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Enhancing catalytic performance as well as reducing catalyst cost are the eternal pursuit for the catalysis community. Herein, a simple and effective palladium-doped cobalt (Pd/Co) catalyst with high Pd atom utilization efficiency was synthesized via galvanic replacement reaction for the selective hydrogenation of nitrobenzene with H2 at room temperature, delivering99% yield of aniline with up to 158 times higher catalytic activity than commercial palladium powder. Detailed characterizations and DFT calculations revealed that Co-Pd interaction leads to a decrease in electron density of Pd and the distance between Pd atoms that results in the enhanced catalytic performance. Further experiments indicated that the Pd/Co catalyst serves as a highly efficient, selective, and recyclable catalyst for a range of nitroarene substrates. This work might provide a green and sustainable methodology to design and synthesize highly active catalysts with high utilization efficiency of the noble metals in fundamental and applied research.

A series of binary g-C3N4/Bi2WO6 hybrid photocatalysts with different ratios of g-C3N4 were successfully prepared using a facile hydrothermal method. The composition, structure, and optical properties of the obtained g-C3N4/Bi2WO6 composite photocatalysts were characterized by various analytical techniques including infrared spectroscopy, X-ray diffraction, UV-vis diffuse reflectance spectroscopy, N2 adsorption-desorption measurements, X-ray photoelectron spectroscopy, and scanning electron microscopy. The photocatalytic activity of the as-prepared samples were evaluated in the reduction of toxic Cr(VI) to Cr(III) under visible light irradiation. Among all the tested catalysts, 1:15-g-C3N4/Bi2WO6 nanocomposite displays the highest photocatalytic activity with the optimal rate constant of 0.0414 min−1 due to the high surface area and the improvement of visible light absorbing capacity. The composite also shows good photostability and reusability after five cyclic experiments. Different scavengers such as citric acid, oxalic acid, and isopropanol were used to systematically investigate their effect on Cr(VI) photoreduction. Appropriate concentrations of citric acid and oxalic acid have positive effect to improve the photocatalytic activity by consuming photo-induced electrons to minimize the rate of electron-hole recombination, but excessive citric acid and oxalic acid are harmful to the photoreduction. A possible mechanism for Cr(VI) photoreduction by g-C3N4/Bi2WO6 composite was proposed.

Two novel dioxygen heptaoxomolybdates K 5 [Mo 7 O 22 (O 2 )(OH)]Cl·6H 2 O ( 1 ) and K 5 [Mo 7 O 22 (O 2 )(O 2 )]·8H 2 O ( 2 ) were isolated from the solution of peroxo molybdate accidently. The solids were characterized by IR, EPR and X-ray single crystal analysis. Complex 1 contains a superoxo group with a short bond distance 1.27(1) A, while 2 is a mixed complex with peroxo and superoxo groups [1.43(1), 1.27(1) A]. All of the dioxygen groups coordinate to molybdenum atoms in side-on (η 2 ) fashion. The two complexes are short-lived and will decompose into peroxo molybdates K 5 [Mo 7 O 21 (O 2 ) 2 (OH)]·6H 2 O ( 3 ) and K 6 [Mo 7 O 22 (O 2 ) 2 ]·9H 2 O ( 4 ) very quickly.

A fluorescent-tagged and carboxyl-terminated hyper-branched waterborne polyester (HBP-AP) was prepared and characterized. Acted as CaSO4 scale inhibitor, its application conditions such as the dosage, Ca2+ concentration and pH value, were investigated to optimize the scale inhibition efficiency. In order to provide some theoretical supports for the scale inhibition mechanism of hyper-branched polymers, the scale inhibition mechanism for CaSO4 was then investigated in detailed. The experimental results showed that the HBP-AP provided an excellent scale inhibiting efficiency for CaSO4, which was as high as 98.8 % at dosage of 15 mg/L, and performed well both at high Ca2+ concentration and extended pH value. Besides, the HBP-APTA showed good solubilizing property and dispersion ability. The XRD, SEM and CLSM have been used to character the CaSO4 scale crystal. Especially, with the help of CLSM technology, it is convenient to observe how the prepared hyper-branched inhibitor affected both the CaSO4 crystal nucleation process and crystal growing process, allowing us to understand the scale inhibition mechanism easily for its leading the scale inhibition process visualization.

Since the late 1990s, a climate shift has occurred over the tropical Pacific that is characterized with a La Nina-like mean state. Coincident with this climate shift, climate models’ skills in predicting the El Nino Southern Oscillation (ENSO) events in the 2000s are significantly lower than in the 1980s–1990s. A common bias is likely to exist in contemporary ENSO models that got amplified after the climate shift. In this study, we identify this model bias to be the wind–sea surface temperature coupling processes over the tropical Pacific. Evidence is presented to show that this coupling process experienced an obvious shift around year 2000 in its coupling strength and coupling center. A simple ENSO coupled model is used to demonstrate that the changing properties of the post-2000 ENSO events can be more realistically simulated if this model bias is alleviated.

Temperature-dependent reactions of molybdates with histidine in weak acidic solution resulted in the isolations of coordinated and uncoordinated products Na[MoΛO3(S-His)]·H2O (1) (HHis = histidine, C6H9N3O2) and K4(S-H2His)2(Mo7O24)·16H2O (2) respectively. The former 1 can be reduced by hydrazine hydrochloride for the preparation of molybdenum(V) histidine [Mo2O4(S-His)2]·3H2O (3) with dinuclear [Mo2O4]2+ core. The complex 2 shows strong hydrogen bonds between molybdate and histidine. The solution behaviors of the complexes were probed and compared between solid and solution 1H and 13C NMR spectra. Obvious dissociation of histidine in 1 has been observed for 35%, showing the equilibrium between the coordinated and free histidine groups. This may support the liability of coordinated imidazole in histidine with iron-molybdenum cofactor. Furthermore, solid CD spectra show 1 and 3 with positive and negative Cotton effects respectively.

Nitrogenase catalyzes the reduction of dinitrogen to ammonia in the process of biological nitrogen fixation. In the past few decades, its catalytic mechanism and chemical simulation have been widely studied. The high resolution X-ray structural analysis of the MoFe protein in nitrogenase reveals the iron molybdenum cofactor (FeMo-co) as a cage structure, MoFe7S9C( R -homocit). The molybdenum atom is coordinated by three sulfur atoms, a nitrogen atom from histidine residue and two oxygen atoms from R -homocitrate. Recently, the model has been modified as a protonated structure of MoFe7S9C( R -Hhomocit). Homocitrate and imidazole sidechain may play important roles in delivering proton and stabilizing the MoFe7S9C cluster in the process of N2 reduction. However the mechanism of N2 reduction remains unclear. In this review, the chemistry of molybdenum with homocitrate and imidazole is discussed, including the iron molybdenum sulfur complexes, which will be helpful to understand the coordination environment of molybdenum atom in iron molybdenum cofactor.

Investigations on aminopolycarboxylato molybdates resulted in the isolation of two interesting decameric species of iminodiacetato γ-octamolybdates (NH4)8{γ-Mo8O26[MoO3(ida)]2}·6H2O (1) (H2ida = iminodiacetic acid) and its partially reduced form, K8{γ-Mo8VI/VO26[MoVO2(ida)]2}·12H2O (2). 1 is comparable with its formal polymeric coupling form of polyaminopolycarboxylato molybdate (NH4)8n{γ-Mo8O26[Mo2O6(1,3-pdta)]}n·30nH2O (3) from 1,3-propanediaminetetraacetate (H4pdta = 1,3-propanediaminetetraacetic acid). The basic construction unit of the iminodiacetato γ-octamolybdates was isolated as a monomeric complex (NH4)4[MoO3(ida)]2·3H2O (4). While those for propanediaminetetraacetato γ-octamolybdate are a dimeric species of (NH4)5[Mo2O6(1,3-pdta)]Cl·2H2O (5) and K4[Mo2O6(1,3-pdta)]·3H2O (6) respectively. Moreover, polymeric octamolybdates with ammonium cations (NH4)6n(Mo8O27)n·4nH2O (7) and (NH4)4n(Mo8O26)n (8) were obtained under heating and hydrothermal conditions, respectively. Monomeric iminodiacetato molybdate 4 can be transformed to its decanuclear species 1 with [Mo8O26]4− anion. Mixed-valence complex 2 processes a unique deca-molybdenum core with a metallic Mo(V)–Mo(V) bond [2.573(2) A]. The complexes have been characterized by elemental analyses, spectral, X-ray structural analyses and bond valence calculations. Complexes 1–6, except for 3, showed an obvious decomposition in solution, based on solution 13C NMR observations. NMR analyses revealed that the γ-Mo8O26 units in 1 and 2 show an effect on the carbon signals. This is attributed to the Mo–O–Mo bond between the Mo8O26 and MoO3ida units. The dimeric species 5 and 6 dissociated to free ligands in ∼5% and ∼27%, respectively, based on 1H NMR spectra.

Two novel dioxygen heptaoxomolybdates K 5 [Mo 7 O 22 (O 2 )(OH)]Cl·6H 2 O ( 1 ) and K 5 [Mo 7 O 22 (O 2 )(O 2 )]·8H 2 O ( 2 ) were isolated from the solution of peroxo molybdate accidently. The solids were characterized by IR, EPR and X-ray single crystal analysis. Complex 1 contains a superoxo group with a short bond distance 1.27(1) A, while 2 is a mixed complex with peroxo and superoxo groups [1.43(1), 1.27(1) A]. All of the dioxygen groups coordinate to molybdenum atoms in side-on (η 2 ) fashion. The two complexes are short-lived and will decompose into peroxo molybdates K 5 [Mo 7 O 21 (O 2 ) 2 (OH)]·6H 2 O ( 3 ) and K 6 [Mo 7 O 22 (O 2 ) 2 ]·9H 2 O ( 4 ) very quickly.

Polyaniline (PANI) and p-phenylenediamine (p-PDA)-aniline copolymer were prepared via a same microemulsion method. The structures of the PANI and p-PDA-aniline copolymer were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis（TGA）. The results revealed the difference of synthesis and characterization between PANI and p-PDA-aniline copolymer. It was shown that structure of the copolymer is almost similar to that of PANI, but the p-PDA-aniline copolymer has a better crystallization than PANI, and the thermal stability of the copolymer is higher than that of pure PANI.

National Natural Science Foundation of China ; National Basic Research Program of China [2005CB221408, 2010CB732303]

Water pollution has caused much attention nowadays. Photocatalysis as a kind of advanced oxidation technology has been widely studied in the field of environmental pollution control. As a stable non-metal photocatalyst, the photocatalytic activity of g-C3N4 assisted by H2O2 was investigated for the degradation of Rhodamine B (RhB) under visible light irradiation. The combination of g-C3N4 and H2O2 has much higher activity than that of pure g-C3N4 or H2O2. Neutral solution is preferred for the high phtotocatalytic activity of g-C3N4 with H2O2. The effect of the amount of catalyst, H2O2 concentration and RhB concentration was investigated. Photocatalytic mechanism study using radical scavenger showed free radicals and OH are the main active species. g-C3N4 assisted by H2O2 showed good photostability and repeatability after five cycles of degradation experiment.

To develop Web applications of high quality, it is important to apply efficient frameworks to standardize the process of development in projects, or apply useful design patterns to produce the program code that can easily be enhanced. In addition to these efforts, we have to check the programs to see whether they keep various kinds of rules such as verification items for security which are common for all kinds of Web applications, and verification items for coding styles or code conventions which pertain to each project. This paper proposes a verification method for an extensible syntax-oriented verifier, and describes the implementation of its prototype system, SyntaxVerifier. SyntaxVerifier makes it possible to detect syntactical objects based on their syntactic contexts. It realizes a context-dependent recursive verification which makes it easy to dynamically trace a syntax tree in a verification process itself.

The ECMWF and HALOE data from 1991 to 2002 was used to research the stratospheric temperature profile and distribution of temperature difference square. Then the time trends of stratospheric temperature at some altitudes were interviewed through linear trend test. The results obtained show that there are obvious differences between ECMWF and HALOE data. In mid-low latitudes, the temperature profiles are very similar below 10 hPa and the temperature from HALOE data is higher than that from ECMWF data in the layer from 10 hPa to 2 hPa. At 1 hPa, there is little difference between them. In mid-high latitudes of both hemispheres, the temperature difference is relatively obvious. The temperature from HALOE data is higher than that from ECMWF data in the whole stratosphere. It can be also found that the temperature distribution difference increases with the altitude in the stratosphere. There is a little difference in mid-low latitudes and clear differences out of 50 degrees in both hemispheres. At 100 hPa, 50 hPa and 10 hPa in the mid-low stratosphere, the temperature trends from HALOE and ECMWF data are very similar, but the decreasing trend is more obvious from HALOE data. At 2 hPa in the upper stratosphere, the temperature trends after 1996 from the two datasets are just opposite. Those results will provide some basis for data selection in stratospheric temperature researches.

Super Absorbent Polymer is a new type of functional polymer material developing at a high speed since the late 70’s. It can absorb water quickly . After absorbing water it becomes a kind of achromatic hydromel, and the absorbed should be: water is hard to remove even under pressure. As a result, it is usually referred as high-absorbent polymer, super absorbent polymer retention or super absorbent polymer unnecessary . This study is concerned methods of preparation and application areas of water absorbency, the influence of the initiating agent and cross-linking agent amount on the water absorbency. When the initiating agent, cross-linking agent ratio were respectively 0. 4% and 0. 2%, the water absorbency was highest. The reversibility of PH is also discussed, as well as the best methods of preparing high-water-absorbent resin cut this.

Substitutions of trans-Na(Him)[Mo(2)O(4)(ox)(2)(H(2)O)(2)]·H(2)O (1) and trans-(Him)(2)[Mo(2)O(4)(ox)(2)(H(2)O)(2)] (2) with imidazole result in the formation of the mixed-ligand molybdenum complexes cis-Na(2)[Mo(2)O(4)(ox)(2)(im)(2)]·4.5H(2)O (3), cis-K(2)[Mo(2)O(4)(ox)(2)(im)(2)]·3H(2)O (4), respectively (H(2)ox = oxalic acid; im = imidazole). Further reduction of cis-K(2)[Mo(2)O(4)(ox)(2)(im)(2)]·3H(2)O (4) gives a trinuclear molybdenum(IV) complex K(Him)[Mo(3)O(4)(ox)(3)(im)(3)]·3H(2)O (5), which contains an incomplete cubane cluster [Mo(IV)(3)O(4)](4+). Two novel trinuclear mixed-valence imidazole compounds [Mo(3)O(8)(im)(4)](im)·H(2)O (6) and [Mo(3)O(8)(im)(4)]·H(2)O (7) were obtained by the reduction of (Him)(4)[Mo(8)O(26)(im)(2)] (8). Both 6 and 7 contain a novel Mo(VI)O(4)(Mo(V)(2)O(4)) center, where the [Mo(V)(2)O(4)](2+) unit is linked by [Mo(VI)O(4)](2-) anion. The Mo-Mo bond distances in 1-7 decrease with the decrease of oxidation state of molybdenum. Solid and solution NMR spectra show that imidazole molybdenum compounds 6-8 fully dissociate in solution, where solvated imidazole and imidazolium groups in 6 and 8 could be served as internal references in their solid (13)C NMR spectra. Furthermore, mixed-ligand molybdenum species 3 and 4 are stable in water. Stabilities of 3 and 4 in solution may be attributed to the strong coordination of bidentate oxalate and the formation of hydrogen bond. Dimers 2 and 4 display quasi-reversible redox process, while trimer 6 is irreversible. Bond valence calculations for 1-8 are consistent with their oxidation states of molybdenum atoms. Calculation of the oxidation state in recent structure of iron molybdenum cofactor [MoFe(7)S(9)C(R-homocit)] (FeMo-co) is 3.318.

This paper presents high-level functional Web components,which conventional development environments for Web applications have not yet supported. The high-level functional Web components sum up various kinds of data in two dimensions as in Microsoft Excel. These components reduce the amount of code to be written by developers greatly. The paper also describes the system that implements these high-level functional components as visual Web components. This system assists in the development of Web applications based on a page-transition framework that regards a Web application as a sequence of Web page transitions.By using visual Web components, the system makes it easier to write actions executed when a Web page transfers to another.