Microstructure and crystal order during freezing of supercooled water drops.

Supercooled water droplets are widely used to study supercooled water1,2, ice nucleation3-5 and droplet freezing6-11. Their freezing in the atmosphere affects the dynamics and climate feedback of clouds12,13 and can accelerate cloud freezing through secondary ice production14-17. Droplet freezing occurs at several timescales and length scales14,18 and is sufficiently stochastic to make it unlikely that two frozen drops are identical. Here we use optical microscopy and X-ray laser diffraction to investigate the freezing of tens of thousands of water microdrops in vacuum after homogeneous ice nucleation around 234-235 K. On the basis of drop images, we developed a seven-stage model of freezing and used it to time the diffraction data. Diffraction from ice crystals showed that long-range crystalline order formed in less than 1 ms after freezing, whereas diffraction from the remaining liquid became similar to that from quasi-liquid layers on premelted ice19,20. The ice had a strained hexagonal crystal structure just after freezing, which is an early metastable state that probably precedes the formation of ice with stacking defects8,9,18. The techniques reported here could help determine the dynamics of freezing in other conditions, such as drop freezing in clouds, or help understand rapid solidification in other materials.

Antioxidant and lipid supplementation improve the development of photoreceptor outer segments in pluripotent stem cell-derived retinal organoids.

The generation of retinal organoids from human pluripotent stem cells (hPSC) is now a well-established process that in part recapitulates retinal development. However, hPSC-derived photoreceptors that exhibit well-organized outer segment structures have yet to be observed. To facilitate improved inherited retinal disease modeling, we determined conditions that would support outer segment development in maturing hPSC-derived photoreceptors. We established that the use of antioxidants and BSA-bound fatty acids promotes the formation of membranous outer segment-like structures. Using new protocols for hPSC-derived retinal organoid culture, we demonstrated improved outer segment formation for both rod and cone photoreceptors, including organized stacked discs. Using these enhanced conditions to generate iPSC-derived retinal organoids from patients with X-linked retinitis pigmentosa, we established robust cellular phenotypes that could be ameliorated following adeno-associated viral vector-mediated gene augmentation. These findings should aid both disease modeling and the development of therapeutic approaches for the treatment of photoreceptor disorders.

Trends in surgical and ablative treatment of localised renal cell carcinoma: A review of publication trends over 16 years (2000-2015).

Objective: To investigate the bibliometric (publication) trends in surgical and ablative treatment of localised renal cell carcinoma (RCC) over a period of 16-years, from 2000 to 2015, as publication trends reflect clinical practice and new innovations. Material and methods: We performed a systematic review using PubMed over a 16-year period from 2000 to 2015 for all published papers on surgical and ablative management of renal tumours. Data were further analysed in two time periods, period-1 (2000-2007) and period-2 (2008-2015). Results: During the last 16 years a total of 2415 papers were published on surgical (n = 1662, 69%) and ablative (n = 753, 31%) management of RCC. This included partial nephrectomy (PN; n = 1662, 69%), cryoablation (CA; n = 405, 17%), and radiofrequency ablation (RFA; n = 348, 14%). When comparing the two time periods for PN, during period-2, the change was +189% (P < 0.001), +69% (P = 0.004) and +4600% (P < 0.001) for open PN, laparoscopic PN and robotic PN, respectively. Regarding ablative techniques, a change of +109% (P = 0.002) and +78% (P = 0.036) was seen for CA and RFA, respectively. There was also a significant rise in percutaneous CA when compared to laparoscopic CA (P < 0.002). Conclusions: There has been a rise in all forms of PN and ablative techniques over the last 16 years. This rise has been particularly steep for robotic PN potentially reflecting a change in surgical practice. Abbreviations: CA: cryoablation; CC: correlation coefficient; MIS: minimally invasive surgery/surgical; NSS: nephron-sparing surgery; (L)(O)(R)PN: (laparoscopic) (open) (robotic) partial nephrectomy; PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses; RFA: radiofrequency ablation; RN: radical nephrectomy; SRM: small renal mass.

The Macromolecular Femtosecond Crystallography Instrument at the Linac Coherent Light Source.

The Macromolecular Femtosecond Crystallography (MFX) instrument at the Linac Coherent Light Source (LCLS) is the seventh and newest instrument at the world's first hard X-ray free-electron laser. It was designed with a primary focus on structural biology, employing the ultrafast pulses of X-rays from LCLS at atmospheric conditions to overcome radiation damage limitations in biological measurements. It is also capable of performing various time-resolved measurements. The MFX design consists of a versatile base system capable of supporting multiple methods, techniques and experimental endstations. The primary techniques supported are forward scattering and crystallography, with capabilities for various spectroscopic methods and time-resolved measurements. The location of the MFX instrument allows for utilization of multiplexing methods, increasing user access to LCLS by running multiple experiments simultaneously.

How Cubic Can Ice Be?

Using an X-ray laser, we investigated the crystal structure of ice formed by homogeneous ice nucleation in deeply supercooled water nanodrops (r ≈ 10 nm) at ∼225 K. The nanodrops were formed by condensation of vapor in a supersonic nozzle, and the ice was probed within 100 µs of freezing using femtosecond wide-angle X-ray scattering at the Linac Coherent Light Source free-electron X-ray laser. The X-ray diffraction spectra indicate that this ice has a metastable, predominantly cubic structure; the shape of the first ice diffraction peak suggests stacking-disordered ice with a cubicity value, χ, in the range of 0.78 ± 0.05. The cubicity value determined here is higher than those determined in experiments with micron-sized drops but comparable to those found in molecular dynamics simulations. The high cubicity is most likely caused by the extremely low freezing temperatures and by the rapid freezing, which occurs on a ∼1 µs time scale in single nanodroplets.

Se-SAD serial femtosecond crystallography datasets from selenobiotinyl-streptavidin.

We provide a detailed description of selenobiotinyl-streptavidin (Se-B SA) co-crystal datasets recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) for selenium single-wavelength anomalous diffraction (Se-SAD) structure determination. Se-B SA was chosen as the model system for its high affinity between biotin and streptavidin where the sulfur atom in the biotin molecule (C10H16N2O3S) is substituted with selenium. The dataset was collected at three different transmissions (100, 50, and 10%) using a serial sample chamber setup which allows for two sample chambers, a front chamber and a back chamber, to operate simultaneously. Diffraction patterns from Se-B SA were recorded to a resolution of 1.9 Å. The dataset is publicly available through the Coherent X-ray Imaging Data Bank (CXIDB) and also on LCLS compute nodes as a resource for research and algorithm development.

Selenium single-wavelength anomalous diffraction de novo phasing using an X-ray-free electron laser.

Structural information about biological macromolecules near the atomic scale provides important insight into the functions of these molecules. To date, X-ray crystallography has been the predominant method used for macromolecular structure determination. However, challenges exist when solving structures with X-rays, including the phase problem and radiation damage. X-ray-free electron lasers (X-ray FELs) have enabled collection of diffraction information before the onset of radiation damage, yet the majority of structures solved at X-ray FELs have been phased using external information via molecular replacement. De novo phasing at X-ray FELs has proven challenging due in part to per-pulse variations in intensity and wavelength. Here we report the solution of a selenobiotinyl-streptavidin structure using phases obtained by the anomalous diffraction of selenium measured at a single wavelength (Se-SAD) at the Linac Coherent Light Source. Our results demonstrate Se-SAD, routinely employed at synchrotrons for novel structure determination, is now possible at X-ray FELs.

The perspectives of stakeholders of intellectual disability liaison nurses: a model of compassionate, person-centred care.

AIMS AND OBJECTIVES: To investigate the experiences of patients with intellectual disabilities, family and paid carers regarding the role of liaison nurses and the delivery of compassionate, person-centred care. From this to propose a model of person-centred care embedded in these experiences. BACKGROUND: People with intellectual disabilities have a high number of comorbidities, requiring multidisciplinary care, and are at high risk of morbidity and preventable mortality. Provision of compassionate, person-centred care is essential to prevent complications and avoid death. DESIGN: A qualitative design was adopted with Interpretative Phenomenological Analysis for data analysis. METHODS: Semistructured interviews and focus groups were conducted. Data were analysed with a focus on compassionate, person-centred care elements and components. Themes were modelled to develop a clinically meaningful model for practice. RESULTS: Themes identified vulnerability, presence and the human interface; information balance; critical points and broken trust; roles and responsibilities; managing multiple transitions; 'flagging up' and communication. CONCLUSIONS: The findings provide the first 'anatomy' of compassionate, person-centred care and provide a model for operationalising this approach in practice. The applicability of the model will have to be evaluated further with this and other vulnerable groups. RELEVANCE TO CLINICAL PRACTICE: This is the first study to provide a definition of compassionate, person-centred care and proposes a model to support its application into clinical practice for this and other vulnerable groups.

The Coherent X-ray Imaging instrument at the Linac Coherent Light Source.

The Coherent X-ray Imaging (CXI) instrument specializes in hard X-ray, in-vacuum, high power density experiments in all areas of science. Two main sample chambers, one containing a 100 nm focus and one a 1 µm focus, are available, each with multiple diagnostics, sample injection, pump-probe and detector capabilities. The flexibility of CXI has enabled it to host a diverse range of experiments, from biological to extreme matter.