Single molecule light field microscopy

We introduce single molecule light field microscopy (SMLFM), a new class of three-dimensional (3D) single molecule localization microscopy. By segmenting the back focal plane of a microscope objective with an array of microlenses to generate multiple 2D perspective views, the same single fluorophore can be imaged from different angles. These views, in combination with a bespoke fitting algorithm, enable the 3D positions of single fluorophores to be determined from parallax. SMLFM achieves up to 20 nm localization precision throughout an extended 6 µ m depth of field. The capabilities of SMLFM are showcased by imaging membranes of fixed eukaryotic cells and DNA nanostructures below the optical diffraction limit.</jats:p

Accelerating cryoprotectant diffusion kinetics improves cryopreservation of pancreatic islets

Funder: W. D. Armstrong Fund (School of Technology, University of Cambridge)Abstract: Cryopreservation offers the potential to increase the availability of pancreatic islets for treatment of diabetic patients. However, current protocols, which use dimethyl sulfoxide (DMSO), lead to poor cryosurvival of islets. We demonstrate that equilibration of mouse islets with small molecules in aqueous solutions can be accelerated from > 24 to 6 h by increasing incubation temperature to 37 °C. We utilize this finding to demonstrate that current viability staining protocols are inaccurate and to develop a novel cryopreservation method combining DMSO with trehalose pre-incubation to achieve improved cryosurvival. This protocol resulted in improved ATP/ADP ratios and peptide secretion from β-cells, preserved cAMP response, and a gene expression profile consistent with improved cryoprotection. Our findings have potential to increase the availability of islets for transplantation and to inform the design of cryopreservation protocols for other multicellular aggregates, including organoids and bioengineered tissues

Characterization of Irradiated Metal Waste from the Pyrometallurgical Treatment of Used EBR-II Fuel

As part of the pyrometallurgical treatment of used Experimental Breeder Reactor-II fuel, a metal waste stream is generated consisting primarily of cladding hulls laden with fission products noble to the electrorefining process. Consolidation by melting at high temperature [1873 K (1600 degrees C)] has been developed to sequester the noble metal fission products (Zr, Mo, Tc, Ru, Rh, Te, and Pd) which remain in the iron-based cladding hulls. Zirconium from the uranium fuel alloy (U-10Zr) is also deposited on the hulls and forms Fe-Zr intermetallics which incorporate the noble metals as well as residual actinides during processing. Hence, Zr has been chosen as the primary indicator for consistency of the metal waste. Recently, the first production-scale metal waste ingot was generated and sampled to monitor Zr content for Fe-Zr intermetallic phase formation and validation of processing conditions. Chemical assay of the metal waste ingot revealed a homogeneous distribution of the noble metal fission products as well as the primary fuel constituents U and Zr. Microstructural characterization of the ingot confirmed the immobilization of the noble metals in the Fe-Zr intermetallic phase

Closing the Loop: Community Gardening in Boulder, Colorado

Boulder, Colorado has a noticeable and lively community gardening presence. I delved into the question, “What motivates people to be involved in community gardening in Boulder?” In the process of this inquiry, I conducted interviews with thirteen area community gardeners. The narratives of these thirteen gardeners illustrated that Boulder community gardeners come from a variety of backgrounds and participate in gardening for numerous reasons. These reasons include: the desire to be outside, curiosity and experimentation, an interest in sharing resources, a closer connection with one’s food, self-reliance, a commitment to health, and a sense of pride. In order to evaluate the qualitative findings of the interviews, I analyzed the findings through the lens of what I call the four stages of gardening – 1) planning; 2) preparing the land and planting the seeds; 3) weeding, watering, and watching it grow; and 4) eating and sharing food. I found that though the reasons people participate in community gardening are diverse, the gardeners overcome challenges posed by community gardening out of their commitment to cultivating their plots. I hope that this paper can be used to benefit Growing Gardens, the local non-profit organization that supports Boulder community gardens. The examples in this paper of the experiences of community gardeners can perhaps be used in tandem with the quantitative findings of the University of Colorado at Denver’s larger research project for publicity and grant writing purposes

Bicycle infrastructure: can good design encourage cycling?

This research posits the question that good design of the bicycle infrastructure in a city will encourage more people to cycle. Research is carried out to compare the cycle infrastructure in selected European cities against an adapted Level of Service concept using accompanied ride-alongs. The literature review on the factors that encourage/dissuade cycle use suggests that it is the potential rider’s perceptions on the safety of cycling in their neighbourhood that is the deciding feature. Moreover, the literature review showed that contextual factors such as whether the actual infrastructure meets the needs of different cyclists are relatively under-researched. Six case study cities were selected (Edinburgh, Cambridge, Amsterdam, Rotterdam, The Hague, Utrecht) and compared on a range of factors by the riders including the coherence, directness, attractiveness, safety and comfort of the network. A cycle infrastructure scoring system was derived from the cycling research literature and the research was carried out by the researcher, an experienced cyclist, accompanied by an inexperienced cyclist. Using this research, the article makes several recommendations for improving and enhancing existing cycle infrastructure provision

Incoherent-based tunable frequency structured illumination microscopy

A simple illumination system based on a Fresnel biprism illuminated by the diffracted field of an incoherent linear source is experimentally verified for the generation of a 1D structured pattern with a tunable modulation frequency

Illustrations of optical vortices in three dimensions

Optical vortices (phase singularities) arise from interference and are threads of darkness embedded within light fields. Although usually visualised in terms of their points of intersection with an observation plane, appreciation of their true form requires a view in three dimensions. Through numerical simulation we re-examine three situations where optical vortex lines evolve as an additional parameter is varied. Our specific examples are: the addition of a fourth plane wave of varying amplitude into a superposition of three plane waves, the increase of height of a non-integer spiral phase step, and finally the perturbation that creates, and then dissolves, a vortex link in a specific combination of Laguerre-Gauss modes