relative deviation between calculated and measured absorption coefficient of BC was up to 56 ± 34%. A significant positive correlation (R2=0.95) was found between multiple scattering factor (C*) and the mixing state of EC (ECopt/EC) within the ECopt/EC ranged 0.43 0.92 (C*=1.64(ECopt/EC)+1.47, 0.43opt/EC<0.57; C*=6.42(ECopt/EC)-1.39, 0.57opt/EC<0.92). However, C* were not linearly correlated with ECopt/EC when the ratios were below 0.43 or above 0.92. The content of isoprene from biogenic volatile organic compounds (BVOCs) was higher in summer (5.8%) than that in autumn (0.5%). Brown carbon (BrC) associated with anthropogenic precursors was stronger in light absorption than that from biogenic sources, thus precursors of secondary organic aerosol (SOA) was probably the main reason for seasonal variation in MAE of BrC. At industrial site, linear positive correlation (R=0.87) was found between measured MSOC and secondary organic carbon (SOC), suggesting SOA formation was the major source of MSOC in this area. The lower MAE values of MSOC indicated that BrC generated from secondary sources might demonstrate weaker light absorbing ability than that from primary emissions. Furthermore, quantitative analysis showed that MAE BrC, 365 reduced by 0.26 m2/g when SOC increased by 1μgC/m3. This study provided insights into a more comprehensive

  11. How America Pays for College, 2014: Sallie Mae's National Study of College Students and Parents

    ERIC Educational Resources Information Center

    Sallie Mae, Inc., 2014

    2014-01-01

    Sallie Mae has conducted "How America Pays for College" annually since 2008, providing information about the resources American families invest in an undergraduate college education. This study focuses particularly on the planning and payment behaviors in a given academic year. Now in its seventh year, the study provides a compelling…

  12. Elastic properties and optical absorption studies of mixed alkali borogermanate glasses

    NASA Astrophysics Data System (ADS)

    Taqiullah, S. M.; Ahmmad, Shaik Kareem; Samee, M. A.; Rahman, Syed

    2018-05-01

    First time the mixed alkali effect (MAE) has been investigated in the glass system xNa2O-(30-x)Li2O-40B2O3- 30GeO2 (0≤x≤30 mol%) through density and optical absorption studies. The present glasses were prepared by melt quench technique. The density of the present glasses varies non-linearly exhibiting mixed alkali effect. Using the density data, the elastic moduli namely Young's modulus, bulk and shear modulus show strong linear dependence as a function of compositional parameter. From the absorption edge studies, the values of optical band gap energies for all transitions have been evaluated. It was established that the type of electronic transition in the present glass system is indirect allowed. The indirect optical band gap exhibit non-linear behavior with compositional parameter showing the mixed alkali effect.

  13. 24 CFR 350.11 - Notice of Attachment for Ginnie Mae Securities in Book-entry System.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Securities in Book-entry System. 350.11 Section 350.11 Housing and Urban Development Regulations Relating to... AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.11 Notice of Attachment for Ginnie Mae Securities in Book-entry System. The interest of a debtor in a Security Entitlement may be reached by a creditor only...

  14. 24 CFR 350.11 - Notice of Attachment for Ginnie Mae Securities in Book-entry System.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Securities in Book-entry System. 350.11 Section 350.11 Housing and Urban Development Regulations Relating to... AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.11 Notice of Attachment for Ginnie Mae Securities in Book-entry System. The interest of a debtor in a Security Entitlement may be reached by a creditor only...

  15. 24 CFR 350.11 - Notice of Attachment for Ginnie Mae Securities in Book-entry System.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Securities in Book-entry System. 350.11 Section 350.11 Housing and Urban Development Regulations Relating to... AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.11 Notice of Attachment for Ginnie Mae Securities in Book-entry System. The interest of a debtor in a Security Entitlement may be reached by a creditor only...

  16. How America Pays for College, 2009. Sallie Mae's National Study of College Students and Parents

    ERIC Educational Resources Information Center

    Sallie Mae, Inc., 2009

    2009-01-01

    Sallie Mae's study, "How America Pays for College 2009," conducted by Gallup, provides a picture of how families made the investment in higher education last academic year and how they are beginning to meet the challenges of the economic recession. Based on a nationally representative survey of college-going students and parents of undergraduates,…

  17. How America Pays for College, 2010. Sallie Mae's National Study of College Students and Parents

    ERIC Educational Resources Information Center

    Sallie Mae, Inc., 2010

    2010-01-01

    This report presents the findings of a quantitative survey research program that Gallup, Inc. conducted on behalf of Sallie Mae. The overall objective of the study was to determine how American families are paying for higher education. The study also measures public attitudes toward college and various topics related to funding college. To achieve…

  18. How America Saves for College, 2009. Sallie Mae's National Study of College Students and Parents

    ERIC Educational Resources Information Center

    Sallie Mae, Inc., 2009

    2009-01-01

    Sallie Mae's study, "How America Saves for College 2009," conducted by Gallup, provides a measure of the commitment parents have to helping their children reach higher education and whether and how they are saving for the investment. Based on a nationally representative survey of parents of children under age 18, the study found that without…

  19. Enhancement of pump absorption efficiency by bending and twisting of double clad rare earth doped fibers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Koška, Pavel; Peterka, Pavel; Doya, Valérie; Aubrecht, Jan; Kasik, Ivan; Podrazký, Ondřej

    2017-05-01

    High-power operation of fiber lasers was enabled by the invention of cladding-pumping in a double-clad fiber structure. Because of existence of so called skew rays in the inner clad of the fiber, pump absorption saturates along the fiber and pumping becomes inefficient. First studies of pump absorption efficiency enhancement were focused on fibers with broken circular symmetry of inner cladding eliminating skew rays [1,2]. Later, techniques of unconventional fiber coiling were proposed [3]. However, theoretical studies were limited to the assumption of a straight fiber. Even recently, the rigorous model accounting for fiber bending and twisting was described [4-6]. It was found that bending of the fiber influences modal spectra of the pump radiation and twisting provides quite efficient mode-scrambling. These effects in a synergic manner significantly enhances pump absorption rate in double clad fibers and improves laser system efficiency. In our contribution we review results of numerical modelling of pump absorption in various types of double-clad fibers, e.g., with cross section shape of hexagon, stadium, and circle; two-fiber bundle (so-called GTWave fiber structure) a panda fibers are also analyzed. We investigate pump field modal spectra evolution in hexagonally shaped fiber in straight, bended, and simultaneously bended and twisted fiber which brings new quality to understanding of the mode-scrambling and pump absorption enhancement. Finally, we evaluate the impact of enhanced pump absorption on signal gain in the fiber. These results can have practical impact in construction of fiber lasers: with pump absorption efficiency optimized by our new model (the other models did not take into account fiber twist), the double-clad fiber of shorter length can be used in the fiber lasers and amplifiers. In such a way the harmful influence of background losses and nonlinear effects can be minimized. [1] Doya, V., Legrand, O., Mortessagne, F., "Optimized absorption in a

  20. How America Pays for College, 2011. Sallie Mae's National Study of College Students and Parents

    ERIC Educational Resources Information Center

    Sallie Mae, Inc., 2011

    2011-01-01

    Sallie Mae's national study, "How America Pays for College," now in its fourth year, shows the resilience of American families' strongly held belief in the value of a college education. Even in the face of rising tuition costs and the worst economic decline in a generation, between academic years 2007-2008 and 2009-2010 Americans paid increasingly…

  1. In vitro antibacterial activity of a novel resin-based pulp capping material containing the quaternary ammonium salt MAE-DB and Portland cement.

    PubMed

    Yang, Yanwei; Huang, Li; Dong, Yan; Zhang, Hongchen; Zhou, Wei; Ban, Jinghao; Wei, Jingjing; Liu, Yan; Gao, Jing; Chen, Jihua

    2014-01-01

    Vital pulp preservation in the treatment of deep caries is challenging due to bacterial infection. The objectives of this study were to synthesize a novel, light-cured composite material containing bioactive calcium-silicate (Portland cement, PC) and the antimicrobial quaternary ammonium salt monomer 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB) and to evaluate its effects on Streptococcus mutans growth in vitro. The experimental material was prepared from a 2 : 1 ratio of PC mixed with a resin of 2-hydroxyethylmethacrylate, bisphenol glycerolate dimethacrylate, and triethylene glycol dimethacrylate (4 : 3 : 1) containing 5 wt% MAE-DB. Cured resin containing 5% MAE-DB without PC served as the positive control material, and resin without MAE-DB or PC served as the negative control material. Mineral trioxide aggregate (MTA) and calcium hydroxide (Dycal) served as commercial controls. S. mutans biofilm formation on material surfaces and growth in the culture medium were tested according to colony-forming units (CFUs) and metabolic activity after 24 h incubation over freshly prepared samples or samples aged in water for 6 months. Biofilm formation was also assessed by Live/Dead staining and scanning electron microscopy. S. mutans biofilm formation on the experimental material was significantly inhibited, with CFU counts, metabolic activity, viability staining, and morphology similar to those of biofilms on the positive control material. None of the materials affected bacterial growth in solution. Contact-inhibition of biofilm formation was retained by the aged experimental material. Significant biofilm formation was observed on MTA and Dycal. The synthesized material containing HEMA-BisGMA-TEGDMA resin with MAE-DB as the antimicrobial agent and PC to support mineralized tissue formation inhibited S. mutans biofilm formation even after aging in water for 6 months, but had no inhibitory effect on bacteria in solution. Therefore, this material shows

  2. Efficient energy absorption of intense ps-laser pulse into nanowire target

    NASA Astrophysics Data System (ADS)

    Habara, H.; Honda, S.; Katayama, M.; Sakagami, H.; Nagai, K.; Tanaka, K. A.

    2016-06-01

    The interaction between ultra-intense laser light and vertically aligned carbon nanotubes is investigated to demonstrate efficient laser-energy absorption in the ps laser-pulse regime. Results indicate a clear enhancement of the energy conversion from laser to energetic electrons and a simultaneously small plasma expansion on the surface of the target. A two-dimensional plasma particle calculation exhibits a high absorption through laser propagation deep into the nanotube array, even for a dense array whose structure is much smaller than the laser wavelength. The propagation leads to the radial expansion of plasma perpendicular to the nanotubes rather than to the front side. These features may contribute to fast ignition in inertial confinement fusion and laser particle acceleration, both of which require high current and small surface plasma simultaneously.

  3. Efficient energy absorption of intense ps-laser pulse into nanowire target

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

    Habara, H.; Honda, S.; Katayama, M.

    The interaction between ultra-intense laser light and vertically aligned carbon nanotubes is investigated to demonstrate efficient laser-energy absorption in the ps laser-pulse regime. Results indicate a clear enhancement of the energy conversion from laser to energetic electrons and a simultaneously small plasma expansion on the surface of the target. A two-dimensional plasma particle calculation exhibits a high absorption through laser propagation deep into the nanotube array, even for a dense array whose structure is much smaller than the laser wavelength. The propagation leads to the radial expansion of plasma perpendicular to the nanotubes rather than to the front side. Thesemore » features may contribute to fast ignition in inertial confinement fusion and laser particle acceleration, both of which require high current and small surface plasma simultaneously.« less

  4. Rapid Optimization of External Quantum Efficiency of Thin Film Solar Cells Using Surrogate Modeling of Absorptivity.

    PubMed

    Kaya, Mine; Hajimirza, Shima

    2018-05-25

    This paper uses surrogate modeling for very fast design of thin film solar cells with improved solar-to-electricity conversion efficiency. We demonstrate that the wavelength-specific optical absorptivity of a thin film multi-layered amorphous-silicon-based solar cell can be modeled accurately with Neural Networks and can be efficiently approximated as a function of cell geometry and wavelength. Consequently, the external quantum efficiency can be computed by averaging surrogate absorption and carrier recombination contributions over the entire irradiance spectrum in an efficient way. Using this framework, we optimize a multi-layer structure consisting of ITO front coating, metallic back-reflector and oxide layers for achieving maximum efficiency. Our required computation time for an entire model fitting and optimization is 5 to 20 times less than the best previous optimization results based on direct Finite Difference Time Domain (FDTD) simulations, therefore proving the value of surrogate modeling. The resulting optimization solution suggests at least 50% improvement in the external quantum efficiency compared to bare silicon, and 25% improvement compared to a random design.

  5. Assessment of heavy metals in sediments of the Don Hoi Lot area in the Mae Klong estuary, Thailand.

    PubMed

    Pengthamkeerati, Patthra; Kornkanitnan, Narumol; Sawangarreruks, Suchat; Wanichacheva, Nantanit; Wainiphithapong, Chantana; Sananwai, Nipawan

    2013-01-01

    The status and seasonal variation of heavy metals in surface sediment were investigated at Don Hoi Lot, located in the Mae Klong estuary, Thailand. Results revealed that all the measured heavy metals, except Zn, in the sediments had lower concentrations than in other nearby estuaries. Only Zn may be of concern for potential negative effects on estuarine biota in the study area. With the exception of Fe, all the studied heavy metals showed seasonal variation, but the patterns were diverse. Organic matter and the clay fraction in sediments were good sinks for heavy metals, excluding Zn, while Fe and Mn were good catchers. Principal component analysis suggested that Zn might have different origins and/or mechanisms of transport, accumulation and circulation, compared with the other heavy metals studied. A better understanding of sources and the behavior of Zn would enhance the efficiency of the estuary management plan in this study area.

  6. Analysis of dextromethorphan and dextrorphan in decomposed skeletal tissues by microwave assisted extraction, microplate solid-phase extraction and gas chromatography- mass spectrometry (MAE-MPSPE-GCMS).

    PubMed

    Fraser, Candice D; Cornthwaite, Heather M; Watterson, James H

    2015-08-01

    Analysis of decomposed skeletal tissues for dextromethorphan (DXM) and dextrorphan (DXT) using microwave assisted extraction (MAE), microplate solid-phase extraction (MPSPE) and gas chromatography-mass spectrometry (GC-MS) is described. Rats (n = 3) received 100 mg/kg DXM (i.p.) and were euthanized by CO2 asphyxiation roughly 20 min post-dose. Remains decomposed to skeleton outdoors and vertebral bones were recovered, cleaned, and pulverized. Pulverized bone underwent MAE using methanol as an extraction solvent in a closed microwave system, followed by MPSPE and GC-MS. Analyte stability under MAE conditions was assessed and found to be stable for at least 60 min irradiation time. The majority (>90%) of each analyte was recovered after 15 min. The MPSPE-GCMS method was fit to a quadratic response (R(2)  > 0.99), over the concentration range 10-10 000 ng⋅mL(-1) , with coefficients of variation <20% in triplicate analysis. The MPSPE-GCMS method displayed a limit of detection of 10 ng⋅mL(-1) for both analytes. Following MAE for 60 min (80 °C, 1200 W), MPSPE-GCMS analysis of vertebral bone of DXM-exposed rats detected both analytes in all samples (DXM: 0.9-1.5 µg⋅g(-1) ; DXT: 0.5-1.8 µg⋅g(-1) ). Copyright © 2014 John Wiley & Sons, Ltd.

  7. High-efficient light absorption of monolayer graphene via cylindrical dielectric arrays and the sensing application

    NASA Astrophysics Data System (ADS)

    Zhou, Peng; Zheng, Gaige

    2018-04-01

    The efficiency of graphene-based optoelectronic devices is typically limited by the poor absolute absorption of light. A hybrid structure of monolayer graphene with cylindrical titanium dioxide (TiO2) array and aluminum oxide (Al2O3) spacer layer on aluminum (Al) substrate has been proposed to enhance the absorption for two-dimensional (2D) materials. By combining dielectric array with metal substrate, the structure achieves multiple absorption peaks with near unity absorbance at near-infrared wavelengths due to the resonant effect of dielectric array. Completed monolayer graphene is utilized in the design without any demand of manufacture process to form the periodic patterns. Further analysis indicates that the near-field enhancement induced by surface modes gives rise to the high absorption. This favorable field enhancement and tunability of absorption not only open up new approaches to accelerate the light-graphene interaction, but also show great potential for practical applications in high-performance optoelectronic devices, such as modulators and sensors.

  8. How America Saves for College, 2014: Sallie Mae's National Study of Parents with Children under Age 18

    ERIC Educational Resources Information Center

    Sallie Mae, Inc., 2014

    2014-01-01

    This is the fourth report in the Sallie Mae series "How America Saves for College," which launched in 2009. To understand how American families are planning for their children's education, the study captures data on parents' decision-making about savings, the use of savings vehicles, and the amount they save, as well as attitudes toward…

  9. How America Saves for College, 2013. Sallie Mae's National Study of Parents with Children under Age 18

    ERIC Educational Resources Information Center

    Sallie Mae, Inc., 2013

    2013-01-01

    Sallie Mae has conducted an ongoing study, "How America Pays for College," annually since 2008. Through that study, the researchers are able to provide a clearer picture of how the typical American undergraduate is paying for college today. This report is the third in the "How America Saves for College" series conducted since 2009. Interviews took…

  10. 75 FR 58421 - Notice of Submission of Proposed Information Collection to OMB Ginnie Mae Mortgage-Backed...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-24

    ...The proposed information collection requirement described below has been submitted to the Office of Management and Budget (OMB) for review, as required by the Paperwork Reduction Act. The Department is soliciting public comments on the subject proposal. This information is collected by Ginnie Mae from issuers/customers that participate in its Mortgage-Backed Securities programs to monitor performance and compliance with established rules and regulations.

  11. Chemical and Optical Properties of Water-Soluble Organic Aerosols from Biomass Burning Emissions

    NASA Astrophysics Data System (ADS)

    Yu, J. M.; Park, S.; Cho, S. Y.

    2016-12-01

    Light absorption property by organic aerosols is an important parameter to determine their radiative forcing on global and regional scales. However, the optical measurements by light absorbing aerosols from biomass burning emissions are rather lacking. This study explored the chemical and light-absorption properties of humic-like substances (HULIS) from biomass burning aerosols of three types; rice straw (RS), pine needles (PN), and sesame stem (SS). Water-soluble organic carbon (WSOC) contributed 42.5, 42.0, and 57.0% to the OC concentrations of the RS, PN, and SS emissions, respectively. Respective HULIS (=1.94´HULIS-C) concentrations accounted for 29.5±2.0, 15.3±3.1, and 25.8±4.0% of PM2.5, and contributed 63±5, 36±10, and 51±8% to WSOC concentration. Absorption Ångström exponents (AAEs) of the WSOC fitted between 300 and 400 nm wavelengths were 7.4-8.3, indicating no significant differences among the biomass types. These AAEs are similar to those reported for aqueous extracts of biomass burning HULIS and fresh secondary organic aerosols from ozonolysis of terpenes. HULIS, which is a hydrophobic part of WSOC and a significant fraction of brown carbon, showed absorption spectra similar to brown carbon. WSOC mass absorption efficiency (MAE365) at 365 nm were 1.37, 0.86, and 1.38 m2/g×C for RS, PN, and SS burning aerosols, respectively. The MAE values by WSOC were less than 10% of MAE caused by light-absorbing black carbon. The light absorption of the water extracts at 365 nm indicated that light absorption was more strongly associated with HULIS from biomass burning emissions than with the hydrophilic WSOC fraction.

  12. Absorption of acoustic waves by sunspots. II - Resonance absorption in axisymmetric fibril models

    NASA Technical Reports Server (NTRS)

    Rosenthal, C. S.

    1992-01-01

    Analytical calculations of acoustic waves scattered by sunspots which concentrate on the absorption at the magnetohydrodynamic Alfven resonance are extended to the case of a flux-tube embedded in a uniform atmosphere. The model is based on a flux-tubes of varying radius that are highly structured, translationally invariant, and axisymmetric. The absorbed fractional energy is determined for different flux-densities and subphotospheric locations with attention given to the effects of twist. When the flux is highly concentrated into annuli efficient absorption is possible even when the mean magnetic flux density is low. The model demonstrates low absorption at low azimuthal orders even in the presence of twist which generally increases the range of wave numbers over which efficient absorption can occur. Resonance absorption is concluded to be an efficient mechanism in monolithic sunspots, fibril sunspots, and plage fields.

  13. Determination of efficiency of an aged HPGe detector for gaseous sources by self absorption correction and point source methods

    NASA Astrophysics Data System (ADS)

    Sarangapani, R.; Jose, M. T.; Srinivasan, T. K.; Venkatraman, B.

    2017-07-01

    Methods for the determination of efficiency of an aged high purity germanium (HPGe) detector for gaseous sources have been presented in the paper. X-ray radiography of the detector has been performed to get detector dimensions for computational purposes. The dead layer thickness of HPGe detector has been ascertained from experiments and Monte Carlo computations. Experimental work with standard point and liquid sources in several cylindrical geometries has been undertaken for obtaining energy dependant efficiency. Monte Carlo simulations have been performed for computing efficiencies for point, liquid and gaseous sources. Self absorption correction factors have been obtained using mathematical equations for volume sources and MCNP simulations. Self-absorption correction and point source methods have been used to estimate the efficiency for gaseous sources. The efficiencies determined from the present work have been used to estimate activity of cover gas sample of a fast reactor.

  14. Observation of infrared absorption of InAs quantum dot structures in AlGaAs matrix toward high-efficiency solar cells

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Hirofumi; Watanabe, Katsuyuki; Kotani, Teruhisa; Izumi, Makoto; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2018-06-01

    In accordance with the detailed balance limit model of single-intermediate-band solar cells (IBSCs), the optimum matrix bandgap and IB–conduction band (CB) energy gap are ∼1.9 and 0.7 eV, respectively. We present the room-temperature polarized infrared absorption of 20 stacked InAs quantum dot (QD) structures in the Al0.32Ga0.68As matrix with a bandgap of ∼1.9 eV for the design of high-efficiency IBSCs by using a multipass waveguide geometry. We find that the IB–CB absorption is almost independent of the light polarization, and estimate the magnitude of the absorption per QD layer to be ∼0.01%. We also find that the IB–CB absorption edge of QD structures with a wide-gap matrix is ∼0.41 eV. These results indicate that both the significant increase in the magnitude of IB–CB absorption and the lower energy of the IB state for the higher IB–CB energy gap are necessary toward the realization of high-efficiency IBSCs.

  15. High-Efficiency Nanowire Solar Cells with Omnidirectionally Enhanced Absorption Due to Self-Aligned Indium-Tin-Oxide Mie Scatterers.

    PubMed

    van Dam, Dick; van Hoof, Niels J J; Cui, Yingchao; van Veldhoven, Peter J; Bakkers, Erik P A M; Gómez Rivas, Jaime; Haverkort, Jos E M

    2016-12-27

    Photovoltaic cells based on arrays of semiconductor nanowires promise efficiencies comparable or even better than their planar counterparts with much less material. One reason for the high efficiencies is their large absorption cross section, but until recently the photocurrent has been limited to less than 70% of the theoretical maximum. Here we enhance the absorption in indium phosphide (InP) nanowire solar cells by employing broadband forward scattering of self-aligned nanoparticles on top of the transparent top contact layer. This results in a nanowire solar cell with a photovoltaic conversion efficiency of 17.8% and a short-circuit current of 29.3 mA/cm 2 under 1 sun illumination, which is the highest reported so far for nanowire solar cells and among the highest reported for III-V solar cells. We also measure the angle-dependent photocurrent, using time-reversed Fourier microscopy, and demonstrate a broadband and omnidirectional absorption enhancement for unpolarized light up to 60° with a wavelength average of 12% due to Mie scattering. These results unambiguously demonstrate the potential of semiconductor nanowires as nanostructures for the next generation of photovoltaic devices.

  16. Inverted Ultrathin Organic Solar Cells with a Quasi-Grating Structure for Efficient Carrier Collection and Dip-less Visible Optical Absorption.

    PubMed

    In, Sungjun; Park, Namkyoo

    2016-02-23

    We propose a metallic-particle-based two-dimensional quasi-grating structure for application to an organic solar cell. With the use of oblate spheroidal nanoparticles in contact with an anode of inverted, ultrathin organic solar cells (OSCs), the quasi-grating structure offers strong hybridization between localized surface plasmons and plasmonic gap modes leading to broadband (300~800 nm) and uniform (average ~90%) optical absorption spectra. Both strong optical enhancement in extreme confinement within the active layer (90 nm) and improved hole collection are thus realized. A coupled optical-electrical multi-physics optimization shows a large (~33%) enhancement in the optical absorption (corresponding to an absorption efficiency of ~47%, AM1.5G weighted, visible) when compared to a control OSC without the quasi-grating structure. That translates into a significant electrical performance gain of ~22% in short circuit current and ~15% in the power conversion efficiency (PCE), leading to an energy conversion efficiency (~6%) which is comparable to that of optically-thick inverted OSCs (3-7%). Detailed analysis on the influences of mode hybridization to optical field distributions, exciton generation rate, charge carrier collection efficiency and electrical conversion efficiency is provided, to offer an integrated understanding on the coupled optical-electrical optimization of ultrathin OSCs.

  17. Research of waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Zhang, Yu; Zhou, Liansheng; E, Zhijun; Wang, Kun; Wang, Ziyue; Li, Guohao; Qu, Bin

    2018-02-01

    The waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water has been analyzed. After the operation of heat pump, the influences on power generation and heat generation of unit were taken into account. In the light of the characteristics of heat pump in different operation stages, the energy efficiency of heat pump was evaluated comprehensively on both sides of benefits belonging to electricity and benefits belonging to heat, which adopted the method of contrast test. Thus, the reference of energy efficiency for same type projects was provided.

  18. Bone mineral density at distal forearm in men over 40 years of age in Mae Chaem district, Chiang Mai Province, Thailand: a pilot study.

    PubMed

    Tungjai, Montree; Kaewjaeng, Siriprapa; Jumpee, Chayanit; Sriburee, Sompong; Hongsriti, Pongsiri; Tapanya, Monruedee; Maghanemi, Utumma; Ratanasthien, Kwanchai; Kothan, Suchart

    2017-09-01

    To study the prevalence of bone mineral density (BMD) and osteoporosis in the distal forearm among Thai men over 40 years of age in Mae Chaem District, Chiang Mai Province, Thailand. The subjects in this study were 194 Thai men, aged between 40 and 87 years who resided in Mae Chaem District, Chiang Mai Province, Thailand. Self-administered questionnaires were used for receiving the demographic characteristics information. BMD was measured by peripheral dual energy X-ray absorptiometry at the nondominant distal forearm in all men. The BMD was highest in the age-group 40-49 years and lowest in the age-group 70-87 years. The average T-score at the distal forearm was also highest in the age-group 40-49 years and lowest in the age-group 70-87 years. The BMD decreased as a function of age-group (p < .05). In contrast, the BMD increased as a function of weight (p < .05). Height had weak impact on the BMD in the distal forearm (p > .05). The percentage of osteopenia and osteoporosis are increased as a function of age-group in, while decreased in that of normal bone density. We found the prevalence of osteoporosis in men who resided in Mae Chaem District, Chiang Mai Province, Thailand.

  19. How America Pays for College, 2017. Sallie Mae's 10th National Study of College Students and Parents

    ERIC Educational Resources Information Center

    Sallie Mae Bank, 2017

    2017-01-01

    "How America Pays for College", introduced in 2008, is a Sallie Mae national study conducted by Ipsos that annually surveys undergraduate students and parents of undergraduates about how much they pay for college and the resources they use to fund the expense. Now in its tenth year, this study also asks families about their attitudes…

  20. Variability of absorption heat pump efficiency for domestic water heating and space heating based on time-weighted bin analysis

    DOE PAGES

    Ally, Moonis Raza; Sharma, Vishaldeep

    2017-11-02

    Natural gas-driven absorption heat pumps are under renewed scrutiny as a viable technology for space conditioning and water heating for residential and commercial applications because of natural gas production trends, pricing, and the speculation that it might be a “bridge fuel” in the global transition towards energy sustainability. Since any level of natural gas combustion contributes to atmospheric carbon dioxide accumulation, the merits of natural gas consuming absorption technology are re-examined in this paper from the point of view of expected efficiency throughout the United States using a time-weighted bin temperature analysis. Such analyses are necessary because equipment standards formore » rated performance is restricted to one set ambient condition, whereas in actual practice, the absorption heat pump (AHP) must perform over a considerably wider range of external conditions, where its efficiency may be vastly different from that at the rated condition. Quantification of variation in efficiency and system performance are imperative to address how to provide the desired utility with the least environmental impact. In this paper, we examine limiting features in absorption heat pumps and relate it to systemic performances in sixteen cities across all eight climate zones in the U.S, each containing fifteen bin temperatures. The results indicate that the true expectation of performance of an AHP is significantly less than what might be optimized for the rated condition. Statistical measures of the variation in water heating COPs show that for most cities, the COP at the rated conditions is outside the 95% Confidence Interval. Moreover, it is concluded that deployment of absorption heat pump water heaters (AHPWH) may be restricted geographically by outdoor temperature constraints.« less

  1. Variability of absorption heat pump efficiency for domestic water heating and space heating based on time-weighted bin analysis

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

    Ally, Moonis Raza; Sharma, Vishaldeep

    Natural gas-driven absorption heat pumps are under renewed scrutiny as a viable technology for space conditioning and water heating for residential and commercial applications because of natural gas production trends, pricing, and the speculation that it might be a “bridge fuel” in the global transition towards energy sustainability. Since any level of natural gas combustion contributes to atmospheric carbon dioxide accumulation, the merits of natural gas consuming absorption technology are re-examined in this paper from the point of view of expected efficiency throughout the United States using a time-weighted bin temperature analysis. Such analyses are necessary because equipment standards formore » rated performance is restricted to one set ambient condition, whereas in actual practice, the absorption heat pump (AHP) must perform over a considerably wider range of external conditions, where its efficiency may be vastly different from that at the rated condition. Quantification of variation in efficiency and system performance are imperative to address how to provide the desired utility with the least environmental impact. In this paper, we examine limiting features in absorption heat pumps and relate it to systemic performances in sixteen cities across all eight climate zones in the U.S, each containing fifteen bin temperatures. The results indicate that the true expectation of performance of an AHP is significantly less than what might be optimized for the rated condition. Statistical measures of the variation in water heating COPs show that for most cities, the COP at the rated conditions is outside the 95% Confidence Interval. Moreover, it is concluded that deployment of absorption heat pump water heaters (AHPWH) may be restricted geographically by outdoor temperature constraints.« less

  2. Seasonal variation and light absorption property of carbonaceous aerosol in a typical glacier region of the southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Niu, Hewen; Kang, Shichang; Wang, Hailong; Zhang, Rudong; Lu, Xixi; Qian, Yun; Paudyal, Rukumesh; Wang, Shijin; Shi, Xiaofei; Yan, Xingguo

    2018-05-01

    Deposition and accumulation of light-absorbing carbonaceous aerosol on glacier surfaces can alter the energy balance of glaciers. In this study, 2 years (December 2014 to December 2016) of continuous observations of carbonaceous aerosols in the glacierized region of the Mt. Yulong and Ganhaizi (GHZ) basin are analyzed. The average elemental carbon (EC) and organic carbon (OC) concentrations were 1.51±0.93 and 2.57±1.32 µg m-3, respectively. Although the annual mean OC / EC ratio was 2.45±1.96, monthly mean EC concentrations during the post-monsoon season were even higher than OC in the high altitudes (approximately 5000 m a. s. l. ) of Mt. Yulong. Strong photochemical reactions and local tourism activities were likely the main factors inducing high OC / EC ratios in the Mt. Yulong region during the monsoon season. The mean mass absorption efficiency (MAE) of EC, measured for the first time in Mt. Yulong, at 632 nm with a thermal-optical carbon analyzer using the filter-based method, was 6.82±0.73 m2 g-1, comparable with the results from other studies. Strong seasonal and spatial variations of EC MAE were largely related to the OC abundance. Source attribution analysis using a global aerosol-climate model, equipped with a black carbon (BC) source tagging technique, suggests that East Asia emissions, including local sources, have the dominant contribution (over 50 %) to annual mean near-surface BC in the Mt. Yulong area. There is also a strong seasonal variation in the regional source apportionment. South Asia has the largest contribution to near-surface BC during the pre-monsoon season, while East Asia dominates the monsoon season and post-monsoon season. Results in this study have great implications for accurately evaluating the influences of carbonaceous matter on glacial melting and water resource supply in glacierization areas.

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

    PubMed

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

    2011-03-15

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

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

    PubMed Central

    2011-01-01

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

  5. Efficient reverse saturable absorption of sol-gel hybrid plasmonic glasses

    NASA Astrophysics Data System (ADS)

    Lundén, H.; Lopes, C.; Lindgren, M.; Liotta, A.; Chateau, D.; Lerouge, F.; Chaput, F.; Désert, A.; Parola, S.

    2017-07-01

    Monolithic silica sol-gel glasses doped with platinum(II) acetylide complexes possessing respectively four or six phenylacetylene units (PE2-CH2OH and PE3-CH2OH) in combination with various concentrations of spherical and bipyramidal gold nanoparticles (AuNPs) known to enhance non-linear optical absorption, were prepared and polished to high optical quality. The non-linear absorption of the glasses was measured and compared to glasses doped solely with AuNPs, a platinum(II) acetylide with shorter delocalized structure, or combinations of both. At 532 nm excitation wavelength the chromophore inhibited the non-linear scattering previously found for glasses only doped with AuNPs. The measured non-linear absorption was attributed to reverse saturable absorption from the chromophore, as previously reported for PE2-CH2OH/AuNP glasses. At 600 nm strong nonlinear absorption was observed for the PE3-CH2OH/AuNPs glasses, also attributed to reverse saturable absorption. But contrary to previous findings for PE2-CH2OH/AuNPs, no distinct enhancement of the non-linear absorption for PE3-CH2OH/AuNPs was observed. A numerical population model for PE3-CH2OH was used to give a qualitative explanation of this difference. A stronger linear absorption in PE3-CH2OH would cause the highly absorbing triplet state to populate quicker during the leading edge of the laser pulse and this would in turn reduce the influence from two-photon absorption enhancement from AuNPs.

  6. Integration of Semiconducting Sulfides for Full-Spectrum Solar Energy Absorption and Efficient Charge Separation.

    PubMed

    Zhuang, Tao-Tao; Liu, Yan; Li, Yi; Zhao, Yuan; Wu, Liang; Jiang, Jun; Yu, Shu-Hong

    2016-05-23

    The full harvest of solar energy by semiconductors requires a material that simultaneously absorbs across the whole solar spectrum and collects photogenerated electrons and holes separately. The stepwise integration of three semiconducting sulfides, namely ZnS, CdS, and Cu2-x S, into a single nanocrystal, led to a unique ternary multi-node sheath ZnS-CdS-Cu2-x S heteronanorod for full-spectrum solar energy absorption. Localized surface plasmon resonance (LSPR) in the nonstoichiometric copper sulfide nanostructures enables effective NIR absorption. More significantly, the construction of pn heterojunctions between Cu2-x S and CdS leads to staggered gaps, as confirmed by first-principles simulations. This band alignment causes effective electron-hole separation in the ternary system and hence enables efficient solar energy conversion. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Gastrointestinal citrate absorption in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Fegan, J.; Khan, R.; Poindexter, J.; Pak, C. Y.

    1992-01-01

    Gastrointestinal absorption of citrate was measured in stone patients with idiopathic hypocitraturia to determine if citrate malabsorption could account for low urinary citrate. Citrate absorption was measured directly from recovery of orally administered potassium citrate (40 mEq.) in the intestinal lavage fluid, using an intestinal washout technique. In 7 stone patients citrate absorption, serum citrate levels, peak citrate concentration in serum and area under the curve were not significantly different from those of 7 normal subjects. Citrate absorption was rapid and efficient in both groups, with 96 to 98% absorbed within 3 hours. The absorption of citrate was less efficient from a tablet preparation of potassium citrate than from a liquid preparation, probably due to a delayed release of citrate from wax matrix. However, citrate absorption from solid potassium citrate was still high at 91%, compared to 98% for a liquid preparation. Thus, hypocitraturia is unlikely to be due to an impaired gastrointestinal absorption of citrate in stone patients without overt bowel disease.

  8. Charge reversible gold nanoparticles for high efficient absorption and desorption of DNA

    NASA Astrophysics Data System (ADS)

    Wang, Can; Zhuang, Jiaqi; Jiang, Shan; Li, Jun; Yang, Wensheng

    2012-10-01

    Mercaptoundecylamine and mercaptoundecanoic acid co-modified Au nanoparticles were prepared by two-step ligand exchange of 6-mercaptohexanoic acid modified gold nanoparticles. Such particles terminated by appropriate ratios of the amine and carboxyl groups ( R N/C) were identified to show reversible charge on their surface, which were switchable by pH of the solution. The isoelectric point (IEP) of the particles is tunable by changing the ratios of the amine and carboxyl groups on the particle surfaces. The particles can absorb DNA effectively at pH lower than the IEP driven by the direct electrostatic interactions between DNA and the particle surface. When pH of the solutions was elevated to be higher than the IEP, the absorbed DNA can be released almost completely due to the electrostatic repulsion between the particle surface and DNA. With appropriate R N/C ratios of 0.8, the absorption and desorption efficiencies of DNA were 97 and 98 %, respectively, corresponding an extraction efficiency of 95 %. Such particles with reversible surface charges allow the high efficient extraction of DNA by simply changing pH instead of by changing salt concentration in the conventional salt bridge method.

  9. Type-II GaSb/GaAs quantum-dot intermediate band with extended optical absorption range for efficient solar cells

    NASA Astrophysics Data System (ADS)

    Boustanji, Hela; Jaziri, Sihem

    2018-02-01

    GaSb/GaAs type-II quantum-dot solar cells (QD SCs) have attracted attention as highly efficient intermediate band SCs due to their infrared absorption. Type-II QDs exhibited a staggered confinement potential, where only holes are strongly confined within the dots. Long wavelength light absorption of the QDSCs is enhanced through the improved carriers number in the IB. The absorption of dots depends on their shape, material quality, and composition. Therefore, the optical properties of the GaSbGaAs QDs before and after thermal treatment are studied. Our intraband studies have shown an extended absorption into the long wavelength region 1.77 μ {m}. The annealed QDs have shown significantly more infrared response of 7.2 μ {m} compared to as-grown sample. The photon absorption and hole extraction depend strongly on the thermal annealing process. In this context, emission of holes from localized states in GaSb QDs has been studied using conductance-voltage ( G- V ) characteristics.

  10. Chromium nanoparticle exhibits higher absorption efficiency than chromium picolinate and chromium chloride in Caco-2 cell monolayers.

    PubMed

    Zha, L-Y; Xu, Z-R; Wang, M-Q; Gu, L-Y

    2008-04-01

    This study was conducted to determine whether chromium nanoparticle (CrNano) exhibited higher absorption efficiency and possessed unique absorption mechanism in comparison to chromium picolinate (CrPic) and chromium chloride (CrCl(3)), as was postulated by previous reports. Twenty-one-day-old Caco-2 cell monolayers grown on semipermeable membranes in Snapwell tissue culture bichambers were incubated with CrNano, CrPic or CrCl(3) to examine their transport and uptake respectively. In the concentration range of 0.2-20 micromol/l, transport of CrNano, CrPic and CrCl(3) across Caco-2 monolayers both in apical-to-basolateral and basolateral-to-apical direction was concentration-, and time-dependent, and temperature independent. The apparent permeability coefficient (P(app)) of CrNano was between 5.89 and 7.92 x 10(-6) cm/s and that of CrPic and CrCl(3) was between 3.52 and 5.31 x 10(-6) cm/s and between 0.97 and 1.37 x 10(-6) cm/s respectively. Uptake of CrNano, CrPic and CrCl(3) by both apical and basolateral membranes was concentration- and time-dependent. Uptake of CrNano by apical membrane was significantly (p < 0.05) decreased when the incubation temperature was reduced from 37 degrees C to 4 degrees C. The transport efficiency of CrNano, CrPic and CrCl(3) after incubation for 120 min at 37 degrees C was 15.83% +/- 0.76%, 9.08% +/- 0.25% and 2.11% +/- 0.53% respectively. The uptake efficiency of CrNano, CrPic and CrCl(3) was 10.08% +/- 0.76%, 4.73% +/- 0.60% and 0.88% +/- 0.08% respectively. It was concluded that the epithelial transport of CrNano, CrPic and CrCl(3) across the Caco-2 cell monolayers was mainly via passive transport pathways. In addition, CrNano exhibited considerably higher absorption efficiency than both CrPic and CrCl(3) in Caco-2 cell monolayers.

  11. Cosensitization of D-A-π-A quinoxaline organic dye: efficiently filling the absorption valley with high photovoltaic efficiency.

    PubMed

    Pei, Kai; Wu, Yongzhen; Li, Hui; Geng, Zhiyuan; Tian, He; Zhu, Wei-Hong

    2015-03-11

    In the efficient cosensitization, the pure organic sensitizers with high molecular extinction coefficients and long wavelength response are highly preferable since the dye loading amount for each dye in cosensitization is decreased with respect to single dye sensitization. A D-A-π-A featured quinoxaline organic sensitizer IQ21 is specifically designed. The high conjugation building block of 4H-cyclopenta[2,1-b:3,4-b']dithiophene (CPDT) is introduced as the π bridge, instead of the traditional thiophene unit, especially in realizing high molecular extinction coefficients (up to 66 600 M(-1) cm(-1)) and extending the light response wavelength. With respect to the reference dye IQ4, the slightly lower efficiency of IQ21 (9.03%) arises from the decrease of VOC, which offsets the gain in JSC. While cosensitized with a smaller D-π-A dye S2, the efficiency in IQ21 is further improved to 10.41% (JSC = 19.8 mA cm(-2), VOC = 731 mV, FF = 0.72). The large improvement in efficiency is attributed to the well-matched molecular structures and loading amounts of both dyes in the cosensitization system. We also demonstrated that coabsorbent dye S2 can distinctly compensate the inherent drawbacks of IQ21, not only enhancing the response intensity of IPCE, making up the absorption defects around low wavelength region of IPCE, but also repressing the charge recombination rate to some extent.

  12. Brown carbon and internal mixing in biomass burning particles

    PubMed Central

    Lack, Daniel A.; Langridge, Justin M.; Bahreini, Roya; Cappa, Christopher D.; Middlebrook, Ann M.; Schwarz, Joshua P.

    2012-01-01

    Biomass burning (BB) contributes large amounts of black carbon (BC) and particulate organic matter (POM) to the atmosphere and contributes significantly to the earth’s radiation balance. BB particles can be a complicated optical system, with scattering and absorption contributions from BC, internal mixtures of BC and POM, and wavelength-dependent absorption of POM. Large amounts of POM can also be externally mixed. We report on the unique ability of multi-wavelength photo-acoustic measurements of dry and thermal-denuded absorption to deconstruct this complicated wavelength-dependent system of absorption and mixing. Optical measurements of BB particles from the Four Mile Canyon fire near Boulder, Colorado, showed that internal mixtures of BC and POM enhanced absorption by up to 70%. The data supports the assumption that the POM was very weakly absorbing at 532 nm. Enhanced absorption at 404 nm was in excess of 200% above BC absorption and varied as POM mass changed, indicative of absorbing POM. Absorption by internal mixing of BC and POM contributed 19( ± 8)% to total 404-nm absorption, while BC alone contributed 54( ± 16)%. Approximately 83% of POM mass was externally mixed, the absorption of which contributed 27( ± 15)% to total particle absorption (at 404 nm). The imaginary refractive index and mass absorption efficiency (MAE) of POM at 404 nm changed throughout the sampling period and were found to be 0.007 ± 0.005 and 0.82 ± 0.43 m2 g-1, respectively. Our analysis shows that the MAE of POM can be biased high by up to 50% if absorption from internal mixing of POM and BC is not included. PMID:22927381

  13. Brown carbon and internal mixing in biomass burning particles.

    PubMed

    Lack, Daniel A; Langridge, Justin M; Bahreini, Roya; Cappa, Christopher D; Middlebrook, Ann M; Schwarz, Joshua P

    2012-09-11

    Biomass burning (BB) contributes large amounts of black carbon (BC) and particulate organic matter (POM) to the atmosphere and contributes significantly to the earth's radiation balance. BB particles can be a complicated optical system, with scattering and absorption contributions from BC, internal mixtures of BC and POM, and wavelength-dependent absorption of POM. Large amounts of POM can also be externally mixed. We report on the unique ability of multi-wavelength photo-acoustic measurements of dry and thermal-denuded absorption to deconstruct this complicated wavelength-dependent system of absorption and mixing. Optical measurements of BB particles from the Four Mile Canyon fire near Boulder, Colorado, showed that internal mixtures of BC and POM enhanced absorption by up to 70%. The data supports the assumption that the POM was very weakly absorbing at 532 nm. Enhanced absorption at 404 nm was in excess of 200% above BC absorption and varied as POM mass changed, indicative of absorbing POM. Absorption by internal mixing of BC and POM contributed 19( ± 8)% to total 404-nm absorption, while BC alone contributed 54( ± 16)%. Approximately 83% of POM mass was externally mixed, the absorption of which contributed 27( ± 15)% to total particle absorption (at 404 nm). The imaginary refractive index and mass absorption efficiency (MAE) of POM at 404 nm changed throughout the sampling period and were found to be 0.007 ± 0.005 and 0.82 ± 0.43 m(2) g(-1), respectively. Our analysis shows that the MAE of POM can be biased high by up to 50% if absorption from internal mixing of POM and BC is not included.

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

    USDA-ARS?s Scientific Manuscript database

    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 ...

  15. Food, feeding and absorption efficiencies of the sand dollar, Mellita quinquiesperforata (Leske)

    NASA Astrophysics Data System (ADS)

    Lane, Jacqueline M.; Lawrence, John M.

    1982-04-01

    The sand dollar, Melitta quinquiesperforata, is a ciliary-mucoid feeder, selective for <62 μm (silt-clay) size fraction of surface sediments. Lipid is the primary component of the organic fraction of silt-clay; levels were highest in May and June (17%) and lowest in December and January (8%). Mellita absorbed primarily lipid from the silt-clay; absorption efficiency of all biochemical components was highest in May and June (67 and 61%) and lowest in December and January (negative values). M. quinquiesperforata fed almost continuously with rate of feeding being higher in small animals and at warmer, summer water temperatures. There was significantly more food in the gut at night than in the day.

  16. Seasonal variation and light absorption property of carbonaceous aerosol in a typical glacier region of the southeastern Tibetan Plateau

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

    Niu, Hewen; Kang, Shichang; Wang, Hailong

    Deposition and accumulation of light-absorbing carbonaceous aerosol on glacier surfaces can alter the energy balance of glaciers. In this study, 2 years (December 2014 to December 2016) of continuous observations of carbonaceous aerosols in the glacierized region of the Mt. Yulong and Ganhaizi (GHZ) basin are analyzed. The average elemental carbon (EC) and organic carbon (OC) concentrations were 1.51±0.93 and 2.57±1.32μg m -3, respectively. Although the annual mean OC/EC ratio was 2.45±1.96, monthly mean EC concentrations during the post-monsoon season were even higher than OC in the high altitudes (approximately 5000 m a.s.l.) of Mt. Yulong. Strong photochemical reactions and local tourism activitiesmore » were likely the main factors inducing high OC/EC ratios in the Mt. Yulong region during the monsoon season. The mean mass absorption efficiency (MAE) of EC, measured for the first time in Mt. Yulong, at 632 nm with a thermal-optical carbon analyzer using the filter-based method, was 6.82±0.73 m 2g -1, comparable with the results from other studies. Strong seasonal and spatial variations of EC MAE were largely related to the OC abundance. Source attribution analysis using a global aerosol–climate model, equipped with a black carbon (BC) source tagging technique, suggests that East Asia emissions, including local sources, have the dominant contribution (over 50%) to annual mean near-surface BC in the Mt. Yulong area. There is also a strong seasonal variation in the regional source apportionment. South Asia has the largest contribution to near-surface BC during the pre-monsoon season, while East Asia dominates the monsoon season and post-monsoon season. Results in this study have great implications for accurately evaluating the influences of carbonaceous matter on glacial melting and water resource supply in glacierization areas.« less

  17. Seasonal variation and light absorption property of carbonaceous aerosol in a typical glacieri region of the southeastern Tibetan Plateau

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

    Niu, Hewen; Kang, Shichang; Wang, Hailong

    2018-05-07

    Deposition and accumulation of light-absorbing carbonaceous aerosol on glacier surfaces can alter the energy balance of glaciers. In this study, 2 years (December 2014 to December 2016) of continuous observations of carbonaceous aerosols in the glacierized region of the Mt. Yulong and Ganhaizi (GHZ) basin are analyzed. The average elemental carbon (EC) and organic carbon (OC) concentrations were 1.51±0.93 and 2.57±1.32 µg m−3, respectively. Although the annual mean OC ∕ EC ratio was 2.45±1.96, monthly mean EC concentrations during the post-monsoon season were even higher than OC in the high altitudes (approximately 5000 m a. s. l. ) of Mt. Yulong. Strong photochemical reactions and local tourism activities weremore » likely the main factors inducing high OC ∕ EC ratios in the Mt. Yulong region during the monsoon season. The mean mass absorption efficiency (MAE) of EC, measured for the first time in Mt. Yulong, at 632 nm with a thermal-optical carbon analyzer using the filter-based method, was 6.82±0.73 m2 g−1, comparable with the results from other studies. Strong seasonal and spatial variations of EC MAE were largely related to the OC abundance. Source attribution analysis using a global aerosol–climate model, equipped with a black carbon (BC) source tagging technique, suggests that East Asia emissions, including local sources, have the dominant contribution (over 50 %) to annual mean near-surface BC in the Mt. Yulong area. There is also a strong seasonal variation in the regional source apportionment. South Asia has the largest contribution to near-surface BC during the pre-monsoon season, while East Asia dominates the monsoon season and post-monsoon season. Results in this study have great implications for accurately evaluating the influences of carbonaceous matter on glacial melting and water resource supply in glacierization areas.« less

  18. Absorption of solar radiation by alkali vapors. [for efficient high temperature energy converters

    NASA Technical Reports Server (NTRS)

    Mattick, A. T.

    1978-01-01

    A theoretical study of the direct absorption of solar radiation by the working fluid of high temperature, high efficiency energy converters has been carried out. Alkali vapors and potassium vapor in particular were found to be very effective solar absorbers and suitable thermodynamically for practical high temperature cycles. Energy loss via reradiation from a solar boiler was shown to reduce the overall efficiency of radiation-heated energy converters, although a simple model of radiation transfer in a potassium vapor solar boiler revealed that self-trapping of the reradiation may reduce this loss considerably. A study was also made of the requirements for a radiation boiler window. It was found that for sapphire, one of the best solar transmitting materials, the severe environment in conjunction with high radiation densities will require some form of window protection. An aerodynamic shield is particularly advantageous in this capacity, separating the window from the absorbing vapor to prevent condensation and window corrosion and to reduce the radiation density at the window.

  19. Efficiency of the intermolecular interaction of salicylic acid neutral form and monoanion with Cd2 + ion studied by methods of absorption and fluorescence

    NASA Astrophysics Data System (ADS)

    Lavrik, N. L.; Mulloev, N. U.

    2018-02-01

    The methods of absorption and fluorescence were used to study the efficiency of the interaction between salicylic acid derivatives SAD (neutral SA form and SA monoanion) and Cd2 + ions (in CdBr2 salt) within the range pH = 1.5 ÷ 8. The efficiency was determined from the change in both the absorption band contour and the fluorescence intensity of various SAD forms. It has been established that depending on the SAD form, the addition of CdBr2 to a starting solution leads to the formation of additional absorption for both the shorter wave lengths in the absorption spectrum of the neutral form (at pH < 3) and the longer wave lengths in the absorption spectrum for the HSal- monoanion (at pH > 4). In the fluorescence spectra, the intensity was observed to increase for the neutral SAD form (at pH < 3) and to decrease for the HSal- monoanion (at pH > 4) after addition of CdBr2. The spectral changes were interpreted in the framework of common notions about the effect of three physicochemical factors that determine the interaction between the SAD and the Cd2 + ion and affect the parameters of absorption and fluorescence spectra. These factors are: (1) the decrease in pH after addition of CdBr2 to the SAD solution, (2) the decrease in the efficiency of the H-bonding of SAD molecules to the water ones, and (3) the existence of electrostatic ion-ion interaction between the HSal- monoanion and the Cd2 + ion. The bimolecular fluorescence quenching constants Kq of HSal- monoanion fluorescence quenching by the Cd2 + ion appeared to be substantially less than those of the quenching which would follow either the dynamic (diffusion) or the concentration (static) mechanisms.

  20. Enzymatic digestive activity and absorption efficiency in Tagelus dombeii upon Alexandrium catenella exposure

    NASA Astrophysics Data System (ADS)

    Fernández-Reiriz, M. J.; Navarro, J. M.; Cisternas, B. A.; Babarro, J. M. F.; Labarta, U.

    2013-12-01

    We analyzed absorption efficiency (AE) and digestive enzyme activity (amylase, cellulase complex, and laminarinase) of the infaunal bivalve Tagelus dombeii originating from two geographic sites, Corral-Valdivia and Melinka-Aysén, which have different long-term paralytic shellfish poisoning (PSP) exposure rates. We report the effects of past feeding history (origin) on T. dombeii exposed to a mixed diet containing the toxic dinoflagellate Alexandrium catenella and another dinoflagellate-free control diet over a 12-day period in the laboratory. Absorption efficiency values of T. dombeii individuals that experienced PSP exposure in their habitat (Melinka-Aysén) remained unchanged during exposure to toxic food in the laboratory. In contrast, T. dombeii from a non-PSP exposure field site (Corral-Valdivia) showed a significant reduction in AE with toxic exposure time. This study established that the amylase and cellulase complexes were the most important enzymes in the digestive glands of Tagelus from both sites. The temporal evolution of enzymatic activity under toxic diet was fitted to exponential (amylase and cellulase) and to a logarithmic (laminarinase) models. In all fits, we found significant effect of origin in the model parameters. At the beginning of the experiment, higher enzymatic activity was observed for clams from Corral-Valdivia. The amylase activity decreased with time exposure for individuals from Corral and increased for individuals from Melinka. Cellulase activity did not vary over time for clams from Corral, but increased for individuals from Melinka and laminarinase activity decreased over time for individuals from Corral and remained unchanged over time for Melinka. A feeding history of exposure to the dinoflagellate A. catenella was reflected in the digestive responses of both T. dombeii populations.

  1. An efficient microwave-assisted extraction process of stevioside and rebaudioside-A from Stevia rebaudiana (Bertoni).

    PubMed

    Jaitak, Vikas; Bikram Singh, Bandna; Kaul, V K

    2009-01-01

    Stevioside and rebaudioside-A are major low-calorie diterpene steviol glycosides in the leaves of Stevia rebaudiana. They are widely used as natural sweeteners for diabetic patients, but the long extraction procedures required and the optimisation of product yield present challenging problems. To develop a rapid and effective methodology for the extraction of stevioside and rebaudioside-A from S. rebaudiana leaves and to compare yields using different extraction techniques. Dried and powdered leaves of S. rebaudiana were extracted by conventional, ultrasound and microwave-assisted extraction techniques using methanol, ethanol and water as single solvents as well as in binary mixtures. Conventional cold extraction was performed at 25 degrees C for 12 h while ultrasound extraction was carried out at temperature of 35 +/- 5 degrees C for 30 min. Microwave-assisted extraction (MAE) was carried out at a power level of 80 W for 1 min at 50 degrees C. MAE yielded 8.64 and 2.34% of stevioside and rebaudioside-A, respectively, while conventional and ultrasound techniques yielded 6.54 and 1.20%, and 4.20 and 1.98% of stevioside and rebaudioside-A, respectively. A rapid and efficient method has been developed for the extraction of stevioside and rebaudioside-A in optimum yields using MAE procedure. This method has the advantage of rapid extraction and fast screening of a large number of S. rebaudiana samples for assessment of planting material. MAE saves considerable time, energy and has implications in the quality assessment of stevioside and rebaudioside-A prior to their industrial production from the leaves of S. rebaudiana. Copyright (c) 2009 John Wiley & Sons, Ltd.

  2. Multi-hump potentials for efficient wave absorption in the numerical solution of the time-dependent Schrödinger equation

    NASA Astrophysics Data System (ADS)

    Silaev, A. A.; Romanov, A. A.; Vvedenskii, N. V.

    2018-03-01

    In the numerical solution of the time-dependent Schrödinger equation by grid methods, an important problem is the reflection and wrap-around of the wave packets at the grid boundaries. Non-optimal absorption of the wave function leads to possible large artifacts in the results of numerical simulations. We propose a new method for the construction of the complex absorbing potentials for wave suppression at the grid boundaries. The method is based on the use of the multi-hump imaginary potential which contains a sequence of smooth and symmetric humps whose widths and amplitudes are optimized for wave absorption in different spectral intervals. We show that this can ensure a high efficiency of absorption in a wide range of de Broglie wavelengths, which includes wavelengths comparable to the width of the absorbing layer. Therefore, this method can be used for high-precision simulations of various phenomena where strong spreading of the wave function takes place, including the phenomena accompanying the interaction of strong fields with atoms and molecules. The efficiency of the proposed method is demonstrated in the calculation of the spectrum of high-order harmonics generated during the interaction of hydrogen atoms with an intense infrared laser pulse.

  3. Implanted Silicon Resistor Layers for Efficient Terahertz Absorption

    NASA Technical Reports Server (NTRS)

    Chervenak, J. A.; Abrahams, J.; Allen, C. A.; Benford, D. J.; Henry, R.; Stevenson, T.; Wollack, E.; Moseley, S. H.

    2005-01-01

    Broadband absorption structures are an essential component of large format bolometer arrays for imaging GHz and THz radiation. We have measured electrical and optical properties of implanted silicon resistor layers designed to be suitable for these absorbers. Implanted resistors offer a low-film-stress, buried absorber that is robust to longterm aging, temperature, and subsequent metals processing. Such an absorber layer is readily integrated with superconducting integrated circuits and standard micromachining as demonstrated by the SCUBA II array built by ROE/NIST (1). We present a complete characterization of these layers, demonstrating frequency regimes in which different recipes will be suitable for absorbers. Single layer thin film coatings have been demonstrated as effective absorbers at certain wavelengths including semimetal (2,3), thin metal (4), and patterned metal films (5,6). Astronomical instrument examples include the SHARC II instrument is imaging the submillimeter band using passivated Bi semimetal films and the HAWC instrument for SOFIA, which employs ultrathin metal films to span 1-3 THz. Patterned metal films on spiderweb bolometers have also been proposed for broadband detection. In each case, the absorber structure matches the impedance of free space for optimal absorption in the detector configuration (typically 157 Ohms per square for high absorption with a single or 377 Ohms per square in a resonant cavity or quarter wave backshort). Resonant structures with -20% bandwidth coupled to bolometers are also under development; stacks of such structures may take advantage of instruments imaging over a wide band. Each technique may enable effective absorbers in imagers. However, thin films tend to age, degrade or change during further processing, can be difficult to reproduce, and often exhibit an intrinsic granularity that creates complicated frequency dependence at THz frequencies. Thick metal films are more robust but the requirement for

  4. Efficient absorption of SO2 with low-partial pressures by environmentally benign functional deep eutectic solvents.

    PubMed

    Zhang, Kai; Ren, Shuhang; Hou, Yucui; Wu, Weize

    2017-02-15

    Sulfur dioxide (SO 2 ) emitted from the burning of fossil fuels is one of the main air contaminants. In this work, we found that environmentally benign solvents, deep eutectic solvents (DESs) could be designed with a function to absorb low-partial pressure SO 2 from simulated flue gas. Two kinds of biodegradable functional DESs based on betaine (Bet) and l-carnitine (L-car) as hydrogen bond accepters (HBA) and ethylene glycol (EG) as a hydrogen bond donor (HBD) were prepared with mole ratios of HBA to HBD from 1:3 to 1:5, and they were investigated to absorb SO 2 with different partial pressures at various temperatures. The results showed that the two DESs could absorb low-partial pressure SO 2 efficiently. SO 2 absorption capacities of the DESs with HBA/HBD mole ratio of 1:3 were 0.332mol SO 2 /mol HBA for Bet+EG DES and 0.820mol SO 2 /mol HBA for L-car+EG DES at 40°C with a SO 2 partial pressure of 0.02atm. In addition, the regeneration experiments demonstrated that the absorption capacities of DESs did not change after five absorption and desorption cycles. Furthermore, the absorption mechanism of SO 2 by DESs was studied by FT-IR, 1 H NMR and 13 C NMR spectra. It was found that there are strong acid-base interactions between SO 2 and -COO - on HBA. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Absorption heat pump system

    DOEpatents

    Grossman, Gershon; Perez-Blanco, Horacio

    1984-01-01

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  6. Absorption-heat-pump system

    DOEpatents

    Grossman, G.; Perez-Blanco, H.

    1983-06-16

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  7. Effects of kaolin application on light absorption and distribution, radiation use efficiency and photosynthesis of almond and walnut canopies.

    PubMed

    Rosati, Adolfo; Metcalf, Samuel G; Buchner, Richard P; Fulton, Allan E; Lampinen, Bruce D

    2007-02-01

    Kaolin applied as a suspension to plant canopies forms a film on leaves that increases reflection and reduces absorption of light. Photosynthesis of individual leaves is decreased while the photosynthesis of the whole canopy remains unaffected or even increases. This may result from a better distribution of light within the canopy following kaolin application, but this explanation has not been tested. The objective of this work was to study the effects of kaolin application on light distribution and absorption within tree canopies and, ultimately, on canopy photosynthesis and radiation use efficiency. Photosynthetically active radiation (PAR) incident on individual leaves within the canopy of almond (Prunus dulcis) and walnut (Juglans regia) trees was measured before and after kaolin application in order to study PAR distribution within the canopy. The PAR incident on, and reflected and transmitted by, the canopy was measured on the same day for kaolin-sprayed and control trees in order to calculate canopy PAR absorption. These data were then used to model canopy photosynthesis and radiation use efficiency by a simple method proposed in previous work, based on the photosynthetic response to incident PAR of a top-canopy leaf. Kaolin increased incident PAR on surfaces of inner-canopy leaves, although there was an estimated 20 % loss in PAR reaching the photosynthetic apparatus, due to increased reflection. Assuming a 20 % loss of PAR, modelled photosynthesis and photosynthetic radiation use efficiency (PRUE) of kaolin-coated leaves decreased by only 6.3 %. This was due to (1) more beneficial PAR distribution within the kaolin-sprayed canopy, and (2) with decreasing PAR, leaf photosynthesis decreases less than proportionally, due to the curvature of the photosynthesis response-curve to PAR. The relatively small loss in canopy PRUE (per unit of incident PAR), coupled with the increased incident PAR on the leaf surface on inner-canopy leaves, resulted in an estimated

  8. Development of a high-efficiency, gas-fired, absorption heat pump for residental and small-commercial applications

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

    Phillips, B.A.

    1990-09-01

    The purpose of the total project is to develop a gas-fired absorption heat pump for residential and small-commercial applications that will produce at least 1.6 Btu of heating and 0.7 Btu of cooling per Btu of heat content in the gas being burned. The primary technology advances that can be used to attain the new goals are higher efficiency cycles, increased flue efficiency, and better fluids. Flue efficiency technology is well developed, and fan-assisted combustion systems with condensing heat exchangers can limit flue and insulation losses to the 10% range. If this 10% loss assumption is made, the resulting targetmore » cycle COPs are 1.78 in heating mode and 0.78 in cooling mode at the ARI rating conditions. The objective of Phase 1 was to analyze working fluids and absorption-cycle concepts that are capable of performing at the target COPs and are potentially competitive with existing space-conditioning products in cost, operating life, and reliability. Six advanced cycles were evaluated with ammonia/water as the fluid pair. Then additional analysis was performed with other fluid pairs to determine whether cycle ranking would change depending on which fluid was used. It was concluded that the preferred cycle/fluid was the generator-absorber heat exchange (GAX) cycle using ammonia/water as the fluid pair. A cost estimate made by an independent manufacturing engineering firm for a residential heat pump based on the cycle/fluid combination determined that the GAX heat pump could be cost competitive with existing products. 20 refs., 28 figs., 2 tabs.« less

  9. Effect of Hygrothermal Aging on the Mechanical Properties of Fluorinated and Nonfluorinated Clay-Epoxy Nanocomposites

    PubMed Central

    Hamim, Salah U.; Singh, Raman P.

    2014-01-01

    Hydrophilic nature of epoxy polymers can lead to both reversible and irreversible/permanent changes in epoxy upon moisture absorption. The permanent changes leading to the degradation of mechanical properties due to combined effect of moisture and elevated temperature on EPON 862, Nanomer I.28E, and Somasif MAE clay-epoxy nanocomposites are investigated in this study. The extent of permanent degradation on fracture and flexural properties due to the hygrothermal aging is determined by drying the epoxy and their clay-epoxy nanocomposites after moisture absorption. Significant permanent damage is observed for fracture toughness and flexural modulus, while the extent of permanent damage is less significant for flexural strength. It is also observed that permanent degradation in Somasif MAE clay-epoxy nanocomposites is higher compared to Nanomer I.28E clay-epoxy nanocomposites. Fourier transform infrared (FTIR) spectroscopy revealed that both clays retained their original chemical structure after the absorption-desorption cycle without undergoing significant changes. Scanning electron microscopy (SEM) images of the fracture surfaces provide evidence that Somasif MAE clay particles offered very little resistance to crack propagation in case of redried specimens when compared to Nanomer I.28E counterpart. The reason for the observed higher extent of permanent degradation in Somasif MAE clay-epoxy system has been attributed to the weakening of the filler-matrix interface. PMID:27379285

  10. Effect of Hygrothermal Aging on the Mechanical Properties of Fluorinated and Nonfluorinated Clay-Epoxy Nanocomposites.

    PubMed

    Hamim, Salah U; Singh, Raman P

    2014-01-01

    Hydrophilic nature of epoxy polymers can lead to both reversible and irreversible/permanent changes in epoxy upon moisture absorption. The permanent changes leading to the degradation of mechanical properties due to combined effect of moisture and elevated temperature on EPON 862, Nanomer I.28E, and Somasif MAE clay-epoxy nanocomposites are investigated in this study. The extent of permanent degradation on fracture and flexural properties due to the hygrothermal aging is determined by drying the epoxy and their clay-epoxy nanocomposites after moisture absorption. Significant permanent damage is observed for fracture toughness and flexural modulus, while the extent of permanent damage is less significant for flexural strength. It is also observed that permanent degradation in Somasif MAE clay-epoxy nanocomposites is higher compared to Nanomer I.28E clay-epoxy nanocomposites. Fourier transform infrared (FTIR) spectroscopy revealed that both clays retained their original chemical structure after the absorption-desorption cycle without undergoing significant changes. Scanning electron microscopy (SEM) images of the fracture surfaces provide evidence that Somasif MAE clay particles offered very little resistance to crack propagation in case of redried specimens when compared to Nanomer I.28E counterpart. The reason for the observed higher extent of permanent degradation in Somasif MAE clay-epoxy system has been attributed to the weakening of the filler-matrix interface.

  11. ZnO/ZnSxSe1-x core/shell nanowire arrays as photoelectrodes with efficient visible light absorption

    NASA Astrophysics Data System (ADS)

    Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Safdar, Muhammad; Niu, Mutong; Zhang, Jinping; Huang, Ying; He, Jun

    2012-08-01

    ZnO/ZnSxSe1-x core/shell nanowires have been synthesized on n+-type silicon substrate via a two-step chemical vapor deposition method. Transmission electron microscopy reveals that ZnSxSe1-x can be deposited on the entire surface of ZnO nanowire, forming coaxial heterojunction along ZnO nanowire with very smooth shell surface and high shell thickness uniformity. The photoelectrode after deposition of the ternary alloy shell significantly improves visible light absorption efficiency. Electrochemical impedance spectroscopy results explicitly indicate that the introduction of ZnSxSe1-x shell to ZnO nanowires effectively improves the photogenerated charge separation process. Our finding opens up an efficient means for achieving high efficient energy conversion devices.

  12. Optical absorption of carbon-gold core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Zhaolong; Quan, Xiaojun; Zhang, Zhuomin; Cheng, Ping

    2018-01-01

    In order to enhance the solar thermal energy conversion efficiency, we propose to use carbon-gold core-shell nanoparticles dispersed in liquid water. This work demonstrates theoretically that an absorbing carbon (C) core enclosed in a plasmonic gold (Au) nanoshell can enhance the absorption peak while broadening the absorption band; giving rise to a much higher solar absorption than most previously studied core-shell combinations. The exact Mie solution is used to evaluate the absorption efficiency factor of spherical nanoparticles in the wavelength region from 300 nm to 1100 nm as well as the electric field and power dissipation profiles inside the nanoparticles at specified wavelengths (mostly at the localized surface plasmon resonance wavelength). The field enhancement by the localized plasmons at the gold surfaces boosts the absorption of the carbon particle, resulting in a redshift of the absorption peak with increased peak height and bandwidth. In addition to spherical nanoparticles, we use the finite-difference time-domain method to calculate the absorption of cubic core-shell nanoparticles. Even stronger enhancement can be achieved with cubic C-Au core-shell structures due to the localized plasmonic resonances at the sharp edges of the Au shell. The solar absorption efficiency factor can exceed 1.5 in the spherical case and reach 2.3 in the cubic case with a shell thickness of 10 nm. Such broadband absorption enhancement is in great demand for solar thermal applications including steam generation.

  13. Highly efficient SO₂ absorption and its subsequent utilization by weak base/polyethylene glycol binary system.

    PubMed

    Yang, Zhen-Zhen; He, Liang-Nian; Zhao, Ya-Nan; Yu, Bing

    2013-02-05

    A binary system consisting of polyethylene glycol (PEG, proton donor)/PEG-functionalized base with suitable basicity was developed for efficient gas desulfurization (GDS) and can be regarded as an alternative approach to circumvent the energy penalty problem in the GDS process. High capacity for SO(2) capture up to 4.88 mol of SO(2)/mol of base was achieved even under low partial pressure of SO(2). Furthermore, SO(2) desorption runs smoothly under mild conditions (N(2), 25 °C) and no significant drop in SO(2) absorption was observed after five-successive absorption-desorption cycles. On the other hand, the absorbed SO(2) by PEG(150)MeIm/PEG(150), being considered as the activated form of SO(2), can be directly transformed into value-added chemicals under mild conditions, thus eliminating the energy penalty for SO(2) desorption and simultaneously realizing recycle of the absorbents. Thus, this SO(2) capture and utilization (SCU) process offers an alternative way for GDS and potentially enables the SO(2) conversion from flue gas to useful chemicals as a value-added process.

  14. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R [Albuquerque, NM; Reed, Scott T [Albuquerque, NM; Ashley, Carol S [Albuquerque, NM; Martinez, F Edward [Horseheads, NY

    2004-08-31

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  15. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R [Albuquerque, NM; Reed, Scott T [Albuquerque, NM; Ashley, Carol S [Albuquerque, NM; Martinez, F Edward [Horseheads, NY

    2003-10-14

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  16. Enhanced broadband absorption in nanowire arrays with integrated Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Aghaeipour, Mahtab; Pettersson, Håkan

    2018-05-01

    A near-unity unselective absorption spectrum is desirable for high-performance photovoltaics. Nanowire (NW) arrays are promising candidates for efficient solar cells due to nanophotonic absorption resonances in the solar spectrum. The absorption spectra, however, display undesired dips between the resonance peaks. To achieve improved unselective broadband absorption, we propose to enclose distributed Bragg reflectors (DBRs) in the bottom and top parts of indium phosphide (InP) NWs, respectively. We theoretically show that by enclosing only two periods of In0.56Ga0.44As/InP DBRs, an unselective 78% absorption efficiency (72% for NWs without DBRs) is obtained at normal incidence in the spectral range from 300 nm to 920 nm. Under oblique light incidence, the absorption efficiency is enhanced up to about 85% at an incidence angle of 50°. By increasing the number of DBR periods from two to five, the absorption efficiency is further enhanced up to 95% at normal incidence. In this work, we calculated optical spectra for InP NWs, but the results are expected to be valid for other direct band gap III-V semiconductor materials. We believe that our proposed idea of integrating DBRs in NWs offers great potential for high-performance photovoltaic applications.

  17. Effects of Kaolin Application on Light Absorption and Distribution, Radiation Use Efficiency and Photosynthesis of Almond and Walnut Canopies

    PubMed Central

    Rosati, Adolfo; Metcalf, Samuel G.; Buchner, Richard P.; Fulton, Allan E.; Lampinen, Bruce D.

    2007-01-01

    Background and Aims Kaolin applied as a suspension to plant canopies forms a film on leaves that increases reflection and reduces absorption of light. Photosynthesis of individual leaves is decreased while the photosynthesis of the whole canopy remains unaffected or even increases. This may result from a better distribution of light within the canopy following kaolin application, but this explanation has not been tested. The objective of this work was to study the effects of kaolin application on light distribution and absorption within tree canopies and, ultimately, on canopy photosynthesis and radiation use efficiency. Methods Photosynthetically active radiation (PAR) incident on individual leaves within the canopy of almond (Prunus dulcis) and walnut (Juglans regia) trees was measured before and after kaolin application in order to study PAR distribution within the canopy. The PAR incident on, and reflected and transmitted by, the canopy was measured on the same day for kaolin-sprayed and control trees in order to calculate canopy PAR absorption. These data were then used to model canopy photosynthesis and radiation use efficiency by a simple method proposed in previous work, based on the photosynthetic response to incident PAR of a top-canopy leaf. Key Results Kaolin increased incident PAR on surfaces of inner-canopy leaves, although there was an estimated 20 % loss in PAR reaching the photosynthetic apparatus, due to increased reflection. Assuming a 20 % loss of PAR, modelled photosynthesis and photosynthetic radiation use efficiency (PRUE) of kaolin-coated leaves decreased by only 6·3 %. This was due to (1) more beneficial PAR distribution within the kaolin-sprayed canopy, and (2) with decreasing PAR, leaf photosynthesis decreases less than proportionally, due to the curvature of the photosynthesis response-curve to PAR. The relatively small loss in canopy PRUE (per unit of incident PAR), coupled with the increased incident PAR on the leaf surface on

  18. Direct and Quantitative Photothermal Absorption Spectroscopy of Individual Particulates

    DTIC Science & Technology

    2013-01-01

    1(a). By taking the ratio of the spectral absorption efficiency of the microwire to the corresponding volumetri - cally equivalent thin film, an...of D¼ 983 nm. For further comparison, the theoretical spectral absorption efficiency for a volumetri - cally equivalent (t¼ 983p/4 nm) thin film, Qabs

  19. Potential role of acetyl-CoA synthetase (acs) and malate dehydrogenase (mae) in the evolution of the acetate switch in Bacteria and Archaea

    USGS Publications Warehouse

    Barnhart, Elliott P.; McClure, Marcella A.; Johnson, Kiki; Cleveland, Sean; Hunt, Kristopher A.; Fields, Matthew W.

    2015-01-01

    Although many Archaea have AMP-Acs (acetyl-coenzyme A synthetase) and ADP-Acs, the extant methanogenic genus Methanosarcina is the only identified Archaeal genus that can utilize acetate via acetate kinase (Ack) and phosphotransacetylase (Pta). Despite the importance of ack as the potential urkinase in the ASKHA phosphotransferase superfamily, an origin hypothesis does not exist for the acetate kinase in Bacteria, Archaea, or Eukarya. Here we demonstrate that Archaeal AMP-Acs and ADP-Acs contain paralogous ATPase motifs previously identified in Ack, which demonstrate a novel relation between these proteins in Archaea. The identification of ATPase motif conservation and resulting structural features in AMP- and ADP-acetyl-CoA synthetase proteins in this study expand the ASKHA superfamily to include acetyl-CoA synthetase. Additional phylogenetic analysis showed that Pta and MaeB sequences had a common ancestor, and that the Pta lineage within the halophilc archaea was an ancestral lineage. These results suggested that divergence of a duplicated maeB within an ancient halophilic, archaeal lineage formed a putative pta ancestor. These results provide a potential scenario for the establishment of the Ack/Pta pathway and provide novel insight into the evolution of acetate metabolism for all three domains of life.

  20. Potential Role of Acetyl-CoA Synthetase (acs) and Malate Dehydrogenase (mae) in the Evolution of the Acetate Switch in Bacteria and Archaea

    DOE PAGES

    Barnhart, Elliott P.; McClure, Marcella A.; Johnson, Kiki; ...

    2015-08-03

    Although many Archaea have AMP-Acs (acetyl-coenzyme A synthetase) and ADP-Acs, the extant methanogenic genus Methanosarcina is the only identified Archaeal genus that can utilize acetate via acetate kinase (Ack) and phosphotransacetylase (Pta). Despite the importance of ack as the potential urkinase in the ASKHA phosphotransferase superfamily, an origin hypothesis does not exist for the acetate kinase in Bacteria, Archaea, or Eukarya. Here we demonstrate that Archaeal AMP-Acs and ADP-Acs contain paralogous ATPase motifs previously identified in Ack, which demonstrate a novel relation between these proteins in Archaea. The identification of ATPase motif conservation and resulting structural features in AMP- andmore » ADP-acetyl-CoA synthetase proteins in this study expand the ASKHA superfamily to include acetyl-CoA synthetase. Additional phylogenetic analysis showed that Pta and MaeB sequences had a common ancestor, and that the Pta lineage within the halophilc archaea was an ancestral lineage. Lastly, these results suggested that divergence of a duplicated maeB within an ancient halophilic, archaeal lineage formed a putative pta ancestor. These results provide a potential scenario for the establishment of the Ack/Pta pathway and provide novel insight into the evolution of acetate metabolism for all three domains of life.« less

  1. New configurations of a heat recovery absorption heat pump integrated with a natural gas boiler for boiler efficiency improvement

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

    Qu, Ming; Abdelaziz, Omar; Yin, Hongxi

    2014-11-01

    Conventional natural gas-fired boilers exhaust flue gas direct to the atmosphere at 150 200 C, which, at such temperatures, contains large amount of energy and results in relatively low thermal efficiency ranging from 70% to 80%. Although condensing boilers for recovering the heat in the flue gas have been developed over the past 40 years, their present market share is still less than 25%. The major reason for this relatively slow acceptance is the limited improvement in the thermal efficiency of condensing boilers. In the condensing boiler, the temperature of the hot water return at the range of 50 60more » C, which is used to cool the flue gas, is very close to the dew point of the water vapor in the flue gas. Therefore, the latent heat, the majority of the waste heat in the flue gas, which is contained in the water vapor, cannot be recovered. This paper presents a new approach to improve boiler thermal efficiency by integrating absorption heat pumps with natural gas boilers for waste heat recovery (HRAHP). Three configurations of HRAHPs are introduced and discussed. The three configurations are modeled in detail to illustrate the significant thermal efficiency improvement they attain. Further, for conceptual proof and validation, an existing hot water-driven absorption chiller is operated as a heat pump at operating conditions similar to one of the devised configurations. An overall system performance and economic analysis are provided for decision-making and as evidence of the potential benefits. These three configurations of HRAHP provide a pathway to achieving realistic high-efficiency natural gas boilers for applications with process fluid return temperatures higher than or close to the dew point of the water vapor in the flue gas.« less

  2. A B-C-N hybrid porous sheet: an efficient metal-free visible-light absorption material.

    PubMed

    Lu, Ruifeng; Li, Feng; Salafranca, Juan; Kan, Erjun; Xiao, Chuanyun; Deng, Kaiming

    2014-03-07

    The polyphenylene network, known as porous graphene, is one of the most important and widely studied two-dimensional materials. As a potential candidate for photocatalysis and photovoltaic energy generation, its application has been limited by the low photocatalytic activity in the visible-light region. State-of-the-art hybrid density functional theory investigations are presented to show that an analogous B-C-N porous sheet outperforms the pristine polyphenylene network with significantly enhanced visible-light absorption. Compared with porous graphene, the calculated energy gap of the B-C-N hybrid crystal shrinks to 2.7 eV and the optical absorption peak remarkably shifts to the visible light region. The redox potentials of water splitting are well positioned in the middle of the band gap. Hybridizations among B_p, N_p and C_p orbitals are responsible for these findings. Valence and conduction band calculations indicate that the electrons and holes can be effectively separated, reducing charge recombination and improving the photoconversion efficiency. Moreover, the band gap and optical properties of the B-C-N hybrid porous sheet can be further finely engineered by external strain.

  3. Perfect absorption in nanotextured thin films via Anderson-localized photon modes

    NASA Astrophysics Data System (ADS)

    Aeschlimann, Martin; Brixner, Tobias; Differt, Dominik; Heinzmann, Ulrich; Hensen, Matthias; Kramer, Christian; Lükermann, Florian; Melchior, Pascal; Pfeiffer, Walter; Piecuch, Martin; Schneider, Christian; Stiebig, Helmut; Strüber, Christian; Thielen, Philip

    2015-10-01

    The enhancement of light absorption in absorber layers is crucial in a number of applications, including photovoltaics and thermoelectrics. The efficient use of natural resources and physical constraints such as limited charge extraction in photovoltaic devices require thin but efficient absorbers. Among the many different strategies used, light diffraction and light localization at randomly nanotextured interfaces have been proposed to improve absorption. Although already exploited in commercial devices, the enhancement mechanism for devices with nanotextured interfaces is still subject to debate. Using coherent two-dimensional nanoscopy and coherent light scattering, we demonstrate the existence of localized photonic states in nanotextured amorphous silicon layers as used in commercial thin-film solar cells. Resonant absorption in these states accounts for the enhanced absorption in the long-wavelength cutoff region. Our observations establish that Anderson localization—that is, strong localization—is a highly efficient resonant absorption enhancement mechanism offering interesting opportunities for the design of efficient future absorber layers.

  4. Physiological Importance and Mechanisms of Protein Hydrolysate Absorption

    NASA Astrophysics Data System (ADS)

    Zhanghi, Brian M.; Matthews, James C.

    Understanding opportunities to maximize the efficient digestion and assimilation by production animals of plant- and animal-derived protein products is critical for farmers, nutritionists, and feed manufacturers to sustain and expand the affordable production of high quality animal products for human consumption. The challenge to nutritionists is to match gastrointestinal tract load to existing or ­inducible digestive and absorptive capacities. The challenge to feed manufacturers is to develop products that are efficient substrates for digestion, absorption, and/or both events. Ultimately, the efficient absorption of digesta proteins depends on the mediated passage (transport) of protein hydrosylate products as dipeptides and unbound amino acids across the lumen- and blood-facing membranes of intestinal absorptive cells. Data testing the relative efficiency of supplying protein as hydrolysates or specific dipeptides versus as free amino acids, and the response of animals in several physiological states to feeding of protein hydrolysates, are presented and reviewed in this chapter. Next, data describing the transport mechanisms responsible for absorbing protein hydrolysate digestion products, and the known and putative regulation of these mechanisms by their substrates (small peptides) and hormones are presented and reviewed. Several conclusions are drawn regarding the efficient use of protein hydrolysate-based diets for particular physiological states, the economically-practical application of which likely will depend on technological advances in the manufacture of protein hydrolysate products.

  5. Geometrical dependence of spin current absorption into a ferromagnetic nanodot

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

    Nomura, Tatsuya; Ohnishi, Kohei; Kimura, Takashi, E-mail: t-kimu@phys.kyushu-u.ac.jp

    We have investigated the absorption property of the diffusive pure spin current due to a ferromagnetic nanodot in a laterally configured ferromagnetic/nonmagnetic hybrid nanostructure. The spin absorption in a nano-pillar-based lateral-spin-valve structure was confirmed to increase with increasing the lateral dimension of the ferromagnetic dot. However, the absorption efficiency was smaller than that in a conventional lateral spin valve based on nanowire junctions because the large effective cross section of the two dimensional nonmagnetic film reduces the spin absorption selectivity. We also found that the absorption efficiency of the spin current is significantly enhanced by using a thick ferromagnetic nanodot.more » This can be understood by taking into account the spin absorption through the side surface of the ferromagnetic dot quantitatively.« less

  6. Broadband Light Absorption and Efficient Charge Separation Using a Light Scattering Layer with Mixed Cavities for High-Performance Perovskite Photovoltaic Cells with Stability.

    PubMed

    Moon, Byeong Cheul; Park, Jung Hyo; Lee, Dong Ki; Tsvetkov, Nikolai; Ock, Ilwoo; Choi, Kyung Min; Kang, Jeung Ku

    2017-08-01

    CH 3 NH 3 PbI 3 is one of the promising light sensitizers for perovskite photovoltaic cells, but a thick layer is required to enhance light absorption in the long-wavelength regime ranging from PbI 2 absorption edge (500 nm) to its optical band-gap edge (780 nm) in visible light. Meanwhile, the thick perovskite layer suppresses visible-light absorption in the short wavelengths below 500 nm and charge extraction capability of electron-hole pairs produced upon light absorption. Herein, we find that a new light scattering layer with the mixed cavities of sizes in 100 and 200 nm between transparent fluorine-doped tin oxide and mesoporous titanium dioxide electron transport layer enables full absorption of short-wavelength photons (λ < 500 nm) to the perovskite along with enhanced absorption of long-wavelength photons (500 nm < λ < 780 nm). Moreover, the light-driven electric field is proven to allow efficient charge extraction upon light absorption, thereby leading to the increased photocurrent density as well as the fill factor prompted by the slow recombination rate. Additionally, the photocurrent density of the cell with a light scattering layer of mixed cavities is stabilized due to suppressed charge accumulation. Consequently, this work provides a new route to realize broadband light harvesting of visible light for high-performance perovskite photovoltaic cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Measurements of the intrinsic quantum efficiency and absorption length of tetraphenyl butadiene thin films in the vacuum ultraviolet regime

    NASA Astrophysics Data System (ADS)

    Benson, Christopher; Gann, Gabriel Orebi; Gehman, Victor

    2018-04-01

    A key enabling technology for many liquid noble gas (LNG) detectors is the use of the common wavelength shifting medium tetraphenyl butadiene (TPB). TPB thin films are used to shift ultraviolet scintillation light into the visible spectrum for detection and event reconstruction. Understanding the wavelength shifting efficiency and optical properties of these films are critical aspects in detector performance and modeling and hence in the ultimate physics sensitivity of such experiments. This article presents the first measurements of the room-temperature microphysical quantum efficiency for vacuum-deposited TPB thin films - a result that is independent of the optics of the TPB or substrate. Also presented are measurements of the absorption length in the vacuum ultraviolet regime, the secondary re-emission efficiency, and more precise results for the "black-box" efficiency across a broader spectrum of wavelengths than previous results. The low-wavelength sensitivity, in particular, would allow construction of LNG scintillator detectors with lighter elements (Ne, He) to target light mass WIMPs.

  8. Absorption heat pump system

    DOEpatents

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  9. Absorption heat pump system

    DOEpatents

    Grossman, Gershon

    1984-01-01

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  10. Spatio-Temporal Convergence of Maximum Daily Light-Use Efficiency Based on Radiation Absorption by Canopy Chlorophyll

    NASA Astrophysics Data System (ADS)

    Zhang, Yao; Xiao, Xiangming; Wolf, Sebastian; Wu, Jin; Wu, Xiaocui; Gioli, Beniamino; Wohlfahrt, Georg; Cescatti, Alessandro; van der Tol, Christiaan; Zhou, Sha; Gough, Christopher M.; Gentine, Pierre; Zhang, Yongguang; Steinbrecher, Rainer; Ardö, Jonas

    2018-04-01

    Light-use efficiency (LUE), which quantifies the plants' efficiency in utilizing solar radiation for photosynthetic carbon fixation, is an important factor for gross primary production estimation. Here we use satellite-based solar-induced chlorophyll fluorescence as a proxy for photosynthetically active radiation absorbed by chlorophyll (APARchl) and derive an estimation of the fraction of APARchl (fPARchl) from four remotely sensed vegetation indicators. By comparing maximum LUE estimated at different scales from 127 eddy flux sites, we found that the maximum daily LUE based on PAR absorption by canopy chlorophyll (ɛmaxchl), unlike other expressions of LUE, tends to converge across biome types. The photosynthetic seasonality in tropical forests can also be tracked by the change of fPARchl, suggesting the corresponding ɛmaxchl to have less seasonal variation. This spatio-temporal convergence of LUE derived from fPARchl can be used to build simple but robust gross primary production models and to better constrain process-based models.

  11. Energy absorption of composite material and structure

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1987-01-01

    Results are presented from a joint research program on helicopter crashworthiness conducted by the U.S. Army Aerostructures Directorate and NASA Langley. Through the ongoing research program an in-depth understanding has been developed on the cause/effect relationships between material and architectural variables and the energy-absorption capability of composite material and structure. Composite materials were found to be efficient energy absorbers. Graphite/epoxy subfloor structures were more efficient energy absorbers than comparable structures fabricated from Kevlar or aluminum. An accurate method of predicting the energy-absorption capability of beams was developed.

  12. Importance of the green color, absorption gradient, and spectral absorption of chloroplasts for the radiative energy balance of leaves.

    PubMed

    Kume, Atsushi

    2017-05-01

    Terrestrial green plants absorb photosynthetically active radiation (PAR; 400-700 nm) but do not absorb photons evenly across the PAR waveband. The spectral absorbance of photosystems and chloroplasts is lowest for green light, which occurs within the highest irradiance waveband of direct solar radiation. We demonstrate a close relationship between this phenomenon and the safe and efficient utilization of direct solar radiation in simple biophysiological models. The effects of spectral absorptance on the photon and irradiance absorption processes are evaluated using the spectra of direct and diffuse solar radiation. The radiation absorption of a leaf arises as a consequence of the absorption of chloroplasts. The photon absorption of chloroplasts is strongly dependent on the distribution of pigment concentrations and their absorbance spectra. While chloroplast movements in response to light are important mechanisms controlling PAR absorption, they are not effective for green light because chloroplasts have the lowest spectral absorptance in the waveband. With the development of palisade tissue, the incident photons per total palisade cell surface area and the absorbed photons per chloroplast decrease. The spectral absorbance of carotenoids is effective in eliminating shortwave PAR (<520 nm), which contains much of the surplus energy that is not used for photosynthesis and is dissipated as heat. The PAR absorptance of a whole leaf shows no substantial difference based on the spectra of direct or diffuse solar radiation. However, most of the near infrared radiation is unabsorbed and heat stress is greatly reduced. The incident solar radiation is too strong to be utilized for photosynthesis under the current CO 2 concentration in the terrestrial environment. Therefore, the photon absorption of a whole leaf is efficiently regulated by photosynthetic pigments with low spectral absorptance in the highest irradiance waveband and through a combination of pigment density

  13. [Purification of complicated industrial organic waste gas by complex absorption].

    PubMed

    Chen, Ding-Sheng; Cen, Chao-Ping; Tang, Zhi-Xiong; Fang, Ping; Chen, Zhi-Hang

    2011-12-01

    Complicated industrial organic waste gas with the characteristics of low concentration,high wind volume containing inorganic dust and oil was employed the research object by complex absorption. Complex absorption mechanism, process flow, purification equipment and engineering application were studied. Three different surfactants were prepared for the composite absorbent to purify exhaust gas loaded with toluene and butyl acetate, respectively. Results show that the low surface tension of the composite absorbent can improve the removal efficiency of toluene and butyl acetate. With the advantages of the water film, swirl plate and fill absorption device, efficient absorption equipment was developed for the treatment of complicated industrial organic waste gas. It is with superiorities of simple structure, small size, anti-jam and high mass transfer. Based on absorption technology, waste gas treatment process integrated with heating stripping, burning and anaerobic and other processes, so that emissions of waste gas and absorption solution could meet the discharge standards. The technology has been put into practice, such as manufacturing and spraying enterprises.

  14. Adaptation of calcium absorption during treatment of nutritional rickets in Nigerian children

    USDA-ARS?s Scientific Manuscript database

    Nutritional rickets in Nigerian children has been effectively treated with Ca supplementation. High values of Ca absorption efficiency have been observed in untreated children, but whether Ca absorption efficiency changes during treatment with Ca is unknown. Our objective in conducting this study wa...

  15. Optimization of microwave-assisted extraction for the characterization of olive leaf phenolic compounds by using HPLC-ESI-TOF-MS/IT-MS(2).

    PubMed

    Taamalli, Amani; Arráez-Román, David; Ibañez, Elena; Zarrouk, Mokhtar; Segura-Carretero, Antonio; Fernández-Gutiérrez, Alberto

    2012-01-25

    In the present work, a simple and rapid method for the extraction of phenolic compounds from olive leaves, using microwave-assisted extraction (MAE) technique, has been developed. The experimental variables that affect the MAE process, such as the solvent type and composition, microwave temperature, and extraction time, were optimized using a univariate method. The obtained extracts were analyzed by using high-performance liquid chromatography (HPLC) coupled to electrospray time-of-flight mass spectrometry (ESI-TOF-MS) and electrospray ion trap tandem mass spectrometry (ESI-IT-MS(2)) to prove the MAE extraction efficiency. The optimal MAE conditions were methanol:water (80:20, v/v) as extracting solvent, at a temperature equal to 80 °C for 6 min. Under these conditions, several phenolic compounds could be characterized by HPLC-ESI-MS/MS(2). As compared to the conventional method, MAE can be used as an alternative extraction method for the characterization of phenolic compounds from olive leaves due to its efficiency and speed.

  16. CuTaS 3 : Intermetal d–d Transitions Enable High Solar Absorption

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

    Heo, Jaeseok; Yu, Liping; Altschul, Emmeline

    To realize the fundamental limits of photovoltaic device efficiency, solar absorbers must exhibit strong absorption and abrupt absorption onsets. Ideally, onsets to maximum absorption (a > 105 cm-1) occur over a few tenths of an electronvolt. First-principles calculations predict CuTaS3 represents a potentially new class of materials with such absorption characteristics. Narrow metallic d bands in both the initial and final states present high joint densities of states and, therefore, strong absorption. Specifically, a mixture of metal d (Cu1+, d10) and S p characterizes states near the valence band maximum, and metal d (Ta5+, d0) dominates near the conduction bandmore » minimum. Optical absorption measurements on thin films confirm the abrupt onset to strong absorption a > 105 cm-1 at Eg + 0.4 eV (Eg = 1.0 eV). Theoretical CuTaS3 solar cell efficiency is predicted to be 28% for a 300 nm film based on the metric of spectroscopic limited maximum efficiency, which exceeds that of CuInSe2. This sulfide may offer new opportunities to discover and develop a new class of mixed d-element solar absorbers.« less

  17. Infrared absorption cross-sections, radiative efficiency and global warming potential of HFC-43-10mee

    NASA Astrophysics Data System (ADS)

    Le Bris, Karine; DeZeeuw, Jasmine; Godin, Paul J.; Strong, Kimberly

    2018-06-01

    HFC-43-10mee (C5H2F10) is a substitute for CFC-113, HCFC-141b and methyl chloroform, as well as an alternative to perfluorocarbons with high radiative efficiencies. Recent observations have shown that the global mean tropospheric abundance of HFC-43-10mee has increased steadily from the 1990s to reach 0.211 ppt in 2012. To date, the emission of this compound is not regulated. The radiative efficiency (RE) of HFC-43-10mee has recently been re-evaluated at 0.42 W m-2 ppb-1, giving a 100-year time horizon global warming potential (GWP100) of 1650. However, the initial RE, from which the new values were derived, originated from an unpublished source. We calculated a new RE of 0.36 W m-2 ppb-1 and a GWP100 of 1410 from laboratory absorption cross-section spectra of a pure vapour of HFC-43-10mee. Acquisitions were performed in the 550-3500 cm-1 spectral range using Fourier transform spectroscopy. The results were compared with the broadened spectra from the Pacific Northwest National Laboratory (PNNL) database and with theoretical calculations using density functional theory.

  18. Spatio-temporal Convergence of Maximum Daily Light-Use Efficiency Based on Radiation Absorption by Canopy Chlorophyll

    DOE PAGES

    Zhang, Yao; Xiao, Xiangming; Wolf, Sebastian; ...

    2018-04-03

    Light-use efficiency (LUE), which quantifies the plants’ efficiency in utilizing solar radiation for photosynthetic carbon fixation, is an important factor for gross primary production (GPP) estimation. Here we use satellite-based solar-induced chlorophyll fluorescence (SIF) as a proxy for photosynthetically active radiation absorbed by chlorophyll (APAR chl) and derive an estimation of the fraction of APAR chl (fPAR chl) from four remotely-sensed vegetation indicators. By comparing maximum LUE estimated at different scales from 127 eddy flux sites, we found that the maximum daily LUE based on PAR absorption by canopy chlorophyll (εmore » $$chl\\atop{max}$$), unlike other expressions of LUE, tends to converge across biome types. The photosynthetic seasonality in tropical forests can also be tracked by the change of fPAR chl, suggesting the corresponding (ε$$chl\\atop{max}$$}$) to have less seasonal variation. Finally, this spatio-temporal convergence of LUE derived from fPAR chl can be used to build simple but robust GPP models and to better constrain process-based models.« less

  19. Spatio-temporal Convergence of Maximum Daily Light-Use Efficiency Based on Radiation Absorption by Canopy Chlorophyll

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

    Zhang, Yao; Xiao, Xiangming; Wolf, Sebastian

    Light-use efficiency (LUE), which quantifies the plants’ efficiency in utilizing solar radiation for photosynthetic carbon fixation, is an important factor for gross primary production (GPP) estimation. Here we use satellite-based solar-induced chlorophyll fluorescence (SIF) as a proxy for photosynthetically active radiation absorbed by chlorophyll (APAR chl) and derive an estimation of the fraction of APAR chl (fPAR chl) from four remotely-sensed vegetation indicators. By comparing maximum LUE estimated at different scales from 127 eddy flux sites, we found that the maximum daily LUE based on PAR absorption by canopy chlorophyll (εmore » $$chl\\atop{max}$$), unlike other expressions of LUE, tends to converge across biome types. The photosynthetic seasonality in tropical forests can also be tracked by the change of fPAR chl, suggesting the corresponding (ε$$chl\\atop{max}$$}$) to have less seasonal variation. Finally, this spatio-temporal convergence of LUE derived from fPAR chl can be used to build simple but robust GPP models and to better constrain process-based models.« less

  20. Food Ingredients That Inhibit Cholesterol Absorption

    PubMed Central

    Jesch, Elliot D.; Carr, Timothy P.

    2017-01-01

    Cholesterol is a vital component of the human body. It stabilizes cell membranes and is the precursor of bile acids, vitamin D and steroid hormones. However, cholesterol accumulation in the bloodstream (hypercholesterolemia) can cause atherosclerotic plaques within artery walls, leading to heart attacks and strokes. The efficiency of cholesterol absorption in the small intestine is of great interest because human and animal studies have linked cholesterol absorption with plasma concentration of total and low density lipoprotein cholesterol. Cholesterol absorption is highly regulated and influenced by particular compounds in the food supply. Therefore, it is desirable to learn more about natural food components that inhibit cholesterol absorption so that food ingredients and dietary supplements can be developed for consumers who wish to manage their plasma cholesterol levels by non-pharmacological means. Food components thus far identified as inhibitors of cholesterol absorption include phytosterols, soluble fibers, phospholipids, and stearic acid. PMID:28702423

  1. The characteristics of brown carbon aerosol during winter in Beijing

    NASA Astrophysics Data System (ADS)

    Cheng, Yuan; He, Ke-bin; Du, Zhen-yu; Engling, Guenter; Liu, Jiu-meng; Ma, Yong-liang; Zheng, Mei; Weber, Rodney J.

    2016-02-01

    Brown carbon (i.e., light-absorbing organic carbon, or BrC) exerts important effects on the environment and on climate in particular. Based on spectrophotometric absorption measurements on extracts of bulk aerosol samples, this study investigated the characteristics of BrC during winter in Beijing, China. Organic compounds extractable by methanol contributed approximately 85% to the organic carbon (OC) mass. Light absorption by the methanol extracts exhibited a strong wavelength dependence, with an average absorption Ångström exponent of 7.10 (fitted between 310 and 450 nm). Normalizing the absorption coefficient (babs) measured at 365 nm to the extractable OC mass yielded an average mass absorption efficiency (MAE) of 1.45 m2/g for the methanol extracts. This study suggests that light absorption by BrC could be comparable with black carbon in the spectral range of near-ultraviolet light. Our results also indicate that BrC absorption and thus BrC radiative forcing could be largely underestimated when using water-soluble organic carbon (WSOC) as a surrogate for BrC. Compared to previous work relying only on WSOC, this study provides a more comprehensive understanding of BrC aerosol based on methanol extraction.

  2. Absorption machine with desorber-resorber

    DOEpatents

    Biermann, Wendell J.

    1985-01-01

    An absorption refrigeration system utilizing a low temperature desorber and intermediate temperature resorber. The system operates at three temperatures and three pressures to increase the efficiency of the system and is capable of utilizing a lower generator temperature than previously used.

  3. Microwave-assisted extraction of silkworm pupal oil and evaluation of its fatty acid composition, physicochemical properties and antioxidant activities.

    PubMed

    Hu, Bin; Li, Cheng; Zhang, Zhiqing; Zhao, Qing; Zhu, Yadong; Su, Zhao; Chen, Yizi

    2017-09-15

    Microwave-assisted extraction (MAE) of oil from silkworm pupae was firstly performed in the present research. The response surface methodology was applied to optimize the parameters for MAE. The yield of oil by MAE was 30.16% under optimal conditions of a mixed solvent consisting of ethanol and n-hexane (1:1, v/v), microwave power (360W), liquid to solid ratio (7.5/1mL/g), microwave time (29min). Moreover, oil extracted by MAE was quantitatively (yield) and qualitatively (fatty acid profile) similar to those obtained using Soxhlet extraction (SE), but oil extracted by MAE exhibited favourable physicochemical properties and oxidation stability. Additionally, oil extracted by MAE had a higher content of total phenolic, and it showed stronger antioxidant activities. Scanning electron microscopy revealed that microwave technique efficiently promoted the release of oil by breaking down the cell structure of silkworm pupae. Therefore, MAE can be an effective method for the silkworm pupal oil extraction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Regeneration of 2-amino-2-methyl-1-propanol used for carbon dioxide absorption.

    PubMed

    Zhang, Pei; Shi, Yao; Wei, Jianwen; Zhao, Wei; Ye, Qing

    2008-01-01

    To improve the efficiency of the carbon dioxide cycling process and to reduce the regeneration energy consumption, a sterically hindered amine of 2-amino-2-methyl-1-propranol (AMP) was investigated to determine its regeneration behavior as a CO2 absorbent. The CO2 absorption and amine regeneration characteristics were experimentally examined under various operating conditions. The regeneration efficiency increased from 86.2% to 98.3% during the temperature range of 358 to 403 K. The most suitable regeneration temperature for AMP was 383 K, in this experiment condition, and the regeneration efficiency of absorption/regenerationruns descended from 98.3% to 94.0%. A number of heat-stable salts (HSS) could cause a reduction in CO2 absorption capacity and regeneration efficiency. The results indicated that aqueous AMP was easier to regenerate with less loss of absorption capacity than other amines, such as, monoethanolamine (MEA), diethanolamine (DEA), diethylenetriamine (DETA), and N-methyldiethanolamine (MDEA).

  5. Balancing Power Absorption Against Structural Loads With Viscous Drag and Power-Takeoff Efficiency Considerations

    DOE PAGES

    Tom, Nathan; Yu, Yi-Hsiang; Wright, Alan; ...

    2017-11-17

    The focus of this paper is to balance power absorption against structural loading for a novel fixed-bottom oscillating surge wave energy converter in both regular and irregular wave environments. The power-to-load ratio will be evaluated using pseudospectral control (PSC) to determine the optimum power-takeoff (PTO) torque based on a multiterm objective function. This paper extends the pseudospectral optimal control problem to not just maximize the time-averaged absorbed power but also include measures for the surge-foundation force and PTO torque in the optimization. The objective function may now potentially include three competing terms that the optimizer must balance. Separate weighting factorsmore » are attached to the surge-foundation force and PTO control torque that can be used to tune the optimizer performance to emphasize either power absorption or load shedding. To correct the pitch equation of motion, derived from linear hydrodynamic theory, a quadratic-viscous-drag torque has been included in the system dynamics; however, to continue the use of quadratic programming solvers, an iteratively obtained linearized drag coefficient was utilized that provided good accuracy in the predicted pitch motion. Furthermore, the analysis considers the use of a nonideal PTO unit to more accurately evaluate controller performance. The PTO efficiency is not directly included in the objective function but rather the weighting factors are utilized to limit the PTO torque amplitudes, thereby reducing the losses resulting from the bidirectional energy flow through a nonideal PTO. Results from PSC show that shedding a portion of the available wave energy can lead to greater reductions in structural loads, peak-to-average power ratio, and reactive power requirement.« less

  6. Impact of aerosol particle sources on optical properties in urban, regional and remote areas in the north-western Mediterranean

    NASA Astrophysics Data System (ADS)

    Ealo, Marina; Alastuey, Andrés; Pérez, Noemí; Ripoll, Anna; Querol, Xavier; Pandolfi, Marco

    2018-01-01

    Further research is needed to reduce the existing uncertainties on the effect that specific aerosol particle sources have on light extinction and consequently on climate. This study presents a new approach that aims to quantify the mass scattering and absorption efficiencies (MSEs and MAEs) of different aerosol sources at urban (Barcelona - BCN), regional (Montseny - MSY) and remote (Montsec - MSA) background sites in the north-western (NW) Mediterranean. An analysis of source apportionment to the measured multi-wavelength light scattering (σsp) and absorption (σap) coefficients was performed by means of a multilinear regression (MLR) model for the periods 2009-2014, 2010-2014 and 2011-2014 at BCN, MSY and MSA respectively. The source contributions to PM10 mass concentration, identified by means of the positive matrix factorization (PMF) model, were used as dependent variables in the MLR model. With this approach we addressed both the effect that aerosol sources have on air quality and their potential effect on light extinction through the determination of their MSEs and MAEs. An advantage of the presented approach is that the calculated MSEs and MAEs take into account the internal mixing of atmospheric particles. Seven aerosol sources were identified at MSA and MSY, and eight sources at BCN. Mineral, aged marine, secondary sulfate, secondary nitrate and V-Ni bearing sources were common at the three sites. Traffic, industrial/metallurgy and road dust resuspension sources were isolated at BCN, whereas mixed industrial/traffic and aged organics sources were identified at MSY and MSA. The highest MSEs were observed for secondary sulfate (4.5 and 10.7 m2 g-1, at MSY and MSA), secondary nitrate (8.8 and 7.8 m2 g-1) and V-Ni bearing source (8 and 3.5 m2 g-1). These sources dominated the scattering throughout the year with marked seasonal trends. The V-Ni bearing source, originating mainly from shipping in the area under study, simultaneously contributed to both

  7. Improved efficiency of perovskite-silicon tandem solar cell near the matched optical absorption between the subcells

    NASA Astrophysics Data System (ADS)

    Iftiquar, S. M.; Jung, Junhee; Yi, Junsin

    2017-10-01

    Current matching in a tandem solar cell is significant, because in a mismatched device the lowest current generating subcell becomes the current limiting component, and overall device efficiency remains lower than that could be obtained in the current matched device. Recent reports on methyl ammonium lead iodide (MAPbI3) based thin film solar cell has drawn interest to a perovskite-silicon tandem solar cell. Therefore, we investigated such a tandem solar cell theoretically. We used a MAPbI3 based top and heterojunction with intrinsic thin layer silicon (HIT) bottom subcell. Optimization of the device structure was carried out by varying thickness of perovskite layer of top-cell from 50 to 1000 nm, while thickness of active layer of the HIT cell was kept constant, to 500 µm. Single-junction solar cell, formed with the bottom subcell had open circuit voltage (V oc) of 705.1 mV, short circuit current density (J sc) of 28.22 mA cm-2, fill factor (FF) of 0.82 and efficiency of 16.4% under AM1.5G insolation. A relatively low thickness (150 nm) of the perovskite absorber layer was found optimum for the top-subcell to achieve best efficiency of the tandem cell, partly because of intermediate reflection at the interface between the two cells. We obtained a maximum of 20.92% efficiency of the tandem solar cell, which is higher by a factor of 1.27 from the starting HIT cell and a factor 1.47 higher from the perovskite cell efficiency. J sc of the optimized tandem cell was 13.06 mA cm-2. This was achieved near the matching optical absorption or current-density of the component subcells. For a practical application, the device used in our investigation was without textured front surface. An ordinary HIT bottom-cell was used with lower J sc. Therefore, with an improved HIT subcell, efficiency of the tandem cell, higher than 21% will be achievable.

  8. Spectral Absorption Properties of Aerosol Particles from 350-2500nm

    NASA Technical Reports Server (NTRS)

    Martins, J. Vanderlei; Artaxo, Paulo; Kaufman, Yoram J.; Castanho, Andrea D.; Remer, Lorraine A.

    2009-01-01

    The aerosol spectral absorption efficiency (alpha (sub a) in square meters per gram) is measured over an extended wavelength range (350 2500 nm) using an improved calibrated and validated reflectance technique and applied to urban aerosol samples from Sao Paulo, Brazil and from a site in Virginia, Eastern US, that experiences transported urban/industrial aerosol. The average alpha (sub a) values (approximately 3 square meters per gram at 550 nm) for Sao Paulo samples are 10 times larger than alpha (sub a) values obtained for aerosols in Virginia. Sao Paulo aerosols also show evidence of enhanced UV absorption in selected samples, probably associated with organic aerosol components. This extra UV absorption can double the absorption efficiency observed from black carbon alone, therefore reducing by up to 50% the surface UV fluxes, with important implications for climate, UV photolysis rates, and remote sensing from space.

  9. Screening of the Antimicrobial Activity against Drug Resistant Bacteria of Photorhabdus and Xenorhabdus Associated with Entomopathogenic Nematodes from Mae Wong National Park, Thailand

    PubMed Central

    Muangpat, Paramaporn; Yooyangket, Temsiri; Fukruksa, Chamaiporn; Suwannaroj, Manawat; Yimthin, Thatcha; Sitthisak, Sutthirat; Chantratita, Narisara; Vitta, Apichat; Tobias, Nicholas J.; Bode, Helge B.; Thanwisai, Aunchalee

    2017-01-01

    Photorhabdus and Xenorhabdus are symbiotic with entomopathogenic nematodes (EPNs) of the genera Heterorhabditis and Steinernema, respectively. These bacteria produce several secondary metabolites including antimicrobial compounds. The objectives of this study were to isolate and identify EPNs and their symbiotic bacteria from Mae Wong National Park, Thailand and to evaluate the antibacterial activities of symbiont extracts against drug resistant bacteria. A total of 550 soil samples from 110 sites were collected between August 2014 and July 2015. A total of EPN isolates were obtained through baiting and White trap methods, which yielded 21 Heterorhabditis and 3 Steinernema isolates. Based on molecular identification and phylogenetic analysis, the most common species found in the present study was P. luminescens subsp. akhurstii associated with H. indica. Notably, two species of EPNs, H. zealandica and S. kushidai, and two species of symbiotic bacteria, X. japonica and P. temperata subsp. temperata represented new recorded organisms in Thailand. Furthermore, the association between P. temperata subsp. temperata and H. zealandica has not previously been reported worldwide. Disk diffusion, minimal inhibitory concentration, and minimal bactericidal concentration analyses demonstrated that the crude compound extracted by ethyl acetate from P. temperata subsp. temperata could inhibit the growth of up to 10 strains of drug resistant bacteria. Based on HPLC-MS analysis, compound classes in bacterial extracts were identified as GameXPeptide, xenoamicin, xenocoumacin, mevalagmapeptide phurealipids derivatives, and isopropylstilbene. Together, the results of this study provide evidence for the diversity of EPNs and their symbiotic bacteria in Mae Wong National Park, Thailand and demonstrate their novel associations. These findings also provide an important foundation for further research regarding the antimicrobial activity of Photorhabdus bacteria. PMID:28702004

  10. High absorption coefficients of the CuSb(Se,Te)2 and CuBi(S,Se)2 alloys enable high-efficient 100 nm thin-film photovoltaics

    NASA Astrophysics Data System (ADS)

    Chen, Rongzhen; Persson, Clas

    2017-06-01

    We demonstrate that the band-gap energies Eg of CuSb(Se,Te)2 and CuBi(S,Se)2 can be optimized for high energy conversion in very thin photovoltaic devices, and that the alloys then exhibit excellent optical properties, especially for tellurium rich CuSb(Se1-xTex)2. This is explained by multi-valley band structure with flat energy dispersions, mainly due to the localized character of the Sb/Bi p-like conduction band states. Still the effective electron mass is reasonable small: mc ≈ 0.25m0 for CuSbTe2. The absorption coefficient α(ω) for CuSb(Se1-xTex)2 is at ħω = Eg + 1 eV as much as 5-7 times larger than α(ω) for traditional thin-film absorber materials. Auger recombination does limit the efficiency if the carrier concentration becomes too high, and this effect needs to be suppressed. However with high absorptivity, the alloys can be utilized for extremely thin inorganic solar cells with the maximum efficiency ηmax ≈ 25% even for film thicknesses d ≈ 50 - 150 nm, and the efficiency increases to ˜30% if the Auger effect is diminished.

  11. Effect of idler absorption in pulsed optical parametric oscillators.

    PubMed

    Rustad, Gunnar; Arisholm, Gunnar; Farsund, Øystein

    2011-01-31

    Absorption at the idler wavelength in an optical parametric oscillator (OPO) is often considered detrimental. We show through simulations that pulsed OPOs with significant idler absorption can perform better than OPOs with low idler absorption both in terms of conversion efficiency and beam quality. The main reason for this is reduced back conversion. We also show how the beam quality depends on the beam width and pump pulse length, and present scaling relations to use the example simulations for other pulsed nanosecond OPOs.

  12. Effects of chronic metal exposure and sediment organic matter on digestive absorption efficiency of cadmium by the deposit-feeding polychaete Capitella species I

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

    Selck, H.; Forbes, V.E.; Decho, A.W.

    1999-06-01

    Organic matter such as humic acid and bacterial slime exopolymer are common in estuarine and coastal sediments, where they are ingested by animals that process particulate detritus. Both humic acid (HA; refractory) and exopolymer (EPS; easily digestible) bind metals and therefore might represent a source of particulate-bound metals to deposit-feeding organisms. This study examined how cadmium preexposure, gut passage time (GPT), and quality and quantity of the organic coating on sediment particles interact to determine cadmium absorption efficiency (Cd-AE) in Capitella sp. I. Pulse-chase experiments using [sup 109]Cd and [sup 51]Cr were used to determine Cd-AE in individual worms. Wormsmore » were given a pulse of carbon-cleaned, HA-coated or EPS-coated sediment particles. The third treatment was divided into three EPS concentrations (high, medium, and low). A 5-d preexposure to cadmium did not affect the egestion rates during either the preexposure period or the chase phase. Worms given a pulse of carbon-cleaned particles exhibited higher egestion rates during the chase phase than worms given a pulse of organic-coated particles, and no differences were seen in egestion rate between worms exposed to HA- and high-EPS-coated particles. Egestion rates decreased with increasing EPS concentration. The presence of refractory organic material decreased the absorption efficiency of cadmium from sediment relative to Cd-AE from carbon-cleaned sediment but not relative to Cd-AE from sediment coated with a high concentration of EPS. The Cd-AE increased linearly with increasing exopolymer coating on sediment particles. Overall, Cd-AE increased with increasing gut passage time in worms that were not preexposed, although Cd-AE from HA-coated particles was independent of gut passage time. Preexposure to cadmium reversed the relationship between gut passage time and cadmium absorption efficiency. Thus, the implications are that sedimentary organic matter and worm physiology might

  13. Evaluation of absorption cycle for space station environmental control system application

    NASA Technical Reports Server (NTRS)

    Sims, W. H.; Oneill, M. J.; Reid, H. C.; Bisenius, P. M.

    1972-01-01

    The study to evaluate an absorption cycle refrigeration system to provide environmental control for the space stations is reported. A zero-gravity liquid/vapor separator was designed and tested. The results were used to design a light-weight, efficient generator for the absorption refrigeration system. It is concluded that absorption cycle refrigeration is feasible for providing space station environmental control.

  14. Efficient atom localization via probe absorption in an inverted-Y atomic system

    NASA Astrophysics Data System (ADS)

    Wu, Jianchun; Wu, Bo; Mao, Jiejian

    2018-06-01

    The behaviour of atom localization in an inverted-Y atomic system is theoretically investigated. For the atoms interacting with a weak probe field and several orthogonal standing-wave fields, their position information can be obtained by measuring the probe absorption. Compared with the traditional scheme, we couple the probe field to the transition between the middle and top levels. It is found that the probe absorption sensitively depends on the detuning and strength of the relevant light fields. Remarkably, the atom can be localized at a particular position in the standing-wave fields by coupling a microwave field to the transition between the two ground levels.

  15. Oversight of Student Loan Marketing Association (Sallie Mae). Hearing Before the Subcommittee on Education, Arts and Humanities of the Committee on Labor and Human Resources. United States Senate, Ninety-Seventh Congress, Second Session.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. Senate Committee on Labor and Human Resources.

    Hearings concerning the activities of the Student Loan Marketing Association (Sallie Mae) are presented. Attention is focused on a request for an exemption under federal priority for recovering money owed the Association in the event that it files for liquidation or reorganization in the future under the Bankruptcy Act. It is noted that two goals…

  16. Multijunction solar cell design revisited: disruption of current matching by atmospheric absorption bands: Disruption of current matching by atmospheric absorption bands

    DOE PAGES

    McMahon, William E.; Friedman, Daniel J.; Geisz, John F.

    2017-05-23

    This paper re-examines the impact of atmospheric absorption bands on series-connected multijunction cell design, motivated by the numerous local efficiency maxima that appear as the number of junctions is increased. Some of the local maxima are related to the bottom subcell bandgap and are already well understood: As the bottom subcell bandgap is varied, a local efficiency maximum is produced wherever the bottom cell bandgap crosses an atmospheric absorption band. The optimal cell designs at these local maxima are generally current matched, such that all subcells have nearly the same short-circuit current. We systematically describe additional local maxima that occurmore » wherever an upper subcell bandgap encounters an atmospheric absorption band. Moreover, these local maxima are not current matched and become more prevalent as the number of junctions increases, complicating the solution space for five-junction and six-junction designs. A systematic framework for describing this complexity is developed, and implications for numerical convergence are discussed.« less

  17. Multijunction solar cell design revisited: disruption of current matching by atmospheric absorption bands: Disruption of current matching by atmospheric absorption bands

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

    McMahon, William E.; Friedman, Daniel J.; Geisz, John F.

    This paper re-examines the impact of atmospheric absorption bands on series-connected multijunction cell design, motivated by the numerous local efficiency maxima that appear as the number of junctions is increased. Some of the local maxima are related to the bottom subcell bandgap and are already well understood: As the bottom subcell bandgap is varied, a local efficiency maximum is produced wherever the bottom cell bandgap crosses an atmospheric absorption band. The optimal cell designs at these local maxima are generally current matched, such that all subcells have nearly the same short-circuit current. We systematically describe additional local maxima that occurmore » wherever an upper subcell bandgap encounters an atmospheric absorption band. Moreover, these local maxima are not current matched and become more prevalent as the number of junctions increases, complicating the solution space for five-junction and six-junction designs. A systematic framework for describing this complexity is developed, and implications for numerical convergence are discussed.« less

  18. Hydrolysis Batteries: Generating Electrical Energy during Hydrogen Absorption.

    PubMed

    Xiao, Rui; Chen, Jun; Fu, Kai; Zheng, Xinyao; Wang, Teng; Zheng, Jie; Li, Xingguo

    2018-02-19

    The hydrolysis reaction of aluminum can be decoupled into a battery by pairing an Al foil with a Pd-capped yttrium dihydride (YH 2 -Pd) electrode. This hydrolysis battery generates a voltage around 0.45 V and leads to hydrogen absorption into the YH 2 layer. This represents a new hydrogen absorption mechanism featuring electrical energy generation during hydrogen absorption. The hydrolysis battery converts 8-15 % of the thermal energy of the hydrolysis reaction into usable electrical energy, leading to much higher energy efficiency compared to that of direct hydrolysis. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. High-speed homogenization coupled with microwave-assisted extraction followed by liquid chromatography-tandem mass spectrometry for the direct determination of alkaloids and flavonoids in fresh Isatis tinctoria L. hairy root cultures.

    PubMed

    Jiao, Jiao; Gai, Qing-Yan; Zhang, Lin; Wang, Wei; Luo, Meng; Zu, Yuan-Gang; Fu, Yu-Jie

    2015-06-01

    A new, simple and efficient analysis method for fresh plant in vitro cultures-namely, high-speed homogenization coupled with microwave-assisted extraction (HSH-MAE) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS)-was developed for simultaneous determination of six alkaloids and eight flavonoids in Isatis tinctoria hairy root cultures (ITHRCs). Compared with traditional methods, the proposed HSH-MAE offers the advantages of easy manipulation, higher efficiency, energy saving, and reduced waste. Cytohistological studies were conducted to clarify the mechanism of HSH-MAE at cellular/tissue levels. Moreover, the established LC-MS/MS method showed excellent linearity, precision, repeatability, and reproducibility. The HSH-MAE-LC-MS/MS method was also successfully applied for screening high-productivity ITHRCs. Overall, this study opened up a new avenue for the direct determination of secondary metabolic profiles from fresh plant in vitro cultures, which is valuable for improving quality control of plant cell/organ cultures and sheds light on the metabolomic analysis of biological samples. Graphical Abstract HSH-MAE-LC-MS/MS opened up a new avenue for the direct determination of alkaloids and flavonoids in fresh Isatis tinctoria hairy root cultures.

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

    NASA Astrophysics Data System (ADS)

    Sichan, N.

    2007-12-01

    This study was aimed to understand the nature of the resistivity value of the sediment when it is contaminated, in order to use the information solving the obscure interpretation in the field. The pilot laboratory experiments were designed to simulate various degree of contamination and degree of saturation then observe the resulting changes in resistivity. The study was expected to get a better understanding of how various physical parameters effect the resistivity values in term of mathematic function. And also expected to apply those obtained function to a practical quantitatively interpretation. The sediment underlying the Mae-Hia Landfill consists of clay-rich material, with interfingerings of colluvium and sandy alluvium. A systematic study identified four kinds of sediment, sand, clayey sand, sandy clay, and clay. Representative sediment and leachate samples were taken from the field and returned to the laboratory. Both the physical and chemical properties of the sediments and leachate were analyzed to delineate the necessary parameters that could be used in Archie's equation. Sediment samples were mixed with various concentration of leachate solutions. Then the resistivity values were measured at various controlled steps in the saturation degree in a well- calibrated six-electrode model resistivity box. The measured resistivity values for sand, clayey sand, sandy clay when fully and partly saturated were collected, then plotted and fitted to Archie's equation, to obtain a mathematical relationship between bulk resistivity, porosity, saturation degree and resistivity of pore fluid. The results fit well to Archie's equation, and it was possible to determine all the unknown parameters representative of the sediment samples. For sand, clayey sand, sandy clay, and clay, the formation resistivity factors (F) are 2.90, 5.77, 7.85, and 7.85 with the products of cementation factor (m) and the pore geometry factors (a) (in term of -am) are 1.49, -1.63, -1.92, -2

  1. High sensitivity background absorption measurements in semiconductors

    NASA Astrophysics Data System (ADS)

    Giannini, Nathan; Silva, Junior R.; Wang, Chengao; Albrecht, Alexander R.; Melgaard, Seth D.; Sheik-Bahae, Mansoor

    2015-03-01

    Laser cooling in InGaP|GaAs double heterostructures (DHS) has been a sought after goal. Even though very high external quantum efficiency (EQE) has been achieved, background absorption has remained a bottleneck in achieving net cooling. The purpose of this study is to gain more insight into the source of the background absorption for InGaP|GaAs DHS as well as GaAs|AlGaAs DBRs by employing an excite-probe thermal Z-scan measurement.

  2. Extraction of polycyclic aromatic hydrocarbons and organochlorine pesticides from soils: a comparison between Soxhlet extraction, microwave-assisted extraction and accelerated solvent extraction techniques.

    PubMed

    Wang, Wentao; Meng, Bingjun; Lu, Xiaoxia; Liu, Yu; Tao, Shu

    2007-10-29

    The methods of simultaneous extraction of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) from soils using Soxhlet extraction, microwave-assisted extraction (MAE) and accelerated solvent extraction (ASE) were established, and the extraction efficiencies using the three methods were systemically compared from procedural blank, limits of detection and quantification, method recovery and reproducibility, method chromatogram and other factors. In addition, soils with different total organic carbon contents were used to test the extraction efficiencies of the three methods. The results showed that the values obtained in this study were comparable with the values reported by other studies. In some respects such as method recovery and reproducibility, there were no significant differences among the three methods for the extraction of PAHs and OCPs. In some respects such as procedural blank and limits of detection and quantification, there were significant differences among the three methods. Overall, ASE had the best extraction efficiency compared to MAE and Soxhlet extraction, and the extraction efficiencies of MAE and Soxhlet extraction were comparable to each other depending on the property such as TOC content of the studied soil. Considering other factors such as solvent consumption and extraction time, ASE and MAE are preferable to Soxhlet extraction.

  3. Tailoring perovskite compounds for broadband light absorption

    NASA Astrophysics Data System (ADS)

    Lu, Hengchang; Guo, Xiaowei; Yang, Cheng; Li, Shaorong

    2018-01-01

    Perovskite solar cells have experienced an outstanding advance in power conversion efficiency (PCE) by optimizing the perovskite layer morphology, composition, interfaces, and charge collection efficiency. To enhance PCE, the mixed perovskites were proposed in recent years. In this study, optoelectronic performance of pure perovskites and mixed ones were investigated. It was demonstrated that the mixed perovskites exhibit superior to the pure ones. The mixed material can absorb broadband light absorption and result in increased short circuit current density and power conversion efficiency.

  4. Timing of metamorphism of the Lansang gneiss and implications for left-lateral motion along the Mae Ping (Wang Chao) strike-slip fault, Thailand

    NASA Astrophysics Data System (ADS)

    Palin, R. M.; Searle, M. P.; Morley, C. K.; Charusiri, P.; Horstwood, M. S. A.; Roberts, N. M. W.

    2013-10-01

    The Mae Ping fault (MPF), western Thailand, exhibits dominantly left-lateral strike-slip motion and stretches for >600 km, reportedly branching off the right-lateral Sagaing fault in Myanmar and extending southeast towards Cambodia. Previous studies have suggested that the fault assisted the large-scale extrusion of Sundaland that occurred during the Late Eocene-Early Oligocene, with a geological offset of ˜120-150 km estimated from displaced high-grade gneisses and granites of the Chiang Mai-Lincang belt. Exposures of high-grade orthogneiss in the Lansang National Park, part of this belt, locally contain strong mylonitic textures and are bounded by strike-slip ductile shear zones and brittle faults. Geochronological analysis of monazite from a sample of sheared biotite-K-feldspar orthogneiss suggests two episodes of crystallization, with core regions documenting Th-Pb ages between c. 123 and c. 114 Ma and rim regions documenting a significantly younger age range between c. 45-37 Ma. These data are interpreted to represent possible magmatic protolith emplacement for the Lansang orthogneiss during the Early Cretaceous, with a later episode of metamorphism occurring during the Eocene. Textural relationships provided by in situ analysis suggest that ductile shearing along the MPF occurred during the latter stages of, or after, this metamorphic event. In addition, monazite analyzed from an undeformed garnet-two-mica granite dyke intruding metamorphic units at Bhumipol Lake outside of the Mae Ping shear zone produced a Th-Pb age of 66.2 ± 1.6 Ma. This age is interpreted to date the timing of dyke emplacement, implying that the MPF cuts through earlier formed magmatic and high-grade metamorphic rocks. These new data, when combined with regional mapping and earlier geochronological work, show that neither metamorphism, nor regional cooling, was directly related to strike-slip motion.

  5. 9.73% Efficiency Nonfullerene All Organic Small Molecule Solar Cells with Absorption-Complementary Donor and Acceptor.

    PubMed

    Bin, Haijun; Yang, Yankang; Zhang, Zhi-Guo; Ye, Long; Ghasemi, Masoud; Chen, Shanshan; Zhang, Yindong; Zhang, Chunfeng; Sun, Chenkai; Xue, Lingwei; Yang, Changduk; Ade, Harald; Li, Yongfang

    2017-03-29

    In the last two years, polymer solar cells (PSCs) developed quickly with n-type organic semiconductor (n-OSs) as acceptor. In contrast, the research progress of nonfullerene organic solar cells (OSCs) with organic small molecule as donor and the n-OS as acceptor lags behind. Here, we synthesized a D-A structured medium bandgap organic small molecule H11 with bithienyl-benzodithiophene (BDTT) as central donor unit and fluorobenzotriazole as acceptor unit, and achieved a power conversion efficiency (PCE) of 9.73% for the all organic small molecules OSCs with H11 as donor and a low bandgap n-OS IDIC as acceptor. A control molecule H12 without thiophene conjugated side chains on the BDT unit was also synthesized for investigating the effect of the thiophene conjugated side chains on the photovoltaic performance of the p-type organic semiconductors (p-OSs). Compared with H12, the 2D-conjugated H11 with thiophene conjugated side chains shows intense absorption, low-lying HOMO energy level, higher hole mobility and ordered bimodal crystallite packing in the blend films. Moreover, a larger interaction parameter (χ) was observed in the H11 blends calculated from Hansen solubility parameters and differential scanning calorimetry measurements. These special features combined with the complementary absorption of H11 donor and IDIC acceptor resulted in the best PCE of 9.73% for nonfullerene all small molecule OSCs up to date. Our results indicate that fluorobenzotriazole based 2D conjugated p-OSs are promising medium bandgap donors in the nonfullerene OSCs.

  6. Laser-induced plasma characterization through self-absorption quantification

    NASA Astrophysics Data System (ADS)

    Hou, JiaJia; Zhang, Lei; Zhao, Yang; Yan, Xingyu; Ma, Weiguang; Dong, Lei; Yin, Wangbao; Xiao, Liantuan; Jia, Suotang

    2018-07-01

    A self-absorption quantification method is proposed to quantify the self-absorption degree of spectral lines, in which plasma characteristics including electron temperature, elemental concentration ratio, and absolute species number density can be deduced directly. Since there is no spectral intensity involved in the calculation, the analysis results are independent of the self-absorption effects and the additional spectral efficiency calibration is not required. In order to evaluate the practicality, the limitation for application and the precision of this method are also discussed. Experimental results of aluminum-lithium alloy prove that the proposed method is qualified to realize semi-quantitative measurements and fast plasma characteristics diagnostics.

  7. Ultra-thin enhanced-absorption long-wave infrared detectors

    NASA Astrophysics Data System (ADS)

    Wang, Shaohua; Yoon, Narae; Kamboj, Abhilasha; Petluru, Priyanka; Zheng, Wanhua; Wasserman, Daniel

    2018-02-01

    We propose an architecture for enhanced absorption in ultra-thin strained layer superlattice detectors utilizing a hybrid optical cavity design. Our detector architecture utilizes a designer-metal doped semiconductor ground plane beneath the ultra-subwavelength thickness long-wavelength infrared absorber material, upon which we pattern metallic antenna structures. We demonstrate the potential for near 50% detector absorption in absorber layers with thicknesses of approximately λ0/50, using realistic material parameters. We investigate detector absorption as a function of wavelength and incidence angle, as well as detector geometry. The proposed device architecture offers the potential for high efficiency detectors with minimal growth costs and relaxed design parameters.

  8. Current fluctuations in quantum absorption refrigerators

    NASA Astrophysics Data System (ADS)

    Segal, Dvira

    2018-05-01

    Absorption refrigerators transfer thermal energy from a cold bath to a hot bath without input power by utilizing heat from an additional "work" reservoir. Particularly interesting is a three-level design for a quantum absorption refrigerator, which can be optimized to reach the maximal (Carnot) cooling efficiency. Previous studies of three-level chillers focused on the behavior of the averaged cooling current. Here, we go beyond that and study the full counting statistics of heat exchange in a three-level chiller model. We explain how to obtain the complete cumulant generating function of the refrigerator in a steady state, then derive a partial cumulant generating function, which yields closed-form expressions for both the averaged cooling current and its noise. Our analytical results and simulations are beneficial for the design of nanoscale engines and cooling systems far from equilibrium, with their performance optimized according to different criteria, efficiency, power, fluctuations, and dissipation.

  9. Robust electromagnetic absorption by graphene/polymer heterostructures

    NASA Astrophysics Data System (ADS)

    Lobet, Michaël; Reckinger, Nicolas; Henrard, Luc; Lambin, Philippe

    2015-07-01

    Polymer/graphene heterostructures present good shielding efficiency against GHz electromagnetic perturbations. Theory and experiments demonstrate that there is an optimum number of graphene planes, separated by thin polymer spacers, leading to maximum absorption for millimeter waves Batrakov et al (2014 Sci. Rep. 4 7191). Here, electrodynamics of ideal polymer/graphene multilayered material is first approached with a well-adapted continued-fraction formalism. In a second stage, rigorous coupled wave analysis is used to account for the presence of defects in graphene that are typical of samples produced by chemical vapor deposition, namely microscopic holes, microscopic dots (embryos of a second layer) and grain boundaries. It is shown that the optimum absorbance of graphene/polymer multilayers does not weaken to the first order in defect concentration. This finding testifies to the robustness of the shielding efficiency of the proposed absorption device.

  10. An absorbing microwave micro-solid-phase extraction device used in non-polar solvent microwave-assisted extraction for the determination of organophosphorus pesticides.

    PubMed

    Wang, Ziming; Zhao, Xin; Xu, Xu; Wu, Lijie; Su, Rui; Zhao, Yajing; Jiang, Chengfei; Zhang, Hanqi; Ma, Qiang; Lu, Chunmei; Dong, Deming

    2013-01-14

    A single-step extraction-cleanup method, including microwave-assisted extraction (MAE) and micro-solid-phase extraction (μ-SPE), was developed for the extraction of ten organophosphorus pesticides in vegetable and fruit samples. Without adding any polar solvent, only one kind of non-polar solvent (hexane) was used as extraction solvent in the whole extraction step. Absorbing microwave μ-SPE device, was prepared by packing activated carbon with microporous polypropylene membrane envelope, and used as not only the sorbent in μ-SPE, but also the microwave absorption medium. Some experimental parameters effecting on extraction efficiency was investigated and optimized. 1.0 g of sample, 8 mL of hexane and three absorbing microwave μ-SPE devices were added in the microwave extraction vessel, the extraction was carried out under 400 W irradiation power at 60°C for 10 min. The extracts obtained by MAE-μ-SPE were directly analyzed by GC-MS without any clean-up process. The recoveries were in the range of 93.5-104.6%, and the relative standard deviations were lower than 8.7%. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. The efficiency of utilization of metabolizable energy and apparent absorption of amino acids in sheep given spring- and autumn-harvested dried grass.

    PubMed

    Macrae, J C; Smith, J S; Dewey, P J; Brewer, A C; Brown, D S; Walker, A

    1985-07-01

    Three experiments were conducted with sheep given spring-harvested dried grass (SHG) and autumn-harvested dried grass (AHG). The first was a calorimetric trial to determine the metabolizable energy (ME) content of each grass and the efficiency with which sheep utilize their extra ME intakes above the maintenance level of intake. The second examined the relative amounts of extra non-ammonia-nitrogen (NAN) and individual amino acids absorbed from the small intestine per unit extra ME intake as the level of feeding was raised from energy equilibrium (M) to approximately 1.5 M. The third was a further calorimetric trial to investigate the effect of an abomasal infusion of 30 g casein/d on the efficiency of utilization of AHG. The ME content of the SHG (11.8 MJ/kg dry matter (DM] was higher than that of AHG (10.0 MJ/kg DM). The efficiency of utilization of ME for productive purposes (i.e. above the M level of intake; kf) was higher when given SHG (kf 0.54 between M and 2 M) than when given AHG (kf 0.43 between M and 2 M). As the level of intake of each grass was raised from M to 1.5 M there was a greater increment in the amounts of NAN (P less than 0.001) and the total amino acid (P less than 0.05) absorbed from the small intestines when sheep were given the SHG (NAN absorption, SHG 5.4 g/d, AHG 1.5 g/d, SED 0.54; total amino acid absorption SHG 31.5 g/d, AHG 14.3 g/d, SED 5.24). Infusion of 30 g casein/d per abomasum of sheep given AHG at M and 1.5 M levels of intake increased (P less than 0.05) the efficiency of utilization of the herbage from kf 0.45 to kf 0.57. Consideration is given to the possibility that the higher efficiency of utilization of ME in sheep given SHG may be related to the amounts of extra glucogenic amino acids absorbed from the small intestine which provide extra reducing equivalents (NADPH) and glycerol phosphate necessary for the conversion of acetate into fatty acids.

  12. Absorption, scattering, and radiation force efficiencies in the longitudinal wave scattering by a small viscoelastic particle in an isotropic solid.

    PubMed

    Lopes, J H; Leão-Neto, J P; Silva, G T

    2017-11-01

    Analytical expressions of the absorption, scattering, and elastic radiation force efficiency factors are derived for the longitudinal plane wave scattering by a small viscoelastic particle in a lossless solid matrix. The particle is assumed to be much smaller than the incident wavelength, i.e., the so-called long-wavelength (Rayleigh) approximation. The efficiencies are dimensionless quantities that represent the absorbed and scattering powers and the elastic radiation force on the particle. In the quadrupole approximation, they are expressed in terms of contrast functions (bulk and shear moduli, and density) between the particle and solid matrix. The results for a high-density polyethylene particle embedded in an aluminum matrix agree with those obtained with the partial wave expansion method. Additionally, the connection between the elastic radiation force and forward scattering function is established through the optical theorem. The present results should be useful for ultrasound characterization of particulate composites, and the development of implanted devices activated by radiation force.

  13. Radiant energy absorption studies for laser propulsion. [gas dynamics

    NASA Technical Reports Server (NTRS)

    Caledonia, G. E.; Wu, P. K. S.; Pirri, A. N.

    1975-01-01

    A study of the energy absorption mechanisms and fluid dynamic considerations for efficient conversion of high power laser radiation into a high velocity flow is presented. The objectives of the study are: (1) to determine the most effective absorption mechanisms for converting laser radiation into translational energy, and (2) to examine the requirements for transfer of the absorbed energy into a steady flow which is stable to disturbances in the absorption zone. A review of inverse Bremsstrahlung, molecular and particulate absorption mechanisms is considered and the steady flow and stability considerations for conversion of the laser power to a high velocity flow in a nozzle configuration is calculated. A quasi-one-dimensional flow through a nozzle was formulated under the assumptions of perfect gas.

  14. High-efficiency, broad-band and wide-angle optical absorption in ultra-thin organic photovoltaic devices.

    PubMed

    Wang, Wenyan; Hao, Yuying; Cui, Yanxia; Tian, Ximin; Zhang, Ye; Wang, Hua; Shi, Fang; Wei, Bin; Huang, Wei

    2014-03-10

    Metal nanogratings as one of the promising architectures for effective light trapping in organic photovoltaics (OPVs) have been actively studied over the past decade. Here we designed a novel metal nanowall grating with ultra-small period and ultra-high aspect-ratio as the back electrode of the OPV device. Such grating results in the strong hot spot effect in-between the neighboring nanowalls and the localized surface plasmon effect at the corners of nanowalls. These combined effects make the integrated absorption efficiency of light over the wavelength range from 400 to 650 nm in the active layer for the proposed structure, with respect to the equivalent planar structure, increases by 102% at TM polarization and by 36.5% at the TM/TE hybrid polarization, respectively. Moreover, it is noted that the hot spot effect in the proposed structure is more effective for ultra-thin active layers, which is very favorable for the exciton dissociation and charge collection. Therefore such a nanowall grating is expected to improve the overall performance of OPV devices.

  15. Microwave-assisted extraction with water for fast extraction and simultaneous RP-HPLC determination of phenolic acids in radix Salviae Miltiorrhizae.

    PubMed

    Fang, Xinsheng; Wang, Jianhua; Zhou, Hongying; Jiang, Xingkai; Zhu, Lixiang; Gao, Xin

    2009-07-01

    An optimized microwave-assisted extraction method using water (MAE-W) as the extractant and an efficient HPLC analysis method were first developed for the fast extraction and simultaneous determination of D(+)-(3,4-dihydroxyphenyl) lactic acid (Dla), salvianolic acid B (SaB), and lithospermic acid (La) in radix Salviae Miltiorrhizae. The key parameters of MAE-W were optimized. It was found that the degradation of SaB was inhibited when using the optimized MAE-W and the stable content of Dla, La, and SaB in danshen was obtained. Furthermore, compared to the conventional extraction methods, the proposed MAE-W is a more rapid method with higher yield and lower solvent consumption with a reproducibility (RSD <6%). In addition, using water as extractant is safe and helpful for environment protection, which could be referred to as green extraction. The separation and quantitative determination of the three compounds was carried out by a developed reverse-phase high-performance liquid chromatographic (RP-HPLC) method with UV detection. Highly efficient separation was obtained using gradient solvent system. The optimized HPLC analysis method was validated to have specificity, linearity, precision, and accuracy. The results indicated that MAE-W followed by HPLC-UV determination is an appropriate alternative to previously proposed method for quality control of radix Salviae Miltiorrhizae.

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

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

    Chen, Yuqing; Elshobaki, Moneim; Ye, Zhuo

    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 increasedmore » 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.« less

  17. Nonequilibrium gas absorption in rotating permeable media

    NASA Astrophysics Data System (ADS)

    Baev, V. K.; Bazhaikin, A. N.

    2016-08-01

    The absorption of ammonia, sulfur dioxide, and carbon dioxide by water and aqueous solutions in rotating permeable media, a cellular porous disk, and a set of spaced-apart thin disks has been considered. The efficiency of cleaning air to remove these impurities is determined, and their anomalously high solubility (higher than equilibrium value) has been discovered. The results demonstrate the feasibility of designing cheap efficient rotor-type absorbers to clean gases of harmful impurities.

  18. Scramjet Performance Assessment Using Water Absorption Diagnostics (U)

    NASA Technical Reports Server (NTRS)

    Cavolowsky, John A.; Loomis, Mark P.; Deiwert, George

    1995-01-01

    Simultaneous multiple path measurements of temperature and H2O concentration will be presented for the AIMHYE test entries in the NASA Ames 16-Inch Shock Tunnel. Monitoring the progress of high temperature chemical reactions that define scramjet combustor efficiencies is a task uniquely suited to nonintrusive optical diagnostics. One application strategy to overcome the many challenges and limitations of nonintrusive measurements is to use laser absorption spectroscopy coupled with optical fibers. Absorption spectroscopic techniques with rapidly tunable lasers are capable of making simultaneous measurements of mole fraction, temperature, pressure, and velocity. The scramjet water absorption diagnostic was used to measure combustor efficiency and was compared to thrust measurements using a nozzle force balance and integrated nozzle pressures to develop a direct technique for evaluating integrated scramjet performance. Tests were initially performed with a diode laser tuning over a water absorption feature at 1391.7 nm. A second diode laser later became available at a wavelength near 1343.3 nm covering an additional water absorption feature and was incorporated in the system for a two-wavelength technique. Both temperature and mole fraction can be inferred from the lineshape analysis using this approach. Additional high temperature spectroscopy research was conducted to reduce uncertainties in the scramjet application. The lasers are optical fiber coupled to ports at the combustor exit and in the nozzle region. The output from the two diode lasers were combined in a single fiber, and the resultant two-wavelength beam was subsequently split into four legs. Each leg was directed through 60 meters of optical fiber to four combustor exit locations for measurement of beam intensity after absorption by the water within the flow. Absorption results will be compared to 1D combustor analysis using RJPA and nozzle CFD computations as well as to data from a nozzle metric

  19. 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.

  20. Efficiency limits for photoelectrochemical water-splitting

    DOE PAGES

    Fountaine, Katherine T.; Lewerenz, Hans Joachim; Atwater, Harry A.

    2016-12-02

    Theoretical limiting efficiencies have a critical role in determining technological viability and expectations for device prototypes, as evidenced by the photovoltaics community’s focus on detailed balance. However, due to their multicomponent nature, photoelectrochemical devices do not have an equivalent analogue to detailed balance, and reported theoretical efficiency limits vary depending on the assumptions made. Here we introduce a unified framework for photoelectrochemical device performance through which all previous limiting efficiencies can be understood and contextualized. Ideal and experimentally realistic limiting efficiencies are presented, and then generalized using five representative parameters—semiconductor absorption fraction, external radiative efficiency, series resistance, shunt resistance andmore » catalytic exchange current density—to account for imperfect light absorption, charge transport and catalysis. Finally, we discuss the origin of deviations between the limits discussed herein and reported water-splitting efficiencies. This analysis provides insight into the primary factors that determine device performance and a powerful handle to improve device efficiency.« less

  1. Efficient Algorithms for Estimating the Absorption Spectrum within Linear Response TDDFT

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

    Brabec, Jiri; Lin, Lin; Shao, Meiyue

    We present a special symmetric Lanczos algorithm and a kernel polynomial method (KPM) for approximating the absorption spectrum of molecules within the linear response time-dependent density functional theory (TDDFT) framework in the product form. In contrast to existing algorithms, the new algorithms are based on reformulating the original non-Hermitian eigenvalue problem as a product eigenvalue problem and the observation that the product eigenvalue problem is self-adjoint with respect to an appropriately chosen inner product. This allows a simple symmetric Lanczos algorithm to be used to compute the desired absorption spectrum. The use of a symmetric Lanczos algorithm only requires halfmore » of the memory compared with the nonsymmetric variant of the Lanczos algorithm. The symmetric Lanczos algorithm is also numerically more stable than the nonsymmetric version. The KPM algorithm is also presented as a low-memory alternative to the Lanczos approach, but the algorithm may require more matrix-vector multiplications in practice. We discuss the pros and cons of these methods in terms of their accuracy as well as their computational and storage cost. Applications to a set of small and medium-sized molecules are also presented.« less

  2. Efficient Algorithms for Estimating the Absorption Spectrum within Linear Response TDDFT

    DOE PAGES

    Brabec, Jiri; Lin, Lin; Shao, Meiyue; ...

    2015-10-06

    We present a special symmetric Lanczos algorithm and a kernel polynomial method (KPM) for approximating the absorption spectrum of molecules within the linear response time-dependent density functional theory (TDDFT) framework in the product form. In contrast to existing algorithms, the new algorithms are based on reformulating the original non-Hermitian eigenvalue problem as a product eigenvalue problem and the observation that the product eigenvalue problem is self-adjoint with respect to an appropriately chosen inner product. This allows a simple symmetric Lanczos algorithm to be used to compute the desired absorption spectrum. The use of a symmetric Lanczos algorithm only requires halfmore » of the memory compared with the nonsymmetric variant of the Lanczos algorithm. The symmetric Lanczos algorithm is also numerically more stable than the nonsymmetric version. The KPM algorithm is also presented as a low-memory alternative to the Lanczos approach, but the algorithm may require more matrix-vector multiplications in practice. We discuss the pros and cons of these methods in terms of their accuracy as well as their computational and storage cost. Applications to a set of small and medium-sized molecules are also presented.« less

  3. Hybrid silicon–carbon nanostructures for broadband optical absorption

    DOE PAGES

    Yang, Wen -Hua; Lu, Wen -Cai; Ho, K. M.; ...

    2017-01-25

    Proper design of nanomaterials for broadband light absorption is a key factor for improving the conversion efficiency of solar cells. Here we present a hybrid design of silicon–carbon nanostructures with silicon clusters coated by carbon cages, i.e., Si m@C 2n for potential solar cell application. The optical properties of these hybrid nanostructures were calculated based on time dependent density function theory (TDDFT). The results show that the optical spectra of Si m@C 2n are very different from those of pure Si m and C 2n clusters. While the absorption spectra of pure carbon cages and Si m clusters exhibit peaksmore » in the UV region, those of the Si m@C 2n nanostructures exhibit a significant red shift. Superposition of the optical spectra of various Si m@C 2n nanostructures forms a broad-band absorption, which extends to the visible light and infrared regions. As a result, the broadband adsorption of the assembled Si m@C 2n nanoclusters may provide a new approach for the design of high efficiency solar cell nanomaterials.« less

  4. Geochemistry and mineralogy of fly-ash from the Mae Moh lignite deposit, Thailand

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

    Hart, B.R.; Powell, M.A.; Fyfe, W.S.

    The concentration of 21 elements in fly ash from three boilers (75 MW, 150 MW, and 300 MW) at the EGAT power plant, Mae Moh, Thailand, were determined by INAA. The concentration of 10 major elements was determined by XRF. As, Co, Cr, Ni, Mo, and Sb generally increase in concentration going from bottom ash (BA) through the sequence of electrostatic precipitator ashes (ESPA) and reach maxima of As (352 ppm), Co (45 ppm), Cr (105 ppm), Mo (32 ppm), Ni (106 ppm), and Sb (15 ppm) in the ESPA. Ce, Cs, Fe, Hf, La, Sc, Ta, Tb, and Ybmore » did not exhibit concentration trends or are variable except in the case of one boiler, which showed an increase going from BA to ESPA. Only Br decreased in composition going from BA to ESPA. Rb, Sm, U, and Th showed marked variation in trends. The major elements identified by EDS were Al, Si, S, K, Ca, Fe, and Ba, with minor amounts of Mg, Na, Ti, Mn, and Sr. Al, Si, K, and Ca occur together and are present in most of the fly-ash particles. Ba was found as a major component with Ca, Al, and Si. Fe and Ca are usually associated with sulfur. Some small spheres (< 5 {mu}m) are comprised almost entirely of Fe (probably as oxide). Symplectite textures are noted in high-Fe phases. All elements except Br are significantly enriched in the fly ash relative to the coal, which contains 35% ash. Particle chemistry is consistent with the major mineral phases identified by XRD, which include: quartz, magnetite, mullite, gehlenite, anorthite, hematite, anhydrite, and clinopyroxene.« less

  5. FDTD modeling of solar energy absorption in silicon branched nanowires.

    PubMed

    Lundgren, Christin; Lopez, Rene; Redwing, Joan; Melde, Kathleen

    2013-05-06

    Thin film nanostructured photovoltaic cells are increasing in efficiency and decreasing the cost of solar energy. FDTD modeling of branched nanowire 'forests' are shown to have improved optical absorption in the visible and near-IR spectra over nanowire arrays alone, with a factor of 5 enhancement available at 1000 nm. Alternate BNW tree configurations are presented, achieving a maximum absorption of over 95% at 500 nm.

  6. Absorption Efficiencies of Forsterite. I: DDA Explorations in Grain Shape and Size

    NASA Technical Reports Server (NTRS)

    Lindsay, Sean S.; Wooden, Diane; Harker, David E.; Kelley, Michael S.; Woodward, Charles E.; Murphy, Jim R.

    2013-01-01

    We compute the absorption efficiency (Q(sub abs)) of forsterite using the discrete dipole approximation (DDA) in order to identify and describe what characteristics of crystal grain shape and size are important to the shape, peak location, and relative strength of spectral features in the 8 - 40 micron wavelength range. Using the DDSCAT code, we compute Q(sub abs) for non-spherical polyhedral grain shapes with a(sub eff) = 0.1 micron. The shape characteristics identified are: 1) elongation/reduction along one of three crystallographic axes; 2) asymmetry, such that all three crystallographic axes are of different lengths; and 3) the presence of crystalline faces that are not parallel to a specific crystallographic axis, e.g., non-rectangular prisms and (di)pyramids. Elongation/reduction dominates the locations and shapes of spectral features near 10, 11, 16, 23.5, 27, and 33.5 micron, while asymmetry and tips are secondary shape effects. Increasing grain sizes (0.1 - 1.0 micron) shifts the 10, 11 micron features systematically towards longer wavelengths and relative to the 11 micron feature increases the strengths and slightly broadens the longer wavelength features. Seven spectral shape classes are established for crystallographic a-, b-, and c-axes and include columnar and platelet shapes plus non-elongated or equant grain shapes. The spectral shape classes and the effects of grain size have practical application in identifying or excluding columnar, platelet or equant forsterite grain shapes in astrophysical environs. Identification of the shape characteristics of forsterite from 8 - 40 micron spectra provides a potential means to probe the temperatures at which forsterite formed.

  7. Approaching perfect absorption of monolayer molybdenum disulfide at visible wavelengths using critical coupling.

    PubMed

    Jiang, Xiaoyun; Wang, Tao; Xiao, Shuyuan; Yan, Xicheng; Cheng, Le; Zhong, Qingfang

    2018-08-17

    A simple perfect absorption structure is proposed to achieve the high efficiency light absorption of monolayer molybdenum disulfide (MoS 2 ) by the critical coupling mechanism of guided resonances. The results of numerical simulation and theoretical analysis show that the light absorption in this atomically thin layer can be as high as 98.3% at the visible wavelengths, which is over 12 times more than that of a bare monolayer MoS 2 . In addition, the operating wavelength can be tuned flexibly by adjusting the radius of the air hole and the thickness of the dielectric layers, which is of great practical significance to improve the efficiency and selectivity of the absorption in monolayer MoS 2 . The novel idea of using critical coupling to enhance the light-MoS 2 interaction can be also adopted in other atomically thin materials. The meaningful improvement and tunability of the absorption in monolayer MoS 2 provides a good prospect for the realization of high-performance MoS 2 -based optoelectronic applications, such as photodetection and photoluminescence.

  8. Sound absorption of a new oblique-section acoustic metamaterial with nested resonator

    NASA Astrophysics Data System (ADS)

    Gao, Nansha; Hou, Hong; Zhang, Yanni; Wu, Jiu Hui

    2018-02-01

    This study designs and investigates high-efficiency sound absorption of new oblique-section nested resonators. Impedance tube experiment results show that different combinations of oblique-section nest resonators have tunable low-frequency bandwidth characteristics. The sound absorption mechanism is due to air friction losses in the slotted region and the sample structure resonance. The acousto-electric analogy model demonstrates that the sound absorption peak and bandwidth can be modulated over an even wider frequency range by changing the geometric size and combinations of structures. The proposed structure can be easily fabricated and used in low-frequency sound absorption applications.

  9. Brownian rotational relaxation and power absorption in magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Goya, G. F.; Fernandez-Pacheco, R.; Arruebo, M.; Cassinelli, N.; Ibarra, M. R.

    2007-09-01

    We present a study of the power absorption efficiency in several magnetite-based colloids, to asses their potential as magnetic inductive hyperthermia (MIH) agents. Relaxation times τ were measured through the imaginary susceptibility component χ″(T), and analyzed within Debye's theory of dipolar fluid. The results indicated Brownian rotational relaxation and allowed to calculate the hydrodynamic radius close to the values obtained from photon correlation. The study of the colloid performances as power absorbers showed no detectable increase of temperature for dextran-coated Fe 3O 4 nanoparticles, whereas a second Fe 3O 4-based dispersion of similar concentration could be heated up to 12 K after 30 min under similar experimental conditions. The different power absorption efficiencies are discussed in terms of the magnetic structure of the nanoparticles.

  10. Superior plasmon absorption in iron-doped gold nanoparticles.

    PubMed

    Amendola, Vincenzo; Saija, Rosalba; Maragò, Onofrio M; Iatì, Maria Antonia

    2015-05-21

    Although the excitation of localized surface plasmons is associated with enhanced scattering and absorption of incoming photons, only the latter is relevant for the efficient conversion of light into heat. Here we show that the absorption cross section of gold nanoparticles is sensibly increased when iron is included in the lattice as a substitutional dopant, i.e. in a gold-iron nanoalloy. Such an increase is size and shape dependent, with the best performance observed in nanoshells where a 90-190% improvement is found in a size range that is crucial for practical applications. Our findings are unexpected according to the common belief and previous experimental observations that alloys of Au with transition metals show a depressed plasmonic response. These results are promising for the design of efficient plasmonic converters of light into heat and pave the way to more in-depth investigations of the plasmonic properties in noble metal nanoalloys.

  11. Resonantly enhanced multiple exciton generation through below-band-gap multi-photon absorption in perovskite nanocrystals.

    PubMed

    Manzi, Aurora; Tong, Yu; Feucht, Julius; Yao, En-Ping; Polavarapu, Lakshminarayana; Urban, Alexander S; Feldmann, Jochen

    2018-04-17

    Multi-photon absorption and multiple exciton generation represent two separate strategies for enhancing the conversion efficiency of light into usable electric power. Targeting below-band-gap and above-band-gap energies, respectively, to date these processes have only been demonstrated independently. Here we report the combined interaction of both nonlinear processes in CsPbBr 3 perovskite nanocrystals. We demonstrate nonlinear absorption over a wide range of below-band-gap excitation energies (0.5-0.8 E g ). Interestingly, we discover high-order absorption processes, deviating from the typical two-photon absorption, at specific energetic positions. These energies are associated with a strong enhancement of the photoluminescence intensity by up to 10 5 . The analysis of the corresponding energy levels reveals that the observed phenomena can be ascribed to the resonant creation of multiple excitons via the absorption of multiple below-band-gap photons. This effect may open new pathways for the efficient conversion of optical energy, potentially also in other semiconducting materials.

  12. 4-channels coherent perfect absorption (CPA)-type demultiplexer using plasmonic nano spheres

    NASA Astrophysics Data System (ADS)

    Soltani, Mohamadreza; Keshavarzi, Rasul

    2017-10-01

    The current research represents a nanoscale and compact 4-channels plasmonic demultiplexer. It includes eight coherent perfect absorption (CPA) - type filters. The operation principle is based on the absorbable formation of a conductive path in the dielectric layer of a plasmonic nano-spheres waveguide. Since the CPA efficiency depends strongly on the number of plasmonic nano-spheres and the nano spheres location, an efficient binary optimization method based on the Particle Swarm Optimization algorithm is used to design an optimized array of the plasmonic nano-sphere in order to achieve the maximum absorption coefficient in the 'off' state.

  13. 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

  14. 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.

  15. Hearing on the Reauthorization of the Higher Education Act of 1965; Sallie Mae--Safety and Soundness. Hearing before the Subcommittee on Postsecondary Education of the Committee on Education and Labor. House of Representatives, One Hundred Second Congress, First Session.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. House Subcommittee on Postsecondary Education.

    As part of a series of hearings on the reauthorization of the Higher Education Act of 1965, testimony was heard on the safety and soundness of the Student Loan Marketing Association (Sallie Mae). Witnesses discussed many issues surrounding financial oversight of federal agencies and financial risk to the taxpayer through the potential failure of…

  16. [Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

    PubMed

    Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng

    2008-07-01

    A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

  17. Conical structures for highly efficient solar cell applications

    NASA Astrophysics Data System (ADS)

    Korany, Fatma M. H.; Hameed, Mohamed Farhat O.; Hussein, Mohamed; Mubarak, Roaa; Eladawy, Mohamed I.; Obayya, Salah Sabry A.

    2018-01-01

    Improving solar cell efficiency is a critical research topic. Nowadays, light trapping techniques are a promising way to enhance solar cell performance. A modified nanocone nanowire (NW) is proposed and analyzed for solar cell applications. The suggested NW consists of conical and truncated conical units. The geometrical parameters are studied using a three-dimensional (3-D) finite difference time-domain (FDTD) method to achieve broadband absorption through the reported design and maximize its ultimate efficiency. The analyzed parameters are absorption spectra, ultimate efficiency, and short circuit current density. The numerical results prove that the proposed structure is superior compared with cone, truncated cone, and cylindrical NWs. The reported design achieves an ultimate efficiency of 44.21% with substrate and back reflector. Further, short circuit current density of 36.17 mA / cm2 is achieved by the suggested NW. The electrical performance analysis of the proposed structure including doping concentration, junction thickness, and Shockley-Read-Hall recombination is also investigated. The electrical simulations show that a power conversion efficiency of 17.21% can be achieved using the proposed NW. The modified nanocone has advantages of broadband absorption enhancement, low cost, and fabrication feasibility.

  18. Validation of green-solvent extraction combined with chromatographic chemical fingerprint to evaluate quality of Stevia rebaudiana Bertoni.

    PubMed

    Teo, Chin Chye; Tan, Swee Ngin; Yong, Jean Wan Hong; Hew, Choy Sin; Ong, Eng Shi

    2009-02-01

    An approach that combined green-solvent methods of extraction with chromatographic chemical fingerprint and pattern recognition tools such as principal component analysis (PCA) was used to evaluate the quality of medicinal plants. Pressurized hot water extraction (PHWE) and microwave-assisted extraction (MAE) were used and their extraction efficiencies to extract two bioactive compounds, namely stevioside (SV) and rebaudioside A (RA), from Stevia rebaudiana Bertoni (SB) under different cultivation conditions were compared. The proposed methods showed that SV and RA could be extracted from SB using pure water under optimized conditions. The extraction efficiency of the methods was observed to be higher or comparable to heating under reflux with water. The method precision (RSD, n = 6) was found to vary from 1.91 to 2.86% for the two different methods on different days. Compared to PHWE, MAE has higher extraction efficiency with shorter extraction time. MAE was also found to extract more chemical constituents and provide distinctive chemical fingerprints for quality control purposes. Thus, a combination of MAE with chromatographic chemical fingerprints and PCA provided a simple and rapid approach for the comparison and classification of medicinal plants from different growth conditions. Hence, the current work highlighted the importance of extraction method in chemical fingerprinting for the classification of medicinal plants from different cultivation conditions with the aid of pattern recognition tools used.

  19. One-step fabrication of N-doped CNTs encapsulating M nanoparticles (M = Fe, Co, Ni) for efficient microwave absorption

    NASA Astrophysics Data System (ADS)

    Ning, Mingqiang; Li, Jingbo; Kuang, Boya; Wang, Chengzhi; Su, Dezhi; Zhao, Yongjie; Jin, Haibo; Cao, Maosheng

    2018-07-01

    By using a modified non-toxic pyrolysis method, M@NCNTs comprising in-situ formed M nanoparticles encapsulated in nitrogen-doped carbon nanotubes (NCNTs) have been synthesized. Compared to traditional preparation process of M@CNTs (eg: acid-aid treatment to CNTs then decorating M particles onto), this method holds the advantage of free of complicated treatment processes. The M@NCNTs exhibit tightly connected interfaces of M/NCNTs and contain abundant N dopants, which could contribute interfacial polarization and defect-dipole polarization to improving the microwave absorption performance. An intense dielectric relaxation is observed in Fe@NCNTs samples, which further enhances the dielectric loss. As expected, the as-synthesized M@NCNTs composites demonstrate promising candidates in microwave absorption (MWA) application. The minimum reflection loss (RL) of Fe@NCNTs (with 10 wt% loading) is up to -30.43 dB at 3.2 mm, and the effective absorption bandwidth (RL < -10 dB) is as wide as 5.7 GHz which benefits from the neighboring dual absorption peaks induced by the intense dielectric relaxation. Co@NCNTs and Ni@NCNTs also have satisfactory effective absorption bandwidth ∼4.08 and ∼4.72 GHz, respectively. The modified pyrolysis method is low-cost and non-toxic, which could become an industrial technique to synthesize carbonaceous composites for microwave absorption.

  20. Co-sensitization of natural dyes for improved efficiency in dye-sensitized solar cell application

    NASA Astrophysics Data System (ADS)

    Kumar, K. Ashok; Subalakshmi, K.; Senthilselvan, J.

    2016-05-01

    In this paper, a new approach of co-sensitized DSSC based on natural dyes is investigated to explore the possible way to improve the power conversion efficiency. To realize this purpose 10 DSSC devices were fabricated using mono-sensitization and co-sensitization of ethanolic extracts of natural dye sensitizers obtained from Cactus fruit, Jambolana fruit, Curcumin and Bermuda grass. The optical absorption spectrum of the mono and hybrid dye extracts were studied by UV-Visible absorption spectrum. It shows the characteristic absorption peaks in visible region corresponds to the presence of natural pigments of anthocyanin, betacyanin and chlorophylls. Absorption spectrum of hybrid dyes reveals a wide absorption band in visible region with improved extinction co-efficient and it is favorable for increased light harvesting nature. The power conversion efficiency of DSSC devices were calculated using J-V curve and the maximum efficiency achieved in the present work is noted to be ~0.61% for Cactus-Bermuda co-sensitized DSSC.

  1. Broadband ultrafast transient absorption of multiple exciton dynamics in lead sulfide nanocrystals

    NASA Astrophysics Data System (ADS)

    Gesuele, Felice; Wong, Chee Wei; Sfeir, Matthew; Misewich, James; Koh, Weonkyu; Murray, Christopher

    2011-03-01

    Multiple exciton generation (MEG) is under intense investigation as potential third-generation solar photovoltaics with efficiencies beyond the Shockley-Queisser limit. We examine PbS nanocrystals, dispersed and vigorously stirred in TCE solution, by means of supercontinuum femtosecond transient absorption (TA). TA spectra show the presence of first and second order bleaches for the 1Sh-Se and 1Ph-Pe excitonic transition while photoinduced absorption for the 1Sh,e-Ph,e transitions. We found evidence of carrier multiplication (MEG for single absorbed photon) from the analysis of the first and second order bleaches, in the limit of low number of absorbed photons (Nabs ~ 0.01), for energy three times and four times the Energy gap. The MEG efficiency, derived from the ratio between early-time to long-time TA signal, presents a strongly dispersive behavior with maximum red shifted respect the first absorption peak. Analysis of population dynamics shows that in presence of biexciton, the 1Sh-Se bleach peak is red-shifted indicating a positive binding energy. MEG efficiency estimation will be discussed with regards to spectral integration, correlated higher-order and first excitonic transitions, as well as the nanocrystal morphologies.

  2. Absorption heat pump for space applications

    NASA Technical Reports Server (NTRS)

    Nguyen, Tuan; Simon, William E.; Warrier, Gopinath R.; Woramontri, Woranun

    1993-01-01

    In the first part, the performance of the Absorption Heat Pump (AHP) with water-sulfuric acid and water-magnesium chloride as two new refrigerant-absorbent fluid pairs was investigated. A model was proposed for the analysis of the new working pairs in a heat pump system, subject to different temperature lifts. Computer codes were developed to calculate the Coefficient of Performance (COP) of the system with the thermodynamic properties of the working fluids obtained from the literature. The study shows the potential of water-sulfuric acid as a satisfactory replacement for water-lithium bromide in the targeted temperature range. The performance of the AHP using water-magnesium chloride as refrigerant-absorbent pair does not compare well with those obtained using water-lithium bromide. The second part concentrated on the design and testing of a simple ElectroHydrodynamic (EHD) Pump. A theoretical design model based on continuum electromechanics was analyzed to predict the performance characteristics of the EHD pump to circulate the fluid in the absorption heat pump. A numerical method of solving the governing equations was established to predict the velocity profile, pressure - flow rate relationship and efficiency of the pump. The predicted operational characteristics of the EHD pump is comparable to that of turbomachinery hardware; however, the overall efficiency of the electromagnetic pump is much lower. An experimental investigation to verify the numerical results was conducted. The pressure - flow rate performance characteristics and overall efficiency of the pump obtained experimentally agree well with the theoretical model.

  3. Exploring the origin of high optical absorption in conjugated polymers.

    PubMed

    Vezie, Michelle S; Few, Sheridan; Meager, Iain; Pieridou, Galatia; Dörling, Bernhard; Ashraf, Raja Shahid; Goñi, Alejandro R; Bronstein, Hugo; McCulloch, Iain; Hayes, Sophia C; Campoy-Quiles, Mariano; Nelson, Jenny

    2016-07-01

    The specific optical absorption of an organic semiconductor is critical to the performance of organic optoelectronic devices. For example, higher light-harvesting efficiency can lead to higher photocurrent in solar cells that are limited by sub-optimal electrical transport. Here, we compare over 40 conjugated polymers, and find that many different chemical structures share an apparent maximum in their extinction coefficients. However, a diketopyrrolopyrrole-thienothiophene copolymer shows remarkably high optical absorption at relatively low photon energies. By investigating its backbone structure and conformation with measurements and quantum chemical calculations, we find that the high optical absorption can be explained by the high persistence length of the polymer. Accordingly, we demonstrate high absorption in other polymers with high theoretical persistence length. Visible light harvesting may be enhanced in other conjugated polymers through judicious design of the structure.

  4. Energy-Looping Nanoparticles: Harnessing Excited-State Absorption for Deep-Tissue Imaging.

    PubMed

    Levy, Elizabeth S; Tajon, Cheryl A; Bischof, Thomas S; Iafrati, Jillian; Fernandez-Bravo, Angel; Garfield, David J; Chamanzar, Maysamreza; Maharbiz, Michel M; Sohal, Vikaas S; Schuck, P James; Cohen, Bruce E; Chan, Emory M

    2016-09-27

    Near infrared (NIR) microscopy enables noninvasive imaging in tissue, particularly in the NIR-II spectral range (1000-1400 nm) where attenuation due to tissue scattering and absorption is minimized. Lanthanide-doped upconverting nanocrystals are promising deep-tissue imaging probes due to their photostable emission in the visible and NIR, but these materials are not efficiently excited at NIR-II wavelengths due to the dearth of lanthanide ground-state absorption transitions in this window. Here, we develop a class of lanthanide-doped imaging probes that harness an energy-looping mechanism that facilitates excitation at NIR-II wavelengths, such as 1064 nm, that are resonant with excited-state absorption transitions but not ground-state absorption. Using computational methods and combinatorial screening, we have identified Tm(3+)-doped NaYF4 nanoparticles as efficient looping systems that emit at 800 nm under continuous-wave excitation at 1064 nm. Using this benign excitation with standard confocal microscopy, energy-looping nanoparticles (ELNPs) are imaged in cultured mammalian cells and through brain tissue without autofluorescence. The 1 mm imaging depths and 2 μm feature sizes are comparable to those demonstrated by state-of-the-art multiphoton techniques, illustrating that ELNPs are a promising class of NIR probes for high-fidelity visualization in cells and tissue.

  5. Optimizing the ionization and energy absorption of laser-irradiated clusters

    NASA Astrophysics Data System (ADS)

    Kundu, M.; Bauer, D.

    2008-03-01

    It is known that rare-gas or metal clusters absorb incident laser energy very efficiently. However, due to the intricate dependencies on all the laser and cluster parameters, it is difficult to predict under which circumstances ionization and energy absorption are optimal. With the help of three-dimensional particle-in-cell simulations of xenon clusters (up to 17256 atoms), it is shown that for a given laser pulse energy and cluster, an optimum wavelength exists that corresponds to the approximate wavelength of the transient, linear Mie-resonance of the ionizing cluster at an early stage of negligible expansion. In a single ultrashort laser pulse, the linear resonance at this optimum wavelength yields much higher absorption efficiency than in the conventional, dual-pulse pump-probe setup of linear resonance during cluster expansion.

  6. MULTIMAGNON ABSORPTION IN MNF2-OPTICAL ABSORPTION SPECTRUM.

    DTIC Science & Technology

    The absorption spectrum of MnF2 at 4.2K in the 3900A region was measured in zero external fields and in high fields. Exciton lines with magnon ...sidebands are observed, accompanied by a large number of weak satellite lines. Results on the exciton and magnon absorptions are similar to those of...McClure et al. The satellite lines are interpreted as being multi- magnon absorptions, and it is possible to fit the energy of all the absorptions with

  7. A new method for microwave assisted ethanolic extraction of Mentha rotundifolia bioactive terpenoids.

    PubMed

    García-Sarrió, María Jesús; Sanz, María Luz; Sanz, Jesús; González-Coloma, Azucena; Cristina Soria, Ana

    2018-04-14

    A new microwave-assisted extraction (MAE) method using ethanol as solvent has been optimized by means of a Box-Behnken experimental design for the enhanced extraction of bioactive terpenoids from Mentha rotundifolia leaves; 100°C, 5 min, 1.125 g dry sample: 10 mL solvent and a single extraction cycle were selected as optimal conditions. Improved performance of MAE method in terms of extraction yield and/or reproducibility over conventional solid-liquid extraction and ultrasound assisted extraction was also previously assessed. A comprehensive characterization of MAE extracts was carried out by GC-MS. A total of 46 compounds, mostly terpenoids, were identified; piperitenone oxide and piperitenone were the major compounds determined. Several neophytadiene isomers were also detected for the first time in MAE extracts. Different procedures (solid-phase extraction and activated charcoal (AC) treatment) were also evaluated for clean-up of MAE extracts, with AC providing the highest enrichment in bioactive terpenoids. Finally, the MAE method here developed is shown as a green, fast, efficient and reproducible liquid extraction methodology to obtain M. rotundifolia bioactive extracts for further application, among others, as food preservatives. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Energy and Exergy Analysis of Vapour Absorption Refrigeration Cycle—A Review

    NASA Astrophysics Data System (ADS)

    Kanabar, Bhaveshkumar Kantilal; Ramani, Bharatkumar Maganbhai

    2016-07-01

    In recent years, an energy crisis and the energy consumption have become global problems which restrict the sustainable growth. In these scenarios the scientific energy recovery and the utilization of various kinds of waste heat become very important. The waste heat can be utilized in many ways and one of the best practices is to use it for vapour absorption refrigeration system. To ensure efficient working of absorption cycle and utilization of optimum heat, exergy is the best tool for analysis. This paper provides the comprehensive picture of research and development of absorption refrigeration technology, practical and theoretical analysis with different arrangements of the cycle.

  9. Qubit absorption refrigerator at strong coupling

    NASA Astrophysics Data System (ADS)

    Mu, Anqi; Agarwalla, Bijay Kumar; Schaller, Gernot; Segal, Dvira

    2017-12-01

    We demonstrate that a quantum absorption refrigerator (QAR) can be realized from the smallest quantum system, a qubit, by coupling it in a non-additive (strong) manner to three heat baths. This function is un-attainable for the qubit model under the weak system-bath coupling limit, when the dissipation is additive. In an optimal design, the reservoirs are engineered and characterized by a single frequency component. We then obtain closed expressions for the cooling window and refrigeration efficiency, as well as bounds for the maximal cooling efficiency and the efficiency at maximal power. Our results agree with macroscopic designs and with three-level models for QARs, which are based on the weak system-bath coupling assumption. Beyond the optimal limit, we show with analytical calculations and numerical simulations that the cooling efficiency varies in a non-universal manner with model parameters. Our work demonstrates that strongly-coupled quantum machines can exhibit function that is un-attainable under the weak system-bath coupling assumption.

  10. 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.

  11. Optical absorption enhancement in silicon nanowire arrays with a large lattice constant for photovoltaic applications.

    PubMed

    Lin, Chenxi; Povinelli, Michelle L

    2009-10-26

    In this paper, we use the transfer matrix method to calculate the optical absorptance of vertically-aligned silicon nanowire (SiNW) arrays. For fixed filling ratio, significant optical absorption enhancement occurs when the lattice constant is increased from 100 nm to 600 nm. The enhancement arises from an increase in field concentration within the nanowire as well as excitation of guided resonance modes. We quantify the absorption enhancement in terms of ultimate efficiency. Results show that an optimized SiNW array with lattice constant of 600 nm and wire diameter of 540 nm has a 72.4% higher ultimate efficiency than a Si thin film of equal thickness. The enhancement effect can be maintained over a large range of incidence angles.

  12. Enhancement of optical absorption of Si (100) surfaces by low energy N+ ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Bhowmik, Dipak; Karmakar, Prasanta

    2018-05-01

    The increase of optical absorption efficiency of Si (100) surface by 7 keV and 8 keV N+ ions bombardment has been reported here. A periodic ripple pattern on surface has been observed as well as silicon nitride is formed at the ion impact zones by these low energy N+ ion bombardment [P. Karmakar et al., J. Appl. Phys. 120, 025301 (2016)]. The light absorption efficiency increases due to the presence of silicon nitride compound as well as surface nanopatterns. The Atomic Force Microscopy (AFM) study shows the formation of periodic ripple pattern and increase of surface roughness with N+ ion energy. The enhancement of optical absorption by the ion bombarded Si, compared to the bare Si have been measured by UV - visible spectrophotometer.

  13. Exciplex formation and electroluminescent absorption in ultraviolet organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Zhang, Qi; Zhang, Hao; Zhang, Xiao-Wen; Xu, Tao; Wei, Bin

    2015-02-01

    We investigated the formation of exciplex and electroluminescent absorption in ultraviolet organic light-emitting diodes (UV OLEDs) using different heterojunction structures. It is found that an energy barrier of over 0.3 eV between the emissive layer (EML) and adjacent transport layer facilitates exciplex formation. The electron blocking layer effectively confines electrons in the EML, which contributes to pure UV emission and enhances efficiency. The change in EML thickness generates tunable UV emission from 376 nm to 406 nm. In addition, the UV emission excites low-energy organic function layers and produces photoluminescent emission. In UV OLED, avoiding the exciplex formation and averting light absorption can effectively improve the purity and efficiency. A maximum external quantum efficiency of 1.2% with a UV emission peak of 376 nm is realized. Project supported by the National Natural Science Foundation of China (Grant Nos. 61136003 and 61275041) and the Guangxi Provincial Natural Science Foundation, China (Grant No. 2012GXNSFBA053168).

  14. European Regional Climate Zone Modeling of a Commercial Absorption Heat Pump Hot Water Heater

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

    Sharma, Vishaldeep; Shen, Bo; Keinath, Chris

    2017-01-01

    High efficiency gas-burning hot water heating takes advantage of a condensing heat exchanger to deliver improved combustion efficiency over a standard non-condensing configuration. The water heating is always lower than the gas heating value. In contrast, Gas Absorption Heat Pump (GAHP) hot water heating combines the efficiency of gas burning with the performance increase from a heat pump to offer significant gas energy savings. An ammonia-water system also has the advantage of zero Ozone Depletion Potential and low Global Warming Potential. In comparison with air source electric heat pumps, the absorption system can maintain higher coefficients of performance in coldermore » climates. In this work, a GAHP commercial water heating system was compared to a condensing gas storage system for a range of locations and climate zones across Europe. The thermodynamic performance map of a single effect ammonia-water absorption system was used in a building energy modeling software that could also incorporate the changing ambient air temperature and water mains temperature for a specific location, as well as a full-service restaurant water draw pattern.« less

  15. Efficacy, safety and mechanism of HP-β-CD-PEI polymers as absorption enhancers on the intestinal absorption of poorly absorbable drugs in rats.

    PubMed

    Zhang, Hailong; Huang, Xiaoyan; Zhang, Yongjing; Gao, Yang

    2017-03-01

    Oral bioavailability of some hydrophilic therapeutic macromolecules was very poor, thus leading to their limited application in clinic. To investigate the efficacy, safety and mechanism of HP-β-CD-PEI polymers on the intestinal absorption of some poorly absorbable drugs in rats. Effects of HP-β-CD-PEI polymers on the intestinal absorptions of drugs were investigated by an in situ closed loop method in rats. The safety of HP-β-CD-PEI polymer was evaluated by measurement of lactate dehydrogenase (LDH) activity and amount of protein released from rat intestinal perfusate. The absorption enhancing mechanisms were explored by the measurement of zeta potential, transepithelial electrical resistance (TEER) and in vitro transport of FD4 (a paracellular marker) across rat intestinal membranes, respectively. HP-β-CD-PEI polymers, especially HP-β-CD-PEI 1800 , demonstrated excellent absorption enhancing effects on drug absorption in a concentration-dependent manner and the enhancing effect was more efficient in the small intestine than that in the large intestine. Five percent (w/v) HP-β-CD-PEI 1800 obviously decreased the TEER, accompanied with increase in the intestinal transport of FD4, indicating that absorption enhancing actions of HP-β-CD-PEI polymers were possibly performed by loosening tight junctions of intestinal epithelium cells, thereby increasing drug permeation via a paracellular pathway. A good liner relationship between absorption enhancing effects of HP-β-CD-PEI polymers and their zeta potentials suggested the contribution of positive charge on the surface of these polymers to their absorption enhancing effects. HP-β-CD-PEI polymers might be potential and safe absorption enhancers for improving oral delivery of poorly absorbable macromolecules including peptides and proteins.

  16. Optimized microwave-assisted extraction of 6-gingerol from Zingiber officinale Roscoeand evaluation of antioxidant activity in vitro.

    PubMed

    Liu, Wei; Zhou, Chun-Li; Zhao, Jing; Chen, Dong; Li, Quan-Hong

    2014-01-01

    6-Gingerol is one of the most pharmacologically active and abundant components in ginger, which has a wide array of biochemical and pharmacologic activities. In recent years, the application of microwave-assisted extraction (MAE) for obtaining bioactive compounds from plant materials has shown tremendous research interest and potential. In this study, an efficient microwave-assisted extraction (MAE) technique was developed to extract 6-gingerol from ginger. The extraction efficiency of MAE was also compared with conventional extraction techniques. Fresh gingers (Zingiber officinale Rose.) were harvested at commercial maturity (originally from Shandong, laiwu, China). In single-factor experiments for the recovery of 6-gingerol, proper ranges of ratio of liquid to solid, ethanol proportion, microwave power, extraction time were determined. Based on the values obtained in single-factor experiments, a Box-Behnken design (BBD) was applied to determine the best combination of extraction variables on the yield of 6-gingerol. The optimum extraction conditions were as follows: microwave power 528 W, ratio of liquid to solid 26 mL·g(-1), extraction time 31 s and ethanol proportion 78%. Furthermore, more 6-gingerol and total polyphenols contents were extracted by MAE than conventional methods including Maceration (MAC), Stirring Extraction (SE), Heat reflux extraction (HRE), Ultrasound-assisted extraction (UAE), as well as the antioxidant capacity. Microwave-assisted extraction showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. Scanning electron microscopy (SEM) images of ginger powder materials after different extractions were obtained to provide visual evidence of the disruption effect. To our best knowledge, this is the first report about usage of MAE of 6-gingerol extraction from ginger, which could be referenced for the extraction of other active compounds from herbal plants.

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

    PubMed

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

    2014-02-01

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

  18. New insights into the molecular mechanism of intestinal fatty acid absorption

    PubMed Central

    Wang, Tony Y.; Liu, Min; Portincasa, Piero; Wang, David Q.-H.

    2013-01-01

    Background Dietary fat is the most important energy source of all the nutrients. Fatty acids, stored as triacylglycerols in the body, are an important reservoir of stored energy and derive primarily from animal fats and vegetable oils. Design Although the molecular mechanisms for the transport of water-insoluble amphipathic fatty acids across cell membranes have been debated for many years, it is now believed that the dominant means for intestinal fatty acid uptake is via membrane-associated fatty acid-binding proteins, i.e., fatty acid transporters on the apical membrane of enterocytes. Results These findings indicate that intestinal fatty acid absorption is a multistep process that is regulated by multiple genes at the enterocyte level, and intestinal fatty acid absorption efficiency could be determined by factors influencing intraluminal fatty acid molecules across the brush border membrane of enterocytes. To facilitate research on intestinal, hepatic and plasma triacylglycerol metabolism, it is imperative to establish standard protocols for precisely and accurately measuring the efficiency of intestinal fatty acid absorption in humans and animal models. In this review, we will discuss the chemical structure and nomenclature of fatty acids and summarize recent progress in investigating the molecular mechanisms underlying the intestinal absorption of fatty acids, with a particular emphasis on the physical-chemistry of intestinal lipids and the molecular physiology of intestinal fatty acid transporters. Conclusions A better understanding of the molecular mechanism of intestinal fatty acid absorption should lead to novel approaches to the treatment and the prevention of fatty acid-related metabolic diseases that are prevalent worldwide. PMID:24102389

  19. Beyond Yellow Curry: Assessing Commercial Curcumin Absorption Technologies

    PubMed Central

    Douglass, Brad J.; Clouatre, Dallas L.

    2015-01-01

    BACKGROUND: Few natural products have demonstrated the range of protective and therapeutic promise as have turmeric and its principal bioactive components: curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Success in translating this potential into tangible benefits has been limited by inherently poor intestinal absorption, rapid metabolism, and limited systemic bioavailability. Seeking to overcome these limitations, food ingredient formulators have begun to employ a variety of approaches to enhance absorption and bioactivity. Many of these strategies improve upon the age-old practice of consuming turmeric in fat-based sauces, such as in a fat-rich yellow curry. However, there exists uncertainty as to how the various commercially available offerings compare to each other in terms of either uptake or efficacy, and this uncertainty leaves physicians and nutritionists with a dearth of data for making recommendations to interested patients and consumers. Further complicating the issue are recent data suggesting that formulation strategies may not equally enhance the absorption of individual curcuminoids, a significant issue in that these curcuminoids exhibit somewhat different physiologic properties. OBJECTIVE: This review introduces needed order to the curcumin marketplace by examining bioavailability studies on a number of commercial curcumin ingredients and evaluating them on a level playing field. METHODS: The comparative analysis includes standard pharmacokinetic parameters and a new metric, relative mass efficiency (E). Relative mass efficiency allows for the comparison of different formulations even in cases in which the weight percentage of curcuminoids is vastly different. RESULTS: A hydrophilic carrier dispersed curcuminoid formula exhibits 45.9 times the bioavailability of the standard purified 95 percent curcuminoid preparation and, based on relative mass efficiency, 1.5 times the bioavailability of the next best commercial ingredient, a cyclodextrin

  20. Beyond Yellow Curry: Assessing Commercial Curcumin Absorption Technologies.

    PubMed

    Douglass, Brad J; Clouatre, Dallas L

    2015-01-01

    Few natural products have demonstrated the range of protective and therapeutic promise as have turmeric and its principal bioactive components: curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Success in translating this potential into tangible benefits has been limited by inherently poor intestinal absorption, rapid metabolism, and limited systemic bioavailability. Seeking to overcome these limitations, food ingredient formulators have begun to employ a variety of approaches to enhance absorption and bioactivity. Many of these strategies improve upon the age-old practice of consuming turmeric in fat-based sauces, such as in a fat-rich yellow curry. However, there exists uncertainty as to how the various commercially available offerings compare to each other in terms of either uptake or efficacy, and this uncertainty leaves physicians and nutritionists with a dearth of data for making recommendations to interested patients and consumers. Further complicating the issue are recent data suggesting that formulation strategies may not equally enhance the absorption of individual curcuminoids, a significant issue in that these curcuminoids exhibit somewhat different physiologic properties. This review introduces needed order to the curcumin marketplace by examining bioavailability studies on a number of commercial curcumin ingredients and evaluating them on a level playing field. The comparative analysis includes standard pharmacokinetic parameters and a new metric, relative mass efficiency (E). Relative mass efficiency allows for the comparison of different formulations even in cases in which the weight percentage of curcuminoids is vastly different. A hydrophilic carrier dispersed curcuminoid formula exhibits 45.9 times the bioavailability of the standard purified 95 percent curcuminoid preparation and, based on relative mass efficiency, 1.5 times the bioavailability of the next best commercial ingredient, a cyclodextrin complex. Delivery strategies can

  1. A Group Increment Scheme for Infrared Absorption Intensities of Greenhouse Gases

    NASA Technical Reports Server (NTRS)

    Kokkila, Sara I.; Bera, Partha P.; Francisco, Joseph S.; Lee, Timothy J.

    2012-01-01

    A molecule's absorption in the atmospheric infrared (IR) window (IRW) is an indicator of its efficiency as a greenhouse gas. A model for estimating the absorption of a fluorinated molecule within the IRW was developed to assess its radiative impact. This model will be useful in comparing different hydrofluorocarbons and hydrofluoroethers contribution to global warming. The absorption of radiation by greenhouse gases, in particular hydrofluoroethers and hydrofluorocarbons, was investigated using ab initio quantum mechanical methods. Least squares regression techniques were used to create a model based on this data. The placement and number of fluorines in the molecule were found to affect the absorption in the IR window and were incorporated into the model. Several group increment models are discussed. An additive model based on one-carbon groups is found to work satisfactorily in predicting the ab initio calculated vibrational intensities.

  2. Microwave-assisted extraction of coumarin and related compounds from Melilotus officinalis (L.) Pallas as an alternative to Soxhlet and ultrasound-assisted extraction.

    PubMed

    Martino, Emanuela; Ramaiola, Ilaria; Urbano, Mariangela; Bracco, Francesco; Collina, Simona

    2006-09-01

    Soxhlet extraction, ultrasound-assisted extraction (USAE) and microwaves-assisted extraction (MAE) in closed system have been investigated to determine the content of coumarin, o-coumaric and melilotic acids in flowering tops of Melilotus officinalis. The extracts were analyzed with an appropriate HPLC procedure. The reproducibility of extraction and of chromatographic analysis was proved. Taking into account the extraction yield, the cost and the time, we studied the effects of extraction variables on the yield of the above-mentioned compounds. Better results were obtained with MAE (50% v/v aqueous ethanol, two heating cycles of 5 min, 50 degrees C). On the basis of the ratio extraction yield/extraction time, we therefore propose MAE as the most efficient method.

  3. Energy absorption capability and crashworthiness of composite material structures: A review

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

    Carruthers, J.J.; Kettle, A.P.; Robinson, A.M.

    1998-10-01

    The controlled brittle failure of thermosetting fiber-reinforced polymer composites can provide a very efficient energy absorption mechanism. Consequently, the use of these materials in crashworthy vehicle designs has been the subject of considerable interest. In this respect, their more widespread application has been limited by the complexity of their collapse behavior. This article reviews the current level of understanding i this field, including the correlations between failure mode and energy absorption, the principal material, geometric, and physical parameters relevant to crashworthy design and methods of predicting the energy absorption capability of polymer composites. Areas which require further investigation are identified.more » This review article contains 70 references.« less

  4. Probiotic Bacillus coagulans GBI-30, 6086 Improves Protein Absorption and Utilization.

    PubMed

    Jäger, Ralf; Purpura, Martin; Farmer, Sean; Cash, Howard A; Keller, David

    2017-12-01

    Probiotics offer numerous health benefits, including digestive and immune health. Improved digestive health is linked to a more efficient absorption of important nutrients from our diet. This review focused on the rationale of using the probiotic Bacillus coagulans GBI-30, 6086 to aid protein absorption and utilization. B. coagulans GBI-30, 6086 can withstand the acidic environment of the stomach to reach the intestine where it germinates. Once active in the small intestine after germination, it has been shown to aid the digestion of carbohydrates and proteins. Co-administration of B. coagulans GBI-30, 6086 with protein has been shown to increase protein absorption and to maximize the health benefits associated with protein supplementation.

  5. Vehicle effects on human stratum corneum absorption and skin penetration.

    PubMed

    Zhang, Alissa; Jung, Eui-Chang; Zhu, Hanjiang; Zou, Ying; Hui, Xiaoying; Maibach, Howard

    2017-05-01

    This study evaluated the effects of three vehicles-ethanol (EtOH), isopropyl alcohol (IPA), and isopropyl myristate (IPM)-on stratum corneum (SC) absorption and diffusion of the [ 14 C]-model compounds benzoic acid and butenafine hydrochloride to better understand the transport pathways of chemicals passing through and resident in SC. Following application of topical formulations to human dermatomed skin for 30 min, penetration flux was observed for 24 h post dosing, using an in vitro flow-through skin diffusion system. Skin absorption and penetration was compared to the chemical-SC (intact, delipidized, or SC lipid film) binding levels. A significant vehicle effect was observed for chemical skin penetration and SC absorption. IPA resulted in the greatest levels of intact SC/SC lipid absorption, skin penetration, and total skin absorption/penetration of benzoic acid, followed by IPM and EtOH, respectively. For intact SC absorption and total skin absorption/penetration of butenafine, the vehicle that demonstrated the highest level of sorption/penetration was EtOH, followed by IPA and IPM, respectively. The percent doses of butenafine that were absorbed in SC lipid film and penetrated through skin in 24 h were greatest for IPA, followed by EtOH and IPM, respectively. The vehicle effect was consistent between intact SC absorption and total chemical skin absorption and penetration, as well as SC lipid absorption and chemical penetration through skin, suggesting intercellular transport as a main pathway of skin penetration for model chemicals. These results suggest the potential to predict vehicle effects on skin permeability with simple SC absorption assays. As decontamination was applied 30 min after chemical exposure, significant vehicle effects on chemical SC partitioning and percutaneous penetration also suggest that skin decontamination efficiency is vehicle dependent, and an effective decontamination method should act on chemical solutes in the lipid domain.

  6. Wearable slot antenna at 2.45 GHz for off-body radiation: Analysis of efficiency, frequency shift, and body absorption.

    PubMed

    Fernandez, Marta; Espinosa, Hugo G; Thiel, David V; Arrinda, Amaia

    2018-01-01

    The interaction of body-worn antennas with the human body causes a significant decrease in antenna efficiency and a shift in resonant frequency. A resonant slot in a small conductive box placed on the body has been shown to reduce these effects. The specific absorption rate is less than international health standards for most wearable antennas due to small transmitter power. This paper reports the linear relationship between power absorbed by biological tissues at different locations on the body and radiation efficiency based on numerical modeling (r = 0.99). While the -10 dB bandwidth of the antenna remained constant and equal to 12.5%, the maximum frequency shift occurred when the antenna was close to the elbow (6.61%) and on the thigh (5.86%). The smallest change was found on the torso (4.21%). Participants with body-mass index (BMI) between 17 and 29 kg/m 2 took part in experimental measurements, where the maximum frequency shift was 2.51%. Measurements showed better agreement with simulations on the upper arm. These experimental results demonstrate that the BMI for each individual had little effect on the performance of the antenna. Bioelectromagnetics. 39:25-34, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  7. Measurements of zinc absorption: application and interpretation in research designed to improve human zinc nutriture.

    PubMed

    Hambidge, K Michael; Miller, Leland V; Tran, Cuong D; Krebs, Nancy F

    2005-11-01

    The focus of this paper is on the application of measurements of zinc absorption in human research, especially studies designed to assess the efficacy of intervention strategies to prevent and manage zinc deficiency in populations. Emphasis is given to the measurement of quantities of zinc absorbed rather than restricting investigations to measurements of fractional absorption of zinc. This is especially important when determining absorption of zinc from the diet, whether it be the habitual diet or an intervention diet under evaluation. Moreover, measurements should encompass all meals for a minimum of one day with the exception of some pilot studies. Zinc absorption is primarily via an active saturable transport process into the enterocytes of the proximal small intestine. The relationship between quantity of zinc absorbed and the quantity ingested is best characterized by saturable binding models. When applied to human studies that have sufficient data to examine dose-response relationships, efficiency of absorption is high until approximately 50-60% maximal absorption is achieved, even with moderate phytate intakes. This also coincides approximately with the quantity of absorbed zinc necessary to meet physiologic requirements. Efficiency of absorption with intakes that exceed this level is low or very low. These observations have important practical implications for the design and interpretation of intervention studies to prevent zinc deficiency. They also suggest the potential utility of measurements of the quantity of zinc absorbed when evaluating the zinc status of populations.

  8. Emergency membrane contactor based absorption system for ammonia leaks in water treatment plants.

    PubMed

    Shao, Jiahui; Fang, Xuliang; He, Yiliang; Jin, Qiang

    2008-01-01

    Abstract Because of the suspected health risks of trihalomethanes (THMs), more and more water treatment plants have replaced traditional chlorine disinfection process with chloramines but often without the proper absorption system installed in the case of ammonia leaks in the storage room. A pilot plant membrane absorption system was developed and installed in a water treatment plant for this purpose. Experimentally determined contact angle, surface tension, and corrosion tests indicated that the sulfuric acid was the proper choice as the absorbent for leaking ammonia using polypropylene hollow fiber membrane contactor. Effects of several operating conditions on the mass transfer coefficient, ammonia absorption, and removal efficiency were examined, including the liquid concentration, liquid velocity, and feed gas concentration. Under the operation conditions investigated, the gas absorption efficiency over 99.9% was achieved. This indicated that the designed pilot plant membrane absorption system was effective to absorb the leaking ammonia in the model storage room. The removal rate of the ammonia in the model storage room was also experimentally and theoretically found to be primarily determined by the ammonia suction flow rate from the ammonia storage room to the membrane contactor. The ammonia removal rate of 99.9% was expected to be achieved within 1.3 h at the ammonia gas flow rate of 500 m3/h. The success of the pilot plant membrane absorption system developed in this study illustrated the potential of this technology for ammonia leaks in water treatment plant, also paved the way towards a larger scale application.

  9. Carbon Dioxide Absorption Heat Pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    2002-01-01

    A carbon dioxide absorption heat pump cycle is disclosed using a high pressure stage and a super-critical cooling stage to provide a non-toxic system. Using carbon dioxide gas as the working fluid in the system, the present invention desorbs the CO2 from an absorbent and cools the gas in the super-critical state to deliver heat thereby. The cooled CO2 gas is then expanded thereby providing cooling and is returned to an absorber for further cycling. Strategic use of heat exchangers can increase the efficiency and performance of the system.

  10. Modeling the Efficiency of a Germanium Detector

    NASA Astrophysics Data System (ADS)

    Hayton, Keith; Prewitt, Michelle; Quarles, C. A.

    2006-10-01

    We are using the Monte Carlo Program PENELOPE and the cylindrical geometry program PENCYL to develop a model of the detector efficiency of a planar Ge detector. The detector is used for x-ray measurements in an ongoing experiment to measure electron bremsstrahlung. While we are mainly interested in the efficiency up to 60 keV, the model ranges from 10.1 keV (below the Ge absorption edge at 11.1 keV) to 800 keV. Measurements of the detector efficiency have been made in a well-defined geometry with calibrated radioactive sources: Co-57, Se-75, Ba-133, Am-241 and Bi-207. The model is compared with the experimental measurements and is expected to provide a better interpolation formula for the detector efficiency than simply using x-ray absorption coefficients for the major constituents of the detector. Using PENELOPE, we will discuss several factors, such as Ge dead layer, surface ice layer and angular divergence of the source, that influence the efficiency of the detector.

  11. UV laser long-path absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf

    1994-01-01

    absorption measurements some specific problems of those detectors have to be solved experimentally (i.e. fixed pattern noise, dark signal noise, nonuniform efficiency of individual elements, spatial sensitivity variations). In order to improve the low spatial resolution we performed laboratory studies using a multiple reflection cell to convert the long path technique to a real in situ point measurement. Under the conditions of field experiments in Julich residual absorbance signals at present are about 1.5x10(exp -4) corresponding to an OH detection sensitivity of 2x10(exp 6) OH/cm(exp 3) using a light path of 5.8 km. Total integration times for one measurement point vary between a few minutes and an hour.

  12. QED-driven laser absorption

    NASA Astrophysics Data System (ADS)

    Levy, Matthew; Blackburn, T.; Ratan, N.; Sadler, J.; Ridgers, C.; Kasim, M.; Ceurvorst, L.; Holloway, J.; Baring, M.; Bell, A.; Glenzer, S.; Gregori, G.; Ilderton, A.; Marklund, M.; Tabak, M.; Wilks, S.; Norreys, P.

    2016-10-01

    Absorption covers the physical processes which convert intense photon flux into energetic particles when a high-power laser (I >1018 W cm-2 where I is intensity at 1 μm wavelength) illuminates optically-thick matter. It underpins important applications of petawatt laser systems today, e.g., in isochoric heating of materials. Next-generation lasers such as ELI are anticipated to produce quantum electrodynamical (QED) bursts of γ-rays and anti-matter via the multiphoton Breit-Wheeler process which could enable scaled laboratory probes, e.g., of black hole winds. Here, applying strong-field QED to advances in plasma kinematic theory, we present a model elucidating absorption limited only by an avalanche of self-created electron-positron pairs at ultra-high-field. The model, confirmed by multidimensional QED-PIC simulations, works over six orders of magnitude in optical intensity and reveals this cascade is initiated at 1.8 x 1025 W cm-2 using a realistic linearly-polarized laser pulse. Here the laser couples its energy into highly-collimated electrons, ions, γ-rays, and positrons at 12%, 6%, 58% and 13% efficiency, respectively. We remark on attributes of the QED plasma state and possible applications.

  13. Light absorption and excitation energy transfer calculations in primitive photosynthetic bacteria

    NASA Astrophysics Data System (ADS)

    Komatsu, Yu; Kayanuma, Megumi; Shoji, Mitsuo; Yabana, Kazuhiro; Shiraishi, Kenji; Umemura, Masayuki

    2015-06-01

    In photosynthetic organisms, light energy is converted into chemical energy through the light absorption and excitation energy transfer (EET) processes. These processes start in light-harvesting complexes, which contain special photosynthetic pigments. The exploration of unique mechanisms in light-harvesting complexes is directly related to studies, such as artificial photosynthesis or biosignatures in astrobiology. We examined, through ab initio calculations, the light absorption and EET processes using cluster models of light-harvesting complexes in purple bacteria (LH2). We evaluated absorption spectra and energy transfer rates using the LH2 monomer and dimer models to reproduce experimental results. After the calibration tests, a LH2 aggregation model, composed of 7 or 19 LH2s aligned in triangle lattice, was examined. We found that the light absorption is red shifted and the energy transfer becomes faster as the system size increases. We also found that EET is accelerated by exchanging the central pigments to lower energy excited pigments. As an astrobiological application, we calculated light absorptions efficiencies of the LH2 in different photoenvironments.

  14. Photoacoustic and filter measurements related to aerosol light absorption during the Northern Front Range Air Quality Study (Colorado 1996/1997)

    NASA Astrophysics Data System (ADS)

    Moosmüller, H.; Arnott, W. P.; Rogers, C. F.; Chow, J. C.; Frazier, C. A.; Sherman, L. E.; Dietrich, D. L.

    1998-11-01

    A new photoacoustic instrument for the measurement of aerosol light absorption was collocated with conventional aerosol instrumentation during the 1996-1997 winter intensive monitoring period of the Northern Front Range Air Quality Study. Measurements of the light absorption efficiency for black carbon were 5 m2/g at 685 nm and 10 m2/g at 532 nm, and for elemental carbon, they were 3.6 m2/g at 685 nm. We show that these values together with previous photoacoustic measurements of aerosol light absorption shed some light on the wavelength dependence of absorption efficiency for carbonaceous aerosol in the visible and near-visible region. Integrating plate type filter measurements of aerosol light absorption result in far larger values than those measured with the photoacoustic instrument. We demonstrate that a recently published correction technique [Horvath, 1997] can yield improved agreement.

  15. Multistage quantum absorption heat pumps.

    PubMed

    Correa, Luis A

    2014-04-01

    It is well known that heat pumps, while being all limited by the same basic thermodynamic laws, may find realization on systems as "small" and "quantum" as a three-level maser. In order to quantitatively assess how the performance of these devices scales with their size, we design generalized N-dimensional ideal heat pumps by merging N-2 elementary three-level stages. We set them to operate in the absorption chiller mode between given hot and cold baths and study their maximum achievable cooling power and the corresponding efficiency as a function of N. While the efficiency at maximum power is roughly size-independent, the power itself slightly increases with the dimension, quickly saturating to a constant. Thus, interestingly, scaling up autonomous quantum heat pumps does not render a significant enhancement beyond the optimal double-stage configuration.

  16. Characterization of Photon-Counting Detector Responsivity for Non-Linear Two-Photon Absorption Process

    NASA Technical Reports Server (NTRS)

    Sburlan, S. E.; Farr, W. H.

    2011-01-01

    Sub-band absorption at 1550 nm has been demonstrated and characterized on silicon Geiger mode detectors which normally would be expected to have no response at this wavelength. We compare responsivity measurements to singlephoton absorption for wavelengths slightly above the bandgap wavelength of silicon (approx. 1100 microns). One application for this low efficiency sub-band absorption is in deep space optical communication systems where it is desirable to track a 1030 nm uplink beacon on the same flight terminal detector array that monitors a 1550 nm downlink signal for pointingcontrol. The currently observed absorption at 1550 nm provides 60-70 dB of isolation compared to the response at 1064 nm, which is desirable to avoid saturation of the detector by scattered light from the downlink laser.

  17. New insights into the molecular mechanism of intestinal fatty acid absorption.

    PubMed

    Wang, Tony Y; Liu, Min; Portincasa, Piero; Wang, David Q-H

    2013-11-01

    Dietary fat is one of the most important energy sources of all the nutrients. Fatty acids, stored as triacylglycerols (also called triglycerides) in the body, are an important reservoir of stored energy and derived primarily from animal fats and vegetable oils. Although the molecular mechanisms for the transport of water-insoluble amphipathic fatty acids across cell membranes have been debated for many years, it is now believed that the dominant means for intestinal fatty acid uptake is via membrane-associated fatty acid-binding proteins, that is, fatty acid transporters on the apical membrane of enterocytes. These findings indicate that intestinal fatty acid absorption is a multistep process that is regulated by multiple genes at the enterocyte level, and intestinal fatty acid absorption efficiency could be determined by factors influencing intraluminal fatty acid molecules across the brush border membrane of enterocytes. To facilitate research on intestinal, hepatic and plasma triacylglycerol metabolism, it is imperative to establish standard protocols for precisely and accurately measuring the efficiency of intestinal fatty acid absorption in humans and animal models. In this review, we will discuss the chemical structure and nomenclature of fatty acids and summarize recent progress in investigating the molecular mechanisms underlying the intestinal absorption of fatty acids, with a particular emphasis on the physical chemistry of intestinal lipids and the molecular physiology of intestinal fatty acid transporters. A better understanding of the molecular mechanism of intestinal fatty acid absorption should lead to novel approaches to the treatment and the prevention of fatty acid-related metabolic diseases that are prevalent worldwide. © 2013 Stichting European Society for Clinical Investigation Journal Foundation. Published by John Wiley & Sons Ltd.

  18. Laser engines operating by resonance absorption.

    PubMed

    Garbuny, M; Pechersky, M J

    1976-05-01

    The coherence properties and power levels of lasers available at present lend themselves to the remote operation of mechanical engines by resonance absorption in a working gas. Laser radiation is capable of producing extremely high temperatures in a gas. Limits to the achievable temperatures in the working gas of an engine are imposed by the solid walls and by loss of resonance absorption due to thermal saturation, bleaching, and dissociation. However, it is shown that by proper control of the laser beam in space, time, and frequency, as well as by choice of the absorbing gas, these limits are to a great extent removed so that very high temperatures are indeed attainable. The working gas is largely monatomic, preferably helium with the addition of a few volume percent of an absorber. Such a gas mixture, internally heated, permits an optimization of the expansion ratio, with resulting thermal efficiencies and work ratios, not achievable in conventional engines. A relationship between thermal efficiency and work ratio is derived that is quite general for the optimization condition. The performance of laser piston engines, turbines, and the Stirling cycle based on these principles is discussed and compared with conventional engine operation. Finally, a brief discussion is devoted to the possibility and concepts for the direct conversion of selective vibrational or electronic excitation into mechanical work, bypassing the translational degrees of freedom.

  19. Quality improvements in decreasing medication administration errors made by nursing staff in an academic medical center hospital: a trend analysis during the journey to Joint Commission International accreditation and in the post-accreditation era

    PubMed Central

    Wang, Hua-fen; Jin, Jing-fen; Feng, Xiu-qin; Huang, Xin; Zhu, Ling-ling; Zhao, Xiao-ying; Zhou, Quan

    2015-01-01

    (1.81% versus 0.24%, P<0.001). Conclusion A 3-and-a-half-year intervention program on MAEs was confirmed to be effective. MAEs made by nursing staff can be reduced, but cannot be eliminated. The depth, breadth, and efficiency of multidiscipline collaboration among physicians, pharmacists, nurses, information engineers, and hospital administrators are pivotal to safety in medication administration. JCI accreditation may help health systems enhance the awareness and ability to prevent MAEs and achieve successful quality improvements. PMID:25767393

  20. Quality improvements in decreasing medication administration errors made by nursing staff in an academic medical center hospital: a trend analysis during the journey to Joint Commission International accreditation and in the post-accreditation era.

    PubMed

    Wang, Hua-Fen; Jin, Jing-Fen; Feng, Xiu-Qin; Huang, Xin; Zhu, Ling-Ling; Zhao, Xiao-Ying; Zhou, Quan

    2015-01-01

    .001). A 3-and-a-half-year intervention program on MAEs was confirmed to be effective. MAEs made by nursing staff can be reduced, but cannot be eliminated. The depth, breadth, and efficiency of multidiscipline collaboration among physicians, pharmacists, nurses, information engineers, and hospital administrators are pivotal to safety in medication administration. JCI accreditation may help health systems enhance the awareness and ability to prevent MAEs and achieve successful quality improvements.

  1. Broadband absorption enhancement in amorphous Si solar cells using metal gratings and surface texturing

    NASA Astrophysics Data System (ADS)

    Magdi, Sara; Swillam, Mohamed A.

    2017-02-01

    The efficiencies of thin film amorphous silicon (a-Si) solar cells are restricted by the small thickness required for efficient carrier collection. This thickness limitations result in poor light absorption. In this work, broadband absorption enhancement is theoretically achieved in a-Si solar cells by using nanostructured back electrode along with surface texturing. The back electrode is formed of Au nanogratings and the surface texturing consists of Si nanocones. The results were then compared to random texturing surfaces. Three dimensional finite difference time domain (FDTD) simulations are used to design and optimize the structure. The Au nanogratings achieved absorption enhancement in the long wavelengths due to sunlight coupling to surface plasmon polaritons (SPP) modes. High absorption enhancement was achieved at short wavelengths due to the decreased reflection and enhanced scattering inside the a-Si absorbing layer. Optimizations have been performed to obtain the optimal geometrical parameters for both the nanogratings and the periodic texturing. In addition, an enhancement factor (i.e. absorbed power in nanostructured device/absorbed power in reference device) was calculated to evaluate the enhancement obtained due to the incorporation of each nanostructure.

  2. Pump absorption in coiled and twisted double-clad hexagonal fiber: effect of launching conditions and core location

    NASA Astrophysics Data System (ADS)

    Dalidet, Romain; Peterka, Pavel; Doya, Valérie; Aubrecht, Jan; Koška, Pavel

    2018-02-01

    Ever extending applications of fiber lasers require energy efficient, high-power, small footprint and reliable fiber lasers and laser wavelength versatility. To meet these demands, next generation of active fibers for high-power fiber lasers is coming out that will eventually offer tailored spectroscopic properties, high robustness and reduced cooling requirements and improved efficiency through tailored pump absorption. We report on numerical modelling of the efficiency of the pump absorption in double clad active fibers with hexagonal shape of the inner cladding cross section and rare-earth-doped core. We analyze both the effect of different radii of the spool on which the fiber is coiled and different fiber twisting rates. Two different launching conditions were investigated: the Gaussian input pump beam and a speckle pattern that mimics the output of the pump laser diode pigtail. We have found that by asymmetric position of the rare-earth-doped core we can significantly improve the pump absorption.

  3. A new concept of efficient therapeutic drug monitoring using the high-resolution continuum source absorption spectrometry and the surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Xing, Yanlong; Fuss, Harald; Lademann, Jürgen; Huang, Mao Dong; Becker-Ross, Helmut; Florek, Stefan; Patzelt, Alexa; Meinke, Martina C.; Jung, Sora; Esser, Norbert

    2018-04-01

    In this study, a new therapeutic drug monitoring approach has been tested based on the combination of CaF molecular absorption using high-resolution continuum source absorption spectrometry (HR-CSAS) and surface enhanced Raman spectroscopy (SERS). HR-CSAS with mini graphite tube was successfully tested for clinical therapeutic drug monitoring of the fluorine-containing drug capecitabine in sweat samples of cancer patients: It showed advantageous features of high selectivity (no interference from Cl), high sensitivity (characteristic mass of 0.1 ng at CaF 583.069 nm), low sample consumption (down to 30 nL) and fast measurement (no sample pretreatment and less than 1 min of responding time) in tracing the fluorine signal out of capecitabine. However, this technique has the disadvantage of the total loss of the drug's structure information after burning the sample at very high temperature. Therefore, a new concept of combining HR-CSAS with a non-destructive spectroscopic method (SERS) was proposed for the sensitive sensing and specific identification of capecitabine. We tested and succeed in obtaining the molecular characteristics of the metabolite of capecitabine (named 5-fluorouracil) by the non-destructive SERS technique. With the results shown in this work, it is demonstrated that the combined spectroscopic technique of HR-CSAS and SERS will be very useful in efficient therapeutic drug monitoring in the future.

  4. Near unity ultraviolet absorption in graphene without patterning

    NASA Astrophysics Data System (ADS)

    Zhu, Jinfeng; Yan, Shuang; Feng, Naixing; Ye, Longfang; Ou, Jun-Yu; Liu, Qing Huo

    2018-04-01

    Enhancing the light-matter interaction of graphene is an important issue for related photonic devices and applications. In view of its potential ultraviolet applications, we aim to achieve extremely high ultraviolet absorption in graphene without any nanostructure or microstructure patterning. By manipulating the polarization and angle of incident light, the ultraviolet power can be sufficiently coupled to the optical dissipation of graphene based on single-channel coherent perfect absorption in an optimized multilayered thin film structure. The ultraviolet absorbance ratios of single and four atomic graphene layers are enhanced up to 71.4% and 92.2%, respectively. Our research provides a simple and efficient scheme to trap ultraviolet light for developing promising photonic and optoelectronic devices based on graphene and potentially other 2D materials.

  5. Improvement of the COP of the LiBr-Water Double-Effect Absorption Cycles

    NASA Astrophysics Data System (ADS)

    Shitara, Atsushi

    Prevention of the global warming has called for a great necessity for energy saving. This applies to the improvement of the COP of absorption chiller-heaters. We started the development of the high efficiency gas-fired double-effect absorption chiller-heater using LiBr-H2O to achieve target performance in short or middle term. To maintain marketability, the volume of the high efficiency machine has been set below the equal to the conventional machine. The absorption cycle technology for improving the COP and the element technology for downsizing the machine is necessary in this development. In this study, the former is investigated. In this report, first of all the target performance has been set at cooling COP of 1.35(on HHV), which is 0.35 higher than the COP of 1.0 for conventional machines in the market. This COP of 1.35 is practically close to the maximum limit achievable by double-effect absorption chiller-heater. Next, the design condition of each element to achieve the target performance and the effect of each mean to improve the COP are investigated. Moreover, as a result of comparing the various flows(series, parallel, reverse)to which the each mean is applied, it has been found the optimum cycle is the parallel flow.

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

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

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

    2016-09-19

    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 subwavelength scale 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 ofmore » 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/cm 2 is achieved in 210 nm thick patterned Si films, yielding a 4-fold increase compared to planar films of the same thickness. As a result, 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.« less

  7. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  8. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, R.C.; Biermann, W.J.

    1989-05-09

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

  9. Metamaterial Receivers for High Efficiency Concentrated Solar Energy Conversion

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

    Yellowhair, Julius E.; Kwon, Hoyeong; Alu, Andrea

    Operation of concentrated solar power receivers at higher temperatures (>700°C) would enable supercritical carbon dioxide (sCO 2) power cycles for improved power cycle efficiencies (>50%) and cost-effective solar thermal power. Unfortunately, radiative losses at higher temperatures in conventional receivers can negatively impact the system efficiency gains. One approach to improve receiver thermal efficiency is to utilize selective coatings that enhance absorption across the visible solar spectrum while minimizing emission in the infrared to reduce radiative losses. Existing coatings, however, tend to degrade rapidly at elevated temperatures. In this report, we report on the initial designs and fabrication of spectrally selectivemore » metamaterial-based absorbers for high-temperature, high-thermal flux environments important for solarized sCO 2 power cycles. Metamaterials are structured media whose optical properties are determined by sub-wavelength structural features instead of bulk material properties, providing unique solutions by decoupling the optical absorption spectrum from thermal stability requirements. The key enabling innovative concept proposed is the use of structured surfaces with spectral responses that can be tailored to optimize the absorption and retention of solar energy for a given temperature range. In this initial study through the Academic Alliance partnership with University of Texas at Austin, we use Tungsten for its stability in expected harsh environments, compatibility with microfabrication techniques, and required optical performance. Our goal is to tailor the optical properties for high (near unity) absorptivity across the majority of the solar spectrum and over a broad range of incidence angles, and at the same time achieve negligible absorptivity in the near infrared to optimize the energy absorbed and retained. To this goal, we apply the recently developed concept of plasmonic Brewster angle to suitably designed nanostructured

  10. Sea surface temperature predictions using a multi-ocean analysis ensemble scheme

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Zhu, Jieshun; Li, Zhongxian; Chen, Haishan; Zeng, Gang

    2017-08-01

    This study examined the global sea surface temperature (SST) predictions by a so-called multiple-ocean analysis ensemble (MAE) initialization method which was applied in the National Centers for Environmental Prediction (NCEP) Climate Forecast System Version 2 (CFSv2). Different from most operational climate prediction practices which are initialized by a specific ocean analysis system, the MAE method is based on multiple ocean analyses. In the paper, the MAE method was first justified by analyzing the ocean temperature variability in four ocean analyses which all are/were applied for operational climate predictions either at the European Centre for Medium-range Weather Forecasts or at NCEP. It was found that these systems exhibit substantial uncertainties in estimating the ocean states, especially at the deep layers. Further, a set of MAE hindcasts was conducted based on the four ocean analyses with CFSv2, starting from each April during 1982-2007. The MAE hindcasts were verified against a subset of hindcasts from the NCEP CFS Reanalysis and Reforecast (CFSRR) Project. Comparisons suggested that MAE shows better SST predictions than CFSRR over most regions where ocean dynamics plays a vital role in SST evolutions, such as the El Niño and Atlantic Niño regions. Furthermore, significant improvements were also found in summer precipitation predictions over the equatorial eastern Pacific and Atlantic oceans, for which the local SST prediction improvements should be responsible. The prediction improvements by MAE imply a problem for most current climate predictions which are based on a specific ocean analysis system. That is, their predictions would drift towards states biased by errors inherent in their ocean initialization system, and thus have large prediction errors. In contrast, MAE arguably has an advantage by sampling such structural uncertainties, and could efficiently cancel these errors out in their predictions.

  11. Water-based metamaterial absorbers for optical transparency and broadband microwave absorption

    NASA Astrophysics Data System (ADS)

    Pang, Yongqiang; Shen, Yang; Li, Yongfeng; Wang, Jiafu; Xu, Zhuo; Qu, Shaobo

    2018-04-01

    Naturally occurring water is a promising candidate for achieving broadband absorption. In this work, by virtue of the optically transparent character of the water, the water-based metamaterial absorbers (MAs) are proposed to achieve the broadband absorption at microwave frequencies and optical transparence simultaneously. For this purpose, the transparent indium tin oxide (ITO) and polymethyl methacrylate (PMMA) are chosen as the constitutive materials. The water is encapsulated between the ITO backed plate and PMMA, serving as the microwave loss as well as optically transparent material. Numerical simulations show that the broadband absorption with the efficiency over 90% in the frequency band of 6.4-30 GHz and highly optical transparency of about 85% in the visible region can be achieved and have been well demonstrated experimentally. Additionally, the proposed water-based MA displays a wide-angle absorption performance for both TE and TM waves and is also robust to the variations of the structure parameters, which is much desired in a practical application.

  12. Gas separation using ultrasound and light absorption

    DOEpatents

    Sinha, Dipen N [Los Alamos, NM

    2012-07-31

    An apparatus and method for separating a chosen gas from a mixture of gases having no moving parts and utilizing no chemical processing is described. The separation of particulates from fluid carriers thereof has been observed using ultrasound. In a similar manner, molecular species may be separated from carrier species. It is also known that light-induced drift may separate light-absorbing species from carrier species. Therefore, the combination of temporally pulsed absorption of light with ultrasonic concentration is expected to significantly increase the efficiency of separation by ultrasonic concentration alone. Additionally, breaking the spatial symmetry of a cylindrical acoustic concentrator decreases the spatial distribution of the concentrated particles, and increases the concentration efficiency.

  13. Radiation absorption and optimization of solar photocatalytic reactors for environmental applications.

    PubMed

    Colina-Márquez, Jose; Machuca-Martínez, Fiderman; Li Puma, Gianluca

    2010-07-01

    This study provides a systematic and quantitative approach to the analysis and optimization of solar photocatalytic reactors utilized in environmental applications such as pollutant remediation and conversion of biomass (waste) to hydrogen. Ray tracing technique was coupled with the six-flux absorption scattering model (SFM) to analyze the complex radiation field in solar compound parabolic collectors (CPC) and tubular photoreactors. The absorption of solar radiation represented by the spatial distribution of the local volumetric rate of photon absorption (LVRPA) depends strongly on catalyst loading and geometry. The total radiation absorbed in the reactors, the volumetric rate of absorption (VRPA), was analyzed as a function of the optical properties (scattering albedo) of the photocatalyst. The VRPA reached maxima at specific catalyst concentrations in close agreement with literature experimental studies. The CPC has on average 70% higher photon absorption efficiency than a tubular reactor and requires 39% less catalyst to operate under optimum conditions. The "apparent optical thickness" is proposed as a new dimensionless parameter for optimization of CPC and tubular reactors. It removes the dependence of the optimum catalyst concentration on tube diameter and photocatalyst scattering albedo. For titanium dioxide (TiO(2)) Degussa P25, maximum photon absorption occurs at apparent optical thicknesses of 7.78 for CPC and 12.97 for tubular reactors.

  14. A Closer look at calcium absorption and the benefits and risks of dietary versus supplemental calcium.

    PubMed

    Booth, Anna; Camacho, Pauline

    2013-11-01

    To perform a thorough search of the literature on calcium research and specifically address the topic of calcium absorption. PubMed and Ovid were the main engines used for primary literature searches; textbooks, review articles, and book chapters are examples of the other sources used for supplemental information. Regarding calcium absorption, it seems apparent that the absorption efficiency of all calcium salts, regardless of solubility, is fairly equivalent and not significantly less than the absorption efficiency of dietary calcium. However, dietary calcium has been shown to have greater impact in bone building than supplemental calcium. This is likely due to improved absorption with meals and the tendency of people to intake smaller amounts more frequently, which is more ideal for the body's method of absorption. In addition, the cardiovascular risks of excessive calcium intake appear to be more closely related to calcium supplements than dietary calcium; this relationship continues to be controversial in the literature. We conclude that further studies are needed for direct comparison of supplemental and dietary calcium to fully establish if one is superior to the other with regard to improving bone density. We also propose further studies on the cardiovascular risk of long-term increased calcium intake and on physician estimates of patients' daily calcium intake to better pinpoint those patients who require calcium supplementation.

  15. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  16. Fat digestion and absorption in spice-pretreated rats.

    PubMed

    Prakash, Usha N S; Srinivasan, Krishnapura

    2012-02-01

    A few common spices are known to stimulate secretion of bile with higher amount of bile acids which play a major role in digestion and absorption of dietary lipids. It would be appropriate to verify if these spices enable efficient digestion and absorption during high-fat intake. In this context, dietary ginger (0.05%), piperine (0.02%), capsaicin (0.015%), and curcumin (0.5%) were examined for their influence on bile secretion, digestive enzymes of pancreas and absorption of dietary fat in high-fat (30%) fed Wistar rats for 8 weeks. These spices enhanced the activity of pancreatic lipase, amylase, trypsin and chymotrypsin by 22-57%, 32-51%, 63-81% and 12-38%, respectively. Dietary intake of spices along with high-fat enhanced fat absorption. These dietary spices increased bile secretion with higher bile acid content. Stimulation of lipid mobilisation from adipose tissue was suggested by the decrease in perirenal adipose tissue weight by dietary capsaicin and piperine. This was also accompanied by prevention of the accumulation of triglyceride in liver and serum in high-fat fed rats. Activities of key lipogenic enzymes in liver were reduced which was accompanied by an increased activity of hormone-sensitive lipase. Thus, dietary ginger and other spice compounds enhance fat digestion and absorption in high-fat fed situation through enhanced secretion of bile salts and a stimulation of the activity pancreatic lipase. At the same time, the energy expenditure is facilitated by these spices to prevent the accumulation of absorbed fat. Copyright © 2011 Society of Chemical Industry.

  17. Tunable integration of absorption-membrane-adsorption for efficiently separating low boiling gas mixtures near normal temperature

    PubMed Central

    Liu, Huang; Pan, Yong; Liu, Bei; Sun, Changyu; Guo, Ping; Gao, Xueteng; Yang, Lanying; Ma, Qinglan; Chen, Guangjin

    2016-01-01

    Separation of low boiling gas mixtures is widely concerned in process industries. Now their separations heavily rely upon energy-intensive cryogenic processes. Here, we report a pseudo-absorption process for separating low boiling gas mixtures near normal temperature. In this process, absorption-membrane-adsorption is integrated by suspending suitable porous ZIF material in suitable solvent and forming selectively permeable liquid membrane around ZIF particles. Green solvents like water and glycol were used to form ZIF-8 slurry and tune the permeability of liquid membrane surrounding ZIF-8 particles. We found glycol molecules form tighter membrane while water molecules form looser membrane because of the hydrophobicity of ZIF-8. When using mixing solvents composed of glycol and water, the permeability of liquid membrane becomes tunable. It is shown that ZIF-8/water slurry always manifests remarkable higher separation selectivity than solid ZIF-8 and it could be tuned to further enhance the capture of light hydrocarbons by adding suitable quantity of glycol to water. Because of its lower viscosity and higher sorption/desorption rate, tunable ZIF-8/water-glycol slurry could be readily used as liquid absorbent to separate different kinds of low boiling gas mixtures by applying a multistage separation process in one traditional absorption tower, especially for the capture of light hydrocarbons. PMID:26892255

  18. Two-photon absorption by spectrally shaped entangled photons

    NASA Astrophysics Data System (ADS)

    Oka, Hisaki

    2018-03-01

    We theoretically investigate two-photon excitation by spectrally shaped entangled photons with energy anticorrelation in terms of how the real excitation of an intermediate state affects two-photon absorption by entangled photons. Spectral holes are introduced in the entangled photons around the energy levels of an intermediate state so that two-step excitation via the real excitation of the intermediated state can be suppressed. Using a three-level atomic system as an example, we show that the spectral holes well suppress the real excitation of the intermediate state and recover two-photon absorption via a virtual state. Furthermore, for a short pulse close to a monocycle, we show that the excitation efficiency by the spectrally shaped entangled photons can be enhanced a thousand times as large as that by uncorrelated photons.

  19. Fat-soluble vitamin intestinal absorption: absorption sites in the intestine and interactions for absorption.

    PubMed

    Goncalves, Aurélie; Roi, Stéphanie; Nowicki, Marion; Dhaussy, Amélie; Huertas, Alain; Amiot, Marie-Josèphe; Reboul, Emmanuelle

    2015-04-01

    The interactions occurring at the intestinal level between the fat-soluble vitamins A, D, E and K (FSVs) are poorly documented. We first determined each FSV absorption profile along the duodenal-colonic axis of mouse intestine to clarify their respective absorption sites. We then investigated the interactions between FSVs during their uptake by Caco-2 cells. Our data show that vitamin A was mostly absorbed in the mouse proximal intestine, while vitamin D was absorbed in the median intestine, and vitamin E and K in the distal intestine. Significant competitive interactions for uptake were then elucidated among vitamin D, E and K, supporting the hypothesis of common absorption pathways. Vitamin A also significantly decreased the uptake of the other FSVs but, conversely, its uptake was not impaired by vitamins D and K and even promoted by vitamin E. These results should be taken into account, especially for supplement formulation, to optimise FSV absorption. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Ionic liquid-based microwave-assisted extraction of flavonoids from Bauhinia championii (Benth.) Benth.

    PubMed

    Xu, Wei; Chu, Kedan; Li, Huang; Zhang, Yuqin; Zheng, Haiyin; Chen, Ruilan; Chen, Lidian

    2012-12-03

    An ionic liquids (IL)-based microwave-assisted approach for extraction and determination of flavonoids from Bauhinia championii (Benth.) Benth. was proposed for the first time. Several ILs with different cations and anions and the microwave-assisted extraction (MAE) conditions, including sample particle size, extraction time and liquid-solid ratio, were investigated. Two M 1-butyl-3-methylimidazolium bromide ([bmim] Br) solution with 0.80 M HCl was selected as the optimal solvent. Meanwhile the optimized conditions a ratio of liquid to material of 30:1, and the extraction for 10 min at 70 °C. Compared with conventional heat-reflux extraction (CHRE) and the regular MAE, IL-MAE exhibited a higher extraction yield and shorter extraction time (from 1.5 h to 10 min). The optimized extraction samples were analysed by LC-MS/MS. IL extracts of Bauhinia championii (Benth.)Benth consisted mainly of flavonoids, among which myricetin, quercetin and kaempferol, β-sitosterol, triacontane and hexacontane were identified. The study indicated that IL-MAE was an efficient and rapid method with simple sample preparation. LC-MS/MS was also used to determine the chemical composition of the ethyl acetate/MAE extract of Bauhinia championii (Benth.) Benth, and it maybe become a rapid method to determine the composition of new plant extracts.

  1. Evaluating Energy Conversion Efficiency

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Smith, B. T.; Buoncristiani, A. M.

    1983-01-01

    Devices that convert solar radiation directly into storable chemical or electrical energy, have characteristic energy absorption spectrum; specifically, each of these devices has energy threshold. The conversion efficiency of generalized system that emcompasses all threshold devices is analyzed, resulting in family of curves for devices of various threshold energies operating at different temperatures.

  2. Enhanced light absorptivity of black carbon with air pollution development in urban Beijing, China

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Zhang, Q.; Cheng, Y.; Su, H.; He, K.

    2017-12-01

    The impacts of black carbon (BC) aerosols on air quality and climate are dependent on BC light absorptivity. However, the light absorptivity of ambient BC-containing particles remains conflicting. In this work, we investigated the evolution of BC light absorptivity with pollution development in urban Beijing, China. We found that the mass absorption cross-section (MAC) of ambient BC-containing particles measured during the campaign increased with BC mass concentration, which can be attributed to more coating materials on BC surface with pollution development. A single-particle soot photometer (SP2) measurement showed that the coating thickness (CT) of BC-containing particles increased by 48% with PM1 and BC mass concentration increasing from 10 μg m-3 and 0.3 μg m-3 to 230 μg m-3 and 12 μg m-3. Based on Mie calculation, the CT increase could led to light absorption enhancement (Eab) of BC-containing particles increasing by 22%, consistent with the increase of measured MAC. The relationship between growth rate of BC light absorptivity (kEab) and that of PM1 or rBC concentration (kPM1 or krBC) showed that kEab ≈ 4.8% kPM1 or kEab ≈ 2.5% krBC. The analysis of effective emission intensity (EEI) for BC revealed that the enhancement of BC light absorptivity with increasing pollution levels was dominated by regional transport. During the pollution period, 63% of BC over Beijing originated from regional sources. The aging of these regional BC during atmospheric transport controlled the increase of coating materials for BC-containing particles observed in Beijing. As a result of enhanced light absorptivity with pollution development, BC forcing efficiency could increase by 20% during polluted period. Our work identified the importance of BC on radiative forcing under polluted environment, which is determined by not only the increase of BC mass concentration, but also the enhancement of BC forcing efficiency due to more coating materials.

  3. Constant Head Evaluation of Full Scale Soil Absorption Fields

    NASA Astrophysics Data System (ADS)

    Dix, S. P.

    2001-05-01

    Design loading rates for septic tank effluent in trenches of various designs with different geometry and media has been debated for decades. The role of bottom and sidewall is a hot topic with many opinion by experts in the field of agricultural and environmental engineering. Research institutions have conducted numerous studies and developed procedures for measuring both test systems and fundamental of soil hydraulics. Falling head tests have been used more recently to evaluate mature test cells and evaluate both sidewall and basal absorption, (Keys et al). The proposed paper will discuss the design and testing of a constant head permeameter. Testing this equipment and developing the test protocol followed the application of the procedure to on a number of residential systems in both sandy and clay loam soil. Results from this testing showed the relability step that must be taken to successfully use this equipment. Result of the testing show the variability and consistency of absorption, the changes in absorption when systems are flooded above their equilibrium condition and the longer-term changes that occur when trenches are rested in a warm climate. More recent application of the test procedure evaluated affects of head and increased depth sidewall on absorption rates when the effluent level in the trenches was raised. Future modification of the test equipment and procedure by integrating a data logger will permits more exact recording of dose cycles and improved estimate of soil absorption efficiency over time.

  4. Single-photon absorption by single photosynthetic light-harvesting complexes

    NASA Astrophysics Data System (ADS)

    Chan, Herman C. H.; Gamel, Omar E.; Fleming, Graham R.; Whaley, K. Birgitta

    2018-03-01

    We provide a unified theoretical approach to the quantum dynamics of absorption of single photons and subsequent excitonic energy transfer in photosynthetic light-harvesting complexes. Our analysis combines a continuous mode < n > -photon quantum optical master equation for the chromophoric system with the hierarchy of equations of motion describing excitonic dynamics in presence of non-Markovian coupling to vibrations of the chromophores and surrounding protein. We apply the approach to simulation of absorption of single-photon coherent states by pigment-protein complexes containing between one and seven chromophores, and compare with results obtained by excitation using a thermal radiation field. We show that the values of excitation probability obtained under single-photon absorption conditions can be consistently related to bulk absorption cross-sections. Analysis of the timescale and efficiency of single-photon absorption by light-harvesting systems within this full quantum description of pigment-protein dynamics coupled to a quantum radiation field reveals a non-trivial dependence of the excitation probability and the excited state dynamics induced by exciton-phonon coupling during and subsequent to the pulse, on the bandwidth of the incident photon pulse. For bandwidths equal to the spectral bandwidth of Chlorophyll a, our results yield an estimation of an average time of ˜0.09 s for a single chlorophyll chromophore to absorb the energy equivalent of one (single-polarization) photon under irradiation by single-photon states at the intensity of sunlight.

  5. The effect of poorly absorbed solute on intestinal absorption.

    PubMed

    Menzies, I S; Jenkins, A P; Heduan, E; Catt, S D; Segal, M B; Creamer, B

    1990-12-01

    To determine the effects of poorly absorbed solute on intestinal absorption, the urinary recovery of ingested lactulose, L-rhamnose, D-xylose, and 3-O-methyl-D-glucose was measured after simultaneous ingestion of various 'loads' of mannitol given in iso-osmolar solution. Mannitol reduced intestinal uptake of the poorly absorbed test sugars, lactulose and L-rhamnose; uptake of D-xylose and 3-O-methyl-D-glucose, which are absorbed by carrier-mediated transport largely from the jejunum, was less affected. The dose-response effect of mannitol on the absorption of L-rhamnose was approximately exponential; doses of 5, 10, and 20 g mannitol reduced the average urinary excretion of L-rhamnose by 34.7%, 51.7%, and 61.2%, respectively. In this respect, an osmotically equivalent load of lactulose, ingested as 'solute', was approximately twice as effective as mannitol in reducing L-rhamnose absorption, probably because lactulose is more poorly absorbed than mannitol (less than 1.0% versus 32-41%). Ingestion of other poorly absorbed solutes such as raffinose, sorbitol, xylitol, magnesium sulphate, and sodium sulphate also significantly depressed the absorption of L-rhamnose; in contrast, more efficiently absorbed solutes, such as sodium chloride, glucose, glycerol, and urea had little effect.

  6. A transform from absorption to Raman excitation profile. A time-dependent approach

    NASA Astrophysics Data System (ADS)

    Lee, Soo-Y.; Yeo, Robert C. K.

    1994-04-01

    An alternative time-frame approach, which is canonically conjugate to the energy-frame approach, for implementing the transform relations for calculating Raman excitation profiles directly from the optical absorption spectrum is presented. Practical and efficient fast Fourier transformation in the time frame replaces the widely used Chan and Page algorithm for evaluating the Hilbert transform in the energy frame. The time-frame approach is applied to: (a) a two-mode model which illustrates the missing mode effect in both absorption and Raman excitation profiles, (b) carotene, in which both the absorption spectrum and the Raman excitation profile show vibrational structure and (c) hexamethylbenzene: TCNE electron donor—acceptor complex where the same spectra are structureless and the Raman excitation profile for the 168 cm -1 mode poses a problem for the energy-frame approach. A similar time-frame approach can be used for the inverse transform from the Raman excitation profile to the optical absorption spectrum.

  7. Broad-spectrum enhanced absorption of graphene-molybdenum disulfide photovoltaic cells in metal-mirror microcavity.

    PubMed

    Jiang-Tao, Liu; Yun-Kai, Cao; Hong, Tong; Dai-Qiang, Wang; Zhen-Hua, Wu

    2018-04-06

    The optical absorption of graphene-molybdenum disulfide photovoltaic cells (GM-PVc) in wedge-shaped metal-mirror microcavities (w-MMCs) combined with a spectrum-splitting structure was studied. Results showed that the combination of spectrum-splitting structure and w-MMC can enable the light absorption of GM-PVcs to reach about 65% in the broad spectrum. The influence of processing errors on the absorption of GM-PVcs in w-MMCs was 3-14 times lower than that of GM-PVcs in wedge photonic crystal microcavities. The light absorption of GM-PVcs reached 60% in the broad spectrum, even with the processing errors. The proposed structure is easy to implement and may have potentially important applications in the development of ultra-thin and high-efficiency solar cells and optoelectronic devices.

  8. Broad-spectrum enhanced absorption of graphene-molybdenum disulfide photovoltaic cells in metal-mirror microcavity

    NASA Astrophysics Data System (ADS)

    Jiang-Tao, Liu; Yun-Kai, Cao; Hong, Tong; Dai-Qiang, Wang; Zhen-Hua, Wu

    2018-04-01

    The optical absorption of graphene-molybdenum disulfide photovoltaic cells (GM-PVc) in wedge-shaped metal-mirror microcavities (w-MMCs) combined with a spectrum-splitting structure was studied. Results showed that the combination of spectrum-splitting structure and w-MMC can enable the light absorption of GM-PVcs to reach about 65% in the broad spectrum. The influence of processing errors on the absorption of GM-PVcs in w-MMCs was 3-14 times lower than that of GM-PVcs in wedge photonic crystal microcavities. The light absorption of GM-PVcs reached 60% in the broad spectrum, even with the processing errors. The proposed structure is easy to implement and may have potentially important applications in the development of ultra-thin and high-efficiency solar cells and optoelectronic devices.

  9. Evaluation of the essential oil of Foeniculum vulgare Mill (fennel) fruits extracted by three different extraction methods by GC/MS.

    PubMed

    Hammouda, Faiza M; Saleh, Mahmoud A; Abdel-Azim, Nahla S; Shams, Khaled A; Ismail, Shams I; Shahat, Abdelaaty A; Saleh, Ibrahim A

    2014-01-01

    Hydrodistillation (HD) and steam-distillation, or solvent extraction methods of essential oils have some disadvantages like thermal decomposition of extracts, its contamination with solvent or solvent residues and the pollution of residual vegetal material with solvent which can be also an environmental problem. Thus, new green techniques, such as supercritical fluid extraction and microwave assisted techniques, are potential solutions to overcome these disadvantages. The aim of this study was to evaluate the essential oil of Foeniculum vulgare subsp. Piperitum fruits extracted by three different extraction methods viz. Supercritical fluid extraction (SFE) using CO2, microwave-assisted extraction (MAE) and hydro-distillation (HD) using gas chromatography-mass spectrometry (GC/MS). The results revealed that both MAE and SFE enhanced the extraction efficiency of the interested components. MAE gave the highest yield of oil as well as higher percentage of Fenchone (28%), whereas SFE gave the highest percentage of anethol (72%). Microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE) not only enhanced the essential oil extraction but also saved time, reduced the solvents use and produced, ecologically, green technologies.

  10. Evaluation of Enthalpy Diagrams for NH3-H2O Absorption Refrigerator

    NASA Astrophysics Data System (ADS)

    Takei, Toshitaka; Saito, Kiyoshi; Kawai, Sunao

    The protection of environment is becoming a grave problem nowadays and an absorption refrigerator, which does not use fleon as a refrigerant, is acquiring a close attention. Among the absorption refrigerators, a number of ammonia-water absorption refrigerators are being used in realm such as refrigeration and ice accumulation, since this type of refrigerator can produce below zero degree products. It is essential to conduct an investigation on the characteristics of ammonia-water absorption refrigerator in detail by means of computer simulation in order to realize low cost, highly efficient operation. Unfortunately, there have been number of problems in order to conduct computer simulations. Firstly, Merkel's achievements of enthalpy diagram does not give the relational equations. And secondly, although relational equation are being proposed by Ziegler, simpler equations that can be applied to computer simulation are yet to be proposed. In this research, simper equations based on Ziegler's equations have been derived to make computer simulation concerning the performance of ammonia-water absorption refrigerator possible-Both results of computer simulations using simple equations and Merkel's enthalpy diagram respectively, have been compared with the actual experimental data of one staged ammonia-water absorption refrigerator. Consequently, it is clarified that the results from Ziegler's equations agree with experimental data better than those from Merkel's enthalpy diagram.

  11. Metasurface Salisbury screen: achieving ultra-wideband microwave absorption.

    PubMed

    Zhou, Ziheng; Chen, Ke; Zhao, Junming; Chen, Ping; Jiang, Tian; Zhu, Bo; Feng, Yijun; Li, Yue

    2017-11-27

    The metasurfaces have recently been demonstrated to provide full control of the phase responses of electromagnetic (EM) wave scattering over subwavelength scales, enabling a wide range of practical applications. Here, we propose a comprehensive scheme for the efficient and flexible design of metasurface Salisbury screen (MSS) capable of absorbing the impinging EM wave in an ultra-wide frequency band. We show that properly designed reflective metasurface can be used to substitute the metallic ground of conventional Salisbury screen for generating diverse resonances in a desirable way, thus providing large controllability over the absorption bandwidth. Based on this concept, we establish an equivalent circuit model to qualitatively analysis the resonances in MSS and design algorithms to optimize the overall performance of the MSS. Experiments have been carried out to demonstrate that the absorption bandwidth from 6 GHz to 30 GHz with an efficiency higher than 85% can be achieved by the proposal, which is apparently much larger than that of conventional Salisbury screen (7 GHz - 17 GHz). The proposed concept of MSS could offer opportunities for flexibly designing thin electromagnetic absorbers with simultaneously ultra-wide bandwidth, polarization insensitivity, and wide incident angle, exhibiting promising potentials for many applications such as in EM compatibility, stealth technique, etc.

  12. Enhancing the absorption and energy transfer process via quantum entanglement

    NASA Astrophysics Data System (ADS)

    Zong, Xiao-Lan; Song, Wei; Zhou, Jian; Yang, Ming; Yu, Long-Bao; Cao, Zhuo-Liang

    2018-07-01

    The quantum network model is widely used to describe the dynamics of excitation energy transfer in photosynthesis complexes. Different from the previous schemes, we explore a specific network model, which includes both light-harvesting and energy transfer process. Here, we define a rescaled measure to manifest the energy transfer efficiency from external driving to the sink, and the external driving fields are used to simulate the energy absorption process. To study the role of initial state in the light-harvesting and energy transfer process, we assume the initial state of the donors to be two-qubit and three-qubit entangled states, respectively. In the two-qubit initial state case, we find that the initial entanglement between the donors can help to improve the absorption and energy transfer process for both the near-resonant and large-detuning cases. For the case of three-qubit initial state, we can see that the transfer efficiency will reach a larger value faster in the tripartite entanglement case compared to the bipartite entanglement case.

  13. Low-Cost, High Efficiency, Silicon Based Photovoltaic Devices

    DTIC Science & Technology

    2015-08-27

    for photovoltaic applications. Figure 14: (a) Absorption and scattering efficiencies versus sizes of Au nanoparticle at 550 nm, (b) scattering...efficiency as a function of wavelength for different Au nanoparticles sizes . 32 Review of plasmonics light trapping for photovoltaic application...ensure that the irradiation variation was within 3%. The external quantum efficiency (EQE) system used a 300W Xenon light source with a spot size of 1mm

  14. Large-scale cauliflower-shaped hierarchical copper nanostructures for efficient photothermal conversion.

    PubMed

    Fan, Peixun; Wu, Hui; Zhong, Minlin; Zhang, Hongjun; Bai, Benfeng; Jin, Guofan

    2016-08-14

    Efficient solar energy harvesting and photothermal conversion have essential importance for many practical applications. Here, we present a laser-induced cauliflower-shaped hierarchical surface nanostructure on a copper surface, which exhibits extremely high omnidirectional absorption efficiency over a broad electromagnetic spectral range from the UV to the near-infrared region. The measured average hemispherical absorptance is as high as 98% within the wavelength range of 200-800 nm, and the angle dependent specular reflectance stays below 0.1% within the 0-60° incident angle. Such a structured copper surface can exhibit an apparent heating up effect under the sunlight illumination. In the experiment of evaporating water, the structured surface yields an overall photothermal conversion efficiency over 60% under an illuminating solar power density of ∼1 kW m(-2). The presented technology provides a cost-effective, reliable, and simple way for realizing broadband omnidirectional light absorptive metal surfaces for efficient solar energy harvesting and utilization, which is highly demanded in various light harvesting, anti-reflection, and photothermal conversion applications. Since the structure is directly formed by femtosecond laser writing, it is quite suitable for mass production and can be easily extended to a large surface area.

  15. Effective light absorption and its enhancement factor for silicon nanowire-based solar cell.

    PubMed

    Duan, Zhiqiang; Li, Meicheng; Mwenya, Trevor; Fu, Pengfei; Li, Yingfeng; Song, Dandan

    2016-01-01

    Although nanowire (NW) antireflection coating can enhance light trapping capability, which is generally used in crystal silicon (CS) based solar cells, whether it can improve light absorption in the CS body depends on the NW geometrical shape and their geometrical parameters. In order to conveniently compare with the bare silicon, two enhancement factors E(T) and E(A) are defined and introduced to quantitatively evaluate the efficient light trapping capability of NW antireflective layer and the effective light absorption capability of CS body. Five different shapes (cylindrical, truncated conical, convex conical, conical, and concave conical) of silicon NW arrays arranged in a square are studied, and the theoretical results indicate that excellent light trapping does not mean more light can be absorbed in the CS body. The convex conical NW has the best light trapping, but the concave conical NW has the best effective light absorption. Furthermore, if the cross section of silicon NW is changed into a square, both light trapping and effective light absorption are enhanced, and the Eiffel Tower shaped NW arrays have optimal effective light absorption.

  16. Laser-absorption sensing of gas composition of products from coal gasification

    NASA Astrophysics Data System (ADS)

    Jeffries, Jay B.; Sur, Ritobrata; Sun, Kai; Hanson, Ronald K.

    2014-06-01

    A prototype in-situ laser-absorption sensor for the real-time composition measurement (CO, CH4, H2O and CO2) of synthesis gas products of coal gasification (called here syngas) was designed, tested in the laboratory, and demonstrated during field-measurement campaigns in a pilot-scale entrained flow gasifier at the University of Utah and in an engineering-scale, fluidized-bed transport gasifier at the National Carbon Capture Center (NCCC). The prototype design and operation were improved by the lessons learned from each field test. Laser-absorption measurements are problematic in syngas flows because efficient gasifiers operate at elevated pressures (10-50 atm) where absorption transitions are collision broadened and absorption transitions that are isolated at 1 atm become blended into complex features, and because syngas product streams can contain significant particulate, producing significant non-absorption scattering losses of the transmission of laser light. Thus, the prototype sensor used a new wavelength-scanned, wavelength-modulation spectroscopy strategy with 2f-detection and 1f-normalization (WMS-2f/1f) that can provide sensitive absorption measurements of species with spectra blended by collision broadening even in the presence of large non-absorption laser transmission losses (e.g., particulate scattering, beam steering, etc.). The design of the sensor for detection of CO, CH4, H2O and CO2 was optimized for the specific application of syngas monitoring at the output of large-scale gasifiers. Sensor strategies, results and lessons learned from these field measurement campaigns are discussed.

  17. An investigation of a mathematical model for atmospheric absorption spectra

    NASA Technical Reports Server (NTRS)

    Niple, E. R.

    1979-01-01

    A computer program that calculates absorption spectra for slant paths through the atmosphere is described. The program uses an efficient convolution technique (Romberg integration) to simulate instrument resolution effects. A brief information analysis is performed on a set of calculated spectra to illustrate how such techniques may be used to explore the quality of the information in a spectrum.

  18. Fructo-oligosaccharides and calcium absorption and retention in adolescent girls.

    PubMed

    Martin, Berdine R; Braun, Michelle M; Wigertz, Karin; Bryant, Rebecca; Zhao, Yongdong; Lee, WangHee; Kempa-Steczko, Ania; Weaver, Connie M

    2010-08-01

    Several studies have shown a positive effect of fructo-oligosaccharides on calcium absorption and retention in animals and humans. Effects of levels of these pre-biotics that can be functionally incorporated into manufactured foods, have not been studied in controlled feeding studies. This study was designed to evaluate the effect of 9 g/d of fructo-oligosaccharides as part of a controlled diet on calcium absorption and retention in adolescent girls. Fourteen healthy adolescent girls aged 11-13 y were studied in a metabolic setting for two 3-week periods separated by a 2-week washout period. In a randomized, double-blinded, crossover design, the teens received a diet containing either 9 g/d oligofructose-enriched inulin in a calcium-fortified cereal or the control cereal with no inulin. Both diets contained ~1500 mg calcium daily. Calcium retention was determined on the third week of each period. On day 14 of the diet period, fractional calcium absorption was determined from the enrichment of (44)Ca in 4-day urine collections. Calcium absorption (67 ± 3 vs. 66 ± 3%) and retention (409 ± 394 vs. 464 ± 241 mg/d) were not significantly different when diets contained 9 g/d oligofructose-enriched inulin or not in a calcium-fortified cereal. Daily consumption of cereal containing a combination of short- and long-chain fructo-oligosaccharides as part of a controlled diet did not benefit calcium absorption or retention in adolescent girls. Lack of response to the prebiotic in this cohort may relate to their already high calcium absorption efficiency.

  19. Mushrooms as Efficient Solar Steam-Generation Devices.

    PubMed

    Xu, Ning; Hu, Xiaozhen; Xu, Weichao; Li, Xiuqiang; Zhou, Lin; Zhu, Shining; Zhu, Jia

    2017-07-01

    Solar steam generation is emerging as a promising technology, for its potential in harvesting solar energy for various applications such as desalination and sterilization. Recent studies have reported a variety of artificial structures that are designed and fabricated to improve energy conversion efficiencies by enhancing solar absorption, heat localization, water supply, and vapor transportation. Mushrooms, as a kind of living organism, are surprisingly found to be efficient solar steam-generation devices for the first time. Natural and carbonized mushrooms can achieve ≈62% and ≈78% conversion efficiencies under 1 sun illumination, respectively. It is found that this capability of high solar steam generation is attributed to the unique natural structure of mushroom, umbrella-shaped black pileus, porous context, and fibrous stipe with a small cross section. These features not only provide efficient light absorption, water supply, and vapor escape, but also suppress three components of heat losses at the same time. These findings not only reveal the hidden talent of mushrooms as low-cost materials for solar steam generation, but also provide inspiration for the future development of high-performance solar thermal conversion devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A cascaded QSAR model for efficient prediction of overall power conversion efficiency of all-organic dye-sensitized solar cells.

    PubMed

    Li, Hongzhi; Zhong, Ziyan; Li, Lin; Gao, Rui; Cui, Jingxia; Gao, Ting; Hu, Li Hong; Lu, Yinghua; Su, Zhong-Min; Li, Hui

    2015-05-30

    A cascaded model is proposed to establish the quantitative structure-activity relationship (QSAR) between the overall power conversion efficiency (PCE) and quantum chemical molecular descriptors of all-organic dye sensitizers. The cascaded model is a two-level network in which the outputs of the first level (JSC, VOC, and FF) are the inputs of the second level, and the ultimate end-point is the overall PCE of dye-sensitized solar cells (DSSCs). The model combines quantum chemical methods and machine learning methods, further including quantum chemical calculations, data division, feature selection, regression, and validation steps. To improve the efficiency of the model and reduce the redundancy and noise of the molecular descriptors, six feature selection methods (multiple linear regression, genetic algorithms, mean impact value, forward selection, backward elimination, and +n-m algorithm) are used with the support vector machine. The best established cascaded model predicts the PCE values of DSSCs with a MAE of 0.57 (%), which is about 10% of the mean value PCE (5.62%). The validation parameters according to the OECD principles are R(2) (0.75), Q(2) (0.77), and Qcv2 (0.76), which demonstrate the great goodness-of-fit, predictivity, and robustness of the model. Additionally, the applicability domain of the cascaded QSAR model is defined for further application. This study demonstrates that the established cascaded model is able to effectively predict the PCE for organic dye sensitizers with very low cost and relatively high accuracy, providing a useful tool for the design of dye sensitizers with high PCE. © 2015 Wiley Periodicals, Inc.

  1. 69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  2. High intersubband absorption in long-wave quantum well infrared photodetector based on waveguide resonance

    NASA Astrophysics Data System (ADS)

    Zheng, Yuanliao; Chen, Pingping; Ding, Jiayi; Yang, Heming; Nie, Xiaofei; Zhou, Xiaohao; Chen, Xiaoshuang; Lu, Wei

    2018-06-01

    A hybrid structure consisting of periodic gold stripes and an overlaying gold film has been proposed as the optical coupler of a long-wave quantum well infrared photodetector. Absorption spectra and field distributions of the structure at back-side normal incidence are calculated by the finite difference time-domain method. The results indicate that the intersubband absorption can be greatly enhanced based on the waveguide resonance as well as the surface plasmon polariton (SPP) mode. With the optimized structural parameters of the periodic gold stripes, the maximal intersubband absorption can exceed 80%, which is much higher than the SPP-enhanced intersubband absorption (<50%) and about 6 times the one of the standard device. The relationship between the structural parameters and the waveguide resonant wavelength is derived. Other advantages of the efficient optical coupling based on waveguide resonance are also discussed.

  3. Large-scale cauliflower-shaped hierarchical copper nanostructures for efficient photothermal conversion

    NASA Astrophysics Data System (ADS)

    Fan, Peixun; Wu, Hui; Zhong, Minlin; Zhang, Hongjun; Bai, Benfeng; Jin, Guofan

    2016-07-01

    Efficient solar energy harvesting and photothermal conversion have essential importance for many practical applications. Here, we present a laser-induced cauliflower-shaped hierarchical surface nanostructure on a copper surface, which exhibits extremely high omnidirectional absorption efficiency over a broad electromagnetic spectral range from the UV to the near-infrared region. The measured average hemispherical absorptance is as high as 98% within the wavelength range of 200-800 nm, and the angle dependent specular reflectance stays below 0.1% within the 0-60° incident angle. Such a structured copper surface can exhibit an apparent heating up effect under the sunlight illumination. In the experiment of evaporating water, the structured surface yields an overall photothermal conversion efficiency over 60% under an illuminating solar power density of ~1 kW m-2. The presented technology provides a cost-effective, reliable, and simple way for realizing broadband omnidirectional light absorptive metal surfaces for efficient solar energy harvesting and utilization, which is highly demanded in various light harvesting, anti-reflection, and photothermal conversion applications. Since the structure is directly formed by femtosecond laser writing, it is quite suitable for mass production and can be easily extended to a large surface area.Efficient solar energy harvesting and photothermal conversion have essential importance for many practical applications. Here, we present a laser-induced cauliflower-shaped hierarchical surface nanostructure on a copper surface, which exhibits extremely high omnidirectional absorption efficiency over a broad electromagnetic spectral range from the UV to the near-infrared region. The measured average hemispherical absorptance is as high as 98% within the wavelength range of 200-800 nm, and the angle dependent specular reflectance stays below 0.1% within the 0-60° incident angle. Such a structured copper surface can exhibit an apparent

  4. Physicochemical properties and cytotoxicity of an experimental resin-based pulp capping material containing the quaternary ammonium salt and Portland cement.

    PubMed

    Yang, Y W; Yu, F; Zhang, H C; Dong, Y; Qiu, Y N; Jiao, Y; Xing, X D; Tian, M; Huang, L; Chen, J H

    2018-01-01

    To evaluate in vitro the physicochemical properties, cytotoxicity and calcium phosphate nucleation of an experimental light-curable pulp capping material composed of a resin with antibacterial monomer (MAE-DB) and Portland cement (PC). The experimental material was prepared by mixing PC with a resin containing MAE-DB at a 2 : 1 ratio. Cured pure resin containing MAE-DB served as control resin. ProRoot MTA and Dycal served as commercial controls. The depth of cure, degree of monomer conversion, water absorption and solubility of dry samples, calcium release, alkalinizing activity, calcium phosphate nucleation and the cytotoxicity of materials were evaluated. Statistical analysis was carried out using anova followed by Tukey's HSD test (equal variance assumed) or Tamhane test (equal variance not assumed) and independent-samples t-tests. The experimental material had a cure depth of 1.19 mm, and the mean degree of monomer conversion was 70.93% immediately post-cure and 88.75% at 24 h post-cure. The water absorption of the experimental material was between those of MTA and Dycal, and its solubility was significantly less (P < 0.05) than that of Dycal and higher than that of MTA. The experimental material exhibited continuous calcium release and an alkalinizing power between those of MTA and Dycal throughout the test period. Freshly set experimental material, control resin and all 24-h set materials had acceptable cytotoxicity. The experimental material, MTA and Dycal all exhibited the formation of apatite precipitates after immersion in phosphate-buffered saline. The experimental material possessed adequate physicochemical properties, low cytotoxicity and good calcium phosphate nucleation. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  5. Hybridization-induced broadband terahertz wave absorption with graphene metasurfaces.

    PubMed

    Mou, Nanli; Sun, Shulin; Dong, Hongxing; Dong, Shaohua; He, Qiong; Zhou, Lei; Zhang, Long

    2018-04-30

    Electromagnetic (EM) wave absorption plays a vital role in photonics. While metasurfaces are proposed to absorb EM waves efficiently, most of them exhibit limited bandwidth and fixed functionalities. Here, we propose a broadband and tunable terahertz (THz) absorber based on a graphene-based metasurface, which is constructed by a single layer of closely patterned graphene concentric double rings and a metallic mirror separated by an ultrathin SiO 2 layer. Plasmonic hybridization between two graphene rings significantly enlarges the absorption bandwidth, which can be further tuned by gating the graphene. Moreover, the specific design also makes our device insensitive to the incident angle and polarization state of impinging EM waves. Our results may inspire certain wave-modulation-related applications, such as THz imaging, smart absorber, tunable sensor, etc.

  6. Self-assembly of highly efficient, broadband plasmonic absorbers for solar steam generation

    PubMed Central

    Zhou, Lin; Tan, Yingling; Ji, Dengxin; Zhu, Bin; Zhang, Pei; Xu, Jun; Gan, Qiaoqiang; Yu, Zongfu; Zhu, Jia

    2016-01-01

    The study of ideal absorbers, which can efficiently absorb light over a broad range of wavelengths, is of fundamental importance, as well as critical for many applications from solar steam generation and thermophotovoltaics to light/thermal detectors. As a result of recent advances in plasmonics, plasmonic absorbers have attracted a lot of attention. However, the performance and scalability of these absorbers, predominantly fabricated by the top-down approach, need to be further improved to enable widespread applications. We report a plasmonic absorber which can enable an average measured absorbance of ~99% across the wavelengths from 400 nm to 10 μm, the most efficient and broadband plasmonic absorber reported to date. The absorber is fabricated through self-assembly of metallic nanoparticles onto a nanoporous template by a one-step deposition process. Because of its efficient light absorption, strong field enhancement, and porous structures, which together enable not only efficient solar absorption but also significant local heating and continuous stream flow, plasmonic absorber–based solar steam generation has over 90% efficiency under solar irradiation of only 4-sun intensity (4 kW m−2). The pronounced light absorption effect coupled with the high-throughput self-assembly process could lead toward large-scale manufacturing of other nanophotonic structures and devices. PMID:27152335

  7. Self-assembly of highly efficient, broadband plasmonic absorbers for solar steam generation.

    PubMed

    Zhou, Lin; Tan, Yingling; Ji, Dengxin; Zhu, Bin; Zhang, Pei; Xu, Jun; Gan, Qiaoqiang; Yu, Zongfu; Zhu, Jia

    2016-04-01

    The study of ideal absorbers, which can efficiently absorb light over a broad range of wavelengths, is of fundamental importance, as well as critical for many applications from solar steam generation and thermophotovoltaics to light/thermal detectors. As a result of recent advances in plasmonics, plasmonic absorbers have attracted a lot of attention. However, the performance and scalability of these absorbers, predominantly fabricated by the top-down approach, need to be further improved to enable widespread applications. We report a plasmonic absorber which can enable an average measured absorbance of ~99% across the wavelengths from 400 nm to 10 μm, the most efficient and broadband plasmonic absorber reported to date. The absorber is fabricated through self-assembly of metallic nanoparticles onto a nanoporous template by a one-step deposition process. Because of its efficient light absorption, strong field enhancement, and porous structures, which together enable not only efficient solar absorption but also significant local heating and continuous stream flow, plasmonic absorber-based solar steam generation has over 90% efficiency under solar irradiation of only 4-sun intensity (4 kW m(-2)). The pronounced light absorption effect coupled with the high-throughput self-assembly process could lead toward large-scale manufacturing of other nanophotonic structures and devices.

  8. X-ray absorption spectroscopy: EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure)

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

    Alp, E.E.; Mini, S.M.; Ramanathan, M.

    1990-04-01

    The x-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. It has also played an important role in the discovery and systematization of rare-earth elements. The discovery of synchrotron radiation in 1952, and later the availability of broadly tunable synchrotron based x-ray sources have revitalized this technique since the 1970's. The correct interpretation of the oscillatory structure in the x-ray absorption cross-section above the absorption edge by Sayers et. al. has transformed XAS from a spectroscopic tool to a structural technique. EXAFS (Extended X-raymore » Absorption Fine Structure) yields information about the interatomic distances, near neighbor coordination numbers, and lattice dynamics. An excellent description of the principles and data analysis techniques of EXAFS is given by Teo. XANES (X-ray Absorption Near Edge Structure), on the other hand, gives information about the valence state, energy bandwidth and bond angles. Today, there are about 50 experimental stations in various synchrotrons around the world dedicated to collecting x-ray absorption data from the bulk and surfaces of solids and liquids. In this chapter, we will give the basic principles of XAS, explain the information content of essentially two different aspects of the absorption process leading to EXAFS and XANES, and discuss the source and samples limitations.« less

  9. Sound absorption by subwavelength membrane structures: A geometric perspective

    NASA Astrophysics Data System (ADS)

    Yang, Min; Li, Yong; Meng, Chong; Fu, Caixing; Mei, Jun; Yang, Zhiyu; Sheng, Ping

    2015-12-01

    Decorated membranes comprising a thin layer of elastic film with small rigid platelets fixed on top have been found to be efficient absorbers of low-frequency sound. In this work we consider the problem of sound absorption from a perspective aimed at deriving upper bounds under different scenarios, i.e., whether the sound is incident from one side only or from both sides, and whether there is a reflecting surface on the back side of the membrane. By considering the negligible thickness of the membrane, usually on the order of a fraction of one millimeter, we derive a relation showing that the sum of the incoming sound waves' (complex) pressure amplitudes, averaged over the area of the membrane, must be equal to that of the outgoing waves. By using this relation, and without going to any details of the wave solutions, it is shown that the maximum absorption achievable from one-sided incidence is 50%, while the maximum absorption with a back-reflecting surface can reach 100%. The latter was attained by the hybridized resonances. All the results are shown to be in excellent agreement with the experiments. This generalized perspective, when used together with the Green function's formalism, can be useful in gaining insights into the constraints on what are achievable in scatterings and absorption by thin film structures and delineating them.

  10. Investigation into the origin of parasitic absorption in GaInP|GaAs double heterostructures

    NASA Astrophysics Data System (ADS)

    Giannini, Nathan; Yang, Zhou; Albrecht, Alexander R.; Sheik-Bahae, Mansoor

    2017-02-01

    Despite achievements of extremely high external quantum efficiency (EQE), 99.5%, the net cooling of GaInP|GaAs double heterostructures (DHS) has never been realized. This is due to an unknown source of parasitic absorption. Prior studies have ruled out the possibility of the bulk absorption from the GaAs layer. Thus it is thought to be either at the air- GaInP interface, through the presence of dangling bonds, or in bulk GaInP through impurities. Using two-color thermallens calorimetry (based on the Z-scan technique), this study indicates that that the parasitic absorption likely originates from the GaInP bulk layers.

  11. 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.

  12. Microwave-Assisted Extraction of Fucoidan from Marine Algae.

    PubMed

    Mussatto, Solange I

    2015-01-01

    Microwave-assisted extraction (MAE) is a technique that can be applied to extract compounds from different natural resources. In this chapter, the use of this technique to extract fucoidan from marine algae is described. The method involves a closed MAE system, ultrapure water as extraction solvent, and suitable conditions of time, pressure, and algal biomass/water ratio. By using this procedure under the specified conditions, the penetration of the electromagnetic waves into the material structure occurs in an efficient manner, generating a distributed heat source that promotes the fucoidan extraction from the algal biomass.

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

    PubMed

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

    2012-12-21

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

  14. Waste heat driven absorption refrigeration process and system

    DOEpatents

    Wilkinson, William H.

    1982-01-01

    Absorption cycle refrigeration processes and systems are provided which are driven by the sensible waste heat available from industrial processes and other sources. Systems are disclosed which provide a chilled water output which can be used for comfort conditioning or the like which utilize heat from sensible waste heat sources at temperatures of less than 170.degree. F. Countercurrent flow equipment is also provided to increase the efficiency of the systems and increase the utilization of available heat.

  15. Microwave-assisted extraction of rutin and quercetin from the stalks of Euonymus alatus (Thunb.) Sieb.

    PubMed

    Zhang, Fan; Yang, Yi; Su, Ping; Guo, Zhenku

    2009-01-01

    Euonymus alatus (Thunb.) has been used as one of traditional Chinese medicines for several thousand years. Conventional methods for the extraction of rutin and quercetin from E. alatus, including solvent extraction, Soxhlet extraction and heat reflux extraction are characterised by long extraction times and consumption of large amounts of solvents. To develop a simple and rapid method for the extraction of rutin and quercetin from the stalks of Euonymus alatus (Thunb.) Sieb using microwave-assisted extraction (MAE) technique. MAE experiments were performed with a multimode microwave extraction system. The experimental variables that affect the MAE process, such as the concentration of ethanol solution, extractant volume, microwave power and extraction time were optimised. Yields were determined by HPLC. The results were compared with that obtained by classical Soxhlet and ultrasonic-assisted extraction (UAE). From the optimised conditions for MAE of rutin and quercetin it can be concluded that the solvent is 50% ethanol (v/v) solution, the extractant volume is 40 mL, microwave power is 170 W and irradiation time is 6 min. Compared with Soxhlet extraction and ultrasonic extraction, microwave extraction is a rapid method with a higher yield and lower solvent consumption. The results showed that MAE can be used as an efficient and rapid method for the extraction of the active components from plants.

  16. 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.

  17. Controlling coulomb interactions in infrared stereometamaterials for unity light absorption

    NASA Astrophysics Data System (ADS)

    Mudachathi, Renilkumar; Moritake, Yuto; Tanaka, Takuo

    2018-05-01

    We investigate the influence of near field interactions between the constituent 3D split ring resonators on the absorbance and resonance frequency of a stereo metamaterial based perfect light absorber. The experimental and theoretical analyses reveal that the magnetic resonance red shifts and broadens for both the decreasing vertical and lateral separations of the constituents within the metamaterial lattice, analogous to plasmon hybridization. The strong interparticle interactions for higher density reduce the effective cross-section per resonator, which results in weak light absorption observed in both experimental and theoretical analyses. The red shift of the magnetic resonance with increasing lattice density is an indication of the dominating electric dipole interactions and we analyzed the metamaterial system in an electrostatic point of view to explain the observed resonance shift and decreasing absorption peak. From these analyses, we found that the fill factor introduces two competing factors determining the absorption efficiency such as coulomb interactions between the constituent resonators and their number density in a given array structure. We predicted unity light absorption for a fill factor of 0.17 balancing these two opposing factors and demonstrate an experimental absorbance of 99.5% at resonance with our 3D device realized using residual stress induced bending of 2D patterns.

  18. Preparation and Sound Absorption Properties of a Barium Titanate/Nitrile Butadiene Rubber–Polyurethane Foam Composite with Multilayered Structure

    PubMed Central

    Jiang, Xueliang; Yang, Zhen; Wang, Zhijie; Zhang, Fuqing; You, Feng

    2018-01-01

    Barium titanate/nitrile butadiene rubber (BT/NBR) and polyurethane (PU) foam were combined to prepare a sound-absorbing material with an alternating multilayered structure. The effects of the cell size of PU foam and the alternating unit number on the sound absorption property of the material were investigated. The results show that the sound absorption efficiency at a low frequency increased when decreasing the cell size of PU foam layer. With the increasing of the alternating unit number, the material shows the sound absorption effect in a wider bandwidth of frequency. The BT/NBR-PU foam composites with alternating multilayered structure have an excellent sound absorption property at low frequency due to the organic combination of airflow resistivity, resonance absorption, and interface dissipation. PMID:29565321

  19. Preparation and Sound Absorption Properties of a Barium Titanate/Nitrile Butadiene Rubber-Polyurethane Foam Composite with Multilayered Structure.

    PubMed

    Jiang, Xueliang; Yang, Zhen; Wang, Zhijie; Zhang, Fuqing; You, Feng; Yao, Chu

    2018-03-22

    Barium titanate/nitrile butadiene rubber (BT/NBR) and polyurethane (PU) foam were combined to prepare a sound-absorbing material with an alternating multilayered structure. The effects of the cell size of PU foam and the alternating unit number on the sound absorption property of the material were investigated. The results show that the sound absorption efficiency at a low frequency increased when decreasing the cell size of PU foam layer. With the increasing of the alternating unit number, the material shows the sound absorption effect in a wider bandwidth of frequency. The BT/NBR-PU foam composites with alternating multilayered structure have an excellent sound absorption property at low frequency due to the organic combination of airflow resistivity, resonance absorption, and interface dissipation.

  20. Application of gas cyclone-liquid jet absorption separator for purification of tail gas containing ammonia.

    PubMed

    Ma, Liang; Zhao, Zhi-Huang; Peng, Lv; Yang, Xue-Jing; Fu, Peng-Bo; Liu, Yi; Huang, Yuan

    2018-05-31

    In this experiment, with stainless steel gas cyclone-liquid jet absorption separator as carrier, NH 3 as experimental gas, and water and H 3 PO 4 solution as absorbents, corresponding NH 3 absorption rate change is obtained through the adjustment of experimental parameters, such as NH 3 inlet concentration, inlet velocity of mixed gas, injection flow rate of absorbent, temperature of absorbent, and H 3 PO 4 absorbent concentration. The NH 3 absorption rate decreases with the increase in NH 3 inlet concentration and inlet gas velocity. The NH 3 absorption rate will increase first and then tends to remain unchanged after reaching a certain degree with the increase in liquid injection flow rate and absorbent concentration. The NH 3 absorption rate will increase first and then decrease with the increase in the absorbent temperature. The maximum NH 3 removal efficiencies of water and H 3 PO 4 were 96% and 99%, respectively.

  1. Increasing the applicability of density functional theory. V. X-ray absorption spectra with ionization potential corrected exchange and correlation potentials.

    PubMed

    Verma, Prakash; Bartlett, Rodney J

    2016-07-21

    Core excitation energies are computed with time-dependent density functional theory (TD-DFT) using the ionization energy corrected exchange and correlation potential QTP(0,0). QTP(0,0) provides C, N, and O K-edge spectra to about an electron volt. A mean absolute error (MAE) of 0.77 and a maximum error of 2.6 eV is observed for QTP(0,0) for many small molecules. TD-DFT based on QTP (0,0) is then used to describe the core-excitation spectra of the 22 amino acids. TD-DFT with conventional functionals greatly underestimates core excitation energies, largely due to the significant error in the Kohn-Sham occupied eigenvalues. To the contrary, the ionization energy corrected potential, QTP(0,0), provides excellent approximations (MAE of 0.53 eV) for core ionization energies as eigenvalues of the Kohn-Sham equations. As a consequence, core excitation energies are accurately described with QTP(0,0), as are the core ionization energies important in X-ray photoionization spectra or electron spectroscopy for chemical analysis.

  2. Effect of Feed Gas Flow Rate on CO2 Absorption through Super Hydrophobic Hollow Fiber membrane Contactor

    NASA Astrophysics Data System (ADS)

    Kartohardjono, Sutrasno; Alexander, Kevin; Larasati, Annisa; Sihombing, Ivander Christian

    2018-03-01

    Carbon dioxide is pollutant in natural gas that could reduce the heating value of the natural gas and cause problem in transportation due to corrosive to the pipeline. This study aims to evaluate the effects of feed gas flow rate on CO2 absorption through super hydrophobic hollow fiber contactor. Polyethyleneglycol-300 (PEG-300) solution was used as absorbent in this study, whilst the feed gas used in the experiment was a mixture of 30% CO2 and 70% CH4. There are three super hydrophobic hollow fiber contactors sized 6 cm and 25 cm in diameter and length used in this study, which consists of 1000, 3000 and 5000 fibers, respectively. The super hydrophobic fiber membrane used is polypropylene-based with outer and inner diameter of about 525 and 235 μm, respectively. In the experiments, the feed gas was sent through the shell side of the membrane contactor, whilst the absorbent solution was pumped through the lumen fibers. The experimental results showed that the mass transfer coefficient, flux, absorption efficiency for CO2-N2 system and CO2 loading increased with the feed gas flow rate, but the absorption efficiency for CO2-N2 system decreased. The mass transfer coefficient and the flux, at the same feed gas flow rate, decreased with the number of fibers in the membrane contactor, but the CO2 absorption efficiency and the CO2 loading increased.

  3. Analyzing Water's Optical Absorption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A cooperative agreement between World Precision Instruments (WPI), Inc., and Stennis Space Center has led the UltraPath(TM) device, which provides a more efficient method for analyzing the optical absorption of water samples at sea. UltraPath is a unique, high-performance absorbance spectrophotometer with user-selectable light path lengths. It is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the laboratory or the field. As a low-cost, rugged, and portable system capable of high- sensitivity measurements in widely divergent waters, UltraPath will help scientists examine the role that coastal ocean environments play in the global carbon cycle. UltraPath(TM) is a trademark of World Precision Instruments, Inc. LWCC(TM) is a trademark of World Precision Instruments, Inc.

  4. Enhanced absorption in two-dimensional materials via Fano-resonant photonic crystals

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

    Wang, Wenyi; Klots, Andrey; Bolotin, Kirill I.

    2015-05-04

    The use of two-dimensional (2D) materials in optoelectronics has attracted much attention due to their fascinating optical and electrical properties. 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 near-infrared regimes monolayer MoS{sub 2} 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%more » 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

  5. Ternary Nonfullerene Polymer Solar Cells with 12.16% Efficiency by Introducing One Acceptor with Cascading Energy Level and Complementary Absorption.

    PubMed

    Jiang, Weigang; Yu, Runnan; Liu, Zhiyang; Peng, Ruixiang; Mi, Dongbo; Hong, Ling; Wei, Qiang; Hou, Jianhui; Kuang, Yongbo; Ge, Ziyi

    2018-01-01

    A novel small-molecule acceptor, (2,2'-((5E,5'E)-5,5'-((5,5'-(4,4,9,9-tetrakis(5-hexylthiophen-2-yl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis(4-(2-ethylhexyl)thiophene-5,2-diyl))bis(methanylylidene)) bis(3-hexyl-4-oxothiazolidine-5,2-diylidene))dimalononitrile (ITCN), end-capped with electron-deficient 2-(3-hexyl-4-oxothiazolidin-2-ylidene)malononitrile groups, is designed, synthesized, and used as the third component in fullerene-free ternary polymer solar cells (PSCs). The cascaded energy-level structure enabled by the newly designed acceptor is beneficial to the carrier transport and separation. Meanwhile, the three materials show a complementary absorption in the visible region, resulting in efficient light harvesting. Hence, the PBDB-T:ITCN:IT-M ternary PSCs possess a high short-circuit current density (J sc ) under an optimal weight ratio of donors and acceptors. Moreover, the open-circuit voltage (V oc ) of the ternary PSCs is enhanced with an increase of the third acceptor ITCN content, which is attributed to the higher lowest unoccupied molecular orbital energy level of ITCN than that of IT-M, thus exhibits a higher V oc in PBDB-T:ITCN binary system. Ultimately, the ternary PSCs achieve a power conversion efficiency of 12.16%, which is higher than the PBDB-T:ITM-based PSCs (10.89%) and PBDB-T:ITCN-based ones (2.21%). This work provides an effective strategy to improve the photovoltaic performance of PSCs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Efficiency enhancement of liquid crystal projection displays using light recycle technology

    NASA Technical Reports Server (NTRS)

    Wang, Y.

    2002-01-01

    A new technology developed at JPL using low absorption color filters with polarization and color recycle system, is able to enhance efficiency of a single panel liquid crytal display (LCD) projector to the same efficiency of a 3 panel LCD projector.

  7. Molecular modification of coumarin dyes for more efficient dye sensitized solar cells

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

    Sanchez-de-Armas, Rocio; San-Miguel, Miguel A.; Oviedo, Jaime

    2012-05-21

    In this work, new coumarin based dyes for dye sensitized solar cells (DSSC) have been designed by introducing several substituent groups in different positions of the NKX-2311 structure. Two types of substitutions have been considered: the introduction of three electron-donating groups (-OH, -NH{sub 2}, and -OCH{sub 3}) and two different substituents with steric effect: -CH{sub 2}-CH{sub 2}-CH{sub 2}- and -CH{sub 2}-HC=CH-. The electronic absorption spectra (position and width of the first band and absorption threshold) and the position of the LUMO level related to the conduction band have been used as theoretical criteria to evaluate the efficiency of the newmore » dyes. The introduction of a -NH{sub 2} group produces a redshift of the absorption maximum position and the absorption threshold, which could improve the cell efficiency. In contrast, the introduction of -CH{sub 2}-CH{sub 2}-CH{sub 2}- does not modify significantly the electronic structure of NKX-2311, but it might prevent aggregation. Finally, -CH{sub 2}-HC=CH- produces important changes both in the electronic spectrum and in the electronic structure of the dye, and it would be expected as an improvement of cell efficiency for these dyes.« less

  8. Ionic liquids based microwave-assisted extraction of lichen compounds with quantitative spectrophotodensitometry analysis.

    PubMed

    Bonny, Sarah; Paquin, Ludovic; Carrié, Daniel; Boustie, Joël; Tomasi, Sophie

    2011-11-30

    Ionic liquids based extraction method has been applied to the effective extraction of norstictic acid, a common depsidone isolated from Pertusaria pseudocorallina, a crustose lichen. Five 1-alkyl-3-methylimidazolium ionic liquids (ILs) differing in composition of alkyl chain and anion were investigated for extraction efficiency. The extraction amount of norstictic acid was determined after recovery on HPTLC with a spectrophotodensitometer. The proposed approaches (IL-MAE and IL-heat extraction (IL-HE)) have been evaluated in comparison with usual solvents such as tetrahydrofuran in heat-reflux extraction and microwave-assisted extraction (MAE). The results indicated that both the characteristics of the alkyl chain and anion influenced the extraction of polyphenolic compounds. The sulfate-based ILs [C(1)mim][MSO(4)] and [C(2)mim][ESO(4)] presented the best extraction efficiency of norstictic acid. The reduction of the extraction times between HE and MAE (2 h-5 min) and a non-negligible ratio of norstictic acid in total extract (28%) supports the suitability of the proposed method. This approach was successfully applied to obtain additional compounds from other crustose lichens (Pertusaria amara and Ochrolechia parella). Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Hierarchical Graphene Foam for Efficient Omnidirectional Solar-Thermal Energy Conversion.

    PubMed

    Ren, Huaying; Tang, Miao; Guan, Baolu; Wang, Kexin; Yang, Jiawei; Wang, Feifan; Wang, Mingzhan; Shan, Jingyuan; Chen, Zhaolong; Wei, Di; Peng, Hailin; Liu, Zhongfan

    2017-10-01

    Efficient solar-thermal energy conversion is essential for the harvesting and transformation of abundant solar energy, leading to the exploration and design of efficient solar-thermal materials. Carbon-based materials, especially graphene, have the advantages of broadband absorption and excellent photothermal properties, and hold promise for solar-thermal energy conversion. However, to date, graphene-based solar-thermal materials with superior omnidirectional light harvesting performances remain elusive. Herein, hierarchical graphene foam (h-G foam) with continuous porosity grown via plasma-enhanced chemical vapor deposition is reported, showing dramatic enhancement of broadband and omnidirectional absorption of sunlight, which thereby can enable a considerable elevation of temperature. Used as a heating material, the external solar-thermal energy conversion efficiency of the h-G foam impressively reaches up to ≈93.4%, and the solar-vapor conversion efficiency exceeds 90% for seawater desalination with high endurance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Effects of 1,25-dihydroxycholecalciferol on 47calcium absorption in post-menopausal osteoporosis.

    PubMed

    Caniggia, A; Vattimo, A

    1979-07-01

    Measurement of 47Calcium absorption was performed on eleven women with post-menopausal osteoporosis. The study was repeated after 10 days treatment with 1 microgram daily of 1,25(OH)2D3. These patients showed a statistically significant improvement of fractional calcium absorption that was inversely correlated to the basal values. The prompt improvement of the intestinal calcium transport in post-menopausal osteoporotic women, a few days after the administration of physiological doses of 1,25(OH)2D3, suggests that these patients synthesize inappropriately small amounts of 1,25(OH)2D3 because of their oestrogen deficiency. This could be an important pathogenetic factor in post-menopausal osteoporosis, as the efficiency of the adaptation of calcium absorption to low calcium intakes is dependent on 1,25(OH)2D3.

  11. Advancement of Double Effect Absorption Cycle by Input of Low Temperature Waste Heat

    NASA Astrophysics Data System (ADS)

    Kojima, Hiroshi; Edera, Masaru; Nakamura, Makoto; Oka, Masahiro; Akisawa, Atsushi; Kashiwagi, Takao

    Energy conservation is becoming important for global environmental protection. New simple techniques of more efficient1y using the waste heat of gas co-generation systems for refrigerationare required. In first report, a new method of using the low temperature waste heat for refrigeration was proposed, and the basic characteristics of the promising methods of recovering waste heat were c1arified. In this report, the more detailed simulation model of the series flow type double effect absorption refrigerator with auxiliary heat exchanger was constructed and the static characteristics were investigated. Then experiments on this advanced absorption refrigerator were carried out, and the results of the calculation and experiments were compared and discussed. Moreover, the betterment of the simulation model of this advanced absorption refrigerator was carried out.

  12. Towards an improved understanding of processes controlling absorption efficiency and biomagnification of organic chemicals by fish.

    PubMed

    Xiao, Ruiyang; Arnot, Jon A; MacLeod, Matthew

    2015-11-01

    Dietary exposure is considered the dominant pathway for fish exposed to persistent, hydrophobic chemicals in the environment. Here we present a dynamic, fugacity-based three-compartment bioaccumulation model that describes the fish body as one compartment and the gastrointestinal tract (GIT) as two compartments. The model simulates uptake from the GIT by passive diffusion and micelle-mediated diffusion, and chemical degradation in the fish and the GIT compartments. We applied the model to a consistent measured dietary uptake and depuration dataset for rainbow trout (n=215) that is comprised of chlorinated benzenes, biphenyls, dioxins, diphenyl ethers, and polycyclic aromatic hydrocarbons (PAHs). Model performance relative to the measured data is statistically similar regardless of whether micelle-mediated diffusion is included; however, there are considerable uncertainties in modeling this process. When degradation in the GIT is assumed to be negligible, modeled chemical elimination rates are similar to measured rates; however, predicted concentrations of the PAHs are consistently higher than measurements by up to a factor of 20. Introducing a kinetic limit on chemical transport from the fish compartment to the GIT and increasing the rate constant for degradation of PAHs in tissues of the liver and/or GIT are required to achieve good agreement between the modelled and measured concentrations for PAHs. Our results indicate that the apparent low absorption efficiency of PAHs relative to the chemicals with similar hydrophobicity is attributable to biotransformation in the liver and/or the GIT. Our results provide process-level insights about controls on the extent of bioaccumulation of chemicals. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Probiotics and Other Key Determinants of Dietary Oxalate Absorption1

    PubMed Central

    Liebman, Michael; Al-Wahsh, Ismail A.

    2011-01-01

    Oxalate is a common component of many foods of plant origin, including nuts, fruits, vegetables, grains, and legumes, and is typically present as a salt of oxalic acid. Because virtually all absorbed oxalic acid is excreted in the urine and hyperoxaluria is known to be a considerable risk factor for urolithiasis, it is important to understand the factors that have the potential to alter the efficiency of oxalate absorption. Oxalate bioavailability, a term that has been used to refer to that portion of food-derived oxalate that is absorbed from the gastrointestinal tract (GIT), is estimated to range from 2 to 15% for different foods. Oxalate bioavailability appears to be decreased by concomitant food ingestion due to interactions between oxalate and coingested food components that likely result in less oxalic acid remaining in a soluble form. There is a lack of consensus in the literature as to whether efficiency of oxalate absorption is dependent on the proportion of total dietary oxalate that is in a soluble form. However, studies that directly compared foods of varying soluble oxalate contents have generally supported the proposition that the amount of soluble oxalate in food is an important determinant of oxalate bioavailability. Oxalate degradation by oxalate-degrading bacteria within the GIT is another key factor that could affect oxalate absorption and degree of oxaluria. Studies that have assessed the efficacy of oral ingestion of probiotics that provide bacteria with oxalate-degrading capacity have led to promising but generally mixed results, and this remains a fertile area for future studies. PMID:22332057

  14. Cavity ring-down spectroscopy (CRDS) system for measuring atmospheric mercury using differential absorption

    NASA Astrophysics Data System (ADS)

    Pierce, A.; Obrist, D.; Moosmuller, H.; Moore, C.

    2012-04-01

    Atmospheric elemental mercury (Hg0) is a globally pervasive element that can be transported and deposited to remote ecosystems where it poses — particularly in its methylated form — harm to many organisms including humans. Current techniques for measurement of atmospheric Hg0 require several liters of sample air and several minutes for each analysis. Fast-response (i.e., 1 second or faster) measurements would improve our ability to understand and track chemical cycling of mercury in the atmosphere, including high frequency Hg0 fluctuations, sources and sinks, and chemical transformation processes. We present theory, design, challenges, and current results of our new prototype sensor based on cavity ring-down spectroscopy (CRDS) for fast-response measurement of Hg0 mass concentrations. CRDS is a direct absorption technique that implements path-lengths of multiple kilometers in a compact absorption cell using high-reflectivity mirrors, thereby improving sensitivity and reducing sample volume compared to conventional absorption spectroscopy. Our sensor includes a frequency-doubled, dye-laser emitting laser pulses tunable from 215 to 280 nm, pumped by a Q-switched, frequency tripled Nd:YAG laser with a pulse repetition rate of 50 Hz. We present how we successfully perform automated wavelength locking and stabilization of the laser to the peak Hg0 absorption line at 253.65 nm using an external isotopically-enriched mercury (202Hg0) cell. An emphasis of this presentation will be on the implementation of differential absorption measurement whereby measurements are alternated between the peak Hg0 absorption wavelength and a nearby wavelength "off" the absorption line. This can be achieved using a piezo electric tuning element that allows for pulse-by-pulse tuning and detuning of the laser "online" and "offline" of the Hg absorption line, and thereby allows for continuous correction of baseline extinction losses. Unexpected challenges with this approach included

  15. Absorption spectrum of a two-level system subjected to a periodic pulse sequence

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

    Fotso, H. F.; Dobrovitski, V. V.

    We investigate how the quantum control of a two-level system (TLS) coupled to photons can modify and tune the TLS’s photon absorption spectrum. Tuning and controlling the emission and the absorption is of much interest e.g. for the development of efficient interfaces between stationary and flying qubits in modern architectures for quantum computation and quantum communication. We consider the periodic pulse control, where the TLS is subjected to a periodic sequence of the near-resonant Rabi driving pulses, each pulse implementing a 180° rotation. For small inter-pulse delays, the absorption spectrum features a pronounced peak of stimulated emission at the pulsemore » frequency, as well as equidistant satellite peaks with smaller spectral weights. As long as the detuning between the carrier frequency of the driving and the TLS transition frequency remains moderate, this spectral shape shows little change. Therefore, the quantum control allows shifting the absorption peak to a desired position, and locks the absorption peak to the carrier frequency of the driving pulses. Detailed description of the spectrum, and its evolution as a function time, the inter-pulse spacing and the detuning, is presented.« less

  16. Absorption spectrum of a two-level system subjected to a periodic pulse sequence

    DOE PAGES

    Fotso, H. F.; Dobrovitski, V. V.

    2017-06-01

    We investigate how the quantum control of a two-level system (TLS) coupled to photons can modify and tune the TLS’s photon absorption spectrum. Tuning and controlling the emission and the absorption is of much interest e.g. for the development of efficient interfaces between stationary and flying qubits in modern architectures for quantum computation and quantum communication. We consider the periodic pulse control, where the TLS is subjected to a periodic sequence of the near-resonant Rabi driving pulses, each pulse implementing a 180° rotation. For small inter-pulse delays, the absorption spectrum features a pronounced peak of stimulated emission at the pulsemore » frequency, as well as equidistant satellite peaks with smaller spectral weights. As long as the detuning between the carrier frequency of the driving and the TLS transition frequency remains moderate, this spectral shape shows little change. Therefore, the quantum control allows shifting the absorption peak to a desired position, and locks the absorption peak to the carrier frequency of the driving pulses. Detailed description of the spectrum, and its evolution as a function time, the inter-pulse spacing and the detuning, is presented.« less

  17. Origin of improved scintillation efficiency in (Lu,Gd)3(Ga,Al)5O12:Ce multicomponent garnets: An X-ray absorption near edge spectroscopy study

    NASA Astrophysics Data System (ADS)

    Wu, Yuntao; Luo, Jialiang; Nikl, Martin; Ren, Guohao

    2014-01-01

    In the recent successful improvement of scintillation efficiency in Lu3Al5O12:Ce driven by Ga3+ and Gd3+ admixture, the "band-gap engineering" and energy level positioning have been considered the valid strategies so far. This study revealed that this improvement was also associated with the cerium valence instability along with the changes of chemical composition. By utilizing X-ray absorption near edge spectroscopy technique, tuning the Ce3+/Ce4+ ratio by Ga3+ admixture was evidenced, while it was kept nearly stable with the Gd3+ admixture. Ce valence instability and Ce3+/Ce4+ ratio in multicomponent garnets can be driven by the energy separation between 4f ground state of Ce3+ and Fermi level.

  18. UV-responsive nano-sponge for oil absorption and desorption

    PubMed Central

    Kim, Do Hyun; Jung, Min Chan; Cho, So-Hye; Kim, Sang Hoon; Kim, Ho-Young; Lee, Heon Ju; Oh, Kyu Hwan; Moon, Myoung-Woon

    2015-01-01

    Controlled surface wettability for oil has been intensively studied to remove industrial oil waste or oil spill pollution from seas or rivers. In particular, external stimuli-induced special wetting materials, such as photo-responsive TiO2, have attracted considerable attention for oil-water separation. In this study, a novel method is reported to fabricate a nano-sponge which is composed of hydrophobic hydrocarbon and hydrophilic TiO2 nanoparticles for oil absorption or desorption that are responsive to UV irradiation. The hydrocarbon in the nano-sponge could selectively absorb oil from water, whereas the absorbed oil is released into the water by TiO2 in response to UV irradiation. The nano-sponge functionalized porous polydimethylsiloxane released more than 98% of the absorbed crude oil with UV irradiation and air-bubbling. It could be continuously reused while maintaining a high absorption capacity and desorption efficiency without incurring secondary air or water pollution. This smart oil absorption/desorption methodology with excellent selectivity and recyclability with almost perfect removal of absorbed oil can be applied for oil-water separation, oil spill cleanup and reuse of spilled oil. PMID:26260470

  19. [Construction and application of an onboard absorption analyzer device for CDOM].

    PubMed

    Lin, Jun-Fang; Sun, Zhao-Hua; Cao, Wen-Xi; Hu, Shui-Bo; Xu, Zhan-Tang

    2013-04-01

    Colored dissolved organic matter (CDOM) plays an important role in marine ecosystems. In order to solve the current problems in measurement of CDOM absorption, an automated onboard analyzer based on liquid core waveguides (Teflon AF LWCC/LCW) was constructed. This analyzer has remarkable characteristics including adjusted optical pathlength, wide measurement range, and high sensitivity. The model of filtration and injection can implement the function of automated filtration, sample injection, and LWCC cleaning. The LabVIEW software platform can efficiently control the running state of the analyzer and acquire real time data including light absorption spectra, GPS data, and CTW data. By the comparison experiments and shipboard measurements, it was proved that the analyzer was reliable and robust.

  20. Fractal-Like Materials Design with Optimized Radiative Properties for High-Efficiency Solar Energy Conversion

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

    Ho, Clifford K.; Ortega, Jesus D.; Christian, Joshua Mark

    Novel designs to increase light trapping and thermal efficiency of concentrating solar receivers at multiple length scales have been conceived, designed, and tested. The fractal-like geometries and features are introduced at both macro (meters) and meso (millimeters to centimeters) scales. Advantages include increased solar absorptance, reduced thermal emittance, and increased thermal efficiency. Radial and linear structures at the meso (tube shape and geometry) and macro (total receiver geometry and configuration) scales redirect reflected solar radiation toward the interior of the receiver for increased absorptance. Hotter regions within the interior of the receiver can reduce thermal emittance due to reduced localmore » view factors to the environment, and higher concentration ratios can be employed with similar surface irradiances to reduce the effective optical aperture, footprint, and thermal losses. Coupled optical/fluid/thermal models have been developed to evaluate the performance of these designs relative to conventional designs. Modeling results showed that fractal-like structures and geometries can increase the effective solar absorptance by 5 – 20% and the thermal efficiency by several percentage points at both the meso and macro scales, depending on factors such as intrinsic absorptance. Meso-scale prototypes were fabricated using additive manufacturing techniques, and a macro-scale bladed receiver design was fabricated using Inconel 625 tubes. On-sun tests were performed using the solar furnace and solar tower at the National Solar Thermal Test facility. The test results demonstrated enhanced solar absorptance and thermal efficiency of the fractal-like designs.« less

  1. Cascade Reverse Osmosis Air Conditioning System: Cascade Reverse Osmosis and the Absorption Osmosis Cycle

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

    None

    BEETIT Project: Battelle is developing a new air conditioning system that uses a cascade reverse osmosis (RO)-based absorption cycle. Analyses show that this new cycle can be as much as 60% more efficient than vapor compression, which is used in 90% of air conditioners. Traditional vapor-compression systems use polluting liquids for a cooling effect. Absorption cycles use benign refrigerants such as water, which is absorbed in a salt solution and pumped as liquid—replacing compression of vapor. The refrigerant is subsequently separated from absorbing salt using heat for re-use in the cooling cycle. Battelle is replacing thermal separation of refrigerant withmore » a more efficient reverse osmosis process. Research has shown that the cycle is possible, but further investment will be needed to reduce the number of cascade reverse osmosis stages and therefore cost.« less

  2. Effect of in-material losses on terahertz absorption, transmission, and reflection in photonic crystals made of polar dielectrics

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

    Serebryannikov, Andriy E., E-mail: andser@amu.edu.pl; Nanotechnology Research Center—NANOTAM, Bilkent University, 06800 Ankara; Nojima, S.

    2015-10-07

    The effect of the material absorption factor on terahertz absorption (A), transmittance (T), and reflectance (R) for slabs of PhC that comprise rods made of GaAs, a polar dielectric, is studied. The main goal was to illustrate how critical a choice of the absorption factor for simulations is and to indicate the importance of the possible modification of the absorption ability by using either active or lossy impurities. The spectra of A, T, and R are strongly sensitive to the location of the polaritonic gap with respect to the photonic pass and stop bands connected with periodicity that enables themore » efficient combination of the effects of material and structural parameters. It will be shown that the spectra can strongly depend on the utilized value of the material absorption factor. In particular, both narrow and wide absorption bands may appear owing to a variation of the material parameters with a frequency in the vicinity of the polaritonic gap. The latter are often achieved at wideband suppression of transmission, so that an ultra-wide stop band can appear as a result of adjustment of the stop bands having different origin. The results obtained at simultaneous variation of the absorption factor and frequency, and angle of incidence and frequency, indicate the possibility of the existence of wide ranges of tolerance, in which the basic features do remain. This allows for mitigating the accuracy requirements for the absorption factor in simulations and promises the efficient absorption of nonmonochromatic waves and beams with a wide angular spectrum. Suppression of narrowband effects in transmission is demonstrated at rather large values of the absorption factor, when they appear due to either the defect modes related to structural defects or dispersion inspired variations of the material parameters in the vicinity of the polaritonic gap. Comparison with auxiliary structures helps one to detect the common features and differences of homogeneous slabs and

  3. Facile fabrication of high-efficiency near-infrared absorption film with tungsten bronze nanoparticle dense layer

    NASA Astrophysics Data System (ADS)

    Lee, Seong Yun; Kim, Jae Young; Lee, Jun Young; Song, Ho Jun; Lee, Sangkug; Choi, Kyung Ho; Shin, Gyojic

    2014-06-01

    An excellent transparent film with effective absorption property in near-infrared (NIR) region based on cesium-doped tungsten oxide nanoparticles was fabricated using a facile double layer coating method via the theoretical considerations. The optical performance was evaluated; the double layer-coated film exhibited 10% transmittance at 1,000 nm in the NIR region and over 80% transmittance at 550 nm in the visible region. To optimize the selectivity, the optical spectrum of this film was correlated with a theoretical model by combining the contributions of the Mie-Gans absorption-based localized surface plasmon resonance and reflections by the interfaces of the heterogeneous layers and the nanoparticles in the film. Through comparison of the composite and double layer coating method, the difference of the nanoscale distances between nanoparticles in each layer was significantly revealed. It is worth noting that the nanodistance between the nanoparticles decreased in the double layer film, which enhanced the optical properties of the film, yielding a haze value of 1% or less without any additional process. These results are very attractive for the nanocomposite coating process, which would lead to industrial fields of NIR shielding and thermo-medical applications.

  4. Efficient light absorption by plasmonic metallic nanostructures in photovoltaic application

    NASA Astrophysics Data System (ADS)

    Roy, Rhombik; Datta, Debasish

    2018-04-01

    This article reports the way to trap light efficiently inside a tri-layered Cu(Zn,Sn)S2 (CZTS) and Zinc Oxide (ZnO) based solar cell module using Ag nanoparticles as light concentrators by virtue of their plasmonic property. The passage of E. M. radiation within the cell has been simulated using finite difference time domain (FDTD) method.

  5. Porous Graphene Microflowers for High-Performance Microwave Absorption

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Xi, Jiabin; Zhou, Erzhen; Peng, Li; Chen, Zichen; Gao, Chao

    2018-06-01

    Graphene has shown great potential in microwave absorption (MA) owing to its high surface area, low density, tunable electrical conductivity and good chemical stability. To fully realize graphene's MA ability, the microstructure of graphene should be carefully addressed. Here we prepared graphene microflowers (Gmfs) with highly porous structure for high-performance MA filler material. The efficient absorption bandwidth (reflection loss ≤ -10 dB) reaches 5.59 GHz and the minimum reflection loss is up to -42.9 dB, showing significant increment compared with stacked graphene. Such performance is higher than most graphene-based materials in the literature. Besides, the low filling content (10 wt%) and low density (40-50 mg cm-3) are beneficial for the practical applications. Without compounding with magnetic materials or conductive polymers, Gmfs show outstanding MA performance with the aid of rational microstructure design. Furthermore, Gmfs exhibit advantages in facile processibility and large-scale production compared with other porous graphene materials including aerogels and foams.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  7. Preparation and high-performance microwave absorption of hierarchical dendrite-like Co superstructures self-assembly of nanoflakes

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Wang, Lirui; Yang, Pingan; Fu, Jie

    2017-12-01

    Dendritic-like Co superstructures based on the self-assembly of nanoflakes that could efficiently suppress the eddy current were successfully synthesized via a facile, rapid, and energy-saving chemical reduction method. Since crystal structure, size, and special geometrical morphology, magnetism have a vital influence on microwave absorption properties, the as-obtained products were characterized by x-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, and vector network analysis. The prepared dendritic Co possesses abundant secondary branches that extend to the 3D space. Their dimensions, spacing, sheet-like blocks, and high-ordering microstructures all contribute to the penetration, scattering, and attenuation of EM waves. The composites present attractive microwave absorption performances in the X band, as well as in the whole S band (2-4 GHz). This work investigates the mechanism of absorption for the as-obtained Co, offers a promising strategy for the fabrication of hierarchical Co microstructure assemblies by multi-leaf flakes and introduces the application of dendritic-like Co as a highly efficient absorber in the S band and X band.

  8. Constructing organic D-A-π-A-featured sensitizers with a quinoxaline unit for high-efficiency solar cells: the effect of an auxiliary acceptor on the absorption and the energy level alignment.

    PubMed

    Pei, Kai; Wu, Yongzhen; Wu, Wenjun; Zhang, Qiong; Chen, Baoqin; Tian, He; Zhu, Weihong

    2012-06-25

    Four organic D-A-π-A-featured sensitizers (TQ1, TQ2, IQ1, and IQ2) have been studied for high-efficiency dye-sensitized solar cells (DSSCs). We employed an indoline or a triphenylamine unit as the donor, cyanoacetic acid as the acceptor/anchor, and a thiophene moiety as the conjugation bridge. Additionally, an electron-withdrawing quinoxaline unit was incorporated between the donor and the π-conjugation unit. These sensitizers show an additional absorption band covering the broad visible range in solution. The contribution from the incorporated quinoxaline was investigated theoretically by using DFT and time-dependent DFT. The incorporated low-band-gap quinoxaline unit as an auxiliary acceptor has several merits, such as decreasing the band gap, optimizing the energy levels, and realizing a facile structural modification on several positions in the quinoxaline unit. As demonstrated, the observed additional absorption band is favorable to the photon-to-electron conversion because it corresponds to the efficient electron transitions to the LUMO orbital. Electrochemical impedance spectroscopy (EIS) Bode plots reveal that the replacement of a methoxy group with an octyloxy group can increase the injection electron lifetime by a factor of 2.4. IQ2 and TQ2 can perform well without any co-adsorbent, successfully suppress the charge recombination from TiO(2) conduction band to I(3)(-) in the electrolyte, and enhance the electron lifetime, resulting in a decreased dark current and enhanced open circuit voltage (V(oc)) values. By using a liquid electrolyte, DSSCs based on dye IQ2 exhibited a broad incident photon-to-current conversion efficiency (IPCE) action spectrum and high efficiency (η=8.50 %) with a short circuit current density (J(sc)) of 15.65 mA cm(-2), a V(oc) value of 776 mV, a fill factor (FF) of 0.70 under AM 1.5 illumination (100 mW cm(-2)). Moreover, the overall efficiency remained at 97% of the initial value after 1000 h of visible

  9. The effect of a periodic absorptive strip arrangement on an interior sound field in a room.

    PubMed

    Park, Joo-Bae; Grosh, Karl; Kim, Yang-Hann

    2005-02-01

    In this paper we study the effect of periodically arranged sound absorptive strips on the mean acoustic potential energy density distribution of a room. The strips are assumed to be attached on the room's surface of interest. In order to determine their effect, the mean acoustic potential energy density variation is evaluated as the function of a ratio of the strip's arrangement period to wavelength. The evaluation demonstrates that the mean acoustic potential energy density tends to converge. In addition, a comparison with a case in which absorptive materials completely cover the selected absorptive plane shows that a periodic arrangement that uses only half of the absorptive material can be more efficient than a total covering, unless the frequency of interest does not coincide with the room's resonant frequencies. Consequently, the results prove that the ratio of the arrangement period to the wavelength plays an important role in the effectiveness of a periodic absorptive strip arrangement to minimize a room's mean acoustic potential energy density.

  10. Optical Absorption in Liquid Semiconductors

    NASA Astrophysics Data System (ADS)

    Bell, Florian Gene

    An infrared absorption cell has been developed which is suitable for high temperature liquids which have absorptions in the range .1-10('3) cm('-1). The cell is constructed by clamping a gasket between two flat optical windows. This unique design allows the use of any optical windows chemically compatible with the liquid. The long -wavelength limit of the measurements is therefore limited only by the choice of the optical windows. The thickness of the cell can easily be set during assembly, and can be varied from 50 (mu)m to .5 cm. Measurements of the optical absorption edge were performed on the liquid alloy Se(,1-x)Tl(,x) for x = 0, .001, .002, .003, .005, .007, and .009, from the melting point up to 475(DEGREES)C. The absorption was found to be exponential in the photon energy over the experimental range from 0.3 eV to 1.2 eV. The absorption increased linearly with concentration according to the empirical relation (alpha)(,T)(h(nu)) = (alpha)(,1) + (alpha)(,2)x, and the absorption (alpha)(,1) was interpreted as the absorption in the absence of T1. (alpha)(,1) also agreed with the measured absorption in 100% Se at corresponding temperatures and energies. The excess absorption defined by (DELTA)(alpha) = (alpha)(,T)(h(nu))-(alpha)(,1) was interpreted as the absorption associated with Tl and was found to be thermally activated with an activation energy E(,t) = 0.5 eV. The exponential edge is explained as absorption on atoms immersed in strong electric fields surrounding ions. The strong fields give rise to an absorption tail similar to the Franz-Keldysh effect. A simple calculation is performed which is based on the Dow-Redfield theory of absorption in an electric field with excitonic effects included. The excess absorption at low photon energies is proportional to the square of the concentration of ions, which are proposed to exist in the liquid according to the relation C(,i) (PROPORTIONAL) x(' 1/2)(.)e('-E)t('/kT), which is the origin of the thermal activation

  11. The ultimate efficiency of photosensitive systems

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. M.; Byvik, C. E.; Smith, B. T.

    1981-01-01

    These systems have in common two important but not independent features: they can produce a storable fuel, and they are sensitive only to radiant energy with a characteristic absorption spectrum. General analyses of the conversion efficiencies were made using the operational characteristics of each particular system. An efficiency analysis of a generalized system consisting of a blackbody source, a radiant energy converter having a threshold energy and operating temperature, and a reservoir is reported. This analysis is based upon the first and second laws of thermodynamics, and leads to a determination of the limiting or ultimate efficiency for an energy conversion system having a characteristic threshold.

  12. Resonant Absorption in GaAs-Based Nanowires by Means of Photo-Acoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Petronijevic, E.; Leahu, G.; Belardini, A.; Centini, M.; Li Voti, R.; Hakkarainen, T.; Koivusalo, E.; Guina, M.; Sibilia, C.

    2018-03-01

    Semiconductor nanowires made of high refractive index materials can couple the incoming light to specific waveguide modes that offer resonant absorption enhancement under the bandgap wavelength, essential for light harvesting, lasing and detection applications. Moreover, the non-trivial ellipticity of such modes can offer near field interactions with chiral molecules, governed by near chiral field. These modes are therefore very important to detect. Here, we present the photo-acoustic spectroscopy as a low-cost, reliable, sensitive and scattering-free tool to measure the spectral position and absorption efficiency of these modes. The investigated samples are hexagonal nanowires with GaAs core; the fabrication by means of lithography-free molecular beam epitaxy provides controllable and uniform dimensions that allow for the excitation of the fundamental resonant mode around 800 nm. We show that the modulation frequency increase leads to the discrimination of the resonant mode absorption from the overall absorption of the substrate. As the experimental data are in great agreement with numerical simulations, the design can be optimized and followed by photo-acoustic characterization for a specific application.

  13. Characterization of black carbon in an urban-rural fringe area of Beijing.

    PubMed

    Ji, Dongsheng; Li, Liang; Pang, Bo; Xue, Peng; Wang, Lili; Wu, Yunfei; Zhang, Hongliang; Wang, Yuesi

    2017-04-01

    Measuring black carbon (BC) is critical to understand the impact of combustion aerosols on air quality and climate change. In this study, BC was measured in 2014 at a unique community formed with rapid economic development and urbanization in an urban-rural fringe area of Beijing. Hourly BC concentrations were 0.1-33.5 μg/m 3 with the annual average of 4.4 ± 3.7 μg/m 3 . BC concentrations had clear diurnal, weekly, and seasonal variations, and were closely related with atmospheric visibility. The absorption coefficient of aerosols increased while its contribution to extinction coefficient decreased with the enhancement of PM 2.5 concentration. The high mass absorption efficiency (MAE) of EC was attributed to a combination of coal combustion, vehicular emission and rapidly coating by water-soluble ions and organic carbon (OC). BC concentrations followed a typical lognormal pattern, with over 88% samples in 0.1-10.0 μg/m 3 . Low BC levels were mostly bounded up with winds from north and northwest. Coal combustion and biomass burning were closely associated with severe haze pollution events. Firework discharge had significant UV absorption contribution. During the Asia-Pacific Economic Cooperation (APEC) forum in November 2014, air quality obviously improved due to various control strategies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Intestinal absorption of water-soluble vitamins in health and disease.

    PubMed

    Said, Hamid M

    2011-08-01

    Our knowledge of the mechanisms and regulation of intestinal absorption of water-soluble vitamins under normal physiological conditions, and of the factors/conditions that affect and interfere with theses processes has been significantly expanded in recent years as a result of the availability of a host of valuable molecular/cellular tools. Although structurally and functionally unrelated, the water-soluble vitamins share the feature of being essential for normal cellular functions, growth and development, and that their deficiency leads to a variety of clinical abnormalities that range from anaemia to growth retardation and neurological disorders. Humans cannot synthesize water-soluble vitamins (with the exception of some endogenous synthesis of niacin) and must obtain these micronutrients from exogenous sources. Thus body homoeostasis of these micronutrients depends on their normal absorption in the intestine. Interference with absorption, which occurs in a variety of conditions (e.g. congenital defects in the digestive or absorptive system, intestinal disease/resection, drug interaction and chronic alcohol use), leads to the development of deficiency (and sub-optimal status) and results in clinical abnormalities. It is well established now that intestinal absorption of the water-soluble vitamins ascorbate, biotin, folate, niacin, pantothenic acid, pyridoxine, riboflavin and thiamin is via specific carrier-mediated processes. These processes are regulated by a variety of factors and conditions, and the regulation involves transcriptional and/or post-transcriptional mechanisms. Also well recognized now is the fact that the large intestine possesses specific and efficient uptake systems to absorb a number of water-soluble vitamins that are synthesized by the normal microflora. This source may contribute to total body vitamin nutrition, and especially towards the cellular nutrition and health of the local colonocytes. The present review aims to outline our current

  15. Intestinal absorption of water-soluble vitamins in health and disease

    PubMed Central

    Said, Hamid M.

    2014-01-01

    Our knowledge of the mechanisms and regulation of intestinal absorption of water-soluble vitamins under normal physiological conditions, and of the factors/conditions that affect and interfere with theses processes has been significantly expanded in recent years as a result of the availability of a host of valuable molecular/cellular tools. Although structurally and functionally unrelated, the water-soluble vitamins share the feature of being essential for normal cellular functions, growth and development, and that their deficiency leads to a variety of clinical abnormalities that range from anaemia to growth retardation and neurological disorders. Humans cannot synthesize water-soluble vitamins (with the exception of some endogenous synthesis of niacin) and must obtain these micronutrients from exogenous sources. Thus body homoeostasis of these micronutrients depends on their normal absorption in the intestine. Interference with absorption, which occurs in a variety of conditions (e.g. congenital defects in the digestive or absorptive system, intestinal disease/resection, drug interaction and chronic alcohol use), leads to the development of deficiency (and sub-optimal status) and results in clinical abnormalities. It is well established now that intestinal absorption of the water-soluble vitamins ascorbate, biotin, folate, niacin, pantothenic acid, pyridoxine, riboflavin and thiamin is via specific carrier-mediated processes. These processes are regulated by a variety of factors and conditions, and the regulation involves transcriptional and/or post-transcriptional mechanisms. Also well recognized now is the fact that the large intestine possesses specific and efficient uptake systems to absorb a number of water-soluble vitamins that are synthesized by the normal microflora. This source may contribute to total body vitamin nutrition, and especially towards the cellular nutrition and health of the local colonocytes. The present review aims to outline our current

  16. The enhancement of 21.2%-power conversion efficiency in polymer photovoltaic cells by using mixed Au nanoparticles with a wide absorption spectrum of 400 nm-1000 nm

    NASA Astrophysics Data System (ADS)

    Hao, Jing-Yu; Xu, Ying; Zhang, Yu-Pei; Chen, Shu-Fen; Li, Xing-Ao; Wang, Lian-Hui; Huang, Wei

    2015-04-01

    Au nanoparticles (NPs) mixed with a majority of bone-like, rod, and cube shapes and a minority of irregular spheres, which can generate a wide absorption spectrum of 400 nm-1000 nm and three localized surface plasmon resonance peaks, respectively, at 525, 575, and 775 nm, are introduced into the hole extraction layer poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) to improve optical-to-electrical conversion performances in polymer photovoltaic cells. With the doping concentration of Au NPs optimized, the cell performance is significantly improved: the short-circuit current density and power conversion efficiency of the poly(3-hexylthiophene): [6,6]-phenyl-C60-butyric acid methyl ester cell are increased by 20.54% and 21.2%, reaching 11.15 mA·cm-2 and 4.23%. The variations of optical, electrical, and morphology with the incorporation of Au NPs in the cells are analyzed in detail, and our results demonstrate that the cell performance improvement can be attributed to a synergistic reaction, including: 1) both the localized surface plasmon resonance- and scattering-induced absorption enhancement of the active layer, 2) Au doping-induced hole transport/extraction ability enhancement, and 3) large interface roughness-induced efficient exciton dissociation and hole collection. Project supported by the National Basic Research Program of China (Grant Nos. 2015CB932202 and 2012CB933301), the National Natural Science Foundation of China (Grant Nos. 61274065, 51173081, 61136003, BZ2010043, 51372119, and 51172110), the Science Fund from the Ministry of Education of China (Grant No. IRT1148), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20113223110005), the Priority Academic Program Development of Jiangsu Provincial Higher Education Institutions (Grant No. YX03001), and the National Synergistic Innovation Center for Advanced Materials and the Synergetic Innovation Center for Organic Electronics and

  17. Light absorption properties of brown carbon over the southeastern Tibetan Plateau.

    PubMed

    Zhu, Chong-Shu; Cao, Jun-Ji; Huang, Ru-Jin; Shen, Zhen-Xing; Wang, Qi-Yuan; Zhang, Ning-Ning

    2018-06-01

    We present a study of the light-absorbing properties of water-soluble brown carbon (WS-BrC) and methanol-soluble brown carbon (MeS-BrC) at a remote site (Lulang, 3326m above sea level) in the southeastern Tibetan Plateau during the period 2015-2016. The light absorption coefficients at 365nm (b abs365 ) of WS-BrC and MeS-BrC were the highest during winter and the lowest during monsoon season. MeS-BrC absorbs about 1.5 times higher at 365nm compared to WS-BrC. The absorption at 550nm appears lower compared to that of 365nm for WS-BrC and MeS-BrC, respectively. Higher average value of the absorption Ångström exponent (AAE, 365-550nm) was obtained for MeS-BrC (8.2) than that for WS-BrC (6.9). The values of the mass absorption cross section at 365nm (MAC 365 ) indicated that BrC in winter absorbs UV-visible light more efficiently than in monsoon. The results confirm the importance of BrC in contributing to light-absorbing aerosols in this region. The understanding of the light absorption properties of BrC is of great importance, especially in modeling studies for the climate effects and transport of BrC in the Tibetan Plateau. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. 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 MoS 2 and graphene absorb only ~10% and 2.3% of incoming light, respectively. Here, we experimentally demonstrate the use of Fano-resonantmore » 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.« less

  19. Assessing the Extent of Black Carbon Absorption Enhancements from Field Observations

    NASA Astrophysics Data System (ADS)

    Cappa, C. D.; Zhang, X.; Metcalf, A. R.; Kim, H.; Zhang, Q.; Zimmermann, K.; Bertram, T. H.; Corrigan, A. L.; Russell, L. M.

    2013-12-01

    Black carbon (BC) and brown carbon (BrC) play important roles as short-lived climate forcers (SLCFs) as a result of their short atmospheric lifetimes and ability to absorb solar radiation. The direct impacts of BC on climate depend on just how efficiently a given BC particle absorbs solar radiation, while the impacts of BrC depend on the specific properties of the BrC. The addition of 'coatings' to BC particles can theoretically increase the absorption by a given particle, and this theoretical 'lensing' enhancement has been confirmed through laboratory experiments. However, recent field observations (from the CalNex and CARES studies; Cappa et al. 2012), using a novel thermodenuder-absorption method, have suggested that the actual enhancement for ambient particles is substantially less than theoretically expected. Here, we will discuss results from similar measurements made during two recent field studies, the 2013 DISCOVER-AQ Fresno study and the 2013 SOAS Look Rock study. DISCOVER-AQ took place in Jan/Feb 2013 in Fresno, CA. This region is severely impacted by particulate matter from local and regional residential biomass burning, and thus provides a sharp contrast to the previous CalNex and CARES studies. SOAS took place during June/July 2013 at Look Rock National Park, TN, a relatively remote region strongly impacted by biogenic emissions (predominately isoprene) and located approximately 30 miles away from Knoxville, TN. The difference in absorption for dry, ambient particles will be compared with absorption measured for particles that have been passed through a thermodenuder. Additionally, variations in the mass absorption coefficient, determined from comparison of the measured light absorption and refractory black carbon concentrations, will be examined. The relative contributions of BrC and BC to total absorption at 405 nm, 532 nm and 870 nm will be discussed. The overall measurements suggest a relatively small role for lensing-induced absorption

  20. Enhanced absorption of light by charged nanoparticles.

    PubMed

    Rosenkrantz, Etai; Arnon, Shlomi

    2010-04-15

    We found that various charged nanoparticles (NPs) can raise the attenuation of electromagnetic (EM) radiation over 30 times more efficiently during resonance in comparison to equivalent noncharged particles for a given set of parameters. A condition that indicates a state of resonance between the incident EM radiation and the NP surface excitations is mathematically derived. Our results shed light on the mechanism responsible for the strong absorption of light by such charged NPs. The outcome of this research could help to design a new generation of communication devices as well as a new technique for biological cell imaging.

  1. Tunable emission and excited state absorption induced optical limiting in Tb2(MoO4)3: Sm3+/Eu3+ nanophosphors

    NASA Astrophysics Data System (ADS)

    Mani, Kamal P.; Sreekanth, Perumbilavil; Vimal, G.; Biju, P. R.; Unnikrishnan, N. V.; Ittyachen, M. A.; Philip, Reji; Joseph, Cyriac

    2016-12-01

    Photoluminescence properties and optical limiting behavior of pure and Sm3+/Eu3+ doped Tb2(MoO4)3 nanophosphors are investigated. The prepared nanophosphors exhibit excellent emission when excited by UV light. Color-tunable emissions in Tb2-xSmx(MoO4)3 and Tb2-xEux(MoO4)3 are realized by employing different excitation wavelengths or by controlling the doping concentration of Sm3+ and Eu3+. Luminescence quantum yield and CIE chromatic coordinates of the prepared phosphors were also presented. Optical limiting properties of the samples are investigated by open aperture Z-scan technique using 5 ns laser pulses at 532 nm. Numerical fitting of the measured Z-scan data to the relevant nonlinear transmission equations reveals that the nonlinear absorption is arising from strong excited state absorption, along with weak absorption saturation and it is found that the optical nonlinearity of Tb2(MoO4)3 increases with Sm3+/Eu3+doping. Parameters such as saturation fluence, excited state absorption cross section and ground state absorption cross section of the samples have been determined numerically, from which the figure of merit for nonlinear absorption is calculated. The excited state absorption cross-section of the samples is found to be one order of magnitude higher than that of the ground state absorption cross-section, indicating strong reverse saturable absorption. These results indicate that Sm3+/Eu3+ doped Tb2(MoO4)3 nanophosphors are efficient media for UV/n-UV pumped LEDs, and are also potential candidates for designing efficient optical limiting devices for the protection of human eyes and sensitive optical detectors from harmful laser radiation.

  2. Risky alcohol use among reproductive-age men, not women, in Mae La refugee camp, Thailand, 2009

    PubMed Central

    2012-01-01

    Background Globally, alcohol use contributes to close to 4% of all deaths and is a leading cause of ill health and premature death among men of reproductive age. Problem alcohol use is an unaddressed public health issue among populations displaced by conflict. Assessing the magnitude of the problem and identifying affected groups and risk behaviours is difficult in mobile and unstable populations. Methods From 15–28 December 2009 we conducted a simple rapid screening test of risky alcohol use using the single item modified Short Assessment Screening Questionnaire (mSASQ) by all women currently enrolled in the antenatal care clinic in Mae La refugee camp, a long standing displaced setting on the Thai Burma border. Women self- reported and gave a secondary report of their male partners. Gender differences in alcohol use were further explored in semi-structured interviews with camp residents on attitudes, behaviours, and beliefs regarding alcohol and analysed thematically. Results Of 636 women screened in the antenatal clinic, almost none (0.2%, 95CI 0.0-0.9%) reported risky alcohol use prior to pregnancy, whereas around a quarter (24.4%, 95CI 21.2-27.9%) reported risky alcohol use by their male partners. Interviews with 97 camp residents described strong social controls against women’s alcohol use and men’s drinking to intoxication, despite a dominant perception that the social context of life in displacement promoted alcohol use and that controls are loosening. Conclusions As a stigmatised behaviour, alcohol use is difficult to assess, particularly in the context of highly mobile adult male populations: the simple assessment methods here show that it is feasible to obtain adequate data for the purposes of intervention design. The data suggest that risky drinking is common and normalised among men, but that the population may have been partially protected from rapid rises in problem alcohol use observed in nation-wide data from Thailand. The changing social

  3. Theory of absorption integrated optical sensor of gaseous materials

    NASA Astrophysics Data System (ADS)

    Egorov, A. A.

    2010-10-01

    The eigen and noneigen (leaky) modes of a three-layer planar integrated optical waveguide are described. The dispersion relation of a three-layer planar waveguide and other dependences are derived, and the cutoff conditions are analyzed. The diagram of propagation constants of the guided and radiation modes of an irregular asymmetric three-layer waveguide and the dependence of the electric field amplitudes of radiation modes of substrate on vertical coordinate in a tantalum integrated optical waveguide are presented. The operating principles of an absorption integrated optical waveguide sensor are investigated. The dependences of sensitivity of an integrated optical waveguide sensor on the sensory cell length, the coupling efficiency of the laser radiation into the waveguide, the absorption cross-section of the studied material, and the level of additive statistical noise are investigated. Some of the prospective areas of application of integrated-optical waveguide sensors are outlined.

  4. Self-Healing Efficiency of Cementitious Materials Containing Microcapsules Filled with Healing Adhesive: Mechanical Restoration and Healing Process Monitored by Water Absorption

    PubMed Central

    Li, Wenting; Jiang, Zhengwu; Yang, Zhenghong; Zhao, Nan; Yuan, Weizhong

    2013-01-01

    Autonomous crack healing of cementitious composite, a construction material that is susceptible to cracking, is of great significance to improve the serviceability and to prolong the longevity of concrete structures. In this study, the St-DVB microcapsules enclosing epoxy resins as the adhesive agent were embedded in cement paste to achieve self-healing capability. The self-healing efficiency was firstly assessed by mechanical restoration of the damaging specimens after being matured. The flexural and compressive configurations were both used to stimulate the localized and distributed cracks respectively. The effects of some factors, including the content of microcapsules, the curing conditions and the degree of damage on the healing efficiency were investigated. Water absorption was innovatively proposed to monitor and characterize the evolution of crack networks during the healing process. The healing cracks were observed by SEM-EDS following. The results demonstrated that the capsule-containing cement paste can achieve the various mechanical restorations depending on the curing condition and the degree of damage. But the voids generated by the surfactants compromised the strength. Though no noticeable improved stiffness obtained, the increasing fracture energy was seen particularly for the specimen acquiring 60% pre-damage. The sorptivity and amount of water decreased with cracks healing by the adhesive, which contributed to cut off and block ingress of water. The micrographs by SEM-EDS also validated that the cracks were bridged by the hardened epoxy as the dominated elements of C and O accounted for 95% by mass in the nearby cracks. PMID:24312328

  5. Self-healing efficiency of cementitious materials containing microcapsules filled with healing adhesive: mechanical restoration and healing process monitored by water absorption.

    PubMed

    Li, Wenting; Jiang, Zhengwu; Yang, Zhenghong; Zhao, Nan; Yuan, Weizhong

    2013-01-01

    Autonomous crack healing of cementitious composite, a construction material that is susceptible to cracking, is of great significance to improve the serviceability and to prolong the longevity of concrete structures. In this study, the St-DVB microcapsules enclosing epoxy resins as the adhesive agent were embedded in cement paste to achieve self-healing capability. The self-healing efficiency was firstly assessed by mechanical restoration of the damaging specimens after being matured. The flexural and compressive configurations were both used to stimulate the localized and distributed cracks respectively. The effects of some factors, including the content of microcapsules, the curing conditions and the degree of damage on the healing efficiency were investigated. Water absorption was innovatively proposed to monitor and characterize the evolution of crack networks during the healing process. The healing cracks were observed by SEM-EDS following. The results demonstrated that the capsule-containing cement paste can achieve the various mechanical restorations depending on the curing condition and the degree of damage. But the voids generated by the surfactants compromised the strength. Though no noticeable improved stiffness obtained, the increasing fracture energy was seen particularly for the specimen acquiring 60% pre-damage. The sorptivity and amount of water decreased with cracks healing by the adhesive, which contributed to cut off and block ingress of water. The micrographs by SEM-EDS also validated that the cracks were bridged by the hardened epoxy as the dominated elements of C and O accounted for 95% by mass in the nearby cracks.

  6. Effect of tannic acid on iron absorption in straw-colored fruit bats (Eidolon helvum).

    PubMed

    Lavin, Shana R; Chen, Zhensheng; Abrams, Steven A

    2010-01-01

    Excessive absorption and subsequent storage of dietary iron has been found in a variety of captively held birds and mammals, including fruit bats. It is thought that feeding a diet that is low in iron can prevent the onset of this disease; however, manufacturing a diet with commonly available foodstuffs that contains a sufficiently low iron concentration is difficult. An alternative is to feed captive animals that may be susceptible to this disease potential iron chelators such as tannins that may bind to iron and block its absorption. Using stable isotope methods established in humans, we measured iron bioavailability in straw-colored fruit bats (Eidolon helvum) and tested whether tannic acid significantly reduced the extent of iron absorption. Regardless of dose, tannic acid significantly reduced iron absorption (by 40%) and in the absence of tannic acid, iron absorption was extensive in this species (up to 30%), more so than in humans. Species susceptible to iron storage disease may efficiently absorb iron in the gut regardless of iron status, and supplementing these species with tannic acid in captivity may provide an alternative or additional means of preventing the development of this disease. (c) 2009 Wiley-Liss, Inc.

  7. Ingestion, enzymatic digestion and absorption of particles derived from different vegetal sources by the cockle Cerastoderma edule

    NASA Astrophysics Data System (ADS)

    Arambalza, U.; Urrutia, M. B.; Navarro, E.; Ibarrola, I.

    2010-10-01

    Ingestion, enzymatic digestion and absorption of particulate detrital matter derived from six different vegetal sources by the common cockle Cerastoderma edule was analyzed in a series of seasonal experiments performed in March, May and October 2005. Two green macroalgae: Ulva lactuca and Enteromorpha sp; two vascular plants: Spartina maritima and Juncus maritimus, the red macroalgae Gracilaria gracilis; and the microalgae Isochrysis galbana were used in experiments. Detrital matter was elaborated by freeze-drying, grinding and sieving (< 63 μm) vegetal tissues. Mono-specific detrital diets of similar organic content (≈ 60-70%) were elaborated by mixing detritus with ashed silt. We measured i) the biochemical composition of different detritus, ii) physiological components of the absorptive balance (i.e. clearance, ingestion, rejection and absorption rate and absorption efficiency), iii) the capability of the digestive gland to hydrolyze carbohydrates from different detritus (digestibility), as well as iv) glandular cellulase and xylanase activities. Detritus type, season and the interaction detritus-season exerted significant effects upon all the physiological components of absorptive balance. Effects were light at the pre-absorptive level, however, huge variations associated to absorption efficiency promoted large significant differences in absorption rates (AR) of different kind of detritus: irrespective of season, highest values corresponded to cockles fed the green macroalgae ( Ulva and Enteromorpha) and lowest to those fed the vascular plant Juncus maritimus. Recorded significant differences in enzymatic digestibility among detritus were found to explain ≈ 40% of differences recorded in AR, and the following regression could be fitted: AR = 0.232 (± 0.032) * Digestibility + 0,072 (± 0.015); r 2 = 0.415; F = 51.036; p < 0.001. Digestibility of Ulva and Enteromorpha was found to be significantly correlated with cellulase activity in the digestive gland

  8. Systematic determination of absolute absorption cross-section of individual carbon nanotubes

    PubMed Central

    Liu, Kaihui; Hong, Xiaoping; Choi, Sangkook; Jin, Chenhao; Capaz, Rodrigo B.; Kim, Jihoon; Wang, Wenlong; Bai, Xuedong; Louie, Steven G.; Wang, Enge; Wang, Feng

    2014-01-01

    Optical absorption is the most fundamental optical property characterizing light–matter interactions in materials and can be most readily compared with theoretical predictions. However, determination of optical absorption cross-section of individual nanostructures is experimentally challenging due to the small extinction signal using conventional transmission measurements. Recently, dramatic increase of optical contrast from individual carbon nanotubes has been successfully achieved with a polarization-based homodyne microscope, where the scattered light wave from the nanostructure interferes with the optimized reference signal (the reflected/transmitted light). Here we demonstrate high-sensitivity absorption spectroscopy for individual single-walled carbon nanotubes by combining the polarization-based homodyne technique with broadband supercontinuum excitation in transmission configuration. To our knowledge, this is the first time that high-throughput and quantitative determination of nanotube absorption cross-section over broad spectral range at the single-tube level was performed for more than 50 individual chirality-defined single-walled nanotubes. Our data reveal chirality-dependent behaviors of exciton resonances in carbon nanotubes, where the exciton oscillator strength exhibits a universal scaling law with the nanotube diameter and the transition order. The exciton linewidth (characterizing the exciton lifetime) varies strongly in different nanotubes, and on average it increases linearly with the transition energy. In addition, we establish an empirical formula by extrapolating our data to predict the absorption cross-section spectrum for any given nanotube. The quantitative information of absorption cross-section in a broad spectral range and all nanotube species not only provides new insight into the unique photophysics in one-dimensional carbon nanotubes, but also enables absolute determination of optical quantum efficiencies in important

  9. Systematic determination of absolute absorption cross-section of individual carbon nanotubes.

    PubMed

    Liu, Kaihui; Hong, Xiaoping; Choi, Sangkook; Jin, Chenhao; Capaz, Rodrigo B; Kim, Jihoon; Wang, Wenlong; Bai, Xuedong; Louie, Steven G; Wang, Enge; Wang, Feng

    2014-05-27

    Optical absorption is the most fundamental optical property characterizing light-matter interactions in materials and can be most readily compared with theoretical predictions. However, determination of optical absorption cross-section of individual nanostructures is experimentally challenging due to the small extinction signal using conventional transmission measurements. Recently, dramatic increase of optical contrast from individual carbon nanotubes has been successfully achieved with a polarization-based homodyne microscope, where the scattered light wave from the nanostructure interferes with the optimized reference signal (the reflected/transmitted light). Here we demonstrate high-sensitivity absorption spectroscopy for individual single-walled carbon nanotubes by combining the polarization-based homodyne technique with broadband supercontinuum excitation in transmission configuration. To our knowledge, this is the first time that high-throughput and quantitative determination of nanotube absorption cross-section over broad spectral range at the single-tube level was performed for more than 50 individual chirality-defined single-walled nanotubes. Our data reveal chirality-dependent behaviors of exciton resonances in carbon nanotubes, where the exciton oscillator strength exhibits a universal scaling law with the nanotube diameter and the transition order. The exciton linewidth (characterizing the exciton lifetime) varies strongly in different nanotubes, and on average it increases linearly with the transition energy. In addition, we establish an empirical formula by extrapolating our data to predict the absorption cross-section spectrum for any given nanotube. The quantitative information of absorption cross-section in a broad spectral range and all nanotube species not only provides new insight into the unique photophysics in one-dimensional carbon nanotubes, but also enables absolute determination of optical quantum efficiencies in important

  10. Enhanced Broadband Electromagnetic Absorption in Silicon Film with Photonic Crystal Surface and Random Gold Grooves Reflector

    PubMed Central

    Chen, Zhi-Hui; Qiao, Na; Yang, Yibiao; Ye, Han; Liu, Shaoding; Wang, Wenjie; Wang, Yuncai

    2015-01-01

    We show a hybrid structure consisting of Si film with photonic crystal surface and random triangular gold grooves reflector at the bottom, which is capable of realizing efficient, broad-band, wide-angle optical absorption. It is numerically demonstrated that the enhanced absorption in a broad wavelength range (0.3–9.9 μm) due to the scattering effect of both sides of the structure and the created resonance modes. Larger thickness and period are favored to enhance the absorption in broader wavelength range. Substantial electric field concentrates in the grooves of surface photonic crystal and in the Si film. Our structure is versatile for solar cells, broadband photodetection and stealth coating. PMID:26238270

  11. Enhancing crystalline silicon solar cell efficiency with SixGe1-x layers

    NASA Astrophysics Data System (ADS)

    Ali, Adnan; Cheow, S. L.; Azhari, A. W.; Sopian, K.; Zaidi, Saleem H.

    Crystalline silicon (c-Si) solar cell represents a cost effective, environment-friendly, and proven renewable energy resource. Industrially manufacturing of c-Si solar has now matured in terms of efficiency and cost. Continuing cost-effective efficiency enhancement requires transition towards thinner wafers in near term and thin-films in the long term. Successful implementation of either of these alternatives must address intrinsic optical absorption limitation of Si. Bandgap engineering through integration with SixGe1-x layers offers an attractive, inexpensive option. With the help of PC1D software, role of SixGe1-x layers in conventional c-Si solar cells has been intensively investigated in both wafer and thin film configurations by varying Ge concentration, thickness, and placement. In wafer configuration, increase in Ge concentration leads to enhanced absorption through bandgap broadening with an efficiency enhancement of 8% for Ge concentrations of less than 20%. At higher Ge concentrations, despite enhanced optical absorption, efficiency is reduced due to substantial lowering of open-circuit voltage. In 5-25-μm thickness, thin-film solar cell configurations, efficiency gain in excess of 30% is achievable. Therefore, SixGe1-x based thin-film solar cells with an order of magnitude reduction in costly Si material are ideally-suited both in terms of high efficiency and cost. Recent research has demonstrated significant improvement in epitaxially grown SixGe1-x layers on nanostructured Si substrates, thereby enhancing potential of this approach for next generation of c-Si based photovoltaics.

  12. Integration of a molten carbonate fuel cell with a direct exhaust absorption chiller

    NASA Astrophysics Data System (ADS)

    Margalef, Pere; Samuelsen, Scott

    A high market value exists for an integrated high-temperature fuel cell-absorption chiller product throughout the world. While high-temperature, molten carbonate fuel cells are being commercially deployed with combined heat and power (CHP) and absorption chillers are being commercially deployed with heat engines, the energy efficiency and environmental attributes of an integrated high-temperature fuel cell-absorption chiller product are singularly attractive for the emerging distributed generation (DG) combined cooling, heating, and power (CCHP) market. This study addresses the potential of cooling production by recovering and porting the thermal energy from the exhaust gas of a high-temperature fuel cell (HTFC) to a thermally activated absorption chiller. To assess the practical opportunity of serving an early DG-CCHP market, a commercially available direct fired double-effect absorption chiller is selected that closely matches the exhaust flow and temperature of a commercially available HTFC. Both components are individually modeled, and the models are then coupled to evaluate the potential of a DG-CCHP system. Simulation results show that a commercial molten carbonate fuel cell generating 300 kW of electricity can be effectively coupled with a commercial 40 refrigeration ton (RT) absorption chiller. While the match between the two "off the shelf" units is close and the simulation results are encouraging, the match is not ideal. In particular, the fuel cell exhaust gas temperature is higher than the inlet temperature specified for the chiller and the exhaust flow rate is not sufficient to achieve the potential heat recovery within the chiller heat exchanger. To address these challenges, the study evaluates two strategies: (1) blending the fuel cell exhaust gas with ambient air, and (2) mixing the fuel cell exhaust gases with a fraction of the chiller exhaust gas. Both cases are shown to be viable and result in a temperature drop and flow rate increase of the

  13. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  14. Petawatt laser absorption bounded

    PubMed Central

    Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

    2014-01-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials. PMID:24938656

  15. Highly efficient special sound absorbing solutions

    NASA Technical Reports Server (NTRS)

    Ionescu, M.; Petre-Lazar, S.

    1974-01-01

    Highly efficient special sound absorbing structures with the following criteria are considered: (1) A distribution surface of the sound absorbing material greater than that of the building element on which the structure is placed; (2) The highest possible absorption coefficient in the widest possible frequency band; and (3) adaptability to different construction and aesthetic conditions.

  16. [The study of CO2 cavity enhanced absorption and highly sensitive absorption spectroscopy].

    PubMed

    Pei, Shi-Xin; Gao, Xiao-Ming; Cui, Fen-Ping; Huang, Wei; Shao, Jie; Fan, Hong; Zhang, Wei-Jun

    2005-12-01

    Cavity enhanced absorption spectroscopy (CEAS) is a new spectral technology that is based on the cavity ring down absorption spectroscopy. In the present paper, a DFB encapsulation narrow line width tunable diode laser (TDL) was used as the light source. At the center output, the TDL radiation wavelength was 1.573 microm, and an optical cavity, which consisted of two high reflectivity mirrors (near 1.573 microm, the mirror reflectivity was about 0.994%), was used as a sample cell. A wavemeter was used to record the accurate frequency of the laser radiation. In the experiment, the method of scanning the optical cavity to change the cavity mode was used, when the laser frequency was coincident with one of the cavity mode; the laser radiation was coupled into the optical cavity and the detector could receive the light signals that escaped the optical cavity. As a result, the absorption spectrum of carbon dioxide weak absorption at low pressure was obtained with an absorption intensity of 1.816 x 10(-23) cm(-1) x (molecule x cm(-2)(-1) in a sample cell with a length of only 33.5 cm. An absorption sensitivity of about 3.62 x 10(-7) cm(-1) has been achieved. The experiment result indicated that the cavity enhanced absorption spectroscopy has the advantage of high sensivity, simple experimental setup, and easy operation.

  17. Exploration of parameters influencing the self-absorption losses in luminescent solar concentrators with an experimentally validated combined ray-tracing/Monte-Carlo model

    NASA Astrophysics Data System (ADS)

    Krumer, Zachar; van Sark, Wilfried G. J. H. M.; de Mello Donegá, Celso; Schropp, Ruud E. I.

    2013-09-01

    Luminescent solar concentrators (LSCs) are low cost photovoltaic devices, which reduce the amount of necessary semiconductor material per unit area of a photovoltaic solar energy converter by means of concentration. The device is comprised of a thin plastic plate in which luminescent species (fluorophores) have been incorporated.The fluorophores absorb the solar light and radiatively re-emit a part of the energy. Total internal reflection traps most of the emitted light inside the plate and wave-guides it to a narrow side facet with a solar cell attached, where conversion into electricity occurs. The eciency of such devices is as yet rather low, due to several loss mechanisms, of which self-absorption is of high importance. Combined ray-tracing and Monte-Carlosimulations is a widely used tool for efficiency estimations of LSC-devices prior to manufacturing. We have applied this method to a model experiment, in which we analysed the impact of self-absorption onto LSC-efficiency of fluorophores with different absorption/emission-spectral overlap (Stokes-shift): several organic dyes and semiconductor quantum dots (single compound and core/shell of type-II). These results are compared with the ones obtained experimentally demonstrating a good agreement. The validated model is used to investigate systematically the influence of spectral separation and luminescence quantum efficiency on the intensity loss inconsequence of increased self-absorption. The results are used to adopt a quantity called the self-absorption cross-section and establish it as reliable criterion for self-absorption properties of materials that can be obtained from fundamental data and has a more universal scope of application, than the currently used Stokes-shift.

  18. Au Nanomatryoshkas as Efficient Near-Infrared Photothermal Transducers for Cancer Treatment: Benchmarking against Nanoshells

    PubMed Central

    2015-01-01

    Au nanoparticles with plasmon resonances in the near-infrared (NIR) region of the spectrum efficiently convert light into heat, a property useful for the photothermal ablation of cancerous tumors subsequent to nanoparticle uptake at the tumor site. A critical aspect of this process is nanoparticle size, which influences both tumor uptake and photothermal efficiency. Here, we report a direct comparative study of ∼90 nm diameter Au nanomatryoshkas (Au/SiO2/Au) and ∼150 nm diameter Au nanoshells for photothermal therapeutic efficacy in highly aggressive triple negative breast cancer (TNBC) tumors in mice. Au nanomatryoshkas are strong light absorbers with 77% absorption efficiency, while the nanoshells are weaker absorbers with only 15% absorption efficiency. After an intravenous injection of Au nanomatryoshkas followed by a single NIR laser dose of 2 W/cm2 for 5 min, 83% of the TNBC tumor-bearing mice appeared healthy and tumor free >60 days later, while only 33% of mice treated with nanoshells survived the same period. The smaller size and larger absorption cross section of Au nanomatryoshkas combine to make this nanoparticle more effective than Au nanoshells for photothermal cancer therapy. PMID:24889266

  19. Tunable Spectrum Selectivity for Multiphoton Absorption with Enhanced Visible Light Trapping in ZnO Nanorods.

    PubMed

    Tan, Kok Hong; Lim, Fang Sheng; Toh, Alfred Zhen Yang; Zheng, Xia-Xi; Dee, Chang Fu; Majlis, Burhanuddin Yeop; Chai, Siang-Piao; Chang, Wei Sea

    2018-04-17

    Observation of visible light trapping in zinc oxide (ZnO) nanorods (NRs) correlated to the optical and photoelectrochemical properties is reported. In this study, ZnO NR diameter and c-axis length respond primarily at two different regions, UV and visible light, respectively. ZnO NR diameter exhibits UV absorption where large ZnO NR diameter area increases light absorption ability leading to high efficient electron-hole pair separation. On the other hand, ZnO NR c-axis length has a dominant effect in visible light resulting from a multiphoton absorption mechanism due to light reflection and trapping behavior in the free space between adjacent ZnO NRs. Furthermore, oxygen vacancies and defects in ZnO NRs are associated with the broad visible emission band of different energy levels also highlighting the possibility of the multiphoton absorption mechanism. It is demonstrated that the minimum average of ZnO NR c-axis length must satisfy the linear regression model of Z p,min = 6.31d to initiate the multiphoton absorption mechanism under visible light. This work indicates the broadening of absorption spectrum from UV to visible light region by incorporating a controllable diameter and c-axis length on vertically aligned ZnO NRs, which is important in optimizing the design and functionality of electronic devices based on light absorption mechanism. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Enhancement and inhibition of second-harmonic generation and absorption in a negative index cavity.

    PubMed

    de Ceglia, Domenico; D'Orazio, Antonella; De Sario, Marco; Petruzzelli, Vincenzo; Prudenzano, Francesco; Centini, Marco; Cappeddu, Mirko G; Bloemer, Mark J; Scalora, Michael

    2007-02-01

    We study second-harmonic generation in a negative-index material cavity. The transmission spectrum shows a bandgap between the electric and magnetic plasma frequencies. The nonlinear process is made efficient by local phase-matching conditions between a forward-propagating pump and a backward-propagating second-harmonic signal. By simultaneously exciting the cavity with counterpropagating pulses, and by varying their relative phase difference, one is able to enhance or inhibit linear absorption and the second-harmonic conversion efficiency.

  1. From Semi- to Full-Two-Dimensional Conjugated Side-Chain Design: A Way toward Comprehensive Solar Energy Absorption

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

    Chao, Pengjie; Wang, Huan; Qu, Shiwei

    Two polymers with fully two-dimensional (2D) conjugated side chains, 2D-PTB-Th and 2D-PTB-TTh, were synthesized and characterized through simultaneously integrating the 2D-TT and the 2D-BDT monomers onto the polymer backbone. Resulting from the synergistic effect from the conjugated side chains on both monomers, the two polymers showed remarkably efficient absorption of the sunlight and improved pi-pi intermolecular interactions for efficient charge carrier transport. The optimized bulk heterojunction device based on 2D-PTB-Th and PC71BM shows a higher PCE of 9.13% compared to PTB7-Th with a PCE of 8.26%, which corresponds to an approximately 10% improvement in solar energy conversion. The fully 2D-conjugatedmore » side-chain concept reported here developed a new molecular design strategy for polymer materials with enhanced sunlight absorption and efficient solar energy conversion.« less

  2. Microscopic nonlinear relativistic quantum theory of absorption of powerful x-ray radiation in plasma.

    PubMed

    Avetissian, H K; Ghazaryan, A G; Matevosyan, H H; Mkrtchian, G F

    2015-10-01

    The microscopic quantum theory of plasma nonlinear interaction with the coherent shortwave electromagnetic radiation of arbitrary intensity is developed. The Liouville-von Neumann equation for the density matrix is solved analytically considering a wave field exactly and a scattering potential of plasma ions as a perturbation. With the help of this solution we calculate the nonlinear inverse-bremsstrahlung absorption rate for a grand canonical ensemble of electrons. The latter is studied in Maxwellian, as well as in degenerate quantum plasma for x-ray lasers at superhigh intensities and it is shown that one can achieve the efficient absorption coefficient in these cases.

  3. 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.

  4. Triple-effect absorption refrigeration system with double-condenser coupling

    DOEpatents

    DeVault, R.C.; Biermann, W.J.

    1993-04-27

    A triple effect absorption refrigeration system is provided with a double-condenser coupling and a parallel or series circuit for feeding the refrigerant-containing absorbent solution through the high, medium, and low temperature generators utilized in the triple-effect system. The high temperature condenser receiving vaporous refrigerant from the high temperature generator is double coupled to both the medium temperature generator and the low temperature generator to enhance the internal recovery of heat within the system and thereby increase the thermal efficiency thereof.

  5. Triple-effect absorption refrigeration system with double-condenser coupling

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1993-01-01

    A triple effect absorption refrigeration system is provided with a double-condenser coupling and a parallel or series circuit for feeding the refrigerant-containing absorbent solution through the high, medium, and low temperature generators utilized in the triple-effect system. The high temperature condenser receiving vaporous refrigerant from the high temperature generator is double coupled to both the medium temperature generator and the low temperature generator to enhance the internal recovery of heat within the system and thereby increase the thermal efficiency thereof.

  6. Multiple acquisitions via sequential transfer of orphan spin polarization (MAeSTOSO): How far can we push residual spin polarization in solid-state NMR?

    NASA Astrophysics Data System (ADS)

    Gopinath, T.; Veglia, Gianluigi

    2016-06-01

    Conventional multidimensional magic angle spinning (MAS) solid-state NMR (ssNMR) experiments detect the signal arising from the decay of a single coherence transfer pathway (FID), resulting in one spectrum per acquisition time. Recently, we introduced two new strategies, namely DUMAS (DUal acquisition Magic Angle Spinning) and MEIOSIS (Multiple ExperIments via Orphan SpIn operatorS), that enable the simultaneous acquisitions of multidimensional ssNMR experiments using multiple coherence transfer pathways. Here, we combined the main elements of DUMAS and MEIOSIS to harness both orphan spin operators and residual polarization and increase the number of simultaneous acquisitions. We show that it is possible to acquire up to eight two-dimensional experiments using four acquisition periods per each scan. This new suite of pulse sequences, called MAeSTOSO for Multiple Acquisitions via Sequential Transfer of Orphan Spin pOlarization, relies on residual polarization of both 13C and 15N pathways and combines low- and high-sensitivity experiments into a single pulse sequence using one receiver and commercial ssNMR probes. The acquisition of multiple experiments does not affect the sensitivity of the main experiment; rather it recovers the lost coherences that are discarded, resulting in a significant gain in experimental time. Both merits and limitations of this approach are discussed.

  7. High efficiency laser-pumped emerald lasers

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

    Lai, S.T.

    1987-09-25

    Highly efficient laser operation has been achieved in emerald. In a quasi-cw laser-pumped emerald laser, 64% output slope efficiency has been measured at 768 nm, corresponding to a laser quantum yield of 76%. An output power of 1.6 W was reached at 3.6 W of pump power at 647.1 nm from a krypton laser, and was pump power limited. The emerald laser has a tuning range of 720 to 842 nm. The round trip loss excluding the excited state absorption (ESA) is 0.4%/cm. These results indicate the high laser efficiency and the high optical quality of the emerald attainable inmore » the present laser.« less

  8. Microwave-assisted extraction and a new determination method for total steroid saponins from Dioscorea zingiberensis C.H. Wright.

    PubMed

    Ren, Yao; Chen, Yu; Hu, Bohan; Wu, Hui; Lai, Furao; Li, Xiaofeng

    2015-12-01

    An efficient microwave-assisted extraction (MAE) technique was applied to isolate total steroid saponins from Dioscorea zingiberensis C.H. Wright (DZW). The optimal extracting conditions were established as 75% ethanol as solvent, ratio of solid/liquid 1:20 (g/ml), temperature 75 °C, irradiation power 600 W and three extraction cycles of 6 min each. Scanning electron microscopy (SEM) images of DZW processed by four different extractions provided visual evidence of the disruption effect on DZW. Diosgenin was quantified by HPLC and examined further by LC-ESI/MS after acid hydrolysis. Total steroid saponins were calculated using diosgenin from total steroid saponins. The MAE procedure was optimized, validated and compared with other conventional extraction processes. This report provides a convenient technology for the extraction and quantification of total saponins of DZW combining MAE with HPLC and LC-ESI/MS for the first time. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. The Fabrication and High-Efficiency Electromagnetic Wave Absorption Performance of CoFe/C Core-Shell Structured Nanocomposites

    NASA Astrophysics Data System (ADS)

    Wan, Gengping; Luo, Yongming; Wu, Lihong; Wang, Guizhen

    2018-03-01

    CoFe/C core-shell structured nanocomposites (CoFe@C) have been fabricated through the thermal decomposition of acetylene with CoFe2O4 as precursor. The as-prepared CoFe@C was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The results demonstrate that the carbon shell in CoFe@C has a poor crystallization with a thickness about 5-30 nm and a content approximately 48.5 wt.%. Due to a good combination between intrinsic magnetic properties and high-electrical conductivity, the CoFe@C exhibits not only excellent absorption intensity but also wide frequency bandwidth. The minimum RL value of CoFe@C can reach - 44 dB at a thickness of 4.0 mm, and RL values below - 10 dB is up to 4.3 GHz at a thickness of 2.5 mm. The present CoFe@C may be a potential candidate for microwave absorption application.

  10. Preparation and radar absorptive properties of BaFe12O19 -coated glass fiber

    NASA Astrophysics Data System (ADS)

    Jia, F.; Xu, M.; Bao, H. Q.; Cui, K.; Zhang, F.

    2016-07-01

    Traditional passive jamming materials such as chaff and foil showed some limitations in use because they can only reflect the electromagnetic wave. Therefore, to develop a kind of absorptive passive jamming material to make up for deficiencies of traditional passive jamming materials and improve the jamming efficiency is of great significance. In this paper, the BaFe12O19-coated glass fiber, used as a kind of radar absorptive chaff, was prepared by sol-gel dip-coating method. The effects of heat treatment temperature, heat treatment time and coating times on film quality, tensile strength and attenuation efficiency of the samples were discussed. The study shows that an increase of the heat treatment temperature and an extension of the heat treatment time is conducive to the growth of barium ferrite grain, while they would introduce the loss of chaff strength at the same time. In addition, multi-coating process can improve the film quality and attenuation efficiency of the sample. Data show that the 10 times coated samples have a best reflectivity of (15GHz, -6.65dB) and the bandwidth of reflectivity lower than -5dB is11.8 GHz. According to the test results, the prepared material has certain attenuation efficiency in the range of 2GHz-18GHz, having a high practical value.

  11. The Rotational Spectrum of Complex Organic Molecules: 2(N)-METHYLAMINOETHANOL

    NASA Astrophysics Data System (ADS)

    Melandri, S.; Maris, A.; Calabrese, C.

    2013-06-01

    The detection of molecules in space, is based on their spectroscopic features and high resolution spectral data is needed to allow an unambiguous identification of them. Many of the molecules detected in space are complex organic molecules containing chains of carbon atoms and which therefore show a high degree of molecular flexibility. The high number of low energy conformations and the presence of large amplitude motions on shallow potential energy surfaces are peculiar to this kind of systems. The presence of a high number of stable conformers - often interconverting through small energy barriers - usually gives rise to very complex spectra, which represent a challenge for spectroscopic and computational methods. We report the rotational study of methylaminoethanol (MAE) performed by Free Jet Absorption Microwave Spectrocopy (FJAMW). For this species it has proved essential to compute the complete potential energy surfaces related to the low amplitude modes. This has been calculated at the B3LYP/6-311++G** level of theory while the stable geometries have been characterized MP2/6-311++G**. The interest in the conformational properties of MAE is twofold: in the first place, aminoethanol and thus also MAE can be considered precursors of aminoacids in the interstellar medium and secondly, the MAE side chain is present in important biological molecules such as adrenaline. The conformational preferences of MAE are dominated by the intramolecular hydrogen bond between the OH and NH2 groups and its flexibility and asymmetry generate a very high number of conformers. 24 stable conformations have been predicted and two conformers were observed by FJAMW spectroscopy with our 60-72 GHz spectrometer. With respect to a previous study we have extended the observed frequency range, partly reassigned the rotational spectrum of one of the conformers and determined the nuclear quadrupole constants. The search for higher energy conformers has also been undertaken. S. Charnley, in

  12. Hydrogen Sulfide and Ionic Liquids: Absorption, Separation, and Oxidation.

    PubMed

    Chiappe, Cinzia; Pomelli, Christian Silvio

    2017-06-01

    Economical and environmental concerns are the main motivations for development of energy-efficient processes and new eco-friendly materials for the capture of greenhouse gases. Currently, H 2 S capture is dominated by physical and/or chemical absorption technologies, which are, however, energy intensive and often problematic from an environmental point of view due to emission of volatile solvent components. Ionic liquids have been proposed as a promising alternative to conventional solvents because of their low volatility and other interesting properties. The aim of the present review paper is to provide a detailed overview of the achievements and difficulties that have been encountered in finding suitable ionic liquids for H 2 S capture. The effect of ionic liquid anions, cations, and functional groups on the H 2 S absorption, separation, and oxidation are highlighted. Recent developments on yet scarcely available molecular simulations and on the development of robust predictive methods are also discussed.

  13. Metal powder absorptivity: Modeling and experiment

    DOE PAGES

    Boley, C. D.; Mitchell, S. C.; Rubenchik, A. M.; ...

    2016-08-10

    Here, we present results of numerical modeling and direct calorimetric measurements of the powder absorptivity for a number of metals. The modeling results generally correlate well with experiment. We show that the powder absorptivity is determined, to a great extent, by the absorptivity of a flat surface at normal incidence. Our results allow the prediction of the powder absorptivity from normal flat-surface absorptivity measurements.

  14. Metal powder absorptivity: Modeling and experiment

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

    Boley, C. D.; Mitchell, S. C.; Rubenchik, A. M.

    Here, we present results of numerical modeling and direct calorimetric measurements of the powder absorptivity for a number of metals. The modeling results generally correlate well with experiment. We show that the powder absorptivity is determined, to a great extent, by the absorptivity of a flat surface at normal incidence. Our results allow the prediction of the powder absorptivity from normal flat-surface absorptivity measurements.

  15. Two-Photon-Absorption Scheme for Optical Beam Tracking

    NASA Technical Reports Server (NTRS)

    Ortiz, Gerardo G.; Farr, William H.

    2011-01-01

    A new optical beam tracking approach for free-space optical communication links using two-photon absorption (TPA) in a high-bandgap detector material was demonstrated. This tracking scheme is part of the canonical architecture described in the preceding article. TPA is used to track a long-wavelength transmit laser while direct absorption on the same sensor simultaneously tracks a shorter-wavelength beacon. The TPA responsivity was measured for silicon using a PIN photodiode at a laser beacon wavelength of 1,550 nm. As expected, the responsivity shows a linear dependence with incident power level. The responsivity slope is 4.5 x 10(exp -7) A/W2. Also, optical beam spots from the 1,550-nm laser beacon were characterized on commercial charge coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) imagers with as little as 13.7 microWatts of optical power (see figure). This new tracker technology offers an innovative solution to reduce system complexity, improve transmit/receive isolation, improve optical efficiency, improve signal-to-noise ratio (SNR), and reduce cost for free-space optical communications transceivers.

  16. Investigation on the energy absorption performance of a fixed-bottom pressure-differential wave energy converter

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

    Babarit, A.; Wendt, F.; Yu, Y. -H.

    2017-04-01

    In this article, we investigate the energy absorption performance of a fixed-bottom pressure-differential wave energy converter. Two versions of the technology are considered: one has the moving surfaces on the bottom of the air chambers whereas the other has the moving surfaces on the top. We developed numerical models in the frequency domain, thereby enabling the power absorption of the two versions of the device to be assessed. It is observed that the moving surfaces on the top allow for easier tuning of the natural period of the system. Taking into account stroke limitations, the design is optimized. Results indicatemore » that the pressure-differential wave energy converter is a highly efficient technology both with respect to energy absorption and selected economic performance indicators.« less

  17. Broadband light absorption enhancement in dye-sensitized solar cells with Au-Ag alloy popcorn nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Qi; Liu, Fang; Liu, Yuxiang; Cui, Kaiyu; Feng, Xue; Zhang, Wei; Huang, Yidong

    2013-07-01

    In this paper, we present an investigation on the use of Au-Ag alloy popcorn-shaped nanoparticles (NPs) to realise the broadband optical absorption enhancement of dye-sensitized solar cells (DSCs). Both simulation and experimental results indicate that compared with regular plasmonic NPs, such as nano-spheres, irregular popcorn-shaped alloy NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths. The power conversion efficiency (PCE) of DSCs is enhanced by 16% from 5.26% to 6.09% by incorporating 2.38 wt% Au-Ag alloy popcorn NPs. Moreover, by adding a scattering layer on the exterior of the counter electrode, the popcorn NPs demonstrate an even stronger ability to increase the PCE by 32% from 5.94% to 7.85%, which results from the more efficient excitation of the LSP mode on the popcorn NPs.

  18. Broadband light absorption enhancement in dye-sensitized solar cells with Au-Ag alloy popcorn nanoparticles.

    PubMed

    Xu, Qi; Liu, Fang; Liu, Yuxiang; Cui, Kaiyu; Feng, Xue; Zhang, Wei; Huang, Yidong

    2013-01-01

    In this paper, we present an investigation on the use of Au-Ag alloy popcorn-shaped nanoparticles (NPs) to realise the broadband optical absorption enhancement of dye-sensitized solar cells (DSCs). Both simulation and experimental results indicate that compared with regular plasmonic NPs, such as nano-spheres, irregular popcorn-shaped alloy NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths. The power conversion efficiency (PCE) of DSCs is enhanced by 16% from 5.26% to 6.09% by incorporating 2.38 wt% Au-Ag alloy popcorn NPs. Moreover, by adding a scattering layer on the exterior of the counter electrode, the popcorn NPs demonstrate an even stronger ability to increase the PCE by 32% from 5.94% to 7.85%, which results from the more efficient excitation of the LSP mode on the popcorn NPs.

  19. Broadband light absorption enhancement in dye-sensitized solar cells with Au-Ag alloy popcorn nanoparticles

    PubMed Central

    Xu, Qi; Liu, Fang; Liu, Yuxiang; Cui, Kaiyu; Feng, Xue; Zhang, Wei; Huang, Yidong

    2013-01-01

    In this paper, we present an investigation on the use of Au-Ag alloy popcorn-shaped nanoparticles (NPs) to realise the broadband optical absorption enhancement of dye-sensitized solar cells (DSCs). Both simulation and experimental results indicate that compared with regular plasmonic NPs, such as nano-spheres, irregular popcorn-shaped alloy NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths. The power conversion efficiency (PCE) of DSCs is enhanced by 16% from 5.26% to 6.09% by incorporating 2.38 wt% Au-Ag alloy popcorn NPs. Moreover, by adding a scattering layer on the exterior of the counter electrode, the popcorn NPs demonstrate an even stronger ability to increase the PCE by 32% from 5.94% to 7.85%, which results from the more efficient excitation of the LSP mode on the popcorn NPs. PMID:23817586

  20. Single frequency 1560nm Er:Yb fiber amplifier with 207W output power and 50.5% slope efficiency

    NASA Astrophysics Data System (ADS)

    Creeden, Daniel; Pretorius, Herman; Limongelli, Julia; Setzler, Scott D.

    2016-03-01

    High power fiber lasers/amplifiers in the 1550nm spectral region have not scaled as rapidly as Yb-, Tm-, or Ho-doped fibers. This is primarily due to the low gain of the erbium ion. To overcome the low pump absorption, Yb is typically added as a sensitizer. Although this helps the pump absorption, it also creates a problem with parasitic lasing of the Yb ions under strong pumping conditions, which generally limits output power. Other pump schemes have shown high efficiency through resonant pumping of erbium only without the need for Yb as a sensitizer [1-2]. Although this can enable higher power scaling due to a decrease in the thermal loading, resonant pumping methods require long fiber lengths due to pump bleaching, which may limit the power scaling which can be achieved for single frequency output. By using an Er:Yb fiber and pumping in the minima of the Yb pump absorption at 940nm, we have been able to simultaneously generate high power, single frequency output at 1560nm while suppressing the 1-micron ASE and enabling higher efficiency compared to pumping at the absorption peak at 976nm. We have demonstrated single frequency amplification (540Hz linewidth) to 207W average output power with 49.3% optical efficiency (50.5% slope efficiency) in an LMA Er:Yb fiber. We believe this is the highest reported efficiency from a high power 9XXnm pumped Er:Yb-doped fiber amplifier. This is significantly more efficient that the best-reported efficiency for high power Er:Yb doped fibers, which, to-date, has been limited to ~41% slope efficiency [3].

  1. Time-dependent oral absorption models

    NASA Technical Reports Server (NTRS)

    Higaki, K.; Yamashita, S.; Amidon, G. L.

    2001-01-01

    The plasma concentration-time profiles following oral administration of drugs are often irregular and cannot be interpreted easily with conventional models based on first- or zero-order absorption kinetics and lag time. Six new models were developed using a time-dependent absorption rate coefficient, ka(t), wherein the time dependency was varied to account for the dynamic processes such as changes in fluid absorption or secretion, in absorption surface area, and in motility with time, in the gastrointestinal tract. In the present study, the plasma concentration profiles of propranolol obtained in human subjects following oral dosing were analyzed using the newly derived models based on mass balance and compared with the conventional models. Nonlinear regression analysis indicated that the conventional compartment model including lag time (CLAG model) could not predict the rapid initial increase in plasma concentration after dosing and the predicted Cmax values were much lower than that observed. On the other hand, all models with the time-dependent absorption rate coefficient, ka(t), were superior to the CLAG model in predicting plasma concentration profiles. Based on Akaike's Information Criterion (AIC), the fluid absorption model without lag time (FA model) exhibited the best overall fit to the data. The two-phase model including lag time, TPLAG model was also found to be a good model judging from the values of sum of squares. This model also described the irregular profiles of plasma concentration with time and frequently predicted Cmax values satisfactorily. A comparison of the absorption rate profiles also suggested that the TPLAG model is better at prediction of irregular absorption kinetics than the FA model. In conclusion, the incorporation of a time-dependent absorption rate coefficient ka(t) allows the prediction of nonlinear absorption characteristics in a more reliable manner.

  2. Intestinal Water Absorption Varies with Expected Dietary Water Load among Bats but Does Not Drive Paracellular Nutrient Absorption.

    PubMed

    Price, Edwin R; Brun, Antonio; Gontero-Fourcade, Manuel; Fernández-Marinone, Guido; Cruz-Neto, Ariovaldo P; Karasov, William H; Caviedes-Vidal, Enrique

    2015-01-01

    Rapid absorption and elimination of dietary water should be particularly important to flying species and were predicted to vary with the water content of the natural diet. Additionally, high water absorption capacity was predicted to be associated with high paracellular nutrient absorption due to solvent drag. We compared the water absorption rates of sanguivorous, nectarivorous, frugivorous, and insectivorous bats in intestinal luminal perfusions. High water absorption rates were associated with high expected dietary water load but were not highly correlated with previously measured rates of (paracellular) arabinose clearance. In conjunction with these tests, we measured water absorption and the paracellular absorption of nutrients in the intestine and stomach of vampire bats using luminal perfusions to test the hypothesis that the unique elongated vampire stomach is a critical site of water absorption. Vampire bats' gastric water absorption was high compared to mice but not compared to their intestines. We therefore conclude that (1) dietary water content has influenced the evolution of intestinal water absorption capacity in bats, (2) solvent drag is not the only driver of paracellular nutrient absorption, and (3) the vampire stomach is a capable but not critical location for water absorption.

  3. The role of the surfaces in the photon absorption in Ge nanoclusters embedded in silica.

    PubMed

    Cosentino, Salvatore; Mirabella, Salvatore; Miritello, Maria; Nicotra, Giuseppe; Lo Savio, Roberto; Simone, Francesca; Spinella, Corrado; Terrasi, Antonio

    2011-02-11

    The usage of semiconductor nanostructures is highly promising for boosting the energy conversion efficiency in photovoltaics technology, but still some of the underlying mechanisms are not well understood at the nanoscale length. Ge quantum dots (QDs) should have a larger absorption and a more efficient quantum confinement effect than Si ones, thus they are good candidate for third-generation solar cells. In this work, Ge QDs embedded in silica matrix have been synthesized through magnetron sputtering deposition and annealing up to 800°C. The thermal evolution of the QD size (2 to 10 nm) has been followed by transmission electron microscopy and X-ray diffraction techniques, evidencing an Ostwald ripening mechanism with a concomitant amorphous-crystalline transition. The optical absorption of Ge nanoclusters has been measured by spectrophotometry analyses, evidencing an optical bandgap of 1.6 eV, unexpectedly independent of the QDs size or of the solid phase (amorphous or crystalline). A simple modeling, based on the Tauc law, shows that the photon absorption has a much larger extent in smaller Ge QDs, being related to the surface extent rather than to the volume. These data are presented and discussed also considering the outcomes for application of Ge nanostructures in photovoltaics.PACS: 81.07.Ta; 78.67.Hc; 68.65.-k.

  4. 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.

  5. Extreme absorption enhancement in ZnTe:O/ZnO intermediate band core-shell nanowires by interplay of dielectric resonance and plasmonic bowtie nanoantennas.

    PubMed

    Nie, Kui-Ying; Li, Jing; Chen, Xuanhu; Xu, Yang; Tu, Xuecou; Ren, Fang-Fang; Du, Qingguo; Fu, Lan; Kang, Lin; Tang, Kun; Gu, Shulin; Zhang, Rong; Wu, Peiheng; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati; Ye, Jiandong

    2017-08-08

    Intermediate band solar cells (IBSCs) are conceptual and promising for next generation high efficiency photovoltaic devices, whereas, IB impact on the cell performance is still marginal due to the weak absorption of IB states. Here a rational design of a hybrid structure composed of ZnTe:O/ZnO core-shell nanowires (NWs) with Al bowtie nanoantennas is demonstrated to exhibit strong ability in tuning and enhancing broadband light response. The optimized nanowire dimensions enable absorption enhancement by engineering leaky-mode dielectric resonances. It maximizes the overlap of the absorption spectrum and the optical transitions in ZnTe:O intermediate-band (IB) photovoltaic materials, as verified by the enhanced photoresponse especially for IB states in an individual nanowire device. Furthermore, by integrating Al bowtie antennas, the enhanced exciton-plasmon coupling enables the notable improvement in the absorption of ZnTe:O/ZnO core-shell single NW, which was demonstrated by the profound enhancement of photoluminescence and resonant Raman scattering. The marriage of dielectric and metallic resonance effects in subwavelength-scale nanowires opens up new avenues for overcoming the poor absorption of sub-gap photons by IB states in ZnTe:O to achieve high-efficiency IBSCs.

  6. Plasmonic Structure Integrated Single-Photon Detector Configurations to Improve Absorptance and Polarization Contrast

    PubMed Central

    Csete, Mária; Szekeres, Gábor; Szenes, András; Szalai, Anikó; Szabó, Gábor

    2015-01-01

    Configurations capable of maximizing both the absorption component of system detection efficiency and the achievable polarization contrast were determined for 1550 nm polarized light illumination of different plasmonic structure integrated superconducting nanowire single-photon detectors (SNSPDs) consisting of p = 264 nm and P = 792 nm periodic niobium nitride (NbN) patterns on silica substrate. Global effective NbN absorptance maxima appear in case of p/s-polarized light illumination in S/P-orientation (γ = 90°/0° azimuthal angle) and the highest polarization contrast is attained in S-orientation of all devices. Common nanophotonical origin of absorptance enhancement is collective resonance on nanocavity gratings with different profiles, which is promoted by coupling between localized modes in quarter-wavelength metal-insulator-metal nanocavities and laterally synchronized Brewster-Zenneck-type surface waves in integrated SNSPDs possessing a three-quarter-wavelength-scaled periodicity. The spectral sensitivity and dispersion characteristics reveal that device design specific optimal configurations exist. PMID:25654724

  7. Highly Efficient Perovskite Solar Cells with Substantial Reduction of Lead Content.

    PubMed

    Liu, Chong; Fan, Jiandong; Li, Hongliang; Zhang, Cuiling; Mai, Yaohua

    2016-10-18

    Despite organometal halide perovskite solar cells have recently exhibited a significant leap in efficiency, the Sn-based perovskite solar cells still suffer from low efficiency. Here, a series homogeneous CH 3 NH 3 Pb (1-x) Sn x I 3 (0 ≤ x ≤ 1) perovskite thin films with full coverage were obtained via solvent engineering. In particular, the intermediate complexes of PbI 2 /(SnI 2 )∙(DMSO) x were proved to retard the crystallization of CH 3 NH 3 SnI 3 , thus allowing the realization of high quality Sn-introduced perovskite thin films. The external quantum efficiency (EQE) of as-prepared solar cells were demonstrated to extend a broad absorption minimum over 50% in the wavelength range from 350 to 950 nm accompanied by a noteworthy absorption onset up to 1050 nm. The CH 3 NH 3 Pb 0.75 Sn 0.25 I 3 perovskite solar cells with inverted structure were consequently realized with maximum power conversion efficiency (PCE) of 14.12%.

  8. Spatial decoupling of light absorption and catalytic activity of Ni-Mo-loaded high-aspect-ratio silicon microwire photocathodes

    NASA Astrophysics Data System (ADS)

    Vijselaar, Wouter; Westerik, Pieter; Veerbeek, Janneke; Tiggelaar, Roald M.; Berenschot, Erwin; Tas, Niels R.; Gardeniers, Han; Huskens, Jurriaan

    2018-03-01

    A solar-driven photoelectrochemical cell provides a promising approach to enable the large-scale conversion and storage of solar energy, but requires the use of Earth-abundant materials. Earth-abundant catalysts for the hydrogen evolution reaction, for example nickel-molybdenum (Ni-Mo), are generally opaque and require high mass loading to obtain high catalytic activity, which in turn leads to parasitic light absorption for the underlying photoabsorber (for example silicon), thus limiting production of hydrogen. Here, we show the fabrication of a highly efficient photocathode by spatially and functionally decoupling light absorption and catalytic activity. Varying the fraction of catalyst coverage over the microwires, and the pitch between the microwires, makes it possible to deconvolute the contributions of catalytic activity and light absorption to the overall device performance. This approach provided a silicon microwire photocathode that exhibited a near-ideal short-circuit photocurrent density of 35.5 mA cm-2, a photovoltage of 495 mV and a fill factor of 62% under AM 1.5G illumination, resulting in an ideal regenerative cell efficiency of 10.8%.

  9. Electron photodetachment from gas phase peptide dianions. Relation with optical absorption properties.

    PubMed

    Joly, Laure; Antoine, Rodolphe; Broyer, Michel; Lemoine, Jérôme; Dugourd, Philippe

    2008-02-07

    Electron detachment from peptide dianions is studied as a function of the laser wavelength. The first step for the detachment is a resonant electronic excitation of the dianions. Electronic excitation spectra are reported for three peptides, including gramicidin. A comparative study of the detachment yield for 13 peptides was performed at 260 nm and at 220 nm. At 260 nm, the detachment yield is mainly driven by the sum of the absorption coefficients of the aromatic amino acids that are contained in the peptide. At 220 nm, no direct relation is observed between the electron photodetachement yields and the sum of absorption efficiencies. At this wavelength, the sequence and the structure of the peptide may have an influence on the photodetachment process.

  10. An organoboron compound with a wide absorption spectrum for solar cell applications.

    PubMed

    Liu, Fangbin; Ding, Zicheng; Liu, Jun; Wang, Lixiang

    2017-11-09

    Organoboron compounds offer new approaches to tune the electronic structures of π-conjugated molecules. In this work, an electron acceptor (M-BNBP4P-1) is developed by endcapping an organoboron core unit with two strong electron-withdrawing groups. M-BNBP4P-1 exhibits a unique wide absorption spectrum with two strong absorption bands in the long wavelength region (λ max = 771 nm) and the short wavelength region (λ max = 502 nm), which indicate superior sunlight harvesting capability. This is due to its special electronic structure, i.e. a delocalized LUMO and a localized HOMO. Prototype solution-processed organic solar cells based on M-BNBP4P-1 show a power conversion efficiency of 7.06% and a wide photoresponse from 350 nm to 880 nm.

  11. Enhanced light absorption in an ultrathin silicon solar cell utilizing plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Xiao, Sanshui; Mortensen, Niels A.

    2012-10-01

    Nowadays, bringing photovoltaics to the market is mainly limited by high cost of electricity produced by the photovoltaic solar cell. Thin-film photovoltaics offers the potential for a significant cost reduction compared to traditional photovoltaics. However, the performance of thin-film solar cells is generally limited by poor light absorption. We propose an ultrathin-film silicon solar cell configuration based on SOI structure, where the light absorption is enhanced by use of plasmonic nanostructures. By placing a one-dimensional plasmonic nanograting on the bottom of the solar cell, the generated photocurrent for a 200 nm-thickness crystalline silicon solar cell can be enhanced by 90% in the considered wavelength range. These results are paving a promising way for the realization of high-efficiency thin-film solar cells.

  12. Aerosolized liposomes with dipalmitoyl phosphatidylcholine enhance pulmonary absorption of encapsulated insulin compared with co-administered insulin.

    PubMed

    Chono, Sumio; Togami, Kohei; Itagaki, Shirou

    2017-11-01

    We have previously shown that aerosolized liposomes with dipalmitoyl phosphatidylcholine (DPPC) enhance the pulmonary absorption of encapsulated insulin. In this study, we aimed to compare insulin encapsulated into the liposomes versus co-administration of empty liposomes and unencapsulated free insulin, where the DPCC liposomes would serve as absorption enhancer. The present study provides the useful information for development of noninvasive treatment of diabetes. Co-administration of empty DPPC liposomes and unencapsulated free insulin was investigated in vivo to assess the potential enhancement in protein pulmonary absorption. Co-administration was compared to DPPC liposomes encapsulating insulin, and free insulin. DPPC liposomes enhanced the pulmonary absorption of unencapsulated free insulin; however, the enhancing effect was lower than that of the DPPC liposomes encapsulating insulin. The mechanism of the pulmonary absorption of unencapsulated free insulin by DPPC liposomes involved the opening of epithelial cell space in alveolar mucosa, and not mucosal cell damage, similar to that of the DPPC liposomes encapsulating insulin. In an in vitro stability test, insulin in the alveolar mucus layer that covers epithelial cells was stable. These findings suggest that, although unencapsulated free insulin spreads throughout the alveolar mucus layer, the concentration of insulin released near the absorption surface is increased by the encapsulation of insulin into DPPC liposomes and the absorption efficiency is also increased. We revealed that the encapsulation of insulin into DPPC liposomes is more effective for pulmonary insulin absorption than co-administration of DPPC liposomes and unencapsulated free insulin.

  13. Efficient color display using low-absorption in-pixel color filters

    NASA Technical Reports Server (NTRS)

    Wang, Yu (Inventor)

    2000-01-01

    A display system having a non-absorbing and reflective color filtering array and a reflector to improve light utilization efficiency. One implementation of the color filtering array uses a surface plasmon filter having two symmetric metal-dielectric interfaces coupled with each other to produce a transmission optical wave at a surface plasmon resonance wavelength at one interface from a p-polarized input beam on the other interface. Another implementation of the color filtering array uses a metal-film interference filter having two dielectric layers and three metallic films.

  14. Electromagnetic Spectrum Analysis and Its Influence on the Photoelectric Conversion Efficiency of Solar Cells.

    PubMed

    Hu, Kexiang; Ding, Enjie; Wangyang, Peihua; Wang, Qingkang

    2016-06-01

    The electromagnetic spectrum and the photoelectric conversion efficiency of the silicon hexagonal nanoconical hole (SiHNH) arrays based solar cells is systematically analyzed according to Rigorous Coupled Wave Analysis (RCWA) and Modal Transmission Line (MTL) theory. An ultimate efficiency of the optimized SiHNH arrays based solar cell is up to 31.92% in consideration of the absorption spectrum, 4.52% higher than that of silicon hexagonal nanoconical frustum (SiHNF) arrays. The absorption enhancement of the SiHNH arrays is due to its lower reflectance and more supported guided-mode resonances, and the enhanced ultimate efficiency is insensitive to bottom diameter (D(bot)) of nanoconical hole and the incident angle. The result provides an additional guideline for the nanostructure surface texturing fabrication design for photovoltaic applications.

  15. Relative importance of black carbon, brown carbon, and absorption enhancement from clear coatings in biomass burning emissions

    NASA Astrophysics Data System (ADS)

    Pokhrel, Rudra P.; Beamesderfer, Eric R.; Wagner, Nick L.; Langridge, Justin M.; Lack, Daniel A.; Jayarathne, Thilina; Stone, Elizabeth A.; Stockwell, Chelsea E.; Yokelson, Robert J.; Murphy, Shane M.

    2017-04-01

    A wide range of globally significant biomass fuels were burned during the fourth Fire Lab at Missoula Experiment (FLAME-4). A multi-channel photoacoustic absorption spectrometer (PAS) measured dry absorption at 405, 532, and 660 nm and thermally denuded (250 °C) absorption at 405 and 660 nm. Absorption coefficients were broken into contributions from black carbon (BC), brown carbon (BrC), and lensing following three different methodologies, with one extreme being a method that assumes the thermal denuder effectively removes organics and the other extreme being a method based on the assumption that black carbon (BC) has an Ångström exponent of unity. The methodologies employed provide ranges of potential importance of BrC to absorption but, on average, there was a difference of a factor of 2 in the ratio of the fraction of absorption attributable to BrC estimated by the two methods. BrC absorption at shorter visible wavelengths is of equal or greater importance to that of BC, with maximum contributions of up to 92 % of total aerosol absorption at 405 nm and up to 58 % of total absorption at 532 nm. Lensing is estimated to contribute a maximum of 30 % of total absorption, but typically contributes much less than this. Absorption enhancements and the estimated fraction of absorption from BrC show good correlation with the elemental-carbon-to-organic-carbon ratio (EC / OC) of emitted aerosols and weaker correlation with the modified combustion efficiency (MCE). Previous studies have shown that BrC grows darker (larger imaginary refractive index) as the ratio of black to organic aerosol (OA) mass increases. This study is consistent with those findings but also demonstrates that the fraction of total absorption attributable to BrC shows the opposite trend: increasing as the organic fraction of aerosol emissions increases and the EC / OC ratio decreases.

  16. Liver metabolomics analysis associated with feed efficiency on steers

    USDA-ARS?s Scientific Manuscript database

    The liver represents a metabolic crossroad regulating and modulating nutrients available from digestive tract absorption to the peripheral tissues. To identify potential differences in liver function that lead to differences in feed efficiency, liver metabolomic analysis was conducted using ultra-pe...

  17. Observation of Gate-Tunable Coherent Perfect Absorption of Terahertz Waves in Graphene

    NASA Astrophysics Data System (ADS)

    Kocabas, Coskun; Kakenov, Nurbek; Balci, Osman; Takan, Taylan; Ozkan, Vedat Ali; Altan, Hakan

    We report experimental observation of electrically tunable coherent perfect absorption (CPA) of terahertz (THz) radiation in graphene. We develop a reflection-type tunable THz cavity formed by a large-area graphene layer, a metallic reflective electrode, and an electrolytic medium in between. Ionic gating in the THz cavity allows us to tune the Fermi energy of graphene up to 1 eV and to achieve a critical coupling condition at 2.8 THz with absorption of 100 %. With the enhanced THz absorption, we were able to measure the Fermi energy dependence of the transport scattering time of highly doped graphene. Furthermore, we demonstrate flexible active THz surfaces that yield large modulation in the THz reflectivity with low insertion losses. We anticipate that the gate-tunable CPA will lead to efficient active THz optoelectronics applications. This work was partially supported by the Scientific and Technological Research Council of Turkey (TUBITAK) Grant No. 114F379 and the European Research Council (ERC) Consolidator Grant ERC-682723 SmartGraphene. N.K. acknowledges the TUBITAK-BIDEB 2215.

  18. Absorption of a linear (L2) and a cyclic (D4) siloxane using different oils: application to biogas treatment.

    PubMed

    Rojas Devia, Carolina; Subrenat, Albert

    2013-01-01

    Hydrophobic volatile methyl siloxanes (VMS), such as hexamethyldisiloxane (L2) and octamethylcyclotetrasiloxane (D4), present a low solubility in water. An alternative treatment by absorption into hydrophobic absorbents was therefore studied. For this purpose, three different absorbents, motor oil, cutting oil and a water-cutting oil mixture, were selected with the aim of re-using a waste product. The set of experiments was carried out in a bubble column, where parameters such as inlet concentration, residence time and temperature were studied. The best performance for the removal of both siloxanes, in terms of absorption capacity, was observed for motor oil, particularly for D4. In fact, motor oil removal efficiency for D 4 was 80%, whereas for L2 it was 60%, indicating that D 4 is more easily absorbed than L2. In the case of water-cutting oil, this showed a mass transfer enhancement from the gas phase to the liquid phase compared with water alone. Furthermore, a removal efficiency of 70% was observed for D 4, showing that the addition of an oil fraction to a water system improves the absorption of VMS. These results show that VMS absorption into oils could be a promising way to achieve their abatement.

  19. Design principles for single standing nanowire solar cells: going beyond the planar efficiency limits.

    PubMed

    Zeng, Yang; Ye, Qinghao; Shen, Wenzhong

    2014-05-09

    Semiconductor nanowires (NWs) have long been used in photovoltaic applications but restricted to approaching the fundamental efficiency limits of the planar devices with less material. However, recent researches on standing NWs have started to reveal their potential of surpassing these limits when their unique optical property is utilized in novel manners. Here, we present a theoretical guideline for maximizing the conversion efficiency of a single standing NW cell based on a detailed study of its optical absorption mechanism. Under normal incidence, a standing NW behaves as a dielectric resonator antenna, and its optical cross-section shows its maximum when the lowest hybrid mode (HE11δ) is excited along with the presence of a back-reflector. The promotion of the cell efficiency beyond the planar limits is attributed to two effects: the built-in concentration caused by the enlarged optical cross-section, and the shifting of the absorption front resulted from the excited mode profile. By choosing an optimal NW radius to support the HE11δ mode within the main absorption spectrum, we demonstrate a relative conversion-efficiency enhancement of 33% above the planar cell limit on the exemplary a-Si solar cells. This work has provided a new basis for designing and analyzing standing NW based solar cells.

  20. Design principles for single standing nanowire solar cells: going beyond the planar efficiency limits

    PubMed Central

    Zeng, Yang; Ye, Qinghao; Shen, Wenzhong

    2014-01-01

    Semiconductor nanowires (NWs) have long been used in photovoltaic applications but restricted to approaching the fundamental efficiency limits of the planar devices with less material. However, recent researches on standing NWs have started to reveal their potential of surpassing these limits when their unique optical property is utilized in novel manners. Here, we present a theoretical guideline for maximizing the conversion efficiency of a single standing NW cell based on a detailed study of its optical absorption mechanism. Under normal incidence, a standing NW behaves as a dielectric resonator antenna, and its optical cross-section shows its maximum when the lowest hybrid mode (HE11δ) is excited along with the presence of a back-reflector. The promotion of the cell efficiency beyond the planar limits is attributed to two effects: the built-in concentration caused by the enlarged optical cross-section, and the shifting of the absorption front resulted from the excited mode profile. By choosing an optimal NW radius to support the HE11δ mode within the main absorption spectrum, we demonstrate a relative conversion-efficiency enhancement of 33% above the planar cell limit on the exemplary a-Si solar cells. This work has provided a new basis for designing and analyzing standing NW based solar cells. PMID:24810591

  1. Impact of one-dimensional photonic crystal back reflector in thin-film c-Si solar cells on efficiency

    NASA Astrophysics Data System (ADS)

    Jalali, Tahmineh

    2018-05-01

    In this work, the effect of one-dimensional photonic crystal on optical absorption, which is implemented at the back side of thin-film crystalline silicon (c-Si) solar cells, is extensively discussed. The proposed structure acts as a Bragg reflector which reflects back light to the active layer as well as nanograting which couples the incident light to enhance optical absorption. To understand the optical mechanisms responsible for the enhancement of optical absorption, quantum efficiency and current density for all structures are calculated and the effect of influential parameters, such as grating period is investigated. The results confirm that our proposed structure have a great deal for substantial efficiency enhancement in a broad range from 400 to 1100 nm.

  2. Imaging efficiency of an X-ray contrast agent-incorporated polymeric microparticle.

    PubMed

    Ahn, Sungsook; Jung, Sung Yong; Lee, Jin Pyung; Lee, Sang Joon

    2011-01-01

    Biocompatible polymeric encapsulants have been widely used as a delivery vehicle for a variety of drugs and imaging agents. In this study, X-ray contrast agent (iopamidol) is encapsulated into a polymeric microparticle (polyvinyl alcohol) as a particulate flow tracer in synchrotron X-ray imaging system. The physical properties of the designed microparticles are investigated and correlated with enhancement in the imaging efficiency by experimental observation and theoretical interpretation. The X-ray absorption ability of the designed microparticle is assessed by Beer-Lambert-Bouguer law. Particle size, either in dried state or in solvent, primarily dominates the X-ray absorption ability under the given condition, thus affecting imaging efficiency of the designed X-ray contrast flow tracers. Copyright © 2011 John Wiley & Sons, Ltd.

  3. A giant enhancement of multiphoton absorption in single-layer molybdenum disulfide

    NASA Astrophysics Data System (ADS)

    Zhou, Feng; Ji, Wei

    Identifying light absorption mechanisms in nanoscale materials, which are more efficient than those observed in bulk semiconductors, are of paramount importance to next-generation, infrared photo-detection. Here, we report considerable enhancement of degenerate two-photon absorption (2PA) and three-photon absorption (3PA) through two-dimensional (2D) excitonic effects in single-layer molybdenum disulfide (1L-MoS2) . We theoretically predict that both degenerate 2PA and 3PA coefficients of 1L-MoS2 are enhanced by 10-1000 times in the near-infrared (NIR), as compared with those of bulk semiconductors. Our theoretical prediction is validated by measuring photocurrents induced by 2PA or 3PA in a 1L-MoS2 photo-detector at room temperature where excitons in the immediate vicinity of the bandgap are transferred to the conduction band by a very small amount of thermal energy and dissociated under an external electric field. Our finding lays theoretical foundation and provides experimental evidence for developing sensitive infrared multiphoton detectors for nano-photonics. This work was supported by National University of Singapore through a research Grant: R144-000-327-112.

  4. 9.0% power conversion efficiency from ternary all-polymer solar cells

    DOE PAGES

    Li, Zhaojun; Xu, Xiaofeng; Zhang, Wei; ...

    2017-01-01

    High-performance ternary all-polymer solar cells with outstanding efficiency of 9.0% are realized by incorporating two donor and one acceptor polymers with complementary absorption and proper energy level alignment.

  5. Lightweight, Mesoporous, and Highly Absorptive All-Nanofiber Aerogel for Efficient Solar Steam Generation.

    PubMed

    Jiang, Feng; Liu, He; Li, Yiju; Kuang, Yudi; Xu, Xu; Chen, Chaoji; Huang, Hao; Jia, Chao; Zhao, Xinpeng; Hitz, Emily; Zhou, Yubing; Yang, Ronggui; Cui, Lifeng; Hu, Liangbing

    2018-01-10

    The global fresh water shortage has driven enormous endeavors in seawater desalination and wastewater purification; among these, solar steam generation is effective in extracting fresh water by efficient utilization of naturally abundant solar energy. For solar steam generation, the primary focus is to design new materials that are biodegradable, sustainable, of low cost, and have high solar steam generation efficiency. Here, we designed a bilayer aerogel structure employing naturally abundant cellulose nanofibrils (CNFs) as basic building blocks to achieve sustainability and biodegradability as well as employing a carbon nanotube (CNT) layer for efficient solar utilization with over 97.5% of light absorbance from 300 to 1200 nm wavelength. The ultralow density (0.0096 g/cm 3 ) of the aerogel ensures that minimal material is required, reducing the production cost while at the same time satisfying the water transport and thermal-insulation requirements due to its highly porous structure (99.4% porosity). Owing to its rationally designed structure and thermal-regulation performance, the bilayer CNF-CNT aerogel exhibits a high solar-energy conversion efficiency of 76.3% and 1.11 kg m -2 h -1 at 1 kW m -2 (1 Sun) solar irradiation, comparable or even higher than most of the reported solar steam generation devices. Therefore, the all-nanofiber aerogel presents a new route for designing biodegradable, sustainable, and scalable solar steam generation devices with superb performance.

  6. Highly efficient flexible piezoelectric nanogenerator and femtosecond two-photon absorption properties of nonlinear lithium niobate nanowires

    NASA Astrophysics Data System (ADS)

    Gupta, Manoj Kumar; Aneesh, Janardhanakurup; Yadav, Rajesh; Adarsh, K. V.; Kim, Sang-Woo

    2017-05-01

    We present a high performance flexible piezoelectric nanogenerator (NG) device based on the hydrothermally grown lead-free piezoelectric lithium niobate (LiNbO3) nanowires (NWs) for scavenging mechanical energies. The non-linear optical coefficient and optical limiting properties of LiNbO3 were analyzed using femtosecond laser pulse assisted two photon absorption techniques for the first time. Further, a flexible hybrid type NG using a composite structure of the polydimethylsiloxane polymer and LiNbO3 NWs was fabricated, and their piezoelectric output signals were measured. A large output voltage of ˜4.0 V and a recordable large current density of about 1.5 μA cm-2 were obtained under the cyclic compressive force of 1 kgf. A subsequent UV-Vis analysis of the as-prepared sample provides a remarkable increase in the optical band gap (UV absorption cut-off, ˜251 nm) due to the nanoscale size effect. The high piezoelectric output voltage and current are discussed in terms of large band gap, significant nonlinear optical response, and electric dipole alignments under poling effects. Such high performance and unique optical properties of LiNbO3 show its great potential towards various next generation smart electronic applications and self-powered optoelectronic devices.

  7. Energy absorption capabilities of composite sandwich panels under blast loads

    NASA Astrophysics Data System (ADS)

    Sankar Ray, Tirtha

    , ET) was suggested to compare energy absorption capabilities of the structures under blast loading. In addition, AEweb/ET (where AEweb is the energy absorbed by the middle core) was also employed to evaluate the energy absorption contribution from the web. Taking advantage of FEA and the simplified analytical model, the influences of material properties as well as core architectures and geometries on energy absorption capabilities (quantified by AET/ ET and AEweb/E T) were investigated through parametric studies. Results from the material property investigation indicated that density of the front face sheet and strength were most influential on the energy absorption capability of the composite sandwich panels under blast loading. The study to investigate the potential effectiveness of energy absorbed via inelastic deformation compared to energy absorbed via progressive failure indicated that for practical applications (where the position of bomb is usually unknown and the panel is designed to be the same anywhere), the energy absorption via inelastic deformation is the more efficient approach. Regarding the geometric optimization, it was found that a core architecture consisting of vertically-oriented webs was ideal. The optimum values for these parameters can be generally described as those which cause the most inelasticity, but not failure, of the face sheets and webs.

  8. Sequential microwave superheated water extraction of mannans from spent coffee grounds.

    PubMed

    Passos, Cláudia P; Moreira, Ana S P; Domingues, M Rosário M; Evtuguin, Dmitry V; Coimbra, Manuel A

    2014-03-15

    The feasibility of using sequential microwave superheated water extraction (MAE) for the recovery of mannans from spent coffee grounds (SCG) was studied. Due to the high contents of mannose still present in the SCG residue left after two consecutive MAE, the unextracted material was re-suspended in water and submitted to a third microwave irradiation (MAE3) at 200 °C for 3 min. With MAE3, mannose recovery achieved 48%, increasing to 56% by MAE4, and reaching a maximum of 69% with MAE5. Glycosidic-linkage analysis showed that in MAE3 mainly galactomannans were recovered, while debranched galactomannans were recovered with MAE4 and MAE5. With increasing the number of extractions, the average degree of polymerization of the mannans decreased, as observed by size-exclusion chromatography and by methylation analysis. Scanning electron microscopy images showed a decrease on cell walls thickness. After final MAE5, the remaining un-extracted insoluble material, representing 22% of the initial SCG, was composed mainly by cellulose (84%). Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Nonlinear absorption in biological tissue for high intensity focused ultrasound.

    PubMed

    Liu, Xiaozhou; Li, Junlun; Gong, Xiufen; Zhang, Dong

    2006-12-22

    In recent years the propagation of the high intensity focused ultrasound (HIFU) in biological tissue is an interesting area due to its potential applications in non-invasive treatment of disease. The base principle of these applications is the heat effect generated by ultrasound absorption. In order to control therapeutic efficiency, it is important to evaluate the heat generation in biological tissue irradiated by ultrasound. In his paper, based on the Khokhlov-Zabolotkaya-Kuznetsov (KZK) equation in frequency-domain, the numerical simulations of nonlinear absorption in biological tissues for high intensity focused ultrasound are performed. We find that ultrasound thermal transfer effect will be enhanced with the increasing of initial acoustic intensity due to the high harmonic generation. The concept of extra absorption factor is introduced to describe nonlinear absorption in biological tissue for HIFU. The theoretical results show that the heat deposition induced by the nonlinear theory can be nearly two times as large as that predicated by linear theory. Then, the influence of the diffraction effect on the position of the focus in HIFU is investigated. It is shown that the sound focus moves toward the transducer compared with the geometry focus because of the diffraction of the sound wave. The position of the maximum heat deposition is shifted to the geometry focus with the increase of initial acoustic intensity because the high harmonics are less diffraction. Finally, the temperature in the porcine fat tissue changing with the time is predicated by Pennes' equation and the experimental results verify the nonlinear theoretical prediction.

  10. Metal-core/semiconductor-shell nanocones for broadband solar absorption enhancement.

    PubMed

    Zhou, Lin; Yu, Xiaoqiang; Zhu, Jia

    2014-02-12

    Nanostructure-based photovoltaic devices have exhibited several advantages, such as reduced reflection, extraordinary light trapping, and so forth. In particular, semiconductor nanostructures provide optical modes that have strong dependence on the size and geometry. Metallic nanostructures also attract a lot of attention because of the appealing plasmonic effect on the near-field enhancement. In this study, we propose a novel design, the metal-core/semiconductor-shell nanocones with the core radius varying in a linearly gradient style. With a thin layer of semiconductor absorber coated on a metallic cone, such a design can lead to significant and broadband absorption enhancement across the entire visible and near-infrared solar spectrum. As an example of demonstration, a layer of 16 nm thick crystalline silicon (c-Si) coated on a silver nanocone can absorb 27% of standard solar radiation across a broad spectral range of 300-1100 nm, which is equivalent to a 700 nm thick flat c-Si film. Therefore, the absorption enhancement factor approaching the Yablonovitch limit is achieved with this design. The significant absorption enhancement can be ascribed to three types of optical modes, that is, Fabry-Perot modes, plasmonic modes, and hybrid modes that combine the features of the previous two. In addition, the unique nanocone geometry enables the linearly gradient radius of the semiconductor shell, which can support multiple optical resonances, critical for the broadband absorption. Our design may find general usage as elements for the low cost, high efficiency solar conversion and water-splitting devices.

  11. Time-dependent efficiency measurements of polymer solar cells with dye additives: unexpected initial increase of efficiency

    NASA Astrophysics Data System (ADS)

    Bandaccari, Kyle J.; Chesmore, Grace E.; Bugaj, Mitchel; Valverde, Parisa Tajalli-Tehrani; Barber, Richard P.; McNelis, Brian J.

    2018-04-01

    We report the effects of the addition of two azo-dye additives on the time-dependent efficiency of polymer solar cells. Although the maximum efficiencies of devices containing different amounts of dye do not vary greatly over the selected concentration range, the time dependence results reveal a surprising initial increase in efficiency in some samples. We observe this effect to be correlated with a leakage current, although a specific mechanism is not yet identified. We also present the measured lifetimes of these solar cells, and find that variations in dye concentrations produce a small effect at most. Characterization of the bulk heterojunction layer (active layer) morphology using atomic-force microscope (AFM) imaging reveals reordering patterns which suggest that the primary effects of the dyes arise via structural, not absorptive, characteristics.

  12. Iron absorption from Southeast Asian diets. II. Role of various factors that might explain low absorption.

    PubMed

    Hallberg, L; Björn-Rasmussen, E; Rossander, L; Suwanik, R

    1977-04-01

    Previously reported levels of iron absorption from common Southeast Asian meals composed of rice, vegetables, and spices were too low to be consistent with the known prevalence of iron deficiency. In the present paper the cause of the low absorption was systematically sought. Variables investigated comprised methodological errors, factors in the diet such as certain foodstuffs, or contaminants inhibiting the absorption and characteristics of the subjects accompanied by malabsorption of dietary iron. The latter was excluded by comparing the absorption from both wheat rolls and a composit rice meal in Thai and Swedish women using the absorption of a small dose of ferrous ascorbate as a common basis of comparison. Two main factors were identified as causing the low absorption in the previous studies: the homogenization of the labeled meals before serving and the use of rice flour instead of rice. Iron absorption from nonhomogenized meals of identical composition as studied previously was many times higher (on an average 0.16 mg) and was consistent with the actual prevalence of iron deficiency in lower socioeconomic groups of Thais mainly consuming the simple meals studied. Recent modifications of the method to measure nonheme iron absorption from composite meals have thus not only made the determination simpler but also more accurate.

  13. Examination of the Measurement of Absorption Using the Reverberant Room Method for Highly Absorptive Acoustic Foam

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.; Chris Nottoli; Eric Wolfram

    2015-01-01

    The absorption coefficient for material specimens are needed to quantify the expected acoustic performance of that material in its actual usage and environment. The ASTM C423-09a standard, "Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberant Room Method" is often used to measure the absorption coefficient of material test specimens. This method has its basics in the Sabine formula. Although widely used, the interpretation of these measurements are a topic of interest. For example, in certain cases the measured Sabine absorption coefficients are greater than 1.0 for highly absorptive materials. This is often attributed to the diffraction edge effect phenomenon. An investigative test program to measure the absorption properties of highly absorbent melamine foam has been performed at the Riverbank Acoustical Laboratories. This paper will present and discuss the test results relating to the effect of the test materials' surface area, thickness and edge sealing conditions. A follow-on paper is envisioned that will present and discuss the results relating to the spacing between multiple piece specimens, and the mounting condition of the test specimen.

  14. Infrared reduction, an efficient method to control the non-linear optical property of graphene oxide in femtosecond regime

    NASA Astrophysics Data System (ADS)

    Bhattacharya, S.; Maiti, R.; Saha, S.; Das, A. C.; Mondal, S.; Ray, S. K.; Bhaktha, S. B. N.; Datta, P. K.

    2016-04-01

    Graphene Oxide (GO) has been prepared by modified Hummers method and it has been reduced using an IR bulb (800-2000 nm). Both as grown GO and reduced graphene oxide (RGO) have been characterized using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Raman spectra shows well documented Dband and G-band for both the samples while blue shift of G-band confirms chemical functionalization of graphene with different oxygen functional group. The XPS result shows that the as-prepared GO contains 52% of sp2 hybridized carbon due to the C=C bonds and 33% of carbon atoms due to the C-O bonds. As for RGO, increment of the atomic % of the sp2 hybridized carbon atom to 83% and rapid decrease in atomic % of C=O bonds confirm an efficient reduction with infrared radiation. UV-Visible absorption spectrum also confirms increment of conjugation with increased reduction. Non-linear optical properties of both GO and RGO are measured using single beam open aperture Z-Scan technique in femtosecond regime. Intensity dependent nonlinear phenomena are observed. Depending upon the intensity, both saturable absorption and two photon absorption contribute to the non-linearity of both the samples. Saturation dominates at low intensity (~ 127 GW/cm2) while two photon absorption become prominent at higher intensities (from 217 GW/cm2 to 302 GW/cm2). We have calculated the two-photon absorption co-efficient and saturation intensity for both the samples. The value of two photon absorption co-efficient (for GO~ 0.0022-0.0037 cm/GW and for RGO~ 0.0128-0.0143 cm/GW) and the saturation intensity (for GO~57 GW/cm2 and for RGO~ 194GW/cm2) is increased with reduction. Increase in two photon absorption coefficient with increasing intensity can also suggest that there may be multi-photon absorption is taking place.

  15. Closed vessel miniaturized microwave assisted chelating extraction for determination of trace metals in plant materials

    NASA Astrophysics Data System (ADS)

    Czarnecki, Sezin; Duering, Rolf-Alexander

    2013-04-01

    In recent years, the use of closed vessel microwave assisted extraction (MAE) for plant samples has shown increasing research interest which will probably substitute conventional procedures in the future due to their general disadvantages including consumption of time and solvents. The objective of this study was to demonstrate an innovative miniaturized closed vessel microwave assisted extraction (µMAE) method under the use of EDTA (µMAE-EDTA) to determine metal contents (Cd, Co, Cu, Mn, Ni, Pb, Zn) in plant samples (Lolio-Cynosuretum) by inductively coupled plasma-optical emission spectrometry (ICP-OES). Validation of the method was done by comparison of the results with another miniaturized closed vessel microwave HNO3 method (µMAE-H) and with two other macro scale MAE procedures (MAE-H and MAE-EDTA) which were applied by using a mixture of nitric acid (HNO3) and hydrogen peroxide (H2O2) (MAE-H) and EDTA (MAE-EDTA), respectively. The already established MAE-H method is taken into consideration as a reference validation MAE method for plant material. A conventional plant extraction (CE) method, based on dry ashing and dissolving of the plant material in HNO3, was used as a confidence comparative method. Certified plant reference materials (CRMs) were used for comparison of recovery rates from different extraction protocols. This allowed the validation of the applicability of the µMAE-EDTA procedure. For 36 real plant samples with triplicates each, µMAE-EDTA showed the same extraction yields as the MAE-H in the determination of Cd, Co, Cu, Mn, Ni, Pb, and Zn contents in plant samples. Analytical parameters in µMAE-EDTA should be further investigated and adapted for other metals of interest. By the reduction and elimination of the use of hazardous chemicals in environmental analysis and thus allowing a better understanding of metal distribution and accumulation process in plants and also the metal transfer from soil to plants and into the food chain, µMAE

  16. Flexible thin-film black gold membranes with ultrabroadband plasmonic nanofocusing for efficient solar vapour generation.

    PubMed

    Bae, Kyuyoung; Kang, Gumin; Cho, Suehyun K; Park, Wounjhang; Kim, Kyoungsik; Padilla, Willie J

    2015-12-14

    Solar steam generation has been achieved by surface plasmon heating with metallic nanoshells or nanoparticles, which have inherently narrow absorption bandwidth. For efficient light-to-heat conversion from a wider solar spectrum, we employ adiabatic plasmonic nanofocusing to attain both polarization-independent ultrabroadband light absorption and high plasmon dissipation loss. Here we demonstrate large area, flexible thin-film black gold membranes, which have multiscale structures of varying metallic nanoscale gaps (0-200 nm) as well as microscale funnel structures. The adiabatic nanofocusing of self-aggregated metallic nanowire bundle arrays produces average absorption of 91% at 400-2,500 nm and the microscale funnel structures lead to average reflection of 7% at 2.5-17 μm. This membrane allows heat localization within the few micrometre-thick layer and continuous water provision through micropores. We efficiently generate water vapour with solar thermal conversion efficiency up to 57% at 20 kW m(-2). This new structure has a variety of applications in solar energy harvesting, thermoplasmonics and related technologies.

  17. Flexible thin-film black gold membranes with ultrabroadband plasmonic nanofocusing for efficient solar vapour generation

    PubMed Central

    Bae, Kyuyoung; Kang, Gumin; Cho, Suehyun K.; Park, Wounjhang; Kim, Kyoungsik; Padilla, Willie J.

    2015-01-01

    Solar steam generation has been achieved by surface plasmon heating with metallic nanoshells or nanoparticles, which have inherently narrow absorption bandwidth. For efficient light-to-heat conversion from a wider solar spectrum, we employ adiabatic plasmonic nanofocusing to attain both polarization-independent ultrabroadband light absorption and high plasmon dissipation loss. Here we demonstrate large area, flexible thin-film black gold membranes, which have multiscale structures of varying metallic nanoscale gaps (0–200 nm) as well as microscale funnel structures. The adiabatic nanofocusing of self-aggregated metallic nanowire bundle arrays produces average absorption of 91% at 400–2,500 nm and the microscale funnel structures lead to average reflection of 7% at 2.5–17 μm. This membrane allows heat localization within the few micrometre-thick layer and continuous water provision through micropores. We efficiently generate water vapour with solar thermal conversion efficiency up to 57% at 20 kW m−2. This new structure has a variety of applications in solar energy harvesting, thermoplasmonics and related technologies. PMID:26657535

  18. Method for improving dissolution efficiency in gas-absorption and liquid extraction processes

    DOEpatents

    Kanak, Brant E.; Stephenson, Michael J.

    1981-01-01

    This invention is a method for improving dissolution efficiency in processes in which a feed fluid is introduced to a zone where it is contacted with a liquid solvent for preferentially removing a component of the feed and where part of the solvent so contacted undergoes transfer into the feed fluid to saturate the same. It has been found that such transfer significantly impairs dissolution efficiency. In accordance with the invention, an amount of the above-mentioned solvent is added to the feed fluid being introduced to the contact zone, the solvent being added in an amount sufficient to effect reduction or elimination of the above-mentioned transfer. Preferably, the solvent is added to the feed fluid in an amount saturating or supersaturating the feed fluid under the conditions prevailing in the contact zone.

  19. Improved hopcalite procedure for the determination of mercury vapor in air by flameless atomic absorption.

    PubMed

    Rathje, A O; Marcero, D H

    1976-05-01

    Mercury vapor is efficiently trapped from air by passage through a small glass tube filled with hopcalite. The hopcalite and adsorbed mercury are dissolved in a mixture of nitric and hydrochloric acids. Solution is rapid and complete, with no loss of mercury. Analysis is completed by flameless atomic absorption.

  20. Unusual continuous dual absorption peaks in Ca-doped BiFeO3 nanostructures for broadened microwave absorption

    NASA Astrophysics Data System (ADS)

    Li, Zhong-Jun; Hou, Zhi-Ling; Song, Wei-Li; Liu, Xing-Da; Cao, Wen-Qiang; Shao, Xiao-Hong; Cao, Mao-Sheng

    2016-05-01

    Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3 nanoparticles via Ca doping, with the purpose of tailoring the phase boundary. Upon Ca-substitution, the co-existence of both R3c and P4mm phases has been confirmed to massively enhance both dielectric and magnetic properties via manipulating the phase boundary and the destruction of the spiral spin structure. Unlike the commonly reported magnetic/dielectric hybrid microwave absorption composites, Bi0.95Ca0.05FeO3 has been found to deliver unusual continuous dual absorption peaks at a small thickness (1.56 mm), which has remarkably broadened the effective absorption bandwidth (8.7-12.1 GHz). The fundamental mechanisms based on the phase boundary engineering have been discussed, suggesting a novel platform for designing advanced multiferroic materials with wide applications.Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3

  1. Counterflow absorber for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    An air-cooled, vertical tube absorber for an absorption refrigeration system is disclosed. Strong absorbent solution is supplied to the top of the absorber and refrigerant vapor is supplied to the bottom of the absorber to create a direct counterflow of refrigerant vapor and absorbent solution in the absorber. The refrigeration system is designed so that the volume flow rate of refrigerant vapor in the tubes of the absorber is sufficient to create a substantially direct counterflow along the entire length of each tube in the absorber. This provides several advantages for the absorber such as higher efficiency and improved heat transfer characteristics, and allows improved purging of non-condensibles from the absorber.

  2. Biological optimization systems for enhancing photosynthetic efficiency and methods of use

    DOEpatents

    Hunt, Ryan W.; Chinnasamy, Senthil; Das, Keshav C.; de Mattos, Erico Rolim

    2012-11-06

    Biological optimization systems for enhancing photosynthetic efficiency and methods of use. Specifically, methods for enhancing photosynthetic efficiency including applying pulsed light to a photosynthetic organism, using a chlorophyll fluorescence feedback control system to determine one or more photosynthetic efficiency parameters, and adjusting one or more of the photosynthetic efficiency parameters to drive the photosynthesis by the delivery of an amount of light to optimize light absorption of the photosynthetic organism while providing enough dark time between light pulses to prevent oversaturation of the chlorophyll reaction centers are disclosed.

  3. Methodological variations and their effects on reported medication administration error rates.

    PubMed

    McLeod, Monsey Chan; Barber, Nick; Franklin, Bryony Dean

    2013-04-01

    Medication administration errors (MAEs) are a problem, yet methodological variation between studies presents a potential barrier to understanding how best to increase safety. Using the UK as a case-study, we systematically summarised methodological variations in MAE studies, and their effects on reported MAE rates. Nine healthcare databases were searched for quantitative observational MAE studies in UK hospitals. Methodological variations were analysed and meta-analysis of MAE rates performed using studies that used the same definitions. Odds ratios (OR) were calculated to compare MAE rates between intravenous (IV) and non-IV doses, and between paediatric and adult doses. We identified 16 unique studies reporting three MAE definitions, 44 MAE subcategories and four different denominators. Overall adult MAE rates were 5.6% of a total of 21 533 non-IV opportunities for error (OE) (95% CI 4.6% to 6.7%) and 35% of a total of 154 IV OEs (95% CI 2% to 68%). MAEs were five times more likely in IV than non-IV doses (pooled OR 5.1; 95% CI 3.5 to 7.5). Including timing errors of ±30 min increased the MAE rate from 27% to 69% of 320 IV doses in one study. Five studies were unclear as to whether the denominator included dose omissions; omissions accounted for 0%-13% of IV doses and 1.8%-5.1% of non-IV doses. Wide methodological variations exist even within one country, some with significant effects on reported MAE rates. We have made recommendations for future MAE studies; these may be applied both within and outside the UK.

  4. Robust nonfullerene solar cells approaching unity external quantum efficiency enabled by suppression of geminate recombination.

    PubMed

    Baran, Derya; Gasparini, Nicola; Wadsworth, Andrew; Tan, Ching Hong; Wehbe, Nimer; Song, Xin; Hamid, Zeinab; Zhang, Weimin; Neophytou, Marios; Kirchartz, Thomas; Brabec, Christoph J; Durrant, James R; McCulloch, Iain

    2018-05-25

    Nonfullerene solar cells have increased their efficiencies up to 13%, yet quantum efficiencies are still limited to 80%. Here we report efficient nonfullerene solar cells with quantum efficiencies approaching unity. This is achieved with overlapping absorption bands of donor and acceptor that increases the photon absorption strength in the range from about 570 to 700 nm, thus, almost all incident photons are absorbed in the active layer. The charges generated are found to dissociate with negligible geminate recombination losses resulting in a short-circuit current density of 20 mA cm -2 along with open-circuit voltages >1 V, which is remarkable for a 1.6 eV bandgap system. Most importantly, the unique nano-morphology of the donor:acceptor blend results in a substantially improved stability under illumination. Understanding the efficient charge separation in nonfullerene acceptors can pave the way to robust and recombination-free organic solar cells.

  5. Broadband perfect infrared absorption by tuning epsilon-near-zero and epsilon-near-pole resonances of multilayer ITO nanowires.

    PubMed

    Zhou, Kun; Cheng, Qiang; Song, Jinlin; Lu, Lu; Jia, Zhihao; Li, Junwei

    2018-01-01

    We numerically investigate the broadband perfect infrared absorption by tuning epsilon-near-zero (ENZ) and epsilon-near-pole (ENP) resonances of multilayer indium tin oxide nanowires (ITO NWs). The monolayer ITO NWs array shows intensive absorption at ENZ and ENP wavelengths for p polarization, while only at the ENP wavelength for s polarization. Moreover, the ENP resonances are almost omnidirectional and the ENZ resonances are angularly dependent. Therefore, the absorption bandwidth is broader for p polarization than that for s polarization when polarized waves are incident obliquely. The ENZ resonances can be tuned by altering the doping concentration and volume filling factor of ITO NWs. However, the ENP resonances only can be tuned by changing the doping concentration of ITO NWs, and volume filling factor impacts little on the ENP resonances. Based on the strong absorption properties of each layer at their own ENP and ENZ resonances, the tuned absorption of the bilayer ITO NWs with the different doping concentrations can be broader and stronger. Furthermore, multilayer ITO NWs can achieve broadband perfect absorption by controlling the doping concentration, volume filling factor, and length of the NWs in each layer. This study has the potential to apply to applications requiring efficient absorption and energy conversion.

  6. Wood-Graphene Oxide Composite for Highly Efficient Solar Steam Generation and Desalination.

    PubMed

    Liu, Keng-Ku; Jiang, Qisheng; Tadepalli, Sirimuvva; Raliya, Ramesh; Biswas, Pratim; Naik, Rajesh R; Singamaneni, Srikanth

    2017-03-01

    Solar steam generation is a highly promising technology for harvesting solar energy, desalination and water purification. We introduce a novel bilayered structure composed of wood and graphene oxide (GO) for highly efficient solar steam generation. The GO layer deposited on the microporous wood provides broad optical absorption and high photothermal conversion resulting in rapid increase in the temperature at the liquid surface. On the other hand, wood serves as a thermal insulator to confine the photothermal heat to the evaporative surface and to facilitate the efficient transport of water from the bulk to the photothermally active space. Owing to the tailored bilayer structure and the optimal thermo-optical properties of the individual components, the wood-GO composite structure exhibited a solar thermal efficiency of ∼83% under simulated solar excitation at a power density of 12 kW/m 2 . The novel composite structure demonstrated here is highly scalable and cost-efficient, making it an attractive material for various applications involving large light absorption, photothermal conversion and heat localization.

  7. SO2 absorption in EmimCl-TEG deep eutectic solvents.

    PubMed

    Yang, Dezhong; Zhang, Shaoze; Jiang, De-En; Dai, Sheng

    2018-06-06

    Deep eutectic solvents (DESs) based on 1-ethyl-3-methylimidazolium chloride (EmimCl) and triethylene glycol (TEG) with different molar ratios (from 6 : 1 to 1 : 1) were prepared. FTIR and theoretical calculation indicated that the C2-H on the imidazolium ring form hydrogen bonds with the hydroxyl group rather than the ether O atom of the TEG. The EmimCl-TEG DESs can efficiently capture SO2; in particular, EmimCl-TEG (6 : 1) can capture 0.54 g SO2 per gram of solvent at 0.10 atm and 20 °C, the highest absorption amount for DESs under the same conditions. Theoretical calculation showed that the high SO2 absorption capacity was mainly due to the strong charge-transfer interaction between SO2 and the anion Cl-. Moreover, SO2 desorption in the DESs can be controlled by tuning the interaction between EmimCl and TEG, and the DESs can be cycled many times.

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

    PubMed

    Thakur, Pooja; Tan, Bo; Venkatakrishnan, Krishnan

    2015-10-19

    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.

  9. Absorption fluids data survey

    NASA Astrophysics Data System (ADS)

    Macriss, R. A.; Zawacki, T. S.

    Development of improved data for the thermodynamic, transport and physical properties of absorption fluids were studied. A specific objective of this phase of the study is to compile, catalog and coarse screen the available US data of known absorption fluid systems and publish it as a first edition document to be distributed to manufacturers, researchers and others active in absorption heat pump activities. The methodology and findings of the compilation, cataloguing and coarse screening of the available US data on absorption fluid properties and presents current status and future work on this project are summarized. Both in house file and literature searches were undertaken to obtain available US publications with pertinent physical, thermodynamic and transport properties data for absorption fluids. Cross checks of literature searches were also made, using available published bibliographies and literature review articles, to eliminate secondary sources for the data and include only original sources and manuscripts. The properties of these fluids relate to the liquid and/or vapor state, as encountered in normal operation of absorption equipment employing such fluids, and to the crystallization boundary of the liquid phase, where applicable. The actual data were systematically classified according to the type of fluid and property, as well as temperature, pressure and concentration ranges over which data were available. Data were sought for 14 different properties: Vapor-Liquid Equilibria, Crystallization Temperature, Corrosion Characteristics, Heat of Mixing, Liquid-Phase-Densities, Vapor-Liquid-Phase Enthalpies, Specific Heat, Stability, Viscosity, Mass Transfer Rate, Heat Transfer Rate, Thermal Conductivity, Flammability, and Toxicity.

  10. Tunneling induced absorption with competing Nonlinearities

    PubMed Central

    Peng, Yandong; Yang, Aihong; Xu, Yan; Wang, Peng; Yu, Yang; Guo, Hongju; Ren, Tingqi

    2016-01-01

    We investigate tunneling induced nonlinear absorption phenomena in a coupled quantum-dot system. Resonant tunneling causes constructive interference in the nonlinear absorption that leads to an increase of more than an order of magnitude over the maximum absorption in a coupled quantum dot system without tunneling. Resonant tunneling also leads to a narrowing of the linewidth of the absorption peak to a sublinewidth level. Analytical expressions show that the enhanced nonlinear absorption is largely due to the fifth-order nonlinear term. Competition between third- and fifth-order nonlinearities leads to an anomalous dispersion of the total susceptibility. PMID:27958303

  11. Tunneling induced absorption with competing Nonlinearities.

    PubMed

    Peng, Yandong; Yang, Aihong; Xu, Yan; Wang, Peng; Yu, Yang; Guo, Hongju; Ren, Tingqi

    2016-12-13

    We investigate tunneling induced nonlinear absorption phenomena in a coupled quantum-dot system. Resonant tunneling causes constructive interference in the nonlinear absorption that leads to an increase of more than an order of magnitude over the maximum absorption in a coupled quantum dot system without tunneling. Resonant tunneling also leads to a narrowing of the linewidth of the absorption peak to a sublinewidth level. Analytical expressions show that the enhanced nonlinear absorption is largely due to the fifth-order nonlinear term. Competition between third- and fifth-order nonlinearities leads to an anomalous dispersion of the total susceptibility.

  12. Effects of temperature, algae biomass and ambient nutrient on the absorption of dissolved nitrogen and phosphate by Rhodophyte Gracilaria asiatica

    NASA Astrophysics Data System (ADS)

    Du, Rongbin; Liu, Liming; Wang, Aimin; Wang, Yongqiang

    2013-03-01

    Gracilaria asiatica, being highly efficient in nutrient absorption, is cultivated in sea cucumber ponds to remove nutrients such as nitrogen and phosphate. It was cultured in a laboratory simulating field conditions, and its nutrient absorption was measured to evaluate effects of environmental conditions. Ammonia nitrogen (AN), nitrate nitrogen (NN), total inorganic nitrogen (TIN), and soluble reactive phosphorus (SRP) uptake rate and removal efficiency were determined in a 4×2 factorial design experiment in water temperatures ( T) at 15°C and 25°C, algae biomass (AB) at 0.5 g/L and 1.0 g/L, total inorganic nitrogen (TIN) at 30 μmol/L and 60 μmol/L, and soluble reactive phosphorus (SRP) at 3 and 6 μmol/L. AB and ambient TIN or SRP levels significantly affected uptake rate and removal efficiency of AN, NN, TIN, and SRP ( P< 0.001). G. asiatica in AB of 0.5 g/L showed higher uptake rate and lower removal efficiency relative to that with AB of 1.0 g/L. Nitrogen and phosphorus uptake rate rose with increasing ambient nutrient concentrations; nutrient removal efficiency decreased at higher environmental nutrient concentrations. The algae preferred to absorb AN to NN. Uptake rates of AN, NN, and SRP were significantly affected by temperature ( P < 0.001); uptake rate was higher for the 25°C group than for the 15°C group at the initial experiment stage. Only the removal efficiency of AN and SRP showed a significant difference between the two temperature groups ( P< 0.01). The four factors had significant interactive effects on absorption of N and P, implying that G. asiatica has great bioremedial potential in sea cucumber culture ponds.

  13. Solar absorption surface panel

    DOEpatents

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  14. Nd/sup 3 +/ fluorescence quantum-efficiency measurements with photoacoustics

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

    Rosencwaig, A.; Hildum, E.A.

    1981-04-01

    We have investigated the use of photoacoustic techniques for obtaining absolute values of fluorescence quantum efficiencies in lightly doped Nd/sup 3 +/ laser materials. We have found that surface absorptions play an important role in gas-microphone measurements, and that thermal profiles are important in piezoelectric measurements. We have obtained fluorescence quantum efficiencies for Nd/sup 3 +/ in yttrium aluminum garnet, and in silicate and borate glasses that are in good agreement with lifetime measurements and Judd-Ofelt calculations.

  15. Organic fertilizer application increases the soil respiration and net ecosystem carbon dioxide absorption of paddy fields under water-saving irrigation.

    PubMed

    Yang, Shihong; Xiao, Ya Nan; Xu, Junzeng

    2018-04-01

    Quantifying carbon sequestration in paddy soil is necessary to understand the effect of agricultural practices on carbon cycles. The objective of this study was to assess the effect of organic fertilizer addition (MF) on the soil respiration and net ecosystem carbon dioxide (CO 2 ) absorption of paddy fields under water-saving irrigation (CI) in the Taihu Lake Region of China during the 2014 and 2015 rice-growing seasons. Compared with the traditional fertilizer and water management (FC), the joint regulation of CI and MF (CM) significantly increased the rice yields and irrigation water use efficiencies of paddy fields by 4.02~5.08 and 83.54~109.97% (p < 0.05). The effects of organic fertilizer addition on soil respiration and net ecosystem CO 2 absorption rates showed inter-annual differences. CM paddy fields showed a higher soil respiration and net CO 2 absorption rates during some periods of the rice growth stage in the first year and during most periods of the rice growth stage in the second year. These fields also had significantly higher total CO 2 emission through soil respiration (total R soil ) and total net CO 2 absorption compared with FC paddy fields (p < 0.05). The total R soil and net ecosystem CO 2 absorption of CM paddy fields were 67.39~91.55 and 129.41~113.75 mol m -2 , which were 27.66~135.52 and 12.96~31.66% higher than those of FC paddy fields. The interaction between water and fertilizer management had significant effects on total net ecosystem CO 2 absorption. The frequent alternate wet-dry cycles of CI paddy fields increased the soil respiration and reduced the net CO 2 absorption. Organic fertilizer promoted the soil respiration of paddy soil but also increased its net CO 2 absorption and organic carbon content. Therefore, the joint regulation of water-saving irrigation and organic fertilizer is an effective measure for maintaining yield, increasing irrigation water use efficiency, mitigating CO 2 emission, and promoting paddy

  16. Research on the self-absorption corrections for PGNAA of large samples

    NASA Astrophysics Data System (ADS)

    Yang, Jian-Bo; Liu, Zhi; Chang, Kang; Li, Rui

    2017-02-01

    When a large sample is analysed with the prompt gamma neutron activation analysis (PGNAA) neutron self-shielding and gamma self-absorption affect the accuracy, the correction method for the detection efficiency of the relative H of each element in a large sample is described. The influences of the thickness and density of the cement samples on the H detection efficiency, as well as the impurities Fe2O3 and SiO2 on the prompt γ ray yield for each element in the cement samples, were studied. The phase functions for Ca, Fe, and Si on H with changes in sample thickness and density were provided to avoid complicated procedures for preparing the corresponding density or thickness scale for measuring samples under each density or thickness value and to present a simplified method for the measurement efficiency scale for prompt-gamma neutron activation analysis.

  17. Differential-optoacoustic absorption detector

    NASA Technical Reports Server (NTRS)

    Shumate, M. S.

    1977-01-01

    Two-cell spectrophone detects trace amounts of atmospheric pollutants by measuring absorption coefficients of gases with various laser sources. Device measures pressure difference between two tapered cells with differential manometer. Background signal is reduced by balanced window heating and balanced carrier gas absorption in two cells.

  18. Ultrafast X-Ray Absorption Spectroscopy of Isochorically Heated Warm Dense Matter

    NASA Astrophysics Data System (ADS)

    Engelhorn, Kyle Craig

    This dissertation will present a series of new tools, together with new techniques, focused on the understanding of warm and dense matter. We report on the development of a high time resolution and high detection efficiency x-ray camera. The camera is integrated with a short pulse laser and an x-ray beamline at the Advanced Light Source synchrotron. This provides an instrument for single shot, broadband x-ray absorption spectroscopy of warm and dense matter with 2 picosecond time resolution. Warm and dense matter is created by isochorically heating samples of known density with an ultrafast optical laser pulse, and X-ray absorption spectroscopy probes the unoccupied electronic density of states before the onset of hydrodynamic expansion and electron-ion equilibrium is reached. Measured spectra from a variety of materials are compared with first principle molecular dynamics and density functional theory calculations. In heated silicon dioxide spectra, two novel pre-edge features are observed, a peak below the band gap and absorption within the band gap, while a reduction was observed in the features above the edge. From consideration of the calculated spectra, the peak below the gap is attributed to valence electrons that have been promoted to the conduction band, the absorption within the gap is attributed to broken Si-O bonds, and the reduction above the edge is attributed to an elevated ionic temperature. In heated copper spectra, a time-dependent shift and broadening of the absorption edge are observed, consistent with and elevated electron temperature. The temporal evolution of the electronic temperature is accurately determined by fitting the measured spectra with calculated spectra. The electron-ion equilibration is studied with a two-temperature model. In heated nickel spectra, a shift of the absorption edge is observed. This shift is found to be inconsistent with calculated spectra and independent of incident laser fluence. A shift of the chemical potential

  19. Coupling continuous damage and debris fragmentation for energy absorption prediction by cfrp structures during crushing

    NASA Astrophysics Data System (ADS)

    Espinosa, Christine; Lachaud, Frédéric; Limido, Jérome; Lacome, Jean-Luc; Bisson, Antoine; Charlotte, Miguel

    2015-05-01

    Energy absorption during crushing is evaluated using a thermodynamic based continuum damage model inspired from the Matzenmiller-Lubliner-Taylors model. It was found that for crash-worthiness applications, it is necessary to couple the progressive ruin of the material to a representation of the matter openings and debris generation. Element kill technique (erosion) and/or cohesive elements are efficient but not predictive. A technique switching finite elements into discrete particles at rupture is used to create debris and accumulated mater during the crushing of the structure. Switching criteria are evaluated using the contribution of the different ruin modes in the damage evolution, energy absorption, and reaction force generation.

  20. Evaluation of Extraction and Degradation Methods to Obtain Chickpeasaponin B1 from Chickpea (Cicer arietinum L.).

    PubMed

    Cheng, Kun; Gao, Hua; Wang, Rong-Rong; Liu, Yang; Hou, Yu-Xue; Liu, Xiao-Hong; Liu, Kun; Wang, Wei

    2017-02-21

    The objective of this research is to implement extraction and degradation methods for the obtainment of 3- O -[α-l-rhamnopyranosyl-(1→2)-β-d-galactopyranosyl] soyasapogenol B (chickpeasaponin B1) from chickpea. The effects of microwave-assisted extraction (MAE) processing parameters-such as ethanol concentration, solvent/solid ratio, extraction temperature, microwave irradiation power, and irradiation time-were evaluated. Using 1g of material with 8 mL of 70% aqueous ethanol and an extraction time of 10 min at 70 °C under irradiation power 400W provided optimal extraction conditions. Compared with the conventional extraction techniques, including heat reflux extraction (HRE), Soxhlet extraction (SE), and ultrasonic extraction (UE), MAE produced higher extraction efficiency under a lower extraction time. DDMP (2,3-dihydro-2,5-dihydroxy-6-methyl-4 H -pyran-4-one) saponin can be degraded to structurally stable saponin B by the loss of its DDMP group. The influence of pH and the concentration of potassium hydroxide on transformation efficiency of the target compound was investigated. A solution of 0.25 M potassium hydroxide in 75% aqueous ethanol was suitable for converting the corresponding DDMP saponins of chickpeasaponin B1. The implementation by the combining MAE technique and alkaline hydrolysis method for preparing chickpeasaponin B1 provides a convenient technology for future applications.

  1. High-speed and high-efficiency travelling wave single-photon detectors embedded in nanophotonic circuits

    PubMed Central

    Pernice, W.H.P.; Schuck, C.; Minaeva, O.; Li, M.; Goltsman, G.N.; Sergienko, A.V.; Tang, H.X.

    2012-01-01

    Ultrafast, high-efficiency single-photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. However, imperfect modal matching and finite photon absorption rates have usually limited their maximum attainable detection efficiency. Here we demonstrate superconducting nanowire detectors atop nanophotonic waveguides, which enable a drastic increase of the absorption length for incoming photons. This allows us to achieve high on-chip single-photon detection efficiency up to 91% at telecom wavelengths, repeatable across several fabricated chips. We also observe remarkably low dark count rates without significant compromise of the on-chip detection efficiency. The detectors are fully embedded in scalable silicon photonic circuits and provide ultrashort timing jitter of 18 ps. Exploiting this high temporal resolution, we demonstrate ballistic photon transport in silicon ring resonators. Our direct implementation of a high-performance single-photon detector on chip overcomes a major barrier in integrated quantum photonics. PMID:23271658

  2. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

    The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

  3. Carbon use efficiency in optimal environments. [for photosynthesis in CELSS

    NASA Technical Reports Server (NTRS)

    Bugbee, Bruce

    1989-01-01

    The short- and long-term effects of environmental changes on plant productivity are studied using a model in which yield is determined by four factors: absorption of photosynthetic photon flux, photosynthetic efficiency, respiratory carbon use efficiency, and harvest index. The characteristics of the model are reviewed. Emphasis is given to the relationship between carbon use efficiency and yield. The biochemical pathways resulting in CO2 efflux are examined, including photorespiration, cyanide-resistant respiration, and dark respiration. The possibility of measuring photosynthesis and respiration in a CELSS is discussed.

  4. Two Photon Absorption in II-VI Semiconductors: The Influence of Dimensionality and Size.

    PubMed

    Scott, Riccardo; Achtstein, Alexander W; Prudnikau, Anatol; Antanovich, Artsiom; Christodoulou, Sotirios; Moreels, Iwan; Artemyev, Mikhail; Woggon, Ulrike

    2015-08-12

    We report a comprehensive study on the two-photon absorption cross sections of colloidal CdSe nanoplatelets, -rods, and -dots of different sizes by the means of z-scan and two-photon excitation spectroscopy. Platelets combine large particle volumes with ultra strong confinement. In contrast to weakly confined nanocrystals, the TPA cross sections of CdSe nanoplatelets scale superlinearly with volume (V(∼2)) and show ten times more efficient two-photon absorption than nanorods or dots. This unexpectedly strong shape dependence goes well beyond the effect of local fields. The larger the particles' aspect ratio, the greater is the confinement related electronic contribution to the increased two-photon absorption. Both electronic confinement and local field effects favor the platelets and make them unique two-photon absorbers with outstanding cross sections of up to 10(7) GM, the largest ever reported for (colloidal) semiconductor nanocrystals and ideally suited for two-photon imaging and nonlinear optoelectronics. The obtained results are confirmed by two independent techniques as well as a new self-referencing method.

  5. Molecular design of photovoltaic materials for polymer solar cells: toward suitable electronic energy levels and broad absorption.

    PubMed

    Li, Yongfang

    2012-05-15

    Bulk heterojunction (BHJ) polymer solar cells (PSCs) sandwich a blend layer of conjugated polymer donor and fullerene derivative acceptor between a transparent ITO positive electrode and a low work function metal negative electrode. In comparison with traditional inorganic semiconductor solar cells, PSCs offer a simpler device structure, easier fabrication, lower cost, and lighter weight, and these structures can be fabricated into flexible devices. But currently the power conversion efficiency (PCE) of the PSCs is not sufficient for future commercialization. The polymer donors and fullerene derivative acceptors are the key photovoltaic materials that will need to be optimized for high-performance PSCs. In this Account, I discuss the basic requirements and scientific issues in the molecular design of high efficiency photovoltaic molecules. I also summarize recent progress in electronic energy level engineering and absorption spectral broadening of the donor and acceptor photovoltaic materials by my research group and others. For high-efficiency conjugated polymer donors, key requirements are a narrower energy bandgap (E(g)) and broad absorption, relatively lower-lying HOMO (the highest occupied molecular orbital) level, and higher hole mobility. There are three strategies to meet these requirements: D-A copolymerization for narrower E(g) and lower-lying HOMO, substitution with electron-withdrawing groups for lower-lying HOMO, and two-dimensional conjugation for broad absorption and higher hole mobility. Moreover, better main chain planarity and less side chain steric hindrance could strengthen π-π stacking and increase hole mobility. Furthermore, the molecular weight of the polymers also influences their photovoltaic performance. To produce high efficiency photovoltaic polymers, researchers should attempt to increase molecular weight while maintaining solubility. High-efficiency D-A copolymers have been obtained by using benzodithiophene (BDT), dithienosilole

  6. Effect of dietary phosphorus on intestinal phosphorus absorption in growing Holstein steers.

    PubMed

    Feng, X; Ronk, E; Hanigan, M D; Knowlton, K F; Schramm, H; McCann, M

    2015-05-01

    The effect of dietary P intake on intestinal P absorption was evaluated in growing Holstein steers. Diets varying in P content (0.15, 0.27, 0.36, and 0.45%, DM basis) were fed to 8 steers (174±10kg of BW) fitted with permanent duodenal and ileal cannulas in a replicated 4×4 Latin square with 14-d periods. Ytterbium-labeled corn silage and cobalt-EDTA were used as particulate and liquid phase markers, respectively, to measure digesta flow. Duodenal and ileal samples and spot urine samples were collected every 9 h from d 11 to 14. Total fecal collection was conducted on d 11 to 14 with fecal bags. Blood samples were collected from the coccygeal vessel on d 14. Feed, digesta, and fecal samples were analyzed for total P and inorganic P. Data were analyzed using PROC GLIMMIX in SAS with a model including treatment, square, period, and interaction of treatment and square. Preplanned contrasts were used to evaluate linear and quadratic treatment effects. Results were reported as least squares means. Dry matter intake (mean=4.90kg/d, 2.8% of BW) and apparent DM digestibility (mean=78.1%) were unaffected by treatment. Duodenal and ileal flow of total P increased linearly with increasing P intake (13.4, 18.5, 23.0, and 27.4g/d; 6.80, 7.87, 8.42, and 10.4g/d). Increasing P intake increased the quantity of P absorbed from the small intestine linearly (6.96, 11.1, 14.6, and 17.2g/d), but absorption efficiency was unchanged (mean=59.6%). Phosphorus was absorbed on a net basis from the large intestine, but this was not affected by treatment and was a small proportion of total P absorption. Blood inorganic P increased linearly with increased dietary P (4.36, 6.31, 7.68, and 8.5mg/dL) and salivary P secretion was unchanged (mean=5.79g/d), suggesting that rumen function was prioritized during short-term P deficiency. These data showing an absence of change in absorption efficiency and salivary P secretion in the face of short-term P deficiency may be used to improve published

  7. Modification of pure oxygen absorption equipment for concurrent stripping of carbon dioxide

    USGS Publications Warehouse

    Watten, B.J.; Sibrell, P.L.; Montgomery, G.A.; Tsukuda, S.M.

    2004-01-01

    The high solubility of carbon dioxide precludes significant desorption within commercial oxygen absorption equipment. This operating characteristic of the equipment limits its application in recirculating water culture systems despite its ability to significantly increase allowable fish loading rates (kg/(L min)). Carbon dioxide (DC) is typically removed by air stripping. This process requires a significant energy input for forced air movement, air heating in cold climates and water pumping. We developed a modification for a spray tower that provides for carbon dioxide desorption as well as oxygen absorption. Elimination of the air-stripping step reduces pumping costs while allowing dissolved nitrogen to drop below saturation concentrations. This latter response provides for an improvement in oxygen absorption efficiency within the spray tower. DC desorption is achieved by directing head-space gases from the spray tower (O2, N2, CO2) through a sealed packed tower scrubber receiving a 2 N NaOH solution. Carbon dioxide is selectively removed from the gas stream, by chemical reaction, forming the product Na 2CO3. Scrubber off-gas, lean with regard to carbon dioxide but still rich with oxygen, is redirected through the spray tower for further stripping of DC and absorption of oxygen. Make-up NaOH is metered into the scrubbing solution sump on an as needed basis as directed by a feedback control loop programmed to maintain a scrubbing solution pH of 11.4-11.8. The spent NaOH solution is collected, then regenerated for reuse, in a batch process that requires relatively inexpensive hydrated lime (Ca(OH)2). A by-product of the regeneration step is an alkaline filter cake, which may have use in bio-solids stabilization. Given the enhanced gas transfer rates possible with chemical reaction, the required NaOH solution flow rate through the scrubber represents a fraction of the spray tower water flow rate. Further, isolation of the water being treated from the atmosphere (1

  8. Aqueous phase preparation of ultrasmall MoSe2 nanodots for efficient photothermal therapy of cancer cells

    NASA Astrophysics Data System (ADS)

    Yuwen, Lihui; Zhou, Jiajia; Zhang, Yuqian; Zhang, Qi; Shan, Jingyang; Luo, Zhimin; Weng, Lixing; Teng, Zhaogang; Wang, Lianhui

    2016-01-01

    Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation.Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation. Electronic supplementary information (ESI) available: Characterization, size distribution and EDS spectrum of MoSe2 NDs, calculation of

  9. Glutathionylation and Reduction of Methacrolein in Tomato Plants Account for Its Absorption from the Vapor Phase1[OPEN

    PubMed Central

    Muramoto, Shoko; Matsubara, Yayoi; Mwenda, Cynthia Mugo; Koeduka, Takao; Sakami, Takuya; Tani, Akira; Matsui, Kenji

    2015-01-01

    A large portion of the volatile organic compounds emitted by plants are oxygenated to yield reactive carbonyl species, which have a big impact on atmospheric chemistry. Deposition to vegetation driven by the absorption of reactive carbonyl species into plants plays a major role in cleansing the atmosphere, but the mechanisms supporting this absorption have been little examined. Here, we performed model experiments using methacrolein (MACR), one of the major reactive carbonyl species formed from isoprene, and tomato (Solanum lycopersicum) plants. Tomato shoots enclosed in a jar with MACR vapor efficiently absorbed MACR. The absorption efficiency was much higher than expected from the gas/liquid partition coefficient of MACR, indicating that MACR was likely metabolized in leaf tissues. Isobutyraldehyde, isobutyl alcohol, and methallyl alcohol (MAA) were detected in the headspace and inside tomato tissues treated with MACR vapor, suggesting that MACR was enzymatically reduced. Glutathione (GSH) conjugates of MACR (MACR-GSH) and MAA (MAA-GSH) were also detected. MACR-GSH was essentially formed through spontaneous conjugation between endogenous GSH and exogenous MACR, and reduction of MACR-GSH to MAA-GSH was likely catalyzed by an NADPH-dependent enzyme in tomato leaves. Glutathionylation was the metabolic pathway most responsible for the absorption of MACR, but when the amount of MACR exceeded the available GSH, MACR that accumulated reduced photosynthetic capacity. In an experiment simulating the natural environment using gas flow, MACR-GSH and MAA-GSH accumulation accounted for 30% to 40% of the MACR supplied. These results suggest that MACR metabolism, especially spontaneous glutathionylation, is an essential factor supporting MACR absorption from the atmosphere by tomato plants. PMID:26169680

  10. The quantum efficiency of HgCdTe photodiodes in relation to the direction of illumination and to their geometry

    NASA Technical Reports Server (NTRS)

    Rosenfeld, D.; Bahir, G.

    1993-01-01

    A theoretical study of the effect of the direction of the incident light on the quantum efficiency of homogeneous HgCdTe photodiodes suitable for sensing infrared radiation in the 8-12 microns atmospheric window is presented. The probability of an excess minority carrier to reach the junction is derived as a function of its distance from the edge of the depletion region. Accordingly, the quantum efficiency of photodiodes is presented for two geometries. In the first, the light is introduced directly to the area in which it is absorbed (opaque region), while in the second, the light passes through a transparent region before it reaches the opaque region. Finally, the performance of the two types of diodes is analyzed with the objective of finding the optimal width of the absorption area. The quantum efficiency depends strongly on the way in which the light is introduced. The structure in which the radiation is absorbed following its crossing the transparent region is associated with both higher quantum efficiency and homogeneity. In addition, for absorption region widths higher than a certain minimum, the quantum efficiency in this case is insensitive to the width of the absorption region.

  11. Pump polarization insensitive and efficient laser-diode pumped Yb:KYW ultrafast oscillator.

    PubMed

    Wang, Sha; Wang, Yan-Biao; Feng, Guo-Ying; Zhou, Shou-Huan

    2016-02-01

    We theoretically and experimentally report and evaluate a novel split laser-diode (LD) double-end pumped Yb:KYW ultrafast oscillator aimed at improving the performance of an ultrafast laser. Compared to a conventional unpolarized single-LD end-pumped ultrafast laser system, we improve the laser performance such as absorption efficiency, slope efficiency, cw mode-locking threshold, and output power by this new structure LD-pumped Yb:KYW ultrafast laser. Experiments were carried out with a 1 W output fiber-coupled LD. Experimental results show that the absorption increases from 38.7% to 48.4%, laser slope efficiency increases from 18.3% to 24.2%, cw mode-locking threshold decreases 12.7% from 630 to 550 mW in cw mode-locking threshold, and maximum output-power increases 28.5% from 158.4 to 221.5 mW when we switch the pump scheme from an unpolarized single-end pumping structure to a split LD double-end pumping structure.

  12. Optimization of Ionic Liquid-Assisted Extraction of Biflavonoids from Selaginella doederleinii and Evaluation of Its Antioxidant and Antitumor Activity.

    PubMed

    Li, Dan; Qian, Yan; Tian, Yu-Jia; Yuan, Shi-Meng; Wei, Wei; Wang, Gang

    2017-04-07

    As new green solvents, ionic liquids (ILs) have been generally applied in the extraction and separation of natural product. In this study, microwave assisted extraction based on IL (IL-MAE) was firstly employed to extract total biflavonoids from Selaginella doederleinii . Based on single-factor experiment, microwave power (300-700 W), extract time (30-50 min) and extract temperature (40-60 °C) on total bioflavonoids and antioxidant activities of the extracts were further investigated by a Box-Behnken design of response surface methodology (RSM) selecting total bioflavonoids yields and IC 50 of radical scavenging as index. Besides antioxidant activity of the extract was evaluated by a 2,2-diphenyl-1-picrylhydarzyl (DPPH) and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate (ABTS) radical scavenging assay, ferric reducing power assay and chelation of ferrous ions assay, and then anticaner activity was also researched against A549 cell line and 7721 cell line. The results illustrated that three factors and their interactions could be well suited for second-order polynomial models ( p < 0.05). Through process parameters, optimization of the extract (460 W, 40 min, and 45 °C) and detection of bioactivity, the yield of total bioflavonoids was 16.83 mg/g and IC 50 value was 56.24 μg/mL, respectively, indicating the extract has better anti-oxidation effect and antitumor activity. Furthermore, IL-MAE was the most efficient extracting method compared with MAE and Soxhlet extraction, which could improve extraction efficiency in a shorter time and at a lower temperature. In general, ILs-MAE was first adopted to establish a novel and green extraction process on the yields of total biflavonoids from S. doederleinii . In addition, the extract of containing biflavones showed potent antioxidant and anticancer capacity as a utilized valuable bioactive source for natural medicine.

  13. Efficient control of ultrafast optical nonlinearity of reduced graphene oxide by infrared reduction

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

    Bhattachraya, S.; Maiti, R.; Das, A. C.

    Simultaneous occurrence of saturable absorption nonlinearity and two-photon absorption nonlinearity in the same medium is well sought for the devices like optical limiter and laser mode-locker. Pristine graphene sheet consisting entirely of sp{sup 2}-hybridized carbon atoms has already been identified having large optical nonlinearity. However, graphene oxide (GO), a precursor of graphene having both sp{sup 2} and sp{sup 3}-hybridized carbon atom, is increasingly attracting cross-discipline researchers for its controllable properties by reduction of oxygen containing groups. In this work, GO has been prepared by modified Hummers method, and it has been further reduced by infrared (IR) radiation. Characterization of reducedmore » graphene oxide (RGO) by means of Raman spectroscopy, X-ray photoelectron spectroscopy, and UV-Visible absorption measurements confirms an efficient reduction with infrared radiation. Here, we report precise control of non-linear optical properties of RGO in femtosecond regime with increased degrees of IR reduction measured by open aperture z-scan technique. Depending on the intensity, both saturable absorption and two-photon absorption effects are found to contribute to the non-linearity of all the samples. Saturation dominates at low intensity (∼127 GW/cm{sup 2}) while two-photon absorption becomes prominent at higher intensities (from 217 GW/cm{sup 2} to 302 GW/cm{sup 2}). The values of two-photon absorption co-efficient (∼0.0022–0.0037 cm/GW for GO, and ∼0.0128–0.0143 cm/GW for RGO) and the saturation intensity (∼57 GW/cm{sup 2} for GO, and ∼194 GW/cm{sup 2} for RGO) increase with increasing reduction, indicating GO and RGO as novel tunable photonic devices. We have also explained the reason of tunable nonlinear optical properties by using amorphous carbon model.« less

  14. Unusual continuous dual absorption peaks in Ca-doped BiFeO3 nanostructures for broadened microwave absorption.

    PubMed

    Li, Zhong-Jun; Hou, Zhi-Ling; Song, Wei-Li; Liu, Xing-Da; Cao, Wen-Qiang; Shao, Xiao-Hong; Cao, Mao-Sheng

    2016-05-21

    Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3 nanoparticles via Ca doping, with the purpose of tailoring the phase boundary. Upon Ca-substitution, the co-existence of both R3c and P4mm phases has been confirmed to massively enhance both dielectric and magnetic properties via manipulating the phase boundary and the destruction of the spiral spin structure. Unlike the commonly reported magnetic/dielectric hybrid microwave absorption composites, Bi0.95Ca0.05FeO3 has been found to deliver unusual continuous dual absorption peaks at a small thickness (1.56 mm), which has remarkably broadened the effective absorption bandwidth (8.7-12.1 GHz). The fundamental mechanisms based on the phase boundary engineering have been discussed, suggesting a novel platform for designing advanced multiferroic materials with wide applications.

  15. Nondestructive evaluation of fatigue damage on low alloy steel by magnetomechanical acoustic emission technique

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

    Hiraasawa, T.; Saito, K.; Komura, I.

    1995-08-01

    A modified magnetomechanical acoustic emission (MAE) technique, denoted Pulse-MAE, in which the magnetization by current pulse was adopted, was newly developed and its applicability was assessed for the nondestructive detection and evaluation of fatigue damage in reactor pressure vessel steel SFVV2 and SA508 class2. MAE signals were measured with both conventional MAE and Pulse-MAE technique for fatigue damaged specimens having several damage fractions, and peak voltage ratio Vp/Vo, where Vp and Vo were the peak voltage for damaged and undamaged specimen respectively, was chosen as a measure. Vp/Vo was found to increase monotonously at the early stage of fatigue processmore » and the rate of increase in Vp/Vo during the fatigue process was larger in Pulse-MAE than conventional MAE. Therefore, Pulse-MAE technique proved to have higher sensitivity for the detection of fatigue damage compared with the conventional MAE and to have the potential of a practical technique for nondestructive detection and evaluation of fatigue damage in actual components.« less

  16. Excited state X-ray absorption spectroscopy: Probing both electronic and structural dynamics

    NASA Astrophysics Data System (ADS)

    Neville, Simon P.; Averbukh, Vitali; Ruberti, Marco; Yun, Renjie; Patchkovskii, Serguei; Chergui, Majed; Stolow, Albert; Schuurman, Michael S.

    2016-10-01

    We investigate the sensitivity of X-ray absorption spectra, simulated using a general method, to properties of molecular excited states. Recently, Averbukh and co-workers [M. Ruberti et al., J. Chem. Phys. 140, 184107 (2014)] introduced an efficient and accurate L 2 method for the calculation of excited state valence photoionization cross-sections based on the application of Stieltjes imaging to the Lanczos pseudo-spectrum of the algebraic diagrammatic construction (ADC) representation of the electronic Hamiltonian. In this paper, we report an extension of this method to the calculation of excited state core photoionization cross-sections. We demonstrate that, at the ADC(2)x level of theory, ground state X-ray absorption spectra may be accurately reproduced, validating the method. Significantly, the calculated X-ray absorption spectra of the excited states are found to be sensitive to both geometric distortions (structural dynamics) and the electronic character (electronic dynamics) of the initial state, suggesting that core excitation spectroscopies will be useful probes of excited state non-adiabatic dynamics. We anticipate that the method presented here can be combined with ab initio molecular dynamics calculations to simulate the time-resolved X-ray spectroscopy of excited state molecular wavepacket dynamics.

  17. Absorption and translocation of nitrogen in rhizomes of Leymus chinensis.

    PubMed

    Liu, Hongsheng; Liu, Huajie; Song, Youhong

    2011-03-15

    Leymus chinensis is a dominant species in the Inner Mongolia steppe, northern China. Plant growth in northern China grassland is often limited by low soil nitrogen availability. The objective of this study is to investigate whether rhizomes of Leymus chinensis are involved in the contribution of N uptake. The N concentration, (15)N concentration and (15)N proportion in roots, rhizomes and shoots after 48 h exposure of roots (L(root)) and rhizomes (L(rhizo)) separately and roots and rhizomes together (L(r+r)) to 0.1 mM (15)NH (4)(15)NO(3) solution were measured using root-splitting equipment and stable isotope ((15)N) techniques, respectively. The N content and dry mass were not affected by the labeling treatment. In contrast, the (15)N concentration in shoots, rhizomes and roots was significantly increased by the labeling in rhizomes, indicating that the inorganic nitrogen was absorbed via rhizomes from the solution and can be transported to other tissues, with preference to shoots rather than roots. Meanwhile, the absolute N absorption and translocation among compartments were also calculated. The N absorption via rhizomes was much smaller than via roots; however, the uptake efficiency per surface unit via rhizomes was greater than via roots. The capacity and high efficiency to absorb N nutrient via rhizomes enable plants to use transient nutrient supplies in the top soil surface. Copyright © 2011 John Wiley & Sons, Ltd.

  18. PHOTOSYNTHETIC EFFICIENCY OF MARINE PLANTS

    PubMed Central

    Yocum, C. S.; Blinks, L. R.

    1954-01-01

    Multicellular marine plants were collected from their natural habitats and the quantum efficiency of their photosynthesis was determined in the laboratory in five narrow wave length bands in the visible spectrum. The results along with estimates of the relative absorption by the various plastid pigments show a fairly uniform efficiency of 0.08 molecules O2 per absorbed quantum for (a) chlorophyll of one flowering plant, green algae, and brown algae, (b) fucoxanthol and other carotenoids of brown algae, and (c) the phycobilin pigments phycocyanin and phycoerythrin of red algae. The carotenoids of green algae are sometimes less efficient while those of red algae are largely or entirely inactive. Chlorophyll a of red algae is about one-half as efficient (φo2 = 0.04) as either the phycobilins, or the chlorophyll of most other plants. These results as well as those of high intensity and of fluorescence experiments are consistent with a mechanism in which about half the chlorophyll is inactive while the other half is fully active and is an intermediate in phycoerythrin- and phycocyanin-sensitized photosynthesis. PMID:13192311

  19. Antimicrobial and Antibiofilm Activities of Citrus Water-Extracts Obtained by Microwave-Assisted and Conventional Methods.

    PubMed

    Caputo, Leonardo; Quintieri, Laura; Cavalluzzi, Maria Maddalena; Lentini, Giovanni; Habtemariam, Solomon

    2018-06-17

    Citrus pomace is a huge agro-food industrial waste mostly composed of peels and traditionally used as compost or animal feed. Owing to its high content of compounds beneficial to humans (e.g., flavonoids, phenol-like acids, and terpenoids), citrus waste is increasingly used to produce valuable supplements, fragrance, or antimicrobials. However, such processes require sustainable and efficient extraction strategies by solvent-free techniques for environmentally-friendly good practices. In this work, we evaluated the antimicrobial and antibiofilm activity of water extracts of three citrus peels (orange, lemon, and citron) against ten different sanitary relevant bacteria. Both conventional extraction methods using hot water (HWE) and microwave-assisted extraction (MAE) were used. Even though no extract fully inhibited the growth of the target bacteria, these latter (mostly pseudomonads) showed a significant reduction in biofilm biomass. The most active extracts were obtained from orange and lemon peel by using MAE at 100 °C for 8 min. These results showed that citrus peel water infusions by MAE may reduce biofilm formation possibly enhancing the susceptibility of sanitary-related bacteria to disinfection procedures.

  20. Optimization of microwave-assisted extraction of total extract, stevioside and rebaudioside-A from Stevia rebaudiana (Bertoni) leaves, using response surface methodology (RSM) and artificial neural network (ANN) modelling.

    PubMed

    Ameer, Kashif; Bae, Seong-Woo; Jo, Yunhee; Lee, Hyun-Gyu; Ameer, Asif; Kwon, Joong-Ho

    2017-08-15

    Stevia rebaudiana (Bertoni) consists of stevioside and rebaudioside-A (Reb-A). We compared response surface methodology (RSM) and artificial neural network (ANN) modelling for their estimation and predictive capabilities in building effective models with maximum responses. A 5-level 3-factor central composite design was used to optimize microwave-assisted extraction (MAE) to obtain maximum yield of target responses as a function of extraction time (X 1 : 1-5min), ethanol concentration, (X 2 : 0-100%) and microwave power (X 3 : 40-200W). Maximum values of the three output parameters: 7.67% total extract yield, 19.58mg/g stevioside yield, and 15.3mg/g Reb-A yield, were obtained under optimum extraction conditions of 4min X 1 , 75% X 2 , and 160W X 3 . The ANN model demonstrated higher efficiency than did the RSM model. Hence, RSM can demonstrate interaction effects of inherent MAE parameters on target responses, whereas ANN can reliably model the MAE process with better predictive and estimation capabilities. Copyright © 2017. Published by Elsevier Ltd.

  1. Laser engines operating by resonance absorption. [thermodynamic feasibility study

    NASA Technical Reports Server (NTRS)

    Garbuny, M.; Pechersky, M. J.

    1976-01-01

    Basic tutorial article on the thermodynamic feasibility of laser engines at the present state of the art. Three main options are considered: (1) laser power applied externally to a heat reservoir (boiler approach); (2) internal heating of working fluid by resonance absorption; and (3) direct conversion of selective excitation into work. Only (2) is considered practically feasible at present. Basic concepts and variants, efficiency relations, upper temperature limits of laser engines, selection of absorbing gases, engine walls, bleaching, thermodynamic cycles of optimized laser engines, laser-powered turbines, laser heat pumps are discussed. Photon engines and laser dissociation engines are also considered.

  2. Highly efficient SO2 capture by dual functionalized ionic liquids through a combination of chemical and physical absorption.

    PubMed

    Cui, Guokai; Wang, Congmin; Zheng, Junjie; Guo, Yan; Luo, Xiaoyan; Li, Haoran

    2012-03-07

    Two kinds of dual functionalized ionic liquids with ether-functionalized cations and tetrazolate anions were designed, prepared, and used for SO(2) capture, which exhibit an extremely high SO(2) capacity and excellent reversibility through a combination of chemical and physical absorption. This journal is © The Royal Society of Chemistry 2012

  3. Highly efficient ultrathin-film amorphous silicon solar cells on top of imprinted periodic nanodot arrays

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

    Yan, Wensheng, E-mail: yws118@gmail.com; Gu, Min, E-mail: mgu@swin.edu.au; Tao, Zhikuo

    2015-03-02

    The addressing of the light absorption and conversion efficiency is critical to the ultrathin-film hydrogenated amorphous silicon (a-Si:H) solar cells. We systematically investigate ultrathin a-Si:H solar cells with a 100 nm absorber on top of imprinted hexagonal nanodot arrays. Experimental evidences are demonstrated for not only notable silver nanodot arrays but also lower-cost ITO and Al:ZnO nanodot arrays. The measured external quantum efficiency is explained by the simulation results. The J{sub sc} values are 12.1, 13.0, and 14.3 mA/cm{sup 2} and efficiencies are 6.6%, 7.5%, and 8.3% for ITO, Al:ZnO, and silver nanodot arrays, respectively. Simulated optical absorption distribution shows high lightmore » trapping within amorphous silicon layer.« less

  4. Paleoseismology of Sinistral-Slip Fault System, Focusing on the Mae Chan Fault, on the Shan Plateau, SE Asia.

    NASA Astrophysics Data System (ADS)

    Curtiss, E. R.; Weldon, R. J.; Wiwegwin, W.; Weldon, E. M.

    2017-12-01

    The Shan Plateau, which includes portions of Myanmar, China, Thailand, Laos, and Vietnam lies between the dextral NS-trending Sagaing and SE-trending Red River faults and contains 14 active E-W sinistral-slip faults, including the Mae Chan Fault (MCF) in northern Thailand. The last ground-rupturing earthquake to occur on the broader sinistral fault system was the M6.8 Tarlay earthquake in Myanmar in March 2011 on the Nam Ma fault immediately north of the MCF the last earthquake to occur on the MCF was a M4.0 in the 5th century that destroyed the entire city of Wiang Yonok (Morley et al., 2011). We report on a trenching study of the MCF, which is part of a broader study to create a regional seismic hazard map of the entire Shan Plateau. By studying the MCF, which appears to be representative of the sinistral faults, and easy to work on, we hope to characterize both it and the other unstudied faults in the system. As part of a paleoseismology training course we dug two trenches at the Pa Tueng site on the MCF, within an offset river channel and the trenches exposed young sediment with abundant charcoal (in process of dating), cultural artifacts, and evidence for the last two (or three) ground-rupturing earthquakes on the fault. We hope to use the data from this site to narrow the recurrence interval, which is currently to be 2,000-4,000 years and the slip rate of 1-2 mm/year, being developed at other sites on the fault. By extrapolating the data of the MCF to the other faults we will have a better understanding of the whole fault system. Once we have characterized the MCF, we plan to use geomorphic offsets and strain rates from regional GPS to relatively estimate the activity of the other faults in this sinistral system.

  5. On the sub-band gap optical absorption in heat treated cadmium sulphide thin film deposited on glass by chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, P.; Karim, B.; Guha Roy, S.

    2013-12-01

    The sub-band gap optical absorption in chemical bath deposited cadmium sulphide thin films annealed at different temperatures has been critically analyzed with special reference to Urbach relation. It has been found that the absorption co-efficient of the material in the sub-band gap region is nearly constant up to a certain critical value of the photon energy. However, as the photon energy exceeds the critical value, the absorption coefficient increases exponentially indicating the dominance of Urbach rule. The absorption coefficients in the constant absorption region and the Urbach region have been found to be sensitive to annealing temperature. A critical examination of the temperature dependence of the absorption coefficient indicates two different kinds of optical transitions to be operative in the sub-band gap region. After a careful analyses of SEM images, energy dispersive x-ray spectra, and the dc current-voltage characteristics, we conclude that the absorption spectra in the sub-band gap domain is possibly associated with optical transition processes involving deep levels and the grain boundary states of the material.

  6. Spectral Absorption Properties of Atmospheric Aerosols

    NASA Technical Reports Server (NTRS)

    Bergstrom, R. W.; Pilewskie, P.; Russell, P. B.; Redemann, J.; Bond, T. C.; Quinn, P. K.; Sierau, B.

    2007-01-01

    We have determined the solar spectral absorption optical depth of atmospheric aerosols for specific case studies during several field programs (three cases have been reported previously; two are new results). We combined airborne measurements of the solar net radiant flux density and the aerosol optical depth with a detailed radiative transfer model for all but one of the cases. The field programs (SAFARI 2000, ACE Asia, PRIDE, TARFOX, INTEX-A) contained aerosols representing the major absorbing aerosol types: pollution, biomass burning, desert dust and mixtures. In all cases the spectral absorption optical depth decreases with wavelength and can be approximated with a power-law wavelength dependence (Absorption Angstrom Exponent or AAE). We compare our results with other recent spectral absorption measurements and attempt to briefly summarize the state of knowledge of aerosol absorption spectra in the atmosphere. We discuss the limitations in using the AAE for calculating the solar absorption. We also discuss the resulting spectral single scattering albedo for these cases.

  7. Efficient semitransparent perovskite solar cells for 23.0%-efficiency perovskite/silicon four-terminal tandem cells

    DOE PAGES

    Chen, Bo; Bai, Yang; Yu, Zhengshan; ...

    2016-07-19

    Here, we have investigated semi-transparent perovskite solar cells and infrared enhanced silicon heterojunction cells for high-efficiency tandem devices. A semi-transparent metal electrode with good electrical conductivity and optical transparency has been fabricated by thermal evaporation of 7 nm of Au onto a 1-nm-thick Cu seed layer. For this electrode to reach its full potential, MAPbI3 thin films were formed by a modified one-step spin-coating method, resulting in a smooth layer that allowed the subsequent metal thin film to remain continuous. The fabricated semi-transparent perovskite solar cells demonstrated 16.5% efficiency under one-sun illumination, and were coupled with infrared-enhanced silicon heterojunction cellsmore » tuned specifically for perovskite/Si tandem devices. A double-layer antireflection coating at the front side and MgF2 reflector at rear side of the silicon heterojunction cells reduced parasitic absorption of near-infrared light, leading to 6.5% efficiency after filtering with a perovskite device and 23.0% summed efficiency for the perovskite/Si tandem device.« less

  8. Efficient semitransparent perovskite solar cells for 23.0%-efficiency perovskite/silicon four-terminal tandem cells

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

    Chen, Bo; Bai, Yang; Yu, Zhengshan

    Here, we have investigated semi-transparent perovskite solar cells and infrared enhanced silicon heterojunction cells for high-efficiency tandem devices. A semi-transparent metal electrode with good electrical conductivity and optical transparency has been fabricated by thermal evaporation of 7 nm of Au onto a 1-nm-thick Cu seed layer. For this electrode to reach its full potential, MAPbI3 thin films were formed by a modified one-step spin-coating method, resulting in a smooth layer that allowed the subsequent metal thin film to remain continuous. The fabricated semi-transparent perovskite solar cells demonstrated 16.5% efficiency under one-sun illumination, and were coupled with infrared-enhanced silicon heterojunction cellsmore » tuned specifically for perovskite/Si tandem devices. A double-layer antireflection coating at the front side and MgF2 reflector at rear side of the silicon heterojunction cells reduced parasitic absorption of near-infrared light, leading to 6.5% efficiency after filtering with a perovskite device and 23.0% summed efficiency for the perovskite/Si tandem device.« less

  9. Corrosion Problems in Absorption Chillers

    ERIC Educational Resources Information Center

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  10. [Shock absorption of mouthguard materials--influence of temperature conditions and shore hardness on shock absorption].

    PubMed

    Tomita, Takashi; Tsukimura, Naoki; Ohno, Shigeru; Umekawa, Yoshitada; Sawano, Muneyuki; Fujimoto, Toshiki; Takamura, Masaaki; Majima, Aiko; Katakura, Yuusuke; Kurata, Akemi; Ohyama, Tetsuo; Ishigami, Tomohiko

    2006-04-01

    To consider changes in the physical properties of mouthguard materials with the change of temperature, shock-absorbing examination and Shore hardness measurement of existing MG materials and other elastic materials were carried out. Both examinations were done under two temperature conditions: at room temperature (25 degrees C) and simulated intraoral temperature (37 degrees C). In addition, a comparative study of the relation between Shore hardness and shock absorption of the materials was made. A self-made drop impact machine was used for the shock-absorbing examination. The thickness of a sample was assumed to be 3 mm. The loading was applied by dropping 3 kinds of steel ball, phi 10 mm (4.0 g), phi 15 mm (13.7 g), and phi 20 mm (32.6 g) from a height of 60 cm. The shock absorption of all materials was compared by the maximum impact force. Shore hardness was measured based on the JIS standard. The shock absorption of each material showed a different tendency depending on the loading condition. Furthermore, the shock absorption of the same material showed different results depending on the temperature condition. Shore hardness measurements tended to show low values with the condition of 37 degrees C for all materials. From the relation between shock absorption and Shore hardness, it was confirmed that there is a correlation between hardness and the maximum impact force in the materials that showed shock absorption by elastic deformation. Some materials showed high shock absorption compared with existing MG materials.

  11. Mathematical model of zinc absorption: effects of dietary calcium, protein and iron on zinc absorption

    PubMed Central

    Miller, Leland V.; Krebs, Nancy F.; Hambidge, K. Michael

    2013-01-01

    A previously described mathematical model of Zn absorption as a function of total daily dietary Zn and phytate was fitted to data from studies in which dietary Ca, Fe and protein were also measured. An analysis of regression residuals indicated statistically significant positive relationships between the residuals and Ca, Fe and protein, suggesting that the presence of any of these dietary components enhances Zn absorption. Based on the hypotheses that (1) Ca and Fe both promote Zn absorption by binding with phytate and thereby making it unavailable for binding Zn and (2) protein enhances the availability of Zn for transporter binding, the model was modified to incorporate these effects. The new model of Zn absorption as a function of dietary Zn, phytate, Ca, Fe and protein was then fitted to the data. The proportion of variation in absorbed Zn explained by the new model was 0·88, an increase from 0·82 with the original model. A reduced version of the model without Fe produced an equally good fit to the data and an improved value for the model selection criterion, demonstrating that when dietary Ca and protein are controlled for, there is no evidence that dietary Fe influences Zn absorption. Regression residuals and testing with additional data supported the validity of the new model. It was concluded that dietary Ca and protein modestly enhanced Zn absorption and Fe had no statistically discernable effect. Furthermore, the model provides a meaningful foundation for efforts to model nutrient interactions in mineral absorption. PMID:22617116

  12. Mathematical model of zinc absorption: effects of dietary calcium, protein and iron on zinc absorption.

    PubMed

    Miller, Leland V; Krebs, Nancy F; Hambidge, K Michael

    2013-02-28

    A previously described mathematical model of Zn absorption as a function of total daily dietary Zn and phytate was fitted to data from studies in which dietary Ca, Fe and protein were also measured. An analysis of regression residuals indicated statistically significant positive relationships between the residuals and Ca, Fe and protein, suggesting that the presence of any of these dietary components enhances Zn absorption. Based on the hypotheses that (1) Ca and Fe both promote Zn absorption by binding with phytate and thereby making it unavailable for binding Zn and (2) protein enhances the availability of Zn for transporter binding, the model was modified to incorporate these effects. The new model of Zn absorption as a function of dietary Zn, phytate, Ca, Fe and protein was then fitted to the data. The proportion of variation in absorbed Zn explained by the new model was 0·88, an increase from 0·82 with the original model. A reduced version of the model without Fe produced an equally good fit to the data and an improved value for the model selection criterion, demonstrating that when dietary Ca and protein are controlled for, there is no evidence that dietary Fe influences Zn absorption. Regression residuals and testing with additional data supported the validity of the new model. It was concluded that dietary Ca and protein modestly enhanced Zn absorption and Fe had no statistically discernable effect. Furthermore, the model provides a meaningful foundation for efforts to model nutrient interactions in mineral absorption.

  13. New Triplet Sensitization Routes for Photon Upconversion: Thermally Activated Delayed Fluorescence Molecules, Inorganic Nanocrystals, and Singlet-to-Triplet Absorption.

    PubMed

    Yanai, Nobuhiro; Kimizuka, Nobuo

    2017-10-17

    Photon upconversion based on triplet-triplet annihilation (TTA-UC) has attracted much interest because of its possible applications to renewable energy production and biological fields. In particular, the UC of near-infrared (NIR) light to visible (vis) light is imperative to overcome the Shockley-Queisser limit of single-junction photovoltaic cells, and the efficiency of photocatalytic hydrogen production from water can also be improved with the aid of vis-to-ultraviolet (UV) UC. However, both processes have met limitations in the wavelength range, efficiency, and sensitivity for weak incident light. This Account describes recent breakthroughs that solve these major problems, new triplet sensitization routes to significantly enlarge the range of conversion wavelength by minimizing the energy loss during intersystem crossing (ISC) of triplet sensitizers or bypassing the ISC process. The photochemical processes of TTA-UC in general start with the absorption of longer wavelength incident light by triplet sensitizers, which generate the triplet states via ISC. This ISC inevitably accompanies the energy loss of hundreds of millielectronvolts, which significantly limits the TTA-UC with large anti-Stokes shifts. The small S 1 -T 1 gap of molecules showing thermally activated delayed fluorescence (TADF) allows the sensitization of emitters with the highest T 1 and S 1 energy levels ever employed in TTA-UC, which results in efficient vis-to-UV UC. As alternatives to molecular sensitizers in the NIR region, inorganic nanocrystals with broad NIR absorption bands have recently been shown to work as effective sensitizers for NIR-to-vis TTA-UC. Their small exchange splitting minimizes the energy loss during triplet sensitization. The modification of nanocrystal surfaces with organic acceptors via coordination bonds allows efficient energy transfer between the components and succeeding TTA processes. To remove restrictions on the energy loss during ISC, molecules with direct

  14. Numerical simulation and experimental validation of the large deformation bending and folding behavior of magneto-active elastomer composites

    NASA Astrophysics Data System (ADS)

    Sheridan, Robert; Roche, Juan; Lofland, Samuel E.; vonLockette, Paris R.

    2014-09-01

    This work seeks to provide a framework for the numerical simulation of magneto-active elastomer (MAE) composite structures for use in origami engineering applications. The emerging field of origami engineering employs folding techniques, an array of crease patterns traditionally on a single flat sheet of paper, to produce structures and devices that perform useful engineering operations. Effective means of numerical simulation offer an efficient way to optimize the crease patterns while coupling to the performance and behavior of the active material. The MAE materials used herein are comprised of nominally 30% v/v, 325 mesh barium hexafarrite particles embedded in Dow HS II silicone elastomer compound. These particulate composites are cured in a magnetic field to produce magneto-elastic solids with anisotropic magnetization, e.g. they have a preferred magnetic axis parallel to the curing axis. The deformed shape and/or blocked force characteristics of these MAEs are examined in three geometries: a monolithic cantilever as well as two- and four-segment composite accordion structures. In the accordion structures, patches of MAE material are bonded to a Gelest OE41 unfilled silicone elastomer substrate. Two methods of simulation, one using the Maxwell stress tensor applied as a traction boundary condition and another employing a minimum energy kinematic (MEK) model, are investigated. Both methods capture actuation due to magnetic torque mechanisms that dominate MAE behavior. Comparison with experimental data show good agreement with only a single adjustable parameter, either an effective constant magnetization of the MAE material in the finite element models (at small and moderate deformations) or an effective modulus in the minimum energy model. The four-segment finite element model was prone to numerical locking at large deformation. The effective magnetization and modulus values required are a fraction of the actual experimentally measured values which suggests a

  15. Absorption of polycyclic aromatic hydrocarbons by a highly absorptive polymeric medium.

    PubMed

    Francisco, Olga; Idowu, Ifeoluwa; Friesen, Kelsey L; McDougall, Matthew; Choi, Sara Seoin; Bolluch, Patrique; Daramola, Oluwadamilola; Johnson, Wesley; Palace, Vince; Stetefeld, Jörg; Tomy, Gregg T

    2018-06-01

    The efficacy of a lightly cross-linked polymeric bead to absorb polycyclic aromatic hydrocarbons (PAHs) from the surface of fresh- and salt-water in a simulated oil-spill scenario was assessed in this study. A layer of PAHs at the water surface was created by first preparing the PAHs in hexane and then carefully spiking this mixture onto the surface of water. Beads were then applied to the surface of the organic phase and the amount of hydrocarbons absorbed by the beads was examined at prescribed time intervals and at different temperatures. Absorption of PAHs into the beads was exhaustive with ∼86 ± 4% being selectively removed from the organic phase by 120 s. First order reaction rates best described the uptake kinetics and absorption rates ranged from 0.0085 (naphthalene) to 0.0325 s- 1 (dibenzo[a,h]anthracene). Absorption of PAHs into the beads was driven by molecular volume (A 3 ). Uptake rates increased markedly for PAHs with molecular volumes between 130 A 3 and 190 A 3 . Beyond this molecular volume there was no apparent change in the rate of uptake. This study shows that these polymeric beads have a high affinity for PAHs and can be used under various environmental conditions with negligible difference in absorptive efficacy. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Spectral Absorption By Particulate Impurities in Snow Determined By Photometric Analysis Of Filters

    NASA Astrophysics Data System (ADS)

    Grenfell, T. C.; Doherty, S. J.; Clarke, A. D.

    2009-12-01

    Our work is motivated by the 1983-84 survey by Clarke and Noone (Atmos. Environ., 1985) of soot in Arctic snow. Our objective is to resurvey the original area they covered and to extend the observations around the entire Arctic Basin under the auspices of the IPY program. We use the filtering and integrating sandwich techniques developed by Clarke and Noone to process the snow samples. Among the advantages of this method are that (a) it provides a direct measure of light absorption and the result is closely related to the actual absorption of sunlight in the snow or ice, (b) processing and filtering of the snow samples can be carried out in remote locations and (c) it is not necessary to transport large quantities of snow back to our home laboratory. Here we describe the construction, calibration, and some applications of an integrating sphere spectrophotometer system designed to take advantage of recent advances in instrumentation to improve the accuracy of measurements of absorption by particulate impurities collected on nuclepore filters used in our survey. Filter loading in terms of effective black carbon (BC) amount is determined together with the ratio of non-BC to BC concentrations using a set of reference filters with known loadings of Monarch 71 BC prepared by A. D. Clarke. The new spectrophotometer system has (a) system stability of approximately 0.5%; (b) precision relative to ADC standards of 3-4% for filter loadings greater than about 0.5 microgm Carbon/cm2. (c) We can distinguish BC from non-BC from relative spectral shapes of the energy absorption curves with an accuracy that depends on our knowledge of the spectral absorption curves of the non-BC components; and (d) by-eye estimates are consistent with spectrophotometric results. The major outstanding uncertainty is the appropriate value to use for the mass absorption efficiency for BC.

  17. Efficient Carrier Multiplication in Colloidal Silicon Nanorods

    DOE PAGES

    Stolle, Carl Jackson; Lu, Xiaotang; Yu, Yixuan; ...

    2017-08-01

    In this study, auger recombination lifetimes, absorption cross sections, and the quantum yields of carrier multiplication (CM), or multiexciton generation (MEG), were determined for solvent-dispersed silicon (Si) nanorods using transient absorption spectroscopy (TAS). Nanorods with an average diameter of 7.5 nm and aspect ratios of 6.1, 19.3, and 33.2 were examined. Colloidal Si nanocrystals of similar diameters were also studied for comparison. The nanocrystals and nanorods were passivated with organic ligands by hydrosilylation to prevent surface oxidation and limit the effects of surface trapping of photoexcited carriers. All samples used in the study exhibited relatively efficient photoluminescence. The Auger lifetimesmore » increased with nanorod length, and the nanorods exhibited higher CM quantum yield and efficiency than the nanocrystals with a similar band gap energy E g. Beyond a critical length, the CM quantum yield decreases. Finally, nanorods with the aspect ratio of 19.3 had the highest CM quantum yield of 1.6 ± 0.2 at 2.9E g, which corresponded to a multiexciton yield that was twice as high as observed for the spherical nanocrystals.« less

  18. Perfect absorption of low-frequency sound waves by critically coupled subwavelength resonant system

    NASA Astrophysics Data System (ADS)

    Long, Houyou; Cheng, Ying; Tao, Jiancheng; Liu, Xiaojun

    2017-01-01

    The perfect absorption (PA) for low-frequency audible sound waves has been achieved by critically coupling the inherent loss factor to the inherent leakage factor of a system, which is constructed by attaching a deep-subwavelength lossy resonant plate (LRP) to a backed rigid wall closely. We have certified it by using the graphical method in the complex frequency plane. By coupling the LRP to an air cavity in front of the rigid wall, the high efficient (>80%) low-frequency broadband absorption is obtained from 99.1 Hz to 294.8 Hz. Here, the thickness of LRP is only 1/13.5 of the relevant wavelength at 294.8 Hz. The impedance analyses further demonstrate that the impedances are perfectly matched between the system and the surrounding background medium at PA.

  19. Enhanced light absorption in waveguide Schottky photodetector integrated with ultrathin metal/silicide stripe.

    PubMed

    Guo, Jingshu; Wu, Zhiwei; Zhao, Yanli

    2017-05-01

    We investigate the light absorption enhancement in waveguide Schottky photodetector integrated with ultrathin metal/silicide stripe, which can provide high internal quantum efficiency. By using aab0-quasi-TE hybrid modes for the first time, a high absorptance of 95.6% is achieved in 5 nm thick Au stripe with area of only 0.14 μm2, without using resonance structure. In theory, the responsivity, dark current, and 3dB bandwidth of the corresponding device are 0.146 A/W, 8.03 nA, and 88 GHz, respectively. For most silicides, the quasi-TM mode should be used in this device, and an optimized PtSi device has a responsivity of 0.71 A/W and a dark current of 35.9 μA.

  20. Optical absorption and emission bands of Tm 3+ ions in calcium niobium gallium garnet crystal

    NASA Astrophysics Data System (ADS)

    Tsuboi, Taiju; Tanigawa, Masayuki; Shimamura, Kiyoshi

    2000-12-01

    Absorption spectra of Tm 3+ ions in Ca 3Nb 1.6875Ga 3.1875O 12 (CNGG) crystal have been investigated at various temperatures between 15 and 296 K. Luminescence spectra in a spectral region of 400-1750 nm are investigated under excitation into various excited states of Tm 3+ and the conduction band of CNGG at room temperature. The absorption and emission bands of Tm 3+ in CNGG are observed to be broader than those observed in other Tm 3+-doped crystals such as LiNbO 3. This is due to the disordered structure of CNGG. From the temperature dependence of absorption spectra, five Stark levels are derived for the 3H 6 ground state. The highest Stark level is found to be 351 cm -1 above the ground level. It is suggested that the low efficiency of the 2.02 μm lasing at room temperature is due to the narrow splitting of the Stark levels.

  1. Brown and black carbon in Beijing aerosol: Implications for the effects of brown coating on light absorption by black carbon.

    PubMed

    Cheng, Yuan; He, Ke-Bin; Engling, Guenter; Weber, Rodney; Liu, Jiu-Meng; Du, Zhen-Yu; Dong, Shu-Ping

    2017-12-01

    Brown carbon (BrC) is increasingly included in climate models as an emerging category of particulate organic compounds that can absorb solar radiation efficiently at specific wavelengths. Water-soluble organic carbon (WSOC) has been commonly used as a surrogate for BrC; however, it only represents a limited fraction of total organic carbon (OC) mass, which could be as low as about 20% in urban atmosphere. Using methanol as the extraction solvent, up to approximately 90% of the OC in Beijing aerosol was isolated and measured for absorption spectra over the ultraviolet-to-visible wavelength range. Compared to methanol-soluble OC (MSOC), WSOC underestimated BrC absorption by about 50% at 365nm. The mass absorption efficiencies measured for BrC in Beijing aerosol were converted to the imaginary refractive indices of BrC and subsequently used to compute BrC coating-induced enhancement of light absorption (E abs ) by black carbon. E abs attributed to lensing was reduced in the case of BrC coating relative to that caused by purely-scattering coating. However, this reduction was overwhelmed by the effect of BrC shell absorption, indicating that the overall effect of BrC coating was an increase in E abs . Methanol extraction significantly reduced charring of OC during thermal-optical analysis, leading to a large increase in the measured elemental carbon (EC) mass and an apparent improvement in the consistency of EC measurements by different thermal-optical methods. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Efficient upconversion-pumped continuous wave Er3+:LiLuF4 lasers

    NASA Astrophysics Data System (ADS)

    Moglia, Francesca; Müller, Sebastian; Reichert, Fabian; Metz, Philip W.; Calmano, Thomas; Kränkel, Christian; Heumann, Ernst; Huber, Günter

    2015-04-01

    We report on detailed spectroscopic investigations and efficient visible upconversion laser operation of Er3+:LiLuF4. This material allows for efficient resonant excited-state-absorption (ESA) pumping at 974 nm. Under spectroscopic conditions without external feedback, ESA at the laser wavelength of 552 nm prevails stimulated emission. Under lasing conditions in a resonant cavity, the high intracavity photon density bleaches the ESA at 552 nm, allowing for efficient cw laser operation. We obtained the highest output power of any room-temperature crystalline upconversion laser. The laser achieves a cw output power of 774 mW at a slope efficiency of 19% with respect to the incident pump power delivered by an optically-pumped semiconductor laser. The absorption efficiency of the pump radiation is estimated to be below 50%. To exploit the high confinement in waveguides for this laser, we employed femtosecond-laser pulses to inscribe a cladding of parallel tracks of modified material into Er3+:LiLuF4 crystals. The core material allows for low-loss waveguiding at pump and laser wavelengths. Under Ti:sapphire pumping at 974 nm, the first crystalline upconversion waveguide laser has been realized. We obtained waveguide-laser operation with up to 10 mW of output power at 553 nm.

  3. An Accurate Absorption-Based Net Primary Production Model for the Global Ocean

    NASA Astrophysics Data System (ADS)

    Silsbe, G.; Westberry, T. K.; Behrenfeld, M. J.; Halsey, K.; Milligan, A.

    2016-02-01

    As a vital living link in the global carbon cycle, understanding how net primary production (NPP) varies through space, time, and across climatic oscillations (e.g. ENSO) is a key objective in oceanographic research. The continual improvement of ocean observing satellites and data analytics now present greater opportunities for advanced understanding and characterization of the factors regulating NPP. In particular, the emergence of spectral inversion algorithms now permits accurate retrievals of the phytoplankton absorption coefficient (aΦ) from space. As NPP is the efficiency in which absorbed energy is converted into carbon biomass, aΦ measurements circumvents chlorophyll-based empirical approaches by permitting direct and accurate measurements of phytoplankton energy absorption. It has long been recognized, and perhaps underappreciated, that NPP and phytoplankton growth rates display muted variability when normalized to aΦ rather than chlorophyll. Here we present a novel absorption-based NPP model that parameterizes the underlying physiological mechanisms behind this muted variability, and apply this physiological model to the global ocean. Through a comparison against field data from the Hawaii and Bermuda Ocean Time Series, we demonstrate how this approach yields more accurate NPP measurements than other published NPP models. By normalizing NPP to satellite estimates of phytoplankton carbon biomass, this presentation also explores the seasonality of phytoplankton growth rates across several oceanic regions. Finally, we discuss how future advances in remote-sensing (e.g. hyperspectral satellites, LIDAR, autonomous profilers) can be exploited to further improve absorption-based NPP models.

  4. Investigating the variability in brown carbon light-absorption properties

    NASA Astrophysics Data System (ADS)

    Saleh, R.; Cheng, Z.; Atwi, K.

    2017-12-01

    Combustion of biomass fuels contributes a significant portion of brown carbon (BrC), the light-absorbing fraction of organic aerosols. BrC exhibits highly variable light-absorption properties, with imaginary part of the refractive indices (k) reported in the literature varying over two orders of magnitude. This high variability in k is attributed to the chaotic nature of combustion; however, there is a major gap in the fundamental understanding of this variability. To address this gap, we hypothesize that BrC is comprised of black carbon (BC) precursors whose transformation to BC has not seen fruition. Depending on the combustion conditions, these BC precursors exhibit different maturity levels which dictate their light-absorption properties (k). The more mature are the precursors, the more absorptive (or BC-like) they are. Therefore, k of BrC obtained from a certain measurement depends on the specific combustion conditions associated with the measurement, leading to the aforementioned variability in the literature. To test this hypothesis, we performed controlled combustion experiments in which the combustion conditions (temperature and air/fuel ratio) were varied and k was retrieved from real-time multi-wavelength light-absorption measurements at each condition. We used benzene, the inception of which during combustion is the initial critical step leading to BC formation, as a model fuel. By varying the combustion conditions from relatively inefficient (low temperature and/or air/fuel ratio) to relatively efficient (high temperature and/or air/fuel ratio), we isolated BrC components with progressively increasing k, spanning the wide range reported in the literature. We also performed thermodenuder measurements to constrain the volatility of the BrC, as well as laser desorption ionization mass spectrometry analysis to constrain its molecular mass. We found that as the combustion conditions approached the BC-formation threshold, the increase in k was associated

  5. Observational insights into aerosol formation from isoprene.

    PubMed

    Worton, David R; Surratt, Jason D; Lafranchi, Brian W; Chan, Arthur W H; Zhao, Yunliang; Weber, Robin J; Park, Jeong-Hoo; Gilman, Jessica B; de Gouw, Joost; Park, Changhyoun; Schade, Gunnar; Beaver, Melinda; Clair, Jason M St; Crounse, John; Wennberg, Paul; Wolfe, Glenn M; Harrold, Sara; Thornton, Joel A; Farmer, Delphine K; Docherty, Kenneth S; Cubison, Michael J; Jimenez, Jose-Luis; Frossard, Amanda A; Russell, Lynn M; Kristensen, Kasper; Glasius, Marianne; Mao, Jingqiu; Ren, Xinrong; Brune, William; Browne, Eleanor C; Pusede, Sally E; Cohen, Ronald C; Seinfeld, John H; Goldstein, Allen H

    2013-10-15

    Atmospheric photooxidation of isoprene is an important source of secondary organic aerosol (SOA) and there is increasing evidence that anthropogenic oxidant emissions can enhance this SOA formation. In this work, we use ambient observations of organosulfates formed from isoprene epoxydiols (IEPOX) and methacrylic acid epoxide (MAE) and a broad suite of chemical measurements to investigate the relative importance of nitrogen oxide (NO/NO2) and hydroperoxyl (HO2) SOA formation pathways from isoprene at a forested site in California. In contrast to IEPOX, the calculated production rate of MAE was observed to be independent of temperature. This is the result of the very fast thermolysis of MPAN at high temperatures that affects the distribution of the MPAN reservoir (MPAN / MPA radical) reducing the fraction that can react with OH to form MAE and subsequently SOA (F(MAE formation)). The strong temperature dependence of F(MAE formation) helps to explain our observations of similar concentrations of IEPOX-derived organosulfates (IEPOX-OS; ~1 ng m(-3)) and MAE-derived organosulfates (MAE-OS; ~1 ng m(-3)) under cooler conditions (lower isoprene concentrations) and much higher IEPOX-OS (~20 ng m(-3)) relative to MAE-OS (<0.0005 ng m(-3)) at higher temperatures (higher isoprene concentrations). A kinetic model of IEPOX and MAE loss showed that MAE forms 10-100 times more ring-opening products than IEPOX and that both are strongly dependent on aerosol water content when aerosol pH is constant. However, the higher fraction of MAE ring opening products does not compensate for the lower MAE production under warmer conditions (higher isoprene concentrations) resulting in lower formation of MAE-derived products relative to IEPOX at the surface. In regions of high NOx, high isoprene emissions and strong vertical mixing the slower MPAN thermolysis rate aloft could increase the fraction of MPAN that forms MAE resulting in a vertically varying isoprene SOA source.

  6. Testing and optical modeling of novel concentrating solar receiver geometries to increase light trapping and effective solar absorptance

    NASA Astrophysics Data System (ADS)

    Yellowhair, Julius; Ho, Clifford K.; Ortega, Jesus D.; Christian, Joshua M.; Andraka, Charles E.

    2015-09-01

    Concentrating solar power receivers are comprised of panels of tubes arranged in a cylindrical or cubical shape on top of a tower. The tubes contain heat-transfer fluid that absorbs energy from the concentrated sunlight incident on the tubes. To increase the solar absorptance, black paint or a solar selective coating is applied to the surface of the tubes. However, these coatings degrade over time and must be reapplied, which reduces the system performance and increases costs. This paper presents an evaluation of novel receiver shapes and geometries that create a light-trapping effect, thereby increasing the effective solar absorptance and efficiency of the solar receiver. Several prototype shapes were fabricated from Inconel 718 and tested in Sandia's solar furnace at an irradiance of ~30 W/cm2. Photographic methods were used to capture the irradiance distribution on the receiver surfaces. The irradiance profiles were compared to results from raytracing models. The effective solar absorptance was also evaluated using the ray-tracing models. Results showed that relative to a flat plate, the new geometries could increase the effective solar absorptance from 86% to 92% for an intrinsic material absorptance of 86%, and from 60% to 73% for an intrinsic material absorptance of 60%.

  7. Coupling between absorption and scattering in disordered colloids

    NASA Astrophysics Data System (ADS)

    Stephenson, Anna; Hwang, Victoria; Park, Jin-Gyu; Manoharan, Vinothan N.

    We aim to understand how scattering and absorption are coupled in disordered colloidal suspensions containing absorbing molecules (dyes). When the absorption length is shorter than the transport length, absorption dominates, and absorption and scattering can be seen as two additive effects. However, when the transport length is shorter than the absorption length, the scattering and absorption become coupled, as multiple scattering increases the path length of the light in the sample, leading to a higher probability of absorption. To quantify this synergistic effect, we measure the diffuse reflectance spectra of colloidal samples of varying dye concentrations, thicknesses, and particle concentrations, and we calculate the transport length and absorption length from our measurements, using a radiative transfer model. At particle concentrations so high that the particles form disordered packings, we find a minimum in the transport length. We show that selecting a dye where the absorption peak matches the location of the minimum in the transport length allows for enhanced absorption. Kraft-Heinz Corporation, NSF GRFP 2015200426.

  8. Influence of CdS nanoparticles grain morphology on laser-induced absorption

    NASA Astrophysics Data System (ADS)

    Ebothé, Jean; Michel, Jean; Kityk, I. V.; Lakshminarayana, G.; Yanchuk, O. M.; Marchuk, O. V.

    2018-06-01

    Using external illumination of a 7 nanosecond (ns) doubled frequency Nd: YAG laser emitting at λ = 532 nm with frequency repetition 10 Hz it was established a possibility of significant changes of the absorption at the probing wavelength 1150 nm of continuous wave (cw) He-Ne laser for the CdS nanoparticles embedded into the PVA polymer matrix. The effect is observed only during the two beam laser coherent treatment and this effect is a consequence of interference of two coherent beams. It is shown a principal role of the grain morphology in the efficiency of the process, which is more important than the nanoparticle sizes. The photoinduced absorption is manifested in the space distribution of the probing laser beam. The principal role of the grain interfaces between the nanoparticle interfaces and the surrounding polymer matrix is shown. The effect is almost independent of the nanoparticle sizes. It may be used for laser operation by nanocomposites.

  9. Temperature dependent absorption measurement of various transition metal doped laser materials

    NASA Astrophysics Data System (ADS)

    Horackova, Lucie; Šulc, Jan; Jelinkova, Helena; Jambunathan, Venkatesan; Lucianetti, Antonio; Mocek, Tomás.

    2015-05-01

    In recent years, there has been a vast development of high energy class lasers of the order of 100 J to kJ level which have potential applications in the field of science and technology. Many such systems use the gain media cooled at cryogenic temperatures which will help in enhancing the spectroscopic and thermo-optical properties. Nevertheless, parasitic effects like amplified spontaneous emission enhance and affect the overall efficiency. The best way to suppress this effect is to use cladding element attached to the gain material. Based on these facts, this work was focused on the systematic investigation of temperature dependent absorption of several materials doped with transition metals, which can be used as cladding, as laser gain material, or as passive Q-switching element. The Ti:sapphire, Cr:YAG, V:YAG, and Co:MALO samples were measured in temperature range from 80 K to 330 K by step of 50 K. Using Beer-Lambert law we estimated the absorption coefficient of these materials.

  10. Urban impacts on regional carbonaceous aerosols: case study in central Texas.

    PubMed

    Barrett, Tate E; Sheesley, Rebecca J

    2014-08-01

    Rural and background sites provide valuable information on the concentration and optical properties of organic, elemental, and water-soluble organic carbon (OC, EC, and WSOC), which are relevant for understanding the climate forcing potential of regional atmospheric aerosols. To quantify climate- and air quality-relevant characteristics of carbonaceous aerosol in the central United States, a regional background site in central Texas was chosen for long-term measurement. Back trajectory (BT) analysis, ambient OC, EC, and WSOC concentrations and absorption parameters are reported for the first 15 months of a long-term campaign (May 2011-August 2012). BT analysis indicates consistent north-south airflow connecting central Texas to the Central Plains. Central Texas aerosols exhibited seasonal trends with increased fine particulate matter (< 2.5 microm aerodynamic diameter, PM2.5) and OC during the summer (PM2.5 = 10.9 microg m(-3) and OC = 3.0 microg m(-3)) and elevated EC during the winter (0.22 microg m(-3)). When compared to measurements in Dallas and Houston, TX, central Texas OC appears to have mixed urban and rural sources. However central Texas EC appears to be dominated by transport of urban emissions. WSOC averaged 63% of the annual OC, with little seasonal variability in this ratio. To monitor brown carbon (BrC), absorption was measured for the aqueous WSOC extracts. Light absorption coefficients for EC and BrC were highest during summer (EC MAC = 11 m2 g(-1) and BRC MAE365 = 0.15 m2 g(-1)). Results from optical analysis indicate that regional aerosol absorption is mostly due to EC with summertime peaks in BrC attenuation. This study represents the first reported values of WSOC absorption, MAE365, for the central United States. Implications: Background concentration and absorption measurements are essential in determining regional potential radiative forcing due to atmospheric aerosols. Back trajectory, chemical, and optical analysis of PM2.5 was used to

  11. Association between an unhealthy lifestyle and other factors with hypertension among hill tribe populations of Mae Fah Luang District, Chiang Rai Province, Thailand.

    PubMed

    Duangtep, Yuwadee; Narksawat, Kulaya; Chongsuwat, Rawadee; Rojanavipart, Peungchon

    2010-05-01

    An unhealthy lifestyle may lead to hypertension which can cause strokes and cardiovascular disease. The aim of this study was to identify the specific unhealthy lifestyle practices which could cause hypertension among hill tribe populations in Mae Fah Luang District of Chiang Rai Province, Thailand. In 2006, 196 patients with hypertension were selected from 2 district hospitals and 13 health centers as cases, and 196 normotensive subjects from a local neighborhood were chosen as controls. Trained health personnel collected data by interviewing subjects from both groups regarding unhealthy lifestyles and other factors. All participants had a physical examination at the time of interview. The results from multiple logistic regression analysis show the factors associated with hypertension among the hill tribe people studied were smoking (OR 2.48; 95% CI 1.43-4.30, p = 0.001), no or irregular exercise (OR 1.84; 95% CI 1.16-2.99, p = 0.005), being overweight (OR 2.96; 95% CI 1.69-5.18, p < 0.002), having obesity (OR 2.65, 95% CI 1.04-6.73, p < 0.018) and having a high frequency intake of fatty foods (OR 1.98, 95% CI 1.23-3.18, p < 0.013). The findings suggest the need for significant lifestyle changes in regards to smoking, eating habits and leisure time exercise programs. The adoption of such lifestyle changes would result in a reduced chance of being hypertensive, which could later reduce cardiovascular morbidity and mortality.

  12. Glucose absorption in acute peritoneal dialysis.

    PubMed

    Podel, J; Hodelin-Wetzel, R; Saha, D C; Burns, G

    2000-04-01

    During acute peritoneal dialysis (APD), it is known that glucose found in the dialysate solution contributes to the provision of significant calories. It has been well documented in continuous ambulatory peritoneal dialysis (CAPD) that glucose absorption occurs. In APD, however, it remains unclear how much glucose absorption actually does occur. Therefore, the purpose of this study was to determine whether it is appropriate to use the formula used to calculate glucose absorption in CAPD (Grodstein et al) among patients undergoing APD. Actual measurements of glucose absorption (Method I) were calculated in 9 patients undergoing APD treatment for >24 hours who were admitted to the intensive care unit. Glucose absorption using the Grodstein et al formula (Method II) was also determined and compared with the results of actual measurements. The data was then further analyzed based on the factors that influence glucose absorption, specifically dwell time and concentration. The mean total amount of glucose absorbed was 43% +/- 15%. However, when dwell time and concentration were further examined, significant differences were noted. Method I showed a cumulative increase over time. Method II showed that absorption was fixed. This suggests that with the variation in dwell time commonly seen in the acute care setting, the use of Method II may not be accurate. In each of the 2 methods, a significant difference in glucose absorption was noted when comparing the use of 1.5% and 4.25% dialysate concentrations. The established formula designed for CAPD should not be used for calculating glucose absorption in patients receiving APD because variation in dwell time and concentration should be taken into account. Because of the time constraints and staffing required to calculate each exchange individually, combined with the results of the study, we recommend the use of the percentage estimate of 40% to 50%.

  13. Green extraction of grape skin phenolics by using deep eutectic solvents.

    PubMed

    Cvjetko Bubalo, Marina; Ćurko, Natka; Tomašević, Marina; Kovačević Ganić, Karin; Radojčić Redovniković, Ivana

    2016-06-01

    Conventional extraction techniques for plant phenolics are usually associated with high organic solvent consumption and long extraction times. In order to establish an environmentally friendly extraction method for grape skin phenolics, deep eutectic solvents (DES) as a green alternative to conventional solvents coupled with highly efficient microwave-assisted and ultrasound-assisted extraction methods (MAE and UAE, respectively) have been considered. Initially, screening of five different DES for proposed extraction was performed and choline chloride-based DES containing oxalic acid as a hydrogen bond donor with 25% of water was selected as the most promising one, resulting in more effective extraction of grape skin phenolic compounds compared to conventional solvents. Additionally, in our study, UAE proved to be the best extraction method with extraction efficiency superior to both MAE and conventional extraction method. The knowledge acquired in this study will contribute to further DES implementation in extraction of biologically active compounds from various plant sources. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Efficiency Improvement of Some Agricultural Residue Modified Materials for Textile Dyes Absorption

    NASA Astrophysics Data System (ADS)

    Boonsong, P.; Paksamut, J.

    2018-03-01

    In this work, the adsorption efficiency was investigated of some agricultural residue modified materials as natural bio-adsorbents which were rice straw (Oryza sativa L.) and pineapple leaves (Ananas comosus (L.) Merr.) for the removal of textile dyes. Reactive dyes were used in this research. The improvement procedure of agricultural residue materials properties were alkali-acid modification with sodium hydroxide solution and hydrochloric acid solution. Adsorption performance has been investigated using batch experiments. Investigated adsorption factors consisted of adsorbent dose, contact time, adsorbent materials and pH of solution. The results were found that rice straw had higher adsorption capacity than pineapple leaves. The increasing of adsorption capacity depends on adsorbent dose and contact time. Moreover, the optimum pH for dye adsorption was acidic range because lowering pH increased the positively charges on the adsorbent surface which could be attacked by negatively charge of acid dyes. The agricultural residue modified materials had significant dye removal efficiency which these adsorbents could be used for the treatment of textile effluent in industries.

  15. The Effects of Triggering Mechanisms on the Energy Absorption Capability of Circular Jute/Epoxy Composite Tubes under Quasi-Static Axial Loading

    NASA Astrophysics Data System (ADS)

    Sivagurunathan, Rubentheran; Lau Tze Way, Saijod; Sivagurunathan, Linkesvaran; Yaakob, Mohd. Yuhazri

    2018-01-01

    The usage of composite materials have been improving over the years due to its superior mechanical properties such as high tensile strength, high energy absorption capability, and corrosion resistance. In this present study, the energy absorption capability of circular jute/epoxy composite tubes were tested and evaluated. To induce the progressive crushing of the composite tubes, four different types of triggering mechanisms were used which were the non-trigger, single chamfered trigger, double chamfered trigger and tulip trigger. Quasi-static axial loading test was carried out to understand the deformation patterns and the load-displacement characteristics for each composite tube. Besides that, the influence of energy absorption, crush force efficiency, peak load, mean load and load-displacement history were examined and discussed. The primary results displayed a significant influence on the energy absorption capability provided that stable progressive crushing occurred mostly in the triggered tubes compared to the non-triggered tubes. Overall, the tulip trigger configuration attributed the highest energy absorption.

  16. Directional power absorption in helicon plasma sources excited by a half-helix antenna

    NASA Astrophysics Data System (ADS)

    Afsharmanesh, Mohsen; Habibi, Morteza

    2017-10-01

    This paper deals with the investigation of the power absorption in helicon plasma excited through a half-helix antenna driven at 13.56 {{MHz}}. The simulations were carried out by means of a code, HELIC. They were carried out by taking into account different inhomogeneous radial density profiles and for a wide range of plasma densities, from {10}11 {{{cm}}}-3 to {10}13 {{{cm}}}-3. The magnetic field was 200, 400, 600 and 1000 {{G}}. A three-parameter function was used for generating various density profiles with different volume gradients, edge gradients and density widths. The density profile had a large effect on the efficient Trivelpiece-Gould (TG) and helicon mode excitation and antenna coupling to the plasma. The fraction of power deposition via the TG mode was extremely dependent on the plasma density near the plasma boundary. Interestingly, the obtained efficient parallel helicon wavelength was close to the anticipated value for Gaussian radial density profile. Power deposition was considerably asymmetric when the \\tfrac{n}{{B}0} ratio was more than a specific value for a determined density width. The longitudinal power absorption was symmetric at approximately {n}0={10}11 {{{cm}}}-3, irrespective of the magnetic field supposed. The asymmetry became more pronounced when the plasma density was {10}12 {{{cm}}}-3. The ratio of density width to the magnetic field was an important parameter in the power coupling. At high magnetic fields, the maximum of the power absorption was reached at higher plasma density widths. There was at least one combination of the plasma density, magnetic field and density width for which the RF power deposition at both side of the tube reached its maximum value.

  17. Design of coated standing nanowire array solar cell performing beyond the planar efficiency limits

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

    Zeng, Yang; Ye, Qinghao; Shen, Wenzhong, E-mail: wzshen@sjtu.edu.cn

    2016-05-28

    The single standing nanowire (SNW) solar cells have been proven to perform beyond the planar efficiency limits in both open-circuit voltage and internal quantum efficiency due to the built-in concentration and the shifting of the absorption front. However, the expandability of these nano-scale units to a macro-scale photovoltaic device remains unsolved. The main difficulty lies in the simultaneous preservation of an effective built-in concentration in each unit cell and a broadband high absorption capability of their array. Here, we have provided a detailed theoretical guideline for realizing a macro-scale solar cell that performs furthest beyond the planar limits. The keymore » lies in a complementary design between the light-trapping of the single SNWs and that of the photonic crystal slab formed by the array. By tuning the hybrid HE modes of the SNWs through the thickness of a coaxial dielectric coating, the optimized coated SNW array can sustain an absorption rate over 97.5% for a period as large as 425 nm, which, together with the inherited carrier extraction advantage, leads to a cell efficiency increment of 30% over the planar limit. This work has demonstrated the viability of a large-size solar cell that performs beyond the planar limits.« less

  18. Design of a graphene-based dual-slot hybrid plasmonic electro-absorption modulator with high-modulation efficiency and broad optical bandwidth for on-chip communication.

    PubMed

    Wu, Zhongwei; Xu, Yin

    2018-04-20

    The hybrid plasmonic effect with lower loss and comparable light confinement than surface plasmon polariton opens new avenues for strengthening light-matter interactions with low loss. Here, we propose and numerically analyze a graphene-based electro-absorption modulator (EAM) with high-modulation efficiency and broad optical bandwidth using a dual-slot hybrid plasmonic waveguide (HPW), which consists of a central dual-slot HPW connected with two taper transitions and two additional dual-slot HPWs for coupling it with the input and output silicon nanowires, where graphene layers are located at the bottom and top side of the whole dual-slot HPW region. By combining the huge light enhancement effect of the dual-slot HPW and graphene's tunable conductivity, we obtain a high-modulation efficiency (ME) of 1.76 dB/μm for the graphene-based dual-slot HPW (higher ME of 2.19 dB/μm can also be obtained). Based upon this promising result, we further design a graphene-based hybrid plasmonic EAM, achieving a modulation depth (MD) of 15.95 dB and insertion loss of 1.89 dB @1.55 μm, respectively, in a total length of only 10 μm, where its bandwidth can reach over 500 nm for keeping MD>15  dB; MD can also be improved by slightly increasing the device length or shrinking the waveguide thickness, showing strong advantages for applying it into on-chip high-performance silicon modulators.

  19. Influence of formulation and processing on absorption and metabolism of flavan-3-ols from tea and cocoa.

    PubMed

    Neilson, Andrew P; Ferruzzi, Mario G

    2011-01-01

    Flavan-3-ols are a major subclass of the class of plant phytochemicals known as flavonoids. Flavan-3-ols are commonly found in fruit, vegetable, and botanical products, including tea, cocoa, grapes, and apples. Both monomeric catechins and polymeric procyanidins are common in the diet, along with several derivatives produced by degradation of these species during processing. Both epidemiological and biological evidence suggests a health-protective role for dietary flavan-3-ols, leading to increased interest in the bioavailability of these compounds from foods. Flavan-3-ol bioavailability depends on numerous factors, including digestive release, absorption, metabolism, and elimination. In addition to these in vivo factors, the complexity of whole-food systems (physical form, flavan-3-ol form and dose, macronutrient and micronutrient profile, processing, etc.) influences the absorption efficiency and circulating profile of flavan-3-ols. An understanding of how food matrices may influence flavan-3-ol absorption will provide a framework to design and develop functional products that positively affect flavan-3-ol absorption and, by extension, potential bioactivity.

  20. Absorption-emission optrode and methods of use thereof

    DOEpatents

    Hirschfeld, T.B.

    1990-05-29

    A method and apparatus are described for monitoring the physical and chemical properties of a sample fluid by measuring an optical signal generated by a fluorescent substance and modulated by an absorber substance. The emission band of the fluorescent substance overlaps the absorption band of the absorber substance, and the degree of overlap is dependent on the physical and chemical properties of the sample fluid. The fluorescent substance and absorber substance are immobilized on a substrate so that an effective number of molecules thereof are sufficiently close for resonant energy transfer to occur, thereby providing highly efficient modulation of the fluorescent emissions of the fluorescent substance by the absorber substance. 4 figs.