The vanishing limit of the square-well fluid: the adhesive hard-sphere model as a reference system

We report a simulation study of the gas-liquid critical point for the square-well potential, for values of well width delta as small as 0.005 times the particle diameter sigma. For small delta, the reduced second virial coefficient at the critical point B2*c is found to depend linearly on delta. The observed weak linear dependence is not sufficient to produce any significant observable effect if the critical temperature Tc is estimated via a constant B2*c assumption, due to the highly nonlinear transformation between B2*c and Tc. This explains the previously observed validity of the law of corresponding states. The critical density rho c is also found to be constant when measured in units of the cube of the average distance between two bonded particles (1+0.5 delta)sigma. The possibility of describing the delta-->0 dependence with precise functional forms provides improved accurate estimates of the critical parameters of the adhesive hard-sphere model.     

Volatile Compounds of Lemon and Grapefruit IntegroPectin

An HS-SPME GC-MS analysis of the volatile compounds adsorbed at the outer surface of lemon and grapefruit pectins obtained via the hydrodynamic cavitation of industrial waste streams of lemon and grapefruit peels in water suggests important new findings en route to understanding the powerful and broad biological activity of these new pectic materials. In agreement with the ultralow degree of esterification of these pectins, the high amount of highly bioactive α-terpineol and terpinen-4-ol points to limonene (and linalool) decomposition catalyzed by residual citric acid in the citrus waste peel residue of the juice industrial production.     

Fully solvable equilibrium self-assembly process: fine-tuning the clusters size and the connectivity in patchy particle systems

Self-assembly is the mechanism that controls the formation of well-defined structures from disordered pre-existing parts. Despite the importance of self-assembly as a manufacturing method and the increasingly large number of experimental realizations of complex self-assembled nano-aggregates, theoretical predictions are lagging behind. Here, we show that for a nontrivial self-assembly phenomenon, originating branched loopless clusters, it is possible to derive a fully predictive parameter-free theory of equilibrium self-assembly by combining the Wertheim theory for associating liquids with the Flory-Stockmayer approach for chemical gelation.     

Self-assembled Co(II) molecular squares incorporating the bridging ligand 4,7-phenanthrolino-5,6:5',6'-pyrazine

Three high-spin tetranuclear cobalt(II) complexes have been prepared with the bridging ligand 4,7-phenanthrolino-5,6:5',6'-pyrazine (ppz) through metal-ion directed self-assembly. The complexes differ by the incorporation of three different coordinating anions: chloride, thiocyanide and selenocyanide. The physical properties of these complexes have been investigated in detail.     

Effective cell uptake of nanoassemblies of a fluorescent amphiphilic cyclodextrin and an anionic porphyrin

An emitting nanoassembly composed of a novel amphiphilic cyclodextrin functionalised with a covalently appended fluorophore and an anionic porphyrin internalizes effectively in tumor cells, allowing simultaneously the detection of carrier and photosensitiser.     

Red Orange and Bitter Orange IntegroPectin: Structure and Main Functional Compounds

DRIFT, HPLC-MS, and SPME-GC/MS analyses were used to unveil the structure and the main functional compounds of red (blood) orange (Citrus sinensis) and bitter orange (Citrus aurantium). The IntegroPectin samples show evidence that these new citrus pectins are comprised of pectin rich in RG-I hairy regions functionalized with citrus biophenols, chiefly flavonoids and volatile molecules, mostly terpenes. Remarkably, IntegroPectin from the peel of fresh bitter oranges is the first high methoxyl citrus pectin extracted via hydrodynamic cavitation, whereas the red orange IntegroPectin is a low methoxyl pectin. C. aurantium IntegroPectin has a uniquely high concentration of adsorbed flavonoids, especially the flavanone glycosides hesperidin, naringin, and eriocitrin.     

Novel heterotopic colloids of anionic porphyrins entangled in cationic amphiphilic cyclodextrins: spectroscopic investigation and intracellular delivery

The entanglement process between water-soluble 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine and the amphiphilic cyclodextrin (CD) heptakis(2-omega-amino-O-oligo(ethylene oxide)-6-hexylthio)-beta-CD and the occurrence of various species at different porphyrin:CD ratios were studied by a combination of UV/Vis absorption, fluorescence anisotropy, time-resolved fluorescence, resonance light scattering, and circular dichroism. The effect of the entanglement process on the mean vesicle diameter was investigated over a wide concentration range by quasielastic light-scattering techniques. The experimental results indicate that the presence of porphyrins in this colloidal system promotes some structural rearrangements, essentially driven by charge interaction, which are responsible for a sensitive change of vesicle dimensions. In the range of porphyrin:CD molar ratios between 1:10 and 1:50, the porphyrin is solubilized in monomeric form (tau(1)=11.5 ns) and photosensitizes the production of singlet oxygen ((1)O(2)). At the same molar ratio the ability of this amphiphilic cyclodextrin to transport porphyrins into tumor cells indicates specificity at the nuclear-compartment level. These findings may be of potential interest for the of development agents for photodynamic therapy of tumors.     

Aging in short-ranged attractive colloids: a numerical study

We study the aging dynamics in a model for dense simple liquids, in which particles interact through a hard-core repulsion complemented by a short-ranged attractive potential, of the kind found in colloidal suspensions. In this system, at large packing fractions, kinetically arrested disordered states can be created both on cooling (attractive glass) and on heating (repulsive glass). The possibility of having two distinct glasses, at the same packing fraction, with two different dynamics offers the unique possibility of comparing-within the same model-the differences in aging dynamics. We find that, while the aging dynamics of the repulsive glass is similar to the one observed in atomic and molecular systems, the aging dynamics of the attractive glass shows novel unexpected features.