Optimization of malaria detection based on third harmonic generation imaging of hemozoin

The pigment hemozoin is a natural by-product of the metabolism of hemoglobin by the parasites which cause malaria. Previously, hemozoin was demonstrated to have a very high nonlinear optical response enabling third harmonic generation (THG) imaging. In this study, we present a complete characterization of the nonlinear THG response of natural hemozoin in malaria-infected red blood cells, as well as in pure isostructural synthesized hematin anhydride, in order to determine optimal imaging parameters for detection. Our study demonstrates the wavelength range for optimal pulsed femtosecond laser excitation of THG from hemozoin crystals. In addition, we show the hemozoin crystal detection as a function of crystal size, incident laser power, and the emission response of the hemozoin crystals to different incident laser polarization states. Our systematic measurements of the nonlinear optical response from hemozoin establish detection limits, which are essential for the optimal design of malaria detection technologies that exploit the THG response of hemozoin.

Elastic properties of the Ta–V system: bcc Ta0.33V0.67 and C15 TaV2

Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta_0.33V_0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV₂. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase.     

Irradiation of a cone by a magnetic dipole

Th electromagnetic field produced by a magnetic dipole in thepresence of a perfectly conducting cone of arbitrary cross-sectionis determined. The solution is used to find out how a currenton the cone travelling towards the apex is reflected. Some valuesof the reflection coefficient are calculated. In particular,it is shown that there is a sort of resonance with the reflectionincreasing significantly as the cone approaches a plane.     

Decarboxylation and ring fragmentation reactions of sydnone N-oxides

4-Carboxylated sydnone N-oxides are readily decarboxylated by benzylation to give 2,4-dibenzylsydnone-N-oxides. Ring cleaveage results from their oxidation with bromine which leads to a nitrile N-oxide which is isolated as its furazan dimer.     

The Sulfur Rich Fluorothiophosphate Dianions [S5P2F2]2− and [S3PF]2− : Cluster and Chelation Control of P-S Heterolysis

The sulfur rich difluoropentathiodiphosphate dianion [S₅P₂F₂]²⁻, from fluoride addition to P₄S₁₀, has a somewhat checkered history and proves to be the main product of the reaction in acetonitrile. Its optimized synthesis, and structural characterization, as either a tetraphenylphosphonium or a tetrapropylammonium salt, [NⁿPr₄]₂[S₅P₂F₂] allows for the first coordination chemistry for this dianion. Reactions of [S₅P₂F₂]²⁻ with d¹⁰ metal ions of zinc(II), and cadmium(II), and d⁹ copper(II) resulted in a surprising diverse array of binding modes and structural motifs. In addition to the simple bis-chelate coordination of [S₅P₂F₂]²⁻ with zinc, cleavage of the P−S bond resulted in complexes with the unusual [S₃PF]²⁻ fluorotrithiophosphate dianion. This was observed in two cluster complexes: a trinuclear cadmium complex with mixed [S₅P₂F₂]²⁻/[S₃PF]²⁻ ligands, [Cd₃(S₅P₂F₂)₃(S₃PF)₂]⁴⁻ as well as an octanuclear copper cluster, [Cu₈(S₃PF)₆]⁴⁻ which form rapidly at room temperature. These new metal/sulfur/ligand clusters are of relevance to understanding multimetal binding to metallothionines, and to potential capping strategies for the condensed nanoparticulate cadmium chalcogenide semiconductors CdS and CdSe.     

Structural studies and T c dependence in La2−x Dy x Ca y Ba2Cu4+y O z type mixed oxide superconductors

A new series of mixed oxide superconductors with the stoichiometric composition La_2−x Dy _x Ca _y Ba₂Cu_4+y O _z (x=0.0 − 0.5, y=2x) has been studied for structural and superconductiong properties. Our earlier studies on La_2−x (Y/Er) _x Ca _y Ba₂Cu_4+y O _z series, show a strong dependence of T _c on hole concentration (p _sh). In the present work, the results of the analysis of the neutron diffraction measurements at room temprerature on x=0.3 and 0.5 samples are reported. It is interesting to know that Ca substitutes for both La and Ba site with concomitant displacement of La onto Ba site. Superconductivity studies show that maximum T _c is obtained for x=0.5, y=1.0 sample (T _c ∼ 75 K), for La_1.5Dy_0.5Ca₁Ba₂Cu₅O _z (La-2125).     

New methanetrisdiazeniumdiolates

Acetophenone and 1,3-biacetylbicyclo[1.1.1]pentane exhaustively condense all acidic α CH with nitric oxide in basic methanol to give methanetrisdiazeniumdiolates, RC(O)C(N₂O₂K)₃ either as a trianionic salt in the case of acetophenone or as a hexanionic salt in the case of 1,3-biacetylbicyclo[1.1.1]pentane.     

General Two‐Step Preparation of Chalcones Containing Thiazole

2‐Aryl‐4‐methyl‐5‐acetylthiazoles, which were prepared from arylthioamides and chloroacetylacetone, were treated with 6‐substituted‐3‐formylchromones or arylaldehydes to give a series of eighteen new thiazolylchalcones in good yields. The structures of all the synthesized compounds were characterized by ¹H NMR, ¹³C NMR, and ES‐MS spectrometry. Additionally, the crystal structures of two of these chalcones were determined by X‐ray diffraction analysis.