Microbial mechanism of biochar addition to reduce N2O emissions from soilless substrate systems.

The soilless peat-based substrate partially solves the global soil problem in greenhouse vegetable production. However, it still produces serious N2O emissions due to the application of nutrient solutions. The pyrolysis biochar is regarded as an effective measure to reduce soil N2O emissions. However, the effect and mechanism of biochar on N2O emissions from the soilless substrate remain unknown. Therefore, this study set up six treatments by adjusting the ratio of biochar addition of peat-based substrate: 0% (0BC), 2% (2BC), 4% (4BC), 6% (6BC), 8% (8BC) and 10% (10BC) (v/v). The results showed that compared to the control treatment, N2O emissions reduced by 81%, 71%, 51%, 61%, and 75% in the 2BC, 4BC, 6BC, 8BC and 10BC treatments, respectively. In addition, lettuce yield increased by 10% and 7% in the 2BC and 4BC treatments and decreased by 0.5%, 4% and 6% in the 6BC, 8BC and 10BC treatments, respectively. Combining stable isotope technology, qPCR analysis and high-throughput sequencing, five microbial pathways of N2O production, including bacterial and archaea nitrification (BN and AN), denitrification performed by fungi, denitrifier bacteria and nitrifier bacteria (FD, DD and ND), were roughly distinguished. In addition, the extent of N2O reduction was obtained by δ18O vs.δ15NSP map. For all treatments, overall, the DD process (over 50%) was the main process of N2O production and reduction, while ND and AN processes were almost negligible (less 5%). In detail, the decrease of N2O emissions was caused by decreasing the contribution of FD in the 6BC, 8BC and 10BC treatments and reducing the contribution of BN in the 0BC and 2BC treatments. In addition, biochar addition increased the extent of N2O reduction to N2. In summary, the 2% biochar addition presented the greatest extent of N2O reduction to N2 (83%) and the lowest N2O emissions as well as the highest lettuce yields and nitrogen utilization efficiency. Therefore, 2% biochar is deemed the most optimal addition to the peat-based substrate.

Ultrasonic Assisted Extraction of Paclitaxel from Taxus x media Using Ionic Liquids as Adjuvants: Optimization of the Process by Response Surface Methodology.

(1) Background: Ionic liquids (ILs) are considered "green" solvents and have been widely used in the extraction and separation field in recent years; (2) Methods: In this study, some common ILs and functionalized magnetic ionic liquids (MILs) were used as adjuvants for the solvent extraction of paclitaxel from Taxus x media (T. x media) using methanol solution. The extraction conditions of methanol concentration, IL type and amount, solid-liquid ratio, extraction temperature, and ultrasonic irradiation time were investigated in single factor experiments. Then, three factors of IL amount, solid-liquid ratio, and ultrasonic irradiation time were optimized by response surface methodology (RSM); (3) Results: The MIL [C4MIM]FeCl3Br was screened as the optimal adjuvant. Under the optimization conditions of 1.2% IL amount, 1:10.5 solid-liquid ratio, and 30 min ultrasonic irradiation time, the extraction yield reached 0.224 mg/g; and (4) Conclusions: Compared with the conventional solvent extraction, this ultrasonic assisted extraction (UAE) using methanol and MIL as adjuvants can significantly improve the extraction yield, reduce the use of methanol, and shorten the extraction time, which has the potentiality of being used in the extraction of some other important bioactive compounds from natural plant resources.

Extraction, Preconcentration and Isolation of Flavonoids from Apocynum venetum L. Leaves Using Ionic Liquid-Based Ultrasonic-Assisted Extraction Coupled with an Aqueous Biphasic System.

BACKGROUND: Ionic liquids (ILs) are considered as green solvents, and widely applied for the extraction of various compounds. METHODS: The present research focuses on the extraction of flavonoids from Apocynum venetum L. leaves by ultrasound-assisted extraction (UAE). Several major influencing factors were optimized. Then, an aqueous biphasic system (ABS) was applied for further isolation of flavonoids. RESULTS: The flavonoids were mainly distributed in the top phase, while impurities were extracted to the bottom phase. The parameters influencing the extraction, namely type and concentration of salt, temperature, and pH, were studied in detail. Under optimized conditions (72.43% IL extract, 28.57% (NH4)2SO4, 25 °C temperature, pH 4.5), the preconcentration factor and extraction efficiency were found to be 3.78% and 93.35%, respectively. CONCLUSIONS: This simple and efficient methodology is expected to see great use in the extraction and isolation of pharmaceutically active components from medicinal plant resources.

Ionic Liquid-Based Ultrasonic-Assisted Extraction of Secoisolariciresinol Diglucoside from Flaxseed (Linum usitatissimum L.) with Further Purification by an Aqueous Two-Phase System.

In this work, a two-step extraction methodology of ionic liquid-based ultrasonic-assisted extraction (IL-UAE) and ionic liquid-based aqueous two-phase system (IL-ATPS) was developed for the extraction and purification of secoisolariciresinol diglucoside (SDG) from flaxseed. In the IL-UAE step, several kinds of ILs were investigated as the extractants, to identify the IL that affords the optimum extraction yield. The extraction conditions such as IL concentration, ultrasonic irradiation time, and liquid-solid ratio were optimized using response surface methodology (RSM). In the IL-ATPS step, ATPS formed by adding kosmotropic salts to the IL extract was used for further separation and purification of SDG. The most influential parameters (type and concentration of salt, temperature, and pH) were investigated to obtain the optimum extraction efficiency. The maximum extraction efficiency was 93.35% under the optimal conditions of 45.86% (w/w) IL and 8.27% (w/w) Na2SO4 at 22 °C and pH 11.0. Thus, the combination of IL-UAE and IL-ATPS makes up a simple and effective methodology for the extraction and purification of SDG. This process is also expected to be highly useful for the extraction and purification of bioactive compounds from other important medicinal plants.

Research Progress on Hygroscopic Agents for Atmospheric Water Harvesting Systems.

Adsorptive atmospheric water harvesting systems (AWHs) represent an innovative approach to collecting freshwater resources from the atmosphere, with a hygroscopic agent at their core. This method has garnered significant attention due to its broad applicability, strong recycling capacity, and sustainability. It is being positioned as a key technology to address global freshwater scarcity. The core agent's hygroscopic properties play a crucial role in determining the performance of the AWHs. This article provides a comprehensive review of the latest advancements in hygroscopic agents, including their adsorption mechanisms and classifications. This study of hygroscopic agents analyzes the performance and characteristics of relevant porous material composite polymer composites and plant composites. It also evaluates the design and preparation of these materials. Aiming at the problems of low moisture adsorption and desorption difficulty of the hygroscopic agent, the factors affecting the water vapor adsorption performance and the method of enhancing the hygroscopic performance of the material are summarized and put forward. For the effect of hygroscopic agents on the volume of water catchment devices, the difference in density before and after hygroscopicity is proposed as part of the evaluation criteria. Moisture absorption per unit volume is added as a performance evaluation criterion to assess the effect of hygroscopic agents on the volume of water collection equipment. The article identifies areas that require further research and development for moisture absorbers, exploring their potential applications in other fields and anticipating the future development direction and opportunities of moisture-absorbing materials. The goal is to promote the early realization of adsorptive atmospheric water harvesting technology for large-scale industrial applications.

Insights into production and consumption processes of nitrous oxide emitted from soilless culture systems by dual isotopocule plot and functional genes.

Soilless culture systems (SCS) play an increasing role in greenhouse vegetable production. In the SCS, soilless substrates serve as the major substitute for soil, supplying nutrients to plants but releasing greenhouse gases into the atmosphere. Remarkably, there is a serious problem of N2O emission due to excessive input of N fertilizer. However, the microbial processes of N2O production and consumption in soilless substrates have been rarely studied resulting in difficultly interpreting for its global warming potential. Therefore, these pathways from two classic soilless substrates under two irrigation patterns were investigated by stable isotope technology combined with qPCR analysis in present study. The results according to the dual isotopocule plot of δ15NSP vs. δ18O showed that the mean contribution of denitrification and the mean extent of N2O reduction of case i (Reduction-Mixing) were 26.2 and 81.2 % for the treatment of peat based substrate under drip irrigation (PD), 47.7 and 70.3 % for the treatment of coir substrate under drip irrigation (CD), 29.0 and 80.8 % for the treatment of peat based substrate under tidal irrigation (PT), and 50.8 and 47.4 % for the treatment of coir substrate under tidal irrigation (CT). These results were also further confirmed by the abundance of major functional genes including AOA amoA, nirK and nosZ. Altogether, N2O emission and its microbial processes are determined by substrate types instead of irrigation patterns. For detail, denitrification dominated in the peat based substrate and nitrification dominated in the coir substrate. Compared to the coir substrate, the peat based substrate had higher abundance of functional genes and stronger denitrification and thus generated more N2O. For the two soilless substrates, moreover, the microbiome replaced the mineral N content as the limiting factor for N2O emission. In the SCS, in summary, the two soilless substrates play an important role in tomato growth, but might suffer from inorganic nutrient surplus and microbial shortage. More importantly, the combined analysis of N2O isotopocule deltas and functional genes is a robust tool and provides reliable conclusions for clarifying the microbial processes of N2O production and consumption, thus it is also recommended for use in environments other than soilless substrates.

Nitrogen transformation and its microbial mechanism under co-composting of biogas slurry with garden waste.

Large amount of garden waste is consecutively produced in China every year. The composting with urea and microbial inoculum makes it possible to dispose garden waste in large quantities. However, composting accompanies with serious nitrogen loss and environmental problems. The biogas slurry contains considerable nitrogen nutrients and microorganisms, which theoretically could be used as alternative to urea and bacteria to reduce nitrogen loss, respectively. We set up three treatments of biogas slurry + garden waste (GB), biogas slurry + garden waste + urea (GBU), and biogas slurry + garden waste + urea + microbial inoculum (GBUM) to investigate the decomposition, nitrogen conversion and nitrogen loss in the co-composting process. The results showed that the high tempe-rature period of GB treatment was longer and more stable compared to that of GBU and GBUM treatments. The pH and EC value of GB treatment would benefit composting process and generated products with the highest germination index (GI) (221.8%). In addition, NH3 and N2O emission rates in the GB treatment were 2.59 mg·kg-1·d-1 and 3.65 µg·kg-1·d-1, respectively, being 99.0% and 50.0% lower than that in the GBU treatment and 99.4% and 40.7% lower than that in the GBUM treatment. The results of δ18O vs. δ15NSP dual isotopocule plots approach analysis showed that the GB and GBU treatments were dominated by denitrification, and that the contribution of denitrification was higher in the GB treatment. In contrast, the GBUM treatment was dominated by nitrification. The degree of N2O reduction in GB treatment (83.7%) was higher than the other two treatments. It was clear that GB treatment had the best maturity and lowest nitrogen loss in all treatments by enhancing the N2O reduction process during denitrification to reduce N2O emission. In conclusion, the biogas slurry and garden wastes could be directly co-composted without the limitation of C/N and microbial addition. The co-composting method could protect the environment and save resources leading to the recycling of waste in actual production.

Steam-Exploded Pruning Waste as Peat Substitute: Physiochemical Properties, Phytotoxicity and Their Implications for Plant Cultivation.

Peat is a nonrenewable resource that we are using at alarming rates. Development of peat alternative from pruning waste (PW) could be a cost- and environment-friendly way of disposal. Steam explosion (SE) is a commonly used pretreatment of lignocellulosic biomass, but its impact on the properties of PW as a growing substrate is largely unknown. To address this issue, PW was treated using five SE temperatures (160, 175, 190, 205 and 220 °C) and three retention times (1, 3 and 5 min) and evaluated for key traits of growing substrate. Results indicate that bulk density, total porosity, EC, total carbon, and concentration of phytotoxins including phenol, flavonoid, and alkaloid significantly increased or tended to increase with increasing temperature and/or retention time. A reversed trend was observed for water-holding capacity, pH, content of hemicellulose and lignin, and germination index. Cation exchange capacity and total N showed minimal response to SE. Steam explosion had inconsistent impacts on acid soluble nutrients. Phytotoxicity was a major factor limiting the use of SE-treated PW as growing substrate. Higher pretreatment severity led to higher phytotoxicity but also facilitated subsequent phytotoxicity removal by torrefaction. Pruning waste treated by SE and torrefaction under certain conditions may be used as peat substitute for up to 40% (v/v).

Phytotoxicity of Chemical Compounds from Cinnamomum camphora Pruning Waste in Germination and Plant Cultivation.

Much previous research has indicated most composts of pruning waste are characterized by potential phytotoxicity, it is highly correlated with the chemical compounds of raw materials. Cinnamomum camphora, a common kind of pruning waste in Southeast Asia and East Asia, is characterized by intense bioactivities due to complex chemical components. This study investigated the potential phytotoxicity of C. camphora pruning waste in light of germination and higher plant growth. C. camphora extracted from leaves completely inhibited seed germination and still showed suppression of root elongation at an extremely low dosage. C. camphora extract also displayed significant inhibition of nutrient absorption in tomato seedlings, including moisture, available nutrients (N, P and K) and key microelements (Fe, Mn, Zn and S). The gene expression of aquaporins and transporters of nitrate and phosphate was significantly up-regulated in roots. This could be regarded as a positive response to C. camphora extract for enhancing nutrient absorption. Moreover, the severe damage to the plasma membrane in roots caused by C. camphora extract might seriously affect nutrient absorption. Camphor is the main component of the C. camphora extract that may induce the phytotoxicity of plasma membrane damage, resulting in the inhibition of nutrient absorption and low biomass accumulation. This study provided a new understanding of the ecotoxicological effects of C. camphora pruning waste, indicating that the harmless disposal of pruning waste requires much attention and exploration in the future.

Superheated steam as carrier gas and the sole heat source to enhance biomass torrefaction.

Superheated steam (SHS) has been used as a carrier gas for pressurized steam torrefaction, steam explosion or pyrolysis, but is barely used as a heat source. However, SHS is superior in thermal capacity and heat transfer coefficient resulting in even heating and fast heating rates. Therefore, this work applied SHS as the sole heat source for torrefaction at ambient pressure. A setup was specially designed and capable of heating wood shavings at a rate >120 °C•min-1. Solid products were analyzed in many aspects and demonstrated the enhanced organics conversion owing to SHS torrefaction. Torrefied biomass was comparable to slow pyrolysis char in fuel quality and superior to that of conventional torrefactions. Moreover, SHS torrefaction was super-timesaving. A coal-like product (HHV of 27.84 MJ•kg-1) was achieved in only 15 min at 350 °C. Overall, SHS torrefaction boosted biomass densification and gaveriseto greater production efficiency.

Fuel properties and combustion behaviors of fast torrefied pinewood in a heavily loaded fixed-bed reactor by superheated steam.

Superheated steam (SHS) was capable of fast and uniformly torrefying heavily loaded biomass. This work detailedly investigated the torrefied biomass in terms of fuel property and combustion behavior. The reactor chamber (300 ml) was fully loaded with pinewood pellets (160 g). Overall residence times were 20, 40 and 60 min (including preheating and holding periods) under 225, 275 and 325 °C. Biomass was estimated by elements, TG, FTIR, HHV, fuel property, combustion and pyrolysis behaviors, combustion kinetics and moisture reabsorption. Holding period as short as 2 min at 325 °C with a heating rate of 15 °C‧min-1 was found to enhance energy density by 45% and generated homogeneous coal-like products with HHV of 26.76 MJ‧kg-1. Fixed carbon content increased to 64.84 wt%. The combustion activation energy increased to 79.66 kJ‧mol-1. Combustion indices and behaviors indicated that torrefied biomass had benign characteristics either for co-firing or as fuel. All suggests good potential of SHS torrefaction to obtain fuel alternatives.

Rooting ability of rice seedlings increases with higher soluble sugar content from exposure to light.

Rooting ability of rice seedling for mechanical transplanting has a large impact on grain yield. This study explored the relationship between endogenous soluble sugar content and rooting ability of rice seedlings. We placed 15-day-old rice seedlings in controlled environment cabinets with stable light and sampled after 0, 3, 6, 9, 12, and 24 hours of light to measure their soluble sugar content, nitrate content, starch content, soluble protein content and rooting ability. The soluble sugar content of the rice seedlings before rooting increased rapidly from 65.1 mg g-1 to 126.3 mg g-1 in the first 9 hours of light and then tended to stabilize; however, few significant changes in the other physiological indices were detected. With the light exposure time increasing from 3 hours to 12 hours, the rooting ability measured with fresh weight, dry weight, total length, and number of new roots increased by 91.7%, 120.0%, 60.6% and 30.3%, respectively. Rooting ability was related more closely to soluble sugar content than to nitrate-nitrogen content of rice seedlings before rooting and their correlation coefficients were 0.8582-0.8684 and 0.7045-0.7882, respectively. The stepwise regression analysis revealed that the soluble sugar content before rooting explained 73.6%-75.4% of the variance, and the nitrate-nitrogen content explained an additional 7.3%-14.2% of the variance in rooting ability, indicating that compared with nitrate-nitrogen content, soluble sugar content of rice seedlings before rooting was more dominant in affecting rooting ability. This study provides direct evidence of the relationship between the rooting ability and endogenous soluble sugar content of rice seedlings.

Author Correction: Effects of applying ramie fiber nonwoven films on root-zone soil nutrient and bacterial community of rice seedlings for mechanical transplanting.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Effects of applying ramie fiber nonwoven films on root-zone soil nutrient and bacterial community of rice seedlings for mechanical transplanting.

Raising rice seedlings in flat trays has become the main method for mechanized transplanting of rice in China. However, seedling blocks raised by this method were easily cracked in practice, and this problem can be solved by padding a thin ramie fiber nonwoven film on the bottom surface of seedling tray. This study was conducted to determine the effects of this film on root-zone environment of rice seedlings. The results showed that on the 10th day after sowing, the soil inorganic nitrogen, especially nitrate nitrogen, content in the root-zone of the film treatment were considerably higher than in the no-film treatment, in contrast, the soil organic matter content was lower in the film treatment, and by the 20th day, the gap between treatments was enlarged. After applying the film, the Chao 1 index and Shannon index values for the soil bacterial community diversity decreased, and the rice seedlings were shorter, had higher root/shoot ratios, lower nitrate contents, and higher soluble sugar contents. We conclude that application of the ramie fiber nonwoven film resulted in substantial changes in the soil nutrient and bacterial community in root-zone in a short time, which significantly impacted the growth and development of rice seedlings.

Assessment of the cytotoxicity of ionic liquids on Spodoptera frugiperda 9 (Sf-9) cell lines via in vitro assays.

Cytotoxicity studies are important tools for the assessment of the toxicity of ionic liquids (ILs). In the present study, the cytotoxicity of eleven ILs against Spodoptera frugiperda 9 (Sf-9) cell lines were evaluated via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. The effect on cellular morphology, ultrastructural morphology, and nuclear morphology induced by 1-ethyl-3-methylimidazolium bromide ([C2mim][Br]) was studied via inverted light microscopy observation, acridine orange staining, and transmission electron microscope (TEM) analysis, respectively. The effect on cell DNA fragmentation, cell apoptosis and cell cycle induced by [C2mim][Br] was also investigated via DNA agarose gel electrophoresis and flow cytometry analysis, respectively. The results showed that the cytotoxic effect of ILs on Sf-9 cells was related to the IL structures, concentrations, and length of exposure. The morphological features of apoptosis induced by [C2mim][Br] such as cell shrinkage and convolution, apoptotic bodies, pyknosis, and karyorrhesis were observed. All these phenomena confirmed that Sf-9 cells exposed to [C2mim][Br] died via apoptosis. This study complements the current knowledge about the cytotoxic properties of ILs on insect cells and highlights the mechanism by which ILs kill these cells. Furthermore, it provides a basis for further studies on the future applications of ILs as insecticides.

Extraction of Oil from Flaxseed (Linum usitatissimum L.) Using Enzyme-Assisted Three-Phase Partitioning.

In this study, enzyme-assisted three-phase partitioning (EATPP) was used to extract oil from flaxseed. The whole procedure is composed of two parts: the enzymolysis procedure in which the flaxseed was hydrolyzed using an enzyme solution (the influencing parameters such as the type and concentration of enzyme, temperature, and pH were optimized) and three-phase partitioning (TPP), which was conducted by adding salt and t-butanol to the crude flaxseed slurry, resulting in the extraction of flaxseed oil into alcohol-rich upper phase. The concentration of t-butanol, concentration of salt, and the temperature were optimized to maximize the extraction yield. Under optimized conditions of a 49.29 % t-butanol concentration, 30.43 % ammonium sulfate concentration, and 35 °C extraction temperature, a maximum extraction yield of 71.68 % was obtained. This simple and effective EATPP can be used to achieve high extraction yields and oil quality, and thus, it is potential for large-scale oil production.