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Optimisation of the Quantification of Total Soluble Solids, pH and Titratable Acidity in South African Grape Must using Fourier Transform Mid-infrared Spectroscopy
摘要： Calibration models for Fourier transform mid-infrared (FT-MiR) spectroscopy were developed for the simultaneous quantification of total soluble solids (TSS, measured as °Brix), pH and titratable acidity (TA, expressed as g/L tartaric acid) in South African (SA) grape must. An exploratory data analysis of the FT-MIR spectra of 1170 grape must samples (647 for °Brix, 252 for pH and 271 for TA) was done by principal component analysis, and partial least squares regression was used for the computation of the regression models. The prediction errors for TSS (0.34 °Brix), pH (0.04 units) and TA (0.51 g/L) provided analytical data of satisfactory accuracy. The evaluation of ready-to-use global calibrations to quantify these three parameters in SA samples presented standard error of prediction (SEP) values of 0.46°Brix, 0.10 pH units and 3.13 g/L for TA. After slope and intercept adjustments of the original global calibration algorithms, the SEP values were reduced to 0.38 °Brix, 0.05 pH units and 0.49 g/L for TA. These results show the necessity for optimisation of the global FT-MIR WineScan calibrations to provide a better fit to samples of South African origin. The results demonstrate that FT-MiR spectroscopy is a useful technique for the rapid quantification of major grape must parameters and for quality control purposes in an industrial cellar.
关键词： wine grape chemical analysis,Fourier transform infrared spectroscopy,chemometrics
更新于2025-09-19 17:15:36
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Sensitivity-Enhanced Fourier Transform Mid-Infrared Spectroscopy Using a Supercontinuum Laser Source
摘要： Fourier transform infrared (FT-IR) spectrometers have been the dominant technology in the field of mid-infrared (mid-IR) spectroscopy for decades. Supercontinuum laser sources operating in the mid-IR spectral region now offer the potential to enrich the field of FT-IR spectroscopy due to their distinctive properties, such as high-brightness, broadband spectral coverage and enhanced stability. In our contribution, we introduce this advanced light source as a replacement for conventional thermal emitters. Furthermore, an approach to efficient coupling of pulsed mid-IR supercontinuum sources to FT-IR spectrometers is proposed and considered in detail. The experimental part is devoted to pulse-to-pulse energy fluctuations of the applied supercontinuum laser, performance of the system, as well as the noise and long-term stability. Comparative measurements performed with a conventional FT-IR instrument equipped with a thermal emitter illustrate that similar noise levels can be achieved with the supercontinuum-based system. The analytical performance of the supercontinuum-based FT-IR spectrometer was tested for a concentration series of aqueous formaldehyde solutions in a liquid flow cell (500 mm path length) and compared with the conventional FT-IR (130 mm path length). The results show a four-times-enhanced detection limit due to the extended path length enabled by the high brightness of the laser. In conclusion, FT-IR spectrometers equipped with novel broadband mid-IR supercontinuum lasers could outperform traditional systems providing superior performance, e.g., interaction path lengths formerly unattainable, while maintaining low noise levels known from highly stable thermal emitters.
关键词： Mid-infrared spectroscopy,mid-IR,supercontinuum laser source,Fourier transform infrared spectroscopy,FT-IR
更新于2025-09-16 10:30:52
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Polarization Dependent Reflectivity and Transmission for Cd1-Xznxte/GaAs(001) Epifilms in the Far-Infrared and Near-Infrared to Ultraviolet Region
摘要： The results of a comprehensive experimental and theoretical study is reported to empathize the optical properties of binary GaAs, ZnTe, CdTe and ternary Cd1-xZnxTe (CZT) alloys in the two energy regions: (i) far-infrared (FIR), and (ii) near-infrared (NIR) to ultraviolet (UV). A high resolution Fourier transform infrared spectrometer is used to assess the FIR response of GaAs, ZnTe, CdTe and CZT alloys in the entire composition 1.0 ≥ x ≥ 0 range. Accurate model dielectric functions are established appositely to extort the optical constants of the binary materials. The simulated dielectric functions are meticulously appraised in the FIR → NIR → UV energy range by comparing them against the existing spectroscopic FTIR and ellipsometry data. These outcomes are expended eloquently for evaluating the polarization dependent reflectivity R(λ) and transmission T(λ) spectra of ultrathin CZT/GaAs (001) epifilms. A reasonably accurate assessment of the CZT film thickness by reflectivity study has offered a credible testimony for characterizing any semiconducting epitaxially grown nanostructured materials of technological importance.
关键词： Dielectric functions,Fourier transform infrared spectroscopy,Transmission,Reflectivity,Ellipsometry,Epilayers
更新于2025-09-16 10:30:52
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2125. Staphylococcus Species Identification by Fourier Transform Infrared (FTIR) Spectroscopic Techniques: A Cross-Lab Study
摘要： Staphylococcus aureus is well known to be associated with atopic dermatitis. Recent studies also report S. aureus presence in lesional skin of squamous cell carcinoma (SCC) and its precursor lesion, actinic keratosis (AK). Therefore, it is of potential clinical interest to monitor skin S. aureus colonization on AK lesions. Fourier transform infrared (FTIR) spectroscopy is a cost-effective, nondestructive, and reagent-free technique for rapid microbial identification. It is based on the use of spectral databases developed with well-characterized strains in conjunction with the application of multivariate statistical analysis to elaborate classification models. In the present cross-lab study, spectral databases containing FTIR spectra of over 1000 staphylococcal isolates obtained from reference and clinical microbiology laboratories across Canada were employed in the FTIR spectroscopic identification of Staphylococcus spp. isolated from AK, SCC and perilesional skin of patients at the Princess Alexandra Hospital Dermatology Clinic in Brisbane, Australia.
关键词： atopic dermatitis,actinic keratosis,squamous cell carcinoma,microbial identification,Staphylococcus aureus,Fourier transform infrared spectroscopy
更新于2025-09-16 10:30:52
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Chemical analysis of in vivo–irradiated dentine of head and neck cancer patients by ATR-FTIR and Raman spectroscopy
摘要： Objectives To evaluate the effect of in vivo radiotherapy on the chemical properties of human dentine by Fourier-transform infrared spectroscopy (FTIR) and Raman analysis. Materials and methods Chemical composition was evaluated comparing control and irradiated group (n = 8). Irradiated teeth were obtained from radiotherapy patients subjected to fractionated X-ray radiation of 1.8 Gy daily totaling 72 Gy. The teeth were sectioned according to the type of dentine (crown or root dentine), obtaining 3-mm dentine cervical slices. The analyzed parameters by FTIR and Raman spectroscopies were mineral/matrix ratio (M:M), carbonate/mineral ratio (C:M), amide I/amide III ratio, and amide I/CH2 ratio. Raman also calculated the phosphate and carbonate crystallinity. Results FTIR revealed that M:M had a decrease in both factors (p = 0.008; p = 0.043, respectively) and root dentine showed a lower C:M in the irradiated group (p = 0.003). Raman revealed a higher phosphate crystallinity and a lower carbonate crystallinity in crown dentine of irradiated group (p = 0.021; p = 0.039). For amide I/amide III, the irradiated showed a lower ratio when compared to the control group (FTIR p = 0.002; Raman p = 0.017). For amide I/CH2, the root dentine showed a higher ratio than the crown dentine in both methods (p < 0.001). Conclusions Radiotherapy altered the chemical composition of human dentine. The exchange of phosphate-carbonate ions in the hydroxyapatite and higher concentration of organic components was found after radiotherapy. Clinical relevance The increased risk of radiation-related caries in patients undergoing head and neck radiotherapy is due not only to salivary, dietary, and microbiological changes but also to changes in tooth chemical composition.
关键词： Radiotherapy,Raman spectroscopy,Head and neck cancer,Fourier-transform infrared spectroscopy,Dentine
更新于2025-09-09 09:28:46
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First vibrational investigations of N <sub/>2</sub> O–H <sub/>2</sub> O, N <sub/>2</sub> O–(H <sub/>2</sub> O) <sub/>2</sub> , and (N <sub/>2</sub> O) <sub/>2</sub> –H <sub/>2</sub> O complexes from the far to the near-infrared spectral region by neon matrix isolation and <i>ab initio</i> calculations
摘要： We present for the first time the investigation of water molecules complexed with dinitrogen monoxide, two abundant molecules in atmosphere, in solid neon using Fourier transform infrared (IR) spectroscopy. We identify at least three complexes from concentration effects, N2O–H2O, N2O–(H2O)2, and (N2O)2–H2O, by observation of new absorption bands close to the monomer fundamental modes from the far to the near IR region. We highlight the presence of isomers for the N2O–H2O complex with the help of theoretical calculations at second order M?ller-Plesset (MP2) and coupled-cluster single double triple-F12a/aug-cc-pVTZ levels. The observed frequencies for the N2O–(H2O)2 and (N2O)2–H2O complexes are compared with MP2/aug-cc-pVTZ harmonic data. Anharmonic coupling constants have been derived from the observations of overtones and combination bands.
关键词： ab initio calculations,anharmonic coupling constants,neon matrix isolation,N2O–H2O complexes,Fourier transform infrared spectroscopy
更新于2025-09-09 09:28:46
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Fourier Transform Infrared Spectroscopy: Applications in Medicine
摘要： Fourier transform infrared spectroscopy (FTIR) is rapidly gaining ground in modern clinical research. This technique is useful for understanding a wide variety of applications ranging from characterization and quality control of various compounds to biomedicine. Importantly, biological materials like proteins, carbohydrates, lipids and nucleic acids have unique structures so it is possible to obtain spectral fingerprints corresponding to their functional groups. FTIR spectroscopic techniques generate an immediate appeal in the field of biology and medicine because of their fast and non-invasive nature. It allows easy visualization of cellular components based on their intrinsic properties and chemical composition. It provides a potential route to screen diagnostic markers for diseases like cancer. FTIR spectroscopy is also considered as a useful tool for analysis of the chemical composition of human calculi. Analysis of stone samples from recurrent stone formers by FTIR may provide a clue to effective prevention of stone recurrence [1]. Fourier transform infrared (FT-IR) spectroscopy has proven to be a fundamental and valuable technique in biology and medicine due to its high sensitivity to detecting changes in the functional groups belonging to tissue components such as lipids, proteins and nucleic acids [2]. Infrared spectra of human and animal tissues could provide information on the molecular structure of tissues. FT-IR has been extensively applied for the determination of a biochemical metabolite in biological fluids. Diagnosis of various types of malignancies such as lung, breast, skin, cervical and colon cancers is already reported in the literature. The spectra are analysed for changes in levels of molecules such as RNA, DNA, phosphates, and carbohydrates. Variation of the RNA/DNA ratio as measured at 1121/1020 cm-1 generally show higher ratio for malignant tissues compared to their non-malignant counterpart. Changes in the spectra of malignant samples were also observed in the symmetric and asymmetric stretching bands of the phosphodiester backbones of nucleic acids, the CH stretching region, the C-O stretching bands of the C-OH groups of carbohydrates and cellular protein residuals, and the pressure dependence of the CH2 stretching mode [3]. The changes in the FTIR spectra correlate to modification of bases and sugars, and redistribution of the H-bond network. The loss/change in the covalent bonds due to damage in the primary, secondary and tertiary structure of nucleic acids can be observed in the spectra. These changes involved the phosphate and C-O stretching bands, the CH stretch region, and the pressure dependence of the CH2 bending and C=O stretching modes. FTIR micro spectroscopy has also been used as a fast diagnostic technique to identify drugs targeting specific molecular pathways causing chronic myeloid leukaemia. Chemometric data analysis was used to assess drug compounds in ex vivo cancer cells [4]. Substantial progress has been made in incorporating advances in computational methods into the system to increase the sensitivity of the entire setup, making it an objective and sensitive technique suitable for automation to suit the demands of the medical community. FTIR spectroscopy provides the possibility of obtaining information on molecular composition and structure at the level of single cell within a time-scale of few seconds-minutes and to perform qualitative and quantitative multi-component analyses. It helps in automated pattern recognition and objective classifications of samples with minimal and label-free sample treatment. The technical improvements will progressively increase the number of potential applications of micro FT-IR to cancer research and clinical diagnosis. It may be hoped that the future pre-clinical and clinical trials will include sample evaluation utilizing this technique in order to obtain data necessary to validate the use of micro FT-IR spectroscopy in a clinical context. In fact, this appears to be the most important way to reduce the high level of skepticism of many biologists and pathologists about an old technology that has been designed and improved mainly for applications in clinical diagnosis including cancer research.
关键词： cancer research,biomedicine,clinical diagnosis,Fourier transform infrared spectroscopy,FTIR,clinical research
更新于2025-09-09 09:28:46
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Dense restructuring of amorphous silicon network induced by non-bonded hydrogen
摘要： We con?rmed the presence of non-bonded hydrogens (NBHs) in hydrogenated amorphous silicon (a-Si:H) ?lms, using a combination of multiple techniques (Rutherford backscattering spectrometry/hydrogen forward scattering, Fourier-transform infrared spectroscopy-attenuated total re?ection, and thermal desorption spectrometry). The hydrogen e?usion pro?le of an a-Si:H ?lm with large amounts of NBHs was analyzed in detail. We report the e?ect of NBHs on band structure and electrical conductivity, and we present additional considerations for previous data on number density of silicon, optical bandgap, and vacancy size distribution [J. Non-Cryst. Solids 447, 207 (2016)]. The e?ect of NBHs on the a-Si network is explained by the “dense restructuring model”.
关键词： thermal desorption spectrometry,Rutherford backscattering spectrometry,hydrogenated amorphous silicon,non-bonded hydrogens,dense restructuring model,Fourier-transform infrared spectroscopy
更新于2025-09-09 09:28:46
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Rapid subtyping of pathogenic and nonpathogenic Vibrio parahaemolyticus by fourier transform infrared spectroscopy with chemometric analysis
摘要： Vibrio parahaemolyticus which naturally inhabits marine and estuarine environment represents pathogenic strains (virulence genes tdh or trh positive) and non-pathogenic strains (virulence genes negative). In this study, a rapid method for subtyping pathogenic and non-pathogenic V. parahaemolyticus was established using fourier transform infrared (FTIR) spectroscopy with chemometric analysis. This method targeted three strains of genotypes of V. parahaemolyticus including tdh positive, trh positive and virulence gene-negative (nonpathogenic) V. parahaemolyticus. The FTIR absorption spectra between 1800 and 900 cm?1 highlighted the most distinctive variations and were the most useful for characterizing the three bacteria. The successful differentiation and identification of the three bacteria could be accomplished in less than 1 h by FTIR using principal component analysis (PCA), or another cluster model of hierarchical cluster analysis (HCA). The method was verified by analyzing spiked V. parahaemolyticus fish samples. Furthermore, all of ten clinical isolates of V. parahaemolyticus were identified as tdh-positive, none of the clinical isolates were trh-positive, and all of ten environmental isolates were identified as non-pathogenic by the subtyping method, which were confirmed by PCR assays. All data demonstrated that the newly established subtyping method by FTIR is practical, time-saving, labor-saving, specific and cost-effective, especially suitable for the basic laboratories of CDC and port quarantine departments to perform suiveillance and epidemiological traceability of pathogenic V. parahaemolyticus.
关键词： Pathogenicity,Principal component analysis,Fourier transform infrared spectroscopy,Hierarchical cluster analysis,Vibrio parahaemolyticus,Subtype
更新于2025-09-09 09:28:46
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Development of a radiative transfer model for the determination of toxic gases by Fourier transform–infrared spectroscopy with a support vector machine algorithm
摘要： This report describes a radiative transfer model for Fourier transform-infrared (FT-IR) spectroscopy to create close-to-reality toxic gas spectra by reflecting the unique spectral responses of detectors and using the atmospheric radiative transfer code, MODTRAN. This system can be highly useful in overcoming the limitations for measuring toxic gases in open environments. The emulated gas spectra can be used to train support vector machine (SVM) for chemical gas detection. Its detection performance is evaluated with nerve agents (tabun, sarin, soman, and cyclosarin) and a simulant gas (sulfur hexafluoride) for indoor and outdoor experiments by using two off-the-shelf FT-IR gas detectors. The experimental results show that the proposed SVM algorithm successfully detected and classified targeted gases while reducing false negative and false positive detection rates.
关键词： support vector machine gas detection,Fourier transform infrared remote sensing,support vector machine,hyperspectral imaging,Fourier transform – infrared spectroscopy,stand-off detection
更新于2025-09-04 15:30:14