Ultrasonication-assisted spray ionization mass spectrometry for on-line monitoring of organic reactions

A straightforward on-line monitoring of organic reactions by ultrasonication-assisted spray ionization mass spectrometry (UASI MS) is demonstrated in this work.     

Agitation-free multiphoton microscopy of oblique planes

The scanning two-photon fluorescence microscope produces optically sectioned images from the focal plane. It is sometimes desirable to acquire images from other planes of the specimen that are inclined with respect to the focal plane. In this Letter, we discuss the issues concerned with acquiring such images together with the effects of the inclination angle on image resolution and sectioning strength. To obtain images from oblique planes at high speed, a two-photon system was built wherein a novel optical system is used to provide aberration-free scanning.     

Copper(II) complexes with the N,N,O-tridentate ligand 6-amino-5-formyl-1,3-dimethyluracilato-(N6)-benzoylhydrazone: synthesis, spectral and XRD studies

From reactions between different Cu(II) salts and the Schiff base 6-amino-5-formyl-1,3-dimethyluracil-benzoylhydrazone (H₂BEZDO) in alcohol, six new copper complexes with simplified formulas [Cu(HBEZDO)(H₂O)(MeOH)]NO₃ (1), [CuCl(HBEZDO)(DMF)] (2), [CuBr(HBEZDO)]·2H₂O (3), CuBr(HBEZDO) (4), Cu(ClO₄)(HBEZDO)·H₂O (5), and Cu(SO₄)_1/2(HBEZDO)·1 H₂O (6) were isolated. The structures of compounds 1, 2 and 3 have been established by means of XRD diffraction methods. In the three compounds, the Schiff base acts as a tridentate monodeprotonated ligand through the N(6), N(51) and O(52) atoms, making two five- and six-membered chelate rings. In the structure of 1 and 2, the solvent molecules are coordinated giving square-based pyramidal environments, with the basal plane completed by a MeOH (1) or Cl (2) and the apical positions occupied by the oxygen atom of a water (1) or a DMF molecule (2). The molecular unit of the complex [CuBr(HBEZDO)]·2H₂O (3) is defined by a square-plane containing the three donor atoms of the organic ligand and a bromide ligand (Cu–Br 2.384 Å), but there is a stronger tetragonally elongated pyramidal geometry around the metal, the apical position of the polyhedron being occupied by a weakly bound-to-copper bromine atom (3.086 Å) of a neighbouring molecule. This fact gives the appearance of an apparent dimer with very asymmetric bromine bridges, in which there are no exchange interactions between metal centres. Also, infrared, magnetic and EPR data of the isolated complexes are reported.     

Intra-arterial application of magnetic nanoparticles for targeted thrombolytic therapy: A rat embolic model

Targeted delivery of thrombolytic drug to the site of emboli exhibits potential to greatly reduce hemorrhagic side effect. A rat embolic model with an easy access of a magnet was established for study of the efficacy of magnetic drug targeting. In anesthetized rats, a whole blood clot produced in vitro was injected from the right iliac artery and lodged in the left iliac artery. Intra-arterial infusion of recombinant tissue plasminogen activator (rt-PA) thereafter significantly reversed the iliac flow within 15 min. Placement of an NdFeB magnet above the left iliac artery caused magnetic nanoparticle retention against hemodynamic dragging force in the presence and absence of the clot. Our results suggest the feasibility of this rat embolic model for the study of magnetic targeted delivery of thrombolytic drugs.     

Block thresholding for density estimation: local and global adaptivity

We consider wavelet block thresholding method for density estimation. A block-thresholded density estimator is proposed and is shown to achieve optimal global rate of convergence over Besov spaces and simultaneously attain the optimal adaptive pointwise convergence rate as well. These results are obtained in part through the determination of an optimal block length.     

Enantioselective synthesis of the carbacephem antibiotic loracarbef via Mitsunobu and Dieckmann cyclization from an unnatural amino acid

The nucleus of the carbacephem antibiotic loracarbef was synthesized in a highly efficient and enantioselective fashion from 2S,3S-2-amino-3-hydroxy-6-heptenoic acid (AHHA), which was derived from enzyme-catalyzed condensation of glycine and 4-pentenaldehyde. The bicyclic framework of this compound was established through sequential Mitsunobu reaction and aldol condensations.     

A comparison study on multivariant and univariant finite elements for three-dimensional incompressible viscous flows

In this paper, four quadratic hexahedron elements are considered and assessed for analysis of an incompressible viscous flow underlying the mixed finite element method. We classify the investigated elements as multivariant and univariant finite elements. With the same number of pressure unknowns, multivariant elements are more constrained when the number of elements per side is larger than 10, as compared with that of continuous pressure elements. In multivariant eléments, the coding is complicated by the appearance of restricted degrees of freedom at mid-face and mid-edge nodes. The comparison consequently should be made via numerical example against the analytical problem.     

Can Gravitons be Detected?

Freeman Dyson has questioned whether any conceivable experiment in the real universe can detect a single graviton. If not, is it meaningful to talk about gravitons as physical entities? We attempt to answer Dyson’s question and find it is possible concoct an idealized thought experiment capable of detecting one graviton; however, when anything remotely resembling realistic physics is taken into account, detection becomes impossible, indicating that Dyson’s conjecture is very likely true. We also point out several mistakes in the literature dealing with graviton detection and production.