OH Content Research Articles

Sustainable strategy for lignin etherification and its promotion of anti-UV aging PLA biocomposite

Achieving efficient modification of both phenolic (Phe)-OH and aliphatic (Aliph)-OH groups in lignin simultaneously via sustainable method, remained a significant challenge. In this study, a series of highly hydroxyl-substituted alkali lignin phenyl propylene ketone ethers (ALK) were obtained under 50 °C without any by-products via the mild and sustainable hydroxyl-yne click reaction method. Notably, phenolic (Phe)-OH content of lignin decreased from 4.12 mmol g−1 to 0.07 mmol g−1 with a conversion rate of 98 %, while the aliphatic (Aliph)-OH content of lignin decreased from 2.57 mmol g−1 to 0.10 mmol g−1 with a conversion rate of 96 %. Owing to the efficient etherification, ALK showed excellent organic solvent (such as trichloromethane, DCM, THF, and acetone) solubility, which thereby improving the interfacial compatibility between ALK and PLA matrix. 3 wt% ALK obviously enhanced the mechanical properties of ALK/PLA biocomposite films, with the yield strength, breaking strength, and Young’s modulus improving by 114.2 %, 30.7 % and 250.2 %, respectively. Additionally, due to the newly introduced vinyl ether bonds (−C–O–CC–) in ALK by hydroxyl-yne click reaction, only 1 % ALK could endow ALK/PLA biocomposite with excellent UV shielding (100 %), high transmittance (84.3 %) and Anti-UV aging property. The yield strength and Young’s modulus represented an increase of 209 % and 86 %, respectively, even after 3 h of UV-irradiation. This study presents an environmentally friendly lignin functionalization method that unleashes the inherent Anti-UV aging properties of lignin, opening new avenues for the development of high-performance lignin-based composites.

Volatile systematics in terrestrial igneous apatite: from microanalysis to decoding magmatic processes

Apatite has been recognized as a robust tool for the study of magmatic volatiles in terrestrial and extraterrestrial systems due to its ability to incorporate various volatile components and its common occurrence in igneous rocks. Most previous studies have utilized apatite to study individual magmatic systems or regions. However, volatile systematics in terrestrial magmatic apatite formed under different geological environments has been poorly understood. In this study, we filtered a large compilation of data for apatite in terrestrial igneous rocks (n > 20,000), categorized the data according to tectonic settings, rock types, and bulk-rock compositions, and conducted statistical analyses of the F–Cl–OH–S–CO2 contents (~ 11,000 data for halogen and less for other volatiles). We find that apatite from volcanic arcs preserves a high Cl signature in comparison to other tectonic settings and the median Cl contents differ between arcs. Apatite in various types and compositions of igneous rocks shows overlapping F–Cl–OH compositions and features in some rock groups. Specifically, apatite in kimberlite is characterized as Cl-poor, whereas apatite in plutonic rocks can contain higher F and lower Cl contents than the volcanic counterparts. Calculation using existing partitioning models indicates that apatite with a high OH (or F) content does not necessarily indicate a H2O-rich (or H2O-poor) liquid because it could be a result of high (or low) magma temperature. Our work may provide a new perspective on the use of apatite to investigate volatile behavior in magma genesis and evolution across tectonic settings, volatile recycling at subduction zones, and the volcanic-plutonic connection.

Mechanistic insights into δ-MnO2/biochar–activated persulfate-treated wastewater containing antibiotics and heavy metals: Nonradical pathway and pivotal role of Cu(Ⅱ) at low temperature

Herein, we present a high efficiency system based on biochar loaded with layered manganese dioxide to remove tetracycline and heavy metals from livestock wastewater. Under the optimal conditions, the degradation efficiencies of TC in the δ-MnO2/BC/PS system were 85.5% at 25 °C and 38.5% at 5 °C. Radical quenching experiments revealed that radical reactions in the δ-MnO2/BC/PS system were weak under 15 °C. Adsorption degradation experiments showed that the system maintained good adsorption performance at 5 °C. Galvanic cell experiments and cyclic voltammetry showed that the δ-MnO2/BC material had good electrochemical activity and high stability in response to temperature, indicating that TC was degraded by a nonradical pathway that was not limited by temperature, such as electron transfer. Copper ion was important coadsorbent and coactivator of the reaction system. Furthermore, FTIR, XPS, and X-ray diffraction (XRD) analyses showed that Cu(II) in the system was involved in changing the manganese valence state in the δ-MnO2/BC material and increasing the –OH content of BC. Comparison of the different products generated during metabolic testing revealed that the reaction pathway of the system at low temperature (5 °C) differed from that at normal temperature (25 °C). The δ-MnO2/BC material demonstrated good removal ability for antibiotics and heavy metals at normal and low temperatures in actual biogas slurry. The study provides insight for improving the efficiency of environmentally friendly treatments of aquaculture wastewater in cold regions, which is of great significance for resource utilization.

Thermoelectric engineered cementitious composites with low thermal conductivity for efficiency improvement of buildings

Thermoelectric cement-based materials are getting noticed for their ability to convert heat into electricity and reduce surface temperatures. This study developed thermoelectric ultra-lightweight engineered cementitious composites (ULW-ECC) with low thermal conductivity (0.478 – 0.668 W/(mK)) and low density (1003 – 1157 kg/m3). Carbon fibre (CF) of varying lengths (1 – 20 mm) and concentrations (0, 0.5, and 1.0 vol%) were incorporated, and the mechanical, electrical conductivity and thermoelectric performance of the composite were thoroughly examined. Additionally, the impact of saturation and drying treatment on thermoelectric conversion efficiency was assessed. The results revealed that the inclusion of mineral admixtures and fly ash cenospheres within the composite could decrease the content of OH– ions in pore solution due to the pozzolanic effect. This phenomenon led to the creation of a high-performance p-type ionic thermoelectric effect, with a Seebeck coefficient of 3.14 mV/℃. Moreover, treatments involving saturation and drying were found to respectively enhance and diminish conversion efficiency. Incorporating CF into ULW-ECC generates an ionic-electronic thermoelectric effect through the collaborative interaction of metal cations and positive hole carriers from both the pore solution and CF, respectively. Thermoelectric conversion efficiency varied with CF length and dosage, with a peak improvement in the Seebeck coefficient reaching 5.9 mV/℃. However, a sharp decline occurred when a continuous conductive network was formed.

Exploring the promoting effect of nitrilotriacetic acid on hydroxyl radical and humification during magnetite-amended composting of sewage sludge

The OH production by adding magnetite (MGT) alone has been reported in composting. However, the potential of nitrilotriacetic acid (NTA) addition for magnetite-amended sludge composting remained unclear. Three treatments with different addition [control check (CK); T1: 5 % MGT; T2: 5 % MGT + 5 % NTA] were investigated to characterize hydroxyl radical, humification and bacterial community response. The NTA addition manifested the best performance, with the peak OH content increase by 52 % through facilitating the cycle of Fe(Ⅱ)/Fe(Ⅲ). It led to the highest organic matters degradation (22.3 %) and humic acids content (36.1 g/kg). Furthermore, NTA addition altered bacterial community response, promoting relative abundances of iron-redox related genera, and amino acid metabolism but decreasing carbohydrate metabolism. Structural equation model indicated that temperature and Streptomyces were the primary factors affecting OH content. The study suggests that utilizing chelators is a promising strategy to strengthen humification in sewage sludge composting with adding iron-containing minerals.

Modulation of physicochemical and antioxidant properties of Pickering emulsions using colloidal lignin particles based on kraft softwood and hardwood acetone fractions

Colloidal lignin particles (CLPs) emerge as a sustainable alternative to traditional, fossil-based emulsion stabilizers. However, effectively outperforming the conventional ingredients requires addressing the challenges posed by lignin heterogeneity and structural complexity. In this study, one-step acetone fractionation was applied to softwood and hardwood kraft lignins to tackle the issue. The resulting soluble (AS) and insoluble (AI) fractions, along with the pristine lignins, underwent thorough characterization and were used to create CLPs through the hydrotropic precipitation. The acetone fraction-derived CLPs were tested for the first time as Pickering stabilizers. Notably, a strong correlation emerged between the structural traits of each lignin sample and the properties of the resulting Pickering emulsions. Such correlation allowed for a fine-tuning of their physicochemical and antioxidant features. The AS fractions, characterized by higher phenolic OH content and lower molecular weight, led to CLPs with larger sizes and reduced hydrophilic character compared to those derived from AI- and pristine lignins. The fraction-derived CLPs exhibited superior emulsifying capacity and imparted long-term stability to the formed emulsions. Moreover, the resulting Pickering emulsions showed high potential as antioxidant agents, proving their ability as multifunctional systems. Overall, this work demonstrates how the unique properties of lignin can be selectively enhanced through acetone fractionation method and seamlessly transferred to Pickering emulsions. This advancement promotes the use of lignin in high-value-added sectors such as cosmetics and personal care.

Effect of ionic liquid-surfactant compound solutions on the wettability and functional groups of coal

In order to investigate the feasibility of ionic liquid-surfactant compound solutions for coal dust suppression, three ionic liquids and sodium alpha-olefin sulfonate (AOS) were selected to be compounded respectively. The compound solutions were optimized by surface tension tests and coal dust settling experiments, and FTIR and SEM tests were carried out on coal samples treated with the optimum wetting agent. The results show that when the concentration is 0.3 wt%, and the ratio of [Bmim][Cl]/AOS is 4:6, the wetting rate of compound solution is the maximum. The content of hydrophilic functional groups OH…O and C-O in the coal samples increases significantly, and the degree of benzene ring substitutions is elevated; while hydrophobic functional groups –CH, aromatic ring C = C, and benzene ring 3 substitutions (3H) are destroyed by dissolution. The micromorphology of the coal surface changes with the appearance of many cracks and pores and an increase in surface roughness. [Bmim]+ can adsorb on the drain absorption points on the coal surface by electrostatic effect, turning them into water absorption sites and attracting the surrounding AOS molecules to arrange the composite adsorption layer more closely. These results can contribute to the development of novel wetting agents with specific structures and provide theoretical guidance for the reduction of coal dust concentrations.

Metallogenic Difference between the Late Aptian Nansu and Aishan Pluton in Jiaodong: Constraints from in Situ Apatite Elemental and Nd Isotopic Composition

A series of Mo-polymetallic deposits have been developed in the Jiaodong Peninsula. Notably, these Mo-dominant deposits formed essentially during the same period as the well-known world-class Au deposits in this area, hinting at a potentially unique geological correlation between them. Therefore, conducting thorough research on Mo deposits in Jiaodong holds significant importance in exploring the area’s controlling factors of Mesozoic metal endowments. To reveal the petrogenesis and metallogenic potentials of Mo-fertile and ore-barren granitoid, apatite grains from the Late Aptian Nansu granodiorite and Aishan monzogranite are investigated in this study. Detailed petrographical observations, combined with in situ analysis of electron probe micro-analyzer (EPMA) and Laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), have been conducted on apatite grains from the Nansu and Aishan plutons. This comprehensive analysis, encompassing both major and trace elements as well as isotopic characteristics of apatite, aims to elucidate the metallogenic differences within the late Early Cretaceous granitoids of Jiaodong. The results reveal that the apatite grains across all samples belong to fluorapatites, suggesting their magmatic origin. Additionally, chondrite-normalized rare earth element (REE) patterns of apatites in ore-fertile and ore-barren granitoids exhibit a “right-leaning” trend, characterized by relative enrichments in light REEs and depletions in heavy REEs. Both the Nansu and Aishan plutons exhibit moderately negative Eu anomalies (with averages δEu values of 0.44 and 0.51, respectively), along with slightly positive Ce anomalies (averaging δCe values of 1.08 and 1.11, respectively). A negative correlation is observed between their δEu and δCe values, indicating that the parental magmas of ore-fertile and ore-barren granitoids were formed in a relatively oxidizing environment. The calculated apatite OH contents for the Nansu pluton range from 0.26 to 1.38, while those for the Aishan pluton vary between 0.24 and 1.51, indicating comparable melt H2O abundances. Consequently, the results suggest that neither the oxygen fugacities nor the water contents of the parental magma can account for the metallogenic differences between Nansu and Aishan plutons. The apatite in the Nansu pluton exhibits a higher Ce/Pb ratio and a relatively lower Th/U ratio, indicating the involvement of a greater volume of fluids in the magmatic evolution process of this ore-bearing granitoid. Apatite grains sourced from the Nansu and Aishan plutons exhibit εNd(t) values ranging from −16.63 to −17.61 (t = 115.7 Ma) and −17.86 to −20.86 (t = 116.8 Ma), respectively. These results suggest that their parental magmas primarily originated from the partial melting of Precambrian metamorphic basement rocks within the North China Craton, with a minor contribution from mantle-derived materials. Additionally, the presence of mafic microgranular enclaves in both the Nansu and Aishan plutons indicates that both have undergone magma mixing processes. The binary diagrams plotting the ratios of Ba/Th, Sr/Th, and U/Th against La/Sm demonstrate that apatite grains of ore-fertile granitoid exhibit a distinct trend towards sediment melting. This suggests the potential incorporation of sedimentary materials, particularly those rich in molybdenum, into the magmatic source of the Nansu pluton, ultimately leading to the occurrence of molybdenum mineralization.

Mixed matrix membranes based on morpholinium-functionalized CardoPES and MgAl-LDH: Structures, properties and electrodialysis performance

A simple, inexpensive, and effective method based on the MMMs prepared from morpholinium-functionalized CardoPES and MgAl-LDHs is proposed to improve the ED capabilities of AEMs. The microphase separation and ED performance of mixed matrix AEMs were substantially enhanced by LDH introduction, which was attributed to the surface OH groups of the LDH nanosheets; these interactions induced polymer chain self-assembly. The AEM with 8 % LDH exhibited the highest salt flux (92.5 mg/m2·s) during ED, which was 19.6 % and 14.1 % greater than those of the commercial Type 10 membrane and the mixed matrix AEM, respectively. Hydrogen bonding interactions and the ED capabilities of the AEMs were readily regulated by adjusting the feed ratios of the LDH and morpholinium groups. With increasing LDH content, the Rm and ED performance increased, while the hydrophilicity and mechanical properties initially decreased. When the OH content of an LDH nanosheet was higher than the morpholinium content, as the LDH content increased, the Rm and ED performance decreased, while the hydrophilicity and mechanical properties increased, which may be attributed to internal structural discrepancies between the complete and incomplete core-shell structures of the AEMs caused by different hydrogen bonding patterns.

Reduced Surface Trap States of PbS Quantum Dots by Acetonitrile Treatment for Efficient SnO2-Based PbS Quantum Dot Solar Cells.

The solution-phase ligand-exchange strategy offers a simple pathway to prepare PbS quantum dots (QDs) and their corresponding solar cells. However, the production of high-quality PbS QDs with reduced surface trap state density for efficient PbS QD solar cells (QDSCs) still faces challenges. As the hydroxyl group (-OH) has been demonstrated to be the primary source of the surface trap states on PbS QDs in the general oleic acid method, here, we present an effective and facile strategy for reducing the surface -OH content of PbS QDs by using acetonitrile (ACN) as precipitant to wash the surface of QDs, which significantly decreases the trap state density and enables the preparation of superior PbS QDs. The resulting solar cell with an ITO/SnO2/n-PbS/p-PbS/Au structure obtained an improved photoelectric conversion efficiency (PCE) from 8.53 to 10.49% with an enhanced air storage stability, realizing a high PCE for SnO2-based PbS QDSCs.

Elucidating the effects of −OH content on phase transition and Li-ion transport of anti-perovskite solid electrolytes

Anti-perovskite materials such as Li2(OH)Cl have garnered considerable interest as solid electrolytes due to their numerous advantages. However, the low ionic conductivity of the orthorhombic Li2(OH)Cl near room temperature presents a significant challenge for the application. In this study, we intricately modulate the −OH content in Li2(OH)Cl through a controlled heat treatment process. This method effectively increases the cubic phase content and lowers the phase transition temperature, thereby enhancing the ionic conductivity at 30 °C by more than an order of magnitude. Theoretical calculations illustrate that the removal of −OH content significantly reduces the barrier for phase transition, leading to substantial alterations in the Li-ion transport pathway and migration barrier. Furthermore, LiHClO-600 demonstrates exceptional resistance to lithium reduction and is compatible with lithium metal and LiFePO4, rendering it a viable solid electrolyte for batteries. Both experimental findings and theoretical calculations cohesively highlight the pivotal role of −OH content in driving phase transition and facilitating Li-ion transport in anti-perovskite solid electrolytes, paving the way for their potential utilization in all-solid-state batteries.

Hygroscopicity of nitrocellulose with different nitrogen content

AbstractResearch on the hygroscopic behavior of NC is essential because it affects the mechanical properties, combustion properties, and safe storage of NC‐based products. In this study, Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) are used to characterize the chemical structure, crystal structure, and microscopic morphology of NC, respectively. The moisture adsorption isotherms of NC fibers with different nitrogen content are determined by dynamic vapor sorption (DVS) and fitted with Hailwood‐Horrobin (H−H) and Guggenheim‐Anderson‐de Boer (GAB) models. The specific surface area and surface energy of NC are also measured by inverse gas chromatography (IGC). The results show that as the nitrogen content of NC increases, the intensity of the −OH characteristic absorption peak is weakened, the crystallinity does not change much, the number of cracks and pores on the NC fiber surface increases, and the equilibrium moisture content (EMC) of the NC decreases in general. In addition, the fitting results based on the H−H and GAB models show that, under low humidity conditions, the EMC value of NC is determined by the adsorbed water content of the monolayer, which is mainly related to the −OH content in NC. However, with the increase of humidity, the EMC value of NC is gradually determined by the multilayer adsorbed water content, which is influenced by both the nitrogen content and the fiber cleavage structure. Meanwhile, the IGC results show that the surface energy of the NC consists mainly of the dispersive surface energy (values >46 mJ m−2), with the specific surface energy contributing approximately 25 mJ m−2. The total surface energy of NC and the bonding strength between NC molecules and water molecules decrease with increasing nitrogen content.

Kinetics and mechanism of (re)hydroxylation in fired clay minerals

AbstractThree types of smectite with various crystallochemical compositions and interlayer cations as well as kaolinite and illite were fired at 800°C and 650°C and tested for their rehydroxylation's (RHX) potential and kinetics in the presence of water vapor at 200°C–350°C. A dehydroxylated structure of 2:1 Al‐rich mineral with the interlayer pillared by a large cation (like K+ or Cs+) is wide enough to allow H2O diffusion which results in advanced RHX, that is, restoring up to several tens of percent of the original OH content. Such 2:1 layer structures (beidellite, illite) do not follow the time‐to‐the‐quarter (TTTQ) kinetics during RHX and show a non‐Arrhenius behavior for isothermal RHX. Because TTTQ kinetics is assumed in an RHX dating of ceramic artifacts in archaeometry, fired‐clay ceramics prepared from material dominated by Al‐rich 2:1 minerals was found unfeasible for RHX dating.Kaolinite and Mg2+‐ or Ca2+‐exchanged smectites show the Arrhenius behavior and follow the TTTQ kinetics of RHX, resulting in apparent Ea increase with the progress of reaction (up to α ∼0.2) of ∼20–50 kJ/mol in beidellite and 15–35 kJ/mol in montmorillonite. We suggest using ‘hydroxylation’ rather than ‘rehydroxylation’ for structurally‐disordered fired clays gaining OH groups in an unknown position.

Novel approach for corn straw biorefineries: Production of xylooligosaccharides, lignin and ethanol by nicotinic acid hydrolysis and pentanol pretreatment

The productive separation and conversion of corn straw offers significant prospects for the economic viability of biorefineries centered on straw resources. In this work, a graded utilization method was proposed to produce xylo-oligosaccharides (XOS), ethanol and lignin from corn straw by nicotinic acid (NA) hydrolysis and water/pentanol pretreatment. A XOS yield of 52.6 % was achieved under optimized conditions of 100 mM NA, 170 °C and 30 min. The solid residue was directly treated with water/pentanol, achieving a lignin removal rate of 79.7 %, and the total XOS yield was improved to 62.6 %. The lignin recovered from pentanol had a high purity of 97.6 %, with high phenolic OH content. Simultaneous saccharification and fermentation of final residue resulted in an ethanol yield of 92.0 %, which yielded 55.3 g/L ethanol. Thus, NA hydrolysis and water/pentanol pretreatment provided an efficient, environmentally friendly approach to fractionate corn straw for the co-production of XOS, ethanol, and lignin.

Elm wood (Ulmus rubra) vacuum drying at 40 °C studied by time domain nuclear magnetic resonance (TD-NMR)

Abstract The time domain nuclear magnetic resonance (TD-NMR) technique was employed to distinguish various water states, and the moisture migration during Elm wood (Ulmus rubra) heartwood vacuum drying was quantitatively analyzed. The transverse relaxation time (T2) was employed to establish the correlation between drying time and moisture migration. Additionally, the longitudinal relaxation time (T1) was utilized to identify two types of water states within the cell wall: OH bound water (B-water) and more freely bound water (C-water). Meanwhile, the changes in these two types of bound water during the drying were investigated. The results demonstrated an exponential decrease in the content of OH bound water and more freely bound water with drying time. OH bound water within the cell wall predominated, with only a small portion of more freely bound water experiencing migration loss when the moisture content (MC) dropped below 20 %. Furthermore, OH bound water exhibited higher migration rate compared to more freely bound water at 10–20 % MC, while the motion of OH bound water molecules became highly restricted and stronger binding to cell walls than more freely bound water at a MC level of below 10 %. These findings yield a theoretical foundation and empirical support for optimizing drying methods.

Dielectric characterisation of chitosan-based composite membranes containing fractionated kraft and organosolv lignin

Chitosan-based composite membranes with fractionated kraft and organosolv lignin were prepared by solvent casting. A small lignin fraction (1%) was added to the neat chitosan to obtain a good distribution. The influence of lignin extraction with ethyl acetate and consequently ethanol on the dielectric and conductive properties of the composites was investigated by dielectric thermal analysis (DETA). Overall, the chitosan-lignin composites exhibit three relaxation mechanisms (β, βwet, and α) and two conductivity phenomena (σ and MWS). FTIR analysis showed that the composites with organosolv lignin fractions have fewer hydroxyl groups than those with kraft lignin, which decreases slightly further for both after ethanol extraction. The lignin fractions with lower molecular weight and higher OH content show stronger interactions with chitosan, due to hydrogen bonding. These interactions affect the thermal activation and cooperativity of the β-, βwet, and α-relaxation. Furthermore, the kraft lignin fractions with many polar groups are very compatible with the chitosan matrix, resulting in a more compact structure and higher fragility. The membranes CS OLEA and CS KLE have a lower electron conductivity and a higher proton conductivity. Thus, they have promising conductivity properties for fuel cell applications.

Effect of –OH on the thermal enhancement properties of NIR-II lanthanide-doped nanoparticles in water

The –OH group plays a key role in the thermal enhancement effect of nanoparticles (NPs). By separately introducing LiCl and D2O into aqueous solutions, we demonstrated how the blue shift and –OH content affect the thermal enhancement factor of NPs.

Study on residual OH content in low-temperature Si oxide films after in situ post-deposition heating (PDH)

We investigated the post-deposition heating (PDH) effect on OH content in SiOx films deposited by atmospheric-pressure CVD using a deposition source of silicone oil (SO) with O3 and TCE vapor at a temperature T d of 180 °C–250 °C. The PDH is performed in situ for 5 min in the deposition chamber just after film deposition without any supply of SO, where the heating temperature is the same as T d. The OH content in the films deposited normally decreases with increasing T d. In contrast, those with PDH decrease with deceasing T d from 220 °C, and, at T d = 190 °C, a minimum OH content can be obtained. This means that lower OH content remains at a lower deposition temperature. The PDH effect on OH reduction can be explained by easily reconstructible structure of SiOx films deposited at low temperature. Furthermore, we discuss the mechanism of the PDH effect from other points of view.

Elucidating tetracycline degradation in a coupled system of photocatalysis combined with Bacillus cereus

Tetracycline (TC) causes environmental problems, so its effective degradation technology has attracted wide attention. A coupled system combined photocatalysis with Bacillus cereus (CS) was adopted for TC degradation in this study to make up the defects of the separate photocatalytic system (SPS) and the separate microbial system (SMS). The results showed that the CS outperformed the SPS or SMS, with the removal rate of TC and total organic carbon (TOC) reaching 82.1 % and 51.6 %, respectively. Moreover, photoelectrons in the CS were significantly higher compared with the SPS, and the hydrogen peroxide concentration, O2− and soluble iron content were slightly higher, but OH content was lower, indicating that photoelectrons played a primary role in TC degradation. The CS had stronger electron transport activity compared with the SMS, indicating that the presence of photocatalyst was conducive to the degradation of TC by Bacillus cereus. The lower cytochrome C content in the CS revealed that photocatalysis caused a certain degree of damage to Bacillus cereus, but it still could hinder the recombination of photoelectrons and holes, which enhanced the degradation efficiency. Finally, the degradation pathway of TC was inferred by intermediate products, and the result indicated TC was effectively degraded under the combined action of photocatalysis and microorganisms. The study provides valuable insights for degradation of antibiotics.

Micro-ridge-furrow soil moisture regulation technology improves seedling quality and yield of winter rapeseed

Rapeseed (Brassica napus L.) is an important oil crop worldwide, and the Yangtze River Basin (YRB) region is one of the most vital rapeseeds producing areas in China. However, the uneven distribution of annual precipitation during the rapeseed seedling stage in this region often leads to droughts and waterlogging, resulting in declined rapeseed seedling quality and yield. Therefore, this study aimed to assess the impact of micro-ridge-furrow planting (MR) and conventional flat cropping planting (FC) under straw returning on rapeseed seedling growth and yield during two growing seasons: wet year (WY) and dry year (DY). In MR planting, rapeseed was sown either on the ridge surface (RS) or in the ridge furrow (RF). We found that MR planting had stronger regulation of soil temperature and humidity compared to FC. The average soil volume water content in RS was 19.2 % lower than FC, while in RF, it was 9.0 % higher than FC. Under MR planting, the daily temperature fluctuations in RF were smaller than in FC, whereas in RS, they were larger than in FC. Through the adjustment of temperature and humidity, MR increased the activities of β-glucosidase (β-Glu) and cellulose disaccharide hydrolase (CBH) in the soil, thereby accelerating rice straw decomposition. Importantly, MR led to improved root growth, seedling quality, precipitation water use efficiency (WUEP), and yield of rapeseed during both the WY and DY seasons. Notably, root morphological traits were significantly altered under straw returning (RT) in MR, particularly with an 11.0 % increase in root surface area, which showed a significant correlation with the indoleacetic acid and jasmonic acid contents in the root system. Furthermore, RT increased antioxidant enzymes activity in rapeseed roots. The H2O2 and ∙OH contents in MR were lower than in FC, indicating that the roots of MR were capable of self-protection and reducing the accumulation of superoxide radicals and peroxides by adapting actively to the soil water environment under straw returning. The yield and WUEP of MR were higher by 11.9 % and 21.0 %, respectively, compared to FC. In conclusion, MR planting has the potential to enhance seedling quality and increase rapeseed yield when combined with rice straw returning. This finding provides technical support for realizing the full and strong seedling establishment and improving the cultivation of direct-seeded rapeseed in the YRB region.