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A GA-based stacking algorithm for predicting soil organic matter from vis-NIR spectral data
摘要： It has been demonstrated that diffuse reflectance spectroscopy in the visible and near-infrared (vis–NIR) can be exploited to predict chemical and physical soil properties. Immense soil spectral libraries (SSL) are being developed, therefore more elaborate tools that capitalize on contemporary knowledge and techniques need to be established to provide accurate predictions. In this paper, we propose a novel genetic algorithm-based stacking model that makes synergetic use of multiple models developed from different pre-processed spectral sources (termed L1 models). This is a form of ensemble learning where multiple hypotheses are combined to create a more robust and more accurate ensemble hypothesis. The genetic algorithm automatically defines the configuration of the stacked model, by selecting the best cooperating subset of the initial models. Our methodology was tested on the newly developed GEO-CRADLE SSL to predict soil organic matter (SOM). Results showed that the accuracy of prediction of the proposed method ( =0.76, and ratio of performance to inter quartile range RPIQ=2.22) was better than the one attained by the best L1 model ( =0.65, RPIQ=1.93). This approach can thus be effectively utilized to enhance the predictions of soil properties in small and large soil spectral libraries alike.
关键词： model stacking,North Africa,GEO-CRADLE,vis–NIR spectroscopy,soil spectroscopy,Middle East,Balkans
更新于2025-09-10 09:29:36
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The Effect of In-Vivo Collagen Cross-Linking Procedure on the Material of Intracorneal Ring Segments
摘要： The material of Intracorneal Rings Segments (ICRS) has seemed to be polymerized after the absorption of Riboflavin and UV illumination in laboratory settings. This study aimed to assess the potential impact of in-vivo corneal crosslinking (CXL) on the chemical composition of ICRS. Within this contex, three ICRS samples (S1, S2 and S3) were extracted from patients' cornea, which formerly had undergone CXL treatment. Alterations on the chemical structure of PMMA rings were studied using Ultraviolet-Visible (UV-Vis) spectroscopy and Fourier Transform-Infrared (FT-IR) spectroscopy. An extracted ICRS from a patient who didn’t underwent CXL treatment, was also used as reference (S0). UV-Vis spectroscopy didn't identify any change in the specimens S1, S2 and S3. Nevertheless, FT-IR spectroscopic analysis showed alterations in the spectra of ICRS material of samples S1, S2 and S3, mainly at the 2800 to 3200 cm-1 spectral region [modification in band intensities of CH2 (2850 cm-1 and 2925 cm-1) and CH3 (2950cm-1)]. In conclusion, our results suggest crosslinking reaction in ICRS material after in-vivo CXL treatment. This should be taken into consideration prior to any CXL treatment of post ICRS implanted cornea.
关键词： FT-IR spectroscopy,Corneal crosslinking,INTACS,UV-Vis spectroscopy,Keratoconus
更新于2025-09-10 09:29:36
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Spectral Methods in Transition Metal Complexes || Electronic Spectroscopy
摘要： The electronic spectrum covers the range from 200 to 800 nm of the electromagnetic spectrum: 200–400 nm is the ultraviolet region and 400–800 nm is the visible region. Hence, the electronic spectrum is also known as the UV-Vis spectrum. The major application of this spectrum to metal complexes is the determination of the geometry of the complex. In order to arrive at this application, we must understand Term Symbols ?rst. If we want to understand these concepts, selection rules, and transitions, we must have a clear understanding of the concepts of the symmetry of molecules, the symmetry elements, symmetry operations, point groups of molecules, character tables, direct product concepts, and so on. Hence, we will discuss these concepts before the term symbols.
关键词： UV-Vis spectrum,symmetry elements,electronic spectrum,character tables,direct product,Term Symbols,symmetry,metal complexes,point groups,geometry,symmetry operations
更新于2025-09-10 09:29:36
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Photoluminescence of Metal-Imidazolate complexes with Cd(II), Zn(II), Co(II) and Ni(II) cation nodes and 2-methylimidazole organic linker
摘要： A rare example of cadmium-based metal-imidazolate framework nanoparticles which exhibits an intense blue luminescence is presented. Other metal-imidazolate complexes (zinc, cobalt and nickel) are also synthesised and these four complexes are characterised for their gas-absorption, photon-absorption and photoluminescent characteristics. This is compared against commercially available Basolite Z1200? and it is shown that the Cd-based nanoparticles exhibit and intense luminescence, better than the commercial product. These results reveal that these materials might be a good luminescent sensor for detection of absorbed, small molecules.
关键词： photoluminescence,metal organic frameworks,UV-vis,ZIF-8 nanoparticles,CO2 and N2 absorption
更新于2025-09-10 09:29:36
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New Aryl-Substituted 2,2′-Bithiophenes: Synthesis, Optoelectronic Properties and DFT Studies
摘要： New Aryl-Substituted 2,2’-Bithiophenes: Synthesis, Optoelectronic Properties and DFT Studies. Toreshettahally R. Swaroop,[a, b] Zahra A. Tabasi,[b] Yuming Zhao,*[b] and Paris E. Georghiou*[b] and thien-2-yl-[2, 2’-bithiophen]-5-yl)(thiophen-2-yl) Phenyl- methanones were synthesized by the condensation of 2- thienyldithioester with the corresponding methyl ketones followed by cyclization with 2-bromoacetylthiophene. Also, condensation of 2-thienyldithioester with methyl ketones followed by treatment with methyl iodide gave β-thien-2-yl-β- methylthio-α,β-unsaturated ketones, which reacted with the Simmons-Smith reagent to give corresponding 4-phenyl- and thien-2-yl-2,2’-bithiophenes. The optoelectronic properties of these bithiophene derivatives were studied by UV-Vis absorption, fluorescence spectroscopy and cyclic voltammetry. The lowest-energy conformations of these new compounds in the ground and first excited states, the electronic origins of their UV-Vis absorption and fluorescence emission bands, and (FMO) properties were related frontier molecular orbital elucidated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Furthermore, these aryl-substituted bithiophenes were treated with anhydrous ferric chloride to undergo oxidative polymerization, and the fluorescence properties of the resulting polymeric products are also reported herein.
关键词： Thiophenes,UV-vis,Fluorescence,TD-DFT,Oligothiophenes
更新于2025-09-10 09:29:36
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Complementary nature of voltabsorptiometric, nanogravimetric and in situ conductance results for the interpretation of conducting polymers’ redox transformation
摘要： During the last decade the hyphenation of in situ spectrovoltammetry and a.c. conductance techniques has been realized and used for the redox transformation process of conducting polymers. Since charge carriers can be identified spectrally, the simultaneous monitoring of these two signals may answer the questions, how the name-giving property of this class of polymers is connected to the formation of the charge carriers, moreover, which spectrally distinguishable charge carrier is primarily responsible for the development of the conducting state. In the present work multi-faceted studies on numerous systems are presented to illustrate how results obtained by using different in situ electrochemical techniques can complete each other. Systematic measurements taken on differently substituted polythiophene films showed that combined spectral and conductance changes can be interpreted on the grounds of electrogravimetric observations. On this basis the question, which spectrally distinguishable charge carrier is primarily responsible for the development of the conducting state and why, can be answered by considering the mobility of the doping anion.
关键词： Uv-vis-Nir,Hyphenated mode,In situ conductance measurements,EQCN,Conducting polymer,In situ electrochemical techniques
更新于2025-09-10 09:29:36
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Application of coatings on silver studied with punctual and imaging techniques: from specimens to real cases
摘要： The protection of silver artifacts with a coating of organic material isolating the surface from oxygen and S-bearing gases is still one of the most used techniques for the preservation of silver surfaces. A variety of materials suitable to this purpose are being used in the conservation practice. Among them there are acrylic polymers, nitrocellulose lacquer, microcrystalline wax and combination of them in superimposing layers. They are applied either by brush or, in some cases, by spraying. The first stage in a conservation project is often the cleaning of residuals of old protectives, aimed at making the silver surface free from remnants of yellowish materials and enabling the application of new coatings. Unfortunately, removing aged coatings and applying new ones are “blind” processes, since the techniques available for not invasively monitoring the surface of silver artifacts are punctual and do not allow an overall overview of the surface. This is the case of reflectance FTIR and thickness measurement with the Eddy Current technique, which, apart from being punctual, are tricky to apply to uneven surfaces. In this paper, we aim to show the benefits of using an imaging technique, UV induced VIS luminescence, for monitoring the presence and the distribution of protective coatings on silver surfaces and of combining it with reflectance FTIR and thickness gauge. At first, our study was focused on specimens treated with nitrocellulose, acrylic emulsion and microcrystalline wax. The application of the treatments was studied with UV-induced VIS luminescence as well as with the abovementioned punctual techniques to cross-validate the outcome of each method and to assess their suitability for application on organic protective layers on silver artifacts. In a further stage, UV induced VIS luminescence was applied to a real case, a silver chalice that was treated with nitrocellulose lacquer after cleaning.
关键词： reflectance FTIR,UV-induced VIS luminescence,silver artifacts,protective coatings,Eddy Current technique
更新于2025-09-10 09:29:36
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Sparse NIR Optimization method (SNIRO) to quantify analyte composition with visible (VIS)/near infrared (NIR) spectroscopy (350nm-2500nm)
摘要： Visual-Near-Infra-Red (VIS/NIR) spectroscopy has led the revolution in high-throughput phenotyping methods used to determine chemical and structural elements of organic materials. In the current state of the art, spectrophotometers used for imaging techniques are either very expensive or too large to be used as a field-operable device. In this study we developed a Sparse NIR Optimization method (SNIRO) that selects a pre-determined number of wavelengths that enable quantification of analytes in a given sample using linear regression. We compared the computed complexity time and the accuracy of SNIRO to Marten’s test, to forward selection test and to LASSO all applied to the determination of protein content in corn flour and meat and octane number in diesel using publicly available datasets. In addition, for the first time, we determined the glucose content in the green seaweed Ulva sp., an important feedstock for marine biorefinery. The SNIRO approach can be used as a first step in designing a spectrophotometer that can scan a small number of specific spectral regions, thus decreasing, potentially, production costs and scanner size and enabling the development of field-operable devices for content analysis of complex organic materials.
关键词： Imaging,VIS/NIR spectroscopy,Ulva sp.,Chemometrics,Multivariate Analysis,Diesel Octane Number,seaweeds,Sparse Linear Regression
更新于2025-09-10 09:29:36
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Tea types classification with data fusion of UV–Vis, synchronous fluorescence and NIR spectroscopies and chemometric analysis
摘要： The potential of selected spectroscopic methods - UV-Vis, synchronous fluorescence and NIR as well a data fusion of the measurements by these methods - for the classification of tea samples with respect to the production process was examined. Four classification methods - Linear Discriminant Analysis (LDA), Quadratic Discriminant Analysis (QDA), Regularized Discriminant Analysis (RDA) and Support Vector Machine (SVM) - were used to analyze spectroscopic data. PCA analysis was applied prior to classification methods to reduce multidimensionality of the data. Classification error rates were used to evaluate the performance of these methods in the classification of tea samples. The results indicate that black, green, white, yellow, dark, and oolong teas, which are produced by different methods, are characterized by different UV-Vis, fluorescence, and NIR spectra. The lowest error rates in the calibration and validation data sets for individual spectroscopies and data fusion models were obtained with the use of the QDA and SVM methods, and did not exceed 3.3% and 0.0%, respectively. The lowest classification error rates in the validation data sets for individual spectroscopies were obtained with the use of RDA (12,8%), SVM (6,7%), and QDA (2,7%), for the UV-Vis, SF, and NIR spectroscopies, respectively. NIR spectroscopy combined with QDA outperformed other individual spectroscopic methods. Very low classification errors in the validation data sets - below 3% - were obtained for all the data fusion data sets (SF+UV-Vis, SF+NIR, NIR+UV-Vis combined with the SVM method). The results show that UV-Vis, fluorescence and near infrared spectroscopies may complement each other, giving lower errors for the classification of tea types.
关键词： Fluorescence spectroscopy,Food adulteration,NIR,Teas classification,Multivariate data analysis,Data fusion,UV-Vis
更新于2025-09-10 09:29:36
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Application of visible-near infrared spectroscopy to evaluate the quality of button mushrooms
摘要： The Agaricus bisporus mushroom is one of the most cultivated and consumed mushrooms in the world, thanks to its delicacy, nutritional value and flavour. The quality evaluation of the A. bisporus during the harvest is generally established by a visual check by trained operators. This method complies with the request of the Distribution Channel (DC) to retailers and guarantees very low physical damage to the mushrooms; nevertheless, it is subjective and it does not guarantee the highest quality standard for the consumer. The aim of this study was to test the use of visible/near infrared (vis/NIR) reflectance spectroscopy (400–1000 nm) to objectively evaluate the quality parameters of A. bisporus mushrooms. A total of 167 samples of A. bisporus mushrooms were harvested according to the main DC purchasing standards. The vis/NIR analyses were performed the day of sampling just before the physico-chemical analyses (sizes, firmness, soluble solids content and moisture content) used as reference quality parameters. The vis/NIR spectra were correlated to reference measures in order to build predictive models using the partial least squares regression method. Calculated models gave positive results regarding the prediction of the moisture content (r2 (pred) ? 0.78) and firmness (r2 (pred) ? 0.78). Results of this explorative study could be considered encouraging and demonstrate the applicability of vis/NIR spectroscopy on A. bisporus as a rapid technique (i) to monitor the productive process directly at the company, (ii) to standardize the harvest moment, and (iii) to support DC’s buyers’ choices, nowadays exclusively based on product external characteristics.
关键词： quality,vis/NIR spectroscopy,harvest,reflectance,mushrooms,distribution channel
更新于2025-09-10 09:29:36