Structure and properties of solid-state synthesized poly(3′,4′-ethylenedioxy-2,2′:5′,2″-terthiophene)

A polyterthiophene derivative: poly(3′,4′-ethylenedioxy-2,2′:5′,2″-terthiophene) was synthesized by solid-state oxidative-polymerization of 3′,4′-ethylenedioxy-2,2′:5′,2″-terthiophene (TET) in various ratios of oxidant (FeCl₃) to the monomer (TET). The resulting polymers were characterized by FT-IR, ¹H NMR, TEM, SEM, UV–vis–NIR, GPC, X-ray diffraction, EDX, CV, galvanostatic charge–discharge, as well as TGA and conductivity measurements. The results showed that the as-made poly(TET)s were partially in doped state with a conductivity ranging from 2.1 × 10^?3 S cm^?1 to 8.1 × 10^?3 S cm^?1 at room temperature, and exhibited good thermal stability in nitrogen up to 337–356 °C. The poly(TET)s showed a similar UV–vis absorption peak at 462 nm in acetonitrile. In addition, as-made poly(TET)s had low molecular weight ranging from 3300 to 3500 with microstructured morphology including nanorodes and nanofibers, and presented one redox couple at 1.1–1.2 V(ox) and 0.6–0.7 V(re) in 0.1 M Et₄NBF₄ acetonitrile solution. A moderate specific capacitance of 71 F g^?1 for poly(TET) modified graft electrode was obtained within the potential range of ?0.2 V to 0.5 V in 1 M H₂SO₄ solution. X-ray diffraction results imply the enhanced crystallinity of poly(TET)s, indicating the existence of crystalline phase in polymer matrix. Furthermore, the comparison of results from every measurement indicated that the [FeCl₃]/[TET] ratio strongly affects the morphology of the poly(TET), and the fibrillar growth tendency of poly(TET) was observed with the increase of the [FeCl₃]/[TET] ratio, and long-length fibrillar morphology occurred in the highest [FeCl₃]/[TET] ratio.     

Numerical modelling of masonry joints degradation in built tunnels

Old tunnels are generally supported by masonry structure. Nowadays, these constructions present many instability problems (cracks, collapses, convergence, etc.) due to aging phenomena on both blocks and mortars. After the analysis of blocks mechanical behaviour over time [Idris, J., Verdel, T., Al-Heib, M., 2008a. Numerical modelling and mechanical behaviour analysis of ancient tunnel masonry structures. Tunnelling and Underground Space Technology 23, 251–263.], we try in this paper to simulate the evolution of masonry joints mechanical behaviour in built tunnels and to quantify the influence of their mechanical proprieties on the tunnel behaviour by the help of the experimental design method and distinct elements numerical modelling.     

Agent-based communities of web services: an argumentation-driven approach

The objective of this paper is to discuss how to sustain the growth of Web services through the use of communities. A community aims at gathering Web services with the same functionality independently of their origins, locations, and functioning. To make Web services more responsive to the environment in which they run and to be more flexible when managing communities, Web services are associated with software agents enhanced with argumentation capacities. This type of agents persuade and negotiate with other peers for the sake of letting their respective Web services reach their goals in an efficient way. Associating Web services with this type of agents allows them to select good communities and allow the communities to host the good Web services and to select the best ones for composite scenarios. Furthermore, this provides satisfactory solutions for three open problems: starvation (Web services refuse all the possibilities of joining communities), competition-free (Web services accept joining any community without being selective), and unfairness (always the same Web services members of a community are selected out of many others to participate in composite scenarios). In addition, the paper presents a formal and computational persuasive and negotiation protocol to manage the attraction and retainment of Web services in the communities and their identification for composite services.     

Flavonoids Targeting Cancer Stem Cells for Augmenting Cancer Therapeutics

Cancer stem cells (CSC) have been identified in several types of solid tumors. In some cases, CSC may be the source of all the tumor cells, the cause of the tumor’s resistance to chemotherapeutic agents, and the source of metastatic cells. Thus, a combination therapy targeting non-CSC tumor cells as well as specifically targeting CSCs holds the potential to be highly effective. Natural products (NPs) have been a historically rich source of biologically active compounds and are known for their ability to influence multiple signaling pathways simultaneously with negligible side effects. In this review, we discuss the potential of NPs in targeting multiple signaling pathways in CSC and their potential to augment the efficacy of standard cancer therapy. Specifically, we focus on the anti-CSC activities of flavonoids, FDA-approved drugs originating from natural sources. Additionally, we emphasize the potential of NPs in targeting microRNA-mediated signaling, given the roles of microRNA in the maintenance of the CSC phenotype.     

Genes and Longevity of Lifespan

Aging is a complex process indicated by low energy levels, declined physiological activity, stress induced loss of homeostasis leading to the risk of diseases and mortality. Recent developments in medical sciences and an increased availability of nutritional requirements has significantly increased the average human lifespan worldwide. Several environmental and physiological factors contribute to the aging process. However, about 40% human life expectancy is inherited among generations, many lifespan associated genes, genetic mechanisms and pathways have been demonstrated during last decades. In the present review, we have evaluated many human genes and their non-human orthologs established for their role in the regulation of lifespan. The study has included more than fifty genes reported in the literature for their contributions to the longevity of life. Intact genomic DNA is essential for the life activities at the level of cell, tissue, and organ. Nucleic acids are vulnerable to oxidative stress, chemotherapies, and exposure to radiations. Efficient DNA repair mechanisms are essential for the maintenance of genomic integrity, damaged DNA is not replicated and transferred to next generations rather the presence of deleterious DNA initiates signaling cascades leading to the cell cycle arrest or apoptosis. DNA modifications, DNA methylation, histone methylation, histone acetylation and DNA damage can eventually lead towards apoptosis. The importance of calorie restriction therapy in the extension of lifespan has also been discussed. The role of pathways involved in the regulation of lifespan such as DAF-16/FOXO (forkhead box protein O1), TOR and JNK pathways has also been particularized. The study provides an updated account of genetic factors associated with the extended lifespan and their interactive contributory role with cellular pathways.     

Experimental methods in chemical engineering: Thermogravimetric analysis—TGA

Thermogravimetric analysis (TGA) is a quantitative analytical technique that monitors the mass of a sample from 1 mg to several g as a furnace ramps temperature to as high as 1600°C under a stable or changing gas flow. The first gravimetric test was in 27 BC when Vitruvius measured limestone's change of mass as it calcined to lime. In modern chemical engineering, researchers apply the technique to derive conversions, kinetics, and mechanisms for any process with a change of mass by isothermal, non-isothermal, and quasi-isothermal methods. The mass drops as the sample decomposes, volatile compounds evaporate, or the oxidation state decreases, while in reactive environments (with O₂, for example), the mass of transition metals may increase. TGA is incapable of detecting phase transitions, polymorphic transformations, or reactions for which mass is invariant. DSC or DTA couple with TGA to help deconvolute a DSC plot by separating physical changes from chemical changes. Evolved gas analysis techniques monitor the gaseous products exiting the TGA furnace on-line as the temperature ramps. A bibliometric map of keywords from articles citing TGA indexed by Web of Science in 2016 and 2017 identified five research clusters: nanoparticles, performance, and films; crystal structures, acid, and oxidation; composites, nanocomposites, and mechanical properties; kinetics, pyrolysis, and temperature; and adsorption, water and wastewater, and aqueous solutions. This review provides an overview of the basic principles of modern TGA.     

Lightweight concrete in hot coastal areas

An experimental study was carried out to examine different mixtures made with selected lightweight aggregates for the purpose of producing lightweight concrete. A relatively suitable product is sought in order to provide good quality building materials that can satisfy the conditions of hot coastal environments. Three ways of producing lightweight concrete were used, i.e., lightweight crushed bricks, lightweight expanded clay aggregate (LECA), and no-fines concrete. Physical and mechanical properties of the mixtures were examined to ascertain the suitability and applicability of the three concretes. The results of this pilot study suggest that there are possibilities of producing structural lightweight concrete using crushed bricks with the condition of further refinements in the mixture design.     

Low frequency noise in complementary npn and pnp polysilicon emitter bipolar junction transistors

Low frequency noise characteristics of high voltage, high performance complementary polysilicon emitter bipolar transistors are described. The influence of the base biasing resistance, emitter geometry and temperature on the noise spectra are discussed. The npn transistors studied exhibited 1/f and shot noise, but the pnp transistors are characterized by significant generation–recombination noise contributions to the total noise. For both types of transistors, the measured output noise is determined primarily by the noise sources in the polysilicon–monosilicon interface. The level of the 1/f noise is proportional to the square of the base current for both npn and pnp transistors. The contribution of the 1/f noise in the collector current is also estimated. The area dependence of 1/f noise in both types of transistors as well as other npn bipolar transistors are presented.     

A novel induction heating fluidized bed reactor: Its design and applications in high temperature screening tests with solid feedstocks and prediction of defluidization state

A novel mini induction heating fluidized bed reactor (IHFBR) is introduced which was developed to carry out screening tests of high temperature reactions up to 1500°C particularly for solid feedstocks. Despite conventional mini reactors, this reactor mimics real scenario of solid feeding in industrial reactors: cold feedstock is injected within 1 s from a lift tube, then particles reach reaction temperature in less than 5 s in a reaction zone. The lift tube (9.5 cm diameter) is also the gas distributor of the fluidized bed (2.5 cm diameter) so that the bed is completely fluidized with uniform gas distribution. Beside facilities to perform tests in a fluidized bed, another important feature of this reactor is prediction of the defluidization state in the bed. Not only reproducible data are generated, but also many tests can be conveniently carried out, that is, one test per hour. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1507–1523, 2015     

Thermal properties of calcium carbonate powder reinforced vinyl ester composites: Pilot study

The viscoelastic properties of vinyl ester (VE) composites filled with calcium carbonate (CC) (CaCO₃) powder have been evaluated using the dynamic mechanical analysis (DMA) technique. It was found that irrespective of the percentage by weight of CaCO₃ powder, the VE composites postcured in an oven up to 60°C have higher glass transition temperatures (T_g) and storage modulus than their counterparts cured at ambient conditions. However, the loss moduli were lower for composites postcured in an oven than their ambient cured counterparts. It was also found that the crosslinking density of the composites slightly increased with particulate (CaCO₃) loading and composites postcured in an oven have higher crosslinking density than their counterparts cured at ambient conditions. These results confirmed an increase in stiffness for composites with postcuring treatment. Micrographs by SEM were obtained and confirmed a close inter phase adhesion of the CC filler with the VE resin matrix in the composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013