Robustness of NIR calibrations for soluble solids in intact melon and pineapple

The soluble solids content of intact fruit can be measured non-invasively by near infrared spectroscopy, allowing ���sweetness��� grading of individual fruit. However, little information is available in the literature with respect to the robustness of such calibrations. We developed calibrations based on a restricted wavelength range (700���1100 nm), suitable for use with low-cost silicon detector systems, using a stepwise multiple linear regression routine. Calibrations for total soluble solids (��Brix) in intact pineapple fruit were not transferable between summer and winter growing seasons. A combined calibration (data of three harvest dates) validated reasonably well against a population set drawn from all harvest dates (r2 = 0.72, SEP = 1.84 ��Brix). Calibrations for Brix in melon were transferable between two of the three varieties examined. However, a lack of robustness of calibration was indicated by poor validation within populations of fruit harvested at different times. Further work is planned to investigate the robustness of calibration across varieties, growing districts and seasons.

Assessment of internal quality attributes of mandarin fruit. 1. NIR calibration model development

The utility of near infrared spectroscopy as a non-invasive technique for the assessment of internal eating quality parameters of mandarin fruit (Citrus reticulata cv. Imperial) was assessed. The calibration procedure for the attributes of TSS (total soluble solids) and DM (dry matter) was optimised with respect to a reference sampling technique, scan averaging, spectral window, data pre-treatment (in terms of derivative treatment and scatter correction routine) and regression procedure. The recommended procedure involved sampling of an equatorial position on the fruit with 1 scan per spectrum, and modified partial least squares model development on a 720���950-nm window, pre-treated as first derivative absorbance data (gap size of 4 data points) with standard normal variance and detrend scatter correction. Calibration model performance for the attributes of TSS and DM content was encouraging (typical Rc2 of >0.75 and 0.90, respectively; typical root mean squared standard error of calibration of <0.4 and 0.6%, respectively), whereas that for juiciness and total acidity was unacceptable. The robustness of the TSS and DM calibrations across new populations of fruit is documented in a companion study.

Assessment of internal quality attributes of mandarin fruit. 2. NIR calibration model robustness

The robustness of multivariate calibration models, based on near infrared spectroscopy, for the assessment of total soluble solids (TSS) and dry matter (DM) of intact mandarin fruit (Citrus reticulata cv. Imperial) was assessed. TSS calibration model performance was validated in terms of prediction of populations of fruit not in the original population (different harvest days from a single tree, different harvest localities, different harvest seasons). Of these, calibration performance was most affected by validation across seasons (signal to noise statistic on root mean squared error of prediction of 3.8, compared with 20 and 13 for locality and harvest day, respectively). Procedures for sample selection from the validation population for addition to the calibration population (���model updating���) were considered for both TSS and DM models. Random selection from the validation group worked as well as more sophisticated selection procedures, with approximately 20 samples required. Models that were developed using samples at a range of temperatures were robust in validation for TSS and DM.

NIR model development and robustness in prediction of melon fruit total soluble solids

Near infrared spectroscopy (NIRS) can be used for the on-line, non-invasive assessment of fruit for eating quality attributes such as total soluble solids (TSS). The robustness of multivariate calibration models, based on NIRS in a partial transmittance optical geometry, for the assessment of TSS of intact rockmelons (Cucumis melo) was assessed. The mesocarp TSS was highest around the fruit equator and increased towards the seed cavity. Inner mesocarp TSS levels decreased towards both the proximal and distal ends of the fruit, but more so towards the proximal end. The equatorial region of the fruit was chosen as representative of the fruit for near infrared assessment of TSS. The spectral window for model development was optimised at 695-1045 nm, and the data pre-treatment procedure was optimised to second-derivative absorbance without scatter correction. The 'global' modified partial least squares (MPLS) regression modelling procedure of WINISI (ver. 1.04) was found to be superior with respect to root mean squared error of prediction (RMSEP) and bias for model predictions of TSS across seasons, compared with the 'local' MPLS regression procedure. Updating of the model with samples selected randomly from the independent validation population demonstrated improvement in both RMSEP and bias with addition of approximately 15 samples.

The sensitivity of updated NIR PLS models for fruit sorting to initial parameter settings

Partial least squares regression models on NIR spectra are often optimised (for wavelength range, mathematical pretreatment and outlier elimination) in terms of calibration terms of validation performance with reference to totally independent populations.

Carbon dynamics in peatlands under changing hydrology : Effects of water level drawdown on litter quality, microbial enzyme activities and litter decomposition rates

Pristine peatlands are carbon (C) accumulating wetland ecosystems sustained by a high water level (WL) and consequent anoxia that slows down decomposition. Persistent WL drawdown as a response to climate and/or land-use change directly affects decomposition: increased oxygenation stimulates decomposition of the old C (peat) sequestered under prior anoxic conditions. Responses of the new C (plant litter) in terms of quality, production and decomposability, and the consequences for the whole C cycle of peatlands are not fully understood. WL drawdown induces changes in plant community resulting in shift in dominance from Sphagnum and graminoids to shrubs and trees. There is increasing evidence that the indirect effects of WL drawdown via the changes in plant communities will have more impact on the ecosystem C cycling than any direct effects. The aim of this study is to disentangle the direct and indirect effects of WL drawdown on the new C by measuring the relative importance of 1) environmental parameters (WL depth, temperature, soil chemistry) and 2) plant community composition on litter production, microbial activity, litter decomposition rates and, consequently, on the C accumulation. This information is crucial for modelling C cycle under changing climate and/or land-use. The effects of WL drawdown were tested in a large-scale experiment with manipulated WL at two time scales and three nutrient regimes. Furthermore, the effect of climate on litter decomposability was tested along a north-south gradient. Additionally, a novel method for estimating litter chemical quality and decomposability was explored by combining Near infrared spectroscopy with multivariate modelling. WL drawdown had direct effects on litter quality, microbial community composition and activity and litter decomposition rates. However, the direct effects of WL drawdown were overruled by the indirect effects via changes in litter type composition and production. Short-term (years) responses to WL drawdown were small. In long-term (decades), dramatically increased litter inputs resulted in large accumulation of organic matter in spite of increased decomposition rates. Further, the quality of the accumulated matter greatly changed from that accumulated in pristine conditions. The response of a peatland ecosystem to persistent WL drawdown was more pronounced at sites with more nutrients. The study demonstrates that the shift in vegetation composition as a response to climate and/or land-use change is the main factor affecting peatland ecosystem C cycle and thus dynamic vegetation is a necessity in any models applied for estimating responses of C fluxes to changes in the environment. The time scale for vegetation changes caused by hydrological changes needs to extend to decades. This study provides grouping of litter types (plant species and part) into functional types based on their chemical quality and/or decomposability that the models could utilize. Further, the results clearly show a drop in soil temperature as a response to WL drawdown when an initially open peatland converts into a forest ecosystem, which has not yet been considered in the existing models.

Monitorizaci��n avanzada en el posoperatorio de las cardiopat��as cong��nitas : motorizaci��n hemodin��mica avanzada en el posoperatorio de cardiopat��as cong��nitas mediante termodiluci��n transpulmonar y espectroscopia cercana al infrarrojo

196 p. : graf.

Aplica����es de m��todos de classifica����o e calibra����o multivariada acoplados com t��cnicas espectrosc��picas em amostras ambientais e alimentos

Este trabalho de pesquisa descreve dois estudos de caso de m��todos quimiom��tricos empregados para a quantifica����o de hidrocarbonetos polic��clicos arom��ticos HPAs (naftaleno, fluoreno, fenantreno e fluoranteno) em ��gua pot��vel usando espectroscopia de fluoresc��ncia molecular e a classifica����o e caracteriza����o de sucos de uva e seus par��metros de qualidade atrav��s de espectroscopia de infravermelho pr��ximo. O objetivo do primeiro estudo �� a aplica����o combinada de m��todos quimiom��tricos de segunda ordem (N-PLS, U-PLS, U-PLS/RBL e PARAFAC) e espectrofluorimetria para determina����o direta de HPAs em ��gua pot��vel, visando contribuir para o conhecimento do potencial destas metodologias como alternativa vi��vel para a determina����o tradicional por cromatografia univariada. O segundo estudo de caso destinado �� classifica����o e determina����o de par��metros de qualidade de sucos de uva, densidade relativa e teor de s��lidos sol��veis totais, foi medida por espectroscopia de infravermelho pr��ximo e m��todos quimiom��tricos. Diversos m��todos quimiom��tricos, tais como HCA, PLS-DA, SVM-DA e SIMCA foram investigados para a classifica����o amostras de sucos de uva ao mesmo tempo que m��todos de calibra����o multivariada de primeira ordem, tais como PLS, iPLS e SVM-LS foram usadas para a predi����o dos par��metros de qualidade. O princ��pio orientador para o desenvolvimento dos estudos aqui descritos foi a necessidade de metodologias anal��ticas com custo, tempo de execu����o e facilidade de opera����o melhores e menor produ����o de res��duos do que os m��todos atualmente utilizados para a quantifica����o de HPAs, em ��gua de torneira, e classifica����o e caracteriza����o das amostras de suco de uva e seus par��metros de qualidade

Acoplamento de t��cnicas espectrom��tricas com m��todos quimiom��tricos de classifica����o e calibra����o multivariada em alimentos

Este trabalho de pesquisa descreve tr��s estudos de utiliza����o de m��todos quimiom��tricos para a classifica����o e caracteriza����o de ��leos comest��veis vegetais e seus par��metros de qualidade atrav��s das t��cnicas de espectrometria de absor����o molecular no infravermelho m��dio com transformada de Fourier e de espectrometria no infravermelho pr��ximo, e o monitoramento da qualidade e estabilidade oxidativa do iogurte usando espectrometria de fluoresc��ncia molecular. O primeiro e segundo estudos visam �� classifica����o e caracteriza����o de par��metros de qualidade de ��leos comest��veis vegetais utilizando espectrometria no infravermelho m��dio com transformada de Fourier (FT-MIR) e no infravermelho pr��ximo (NIR). O algoritmo de Kennard-Stone foi usado para a sele����o do conjunto de valida����o ap��s an��lise de componentes principais (PCA). A discrimina����o entre os ��leos de canola, girassol, milho e soja foi investigada usando SVM-DA, SIMCA e PLS-DA. A predi����o dos par��metros de qualidade, ��ndice de refra����o e densidade relativa dos ��leos, foi investigada usando os m��todos de calibra����o multivariada dos m��nimos quadrados parciais (PLS), iPLS e SVM para os dados de FT-MIR e NIR. V��rios tipos de pr��-processamentos, primeira derivada, corre����o do sinal multiplicativo (MSC), dados centrados na m��dia, corre����o do sinal ortogonal (OSC) e varia����o normal padr��o (SNV) foram utilizados, usando a raiz quadrada do erro m��dio quadr��tico de valida����o cruzada (RMSECV) e de predi����o (RMSEP) como par��metros de avalia����o. A metodologia desenvolvida para determina����o de ��ndice de refra����o e densidade relativa e classifica����o dos ��leos vegetais �� r��pida e direta. O terceiro estudo visa �� avalia����o da estabilidade oxidativa e qualidade do iogurte armazenado a 4C submetido �� luz direta e mantido no escuro, usando a an��lise dos fatores paralelos (PARAFAC) na luminesc��ncia exibida por tr��s fluor��foros presentes no iogurte, onde pelo menos um deles est�� fortemente relacionado com as condi����es de armazenamento. O sinal fluorescente foi identificado pelo espectro de emiss��o e excita����o das subst��ncias fluorescentes puras, que foram sugeridas serem vitamina A, triptofano e riboflavina. Modelos de regress��o baseados nos escores do PARAFAC para a riboflavina foram desenvolvidos usando os escores obtidos no primeiro dia como vari��vel dependente e os escores obtidos durante o armazenamento como vari��vel independente. Foi vis��vel o decaimento da curva anal��tica com o decurso do tempo da experimenta����o. Portanto, o teor de riboflavina pode ser considerado um bom indicador para a estabilidade do iogurte. Assim, �� poss��vel concluir que a espectroscopia de fluoresc��ncia combinada com m��todos quimiom��tricos �� um m��todo r��pido para monitorar a estabilidade oxidativa e a qualidade do iogurte

Estudo da previs��o de propriedades do biodiesel utilizando espectros de infravermelho e calibra����o multivariada

O biodiesel tem sido amplamente utilizado como uma fonte de energia renov��vel, que contribui para a diminui����o de demanda por diesel mineral. Portanto, existem v��rias propriedades que devem ser monitoradas, a fim de produzir e distribuir biodiesel com a qualidade exigida. Neste trabalho, as propriedades f��sicas do biodiesel, tais como massa espec��fica, ��ndice de refra����o e ponto de entupimento de filtro a frio foram medidas e associadas a espectrometria no infravermelho pr��ximo (NIR) e espectrometria no infravermelho m��dio (Mid-IR) utilizando ferramentas quimiom��tricas. Os m��todos de regress��o por m��nimos quadrados parciais (PLS), regress��o de m��nimos quadrados parciais por intervalos (iPLS), e regress��o por m��quinas de vetor de suporte (SVM) com sele����o de vari��veis por Algoritmo Gen��tico (GA) foram utilizadas para modelar as propriedades mencionadas. As amostras de biodiesel foram sintetizadas a partir de diferentes fontes, tais como canola, girassol, milho e soja. Amostras adicionais de biodiesel foram adquiridas de um fornecedor da regi��o sul do Brasil. Em primeiro lugar, o pr��-processamento de corre����o de linha de base foi usado para normalizar os dados espectrais de NIR, seguidos de outros tipos de pr��-processamentos que foram aplicados, tais como centraliza����o dos dados na m��dia, 1 derivada e varia����o de padr��o normal. O melhor resultado para a previs��o do ponto de entupimento de filtro a frio foi utilizando os espectros de Mid-IR e o m��todo de regress��o GA-SVM, com alto coeficiente de determina����o da previs��o, R2Pred=0,96 e baixo valor da Raiz Quadrada do Erro M��dio Quadr��tico da previs��o, RMSEP (C)= 0,6. Para o modelo de previs��o da massa espec��fica, o melhor resultado foi obtido utilizando os espectros de Mid-IR e regress��o por PLS, com R2Pred=0,98 e RMSEP (g/cm3)= 0,0002. Quanto ao modelo de previs��o para o ��ndice de refra����o, o melhor resultado foi obtido utilizando os espectros de Mid-IR e regress��o por PLS, com excelente R2Pred=0,98 e RMSEP= 0,0001. Para esses conjuntos de dados, o PLS e o SVM demonstraram sua robustez, apresentando-se como ferramentas ��teis para a previs��o das propriedades do biodiesel estudadas

Layer-by-layer assembly of carbon nanotubes and Prussian blue nanoparticles: A potential tool for biosensing devices

A promising method for assembling carbon nanotubes (CNTs) and poly(diallyldimethylammonium chloride) protected Prussian blue nanoparticles (P-PB) to form three-dimensional (3D) nanostructured films is proposed. The electrostatic interaction, combined with layer-by-layer self-assembly (LBL), between negatively charged CNTs and positively charged P-PB is strong enough to drive the formation of the 3D nanostructured films. Thus, prepared multilayer films were characterized by ultraviolet-visible-near-infrared spectroscopy (UV-vis-NIR), scanning electron microscopy (SEM) and cyclic voltammetry (CV).

High-efficiency and low-cost hybrid nanomaterial as enhancing electrocatalyst: Spongelike AWN core/shell nanomaterial with hollow cavity

A high-efficiency and low-cost spongelike Au/Pt core/shell electrocatalyst with hollow cavity has been facilely obtained via a simple two-step wet chemical process. Hollow gold nanospheres were first synthesized via a modified galvanic replacement reaction between Co nanoparticles in situ produced and HAUCl(4). The as-prepared gold hollow spheres were employed as seeds to further grow spongelike Pt shell. It is found that the surface of this hybrid nanomaterial owns many Pt nanospikes, which form a spongelike nanostructure. All experimental data including scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-vis-near-infrared spectroscopy have been employed to characterize the obtained Au/Pt hybrid nanomaterial. The rapid development of fuel cell has inspired us to investigate the electrocatalytic properties for dioxygen and methanol of this novel hybrid nanomaterial. Spongelike hybrid nanomaterial mentioned here exhibits much higher catalytic activity for dioxygen reduction and methanol oxidation than the common Pt electrode.

Bifunctional Au@Pt hybrid nanorods

The controlled synthesis of bifunctional Au@Pt hybrid nanorods has been realized through a simple wet chemical approach. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis-near infrared spectroscopy (UV-vis-NIR) were employed to characterize the obtained hybrid nanorods. TEM results indicate that the thickness of Pt nanoislands on the surfaces of gold nanorods can be easily tunable via controlling the molar ratio of An nanorods to the H2PtCl6. These Au@Pt hybrid nanorods have dual functions, which can be used not only for surface enhanced Raman spectroscopy (SERS), but also to exhibit good catalytic activity for 02 reduction. It is expected that these hybrid nanorods can be used as new functional building blocks to assemble novel three-dimensional (31)) complex multicomponent nanostructures, which are believed to be useful for electrochemical nanodevices.

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By now, there are still many unsolved questions about associative priming. This study used process dissociation paradigm, perceptual identification task and speeded naming task,together with near infrared spectroscopy, to investigate priming for new associations and its brain mechanisms systematically. The results showed there was interaction between level of processing and unitization in affecting associative priming. When comparing with shallow encoding unrelated word pairs, the activation of both sides of prefrontal lobe was stronger, which suggested prefrontal lobe had relations with memory for new associations. Medial temporal lobe and frontal lobe lesioned patients were tested respectively using methods of perceptual identification task and speeded naming task. Both brain regions participated in associative priming. Medial temporal lobe mediated unitization between unrelated items. Frontal lobe contributed to priming for new associations by elaborative processing, inhibiting irrelevant information, selective attending to tasks, and establishing some effective strategies. In addition, normal subjects needed to aware the relationship between study and test to form associative priming and densely memory deficit patients could not form memory for new associations. In conclusion, the results further demonstrated that perceptual representation system could not support priming for new associations alone. Medial temporal lobe and frontal lobe played roles in priming for new associations, and there was some relation between associative priming and conscious retrieval processing.

Preparation and Evaluation of Sustained-Release Matrix Tablets Based on Metoprolol and an Acrylic Carrier Using Injection Moulding

Sustained-release matrix tablets based on Eudragit RL and RS were manufactured by injection moulding. The influence of process temperature; matrix composition; drug load, plasticizer level; and salt form of metoprolol: tartrate (MPT), fumarate (MPF) and succinate (MPS) on ease of processing and drug release were evaluated. Formulations composed of 70/30% Eudragit RL/MPT showed the fastest drug release, substituting part of Eudragit RL by RS resulted in slower drug release, all following first-order release kinetics. Drug load only affected drug release of matrices composed of Eudragit RS: a higher MPT concentration yielded faster release rates. Adding triethyl citrate enhanced the processability, but was detrimental to long-term stability. The process temperature and plasticizer level had no effect on drug release, whereas metoprolol salt form significantly influenced release properties. The moulded tablets had a low porosity and a smooth surface morphology. A plasticizing effect of MPT, MPS and MPF on Eudragit RS and Eudragit RL was observed via DSC and DMA. Solubility parameter assessment, thermal analysis and X-ray diffraction demonstrated the formation of a solid solution immediately after production, in which H-bonds were formed between metoprolol and Eudragit as evidenced by near-infrared spectroscopy. However, high drug loadings of MPS and MPF showed a tendency to recrystallise during storage. The in vivo performance of injection-moulded tablets was strongly dependent upon drug loading. �� 2012 American Association of Pharmaceutical Scientists.