A Gilbert-Varshamov-type bound for lattice packings

A Gilbert-Varshamov-type bound for Euclidean packings was recently found by Nebe and Xing. In this present paper, we derive a Gilbert-Varshamov-type bound for lattice packings by generalizing Rush's approach of combining p-ary codes with the lattice pZn. Specifically, we will exploit suitable sublattices of Zn as well as lattices of number fields in our construction. Our approach allows us to compute the center densities of lattices of moderately large dimensions which compare favorably with the best known densities given in the literature as well as the densities derived directly via Rush's method.     

Reduction of <Superscript>68</Superscript>Ge activity containing liquid waste from <Superscript>68</Superscript>Ga PET chemistry in nuclear medicine and radiopharmacy by solidification

PET with ⁶⁸Ga from the TiO₂- or SnO₂- based ⁶⁸Ge/⁶⁸Ga generators is of increasing interest for PET imaging in nuclear medicine. In general, radionuclidic purity (⁶⁸Ge vs. ⁶⁸Ga activity) of the eluate of these generators varies between 0.01 and 0.001%. Liquid waste containing low amounts of ⁶⁸Ge activity is produced by eluting the ⁶⁸Ge/⁶⁸Ga generators and residues from PET chemistry. Since clearance level of ⁶⁸Ge activity in waste may not exceed 10 Bq/g, as stated by European Directive 96/29/EURATOM, our purpose was to reduce ⁶⁸Ge activity in solution from >10 kBq/g to <10 Bq/g; which implies the solution can be discarded as regular waste. Most efficient method to reduce the ⁶⁸Ge activity is by sorption of TiO₂ or Fe₂O₃ and subsequent centrifugation. The required 10 Bq per mL level of ⁶⁸Ge activity in waste was reached by Fe₂O₃ logarithmically, whereas with TiO₂ asymptotically. The procedure with Fe₂O₃ eliminates ≥90% of the ⁶⁸Ge activity per treatment. Eventually, to simplify the processing a recirculation system was used to investigate ⁶⁸Ge activity sorption on TiO₂, Fe₂O₃ or Zeolite. Zeolite was introduced for its high sorption at low pH, therefore ⁶⁸Ge activity containing waste could directly be used without further interventions. ⁶⁸Ge activity containing liquid waste at different HCl concentrations (0.05–1.0 M HCl), was recirculated at 1 mL/min. With Zeolite in the recirculation system, ⁶⁸Ge activity showed highest sorption.     

Bi-functional gold-coated magnetite composites with improved biocompatibility

The effect of gold attachment on the physical characteristics, cellular uptake, gene expression efficiency, and biocompatibility of magnetic iron oxide (MNP) vector was investigated in vitro in BHK21 cells. The surface modification of magnetite with gold was shown to alter the morphology and surface charge of the vector. Nonetheless, despite the differences in the surface charge with and without gold attachment, the surface charge of all vectors were positive when conjugated with PEI/DNA complex, and switched from positive to negative when suspended in cell media containing serum, indicating the adsorption of serum components onto the composite. The cellular uptake of all MNP vectors under the influence of a magnetic field increased when the composite loadings increased, and was higher for the MNP vector that was modified with gold. Both bare magnetite and gold-coated magnetite vectors gave similar optimal gene expression efficiency, however, the gold-coated magnetite vector required a 25-fold higher overall loading to achieve a comparable efficiency as the attachment of gold increased the particle size, thus reducing the surface area for PEI/DNA complex conjugation. The MNP vector without gold showed optimal gene expression efficiency at a specific magnetite loading, however further increases beyond the optimum loading decreased the efficiency of gene expression. The drop in efficiency at high magnetite loadings was attributed to the significant reduction in cellular viability, indicating the bare magnetite became toxic at high intracellular levels. The gene expression efficiency of the gold-modified vector, on the other hand, did not diminish with increasing magnetite loadings. Intracellular examination of both bare magnetite and gold-coated magnetite vectors at 48h post-magnetofection using transmission electron microscopy provided evidence of the localization of both vectors in the cell nucleus for gene expression and elucidated the nuclear uptake mechanism of both vectors. The results of this work demonstrate the efficacy of gold-modified vectors to be used in cellular therapy research that can function both as a magnetically-driven gene delivery vehicle and an intracellular imaging agent with negligible impact on cell viability.     

Synthesis of azaheterocycles from aryl ketone O-acetyl oximes and internal alkynes by Cu-Rh bimetallic relay catalysts

A synthetic method for azaheterocycles from aryl ketone O-acetyl oximes and internal alkynes has been developed by using the Cu(OAc)(2)-[Cp*RhCl(2)](2) bimetallic catalytic system. The reactions proceeded with both of anti- and syn-isomers of oximes with a wide scope of substituents. The Cu-Rh bimetallic system could be applied for the synthesis of isoquinolines as well as β-carboline, furo[2.3-c]pyridine, pyrrolo[2,3-c]pyridine, and thieno[2,3-c]pyridine derivatives.     

The critical importance of size on thermoresponsive nanoparticle transition temperatures: gold and micelle-based polymer nanoparticles

The synthesis and application of thermally-responsive macromolecules and nanoparticles relies on the underpinning control of their transition temperatures. The present study shows that two structurally diverse classes of nanoparticle have very strong diameter-dependent responses to temperature-stimuli, demonstrating that the exact size of the nanostructure can significantly impact its performance.     

Luminescent Cyanoruthenate(II)?Diimine and Cyanoruthenium(II)?Diimine Complexes

To improve the emission and excited‐state properties of luminescent cyanometalates, new classes of highly solvatochromic luminescent cyanoruthenium(II) and cyanoruthenate(II) complexes of the general formulae [Ru(PR₃)₂(CN)₂($\widehat{NN}$ )] and K[Ru(PR₃)(CN)₃($\widehat{NN}$ )], respectively, were developed. These complexes could be readily synthesized through the ligand‐substitution reaction of K₂[Ru(CN)₄(PR₃)₂] with a diimine ligand. The geometrical isomerism of these complexes was characterized by using various spectroscopic techniques. Their photophysical properties, solvatochromism, and electrochemistry have also been investigated. Our detailed study showed that many of these complexes exhibited extremely environmentally sensitive emissions and significantly improved emission quantum efficiencies and lifetimes compared with the well‐studied tetracyanoruthenate systems.     

NOVEL SYNTHESIS OF THIAZOLIDINES

Abstract

A novel synthesis of thiazolidine derivatives is described, based on nucleophilic additions across the triple bond of 1,4-diarylsulfonyl-2-butynes. The use of bidentate nucleophiles like N,N′-dialkylthioureas, under mild base catalysis, at ambient conditions affords good yields of the title compounds. A mechanism for the formation of the compounds is offered and supported by appropriate experiments.     

Reliability of protonation constants of vildagliptin dimers by the regression analysis of pH-titration data

Protonation constants of protonated monomers and dimers of the vildagliptin are determined potentiometrically. For the low concentration c _L = 3.3 mmol dm^?3 the monomers L and LH dominate, while for a higher concentration c _L = 6.3 mmol dm^?3 the dimers L₂H₂, L₂H₃, L₂H₄ and L₂H are mainly present. The algorithm used has little influence on the precision of the formation constants in comparison with the reproducibility of the titration. The mixed protonation constants of vildagliptin dimers L _q H _r at various temperatures are determined using FBSTAC4 and HYPERQUAD regression analysis of the potentiometric titration data. The accuracy of the protonation constants log₁₀ β _qr depends on the accuracy of the group parameters. As two group parameters L ₀, H _T are ill conditioned in a model, their determination is therefore uncertain; both can significantly cause a systematic error in the estimated common parameters log₁₀ β _qr . Using various regression diagnostics the goodness-of-fit proves the reliability of all parameter estimates. A rough estimation of thermodynamic enthalpies ΔH ⁰ (kJ mol^?1) and entropies ΔS ⁰ (J K^?1 mol^?1) is determined from the temperature variation of protonation constants. The enthalpy shows the protonation process is exothermic, and the entropy indicates that it is spontaneous.