Journal of Spectroscopy The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Simultaneous Quantification of Paracetamol and Caffeine in Powder Blends for Tableting by NIR-Chemometry Sun, 28 May 2017 00:00:00 +0000 Near-infrared spectroscopy (NIRS) is a technique widely used for rapid and nondestructive analysis of solid samples. A method for simultaneous analysis of the two components of paracetamol and caffeine from powder blends has been developed by using chemometry with near-infrared spectroscopy (NIRS). The method development was performed on samples containing 80, 90, 100, 110, and 120% active pharmaceutical ingredients, and near-infrared spectroscopy (NIRS) spectra of prepared powder blends were recorded and analyzed in order to develop models for the prediction of drug content. Many calibration models were applied in order to perform quantitative determination of drug content in powder, and choosing the appropriate number of factors (principal components) proved to be of highly importance for a PLS chemometric calibration. Once the methods were developed, they were validated in terms of trueness, precision, and accuracy. The results obtained by NIRS methods were compared with those obtained by HPLC reference method, and no significant differences were found. Therefore, the NIR chemometry methods were proved to be a suitable tool for predicting chemical properties of powder blends and for simultaneous determination of active pharmaceutical ingredients. Dana Maria Muntean, Cristian Alecu, and Ioan Tomuta Copyright © 2017 Dana Maria Muntean et al. All rights reserved. Corrigendum to “Investigating the Degradability of HDPE, LDPE, PE-BIO, and PE-OXO Films under UV-B Radiation” Tue, 16 May 2017 00:00:00 +0000 A. Martínez-Romo, R. González-Mota, J. J. Soto-Bernal, and I. Rosales-Candelas Copyright © 2017 A. Martínez-Romo et al. All rights reserved. The Clinical Application of Raman Spectroscopy for Breast Cancer Detection Mon, 15 May 2017 00:00:00 +0000 Raman spectroscopy has been widely used as an important clinical tool for real-time in vivo cancer diagnosis. Raman information can be obtained from whole organisms and tissues, at the cellular level and at the biomolecular level. The aim of this paper is to review the newest developments of Raman spectroscopy in the field of breast cancer diagnosis and treatment. Raman spectroscopy can distinguish malignant tissues from noncancerous/normal tissues and can assess tumor margins or sentinel lymph nodes during an operation. At the cellular level, Raman spectra can be used to monitor the intracellular processes occurring in blood circulation. At the biomolecular level, surface-enhanced Raman spectroscopy techniques may help detect the biomarker on the tumor surface as well as evaluate the efficacy of anticancer drugs. Furthermore, Raman images reveal an inhomogeneous distribution of different compounds, especially proteins, lipids, microcalcifications, and their metabolic products, in cancerous breast tissues. Information about these compounds may further our understanding of the mechanisms of breast cancer. Pin Gao, Bing Han, Ye Du, Gang Zhao, Zhigang Yu, Weiqing Xu, Chao Zheng, and Zhimin Fan Copyright © 2017 Pin Gao et al. All rights reserved. Influence of Fractional Differential on Correlation Coefficient between EC1:5 and Reflectance Spectra of Saline Soil Tue, 09 May 2017 00:00:00 +0000 Soil salinization is one of the most serious environmental issues in arid and semiarid area with severe social, economic, and ecological problems. At present, most inversion models are based on raw reflectance spectra or integer differential transform. In this study, we measured the hyperspectral reflectance and EC1:5 of soil samples collected form Ebinur Lake to analyze the influence of fractional differential on correlation coefficient between EC1:5 and reflectance spectra. The results showed that the fractional differential increased sensibly the accuracy for the analysis of the reflectance spectra. The study might provide a new insight for monitoring soil salinity using hyperspectral data, and further researches should be concentrated on physical meaning of fractional differential in hyperspectral data to provide theoretical basis to building, describing, and spreading inversion models. Nan Xia, Tashpolat Tiyip, Ardak Kelimu, Ilyas Nurmemet, Jianli Ding, Fei Zhang, and Dong Zhang Copyright © 2017 Nan Xia et al. All rights reserved. Simultaneous Determination of Four Compounds in a Nelumbo nucifera Seed Embryo by HPLC-DAD Thu, 13 Apr 2017 09:50:40 +0000 Nelumbo nucifera has a variety of biological activities. So it was importantly used as various herbal medicines since traditional times. A simple, fast, and sensitive high-performance liquid chromatographic (HPLC) method was developed in this study for efficient quality control of N. nucifera. Four different compounds, including neferine, 1,2,3,4-tetrahydro-1-[(4-hydroxyphenyl) methyl]-2-methyl-7-isoquinolinol, 1-hydroxy-2-methylpropene, and 3-(prop-1-enyl)benzene-1,2,4,5-tetrol, were simultaneously determined. The four compounds were isolated through a Dionex C18 column by gradient elution with 0.1% TFA-water and methanol. The flow rate was 1.0 mL/min, and the wavelength was detected at 205, 254, 280, and 330 nm. The chromatograms were acquired at 205 nm. The four compounds showed good linear relationships () over five different concentrations, and an average recovery of the method ranged from 96.27% to 108.78%. Through the analysis validation test and application of the method, the optimized conditions verified that it is efficient to isolate the compounds of N. nucifera seed embryos. Gahee Ryu, Jin Bae Weon, Woo Seung Yang, and Choong Je Ma Copyright © 2017 Gahee Ryu et al. All rights reserved. Ultrafast Charge and Triplet State Formation in Diketopyrrolopyrrole Low Band Gap Polymer/Fullerene Blends: Influence of Nanoscale Morphology of Organic Photovoltaic Materials on Charge Recombination to the Triplet State Thu, 13 Apr 2017 00:00:00 +0000 Femtosecond transient absorption spectroscopy of thin films of two types of morphologies of diketopyrrolopyrrole low band gap polymer/fullerene-adduct blends is presented and indicates triplet state formation by charge recombination, an important loss channel in organic photovoltaic materials. At low laser fluence (approaching solar intensity) charge formation characterized by a 1350 nm band (in ~250 fs) dominates in the two PDPP-PCBM blends with different nanoscale morphologies and these charges recombine to form a local polymer-based triplet state on the sub-ns timescale (in ~300 and ~900 ps) indicated by an 1100 nm absorption band. The rate of triplet state formation is influenced by the morphology. The slower rate of charge recombination to the triplet state (in ~900 ps) belongs to a morphology that results in a higher power conversion efficiency in the corresponding device. Nanoscale morphology not only influences interfacial area and conduction of holes and electrons but also influences the mechanism of intersystem crossing (ISC). We present a model that correlates morphology to the exchange integral and fast and slow mechanisms for ISC (SOCT-ISC and H-HFI-ISC). For the pristine polymer, a flat and unstructured singlet-singlet absorption spectrum (between 900 and 1400 nm) and a very minor triplet state formation (5%) are observed at low laser fluence. René M. Williams, Hung-Cheng Chen, Daniele Di Nuzzo, Stephan C. J. Meskers, and René A. J. Janssen Copyright © 2017 René M. Williams et al. All rights reserved. Combined Raman Spectroscopy and Digital Holographic Microscopy for Sperm Cell Quality Analysis Mon, 10 Apr 2017 06:48:33 +0000 The diagnosis of male infertility is vastly complex. To date, morphology, motility, and concentration have been used as key parameters to establish the sperm normality and achieve pregnancy both in natural and in assisted fecundation. However, spermatozoa from infertile men could present a variety of alterations, such as DNA fragmentation, alterations of chromatin structure, and aneuploidy, which have been demonstrated to decrease reproductive capacity of men. Therefore, the ability to see detailed relationships between morphology and physiology in selected spermatozoa with submicrometric resolution in a nondestructive and noninvasive way and within a functional correlated context could be extremely important for the intracytoplasmic sperm injection procedure. In this review, we describe label-free optical spectroscopy and imaging techniques, based on the combination of Raman spectroscopy/imaging with holographic imaging, which are able to noninvasively measure the (bio)chemistry and morphology of sperm cells. We discuss the benefits and limitation of the proposed photonic techniques, with particular emphasis on applications in detection/characterization of sperm cell morphological defects and photodamage, and the identification/sorting of X- and Y-bearing bovine spermatozoa. A. De Angelis, S. Managò, M. A. Ferrara, M. Napolitano, G. Coppola, and A. C. De Luca Copyright © 2017 A. De Angelis et al. All rights reserved. Cavity-Enhanced Spectroscopy in Condensed Phases: Recent Literature and Remaining Challenges Wed, 29 Mar 2017 06:13:22 +0000 Recent developments in the field of cavity-enhanced spectroscopy (CES) on liquid samples are presented. The various experimental approaches to achieving the measurements are summarized, and the limitations of each approach are discussed. I conclude CES is most promising for microscale light absorption measurements on submicroliter volumes of fluid. Jonathan E. Thompson Copyright © 2017 Jonathan E. Thompson. All rights reserved. Detecting the Early Stage of Phaeosphaeria Leaf Spot Infestations in Maize Crop Using In Situ Hyperspectral Data and Guided Regularized Random Forest Algorithm Tue, 28 Mar 2017 06:55:40 +0000 Phaeosphaeria leaf spot (PLS) is considered one of the major diseases that threaten the stability of maize production in tropical and subtropical African regions. The objective of the present study was to investigate the use of hyperspectral data in detecting the early stage of PLS in tropical maize. Field data were collected from healthy and the early stage of PLS over two years (2013 and 2014) using a handheld spectroradiometer. An integration of a newly developed guided regularized random forest (GRRF) and a traditional random forest (RF) was used for feature selection and classification, respectively. The 2013 dataset was used to train the model, while the 2014 dataset was used as independent test dataset. Results showed that there were statistically significant differences in biochemical concentration between the healthy leaves and leaves that were at an early stage of PLS infestation. The newly developed GRRF was able to reduce the high dimensionality of hyperspectral data by selecting key wavelengths with less autocorrelation. These wavelengths are located at 420 nm, 795 nm, 779 nm, 1543 nm, 1747 nm, and 1010 nm. Using these variables (), a random forest classifier was able to discriminate between the healthy maize and maize at an early stage of PLS infestation with an overall accuracy of 88% and a kappa value of 0.75. Overall, our study showed potential application of hyperspectral data, GRRF feature selection, and RF classifiers in detecting the early stage of PLS infestation in tropical maize. Elhadi Adam, Houtao Deng, John Odindi, Elfatih M. Abdel-Rahman, and Onisimo Mutanga Copyright © 2017 Elhadi Adam et al. All rights reserved. Shot-Noise Limited Time-Encoded Raman Spectroscopy Wed, 22 Mar 2017 03:09:29 +0000 Raman scattering, an inelastic scattering mechanism, provides information about molecular excitation energies and can be used to identify chemical compounds. Albeit being a powerful analysis tool, especially for label-free biomedical imaging with molecular contrast, it suffers from inherently low signal levels. This practical limitation can be overcome by nonlinear enhancement techniques like stimulated Raman scattering (SRS). In SRS, an additional light source stimulates the Raman scattering process. This can lead to orders of magnitude increase in signal levels and hence faster acquisition in biomedical imaging. However, achieving a broad spectral coverage in SRS is technically challenging and the signal is no longer background-free, as either stimulated Raman gain (SRG) or loss (SRL) is measured, turning a sensitivity limit into a dynamic range limit. Thus, the signal has to be isolated from the laser background light, requiring elaborate methods for minimizing detection noise. Here, we analyze the detection sensitivity of a shot-noise limited broadband stimulated time-encoded Raman (TICO-Raman) system in detail. In time-encoded Raman, a wavelength-swept Fourier domain mode locking (FDML) laser covers a broad range of Raman transition energies while allowing a dual-balanced detection for lowering the detection noise to the fundamental shot-noise limit. Sebastian Karpf, Matthias Eibl, Wolfgang Wieser, Thomas Klein, and Robert Huber Copyright © 2017 Sebastian Karpf et al. All rights reserved. Using a Spectrofluorometer for Resonance Raman Spectra of Organic Molecules Tue, 21 Mar 2017 00:00:00 +0000 Scattering (Rayleigh and Raman) and fluorescence are two common light signals that frequently occur together, confusing the researchers and graduate students experimenting in molecular spectroscopy laboratories. This report is a brief study presenting a clear discrimination between the two signals mentioned, employing a common spectrofluorometer such as the PerkinElmer LS 55. Even better, the resonance Raman signal of a molecule (e.g., acetone) can be obtained elegantly using the same instrument. Vadivel Masilamani, Hamid M. Ghaithan, Mamduh J. Aljaafreh, Abdullah Ahmed, Reem al Thagafi, Saradh Prasad, and Mohamad S. Alsalhi Copyright © 2017 Vadivel Masilamani et al. All rights reserved. Active Mode Remote Infrared Spectroscopy Detection of TNT and PETN on Aluminum Substrates Tue, 21 Mar 2017 00:00:00 +0000 Two standoff detection systems were assembled using an infrared telescope coupled to a Fourier transform infrared spectrometer, a cryocooled mercury-cadmium telluride detector, and a telescope-coupled midinfrared excitation source. Samples of the highly energetic materials (HEMs) 2,4,6-trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN) were deposited on aluminum plates and detected at several source-target distances by carrying out remote infrared spectroscopy (RIRS) measurements on the aluminum substrates in active mode. The samples tested were placed at 1–30 m for the RIRS detection experiments. The effect of the angle of incidence/collection of the IR beams on the vibrational band intensities and the signal-to-noise ratios (S/N) were investigated. Experiments were performed at ambient temperature. Surface concentrations from 50 to 400 μg/cm2 were studied. Partial least squares regression analysis was applied to the spectra obtained. Overall, RIRS detection in active mode was useful for quantifying the HEMs deposited on the aluminum plates with a high confidence level up to the target-collector distances of 1–25 m. John R. Castro-Suarez, Leonardo C. Pacheco-Londoño, Joaquín Aparicio-Bolaño, and Samuel P. Hernández-Rivera Copyright © 2017 John R. Castro-Suarez et al. All rights reserved. Kinetic Study of Atmospheric Pressure Nitrogen Plasma Afterglow Using Quantitative Electron Spin Resonance Spectroscopy Sun, 19 Mar 2017 00:00:00 +0000 Quantitative electron spin resonance spectroscopy is used to measure nitrogen atom density in atmospheric pressure dielectric barrier discharge afterglow. The experiment shows that oxygen injection into early afterglow increases the nitrogen dissociation in certain parts of the afterglow while it is decreased in the rest of the afterglow. Numerical kinetic modelling supports and explains the experimental data while the best fit provides some a priori unknown parameters such as initial concentrations and rate constants. A. Tálský, O. Štec, M. Pazderka, and V. Kudrle Copyright © 2017 A. Tálský et al. All rights reserved. Comparative Analysis of Optical Signals Emitted by Corona on a Laboratory Model of Transmission Lines Made of Various Materials Wed, 15 Mar 2017 00:00:00 +0000 The paper presents results of comparative analyses of optical signals generated by corona discharges occurring in the vicinity and on the surface of power transmission lines made of five different materials under laboratory conditions. Three aluminium-based materials were chosen: pure aluminium, aluminium with added magnesium, and aluminium with added silicon, and for comparison purposes also, steel-based lines were considered: copper-coated steel and steel with added chromium and nickel. A three-phase triangular arrangement system operating under maximal voltage equal to 110 kV was applied for experimental tests. The optical radiation was registered using a spectrophotometer. During research works, also the influence of corona generation voltage and distance between power lines was investigated. Based on the achieved results, it was stated that the highest corona intensity was found for aluminium-based lines, for both pure aluminium and aluminium with added magnesium and silicon. The lowest corona intensity was observed for chromium- and nickel-alloyed (stainless) steel. Sławomir Krzewiński, Paweł Frącz, Ireneusz Urbaniec, and Tomasz Turba Copyright © 2017 Sławomir Krzewiński et al. All rights reserved. Terahertz Spectroscopy and Brewster Angle Reflection Imaging of Acoustic Tiles Wed, 08 Mar 2017 00:00:00 +0000 A Brewster angle reflection imaging apparatus is demonstrated which is capable of detecting hidden water-filled voids in a rubber tile sample. This imaging application simulates a real-world hull inspection problem for Royal Canadian Navy Victoria-class submarines. The tile samples represent a challenging imaging application due to their large refractive index and absorption coefficient. With a rubber transmission window at approximately 80 GHz, terahertz (THz) sensing methods have shown promise for probing these structures in the laboratory. Operating at Brewster’s angle allows for the typically strong front surface reflection to be minimized while also conveniently making the method insensitive to air-filled voids. Using a broadband THz time-domain waveform imaging system (THz-TDS), we demonstrate satisfactory imaging and detection of water-filled voids without complicated signal processing. Optical properties of the tile samples at low THz frequencies are also reported. Patrick Kilcullen, Mark Shegelski, MengXing Na, David Purschke, Frank Hegmann, and Matthew Reid Copyright © 2017 Patrick Kilcullen et al. All rights reserved. Comprehensive Study of a Handheld Raman Spectrometer for the Analysis of Counterfeits of Solid-Dosage Form Medicines Sun, 05 Mar 2017 09:42:38 +0000 The fight against medicine counterfeiting is a current focus of the pharmaceutical world. Reliable analytical tools are needed to pursue the counterfeiters. Handheld devices present the advantage of providing quick results, with analyses possibly performed on the field. A large number of solid-dosage form medicines have been analyzed with a handheld Raman spectrometer. 33 out of 39 product families could be successfully analysed. The methods were validated with 100% of correct identification. Each product was additionally tested by the methods of the other products and successfully rejected. A second validation was performed using counterfeits, placebos, and generics. All the counterfeits were rejected, with values close to zero. Some generics presented a similar formulation to the brand products and were then identified as such. One placebo was positively identified, showing that low dosage products are difficult to analyze with Raman. Robustness tests were carried out, showing, for instance, that the operator has no influence on the results and that the analyses might be performed through transparent packaging. The discovery mode was also investigated, which proposes the chemical composition of the samples. The results demonstrated that the Raman handheld device is a reliable tool for the field analysis of counterfeits. Klara Dégardin, Aurélie Guillemain, and Yves Roggo Copyright © 2017 Klara Dégardin et al. All rights reserved. Solid-State FTIR Spectroscopic Study of Two Binary Mixtures: Cefepime-Metronidazole and Cefoperazone-Sulbactam Sun, 05 Mar 2017 00:00:00 +0000 The structural information of the pharmaceuticals and insights on the modes of molecular interactions are very important aspects in drug development. In this work, two cephalosporins and antimicrobial combinations, cefepime-metronidazole and cefoperazone-sulbactam, were studied in the solid state using FTIR spectroscopy for the first time. Quantitation of the studied drugs and their binary mixtures was performed by integrating the peak areas of the characteristic well-resolved bands: υ (C=O) band at 1773 cm−1 for cefepime and ring torsion band at 826 cm−1 for metronidazole and υ (C=O) band at 1715 cm−1 for cefoperazone and ring torsion band at 1124 cm−1 for sulbactam. The results of this work were compared with the relevant spectrophotometric reported methods. This study provides data that can be used for the preparative process monitoring of the studied drugs in various dosage forms. Hassan Refat H. Ali, Ramadan Ali, Hany A. Batakoushy, and Sayed M. Derayea Copyright © 2017 Hassan Refat H. Ali et al. All rights reserved. Cell Imaging by Spontaneous and Amplified Raman Spectroscopies Mon, 27 Feb 2017 07:19:09 +0000 Raman spectroscopy (RS) is a powerful, noninvasive optical technique able to detect vibrational modes of chemical bonds. The high chemical specificity due to its fingerprinting character and the minimal requests for sample preparation have rendered it nowadays very popular in the analysis of biosystems for diagnostic purposes. In this paper, we first discuss the main advantages of spontaneous RS by describing the study of a single protozoan (Acanthamoeba), which plays an important role in a severe ophthalmological disease (Acanthamoeba keratitis). Later on, we point out that the weak signals that originated from Raman scattering do not allow probing optically thin samples, such as cellular membrane. Experimental approaches able to overcome this drawback are based on the use of metallic nanostructures, which lead to a huge amplification of the Raman yields thanks to the excitation of localized surface plasmon resonances. Surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS) are examples of such innovative techniques, in which metallic nanostructures are assembled on a flat surface or on the tip of a scanning probe microscope, respectively. Herein, we provide a couple of examples (red blood cells and bacterial spores) aimed at studying cell membranes with these techniques. Giulia Rusciano, Gianluigi Zito, Giuseppe Pesce, and Antonio Sasso Copyright © 2017 Giulia Rusciano et al. All rights reserved. Inhibition Effect of Phosphorus Flame Retardants on the Fire Disasters Induced by Spontaneous Combustion of Coal Tue, 31 Jan 2017 09:13:53 +0000 Coal spontaneous combustion (CSC) generally induces fire disasters in underground mines, thus causing serious casualties, environmental pollution, and property loss around the world. By using six P-containing additives to process three typical coal samples, this study investigated the variations of the self-ignition characteristics of the coal samples before and after treatment. The analysis was performed by combining thermogravimetric analysis/differential scanning calorimetry (TG/DSC) Fourier transform infrared spectrometer (FTIR) and low temperature oxidation. Experimental results showed that P-containing inhibitors could effectively restrain the heat emitted in the combustion of coal samples and therefore the ignition temperature of the coal samples was delayed at varying degrees. The combustion rate of the coal samples was reduced as well. At the temperatures ranging from 50°C to 150°C, the activation energy of the coal samples after the treatment was found to increase, which indicated that the coal samples were more difficult to be oxidized. After being treated with phosphorus flame retardants (PFRs), the content of several active groups represented by the C-O structure in the three coal samples was proved to be obviously changed. This suggested that PFRs could significantly inhibit the content of CO generated by the low temperature oxidation of coal, and the flame-retardant efficiency grew with the increasing temperature. At 200°C, the maximal inhibition efficiency reached approximately 85%. Yibo Tang Copyright © 2017 Yibo Tang. All rights reserved. A Low-Field Temperature Dependent EPR Signal in Terraced MgO:Mn2+ Nanoparticles: An Enhanced Zeeman Splitting in the Wide-Bandgap Oxide Thu, 19 Jan 2017 00:00:00 +0000 Mn2+ ion doping is used as an electron paramagnetic resonance (EPR) probe to investigate the influence of low-coordination structural defects such as step edges at the surface of terraced (001) MgO nanoparticles on the electronic properties. Beside the well-known hyperfine sextet of Mn2+ ions in the cubic crystal field of MgO, an additional EPR feature with a striking nonmonotonous temperature dependent shift of the -factor is observed in terraced nanoparticles in the temperature range from 4 K to room temperature. By linking the difference in the temperature dependence of the Mn2+ sextet intensity in cubic and terraced nanoparticles with the possible s-d exchange shift and enhanced Zeeman splitting we conclude that the novel EPR feature originates from the loosely trapped charge-compensating carriers at the abundant structural defects at the surface of terraced nanoparticles due to their exchange interaction with neighboring Mn2+ ions. Peter V. Pikhitsa, Sukbyung Chae, Seungha Shin, and Mansoo Choi Copyright © 2017 Peter V. Pikhitsa et al. All rights reserved. Experimental Study on the Atomization and Chemiluminescence Characteristics of Ethanol Flame Thu, 19 Jan 2017 00:00:00 +0000 The breakup regime in ethanol diffusion flame under different conditions was studied by the high speed camera system combined with the UV camera system. Spray angle and Weber number (We) were used to represent the change of breakup regime. With the increases of spray angle and We, the breakup mode changes from the Rayleigh-type breakup regime to the superpulsating regime. The reaction area and intensity of ethanol flames under different breakup regimes could be discussed by the distribution. From Rayleigh-type breakup regime to superpulsating breakup regime, the distribution increased and the oxidation-reduction reaction area expanded. At the condition of superpulsating breakup mode, the intensity of was significantly higher than that of other modes. The flame luminous length can be obtained by the emission, and distribution reflects the structure of flame. When the breakup regime changes from the fiber-type breakup regime to the superpulsating regime, the flame luminous length increases suddenly. Qing Zhang, Xudong Song, Qinghua Guo, Yan Gong, Chonghe Hu, and Guangsuo Yu Copyright © 2017 Qing Zhang et al. All rights reserved. A Derivative Spectrometric Method for Hydroquinone Determination in the Presence of Kojic Acid, Glycolic Acid, and Ascorbic Acid Wed, 18 Jan 2017 00:00:00 +0000 A new, simple, and sensitive spectrometric method was developed for hydroquinone (HQ) determination in the presence of other depigmenting agents (kojic acid (KA), glycolic acid (GA), and ascorbic acid (AA)), commonly introduced in skin lightening products. The method is based on the oxidation of the depigmenting agents by potassium dichromate in sulfuric acid medium and subsequent measurement of the amplitude of the first-order derivative absorption spectrum at 268 nm. By applying the zero-crossing method, at this wavelength, the oxidation products of KA, AA, and GA do not interfere in the indirect determination of HQ. Beer’s law was obeyed in the range of 0.22–22 μg·mL−1 HQ, with a detection limit of 0.07 μg·mL−1. The developed method was applied with good results for the first time to the rapid determination of HQ in binary, ternary, and quaternary mixtures, thus proving that it could represent an effective tool for various skin lightening products analyses. Zenovia Moldovan, Dana Elena Popa, Iulia Gabriela David, Mihaela Buleandra, and Irinel Adriana Badea Copyright © 2017 Zenovia Moldovan et al. All rights reserved. Photophysical Properties of Fluorescent Probe Thioflavin T in Crowded Milieu Thu, 12 Jan 2017 07:46:28 +0000 Thioflavin T (ThT) is a widely used fluorescent probe of amyloid fibrils, which accompanies many serious neurodegenerative and other diseases. Until recently, examinations of processes of amyloid fibril formation in vitro were conducted in solutions whose properties were significantly different from those found inside the densely packed cells. Such crowded cellular milieu is typically simulated in vitro using concentrated solutions of inert polymers, which do not usually interact with proteins. However, these crowding agents can have a direct effect on the ThT molecule, and this effect must be taken into account. We examined the influence of PEG-400, PEG-12000, and Dextran-70 on the photophysical properties of ThT. It was shown that these crowding agents caused the red shift of the absorption, fluorescence excitation, and fluorescence spectra of ThT. Under these conditions, the increases of the molar extinction coefficient, fluorescence quantum yield, and excitation lifetime of ThT are also observed. However, these changes are significantly less pronounced than those observed for ThT bound to fibrils. It is concluded that, despite some effects of crowding agents on intrinsic fluorescent properties of ThT, this dye can be used as a probe of structure and formation of amyloid fibrils in crowded milieu in vitro. Natalia P. Rodina, Maksim I. Sulatsky, Anna I. Sulatskaya, Irina M. Kuznetsova, Vladimir N. Uversky, and Konstantin K. Turoverov Copyright © 2017 Natalia P. Rodina et al. All rights reserved. Science Applied for the Investigation of Imperial Gate from Eighteenth Century Wooden Church of Nicula Monastery Wed, 11 Jan 2017 12:12:46 +0000 Part of an indestructible component of any orthodox church, the Imperial Gates represent an important symbol in our cultural heritage. But in many cases the Imperial Gates from the wooden churches were damaged. In order to preserve and restore them, the scientific investigations of the Imperial Gate belonging to Nicula Monastery wooden church were performed by employing nondestructive and destructive methods. The wood essence was established, with its “health” status being investigated by FTIR (Fourier Transform Infrared) spectroscopy and DSC (Differential Scanning Calorimetry) thermal analysis. The painting materials employed by popular artists were determined by FTIR and XRF (X-ray fluorescence) spectroscopy as gypsum, calcite (rear background), lead white (Archangel Clothes), lead-minium (Archangel Clothes, leaf), iron oxide (Imperial Gate frame), malachite (green), Prussian blue (blue), orpiment (yellow), aliphatic, ester, and protein (probably egg yolk degradation products). Using similar colors as in the original artwork (resulting from the scientific investigation of the pigments) a 3D reconstruction has been performed. The restored Imperial Gates are placed in the old Nicula wooden church, being included into a tourist and religious circuit. I. Bratu, Monk Siluan, C. Măruţoiu, I. Kacso, S. Garabagiu, V. C. Măruţoiu, C. Tănăselia, D. Popescu, D. L. Postolache, and D. Pop Copyright © 2017 I. Bratu et al. All rights reserved. Rapid Detection of Pesticide Residues in Chinese Herbal Medicines by Fourier Transform Infrared Spectroscopy Coupled with Partial Least Squares Regression Tue, 27 Dec 2016 12:33:07 +0000 This paper reports a simple, rapid, and effective method for simultaneous detection of cartap (Ca), thiocyclam (Th), and tebufenozide (Te) in Chinese herbal medicines including Radix Angelicae Dahuricae and Liquorices using Fourier transform infrared spectroscopy (FT-IR) coupled with partial least squares regression (PLSR). The proposed method can handle the intrinsic interferences of herbal samples; satisfactory average recoveries attained from near-infrared (NIR) and mid-infrared (MIR) PLSR models were and % for Ca, and % for Th, and and % for Te, respectively. Furthermore, some statistical parameters and figures of merit are fully investigated to evaluate the performance of the two models. It was found that both models could give accurate results and only the performance of MIR-PLSR was slightly better than that of NIR-PLSR in the cases suffering from herbal matrix interferences. In conclusion, FT-IR spectroscopy in combination with PLSR has been demonstrated for its application in rapid screening and quantitative analysis of multipesticide residues in Chinese herbal medicines without physical or chemical separation pretreatment step and any spectral processing, which also implies other potential applications such as food and drug safety, herbal plants quality, and environmental evaluation, due to its advantages of nontoxic and nondestructive analysis. Tianming Yang, Rong Zhou, Du Jiang, Haiyan Fu, Rui Su, Yangxi Liu, and Hanbo Su Copyright © 2016 Tianming Yang et al. All rights reserved. Application of Optical Spectrophotometry for Analysis of Radiation Spectrum Emitted by Electric Arc in the Air Mon, 26 Dec 2016 11:32:31 +0000 This paper presents the results of measurement and analysis of optical radiation emitted by a free burning electric arc. The aim was to determine the application possibilities of optical spectrophotometry for detection of electric arcs. The research works considered electric arc generated with a constant voltage supply between two copper electrodes in the air, carried out under laboratory conditions. A high resolution optical spectrophotometer was used for registration of optical radiation. The analyses involved determination of two dimensionless descriptors obtained for the gathered spectra. Moreover, for each of the registered intensity distributions, the energy values were calculated for three frequency ranges. Based on the measured signals, the possibility of application of spectrophotometry for the optical radiation analysis was confirmed. The analysis indicated that the most energy of optical radiation is detected for the range of 200–780 nm, while above 780 nm almost no optical energy is emitted. Spectrophotometric studies performed in the UV-NIR range are of interest since one can obtain information about the structural defects (at lower wavebands) or impurities and/or point defects (at low energies bands). It was also stated that the obtained descriptors may be applied for diagnosis and identification of electric arc purposes. Michał Kozioł, Daria Wotzka, Tomasz Boczar, and Paweł Frącz Copyright © 2016 Michał Kozioł et al. All rights reserved. Corrigendum to “Background Radiance Estimation for Gas Plume Quantification for Airborne Hyperspectral Thermal Imaging” Mon, 19 Dec 2016 14:55:31 +0000 Ramzi Idoughi, Thomas H. G. Vidal, Pierre-Yves Foucher, Marc-André Gagnon, and Xavier Briottet Copyright © 2016 Ramzi Idoughi et al. All rights reserved. XPS and GDOES Characterization of Porous Coating Enriched with Copper and Calcium Obtained on Tantalum via Plasma Electrolytic Oxidation Mon, 19 Dec 2016 12:31:57 +0000 XPS and GDOES characterizations of porous coatings on tantalum after Plasma Electrolytic Oxidation (PEO) at 450 V for 3 minutes in electrolyte containing concentrated (85%) phosphoric acid with calcium nitrate and copper (II) nitrate are described. Based on the obtained data, it may be concluded that the PEO coating consists of tantalum (Ta5+), calcium (Ca2+), copper (Cu2+  and Cu+), and phosphates (). It has to be pointed out that copper and calcium are distributed throughout the volume. The authors also propose a new model of PEO, based on the derivative of GDOES signals with sputtering time. Krzysztof Rokosz, Tadeusz Hryniewicz, Patrick Chapon, Steinar Raaen, and Hugo Ricardo Zschommler Sandim Copyright © 2016 Krzysztof Rokosz et al. All rights reserved. Light Manipulation by Single Cells: The Case of Diatoms Wed, 14 Dec 2016 11:44:06 +0000 Diatoms are ubiquitous monocellular microalgae, responsible for about 20–25% of the global oxygen produced by photosynthesis. Living in environments where sunlight is not so easily accessible, evolution shaped diatoms in order to exploit light with high efficiency. In particular, diatoms are provided with an external, micro- and nanopatterned silica shell, the frustule, surprisingly similar to artificial photonic crystals and able to manipulate light in many different ways. The present paper reviews the most relevant studies on optical and photonic properties of diatoms that have been performed throughout the last years making use of SEM characterizations, transmittance measurements at different wavelengths, holographic microscopy, Raman spectroscopy and imaging, photoluminescence spectroscopy, and the predictive support of different numerical simulation algorithms. Edoardo De Tommasi Copyright © 2016 Edoardo De Tommasi. All rights reserved. Enamel Based Composite Layers Deposited on Titanium Substrate with Antifungal Activity Mon, 12 Dec 2016 09:02:02 +0000 The goal of this paper was to investigate the antifungal activity of Enamel layers deposited on titanium substrate (Ti-Enamel) and Enamel layers deposited on titanium substrate previously coated with a vinyl polydimethylsiloxane layer (Ti-PDMS-Enamel). The physicochemical properties were also investigated. The Candida albicans biofilm development on the obtained layers was examined after 24 h, 48 h, and 72 h by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) after ethidium bromide staining. A significant inhibition of the fungal adherence and biofilm development was observed on Ti-Enamel layers. The antifungal results demonstrated that the use of new Ti-Enamel composite layers could represent a promising perspective for the prevention of fungal biofilms associated implant infections. S. L. Iconaru, A. M. Prodan, C. S. Turculet, M. Beuran, R. V. Ghita, A. Costescu, A. Groza, M. C. Chifiriuc, P. Chapon, S. Gaiaschi, R. Hristu, G. A. Stanciu, R. Trusca, M. Ganciu, S. M. Raita, N. Vineticu, and C. S. Ciobanu Copyright © 2016 S. L. Iconaru et al. All rights reserved.