Hydration of the Calcium Dication: Direct Evidence for Second Shell Formation from Infrared Spectroscopy

Infrared laser action spectroscopy in a Fourier‐transform ion cyclotron resonance mass spectrometer is used in conjunction with ab initio calculations to investigate doubly charged, hydrated clusters of calcium formed by electrospray ionization. Six water molecules coordinate directly to the calcium dication, whereas the seventh water molecule is incorporated into a second solvation shell. Spectral features indicate the presence of multiple structures of Ca(H₂O)₇²⁺ in which outer‐shell water molecules accept either one (single acceptor) or two (double acceptor) hydrogen bonds from inner‐shell water molecules. Double‐acceptor water molecules are predominately observed in the second solvent shells of clusters containing eight or nine water molecules. Increased hydration results in spectroscopic signatures consistent with additional second‐shell water molecules, particularly the appearance of inner‐shell water molecules that donate two hydrogen bonds (double donor) to the second solvent shell. This is the first reported use of infrared spectroscopy to investigate shell structure of a hydrated multiply charged cation in the gas phase and illustrates the effectiveness of this method to probe the structures of hydrated ions.     

Direct determination of 4-hydroxy-3-methoxyphenylacetic (homovanillic) acid in urine by high-performance liquid chromatography with amperometric detection

The improvement of high-performance liquid chromatographic analysis with electrochemical detection for urinary homovanillic acid is described. The method permits the chromatographic resolution of authentic homovanillic acid from coeluting interfering compounds in human and nonhuman primate, and rat urine. The electrochemically derived results are compared with post-column derivatized fluorescence results, and quality-control checks necessary to maintain assay precision in automated analysis are described.     

Interfacial propulsion by directional adhesion

The rough integument of water-walking arthropods is well-known to be responsible for their water-repellency [1], [2], [3] and [4]; however, water-repellent surfaces generally experience reduced traction at an air-water interface [5], [6], [7] and [8]. A conundrum then arises as to how such creatures generate significant propulsive forces while retaining their water-repellency. We here demonstrate through a series of experiments that they do so by virtue of the detailed form of their integument; specifically, their tilted, flexible hairs interact with the free surface to generate directionally anisotropic adhesive forces that facilitate locomotion. We thus provide new rationale for the fundamental topological difference in the roughness on plants and water-walking arthropods, and suggest new directions for the design and fabrication of unidirectional superhydrophobic surfaces.     

The Average Range Characterization of the Radon–Nikodym Property

A characterization of Banach spaces possessing the Radon—Nikodym property is given in terms of the average range of additive interval functions. We prove that a Banach space X has the RNP if and only if each X-valued additive interval function possessing absolutely continuous McShane (or Henstock) variational measure has nonempty average range almost everywhere on [0, 1].     

X-ray, Mössbauer, and dielectric studies of the Co1 − x Ni x Cr2O4 ceramic system

The temperature dependences of the dielectric constant, ?(T), dielectric loss tangent, tanδ(T), and thermostimulated depolarization currents of (Co_{1 ? x} Ni _x )Cr₂O₄:y ⁵⁷Fe₂O₃ samples with 0.2 ≤ x ≤ 0.6 and 0.01 ≤ y ≤ 0.04 exhibit anomalies at temperatures of T ₁ ≈ 220 K and T ₂ ≈ 240 K that indicate a transition to an ordered ferroelectric state at temperatures below T ₂. Also observed at the same temperatures are abrupt changes in the isomer shift and quadrupole splitting for two Mössbauer spectral doublets of a sample with x = 0.2.     

Low-frequency magnetoelectric effect in a Galfenol-PZT planar composite structure

The forward and inverse magnetoelectric (ME) effects are experimentally studied in a two-layer planar structure containing mechanically coupled Galfenol and PZT plates. The process of production of polycrystalline Galfenol plates and their magnetic and magnetostriction characteristics are described. For the forward ME conversion, the dependences of the amplitude of the voltage generated by the structure on the magnitude and orientation of a dc magnetic field and the frequency and amplitude of a modulating magnetic field are measured. For the inverse ME conversion, the dependences of the amplitude of the change in the magnetic induction of the structure on the dc magnetic field and the frequency of an ac electric field applied to the structure are measured. The efficiencies of the forward and inverse ME conversion are estimated for the case of low-frequency field modulation and under conditions of the resonance excitation of bending and longitudinal mechanical vibrations in the structure.     

Development of elementary teachers' science,technology, engineering,arts, and mathematics planning practices

The purpose of this instrumental case study was to understand elementary teachers' planning of Science, Technology, Engineering, Arts, and Mathematics (STEAM) curriculum during a two-year professional development experience. This research was guided by the following question: What planning practices developed or changed during a professional development experience? Analysis of 25 teachers' planning documents indicated growth in the following areas: (a) tighter alignment to fewer standards, (b) more meaningful integration and broader definitions of arts and technology, and (c) increased use of formative assessment but persistent difficulties in summatively assessing the multiple disciplines of STEAM. The growth in teachers' STEAM instruction from the beginning to the end of this two-year professional development was important in building our understanding of what constitutes sound design of STEAM inquiries.     

A direct-to-biology high-throughput chemistry approach to reactive fragment screening

Methods for rapid identification of chemical tools are essential for the validation of emerging targets and to provide medicinal chemistry starting points for the development of new medicines. Here, we report a screening platform that combines ‘direct-to-biology’ high-throughput chemistry (D2B-HTC) with photoreactive fragments. The platform enabled the rapid synthesis of >1000 PhotoAffinity Bits (HTC-PhABits) in 384-well plates in 24 h and their subsequent screening as crude reaction products with a protein target without purification. Screening the HTC-PhABit library with carbonic anhydrase I (CAI) afforded 7 hits (0.7% hit rate), which were found to covalently crosslink in the Zn²⁺ binding pocket. A powerful advantage of the D2B-HTC screening platform is the ability to rapidly perform iterative design–make–test cycles, accelerating the development and optimisation of chemical tools and medicinal chemistry starting points with little investment of resource.

A photoreactive fragment screening platform employing direct-to-biology high-throughput chemistry (D2B-HTC) for the rapid iterative synthesis and screening of libraries of photoaffinity bits.     

Dielectric Response of Ceramic 16BiScO3–42PbMg1/3Nb2/3O3–42PbTiO3 Solid Solutions in an Electrical Field

Physics of the Solid State - Some results of studying the dielectric and electromechanical properties of ceramic 16BiScO3–42PbMg1/3Nb2/3O3–42PbTiO3 relaxor ferroelectric samples in...