Optimizing bioconversion processes of rice husk into value-added products: D-psicose, bioethanol, and lactic acid.

Rice husk, rich carbon content, is an agricultural waste produced globally at an amount of 120 million tons annually, and it has high potential as a biorefinery feedstock. Herein, we investigated the feasibility of producing various products as D-psicose, bioethanol and lactic acid from rice husk (RH) through a biorefinery process. Alkali-hydrogen peroxide-acetic acid pretreatment of RH effectively removed lignin and silica, resulting in enzymatic hydrolysis yield of approximately 86.3% under optimal hydrolysis conditions. By using xylose isomerase as well as D-psicose-3-epimerase with borate, glucose present in the RH hydrolysate was converted into D-psicose with a 40.6% conversion yield in the presence of borate. Furthermore, bioethanol (85.4%) and lactic acid (92.5%) were successfully produced from the RH hydrolysate. This study confirmed the high potential of RH as a biorefinery feedstock, and it is expected that various platform chemicals and value-added products can be produced using RH.

Characteristics of fine particles from incense burning at temple premises of Kathmandu Valley, Nepal.

The impact of incense burning on ambient air quality was investigated by measuring the concentrations of fine particles (PM2.5), elemental carbon (EC), organic carbon (OC), and their oxidative potential (OP) at three temple premises in Kathmandu Valley, Nepal. These temples, namely, Bajrabarahi, Bagalamukhi, and Bhadrakali, are located in three distinct environments: forest, residential, and roadside, respectively. During the incense burning event days, the PM2.5 concentration at Bhadrakali (431.4 µgm-3) was significantly higher than that measured at the Bagalamukhi (135.2 µgm-3) and Bajrabarahi (84.7 µgm-3) temple premises. This observation is consistent with the fact that Bhadrakali Temple had the highest intensity of incense burning. Additionally, the temple premises were also influenced by vehicular emissions from transportation facilities. Carbonaceous aerosols significantly increased during incense burning events, indicating that incense burning contributes significantly to the formation of primary and secondary OC. Moreover, the OP of PM2.5 during the incense burning event days was higher compared to non-event days (p < 0.05), suggesting an elevated health risk due to the increased concentration and toxicity of fine particles. These findings highlight the substantial impact of incense burning on air quality in temple premises, emphasizing the need to implement effective strategies to mitigate the associated health risks.

In vitro and in vivo antioxidant and antihyperglycemic potentials of phenolic fractions of Syzygium zeylanicum (L.) DC trunk-bark.

Syzygium zeylanicum L. (DC) (SZL) has been used in antidiabetes treatment for ages. However, the scientific evidence of active agents that have antidiabetic activity and response against biological activities is limited. In this study, the active components of SZL trunk-bark extract (SZL extract) were identified using principal component analysis (PCA), and their antidiabetic activities were assessed. The results indicated that the ethyl acetate fraction (EAF) had the highest concentration of phenolic compounds, antioxidants, and antihyperglycemic activities in the postprandial zebrafish model. The major antioxidant contributors were gallic acid, catechin, epicatechin, ellagic acid, quercetin, caffeine, and apigenin, and their concentrated levels reduced α-amylase inhibitory activity, whereas rutin and ethyl gallate influenced the α-glucosidase inhibitory activity. This study showed the bio-functional properties of active phenolic compounds present in the SZL extract, potentially serving as a functional food to control hyperglycemia.

Value-Added Products from Coffee Waste: A Review.

Coffee waste is often viewed as a problem, but it can be converted into value-added products if managed with clean technologies and long-term waste management strategies. Several compounds, including lipids, lignin, cellulose and hemicelluloses, tannins, antioxidants, caffeine, polyphenols, carotenoids, flavonoids, and biofuel can be extracted or produced through recycling, recovery, or energy valorization. In this review, we will discuss the potential uses of by-products generated from the waste derived from coffee production, including coffee leaves and flowers from cultivation; coffee pulps, husks, and silverskin from coffee processing; and spent coffee grounds (SCGs) from post-consumption. The full utilization of these coffee by-products can be achieved by establishing suitable infrastructure and building networks between scientists, business organizations, and policymakers, thus reducing the economic and environmental burdens of coffee processing in a sustainable manner.

Comparison of physical and chemical characteristics and oxidative potential of fine particles emitted from rice straw and pine stem burning.

Agricultural burning and forest fires are common in Northeast Asia and contribute to the elevation of fine particulate pollution, which greatly affects air quality. In this study, chemical and physical attributes, as well as the oxidative potential of fine particles produced from rice straw and pine stem burning in a laboratory-scale chamber were determined. The burning of rice straw generated notably lower emissions of fine particles and elemental carbon (EC) than did the burning of pine stems. The longer retention of ultrafine particles was observed for rice straw burning likely caused by this material's longer period of initial flaming combustion. Organic carbon (OC), OC/EC, K+/OC, K+/EC, Zn, and alkanoic acid were higher in the fine particles of rice straw burning, while EC, K+/Cl-, Fe, Cr, Al, Cu, and levoglucosan were higher for pine stem burning particles. Chemical data were consistent with a higher hygroscopic growth factor and cloud formation potential and lower amount of agglomerated soot for rice straw burning particles. Rice straw burning particles displayed an oxidative potential seven times higher than that of pine stems.

Morphological and elemental properties of urban aerosols among PM events and different traffic systems.

Morphology and elemental composition of individual fine ambient particles varied among types of PM events and between two different urban environments having different major transportation systems (gasoline/diesel vehicles versus motorcycles). Carbonaceous particles were the most dominant in PM events, whereas S-rich particles were the highest in non-events at urban Gwangju in Korea. The aged soot, semi-volatile organic (SVO), and non-volatile organic (NVO) particles were more abundant in the polluted-long range transport (LTP) event than those in the dust-LTP event and non-event. In the dust-LTP event, the aged mineral dust particles outnumbered the fresh ones, suggesting the mineral dust particles were aged during their long-range transport. At HoChiMinh (HCM) in Vietnam, the fraction of carbonaceous particles was much higher than Gwangju (66% versus 30%) possibly due to more abundant two-stroke motor vehicles at HCM. Of the carbonaceous particles, combustion soot (19%) was the highest, followed by NVO (18%), SVO (17%), and biological particles (11%) at HCM, whereas SVO (11%) and NVO (10%) particles were the highest, followed by combustion soot particles (8%) at Gwangju. The higher fraction of mineral dust particles was also observed at HCM, indicating the sampling site was influenced by dust from unpaved roads and construction sites.

Optical and thermal characteristics of carbonaceous aerosols measured at an urban site in Gwangju, Korea, in the winter of 2011.

UNLABELLED: Carbonaceous components (organic carbon [OC] and elemental carbon [EC]) and optical properties (light absorption and scattering) of fine particulate matter (aerodynamic diameter <2.5 µm; PM2.5) were simultaneously measured at an urban site in Gwangju, Korea, during the winter of 2011. OC was further classified into OC1, OC2, OC3, and OC4, based on a temperature protocol using a Sunset OC/EC analyzer. The average OC and EC concentrations were 5.0 ± 2.5 and 1.7 ± 0.9 µg C m(-3), respectively. The average single-scattering albedo (SSA) at a wavelength of 550 nm was 0.58 ± 0.11, suggesting that the aerosols observed in the winter of 2011 had a local warming effect in this area. During the whole sampling period, "stagnant PM" and "long-range transport PM" events were identified. The light absorption coefficient (babs) was higher during the stagnant PM event than during the long-range transport PM event due to the existence of abundant light-absorbing OC during the stagnant PM event. In particular, the OC2 and OC3 concentrations were higher during the stagnant PM event than those during the long-range transport event, suggesting that OC2 and OC3 might be more related to the light-absorbing OC. The light scattering coefficient (bscat) was similar between the events. On average, the mass absorption efficiency attributed to EC (σEC) was 9.6 m(2) g(-1), whereas the efficiency attributed to OC (σOC) was 1.8 m(2) g(-1) at λ = 550 nm. Furthermore, the σEC is comparable among the PM event days, but the σOC for the stagnant PM event was significantly higher than that for the long-range transport PM event (1.7 vs. 0.5). IMPLICATIONS: Optical and thermal properties of carbonaceous aerosol were measured at Gwangju, and carbonaceous aerosol concentration and optical property varied between "stagnant PM" and "long-range transport PM" events. More abundant light absorbing OC was observed during the stagnant PM event.

Nondestructive characterization of municipal-solid-waste-contaminated surface soil by energy-dispersive X-ray fluorescence and low-Z (atomic number) particle electron probe X-ray microanalysis.

The long-term environmental impact of municipal solid waste (MSW) landfilling is still under investigation due to the lack of detailed characterization studies. A MSW landfill site, popularly known as Dhapa, in the eastern fringe of the metropolis of Kolkata, India, is the subject of present study. A vast area of Dhapa, adjoining the current core MSW dump site and evolving from the raw MSW dumping in the past, is presently used for the cultivation of vegetables. The inorganic chemical characteristics of the MSW-contaminated Dhapa surface soil (covering a 2-km stretch of the area) along with a natural composite (geogenic) soil sample (from a small countryside farm), for comparison, were investigated using two complementary nondestructive analytical techniques, energy-dispersive X-ray fluorescence (EDXRF) for bulk analysis and low-Z (atomic number) particle electron probe X-ray microanalysis (low-Z particle EPMA) for single-particle analysis. The bulk concentrations of K, Rb, and Zr remain almost unchanged in all the soil samples. The Dhapa soil is found to be polluted with heavy metals such as Cu, Zn, and Pb (highly elevated) and Ti, Cr, Mn, Fe, Ni, and Sr (moderately elevated), compared to the natural countryside soil. These high bulk concentration levels of heavy metals were compared with the Ecological Soil Screening Levels for these elements (U.S. Environment Protection Agency) to assess the potential risk on the immediate biotic environment. Low-Z particle EPMA results showed that the aluminosilicate-containing particles were the most abundant, followed by SiO2, CaCO3-containing, and carbonaceous particles in the Dhapa samples, whereas in the countryside sample only aluminosilicate-containing and SiO2 particles were observed. The mineral particles encountered in the countryside sample are solely of geogenic origin, whereas those from the Dhapa samples seem to have evolved from a mixture of raw dumped MSW, urban dust, and other contributing factors such as wind, precipitation, weather patterns, farming, and water logging, resulting in their diverse chemical compositions and the abundant observation of carbonaceous species. Particles containing C and P were more abundant in the Dhapa samples than in the countryside soil sample, suggesting that MSW-contaminated soils are more fertile. However, the levels of particles containing potentially toxic heavy metals such as Cr, Mn, Ni, Cu, Zn, and/or Pb in the Dhapa samples were significant, corroborated by their high bulk concentration levels (EDXRF), causing deep concern for the immediate environment and contamination of the food chain through food crops.

Single-particle characterization of summertime Antarctic aerosols collected at King George Island using quantitative energy-dispersive electron probe X-ray microanalysis and attenuated total reflection Fourier transform-infrared imaging techniques.

Single-particle characterization of Antarctic aerosols was performed to investigate the impact of marine biogenic sulfur species on the chemical compositions of sea-salt aerosols in the polar atmosphere. Quantitative energy-dispersive electron probe X-ray microanalysis was used to characterize 2900 individual particles in 10 sets of aerosol samples collected between March 12 and 16, 2009 at King Sejong Station, a Korean scientific research station located at King George Island in the Antarctic. Two size modes of particles, i.e., PM(2.5-10) and PM(1.0-2.5), were analyzed, and four types of particles were identified, with sulfur-containing sea-salt particles being the most abundant, followed by genuine sea-salt particles without sulfur species, iron-containing particles, and other species including CaCO(3)/CaMg(CO(3))(2), organic carbon, and aluminosilicates. When a sulfur-containing sea-salt particle showed an atomic concentration ratio of sulfur to sodium of >0.083 (seawater ratio), it is regarded as containing nonsea-salt sulfate (nss-SO(4)(2-)) and/or methanesulfonate (CH(3)SO(3)(-)), which was supported by attenuated total reflection Fourier transform-infrared imaging measurements. These internal mixture particles of sea-salt/CH(3)SO(3)(-)/SO(4)(2-) were very frequently encountered. As nitrate-containing particles were not encountered, and the air-masses for all of the samples originated from the Pacific Ocean (based on 5-day backward trajectories), the oxidation of dimethylsulfide (DMS) emitted from phytoplanktons in the ocean is most likely to be responsible for the formation of the mixed sea-salt/CH(3)SO(3)(-)/SO(4)(2-) particles.

Single-particle characterization of indoor aerosol particles collected at an underground shopping area in Seoul, Korea.

UNLABELLED: In this study, single-particle characterization of aerosol particles collected at an underground shopping area was performed for the first time. A quantitative single-particle analytical technique, low-Z particle electron probe X-ray microanalysis, was used to characterize a total of 7900 individual particles for eight sets of aerosol samples collected at an underground shopping area in Seoul, Korea. Based on secondary electron images and X-ray spectral data of individual particles, fourteen particle types were identified, in which primary soil-derived particles were the most abundant, followed by carbonaceous, Fe-containing, secondary soil-derived, and secondary sea-salt particles. Carbonaceous particles exist in three types: organic carbon, carbon-rich, and CNO-rich. A significant number of textile particles with chemical composition C, N, and O were encountered in some of the aerosol samples, which were from the textile shops and/or from clothes of passersby. Primary soil-derived particles showed seasonal variation, with peak values in spring samples, reflecting higher air exchange between indoor and outdoor environments in the spring. Secondary soil-derived, secondary sea-salt, and ammonium sulfate particles were frequently encountered in winter samples. Fe-containing particles, contributed from a nearby subway station, were in the range of about 19% relative abundances for all samples. PRACTICAL IMPLICATIONS: In underground shopping areas, particulate matters can be a considerable health hazard to the workers, shoppers, passersby, and shop-keepers as they spend their considerable time in this closed microenvironment. However, no study on the characteristics of indoor aerosols in an underground shopping area has been reported to our knowledge. This work provides detailed information on characteristics of underground shopping area aerosols on a single particle level.

Combined use of optical and electron microscopic techniques for the measurement of hygroscopic property, chemical composition, and morphology of individual aerosol particles.

In this work, an analytical method for the characterization of the hygroscopic property, chemical composition, and morphology of individual aerosol particles is introduced. The method, which is based on the combined use of optical and electron microscopic techniques, is simple and easy to apply. An optical microscopic technique was used to perform the visual observation of the phase transformation and hygroscopic growth of aerosol particles on a single particle level. A quantitative energy-dispersive electron probe X-ray microanalysis, named low-Z particle EPMA, was used to perform a quantitative chemical speciation of the same individual particles after the measurement of the hygroscopic property. To validate the analytical methodology, the hygroscopic properties of artificially generated NaCl, KCl, (NH(4))(2)SO(4), and Na(2)SO(4) aerosol particles of micrometer size were investigated. The practical applicability of the analytical method for studying the hygroscopic property, chemical composition, and morphology of ambient aerosol particles is demonstrated.

The influence of collecting substrates on the single-particle characterization of real atmospheric aerosols.

This work investigated the influence of three different collecting substrate materials, Ag and Al foils and grids for transmission electron microscopy (TEM grid), on the morphological and chemical compositional analysis of individual particles collected at an underground shopping area in Seoul, Korea. The feasibility of using each substrate in a quantitative single-particle analysis was evaluated by comparing particle morphologies, X-ray spectra, and elemental quantification results obtained for the three substrates. The morphologies and the quality of X-ray spectra for crystalline mineral particles were very similar among the three substrates. However, water-soluble, CNO-rich aerosols showed different morphologies among the three substrates, mainly due to the differences in the hygroscopic properties of the substrates. The quality of the X-ray spectra of the CNO-rich particles was optimal when collected on the TEM grid. To reliably assess the characteristic X-rays of the CNO-rich particles collected on the Ag and Al foils, appropriate data analysis had to be applied. Especially, the X-ray spectra of the CNO-rich particles collected on Al foil required a new background subtraction procedure. The overall relative abundances of the chemical species, obtained from the three collecting substrates, were in good agreement with each other and single-particle characterization of the real aerosol sample was feasible on the different substrates. However, the TEM grid substrate was the most appropriate for single-particle analysis of the water-soluble CNO-rich particles as: (i) it retains the original morphology and size of the particles, (ii) it allows high contrast in the backscattered electron image (BSEI) mode, and (iii) it provides a high peak-to-background ratio (P/B) with small and correctable interferences in the X-ray spectra.