Structure−Activity Relationships of Cinnamate Ester Analogues as Potent Antiprotozoal Agents

Protozoal infections are still a global health problem, threatening the lives of millions of people around the world, mainly in impoverished tropical and sub-tropical regions. Thus, in view of the lack of efficient therapies and increasing resistances against existing drugs, this study describes the antiprotozoal potential of synthetic cinnamate ester analogues and their structure-activity relationships. In general, Leishmania donovani and Trypanosoma brucei were quite susceptible to the compounds in a structure-dependent manner. Detailed analysis revealed a key role of the substitution pattern on the aromatic ring and a marked effect of the side chain on the activity against these two parasites. The high antileishmanial potency and remarkable selectivity of the nitro-aromatic derivatives suggested them as promising candidates for further studies. On the other hand, the high in vitro potency of catechol-type compounds against T. brucei could not be extrapolated to an in vivo mouse model.     

Incorporation of Very Insoluble Monomers in Waterborne Coatings

The benefits of polymerizing very insoluble monomers in aqueous media, avoiding the use of energy‐intensive procedures, by implementing two novel synthesis techniques based on the emulsifier combination in emulsion polymerization and on miniemulsification by phase inversion temperature are investigated. The performance of standalone polymers consisting of monomers, namely lauryl methacrylate, isobornyl acrylate, and 1H,1H,2H,2H‐perfluorodecyl acrylate, and of formulated binders with these monomers incorporated either through blending or in situ polymerization, is evaluated with special emphasis on their water‐barrier properties (e.g., uptake, whitening, immersion, and vapor resistance) and on their chemical resistance. The performance of the standalone polymers is found to be similar to that of polymers prepared by high‐shear miniemulsion polymerization, while the performance of the formulated binders is generally superior to a commercial coating formulation based on a binder recommended for water resistance.     

Multilayer Stacked Low‐Temperature‐Reduced Graphene Oxide Films: Preparation,Characterization, and Application in Polymer Memory Devices

Highly reduced graphene oxide (rGO) films are fabricated by combining reduction with smeared hydrazine at low temperature (e.g., 100 °C) and the multilayer stacking technique. The prepared rGO film, which has a lower sheet resistance (≈160–500 Ω sq⁻¹) and higher conductivity (26 S cm⁻¹) as compared to other rGO films obtained by commonly used chemical reduction methods, is fully characterized. The effective reduction can be attributed to the large “effective reduction depth” in the GO films (1.46 µm) and the high C1s/O1s ratio (8.04). By using the above approach, rGO films with a tunable thickness and sheet resistance are achieved. The obtained rGO films are used as electrodes in polymer memory devices, in a configuration of rGO/poly(3‐hexylthiophene) (P3HT):phenyl‐C61‐butyric acid methyl ester (PCBM)/Al, which exhibit an excellent write‐once‐read‐many‐times effect and a high ON/OFF current ratio of 10⁶.     

Absolute quantification of perfusion using dynamic susceptibility contrast MRI: pitfalls and possibilities

Absolute quantification of cerebral blood flow, cerebral blood volume and mean transit time is desirable in the determination of tissue viability thresholds and tissue at risk in acute ischaemic stroke, as well as in cases where a global reduction in cerebral blood flow is expected, for example, in patients with dementia or depressive disorders. Absolute values are also useful when comparing sequential examinations of tissue perfusion parameters, for example, in the monitoring and follow-up of various kinds of therapy. Regardless of the method employed, a number of assumptions and approximations must be made to obtain absolute measures of perfusion. Furthermore, the different stages of data acquisition and processing are associated with various degrees of uncertainty. In this review, the problems of particular relevance to absolute quantification of cerebral perfusion parameters using dynamic susceptibility contrast magnetic resonance imaging are discussed, and possible solutions are outlined.     

Determination of horizontal permeability from the elliptical flow of horizontal wells using conventional analysis

Besides the regular four flow regimes normally seen during a pressure test of horizontal wells, it is possible, under special circumstances, to observe such additional flow regimes as spherical, hemi-radial, linear (reservoir channel) and elliptical. The last flow regime is characterized by a slope of 0.36 of the pressure derivative curve and occurs between the early linear flow and the pseudo-radial flow periods. This may have been overlooked in horizontal well test analysis, because it is often masked by the other flow regimes, unless the conditions are just right.The elliptical flow regime has been previously mentioned by very few researchers, Issaka et al. [Issaka, M.B., Zaoral, K., Ambastha, A.K. and Mattar, L., 2000: “Determination of Horizontal Permeability Anisotropy from Horizontal Well Tests,” SPE Saudi Arabia Section Technical Symposium, Dhahran, Saudi Arabia, 21–23 October.], Chacon et al. [Chacon, A., Djebrouni, A. and Tiab, D., 2004. “Determining the Average Reservoir Pressure from Vertical and Horizontal Well Test Analysis Using Tiab's Direct Synthesis Technique”. SPE 88619, Proceedings, SPE Asia Pacific Oil & Gas Conf. & Exhibition, Perth, Australia, 18–20 October.] and Escobar et al. [Escobar, F.H., Munoz, O.F., and Sepulveda, J.A., 2004. “Horizontal Permeability Determination from the Elliptical Flow Regime for Horizontal Wells”. CT&F — Ciencia, Tecnología y Futuro. Vol. 2 Num. 5. p. 83–95. Dec.]. A methodology for its characterization has been also introduced using the pressure derivative concept and TDS technique [Escobar, F.H., Munoz, O.F., and Sepulveda, J.A., 2004. “Horizontal Permeability Determination from the Elliptical Flow Regime for Horizontal Wells”. CT&F — Ciencia, Tecnología y Futuro. Vol. 2 Num. 5. p. 83–95. Dec.]. However, conventional analysis for the characterization of this has not yet been reported in the literature. This flow regime is very useful to estimate the horizontal permeability, especially, when the pseudo-radial flow is very short or unclear, or simply, when it is desired to verify that estimation.In this paper, equations for the estimation of the horizontal permeability and elliptical skin factor are developed for both gas and oil horizontal wells, so that the mentioned parameters can be estimated, respectively, from the slope and intercept of linear plot of pressure versus time to the power 0.36. The equations were successfully tested with two field examples previously worked in the literature.     

Polyphenylene Dendrimer‐Templated In Situ Construction of Inorganic–Organic Hybrid Rice‐Shaped Architectures

A novel dendrimer‐templating method for the synthesis of CuO nanoparticles and the in situ construction of ordered inorganic–organic CuO–G2Td(COOH)₁₆rice‐shaped architectures (RSAs) with analogous monocrystalline structures are reported. The primary CuO nanoparticles are linked by the G2Td(COOH)₁₆ dendrimer. This method provides a way to preserve the original properties of primary CuO nanoparticles in the ordered hybrid nanomaterials by using the 3D rigid polyphenylene dendrimer (G2Td(COOH)₁₆) as a space isolation. The primary CuO nanoparticles with diameter of (6.3 ± 0.4) nm are synthesized via four successive reaction steps starting from the rapid reduction of Cu(NO₃)₂ by using NaBH₄ as reducer and G2Td(COOH)₁₆ as surfactant. The obtained hybrid CuO–G2Td(COOH)₁₆ RSA, formed in the last reaction step, possesses a crystal structure analogous to a monocrystal as observed by transmission electron microscopy(TEM). In particular, the formation process of the RSA is monitored by UV–vis, TEM, and X‐ray diffraction. Small angle X‐ray scattering and Fourier transform infrared spectroscopy are used to investigate the role of the dendrimer in the RSA formation process. The obtained results illuminate that Cu²⁺? COO^? coordination bonds play an indispensable role in bridging and dispersing the primary CuO nanoparticles to induce and maintain the hybrid RSA. More importantly, the RSA is retained through the Cu²⁺? COO^?coordination bonds even with HCl treatment, suggesting that the dendrimers and Cu²⁺ ions may form rice‐shaped polymeric complexes which could template the assembly of CuO nanoparticles towards RSAs. This study highlights the feasibility and flexibility of employing the peculiar dendrimers to in‐situ build up hybrid architectures which could further serve as templates, containers or nanoreactors for the synthesis of other nanomaterials.     

Enterococci with acquired vancomycin resistance in pigs and chickens of different age groups

Results of isolation of glycopeptide-resistant enterococci from fecal samples of pigs and chickens were found to differ strongly depending upon the type and age of animals and isolation technique (direct selective plate or broth enrichment). Isolations were frequent in broiler chickens and in sows but rare in layer chickens.