Tuneable magnetic properties of hydrothermally synthesised core/shell CoFe2O4/NiFe2O4 and NiFe2O4/CoFe2O4 nanoparticles

The aim of this study was to prepare a novel targeting nano drug delivery system of 2-methoxyestradiol (2-ME) based on the folic acid-modified bovine serum albumin, in order to improve the clinical application disadvantages and antitumor effect of 2-ME. In this study, 2-methoxyestradiol-loaded albumin nanoparticles (2-ME-BSANPs) were prepared by desolvation method, and then the activated folic acid was conjugated to 2-ME-BSANPs by covalent attachment (2-ME-FA-BSANPs). The size and zeta potential of 2-ME-FA-BSANPs were about 208.8 ± 5.1 nm and ?32.70 ± 1.01 mV, respectively. 2-ME loading efficiency and loading amount of the nanoparticles were 80.49 ± 3.80 and 10.25 ± 1.59 %, respectively. SEM images indicated that 2-ME-FA-BSANPs were of a round shape, similar uniform size, and smooth surface. Studies on drug release indicated that 2-ME-FA-BSANPs had the properties of sustained and controlled release, which provided them with the ability to fight continually against cancer cells. Internalization analysis demonstrated that 2-ME-FA-BSANPs-targeting drug delivery system could get efficiently transferred into the cells through the folic acid-mediated endocytosis, leading to higher apoptosis and affording higher antitumor efficacy against SMMC-7721 cells in vitro compared with 2-ME alone. Furthermore, the cell-cycle arrest of 2-ME-FA-BSANPs on the SMMC-7721 cells occurred at G2/M phase, and 2-ME-FA-BSANPs did not change the inhibition of the tumor mechanisms of 2-ME. Based on these results, it was concluded that albumin nanoparticles could be the promising nano carrier for 2-ME, and 2-ME-FA-BSANPs-targeting drug delivery system may be promising candidate for providing high treatment efficacy with minimal side effects in future cancer therapy.     

Research into teacher knowledge: a stimulus for development in mathematics teacher education practice

In this paper, we document some developments in teacher education practice at one university, brought about by reflection on research into mathematics teacher knowledge. The authors are three members of the Cambridge-based research team who developed the Knowledge Quartet (KQ), a theory of mathematics teacher knowledge, with a focus on classroom situations in which this knowledge is applied. At the same time as being researchers, the authors were elementary mathematics teacher education instructors. They found that the KQ research brought about new awareness of the importance of some components of mathematics didactics, as well as providing new tools for undertaking some aspects of their teacher educator role. The paper explores some of these awarenesses and tools in detail.     

Contributions to the 37Ar background by research reactor operations

Radioargon has been identified as a useful nuclide for verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty. Use of ³⁷Ar to identify a nuclear explosion requires quantification of contributions to the ³⁷Ar background at a potential measurement site. A method of estimating ³⁷Ar release activities using isotopes of radioxenon and radioargon has been developed in this paper. Numerical solutions to the system of equations describing air-activation in a reactor were used to determine ratios of release activities for ¹³⁵Xe/¹³³Xe, ^133mXe/^131mXe, and ³⁷Ar /⁴¹Ar as function of irradiation time and off-gas residence time prior to measurement and release. Published radioactive noble gas effluent data for the High Flux Isotope Reactor, HFIR (ORNL) from the year 1996 to 2010 were compiled as a test data set to predict the ³⁷Ar release on a yearly basis. An average ³⁷Ar release rate of 1.86 × 10¹⁰ Bq per year was calculated. The estimated release rate was used as a source term for atmospheric transport to run a test case for ³⁷Ar release over a typical HFIR operation cycle. Results showed that ground-level concentrations of ³⁷Ar did not exceed the minimum detectable concentration for a ³⁷Ar field measurement system beyond the immediate vicinity of the release point.     

Determination of the Mo surface environment of Mo/TiO2 catalysts by EXAFS,XANES and PCA

The local structure of oxidic Mo/TiO₂ catalysts (0.5 to 13.5 wt.% Mo) has been studied using EXAFS and XANES. Both EXAFS and XANES results suggest that the Mo surface phase is octahedrally coordinated for all Mo loadings. The EXAFS results were also examined using principal component analysis (PCA) to determine the number of Mo species present on the Mo/TiO₂ catalysts. Results from PCA of the Mo EXAFS spectra suggested the presence of three Mo species: two surface species and bulk MoO₃.     

Trilocal structures. IV. momentum-dependent tree functions

Enlarging the set of tree functions to include those which depend on the momentum vector has the effect of introducing new families and subfamilies of functions. Four auxiliary conditions are used in the generation of these functions. These auxiliary conditions introduce, as eigenvalues, four parameters in terms of which the coefficients of the momentum-dependent functions can then be expressed as linear combinations of the 16 leading coefficients. These 16 are all rest-system coefficients. Thus the momentum-dependent part of the expansion is expressible in terms of the rest-system portion, using only these four parameters.     

Pesticide residue analysis of a dietary ingredient by gas chromatography/selected-ion monitoring mass spectrometry using neutral alumina solid-phase extraction cleanup

A sample cleanup procedure has been developed to remove coextractives that interfere with pesticide residue analysis of a dietary ingredient (Product B), an extract consisting of Scutellaria baicalensis and Acacia catechu. Samples were extracted using 1% acetic acid in acetonitrile, followed by solid-phase extraction and analysis by capillary gas chromatography with mass spectrometry in the selective-ion monitoring mode. Neutral alumina (alumina N) was found to be the most effective sorbent to remove coextractives from Product B; other materials that were tested but failed to remove interference were graphitized carbon black/primary-secondary amine (PSA), octadecylsilane (C18), Florisil, Oasis MCX, and strong anion exchange-PSA. The method was specifically developed for Product B, which was spiked with 41 organochlorine and organophosphorus pesticides, and resulted in the recovery of 80 to 120% at U.S. Pharmacopeia limits (0.06 to 4 microg/g) for the majority of the pesticides.     

Structural, electrochemical, and spectroscopic characterization of a redox pair of sulfite-based polyoxotungstates: alpha-[W18O54(SO3)2]4- and alpha-[W18O54(SO3)2]5-

The synthesis, isolation, and structural characterization of the fully oxidized sulfite-based polyoxotungstate cluster (Pr4N)4{alpha-[W18O54(SO3)2]}.2CH3CN and the one-electron reduced form (Pr4N)5{alpha-[W18O54(SO3)2]}.2CH3CN has been achieved. alpha-[W18O54(SO3)2]5- was obtained as a Pr4N+ salt by reducing the "Trojan Horse" [W18O56(SO3)2(H2O)2]8- cluster via a template orientation transformation. Acetonitrile solutions of pure alpha-[W18O54(SO3)2]5- also were prepared electrochemically by one-electron bulk reductive electrolysis of alpha-[W18O54(SO3)2]4-. Cyclic voltammetry of alpha-[W18O54(SO3)2]4- and alpha-[W18O54(SO3)2]5- in CH3CN (0.1 M Hx4NClO4) produces evidence for an extensive series of reversible one-electron redox processes, that are associated with the tungsten-oxo framework of the polyoxometalate cluster. Hydrodynamic voltammograms in CH3CN exhibit the expected sign and magnitude of the steady-state limiting current values for the alpha-[W18O54(SO3)2]4-/5-/6- series and confirm the existence of a stable one-electron reduced species, alpha-[W18O54(SO3)2]5-. Employment of the Randles-Sevcik (cyclic voltammetry) and Levich (rotating disk electrode) equations at a glassy carbon electrode (d=3 mm) enable diffusion coefficient values of 3.7 and 3.8x10(-6) cm2 s-1 to be obtained for alpha-[W18O54(SO3)2]4- and alpha-[W18O54(SO3)2]5-, respectively. The tungsten polyoxometalates are highly photoactive, since measurable photocurrents and color changes are detected for both species upon irradiation with white light. EPR spectra obtained from both acetonitrile solution and solid samples, down to temperatures as low as 2.3 K, of the chemically and electrochemically prepared one-electron reduced species provided evidence that the unpaired electron in alpha-[W18O54(SO3)2]5- is delocalized over a number of atoms in the polyoxometalate structure, even at very low temperatures.     

Prediction of clearing effects in far-field blast loading of finite targets

It is well known that when a blast wave strikes the face of a target, the duration of the loading, and hence the total impulse imparted to the target may be influenced by the propagation of a rarefaction, or “clearing” wave along the loaded face of the target adjacent to free edges. Simple methods of predicting the effect of clearing on reducing the blast loading impulse have been available for many years, but recent studies have questioned the accuracy and physical basis of these approaches. Consequently, several authors have used numerical modelling and/or experimental techniques to determine empirical predictive methods for the clearing effect. In fact, the problem had been addressed more than 50 years ago in a study which appears to have been since overlooked by the blast research fraternity. This article presents the results of that earlier study, and provides experimental validation. The analytical predictions are very simple to determine, and are shown to be in excellent agreement with experimental results.     

Awakening of a ferrous complex's electronic spin in an aqueous solution induced by a chemical stimulus

A low-spin, macrocyclic iron(II) complex in an aqueous solution responds to the addition of a chemical reactant (dithionite) by transformation into a high-spin complex, detectable by measurement of the longitudinal relaxation time (T(1)) of surrounding water hydrogen nuclear spins. The initial compound does not modify T(1) of pure water at concentrations as high as 4 mM. The response is pH-dependent, and the complex is robust at a variety of conditions.     

Nanosized Shape‐Changing Colloids from Liquid Crystalline Elastomers

A method to prepare shape‐changing nanospheres from liquid crystalline elastomers is reported. The nanosized colloids are prepared by a miniemulsion process. During this process, colloids are prepared from a liquid crystalline (LC) main‐chain polyester and subsequently crosslinked into a nanometer‐sized LC elastomer. The ability of these LC elastomers to change their shape at the phase transition temperature from the smectic A to the isotropic phase was detected by temperature‐dependent transmission electron microscopy. The phase transition‐induced shape change leads to strongly shape anisotropic nanosized elastomer particles.