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The low capacity and unsatisfactory rate capability of hard carbon still restricts its practical application for Li/K‐ion batteries. Herein, a low‐cost and large‐scale method is developed to fabricate phosphorus‐doped hard carbon (PHC‐700) by crosslinking phosphoric acid and epoxy resin and followed by annealing at 700 °C. H3PO4 acts not only as a crosslinker to solidify epoxy resin for promoting the degree of graphitization and lowering the specific surface area, but also as phosphorus source for forming PC and PO bonds, thus providing more active sites for Li/K storage. As a result, the PHC‐700 electrode delivers a highly reversible capacity of 1294.8 mA h g−1 at 0.1 A g−1 and a capacity of 214 mA h g−1 after 10 000 cycles at 10 A g−1. As for potassium‐ion batteries, PHC‐700 exhibits a reversible capacity of 381.9 mA h g−1 at 0.1 A g−1 and a capacity of 260 mA h g−1 after 1000 cycles at 0.2 A g−1. In situ Raman and in situ NMR measurements reveal that the P‐containing bonds can enhance the adsorption to alkali metal ions, and the PC bond can participate in electrochemical redox reaction by forming Lix PCy . Additionally, P‐doped hard carbon shows better structural/interfacial stability for improved long‐term cycling stability.

Development of novel surface-enhanced Raman scattering (SERS) substrates and how they interface target analytes plays a pivotal role in determining the spectrum profile and SERS enhancement magnitude, as well as their applications. We present here the seed-mediated growth of reduced graphene oxide-gold nanostar (rGO-NS) nanocomposites and employ them as active SERS materials for anticancer drug (doxorubicin, DOX) loading and release. By this synthetic approach, both the morphology of rGO-NS nanohybrids and the corresponding optical properties can be precisely controlled, with no need of surfactant or polymer stabilizers. The developed rGO-NS nanohybrids show tunable optical properties by simply changing growth reaction parameters, improved stability as compared to bare Au nanostars, and sensitive SERS response toward aromatic organic molecules. Furthermore, SERS applications of rGO-NS to probe DOX loading and pH-dependent release are successfully demonstrated, showing promising potential for drug delivery and chemotherapy.

Four kinds of 13C-labeled polyacrylonitrile (PAN) samples were prepared respectively by solution polymerization of acrylonitrile (AN) with selective 13C labeling of different molecular sites. The composition and structure of the residues from the thermal treatment of PAN in argon at 250 and 350 °C were quantitatively analyzed in detail by one- and two-dimensional solid-state 13C nuclear magnetic resonance (ssNMR) experiments. Compared with the NMR spectrum of each labeled carbon in AN monomer unit, nine chemical structures created during the heat treatment process have been identified accurately. On this basis, four reaction routes were proposed. It is noted that the main chemical change for PAN started from a cyclization reaction at a relatively low temperature, then experienced an aromazation reaction to form a molecular chain basically composed of isolated pyridine units, instead of the commonly reported ladder structure. This work also shows that the combination of selectively 13C-labeled technique and a high spinning speed of 20 kHz in magic-angle spinning (MAS) NMR experiment could improve the detection sensitivity to nearly 2 orders of magnitude, and provide a clear ssNMR spectra with little peak overlaps, which will be helpful to discover the complex reaction mechanism in the manufacture of carbon fibers with high performance.

[1] Laboratory and numerical studies were conducted to investigate the transport and fate of Escherichia coli D21g and coliphage 'X174 in saturated soils with preferential flow under different solution ionic strength (IS ¼ 1, 5, 20, and 100 mM) conditions. Preferential flow systems were created by embedding a coarse-sand lens (710 mm) into a finer matrix sand (120 mm). Complementary transport experiments were conducted in homogeneous sand columns to identify controlling transport and retention processes, and to independently determine model parameters for numerical simulations in the heterogeneous experiments. Results from homogeneous and heterogeneous transport experiments demonstrate that retention of E. coli D21g and 'X174 increased with IS, while the effect on E. coli D21g in finer sand was much greater than in coarse sand. This microbe transport behavior was well described by numerical simulations. The importance of preferential flow on microbe transport was found to be enhanced at higher IS, even though the overall transport decreased. However, the contribution of preferential flow was much higher for E. coli D21g than 'X174. Deposition profiles revealed significant cell retention at the interface of the coarse-sand lens and the fine-sand matrix as a result of mass transfer. Cell release from the preferential flow system with a reduction of solution IS exhibited multipulse breakthrough behavior that was strongly dependent on the initial amount of cell retention, especially at the lens-matrix interface.

Structures composed of SiO x F6–x (x = 1, 2, 3, 4, 5) or SiO x F4–x (x = 1, 2, 3) species have thus far been observed in only a few compounds, and their functional properties are completely unknown in silicate chemistry. By introducing the least electronegative element, cesium, and the most electronegative element, fluorine, into the silicophosphate system, we successfully designed the first noncentrosymmetric fluorooxosilicophosphate with Si–F bonds, CsSiP2O7F, whose structure consists of an unprecedented SiP2O10F moiety containing hexacoordinate SiO5F species. The experimental results highlight CsSiP2O7F as the first fluorooxosilicophosphate deep-UV nonlinear optical (NLO) material. The first-principles calculations reveal that the SiP2O10F moiety is a new type of NLO-active unit and that both cesium and fluorine increase the deep-UV transparency of CsSiP2O7F. This work provides a new source of deep-UV NLO materials and insights into obtaining noncentrosymmetric structures that are indispensable to functional materials in nonlinear optics, piezoelectricity, ferroelectric, pyroelectricity, etc.

A conjugated polyelectrolyte (CPE)‐silver nanoparticle platform for DNA‐sensing applications is fabricated (see figure), which provides over 17‐fold enhancement of dye emission intensity, as compared to the intrinsic dye emission observed atop a conventional glass surface. Examination of the distance‐dependence amplification process reveals that the role of the silver nanoparticles is to increase the effective field experienced by the light‐harvesting CPE, and the metal enhanced fluorescence of the CPE could be translated into higher dye signal intensities for the detection platform.

Many retailers designate one national brand manufacturer in each product category as a "category captain" to help manage the entire category. A category captain may perform demand-enhancing services such as better shelf arrangements, shelf-space management, and design and management of in-store displays. In this paper, we examine when and why a retailer may engage one manufacturer exclusively as a category captain to provide such service and the implications. We find that demand substitutability of competing brands gives rise to a service efficiency effect--service that expands the category is more effective in increasing a manufacturer's sales and margin than service that shifts demand from a rival's brand. We show that the service efficiency effect may motivate a category captain to provide a service that benefits all brands in the category even though doing so is more costly. We further show that, in categories that are less price competitive, there is higher competition between manufacturers to become the category captain. Consequently, a retailer may obtain better service by using a category captain than by engaging both manufacturers simultaneously. Our findings may help explain why a retailer may rely on a category captain despite concerns regarding opportunism and why there is limited empirical evidence of harm to rival manufacturers.category management, delegation, distribution channels, retailing, suppy chain collaboration