研究者詳細 - 土川　覚

論文 - 土川　覚

分割表示 539 件中 41 - 60 件目／全件表示 >>

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

Rapid and nondestructive prediction of firmness, soluble solids content, and pH in kiwifruit using Vis-NIR spatially resolved spectroscopy 査読有り国際共著 Open Access

Ma, T; Zhao, J; Inagaki, T; Su, Y; Tsuchikawa, S

POSTHARVEST BIOLOGY AND TECHNOLOGY 186 巻 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：Postharvest Biology and Technology

This paper reports an evaluation of firmness, soluble solids content (SSC), and acidity (pH) in kiwifruit using a newly designed visible–near-infrared (Vis–NIR) spatially resolved spectroscopic (SRS) system. The system mainly comprises a cost-effective Vis–NIR hyperspectral imaging camera, a halogen light source, and 36 light-receiving silica fibers which were divided into six groups (1, 2, 3, 4, 5, and 10 mm away from the light illumination) used to collect diffusely reflected light from sample surface. During the experiment, time-resolved spectroscopy (TRS) was used to validate the light scattering characteristics at a single wavelength of 846 nm by transmission measurement, which differed from the reflectance measurement of the SRS system. The TRS results show that firmer kiwifruits tended to have a lower transmitted light intensity and a higher full width at half maximum value. The SRS results indicate that the reflected light intensity decreased more with an increased distance from the illumination spot in firmer kiwifruits. The results of the two methods supported the same view, i.e., firmer kiwifruit indicated higher degrees of light scattering inside. Following on, the calibration models for kiwifruit properties were constructed using the SRS data coupled with partial least squares regression analysis. Finally, the prediction accuracies were benchmarked against standard diffuse reflectance spectroscopy using one fiber group position of the same SRS system. The overall results showed the benefits of using the SRS system to predict fruit firmness by enhancing light scattering effects and predicting the SSC required for reducing such effects.

DOI： 10.1016/j.postharvbio.2022.111841

Moisture transport dynamics in wood during drying studied by long-wave near-infrared hyperspectral imaging 査読有り Open Access

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

CELLULOSE 29 巻 ( 1 ) 頁： 133 - 145 2022年1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

The complexities of wood microstructure cause difficulties in understanding water movement characteristics during drying. Here, the water transport dynamics in softwood (Japanese cypress) with different sample lengths (30 mm, 60 mm, and 90 mm) and various drying temperatures (30 °C, 60 °C, and 90 °C) were studied using a rapid and high-resolution moisture content (MC) mapping method based on long-wave near-infrared hyperspectral imaging (NIR-HSI). The observations of this study are as follows: slow drying at approximately 30 °C, the area near the subsurface of the wood samples tends to have higher MC than the central parts during drying, especially in the case of longer wood samples. For drying at higher temperatures, strongly bonded water appeared at the surface areas much earlier, which could easily cause sample deformation and cracking. Overall, the experimental results suggest the capillary effects could play a major role at the first stage of slow drying at fiber level; then, the transfers between bound and free water could play a significant power source in the second drying stage. It is expected that this study will be of help in providing a basis to study and simulate the drying characteristics of cellular and hydrophilic materials.

DOI： 10.1007/s10570-021-04290-y

Near-infrared spectroscopy and hyperspectral imaging can aid in the prediction and mapping of polyploid acacia hybrid wood properties in tree improvement programs 査読有り Open Access

Viet, DD; Ma, T; Inagaki, T; Kim, NT; Tsuchikawa, S

HOLZFORSCHUNG 75 巻 ( 12 ) 頁： 1067 - 1080 2021年12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

Acacia, including Acacia hybrids, are some of the most important species grown as part of the Vietnamese wood industry. Rapid methods to identify the variations in the wood properties of Acacia hybrids however, are a currently lacking and creating limits for their breeding programs. In this study, nine Acacia hybrid clones, including those that were diploid, triploid, and tetraploid were evaluated using near-infrared spectroscopy (NIR) and hyperspectral imaging (HSI). The standard normal variate (SNV) and second derivative (SP2D) were applied to compare the performances of NIR and HSI using partial least square regression. The HSI images were acquired at wavelengths from 1033 to 2230 nm and the SNV and SP2D described the variations in the wood properties. The NIR predicted the wood physical properties better than HSI, while they provided similar predictions for the mechanical properties. The mapping results showed low densities around the pith area and high densities near the bark. They also revealed that the air-dry moisture content changed at different positions within a disk and was dependent on its position within the tree. Overall, NIR and HSI were found to be potential wood property prediction tools, suitable for use in tree improvement programs.

DOI： 10.1515/hf-2021-0024

Measuring the tensile strain of wood by visible and near-infrared spatially resolved spectroscopy 査読有り Open Access

Ma, T; Inagaki, T; Yoshida, M; Ichino, M; Tsuchikawa, S

CELLULOSE 28 巻 ( 17 ) 頁： 10787 - 10801 2021年11月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Cellulose

Strain measurement is critical for wood quality evaluation. Using conventional strain gauges constantly is high cost, also challenging to measure precious wood materials due to the use of strong adhesive. This study demonstrates the correlation between the light scattering degrees inside the wood during tension testing and their macroscopic strain values. A multifiber-based visible-near-infrared (Vis–NIR) spatially resolved spectroscopy (SRS) system was designed to rapidly and conveniently acquire such light scattering changes. For the preliminary experiment, samples with different thicknesses, from 2 to 5 mm, were measured to evaluate the influence of sample thickness. The differences in Vis–NIR SRS spectral data diminished with an increase in sample thickness, suggesting that the SRS method can successfully measure the wood samples' whole strain (i.e., surface and inside). Then, for the primary experiment, 18 wood samples were each prepared with approximately the same sample thickness of 2 mm and 5 mm to construct strain calibration models, respectively. The prediction accuracy of the 2-mm samples was characterized by a determination coefficient (R<sup>2</sup>) of 0.81 with a root mean squared error (RMSE) of 343.54 με for leave-one-out cross-validation; for test validation, the validation accuracy was characterized by an R<sup>2</sup> of 0.76 and an RMSE of 395.35 με. For the validation accuracy of the 5-mm samples, R<sup>2</sup><inf>val</inf> was 0.69 with 440.78 με RMSE<inf>val.</inf> Overall, the presented calibration results of the SRS approach were confirmed to be superior to the standard diffuse reflectance spectroscopy.

DOI： 10.1007/s10570-021-04239-1

その他リンク： https://link.springer.com/article/10.1007/s10570-021-04239-1/fulltext.html

Parameter Optimization of Vibrating and Comb-Brushing Harvesting of <i>Lycium barbarum</i> L. Based on FEM and RSM 査読有り Open Access

Zhao, J; Ma, T; Inagaki, T; Chen, Y; Hu, GR; Wang, ZW; Chen, QY; Gao, ZN; Zhou, JG; Wang, MH; Tsuchikawa, S; Chen, J

HORTICULTURAE 7 巻 ( 9 ) 頁： 286 - 286 2021年9月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Horticulturae

The current mechanical harvesting methods of Lycium barbarum L. are labor intensive and cause too much damage, but vibrating and comb‐brushing harvesting can increase the efficiency while minimizing the damage. However, optimizing the main factors and their parameter values of vibrating and comb‐brushing harvesting is challenging. To achieve the high‐efficiency and low‐damage harvesting of L. barbarum, firstly, the mechanical models of the materials used in the experiments were established based on the physical tests. Then, the vibrating and comb‐brushing harvesting simulations were conducted based on FEM to acquire the ranges of the parameter values. The effects of the rotating speed, material, and amplitude on the harvesting rate of ripe fruit and harvesting rate of unripe fruit, as well as the damage rate of ripe fruit were determined based on RSM. Finally, the optimized parameters were obtained and verified using the field experiments. The field experiments showed that the harvesting rate of ripe fruit was 85.8%, the harvesting rate of unripe fruit was 10.5%, and the damage rate of ripe fruit was 9.7%. The findings provided the optimal parameter values, which were a design basis for the vibrating and comb‐brushing harvesters of L. barbarum.

DOI： 10.3390/horticulturae7090286

Using near-infrared spectroscopy to determine moisture content, gel strength, and viscosity of gelatin 査読有り国際共著

Duthen, S; Levasseur-Garcia, C; Kleiber, D; Violleau, F; Vaca-Garcia, C; Tsuchikawa, S; Raynaud, CD; Daydé, J

FOOD HYDROCOLLOIDS 115 巻頁： 106627 - 106627 2021年6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：Food Hydrocolloids

Gelatin is a natural biopolymer obtained by denaturation and partial hydrolysis of fibrous collagen, which is a fibrous protein present in the connective tissues of all species in the animal kingdom. Gelatin is used in many different industries, such as food, pharmaceuticals, photography, and cosmetics. The control of its physical properties is therefore of primary economic and technical importance for the gelatin industry, in particular because drying gelatin is the most expensive step in the manufacturing process and because customers demand products with well-controlled moisture content, gel strength, and viscosity. Consequently, a tool that provides rapid and nondestructive, real time analysis of gelatin would provide a definite competitive advantage. One such tool may be near-infrared (NIR) spectroscopy, which is a well-known analytical technique to determine the moisture content of complex matrices. We therefore use this technique to determine the moisture content, gel strength, and viscosity of 135 industrial gelatins. NIR spectra were acquired by using in reflectance mode a Fourier-transform NIR spectrometer with an integrating sphere to make a chemometric study of the industrial gelatins to determine the accuracy with which this technique can estimate moisture content, gel strength, and viscosity. The predictive accuracy for these parameters is quantified by using the ratio of performance of deviation (RPD), which gives 8.8, 3.7, and 2.1 in cross-validation, and 3.9, 1.8, and 1.9 in testing, respectively. Finally, we discuss the use of this technique in industrial conditions.

DOI： 10.1016/j.foodhyd.2021.106627

Terahertz time-domain spectroscopy as a novel tool for crystallographic analysis in cellulose: the potentiality of being a new standard for evaluating crystallinity 査読有り

Wang, H; Tsuchikawa, S; Inagaki, T

CELLULOSE 28 巻 ( 9 ) 頁： 5293 - 5304 2021年6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：Cellulose

Given that terahertz (THz) radiation responds to intermolecular forces such as hydrogen bonds, THz time-domain spectroscopy (THz-TDS) has expanded possibilities in cellulose research. In this study, THz-TDS was used to investigate the crystallinity of three types of cellulose-based materials. Microcrystalline cellulose (MCC) and wood were ball milled at different times, and pseudo-wood was a mixture of MCC and lignin of different mass fractions. All the samples showed peaks at 3.04 THz in the THz mass absorption coefficient spectra. Further, the spectra from 2.79 THz to 3.32 THz were cut out and detrended by subtraction from a baseline. The integrated intensity of the detrended spectra showed a correlation with the mass fraction of lignin of the pseudo-wood samples, and ball milling time of the MCC and wood samples. The correlation was similar with the crystallinity index calculated from X-ray powder diffraction. Moreover, the original wood sample without ball milling had an integrated intensity that was about 30% that of the original MCC sample, matching with the cellulose concentration of the wood (about 30% to 40%). We normalized the integrated intensity of 2.79 THz to 3.32 THz into 1 to 0 by a min–max algorithm and proposed a new “index” for evaluating crystallinity.

DOI： 10.1007/s10570-021-03902-x

その他リンク： https://link.springer.com/article/10.1007/s10570-021-03902-x/fulltext.html

Modal Analysis and Experiment of a <i>Lycium barbarum</i> L. Shrub for Efficient Vibration Harvesting of Fruit 査読有り Open Access

Zhao, J; Tsuchikawa, S; Ma, T; Hu, GR; Chen, Y; Wang, ZW; Chen, QY; Gao, ZN; Chen, J

AGRICULTURE-BASEL 11 巻 ( 6 ) 頁： 519 - 519 2021年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Agriculture Switzerland

The most common harvesting method of Lycium barbarum L. (L. barbarum) is manual harvesting, resulting in low efficiency and high cost. Meanwhile, the efficiency of vibration harvesting, which is considered an efficient mechanical harvesting method, can be significantly improved if the optimized resonance frequency of the shrub can be obtained. To vibration harvest fruit efficiently, a 3D model of the shrub was established based on measurements of the shape parameters, and material mechanics models of the branches were established based on physical tests. The modal analysis of the shrub based on finite element method (FEM) simulation was performed to obtain the range of resonance frequency, and the modal experiment of the shrub using acceleration sensors and an impact hammer was conducted to obtain the accurate resonance frequency. Based on the results of the modal analysis and experiment, the optimized resonance frequency was determined to be 2 Hz. The field experiment showed that the fruit fell off when the branches were vibrated at this frequency. The results provide the design basis for the efficient vibration harvesting of L. barbarum.

DOI： 10.3390/agriculture11060519

Finite Element Method Simulations and Experiments of Detachments of <i>Lycium barbarum</i> L. 査読有り Open Access

Zhao, J; Ma, T; Inagaki, T; Chen, QY; Gao, ZN; Sun, LJ; Cai, HX; Chen, C; Li, CL; Zhang, SX; Tsuchikawa, S; Chen, J

FORESTS 12 巻 ( 6 ) 頁： 699 - 699 2021年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Forests

When harvesting Lycium barbarum L., excess amounts of detachments of the half-ripe fruit, unripe fruit, flowers, and leaves significantly affect the yield and adversely affect the subsequent processing, such as drying and grading. Finite element method (FEM) simulations and experiments of detachments were performed to harvest more ripe fruit and less half-ripe fruit, unripe fruit, flowers, and leaves. Three-dimensional (3D) models of the ripe fruit, half-ripe fruit, unripe fruit, flowers, leaves, fruit calyxes (flower calyx), fruit stems (flower stem), and branches were constructed using a 3D scanner, and material mechanics models of the above parts were established based on physical tests with universal testing machines. Detachment simulations and experiments of the ripe fruit, half-ripe fruit, unripe fruit, flowers, and leaves were performed to determine the detachment mechanisms and sequences. The detachment forces of each set of two parts were obtained. The field experiments showed that the detachment force between the fruit and calyx of ripe fruit was the lowest value of these forces, and only the ripe fruit was the first to detach from the calyx when harvesting. The results provided data support on the mechanics properties of wood and the optimization basis for the harvesting method of L. barbarum.

DOI： 10.3390/f12060699

Demonstration of the applicability of visible and near-infrared spatially resolved spectroscopy for rapid and nondestructive wood classification 査読有り Open Access

Ma, T; Inagaki, T; Tsuchikawa, S

HOLZFORSCHUNG 75 巻 ( 5 ) 頁： 419 - 427 2021年5月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Holzforschung

Although visible and near-infrared (Vis-NIR) spectroscopy can rapidly and nondestructively identify wood species, the conventional spectrometer approach relies on the aggregate light absorption due to the chemical composition of wood and light scattering originating from the physical structure of wood. Hence, much of the work in this area is still limited to further spectral pretreatments, such as baseline correction and standard normal variate to reduce the light scattering effects. However, it should be emphasized that the light scattering rather than absorption inwood is dominant, and thismust be effectively utilized to achieve highly accurate and robust wood classification. Here a novelmethod based on spatially resolved diffuse reflectance (wavelength range: 600-1000 nm) was demonstrated to classify 15 kinds of wood. A portable Vis-NIR spectral measurement system was designed according to previous simulations and experimental results. To simplify spectral data analysis (i.e., against overfitting), support vector machine (SVM) model was constructed for wood sample classification using principal component analysis (PCA) scores. The classification accuracies of 98.6% for five-fold crossvalidation and 91.2%for test set validation were achieved. This study offers enhanced classification accuracy and robustness over other conventional nondestructive approaches for such various kinds of wood and sheds light on utilizing visible and short-wave NIR light scattering for wood classification.

DOI： 10.1515/hf-2020-0074

その他リンク： https://www.degruyter.com/document/doi/10.1515/hf-2020-0074/xml

Characteristics of Self-Excited Alternate-Tooth Vibration of Circular Saw Blade 査読有り Open Access

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

BIORESOURCES 16 巻 ( 2 ) 頁： 3840 - 3850 2021年5月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Bioresources

In recent years, circular saw blades with thinner kerfs have been in high demand for improvement of the production yield of wood-based materials and the reduction of sawdust. In the case of ripping of solid wood, the number of teeth of a circular saw blade is normally set to 40 or 50, with a diameter of 305 mm, which allows less cutting resistance and smooth exhausting of sawdust. However, at certain rotational speeds, self-excited alternate-tooth vibration can easily occur in circular saw blades with such thin kerfs and so few teeth. Therefore, the cutting surface quality tends to be worse. In this study, the mechanism of this self-excited alternate-tooth vibration was clarified. The vibration mode and frequency were predicted by the finite element method. In addition, a circular saw blade with a body thickness 1.5 mm and 50 teeth was employed for wood-cutting experiments. The rotational speed range of the self-excited alternate-tooth vibration modes and their frequencies were investigated. When a double of the tooth passage frequency was slightly higher than the frequencies of the alternate-tooth vibration modes, an alternate-tooth vibration of the regenerative chatter type was excited, owing to the forces on the sides of the tooth.

DOI： 10.15376/biores.16.2.3840-3850

Non-destructive and fast method of mapping the distribution of the soluble solids content and pH in kiwifruit using object rotation near-infrared hyperspectral imaging approach 査読有り国際共著

Ma, T; Xia, Y; Inagaki, T; Tsuchikawa, S

POSTHARVEST BIOLOGY AND TECHNOLOGY 174 巻 2021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

This work aimed to offer a non-destructive and fast approach to visualizing the soluble solids content (SSC) and acidity (pH) of the whole kiwifruit. Most of the visible-near-infrared spectral imaging techniques used in postharvest fruit and vegetables assessment exhibit issues related to the identification of the quality spatial distribution within intact samples, mainly due to sampling surface curvature effects. Here, a push-broom-type NIR hyperspectral imaging camera and a sample rotation stage were combined to scan entire kiwifruit surfaces. Then, key wavelengths in the range of 1002–2300 nm were extracted for constructing SSC and pH calibration models by partial least squares regression analysis. The resulting SSC prediction accuracy was sufficiently high: the coefficient of determination (R<sup>2</sup><inf>cv</inf>) and the root mean square error (RMSE<inf>cv</inf>) of cross-validation set were 0.74 and 0.7 %, respectively. For pH, the R<sup>2</sup><inf>cv</inf> and RMSE<inf>cv</inf> were 0.64 and 0.14, respectively. Finally, the SSC and pH 360˚mapping results surpassed earlier works in this area that they showed a distinct spatial distribution within each intact sample. It was concluded that the proposed object rotation hyperspectral imaging approach is promising for the non-destructive prediction mapping of SSC and pH in kiwifruit or other cylindrical-shaped samples.

DOI： 10.1016/j.postharvbio.2020.111440

Rapid and nondestructive evaluation of hygroscopic behavior changes of thermally modified softwood and hardwood samples using near-infrared hyperspectral imaging (NIR-HSI) 査読有り国際共著

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

HOLZFORSCHUNG 75 巻 ( 4 ) 頁： 345 - 357 2021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：Holzforschung

The objective of this work was to provide a rapid and nondestructive imaging method for evaluating the hygroscopic behavior of thermally modified lignocellulosic materials (softwood and hardwood). The difference in the hygroscopic behavior was explained by moisture content (MC) mapping results and molecular association characteristics of absorbed water (i.e. weakly, moderately, and strongly hydrogen-bonded water molecules) with wood at various relative humidities (RH). To achieve this goal, near-infrared (NIR) spectral images in the wavelength range 1816-2130 nm (covering the combination of stretching and deformation vibrations for OH) were used to visualize MC distributions over the surface of Japanese cedar and European beech samples which had been thermally treated at different temperatures. A curve fitting method was utilized to explore changes in water-wood structure characteristics based on shifts to longer wavelength in spectral signals caused by increasing MC. The curve fitting results support the recent nuclear magnetic resonance (NMR) studies that different bound water stabilities may pool in different compartments of the wood cell wall. Furthermore, water was firmly bound to wood at low RHs and H-bonds gained mobility as the number of absorbed molecules increased. It is concluded that NIR hyperspectral imaging also has the potential to be a complementary methodology for studying the transient changes of wood-water interactions before equilibrium.

DOI： 10.1515/hf-2019-0298

Rapid and nondestructive evaluation of soluble solids content (SSC) and firmness in apple using Vis–NIR spatially resolved spectroscopy 査読有り

Ma T., Xia Y., Inagaki T., Tsuchikawa S.

Postharvest Biology and Technology 173 巻 2021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：Postharvest Biology and Technology

Visible–near infrared (Vis–NIR) spectroscopy is a rapid and nondestructive method used to characterize organic compounds in postharvest fruit and vegetable assessment. However, developing robust calibration models is a challenge as conventional spectrometers collect only the cumulative effects of light absorption and scattering. In this study, a multifiber-based Vis–NIR spatially resolved spectra measurement system was designed for simultaneous evaluation of soluble solid content (SSC) and firmness in apple. Thirty silica fibers separated into five groups at 1, 2, 3, 4, and 5 mm away from the light illumination point and connected to a cost-effective Vis–NIR hyperspectral imaging camera were used to acquire spectral data with an improved signal-to-noise ratio (S/N) by a two-step signal averaging process (i.e., 30 camera pixels per fiber and six optical fibers per group). Reflectance ratio spectra were then calculated by dividing the diffusely reflected light intensity detected at distance d +△ by that detected at distance d to realize a light reference-free approach. Finally, the useful explanatory variables were selected by competitive adaptive reweighted sampling (CARS) to construct individual calibration models for various regions. The coefficients of determination (R<inf>cal</inf><sup>2</sup>) and the root mean square errors (RMSE<inf>cal</inf>) of the best-performing calibration models were approximately 0.97 and 0.20 % for SSC and 0.96 and 0.37 N for firmness, respectively. Furthermore, the predicted results were 0.92 and 0.35 % for SSC and 0.87 and 0.71 N for firmness. Our method offers low-cost and portable detection of SSC and firmness for postharvest fruit evaluation.

DOI： 10.1016/j.postharvbio.2020.111417

Rapid and nondestructive evaluation of soluble solids content (SSC) and firmness in apple using Vis-NIR spatially resolved spectroscopy 査読有り

Ma, T; Xia, Y; Inagaki, T; Tsuchikawa, S

POSTHARVEST BIOLOGY AND TECHNOLOGY 173 巻 2021年3月

Photodegradation Properties of Earlywood and Latewood Spruce Timber Surfaces 査読有り国際共著 Open Access

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

Acta Silvatica et Lignaria Hungarica 17 巻 ( 1 ) 頁： 9 - 20 2021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

Spruce (Picea abies Karst.) samples were irradiated using an ultraviolet light emitter mercury vapour lamp. The examined specimen surfaces contained earlywood or latewood to determine the photodegradation properties of these two tissue types. The generated chemical changes were monitored by diffuse reflectance Fourier transformed infrared spectroscopy. The difference spectrum method was used to present absorption changes. The earlywood suffered considerably greater degradation than the latewood during the UV irradiation. Most of the lignin molecules in the examined surface layer degraded during the first 11 days of UV irradiation for both earlywood and latewood. Results demonstrated that two types of unconjugated carbonyls absorbing at 1705 and 1764 cm-1 wavenumbers were created during the photodegradation. Time dependence of the absorption changes showed correlation between the guaiacyl lignin degradation and the generation of unconjugated carbonyl group absorbing at 1764 cm-1 wavenumber.

DOI： 10.37045/aslh-2021-0001

Terahertz time-domain spectroscopy as a novel tool for crystallographic analysis in cellulose 査読有り

Wang, H; Horikawa, Y; Tsuchikawa, S; Inagaki, T

CELLULOSE 27 巻 ( 17 ) 頁： 9767 - 9777 2020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：Cellulose

Terahertz (THz) radiation is responsive to optical phonons in crystal lattices; therefore, THz time-domain spectroscopy (THz-TDS) has potential utility in crystallographic analysis. In this study, THz-TDS was used to investigate cellulose samples extracted from different sources with varying ratios of Iα and Iβ fractions. This is the first study to report that the absorption coefficient in the THz region of cellulose Iα and Iβ presents different characteristic absorption peaks around 2 THz. This can be used to distinguish the cellulose I allomorph, which exhibits differences in its crystalline structure. The absorption coefficient at 2.11 and 2.38 THz showed a considerable linear correlation with the Iα fraction of the cellulose samples. The absorption coefficient spectra of 1.88–3.40 THz were further detrended and separated into three Gaussian peaks. The correlations between the parameters of these separated peaks (integrated intensities, peak positions) and the crystalline structural values (d-spacing, crystalline size, crystallinity index) that calculated from the X-ray diffraction (XRD) pattern were investigated.

DOI： 10.1007/s10570-020-03508-9

Rapid and non-destructive seed viability prediction using near-infrared hyperspectral imaging coupled with a deep learning approach 査読有り

Ma, T; Tsuchikawa, S; Inagaki, T

COMPUTERS AND ELECTRONICS IN AGRICULTURE 177 巻 2020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：Computers and Electronics in Agriculture

Seeds are the basis of the agricultural food industry, greater insights into seed viability before sowing could improve storage management and field performance. In the present study, we aimed to address this issue by using highly cost-efficient near-infrared hyperspectral imaging (NIR-HSI) and a convolutional neural network (CNN) deep learning approach. An NIR-HSI camera was used because it can recognize both molecular vibration information (i.e. chemical component differences) and its spatial distribution in each seed sample; this camera is much more informative than a regular RGB digital camera. Using this technology, the emphasis of this study was firstly to provide a methodology for enhancing the interpretability of viable and non-viable seeds via principal component analysis (PCA) and support vector machine (SVM) viability classification analysis of NIR-HSI data. A CNN was then constructed to“cognize” the differences in viable and non-inviable seeds and classify them automatically. Experimental results indicate that the methodology produces a ~90% classification accuracy for both a five-fold cross-validation set and a test set of naturally aged Japanese mustard spinach seeds. Therefore, this study provides a new strategy for effective and practical seed viability prediction.

DOI： 10.1016/j.compag.2020.105683

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