研究者詳細 - 土川　覚

論文 - 土川　覚

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Investigation of the effects of tableting parameters on reliable quantitative terahertz spectroscopy 査読有り

Su, Y; Xu, Y; Wang, H; Ma, T; Tsuchikawa, S; Inagaki, T

APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 130 巻 ( 2 ) 2024年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics A: Materials Science and Processing

Particle size ratio, tablet thickness, and compaction pressure are three important tableting parameters that affect the obtained tablet spectrum. In this study, the single-factor test and response surface analysis (RSM) were adopted to examine how these three parameters and their interactions affect the analytical measurements performed over terahertz time-domain spectroscopy (THz-TDS). Tablet samples were composed of a different percent (wt-%) of acetylsalicylic acid within microcrystalline cellulose. Results indicate that change in absorption coefficient was found to be more obvious for a larger particle size ratio. Thinner tablets were sensitive to absorption coefficient effects created as the transmitted THz radiation propagates through the tablet interfaces. Compression pressure has a limited effect on the absorption coefficient. The particle size ratio had the largest effect on the coefficient of correlation of the quantitative regression model, followed by the compaction pressure, and the tablet thickness. In this study, the optimized tableting parameters were determined: tablet thickness of 0.48 mm, particle size ratio of about 1:1, and compaction pressure of 30 MPa. Under this condition, the R2 of the quantitative regression model of acetylsalicylic acid content was 0.971 and 0.998 at the range of acetylsalicylic acid mass fraction between 10 and 90 wt-%, 1 and 30 wt-%, respectively. This study provides a method to effectively reduce the scattering effect of spectral detection of tablets by improving the sample’s properties, to provide a reference for enhancing the reliability and accuracy of quantitative measurements.

DOI： 10.1007/s00339-024-07302-3

Three-dimensional modeling of moisture transport in wood using near-infrared hyperspectral imaging and X-ray computed tomography in conjunction with finite element analysis 査読有り Open Access

Zeng, WP; Fujimoto, T; Inagaki, T; Tsuchikawa, S; Ma, T

JOURNAL OF WOOD SCIENCE 70 巻 ( 1 ) 頁： 9 2024年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Wood Science

In past studies, finite element analysis (FEA) methods have been used to simulate the thermal and moisture coupling of wood. However, challenges remain in achieving high-quality three-dimensional (3D) simulations, mainly because of the heterogeneous and complex structure of wood and its difficult-to-detect internal structure, which makes modeling challenging, in addition to the lack of robust experimental techniques to validate simulation results. In this study, the FEA simulation model was refined by combining X-ray computed tomography (CT) and near-infrared hyperspectral imaging (NIR-HSI). CT was used to probe the 3D density of wood, and a novel FEA tetrahedral mesh was constructed based on the results. The NIR-HSI method visualizes the moisture distribution during adsorption and desorption inside the wood. This result is then used to adjust the parameters of the FEA simulation model and as a reference value to evaluate the simulation results. The visualization and simulation results fit well with the theoretical properties. The simulation results can more accurately reflect the spatial distribution and transfer trend of wood moisture at different points in time. Therefore, the CT and NIR-HSI-based 3D heat and moisture-coupled FEA model of wood proposed in this study can be used as a basis for optimizing drying parameters to provide high-quality wood.

DOI： 10.1186/s10086-023-02120-2

Primary assessment of macronutrients in durian (CV Monthong) leaves using near infrared spectroscopy with wavelength selection 査読有り

Phanomsophon, T; Jaisue, N; Worphet, A; Tawinteung, N; Khurnpoon, L; Lapcharoensuk, R; Krusong, W; Pornchaloempong, P; Sirisomboon, P; Inagaki, T; Ma, T; Tsuchikawa, S

SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 304 巻頁： 123398 2024年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

Farmers would be able to regulate fertilization and produce quality durian if they knew the nutrient concentration in durian leaves. A long period of time for traditional nutritional content determination is needed. Therefore, near-infrared spectroscopy is a good method for nondestructive and quick nutrient content evaluation. The leaf sample matrices (fresh leaves, dried ground leaves, and dried ground leaf pellets) were scanned by Fourier transform near-infrared (FT-NIR) with a wavelength of 12,500–3,600 cm−1. Regression models were developed using partial least squares (PLS) with full wavelength, short wavelength, and selected wavelength by successive projections algorithm (SPA). In this study, the model for N and K concentration was acceptable and the prediction was considered good but for P content not had succeeded. As a result, the PLS-SPA model using fresh leaf samples for evaluating N content in durian leaves exhibited performance of r2 = 0.852, SEP = 0.14%, RPD = 2.63 and bias = −0.020%. The PLS-SPA model using dried ground leaf samples for evaluating K content in durian leaves exhibited performance of r2 = 0.820, SEP = 0.13%, RPD = 2.36 and bias = 0.006%. This research found that it is possible to apply NIR waves to predict N and K concentrations in durian leaves. It is not necessary to predict directly from the wavelengths associated with -N or -K bonds. Instead, NIR can measure them indirectly from the bonding of proteins, which are products formed by N and K. In addition, selecting the wavelength that is related to the value to be measured can produce results that are not significantly different from using full or short wavelengths. These models can assist farmers in rapidly predicting N and K content in durian leaves for immediate fertilizer adjustment.

DOI： 10.1016/j.saa.2023.123398

Classification of the Crosslink Density Level of Para Rubber Thick Film of Medical Glove by Using Near-Infrared Spectral Data 査読有り Open Access

Jongyingcharoen, JS; Howimanporn, S; Sitorus, A; Phanomsophon, T; Posom, J; Salubsi, T; Kongwaree, A; Lim, CH; Phetpan, K; Sirisomboon, P; Tsuchikawa, S

POLYMERS 16 巻 ( 2 ) 2024年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Polymers

Classification of the crosslink density level of para rubber medical gloves by using near-infrared spectral data combined with machine learning is the first time reported in this paper. The spectra of medical glove samples with different crosslink densities acquired by an ultra-compact portable MicroNIR spectrometer were correlated with their crosslink density levels, which were referencely evaluated by the toluene swell index (TSI). The machine learning protocols used to classify the 3 groups of TSI were specified as less than 80% TSI, 80–88% TSI, and more than 88% TSI. The 80–88% TSI group was the group in which the compounded latex was suitable for medical glove production, which made the glove specification comply with the requirements of customers as indicated by the tensile test. The results show that when comparing the algorithms used for modeling, the linear discriminant analysis (LDA) developed by 2nd derivative spectra with 15 k-best selected wavelengths fairly accurately predicted the class but was most reliable among other algorithms, i.e., artificial neural networks (ANN), support vector machines (SVM), and k-nearest neighbors (kNN), due to higher prediction accuracy, precision, recall, and F1-score of the same value of 0.76 and no overfitting or underfitting prediction. This developed model can be implemented in the glove factory for screening purposes in the production line. However, deep learning modeling should be explored with a larger sample number required for better model performance.

DOI： 10.3390/polym16020184

Application of Near-Infrared Spectroscopy to Forest and Wood Products 査読有り

Tsuchikawa, S; Inagaki, T; Ma, T

CURRENT FORESTRY REPORTS 9 巻 ( 6 ) 頁： 401 - 412 2023年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Current Forestry Reports

Purpose of Review: Forest and wood products are often characterized by a uniformity of quality attributes, which necessitates the development of rapid and non-destructive quality evaluation methods to ensure their optimal quality. Near-infrared spectroscopy (NIRS) represents a highly suitable approach for the characterization of organic compounds, and is generally combined with sophisticated multivariate analysis methods. This review article presents a range of scientific and technical reports showcasing the successful use of NIRS for evaluating forest and wood products, mainly published within the past 5 years. Recent Findings: Continuous advancements in spectral imaging techniques and the integration of big-data analytics have greatly enhanced the capabilities of NIR instrumentation, enabling its widespread application across diverse fields. Although NIR spectral imaging methods do have some limitations when it comes to online grading, they can still be used to test small quantities of samples at a batch level. Moreover, the ever-increasing use of handheld devices has made NIRS easily accessible. Summary: We aim to provide a summary of new research in basic spectroscopic research, integrating the improvements of spectral imaging methods and big-data analytics. Furthermore, low-cost and portable devices have been produced, enabling remote analysis and further expanding the scope of NIRS applications. Looking forward, we anticipate that continued advancements in this field will enable even wider applications of NIRS for online or at-line quality monitoring in diverse fields.

DOI： 10.1007/s40725-023-00203-3

Characteristics of Resonance Sound in a Circular Saw Enclosure 査読有り Open Access

Takeyama, K; Yokochi, H; Nishio, S; Tsuchikawa, S

BIORESOURCES 18 巻 ( 4 ) 頁： 8473 - 8483 2023年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：BioResources

Several studies have been conducted to reduce the idling noise of circular saws because the sound level is extremely high and harms the environment. However, conventional noise suppression technology only controls the vibrations of the circular saw itself, whereas idling noise can be generated when the air inside the enclosure is resonant. In this study, the relationship between the rotational speeds of the circular saw blade and the frequencies of the resonance sound when the circular saw blade is running idle in an enclosure was examined. Additionally, the sound pressure modes and frequencies of the air in the enclosure were analyzed using the finite element method of acoustic analysis. The results showed that resonance sound was generated only when the circular saw blade was enclosed. The frequencies of the resonance sound generated by a circular saw blade made of acrylic plastic were the same as those generated by a steel saw blade. The resonance sound was generated regardless of the outer diameter of the circular saw blade. The peak resonant frequencies formed a step-like line during the analysis in which the rotational speed of the saw blade was steadily increased.

DOI： 10.15376/biores.18.4.8473-8483

Thermal behavior of heat-treated wood using two-dimensional correlation of near-infrared spectroscopy and differential scanning calorimetry 査読有り

Mahdiyanti, SH; Inagaki, T; Ridho, MR; Marsoem, SN; Tsuchikawa, S

WOOD SCIENCE AND TECHNOLOGY 57 巻 ( 6 ) 頁： 1485 - 1506 2023年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Wood Science and Technology

Heat treatment of wood can decrease its heat capacity and thermal transitions, which are thermal behavior properties of wood. A calorimetric study that highlights the thermal behavior of the molecular mobility of materials is necessary to investigate the thermal degradation of wood. Furthermore, combining it with a nondestructive measurement technique would widen its scope of applicability, especially for wood in service or historical wood that cannot be altered or damaged by invasive methods. Neolamarckia cadamba (Roxb.) Bosser, also known as burflower-tree, a tropical fast-growing hardwood species that has become popular for light-construction works in the past decade, is treated at 90, 120, and 150 ℃ for a duration of 8 h to 3.5 months, scheduled logarithmically. Near-infrared spectroscopy and differential scanning calorimetry (DSC) were used to measure the chemical changes and thermal behavior of the wood before and after heat treatment. Two-dimensional correlation spectroscopy (2DCOS) analysis was then applied to assess the NIR second-derivative spectra and DSC thermograms. The results showed that 2DCOS analysis could assess NIR second-derivative spectra and DSC thermograms under careful observation, as DSC thermograms comprise both qualitative and quantitative information. It provides a new point of view in the non-destructive analysis of wood thermal degradation.

DOI： 10.1007/s00226-023-01506-1

Review of near infrared hyperspectral imaging applications related to wood and wood products 査読有り

Schimleck, L; Ma, T; Inagaki, T; Tsuchikawa, S

APPLIED SPECTROSCOPY REVIEWS 58 巻 ( 9 ) 頁： 585 - 609 2023年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Spectroscopy Reviews

Hyperspectral imaging is a technique that combines spectroscopy and imaging. Originally utilized in the 1980’s by the remote sensing community it is now utilized in a wide variety of applications. Spectral imaging was first used for the detection of compression wood in the late 1990’s and since that time research focused on wood and wood products has steadily increased with a variety of applications reported. While there are several reviews of wood related research utilizing near infrared spectrometers a comprehensive summary of wood—hyperspectral imaging research is lacking. Near infrared hyperspectral imaging systems (NIR-HSI) typically have a wavelength range of 900–1700 nm, whereas short-wave infrared hyperspectral imaging (SWIR-HSI) systems range from 1000 to 2500 nm. We provide a detailed account of the various studies that have been published utilizing both camera types.

DOI： 10.1080/05704928.2022.2098759

Validation study on light scattering changes in kiwifruit during postharvest storage using time-resolved transmittance spectroscopy 査読有り Open Access

Ma, T; Inagaki, T; Tsuchikawa, S

SCIENTIFIC REPORTS 13 巻 ( 1 ) 頁： 16556 2023年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Scientific Reports

Visible and near-infrared spectroscopy has been well studied for characterizing the organic compounds in fruit and vegetables from pre-harvest to late harvest. However, due to the challenge of decoupling of optical properties, the relationship between the collected samples’ spectral data and their properties, especially their mechanical properties (e.g., firmness, hardness, and resilience) is hard to understand. This study developed a time-resolved transmittance spectroscopic method to validate the light scattering changing characteristics in kiwifruit during shelf-life and in cold storage conditions. The experimental results demonstrated that the reduced scattering coefficient (μs′) of 846 nm inside kiwifruit decreased steadily during postharvest storage and is more evident under shelf-life than in cold storage conditions. Moreover, the correlation between the μs′ and the storage time was confirmed to be much higher than that using the external color indexes measured using a conventional colorimeter. Furthermore, employing time-resolved profiles at this single wavelength, an efficacious mathematical model has been successfully formulated to classify the stages of kiwifruit softening, specifically early, mid-, and late stages. Notably, classification accuracies of 84% and 78% were achieved for the shelf-life and cold storage conditions, respectively.

DOI： 10.1038/s41598-023-43777-5

Fit-free analysis of fluorescence lifetime imaging data using chemometrics approach for rapid and nondestructive wood species classification 査読有り

Ma, T; Inagaki, T; Tsuchikawa, S

HOLZFORSCHUNG 77 巻 ( 9 ) 頁： 724 - 733 2023年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Holzforschung

Conventional fluorescence spectroscopy has been suggested as a valuable tool for classifying wood species rapidly and non-destructively. However, because it is challenging to conduct absolute emission intensity measurements, fluorescence analysis statistics are difficult to obtain. In this study, another dimension of fluorescence, that is, fluorescence lifetime, was further evaluated to address this issue. A time-resolved fluorescence spectroscopic measurement system was first designed, mainly using a streak camera, picosecond pulsed laser at 403 nm, and a spectroscope, to collect the fluorescence time-delay (FTD) profiles and steady-state fluorescence intensity (FI) spectra simultaneously from 15 wood species. For data analysis, principal component analysis was used to "compress"the mean-centered FTD and FI spectra. Then, support vector machine classification analysis was utilized to train the wood species classification model based on their principal component scores. To avoid overfitting, ten-fold cross-validation was used to train the calibration model using 70 % of the total samples, and the remaining 30 % hold-out validation was used to test its reproducibility. The cross-validation accuracies were 100 % (5 softwoods) and 96 % (10 hardwoods), with test-validation accuracies of 96 % and 89 %.

DOI： 10.1515/hf-2023-0017

その他リンク： https://www.degruyter.com/document/doi/10.1515/hf-2023-0017/pdf

Development of a sensitivity-enhanced chlorophyll fluorescence lifetime spectroscopic method for nondestructive monitoring of fruit ripening and postharvest decay 査読有り

Ma, T; Inagaki, T; Tsuchikawa, S

POSTHARVEST BIOLOGY AND TECHNOLOGY 198 巻 2023年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Postharvest Biology and Technology

Nondestructive monitoring of the environmental changes around fluorescent molecules in postharvest fruit is highly informative for monitoring their ripening and early decay process. In this study, a time-resolved laser-induced fluorescence (TRLIF) spectroscopic system, including a streak camera, spectrometer, and 403 nm picosecond-pulsed laser, was first developed. Then, representative pigments in photosynthesis (chlorophyll a, chlorophyll b, and carotenoids liquid samples) were initially measured and studied to determine whether the developed TRLIF spectroscopic system could produce the characteristics of chlorophyll fluorescence decay traces. Finally, the same approach was tested to monitor the ripening and early decay processes of each three samples of avocado and strawberry. The overall findings demonstrated that the fluorescence lifetime (FLT) of the fruit samples declined steadily during the shelf-life storage. For the avocados samples, the average FLT loss at the wavelength range of 706–749 nm decreased by approximately 23 % and 31 % at 1 and 2 d under shelf-life storage, respectively. For the strawberry samples, the average FLT loss at the wavelength range of 631–706 nm decreased by approximately 22 %, 46 %, 68 %, and 73 % at 0.5, 1, 1.5, and 2 d under the same shelf-life storage condition. This study indicates that the developed TRLIF spectroscopic method is potentially robust and accurate for assessing the ripening and early decay process of various climacteric and non-climacteric fruit.

DOI： 10.1016/j.postharvbio.2022.112231

Visualization of Sugar Content Distribution of White Strawberry by Near-Infrared Hyperspectral Imaging 査読有り Open Access

Seki, H; Ma, T; Murakami, H; Tsuchikawa, S; Inagaki, T

FOODS 12 巻 ( 5 ) 2023年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Foods

In this study, an approach to visualize the spatial distribution of sugar content in white strawberry fruit flesh using near-infrared hyperspectral imaging (NIR-HSI; 913–2166 nm) is developed. NIR-HSI data collected from 180 samples of “Tochigi iW1 go” white strawberries are investigated. In order to recognize the pixels corresponding to the flesh and achene on the surface of the strawberries, principal component analysis (PCA) and image processing are conducted after smoothing and standard normal variate (SNV) pretreatment of the data. Explanatory partial least squares regression (PLSR) analysis is performed to develop an appropriate model to predict Brix reference values. The PLSR model constructed from the raw spectra extracted from the flesh region of interest yields high prediction accuracy with an RMSEP and (Formula presented.) values of 0.576 and 0.841, respectively, and with a relatively low number of PLS factors. The Brix heatmap images and violin plots for each sample exhibit characteristics feature of sugar content distribution in the flesh of the strawberries. These findings offer insights into the feasibility of designing a noncontact system to monitor the quality of white strawberries.

DOI： 10.3390/foods12050931

Colour Modification of Wood by Dry Thermal Treatment between 90 <sup>o</sup>C and 200 <sup>o</sup>C 査読有り Open Access

Preklet E., Tolvaj L., Tsuchikawa S., Varga D.

Acta Silvatica et Lignaria Hungarica 19 巻 ( 1 ) 頁： 9 - 20 2023年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Acta Silvatica et Lignaria Hungarica

The colour modification effect of dry thermal treatment was studied in black locust (Robinia pseudoacacia L.), poplar (Populus x euramericana cv. Pannonia), Scots pine (Pinus sylvestris L.), spruce (Picea abies Mill.) and larch (Larix decidua L.) species in the temperature range 90-200 °C. Colour data were presented and evaluated in the CIE L*a*b* coordinate system. All thermal treatments applied altered the wood colour throughout the entire cross section regardless of the treatment temperature. At lower temperatures, wood extractives played a decisive role in colour change. The degradation products of hemicelluloses were the major determinant of the change in lightness at 200°C. Redness change in percentage showed much greater alteration than the yellowness and the lightness change. Spruce presented the greatest chromaticity coordinate (a* and b*) alteration among the investigated species. Changes in redness and yellowness followed the Arrhenius law during the investigated dry thermal treatments confirming that the temperature dependence of these colour parameters is exponential for wood material.

DOI： 10.37045/aslh-2023-0001

Experimental study and three-dimensional modeling of moisture transport in wood by means of near-infrared hyperspectral imaging coupled with a heat and mass transfer simulation method 査読有り

Ma, T; Morita, G; Inagaki, T; Tsuchikawa, S

HOLZFORSCHUNG 76 巻 ( 8 ) 頁： 699 - 710 2022年8月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Holzforschung

Substantial efforts have been undertaken for visualizing and simulating the characteristics of water movement in wood. However, three-dimensional (3D) thermo-hygric simulations still pose challenges, not only because wood has a heterogeneous microstructure that results in complex computational models but also because there is a lack of proper experimental techniques to support and validate the model constructions. In this study, the moisture distribution in wood during the water adsorption and desorption processes was first visualized using a near-infrared hyperspectral imaging (NIR-HSI) method that has high resolution, sensibility, and stability. Then, based on the moisture visualization results, the main parameters of a mass transfer simulation code were varied. The visualization and simulation results were confirmed to match well with the main characteristics; e.g., drying speed was slower in the wood parts with higher densities. Additionally, there was a relatively large gradient over the surface layer of the wood samples as the drying progressed, whereas this was not an obvious feature in the water adsorption process. Hence, this study proposes that the NIR-HSI method can be combined with thermo-hygric and 3D simulation model construction. Such an approach provides the basis for optimizing drying conditions and providing high-quality wood products.

DOI： 10.1515/hf-2021-0203

Cognitive spectroscopy for the classification of rice varieties: A comparison of machine learning and deep learning approaches in analysing long-wave near-infrared hyperspectral images of brown and milled samples 査読有り国際共著 Open Access

Onmankhong, J; Ma, T; Inagaki, T; Sirisomboon, P; Tsuchikawa, S

INFRARED PHYSICS & TECHNOLOGY 123 巻頁： 104100 - 104100 2022年6月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Infrared Physics and Technology

Rapid and non-destructive detection of genuine Thai Jasmine rice (Khao Dawk Mali 105 (KDML105)) from Pathum Thani1 (PTT1) and Phitsanulok2 (PSL2) under either milled or brown conditions is required to disrupt fraudulent. This study aimed to resolve this real issue using long-wave near infrared hyperspectral imaging (NIR-HSI) coupled with machine learning and deep learning approaches. The best classification accuracy for the milled rice was achieved using the spectral imaging-based analysis on the NIR-HSI data with selected wavelength, approximately 95% for the test set either by convolutional neural network or support vector machine (SVM), whereas for the brown rice, the SVM model based on the averaged NIR spectra could achieve the best classification accuracy of 95.4%. It suggests the chemical component difference and its spatial distribution in the milled rice could contribute higher classification accuracy. Additionally, the surface bran effects of brown rice could be reduced by using averaged spectral data coupled with the SVM method.

DOI： 10.1016/j.infrared.2022.104100

Comparative Performance of NIR-Hyperspectral Imaging Systems 招待有り査読有り国際共著

Ma Te, Schimleck Laurence, Dahlen Joseph, Yoon Seung-Chul, Inagaki Tetsuya, Tsuchikawa Satoru, Sandak Anna, Sandak Jakub

Foundations 2022年6月

Comparative Performance of NIR-Hyperspectral Imaging Systems 招待有り査読有り国際共著

Ma Te, Schimleck Laurence, Dahlen Joseph, Yoon Seung-Chul, Inagaki Tetsuya, Tsuchikawa Satoru, Sandak Anna, Sandak Jakub

Foundations 2022年6月

Production of Nanocellulose Film from Abaca Fibers 査読有り国際共著 Open Access

Lapuz, AR; Tsuchikawa, S; Inagaki, T; Ma, T; Migo, V

CRYSTALS 12 巻 ( 5 ) 2022年5月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Crystals

Abaca fibers were subjected to a TEMPO mediated oxidation to extract nanocellulose on a 500 L capacity locally fabricated reactor. A yield of 46.7% white gel material with 2.23% solid content was obtained from an overnight reaction. Transmission electron microscopy scan of the white gel material confirms the production of relatively short highly individualized cellulose nanofibril (CNF) as the diameter of abaca fiber was reduced from 16.28 µm to 3.12 nm with fiber length in the range of 100 nm to 200 nm. Nanocellulose film was prepared using air drying (CNF-VC) and vacuum oven drying (CNF-OD). The effect of CNF concentration on the physical, morphological, thermal and mechanical properties were evaluated. FTIR spectra showed cellulose I spectra between abaca fiber with both the CNF-VC film and CNF-OD film with two distinct peaks at 1620 cm−1 and 1720 cm−1 attributed to the carboxyl group resulting from the TEMPO oxidation. In addition, the carboxyl group decreases in thermal stability of cellulose. Moreover, the XRD scan showed a decrease in crystallinity index of CNF films compared to abaca fibers. CNF-VC film showed the highest tensile strength at 0.4% concentration with 88.30 MPa, while a 89.72 MPa was observed for CNF-OD film at 0.8% concentration.

DOI： 10.3390/cryst12050601

Terahertz time-domain spectroscopy as a novel tool for crystallographic analysis in cellulose: cellulose I to cellulose II, tracing the structural changes under chemical treatment 査読有り Open Access

Wang, H; Kataoka, H; Tsuchikawa, S; Inagaki, T

CELLULOSE 29 巻 ( 6 ) 頁： 3143 - 3151 2022年4月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Cellulose

Terahertz time-domain spectroscopy (THz-TDS) has expanded possibilities in cellulose crystallography research, as THz radiation detects most intermolecular vibrations and responds to the phonons of crystalline lattices. In this study, we traced the transformation of the cellulose crystalline lattice from cellulose I to cellulose II by THz-TDS and X-ray powder diffraction. Cellulose II was obtained by treating cellulose I with NaOH of different concentrations (0 wt%–20 wt%, at 2 wt% intervals). The THz absorption coefficient spectra of cellulose II showed three characteristic peaks (at 1.32 THz, 1.76 THz, and 2.77 THz). The THz absorption coefficient spectra of cellulose II treated with 20-wt% NaOH and cellulose I without NaOH treatment were fitted by a seventh-order Fourier series. Thus, the THz absorption coefficient spectra of samples treated with NaOH of other concentrations could be considered a combination of these two fitted profiles of cellulose I and cellulose II, multiplied by different coefficients. Furthermore, the coefficients could reflect the relative contents of cellulose I and cellulose II in the samples.

DOI： 10.1007/s10570-022-04493-x

Application of near-infrared spectroscopy to agriculture and forestry 査読有り

Tsuchikawa, S; Ma, T; Inagaki, T

ANALYTICAL SCIENCES 38 巻 ( 4 ) 頁： 635 - 642 2022年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Analytical Sciences

Depending on the uniformity of the quality attribute within agricultural products, there is often a need to develop non-destructive and efficient evaluation methods to assure their qualities. Near-infrared spectroscopy (NIRS) is a well-suited method to characterize organic compounds, particularly when coupled with multivariate analysis methods. This review article introduces scientific and technical reports using the NIRS to evaluate food, agriculture, and forest products. Overall, basic spectroscopic research is continuously progressing; indeed, in combination with big-data information technology and spectral imaging techniques, material analysis is improving to maximize performance. Portable and low-cost devices have also been designed and produced, enabling remote analysis. Future advancements are expected to result in its applications in even more fields for online or at-line quality monitoring. Graphical abstract: [Figure not available: see fulltext.]

DOI： 10.1007/s44211-022-00106-6

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