Les phases SrLa2Al2O7 et SrGd2Al2O7

SrLa₂Al₂O₇ and SrGd₂Al₂O₇ belong to the structural type Sr₃Ti₂O₇. In SrGd₂Al₂O₇ strontium and gadolinium occupy respectively the 12 and 9 coordinated sites, whereas in SrLa₂Al₂O₇ the homologous cations are statistically distributed. The fluorescence spectra of both phases activated by Eu³⁺ ions show that the only possible position of Eu³⁺ is the 9 coordinated site.     

Real‐time hybrid control of electrohydraulic active suspension

Electrohydraulic actuators are an attractive choice for active suspension, because these systems provide a high power‐to‐weight ratio. However, their dynamics are highly nonlinear. In addition, the use of one simple controller for both position and force is complicated, because there is a compromise between them in the case of active suspension. Most existing controllers do not efficiently fulfill the requirements, because only one state variable is considered. In this paper, we address these problems by developing a new hybrid controller for both position and force and implementing it in a real‐time test bench. Our goal is to control the vertical position of the passenger seat while tracking the force transmitted to passengers and keeping it within tolerable and comfortable limits. Therefore, the proposed controller is a combination of two controllers. Its flexible structure redirects the control signal to control the proper controlled state variable. The real‐time results of the newly designed hybrid controller are compared with those obtained using a classical proportional integral derivative controller, because this is the most widely used controller in the industry. As expected, the proposed controller demonstrates better performance in real‐time operation. Copyright © 2017 John Wiley & Sons, Ltd.     

Cardiac Disease Alters Myocardial Tissue Levels of Epoxyeicosatrienoic Acids and Key Proteins Involved in Their Biosynthesis and Degradation

CYP2J2 is the main epoxygenase in the heart that is responsible for oxidizing arachidonic acid to cis-epoxyeicosatrienoic acids (EETs). Once formed, EETs can then be hydrolyzed by soluble epoxide hydrolase (sEH, encoded by EPHX2) or re-esterified back to the membrane. EETs have several cardioprotective properties and higher levels are usually associated with better cardiac outcomes/prognosis. This study investigates how cardiovascular disease (CVD) can influence total EET levels by altering protein expression and activity of enzymes involved in their biosynthesis and degradation. Diseased ventricular cardiac tissues were collected from patients receiving Left Ventricular Assist Device (LVAD) or heart transplants and compared to ventricular tissue from controls free of CVD. EETs, and enzymes involved in EETs biosynthesis and degradation, were measured using mass spectrometric assays. Terfenadine hydroxylation was used to probe CYP2J2 activity. Significantly higher cis- and trans-EET levels were observed in control cardiac tissue (n = 17) relative to diseased tissue (n = 24). Control cardiac tissue had higher CYP2J2 protein levels, which resulted in higher rate of terfenadine hydroxylation, compared to diseased cardiac tissues. In addition, levels of both NADPH-Cytochrome P450 oxidoreductase (POR) and sEH proteins were significantly higher in control versus diseased cardiac tissue. Overall, alterations in protein and activity of enzymes involved in the biosynthesis and degradation of EETs provide a mechanistic understanding for decreased EET levels in diseased tissues.     

An Original and Efficient Antibiotic Adjuvant Strategy to Enhance the Activity of Macrolide Antibiotics against Gram-Negative Resistant Strains

Gram-negative bacteria were reported as a significant cause of infections in both community and nosocomial settings. Considered as one of the greatest threats to public health, the spread of bacteria drug resistance and the lack of effective alternative treatment options remains problematic. Herein, we report a promising strategy to combat Gram-negative resistant strains consisting of the combination of a macrolide antibiotic with a polyaminoisoprenyl adjuvant derivative leading to a significant decrease of antibiotic resistance.     

Local Electronic Structure of Molecular Heterojunctions in a Single‐Layer 2D Covalent Organic Framework

The synthesis of a single‐layer covalent organic framework (COF) with spatially modulated internal potentials provides new opportunities for manipulating the electronic structure of molecularly defined materials. Here, the fabrication and electronic characterization of COF‐420: a single‐layer porphyrin‐based square‐lattice COF containing a periodic array of oriented, type II electronic heterojunctions is reported. In contrast to previous donor–acceptor COFs, COF‐420 is constructed from building blocks that yield identical cores upon reticulation, but that are bridged by electrically asymmetric linkers supporting oriented electronic dipoles. Scanning tunneling spectroscopy reveals staggered gap (type II) band alignment between adjacent molecular cores in COF‐420, in agreement with first‐principles calculations. Hirshfeld charge analysis indicates that dipole fields from oriented imine linkages within COF‐420 are the main cause of the staggered electronic structure in this square grid of atomically–precise heterojunctions.     

Spermine Derivatives of Indole-3-carboxylic Acid,Indole-3-acetic Acid and Indole-3-acrylic Acid as Gram-Negative Antibiotic Adjuvants

The discovery of new antibiotic adjuvants is an attractive option for overcoming antimicrobial resistance. We have previously reported the discovery of a bis-6-bromoindolglyoxylamide derivative of spermine as being able to enhance the action of antibiotics against Gram-negative bacteria but suffers from being cytotoxic and red-blood cell haemolytic. A series of analogues was prepared exploring variation of the indolglyoxylamide unit, to include indole-3-acrylic, indole-3-acetic and indole-3-carboxylate units, and evaluated for antibiotic enhancing properties against a range of Gram-negative bacteria, and for intrinsic antimicrobial, cytotoxic and haemolytic properties. Two spermine derivatives, bearing 5-bromo-indole-3-acetic acid ( 17 ) and 5-methoxy-indole-3-acrylic acid ( 14 ) end groups were found to exhibit good to moderate antibiotic adjuvant activities for doxycycline towards the Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae, but with more modest intrinsic antimicrobial activity and greatly reduced cytotoxic and haemolytic properties. The mechanism of action of the latter derivative identified its ability to disrupt the outer membranes of bacteria and to inhibit the AcrAB-TolC efflux pump directly or by inhibiting the proton gradient.     

Benzofuroxan Derivatives as Potent Agents against Multidrug-Resistant Mycobacterium tuberculosis

Tuberculosis (TB) is currently the leading cause of death related to infectious diseases worldwide, as reported by the World Health Organization. Moreover, the increasing number of multidrug-resistant tuberculosis (MDR-TB) cases has alarmed health agencies, warranting extensive efforts to discover novel drugs that are effective and also safe. In this study, 23 new compounds were synthesized and evaluated in vitro against the drug-resistant strains of M. tuberculosis. The compound 6-((3-fluoro-4-thiomorpholinophenyl)carbamoyl)benzo[c][1,2,5]oxadiazole 1-N-oxide ( 5 b ) was particularly remarkable in this regard as it demonstrated MIC₉₀ values below 0.28 μM against all the MDR strains evaluated, thus suggesting that this compound might have a different mechanism of action. Benzofuroxans are an attractive new class of anti-TB agents, exemplified by compound 5 b , with excellent potency against the replicating and drug-resistant strains of M. tuberculosis.