Focussed Ion Beam (FIB) milling is a mainstay of nano-scale machining. By manipulating a tightly focussed beam of energetic ions, often gallium (Ga+), FIB can sculpt nanostructures via localised sputtering. This ability to cut solid matter on the nano-scale revolutionised sample preparation across the life, earth and materials sciences. Despite its widespread usage, detailed understanding of the FIB-induced structural damage, intrinsic to the technique, remains elusive. Here we examine the defects caused by FIB in initially pristine objects. Using Bragg Coherent X-ray Diffraction Imaging (BCDI), we are able to spatially-resolve the full lattice strain tensor in FIB-milled gold nano-crystals. We find that every use of FIB causes large lattice distortions. Even very low ion doses, typical of FIB imaging and previously thought negligible, have a dramatic effect. Our results are consistent with a damage microstructure dominated by vacancies, highlighting the importance of free-surfaces in determining which defects are retained. At larger ion fluences, used during FIB-milling, we observe an extended dislocation network that causes stresses far beyond the bulk tensile strength of gold. These observations provide new fundamental insight into the nature of the damage created and the defects that lead to a surprisingly inhomogeneous morphology.

Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolution beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub-30-nm resolution structural images and ∼90-nm-resolution fluorescence images of several elements in frozen-hydrated green algae. This combined approach offers a way to study the role of trace elements in their structural context. ptychography | X-ray fluorescence microscopy | cryogenic biological samples X -ray fluorescence microscopy (XFM) offers unparalleled sensitivity for quantitative mapping of elements, especially trace metals which play a critical role in many biological processes (1-3). It is complementary to light microscopy, which can study some elemental content in live cells (with superresolution techniques possible) but which is more difficult to quantitate because it depends on the binding affinities of fluorophores. However, XFM does not usually show much cellular ultrastructure, because the light elements (such as H, C, N, and O, which are the main constituents of biological materials) have low fluorescence yield (4). At the multi-keV X-ray energies needed to excite most X-ray fluorescence lines of interest, these light elements show little absorption contrast, but phase contrast can be used to image cellular structure (5, 6) and this can be combined with scanned-beam XFM (7-11).One can also acquire phase-contrast X-ray images with a resolution beyond X-ray lens limits by recording the diffraction pattern from a coherently illuminated, noncrystalline sample in an approach called coherent diffraction imaging (CDI) (12). This approach has been used to image isolated dried cells (13-15), and 3-nm resolution has been achieved when imaging silver nanocubes (16). The traditional CDI approach requires that samples meet a so-called "finite support" (17) requirement with no observable scattering outside of a defined region; although some limited success has been obtained (18,19), this finite support condition has proven difficult to achieve with single cells surrounded by ice layers. Ptychography (20-22) is a recently realized CDI method [with an older history (23)] that circumvents this isolated cell requirement by instead scanning a limitedsize coherent illumination spot across the sample. Ptychography has been used to image freeze-dried diatoms at 30-nm resolution (24) and bacter...

Despite the rapid development of frustrated Lewis pair (FLP) chemistry over the last ten years, its application in catalytic hydrogenations remains dependent on a narrow family of structurally similar early main‐group Lewis acids (LAs), inevitably placing limitations on reactivity, sensitivity and substrate scope. Herein we describe the FLP‐mediated H2 activation and catalytic hydrogenation activity of the alternative LA iPr3SnOTf, which acts as a surrogate for the trialkylstannylium ion iPr3Sn+, and is rapidly and easily prepared from simple, inexpensive starting materials. This highly thermally robust LA is found to be competent in the hydrogenation of a number of different unsaturated functional groups (which is unique to date for main‐group FLP LAs not based on boron), and also displays a remarkable tolerance to moisture.

Biological control of toxigenic Aspergillus flavus in maize through competitive displacement by non-aflatoxigenic strains was evaluated in a series of field studies. Four sets of experiments were conducted between 2007 and 2009 to assess the competitiveness of non-aflatoxigenic strains when challenged against toxigenic strains using a pin-bar inoculation technique. In three sets of experiments the non-aflatoxigenic strain K49 effectively displaced toxigenic strains at various concentrations or combinations. The fourth study compared the relative competitiveness of three non-aflatoxigenic strains (K49, NRRL 21882 from Afla-Guard®, and AF36) when challenged on maize against two aflatoxin- and cyclopiazonic acid (CPA)-producing strains (K54 and F3W4). These studies indicate that K49 and NRRL 21882 are superior to AF36 in reducing total aflatoxin contamination. Neither K49 nor NRRL 21882 produce CPA and when challenged with K54 and F3W4, CPA and aflatoxins were reduced by 84-97% and 83-98%, respectively. In contrast, AF36 reduced aflatoxins by 20% with F3W4 and 93% with K54 and showed no reduction in CPA with F3W4 and only a 62% reduction in CPA with K54. Because AF36 produces CPA, high levels of CPA accumulate when maize is inoculated with AF36 alone or in combination with F3W4 or K54. These results indicate that K49 may be equally effective as NRRL 21882 in reducing both aflatoxins and CPA in maize.

Lattice defects play a key role in determining the properties of crystalline materials. Probing the 3D lattice strains that govern their interactions remains a challenge. Bragg Coherent Diffraction Imaging (BCDI) allows strain to be measured with nano-scale 3D resolution. However, it is currently limited to materials that form micro-crystals. Here we introduce a new technique that allows the manufacture of BCDI samples from bulk materials. Using tungsten as an example, we show that focussed ion beam (FIB) machining can be used to extract, from macroscopic crystals, micron-sized BCDI samples containing specific preselected defects. To interpret the experimental data, we develop a new displacementgradient-based analysis for multi-reflection BCDI. This allows accurate recovery of the full lattice strain tensor from samples containing multiple dislocations. These new capabilities open the door to BCDI as a microscopy tool for studying complex real-world materials.

Ptychography is a coherent diffraction imaging (CDI) method for extended objects in which diffraction patterns are acquired sequentially from overlapping coherent illumination spots. The object's complex transmission function can be reconstructed from those diffraction patterns at a spatial resolution limited only by the scattering strength of the object and the detector geometry. Most experiments to date have positioned the illumination spots on the sample using a move-settle-measure sequence in which the move and settle steps can take longer to complete than the measure step. We describe here the use of a continuous "fly-scan" mode for ptychographic data collection in which the sample is moved continuously, so that the experiment resembles one of integrating the diffraction patterns from multiple probe positions. This allows one to use multiple probe mode reconstruction methods to obtain an image of the object and also of the illumination function. We show in simulations, and in x-ray imaging experiments, some of the characteristics of fly-scan ptychography, including a factor of 25 reduction in the data acquisition time. This approach will become increasingly important as brighter x-ray sources are developed, such as diffraction limited storage rings.

The chemistry of the Group 13 metals is dominated by the +1 and +3 oxidation states, and simple monomeric M(II) species are typically short-lived, highly reactive species. Here we report the first thermally robust monomeric MX2 radicals of gallium, indium and thallium. By making use of sterically demanding boryl substituents, compounds of the type M(II)(boryl)2 (M = Ga, In, Tl) can be synthesized. These decompose above 130 °C and are amenable to structural characterization in the solid state by X-ray crystallography. Electron paramagnetic resonance and computational studies reveal a dominant metal-centred character for all three radicals (>70% spin density at the metal). M(II) species have been invoked as key short-lived intermediates in well-known electron-transfer processes; consistently, the chemical behaviour of these novel isolated species reveals facile one-electron shuttling processes at the metal centre.

Multi-reflection Bragg coherent diffraction imaging has the potential to allow three-dimensional (3D) resolved measurements of the full lattice strain tensor in specific micro-crystals. Until now such measurements were hampered by the need for laborious, time-intensive alignment procedures. Here a different approach is demonstrated, using micro-beam Laue X-ray diffraction to first determine the lattice orientation of the micro-crystal. This information is then used to rapidly align coherent diffraction measurements of three or more reflections from the crystal. Based on these, 3D strain and stress fields in the crystal are successfully determined. This approach is demonstrated on a focused ion beam milled micro-crystal from which six reflections could be measured. Since information from more than three independent reflections is available, the reliability of the phases retrieved from the coherent diffraction data can be assessed. Our results show that rapid, reliable 3D coherent diffraction measurements of the full lattice strain tensor in specific micro-crystals are now feasible and can be successfully carried out even in heavily distorted samples.