Structural characteristics of different types of nanoparticles synthesised in mesomorphic metal alkanoates

The class of thermotropic ionic liquid crystals (LCs) of the metal alkanoates possesses a number of unique properties, such as intrinsic ionic conductivity, high dissolving ability and ability to form time-stable mesomorphic glasses. These ionic LCs can be used as nanoreactors for the synthesis and stabilisation of different types of nanoparticles (NPs). Thus, some semiconductors, metals and core/shell NPs were chemically synthesised in the thermotropic ionic liquid crystalline phase (smectic A) of the cadmium octanoate (CdC₈) and of the cobalt octanoate (CoC₈). By applying the scanning electron microscopy, the cadmium and cobalt octanoate composites containing CdS, Au, Ag and core/shell Au/CdS NPs have been studied. NPs’ sizes and dispersion distribution of the NPs’ size in the nanocomposites have been obtained.     

Dielectrophoretic trapping of nanoparticles with an electrokinetic nanoprobe

A high aspect ratio 3D electrokinetic nanoprobe is used to trap polystyrene particles (200 nm), gold nanoshells (120 nm), and gold nanoparticles (mean diameter 35 nm) at low voltages (<1 V_rms). The nanoprobe is fabricated using room temperature self‐assembly methods, without the need for nanoresolution lithography. The nanoprobe (150–500 nm in diameter, 2–150 μm in length) is mounted on the end of a glass micropipette, enabling user‐specified positioning. The nanoprobe is one electrode within a point‐and‐plate configuration, with an indium–tin oxide cover slip serving as the planar electrode. The 3D structure of the nanoprobe enhances dielectrophoretic capture; further, electro‐hydrodynamic flow enhances trapping, increasing the effective trapping region. Numerical simulations show low heating (1 K), even in biological media of moderate conductivity (1 S/m).     

Ultra-incompressible Ternary Diborides Re_（0.5）Ir_（0.5）B_2,Re_（0.5）Tc_（0.5）B_2,Os_（0.5）W_（0.5）B_2 and Os_（0.5）Ru_（0.5）B_2：Density Functional Calculation

In this paper, density functional computations have been applied to the structural, elastic and electronic properties of ternary transition metal diborides Re0.5Ir0.5B2, Re0.5Tc0.5B2, Os0.5W0.5B2 and Os0.5Ru0.5B2 in hexagonal (P63/mmc) and orthorhombic (Pmmn) structures with both local density approximation and generalized gradient approximation. LDA gives smaller lattice parameters and larger elastic moduli than GGA. Both results show that the hexagonal ones are more stable than orthorhombic ones except Os0.5Ru0.5B2. Moreover, the hexagonal structure has superior elastic property than orthorhombic one. Generally speaking, the calculated elastic moduli of Re0.5Ir0.5B2 and Os0.5Ru0.5B2 are smaller than those values of Re0.5Tc0.5B2 and Os0.5W0.5B2 within the same structure because of the filling of antibonding states. The relativistic effects result in weaker bonds of Tc-B (Ru-B) than those of Re-B (Os-B). All the diborides are ultra-incompressible. Re0.5Tc0.5B2 has the largest shear modulus and it is a promising superhard diboride like Os0.5W0.5B2. The elastic properties are in high correlation with the bond strength. The shear moduli are more sensitive than the bulk moduli to the bond strength.     

Using the outer coordination sphere to tune the strength of metal extractants

A series of 3-substituted salicylaldoximes has been used to demonstrate the importance of outer-sphere interactions on the efficacy of solvent extractants that are used to produce approximately one-quarter of the world's copper. The distribution coefficient for extraction of copper by 5-tert-butyl-3-X-salicylaldoximes (X = H, Me, (t)Bu, NO(2), Cl, Br, OMe) varies by more than two orders of magnitude. X-ray structure determinations of preorganized free ligand dimers (10 new structures are reported) indicate that substituents with a hydrogen-bond acceptor atom attached to the 3-carbon atom, ortho to the phenolic oxygen, buttress the intermolecular hydrogen bond from the oximic proton. Density functional theory calculations demonstrate that this hydrogen-bond buttressing is maintained in copper(II) complexes and contributes significantly to their relative stabilities in energy-minimized gas-phase structures. A remarkable correlation between the order of the calculated enthalpies of formation of the copper complexes in the gas phase and the observed strength of the ligands as copper solvent extractants is ascribed to the low solvation energies of species in the water-immiscible phase and/or the similarities of the solvation enthalpies of the preorganized ligand dimers and their copper(II) complexes.     

Pd-catalyzed Negishi coupling of pyrazole triflates with alkyl zinc halides

A mild, functional group tolerant palladium-catalyzed Negishi coupling of pyrazole triflates and nonaflates with alkyl, benzyl, and aryl zinc halides has been developed. It allows quick access to 3-substituted pyrazole analogs at late stage via common synthetic intermediates.     

Quantification of total and free carnitine in human plasma by hydrophilic interaction liquid chromatography tandem mass spectrometry

Carnitine is an endogenous quaternary amine whose primary function is to shuttle long chain fatty acids to the mitochondrial matrix, where they subsequently undergo beta oxidation. Accurate quantification of total and free carnitine is essential for the accurate diagnosis of a number of inborn errors of metabolism, including disorders of fatty acid oxidation as well as various organic acidurias. Early methods for carnitine measurement were enzyme based. Recently, liquid chromatography tandem mass spectrometry has become the method of choice for carnitine measurement. Typically, carnitine is derivitized to from a butyl ester, thus improving its ionization and retention characteristics. A potential problem with this approach is that the acidic conditions used to carry out the reaction may hydrolyze other acyl esters, resulting in ex-vivo artifacts. Consequently, we developed a hydrophobic interaction chromatography (HILIC) tandem mass spectrometry method for the quantification of carnitine. The use of HILIC allows for the derivitization step to be circumvented, while still allowing for favorable chromatographic performance. The method was shown to be accurate, precise, and robust.     

Assembly of the first fullerene-type metal-organic frameworks using a planar five-fold coordination node

Pump up the volume: Slow crystallization of Na[C(5) (CN)(5) ], the unsolvated sodium salt of pentacyanocyclopentadienide, gives the first example of an anionic coordination network based on metal-fullerene units. The structure of this network is closely related to a type?I gas clathrate in which around 66?% of the unit cell volume is occupied by solvent molecules.     

Quantification of branched-chain amino acids in blood spots and plasma by liquid chromatography tandem mass spectrometry for the diagnosis of maple syrup urine disease

Individuals with maple syrup urine disease (MSUD) have an inherited metabolic disorder resulting in a deficiency in the branched-chain keto-acid dehydrogenase complex. As a result, these individuals have elevated concentrations of the branched-chain amino acids valine, isoluecine, allo-isoleucine, and leucine. MSUD presents in the first few days of life and progression may lead to irreversible intellectual disability, coma, cerebral edema, and death. However, early diagnosis and intervention can mitigate or eliminate many of the potential adverse effects. Consequently, it is important to develop techniques to screen for MSUD. We have developed an LC-MS/MS assay for the diagnosis of MSUD. The method is amenable to high-throughput formats due to the minimal sample prep required. The assay was shown to be robust, precise, and accurate. Finally, we identified and addressed some of the problems associated with working with bloodspots and implemented satisfactory approaches to overcoming these problems.     

Fluid forces on a very low Reynolds number airfoil and their prediction

This paper presents the measurements of mean and fluctuating forces on an NACA0012 airfoil over a large range of angle (α) of attack (0-90°) and low to small chord Reynolds numbers (Re_c), 5.3 × 10³-5.1 × 10⁴, which is of both fundamental and practical importance. The forces, measured using a load cell, display good agreement with the estimate from the LDA-measured cross-flow distributions of velocities in the wake based on the momentum conservation. The dependence of the forces on both α and Re_c is determined and discussed in detail. It has been found that the stall of an airfoil, characterized by a drop in the lift force and a jump in the drag force, occurs at Re_c ? 1.05 × 10⁴ but is absent at Re_c = 5.3 × 10³. A theoretical analysis is developed to predict and explain the observed dependence of the mean lift and drag on α.     

Dietary supplement laboratory quality assurance program: the first five exercises

The National Institute of Standards and Technology (NIST) has established a Dietary Supplement Laboratory Quality Assurance Program (DSQAP) in collaboration with the National Institutes of Health Office of Dietary Supplements. Program participants measure concentrations of active and/or marker compounds as well as nutritional and toxic elements in food and dietary supplements distributed by NIST. Data are compiled at NIST, where they are analyzed for accuracy relative to reference values and concordance among the participants. Performance reports and certificates of completion are provided to participants, which can be used to demonstrate compliance with current Good Manufacturing Practices as promulgated by the U.S. Food and Drug Administration. The DSQAP has conducted five exercises to date, with total participation including more than 75 different laboratories and many more individual analysts.