Nondestructive discrimination of ivories and prediction of their specific gravity by Fourier-transform Raman spectroscopy and chemometrics

Fourier-transform (FF) Raman spectroscopy and chemometrics were used for nondestructive analysis of ivories. The discrimination of five kinds of ivories, two subspecies of African elephant, mammoth, hippopotamus, and sperm whale, was investigated, and a calibration model for predicting their specific gravity was developed. FT-Raman spectra were measured in situ for them and chemometrics analyses were carried out for the 3050-350 cm(-1) region. The five kinds of ivories were clearly discriminated from each other on the scores plots of two or three principal components (PCs) obtained by principal component analysis (PCA). The loadings plot for PC 1 shows that the discrimination relies on the content ratio of organic collagenous protein and inorganic hydroxyapatite of ivories. The loadings plot for PC 2 shows that bands due to the CH3 and CH2 stretching modes of the protein also play a role in the discrimination. Using partial least squares regression (PLSR), we developed a calibration model that predicts the specific gravity of the ivories from the FT-Raman spectra. The correlation coefficient and root mean square error of cross validation (RMSECV) of this model were 0.980 and 0.024, respectively.     

Discrimination of ethylene/vinyl acetate copolymers with different composition and prediction of the content of vinyl acetate in the copolymers and their melting points by near-infrared spectroscopy and chemometrics

Near-infrared (NIR) diffuse reflectance spectra have been measured by use of a rotating drawer for pellets of 12 kinds of ethylene/vinyl acetate (EVA) copolymers with vinyl acetate (VA, the comonomer) varying in the 7–44 wt % range. They are unambiguously discriminated from one another by a score plot of the principal component analysis (PCA) Factor 1 and 2, based upon the NIR spectra pretreated by multiplicative scatter correction (MSC). Principal component (PC) weight loadings for Factor 1 show that the discrimination relies largely upon bands due to the overtone and combination modes arising from the VA unit. We have found one “outlier” in the score plot and elucidated its spectral characteristics based upon PC weight loadings for Factor 2. Partial least-squares (PLS) regression has been applied to propose calibration models which predict the VA content in EVA. The models have been prepared for three kinds of pretreatment, the first derivative, the second derivative, and MSC; and four kinds of wavelength regions. The NIR spectra in the 1100–2200 nm region after the MSC treatment has given the best correlation coefficient and standard error of prediction (SEP) of 0.998 and 0.70%, respectively. The calibration models, prepared by NIR diffuse reflectance spectroscopy for the pellet samples, are compared with previously reported models by NIR transmission spectroscopy for the flowing molten samples, and with those by Raman spectroscopy for the pellet samples. PLS regression has also allowed us to predict melting points of the copolymers with the correlation coefficient and SEP of 0.997 and 0.78°C, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1529–1537, 1998     

A spectroscopic study of mechanochemically activated kaolinite with the aid of chemometrics

The study of kaolinite surfaces is of industrial importance. In this work we report the application of chemometrics to the study of modified kaolinite surfaces. DRIFT spectra of mechanochemically activated kaolinites (Kiralyhegy, Zettlitz, Szeg, and Birdwood) were analyzed using principal component analysis (PCA) and multicriteria decision making (MCDM) methods, PROMETHEE and GAIA. The clear discrimination of the Kiralyhegy spectral objects on the two PC scores plots (400-800 and 800-2030 cm(-1)) indicated the dominance of quartz. Importantly, no ordering of any spectral objects appeared to be related to grinding time in the PC plots of these spectral regions. Thus, neither the kaolinite nor the quartz, are systematically responsive to grinding time according to the spectral criteria investigated. The third spectral region (2600-3800 cm(-1)OH vibrations), showed apparent systematic ordering of the Kiralyhegy and, to a lesser extent, Zettlitz spectral objects with grinding time. This was attributed to the effect of the natural quartz on the delamination of kaolinite and the accompanying phenomena (i.e., formation of kaolinite spheres and water). With the MCDM methods, it was shown that useful information on the basis of chemical composition, physical properties and grinding time can be obtained. For example, the effects of the minor chemical components (e.g., MgO, K(2)O, etc.) indicated that the Birdwood kaolinite is arguably the most pure one analyzed. In another MCDM experiment, some support was obtained for the apparent trend with grinding time noted in the PC plot of the OH spectral region.     

Stark widths and shifts of SnI,HgII, HgIII and PbII spectral lines

Stark widths and shifts of neutral and ionized heavy atom spectral lines have been measured and calculated. The Stark parameters of three SnI (284.0, 286.3 and 303.4 nm), five HgII (226.2, 398.4, 222.5, 615.0 and 326.4 nm), two PbII (220.4 and 438.6 nm) and one HgIII (235.4 nm) spectral lines were measured for the first time except the Stark widths of one HgII (398.4 nm) and one PbII (438.6 nm) line. Stark width values for a number of corresponding transitions were calculated on the bases of semiclassical and semiempirical formulae.     

Maize kernel hardness classification by near infrared (NIR) hyperspectral imaging and multivariate data analysis

The use of near infrared (NIR) hyperspectral imaging and hyperspectral image analysis for distinguishing between hard, intermediate and soft maize kernels from inbred lines was evaluated. NIR hyperspectral images of two sets (12 and 24 kernels) of whole maize kernels were acquired using a Spectral Dimensions MatrixNIR camera with a spectral range of 960-1662 nm and a sisuChema SWIR (short wave infrared) hyperspectral pushbroom imaging system with a spectral range of 1000-2498 nm. Exploratory principal component analysis (PCA) was used on absorbance images to remove background, bad pixels and shading. On the cleaned images, PCA could be used effectively to find histological classes including glassy (hard) and floury (soft) endosperm. PCA illustrated a distinct difference between glassy and floury endosperm along principal component (PC) three on the MatrixNIR and PC two on the sisuChema with two distinguishable clusters. Subsequently partial least squares discriminant analysis (PLS-DA) was applied to build a classification model. The PLS-DA model from the MatrixNIR image (12 kernels) resulted in root mean square error of prediction (RMSEP) value of 0.18. This was repeated on the MatrixNIR image of the 24 kernels which resulted in RMSEP of 0.18. The sisuChema image yielded RMSEP value of 0.29. The reproducible results obtained with the different data sets indicate that the method proposed in this paper has a real potential for future classification uses.     

Electrochemical, catalytic and antimicrobial activity of N-functionalized tetraazamacrocyclic binuclear nickel(II) complexes

The five binuclear nickel(II) complexes have been synthesized by the Schiff base condensation of 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclo-tetradecane (PC) with appropriate aliphatic diamines and nickel(II) perchlorate. All the five complexes were characterized by elemental and spectral analysis. The electronic spectra of the complexes show three d-d transition in the range of 550-1055 nm due to 3A2g→3T2g(F), 3A2g→3T1g(F) and 3A2g→3T1g(P). These spin allowed electronic transitions are characteristic of an octahedral Ni2+ center. Electrochemical studies of the complexes show two irreversible one electron reduction waves at cathodic region. The reduction potential of the complexes shifts towards anodically upon increasing the chain length of the macrocyclic ring. All the nickel(II) complexes show two irreversible one electron oxidation waves at anodic region. The oxidation potential of the complexes shift towards anodically upon increasing the chain length of the macrocyclic ring. The catalytic activities of the complexes were observed to be increase with increase the macrocyclic ring size. The observed rate constant values for the catalytic hydrolysis of 4-nitrophenyl phosphate are in the range of 5.85×10(-3) to 9.14×10(-3) min(-1). All the complexes were screened for antimicrobial activity.     

Emulsifier-free emulsion polymerization produces highly charged, monodisperse particles for near infrared photonic crystals

We have developed emulsifier-free, emulsion polymerization recipes for the synthesis of highly charged, monodisperse latex particles of diameters between 500 and 1100 nm. These latexes consist of poly[styrene-(co-2-hydroxyethyl methacrylate)] spherical particles whose surfaces are functionalized with sulfate and carboxylic acid groups. These highly charged, monodisperse particles readily self-assemble into robust, three-dimensionally ordered crystalline colloidal array photonic crystals that Bragg diffract light in the near infrared spectral region. By altering the particle number density, the diffraction wavelength can be tuned from approximately 1000 to approximately 4000 nm.     

Photoelectrical properties of TlGaSe2 single crystals

The spectral distribution of photocurrent (PC) of TlGaSe₂ single crystals in the range of wavelengths between 500 nm and 700 nm possesses a single maximum at 2.04 eV corresponds to the direct energy band gap of this crystal. The PC is enhanced dramatically by pre-illuminations at low temperatures with band gap light. The temperature dependence of PC of the sample investigated in the temperature range from 80 K to 300 K at constant heating rate shows that the overlapping peaks in the PC spectrum are direct reflection of the Thermally Stimulated Current (TSC) associated with the several trapping levels. The PC response is strongly dependent on the degree of occupancy of traps. The wavelength at the maximum of the PC spectrum is found to be dependent on the wavelength scan direction being up or down. The ferroelectric phase transitions of TlGaSe₂ are detected at ∼108 K and ∼118 K in the PC spectrum.     

Characterisation of non-viable whole barley, wheat and sorghum grains using near-infrared hyperspectral data and chemometrics

Undesired germination of cereal grains diminishes process utility and economic return. Pre-germination, the term used to describe untimely germination, leads to reduced viability of a grain sample. Accurate and rapid identification of non-viable grain is necessary to reduce losses associated with pre-germination. Viability of barley, wheat and sorghum grains was investigated with near-infrared hyperspectral imaging. Principal component analyses applied to cleaned hyperspectral images were able to differentiate between viable and non-viable classes in principal component (PC) five for barley and sorghum and in PC6 for wheat. An OH stretching and deformation combination mode (1,920–1,940 nm) featured in the loading line plots of these PCs; this water-based vibrational mode was a major contributor to the viable/non-viable differentiation. Viable and non-viable classes for partial least squares-discriminant analysis (PLS-DA) were assigned from PC scores that correlated with incubation time. The PLS-DA predictions of the viable proportion correlated well with the viable proportion observed using the tetrazolium test. Partial least squares regression analysis could not be used as a source of contrast in the hyperspectral images due to sampling issues.     

Fast separation of hen egg white protein with a phosphorylcholine type zwitterionic ion chromatography stationary phase

In this work,a kind of preparation method of zwitterionic ion chromatography(ZIC) stationary phase modified with phosphorylcholine(PC) was obtained by hydrolyzing after bonding phosphorylcholine dichloride to diol-silica to better explore the characteristics of the PC groups as ZIC stationary phase ligand in simultaneous separation of acidic proteins and basic proteins. The results showed that tw’o kinds of acidic proteins and three kinds of basic proteins can be separated completely,meanwhile,hen egg white was separated and purified and three kinds of egg white components ovalbumin,G2 ovoglobulin and ovotransfemin proteins were separated completely by one single step on PC-ZIC column,the purity of all proteins reached above 95%.PC-ZIC stationary phase was successfully improved with better separation capacity and selectivity than previously reported in this paper.     

TEMPERATURE DEPENDENCE OF THE PHOSPHORESCENCE LIFETIMES OF HETEROGENEOUS TRYPTOPHAN RESIDUES IN GLOBULAR PROTEINS BETWEEN 293 AND 77 K

Abstract— The phosphorescence of five globular proteins containing tryptophan residues was observed in deoxygenated neutral ethylene glycol-phosphate buffer (1:1 by volume) at 293 and 77 K. Their spectral features at 293 K are closely identical to those at 77 K apart from a lack of tyrosine phosphorescence at 293 K. and are independent of the excitation wavelength between 250 and 310 nm. From the present results. it can be concluded that the buried tryptophan residues are the only phosphorescing centers at room temperature. Their phosphorescence lifetimes were measured as a function of temperature in the range from 77 to 293 K. At room temperature, their phosphorescence lifetimes are between about 1 and 500 ms. On the basis of their temperature dependence, the heterogeneous tryptophan environments are discussed in terms of a temperature-activated nonradiative rate. We suggest that the observation of the phosphorescence characteristics of globular proteins containing tryptophan residues buried in the interior of the protein molecule at room temperature is likely to prove useful in probing the protein structure in solution.     

Evidence for two light-induced metastable states in Cl3[Ru(NH3)5NO]H2O

Differential Scanning Calorimetry measurements on irradiated Cl₃[Ru(NH₃)₅NO]H₂O reveal the existence of two light-induced long-lived metastable states SI, SII. Irradiation with light in the spectral range 400–500 nm leads to the excitation of SI. For the first time we report experimental evidence for the state SII in this compound, which can be excited by transferring SI into SII with irradiation of light in the spectral range 1000–1200 nm. The excitation and transfer of the metastable states is described and the exponential decays are evaluated according to Arrhenius' law yielding activation energies of E_A(SI)=0.73(3) eV, E_A(SII)=0.66(3) eV and frequency factors of Z(SI)=1 × 10¹² s⁻¹, Z(SII) = 5 × 10¹² s⁻¹.     

In situ, rapid, and temporally resolved measurements of cellulase adsorption onto lignocellulosic substrates by UV-vis spectrophotometry

This study demonstrated two in situ UV-vis spectrophotometric methods for rapid and temporally resolved measurements of cellulase adsorption onto cellulosic and lignocellulosic substrates during enzymatic hydrolysis. The cellulase protein absorption peak at 280 nm was used for quantification. The spectral interferences from light scattering by small fibers (fines) and particulates and from absorptions by lignin leached from lignocelluloses were corrected using a dual-wavelength technique. Wavelengths of 500 and 255 nm were used as secondary wavelengths for correcting spectral interferences from light scattering and absorption of leached lignin. Spectral interferences can also be eliminated by taking the second derivative of the measured spectra of enzymatic hydrolysate of cellulose or lignocelluloses. The in situ measured cellulase adsorptions in cellulose and lignocellulose suspensions by these two spectrophotometric methods showed general agreement with batch sampling assayed by the Bradford method. The in situ methods not only eliminated tedious batch sampling but also can resolve the kinetics of the initial adsorption process. The measured time-dependent cellulase adsorptions were found to follow pseudo-second-order kinetics.     

Synthesis,characterization, and electroluminescence of novel copolyfluorenes and their applications in white light emission

New copolyfluorenes (PC8OF0–PC8OF50) comprised of 9,9‐dioctylfluorene and jacketed units 2,5‐bis[(5‐octyloxy‐phenyl)‐1,3,4‐ oxadiazole]‐1‐(3,5‐dibromophenyl)‐benzene (35C8) were synthesized by palladium‐catalyzed Suzuki coupling reaction. They were characterized by molecular weight determination, ¹H NMR, elemental analysis, DSC, TGA, absorption and emission spectroscopy, and cyclic voltammetry (CV). These copolymers were readily soluble in common organic solvents and exhibited high glass transition temperature and thermal stability.The copolymer films showed absorption peaks from 381 nm to 351 nm, and PL peaks from 432 nm to 421 nm with a blue shift originated from 35C8 units. Both the HOMO energy levels and LUMO levels changed little as the content of 35C8 units increased (?5.59 eV to ?5.48 eV and ?2.60 eV to ?2.49 eV). Electroluminescent devices: ITO/PEDOT:PSS[poly(ethylenedioxythiophene):polystyrenesulfonate]/polymer/Ca (25 nm)/Ag(80 nm) (a), ITO/PEDOT:PSS/polymer/TPBI [1,3,5‐ tris(N‐phenylbenzimidazol‐2‐yl)benzene](15 nm)/Mg:Ag(10:1, wt)/Ag (b), and ITO/ PEDOT:PSS/PVK[Poly(N‐vinylcarbazole)]/polymer/TPBI(15 nm)/Ca(25 nm)/Ag(80 nm) (c) were fabricated to investigate the influence of jacketed contents and device architectures on emission characteristics. The maximum brightness and current efficiency of the PC8OF25 device (5097.8 cd/m² and 0.484 cd/A) surpassed those of the PC8OF0 device (3122.8 cd/m² and 0.416 cd/A). The EL emissions of PC8OF0 – PC8OF50 were pure blue and low‐energy excimer emission bands were successfully suppressed, indicating that these copolymers could be good candidates for blue light‐emitting materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4555–4565, 2009     

Conjugated polyelectrolytes and neutral polymers with poly(2,7‐carbazole) backbone: Synthesis,characterization, and photovoltaic application

Poly(2,7‐carbazole) neutral polymers (PC‐N, PC‐NOH, and PC‐P) and polyelectrolytes (PC‐NBr and PC‐SO₃Na) with hydrophilic pendant groups of ammonium, phosphonate, and sulfonate were synthesized as interlayers for cathode modifications in bulk‐heterojunction photovoltaic cells (BHJ PVCs). The absorptions of the polymers were determined by the poly(2,7‐carbazole) backbone, showing absorption peaks at ～390 nm for their solutions and films. Because of large intermolecular interactions, excimer emissions with wavelengths higher than 500 nm were found in the photoluminescence spectra of the films of the polymers, which weakened the light emissions of the polymers. PC‐N, PC‐NBr, PC‐NOH, and PC‐P possessed comparable HOMO levels of ?5.23 eV and LUMO levels of ?2.4 eV, but HOMO and LUMO levels of PC‐SO₃Na were up‐lying to ?4.91 and ?2.12 eV, respectively. PC‐N, PC‐NBr, PC‐NOH, and PC‐P were selected to construct thin interlayers in BHJ PVCs with PFO‐DBT35:PCBM = 1:4 as the active layer. Compared with traditional Al cathode, bilayer cathodes with the interlayers showed improvements of open‐circuit voltages and short‐circuit currents of the PVCs. PC‐NOH was the best for the photovoltaic performances and over 20% increase of power conversion efficiency (PCE) was achieved. The bilayer cathodes would have great potential to further elevate PCE of BHJ PVCs with other active layer materials. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Use of multivariate analysis of MIR spectra to study bread staling

Different kinds of bread, stored at constant temperature and at controlled humidity conditions for a week since their manufacturing date, were analysed by Attenuated Total Reflectance-Fourier Transform InfraRed (ATR-FTIR) spectroscopy. The collected spectra were processed by Principal Component Analysis (PCA), in order to evaluate the changes occurring during bread ageing. For the sake of comparison, the 1060-950 cm spectral window has been also investigated by curve-fitting methods. It was observed that the first PC increases monotonically with ageing of samples. Furthermore, the more influential variables on PC1 correspond to spectral regions where are located stretching and bending bands, which are mainly attributed to typical starch bonds vibrations.     

Imaging and SERS Study of the Au Nanoparticles Interaction with HPV and Carcinogenic Cervical Tissues

In this work, gold NPs were prepared by the Turkevich method, and their interaction with HPV and cancerous cervical tissues were studied by scanning electron microscopy, energy-dispersive x-ray spectroscopy, confocal and multiphoton microscopy and SERS. The SEM images confirmed the presence and localization of the gold NPs inside of the two kinds of tissues. The light absorption of the gold NPs was at 520 nm. However, it was possible to obtain two-photon imaging (red emission region) of the gold NPs inside of the tissue, exciting the samples at 900 nm, observing the morphology of the tissues. The infrared absorption was probably due to the aggregation of gold NPs inside the tissues. Therefore, through the interaction of gold nanoparticles with the HPV and cancerous cervical tissues, a surface enhanced Raman spectroscopy (SERS) was obtained. As preliminary studies, having an average of 1000 Raman spectra per tissue, SERS signals showed changes between the HPV-infected and the carcinogenic tissues; these spectral signatures occurred mainly in the DNA bands, potentially offering a tool for the rapid screening of cancer.     

Determination of cesium,manganese and terbium by intracavity laser spectroscopy

The statistical characteristics of the intracavity laser spectrometer are investigated by analysis of cesium in aqueous solutions. The error distribution of measurements is normal. The relative standard deviation of the analysis in the middle of the dynamic range is equal to 9.7%. The intracavity spectral analysis was carried out at low contents of cesium, manganese and terbium in aqueous solutions. The limits of detection are: 5 microg l(-1) (Cs), 20 microg l(-1) (Mn) and 1000 microg l(-1) (Tb). Owing to the high spectral resolution of the spectrometer used the hyperfine structure of the thallium absorption line (535.05 nm) was recorded.