Organic Pollutant Clustered in the Plant Cuticular Membranes: Visualizing the Distribution of Phenanthrene in Leaf Cuticle Using Two-Photon Confocal Scanning Laser Microscopy

Plants play a key role in the transport and fate of organic pollutants. Cuticles on plant surfaces represent the first resistance for the uptake of airborne toxicants. In this study, a confocal scanning microscope enhanced with a two-photon laser was applied as a direct and noninvasive probe to explore the in situ uptake of a model pollutant, phenanthrene (PHE), into the cuticular membrane of a hypostomatic plant, <i>Photinia serrulata</i>. On the leaf cuticle surfaces, PHE forms clusters instead of being evenly distributed. The PHE distribution was quantified by the PHE fluorescence intensity. When PHE concentrations in water varying over 5 orders of magnitude were applied to the isolated cuticle, the accumulated PHE level by the cuticle was not vastly different, whether PHE was applied to the outer or inner side of the cuticle. Notably, PHE was found to diffuse via a channel-like pathway into the middle layer of the cuticle matrix, where it was identified to be composed of polymeric lipids. The strong affinity of PHE for polymeric lipids is a major contributor of the fugacity gradient driving the diffusive uptake of PHE in the cuticular membrane. Membrane lipids constitute important domains for hydrophobic interaction with pollutants, determining significant differentials of fugacities within the membrane microsystem. These, under unsteady conditions, contribute to enhance net transport and clustering along the <i>z</i> dimension. Moreover, the liquid-like state of polymeric lipids may promote mobility by enhancing the diffusion rate. The proposed “diffusive uptake and storage” function of polymeric lipids within the membrane characterizes the modality of accumulation of the hydrophobic contaminant at the interface between the plant and the environment. Assessing the capacity of fugacity of these constituents in detail will bring about knowledge of contaminant fate in superior plants with a higher level of accuracy

Aggregation Kinetics and Self-Assembly Mechanisms of Graphene Quantum Dots in Aqueous Solutions: Cooperative Effects of pH and Electrolytes

The cooperative effects of pH and electrolytes on the aggregation of GQDs and the aggregate morphologies are characterized. Because GQDs have an average size of 9 nm with abundant O-functionalized edges, their suspension was very stable even in a high electrolyte concentration and low pH solution. Divalent cations (Mg²⁺ and Ca²⁺) excelled at aggregating the GQD nanoplates, while monovalent cations (Na⁺ and K⁺) did not disturb the stability. For Na⁺ and K⁺, positive linear correlations were observed between the critical coagulation concentration (CCC) and pH levels. For Mg²⁺ and Ca²⁺, negative, but nonlinear, correlations between CCC and pH values could not be explained and predicted by the traditional DLVO theory. Three-step mechanisms are proposed for the first time to elucidate the complex aggregation of GQDs. The first step is the protonation/deprotonation of GQDs under different pH values and the self-assembly of GQDs into GQD-water-GQD. The second step is the self-assembly of small GQD pieces into large plates (graphene oxide-like) induced by the coexisting Ca²⁺ and then conversion into 3D structures via π–π stacking. The third step is the aggregation of the 3D-assembled GQDs into precipitates via the suppression of the electric double layer. The self-assembly of GQDs prior to aggregation was supported by SEM and HRTEM imaging. Understanding of the colloidal behavior of ultrasmall nanoparticles like GQDs is significantly important for the precise prediction of their environmental fate and risk

Enhanced Polarization from Hollow Cube-like ZnSnO₃ Wrapped by Multiwalled Carbon Nanotubes: As a Lightweight and High-Performance Microwave Absorber

Polarization and conduction loss play fundamentally important roles in the nonmagnetic microwave absorption process. In this paper, a uniform and monodisperse hollow ZnSnO₃ cube wrapped by multiwalled carbon nanotubes (ZSO@CNTs) was successfully synthesized via facile hydrothermal treatment. A reasonable mechanism related to Ostwald ripening was proposed to design the varied ZSO@CNTs for the special hollow conductive network. Scanning electron microscopy images clearly indicate that reaction temperature is the key factor for the composite structure, which has a significant effect on its electromagnetic properties. Electron holography proves the inhomogeneous distribution of charge density in the ZSO@CNT system, leading to the occurrence of interface polarization. Complex permittivity properties of ZSO@CNT composites under different reaction temperatures were investigated to optimize the morphology that can distinctly enhance microwave absorption performance. The maximum reflection loss that the ZSO@CNT-130 °C composite can reach is −52.1 dB at 13.5 GHz, and the absorption bandwidths range from 11.9 to 15.8 GHz with a thickness as thin as 1.6 mm. Adjusting the simulation thicknesses from 1 to 5 mm, the efficient absorption bandwidth (RL < −10 dB) that the ZSO@CNT composite could reach was 14.16 GHz (88.8% of 2–18 GHz). The excellent microwave absorption performance may be attributed to the synergistic effects of polarization, conduction loss, and special hollow cage structure. It is proposed that the specially controlled structure could provide an effective path for achieving a high-performance microwave absorber

Nanocellulose Life Cycle Assessment

Nanocellulose is a nascent and promising material with many exceptional properties and a broad spectrum of potential applications. Because of the unique and functional materials that can be created using nanocellulose, pilot-scale development for commercialization has begun. Thus a thorough understanding of its environmental impact, covering the whole life cycle of nanocellulose, becomes the foundation for its long-term sustainable success. In this current study, four comparable lab scale nanocellulose fabrication routes were evaluated through a cradle-to-gate life cycle assessment (LCA) adopting the Eco-Indicator 99 method. The results indicated that, for the chemical–mechanical fabrication routes, the majority of the environmental impact of nanocellulose fabrication is dependent upon both the chemical modification and mechanical treatment route chosen. For sonication, the mechanical treatment overshadows that from the chemical modifications. Adapting the best practice based on unit mass production was 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation followed by homogenization, as TEMPO oxidation resulted in a lower impact than carboxymethylation. Even though the fabrication process of nanocellulose presents a large environmental footprint markup relative to its raw material extraction process (kraft pulping), it still exhibits prominent environmental advantages over other nanomaterials like carbon nanotubes

Enzyme and Chemical Assisted N‑Terminal Blocked Peptides Analysis, ENCHANT, as a Selective Proteomics Approach Complementary to Conventional Shotgun Approach

Shotgun (bottom-up) approach has been widely applied in large-scale proteomics studies. The inherent shortages of shotgun approach lie in that the generated peptides often overwhelm the analytical capacity of current LC–MS/MS systems and that high-abundance proteins often hamper the identification of low-abundance proteins when analyzing complex samples. To reduce the sample complexity and relieve the problems caused by abundant proteins, herein we introduce a modified selective proteomics approach, termed ENCHANT, for enzyme and chemical assisted N-terminal blocked peptides analysis. Modified from our previous Nα-acetylome approach, ENCHANT aims to analyze three kinds of peptides, acetylated protein N-termini, N-terminal glutamine and N-terminal cysteine containing peptides. Application of ENCHANT to HeLa cells allowed to identify 3375 proteins, 19.6% more than that by conventional shotgun approach. More importantly, ENCHANT demonstrated an excellent complementarity to conventional shotgun approach with the overlap of 34.5%. In terms of quantification using data independent acquisition (DIA) technology, ENCHANT quantified 23.9% more proteins than conventional shotgun approach with the overlap of 27.6%. Therefore, our results strongly suggest that ENCHANT is a promising selective proteomics approach, which is complementary to conventional shotgun approach in both qualitative and quantitative proteomics studies. Data are available via ProteomeXchange with identifier PXD007863

Lys-C/Arg-C, a More Specific and Efficient Digestion Approach for Proteomics Studies

Nowadays, bottom-up approaches are predominantly adopted in proteomics studies, which necessitate a proteolysis step prior to MS analysis. Trypsin is often the best protease in choice due to its high specificity and MS-favored proteolytic products. A lot of efforts have been made to develop a superior digestion approach but hardly succeed, especially in large-scale proteomics studies. Herein, we report a new tandem digestion using Lys-C and Arg-C, termed Lys-C/Arg-C, which has been proven to be more specific and efficient than trypsin digestion. Reanalysis of our previous data (<i>Anal. Chem.</i> <b>2018</b>, <i>90</i> (3), 1554–1559) revealed that both Lys-C and Arg-C are trypsin-like proteases and perform better when considered as trypsin. In particular, for Arg-C, the identification capacity is increased to 2.6 times and even comparable with trypsin. The good complementarity, high digestion efficiency, and high specificity of Lys-C and Arg-C prompt the Lys-C/Arg-C digestion. We systematically evaluated Lys-C/Arg-C digestion using qualitative and quantitative proteomics approaches and confirmed its superior performance in digestion specificity, efficiency, and identification capacity to the currently widely used trypsin and Lys-C/trypsin digestions. As a result, we concluded that the Lys-C/Arg-C digestion approach would be the choice of next-generation digestion approach in both qualitative and quantitative proteomics studies. Data are available via ProteomeXchange with identifier PXD009797

Lys-C/Arg-C, a More Specific and Efficient Digestion Approach for Proteomics Studies

Nowadays, bottom-up approaches are predominantly adopted in proteomics studies, which necessitate a proteolysis step prior to MS analysis. Trypsin is often the best protease in choice due to its high specificity and MS-favored proteolytic products. A lot of efforts have been made to develop a superior digestion approach but hardly succeed, especially in large-scale proteomics studies. Herein, we report a new tandem digestion using Lys-C and Arg-C, termed Lys-C/Arg-C, which has been proven to be more specific and efficient than trypsin digestion. Reanalysis of our previous data (<i>Anal. Chem.</i> <b>2018</b>, <i>90</i> (3), 1554–1559) revealed that both Lys-C and Arg-C are trypsin-like proteases and perform better when considered as trypsin. In particular, for Arg-C, the identification capacity is increased to 2.6 times and even comparable with trypsin. The good complementarity, high digestion efficiency, and high specificity of Lys-C and Arg-C prompt the Lys-C/Arg-C digestion. We systematically evaluated Lys-C/Arg-C digestion using qualitative and quantitative proteomics approaches and confirmed its superior performance in digestion specificity, efficiency, and identification capacity to the currently widely used trypsin and Lys-C/trypsin digestions. As a result, we concluded that the Lys-C/Arg-C digestion approach would be the choice of next-generation digestion approach in both qualitative and quantitative proteomics studies. Data are available via ProteomeXchange with identifier PXD009797

“Matryoshka Doll”-Like CeO₂ Microspheres with Hierarchical Structure To Achieve Significantly Enhanced Microwave Absorption Performance

Recently, it is still a great challenge to develop a new type of absorber that possesses special advantages of low cost, ultrawide bandwidth, and strong absorption intensity. Herein, the unique “Matryoshka doll”-like CeO₂ microspheres with tunable interspaces were successfully synthesized by a facile and template-free method. The as-synthesized hierarchical yolk–shell CeO₂ microspheres were constructed by a layer of outer shell and multiple inner cores. The interspace gap of the microspheres can be simply adjusted only by altering the solvothermal reaction time. Simultaneously, Ostwald ripening, Kirkendall effect, and self-etching process contribute a synergetic growth mechanism responsible for this amazing hierarchical architecture. Importantly, the “Matryoshka doll”-like CeO₂ microspheres exhibited significantly strong microwave absorption in the frequency range of 2–18 GHz, with a reflection loss of −71.3 dB at 14.5 GHz and an effective absorption bandwidth of 5.4 GHz (<−10 dB), which is superior to the multicomponent absorbers. Such an outstanding microwave absorption performance stems from the unique hierarchical yolk–shell structure and the designable interspaces, leading to the multiple scattering, interfacial polarization, and plasma dielectric oscillation from the abundant interfaces and curved surfaces, which can be illustrated by the related results from electron holography and electron energy loss spectroscopy. To the best of our knowledge, the “Matryoshka doll”-like CeO₂ microspheres with a facile synthesis process, low cost, and excellent microwave absorption performance are believed to be an optimal candidate of single-component absorbers and helpful in the study of absorption mechanism

Table_2_Traits-Based Integration of Multi-Species Inoculants Facilitates Shifts of Indigenous Soil Bacterial Community.DOCX

<p>Microbial co-inoculation is considered to be an innovative approach and had been applied worldwide. However, the underlying mechanisms of microbial co-inoculants constructions, especially the trait-based combination of distinctly different microbial species remains poorly understood. In this study, we constructed two microbial co-inoculants with the same three strains with emphasis on the microbial, soil and plant traits. Microbial co-inoculants 1 (M1) were constructed according to soil fertility, microbial activity and cucumber nutrient requirement with a 2:1:2 ratio (Ensifer sp. NYM3, Acinetobacter sp. P16 and Flavobacterium sp. KYM3), while microbial co-inoculants 2 (M2) were constructed according to soil fertility and cucumber nutrient requirement with a 1:10:1 ratio without considering the difference in the nutrient supply capability of microbial species. The results showed that M1 and M2 both obviously increased cucumber yields. The M1 had significant highest pH value, total nitrogen (TN) and invertase activity (IA). The M2 had significant highest available phosphate (AP), NO₃-N, urea activity (UA), and alkaline phosphatase activity (APA). Gammaproteobacteria, Acidobacteria, Nitrospirae, and Armatimonadetes were significantly increased, while Actinobacteria and Firmicutes were significantly decreased by microbial co-inoculations (M1 and M2). The bacterial lineages enriched in M1 were Gammaproteobacteria and TM7. Acidobacteria, Bacteroidetes, and Deltaproteobacteria were enriched in M2. Principal coordinate analysis (PCoA) analysis showed that the bacterial communities were strongly separated by the different microbial inoculation treatments. The functional groups of intracellular_parasites were highest in M1. The functional groups of phototrophy, photoautotrophy, nitrification, fermentation, cyanobacteria, oxygenic_photoautotrophy, chitinolysis and animal_parasites_or_symbionts were highest in M2. Based on correlation analysis, it inferred that the M1 and M2 might promote cucumber yields by mediating bacterial community structure and function about nitrogen fixing and urea-N hydrolysis, respectively. Collectively, these results revealed that microbial co-inoculants had positive effects on cucumber yields. Trait-based integration of different microbial species had significant effects on soil properties and bacterial communities. It indicated that microbial activity should be considered in the construction of microbial co-inoculants. This will expand our knowledge in bacteria interaction, deepen understanding of microbial inoculants in improving plant performance, and will guide microbial fertilizer formulation and application in future.</p

Table_1_Traits-Based Integration of Multi-Species Inoculants Facilitates Shifts of Indigenous Soil Bacterial Community.DOCX

<p>Microbial co-inoculation is considered to be an innovative approach and had been applied worldwide. However, the underlying mechanisms of microbial co-inoculants constructions, especially the trait-based combination of distinctly different microbial species remains poorly understood. In this study, we constructed two microbial co-inoculants with the same three strains with emphasis on the microbial, soil and plant traits. Microbial co-inoculants 1 (M1) were constructed according to soil fertility, microbial activity and cucumber nutrient requirement with a 2:1:2 ratio (Ensifer sp. NYM3, Acinetobacter sp. P16 and Flavobacterium sp. KYM3), while microbial co-inoculants 2 (M2) were constructed according to soil fertility and cucumber nutrient requirement with a 1:10:1 ratio without considering the difference in the nutrient supply capability of microbial species. The results showed that M1 and M2 both obviously increased cucumber yields. The M1 had significant highest pH value, total nitrogen (TN) and invertase activity (IA). The M2 had significant highest available phosphate (AP), NO₃-N, urea activity (UA), and alkaline phosphatase activity (APA). Gammaproteobacteria, Acidobacteria, Nitrospirae, and Armatimonadetes were significantly increased, while Actinobacteria and Firmicutes were significantly decreased by microbial co-inoculations (M1 and M2). The bacterial lineages enriched in M1 were Gammaproteobacteria and TM7. Acidobacteria, Bacteroidetes, and Deltaproteobacteria were enriched in M2. Principal coordinate analysis (PCoA) analysis showed that the bacterial communities were strongly separated by the different microbial inoculation treatments. The functional groups of intracellular_parasites were highest in M1. The functional groups of phototrophy, photoautotrophy, nitrification, fermentation, cyanobacteria, oxygenic_photoautotrophy, chitinolysis and animal_parasites_or_symbionts were highest in M2. Based on correlation analysis, it inferred that the M1 and M2 might promote cucumber yields by mediating bacterial community structure and function about nitrogen fixing and urea-N hydrolysis, respectively. Collectively, these results revealed that microbial co-inoculants had positive effects on cucumber yields. Trait-based integration of different microbial species had significant effects on soil properties and bacterial communities. It indicated that microbial activity should be considered in the construction of microbial co-inoculants. This will expand our knowledge in bacteria interaction, deepen understanding of microbial inoculants in improving plant performance, and will guide microbial fertilizer formulation and application in future.</p