Open Access

Show Abstract ▼

Abstract: Mudstone-hosted microfossils are a major component of the Proterozoic fossil record, particularly dominating the record of early eukaryotic life. Early organisms possessed no biomineralized parts to resist decay and controls on their fossilization in mudstones are poorly understood. Consequently, the Proterozoic fossil record is compromised—we do not know whether changing temporal/spatial patterns of microfossil occurrences reflect evolution or the distribution of favourable fossilization conditions. We investigated fossilization within the approximately 1000 Ma Lakhanda Group (Russia) and the approximately 800 Ma Svanbergfjellet and Wynniatt formations (Svalbard and Arctic Canada). Vertical sections of microfossils and surrounding matrices were extracted from thin sections by focused ion beam milling. Elemental mapping and synchrotron-based infrared microspectroscopy revealed that microfossils are surrounded by haloes rich in aluminium, probably hosted in kaolinite. Kaolinite has been implicated in Cambrian Burgess Shale-type (BST) fossilization and is known to slow the growth of degraders. The Neoproterozoic mudstone microfossil record may be biased to tropical settings conducive to kaolinite formation. These deposits lack metazoan fossils even though they share fossilization conditions with younger BST deposits that are capable of preserving non-mineralizing metazoans. Thus metazoans, at least those typically preserved in BST deposits, were probably absent from sedimentary environments before approximately 800 Ma.

Open Access

Show Abstract ▼

Abstract: Vibrational microspectroscopy via Fourier transform infrared (FTIR) faces an experimental trade-off among the signal to noise ratio (SNR), acquisition time, spatial resolution, and sample coverage. This is mainly associated with broadband source type: e.g. low brightness thermal sources with high flux for large field of view imaging at low resolution, or low ´etendue of synchrotron radiation infrared (SRIR) for diffraction-limited scanning mi- croanalysis at high magnification.1 Adaptive optics (AO), in this case deformable mirror (DM), is a potent tool in tackling the problem by modulating the intensity of high brightness structured SRIR beam toward a homo- geneous field illumination for IR imaging at high magnification. The latter is required for an efficient coupling of SRIR source to a multi-pixel detector such as focal plane array (FPA).2 Additionally, DM enables to achieve different shapes, optimized for different Cassegrain IR objective. Regardless, the quality of the generated beam relies upon the performance of the adaptive elements, i.e. actuators and their linear and reproducible response to the applied voltage. Moreover, the beam shaping capability of a single DM in controlling light beam position and angle is limited by its actuators influence function. In this work, we implemented two DMs for intensity shaping for the complex SRIR beam. A variation of multi-conjugate AO is implemented to characterize the performance of DMs and their actuators transfer function at multiple locations. An IR sensitive microbolometer array has been optically conjugated to the focal plane of individual actuators and the far-field of DM, in order to probe the corresponding actuating response. By analysing each actuator’s response individually, a measure of linear independence, uniformity in response, and cross-coupling can be obtained in a spectral range, from visible to near and mid IR. Additionally, by assembling the vectorized version of each actuator response, the transfer matrix can be formed. This matrix describes the relationship between the actuation effect on the beam and the response of the IR microbolometer, at the given conjugate planes. Based on such discussion, we assess the stability of the deformable mirror for open-loop (i.e. without feedback) operation.

Show Abstract ▼

Abstract: Liquid-liquid transitions between two amorphous phases in a single-component liquid have courted controversy. All known examples of liquid–liquid transitions in molecular liquids have been observed in the supercooled state suggesting an intimate connection with vitrification and locally favored structures inhibiting crystallization. However, there is precious little information about the local molecular packing in supercooled liquids meaning that the order parameter of the transition is still unknown. Here, we investigate the liquid–liquid transition in triphenyl phosphite and show that it is caused by the competition between liquid structures that mirror two crystal polymorphs. The liquid–liquid transition is found to be between a geometrically frustrated liquid to a dynamically frustrated glass. These results indicate a general link between polymorphism and polyamorphism and will lead to a much greater understanding of the physical basis of liquid–liquid transitions and allow the systematic discovery of other examples.

Open Access

Show Abstract ▼

Abstract: Broadband infrared nanospectroscopy with Synchrotron Radiation, via the atomic force microscope detection of photothermal expansion, was first demonstrated at the MIRIAM beamline of Diamond in 2016. Since then, the system has undergone significant developments and has been available to users in collaboration since January 2018. Continuous nano-FTIR spectra are so-far achieved with useful signal-to-noise in the 4000 – 800 wavenumber region and at around 100 nm spatial resolution (depending on sample geometry and thermal diffusion at the modulation frequency of the IR beam), for soft materials like single biological cells and polymers. Here we briefly describe the nanospectroscopy system and evaluate the performances through comparison of measured data for typical samples with theoretical expectations. Noise levels are shown to be cantilever thermal-noise limited at the first contact resonance currently employed, whilst signal levels are consistent with expectations for the focussed IR power density available from the IR beamline and using sinusoidal modulation of the beam tuned to the contact resonance frequency. Finally, planned enhancements of the performance, including access to higher cantilever contact resonances to reduce noise and increase spatial resolution, are discussed.

Show Abstract ▼

Abstract: Nanocomposites comprising metal organic frameworks (MOFs) embedded in a polymeric matrix are promising carriers for drug delivery applications. While understanding the chemical and physical transformations of MOFs during the re-lease of confined drug molecules is challenging, this is central to devising better ways for controlled release of therapeutic agents. Herein we demonstrate the efficacy of synchrotron microspectroscopy to track the in situ release of 5-fluorouracil (5-FU) anticancer drug molecules from a drug@MOF/polymer composite (5-FU@HKUST-1/polyurethane). Using experimental time-resolved infrared spectra jointly with newly developed density functional theory calculations, we reveal the detailed dynamics of vibrational motions underpinning the dissociation of 5-FU bound to the framework of HKUST-1 upon water exposure. We discover that HKUST-1 creates hydrophilic channels within the hydrophobic polyurethane matrix hence helping to tune drug release rate. The synergy between a hydrophilic MOF with a hydrophobic polymer can be harnessed to engineer a tunable nanocomposite that alleviates the unwanted burst effect commonly encountered in drug delivery.