Scanning Monochromator Research Articles

495 Comparison of two internal markers and Near Infrared Spectroscopy (NIRS) for predicting nutrient digestibility in beef cattle offered diets varying in forage quantity and quality

Abstract The objective of this study was to evaluate acid detergent lignin (ADL), and amylase-treated ash-corrected undigestible neutral detergent fiber after 240 h of ruminal in vitro incubation (uNDF), and near infrared spectroscopy (NIRS) scanning of feces as methods to estimate the digestibility of diets varying in forage quantity and quality when fed to beef cattle. Five total collection (TC) digestibility studies examined 17 different diets and provided individual fecal samples and the corresponding apparent total tract digestibility of nutrients (n = 229). Feed, orts, and fecal samples were analyzed for dry matter (DM), organic matter (OM), nitrogen (N), amylase-treated ash-corrected neutral detergent fiber (aNDFom), acid detergent fiber (ADF), ADL, and uNDF. Previously developed fecal NIRS digestibility calibrations were expanded with dried and ground samples using a FOSS D3F scanning monochromator (FOSS, Eden Prairie, MN). Marker estimated and NIRS predicted nutrient digestibility coefficients were regressed against those determined by TC and goodness-of-fit statistics were applied. Mean concentrations of ADL and uNDF in diets ranged from 23.4 to 96.4 g/kg DM and 67.7 to 200 g/kg DM, respectively, with mean fecal recoveries of 94.2% (SD ± 15.7%) for ADL and 87.5% (SD ± 11.1%) for uNDF. Regression fit statistics between NIRS and TC were not different from one (P > 0.05), with R2 > 0.83 except for ADF digestibility (R2 = 0.63). In comparison, regression statistics between internal markers and TC were poorer with R2 ranging from 0.21 to 0.78. Concordance correlation coefficients (CCC) between NIRS and TC were greater than 0.90 for DM, OM, N, and aNDFom digestibility, and 0.77 for ADF digestibility. The CCC between ADL and TC ranged between 0.63 and 0.82, and between uNDF and TC from 0.26 to 0.78. Correction bias (Cb) was high for all parameters (Cb > 0.76) except for ADF digestibility (Cb = 0.58) as estimated by uNDF. The mean square error of prediction (MSEP) for NIRS predicted digestibility were lower (< 10.7%) than those estimated by internal markers, and most of the error was attributed to random bias (> 97.9%). Random bias for ADL was also greater (>76.1%); however, for uNDF the error was more evenly partitioned into mean bias (46.4% to 49.4%) and random bias (30.4 to 41.9%). Digestibility predictions from NIRS scanning of feces were more accurate and precise than when estimated using the internal markers ADL and uNDF. In the absence of NIRS, ADL estimations appear to be more precise and accurate than uNDF for forage-based diets, with uNDF possibly of greater value for estimating the digestibility of high concentrate diets.

Investigation on plasma ionization process of a micro-cathode arc thruster

Micro-cathode arc thrusters (μCATs) are space propulsion options suitable for microspacecraft, and have recently attracted much attention because of their low electrical power requirements and simple, compact propellant systems. The plasma ionization process, however, is not currently well understood. In this study, a μCAT prototype was designed with the use of different specific materials for each component, enabling the study of the ionization process from the emissive light of excited and ionized states from different elements. ICCD emission spectroscopy and scanning monochromator measurements are conducted inside the electrode channel of a μCAT with a coaxial configuration. The excited state atomic spectral results and ionization state spectral results give us a comprehensive understanding of the behavior of neutral particles and ions during the discharge process of the μCAT. The ionization sequence follows in the order of C+, Al+, Ti+, Cu+, and Ti2+. From the duration of the spectral lines, C I has the shortest duration (16.9 μs), which shows that the ablation of the conductive film is mainly concentrated during the first half of the discharge, while anode and cathode ionization occur over the entire discharge duration. Additionally, Al+ ionization is observed during the discharge process, showing that part of the discharge energy is expended in ionizing the thruster outer shell, resulting in efficiency loss. An ionization ratio of k is proposed in this work to represent the relative ionization of the conductive film and cathode material, aiding us in determining the optimal operation conditions for lifetime extension.

(Invited) Advanced Carbon Nanotube Fluorescence Spectrometry for Novel Applications

Instrumental advances in near-IR fluorescence spectroscopy are enabling new types of measurements involving single-wall carbon nanotubes (SWCNTs). Two unique systems will be described. The first is a two-dimensional fluorescence-detected circular dichroism (FDCD) spectrometer. In this, SWCNT samples are excited by a spectrally selected supercontinuum laser beam that is switched between left- and right-circular polarization in an electro-optic modulator. Near-infrared sample fluorescence emitted in the backward direction is captured and directed to a scanning monochromator with a cooled InGaAs single-channel detector. After amplification and high precision digitization, the modulated signal component is extracted by computer-based phase sensitive detection. The system can measure a sample’s E22 circular dichroism in four spectral modes: 1) conventional FDCD, with scanned visible excitation wavelength and spectrally integrated (zero-order grating) emission detection; 2) Emission-specific FDCD, with scanned visible excitation wavelengths and selected emission wavelength; 3) Emission-scanned FDCD, with selected visible excitation wavelength and scanned emission wavelengths; 4) Excitation-Emission FDCD, with excitation and emission wavelengths both scanned to give two-dimensional data sets. This instrument can spectroscopically resolve enantiomer signals from a single (n,m) species in a racemic SWCNT sample.In a parallel project, developments in SWCNT fluorescence spectrometry are advancing nanotube-based strain measurement technology toward commercialization. Because SWCNT emission wavelengths vary systematically with axial strain, nanotubes in a thin coating on a specimen can serve as optically interrogated strain gauges. We apply this effect to measure strain maps through hyperspectral imaging of SWCNT fluorescence. A rotated band pass filter is used to capture a set of images in multiple spectral slices, from which a custom computer program deduces strain at each of ~105 image pixels and compiles strain maps. We will describe how this apparatus has evolved from a lab prototype into a compact portable system that can make measurements in industrial settings.

Predicting fecal composition, intake, and nutrient digestibility in beef cattle consuming high forage diets using near infrared spectroscopy.

The objective of this study was to develop near infrared spectroscopy (NIRS) calibrations to predict fecal nutrient composition, intake, and diet digestibility from beef cattle fed high forage diets. Heifers were fed 12 different forage-based diets (>95% forage dry matter basis) in 3 total collection digestibility studies, resulting in individual fecal samples and related spectra (n = 135), corresponding nutrient intake, and apparent total tract digestibility (aTTD) data. Fecal samples were also collected from steers grazing two annual and two perennial forage mixtures over two growing seasons. Samples (n = 13/paddock) were composited by paddock resulting in 30 samples from year 1, and 24 from year 2. The grazing fecal spectra (n = 54) were added to the existing fecal composition spectral library. Dried and ground fecal samples were scanned using a FOSS DS2500 scanning monochromator (FOSS, Eden Prairie, MN). Spectra were mathematically treated for detrend and scatter correction and modified partial least squares (MPLS) regression was performed. The coefficient of determination for cross validation (R2cv) and standard error of cross validation (SECV) were used to evaluate the quality of calibrations. Prediction equations were developed for fecal composition [organic matter (OM), nitrogen (N), amylase-treated ash-corrected neutral detergent fiber (aNDFom), acid detergent fiber (ADF), acid detergent lignin (ADL), undigestible NDF after 240 h of in vitro incubation (uNDF), calcium (Ca), and phosphorus (P)], digestibility [DM, OM, aNDFom, N], and intake [DM, OM, aNDFom, N, uNDF]. The calibrations for fecal OM, N, aNDFom, ADF, ADL, uNDF, Ca, P resulted in R2cv between 0.86 and 0.97 and SECV of 1.88, 0.07, 1.70, 1.10, 0.61, 2.00, 0.18, and 0.06, respectively. Equations predicting intake of DM, OM, N, aNDFom, ADL, and uNDF resulted in R2cv values between 0.59 and 0.91, SECV values of 1.12, 1.10, 0.02, 0.69, 0.06, 0.24 kg·d-1, respectively, and SECV values between 0.00 and 0.16 when expressed as % body weight (BW). Digestibility calibrations for DM, OM, aNDFom, and N resulted in R2cv ranging from 0.65 to 0.74 and SECV values from 2.20 to 2.82. We confirm the potential of NIRS to predict fecal chemical composition, digestibility, and intake of cattle fed high forage diets. Future steps include validation of the intake calibration equations for grazing cattle using forage internal marker and modelling energetics of grazing growth performance.

PSVI-6 Predicting Fecal Composition Using Near Infrared Spectroscopy (Nirs): Expanding the Calibration to Include Grazing Beef Samples

Abstract A near-infrared spectroscopy (NIRS) calibration was previously developed to predict fecal composition using samples from beef heifers fed high forage diets ( > 95% forage dry matter basis) during total collection digestibility studies. The objective of the current study was to expand the fecal composition calibration with samples from grazing beef cattle. Fecal samples were collected from beef steers grazing two annual and two perennial forage mixtures over 2 growing seasons. Individual samples (n = 12/paddock) were composited by paddock resulting in 30 samples from year 1, and 24 from year two. Fecal samples were oven dried at 55°C for 48 hours and ground through a 1.0 mm screen prior to scanning on a FOSS DS2500 scanning monochromator (FOSS, Eden Prairie, MN). The grazing fecal spectra (n = 54) was added to the existing library and then mathematically treated for scatter correction. Modified partial least squares (MPLS) regression was performed to develop equations to predict fecal composition [organic matter (OM), nitrogen (N), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), undigestible NDF (uNDF), calcium (Ca), and phosphorus (P)]. The calibrations for fecal OM, N, NDF, ADF, ADL, uNDF, Ca, P resulted in R2CV between 0.86 and 0.96 and SECV of 1.73, 0.07, 1.65, 1.20, 0.63, 1.91, 0.21, and 0.07, respectively. This study confirms the potential of NIRS to predict fecal chemical composition of beef cattle fed high forage or grazing forage diets. Future steps include expansion and further validation of the calibration equations to include digestibility and intake predictions by estimating the internal markers lignin and uNDF.

158 Predicting Intake and Digestibility of Nutrients in Beef Cattle fed High Forage Diets Using Near Infrared Spectroscopy (Nirs) of Feces and Internal Markers

Abstract Objectives of this study were to determine the potential of near infrared-spectroscopy (NIRS) scanning of feces to predict diet digestibility and intake in beef cattle fed high forage diets, and to investigate the use of acid detergent lignin (ADL) and undigestible neutral detergent fiber (uNDF) as internal markers to determine digestibility. Beef heifers were fed 12 different forage-based diets ( > 95% forage dry matter basis) in 3 total collection studies, resulting in individual fecal samples and related spectra (n = 135) corresponding to apparent total tract digestibility (aTTD) and intake data. Dried and ground fecal samples were scanned using a FOSS DS2500 scanning monochromator (FOSS, Eden Prairie, MN). Modified partial least squares (MPLS) regression was performed to develop equations to predict digestibility [dry matter (DM), organic matter (OM), NDF, and nitrogen (N)], and intake [DM, OM, NDF, N, uNDF]. Digestibility prediction equations for DM, OM, NDF, and N resulted in R2CV or 0.72, 0.65, 0.74 and 0.69, respectively, and standard error of cross validation (SECV) between 2.20 to 2.82. Intake calibrations for DM, OM, N, NDF, ADL and uNDF resulted in R2CV values between 0.59 and 0.91, SECV for intake (kg/d) of 1.12, 1.10, 0.02, 0.69, 0.06, 0.24, respectively, SECV for intake % body weight (BW) between 0.00 and 0.16; and SECV for g/kg BW0.75 between 0.60 and 0.86. Significant correlations (P < 0.01) were identified between NDFD determined by aTTD and by the internal marker ADL (r = 0.72) or uNDF (r = 0.57). Developed calibrations predicting marker calculated digestibility resulted in R2CV(SECV) values of 0.85(2.70) and 0.80(2.46) for lignin and uNDF, respectively. We confirm the potential of NIRS to predict digestibility and intake of cattle fed high forage diets. Future steps include further validation of the intake calibration equations using internal marker and energetics modeling.

Bloch Surface Waves Mediated Micro-Spectroscopy.

Micro-spectroscopy is a critical instrument for spectrum analysis in various applications such as chemical and biological analysis, environment detection, and hyperspectral imaging. However, current micro-spectral technique requires bulky and costly spectrometer. In this report, a new type of Bloch surface wave (BSW) based micro-spectrometer is proposed. A single silicon nanoparticle sitting on a dielectric multilayer substrate is used to excite the BSW which acts as a nanoscale unknown source. Taking advantage of the dispersion relations of BSWs, an abundant spectrally related database is formed that is useful for spectrum retrieval applications. Back-focal plane images are used to monitor the change of angular spectrum corresponding to the dispersion relationship of Bloch surface waves. Combined with an iterative algorithm, experimental retrieval of visible-range monochromatic and broadband light spectrums can be obtained. The resolution of the spectrometers can reach 2 nm across a wavelength range of 130 nm. The method in this work is CMOS compatible, enabling spectra retrieval for nanoscale radiators and can also be used to measure and retrieve the microscopic spectrum signal rapidly and timely without conventional scanning monochromator spectrometer.

Focus on photonics, spectroscopy, and spectrometry

Focus on photonics, spectroscopy, and spectrometry

Rapid time-resolved Circular Polarization Luminescence (CPL) emission spectroscopy

Circular polarisation luminescence (CPL) emission spectroscopy is a powerful tool for probing the fundamental chiroptical features of optically emissive chiral molecular systems. However, uptake of CPL spectroscopy has been impeded by the limitations of conventional scanning monochromator (SM) CPL spectrometers, which are costly to acquire and maintain, and typically require tens of minutes to acquire a typical CPL spectrum. Here, we demonstrate a design of CPL spectrometer which uses rapid readout solid state (SS) spectrometer detectors and a dual channel optical layout to acquire CPL spectra in as little as 10 milliseconds. We validate and demonstrate equivalent CPL measurement by measuring CPL spectra of two reference europium(III) complexes. Further, we demonstrate time-gated CPL acquisition, enabling long-lived CPL luminescence to be distinguished from short-lived emission of other fluorescent species. We anticipate that SS-CPL spectrometers will enable flexible, rapid, and relatively low-cost CPL spectroscopy for diverse applications.

Chemical Characterization of Wine Vinegars Belonging to the Vinagre de Montilla-Moriles Protected Designation of Origin, Using Near-Infrared Spectroscopy

Spanish wine vinegars belonging to Vinagre de Montilla-Moriles protected designation of origin (PDO) must satisfy some chemical characteristics. These characteristics are mainly responsible of their high and exceptional quality. This study assessed the potential of near-infrared spectroscopy (NIRS) as a non-destructive technology for characterizing wine vinegars belonging to this PDO. A total of 107 vinegars were used to predict major chemical quality parameters (volumic mass, reducing sugars, total acidity and pH) using a scanning monochromator (spectral range 400–2500 nm) with the spinning module, working in transflectance mode. The models developed showed values for the coefficient of regression for cross-validation between 0.95 and 0.99 for volumic mass, reducing sugars and total acidity. Therefore, the results confirm that NIRS technology combined with linear regression strategies such as the modified partial least squares (MPLS) regression can indeed respond to the needs of the vinegar cellars and help them to measure the commonest chemical quality parameters of wine vinegars belonging to Vinagre de Montilla-Moriles (PDO), especially in the case of vinegars with different sugar contents (dry, semi-sweet, sweet and balsamic). However, the number of vinegars as well as their variability should be increased in order to obtain more robust models.

Focus on photonics, spectroscopy, and spectrometry

Focus on photonics, spectroscopy, and spectrometry

Near-Infrared Broadband Cavity-Enhanced Spectroscopic Multigas Sensor Using a 1650 nm Light Emitting Diode.

A near-infrared broadband cavity-enhanced sensor system was demonstrated for the first time using an energy-efficient light emitting diode (LED) with a central emission wavelength at 1650 nm and a light power of ∼16 mW. A portable absorption gas cell was designed for realizing a compact and stable optical system for easy alignment. An ultrashort 8-cm-long cavity was fabricated consisting of two mirrors with a ∼99.35% reflectivity. Methane (CH4) measurement was performed employing two detection schemes, i.e., NIRQuest InGaAs spectrometer and scanning monochromator combined with phase-sensitive detection. Retrieval of CH4 concentration was performed using a least-squares fitting algorithm. Sensitivities (i.e., minimum detectable absorption coefficient) were achieved of 1.25 × 10-6 cm-1 for an averaging time of 45 s using the NIRQuest InGaAs spectrometer and 1.85 × 10-6 cm-1 for an averaging time of 8 min using the scanning spectrometer in combination with lock-in detection. Field monitoring of CH4 gas leakage was performed using the NIRQuest spectrometer. Multigas sensing of CH4 and acetylene (C2H2) was carried out simultaneously using the high-resolution scanning spectrometer. A linear response of the retrieved concentration level versus nominal value was observed with a large dynamic range, demonstrating the reliability of the compact LED-based near-infrared broadband cavity-enhanced absorption spectroscopy (NIR-IBBCEAS) for multigas sensing applications.

Focus on photonics, spectroscopy, and spectrometry

Femtosecond stimulated Raman spectrometerSection:ChooseTop of pageFemtosecond stimulated Ra... <<Flat-top beam shapersHigh-resolution imaging s...UV lasers for fluorescenc...Neutron imaging system MKS Instruments has launched its Newport femtosecond stimulated Raman spectrometer for scientific research. The nonlinear optical pump–probe instrument combines a narrowband Raman pump, an ultrafast broadband probe, and an ultrafast optical excitation “actinic” pulse. It allows for time-resolved vibrational spectroscopy with simultaneous high spectral and time resolution in the ground and excited states of molecules and yields spectra free from the interference of background fluorescence. Designed to work with amplified femtosecond lasers such as the Spectra-Physics Solstice Ace, the spectrometer can be reconfigured to perform transient absorption spectroscopy and to allow for selected changes such as using an external Raman pump source. MKS Instruments Inc, 2 Tech Dr, Ste 201, Andover, MA 01810, www.mksinst.com Flat-top beam shapersSection:ChooseTop of pageFemtosecond stimulated Ra...Flat-top beam shapers <<High-resolution imaging s...UV lasers for fluorescenc...Neutron imaging system Edmund Optics’ flat-top beam shapers convert collimated Gaussian input beams into collimated flat-top beams with a uniform density distribution and a flat phase front. Featuring an even intensity distribution that is stable over great distances, the converted beam is suitable for microscopy, holography, and system integration. With no internal focusing, flat-top beam shapers are appropriate for applications that require high-power lasers, such as material micromachining. The beam shapers are available with design wavelengths from 266 nm to 10 500 nm for common yttrium aluminum garnet, fiber, and carbon dioxide laser sources. Each operates over a specified wavelength range for laser tuning and can be used with multiple laser sources. Edmund Optics Inc, 101 E Gloucester Pike, Barrington, NJ 08007, www.edmundoptics.com High-resolution imaging spectrographSection:ChooseTop of pageFemtosecond stimulated Ra...Flat-top beam shapersHigh-resolution imaging s... <<UV lasers for fluorescenc...Neutron imaging system Princeton Instruments has added model HRS-500 to its SpectraPro HRS series. The 500 mm focal-length spectrograph and scanning monochromator has an astigmatism-corrected optical system for multichannel fiber applications. The company claims that its spectral deconvolution technology, ResXtreme, optimizes the instrument’s optical performance by improving by as much as 60% the spectral resolution, peak intensities, and consistency across the 2D focal plane. Two exit ports with a full 14 × 30 mm focal plane allow for mounting and operating two array detectors. Applications include Raman spectroscopy, photoluminescence, plasma diagnostics, absorption, and microspectroscopy. Princeton Instruments, 3660 Quakerbridge Rd, Trenton, NJ 08619, www.princetoninstruments.com UV lasers for fluorescence microspectroscopySection:ChooseTop of pageFemtosecond stimulated Ra...Flat-top beam shapersHigh-resolution imaging s...UV lasers for fluorescenc... <<Neutron imaging system Craic Technologies has expanded the capabilities of its 20/30 PV microspectrophotometers by adding deep-UV lasers as excitation sources for them to its laser offerings in the visible to near-IR range. The UV lasers can be used for fluorescence microspectroscopy and can be incorporated into the company’s new photoluminescence package. Both methods require intense light sources, and by exciting in the UV, more materials can be induced to emit photons via a luminescent process. The UV laser output is focused onto a microscopic sample area, and the emitted light is collected and measured by the 20/30 PV microspectrophotometer. The fluorescence or photoluminescence spectra are then analyzed. Craic Technologies Inc, 948 N Amelia Ave, San Dimas, CA 91773, www.microspectra.com Neutron imaging systemSection:ChooseTop of pageFemtosecond stimulated Ra...Flat-top beam shapersHigh-resolution imaging s...UV lasers for fluorescenc...Neutron imaging system << According to Photonis, its Neutronic [i] neutron imaging system provides high resolution and high detection efficiency compared with traditional scintillator-based neutron imaging systems. The system is suitable for physics research, neutron scattering, neutron tomography, and nondestructive testing applications. It uses both cold and thermal neutron imaging techniques to produce still and video images. To achieve neutron sensitivity, Neutronic [i] is equipped with a 100 × 100 mm microchannel plate from Photonis and NeuView technology from Nova Scientific. It houses a vacuum chamber, a high-voltage power supply, and a controller. The system provides short beam-time imaging to protect the items being imaged from damage and can deliver actionable images in under 2 h. Photonis USA Inc, 660 Main St, Sturbridge Business Park, PO Box 1159, Sturbridge, MA 01518, www.photonis.com © 2018 American Institute of Physics.

Near-infrared calibration transfer for undried whole maize plant between laboratory and on-site spectrometers

The analysis of the maize plant immediately after harvest is essential in order to check the composition and maturity of the plant to optimise the quality of silage. NIRS calibrations were carried out on chopped maize using three spectrophotometers: a laboratory instrument (FOSS NIRSystems 5000 scanning monochromator, FOSS, Silver Spring, MD) and two versions of new-generation portable instruments (poliSPECNIR, PL1 and PL2). The aim was to verify the quality of the transfer of the calibration curves between FOSS, PL1 and PL2 and between PL1 and PL2, obtained by three methods of spectra processing: pre-processing, piecewise direct standardisation (PDS) and direct standardisation (DS). Seventy-six samples of chopped whole maize plant were scanned with the three instruments and were analysed by wet chemistry for dry matter (DM), ash, crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), starch and total sugars, to develop calibration equations. Two more datasets of 15 samples each were used for the standardisation of equations and validation. The calibration transfer obtained, according to the values of R2, standard error of prediction and bias, can be considered satisfactory (0.72 > R2 <0.97) for DM, ash and NDF for both poliSPECNIR, while CP and ADF have shown a good accuracy of prediction (0.78 > R2 <0.82) with PL2. Using FOSS as a master instrument, the choice of method of standardisation varies depending on the slave instrument even though the best results are obtained using PDS with PL2. The most accurate predictions are reached using PDS even when PL1 is the master.

Application of fecal near-infrared reflectance spectroscopy profiling for the prediction of diet nutritional characteristics and voluntary intake in beef cattle.

The objective of this study was to evaluate the use of fecal near-infrared reflectance spectroscopy (NIRS) profiling to predict diet nutritional characteristics and voluntary DMI in beef cattle. Fecal samples were collected for growing cattle across 11 experiments in which individual animal performance and DMI was measured. Dried and ground fecal composite samples collected from each animal were subjected to fecal NIRS analysis by a Foss NIRS 6500 scanning monochromator (Foss, Eden Prairie, MN) at the Grazingland Animal Nutrition Laboratory (Temple, TX). Fecal spectra were then used to develop equations to predict diet composition (trials 1 to 11; = 408), digestibility (trials 1 to 5; = 155), and DMI (trials 1 to 11; = 408). Coefficients of determination for calibration () and cross-validation () for prediction of diet nutritional characteristics were lower for NDF ( = 0.85; = 0.82) than for CP ( = 0.90; = 0.88). For the prediction of DMI, and ranged from 0.69 and 0.67 for the prediction of trial-average DMI to 0.76 and 0.73 for the prediction of fecal-collection-period DMI. While the and obtained for the prediction of DMI were lower than those obtained for the prediction of diet composition or digestibility, fecal NIRS prediction equations for DMI were successful in predicting the mean DMI of groups, as no differences were found for the prediction of fecal-collection-period DMI (Diff. = 1.10; = 0.72) or trial DMI (Diff. = -0.47; = 0.86).

Evaluation of botanical and chemical composition of sheep diet by using faecal near infrared spectroscopy

The aim of this study was to use near infrared reflectance spectroscopy (NIRS) to directly predict the chemical composition and forage content of diets consumed by ewes from the analysis of their faeces. Twenty four ewes (46±3kg BW) placed in individual cages were used. Each animal was randomly allocated to four diets fed in four successive 28-days periods, so that a total of 16 diets were fed (six ewes per diet). Diets were designed to have different contents of neutral detergent fibre and crude protein. Daily rations of 800g (as-fed) were formulated with alfalfa hay (0–1000g/kg) or cereal straw (0–800g/kg) as forage base, different mixtures of maize, peas and lupins, offered as whole grains, and pelleted sunflower meal. Faeces samples were collected at the end of each feeding period, directly from the rectum. A total of 96 faeces samples were dried and ground. The samples were scanned in small ring cups in a FOSS-NIRSystems 6500 SY-II scanning monochromator. Faecal Modified Partial Least Squares calibration equations, selected in terms of standard error of cross validation (SECV) and coefficient of determination (r2), showed good predictive values for the prediction of dietary botanical ingredients (g/kg) alfalfa (41.9 and 0.98), cereal straw (48.6 and 0.97), maize (89.1 and 0.86), and forage (67.4 and 0.90) or concentrate (67.5 and 0.90) respectively, and also for chemical composition of fed diets (g/kg DM): ash (5.2 and 0.93), crude protein (9.6 and 0.89), ether extract (2.9 and 0.80), neutral detergent fibre (34.5 and 0.95) and non-fibre carbohydrates (38.7 and 0.94), respectively. Lower predictive capacity was obtained for peas (78.0 and 0.43), lupins (37.0 and 0.84) and sunflower meal (6.7 and 0.99), probably due to the limited variability of these ingredients in the diets. These results support the viability of faecal NIRS as a fast and reliable analytical method which allows to accurately predict the botanical composition, proportions of forage ingredients and chemical composition of diets consumed by ewes having free access to a variety of feed ingredients. Future works should be focused both to increase the variability of the diet ingredients and also to validate the models with external samples.

Application of visible/near-infrared reflectance spectroscopy for predicting internal and external quality in pepper.

The characterization of internal (°Brix, pH, malic acid, total phenolic compounds, ascorbic acid and total carotenoid content) and external (color, firmness and pericarp wall thickness) pepper quality is necessary to better understand its possible applications and increase consumer awareness of its benefits. The main aim of this work was to examine the feasibility of using visible/near-infrared reflectance spectroscopy (VIS-NIRS) to predict quality parameters in different pepper types. Commercially available spectrophotometers were evaluated for this purpose: a Polychromix Phazir spectrometer for intact raw pepper, and a scanning monochromator for freeze-dried pepper. The RPD values (ratio of the standard deviation of the reference data to the standard error of prediction) obtained from the external validation exceeded a value of 3 for chlorophyll a and total carotenoid content; values ranging between 2.5 < RPD < 3 for total phenolic compounds; between 1.5 < RPD <2.5 for °Brix, pH, color parameters a* and h* and chlorophyll b; and RPD values below 1.5 for fruit firmness, pericarp wall thickness, color parameters C*, b* and L*, vitamin C and malic acid content. The present work has led to the development of multi-type calibrations for pepper quality parameters in intact and freeze-dried peppers. The majority of NIRS equations obtained were suitable for screening purposes in pepper breeding programs. Components such as pigments (xanthophyll, carotenes and chlorophyll), glucides, lipids, cellulose and water were used by modified partial least-squares regression for modeling the predicting equations. © 2015 Society of Chemical Industry.

Quick scanning monochromator for millisecond in situ and in operando X-ray absorption spectroscopy.

The design and capabilities of a novel Quick scanning Extended X-ray Absorption Fine Structure (QEXAFS) monochromator are presented. The oscillatory movement of the crystal stage is realized by means of a unique open-loop driving scheme operating a direct drive torque motor. The entire drive mechanics are installed inside of a goniometer located on the atmospheric side of the vacuum chamber. This design allows remote adjustment of the oscillation frequency and spectral range, giving complete control of QEXAFS measurements. It also features a real step-scanning mode, which operates without a control loop to prevent induced vibrations. Equipped with Si(111) and Si(311) crystals on a single stage, it facilitates an energy range from 4.0 keV to 43 keV. Extended X-ray absorption fine structure spectra up to k = 14.4 Å(-1) have been acquired within 17 ms and X-ray absorption near edge structure spectra covering more than 200 eV within 10 ms. The achieved data quality is excellent as shown by the presented measurements.

Determination of oil content in whole corn (Zea mays L.) seeds by means of near infrared reflectance spectroscopy

The objective of this study was to evaluate the ability of near infrared reflectance (NIR) spectroscopy to determine oil content in whole corn (Zea mays L.) samples sourced from a breeding program. Kernel samples were analysed in reflectance in the VIS and NIR regions (400–2500nm) at 2nm intervals using a scanning monochromator. Samples were scanned in a circular cell cup and reflectance data were stored as logarithm of the reciprocal reflectance (log1/R). Samples were not rotated when spectra collection was made. The coefficients of determination (R2) and the standard error of cross validation (SECV) obtained for the prediction of oil content in the calibration set were 0.90% and 0.17%, respectively. The residual predictive deviation (RPD=SD/SECV) value obtained was 2.3, indicating that these calibrations can be used for qualitative determination of oil content (e.g. low, medium and high) or preliminary screening in whole corn.

Emissivity of Lanthanum Hexaboride Thermionic Electron Gun Cathode

The emissivity of the thermionic electron gun cathode material lanthanum hexaboride (LaB $$_6$$ ) at an operating temperature of 1622 K has been measured for wavelengths from 550 nm to 2400 nm. The emissivity is calculated from scanning monochromator spectral measurements calibrated with a tungsten lamp and the published emissivity of 0.82 at 1600 K for LaB $$_6$$ at 650 nm. The results show a higher emissivity at shorter wavelengths (up to 0.86 at 729 nm) and a lower emissivity in the near-IR to mid-IR (down to 0.41 at 2146 nm). These measurements were motivated by the need to make fast, accurate optical measurements of the temperature of the LaB $$_6$$ cathode in our thermionic microwave gun, and to select the wavelength most readily absorbed by the cathode for manipulation of its surface temperature as a means of counteracting back-bombardment heating.