Benzimidazolium functionalized polysulfone-based anion exchange membranes with improved alkaline stability

The stability of anion exchange membranes(AEMs) is an important feature of alkaline exchange membrane fuel cells(AEMFCs), which has been extensively studied. However it remains a real challenge due to the harsh working condition. Herein, we developed a novel type of polysulfone-based AEMs with three modified 1,2-dimethylbenzimidazoliums containing different substitutes at C4-and C7-position. The results showed that the introduction of the substitutes could obviously improve the dimensional and alkaline stabilities of the corresponding membranes. The swelling ratios of resultant AEMs were all lower than 10% after water immersion. The membrane with 4,7-dimethoxy-1,2-dimethylbenzimidazolium group exhibited the highest alkaline stability. Only 9.2% loss of hydroxide conductivity was observed after treating the membrane in 1 mol·L~(-1) KOH solution at 80 °C for 336 h. Furthermore, the density functional theory(DFT) study on the three functional group models showed that the substitutes at C4-and C7-position affected the lowest unoccupied molecular orbital(LUMO) energies of the different 1,2-dimethylbenzimidazolium groups.     

Diet variability of Mediterranean insular populations of Rattus rattus studied by stable isotope analysis

The black rat Rattus rattus is a successful colonizer that threatens native species on numerous islands. Stable isotopes of carbon and nitrogen were used to quantify the rat diet on islands off the southern French coast. Samples of rat hair and faeces and their potential food were collected on each island. The nitrogen isotopic values of invertebrates and vegetation on Riou (near Marseille) differed from the other two islands (Hyères archipelago). This was attributed to a large colony of gulls on Riou, of which rats take great advantage. A part of the observed variability was due to methodological skews: two kinds of hair gave different results and there was an effect of the season and year of sampling but inter-island differences were noticeable. In certain cases, the food source value from plants and invertebrates could supply the total food needs of rats as there was no evidence of consumption of eggs, chicks or birds.     

Synthesis of allocolchicines using sequential ring-closing enyne metathesis-Diels-Alder reactions

New allocolchinoids having functionality in the C ring at position C10 or C11 have been synthesized using the enyne ring-closing metathesis (RCM) reaction for construction of the seven-membered ring and a Diels-Alder-aromatization sequence for the elaboration of the aromatic ring C. [reaction: see text].     

Improving the high variable bioavailability of griseofulvin by SEDDS

To enhance the dissolution and oral absorption of poorly water-soluble griseofulvin (GF), self-emulsifying drug delivery system (SEDDS) composed of oil, surfactant and cosurfactant for oral administration of griseofulvin was formulated, and its physicochemical properties and pharmacokinetic parameters were evaluated. The solubility of griseofulvin was further improved by the addition of hydrochloric acid. Droplet size of griseofulvin emulsion was kept constant both in simulated gastric fluid without pepsin and simulated intestinal fluid throughout 12 weeks incubation period. Griseofulvin in the SEDDS rapidly dissolved in different dissolution media. This was not the case for the commercial GRIS-PEG tablets. In different fed diet groups, AUC 0-->24 h, Cp max, and T max of griseofulvin after oral administration of SEDDS in rats were comparable to those after oral dose of GRIS-PEG tablet. Although, in fed lipidic diet group, the mean AUC and Cp max after oral administration of GRIS-PEG in rats were 1.28 and 1.15 fold higher, respectively, compared with those of SEDDS, these have not shown to be significantly different. These results demonstrate that the SEDDS of griseofulvin composed of Capmul GMO-50, Poloxamer and Myvacet 9-45 greatly enhanced the dissolution of griseofulvin (without ultramicronisation). However, food intake effect on the bioavailability of griseofulvin has remained. Thus, this system may provide a useful dosage form for oral water-insoluble drugs which have problems in their dissolution.     

Influence of consanguinity on the pattern of familial aggregation of congenital cardiovascular anomalies in an outpatient population: studies from the eastern province of Saudi Arabia

BACKGROUND: Familial aggregation of congenital heart disease (CHD) has been well described in different populations, in particular those with a high consanguinity rate. Extensive genetic study of affected families has improved the understanding of basic genetics of different cardiac lesions. OBJECTIVE: To identify the role of consanguinity as a risk factor among familial cases of CHD in a stable outpatient population of a tertiary care center in the Eastern Province of Saudi Arabia. METHODS: All familial cases of CHD seen over 5 years (1996-2000) in the Division of Pediatric Cardiology were identified. The presence or absence of parental consanguinity (first cousin marriage) was defined in each of these families. RESULTS: Ninety-three cases were identified in 37 families. Twenty-three (62%) families resulted from consanguineous marriages. In 4 families where there were 2 marriages, the affected children came from the consanguineous marriage in 3 of these families. Discordant lesions occur only among non-consanguineous cases, while all consanguineous cases were concordant. Five sets of twins of the same sex (one set are monozygotic by DNA analysis) occurred among consanguineous marriages, in 3 of these both twins were affected with the same disease. Affected parents were seen in 2 families with consanguineous marriage and none in the non-consanguineous marriages. The prevalence of dilated cardiomyopathy was much higher among consanguineous cases (26 vs. 2). CONCLUSIONS: Familial aggregation of congenital heart disease is common in our population. Consanguinity is common in these families, and the distribution of congenital heart disease differs in this subgroup compared to the rest of the familial cases. Further genetic studies of these families may help to shed more light on basic genetics and the specific pathogenetic mechanisms involved.     

A new approach to obtain Kevlar-49 from PET waste bottles

Non-biodegradable polyethylene terephthalate (PET) bottles have attracted increasing attention due to environmental concern in today’s world. In order to reduce the amount of solid wastes generated and the dependency on fossil resources, a new approach has been conducted to prepare Kevlar-49 from PET waste bottles. Terephthalic acid, the main raw material used for preparation of Kevlar, was regenerated from PET waste bottles via subjection to a saponification process, whereas p-phenylenediamine was prepared from PET waste bottles via the Hoffmann rearrangement method. Kevlar was synthesized from the reaction of terephthalic acid and p-phenylenediamine by polycondensation reaction. The structures of terephthalic acid, p-phenylenediamine and Kevlar were characterized by FT-IR, ¹H NMR, ¹³C NMR, and elemental analysis (CHN). In this study, thermogravimetric analysis and differential scanning calorimetry, X-ray diffraction (XRD), as well as the mechanical properties (tensile strength, modulus, and percentage elongation at break) of the synthesized Kevlar-49, were compared with commercial Kevlar-49, prepared from the same raw materials, for better understanding of their properties.     

Ridge directional singular points for fingerprint recognition and matching

In this paper, a new approach to extract singular points in a fingerprint image is presented. It is usually difficult to locate the exact position of a core or a delta due to the noisy nature of fingerprint images. These points are the most widely used for fingerprint classification and matching. Image enhancement, thinning, cropping, and alignment are used for minutiae extraction. Based on the Poincaré curve obtained from the directional image, our algorithm extracts the singular points in a fingerprint with high accuracy. It examines ridge directions when singular points are missing. The algorithm has been tested for classification performance on the NIST‐4 fingerprint database and found to give better results than the neural networks algorithm. Copyright © 2005 John Wiley & Sons, Ltd.     

Two Questions on Products of Toeplitz Operators on the Bergman Space

The zero product problem and the commuting problem for Toeplitz operators on the Bergman space over the unit disk are some of the most interesting unsolved problems. For bounded harmonic symbols these are solved but for general bounded symbols it is still far from being complete. This paper shows that the zero product problem holds for a special case where one of the symbols has certain polar decomposition and the other is a general bounded symbol. We also prove that the commutant of T_z+[`(z)]T_z+\bar{z} is sum of powers of itself.     

Second moments of ESR signals from poly(p-phenylene) and the deuterated analog

The second moments of the ESR signals obtained from poly(p-phenylene) (PPP) and deuterated PPP were measured at 9.5 and 35 GHz. The theoretical and experimental contributions to the second moments were considered. It is shown that for deuterated PPP, deuteron hyperfine splitting makes a negligible contribution to the observed second moment. The proton hyperfine contributions to the second moments of the radical species in PPP and p-sexiphenyl were estimated and it was concluded that the unpaired electron was delocalized over only 2-4 phenylene units. A rationale is offered in terms of polarons present as defects in the PPP chains.