Wuled Lenggoro | Tokyo University of Agriculture and Technology (original) (raw)
Papers by Wuled Lenggoro
Royal Society Open Science, 2023
The present study used optical coherence tomography (OCT) to monitor the dynamics of a highly vis... more The present study used optical coherence tomography (OCT) to monitor the dynamics of a highly viscous liquid in a porous tobacco substrate during heating. The OCT technique was integrated with a specially designed heating chamber and an air pump for measuring. Two transitional points in the liquid behaviours at different temperatures were estimated using OCT and statistical analysis of the attenuation coefficient. The first point, ‘A’, shows the time approximation at which the penetration-dominant zone transitions into the evaporation-dominant zone. The second point, ‘B’, indicates the time approximation at which rapid evaporation of free liquid transitions into slow evaporation of trapped and bound liquid. This analytical system is an alternative for tracking liquid transport in porous biomass during heating.
Particuology, 2024
Understanding aerosol-vegetation interactions is vital in ecosystems. However, the interactions r... more Understanding aerosol-vegetation interactions is vital in ecosystems. However, the interactions remain elusive partly due to the lack of suitable plant growth chamber systems. Particularly, deposition of submicron particles on leaf surfaces is challenging due to its low deposition velocities compared to larger particles. In this work, we present a plant-growth chamber that was used to study the effect of submicron black carbon (BC) particles on the growth and photosynthesis of plants. The chamber system simultaneously enables the growth of multiple plants in pots and the deposition of submicron particles onto them. Two spraying methods assisted by ultrasonic and electrostatic forces were employed as aerosol generators to realize the particle deposition. The flow regime inside the chamber was numerically calculated to predict the transportation of aerosol particles, suggesting the optimal operating conditions of the chamber. The gas-phase particle size distribution measurements showed that generated BC particles were suspended in submicron diameter ranges. The aerosol generators were examined in the chamber using three conductor and insulator substrates as a model of plant leaves. Microscope observations and spectroscopic analysis ascertained that submicron BC particles generated from our generators were deposited on all substrate surfaces. Using the developed chamber system, systematic studies can be performed to advance the fundamental understanding of aerosol-vegetation interactions.
Plant Physiology and Biochemistry, 2024
The introduction of exogenous particles into plants has promising applications in agriculture and... more The introduction of exogenous particles into plants has promising applications in agriculture and biotechnology. Nanoparticles can be transported into plants through foliar application or root uptake. However, both methods have limitations in terms of the size of the particles (<40 nm) that can be transported due to the barriers of the cell wall and cuticle. In the present study, we proposed a novel method to deliver particles of up to 110 nm into plants by cutting the stem of tomato seedlings. We demonstrated for the first time, using water-insoluble silica colloids, that not only nanoparticles but also submicron particles can be transported toward the leaves when the plant stem is used as the entry point of particles. Thirty-five-day-old tomato seedlings were used as the target plants. When the cut stem seedlings were immersed in the colloidal particle suspension for up to 24 h, significant particle accumulation was observed in the nodes and leaves. The relatively low particle concentrations (10 mg/L) allowed effective transport throughout the plants. Silica particles with average diameters of 10 nm and 110 nm were both well transported and moved through the stem. Even after the particles entered the plant, adventitious roots were formed, resulting in the formation of whole plants with roots, stems, and leaves. This method can be applied not only to tomatoes but also to other food crops for various applications in plant biotechnology.
Advanced Powder Technology, 2023
Solar distillation, a promising technique for water purification and desalination, requires photo... more Solar distillation, a promising technique for water purification and desalination, requires photothermal materials to efficiently convert solar energy into heat. In this study, a novel method is proposed wherein fresh carbonaceous (soot) particles, as a photothermal material, are embedded into electrospun fibrous membranes by burning candles (to produce soot) and electrospinning of polymer material simultaneously. The proposed method can produce several types of membranes with various particle positions (interior or exterior) in the polymer fiber. The particle positions were adjusted by changing the introduction points of particles using a polymer jet. Polymer fibers with diameters of several hundred nanometers were fabricated. Experiments revealed that the soot particle position did not influence the photothermal conversion performance of the membranes. The fabricated membrane could improve the heat localization up to 194.5% and exhibited water distillation and desalination rates as high as 1.60 and 1.55 kg m À2h À1 , respectively, under 1-sun solar light irradiation. The proposed method opens a new route for the functionalization of polymer membranes.
Optical Review, 2023
Dynamics of water content in a biological tissue is an important information of a biological acti... more Dynamics of water content in a biological tissue is an important information of a biological activity. However, although the conventional measurement method measures the total amount of water contained in the tissue, there is no established method for quantitatively measuring the amount of water localized in biological tissue. A spectral-domain optical coherence tomography system (SD-OCT) using two near-infrared wavelengths was developed for applications in cross-sectional imaging and quantitative analysis of evaporation at room temperature. The wavelengths of the light sources were selected as 1060 nm, which is hardly absorbed by water, and 1470 nm, which is absorbed by a factor of 220. In this study, we examined the effect of water absorption and scattering on the attenuation coefficient in a dense medium using a two-wavelengths OCT and showed the possibility of measuring the dynamics of water in the evaporation process through light scattering. Experimental results showed that the attenuation coefficient in a dense medium was more affected by scattering than water absorption. They are highly influenced by scattering caused by the temporal variation of the refractive-index matching effect between the hydrogen-bonded cellulose and free water around it in the process of evaporation. It was concluded that the SD-OCT was a quite practical and useful tool to visualize and quantitatively analyze natural phenomena that have never previously been observed.
Malaysian Journal of Fundamental and Applied Sciences, 2020
The effect of chemical treatment of a metallic substrate on the deposition of aerosols generated ... more The effect of chemical treatment of a metallic substrate on the deposition of aerosols generated by an ultrasonic nebulizer was investigated. A single substrate with areas having different "level" of hydrophilicity (or hydrophobicity) was used as a model surface. The treated (more hydrophilic) area became more negatively-charged based on a surface electric potential meter. A low-pressure analysis method (electron-microscope image) and ordinary pressure methods (Raman spectroscopy and X-ray fluorescence) analytical results indicated that in comparison with the untreated area, the treated area trapped more particles in the case of the deposition of "wet" aerosols. In the case of the deposition of more "dry" aerosols, the untreated area trapped more particles rather than that of the treated one. The efficiency of particles deposition not only depended on the degree of hydrophilicity (or hydrophobicity) of the surface but also due to the conditions (wet or dry) of incoming aerosols.
Journal of Chemical Engineering of Japan, 2021
A protocol for the detachment of solid samples deposited on at substrates and their collection in... more A protocol for the detachment of solid samples deposited on at substrates and their collection in aqueous samples is proposed based on a suspension-assisted ultrasonic method. As samples, combustion-synthesized magnesium oxide aggregates in the submicron size range were deposited in the gas phase onto three kinds of substrates: a silicon wafer and coarse and ne alumina-coated resin sheets. To enhance the sample particle detachment, a solid-liquid suspension made of candle combustion soot particles was selected as an ultrasound propagation medium, which is di erent from the usual liquid medium, such as water, a surfactant solution, or a solvent. Preliminary detachment experiments were performed using low-power (42 kHz and 35 W) ultrasonication, and the substrates and suspensions were analyzed using scanning electron microscopy (SEM) images and particle size distributions based on dynamic light scattering, respectively. The detachment e ciency, de ned as the fraction of cleaned area on a substrate, was determined from the SEM images and indicates that the detachment using the medium with soot had a higher e ciency compared to that without soot, and there was an optimum soot concentration for particle detachment for all three substrates. The suspension particle size distribution after ultrasonication showed good dispersion of the sample particles in the soot suspension.
Advanced Powder Technology, 2022
To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. ... more To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. However, the environmental impact of plastic waste is a concern. Therefore, herein we report that a silane coupling agents-based coating can be applied to natural clayey soil samples to suppress water evaporation. The hydrophobicity of soils (particle sizes 200-500 µm) can be enhanced. Evaporation flux was investigated using an electronic balance placed inside a chamber by maintaining constant flow, temperature, and relative humidity. The magnitude of evaporation flux was adjusted by placing a hydrophobic-treated soil layer in the system. It is clear that the hydrophobictreated soil particle layer interacts with water capillaries to reduce the evaporation flux, but the effect on water vapor diffusion was small.
e-Journal of Surface Science and Nanotechnology, 2022
In this study, we report for the first time the use of colloidal fluorescent submicrometer-sized ... more In this study, we report for the first time the use of colloidal fluorescent submicrometer-sized particles as tracers for microliter liquid transport through multilayered biomass. We showed that the in-plane spread and the trans-planar penetration of the liquid can be visualized by mapping the fluorescent particle distribution in each biomass layer using image analysis. The temperature and inter-layer connectivity were found to be vital factors determining the fate of the liquid transport. Inter-layer connectivity is influenced by both the physical connections among the layers and the property of the fluid filling the inter-layer pores. Utilizing this characteristic, we could use our visualization method to detect trace amounts of nano-to sub-micrometer impurities in one of the layers.
Advanced Powder Technology, 2022
The resistance to deagglomeration of spray-dried agglomerated particles of submicron size was inv... more The resistance to deagglomeration of spray-dried agglomerated particles of submicron size was investigated using an ultrasonication system in water. Submicron agglomerates consisting of water-insoluble primary particles with size of 10 or 100 nm were prepared in different shapes by varying the heating profile during spray drying. Deagglomeration experiments were performed using a low-power sonication device. Spherical agglomerates were found to be more resistant to ultrasonic forces, while dent-or doughnut-shaped agglomerates tended to break down. The results show that the shape of the agglomerate plays an important role in the energy balance of the ultrasound operation. The energy produced from the collapse of cavitation bubbles in the ultrasound vessel may be used to promote motion of the agglomerates and deagglomeration.
Advanced Powder Technology, 2022
To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. ... more To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. However, the environmental impact of plastic waste is a concern. Therefore, herein we report that a silane coupling agents-based coating can be applied to natural clayey soil samples to suppress water evaporation. The hydrophobicity of soils (particle sizes 200-500 mm) can be enhanced. Evaporation flux was investigated using an electronic balance placed inside a chamber by maintaining constant flow, temperature, and relative humidity. The magnitude of evaporation flux was adjusted by placing a hydrophobic-treated soil layer in the system. It is clear that the hydrophobic-treated soil particle layer interacts with water capillaries to reduce the evaporation flux, but the effect on water vapor diffusion was small.
World Academy of Science, Engineering and Technology, International Journal of Chemical, Molecular, Nuclear, Materials and Metallurgical Engineering, 2016
In this study, encapsulation of agarwood oil with non-ionic surfactant, Tween 80 was prepared at ... more In this study, encapsulation of agarwood oil with non-ionic surfactant, Tween 80 was prepared at critical micelle concentration of 0.0167 % v/v to produce the most stable nano-emulsion in aqueous. The encapsulation has minimized the bioactive compounds degradation in various pH conditions thus prolong their shelf life and maintained its initial oil grade. The oil grading of the prepared samples were conducted using the gel electrophoresis instead of using common analytical industrial grading such as gas chromatographymass spectrometry (GCMS). The grading method was chosen due to their unique zeta potential value after the encapsulation process. This paper demonstrates the feasibility of applying the electrophoresis principles to separate the encapsulated agarwood oil or grading of the emulsified agarwood oil. The results indicated that the grading process are potential to be further investigate based on their droplet size and zeta potential value at various pH condition when the dro...
To understand the effect of aerosols on the growth and physiological conditions of trees in fores... more To understand the effect of aerosols on the growth and physiological conditions of trees in forests, it is important to know the state of aerosols that are deposited on the surface of the leaves or needles. In this study, we developed methods of visualization of submicron-sized aerosols that were artificially deposited from the gas-phase or liquid phase onto tree leaves or needles in trees. Firstly, we used field-emission scanning electron microscopy (FE-SEM) to observe black carbon (BC) particles that were artificially sprayed onto the leaves or needles. The distribution of BC particles deposited on the leaves and needles were distinguished based on the size and morphological features of the particles. The distribution and agglomerates size of BC particles differed between two spraying methods of BC particles employed. Secondly, we tried to visualize gold (Au) particles that were artificially sprayed onto the leaves using energy dispersive X-ray spectrometry (EDX) coupled to FE-SEM. We detected the Au particles based on the characteristic X-ray spectrum, which was secondarily generated from the Au particles. In contrast to the case of BC particles, the Au particles did not form agglomerates and were uniformly distributed on the leaf surfaces. The present results show that our methods provide useful information of adsorption and/or behavior of fine particles at the submicron level on the surface of the leaves.
To perform quick measurements of black carbon (BC) particles deposited on foliar surfaces of fore... more To perform quick measurements of black carbon (BC) particles deposited on foliar surfaces of forest tree species, we investigated an optical method for measuring the amount of BC extracted from foliar surfaces and collected on quartz fiber filters. The seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to submicron BC particles for one growing season (1 June to 7 December 2009). At the end of the growing season, the leaves or needles of the seedlings were harvested and washed with deionized water followed by washing with chloroform to extract the BC particles deposited on the foliar surfaces. The extracted BC particles were collected on a quartz fiber filter. The absorption spectrum of the filters was measured by spectrophotometer with an integrating sphere. To obtain the relationship between the absorbance of the filter and the amount of BC particles on the filter, the amount of BC particles on the filter was determined as that of elemental carbon (EC) measured by a thermal optical method. At wavelengths below 450 nm, the absorption spectrum of the filter showed absorption by biological substances, such as epicuticular wax, resulting in the low coefficient of determination (R 2 ) in the relationship between the amount of EC on the filter (M EC , μg C cm -2 filter area) and the absorbance of the filter. The intercept of the regression line between M EC and the absorbance of the filter at 580 nm (A 580 ) was closest to 0. There was a significant linear relationship between the A 580 and M EC (R 2 = =0.917, p⁄0.001), suggesting that the amount of BC particles collected on the filter can be predicted from the absorbance. This optical method might serve as a simple, fast and cost-effective technique for measuring the amount of BC on foliar surfaces.
To clarify the effects of black carbon (BC) particles on growth and gas exchange rates of Asian f... more To clarify the effects of black carbon (BC) particles on growth and gas exchange rates of Asian forest tree species, the seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to BC particles with sub-micron size for two growing seasons from 1 June 2009 to 11 November 2010. The BC particles deposited after the exposure to BC were observed on the foliar surface of the 4 tree species. At the end of the experiment, the amount of BC accumulated on the foliar surface after the exposure to BC aerosols were 0.13, 0.69, 0.32 and 0.58 mg C m -2 total leaf area in F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings, respectively. In August 2010, the exposure to BC particles did not significantly affect net photosynthetic rate under any light intensity, stomatal diffusive conductance to water vapour (g s ), stomatal limitation of photosynthesis, response of g s to increase in vapour pressure deficit and leaf temperature under light saturated condition in the leaves or needles of the seedlings. These results suggest that the BC particles deposited on the foliar surface did not reduce net photosynthesis by shading, did not increase leaf temperature by absorption of irradiation light, and did not induce plugging of stomata in the leaves or needles of the seedlings. There were no significant effects of BC particles on the increments of plant height and stem base diameter during the experimental period and the whole-plant dry mass at the end of the experiment. These results indicate that the exposure to BC particles with sub-micron size for two growing seasons did not significantly affect the growth and leaf or needle gas exchange rates of F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings.
Royal Society Open Science, 2023
The present study used optical coherence tomography (OCT) to monitor the dynamics of a highly vis... more The present study used optical coherence tomography (OCT) to monitor the dynamics of a highly viscous liquid in a porous tobacco substrate during heating. The OCT technique was integrated with a specially designed heating chamber and an air pump for measuring. Two transitional points in the liquid behaviours at different temperatures were estimated using OCT and statistical analysis of the attenuation coefficient. The first point, ‘A’, shows the time approximation at which the penetration-dominant zone transitions into the evaporation-dominant zone. The second point, ‘B’, indicates the time approximation at which rapid evaporation of free liquid transitions into slow evaporation of trapped and bound liquid. This analytical system is an alternative for tracking liquid transport in porous biomass during heating.
Particuology, 2024
Understanding aerosol-vegetation interactions is vital in ecosystems. However, the interactions r... more Understanding aerosol-vegetation interactions is vital in ecosystems. However, the interactions remain elusive partly due to the lack of suitable plant growth chamber systems. Particularly, deposition of submicron particles on leaf surfaces is challenging due to its low deposition velocities compared to larger particles. In this work, we present a plant-growth chamber that was used to study the effect of submicron black carbon (BC) particles on the growth and photosynthesis of plants. The chamber system simultaneously enables the growth of multiple plants in pots and the deposition of submicron particles onto them. Two spraying methods assisted by ultrasonic and electrostatic forces were employed as aerosol generators to realize the particle deposition. The flow regime inside the chamber was numerically calculated to predict the transportation of aerosol particles, suggesting the optimal operating conditions of the chamber. The gas-phase particle size distribution measurements showed that generated BC particles were suspended in submicron diameter ranges. The aerosol generators were examined in the chamber using three conductor and insulator substrates as a model of plant leaves. Microscope observations and spectroscopic analysis ascertained that submicron BC particles generated from our generators were deposited on all substrate surfaces. Using the developed chamber system, systematic studies can be performed to advance the fundamental understanding of aerosol-vegetation interactions.
Plant Physiology and Biochemistry, 2024
The introduction of exogenous particles into plants has promising applications in agriculture and... more The introduction of exogenous particles into plants has promising applications in agriculture and biotechnology. Nanoparticles can be transported into plants through foliar application or root uptake. However, both methods have limitations in terms of the size of the particles (<40 nm) that can be transported due to the barriers of the cell wall and cuticle. In the present study, we proposed a novel method to deliver particles of up to 110 nm into plants by cutting the stem of tomato seedlings. We demonstrated for the first time, using water-insoluble silica colloids, that not only nanoparticles but also submicron particles can be transported toward the leaves when the plant stem is used as the entry point of particles. Thirty-five-day-old tomato seedlings were used as the target plants. When the cut stem seedlings were immersed in the colloidal particle suspension for up to 24 h, significant particle accumulation was observed in the nodes and leaves. The relatively low particle concentrations (10 mg/L) allowed effective transport throughout the plants. Silica particles with average diameters of 10 nm and 110 nm were both well transported and moved through the stem. Even after the particles entered the plant, adventitious roots were formed, resulting in the formation of whole plants with roots, stems, and leaves. This method can be applied not only to tomatoes but also to other food crops for various applications in plant biotechnology.
Advanced Powder Technology, 2023
Solar distillation, a promising technique for water purification and desalination, requires photo... more Solar distillation, a promising technique for water purification and desalination, requires photothermal materials to efficiently convert solar energy into heat. In this study, a novel method is proposed wherein fresh carbonaceous (soot) particles, as a photothermal material, are embedded into electrospun fibrous membranes by burning candles (to produce soot) and electrospinning of polymer material simultaneously. The proposed method can produce several types of membranes with various particle positions (interior or exterior) in the polymer fiber. The particle positions were adjusted by changing the introduction points of particles using a polymer jet. Polymer fibers with diameters of several hundred nanometers were fabricated. Experiments revealed that the soot particle position did not influence the photothermal conversion performance of the membranes. The fabricated membrane could improve the heat localization up to 194.5% and exhibited water distillation and desalination rates as high as 1.60 and 1.55 kg m À2h À1 , respectively, under 1-sun solar light irradiation. The proposed method opens a new route for the functionalization of polymer membranes.
Optical Review, 2023
Dynamics of water content in a biological tissue is an important information of a biological acti... more Dynamics of water content in a biological tissue is an important information of a biological activity. However, although the conventional measurement method measures the total amount of water contained in the tissue, there is no established method for quantitatively measuring the amount of water localized in biological tissue. A spectral-domain optical coherence tomography system (SD-OCT) using two near-infrared wavelengths was developed for applications in cross-sectional imaging and quantitative analysis of evaporation at room temperature. The wavelengths of the light sources were selected as 1060 nm, which is hardly absorbed by water, and 1470 nm, which is absorbed by a factor of 220. In this study, we examined the effect of water absorption and scattering on the attenuation coefficient in a dense medium using a two-wavelengths OCT and showed the possibility of measuring the dynamics of water in the evaporation process through light scattering. Experimental results showed that the attenuation coefficient in a dense medium was more affected by scattering than water absorption. They are highly influenced by scattering caused by the temporal variation of the refractive-index matching effect between the hydrogen-bonded cellulose and free water around it in the process of evaporation. It was concluded that the SD-OCT was a quite practical and useful tool to visualize and quantitatively analyze natural phenomena that have never previously been observed.
Malaysian Journal of Fundamental and Applied Sciences, 2020
The effect of chemical treatment of a metallic substrate on the deposition of aerosols generated ... more The effect of chemical treatment of a metallic substrate on the deposition of aerosols generated by an ultrasonic nebulizer was investigated. A single substrate with areas having different "level" of hydrophilicity (or hydrophobicity) was used as a model surface. The treated (more hydrophilic) area became more negatively-charged based on a surface electric potential meter. A low-pressure analysis method (electron-microscope image) and ordinary pressure methods (Raman spectroscopy and X-ray fluorescence) analytical results indicated that in comparison with the untreated area, the treated area trapped more particles in the case of the deposition of "wet" aerosols. In the case of the deposition of more "dry" aerosols, the untreated area trapped more particles rather than that of the treated one. The efficiency of particles deposition not only depended on the degree of hydrophilicity (or hydrophobicity) of the surface but also due to the conditions (wet or dry) of incoming aerosols.
Journal of Chemical Engineering of Japan, 2021
A protocol for the detachment of solid samples deposited on at substrates and their collection in... more A protocol for the detachment of solid samples deposited on at substrates and their collection in aqueous samples is proposed based on a suspension-assisted ultrasonic method. As samples, combustion-synthesized magnesium oxide aggregates in the submicron size range were deposited in the gas phase onto three kinds of substrates: a silicon wafer and coarse and ne alumina-coated resin sheets. To enhance the sample particle detachment, a solid-liquid suspension made of candle combustion soot particles was selected as an ultrasound propagation medium, which is di erent from the usual liquid medium, such as water, a surfactant solution, or a solvent. Preliminary detachment experiments were performed using low-power (42 kHz and 35 W) ultrasonication, and the substrates and suspensions were analyzed using scanning electron microscopy (SEM) images and particle size distributions based on dynamic light scattering, respectively. The detachment e ciency, de ned as the fraction of cleaned area on a substrate, was determined from the SEM images and indicates that the detachment using the medium with soot had a higher e ciency compared to that without soot, and there was an optimum soot concentration for particle detachment for all three substrates. The suspension particle size distribution after ultrasonication showed good dispersion of the sample particles in the soot suspension.
Advanced Powder Technology, 2022
To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. ... more To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. However, the environmental impact of plastic waste is a concern. Therefore, herein we report that a silane coupling agents-based coating can be applied to natural clayey soil samples to suppress water evaporation. The hydrophobicity of soils (particle sizes 200-500 µm) can be enhanced. Evaporation flux was investigated using an electronic balance placed inside a chamber by maintaining constant flow, temperature, and relative humidity. The magnitude of evaporation flux was adjusted by placing a hydrophobic-treated soil layer in the system. It is clear that the hydrophobictreated soil particle layer interacts with water capillaries to reduce the evaporation flux, but the effect on water vapor diffusion was small.
e-Journal of Surface Science and Nanotechnology, 2022
In this study, we report for the first time the use of colloidal fluorescent submicrometer-sized ... more In this study, we report for the first time the use of colloidal fluorescent submicrometer-sized particles as tracers for microliter liquid transport through multilayered biomass. We showed that the in-plane spread and the trans-planar penetration of the liquid can be visualized by mapping the fluorescent particle distribution in each biomass layer using image analysis. The temperature and inter-layer connectivity were found to be vital factors determining the fate of the liquid transport. Inter-layer connectivity is influenced by both the physical connections among the layers and the property of the fluid filling the inter-layer pores. Utilizing this characteristic, we could use our visualization method to detect trace amounts of nano-to sub-micrometer impurities in one of the layers.
Advanced Powder Technology, 2022
The resistance to deagglomeration of spray-dried agglomerated particles of submicron size was inv... more The resistance to deagglomeration of spray-dried agglomerated particles of submicron size was investigated using an ultrasonication system in water. Submicron agglomerates consisting of water-insoluble primary particles with size of 10 or 100 nm were prepared in different shapes by varying the heating profile during spray drying. Deagglomeration experiments were performed using a low-power sonication device. Spherical agglomerates were found to be more resistant to ultrasonic forces, while dent-or doughnut-shaped agglomerates tended to break down. The results show that the shape of the agglomerate plays an important role in the energy balance of the ultrasound operation. The energy produced from the collapse of cavitation bubbles in the ultrasound vessel may be used to promote motion of the agglomerates and deagglomeration.
Advanced Powder Technology, 2022
To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. ... more To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. However, the environmental impact of plastic waste is a concern. Therefore, herein we report that a silane coupling agents-based coating can be applied to natural clayey soil samples to suppress water evaporation. The hydrophobicity of soils (particle sizes 200-500 mm) can be enhanced. Evaporation flux was investigated using an electronic balance placed inside a chamber by maintaining constant flow, temperature, and relative humidity. The magnitude of evaporation flux was adjusted by placing a hydrophobic-treated soil layer in the system. It is clear that the hydrophobic-treated soil particle layer interacts with water capillaries to reduce the evaporation flux, but the effect on water vapor diffusion was small.
World Academy of Science, Engineering and Technology, International Journal of Chemical, Molecular, Nuclear, Materials and Metallurgical Engineering, 2016
In this study, encapsulation of agarwood oil with non-ionic surfactant, Tween 80 was prepared at ... more In this study, encapsulation of agarwood oil with non-ionic surfactant, Tween 80 was prepared at critical micelle concentration of 0.0167 % v/v to produce the most stable nano-emulsion in aqueous. The encapsulation has minimized the bioactive compounds degradation in various pH conditions thus prolong their shelf life and maintained its initial oil grade. The oil grading of the prepared samples were conducted using the gel electrophoresis instead of using common analytical industrial grading such as gas chromatographymass spectrometry (GCMS). The grading method was chosen due to their unique zeta potential value after the encapsulation process. This paper demonstrates the feasibility of applying the electrophoresis principles to separate the encapsulated agarwood oil or grading of the emulsified agarwood oil. The results indicated that the grading process are potential to be further investigate based on their droplet size and zeta potential value at various pH condition when the dro...
To understand the effect of aerosols on the growth and physiological conditions of trees in fores... more To understand the effect of aerosols on the growth and physiological conditions of trees in forests, it is important to know the state of aerosols that are deposited on the surface of the leaves or needles. In this study, we developed methods of visualization of submicron-sized aerosols that were artificially deposited from the gas-phase or liquid phase onto tree leaves or needles in trees. Firstly, we used field-emission scanning electron microscopy (FE-SEM) to observe black carbon (BC) particles that were artificially sprayed onto the leaves or needles. The distribution of BC particles deposited on the leaves and needles were distinguished based on the size and morphological features of the particles. The distribution and agglomerates size of BC particles differed between two spraying methods of BC particles employed. Secondly, we tried to visualize gold (Au) particles that were artificially sprayed onto the leaves using energy dispersive X-ray spectrometry (EDX) coupled to FE-SEM. We detected the Au particles based on the characteristic X-ray spectrum, which was secondarily generated from the Au particles. In contrast to the case of BC particles, the Au particles did not form agglomerates and were uniformly distributed on the leaf surfaces. The present results show that our methods provide useful information of adsorption and/or behavior of fine particles at the submicron level on the surface of the leaves.
To perform quick measurements of black carbon (BC) particles deposited on foliar surfaces of fore... more To perform quick measurements of black carbon (BC) particles deposited on foliar surfaces of forest tree species, we investigated an optical method for measuring the amount of BC extracted from foliar surfaces and collected on quartz fiber filters. The seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to submicron BC particles for one growing season (1 June to 7 December 2009). At the end of the growing season, the leaves or needles of the seedlings were harvested and washed with deionized water followed by washing with chloroform to extract the BC particles deposited on the foliar surfaces. The extracted BC particles were collected on a quartz fiber filter. The absorption spectrum of the filters was measured by spectrophotometer with an integrating sphere. To obtain the relationship between the absorbance of the filter and the amount of BC particles on the filter, the amount of BC particles on the filter was determined as that of elemental carbon (EC) measured by a thermal optical method. At wavelengths below 450 nm, the absorption spectrum of the filter showed absorption by biological substances, such as epicuticular wax, resulting in the low coefficient of determination (R 2 ) in the relationship between the amount of EC on the filter (M EC , μg C cm -2 filter area) and the absorbance of the filter. The intercept of the regression line between M EC and the absorbance of the filter at 580 nm (A 580 ) was closest to 0. There was a significant linear relationship between the A 580 and M EC (R 2 = =0.917, p⁄0.001), suggesting that the amount of BC particles collected on the filter can be predicted from the absorbance. This optical method might serve as a simple, fast and cost-effective technique for measuring the amount of BC on foliar surfaces.
To clarify the effects of black carbon (BC) particles on growth and gas exchange rates of Asian f... more To clarify the effects of black carbon (BC) particles on growth and gas exchange rates of Asian forest tree species, the seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to BC particles with sub-micron size for two growing seasons from 1 June 2009 to 11 November 2010. The BC particles deposited after the exposure to BC were observed on the foliar surface of the 4 tree species. At the end of the experiment, the amount of BC accumulated on the foliar surface after the exposure to BC aerosols were 0.13, 0.69, 0.32 and 0.58 mg C m -2 total leaf area in F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings, respectively. In August 2010, the exposure to BC particles did not significantly affect net photosynthetic rate under any light intensity, stomatal diffusive conductance to water vapour (g s ), stomatal limitation of photosynthesis, response of g s to increase in vapour pressure deficit and leaf temperature under light saturated condition in the leaves or needles of the seedlings. These results suggest that the BC particles deposited on the foliar surface did not reduce net photosynthesis by shading, did not increase leaf temperature by absorption of irradiation light, and did not induce plugging of stomata in the leaves or needles of the seedlings. There were no significant effects of BC particles on the increments of plant height and stem base diameter during the experimental period and the whole-plant dry mass at the end of the experiment. These results indicate that the exposure to BC particles with sub-micron size for two growing seasons did not significantly affect the growth and leaf or needle gas exchange rates of F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings.
Seidenki Gakkaishi (Proceedings of the Institute of …, Jan 1, 1997
RSC Advances, 2015
A surface coated with organic molecules has been probed by a sub 100 nm resolution particulate se... more A surface coated with organic molecules has been probed by a sub 100 nm resolution particulate sensor by surface-enhanced Raman scattering (SERS) technique. The spatial distribution of those molecules formed on the solid surface was altered by a dip-coating method as a function of a substrate-lifting rate. Isolated silver nanoparticles ($50 nm) as "antenna" particles were deposited from the gas phase onto the surface by means of an electrostatic-assisted spray. The surface with the particles was analyzed with Raman spectroscopy technique. These analyses provide spatial information on the molecules over the surface, when SERS spectra of the molecules obtained from each measurement point are converted into the position of molecules. The occurrence frequency of SERS is found to be correlated with the two-third power law of the lifting rate which is proportional to a mass concentration of molecules per unit area, whereas the average Raman intensity is independent. A gas-phase route assisted SERS technique offers direct measurement of the molecular patterns on target surfaces.
Journal of the Ceramic Society of Japan, 2014
Lithium manganese oxide (LiMn 2 O 4 ) powders with particle sizes in the range of 100600 nm have ... more Lithium manganese oxide (LiMn 2 O 4 ) powders with particle sizes in the range of 100600 nm have been synthesized through glucose-assisted combustion synthesis. The presence of glucose increases the stability of the precursor solution, purity of the heattreated powders, and decreasing on size of the synthesized particle. The formation of complex metal salts-glucose in the precursor solution and effect of the methods for preparing solid precursors on the final product were investigated.
Journal of Materials Chemistry, Jan 1, 2001
Well-crystallized nanosized CeO 2 single crystals (20-120 nm) were prepared by modifying the aero... more Well-crystallized nanosized CeO 2 single crystals (20-120 nm) were prepared by modifying the aerosol decomposition technique by adding salts to a precursor solution, while the conventional method is only capable of producing submicron to micron sized polycrystalline particles.
Journal of Materials Research, 2005
The one-step synthesis of barium titanate (BaTiO 3 ) nanoparticles was studied by employing a low... more The one-step synthesis of barium titanate (BaTiO 3 ) nanoparticles was studied by employing a low-pressure spray pyrolysis (LPSP) method. The effects of temperature, pressure, and the addition of urea to the precursor were investigated experimentally. The results were compared with the experimental data of the conventional (atmospheric) spray pyrolysis method. It was shown that the BaTiO 3 nanoparticles could be synthesized by the low-pressure method, while only spherical hollow particles with smooth surfaces could be produced by the conventional spray method. The addition of urea greatly improved the crystal growth and particle breakup due to extra heat supplied during the combustion reaction coupled with the evolution of gases. The dispersity of nanoparticles increased with the quantity of urea and with a decrease in pressure. The possible mechanism of the formation of BaTiO 3 nanoparticles in the LPSP process was also proposed.
日本セラミックス協会学術論文誌 Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi, 2005
This study focused on the measurement of the actual charging state of ambient aerosol particles, ... more This study focused on the measurement of the actual charging state of ambient aerosol particles, which is important for understanding the intricate process of adverse health effects caused by particulate matter (PM). The net electrostatic charging state of PM2.5 collected on filter media was measured. The Faraday cage method and surface potential
measurements were used in this study. The results showed that the polarities of the net charging state measured using these two methods were in agreement for 42 out of 48 samples (87.5%), and 36 samples (75%) were negatively charged. The filters were not significantly charged by friction between the filters and air not containing PM. Charge
addition to or leakage from the filters was not observed
over a two-month storage period. Net charging
state of PM2.5 collected on the filters was concluded
to be negative in most cases, based on data’s support of the assumption that aerosol charging state is not altered by the process of PM collection using filter.
Langmuir, 2005
The potential of the electrospray technique in analyzing the structure of nonspherical colloidal ... more The potential of the electrospray technique in analyzing the structure of nonspherical colloidal particles that are below 100 nm in volume-equivalent diameter was demonstrated by online size measurement using a differential mobility analyzer (DMA) with a condensation nucleus counter (CNC) system. The measured mobility of gold nanorods was confirmed by electron microscope images and the theoretical calculation of particle mobility using the dynamic shape factor and slip correction factor. To evaluate the mobility, rod particles were modeled as both a cylinder and a prolate spheroid. This study also showed that the organic surfactant coated on rod particles might be removed and that the rod particles became spherical upon the elevation of the ambient temperature during the gas-phase dispersion of colloidal nanoparticles. Moreover, the thickness of the surfactants coated on rod particles was estimated by comparing the theoretically and experimentally obtained mobilities.
ABSTRACT For standardisation of sampling and measuring methods regarding in-stack measurement of ... more ABSTRACT For standardisation of sampling and measuring methods regarding in-stack measurement of PM2.5 and PM10 mass concentration in flue gas of stationary emission sources, a two stage VIS impactor (virtual impaction surface impactor) was developed in which the solid impaction surface of a conventional impactor is replaced by a space of a relatively slow moving air within a cavity of a receiving nozzle. Separation performance of the VIS impactor was examined using a model aerosol-gas stream system with a variety of dust concentrations and then exploited for the flue gas measurement in a coal combustion plant in China. Because a further stack emission is the condensable suspended particle matter (condensable SPM), two types of diluters for this measurement were designed and constructed based on England et al. and W. Lee et al.’s apparatus. Model exhaust gas with heavy metals was prepared in a laboratory scaled experimental arrangement and was mixed with clean air in both dilutor types. The effects of diluter structure, dilution ratio and residence time on the size distribution of condensable SPM are discussed. Keywords: virtual impaction surface impactor, separation efficiency, dilutor, condensable suspended particulate matter.
Journal of the Society of Powder Technology, Japan, 2014
This research developed international standard methods using virtual impactors and diluters for t... more This research developed international standard methods using virtual impactors and diluters for the in-stack measurement of (i) PM 2.5 and PM 10 mass concentrations and (ii) condensable particles within the flue gases of stationary emission sources (such as factories and power plants). Based on this research, which reflects the importance of the standardization of sampling and measurement methods, international standards for both methods (ISO 13271 and ISO 25597) were published. For the purposes of the ISO publication, the performance of virtual impactors was compared with that of a commercial, conventional two-stage cascade impactor (Real impactor) that collects particles on its solid impaction surfaces. Virtual impactor measurements delivered consistent data in model aerosol testing systems, and in combustion flue gases at testing and commercial plants for coal and other fuels in Japan, Malaysia, and China. The emission behaviors of PM 2.5 and condensable nanoparticles with organic and inorganic trace elements were characterized at each plant by using total surface area-based concentration, size distribution, and a variety of other measurement methods.
Particuology, 2024
Understanding aerosol-vegetation interactions is vital in ecosystems. However, the interactions r... more Understanding aerosol-vegetation interactions is vital in ecosystems. However, the interactions remain elusive partly due to the lack of suitable plant growth chamber systems. Particularly, deposition of submicron particles on leaf surfaces is challenging due to its low deposition velocities compared to larger particles. In this work, we present a plant-growth chamber that was used to study the effect of submicron black carbon (BC) particles on the growth and photosynthesis of plants. The chamber system simultaneously enables the growth of multiple plants in pots and the deposition of submicron particles onto them. Two spraying methods assisted by ultrasonic and electrostatic forces were employed as aerosol generators to realize the particle deposition. The flow regime inside the chamber was numerically calculated to predict the transportation of aerosol particles, suggesting the optimal operating conditions of the chamber. The gas-phase particle size distribution measurements showed that generated BC particles were suspended in submicron diameter ranges. The aerosol generators were examined in the chamber using three conductor and insulator substrates as a model of plant leaves. Microscope observations and spectroscopic analysis ascertained that submicron BC particles generated from our generators were deposited on all substrate surfaces. Using the developed chamber system, systematic studies can be performed to advance the fundamental understanding of aerosol-vegetation interactions.
Particuology, 2024
Understanding aerosol-vegetation interactions is vital in ecosystems. However, the interactions r... more Understanding aerosol-vegetation interactions is vital in ecosystems. However, the interactions remain elusive partly due to the lack of suitable plant growth chamber systems. Particularly, deposition of submicron particles on leaf surfaces is challenging due to its low deposition velocities compared to larger particles. In this work, we present a plant-growth chamber that was used to study the effect of submicron black carbon (BC) particles on the growth and photosynthesis of plants. The chamber system simultaneously enables the growth of multiple plants in pots and the deposition of submicron particles onto them. Two spraying methods assisted by ultrasonic and electrostatic forces were employed as aerosol generators to realize the particle deposition. The flow regime inside the chamber was numerically calculated to predict the transportation of aerosol particles, suggesting the optimal operating conditions of the chamber. The gas-phase particle size distribution measurements showed that generated BC particles were suspended in submicron diameter ranges. The aerosol generators were examined in the chamber using three conductor and insulator substrates as a model of plant leaves. Microscope observations and spectroscopic analysis ascertained that submicron BC particles generated from our generators were deposited on all substrate surfaces. Using the developed chamber system, systematic studies can be performed to advance the fundamental understanding of aerosol-vegetation interactions.
e-Journal of Surface Science and Nanotechnology, 2014
We demonstrate one-step deposition of submicrometer-sized particles suspended in the gas-phase on... more We demonstrate one-step deposition of submicrometer-sized particles suspended in the gas-phase onto a plate type substrate using an electrostatic-assisted spray system. The spray nozzle was set perpendicularly to the substrates (facing the front surface). The particles were deposited on plate-type metallic surfaces, on both front and rear sides of the substrate. This "both-side" deposition can be ascribed to deflection of charged particles in the front side, and then drifting of the particles around the rear side. A numerical simulation also showed that the deposition mechanism was found to be dependent on the center and the edge of the substrate. The electrostatic effect is more effective on both the center and the edge than the diffusion effect.
Journal of Aerosol Science, 2014
The effect of chemical treatment of a metallic substrate on the deposition behavior of charged ae... more The effect of chemical treatment of a metallic substrate on the deposition behavior of charged aerosol particles derived from spraying droplets was investigated. A single substrate with areas having different hydrophilic levels was prepared as target surface. The treated (i.e., higher hydrophilic level) area, measured using a surface potential meter, showed a higher negative potential. A numerical simulation predicted that positively charged aerosol particles tended to approach and were subsequently immobilized on the high hydrophilic area. The area with higher hydrophilicity could collect particles with higher number concentration (density) than the other areas. The relationships were demonstrated in (i) the electrostatic surface potential, (ii) the hydrophilicity of surface, and (iii) the enhancement of adhesive force between the deposited particles and the surface.
Advanced Powder …, Jan 1, 2012
Bulletin of Chemical Reaction Engineering & Catalysis, 2014
The preparation of monodisperse, millimeter-or submillimeter-sized polymeric hydrogel beads by a ... more The preparation of monodisperse, millimeter-or submillimeter-sized polymeric hydrogel beads by a novel production method combining sedimentation polymerization and electrostatic atomization is presented herein. The beads were prepared by drop-wise addition or spray of a pre-gel aqueous solution into silicone oil through a nozzle with application of high voltage, and subsequent free-radical polymerization of the pre-gel droplets during their descent. The thermosensitive poly(N-isopropylacrylamide) hydrogel that was used as the model hydrogel has attracted much attention for application in reaction and separation processes. The size of the pre-gel droplets dispensed from the tip of the nozzle corresponded to the size of the resultant hydrogel beads and was controlled by adjusting the applied voltage. The diameter of the pre-gel droplet was estimated from the equilibrium of forces caused by gravity, the electrostatic force, and the liquid–gas surface tension.
Colloids and Surfaces A: …, Jan 1, 2010
Nanoparticle layers were deposited on a substrate of submillimeter-sized stainless steel wire. Th... more Nanoparticle layers were deposited on a substrate of submillimeter-sized stainless steel wire. The layers were produced from an aqueous TiO2 suspension by pulse direct current (DC) electrophoretic deposition. The electro-sterically stabilized suspension was prepared by beads-milling process with TiO2 powders and an anionic surfactant as starting materials. The solid concentration of the prepared suspensions was 7.5 and 30 wt% concentration with average particle sizes of 10 and 50 nm, respectively. To examine the deposited layer structure, a cross-section was spontaneously cleaved perpendicular to the substrate starting from the inner layer towards the outer layer by applying a heat treatment technique. The state of particle inside the layer deposited by pulse DC charging was compared with the one prepared by conventional DC charging from the aspects of morphology and size distributions. More uniform particle layers can be obtained using the pulse DC charging compared to those of the conventional DC. By using pulse DC, a relatively high volume density of the deposited structure (up to 0.35 kg/m3 at 1.3 V/cm) can be obtained.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014
Potable water from several residential areas on the east coast of Malaysia was filtered using a p... more Potable water from several residential areas on the east coast of Malaysia was filtered using a polyether-sulphone (PES) membrane to separate the coarse and fine iron-oxide particles inside the pipelines. The as-received samples consisted of a wide distribution of particle sizes, ranging from 5 m to 400 nm. The concentration of fine iron-oxide particles inside a distribution system was extremely low. Hence, a specific method is necessary to concentrate and separate the fine particles from the coarse ones. To study the fine particles from the bulk, excess pressure was applied to the membrane filter so that the clogged particles were released into the permeate. A 100 kDa PES membrane was used to separate the particles , because the samples consisted of a wide molecular-weight cutoff range from 89 g/mol goethite (-FeOOH) to 231 g/mol hematite (Fe 2 O 3). After the filtration process, the size distribution of permeated particles reduced to 550–400 nm. Through X-ray diffraction analysis, numerous polymorphs such as-FeOOH, Fe 3 O 4 , Fe 2 O 3 and maghemite were detected from the samples. The zeta potential value of the permeated particles changed from −18.5 to −13 mV, suggesting that the dispersity of permeated iron-oxide particles became unstable, but remained adequate for electrophoretic deposition (EPD). The fibrous carbon electrode used in the EPD process, could remove up to 87% of the permeated iron-oxide particles compared to solid carbon electrodes (<56%). A high-surface-area, porous electrode and a moderate applied voltage were preferred in order to minimise gas formation, reduce the electro-osmosis effect and increase the deposition efficiency.
A nanostructure derived from TiO 2 particle deposition onto a biocomposite surface derived from c... more A nanostructure derived from TiO 2 particle deposition onto a biocomposite surface derived from coir dust (CD) was developed to control degradation using a spray dry technique. To stabilise and reduce the size of dispersed particles, the TiO 2 powder was prepared in deionised water at pH 10 and sonicated at 20 kHz and 400 W. The coir dust was obtained from coconut kernel waste and underwent drying treatment before it was mixed with polypropylene (PP) as the substrate. The suspension consisted of particles with an average size and zeta value of 285 nm and À19.2 mV, respectively. The suspension was spray dried onto a hot-pressed substrate (biocomposite) with a surface roughness between 0.23 and 1.57 lm at ambient temperature. Scanning electron microscopy image analysis and Fourier transform infrared spec-troscopy analysis indicated that the TiO 2 particles were successfully deposited onto the substrate, shown by the existence of a carboxylic acid group (ACOOH) in the CD matrix. Moreover, the weight of the deposited substrate increased exponentially with deposition time compared to pure PP substrate. However, the deposition rate of TiO 2 nanoparticles was limited by the ratio of the substrate surface roughness to particle diameter, as predicted by a previous study.
Atmospheric Environment, 2014
Highlights • Four Japanese forest tree species were exposed to submicrometer (NH4)2SO4 particle... more Highlights
• Four Japanese forest tree species were exposed to submicrometer (NH4)2SO4 particles.
• No significant effect of the particles on growth was observed after 2 years exposure.
• Net photosynthetic rates of 3 species were not significantly changed by the exposure.
• Net photosynthesis of Cryptomeria japonica was relatively sensitive to (NH4)2SO4.
• Both increase and reduction in net photosynthetic rate were observed in C. japonica.
Enzyme and Microbial Technology, 2014
In this study, the potential of electrohydrodynamic atomization or electrospraying to produce nan... more In this study, the potential of electrohydrodynamic atomization or electrospraying to produce nanometerorder CGTase particles from aqueous suspension was demonstrated. CGTase enzyme was prepared in acetate buffer solution (1% v/v), followed by electrospraying in stable Taylor cone-jet mode. The deposits were collected on aluminium foil (collector) at variable distances from the tip of spraying needle, ranging from 10 to 25 cm. The Coulomb fission that occurs during electrospraying process successfully transformed the enzyme to the solid state without any functional group deterioration. The functional group verification was conducted by FTIR analysis. Comparison between the deposit and the as-received enzyme in dry state indicates almost identical spectra. By increasing the distance of the collector from the needle tip, the average particle size of the solidified enzyme was reduced from 200 ± 117 nm to 75 ± 34 nm. The average particle sizes produced from the droplet fission were in agreement with the scaling law models. Enzyme activity analysis showed that the enzyme retained its initial activity after the electrospraying process. The enzyme particles collected at the longest distance (25 cm) demonstrated the highest enzyme activity, which indicates that the activity was controlled by the enzyme particle size.