Formation of thermally stable alkylidene layers on a catalytically active surface

Materials containing organic-inorganic interfaces usually display a combination of molecular and solid-state properties, which are of interest for applications ranging from chemical sensing to microelectronics and catalysis. Thiols--organic compounds carrying a SH group--are widely used to anchor organic layers to gold surfaces, because gold is catalytically sufficiently active to replace relatively weak S-H bonds with Au-S bonds, yet too inert to attack C-C and C-H bonds in the organic layer. But although several methods of functionalizing the surfaces of semiconductors, oxides and metals are known, it remains difficult to attach a wide range of more complex organic species. Organic layers could, in principle, be formed on the surfaces of metals that are capable of inserting into strong bonds, but such surfaces catalyse the decomposition of organic layers at temperatures above 400 to 600 K, through progressive C-H and C-C bond breaking. Here we report that cycloketones adsorbed on molybdenum carbide, a material known to catalyse a variety of hydrocarbon conversion reactions, transform into surface-bound alkylidenes stable to above 900 K. We expect that this chemistry can be used to create a wide range of exceptionally stable organic layers on molybdenum carbide.     

爱因斯坦A-Z

本书是一本传记性著作，记述了20世纪最伟大的科学家之一爱因斯坦的生平。与其他传记体文学不同的是，本书别出心裁的以字母表的顺序，以关键词的方式记录了爱因斯坦的生活、科研、理想等等。从第一个单词大大咧咧的（Absentmindeness），一直到最后一个单词犹太复国主义（Zionism）。每个单词作为一章的标题引出了一段或惊险、或平淡的故事。从本书中读者可以了解爱因斯坦在科学方面的天才想法，可以读到他作为普通人生活的一面——一个可怜的丈夫和父亲，还有他在核武器方面的影响，他创造了相对论却拒绝接受量子力学……     

Flares from a candidate Galactic magnetar suggest a missing link to dim isolated neutron stars

Magnetars are young neutron stars with very strong magnetic fields of the order of 10(14)-10(15) G. They are detected in our Galaxy either as soft gamma-ray repeaters or anomalous X-ray pulsars. Soft gamma-ray repeaters are a rare type of gamma-ray transient sources that are occasionally detected as bursters in the high-energy sky. No optical counterpart to the gamma-ray flares or the quiescent source has yet been identified. Here we report multi-wavelength observations of a puzzling source, SWIFT J195509+261406. We detected more than 40 flaring episodes in the optical band over a time span of three days, and a faint infrared flare 11 days later, after which the source returned to quiescence. Our radio observations confirm a Galactic nature and establish a lower distance limit of approximately 3.7 kpc. We suggest that SWIFT J195509+261406 could be an isolated magnetar whose bursting activity has been detected at optical wavelengths, and for which the long-term X-ray emission is short-lived. In this case, a new manifestation of magnetar activity has been recorded and we can consider SWIFT J195509+261406 to be a link between the 'persistent' soft gamma-ray repeaters/anomalous X-ray pulsars and dim isolated neutron stars.     

Very fast optical flaring from a possible new Galactic magnetar

Highly luminous rapid flares are characteristic of processes around compact objects like white dwarfs, neutron stars and black holes. In the high-energy regime of X-rays and gamma-rays, outbursts with variabilities on timescales of seconds or less are routinely observed, for example in gamma-ray bursts or soft gamma-ray repeaters. At optical wavelengths, flaring activity on such timescales has not been observed, other than from the prompt phase of one exceptional gamma-ray burst. This is mostly due to the fact that outbursts with strong, fast flaring are usually discovered in the high-energy regime; most optical follow-up observations of such transients use instruments with integration times exceeding tens of seconds, which are therefore unable to resolve fast variability. Here we show the observation of extremely bright and rapid optical flaring in the Galactic transient SWIFT J195509.6+261406. Our optical light curves are phenomenologically similar to high-energy light curves of soft gamma-ray repeaters and anomalous X-ray pulsars, which are thought to be neutron stars with extremely high magnetic fields (magnetars). This suggests that similar processes are in operation, but with strong emission in the optical, unlike in the case of other known magnetars.