Periodically kicked hard oscillators

A model of a hard oscillator with analytic solution is presented. Its behavior under periodic kicking, for which a closed form stroboscopic map can be obtained, is studied. It is shown that the general structure of such an oscillator includes four distinct regions; the outer two regions correspond to very small or very large amplitude of the external force and match the corresponding regions in soft oscillators (invertible degree one and degree zero circle maps, respectively). There are two new regions for intermediate amplitude of the forcing. Region 3 corresponds to moderate high forcing, and is intrinsic to hard oscillators; it is characterized by discontinuous circle maps with a flat segment. Region 2 (low moderate forcing) has a certain resemblance to a similar region in soft oscillators (noninvertible degree one circle maps); however, the limit set of the dynamics in this region is not a circle, but a branched manifold, obtained as the tangent union of a circle and an interval; the topological structure of this object is generated by the finite size of the repelling set, and is therefore also intrinsic to hard oscillators.     

Structural, Spectroscopic, and Thermal Behaviour of Bis-(thiosaccharinate)-aqua-cadmium(II)

Summary.  The crystal structure of the title complex, [Cd(tsac)₂(H₂O)], has been determined by single crystal X-ray diffraction methods. It crystallizes in the monoclinic space group C2/c (a = 12.236(3), b = 8.919(3), c = 16.655(3) ?, β = 96.18(2)°, Z = 4). The molecular structure was solved from 1705 independent reflections with I > σ(I) and refined to R ₁ = 0.0489. Infrared and Raman spectra of the complex were recorded and are briefly discussed. Its thermal behaviour was investigated by thermogravimetry and differential thermal analysis. Received December 18, 2000. Accepted February 19, 2001     

Crystal Chemistry of the Saccharinato Complexes of Trivalent Lanthanides and Yttrium

Saccharinate complexes of the fourteen trivalent lanthanide cations and Y^III were prepared by reaction between the respective lanthanide carbonates and saccharin in aqueous solution. Their crystal structures were determined by single crystal X‐ray diffractometry. They represent three different structural types. The first family, of composition [Ln(sac)(H₂O)₈](sac)₂�H₂O (sac = anion of saccharin; Ln = La, Ce, Pr, Nd.Sm, Eu), belongs to the monoclinic space group P2₁/c with Z = 4 and the Ln^III cation is in a tricapped trigonal prismatic environment with nine‐fold oxygen coordination. The second group of composition [Ln(sac)₂(H₂O)₆]‐(sac)(Hsac)�4H₂O with Ln = Gd, Dy, Ho, Er, Yb, Lu, and Y, pertains to the triclinic P1¯‐ space group, with Z = 2 and constitutes a new example of complexes containing simultaneously saccharin and its anion in the lattice. The Tm^III and Tb^III compounds, which are also triclinic (space group P1¯‐ and Z = 2) present two closely related structures conformed by three and two [Ln(sac)(H₂O)₇]²⁺ crystallographically independent complexes, respectively, with the [Tm(sac)(H₂O)₇]₃(sac)₆�9H₂O and [Tb(sac)(H₂O)₇]2(sac)₄�6H₂O composition. For all the heavier lanthanides (Gd‐Lu) and yttrium the cation presents eight‐fold oxygen coordination, with the ligands at the corners of a slightly distorted square Archimedean antiprism.     

Well-defined vanadium organoazide complexes and their conversion to terminal vanadium imides: structural snapshots and evidence for a nitrene capture mechanism

We report the synthesis and structural characterization of a family of well-defined organoazide complexes supported by a three-fold-symmetric pyrrolide scaffold and their conversion to the corresponding terminal imido congeners. Kinetic measurements on a series of structurally homologous but electronically distinct vanadium organoazide complexes reveal that the azido-to-imido transformations proceed via a process that is first-order in the metal complex and has a positive entropy of activation. Further studies suggest that these reactions may involve metal-mediated generation and capture of nitrene fragments.     

Continuous protein production in nanoporous, picolitre volume containers

The synthetic manufacture of functional proteins enables a bottom-up understanding of the workings of biological systems and opens new opportunities for the treatment of disease. Cell-free protein synthesis is a practical approach for enabling such manufacturing, however, it is typically carried out in fairly large volumes, when compared to a natural cell, leading to increases in cost and loss of efficiency. Here we demonstrate continuous cell free protein synthesis in arrays of cellular scale containers that continuously exchange energy and materials with their environment. A multiscale fabrication process allows the monolithic integration of nanoporous silicon containers within an addressable microfluidic network. Synthesis of enhanced green fluorescent protein (eGFP) in the containers continues beyond 24 h and yields more than twice the amount of protein, on a per volume basis, than conventional scale batch reactions. By mimicking the physical volume and controlled flux of a natural cell, the resulting "cell mimic" devices can enable fundamental studies of biological systems as well as serve applications related to the functional screening of proteins and the on-demand production of biologics.     

A structurally characterized nitrous oxide complex of vanadium

Nitrous oxide (N(2)O), a widespread greenhouse gas, is a thermodynamically potent and environmentally green oxidant that is an attractive target for activation by metal centers. However, N(2)O remains underutilized owing to its high kinetic stability, and the poor ligand properties of this molecule have made well-characterized metal-N(2)O complexes a rarity. We now report a vanadium-pyrrolide system that reversibly binds N(2)O at room temperature and provide the first single-crystal X-ray structure of such a complex. Further characterization by vibrational spectroscopy and DFT calculations strongly favor assignment as a linear, N-bound metal-N(2)O complex.     

New Saccharinato/Ammonia Complexes of Nickel(II) and Zinc(II). A Structural and Spectroscopic Study

Two new saccharinate/NH₃ complexes of composition [Ni(sac)₂(NH₃)₄] and [Zn(sac)₂(NH₃)₂] were obtained and their crystal structures determined by single crystal X‐ray diffractometry. The elongated octahedral Ni^II complex crystallizes in the monoclinic P2₁/c space group with Z = 2 whereas the tetrahedral Zn^II complex is triclinic (space group and Z = 2). For [Ni(sac)₂(NH₃)₄] the magnetic moment and electron absorption spectrum were obtained and discussed. The infrared spectra of both complexes were also recorded and briefly commented.     

Crystal and molecular structure determination,TGA-DTA,and infrared and Raman spectra of rubidium nitroprusside,Rb2[Fe(CN)5NO]

The title compound, Rb₂[Fe(CN)₅NO], crystallizes in the space group P2₁2₁2₁, witha=5.687(1),b=15.956(2),c=12.645(3) Å, andZ=4. Anions are in equivalent C₁ sites (one per asymmetric unit) and are slightly distorted octahedra (C_4v ideal symmetry). TGA and DTA curves and vibrational (infrared and Raman) spectra of Rb₂[Fe(CN)₅NO] were obtained. Results are interpreted in view of the crystal structure of the compound and the behavior of related substances.