University of St Andrews

About: University of St Andrews is a education organization based out in St Andrews, Fife, United Kingdom. It is known for research contribution in the topics: Population & Laser. The organization has 16260 authors who have published 43364 publications receiving 1636072 citations. The organization is also known as: St Andrews University & University of St. Andrews.

Ordered mesoporous Fe2O3 with crystalline walls.

Abstract: α-Fe2O3 has been synthesized with an ordered mesoporous structure and crystalline walls that exhibit a near-single crystal-like order. The unique magnetic behavior of the material, distinct from bulk nanoparticles of α-Fe2O3 or mesoporous Fe2O3 with disordered walls, has been established. Magnetic susceptibility, Mossbauer, and neutron diffraction data show that the material possesses the same long-range magnetic order as bulk α-Fe2O3, despite the wall thickness being less than the 8 nm limit below which magnetic ordering breaks down in nanoparticulate α-Fe2O3, yet the Morin transition of bulk α-Fe2O3 is absent. It is also shown by TEM, PXRD, and EXAFS that α-Fe2O3 with the same ordered mesoporous structure but disordered walls contains small crystalline domains. Mossbauer and magnetic susceptibility data demonstrate that this material exhibits no long-range magnetic order but superparamagnetic behavior.

NK cells and NKT cells collaborate in host protection from methylcholanthrene-induced fibrosarcoma.

Abstract: NK1.1(+) V(alpha)14J(alpha)281(+) (NKT) cells can be induced by IL-12 therapy to mediate tumor rejection; however, methylcholanthrene (MCA)-induced fibrosarcoma is the only tumor model described where NKT cells play a natural role in controlling tumor initiation. From our previous study in C57BL/6 mice it remained unclear whether NK cells were also involved in this natural response. Herein, to discriminate the function of NK and NKT cells, we have evaluated fibrosarcoma development in mice deficient in NKT cells, but not NK cells, and mice deficient in NK cells, but not NKT cells. The results indicate that both NK cells and NKT cells are essential and collaborate in natural host immunity against MCA-induced sarcoma. In contrast, sarcoma incidence and growth rate were reduced using IL-12 therapy, this effect was mediated in the absence of T cells (including NKT cells), but not NK cells.

Switching on electrocatalytic activity in solid oxide cells

Abstract: A new way of activating the electrodes in solid oxide cells involves applying an electrical potential to trigger the exsolution of metal catalysts to the electrode surface; the success of this technique raises the possibility of regenerating the electrodes during operation. Incorporating nanostructured electrodes into solid oxide fuel cells improves performance by increasing the active surface area and therefore increasing electrocatalytic activity. However, fabrication of such electrodes by physical or chemical deposition can be complex. Redox exsolution of nanoparticles from a parent perovskite was shown recently to be a viable means of producing electrodes with enhanced stability. Here, John Irvine and colleagues demonstrate that similar exsolution can be achieved by simply poling the cell for a few seconds, rather than the lengthy redox processes previously used. The resulting cells are highly stable in fuel and electrolysis modes, showing that high-performing electrodes can be fabricated quickly and easily in situ. Solid oxide cells (SOCs) can operate with high efficiency in two ways—as fuel cells, oxidizing a fuel to produce electricity, and as electrolysis cells, electrolysing water to produce hydrogen and oxygen gases. Ideally, SOCs should perform well, be durable and be inexpensive, but there are often competitive tensions, meaning that, for example, performance is achieved at the expense of durability. SOCs consist of porous electrodes—the fuel and air electrodes—separated by a dense electrolyte. In terms of the electrodes, the greatest challenge is to deliver high, long-lasting electrocatalytic activity while ensuring cost- and time-efficient manufacture1. This has typically been achieved through lengthy and intricate ex situ procedures. These often require dedicated precursors and equipment1,2,3; moreover, although the degradation of such electrodes associated with their reversible operation can be mitigated4, they are susceptible to many other forms of degradation5. An alternative is to grow appropriate electrode nanoarchitectures under operationally relevant conditions, for example, via redox exsolution6,7,8,9,10. Here we describe the growth of a finely dispersed array of anchored metal nanoparticles on an oxide electrode through electrochemical poling of a SOC at 2 volts for a few seconds. These electrode structures perform well as both fuel cells and electrolysis cells (for example, at 900 °C they deliver 2 watts per square centimetre of power in humidified hydrogen gas, and a current of 2.75 amps per square centimetre at 1.3 volts in 50% water/nitrogen gas). The nanostructures and corresponding electrochemical activity do not degrade in 150 hours of testing. These results not only prove that in operando methods can yield emergent nanomaterials, which in turn deliver exceptional performance, but also offer proof of concept that electrolysis and fuel cells can be unified in a single, high-performance, versatile and easily manufactured device. This opens up the possibility of simple, almost instantaneous production of highly active nanostructures for reinvigorating SOCs during operation.

Plant communities affect arbuscular mycorrhizal fungal diversity and community composition in grassland microcosms

Abstract: Summary • The diversity of arbuscular mycorrhizal (AM) fungi was investigated in an unfertilized limestone grassland soil supporting different synthesized vascular plant assemblages that had developed for 3 yr. • The experimental treatments comprised: bare soil; monocultures of the nonmycotrophic sedge Carex flacca; monocultures of the mycotrophic grass Festuca ovina; and a species-rich mixture of four forbs, four grasses and four sedges. The diversity of AM fungi was analysed in roots of Plantago lanceolata bioassay seedlings using terminal-restriction fragment length polymorphism (T-RFLP). The extent of AM colonization, shoot biomass and nitrogen and phosphorus concentrations were also measured. • The AM diversity was affected significantly by the floristic composition of the microcosms and shoot phosphorus concentration was positively correlated with AM diversity. The diversity of AM fungi in P. lanceolata decreased in the order: bare soil > C. flacca > 12 species > F. ovina. • The unexpectedly high diversity in the bare soil and sedge monoculture likely reflects differences in the modes of colonization and sources of inoculum in these treatments compared with the assemblages containing established AM-compatible plants.