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Magnetotactic bacteria that produce magnetic nanocrystals of uniform size and well-defined morphologies have inspired the use of biomineralization protein Mms6 to promote formation of uniform magnetic nanocrystals in vitro. Small angle X-ray scattering (SAXS) studies in physiological solutions reveal that Mms6 forms compact globular three-dimensional (3D) micelles (approximately 10 nm in diameter) that are, to a large extent, independent of concentration. In the presence of iron ions in the solutions, the general micellar morphology is preserved, however, with associations among micelles that are induced by iron ions. Compared with Mms6, the m2Mms6 mutant (with the sequence of hydroxyl/carboxyl containing residues in the C-terminal domain shuffled) exhibits subtle morphological changes in the presence of iron ions in solutions. The analysis of the SAXS data is consistent with a hierarchical core-corona micellar structure similar to that found in amphiphilic polymers. The addition of ferric and ferrous iron ions to the protein solution induces morphological changes in the micellar structure by transforming the 3D micelles into objects of reduced dimensionality of 2, with fractal-like characteristics (including Gaussian-chain-like) or, alternatively, platelet-like structures.

Three representative polymers of increasing modulus, poly(d,l-lactic acid), PDLLA, poly(desaminotyrosyl-tyrosine ethyl ester carbonate), PDTEC, and the same polymer with iodinated DTE segments, PI2DTEC, were characterized by surface-pressure versus area (Π-A) isotherms and surface sensitive X-ray diffraction techniques. Films of 10-100 Å thickness were prepared for these studies by spreading dilute polymer solutions at air-water interfaces. The general properties of the isotherms and the Flory exponents, determined from the isotherms, vary in accordance with the increasing modulus of PDLLA, PDTEC, PI2DTEC, respectively. The analysis of in situ X-ray reflectivity and grazing incidence X-ray diffraction (GIXD) measurements from films at aqueous surfaces provides a morphological picture that is consistent with the modulus of the polymers, and to a large extent, with their packing in their dry-bulk state. Large absorption of X-rays by iodine enabled X-ray spectroscopic studies under near-total-reflection conditions to determine the iodine distribution in the PI2DTEC film and complement the structural model derived from reflectivity and GIXD. These structural studies lay the foundation for future studies of polymer-protein interactions at aqueous interfaces.

Controlling interactions among nanoparticles is paramount to achieving assemblies vital to technologies seeking to exploit their cutting-edge collective properties. Although various techniques have been advanced, robust ones are necessary for upscaling nanoparticle assembly and crystallization. Here, we show that by grafting gold nanoparticles (AuNPs) with charge-end-group-thiolated poly-(ethylene glycol), we control the charge of each AuNP. Such control facilitates the formation of various two-dimensional structures of oppositely charged binary constituents at vapor/liquid interfaces. Using surface-sensitive synchrotron X-ray diffraction techniques, we established the formation of distinct checkerboard square lattice structures at a range of pH values and molar ratios of the constituents. By regulating pH, the superlattices can transform from a square to a hexagonal lattice, or vice versa, and to a single-component superstructure at the interface. Our recipe for the control of charges and their consequent interactions among nanoparticles can be readily exploited in the assembly of photonics and plasmonics devices in two and three dimensions. [ABSTRACT FROM AUTHOR]

Effect of different salt ions on the gel properties and microstructure of Mesona blumes polysaccharide (MBP)-soy protein isolates (SPI) mixed gels were investigated. Sodium and calcium ions were chosen to explore their effects on the rheological behavior and gel properties of MBP-SPI mixed gels were evaluated by using rheological, X-ray diffraction, protein solubility determination, and microstructure analysis. Results showed that the addition of salt ions change the crystalline state of gels system, the crystal of gel was enhanced at low ion concentrations (0.005–0.01 M). The two peaks of gel characteristic at 8.9° and 19.9° almost disappeared at high salt ions concentrations (0.015–0.02 M), and new crystallization peaks appeared at around 30° and 45°. The elasticity, viscosity, gel strength, water holding capacity, and thermal stability of gel were increased at low ion concentration. Results showed that the main interactions which promoted gel formation and maintain the three-dimensional structure of the gel were electrostatic interactions, hydrophobic interactions, and disulfide interactions. [ABSTRACT FROM AUTHOR]

Abstract: It is shown that magnetite nanoparticles (MagNPs) grafted with polyethylene glycol (PEG) self‐assemble and short‐range‐order as 2D films at surfaces of aqueous suspensions by manipulating salt concentrations. Synchrotron X‐ray reflectivity and grazing‐incidence small angle X‐ray scattering studies reveal that K2CO3 induces the migration of the PEG‐MagNPs to the liquid/vapor interface to form a Gibbs layer of monoparticle in thickness. As the salt concentration and/or nanoparticle concentration increase, the surface‐adsorbed nanoparticles become more organized. And further increase in salt concentration leads to the growth of an additional incomplete nanoparticle layer contiguous to the first one at the vapor/liquid interface that remains intact. [ABSTRACT FROM AUTHOR]

Glomalin-related soil protein (GRSP) is well-known for its soil conditioning functions, but compositional traits are rarely considered. Farmland in northeastern China is the most important commercial grain basis, and soil degradation becomes the bottleneck for keeping crop productivity. The objective of this study was to uncover the possible associations between GRSP (amount and composition) and soil properties, and make suggestions for soil improvement from soil glomalin rehabilitation in northeastern China. Here, spatial variation in GRSP amount (Easily-extractable-GRSP, EE-GRSP; Total-GRSP, T-GRSP) and its compositional traits from infrared spectroscopy, UV-absorbance, X-ray diffraction (XRD) and 3-D fluorescence spectroscopy were surveyed in 360 soil samples across northeastern China, and their association with 11 soil properties were also analyzed for finding the possible influence of soil properties on GRSP composition in farmland. There about 3-fold spatial variation in GRSP amount was observed, while functional group variations were ranged from 1.2-fold (O-H & N-H stretching) to 2.4-fold (C-O stretching & O-H bending of -COOH) in different locations. The XRD showed that grain size was 113-180Å and crystallinity was 0.71-1.42%, and GRSP contained seven fluorescent compounds of tyrosine-like, tryptophan-like, fulvic acid-like, soluble microbial byproduct, humic acid-like, nitrobenzoxadidole-like, and calcofluor white-like. Both, EE-GRSP and T-GRSP positively associated with soil organic carbon (SOC), soil N (SON), soil P (SOP), alkali-hydrolyzed N (AN), available P (AP), available K (AK), and soil water, while negatively associated with soil pH and soil bulk density. Structural equation model (SEM) analysis indicates that direct effects on GRSP amounts were mainly from soil bulk density (coefficient: -0.27), soil pH (coefficients: -0.51 to -0.57), SOC (coefficients: 0.51 to 0.69) and AP (coefficients: 0.18 to 0.26), while all other soil properties had indirect effects on GRSP amounts via their close associations with these four parameters. Compared with the GRSP amounts, soil properties laid fewer effects on GRSP compositional traits. Of 16 compositional traits, five of them showed possible regulations from soil properties, which were three infrared functional groups (IR-II: aliphatic C-H stretching; IR-V: C-O stretching & O-H bending of -COOH; IR-VII: O-H binding) and two fluorescent compounds (tyrosine-like and humic acid-like). SEM analysis indicates that soil water, pH and EC could directly affect IR-II, IRV, tyrosine-like and humic acid-like, while available nutrients showed more evident influences on infra-red functional groups than total amounts of N, P and K. Moreover, SOC, as a media of various soil nutrients, gave the strongest influence on GRSP compositional traits. As a supplement to previous studies, we found that GRSP is a mixture of different fluorescent compounds with different functional groups. Our findings highlight that soil properties could strongly change both GRSP accumulation in soil and their compositional traits, and the definition of the most probable soil properties in regulating glomalin amount and composition in this paper could favor good soil management in farmland at northeastern China. [ABSTRACT FROM AUTHOR]

NH 2 -MIL-53(Al) nanocrystals grown from the surface of the hollow graphene microspheres were prepared by using reduced graphene oxide (RGO) wrapped polystyrene (PS) microspheres as template and then removing the PS cores in N,N-dimethylformamide (NH 2 -MIL-53(Al)/RGO). Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and scanning electron microscopy results demonstrated the NH 2 -MIL-53(Al) nanocrystals located at the surface of the hollow graphene microspheres. Compared to NH 2 -MIL-53(Al) the NH 2 -MIL-53(Al)/RGO showed higher photocatalytic efficiency in degradation of methylene blue under visible light. [ABSTRACT FROM AUTHOR]

Abstract: The electromagnetic absorbing behaviors of a thin coating fabricated by mixing Mn–Zn ferrite with epoxy resin (EP) were studied. The spinel ferrites Mn1−x Zn x Fe2O4 (x=0.2, 0.5 and 0.8) were synthesized with citrate acid as complex agent by sol–gel combustion method. The microstructure and surface morphology of Mn–Zn ferrite powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The complex permittivity and complex permeability of the fabricated ferrite/EP composites were investigated in terms of their contributions to the absorbing properties in the low frequency (10MHz to 1GHz). The microwave absorption of the prepared ferrite/EP composites could be tailored by matching the dielectric loss and magnetic loss and by controlling the doped metal ratio. The composites with the ferrite composition x=0.2 are found to show higher reflection loss compared with the composites with other compositions. It is proposed that the prepared composites can potentially be applied in electromagnetic microwave absorbing field. [Copyright &y& Elsevier]

Abstract: Surface sensitive X-ray reflectivity (XR), fluorescence (XF), and grazing incidence X-ray diffraction (GIXD) experiments were conducted to determine the accumulation of ferric iron Fe (III) or ferrous iron Fe (II) under dihexadecyl phosphate (DHDP) or arachidic acid (AA) Langmuir monolayers at liquid/vapor interfaces. Analysis of the X-ray reflectivity and fluorescence data of monolayers on the aqueous subphases containing FeCl3 indicates remarkably high levels of surface-bound Fe (III) in number of ions per molecule (DHDP or AA) that exceed the amount necessary to neutralize a hypothetically completely deprotonated monolayer (DHDP or AA). These results suggest that nano-scale iron (hydr) oxide complexes (oxides, hydroxides or oxyhydroxides) bind to the headgroups and effectively overcompensate the maximum possible charges at the interface. The lack of evidence of in-plane ordering in GIXD measurements and strong effects on the surface-pressure versus molecular area isotherms indicate that an amorphous network of iron (hydr) oxide complexes contiguous to the headgroups is formed. Similar experiments with FeCl2 generally resulted with the oxidation of Fe (II)–Fe (III) which consequently leads to ferric Fe (III) complexes binding albeit with less iron at the interface. Controlling the oxidation of Fe (II) changes the nature and amount of binding significantly. The implications to biomineralization of iron (hydr) oxides are briefly discussed. [Copyright &y& Elsevier]

One-dimension γ-LiVO nanorods were synthesized using VO(B) nanorods as precursor in this study. The as-prepared material is characterized by X-ray diffraction, X-ray photoelectron spectrometry, Fourier-transform infrared, transmission electron microscopy (TEM), cyclic voltammetry, and charge-discharge cycling test. TEM results show that LiVO nanorods are 90-250 nm in diameter. The nanorods deliver a maximum discharge capacity of 284.3 mAh g at 15 mA g and 270.2 mAh g is maintained at the 15th cycle. Good rate performance is also observed with the discharge capacity of 250.1 and 202.6 mAh g at 50 and 300 mA g, respectively. The capacity retention at 300 mA g is 84.2% over 50 cycles. The Li diffusion coefficient of LiVO is calculated to be 10-10 cm s. It is demonstrated that the nanorod morphology could greatly facilitate to shorten lithium ion diffusion pathways and increase the contact area between active material and electrolyte, resulting in high capacity and rate performance for LiVO. [ABSTRACT FROM AUTHOR]

Abstract In this study, the effects of sodium carbonate (Na 2 CO 3) on the maize starch (MS)- Mesona chinensis polysaccharide (MCP) gels were evaluated. Na 2 CO 3 significantly accelerated pasting process and decreased viscosity of MS mixtures, however, the paste viscosity was increased with increasing concentration of MCP. Na 2 CO 3 addition resulted in higher G′ of starch gels in the presence of 0.2% of MCP compared with MS-MCP gels. X-ray diffraction spectrum showed that the relative crystallinity of MS was increased by both MCP and Na 2 CO 3 during gelatinization. The gel textural properties were improved in the presence of Na 2 CO 3 , and the microstructure of MS-MCP-Na 2 CO 3 consisted of cross distributed bigger pores with thicker pore wall. Confocal laser scanning microscopy (CLSM) confirmed the changes in granular size of MS-MCP as the starch granules tended to swell to the high degree in the presence of Na 2 CO 3. The addition of Na 2 CO 3 lead to the improvement of rheological and textural properties of MS-MCP gels, it suggested that Na 2 CO 3 could apply to the starch-non starch polysaccharide systems as gel-strengthen agent. Graphical abstract Image Highlights • The pasting of maize starch was accelerated in the presence of Na 2 CO 3. • High level MCP could inhibit negative effect induced by Na 2 CO 3. • Maize starch-MCP samples have strong gel strength in presence of Na 2 CO 3. • The Na 2 CO 3 treated gels have cross distribution pores and thicker cell walls. • CLSM showed that the granular size was enlarged in the presence of Na 2 CO 3 and MCP. [ABSTRACT FROM AUTHOR]

A copper coordination polymer with γ -aminobutyric acid (GABA), {[Cu 3 (GABA) 2 (NO 3 ) 2 (OH) 2 (H 2 O) 2 ] (NO 3 ) 2 ·2H 2 O} n (1), has been synthesized and characterized by single-crystal X-ray diffraction, IR, PXRD, TGA and elemental analysis. It exhibits a 1D chain structure including μ 3 -OH-Cu 3 cluster as a building block. The strong H-bonding links these chains to form 2D sheet structure and the main intermolecular interaction between the 2D sheets is electrostatic interaction. According to the crystal structure of complex 1 , the magnetic properties of complex 1 have been investigated by the cluster and cycle magnetic coupling models. There are three different magnetic coupling pathways of Cu(II) ( J 1 , J 2 , J 3 ) from each method and the resulting fitted curves based on the magnetic parameters of both methods compare well with the experiment values. [ABSTRACT FROM AUTHOR]

Abstract: The photoluminescence properties of Si–N doped BaMgAl10O17:Eu2+, Mn2+ phosphors were studied. Photoluminescence spectrum, powder X-ray diffraction and decay curves were used. The electronic structure of un-doped BaMgAl10O17 was investigated by using the density functional theory. It reveals that an ideal hexagonal shape and particle size in 3–5μm are obtained by Si–N doping. Additionally, its photoluminescence and thermal stability are both improved. The energy transfer from Eu2+ to Mn2+ also enhanced by suitable Si–N doping. These are expected to be potentially applicable to industrial production of the phosphor in plasma display panels. [Copyright &y& Elsevier]

Abstract: NH4V3O8·0.2H2O is synthesized by sodium dodecyl sulfonate (SDS) assisted hydrothermal method and its electrochemical performance is investigated. The as-prepared material is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared (IR) spectrum, differential scanning calorimetry and thermal gravimetry (DSC/TG), cyclic voltammetry (CV), and charge–discharge cycling test. The results show a pure NH4V3O8·0.2H2O phase with flake-like morphology is obtained and the average flake thickness is about 150nm. The NH4V3O8·0.2H2O electrode has a good lithium ion insertion/extraction ability with the highest discharge capacity of 225.9mAhg−1 during 1.8–4.0V versus Li at the constant current density of 15mAg−1. After 30 cycles, it still maintains a high discharge capacity of 209.4mAhg−1, demonstrating good cyclic stability. Interestingly, at the discharge process a new (NH4)Li x V3O8·0.2H2O compound is formed due to the new lithium ion from lithium metal anode. [Copyright &y& Elsevier]

[Display omitted] • Tunable emission colors can be realized in Sr 8 MgCe(PO 4) 7 :Tb3+. • Energy transfer occurs between the host and Tb. • The emission of Tb shows an anti-thermal quenching behavior. • The temperature sensing behavior was studied. Novel color-adjustable phosphors Sr 8 MgCe(PO 4) 7 :Tb3+ were synthesized by the solid-state reaction method. The X-ray diffraction was used to characterize the phase formation. The host shows blue emission under 310 nm excitation, ascribed to the 5d-4f transitions of Ce3+, while Sr 8 MgCe(PO 4) 7 : x Tb3+ phosphors exhibit the emission band of Ce3+ as well as the characteristic lines of Tb3+ under 310 nm excitation. The color variation was observed as the concentration of Tb3+ changes. Moreover, the host sensitizes the emission of Tb3+ through the energy transfer process, and the mechanism is the dipole–dipole interaction. In addition, the emission of the host declines with the increase of the temperature while that of Tb3+ increases. This anti-thermal quenching behavior was interpreted by the configurational coordinate diagram. In addition, the temperature sensing behavior based on the emission peaks of the host and Tb was studied in the range 298–523 K, and the largest sensitivity is 0.379% K−1. The results indicate that Sr 8 MgCe(PO 4) 7 :Tb3+ is an attractive color-tunable phosphor for solid state lighting and temperature sensing. [ABSTRACT FROM AUTHOR]