Hydrothermal Synthesis of Luminescent Carbon Dots from Glucose and Birch Bark Soot

Carbon dots were prepared by the method of hydrothermal synthesis from carbon precursors of glucose and birch bark soot in aqueous ammonia. The distribution of lateral sizes of carbon dots testifies their average size to be 10–12 nm for glucose and 20–22 nm for soot. Infrared absorption spectra indicate oxygen groups on the surfaces of obtained carbon dots. Aqueous suspensions with glucose-based carbon dots exhibit strong absorption in the visible region from 300 nm to 500 nm. Soot-based carbon dots demonstrate strong absorption in the ultraviolet region, but are transparent in the visible region. The luminescence spectra exhibit that carbon dots synthesized from glucose and soot are luminescent in the same spectral region, their wavelengths of radiation depend on the wavelengths of excitation, and the intensity of luminescence depends on the presence of oxygen groups on the surface of carbon dots. Carbon dots synthesized from glucose and soot have great prospects in terms of their application in biology and medicine.     

Phase Equilibria in the System LiF–KI–KF–K<Subscript>2</Subscript>CrO<Subscript>4</Subscript>

Phase equilibria were experimentally studied in the system LiF–KI–KF–K₂CrO₄, which is the stable tetrahedron of the quaternary reciprocal system Li, K∥F, I, CrO₄. Differential thermal analysis revealed the compositions and transformation temperatures at the eutectic point E^□ 488 (L ? LiF + KF + KI + α-K₂CrO₄) and the peritectic point P^□ 510 (L + K₃FCrO₄ ? KI + α-K₂CrO₄ + KF). A computer model of the phase complex of the system was built, which can predict phase transformations at an arbitrary composition in the system. Isothermal sections of the systems were constructed, using which the phase composition at the temperature of the section can be calculated.     

WIN compounds: on the way to efficient antipicornaviral agent. A historical survey

Rhino- and enteroviruses of the Enterovirus genus of the Picornaviridae family are the causative agents of a wide variety of diseases. To date, neither synthetic antiviral drug nor an effective vaccine exists. A leading strategy to combat these viruses is the development of compounds with capsid-inhibiting activity that block viral uncoating and/or viral attachment to the host cell receptors. This review describes step-by-step development of the WIN compounds, which led to the discovery of pleconaril and the subsequent attempts to modify it in order to improve drug-like properties.

     

Synthesis and structure of bis(tetraphenylantimony) malonate

Russian Chemical Bulletin - Bis(tetraphenylantimony) malonate was synthesized by the reaction of tetraphenylantimony bromide with silver malonate (the molar ratio was 2:1) in toluene. According to...     

Sojourn time asymptotics in a parking lot network

For a two-class two-node bandwidth sharing network called parking lot network we investigate the tail behavior of the queue length and sojourn time under light-tailed assumptions. These results extend previous results in the literature obtained for a single-node network. Explicit conditions are given that indicate whether congestion at the second node influences the large deviations behavior or not. To overcome the complexities that arise when moving away from the single node case, we rely on recent results on overloaded bandwidth sharing networks obtained by Borst et al. (2009), and a comparison with the modified proportional fairness discipline, as introduced by Massoulié (Ann Appl Probab 17: 809–839, 2007). Specifically, our results include upper bounds for the distribution of the number of flows in the network, finiteness of the moment generating function of the workload, and large-deviations asymptotics for the sojourn time assuming flow size distributions having a bounded hazard rate.     

Controlled synthesis of oligomeric poly(acrylic acid) and its behavior in aqueous solutions

The controlled synthesis of oligomeric poly(acrylic acid) via the pseudoliving radical reversible addition-fragmentation chain-transfer polymerization of acrylic acid in bulk is developed. It is shown that, at high concentrations of reversible addition-fragmentation chain-transfer agents, the polymerization of acrylic acid in bulk occurs via the pseudoliving mechanism, as evidenced by a linear increase in the numberaverage molecular mass of oligomers with conversion and a narrow molecular-mass distribution of the reaction products. The surfactant properties and behavior of the oligomers in aqueous solutions are studied.     

Synthesis of new furopyrans and angularly fused furopyranochromenes from 3-arylmethylidenefuran-2-ones

Reactions of 5-aryl-3-arylmethylidenefuran-2-ones with malononitrile gave 6-amino-2,4-diaryl-4Hfuro[2,3-b]pyran-5-carbonitriles and 2-aryl-5-imino-5H,11bH-furo[3′,2′: 5,6]pyrano[3,4-c]chromen-6-amines as potentially biologically active substances.     

Phase transitions and the dielectric and piezoelectric properties of ceramic solid solutions based on BiScO<Subscript>3</Subscript>-PbTiO<Subscript>3</Subscript>

The ferroelectric and piezoelectric properties of ceramic solid solutions having a composition of (1−x)(Bi_0.9Nd_0.1)(Sc_0.9 B _0.1)O_{3 − x} PbTiO₃ (x = 0.60–0.66; B = Lu, Yb, Er, Y) and obtained by solid state reaction were studied. An increase in the Curie temperature was found upon an increase in the concentration of lead titanate, while a drop occured upon the doping of the A and B sublattices. It was shown that at high temperatures, MnO₂ and Bi₂O₃ additives lead to a reduction in the total conductivity and a dielectric loss of less than one order of magnitude. In modified ceramics, an increase in the d ₃₃ and k _t piezoelectric coefficients was observed as well. The effects of dielectric relaxation that are determined by the composition of the ceramics were revealed.     

Crystallographic Features of the α-Phase Structure in Hafnium and Hafnium–Titanium Alloys

Technical Physics - The structure of a hafnium crystal undergoing β → α (bcc → hcp) polymorphic transformation upon gradual cooling and the structure of Hf55Ti45 and Hf30Ti70...     

Novel Hybrid Benzoazacrown Ligand as a Chelator for Copper and Lead Cations: What Difference Does Pyridine Make

A synthetic procedure for the synthesis of azacrown ethers with a combination of pendant arms has been developed and the synthesized ligand, characterized by various techniques, was studied. The prepared benzoazacrown ether with hybrid pendant arms and its complexes with copper and lead cations were studied in terms of biomedical applications. Similarly to a fully acetate analog, the new one binds both cations with close stability constants, despite the decrease in both constants. The calculated geometry of the complexes correlate with the data from X-ray absorption and NMR spectroscopy. Coordination of both cations differs due to the difference between the ionic radii. However, these chelation modes provide effective shielding of cations in both cases, that was shown by the stability of their complexes in the biologically relevant media towards transchelation and transmetallation.