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Summary: Activity‐based sensing probes are powerful tools for monitoring enzymatic activities in complex biological samples such as cellular and live animals; however, their application in plants remains challenging.Herein, fourteen activity‐based fluorescent probes were assayed against Arabidopsis O‐methyltransferases (AtOMTs). One probe, 3‐BTD, displayed a high selectivity, reactivity, and fluorescence response toward AtOMTs especially the isoform AtCCoAOMT. We further characterized the features of this probe and explored whether it could be used to detect OMT activities in living plant cells.Our results show that 3‐BTD can be used to visualize OMT activity in Arabidopsis, and no fluorescent signal was observed in the comt/ccoaomt double mutant, indicating that it has good specificity. Interestingly, in contrast to the observation that AtCCoAOMT‐YFP accumulated in both cytoplasm and nucleus, OMT enzymatic activity tracked by 3‐BTD probe was found only in the cytoplasm. This underscores the importance of activity‐based sensing in studying protein function. Moreover, 3‐BTD can be successfully applied in OMT visualization of different plants.This study indicates that 3‐BTD can serve as a potential probe for in situ monitoring the real activity of OMT in multiple plants and provides a strategy for visualizing the activity of other enzymes in plants. [ABSTRACT FROM AUTHOR]

The effect of various states of Fe(Fe,FeO,and Fe2O3) on the reduction of Cr2O3 was investigated by conducting isothermal experiments on the reduction of Fe-Cr2O3,Fe2O3-Cr2O3 and FeCr2O4 by graphite at 1350-1550℃ combined with X-ray diffraction and scanning electron microscopy with energy-dispersive spectrometry. It is shown that the tendency of final reduction degree is Fe2O3-Cr2O3-C 〉 FeCr2O4-C 〉 Fe-Cr2O3-C at each temperature,and the transformation path of the three samples is oxides → carbides → Fe-Cr-C alloy. Liquid alloy which earlier emerges and low carbon-content carbides promote the reduction of Fe2O3-Cr2O3. Low carbon dissolution in liquid alloy limits the reduction degree of FeCr2O4. The large amount of carbides and little liquid alloy retard the reduction of Fe-Cr2O3. The apparent activation energies of Fe-Cr2O3-C,FeCr2O4-C and Fe2O3-Cr2O3-C are 142.90,111.84 and 128.9 kJ·mol-1,respectively.

Based on self-healing technology of closed wall microcapsules in goaf, silicon carbide-phenolic resin (SiC-PF) microcapsules were prepared by in-situ polymerization with epoxy resin E-51 as core material and silicon carbide (SiC) doped phenolic resin as wall material. The microstructure and particle size distribution of the microcapsules were characterized by scanning electron microscopy (SEM) and laser particle size analyzer. The structure of the microcapsules was analyzed by Fourier transform infrared spectroscopy (FTIR). The thermal degradation behavior of the microcapsules was tested by thermogravimetric analyzer (TG). The nanoindentation instrument was used to analyze the capsule wall performance of the microcapsules, and the mass loss rate of the microcapsules was tested at room temperature. The results show that with the increase of SiC content, the particle size of SiC-PF microcapsules is uniform, the thermal stability is good, the performance of capsule wall is greatly improved, and the mass loss rate is small. The initial thermal decomposition temperature of 0.8SiC-PF microcapsules is increased to 279 °C, the carbon residue rate is 12.6%, the rupture load of the capsule wall is 95.49 mN, and the mass loss rate is 1.82% after 100 d at room temperature. The addition of SiC improves the particle shape, thermal stability, capsule wall characteristics and storage stability of PF microcapsules. [ABSTRACT FROM AUTHOR]

Reconstructing the development of sporangia in seed-free vascular plants provides crucial information about key processes enabling the production of spores that are important in the life cycle of these plants. By applying fluorescence imaging in intact tissues using dyes and confocal microscopy, this study aimed to reconstruct the key steps during the development of sporangia. Special emphasis was taken on the cell wall structures of tapetum and spore mother cells that have been challenged by microscopical documentation in the past. After staining the cell wall and cytoplasm using calcofluor white and basic fuchsin, the sporangium development of Pteris multifida was observed using confocal microscopy. The clear cell lineages from the sporangial initial cell to stalk, epidermis, inner tapetum, outer tapetum, and sporogenous cells were revealed by confocal imaging. The sporangium development improved in this work will be useful for a general understanding of fern spore formation. [ABSTRACT FROM AUTHOR]

Photoperiod/temperature‐sensitive genic male sterility (P/TGMS) is widely applied for improving crop production. Previous investigations using the reversible male sterile (rvms) mutant showed that slow development is a general mechanism for restoring fertility to P/TGMS lines in Arabidopsis. In this work, we isolated a restorer of rvms–2 (res3), as the male sterility of rvms–2 was rescued by res3. Phenotype analysis and molecular cloning show that a point mutation in UPEX1 l in res3 leads to delayed secretion of callase A6 from the tapetum to the locule and tetrad callose wall degradation. Electrophoretic mobility shift assay and chromatin immunoprecipitation analysis demonstrated that the tapetal transcription factor ABORTED MICROSPORES directly regulates UPEX1 expression, revealing a pathway for tapetum secretory function. Early degradation of the callose wall in the transgenic line eliminated the fertility restoration effect of res3. The fertility of multiple known P/TGMS lines with pollen wall defects was also restored by res3. We propose that the remnant callose wall may broadly compensate for the pollen wall defects of P/TGMS lines by providing protection for pollen formation. A cellular mechanism is proposed to explain how slow development restores the fertility of P/TGMS lines in Arabidopsis. [ABSTRACT FROM AUTHOR]

The middle layer is an essential cell layer of the anther wall located between the endothecium and tapetum in Arabidopsis. Based on sectioning, the middle layer was found to be degraded at stage 7, which led to the separation of the tapetum from the anther wall. Here, we established techniques for live imaging of the anther. We created a marker line with fluorescent proteins expressed in all anther layers to study anther development. Several staining methods were used in the intact anthers to study anther cell morphology. We clarified the initiation, development, and degradation of the middle layer in Arabidopsis. This layer is initiated from both the inner and outer secondary parietal cells at stage 4, stopped cell division at stage 6, and finally degraded at stage 11. The neighboring cell layers, the epidermis, and endothecium continued cell division until stage 10, which led to a thin middle layer. The degradation of the tapetum cell wall at stage 7 lead to its isolation from the anther wall. This work presents fundamental information on the development of the middle layer, which facilitates the further investigation of anther development and plant fertility. These live imaging methods could be useful in future studies. [ABSTRACT FROM AUTHOR]

1,1-diamino-2,2-dinitroethene (FOX-7) is a novel explosive with low sensitivity and high performance. The compatibility of FOX-7 with nine common energetic materials including hexanitrohexazaisowurtzitane (CL-20), cyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine (RDX), 3,4-dinitrofurazanfuroxan (DNTF), 3-nitro-1,2,4-triazol-5-one (NTO), hexanitrostilbene (HNS-II), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), 2,4,6-triamino-1,3,5-trinitrobenzene (TATB), and 2,4,6-trinitrotoluene (TNT) were tested by differential scanning calorimetry (DSC) and the vacuum stability test (VST) as the thermal technique and X-ray diffractometry (XRD) as a nonthermal technique. DSC measurements showed that the binary systems of FOX-7/CL-20, FOX-7/HMX, FOX-7/NTO, and FOX-7/TNT were compatible in grade of A, the systems of FOX-7 with heat-resistant explosives including HNS-II, LLM-105, and TATB were compatible as well in grade of A-B, and the binary systems of FOX-7/DNTF and FOX-7/RDX had poor compatibility. VST results indicated that FOX-7 was compatible with nine energetic materials. Besides, the compatibility results of the thermal analysis were confirmed by the XRD technique. [ABSTRACT FROM AUTHOR]

The submicron-RDX with spherical shape and uniform particle size distribution was successfully prepared by green mechanical demulsification technology. The morphology, particle size distribution, thermal properties and safety performance were characterized. The particle size distribution characteristics of submicron-sized RDX prepared were explored based on the fractal geometry theory, which compared with the conventional recrystallization method. The results show that the RDX fabricated via the green mechanical demulsification technology is spherical shape with a median diameter of 470 nm, and possesses better thermal stability and safety than that of RDX refined by the traditional recrystallization. In the double logarithm coordinates, the weight cumulative percentage of RDX prepared using green mechanical demulsification technology and recrystallization has a linear relationship with the particle size, and the fractal dimension D of the particles are 1.544 73 and 0.829 96, respectively, revealing that the submicron-sized RDX particles prepared by the former has a narrower particle size distribution, and better dispersion. [ABSTRACT FROM AUTHOR]