Pub Date : 2025-04-15DOI: 10.1016/j.vibspec.2025.103806
Feng Zhang, Yang Yang, Dingyue Lian, Lin Li, Suping Zhao, Chaobo Chen
Baseline drift is a key problem in spectral analysis. The resolution of the baseline drift problem sets the stage for future spectral analyses. The baseline correction algorithm previously proposed by scholars may result in inaccurate correction in the presence of spectral overlap peak areas and noise interference, and they all have one or more parameters that need to be optimized by the user. Therefore, an Automatic baseline correction algorithm based on reweighted penalised least squares method for non-sensitive areas(NasPLS) was proposed. First, according to the High solution Transmission Molecular Absorption Database (HITRAN) and actual measurements of hydrocarbon gases, several non-sensitive areas appeared between 400 and 4000 wavenumbers. Then, based on the root mean square error(RMSE) values of the original baseline and the fitted baseline in the non-sensitive areas, the minimum RMSE is found to adapt to updating the smoothing parameters and select the optimal . Finally, the proposed NasPLS method was validated using simulated data and actual measured spectra of methane and ethane, the NasPLS achieves precise baseline correction in the presence of noise interference in simulated data. The results of experimental measurements show that the proposed method can accurately perform baseline corrections in complex situations.
{"title":"An automatic baseline correction method based on reweighted penalised least squares method for non-sensitive areas","authors":"Feng Zhang, Yang Yang, Dingyue Lian, Lin Li, Suping Zhao, Chaobo Chen","doi":"10.1016/j.vibspec.2025.103806","DOIUrl":"10.1016/j.vibspec.2025.103806","url":null,"abstract":"<div><div>Baseline drift is a key problem in spectral analysis. The resolution of the baseline drift problem sets the stage for future spectral analyses. The baseline correction algorithm previously proposed by scholars may result in inaccurate correction in the presence of spectral overlap peak areas and noise interference, and they all have one or more parameters that need to be optimized by the user. Therefore, an Automatic baseline correction algorithm based on reweighted penalised least squares method for non-sensitive areas(NasPLS) was proposed. First, according to the High solution Transmission Molecular Absorption Database (HITRAN) and actual measurements of hydrocarbon gases, several non-sensitive areas appeared between 400 and 4000 wavenumbers. Then, based on the root mean square error(RMSE) values of the original baseline and the fitted baseline in the non-sensitive areas, the minimum RMSE is found to adapt to updating the smoothing parameters and select the optimal <span><math><mi>λ</mi></math></span>. Finally, the proposed NasPLS method was validated using simulated data and actual measured spectra of methane and ethane, the NasPLS achieves precise baseline correction in the presence of noise interference in simulated data. The results of experimental measurements show that the proposed method can accurately perform baseline corrections in complex situations.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103806"},"PeriodicalIF":2.7,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143847646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-13DOI: 10.1016/j.vibspec.2025.103805
Ali I. Al-Mosawi, Shaymaa Abbas Abdulsada
For polymers, including flexible polyvinyl chloride, aging processes play a crucial role in determining their long-term performance and function in various applications, especially those exposed to harsh environmental conditions. Aging effects are analyzed using several tools, including Raman spectroscopy, which is an effective tool for detecting molecular and structural changes in the polymer structure, providing a detailed analytical picture of the degradation behavior as a result of aging. The present study investigates the effect of aging on the structural properties of flexible PVC, taking into account the effect of sample thickness on the results of Raman spectroscopy. The results of 2 and 4 mm thick flexible PVC samples produced by extrusion, immediately after production and after one year of production, after being stored at room temperature without being exposed to harsh external conditions were analyzed to study natural aging. The characteristic Raman peaks associated with plasticizer leaching, chain splitting, and oxidation, as well as the SEM images, were analyzed and the obtained results correlated with the sample thickness. Thicker samples showed a lower rate of detectable chemical changes in the polymer structure, attributed to slower oxygen diffusion and lower chlorine release rate compared to thinner samples exposed to the same environmental conditions. Therefore, it is essential to consider the sample thickness factor in Raman spectroscopy analyses, as it greatly affects the sensitivity and interpretation of the results.
{"title":"Effect of aging on Raman spectroscopy analyses for flexible polyvinyl chloride","authors":"Ali I. Al-Mosawi, Shaymaa Abbas Abdulsada","doi":"10.1016/j.vibspec.2025.103805","DOIUrl":"10.1016/j.vibspec.2025.103805","url":null,"abstract":"<div><div>For polymers, including flexible polyvinyl chloride, aging processes play a crucial role in determining their long-term performance and function in various applications, especially those exposed to harsh environmental conditions. Aging effects are analyzed using several tools, including Raman spectroscopy, which is an effective tool for detecting molecular and structural changes in the polymer structure, providing a detailed analytical picture of the degradation behavior as a result of aging. The present study investigates the effect of aging on the structural properties of flexible PVC, taking into account the effect of sample thickness on the results of Raman spectroscopy. The results of 2 and 4 mm thick flexible PVC samples produced by extrusion, immediately after production and after one year of production, after being stored at room temperature without being exposed to harsh external conditions were analyzed to study natural aging. The characteristic Raman peaks associated with plasticizer leaching, chain splitting, and oxidation, as well as the SEM images, were analyzed and the obtained results correlated with the sample thickness. Thicker samples showed a lower rate of detectable chemical changes in the polymer structure, attributed to slower oxygen diffusion and lower chlorine release rate compared to thinner samples exposed to the same environmental conditions. Therefore, it is essential to consider the sample thickness factor in Raman spectroscopy analyses, as it greatly affects the sensitivity and interpretation of the results.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103805"},"PeriodicalIF":2.7,"publicationDate":"2025-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-09DOI: 10.1016/j.vibspec.2025.103804
Lu Tian , Yankun Li , Mengsha Zhang
In spectral modelling analysis, multicollinearity problems among the spectral variables are prevalent, which may reduce the accuracy of the analysis result. To reduce the effect of multicollinearity between variables in classification analysis, a new strategy of variable selection named as multicollinearity reduction-based variable selection (MR-based VS) is proposed. Characteristic variables were selected based on inter-class significant difference and intra-class correlation evaluation, which reduced data multicollinearity and ensured the selected variables were more relevant to the categories. It was combined with supervised pattern recognition methods of least squares discrimination analysis (PLS-DA) and uncorrelated linear discriminant analysis (ULDA) for the identification of the red wine and olive oil from different geographical origins. The results show that compared with the full-spectrum model and the traditional successive projection algorithm (SPA) variable screening model, the MR-based VS strategy reduces the multicollinearity between variables while ensuring the maximum difference among the different classes, as a result, it obtained the superior classification results. Therefore, MR-based VS can effectively extract categorical features, eliminate redundant information, and improve model interpretability, which shows potential for enhancing the ability of the spectral qualitative analysis model in different fields.
{"title":"A variable selection method based on multicollinearity reduction for food origin traceability identification","authors":"Lu Tian , Yankun Li , Mengsha Zhang","doi":"10.1016/j.vibspec.2025.103804","DOIUrl":"10.1016/j.vibspec.2025.103804","url":null,"abstract":"<div><div>In spectral modelling analysis, multicollinearity problems among the spectral variables are prevalent, which may reduce the accuracy of the analysis result. To reduce the effect of multicollinearity between variables in classification analysis, a new strategy of variable selection named as multicollinearity reduction-based variable selection (MR-based VS) is proposed. Characteristic variables were selected based on inter-class significant difference and intra-class correlation evaluation, which reduced data multicollinearity and ensured the selected variables were more relevant to the categories. It was combined with supervised pattern recognition methods of least squares discrimination analysis (PLS-DA) and uncorrelated linear discriminant analysis (ULDA) for the identification of the red wine and olive oil from different geographical origins. The results show that compared with the full-spectrum model and the traditional successive projection algorithm (SPA) variable screening model, the MR-based VS strategy reduces the multicollinearity between variables while ensuring the maximum difference among the different classes, as a result, it obtained the superior classification results. Therefore, MR-based VS can effectively extract categorical features, eliminate redundant information, and improve model interpretability, which shows potential for enhancing the ability of the spectral qualitative analysis model in different fields.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103804"},"PeriodicalIF":2.7,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-07DOI: 10.1016/j.vibspec.2025.103803
Ahmed M. Ibrahim, Lamiaa A. Hassan
The burgeoning global pharmaceutical market has witnessed a concurrent surge in counterfeit drug proliferation, particularly in developing countries. Counterfeit antibiotics pose a significant threat to public health, potentially leading to treatment failures, antibiotic resistance, and even fatalities. This study presents an innovative independent testing protocol employing Raman spectroscopy and attenuated total reflection infrared spectroscopy (ATR-IR) for the rapid and accurate detection of counterfeit antibiotic vials. These rapid, eco-friendly, and non-destructive techniques enable the acquisition of critical information about the analyzed samples. However, while ATR-IR preserves the chemical composition and structural integrity of the sample, physical contact with the ATR crystal may prevent complete sample recovery. The combination of ATR-IR and Raman spectroscopy leverages their distinct analytical principles ATR-IR detecting polar asymmetric vibrations (dipole moment variations) and Raman identifying symmetric vibrations (polarizability changes) to provide a robust and reliable solution for detecting counterfeit antibiotics. Both Raman spectroscopy and ATR-IR demonstrated exceptional precision and specificity of 100 %, underscoring the model remarkable reliability in counterfeit classification (all counterfeit samples were successfully rejected). Fluorescence backgrounds in Raman spectroscopy were mitigated by employing a 1064 nm laser wavelength, enhancing its applicability for complex matrices. Our Independent Testing Protocol presents a promising solution to the complex issue of counterfeit antibiotic vial detection. By synergizing the strengths of Raman spectroscopy and ATR-IR, we achieve a comprehensive and reliable assessment of antibiotic vials, thereby contributing to patient safety and public health protection.
{"title":"Ensure the authenticity of antibiotic vials: An independent testing protocol using attenuated total reflection infrared spectroscopy and Raman spectroscopy","authors":"Ahmed M. Ibrahim, Lamiaa A. Hassan","doi":"10.1016/j.vibspec.2025.103803","DOIUrl":"10.1016/j.vibspec.2025.103803","url":null,"abstract":"<div><div>The burgeoning global pharmaceutical market has witnessed a concurrent surge in counterfeit drug proliferation, particularly in developing countries. Counterfeit antibiotics pose a significant threat to public health, potentially leading to treatment failures, antibiotic resistance, and even fatalities. This study presents an innovative independent testing protocol employing Raman spectroscopy and attenuated total reflection infrared spectroscopy (ATR-IR) for the rapid and accurate detection of counterfeit antibiotic vials. These rapid, eco-friendly, and non-destructive techniques enable the acquisition of critical information about the analyzed samples. However, while ATR-IR preserves the chemical composition and structural integrity of the sample, physical contact with the ATR crystal may prevent complete sample recovery. The combination of ATR-IR and Raman spectroscopy leverages their distinct analytical principles ATR-IR detecting polar asymmetric vibrations (dipole moment variations) and Raman identifying symmetric vibrations (polarizability changes) to provide a robust and reliable solution for detecting counterfeit antibiotics. Both Raman spectroscopy and ATR-IR demonstrated exceptional precision and specificity of 100 %, underscoring the model remarkable reliability in counterfeit classification (all counterfeit samples were successfully rejected). Fluorescence backgrounds in Raman spectroscopy were mitigated by employing a 1064 nm laser wavelength, enhancing its applicability for complex matrices. Our Independent Testing Protocol presents a promising solution to the complex issue of counterfeit antibiotic vial detection. By synergizing the strengths of Raman spectroscopy and ATR-IR, we achieve a comprehensive and reliable assessment of antibiotic vials, thereby contributing to patient safety and public health protection.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103803"},"PeriodicalIF":2.7,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-04DOI: 10.1016/j.vibspec.2025.103802
Aftab Ansari , D. Mohanta
This work reports Raman analysis of zircon-to-scheelite partial phase conversion encountered in GdVO4 nanosystem with Eu3+ around permissible substitutional doping. To be specific, among the Raman modes featured, the A1g mode is attributed to O-V-O vibration while B2 g represents the translatory vibrational mode (∼258 cm−1) attributed to the Eu–O stretching. The intense high-frequency mode, ν2 = 880 cm–1 would describe stretching internal vibration in the tetrahedral [VO4]3- anionic group for an ideal zircon-type conformation with tetragonal symmetry. Importantly, at room temperature Raman studies of GdVO4 nanosystem, the overlap of two Raman active modes namely, A1g (scissoring) and B2g (twisting) characterize scheelite-type characteristics in the nanosystem under study. Incorporation of Eu3+ in the system resulted in enhancing the intensity of the scheelite-type characteristics due to possible localized phase transition around Eu3+ sites in the matrix. The observed scheelite-type signal enhancement and consequently partial zircon lattice to scheelite lattice conversion due to inclusion of Eu3+ doping (1–7 %) has been highlighted and analyzed emphasizing manifested modes in detail.
{"title":"Raman signature of partial zircon to scheelite-type phase conversion in GdVO4 nanosystem due to structural disordering induced by Eu3+ inclusions","authors":"Aftab Ansari , D. Mohanta","doi":"10.1016/j.vibspec.2025.103802","DOIUrl":"10.1016/j.vibspec.2025.103802","url":null,"abstract":"<div><div>This work reports Raman analysis of <em>zircon</em>-to-<em>scheelite</em> partial phase conversion encountered in GdVO<sub>4</sub> nanosystem with Eu<sup>3+</sup> around permissible substitutional doping. To be specific, among the Raman modes featured, the <em>A</em><sub>1g</sub> mode is attributed to O-V-O vibration while <em>B</em><sub>2 g</sub> represents the translatory vibrational mode (∼258 cm<sup>−1</sup>) attributed to the Eu–O stretching. The intense high-frequency mode, <em>ν</em><sub>2</sub> = 880 cm<sup>–1</sup> would describe stretching internal vibration in the tetrahedral [VO<sub>4</sub>]<sup>3-</sup> anionic group for an ideal <em>zircon-</em>type conformation with tetragonal symmetry. Importantly, at room temperature Raman studies of GdVO<sub>4</sub> nanosystem, the overlap of two Raman active modes namely, <em>A</em><sub>1g</sub> (scissoring) and <em>B</em><sub>2g</sub> (twisting) characterize <em>scheelite</em>-type characteristics in the nanosystem under study. Incorporation of Eu<sup>3+</sup> in the system resulted in enhancing the intensity of the <em>scheelite</em>-type characteristics due to possible localized phase transition around Eu<sup>3+</sup> sites in the matrix. The observed <em>scheelite</em>-type signal enhancement and consequently partial <em>zircon</em> lattice to <em>scheelite</em> lattice conversion due to inclusion of Eu<sup>3+</sup> doping (1–7 %) has been highlighted and analyzed emphasizing manifested modes in detail.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103802"},"PeriodicalIF":2.7,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, we evaluated the changes in near-infrared (NIR) spectra of heavy MgO (100 % MgO; H_MgO) fine granules formulations when stored under humidified conditions. The H_MgO formulations are often mixed with other powdered formulations in clinical practice. In all H_MgO formulations, the peaks at approximately 7350 cm⁻¹ and 7150 cm⁻¹ increased, whereas the peak at approximately 7300 cm⁻¹ decreased depending on the storage period under humidified conditions. Furthermore, slight enhancement of the peaks around 7250 cm⁻¹ and 7200 cm⁻¹ was also observed. These peak changes are attributed to the three-dimensional structure of magnesium hydroxide (Mg(OH)₂) produced by humidification. Subsequently, we evaluated the changes in the NIR spectrum of H_MgO after mixing with 10 % water. The time required for the peak change to appear was shorter than that for storage under humidified conditions. Furthermore, the peaks around 7350 cm⁻¹ , 7250 cm⁻¹ , and 7150 cm⁻¹ were clearly enhanced, and the peak around 7300 cm⁻¹ disappeared immediately after the addition of water. These results suggest that although Mg(OH)₂ is produced when H_MgO is mixed with water, the rate and mechanism of production differ from those observed under humidified storage. The presence of Mg(OH)₂ generated by humidified storage or by mixing with water may affect the stability and water solubility of concomitant pharmaceutical formulations that are sensitive to an alkaline environment. The findings of this study provide useful insights from both fundamental and medical perspectives, and they suggest that NIR spectroscopy, which allows rapid and non-destructive measurements, is effective for these evaluations.
{"title":"Pharmaceutical evaluation of magnesium oxide fine granule formulation for conversion to magnesium hydroxide owing to humidification by near-infrared spectroscopy","authors":"Yoshihisa Yamamoto , Mayo Mitani , Toshiro Fukami , Tatsuo Koide","doi":"10.1016/j.vibspec.2025.103801","DOIUrl":"10.1016/j.vibspec.2025.103801","url":null,"abstract":"<div><div>In this study, we evaluated the changes in near-infrared (NIR) spectra of heavy MgO (100 % MgO; H_MgO) fine granules formulations when stored under humidified conditions. The H_MgO formulations are often mixed with other powdered formulations in clinical practice. In all H_MgO formulations, the peaks at approximately 7350 cm⁻¹ and 7150 cm⁻¹ increased, whereas the peak at approximately 7300 cm⁻¹ decreased depending on the storage period under humidified conditions. Furthermore, slight enhancement of the peaks around 7250 cm⁻¹ and 7200 cm⁻¹ was also observed. These peak changes are attributed to the three-dimensional structure of magnesium hydroxide (Mg(OH)₂) produced by humidification. Subsequently, we evaluated the changes in the NIR spectrum of H_MgO after mixing with 10 % water. The time required for the peak change to appear was shorter than that for storage under humidified conditions. Furthermore, the peaks around 7350 cm⁻¹ , 7250 cm⁻¹ , and 7150 cm⁻¹ were clearly enhanced, and the peak around 7300 cm⁻¹ disappeared immediately after the addition of water. These results suggest that although Mg(OH)₂ is produced when H_MgO is mixed with water, the rate and mechanism of production differ from those observed under humidified storage. The presence of Mg(OH)₂ generated by humidified storage or by mixing with water may affect the stability and water solubility of concomitant pharmaceutical formulations that are sensitive to an alkaline environment. The findings of this study provide useful insights from both fundamental and medical perspectives, and they suggest that NIR spectroscopy, which allows rapid and non-destructive measurements, is effective for these evaluations.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103801"},"PeriodicalIF":2.7,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death worldwide, but our understanding of its pathophysiology is limited. COPD is a debilitating pathology distinguished by diminished pulmonary function and a rapid and persistent decline in overall well-being. Early diagnosis is critical in creating strategies for reducing risk factors and managing COPD consequences. The present study utilised Raman Spectroscopy (RS) to examine serum samples collected from three distinct male cohorts: healthy subjects, asymptomatic smokers, and patients diagnosed with COPD, with a sample size of 10 individuals per group. Given that biochemical alterations take place prior to morphological alterations, RS may be a useful technique for early diagnosis of any pathology. Spectral comparisons revealed a drop in lipid contents and an increase in protein content in the COPD group when compared to the healthy subjects (NR) and asymptomatic smokers (SN) thus showing the potential of RS to get insight into the disease state of COPD. Principal Component Analysis (PCA) and Principal Component-based Linear Discriminant Analysis (PC-LDA) revealed that the healthy group can be stratified from the COPD group with an 80 % accuracy, while the asymptomatic smokers’ group can be distinguished from the COPD group with 70 % accuracy. Multivariate Curve Resolution (MCR) analysis revealed significantly higher lipid component abundance in NR and SN groups, compared to COPD. Further investigation is warranted with well-characterized larger sample size to reduce the spectral misclassification. The results of the RS investigation have the potential to be useful in the early identification of COPD.
{"title":"Serum Raman Spectroscopy – An exploratory study for detection of chronic obstructive pulmonary disease","authors":"Gautam Sharma , Priyanka Jadhav , Sampurno Banerjee , Debarghya Pratim Gupta , Mahesh Padukudru Anand , Koustav Ganguly , Sanjeeva Srivastava , C. Murali Krishna","doi":"10.1016/j.vibspec.2025.103798","DOIUrl":"10.1016/j.vibspec.2025.103798","url":null,"abstract":"<div><div>Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death worldwide, but our understanding of its pathophysiology is limited. COPD is a debilitating pathology distinguished by diminished pulmonary function and a rapid and persistent decline in overall well-being. Early diagnosis is critical in creating strategies for reducing risk factors and managing COPD consequences. The present study utilised Raman Spectroscopy (RS) to examine serum samples collected from three distinct male cohorts: healthy subjects, asymptomatic smokers, and patients diagnosed with COPD, with a sample size of 10 individuals per group. Given that biochemical alterations take place prior to morphological alterations, RS may be a useful technique for early diagnosis of any pathology. Spectral comparisons revealed a drop in lipid contents and an increase in protein content in the COPD group when compared to the healthy subjects (NR) and asymptomatic smokers (SN) thus showing the potential of RS to get insight into the disease state of COPD. Principal Component Analysis (PCA) and Principal Component-based Linear Discriminant Analysis (PC-LDA) revealed that the healthy group can be stratified from the COPD group with an 80 % accuracy, while the asymptomatic smokers’ group can be distinguished from the COPD group with 70 % accuracy. Multivariate Curve Resolution (MCR) analysis revealed significantly higher lipid component abundance in NR and SN groups, compared to COPD. Further investigation is warranted with well-characterized larger sample size to reduce the spectral misclassification. The results of the RS investigation have the potential to be useful in the early identification of COPD.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103798"},"PeriodicalIF":2.7,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-23DOI: 10.1016/j.vibspec.2025.103800
Mingyan Deng , Xinggong Liang , Wanqing Zhang , Shiyang Xie , Shuo Wu , Gengwang Hu , Jianliang Luo , Hao Wu , Zhengyang Zhu , Run Chen , Qinru Sun , Gongji Wang , Zhenyuan Wang
Due to the lack of simple, accurate, and reliable methods, the determination of PMI remains one of the most challenging tasks in forensic pathology, particularly during advanced stages of decomposition. Although numerous methods have been developed for PMI estimation, most are based on animal studies, and the extrapolation of these results to humans remains limited and questionable, providing limited practical utility. To address this gap, we collected a substantial number of human samples and focused on skin tissue, which shows significant potential but has been less extensively studied. ATR-FTIR spectroscopy combined with multiple machine learning algorithms was employed to monitor the spectral changes of skin at different PMI groups. Various algorithms (PLS-R, CLR, PCR, MLR, SVR, XGB-R, and ANN) were utilized to predict PMI. The results demonstrated that the chemical changes in lipids and proteins within postmortem skin tissue exhibited a strong time-dependent pattern. The intensity of lipid absorption peaks in fresh skin tissue was significantly higher than that in decomposed tissue, whereas amide I and II bands demonstrated the opposite trend, initially increasing and subsequently decreasing, which played a crucial role in distinguishing different time points and estimating PMI. The SVR model yielded highly satisfactory results, with the actual PMI showing close alignment with the predicted PMI. The R²CV reached 0.92, while the R²P achieved 0.96, with the RMSE as low as 2.0 days. The RMSEP/RMSECV value of 0.77 indicates the model's strong stability. These findings demonstrate that ATR-FTIR spectroscopy combined with machine learning holds significant potential and practical applicability for PMI estimation in actual forensic cases. This approach not only addresses the research gap in PMI estimation based on human skin samples but also establishes a new research direction in this field.
{"title":"A novel perspective of ATR-FTIR spectroscopy combined with multiple machine learning methods for postmortem interval (PMI) human skin","authors":"Mingyan Deng , Xinggong Liang , Wanqing Zhang , Shiyang Xie , Shuo Wu , Gengwang Hu , Jianliang Luo , Hao Wu , Zhengyang Zhu , Run Chen , Qinru Sun , Gongji Wang , Zhenyuan Wang","doi":"10.1016/j.vibspec.2025.103800","DOIUrl":"10.1016/j.vibspec.2025.103800","url":null,"abstract":"<div><div>Due to the lack of simple, accurate, and reliable methods, the determination of PMI remains one of the most challenging tasks in forensic pathology, particularly during advanced stages of decomposition. Although numerous methods have been developed for PMI estimation, most are based on animal studies, and the extrapolation of these results to humans remains limited and questionable, providing limited practical utility. To address this gap, we collected a substantial number of human samples and focused on skin tissue, which shows significant potential but has been less extensively studied. ATR-FTIR spectroscopy combined with multiple machine learning algorithms was employed to monitor the spectral changes of skin at different PMI groups. Various algorithms (PLS-R, CLR, PCR, MLR, SVR, XGB-R, and ANN) were utilized to predict PMI. The results demonstrated that the chemical changes in lipids and proteins within postmortem skin tissue exhibited a strong time-dependent pattern. The intensity of lipid absorption peaks in fresh skin tissue was significantly higher than that in decomposed tissue, whereas amide I and II bands demonstrated the opposite trend, initially increasing and subsequently decreasing, which played a crucial role in distinguishing different time points and estimating PMI. The SVR model yielded highly satisfactory results, with the actual PMI showing close alignment with the predicted PMI. The R²CV reached 0.92, while the R²P achieved 0.96, with the RMSE as low as 2.0 days. The RMSEP/RMSECV value of 0.77 indicates the model's strong stability. These findings demonstrate that ATR-FTIR spectroscopy combined with machine learning holds significant potential and practical applicability for PMI estimation in actual forensic cases. This approach not only addresses the research gap in PMI estimation based on human skin samples but also establishes a new research direction in this field.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103800"},"PeriodicalIF":2.7,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143724630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-20DOI: 10.1016/j.vibspec.2025.103799
Thomas G. Mayerhöfer , Susanne Pahlow , Uwe Hübner , Jürgen Popp
Using theoretical and experimental transmission, transflection, and attenuated total reflection (ATR) spectra, we investigated how well corresponding absorbance spectra correlate with true absorbance, defined as the absorption index function multiplied by the wavenumber, using poly(methyl methacrylate) layers on CaF2, Si, and gold substrates. To improve correlation, the substrate spectrum is often subtracted from the sample spectrum. A typical example is layers on CaF2, where this approach is sufficient to establish a strong linear correlation. However, in many cases, the substrate spectrum is not a suitable reference for removing unwanted physical contributions, such as substrate-related effects. One such example is layers on Si substrates, where high reflectance causes the spectrum to be dominated by interference fringes. Instead of using the spectrum of an uncoated substrate, one must use the spectrum of a substrate with a non-absorbing layer that has the same refractive index in the transparency region between the MIR and visible spectral regions. For ATR spectra, a simple multiplicative correction based on the wavelength dependence of the penetration depth significantly increases the Pearson coefficient, though not to levels high enough for spectral recognition. To achieve higher accuracy, the Poor Man’s ATR Correction can be employed. For transflection spectra, all relatively simple methods generally fail, and only methods that ultimately determine the optical constant function show promise for success.
{"title":"Exploring correlation in infrared spectroscopy","authors":"Thomas G. Mayerhöfer , Susanne Pahlow , Uwe Hübner , Jürgen Popp","doi":"10.1016/j.vibspec.2025.103799","DOIUrl":"10.1016/j.vibspec.2025.103799","url":null,"abstract":"<div><div>Using theoretical and experimental transmission, transflection, and attenuated total reflection (ATR) spectra, we investigated how well corresponding absorbance spectra correlate with true absorbance, defined as the absorption index function multiplied by the wavenumber, using poly(methyl methacrylate) layers on CaF<sub>2</sub>, Si, and gold substrates. To improve correlation, the substrate spectrum is often subtracted from the sample spectrum. A typical example is layers on CaF<sub>2</sub>, where this approach is sufficient to establish a strong linear correlation. However, in many cases, the substrate spectrum is not a suitable reference for removing unwanted physical contributions, such as substrate-related effects. One such example is layers on Si substrates, where high reflectance causes the spectrum to be dominated by interference fringes. Instead of using the spectrum of an uncoated substrate, one must use the spectrum of a substrate with a non-absorbing layer that has the same refractive index in the transparency region between the MIR and visible spectral regions. For ATR spectra, a simple multiplicative correction based on the wavelength dependence of the penetration depth significantly increases the Pearson coefficient, though not to levels high enough for spectral recognition. To achieve higher accuracy, the Poor Man’s ATR Correction can be employed. For transflection spectra, all relatively simple methods generally fail, and only methods that ultimately determine the optical constant function show promise for success.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103799"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143687699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-19DOI: 10.1016/j.vibspec.2025.103797
Maycom Cezar Valeriano , Antonio Morais Neto , Natalia Lima dos Santos , Antonio Carlos Ferreira Batista , Mónica Benicia Mamián-López
As biodiesel is becoming more important as an alternative and cleaner biofuel in the energy transition, methodologies for monitoring its quality are necessary to guarantee the integrity of engines. One of the most relevant parameters in the quality control routine is oxidative stability, a characteristic related to the effect of oxygen in biodiesel at room temperature during storage. Quantifying the degree of oxidation in biodiesel is essential as undesirable products, such as sediments, polymers, or short-chain fatty acids, can be formed, significantly modifying its biofuel properties. In this work, for the first time, a rapid and non-destructive methodology based on Raman spectroscopy assisted by Partial Least Squares (PLS) regression was developed to quantify the oxidative stability of soy biodiesel by calibrating its Raman spectra against the induction time, monitored through the reference method. This combined strategy allows a fast and environmentally friendly methodology to quantify the induction time. With it, Root Mean Squared Error values for calibration and prediction of 0.2759 and 0.3260 h, respectively, were reached. These values were significantly lower than those reported by other spectroscopic methodologies, showing that merging the biodiesel's highly informative Raman features with the potentiality of chemometric modeling is very promising for rapid routine analyses that can be easily adapted outside the laboratory. Besides, this provides a substantial advancement in biodiesel quality control, considering that its use as a biofuel continuously grows worldwide.
{"title":"Merging Partial Least Squares & Raman spectroscopy to quantify oxidative stability in biodiesel","authors":"Maycom Cezar Valeriano , Antonio Morais Neto , Natalia Lima dos Santos , Antonio Carlos Ferreira Batista , Mónica Benicia Mamián-López","doi":"10.1016/j.vibspec.2025.103797","DOIUrl":"10.1016/j.vibspec.2025.103797","url":null,"abstract":"<div><div>As biodiesel is becoming more important as an alternative and cleaner biofuel in the energy transition, methodologies for monitoring its quality are necessary to guarantee the integrity of engines. One of the most relevant parameters in the quality control routine is oxidative stability, a characteristic related to the effect of oxygen in biodiesel at room temperature during storage. Quantifying the degree of oxidation in biodiesel is essential as undesirable products, such as sediments, polymers, or short-chain fatty acids, can be formed, significantly modifying its biofuel properties. In this work, for the first time, a rapid and non-destructive methodology based on Raman spectroscopy assisted by Partial Least Squares (PLS) regression was developed to quantify the oxidative stability of soy biodiesel by calibrating its Raman spectra against the induction time, monitored through the reference method. This combined strategy allows a fast and environmentally friendly methodology to quantify the induction time. With it, Root Mean Squared Error values for calibration and prediction of 0.2759 and 0.3260 h, respectively, were reached. These values were significantly lower than those reported by other spectroscopic methodologies, showing that merging the biodiesel's highly informative Raman features with the potentiality of chemometric modeling is very promising for rapid routine analyses that can be easily adapted outside the laboratory. Besides, this provides a substantial advancement in biodiesel quality control, considering that its use as a biofuel continuously grows worldwide.</div></div>","PeriodicalId":23656,"journal":{"name":"Vibrational Spectroscopy","volume":"138 ","pages":"Article 103797"},"PeriodicalIF":2.7,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143687079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号