Intrinsic hydroquinone-functionalized aggregation-induced emission core shows redox and pH sensitivity

Aggregation-induced emission (AIE) fluorophores exhibit strong fluorescence in an aggregated state but emit no or weak fluorescence in dilute solutions. This emerging class of AIE optical materials comprise a variety of functionalities. Here an AIE luminescence core, 1-hydroquinol-1,2,2-triphenylethene (HQTPE), has been designed and synthesized. This AIE core is simple but is fundamentally important to chemistry because of its intrinsic redox and pH activities. The incorporation of hydroquinone (HQ) moiety into a common AIE core tetraphenylethene (TPE) yields HQTPE with unique fluorescent properties like nonlinear self-quenching over most other AIE-active fluorophores (AIEgens) so far reported. There are differences of photochemical properties between HQTPE, 1-benzoquinol-1,2,2-triphenylethene (QTPE, the oxidized counterpart) and its anions. Interestingly, as the solution concentration is increased, AIEgen HQTPE shows stronger fluorescence but QTPE exhibits rapid quenching of fluorescence in a nonlinear fashion, which are in agreement with theoretical studies. The fluorescence of HQTPE is also highly dependent on the pH value of media. We have further explored HQTPE as an ultrasensitive redox probe and efficient deoxidizer, which could lead to potential applications in health care, food security, environmental monitoring, optic and electronic devices.

Turbines and Structures for Ultra-High Pressure Ratio Aero-Engines

This paper describes the research carried out in the European Commission co-funded project LEMCOTEC (Low Emission Core Engine Technology) on aerodynamics for turbines and structures for compressors, combustors and turbines. The aim is to significantly contribute to the reduction of the environmental footprint of aviation with regard to emissions from aero engines. The LEMCOTEC turbine and structure technologies are directed primarily to act as enablers for higher thermal efficiency arising from increased overall pressure ratio. Thus the work is supporting increased operating temperatures, reduced core deformation, reduced cooling flows and increased performance to weight ratio, in addition to direct reduction of flow losses and associated component efficiency increases. The article details the targets for performance improvements, the validation of the technologies and how they, together with LEMCOTEC’s improved technologies on compressors and combustors, relate to the goal of building ultra-high pressure ratio engines.

[Fe iii] lines in the planetary nebula NGC 2392

The Eskimo Nebula (NGC 2392) is a young double-shell planetary nebula (PN). Its intrinsic structure and the responsible shaping mechanism are still not fully understood. We present new optical spectroscopy of NGC 2392 at two different locations to obtain the spectra of the inner and outer shells. Several [Fe iii] lines are clearly detected. We find that these [Fe iii] lines mostly originate from the inner shell. Therefore, we suggest that NGC 2392 might have an intrinsic structure similar to the Ant Nebula Mz 3, which exhibits a number of [Fe iii] lines from the central dense regions. In this scenario, the inner and outer shells correspond to the central emission core and the outer lobes of Mz 3, respectively.

X-ray standing wave measurements of adsorbates on metal surfaces

One of the main goals in surface science is the determination of the geometric structure of the surface, including the local registry of adsorbed atoms and molecules on surfaces. The X-ray Standing Wave (XSW) technique offers a powerful method of locating the positions of atoms and molecules in and on single crystals1. This technique is now being employed with increasing frequency with the availability of x-ray radiation synchrotron sources, but is still underutilized with regards to structural determinations of adsorbates on metal surfaces.When x rays are Bragg-reflected from a crystal, the incident and diffracted waves interfere to set up a standing wave field parallel to and having the same spatial periodicity as the reflecting planes. The exact location of the peaks of this standing wave field shift relative to the atomic scattering planes as one scans through the region of total reflectivity associated with the Bragg condition. By measuring a yield characteristic of a bulk atom or an adsorbate excited by the standing wave field, such as Auger electron emission, core level photoemission, or x-ray fluorescence, the atom's position relative to the diffraction planes can be determined.

Recent results on implosions directly driven at λ = 0·26-μm laser wavelength

New diagnostics were implemented on the implosion experiments performed at LULI to improve our measurements of hydroefficiencies: Neutron chronometry gives the time of emission of the fusion reaction products as measured from the peak of the laser pulse; thereby making it possible to correlate the neutron emission with X-ray emission. Core imaging, based upon a maximum entropy reconstruction technique, leads to core size determination and also is a promising diagnostic for wall nonuniformities induced by irradiation conditions. A simple model is developed to retrieve experimental spectra of α-particles.