In Situ MOF-74-Pyrolysis-Generated Porous Carbon Supporting Spinel Cu0.15Co2.85O4/C Boosts Ammonium Perchlorate Accelerating Decomposition: Precise Cu Doping Modulating Oxygen Vacancy Concentration

As one of the main components of solid propellant, ammonium perchlorate (AP) shows slow sluggish decomposition kinetics with unconcentrated heat release. To achieve efficient catalytical decomposition, it is a significant challenge to design reasonable catalyst structure and explore the interaction between catalyst and AP. Herein, a series of porous carbon supported spinel-typed homogeneous heterometallic composites CuxCo3-xO4/C via pyrolysis of MOF-74-Co doped Cu. On basis of precise electronic-structure-tuning through modulating Cu/Co ratio in MOF-74, Cu0.15Co2.85O4/C with 5% Cu-doping featuring oxygen vacancy concentration of 26.25% exhibits the decrease to 261.5 °C with heat release up to 1222.1 J g-1 (456.9 °C and 669.2 J g-1 for pure AP). The detail process of AP accelerated decomposition is approved by TG-DSC-FTIR-MS technique. Density functional theory calculation revealed that in the Cu0.15Co2.85O4/C, the distinctive ability for NH3 catalyzed oxidation assisted with absorption performance of active porous C boosts accelerating AP decomposition. The findings would provide an insight for perceiving and understanding AP catalytic decomposition.

Interlayer Entropy Engineering Inducing the Symmetry-Broken Layered Oxide Cathodes to Activate Reversible High-Voltage Redox Reaction

The as-reported doping entropy engineering of electrode materials that are usually realized by the sharing of multiple metal elements with the metal element from the lattice body, potentially has three shortages of stringent synthesis conditions, large active element loss, and serious lattice distortion. Herein, an interlayer entropy engineering of layered oxide cathodes is proposed, where the multiple metal ions are simultaneously intercalated into the same interlayer sites, thus avoiding the three shortages. Concretely, a novel interlayer medium-entropy V2O5 ((MnCoNiMgZn)0.26V2O5∙0.84H2O) is successfully constructed by a one-step hydrothermal method. The interlayer medium-entropy effect is revealed to be that five metal ions pre-intercalation induces the local symmetry-broken [VO6] octahedra in bilayer V2O5, thus activating the reversible high-voltage redox reaction, inhibiting the layer slip and following phase transformation by its pinning effect, and enhancing the charge transfer kinetics. As a result, the medium-entropy cathode realizes the trade-off between specific capacity and structural stability with a discharge capacity of 152 mAh g-1 at 0.1 A g-1 after 100 cycles, and a capacity retention rate of 98.7% at 0.5 A g-1 after 150 cycles for Li+ storage. This engineering provides a new guideline for the rational design of high-performance layered oxide cathodes.

Co-regulation of Thermosensor Pathogenic Factors by C-di-GMP-Related Two-Component Systems and a cAMP Receptor-like Protein (Clp) in Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is a major threat to the food industry and human health owing to its strong protease production and biofilm formation abilities. However, information regarding regulatory factors or potential mechanisms is limited. Herein, we observed that temperature differentially regulates biofilm formation and protease production, and a cAMP receptor-like protein (Clp) negatively regulates thermosensor biofilm formation, in contrast to protease synthesis. Among four c-di-GMP-related two-component systems (TCSs), promoter fusion analysis revealed that clp transcription levels were predominantly controlled by LotS/LotR, partially controlled by both RpfC/RpfG and a novel TCS Sm0738/Sm0737, with no obvious effect caused by Sm1912/Sm1911. Biofilm formation in Δclp and ΔTCSs strains suggested that LotS/LotR controlled biofilm formation in a Clp-mediated manner, whereas both RpfC/RpfG and Sm0738/Sm0737 may occur in a distinct pathway. Furthermore, enzymatic activity analysis combined with c-di-GMP level indicated that the enzymatic activity of c-di-GMP-related metabolism proteins may not be a vital contributor to changes in c-di-GMP level, thus influencing physiological functions. Our findings elucidate that the regulatory pathway of c-di-GMP-related TCSs and Clp in controlling spoilage or the formation of potentially pathogenic factors in Stenotrophomonas expand the understanding of c-di-GMP metabolism and provide clues to control risk factors of S. maltophilia in food safety.

SerpinA3N Regulates the Secretory Phenotype of Mouse Senescent Astrocytes Contributing to Neurodegeneration

Senescent astrocyte accumulation in the brain during normal aging is a driver of age-related neurodegenerative diseases such as Alzheimer's disease. However, the molecular events underlying astrocyte senescence in Alzheimer's disease are not fully understood. In this study, we demonstrated that senescent astrocytes display a secretory phenotype known as the senescence-associated secretory phenotype (SASP), which is associated with the upregulation of various proinflammatory factors and the downregulation of neurotrophic growth factors (eg, NGF and BDNF), resulting in a decrease in astrocyte-mediated neuroprotection and increased risk of neurodegeneration. We found that SerpinA3N is upregulated in senescent primary mouse astrocytes after serial passaging in vitro or by H2O2 treatment. Further exploration of the underlying mechanism revealed that SerpinA3N deficiency protects against senescent astrocyte-induced neurodegeneration by suppressing SASP-related factors and inducing neurotrophic growth factors. Brain tissues from Alzheimer's disease model mice possessed increased numbers of senescent astrocytes. Moreover, senescent astrocytes exhibited upregulated SerpinA3N expression in vitro and in vivo, confirming that our cell model recapitulated the in vivo pathology of these neurodegenerative diseases. Altogether, our study reveals a novel molecular strategy to regulate the secretory phenotype of senescent astrocytes and implies that SerpinA3N and its regulatory mechanisms may be potential targets for delaying brain aging and aging-related neurodegenerative diseases.

invMap: a sensitive mapping tool for long noisy reads with inversion structural variants

MOTIVATION

Longer reads produced by PacBio or Oxford Nanopore sequencers could more frequently span the breakpoints of structural variations (SVs) than shorter reads. Therefore, existing long-read mapping methods often generate wrong alignments and variant calls. Compared to deletions and insertions, inversion events are more difficult to be detected since the anchors in inversion regions are nonlinear to those in SV-free regions. To address this issue, this study presents a novel long-read mapping algorithm (named as invMap).

RESULTS

For each long noisy read, invMap first locates the aligned region with a specifically designed scoring method for chaining, then checks the remaining anchors in the aligned region to discover potential inversions. We benchmark invMap on simulated datasets across different genomes and sequencing coverages, experimental results demonstrate that invMap is more accurate to locate aligned regions and call SVs for inversions than the competing methods. The real human genome sequencing dataset of NA12878 illustrates that invMap can effectively find more candidate variant calls for inversions than the competing methods.

AVAILABILITY AND IMPLEMENTATION

The invMap software is available at https://github.com/zhang134/invMap.git.

Temporal and Spatial Variation Characteristics and Influencing Factors of Bacterial Community in Urban Landscape Lakes

Urban landscape lakes are closely related to human activity, but there are limited studies on their bacterial community characteristics and risks to human health. In this study, four different types of urban landscape lakes in Xi'an were selected, and the bacterial community structures in different seasons were analyzed by Illumina Nova high-throughput sequencing technology. Seasonal variations in bacterial communities were analyzed by linear discriminant analysis, STAMP difference analysis, and nonmetric multidimensional scaling. Redundancy analysis was used to investigate the influencing factors. Furthermore, the metabolic functions of bacterial communities were predicted by Tax4Fun. There were clear seasonal differences in the α-diversity of bacteria, with bacterial diversity being higher in winter than in summer in the four urban landscape lakes, and the diversity of different water sources was different; the distributions of Proteobacteria, Actinobacteria, Chloroflexi, and Verrucomicrobia had significant seasonal differences; and the dominant bacteria at the genus level had obvious temporal and spatial differences. Furthermore, a variety of environmental factors had an impact on bacterial communities, and temperature, DO, and nitrogen were the primary factors affecting the seasonal variation in bacteria. There are also significant seasonal differences in the metabolic functions of bacterial communities. These results are helpful for understanding the current status of bacteria in the aquatic environments of such urban landscape lakes.

Improvement in the performance of focusing plasma desorption ionization by altering its counter electrode

RATIONALE

Plasma-based ionization sources play a vital role in rapidly analyzing diverse compounds without extensive sample pretreatment. In contrast to other sources, DC voltage-based ionizations are more advantageous due to their high analytical sensitivity and good tandem with commercially available mass spectrometers without extra power supplies. However, their performance is at the risk of high current DC voltage and helium flow rate, which poses significant challenges to practical operation and increased expense.

METHODS

In this work, we propose a novel focusing plasma desorption ionization (FPDI) in which a visible plasma beam is favorably generated between a conducting wire in a polymeric tube and a counter electrode composed of metal mesh and filter paper drilled with holes. A systematic investigation has been conducted on the influences of the geometry of drilled holes in filter paper, applied DC voltage, helium flow rate, and filter paper size. The optimized system is used to analyze various pesticides in fluid foodstuffs.

RESULTS

Compared to metal mesh and conducting paper as the counter electrode for FPDI-MS, combining metal mesh and filter paper drilled holes improved the analysis sensitivity by a factor of more than five. By applying the developed protocol for determining pesticides in complex matrixes such as orange juice and milk, a limit of detection as low as 1.3-3.0 ng mL-1 could be achieved.

CONCLUSIONS

A novel FPDI-MS technique has been developed by combining metal mesh and filter paper drilled with holes as the counter electrode and sample carrier. The corresponding improvement in analysis sensitivity facilitates the future expansion of FPDI-MS applications into different pesticides and other compounds in complex matrixes.

Self-Adaptive Electronic Structure of Amphoteric Conjugated Ligand-Modified 3 d Metal-C3 N4 Smart Electrocatalyst by pH Self-Response Realizing Electrocatalytic Self-Adjustment

Constructing pH-responsive smart material provides a new opportunity to address the problem that traditional electrocatalysts cannot achieve both alkaline oxygen evolution reaction (OER) and acidic hydrogen evolution reaction (HER) activities. In this study, amphoteric conjugated ligand (2-aminoterephthalic acid, BDC-NH₂ )-modified 3d metal-anchored graphitic carbon nitride (3d metal-C₃ N₄ ) smart electrocatalysts are constructed, and self-adaptation of the electronic structure is realized by self-response to pH stimulation, which results in self-adjustment of alkaline OER and acidic HER. Specifically, the amino and carboxyl functional groups in BDC-NH₂ undergo protonation and deprotonation respectively under different pH stimulation to adapt to environmental changes. Through DFT calculations, the increase or decrease of electron delocalization range brought by the self-response characteristic is found to lead to redistribution of the Bader charge around the modified active sites. The OER and HER activities are greatly promoted roughly 4.8 and 8.5 times over Co-C₃ N₄ after BDC-NH₂ -induced self-adaptive processes under different environments, arising from the reduced energy barrier of O* to OOH* and ΔG_H* . Impressively, the proposed BDC-NH₂ -induced smart regulation strategy is applicable to a series of 3d metal anchors for C₃ N₄ , including Co, Ni and Fe, providing a general structural upgrading method for constructing smart electrocatalytic systems.

Controlled direct synthesis of single- to multiple-layer MWW zeolite

The minimized diffusion limitation and completely exposed strong acid sites of the ultrathin zeolites make it an industrially important catalyst especially for converting bulky molecules. However, the structure-controlled and large-scale synthesis of the material is still a challenge. In this work, the direct synthesis of the single-layer MWW zeolite was demonstrated by using hexamethyleneimine and amphiphilic organosilane as structure-directing agents. Characterization results confirmed the formation of the single-layer MWW zeolite with high crystallinity and excellent thermal/hydrothermal stability. The formation mechanism was rigorously revealed as the balanced rates between the nucleation/growth of the MWW nanocrystals and the incorporation of the organosilane into the MWW unit cell, which is further supported by the formation of MWW nanosheets with tunable thickness via simply changing synthesis conditions. The commercially available reagents, well-controlled structure and the high catalytic stability for the alkylation of benzene with 1-dodecene make it an industrially important catalyst.