Phase Separation of Mixed Micelles and Synthesis of Hierarchical Porous Materials

The mixed micelle template approach is one of the most promising synthesis methods for hierarchical porous materials. Although considerable research efforts have been made to explore the formation mechanism, explicit theoretical guidance for appropriately choosing templates is still not available. We found that the phase separation occurring in the mixed micelles would be the key point for the synthesis of hierarchical porous materials. Herein, the pseudophase separation theory for the critical micelle concentration (cmc) combined with the Flory–Huggins theory for the chain molecular mixture were employed to investigate the properties of mixed surfactant aqueous solutions. The cmc values of mixed surfactant solutions were experimentally determined to calculate the Flory–Huggins interaction parameter between two surfactants, χ. When χ is larger than the critical value, χ_c, the phase separation would occur within the micellar phase, resulting in two types of mixed micelles with different surfactant compositions, and hence different sizes, which could be used as the dual-template to induce bimodal pores with different pore sizes. Therefore, the Flory–Huggins theory could be a theoretical basis to judge whether the mixed surfactants were the suitable templates for inducing hierarchical porous materials. We chose cetyltrimethylammonium bromide (CTAB) and <i>n</i>-octylamine (OA) as a testing system. The phase separation behavior of the mixed solutions as well as the successful synthesis of hierarchical porous materials by this dual-template indicated the feasibility of preparing hierarchical porous materials based on the concept of phase separation of the mixed micelles

Nitrogen-Doped Coal Tar Pitch Based Microporous Carbons with Superior CO₂ Capture Performance

Coal tar pitch based nitrogen-doped porous carbons were developed by FeCl₃ activation for enhanced CO₂ capture. The carbon materials, synthesized with different FeCl₃/carbon precursor mass ratios and activation temperatures, exhibit high porosity, especially microporosity, and nitrogen species contents, leading to superior CO₂ adsorption capacities in the range of 3.71–4.58 mmol g^–1 and 5.68–7.18 mmol g^–1 at 25 and 0 °C under 1 bar, respectively. In particular, N-AC-600-2 and N-AC-600-3 materials show the highest uptakes of CO₂ at 25 and 0 °C, respectively, which rank among the best porous carbon sorbents. The nitrogen-doping and porosity of the fabricated carbons have combined impact on CO₂ adsorption. In addition, both excellent regenerability and high CO₂/N₂ selectivity were achieved, making these carbon materials promising candidates for large-scale CO₂ adsorption

Nitrogen-Doped Porous Carbon Nanosheets Derived from Coal Tar Pitch as an Efficient Oxygen-Reduction Catalyst

High value-added processing and manufacturing of coal tar pitch (CTP), an abundant and cheap byproduct of the coal industry, is a crucial issue worldwide. Herein, novel nitrogen-doped porous carbon nanosheets (N-PCN) were fabricated by selecting CTP and ferric chloride (FeCl₃) as the carbonaceous source and mild activating agent, respectively. Due to the synergistic effects of the unique flaky graphitic structure, hierarchical porosity, high nitrogen-doping contents, and trace of Fe-containing sites, N-PCN exhibited excellent oxygen-reduction (ORR) electrocatalytic activity in alkaline medium. Linear sweep voltammetry (LSV) testing results for N-PCN showed that the diffusion-limited current density was as high as 5.8 mA cm^–2 and the half-wave potential was 0.85 V (vs RHE), both better than commercial 20 wt % Pt/C. Moreover, N-PCN showed an ideal methanol tolerance and catalytic stability, indicating its potential application as cathode catalysts in direct methanol fuel cells (DMFCs)

Proteome Profile of Starch Granules Purified from Rice (<i>Oryza sativa</i>) Endosperm

<div><p>Starch is the most important food energy source in cereals. Many of the known enzymes involved in starch biosynthesis are partially or entirely granule-associated in the endosperm. Studying the proteome of rice starch granules is critical for us to further understand the mechanisms underlying starch biosynthesis and packaging of starch granules in rice amyloplasts, consequently for the improvement of rice grain quality. In this article, we developed a protocol to purify starch granules from mature rice endosperm and verified the quality of purified starch granules by microscopy observations, I₂ staining, and Western blot analyses. In addition, we found the phenol extraction method was superior to Tris-HCl buffer extraction method with respect to the efficiency in recovery of starch granule associated proteins. LC-MS/MS analysis showed identification of already known starch granule associated proteins with high confidence. Several proteins reported to be involved in starch synthesis in prior genetic studies in plants were also shown to be enriched with starch granules, either directly or indirectly, in our studies. In addition, our results suggested that a few additional candidate proteins may also be involved in starch synthesis. Furthermore, our results indicated that some starch synthesis pathway proteins are subject to protein acetylation modification. GO analysis and KEGG pathway enrichment analysis showed that the identified proteins were mainly located in plastids and involved in carbohydrate metabolism. This study substantially advances the understanding of the starch granule associated proteome in rice and post translational regulation of some starch granule associated proteins.</p></div

KEGG pathways enriched in the starch granule proteome.

<p>KEGG pathway enrichment analysis of starch granule proteome. The value of -log10 (Fisher's test p value) is shown.</p

Work flow diagram showing the steps of the starch granule purification.

<p>Mature rice endosperm were used as the starting materials for this experiment. The final products were the purified starch granules used for further experiments in this report.</p

GO Distribution of the Starch Granule Proteins.

<p>GO Distribution of the Starch Granule Proteins.</p

Distribution of identified proteins based on their peptide counts.

<p>A: Protein peptide count numbers vs numbers of proteins. The proteins identified with the same peptide counts were grouped together to obtain the protein numbers. X-axis: protein peptide counts; Y-axis: number of proteins. B: Peptide count percentage distribution of 40 proteins with highest peptide counts (excluding storage proteins) in the chloroplast/amyloplast (red) and other organelles (blue).</p

Image of purified starch granules and the intermediate products of purification.

<p>A: I₂ stain image of the purified starch granules. Microscope observation with 40 × amplification; B: Cross section image of rice endosperm viewed by SEM. 6k amplification; C: Large endosperm fragment image under SEM. 6k amplification; D: Endosperm fragment image under SEM. 6k amplification; E: Partially purified starch granule image under SEM, 6k amplification; F: The sediments of grounded endosperm image under SEM, 6k amplification; G-I: Purified starch granule image at different magnifications under SEM. G: 1 k amplification; H: 6k amplification; I: 24 k amplification.</p

Proteins enriched in starch and sucrose metabolic pathways.

<p>The enzymes marked with yellow and blue color are proteins enriched in rice starch granule proteome.</p