Achieving enhanced ionic mobility in nanoporous silica by controlled surface interactions

We report a strategy to enhance the ionic mobility in an emerging class of gels, based on robust nanoporous silica micro-particles, by chemical functionalization of the silica surface. Two very different ionic liquids are used to fill the nano-pores of silica at varying pore filling factors, namely one aprotic imidazolium based (1-methyl-3-hexylimidazolium bis(trifluoromethanesulfonyl)imide, C6C1ImTFSI), and one protic ammonium based (diethylmethylammonium methanesulfonate, DEMAOMs) ionic liquid. Both these ionic liquids display higher ionic mobility when confined in functionalized silica as compared to untreated silica nano-pores, an improvement that is more pronounced at low pore filling factors (i.e. in the nano-sized pore domains) and observed in the whole temperature window investigated (i.e. from −10 to 140 °C). Solid-state NMR, diffusion NMR and dielectric spectroscopy concomitantly demonstrate this effect. The origin of this enhancement is explained in terms of weaker intermolecular interactions and a consequent flipped-ion effect at the silica interface strongly supported by 2D solid-state NMR experiments. The possibility to significantly enhance the ionic mobility by controlling the nature of surface interactions is extremely important in the field of materials science and highlights these structurally tunable gels as promising solid-like electrolytes for use in energy relevant devices. These include, but are not limited to, Li-ion batteries and proton exchange membrane (PEM) fuel cells

Sentinel hospital-based surveillance of Rotavirus diarrhea in Iran

Background. Rotavirus is the most common causes of severe, acute diarrhea during childhood and is an important cause of morbidity and mortality in developing countries. We established active hospital-based surveillance of childhood diarrhea to assess the scope of severe rotavirus disease in Iran. Methods. From May 2006 through April 2007, prospective surveillance of rotavirus diarrhea among children aged <5 years was conducted in 5 sentinel hospitals in Iran. Stool samples were tested for rotavirus using a commercially available enzyme immunoassay, and rotavirus-positive samples were genotyped using reverse-transcriptase polymerase chain reaction. Results. Of 2198 children admitted to the hospital for acute gastroenteritis, 1298 (59.1%) had stool samples test positive for rotavirus by enzyme immunoassay. Of the rotavirus episodes, 85% occurred during the first 2 years of life, with the peak prevalence of severe rotavirus disease occurring from September through January. Among the 110 rotavirus-positive samples that were genotyped, G4P[8] was the most commonly detected rotavirus genotype (30.9% of strains). Other commonly detected genotypes included P[8] with G nontypeable (21.8%), G4 with P nontypeable (13.6%), G1[P8] (10.9%), and G2[P4] (5.5%). Conclusions. Rotavirus is the most common cause of severe diarrhea in Iran, which indicates that safe and effective rotavirus vaccination in Iran is a public health priority. © 2009 by the Infectious Diseases Society of America. All rights reserved

Transforming Growth Factor β Receptor Type 1 Is Essential for Female Reproductive Tract Integrity and Function

The transforming growth factor β (TGFβ) superfamily proteins are principle regulators of numerous biological functions. Although recent studies have gained tremendous insights into this growth factor family in female reproduction, the functions of the receptors in vivo remain poorly defined. TGFβ type 1 receptor (TGFBR1), also known as activin receptor-like kinase 5, is the major type 1 receptor for TGFβ ligands. Tgfbr1 null mice die embryonically, precluding functional characterization of TGFBR1 postnatally. To study TGFBR1–mediated signaling in female reproduction, we generated a mouse model with conditional knockout (cKO) of Tgfbr1 in the female reproductive tract using anti-Müllerian hormone receptor type 2 promoter-driven Cre recombinase. We found that Tgfbr1 cKO females are sterile. However, unlike its role in growth differentiation factor 9 (GDF9) signaling in vitro, TGFBR1 seems to be dispensable for GDF9 signaling in vivo. Strikingly, we discovered that the Tgfbr1 cKO females develop oviductal diverticula, which impair embryo development and transit of embryos to the uterus. Molecular analysis further demonstrated the dysregulation of several cell differentiation and migration genes (e.g., Krt12, Ace2, and MyoR) that are potentially associated with female reproductive tract development. Moreover, defective smooth muscle development was also revealed in the uteri of the Tgfbr1 cKO mice. Thus, TGFBR1 is required for female reproductive tract integrity and function, and disruption of TGFBR1–mediated signaling leads to catastrophic structural and functional consequences in the oviduct and uterus

Elevation of the antifibrotic peptide N-acetyl-seryl-aspartyl-lysyl-proline: a blood pressure-independent beneficial effect of angiotensin I-converting enzyme inhibitors

Blockade of the renin-angiotensin system (RAS) is well recognized as an essential therapy in hypertensive, heart, and kidney diseases. There are several classes of drugs that block the RAS; these drugs are known to exhibit antifibrotic action. An analysis of the molecular mechanisms of action for these drugs can reveal potential differences in their antifibrotic roles. In this review, we discuss the antifibrotic action of RAS blockade with an emphasis on the potential importance of angiotensin I-converting enzyme (ACE) inhibition associated with the antifibrotic peptide N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP)

Towards the architectures of macromolecules: Modeling of multi-dimensional polymer chain distributions

Control of end use properties of branched polymers such as low-density Polyethylene (ldPE) produced at industrial scale is difficult at the molecular level since experimental techniques fail to detect the most decisive microstructural properties. Therefore, mathematical models are important in predicting the interesting microstructural properties of polymers. Key assumptions are related to the random scission reaction (breaking can take place in any random position of the chain), being modeled as linear or ‘topological’ scission, and to allowing/disallowing gelation. An explanation of the decisive reactions, modeling assumptions and the potential modeling schemes is given in Chapter 1. In Chapter 2, the developed population balance model forms a sound basis for further investigations of molecular weight/degree branching distribution. In Chapter 3, the model from Chapter 2 has been developed further to investigate the effect of multiradicals and gelation on the molecular weight distributions. In Chapter 4, we provide a model of the molecular weight distribution under circumstances of ldPE for a tubular reactor and for a series of continuous stirred tank reactors. A set of models to calculate the contraction factor of the radius of gyration, which to maximum extent accounts for the radical polymerization kinetics, is presented in Chapter 5. A full 2-dimensional model of ldPE chain length/branching distribution is provided in Chapter 6. The focus of Chapter 7 was especially on the role of combination termination in the context of 2- and 3-dimensional population balance models, implying that a mathematically non-linear problem had to be addressed in those modeling schemes

Tabu-KM: A Hybrid Clustering Algorithm Based on Tabu Search Approach

The clustering problem under the criterion of minimum sum of squares is a non-convex and non-linear program, which possesses many locally optimal values, resulting that its solution often falls into these trap and therefore cannot converge to global optima solution. In this paper, an efficient hybrid optimization algorithm is developed for solving this problem, called Tabu-KM. It gathers the optimization property of tabu search and the local search capability of k-means algorithm together. The contribution of proposed algorithm is to produce tabu space for escaping from the trap of local optima and finding better solutions effectively. The Tabu-KM algorithm is tested on several simulated and standard datasets and its performance is compared with k-means, simulated annealing, tabu search, genetic algorithm, and ant colony optimization algorithms. The experimental results on simulated and standard test problems denote the robustness and efficiency of the algorithm and confirm that the proposed method is a suitable choice for solving data clustering problems

Three-dimensional chain-length-branching-combination points distribution modeling of low density polyethylene in a continuous stirred tank reactor allowing for gelation

The focus of this paper is especially on the role of combination termination in the context of 3-dimensional population balance modeling of trivariate chain length/number of branch points/number of combination points distribution for low-density Polyethylene. Termination by combination is a well-known termination mechanism in radical polymerization and regarding low-density Polyethylene many authors have assumed this mechanism to be present. The ratio between disproportionation and combination termination in the previous studies varies, but usually the two mechanisms are thought of equal importance. Full 3-dimensional population balance equations are solved by a combination of the 2-dimensional Galerkin-finite element method and the pseudo distributions method to estimate chain length/branching/number of combination points distributions. Termination by combination is treated in a different scheme than the framework employed for other kinetic reactions. Good agreement with Monte Carlo results has been observed for low-density Polyethylene-like kinetics