Fructose-derived hydrochar: combustion thermochemistry and kinetics assessments

Journal of Thermal Analysis and Calorimetry - The combustion behavior of fructose-derived hydrochar was investigated using a kinetic evaluation protocol that brings about novel elements related to...     

Biochemistry of the para-sulfonato-calix[n]arenes

The biochemistry of the para-sulfonato-calix[n]arenes has shown rapid development during the past ten years, the highly diverse biomedical applications of these molecules now include anti-viral, anti-thrombotic activities, enzyme blocking and protein complexation. The future is even more promising as para-sulfonato-calix[n]arenes have, now, been shown to have potential in the diagnosis of prion-based diseases. Their innocuous nature, as far as is known at present, may open up their future use in medications.     

Synthesis and Biological Characterization of Monomeric and Tetrameric RGD-Cryptophycin Conjugates

The effective delivery of cytotoxic agents to tumor cells is a key challenge in anticancer therapy. Multivalent integrinspecific ligands are considered a promising tool to increase the binding affinity, selectivity, and internalization efficiency of small-molecule drug conjugates. Herein, we report the synthesis and biological evaluation of a multimeric conjugate containing the high-affinity integrin α_vβ₃ binding ligand RAFT-c(RGDfK)₄, a lysosomally cleavable Val-Cit linker, and cryptophycin-55 glycinate, a potent inhibitor of tubulin polymerization. In vitro cytotoxicity assays verified that the multimeric RGD-cryptophycin conjugate displays improved potency compared to the monomeric analogue in integrin α_vβ₃ overexpressing tumor cell lines, while significantly reduced activity was observed in the integrin-negative cell line.     

Vitamin B12 supported on graphene oxide: As a bio‐based catalyst for selective aerobic oxidation of alcohols

The environmental impact of chemical processes has now opened new windows of opportunity for bio‐based catalysts. In this paper a highly active bio‐based catalyst of vitamin B₁₂ supported on graphene oxide nanosheets is reported for the selective aerobic oxidation of alcohols to the corresponding carbonyl compounds. Operational simplicity, mild reaction conditions, high yield and selectivity, non‐hazardous nature, commercial availability and affordability are the main advantages of this novel catalytic system.     

Carbohydrates electrocatalytic oxidation using CNT-NiCo-oxide modified electrodes

A new sensor for an amplified electrochemical detection of carbohydrates is proposed, where carbohydrates are oxidized by CNT-NiCo-oxide composite in basic solutions. Cyclic voltammograms of the modified electrode show a stable and well defined redox couple in alkaline media due to the synergy of Ni(II)/Ni(III) system with Co(II)/Co(III). The modified electrode shows excellent electrocatalytic activity towards monosaccharides oxidation at reduced overpotential in alkaline solutions. Six monosaccharides were determined amperometrically at the surface of this modified electrode with high sensitivity over a wide range of concentrations, from 0.02 up to 12.12 mM. Low detection limit of 5 μM for glucose could be obtained.     

The NADH Electrochemical Detection Performed at Carbon Nanofibers Modified Glassy Carbon Electrode

In this work, the capability of carbon nanofibers to be used for the design of catalytic electrochemical biosensors is demonstrated. The direct electrochemistry of NADH was studied at a glassy carbon electrode modified using carbon nanofibers. A decrease of the oxidation potential of NADH by more than 300 mV is observed in the case of the assembled carbon nanofiber‐glassy carbon electrode comparing with a bare glassy carbon electrode. The carbon nanofiber‐modified electrode exhibited a wide linear response range of 3×10^?5 to 2.1×10^?3 mol L^?1 with a correlation coefficient of 0.997 for the detection of NADH, a high specific sensitivity of 3637.65 (μA/M cm²), a low detection of limit (LOD=3σ) of 11 μM, and a fast response time (3 s). These results have confirmed the fact that the carbon nanofibers represent a promising material to assemble electrochemical sensors and biosensors.     

Kinetics of exothermal decomposition of 2-nitrophenylhydrazine and 4-nitrophenylhydrazine using DSC non-isothermal data

Kinetics of exothermal decomposition of 2-nitrophenylhydrazine (2-NPH) and 4-nitrophenylhydrazine (4-NPH) was investigated by differential scanning calorimetry. The isoconversional methods, Friedman and Flynn-Wall-Ozawa, were applied to determine the activation parameters from the common analysis of multiple curves measured at different heating rates. For the processes involving two-step reactions the multivariate non-linear regression was used. A good agreement between the experimental and the fitted data was found.     

Anionic fullerenes, calixarenes, coronenes, and pyrenes as activators of oligo/polyarginines in model membranes and live cells

We report that the efflux of 5(6)-carboxyfluorescein anions from neutral egg yolk phosphatidylcholine vesicles is mediated by oligo/polyarginines only in the presence of activating amphiphilic anions. Screening of anion activators reveals best synergism for amphiphilic carboxylates (fullerene > calix[4]arene approximately coronene > pyrene > calix[6]arene > alkyl), whereas amphiphilic sulfates show less satisfactory activation despite often lower effective concentrations. The analogous alcohols and one calix[4]arene diphosphate were inactive. These results are discussed in the context of a tentative anion carrier mechanism, where interactions with bilayer (interface-directed translocation) and carrier (arene-templated carboxylate-guanidinium pairing) contribute to activator efficiencies. Applied to HeLa cells, pyrenebutyrate is shown to significantly increase the uptake of a fluorescently labeled octaarginine in a concentration-dependent manner.     

Perron Conditions for Uniform Exponential Expansiveness of Linear Skew-Product Flows

 We present necessary and sufficient conditions for uniform exponential expansiveness of discrete skew-product flows, in terms of uniform complete admissibility of the pair (c ₀(N, X), c ₀(N, X)). We give discrete and continuous characterizations for uniform exponential expansiveness of linear skew-product flows, using the uniform complete admissibility of the pairs (c ₀(N, X), c ₀(N, X)) and (C ₀(R ₊, X), C ₀(R ₊, X)), respectively. We generalize an expansiveness theorem due to Van Minh, R?biger and Schnaubelt, for the case of linear skew-product flows.     

Perron Conditions for Uniform Exponential Expansiveness of Linear Skew-Product Flows

 We present necessary and sufficient conditions for uniform exponential expansiveness of discrete skew-product flows, in terms of uniform complete admissibility of the pair (c ₀(N, X), c ₀(N, X)). We give discrete and continuous characterizations for uniform exponential expansiveness of linear skew-product flows, using the uniform complete admissibility of the pairs (c ₀(N, X), c ₀(N, X)) and (C ₀(R ₊, X), C ₀(R ₊, X)), respectively. We generalize an expansiveness theorem due to Van Minh, R?biger and Schnaubelt, for the case of linear skew-product flows. Received August 10, 2001; in revised form June 25, 2002