Perfluorooctyl Bromide Polymeric Capsules as Dual Contrast Agents for Ultrasonography and Magnetic Resonance Imaging

Polymeric capsules with a thick shell made of biodegradable and biocompatible polymer and a liquid core of perfluorooctyl bromide (PFOB) were evaluated for stability as well as for ultrasound and magnetic resonance imaging (MRI) contrast enhancement. The method of preparation allows the mean capsule diameter to be regulated between 70 nm and 25 µm and the capsule thickness‐to‐radius ratio from 0.25 to 0.54. Capsule diameter remains stable at 37 °C in phosphate buffer for at least 4 and 6 h for nanocapsules and microcapsules, respectively. The in vitro ultrasound signal‐to‐noise ratio (SNR) was measured from 40 to 60 MHz for 6 µm and 150 nm capsules: the SNR increases with capsule concentration up to 20–25 mg mL⁻¹, and then reaches a plateau that depends on capsule diameter (13.5 ± 1.5 dB for 6 µm and 6 ± 2 dB for the 150 nm capsules). The ultrasound SNR is stable for up to 20 min for microcapsules and for several hours for nanocapsules. For nanocapsules, the thinner the shell, the larger the SNR and the more compressible the capsules. Nanocapsule suspensions imaged in vitro with a commercial ultrasound imaging system (normal and tissue harmonic imaging modes, 7–14 MHz probe) were detected down to concentrations of 12.5 mg mL⁻¹. Injections of nanocapsules (200 µg ml⁻¹) in mice in vivo reveal that the initial bolus passage presents significant ultrasound enhancement of the blood pool during hepatic imaging (7–14 MHz probe, tissue harmonic imaging mode). ¹⁹F‐MRI images were obtained in vitro at 9.4T using spin‐echo and gradient echo sequences and allow detecting nanocapsules in suspension (50 mg mL⁻¹). In conclusion, these results show initial feasibility for development of these capsules toward a dual‐modality contrast agent.     

Fast NMR Methods for Measuring in the Direct and/or Competition Mode the Dissociation Constants of Chemical Fragments Interacting with a Receptor

Ligand-based NMR screening represents a powerful method in fragment-based drug discovery for the identification of chemical matter interacting with the receptor of interest. The large dynamic range of these methods allows the detection of weakly binding ligands. However, the methodology has not been extensively used for quantifying the strength of these interactions. This knowledge is important for ranking fragments according to their binding strength and for prioritizing structure-based and medicinal chemistry activities. Rapid NMR methods for measuring the dissociation constant in direct and competition modes are presented here. The theory underpinning these methods are presented, along with their application to the measurement of the binding affinities of several ligands of the heat shock protein 90.     

Recent progress and prospective of medium and high temperatures thermal energy storage materials

开发中高温储热材料及其制备方法是储热技术发展的关键之一.本文结合中高温储热材料的分类,特点,应用及存在的问题对中高温储热材料的研究进展进行了综述,主要包括显热储热材料,热化学储热材料以及潜热储热材料.探讨了复合结构储热材料及其制备工艺,进一步介绍了其最新研究进展,并对中高温储热材料的下一步研究进行了展望,提出开发高性能纳微复合结构储热材料是未来研究的重点.     

Direct Laser Patterning of Soft Matter: Photothermal Processing of Supported Phospholipid Multilayers with Nanoscale Precision

Direct laser patterning of supported phospholipid multilayers is investigated. Spin coating is used to fabricate stacked bilayers of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphate (DOPA). Photothermal processing with a focused laser beam at λ = 514 nm allows removal of the coating at predefined positions without causing any significant change in adjacent areas. Moreover, processing with nanoscale precision is feasible despite the soft and fluid nature of phospholipid films. In particular, holes with diameters from 1.8 µm down to 300 nm and below are fabricated by using a 1/e² laser spot size of about 2.5 µm. In addition, patterning is also very flexible and can be carried out over macroscopic length scales and at short processing times. Considering these features photothermal laser processing constitutes a powerful tool for micro‐ and nanopatterning of phospholipid films.     

Durability of GFRP Reinforcing Bars Embedded in Moist Concrete

This paper presents mechanical, microstructural, and physical characterization of glass fiber-reinforced polymer (GFRP) bars exposed to concrete environment. GFRP bars were embedded in concrete and exposed to tap water at 23, 40, and 50°C to accelerate the effect of the concrete environment. The measured tensile strengths of the bars before and after exposure were considered as a measure of the durability performance of the specimens and were used for long-term properties prediction based on the Arrhenius theory. In addition, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy were used to characterize the aging effect on the GFRP reinforcing bars. The results showed that the durability of mortar-wrapped GFRP bars and exposed to tap water was less affected by accelerated aging than the bars exposed to simulated pore-water solution. These results confirmed that the concerns about the durability of GFRP bars in concrete, based on simulated laboratory studies in alkaline solutions, do not properly correspond to the actual service life in concrete environments.     

Efficiency improvement for geothermal power generation to meet summer peak demand

Geothermal power is an important part of New Zealand's renewable electricity supply due to its attractive cost and reliability. Modular type binary cycle plants have been imported and installed in various geothermal fields in New Zealand, with plans for further expansion. Power output of these plants deteriorates in the summer because plant efficiency depends directly on the geothermal resource and the ambient temperature. As these plants normally use air-cooled condensers, incorporating a water-augmented air-cooled system could improve the power output in summer thereby matching the peak air-conditioning demand. In this work, power generation for the Rotokawa plant was characterized using a similar plant performance and local weather. The improved performance was modelled for retrofit with a wet-cooling system. Maximum generation increase on the hottest day could be 6.8%. The average gain in power over the summer, November–February, was 1.5%, and the average gain for the whole year was 1%. With current binary unit generation capacity at the Rotokawa plant of 35 MW, investment in a water-augmented air-cooled system could provide 2 MW of peak generation on the hottest days. This investment in efficiency is found to compare favourably to other supply options such as solar PV, wind or gas.     

Correction to Mathieu and Rapp (2009).

Reports an error in "Laying the foundation for successful team performance trajectories: The roles of team charters and performance strategies" by John E. Mathieu and Tammy L. Rapp (Journal of Applied Psychology, 2009[Jan], Vol 94[1], 90-103). In the article “Laying the Foundation for Successful Team Performance Trajectories: The Roles of Team Charters and Performance Strategies,” by John E. Mathieu and Tammy L. Rapp (Journal of Applied Psychology, 94, 90–103), the “High Chart–Low Strategy” and the “Low Chart–High Strategy” lines were inadvertently reversed in Figure 1. Below is the corrected version of Figure 1. (The following abstract of the original article appeared in record 2009-00697-021.) This study examined the influences of team charters and performance strategies on the performance trajectories of 32 teams of master's of business administration students competing in a business strategy simulation over time. The authors extended existing theory on team development by demonstrating that devoting time to laying a foundation for both teamwork (i.e., team charters) and taskwork (performance strategies) can pay dividends in terms of more effective team performance over time. Using random coefficients growth modeling techniques, they found that teams with high-quality performance strategies outperformed teams with poorer quality strategies. However, a significant interaction between quality of the charters of teams and their performance strategies was found, such that the highest sustained performances were exhibited by teams that were high on both features. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two‐Phase Hydroformylation of Higher Olefins Using Randomly Methylated α‐Cyclodextrin as Mass Transfer Promoter: A Smart Solution for Preserving the Intrinsic Properties of the Rhodium/Trisulfonated Triphenylphosphine Catalytic System

The two‐phase hydroformylation of higher olefins with the rhodium/trisulfonated triphenylphosphine catalytic system in the presence of various chemically modified α‐cyclodextrins has been investigated. These cyclodextrins allowed us to increase greatly the reaction rate and the chemoselectivity of the reaction but, contrary to what has been observed previously with the chemically modified β‐cyclodextrins, the linear to branched aldehydes ratio was not affected by the presence of α‐cyclodextrin derivatives. Indeed, the latter was found to be similar to that obtained without any mass transfer promoter, suggesting that the catalytic species are stable in the presence of α‐cyclodextrin derivatives.     

Généralisation de la méthode de l’ouverture pour l’étude du rayonnement paraxial des nouveaux concepts de réflecteurs

The computation and development of new types of antennas with reflectors have required the elaboration of a specific analytical method. The authors develop a software for processing reflectors of any profile, determined analytically or over a set of points, with surfaces of finite or perfect, isotropic or anisotropic reflectivity. In a first step, the choice of the equivalent aperture method combined with the fast Fourier transform is justified. An original implementation scheme of the method is then made conform to the above requirements and to the whole set of new concepts developped nowadays. The results obtained prove the precision of the new method and its suitability for radiation field simulation of antennas which are under construction for communication by satellites.