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Unusual ZnO superstructures with ring-like nanosheets standing the backbone of spindles were synthesized from Zn5(OH)(sub 8)Cl2[.]H2O nanosheets by a mild solution route. The fast supersaturation for the formation of the ZnO phase can be achieved by using the precursor, which already has rich hydroxyl groups.

An attempt made to identify that well-crystallized ZnWO4 nanorods can direct the self-aggregation of the amorphous nanoparticulates and promote the crystallization is reported. Further, the transformation of the amorphous nanoparticles derived from a simple supersaturation precipitation reaction in a nanorods/amorphous nanoparticle coexisting system under either refluxing conditions or mild hydrothermal conditions are presented.

Hydrogen is becoming a more and more crucial resource for chemical industries. Hydrogen network integration is an effective tool in hydrogen resource conservation. Hydrogen sources flow in and flow out from different processing units where consumption, generation, mixing, and separation occur. Consequently, there is a dependence on both hydrogen and contaminant species among those streams, especially when throughputs of processing units fluctuate. Hydrogen network integration should account for such a dependence so that real properties including the flow rate and concentration can be obtained to perform reliable network integration. This article proposes the processing unit mass balance to describe the dependence of hydrogen streams and establishes a corresponding superstructure as problem illustration. A mixed integer nonlinear programing (MINLP) model is built to synthesize hydrogen networks for fresh hydrogen minimization. This method considers the tolerable disturbance of the processing unit and thus a reliable fresh hydrogen target and internal sources profile can be obtained. Two cases are employed to demonstrate its application. [ABSTRACT FROM AUTHOR]

The first metal-free, three-component radical aminofluorination of styrene derivatives has been developed, which employs Selectfluor as a fluorine source and azole derivatives as a nitrogen source. This transformation proceeds with high regioselectivity, providing various 1,2-aminofluorination compounds under mild conditions. Mechanistic studies suggest that the aminofluorination process might involve radical fluorination followed by nucleophilic amination. [ABSTRACT FROM AUTHOR]

Hydrogen is a crucial and expensive resource for refineries. Hydrogen network integration is an effective way to conserve fresh hydrogen. On the basis of relative concentration analysis, a mixed integer linear programming (MILP) mathematical model is established to synthesize refinery multi-impurity hydrogen networks. By correlating the hydrogen consumption of a sink with its oil processing throughputs, this model reveals the fresh hydrogen variation tendency caused by fluctuation of each capacity, and determines the key sink(s) of a hydrogen network with multiple impurities on the premise of minimum fresh hydrogen consumption. With a structure matrix variable, practical hydrogen networks can be analyzed through the proposed model. The results show that the novel method in this paper is superior to traditional absolute concentration-based methods in fresh hydrogen conservation under cases of static, fluctuant throughputs, and fluctuant throughputs with restricted network structure. Two cases are employed to demonstrate its application. [ABSTRACT FROM AUTHOR]

The formation of a ferric hydroperoxide species from [Fe(bbpc)(MeCN)2]2+ (bbpc = N,N'-dibenzyl-N,N'-bis(2-pyridylmethyl)-1,2-cydohexanediamine) and its subsequent decomposition were analyzed kinetically. The rate of decay is not strongly influenced by the presence of either water or substrate, suggesting that the ferric hydroperoxide degrades through O--O bond homolysis and is not the relevant metal-based oxidant in the observed catalysis of C-H activation. The rate law corresponding to the complex's formation from O2 is consistent with the intermediacy of a mononuclear ferric superoxo species. [ABSTRACT FROM AUTHOR]

The compound N,N'-dineopentyl-N,N'-bis(2-pyridylmethyl)-1,2-ethanediamine (dnbpn) and its ferrous complex [Fe(dnbpn)(OTf)2] were synthesized. The Fe(II) complex was used to catalyze the oxidation of hydrocarbons by H2O2 and O2. Although the catalyzed alkane oxidation by H2O2 displays a higher preference for secondary over tertiary carbons than those associated with most previously reported nonheme iron catalysts, the catalytic activity is markedly inferior. In addition to directing the catalyzed oxidation toward the less sterically congested C-H bonds of the substrates, the neopentyl groups destabilize the metal-based oxidants generated from H2O2 and the Fe(II) complex. The presence of benzylic substrates with weak C-H bonds stabilizes an intermediate which we have tentatively assigned as a high-spin ferric hydroperoxide species. The oxidant generated from O2 reacts with allylic and benzylic C-H bonds in the absence of a sacrificial reductant; less substrate dehydrogenation is observed than with related previously described systems that use O2 as a terminal oxidant. [ABSTRACT FROM AUTHOR]

In this work, we reported a simple rapid and point-of-care magnetic immunofluorescence assay for avian influenza virus (AIV) and developed a portable experimental setup equipped with an optical fiber spectrometer and a microfluidic device. We achieved the integration of immunomagnetic target capture, concentration, and fluorescence detection in the microfluidic chip. By optimizing flow rate and incubation time, we could get a limit of detection low up to 3.7 × 104 copy/μL with a sample consumption of 2 μL and a total assay time of less than 55 min. This approach had proved to possess high portability, fast analysis, high specificity, high precision, and reproducibility with an intra-assay variability of 2.87% and an interassay variability of 4.36%. As a whole, this microfluidic system may provide a powerful platform for the rapid detection of AIV and may be extended for detection of other viral pathogens; in addition, this portable experimental setup enables the development of point-of-care diagnostic systems while retaining adequate sensitivity. [ABSTRACT FROM AUTHOR]

The ligand N,N′-bis(2-pyridylmethyl)-bis(ethylacetate)-1,2-ethanediamine (debpn) coordinates divalent transition metal ions in either a pentadentate or hexadentate fashion. The coordination number correlates with the ionic radius of the metal ion, with larger cations being heptacoordinate as assessed by solid-state analysis. With Mn(II), the debpn ligand is hexadentate and remains bound to the oxophilic metal ion, even when dissolved in water. The ligand's incomplete coordination of the manganous ion allows water molecules to coordinate to the metal center. These two properties, coupled with the high paramagnetism associated with the S = 5/2 metal center, enable [Mn(debpn)(H2O)](ClO4)2 to serve as a stable and effective magnetic resonance imaging contrast agent despite the ligand's lack of both a macrocyclic component and an anionic charge. [ABSTRACT FROM AUTHOR]

Silver nanoplates with an extremely high aspect ratio (up to over 400) and a widely tunable surface plasmon resonance (SPR) band have been successfully synthesized by combining the concepts of selective ligand adhesion and seeded growth. Citrate ligands are used as the sole surfactant to effectively block overgrowth on the basal {111} facets and only allow growth in the lateral direction. By slowing down the reaction rate using Ag−citrate complex as precursor, the thin nature of Ag nanoplates is maintained with the edge length grown up to 4 μm, which ensures the high aspect ratio and the widely tunable SPR band. We also observe a size distribution focusing effect that helps to produce uniform nanoplates as well as narrow SPR bands over a wide range, which is important in many practical applications. [ABSTRACT FROM AUTHOR]

We describe a “surface-protected etching” strategy that allows convenient conversion of sol−gel derived silica into porous structures. Poly(vinyl pyrrolidone) is used to protect the near surface layer, and NaOH is used to selectively etch the interior of the silica spheres. Etching initially yields porous structures and eventually removes the core to leave behind hollow silica spheres with porous shells. This strategy is useful for constructing core−shell systems where active nanomaterials are embedded in silica shell for enhanced stability against aggregation. We experimentally demonstrate use of the surface-protected etching approach to create openings on silica shells; these openings allow dissolved chemical species to reach embedded catalytic particles to be chemically transformed while the porous shells continue to act as effective barriers against aggregation and loss of activity of the core particles. We also show that, by controlling the extent of etching, it is possible to control the permeation rate of the chemical species through the shells. [ABSTRACT FROM AUTHOR]

Nearly monodisperse PbWO4and CaWO4microspheres have been synthesized in large scale by a surfactant-assisted solution route, in which either sodium dodecyl benzenesulfonate (SDS) or cetyltrimethyl ammonium bromide (CTAB) is used. By controlling the solution reaction conditions, such as temperature, surfactant, and pH value, we can synthesize nearly monodisperse microspheres of tetragonal tungstate (MWO4, M Pb, Ca) composed of subunits with different shapes. The diameters of these microspheres have been found to be sensitive to the reaction conditions and could be tuned by controlling the reaction conditions. The growth process of these nearly monodisperse microspheres has been examined. The optical properties of the tungstate monodisperse microspheres in the temperature range of 20−270 K were studied. [ABSTRACT FROM AUTHOR]

The demand for catalyst with higher activity and higher selectivity is still a central issue in current material science community. On the basis of first-principles calculations, we demonstrate that the catalytic performance of the Pd-TiO2 hybrid nanostructures can be selectively promoted or depressed by choosing the suitable shaped Pd and TiO2 nanocrystals. To be more specific, the catalytic activities of Pd nanoparticles enclosed by (100) or (111) facets can be promoted more significantly when dosed on the TiO2(001) than on TiO2(101) under irradiation. Such theoretical prediction has then been further verified by the experimental observations in which the Pd(100)-TiO2(001) composites exhibit the highest catalytic performance toward the activation of oxygen among all the other shaped hybrid nanostructures. As a result, the selection of facets of support materials can provide an extra tuning parameter to control the catalytic activities of metal nanoparticles. This research opened up a new direction for designing and preparing catalysts with enhanced catalytic performance. [ABSTRACT FROM AUTHOR]