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A new selenite compound CaNi2(SeO3)3·2H2O (1) was obtained by a conventional hydrothermal method, featuring a distorted zemannite-type structure with a unique honeycomb-like hexagonal framework. The crystal-to-crystal transformation from 1 to a partially dehydrated form of CaNi2(SeO3)3·1.5H2O (2) with slightly shrunk hexagonal framework and further to an anhydrous CaNi2(SeO3)3 (3) with a square framework can be achieved by step-by-step dehydration under heating. The UV-vis-NIR absorption spectra indicate that all 1–3 to possess a wide band gap due to spin allowed d–d transition at Ni2+ ion centers. Further, magnetic measurements show a similar magnetic behavior with an antiferromagnetic transition in 1 and 2, while a different magnetic behavior with two magnetic transitions is observed in 3.

Two new selenite compounds Ca2Ni(HSeO3)2(SeO3)2 (CaNi) and Na2Cu(SeO3)2·2H2O (NaCu) were obtained by a hydrothermal method. Both compounds crystallize in the triclinic system of space group P1, featuring a selenite-bridged one-dimensional (1D) spin-chain structure running along the a-axis. Magnetic measurements indicate that CaNi undergoes a long-range antiferromagnetic order (LRO) at TN = ∼3.8 K, while NaCu does not exhibit a LRO down to 2 K but the onset of a short-range correlation at TM = ∼30 K. The intrachain exchange coupling J/kB = -2.59 K for CaNi and J/kB = -47.13 K for NaCu can be estimated by a fit using the 1D spin-chain model. The thermogravimetric analyses show that both compounds are stable below 130 °C. The UV-vis diffuse reflectance spectra indicate that the band gaps of CaNi and NaCu are 4.38 eV and 3.18 eV, respectively.

We have successfully synthesized a new transition metal tellurate compound K2Cu2(Te2O5)(TeO3)2·2H2O. The compound crystallizes in the monoclinic crystal system with space group P21/c; the Te coordi...

The Cu2+-based breathing kagome material Pb(OF)Cu3(SeO3)2(NO3) with both corner-sharing and edge-sharing has been synthesized. Magnetic measurements suggest ferromagnetic interactions inside the layers and antiferromagnetic interactions between the neighboring layers, leading to an antiferromagnetic ground state with a field-induced spin-flip transition at low temperature.

Enhancement of permeability and the retention effect is one of the main pathways for the accumulation of nanomaterials in tumor sites, but poor cellular internalization and rapid clearance of nanomaterials always hamper the efficacy of imaging diagnosis and treatment. With the consideration of both high tumor accumulation and cellular internalization, positively charged nanomaterials can adhere to the tumor cell membrane by an electrostatic force, which is conducive to cellular internalization, but they are easily recognized and cleared during blood circulation. However, negatively charged nanomaterials show an enhanced stealth-like effect and possess a long blood circulation time, which is conducive to tumor accumulation. Therefore, in this work, on the basis of the shielding effect of citrate ions to positive charge and the protonation under an acidic tumor microenvironment, pH-sensitive sodium citrate-modified polyaniline nanoshuttles (NSs) with negative charge during blood circulation but positive charge in tumor sites are designed. With this hierarchical targeting strategy, the blood circulation half-life increases from 4.35 to 7.33 h, and the retention rate of NSs in tumors increases from 5.29 to 8.57% ID/g. Because the retention rate of NSs is increased, the magnetic resonance imaging resolution and signal intensity are significantly improved. A synergistic treatment of tumors is further achieved by means of photothermal therapy with laser irradiation and chemotherapy via heat-stimulated drug release.

Light-cross-linked small-molecule micelles with enediyne units are designed for developing efficient drug-delivery systems. Gemcitabine (GEM) is chosen as a model hydrophilic drug and tethered with a maleimide-based enediyne (EDY) as a hydrophobic tail in the preparation of amphiphilic EDY-GEM. The stable micellar particles are obtained by cross-linking the enediyne moieties via photoinduced Bergman cyclization polymerization in aqueous media. The light-cross-linked spherical micelles with a size of 80 nm are characterized with dynamic light scattering and electron microscopy, showing robust micellar stability, bright fluorescent emission due to their intrinsic conjugated structure, and potential passive tumor-targeting ability through the enhanced permeability and retention effect. The drug-loaded micelles, as an example of light-cross-linked small-molecule micelle-based drug-delivery system, exhibit high drug-loading contents (50%) and greatly improved cytotoxicity toward A549 cells (decreasing the IC50 value of Gemcitabine by 10 times), thanks to the greatly increased cellular uptake of the drug-loaded micelles as confirmed by confocal laser scanning microscopy. The light-cross-linked enediyne-based small-molecule micelles system therefore provides a simple yet efficient drug-delivery platform for cancer chemotherapy.

Single crystals of Fe2(TeO3)2(SO4)·3H2O with an alternating spin-chain structure are successfully grown by a hydrothermal method. Magnetic and heat capacity measurements show that this compound possesses a short-range antiferromagetic order at ~55 K and a long-range antiferromagetic order at 32.5 K. A large magnetic anisotropy with magnetization easy c-axis is observed, in which a weak ferromagnetic component is observed along the a- and b-axes, while a spin flop transition is observed at applied field along the c-axis. Also, the magnetic anisotropy energy at 2 K is estimated to be 4.78(3) × 108 ergs/cm3. Such magnetic anisotropy may be due to a strong nonsymmetric distortion in the FeO6 octahedra.

Three dodecanuclear 3d–4f coordination clusters, [CrIII6LnIII6(μ3-OH)8(tbdea)6(C6H5COO)16]·2H2O (Ln = Dy (1), Y (2)) and [CoIII6DyIII6(μ3-OH)8(nbdea)6(m-CH3C6H4COO)16]·2H2O·2CH3CN (3), have been synthesized under solvothermal conditions and characterized. Single-crystal X-ray diffraction analysis revealed that all three compounds possess an analogous {MIII6LnIII6} core (M = Cr, Co; Ln = Dy, Y) and dc magnetic susceptibility studies indicated that the magnetic exchange couplings between DyIII ions are dominant antiferromagnetic, while the CrIII–DyIII interactions are weakly ferromagnetic. Furthermore, the ac magnetic susceptibility measurements showed that both CrIII6DyIII6 compound 1 and CoIIi6DyIII6 compound 3 containing highly anisotropic DyIII ions displayed single-molecule magnetic (SMM) behavior with the energy barrier Ueff increasing from 12.8 K (for 1) to 20.8 K (for 3), indicating that weak 3d–4f exchange couplings enhance the QTM and reduce the energy barrier.

Carbon nanotube (CNT) macroscopic assembly, as a promising candidate for the protective and anti-collision materials, has attracted lots of researchers to explore its mechanical behavior under different loading rates. In this paper, the loading-rate dependent mechanical behavior of CNT film and its composite with bismaleimide (BMI) matrix is investigated. The pristine CNT film shows decreased tensile strength by 33.8% when the loading rate increases from 0.05 mm/min to 40 mm/min. An obvious necking extending phenomenon is observed in the CNT film during the tensile test under lower tensile rates, e.g. 0.05 mm/min and 0.5 mm/min. However, the random composite film and the oriented composite film both display increased tensile strength, by 58.2% and 35.7% respectively, with the increasing loading rate from 0.05 mm/min to 40 mm/min. The different loading-rate dependence of tensile behavior is ascribed to the different tensile-induced motions of CNTs and CNT bundles in composite film. Moreover, strain rate sensitivity coefficients of different film are calculated according to a simplified Johnson-Cook model. The results suggest that the pristine CNT film with the strain rate sensitivity coefficient of −0.0941 has a high loading-rate sensitivity, meanwhile polymer infiltration and oriented alignment can weaken the loading-rate sensitivity of CNT film. Keywords: Carbon nanotube film, Polymer composite, Tensile properties, Loading-rate sensitivity

Two new potassium ytterbium sulfates KYb(SO4)2·H2O and KYb(SO4)F2 have been obtained by a conventional hydrothermal method, which are found to crystallize in the monoclinic system with space group P21/n and P21/m, respectively. KYb(SO4)2·H2O features a three-dimensional open framework built by isolated YbO4 polyhedra and SO4 tetrahedra, while KYb(SO4)F2 exhibits a zigzag-chain structure built by YbO4F4 polyhedra running along [010] direction. Magnetic measurements indicate that both of two compounds display a paramagnetic behavior down to 2 ​K with a dominant antiferromagnetic interactions between ytterbium ions. TGA and temperature-dependent PXRD measurements verify the excellent thermal stability of their frameworks. Solid-state UV–vis–NIR diffuse reflectance spectra show that they have wide optical band gaps of 4.95 ​eV and 5.36 ​eV, respectively.

A new 3d-4f heterometallic selenite chloride FeNd2(SeO3)4Cl has been successfully synthesized by a conventional hydrothermal method. The compound crystallizes in the monoclinic space group C2/C, in which the Fe-layers show an irregular triangle motif and the Nd-layers feature a distorted Shastry-Sutherland lattice. Magnetic measurements show that the compound does not show any peaks of magnetic susceptibility but shows a sharp peak in the heat capacity data under different fields, indicating a possible “hidden antiferromagnetic ordering behavior” in the system. Also, a field-induced magnetic transition is obtained in the magnetization curve.

The resistance of polycrystalline divalent-ion-doped LaMnO 3 has been shown to be highly sensitive to low magnetic fields. To enable direct study of the properties of isolated grain boundaries, we developed a new method to form artificial boundaries in manganite thin films. Metal slits about 70 nm in width were printed by 30 KV focused Ga ion beam nanolithography on a 4 μ m La 2 / 3 Sr 1 / 3 MnO 3 bridge, and the materials in these slits were then irradiated by accelerated H 2 + ions. Using this method, magnetoresistance (MR) > 8 % and > 16 % were, respectively, obtained at 150 and at 10 K in a magnetic field of 1 T. This technique is very promising in terms of its simplicity and flexibility of fabrication and has the potential for high-density integration.

A large magnetic-field-induced strain (MFIS) of 1150 ppm has been obtained in textured Ni50.5Mn24Ga25.5 polycrystal prepared by vertical zone melting unidirectional solidification. X-ray diffraction measurements of the cubic structure reveal that the preferential orientation along the growth direction is (220). Expansion and shrinkage phenomenon upon the martensitic transition has been observed at 223 K (martensitic transition temperature M-s), indicating the existence of a preferential orientation of martensitic variants to minimize elastic energy. This martensitic transition strain can be enhanced six times, up to 1.5% shrinkage with a bias magnetic field of 1.5 T. (C) 2003 Elsevier B.V. All rights reserved.

Bonding of Al–Pb alloy strips and hot-dipped Al or Al–2% Si steel sheets were carried out using hot rolling. The effects of addition of 2% Si to the bath, the dipping time, the thickness of the intermetallic layers and the fraction of the blank interfaces on the bonding strength are investigated. In all case, two different kinds of interfaces are produced, hot-dip aluminized steel sheets and Al–Pb alloy strips are bonded through the mechanism of blank and block interface bonding. The total bonding strength depends mainly on that of blank interface and the fraction of the blank interfaces. The bonding strength of blank interfaces is four or five times as high as that of block interfaces. There is a linear relationship between the bonding strength and the fraction of the blank interfaces. An EPMA linescan across the blank interface reveals that higher concentration of aluminum in the transition layer of Fe and Al formed in the blank interface region for a dipped specimen of Al–2% Si than that for a dipped specimen of Al.

Ni80Fe20/Mo magnetic multilayers with a repeat length of 3.4 nm have been fabricated using magnetron sputtering. The interdiffusion coefficient D was determined by measuring the intensity of the X-ray satellite peak arising from the modulation as a function of annealing time. As annealing temperature is below 483 K, the interdiffusion was found to be relatively slow (D < 8.88 x 10(-25) m(2)/s); in that the Ni80Fe20/Mo multilayers have a strong resistance to atomic interdiffusion. The temperature dependence of interdiffusion in the range 343-683 K is described by D = 4.02 x 10(-22) exp(- 0.26 eV/kT) m(2) s(-1). Compared with the extrapolation of published higher temperature data, the interdiffusion at a temperature of 633 K is found to be more rapid, which is suggested to result from moving grain boundaries and coherency strains in the multilayers. (C) 1998 Elsevier Science B.V. All rights reserved.