Comparison of the sensitivity of 11 crosslinked hyaluronic acid gels to bovine testis hyaluronidase

Crosslinked hyaluronan gels are used in various applications where their stability is a prerequisite. The sensitivity of such gels to hyaluronidase can be determined as an index of stability by several approaches: chromatography, electrophoresis, and viscometry. We describe here a test based on the colorimetric determination of the N-acetyl-d-glucosamine released by hyaluronidase in standardized conditions. The sensitivities to bovine testicular hyaluronidase of 11 different gels used to fill skin wrinkles (Restylane; Perlane; Juvéderm 18, 24, 24HV, 30, and 30HV; Surgiderm 18, 24XP, 30, and 30XP) were compared.The method was reproducible, easy to perform, not time-consuming and allowed us to demonstrate that the sensitivity to testicular hyaluronidase was dependent on the degree of crosslinking of the gels and also on their monophasic/biphasic nature. Under our conditions, Surgiderm 30, 24XP and 30XP were the most resistant gels.We propose to retain the hyaluronidase test to predict the in situ stability of a crosslinked gel used to fill skin wrinkles.     

Xenicane Diterpenes Revisited: Thermal (E)→(Z) isomerization and conformational motions. A unifying picture

Kinetic and equilibrium studies show that typical xenicanes such as dictyolactone ( 1 ) and 4-hydroxydictyolactone ( 3 ) undergo slow conformation medium-ring flipping between the predominant trans-( 1a or 3a ; Me(20) trans to H–C(3)) and the minor cis-conformers ( 1b or 3b ; Me(20) cis to H–C(3); see Scheme 1). The formation of the latter is inhibited in heterocyclic-ring-opened congeners such as 18-acetoxy-4-hydroxydictyo-19-al ( 7 ). Molecular-mechanics calculations suggest that typical-xenicane cis-conformers are disfavoured by mainly C(4)–C(5) torsional strain. This is confirmed by the observation of two sizably populated cis-and trans-conformers for the unnatural 4-oxoxenicanes 10–12 . Unusually facile thermal (E)→(Z) isomerization of xenicanes 1,3,10–12 , and 7 is also observed (→ 13–17 and 9 , resp.; Scheme 3), reflecting great strain relief in the transition state. Conflicting results in the literature now fit into this scheme which provides a basis for unravelling recognition phenomena with these biologically active systems.     

On the T∘-slices of a finite group

A slice $(G,S)$ of finite groups is a pair consisting of a finite group G and a subgroup S of G. In this paper, we show that some properties of finite groups extend to slices of finite groups. In particular, by analogy with B-groups, we introduce the notion of $T^{°}$-slice, and show that any slice of finite groups admits a largest quotient $T^{°}$-slice.     

Analysis of Travel Time Distributions for Uncertainty Propagation in Channelized Porous Systems

Transport in Porous Media - In the context of stochastic two-phase flow in porous media, one is often interested in estimating the statistics of fluid saturations in the reservoir. In this work, we...     

On the electronic structure and hydrogen evolution reaction activity of platinum group metal-based high-entropy-alloy nanoparticles

We report the synthesis of high-entropy-alloy (HEA) nanoparticles (NPs) consisting of five platinum group metals (Ru, Rh, Pd, Ir and Pt) through a facile one-pot polyol process. We investigated the electronic structure of HEA NPs using hard X-ray photoelectron spectroscopy, which is the first direct observation of the electronic structure of HEA NPs. Significantly, the HEA NPs possessed a broad valence band spectrum without any obvious peaks. This implies that the HEA NPs have random atomic configurations leading to a variety of local electronic structures. We examined the hydrogen evolution reaction (HER) and observed a remarkably high HER activity on HEA NPs. At an overpotential of 25 mV, the turnover frequencies of HEA NPs were 9.5 and 7.8 times higher than those of a commercial Pt catalyst in 0.05 M H₂SO₄ and 1.0 M KOH electrolytes, respectively. Moreover, the HEA NPs showed almost no loss during a cycling test and were much more stable than the commercial Pt catalyst. Our findings on HEA NPs may provide a new paradigm for the design of catalysts.

RuRhPdIrPt high-entropy-alloy nanoparticles with a broad and featureless valence band spectrum show high hydrogen evolution reaction activity.     

Interaction between hydrophilic drug and α-cyclodextrins: physico-chemical aspects

The aim of the study was to evaluate if the complexation of a hydrophilic molecule by cyclodextrins is possible. Cyclodextrins (CDs) are hydrophilic cone shaped molecules, which are used as vehicles able to include organic molecules. Because of the presence of hydroxy groups (OH) outside of the molecule, cyclodextrins are not predisposed to include hydrophilic drugs. They are therefore used to improve the solubility of poor water-soluble molecules. In order to evaluate if the complexation of a hydrophilic molecule by cyclodextrins is possible, lyophilized complexes of cysteamine hydrochloride with α-cyclodextrins (α-CD) have been realized. Six analytical techniques (High performance Liquid Chromatography coupled to UV detection, Thin-Layer Chromatography, Fourier Transform Infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Mass Spectrometry (SM) and Proton Nuclear Magnetic Resonance (NMR-NOESY spectra)) were used in order to characterize the interaction between the drug and the α-CD. The realization of complex between a cyclodextrin and a water-soluble drug seems feasible. In the case of a hydrophilic molecule, the complexation is not obtained by inclusion of the drug in the cyclodextrin, but by binding to the outside of the cone. This “external complexation” is however sufficient to improve some features of the molecule, such as organoleptic features, and to modifiy measurable parameters (FT-IR, DSC, SM and NMR-NOESY spectra).     

Uncertainty Propagation for Compositional Flow Using a Probability Distribution Method

Transport in Porous Media - The paper presents a novel approach for uncertainty propagation in multicomponent two-phase displacements. This approach originates from and extends the frozen...     

Bounds for Asian basket options

In this paper we propose pricing bounds for European-style discrete arithmetic Asian basket options in a Black and Scholes framework. We start from methods used for basket options and Asian options. First, we use the general approach for deriving upper and lower bounds for stop-loss premia of sums of non-independent random variables as in Kaas et al. [Upper and lower bounds for sums of random variables, Insurance Math. Econom. 27 (2000) 151–168] or Dhaene et al. [The concept of comonotonicity in actuarial science and finance: theory, Insurance Math. Econom. 31(1) (2002) 3–33]. We generalize the methods in Deelstra et al. [Pricing of arithmetic basket options by conditioning, Insurance Math. Econom. 34 (2004) 55–57] and Vanmaele et al. [Bounds for the price of discrete sampled arithmetic Asian options, J. Comput. Appl. Math. 185(1) (2006) 51–90]. Afterwards we show how to derive an analytical closed-form expression for a lower bound in the non-comonotonic case. Finally, we derive upper bounds for Asian basket options by applying techniques as in Thompson [Fast narrow bounds on the value of Asian options, Working Paper, University of Cambridge, 1999] and Lord [Partially exact and bounded approximations for arithmetic Asian options, J. Comput. Finance 10 (2) (2006) 1–52]. Numerical results are included and on the basis of our numerical tests, we explain which method we recommend depending on moneyness and time-to-maturity.     

Moment matching approximation of Asian basket option prices

In this paper we propose some moment matching pricing methods for European-style discrete arithmetic Asian basket options in a Black & Scholes framework. We generalize the approach of [M. Curran, Valuing Asian and portfolio by conditioning on the geometric mean price, Management Science 40 (1994) 1705-1711] and of [G. Deelstra, J. Liinev, M. Vanmaele, Pricing of arithmetic basket options by conditioning, Insurance: Mathematics & Economics 34 (2004) 55-57] in several ways. We create a framework that allows for a whole class of conditioning random variables which are normally distributed. We moment match not only with a lognormal random variable but also with a log-extended-skew-normal random variable. We also improve the bounds of [G. Deelstra, I. Diallo, M. Vanmaele, Bounds for Asian basket options, Journal of Computational and Applied Mathematics 218 (2008) 215-228]. Numerical results are included and on the basis of our numerical tests, we explain which method we recommend depending on moneyness and time-to-maturity.