Polymeric prodrugs containing neridronate and ferrocene: Synthesis,characterization, and antimalarial activity

Polyamidoamine prodrugs containing ferrocene derivatives and neridronate were successfully synthesized and characterized by NMR, FTIR, SEM, and EDX analyses. Appearance of characteristic peaks in ¹H and ³¹P NMR or EDX spectra were used to confirm the presence of neridronate or ferrocene in the conjugates and co-conjugates. In vitro evaluation of the new materials revealed improved antimalarial activity, especially for conjugate 5 and corresponding co-conjugate 8, when compared with chloroquine and quinine. Hemolysis studies revealed that synthesized prodrugs had no effect on the integrity of the host red blood cell membrane; a direct effect on the intra-erythrocytic parasite was, however, noted.     

Automatic correction of background phase offset in 4D-flow of great vessels and of the heart in MRI using a third-order surface model

Magnetic Resonance Materials in Physics, Biology and Medicine - To evaluate an automatic correction method for velocity offset errors in cardiac 4D-flow acquisitions. Velocity offset correction was...     

Tests of two types of bypass for downstream migration of eels at a small hydroelectric power plant

Efficiencies of two types of bypass, a surface and a bottom sluice, were tested for the natural downstream migration of silver eels Anguilla anguilla at a small hydroelectric power plant at Halsou, on the River Nive in France. Naturally migrating eels were caught after their passage through either bypass. A total of 637 eels were trapped during the three‐year study. Total efficiency for both bypasses, evaluated on the basis of downstream movement of radiotagged eels, ranged from 56% to 64%. Given a bias due to hydrological conditions at the time of the runs, the precise efficiency of each separate bypass was not calculated. However, preferred passage through the bottom bypass for both tagged and untagged eels was confirmed by telemetry, as three to four times as many eels transited through the bottom bypass compared to the surface one. The behaviour of 74 individuals released in the forebay was observed by radiotelemetry. Close to half of the radiotagged eels returned up the headrace after their release, and most eventually migrated downstream over the dam with appropriate environmental conditions. Upon arrival at the power plant, eels displayed foraging behaviour in the forebay with frequent displacement interrupted by long resting periods in zones with low current. The repulsive effect of the trashrack located in front of the turbine intake increased with increasing turbined discharge. The study indicated that a trashrack with a smaller bar‐spacing (around 20 mm), associated with an appropriate bypass, could deflect a large proportion of the female eels from the turbines. However, this solution needs to be tested on site to quantify the risk of mortality due to impingement on the trashrack. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis,receptor binding,molecular modeling,and proliferative assays of a series of 17alpha-arylestradiols

A series of new derivatives of estradiol substituted at position 17alpha by various aryls has been synthesized. This was made possible by efficient activation methods for the addition of aryllithiums to the carbonyl group at position 17 of estrone by using tetramethylethylenediamine (TMEDA) or BF3 x OEt2. Their relative binding affinity (RBA) for the alpha and the beta forms of the estrogen receptor (ER) have been measured. All except one of the compounds synthesized had an RBA value of around 10 % which indicates a level of tolerance towards the bulky substituent at position 17. The lipophilicity values measured for these compounds are higher than that found for estradiol (E2). A study of their proliferative/antiproliferative effects was carried out on hormone-dependent (MCF7) and hormone-independent (MDA-MB231) breast cancer cell lines. It is interesting to note that all the compounds are estrogenic. The possibility of easily attaching an iodine at the end of a phenyl spacer opens up a route to new radiopharmaceuticals for use in radioimaging.     

A new instrument for automated microcontact printing with stamp load adjustment

An instrument for automated microcontact printing (microCP) on microscope slides is described. The movement of the stamp, which is actuated by a computer controlled pneumatic actuator, is precisely guided until it makes contact with the substrate. As a consequence, the absolute position of the microprinted patterns is reproducible over a series of substrates with 1 mum standard deviation. Exchange of substrates and stamps is a quick and simple procedure. This makes possible the microprinting of adjacent or superimposable patterns, with different products, in a reproducible manner. Furthermore, a novel approach is described for adjusting the load on the stamp during contact. Two adjustable screws are set up so that their length (with reference to the substrate holder) limits the stamp compression during contact. The load on the stamp is proportional to the stamp compression and from the experimental point of view, this is controlled by the operator adjusting the screws. This makes possible the microCP with stamps incorporating large surface features as well as stamps with isolated features raised on the surface. For proof of concept, automated microCP of a single parallelepiped polydimethylsiloxane feature, with a surface of 2 cm x 30 microm and a height of 25 mum, is demonstrated inside a microfluidic channel without roof collapse. A second example is provided with a single cross feature, possessing an overall surface of 140 x 140 microm(2) and a height of 14 microm. Potential applications of this versatile, inexpensive and compact instrument are discussed. The machine's potential for high throughput also makes it suitable for mass production applications.     

Microstructured silicon membrane with soft suspension beams for a high performance MEMS microspeaker

This study presents a novel approach to MEMS microspeakers design aiming to tackle two main drawbacks of conventional microspeakers: their poor sound quality and their weak efficiency. For this purpose, an acoustic emissive surface based on a very light but very stiff structured silicon membrane was designed and microfabricated. This architecture, for which the membrane undesirable vibration modes were reduced to only three within the microspeaker bandwidth, is promising to let the microspeaker produce high sound quality from 300?Hz to 20?kHz. This silicon membrane is suspended by a whole set of silicon springs designed to enable out-of-plane displacements as large as 300?μm. Different geometries of springs were considered and the material maximum stress was analyzed in each case by finite element modeling. The proposed structure promises an efficiency of 10^?4, that is to say ten times higher than that of conventional microspeakers.     

Acute Cycling Exercise Induces Changes in Red Blood Cell Deformability and Membrane Lipid Remodeling

Here we describe the effects of a controlled, 30 min, high-intensity cycling test on blood rheology and the metabolic profiles of red blood cells (RBCs) and plasma from well-trained males. RBCs demonstrated decreased deformability and trended toward increased generation of microparticles after the test. Meanwhile, metabolomics and lipidomics highlighted oxidative stress and activation of membrane lipid remodeling mechanisms in order to cope with altered properties of circulation resulting from physical exertion during the cycling test. Of note, intermediates from coenzyme A (CoA) synthesis for conjugation to fatty acyl chains, in parallel with reversible conversion of carnitine and acylcarnitines, emerged as metabolites that significantly correlate with RBC deformability and the generation of microparticles during exercise. Taken together, we propose that RBC membrane remodeling and repair plays an active role in the physiologic response to exercise by altering RBC properties.     

Investigation of Slow-Propagation Tungsten Delay Mixtures

The burning characteristics and reliability of slow-propagation tungsten delay mixtures (characteristic time 38–42 s/in) were studied experimentally by using various mixture compositions and tungsten particle sizes. Thermal analysis showed that potassium perchlorate is vital to initiate the reaction. Gravimetric analysis indicated that during the reaction overall mass loss of the delay mixtures did not exceed 5% compared to their initial mass. A mixture containing a tungsten powder of 6–8 μm was found to have the lowest effective activation energy, facilitating good ignition and burning zone propagation. The results of this study were successfully used to design a tiny delay which exhibited reliable ignition, burning and propagation characteristics under extreme conditions.     

Capillary-based static self-assembly in higher organisms

Organized structures produced by dynamic self-assembly are often observed in animal groups. Static self-assembly, however, has to date only been observed at the cellular and sub-cellular levels. The aim of this study was to analyse organized structures in immobile whirligig beetle groups on the water surface. We used theoretical and computational approaches to model the meniscus around whirligig beetles and to calculate the surface energy for configurations involving two beetles. Theoretical predictions were then tested using live insects and resin casts. Observations were also made for three and more casts. The meniscus of whirligig beetles had a bipolar shape with two concave parts. For two beetles, predicted configurations based on energy minima corresponded to beetles in contact by their extremities, forming lines and arrows, and agreed well with observations. Experimental results for three and more beetle casts revealed new geometrical arrangements similar to those obtained with colloids at interfaces. This study provides the first example of static self-assembly at the inter-organism level and shows the importance of capillary interactions in such formations. We identify the ecological context in which our findings are of relevance.     

Crack tip enrichment in the XFEM using a cutoff function

We consider a variant of the eXtended Finite Element Method (XFEM) in which a cutoff function is used to localize the singular enrichment surface. The goal of this variant is to obtain numerically an optimal convergence rate while reducing the computational cost of the classical XFEM with a fixed enrichment area. We give a mathematical result of quasi‐optimal error estimate. One of the key points of this paper is to prove the optimality of the coupling between the singular and the discontinuous enrichments. Finally, we present some numerical computations validating the theoretical result. These computations are compared with those of the classical XFEM and a non‐enriched method. Copyright © 2008 John Wiley & Sons, Ltd.