Quantitative analysis of phosphoinositide 3-kinase (PI3K) signaling using live-cell total internal reflection fluorescence (TIRF) microscopy.

PubMed

Johnson, Heath E; Haugh, Jason M

2013-12-02

This unit focuses on the use of total internal reflection fluorescence (TIRF) microscopy and image analysis methods to study the dynamics of signal transduction mediated by class I phosphoinositide 3-kinases (PI3Ks) in mammalian cells. The first four protocols cover live-cell imaging experiments, image acquisition parameters, and basic image processing and segmentation. These methods are generally applicable to live-cell TIRF experiments. The remaining protocols outline more advanced image analysis methods, which were developed in our laboratory for the purpose of characterizing the spatiotemporal dynamics of PI3K signaling. These methods may be extended to analyze other cellular processes monitored using fluorescent biosensors. Copyright © 2013 John Wiley & Sons, Inc.

Aerosol Optical Depth Retrievals From High-Resolution Commercial Satellite Imagery Over Areas of High Surface Reflectance

NASA Astrophysics Data System (ADS)

Vincent, D. A.; Nielsen, K. E.; Durkee, P. A.; Reid, J. S.

2005-12-01

The advancement and proliferation of high-resolution commercial imaging satellites presents a new opportunity for overland aerosol characterization. Current aerosol optical depth retrieval methods typically fail over areas with high surface reflectance, such as urban areas and deserts, since the upwelling radiance due to scattering by aerosols is small compared to the radiance resulting from surface reflection. The method proposed here uses shadows cast on the surface to exploit the differences between radiance from the adjacent shaded and unshaded areas of the scene. Shaded areas of the scene are primarily illuminated by diffuse irradiance that is scattered downward from the atmosphere, while unshaded areas are illuminated by both diffuse and direct solar irradiance. The first-order difference between the shaded and unshaded areas is the direct component. Given uniform surface reflectance for the shaded and unshaded areas, the difference in reflected radiance measured by a satellite sensor is related to the direct transmission of solar radiation and inversely proportional to total optical depth. Using an iterative approach, surface reflectance and mean aerosol reflectance can be partitioned to refine the retrieved total optical depth. Aerosol optical depth can then be determined from its contribution to the total atmospheric optical depth (following correction for molecular Rayleigh scattering). Intitial results based on QuickBird imagery and AERONET data collected during the United Arab Emirates Unified Aerosol Experiment (UAE2) indicate that aerosol optical depth retrievals are possible in the visible and near-infrared region with an accuracy of ~0.04.

The infrared bands Pechan prism axis parallel detection method

NASA Astrophysics Data System (ADS)

Qiang, Hua; Ji, Ming; He, Yu-lan; Wang, Nan-xi; Chang, Wei-jun; Wang, Ling; Liu, Li

2017-02-01

In this paper, we put forward a new method to adjust the air gap of the total reflection air gap of the infrared Pechan prism. The adjustment of the air gap in the air gap of the Pechan prism directly affects the parallelism of the optical axis, so as to affect the consistency of the optical axis of the infrared system. The method solves the contradiction between the total reflection and the high transmission of the infrared wave band, and promotes the engineering of the infrared wave band. This paper puts forward the method of adjusting and controlling, which can ensure the full reflection and high penetration of the light, and also can accurately measure the optical axis of the optical axis of the different Pechan prism, and can achieve the precision of the level of the sec. For Pechan prism used in the infrared band image de rotation, make the product to realize miniaturization, lightweight plays an important significance.

Use of borehole radar reflection logging to monitor steam-enhanced remediation in fractured limestone-results of numerical modelling and a field experiment

USGS Publications Warehouse

Gregoire, C.; Joesten, P.K.; Lane, J.W.

2006-01-01

Ground penetrating radar is an efficient geophysical method for the detection and location of fractures and fracture zones in electrically resistive rocks. In this study, the use of down-hole (borehole) radar reflection logs to monitor the injection of steam in fractured rocks was tested as part of a field-scale, steam-enhanced remediation pilot study conducted at a fractured limestone quarry contaminated with chlorinated hydrocarbons at the former Loring Air Force Base, Limestone, Maine, USA. In support of the pilot study, borehole radar reflection logs were collected three times (before, during, and near the end of steam injection) using broadband 100 MHz electric dipole antennas. Numerical modelling was performed to predict the effect of heating on radar-frequency electromagnetic (EM) wave velocity, attenuation, and fracture reflectivity. The modelling results indicate that EM wave velocity and attenuation change substantially if heating increases the electrical conductivity of the limestone matrix. Furthermore, the net effect of heat-induced variations in fracture-fluid dielectric properties on average medium velocity is insignificant because the expected total fracture porosity is low. In contrast, changes in fracture fluid electrical conductivity can have a significant effect on EM wave attenuation and fracture reflectivity. Total replacement of water by steam in a fracture decreases fracture reflectivity of a factor of 10 and induces a change in reflected wave polarity. Based on the numerical modelling results, a reflection amplitude analysis method was developed to delineate fractures where steam has displaced water. Radar reflection logs collected during the three acquisition periods were analysed in the frequency domain to determine if steam had replaced water in the fractures (after normalizing the logs to compensate for differences in antenna performance between logging runs). Analysis of the radar reflection logs from a borehole where the temperature increased substantially during the steam injection experiment shows an increase in attenuation and a decrease in reflectivity in the vicinity of the borehole. Results of applying the reflection amplitude analysis method developed for this study indicate that steam did not totally replace the water in most of the fractures. The observed decreases in reflectivity were consistent with an increase in fracture-water temperature, rather than the presence of steam. A limiting assumption of the reflection amplitude analysis method is the requirement for complete displacement of water in a fracture by steam. ?? 2006 Elsevier B.V. All rights reserved.

Preliminary Method for Direct Quantification of Colistin Methanesulfonate by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

PubMed Central

Niece, Krista L.

2015-01-01

Colistin use has increased in response to the advent of infections caused by multidrug-resistant organisms. It is administered parenterally as an inactive prodrug, colistin methanesulfonate (CMS). Various formulations of CMS and labeling conventions can lead to confusion about colistin dosing, and questions remain about the pharmacokinetics of CMS. Since CMS does not have strong UV absorbance, current methods employ a laborious process of chemical conversion to colistin followed by precolumn derivatization to detect formed colistin by high-performance liquid chromatography. Here, we report a method for direct quantification of colistin methanesulfonate by attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR). PMID:26124160

A study of muscular tissue of animal origin by reflection-spectroscopy methods

NASA Astrophysics Data System (ADS)

Plotnikova, L. V.; Nechiporenko, A. P.; Orekhova, S. M.; Plotnikov, P. P.; Ishevskii, A. L.

2017-06-01

A comparative analysis of the spectral characteristics of the surface of muscular tissue of animal origin (pork) and its main components has been performed by the methods of diffuse reflection electronic spectroscopy (DRES) and frustrated total internal reflection IR spectroscopy. The experiments have shown that the application of the DRES method makes it possible to detect more pronounced changes in the surface optical characteristics of muscular tissue and obtain electronic spectra containing information about the component composition of its main parts under successive extraction of sarcoplasmic materials, myofibrillar proteins of the actomyosin complex, and stroma mucopolysaccharides.

Application of the Total Reflection X-ray Fluorescence technique to trace elements determination in tobacco

NASA Astrophysics Data System (ADS)

Martinez, T.; Lartigue, J.; Zarazua, G.; Avila-Perez, P.; Navarrete, M.; Tejeda, S.

2008-12-01

Many studies have identified an important number of toxic elements along with organic carcinogen molecules and radioactive isotopes in tobacco. In this work we have analyzed by Total Reflection X-Ray Fluorescence 9 brands of cigarettes being manufactured and distributed in the Mexican market. Two National Institute of Standards and Technology standards and a blank were equally treated at the same time. Results show the presence of some toxic elements such as Pb and Ni. These results are compared with available data for some foreign brands, while their implications for health are discussed. It can be confirmed that the Total Reflection X-Ray Fluorescence method provides precise (reproducible) and accuracy (trueness) data for 15 elements concentration in tobacco samples.

Terahertz time-domain attenuated total reflection spectroscopy applied to the rapid discrimination of the botanical origin of honeys

NASA Astrophysics Data System (ADS)

Liu, Wen; Zhang, Yuying; Yang, Si; Han, Donghai

2018-05-01

A new technique to identify the floral resources of honeys is demanded. Terahertz time-domain attenuated total reflection spectroscopy combined with chemometrics methods was applied to discriminate different categorizes (Medlar honey, Vitex honey, and Acacia honey). Principal component analysis (PCA), cluster analysis (CA) and partial least squares-discriminant analysis (PLS-DA) have been used to find information of the botanical origins of honeys. Spectral range also was discussed to increase the precision of PLS-DA model. The accuracy of 88.46% for validation set was obtained, using PLS-DA model in 0.5-1.5 THz. This work indicated terahertz time-domain attenuated total reflection spectroscopy was an available approach to evaluate the quality of honey rapidly.

Study on grain quality forecasting method and indicators by using hyperspectral data in wheat

NASA Astrophysics Data System (ADS)

Huang, Wenjiang; Wang, Jihua; Liu, Liangyun; Wang, Zhijie; Tan, Changwei; Song, Xiaoyu; Wang, Jingdi

2005-01-01

Field experiments were conducted to examine the influence factors of cultivar, nitrogen application and irrigation on grain protein content, gluten content and grain hardness in three winter wheat cultivars under four levels of nitrogen and irrigation treatments. Firstly, the influence of cultivars and environment factors on grain quality were studied, the effective factors were cultivars, irrigation, fertilization, et al. Secondly, total nitrogen content around winter wheat anthesis stage was proved to be significant correlative with grain protein content, and spectral vegetation index significantly correlated to total nitrogen content around anthesis stage were the potential indicators for grain protein content. Accumulation of total nitrogen content and its transfer to grain is the physical link to produce the final grain protein, and total nitrogen content at anthesis stage was proved to be an indicator of final grain protein content. The selected normalized photochemical reflectance index (NPRI) was proved to be able to predict of grain protein content on the close correlation between the ratio of total carotenoid to chlorophyll a and total nitrogen content. The method contributes towards developing optimal procedures for predicting wheat grain quality through analysis of their canopy reflected spectrum at anthesis stage. Regression equations were established for forecasting grain protein and dry gluten content by total nitrogen content at anthesis stage, so it is feasible for forecasting grain quality by establishing correlation equations between biochemical constitutes and canopy reflected spectrum.

A simple method to measure critical angles for high-sensitivity differential refractometry.

PubMed

Zilio, S C

2012-01-16

A total internal reflection-based differencial refractometer, capable of measuring the real and imaginary parts of the complex refractive index in real time, is presented. The device takes advantage of the phase difference acquired by s- and p-polarized light to generate an easily detectable minimum at the reflected profile. The method allows to sensitively measuring transparent and turbid liquid samples.

Three-dimensional particle tracking in concave structures made by ultraviolet nanoimprint via total internal reflection fluorescence microscopy and refractive-index-matching method

NASA Astrophysics Data System (ADS)

Fujinami, Taku; Kigami, Hiroshi; Unno, Noriyuki; Taniguchi, Jun; Satake, Shin-ichi

2018-06-01

Total internal reflection fluorescence microscopy (TIRFM) is a promising method for measuring fluid flow close to a wall with nanoscale resolution in a process that is termed "multilayer nanoparticle image velocimetry" (MnPIV). TIRFM uses evanescent light that is generated on a substrate (typically a glass slide) by total internal reflection of light. Many researchers have previously studied x- y- z (3D) flows of water close to flat glass slides using MnPIV. On the other hand, a fluid flow close to a structured surface is also important. To measure flows of water near micro-patterns, we previously developed an MnPIV technique that uses a refractive-index-matching method. In previous study, the micropattern is made of a thermoplastic material with a refractive index that closely matches that of water. In this study, ultraviolet nanoimprint lithography was used for fabricating the appropriate micro-patterns because this technique can fabricate a pattern with a high resolution. As a result, we succeeded in performing MnPIV in water with a circular hole array pattern made by ultraviolet nanoimprint using a refractive-index-matching method. We believe that this technique will be helpful in elucidating fluid flows around microstructures.

Three-dimensional particle tracking in concave structures made by ultraviolet nanoimprint via total internal reflection fluorescence microscopy and refractive-index-matching method

NASA Astrophysics Data System (ADS)

Fujinami, Taku; Kigami, Hiroshi; Unno, Noriyuki; Taniguchi, Jun; Satake, Shin-ichi

2018-03-01

Total internal reflection fluorescence microscopy (TIRFM) is a promising method for measuring fluid flow close to a wall with nanoscale resolution in a process that is termed "multilayer nanoparticle image velocimetry" (MnPIV). TIRFM uses evanescent light that is generated on a substrate (typically a glass slide) by total internal reflection of light. Many researchers have previously studied x-y-z (3D) flows of water close to flat glass slides using MnPIV. On the other hand, a fluid flow close to a structured surface is also important. To measure flows of water near micro-patterns, we previously developed an MnPIV technique that uses a refractive-index-matching method. In previous study, the micropattern is made of a thermoplastic material with a refractive index that closely matches that of water. In this study, ultraviolet nanoimprint lithography was used for fabricating the appropriate micro-patterns because this technique can fabricate a pattern with a high resolution. As a result, we succeeded in performing MnPIV in water with a circular hole array pattern made by ultraviolet nanoimprint using a refractive-index-matching method. We believe that this technique will be helpful in elucidating fluid flows around microstructures.

Surface albedo from bidirectional reflectance

NASA Technical Reports Server (NTRS)

Ranson, K. J.; Irons, J. R.; Daughtry, C. S. T.

1991-01-01

The validity of integrating over discrete wavelength bands is examined to estimate total shortwave bidirectional reflectance of vegetated and bare soil surfaces. Methods for estimating albedo from multiple angle, discrete wavelength band radiometer measurements are studied. These methods include a numerical integration technique and the integration of an empirically derived equation for bidirectional reflectance. It is concluded that shortwave albedos estimated through both techniques agree favorably with the independent pyranometer measurements. Absolute rms errors are found to be 0.5 percent or less for both grass sod and bare soil surfaces.

Fast determination of total ginsenosides content in ginseng powder by near infrared reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Chen, Hua-cai; Chen, Xing-dan; Lu, Yong-jun; Cao, Zhi-qiang

2006-01-01

Near infrared (NIR) reflectance spectroscopy was used to develop a fast determination method for total ginsenosides in Ginseng (Panax Ginseng) powder. The spectra were analyzed with multiplicative signal correction (MSC) correlation method. The best correlative spectra region with the total ginsenosides content was 1660 nm~1880 nm and 2230nm~2380 nm. The NIR calibration models of ginsenosides were built with multiple linear regression (MLR), principle component regression (PCR) and partial least squares (PLS) regression respectively. The results showed that the calibration model built with PLS combined with MSC and the optimal spectrum region was the best one. The correlation coefficient and the root mean square error of correction validation (RMSEC) of the best calibration model were 0.98 and 0.15% respectively. The optimal spectrum region for calibration was 1204nm~2014nm. The result suggested that using NIR to rapidly determinate the total ginsenosides content in ginseng powder were feasible.

Application of reflectance spectroscopies (FTIR-ATR & FT-NIR) coupled with multivariate methods for robust in vivo detection of begomovirus infection in papaya leaves

NASA Astrophysics Data System (ADS)

Haq, Quazi M. I.; Mabood, Fazal; Naureen, Zakira; Al-Harrasi, Ahmed; Gilani, Sayed A.; Hussain, Javid; Jabeen, Farah; Khan, Ajmal; Al-Sabari, Ruqaya S. M.; Al-khanbashi, Fatema H. S.; Al-Fahdi, Amira A. M.; Al-Zaabi, Ahoud K. A.; Al-Shuraiqi, Fatma A. M.; Al-Bahaisi, Iman M.

2018-06-01

Nucleic acid & serology based methods have revolutionized plant disease detection, however, they are not very reliable at asymptomatic stage, especially in case of pathogen with systemic infection, in addition, they need at least 1-2 days for sample harvesting, processing, and analysis. In this study, two reflectance spectroscopies i.e. Near Infrared reflectance spectroscopy (NIR) and Fourier-Transform-Infrared spectroscopy with Attenuated Total Reflection (FT-IR, ATR) coupled with multivariate exploratory methods like Principle Component Analysis (PCA) and Partial least square discriminant analysis (PLS-DA) have been deployed to detect begomovirus infection in papaya leaves. The application of those techniques demonstrates that they are very useful for robust in vivo detection of plant begomovirus infection. These methods are simple, sensitive, reproducible, precise, and do not require any lengthy samples preparation procedures.

Development of a method for the determination of Fusarium fungi on corn using mid-infrared spectroscopy with attenuated total reflection and chemometrics.

PubMed

Kos, Gregor; Lohninger, Hans; Krska, Rudolf

2003-03-01

A novel method, which enables the determination of fungal infection with Fusarium graminearum on corn within minutes, is presented. The ground sample was sieved and the particle size fraction between >250 and 100 microm was used for mid-infrared/attenuated total reflection (ATR) measurements. The sample was pressed onto the ATR crystal, and reproducible pressure was applied. After the spectra were recorded, they were subjected to principle component analysis (PCA) and classified using cluster analysis. Observed changes in the spectra reflected changes in protein, carbohydrate, and lipid contents. Ergosterol (for the total fungal biomass) and the toxin deoxynivalenol (DON; a secondary metabolite) of Fusarium fungi served as reference parameters, because of their relevance for the examination of corn based food and feed. The repeatability was highly improved by sieving prior to recording the spectra, resulting in a better clustering in PCA score/score plots. The developed method enabled the separation of samples with a toxin content of as low as 310 microg/kg from noncontaminated (blank) samples. Investigated concentration ranges were 880-3600 microg/kg for ergosterol and 310-2596 microg/kg for DON. The percentage of correctly classified samples was up to 100% for individual samples compared with a number of blank samples.

Impulsive solar X-ray bursts. III - Polarization, directivity, and spectrum of the reflected and total bremsstrahlung radiation from a beam of electrons directed toward the photosphere

NASA Technical Reports Server (NTRS)

Langer, S. H.; Petrosian, V.

1977-01-01

The paper presents the spectrum, directivity, and state of polarization of the bremsstrahlung radiation expected from a beam of high-energy electrons spiraling along radial magnetic field lines toward the photosphere. A Monte Carlo method is then described for evaluation of the spectrum, directivity, and polarization of X-rays diffusely reflected from stellar photospheres. The accuracy of the technique is evaluated through comparison with analytic results. The calculated characteristics of the incident X-rays are used to evaluate the spectrum, directivity, and polarization of the reflected and total X-ray fluxes. The results are compared with observations.

Facilitating Dental Student Reflections: Using Mentor Groups to Discuss Clinical Experiences and Personal Development.

PubMed

Koole, Sebastiaan; Christiaens, Veronique; Cosyn, Jan; De Bruyn, Hugo

2016-10-01

Despite the consensus on the importance of reflection for dental professionals, a lack of understanding remains about how students and clinicians should develop their ability to reflect. The aim of this study was to investigate dental students' and mentors' perceptions of mentor groups as an instructional method to facilitate students' reflection in terms of the strategy's learning potential, role of the mentor, group dynamics, and feasibility. At Ghent University in Belgium, third- and fourth-year dental students were encouraged to reflect on their clinical experiences and personal development in three reflective mentor sessions. No preparation or reports afterwards were required; students needed only to participate in the sessions. Sessions were guided by trained mentors to establish a safe environment, frame clinical discussions, and stimulate reflection. Students' and mentors' perceptions of the experience were assessed with a 17-statement questionnaire with response options on a five-point Likert scale (1=totally disagree to 5=totally agree). A total of 50 students and eight mentors completed the questionnaire (response rates 81% and 89%, respectively). Both students and mentors had neutral to positive perceptions concerning the learning potential, role of the mentor, group dynamics, and feasibility. The mean ideal total time for sessions in a year was 99 minutes (third-year students), 111 minutes (fourth-year students), and 147 minutes (mentors). Reported reflective topics related to patient management, frustrations, and practice of dentistry. Overall mean appreciation for the experience ranged from 14.50 to 15.14 on the 20-point scale. These findings about students' and mentors' positive perceptions of the experience suggest that mentor groups may be a potentially valuable strategy to promote dental students' reflection.

Nondispersive neutron focusing method beyond the critical angle of mirrors

DOEpatents

Ice, Gene E.

2008-10-21

This invention extends the Kirkpatrick-Baez (KB) mirror focusing geometry to allow nondispersive focusing of neutrons with a convergence on a sample much larger than is possible with existing KB optical schemes by establishing an array of at least three mirrors and focusing neutrons by appropriate multiple deflections via the array. The method may be utilized with supermirrors, multilayer mirrors, or total external reflection mirrors. Because high-energy x-rays behave like neutrons in their absorption and reflectivity rates, this method may be used with x-rays as well as neutrons.

Genome-wide association mapping of soybean chlorophyll traits based on canopy spectral reflectance and leaf extracts.

PubMed

Dhanapal, Arun Prabhu; Ray, Jeffery D; Singh, Shardendu K; Hoyos-Villegas, Valerio; Smith, James R; Purcell, Larry C; Fritschi, Felix B

2016-08-04

Chlorophyll is a major component of chloroplasts and a better understanding of the genetic basis of chlorophyll in soybean [Glycine max (L.) Merr.] might contribute to improving photosynthetic capacity and yield in regions with adverse environmental conditions. A collection of 332 diverse soybean genotypes were grown in 2 years (2009 and 2010) and chlorophyll a (eChl_A), chlorophyll b (eChl_B), and total chlorophyll (eChl_T) content as well as chlorophyll a/b ratio (eChl_R) in leaf tissues were determined by extraction and spectrometric determination. Total chlorophyll was also derived from canopy spectral reflectance measurements using a model of wavelet transformed spectra (tChl_T) as well as with a spectral reflectance index (iChl_T). A genome-wide associating mapping approach was employed using 31,253 single nucleotide polymorphisms (SNPs) to identify loci associated with the extract based eChl_A, eChl_B, eChl_R and eChl_T measurements and the two canopy spectral reflectance-based methods (tChl_T and iChl_T). A total of 23 (14 loci), 15 (7 loci) and 14 SNPs (10 loci) showed significant association with eChl_A, eChl_B and eChl_R respectively. A total of 52 unique SNPs were significantly associated with total chlorophyll content based on at least one of the three approaches (eChl_T, tChl_T and iChl_T) and likely tagged 27 putative loci for total chlorophyll content, four of which were indicated by all three approaches. Results presented here show that markers for chlorophyll traits can be identified in soybean using both extract-based and canopy spectral reflectance-based phenotypes, and confirm that high-throughput phenotyping-amenable canopy spectral reflectance measurements can be used for association mapping.

Use of complex frequency plane to design broadband and sub-wavelength absorbers.

PubMed

Romero-García, V; Theocharis, G; Richoux, O; Pagneux, V

2016-06-01

The reflection of sound of frequency below 1 kHz, by a rigid-backed structure that contains sub-wavelength resonators is studied in this work. In particular, only single mode reflected waves are considered, an approximation which is accurate in this low frequency regime. A method of analysis of absorption that uses the structure of the reflection coefficient in the complex frequency plane is proposed. In the absence of losses, the reflection coefficient supports pairs of poles and zeros that are complex conjugate and which have imaginary parts linked to the energy leakage by radiation. When losses are introduced and balanced to the leakage, the critical coupling condition is satisfied and total absorption is obtained. Examples of a slot resonator and of multiple Helmholtz resonators are analyzed to obtain both narrow and broadband total absorption.

Comparative evaluation of neonatal bilirubin using Radiometer whole blood co-oximetry and plasma bilirubin methods from Roche Diagnostics and Ortho Clinical Diagnostics.

PubMed

Lano, Ian Marie; Lyon, Andrew W; Wang, Li; Ruskin, Rob; Lyon, Martha E

2018-03-01

Clinically significant variation has been reported within and between plasma and whole blood total bilirubin methods used to identify neonates for whom clinical intervention for hyperbilirubinemia may be required. To evaluate total bilirubin measurements between the Radiometer whole blood co-oximeter and plasma bilirubin methods from Roche Diagnostics and Ortho Clinical Diagnostics using neonatal specimens. Total bilirubin levels were analyzed by whole blood co-oximetry (Radiometer® ABL90). Specimens were centrifuged and plasma analyzed for total bilirubin with a diazo method (Roche Cobas® C-601) and a reflectance spectrophotometric BuBc dry film method (Ortho Clinical Diagnostics VITROS® 350). Results were evaluated by regression, Bland-Altman comparisons and t-tests. The patient correlation study yielded the following regression equations in μmol/L: a) Radiometer=1.03 Roche - 3.5μmol/L b) Radiometer=0.98 Ortho - 5.7μmol/L c) Roche=0.97 Ortho - 2.4μmol/L. The mean bias over the range of total bilirubin levels examined was -1.0μmol/L for the Radiometer versus the Roche (p≤0.305); -4.4μmol/L for the Radiometer versus Ortho (p≤0.005) and -4.4μmol/L for the Roche versus Ortho (p≤0.002). Whole blood total bilirubin measurement using the Radiometer ABL90 blood gas analyzer provides accurate and precise results compared to the Roche plasma diazo method. Compared to the reflectance spectrophotometric method, results are precise and had a small but statistically significant bias of -4.4μmol/L. Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Artifact Correction in Temperature-Dependent Attenuated Total Reflection Infrared (ATR-IR) Spectra.

PubMed

Sobieski, Brian; Chase, Bruce; Noda, Isao; Rabolt, John

2017-08-01

A spectral processing method was developed and tested for analyzing temperature-dependent attenuated total reflection infrared (ATR-IR) spectra of aliphatic polyesters. Spectra of a bio-based, biodegradable polymer, 3.9 mol% 3HHx poly[(R)-3-hydroxybutyrate- co-(R)-3-hydroxyhexanoate] (PHBHx), were analyzed and corrected prior to analysis using two-dimensional correlation spectroscopy (2D-COS). Removal of the temperature variation of diamond absorbance, correction of the baseline, ATR correction, and appropriate normalization were key to generating more reliable data. Both the processing steps and order were important. A comparison to differential scanning calorimetry (DSC) analysis indicated that the normalization method should be chosen with caution to avoid unintentional trends and distortions of the crystalline sensitive bands.

Estimating soil water evaporation using radar measurements

NASA Technical Reports Server (NTRS)

Sadeghi, Ali M.; Scott, H. D.; Waite, W. P.; Asrar, G.

1988-01-01

Field studies were conducted to evaluate the application of radar reflectivity as compared with the shortwave reflectivity (albedo) used in the Idso-Jackson equation for the estimation of daily evaporation under overcast sky and subhumid climatic conditions. Soil water content, water potential, shortwave and radar reflectivity, and soil and air temperatures were monitored during three soil drying cycles. The data from each cycle were used to calculate daily evaporation from the Idso-Jackson equation and from two other standard methods, the modified Penman and plane of zero-flux. All three methods resulted in similar estimates of evaporation under clear sky conditions; however, under overcast sky conditions, evaporation fluxes computed from the Idso-Jackson equation were consistently lower than the other two methods. The shortwave albedo values in the Idso-Jackson equation were then replaced with radar reflectivities and a new set of total daily evaporation fluxes were calculated. This resulted in a significant improvement in computed soil evaporation fluxes from the Idso-Jackson equation, and a better agreement between the three methods under overcast sky conditions.

One-step Maskless Fabrication and Optical Characterization of Silicon Surfaces with Antireflective Properties and a White Color Appearance

PubMed Central

Schneider, Ling; Feidenhans’l, Nikolaj A.; Telecka, Agnieszka; Taboryski, Rafael J.

2016-01-01

We report a simple one-step maskless fabrication of inverted pyramids on silicon wafers by reactive ion etching. The fabricated surface structures exhibit excellent anti-reflective properties: The total reflectance of the nano inverted pyramids fabricated by our method can be as low as 12% without any anti-reflective layers, and down to only 0.33% with a silicon nitride coating. The results from angle resolved scattering measurements indicate that the existence of triple reflections is responsible for the reduced reflectance. The surfaces with the nano inverted pyramids also exhibit a distinct milky white color. PMID:27725703

[Fast determination of induction period of motor gasoline using Fourier transform attenuated total reflection infrared spectroscopy].

PubMed

Liu, Ya-Fei; Yuan, Hong-Fu; Song, Chun-Feng; Xie, Jin-Chun; Li, Xiao-Yu; Yan, De-Lin

2014-11-01

A new method is proposed for the fast determination of the induction period of gasoline using Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR). A dedicated analysis system with the function of spectral measurement, data processing, display and storage was designed and integrated using a Fourier transform infrared spectrometer module and chemometric software. The sample presentation accessory designed which has advantages of constant optical path, convenient sample injection and cleaning is composed of a nine times reflection attenuated total reflectance (ATR) crystal of zinc selenide (ZnSe) coated with a diamond film and a stainless steel lid with sealing device. The influence of spectral scanning number and repeated sample loading times on the spectral signal-to-noise ratio was studied. The optimum spectral scanning number is 15 times and the optimum sample loading number is 4 times. Sixty four different gasoline samples were collected from the Beijing-Tianjin area and the induction period values were determined as reference data by standard method GB/T 8018-87. The infrared spectra of these samples were collected in the operating condition mentioned above using the dedicated fast analysis system. Spectra were pretreated using mean centering and 1st derivative to reduce the influence of spectral noise and baseline shift A PLS calibration model for the induction period was established by correlating the known induction period values of the samples with their spectra. The correlation coefficient (R2), standard error of calibration (SEC) and standard error of prediction (SEP) of the model are 0.897, 68.3 and 91.9 minutes, respectively. The relative deviation of the model for gasoline induction period prediction is less than 5%, which meets the requirements of repeatability tolerance in GB method. The new method is simple and fast. It takes no more than 3 minutes to detect one sample. Therefore, the method is feasible for implementing fast determination of gasoline induction period, and of a positive meaning in the evaluation of fuel quality.

Chemometric analysis of attenuated total reflectance infrared spectra of Proteus mirabilis strains with defined structures of LPS.

PubMed

Zarnowiec, Paulina; Mizera, Andrzej; Chrapek, Magdalena; Urbaniak, Mariusz; Kaca, Wieslaw

2016-07-01

Proteus spp. strains are some of the most important pathogens associated with complicated urinary tract infections and bacteremia affecting patients with immunodeficiency and long-term urinary catheterization. For epidemiological purposes, various molecular typing methods have been developed for this pathogen. However, these methods are labor intensive and time consuming. We evaluated a new method of differentiation between strains. A collection of Proteus spp. strains was analyzed by attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy in the mid-infrared region. ATR FT-IR spectroscopy used in conjunction with a diamond ATR accessory directly produced the biochemical profile of the surface chemistry of bacteria. We conclude that a combination of ATR FT-IR spectroscopy and mathematical modeling provides a fast and reliable alternative for discrimination between Proteus isolates, contributing to epidemiological research. © The Author(s) 2016.

Total Internal Reflection Microscopy (TIRM) as a nondestructive surface damage assessment tool

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

Liao, Z.M.; Cohen, S.J.; Taylor, J.R.

1994-10-01

An easy to use, nondestructive, method for evaluating subsurface damage in polished substrates has been established at LLNL. Subsurface damage has been related to laser damage in coated optical components used in high power, high repetition rate laser systems. Total Internal Reflection Microscopy (TIRM) has been shown to be a viable nondestructive technique in analyzing subsurface damage in optical components. A successful TIRM system has been established for evaluating subsurface damage on fused silica components. Laser light scattering from subsurface damage sites is collected through a Nomarski microscope. These images are then captured by a CCD camera for analysis onmore » a computer. A variety of optics, including components with intentional subsurface damage due to grinding and polishing, have been analyzed and their TIRM images compared to an existing destructive etching method. Methods for quantitative measurement of subsurface damage are also discussed.« less

Determining the Size of Pores in a Partially Transparent Ceramics from Total-Reflection Spectra

NASA Astrophysics Data System (ADS)

Mironov, R. A.; Zabezhailov, M. O.; Georgiu, I. F.; Cherepanov, V. V.; Rusin, M. Yu.

2018-03-01

A technique is proposed for determining the pore-size distribution based on measuring the dependence of total reflectance in the domain of partial transparency of a material. An assumption about equality of scattering-coefficient spectra determined by solving the inverse radiation transfer problem and by theoretical calculation with the Mie theory is used. The technique is applied to studying a quartz ceramics. The poresize distribution is also determined using mercury and gas porosimetry. All three methods are shown to produce close results for pores with diameters of <180 nm, which occupy 90% of the void volume. In the domain of pore dimensions of >180 nm, the methods show differences that might be related to both specific procedural features and the structural properties of ceramics. The spectral-scattering method has a number of advantages over traditional porosimetry, and it can be viewed as a routine industrial technique.

Registration of T-2 mycotoxin with total internal reflection ellipsometry and QCM impedance methods.

PubMed

Nabok, A V; Tsargorodskaya, A; Holloway, A; Starodub, N F; Gojster, O

2007-01-15

A sensitive optical method of total internal reflection ellipsometry (TIRE) in conjunction with immune assay approach was exploited for the registration of T-2 mycotoxin in a wide range of concentrations from 100 microg/ml down to 0.15 ng/ml. Association constants of 1.4x10(6) and 1.9x10(7)mol(-1)s for poly- and monoclonal T-2 antibodies, respectively, were evaluated from TIRE kinetic measurements. According to TIRE data fitting, binding of T-2 molecules to antibodies (at saturation) has resulted in the increase in adsorbed layer thickness of 4-5 nm. The QCM impedance measurements data showed anomalously large mass increase and film softening, most likely, due to the binding of large T-2 aggregates to antibodies.

STANDARDIZED ASSESSMENT METHOD (SAM) FOR RIVERINE MACROINVERTEBRATES

EPA Science Inventory

During the summer of 2001, twelve sites were sampled for macroinvertebrates, six each on the Great Miami and Kentucky Rivers. Sites were chosen in each river from those sampled in the 1999 methods comparison study to reflect a disturbance gradient. At each site, a total distanc...

Superresolution confocal technology for displacement measurements based on total internal reflection.

PubMed

Kuang, Cuifang; Ali, M Yakut; Hao, Xiang; Wang, Tingting; Liu, Xu

2010-10-01

In order to achieve a higher axial resolution for displacement measurement, a novel method is proposed based on total internal reflection filter and confocal microscope principle. A theoretical analysis of the basic measurement principles is presented. The analysis reveals that the proposed confocal detection scheme is effective in enhancing the resolution of nonlinearity of the reflectance curve greatly. In addition, a simple prototype system has been developed based on the theoretical analysis and a series of experiments have been performed under laboratory conditions to verify the system feasibility, accuracy, and stability. The experimental results demonstrate that the axial resolution in displacement measurements is better than 1 nm in a range of 200 nm which is threefold better than that can be achieved using the plane reflector.

Design and analysis of non-polarizing beam splitter in a glass cube

NASA Astrophysics Data System (ADS)

Shi, Jinhui; Wang, Zhengping; Huang, Zongjun; Li, Qingbo

2008-11-01

The reflectance and transmittance of thin films at oblique incident angles exhibit strong polarization effects, particularly for the films inside a glass cube. However, the polarization effects are undesirable in many applications. To solve this problem, non-polarizing beam splitters with unique optical thin films have been achieved employing a method of combination of interference and frustrated total internal reflection, the non-polarizing condition expressions based on frustrated total internal reflection has been derived, and the design examples of non-polarizing beam splitters with an optimization technique have been also presented. The results of Rp=(50+/-0.5)%, Rs=(50+/-0.5)% andΔr=(0+/-0.3) degree in the wavelength range of 400-700nm have been obtained. The thickness sensitivity of NPBSs is also analyzed.

Enface Thickness Mapping and Reflectance Imaging of Retinal Layers in Diabetic Retinopathy

PubMed Central

Francis, Andrew W.; Wanek, Justin; Lim, Jennifer I.; Shahidi, Mahnaz

2015-01-01

Purpose To present a method for image segmentation and generation of enface thickness maps and reflectance images of retinal layers in healthy and diabetic retinopathy (DR) subjects. Methods High density spectral domain optical coherence tomography (SDOCT) images were acquired in 10 healthy and 4 DR subjects. Customized image analysis software identified 5 retinal cell layer interfaces and generated thickness maps and reflectance images of the total retina (TR), inner retina (IR), outer retina (OR), and the inner segment ellipsoid (ISe) band. Thickness maps in DR subjects were compared to those of healthy subjects by generating deviation maps which displayed retinal locations with thickness below, within, and above the normal 95% confidence interval. Results In healthy subjects, TR and IR thickness maps displayed the foveal depression and increased thickness in the parafoveal region. OR and ISe thickness maps showed increased thickness at the fovea, consistent with normal retinal anatomy. In DR subjects, thickening and thinning in localized regions were demonstrated on TR, IR, OR, and ISe thickness maps, corresponding to retinal edema and atrophy, respectively. TR and OR reflectance images showed reduced reflectivity in regions of increased thickness. Hard exudates appeared as hyper-reflective spots in IR reflectance images and casted shadows on the deeper OR and ISe reflectance images. The ISe reflectance image clearly showed the presence of focal laser scars. Conclusions Enface thickness mapping and reflectance imaging of retinal layers is a potentially useful method for quantifying the spatial and axial extent of pathologies due to DR. PMID:26699878

Orientation and Rotational Motions of Single Molecules by Polarized Total Internal Reflection Fluorescence Microscopy (polTIRFM)

PubMed Central

Beausang, John F.; Sun, Yujie; Quinlan, Margot E.; Forkey, Joseph N.; Goldman, Yale E.

2013-01-01

In this article, we describe methods to detect the spatial orientation and rotational dynamics of single molecules using polarized total internal reflection fluorescence microscopy (polTIRFM). polTIRFM determines the three-dimensional angular orientation and the extent of wobble of a fluorescent probe bound to the macromolecule of interest. We discuss single-molecule versus ensemble measurements, as well as single-molecule techniques for orientation and rotation, and fluorescent probes for orientation studies. Using calmodulin (CaM) as an example of a target protein, we describe a method for labeling CaM with bifunctional rhodamine (BR). We also describe the physical principles and experimental setup of polTIRFM. We conclude with a brief introduction to assays using polTIRFM to assess the interaction of actin and myosin. PMID:22550303

Auto-calibrated scanning-angle prism-type total internal reflection microscopy for nanometer-precision axial position determination and optional variable-illumination-depth pseudo total internal reflection microscopy

DOEpatents

Fang, Ning; Sun, Wei

2015-04-21

A method, apparatus, and system for improved VA-TIRFM microscopy. The method comprises automatically controlled calibration of one or more laser sources by precise control of presentation of each laser relative a sample for small incremental changes of incident angle over a range of critical TIR angles. The calibration then allows precise scanning of the sample for any of those calibrated angles for higher and more accurate resolution, and better reconstruction of the scans for super resolution reconstruction of the sample. Optionally the system can be controlled for incident angles of the excitation laser at sub-critical angles for pseudo TIRFM. Optionally both above-critical angle and sub critical angle measurements can be accomplished with the same system.

Satellite estimation of incident photosynthetically active radiation using ultraviolet reflectance

NASA Technical Reports Server (NTRS)

Eck, Thomas F.; Dye, Dennis G.

1991-01-01

A new satellite remote sensing method for estimating the amount of photosynthetically active radiation (PAR, 400-700 nm) incident at the earth's surface is described and tested. Potential incident PAR for clear sky conditions is computed from an existing spectral model. A major advantage of the UV approach over existing visible band approaches to estimating insolation is the improved ability to discriminate clouds from high-albedo background surfaces. UV spectral reflectance data from the Total Ozone Mapping Spectrometer (TOMS) were used to test the approach for three climatically distinct, midlatitude locations. Estimates of monthly total incident PAR from the satellite technique differed from values computed from ground-based pyranometer measurements by less than 6 percent. This UV remote sensing method can be applied to estimate PAR insolation over ocean and land surfaces which are free of ice and snow.

Light polarization measurements - A method to determine the specular and diffuse light-scattering properties of both leaves and plant canopies

NASA Technical Reports Server (NTRS)

Vanderbilt, V. C.; Grant, L.

1984-01-01

The contributions of diffuse and specular reflection to the total canopy reflection of sunlight are determined experimentally for wheat at two stages of development using spectroradiometer measurements obtained at 13 wavelengths in the 480-720-nm range with a polarizing film in maximum and minimum signal-amplitude positions. The data and computation techniques are presented in tables, diagrams, and graphs, and the need to take specular reflection into account in constructing models of light/canopy interaction is stressed.

Nonpolarizing beam splitter designed by frustrated total internal reflection inside a glass cube.

PubMed

Xu, Xueke; Shao, Jianda; Fan, Zhengxiu

2006-06-20

A method for the design of an all-dielectric nonpolarizing prism beam splitter utilizing the principle of frustrated total internal reflection is reported. The nonpolarizing condition for a prism beam splitter is discussed, and some single layer design examples are elaborated. The concept can be applied to a wide range of wavelengths and arbitrary transmittance values, and with the help of a computer design program examples of 400-700 nm, T(p)=T(s)=0.5+/-0.01, with incident angles of 45 degrees and 62 degrees are given. In addition, the sensitivity and application of the design are also discussed.

Retrieval of optical properties of skin from measurement and modeling the diffuse reflectance

NASA Astrophysics Data System (ADS)

Douven, Lucien F. A.; Lucassen, Gerald W.

2000-06-01

We present results on the retrieval of skin optical properties obtained by fitting of measurements of the diffuse reflectance of human skin. Reflectance spectra are simulated using an analytical model based on the diffusion approximation. This model is implemented in a simplex fit routine. The skin optical model used consists of five layers representing epidermis, capillary blood plexus, dermis, deep blood plexus and hypodermis. The optical properties of each layer are assumed homogeneously distributed. The main optical absorbers included are melanin in epidermis and blood. The experimental setup consists of a HP photospectrometer equipped with a remote fiber head. Total reflectance spectra were measured in the 400 - 820 nm wavelength range on the volar underarm of 19 volunteers under various conditions influencing the blood content and oxygenation degree. Changes in the reflectance spectra were observed. Using the fit routine changes in blood content in the capillary blood plexus and in the deep blood plexus could be quantified. These showed different influences on the total reflectance. The method can be helpful to quantitatively assess changes in skin color appearance such as occurs in the treatment of port wine stains, blanching, skin irritation and tanning.

Refraction-reflection of electrons at lateral metallic interfaces

NASA Astrophysics Data System (ADS)

Kher-Elden, M. A.; El-Fattah, Z. M. Abd; Yassin, O.; El-Okr, M. M.

2017-11-01

Electron boundary element method (EBEM) has been employed to simulate electron refraction at the lateral interface between two homogenous metals featuring surface states characterized by isotropic constant energy surfaces. A decent agreement was achieved between the real-space EBEM simulations and the wave-space analysis obtained from electron plane wave expansion (EPWE) method. Calculations were performed for three different electron energies, being -0.05, -0.15, and -0.25 eV, where the reference energy is set to -0.4 eV, i.e., the band minimum of the Cu(111) surface state. For an interface separating two metals with the same effective mass (0.41 me) and a potential difference of 0.2 eV, we demonstrate that electrons with the first two energies exhibit refraction at the interface, following the Snell's law, and total internal reflections occur beyond energy-dependent critical angles, whereas for the third electron energy, a total internal reflection occurs at all incident angles. These findings were used to simulate optical elements such as convex lenses and possible guiding through perfect electron mirrors, in contrast to Bragg-based guiding. Given the varieties of possible means of manipulating the dispersion parameters via surface adsorbates and thin-film growth, the degree of electron refraction-reflection at metallic interfaces could be precisely tuned.

Nondestructive detection of total viable count changes of chilled pork in high oxygen storage condition based on hyperspectral technology

NASA Astrophysics Data System (ADS)

Zheng, Xiaochun; Peng, Yankun; Li, Yongyu; Chao, Kuanglin; Qin, Jianwei

2017-05-01

The plate count method is commonly used to detect the total viable count (TVC) of bacteria in pork, which is timeconsuming and destructive. It has also been used to study the changes of the TVC in pork under different storage conditions. In recent years, many scholars have explored the non-destructive methods on detecting TVC by using visible near infrared (VIS/NIR) technology and hyperspectral technology. The TVC in chilled pork was monitored under high oxygen condition in this study by using hyperspectral technology in order to evaluate the changes of total bacterial count during storage, and then evaluate advantages and disadvantages of the storage condition. The VIS/NIR hyperspectral images of samples stored in high oxygen condition was acquired by a hyperspectral system in range of 400 1100nm. The actual reference value of total bacteria was measured by standard plate count method, and the results were obtained in 48 hours. The reflection spectra of the samples are extracted and used for the establishment of prediction model for TVC. The spectral preprocessing methods of standard normal variate transformation (SNV), multiple scatter correction (MSC) and derivation was conducted to the original reflectance spectra of samples. Partial least squares regression (PLSR) of TVC was performed and optimized to be the prediction model. The results show that the near infrared hyperspectral technology based on 400-1100nm combined with PLSR model can describe the growth pattern of the total bacteria count of the chilled pork under the condition of high oxygen very vividly and rapidly. The results obtained in this study demonstrate that the nondestructive method of TVC based on NIR hyperspectral has great potential in monitoring of edible safety in processing and storage of meat.

Reformulation of Traditional Chamomile Oil: Quality Controls and Fingerprint Presentation Based on Cluster Analysis of Attenuated Total Reflectance-Infrared Spectral Data.

PubMed

Zargaran, Arman; Sakhteman, Amirhossein; Faridi, Pouya; Daneshamouz, Saeid; Akbarizadeh, Amin Reza; Borhani-Haghighi, Afshin; Mohagheghzadeh, Abdolali

2017-10-01

Herbal oils have been widely used in Iran as medicinal compounds dating back to thousands of years in Iran. Chamomile oil is widely used as an example of traditional oil. We remade chamomile oils and tried to modify it with current knowledge and facilities. Six types of oil (traditional and modified) were prepared. Microbial limit tests and physicochemical tests were performed on them. Also, principal component analysis, hierarchical cluster analysis, and partial least squares discriminant analysis were done on the spectral data of attenuated total reflectance-infrared in order to obtain insight based on classification pattern of the samples. The results show that we can use modified versions of the chamomile oils (modified Clevenger-type apparatus method and microwave method) with the same content of traditional ones and with less microbial contaminations and better physicochemical properties.

Development of optical coatings for 157-nm lithography. II. Reflectance, absorption, and scatter measurement

NASA Astrophysics Data System (ADS)

Otani, Minoru; Biro, Ryuji; Ouchi, Chidane; Hasegawa, Masanobu; Suzuki, Yasuyuki; Sone, Kazuho; Niisaka, Shunsuke; Saito, Tadahiko; Saito, Jun; Tanaka, Akira

2002-06-01

The total loss that can be suffered by an antireflection (AR) coating consists of reflectance loss, absorption loss, and scatter loss. To separate these losses we developed a calorimetric absorption measurement apparatus and an ellipsoidal Coblentz hemisphere based scatterometer for 157-nm optics. Reflectance, absorption, and scatter of AR coatings were measured with these apparatuses. The AR coating samples were supplied by Japanese vendors. Each AR coating as supplied was coated with the vendor's coating design by that vendor's coating process. Our measurement apparatuses, methods, and results for these AR coatings are presented here.

Determination of nutritional parameters of yoghurts by FT Raman spectroscopy

NASA Astrophysics Data System (ADS)

Czaja, Tomasz; Baranowska, Maria; Mazurek, Sylwester; Szostak, Roman

2018-05-01

FT-Raman quantitative analysis of nutritional parameters of yoghurts was performed with the help of partial least squares models. The relative standard errors of prediction for fat, lactose and protein determination in the quantified commercial samples equalled to 3.9, 3.2 and 3.6%, respectively. Models based on attenuated total reflectance spectra of the liquid yoghurt samples and of dried yoghurt films collected with the single reflection diamond accessory showed relative standard errors of prediction values of 1.6-5.0% and 2.7-5.2%, respectively, for the analysed components. Despite a relatively low signal-to-noise ratio in the obtained spectra, Raman spectroscopy, combined with chemometrics, constitutes a fast and powerful tool for macronutrients quantification in yoghurts. Errors received for attenuated total reflectance method were found to be relatively higher than those for Raman spectroscopy due to inhomogeneity of the analysed samples.

Airborne particulate matter (PM) filter analysis and modeling by total reflection X-ray fluorescence (TXRF) and X-ray standing wave (XSW).

PubMed

Borgese, L; Salmistraro, M; Gianoncelli, A; Zacco, A; Lucchini, R; Zimmerman, N; Pisani, L; Siviero, G; Depero, L E; Bontempi, E

2012-01-30

This work is presented as an improvement of a recently introduced method for airborne particulate matter (PM) filter analysis [1]. X-ray standing wave (XSW) and total reflection X-ray fluorescence (TXRF) were performed with a new dedicated laboratory instrumentation. The main advantage of performing both XSW and TXRF, is the possibility to distinguish the nature of the sample: if it is a small droplet dry residue, a thin film like or a bulk sample. Another advantage is related to the possibility to select the angle of total reflection to make TXRF measurements. Finally, the possibility to switch the X-ray source allows to measure with more accuracy lighter and heavier elements (with a change in X-ray anode, for example from Mo to Cu). The aim of the present study is to lay the theoretical foundation of the new proposed method for airborne PM filters quantitative analysis improving the accuracy and efficiency of quantification by means of an external standard. The theoretical model presented and discussed demonstrated that airborne PM filters can be considered as thin layers. A set of reference samples is prepared in laboratory and used to obtain a calibration curve. Our results demonstrate that the proposed method for quantitative analysis of air PM filters is affordable and reliable without the necessity to digest filters to obtain quantitative chemical analysis, and that the use of XSW improve the accuracy of TXRF analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

Analysis of elemental concentration censored distributions in breast malignant and breast benign neoplasm tissues

NASA Astrophysics Data System (ADS)

Kubala-Kukuś, A.; Banaś, D.; Braziewicz, J.; Góźdź, S.; Majewska, U.; Pajek, M.

2007-07-01

The total reflection X-ray fluorescence method was applied to study the trace element concentrations in human breast malignant and breast benign neoplasm tissues taken from the women who were patients of Holycross Cancer Centre in Kielce (Poland). These investigations were mainly focused on the development of new possibilities of cancer diagnosis and therapy monitoring. This systematic comparative study was based on relatively large (˜ 100) population studied, namely 26 samples of breast malignant and 68 samples of breast benign neoplasm tissues. The concentrations, being in the range from a few ppb to 0.1%, were determined for thirteen elements (from P to Pb). The results were carefully analysed to investigate the concentration distribution of trace elements in the studied samples. The measurements of concentration of trace elements by total reflection X-ray fluorescence were limited, however, by the detection limit of the method. It was observed that for more than 50% of elements determined, the concentrations were not measured in all samples. These incomplete measurements were treated within the statistical concept called left-random censoring and for the estimation of the mean value and median of censored concentration distributions, the Kaplan-Meier estimator was used. For comparison of concentrations in two populations, the log-rank test was applied, which allows to compare the censored total reflection X-ray fluorescence data. Found statistically significant differences are discussed in more details. It is noted that described data analysis procedures should be the standard tool to analyze the censored concentrations of trace elements analysed by X-ray fluorescence methods.

Chapter 7: Total internal reflection fluorescence microscopy.

PubMed

Axelrod, Daniel

2008-01-01

Total internal reflection fluorescence microscopy (TIRFM), also known as evanescent wave microscopy, is used in a wide range of applications, particularly to view single molecules attached to planar surfaces and to study the position and dynamics of molecules and organelles in living culture cells near the contact regions with the glass coverslip. TIRFM selectively illuminates fluorophores only in a very thin (less than 100 nm deep) layer near the substrate, thereby avoiding excitation of fluorophores outside this subresolution optical section. This chapter reviews the history, current applications in cell biology and biochemistry, basic optical theory, combinations with numerous other optical and spectroscopic approaches, and a range of setup methods, both commercial and custom.

Microplastics on sandy beaches of the Baja California Peninsula, Mexico.

PubMed

Piñon-Colin, Teresita de Jesus; Rodriguez-Jimenez, Ruben; Pastrana-Corral, Miguel Angel; Rogel-Hernandez, Eduardo; Wakida, Fernando Toyohiko

2018-06-01

Microplastics have become a concern in recent years because of their negative impact on marine and freshwater environments. Twenty-one sandy beach sites were sampled to investigate the occurrence and distribution of microplastics on the sandy beaches of the Baja California Peninsula, Mexico, as well as their spectroscopic characterization and morphology. Microplastics were separated using the density method and identified using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR). The mean abundance of microplastics in the samples was 135 ± 92 particles kg−1, and fiber was the most abundant microplastic found in the samples, comprising 91% of the total microplastics identified. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis of the microplastics showed that the main polymers found in microplastics were polyacrylic, polyacrylamide, polyethylene terephthalate, polyesters, and nylon.

TRASER - Total Reflection Amplification of Spontaneous Emission of Radiation

PubMed Central

Zachary, Christopher B.; Gustavsson, Morgan

2012-01-01

Background and Objective Light and lasers in medical therapy have made dramatic strides since their invention five decades ago. However, the manufacture of lasers can be complex and expensive which often makes treatments limited and costly. Further, no single laser will provide the correct parameters to treat all things. Hence, laser specialists often need multiple devices to practice their specialty. A new concept is described herein that has the potential to replace many lasers and light sources with a single ‘tunable’ device. Study Design/Material and Methods This device amplifies spontaneous emission of radiation by capturing and retaining photons through total internal reflection, hence the acronym Total Reflection Amplification of Spontaneous Emission of Radiation, or TRASER. Results Specific peaks of light can be produced in a reproducible manner with high peak powers of variable pulse durations, a large spot size, and high repetition rate. Conclusion Considering the characteristics and parameters of Traser technology, it is possible that this one device would likely be able to replace the pulsed dye laser and many other light based systems. PMID:22558261

Using artistic-narrative to stimulate reflection on physician bias.

PubMed

Ross, Paula T; Lypson, Monica L

2014-01-01

Physician bias toward patients directly impacts patient care and health outcomes. However, too little research has been done investigating avenues to bring about self-awareness in this area to eliminate commonly held stereotypes that fuel physician bias. The purpose of this study was to explore the ways in which 2nd-year medical students' reflected on an artistic-narrative presentation given by a woman with sickle cell disease. A total of 320 2nd-year medical student essays were reviewed for content relevant to the artistic-narrative presentation. A total of 75 essays were identified and served as the data for this study. These 75 essays were analyzed using qualitative interpretive thematic content analysis to identify students' perceptions and reflections on culture in the healthcare environment and the patient-provider relationship. The analysis of the reflective essays revealed that this exercise helped students acknowledge physician bias in pain treatment, foster empathetic views toward patients as individuals, and recognize various ways in which biased beliefs can provide incite in healthcare disparities. These findings suggest that the combination of methods--art, narrative, and written reflection--helped students acknowledge their own bias as well as the ways in which taken-for-granted assumptions and biases can influence patient care.

A method for trace element determination of single Daphnia specimens using total reflection X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Mages, Margarete; Woelfl, Stefan; v. Tümpling jun, Wolf

2001-11-01

Two new preparation techniques for total-reflection X-ray fluorescence (TXRF) element determination of single freshwater crustacean specimens (dry weight: 3-40 μg ind -1) have been developed and tested using Daphnia pulex from a deep, oligotrophic freshwater lake located in southern Chile. Dry method: Specimens were washed with 0.2 μm filtered lake water and frozen in liquid nitrogen. The freeze-dried Daphnia specimens were weighed using an ultra-fine microbalance and placed on quartz glass carriers for TXRF analysis. Wet method: Specimens were washed with 0.2 μm filtered lake water and placed on quartz glass carriers for TXRF analysis and dried in air. The dry weight was determined using the previously established body length-dry weight relationship. Method validation for both the dry and the wet preparation method in combination with TXRF spectrometry for the element determination in small single freshwater crustaceans showed that both methods can be used for routine investigations. There were no significant differences between the dry and the wet methods concerning the elements Ca, K, Fe, Zn, Br, P, Cu, but the determination of Mn, S and Sr revealed significant differences between the two methods. It seems that the dry method yields more precise results, but the wet method is easier to handle in the field when samples cannot be fixed with liquid nitrogen.

Iterative discrete ordinates solution of the equation for surface-reflected radiance

NASA Astrophysics Data System (ADS)

Radkevich, Alexander

2017-11-01

This paper presents a new method of numerical solution of the integral equation for the radiance reflected from an anisotropic surface. The equation relates the radiance at the surface level with BRDF and solutions of the standard radiative transfer problems for a slab with no reflection on its surfaces. It is also shown that the kernel of the equation satisfies the condition of the existence of a unique solution and the convergence of the successive approximations to that solution. The developed method features two basic steps: discretization on a 2D quadrature, and solving the resulting system of algebraic equations with successive over-relaxation method based on the Gauss-Seidel iterative process. Presented numerical examples show good coincidence between the surface-reflected radiance obtained with DISORT and the proposed method. Analysis of contributions of the direct and diffuse (but not yet reflected) parts of the downward radiance to the total solution is performed. Together, they represent a very good initial guess for the iterative process. This fact ensures fast convergence. The numerical evidence is given that the fastest convergence occurs with the relaxation parameter of 1 (no relaxation). An integral equation for BRDF is derived as inversion of the original equation. The potential of this new equation for BRDF retrievals is analyzed. The approach is found not viable as the BRDF equation appears to be an ill-posed problem, and it requires knowledge the surface-reflected radiance on the entire domain of both Sun and viewing zenith angles.

Frustrated Total Internal Reflection: A Simple Application and Demonstration.

ERIC Educational Resources Information Center

Zanella, F. P.; Magalhaes, D. V.; Oliveira, M. M.; Bianchi, R. F.; Misoguti, L.; Mendonca, C. R.

2003-01-01

Describes the total internal reflection process that occurs when the internal angle of incidence is equal to or greater than the critical angle. Presents a demonstration of the effect of frustrated total internal reflection (FTIR). (YDS)

Nonimaging optics for nonuniform brightness distributions

NASA Astrophysics Data System (ADS)

Jenkins, David G.; Winston, Roland

1995-08-01

We present a general design method of nonimaging optics that obtains the highest possible concentration for a given absorber shape. This technique, which uses a complimentary edge ray to simplify the geometrical formulism, recovers familiar designs for flat phase space distributions, such as trumpets, and (theta) 1-(theta) 2 concentrators. This method is easy to use and handles diverse boundary conditions, such as reflection, satisfying total internal reflection or design within a material of graded index. Presented is a novel two-stage 2D solar collector with a fixed circular primary mirror and nonimaging secondary. This newly developed secondary gives a 25% improvement over conventional nonimaging concentrators.

Number of terms required in the Fourier expansion of the reflection function for optically thick atmospheres

NASA Technical Reports Server (NTRS)

King, M. D.

1983-01-01

Computational results are presented for the separate terms in the Fourier expansion of the phase function and the reflection function of a semiinfinite, conservatively scattering atmosphere composed of cloud particles. The calculations involve successive applications of invariant imbedding, doubling, and asymptotic fitting methods to cover the range from very thin to very thick atmospheres. From the results, the ratio of the total reflection function to the first-order reflection function is determined as well as the number of terms required to describe the reflection function to an accuracy of 0.1 percent. The number of terms required depends strongly on the zenith angles of incidence and reflection as well as on details of the phase function. These results are compared with similar results obtained for a Henyey-Greenstein phase function having the same asymmetry factor as in the cloud model.

Application of multibounce attenuated total reflectance fourier transform infrared spectroscopy and chemometrics for determination of aspartame in soft drinks.

PubMed

Khurana, Harpreet Kaur; Cho, Il Kyu; Shim, Jae Yong; Li, Qing X; Jun, Soojin

2008-02-13

Aspartame is a low-calorie sweetener commonly used in soft drinks; however, the maximum usage dose is limited by the U.S. Food and Drug Administration. Fourier transform infrared (FTIR) spectroscopy with attenuated total reflectance sampling accessory and partial least-squares regression (PLS) was used for rapid determination of aspartame in soft drinks. On the basis of spectral characterization, the highest R2 value, and lowest PRESS value, the spectral region between 1600 and 1900 cm(-1) was selected for quantitative estimation of aspartame. The potential of FTIR spectroscopy for aspartame quantification was examined and validated by the conventional HPLC method. Using the FTIR method, aspartame contents in four selected carbonated diet soft drinks were found to average from 0.43 to 0.50 mg/mL with prediction errors ranging from 2.4 to 5.7% when compared with HPLC measurements. The developed method also showed a high degree of accuracy because real samples were used for calibration, thus minimizing potential interference errors. The FTIR method developed can be suitably used for routine quality control analysis of aspartame in the beverage-manufacturing sector.

LED-based interference-reflection microscopy combined with optical tweezers for quantitative three-dimensional microtubule imaging.

PubMed

Simmert, Steve; Abdosamadi, Mohammad Kazem; Hermsdorf, Gero; Schäffer, Erik

2018-05-28

Optical tweezers combined with various microscopy techniques are a versatile tool for single-molecule force spectroscopy. However, some combinations may compromise measurements. Here, we combined optical tweezers with total-internal-reflection-fluorescence (TIRF) and interference-reflection microscopy (IRM). Using a light-emitting diode (LED) for IRM illumination, we show that single microtubules can be imaged with high contrast. Furthermore, we converted the IRM interference pattern of an upward bent microtubule to its three-dimensional (3D) profile calibrated against the optical tweezers and evanescent TIRF field. In general, LED-based IRM is a powerful method for high-contrast 3D microscopy.

Effect of reflection and refraction on NEXAFS spectra measured in TEY mode

PubMed Central

2018-01-01

The evolution of near-edge X-ray absorption fine structure in the vicinity of the K-absorption edge of oxygen for HfO2 over a wide range of incidence angles is analyzed by simultaneous implementation of the total-electron-yield (TEY) method and X-ray reflection spectroscopy. It is established that the effect of refraction on the TEY spectrum is greater than that of reflection and extends into the angular region up to angles 2θc. Within angles that are less than the critical angle, both the reflection and refraction strongly distort the shape of the TEY spectrum. Limitations of the technique for the calculation of optical constants from the reflection spectra using the Kramers–Kronig relation in the limited energy region in the vicinity of thresholds are discussed in detail. PMID:29271772

Enface Thickness Mapping and Reflectance Imaging of Retinal Layers in Diabetic Retinopathy.

PubMed

Francis, Andrew W; Wanek, Justin; Lim, Jennifer I; Shahidi, Mahnaz

2015-01-01

To present a method for image segmentation and generation of enface thickness maps and reflectance images of retinal layers in healthy and diabetic retinopathy (DR) subjects. High density spectral domain optical coherence tomography (SDOCT) images were acquired in 10 healthy and 4 DR subjects. Customized image analysis software identified 5 retinal cell layer interfaces and generated thickness maps and reflectance images of the total retina (TR), inner retina (IR), outer retina (OR), and the inner segment ellipsoid (ISe) band. Thickness maps in DR subjects were compared to those of healthy subjects by generating deviation maps which displayed retinal locations with thickness below, within, and above the normal 95% confidence interval. In healthy subjects, TR and IR thickness maps displayed the foveal depression and increased thickness in the parafoveal region. OR and ISe thickness maps showed increased thickness at the fovea, consistent with normal retinal anatomy. In DR subjects, thickening and thinning in localized regions were demonstrated on TR, IR, OR, and ISe thickness maps, corresponding to retinal edema and atrophy, respectively. TR and OR reflectance images showed reduced reflectivity in regions of increased thickness. Hard exudates appeared as hyper-reflective spots in IR reflectance images and casted shadows on the deeper OR and ISe reflectance images. The ISe reflectance image clearly showed the presence of focal laser scars. Enface thickness mapping and reflectance imaging of retinal layers is a potentially useful method for quantifying the spatial and axial extent of pathologies due to DR.

Prisms with total internal reflection as solar reflectors

DOEpatents

Rabl, Arnulf; Rabl, Veronika

1978-01-01

An improved reflective wall for radiant energy collection and concentration devices is provided. The wall is comprised of a plurality of prisms whose frontal faces are adjacent and which reflect the desired radiation by total internal reflection.

Satellite-Sensor Calibration Verification Using the Cloud-Shadow Method

NASA Technical Reports Server (NTRS)

Reinersman, P.; Carder, K. L.; Chen, F. R.

1995-01-01

An atmospheric-correction method which uses cloud-shaded pixels together with pixels in a neighboring region of similar optical properties is described. This cloud-shadow method uses the difference between the total radiance values observed at the sensor for these two regions, thus removing the nearly identical atmospheric radiance contributions to the two signals (e.g. path radiance and Fresnel-reflected skylight). What remains is largely due to solar photons backscattered from beneath the sea to dominate the residual signal. Normalization by the direct solar irradiance reaching the sea surface and correction for some second-order effects provides the remote-sensing reflectance of the ocean at the location of the neighbor region, providing a known 'ground target' spectrum for use in testing the calibration of the sensor. A similar approach may be useful for land targets if horizontal homogeneity of scene reflectance exists about the shadow. Monte Carlo calculations have been used to correct for adjacency effects and to estimate the differences in the skylight reaching the shadowed and neighbor pixels.

Optical Reflectance and Fluorescence for Detecting Nitrogen Needs in Zea mays L.

NASA Technical Reports Server (NTRS)

McMurtrey, J. E.; Middleton, E. M.; Corp. L. A.; Campbell, P. K. Entcheva; Butcher, L. M.; Daughtry, C. S. T.

2003-01-01

Nitrogen (N) status in field grown corn (Zea mays L.) was assessed using spectral techniques. Passive reflectance remote sensing and, both passive and active fluorescence sensing methods were investigated. Reflectance and fluorescence methods are reported to detect changes in the primary plant pigments (chlorophylls a and b; carotenoids) in higher plant species. As a general rule, foliar chlorophyll a (Chl a) and chlorophyll b (Chl b) usually exist in approx.3:l ratio. In plants under stress, Chl b content is affected before Chl a reductions occur. For reflectance, a version of the chlorophyll absorption in reflectance index (CARI) method was tested with narrow bands from the Airborne Imaging Spectroradiometer for Applications (ASIA). CARI minimizes the effects of soil background on the signal from green canopies. A modified CARI (MCARI) was used to track total Chl a levels in the red dip of the spectrum from the corn canopy. A second MCARI was used to track the auxiliary plant pigments (Chl b and the carotenoids) in the yellow/orange/red edge part of the reflectance spectrum. The difference between these two MCARI indices detected variations in N levels across the field plot canopies using ASIA data. At the leaf level, ratios of fluorescence emissions in the blue, green, red and far-red wavelengths sensed responses that were associated with the plant pigments, and were indicative of energy transfer in the photosynthetic process. N stressed corn stands could be distinguish from those with optimally applied N with fluorescence emission spectra obtained from individual corn leaves. Both reflectance and fluorescence methods are sensitive in detecting corn N needs and may be especially powerful in monitoring crop conditions if both types of information can be combined.

Spectral distribution of solar radiation

NASA Technical Reports Server (NTRS)

Mecherikunnel, A. T.; Richmond, J.

1980-01-01

Available quantitative data on solar total and spectral irradiance are examined in the context of utilization of solar irradiance for terrestrial applications of solar energy. The extraterrestrial solar total and spectral irradiance values are also reviewed. Computed values of solar spectral irradiance at ground level for different air mass values and various levels of atmospheric pollution or turbidity are presented. Wavelengths are given for computation of solar, absorptance, transmittance and reflectance by the 100 selected-ordinate method and by the 50 selected-ordinate method for air mass 1.5 and 2 solar spectral irradiance for the four levels of atmospheric pollution.

ASSESSMENT OF LARGE RIVER BENTHIC MACROINVERTEBRATE ASSEMBLAGES

EPA Science Inventory

During the summer of 2001, twelve sites were sampled for macroinvertebrates, six each on the Great Miami and Kentucky Rivers. Sites were chosen in each river from those sampled in the 1999 methods comparison study to reflect a disturbance gradient. At each site, a total distanc...

ASSESSMENT OF LARGE RIVER MACROINVERTEBRATE ASSEMBLAGES

EPA Science Inventory

During the summer of 2001, twelve sites were sampled for macroinvertebrates, six each on the Great Miami and Kentucky Rivers. Sites were chosen in each river from those sampled in the 1999 methods comparison study to reflect a disturbance gradient. At each site, a total distanc...

Sensing cocaine in saliva with attenuated total reflection infrared (ATR-IR) spectroscopy combined with a one-step extraction method

NASA Astrophysics Data System (ADS)

Hans, Kerstin M.-C.; Gianella, Michele; Sigrist, Markus W.

2012-03-01

On-site drug tests have gained importance, e.g., for protecting the society from impaired drivers. Since today's drug tests are majorly only positive/negative, there is a great need for a reliable, portable and preferentially quantitative drug test. In the project IrSens we aim to bridge this gap with the development of an optical sensor platform based on infrared spectroscopy and focus on cocaine detection in saliva. We combine a one-step extraction method, a sample drying technique and infrared attenuated total reflection (ATR) spectroscopy. As a first step we have developed an extraction technique that allows us to extract cocaine from saliva to an almost infrared-transparent solvent and to record ATR spectra with a commercially available Fourier Transform-infrared spectrometer. To the best of our knowledge this is the first time that such a simple and easy-to-use one-step extraction method is used to transfer cocaine from saliva into an organic solvent and detect it quantitatively. With this new method we are able to reach a current limit of detection around 10 μg/ml. This new extraction method could also be applied to waste water monitoring and controlling caffeine content in beverages.

Hyperspectral Analysis of Soil Total Nitrogen in Subsided Land Using the Local Correlation Maximization-Complementary Superiority (LCMCS) Method.

PubMed

Lin, Lixin; Wang, Yunjia; Teng, Jiyao; Xi, Xiuxiu

2015-07-23

The measurement of soil total nitrogen (TN) by hyperspectral remote sensing provides an important tool for soil restoration programs in areas with subsided land caused by the extraction of natural resources. This study used the local correlation maximization-complementary superiority method (LCMCS) to establish TN prediction models by considering the relationship between spectral reflectance (measured by an ASD FieldSpec 3 spectroradiometer) and TN based on spectral reflectance curves of soil samples collected from subsided land which is determined by synthetic aperture radar interferometry (InSAR) technology. Based on the 1655 selected effective bands of the optimal spectrum (OSP) of the first derivate differential of reciprocal logarithm ([log{1/R}]'), (correlation coefficients, p < 0.01), the optimal model of LCMCS method was obtained to determine the final model, which produced lower prediction errors (root mean square error of validation [RMSEV] = 0.89, mean relative error of validation [MREV] = 5.93%) when compared with models built by the local correlation maximization (LCM), complementary superiority (CS) and partial least squares regression (PLS) methods. The predictive effect of LCMCS model was optional in Cangzhou, Renqiu and Fengfeng District. Results indicate that the LCMCS method has great potential to monitor TN in subsided lands caused by the extraction of natural resources including groundwater, oil and coal.

Portable total reflection x-ray fluorescence analysis in the identification of unknown laboratory hazards

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

Liu, Ying, E-mail: liu.ying.48r@st.kyoto-u.ac.jp; Imashuku, Susumu; Sasaki, Nobuharu

In this study, a portable total reflection x-ray fluorescence (TXRF) spectrometer was used to analyze unknown laboratory hazards that precipitated on exterior surfaces of cooling pipes and fume hood pipes in chemical laboratories. With the aim to examine the accuracy of TXRF analysis for the determination of elemental composition, analytical results were compared with those of wavelength-dispersive x-ray fluorescence spectrometry, scanning electron microscope and energy-dispersive x-ray spectrometry, energy-dispersive x-ray fluorescence spectrometry, inductively coupled plasma atomic emission spectrometry, x-ray diffraction spectrometry (XRD), and x-ray photoelectron spectroscopy (XPS). Detailed comparison of data confirmed that the TXRF method itself was not sufficient tomore » determine all the elements (Z > 11) contained in the samples. In addition, results suggest that XRD should be combined with XPS in order to accurately determine compound composition. This study demonstrates that at least two analytical methods should be used in order to analyze the composition of unknown real samples.« less

Enhanced sensitivity to dielectric function and thickness of absorbing thin films by combining total internal reflection ellipsometry with standard ellipsometry and reflectometry

NASA Astrophysics Data System (ADS)

Lizana, A.; Foldyna, M.; Stchakovsky, M.; Georges, B.; Nicolas, D.; Garcia-Caurel, E.

2013-03-01

High sensitivity of spectroscopic ellipsometry and reflectometry for the characterization of thin films can strongly decrease when layers, typically metals, absorb a significant fraction of the light. In this paper, we propose a solution to overcome this drawback using total internal reflection ellipsometry (TIRE) and exciting a surface longitudinal wave: a plasmon-polariton. As in the attenuated total reflectance technique, TIRE exploits a minimum in the intensity of reflected transversal magnetic (TM) polarized light and enhances the sensitivity of standard methods to thicknesses of absorbing films. Samples under study were stacks of three films, ZnO : Al/Ag/ZnO : Al, deposited on glass substrates. The thickness of the silver layer varied from sample to sample. We performed measurements with a UV-visible phase-modulated ellipsometer, an IR Mueller ellipsometer and a UV-NIR reflectometer. We used the variance-covariance formalism to evaluate the sensitivity of the ellipsometric data to different parameters of the optical model. Results have shown that using TIRE doubled the sensitivity to the silver layer thickness when compared with the standard ellipsometry. Moreover, the thickness of the ZnO : Al layer below the silver layer can be reliably quantified, unlike for the fit of the standard ellipsometry data, which is limited by the absorption of the silver layer.

Analysis of total and dissolved heavy metals in surface water of a Mexican polluted river by total reflection X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Zarazua, G.; Ávila-Pérez, P.; Tejeda, S.; Barcelo-Quintal, I.; Martínez, T.

2006-11-01

The present area of study is located in the Upper Course of the Lerma River (UCLR). The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The aim of the present study is to determine the heavy metal concentration of Cr, Mn, Fe, Cu and Pb in dissolved and total phases of the UCLR by means of Total Reflection X-ray Fluorescence Spectrometry (TXRF). The surface water samples were collected at 8 sites distributed following the stream flow direction of the river. Four sampling campaigns were carried out in each site in a 1-year period. A sample preparation method was applied in order to obtain the total and dissolved fraction and to destroy the organic matter. The total heavy metal average concentration decrease in the following order: Fe (2566 μg/L) > Mn (300 μg/L) > Cu (66 μg/L) > Cr (21 μg/L) > Pb (15 μg/L). In general, the heavy metal concentrations in water of the UCLR are below the maximum permissible limits.

Refractive Index Imaging of Cells with Variable-Angle Near-Total Internal Reflection (TIR) Microscopy.

PubMed

Bohannon, Kevin P; Holz, Ronald W; Axelrod, Daniel

2017-10-01

The refractive index in the interior of single cells affects the evanescent field depth in quantitative studies using total internal reflection (TIR) fluorescence, but often that index is not well known. We here present method to measure and spatially map the absolute index of refraction in a microscopic sample, by imaging a collimated light beam reflected from the substrate/buffer/cell interference at variable angles of incidence. Above the TIR critical angle (which is a strong function of refractive index), the reflection is 100%, but in the immediate sub-critical angle zone, the reflection intensity is a very strong ascending function of incidence angle. By analyzing the angular position of that edge at each location in the field of view, the local refractive index can be estimated. In addition, by analyzing the steepness of the edge, the distance-to-substrate can be determined. We apply the technique to liquid calibration samples, silica beads, cultured Chinese hamster ovary cells, and primary culture chromaffin cells. The optical technique suffers from decremented lateral resolution, scattering, and interference artifacts. However, it still provides reasonable results for both refractive index (~1.38) and for distance-to-substrate (~150 nm) for the cells, as well as a lateral resolution to about 1 µm.

Scope of Nursing Care in Polish Intensive Care Units

PubMed Central

Wysokiński, Mariusz; Ksykiewicz-Dorota, Anna; Fidecki, Wiesław

2013-01-01

Introduction. The TISS-28 scale, which may be used for nursing staff scheduling in ICU, does not reflect the complete scope of nursing resulting from varied cultural and organizational conditions of individual systems of health care. Aim. The objective of the study was an attempt to provide an answer to the question what scope of nursing care provided by Polish nurses in ICU does the TISS-28 scale reflect? Material and Methods. The methods of working time measurement were used in the study. For the needs of the study, 252 hours of continuous observation (day-long observation) and 3.697 time-schedule measurements were carried out. Results. The total nursing time was 4125.79 min. (68.76 hours), that is, 60.15% of the total working time of Polish nurses during the period analyzed. Based on the median test, the difference was observed on the level of χ 2 = 16945.8,P < 0.001 between the nurses' workload resulting from performance of activities qualified into the TISS-28 scale and load resulting from performance of interventions within the scopes of care not considered in this scale in Polish ICUs. Conclusions. The original version of the TISS-28 scale does not fully reflect the workload among Polish nurses employed in ICUs. PMID:24490162

Analysis of thin-film polymers using attenuated total internal reflection-Raman microspectroscopy.

PubMed

Tran, Willie; Tisinger, Louis G; Lavalle, Luis E; Sommer, André J

2015-01-01

Two methods commonly employed for molecular surface analysis and thin-film analysis of microscopic areas are attenuated total reflection infrared (ATR-IR) microspectroscopy and confocal Raman microspectroscopy. In the former method, the depth of the evanescent probe beam can be controlled by the wavelength of light, the angle of incidence, or the refractive index of the internal reflection element. Because the penetration depth is proportional to the wavelength of light, one could interrogate a smaller film thickness by moving from the mid-infrared region to the visible region employing Raman spectroscopy. The investigation of ATR Raman microspectroscopy, a largely unexplored technique available to Raman microspectroscopy, was carried out. A Renishaw inVia Raman microscope was externally modified and used in conjunction with a solid immersion lens (SIL) to perform ATR Raman experiments. Thin-film polymer samples were analyzed to explore the theoretical sampling depth for experiments conducted without the SIL, with the SIL, and with the SIL using evanescent excitation. The feasibility of micro-ATR Raman was examined by collecting ATR spectra from films whose thickness measured from 200 to 60 nm. Films of these thicknesses were present on a much thicker substrate, and features from the underlying substrate did not become visible until the thin film reached a thickness of 68 nm.

Nonintrusive measurement of the liquid refractive index by using properties of the cuvette wall.

PubMed

Xu, Ming; Ren, Junpeng; Miao, Runcai; Zhang, Zongquan

2016-10-01

We present a method of nonintrusive measurement of the refractive index of a liquid in a glass cuvette, which uses some optical properties of the cuvette wall and the principle of total internal reflection. By coating a transmission-scattering paint layer on the outer surface of the cuvette, we transform an incident laser beam into a transmitted scattered light. When the transmitted scattered light reaches the interface between the container wall and the liquid inside, the light beams satisfying the condition of total internal reflection are reflected to the coating layer, automatically forming a circular dark pattern that is related to the refractive index of the liquid. Based on an analytic relation between the diameter of the circular dark pattern and the refractive index of the liquid, we devised a method of in situ nonintrusive refractive index measurement. We tested the effect of several parameters on the measuring accuracy and found that the optimal thickness of the transmission-scattering layer is in the range of 50-70 μm, and the aperture of the diaphragm should be in the range of 0.7-1.0 mm. We measured the refractive indices of ethanol, Coca Cola, and red wine, and achieved an accuracy of ±3×10^-4  RIU (refractive index unit).

Monlithic nonplanar ring oscillator and method

NASA Technical Reports Server (NTRS)

Nilsson, Alan C. (Inventor); Byer, Robert L. (Inventor)

1991-01-01

A monolithic nonplanar ring oscillator having an optically isotropic solid-state laser body for propagating laser radiation about a nonplanar ring path internal to the laser body is disclosed. The monolithic laser body is configured to produce a 2N reflection nonplanar ring light path, where N is an integer greater than or equal to 2, comprising 2N-1 total internal reflections and one reflection at a coupler in a single round trip. Undirectional traveling wave oscillation of the laser is induced by the geometry of the nonplanar ring path together with the effect of an applied magnetic field and partial polarizer characteristics of the oblique reflection from the coupler. The 6-reflection nonplanar ring oscillator makes possible otpimal unidirectional oscillation (low loss for the oscillating direction of propagation and, simultaneously high loss for the nonoscillating direction of propagation) in monolithic NPROs using materials with index of refraction smaller than the square root of 3, for example, laser glass.

Use of Reflection-in-Action and Self-Assessment to Promote Critical Thinking Among Pharmacy Students

PubMed Central

Gregory, Paul AM; Chiu, Stephanie

2008-01-01

Objective To examine whether self-assessment and reflection-in-action improves critical thinking among pharmacy students. Methods A 24-item standardized test of critical thinking was developed utilizing previously-validated questions. Participants were divided into 2 groups (conditions). Those in condition 1 completed the test with no interference; those in condition 2 completed the test but were prompted at specific points during the test to reflect and self-assess. Results A total of 94 undergraduate (BScPhm) pharmacy students participated in this study. Significant differences (p < 0.05) were observed between those who completed the test under condition 1 and condition 2, suggesting reflection and self-assessment may contribute positively to improvement in critical thinking. Conclusions Structured opportunities to reflect-in-action and self-assess may be associated with improvements among pharmacy students in performance of tasks related to critical thinking. PMID:18698383

Developing a Value Framework: The Need to Reflect the Opportunity Costs of Funding Decisions.

PubMed

Sculpher, Mark; Claxton, Karl; Pearson, Steven D

2017-02-01

A growing number of health care systems internationally use formal economic evaluation methods to support health care funding decisions. Recently, a range of organizations have been advocating forms of analysis that have been termed "value frameworks." There has also been a push for analytical methods to reflect a fuller range of benefits of interventions through multicriteria decision analysis. A key principle that is invariably neglected in current and proposed frameworks is the need to reflect evidence on the opportunity costs that health systems face when making funding decisions. The mechanisms by which opportunity costs are realized vary depending on the system's financial arrangements, but they always mean that a decision to fund a specific intervention for a particular patient group has the potential to impose costs on others in terms of forgone benefits. These opportunity costs are rarely explicitly reflected in analysis to support decisions, but recent developments to quantify benefits forgone make more appropriate analyses feasible. Opportunity costs also need to be reflected in decisions if a broader range of attributes of benefit is considered, and opportunity costs are a key consideration in determining the appropriate level of total expenditure in a system. The principles by which opportunity costs can be reflected in analysis are illustrated in this article by using the example of the proposed methods for value-based pricing in the United Kingdom. Copyright © 2017 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Attenuated Total Reflectance Fourier transform infrared spectroscopy for determination of Long Chain Free Fatty Acid concentration in oily wastewater using the double wavenumber extrapolation technique.

PubMed

Hao, Zisu; Malyala, Divya; Dean, Lisa; Ducoste, Joel

2017-04-01

Long Chain Free Fatty Acids (LCFFAs) from the hydrolysis of fat, oil and grease (FOG) are major components in the formation of insoluble saponified solids known as FOG deposits that accumulate in sewer pipes and lead to sanitary sewer overflows (SSOs). A Double Wavenumber Extrapolative Technique (DWET) was developed to simultaneously measure LCFFAs and FOG concentrations in oily wastewater suspensions. This method is based on the analysis of the Attenuated Total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) spectrum, in which the absorbance of carboxyl bond (1710cm -1 ) and triglyceride bond (1745cm -1 ) were selected as the characteristic wavenumbers for total LCFFAs and FOG, respectively. A series of experiments using pure organic samples (Oleic acid/Palmitic acid in Canola oil) were performed that showed a linear relationship between the absorption at these two wavenumbers and the total LCFFA. In addition, the DWET method was validated using GC analyses, which displayed a high degree of agreement between the two methods for simulated oily wastewater suspensions (1-35% Oleic acid in Canola oil/Peanut oil). The average determination error of the DWET approach was ~5% when the LCFFA fraction was above 10wt%, indicating that the DWET could be applied as an experimental method for the determination of both LCFFAs and FOG concentrations in oily wastewater suspensions. Potential applications of this DWET approach includes: (1) monitoring the LCFFAs and FOG concentrations in grease interceptor (GI) effluents for regulatory compliance; (2) evaluating alternative LCFFAs/FOG removal technologies; and (3) quantifying potential FOG deposit high accumulation zones in the sewer collection system. Published by Elsevier B.V.

Cobalamin Concentrations in Fetal Liver Show Gender Differences: A Result from Using a High-Pressure Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry as an Ultratrace Cobalt Speciation Method.

PubMed

Bosle, Janine; Goetz, Sven; Raab, Andrea; Krupp, Eva M; Scheckel, Kirk G; Lombi, Enzo; Meharg, Andrew A; Fowler, Paul A; Feldmann, Jörg

2016-12-20

Maternal diet and lifestyle choices may affect placental transfer of cobalamin (Cbl) to the fetus. Fetal liver concentration of Cbl reflects nutritional status with regards to vitamin B12, but at these low concentration current Cbl measurement methods lack robustness. An analytical method based on enzymatic extraction with subsequent reversed-phase-high-pressure liquid chromatography (RP-HPLC) separation and parallel ICPMS and electrospray ionization (ESI)-Orbitrap-MS to determine specifically Cbl species in liver samples of only 10-50 mg was developed using 14 pig livers. Subsequently 55 human fetal livers were analyzed. HPLC-ICPMS analysis for cobalt (Co) and Cbl gave detection limits of 0.18 ng/g and 0.88 ng/g d.m. in liver samples, respectively, with a recovery of >95%. Total Co (Co t ) concentration did not reflect the amount of Cbl or vitamin B12 in the liver. Cbl bound Co contributes only 45 ± 15% to Co t . XRF mapping and μXANES analysis confirmed the occurrence of non-Cbl cobalt in pig liver hot spots indicating particular Co. No correlations of total cobalt nor Cbl with fetal weight or weeks of gestation were found for the human fetal livers. Although no gender difference could be identified for total Co concentration, female livers were significantly higher in Cbl concentration (24.1 ± 7.8 ng/g) than those from male fetuses (19.8 ± 7.1 ng/g) (p = 0.04). This HPLC-ICPMS method was able to quantify total Co t and Cbl in fetus liver, and it was sensitive and precise enough to identify this gender difference.

Determination of trace metals in spirits by total reflection X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Siviero, G.; Cinosi, A.; Monticelli, D.; Seralessandri, L.

2018-06-01

Eight spirituous samples were analyzed for trace metal content with Horizon Total Reflection X-Ray Fluorescence (TXRF) Spectrometer. The expected single metal amount is at the ng/g level in a mixed aqueous/organic matrix, thus requiring a sample preparation method capable of achieving suitable limits of detection. On-site enrichment and Atmospheric Pressure-Vapor Phase Decomposition allowed to detect Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr and Pb with detection limits ranging from 0.1 ng/g to 4.6 ng/g. These results highlight how the synergy between instrument and sample preparation strategy may foster the use of TXRF as a fast and reliable technique for the determination of trace elements in spirituous samples, either for quality control or risk assessment purposes.

Effect of anisotropy on defect mode peculiarities in chiral liquid crystals

NASA Astrophysics Data System (ADS)

Gevorgyan, A. H.; Oganesyan, K. B.

2018-01-01

The effect of anisotropy on defect mode peculiarities in cholesteric liquid crystals is investigated. The light transmission through the cholesteric liquid crystal layer with an anisotropic layer defect inside is solved by Ambartsumian’s layer addition modified method. Two cases are considered. In the first case, it is assumed that the defect layer is non-absorbing, and the effect of refraction anisotropy on the reflection, relative photonic density of states and the total field intensity produced in the defect layer are studied. In the second case, the defect layer is assumed to be isotropic for refraction and anisotropic for absorption, and the influence of defect layer absorption anisotropy on reflection, absorption, relative photonic density of states and the total field intensity produced in the defect layer are investigated.

The influence of transient change of total body water on relative body fats based on three bioelectrical impedance analyses methods. Comparison between before and after exercise with sweat loss, and after drinking.

PubMed

Demura, S; Yamaji, S; Goshi, F; Nagasawa, Y

2002-03-01

The purpose of this study was to clarify the influence of change of total body water caused by exercise and drinking, on relative body fat (%BF) based on three bioelectrical impedance analyses (BIA) methods, between hand and foot (H-F), between hand and hand (H-H), and between foot and foot (F-F). The subjects were 30 Japanese healthy young adults aged 18 to 23 years (15 males, 15 females). Measurements were made three times for each BIA method; before and after exercise with sweat, and after drinking, and also twice according to the under water weighing (UW) method, before exercise and after drinking. A pedaling exercise, with a bicycle ergometer, was used for 60 minutes as the exercise. The relationship of %BF between the UW method and each BIA method was mid-range or more (r=0.765-0.839). However, %BF based on the H-F and F-F BIA methods were higher than that based on the UW method. After drinking, %BF of all the BIA methods were higher than the UW method. %BF of the BIA methods after exercise indicated values lower than those before exercise. %BF of the H-F and H-H BIA methods after drinking were a little higher than those before exercise, indicating that those measurements reflect a slight change of body water. It was demonstrated that %BF of any BIA method reflect the change of body water caused by exercise, sweating, and drinking.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Polarisation splitting of laser beams by large angles with minimal reflection losses

NASA Astrophysics Data System (ADS)

Davydov, B. L.

2006-05-01

New crystal anisotropic prisms for splitting orthogonally polarised components of laser radiation by large angles with minimal reflection losses caused by the Brewster refraction and total internal reflection of polarised waves from the crystal—air interface are considered and the method for their calculation is described. It is shown that, by assembling glue-free combinations of two or three prisms, thermally stable beamsplitters can be fabricated, which are free from the beam astigmatism and the wave dispersion of the output angles of the beams. The parameters and properties of new beamsplitters are presented in a convenient form in figures and tables.

How to deal with missing longitudinal data in cost of illness analysis in Alzheimer's disease-suggestions from the GERAS observational study.

PubMed

Belger, Mark; Haro, Josep Maria; Reed, Catherine; Happich, Michael; Kahle-Wrobleski, Kristin; Argimon, Josep Maria; Bruno, Giuseppe; Dodel, Richard; Jones, Roy W; Vellas, Bruno; Wimo, Anders

2016-07-18

Missing data are a common problem in prospective studies with a long follow-up, and the volume, pattern and reasons for missing data may be relevant when estimating the cost of illness. We aimed to evaluate the effects of different methods for dealing with missing longitudinal cost data and for costing caregiver time on total societal costs in Alzheimer's disease (AD). GERAS is an 18-month observational study of costs associated with AD. Total societal costs included patient health and social care costs, and caregiver health and informal care costs. Missing data were classified as missing completely at random (MCAR), missing at random (MAR) or missing not at random (MNAR). Simulation datasets were generated from baseline data with 10-40 % missing total cost data for each missing data mechanism. Datasets were also simulated to reflect the missing cost data pattern at 18 months using MAR and MNAR assumptions. Naïve and multiple imputation (MI) methods were applied to each dataset and results compared with complete GERAS 18-month cost data. Opportunity and replacement cost approaches were used for caregiver time, which was costed with and without supervision included and with time for working caregivers only being costed. Total costs were available for 99.4 % of 1497 patients at baseline. For MCAR datasets, naïve methods performed as well as MI methods. For MAR, MI methods performed better than naïve methods. All imputation approaches were poor for MNAR data. For all approaches, percentage bias increased with missing data volume. For datasets reflecting 18-month patterns, a combination of imputation methods provided more accurate cost estimates (e.g. bias: -1 % vs -6 % for single MI method), although different approaches to costing caregiver time had a greater impact on estimated costs (29-43 % increase over base case estimate). Methods used to impute missing cost data in AD will impact on accuracy of cost estimates although varying approaches to costing informal caregiver time has the greatest impact on total costs. Tailoring imputation methods to the reason for missing data will further our understanding of the best analytical approach for studies involving cost outcomes.

ASSESSMENT OF LARGE RIVER MACROINVERTEBRATE ASSEMBLAGES: HOW FAR IS ENOUGH?

EPA Science Inventory

During the summer of 2001, twelve sites were sampled for macroinvertebrates, six each on the Great Miami and Kentucky Rivers. Sites were chosen in each river from those sampled in the 1999 methods comparison study to reflect a disturbance gradient. At each site, a total distanc...

Application of the Deming Management Method to Implement Total Quality Management in the DoD

DTIC Science & Technology

1991-09-01

of the authors and do not reflect the official policy or position of the Department of Defense or the U.S. Government. b T; Aocesslon For NTIS GRA&I...Plans should be made bhiat reflect the long-term well-being of a firm , not just the next quarterly report. Investments must.be made in the...world leaders. While this was happening U.S. firms continued ’ith their post WWII mindset. Industries in the U.S. must realize they can not survive

Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy as an Analytical Method to Investigate the Secondary Structure of a Model Protein Embedded in Solid Lipid Matrices.

PubMed

Zeeshan, Farrukh; Tabbassum, Misbah; Jorgensen, Lene; Medlicott, Natalie J

2018-02-01

Protein drugs may encounter conformational perturbations during the formulation processing of lipid-based solid dosage forms. In aqueous protein solutions, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy can investigate these conformational changes following the subtraction of spectral interference of solvent with protein amide I bands. However, in solid dosage forms, the possible spectral contribution of lipid carriers to protein amide I band may be an obstacle to determine conformational alterations. The objective of this study was to develop an ATR FT-IR spectroscopic method for the analysis of protein secondary structure embedded in solid lipid matrices. Bovine serum albumin (BSA) was chosen as a model protein, while Precirol AT05 (glycerol palmitostearate, melting point 58 ℃) was employed as the model lipid matrix. Bovine serum albumin was incorporated into lipid using physical mixing, melting and mixing, or wet granulation mixing methods. Attenuated total reflection FT-IR spectroscopy and size exclusion chromatography (SEC) were performed for the analysis of BSA secondary structure and its dissolution in aqueous media, respectively. The results showed significant interference of Precirol ATO5 with BSA amide I band which was subtracted up to 90% w/w lipid content to analyze BSA secondary structure. In addition, ATR FT-IR spectroscopy also detected thermally denatured BSA solid alone and in the presence of lipid matrix indicating its suitability for the detection of denatured protein solids in lipid matrices. Despite being in the solid state, conformational changes occurred to BSA upon incorporation into solid lipid matrices. However, the extent of these conformational alterations was found to be dependent on the mixing method employed as indicated by area overlap calculations. For instance, the melting and mixing method imparted negligible effect on BSA secondary structure, whereas the wet granulation mixing method promoted more changes. Size exclusion chromatography analysis depicted the complete dissolution of BSA in the aqueous media employed in the wet granulation method. In conclusion, an ATR FT-IR spectroscopic method was successfully developed to investigate BSA secondary structure in solid lipid matrices following the subtraction of lipid spectral interference. The ATR FT-IR spectroscopy could further be applied to investigate the secondary structure perturbations of therapeutic proteins during their formulation development.

Selecting the optimum number of partial least squares components for the calibration of attenuated total reflectance-mid-infrared spectra of undesigned kerosene samples.

PubMed

Gómez-Carracedo, M P; Andrade, J M; Rutledge, D N; Faber, N M

2007-03-07

Selecting the correct dimensionality is critical for obtaining partial least squares (PLS) regression models with good predictive ability. Although calibration and validation sets are best established using experimental designs, industrial laboratories cannot afford such an approach. Typically, samples are collected in an (formally) undesigned way, spread over time and their measurements are included in routine measurement processes. This makes it hard to evaluate PLS model dimensionality. In this paper, classical criteria (leave-one-out cross-validation and adjusted Wold's criterion) are compared to recently proposed alternatives (smoothed PLS-PoLiSh and a randomization test) to seek out the optimum dimensionality of PLS models. Kerosene (jet fuel) samples were measured by attenuated total reflectance-mid-IR spectrometry and their spectra where used to predict eight important properties determined using reference methods that are time-consuming and prone to analytical errors. The alternative methods were shown to give reliable dimensionality predictions when compared to external validation. By contrast, the simpler methods seemed to be largely affected by the largest changes in the modeling capabilities of the first components.

Infrared reflectance spectra: effects of particle size, provenance and preparation

NASA Astrophysics Data System (ADS)

Su, Yin-Fong; Myers, Tanya L.; Brauer, Carolyn S.; Blake, Thomas A.; Forland, Brenda M.; Szecsody, J. E.; Johnson, Timothy J.

2014-10-01

We have recently developed methods for making more accurate infrared total and diffuse directional - hemispherical reflectance measurements using an integrating sphere. We have found that reflectance spectra of solids, especially powders, are influenced by a number of factors including the sample preparation method, the particle size and morphology, as well as the sample origin. On a quantitative basis we have investigated some of these parameters and the effects they have on reflectance spectra, particularly in the longwave infrared. In the IR the spectral features may be observed as either maxima or minima: In general, upward-going peaks in the reflectance spectrum result from strong surface scattering, i.e. rays that are reflected from the surface without bulk penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. The light signals reflected from solids usually encompass all such effects, but with strong dependencies on particle size and preparation. This paper measures the reflectance spectra in the 1.3 - 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to observe the effects on the spectral features: Bulk materials were ground with a mortar and pestle and sieved to separate the samples into various size fractions between 5 and 500 microns. The median particle size is demonstrated to have large effects on the reflectance spectra. For certain minerals we also observe significant spectral change depending on the geologic origin of the sample. All three such effects (particle size, preparation and provenance) result in substantial change in the reflectance spectra for solid materials; successful identification algorithms will require sufficient flexibility to account for these parameters.

The 'Own Children' fertility estimation procedure: a reappraisal.

PubMed

Avery, Christopher; St Clair, Travis; Levin, Michael; Hill, Kenneth

2013-07-01

The Full Birth History has become the dominant source of estimates of fertility levels and trends for countries lacking complete birth registration. An alternative, the 'Own Children' method, derives fertility estimates from household age distributions, but is now rarely used, partly because of concerns about its accuracy. We compared the estimates from these two procedures by applying them to 56 recent Demographic and Health Surveys. On average, 'Own Children' estimates of recent total fertility rates are 3 per cent lower than birth-history estimates. Much of this difference stems from selection bias in the collection of birth histories: women with more children are more likely to be interviewed. We conclude that full birth histories overestimate total fertility, and that the 'Own Children' method gives estimates of total fertility that may better reflect overall national fertility. We recommend the routine application of the 'Own Children' method to census and household survey data to estimate fertility levels and trends.

An Arduino-Based Experiment Designed to Clarify the Transition to Total Internal Reflection

ERIC Educational Resources Information Center

Atkin, Keith

2018-01-01

The topic of refraction and reflection of light at the boundary of transparent media is a fundamentally important one. The special case of total internal reflection is however commonly misrepresented in elementary textbooks. This paper addresses the problem and describes an experimental procedure for measuring and displaying reflected and…

Application of linear discriminant analysis and Attenuated Total Reflectance Fourier Transform Infrared microspectroscopy for diagnosis of colon cancer.

PubMed

Khanmohammadi, Mohammadreza; Bagheri Garmarudi, Amir; Samani, Simin; Ghasemi, Keyvan; Ashuri, Ahmad

2011-06-01

Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) microspectroscopy was applied for detection of colon cancer according to the spectral features of colon tissues. Supervised classification models can be trained to identify the tissue type based on the spectroscopic fingerprint. A total of 78 colon tissues were used in spectroscopy studies. Major spectral differences were observed in 1,740-900 cm(-1) spectral region. Several chemometric methods such as analysis of variance (ANOVA), cluster analysis (CA) and linear discriminate analysis (LDA) were applied for classification of IR spectra. Utilizing the chemometric techniques, clear and reproducible differences were observed between the spectra of normal and cancer cases, suggesting that infrared microspectroscopy in conjunction with spectral data processing would be useful for diagnostic classification. Using LDA technique, the spectra were classified into cancer and normal tissue classes with an accuracy of 95.8%. The sensitivity and specificity was 100 and 93.1%, respectively.

Hyperspectral Analysis of Soil Total Nitrogen in Subsided Land Using the Local Correlation Maximization-Complementary Superiority (LCMCS) Method

PubMed Central

Lin, Lixin; Wang, Yunjia; Teng, Jiyao; Xi, Xiuxiu

2015-01-01

The measurement of soil total nitrogen (TN) by hyperspectral remote sensing provides an important tool for soil restoration programs in areas with subsided land caused by the extraction of natural resources. This study used the local correlation maximization-complementary superiority method (LCMCS) to establish TN prediction models by considering the relationship between spectral reflectance (measured by an ASD FieldSpec 3 spectroradiometer) and TN based on spectral reflectance curves of soil samples collected from subsided land which is determined by synthetic aperture radar interferometry (InSAR) technology. Based on the 1655 selected effective bands of the optimal spectrum (OSP) of the first derivate differential of reciprocal logarithm ([log{1/R}]′), (correlation coefficients, p < 0.01), the optimal model of LCMCS method was obtained to determine the final model, which produced lower prediction errors (root mean square error of validation [RMSEV] = 0.89, mean relative error of validation [MREV] = 5.93%) when compared with models built by the local correlation maximization (LCM), complementary superiority (CS) and partial least squares regression (PLS) methods. The predictive effect of LCMCS model was optional in Cangzhou, Renqiu and Fengfeng District. Results indicate that the LCMCS method has great potential to monitor TN in subsided lands caused by the extraction of natural resources including groundwater, oil and coal. PMID:26213935

Alternative Measurement Configurations for Extracting Bulk Optical Properties Using an Integrating Sphere Setup.

PubMed

Thennadil, Suresh N; Chen, Yi-Chieh

2017-02-01

The usual approach for estimating bulk optical properties using an integrating sphere measurement setup is by acquiring spectra from three measurement modes namely collimated transmittance (T c ), total transmittance (T d ), and total diffuse reflectance (R d ), followed by the inversion of these measurements using the adding-doubling method. At high scattering levels, accurate acquisition of T c becomes problematic due to the presence of significant amounts of forward-scattered light in this measurement which is supposed to contain only unscattered light. In this paper, we propose and investigate the effectiveness of using alternative sets of integrating sphere measurements that avoid the use of T c and could potentially increase the upper limit of concentrations of suspensions at which bulk optical property measurements can be obtained in the visible-near-infrared (Vis-NIR) region of the spectrum. We examine the possibility of replacing T c with one or more reflectance measurements at different sample thicknesses. We also examine the possibility of replacing both the collimated (T c ) and total transmittance (T d ) measurements with reflectance measurements taken from different sample thicknesses. The analysis presented here indicates that replacing T c with a reflectance measurement can reduce the errors in the bulk scattering properties when scattering levels are high. When only multiple reflectance measurements are used, good estimates of the bulk optical properties can be obtained when the absorption levels are low. In addition, we examine whether there is any advantage in using three measurements instead of two to obtain the reduced bulk scattering coefficient and the bulk absorption coefficient. This investigation is made in the context of chemical and biological suspensions which have a much larger range of optical properties compared to those encountered with tissue.

Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR) Applied to Study the Distribution of Ink Components in Printed Newspapers.

PubMed

Gómez, Nuria; Molleda, Cristina; Quintana, Ester; Carbajo, José M; Rodríguez, Alejandro; Villar, Juan C

2016-09-01

A new method was developed to study how the oil and cyan pigments of cold-set ink are distributed in newspaper thickness. The methodology involved laboratory printing followed by delamination of the printed paper. The unprinted side, printed side, and resulting layers were analyzed using attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR). Three commercial newspapers and black and cyan cold-set inks were chosen for the study. Attenuated total reflection Fourier transform infrared spectroscopy enabled the proportion of oil and cyan pigment on the printed surface and throughout the sheet thickness to be measured. Oil percentage was evaluated as the area increment of the region from 2800 cm(-1) to 3000 cm(-1) The relative amount of cyan pigment was determined as the area of the absorption band at 730 cm(-1) The ink oil was found mainly below half the paper thickness, whereas the pigment was detected at the layers closer to the printed surface, at a depth penetration of less than 15 µm (20% of thickness). Distribution of these two components in paper thickness depended on the type of cold-set ink, the amount of ink transferred, and the newspaper properties. © The Author(s) 2016.

Determination of Zn/Cu ratio and oligoelements in serum samples by total reflection X-ray fluorescence spectrometry for cancer diagnosis

NASA Astrophysics Data System (ADS)

Marcó P., L. M.; Jiménez, E.; Hernández C., E. A.; Rojas, A.; Greaves, E. D.

2001-11-01

The method of quantification using the Compton peak as an internal standard, developed in a previous work, was applied to the routine determination of Fe, Cu, Zn and Se in serum samples from normal individuals and cancer patients by total reflection X-ray fluorescence spectrometry. Samples were classified according to age and sex of the donor, in order to determine reference values for normal individuals. Results indicate that the Zn/Cu ratio and the Cu concentration could prove to be useful tools for cancer diagnosis. Significant differences in these parameters between the normal and cancer group were found for all age ranges. The multielemental character of the technique, coupled with the small amounts of sample required and the short analysis time make it a valuable tool in clinical analysis.

In-situ analysis of fruit anthocyanins by means of total internal reflectance, continuous wave and time-resolved spectroscopy

NASA Astrophysics Data System (ADS)

Zude, Manuela; Spinelli, Lorenzo; Dosche, Carsten; Torricelli, Alessandro

2009-08-01

In sweet cherry (Prunus avium), the red pigmentation is correlated with the fruit maturity stage and can be measured by non-invasive spectroscopy. In the present study, the influence of varying fruit scattering coefficients on the fruit remittance spectrum (cw) were corrected with the effective pathlength and refractive index in the fruit tissue obtained with distribution of time-of-flight (DTOF) readings and total internal reflection fluorescence (TIRF) analysis, respectively. The approach was validated on fruits providing variation in the scattering coefficient outside the calibration sample set. In the validation, the measuring uncertainty when non-invasively analyzing fruits with cw method in comparison with combined application of cw, DTOF, and TIRF measurements showed an increase in r2 up to 22.7 % with, however, high errors in all approaches.

Reference-free spectroscopic determination of fat and protein in milk in the visible and near infrared region below 1000nm using spatially resolved diffuse reflectance fiber probe.

PubMed

Bogomolov, Andrey; Belikova, Valeria; Galyanin, Vladislav; Melenteva, Anastasiia; Meyer, Hans

2017-05-15

New technique of diffuse reflectance spectroscopic analysis of milk fat and total protein content in the visible (Vis) and adjacent near infrared (NIR) region (400-995nm) has been developed and tested. Sample analysis was performed through a probe having eight 200-µm fiber channels forming a linear array. One of the end fibers was used for the illumination and other seven - for the spectroscopic detection of diffusely reflected light. One of the detection channels was used as a reference to normalize the spectra and to convert them into absorbance-equivalent units. The method has been tested experimentally using a designed sample set prepared from industrial raw milk standards with widely varying fat and protein content. To increase the modelling robustness all milk samples were measured in three different homogenization degrees. Comprehensive data analysis has shown the advantage of combining both spectral and spatial resolution in the same measurement and revealed the most relevant channels and wavelength regions. The modelling accuracy was further improved using joint variable selection and preprocessing optimization method based on the genetic algorithm. The root mean-square errors of different validation methods were below 0.10% for fat and below 0.08% for total protein content. Based on the present experimental data, it was computationally shown that the full-spectrum analysis in this method can be replaced by a sensor measurement at several specific wavelengths, for instance, using light-emitting diodes (LEDs) for illumination. Two optimal sensor configurations have been suggested: with nine LEDs for the analysis of fat and seven - for protein content. Both simulated sensors exhibit nearly the same component determination accuracy as corresponding full-spectrum analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Estimation of Anthocyanin Content of Berries by NIR Method

NASA Astrophysics Data System (ADS)

Zsivanovits, G.; Ludneva, D.; Iliev, A.

2010-01-01

Anthocyanin contents of fruits were estimated by VIS spectrophotometer and compared with spectra measured by NIR spectrophotometer (600-1100 nm step 10 nm). The aim was to find a relationship between NIR method and traditional spectrophotometric method. The testing protocol, using NIR, is easier, faster and non-destructive. NIR spectra were prepared in pairs, reflectance and transmittance. A modular spectrocomputer, realized on the basis of a monochromator and peripherals Bentham Instruments Ltd (GB) and a photometric camera created at Canning Research Institute, were used. An important feature of this camera is the possibility offered for a simultaneous measurement of both transmittance and reflectance with geometry patterns T0/180 and R0/45. The collected spectra were analyzed by CAMO Unscrambler 9.1 software, with PCA, PLS, PCR methods. Based on the analyzed spectra quality and quantity sensitive calibrations were prepared. The results showed that the NIR method allows measuring of the total anthocyanin content in fresh berry fruits or processed products without destroying them.

Free-form surface design method for a collimator TIR lens.

PubMed

Tsai, Chung-Yu

2016-04-01

A free-form (FF) surface design method is proposed for a general axial-symmetrical collimator system consisting of a light source and a total internal reflection lens with two coupled FF boundary surfaces. The profiles of the boundary surfaces are designed using a FF surface construction method such that each incident ray is directed (refracted and reflected) in such a way as to form a specified image pattern on the target plane. The light ray paths within the system are analyzed using an exact analytical model and a skew-ray tracing approach. In addition, the validity of the proposed FF design method is demonstrated by means of ZEMAX simulations. It is shown that the illumination distribution formed on the target plane is in good agreement with that specified by the user. The proposed surface construction method is mathematically straightforward and easily implemented in computer code. As such, it provides a useful tool for the design and analysis of general axial-symmetrical optical systems.

Estimation of Anthocyanin Content of Berries by NIR Method

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

Zsivanovits, G.; Ludneva, D.; Iliev, A.

2010-01-21

Anthocyanin contents of fruits were estimated by VIS spectrophotometer and compared with spectra measured by NIR spectrophotometer (600-1100 nm step 10 nm). The aim was to find a relationship between NIR method and traditional spectrophotometric method. The testing protocol, using NIR, is easier, faster and non-destructive. NIR spectra were prepared in pairs, reflectance and transmittance. A modular spectrocomputer, realized on the basis of a monochromator and peripherals Bentham Instruments Ltd (GB) and a photometric camera created at Canning Research Institute, were used. An important feature of this camera is the possibility offered for a simultaneous measurement of both transmittance andmore » reflectance with geometry patterns T0/180 and R0/45. The collected spectra were analyzed by CAMO Unscrambler 9.1 software, with PCA, PLS, PCR methods. Based on the analyzed spectra quality and quantity sensitive calibrations were prepared. The results showed that the NIR method allows measuring of the total anthocyanin content in fresh berry fruits or processed products without destroying them.« less

Retrievals of cloud microphysical properties from the Research Scanning Polarimeter measurements made during PODEX field campaign

NASA Astrophysics Data System (ADS)

Alexandrov, M. D.; Cairns, B.; Sinclair, K.

2013-12-01

We present the retrievals of cloud droplet size distribution parameters (effective radius and variance) from the Research Scanning Polarimeter (RSP) measurements made during NASA's POlarimeter Definition EXperiment (PODEX), which was based in Palmdale, California in January - February 2013. The RSP is an airborne prototype for the Aerosol Polarimetery Sensor (APS), which was built for the NASA Glory Mission project. This instrument measures both polarized and total reflectances in 9 spectral channels with center wavelengths of 410, 470, 555, 670, 865, 960, 1590, 1880 and 2250 nm. The RSP is a push broom scanner making samples at 0.8 degree intervals within 60 degrees from nadir in both forward and backward directions. The data from actual RSP scans is aggregated into "virtual" scans, each consisting of all reflectances (at a variety of scattering angles) from a single point on the ground or at the cloud top. In the case of water clouds the rainbow is observed in the polarized reflectances in the scattering angle range between 135 and 170 degrees. It has a unique signature that is being used to accurately determine the droplet size and is not affected by cloud morphology. Simple parametric fitting algorithm applied to these polarized reflectances provides retrievals of the droplet effective radius and variance assuming a prescribed size distribution shape (gamma distribution). In addition to this, we use a non-parametric method, Rainbow Fourier Transform (RFT), which allows to retrieve the droplet size distribution a parametric model. Of particular interest is the information contained in droplet size distribution width, which is indicative of cloud life cycle. The absorbing band method is also applied to RSP total reflectance observations. The difference in the retrieved droplet size between polarized and absorbing band techniques is expected to reflect the strength of the vertical gradient in cloud liquid water content. In addition to established retrieval techniques, we will use the campaign data to evaluate a new theoretical concept allowing to estimate cloud physical thickness and droplet number concentration using both polarized and total reflectances. During the PODEX campaign the RSP was onboard the NASA's long-range high-altitude ER-2 aircraft together with an array of other remote sensing instrumentation. Correlative sampling measurements from another aircraft were also available. The data obtained during the campaign provides a good opportunity to study cloud properties and to test retrieval algorithms in a variety of locations and atmospheric conditions.

Infrared reflectance spectra: Effects of particle size, provenance and preparation

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

Su, Yin-Fong; Myers, Tanya L.; Brauer, Carolyn S.

2014-09-22

We have recently developed methods for making more accurate infrared total and diffuse directional - hemispherical reflectance measurements using an integrating sphere. We have found that reflectance spectra of solids, especially powders, are influenced by a number of factors including the sample preparation method, the particle size and morphology, as well as the sample origin. On a quantitative basis we have investigated some of these parameters and the effects they have on reflectance spectra, particularly in the longwave infrared. In the IR the spectral features may be observed as either maxima or minima: In general, upward-going peaks in the reflectancemore » spectrum result from strong surface scattering, i.e. rays that are reflected from the surface without bulk penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. The light signals reflected from solids usually encompass all such effects, but with strong dependencies on particle size and preparation. This paper measures the reflectance spectra in the 1.3 – 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to observe the effects on the spectral features: Bulk materials were ground with a mortar and pestle and sieved to separate the samples into various size fractions between 5 and 500 microns. The median particle size is demonstrated to have large effects on the reflectance spectra. For certain minerals we also observe significant spectral change depending on the geologic origin of the sample. All three such effects (particle size, preparation and provenance) result in substantial change in the reflectance spectra for solid materials; successful identification algorithms will require sufficient flexibility to account for these parameters.« less

Infrared and colorimetric characterization of discolored kiln-dried hard maple lumber

Treesearch

Benjamin E. Dawson-Andoh; Michael Wiemann; Laurent Matuana; John Baumgras

2004-01-01

Discoloration of hard maple lumber commonly occurs during kiln-drying. In this study, discolored andnondiscolored kiln-dried hard maple lumber boards were characterized using a colorimetric method and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR). Colorimetric measurements (L*, a*, b*) were found to be in good agreement with visual...

Eukaryotic cell flattening

NASA Astrophysics Data System (ADS)

Bae, Albert; Westendorf, Christian; Erlenkamper, Christoph; Galland, Edouard; Franck, Carl; Bodenschatz, Eberhard; Beta, Carsten

2010-03-01

Eukaryotic cell flattening is valuable for improving microscopic observations, ranging from bright field to total internal reflection fluorescence microscopy. In this talk, we will discuss traditional overlay techniques, and more modern, microfluidic based flattening, which provides a greater level of control. We demonstrate these techniques on the social amoebae Dictyostelium discoideum, comparing the advantages and disadvantages of each method.

Total reflection X-ray fluorescence as a convenient tool for determination of trace elements in microscale gasoline and diesel

NASA Astrophysics Data System (ADS)

Zhang, Airui; Jin, Axiang; Wang, Hai; Wang, Xiaokang; Zha, Pengfei; Wang, Meiling; Song, Xiaoping; Gao, Sitian

2018-03-01

Quantitative determination of trace elements like S, Fe, Cu, Mn and Pb in gasoline and S in diesel is of great importance due to the growing concerns over air pollution, human health and engine failure caused by utilization of gasoline and diesel with these harmful elements. A method of total reflection X-ray fluorescence (TXRF) was developed to measure these harmful trace elements in gasoline and diesel. A variety of factors to affect measurement results, including TXRF parameters, microwave-assisted digestion conditions and internal standard element and its addition, were examined to optimize these experimental procedures. The hydrophobic treatment of the surface of quartz reflectors to support the analyte with neutral silicone solutions could prepare thin films of gasoline and diesel digestion solutions for subsequent TXRF analysis. The proposed method shows good potential and reliability to determine the content of harmful trace elements in gasoline and diesel with high sensitivity and accuracy without drawing different standard calibration curves, and can be easily employed to screen gasoline and diesel in routine quality control and assurance.

Multiple spatially resolved reflection spectroscopy for in vivo determination of carotenoids in human skin and blood

NASA Astrophysics Data System (ADS)

Darvin, Maxim E.; Magnussen, Björn; Lademann, Juergen; Köcher, Wolfgang

2016-09-01

Non-invasive measurement of carotenoid antioxidants in human skin is one of the important tasks to investigate the skin physiology in vivo. Resonance Raman spectroscopy and reflection spectroscopy are the most frequently used non-invasive techniques in dermatology and skin physiology. In the present study, an improved method based on multiple spatially resolved reflection spectroscopy (MSRRS) was introduced. The results obtained were compared with those obtained using the ‘gold standard’ resonance Raman spectroscopy method and showed strong correlations for the total carotenoid concentration (R  =  0.83) as well as for lycopene (R  =  0.80). The measurement stability was confirmed to be better than 10% within the total temperature range from 5 °C to  +  30 °C and pressure contact between the skin and the MSRRS sensor from 800 Pa to 18 000 Pa. In addition, blood samples taken from the subjects were analyzed for carotenoid concentrations. The MSRRS sensor was calibrated on the blood carotenoid concentrations resulting in being able to predict with a correlation of R  =  0.79. On the basis of blood carotenoids it could be demonstrated that the MSRRS cutaneous measurements are not influenced by Fitzpatrick skin types I-VI. The MSRRS sensor is commercially available under the brand name biozoom.

Quantitative analysis of active compounds in pharmaceutical preparations by use of attenuated total-reflection Fourier transform mid-infrared spectrophotometry and the internal standard method.

PubMed

Sastre Toraño, J; van Hattum, S H

2001-10-01

A new method is presented for the quantitative analysis of compounds in pharmaceutical preparations Fourier transform (FT) mid-infrared (MIR) spectroscopy with an attenuated total reflection (ATR) module. Reduction of the quantity of overlapping absorption bands, by interaction of the compound of interest with an appropriate solvent, and the employment of an internal standard (IS), makes MIR suitable for quantitative analysis. Vigabatrin, as active compound in vigabatrin 100-mg capsules, was used as a model compound for the development of the method. Vigabatrin was extracted from the capsule content with water after addition of a sodium thiosulfate IS solution. The extract was concentrated by volume reduction and applied to the FTMIR-ATR module. Concentrations of unknown samples were calculated from the ratio of the vigabatrin band area (1321-1610 cm(-1)) and the IS band area (883-1215 cm(-1)) using a calibration standard. The ratio of the area of the vigabatrin peak to that of the IS was linear with the concentration in the range of interest (90-110 mg, in twofold; n=2). The accuracy of the method in this range was 99.7-100.5% (n=5) with a variability of 0.4-1.3% (n=5). The comparison of the presented method with an HPLC assay showed similar results; the analysis of five vigabatrin 100-mg capsules resulted in a mean concentration of 102 mg with a variation of 2% with both methods.

Development and validation of an environmentally friendly attenuated total reflectance in the mid-infrared region method for the determination of ethanol content in used engine lubrication oil.

PubMed

Hatanaka, Rafael Rodrigues; Sequinel, Rodrigo; Gualtieri, Carlos Eduardo; Tercini, Antônio Carlos Bergamaschi; Flumignan, Danilo Luiz; de Oliveira, José Eduardo

2013-05-15

Lubricating oils are crucial in the operation of automotive engines because they both reduce friction between moving parts and protect against corrosion. However, the performance of lubricant oil may be affected by contaminants, such as gasoline, diesel, ethanol, water and ethylene glycol. Although there are many standard methods and studies related to the quantification of contaminants in lubricant oil, such as gasoline and diesel oil, to the best of our knowledge, no methods have been reported for the quantification of ethanol in used Otto cycle engine lubrication oils. Therefore, this work aimed at the development and validation of a routine method based on partial least-squares multivariate analysis combined with attenuated total reflectance in the mid-infrared region to quantify ethanol content in used lubrication oil. The method was validated based on its figures of merit (using the net analyte signal) as follows: limit of detection (0.049%), limit of quantification (0.16%), accuracy (root mean square error of prediction=0.089% w/w), repeatability (0.05% w/w), fit (R(2)=0.9997), mean selectivity (0.047), sensitivity (0.011), inverse analytical sensitivity (0.016% w/w(-1)) and signal-to-noise ratio (max: 812.4 and min: 200.9). The results show that the proposed method can be routinely implemented for the quality control of lubricant oils. Copyright © 2013 Elsevier B.V. All rights reserved.

Visualization of hemodynamics and light scattering in exposed brain of rat using multispectral image reconstruction based on Wiener estimation method

NASA Astrophysics Data System (ADS)

Nishidate, Izumi; Ishizuka, Tomohiro; Yoshida, Keiichiro; Kawauchi, Satoko; Sato, Shunichi; Sato, Manabu

2015-07-01

We investigate a method to estimate the spectral images of reduced scattering coefficients and the absorption coefficients of in vivo exposed brain tissues in the range from visible to near-infrared wavelength (500-760 nm) based on diffuse reflectance spectroscopy using a digital RGB camera. In the proposed method, the multi-spectral reflectance images of in vivo exposed brain are reconstructed from the digital red, green, blue images using the Wiener estimation algorithm. The Monte Carlo simulation-based multiple regression analysis for the absorbance spectra is then used to specify the absorption and scattering parameters of brain tissue. In this analysis, the concentration of oxygenated hemoglobin and that of deoxygenated hemoglobin are estimated as the absorption parameters whereas the scattering amplitude a and the scattering power b in the expression of μs'=aλ-b as the scattering parameters, respectively. The spectra of absorption and reduced scattering coefficients are reconstructed from the absorption and scattering parameters, and finally, the spectral images of absorption and reduced scattering coefficients are estimated. We performed simultaneous recordings of spectral diffuse reflectance images and of the electrophysiological signals for in vivo exposed rat brain during the cortical spreading depression evoked by the topical application of KCl. Changes in the total hemoglobin concentration and the tissue oxygen saturation imply the temporary change in cerebral blood flow during CSD. Change in the reduced scattering coefficient was observed before the profound increase in the total hemoglobin concentration, and its occurrence was synchronized with the negative dc shift of the local field potential.

Comparison of laboratory and field remote sensing methods to measure forage quality.

PubMed

Guo, Xulin; Wilmshurst, John F; Li, Zhaoqin

2010-09-01

Recent research in range ecology has emphasized the importance of forage quality as a key indicator of rangeland condition. However, we lack tools to evaluate forage quality at scales appropriate for management. Using canopy reflectance data to measure forage quality has been conducted at both laboratory and field levels separately, but little work has been conducted to evaluate these methods simultaneously. The objective of this study is to find a reliable way of assessing grassland quality through measuring forage chemistry with reflectance. We studied a mixed grass ecosystem in Grasslands National Park of Canada and surrounding pastures, located in southern Saskatchewan. Spectral reflectance was collected at both in-situ field level and in the laboratory. Vegetation samples were collected at each site, sorted into the green grass portion, and then sent to a chemical company for measuring forage quality variables, including protein, lignin, ash, moisture at 135 °C, Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), Total Digestible, Digestible Energy, Net Energy for Lactation, Net Energy for Maintenance, and Net Energy for Gain. Reflectance data were processed with the first derivative transformation and continuum removal method. Correlation analysis was conducted on spectral and forage quality variables. A regression model was further built to investigate the possibility of using canopy spectral measurements to predict the grassland quality. Results indicated that field level prediction of protein of mixed grass species was possible (r² = 0.63). However, the relationship between canopy reflectance and the other forage quality variables was not strong.

Alterations in Retinal Layer Thickness and Reflectance at Different Stages of Diabetic Retinopathy by En Face Optical Coherence Tomography

PubMed Central

Wanek, Justin; Blair, Norman P.; Chau, Felix Y.; Lim, Jennifer I.; Leiderman, Yannek I.; Shahidi, Mahnaz

2016-01-01

Purpose This article reports a method for en face optical coherence tomography (OCT) imaging and quantitative assessment of alterations in both thickness and reflectance of individual retinal layers at different stages of diabetic retinopathy (DR). Methods High-density OCT raster volume scans were acquired in 29 diabetic subjects divided into no DR (NDR) or non-proliferative DR (NPDR) groups and 22 control subjects (CNTL). A customized image segmentation method identified eight retinal layer interfaces and generated en face thickness maps and reflectance images for nerve fiber layer (NFL), ganglion cell and inner plexiform layers (GCLIPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), photoreceptor outer segment layer (OSL), and retinal pigment epithelium (RPE). Mean thickness and intensity values were calculated in nine macular subfields for each retinal layer. Results En face thickness maps and reflectance images of retinal layers in CNTL subjects corresponded to normal retinal anatomy. Total retinal thickness correlated negatively with age in nasal subfields (R ≤−0.31; P ≤ 0.03, N = 51). In NDR subjects, NFL and OPL thickness were decreased (P = 0.05), and ONL thickness was increased (P = 0.04) compared to CNTL. In NPDR subjects, GCLIPL thickness was increased in perifoveal subfields (P < 0.05) and INL intensity was higher in all macular subfields (P = 0.04) compared to CNTL. Conclusions Depth and spatially resolved retinal thickness and reflectance measurements are potential biomarkers for assessment and monitoring of DR. PMID:27409491

Attenuated total internal reflection infrared microspectroscopic imaging using a large-radius germanium internal reflection element and a linear array detector.

PubMed

Patterson, Brian M; Havrilla, George J

2006-11-01

The number of techniques and instruments available for Fourier transform infrared (FT-IR) microspectroscopic imaging has grown significantly over the past few years. Attenuated total internal reflectance (ATR) FT-IR microspectroscopy reduces sample preparation time and has simplified the analysis of many difficult samples. FT-IR imaging has become a powerful analytical tool using either a focal plane array or a linear array detector, especially when coupled with a chemometric analysis package. The field of view of the ATR-IR microspectroscopic imaging area can be greatly increased from 300 x 300 microm to 2500 x 2500 microm using a larger internal reflection element of 12.5 mm radius instead of the typical 1.5 mm radius. This gives an area increase of 70x before aberrant effects become too great. Parameters evaluated include the change in penetration depth as a function of beam displacement, measurements of the active area, magnification factor, and change in spatial resolution over the imaging area. Drawbacks such as large file size will also be discussed. This technique has been successfully applied to the FT-IR imaging of polydimethylsiloxane foam cross-sections, latent human fingerprints, and a model inorganic mixture, which demonstrates the usefulness of the method for pharmaceuticals.

Microscopic iron metal on glass and minerals - A tool for studying regolith maturity

NASA Technical Reports Server (NTRS)

Allen, C. C.; Morris, R. V.; Lauer, H. V., Jr.; Mckay, D. S.

1993-01-01

A novel method of producing mixtures of glass or minerals with iron metal is presented. A portion of the Fe(2+) in basaltic glass and minerals can be reduced to metal in a few hours at 1100 C and an oxygen fugacity well below the iron-wustite buffer. Part of the iron metals forms rounded submicrometer blebs on the surfaces and in some cases within the grains. A concentration of such blebs equivalent to 20-30 percent of a grain's surface area can totally dominate the reflectance spectra of basaltic glass, pyroxene, and olivine. The production of optically opaque iron metal blebs, combined with the decline in Fe(2+), affects the glass and mineral reflectance spectra in three ways: by lowering the overall reflectivity, reducing the spectral contrast of absorption features, and producing a continuum with a general rise in reflectivity toward longer wavelengths.

Advantages of infrared transflection micro spectroscopy and paraffin-embedded sample preparation for biological studies

NASA Astrophysics Data System (ADS)

Yao, Jie; Li, Qian; Zhou, Bo; Wang, Dan; Wu, Rie

2018-04-01

Fourier-Transform Infrared micro-spectroscopy is an excellent method for biological analyses. In this paper, series metal coating films on ITO glass were prepared by the electrochemical method and the different thicknesses of paraffin embedding rat's brain tissue on the substrates were studied by IR micro-spetroscopy in attenuated total reflection (ATR) mode and transflection mode respectively. The Co-Ni-Cu alloy coating film with low cost is good reflection substrates for the IR analysis. The infrared microscopic transflection mode needs not to touch the sample at all and can get the IR spectra with higher signal to noise ratios. The Paraffin-embedding method allows tissues to be stored for a long time for re-analysis to ensure the traceability of the sample. Also it isolates the sample from the metal and avoids the interaction of biological tissue with the metals. The best thickness of the tissues is 4 μm.

Analysis of total oil and fatty acids composition by near infrared reflectance spectroscopy in edible nuts

NASA Astrophysics Data System (ADS)

Kandala, Chari V.; Sundaram, Jaya

2014-10-01

Near Infrared (NIR) Reflectance spectroscopy has established itself as an important tool in quantifying water and oil present in various food materials. It is rapid and nondestructive, easier to use, and does not require processing the samples with corrosive chemicals that would render them non-edible. Earlier, the samples had to be ground into powder form before making any measurements. With the development of new soft ware packages, NIR techniques could now be used in the analysis of intact grain and nuts. While most of the commercial instruments presently available work well with small grain size materials such as wheat and corn, the method present here is suitable for large kernel size products such as shelled or in-shell peanuts. Absorbance spectra were collected from 400 nm to 2500 nm using a NIR instrument. Average values of total oil contents (TOC) of peanut samples were determined by standard extraction methods, and fatty acids were determined using gas chromatography. Partial least square (PLS) analysis was performed on the calibration set of absorption spectra, and models were developed for prediction of total oil and fatty acids. The best model was selected based on the coefficient of determination (R2), Standard error of prediction (SEP) and residual percent deviation (RPD) values. Peanut samples analyzed showed RPD values greater than 5.0 for both absorbance and reflectance models and thus could be used for quality control and analysis. Ability to rapidly and nondestructively measure the TOC, and analyze the fatty acid composition, will be immensely useful in peanut varietal improvement as well as in the grading process of grain and nuts.

Determination of protein concentration in raw milk by mid-infrared fourier transform infrared/attenuated total reflectance spectroscopy.

PubMed

Etzion, Y; Linker, R; Cogan, U; Shmulevich, I

2004-09-01

This study investigates the potential use of attenuated total reflectance spectroscopy in the mid-infrared range for determining protein concentration in raw cow milk. The determination of protein concentration is based on the characteristic absorbance of milk proteins, which includes 2 absorbance bands in the 1500 to 1700 cm(-1) range, known as the amide I and amide II bands, and absorbance in the 1060 to 1100 cm(-1) range, which is associated with phosphate groups covalently bound to casein proteins. To minimize the influence of the strong water band (centered around 1640 cm(-1)) that overlaps with the amide I and amide II bands, an optimized automatic procedure for accurate water subtraction was applied. Following water subtraction, the spectra were analyzed by 3 methods, namely simple band integration, partial least squares (PLS) and neural networks. For the neural network models, the spectra were first decomposed by principal component analysis (PCA), and the neural network inputs were the spectra principal components scores. In addition, the concentrations of 2 constituents expected to interact with the protein (i.e., fat and lactose) were also used as inputs. These approaches were tested with 235 spectra of standardized raw milk samples, corresponding to 26 protein concentrations in the 2.47 to 3.90% (weight per volume) range. The simple integration method led to very poor results, whereas PLS resulted in prediction errors of about 0.22% protein. The neural network approach led to prediction errors of 0.20% protein when based on PCA scores only, and 0.08% protein when lactose and fat concentrations were also included in the model. These results indicate the potential usefulness of Fourier transform infrared/attenuated total reflectance spectroscopy for rapid, possibly online, determination of protein concentration in raw milk.

Exploring the Effects of Cloud Vertical Structure on Cloud Microphysical Retrievals based on Polarized Reflectances

NASA Astrophysics Data System (ADS)

Miller, D. J.; Zhang, Z.; Platnick, S. E.; Ackerman, A. S.; Cornet, C.; Baum, B. A.

2013-12-01

A polarized cloud reflectance simulator was developed by coupling an LES cloud model with a polarized radiative transfer model to assess the capabilities of polarimetric cloud retrievals. With future remote sensing campaigns like NASA's Aerosols/Clouds/Ecosystems (ACE) planning to feature advanced polarimetric instruments it is important for the cloud remote sensing community to understand the retrievable information available and the related systematic/methodical limitations. The cloud retrieval simulator we have developed allows us to probe these important questions in a realistically relevant test bed. Our simulator utilizes a polarized adding-doubling radiative transfer model and an LES cloud field from a DHARMA simulation (Ackerman et al. 2004) with cloud properties based on the stratocumulus clouds observed during the DYCOMS-II field campaign. In this study we will focus on how the vertical structure of cloud microphysics can influence polarized cloud effective radius retrievals. Numerous previous studies have explored how retrievals based on total reflectance are affected by cloud vertical structure (Platnick 2000, Chang and Li 2002) but no such studies about the effects of vertical structure on polarized retrievals exist. Unlike the total cloud reflectance, which is predominantly multiply scattered light, the polarized reflectance is primarily the result of singly scattered photons. Thus the polarized reflectance is sensitive to only the uppermost region of the cloud (tau~<1) where photons can scatter once and still escape before being scattered again. This means that retrievals based on polarized reflectance have the potential to reveal behaviors specific to the cloud top. For example cloud top entrainment of dry air, a major influencer on the microphysical development of cloud droplets, can be potentially studied with polarimetric retrievals.

A novel and practical approach for determination of the acoustic nonlinearity parameter using a pulse-echo method

NASA Astrophysics Data System (ADS)

Jeong, Hyunjo; Zhang, Shuzeng; Barnard, Dan; Li, Xiongbing

2016-02-01

Measurements of the acoustic nonlinearity parameter β are frequently made for early detection of damage in various materials. The practical implementation of the measurement technique has been limited to the through-transmission setup for determining the nonlinearity parameter of the second harmonic wave. In this work, a feasibility study is performed to assess the possibility of using pulse-echo methods in determining the nonlinearity parameter β of solids with a stress-free boundary. The multi-Gaussian beam model is developed based on the quasilinear theory of the KZK equation. Simulation results and discussion are presented for the reflected beam fields of the fundamental and second harmonic waves, the uncorrected β behavior and the properties of total correction that incorporate reflection, attenuation and diffraction effects.

An Arduino-based experiment designed to clarify the transition to total internal reflection

NASA Astrophysics Data System (ADS)

Atkin, Keith

2018-03-01

The topic of refraction and reflection of light at the boundary of transparent media is a fundamentally important one. The special case of total internal reflection is however commonly misrepresented in elementary textbooks. This paper addresses the problem and describes an experimental procedure for measuring and displaying reflected and transmitted light intensities using readily available components and the Arduino microcontroller.

Frequency selective reflection and transmission at a layer composed of a periodic dielectric

NASA Technical Reports Server (NTRS)

Bertoni, Henry L.; Cheo, Li-Hsiang S.; Tamir, Theodor

1987-01-01

The feasibility of using a periodic dielectric layer, composed of alternating bars having dielectric constants epsilon sub 1 and epsilon sub 2, as a frequency selective subreflector in order to permit feed separation in large aperture reflecting antenna systems was examined. For oblique incidence, it is found that total transmission and total reflection can be obtained at different frequencies for proper choices of epsilon sub 1, epsilon 2, and the geometric parameters. The frequencies of total reflection and transmission can be estimated from wave phenomena occurring in a layer of uniform dielectric constant equal to the average for the periodic layers. About some of the frequencies of total transmission, the bandwidth for 90% transmission is found to be 40%. However, the bandwidth for 90% reflection is always found to be much narrower; the greatest value found being 2.5%.

Near-peer role modeling: Can fourth-year medical students, recognized for their humanism, enhance reflection among second-year students in a physical diagnosis course?

PubMed Central

McEvoy, Mimi; Pollack, Staci; Dyche, Lawrence; Burton, William

2016-01-01

Introduction Humanism is cultivated through reflection and self-awareness. We aimed to employ fourth-year medical students, recognized for their humanism, to facilitate reflective sessions for second-year medical students with the intention of positively influencing reflective process toward humanistic development. Methods/Analysis A total of 186 students were randomly assigned to one of three comparison arms: eight groups of eight students (64 students) were facilitated by a fourth-year student who was a Gold Humanism Honor Society member (GHHS); eight groups (64 students) by a volunteer non-GHHS student; and seven groups (58 students) were non-facilitated. Before sessions, second-year students set learning goals concerning interactions with patients; fourth-year students received training materials on facilitation. Groups met twice during their 10 clinical site visits. At the last session, students completed a reflective assignment on their goal progress. Comparative mixed method analyses were conducted among the three comparison arms on reflection (reflective score on in-session assignment) and session satisfaction (survey) in addition to a thematic analysis of responses on the in-session assignment. Results We found significant differences among all three comparison arms on students’ reflective scores (p=0.0003) and satisfaction (p=0.0001). T-tests comparing GHHS- and non-GHHS-facilitated groups showed significantly higher mean reflective scores for GHHS-facilitated groups (p=0.033); there were no differences on session satisfaction. Thematic analysis of students’ reflections showed attempts at self-examination, but lacked depth in addressing emotions. There was a common focus on achieving comfort and confidence in clinical skills performance. Discussion/Conclusions Near peers, recognized for their humanism, demonstrated significant influence in deepening medical students’ reflections surrounding patient interactions or humanistic development. Overall, students preferred facilitated to non-facilitated peer feedback forums. This model holds promise for enhancing self-reflection in medical education, but needs further exploration to determine behavioral effects. PMID:27600828

Near-peer role modeling: Can fourth-year medical students, recognized for their humanism, enhance reflection among second-year students in a physical diagnosis course?

PubMed

McEvoy, Mimi; Pollack, Staci; Dyche, Lawrence; Burton, William

2016-01-01

Introduction Humanism is cultivated through reflection and self-awareness. We aimed to employ fourth-year medical students, recognized for their humanism, to facilitate reflective sessions for second-year medical students with the intention of positively influencing reflective process toward humanistic development. Methods/Analysis A total of 186 students were randomly assigned to one of three comparison arms: eight groups of eight students (64 students) were facilitated by a fourth-year student who was a Gold Humanism Honor Society member (GHHS); eight groups (64 students) by a volunteer non-GHHS student; and seven groups (58 students) were non-facilitated. Before sessions, second-year students set learning goals concerning interactions with patients; fourth-year students received training materials on facilitation. Groups met twice during their 10 clinical site visits. At the last session, students completed a reflective assignment on their goal progress. Comparative mixed method analyses were conducted among the three comparison arms on reflection (reflective score on in-session assignment) and session satisfaction (survey) in addition to a thematic analysis of responses on the in-session assignment. Results We found significant differences among all three comparison arms on students' reflective scores (p=0.0003) and satisfaction (p=0.0001). T-tests comparing GHHS- and non-GHHS-facilitated groups showed significantly higher mean reflective scores for GHHS-facilitated groups (p=0.033); there were no differences on session satisfaction. Thematic analysis of students' reflections showed attempts at self-examination, but lacked depth in addressing emotions. There was a common focus on achieving comfort and confidence in clinical skills performance. Discussion/Conclusions Near peers, recognized for their humanism, demonstrated significant influence in deepening medical students' reflections surrounding patient interactions or humanistic development. Overall, students preferred facilitated to non-facilitated peer feedback forums. This model holds promise for enhancing self-reflection in medical education, but needs further exploration to determine behavioral effects.

Rapid determination of Swiss cheese composition by Fourier transform infrared/attenuated total reflectance spectroscopy.

PubMed

Rodriguez-Saona, L E; Koca, N; Harper, W J; Alvarez, V B

2006-05-01

There is a need for rapid and simple techniques that can be used to predict the quality of cheese. The aim of this research was to develop a simple and rapid screening tool for monitoring Swiss cheese composition by using Fourier transform infrared spectroscopy. Twenty Swiss cheese samples from different manufacturers and degree of maturity were evaluated. Direct measurements of Swiss cheese slices (approximately 0.5 g) were made using a MIRacle 3-reflection diamond attenuated total reflectance (ATR) accessory. Reference methods for moisture (vacuum oven), protein content (Kjeldahl), and fat (Babcock) were used. Calibration models were developed based on a cross-validated (leave-one-out approach) partial least squares regression. The information-rich infrared spectral range for Swiss cheese samples was from 3,000 to 2,800 cm(-1) and 1,800 to 900 cm(-1). The performance statistics for cross-validated models gave estimates for standard error of cross-validation of 0.45, 0.25, and 0.21% for moisture, protein, and fat respectively, and correlation coefficients r > 0.96. Furthermore, the ATR infrared protocol allowed for the classification of cheeses according to manufacturer and aging based on unique spectral information, especially of carbonyl groups, probably due to their distinctive lipid composition. Attenuated total reflectance infrared spectroscopy allowed for the rapid (approximately 3-min analysis time) and accurate analysis of the composition of Swiss cheese. This technique could contribute to the development of simple and rapid protocols for monitoring complex biochemical changes, and predicting the final quality of the cheese.

A comparative study of mid-infrared diffuse reflection (DR) and attenuated total reflection (ATR) spectroscopy for the detection of fungal infection on RWA2-corn.

PubMed

Kos, Gregor; Krska, Rudolf; Lohninger, Hans; Griffiths, Peter R

2004-01-01

An investigation into the rapid detection of mycotoxin-producing fungi on corn by two mid-infrared spectroscopic techniques was undertaken. Corn samples from a single genotype (RWA2, blanks, and contaminated with Fusarium graminearum) were ground, sieved and, after appropriate sample preparation, subjected to mid-infrared spectroscopy using two different accessories (diffuse reflection and attenuated total reflection). The measured spectra were evaluated with principal component analysis (PCA) and the blank and contaminated samples were classified by cluster analysis. Reference data for fungal metabolites were obtained with conventional methods. After extraction and clean-up, each sample was analyzed for the toxin deoxynivalenol (DON) by gas chromatography with electron capture detection (GC-ECD) and ergosterol (a parameter for the total fungal biomass) by high-performance liquid chromatography with diode array detection (HPLC-DAD). The concentration ranges for contaminated samples were 880-3600 microg/kg for ergosterol and 300-2600 microg/kg for DON. Classification efficiency was 100% for ATR spectra. DR spectra did not show as obvious a clustering of contaminated and blank samples. Results and trends were also observed in single spectra plots. Quantification using a PLS1 regression algorithm showed good correlation with DON reference data, but a rather high standard error of prediction (SEP) with 600 microg/kg (DR) and 490 microg/kg (ATR), respectively, for ergosterol. Comparing measurement procedures and results showed advantages for the ATR technique, mainly owing to its ease of use and the easier interpretation of results that were better with respect to classification and quantification.

Juvenile Delinquent Girls Reflect Learning in Schools and Offer Suggestions

ERIC Educational Resources Information Center

Sanger, Dixie; Stremlau, Aliza; Ritzman, Mitzi; Snow, Pamela

2010-01-01

Qualitative methods were used to conduct interviews of 41 female juvenile delinquents residing in a correctional facility to understand how participants would have improved learning in their former school if they had been the teachers. A total of 27 of 41 participants provided 70 comments that resulted in 93 meaning units/codes that emerged into 4…

Preliminary evidence of oxidation in standard oven drying of cotton: attenuated total reflectance/ Fourier transform spectroscopy, colorimetry, and particulate matter formation

USDA-ARS?s Scientific Manuscript database

Moisture is paramount to cotton fiber properties dictating harvesting, ginning, storage and spinning as well as others. Currently, oven drying in air is often utilized to generate the percentage of moisture in cotton fibers. Karl Fischer Titration another method for cotton moisture, has been compa...

Seismic reflection response from cross-correlations of ambient vibrations on non-conventional hidrocarbon reservoir

NASA Astrophysics Data System (ADS)

Huerta, F. V.; Granados, I.; Aguirre, J.; Carrera, R. Á.

2017-12-01

Nowadays, in hydrocarbon industry, there is a need to optimize and reduce exploration costs in the different types of reservoirs, motivating the community specialized in the search and development of alternative exploration geophysical methods. This study show the reflection response obtained from a shale gas / oil deposit through the method of seismic interferometry of ambient vibrations in combination with Wavelet analysis and conventional seismic reflection techniques (CMP & NMO). The method is to generate seismic responses from virtual sources through the process of cross-correlation of records of Ambient Seismic Vibrations (ASV), collected in different receivers. The seismic response obtained is interpreted as the response that would be measured in one of the receivers considering a virtual source in the other. The acquisition of ASV records was performed in northern of Mexico through semi-rectangular arrays of multi-component geophones with instrumental response of 10 Hz. The in-line distance between geophones was 40 m while in cross-line was 280 m, the sampling used during the data collection was 2 ms and the total duration of the records was 6 hours. The results show the reflection response of two lines in the in-line direction and two in the cross-line direction for which the continuity of coherent events have been identified and interpreted as reflectors. There is certainty that the events identified correspond to reflections because the time-frequency analysis performed with the Wavelet Transform has allowed to identify the frequency band in which there are body waves. On the other hand, the CMP and NMO techniques have allowed to emphasize and correct the reflection response obtained during the correlation processes in the frequency band of interest. The results of the processing and analysis of ASV records through the seismic interferometry method have allowed us to see interesting results in light of the cross-correlation process in combination with the Wavelet analysis and conventional seismic reflection techniques. Therefore it was possible to recover the seismic response on each analyzed source-receiver pair, allowing us to obtain the reflection response of each analyzed seismic line.

Characterization of pigments and colors used in ancient Egyptian boat models

NASA Astrophysics Data System (ADS)

Hühnerfuβ, Katja; von Bohlen, Alex; Kurth, Dieter

2006-11-01

The analyses of pigments originating from well dated ancient boat models found in Egyptian graves were used for characterization and for dating tasks of unknown objects. A nearly destruction free sampling technique using cotton buds was applied for sampling these valuable artifacts for a subsequent Total Reflection X-Ray Fluorescence Spectrometry (TXRF) analysis. Two relevant collections of Egyptian object of art were at our disposal, one of the Ägyptisches Museum Berlin and the second of the British Museum London. Three groups of colors were studied, they originate from white, red and blue/green paints, respectively. The results of the analyses performed on micro-amounts of paints (< 1 μg) show that some artifacts were misclassified and belong to other epochs. Some others were retouched with modern colors. In general, it can be stated that results obtained by Total Reflection X-Ray Fluorescence Spectrometry may dissipate some uncertainties when applying classical archaeological dating methods.

Application of attenuated total reflectance Fourier transform infrared spectroscopy for determination of cefixime in oral pharmaceutical formulations.

PubMed

Kandhro, Aftab A; Laghari, Abdul Hafeez; Mahesar, Sarfaraz A; Saleem, Rubina; Nelofar, Aisha; Khan, Salman Tariq; Sherazi, S T H

2013-11-01

A quick and reliable analytical method for the quantitative assessment of cefixime in orally administered pharmaceutical formulations is developed by using diamond cell attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy as an easy procedure for quality control laboratories. The standards for calibration were prepared in aqueous medium ranging from 350 to 6000mg/kg. The calibration model was developed based on partial least square (PLS) using finger print region of FT-IR spectrum in the range from 1485 to 887cm(-1). Excellent coefficient of determination (R(2)) was achieved as high as 0.99976 with root mean square error of 44.8 for calibration. The application of diamond cell (smart accessory) ATR FT-IR proves a reliable determination of cefixime in pharmaceutical formulations to assess the quality of the final product. Copyright © 2013 Elsevier B.V. All rights reserved.

Surface and downhole shear wave seismic methods for thick soil site investigations

USGS Publications Warehouse

Hunter, J.A.; Benjumea, B.; Harris, J.B.; Miller, R.D.; Pullan, S.E.; Burns, R.A.; Good, R.L.

2002-01-01

Shear wave velocity-depth information is required for predicting the ground motion response to earthquakes in areas where significant soil cover exists over firm bedrock. Rather than estimating this critical parameter, it can be reliably measured using a suite of surface (non-invasive) and downhole (invasive) seismic methods. Shear wave velocities from surface measurements can be obtained using SH refraction techniques. Array lengths as large as 1000 m and depth of penetration to 250 m have been achieved in some areas. High resolution shear wave reflection techniques utilizing the common midpoint method can delineate the overburden-bedrock surface as well as reflecting boundaries within the overburden. Reflection data can also be used to obtain direct estimates of fundamental site periods from shear wave reflections without the requirement of measuring average shear wave velocity and total thickness of unconsolidated overburden above the bedrock surface. Accurate measurements of vertical shear wave velocities can be obtained using a seismic cone penetrometer in soft sediments, or with a well-locked geophone array in a borehole. Examples from thick soil sites in Canada demonstrate the type of shear wave velocity information that can be obtained with these geophysical techniques, and show how these data can be used to provide a first look at predicted ground motion response for thick soil sites. ?? 2002 Published by Elsevier Science Ltd.

Evaluation of light scattering properties and chromophore concentrations in skin tissue based on diffuse reflectance signals at isosbestic wavelengths of hemoglobin

NASA Astrophysics Data System (ADS)

Yokokawa, Takumi; Nishidate, Izumi

2016-04-01

We investigate a method to evaluate light-scattering properties and chromophore concentrations in human skin tissue through diffuse reflectance spectroscopy using the reflectance signals acquired at isosbestic wavelengths of hemoglobin (420, 450, 500, and 585 nm). In the proposed method, Monte Carlo simulation-based empirical formulas are used to specify the scattering parameters of skin tissue, such as the scattering amplitude a and the scattering power b, as well as the concentration of melanin C m and the total blood concentration C tb. The use of isosbestic wavelengths of hemoglobin enables the values of C m, C tb, a, and b to be estimated independently of the oxygenation of hemoglobin. The spectrum of the reduced scattering coefficient is reconstructed from the scattering parameters. Experiments using in vivo human skin tissues were performed to confirm the feasibility of the proposed method for evaluating the changes in scattering properties and chromophore concentrations in skin tissue. The experimental results revealed that light scattering is significantly reduced by the application of a glycerol solution, which indicates an optical clearing effect due to osmotic dehydration and the matching of the refractive indices of scatterers in the epidermis.

Characterization of Printing Inks Using DART-Q-TOF-MS and Attenuated Total Reflectance (ATR) FTIR.

PubMed

Williamson, Rhett; Raeva, Anna; Almirall, Jose R

2016-05-01

The rise in improved and widely accessible printing technology has resulted in an interest to develop rapid and minimally destructive chemical analytical techniques that can characterize printing inks for forensic document analysis. Chemical characterization of printing inks allows for both discrimination of inks originating from different sources and the association of inks originating from the same source. Direct analysis in real-time mass spectrometry (DART-MS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were used in tandem to analyze four different classes of printing inks: inkjets, toners, offset, and intaglio. A total of 319 samples or ~ 80 samples from each class were analyzed directly on a paper substrate using the two methods. DART-MS was found to characterize the semi-volatile polymeric vehicle components, while ATR-FTIR provided chemical information associated with the bulk components of these inks. Complimentary data results in improved discrimination when both techniques are used in succession resulting in >96% discrimination for all toners, 95% for all inkjets, >92% for all offset, and >54% for all intaglio inks. © 2016 American Academy of Forensic Sciences.

The effects of particle size on the optical properties and surface roughness of a glass-balloon-filled black paint

NASA Technical Reports Server (NTRS)

Heslin, T.; Heaney, J.; Harper, M.

1974-01-01

The effects of particle size on the optical properties and surface roughness of a glass-balloon-filled, carbon-pigmented paint were studied in order to develop a diffuse-reflecting, low-total-reflectance, low-outgassing black paint. Particle sizes ranged between 20 microns and 74 microns. Surface roughness was found to increase with increasing particle size. Relative total reflectance at near-normal incidence (MgO standard) of the filled paints was less than for the unfilled paint between 230 nm and 1800 nm. Total absolute reflectance at 546 nm decreased with increasing particle size at grazing angles of incidence. Near-normal, total emittance was greater for the filled paints than for the unfilled paint. Specularity decreased with increasing particle size over the range studied.

Vegetation Red-edge Spectral Modeling for Solar-induced Chlorophyll Fluorescence Retrieval at O2-B Band

NASA Astrophysics Data System (ADS)

Huang, C.; Zhang, L.; Qiao, N.; Zhang, X.; Li, Y.

2015-12-01

Remotely sensed solar-induced chlorophyll fluorescence (SIF) has been considered an ideal probe in monitoring global vegetation photosynthesis. However, challenges in accurate estimate of faint SIF (less than 5% of the total reflected radiation in near infrared bands) from the observed apparent reflected radiation greatly limit its wide applications. Currently, the telluric O2-B (~688nm) and O2-A (~761nm) have been proved to be capable of SIF retrieval based on Fraunhofer line depth (FLD) principle. They may still work well even using conventional ground-based commercial spectrometers with typical spectral resolutions of 2~5 nm and high enough signal-to-noise ratio (e.g., the ASD spectrometer). Nevertheless, almost all current FLD based algorithms were mainly developed for O2-A, a few concentrating on the other SIF emission peak in O2-B. One of the critical reasons is that it is very difficult to model the sudden varying reflectance around O2-B band located in the red-edge spectral region (about 680-800 nm). This study investigates a new method by combining the established inverted Gaussian reflectance model (IGM) and FLD principle using diurnal canopy spectra with relative low spectral resolutions of 1 nm (FluorMOD simulations) and 3 nm (measured by ASD spectrometer) respectively. The IGM has been reported to be an objective and good method to characterize the entire vegetation red-edge reflectance. Consequently, the proposed SIF retrieval method (hereinafter called IGMFLD) could exploit all the spectral information along the whole red-edge (680-800 nm) to obtain more reasonable reflectance and fluorescence correction coefficients than traditional FLD methods such as the iFLD. Initial results show that the IGMFLD can better capture the spectrally non-linear characterization of the reflectance in 680-800 nm and thereby yields much more accurate SIFs in O2-B than typical FLD methods, including sFLD, 3FLD and iFLD (see figure 1). Finally, uncertainties and prospect of the IGM-FLD, in contrast with sFLD, 3FLD and iFLD, were discussed here. This study may provide a test-bed for developing more robust methods to retrieve SIF in O2-B from aircraft (e.g. AisaIBIS fluorescence imager) or satellite (FLEX-FLORIS) remote sensing measurements.

Measurement of conjugated linoleic acid (CLA) in CLA-rich soy oil by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR).

PubMed

Kadamne, Jeta V; Jain, Vishal P; Saleh, Mohammed; Proctor, Andrew

2009-11-25

Conjugated linoleic acid (CLA) isomers in oils are currently measured as fatty acid methyl esters by a gas chromatography-flame ionization detector (GC-FID) technique, which requires approximately 2 h to complete the analysis. Hence, we aim to develop a method to rapidly determine CLA isomers in CLA-rich soy oil. Soy oil with 0.38-25.11% total CLA was obtained by photo-isomerization of 96 soy oil samples for 24 h. A sample was withdrawn at 30 min intervals with repeated processing using a second batch of oil. Six replicates of GC-FID fatty acid analysis were conducted for each oil sample. The oil samples were scanned using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and the spectrum was collected. Calibration models were developed using partial least-squares (PLS-1) regression using Unscrambler software. Models were validated using a full cross-validation technique and tested using samples that were not included in the calibration sample set. Measured and predicted total CLA, trans,trans CLA isomers, total mono trans CLA isomers, trans-10,cis-12 CLA, trans-9,cis-11 CLA and cis-10,trans-12 CLA, and cis-9,trans-11 CLA had cross-validated coefficients of determinations (R2v) of 0.97, 0.98, 0.97, 0.98, 0.97, and 0.99 and corresponding root-mean-square error of validation (RMSEV) of 1.14, 0.69, 0.27, 0.07, 0.14, and 0.07% CLA, respectively. The ATR-FTIR technique is a rapid and less expensive method for determining CLA isomers in linoleic acid photo-isomerized soy oil than GC-FID.

Line defects on As2Se3-Chalcogenide photonic crystals for the design of all-optical power splitters and digital logic gates

NASA Astrophysics Data System (ADS)

Saghaei, Hamed; Zahedi, Abdulhamid; Karimzadeh, Rouhollah; Parandin, Fariborz

2017-10-01

In this paper, a triangular two-dimensional photonic crystal (PhC) of As2Se3-chalcogenide rods in air is presented and its photonic band diagram is calculated by plane wave method. In this structure, an optical waveguide is obtained by creating a line defect (eliminating rods) in diagonal direction of PhC. Numerical simulations based on finite difference time domain method show that when self-collimated beams undergo total internal reflection at the PhC-air interface, a total reflection of 90° occurs for the output beams. We also demonstrate that by decreasing the radius of As2Se3-chalcogenide instead of eliminating a diagonal line, a two-channel optical splitter will be designed. In this case, incoming self-collimated beams can be divided into the reflected and transmitted beams with arbitrary power ratio by adjusting the value of their radii. Based on these results, we propose a four-channel optical splitter using four line defects. The power ratio among output channels can be controlled systematically by varying the radius of rods in the line defects. We also demonstrate that by launching two optical sources with the same intensity and 90° phase difference from both perpendicular faces of the PhC, two logic OR and XOR gates will be achieved at the output channels. These optical devices have some applications in photonic integrated circuits for controlling and steering (managing) the light as desired.

Publications - GMC 30 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 30 Publication Details Title: Geochemical analysis (total organic carbon, rock-eval pyrolysis , Geochemical analysis (total organic carbon, rock-eval pyrolysis, vitrinite reflectance and gc/ms chromato (1.3 M) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon; Vitrinite Reflectance Top of

Publications - GMC 207 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 207 Publication Details Title: Total organic carbon, rock-eval, and vitrinite reflectance data for more information. Bibliographic Reference Unknown, 1993, Total organic carbon, rock-eval, and Report Information gmc207.pdf (165.0 K) Keywords Total Organic Carbon; Vitrinite Reflectance Top of Page

Publications - GMC 60 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 60 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite , Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance geochemical data for the Nechelik (125.0 K) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon; Vitrinite Reflectance Top of

Publications - GMC 62 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 62 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite . Bibliographic Reference Unknown, 1985, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance Pyrolysis; Total Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources, Division

Publications - GMC 286 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 286 Publication Details Title: Total organic carbon (TOC), rock-eval, vitrinite reflectance publication sales page for more information. Bibliographic Reference DGSI, Inc., 1999, Total organic carbon Products Report Report Information gmc286.pdf (2.0 M) Keywords Total Organic Carbon; Vitrinite Reflectance

Publications - GMC 59 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 59 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite . Bibliographic Reference Unknown, 1985, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance -Eval Pyrolysis; Total Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources

The Use of ATR-FTIR in Conjunction with Thermal Analysis Methods for Efficient Identification of Polymer Samples: A Qualitative Multiinstrument Instrumental Analysis Laboratory Experiment

ERIC Educational Resources Information Center

Dickson-Karn, Nicole M.

2017-01-01

A multi-instrument approach has been applied to the efficient identification of polymers in an upper-division undergraduate instrumental analysis laboratory course. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) is used in conjunction with differential scanning calorimetry (DSC) to identify 18 polymer samples and…

Simultaneous multicolor detection system of the single-molecular microbial antigen by total internal reflection fluorescence microscopy with fluorescent nanocrystal quantum dots

NASA Astrophysics Data System (ADS)

Hoshino, Akiyoshi; Fujioka, Kouki; Yamamoto, Mayu; Manabe, Noriyoshi; Yasuhara, Masato; Suzuki, Kazuo; Yamamoto, Kenji

2005-11-01

Immunological diagnostic methods have been widely performed and showed high performance in molecular and cellular biology, molecular imaging, and medical diagnostics. We have developed novel methods for the fluorescent labeling of several antibodies coupled with fluorescent nanocrystals QDs. In this study we demonstrated that two bacterial toxins, diphtheria toxin and tetanus toxin, were detected simultaneously in the same view field of a cover slip by using directly QD-conjugated antibodies. We have succeeded in detecting bacterial toxins by counting luminescent spots on the evanescent field with using primary antibody conjugated to QDs. In addition, each bacterial toxin in the mixture can be separately detected by single excitation laser with emission band pass filters, and simultaneously in situ pathogen quantification was performed by calculating the luminescent density on the surface of the cover slip. Our results demonstrate that total internal reflection fluorescence microscopy (TIRFM) enables us to distinguish each antigen from mixed samples and can simultaneously quantitate multiple antigens by QD-conjugated antibodies. Bioconjugated QDs could have great potentialities for in practical biomedical applications to develop various high-sensitivity detection systems.

Fabrication of spherical mitigation pit on KH2PO4 crystal by micro-milling and modeling of its induced light intensification.

PubMed

Cheng, Jian; Chen, Mingjun; Liao, Wei; Wang, Haijun; Xiao, Yong; Li, Mingquan

2013-07-15

Micro-machining is the most promising method for KH(2)PO(4) crystal to mitigate the surface damage growth in high power laser system. In this work, spherical mitigation pit is fabricated by micro-milling with an efficient machining procedure. The light intensification caused by rear surface features before and after mitigation is numerically modeled based on the finite-difference time-domain method. The results indicate that the occurrence of total internal reflections should be responsible for the largest light intensification inside the crystal. For spherical pits after mitigation, the light intensification can be greatly alleviated by preventing the occurrence of total internal reflections. The light intensification caused by spherical mitigation pit is strongly dependent on the width-depth ratio and it is suggested that the width-depth ratio of spherical mitigation pit must be devised to be larger than 5.0 to achieve the minimal light intensification for the mitigation of surface damage growth. Laser damage tests for KH(2)PO(4) crystal validate that the laser damage resistance of initially damaged surface can be retrieved to near the level of ideal surface by replacing initial damage site with predesigned mitigation pit.

Improvement of Electropolishing of 1100 Al Alloy for Solar Thermal Applications

NASA Astrophysics Data System (ADS)

Aguilar-Sierra, Sara María; Echeverría E, Félix

2018-03-01

Aluminum sheets-based mirrors are finding applicability in high-temperature solar concentrating technologies because they are cost-effective, lightweight and have high mechanical properties. Nonetheless, the reflectance percentages obtained by electropolishing are not close to the reflectance values of the currently used evaporated films. Therefore, controlling key factors affecting electropolishing processes became essential in order to achieve highly reflective aluminum surfaces. This study investigated the effect of both the electropolishing process and previous heat treatment on the total reflectance of the AA 1100 aluminum alloy. An acid electrolyte and a modified Brytal process were evaluated. Total reflectance was measured by means of UV-Vis spectrophotometry. Reflectance values higher than 80% at 600 nm were achieved for both electrolytes. Optical microscopy and scanning electron microscopy images showed uneven dissolution for the acid electropolished samples causing a reflectance drop in the 200-450 nm region. The influence of heat treatment, previously to electropolishing, was tested at two different temperatures and various holding times. It was found that reflectance increases around 15% for the heat-treated and electropolished samples versus the non-heat-treated ones. A heat treatment at low temperature combined with a short holding time was enough to improve the sample total reflectance.

Directional impulse response of a large cavity inside a sonic crystal.

PubMed

Spiousas, Ignacio; Eguia, Manuel C

2012-10-01

Both temporal and directional responses of a cavity inside a two-dimensional sonic crystal are investigated. The size of the cavity is large compared to the lattice parameter and the wavelength for the frequency range of interest. Hence, a hybrid method to compute the response is proposed, combining multiscattering theory for the calculation of the reflective properties of the sonic crystal with a modified ray-tracing algorithm for the sound propagation within the cavity. The response of this enclosure displays resonances for certain frequency bands that depend on the geometry of the lattice and the cavity. When a full band gap exists in the sonic crystal, rays cannot propagate through the medium and total reflection occurs for all incidence angles, leading to strong resonances with an isotropic intensity field inside the cavity. When only some propagation directions are forbidden, total reflection occurs for certain ranges of incidence angles, and resonances can also be elicited but with a highly anisotropic intensity field. The spectrum of resonances of the cavity is strongly affected by changes in the lattice geometry, suggesting that they can be tailored to some extent, a feature that can lead to potential applications in architectural acoustics.

The use of visible-channel data from NOAA satellites to measure total ozone amount over Antarctica

NASA Technical Reports Server (NTRS)

Boime, Robert D.; Warren, Steven G.; Gruber, Arnold

1994-01-01

Accurate, detailed maps of total ozone were not available until the launch of the Total Ozone Mapping Spectrometer (TOMS) in late 1978. However, the Scanning Radiometer (SR), an instrument on board the NOAA series satellites during the 1970s, had a visible channel that overlapped closely with the Chappuis absorption band of ozone. We are investigating whether data from the SR can be used to map Antarctic ozone prior to 1978. The method is being developed with 1980s data from the Advanced Very High Resolution Radiometer (AVHRR), which succeeded the SR on the NOAA polar-orbiting satellites. Visible-derived total ozone maps can then be compared able on the NOAA satellites, which precludes the use of a differential absorption technique to measure ozone. Consequently, our method works exclusively over scenes whose albedos are large and unvarying, i.e. scenes that contain ice sheets and/or uniform cloud-cover. Initial comparisons of time series for October-December 1987 at locations in East Antarctica show that the visible absorption by ozone in measurable and that the technique may be usable for the 1970s, but with much less accuracy than TOMS. This initial test assumes that clouds, snow, and ice all reflect the same percentage of visible light towards the satellite, regardless of satellite position or environmental conditions. This assumption is our greatest source of error. To improve the accuracy of ozone retrievals, realistic anisotropic reflectance factors are needed, which are strongly influenced by cloud and snow surface features.

A second-order accurate kinetic-theory-based method for inviscid compressible flows

NASA Technical Reports Server (NTRS)

Deshpande, Suresh M.

1986-01-01

An upwind method for the numerical solution of the Euler equations is presented. This method, called the kinetic numerical method (KNM), is based on the fact that the Euler equations are moments of the Boltzmann equation of the kinetic theory of gases when the distribution function is Maxwellian. The KNM consists of two phases, the convection phase and the collision phase. The method is unconditionally stable and explicit. It is highly vectorizable and can be easily made total variation diminishing for the distribution function by a suitable choice of the interpolation strategy. The method is applied to a one-dimensional shock-propagation problem and to a two-dimensional shock-reflection problem.

DESIGN NOTE: New apparatus for haze measurement for transparent media

NASA Astrophysics Data System (ADS)

Yu, H. L.; Hsiao, C. C.; Liu, W. C.

2006-08-01

Precise measurement of luminous transmittance and haze of transparent media is increasingly important to the LCD industry. Currently there are at least three documentary standards for measuring transmission haze. Unfortunately, none of those standard methods by itself can obtain the precise values for the diffuse transmittance (DT), total transmittance (TT) and haze. This note presents a new apparatus capable of precisely measuring all three variables simultaneously. Compared with current structures, the proposed design contains one more compensatory port. For optimal design, the light trap absorbs the beam completely, light scattered by the instrument is zero and the interior surface of the integrating sphere, baffle, as well as the reflectance standard, are of equal characteristic. The accurate values of the TT, DT and haze can be obtained using the new apparatus. Even if the design is not optimal, the measurement errors of the new apparatus are smaller than those of other methods especially for high sphere reflectance. Therefore, the sphere can be made of a high reflectance material for the new apparatus to increase the signal-to-noise ratio.

Sensitive radioimmunoassay of total thyroxine (T4) in horses using a simple extraction method.

PubMed

Tangyuenyong, Siriwan; Nambo, Yasuo; Nagaoka, Kentaro; Tanaka, Tomomi; Watanabe, Gen

2017-07-28

Most thyroid hormone determinations in animals are based on immunoassays adapted from those used to test human samples, which may not reflect the actual values of thyroid hormone in horses because of the presence of binding proteins. The aims of the present study were i) to establish a novel radioimmunoassay (RIA) using a more simple and convenient method to separate binding proteins for the measurement of total thyroxine (T4) in horses and ii) to validate the assay by comparing total T4 concentrations in yearling horses raised in different climates. Blood samples were collected from trained yearlings in Hokkaido (temperate climate) and Miyazaki (subtropical climate) in Japan and from adult horses in estrus and diestrus. T4 was extracted from both serum and plasma using modified acid ethanol cryo-precipitation and sodium acetate ethanol methods. Circulating total T4 concentrations were determined by RIA. T4 concentration by sodium acetate ethanol was appropriately detectable rather than sodium salicylate method and was the same as for acid ethanol method. Furthermore, this sodium acetate ethanol method required fewer extraction steps than the other methods. Circulating T4 concentrations in yearlings were 225.98 ± 20.89 ng/ml, which was higher than the previous reference values. With respect to climate, T4 levels in Hokkaido yearlings tended to be higher than those in Miyazaki yearlings throughout the study period. These results indicated that this RIA protocol using a modified sodium acetate ethanol separation technique might be an appropriate tool for specific measurement of total T4 in horses.

Electrowetting-actuated optical switch based on total internal reflection.

PubMed

Liu, Chao; Wang, Di; Yao, Li-Xiao; Li, Lei; Wang, Qiong-Hua

2015-04-01

In this paper we demonstrate a liquid optical switch based on total internal reflection. Two indium tin oxide electrodes are fabricated on the bottom substrate. A conductive liquid (Liquid 1) is placed on one side of the chamber and surrounded by a density-matched silicone oil (Liquid 2). In initial state, when the light beam illuminates the interface of the two liquids, it just meets the conditions of total internal reflection. The light is totally reflected by Liquid 2, and the device shows light-off state. When we apply a voltage to the other side of the indium tin oxide electrode, Liquid 1 stretched towards this side of the substrate and the curvature of the liquid-liquid interface changes. The light beam is refracted by Liquid 1 and the device shows light-on state. So the device can achieve the functions of an optical switch. Because the light beam can be totally reflected by the liquid, the device can attain 100% light intensity attenuation. Our experiments show that the response time from light-on (off) to light-off (on) are 130 and 132 ms, respectively. The proposed optical switch has potential applications in variable optical attenuators, information displays, and light shutters.

Centrifugal ultrafiltration of human serum for improving immunoglobulin A quantification using attenuated total reflectance infrared spectroscopy.

PubMed

Elsohaby, Ibrahim; McClure, J Trenton; Riley, Christopher B; Bryanton, Janet; Bigsby, Kathryn; Shaw, R Anthony

2018-02-20

Attenuated total reflectance infrared (ATR-IR) spectroscopy is a simple, rapid and cost-effective method for the analysis of serum. However, the complex nature of serum remains a limiting factor to the reliability of this method. We investigated the benefits of coupling the centrifugal ultrafiltration with ATR-IR spectroscopy for quantification of human serum IgA concentration. Human serum samples (n = 196) were analyzed for IgA using an immunoturbidimetric assay. ATR-IR spectra were acquired for whole serum samples and for the retentate (residue) reconstituted with saline following 300 kDa centrifugal ultrafiltration. IR-based analytical methods were developed for each of the two spectroscopic datasets, and the accuracy of each of the two methods compared. Analytical methods were based upon partial least squares regression (PLSR) calibration models - one with 5-PLS factors (for whole serum) and the second with 9-PLS factors (for the reconstituted retentate). Comparison of the two sets of IR-based analytical results to reference IgA values revealed improvements in the Pearson correlation coefficient (from 0.66 to 0.76), and the root mean squared error of prediction in IR-based IgA concentrations (from 102 to 79 mg/dL) for the ultrafiltration retentate-based method as compared to the method built upon whole serum spectra. Depleting human serum low molecular weight proteins using a 300 kDa centrifugal filter thus enhances the accuracy IgA quantification by ATR-IR spectroscopy. Further evaluation and optimization of this general approach may ultimately lead to routine analysis of a range of high molecular-weight analytical targets that are otherwise unsuitable for IR-based analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

A comparative review of optical surface contamination assessment techniques

NASA Technical Reports Server (NTRS)

Heaney, James B.

1987-01-01

This paper will review the relative sensitivities and practicalities of the common surface analytical methods that are used to detect and identify unwelcome adsorbants on optical surfaces. The compared methods include visual inspection, simple reflectometry and transmissiometry, ellipsometry, infrared absorption and attenuated total reflectance spectroscopy (ATR), Auger electron spectroscopy (AES), scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS), and mass accretion determined by quartz crystal microbalance (QCM). The discussion is biased toward those methods that apply optical thin film analytical techniques to spacecraft optical contamination problems. Examples are cited from both ground based and in-orbit experiments.

Drugs of abuse detection in saliva based on actuated optical method

NASA Astrophysics Data System (ADS)

Shao, Jie; Li, Zhenyu; Jiang, Hong; Wang, Wenlong; Wu, Yixuan

2014-12-01

There has been a considerable increase in the abuse of drugs during the past decade. Combing drug use with driving is very dangerous. More than 11% of drivers in a roadside survey tested positive for drugs, while 18% of drivers killed in accidents tested positive for drugs as reported in USA, 2007. Toward developing a rapid drug screening device, we use saliva as the sample, and combining the traditional immunoassays method with optical magnetic technology. There were several methods for magnetic nanoparticles detection, such as magnetic coils, SQUID, microscopic imaging, and Hall sensors. All of these methods were not suitable for our demands. By developing a novel optical scheme, we demonstrate high-sensitivity detection in saliva. Drugs of abuse are detected at sub-nano gram per milliliter levels in less than 120 seconds. Evanescent wave principle has been applied to sensitively monitor the presence of magnetic nanoparticles on the binding surface. Like the total internal reflection fluorescence microscope (TIRFM), evanescent optical field is generated at the plastic/fluid interface, which decays exponentially and penetrates into the fluid by only a sub-wavelength distance. By disturbance total internal reflection with magnetic nanoparticles, the optical intensity would be influenced. We then detected optical output by imaging the sensor surface onto a CCD camera. We tested four drugs tetrahydrocannabinol (THC), methamphetamine (MAMP), ketamine (KET), morphine (OPI), using this technology. 100 ng mL-1 sensitivity was achieved, and obvious evidence showed that this results could be improved in further researches.

A Characterization of Student Reflections in an Introductory Pharmacy Practice Experience Discussion Course.

PubMed

Dinkins, Melissa M; Haltom, Wesley R

2018-04-01

Objective. To characterize weekly student reflections in an introductory pharmacy practice experience (IPPE) discussion course meeting concurrently with IPPE rotations in institutional pharmacy. Methods. A qualitative analysis was conducted to identify themes within weekly reflective statements submitted by second year pharmacy students (P2) enrolled in an IPPE rotation and concurrent discussion course. Weekly reflections from the 2015-2016 offering of the course were reviewed by investigators to identify common themes via an iterative process. Subsequently, investigators coded each submission into one of the identified categories. Initial agreement between investigators was assessed using the Cohen kappa coefficient. Discrepancies between coding were resolved through discussion to reach consensus. Results. A total of 402 reflection assignments were reviewed from 85 P2 students enrolled in the IPPE course. Ten themes were identified, with the most common themes being interprofessional teamwork, pharmacist and technician roles and responsibilities, and policies and procedures. Substantial initial agreement between investigators was found, with the most discrepancies arising within the themes of medication distribution and pharmacy administration/organizational structure. Conclusion. Student reflections on IPPEs centered on 10 key topics, primarily related to distributive, legal, and regulatory functions of institutional pharmacy practice. Structuring an IPPE rotation longitudinally in an academic term, with a concurrent discussion course, builds a framework for regular student reflection.

Microscale Solubility Measurements of Matrix-Assisted Laser Desorption-Ionization (MALDI) Matrices Using Attenuated Total Reflection (ATR) Fourier Transform Infrared Spectroscopy (FT-IR) Coupled with Partial Least Squares (PLS) Analysis.

PubMed

Gorre, Elsa; Owens, Kevin G

2016-11-01

In this work an attenuated total reflection Fourier transform infrared (FT-IR) absorption based method is used to measure the solubility of two matrix-assisted laser desorption-ionization (MALDI) matrices in a few pure solvents and mixtures of acetonitrile and water using low microliter amounts of solution. Results from a method that averages the values obtained from multiple calibration curves created by manual peak picking are compared to those predicted using a partial least squares (PLS) chemometrics approach. The PLS method provided solubility values that were in good agreement with the manual method with significantly greater ease of analysis. As a test, the solubility of adipic acid in acetone was measured using the two methods of analysis, and the values are in good agreement with solubility values reported in literature. The solubilities of the MALDI matrices α-cyano-4-hydroxy cinnamic acid (CHCA) and sinapinic acid (SA) were measured in a series of mixtures made from acetonitrile (ACN) and water; surprisingly, the results show a highly nonlinear trend. While both CHCA and SA show solubility values of less than 10 mg/mL in the pure solvents, the solubility value for SA increases to 56.3 mg/mL in a 75:25 v/v ACN:water mixture. This can have a significant effect on the matrix-to-analyte ratios in the MALDI experiment when sample protocols call for preparation of a saturated solution of the matrix in the chosen solvent system. © The Author(s) 2016.

Full-wave reflection of lightning long-wave radio pulses from the ionospheric D region: Comparison with midday observations of broadband lightning signals

NASA Astrophysics Data System (ADS)

Jacobson, Abram R.; Shao, Xuan-Min; Holzworth, Robert

2010-05-01

We are developing and testing a steep-incidence D region sounding method for inferring profile information, principally regarding electron density. The method uses lightning emissions (in the band 5-500 kHz) as the probe signal. The data are interpreted by comparison against a newly developed single-reflection model of the radio wave's encounter with the lower ionosphere. The ultimate application of the method will be to study transient, localized disturbances of the nocturnal D region, including those instigated by lightning itself. Prior to applying the method to study lightning-induced perturbations of the nighttime D region, we have performed a validation test against more stable and predictable daytime observations, where the profile of electron density is largely determined by direct solar X-ray illumination. This article reports on the validation test. Predictions from our recently developed full-wave ionospheric-reflection model are compared to statistical summaries of daytime lightning radiated waveforms, recorded by the Los Alamos Sferic Array. The comparison is used to retrieve best fit parameters for an exponential profile of electron density in the ionospheric D region. The optimum parameter values are compared to those found elsewhere using a narrowband beacon technique, which used totally different measurements, ranges, and modeling approaches from those of the work reported here.

Multi-Resolution Analysis of MODIS and ASTER Satellite Data for Water Classification

DTIC Science & Technology

2006-09-01

spectral bands, but also with different pixel resolutions . The overall goal... the total water surface. Due to the constraint that high spatial resolution satellite images are low temporal resolution , one needs a reliable method...at 15 m resolution , were processed. We used MODIS reflectance data from MOD02 Level 1B data. Even the spatial resolution of the 1240 nm

Determination of fluorine by total reflection X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Tarsoly, G.; Óvári, M.; Záray, Gy.

2010-04-01

There is a growing interest in determination of low Z elements, i.e. carbon to phosphorus, in various samples. Total reflection X-ray fluorescence spectrometry (TXRF) has been already established as a suitable trace element analytical method with low sample demand and quite good quantification limits. Recently, the determinable element range was extended towards Z = 6 (carbon). In this study, the analytical performance of the total reflection X-ray fluorescence spectrometry for determination of fluorine was investigated applying a spectrometer equipped with Cr-anode X-ray tube, multilayer monochromator, vacuum chamber, and a silicon drift detector (SDD) with ultra thin window was used. The detection limit for fluorine was found to be 5 mg L - 1 (equivalent to 10 ng absolute) in aqueous matrix. The linear range of the fluorine determination is between 15 and 500 mg L - 1 , within this range the precision is below 10%. The matrix effects of the other halogens (chlorine, bromine and iodine), and sulfate were also investigated. It has been established that the upper allowed concentration limit of the above interfering elements is 100, 200, 50 and 100 mg L - 1 for Cl, Br, I and sulfate, respectively. Moreover, the role of the pre-siliconization of the quartz carrier plate was investigated. It was found, that the presence of the silicone results in poorer analytical performance, which can be explained by the thicker sample residue and stronger self-absorption of the fluorescent radiation.

Frustrated total internal reflection acoustic field sensor

DOEpatents

Kallman, Jeffrey S.

2000-01-01

A frustrated total internal reflection acoustic field sensor which allows the acquisition of the acoustic field over an entire plane, all at once. The sensor finds use in acoustic holography and acoustic diffraction tomography. For example, the sensor may be produced by a transparent plate with transparent support members tall enough to support one or more flexible membranes at an appropriate height for frustrated total internal reflection to occur. An acoustic wave causes the membrane to deflect away from its quiescent position and thus changes the amount of light that tunnels through the gap formed by the support members and into the membrane, and so changes the amount of light reflected by the membrane. The sensor(s) is illuminated by a uniform tight field, and the reflection from the sensor yields acoustic wave amplitude and phase information which can be picked up electronically or otherwise.

Reflection of a TE-polarised Gaussian beam from a layered structure under conditions of resonance excitation of waveguide modes

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

Sokolov, V I; Marusin, N V; Molchanova, S I

2014-11-30

The problem of reflection of a TE-polarised Gaussian light beam from a layered structure under conditions of resonance excitation of waveguide modes using a total internal reflection prism is considered. Using the spectral approach we have derived the analytic expressions for the mode propagation lengths, widths and depths of m-lines (sharp and narrow dips in the angular dependence of the specular reflection coefficient), depending on the structure parameters. It is shown that in the case of weak coupling, when the propagation lengths l{sub m} of the waveguide modes are mainly determined by the extinction coefficient in the film, the depthmore » of m-lines grows with the mode number m. In the case of strong coupling, when l{sub m} is determined mainly by the radiation of modes into the prism, the depth of m-lines decreases with increasing m. The change in the TE-polarised Gaussian beam shape after its reflection from the layered structure is studied, which is determined by the energy transfer from the incident beam into waveguide modes that propagate along the structure by the distance l{sub m}, are radiated in the direction of specular reflection and interfere with a part of the beam reflected from the working face of the prism. It is shown that this interference can lead to the field intensity oscillations near m-lines. The analysis of different methods for determining the parameters of thin-film structures is presented, including the measurement of mode angles θ{sub m} and the reflected beam shape. The methods are based on simultaneous excitation of a few waveguide modes in the film with a strongly focused monochromatic Gaussian beam, the waist width of which is much smaller than the propagation length of the modes. As an example of using these methods, the refractive index and the thickness of silicon monoxide film on silica substrate at the wavelength 633 nm are determined. (fibre and integrated-optical structures)« less

Recent advances in mid- and near-infrared spectroscopy with applications for research and teaching, focusing on petrochemistry and biotechnology relevant products

NASA Astrophysics Data System (ADS)

Heise, H. M.; Fritzsche, J.; Tkatsch, H.; Waag, F.; Karch, K.; Henze, K.; Delbeck, S.; Budde, J.

2013-11-01

Mid- and near-infrared spectroscopy is introduced as a versatile analytical method for characterizing liquid and solid chemicals as obtained from petrochemistry and biotechnology processes. Besides normal transmission measurements, special equipment with silver halide fiber-optic probes allowing efficient analysis based on mid-infrared attenuated total reflection, and an accessory for near-infrared diffuse reflection measurements, are presented. The latter technique can be used advantageously for powdered samples such as microalgae biomass and polysaccharides, as well as for different tissues such as meat samples. The advantages and disadvantages of both methods, which can be used for industrial process monitoring and chemical quality control applications, are discussed, and have been used in several research projects of BSc students within their degree course of bio- and nano-technologies of our University of Applied Sciences.

Generating a Generation of Proteasome Inhibitors: From Microbial Fermentation to Total Synthesis of Salinosporamide A (Marizomib) and Other Salinosporamides

PubMed Central

Potts, Barbara C.; Lam, Kin S.

2010-01-01

The salinosporamides are potent proteasome inhibitors among which the parent marine-derived natural product salinosporamide A (marizomib; NPI-0052; 1) is currently in clinical trials for the treatment of various cancers. Methods to generate this class of compounds include fermentation and natural products chemistry, precursor-directed biosynthesis, mutasynthesis, semi-synthesis, and total synthesis. The end products range from biochemical tools for probing mechanism of action to clinical trials materials; in turn, the considerable efforts to produce the target molecules have expanded the technologies used to generate them. Here, the full complement of methods is reviewed, reflecting remarkable contributions from scientists of various disciplines over a period of 7 years since the first publication of the structure of 1. PMID:20479958

Direct determination of sorbitol and sodium glutamate by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) in the thermostabilizer employed in the production of yellow-fever vaccine.

PubMed

de Castro, Eduardo da S G; Cassella, Ricardo J

2016-05-15

Reference methods for quality control of vaccines usually require treatment of the samples before analysis. These procedures are expensive, time-consuming, unhealthy and require careful manipulation of the sample, making them a potential source of analytical errors. This work proposes a novel method for the quality control of thermostabilizer samples of the yellow fever vaccine employing attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR). The main advantage of the proposed method is the possibility of direct determination of the analytes (sodium glutamate and sorbitol) without any pretreatment of the samples. Operational parameters of the FTIR technique, such as the number of accumulated scans and nominal resolution, were evaluated. The best conditions for sodium glutamate were achieved when 64 scans were accumulated using a nominal resolution of 4 cm(-1). The measurements for sodium glutamate were performed at 1347 cm(-1) (baseline correction between 1322 and 1369 cm(-1)). In the case of sorbitol, the measurements were done at 890cm(-1) (baseline correction between 825 and 910 cm(-1)) using a nominal resolution of 2 cm(-1) with 32 accumulated scans. In both cases, the quantitative variable was the band height. Recovery tests were performed in order to evaluate the accuracy of the method and recovery percentages in the range 93-106% were obtained. Also, the methods were compared with reference methods and no statistical differences were observed. The limits of detection and quantification for sodium glutamate were 0.20 and 0.62% (m/v), respectively, whereas for sorbitol they were 1 and 3.3% (m/v), respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

ATR-FTIR membrane-based sensor for the simultaneous determination of surfactant and oil total indices in industrial degreasing baths.

PubMed

Lucena, Rafael; Cárdenas, Soledad; Gallego, Mercedes; Valcárcel, Miguel

2006-03-01

Monitoring the exhaustion of alkaline degreasing baths is one of the main aspects in metal mechanizing industrial process control. The global level of surfactant, and mainly grease, can be used as ageing indicators. In this paper, an attenuated total reflection-Fourier transform infrared (ATR-FTIR) membrane-based sensor is presented for the determination of these parameters. The system is based on a micro-liquid-liquid extraction of the analytes through a polymeric membrane from the aqueous to the organic solvent layer which is in close contact with the internal reflection element and continuously monitored. Samples are automatically processed using a simple, robust sequential injection analysis (SIA) configuration, on-line coupled to the instrument. The global signal obtained for both families of compounds are processed via a multivariate calibration technique (partial least squares, PLS). Excellent correlation was obtained for the values given by the proposed method compared to those of the gravimetric reference one with very low error values for both calibration and validation.

Real time study of amalgam formation and mercury adsorption on thin gold film by total internal reflection ellipsometry

NASA Astrophysics Data System (ADS)

Paulauskas, A.; Selskis, A.; Bukauskas, V.; Vaicikauskas, V.; Ramanavicius, A.; Balevicius, Z.

2018-01-01

Total internal reflection ellipsometry (TIRE) was utilized in its dynamic data acquisition mode to reveal the percentage of mercury present in an amalgam surface layer. In determining the optical constants of the amalgam film, the non-homogeneities of the formed surface layer were taken into account. The composition of the amalgam layer by percentage was determined using the EMA Bruggemann model for the analysis of the TIRE data. Regression results showed that amalgam layer consisted of mercury 16.00 ± 0.43% and gold 84.00 ± 0.43%. This real time TIRE analysis has shown that for these studies method can detect 0.6 ± 0.4% of mercury on a gold surface, proving that this is a suitable optical technique for obtaining real time readouts. The structural analysis of SEM and AFM have shown that the amalgam layer had a dendritic structure, which formation was determined by the weak adhesion of the gold atoms onto its surface.

Identification of trace additives in polymer materials by attenuated total reflection Fourier transform infrared mapping coupled with multivariate curve resolution

NASA Astrophysics Data System (ADS)

Li, Qian; Tang, Yongjiao; Yan, Zhiwei; Zhang, Pudun

2017-06-01

Although multivariate curve resolution (MCR) has been applied to the analysis of Fourier transform infrared (FTIR) imaging, it is still problematic to determine the number of components. The reported methods at present tend to cause the components of low concentration missed. In this paper a new idea was proposed to resolve this problem. First, MCR calculation was repeated by increasing the number of components sequentially, then each retrieved pure spectrum of as-resulted MCR component was directly compared with a real-world pixel spectrum of the local high concentration in the corresponding MCR map. One component was affirmed only if the characteristic bands of the MCR component had been included in its pixel spectrum. This idea was applied to attenuated total reflection (ATR)/FTIR mapping for identifying the trace additives in blind polymer materials and satisfactory results were acquired. The successful demonstration of this novel approach opens up new possibilities for analyzing additives in polymer materials.

Design and Construction of a Multi-wavelength, Micromirror Total Internal Reflectance Fluorescence Microscope

PubMed Central

Larson, Joshua; Kirk, Matt; Drier, Eric A.; O’Brien, William; MacKay, James F.; Friedman, Larry; Hoskins, Aaron

2015-01-01

Colocalization Single Molecule Spectroscopy (CoSMoS) has proven to be a useful method for studying the composition, kinetics, and mechanisms of complex cellular machines. Key to the technique is the ability to simultaneously monitor multiple proteins and/or nucleic acids as they interact with one another. Here we describe a protocol for constructing a CoSMoS micromirror Total Internal Reflection Fluorescence Microscope (mmTIRFM). Design and construction of a scientific microscope often requires a number of custom components and a significant time commitment. In our protocol, we have streamlined this process by implementation of a commercially available microscopy platform designed to accommodate the optical components necessary for a mmTIRFM. The mmTIRF system eliminates the need for machining custom parts by the end-user and facilitates optical alignment. Depending on the experience-level of the microscope builder, these time-savings and the following protocol can enable mmTIRF construction to be completed within two months. PMID:25188633

Design and construction of a multiwavelength, micromirror total internal reflectance fluorescence microscope.

PubMed

Larson, Joshua; Kirk, Matt; Drier, Eric A; O'Brien, William; MacKay, James F; Friedman, Larry J; Hoskins, Aaron A

2014-10-01

Colocalization single-molecule spectroscopy (CoSMoS) has proven to be a useful method for studying the composition, kinetics and mechanisms of complex cellular machines. Key to the technique is the ability to simultaneously monitor multiple proteins and/or nucleic acids as they interact with one another. Here we describe a protocol for constructing a CoSMoS micromirror total internal reflection fluorescence microscope (mmTIRFM). Design and construction of a scientific microscope often requires a number of custom components and a substantial time commitment. In our protocol, we have streamlined this process by implementation of a commercially available microscopy platform designed to accommodate the optical components necessary for an mmTIRFM. The mmTIRF system eliminates the need for machining custom parts by the end user and facilitates optical alignment. Depending on the experience level of the microscope builder, these time savings and the following protocol can enable mmTIRF construction to be completed within 2 months.

Classification of pumpkin seed oils according to their species and genetic variety by attenuated total reflection Fourier-transform infrared spectroscopy.

PubMed

Saucedo-Hernández, Yanelis; Lerma-García, María Jesús; Herrero-Martínez, José Manuel; Ramis-Ramos, Guillermo; Jorge-Rodríguez, Elisa; Simí-Alfonso, Ernesto F

2011-04-27

Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), followed by multivariate treatment of the spectral data, was used to classify seed oils of the genus Cucurbita (pumpkins) according to their species as C. maxima, C. pepo, and C. moschata. Also, C. moschata seed oils were classified according to their genetic variety as RG, Inivit C-88, and Inivit C-2000. Up to 23 wavelength regions were selected on the spectra, each region corresponding to a peak or shoulder. The normalized absorbance peak areas within these regions were used as predictors. Using linear discriminant analysis (LDA), an excellent resolution among all categories concerning both Cucurbita species and C. moschata varieties was achieved. The proposed method was straightforward and quick and can be easily implemented. Quality control of pumpkin seed oils is important because Cucurbita species and genetic variety are both related to the pharmaceutical properties of the oils.

Minimally invasive screening for colitis using attenuated total internal reflectance Fourier transform infrared spectroscopy

PubMed Central

Titus, Jitto; Viennois, Emilie; Merlin, Didier; Perera, A. G. Unil

2016-01-01

This article describes a rapid, simple and cost-effective technique that could lead to a screening method for colitis without the need for biopsies or in vivo measurements. This screening technique includes the testing of serum using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy for the colitis-induced increased presence of mannose. Chronic (Interleukin 10 knockout) and acute (Dextran Sodium Sulphate-induced) models for colitis are tested using the ATR-FTIR technique. Arthritis (Collagen Antibody Induced Arthritis) and metabolic syndrome (Toll like receptor 5 knockout) models are also tested as controls. The marker identified as mannose uniquely screens and distinguishes the colitic from the non-colitic samples and the controls. The reference or the baseline spectrum could be the pooled and averaged spectra of non-colitic samples or the subject's previous sample spectrum. This shows the potential of having individualized route maps of disease status, leading to personalized diagnosis and drug management. PMID:27094092

Surface Josephson plasma waves in layered superconductors above the plasma frequency: evidence for a negative index of refraction.

PubMed

Golick, V A; Kadygrob, D V; Yampol'skii, V A; Rakhmanov, A L; Ivanov, B A; Nori, Franco

2010-05-07

We predict a new branch of surface Josephson plasma waves (SJPWs) in layered superconductors for frequencies higher than the Josephson plasma frequency. In this frequency range, the permittivity tensor components along and transverse to the layers have different signs, which is usually associated with negative refraction. However, for these frequencies, the bulk Josephson plasma waves cannot be matched with the incident and reflected waves in the vacuum, and, instead of the negative-refractive properties, abnormal surface modes appear within the frequency band expected for bulk modes. We also discuss the excitation of high-frequency SJPWs by means of the attenuated-total-reflection method.

An Analysis Method for Superconducting Resonator Parameter Extraction with Complex Baseline Removal

NASA Technical Reports Server (NTRS)

Cataldo, Giuseppe

2014-01-01

A new semi-empirical model is proposed for extracting the quality (Q) factors of arrays of superconducting microwave kinetic inductance detectors (MKIDs). The determination of the total internal and coupling Q factors enables the computation of the loss in the superconducting transmission lines. The method used allows the simultaneous analysis of multiple interacting discrete resonators with the presence of a complex spectral baseline arising from reflections in the system. The baseline removal allows an unbiased estimate of the device response as measured in a cryogenic instrumentation setting.

Development and application of variable angle internal reflection Raman spectroscopy for vibrationally specific depth-profiling of polymer thin films

NASA Astrophysics Data System (ADS)

Fontaine, Norman Henry

1997-10-01

Techniques which can be used to obtain depth-resolved information on the thermodynamics at polymer-polymer and polymer-wall interfaces, and of small molecule diffusion in polymers, are of particular interest to industry. Optical methods which are sensitive to molecular vibrations (such as internal reflection Raman spectroscopy) are advantageous because they can non- destructively probe molecular content, orientation, and polarity of the local environment in a sample. However, while optical internal reflection depth-profiling methods have been reported, they have never progressed beyond the demonstration stage. In this work, the theory and methodology of internal reflection spectroscopy are developed and optimized into a rigorous field-controlled spectroscopic technique. A novel asymmetric internal reflection element (IRE) is introduced which traps back-reflections, allowing precise evanescent and standing wave probe-field control in the sample for all angles of incidence. It is demonstrated that a Gaussian laser beam will best approximate an infinite homogeneous plane wave when the IRE/sample interface lies in the paraxial-Fraunhofer region (far- field) of the beam path. Calibration methods are presented, sources of systematic errors are identified, and the angular resolution limit (ARL) is introduced as a measure of the field control developed in a sample by any internal reflection method. A general model of Raman scattering and photon detection from multi-layer thin films is developed. A new and generalized operator based transfer matrix method is developed and applied to electromagnetic field and diffusion computations in multi-layer systems. Total internal reflection spectroscopy is extended to include sub-critical angles of incidence, where resonant field enhancements generate large and selective amplification of the probe-field intensity within the layers of the sample. Fitting these resonances to the model spectral intensities allows unique determination of the location of buried interfaces in micron-sized polymer multi-layers with nanometer scale precision and the refractive indices of the layers with precision of /Delta n/approx/pm 0.0001. The Raman active molecular content of each optically distinct layer of the film is determinable simultaneously with the optical properties. Resonant mode VAIRRS studies of poly(methyl methacrylate) films spun-cast from toluene and then dried under ambient conditions have shown evidence for toluene diffusion concurrent with a rotationally hindered relaxation of oriented ester side groups about the polymer backbone. Low temperature annealing (≈87oC) has shown evidence that this hindered rotational relaxation may be reversible. VAIRRS study of a polystyrene/poly(methyl methacrylate) bi-layer has detected evidence for toluene diffusion across the buried polymer-polymer interface.

Application of Multivariable Analysis and FTIR-ATR Spectroscopy to the Prediction of Properties in Campeche Honey

PubMed Central

Pat, Lucio; Ali, Bassam; Guerrero, Armando; Córdova, Atl V.; Garduza, José P.

2016-01-01

Attenuated total reflectance-Fourier transform infrared spectrometry and chemometrics model was used for determination of physicochemical properties (pH, redox potential, free acidity, electrical conductivity, moisture, total soluble solids (TSS), ash, and HMF) in honey samples. The reference values of 189 honey samples of different botanical origin were determined using Association Official Analytical Chemists, (AOAC), 1990; Codex Alimentarius, 2001, International Honey Commission, 2002, methods. Multivariate calibration models were built using partial least squares (PLS) for the measurands studied. The developed models were validated using cross-validation and external validation; several statistical parameters were obtained to determine the robustness of the calibration models: (PCs) optimum number of components principal, (SECV) standard error of cross-validation, (R 2 cal) coefficient of determination of cross-validation, (SEP) standard error of validation, and (R 2 val) coefficient of determination for external validation and coefficient of variation (CV). The prediction accuracy for pH, redox potential, electrical conductivity, moisture, TSS, and ash was good, while for free acidity and HMF it was poor. The results demonstrate that attenuated total reflectance-Fourier transform infrared spectrometry is a valuable, rapid, and nondestructive tool for the quantification of physicochemical properties of honey. PMID:28070445

Scattering of matter waves in spatially inhomogeneous environments

DOE PAGES

Tsitoura, F.; Krüger, P.; Kevrekidis, P. G.; ...

2015-03-30

In this article, we study scattering of quasi-one-dimensional matter waves at an interface of two spatial domains, one with repulsive and one with attractive interatomic interactions. It is shown that the incidence of a Gaussian wave packet from the repulsive to the attractive region gives rise to generation of a soliton train. More specifically, the number of emergent solitons can be controlled, e.g., by the variation of the amplitude or the width of the incoming wave packet. Furthermore, we study the reflectivity of a soliton incident from the attractive region to the repulsive one. We find the reflection coefficient numericallymore » and employ analytical methods, which treat the soliton as a particle (for moderate and large amplitudes) or a quasilinear wave packet (for small amplitudes), to determine the critical soliton momentum (as a function of the soliton amplitude) for which total reflection is observed.« less

Focusing hard x rays beyond the critical angle of total reflection by adiabatically focusing lenses

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

Patommel, Jens; Klare, Susanne; Hoppe, Robert

In response to the conjecture that the numerical aperture of x-ray optics is fundamentally limited by the critical angle of total reflection, the concept of adiabatically focusing refractive lenses was proposed to overcome this limit. Here, we present an experimental realization of these optics made of silicon and demonstrate that they indeed focus 20 keV x rays to a 18.4 nm focus with a numerical aperture of 1.73(9) × 10 –3 that clearly exceeds the critical angle of total reflection of 1.55 mrad.

Focusing hard x rays beyond the critical angle of total reflection by adiabatically focusing lenses

DOE PAGES

Patommel, Jens; Klare, Susanne; Hoppe, Robert; ...

2017-03-06

In response to the conjecture that the numerical aperture of x-ray optics is fundamentally limited by the critical angle of total reflection, the concept of adiabatically focusing refractive lenses was proposed to overcome this limit. Here, we present an experimental realization of these optics made of silicon and demonstrate that they indeed focus 20 keV x rays to a 18.4 nm focus with a numerical aperture of 1.73(9) × 10 –3 that clearly exceeds the critical angle of total reflection of 1.55 mrad.

Broad Band Intra-Cavity Total Reflection Chemical Sensor

DOEpatents

Pipino, Andrew C. R.

1998-11-10

A broadband, ultrahigh-sensitivity chemical sensor is provided that allows etection through utilization of a small, extremely low-loss, monolithic optical cavity. The cavity is fabricated from highly transparent optical material in the shape of a regular polygon with one or more convex facets to form a stable resonator for ray trajectories sustained by total internal reflection. Optical radiation enters and exits the monolithic cavity by photon tunneling in which two totally reflecting surfaces are brought into close proximity. In the presence of absorbing material, the loss per pass is increased since the evanescent waves that exist exterior to the cavity at points where the circulating pulse is totally reflected, are absorbed. The decay rate of an injected pulse is determined by coupling out an infinitesimal fraction of the pulse to produce an intensity-versus-time decay curve. Since the change in the decay rate resulting from absorption is inversely proportional to the magnitude of absorption, a quantitative sensor of concentration or absorption cross-section with 1 part-per-million/pass or better sensitivity is obtained. The broadband nature of total internal reflection permits a single device to be used over a broad wavelength range. The absorption spectrum of the surrounding medium can thereby be obtained as a measurement of inverse decay time as a function of wavelength.

Metal Standards for Waveguide Characterization of Materials

NASA Technical Reports Server (NTRS)

Lambert, Kevin M.; Kory, Carol L.

2009-01-01

Rectangular-waveguide inserts that are made of non-ferromagnetic metals and are sized and shaped to function as notch filters have been conceived as reference standards for use in the rectangular- waveguide method of characterizing materials with respect to such constitutive electromagnetic properties as permittivity and permeability. Such standards are needed for determining the accuracy of measurements used in the method, as described below. In this method, a specimen of a material to be characterized is cut to a prescribed size and shape and inserted in a rectangular- waveguide test fixture, wherein the specimen is irradiated with a known source signal and detectors are used to measure the signals reflected by, and transmitted through, the specimen. Scattering parameters [also known as "S" parameters (S11, S12, S21, and S22)] are computed from ratios between the transmitted and reflected signals and the source signal. Then the permeability and permittivity of the specimen material are derived from the scattering parameters. Theoretically, the technique for calculating the permeability and permittivity from the scattering parameters is exact, but the accuracy of the results depends on the accuracy of the measurements from which the scattering parameters are obtained. To determine whether the measurements are accurate, it is necessary to perform comparable measurements on reference standards, which are essentially specimens that have known scattering parameters. To be most useful, reference standards should provide the full range of scattering-parameter values that can be obtained from material specimens. Specifically, measurements of the backscattering parameter (S11) from no reflection to total reflection and of the forward-transmission parameter (S21) from no transmission to total transmission are needed. A reference standard that functions as a notch (band-stop) filter can satisfy this need because as the signal frequency is varied across the frequency range for which the filter is designed, the scattering parameters vary over the ranges of values between the extremes of total reflection and total transmission. A notch-filter reference standard in the form of a rectangular-waveguide insert that has a size and shape similar to that of a material specimen is advantageous because the measurement configuration used for the reference standard can be the same as that for a material specimen. Typically a specimen is a block of material that fills a waveguide cross-section but occupies only a small fraction of the length of the waveguide. A reference standard of the present type (see figure) is a metal block that fills part of a waveguide cross section and contains a slot, the long dimension of which can be chosen to tailor the notch frequency to a desired value. The scattering parameters and notch frequency can be estimated with high accuracy by use of commercially available electromagnetic-field-simulating software. The block can be fabricated to the requisite precision by wire electrical-discharge machining. In use, the accuracy of measurements is determined by comparison of (1) the scattering parameters calculated from the measurements with (2) the scattering parameters calculated by the aforementioned software.

Review of methodology and technology available for the detection of extrasolar planetary systems

NASA Technical Reports Server (NTRS)

Tarter, J. C.; Black, D. C.; Billingham, J.

1985-01-01

Four approaches exist for the detection of extrasolar planets. According to the only direct method, the planet is imaged at some wavelength in a manner which makes it possible to differentiate its own feeble luminosity (internal energy source plus reflected starlight) from that of the nearby host star. The three indirect methods involve the detection of a planetary mass companion on the basis of the observable effects it has on the host star. A search is conducted regarding the occurrence of regular, periodic changes in the stellar spatial motion (astrometric method) or the velocity of stellar emission line spectra (spectroscopic method) or in the apparent total stellar luminosity (photometric method). Details regarding the approaches employed for implementing the considered methods are discussed.

Application of a new integrated sediment quality assessment method to Huelva estuary and its littoral of influence (Southwestern Spain).

PubMed

Rosado, Daniel; Usero, José; Morillo, José

2015-09-15

A new integrated sediment quality assessment method composed of several assays (particle size profile, total metal content, protease K extraction, total organic carbon, toxicity bioassay with Photobacterium phosphoreum and macrobenthic community alteration) that provides a single result, the environmental degradation index (EDI), has been developed. The new method was tested on the Huelva estuary (southwest of Spain), a highly polluted area where metals dissolved in the water of the Tinto and Odiel rivers precipitate after flowing through the Iberian Pyrite Belt, one of the largest metallogenic areas of massive sulphide deposits in the world. The proposed method satisfactorily was able to reflect different degrees of pollution on the environmental degradation index. Thus, EDI categorized littoral samples as slightly degraded and all the Tinto and some of the Odiel as very highly degraded, emphasizing the lower zone of the Tinto estuary as the most deeply degraded of the entire study area. Copyright © 2015 Elsevier Ltd. All rights reserved.

Detection of Natural Fractures from Observed Surface Seismic Data Based on a Linear-Slip Model

NASA Astrophysics Data System (ADS)

Chen, Huaizhen; Zhang, Guangzhi

2018-03-01

Natural fractures play an important role in migration of hydrocarbon fluids. Based on a rock physics effective model, the linear-slip model, which defines fracture parameters (fracture compliances) for quantitatively characterizing the effects of fractures on rock total compliance, we propose a method to detect natural fractures from observed seismic data via inversion for the fracture compliances. We first derive an approximate PP-wave reflection coefficient in terms of fracture compliances. Using the approximate reflection coefficient, we derive azimuthal elastic impedance as a function of fracture compliances. An inversion method to estimate fracture compliances from seismic data is presented based on a Bayesian framework and azimuthal elastic impedance, which is implemented in a two-step procedure: a least-squares inversion for azimuthal elastic impedance and an iterative inversion for fracture compliances. We apply the inversion method to synthetic and real data to verify its stability and reasonability. Synthetic tests confirm that the method can make a stable estimation of fracture compliances in the case of seismic data containing a moderate signal-to-noise ratio for Gaussian noise, and the test on real data reveals that reasonable fracture compliances are obtained using the proposed method.

Total Internal Reflection Accounts for the Bright Color of the Saharan Silver Ant

PubMed Central

Aron, Serge

2016-01-01

The Saharan silver ant Cataglyphis bombycina is one of the terrestrial living organisms best adapted to tolerate high temperatures. It has recently been shown that the hairs covering the ant’s dorsal body part are responsible for its silvery appearance. The hairs have a triangular cross-section with two corrugated surfaces allowing a high optical reflection in the visible and near-infrared (NIR) range of the spectrum while maximizing heat emissivity in the mid-infrared (MIR). Those two effects account for remarkable thermoregulatory properties, enabling the ant to maintain a lower thermal steady state and to cope with the high temperature of its natural habitat. In this paper, we further investigate how geometrical optical and high reflection properties account for the bright silver color of C. bombycina. Using optical ray-tracing models and attenuated total reflection (ATR) experiments, we show that, for a large range of incidence angles, total internal reflection (TIR) conditions are satisfied on the basal face of each hair for light entering and exiting through its upper faces. The reflection properties of the hairs are further enhanced by the presence of the corrugated surface, giving them an almost total specular reflectance for most incidence angles. We also show that hairs provide an almost 10-fold increase in light reflection, and we confirm experimentally that they are responsible for a lower internal body temperature under incident sunlight. Overall, this study improves our understanding of the optical mechanisms responsible for the silver color of C. bombycina and the remarkable thermoregulatory properties of the hair coat covering the ant’s body. PMID:27073923

An improved method to estimate reflectance parameters for high dynamic range imaging

NASA Astrophysics Data System (ADS)

Li, Shiying; Deguchi, Koichiro; Li, Renfa; Manabe, Yoshitsugu; Chihara, Kunihiro

2008-01-01

Two methods are described to accurately estimate diffuse and specular reflectance parameters for colors, gloss intensity and surface roughness, over the dynamic range of the camera used to capture input images. Neither method needs to segment color areas on an image, or to reconstruct a high dynamic range (HDR) image. The second method improves on the first, bypassing the requirement for specific separation of diffuse and specular reflection components. For the latter method, diffuse and specular reflectance parameters are estimated separately, using the least squares method. Reflection values are initially assumed to be diffuse-only reflection components, and are subjected to the least squares method to estimate diffuse reflectance parameters. Specular reflection components, obtained by subtracting the computed diffuse reflection components from reflection values, are then subjected to a logarithmically transformed equation of the Torrance-Sparrow reflection model, and specular reflectance parameters for gloss intensity and surface roughness are finally estimated using the least squares method. Experiments were carried out using both methods, with simulation data at different saturation levels, generated according to the Lambert and Torrance-Sparrow reflection models, and the second method, with spectral images captured by an imaging spectrograph and a moving light source. Our results show that the second method can estimate the diffuse and specular reflectance parameters for colors, gloss intensity and surface roughness more accurately and faster than the first one, so that colors and gloss can be reproduced more efficiently for HDR imaging.

Reflection and Non-Reflection of Particle Wavepackets

ERIC Educational Resources Information Center

Cox, Timothy; Lekner, John

2008-01-01

Exact closed-form solutions of the time-dependent Schrodinger equation are obtained, describing the propagation of wavepackets in the neighbourhood of a potential. Examples given include zero reflection, total reflection and partial reflection of the wavepacket, for the sech[superscript 2]x/a, 1/x[superscript 2] and delta(x) potentials,…

Optical properties of human colon tissues in the 350 – 2500 nm spectral range

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

Bashkatov, A N; Genina, E A; Kochubey, V I

2014-08-31

We present the optical characteristics of the mucosa and submucosa of human colon tissue. The experiments are performed in vitro using a LAMBDA 950 spectrophotometer in the 350 – 2500 nm spectral range. The absorption and scattering coefficients and the scattering anisotropy factor are calculated based on the measured diffuse reflectance and total and collimated transmittance spectra using the inverse Monte Carlo method. (laser biophotonics)

Rapid intra-operative diagnosis of kidney cancer by attenuated total reflection infrared spectroscopy of tissue smears.

PubMed

Pucetaite, Milda; Velicka, Martynas; Urboniene, Vidita; Ceponkus, Justinas; Bandzeviciute, Rimante; Jankevicius, Feliksas; Zelvys, Arunas; Sablinskas, Valdas; Steiner, Gerald

2018-05-01

Herein, a technique to analyze air-dried kidney tissue impression smears by means of attenuated total reflection infrared (ATR-IR) spectroscopy is presented. Spectral tumor markers-absorption bands of glycogen-are identified in the ATR-IR spectra of the kidney tissue smear samples. Thin kidney tissue cryo-sections currently used for IR spectroscopic analysis lack such spectral markers as the sample preparation causes irreversible molecular changes in the tissue. In particular, freeze-thaw cycle results in degradation of the glycogen and reduction or complete dissolution of its content. Supervised spectral classification was applied to the recorded spectra of the smears and the test spectra were classified with a high accuracy of 92% for normal tissue and 94% for tumor tissue, respectively. For further development, we propose that combination of the method with optical fiber ATR probes could potentially be used for rapid real-time intra-operative tissue analysis without interfering with either the established protocols of pathological examination or the ordinary workflow of operating surgeon. Such approach could ensure easier transition of the method to clinical applications where it may complement the results of gold standard histopathology examination and aid in more precise resection of kidney tumors. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evanescent excitation and emission in fluorescence microscopy.

PubMed

Axelrod, Daniel

2013-04-02

Evanescent light-light that does not propagate but instead decays in intensity over a subwavelength distance-appears in both excitation (as in total internal reflection) and emission (as in near-field imaging) forms in fluorescence microscopy. This review describes the physical connection between these two forms as a consequence of geometrical squeezing of wavefronts, and describes newly established or speculative applications and combinations of the two. In particular, each can be used in analogous ways to produce surface-selective images, to examine the thickness and refractive index of films (such as lipid multilayers or protein layers) on solid supports, and to measure the absolute distance of a fluorophore to a surface. In combination, the two forms can further increase selectivity and reduce background scattering in surface images. The polarization properties of each lead to more sensitive and accurate measures of fluorophore orientation and membrane micromorphology. The phase properties of the evanescent excitation lead to a method of creating a submicroscopic area of total internal reflection illumination or enhanced-resolution structured illumination. Analogously, the phase properties of evanescent emission lead to a method of producing a smaller point spread function, in a technique called virtual supercritical angle fluorescence. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Identification of fungal phytopathogens using Fourier transform infrared-attenuated total reflection spectroscopy and advanced statistical methods

NASA Astrophysics Data System (ADS)

Salman, Ahmad; Lapidot, Itshak; Pomerantz, Ami; Tsror, Leah; Shufan, Elad; Moreh, Raymond; Mordechai, Shaul; Huleihel, Mahmoud

2012-01-01

The early diagnosis of phytopathogens is of a great importance; it could save large economical losses due to crops damaged by fungal diseases, and prevent unnecessary soil fumigation or the use of fungicides and bactericides and thus prevent considerable environmental pollution. In this study, 18 isolates of three different fungi genera were investigated; six isolates of Colletotrichum coccodes, six isolates of Verticillium dahliae and six isolates of Fusarium oxysporum. Our main goal was to differentiate these fungi samples on the level of isolates, based on their infrared absorption spectra obtained using the Fourier transform infrared-attenuated total reflection (FTIR-ATR) sampling technique. Advanced statistical and mathematical methods: principal component analysis (PCA), linear discriminant analysis (LDA), and k-means were applied to the spectra after manipulation. Our results showed significant spectral differences between the various fungi genera examined. The use of k-means enabled classification between the genera with a 94.5% accuracy, whereas the use of PCA [3 principal components (PCs)] and LDA has achieved a 99.7% success rate. However, on the level of isolates, the best differentiation results were obtained using PCA (9 PCs) and LDA for the lower wavenumber region (800-1775 cm-1), with identification success rates of 87%, 85.5%, and 94.5% for Colletotrichum, Fusarium, and Verticillium strains, respectively.

Optical sensing: recognition elements and devices

NASA Astrophysics Data System (ADS)

Gauglitz, Guenter G.

2012-09-01

The requirements in chemical and biochemical sensing with respect to recognition elements, avoiding non-specific interactions, and high loading of the surface for detection of low concentrations as well as optimized detection systems are discussed. Among the many detection principles the optical techniques are classified. Methods using labeled compounds like Total Internal Reflection Fluorescence (TIRF) and direct optical methods like micro reflectometry or refractometry are discussed in comparison. Reflectometric Interference Spectroscopy (RIfS) is presented as a robust simple method for biosensing. As applications, trace analysis of endocrine disruptors in water, hormones in food, detection of viruses and bacteria in food and clinical diagnostics are discussed.

Fourier Transform-Plasmon Waveguide Spectroscopy: A Nondestructive Multifrequency Method for Simultaneously Determining Polymer Thickness and Apparent Index of Refraction

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

Bobbitt, Jonathan M; Weibel, Stephen C; Elshobaki, Moneim

2014-12-16

Fourier transform (FT)-plasmon waveguide resonance (PWR) spectroscopy measures light reflectivity at a waveguide interface as the incident frequency and angle are scanned. Under conditions of total internal reflection, the reflected light intensity is attenuated when the incident frequency and angle satisfy conditions for exciting surface plasmon modes in the metal as well as guided modes within the waveguide. Expanding upon the concept of two-frequency surface plasmon resonance developed by Peterlinz and Georgiadis [ Opt. Commun. 1996, 130, 260], the apparent index of refraction and the thickness of a waveguide can be measured precisely and simultaneously by FT-PWR with an averagemore » percent relative error of 0.4%. Measuring reflectivity for a range of frequencies extends the analysis to a wide variety of sample compositions and thicknesses since frequencies with the maximum attenuation can be selected to optimize the analysis. Additionally, the ability to measure reflectivity curves with both p- and s-polarized light provides anisotropic indices of refraction. FT-PWR is demonstrated using polystyrene waveguides of varying thickness, and the validity of FT-PWR measurements are verified by comparing the results to data from profilometry and atomic force microscopy (AFM).« less

Fourier transform-plasmon waveguide spectroscopy: a nondestructive multifrequency method for simultaneously determining polymer thickness and apparent index of refraction.

PubMed

Bobbitt, Jonathan M; Weibel, Stephen C; Elshobaki, Moneim; Chaudhary, Sumit; Smith, Emily A

2014-12-16

Fourier transform (FT)-plasmon waveguide resonance (PWR) spectroscopy measures light reflectivity at a waveguide interface as the incident frequency and angle are scanned. Under conditions of total internal reflection, the reflected light intensity is attenuated when the incident frequency and angle satisfy conditions for exciting surface plasmon modes in the metal as well as guided modes within the waveguide. Expanding upon the concept of two-frequency surface plasmon resonance developed by Peterlinz and Georgiadis [Opt. Commun. 1996, 130, 260], the apparent index of refraction and the thickness of a waveguide can be measured precisely and simultaneously by FT-PWR with an average percent relative error of 0.4%. Measuring reflectivity for a range of frequencies extends the analysis to a wide variety of sample compositions and thicknesses since frequencies with the maximum attenuation can be selected to optimize the analysis. Additionally, the ability to measure reflectivity curves with both p- and s-polarized light provides anisotropic indices of refraction. FT-PWR is demonstrated using polystyrene waveguides of varying thickness, and the validity of FT-PWR measurements are verified by comparing the results to data from profilometry and atomic force microscopy (AFM).

Method to adjust multilayer film stress induced deformation of optics

DOEpatents

Spiller, Eberhard A.; Mirkarimi, Paul B.; Montcalm, Claude; Bajt, Sasa; Folta, James A.

2000-01-01

Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system. The components for the stress reducing layer are chosen among materials that have opposite stress to that of the preferred multilayer reflecting stack and simultaneously have optical constants that allow one to get good reflectivity at the design wavelength. For a wavelength of 13.4 nm, the wavelength presently used for extreme ultraviolet (EUV) lithography, Si and Be have practically the same optical constants, but the Mo/Si multilayer has opposite stress than the Mo/Be multilayer. Multilayer systems of these materials have practically identical reflectivity curves. For example, stress free multilayers can be formed on a substrate using Mo/Be multilayers in the bottom of the stack and Mo/Si multilayers at the top of the stack, with the switch-over point selected to obtain zero stress. In this multilayer system, the switch-over point is at about the half point of the total thickness of the stack, and for the Mo/Be--Mo/Si system, there may be 25 deposition periods Mo/Be to 20 deposition periods Mo/Si.

Exploration of attenuated total reflectance mid-infrared spectroscopy and multivariate calibration to measure immunoglobulin G in human sera.

PubMed

Hou, Siyuan; Riley, Christopher B; Mitchell, Cynthia A; Shaw, R Anthony; Bryanton, Janet; Bigsby, Kathryn; McClure, J Trenton

2015-09-01

Immunoglobulin G (IgG) is crucial for the protection of the host from invasive pathogens. Due to its importance for human health, tools that enable the monitoring of IgG levels are highly desired. Consequently there is a need for methods to determine the IgG concentration that are simple, rapid, and inexpensive. This work explored the potential of attenuated total reflectance (ATR) infrared spectroscopy as a method to determine IgG concentrations in human serum samples. Venous blood samples were collected from adults and children, and from the umbilical cord of newborns. The serum was harvested and tested using ATR infrared spectroscopy. Partial least squares (PLS) regression provided the basis to develop the new analytical methods. Three PLS calibrations were determined: one for the combined set of the venous and umbilical cord serum samples, the second for only the umbilical cord samples, and the third for only the venous samples. The number of PLS factors was chosen by critical evaluation of Monte Carlo-based cross validation results. The predictive performance for each PLS calibration was evaluated using the Pearson correlation coefficient, scatter plot and Bland-Altman plot, and percent deviations for independent prediction sets. The repeatability was evaluated by standard deviation and relative standard deviation. The results showed that ATR infrared spectroscopy is potentially a simple, quick, and inexpensive method to measure IgG concentrations in human serum samples. The results also showed that it is possible to build a united calibration curve for the umbilical cord and the venous samples. Copyright © 2015 Elsevier B.V. All rights reserved.

FT-IR/ATR univariate and multivariate calibration models for in situ monitoring of sugars in complex microalgal culture media.

PubMed

Girard, Jean-Michel; Deschênes, Jean-Sébastien; Tremblay, Réjean; Gagnon, Jonathan

2013-09-01

The objective of this work is to develop a quick and simple method for the in situ monitoring of sugars in biological cultures. A new technology based on Attenuated Total Reflectance-Fourier Transform Infrared (FT-IR/ATR) spectroscopy in combination with an external light guiding fiber probe was tested, first to build predictive models from solutions of pure sugars, and secondly to use those models to monitor the sugars in the complex culture medium of mixotrophic microalgae. Quantification results from the univariate model were correlated with the total dissolved solids content (R(2)=0.74). A vector normalized multivariate model was used to proportionally quantify the different sugars present in the complex culture medium and showed a predictive accuracy of >90% for sugars representing >20% of the total. This method offers an alternative to conventional sugar monitoring assays and could be used at-line or on-line in commercial scale production systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

Lebanese household carbon footprint: Measurements, analysis and challenges

NASA Astrophysics Data System (ADS)

Nasr, Rawad; Tall, Ibrahim; Nachabe, Nour; Chaaban, Farid

2016-07-01

The main purpose of this paper is to estimate the carbon footprint of a typical Lebanese household, and compare the results with international standards and trends. The estimation of this footprint will reflect the impact of the daily Lebanese household activities on the environment in terms of carbon dioxide emissions. The method used in estimating the carbon emissions is based on gathering the primary footprints from various household activities. Another proposed method that provides more accurate results is the estimation of emissions based on secondary footprint, which reflects the total emissions not only from the regular activities but also from a lifecycle perspective. Practical and feasible solutions were proposed to help reduce the amount of C02 emissions per household. This would lead to a better air quality, money savings, greenhouse gases emissions reduction and would ensure the sustainability and prosperity of future generations. A detailed survey was conducted in which the questions were focused mainly on energy, food, and transportation issues. The fourteen questions were addressed to one hundred families in different Lebanese regions coming from different social and economic backgrounds. This diversity would constitute a reflective sample of the actual Lebanese society, allowing us to extrapolate the gathered results on a national level.

Mechanical modulation method for ultrasensitive phase measurements in photonics biosensing.

PubMed

Patskovsky, S; Maisonneuve, M; Meunier, M; Kabashin, A V

2008-12-22

A novel polarimetry methodology for phase-sensitive measurements in single reflection geometry is proposed for applications in optical transduction-based biological sensing. The methodology uses altering step-like chopper-based mechanical phase modulation for orthogonal s- and p- polarizations of light reflected from the sensing interface and the extraction of phase information at different harmonics of the modulation. We show that even under a relatively simple experimental arrangement, the methodology provides the resolution of phase measurements as low as 0.007 deg. We also examine the proposed approach using Total Internal Reflection (TIR) and Surface Plasmon Resonance (SPR) geometries. For TIR geometry, the response appears to be strongly dependent on the prism material with the best values for high refractive index Si. The detection limit for Si-based TIR is estimated as 10(-5) in terms Refractive Index Units (RIU) change. SPR geometry offers much stronger phase response due to a much sharper phase characteristics. With the detection limit of 3.2*10(-7) RIU, the proposed methodology provides one of best sensitivities for phase-sensitive SPR devices. Advantages of the proposed method include high sensitivity, simplicity of experimental setup and noise immunity as a result of a high stability modulation.

A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy

PubMed Central

Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

2016-01-01

Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion. PMID:27025266

A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy.

PubMed

Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

2016-03-30

Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion.

Quantification of bovine immunoglobulin G using transmission and attenuated total reflectance infrared spectroscopy.

PubMed

Elsohaby, Ibrahim; McClure, J Trenton; Riley, Christopher B; Shaw, R Anthony; Keefe, Gregory P

2016-01-01

In this study, we evaluated and compared the performance of transmission and attenuated total reflectance (ATR) infrared (IR) spectroscopic methods (in combination with quantification algorithms previously developed using partial least squares regression) for the rapid measurement of bovine serum immunoglobulin G (IgG) concentration, and detection of failure of transfer of passive immunity (FTPI) in dairy calves. Serum samples (n = 200) were collected from Holstein calves 1-11 days of age. Serum IgG concentrations were measured by the reference method of radial immunodiffusion (RID) assay, transmission IR (TIR) and ATR-IR spectroscopy-based assays. The mean IgG concentration measured by RID was 17.22 g/L (SD ±9.60). The mean IgG concentrations predicted by TIR and ATR-IR spectroscopy methods were 15.60 g/L (SD ±8.15) and 15.94 g/L (SD ±8.66), respectively. RID IgG concentrations were positively correlated with IgG levels predicted by TIR (r = 0.94) and ATR-IR (r = 0.92). The correlation between 2 IR spectroscopic methods was 0.94. Using an IgG concentration <10 g/L as the cut-point for FTPI cases, the overall agreement between TIR and ATR-IR methods was 94%, with a corresponding kappa value of 0.84. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for identifying FTPI by TIR were 0.87, 0.97, 0.91, 0.95, and 0.94, respectively. Corresponding values for ATR-IR were 0.87, 0.95, 0.86, 0.95, and 0.93, respectively. Both TIR and ATR-IR spectroscopic approaches can be used for rapid quantification of IgG level in neonatal bovine serum and for diagnosis of FTPI in dairy calves. © 2015 The Author(s).

Standardization of vitrinite reflectance measurements in shale petroleum systems: How accurate are my Ro data?

USGS Publications Warehouse

Hackley, Paul C.

2014-01-01

Vitrinite reflectance generally is considered the most robust thermal maturity parameter available for application to hydrocarbon exploration and petroleum system evaluation. However, until 2011 there was no standardized methodology available to provide guidelines for vitrinite reflectance measurements in shale. Efforts to correct this deficiency resulted in publication of ASTM D7708-11: Standard test method for microscopical determination of the reflectance of vitrinite dispersed in sedimentary rocks. In 2012-2013, an interlaboratory exercise was conducted to establish precision limits for the measurement technique. Six samples, representing a wide variety of shale, were tested in duplicate by 28 analysts in 22 laboratories from 14 countries. Samples ranged from immature to overmature (Ro 0.31-1.53%), from organic-rich to organic-lean (1-22 wt.% total organic carbon), and contained Type I (lacustrine), Type II (marine), and Type III (terrestrial) kerogens. Repeatability values (difference between repetitive results from same operator, same conditions) ranged from 0.03-0.11% absolute reflectance, whereas reproducibility values (difference between results obtained on same test material by different operators, different laboratories) ranged from 0.12-0.54% absolute reflectance. Repeatability and reproducibility degraded consistently with increasing maturity and decreasing organic content. However, samples with terrestrial kerogens (Type III) fell off this trend, showing improved levels of reproducibility due to higher vitrinite content and improved ease of identification. Operators did not consistently meet the reporting requirements of the test method, indicating that a common reporting template is required to improve data quality. The most difficult problem encountered was the petrographic distinction of solid bitumens and low-reflecting inert macerals from vitrinite when vitrinite occurred with reflectance ranges overlapping the other components. Discussion among participants suggested this problem could not be corrected via kerogen concentration or solvent extraction and is related to operator training and background. Poor reproducibility (0.54% absolute reflectance, related to increased anisotropy?) in the highest maturity sample (Ro 1.53%) suggests that vitrinite reflectance is not a highly reliable parameter in such rocks. Future work will investigate opportunities to improve reproducibility in similar high maturity, organic-lean shale varieties.

Studying flow close to an interface by total internal reflection fluorescence cross-correlation spectroscopy: Quantitative data analysis

NASA Astrophysics Data System (ADS)

Schmitz, R.; Yordanov, S.; Butt, H. J.; Koynov, K.; Dünweg, B.

2011-12-01

Total internal reflection fluorescence cross-correlation spectroscopy (TIR-FCCS) has recently [S. Yordanov , Optics ExpressOPEXFF1094-408710.1364/OE.17.021149 17, 21149 (2009)] been established as an experimental method to probe hydrodynamic flows near surfaces, on length scales of tens of nanometers. Its main advantage is that fluorescence occurs only for tracer particles close to the surface, thus resulting in high sensitivity. However, the measured correlation functions provide only rather indirect information about the flow parameters of interest, such as the shear rate and the slip length. In the present paper, we show how to combine detailed and fairly realistic theoretical modeling of the phenomena by Brownian dynamics simulations with accurate measurements of the correlation functions, in order to establish a quantitative method to retrieve the flow properties from the experiments. First, Brownian dynamics is used to sample highly accurate correlation functions for a fixed set of model parameters. Second, these parameters are varied systematically by means of an importance-sampling Monte Carlo procedure in order to fit the experiments. This provides the optimum parameter values together with their statistical error bars. The approach is well suited for massively parallel computers, which allows us to do the data analysis within moderate computing times. The method is applied to flow near a hydrophilic surface, where the slip length is observed to be smaller than 10nm, and, within the limitations of the experiments and the model, indistinguishable from zero.

Estimating the leaf nitrogen content of paddy rice by using the combined reflectance and laser-induced fluorescence spectra.

PubMed

Yang, Jian; Du, Lin; Sun, Jia; Zhang, Zhenbing; Chen, Biwu; Shi, Shuo; Gong, Wei; Song, Shalei

2016-08-22

Paddy rice is one of the most important crops in China, and leaf nitrogen content (LNC) serves as a significant indictor for monitoring crop status. A reliable method is needed for precise and fast quantification of LNC. Laser-induced fluorescence (LIF) technology and reflectance spectra of crops are widely used to monitor leaf biochemical content. However, comparison between the fluorescence and reflectance spectra has been rarely investigated in the monitoring of LNC. In this study, the performance of the fluorescence and reflectance spectra for LNC estimation was discussed based on principal component analysis (PCA) and back-propagation neural network (BPNN). The combination of fluorescence and reflectance spectra was also proposed to monitor paddy rice LNC. The fluorescence and reflectance spectra exhibited a high degree of multi-collinearity. About 95.38%, and 97.76% of the total variance included in the spectra were efficiently extracted by using the first three PCs in PCA. The BPNN was implemented for LNC prediction based on new variables calculated using PCA. The experimental results demonstrated that the fluorescence spectra (R² = 0.810, 0.804 for 2014 and 2015, respectively) are superior to the reflectance spectra (R² = 0.721, 0.671 for 2014 and 2015, respectively) for estimating LNC based on the PCA-BPNN model. The proposed combination of fluorescence and reflectance spectra can greatly improve the accuracy of LNC estimation (R² = 0.912, 0.890 for 2014 and 2015, respectively).

Estimation of total discharged mass from the phreatic eruption of Ontake Volcano, central Japan, on September 27, 2014

NASA Astrophysics Data System (ADS)

Takarada, Shinji; Oikawa, Teruki; Furukawa, Ryuta; Hoshizumi, Hideo; Itoh, Jun'ichi; Geshi, Nobuo; Miyagi, Isoji

2016-08-01

The total mass discharged by the phreatic eruption of Ontake Volcano, central Japan, on September 27, 2014, was estimated using several methods. The estimated discharged mass was 1.2 × 106 t (segment integration method), 8.9 × 105 t (Pyle's exponential method), and varied from 8.6 × 103 to 2.5 × 106 t (Hayakawa's single isopach method). The segment integration and Pyle's exponential methods gave similar values. The single isopach method, however, gave a wide range of results depending on which contour was used. Therefore, the total discharged mass of the 2014 eruption is estimated at between 8.9 × 105 and 1.2 × 106 t. More than 90 % of the total mass accumulated within the proximal area. This shows how important it is to include a proximal area field survey for the total mass estimation of phreatic eruptions. A detailed isopleth mass distribution map was prepared covering as far as 85 km from the source. The main ash-fall dispersal was ENE in the proximal and medial areas and E in the distal area. The secondary distribution lobes also extended to the S and NW proximally, reflecting the effects of elutriation ash and surge deposits from pyroclastic density currents during the phreatic eruption. The total discharged mass of the 1979 phreatic eruption was also calculated for comparison. The resulting volume of 1.9 × 106 t (using the segment integration method) indicates that it was about 1.6-2.1 times larger than the 2014 eruption. The estimated average discharged mass flux rate of the 2014 eruption was 1.7 × 108 kg/h and for the 1979 eruption was 1.0 × 108 kg/h. One of the possible reasons for the higher flux rate of the 2014 eruption is the occurrence of pyroclastic density currents at the summit area.

Multi-satellites normalization of the FengYun-2s visible detectors by the MVP method

NASA Astrophysics Data System (ADS)

Li, Yuan; Rong, Zhi-guo; Zhang, Li-jun; Sun, Ling; Xu, Na

2013-08-01

After January 13, 2012, FY-2F had successfully launched, the total number of the in orbit operating FengYun-2 geostationary meteorological satellites reached three. For accurate and efficient application of multi-satellite observation data, the study of the multi-satellites normalization of the visible detector was urgent. The method required to be non-rely on the in orbit calibration. So as to validate the calibration results before and after the launch; calculate day updating surface bidirectional reflectance distribution function (BRDF); at the same time track the long-term decay phenomenon of the detector's linearity and responsivity. By research of the typical BRDF model, the normalization method was designed. Which could effectively solute the interference of surface directional reflectance characteristics, non-rely on visible detector in orbit calibration. That was the Median Vertical Plane (MVP) method. The MVP method was based on the symmetry of principal plane, which were the directional reflective properties of the general surface targets. Two geostationary satellites were taken as the endpoint of a segment, targets on the intersecting line of the segment's MVP and the earth surface could be used as a normalization reference target (NRT). Observation on the NRT by two satellites at the moment the sun passing through the MVP brought the same observation zenith, solar zenith, and opposite relative direction angle. At that time, the linear regression coefficients of the satellite output data were the required normalization coefficients. The normalization coefficients between FY-2D, FY-2E and FY-2F were calculated, and the self-test method of the normalized results was designed and realized. The results showed the differences of the responsivity between satellites could up to 10.1%(FY-2E to FY-2F); the differences of the output reflectance calculated by the broadcast calibration look-up table could up to 21.1%(FY-2D to FY-2F); the differences of the output reflectance from FY-2D and FY-2E calculated by the site experiment results reduced to 2.9%(13.6% when using the broadcast table). The normalized relative error was also calculated by the self-test method, which was less than 0.2%.

Publications - GMC 126 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 126 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Reference Unknown, 1989, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance data of Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources, Division of Geological

Publications - GMC 143 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 143 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Reference Unknown, 1989, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance data of Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources, Division of Geological

Publications - GMC 66 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 66 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Reference Unknown, 1987, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance geochemical Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources, Division of Geological

Publications - GMC 142 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 142 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Reference Unknown, 1989, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance data of Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources, Division of Geological

Resonant tunneling in frustrated total internal reflection.

PubMed

Longhi, Stefano

2005-10-15

Anomalous light transmission and resonant tunneling in frustrated total internal reflection (FTIR) are theoretically predicted to occur at periodically curved interfaces. For a low-contrast index and for grazing incidence, it is shown that FTIR resonant tunneling provides an optical realization of field-induced barrier transparency in quantum tunneling.

Concentration of Elements in Food: How Can It Reflect Impact of Environmental and Other Influencing Factors?

NASA Astrophysics Data System (ADS)

Vincevica-Gaile, Zane; Klavins, Maris

2013-12-01

Element content of food is variable and can be influenced by different factors. The aim of the present study was to discover the linkage between macro- and microelement concentrations in food produced in Latvia, and possible impacts of environmental factors. More than 300 fresh food samples such as eggs, cottage cheese, honey, root vegetables, apple juice, apple wine were collected in the time period from 2009 to 2011. Samples were mineralised or analysed directly by appropriate method of quantitative analysis: atomic absorption spectrometry, inductively coupled plasma mass spectrometry or total reflection X-ray fluorescence spectrometry. Statistical analysis of data revealed that food elemental content can be influenced by sitespecific factors such as geographical origin, seasonality, environmental pollution.

Evaluation of glass resin coatings for solar cell applications

NASA Technical Reports Server (NTRS)

Field, M. B.

1978-01-01

Using a variety of non-vacuum deposition techniques coatings were implemented on silicon solar cells and arrays of cells interconnected on Kapton substrates. The coatings provide both antireflection optical matching and environmental protection. Reflectance minima near 2% was achieved at a single wavelength in the visible. Reflectance averaging below 5% across the useful collection range was demonstrated. The coatings and methods of deposition were: (1) Ta2O5 spun, dipped or sprayed; (2) Ta2O5.SiO2 spun, dipped or sprayed; (3) GR908 (SiO2) spun, dipped, or sprayed. Total coating thickness were in the range of 18 microns to 25 microns. The coatings and processes are compatible with single cells or cells mounted on Kapton substrates.

High Resolution Ecosystem Structure, Biomass and Blue Carbon stocks in Mangrove Ecosystems- Methods and Applications of Lidar, radar Interferometry and High Resolution imagery

NASA Astrophysics Data System (ADS)

Lagomasino, D.; Fatoyinbo, T. E.; Lee, S. K.; Feliciano, E. A.; Simard, M.; Trettin, C.

2016-12-01

Earth's climate is determined by the exchange of radiant energy between the Sun, Earth and space. The absorbed solar radiation (ASR) fuels the climate system, providing the energy required for atmospheric and oceanic motions, while the system cools by emitting outgoing longwave (LW) radiation to space. A central objective of the Clouds and the Earth's Radiant Energy System (CERES) is to produce a long-term global climate data record of Earth's radiation budget along with the associated atmospheric and surface properties that influence it. CERES data products utilize a number of data sources, including broadband radiometers measuring incoming and reflected solar radiation and OLR, polar orbiting and geostationary spectral imagers, meteorological, aerosol and ozone assimilation data, and snow/sea-ice maps based on microwave radiometer data. Here we use simple diagnostic model of Earth's albedo and CERES Energy Balanced and Filled (EBAF) Ed4.0 data for March 2000-February 2016 to quantify interannual variations in SW TOA flux associated with surface albedo and atmospheric reflectance and transmittance variations. Surface albedo variations account for <0.5% of the total SW TOA flux variance over the tropics and 4% globally. Variations in atmospheric reflectance and transmittance account for virtually all of the total SW TOA flux variance over the tropics and only 81% globally. The remaining 15% of the global SW TOA flux variance is explained by the co-variance of surface albedo and atmospheric reflectance/transmittance. Equatorward of 60-degree latitude, the atmospheric contribution exceeds that of the surface by at least an order-of-magnitude. In contrast, the surface and atmospheric variations contribute equally poleward of 60S and surface variations account for twice as much as the atmosphere poleward of 60N. However, as much as 40% of the total SW TOA flux variance poleward of 60N is explained by the covariance of surface albedo and atmospheric reflectance/transmittance, highlighting the tight coupling between sea-ice concentration and cloud properties over the Arctic Ocean.

The use of 2D and 3D WA-BPM models to analyze total-internal-reflection-based integrated optical switches

NASA Astrophysics Data System (ADS)

Wang, Pengfei; Brambilla, Gilberto; Semenova, Yuliya; Wu, Qiang; Zheng, Jie; Farrell, Gerald

2011-08-01

The well known beam propagation method (BPM) has become one of the most useful, robust and effective numerical simulation tools for the investigation of guided-wave optics, for example integrated optical waveguides and fiber optic devices. In this paper we examine the use of the 2D and 3D wide angle-beam propagation method (WA-BPM) combined with the well known perfectly matched layer (PML) boundary conditions as a tool to analyze TIR based optical switches, in particular the relationship between light propagation and the geometrical parameters of a TIR based optical switch. To analyze the influence of the length and the width of the region in which the refractive index can be externally controlled, the 3D structure of a 2x2 TIR optical switch is firstly considered in 2D using the effective index method (EIM). Then the influence of the etching depth and the tilt angle of the reflection facet on the switch performance are investigated with a 3D model.

Direct method for imaging elemental distribution profiles with long-period x-ray standing waves

NASA Astrophysics Data System (ADS)

Kohli, Vaibhav; Bedzyk, Michael J.; Fenter, Paul

2010-02-01

A model-independent Fourier-inversion method for imaging elemental profiles from multilayer and total-external reflection x-ray standing wave (XSW) data is developed for the purpose of understanding the assembly of atoms, ions, and molecules at well-defined interfaces in complex environments. The direct-method formalism is derived for the case of a long-period XSW generated by low-angle specular reflection in an attenuating overlayer medium. It is validated through comparison with simulated and experimental data to directly obtain an elemental distribution contained within the overlayer. We demonstrate this formalism by extracting the one-dimensional profile of Ti normal to the surface for a TiO2/Si/Mo trilayer deposited on a Si substrate using the TiKα fluorescence yield measured in air and under an aqueous electrolyte. The model-independent results demonstrate reduced coherent fractions for the in situ results associated with an incoherency of the x-ray beam (which are attributed to fluorescence excitation by diffusely or incoherently scattered x-rays). The uniqueness and limitations of the approach are discussed.

Optimum Solar Conversion Cell Configurations

NASA Technical Reports Server (NTRS)

Chen, Bin (Inventor)

2015-01-01

Methods for maximizing a fraction of light energy absorbed in each of three classes of light concentrators (rectangular parallelepipeds, paraboloids and prisms) by choice of incident angle of radiation and of one or more geometrical or physical parameters (absorber thickness, paraboloid dimensions, location of paraboloid focus, prism angles, concentrator material, cladding, prism angles, etc.). Alternatively, the light energy absorbed plus the light energy that escapes through non-total internal reflection within the light concentrator can be minimized.

Standardization of reflectance measurements in dispersed organic matter: results of an exercise to improve interlaboratory agreement

USGS Publications Warehouse

Hackley, Paul C.; Araujo, Carla Viviane; Borrego, Angeles G.; Bouzinos, Antonis; Cardott, Brian; Cook, Alan C.; Eble, Cortland; Flores, Deolinda; Gentzis, Thomas; Gonçalves, Paula Alexandra; Filho, João Graciano Mendonça; Hámor-Vidó, Mária; Jelonek, Iwona; Kommeren, Kees; Knowles, Wayne; Kus, Jolanta; Mastalerz, Maria; Menezes, Taíssa Rêgo; Newman, Jane; Pawlewicz, Mark; Pickel, Walter; Potter, Judith; Ranasinghe, Paddy; Read, Harold; Reyes, Julito; Rodriguez, Genaro De La Rosa; de Souza, Igor Viegas Alves Fernandes; Suarez-Ruiz, Isabel; Sýkorová, Ivana; Valentine, Brett J.

2015-01-01

Vitrinite reflectance generally is considered the most robust thermal maturity parameter available for application to hydrocarbon exploration and petroleum system evaluation. However, until 2011 there was no standardized methodology available to provide guidelines for vitrinite reflectance measurements in shale. Efforts to correct this deficiency resulted in publication of ASTM D7708: Standard test method for microscopical determination of the reflectance of vitrinite dispersed in sedimentary rocks. In 2012-2013, an interlaboratory exercise was conducted to establish precision limits for the D7708 measurement technique. Six samples, representing a wide variety of shale, were tested in duplicate by 28 analysts in 22 laboratories from 14 countries. Samples ranged from immature to overmature (0.31-1.53% Ro), from organic-lean to organic-rich (1-22 wt.% total organic carbon), and contained Type I (lacustrine), Type II (marine), and Type III (terrestrial) kerogens. Repeatability limits (maximum difference between valid repetitive results from same operator, same conditions) ranged from 0.03-0.11% absolute reflectance, whereas reproducibility limits (maximum difference between valid results obtained on same test material by different operators, different laboratories) ranged from 0.12-0.54% absolute reflectance. Repeatability and reproducibility limits degraded consistently with increasing maturity and decreasing organic content. However, samples with terrestrial kerogens (Type III) fell off this trend, showing improved levels of reproducibility due to higher vitrinite content and improved ease of identification. Operators did not consistently meet the reporting requirements of the test method, indicating that a common reporting template is required to improve data quality. The most difficult problem encountered was the petrographic distinction of solid bitumens and low-reflecting inert macerals from vitrinite when vitrinite occurred with reflectance ranges overlapping the other components. Discussion among participants suggested this problem could not be easily corrected via kerogen concentration or solvent extraction and is related to operator training and background. No statistical difference in mean reflectance was identified between participants reporting bitumen reflectance vs. vitrinite reflectance vs. a mixture of bitumen and vitrinite reflectance values, suggesting empirical conversion schemes should be treated with caution. Analysis of reproducibility limits obtained during this exercise in comparison to reproducibility limits from historical interlaboratory exercises suggests use of a common methodology (D7708) improves interlaboratory precision. Future work will investigate opportunities to improve reproducibility in high maturity, organic-lean shale varieties.

A method of treating the non-grey error in total emittance measurements

NASA Technical Reports Server (NTRS)

Heaney, J. B.; Henninger, J. H.

1971-01-01

In techniques for the rapid determination of total emittance, the sample is generally exposed to surroundings that are at a different temperature than the sample's surface. When the infrared spectral reflectance of the surface is spectrally selective, these techniques introduce an error into the total emittance values. Surfaces of aluminum overcoated with oxides of various thicknesses fall into this class. Because they are often used as temperature control coatings on satellites, their emittances must be accurately known. The magnitude of the error was calculated for Alzak and silicon oxide-coated aluminum and was shown to be dependent on the thickness of the oxide coating. The results demonstrate that, because the magnitude of the error is thickness-dependent, it is generally impossible or impractical to eliminate it by calibrating the measuring device.

Review of infrared scene projector technology-1993

NASA Astrophysics Data System (ADS)

Driggers, Ronald G.; Barnard, Kenneth J.; Burroughs, E. E.; Deep, Raymond G.; Williams, Owen M.

1994-07-01

The importance of testing IR imagers and missile seekers with realistic IR scenes warrants a review of the current technologies used in dynamic infrared scene projection. These technologies include resistive arrays, deformable mirror arrays, mirror membrane devices, liquid crystal light valves, laser writers, laser diode arrays, and CRTs. Other methods include frustrated total internal reflection, thermoelectric devices, galvanic cells, Bly cells, and vanadium dioxide. A description of each technology is presented along with a discussion of their relative benefits and disadvantages. The current state of each methodology is also summarized. Finally, the methods are compared and contrasted in terms of their performance parameters.

Fine modeling of reinforced thermoplastic filament winding container

NASA Astrophysics Data System (ADS)

Duan, Chenghong; Huang, Jinhao; Wu, Liang; Luo, Xiangpeng

2018-05-01

Reinforced thermoplastic containers has been widely used because of its corrosion-resistant, fatigue-resistant features. The characteristics of the liner and wound layer material and the different winding methods lead to the fact that the model obtained according to the ordinary pressure vessel modeling method does not reflect the actual situation of the reinforced thermoplastic container. In this paper, the thickness of stratified winding was calculated based on the principle of constant fiber total volume and equal cross-sectional area. ANSYS ACP module was used to refine the full winding container and provide a reference for engineering simulation solution.

Effects of cultivar, fruit number and reflected photosynthetically active radiation on Fragaria x ananassa productivity and fruit ellagic acid and ascorbic acid concentrations.

PubMed

Atkinson, C J; Dodds, P A A; Ford, Y Y; Le Mière, J; Taylor, J M; Blake, P S; Paul, N

2006-03-01

A number of strawberry varieties were surveyed for their total ellagic acid concentration, and attempts were made to determine if ellagic acid and ascorbic acid concentrations of two strawberry cultivars could be increased by polythene reflective mulches. After adjusting crop yields and cultivation using polythene mulches with two different PAR reflective capacities, field- and polytunnel-grown strawberries were analysed for ellagic acid and ascorbic acid concentrations by HPLC. Comparative measurements of yield and fruit quality were determined along with plant developmental changes. Ellagic acid concentration varied widely with strawberry cultivar (60-341 microg g(-1) frozen weight), as did the ratio of conjugated ellagic acid : free ellagic acid. Also, there was significant year-to-year variation in total ellagic acid concentration with some cultivars. Mulches with different reflective capacities impacted on strawberry production; highly reflective mulches significantly increased growth and yield, the latter due to increases in fruit size and number. Highly reflective mulches significantly increased total concentrations of ellagic acid and ascorbic acid relative to control in fruit of different cultivars. The potential of agronomic practices to enhance the concentration and amounts of these important dietary bioactive compounds is discussed.

Colorimetric Solid Phase Extraction for the Measurement of Total I (Iodine, Iodide, and Triiodide) in Spacecraft Drinking Water

NASA Technical Reports Server (NTRS)

Lipert, Robert J.; Porter, Marc D.; Siperko, Lorraine M.; Gazda, Daniel B.; Rutz, Jeff A.; Schultz, John R.; Carrizales, Stephanie M.; McCoy, J. Torin

2009-01-01

An experimental drinking water monitoring kit for the measurement of iodine and silver(I) was recently delivered to the International Space Station (ISS). The kit is based on Colorimetric Solid Phase Extraction (CSPE) technology, which measures the change in diffuse reflectance of indicator disks following exposure to a water sample. To satisfy additional spacecraft water monitoring requirements, CSPE has now been extended to encompass the measurement of total I (iodine, iodide, and triiodide) through the introduction of an oxidizing agent, which converts iodide and triiodide to iodine, for measurement using the same indicator disks currently being tested on ISS. These disks detect iodine, but are insensitive to iodide and triiodide. We report here the operational considerations, design, and ground-based performance of the CSPE method for total I. The results demonstrate that CSPE technology is poised to meet NASA's total I monitoring requirements.

A new spectrometer for total reflection X-ray fluorescence analysis of light elements

NASA Astrophysics Data System (ADS)

Streli, Christina; Wobrauschek, Peter; Unfried, Ernst; Aiginger, Hannes

1993-10-01

A new spectrometer for total reflection X-ray fluorescence analysis (TXRF) of light elements as C, N, O, F, Na,… has been designed, constructed and realized. This was done under the aspect of optimizing all relevant parameters for excitation and detection under the conditions of Total Reflection in a vacuum chamber. A commercially available Ge(HP) detector with a diamond window offering a high transparency for low energy radiation was used. As excitation sources a special self-made windowless X-ray tube with Cu-target as well as a standard fine-focus Cr-tube were applied. Detection limits achieved are in the ng range for Carbon and Oxygen.

Even illumination in total internal reflection fluorescence microscopy using laser light.

PubMed

Fiolka, R; Belyaev, Y; Ewers, H; Stemmer, A

2008-01-01

In modern fluorescence microscopy, lasers are a widely used source of light, both for imaging in total internal reflection and epi-illumination modes. In wide-field imaging, scattering of highly coherent laser light due to imperfections in the light path typically leads to nonuniform illumination of the specimen, compromising image analysis. We report the design and construction of an objective-launch total internal reflection fluorescence microscopy system with excellent evenness of specimen illumination achieved by azimuthal rotation of the incoming illuminating laser beam. The system allows quick and precise changes of the incidence angle of the laser beam and thus can also be used in an epifluorescence mode. 2007 Wiley-Liss, Inc

Multiple attenuation to reflection seismic data using Radon filter and Wave Equation Multiple Rejection (WEMR) method

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

Erlangga, Mokhammad Puput

Separation between signal and noise, incoherent or coherent, is important in seismic data processing. Although we have processed the seismic data, the coherent noise is still mixing with the primary signal. Multiple reflections are a kind of coherent noise. In this research, we processed seismic data to attenuate multiple reflections in the both synthetic and real seismic data of Mentawai. There are several methods to attenuate multiple reflection, one of them is Radon filter method that discriminates between primary reflection and multiple reflection in the τ-p domain based on move out difference between primary reflection and multiple reflection. However, inmore » case where the move out difference is too small, the Radon filter method is not enough to attenuate the multiple reflections. The Radon filter also produces the artifacts on the gathers data. Except the Radon filter method, we also use the Wave Equation Multiple Elimination (WEMR) method to attenuate the long period multiple reflection. The WEMR method can attenuate the long period multiple reflection based on wave equation inversion. Refer to the inversion of wave equation and the magnitude of the seismic wave amplitude that observed on the free surface, we get the water bottom reflectivity which is used to eliminate the multiple reflections. The WEMR method does not depend on the move out difference to attenuate the long period multiple reflection. Therefore, the WEMR method can be applied to the seismic data which has small move out difference as the Mentawai seismic data. The small move out difference on the Mentawai seismic data is caused by the restrictiveness of far offset, which is only 705 meter. We compared the real free multiple stacking data after processing with Radon filter and WEMR process. The conclusion is the WEMR method can more attenuate the long period multiple reflection than the Radon filter method on the real (Mentawai) seismic data.« less

The effects of core-reflected waves on finite fault inversions with teleseismic body wave data

NASA Astrophysics Data System (ADS)

Qian, Yunyi; Ni, Sidao; Wei, Shengji; Almeida, Rafael; Zhang, Han

2017-11-01

Teleseismic body waves are essential for imaging rupture processes of large earthquakes. Earthquake source parameters are usually characterized by waveform analyses such as finite fault inversions using only turning (direct) P and SH waves without considering the reflected phases from the core-mantle boundary (CMB). However, core-reflected waves such as ScS usually have amplitudes comparable to direct S waves due to the total reflection from the CMB and might interfere with the S waves used for inversion, especially at large epicentral distances for long duration earthquakes. In order to understand how core-reflected waves affect teleseismic body wave inversion results, we develop a procedure named Multitel3 to compute Green's functions that contain turning waves (direct P, pP, sP, direct S, sS and reverberations in the crust) and core-reflected waves (PcP, pPcP, sPcP, ScS, sScS and associated reflected phases from the CMB). This ray-based method can efficiently generate synthetic seismograms for turning and core-reflected waves independently, with the flexibility to take into account the 3-D Earth structure effect on the timing between these phases. The performance of this approach is assessed through a series of numerical inversion tests on synthetic waveforms of the 2008 Mw7.9 Wenchuan earthquake and the 2015 Mw7.8 Nepal earthquake. We also compare this improved method with the turning-wave only inversions and explore the stability of the new procedure when there are uncertainties in a priori information (such as fault geometry and epicentre location) or arrival time of core-reflected phases. Finally, a finite fault inversion of the 2005 Mw8.7 Nias-Simeulue earthquake is carried out using the improved Green's functions. Using enhanced Green's functions yields better inversion results as expected. While the finite source inversion with conventional P and SH waves is able to recover large-scale characteristics of the earthquake source, by adding PcP and ScS phases, the inverted slip model and moment rate function better match previous results incorporating field observations, geodetic and seismic data.

Secondary cell wall development in cotton fibers as examined with attenuated total reflection Fourier transform infrared spectroscopy

USDA-ARS?s Scientific Manuscript database

Cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering were examined using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. The selected harvesting points coincide with secondary cell wall (SCW) development in the fibers. Progressive but moderat...

Total sulfur determination in residues of crude oil distillation using FT-IR/ATR and variable selection methods

NASA Astrophysics Data System (ADS)

Müller, Aline Lima Hermes; Picoloto, Rochele Sogari; Mello, Paola de Azevedo; Ferrão, Marco Flores; dos Santos, Maria de Fátima Pereira; Guimarães, Regina Célia Lourenço; Müller, Edson Irineu; Flores, Erico Marlon Moraes

2012-04-01

Total sulfur concentration was determined in atmospheric residue (AR) and vacuum residue (VR) samples obtained from petroleum distillation process by Fourier transform infrared spectroscopy with attenuated total reflectance (FT-IR/ATR) in association with chemometric methods. Calibration and prediction set consisted of 40 and 20 samples, respectively. Calibration models were developed using two variable selection models: interval partial least squares (iPLS) and synergy interval partial least squares (siPLS). Different treatments and pre-processing steps were also evaluated for the development of models. The pre-treatment based on multiplicative scatter correction (MSC) and the mean centered data were selected for models construction. The use of siPLS as variable selection method provided a model with root mean square error of prediction (RMSEP) values significantly better than those obtained by PLS model using all variables. The best model was obtained using siPLS algorithm with spectra divided in 20 intervals and combinations of 3 intervals (911-824, 823-736 and 737-650 cm-1). This model produced a RMSECV of 400 mg kg-1 S and RMSEP of 420 mg kg-1 S, showing a correlation coefficient of 0.990.

Comparison of the college alumnus questionnaire physical activity index with objective monitoring.

PubMed

Strath, Scott J; Bassett, David R; Swartz, Ann M

2004-07-01

Two methods of measuring physical activity (PA) were compared over a consecutive 7-day period among 25 adults (12 men and 13 women). Each day estimates of energy expended in light, moderate, vigorous, and total PA were derived from the simultaneous heart-rate motion sensor (HR+M) technique. At the end of the 7-day period participants completed the College Alumnus Questionnaire Physical Activity Index (CAQ-PAI) and results were compared with HR+M technique estimates. Correlations between the two methods in the four activity categories ranged from r=0.20 to r=0.47, with vigorous and total PA showing higher associations than light and moderate PA. Mean levels of PA (MET-minxwk(-1)) obtained using the two methods were similar in the moderate and vigorous categories, but individual differences were large. Energy expended in light PA was significantly underestimated on the CAQ-PAI, resulting in lower total activity scores on this questionnaire as compared with the HR+M. The CAQ-PAI accurately reflected mean moderate and vigorous activity in comparison with the HR+M technique. The results are consistent with other studies which have shown that physical activity questionnaires are better at assessing vigorous PA than ubiquitous light-moderate activities.

Real-time detection and monitoring of the drug resistance of single myeloid leukemia cells by diffused total internal reflection.

PubMed

Liang, L; Jin, Y X; Zhu, X Q; Zhou, F L; Yang, Y

2018-05-15

Real-time detection and monitoring of the drug resistance of single cells have important significance in clinical diagnosis and therapy. Traditional methods operate a number of times for each individual concentration, and innovation is required for the design of more simple and efficient manipulation platforms with necessary higher sensitivity. Here, we have developed a novel diffused total internal reflection (TIR) method to perform drug metabolism and cytotoxicity analysis of trapped myeloid leukemia cells. Molm-13 cells, a type of acute myeloid leukemia cell, were chosen and injected into the device and fittingly captured by cell traps. Differing from previous studies, a series of different concentrations of azelaic acid (AZA) drug could be used from 0 mM to 50 mM through convection and diffusion processes in a single chip, with each concentration region featuring 50 cells, with a total of 549 cell trapping units. Thanks to the high sensitivity of the TIR method, only cells with the same drug concentration could be illuminated in the detection process. By adjusting the incident angle, we could exactly detect and monitor the drug resistance of the cells using different drug concentrations and the experimental resolution of the drug concentration was as small as 5 mM. Images of the membrane integrity and morphology of the cells in the bright field were measured and we also monitored the cell viabilities in the dark field over 2 hours. The effects of AZA on the Molm-13 cells were explored in different concentrations at the single cell level. Compared with the results of the traditional MTT assay method, the experimental results are more simple and accurate. A cell death of 5% at an AZA concentration of 5 mM was observed after 30 minutes, while a concentration of 40 mM corresponded to a 98% cell death. The designed method in this study provides a novel toolkit to control and monitor drug resistance at the single cell level more easily with higher sensitivity and we believe it has significant potential application in single cell quality assessment and medicine analysis in clinical practice.

Effect of modulation of the particle size distributions in the direct solid analysis by total-reflection X-ray fluorescence

NASA Astrophysics Data System (ADS)

Fernández-Ruiz, Ramón; Friedrich K., E. Josue; Redrejo, M. J.

2018-02-01

The main goal of this work was to investigate, in a systematic way, the influence of the controlled modulation of the particle size distribution of a representative solid sample with respect to the more relevant analytical parameters of the Direct Solid Analysis (DSA) by Total-reflection X-Ray Fluorescence (TXRF) quantitative method. In particular, accuracy, uncertainty, linearity and detection limits were correlated with the main parameters of their size distributions for the following elements; Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Rb, Sr, Ba and Pb. In all cases strong correlations were finded. The main conclusion of this work can be resumed as follows; the modulation of particles shape to lower average sizes next to a minimization of the width of particle size distributions, produce a strong increment of accuracy, minimization of uncertainties and limit of detections for DSA-TXRF methodology. These achievements allow the future use of the DSA-TXRF analytical methodology for development of ISO norms and standardized protocols for the direct analysis of solids by mean of TXRF.

Polarization of the Radiation Reflected and Transmitted by the Earth's Atmosphere.

PubMed

Plass, G N; Kattawar, G W

1970-05-01

The polarization of the reflected and transmitted radiation is calculated for a realistic model of the earth's atmosphere at five wavelengths ranging from 0.27 micro to 1.67 micro. The single scattering matrix is calculated from the Mie theory for an aerosol size distribution appropriate for our atmosphere. The solar photons are followed through multiple collisions with the aerosols and the Rayleigh scattering centers in the atmosphere by a Monte Carlo method. The aerosol number density as well as the ratio of aerosol to Rayleigh scattering varies with height. The proportion of aerosol to Rayleigh scattering is adjusted for each wavelength; ozone absorption is included where appropriate. The polarization is presented as a function of the zenith and azimuthal angle for six values of the earth's albedo, two values of the solar zenith angle, and four values of the total aerosol concentration. In general the polarization decreases as the wavelength increases and as the total aerosol concentration increases (because of the increasing importance of aerosol scattering). In most situations the polarization is much more sensitive than the radiance to changes in the parameters which specify the atmosphere.

Elucidation of perovskite film micro-orientations using two-photon total internal reflectance fluorescence microscopy

DOE PAGES

Watson, Brianna R.; Yang, Bin; Xiao, Kai; ...

2015-07-29

The emergence of efficient hybrid organic-inorganic perovskite photovoltaic materials has caused the rapid development of a variety of preparation and processing techniques designed to maximize their performance. As processing methods continue to emerge, it is important to understand how the optical properties of these materials are affected on a microscopic scale. Here polarization resolved two-photon total internal reflectance microscopy (TIRFM) was used to probe changes in transition dipole moment orientation as a function of thermal annealing time in hybrid organic-inorganic lead iodide based perovskite (CH 3NH 3PbI 3) thin films on glass. These results show that as thermal annealing timemore » is increased the distribution of transition moments pointing out-of-plane decreases in favor of forming areas with increased in-plane orientations. As a result, it was also shown through the axial sensitivity of TIRFM that the surface topography is manifested in the signal intensity and can be used to survey aspects of morphology in coincidence with the optical properties of these films.« less

Application of micro-attenuated total reflectance Fourier transform infrared spectroscopy to ink examination in signatures written with ballpoint pen on questioned documents.

PubMed

Nam, Yun Sik; Park, Jin Sook; Lee, Yeonhee; Lee, Kang-Bong

2014-05-01

Questioned documents examined in a forensic laboratory sometimes contain signatures written with ballpoint pen inks; these signatures were examined to assess the feasibility of micro-attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy as a forensic tool. Micro-ATR FTIR spectra for signatures written with 63 ballpoint pens available commercially in Korea were obtained and used to construct an FTIR spectral database. A library-searching program was utilized to identify the manufacturer, blend, and model of each black ballpoint pen ink based upon their FTIR peak intensities, positions, and patterns in the spectral database. This FTIR technique was also successfully used in determining the sequence of homogeneous line intersections from the crossing lines of two ballpoint pen signatures. We have demonstrated with a set of sample documents that micro-ATR FTIR is a viable nondestructive analytical method that can be used to identify the origin of the ballpoint pen ink used to mark signatures. © 2014 American Academy of Forensic Sciences.

The study of genomic DNA adsorption and subsequent interactions using total internal reflection ellipsometry.

PubMed

Nabok, Alexei; Tsargorodskaya, Anna; Davis, Frank; Higson, Séamus P J

2007-10-31

The adsorption of genomic DNA and subsequent interactions between adsorbed and solvated DNA was studied using a novel sensitive optical method of total internal reflection ellipsometry (TIRE), which combines spectroscopic ellipsometry with surface plasmon resonance (SPR). Single strands of DNA of two species of fish (herring and salmon) were electrostatically adsorbed on top of polyethylenimine films deposited upon gold coated glass slides. The ellipsometric spectra were recorded and data fitting utilized to extract optical parameters (thickness and refractive index) of adsorbed DNA layers. The further adsorption of single stranded DNA from an identical source, i.e. herring ss-DNA on herring ss-DNA or salmon ss-DNA on salmon ss-DNA, on the surface was observed to give rise to substantial film thickness increases at the surface of about 20-21 nm. Conversely adsorption of DNA from alternate species, i.e. salmon ss-DNA on herring ss-DNA or herring ss-DNA on salmon ss-DNA, yielded much smaller changes in thickness of 3-5 nm. AFM studies of the surface roughness of adsorbed layers were in line with the TIRE data.

Infrared spectroscopy and spectroscopic imaging in forensic science.

PubMed

Ewing, Andrew V; Kazarian, Sergei G

2017-01-16

Infrared spectroscopy and spectroscopic imaging, are robust, label free and inherently non-destructive methods with a high chemical specificity and sensitivity that are frequently employed in forensic science research and practices. This review aims to discuss the applications and recent developments of these methodologies in this field. Furthermore, the use of recently emerged Fourier transform infrared (FT-IR) spectroscopic imaging in transmission, external reflection and Attenuated Total Reflection (ATR) modes are summarised with relevance and potential for forensic science applications. This spectroscopic imaging approach provides the opportunity to obtain the chemical composition of fingermarks and information about possible contaminants deposited at a crime scene. Research that demonstrates the great potential of these techniques for analysis of fingerprint residues, explosive materials and counterfeit drugs will be reviewed. The implications of this research for the examination of different materials are considered, along with an outlook of possible future research avenues for the application of vibrational spectroscopic methods to the analysis of forensic samples.

Performance analysis of higher mode spoof surface plasmon polariton for terahertz sensing

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

Yao, Haizi; Tu, Wanli; Zhong, Shuncong, E-mail: zhongshuncong@hotmail.com

2015-04-07

We investigated the spoof surface plasmon polaritons (SSPPs) on 1D grooved metal surface for terahertz sensing of refractive index of the filling analyte through a prism-coupling attenuated total reflection setup. From the dispersion relation analysis and the finite element method-based simulation, we revealed that the dispersion curve of SSPP got suppressed as the filling refractive index increased, which cause the coupling resonance frequency redshifting in the reflection spectrum. The simulated results for testing various refractive indexes demonstrated that the incident angle of terahertz radiation has a great effect on the performance of sensing. Smaller incident angle will result in amore » higher sensitive sensing with a narrower detection range. In the meanwhile, the higher order mode SSPP-based sensing has a higher sensitivity with a narrower detection range. The maximum sensitivity is 2.57 THz/RIU for the second-order mode sensing at 45° internal incident angle. The proposed SSPP-based method has great potential for high sensitive terahertz sensing.« less

Noninvasive spectral imaging of skin chromophores based on multiple regression analysis aided by Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Nishidate, Izumi; Wiswadarma, Aditya; Hase, Yota; Tanaka, Noriyuki; Maeda, Takaaki; Niizeki, Kyuichi; Aizu, Yoshihisa

2011-08-01

In order to visualize melanin and blood concentrations and oxygen saturation in human skin tissue, a simple imaging technique based on multispectral diffuse reflectance images acquired at six wavelengths (500, 520, 540, 560, 580 and 600nm) was developed. The technique utilizes multiple regression analysis aided by Monte Carlo simulation for diffuse reflectance spectra. Using the absorbance spectrum as a response variable and the extinction coefficients of melanin, oxygenated hemoglobin, and deoxygenated hemoglobin as predictor variables, multiple regression analysis provides regression coefficients. Concentrations of melanin and total blood are then determined from the regression coefficients using conversion vectors that are deduced numerically in advance, while oxygen saturation is obtained directly from the regression coefficients. Experiments with a tissue-like agar gel phantom validated the method. In vivo experiments with human skin of the human hand during upper limb occlusion and of the inner forearm exposed to UV irradiation demonstrated the ability of the method to evaluate physiological reactions of human skin tissue.

Use of visible and near infrared reflectance spectra to predict lipid peroxidation of light lamb meat and discriminate dam's feeding systems.

PubMed

Ripoll, G; Lobón, S; Joy, M

2018-09-01

Measurement of thiobarbituric acid reactive substances (TBARS) is a well-established method for determine lipid oxidation in meat. This assay, however, is time-consuming and generates undesired chemical waste. Dam's milk is the principal source of vitamins and provitamins that delay lipid oxidation of light lamb meat; these compounds are stored in the lamb's muscle tissue. Hence, lamb meat could be used to determine the origin of the dam's diet. The aim of this study is to evaluate Near-infrared reflectance spectroscopy (NIRS) as a tool for determining the lipid peroxidation of light lamb meat and differentiate the meat of light lambs according the diet of their dams during lactation (grazing alfalfa, lucerne, or fed a total mixed ration). NIRS using select wavelengths was able to detect the lipid oxidation of meat (TBARS method). NIRS can detect analytes at concentrations of parts per million. Moreover, the feed diets were discriminated successfully. Copyright © 2018 Elsevier Ltd. All rights reserved.

Recent results of synchrotron radiation induced total reflection X-ray fluorescence analysis at HASYLAB, beamline L

NASA Astrophysics Data System (ADS)

Streli, C.; Pepponi, G.; Wobrauschek, P.; Jokubonis, C.; Falkenberg, G.; Záray, G.; Broekaert, J.; Fittschen, U.; Peschel, B.

2006-11-01

At the Hamburger Synchrotronstrahlungslabor (HASYLAB), Beamline L, a vacuum chamber for synchrotron radiation-induced total reflection X-ray fluorescence analysis, is now available which can easily be installed using the adjustment components for microanalysis present at this beamline. The detector is now in the final version of a Vortex silicon drift detector with 50-mm 2 active area from Radiant Detector Technologies. With the Ni/C multilayer monochromator set to 17 keV extrapolated detection limits of 8 fg were obtained using the 50-mm 2 silicon drift detector with 1000 s live time on a sample containing 100 pg of Ni. Various applications are presented, especially of samples which are available in very small amounts: As synchrotron radiation-induced total reflection X-ray fluorescence analysis is much more sensitive than tube-excited total reflection X-ray fluorescence analysis, the sampling time of aerosol samples can be diminished, resulting in a more precise time resolution of atmospheric events. Aerosols, directly sampled on Si reflectors in an impactor were investigated. A further application was the determination of contamination elements in a slurry of high-purity Al 2O 3. No digestion is required; the sample is pipetted and dried before analysis. A comparison with laboratory total reflection X-ray fluorescence analysis showed the higher sensitivity of synchrotron radiation-induced total reflection X-ray fluorescence analysis, more contamination elements could be detected. Using the Si-111 crystal monochromator also available at beamline L, XANES measurements to determine the chemical state were performed. This is only possible with lower sensitivity as the flux transmitted by the crystal monochromator is about a factor of 100 lower than that transmitted by the multilayer monochromator. Preliminary results of X-ray absorption near-edge structure measurements for As in xylem sap from cucumber plants fed with As(III) and As(V) are reported. Detection limits of 170 ng/l of As in xylem sap were achieved.

Comparison of Attenuated Total Reflectance Mid-Infrared, Near Infrared, and 1H-Nuclear Magnetic Resonance Spectroscopies for the Determination of Coffee's Geographical Origin.

PubMed

Medina, Jessica; Caro Rodríguez, Diana; Arana, Victoria A; Bernal, Andrés; Esseiva, Pierre; Wist, Julien

2017-01-01

The sensorial properties of Colombian coffee are renowned worldwide, which is reflected in its market value. This raises the threat of fraud by adulteration using coffee grains from other countries, thus creating a demand for robust and cost-effective methods for the determination of geographical origin of coffee samples. Spectroscopic techniques such as Nuclear Magnetic Resonance (NMR), near infrared (NIR), and mid-infrared (mIR) have arisen as strong candidates for the task. Although a body of work exists that reports on their individual performances, a faithful comparison has not been established yet. We evaluated the performance of 1 H-NMR, Attenuated Total Reflectance mIR (ATR-mIR), and NIR applied to fraud detection in Colombian coffee. For each technique, we built classification models for discrimination by species ( C. arabica versus C. canephora (or robusta )) and by origin (Colombia versus other C. arabica ) using a common set of coffee samples. All techniques successfully discriminated samples by species, as expected. Regarding origin determination, ATR-mIR and 1 H-NMR showed comparable capacity to discriminate Colombian coffee samples, while NIR fell short by comparison. In conclusion, ATR-mIR, a less common technique in the field of coffee adulteration and fraud detection, emerges as a strong candidate, faster and with lower cost compared to 1 H-NMR and more discriminating compared to NIR.

Osmotic effects of polyethylene glycol.

PubMed

Schiller, L R; Emmett, M; Santa Ana, C A; Fordtran, J S

1988-04-01

Polyethylene glycol (PEG) has been used to increase the osmotic pressure of fluids used to cleanse the gastrointestinal tract. However, little is known about its osmotic activity. To investigate this activity systematically, solutions of PEG of differing molecular weights were made and subjected to measurement of osmolality by both freezing point depression and vapor pressure osmometry. Measured osmolality was increasingly greater than predicted from average molecular weight as PEG concentration increased. Measurement of sodium activity in NaCl/PEG solutions by means of an ion-selective electrode suggested that the higher than expected osmolality could be due in part to interactions that, in effect, sequestered water from the solution. Osmolality was consistently greater by freezing point osmometry than by vapor pressure osmometry. To determine which osmometry method reflected biologically relevant osmolality, normal subjects underwent steady-state total gut perfusion with an electrolyte solution containing 105 g/L of PEG 3350. This produced rectal effluent that was hypertonic by freezing point osmometry but isotonic by vapor pressure osmometry. Assuming that luminal fluid reaches osmotic equilibrium with plasma during total gut perfusion, this result suggests that the vapor pressure osmometer accurately reflects the biologically relevant osmolality of intestinal contents. We conclude that PEG exerts more of an osmotic effect than would be predicted from its molecular weight. This phenomenon may reflect interactions between PEG and water molecules that alter the physical chemistry of the solution and sequester water from the solution.

Determination of trans Fat in Selected Fast Food Products and Hydrogenated Fats of India Using Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy.

PubMed

Khan, Mohd Umar; Hassan, Mohammad Fahimul; Rauf, Abdul

2017-01-01

This paper reports the application of a simple and rapid method for the determination of trans fatty acid (TFA) content in some of the selected Indian fast food products and hydrogenated fats using Fourier transform infrared (FTIR) spectroscopy in conjunction with second derivative procedure. FTIR spectroscopy has been successfully applied to trans measurement using the absorbance bands at or near 966 cm -1 in the FTIR spectra. It was found from the analysis that TFA content of fast food product was ranging from 1.57% to 3.83% of the total fat while for hydrogenated fats, comparatively large quantity of TFA was detected in the range of 3.31% to 4.73%. Since GC-FID is most widely used method for the determination of fatty acid (FA) composition, this method was used for the sake of comparison. Value of regression coefficient was found very close to one (0.99503) with standard deviation of 0.10247 showing a good agreement between GC-FID and proposed ATR-FTIR method.

Solid-state laser pumping with a planar compound parabolic concentrator.

PubMed

Panteli, D V; Pani, B M; Beli, L Z

1997-10-20

A novel solid-state laser-pumping scheme is proposed that combines a reflective lamp chamber and a compound parabolic concentrator (CPC) as a light guide. The CPC is made of a transparent material of high refractive index, and light is guided by the total internal reflection, with drastically reduced reflection losses. Material is chosen so that the absorption losses are minimized in the pumping wavelength range. The lamp chamber is designed with the principles of nonimaging optics, which ensures that the radiation is efficiently transferred from the lamp to the input aperture of the CPC. The pumping efficiency was first estimated theoretically, which gave us enough justification for the more accurate calculations with ray tracing. Single as well as multiple pumping cavities are discussed. New pumping geometry results in significantly increased pumping efficiency compared with conventional geometries. Also the lamp and the laser rod are separated, leading to reduced thermal load. We found that the proposed pumping method is also applicable to diode-pumped lasers.

Simulation of Triple Oxidation Ditch Wastewater Treatment Process

NASA Astrophysics Data System (ADS)

Yang, Yue; Zhang, Jinsong; Liu, Lixiang; Hu, Yongfeng; Xu, Ziming

2010-11-01

This paper presented the modeling mechanism and method of a sewage treatment system. A triple oxidation ditch process of a WWTP was simulated based on activated sludge model ASM2D with GPS-X software. In order to identify the adequate model structure to be implemented into the GPS-X environment, the oxidation ditch was divided into several completely stirred tank reactors depended on the distribution of aeration devices and dissolved oxygen concentration. The removal efficiency of COD, ammonia nitrogen, total nitrogen, total phosphorus and SS were simulated by GPS-X software with influent quality data of this WWTP from June to August 2009, to investigate the differences between the simulated results and the actual results. The results showed that, the simulated values could well reflect the actual condition of the triple oxidation ditch process. Mathematical modeling method was appropriate in effluent quality predicting and process optimizing.

Salivary analytes in patients with oral squamous cell carcinoma.

PubMed

Fuchs, Petra Nola; Rogić, Dunja; Vidović-Juras, Danica; Susić, Mato; Milenović, Aleksandar; Brailo, Vlaho; Boras, Vanja Vucićević

2011-06-01

Literature data indicates that measurement of certain salivary constituents might serve as a useful diagnostic/prognostic tool in the patients with oral squamous cell carcinoma (OSCC). In 24 patients with OSCC (60 +/- 2.5 yrs) and in 24 controls (24 +/- 3.7 yrs) we have determined levels of salivary magnesium, calcium, copper, chloride, phosphate, potassium, sodium, total proteins and amylase. Sodium, potassium and chloride were determined by indirect potentiometry whereas copper, magnesium and phosphate were determined by atomic absorption spectrophotometry. Total proteins were determined by pyrogalol colorimetric method. Amylase levels were determined by continued colorimetric method. Statistical analysis was performed by use of chi2 test and Spearman's correlation test. The results of this study indicate that the concentrations of sodium and chloride were significantly elevated in patients with OSCC when compared to the controls. However, level of total protein was significantly decreased when compared to the healthy controls. Furthermore, there was a negative correlation between alcohol consumption and total protein concentration in patients with oral carcinoma. We might conclude that in patients with OSCC increased salivary sodium and chloride might reflect their overall dehydration status due to alcohol consumption rather than consequence of OSCC itself.

Validation of the long-term assessment of hypothalamic-pituitary-adrenal activity in rats using hair corticosterone as a biomarker.

PubMed

Scorrano, Fabrizio; Carrasco, Javier; Pastor-Ciurana, Jordi; Belda, Xavier; Rami-Bastante, Alicia; Bacci, Maria Laura; Armario, Antonio

2015-03-01

The evaluation of chronic activity of the hypothalamic-pituitary-adrenal (HPA) axis is critical for determining the impact of chronic stressful situations. However, current methods have important limitations. The potential use of hair glucocorticoids as a noninvasive retrospective biomarker of long-term HPA activity is gaining acceptance in humans and wild animals. However, there is no study examining hair corticosterone (HC) in laboratory animals. The present study validates a method for measuring HC in rats and demonstrates that it properly reflects chronic HPA activity. The HC concentration was similar in male and female rats, despite higher total plasma corticosterone levels in females, tentatively suggesting that it reflects free rather than total plasma corticosterone. Exposure of male rats to 2 different chronic stress protocols (chronic immobilization and chronic unpredictable stress) resulted in similarly higher HC levels compared to controls (1.8-fold). HC also increased after a mild chronic stressor (30 min daily restraint). Chronic administration of 2 different doses of a long-acting ACTH preparation dramatically increased HC (3.1- and 21.5-fold, respectively), demonstrating that a ceiling effect in HC accumulation is unlikely under other more natural conditions. Finally, adrenalectomy significantly reduced HC. In conclusion, HC measurement in rats appears appropriate to evaluate integrated chronic changes in circulating corticosterone. © FASEB.

Reflection-Based Learning for Professional Ethical Formation.

PubMed

Branch, William T; George, Maura

2017-04-01

One way practitioners learn ethics is by reflecting on experience. They may reflect in the moment (reflection-in-action) or afterwards (reflection-on-action). We illustrate how a teaching clinician may transform relationships with patients and teach person-centered care through reflective learning. We discuss reflective learning pedagogies and present two case examples of our preferred method, guided group reflection using narratives. This method fosters moral development alongside professional identity formation in students and advanced learners. Our method for reflective learning addresses and enables processing of the most pressing ethical issues that learners encounter in practice. © 2017 American Medical Association. All Rights Reserved.

Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) Data Products User's Guide

NASA Technical Reports Server (NTRS)

McPeters, Richard D.; Bhartia, P. K.; Krueger, Arlin J.; Herman, Jay R.; Schlesinger, Barry M.; Wellemeyer, Charles G.; Seftor, Colin J.; Jaross, Glen; Taylor, Steven L.; Swissler, Tom;

Quantification of tissue oxygenation levels using diffuse reflectance spectroscopy

NASA Astrophysics Data System (ADS)

B. S., Suresh Anand; N., Sujatha

2011-08-01

Tumor growth is characterized by increased metabolic activity. The light absorption profile of hemoglobin in dysplastic tissue is different from a normal tissue. Neovascularization is a hallmark of many diseases and can serve as a predictive biomarker for the detection of cancers. Spectroscopic techniques can provide information about the metabolic and morphological changes related to the progression of neoplasia. Diffuse reflectance spectroscopy (DRS) measures the absorption and scattering properties of a biological tissue and this method can provide clinically useful information for the early diagnosis of epithelial precancers. We used tissue simulating phantoms with absorbing and scattering molecules for the determination of total hemoglobin concentration, hemoglobin oxygen saturation and intensity difference between the deoxy and oxy hemoglobin bands. The results show promising approach for the differentiating normal and malignant states of a tissue.

Effect of different drying methods on the composition of steviol glycosides in Stevia rebaudiana Bertoni leaves

NASA Astrophysics Data System (ADS)

Aranda-González, Irma; Betancur-Ancona, David; Chel-Guerrero, Luis; Moguel-Ordóñez, Yolanda

2017-01-01

Drying techniques can modify the composition of certain plant compounds. Therefore, the aim of the study was to assess the effect of different drying methods on steviol glycosides in Stevia rebaudiana Bertoni leaves. Four different drying methods were applied to Stevia rebaudiana Bertoni leaves, which were then subjected to aqueous extraction. Radiation or convection drying was performed in stoves at 60°C, whereas shade or sun drying methods were applied at 29.7°C and 70% of relative humidity. Stevioside, rebaudioside A, rebaudioside B, rebaudioside C, rebaudioside D, dulcoside A, and steviolbioside were quantified by a validated HPLC method. Among steviol glycosides, the content (g 100 g-1 dry basis) of stevioside, rebaudioside A, rebaudioside B, and rebaudioside C varied according to the drying method. The total glycoside content was higher in sun-dried samples, with no significant differences compared to shade or convection drying, whereas radiation drying adversely affected the content of rebaudioside A and rebaudioside C (p <0.01) and was therefore a method lowering total glycoside content. The effect of the different drying methods was also reflected in the proportion of the sweetener profile. Convection drying could be suitable for modern food processing industries while shadow or sun drying may be a low-cost alternative for farmers.

Reduction of shading-derived artifacts in skin chromophore imaging without measurements or assumptions about the shape of the subject

NASA Astrophysics Data System (ADS)

Yoshida, Kenichiro; Nishidate, Izumi; Ojima, Nobutoshi; Iwata, Kayoko

2014-01-01

To quantitatively evaluate skin chromophores over a wide region of curved skin surface, we propose an approach that suppresses the effect of the shading-derived error in the reflectance on the estimation of chromophore concentrations, without sacrificing the accuracy of that estimation. In our method, we use multiple regression analysis, assuming the absorbance spectrum as the response variable and the extinction coefficients of melanin, oxygenated hemoglobin, and deoxygenated hemoglobin as the predictor variables. The concentrations of melanin and total hemoglobin are determined from the multiple regression coefficients using compensation formulae (CF) based on the diffuse reflectance spectra derived from a Monte Carlo simulation. To suppress the shading-derived error, we investigated three different combinations of multiple regression coefficients for the CF. In vivo measurements with the forearm skin demonstrated that the proposed approach can reduce the estimation errors that are due to shading-derived errors in the reflectance. With the best combination of multiple regression coefficients, we estimated that the ratio of the error to the chromophore concentrations is about 10%. The proposed method does not require any measurements or assumptions about the shape of the subjects; this is an advantage over other studies related to the reduction of shading-derived errors.

Reconstruction of structural damage based on reflection intensity spectra of fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Huang, Guojun; Wei, Changben; Chen, Shiyuan; Yang, Guowei

2014-12-01

We present an approach for structural damage reconstruction based on the reflection intensity spectra of fiber Bragg gratings (FBGs). Our approach incorporates the finite element method, transfer matrix (T-matrix), and genetic algorithm to solve the inverse photo-elastic problem of damage reconstruction, i.e. to identify the location, size, and shape of a defect. By introducing a parameterized characterization of the damage information, the inverse photo-elastic problem is reduced to an optimization problem, and a relevant computational scheme was developed. The scheme iteratively searches for the solution to the corresponding direct photo-elastic problem until the simulated and measured (or target) reflection intensity spectra of the FBGs near the defect coincide within a prescribed error. Proof-of-concept validations of our approach were performed numerically and experimentally using both holed and cracked plate samples as typical cases of plane-stress problems. The damage identifiability was simulated by changing the deployment of the FBG sensors, including the total number of sensors and their distance to the defect. Both the numerical and experimental results demonstrate that our approach is effective and promising. It provides us with a photo-elastic method for developing a remote, automatic damage-imaging technique that substantially improves damage identification for structural health monitoring.

Effectiveness of Cognitive Processing Therapy and Prolonged Exposure in the Department of Veterans Affairs.

PubMed

Rutt, Benjamin T; Oehlert, Mary E; Krieshok, Thomas S; Lichtenberg, James W

2018-04-01

Objective This study evaluated the effectiveness of cognitive processing therapy and prolonged exposure in conditions reflective of current clinical practice within the Veterans Health Administration. Method This study involved a retrospective review of 2030 charts. A total of 750 veterans from 10 U.S. states who received cognitive processing therapy or prolonged exposure in individual psychotherapy were included in the study (participants in cognitive processing therapy, N = 376; participants in prolonged exposure, N = 374). The main dependent variable was self-reported posttraumatic stress disorder symptoms as measured by total scores on the Posttraumatic Stress Disorder Checklist. The study used multilevel modeling to evaluate the absolute and relative effectiveness of both treatments and determine the relationship between patient-level variables and total Posttraumatic Stress Disorder Checklist scores during treatment. Results Cognitive processing therapy and prolonged exposure were equally effective at reducing total Posttraumatic Stress Disorder Checklist scores. Veterans who completed therapy reported significantly larger reductions in the Posttraumatic Stress Disorder Checklist than patients who did not complete therapy. There were no significant differences in the improvement of posttraumatic stress disorder symptoms with respect to age and three racial/ethnic groups (Caucasian, African American, and Hispanic). Conclusions Cognitive processing therapy and prolonged exposure were shown to be effective in conditions highly reflective of clinical practice and with a highly diverse sample of veterans. Challenges related to dropout from trauma focused therapy should continue to be researched.

Plasmonically amplified bioassay - Total internal reflection fluorescence vs. epifluorescence geometry.

PubMed

Hageneder, Simone; Bauch, Martin; Dostalek, Jakub

2016-08-15

This paper investigates plasmonic amplification in two commonly used optical configurations for fluorescence readout of bioassays - epifluorescence (EPF) and total internal reflection fluorescence (TIRF). The plasmonic amplification in the EPF configuration was implemented by using crossed gold diffraction grating and Kretschmann geometry of attenuated total reflection method (ATR) was employed in the TIRF configuration. Identical assay, surface architecture for analyte capture, and optics for the excitation, collection and detection of emitted fluorescence light intensity were used in both TIRF and EPF configurations. Simulations predict that the crossed gold diffraction grating (EPF) can amplify the fluorescence signal by a factor of 10(2) by the combination of surface plasmon-enhanced excitation and directional surface plasmon-coupled emission in the red part of spectrum. This factor is about order of magnitude higher than that predicted for the Kretschmann geometry (TIRF) which only took advantage of the surface plasmon-enhanced excitation. When applied for the readout of sandwich interleukin 6 (IL-6) immunoassay, the plasmonically amplified EPF geometry designed for Alexa Fluor 647 labels offered 4-times higher fluorescence signal intensity compared to TIRF. Interestingly, both geometries allowed reaching the same detection limit of 0.4pM despite of the difference in the fluorescence signal enhancement. This is attributed to inherently lower background of fluorescence signal for TIRF geometry compared to that for EPF which compensates for the weaker fluorescence signal enhancement. The analysis of the inflammation biomarker IL-6 in serum at medically relevant concentrations and the utilization of plasmonic amplification for the fluorescence measurement of kinetics of surface affinity reactions are demonstrated for both EPF and TIRF readout. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Analysis of nutrition-relevant trace elements in human blood and serum by means of total reflection X-ray fluorescence (TXRF) spectroscopy

NASA Astrophysics Data System (ADS)

Stosnach, Hagen; Mages, Margarete

2009-04-01

In clinical service laboratories, one of the most common analytical tasks with regard to inorganic traces is the determination of the nutrition-relevant elements Fe, Cu, Zn, and Se. Because of the high numbers of samples and the commercial character of these analyses, a time-consuming sample preparation must be avoided. In this presentation, the results of total reflection X-ray fluorescence measurements with a low-power system and different sample preparation procedures are compared with those derived from analysis with common methods like Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The results of these investigations indicate that the optimal total reflection X-ray fluorescence analysis of the nutrition-relevant elements Fe, Cu, Zn, and Se can be performed by preparing whole blood and serum samples after dilution with ultrapure water and transferring 10 μl of internally standardized sample to an unsiliconized quartz glass sample carrier with subsequent drying in a laboratory oven. Suitable measurement time was found to be 600 s. The enhanced sample preparation by means of microwave or open digestion, in parts combined with cold plasma ashing, led to an improvement of detection limits by a factor of 2 for serum samples while for whole blood samples an improvement was only observed for samples prepared by means of microwave digestion. As the matrix elements P, S, Cl, and for whole blood Fe have a major influence on the detection limits, most probably a further enhancement of analytical quality requires the removal of the organic matrix. However, for the routine analysis of the nutrition-relevant elements, the dilution preparation was found to be sufficient.

Determination of As concentration in earthworm coelomic fluid extracts by total-reflection X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Allegretta, Ignazio; Porfido, Carlo; Panzarino, Onofrio; Fontanella, Maria Chiara; Beone, Gian Maria; Spagnuolo, Matteo; Terzano, Roberto

2017-04-01

Earthworms are often used as sentinel organisms to study As bioavailability in polluted soils. Arsenic in earthworms is mainly sequestrated in the coelomic fluids whose As content can therefore be used to asses As bioavalability. In this work, a method for determining As concentration in coelomic fluid extracts using total-reflection X-ray fluorescence spectrometry (TXRF) is presented. For this purpose coelomic fluid extracts from earthworms living in three polluted soils and one non-polluted (control) soil have been collected and analysed. A very simple sample preparation was implemented, consisting of a dilution of the extracts with polyvinyl alcohol (PVA) using a 1:8 ratio and dropwise deposition of the sample on the reflector. A detection limit of 0.2 μg/l and quantification limit of 0.6 μg/l was obtained in the diluted samples, corresponding to 2 μg/l and 6 μg/l in the coelomic fluid extracts, respectively. This allowed to quantify As concentration in coelomic fluids extracted from earthworms living in soils polluted with As at concentrations higher than 20 mg/kg (considered as a pollution threshold for agricultural soils). The TXRF method has been validated by comparison with As concentrations in standards and by analysing the same samples by ICP-MS, after acid digestion of the sample. The low limit of detection, the proven reliability of the method and the little sample preparation make TXRF a suitable, cost-efficient and "green" technique for the analysis of As in earthworm coelomic fluid extracts for bioavailability studies.

Computational assessment of model-based wave separation using a database of virtual subjects.

PubMed

Hametner, Bernhard; Schneider, Magdalena; Parragh, Stephanie; Wassertheurer, Siegfried

2017-11-07

The quantification of arterial wave reflection is an important area of interest in arterial pulse wave analysis. It can be achieved by wave separation analysis (WSA) if both the aortic pressure waveform and the aortic flow waveform are known. For better applicability, several mathematical models have been established to estimate aortic flow solely based on pressure waveforms. The aim of this study is to investigate and verify the model-based wave separation of the ARCSolver method on virtual pulse wave measurements. The study is based on an open access virtual database generated via simulations. Seven cardiac and arterial parameters were varied within physiological healthy ranges, leading to a total of 3325 virtual healthy subjects. For assessing the model-based ARCSolver method computationally, this method was used to perform WSA based on the aortic root pressure waveforms of the virtual patients. Asa reference, the values of WSA using both the pressure and flow waveforms provided by the virtual database were taken. The investigated parameters showed a good overall agreement between the model-based method and the reference. Mean differences and standard deviations were -0.05±0.02AU for characteristic impedance, -3.93±1.79mmHg for forward pressure amplitude, 1.37±1.56mmHg for backward pressure amplitude and 12.42±4.88% for reflection magnitude. The results indicate that the mathematical blood flow model of the ARCSolver method is a feasible surrogate for a measured flow waveform and provides a reasonable way to assess arterial wave reflection non-invasively in healthy subjects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Measuring ionospheric movements using totally reflected radio waves

NASA Astrophysics Data System (ADS)

Sadler, Elaine M.; Whitehead, J. D.; From, W. R.

1988-02-01

It is shown that for radio waves of a particular frequency reflected totally from the ionosphere the effect of refraction as well as reflection can be simulated by an effective reflecting surface. This mirror-like surface will give the correct angle of arrival and Doppler shift for all radars operating at this frequency. It is theoretically possible for the effective reflecting surface to be folded back on itself, but this is unlikely except for F-region echoes refracted by sporadic E-clouds. If the surface is not folded and exists everywhere, it is always possible to describe its motion and change in terms of wave undulations. Experimental data for F-region echoes show that these wave undulations are very dispersive. However, the matching between the best fitting model and the experimental data is worse than expected for reasons we do not understand.

Measuring ionospheric movements using totally reflected radio waves

NASA Astrophysics Data System (ADS)

From, W. R.; Sadler, Elaine M.; Whitehead, J. D.

1988-02-01

It is shown that for radio waves of a particular frequency reflected totally from the ionosphere the effect of refraction as well as reflection can be simulated by an effective reflecting surface. This mirrorlike surface will give the correct angle of arrival and Doppler shift for all radars operating at this frequency. It is theoretically possible for the effective reflecting surface to be folded back on itself, but this is unlikely except for F-region echoes refracted by sporadic E-clouds. If the surface is not folded and exists everywhere, it is always possible to describe its motion and change in terms of wave undulations. Experimental data for F-region echoes show that these wave undulations are very dispersive. However, the matching between the best fitting model and the experimental data is worse than expected for reasons we do not understand.

Accuracy improvement in measurement of arterial wall elasticity by applying pulse inversion to phased-tracking method

NASA Astrophysics Data System (ADS)

Miyachi, Yukiya; Arakawa, Mototaka; Kanai, Hiroshi

2018-07-01

In our studies on ultrasonic elasticity assessment, minute change in the thickness of the arterial wall was measured by the phased-tracking method. However, most images in carotid artery examinations contain multiple-reflection noise, making it difficult to evaluate arterial wall elasticity precisely. In the present study, a modified phased-tracking method using the pulse inversion method was examined to reduce the influence of the multiple-reflection noise. Moreover, aliasing in the harmonic components was corrected by the fundamental components. The conventional and proposed methods were applied to a pulsated tube phantom mimicking the arterial wall. For the conventional method, the elasticity was 298 kPa without multiple-reflection noise and 353 kPa with multiple-reflection noise on the posterior wall. That of the proposed method was 302 kPa without multiple-reflection noise and 297 kPa with multiple-reflection noise on the posterior wall. Therefore, the proposed method was very robust against multiple-reflection noise.

Calculation of vitrinite reflectance from thermal histories: A comparison of some methods

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

Morrow, D.W.; Issler, D.R.

1993-04-01

Vitrinite reflectance values (%R[sub o]) calculated from commonly used methods are compared with respect to time invariant temperatures and constant heating rates. Two monofunctional methods, one involving a time-temperature index to vitrinite reflectance correlation (TTI-%R[sub o]) to depth correlation, yield vitrinite reflectance values that are similar to those calculated by recently published Arrhenius-based methods, such as EASY%R[sub o]. The approximate agreement between these methods supports the perception that the EASY%R[sub o] algorithm is the most accurate method for the prediction of vitrinite reflectances throughout the range of organic maturity normally encountered. However, calibration of these methods against vitrinite reflectance datamore » from two basin sequences with well-documented geologic histories indicates that, although the EASY%R[sub o] method has wide applicability, it slightly overestimates vitrinite reflectances in strata of low to medium maturity up to a %R[sub o] value of 0.9%. The two monofunctional methods may be more accurate for prediction of vitrinite reflectances in similar sequences of low maturity. An older, but previously widely accepted TTI-%R[sub O] correlation consistently overestimates vitrinite reflectances with respect to other methods. Underestimation of paleogeothermal gradients in the original calibration of time-temperature history to vitrinite reflectance may have introduced a systematic bias to the TTI-%R[sub o] correlation used in this method. Also, incorporation of TAI (thermal alteration index) data and its conversion to %R[sub o]-equivalent values may have introduced inaccuracies. 36 refs., 7 figs.« less

Near-peer role modeling: Can fourth-year medical students, recognized for their humanism, enhance reflection among second-year students in a physical diagnosis course?

PubMed

McEvoy, Mimi; Pollack, Staci; Dyche, Lawrence; Burton, William

2016-01-01

Humanism is cultivated through reflection and self-awareness. We aimed to employ fourth-year medical students, recognized for their humanism, to facilitate reflective sessions for second-year medical students with the intention of positively influencing reflective process toward humanistic development. A total of 186 students were randomly assigned to one of three comparison arms: eight groups of eight students (64 students) were facilitated by a fourth-year student who was a Gold Humanism Honor Society member (GHHS); eight groups (64 students) by a volunteer non-GHHS student; and seven groups (58 students) were non-facilitated. Before sessions, second-year students set learning goals concerning interactions with patients; fourth-year students received training materials on facilitation. Groups met twice during their 10 clinical site visits. At the last session, students completed a reflective assignment on their goal progress. Comparative mixed method analyses were conducted among the three comparison arms on reflection (reflective score on in-session assignment) and session satisfaction (survey) in addition to a thematic analysis of responses on the in-session assignment. We found significant differences among all three comparison arms on students' reflective scores (p=0.0003) and satisfaction (p=0.0001). T-tests comparing GHHS- and non-GHHS-facilitated groups showed significantly higher mean reflective scores for GHHS-facilitated groups (p=0.033); there were no differences on session satisfaction. Thematic analysis of students' reflections showed attempts at self-examination, but lacked depth in addressing emotions. There was a common focus on achieving comfort and confidence in clinical skills performance. Near peers, recognized for their humanism, demonstrated significant influence in deepening medical students' reflections surrounding patient interactions or humanistic development. Overall, students preferred facilitated to non-facilitated peer feedback forums. This model holds promise for enhancing self-reflection in medical education, but needs further exploration to determine behavioral effects.

LANDSAT inventory of surface-mined areas using extendible digital techniques

NASA Technical Reports Server (NTRS)

Anderson, A. T.; Schultz, D. T.; Buchman, N.

1975-01-01

Multispectral LANDSAT imagery was analyzed to provide a rapid and accurate means of identification, classification, and measurement of strip-mined surfaces in Western Maryland. Four band analysis allows distinction of a variety of strip-mine associated classes, but has limited extendibility. A method for surface area measurements of strip mines, which is both geographically and temporally extendible, has been developed using band-ratioed LANDSAT reflectance data. The accuracy of area measurement by this method, averaged over three LANDSAT scenes taken between September 1972 and July 1974, is greater than 93%. Total affected acreage of large (50 hectare/124 acre) mines can be measured to within 1.0%.

Antimicrobial Activities of Silver Nanoparticles Synthesized by Using Water Extract of Arnicae anthodium.

PubMed

Dobrucka, Renata; Długaszewska, Jolanta

2015-06-01

Green synthesis of nanoparticles has gained significant importance in recent years and has become the one of the most preferred methods. Also, green synthesis of nanoparticles is valuable branch of nanotechnology. Plant extracts are eco-friendly and can be an economic option for synthesis of nanoparticles. This study presents method the synthesis of silver nanoparticles using water extract of Arnicae anthodium. Formation of silver nanoparticles was confirmed by UV-visble spectroscopy, Fourier transform infrared spectroscopy and total reflection X-ray fluorescence analysis. The morphology of the synthesized silver nanoparticles was verified by SEM-EDS. The obtained silver nanoparticles were used to study their antimicrobial activity.

Total internal reflection optical switch using the reverse breakdown of a pn junction in silicon.

PubMed

Kim, Jong-Hun; Park, Hyo-Hoon

2015-11-01

We demonstrate a new type of silicon total-internal-reflection optical switch with a simple pn junction functioning both as a reflector and a heater. The reflector is placed between asymmetrically y-branched multimode waveguides with an inclination angle corresponding to half of the branch angle. When the reflector is at rest, incident light is reflected in accordance to the refractive index difference due to the plasma dispersion effect of the pre-doped carriers. Switching to the transmission state is attained under a reverse breakdown of the pn junction by the thermo-optic effect which smears the refractive index difference. From this switching scheme, we confirmed the switching operation with a shallow total-internal-reflection region of 1 μm width. At a 6° branch angle, an extinction ratio of 12 dB and an insertion loss of -4.2  dB are achieved along with a thermal heating power of 151.5 mW.

Revisit: A Surprising Demonstration of Total Internal Reflection

ERIC Educational Resources Information Center

Lee, Jiwon; Cha, Yu Wha; Jung, Yeon Su; Oh, Eun Ju; Moon, Ye Lin; Kim, Jung Bog

2016-01-01

Melton demonstrated a surprising disappearance using total internal reflection. When he put a Florence flask filled with marbles into a water tank and looked straight down from directly above the flask, he was only able to see marbles above a certain water level. When he added more water into the tank above the top line of the marbles, all of the…

Characterization of southern yellow pine bark layers by Attenuated Total Reflectance (ATR) and Fourier Transform Infrared (FT-IR) Spectroscopy

Treesearch

Thomas L. Eberhardt

2009-01-01

The outer bark (rhytidome) of the southern yellow pines is a complex structure comprised of alternating layers of obliterated phloem and periderm tissues, with the latter comprised of three layers, those being phellem, phellogen, and phelloderm. An attenuated total reflectance (ATR) sampling accessory, coupled with a Fourier transform infrared (FTIR) spectrometer,...

Poultry Consumption and Arsenic Exposure in the U.S. Population

PubMed Central

Nigra, Anne E.; Nachman, Keeve E.; Love, David C.; Grau-Perez, Maria; Navas-Acien, Ana

2016-01-01

Background: Arsenicals (roxarsone and nitarsone) used in poultry production likely increase inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and roxarsone or nitarsone concentrations in poultry meat. However, the association between poultry intake and exposure to these arsenic species, as reflected in elevated urinary arsenic concentrations, is unknown. Objectives: Our aim was to evaluate the association between 24-hr dietary recall of poultry consumption and arsenic exposure in the U.S. population. We hypothesized first, that poultry intake would be associated with higher urine arsenic concentrations and second, that the association between turkey intake and increased urine arsenic concentrations would be modified by season, reflecting seasonal use of nitarsone. Methods: We evaluated 3,329 participants ≥ 6 years old from the 2003–2010 National Health and Nutrition Examination Survey (NHANES) with urine arsenic available and undetectable urine arsenobetaine levels. Geometric mean ratios (GMR) of urine total arsenic and DMA were compared across increasing levels of poultry intake. Results: After adjustment, participants in the highest quartile of poultry consumption had urine total arsenic 1.12 (95% CI: 1.04, 1.22) and DMA 1.13 (95% CI: 1.06, 1.20) times higher than nonconsumers. During the fall/winter, participants in the highest quartile of turkey intake had urine total arsenic and DMA 1.17 (95% CI: 0.99, 1.39; p-trend = 0.02) and 1.13 (95% CI: 0.99, 1.30; p-trend = 0.03) times higher, respectively, than nonconsumers. Consumption of turkey during the past 24 hr was not associated with total arsenic or DMA during the spring/summer. Conclusions: Poultry intake was associated with increased urine total arsenic and DMA in NHANES 2003–2010, reflecting arsenic exposure. Seasonally stratified analyses by poultry type provide strong suggestive evidence that the historical use of arsenic-based poultry drugs contributed to arsenic exposure in the U.S. population. Citation: Nigra AE, Nachman KE, Love DC, Grau-Perez M, Navas-Acien A. 2017. Poultry consumption and arsenic exposure in the U.S. population. Environ Health Perspect 125:370–377; http://dx.doi.org/10.1289/EHP351 PMID:27735790

Systematic considerations for a multicomponent pharmacokinetic study of Epimedii wushanensis herba: From method establishment to pharmacokinetic marker selection.

PubMed

Wang, Caihong; Wu, Caisheng; Zhang, Jinlan; Jin, Ying

2015-04-15

Prenylflavonoids are major active components of Epimedii wushanensis herba (EWH). The global pharmacokinetics of prenylflavonoids are unclear, as these compounds yield multiple, often unidentified metabolites. This study successfully elucidated the pharmacokinetic profiles of EWH extract and five EWH-derived prenylflavonoid monomers in rats. The study was a comprehensive analysis of metabolic pathways and pharmacokinetic markers. Major plasma compounds identified after oral administration of EWH-derived prototypes or extract included: (1) prenylflavonoid prototypes, (2) deglycosylated products, and (3) glucuronide conjugates. To select appropriate EWH-derived pharmacokinetic markers, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established to simultaneously monitor 14 major compounds in unhydrolyzed plasma and 10 potential pharmacokinetic markers in hydrolyzed plasma. The pharmacokinetic profiles indicated that the glucuronide conjugates of icaritin were the principle circulating metabolites and that total icaritin accounted for ∼99% of prenylflavonoid exposure after administration of EWH-derived materials to rats. To further investigate icaritin as a prospective pharmacokinetic marker, correlation analysis was performed between total icaritin and its glucuronide conjugates, and a strong correlation (r > 0.5) was found, indicating that total icaritin content accurately reflected changes in the exposure levels of the glucuronide conjugates over time. Therefore, icaritin is a sufficient pharmacokinetic marker for evaluating dynamic prenylflavonoid exposure levels. Next, a mathematical model was developed based on the prenylflavonoid content of EWH and the exposure levels in rats, using icaritin as the pharmacokinetic marker. This model accurately predicted exposure levels in vivo, with similar predicted vs. experimental area under the curve (AUC)(0-96 h) values for total icaritin (24.1 vs. 32.0 mg/L h). Icaritin in hydrolyzed plasma can be used as a pharmacokinetic marker to reflect prenylflavonoid exposure levels, as well as the changes over time of its glucuronide conjugates. Crown Copyright © 2015. Published by Elsevier GmbH. All rights reserved.

Bridging theory and practice: Mixed methods approach to instruction of law and ethics within the pharmaceutical sciences.

PubMed

Wilby, Kyle John; Nasr, Ziad Ghantous

2016-11-01

Background: Professional responsibilities are guided by laws and ethics that must be introduced and mastered within pharmaceutical sciences training. Instructional design to teaching typically introduces concepts in a traditional didactic approach and requires student memorization prior to application within practice settings. Additionally, many centers rely on best practices from abroad, due to lack of locally published laws and guidance documents. Objectives: The aim of this paper was to summarize and critically evaluate a professional skills laboratory designed to enhance learning through diversity in instructional methods relating to pharmacy law and best practices regarding narcotics, controlled medications, and benzodiazepines. Setting: This study took place within the Professional Skills Laboratory at the College of Pharmacy at Qatar University. Method: A total of 25 students participated in a redesigned laboratory session administered by a faculty member, clinical lecturer, teaching assistant, and a professional skills laboratory technician. The laboratory consisted of eight independent stations that students rotated during the 3-h session. Stations were highly interactive in nature and were designed using non-traditional approaches such as charades, role-plays, and reflective drawings. All stations attempted to have students relate learned concepts to practice within Qatar. Main outcome measures: Student perceptions of the laboratory were measured on a post-questionnaire and were summarized descriptively. Using reflection and consensus techniques, two faculty members completed a SWOC (Strengths, Weaknesses, Opportunities, and Challenges) analysis in preparation for future cycles. Results: 100% (25/25) of students somewhat or strongly agreed that their knowledge regarding laws and best practices increased and that their learning experience was enhanced by a mixed-methods approach. A total of 96% (24/25) of students stated that the mixed-methods instructional approach should be continued in the future. The SWOC analysis identified the mixed methods approach and student feedback as strengths and opportunities, while resource shortages and lack of impact assessment were identified as weaknesses and challenges. Conclusion: Creative redesign of instructional methods pertaining to law and best practices was effective to achieve positive student perceptions regarding instructional methods and learning. Future cycles should include rigorous assessment methods to evaluate impact on student learning and practice.

Analysis of Counterfeit Coated Tablets and Multi-Layer Packaging Materials Using Infrared Microspectroscopic Imaging.

PubMed

Winner, Taryn L; Lanzarotta, Adam; Sommer, André J

2016-06-01

An effective method for detecting and characterizing counterfeit finished dosage forms and packaging materials is described in this study. Using attenuated total internal reflection Fourier transform infrared spectroscopic imaging, suspect tablet coating and core formulations as well as multi-layered foil safety seals, bottle labels, and cigarette tear tapes were analyzed and compared directly with those of a stored authentic product. The approach was effective for obtaining molecular information from structures as small as 6 μm.

Laboratory measurements of radiance and reflectance spectra of a dilute biosolid industrial waste product

NASA Technical Reports Server (NTRS)

Usry, J. W.; Witte, W. G.; Whitlock, C. H.; Gurganus, E. A.

1979-01-01

Experimental measurements were made of upwelled spectral signatures of various concentrations of industrial waste products mixed with water in a large water tank. Radiance and reflectance spectra for a biosolid waste product (sludge) mixed with conditioned tap water and natural river water are reported. Results of these experiments indicate that reflectance increases with increasing concentration of the sludge at practically all wavelengths for concentration of total suspended solids up to 117 ppm in conditioned tap water and 171 ppm in natural river water. Significant variations in the spectra were observed and may be useful in defining spectral characteristics for this waste product. No significant spectral differences were apparent in the reflectance spectra of the two experiments, especially for wavelengths greater than 540 nm. Reflectance values, however, were generally greater in natural river water for wavelengths greater than 540 nm. Reflectance may be considered to increase linearly with concentration of total suspended solids from 5 to 171 ppm at all wavelengths without introducing errors larger than 10 percent.

Improving reflectance reconstruction from tristimulus values by adaptively combining colorimetric and reflectance similarities

NASA Astrophysics Data System (ADS)

Cao, Bin; Liao, Ningfang; Li, Yasheng; Cheng, Haobo

2017-05-01

The use of spectral reflectance as fundamental color information finds application in diverse fields related to imaging. Many approaches use training sets to train the algorithm used for color classification. In this context, we note that the modification of training sets obviously impacts the accuracy of reflectance reconstruction based on classical reflectance reconstruction methods. Different modifying criteria are not always consistent with each other, since they have different emphases; spectral reflectance similarity focuses on the deviation of reconstructed reflectance, whereas colorimetric similarity emphasizes human perception. We present a method to improve the accuracy of the reconstructed spectral reflectance by adaptively combining colorimetric and spectral reflectance similarities. The different exponential factors of the weighting coefficients were investigated. The spectral reflectance reconstructed by the proposed method exhibits considerable improvements in terms of the root-mean-square error and goodness-of-fit coefficient of the spectral reflectance errors as well as color differences under different illuminants. Our method is applicable to diverse areas such as textiles, printing, art, and other industries.

Ocean color remote sensing using polarization properties of reflected sunlight

NASA Technical Reports Server (NTRS)

Frouin, R.; Pouliquen, E.; Breon, F.-M.

1994-01-01

The effects of the atmosphere and surface on sunlight backscattered to space by the ocean may be substantially reduced by using the unpolarized component of reflectance instead of total reflectance. At 450 nm, a wavelength of interest in ocean color remote sensing, and for typical conditions, 45% of the unpolarized reflectance may originate from the water body instead of 20% of the total reflectance, which represents a gain of a factor 2.2 in useful signal for water composition retrieval. The best viewing geometries are adjacent to the glitter region; they correspond to scattering angles around 100 deg, but they may change slightly depending on the polarization characteristics of the aerosols. As aerosol optical thickness increases, the atmosphere becomes less efficient at polarizing sunlight, and the enhancement of the water body contribution to unpolarized reflectance is reduced. Since the perturbing effects are smaller on unpolarized reflectance, at least for some viewing geometries, they may be more easily corrected, leading to a more accurate water-leaving signal and, therefore, more accurate estimates of phytoplankton pigment concentration.

Reflection imaging of China ink-perfused brain vasculature using confocal laser-scanning microscopy after clarification of brain tissue by the Spalteholz method.

PubMed

Gutierre, R C; Vannucci Campos, D; Mortara, R A; Coppi, A A; Arida, R M

2017-04-01

Confocal laser-scanning microscopy is a useful tool for visualizing neurons and glia in transparent preparations of brain tissue from laboratory animals. Currently, imaging capillaries and venules in transparent brain tissues requires the use of fluorescent proteins. Here, we show that vessels can be imaged by confocal laser-scanning microscopy in transparent cortical, hippocampal and cerebellar preparations after clarification of China ink-injected specimens by the Spalteholz method. This method may be suitable for global, three-dimensional, quantitative analyses of vessels, including stereological estimations of total volume and length and of surface area of vessels, which constitute indirect approaches to investigate angiogenesis. © 2017 Anatomical Society.

Fuji apple storage time rapid determination method using Vis/NIR spectroscopy.

PubMed

Liu, Fuqi; Tang, Xuxiang

2015-01-01

Fuji apple storage time rapid determination method using visible/near-infrared (Vis/NIR) spectroscopy was studied in this paper. Vis/NIR diffuse reflection spectroscopy responses to samples were measured for 6 days. Spectroscopy data were processed by stochastic resonance (SR). Principal component analysis (PCA) was utilized to analyze original spectroscopy data and SNR eigen value. Results demonstrated that PCA could not totally discriminate Fuji apples using original spectroscopy data. Signal-to-noise ratio (SNR) spectrum clearly classified all apple samples. PCA using SNR spectrum successfully discriminated apple samples. Therefore, Vis/NIR spectroscopy was effective for Fuji apple storage time rapid discrimination. The proposed method is also promising in condition safety control and management for food and environmental laboratories.

Development of Noninvasive Blood Glucose Sensor Using the Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Fujita, Keiichi; Tamura, Kazuto; Kaneko, Wataru; Ishizawa, Hiroaki; Toba, Eiji

Recently, diabetics have been steadily increasing, because change of diet, lack of exercise, increase an alcoholic intake, and increase a stress. It is a very serious problem for us. About 23.6 millions of people in Japan approach the danger of diabetes. Therefore, it is necessary to get insulin injection. And they have to measure blood glucose again and again a day. So, they are burden too heavy. This paper describes a new noninvasive measurement of blood glucose based on optical sensing. This uses Fourier transform infrared spectroscopy of attenuated total reflection. Non-invasive measurement was carried out by using 3 methods. And standard error of prediction is about ±20mg/dl by 3 method. This paper also describes practical application of this method.

Efficient tiled calculation of over-10-gigapixel holograms using ray-wavefront conversion.

PubMed

Igarashi, Shunsuke; Nakamura, Tomoya; Matsushima, Kyoji; Yamaguchi, Masahiro

2018-04-16

In the calculation of large-scale computer-generated holograms, an approach called "tiling," which divides the hologram plane into small rectangles, is often employed due to limitations on computational memory. However, the total amount of computational complexity severely increases with the number of divisions. In this paper, we propose an efficient method for calculating tiled large-scale holograms using ray-wavefront conversion. In experiments, the effectiveness of the proposed method was verified by comparing its calculation cost with that using the previous method. Additionally, a hologram of 128K × 128K pixels was calculated and fabricated by a laser-lithography system, and a high-quality 105 mm × 105 mm 3D image including complicated reflection and translucency was optically reconstructed.

Fuji apple storage time rapid determination method using Vis/NIR spectroscopy

PubMed Central

Liu, Fuqi; Tang, Xuxiang

2015-01-01

Fuji apple storage time rapid determination method using visible/near-infrared (Vis/NIR) spectroscopy was studied in this paper. Vis/NIR diffuse reflection spectroscopy responses to samples were measured for 6 days. Spectroscopy data were processed by stochastic resonance (SR). Principal component analysis (PCA) was utilized to analyze original spectroscopy data and SNR eigen value. Results demonstrated that PCA could not totally discriminate Fuji apples using original spectroscopy data. Signal-to-noise ratio (SNR) spectrum clearly classified all apple samples. PCA using SNR spectrum successfully discriminated apple samples. Therefore, Vis/NIR spectroscopy was effective for Fuji apple storage time rapid discrimination. The proposed method is also promising in condition safety control and management for food and environmental laboratories. PMID:25874818

Artificially controlled backscattering in single mode fibers based on femtosecond laser fabricated reflectors

NASA Astrophysics Data System (ADS)

Wang, Xiaoliang; Chen, Daru; Li, Haitao; Wu, Qiong

2018-04-01

A novel method to artificially control the backscattering of the single-mode fiber (SMF) is proposed and investigated for the first time. This method can help to fabricate a high backscattering fiber (HBSF), such as by fabricating reflectors in every one meter interval of an SMF based on the exposure of the femtosecond laser beam. The artificially controlled backscattering (ACBS) can be much higher than the natural Rayleigh backscattering (RB) of the SMF. The RB power and ACBS power in the unit length fiber are derived according to the theory of the RBS. The total relative power and the relative back power reflected in the unit length of the HBSF have been simulated and presented. The simulated results show that the HBSF has the characteristics of both low optical attenuation and high backscattering. The relative back power reflected in the unit length of the HBSF is 25dB larger than the RB power of the SMF when the refractive index modulation quantity of the reflectors is 0.009. Some preliminary experiments also indicate that the method fabricating reflectors to increase the backscattering power of the SMF is practical and promising.

The effect of surface anisotropy on the accuracy of total ozone estimates from satellite observations

NASA Technical Reports Server (NTRS)

Fraser, R. S.; Ahmad, Z.

1978-01-01

The total amount of ozone in a vertical column of the earth's atmosphere is being derived from satellite measurements of the intensity of ultraviolet sunlight scattered by the earth-atmosphere system. The algorithm for deriving the ozone amount utilizes the assumption that the earth's surface reflects the incident light isotropically according to Lambert's law. Natural surface reflection deviates more or less from this law. Two extreme examples of anisotropic reflection from dark ocean and from bright snow are analyzed by means of models for their effects on the derived values of ozone.

Analysis of Ti and TiO2 nanolayers by total reflection X-ray photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Kubala-Kukuś, A.; Banaś, D.; Stabrawa, I.; Szary, K.; Sobota, D.; Majewska, U.; Wudarczyk-Moćko, J.; Braziewicz, J.; Pajek, M.

2018-07-01

Total reflection X-ray photoelectron spectroscopy (TRXPS) is applied in the analysis of Ti and TiO2 nanolayers deposited on silicon and silicon dioxide substrates. The idea of application of total-reflection phenomenon for exciting X-ray used in the XPS technique is briefly discussed. The experimental setup and measurement conditions for the studied Ti and TiO2 layers are presented. The XPS spectra were registered both for the non-total and total reflection regimes. The survey spectra and C1s, N1s, Ti2p and O1s photoelectron peaks are shown. For energy calibration, the position of C1s photoelectron peak was applied (C-C component, binding energy 284.8 eV). The peak to background ratios are discussed as regards the dependence of the excitation angle. An increase of this ratio for the glancing angle 1°, being below critical angle of the X-ray beam and sample material, results in an improvement of XPS detection limit by factor up to 2. In the case of the Ti nanolayer, additionally, the thickness of the overlayer TiO2 is determined. As an example of applying the TRXPS technique, the analysis of Ti nanolayers implanted by highly charged Xe35+ ions of 280 keV energy is discussed. The Xe3d and O1s photoelectron peaks are presented and discussed.

Flavonoid and Antioxidant Capacity of Propolis Prediction Using Near Infrared Spectroscopy.

PubMed

Betances-Salcedo, Eddy; Revilla, Isabel; Vivar-Quintana, Ana M; González-Martín, M Inmaculada

2017-07-18

The use of propolis as a dietary supplement or as an ingredient in different food products is increasing, due to its antioxidant and bactericidal properties. These nutritional properties directly depend on its phenolic composition. For this reason, this study analysed the total contents of flavones and flavonols, flavanones and dihydroflavonols, and the antioxidant capacity by using the methods of ABTS and linoleic acid/ β -carotene in 99 samples of propolis from Spain and Chile. A rapid method was developed for quantifying these parameters in raw propolis using near infrared (NIR) spectroscopy with a remote reflectance fibre-optic probe applied directly to the ground-up sample. The models developed allow for the determination of the total flavones and flavonols (0-183 mg quercetin/g propolis and 0-72 mg rutin/g propolis), of the total flavanones and dihydroflavonols (9-109 mg pinocembrin/g propolis extract), and of its antioxidant capacity by the ABTS method based on the reduction of the 2.2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation(0-3212.6 nmol Trolox/mg of propolis) and of linoleic acid/ β -carotene (22-86% inhibition). The NIR spectroscopy models were applied in external validation to different samples of the calibration group, which led to the conclusion that the methods developed provide significantly identical data to the initial chemical data of reference.

Inflight Microbial Monitoring- An Alternative Method to Culture Based Detection Currently Used on the International Space Station

NASA Technical Reports Server (NTRS)

Khodadad, Christina L.; Birmele, Michele N.; Roman, Monsi; Hummerick, Mary E.; Smith, David J.; Wheeler, Raymond M.

2015-01-01

Previous research has shown that potentially destructive microorganisms and human pathogens have been detected on the International Space Station (ISS). The likelihood of introducing new microorganisms occurs with every exchange of crew or addition of equipment or supplies. Microorganisms introduced to the ISS are readily transferred between crew and subsystems (i.e. ECLSS, environmental control and life support systems). Current microbial characterization methods require enrichment of microorganisms and at least a 48-hour incubation time. This increases the microbial load while detecting only a limited number of the total microorganisms. The culture based method detects approximately 1-10% of the total organisms present and provides no identification. To identify and enumerate ISS microbes requires that samples be returned to Earth for complete analysis. Therefore, a more expedient, low-cost, in-flight method of microbial detection, identification, and enumeration is warranted. The RAZOR EX, a ruggedized, commercial off the shelf, real-time PCR field instrument was tested for its ability to detect microorganisms at low concentrations within one hour. Escherichia coli, Salmonella enterica Typhimurium, and Pseudomonas aeruginosa were detected at low levels using real-time DNA amplification. Total heterotrophic counts could also be detected using a 16S gene marker that can identify up to 98% of all bacteria. To reflect viable cells found in the samples, RNA was also detectable using a modified, single-step reverse transcription reaction.

Diffractive flat panel solar concentrators of a novel design.

PubMed

de Jong, Ties M; de Boer, Dick K G; Bastiaansen, Cees W M

2016-07-11

A novel design for a flat panel solar concentrator is presented which is based on a light guide with a grating applied on top that diffracts light into total internal reflection. By combining geometrical and diffractive optics the geometrical concentration ratio is optimized according to the principles of nonimaging optics, while the thickness of the device is minimized due to the use of total internal reflection.

Advances in spectroscopic methods for quantifying soil carbon

USGS Publications Warehouse

Liebig, Mark; Franzluebbers, Alan J.; Follett, Ronald F.; Hively, W. Dean; Reeves, James B.; McCarty, Gregory W.; Calderon, Francisco

2012-01-01

The gold standard for soil C determination is combustion. However, this method requires expensive consumables, is limited to the determination of the total carbon and in the number of samples which can be processed (~100/d). With increased interest in soil C sequestration, faster methods are needed. Thus, interest in methods based on diffuse reflectance spectroscopy in the visible, near-infrared or mid-infrared ranges using either proximal or remote sensing. These methods have the ability to analyze more samples (2 to 3X/d) or huge areas (imagery) and do multiple analytes simultaneously, but require calibrations relating spectral and reference data and have specific problems, i.e., remote sensing is capable of scanning entire watersheds, thus reducing the sampling needed, but is limiting to the surface layer of tilled soils and by difficulty in obtaining proper calibration reference values. The objective of this discussion is the present state of spectroscopic methods for soil C determination.

Design Rules for Tailoring Antireflection Properties of Hierarchical Optical Structures

DOE PAGES

Leon, Juan J. Diaz; Hiszpanski, Anna M.; Bond, Tiziana C.; ...

2017-05-18

Hierarchical structures consisting of small sub-wavelength features stacked atop larger structures have been demonstrated as an effective means of reducing the reflectance of surfaces. However, optical devices require different antireflective properties depending on the application, and general unifying guidelines on hierarchical structures' design to attain a desired antireflection spectral response are still lacking. The type of reflectivity (diffuse, specular, or total/hemispherical) and its angular- and spectral-dependence are all dictated by the structural parameters. Through computational and experimental studies, guidelines have been devised to modify these various aspects of reflectivity across the solar spectrum by proper selection of the features ofmore » hierarchical structures. In this wavelength regime, micrometer-scale substructures dictate the long-wavelength spectral response and effectively reduce specular reflectance, whereas nanometer-scale substructures dictate primarily the visible wavelength spectral response and reduce diffuse reflectance. Coupling structures having these two length scales into hierarchical arrays impressively reduces surfaces' hemispherical reflectance across a broad spectrum of wavelengths and angles. Furthermore, such hierarchical structures in silicon are demonstrated having an average total reflectance across the solar spectrum of 1.1% (average weighted reflectance of 1% in the 280–2500 nm range of the AM 1.5 G spectrum) and specular reflectance <1% even at angles of incidence as high as 67°.« less

Arterial Wave Reflection and Aortic Valve Calcification in an Elderly Community-Based Cohort

PubMed Central

Sera, Fusako; Russo, Cesare; Iwata, Shinichi; Jin, Zhezhen; Rundek, Tatjana; Elkind, Mitchell S.V.; Homma, Shunichi; Sacco, Ralph L.; Di Tullio, Marco R.

2015-01-01

Background Aortic valve calcification (AVC) without stenosis is common in the elderly, is associated with cardiovascular morbidity and mortality, and may progress to aortic valve stenosis. Arterial stiffness and pulse wave reflection are important components of proximal aortic hemodynamics, but their relationship with AVC is not established. Methods To investigate the relationship of arterial wave reflection and stiffness with AVC, pulse wave analysis and AVC evaluation by echocardiography were performed in 867 participants from the Cardiovascular Abnormalities and Brain Lesions (CABL) study. Participants were divided into 4 categories based on the severity and extent of AVC: 1) none or mild focal AVC; 2) mild diffuse AVC; 3) moderate-severe focal AVC; and 4) moderate-severe diffuse AVC. Central blood pressures and pulse pressure, total arterial compliance, augmentation index, and time to wave reflection were assessed using applanation tonometry. Results Indicators of arterial stiffness and wave reflection were significantly associated with AVC severity, except for central systolic and diastolic pressures and time to reflection. After adjustment for pertinent covariates (age, sex, race/ethnicity, and eGFR), only augmentation pressure (P = .02) and augmentation index (P = .002) were associated with the severity of AVC. Multivariable logistic regression analysis revealed that augmentation pressure (odds ratio per mmHg = 1.14; 95% confidence interval, 1.02–1.27; P = .02) and augmentation index (odds ratio per percentage point = 1.07; 95% confidence interval, 1.01–1.13; P = .02) were associated with an increase risk of moderate-severe diffuse AVC, even when central blood pressure value was included in the same model. Conclusions Arterial wave reflection is associated with AVC severity, independent of blood pressure values. Increased contribution of wave reflection to central blood pressure could be involved in the process leading to AVC. PMID:25600036

Determinants of nursing competence of nursing students in Taiwan: the role of self-reflection and insight.

PubMed

Eng, Cheng-Joo; Pai, Hsiang-Chu

2015-03-01

A nursing practicum course is critical to strengthening the nursing competence of nursing students. Research has found that practice stress and coping behaviors can have either a negative or positive influence on the learning and practice performance of nursing students. Nevertheless, there are few evidence-based studies related to the relationship between self-reflection and insight and nursing competence in Taiwanese nursing students. To test the determinants and the effect of self-reflection and insight on nursing competence in nursing students during the first 2 months of their practice experience. Cross-sectional and correlational research designs were employed. From September to November 2013, a total of 312 nursing students at a junior college in southern Taiwan served as participants in this study. Four questionnaires were used to collect data: Self-reflection and Insight Scale (SRIS), Perceived Stress Scale (PSS), Coping Behavior Inventory (CBI), and Holistic Nursing Competence Scale (HNCS). The research model was evaluated through structural equation modeling (SEM), with the use of the partial least squares (PLS) method. Results indicated that self-reflection and insight, practice stress, and practice coping behavior were statistically significantly associated with nursing competence. In addition, self-reflection and insight were significantly and positively associated with practice coping behavior and negatively associated with practice stress. Students' coping behavior partially mediates the effect of self-reflection and stress on nursing competence. Overall, these variables explained 39.4% of the variance in these students' nursing competence. Self-reflection and insight affected nursing competence during the practice period. These variables have not only had a direct influence on nursing competence but also an indirect effect through the mediating effect of coping behavior and stress. Copyright © 2014 Elsevier Ltd. All rights reserved.

Modeling the effect of reflection from metallic walls on spectroscopic measurements.

PubMed

Zastrow, K-D; Keatings, S R; Marot, L; O'Mullane, M G; de Temmerman, G

2008-10-01

A modification of JET is presently being prepared to bring operational experience with ITER-like first wall (Be) and divertor (W) materials, geometry and plasma parameters. Reflectivity measurements of JET sample tiles have been performed and the data are used within a simplified model of the JET and ITER vessels to predict additional contributions to quantitative spectroscopic measurements. The most general method to characterize reflectivity is the bidirectional reflection distribution function (BRDF). For extended sources however, such as bremsstrahlung and edge emission of fuel and intrinsic impurities, the results obtained in the modeling are almost as accurate if the total reflectivity with ideal Lambertian angular dependence is used. This is in contrast to the experience in other communities, such as optical design, lighting design, or rendering who deal mostly with pointlike light sources. This result is so far based on a very limited set of measurements and will be reassessed when more detailed BRDF measurements of JET tiles have been made. If it is true it offers the possibility of in situ monitoring of the reflectivity of selected parts of the wall during exposure to plasma operation, while remeasurement of the BRDF is performed during interventions. For a closed vessel structure such as ITER, it is important to consider multiple reflections. This makes it more important to represent the whole of the vessel reasonably accurately in the model, which on the other hand is easier to achieve than for the more complex internal structure of JET. In both cases the dominant contribution is from the first reflection, and a detailed model of the areas intersected by lines of sight of diagnostic interest is required.

A dilute-and-shoot sample preparation strategy for new and used lubricating oils for Ca, P, S and Zn determination by total reflection X-ray fluorescence

NASA Astrophysics Data System (ADS)

Mota, Mariana F. B.; Gama, Ednilton M.; Rodrigues, Gabrielle de C.; Rodrigues, Guilherme D.; Nascentes, Clésia C.; Costa, Letícia M.

2018-01-01

In this work, a dilute-and-shoot method was developed for Ca, P, S and Zn determination in new and used lubricating oil samples by total reflection X-ray fluorescence (TXRF). The oil samples were diluted with organic solvents followed by addition of yttrium as internal standard and the TXRF measurements were performed after solvent evaporation. The method was optimized using an interlaboratorial reference material. The experimental parameters evaluated were sample volume (50 or 100 μL), measurement time (250 or 500 s) and volume deposited on the quartz glass sample carrier (5 or 10 μL). All of them were evaluated and optimized using xylene, kerosene and hexane. Analytical figures of merit (accuracy, precision, limit of detection and quantification) were used to evaluate the performance of the analytical method for all solvents. The recovery rates varied from 99 to 111% and the relative standard deviation remained between 1.7% and 10% (n = 8). For all elements, the results obtained by applying the new method were in agreement with the certified value. After the validation step, the method was applied for Ca, P, S and Zn quantification in eight new and four used lubricating oil samples, for all solvents. The concentration of the elements in the samples varied in the ranges of 1620-3711 mg L- 1 for Ca, 704-1277 mg L- 1 for P, 2027-9147 mg L- 1 for S, and 898-1593 mg L- 1 for Zn. The association of TXRF with a dilute-and-shoot sample preparation strategy was efficient for Ca, P, S and Zn determination in lubricating oils, presenting accurate results. Additionally, the time required for analysis is short, the reagent volumes are low minimizing waste generation, and the technique does not require calibration curves.

Method and tool to reverse the charges in anti-reflection films used for solar cell applications

DOEpatents

Sharma, Vivek; Tracy, Clarence

2017-01-31

A method is provided for making a solar cell. The method includes providing a stack including a substrate, a barrier layer disposed on the substrate, and an anti-reflective layer disposed on the barrier layer, where the anti-reflective layer has charge centers. The method also includes generating a corona with a charging tool and contacting the anti-reflective layer with the corona thereby injecting charge into at least some of the charge centers in the anti-reflective layer. Ultra-violet illumination and temperature-based annealing may be used to modify the charge of the anti-reflective layer.

Total sulfur determination in residues of crude oil distillation using FT-IR/ATR and variable selection methods.

PubMed

Müller, Aline Lima Hermes; Picoloto, Rochele Sogari; de Azevedo Mello, Paola; Ferrão, Marco Flores; de Fátima Pereira dos Santos, Maria; Guimarães, Regina Célia Lourenço; Müller, Edson Irineu; Flores, Erico Marlon Moraes

2012-04-01

Total sulfur concentration was determined in atmospheric residue (AR) and vacuum residue (VR) samples obtained from petroleum distillation process by Fourier transform infrared spectroscopy with attenuated total reflectance (FT-IR/ATR) in association with chemometric methods. Calibration and prediction set consisted of 40 and 20 samples, respectively. Calibration models were developed using two variable selection models: interval partial least squares (iPLS) and synergy interval partial least squares (siPLS). Different treatments and pre-processing steps were also evaluated for the development of models. The pre-treatment based on multiplicative scatter correction (MSC) and the mean centered data were selected for models construction. The use of siPLS as variable selection method provided a model with root mean square error of prediction (RMSEP) values significantly better than those obtained by PLS model using all variables. The best model was obtained using siPLS algorithm with spectra divided in 20 intervals and combinations of 3 intervals (911-824, 823-736 and 737-650 cm(-1)). This model produced a RMSECV of 400 mg kg(-1) S and RMSEP of 420 mg kg(-1) S, showing a correlation coefficient of 0.990. Copyright © 2011 Elsevier B.V. All rights reserved.

Performance of three reflectance calibration methods for airborne hyperspectral spectrometer data.

PubMed

Miura, Tomoaki; Huete, Alfredo R

2009-01-01

In this study, the performances and accuracies of three methods for converting airborne hyperspectral spectrometer data to reflectance factors were characterized and compared. The "reflectance mode (RM)" method, which calibrates a spectrometer against a white reference panel prior to mounting on an aircraft, resulted in spectral reflectance retrievals that were biased and distorted. The magnitudes of these bias errors and distortions varied significantly, depending on time of day and length of the flight campaign. The "linear-interpolation (LI)" method, which converts airborne spectrometer data by taking a ratio of linearly-interpolated reference values from the preflight and post-flight reference panel readings, resulted in precise, but inaccurate reflectance retrievals. These reflectance spectra were not distorted, but were subject to bias errors of varying magnitudes dependent on the flight duration length. The "continuous panel (CP)" method uses a multi-band radiometer to obtain continuous measurements over a reference panel throughout the flight campaign, in order to adjust the magnitudes of the linear-interpolated reference values from the preflight and post-flight reference panel readings. Airborne hyperspectral reflectance retrievals obtained using this method were found to be the most accurate and reliable reflectance calibration method. The performances of the CP method in retrieving accurate reflectance factors were consistent throughout time of day and for various flight durations. Based on the dataset analyzed in this study, the uncertainty of the CP method has been estimated to be 0.0025 ± 0.0005 reflectance units for the wavelength regions not affected by atmospheric absorptions. The RM method can produce reasonable results only for a very short-term flight (e.g., < 15 minutes) conducted around a local solar noon. The flight duration should be kept shorter than 30 minutes for the LI method to produce results with reasonable accuracies. An important advantage of the CP method is that the method can be used for long-duration flight campaigns (e.g., 1-2 hours). Although this study focused on reflectance calibration of airborne spectrometer data, the methods evaluated in this study and the results obtained are directly applicable to ground spectrometer measurements.

Total protein of whole saliva as a biomarker of anaerobic threshold.

PubMed

Bortolini, Miguel Junior Sordi; De Agostini, Guilherme Gularte; Reis, Ismair Teodoro; Lamounier, Romeu Paulo Martins Silva; Blumberg, Jeffrey B; Espindola, Foued Salmen

2009-09-01

Saliva provides a convenient and noninvasive matrix for assessing specific physiological parameters, including some biomarkers of exercise. We investigated whether the total protein concentration of whole saliva (TPWS) would reflect the anaerobic threshold during an incremental exercise test. After a warm-up period, 13 nonsmoking men performed a maximum incremental exercise on a cycle ergometer. Blood and stimulated saliva were collected during the test. The TPWS anaerobic threshold (PAT) was determined using the Dmax method. The PAT was correlated with the blood lactate anaerobic threshold (AT; r = .93, p < .05). No significant difference (p = .16) was observed between PAT and AT. Thus, TPWS provides a convenient and noninvasive matrix for determining the anaerobic threshold during incremental exercise tests.

Rapid and Simultaneous Prediction of Eight Diesel Quality Parameters through ATR-FTIR Analysis.

PubMed

Nespeca, Maurilio Gustavo; Hatanaka, Rafael Rodrigues; Flumignan, Danilo Luiz; de Oliveira, José Eduardo

2018-01-01

Quality assessment of diesel fuel is highly necessary for society, but the costs and time spent are very high while using standard methods. Therefore, this study aimed to develop an analytical method capable of simultaneously determining eight diesel quality parameters (density; flash point; total sulfur content; distillation temperatures at 10% (T10), 50% (T50), and 85% (T85) recovery; cetane index; and biodiesel content) through attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and the multivariate regression method, partial least square (PLS). For this purpose, the quality parameters of 409 samples were determined using standard methods, and their spectra were acquired in ranges of 4000-650 cm -1 . The use of the multivariate filters, generalized least squares weighting (GLSW) and orthogonal signal correction (OSC), was evaluated to improve the signal-to-noise ratio of the models. Likewise, four variable selection approaches were tested: manual exclusion, forward interval PLS (FiPLS), backward interval PLS (BiPLS), and genetic algorithm (GA). The multivariate filters and variables selection algorithms generated more fitted and accurate PLS models. According to the validation, the FTIR/PLS models presented accuracy comparable to the reference methods and, therefore, the proposed method can be applied in the diesel routine monitoring to significantly reduce costs and analysis time.

Rapid and Simultaneous Prediction of Eight Diesel Quality Parameters through ATR-FTIR Analysis

PubMed Central

Hatanaka, Rafael Rodrigues; Flumignan, Danilo Luiz; de Oliveira, José Eduardo

2018-01-01

Quality assessment of diesel fuel is highly necessary for society, but the costs and time spent are very high while using standard methods. Therefore, this study aimed to develop an analytical method capable of simultaneously determining eight diesel quality parameters (density; flash point; total sulfur content; distillation temperatures at 10% (T10), 50% (T50), and 85% (T85) recovery; cetane index; and biodiesel content) through attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and the multivariate regression method, partial least square (PLS). For this purpose, the quality parameters of 409 samples were determined using standard methods, and their spectra were acquired in ranges of 4000–650 cm−1. The use of the multivariate filters, generalized least squares weighting (GLSW) and orthogonal signal correction (OSC), was evaluated to improve the signal-to-noise ratio of the models. Likewise, four variable selection approaches were tested: manual exclusion, forward interval PLS (FiPLS), backward interval PLS (BiPLS), and genetic algorithm (GA). The multivariate filters and variables selection algorithms generated more fitted and accurate PLS models. According to the validation, the FTIR/PLS models presented accuracy comparable to the reference methods and, therefore, the proposed method can be applied in the diesel routine monitoring to significantly reduce costs and analysis time. PMID:29629209

Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride) Membranes

PubMed Central

Liu, Jie; Lu, Xiaolong; Wu, Chunrui

2013-01-01

Poly(vinylidene fluoride) (PVDF) membranes were prepared by non solvent induced phase separation (NIPS), melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and X-ray diffraction (XRD) were employed to examine the crystal form of the surface layers and the overall membranes, respectively. Spherulite morphologies and thermal behavior of the membranes were studied by polarized light optical microscopy (PLO) and differential scanning calorimetry (DSC) separately. It was found that the crystallization behavior of PVDF membranes was closely related to the preparation methods. For membranes prepared by the NIPS method, the skin layers had a mixture of α and β phases, the overall membranes were predominantly α phase, and the total crystallinity was 60.0% with no spherulite. For melt spinning membranes, the surface layers also showed a mixture of α and β phases, the overall membranes were predominantly α phase. The total crystallinity was 48.7% with perfect spherulites. Whereas the crystallization behavior of solution-cast membranes was related to the evaporation temperature and the additive, when the evaporation temperature was 140 °C with a soluble additive in the dope solution, obvious spherulites appeared. The crystalline morphology of PVDF exerted a great influence on the tensile strength of the membranes, which was much higher with perfect spherulites. PMID:24957064

Comparison of Attenuated Total Reflectance Mid-Infrared, Near Infrared, and 1H-Nuclear Magnetic Resonance Spectroscopies for the Determination of Coffee's Geographical Origin

PubMed Central

Caro Rodríguez, Diana; Arana, Victoria A.; Bernal, Andrés; Esseiva, Pierre

2017-01-01

The sensorial properties of Colombian coffee are renowned worldwide, which is reflected in its market value. This raises the threat of fraud by adulteration using coffee grains from other countries, thus creating a demand for robust and cost-effective methods for the determination of geographical origin of coffee samples. Spectroscopic techniques such as Nuclear Magnetic Resonance (NMR), near infrared (NIR), and mid-infrared (mIR) have arisen as strong candidates for the task. Although a body of work exists that reports on their individual performances, a faithful comparison has not been established yet. We evaluated the performance of 1H-NMR, Attenuated Total Reflectance mIR (ATR-mIR), and NIR applied to fraud detection in Colombian coffee. For each technique, we built classification models for discrimination by species (C. arabica versus C. canephora (or robusta)) and by origin (Colombia versus other C. arabica) using a common set of coffee samples. All techniques successfully discriminated samples by species, as expected. Regarding origin determination, ATR-mIR and 1H-NMR showed comparable capacity to discriminate Colombian coffee samples, while NIR fell short by comparison. In conclusion, ATR-mIR, a less common technique in the field of coffee adulteration and fraud detection, emerges as a strong candidate, faster and with lower cost compared to 1H-NMR and more discriminating compared to NIR. PMID:29201055

Reflective and refractive objects for mixed reality.

PubMed

Knecht, Martin; Traxler, Christoph; Winklhofer, Christoph; Wimmer, Michael

2013-04-01

In this paper, we present a novel rendering method which integrates reflective or refractive objects into a differential instant radiosity (DIR) framework usable for mixed-reality (MR) applications. This kind of objects are very special from the light interaction point of view, as they reflect and refract incident rays. Therefore they may cause high-frequency lighting effects known as caustics. Using instant-radiosity (IR) methods to approximate these high-frequency lighting effects would require a large amount of virtual point lights (VPLs) and is therefore not desirable due to real-time constraints. Instead, our approach combines differential instant radiosity with three other methods. One method handles more accurate reflections compared to simple cubemaps by using impostors. Another method is able to calculate two refractions in real-time, and the third method uses small quads to create caustic effects. Our proposed method replaces parts in light paths that belong to reflective or refractive objects using these three methods and thus tightly integrates into DIR. In contrast to previous methods which introduce reflective or refractive objects into MR scenarios, our method produces caustics that also emit additional indirect light. The method runs at real-time frame rates, and the results show that reflective and refractive objects with caustics improve the overall impression for MR scenarios.

Sequential fitting-and-separating reflectance components for analytical bidirectional reflectance distribution function estimation.

PubMed

Lee, Yu; Yu, Chanki; Lee, Sang Wook

2018-01-10

We present a sequential fitting-and-separating algorithm for surface reflectance components that separates individual dominant reflectance components and simultaneously estimates the corresponding bidirectional reflectance distribution function (BRDF) parameters from the separated reflectance values. We tackle the estimation of a Lafortune BRDF model, which combines a nonLambertian diffuse reflection and multiple specular reflectance components with a different specular lobe. Our proposed method infers the appropriate number of BRDF lobes and their parameters by separating and estimating each of the reflectance components using an interval analysis-based branch-and-bound method in conjunction with iterative K-ordered scale estimation. The focus of this paper is the estimation of the Lafortune BRDF model. Nevertheless, our proposed method can be applied to other analytical BRDF models such as the Cook-Torrance and Ward models. Experiments were carried out to validate the proposed method using isotropic materials from the Mitsubishi Electric Research Laboratories-Massachusetts Institute of Technology (MERL-MIT) BRDF database, and the results show that our method is superior to a conventional minimization algorithm.

Algorithm for retrieving vegetative canopy and leaf parameters from multi- and hyperspectral imagery

NASA Astrophysics Data System (ADS)

Borel, Christoph

2009-05-01

In recent years hyper-spectral data has been used to retrieve information about vegetative canopies such as leaf area index and canopy water content. For the environmental scientist these two parameters are valuable, but there is potentially more information to be gained as high spatial resolution data becomes available. We developed an Amoeba (Nelder-Mead or Simplex) based program to invert a vegetative canopy radiosity model coupled with a leaf (PROSPECT5) reflectance model and modeled for the background reflectance (e.g. soil, water, leaf litter) to a measured reflectance spectrum. The PROSPECT5 leaf model has five parameters: leaf structure parameter Nstru, chlorophyll a+b concentration Cab, carotenoids content Car, equivalent water thickness Cw and dry matter content Cm. The canopy model has two parameters: total leaf area index (LAI) and number of layers. The background reflectance model is either a single reflectance spectrum from a spectral library() derived from a bare area pixel on an image or a linear mixture of soil spectra. We summarize the radiosity model of a layered canopy and give references to the leaf/needle models. The method is then tested on simulated and measured data. We investigate the uniqueness, limitations and accuracy of the retrieved parameters on canopy parameters (low, medium and high leaf area index) spectral resolution (32 to 211 band hyperspectral), sensor noise and initial conditions.

Reflective properties of randomly rough surfaces under large incidence angles.

PubMed

Qiu, J; Zhang, W J; Liu, L H; Hsu, P-f; Liu, L J

2014-06-01

The reflective properties of randomly rough surfaces at large incidence angles have been reported due to their potential applications in some of the radiative heat transfer research areas. The main purpose of this work is to investigate the formation mechanism of the specular reflection peak of rough surfaces at large incidence angles. The bidirectional reflectance distribution function (BRDF) of rough aluminum surfaces with different roughnesses at different incident angles is measured by a three-axis automated scatterometer. This study used a validated and accurate computational model, the rigorous coupled-wave analysis (RCWA) method, to compare and analyze the measurement BRDF results. It is found that the RCWA results show the same trend of specular peak as the measurement. This paper mainly focuses on the relative roughness at the range of 0.16<σ/λ<5.35. As the relative roughness decreases, the specular peak enhancement dramatically increases and the scattering region significantly reduces, especially under large incidence angles. The RCWA and the Rayleigh criterion results have been compared, showing that the relative error of the total integrated scatter increases as the roughness of the surface increases at large incidence angles. In addition, the zero-order diffractive power calculated by RCWA and the reflectance calculated by Fresnel equations are compared. The comparison shows that the relative error declines sharply when the incident angle is large and the roughness is small.

Non-destructive evaluation of specialty coating degradation using terahertz time-domain spectroscopy

NASA Astrophysics Data System (ADS)

Nicoletti, Carley R.; Cramer, Laura; Fletcher, Alan; Zimdars, David; Iqbal, Zafar; Federici, John F.

2017-05-01

The Terahertz Time Domain Reflection Spectroscopy (THz-TDS) method of paint layer diagnostics is a non-contact electromagnetic technique analogous to pulsed-ultrasound with the added capability of spectroscopic characterization. The THz-TDS sensor emits a near-single cycle electromagnetic pulse with a bandwidth from 0.1 to 3 THz. This wide bandwidth pulse is focused on the coating, and echo pulses are generated from each interface (air-coating, layer-layer, coating-substrate). In this paper, the THz-TDS method is applied to specialty aircraft coatings. The THz-TDS method is able to penetrate the whole coating stack and sample the properties of each layer. Because the reflected pulses from individual layers typically overlap in time, the complex permittivity function and thickness of each layer is determined by a best fit of the measured reflection (either in time or frequency domain) to a layered model of the paint. The THz- TDS method is applied to specialty coatings prior to and during accelerated aging on a series of test coupons. The coupons are also examined during aging using ATR (attenuated total reflectance)-FTIR spectroscopy, Raman scattering spectroscopy, and Scanning Electron Microscopy (SEM) to ascertain, quantify, and understand the breakdown mechanisms of the coatings. In addition, the same samples are characterized using THz-TDS techniques to determine if the THz-TDS method can be utilized as a non-destructive evaluation technique to sense degradation of the coatings. Our results suggest that the degradation mechanism begins in the top coat layer. In this layer, 254 nm UV illumination in combination with the presence of moisture works partially with oxides as catalysts to decompose the polymer matrix thereby creating porosity in the top coat layer. Since the catalytic effect is partial, loss of the oxides by chemical reaction can also occur. As the topcoat layer becomes more porous, it allows water vapor to permeate the topcoat layer and interact with the rain erosion layer via carbonization of the polymer matrix in the rain erosion layer. The presence of the salt accelerates the pitting degradation. The goal of this paper is to determine if THz-TDS can be used to sense degradation of the coating.

Correlation Between Skin Color Evaluation by Skin Color Scale Chart and Narrowband Reflectance Spectrophotometer

PubMed Central

Treesirichod, Arucha; Chansakulporn, Somboon; Wattanapan, Pattra

2014-01-01

Context: Various methods are available for the evaluation of skin color. A skin color scale chart is a convenient and inexpensive tool. However, the correlation between a skin color scale chart and objective measurement has not been evaluated. Aims: To assess the correlation between skin color evaluation done by a skin color scale chart (Felix von Luschan skin color chart) and a narrowband reflectance spectrophotometer (Mexameter MX18). Materials and Methods: The participants were evaluated for skin color by using the Felix von Luschan skin color chart (range 1-36) and a narrowband reflectance spectrophotometer (Mexameter MX18) in which the results of the measurements were expressed as Erythema (E) and Melanin (M) indices. Skin color was measured on four different anatomical skin sites from each participant on the medial aspect of the volar and the dorsal regions of both forearms. Results: A total of 208 records from 52 participants were established. The majority of participants (19.2%) were rated with the skin color scale at the number 16 (range 14-33). The mean M plus E, M, and E indices were 498.9 ± 143.9, 230.4 ± 74.4, and 268.5 ± 73.2, respectively. The correlation coefficient between the number on the skin color scale and each index: M plus E, M, and E indices were 0.90, 0.90, and 0.86, respectively, with a statistical significance of P < 0.001. Conclusions: Skin color evaluation using a skin color scale chart has shown a high correlation with skin color evaluation done by the narrowband reflectance spectrophotometer. PMID:25071249

Blended learning for reinforcing dental pharmacology in the clinical years: A qualitative analysis

PubMed Central

Eachempati, Prashanti; Kiran Kumar, K. S.; Sumanth, K. N.

2016-01-01

Objectives: Blended learning has become the method of choice in educational institutions because of its systematic integration of traditional classroom teaching and online components. This study aims to analyze student’s reflection regarding blended learning in dental pharmacology. Subjects and Methods: A cross-sectional study was conducted in Faculty of Dentistry, Melaka-Manipal Medical College among 3rd and 4th year BDS students. A total of 145 dental students, who consented, participate in the study. Students were divided into 14 groups. Nine online sessions followed by nine face-to-face discussions were held. Each session addressed topics related to oral lesions and orofacial pain with pharmacological applications. After each week, students were asked to reflect on blended learning. On completion of 9 weeks, reflections were collected and analyzed. Statistical Analysis: Qualitative analysis was done using thematic analysis model suggested by Braun and Clarke. Results: The four main themes were identified, namely, merits of blended learning, skill in writing prescription for oral diseases, dosages of drugs, and identification of strengths and weakness. In general, the participants had a positive feedback regarding blended learning. Students felt more confident in drug selection and prescription writing. They could recollect the doses better after the online and face-to-face sessions. Most interestingly, the students reflected that they are able to identify their strength and weakness after the blended learning sessions. Conclusions: Blended learning module was successfully implemented for reinforcing dental pharmacology. The results obtained in this study enable us to plan future comparative studies to know the effectiveness of blended learning in dental pharmacology. PMID:28031603

Relationships between leaf chlorophyll content and spectral reflectance and algorithms for non-destructive chlorophyll assessment in higher plant leaves.

PubMed

Gitelson, Anatoly A; Gritz, Yuri; Merzlyak, Mark N

2003-03-01

Leaf chlorophyll content provides valuable information about physiological status of plants. Reflectance measurement makes it possible to quickly and non-destructively assess, in situ, the chlorophyll content in leaves. Our objective was to investigate the spectral behavior of the relationship between reflectance and chlorophyll content and to develop a technique for non-destructive chlorophyll estimation in leaves with a wide range of pigment content and composition using reflectance in a few broad spectral bands. Spectral reflectance of maple, chestnut, wild vine and beech leaves in a wide range of pigment content and composition was investigated. It was shown that reciprocal reflectance (R lambda)-1 in the spectral range lambda from 520 to 550 nm and 695 to 705 nm related closely to the total chlorophyll content in leaves of all species. Subtraction of near infra-red reciprocal reflectance, (RNIR)-1, from (R lambda)-1 made index [(R lambda)(-1)-(RNIR)-1] linearly proportional to the total chlorophyll content in spectral ranges lambda from 525 to 555 nm and from 695 to 725 nm with coefficient of determination r2 > 0.94. To adjust for differences in leaf structure, the product of the latter index and NIR reflectance [(R lambda)(-1)-(RNIR)-1]*(RNIR) was used; this further increased the accuracy of the chlorophyll estimation in the range lambda from 520 to 585 nm and from 695 to 740 nm. Two independent data sets were used to validate the developed algorithms. The root mean square error of the chlorophyll prediction did not exceed 50 mumol/m2 in leaves with total chlorophyll ranged from 1 to 830 mumol/m2.

A total internal reflection-fluorescence correlation spectroscopy setup with pulsed diode laser excitation

NASA Astrophysics Data System (ADS)

Weger, Lukas; Hoffmann-Jacobsen, Kerstin

2017-09-01

Fluorescence correlation spectroscopy (FCS) measures fluctuations in a (sub-)femtoliter volume to analyze the diffusive behavior of fluorescent particles. This highly sensitive method has proven to be useful for the analysis of dynamic biological systems as well as in chemistry, physics, and material sciences. It is routinely performed with commercial fluorescence microscopes, which provide a confined observation volume by the confocal technique. The evanescent wave of total internal reflectance (TIR) is used in home-built systems to permit a surface sensitive FCS analysis. We present a combined confocal and TIR-FCS setup which uses economic low-power pulsed diode lasers for excitation. Excitation and detection are coupled to time-correlated photon counting hardware. This allows simultaneous fluorescence lifetime and FCS measurements in a surface-sensitive mode. Moreover, the setup supports fluorescence lifetime correlation spectroscopy at surfaces. The excitation can be easily switched between TIR and epi-illumination to compare the surface properties with those in liquid bulk. The capabilities of the presented setup are demonstrated by measuring the diffusion coefficients of a free dye molecule, a labeled polyethylene glycol, and a fluorescent nanoparticle in confocal as well as in TIR-FCS.

Analysis of Oblique Wave Interaction with a Comb-Type Caisson Breakwater

NASA Astrophysics Data System (ADS)

Wang, Xinyu; Liu, Yong; Liang, Bingchen

2018-04-01

This study develops an analytical solution for oblique wave interaction with a comb-type caisson breakwater based on linear potential theory. The fluid domain is divided into inner and outer regions according to the geometrical shape of breakwater. By using periodic boundary condition and separation of variables, series solutions of velocity potentials in inner and outer regions are developed. Unknown expansion coefficients in series solutions are determined by matching velocity and pressure of continuous conditions on the interface between two regions. Then, hydrodynamic quantities involving reflection coefficients and wave forces acting on breakwater are estimated. Analytical solution is validated by a multi-domain boundary element method solution for the present problem. Diffusion reflection due to periodic variations in breakwater shape and corresponding surface elevations around the breakwater are analyzed. Numerical examples are also presented to examine effects of caisson parameters on total wave forces acting on caissons and total wave forces acting on side plates. Compared with a traditional vertical wall breakwater, the wave force acting on a suitably designed comb-type caisson breakwater can be significantly reduced. This study can give a better understanding of the hydrodynamic performance of comb-type caisson breakwaters.

Evanescent Field Based Photoacoustics: Optical Property Evaluation at Surfaces

PubMed Central

Goldschmidt, Benjamin S.; Rudy, Anna M.; Nowak, Charissa A.; Tsay, Yowting; Whiteside, Paul J. D.; Hunt, Heather K.

2016-01-01

Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. Optical property evaluation of thin films and the surfaces of bulk materials is an important step in understanding new optical material systems and their applications. The method presented can estimate thickness, refractive index, and use absorptive properties of materials for detection. This metrology system uses evanescent field-based photoacoustics (EFPA), a field of research based upon the interaction of an evanescent field with the photoacoustic effect. This interaction and its resulting family of techniques allow the technique to probe optical properties within a few hundred nanometers of the sample surface. This optical near field allows for the highly accurate estimation of material properties on the same scale as the field itself such as refractive index and film thickness. With the use of EFPA and its sub techniques such as total internal reflection photoacoustic spectroscopy (TIRPAS) and optical tunneling photoacoustic spectroscopy (OTPAS), it is possible to evaluate a material at the nanoscale in a consolidated instrument without the need for many instruments and experiments that may be cost prohibitive. PMID:27500652

Spectral Mining for Discriminating Blood Origins in the Presence of Substrate Interference via Attenuated Total Reflection Fourier Transform Infrared Spectroscopy: Postmortem or Antemortem Blood?

PubMed

Takamura, Ayari; Watanabe, Ken; Akutsu, Tomoko; Ikegaya, Hiroshi; Ozawa, Takeaki

2017-09-19

Often in criminal investigations, discrimination of types of body fluid evidence is crucially important to ascertain how a crime was committed. Compared to current methods using biochemical techniques, vibrational spectroscopic approaches can provide versatile applicability to identify various body fluid types without sample invasion. However, their applicability is limited to pure body fluid samples because important signals from body fluids incorporated in a substrate are affected strongly by interference from substrate signals. Herein, we describe a novel approach to recover body fluid signals that are embedded in strong substrate interferences using attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy and an innovative multivariate spectral processing. This technique supported detection of covert features of body fluid signals, and then identified origins of body fluid stains on substrates. We discriminated between ATR FT-IR spectra of postmortem blood (PB) and those of antemortem blood (AB) by creating a multivariate statistics model. From ATR FT-IR spectra of PB and AB stains on interfering substrates (polyester, cotton, and denim), blood-originated signals were extracted by a weighted linear regression approach we developed originally using principal components of both blood and substrate spectra. The blood-originated signals were finally classified by the discriminant model, demonstrating high discriminant accuracy. The present method can identify body fluid evidence independently of the substrate type, which is expected to promote the application of vibrational spectroscopic techniques in forensic body fluid analysis.

Solar eclipses at high latitudes: ionospheric effects in the lower ionosphere

NASA Astrophysics Data System (ADS)

Cherniakov, S.

2017-12-01

The partial reflection facility of the Polar Geophysical Institute (the Tumanny observatory, 69.0N, 35.7E) has observed behavior of the high-latitude lower ionosphere during the 20 March 2015 total solar eclipse. There were several effects during the eclipse. At the heights of 60-80 km the ionosphere has shown the effect of a "short night", but at the higher altitudes local enhanced electron concentration had a wave-like form. Data received by the riometer of the Tumanny observatory have also shown wave-like behavior. The behavior can be explained by influence of acoustic-gravity waves which originated after cooling of the atmosphere during the lunar shadow supersonic movement, and transport processes during the eclipse. During the 21 August 2017 solar eclipse there was a substorm at the high latitudes. But after the end of the substorm in the region of the Tumanny observatory the observed amplitudes of the reflected waves had wave effects which could be connected with the coming waves from the region of the eclipse. The wave features were also shown in the behavior of the total electron content (TEC) of the lower ionosphere. During several solar eclipses it was implemented observations of lower ionosphere behavior by the partial reflection facility of the Tumanny observatory. The consideration of the lower ionosphere TEC had revealed common features in the TEC behavior during the eclipses. The photochemical theory of processes in the lower ionosphere is very complicated and up to now it is not completely developed. Therefore introduction of the effective coefficients determining the total speed of several important reactions has been widely adopted when modeling the D-region of the ionosphere. However, experimental opportunities for obtaining effective recombination coefficients are rather limited. One of the methods to estimate effective recombination coefficients uses the phenomenon of a solar eclipse. During solar eclipses at the partial reflection facility of the Tumanny observatory observations were carried out. It gave possibility to obtain the behavior of the electron concentration in time at the selected heights. Using the obtained experimental profiles, the effective recombination coefficients at the D-region heights of the ionosphere have been evaluated.

EFFECT OF CHERENKOV LIGHT POLARIZATION ON TOTAL REFLECTION COUNTER

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

Dowell, J.D.; Duteil, P.; Leontic, B.

1963-01-01

A rugged total internal reflection counter with a 3- to 5cm thick compact radiator was used at the CERN proton synchrotron for beam analysis. The threshold behavior of this counter was compared when filled with glycerol and with turpentine. Turpentine is optically active and rotates the plane of polarization about 7 un. Concent 85% /cm. Figures illustrate the effect of this polarization rotation. (A.G.W.)

Spectral measurements and analyses of atmospheric effects on remote sensor data

NASA Technical Reports Server (NTRS)

Hulstrom, R. L.

1975-01-01

The radiance as measured by a satellite remote sensor is determined by a number of different factors, including the intervening atmosphere, the target reflectivity characteristics, the characteristics of the total incident solar irradiance, and the incident solar irradiance/sensor viewing geometry. Measurement techniques and instrumentation are considered, taking into account total and diffuse solar irradiance, target reflectance/radiance, atmospheric optical depth/transmittance, and atmospheric path radiance.

A Two-stage Approach for Water Demand Prediction under Constrained total water use and Water Environmental Capacity

NASA Astrophysics Data System (ADS)

He, Y.; Xiaohong, C.; Lin, K.; Wang, Z.

2016-12-01

Water demand (WD) is the basis for water allocation (WA) because it can fully reflect the pressure on water resources from population and socioeconomic development. To deal with the great uncertainties and the absence of consideration of water environmental capacity (WEC) in traditional water demand prediction methods, e.g. Statistical models, System Dynamics and quota method, this study develops a two-stage approach to predict WD under constrained total water use from the perspective of ecological restraint. Regional total water demand (RTWD) is constrained by WEC, available water resources amount and total water use quota. Based on RTWD, WD is allocated in two stages according to the game theory, including predicting sub regional total water demand (SRWD) by calculating the sub region weights based on the selected indicators of socioeconomic development and predicting industrial water demand (IWD) according to the game theory. Taking the Dongjiang river basin, South China as an example of WD prediction, according to its constrained total water use quota and WEC, RTWD in 2020 is 9.83 billion m3, and IWD for agriculture, industry, service, ecology (off-stream), and domesticity are 2.32 billion m3, 3.79 billion m3, 0.75 billion m3 , 0.18 billion m3and 1.79 billion m3 respectively. The results from this study provide useful insights for effective water allocation under climate change and the strict policy of water resources management.

A rapid field test for the measurement of bovine serum immunoglobulin G using attenuated total reflectance infrared spectroscopy.

PubMed

Elsohaby, Ibrahim; Hou, Siyuan; McClure, J Trenton; Riley, Christopher B; Shaw, R Anthony; Keefe, Gregory P

2015-08-20

Following the recent development of a new approach to quantitative analysis of IgG concentrations in bovine serum using transmission infrared spectroscopy, the potential to measure IgG levels using technology and a device better designed for field use was investigated. A method using attenuated total reflectance infrared (ATR) spectroscopy in combination with partial least squares (PLS) regression was developed to measure bovine serum IgG concentrations. ATR spectroscopy has a distinct ease-of-use advantage that may open the door to routine point-of-care testing. Serum samples were collected from calves and adult cows, tested by a reference RID method, and ATR spectra acquired. The spectra were linked to the RID-IgG concentrations and then randomly split into two sets: calibration and prediction. The calibration set was used to build a calibration model, while the prediction set was used to assess the predictive performance and accuracy of the final model. The procedure was repeated for various spectral data preprocessing approaches. For the prediction set, the Pearson's and concordance correlation coefficients between the IgG measured by RID and predicted by ATR spectroscopy were both 0.93. The Bland Altman plot revealed no obvious systematic bias between the two methods. ATR spectroscopy showed a sensitivity for detection of failure of transfer of passive immunity (FTPI) of 88 %, specificity of 100 % and accuracy of 94 % (with IgG <1000 mg/dL as the FTPI cut-off value). ATR spectroscopy in combination with multivariate data analysis shows potential as an alternative approach for rapid quantification of IgG concentrations in bovine serum and the diagnosis of FTPI in calves.

Near-infrared and Mid-infrared Spectroscopic Techniques for a Fast and Nondestructive Quality Control of Thymi herba.

PubMed

Pezzei, Cornelia K; Schönbichler, Stefan A; Hussain, Shah; Kirchler, Christian G; Huck-Pezzei, Verena A; Popp, Michael; Krolitzek, Justine; Bonn, Günther K; Huck, Christian W

2018-04-01

In this study, novel near-infrared and attenuated total reflectance mid-infrared spectroscopic methods coupled with multivariate data analysis were established enabling the determination of thymol, rosmarinic acid, and the antioxidant capacity of Thymi herba. A new high-performance liquid chromatography method and UV-Vis spectroscopy were applied as reference methods. Partial least squares regressions were carried out as cross and test set validations. To reduce systematic errors, different data pretreatments, such as multiplicative scatter correction, 1st derivative, or 2nd derivative, were applied on the spectra. The performances of the two infrared spectroscopic techniques were evaluated and compared. In general, attenuated total reflectance mid-infrared spectroscopy demonstrated a slightly better predictive power (thymol: coefficient of determination = 0.93, factors = 3, ratio of performance to deviation = 3.94; rosmarinic acid: coefficient of determination = 0.91, factors = 3, ratio of performance to deviation = 3.35, antioxidant capacity: coefficient of determination = 0.87, factors = 2, ratio of performance to deviation = 2.80; test set validation) than near-infrared spectroscopy (thymol: coefficient of determination = 0.90, factors = 6, ratio of performance to deviation = 3.10; rosmarinic acid: coefficient of determination = 0.92, factors = 6, ratio of performance to deviation = 3.61, antioxidant capacity: coefficient of determination = 0.91, factors = 6, ratio of performance to deviation = 3.42; test set validation). The capability of infrared vibrational spectroscopy as a quick and simple analytical tool to replace conventional time and chemical consuming analyses for the quality control of T. herba could be demonstrated. Georg Thieme Verlag KG Stuttgart · New York.

Synchronous scattering and diffraction from gold nanotextured surfaces with structure factors

NASA Astrophysics Data System (ADS)

Gu, Min-Jhong; Lee, Ming-Tsang; Huang, Chien-Hsun; Wu, Chi-Chun; Chen, Yu-Bin

2018-05-01

Synchronous scattering and diffraction were demonstrated using reflectance from gold nanotextured surfaces at oblique (θi = 15° and 60°) incidence of wavelength λ = 405 nm. Two samples of unique auto-correlation functions were cost-effectively fabricated. Multiple structure factors of their profiles were confirmed with Fourier expansions. Bi-directional reflectance function (BRDF) from these samples provided experimental proofs. On the other hand, standard deviation of height and unique auto-correlation function of each sample were used to generate surfaces numerically. Comparing their BRDF with those of totally random rough surfaces further suggested that structure factors in profile could reduce specular reflection more than totally random roughness.

High performance liquid chromatographic assay for the quantitation of total glutathione in plasma

NASA Technical Reports Server (NTRS)

Abukhalaf, Imad K.; Silvestrov, Natalia A.; Menter, Julian M.; von Deutsch, Daniel A.; Bayorh, Mohamed A.; Socci, Robin R.; Ganafa, Agaba A.

2002-01-01

A simple and widely used homocysteine HPLC procedure was applied for the HPLC identification and quantitation of glutathione in plasma. The method, which utilizes SBDF as a derivatizing agent utilizes only 50 microl of sample volume. Linear quantitative response curve was generated for glutathione over a concentration range of 0.3125-62.50 micromol/l. Linear regression analysis of the standard curve exhibited correlation coefficient of 0.999. Limit of detection (LOD) and limit of quantitation (LOQ) values were 5.0 and 15 pmol, respectively. Glutathione recovery using this method was nearly complete (above 96%). Intra-assay and inter-assay precision studies reflected a high level of reliability and reproducibility of the method. The applicability of the method for the quantitation of glutathione was demonstrated successfully using human and rat plasma samples.

[Study on predicting sugar content and valid acidity of apples by near infrared diffuse reflectance technique].

PubMed

Liu, Yan-de; Ying, Yi-bin; Fu, Xia-ping

2005-11-01

The nondestructive method for quantifying sugar content (SC) and available acid (VA) of intact apples using diffuse near infrared reflectance and optical fiber sensing techniques were explored in the present research. The standard sample sets and prediction models were established by partial least squares analysis (PLS). A total of 120 Shandong Fuji apples were tested in the wave number of 12,500 - 4000 cm(-1) using Fourier transform near infrared spectroscopy. The results of the research indicated that the nondestructive quantification of SC and VA, gave a high correlation coefficient 0.970 and 0.906, a low root mean square error of prediction (RMSEP) 0.272 and 0.056 2, a low root mean square error of calibration (RMSEC) 0.261 and 0.0677, and a small difference between RMSEP and RMSEC 0.011 a nd 0.0115. It was suggested that the diffuse nearinfrared reflectance technique be feasible for nondestructive determination of apple sugar content in the wave number range of 10,341 - 5461 cm(-1) and for available acid in the wave number range of 10,341 - 3818 cm(-1).

Fertility and contraceptive adoption and discontinuation in rural Kenya.

PubMed

Ferguson, A G

1992-01-01

After a long period of slow progress, the recent uptake of contraceptive use in Kenya has been dramatic. This report describes adoption of a method and method switching and discontinuation among a cohort of married women aged 25-34 in two contrasting rural areas. A retrospective "fertility diary" completed by each woman provided information on spousal separation, reproductive status, and contraceptive use over a period of 46-48 months. Contraceptive prevalence rose rapidly over the period in both areas, with significant net adoption of injectables in both areas and of IUDs in one only. Method discontinuation was concentrated among users of pills, barrier methods, and "natural" methods, and only one-third of all discontinuations were voluntary. The wide differences between the two rural areas in contraceptive prevalence were not totally reflected in recent fertility levels, and the contribution of other proximate determinants of fertility, particularly postpartum amenorrhea and spousal separation, are discussed.

Method of Detecting Coliform Bacteria and Escherichia Coli Bacteria from Reflected Light

NASA Technical Reports Server (NTRS)

Vincent, Robert (Inventor)

2013-01-01

The present invention relates to a method of detecting coliform bacteria in water from reflected light and a method of detecting Eschericha Coli bacteria in water from reflected light, and also includes devices for the measurement, calculation and transmission of data relating to that method.

Assessing Reflection: Understanding Skill Development through Reflective Learning Journals

ERIC Educational Resources Information Center

Cathro, Virginia; O'Kane, Paula; Gilbertson, Deb

2017-01-01

Purpose: The purpose of this paper is to suggest ways in which business educators can interact successfully with reflective learning journals (RLJs). Specifically, the research was interested in how students used RLJs and how educators assessed these RLJs. Design/methodology/approach: In total, 31 RLJs, submitted as part of an international…

Student Teacher Reflective Writing: What Does It Reveal?

ERIC Educational Resources Information Center

Mena-Marcos, Juanjo; Garcia-Rodriguez, Maria-Luisa; Tillema, Harm

2013-01-01

Some researchers claim that reflection helps student teachers to better understand their practice teaching. This study aims to explore how deliberate reflection by student teachers is encouraged as a way to prepare, analyse and evaluate their practice. A total of 104 student teachers in primary education participated in this study during their…

Method for analysis dried vine fruits contaminated with ochratoxin A.

PubMed

Galvis-Sánchez, Andrea C; Barros, Antonio S; Delgadillo, Ivonne

2008-06-09

The EU maximum limit of 10 microg kg(-1) of OTA for dried vine fruits has been established since 2002 (European Commission, 2005). The presented work explore the capability of using Fourier infrared spectroscopy attenuated total reflection (FTIR-ATR) for the detection of ochratoxin A (OTA) in dried vine fruits in a range of concentration between 2 and 50 microg kg(-1) OTA. The method developed included a sample pretreatment using a C18 cartridge which was efficient for the isolation of the mycotoxin. The PLS1 analysis of the spectrum of sultanas spiked with different OTA concentrations showed a good correlation between the spectral data and reference concentration for OTA (R(2)=0.85).

The Influence of Collaborative Reflection and Think-Aloud Protocols on Pre-Service Teachers' Reflection: A Mixed Methods Approach

ERIC Educational Resources Information Center

Epler, Cory M.; Drape, Tiffany A.; Broyles, Thomas W.; Rudd, Rick D.

2013-01-01

The purpose of this mixed methods study was to determine if there are differences in pre-service teachers' depth of reflection when using a written self-reflection form, a written self-reflection form and a think-aloud protocol, and collaborative reflection. Twenty-six pre-service teachers were randomly assigned to fourteen teaching teams. The…

An Isometric Mapping Based Co-Location Decision Tree Algorithm

NASA Astrophysics Data System (ADS)

Zhou, G.; Wei, J.; Zhou, X.; Zhang, R.; Huang, W.; Sha, H.; Chen, J.

2018-05-01

Decision tree (DT) induction has been widely used in different pattern classification. However, most traditional DTs have the disadvantage that they consider only non-spatial attributes (ie, spectral information) as a result of classifying pixels, which can result in objects being misclassified. Therefore, some researchers have proposed a co-location decision tree (Cl-DT) method, which combines co-location and decision tree to solve the above the above-mentioned traditional decision tree problems. Cl-DT overcomes the shortcomings of the existing DT algorithms, which create a node for each value of a given attribute, which has a higher accuracy than the existing decision tree approach. However, for non-linearly distributed data instances, the euclidean distance between instances does not reflect the true positional relationship between them. In order to overcome these shortcomings, this paper proposes an isometric mapping method based on Cl-DT (called, (Isomap-based Cl-DT), which is a method that combines heterogeneous and Cl-DT together. Because isometric mapping methods use geodetic distances instead of Euclidean distances between non-linearly distributed instances, the true distance between instances can be reflected. The experimental results and several comparative analyzes show that: (1) The extraction method of exposed carbonate rocks is of high accuracy. (2) The proposed method has many advantages, because the total number of nodes, the number of leaf nodes and the number of nodes are greatly reduced compared to Cl-DT. Therefore, the Isomap -based Cl-DT algorithm can construct a more accurate and faster decision tree.

Simultaneous estimation of transcutaneous bilirubin, hemoglobin, and melanin based on diffuse reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Nishidate, Izumi; Abdul, Wares MD.; Ohtsu, Mizuki; Nakano, Kazuya; Haneishi, Hideaki

2018-02-01

We propose a method to estimate transcutaneous bilirubin, hemoglobin, and melanin based on the diffuse reflectance spectroscopy. In the proposed method, the Monte Carlo simulation-based multiple regression analysis for an absorbance spectrum in the visible wavelength region (460-590 nm) is used to specify the concentrations of bilirubin (Cbil), oxygenated hemoglobin (Coh), deoxygenated hemoglobin (Cdh), and melanin (Cm). Using the absorbance spectrum calculated from the measured diffuse reflectance spectrum as a response variable and the extinction coefficients of bilirubin, oxygenated hemoglobin, deoxygenated hemoglobin, and melanin, as predictor variables, multiple regression analysis provides regression coefficients. Concentrations of bilirubin, oxygenated hemoglobin, deoxygenated hemoglobin, and melanin, are then determined from the regression coefficients using conversion vectors that are numerically deduced in advance by the Monte Carlo simulations for light transport in skin. Total hemoglobin concentration (Cth) and tissue oxygen saturation (StO2) are simply calculated from the oxygenated hemoglobin and deoxygenated hemoglobin. In vivo animal experiments with bile duct ligation in rats demonstrated that the estimated Cbil is increased after ligation of bile duct and reaches to around 20 mg/dl at 72 h after the onset of the ligation, which corresponds to the reference value of Cbil measured by a commercially available transcutaneous bilirubin meter. We also performed in vivo experiments with rats while varying the fraction of inspired oxygen (FiO2). Coh and Cdh decreased and increased, respectively, as FiO2 decreased. Consequently, StO2 was dramatically decreased. The results in this study indicate potential of the method for simultaneous evaluation of multiple chromophores in skin tissue.

Embedded function methods for supersonic turbulent boundary layers

NASA Technical Reports Server (NTRS)

He, J.; Kazakia, J. Y.; Walker, J. D. A.

1990-01-01

The development of embedded functions to represent the mean velocity and total enthalpy distributions in the wall layer of a supersonic turbulent boundary layer is considered. The asymptotic scaling laws (in the limit of large Reynolds number) for high speed compressible flows are obtained to facilitate eventual implementation of the embedded functions in a general prediction method. A self-consistent asymptotic structure is derived, as well as a compressible law of the wall in which the velocity and total enthalpy are logarithmic within the overlap zone, but in the Howarth-Dorodnitsyn variable. Simple outer region turbulence models are proposed (some of which are modifications of existing incompressible models) to reflect the effects of compressibility. As a test of the methodology and the new turbulence models, a set of self-similar outer region profiles is obtained for constant pressure flow; these are then coupled with embedded functions in the wall layer. The composite profiles thus obtained are compared directly with experimental data and good agreement is obtained for flows with Mach numbers up to 10.

Reflections in computer modeling of rooms: Current approaches and possible extensions

NASA Astrophysics Data System (ADS)

Svensson, U. Peter

2005-09-01

Computer modeling of rooms is most commonly done by some calculation technique that is based on decomposing the sound field into separate reflection components. In a first step, a list of possible reflection paths is found and in a second step, an impulse response is constructed from the list of reflections. Alternatively, the list of reflections is used for generating a simpler echogram, the energy decay as function of time. A number of geometrical acoustics-based methods can handle specular reflections, diffuse reflections, edge diffraction, curved surfaces, and locally/non-locally reacting surfaces to various degrees. This presentation gives an overview of how reflections are handled in the image source method and variants of the ray-tracing methods, which are dominating today in commercial software, as well as in the radiosity method and edge diffraction methods. The use of the recently standardized scattering and diffusion coefficients of surfaces is discussed. Possibilities for combining edge diffraction, surface scattering, and impedance boundaries are demonstrated for an example surface. Finally, the number of reflection paths becomes prohibitively high when all such combinations are included as demonstrated for a simple concert hall model. [Work supported by the Acoustic Research Centre through NFR, Norway.

Wafer characteristics via reflectometry

DOEpatents

Sopori, Bhushan L.

2010-10-19

Various exemplary methods (800, 900, 1000, 1100) are directed to determining wafer thickness and/or wafer surface characteristics. An exemplary method (900) includes measuring reflectance of a wafer and comparing the measured reflectance to a calculated reflectance or a reflectance stored in a database. Another exemplary method (800) includes positioning a wafer on a reflecting support to extend a reflectance range. An exemplary device (200) has an input (210), analysis modules (222-228) and optionally a database (230). Various exemplary reflectometer chambers (1300, 1400) include radiation sources positioned at a first altitudinal angle (1308, 1408) and at a second altitudinal angle (1312, 1412). An exemplary method includes selecting radiation sources positioned at various altitudinal angles. An exemplary element (1650, 1850) includes a first aperture (1654, 1854) and a second aperture (1658, 1858) that can transmit reflected radiation to a fiber and an imager, respectfully.

A low order flow/acoustics interaction method for the prediction of sound propagation using 3D adaptive hybrid grids

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

Kallinderis, Yannis, E-mail: kallind@otenet.gr; Vitsas, Panagiotis A.; Menounou, Penelope

2012-07-15

A low-order flow/acoustics interaction method for the prediction of sound propagation and diffraction in unsteady subsonic compressible flow using adaptive 3-D hybrid grids is investigated. The total field is decomposed into the flow field described by the Euler equations, and the acoustics part described by the Nonlinear Perturbation Equations. The method is shown capable of predicting monopole sound propagation, while employment of acoustics-guided adapted grid refinement improves the accuracy of capturing the acoustic field. Interaction of sound with solid boundaries is also examined in terms of reflection, and diffraction. Sound propagation through an unsteady flow field is examined using staticmore » and dynamic flow/acoustics coupling demonstrating the importance of the latter.« less

Calculation of far-field scattering from nonspherical particles using a geometrical optics approach

NASA Technical Reports Server (NTRS)

Hovenac, Edward A.

1991-01-01

A numerical method was developed using geometrical optics to predict far-field optical scattering from particles that are symmetric about the optic axis. The diffractive component of scattering is calculated and combined with the reflective and refractive components to give the total scattering pattern. The phase terms of the scattered light are calculated as well. Verification of the method was achieved by assuming a spherical particle and comparing the results to Mie scattering theory. Agreement with the Mie theory was excellent in the forward-scattering direction. However, small-amplitude oscillations near the rainbow regions were not observed using the numerical method. Numerical data from spheroidal particles and hemispherical particles are also presented. The use of hemispherical particles as a calibration standard for intensity-type optical particle-sizing instruments is discussed.

ADEOS Total Ozone Mapping Spectrometer (TOMS) Data Products User's Guide

NASA Technical Reports Server (NTRS)

Krueger, A.; Bhartia, P. K.; McPeters, R.; Herman, J.; Wellemeyer, C.; Jaross, G.; Seftor, C.; Torres, O.; Labow, G.; Byerly, W.;

Earth Probe Total Ozone Mapping Spectrometer (TOMS) Data Product User's Guide

NASA Technical Reports Server (NTRS)

McPeters, R.; Bhartia, P. K.; Krueger, A.; Herman, J.; Wellemeyer, C.; Seftor, C.; Jaross, G.; Torres, O.; Moy, L.; Labow, G.;

Bidirectional reflectance distribution function of diffuse extreme ultraviolet scatterers and extreme ultraviolet baffle materials.

PubMed

Newell, M P; Keski-Kuha, R A

1997-08-01

Bidirectional reflectance distribution function (BRDF) measurements of a number of diffuse extreme ultraviolet (EUV) scatterers and EUV baffle materials have been performed with the Goddard EUV scatterometer. BRDF data are presented for white Spectralon SRS-99 at 121.6 nm; the data exhibit a non-Lambertian nature and a total hemispherical reflectance lower than 0.15. Data are also presented for an evaporated Cu black sample, a black Spectralon SRS-02 sample, and a Martin Optical Black sample at wavelengths of 58.4 and 121.6 nm and for angles of incidence of 15 degrees and 45 degrees. Overall Martin Optical Black exhibited the lowest BRDF characteristic, with a total hemispherical reflectance of the order of 0.01 and measured BRDF values as low as 2 x 10(-3) sr(-1).

Minimization of power consumption during charging of superconducting accelerating cavities

NASA Astrophysics Data System (ADS)

Bhattacharyya, Anirban Krishna; Ziemann, Volker; Ruber, Roger; Goryashko, Vitaliy

2015-11-01

The radio frequency cavities, used to accelerate charged particle beams, need to be charged to their nominal voltage after which the beam can be injected into them. The standard procedure for such cavity filling is to use a step charging profile. However, during initial stages of such a filling process a substantial amount of the total energy is wasted in reflection for superconducting cavities because of their extremely narrow bandwidth. The paper presents a novel strategy to charge cavities, which reduces total energy reflection. We use variational calculus to obtain analytical expression for the optimal charging profile. Energies, reflected and required, and generator peak power are also compared between the charging schemes and practical aspects (saturation, efficiency and gain characteristics) of power sources (tetrodes, IOTs and solid state power amplifiers) are also considered and analysed. The paper presents a methodology to successfully identify the optimal charging scheme for different power sources to minimize total energy requirement.

Probing Membrane Order and Topography in Supported Lipid Bilayers by Combined Polarized Total Internal Reflection Fluorescence-Atomic Force Microscopy

PubMed Central

Oreopoulos, John; Yip, Christopher M.

2009-01-01

Determining the local structure, dynamics, and conformational requirements for protein-protein and protein-lipid interactions in membranes is critical to understanding biological processes ranging from signaling to the translocating and membranolytic action of antimicrobial peptides. We report here the application of a combined polarized total internal reflection fluorescence microscopy-in situ atomic force microscopy platform. This platform's ability to image membrane orientational order was demonstrated on DOPC/DSPC/cholesterol model membranes containing the fluorescent membrane probe, DiI-C20 or BODIPY-PC. Spatially resolved order parameters and fluorophore tilt angles extracted from the polarized total internal reflection fluorescence microscopy images were in good agreement with the topographical details resolved by in situ atomic force microscopy, portending use of this technique for high-resolution characterization of membrane domain structures and peptide-membrane interactions. PMID:19254557

Magnetic Snell's law and spin-wave fiber with Dzyaloshinskii-Moriya interaction

NASA Astrophysics Data System (ADS)

Yu, Weichao; Lan, Jin; Wu, Ruqian; Xiao, Jiang

2016-10-01

Spin waves are collective excitations propagating in the magnetic medium with ordered magnetizations. Magnonics, utilizing the spin wave (magnon) as an information carrier, is a promising candidate for low-dissipation computation and communication technologies. We discover that, due to the Dzyaloshinskii-Moriya interaction, the scattering behavior of the spin wave at a magnetic domain wall follows a generalized Snell's law, where two magnetic domains work as two different mediums. Similar to optical total reflection that occurs at water-air interfaces, spin waves may experience total reflection at the magnetic domain walls when their incident angle is larger than a critical value. We design a spin-wave fiber using a magnetic domain structure with two domain walls, and demonstrate that such a spin-wave fiber can transmit spin waves over long distances by total internal reflections, in analogy to an optical fiber.

A Feasibility Study on Generation of Acoustic Waves Utilizing Evanescent Light

NASA Astrophysics Data System (ADS)

Matsuya, I.; Matozaki, K.; Kosugi, A.; Ihara, I.

2014-06-01

A new approach of generating acoustic waves utilizing evanescent light is presented. The evanescent light is a non-propagating electromagnetic wave that exhibits exponential decay with distance from the surface at which the total internal reflection of light is formed. In this research, the evanescent light during total internal reflection at prism surface is utilized for generating acoustic waves in aluminium and the feasibility for ultrasonic measurements is discussed. Pulsed Nd:YAG laser with 0.36 J/cm2 power density is used and the incident angle during the total internal reflection is arranged to be 69.0° for generating the evanescent light. It has been demonstrated that the amplitude of the acoustic waves by means of evanescent light is about 1/14 as large as the one generated by the conventional pulsed laser. This reveals the possibility of using a laser ultrasonic technique with near-field optics.

Surface-plasmon mediated total absorption of light into silicon.

PubMed

Yoon, Jae Woong; Park, Woo Jae; Lee, Kyu Jin; Song, Seok Ho; Magnusson, Robert

2011-10-10

We report surface-plasmon mediated total absorption of light into a silicon substrate. For an Au grating on Si, we experimentally show that a surface-plasmon polariton (SPP) excited on the air/Au interface leads to total absorption with a rate nearly 10 times larger than the ohmic damping rate of collectively oscillating free electrons in the Au film. Rigorous numerical simulations show that the SPP resonantly enhances forward diffraction of light to multiple orders of lossy waves in the Si substrate with reflection and ohmic absorption in the Au film being negligible. The measured reflection and phase spectra reveal a quantitative relation between the peak absorbance and the associated reflection phase change, implying a resonant interference contribution to this effect. An analytic model of a dissipative quasi-bound resonator provides a general formula for the resonant absorbance-phase relation in excellent agreement with the experimental results.

Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

DOEpatents

Pipino, Andrew Charles Rule

1999-11-16

An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

DOEpatents

Pipino, Andrew C. R.; Hudgens, Jeffrey W.

1999-08-24

An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

Understanding the power reflection and transmission coefficients of a plane wave at a planar interface

NASA Astrophysics Data System (ADS)

Ye, Qian; Jiang, Yikun; Lin, Haoze

2017-03-01

In most textbooks, after discussing the partial transmission and reflection of a plane wave at a planar interface, the power (energy) reflection and transmission coefficients are introduced by calculating the normal-to-interface components of the Poynting vectors for the incident, reflected and transmitted waves, separately. Ambiguity arises among students since, for the Poynting vector to be interpreted as the energy flux density, on the incident (reflected) side, the electric and magnetic fields involved must be the total fields, namely, the sum of incident and reflected fields, instead of the partial fields which are just the incident (reflected) fields. The interpretation of the cross product of partial fields as energy flux has not been obviously justified in most textbooks. Besides, the plane wave is actually an idealisation that is only ever found in textbooks, then what do the reflection and transmission coefficients evaluated for a plane wave really mean for a real beam of limited extent? To provide a clearer physical picture, we exemplify a light beam of finite transverse extent by a fundamental Gaussian beam and simulate its reflection and transmission at a planar interface. Due to its finite transverse extent, we can then insert the incident fields or reflected fields as total fields into the expression of the Poynting vector to evaluate the energy flux and then power reflection and transmission coefficients. We demonstrate that the power reflection and transmission coefficients of a beam of finite extent turn out to be the weighted sum of the corresponding coefficients for all constituent plane wave components that form the beam. The power reflection and transmission coefficients of a single plane wave serve, in turn, as the asymptotes for the corresponding coefficients of a light beam as its width expands infinitely.

Effect of polyvinylpyrrolidone content on alternating current conductivity of polyaniline

NASA Astrophysics Data System (ADS)

Megha, R.; Kumar, T. G. Naveen; Ravikiran, Y. T.; Prakash, H. G. Raj; Revanasiddappa, M.; Kumari, S. C. Vijaya

2018-05-01

In the present work, Polyaniline (PANI) and Polyaniline-polyvinylpyrrolidone (PANI-PVP) composites of two different weight percentages of PVP were synthesized separately by simple chemical polymerization method. The interaction between PANI and PVP in each of the composite was confirmed by Attenuated total reflection infrared spectroscopic (AT-IR) technique. The alternate current (AC) response characteristics at room temperature of PANI and the composites in the frequency range 50 Hz-1 MHz were comparatively studied. Both the composites have shown decreased conductivity as compared to that of PANI.

Tandem resonator reflectance modulator

DOEpatents

Fritz, I.J.; Wendt, J.R.

1994-09-06

A wide band optical modulator is grown on a substrate as tandem Fabry-Perot resonators including three mirrors spaced by two cavities. The absorption of one cavity is changed relative to the absorption of the other cavity by an applied electric field, to cause a change in total reflected light, as light reflecting from the outer mirrors is in phase and light reflecting from the inner mirror is out of phase with light from the outer mirrors. 8 figs.

Enhancing communication skills for telehealth: development and implementation of a Teach-Back intervention for a national maternal and child health helpline in Australia.

PubMed

Morony, Suzanne; Weir, Kristie; Duncan, Gregory; Biggs, Janice; Nutbeam, Don; Mccaffery, Kirsten J

2018-03-07

Telehealth professionals require advanced communication skills, in part to compensate for lack of visual cues. Teach-Back is a best practice communication technique that has been recommended but not previously evaluated for consumer telehealth. We aimed to implement Teach-Back at a national maternal and child health telephone helpline. We describe the intervention and report telenurse experiences learning to use Teach-Back. We identified barriers (time, knowledge, skills, beliefs) and enablers (self-reflection) to using Teach-Back, and developed a novel training program to address these, guided by the Theoretical Domains Framework. We engaged maternal and child health telenurses to participate in a "communication skills" study. The intervention had two key components: guided self-reflection and a Teach-Back skills workshop. For the duration of the 7-week study nurses completed brief online surveys following each call, reflecting on both the effectiveness of their communication and perceived caller understanding. At the end of each shift they reflected on what worked well. Teach-Back knowledge, skills, and beliefs were addressed in a 2-h workshop using videos, discussion, and role play. We explored nurses' experiences of the intervention in focus groups and interviews; and analysed transcripts and comments from the self-reflection surveys using the Framework method. This study forms part of a larger evaluation conducted in 2016. In total 16 nurses participated: 15 were trained in Teach-Back, and 13 participated in focus groups or interviews. All engaged with both self-reflection and Teach-Back, although to differing extents. Those who reported acquiring Teach-Back skills easily limited themselves to one or two Teach-Back phrases. Nurses reported that actively self-reflecting (including on what they did well) was useful both for developing Teach-Back skills and analysing effectiveness of the techniques. Most wanted more opportunity to learn how their colleagues manage Teach-Back in different situations, and more visual reminders to use Teach-Back. Our theory-informed intervention successfully enabled nurses to use Teach-Back. Guided self-reflection is a low-resource method aligned with nurse professional identity that can facilitate Teach-Back skills learning, and could also be applied to other advanced communication skills for telehealth. Listening to multiple workplace-specific examples of Teach-Back is recommended for future training. ACTRN12616000623493 Registered 15 May 2016. Retrospectively registered.

On the prediction of threshold friction velocity of wind erosion using soil reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Li, Junran; Flagg, Cody; Okin, Gregory S.; Painter, Thomas H.; Dintwe, Kebonye; Belnap, Jayne

2015-12-01

Current approaches to estimate threshold friction velocity (TFV) of soil particle movement, including both experimental and empirical methods, suffer from various disadvantages, and they are particularly not effective to estimate TFVs at regional to global scales. Reflectance spectroscopy has been widely used to obtain TFV-related soil properties (e.g., moisture, texture, crust, etc.), however, no studies have attempted to directly relate soil TFV to their spectral reflectance. The objective of this study was to investigate the relationship between soil TFV and soil reflectance in the visible and near infrared (VIS-NIR, 350-2500 nm) spectral region, and to identify the best range of wavelengths or combinations of wavelengths to predict TFV. Threshold friction velocity of 31 soils, along with their reflectance spectra and texture were measured in the Mojave Desert, California and Moab, Utah. A correlation analysis between TFV and soil reflectance identified a number of isolated, narrow spectral domains that largely fell into two spectral regions, the VIS area (400-700 nm) and the short-wavelength infrared (SWIR) area (1100-2500 nm). A partial least squares regression analysis (PLSR) confirmed the significant bands that were identified by correlation analysis. The PLSR further identified the strong relationship between the first-difference transformation and TFV at several narrow regions around 1400, 1900, and 2200 nm. The use of PLSR allowed us to identify a total of 17 key wavelengths in the investigated spectrum range, which may be used as the optimal spectral settings for estimating TFV in the laboratory and field, or mapping of TFV using airborne/satellite sensors.

Using empirical orthogonal functions from remote sensing reflectance spectra to predict various phytoplankton pigment concentrations in the Eastern Tropical Atlantic

NASA Astrophysics Data System (ADS)

Bracher, Astrid; Taylor, Bettina; Taylor, Marc; Steinmetz, Francois; Dinter, Tilman; Röttgers, Rüdiger

2014-05-01

Phytoplankton pigments play a major role in photosynthesis and photoprotection. Their composition and abundance give information on characteristics of a phytoplankton community in respect to its acclimation to light, overall biomass and composition of major phytoplankton groups. Most phytoplankton pigments can be measured by applying HPLC techniques to filtered water samples. This method like other mathods analysing water samples in the laboratory is time consuming and therefore only a limited number of samples can be obtained. In order to obtain information on phytoplankton pigment composition with a better temporal and spatial composition, the rationale was to develop a method to get from continuous optical measurements pigment concentrations. We have used remote sensing reflectances (RRS) derived from ship-based hyper-spectral underwater radiometric and from satellite MERIS measurements (using the POLYMER algorithm developed by Steinmetz et al. 2011), sampled in the Eastern Tropical Atlantic, to predict the water surface concentration of various pigments or pigment groups in this area. A statistical model based on Empirical Orthogonal Function (EOF) analysis of these RRS spectra was developed. Then subsequently linear models with measured (collocated) pigment concentrations as the response variable and EOF loadings as predictor variables were constructed. The model results, which have been verified by cross validation, show that from the ship-based RRS measurements the surface concentrations of a suite of pigments and pigment groups can be well predicted, even when only a multi-spectral resolution of RRS data is chosen. Based on the MERIS reflectance data, only concentrations of total chlorophyll-a (chl-a), monovinyl-chl-a and the groups of photoprotective and photosynthetic carotenoids can be obtained with high quality. The model constructed on the satellite reflectances as input was also applied to one month of MERIS POLYMER data to predict for the whole Eastern Tropical Atlantic area the concentration of those pigments. Finally, the potential, limitations and future perspectives for the application of our generic method are discussed.

Experimental determination of the viscous flow permeability of porous materials by measuring reflected low frequency acoustic waves

NASA Astrophysics Data System (ADS)

Berbiche, A.; Sadouki, M.; Fellah, Z. E. A.; Ogam, E.; Fellah, M.; Mitri, F. G.; Depollier, C.

2016-01-01

An acoustic reflectivity method is proposed for measuring the permeability or flow resistivity of air-saturated porous materials. In this method, a simplified expression of the reflection coefficient is derived in the Darcy's regime (low frequency range), which does not depend on frequency and porosity. Numerical simulations show that the reflection coefficient of a porous material can be approximated by its simplified expression obtained from its Taylor development to the first order. This approximation is good especially for resistive materials (of low permeability) and for the lower frequencies. The permeability is reconstructed by solving the inverse problem using waves reflected by plastic foam samples, at different frequency bandwidths in the Darcy regime. The proposed method has the advantage of being simple compared to the conventional methods that use experimental reflected data, and is complementary to the transmissivity method, which is more adapted to low resistive materials (high permeability).

Spectral Characteristics of Salinized Soils during Microbial Remediation Processes.

PubMed

Ma, Chuang; Shen, Guang-rong; Zhi, Yue-e; Wang, Zi-jun; Zhu, Yun; Li, Xian-hua

2015-09-01

In this study, the spectral reflectance of saline soils, the associated soil salt content (SSC) and the concentrations of salt ions were measured and analysed by tracing the container microbial remediation experiments for saline soil (main salt is sodium chloride) of Dongying City, Shandong Province. The sensitive spectral reflectance bands of saline soils to SSC, Cl- and Na+ in the process of microbial remediation were analysed. The average-dimension reduction of these bands was conducted by using a combination of correlation coefficient and decision coefficient, and by gradually narrowing the sampling interval method. Results showed that the tendency and magnitude of the average spectral reflectance in all bands of saline soils during the total remediation processes were nearly consistent with SSC and with Cl- coocentration, respectively. The degree of salinity of the soil, including SSC and salt ion concentrations, had a significant positive correlation with the spectral reflectance of all bands, particularly in the near-infrared band. The optimal spectral bands of SSC were 1370 to 1445 nm and 1447 to 1608 nm, whereas the optimal spectral bands of Cl- and Na+ were 1336 to 1461 nm and 1471 to 1561 nm, respectively. The relationship model among SSC, soil salt ion concentrations (Cl- and Na+) and soil spectral reflectance of the corresponding optimal spectral band was established. The largest R2 of relationship model between SSC and the average reflectance of associated optimal band reached to 0.95, and RMSEC and RMSEP were 1.076 and 0.591, respectively. Significant statistical analysis of salt factors and soil reflectance for different microbial remediation processes indicated that the spectral response characteristics and sensitivity of SSC to soil reflectance, which implied the feasibility of high spectrum test on soil microbial remediation monitoring, also provided the basis for quick nondestructive monitoring soil bioremediation process by soil spectral reflectance.

Core-shell silicon nanowire solar cells

PubMed Central

Adachi, M. M.; Anantram, M. P.; Karim, K. S.

2013-01-01

Silicon nanowires can enhance broadband optical absorption and reduce radial carrier collection distances in solar cell devices. Arrays of disordered nanowires grown by vapor-liquid-solid method are attractive because they can be grown on low-cost substrates such as glass, and are large area compatible. Here, we experimentally demonstrate that an array of disordered silicon nanowires surrounded by a thin transparent conductive oxide has both low diffuse and specular reflection with total values as low as < 4% over a broad wavelength range of 400 nm < λ < 650 nm. These anti-reflective properties together with enhanced infrared absorption in the core-shell nanowire facilitates enhancement in external quantum efficiency using two different active shell materials: amorphous silicon and nanocrystalline silicon. As a result, the core-shell nanowire device exhibits a short-circuit current enhancement of 15% with an amorphous Si shell and 26% with a nanocrystalline Si shell compared to their corresponding planar devices. PMID:23529071

Stray-light suppression in a reflecting white-light coronagraph

NASA Technical Reports Server (NTRS)

Romoli, Marco; Weiser, Heinz; Gardner, Larry D.; Kohl, John L.

1993-01-01

An analysis of stray-light suppression in the white-light channel of the Ultraviolet Coronagraph Spectrometer experiment for the Solar and Heliospheric Observatory is reported. The white-light channel consists of a reflecting telescope with external and internal occultation and a polarimeter section. Laboratory tests and analytical methods are used to perform the analysis. The various stray-light contributions are classified in two main categories: the contribution from sunlight that passes directly through the entrance aperture and the contribution of sunlight that is diffracted by the edges of the entrance aperture. Values of the stray-light contributions from various sources and the total stray-light level for observations at heliocentric heights from 1.4 to 5 solar radii are derived. Anticipated signal-to-stray-light ratios are presented together with the effective stray-light rejection by the polarimeter, demonstrating the efficacy of the stray-light suppression design.

Calculated photonic structures for infrared emittance control

NASA Astrophysics Data System (ADS)

Rung, Andreas; Ribbing, Carl G.

2002-06-01

Using an available program package based on the transfer-matrix method, we calculated the photonic band structure for two different structures: a quasi-three-dimensional crystal of square air rods in a high-index matrix and an opal structure of high-index spheres in a matrix of low index, epsilon = 1.5. The high index used is representative of gallium arsenide in the thermal infrared range. The geometric parameters of the rod dimension, sphere radius, and lattice constants were chosen to give total reflectance for normal incidence, i.e., minimum thermal emittance, in either one of the two infrared atmospheric windows. For these four photonic crystals, the bulk reflectance spectra and the wavelength-averaged thermal emittance as a function of crystal thickness were calculated. The results reveal that potentially useful thermal signature suppression is obtained for crystals as thin as 20-50 mum, i.e., comparable with that of a paint layer.

Total internal reflection-evanescent coupler for fiber-to-waveguide integration of planar optoelectric devices.

PubMed

Lu, Zhaolin; Prather, Dennis W

2004-08-01

We present a method for parallel coupling from a single-mode fiber, or fiber ribbon, into a silicon-on-insulator waveguide for integration with silicon optoelectronic circuits. The coupler incorporates the advantages of the vertically tapered waveguides and prism couplers, yet offers the flexibility of planar integration. The coupler can be fabricated by use of either wafer polishing technology or gray-scale photolithography. When optimal coupling is achieved in our experimental setup, the coupler can be packaged by epoxy bonding to form a fiber-waveguide parallel coupler or connector. Two-dimensional electromagnetic calculation predicts a coupling efficiency of 77% (- 1.14-dB insertion loss) for a silicon-to-silicon coupler with a uniform tunnel layer. The coupling efficiency is experimentally achieved to be 46% (-3.4-dB insertion loss), excluding the loss in silicon and the reflections from the input surface and the output facet.

Multilayer porous structures of HVPE and MOCVD grown GaN for photonic applications

NASA Astrophysics Data System (ADS)

Braniste, T.; Ciers, Joachim; Monaico, Ed.; Martin, D.; Carlin, J.-F.; Ursaki, V. V.; Sergentu, V. V.; Tiginyanu, I. M.; Grandjean, N.

2017-02-01

In this paper we report on a comparative study of electrochemical processes for the preparation of multilayer porous structures in hydride vapor phase epitaxy (HVPE) and metal organic chemical vapor phase deposition (MOCVD) grown GaN. It was found that in HVPE-grown GaN, multilayer porous structures are obtained due to self-organization processes leading to a fine modulation of doping during the crystal growth. However, these processes are not totally under control. Multilayer porous structures with a controlled design have been produced by optimizing the technological process of electrochemical etching in MOCVD-grown samples, consisting of five pairs of thin layers with alternating-doping profiles. The samples have been characterized by SEM imaging, photoluminescence spectroscopy, and micro-reflectivity measurements, accompanied by transfer matrix analysis and simulations by a method developed for the calculation of optical reflection spectra. We demonstrate the applicability of the produced structures for the design of Bragg reflectors.

Use of visible, near-infrared, and thermal infrared remote sensing to study soil moisture

NASA Technical Reports Server (NTRS)

Blanchard, M. B.; Greeley, R.; Goettelman, R.

1974-01-01

Two methods are described which are used to estimate soil moisture remotely using the 0.4- to 14.0 micron wavelength region: (1) measurement of spectral reflectance, and (2) measurement of soil temperature. The reflectance method is based on observations which show that directional reflectance decreases as soil moisture increases for a given material. The soil temperature method is based on observations which show that differences between daytime and nighttime soil temperatures decrease as moisture content increases for a given material. In some circumstances, separate reflectance or temperature measurements yield ambiguous data, in which case these two methods may be combined to obtain a valid soil moisture determination. In this combined approach, reflectance is used to estimate low moisture levels; and thermal inertia (or thermal diffusivity) is used to estimate higher levels. The reflectance method appears promising for surface estimates of soil moisture, whereas the temperature method appears promising for estimates of near-subsurface (0 to 10 cm).

Use of visible, near-infrared, and thermal infrared remote sensing to study soil moisture

NASA Technical Reports Server (NTRS)

Blanchard, M. B.; Greeley, R.; Goettelman, R.

1974-01-01

Two methods are used to estimate soil moisture remotely using the 0.4- to 14.0-micron wavelength region: (1) measurement of spectral reflectance, and (2) measurement of soil temperature. The reflectance method is based on observations which show that directional reflectance decreases as soil moisture increases for a given material. The soil temperature method is based on observations which show that differences between daytime and nighttime soil temperatures decrease as moisture content increases for a given material. In some circumstances, separate reflectance or temperature measurements yield ambiguous data, in which case these two methods may be combined to obtain a valid soil moisture determination. In this combined approach, reflectance is used to estimate low moisture levels; and thermal inertia (or thermal diffusivity) is used to estimate higher levels. The reflectance method appears promising for surface estimates of soil moisture, whereas the temperature method appears promising for estimates of near-subsurface (0 to 10 cm).

Telescope for x ray and gamma ray studies in astrophysics

NASA Technical Reports Server (NTRS)

Weaver, W. D.; Desai, Upendra D.

1993-01-01

Imaging of x-rays has been achieved by various methods in astrophysics, nuclear physics, medicine, and material science. A new method for imaging x-ray and gamma-ray sources avoids the limitations of previously used imaging devices. Images are formed in optical wavelengths by using mirrors or lenses to reflect and refract the incoming photons. High energy x-ray and gamma-ray photons cannot be reflected except at grazing angles and pass through lenses without being refracted. Therefore, different methods must be used to image x-ray and gamma-ray sources. Techniques using total absorption, or shadow casting, can provide images in x-rays and gamma-rays. This new method uses a coder made of a pair of Fresnel zone plates and a detector consisting of a matrix of CsI scintillators and photodiodes. The Fresnel zone plates produce Moire patterns when illuminated by an off-axis source. These Moire patterns are deconvolved using a stepped sine wave fitting or an inverse Fourier transform. This type of coder provides the capability of an instantaneous image with sub-arcminute resolution while using a detector with only a coarse position-sensitivity. A matrix of the CsI/photodiode detector elements provides the necessary coarse position-sensitivity. The CsI/photodiode detector also allows good energy resolution. This imaging system provides advantages over previously used imaging devices in both performance and efficiency.

Nanopipette Delivery of Individual Molecules to Cellular Compartments for Single-Molecule Fluorescence Tracking

PubMed Central

Bruckbauer, Andreas; James, Peter; Zhou, Dejian; Yoon, Ji Won; Excell, David; Korchev, Yuri; Jones, Roy; Klenerman, David

2007-01-01

We have developed a new method, using a nanopipette, for controlled voltage-driven delivery of individual fluorescently labeled probe molecules to the plasma membrane which we used for single-molecule fluorescence tracking (SMT). The advantages of the method are 1), application of the probe to predefined regions on the membrane; 2), release of only one or a few molecules onto the cell surface; 3), when combined with total internal reflection fluorescence microscopy, very low background due to unbound molecules; and 4), the ability to first optimize the experiment and then repeat it on the same cell. We validated the method by performing an SMT study of the diffusion of individual membrane glycoproteins labeled with Atto 647-wheat germ agglutin in different surface domains of boar spermatozoa. We found little deviation from Brownian diffusion with a mean diffusion coefficient of 0.79 ± 0.04 μm2/s in the acrosomal region and 0.10 ± 0.02 μm2/s in the postacrosomal region; this difference probably reflects different membrane structures. We also showed that we can analyze diffusional properties of different subregions of the cell membrane and probe for the presence of diffusion barriers. It should be straightforward to extend this new method to other probes and cells, and it can be used as a new tool to investigate the cell membrane. PMID:17631532

A high-gain, compact, nonimaging concentrator: RXI.

PubMed

Miñano, J C; Gonźlez, J C; Benítez, P

1995-12-01

The design procedure of a new nonimaging concentrator (called an RXI) is explained. Rays that impinge on the concentrator aperture, within the acceptance angle, are directed to the receiver by means of one refraction, one reflection, and one total internal reflection. The concentrator can be made as a single dielectric piece (in which the receiver is immersed) whose aspect ratio (thickness/aperture diameter) is close to 1/3. Ray-tracing analysis of a rotational symmetric RXI shows total transmissions of greater than 94.5% (no absorption or reflection losses are considered) when the acceptance angle of the incoming rays is small (<3°) and when the receiver area is the smallest possible (maximal concentration.).

Analysis of coke beverages by total-reflection X-ray fluorescence

NASA Astrophysics Data System (ADS)

Fernández-Ruiz, Ramón; von Bohlen, Alex; Friedrich K, E. Josue; Redrejo, M. J.

2018-07-01

The influence of the organic content, sample preparation process and the morphology of the depositions of two types of Coke beverage, traditional and light Coke, have been investigated by mean of Total-reflection X-ray Fluorescence (TXRF) spectrometry. Strong distortions of the nominal concentration values, up to 128% for P, have been detected in the analysis of traditional Coke by different preparation methods. These differences have been correlated with the edge X-ray energies of the elements analyzed being more pronounced for the lighter elements. The influence of the organic content (mainly sugar) was evaluated comparing traditional and light Coke analytical TXRF results. Three sample preparation methods have been evaluated as follows: direct TXRF analysis of the sample only adding internal standard, TXRF analysis after open vessel acid digestion and TXRF analysis after high pressure and temperature microwave-assisted acid digestion. Strong correlations were detected between quantitative results, methods of preparation and energies of the X-ray absorption edges of quantified elements. In this way, a decay behavior for the concentration differences between preparation methods and the energies of the X-ray absorption edges of each element were observed. The observed behaviors were modeled with exponential decay functions obtaining R2 correlation coefficients from 0.989 to 0.992. The strong absorption effect observed, and even possible matrix effect, can be explained by the inherent high organic content of the evaluated samples and also by the morphology and average thickness of the TXRF depositions observed. As main conclusion of this work, the analysis of light elements in samples with high organic content by TXRF, i.e. medical, biological, food or any other organic matrixes should be taken carefully. In any case, the direct analysis is not recommended and a previous microwave-assisted acid digestion, or similar, is mandatory, for the correct elemental quantification by TXRF.

Spectral reflectance inversion with high accuracy on green target

NASA Astrophysics Data System (ADS)

Jiang, Le; Yuan, Jinping; Li, Yong; Bai, Tingzhu; Liu, Shuoqiong; Jin, Jianzhou; Shen, Jiyun

2016-09-01

Using Landsat-7 ETM remote sensing data, the inversion of spectral reflectance of green wheat in visible and near infrared waveband in Yingke, China is studied. In order to solve the problem of lower inversion accuracy, custom atmospheric conditions method based on moderate resolution transmission model (MODTRAN) is put forward. Real atmospheric parameters are considered when adopting this method. The atmospheric radiative transfer theory to calculate atmospheric parameters is introduced first and then the inversion process of spectral reflectance is illustrated in detail. At last the inversion result is compared with simulated atmospheric conditions method which was a widely used method by previous researchers. The comparison shows that the inversion accuracy of this paper's method is higher in all inversion bands; the inversed spectral reflectance curve by this paper's method is more similar to the measured reflectance curve of wheat and better reflects the spectral reflectance characteristics of green plant which is very different from green artificial target. Thus, whether a green target is a plant or artificial target can be judged by reflectance inversion based on remote sensing image. This paper's research is helpful for the judgment of green artificial target hidden in the greenery, which has a great significance on the precise strike of green camouflaged weapons in military field.

In vivo spatial frequency domain spectroscopy of two layer media

NASA Astrophysics Data System (ADS)

Yudovsky, Dmitry; Nguyen, John Quan M.; Durkin, Anthony J.

2012-10-01

Monitoring of tissue blood volume and local oxygen saturation can inform the assessment of tissue health, healing, and dysfunction. These quantities can be estimated from the contribution of oxyhemoglobin and deoxyhemoglobin to the absorption spectrum of the dermis. However, estimation of blood related absorption in skin can be confounded by the strong absorption of melanin in the epidermis and epidermal thickness and pigmentation varies with anatomic location, race, gender, and degree of disease progression. Therefore, a method is desired that decouples the effect of melanin absorption in the epidermis from blood absorption in the dermis for a large range of skin types and thicknesses. A previously developed inverse method based on a neural network forward model was applied to simulated spatial frequency domain reflectance of skin for multiple wavelengths in the near infrared. It is demonstrated that the optical thickness of the epidermis and absorption and reduced scattering coefficients of the dermis can be determined independently and with minimal coupling. Then, the same inverse method was applied to reflectance measurements from a tissue simulating phantom and in vivo human skin. Oxygen saturation and total hemoglobin concentrations were estimated from the volar forearms of weakly and strongly pigmented subjects using a standard homogeneous model and the present two layer model.

Quantitative measurement of permeabilization of living cells by terahertz attenuated total reflection

NASA Astrophysics Data System (ADS)

Grognot, Marianne; Gallot, Guilhem

2015-09-01

Using Attenuated Total Reflection imaging technique in the terahertz domain, we demonstrate non-invasive, non-staining real time measurements of cytoplasm leakage during permeabilization of epithelial cells by saponin. The terahertz signal is mostly sensitive to the intracellular protein concentration in the cells, in a very good agreement with standard bicinchoninic acid protein measurements. It opens the way to in situ real time dynamics of protein content and permeabilization in live cells.

Total internal reflection-based side-pumping configuration for terawatt ultraviolet amplifier and laser oscillator development

NASA Astrophysics Data System (ADS)

Cadatal-Raduban, Marilou; Pham, Minh Hong; Pham, Duong Van; Bui, Duong Thi Thuy; Yamanoi, Kohei; Takeda, Kohei; Empizo, Melvin John F.; Mui, Luong Viet; Shimizu, Toshihiko; Nguyen, Hung Dai; Sarukura, Nobuhiko; Fukuda, Tsuguo

2018-06-01

A two-side-pumping scheme that is based on total internal reflection in a diamond-cut Ce3+:LiCaAlF6 crystal suitable for the development of an ultraviolet laser and femtosecond amplifier system is proposed. Experimental fluorescence images and lasing results that demonstrate total internal reflection of the excitation beam using this diamond-cut crystal are presented. Calculations for the optimized crystal geometry that facilitate high extraction efficiency and homogeneity of the absorbed excitation beam are also discussed. About 50% increase in extraction efficiency compared to previously reported chirped-pulse femtosecond ultraviolet amplifier operating at 50-GW peak power is expected using this total internal reflection-based two-side-pumping configuration and a diamond-cut Ce3+:LiCaAlF6 crystal with a geometry of {φ _1} = 103°, {φ _2} = {φ _4} = 82°, {φ _3} = 93°, a length of 1.23 cm, a height of 2 cm, and an absorption coefficient of 1.5 cm-1. Our results can be used as a guide during the crystal growth process by providing the appropriate crystal geometry and size for a particular absorption coefficient to achieve high extraction efficiency. With the appropriate crystal combined with multiple-beam pumping afforded by the side-pumping scheme, the development of an all-solid-state ultraviolet laser operating at terawatt level would be within reach.

Determination of germination quality of cucumber (Cucumis sativus) seed by LED-induced hyperspectral reflectance imaging

USDA-ARS?s Scientific Manuscript database

Purpose: We developed a viability evaluation method for cucumber (Cucumis sativus) seed using hyperspectral reflectance imaging. Methods: Reflectance spectra of cucumber seeds in the 400 to 1000 nm range were collected from hyperspectral reflectance images obtained using blue, green, and red LED ill...

Transverse shifts of a light beam reflected from a uniaxially anisotropic chiral slab

NASA Astrophysics Data System (ADS)

Xu, Guoding; Li, Jun; Xiao, Yuting; Mao, Hongmin; Sun, Jian; Pan, Tao

2015-01-01

We study for the first time the transverse shifts of a Gaussian beam reflected from a uniaxially anisotropic chiral (UAC) slab, where the chirality appears only in one direction and the host medium is a uniaxial crystal or an electric plasma. The results indicate that the transverse shifts are closely related to the propagation behaviors of the eigenwaves in the slab. Specifically, when one or both of the eigenwaves are totally reflected at the second interface of the slab, the spatial transverse shift becomes resonances but is not enhanced; when one eigenwave is totally reflected at the first interface and the other is transmitted at the second interface, the larger and negative transverse shifts can be obtained. The propagation behaviors of the eigenwaves in the UAC slab provide more abundant information about the transverse shifts than in a single interface structure.

Spectral Neugebauer-based color halftone prediction model accounting for paper fluorescence.

PubMed

Hersch, Roger David

2014-08-20

We present a spectral model for predicting the fluorescent emission and the total reflectance of color halftones printed on optically brightened paper. By relying on extended Neugebauer models, the proposed model accounts for the attenuation by the ink halftones of both the incident exciting light in the UV wavelength range and the emerging fluorescent emission in the visible wavelength range. The total reflectance is predicted by adding the predicted fluorescent emission relative to the incident light and the pure reflectance predicted with an ink-spreading enhanced Yule-Nielsen modified Neugebauer reflectance prediction model. The predicted fluorescent emission spectrum as a function of the amounts of cyan, magenta, and yellow inks is very accurate. It can be useful to paper and ink manufacturers who would like to study in detail the contribution of the fluorescent brighteners and the attenuation of the fluorescent emission by ink halftones.

Infrared analysis of polyethylene wear specimens using attenuated total reflection spectroscopy. [effects of radiation on the surface properties of materials for total joint protheses

NASA Technical Reports Server (NTRS)

Jones, W. R.; Lauer, J. L.

1979-01-01

Attenuated total reflection infrared spectroscopy was used to analyze ultrahigh molecular weight polyethylene wear test specimens. Three different specimens were analyzed. One specimen was gamma irradiated to a dose of 5.0 MRad, another to a dose of 2.5 MRad, and the final specimen was unirradiated. There was no conclusive evidence of chemical changes (i.e., unsaturation or oxidation) in the surface regions of any of the polyethylene samples. Therefore, it was concluded that the gamma irradiation sterilization procedure shoud not alter the boundary lubricating properties of the polyethylene.

Classification of corn kernels contaminated with aflatoxins using fluorescence and reflectance hyperspectral images analysis

NASA Astrophysics Data System (ADS)

Zhu, Fengle; Yao, Haibo; Hruska, Zuzana; Kincaid, Russell; Brown, Robert; Bhatnagar, Deepak; Cleveland, Thomas

2015-05-01

Aflatoxins are secondary metabolites produced by certain fungal species of the Aspergillus genus. Aflatoxin contamination remains a problem in agricultural products due to its toxic and carcinogenic properties. Conventional chemical methods for aflatoxin detection are time-consuming and destructive. This study employed fluorescence and reflectance visible near-infrared (VNIR) hyperspectral images to classify aflatoxin contaminated corn kernels rapidly and non-destructively. Corn ears were artificially inoculated in the field with toxigenic A. flavus spores at the early dough stage of kernel development. After harvest, a total of 300 kernels were collected from the inoculated ears. Fluorescence hyperspectral imagery with UV excitation and reflectance hyperspectral imagery with halogen illumination were acquired on both endosperm and germ sides of kernels. All kernels were then subjected to chemical analysis individually to determine aflatoxin concentrations. A region of interest (ROI) was created for each kernel to extract averaged spectra. Compared with healthy kernels, fluorescence spectral peaks for contaminated kernels shifted to longer wavelengths with lower intensity, and reflectance values for contaminated kernels were lower with a different spectral shape in 700-800 nm region. Principal component analysis was applied for data compression before classifying kernels into contaminated and healthy based on a 20 ppb threshold utilizing the K-nearest neighbors algorithm. The best overall accuracy achieved was 92.67% for germ side in the fluorescence data analysis. The germ side generally performed better than endosperm side. Fluorescence and reflectance image data achieved similar accuracy.

The Direct Lighting Computation in Global Illumination Methods

NASA Astrophysics Data System (ADS)

Wang, Changyaw Allen

1994-01-01

Creating realistic images is a computationally expensive process, but it is very important for applications such as interior design, product design, education, virtual reality, and movie special effects. To generate realistic images, state-of-art rendering techniques are employed to simulate global illumination, which accounts for the interreflection of light among objects. In this document, we formalize the global illumination problem into a eight -dimensional integral and discuss various methods that can accelerate the process of approximating this integral. We focus on the direct lighting computation, which accounts for the light reaching the viewer from the emitting sources after exactly one reflection, Monte Carlo sampling methods, and light source simplification. Results include a new sample generation method, a framework for the prediction of the total number of samples used in a solution, and a generalized Monte Carlo approach for computing the direct lighting from an environment which for the first time makes ray tracing feasible for highly complex environments.

Diffuse reflectance startigraphy - a new method in the study of loess (?)

NASA Astrophysics Data System (ADS)

József, Szeberényi; Balázs, Bradák; Klaudia, Kiss; József, Kovács; György, Varga; Réka, Balázs; Viczián, István

2017-04-01

The different varieties of loess (and intercalated paleosol layers) together constitute one of the most widespread terrestrial sediments, which was deposited, altered, and redeposited in the course of the changing climatic conditions of the Pleistocene. To reveal more information about Pleistocene climate cycles and/or environments the detailed lithostratigraphical subdivision and classification of the loess variations and paleosols are necessary. Beside the numerous method such as various field measurements, semi-quantitative tests and laboratory investigations, diffuse reflectance spectroscopy (DRS) is one of the well applied method on loess/paleosol sequences. Generally, DRS has been used to separate the detrital and pedogenic mineral component of the loess sections by the hematite/goethite ratio. DRS also has been applied as a joint method of various environmental magnetic investigations such as magnetic susceptibility- and isothermal remanent magnetization measurements. In our study the so-called "diffuse reflectance stratigraphy method" were developed. At First, complex mathematical method was applied to compare the results of the spectral reflectance measurements. One of the most preferred multivariate methods is cluster analysis. Its scope is to group and compare the loess variations and paleosol based on the similarity and common properties of their reflectance curves. In the Second, beside the basic subdivision of the profiles by the different reflectance curves of the layers, the most characteristic wavelength section of the reflectance curve was determined. This sections played the most important role during the classification of the different materials of the section. The reflectance value of individual samples, belonged to the characteristic wavelength were depicted in the function of depth and well correlated with other proxies like grain size distribution and magnetic susceptibility data. The results of the correlation showed the significance of the "combined reflectance stratigraphy" as a stratigraphical method and as an environmental proxy also.

Critically Reflective Leadership

ERIC Educational Resources Information Center

Cunningham, Christine L.

2012-01-01

Critical Reflective Practice (CRP) has a proven reputation as a method for teacher-researchers in K-12 classrooms, but there have been few published examples of this method being used to document school leaders' work-based practice. This paper outlines adaptations made by the author from an original CRP method to a Critically Reflective Leadership…

A protocol for EBT3 radiochromic film dosimetry using reflection scanning

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

Papaconstadopoulos, Pavlos, E-mail: pavpapac@gmail.com; Hegyi, Gyorgy; Seuntjens, Jan

2014-12-15

Purpose: To evaluate the performance of the EBT3 radiochromic film dosimetry system using reflection measurements and to suggest a calibration protocol for precise and accurate reflection film dosimetry. Methods: A set of 14 Gafchromic EBT3 film pieces were irradiated to various doses ranging from 0 to 8 Gy and subsequently scanned using both the reflection and transmission mode. Scanning resolution varied from 50 to 508 dpi (0.5–0.05 mm/pixel). Both the red and green color channels of scanned images were used to relate the film response to the dose. A sensitivity, uncertainty, and accuracy analysis was performed for all scanning modesmore » and color channels. The total uncertainty, along with the fitting and experimental uncertainty components, was identified and analyzed. A microscope resolution target was used to evaluate possible resolution losses under reflection scanning. The calibration range was optimized for reflection scanning in the low (<2 Gy) and high (>2 Gy) dose regions based on the reported results. Results: Reflection scanning using the red channel exhibited the highest sensitivity among all modes, being up to 150% higher than transmission mode in the red channel for the lowest dose level. Furthermore, there was no apparent loss in resolution between the two modes. However, higher uncertainties and reduced accuracy were observed for the red channel under reflection mode, especially at dose levels higher than 2 Gy. These uncertainties were mainly attributed to saturation effects which were translated in poor fitting results. By restricting the calibration to the 0–2 Gy dose range, the situation is reversed and the red reflection mode was superior to the transmission mode. For higher doses, the green channel in reflection mode presented comparable results to the red transmission. Conclusions: A two-color reflection scanning protocol can be suggested for EBT3 radiochromic film dosimetry using the red channel for doses less than 2 Gy and the green channel for higher doses. The precision and accuracy are significantly improved in the low dose region following such a protocol.« less

Novel joint selection methods can reduce sample size for rheumatoid arthritis clinical trials with ultrasound endpoints.

PubMed

Allen, John C; Thumboo, Julian; Lye, Weng Kit; Conaghan, Philip G; Chew, Li-Ching; Tan, York Kiat

2018-03-01

To determine whether novel methods of selecting joints through (i) ultrasonography (individualized-ultrasound [IUS] method), or (ii) ultrasonography and clinical examination (individualized-composite-ultrasound [ICUS] method) translate into smaller rheumatoid arthritis (RA) clinical trial sample sizes when compared to existing methods utilizing predetermined joint sites for ultrasonography. Cohen's effect size (ES) was estimated (ES^) and a 95% CI (ES^L, ES^U) calculated on a mean change in 3-month total inflammatory score for each method. Corresponding 95% CIs [nL(ES^U), nU(ES^L)] were obtained on a post hoc sample size reflecting the uncertainty in ES^. Sample size calculations were based on a one-sample t-test as the patient numbers needed to provide 80% power at α = 0.05 to reject a null hypothesis H 0 : ES = 0 versus alternative hypotheses H 1 : ES = ES^, ES = ES^L and ES = ES^U. We aimed to provide point and interval estimates on projected sample sizes for future studies reflecting the uncertainty in our study ES^S. Twenty-four treated RA patients were followed up for 3 months. Utilizing the 12-joint approach and existing methods, the post hoc sample size (95% CI) was 22 (10-245). Corresponding sample sizes using ICUS and IUS were 11 (7-40) and 11 (6-38), respectively. Utilizing a seven-joint approach, the corresponding sample sizes using ICUS and IUS methods were nine (6-24) and 11 (6-35), respectively. Our pilot study suggests that sample size for RA clinical trials with ultrasound endpoints may be reduced using the novel methods, providing justification for larger studies to confirm these observations. © 2017 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.

Increased efficiency with surface texturing in ITO/InP solar cells

NASA Technical Reports Server (NTRS)

Jenkins, Phillip; Landis, Geoffrey A.; Fatemi, Navid; Li, Xiaonan; Scheiman, David; Bailey, Sheila

1992-01-01

Optimization of an InP solar cell with a V-grooved surface is discussed. Total internal reflection in the coverglass reduces surface reflection and can recover light reflected from the front metallization. Results from the first ITO/InP solar cells on low-angle V-grooved substrates are presented, showing a 5.8 percent increase in current.

Assessment of Various Organic Matter Properties by Infrared Reflectance Spectroscopy of Sediments and Filters

NASA Astrophysics Data System (ADS)

Alaoui, G.; Leger, M.; Gagne, J.; Tremblay, L.

2009-05-01

The goal of this work was to evaluate the capability of infrared reflectance spectroscopy for a fast quantification of the elemental and molecular compositions of sedimentary and particulate organic matter (OM). A partial least-squares (PLS) regression model was used for analysis and values were compared to those obtained by traditional methods (i.e., elemental, humic and HPLC analyses). PLS tools are readily accessible from software such as GRAMS (Thermo-Fisher) used in spectroscopy. This spectroscopic-chemometric approach has several advantages including its rapidity and use of whole unaltered samples. To predict properties, a set of infrared spectra from representative samples must first be fitted to form a PLS calibration model. In this study, a large set (180) of sediments and particles on GFF filters from the St. Lawrence estuarine system were used. These samples are very heterogenous (e.g., various tributaries, terrigenous vs. marine, events such as landslides and floods) and thus represent a challenging test for PLS prediction. For sediments, the infrared spectra were obtained with a diffuse reflectance, or DRIFT, accessory. Sedimentary carbon, nitrogen, humic substance contents as well as humic substance proportions in OM and N:C ratios were predicted by PLS. The relative root mean square error of prediction (%RMSEP) for these properties were between 5.7% (humin content) and 14.1% (total humic substance yield) using the cross-validation, or leave-one out, approach. The %RMSEP calculated by PLS for carbon content was lower with the PLS model (7.6%) than with an external calibration method (11.7%) (Tremblay and Gagné, 2002, Anal. Chem., 74, 2985). Moreover, the PLS approach does not require the extraction of POM needed in external calibration. Results highlighted the importance of using a PLS calibration set representative of the unknown samples (e.g., same area). For filtered particles, the infrared spectra were obtained using a novel approach based on attenuated total reflectance, or ATR, allowing the direct analysis of the filters. In addition to carbon and nitrogen contents, amino acid and muramic acid (a bacterial biomarker) yields were predicted using PLS. Calculated %RMSEP varied from 6.4% (total amino acid content) to 18.6% (muramic acid content) with cross-validation. PLS regression modeling does not require a priori knowledge of the spectral bands associated with the properties to be predicted. In turn, the spectral regions that give good PLS predictions provided valuable information on band assignment and geochemical processes. For instance, nitrogen and humin contents were greatly determined by an absorption band caused by aluminosilicate OH group. This supports the idea that OM-clay interactions, important in humin formation and OM preservation, are mediated by nitrogen-containing groups.

COMPARISON OF METHODS FOR ESTIMATING CONTEMPORARY COSTS: AN APPLICATION TO LIVER TRANSPLANTATION IN THE UNITED KINGDOM.

PubMed

Singh, Jeshika; Longworth, Louise

2017-01-01

Our study addresses the important issue of estimating treatment costs from historical data. It is a problem frequently faced by health technology assessment analysts. We compared four approaches used to estimate current costs when good quality contemporary data are not available using liver transplantation as an example. First, the total cost estimates extracted for patients from a cohort study, conducted in the 1990s, were inflated using a published inflation multiplier. Second, resource use estimates from the cohort study were extracted for hepatitis C patients and updated using current unit costs. Third, expert elicitation was carried out to identify changes in clinical practice over time and quantify current resource use. Fourth, routine data on resource use were obtained from National Health Service Blood and Transplant (NHSBT). The first two methods did not account for changes in clinical practice. Also the first was not specific to hepatitis patients. The use of experts confirmed significant changes in clinical practice. However, the quantification of resource use using experts is challenging as clinical specialists may not have a complete overview of clinical pathway. The NHSBT data are the most accurate reflection of transplantation and posttransplantation phase; however, data were not available for the whole pathway of care. The best estimate of total cost, combining NHSBT data and expert elicitation, is £121,211. Observational data from routine care are potentially the most reliable reflection of current resource use. Efforts should be made to make such data readily available and accessible to researchers. Expert elicitation provided reasonable estimates.

Current Understandings of the Research-Practice Gap From the Viewpoint of Complementary Medicine Academics: A Mixed-Method Investigation.

PubMed

Leach, Matthew J; Tucker, Basil

Research plays an important role in advancing health and healthcare. However, much research evidence is not reflected in contemporary complementary and alternative medicine (CAM) practice. Understanding and addressing the reasons for this research-practice gap may have positive implications for quality of care. To shed light on the gap between research and CAM practice. Descriptive cross-sectional, mixed-method study. A total of 126 senior CAM academics across Australasia, Europe, UK, and North America. Participants completed a 30-item online survey and a semi-structured interview; both of which explored the research-practice gap in CAM. A total of 43 (34%) academics completed the survey, with 29 (67%) respondents undergoing an interview. There was general agreement among respondents that CAM research should be informed by practice, and practice informed by research; however, most agreed that this did not reflect the current situation. Translational issues were perceived to be the primary reason for the research-practice gap in CAM. Suggested strategies for closing the gap focussed mostly around improving CAM student/practitioner education and training, and researcher-practitioner engagement and collaboration. Study findings point toward the presence of a research-practice gap in CAM, with several factors likely to be instrumental in sustaining this gap. Attention now needs to focus on understanding the views of CAM clinicians on this issue. Insights gained from this research will help inform the development of a multi-modal strategy that will effectively target the barriers to change in order to bring CAM research and practice closer together. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparative study of Fourier transform infrared spectroscopy in transmission, attenuated total reflection, and total reflection modes for the analysis of plastics in the cultural heritage field.

PubMed

Picollo, Marcello; Bartolozzi, Giovanni; Cucci, Costanza; Galeotti, Monica; Marchiafava, Veronica; Pizzo, Benedetto

2014-01-01

This study was completed within the framework of two research projects dealing with the conservation of contemporary artworks. The first is the Seventh Framework Project (FP7) of the European Union, Preservation of Plastic ARTefacts in Museum Collections (POPART), spanning years 2008-2012, and the second is the Italian project funded by the Tuscan Region, Preventive Conservation of Contemporary Art (Conservazione Preventiva dell'Arte Contemporanea (COPAC)), spanning 2011-2013. Both of these programs pointed out the great importance of having noninvasive and portable analytical techniques that can be used to investigate and characterize modern and contemporary artworks, especially those consisting of synthetic polymers. Indeed, despite the extensive presence of plastics in museum collections, there is still a lack of analytical tools for identifying, characterizing, and setting up adequate conservation strategies for these materials. In this work, the potentials of in situ and noninvasive Fourier transform infrared (FT-IR) spectroscopy, implemented by means of portable devices that operate in reflection mode, are investigated with a view to applying the results in large-scale surveys of plastic objects in museums. To this end, an essential prerequisite are the reliability of spectral data acquired in situ and the availability of spectral databases acquired from reference materials. A collection of polymeric samples, which are available commercially as ResinKit, was analyzed to create a reference spectral archive. All the spectra were recorded using three FT-IR configurations: transmission (trans), attenuated total reflection (ATR), and total reflection (TR). A comparative evaluation of the data acquired using the three instrumental configurations is presented, together with an evaluation of the similarity percentages and a discussion of the critical cases.

DIRC Dreams: Research Directions for the Next Generation of Internally Reflected Imaging Counters

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

Ratcliff, Blair N.

1999-08-17

Some conceptual design features of the total internally reflecting,imaging Cherenkov counter (DIRC) are described. Limits of the DIRC approach to particle identification, and a few features of alternative DIRC designs, are briefly explored.

O the Determination of the Complex Refractive Index of Powdered Materials in the 9 TO 11 Micrometer Spectral Region Utilizing AN Attenuated Total Reflectance Technique.

NASA Astrophysics Data System (ADS)

Gillespie, James Bryce

1982-03-01

A specific method of determining the complex refractive index of powdered materials using attenuated total reflectance (ATR) spectroscopy was investigated. A very precise laser/goniometric ATR system was assembled and applied to powdered samples of carbon blacks, graphite, kaolin clay, quartz, calcite, and sodalime glass beads. The reflectivity data fell into two categories: (1) data representative of a medium having a unique effective refractive index and (2) data representative of a scattering medium having no unique refractive index. Data of the first kind were obtained from all the carbon black, graphite, and kaolin clay samples. The Fahrenfort-Visser solution of the Fresnel equations was applied to the goniometric reflectivity data for these samples to obtain the complex refractive index of these effective media. The complex refractive index obtained in this manner is not that of the bulk material but is instead a value which may be related to the bulk material value through some refractive index mixing rule. A systematic experiment using carbon black of particle size 0.0106 mm diameter was conducted to determine the applicability of several mixture rules for the volume packing fraction range of .2 to .6 which is most often encountered. The Bruggemann effective medium theory produced credible results while the Lorentz-Lorenz rule and the empirical Biot-Arago rule were invalid in this volume packing region. The Bruggemann rule was applied to lampblack, Mogul-L carbon black, graphite, and kaolin clay to obtain the complex refractive indices of these materials from the ATR spectroscopy data. Goniometric reflectivity data representative of an inhomogeneous scattering medium were obtained from all the powdered quartz, powdered calcite, and sodalime glass beads samples. These samples all contained particles with diameters nearly as large as the wavelength. These data demonstrate that the ATR technique, coupled with an effective medium analysis, may be used to obtain optical constants of powdered materials only when the particles are small compared to the wavelength.

Dielectric compound parabolic concentrating solar collector with a frustrated total internal reflection absorber.

PubMed

Hull, J R

1989-01-01

Coupling a dielectric compound parabolic concentrator (DCPC) to an absorber across a vacuum gap by means of frustrated total internal reflection (FTIR) can theoretically approach the maximum concentration permitted by physical laws, thus allowing higher radiative fluxes in thermal applications. The calculated optical performance of 2-D DCPCs with FTIR absorbers indicates that the ratio of gap thickness to optical wavelength must be <0.22 before the optical performance of the DCPC is superior to that of the nondielectric CPC.

Kinematic analysis of hip and knee rotation and other contributors to ballet turnout.

PubMed

Quanbeck, Amy E; Russell, Jeffrey A; Handley, Sara C; Quanbeck, Deborah S

2017-02-01

Turnout, or external rotation (ER) of the lower extremities, is essential in ballet. The purpose of this study was to utilise physical examination and a biomechanical method for obtaining functional kinematic data using hip and knee joint centres to identify the relative turnout contributions from hip rotation, femoral anteversion, knee rotation, tibial torsion, and other sources. Ten female dancers received a lower extremity alignment assessment, including passive hip rotation, femoral anteversion, tibial torsion, weightbearing foot alignment, and Beighton hypermobility score. Next, turnout was assessed using plantar pressure plots and three-dimensional motion analysis; participants performed turnout to ballet first position on both a plantar pressure mat and friction-reducing discs. A retro-reflective functional marker motion capture system mapped the lower extremities and hip and knee joint centres. Mean total turnout was 129±15.7° via plantar pressure plots and 135±17.8° via kinematics. Bilateral hip ER during turnout was 49±10.2° (36% of total turnout). Bilateral knee ER during turnout was 41±5.9° (32% of total turnout). Hip ER contribution to total turnout measured kinematically was less than expected compared to other studies, where hip ER was determined without functional kinematic data. Knee ER contributed substantially more turnout than expected or previously reported. This analysis method allows precise assessment of turnout contributors.

Intercomparison of Total Atmospheric Precipitable Water Vapor Retrieval Products during the 2009 and 2010 CAPABLE Summer Intensives

NASA Astrophysics Data System (ADS)

Pippin, M. R.; Knepp, T. N.; Bedka, S.; Cowen, L.; Murray, J.; Deslover, D.; Feltz, W.; Yesalusky, M. A.; Smith, W.; Cede, A.; Abuhassan, N.; Herman, J. R.; Szykamn, J.

2011-12-01

In support of NASA's GEO-CAPE mission and Air Quality Applied Sciences, the Chemistry and Physics Atmospheric Boundary Layer Experiment (CAPABLE) site at NASA Langley Research Center has been established in coordination with Environmental Protection Agency (EPA) and Virginia Department of Environmental Quality (VA DEQ) to assess the relationship between high temporal resolution measurements from space and continuous in situ surface observations. During the 2009 and 2010 CAPABLE summer intensives, three methods for determining total atmospheric precipitable water vapor were utilized. Continuous total column measurements of water vapor were provided using a Pandora spectrometer, the DOE/NSTec Atmospheric Sounder Spectrometer for Infrared Spectral Technology (ASSIST) operated by the Hampton University and the University of Wisconsin Atmospheric Emitted Radiance Interferometer (AERI). Continuous meteorological parameters were measured on a 5m tower and rawinsondes were launched intermittently throughout both measurement periods. We present preliminary results of the intercomparison of total precipitable water vapor from the three instrumental methods and compare with estimated values from dew point temperature and satellite overpass data. Results from this study will have applications to satellite validation and Pandora retrieval algorithm development. Disclaimer: Although this work was reviewed by the U.S. Environmental Protection Agency and National Aeronautics and Space Administration, and approved for publication, it may not necessarily reflect official Agency policy.

Use of geographic information management systems (GIMS) for nitrogen management

NASA Astrophysics Data System (ADS)

Diker, Kenan

1998-11-01

Geographic Information Management Systems (GIMS) was investigated in this study to develop an efficient nitrogen management scheme for corn. The study was conducted on two experimental corn sites. The first site consisted of six non-replicated plots where the canopy reflectance of corn at six nitrogen fertilizer levels was investigated. The reflectance measurements were conducted for nadir and 75sp° view angles. Data from these plots were used to develop relationships between reflectance data and soil and plant parameters. The second site had four corn plots fertilized by different methods such as spoon-fed, pre-plant and side-dress, which created nitrogen variability within the field. Soil and plant nitrogen as well as leaf area, biomass, percent cover measurements, and canopy reflectance data were collected at various growth stages from both sites during the 1995 and 1996 growing seasons. Relationships were developed between the Nitrogen Reflectance Index (NRI) developed by Bausch et al. (1994) and soil and plant variables. Spatial dependence of data was determined by geostatistical methods; variability was mapped in ArcView. Results of this study indicated that the NRI is a better estimator of plant nitrogen status than chlorophyll meter measurements. The NRI can successfully be used to estimate the spatial distribution of soil nitrogen estimates through the plant nitrogen status as well as plant parameters and the yield potential. GIS mapping of measured and estimated soil nitrogen agreed except in locations where hot spots were measured. The NRI value of 0.95 seemed to be the critical value for plant nitrogen status especially for the 75sp° view. The nadir view tended to underestimate plant and soil parameters, whereas, the 75sp° view slightly overestimated these parameters. If available, the 75sp° view data should be used before the tasseling stage for reflectance measurements to reduce the soil background effect. However, it is sensitive to windy conditions. After tasseling, the nadir view should be used because the 75sp° view is obstructed by tassels. Total soil nitrogen at the V6 growth stage was underestimated by the NRI for both view angles. Results also indicated that a nitrogen prescription could be estimated at various growth stages.

[Effects of plateau zokor disturbance and restoration years on soil nutrients and microbial functional diversity in alpine meadow].

PubMed

Hu, Lei; Ade, Lu-ji; Zi, Hong-biao; Wang, Chang-ting

2015-09-01

To explore the dynamic process of restoration succession in degraded alpine meadow that had been disturbed by plateau zokors in the eastern Tibetan Plateau, we examined soil nutrients and microbial functional diversity using conventional laboratory analysis and the Biolog-ECO microplate method. Our study showed that: 1) The zokors disturbance significantly reduced soil organic matter, total nitrogen, available nitrogen and phosphorus contents, but had no significant effects on soil total phosphorus and potassium contents; 2) Soil microbial carbon utilization efficiency, values of Shannon, Pielou and McIntosh indexes increased with alpine meadow restoration years; 3) Principal component analysis (PCA) showed that carbohydrates and amino acids were the main carbon sources for maintaining soil microbial community; 4) Redundancy analysis ( RDA) indicated that soil pH, soil organic matter, total nitrogen, available nitrogen, and total potassium were the main factors influencing the metabolic rate of soil microbial community and microbial functional diversity. In summary, variations in soil microbial functional diversity at different recovery stages reflected the microbial response to aboveground vegetation, soil microbial composition and soil nutrients.

Diagnostics of normal and cancer tissues by fiberoptic evanescent wave Fourier transform IR (FEW-FTIR) spectroscopy

NASA Astrophysics Data System (ADS)

Afanasyeva, Natalia I.

1998-06-01

Fourier Transform Infrared (FTIR) Spectroscopy using optical fibers operated in the attenuated total reflection (ATR) regime in the mid-IR region in the range 850 to 4000 cm-1 has recently found an application in the noninvasive diagnostics of tissues in vivo. The method is suitable for nondestructive, nontoxic, fast (seconds), direct measurements of the spectra of normal and pathological tissues in vitro, ex vivo, and in vivo in real time. The aim of our studies is the express testing of various tumor tissues at the early stages of their development. The method is expected to be further developed for endoscopic and biopsy applications as well as for the research of different materials.

A cell-free assay to determine the stoichiometry of plasma membrane proteins.

PubMed

Trigo, Cesar; Vivar, Juan P; Gonzalez, Carlos B; Brauchi, Sebastian

2013-04-01

Plasma membrane receptors, transporters, and ion channel molecules are often found as oligomeric structures that participate in signaling cascades essential for cell survival. Different states of protein oligomerization may play a role in functional control and allosteric regulation. Stochastic GFP-photobleaching (SGP) has emerged as an affordable and simple method to determine the stoichiometry of proteins at the plasma membrane. This non-invasive optical approach can be useful for total internal reflection of fluorescence microscopy (TIRFM), where signal-to-noise ratio is very high at the plasma membrane. Here, we report an alternative methodology implemented on a standard laser scanning confocal microscope (LSCM). The simplicity of our method will allow for its implementation in any epifluorescence microscope of choice.

Characterization of perovskite film prepared by pulsed laser deposition on ferritic stainless steel using microscopic and optical methods

NASA Astrophysics Data System (ADS)

Durda, E.; Jaglarz, J.; Kąc, S.; Przybylski, K.; El Kouari, Y.

2016-06-01

The perovskite La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF48) film was deposited on Crofer 22 APU ferritic stainless steel by pulsed laser deposition (PLD). Morphological studies of the sample were performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Information about film thickness and surface topography of the film and the steel substrate were obtained using following optical methods: spectroscopic ellipsometry (SE), bidirectional reflection distribution function (BRDF) and total integrated reflectometry (TIS). In particular, the BRDF study, being complementary to atomic force microscopy, yielded information about surface topography. Using the previously mentioned methods, the following statistic surface parameters were determined: root-mean square (rms) roughness and autocorrelation length by determining the power spectral density (PSD) function of surface irregularities.

Potential of near infrared spectroscopy for the analysis of mycotoxins applied to naturally contaminated red paprika found in the Spanish market.

PubMed

Hernández-Hierro, J M; García-Villanova, R J; González-Martín, I

2008-08-01

The potential of the near infrared spectroscopy (NIRS) technique for the analysis of red paprika for aflatoxin B(1), ochratoxin A and total aflatoxins is explored. As a reference, the results from a chromatographic method with fluorescence detection (HPLC-FD) following an immunoaffinity cleanup (IAC) were employed. For the NIRS measurement, a remote reflectance fibre-optic probe was applied directly onto the samples of paprika. There was no need for pre-treatment or manipulation of the sample. The modified partial least squares (MPLS) algorithm was employed as a regression method. The multiple correlation coefficients (RSQ) and the prediction corrected standard errors (SEP(C)) were respectively 0.955 and 0.2 microg kg(-1), 0.853 and 2.3 microg kg(-1), 0.938 and 0.3 microg kg(-1) for aflatoxin B(1), ochratoxin A and total aflatoxins, respectively. The capacity for prediction of the developed model measured as ratio performance deviation (RPD) for aflatoxin B(1) (5.2), ochratoxin A (2.8) and total aflatoxins (4.4) indicate that NIRS technique using a fibre-optic probe offers an alternative for the determination of these three parameters in paprika, with an advantageously lower cost and higher speed as compared with the chemical method. Content of aflatoxin B(1) and total aflatoxins are the parameters currently employed by the food regulations to limit the levels of the four aflatoxins in many foodstuffs. In addition, aflatoxin B(1) itself is an excellent indicator for aflatoxins' contamination since it is always the most abundant and toxic.

Research on the method of establishing the total radiation meter calibration device

NASA Astrophysics Data System (ADS)

Gao, Jianqiang; Xia, Ming; Xia, Junwen; Zhang, Dong

2015-10-01

Pyranometer is an instrument used to measure the solar radiation, according to pyranometer differs as installation state, can be respectively measured total solar radiation, reflected radiation, or with the help of shading device for measuring scattering radiation. Pyranometer uses the principle of thermoelectric effect, inductive element adopts winding plating type multi junction thermopile, its surface is coated with black coating with high absorption rate. Hot junction in the induction surface, while the cold junction is located in the body, the cold and hot junction produce thermoelectric potential. In the linear range, the output signal is proportional to the solar irradiance. Traceability to national meteorological station, as the unit of the national legal metrology organizations, the responsibility is to transfer value of the sun and the earth radiation value about the national meteorological industry. Using the method of comparison, with indoor calibration of solar simulator, at the same location, standard pyranometer and measured pyranometer were alternately measured radiation irradiance, depending on the irradiation sensitivity standard pyranometer were calculated the radiation sensitivity of measured pyranometer. This paper is mainly about the design and calibration method of the pyranometer indoor device. The uncertainty of the calibration result is also evaluated.

Scintillator reflective layer coextrusion

DOEpatents

Yun, Jae-Chul; Para, Adam

2001-01-01

A polymeric scintillator has a reflective layer adhered to the exterior surface thereof. The reflective layer comprises a reflective pigment and an adhesive binder. The adhesive binder includes polymeric material from which the scintillator is formed. A method of forming the polymeric scintillator having a reflective layer adhered to the exterior surface thereof is also provided. The method includes the steps of (a) extruding an inner core member from a first amount of polymeric scintillator material, and (b) coextruding an outer reflective layer on the exterior surface of the inner core member. The outer reflective layer comprises a reflective pigment and a second amount of the polymeric scintillator material.

Determination of element levels in human serum: Total reflection X-ray fluorescence applications

NASA Astrophysics Data System (ADS)

Majewska, U.; Łyżwa, P.; Łyżwa, K.; Banaś, D.; Kubala-Kukuś, A.; Wudarczyk-Moćko, J.; Stabrawa, I.; Braziewicz, J.; Pajek, M.; Antczak, G.; Borkowska, B.; Góźdź, S.

2016-08-01

Deficiency or excess of elements could disrupt proper functioning of the human body and could lead to several disorders. Determination of their concentrations in different biological human fluids and tissues should become a routine practice in medical treatment. Therefore the knowledge about appropriate element concentrations in human organism is required. The purpose of this study was to determine the concentration of several elements (P, S, Cl, K, Ca, Cr, Fe, Cu, Zn, Se, Br, Rb, Pb) in human serum and to define the reference values of element concentration. Samples of serum were obtained from 105 normal presumably healthy volunteers (66 women aged between 15 and 78 years old; 39 men aged between 15 and 77 years old). Analysis has been done for the whole studied population and for subgroups by sex and age. It is probably first so a wide study of elemental composition of serum performed in the case of Świętokrzyskie region. Total reflection X-ray fluorescence (TXRF) method was used to perform the elemental analysis. Spectrometer S2 Picofox (Bruker AXS Microanalysis GmbH) was used to identify and measure elemental composition of serum samples. Finally, 1st and 3rd quartiles were accepted as minimum and maximum values of concentration reference range.

Total reflection X-ray fluorescence as a tool for food screening

NASA Astrophysics Data System (ADS)

Borgese, Laura; Bilo, Fabjola; Dalipi, Rogerta; Bontempi, Elza; Depero, Laura E.

2015-11-01

This review provides a comprehensive overview of the applications of total reflection X-ray fluorescence (TXRF) in the field of food analysis. Elemental composition of food is of great importance, since food is the main source of essential, major and trace elements for animals and humans. Some potentially toxic elements, dangerous for human health may contaminate food, entering the food chain from the environment, processing, and storage. For this reason the elemental analysis of food is fundamental for safety assessment. Fast and sensitive analytical techniques, able to detect major and trace elements, are required as a result of the increasing demand on multi-elemental information and product screening. TXRF is suitable for elemental analysis of food, since it provides simultaneous multi-elemental identification in a wide dynamic range of concentrations. Several different matrices may be analyzed obtaining results with a good precision and accuracy. In this review, the most recent literature about the use of TXRF for the analysis of food is reported. The focus is placed on the applications within food quality monitoring of drinks, beverages, vegetables, fruits, cereals, animal derivatives and dietary supplements. Furthermore, this paper provides a critical outlook on the developments required to transfer these methods from research to the industrial and analytical laboratories contexts.

Mineral elements and essential trace elements in blood of seals of the North Sea measured by total-reflection X-ray fluorescence analysis

NASA Astrophysics Data System (ADS)

Griesel, S.; Mundry, R.; Kakuschke, A.; Fonfara, S.; Siebert, U.; Prange, A.

2006-11-01

Mineral and essential trace elements are involved in numerous physiological processes in mammals. Often, diseases are associated with an imbalance of the electrolyte homeostasis. In this study, the concentrations of mineral elements (P, S, K, Ca) and essential trace elements (Fe, Cu, Zn, Se, Rb, Sr) in whole blood of harbor seals ( Phoca vitulina) were determined using total-reflection X-ray fluorescence spectrometry (TXRF). Samples from 81 free-ranging harbor seals from the North Sea and two captive seals were collected during 2003-2005. Reference ranges and element correlations for health status determination were derived for P, S, K, Ca, Fe, Cu, and Zn level in whole blood. Grouping the seals by age, gender and sample location the concentration levels of the elements were compared. The blood from two captive seals with signs of diseases and four free-ranging seals showed reduced element levels of P, S, and Ca and differences in element correlation of electrolytes were ascertained. Thus, simultaneous measurements of several elements in only 500 μL volumes of whole blood provide the possibility to obtain information on both, the electrolyte balance and the hydration status of the seals. The method could therefore serve as an additional biomonitoring tool for the health assessment.

Preparation of a New Oligolamellar Stratum Corneum Lipid Model.

PubMed

Mueller, Josefin; Schroeter, Annett; Steitz, Roland; Trapp, Marcus; Neubert, Reinhard H H

2016-05-10

In this study, we present a preparation method for a new stratum corneum (SC) model system, which is closer to natural SC than the commonly used multilayer models. The complex setup of the native SC lipid matrix was mimicked by a ternary lipid mixture of ceramide [AP], cholesterol, and stearic acid. A spin coating procedure was applied to realize oligo-layered samples. The influence of lipid concentration, rotation speed, polyethylenimine, methanol content, cholesterol fraction, and annealing on the molecular arrangement of the new SC model was investigated by X-ray reflectivity measurements. The new oligo-SC model is closer to native SC in the total number of lipid membranes found between corneocytes. The reduction in thickness provides the opportunity to study the effects of drugs and/or hydrophilic penetration enhancers on the structure of SC in full detail by X-ray or neutron reflectivity. In addition, the oligo-lamellar systems allows one to infer not only the lamellar spacing, but also the total thickness of the oligo-SC model and changes thereof can be monitored. This improvement is most helpful for the understanding of transdermal drug administration on the nanoscale. The results are compared to the commonly used multilamellar lipid model systems and advantages and disadvantages of both models are discussed.

Metacognitive abilities in adults with substance abuse treated in therapeutic community.

PubMed

Inchausti, Felix; Ortuño-Sierra, Javier; García-Poveda, Nancy V; Ballesteros-Prados, Alejandro

2016-09-29

The term metacognition reflects a spectrum of psychological activities that allows people to form and integrate representations about their own mental states and those of others. The main goal of this study was to examine whether people with substance abuse disorders (SUDs), and treated in therapeutic community regime, displayed specific patterns of metacognitive deficits on Self-reflectivity, Understanding others’ mind, Decentration, and Mastery, comparing their scores with two clinical groups of patients with schizophrenia spectrum disorders (SSDs) and anxiety disorders. A mixed-methods (qualitative-quantitative) study was designed. Two hundred and sixteen adults aged 18-65 with principal diagnoses of SUDs (n = 52), SSDs (n = 49), and anxiety disorders (n = 115) were recruited. Qualitative data were obtained with the Metacognition Assessment Interview, which was then rated using a quantitative scale, the Metacognition Assessment Scale-Abbreviated (MAS-A). The anxiety disorders group had significantly higher MAS-A total scores than the SUDs group, and the SUDs group obtained significantly higher MAS-A total scores than the SSDs group. Concerning the MAS-A subscale scores, the SUDs group displayed significantly lower scores only on the Mastery subscale compared to the anxiety disorders group, with the SUDs and SSDs groups obtaining equivalent Mastery scores. According to these findings, current interventions for addiction should focus more specifically on improving metacognitive Mastery.

k-Space Image Correlation Spectroscopy: A Method for Accurate Transport Measurements Independent of Fluorophore Photophysics

PubMed Central

Kolin, David L.; Ronis, David; Wiseman, Paul W.

2006-01-01

We present the theory and application of reciprocal space image correlation spectroscopy (kICS). This technique measures the number density, diffusion coefficient, and velocity of fluorescently labeled macromolecules in a cell membrane imaged on a confocal, two-photon, or total internal reflection fluorescence microscope. In contrast to r-space correlation techniques, we show kICS can recover accurate dynamics even in the presence of complex fluorophore photobleaching and/or “blinking”. Furthermore, these quantities can be calculated without nonlinear curve fitting, or any knowledge of the beam radius of the exciting laser. The number densities calculated by kICS are less sensitive to spatial inhomogeneity of the fluorophore distribution than densities measured using image correlation spectroscopy. We use simulations as a proof-of-principle to show that number densities and transport coefficients can be extracted using this technique. We present calibration measurements with fluorescent microspheres imaged on a confocal microscope, which recover Stokes-Einstein diffusion coefficients, and flow velocities that agree with single particle tracking measurements. We also show the application of kICS to measurements of the transport dynamics of α5-integrin/enhanced green fluorescent protein constructs in a transfected CHO cell imaged on a total internal reflection fluorescence microscope using charge-coupled device area detection. PMID:16861272

Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy as a Forensic Method to Determine the Composition of Inks Used to Print the United States One-cent Blue Benjamin Franklin Postage Stamps of the 19th Century.

PubMed

Brittain, Harry G

2016-01-01

Through the combined use of infrared (IR) absorption spectroscopy and attenuated total reflectance (ATR) sampling, the composition of inks used to print the many different types of one-cent Benjamin Franklin stamps of the 19th century has been established. This information permits a historical evaluation of the formulations used at various times, and also facilitates the differentiation of the various stamps from each other. In two instances, the ink composition permits the unambiguous identification of stamps whose appearance is identical, and which (until now) have only been differentiated through estimates of the degree of hardness or softness of the stamp paper, or through the presence or absence of a watermark in the paper. In these instances, the use of ATR Fourier transform infrared spectroscopy (FT-IR) spectroscopy effectively renders irrelevant two 100-year-old practices of stamp identification. Furthermore, since the use of ATR sampling makes it possible to obtain the spectrum of a stamp still attached to its cover, it is no longer necessary to identify these blue Franklin stamps using their cancellation dates. © The Author(s) 2015.

Total internal reflection holographic microscopy (TIRHM) for quantitative phase characterization of cell-substrate adhesion

NASA Astrophysics Data System (ADS)

Ash, William Mason, III

Total Internal Reflection Holographic Microscopy (TIRHM) combines near-field microscopy with digital holography to produce a new form of near-field phase microscopy. Using a prism in TIR as a near-field imager, the presence of microscopic organisms, cell-substrate interfaces, and adhesions, causes relative refractive index (RRI) and frustrated TIR (f-TIR) to modulate the object beam's evanescent wave phase front. Quantitative phase images of test specimens such as Amoeba proteus, Dictyostelium Discoideum and cells such as SKOV-3 ovarian cancer and 3T3 fibroblasts are produced without the need to introduce stains or fluorophores. The angular spectrum method of digital holography to compensate for tilt anamorphism due to the inclined TIR plane is also discussed. The results of this work conclusively demonstrate, for the first time, the integration of near-field microscopy with digital holography. The cellular images presented show a correlation between the physical extent of the Amoeba proteus plasma membrane and the adhesions that are quantitatively profiled by phase cross-sectioning of the holographic images obtained by digital holography. With its ability to quantitatively characterise cellular adhesion and motility, it is anticipated that TIRHM can be a tool for characterizing and combating cancer metastasis, as well as improving our understanding of morphogenesis and embryogenesis itself.

Realization of a near-perfect antireflection coating for silicon solar energy utilization.

PubMed

Kuo, Mei-Ling; Poxson, David J; Kim, Yong Sung; Mont, Frank W; Kim, Jong Kyu; Schubert, E Fred; Lin, Shawn-Yu

2008-11-01

To harness the full spectrum of solar energy, Fresnel reflection at the surface of a solar cell must be eliminated over the entire solar spectrum and at all angles. Here, we show that a multilayer nanostructure having a graded-index profile, as predicted by theory [J. Opt. Soc. Am. 66, 515 (1976); Appl. Opt. 46, 6533 (2007)], can accomplish a near-perfect transmission of all-color of sunlight. An ultralow total reflectance of 1%-6% has been achieved over a broad spectrum, lambda = 400 to 1600 nm, and a wide range of angles of incidence, theta = 0 degrees-60 degrees . The measured angle- and wavelength-averaged total reflectance of 3.79% is the smallest ever reported in the literature, to our knowledge.

Theoretical analysis of non-polarizing beam splitters with appropriate amplitude and phase

NASA Astrophysics Data System (ADS)

Shi, Jin Hui; Wang, Zheng Ping; Guan, Chun Ying

2009-04-01

When used at oblique angles of incidence, the reflectance and transmittance of thin films exhibit strong polarization effects, particularly for the films inside a glass cube. However, the polarization effects are undesirable in many applications. Novel non-polarizing beam splitter designs are shown. Non-polarizing beam splitters with unique optical thin films are achieved through the combination of interference and frustrated total internal reflection. The non-polarizing condition expressions based on frustrated total internal reflection are derived, and examples of the non-polarizing beam splitters are also presented with the optimization technique and the results of Rp=(50±0.5)%, Rs=(50±0.5)%, and Δr=(0±0.3) in the wavelength range of 400-700 nm are obtained.

Valuing the Economic Costs of Allergic Rhinitis, Acute Bronchitis, and Asthma from Exposure to Indoor Dampness and Mold in the US

PubMed Central

2016-01-01

Two foundational methods for estimating the total economic burden of disease are cost of illness (COI) and willingness to pay (WTP). WTP measures the full cost to society, but WTP estimates are difficult to compute and rarely available. COI methods are more often used but less likely to reflect full costs. This paper attempts to estimate the full economic cost (2014$) of illnesses resulting from exposure to dampness and mold using COI methods and WTP where the data is available. A limited sensitivity analysis of alternative methods and assumptions demonstrates a wide potential range of estimates. In the final estimates, the total annual cost to society attributable to dampness and mold is estimated to be $3.7 (2.3–4.7) billion for allergic rhinitis, $1.9 (1.1–2.3) billion for acute bronchitis, $15.1 (9.4–20.6) billion for asthma morbidity, and $1.7 (0.4–4.5) billion for asthma mortality. The corresponding costs from all causes, not limited to dampness and mold, using the same approach would be $24.8 billion for allergic rhinitis, $13.5 billion for acute bronchitis, $94.5 billion for asthma morbidity, and $10.8 billion for asthma mortality. PMID:27313630

Transmittance of transparent windows with non-absorbing cap-shaped droplets condensed on their backside

NASA Astrophysics Data System (ADS)

Zhu, Keyong; Huang, Yong; Pruvost, Jeremy; Legrand, Jack; Pilon, Laurent

2017-06-01

This study aims to quantify systematically the effect of non-absorbing cap-shaped droplets condensed on the backside of transparent windows on their directional-hemispherical transmittance and reflectance. Condensed water droplets have been blamed to reduce light transfer through windows in greenhouses, solar desalination plants, and photobioreactors. Here, the directional-hemispherical transmittance was predicted by Monte Carlo ray-tracing method. For the first time, both monodisperse and polydisperse droplets were considered, with contact angle between 0 and 180°, arranged either in an ordered hexagonal pattern or randomly distributed on the window backside with projected surface area coverage between 0 and 90%. The directional-hemispherical transmittance was found to be independent of the size and spatial distributions of the droplets. Instead, it depended on (i) the incident angle, (ii) the optical properties of the window and droplets, and on (iii) the droplet contact angle and (iv) projected surface area coverage. In fact, the directional-hemispherical transmittance decreased with increasing incident angle. Four optical regimes were identified in the normal-hemispherical transmittance. It was nearly constant for droplet contact angles either smaller than the critical angle θcr (predicted by Snell's law) for total internal reflection at the droplet/air interface or larger than 180°-θcr. However, between these critical contact angles, the normal-hemispherical transmittance decreased rapidly to reach a minimum at 90° and increased rapidly with increasing contact angles up to 180°-θcr. This was attributed to total internal reflection at the droplet/air interface which led to increasing reflectance. In addition, the normal-hemispherical transmittance increased slightly with increasing projected surface area coverage for contact angle was smaller than θcr. However, it decreased monotonously with increasing droplet projected surface area coverage for contact angle larger than θcr. These results can be used to select the material or surface coating with advantageous surface properties for applications when dropwise condensation may otherwise have a negative effect on light transmittance.

Five in a row—reactions of smokers to tobacco tax increases: population‐based cross‐sectional studies in Germany 2001–2006

PubMed Central

Hanewinkel, Reiner; Isensee, Barbara

2007-01-01

Objective To assess reactions of smokers to five waves of tobacco tax increases in Germany. Design A 10‐wave cross‐sectional study, with assessments before and after the tax increases. Setting General population of Germany. Participants and methods 10 representative samples from the general population with a total number of 27 608 people aged ⩾14 years, including 8548 smokers (31% of the total sample), were interviewed. Outcome measures Reflection on smoking behaviour, and smoking behaviour (quitting, reducing, switching to a cheaper brand or no change) before and after tobacco tax increases. Results Before the tax increases, one third to more than half of the smokers reflected on their smoking behaviour, 9.7–13.9% intended to quit, 23.4–34.7% intended to reduce smoking and 10.8–16.4% intended to switch to cheaper tobacco products, whereas 36.1–52.1% did not intend any change at all. After the tax increases, one fourth to more than one third reported to have reflected on their smoking behaviour, 4.0–7.9% quit smoking owing to the increase, 11.5–16.6% reduced consumption and 11.0–19.9% switched to cheaper products. Significant associations were found between the height of the price increase and the intentions and reactions of smokers. Conclusions Price increases lead to a substantial reflection on smoking and intended and realised behaviour changes such as reduced consumption and switching to cheaper tobacco products. These effects are more pronounced the more the price rises. Therefore, taxation policy will lead to quitting and reducing smoking. However, complementary measures should also be taken to prevent smokers switching to cheaper tobacco products, which would reduce the effectiveness of taxation policy. PMID:17297071

Whole body protein kinetics measured with a non-invasive method in severely burned children

PubMed Central

Børsheim, Elisabet; Chinkes, David L.; McEntire, Serina J.; Rodriguez, Nancy R.; Herndon, David N.; Suman, Oscar E.

2010-01-01

Persistent and extensive skeletal muscle catabolism is characteristic of severe burns. Whole body protein metabolism, an important component of this process, has not been measured in burned children during the long-term convalescent period. The aim of this study was to measure whole body protein turnover in burned children at discharge (95% healed) and in healthy controls by a non-invasive stable isotope method. Nine burned children (7 boys, 2 girls; 54 ± 14 (SD)% total body area burned; 13 ± 4 yrs; 45 ± 20 kg; 154 ± 14 cm) and 12 healthy children (8 boys, 4 girls; 12 ± 3 yrs; 54 ± 16 kg;150 ± 22 cm) were studied. A single oral dose of 15N-alanine (16 mg/kg) was given, and thereafter urine was collected for 34 hours. Whole body protein flux was calculated from labeling of urinary urea nitrogen. Then, protein synthesis was calculated as protein flux minus excretion, and protein breakdown as flux minus intake. At discharge, total protein turnover was 4.53 ± 0.65 (SE) g kg bodyweight−1 day−1 in the burned children compared to 3.20 ± 0.22 g kg−1 day−1 in controls (P = 0.02). Expressed relative to lean body mass (LBM), the rates were 6.12 ± 0.94 vs. 4.60 ± 0.36 g kg LBM−1 day−1 in burn vs. healthy (P = 0.06). Total protein synthesis was also elevated in burned vs. healthy children, and a tendency for elevated protein breakdown was observed. Conclusion: Total protein turnover is elevated in burned children at discharge compared to age-matched controls, possibly reflecting the continued stress response to severe burn. The oral 15N-alanine bolus method is a convenient, non-invasive, and no-risk method for measurement of total body protein turnover. PMID:20392565

Determining moisture content in pasta by vibrational spectroscopy.

PubMed

Czaja, Tomasz; Kuzawińska, Ewelina; Sobota, Aldona; Szostak, Roman

2018-02-01

Pasta aside from bread is the most consumed cereal-based product in the world. Its taste and cooking ease makes it the basis of many cuisines. The pasta dough formed by mixing flour and water is extruded through an extrusion die to mould the appropriate pasta form and is dried to obtain a stable product. The concentration of moisture in the pasta dough is a one of key parameters determining the final quality of the product. Monitoring the moisture content of pasta after extrusion is also critically important. It enables a selection of suitable drying conditions that ensure the appropriate parameters of pasta, such as texture, color and taste, are met. A method for the quantitative determination of moisture content in pasta dough and in pasta based on the partial least squares treatment of infrared spectra registered using a single-reflection attenuated total reflectance diamond accessory is described. Results of a similar quality were found using models derived from near infrared spectra obtained in a diffuse reflectance mode and slightly worse based on Raman spectra. Relative standard errors of prediction calculated for moisture quantification by ATR/NIR/Raman techniques amounted to 2.54/3.16/5.56% and 2.15/3.32/5.67%, for calibration and validation sets, respectively. The proposed procedures can be used for fast and efficient pasta moisture quantification and may replace the current, more laborious methods used. Copyright © 2017 Elsevier B.V. All rights reserved.

Reverse total shoulder arthroplasty: research models

PubMed Central

PETRILLO, STEFANO; LONGO, UMILE GIUSEPPE; GULOTTA, LAWRENCE V.; BERTON, ALESSANDRA; KONTAXIS, ANDREAS; WRIGHT, TIMOTHY; DENARO, VINCENZO

2016-01-01

Purpose the past decade has seen a considerable increase in the use of research models to study reverse total shoulder arthroplasty (RTSA). Nevertheless, none of these models has been shown to completely reflect real in vivo conditions. Methods we performed a systematic review of the literature matching the following key words: “reverse total shoulder arthroplasty” or “reverse total shoulder replacement” or “reverse total shoulder prosthesis” and “research models” or “biomechanical models” or “physical simulators” or “virtual simulators”. The following databases were screened: Medline, Google Scholar, EMBASE, CINAHIL and Ovid. We identified and included all articles reporting research models of any kind, such as physical or virtual simulators, in which RTSA and the glenohumeral joint were reproduced. Results computer models and cadaveric models are the most commonly used, and they were shown to be reliable in simulating in vivo conditions. Bone substitute models have been used in a few studies. Mechanical testing machines provided useful information on stability factors in RTSA. Conclusion because of the limitations of each individual model, additional research is required to develop a research model of RTSA that may reduce the limitations of those presently available, and increase the reproducibility of this technique in the clinical setting. PMID:28217660

Optimal Atmospheric Correction for Above-Ground Forest Biomass Estimation with the ETM+ Remote Sensor.

PubMed

Nguyen, Hieu Cong; Jung, Jaehoon; Lee, Jungbin; Choi, Sung-Uk; Hong, Suk-Young; Heo, Joon

2015-07-31

The reflectance of the Earth's surface is significantly influenced by atmospheric conditions such as water vapor content and aerosols. Particularly, the absorption and scattering effects become stronger when the target features are non-bright objects, such as in aqueous or vegetated areas. For any remote-sensing approach, atmospheric correction is thus required to minimize those effects and to convert digital number (DN) values to surface reflectance. The main aim of this study was to test the three most popular atmospheric correction models, namely (1) Dark Object Subtraction (DOS); (2) Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) and (3) the Second Simulation of Satellite Signal in the Solar Spectrum (6S) and compare them with Top of Atmospheric (TOA) reflectance. By using the k-Nearest Neighbor (kNN) algorithm, a series of experiments were conducted for above-ground forest biomass (AGB) estimations of the Gongju and Sejong region of South Korea, in order to check the effectiveness of atmospheric correction methods for Landsat ETM+. Overall, in the forest biomass estimation, the 6S model showed the bestRMSE's, followed by FLAASH, DOS and TOA. In addition, a significant improvement of RMSE by 6S was found with images when the study site had higher total water vapor and temperature levels. Moreover, we also tested the sensitivity of the atmospheric correction methods to each of the Landsat ETM+ bands. The results confirmed that 6S dominates the other methods, especially in the infrared wavelengths covering the pivotal bands for forest applications. Finally, we suggest that the 6S model, integrating water vapor and aerosol optical depth derived from MODIS products, is better suited for AGB estimation based on optical remote-sensing data, especially when using satellite images acquired in the summer during full canopy development.

Rapid and quantitative detection of the microbial spoilage in chicken meat by diffuse reflectance spectroscopy (600-1100 nm).

PubMed

Lin, M; Al-Holy, M; Mousavi-Hesary, M; Al-Qadiri, H; Cavinato, A G; Rasco, B A

2004-01-01

To evaluate the feasibility of visible and short-wavelength near-infrared (SW-NIR) diffuse reflectance spectroscopy (600-1100 nm) to quantify the microbial loads in chicken meat and to develop a rapid methodology for monitoring the onset of spoilage. Twenty-four prepackaged fresh chicken breast muscle samples were prepared and stored at 21 degrees C for 24 h. Visible and SW-NIR was used to detect and quantify the microbial loads in chicken breast muscle at time intervals of 0, 2, 4, 6, 8, 10, 12 and 24 h. Spectra were collected in the diffuse reflectance mode (600-1100 nm). Total aerobic plate count (APC) of each sample was determined by the spread plate method at 32 degrees C for 48 h. Principal component analysis (PCA) and partial least squares (PLS) based prediction models were developed. PCA analysis showed clear segregation of samples held 8 h or longer compared with 0-h control. An optimum PLS model required eight latent variables for chicken muscle (R = 0.91, SEP = 0.48 log CFU g(-1)). Visible and SW-NIR combined with PCA is capable of perceiving the change of the microbial loads in chicken muscle once the APC increases slightly above 1 log cycle. Accurate quantification of the bacterial loads in chicken muscle can be calculated from the PLS-based prediction method. Visible and SW-NIR spectroscopy is a technique with a considerable potential for monitoring food safety and food spoilage. Visible and SW-NIR can acquire a metabolic snapshot and quantify the microbial loads of food samples rapidly, accurately, and noninvasively. This method would allow for more expeditious applications of quality control in food industries.

Structural characterization of the phospholipid stabilizer layer at the solid-liquid interface of dispersed triglyceride nanocrystals with small-angle x-ray and neutron scattering

NASA Astrophysics Data System (ADS)

Schmiele, Martin; Schindler, Torben; Unruh, Tobias; Busch, Sebastian; Morhenn, Humphrey; Westermann, Martin; Steiniger, Frank; Radulescu, Aurel; Lindner, Peter; Schweins, Ralf; Boesecke, Peter

2013-06-01

Dispersions of crystalline nanoparticles with at least one sufficiently large unit cell dimension can give rise to Bragg reflections in the small-angle scattering range. If the nanocrystals possess only a small number of unit cells along these particular crystallographic directions, the corresponding Bragg reflections will be broadened. In a previous study of phospholipid stabilized dispersions of β-tripalmitin platelets [Unruh, J. Appl. Crystallogr.JACGAR0021-889810.1107/S0021889807044378 40, 1008 (2007)], the x-ray powder pattern simulation analysis (XPPSA) was developed. The XPPSA method facilitates the interpretation of the rather complicated small-angle x-ray scattering (SAXS) curves of such dispersions of nanocrystals. The XPPSA method yields the distribution function of the platelet thicknesses and facilitates a structural characterization of the phospholipid stabilizer layer at the solid-liquid interface between the nanocrystals and the dispersion medium from the shape of the broadened 001 Bragg reflection. In this contribution an improved and extended version of the XPPSA method is presented. The SAXS and small-angle neutron scattering patterns of dilute phospholipid stabilized tripalmitin dispersions can be reproduced on the basis of a consistent simulation model for the particles and their phospholipid stabilizer layer on an absolute scale. The results indicate a surprisingly flat arrangement of the phospholipid molecules in the stabilizer layer with a total thickness of only 12 Å. The stabilizer layer can be modeled by an inner shell for the fatty acid chains and an outer shell including the head groups and additional water. The experiments support a dense packing of the phospholipid molecules on the nanocrystal surfaces rather than isolated phospholipid domains.

Effects of Sample Preparation on the Infrared Reflectance Spectra of Powders

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

Brauer, Carolyn S.; Johnson, Timothy J.; Myers, Tanya L.

2015-05-22

While reflectance spectroscopy is a useful tool in identifying molecular compounds, laboratory measurement of solid (particularly powder) samples often is confounded by sample preparation methods. For example, both the packing density and surface roughness can have an effect on the quantitative reflectance spectra of powdered samples. Recent efforts in our group have focused on developing standard methods for measuring reflectance spectra that accounts for sample preparation, as well as other factors such as particle size and provenance. In this work, the effect of preparation method on sample reflectivity was investigated by measuring the directional-hemispherical spectra of samples that were hand-packedmore » as well as pressed into pellets using an integrating sphere attached to a Fourier transform infrared spectrometer. The results show that the methods used to prepare the sample have a substantial effect on the measured reflectance spectra, as do other factors such as particle size.« less

Effects of sample preparation on the infrared reflectance spectra of powders

NASA Astrophysics Data System (ADS)

Brauer, Carolyn S.; Johnson, Timothy J.; Myers, Tanya L.; Su, Yin-Fong; Blake, Thomas A.; Forland, Brenda M.

2015-05-01

While reflectance spectroscopy is a useful tool for identifying molecular compounds, laboratory measurement of solid (particularly powder) samples often is confounded by sample preparation methods. For example, both the packing density and surface roughness can have an effect on the quantitative reflectance spectra of powdered samples. Recent efforts in our group have focused on developing standard methods for measuring reflectance spectra that accounts for sample preparation, as well as other factors such as particle size and provenance. In this work, the effect of preparation method on sample reflectivity was investigated by measuring the directional-hemispherical spectra of samples that were hand-loaded as well as pressed into pellets using an integrating sphere attached to a Fourier transform infrared spectrometer. The results show that the methods used to prepare the sample can have a substantial effect on the measured reflectance spectra, as do other factors such as particle size.

Influence of cultivar and fertilizer approach on curly kale (Brassica oleracea L. var. sabellica). 1. Genetic diversity reflected in agronomic characteristics and phytochemical concentration.

PubMed

Groenbaek, Marie; Jensen, Sidsel; Neugart, Susanne; Schreiner, Monika; Kidmose, Ulla; Kristensen, Hanne Lakkenborg

2014-11-26

The objectives were to investigate if genetic diversity among field-grown traditional and F1 hybrid kale cultivars was reflected in different agronomic characteristics and consequently glucosinolate (GLS) and flavonoid glycoside concentration. This study evaluated how nitrogen and sulfur supply and biomass allocation modified phytochemicals in two experiments with combinations of three cultivars and four N and two S application levels. Results showed less growth, and higher N concentration in the traditional cultivar 'Tiara' was associated with increased indole and total GLSs compared to traditional 'Høj Amager Toftø' and F1 hybrid 'Reflex' cultivars, which exhibited higher yield, lower N concentration, and different biomass allocation. S application increased total GLS concentration, whereas aliphatic GLS percentage decreased when N application increased. Decrease of six 'Reflex' GLSs besides quercetin glycosides and total flavonoid glycosides with increased N indicated higher N responsiveness for 'Reflex'. In conclusion, differences in agronomic characteristics were reflected in diverse phytochemical composition.

A review of remote sensing and grasslands literature

NASA Technical Reports Server (NTRS)

Tappan, G.; Kinsler, M. C. (Principal Investigator)

1982-01-01

Studies between 1971 and 1980 dealing with remote sensing of rangelands/grasslands in the multispectral band are summarized and evaluated. Vegetation and soil reflectance properties are described. In the majority of the studies, the effect of the reflectance of green rangelands vegetation on the reflectance from the total scene is the primary concern. Developments in technique are summarized and recommendations for further research are presented.

A one-shot-projection method for measurement of specular surfaces.

PubMed

Wang, Zhenzhou

2015-02-09

In this paper, a method is proposed to measure the shapes of specular surfaces with one-shot-projection of structured laser patterns. By intercepting the reflection of the reflected laser pattern twice with two diffusive planes, the closed form solution is achieved for each reflected ray. The points on the specular surface are reconstructed by computing the intersections of the incident rays and the reflected rays. The proposed method can measure both static and dynamic specular shapes due to its one-shot-projection, which is beyond the capability of most of state of art methods that need multiple projections. To our knowledge, the proposed method is the only method so far that could yield the closed form solutions for the dynamic and specular surfaces.

Analysis of Ni-HYDRIDE Thin Film after Surface Plasmon Generation by Laser Technique

NASA Astrophysics Data System (ADS)

Violante, V.; Castagna, E.; Sibilia, C.; Paoloni, S.; Sarto, F.

2005-12-01

A nickel hydride thin film was studied by the attenuated total reflection method. The differences in behavior between a "black" film, and a pure nickel film "blank," are shown. The black nickel hydride film has been obtained by a short electrolysis with 1 M Li2SO4 electrolyte in light water, A shift in the minimum of the observed reflected light occurs, together with a change in the minimum shape (i.e. its half-height width increases). These two phenomenon are due to the change in the electronic band structure of the metal induced by electrons added to the lattice by hydrogen. The change of the electronic structure, revealed by the laser coupling conditions, leads us to consider that a hydride phase was created. Both the blank (not hydrogenated) and black (hydrogenated) specimens were taken under He-Ne laser beam at the reflectance minimum angle for about three hours. A SIMS analysis was also implemented to reveal differences in the isotopic composition of Cu, as marker element between the blank and black films, in order to study the coupled effect of electrolysis and plasmon-polariton excitation on LENR processes in condensed matter.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Selective reflection of obliquely incident polarised light

NASA Astrophysics Data System (ADS)

Fofanov, Ya A.

2009-06-01

A series of reflection resonances formed by the hyperfine components of the D2-lines in the spectrum of the natural mixture of rubidium isotopes is studied. Passages from resonantly frustrated total internal reflection to resonance Brewster reflection caused by the frequency tuning of the incident light are demonstrated experimentally. The contrast of the strongest refection resonances exceeds 500% at the moderate heating of reflecting cells. The intensity of the reflected light changes in this case by more than 20 times. A theory is developed which is based on a two-level model for resonance atoms and Fresnel formulas for reflection coefficients. Numerical calculations based on the proposed theory confirm main experimental results.

Two-Dimensional Standing Wave Total Internal Reflection Fluorescence Microscopy: Superresolution Imaging of Single Molecular and Biological Specimens

PubMed Central

Chung, Euiheon; Kim, Daekeun; Cui, Yan; Kim, Yang-Hyo; So, Peter T. C.

2007-01-01

The development of high resolution, high speed imaging techniques allows the study of dynamical processes in biological systems. Lateral resolution improvement of up to a factor of 2 has been achieved using structured illumination. In a total internal reflection fluorescence microscope, an evanescence excitation field is formed as light is total internally reflected at an interface between a high and a low index medium. The <100 nm penetration depth of evanescence field ensures a thin excitation region resulting in low background fluorescence. We present even higher resolution wide-field biological imaging by use of standing wave total internal reflection fluorescence (SW-TIRF). Evanescent standing wave (SW) illumination is used to generate a sinusoidal high spatial frequency fringe pattern on specimen for lateral resolution enhancement. To prevent thermal drift of the SW, novel detection and estimation of the SW phase with real-time feedback control is devised for the stabilization and control of the fringe phase. SW-TIRF is a wide-field superresolution technique with resolution better than a fifth of emission wavelength or ∼100 nm lateral resolution. We demonstrate the performance of the SW-TIRF microscopy using one- and two-directional SW illumination with a biological sample of cellular actin cytoskeleton of mouse fibroblast cells as well as single semiconductor nanocrystal molecules. The results confirm the superior resolution of SW-TIRF in addition to the merit of a high signal/background ratio from TIRF microscopy. PMID:17483188

Chlorophyll Fluorescence Emissions of Vegetation Canopies From High Resolution Field Reflectance Spectra

NASA Technical Reports Server (NTRS)

Middleton, E. M.; Corp, L. A.; Daughtry, C. S. T.; Campbell, P. K. Entcheva

2006-01-01

A two-year experiment was performed on corn (Zea mays L.) crops under nitrogen (N) fertilization regimes to examine the use of hyperspectral canopy reflectance information for estimating chlorophyll fluorescence (ChlF) and vegetation production. Fluorescence of foliage in the laboratory has proven more rigorous than reflectance for correlation to plant physiology. Especially useful are emissions produced from two stable red and far-red chlorophyll ChlF peaks centered at 685V10 nm and 735V5 nm. Methods have been developed elsewhere to extract steady state solar induced fluorescence (SF) from apparent reflectance of vegetation canopies/landscapes using the Fraunhofer Line Depth (FLD) principal. Our study utilized these methods in conjunction with field-acquired high spectral resolution canopy reflectance spectra obtained in 2004 and 2005 over corn crops, as part of an ongoing multi-year experiment at the USDA/Agriculture Research Service in Beltsville, MD. A spectroradiometer (ASD-FR Fieldspec Pro, Analytical Spectral Devices, Inc., Boulder, CO) was used to measure canopy radiances 1 m above plant canopies with a 22deg field of view and a 0deg nadir view zenith angle. Canopy and plant measurements were made at the R3 grain fill reproductive stage on 3-4 replicate N application plots provided seasonal inputs of 280, 140, 70, and 28 kg N/ha. Leaf level measurements were also made which included ChlF, photosynthesis, and leaf constituents (photosynthetic pigment, carbon (C), and N contents). Crop yields were determined at harvest. SIF intensities for ChlF were derived directly from canopy reflectance spectra in specific narrowband regions associated with atmospheric oxygen absorption features centered at 688 and 760 nm. The red/far-red S F ratio derived from these field reflectance spectra successfully discriminated foliar pigment levels (e.g., total chlorophyll, Chl) associated with N application rates in both corn crops. This canopy-level spectral ratio was also positively correlated to the foliar C/N ratio (r = 0.89, n = go), as was a leaf-level steady state fluorescence ratio (Fs/Chl, r = 0.92). The latter ratio was inversely correlated with crop grain yield (Kg 1 ha) (r = 0.9). This study has relevance to future passive satellite remote sensing approaches to monitoring C dynamics from space.

On the prediction of threshold friction velocity of wind erosion using soil reflectance spectroscopy

USGS Publications Warehouse

Li, Junran; Flagg, Cody B.; Okin, Gregory S.; Painter, Thomas H.; Dintwe, Kebonye; Belnap, Jayne

2015-01-01

Current approaches to estimate threshold friction velocity (TFV) of soil particle movement, including both experimental and empirical methods, suffer from various disadvantages, and they are particularly not effective to estimate TFVs at regional to global scales. Reflectance spectroscopy has been widely used to obtain TFV-related soil properties (e.g., moisture, texture, crust, etc.), however, no studies have attempted to directly relate soil TFV to their spectral reflectance. The objective of this study was to investigate the relationship between soil TFV and soil reflectance in the visible and near infrared (VIS–NIR, 350–2500 nm) spectral region, and to identify the best range of wavelengths or combinations of wavelengths to predict TFV. Threshold friction velocity of 31 soils, along with their reflectance spectra and texture were measured in the Mojave Desert, California and Moab, Utah. A correlation analysis between TFV and soil reflectance identified a number of isolated, narrow spectral domains that largely fell into two spectral regions, the VIS area (400–700 nm) and the short-wavelength infrared (SWIR) area (1100–2500 nm). A partial least squares regression analysis (PLSR) confirmed the significant bands that were identified by correlation analysis. The PLSR further identified the strong relationship between the first-difference transformation and TFV at several narrow regions around 1400, 1900, and 2200 nm. The use of PLSR allowed us to identify a total of 17 key wavelengths in the investigated spectrum range, which may be used as the optimal spectral settings for estimating TFV in the laboratory and field, or mapping of TFV using airborne/satellite sensors.

Arterial waves in humans during peripheral vascular surgery.

PubMed

Khir, A W; Henein, M Y; Koh, T; Das, S K; Parker, K H; Gibson, D G

2001-12-01

The purpose of this study was to investigate the effect of aortic clamping on arterial waves during peripheral vascular surgery. We measured pressure and velocity simultaneously in the ascending aorta, in ten patients (70+/-5 years) with aortic-iliac disease intra-operatively. Pressure was measured using a catheter tip manometer, and velocity was measured using Doppler ultrasound. Data were collected before aortic clamping, during aortic clamping and after unclamping. Hydraulic work in the aortic root was calculated from the measured data, the reflected waves were determined by wave-intensity analysis and wave speed was determined by the PU-loop (pressure-velocity-loop) method; a new technique based on the 'water-hammer' equation. The wave speed is approx. 32% (P<0.05) higher during clamping than before clamping. Although the peak intensity of the reflected wave does not alter with clamping, it arrives 30 ms (P<0.05) earlier and its duration is 25% (P<0.05) longer than before clamping. During clamping, left ventricule (LV) hydraulic systolic work and the energy carried by the reflected wave increased by 27% (P<0.05) and 20% (P<0.05) respectively, compared with before clamping. The higher wave speed during clamping explains the earlier arrival of the reflected waves suggesting an increase in the afterload, since the LV has to overcome earlier reflected compression waves. The longer duration of the reflected wave during clamping is associated with an increase in the total energy carried by the wave, which causes an increase in hydraulic work. Increased hydraulic work during clamping may increase LV oxygen consumption, provoke myocardial ischaemia and hence contribute to the intra-operative impairment of LV function known in patients with peripheral vascular disease.

Electromagnetic Tunneling and Resonances in Pseudochiral Omega Slabs

PubMed Central

Razzaz, Faroq; Alkanhal, Majeed A. S.

2017-01-01

This paper presents theoretical investigation of the electromagnetic wave tunneling and anomalous transmission around the trapped modes in a pseudochiral omega slab. The dispersion relation, the conditions of the trapped modes, and the evanescent wave coupling and tunneling in two different reciprocal pseudochiral omega slab structures are derived. The Berreman’s matrix method is applied to obtain the transmission coefficients across the pseudochiral omega slab. When the structure is perturbed, a resonance phenomenon is detected around the trapped modes. This resonance results in transmission anomalies (total transmission and total reflection) and dramatic field amplifications around the trapped modes. The number of the discrete trapped modes and then the resonance frequencies are prescribed by the parameters of the pseudochiral omega slab such as the value of the omega parameter and its orientation and the slab thickness. PMID:28165058

miR-MaGiC improves quantification accuracy for small RNA-seq.

PubMed

Russell, Pamela H; Vestal, Brian; Shi, Wen; Rudra, Pratyaydipta D; Dowell, Robin; Radcliffe, Richard; Saba, Laura; Kechris, Katerina

2018-05-15

Many tools have been developed to profile microRNA (miRNA) expression from small RNA-seq data. These tools must contend with several issues: the small size of miRNAs, the small number of unique miRNAs, the fact that similar miRNAs can be transcribed from multiple loci, and the presence of miRNA isoforms known as isomiRs. Methods failing to address these issues can return misleading information. We propose a novel quantification method designed to address these concerns. We present miR-MaGiC, a novel miRNA quantification method, implemented as a cross-platform tool in Java. miR-MaGiC performs stringent mapping to a core region of each miRNA and defines a meaningful set of target miRNA sequences by collapsing the miRNA space to "functional groups". We hypothesize that these two features, mapping stringency and collapsing, provide more optimal quantification to a more meaningful unit (i.e., miRNA family). We test miR-MaGiC and several published methods on 210 small RNA-seq libraries, evaluating each method's ability to accurately reflect global miRNA expression profiles. We define accuracy as total counts close to the total number of input reads originating from miRNAs. We find that miR-MaGiC, which incorporates both stringency and collapsing, provides the most accurate counts.

Orthotopic AY-27 rat bladder urothelial cell carcinoma model presented an elevated methemoglobin proportion in the increased total hemoglobin content when evaluated in vivo by single-fiber reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Sun, Tengfei; Davis, Carole A.; Hurst, Robert E.; Slaton, Joel W.; Piao, Daqing

2017-02-01

In vivo single-fiber reflectance spectroscopy (SfRS) was performed on an orthotopic AY-27 rat bladder urothelial cell carcinoma model to explore potential spectroscopic features revealing neoplastic changes. AY-27 bladder tumor cells were intravesically instilled in four rats and allowed to implant and grow for one week, with two additional rats as the control. A total of 107 SfRS measurements were taken from 27 sites on two control bladders and 80 from four AY-27 treated bladders. The spectral profiles obtained from AY-27 treated bladders revealed various levels of a methemoglobin (MetHb) characteristic spectral feature around 635nm. A multisegment spectral analysis method estimated concentrations of five chromophore compositions including oxyhemoglobin, deoxyhemoglobin, MetHb, lipid and water. The total hemoglobin concentration ([HbT]), the MetHb proportion in the total hemoglobin and the lipid volume content showed possible correlations. The 80 measurements from the AY-27 treated bladders could separate to three sub-sets according to the MetHb proportion. Specifically, 72 were in subset 1 with low proportion (5.3%<[MetHb]<7%), 6 in subset 2 with moderate proportion (7%<[MetHb]<30%), and 2 in subset 3 with significant proportion (>30%). When grouped according to [MetHB], the [HbT] increased from 368 μM of subset 1 to 488 μM of subset 2 to 541 μM of subset 3, in comparison to the 285 μM of the control. The increased total hemoglobin and the elevation of MetHb proportion may signify angiogenesis and degradation in hemoglobin oxygen-transport. Additionally, the lipid volume content decreased from 2.58% in the control to <0.2% in the tumor groups, indicating disruption of subepithelium tissue architecture.

Sensitivity Studies for Space-based Measurements of Atmospheric Total Column Carbon Dioxide Using Reflected Sunlight

NASA Technical Reports Server (NTRS)

Mao, Jianping; Kawa, S. Randolph

2003-01-01

A series of sensitivity studies is carried out to explore the feasibility of space-based global carbon dioxide (CO2) measurements for global and regional carbon cycle studies. The detection method uses absorption of reflected sunlight in the CO2 vibration-rotation band at 1.58 micron. The sensitivities of the detected radiances are calculated using the line-by-line model (LBLRTM), implemented with the DISORT (Discrete Ordinates Radiative Transfer) model to include atmospheric scattering in this band. The results indicate that (a) the small (approx.1%) changes in CO2 near the Earth's surface are detectable in this CO2 band provided adequate sensor signal-to-noise ratio and spectral resolution are achievable; (b) the effects of other interfering constituents, such as water vapor, aerosols and cirrus clouds, on the radiance are significant but the overall effects of the modification of light path length on total back-to-space radiance sensitivity to CO2 change are minor for general cases, which means that generally the total column CO2 can be derived in high precision from the ratio of the on-line center to off-line radiances; (c) together with CO2 gas absorption aerosol/cirrus cloud layer has differential scattering which may result in the modification of on-line to off-line radiance ratio which could lead a large bias in the total column CO2 retrieval. Approaches to correct such bias need further investigation. (d) CO2 retrieval requires good knowledge of the atmospheric temperature profile, e.g. approximately 1K RMS error in layer temperature, which is achievable from new atmospheric sounders in the near future; (e) the atmospheric path length, over which the CO2 absorption occurs, should be known in order to correctly interpret horizontal gradients of CO2 from the total column CO2 measurement; thus an additional sensor for surface pressure measurement needs to be attached for a complete measurement package.

Limitations of subjective cognitive load measures in simulation-based procedural training.

PubMed

Naismith, Laura M; Cheung, Jeffrey J H; Ringsted, Charlotte; Cavalcanti, Rodrigo B

2015-08-01

The effective implementation of cognitive load theory (CLT) to optimise the instructional design of simulation-based training requires sensitive and reliable measures of cognitive load. This mixed-methods study assessed relationships between commonly used measures of total cognitive load and the extent to which these measures reflected participants' experiences of cognitive load in simulation-based procedural skills training. Two groups of medical residents (n = 38) completed three questionnaires after participating in simulation-based procedural skills training sessions: the Paas Cognitive Load Scale; the NASA Task Load Index (TLX), and a cognitive load component (CLC) questionnaire we developed to assess total cognitive load as the sum of intrinsic load (how complex the task is), extraneous load (how the task is presented) and germane load (how the learner processes the task for learning). We calculated Pearson's correlation coefficients to assess agreement among these instruments. Group interviews explored residents' perceptions about how the simulation sessions contributed to their total cognitive load. Interviews were audio-recorded, transcribed and subjected to qualitative content analysis. Total cognitive load scores differed significantly according to the instrument used to assess them. In particular, there was poor agreement between the Paas Scale and the TLX. Quantitative and qualitative findings supported intrinsic cognitive load as synonymous with mental effort (Paas Scale), mental demand (TLX) and task difficulty and complexity (CLC questionnaire). Additional qualitative themes relating to extraneous and germane cognitive loads were not reflected in any of the questionnaires. The Paas Scale, TLX and CLC questionnaire appear to be interchangeable as measures of intrinsic cognitive load, but not of total cognitive load. A more complete understanding of the sources of extraneous and germane cognitive loads in simulation-based training contexts is necessary to determine how best to measure and assess their effects on learning and performance outcomes. © 2015 John Wiley & Sons Ltd.

Using bathymetry and reflective seismic profiles to tests a suspected link between melt flux and cumulative fault heave at mid-ocean ridges

NASA Astrophysics Data System (ADS)

Haughton, G.; Murton, B. J.; Le Bas, T.; Henstock, T.

2017-12-01

The interplay between magma supply and spreading rate is believed to play a major role in determining large scale seafloor morphology. Here we use bathymetry to test this relationship in areas with similar spreading rates and differing magma supplies. By using open source bathymetry data we have developed a repeatable, automated method for categorising seafloor cumulative fault heave and then attempt to identify the controlling variables. We measure the total apparent fault heave along axis and off-axis at 29°N and 60°N on the Mid-Atlantic Ridge then compare this to proxies for deformation and magma supply. Two approaches are adopted for identifying faults: one using bathymetry and the other spreading-parallel seismic reflection data. The first re-examines the orthogonally spreading Broken Spur segment (26°N) spreading at 23 mm yr-1 (full rate). The other examines the Reykjanes Ridge (60°N) spreading obliquely at 21 mm yr-1 (full rate), which may be influenced by the Icelandic hotspot. Each have contrasting residual depth and structure, with the former being typical of slow spreading ridges, with marked axial valleys, whereas the latter is more typical of fast spreading ridge morphology, with smooth axial rise. We find that high total heave (indicating high tectonic spreading) on the Broken Spur segment does not correlate with high mantle Bouguer anomalies (indicating thin crust and low melt flux). From this we hypothesise that total heave on the large scale at the Broken Spur segment is not controlled by crustal thickness or melt supply. At the Raykjanes Ridge, V-shaped ridges have thicker crust (measured seismically) which converge south of Iceland. These are thought to reflect transient (every 4-6 Myrs) pulses of hot mantle radiating away from the Iceland plume. We find ridge-symmetrical variation in fault heave but with a lower frequency (6-8 Myrs) and longer wavelength (3-7 Myrs) than the V-shaped ridges. Our analysis shows that plume pulses do not correlate with cumulative fault heave. Our results raise questions about the relationship between melt flux and tectonic stretching. Other factors may be more significant such as spreading geometry, lithospheric temperature, hydrothermal alteration, or mantle heterogeneities that may not be reflected in melt productivity or faulting.

A normalisation framework for (hyper-)spectral imagery

NASA Astrophysics Data System (ADS)

Grumpe, Arne; Zirin, Vladimir; Wöhler, Christian

2015-06-01

It is well known that the topography has an influence on the observed reflectance spectra. This influence is not compensated by spectral ratios, i.e. the effect is wavelength dependent. In this work, we present a complete normalisation framework. The surface temperature is estimated based on the measured surface reflectance. To normalise the spectral reflectance with respect to a standard illumination geometry, spatially varying reflectance parameters are estimated based on a non-linear reflectance model. The reflectance parameter estimation has one free parameter, i.e. a low-pass function, which sets the scale of the spatial-variance, i.e. the lateral resolution of the reflectance parameter maps. Since the local surface topography has a major influence on the measured reflectance, often neglected shading information is extracted from the spectral imagery and an existing topography model is refined to image resolution. All methods are demonstrated on the Moon Mineralogy Mapper dataset. Additionally, two empirical methods are introduced that deal with observed systematic reflectance changes in co-registered images acquired at different phase angles. These effects, however, may also be caused by the sensor temperature, due to its correlation with the phase angle. Surface temperatures above 300 K are detected and are very similar to a reference method. The proposed method, however, seems more robust in case of absorptions visible in the reflectance spectrum near 2000 nm. By introducing a low-pass into the computation of the reflectance parameters, the reflectance behaviour of the surfaces may be derived at different scales. This allows for an iterative refinement of the local surface topography using shape from shading and the computation reflectance parameters. The inferred parameters are derived from all available co-registered images and do not show significant influence of the local surface topography. The results of the empirical correction show that both proposed methods greatly reduce the influence of different phase angles or sensor temperatures.

Four-color single-molecule fluorescence with noncovalent dye labeling to monitor dynamic multimolecular complexes.

PubMed

DeRocco, Vanessa; Anderson, Trevor; Piehler, Jacob; Erie, Dorothy A; Weninger, Keith

2010-11-01

To enable studies of conformational changes within multimolecular complexes, we present a simultaneous, four-color single molecule fluorescence methodology implemented with total internal reflection illumination and camera-based, wide-field detection. We further demonstrate labeling histidine-tagged proteins noncovalently with Tris-nitrilotriacetic acid (Tris-NTA)-conjugated dyes to achieve single molecule detection. We combine these methods to colocalize the mismatch repair protein MutSα on DNA while monitoring MutSα-induced DNA bending using Förster resonance energy transfer (FRET) and to monitor assembly of membrane-tethered SNARE protein complexes.

Four-color single molecule fluorescence with noncovalent dye labeling to monitor dynamic multimolecular complexes

PubMed Central

DeRocco, Vanessa C.; Anderson, Trevor; Piehler, Jacob; Erie, Dorothy A.; Weninger, Keith

2010-01-01

To allow studies of conformational changes within multi-molecular complexes, we present a simultaneous, 4-color single molecule fluorescence methodology implemented with total internal reflection illumination and camera based, wide-field detection. We further demonstrate labeling histidine-tagged proteins non-covalently with tris-Nitrilotriacetic acid (tris-NTA) conjugated dyes to achieve single molecule detection. We combine these methods to co-localize the mismatch repair protein MutSα on DNA while monitoring MutSα-induced DNA bending using Förster resonance energy transfer (FRET) and to monitor assembly of membrane-tethered SNARE protein complexes. PMID:21091445

Characterization of double oxide system Cu-Cr-O supported on γ-Al2O3

NASA Astrophysics Data System (ADS)

Cherkezova-Zheleva, Z.; Kolev, H.; Krstić, J.; Dimitrov, D.; Ivanov, K.; Loncarević, D.; Jovanović, D.; Mitov, I.

2009-09-01

Series of alumina supported chromium-copper catalysts were prepared by co-impregnation method. The samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and UV-visible diffuse reflectance spectroscopy. Dispersion and porosity was also obtained. The experimental and catalytic test results have drawn a conclusion that an interaction between copper and chromium ions takes place. This interaction is responsible for the enhanced catalytic activity of studied catalysts in reaction of total oxidation of industrial formaldehyde production exhaust gas, which contains CO, dimethyl ether and methanol as main components.

Error analysis of finite difference schemes applied to hyperbolic initial boundary value problems

NASA Technical Reports Server (NTRS)

Skollermo, G.

1979-01-01

Finite difference methods for the numerical solution of mixed initial boundary value problems for hyperbolic equations are studied. The reported investigation has the objective to develop a technique for the total error analysis of a finite difference scheme, taking into account initial approximations, boundary conditions, and interior approximation. Attention is given to the Cauchy problem and the initial approximation, the homogeneous problem in an infinite strip with inhomogeneous boundary data, the reflection of errors in the boundaries, and two different boundary approximations for the leapfrog scheme with a fourth order accurate difference operator in space.

Direct measurements of protein-stabilized gold nanoparticle interactions.

PubMed

Eichmann, Shannon L; Bevan, Michael A

2010-09-21

We report integrated video and total internal reflection microscopy measurements of protein stabilized 110 nm Au nanoparticles confined in 280 nm gaps in physiological media. Measured potential energy profiles display quantitative agreement with Brownian dynamic simulations that include hydrodynamic interactions and camera exposure time and noise effects. Our results demonstrate agreement between measured nonspecific van der Waals and adsorbed protein interactions with theoretical potentials. Confined, lateral nanoparticle diffusivity measurements also display excellent agreement with predictions. These findings provide a basis to interrogate specific biomacromolecular interactions in similar experimental configurations and to design future improved measurement methods.

Biomimetic graphene sensors: functionalizing graphene with peptides

NASA Astrophysics Data System (ADS)

Ishigami, Masa; Nyon Kim, Sang; Naik, Rajesh; Tatulian, Suren A.; Katoch, Jyoti

2012-02-01

Non-covalent biomimetic functionalization of graphene using peptides is one of more promising methods for producing novel sensors with high sensitivity and selectivity. Here we combine atomic force microscopy, Raman spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopy to investigate peptide binding to graphene and graphite. We choose to study a dodecamer peptide identified with phage display to possess affinities for graphite and we find that the peptide forms a complex mesh-like structure upon adsorption on graphene. Moreover, optical spectroscopy reveals that the peptide binds non-covalently to graphene and possesses an optical signature of an ?-helical conformation on graphene.

The effect of ultrasonic irradiation on the crystallinity of nano-hydroxyapatite produced via the wet chemical method.

PubMed

Barbosa, Michelle C; Messmer, Nigel R; Brazil, Tayra R; Marciano, Fernanda R; Lobo, Anderson O

2013-07-01

Nanohydroxyapatite (nHAp) powders were produced via aqueous precipitation by adopting four different experimental conditions, assisted or non-assisted by ultrasound irradiation (UI). The nHAp powders were characterized by X-ray diffraction, energy-dispersive X-ray fluorescence, Raman and attenuated total reflection Fourier transform infrared spectroscopies, which showed typical surface chemical compositions of nHAp. Analysis found strong connections between UI and the crystallization process, crystal growth properties, as well as correlations between calcination and substitution reactions. Copyright © 2013 Elsevier B.V. All rights reserved.

Surface roughness effects on the solar reflectance of cool asphalt shingles

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

Akbari, Hashem; Berdahl, Paul; Akbari, Hashem

2008-02-17

We analyze the solar reflectance of asphalt roofing shingles that are covered with pigmented mineral roofing granules. The reflecting surface is rough, with a total area approximately twice the nominal area. We introduce a simple analytical model that relates the 'micro-reflectance' of a small surface region to the 'macro-reflectance' of the shingle. This model uses a mean field approximation to account for multiple scattering effects. The model is then used to compute the reflectance of shingles with a mixture of different colored granules, when the reflectances of the corresponding mono-color shingles are known. Simple linear averaging works well, with smallmore » corrections to linear averaging derived for highly reflective materials. Reflective base granules and reflective surface coatings aid achievement of high solar reflectance. Other factors that influence the solar reflectance are the size distribution of the granules, coverage of the asphalt substrate, and orientation of the granules as affected by rollers during fabrication.« less

Analytical resource assessment method for continuous (unconventional) oil and gas accumulations - The "ACCESS" Method

USGS Publications Warehouse

Crovelli, Robert A.; revised by Charpentier, Ronald R.

2012-01-01

The U.S. Geological Survey (USGS) periodically assesses petroleum resources of areas within the United States and the world. The purpose of this report is to explain the development of an analytic probabilistic method and spreadsheet software system called Analytic Cell-Based Continuous Energy Spreadsheet System (ACCESS). The ACCESS method is based upon mathematical equations derived from probability theory. The ACCESS spreadsheet can be used to calculate estimates of the undeveloped oil, gas, and NGL (natural gas liquids) resources in a continuous-type assessment unit. An assessment unit is a mappable volume of rock in a total petroleum system. In this report, the geologic assessment model is defined first, the analytic probabilistic method is described second, and the spreadsheet ACCESS is described third. In this revised version of Open-File Report 00-044 , the text has been updated to reflect modifications that were made to the ACCESS program. Two versions of the program are added as appendixes.

Publications - GMC 13 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 13 Publication Details Title: Total organic carbon, rock-eval pyrolysis and vitrinite information. Bibliographic Reference Phillips Petroleum Company, 1983, Total organic carbon, rock-eval K) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon; Vitrinite Reflectance Top of Page

Publications - GMC 127 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 127 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite information. Bibliographic Reference Unknown, 1989, Total organic carbon, rock-eval pyrolysis, and vitrinite ) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon; Vitrinite Reflectance Top of Page Department

An analytical two-flow model to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance

NASA Astrophysics Data System (ADS)

Ma, Wei-Ming

1997-06-01

An analytical two-flow model is derived from the radiative transfer equation to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance. The model utilizes unique boundary conditions, including the surface slope of the downwelling and upwelling irradiance as well as the influence of wind and bottom reflectance on simulated surface reflectance. The developed model provides a simple mathematical concept for understanding the irradiant light flux and associated processes in coastal or fresh water as well as turbid estuarine waters. The model is applied to data from the Banana River and coastal Atlantic Ocean water off the east coast of central Florida, USA. The two-flow irradiance model is capable of simulating realistic above-surface reflectance signatures under wind-roughened air-water surface given realistic input parameters including a specular flux conversion coefficient, absorption coefficient, backscattering coefficient, atmospheric visibility, bottom reflectance, and water depth. The root-mean-squared error of the calculated above-surface reflectances is approximately 3% in the Banana River and is less than 15% in coastal Atlantic Ocean off the east of Florida. Result of the subsurface reflectance sensitivity analysis indicates that the specular conversion coefficient is the most sensitive parameter in the model, followed by the beam attenuation coefficient, absorption coefficient, water depth, backscattering coefficient, specular irradiance, diffuse irradiance, bottom reflectance, and wind speed. On the other hand, result of the above-surface reflectance sensitivity analysis indicates that the wind speed is the most important parameter, followed by bottom reflectance, attenuation coefficient, water depth, conversion coefficient, specular irradiance, downwelling irradiance, absorption coefficient, and backscattering coefficient. Model results depend on the accuracy of these parameters to a large degree and more important the water depth and value of the bottom reflectance. The results of this work indicates little change of subsurface or in-water reflectances, due to variations of wind speed and observation angle. Simulations of the wind effect on the total downwelling irradiance from the two- flow model indicates that the total downwelling irradiance just below a wind-roughened water surface increases to about 1% of the total downwelling irradiance on a calm water surface when the sun is near zenith and increases to about 3% when the sun is near the horizon. This analytically based model, solved or developed utilizing the unique boundary conditions, can be applied to remote sensing of oceanic upper mixed layer dynamics, plant canopies, primary production, and shallow water environments with different bottom type reflectances. Future applications may include determining effects of sediment resuspension of bottom sediments in the bottom boundary layer on remotely sensed data.

System and method for optically locating microchannel positions

DOEpatents

Brewer, Laurence R.; Kimbrough, Joseph; Balch, Joseph; Davidson, J. Courtney

2001-01-01

A system and method is disclosed for optically locating a microchannel position. A laser source generates a primary laser beam which is directed at a microchannel plate. The microchannel plates include microchannels at various locations. A back-reflectance beam detector receives a back-reflected beam from the plate. The back-reflected beam is generated when the primary beam reflects off of the plate. A photodiode circuit generates a trigger signal when the back-reflected beam exceeds a predetermined threshold, indicating a presence of the microchannel. The method of the present invention includes the steps of generating a primary beam, directing the primary beam to a plate containing a microchannel, receiving from the plate a back-reflected beam generated in response to the primary beam, and generating a trigger signal when the back-reflected beam exceeds a predetermined threshold which corresponds to a presence of the microchannel.

Mapping soil total nitrogen of cultivated land at county scale by using hyperspectral image

NASA Astrophysics Data System (ADS)

Gu, Xiaohe; Zhang, Li Yan; Shu, Meiyan; Yang, Guijun

2018-02-01

Monitoring total nitrogen content (TNC) in the soil of cultivated land quantitively and mastering its spatial distribution are helpful for crop growing, soil fertility adjustment and sustainable development of agriculture. The study aimed to develop a universal method to map total nitrogen content in soil of cultivated land by HSI image at county scale. Several mathematical transformations were used to improve the expression ability of HSI image. The correlations between soil TNC and the reflectivity and its mathematical transformations were analyzed. Then the susceptible bands and its transformations were screened to develop the optimizing model of map soil TNC in the Anping County based on the method of multiple linear regression. Results showed that the bands of 14th, 16th, 19th, 37th and 60th with different mathematical transformations were screened as susceptible bands. Differential transformation was helpful for reducing the noise interference to the diagnosis ability of the target spectrum. The determination coefficient of the first order differential of logarithmic transformation was biggest (0.505), while the RMSE was lowest. The study confirmed the first order differential of logarithm transformation as the optimal inversion model for soil TNC, which was used to map soil TNC of cultivated land in the study area.

Rapid non-destructive assessment of pork edible quality by using VIS/NIR spectroscopic technique

NASA Astrophysics Data System (ADS)

Zhang, Leilei; Peng, Yankun; Dhakal, Sagar; Song, Yulin; Zhao, Juan; Zhao, Songwei

2013-05-01

The objectives of this research were to develop a rapid non-destructive method to evaluate the edible quality of chilled pork. A total of 42 samples were packed in seal plastic bags and stored at 4°C for 1 to 21 days. Reflectance spectra were collected from visible/near-infrared spectroscopy system in the range of 400nm to 1100nm. Microbiological, physicochemical and organoleptic characteristics such as the total viable counts (TVC), total volatile basic-nitrogen (TVB-N), pH value and color parameters L* were determined to appraise pork edible quality. Savitzky-Golay (SG) based on five and eleven smoothing points, Multiple Scattering Correlation (MSC) and first derivative pre-processing methods were employed to eliminate the spectra noise. The support vector machines (SVM) and partial least square regression (PLSR) were applied to establish prediction models using the de-noised spectra. A linear correlation was developed between the VIS/NIR spectroscopy and parameters such as TVC, TVB-N, pH and color parameter L* indexes, which could gain prediction results with Rv of 0.931, 0.844, 0.805 and 0.852, respectively. The results demonstrated that VIS/NIR spectroscopy technique combined with SVM possesses a powerful assessment capability. It can provide a potential tool for detecting pork edible quality rapidly and non-destructively.

Characterizing and authenticating Montilla-Moriles PDO vinegars using near infrared reflectance spectroscopy (NIRS) technology.

PubMed

De la Haba, María-José; Arias, Mar; Ramírez, Pilar; López, María-Isabel; Sánchez, María-Teresa

2014-02-20

This study assessed the potential of near infrared (NIR) spectroscopy as a non-destructive method for characterizing Protected Designation of Origin (PDO) "Vinagres de Montilla-Moriles" wine vinegars and for classifying them as a function of the manufacturing process used. Three spectrophotometers were evaluated for this purpose: two monochromator instruments (Foss NIRSystems 6500 SY-I and Foss NIRSystems 6500 SY-II; spectral range 400-2,500 nm in both cases) and a diode-array instrument (Corona 45 VIS/NIR; spectral range 380-1,700 nm). A total of 70 samples were used to predict major chemical quality parameters (total acidity, fixed acidity, volatile acidity, pH, dry extract, ash, acetoin, methanol, total polyphenols, color (tonality and intensity), and alcohol content), and to construct models for the classification of vinegars as a function of the manufacturing method used. The results obtained indicate that this non-invasive technology can be used successfully by the vinegar industry and by PDO regulators for the routine analysis of vinegars in order to authenticate them and to detect potential fraud. Slightly better results were achieved with the two monochromator instruments. The findings also highlight the potential of these NIR instruments for predicting the manufacturing process used, this being of particular value for the industrial authentication of traditional wine vinegars.

Pelvic kinematic method for determining vertical jump height.

PubMed

Chiu, Loren Z F; Salem, George J

2010-11-01

Sacral marker and pelvis reconstruction methods have been proposed to approximate total body center of mass during relatively low intensity gait and hopping tasks, but not during a maximum effort vertical jumping task. In this study, center of mass displacement was calculated using the pelvic kinematic method and compared with center of mass displacement using the ground-reaction force-impulse method, in experienced athletes (n = 13) performing restricted countermovement vertical jumps. Maximal vertical jumps were performed in a biomechanics laboratory, with data collected using an 8-camera motion analysis system and two force platforms. The pelvis center of mass was reconstructed from retro-reflective markers placed on the pelvis. Jump height was determined from the peak height of the pelvis center of mass minus the standing height. Strong linear relationships were observed between the pelvic kinematic and impulse methods (R² = .86; p < .01). The pelvic kinematic method underestimated jump height versus the impulse method, however, the difference was small (CV = 4.34%). This investigation demonstrates concurrent validity for the pelvic kinematic method to determine vertical jump height.

Health Risk Assessment of Lead Ingestion Exposure by Particle Sizes in Crumb Rubber on Artificial Turf Considering Bioavailability

PubMed Central

Kim, Sunduk; Yang, Ji-Yeon; Kim, Ho-Hyun; Yeo, In-Young; Shin, Dong-Chun

2012-01-01

Objectives The purpose of this study was to assess the risk of ingestion exposure of lead by particle sizes of crumb rubber in artificial turf filling material with consideration of bioavailability. Methods This study estimated the ingestion exposure by particle sizes (more than 250 um or less than 250 um) focusing on recyclable ethylene propylene diene monomer crumb rubber being used as artificial turf filling. Analysis on crumb rubber was conducted using body ingestion exposure estimate method in which total content test method, acid extraction method and digestion extraction method are reflected. Bioavailability which is a calibrating factor was reflected in ingestion exposure estimate method and applied in exposure assessment and risk assessment. Two methods using acid extraction and digestion extraction concentration were compared and evaluated. Results As a result of the ingestion exposure of crumb rubber material, the average lead exposure amount to the digestion extraction result among crumb rubber was calculated to be 1.56×10-4 mg/kg-day for low grade elementary school students and 4.87×10-5 mg/kg-day for middle and high school students in 250 um or less particle size, and that to the acid extraction result was higher than the digestion extraction result. Results of digestion extraction and acid extraction showed that the hazard quotient was estimated by about over 2 times more in particle size of lower than 250 um than in higher than 250 um. There was a case of an elementary school student in which the hazard quotient exceeded 0.1. Conclusions Results of this study confirm that the exposure of lead ingestion and risk level increases as the particle size of crumb rubber gets smaller. PMID:22355803

The World Café: An Innovative Method to Facilitate Reflections on Internationalisation in Higher Education

ERIC Educational Resources Information Center

Estacio, Emee Vida; Karic, Toni

2016-01-01

This article provides an example of how the World Café method can be used as a platform to encourage reflection on internationalisation in higher education. The World Café is a community engagement method that encourages participants to engage in reflection and dialogue in a relaxed and comfortable atmosphere. It promotes the use of multiple…

Distance, Dialogue and Reflection: Interpersonal Reflective Equilibrium as Method for Professional Ethics Education

ERIC Educational Resources Information Center

van den Hoven, Mariëtte; Kole, Jos

2015-01-01

The method of reflective equilibrium (RE) is well known within the domain of moral philosophy, but hardly discussed as a method in professional ethics education. We argue that an interpersonal version of RE is very promising for professional ethics education. We offer several arguments to support this claim. The first group of arguments focus on a…

Layer-by-layer design method for soft-X-ray multilayers

NASA Technical Reports Server (NTRS)

Yamamoto, Masaki; Namioka, Takeshi

1992-01-01

A new design method effective for a nontransparent system has been developed for soft-X-ray multilayers with the aid of graphic representation of the complex amplitude reflectance in a Gaussian plane. The method provides an effective means of attaining the absolute maximum reflectance on a layer-by-layer basis and also gives clear insight into the evolution of the amplitude reflectance on a multilayer as it builds up. An optical criterion is derived for the selection of a proper pair of materials needed for designing a high-reflectance multilayer. Some examples are given to illustrate the usefulness of this design method.

Mapping polycyclic aromatic hydrocarbon and total toxicity equivalent soil concentrations by visible and near-infrared spectroscopy.

PubMed

Okparanma, Reuben N; Coulon, Frederic; Mayr, Thomas; Mouazen, Abdul M

2014-09-01

In this study, we used data from spectroscopic models based on visible and near-infrared (vis-NIR; 350-2500 nm) diffuse reflectance spectroscopy to develop soil maps of polycyclic aromatic hydrocarbons (PAHs) and total toxicity equivalent concentrations (TTEC) of the PAH mixture. The TTEC maps were then used for hazard assessment of three petroleum release sites in the Niger Delta province of Nigeria (5.317°N, 6.467°E). As the paired t-test revealed, there were non-significant (p > 0.05) differences between soil maps of PAH and TTEC developed with chemically measured and vis-NIR-predicted data. Comparison maps of PAH showed a slight to moderate agreement between measured and predicted data (Kappa coefficient = 0.19-0.56). Using proposed generic assessment criteria, hazard assessment showed that the degree of action for site-specific risk assessment and/or remediation is similar for both measurement methods. This demonstrates that the vis-NIR method may be useful for monitoring hydrocarbon contamination in a petroleum release site. Copyright © 2014 Elsevier Ltd. All rights reserved.

Modeling the reflectance of the lunar regolith by a new method combining Monte Carlo Ray tracing and Hapke's model with application to Chang'E-1 IIM data.

PubMed

Wong, Un-Hong; Wu, Yunzhao; Wong, Hon-Cheng; Liang, Yanyan; Tang, Zesheng

2014-01-01

In this paper, we model the reflectance of the lunar regolith by a new method combining Monte Carlo ray tracing and Hapke's model. The existing modeling methods exploit either a radiative transfer model or a geometric optical model. However, the measured data from an Interference Imaging spectrometer (IIM) on an orbiter were affected not only by the composition of minerals but also by the environmental factors. These factors cannot be well addressed by a single model alone. Our method implemented Monte Carlo ray tracing for simulating the large-scale effects such as the reflection of topography of the lunar soil and Hapke's model for calculating the reflection intensity of the internal scattering effects of particles of the lunar soil. Therefore, both the large-scale and microscale effects are considered in our method, providing a more accurate modeling of the reflectance of the lunar regolith. Simulation results using the Lunar Soil Characterization Consortium (LSCC) data and Chang'E-1 elevation map show that our method is effective and useful. We have also applied our method to Chang'E-1 IIM data for removing the influence of lunar topography to the reflectance of the lunar soil and to generate more realistic visualizations of the lunar surface.

Effect of sample thickness on the extracted near-infrared bulk optical properties of Bacillus subtilis in liquid culture.

PubMed

Dzhongova, Elitsa; Harwood, Colin R; Thennadil, Suresh N

2011-11-01

In order to determine the bulk optical properties of a Bacillus subtilis culture during growth phase we investigated the effect of sample thickness on measurements taken with different measurement configurations, namely total diffuse reflectance and total diffuse transmittance. The bulk optical properties were extracted by inverting the measurements using the radiative transfer theory. While the relationship between reflectance and biomass changes with sample thickness and the intensity (absorbance) levels vary significantly for both reflectance and transmittance measurements, the extracted optical properties show consistent behavior in terms of both the relationship with biomass and magnitude. This observation indicates the potential of bulk optical properties for building models that could be more easily transferable compared to those built using raw measurements.

A small-displacement sensor using total internal reflection theory and surface plasmon resonance technology for heterodyne interferometry.

PubMed

Wang, Shinn-Fwu

2009-01-01

A small-displacement sensor based on total-internal reflection theory and surface plasmon resonance technology is proposed for use in heterodyne interferometry. A small displacement can be obtained simply by measuring the variation in phase difference between s- and p-polarization states with the small-displacement sensor. The theoretical displacement resolution of the small-displacement sensor can reach 0.45 nm. The sensor has some additional advantages, e.g., a simple optical setup, high resolution, high sensitivity and rapid measurement. Its feasibility is also demonstrated.

Microplate-compatible total internal reflection fluorescence microscopy for receptor pharmacology

NASA Astrophysics Data System (ADS)

Chen, Minghan; Zaytseva, Natalya V.; Wu, Qi; Li, Min; Fang, Ye

2013-05-01

We report the use of total internal reflection fluorescence (TIRF) microscopy for analyzing receptor pharmacology and the development of a microplate-compatible TIRF imaging system. Using stably expressed green fluorescence protein tagged β2-adrenergic receptor as the reporter, we found that the activation of different receptors results in distinct kinetic signatures of the TIRF intensity of cells. These TIRF signatures closely resemble the characteristics of their respective label-free dynamic mass redistribution signals in the same cells. This suggests that TIRF in microplate can be used for profiling and screening drugs.

Design of an efficient Fresnel-type lens utilizing double total internal reflection for solar energy collection.

PubMed

Wallhead, Ian; Jiménez, Teresa Molina; Ortiz, Jose Vicente García; Toledo, Ignacio Gonzalez; Toledo, Cristóbal Gonzalez

2012-11-05

A novel of Fresnel-type lens for use as a solar collector has been designed which utilizes double total internal reflection (D-TIR) to optimize collection efficiency for high numerical aperture lenses (in the region of 0.3 to 0.6 NA). Results show that, depending on the numerical aperture and the size of the receiver, a collection efficiency theoretical improvement on the order of 20% can be expected with this new design compared with that of a conventional Fresnel lens.

Reflective practice in speech-language pathology: a scoping review.

PubMed

Caty, Marie-Ève; Kinsella, Elizabeth Anne; Doyle, Philip C

2015-01-01

Within the profession of speech-language pathology, there is limited information related to both conceptual and empirical perspectives of reflective practice. This review considers the key concepts and approaches to reflection and reflective practice that have been published in the speech-language pathology literature in order to identify potential research gaps. A scoping review was conducted using Arksey and O'Malley's (2005) framework. A total of 42 relevant publications were selected for review. The resulting literature mapping revealed that scholarship on reflection and reflective practice in speech-language pathology is limited. Our conceptual mapping pointed to the use of both multiple and generic terms and a lack of conceptual clarity about reflection and reflective practice in speech-language pathology. Two predominant approaches to reflection and reflective practice were identified: written reflection and reflective discussion. Both educational and clinical practice contexts were associated with reflection and reflective practice. Publications reviewed were primarily concerned with reflection and reflective practice by novices and expert practitioners. Based on this review, we posit that there is considerable need for conceptual and empirical work with a goal to support university- and work-based educational initiatives involving reflection and reflective practice in speech-language pathology.

Channel Model Optimization with Reflection Residual Component for Indoor MIMO-VLC System

NASA Astrophysics Data System (ADS)

Chen, Yong; Li, Tengfei; Liu, Huanlin; Li, Yichao

2017-12-01

A fast channel modeling method is studied to solve the problem of reflection channel gain for multiple input multiple output-visible light communications (MIMO-VLC) in the paper. For reducing the computational complexity when associating with the reflection times, no more than 3 reflections are taken into consideration in VLC. We think that higher order reflection link consists of corresponding many times line of sight link and firstly present reflection residual component to characterize higher reflection (more than 2 reflections). We perform computer simulation results for point-to-point channel impulse response, receiving optical power and receiving signal to noise ratio. Based on theoretical analysis and simulation results, the proposed method can effectively reduce the computational complexity of higher order reflection in channel modeling.

Reflection measurement of waveguide-injected high-power microwave antennas.

PubMed

Yuan, Chengwei; Peng, Shengren; Shu, Ting; Zhang, Qiang; Zhao, Xuelong

2015-12-01

A method for reflection measurements of High-power Microwave (HPM) antennas excited with overmoded waveguides is proposed and studied systemically. In theory, principle of the method is proposed and the data processing formulas are developed. In simulations, a horn antenna excited by a TE11 mode exciter is examined and its reflection is calculated by CST Microwave Studio and by the method proposed in this article, respectively. In experiments, reflection measurements of two HPM antennas are conducted, and the measured results are well consistent with the theoretical expectations.

Laboratory and field measurements of upwelled radiance and reflectance spectra of suspended James River sediments near Hopewell, Virginia

NASA Technical Reports Server (NTRS)

Whilock, C. H.; Witte, W. G.; Gurganus, E. A.; Usry, J. W.

1978-01-01

Spectral reflectance characteristics of suspended Bermuda Hundred and Bailey Bay bottom sediments taken from the Hopewell, Va., area were measured in the laboratory for water mixture total suspended solids concentrations between 4 and 173 parts per million. Field spectral reflectance measurements were made of the James River waters near Bermuda Hundred on two occasions. The results of these tests indicate that both Bermuda Hundred and Bailey Bay suspended sediments produce their strongest reflectance in the green and red regions of the spectrum.

Publications - GMC 137 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 137 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Reference Unknown, 1989, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance data of Report Report Information gmc137.pdf (47.0 K) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic

Publications - GMC 100 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 100 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Unknown, 1988, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance data of ditch cuttings Information gmc100.pdf (317.0 K) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon; Vitrinite

Publications - GMC 26 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 26 Publication Details Title: Geochemical data (total organic carbon, rock-eval pyrolysis, and Reference Unknown, 1984, Geochemical data (total organic carbon, rock-eval pyrolysis, and vitrinite ; Total Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources, Division of

Publications - GMC 29 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 29 Publication Details Title: Geochemical analysis (total organic carbon, rock-eval pyrolysis Reference Minder, Michael, and Shell Oil Company, 1985, Geochemical analysis (total organic carbon, rock ; Total Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources, Division of

Publications - GMC 25 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 25 Publication Details Title: Geochemical analysis (total organic carbon, rock-eval pyrolysis Reference Unknown, 1984, Geochemical analysis (total organic carbon, rock-eval pyrolysis, kerogen type ; Total Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources, Division of

Publications - GMC 144 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 144 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite for more information. Bibliographic Reference Unknown, 1989, Total organic carbon, rock-eval pyrolysis gmc144.pdf (104.0 K) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon; Vitrinite Reflectance

Publications - GMC 125 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 125 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Reference Cunningham, K., and Shell Oil Company, 1989, Total organic carbon, rock-eval pyrolysis, and Pyrolysis; Total Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources, Division

Publications - GMC 141 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 141 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Reference Unknown, 1989, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance data of Report Report Information gmc141.pdf (70.0 K) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic

Publications - GMC 101 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 101 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Unknown, 1988, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance data of ditch cuttings Information gmc101.pdf (201.0 K) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon; Vitrinite

Publications - GMC 19 | Alaska Division of Geological & Geophysical Surveys

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DGGS GMC 19 Publication Details Title: Geochemical analysis (total organic carbon-rock-eval, vitrinite information. Bibliographic Reference Unknown, [n.d.], Geochemical analysis (total organic carbon-rock-eval K) Keywords Total Organic Carbon; Vitrinite Reflectance Top of Page Department of Natural Resources

Publications - GMC 27 | Alaska Division of Geological & Geophysical Surveys

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DGGS GMC 27 Publication Details Title: Geochemical analysis (total organic carbon, rock-eval pyrolysis . Bibliographic Reference Unknown, 1995, Geochemical analysis (total organic carbon, rock-eval pyrolysis, and ; Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon; Vitrinite Reflectance Top of Page Department of

Publications - GMC 103 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 103 Publication Details Title: Total organic carbon, rock-eval pyrolysis, and vitrinite Unknown, 1988, Total organic carbon, rock-eval pyrolysis, and vitrinite reflectance data of ditch cuttings Information gmc103.pdf (57.0 K) Keywords Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon; Vitrinite

Publications - GMC 23 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 23 Publication Details Title: Total organic carbon, rock-eval pyrolysis, visual kerogen Unknown, [n.d.], Total organic carbon, rock-eval pyrolysis, visual kerogen/vitrinite reflectance for Information gmc023.pdf (199.0 K) Keywords Kerogen; Pyrolysis; Rock-Eval Pyrolysis; Total Organic Carbon