Novel proton-exchange membrane based on single-step preparation of functionalized ceramic powder containing surface-anchored sulfonic acid

A novel approach to the synthesis of a low-cost proton-exchange membrane (PEM) based on the single-step preparation of a functionalized ceramic powder containing surface-anchored sulfonic acid (SASA) and a polymer binder, is presented for the first time. The added value of this technique, compared with earlier work published by our group, is the adoption of a direct, single-step synthesis, as opposed to a multiple-step synthesis. The latter requires an oxidation step, in order to convert the thiol group into a sulfonic group. SASA powders of different compositions have been prepared and characterized by means of Brunaur–Emmet–Teller (BET), thermogravimetric analysis–differential thermal analysis (TGA–DTG), differential scanning calorimeter (DSC), Fourier transformation infrared (FT-IR), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrochemical techniques. The lowest equivalent weight measured for SASA powders is 1281 g equiv.⁻¹. The ionic conductivity of a 100-μm-thick membrane is measured ex situ at room temperature (25 ± 3 °C) and the highest proton conductivity is 48 mS cm⁻¹. The typical pore size, for the SASA powders is less than 10 nm and ranges from 2 to 50 nm for the SASA-based membranes. The membranes are thermally stable up to 250 °C.     

Complex Effects of Sertraline and Citalopram on In Vitro Murine Breast Cancer Proliferation and on In Vivo Progression and Anxiety Level

Some selective serotonin reuptake inhibitors (SSRIs), primarily sertraline, demonstrate anti-proliferative activity in malignant cell-lines and in xenografted mouse models of colorectal tumor. There is, however, a paucity of comparative studies on the anti-tumor effects of SSRIs. We compared the in vitro and in vivo effects of sertraline and citalopram on murine 4T1 breast cancer. Grafted mice were used to determine the rate of tumor growth and survival as well as the impact of stress and antidepressant treatment on tumor progression and mortality and on pro-inflammatory cytokines. Sertraline, in the micromolar range, but not citalopram, induced a significant in vitro concentration-dependent inhibition of murine 4T1 cell proliferation and splenocyte viability. In contrast, sertraline (10 mg/kg/d), enhanced in vivo tumor growth. Contrary to the study’s hypothesis, chronic mild stress did not modify tumor growth in grafted mice. The in vitro effects of sertraline on tumor growth seem to be the opposite of its in vivo effects. The impact of sertraline treatment on humans with breast cancer should be further investigated.     

An Engineered Nanocomplex with Photodynamic and Photothermal Synergistic Properties for Cancer Treatment

Photodynamic therapy (PDT) and photothermal therapy (PTT) are promising therapeutic methods for cancer treatment; however, as single modality therapies, either PDT or PTT is still limited in its success rate. A dual application of both PDT and PTT, in a combined protocol, has gained immense interest. In this study, gold nanoparticles (AuNPs) were conjugated with a PDT agent, meso-tetrahydroxyphenylchlorin (mTHPC) photosensitizer, designed as nanotherapeutic agents that can activate a dual photodynamic/photothermal therapy in SH-SY5Y human neuroblastoma cells. The AuNP-mTHPC complex is biocompatible, soluble, and photostable. PDT efficiency is high because of immediate reactive oxygen species (ROS) production upon mTHPC activation by the 650-nm laser, which decreased mitochondrial membrane potential (^∆ψ_m). Likewise, the AuNP-mTHPC complex is used as a photoabsorbing (PTA) agent for PTT, due to efficient plasmon absorption and excellent photothermal conversion characteristics of AuNPs under laser irradiation at 532 nm. Under the laser irradiation of a PDT/PTT combination, a twofold phototoxicity outcome follows, compared to PDT-only or PTT-only treatment. This indicates that PDT and PTT have synergistic effects together as a combined therapeutic method. Our study aimed at applying the AuNP-mTHPC approach as a potential treatment of cancer in the biomedical field.     

PCP Characterizations of NP: Toward a Polynomially-Small Error-Probability

This paper strengthens the low-error PCP characterization of NP, coming closer to the upper limit of the BGLR conjecture. Consider the task of verifying a written proof for the membership of a given input in an NP language. In this paper, this is achieved by making a constant number of accesses to the proof, obtaining error probability that is exponentially small in the total number of bits that are read.     

Priority scheduling of distributed systems based on model checking

Priorities are used to control the execution of systems to meet given requirements for optimal use of resources, e.g., by using scheduling policies. For distributed systems it is hard to find efficient implementations for priorities; because they express constraints on global states, their implementation may incur considerable overhead. Our method is based on performing model checking for knowledge properties. It allows identifying where the local information of a process is sufficient to schedule the execution of a high priority transition. As a result of the model checking, the program is transformed to react upon the knowledge it has at each point. The transformed version has no priorities, and uses the gathered information and its knowledge to limit the enabledness of transitions so that it matches or approximates the original specification of priorities.     

Parameters related to fiber length and processing in cementitious composites

Effects of fiber length on the tensile and flexural performance of cast and extruded PVA fiber reinforced cement composites were investigated. Microstructural characterization, image analysis, and statistical tools were used to study the influence of processing and fiber length on fiber-matrix bond, fiber dispersion and fiber orientation in the composites. In the extruded composites, shorter fibers improved the performance. In the cast composites, longer fibers gave the best performance. This contradictory trend was found to be a result of differences in fiber failure mechanism, fiber distribution and fiber orientation. Microstructural observations indicated a strong matrix-fiber bond for the extruded composites. Statistical quantification of image analysis indicated a better distribution and alignment of shorter fibers in extruded composites.

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Résumé Les effets de la longueur des fibres sur les performances de tension et de flexion des composites moulés et des composites extrudés, à base de ciment renforcé et de fibres d’acétate de polyvinyle, ont été étudiés. La caractérisation microstructurale, l’analyse d’images et des outils statistiques ont été utilisés pour étudier l’influence du traitement et de la longueur des fibres sur le lien fibres-matrices, la dispersion et l’orientation des fibres dans les composites. Dans les composites extrudés, des fibres plus courtes ont amélioré les performances. Dans les composites moulés, des fibres plus longues ont engendré de meilleures performances. Cette tendance contradictoire s’est avérée être le résultat de différences dans le mécanisme de rupture des fibres, la distribution des fibres et l’orientation des fibres. Les observations microstructurales ont indiqué un lien matrice-fibres important pour les composites expulsés. La quantification statistique de l’analyse d’images a montré une meilleure répartition et un meilleur alignement des fibres plus courtes dans les composites extrudés.

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Editorial Note Prof. Dr. Surendra P. Shah is RILEM Senior Member. He participates in RILEM TCs 162-TDF (Test and design methods for steel fibre reinfored concrete) and EAS (Early age shrinkage induced stresses and cracking in cementitious systems). Prof. Shah is a member of the Management Advisory Committee of RILEM. He is also Editor in chief of Concrete Science and Engineering, a scientific journal published quarterly by RILEM Publications S.A.R.L.     

Why and how can human-related measures support software development processes?

In this paper we discuss why and how measures related to human aspects should be incorporated into software development processes. This perspective is based on the vast evidence that human aspects are the source of the majority of problems associated with software development projects. Having said that, we do not blame the humans involved in software development processes; rather, we suggest that human-related measures might be one means by which human aspects of software development processes can be supported.     

Direct ethylene glycol fuel-cell stack—Study of oxidation intermediate products

In the present paper, a ten 10 cm² direct ethylene glycol fuel-cell (DEGFC) stack based on a nanoporous proton-conducting membrane (NP-PCM) is used to study the electro-oxidation of ethylene glycol (EG) in acid medium under initial and steady-state conditions, and under the operating conditions of electrochemical titration. Ethylene glycol (EG) has a theoretical capacity 17% higher than that of methanol in terms of Ah ml⁻¹ (4.8 and 4, respectively); this is especially important for portable electronic applications. EG (bp 198 °C) is also a safer fuel for direct-oxidation fuel-cell (DOFC) applications than is methanol. A maximal power of 12 W (at 0.3 V cell⁻¹) at 80 °C has been achieved for a DEGFC fresh stack fed with 0.5 M EG/1.7 M triflic acid solution at ambient dry air pressure. The formation of oxidation by-products – glycolic and oxalic acids (most likely in parallel reactions) – has been proven by ion-chromatography analysis. On continuous feed of EG in order to maintain a concentration of about 0.5 M, the concentration of intermediates reached a maximum after about two fuel (EG) turnovers. After discharging without feeding the stack with EG, there was no further accumulation of these acids and their concentration decreased to almost zero. This is clear evidence that EG is a real fuel that can be converted completely to CO₂.     

Hydrated cement paste constituents observed with Atomic Force and Lateral Force Microscopy

Engineers have frequently used microscopy to better understand the structure of materials. Optical microscopy and scanning electron microscopy have been used for several decades to better understand the microstructure of cementitious composites. Very limited work has been performed to date in the cement area to study the structural characteristics of cementitious materials by Atomic Force Microscopy (AFM). This technical note describes observations from a series of images acquired using AFM as well as Lateral Force Microscopy (LFM). The objective of this work is to better understand how AFM and LFM techniques can be used as tools to better understand the nano and microstructure of cementitious materials. In this work the AFM and LFM techniques could distinguish between CSH particles and crystals of CH on the microscale. The LFM appears to be more sensitive to topographic changes and could more clearly distinguish between the different phases.