Highly Selective Separation of CO₂, CH₄, and C₂–C₄ Hydrocarbons in Ultramicroporous Semicycloaliphatic Polyimides

Ultramicroporous semicycloaliphatic polyimides with major pore sizes less than 0.5 nm are synthesized through imidization reaction between different aromatic tetraamines and cycloaliphatic dianhydrides. The synergistic role of abundant CO₂-philic imide rings and the molecular sieving effect of ultrasmall pores in the polyimide network bring about high adsorption selectivity of CO₂/CH₄ (37.2) and CO₂/N₂ (136.7). In addition, it is interesting to observe that, under ambient condition (298 K/1 bar), <i>n</i>-butane exhibits the highest uptake (3.15 mmol/g) among the C₁–C₄ alkanes, and the adsorbed amount significantly drops with the reduction of the number of carbon atoms. As a result, the mixed light alkanes can be effectively separated according to the carbon numbers. The separation factors of <i>n</i>-butane/propane and propane/ethane reach 3.1 and 6.5, whereas those of <i>n</i>-butane, propane, and ethane over methane are as high as 414.5, 217.4, and 19.6, respectively. Moreover, the polyimides display large adsorption capacities for 1,3-butadiene (4.64 mmol/g) and propene (2.68 mmol/g) with good selectivity over 1-butene and propane of 3.2 and 3.0, respectively. Together with the excellent thermal and physicochemical stabilities, the ultramicroporous polyimides obtained in this work show promising applications in adsorption/separation for CO₂, CH₄, and C₂–C₄ hydrocarbons

Facile Synthesis of Fluorinated Microporous Polyaminals for Adsorption of Carbon Dioxide and Selectivities over Nitrogen and Methane

Monoaldehyde compounds, benzaldehyde, 4-methyl­benzaldehyde, 4-fluoro­benzaldehyde, and 4-trifluoro­methyl­benzaldehyde, were utilized to react with melamine respectively to yield four hyper-cross-linked microporous polyaminal networks, PAN-P, PAN-MP, PAN-FP, and PAN-FMP, via a facile “one-step” polycondensation without adding any catalyst. It is found that relative to non-fluorinated polymers the fluorinated ones show the increased BET specific surface areas from 615 to 907 m² g^–1. Moreover, the incorporations of methyl and trifluoromethyl on the phenyl rings can effectively tailor the pore sizes from 0.9 to 0.6 nm. The polar C–F bond and nitrogen-rich polyaminal skeleton result in high CO₂ adsorption enthalpies (38.7 kJ mol^–1) and thereby raise the CO₂ uptake up to 14.6 wt % (273 K, 1 bar) as well as large CO₂/N₂ and CO₂/CH₄ selectivities of 78.1 and 13.4 by the ideal adsorbed solution theory, respectively. The facile and scalable preparation method, low cost, and large CO₂ adsorption and selectivities over N₂ and CH₄ endow the resultant microporous polyaminals with promising applications in CO₂-capture from flue gas and natural gas

Ultramicroporous Carbons Derived from Semi-Cycloaliphatic Polyimide with Outstanding Adsorption Properties for H₂, CO₂, and Organic Vapors

Ultramicroporous carbons (UMC-<i>T</i>s) have been successfully prepared using nitrogen- and oxygen-rich porous semicycloaliphatic polyimide as a precursor in the presence of KOH at different carbonization temperatures of 600, 700, and 800 °C, respectively. The evolution of porous and chemical structures of the resultant carbons in the course of carbonization as well as their effects on adsorption of H₂, CO₂, benzene, and cyclohexane are studied in detail. Compared with the porous polyimide precursor, after carbonization treatment, the products exhibit the significantly increased BET specific surface areas from 900 to 2406 m² g^–1 and create large amounts of ultramicropores with the pore size smaller than 0.5 nm, leading to outstanding adsorption capacities for CO₂ (34.0 wt %, 273 K/1 bar) and H₂ (3.7 wt %, 77 K/1 bar). Moreover, it is interesting to observe that UMC-<i>T</i>s possess extraordinarily large uptake for benzene (74.4 wt %, 298 K) and cyclohexane (64.8 wt %, 298 K) at the very low relative pressure (<i>P</i>/<i>P</i>₀ = 0.1), showing promising applications in CO₂ capture, H₂ storage, and removal of toxic organic vapors

Investigation on Pyrolysis of Low Lipid Microalgae Chlorella vulgaris and Dunaliella salina

Chlorella vulgaris and Dunaliella salina are two kinds of microalgae, which are widely distributed in China. Thermal decomposition of low-lipid C. vulgaris and D. salina were performed using thermogravimetric analysis. The effect of heating rates on pyrolytic characteristics was investigated, and thermal decomposition kinetics was determined as well. Furthermore, pyrolysis experiments were carried out on a fixed-bed reactor. The gas, char, and tar yields were analyzed, and the mass balance was from 88.4 to 96.8%. C. vulgaris had higher H₂ yields and lower CH₄ yields than D. salina during pyrolysis. The theoretical calorific value of the pyrolytic gas of D. salina was higher than that of C. vulgaris because D. salina had a higher amount of high heating value components, such as C₂H₆, C₂H₄, and C₂H₂. The biochar from microalgae had a smaller Brunauer–Emmett–Teller surface area than the char from pyrolysis of lignocellulosic biomass. Highest yields of pyrolytic oil were 49.2 and 55.4% (water-free basis) for C. vulgaris and D. salina at 500 °C, respectively. The characteristics of bio-oil from microalgae pyrolysis, including water content, density, acidity, and heating value, were investigated as well as the chemical composition at different pyrolysis temperatures. The microalgae pyrolytic oil was found to have significant levels of alkanes, alkenes, alkines, and esters and be particularly high in nitrogenous compounds. In comparison to the bio-oils from common lignocellulosic biomass, the microalgae oil had lower oxygen and water contents, a lower total acid number, and a higher heating value

Synthesis of Fluorescent Micro- and Mesoporous Polyaminals for Detection of Toxic Pesticides

This paper presents the first report on employing fluorescent porous organic polymers as sensors for the detection of toxic pesticides. Specifically, fluorescent micro- and mesoporous polyaminals with pendant triphenylamine and dibromotriphenylamine chromophore groups are synthesized, which exhibit BET surface area up to 507 m² g^–1, adjustable pore sizes in the range from 0.5 to 36.2 nm and can emit bright turquoise light under the ultraviolet lamp. Using the insecticide (fenitrothion) and herbicides (trifluralin and glyphosate) as analytes, the chemosensing properties are investigated by correlating the porosity parameters and chemical structure of the polymers with the molecular sizes and the energy in the lowest unoccupied molecular orbital of pesticides. Moreover, the effects of different acid–base conditions and solvents including ethanol, water, chloroform, tetrahydrofuran, and <i>N</i>,<i>N</i>-dimethyl­formamide on the chemosensing sensitivity of the polymers are also studied in detail. Particularly, the chemosensing test paper fabricated with the fluorescent polymer rapidly becomes dark upon contacting the pesticide solutions at an extremely low concentration, and the quenching degree is unchanged after repeating the experiments for 10 times, exhibiting the capability of sensible and reusable detection for pesticides

Tetraphenyladamantane-Based Polyaminals for Highly Efficient Captures of CO₂ and Organic Vapors

Tetraphenyladamantane-based polyaminals with ultrasmall pore, large specific surface area and abundant CO₂-philic aminal groups are successfully synthesized, which exhibit simultaneously high CO₂ adsorption capacity of 17.6 wt % (4.0 mmol g^–1, 273 K/1.0 bar) and high adsorption selectivities of CO₂/N₂ (104) and CO₂/CH₄ (24). Especially, at the low pressure, e.g., 0.15 bar, the CO₂ uptake at 273 K can reach 8.7 wt % (1.97 mmol g^–1). The adsorption/selectivity properties are superior to most of microporous organic polymers (MOPs) reported in the literature. Besides the outstanding CO₂-capturing ability, the polymers also possess high uptakes of benzene and cyclohexane vapors up to 72.6 and 52.7 wt %, respectively. In addition, the effects of reaction activity and type of amino groups as well as the size and shape of building blocks on porous architecture of microporous polyaminals are studied. The disclosed results are helpful for the deep understanding of pore formation and interconnecting behavior in MOPs and therefore are of significant importance for the synthetic control of MOPs for a specific application in gas storage and capture of organic vapors

Schisandrin B Attenuates Cancer Invasion and Metastasis Via Inhibiting Epithelial-Mesenchymal Transition

<div><h3>Background</h3><p>Metastasis is the major cause of cancer related death and targeting the process of metastasis has been proposed as a strategy to combat cancer. Therefore, to develop candidate drugs that target the process of metastasis is very important. In the preliminary studies, we found that schisandrin B (Sch B), a naturally-occurring dibenzocyclooctadiene lignan with very low toxicity, could suppress cancer metastasis.</p> <h3>Methodology</h3><p>BALB/c mice were inoculated subcutaneously or injected via tail vein with murine breast cancer 4T1 cells. Mice were divided into Sch B-treated and control groups. The primary tumor growth, local invasion, lung and bone metastasis, and survival time were monitored. Tumor biopsies were examined immuno- and histo-pathologically. The inhibitory activity of Sch B on TGF-β induced epithelial-mesenchymal transition (EMT) of 4T1 and primary human breast cancer cells was assayed.</p> <h3>Principal Findings</h3><p>Sch B significantly suppressed the spontaneous lung and bone metastasis of 4T1 cells inoculated s.c. without significant effect on primary tumor growth and significantly extended the survival time of these mice. Sch B did not inhibit lung metastasis of 4T1 cells that were injected via tail vein. Delayed start of treatment with Sch B in mice with pre-existing tumors did not reduce lung metastasis. These results suggested that Sch B acted at the step of local invasion. Histopathological evidences demonstrated that the primary tumors in Sch B group were significantly less locally invasive than control tumors. In vitro assays demonstrated that Sch B could inhibit TGF-β induced EMT of 4T1 cells and of primary human breast cancer cells.</p> <h3>Conclusions</h3><p>Sch B significantly suppresses the lung and bone metastasis of 4T1 cells via inhibiting EMT, suggesting its potential application in targeting the process of cancer metastasis.</p> </div

Realizing Wide-Temperature Reversible Ca Metal Anodes through a Ca²⁺-Conducting Artificial Layer

Room-temperature Ca deposition/stripping is impeded by the formation of ionic insulating interfaces. Electrolyte optimization could partially enhance Ca reversibility by tailoring the interfaces, but the precise regulation of the composition remains challenging. Herein, we construct an ex situ artificial layer on Ca metal via a facile displacement reaction between metal halides and Ca. These Ca-driven spontaneous layers with precisely controlled interfacial chemistry consist of a Ca metal alloy phase and a calcium halide matrix for conducting Ca2+ and insulating the electrons, as revealed by theoretical and experimental investigations. In particular, the Ca31Sn20/CaBr2 interface enables Ca metal anodes to achieve low polarization and humid air stability over a wide temperature range from −25 to +50 °C. This proof-of-concept work provides an alternative approach to boost Ca2+ diffusivity through customized interfacial chemistry regulation

Sch B inhibits local invasion of 4T1 cells <i>in vivo</i>.

<p>Mice (n = 20 for each group) were treated with Sch B (100 mg/kg body weight) or vehicle intragastrically daily for 7 days. (A) Primary tumors and surrounding tissues were resected on day 15 for hematoxylin-eosin stain (upper, ×40, lower, ×100). (B) immunostaining of E-cadherin and vimentin.(×100).</p

Sch B prolongs mouse survival time in dose-dependent manner.

<p>Mice (n = 8 for each group) receiving Sch B (100, 30, 10 mg/kg body weight) or vehicle every day for total 7 doses, and primary tumors were resected on day 10. (A) Mouse survival time. (B) Mouse body weight. (C) Tumor weight resected on day 10. *, P<0.05, **, P<0.01, Sch B versus control group.</p