Sodium Chloride Molar Conductance in Different Poly(ethylene glycol)–Water Mixed Solvents

The molar conductivities of NaCl in several poly(ethylene glycol)(PEG)–water “mixed solvents” are presented as a function of the PEG content in solution. Three different PEG samples, a monodispersed one and two polydispersed ones, have been used. The comparison between the molar conductivity values in the mixed solvents and the corresponding ones in pure water shows that the only effect of PEG on the ions’ motions is an obstruction effect despite the variation of the macroscopic dielectric constant induced by PEG itself. A comparison between the molar conductivities and the corresponding mutual main diffusion coefficients shows a tight correlation between the two quantities. This correlation is possible only in the absence of electrostatic effects due to the presence of PEG.     

Acidic Monosaccharides become Incorporated into Calcite Single Crystals**

Carbohydrates, along with proteins and peptides, are known to represent a major class of biomacromolecules involved in calcium carbonate biomineralization. However, in spite of multiple physical and biochemical characterizations, the explicit role of saccharide macromolecules (long chains of carbohydrate molecules) in mineral deposition is not yet understood. In this study, we investigated the influence of two common acidic monosaccharides (MSs), the two simplest forms of acidic carbohydrates, namely glucuronic and galacturonic acids, on the formation of calcite crystals in vitro. We show here that the size, morphology, and microstructure of calcite crystals are altered when they are grown in the presence of these MSs. More importantly, these MSs were found to become incorporated into the calcite crystalline lattice and induce anisotropic lattice distortions, a phenomenon widely studied for other biomolecules related to CaCO₃ biomineralization, but never before reported in the case of single MSs. Changes in the calcite lattice induced by MSs incorporation were precisely determined by high-resolution synchrotron powder X-ray diffraction. We believe that the results of this research may deepen our understanding of the interaction of saccharide polymers with an inorganic host and shed light on the implications of carbohydrates for biomineralization processes.     

Fabrication of hollow porous PLGA microspheres for controlled protein release and promotion of cell compatibility

This letter reports on the fabrication of hollow,porous and non-porous poly(D,L-lactide-co-glycolide) (PLGA) microspheres(MSs) for the controlled release of protein and promotion of cell compatibility of tough hydrogels.PLGA MSs with different structures were prepared with modified double emulsion methods,using bovine serum albumin(BSA) as a porogen during emulsification.The release of the residual BSA from PLGA MSs was investigated as a function of the MS structure.The hollow PLGA MSs show a faster protein release than the porous MSs,while the non-porous MSs have the slowest protein release.Compositing the PLGA MSs with poly(vinyl alcohol)(PVA) hydrogels promoted chondrocyte adhesion and proliferation on the hydrogels.     

Measurement of small quantities: further observations on Bayesian methodology

This article discusses the measurement of the sum of small positive quantities each estimated in separate analyses. It extends criticism recently given of ‘objective Bayesian’ methodology (Accred Qual Assur 15:181–188, 2010) and identifies two troublesome effects: the inherent bias in an analysis for a single quantity is compounded when the measurand is the sum of such quantities, and the precaution of overestimating measurement variability can actually make the resulting interval of measurement uncertainty less reliable! Unacceptable results are obtained. A cause of this behavior is identified, and a distinction between ‘objective’ and ‘subjective’ Bayesian statistics is discussed.     

Fluorescence of Pyranine in Sol-Gel Based Silica and Hybrid Thin Films

The sensitivity of the pyranine fluorescence to protonation/deprotonation is used to follow modifications in cured sol-gel thin films. The acid concentration in the sol-gel solution is varied for TEOS-based coatings and a series of organically modified silanes Si(OR)₃R’ are added to the TEOS solution. The concentration of the organically modified silane is varied as well as the chain length of the alkylgroup (R’). The stationary fluorescence measurements show that the equilibrium between the protonated and the deprotonated form of pyranine changes depending on the type of silica matrix. The deprotonated form is dominant in the cured SiO₂ films and the protonation/deprotonation ratio of pyranine is constant for the different acid concentrations used. The protonated form becomes dominant as the concentration of Si(OR)₃R’ is increased and as the alkyl chain length (R’) of the organically modified silanes is augmented. Emission anisotropy measurements of pyranine in the same coatings show that the rotational freedom of the molecule changes due to modifications in the cages for the TEOS-based coatings. These modifications are produced by the acid concentration used to prepare the coatings. An increase in the rotational freedom of pyranine is observed in the TEOS-Si(OR)₃R’ systems.     

Preparation of Albumin Microspheres Grafted Galactose Residues Through Polyethylene-Glycol Spacers,Release Behavior of 5-Fluorouracil from Them,and Their Lectin-Mediated Aggregation

Small-sized albumin gel microspheres, MSs, containing 5-fluorouracil (5FU) with targeting moieties on their surfaces (average diameter: 1.5 μm) were prepared by the glutaraldehyde crosslinking method and suspension technique. Since galactose is known to interact specifically with the asialoglycoprotein receptor on hepato-cyte, the galactose residues were introduced on the surface of MSs as the targeting moieties for hepatoma through polyethylene glycol (PEG) spacers. PEG spacers were employed to depress the immu-nogenicity of albumin, to keep the mobility of the galactose residues, and to heighten the distributive stability of the MSs in aqueous solution. It was confirmed by ESC A analysis that the PEG chains were introduced onto the surfaces of MSs. The amount of galactose residues introduced to MS were estimated to be 0.013 wt%. The intra-MSs aggregation was observed by the addition of Ricinus Communis Agglutinin I (RCA120) into the MS suspension, and then the aggregation of MSs was dissociated by addition of free lactose. Moreover, by incubation of the MSs with human hepatoma HLE cells, the phenomena of MS's specific binding onto HLE cell surfaces and phagocytosis of MSs by HLE cells were observed. These results suggested that the galactose residues on the surface of MSs were recognized with the galactose receptors on hepatoma cell surfaces. The release rate of 5FU from MSs was investigated in vitro in physiological saline at 37OC. About 90% of encapsulated 5FU were found to be released from MSs through incubation for 8 h.     

Klein on the origin of the concept of chemical compound

Ursula Klein has argued that Geoffroy’s table of chemical affinities, published in 1718, marked the emergence of the concepts of chemical compound and chemical combination central to chemistry. In this paper her position is summarised and then modified to render it immune to criticism that has been levelled against it. The essentials of Geoffroy’s chemistry are clarified and adapted to Klein’s picture by way of a detailed comparison of it with Boyle’s corpuscular chemistry that proceeded Geoffroy’s by over half a century. The idea that Geoffroy’s notion of chemical combination marked a significant turning point in the emergence of modern chemistry is defended against the charge that it is Whiggish.     

Ultrahydrophobic aluminium surfaces: properties and EIS measurements of different oxidic and thin-film coated states

Firstly, the contribution summarises important results of the work dedicated to the formation of ultrahydrophobic aluminium surfaces. This treatment comprises sulphuric acid anodisation under intensified temperature and current density conditions (‘SAAi’) as well as subsequent chemical modification (‘C’). The usual sulphuric acid anodisation (‘SAAu’) was included for comparison. These various states were examined by electrochemical impedance spectrometry (EIS) to derive typical EIS-related features, especially for the ultrahydrophobic states compared to the anodised surfaces. Based on well-defined spectra types, modelling yielded results, preferentially with regard to the nano-porosity of the oxidic layers. EIS measurements allowed the conclusion that the original nano-porosity underwent specific changes due to the chemical modification variants employed. The chances of EIS predicting the stability of the ultrahydrophobically modified systems are critically assessed on the background of standardised weathering tests.     

Proposed guidelines for the final review of measurement results in the clinical laboratory

The standard ISO 15189 requires a systematic review of results of clinical laboratory examinations, but it does not provide details on how to carry out such a review. In this article, the Catalan Association of Clinical Laboratory Sciences proposes a guide for this review of patients’ clinical laboratory results pertaining to rational or difference scales (‘quantitative values’). The review process is based on the so-called plausibility control, which may be defined as the set of procedures used to decide if a measurement result is valid or not according to established clinical and biological criteria, considering four variables: (1) alert limits; (2) consistency with the previous result, if any; (3) consistency with other results obtained from the same sample, if any; and (4) consistency with the diagnosis (presumed or confirmed) or, when it is not known, the origin of the request, though these last criteria are generally very weak and the derived decisions may be scantly reliable. This guide has been prepared on the behalf of the Technical Committee of the Catalan Association for Clinical Laboratory Sciences. Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board and the Publisher.     

Consequences of Holba-Šesták equation

It was proved on the basis of Holba-Šesták equation (1972) that the one is very interesting point of view to define the relative rate of reaction/process. Thereby, the assumption about interconnection between three-parametric equation and thermodynamic condition determined by equilibrium conversion degree in given temperature, is strengthened. Further considerations, still based on analysis of the inequality, made possible proposition of thesis about maximal rate of reaction/process in dynamic conditions in relation to modified van’t Hoff’s isobar (equation).     

Simple principles for metrology in chemistry: identifying and counting

We examine the problem of quantitative chemical measurement for well-identified substances, discuss the quantity called ‘amount of substance’, the means of expressing it, and its physical SI unit the mole. The everyday quantity which is a number of entities may be measured by the performance of two operations (identification and counting), the results of which may be communicated with two items of information (their name and the number of entities). We distinguish nominal, ordinal, interval and ratio scales of measurement and apply these to counting, referring to ordinal and cardinal numbers and Helmholtz’ analysis of measurement. Counting may be by direct serial numeration, direct parallel numeration, or comparative numeration. We discuss the limitations of serial numeration, the possibilities of parallel numeration, and the advantages of comparative numeration where a unit for counting in multiples (such as the analyst’s mole) may be used to define a scale on which equal numbers of objects correspond to equal values of some other physical quantity. We conclude that the numeration of very large numbers of objects is readily achieved but with unavoidable uncertainty, using operations which compare numbers of entities either to numbers of other entities or to some other quantity which accurately models numbers of entities.     

Gemini Surfactants Templated Mesoporous Silica Microparticles: from Solid to Hollow Mesoporous Spheres

We synthesized a series of mesoporous silica microparticles (MSs) using cationic gemini surfactants C_14–2‐n (n = 2, 6, 10, 14) as templates. The porous structures and pore size of these MSs can be tuned by varying the length of alkyl chain in gemini surfactant templates. These MSs showed effective doxorubicin (DOX) loading and a pH‐responsive drug release characteristics. These results indicate that the MSs, especially the hollow mesoporous silica nanoparticles, have great potential for biomedical applications.     

Suppression of Pulmonary Tumor Promotion and Induction of Apoptosis by <Emphasis Type="Italic">Crocus sativus</Emphasis> L. Extraction

Crocus sativus L., commonly known as saffron, is the raw material for one of the most expensive spice in the world, and it has been used in folk medicine for centuries. We investigated the potential of the ethanolic extract of saffron to induce cytotoxic and apoptosis effects in carcinomic human alveolar basal epithelial cells (A549), a commonly used cell culture system for in vitro studies on lung cancer. The cells were cultured in Dulbecco’s modified Eagle’s medium with 10% fetal bovine serum treated with different concentrations of the ethanolic extract of saffron for two consecutive days. Cell viability was quantitated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. Apoptotic cells were determined using annexin V–fluorescein isothiocyanate by flow cytometry. Saffron could decrease the cell viability in the malignant cells as a concentration- and time-dependent manner. The IC₅₀ values against the A549 cell lines were determined as 1,200 and 650 μg/ml after 24 and 48 h, respectively. Saffron-induced apoptosis of the A549 cells in a concentration-dependent manner, as determined by flow cytometry histogram of treated cells that induced apoptotic cell death, is involved in the toxicity of saffron. It might be concluded that saffron could cause cell death in the A549 cells, in which apoptosis plays an important role. Saffron could also be considered as a promising chemotherapeutic agent in lung cancer treatment in future.     

Identification of unknown irradiated nuclear fuel through its fission product content

A procedure is demonstrated, through a simulation study, for the determination of the origin of unknown spent nuclear fuel, an important and challenging task in nuclear forensics. The procedure is an isotopic fingerprinting method relying on the fission product content of the unknown. The ‘unknown’ nuclear material is represented by the spent nuclear fuel of known origin in order to demonstrate the method and verify its predictive capabilities. The method is based on the comparison of the fission product compositions of the ‘unknown’ material and simulated known spent fuels from a range of commercial nuclear power stations using the multivariate statistical technique of factor analysis. Then, the provenance of the ‘unknown’ spent fuel is the commercial fuel with which it exhibits the highest similarity with respect to the fission product content.     

The application of electroanalytical methods to the analysis of phase transitions during intercalation of ions into electrodes

Mechanisms of first-order phase transition induced by electrochemical intercalation of Li ions into composite graphite electrode are studied both theoretically, in the framework of lattice gas models, and experimentally, by a combination of electroanalytical techniques, such as cyclic voltammetry, potentiostatic intermittent titration (PITT), galvanostatic intermittent titration (GITT), and electrochemical impedance spectroscopy (EIS). From the analysis of the mismatch between the accessible phase-transition rate constants and the characteristic time windows for various electroanalytical methods, we conclude that only a combined application of these techniques provides sufficient, self-consistent information on the mechanisms of phase transitions in graphite electrodes. The advantages and disadvantages in using these techniques are discussed. PITT with a small potential step is the most appropriate tool for measuring the entire sequence of rate-determining steps of phase transitions as a function of time. The latter technique can be conveniently used for quantitative analysis of slow nucleation and the growth of new phases in the bulk of the old one, followed by the coalescence of nuclei and the formation of phase boundaries between the coexisting phases. The movement of this boundary into the electrode’s bulk has been properly modeled in terms of two alternative models. “Contribution to the International Workshop on Electrochemistry of Electroactive Materials (WEEM-2006), Repino, Russia, 24–29 June 2006.”     

Towards microphase separation in epoxy systems containing PEO/PPO/PEO block copolymers by controlling cure conditions and molar ratios between blocks. Part 2. Structural characterization

The influence of addition of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO–PPO–PEO) copolymers on final morphologies of modified epoxy matrices has been investigated as a function of PEO:PPO molar ratio and cure conditions by comparison with the cured epoxy blends only containing poly(ethylene oxide) (PEO) or poly(propylene oxide) (PPO) homopolymers. Atomic force microscopy (AFM) has been used to characterize structural features of blends. Whilst diglycidyl ether of bisphenol-A (DGEBA)/4,4’-diaminodiphenylmethane (DDM)/PPO system macrophase separates, the interactions between PEO and cured epoxy are responsible for miscibility of DGEBA/DDM/PEO system. Depending on PEO:PPO molar ratio, micro- or macrophase separated morphologies have been obtained for block copolymer modified epoxy matrices. Moreover, the influence of both copolymer content and cure temperature on final morphologies has also been investigated by both experimental and theoretical analysis.     

Pyrolysis-GC/MS and TG/MS study of mediated laccase biodelignification of Eucalyptus globulus kraft pulp

Biobleaching studies using laccase mediator system (LMS) were carried out, under optimized conditions, on two unbleached Eucalyptus globulus kraft pulps, one produced by conventional way, with kappa number of 16.1, and another with kappa number of 14.5, obtained by modified kraft procedure with a high liquor/wood ratio and with black liquor replacement in the middle of the cooking. The pulp properties before and after LMS and alkaline extraction were evaluated in terms of kappa number, hexeneuronic acid content, viscosity, brightness and acid insoluble lignin content.The original milled wood sample and the kraft pulps were characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetry/mass spectrometry (TG/MS). Eucalypt wood lignin produces guaiacol and syringol derivatives during pyrolysis. These lignin products can be detected with high sensitivity using the selected ion chromatograms even in the bleached pulp of low lignin content (about 0.5%). Py-GC/MS revealed that the lignin moieties were similarly altered during biobleaching as during pulping, which is exemplified by the preferential removal of aldehyde groups from the alkyl side groups. Semi-quantitative analysis of the pyrograms indicates that the lignin content of the biobleached pulps is reduced by about half in comparison with the unbleached pulps. The TG/MS results show that the hemicellulose content of wood was strongly modified during pulping resulting in higher thermal stability.