Surfactant-assisted one-pot synthesis of superparamagnetic magnetite nanoparticle clusters with tunable cluster size and magnetic field sensitivity

Magnetic nanoparticles (MNPs) have many potential biomedical applications. Improvements in their magnetic properties and solubility are necessary for these applications to realize their full potential. In this study, MNPs in the form of raspberry-like magnetite (Fe(3)O(4)) nanoparticle clusters, consisting of tiny Fe(3)O(4) particles with a diameter of approximately 20 nm, were prepared under hydrothermal conditions at 200 °C in the presence of 3,4-dihydroxyhydroxysinnamic acid (DHCA). The primary particles were connected by DHCA molecules to form the clusters, which were well dispersed in water media because a COOH group from DHCA appeared on their surfaces. The cluster size could be tuned from 50 to 400 nm without changing the primary particle size by controlling the reaction time. Therefore, all prepared clusters displayed superparamagnetic properties at room temperature. In addition, the sensitivity of Fe(3)O(4) to an external magnetic field could also be controlled by the cluster size.     

Allergen diagnosis microarray with high-density immobilization capacity using diamond-like carbon-coated chips for profiling allergen-specific IgE and other immunoglobulins

The diagnosis of antibody-mediated allergic disorders is based on clinical findings, skin prick tests and detection of allergen-specific IgE in serum. Here, we present a new microarray technique of high-density antigen immobilization using carboxylated arms on the surface of a diamond-like carbon (DLC)-coated chip. High immobilization capacity of antigen on DLC chip at (0.94–7.82) × 10⁹ molecules mm⁻² allowed the analysis of allergen-specific immunoglobulins against not only purified proteins but also natural allergen extracts with wide assay dynamic range. The higher sensitivity of the allergen-specific IgE detection on DLC chip was observed for comparison with the UniCAP system: the DLC chip allowed lowering the limit of dilution rate in UniCAP system to further dilution at 4–8-fold. High correlations (ρ > 0.9–0.85) of allergen-specific IgE values determined by the DLC chip and UniCAP were found in most of 20 different allergens tested. The DLC chip was useful to determine allergen-induced antibodies of IgA, IgG, IgG1, and IgG4 in sera, apart from IgE, as well as secretory IgA in saliva against the same series of allergens on the chip in a minimal amount (1–2 μL) of sample.     

Structure-activity relationships of 1,3-benzoxazole-4-carbonitriles as novel antifungal agents with potent in vivo efficacy

A series of 1,3-benzoxazole-4-carbonitriles was synthesized and evaluated for its antifungal activity, solubility, and metabolic stability. Among those compounds, 4-cyano-N,N,5-trimethyl-7-[(3S)-3-methyl-3-(methylamino)pyrrolidin-1-yl]-6-phenyl-1,3-benzoxazole-2-carboxamide (16b) exhibited potent in vitro activity against Candida species, higher water solubility, and improved metabolic stability compared to lead compound 1. Compound 16b showed potent in vivo efficacy against mice Candida infection models and good bioavailability in rats.     

Effect of bubbles on turbulent kinetic energy transport in downward flow measured by time-resolved PTV

A time-resolved particle tracking velocimetry (PTV) system and a shape projection imaging system were used to investigate the turbulence modifications by bubbles in a downward bubbly flow. Two bubble sizes and three mean void fractions were tested at a Reynolds number of about 20,000. The strong modifications in the mean velocity, turbulent kinetic energy (TKE) budget, and velocity spectra are observed in the central region of the pipe that has a high local void fraction. In particular, kinetic energy production decreased, whereas the TKE dissipation rate increased. This suggests that the transfer of energy due to bubbles has a very large effect on the TKE budget. Moreover, velocity spectra reveal that the presence of bubbles modifies the length scales of turbulent eddies, which contain, transfer, and dissipate energy.     

Born-Oppenheimer breakdown and non-adiabatic lifetimes of rovibrational levels of D2 lying near the n = 2 dissociation limit: Experiment and theory

The singlet gerade states of the hydrogen molecule are strongly affected by the breakdown of the Born-Oppenheimer approximation. This leads to strong non-adiabatic coupling resulting in large changes of the energies and lifetimes of the quantum levels compared to the values obtained in the Born-Oppenheimer or even the adiabatic levels of approximation. The non-adiabatic calculations of Quadrelli, Dressler, and Wolniewicz (1990) [7] (hereinafter QDW) for the three highest vibrational levels (υ = 44, 45, and 46) of the EF ¹Σ_g⁺ state of D₂ predicted an enormous increase of the lifetimes upon excitation of just one quantum of rotational motion. However, although our experimental results for these levels just below the n = 2 dissociation limit do show a strong increase in lifetime, the non-adiabatic lifetimes calculated by QDW are longer than experiment by as much as three orders of magnitude. In their work on isotopomers of hydrogen QDW and Yu and Dressler (1994) [5] published extensive summary tables of ab initio non-adiabatic coupling data. We present a technique which allows us to use their summary data to calculate approximate non-adiabatic ab initio lifetimes. The results reconcile our observed lifetimes with the non-adiabatic coupling from those previous ab initio calculations and also provide a detailed quantitative and qualitative understanding of the unusual rotational dependence of the lifetimes of these very highly excited levels. We also test the current technique by calculating the lifetimes of other levels involved in interactions with these EF levels and by calculating the lifetimes of the EF υ = 33 level of H₂, for which no corresponding level exists in the Born-Oppenheimer or adiabatic approximations.     

The asymptotic formula in Waring’s problem for one square and seventeen fifth powers

Let R _k,s(n) denote the number of solutions of the equation \({n= x^2 + y_1^k + y_2^k + \cdots + y_s^k}\) in natural numbers x, y ₁, . . . , y _s . By a straightforward application of the circle method, an asymptotic formula for R _k,s(n) is obtained when k ≥ 3 and s ≥ 2^k–1 + 2. When k ≥ 6, work of Heath-Brown and Boklan is applied to establish the asymptotic formula under the milder constraint s ≥ 7 · 2^k–4 + 3. Although the principal conclusions provided by Heath-Brown and Boklan are not available for smaller values of k, some of the underlying ideas are still applicable for k = 5, and the main objective of this article is to establish an asymptotic formula for R _5,17(n) by this strategy.     

The effect of heat treatment on the performance of the Ni/(Zr-Sm oxide) catalysts for carbon dioxide methanation

The active catalysts for methane formation from the gas mixture of CO₂ + 4H₂ with almost 100% methane selectivity were prepared by reduction of the oxide mixture of NiO and ZrO₂ prepared by calcination of aqueous ZrO₂ sol with Sm(NO₃)₃ and Ni(NO₃)₂. The 50 at%Ni-50 at%(Zr-Sm oxide) catalyst consisting of 50 at%Ni-50 at%(Zr + Sm) with Zr/Sm = 5 calcined at 650 or 800 °C showed the highest activity for methanation. The active catalysts were Ni supported on tetragonal ZrO₂, and the activity for methanation increased by an increase in inclusion of Sm³⁺ ions substituting Zr⁴⁺ ions in the tetragonal ZrO₂ lattice as a result of an increase in calcination temperature. However, the increase in calcination temperature decreased BET surface area, metal dispersion and hydrogen uptake due to grain growth. Thus, the optimum calcination temperature existed.     

Application of carbon fibers to biomaterials: a new era of nano-level control of carbon fibers after 30-years of development

Carbon fibers are state-of-the-art materials with properties that include being light weight, high strength, and chemically stable, and are applied in various fields including aeronautical science and space science. Investigation of applications of carbon fibers to biomaterials was started 30 or more years ago, and various products have been developed. Because the latest technological progress has realized nano-level control of carbon fibers, applications to biomaterials have also progressed to the age of nano-size. Carbon fibers with diameters in the nano-scale (carbon nanofibers) dramatically improve the functions of conventional biomaterials and make the development of new composite materials possible. Carbon nanofibers also open possibilities for new applications in regenerative medicine and cancer treatment. The first three-dimensional constructions with carbon nanofibers have been realized, and it has been found that the materials could be used as excellent scaffolding for bone tissue regeneration. In this critical review, we summarize the history of carbon fiber application to the biomaterials and describe future perspectives in the new age of nano-level control of carbon fibers (122 references).     

Photocatalytic hydrogen generation from water with iron carbonyl phosphine complexes: improved water reduction catalysts and mechanistic insights

An extended study of a novel visible-light-driven water reduction system containing an iridium photosensitizer, an in situ iron(0) phosphine water reduction catalyst (WRC), and triethylamine as sacrificial reductant is described. The influences of solvent composition, ligand, ligand-to-metal ratio, and pH were studied. The use of monodentate phosphine ligands led to improved activity of the WRC. By applying a WRC generated in situ from Fe(3) (CO)(12) and tris[3,5-bis(trifluoromethyl)phenyl]phosphine (P[C(6)H(3)(CF(3))(2)](3), Fe(3)(CO)(12)/PR(3)=1:1.5), a catalyst turnover number of more than 1500 was obtained, which constitutes the highest activity reported for any Fe WRC. The maximum incident photon to hydrogen efficiency obtained was 13.4% (440 nm). It is demonstrated that the evolved H(2) flow (0.23 mmol H(2) h(-1) mg(-1) Fe(3)(CO)(12)) is sufficient to be used in polymer electrolyte membrane fuel cells, which generate electricity directly from water with visible light. Mechanistic studies by NMR spectroscopy, in situ IR spectroscopy, and DFT calculations allow for an improved understanding of the mechanism. With respect to the Fe WRC, the complex [HNEt(3)](+)[HFe(3)(CO)(11)](-) was identified as the key intermediate during the catalytic cycle, which led to light-driven hydrogen generation from water.