Dehydration entropy drives liquid-liquid phase separation by molecular crowding

Liquid-liquid phase separation occurs in cells and can be induced in artificial systems, but the mechanism of the effect of molecular crowders is unclear. Here dehydration entropy-driven phase separation of model charged polymers lacking any chemical complexity or hydrophobicity is shown to be enhanced by polyethylene glycol. Complex coacervation driven liquid-liquid phase separation (LLPS) of biopolymers has been attracting attention as a novel phase in living cells. Studies of LLPS in this context are typically of proteins harboring chemical and structural complexity, leaving unclear which properties are fundamental to complex coacervation versus protein-specific. This study focuses on the role of polyethylene glycol (PEG)-a widely used molecular crowder-in LLPS. Significantly, entropy-driven LLPS is recapitulated with charged polymers lacking hydrophobicity and sequence complexity, and its propensity dramatically enhanced by PEG. Experimental and field-theoretic simulation results are consistent with PEG driving LLPS by dehydration of polymers, and show that PEG exerts its effect without partitioning into the dense coacervate phase. It is then up to biology to impose additional variations of functional significance to the LLPS of biological systems.11Ysciescopu

Oxidative dehydrogenation of ethane to ethylene over LiCl/SO42--ZrO2 catalyst

Sulfated zirconia (SO42--ZrO2) samples were prepared by a modified two-step method (refluxing ZrO(OH)(2) precursor in basic solution followed by drying and (NH4)(2)SO4 impregnation) and then impregnated with a LiCl solution to give the SO42--ZrO2-supported LICI catalysts with Li mass content of 0.5% similar to 15%. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, N-2 adsorption, temperature-programmed desorption-mass spectrometry, and X-ray photoelectron spectroscopy. The results show that with increasing LiCl loading, the specific surface area and acidity of the catalysts as well as the volume fraction of tetragonal zirconia in the catalysts decrease, while the catalytic performance of the catalysts for oxidative dehydrogenation of ethane (ODHE) to ethylene increases. Over the LiCl/SO42--ZrO2 catalyst with a Li content of 15% ethylene yield of 77.8% with an ethane conversion of 90.6% is achieved at 650 degrees C, and the yield higher than 71% is maintained over a period of 24 h. The textural structure of ZrO? has little effect on the catalytic behavior of the LiCl/SO42--ZrO2 catalysts. The specific surface area of SO42--ZrO2 samples prepared by the fled two-step method is much bigger than that of the SO42--ZrO2 samples made by the method reported in literature, and therefore more LiCl call be loaded on unit mass of support. This is favorable to improve the catalyst stability and slow down catalyst deactivation during the ODHE reaction due to the loss of LiCl

The complete chloroplast genome sequence of Artemisia ordosica

The complete chloroplast genome sequence of Artemisia ordosica was characterized from Illumina pair-end sequencing. The chloroplast genome of A. ordosica was 151,209 bp in length, containing a large single-copy region (LSC) of 80,975 bp, a small single-copy region (SSC) of 16,002 bp, and two inverted repeat (IR) regions of 27,116 bp. The overall GC content is 30.71%, while the correponding values of the LSC, SSC, and IR regions are 64.2%, 69.3%, and 60.0%, respectively. The genome contains 138 complete genes, including 91 protein-coding genes (62 protein-coding gene species), 39 tRNA genes (29 tRNA species) and 8 rRNA genes (4 rRNA species). The Neighbour-joining phylogenetic analysis showed that A. ordosica and Artemisia scoparia clustered together as sisters to other Artemisia species

Fabrication of nitrogen-doped graphene decorated with organophosphor and lanthanum towards high-performance polymer nanocomposites

Despite substantial advances, it remains imperative but challenging to develop high-performance polymer/graphene nanocomposites combining with excellent mechanical, thermal, and fire-retardant properties. In this work, a novel kind of graphene-based multifunctional nanofiller (La@PN-RGO) was fabricated via the nitrogen doping and the decoration with organophosphorus and lanthanum based on graphene oxide, which is then incorporated into acrylonitrile−butadiene−styrene (ABS) resin via melt blending to obtain resultant ABS nanocomposites. As expected, the La@PN-RGO nanosheets were well dispersed in ABS composites. Attractively, with only 1.0 wt % of La@PN-RGO incorporated into ABS matrix, the peak heat release rate (PHRR) and total smoke production (TSP) were significantly reduced by 38% and 36%, which is much superior to its counterparts at the same nanofillers loading level. The notably enhanced fire safety was primarily attributed to the rare earth catalysis accompanied by the lamellae blocking effect and intumescent flame retardancy of La@PN-RGO. Additionally, ABS/La@PN-RGO composite exhibited a 16% enhancement in tensile strength without at the expense of extensibility. This effective and promising method may open a new pathway to obtain high-performance polymer/graphene nanocomposites

Realizing simultaneous improvements in mechanical strength, flame retardancy and smoke suppression of ABS nanocomposites from multifunctional graphene

Acrylonitrile-butadiene-styrene (ABS), as one of the most widely used engineering plastics, suffers from the problem of serious flammability and low mechanical strength. To address such an intractable challenge, herein, we report the design of a graphene-based multifunctional additive (Sb-Mo/Br-rGO) via the bromination followed by precipitating antimony molybdenum. The surface functionalization enables Sb-Mo/Br-rGO to homogeneously disperse within the ABS matrix through facile melt-blending. The incorporation of 5 wt% Sb-Mo/Br-rGO leads to a 31% increase in tensile strength and 73% increase in elastic modulus relative to the ABS bulk. In addition to significant enhancement in thermal stability, the inclusion of 5 wt% Sb-Mo/Br-rGO significantly delays the time to ignition of ABS by 12 s, and noticeably reduces the peak heat release rate (PHRR) and total smoke production (TSP) by 45% and 54%, respectively. Such improved performance portfolio is primarily because the mechanical reinforcing and thermal barrier effect of graphene nanosheets, the flame retardant effect of bromine/antimony, and the smoke suppression action of antimony molybdenum. This work provides an innovative methodology for the design of multifunctional additives to create high-performance polymeric materials with high strength and low flammability, thus contributing to improving the quality of life

Functionalizing graphene decorated with phosphorus-nitrogen containing dendrimer for high-performance polymer nanocomposites

In this paper, we demonstrate a novel strategy for fabricating advanced polymer composites based on functionalized graphene oxide decorated with phosphorus-nitrogen-containing dendrimers (PND-GO). Both X-ray diffraction and transmission electron microscopy results show that reduced PND-GO uniformly disperses within polymer matrix and is exfoliated in polyurethane (PU) via in situ polymerization. Cone calorimetry results show that incorporating 2 wt% reduced PND-GO into PU decreases the peak heat release rate by 53% and prolongs the time to ignition by 28 s as compared with the PU bulk. Besides, the tensile strength and Young's modulus are remarkably enhanced by about 2 times and 5 times, respectively

Modification Strategies for Development of 2D Material-Based Electrocatalysts for Alcohol Oxidation Reaction

2D materials, such as graphene, MXenes (metal carbides and nitrides), graphdiyne (GDY), layered double hydroxides, and black phosphorus, are widely used as electrocatalyst supports for alcohol oxidation reactions (AORs) owing to their large surface area and unique 2D charge transport channels. Furthermore, the development of highly efficient electrocatalysts for AORs via tuning the structure of 2D support materials has recently become a hot area. This article provides a critical review on modification strategies to develop 2D material-based electrocatalysts for AOR. First, the principles and influencing factors of electrocatalytic oxidation of alcohols (such as methanol and ethanol) are introduced. Second, surface molecular functionalization, heteroatom doping, and composite hybridization are deeply discussed as the modification strategies to improve 2D material catalyst supports for AORs. Finally, the challenges and perspectives of 2D material-based electrocatalysts for AORs are outlined. This review will promote further efforts in the development of electrocatalysts for AORs

Co-amorphous solid dispersion systems of lacidipine-spironolactone with improved dissolution rate and enhanced physical stability

Co-amorphous solid dispersion (C-ASD) systems have attracted great attention to improve the solubility of poorly soluble drugs, but the selection of an appropriate stabilizer to stabilize amorphous forms is still a huge challenge. Herein, C-ASD system of two clinical combined used drugs (lacidipine (LCDP) and spironolactone (SPL)) as stabilizers to each other, was prepared by solvent evaporation method. The effects of variation in molar ratio of LCDP and SPL (3:1, 1:1, 1:3, 1:6, and 1:9) on the drug release characteristics were explored. Polarized light microscopy (PLM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to evaluate the solid states. Prepared C-ASDs were further studied for their stability under the high humidity (RH 92.5%). Further analysis of C-ASDs via Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy confirmed that hydrogen bond interactions between the two drugs played a significant role in maintaining the stability of the C-ASDs systems. Moreover, molecular dynamic (MD) simulations provided a clear insight into the stability mechanism at the molecular level. This study demonstrated the novel drug-drug C-ASDs systems is a promising formulation strategy for improved dissolution rate and enhanced physical stability of poorly soluble drugs. Keywords: Co-amorphous solid dispersion, Lacidipine, Spironolactone, Stability, Molecular dynamic (MD) simulation

Fabrication of Nitrogen-Doped Graphene Decorated with Organophosphor and Lanthanum toward High-Performance ABS Nanocomposites

Despite substantial advances, it remains imperative but challenging to develop high-performance polymer/graphene nanocomposites combining with excellent mechanical, thermal, and fire-retardant properties. In this work, a novel kind of graphene-based multifunctional nanofiller (La@PN-RGO) was fabricated via the nitrogen doping and the decoration with organophosphorus and lanthanum based on graphene oxide, which is then incorporated into acrylonitrile–butadiene–styrene (ABS) resin via melt blending to obtain resultant ABS nanocomposites. As expected, the La@PN-RGO nanosheets were well dispersed in ABS composites. Attractively, with only 1.0 wt % of La@PN-RGO incorporated into ABS matrix, the peak heat release rate (PHRR) and total smoke production (TSP) were significantly reduced by 38% and 36%, which is much superior to its counterparts at the same nanofillers loading level. The notably enhanced fire safety was primarily attributed to the rare earth catalysis accompanied by the lamellae blocking effect and intumescent flame retardancy of La@PN-RGO. Additionally, ABS/La@PN-RGO composite exhibited a 16% enhancement in tensile strength without at the expense of extensibility. This effective and promising method may open a new pathway to obtain high-performance polymer/graphene nanocomposites