Nickel-catalysed aromatic Finkelstein reaction of aryl and heteroaryl bromides

A fast and efficient nickel-catalysed iodination reaction of aryl and heteroaryl bromides has been developed. The transformation was found to be general for a wide range of substrates and was used for the synthesis of iodo-PK11195, an imaging agent of Alzheimer's disease and iniparib, a compound used in the treatment of breast cancer.     

Anthraquinone derivatives as electron-acceptors with liquid crystalline properties

Dialkoxy derivatives of anthraquinone (AQ), dicyano-anthraquinone (DCAQ) and tetracyanoanthraquinone (TCAQ) were synthesized and their associated electrochemical, optical and self-assembling properties were investigated as candidates for n-type materials. AQ shows UV absorption features, whereas both DCAQ and TCAQ exhibit bathochromic and hyperchromic electronic transitions into the visible region. The electron accepting strength of the three compounds was established by cyclic voltammetry as -1.52 V, -1.3 V and -0.9 V vs. ferrocene/ferricenium for AQ, DCAQ and TCAQ, respectively. All three quinones displayed quasireversible, two sequential one-electron transfer redox reactions. DFT calculations of DCAQ and TCAQ demonstrate structural changes upon reduction, which is supported by spectroelectrochemical experiments. Furthermore, the structural changes result in different absorption profiles and show potential as electrochromic materials. Finally, both AQ and DCAQ show liquid crystalline phases and importantly, DCAQ exhibits both a smectic liquid crystalline and a soft crystal phase between -6 °C and 85 °C, which offers promise as a self-assembling n-type material.     

Experimental demonstration of relativistic electron cooling

We report on an experimental demonstration of electron cooling of high-energy antiprotons circulating in a storage ring. In our experiments, electron cooling, a well-established method at low energies (<500 MeV/nucleon), was carried out in a new region of beam parameters, requiring a multi-MeV dc electron beam and an unusual beam transport line. In this Letter, we present the results of the longitudinal cooling force measurements and compare them with theoretical predictions.     

How to achieve rapid separations in counter-current chromatography

A new generation of high performance coil planet centrifuges is now making it possible to realize the enormous potential of liquid-liquid partition chromatography for the rapid and predictable scale up of separation processes. This paper uses a separation of flavonoids to demonstrate how rapid fractionations can be obtained at high flow rates with limited loss of resolution and with significant increase in throughput. Furthermore, it is shown that chromatograms at various flows can be modeled so that optimum conditions can be rapidly assessed.     

Gas chromatography with state-of-the-art micromachined differential mobility detection: operation and industrial applications

Ion mobility spectrometry (IMS) has potential analytical applications in very diverse fields such as chemical, petrochemical, environmental, and, more recently, in drug, chemical warfare agent, and explosives detection. Commercially available IMS instruments are based on time-of-flight (TOF) mass spectrometry. IMS is inherently suitable for field operation as it uses relatively simple microfluidic devices and operates at atmospheric pressure. It is portable, highly sensitive with tunable selectivity, yet can be produced at relatively low cost. Key limitations of this analytical detection technique are low duty cycle, ion cluster formation, short linear dynamic range, and restriction to only positive or negative ion collection in a single analysis. Microelectromechanical system, radio frequency modulated IMS (MEMS RF-IMS), also known as differential mobility spectrometry, has recently been developed and commercialized. The technology is based on IMS, and MEMS RF-IMS offers substantially better performance. In this study, the strengths and limitations of the recently introduced differential mobility detector when used with gas chromatography in trace analyses are discussed and illustrated with applications of industrial significance.     

连续波锁模P_r~（3＋）：YLF激光器

本文报导了采用氩离子激光器来泵浦Ｒｒ￣（３＋）：ＹＬＦ晶体，应用声光调制器实现了主动锁模；同时应用振动─高反射平面镜也实现了被动锁模，两种锁模均得到了ｐｓ光脉冲。据作者了解这是这种晶体材料的第一次锁模运转。     

Mössbauer studies on Al−Co ferrites

Mössbauer spectroscopy studies have been performed on the spinel CoAl_xFe_2?xO₄ (2<-x<-1.7) in the temperature range 77–750 K using either a liquid nitrogen bath cryostat or a furnace. The samples are magnetic at 77 K giving spectra that have magnetic sextets coexisting with a central line which increases in population with the Al-content indicating relaxation effects. The data shows that Al possesses no preference to either tetrahedral or octahedral sites of the ferrite over the whole range of concentration. The Mössbauer hyperfine interaction parameters and magnetic transition temperatures were determined. As expected the hyperfine field and Curie temperature decrease when the Al-content increases.