No abstract

Rechargeable lithium-ion batteries (LIBs) have attracted tremendous attention over the past two decades. [1][2][3][4][5] Given their relatively high cost, as well as their high energy and power densities, LIBs have been considered the most promising technology in small/mid-size applications such as portable devices and electric vehicles (EVs). They are not favourable power options for large-scale stationary energy storage, however, such as in electrical grids. [6][7][8] Various emerging energy storage systems, including lithium-air batteries, [9][10][11][12][13][14][15][16] lithium-sulfur (Li/S) batteries, [11,[17][18][19][20][21][22][23] vanadium redox batteries, [24][25][26][27][28][29][30][31] sodium-ion batteries (SIBs), [32][33][34][35][36][37][38][39][40] and room-temperature sodium-sulfur Room temperature sodium-sulfur (RT-Na/S) batteries have recently regained a great deal of attention due to their high theoretical energy density and low cost, which make them promising candidates for application in large-scale energy storage, especially in stationary energy storage, such as with electrical grids. Research on this system is currently in its infancy, and it is encountering severe challenges in terms of low electroactivity, limited cycle life, and serious self-charging. Moreover, the reaction mechanism of S with Na ions varies with the electrolyte that is applied, and is very complicated and hard to detect due to the multi-step reactions and the formation of various polysulfides. Therefore, understanding the chemistry and optimizing the nanostructure of electrodes for RT-Na/S batteries are critical for their advancement and practical application in the future. In the present review, the electrochemical reactions between Na and S are reviewed, as well as recent progress on the crucial cathode materials. Furthermore, attention also is paid to electrolytes, separators, and cell configuration. Additionally, current challenges and future perspectives for the RT-Na/S batteries are discussed, and potential research directions toward improving RT-Na/S cells are proposed at the end.

The emerging field of optical-triggered actuators based on polymeric nanocomposite continues to be the focus of considerable research in recent years because of their scientific and technological significance. In principle, dispersing nanofiller with unique characteristics in polymer matrix can not only provide superb enhancement of performance but also afford novel actuation schemes to the systems. Graphene, combining its unusual electrical, thermal, mechanical, and optical properties, can provide the ability to act as "energy transfer" and trigger unit in the realm of nanocomposite actuators. Herein, we demonstrate a new dimension to this 2D nanoscale material by showing the excellent light-triggered acutation of its thermoplastic polyurethane nanocomposites with significantly enhanced mechanical properties. These nanocomposite actuators with 1 wt % loading of sulfonated functionalized graphene sheets (sulfonated-graphene) exhibit repeatable infraredtriggered actuation performance which can strikingly contract and lift a 21.6 g weight 3.1 cm with 0.21 N of force on exposure to infrared light and demonstrate estimated energy densities of over 0.33 J/g. Some cases can even reach as high as 0.40 J/g. Dramatic improvement in mechanical properties is also obtained for the graphene nanocomposites with homogeneous dispersion. As the concentration of sulfonated-graphene increases, its nanocomposites show significantly enhanced mechanical properties, that is, the Young's modulus increases by 120% at only 1 wt % loading. Moreover, through comparative study of three kinds of graphene materials, it is found that this infrared-triggered actuation property is principally dependent on the integrity of the aromatic network of graphene and on its dispersion state within the matrix.

In 2006, more than 55,000 patients died of colorectal cancer in the US, accounting for approximately 10% of all cancer deaths. Despite significant progress in screening combined with the development of novel effective therapies, colorectal cancer ranks second to lung cancer as a cause of cancer death. Twin studies indicate that 35% of all colorectal cancers are inherited, but high-penetrance tumor susceptibility genes only account for approximately 3-6% of all cases. The remainder of the unexplained familial risk is presumably due to other high-penetrance genes, but polygenic mechanisms and low-penetrance tumor susceptibility genes are likely to account for a greater proportion of familial colorectal cancers. In this regard, there is growing evidence that a common hypomorphic variant of the type I TGF-beta receptor, TGFBR1*6A, may account for approximately 3% of all colorectal cancer cases, a fraction higher than that attributable to mismatch repair genes MLH1, MSH2, MSH6 and PMS2. Furthermore, TGFBR1*6A is emerging as a potent modifier of colorectal cancer risk among individuals with a strong family of colorectal cancer. The TGF-beta signaling pathway plays a central but paradoxical role in the predisposition and progression of colorectal cancer. TGF-beta is a potent inhibitor of normal colonic epithelial cells acting as a tumor suppressor. However, TGF-beta promotes the survival, invasion and metastasis of colorectal cancer cells, thereby acting as an oncogene. Understanding how selective alterations of the TGF-beta signaling pathway contribute to colorectal cancer development and progression will likely permit the identification of an additional fraction of inherited colorectal cancer cases and provide novel opportunities for therapeutic intervention.

The nonlinear optical properties of two novel graphene nanohybrid materials covalently functionalized with porphyrin and fullerene were investigated by using the Z-scan technique at 532 nm in the nanosecond and picosecond time scale. Results show that covalently functionalizing graphene with the reverse saturable absorption chromospheres porphyrin and fullerene can enhance the nonlinear optical performance in the nanosecond regime. The covalently linked graphene nanohybrids offer performance superior to that of the individual graphene, porphyrin, and fullerene by combination of a nonlinear mechanism and the photoinduced electron or energy transfer between porphyrin or fullerene moiety and graphene.

The nonlinear optical properties of graphene oxide (GO) were investigated at 532 nm in nanosecond and picosecond regimes. Results show that two-photon absorption dominates nonlinear absorption process of GO in the case of picosecond pulses, while excited state nonlinearities play an important role in the case of nanosecond pulses. Additionally, we compared nonlinear optical properties of three different dimensional carbon-based materials (two-dimensional graphene, one-dimensional carbon nanotube, and zero-dimensional fullerene) in nanosecond and picosecond regimes, respectively. The nonlinear mechanism of GO is distinctly different from nonlinear scattering of carbon nanotube and excited state nonlinearity of fullerene.

A novel hybrid material prepared from graphene and poly (3,4-ethyldioxythiophene) (PEDOT) shows excellent transparency, electrical conductivity, and good flexibility, together with high thermal stability and is easily processed in both water and organic solvents. Conductivities of the order of 0.2 S / cm and light transmittance of greater than 80% in the 400 1800 nm wavelength range were observed for fi lms with thickness of tens of nm. Practical applications in a variety of optoelectronic devices are thus expected for this transparent and fl exible conducting graphene-based hybrid material.

Although considerable efforts have been made in the selective conversion of syngas [carbon monoxide (CO) and hydrogen] to olefins through Fischer-Tropsch synthesis (FTS), ~50% of the converted CO is transformed into the undesired one-carbon molecule (C1) by-products [carbon dioxide (CO2) and methane (CH4)]. In this study, a core-shell FeMn@Si catalyst with excellent hydrophobicity was designed to hinder the formation of CO2 and CH4. The hydrophobic shell protected the iron carbide core from oxidation by water generated during FTS and shortened the retention of water on the catalyst surface, restraining the side reactions related to water. Furthermore, the electron transfer from manganese to iron atoms boosted olefin production and inhibited CH4 formation. The multifunctional catalyst could suppress the total selectivity of CO2 and CH4 to less than 22.5% with an olefin yield of up to 36.6% at a CO conversion of 56.1%.