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

Isolated optical vortex knots

Natural and artificially created light fields in three-dimensional space contain lines of zero intensity, known as optical vortices. Here, we describe a scheme to create optical beams with isolated optical vortex loops in the forms of knots and links using algebraic topology. The required complex fields with fibred knots and links are constructed from abstract functions with braided zeros and the knot function is then embedded in a propagating light beam. We apply a numerical optimization algorithm to increase the contrast in light intensity, enabling us to observe several optical vortex knots. These knotted nodal lines, as singularities of the wave’s phase, determine the topology of the wave field in space, and should have analogues in other three-dimensional wave systems such as superfluids5 and Bose–Einstein condensates

Oral Chronic Graft-versus-Host Disease in Pediatric Patients after Hematopoietic Stem Cell Transplantation

AbstractChronic graft-versus-host disease (cGVHD) is a serious and potentially life-threatening complication of hematopoietic stem cell transplantation. This study, which is the largest single-center series of oral disease in pediatric patients with cGVHD, describes the oral findings in 49 consecutive patients seen in a pediatric multidisciplinary cGVHD clinic. All consecutive patients seen at the multidisciplinary pediatric hematopoietic stem cell transplantation/cGVHD clinic at the Dana-Farber Cancer Institute (Boston, MA) from July 2001 through October 2003 were included in this study. Subjective and objective assessments of mucosal, salivary gland, and sclerotic pathology were performed for each patient, and specific therapy was initiated when indicated. Oral mucosal cGVHD was identified in 22 (45%) of 49 patients. Only 4 (8%) of 49 patients reported mouth pain, and all patients reported being able to eat well. All patients who required specific therapy for their oral mucosal cGVHD (45%) were already taking at least 1 immunomodulatory agent; however, efficacy of treatment was difficult to assess because of inconsistent follow-up periods. Subjective and objective salivary gland and sclerotic disease were observed far less often. Oral mucosal pathology is common in these patients, and appropriate diagnosis and management of oral lesions is critical to reduce patient morbidity and to improve quality of life. The apparent lack of salivary gland involvement was notable. Developing validated age-appropriate evaluation strategies and identifying effective treatment guidelines will be invaluable in the future management of these patients