Investigation of the Interaction Between Lidocaine and the Components of Hyaluronic Acid Using Frontal Analysis Continuous Capillary Electrophoresis

The frontal analysis continuous capillary electrophoresis (FACCE) technique was used for the characterziation of the interaction between lidocaine-HCl (Lido) and components of Na-hyaluronic acid (HA). N-Acetylglucosamine (GlcNAc) and glucuronic acid (GluA) were the components of Na-hyaluronic acid. For the investigations fused silica capillaries were used. The FACCE method was compared to affinity capillary electrophoresis (ACE). The association constants between lidocaine-HCl and the components of Na-hyaluronic acid were determined using FACCE. It was observed that only an interaction between Lido and GluA exhibited. The association constant (K _lido-GluA) between Lido and GluA was 26 ± 0.3 L mol^?1.     

Distinct length modular zero-sum subsequences: A proof of Graham's conjecture

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Let S be a sequence of n nonnegative integers not exceeding n−1 such that S takes at least three distinct values. We show that S has two nonempty zero-sum subsequences with distinct lengths. This proves a conjecture of R.L. Graham. The validity of this conjecture was verified by Erd?s and Szemerédi for all sufficiently large prime n.

Video

For a video summary of this paper, please click here or visit http://www.youtube.com/watch?v=LftJj-E6aQA.     

Application of chemometrics and FTIR for determination of viscosity index and base number of motor oils

The viscosity index (VI) and the base number (BN) of motor oils are the most important parameters to be measured in order to assess their performance and service time. Both parameters were simply obtained for virgin and recycled motor oil samples using multivariate calibration based on the FTIR data. Analysis showed that the PLS-1 has outperformed CLS and PCR for the oil parameters prediction. Five and four PLS-1 latent variables were found optimum to obtained the VI and the BN from the FTIR data; respectively. With high accuracy (99-102%) and precision (3-11%), the BN could be determined over the range 4.57-16.45 mg KOH g⁻¹ and the VI over the range 96-153. The outputs of the PLS-1 were found comparable to those obtained by the expensive and time-consuming ASTM methods. This developed method is highly recommended for quick monitoring of the motor oil quality parameters.     

Encapsulation of essential oils within a polymeric liposomal formulation for enhancement of antimicrobial efficacy

Essential oils and their constituents are known to possess antimicrobial activity; however, their inherent volatility is a limiting factor. In order to exploit the antimicrobial efficacy of essential oils, encapsulation within polymeric liposomal systems was undertaken. The liposomes were subsequently polymer-coated in order to further enhance the stability of the formulations. Essential oils distilled from Artemisia afra, Eucalyptus globulus and Melaleuca alternifolia were encapsulated into diastearoyl phosphatidylcholine and diastearoyl phosphatidylethanolamine liposomes employing a reverse phase evaporation methodology. A polyelectrolyte coating was then applied via the layer-by-layer self-deposition technique. A batch of the liposomes was polymer-coated with a 0.15%w/v chitosan solution. Using the minimum inhibitory concentration assay, the liposome-encapsulated, unencapsulated and polymer-coated liposome-encapsulated essential oils were compared in order to observe whether the antimicrobial efficacy was improved with encapsulation and polymer coating. Fractional inhibitory concentrations (FICs) were calculated in order to determine the antimicrobial interactions amongst the lipoid components, polymer coating and essential oils (synergistic, additive, indifferent and antagonistic interactions). With the exception of A. afra, microbial growth was inhibited at lower concentrations for the encapsulated formulations in comparison with the nonencapsulated oils. Synergistic to additive interactions were noted for encapsulated E. globulus (sigmaFIC values 0.25-0.45) and M alternifolia (sigmaFIC values 0.26-0.52) formulations. The addition of the polymer coating did not enhance antimicrobial activity, but owing to their positive effects on membrane stability, its presence is important as a means of extending the shelf life of these formulations. Additionally, the presence of the polymeric coating availed the essential oil at a slower rate. This investigation is a stepping stone towards the promotion of the antimicrobial use of essential oils. The added benefits are that essential oils not only provide effective antimicrobial efficacy, but also promote a "greener" consumerism. Within liposomes, they will enhance dermato-cosmetic properties and increase the marketing image of the final product.     

Fine Spectral Analysis of Isotropic Partly Elastic Neutron Transport Operators

This paper deals with spectral theory of a new class of neutron transport operators involving collision operators of the form \(K=K_{i}+K_{e}\) where \(K_{i}\) (resp. \(K_{e}\)) describes the inelastic (resp. elastic) collisions of neutrons with the host material. We give a fine analysis of their asymptotic point spectra for isotropic space homogeneous cross sections in bounded geometries. We provide a new formalism relying on spectral analysis of some non compact symmetrizable operators arising in transport theory. Additional results on essential spectra are also given.     

Solid State Deoximation with Clay SupportedAmmonium Chlorochromate: Regenerationof Carbonyl Compounds Using Microwavesin a Solventless System

Summary.  Ammonium chlorochromate adsorbed on montmorillonite K-10 rapidly regenerates carbonyl compounds from their corresponding oximes under microwave irradiation and solvent-free conditions. Received October 11, 1999. Accepted (revised) November 15, 1999     

One-pot three-component synthesis of the spiroacenaphthylene derivatives

A facile and efficient one-pot three-component synthesis of the spiroacenaphthylene derivatives was achieved, via the reaction of acenaphthequinone, malononitrile/ethylcyanoacetate and various reagents including α-methylencarbonyl compounds/enols.     

Salt effects on solute exchange in sodium dodecyl sulfate micelles

We describe the influence of sodium chloride on the rate of solute exchange in aqueous SDS micelles for a water-insoluble solute, a pyrene-containing triglyceride 1. The initially prepared solutions contained a small fraction of micelles containing two molecules of 1 and a large excess of empty micelles. These solutions showed a measurable excimer emission (of intensity I(E)) that was stable for days to weeks in the absence of added salt. Following additions of salt, I(E) decayed exponentially (rate constant, k(obs)) accompanied by an increase in pyrene monomer emission. Values of k(obs) increased strongly with ionic strength (k(obs) similar [Na(+)](4)). There was no contribution of the empty micelle concentration beyond its contribution to the sodium ion concentration. We conclude that the solute exchange involves spontaneous fragmentation of the SDS micelles into two submicelles, each bearing a molecule of 1, which then grow back to normal micelles through condensation of SDS monomers. We propose a model for the fragmentation process in which large amplitude surface fluctuations "pinch off" a subunit that becomes a submicelle. These fluctuations bring sulfate headgroups into close proximity. Fluctuations leading to fission become important only in the presence of sufficient counterion concentration to reduce the electrostatic repulsion between neighboring headgroups.     

Comprehensive classification of USA cannabis samples based on chemical profiles of major cannabinoids and terpenoids

Abstract

Different USA-origin cannabis samples were analyzed by GC-FID to quantify all possible cannabinoids and terpenoids prior to their clustering. Chromatographic analysis confirmed the presence of seven cannabinoids and sixteen terpenoids with variable levels. Among tested cannabinoids, Δ⁹-Tetrahydrocannabinol Δ⁹-THC and cannabinol CBN were available in excess amounts (1.2–8.0?wt%) and (0.22–1.1?wt%), respectively. Fenchol was the most abundant terpenoid with a range of (0.03–1.0?wt%). The measured chemical profile was used to cluster 23 USA states and to group plant samples using different unsupervised multivariate statistical tools. Clustering of plant samples and states was sensitive to the selected cannabinoids/terpenoids. Principal component analysis (PCA) indicated the importance of Δ⁹-THC, CBN, CBG, CBC, THCV, Δ⁸-THC, CBL, and fenchol for samples clustering. Δ⁹-THC was significant to separate California-origin samples while CBN and fenchol were dominant to separate Oregon-origin samples away from the rest of cannabis samples. A special PCA analysis was performed on cannabinoids after excluding Δ⁹-THC (due to its high variability in the same plant) and CBN (as a degradation byproduct for THC). Results indicated that CBL and Δ⁸-THC were necessary to separate Nevada and Washington samples, while, CBC was necessary to isolate Oregon and Illinois plant samples. PCA based on terpenoids content confirmed the significance of caryophyllene, guaiol, limonene, linalool, and fenchol for clustering target. Fenchol played a major role for clustering plant samples that originated from Washington and Nevada. k-means method was more flexible than PCA and generated three different classes; samples obtained from Oregon and California in comparison to the rest of other samples were obviously separated alone, which attributed to their unique chemical profile. Finally, both PCA and k-means were useful and quick guides for cannabis clustering based on their chemical profile. Thus, less effort, time, and materials will be consumed in addition to decreasing operational conditions for cannabis clustering.