Experimental verification of fractional history effects on the viscous dynamics of small spherical particles

We investigate the low Reynolds, high-frequency particle response of non-neutrally buoyant particles suspended in a fluid. Gravity effects are suppressed by means of a very thin tether, whose effect on the horizontal movement of the particle is negligible due to the small amplitude, high-frequency nature of the forcing. The measured stationary responses of particles of different densities closely match the theoretical predictions for the full solution, including Basset history effects for both the amplitude ratio and the phase, and clearly differ from the solution where the history force is neglected.     

Different Enzyme Conformations Induce Different Mechanistic Traits in HIV-1 Protease

The influence of the dynamical flexibility of enzymes on reaction mechanisms is a cornerstone in biological sciences. In this study, we aim to 1) study the convergence of the activation free energy by using the first step of the reaction catalysed by HIV-1 protease as a case study, and 2) provide further evidence for a mechanistic divergence in this enzyme, as two different reaction pathways were seen to contribute to this step. We used quantum mechanics/molecular mechanics molecular dynamics simulations, on four different initial conformations that led to different barriers in a previous study. Despite the sampling, the four activation free energies still spanned a range of 5.0 kcal ⋅ mol⁻¹. Furthermore, the new simulations did confirm the occurrence of an unusual mechanistic divergence, with two different mechanistic pathways displaying equivalent barriers. An active-site water molecule is proposed to influence the mechanistic pathway.     

Pt(II) complexes with bidentate and tridentate pyrazolyl-containing chelators: synthesis, structural characterization and biological studies

A series of four Pt(II) complexes anchored by bidentate or tridentate pyrazolyl-alkylamine chelators bearing different substituents at the azolyl rings has been prepared with the aim to assess their interest in the design of novel anticancer drugs. All complexes have been fully characterized by classical analytical methods and three of them were characterized also by X-ray diffraction analysis. Their solution behavior, together with lipophilicity measurements, cell uptake, antiproliferative properties, DNA interaction have been evaluated. Albeit all the complexes were less active than cisplatin on ovarian carcinoma A2780 cell line, greatly retained their activity in the cisplatin-resistant A2780cisR cell line and presented a lower resistance factor compared to cisplatin. Moreover, the Pt(II) complexes under investigation were less prone to undergo deactivation by glutathione, believed to be the major cellular target of cisplatin that inactivates the drug by binding to it irreversibly.     

A nonionic porphyrin as a noninterfering DNA antibacterial agent

The increasing interest in clinical bacterial photodynamic inactivation has led to the search for photosensitizers with higher bactericidal efficiency and less side effects on the surrounding tissues. We present a novel nonionic porphyrin, the 5,10,15-tris(2,6-dichlorophenyl)-20-[4-N-(6-amino-hexyl)sulfonamido)phenyl]-porphyrin (ACS769F4) with substantial improvements in the efficiency of nonionic sensitizers. This porphyrin causes eradication of both Escherichia coli and Staphylococcus aureus by the photodynamic effect but in higher concentrations compared with 5,10,15,20-tetrakis (4-N,N,N-trimethylammoniumphenyl)-porphyrin p-tosylate (TTAP(4+)), a known bactericidal tetracationic porphyrin. More important, under such conditions, ACS769F4 proved to be harmless to two mammalian cells lines (human embryonic and baby hamster kidney), causing no reduction in their viability or negative impact on their cytoskeleton, despite its accumulation in cellular structures. On the contrary, TTAP(4+) is shown to accumulate in the nucleus of mammalian cells, in association to DNA, causing chromatin condensation after exposure to light. Furthermore, dark incubation with TTAP(4+) was shown to have a deleterious effect on the microtubule network. Based on its bactericidal efficiency, also observed without exposure to light, and on the low tendency to be harmful or genotoxic to mammalian cells, ACS769F4 should be looked at as an interesting photosensitizer to be evaluated for clinical purposes.     

The effect of topical anesthesia on vocal fold motion

The objective of this study was to determine if topical anesthesia to the larynx and pharynx affects vocal fold motion during dynamic voice evaluation with transnasal flexible endoscopy. Transnasal dynamic laryngeal examinations of 10 patients with no voice complaints were evaluated by five blinded fellowship-trained laryngologists. Each patient was examined before and after application of topical anesthetic. Reviewers rated briskness of right and left vocal fold movement and longitudinal tension on a visual analogue scale. Statistical comparisons were made between individual subject scores before and after anesthetic application. Inter-rater reliability was also assessed. No statistical difference was observed between subject scores before and after anesthetic application. Average intraclass correlation coefficients were 0.643 and 0.591 for pre- and postanesthesia scores, respectively. Application of topical anesthesia to the larynx and pharynx does not affect vocal fold motion.     

Neutral and acidic products derived from hydroxyl radical‐induced oxidation of arabinotriose assessed by electrospray ionisation mass spectrometry

The oxidation of α‐(1 → 5)‐l ‐arabinotriose (Ara₃), an oligosaccharide structurally related to side chains of coffee arabinogalactans, was studied in reaction with hydroxyl radicals generated under conditions of Fenton reaction (Fe²⁺/H₂O₂). The acidic and neutral oxidation products were separated by ligand exchange/size‐exclusion chromatography, subsequently identified by electrospray ionisation mass spectrometry (ESI–MS) and structurally characterised by tandem MS (ESI–MS/MS). In acidic fraction were identified several oxidation products containing an acidic residue at the corresponding reducing end of Ara₃, namely arabinonic acid, and erythronic, glyceric and glycolic acids formed by oxidative scission of the furanose ring. In neutral fractions were identified derivatives containing keto, hydroxy and hydroperoxy moieties, as well as derivatives resulting from the ring scission at the reducing end of Ara₃. In both acidic and neutral fractions, beyond the trisaccharide derivatives, the corresponding di‐ and monosaccharide derivatives were identified indicating the occurrence of oxidative depolymerisation. The structural characterisation of these oxidation products by ESI–MS/MS allowed the differentiation of isobaric and isomeric species of acidic and neutral character. The species identified in this study may help in detection of roasting products associated with the free radical‐mediated oxidation of coffee arabinogalactans. Copyright © 2014 John Wiley & Sons, Ltd.     

Optimal decay rates for the system of elastic waves in R n with structural damping

We consider the Cauchy problem in R ⁿ for the system of elastic waves with structural damping. We derive (almost) optimal decay rates in time for the L ²-norm and the total energy which improves previous results for this system. To derive the estimates for elastic waves, we employ an improvement in a method in the Fourier space, which was developed in our previous works. Our estimates came from those for a generalized energy of α-order in the Fourier space.     

ScannerS: constraining the phase diagram of a complex scalar singlet at the LHC

We present the first version of a new tool to scan the parameter space of generic scalar potentials, ScannerS (Coimbra et al., ScannerS project., 2013). The main goal of ScannerS is to help distinguish between different patterns of symmetry breaking for each scalar potential. In this work we use it to investigate the possibility of excluding regions of the phase diagram of several versions of a complex singlet extension of the Standard Model, with future LHC results. We find that if another scalar is found, one can exclude a phase with a dark matter candidate in definite regions of the parameter space, while predicting whether a third scalar to be found must be lighter or heavier. The first version of the code is publicly available and contains various generic core routines for tree level vacuum stability analysis, as well as implementations of collider bounds, dark matter constraints, electroweak precision constraints and tree level unitarity.     

Headspace solid phase microextraction and gas chromatography-quadrupole mass spectrometry methodology for analysis of volatile compounds of marine salt as potential origin biomarkers

The establishment of geographic origin chemical biomarkers for the marine salt might represent an important improvement to its valorisation. Volatile compounds of marine salt, although never studied, are potential candidates. Thus, the purpose of this work was the development of a headspace solid phase microextraction (SPME) combined with gas chromatography-quadrupole mass spectrometry (HS-SPME/GC-qMS) methodology to study the volatile composition of marine salt. A 65 μm carbowax/divinylbenzene SPME coating fibre was used. Three SPME parameters were optimised: extraction temperature, sample quantity, and presentation mode. An extraction temperature of 60 °C and 16 g of marine salt in a 120 mL glass vial were selected. The study of the effect of sample presentation mode showed that the analysis of an aqueous solution saturated with marine salt allowed higher extraction efficiency than the direct analysis of salt crystals. The dissolution of the salt in water and the consequent effect of salting-out promote the release of the volatile compounds to the headspace, enhancing the sensitivity of SPME for the marine salt volatiles. The optimised methodology was applied to real matrices of marine salt from different geographical origins (Portugal, France, and Cape Verde). The marine salt samples contain ca. 40 volatile compounds, distributed by the chemical groups of hydrocarbons, alcohols, phenols, aldehydes, ketones, esters, terpenoids, and norisoprenoids. These compounds seem to arise from three main sources: algae, surrounding bacterial community, and environment pollution. Since these volatile compounds can provide information about the geographic origin and saltpans environment, this study shows that they can be used as chemical biomarkers of marine salt.