Evaluation of Three Approaches for Real-Time Monitoring of Roller Compaction with Near-Infrared Spectroscopy

Three different approaches have been evaluated for monitoring ribbon density through real-time near-infrared spectroscopy measurements. The roll compactor was operated to produce microcrystalline cellulose (MCC) ribbons of varying densities. The first approach used the slope of the spectra which showed a variation through the ribbon that could be attributed to density. A second qualitative approach was also developed with a principal component analysis (PCA) model with spectra taken in-line during the production of ribbons in an ideal roll pressure range. The PCA (i.e., real-time) density scans show that the model was able to qualitatively capture the density responses resulting from variation in process parameters. The third approach involved multivariate partial least squares (PLS) calibration models developed at wavelength regions of 1,120–1,310 and 1,305–2,205 nm. Also, various PLS models were developed using three reference methods: caliper, pycnometer, and in-line laser. The third approach shows a quantitative difference between the model-predicted and the measured densities. Models developed at high-wavelength region showed highest accuracy compared with models at low-wavelength region. All the PLS models showed a high accuracy along the spectra collected throughout the production of the ribbons. The three methods showed applicability to process control monitoring by describing the changes in density during in-line sampling.     

Quality-by-Design III: Application of Near-Infrared Spectroscopy to Monitor Roller Compaction In-process and Product Quality Attributes of Immediate Release Tablets

The objective of this study is to use near-infrared spectroscopy (NIRS) coupled with multivariate chemometric models to monitor granule and tablet quality attributes in the formulation development and manufacturing of ciprofloxacin hydrochloride (CIP) immediate release tablets. Critical roller compaction process parameters, compression force (CF_t), and formulation variables identified from our earlier studies were evaluated in more detail. Multivariate principal component analysis (PCA) and partial least square (PLS) models were developed during the development stage and used as a control tool to predict the quality of granules and tablets. Validated models were used to monitor and control batches manufactured at different sites to assess their robustness to change. The results showed that roll pressure (RP) and CF_t played a critical role in the quality of the granules and the finished product within the range tested. Replacing binder source did not statistically influence the quality attributes of the granules and tablets. However, lubricant type has significantly impacted the granule size. Blend uniformity, crushing force, disintegration time during the manufacturing was predicted using validated PLS regression models with acceptable standard error of prediction (SEP) values, whereas the models resulted in higher SEP for batches obtained from different manufacturing site. From this study, we were able to identify critical factors which could impact the quality attributes of the CIP IR tablets. In summary, we demonstrated the ability of near-infrared spectroscopy coupled with chemometrics as a powerful tool to monitor critical quality attributes (CQA) identified during formulation development.KEY WORDS: chemometrics, crushing force, disintegration, near-infrared spectroscopy, partial least square, principal component analysis, quality by design, roller compaction     

红外光谱技术在生物过程监测中的应用

在线监测化学组分的浓度对许多生物过程都是十分必要的。然而,探头需耐高温灭菌的要求和生物体系自身的复杂性给许多分析技术的在线监测带来了困难。近几年,随仪器和数据处理技术的迅速发展,应用红外光谱技术对生物过程的原位或在线监测日益广泛。本文对红外过程分析技术进行了较全面的综述,介绍了红外分析的原理、进展及在生物过程监测中的应用。     

Design of Experiments-Based Monitoring of Critical Quality Attributes for the Spray-Drying Process of Insulin by NIR Spectroscopy

Moisture content and aerodynamic particle size are critical quality attributes for spray-dried protein formulations. In this study, spray-dried insulin powders intended for pulmonary delivery were produced applying design of experiments methodology. Near infrared spectroscopy (NIR) in combination with preprocessing and multivariate analysis in the form of partial least squares projections to latent structures (PLS) were used to correlate the spectral data with moisture content and aerodynamic particle size measured by a time of flight principle. PLS models predicting the moisture content were based on the chemical information of the water molecules in the NIR spectrum. Models yielded prediction errors (RMSEP) between 0.39% and 0.48% with thermal gravimetric analysis used as reference method. The PLS models predicting the aerodynamic particle size were based on baseline offset in the NIR spectra and yielded prediction errors between 0.27 and 0.48 μm. The morphology of the spray-dried particles had a significant impact on the predictive ability of the models. Good predictive models could be obtained for spherical particles with a calibration error (RMSECV) of 0.22 μm, whereas wrinkled particles resulted in much less robust models with a Q² of 0.69. Based on the results in this study, NIR is a suitable tool for process analysis of the spray-drying process and for control of moisture content and particle size, in particular for smooth and spherical particles.KEY WORDS: moisture content, multivariate analysis, NIR, particle size, spray-drying     

近红外光谱法快速测定白芍中芍药苷含量

本研究旨在应用近红外光谱法建立一种白芍药材中芍药苷含量的快速测定方法。利用HPLC测定样品中芍药苷含量,并以其作为参考值,运用偏最小二乘法(PLS)建立芍药苷含量与近红外光谱之间的多元校正模型,对未知样品进行含量预测。结果表明,所建芍药苷定量分析模型的相关系数(R2)、内部交叉验证均方差(RMSECV)、校正均方差(RMSEC)分别为0.99395、0.33068、0.0563;经内部验证,模型的预测均方差(RMSEP)和平均回收率分别为0.0756和100.07%。该方法操作简便,无污染,结果准确可靠,可用于白芍中芍药苷含量的快速测定。     

Application of Quantitative Real-Time Polymerase Chain Reaction for Noninvasive Genetic Monitoring

ABSTRACT Noninvasive genetic monitoring of animal populations has become a widely used method in animal conservation and wildlife management due to its known advantages in sample availability of endangered or elusive species. A variety of methods have been suggested to overcome the difficulties of collecting reliable genetic data despite poor DNA quality and quantity of samples. We used quantitative real-time polymerase chain reaction (qPCR) to quantify DNA contents and preselect extracts suitable for microsatellite genotyping of noninvasive samples from 2 carnivore species, wolf (Canis lupus) and Eurasian otter (Lutra lutra). We tested 2 concentration thresholds for DNA extracts containing either 5 pg/μL or 25 pg/μL at minimum and evaluated the effect of excluding samples from genotyping falling below either of these DNA concentrations. Depending on species and threshold concentration applied, we reduced the genotyping effort by 21% to 47% and genotyping errors by 7% to 45%, yet we could still detect 82% to 99% of available genotypes. Thus, qPCR may potentially reduce genotyping effort and enhance data reliability in noninvasive genetic studies. Genetic laboratories working on noninvasive population genetic studies could transfer this approach to other species, streamline genetic analyses and, thus, more efficiently provide wildlife managers with reliable genetic data of wild populations.     

基于NIRS法快速检测荞麦蛋白质与淀粉含量的研究

为建立近红外光谱技术测定荞麦蛋白质与淀粉含量的方法,本研究以217份荞麦样品为试验材料,采用最小二乘回归预测和交叉验证构建近红外预测模型。分析表明:前处理采用多元散射校正法(MSC),维数(Rank)分别为5和5,光谱区间6803.9~6094.2/cm所建立的荞麦蛋白质与淀粉含量模型的预测效果较好,其决定系数(R~2)分别为0.9481和0.9167,交叉验证均方根(RMSECV)分别为0.68和2.08,相对分析误差(RPD)分别为4.39和3.46,均大于3.0,外部验证相关系数均大于0.96。本试验所建立的蛋白质与淀粉含量近红外预测模型具有较高的准确度和稳健性,可用于荞麦品质的快速测定。     

Rapid Biomass Quality Determination of Corn Stover Using Near-Infrared Reflectance Spectroscopy

Near-infrared reflectance spectroscopy (NIRS) has been used extensively in the forage industry for rapid measurement of forage constituents and could be useful for determining quality of biomass feedstocks at the point of delivery. In previous work, we developed an assay that partitions feedstock carbohydrates based on their availability to be converted to fermentable sugars, including non-structural carbohydrates (C _N), biochemically available carbohydrates (C _B) with an associated first-order availability rate constant (k _B), and unavailable carbohydrates (C _U ). Additional quality parameters measured included neutral detergent lignin (NDL), total available carbohydrates (C _A), and total carbohydrates (C _T). We evaluated the variability of biomass quality parameters in a set of corn stover samples and developed calibration equations for determining parameter values using NIRS. Fifty-two corn stover samples harvested in Iowa and Wisconsin in 2005 and 2006 were analyzed using a high-throughput assay for determining feedstock quality for biochemical conversion. Non-structural carbohydrates ranged from 84 to 155?g?kg^?1 dry matter (DM); C _B ranged from 354 to 557?g?kg^?1 DM; k _B ranged from 0.199 to 0.330?h^?1; C _A ranged from 463 to 699?g?kg^?1 DM, and NDL ranged from 32 to 74?g?kg^?1 DM. Significant differences (P?<?0.0001) among samples were observed for all parameters, except k _B. Near-infrared reflectance spectroscopy calibration equations were developed for C _N, C _B, C _A, C _U , C _T, and NDL. It was not possible to generate a meaningful calibration equation for k _B. There is significant variability within the corn stover population for several key quality-related carbohydrate and lignin constituents which can be predicted reliably using NIRS.     

利用近红外光谱对杂种松及其亲本的鉴别分析

为了在林木育种和良种推广过程中对杂种松的真实性进行简单、快速鉴别,本研究以我国南方培育推广的2个杂种松及其3个亲本树种为研究材料,通过近红外光谱仪扫描各树种的针叶来采集数据,最后采用PLS-DA（偏最小回归-判别分析）方法建模对杂种松及其亲本进行鉴别。研究结果显示：本研究中PLS-DA方法对杂种松具有较高的判别能力,可以较好地将研究的2个杂种松及其3个亲本树种区别开来。因此,近红外光谱结合PLS-DA判别分析方法可以用来分析鉴别松树中的杂种和纯种,相对于同工酶和分子标记这些种质鉴别方法,近红外光谱技术具有简便、快捷等优点,值得在林木种质判别分析中进一步研究利用。     

Real-Time Imaging of DNA Damage in Yeast Cells Using Ultra-Short Near-Infrared Pulsed Laser Irradiation

Analysis of accumulation of repair and checkpoint proteins at repair sites in yeast nuclei has conventionally used chemical agents, ionizing radiation or induction of endonucleases to inflict localized damage. In addition to these methods, similar studies in mammalian cells have used laser irradiation, which has the advantage that damage is inflicted at a specific nuclear region and at a precise time, and this allows accurate kinetic analysis of protein accumulation at DNA damage sites. We show here that it is feasible to use short pulses of near-infrared laser irradiation to inflict DNA damage in subnuclear regions of yeast nuclei by multiphoton absorption. In conjunction with use of fluorescently-tagged proteins, this allows quantitative analysis of protein accumulation at damage sites within seconds of damage induction. PCNA accumulated at damage sites rapidly, such that maximum accumulation was seen approximately 50 s after damage, then levels declined linearly over 200–1000 s after irradiation. RPA accumulated with slower kinetics such that hardly any accumulation was detected within 60 s of irradiation, and levels subsequently increased linearly over the next 900 s, after which levels were approximately constant (up to ca. 2700 s) at the damage site. This approach complements existing methodologies to allow analysis of key damage sensors and chromatin modification changes occurring within seconds of damage inception.     

Neuronal Correlates of Cognitive Control during Gaming Revealed by Near-Infrared Spectroscopy

In everyday life we quickly build and maintain associations between stimuli and behavioral responses. This is governed by rules of varying complexity and past studies have identified an underlying fronto-parietal network involved in cognitive control processes. However, there is only limited knowledge about the neuronal activations during more natural settings like game playing. We thus assessed whether near-infrared spectroscopy recordings can reflect different demands on cognitive control during a simple game playing task. Sixteen healthy participants had to catch falling objects by pressing computer keys. These objects either fell randomly (RANDOM task), according to a known stimulus-response mapping applied by players (APPLY task) or according to a stimulus-response mapping that had to be learned (LEARN task). We found an increased change of oxygenated and deoxygenated hemoglobin during LEARN covering broad areas over right frontal, central and parietal cortex. Opposed to this, hemoglobin changes were less pronounced for RANDOM and APPLY. Along with the findings that fewer objects were caught during LEARN but stimulus-response mappings were successfully identified, we attribute the higher activations to an increased cognitive load when extracting an unknown mapping. This study therefore demonstrates a neuronal marker of cognitive control during gaming revealed by near-infrared spectroscopy recordings.     

NIR Spectroscopy Applications in the Development of a Compacted Multiparticulate System for Modified Release

The purpose of this study was to utilize near-infrared spectroscopy and chemical imaging to characterize extrusion-spheronized drug beads, lipid-based placebo beads, and modified release tablets prepared from blends of these beads. The tablet drug load (10.5–19.5 mg) of theophylline (2.25 mg increments) and cimetidine (3 mg increments) could easily be differentiated using univariate analyses. To evaluate other tablet attributes (i.e., compression force, crushing force, content uniformity), multivariate analyses were used. Partial least squares (PLS) models were used for prediction and principal component analysis (PCA) was used for classification. The PLS prediction models (R ² > 0.98) for content uniformity of uncoated compacted theophylline and cimetidine beads produced the most robust models. Content uniformity data for tablets with drug content ranging between 10.5 and 19.5 mg showed standard error of calibration (SEC), standard error of cross-validation, and standard error of prediction (SEP) values as 0.31, 0.43, and 0.37 mg, and 0.47, 0.59, and 0.49 mg, for theophylline and cimetidine, respectively, with SEP/SEC ratios less than 1.3. PCA could detect blend segregation during tableting for preparations using different ratios of uncoated cimetidine beads to placebo beads (20:80, 50:50, and 80:20). Using NIR chemical imaging, the 80:20 formulations showed the most pronounced blend segregation during the tableting process. Furthermore, imaging was capable of quantitating the cimetidine bead content among the different blend ratios. Segregation testing (ASTM D6940-04 method) indicated that blends of coated cimetidine beads and placebo beads (50:50 ratio) also tended to segregate.     

Real-Time Sensing of Cell Morphology by Infrared Waveguide Spectroscopy

We demonstrate that a live epithelial cell monolayer can act as a planar waveguide. Our infrared reflectivity measurements show that highly differentiated simple epithelial cells, which maintain tight intercellular connectivity, support efficient waveguiding of the infrared light in the spectral region of 1.4–2.5 µm and 3.5–4 µm. The wavelength and the magnitude of the waveguide mode resonances disclose quantitative dynamic information on cell height and cell-cell connectivity. To demonstrate this we show two experiments. In the first one we trace in real-time the kinetics of the disruption of cell-cell contacts induced by calcium depletion. In the second one we show that cell treatment with the PI3-kinase inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 results in a progressive decrease in cell height without affecting intercellular connectivity. Our data suggest that infrared waveguide spectroscopy can be used as a novel bio-sensing approach for studying the morphology of epithelial cell sheets in real-time, label-free manner and with high spatial-temporal resolution.     

利用近红外光谱技术快速检测大豆氨基酸含量

为探索近红外光谱技术在大豆氨基酸测试中的应用,寻找一种快速的检测方法,以167份大豆[Glycine max(L.)Merr.]种子为材料,采用傅里叶变换近红外光谱技术(FT-NIRS)对经高效液相色谱法(HPLC)分析的18种氨基酸含量进行模拟.结果显示:天冬氨酸(R2cv=0.85)、谷氨酸(R2cv=0.86)、丝氨酸(R2cv=0.82)、甘氨酸(R2cv=0.89)、酪氨酸(R2cv=0.83)、苯丙氨酸(R2cv=0.78)、异亮氨酸(R2cv=0.86)和色氨酸(R2cv=0.81)及15种氨基酸总和(R2cv=0.82)可利用FT-NIRS准确预测;苏氨酸、精氨酸、丙氨酸、缬氨酸、亮氨酸和胱氨酸检测模型有一定的参考价值,可用来进行相对含量的估测;而对组氨酸、赖氨酸、脯氨酸和蛋氨酸的预测不准确.本研究进一步证明,利用FT-NIRS技术预测大豆主要氨基酸组分是稳定可行的.     

In Situ Measurement of Some Soil Properties in Paddy Soil Using Visible and Near-Infrared Spectroscopy

In situ measurements with visible and near-infrared spectroscopy (vis-NIR) provide an efficient way for acquiring soil information of paddy soils in the short time gap between the harvest and following rotation. The aim of this study was to evaluate its feasibility to predict a series of soil properties including organic matter (OM), organic carbon (OC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), available potassium (AK) and pH of paddy soils in Zhejiang province, China. Firstly, the linear partial least squares regression (PLSR) was performed on the in situ spectra and the predictions were compared to those with laboratory-based recorded spectra. Then, the non-linear least-square support vector machine (LS-SVM) algorithm was carried out aiming to extract more useful information from the in situ spectra and improve predictions. Results show that in terms of OC, OM, TN, AN and pH, (i) the predictions were worse using in situ spectra compared to laboratory-based spectra with PLSR algorithm (ii) the prediction accuracy using LS-SVM (R²>0.75, RPD>1.90) was obviously improved with in situ vis-NIR spectra compared to PLSR algorithm, and comparable or even better than results generated using laboratory-based spectra with PLSR; (iii) in terms of AP and AK, poor predictions were obtained with in situ spectra (R²<0.5, RPD<1.50) either using PLSR or LS-SVM. The results highlight the use of LS-SVM for in situ vis-NIR spectroscopic estimation of soil properties of paddy soils.     

Determination of Aboveground Net Primary Productivity and Plant Traits in Grasslands with Near-Infrared Reflectance Spectroscopy

Proposed links between biodiversity and ecosystem processes have generated intense interest in the linkage between aboveground net primary productivity (ANPP) and soil C storage. Quantity and quality of ANPP largely depend on plant functional groups and management practices. In a context of environmental change (that is, land-use and climate) long-term studies of ANPP and functional groups are gaining interest. However, rapid determination of ANPP and functional groups are often limited in time and money, resulting in less than ideal sampling schemes and replications. Near-infrared reflectance spectroscopy (NIRS) can relieve constraints of labor intensive hand-sorting by providing quick, non-destructive, and quantitative analyses of a range of organic constituents (for example, plant tissues). Here, we investigated the potential of a NIRS method to rapidly predict harvested green aboveground biomass, the proportion of dead material, and simple functional plant traits, necessary to determine ANPP and related ecosystem properties. The issue was investigated for two independent grassland experiments of contrasted long-term field management (high vs. low grazing and N fertilization). Our results show that NIRS analyses are well suited to determine ANPP (12 and 19% error of prediction) and simple plant traits (error 9%) of contrasted treatment of two independent multi-species grasslands. Moreover, we show that calibration may be simplified when compared to commonly used protocols, which offers ecologists enormous analytical power.     

Application of Fourier Transform Near-Infrared Spectroscopy Combined with High-Performance Liquid Chromatography in Rapid and Simultaneous Determination of Essential Components in Crude Radix Scrophulariae

A method is described using rapid and sensitive Fourier transform near-infrared spectroscopy combined with high-performance liquid chromatography–diode array detection for the simultaneous identification and determination of four bioactive compounds in crude Radix Scrophulariae samples. Partial least squares regression is selected as the analysis type and multiplicative scatter correction, second derivative, and Savitzky–Golay filter were adopted for the spectral pretreatment. The correlation coefficients (R) of the calibration models were above 0.96 and the root mean square error of predictions were under 0.028. The developed models were applied to unknown samples with satisfactory results. The established method was validated and can be applied to the intrinsic quality control of crude Radix Scrophulariae.KEY WORDS: crude Radix Scrophulariae, FT-NIRS, HPLC-DAD, quality control, quantification     

Real-Time Monitoring of Slow-Wave Sleep by Electroencephalogram Variance

Based on statistical variance as an index of electroencephalogram (EEG) parameters, we monitored slow-wave sleep in both humans and rats in real time and on-line with a widely used personal computer. This EEG variance method may be a useful tool to carry out biological rhythm research, including sleep studies.