Optical Breast Spectroscopy (OBS) has been shown to predict mammographic breast density, a strong breast cancer risk factor. OBS is a low‐cost technique applicable at any age. OBS information may be useful for personalizing breast cancer screening programs based on risk to improve consensus on and adherence to screening guidelines. To facilitate the use of OBS in population‐wide studies, a research prototype OBS device was modified to make it portable and cheaper and to require less operator interaction. Two major changes were made: (1) the broadband light source was replaced with a laser module with 13 individual wavelengths turned on sequentially, enabling the use of photodiode detectors instead of a spectrometer, and (2) the light sources and detectors were placed in fixed positions within 4 sizes of cup, eliminating the need for placement by the operator. Wavelengths were selected using data from two previous studies. The reduction in spectral content did not significantly reduce the ability to distinguish between different risk groups. Positions for the light sources and detectors were chosen based on Monte Carlo simulations to match the optically interrogated volumes of the original device. Two light sources and six detectors per cup were used in the final design.
A 12‐laser‐wavelength, fixed source‐detector position, cup‐based optical breast spectroscopy (OBS) device was developed for use in large‐scale, multicenter trials as a mammographic breast density (MBD) quantification and breast cancer (BC) risk prescreening tool. In this study, the device was evaluated in comparison with a spectrometer‐based device used in previous studies. The devices were compared on their ability to predict mammographic percent density (MPD) and to identify women with high MBD from optical spectra. OBS measurements were made on 60 women, (age 29‐73), using both devices. Recent mammograms were collected for all women and MPD quantified from the mammograms. Principal components (PCs) analysis was performed on both sets of OBS spectra, and multivariate logistic regression analysis of the resulting PC scores was used to identify women with high MBD. Both devices are able to identify high MBD with very high sensitivity and specificity. Partial least‐squares regression of the spectra was used to predict MPD. Both devices show a strong correlation between OBS‐predicted MPD and MPD read from mammograms, however, the correlation is stronger for the continuous‐spectrum device (r = 0.74, P = .001) than for the 12‐wavelength device (r = 0.62, P = .004). Improvements to the cup‐based device to reduce detector saturation should improve the prediction of MPD from the spectra. 相似文献
Adjusting fertiliser applications to within-field variations in nitrogen (N) mineralisation during the growing season can
increase yields, improve crop quality, reduce costs and decrease nutrient losses to the environment. Predicting such variations
at a reasonable cost is therefore important. In a 3-year study, Near Infrared Reflectance (NIR) spectroscopy was compared
with soil organic matter (SOM) and clay content as predictors of plant N uptake using cross-validated PLS (Partial Least Squares)
regression models. Plant N uptake was measured as total nitrogen in aboveground plant parts at harvest, in plots without N
fertilisation within three different fields in southern Sweden. NIR spectroscopy and combined clay and SOM content resulted
in equally good estimations of plant N uptake in fields with large variation in SOM content. Cross-validated NIR calibrations
for plant N uptake within fields for separate years resulted in r2 values of 0.75–0.85 and average cross-validation errors of 11–16 kg N ha−1 for two fields (1 year excluded at one field because of farmyard manure application). No significant improvements were seen
when NIR-spectra, clay and SOM were included in the same model, suggesting that the additional predictive capacity of NIR
over SOM relates to soil texture variations. NIR calibrations also performed poorly in one field where plant N uptake could
not be explained by SOM or clay content. Predictions within fields between years produced r2 values of 0.56–0.89 and prediction errors of 12–26 kg N ha−1 for one field. These results confirm that N uptake prediction accuracy can be improved by using NIR spectroscopy in fields
with large SOM variations. However, good estimations could not be made between fields, indicating difficulties in creating
more general calibration models for large geographical areas. 相似文献
A method that provides maps of absolute concentrations of oxygenated and deoxygenated myoglobin (Mb), its oxygenation, and its near-infrared (NIR) optical pathlength in cardiac tissue was developed. These parameters are available simultaneously. The method is based on NIR diffuse reflectance spectroscopic imaging and specific processing of the NIR images, which included a first derivative of the diffuse reflectance spectrum. Mb oxygenation, total Mb concentration, and NIR light pathlength were found to be in the range of 92%, 0.3 mM, and 12.5 mm, respectively, in beating isolated buffer-perfused and arrested pig hearts. The charge-coupled device camera enables sub-millimeter spatial resolution and spectroscopic imaging in 1.5 to 2.0 min. The technique is noninvasive and nondestructive. The equipment has no mechanical contact with the tissue of interest, leaving it undisturbed. 相似文献
Digestibility is a key parameter in the evaluation of feeds; however, the measurements on animals require heavy experimental trials, which are hardly feasible when large numbers of determinations are required – for example, in genetic studies. This experiment aimed at investigating the possibility to predict digestibility from NIRS spectra measured on faeces. A total of 196 samples were available from a digestibility experiment investigating the effects of age and genetic background of Large White pigs fed the same diet, rich in fibre (NDF=21.4% DM). Digestibility of dry matter (dDM), organic matter (dOM), nitrogen content (dN), energy (dE) and apparent digestible energy content (ADE) were calculated, as well as total N content of faeces (N). The faeces samples were submitted to reflectance NIRS analysis after freeze-drying and grinding. Calibration errors and validation errors were, respectively, 0.08 and 0.13% DM for total N in faeces, 0.97% and 1.08% for dDM, 0.79% and 1.04% for dOM, 1.04% and 1.47% for dN, 0.87% and 1.12% for dE and 167 and 213 kJ/kg DM for ADE. These results indicate that NIRS can account for digestibility differences due to animal factors, with an acceptable accuracy. NIRS appears to be a promising tool for large-scale evaluations of digestibility. It could also be used for the study of digestibility of different feeds, after appropriate calibration based on a wide range of feed types. 相似文献
Histone deacetylases (HDACs) have been found to be biomarkers of cancers and the corresponding inhibitors have attracted much attention these years. Herein we reported a near-infrared fluorescent HDAC inhibitor based on vorinostat (SAHA) and a NIR fluorophore. This newly designed inhibitor showed similar inhibitory activity to SAHA against three HDAC isoforms (HDAC1, 3, 6). The western blot assay showed significant difference in compared with the negative group. When used as probe for further kinematic imaging, Probe 1 showed enhanced retention in tumor cells and the potential of HDAC inhibitors in drug delivery was firstly brought out. The cytotoxicity assay showed Probe 1 had some anti-proliferation activities with corresponding IC50 values of 9.20 ± 0.96 μM on Hela cells and 5.91 ± 0.57 μM on MDA-MB-231 cells. These results indicated that Probe 1 could be used as a potential NIR fluorescent in the study of HDAC inhibitors and lead compound for the development of visible drugs. 相似文献
Dye molecules with various fluorescent wavelengths are widely used for diagnostic and optical imaging applications. Accordingly, there is a constant demand for fluorogenic dyes with new properties. We have recently developed a novel strategy for the design of long-wavelength fluorescent dyes with a turn-ON option. The design is based on a donor-two-acceptor π-electron system that can undergo an internal charge transfer to form a new fluorochrome with an extended π-conjugated system. Here, we describe a series of such dyes based on two novel latent donors, naphthol and hydroxycoumarin. One of the dyes has showed excellent near-infrared fluorescent characteristics and specifically was demonstrated as a mitochondrial imaging reagent in live cells. This unique strategy for fluorogenic dye design has opened new doors for further near-infrared fluorescence probe discovery. 相似文献
The purpose of this research was to investigate the variability of the roller compaction process while monitoring in-line
with near-infrared (NIR) spectroscopy. In this paper, a pragmatic method in determining this variability of in-line NIR monitoring
roller compaction process was developed and the variability limits were established. Fast Fourier Transform (FFT) analysis
was used to study the source of the systematic fluctuations of the NIR spectra. An off-line variability analysis method was
developed as well to simulate the in-line monitoring process in order to determine the variability limits of the roller compaction
process. For this study, a binary formulation was prepared composed of acetaminophen and microcrystalline cellulose. Different
roller compaction parameters such as roll speed and feeding rates were investigated to understand the variability of the process.
The best-fit line slope of NIR spectra exhibited frequency dependence only on the roll speed regardless of the feeding rates.
The eccentricity of the rolling motion of rollers was identified as the major source of variability and correlated with the
fluctuations of the slopes of NIR spectra. The off-line static and dynamic analyses of the compacts defined two different
variability of the roller compaction; the variability limits were established. These findings were proved critical in the
optimization of the experimental setup of the roller compaction process by minimizing the variability of NIR in-line monitoring. 相似文献
The methods used to quantify total alginate in brown algal tissue are time-consuming and may also be misleading, so faster
and simpler methods for measuring alginate content would be beneficial in a variety of applications. This study reports on
the use of near infra-red (NIR) analysis to monitor the alginate content of Laminaria hyperborea stipe during biodegradation.
NIR reflectance spectra were recorded for 78 different freeze-dried samples of its stipe. The samples were collected during
several biological degradation experiments and the total alginate content varied from 2.2 to 40.8% Na-alginate (w/w), determined
by established methods based on ion exchange. Data analysis was performed using multivariate calibration methods in order
to relate the spectral data to the alginate content. PLS2 analysis revealed some dependence on material type, probably reflecting
differences in polyphenol content. In the end, a PLS1 model with 9 components was selected. The calculated model was validated
both with internal data and with an external test set. Internal full cross validation explained 96.6% of the variance in alginate
content. The external validation showed that the PLS1 model was able to predict the alginate concentration with a root mean
square prediction accuracy of 2.1%.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
Lippia species are widely used as traditional remedies by many South African communities. The identification of Lippia spp. indigenous to South Africa is currently based on the morphology and geographical origin of the specimen. However, morphological similarities are evident and due to sympatric distributions, different species may co-occur in the same natural environment, thereby presenting difficulties in the taxonomic delimitation of these taxa. In this paper, gas chromatography–mass spectrometry (GC–MS) and vibrational spectroscopic analyses were used to investigate the chemotaxonomic differentiation of four Lippia species (L. javanica, L. scaberrima, L. rehmannii and L. wilmsii), based on the essential oil composition. The results demonstrate that multivariate classification of chromatographic data enabled separation of Lippia oils into three distinct clusters representing L. scaberrima, L. rehmannii and L. javanica. With the aid of chemometric algorithms, it was also possible to use both mid infrared (MIR) and near infrared (NIR) spectroscopy for a clear distinction of the Lippia spp., with results comparable to those obtained by GC–MS. Orthogonal projections to latent structures (OPLS) presented a better classification algorithm than principal component analysis (PCA), in both GC–MS and spectroscopy analyses. Chemical variations within the Lippia spp. complex were evident, particularly for L. javanica and L. scaberrima, which exhibited significant intra-species variation. 相似文献
AbstractThe exposure and risk evaluation process in Bulgaria concerning non-ionizing radiation health and safety started in the early 1970s. Then, the first research laboratory “Electromagnetic fields in the working environment” was founded in the framework of the Centre of Hygiene, belonging to the Medical Academy, Sofia. The main activities were connected with developing legislation, new equipment for measurement of electromagnetic fields, new methods for measurement and exposure assessment, in vivo and human studies for developing methods, studying the effect of non-ionizing radiation on human body, developing exposure limits. Most of the occupations as metal industry, plastic welding, energetics, physiotherapy, broadcasting, telephone stations, computer industry, etc., have been covered by epidemiological investigations and risk evaluation. In 1986, the ANSI standard for safe use of lasers has been implemented as national legislation that gave the start for studies in the field of risk assessment concerning the use of lasers in industry and medicine. The environmental exposure studies started in 1991 following the very fast implementation of the telecommunication technologies. Now, funds for research are very insignificant, and studies in the field of risk assessment are very few. Nevertheless, Bulgaria has been an active member of the WHO International EMF Project, since 1997, and that gives good opportunity for collaboration with other Member states, and for implementation of new approach in the EMF policy for workers and people’s protection against non-ionizing radiation exposure. 相似文献
This paper investigates near infra-red spectroscopy (NIRS) as an indirect and rapid method to assess the biochemical methane potential (BMP) of meadow grasses. Additionally analytical methods usually associated with forage analysis, namely, the neutral detergent fibre assay (NDF), and the in-vitro organic matter digestibility assay (IVOMD), were also tested on the meadow grass samples and the applicability of the models in predicting the BMP was studied. Based on these, regression models were obtained using the partial least squares (PLS) method. Various data pre-treatments were also applied to improve the models. Compared to the models based on the NDF and IVOMD predictions of BMP, the model based on the NIRS prediction of BMP gave the best results. This model, with data pre-processed by the mean normalisation method, had an R2 value of 0.69, a root mean square error of prediction (RMSEP) of 37.4 and a residual prediction deviation (RPD) of 1.75. 相似文献
More efficient utilization of phosphorus by wheat plants is needed to extend the useful life of the phosphate reserves in the world, to reduce the cost of producing crops, and to improve the value of the grain and the straw produced. In this paper definitions of efficient use of phosphorus by wheat are reviewed, genotypic variation in phosphorus efficiency is reported, some consequences of breeding for greater efficiency are discussed, and ways to select more efficient genotypes are suggested. 相似文献
Since consumers are showing increased interest in the origin and method of production of their food, it is important to be able to authenticate dietary history of animals by rapid and robust methods used in the ruminant products. Promising breakthroughs have been made in the use of spectroscopic methods on fat to discriminate pasture-fed and concentrate-fed lambs. However, questions remained on their discriminatory ability in more complex feeding conditions, such as concentrate-finishing after pasture-feeding. We compared the ability of visible reflectance spectroscopy (Vis RS, wavelength range: 400 to 700 nm) with that of visible-near-infrared reflectance spectroscopy (Vis-NIR RS, wavelength range: 400 to 2500 nm) to differentiate between carcasses of lambs reared with three feeding regimes, using partial least square discriminant analysis (PLS-DA) as a classification method. The sample set comprised perirenal fat of Romane male lambs fattened at pasture (P, n=69), stall-fattened indoors on commercial concentrate and straw (S, n=55) and finished indoors with concentrate and straw for 28 days after pasture-feeding (PS, n=65). The overall correct classification rate was better for Vis-NIR RS than for Vis RS (99.0% v. 95.1%, P<0.05). Vis-NIR RS allowed a correct classification rate of 98.6%, 100.0% and 98.5% for P, S and PS lambs, respectively, whereas Vis RS allowed a correct classification rate of 98.6%, 94.5% and 92.3% for P, S and PS lambs, respectively. This study suggests the likely implication of molecules absorbing light in the non-visible part of the Vis-NIR spectra (possibly fatty acids), together with carotenoid and haem pigments, in the discrimination of the three feeding regimes. 相似文献
Near-infrared (NIR) spectroscopic analysis of noncrystalline polyols and saccharides (e.g., glycerol, sorbitol, maltitol,
glucose, sucrose, maltose) was performed at different temperatures (30–80°C) to elucidate the effect of glass transition on
molecular interaction. Transmission NIR spectra (4,000–12,000 cm−1) of the liquids and cooled-melt amorphous solids showed broad absorption bands that indicate random configuration of molecules.
Heating of the samples decreased an intermolecular hydrogen-bonding OH vibration band intensity (6,200–6,500 cm−1) with a concomitant increase in a free and intramolecular hydrogen-bonding OH group band (6,600–7,100 cm−1). Large reduction of the intermolecular hydrogen-bonding band intensity at temperatures above the glass transition (Tg) of the individual solids should explain the higher molecular mobility and lower viscosity in the rubber state. Mixing of
the polyols with a high Tg saccharide (maltose) or an inorganic salt (sodium tetraborate) shifted both the glass transition and the inflection point
of the hydrogen-bonding band intensity to higher temperatures. The implications of these results for pharmaceutical formulation
design and process monitoring (PAT) are discussed. 相似文献