The chemometrics approach applied to FTIR spectral data for the analysis of rice bran oil in extra virgin olive oil

Among eleven studied vegetable oils, rice bran oil (RBO) has the close similarity to extra virgin olive oil (EVOO) in terms of FTIR spectra, as shown in the score plot of first and second principal components. The peak intensities at 18 frequency regions were used as matrix variables in principal component analysis (PCA). Consequently, the presence of RBO in EVOO is difficult to detect. This study aimed to use the chemometrics approach, namely discriminant analysis (DA) and multivariate calibrations of partial least square and principle component regression to analyze RBO in EVOO. DA was used for the classification of EVOO and EVOO mixed with RBO. Multivariate calibrations were exploited for the quantification of RBO in EVOO. The combined frequency regions of 1200-900 and 3020-3000 cm^− 1 were used for such analysis. The results showed that no misclassification was reported for the classification of EVOO and EVOO mixed with RBO. Partial least square regression either using normal or first derivative FTIR spectra can be successfully used for the quantification of RBO in EVOO. In addition, analysis of fatty acid composition can complement the results obtained from FTIR spectral data.     

Application of chemometric methods to differential scanning calorimeter (DSC) to estimate nimodipine polymorphs from cosolvent system

The focus of this study was to evaluate the applicability of chemometrics to differential scanning calorimetry data (DSC) to evaluate nimodipine polymorphs. Multivariate calibration models were built using DSC data from known mixtures of the nimodipine modification. The linear baseline correction treatment of data was used to reduce dispersion in thermograms. Principal component analysis of the treated and untreated data explained 96% and 89% of the data variability, respectively. Score and loading plots correlated variability between samples with change in proportion of nimodipine modifications. The R² for principal component regression (PCR) and partial lease square regression (PLS) were found to be 0.91 and 0.92. The root mean square of standard error of the treated samples for calibration and validation in PCR and PLS was found to be lower than the untreated sample. These models were applied to samples recrystallized from a cosolvent system, which indicated different proportion of modifications in the mixtures than those obtained by placing samples under different storage conditions. The model was able to predict the nimodipine modifications with known margin of error. Therefore, these models can be used as a quality control tool to expediently determine the nimodipine modification in an unknown mixture.     

Quantitative analysis of hemoglobin content in polymeric nanoparticles as blood substitutes using Fourier transform infrared spectroscopy

Based on the penetrability of IR within the polymeric nanoparticles, a novel Fourier transform infrared spectroscopy (FTIR) method, with polyacrylonitrile (PAN) as the internal reference standard, was developed to quantify the hemoglobin (Hb) content in Hb-based polymeric nanoparticles (HbPN). The HbPN was fabricated by double emulsion method from poly(ethylene glycol)–poly(lactic acid)–poly(ethylene glycol) triblock copolymers. Depending on the characteristic un-overlapped IR absorbances at 1540 cm⁻¹ of Hb (amide II) and at 2241 cm⁻¹ of PAN (–C≡N), calibration equations, presenting the peak height ratio of Hb and PAN as a function of the weight ratio of Hb and PAN, were established. This new quantification method is validated and used to the determination Hb content in HbPN. Due to the good results of this calibration strategy, the proposed simple FTIR approach with minimal sample-needed and solvent-free makes it useful for routine analysis of protein content and could be also applied to any other drug/protein encapsulated particles.     

In Vitro Repairability for the Disordered Skin by Pyrrolidone-Carboxylate Sodium

Abstract

The excised skin of nude mice and the porcine stratum corneum pretreated with vitamin C, oleic acid or DMSO were examined by Micro FTIR spectroscopy. The C-H stretching vibrational peaks near 2920 cm^-1(asymmetric CH₂) and 2850 cm^-1(symmetric CH₂) shifted to higher wavenumber due to the lipid disorder after in vitro treatment with above enhancers. These higher wavenumbers of CH₂stretching bands decreased gradually to the lower region after co-treatment or post-treatment with pyrrolidone-carboxylate sodium (PCA Na), dependent on the PCA Na concentration and the time of treatment. When PCA Na coexisted with vitamin C in cell compartment, the competition effect between PCA Na and vitamin C was observed. The oleic acid inserted into the lipid structure to make a larger spectral shift of both stretching bands but less repairing ability after PCA Na treatment. On the other hand, DMSO only displaced the bound protein water and slightly loosened the lipid structure to result in narrower spectral shift of stretching bands and easier and better repairing after PCA Na application.     

Measurement of the diffusion coefficient of rare earth species in PbO-B2O3 flux used for liquid phase epitaxial growth of magnetic garnet films

The solute diffusion coefficient in a PbO-B₂O₃ flux system used for the growth of magnetic garnet films has been measured by two different techniques and found to be (5±1.5)×10^?7 cm²/sec in the growth temperature range of 840°C–887°C. In the first technique, for a nearly stagnant melt, the film thickness is proportional to the square root of the growth time after subtraction of the residual effects of convection. In the second technique the melt is stirred by rotating the substrate. The growth rate is constant after an initial transient, and is proportional to the square root of the rotation rate.     

Controlling sugar quality on the basis of fluorescence fingerprints using robust calibration

The aim of our study was to highlight the benefits of robust calibration in the context of process control. Two properties were monitored — the color and ash content of sugar samples. It was shown for the data being studied that robust models, constructed using the partial robust M-regression technique, have a better fit to the majority of the data and prediction properties than the classic partial least squares and N-way partial least squares models. In particular, the constructed calibration models were characterized by a root mean square errors improved by 1.60% and 1.82% and a root mean square errors of prediction (for independent test samples) improved by 2.39% and 1.11% compared to classic partial least squares models constructed for color and ash content, respectively.     

Fabrication and characterization of Ge nanocrystalline growth by ion implantation in SiO<Subscript>2</Subscript> matrix

Ge nanocrystallites (Ge-nc) have been formed by ion implantation of Ge⁺⁷⁴ into SiO₂ matrix, thermally grown on p-type Si substrates. The Ge-nc are examined by Raman spectroscopy, photoluminescence (PL) and Fourier transform infrared spectroscopy (FTIR). The samples were prepared with various implantation doses [0.5; 0.8; 1; 2; 3; 4] × 10¹⁶ cm⁻² with 250 keV energy. After implantation, the samples were annealed at 1,000 °C in forming gas atmosphere for 1 h. Raman intensity variation with implantation doses is observed, particularly for the peak near 304 cm⁻¹. It was found that the sample implanted with a doses of 2 × 10¹⁶ cm⁻² shows maximum photoluminescence intensity at about 3.2 eV. FTIR analysis shows that the SiO₂ film moved off stoichiometry due to Ge⁺⁷⁴ ion implantation, and Ge oxides are formed in it. This result is shown as a reduction of GeO_x at exactly the doses corresponding to the maximum blue-violet PL emission and the largest Raman emission at 304 cm⁻¹. This intensity reduction can be attributed to a larger portion of broken Ge–O bonds enabling a greater number of Ge atoms to participate in the cluster formation and at the same time increasing the oxygen vacancies. This idea would explain why the FTIR peak decreases at the same implantation doses where the PL intensity increases.     

Nanobiosensor for the detection and quantification of pork adulteration in meatball formulation

A 27-nucleotide AluI fragment of swine cytochrome b (cytb) gene was integrated to 3-nm diameter citrate–tannate-coated gold nanoparticles to fabricate a species-specific nanobiosensor. The biosensor was applied to authenticate pork adulteration in meatball formulation, which is a favourite food in many Asian and European countries. The sensor was found to be sensitive enough to detect 1% pork in raw and cooked meatballs, prepared from the previously mixed pork and beef in specific ratios (% w/w). The hybridisation kinetics of the hybrid biosensor was studied with synthetic targets from moderate to extreme target concentrations and a hyperbolic relationship was found. However, linearity was observed with probe/target ratios 4:1 to 1:2. This part of the curve quantified target DNA in ready-to-eat mixed meatball preparations with more than 90% accuracy. The biosensor probe was hybridised with a target DNA that was several-fold shorter than a typical PCR-template. This offered the detection and quantitation of potential targets in highly processed meat products or extensively degraded samples where PCR-based identification technique might not work due to the fragmentation of comparatively longer DNA. We believe that the assay can be used as an alternative to qPCR for determining shorter size DNA sequences in degraded samples to address a range of biological problems, such as food analysis, bio-diagnostics, environmental monitoring, genetic screening and forensic investigations.     

Assessment of pareto calibration, stability, and wavelength selection

Recent work has shown that ridge regression (RR) is Pareto to partial least squares (PLS) and principal component regression (PCR) when the variance indicator Euclidian norm of the regression coefficients, //p//, is plotted against the bias indicator root mean square error of calibration (RMSEC). Simplex optimization demonstrates that RR is Pareto for several other spectral data sets when //p// is used with RMSEC and the root mean square error of evaluation (RMSEE) as optimization criteria. From this investigation, it was observed that while RR is Pareto optimal, PLS and PCR harmonious models are near equivalent to harmonious RR models. Additionally, it was found that RR is Pareto robust, i.e., models formed at one temperature were then used to predict samples at another temperature. Wavelength selection is commonly performed to improve analysis results such that bias indicators RMSEC, RMSEE, root mean square error of validation, or root mean square error of cross-validation decrease using a subset of wavelengths. Just as critical to an analysis of selected wavelengths is an assessment of variance. Using wavelengths deemed optimal in a previous study, this paper reports on the variance/bias tradeoff. An approach that forms the Pareto model with a Pareto wavelength subset is suggested.     

Direct determination of unsaturation level of milk fat using Raman spectroscopy

We have demonstrated the potential of visible Raman spectroscopy in combination with chemometric analysis as a fast and simple tool for the determination of the unsaturation level of milk fat. The Raman measurements have been performed directly on liquid milk and on fat extracted from liquid milk. The Raman spectra taken from the extracted fat showed a higher resolution. The spectra directly obtained from the milk samples had some fluorescence background but nevertheless yielded the desired information. For calibration purposes, the iodine value (IV) was determined in all cases in order to evaluate the unsaturation level of the investigated samples. Two separate calibration models have been constructed; one for the milk samples and the second one for the extracted fat. The accuracy of these calibration models was estimated using the root mean square error of calibration and validation (RMSE) and the coefficient of determination (R(2)) between actual and predicted values.     

Proton induced modification in makrofol-DE

Irradiation effects of a 3 MeV proton beam on polycarbonate (makrofol-DE (MFD)) have been studied with respect to its electrical, thermal and structural behaviour by using an LCR meter, DSC/TGA and FTIR spectroscopy. The dielectric loss/constant was observed to change with the fluence. Thermal analysis revealed that chain scission is the dominant phenomena in irradiated samples based on the reduction of its thermal stability by about 19% at a fluence of 10¹⁵ ions/cm², which is also corroborated by FTIR spectra. No significant change in intensity of the absorbance bands of the irradiated sample was observed up to a fluence of 10¹⁴ ions/cm² while on increasing fluence (10¹⁵ ions/cm²) the polymer structure was modified. It appears from DSC thermograms thatT _g is observed to change with fluence.     

In Situ Synthesis of Cuprous Oxide/Cellulose Nanofibers Gel and Antibacterial Properties

Cellulose nanofibers were synthesized by acetobacter xylinum (xylinum 1.1812). The cellulose nanofibers with 30-90 nm width constructed three-dimension network gel, which could be used as a wound dressing since it can provide moist environment to a wound. However, cellulose nanofibers have no antimicrobial activity to prevent wound infection. To achieve antimicrobial activity, the cellulose nanofibers can load cuprous oxide (Cu₂O) particles on the surface. The cuprous oxide is a kind of safe antibacterial material. The copper ions can be reduced into cuprous oxides by reducing agents such as glucose, N₂H₄ and sodium hypophosphite. The cellulose nanofibers network gel was soaked in CuSO₄ solution and filled with copper ions. The cuprous oxide nanoparticles were in situ synthesized by glucose and embedded in cellulose nanofibers network. The morphologies and structure of the composite gel were analyzed by FESEM, FTIR, WAXRD and inductively coupled plasma (ICP). The sizes of Cu₂O embedded in cellulose nanofibers network are 200-500 nm wide. The peak at 605 cm⁻¹ attributed to Cu(I)-O vibration of Cu₂O shits to 611 cm⁻¹ in the Cu₂O/ cellulose composite. The Cu₂O/ cellulose nanofibers composite reveals the obvious characteristic XRD pattern of Cu₂O and the results of ICP show that the content of Cu₂O in the composite is 13.1%. The antibacterial tests prove that the Cu₂O/ cellulose nanofibers composite has the high antibacterial activities which is higher against S. aureus than against E. coli.     

Effects of active modified atmosphere on lipid and protein oxidation,moisture migration and quality properties of beef steaks

Fresh beef is a typically perishable food because of its high water and protein content; thus, it requires proper packaging condition and storage temperature to ensure its quality. In this study, the beef steaks were stored at 4°C under HiO₂ modified atmosphere packaging (MAP) (78.8% O₂ + 18.8% CO₂ + 2.4% N₂) and HiCO₂ MAP (60.0% CO₂ + 40.0% N₂). The traditional air packaging (AP) and vacuum packaging (VP) were used as the controls. The total viable count (TVC), colour, water holding capacity (WHC), myofibrillar protein (MP) oxidation and lipid oxidation of beef meat were investigated. The moisture distribution and migration were also analysed using the low-field nuclear magnetic resonance (LF-NMR). The association amongst all parameters was analysed by correlation analysis and principal component analysis (PCA). The results showed that the TVC values in the HiCO₂ MAP (5.6 log CFU/g) steaks were lower than those of VP (5.9 log CFU/g), AP (7.0 log CFU/g) and HiO₂ MAP (6.3 log CFU/g) steaks because of the sufficient CO₂ after 15 days of chilled storage. The bright red colour and the higher WHC were maintained in the HiO₂ MAP steaks than in the AP group during storage. However, higher levels of protein and lipid oxidation also occurred. The beef steaks stored under HiCO₂ MAP had the lowest protein and lipid oxidation and highest value of immobile water content and WHC, however, similar to the VP group, the bright red colour was not shown. The moisture attributes (drip loss, cooking loss and P₂₃), protein oxidation (protein solubility and carbonyl content) and lipid oxidation (TBARS value) have shown a close correlation by correlation analysis and PCA. Overall, two different packaging methods of MAP can prolong microbial-shelf life and maintain higher WHC of beef steaks compared to AP and VP steaks, but higher oxidation level in HiO₂ MAP and unattractive colour in HiCO₂ MAP are concerns that need to be addressed.     

Consumers' valuation of two packaging aspects for fresh lamb meat: Vacuum and information labels

The use of vacuum packaging for fresh meat with low rate of turnover in the supermarket shelves, as it is the case of lamb meat in Spain, is recommended. Because the amount of mandatory information on fresh‐meat labels has increased, there is a need to design new labels to enhance the support for this information. Therefore, to anticipate the consumer's acceptance of vacuum packaging and the preferences for newly designed labels is of vital importance. This is the objective of the paper; in particular, it measures the consumers' relative importance of the vacuum packaging and different labels in relation to other important lamb‐meat characteristics (type of cut, price, and regional indication). To do that, a choice experiment was used and an error‐component random‐parameter model with correlated errors was estimated. Results suggest that consumers positively value all of the attributes except for the new designed labels. In particular, consumers positively value the vacuum packaging but to lesser extent than other lamb‐meat attributes such as the type of cut, the protected geographical indication certification, and the price. However, consumers only value the vacuum packaging in the case of fresh lamb meat with a protected geographical indication certification. Moreover, this valuation is higher for older consumers who use, to a higher extent, their own direct appraisal of the meat and the information on the label when shopping and give less importance to the presence of liquid around the meat.     

Acoustic Chemometric At-Line Characterization for Monitoring Particle Size Fractions in Pneumatically Conveyed Biomass

Reliable on-line/at-line prediction of particle size fractions of biomass material is a process monitoring concern owing to inherent variation in particle size and difficulty in sampling of pneumatically ducted biomass material. A feasibility study on application of acoustic chemometrics for at-line prediction of size fractions of biomass material has been performed, with all models subjected to independent test set validation. This study serves as a platform for at-line characterization of biomass samples from a sampling device extracting biomass samples from pneumatic conveying systems (based on theory of sampling). A prestudy using complex biomass/plastic pellets mixtures was used to test reliability and robustness of the experimental setup. Promising prediction results were achieved (slope, relative root mean square error of prediction (RMSEP_rel), and correlation coefficient (r²) were 1.08, 24.94%, and 0.90, respectively). The same experimental setup was adapted for quantitative prediction of coarse versus fine biomass mixtures (the main objective) with satisfactory results; slope = 0.96, r² = 0.97, RMSEP_(rel) = 11%. A case study was also performed showing the adverse effect of using nonrepresentative coarse versus fine biomass samples for calibration. It is concluded that acoustic chemometrics is a viable technique for at-line prediction of size fractions of representative biomass materials.     

Gaseinlasssystem zur massenspektrometrischen Analyse kleiner Gasproben. Gas Inlet System to Analyse Small Gas Samples by a Mass Spectrometer

A quadrupole mass spectrometer (MS) was used to analyse gas samples taken from human bodies with the aid of hypodermic syringe. Because of the small amount of the produced gas samples (< 1 cm³) a special gas inlet system has been developed and built allowing to transfer the gas samples into a testing volume unadulteratedly concerning size and composition. From the testing volume the gas specimen directly flows through an UHV‐needle valve into the ion source of the MS. After a careful calibration of the MS respecting to the interesting components of the gas sample a quantitative analysis can be carried out with an uncertainty of < 1 %.     

Effect of diet composition on the determination of ash and moisture content in solid cattle manure using visible and near-infrared spectroscopy

Visible and near-infrared (Vis-NIR, 350-2500 nm) diffuse reflection spectroscopy (DRS) models built from "as-collected" samples of solid cattle manure accurately predict concentrations of moisture and crude ash. Because different organic molecules emit different spectral signatures, variations in livestock diet composition may affect the predictive accuracy of these models. This study investigates how differences in livestock diet composition affect Vis-NIR DRS prediction of moisture and crude ash. Spectral signatures of solid manure samples (n = 216) from eighteen groups of cattle on six different diets were used to calibrate and validate partial least squares (PLS) regression models. Seven groups of PLS models were created and validated. In the first group, two-thirds of all samples were randomly selected as the calibration set and the remaining one-third were used for the validation set. In the remaining six groups, samples were grouped by livestock diet (ration). Each ration in turn was held out of calibrations and then used as a validation set. When predicting crude ash, the fully random calibration model produced a root mean square deviation (RMSD) of 2.5% on a dry basis (db), ratio of standard error of prediction to the root mean squared deviation (RPD) of 3.1, bias of 0.14% (db), and correlation coefficient r(2) of 0.90., When predicting moisture, an RMSD of 1.5% on a wet basis (wb), RPD of 4.3, bias of -0.09% (wb), and r(2) of 0.95 was achieved. Model accuracy and precision were not impaired by exclusion of any single ration from model calibration.     

On-line predictions of the aspen fibre and birch bark content in unbleached hardwood pulp, using NIR spectroscopy and multivariate data analysis

An on-line fibre-based near-infrared (NIR) spectrometric analyser was adapted for on-site process analysis at an integrated paperboard mill. The analyser uses multivariate techniques for the quantitative predication of the aspen fibre (aspen) and the birch bark contents of sheets of unbleached hardwood pulp. The NIR analyser is a prototype constructed from standard NIR components. The spectroscopic data was processed by using principal component analysis (PCA) and partial least square (PLS) regression. Three sample sets were collected from three experimental designs, each composed of known pulp contents of birch, aspen and birch bark. Sets 1 and 2 were used for model calibration and set 3 was used to validate the models. The PLS model that produced the best predictions gave an error of prediction (RMSEP) of 13% for aspen and less than 2% for birch bark. Eight components resulted in an R²X of 99.3%, R²Y of 99.6%, and Q² of 95.3%. For additional validation of aspen, three unbleached hardwood samples from the mill's production were calculated to lie between − 7% and + 6%, regarding to the PLS model. When vessel cells were counted under a light microscope a value for the aspen content of 4.7% was obtained. The predictive models evaluated were suitable for quality assessments rather than quantitative determination.     

Structural Characterization of Four South African Fly Ashes and Their Structural Changes with β-Cyclodextrin

This article examines the structural characteristics of four South African fly ashes and their structural changes with β-cyclodextrin so as to compare their structural responses to fly ash-β-cyclodextrin (FA-βCD) composite. The four different fly ashes, obtained from different power stations in South Africa were subjected to x-ray fluorescence (XRF), particle size distribution, x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analysis. FA-βCD composites were subjected to XRD and FTIR analyses. The XRF analysis showed that all the fly ash samples used are in class F with SiO₂ + Al₂O₃ + Fe₂O₃ greater than 70%. The average particle sizes of all fly ash samples were less than 0.075 mm; the major mineral phase in all fly ash samples was quartz (SiO₂). The FTIR analysis showed Si-O-Si asymmetric and Al-O symmetric stretching vibrations in all fly ash samples. FA-βCD composites for all the fly ashes revealed additional upcoming peaks between diffraction angles (2θ) 10° and 25°, which was not in the raw fly ashes. Shift in FTIR spectra frequencies and an additional peak at approximately 1155 cm^?1 attributed to O-Si-O bending vibration were observed in all the composite samples.     

The application of near infrared spectroscopy in the quality control analysis of glass/phenolic resin prepreg

During the manufacture of glass/phenolic resin prepreg cloth, the feasibility of near infrared (NIR) spectroscopy as a technique for the quality control analysis of the resin content, the volatile content and the resin pre-curing degree has been verified. The partial least square (PLS) regression was used to develop the calibration models by utilizing several different spectral pretreatments. The optimum models had determination coefficients (R ²) of 98.29 for the resin content, of 99.50 for the volatile content and of 97.66 for the pre-curing degree, respectively. The root mean square errors of prediction (RMSEP) for the resin content, the volatile content and the pre-curing degree were 0.376%, 0.169% and 0.105%, respectively. The results of the paired t-test revealed that there was no significant difference between the NIR method and the standard method. In the manufacture process of the prepreg cloth, the NIR on-line monitoring results were used to be the instructions for the quality control.