Spatial wavefront shaping with a multipolar-resonant metasurface for structured illumination microscopy

Structured illumination microscopy (SIM) achieves superresolution in fluorescence imaging through patterned illumination and computational image reconstruction, yet current methods require bulky, costly modulation optics and high-precision optical alignment. This work demonstrates how nano-optical metasurfaces, rationally designed to tailor the optical wavefront at sub-wavelength dimensions, hold great potential as ultrathin, single-surface, all-optical wavefront modulators for SIM. We computationally demonstrate this principle with a multipolar-resonant metasurface composed of silicon nanostructures which generate versatile optical wavefronts in the far field upon variation of the polarization or angle of incident light. Algorithmic optimization is performed to identify the seven most suitable illumination patterns for SIM generated by the metasurface based on three key criteria. We find that multipolar-resonant metasurface SIM (mrm-SIM) achieves resolution comparable to conventional methods by applying the seven optimal metasurface-generated wavefronts to simulated fluorescent objects and reconstructing the objects using proximal gradient descent. The work presented here paves the way for a metasurface-enabled experimental simplification of structured illumination microscopy.Comment: TR and PTB contributed equally to this wor

Binding of bacteria to poly (N-isopropylacrylamide) modified with vancomycin: Comparison of behavior of linear and highly branched polymers

YesThe behavior of a linear copolymer of N-isopropyl acrylamide with pendant vancomycin functionality was compared to an analogous highly branched copolymer with vancomycin functionality at the chain ends. Highly branched poly(N-isopropylacrylamide) modified with vancomycin (HB-PNIPAM-van) was synthesized by functionalization of the HB-PNIPAM, prepared using reversible addition-fragmentation chain transfer polymerization. Linear PNIPAM with pendant vancomycin functionality (L-PNIPAM-van) was synthesized by functionalization of poly(N-isopropyl acrylamide-co-vinyl benzoic acid). HB-PNIPAM-van aggregated S. aureus effectively whereas the L-PNIPAM-van polymer did not. It was found that when the HB-PNIPAM-van was incubated with S. aureus the resultant phase transition provided an increase in the intensity of fluorescence of a solvatochromic dye, nile red, added to the system. In contrast, a significantly lower increase in fluorescence intensity was obtained when L-PNIPAM-van was incubated with S. aureus. These data showed that the degree of desolvation of HB-PNIPAM-van was much greater than the desolvation of the linear version. Using microCalorimetry it was shown that there were no significant differences in the affinities of the polymer ligands for D-Ala-D-Ala and therefore differences in the interactions with bacteria were associated with changes in the probability of access of the polymer bound ligands to the D-Ala-D-Ala dipeptide. The data support the hypothesis that generation of polymer systems that respond to cellular targets, for applications such as cell targeting, detection of pathogens etc., requires the use of branched polymers with ligands situated at the chain ends.MR

Microscopic motility of isolated E. coli flagella

The fluctuation-dissipation theorem describes the intimate connection between the Brownian diffusion of thermal particles and their drag coefficients. In the simple case of spherical particles, it takes the form of the Stokes-Einstein relationship that links the particle geometry, fluid viscosity, and diffusive behavior. However, studying the fundamental properties of microscopic asymmetric particles, such as the helical-shaped propeller used by $\textit{E. coli}$, has remained out of reach for experimental approaches due to the need to quantify correlated translation and rotation simultaneously with sufficient spatial and temporal resolution. To solve this outstanding problem, we generated volumetric movies of fluorophore-labeled, freely diffusing, isolated $\textit{E. Coli}$ flagella using oblique plane microscopy. From these movies, we extracted trajectories and determined the hydrodynamic propulsion matrix directly from the diffusion of flagella via a generalized Einstein relation. Our results validate prior proposals, based on macroscopic wire helices and low Reynolds number scaling laws, that the average flagellum is a highly inefficient propeller. Specifically, we found the maximum propulsion efficiency of flagella is less than 5%. Beyond extending Brownian motion analysis to asymmetric 3D particles, our approach opens new avenues to study the propulsion matrix of particles in complex environments where direct hydrodynamic approaches are not feasible.Comment: 6 pages, 4 figures, 9 supplemental sections, 7 supplemental figures, 3 supplemental movies *authors contributed equally and reserve the right to change order for first authorshi

Longitudinal Surveillance of Porcine Rotavirus B Strains from the United States and Canada and In Silico Identification of Antigenically Important Sites

Citation: Shepherd, F.K.; Murtaugh, M.P.; Chen, F.; Culhane, M.R.; Marthaler, D.G. Longitudinal Surveillance of Porcine Rotavirus B Strains from the United States and Canada and In Silico Identification of Antigenically Important Sites. Pathogens 2017, 6, 64.Rotavirus B (RVB) is an important swine pathogen, but control and prevention strategies are limited without an available vaccine. To develop a subunit RVB vaccine with maximal effect, we characterized the amino acid sequence variability and predicted antigenicity of RVB viral protein 7 (VP7), a major neutralizing antibody target, from clinically infected pigs in the United States and Canada. We identified genotype-specific antigenic sites that may be antibody neutralization targets. While some antigenic sites had high amino acid functional group diversity, nine antigenic sites were completely conserved. Analysis of nucleotide substitution rates at amino acid sites (dN/dS) suggested that negative selection appeared to be playing a larger role in the evolution of the identified antigenic sites when compared to positive selection, and was identified in six of the nine conserved antigenic sites. These results identified important characteristics of RVB VP7 variability and evolution and suggest antigenic residues on RVB VP7 that are negatively selected and highly conserved may be good candidate regions to include in a subunit vaccine design due to their tendency to remain stable

HL‐TWiM Empirical Model of High‐Latitude Upper Thermospheric Winds

We present an empirical model of thermospheric winds (High‐latitude Thermospheric Wind Model [HL‐TWiM]) that specifies F region high‐latitude horizontal neutral winds as a function of day of year, latitude, longitude, local time, and geomagnetic activity. HL‐TWiM represents the large‐scale neutral wind circulation, in geomagnetic coordinates, for the given input conditions. The model synthesizes the most extensive collection to date of historical high‐latitude wind measurements; it is based on statistical analyses of several decades of F region thermospheric wind measurements from 21 ground‐based stations (Fabry‐Perot Interferometers and Scanning Doppler Imaging Fabry‐Perot Interferometers) located at various northern and southern high latitudes and two space‐based instruments (UARS WINDII and GOCE). The geomagnetic latitude and local time dependences in HL‐TWiM are represented using vector spherical harmonics, day of year and longitude variations are represented using simple harmonic functions, and the geomagnetic activity dependence is represented using quadratic B splines. In this paper, we describe the HL‐TWiM formulation and fitting procedures, and we verify the model against the neutral wind databases used in its formulation. HL‐TWiM provides a necessary benchmark for validating new wind observations and tuning our physical understanding of complex wind behaviors. Results show stronger Universal Time variation in winds at southern than northern high latitudes. Model‐data intra‐annual comparisons in this study show semiannual oscillation‐like behavior of GOCE winds, rarely observed before in wind data.Key PointsWe developed a comprehensive empirical model of high‐latitude F region thermospheric winds (HL‐TWiM)Universal Time variations in high‐latitude winds are stronger in the Southern than Northern HemisphereHL‐TWiM provides a necessary benchmark for validating new high‐latitude wind observations and tuning first principal modelsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153588/1/jgra55363_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153588/2/jgra55363-sup-0001-Figure_SI-S01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153588/3/jgra55363.pd

Branched amphotericin functional poly(N-isopropyl acrylamide): an antifungal polymer

Branched poly(N-isopropylacrylamide) was functionalized with Amphotericin B (AmB) at the chain ends to produce an antifungal material. The polymer showed antifungal properties against AmB-sensitive strains of Candida albicans, Fusarium keratoplasticum and Aspergillus flavus (minimal inhibitory concentration ranged from 5 to 500 µg ml−1) but was not effective against an AmB resistant strain of C. albicans nor against Candida tropicalis. The polymer end groups bound to the AmB target, ergosterol, and the fluorescence spectrum of a dye used as a solvatochromic probe, Nile red, was blue shifted indicating that segments of the polymer became desolvated on binding. The polymer was less toxic to corneal and renal epithelial cells and explanted corneal tissue than the free drug. Also, the polymer did not induce reactive oxygen species release from peripheral blood mononuclear cells, nor did it cause a substantial release of the proinflammatory cytokines, tumour necrosis factor-α and interleukin-1β (at 0.5 mg ml−1)

Academic self-concept, gender and single-sex schooling

This paper assesses gender differences in academic self-concept for a cohort of children born in 1958 (the National Child Development Study). We address the question of whether attending single-sex or co-educational schools affected students’ perceptions of their own academic abilities (academic self-concept). Academic selfconcept was found to be highly gendered, even controlling for prior test scores. Boys had higher self-concepts in maths and science, and girls in English. Single-sex schooling reduced the gender gap in self-concept, while selective schooling was linked to lower academic self-concept overall

Antibiotic functionalised polymers reduce bacterial biofilm and bioburden in a simulated infection of the cornea

Microbial keratitis can arise from penetrating injuries to the cornea. Corneal trauma promotes bacterial attachment and biofilm growth, which decrease the effectiveness of antimicrobials against microbial keratitis. Improved therapeutic efficacy can be achieved by reducing microbial burden prior to antimicrobial therapy. This paper assesses a highly-branched poly(N-isopropyl acrylamide) with vancomycin end groups (HB-PNIPAM-van), for reducing bacterial attachment and biofilm formation. The polymer lacked antimicrobial activity against Staphylococcus aureus, but significantly inhibited biofilm formation (p = 0.0008) on plastic. Furthermore, pre-incubation of S. aureus cells with HB-PNIPAM-van reduced cell attachment by 50% and application of HB-PNIPAM-van to infected ex vivo rabbit corneas caused a 1-log reduction in bacterial recovery, compared to controls (p = 0.002). In conclusion, HB-PNIPAM-van may be a useful adjunct to antimicrobial therapy in the treatment of corneal infections

Differences in anti-malarial activity of 4-aminoalcohol quinoline enantiomers and investigation of the presumed underlying mechanism of action

International audienc

The Cosmic Lens All-Sky Survey: I. Source selection and observations

The Cosmic Lens All-Sky Survey (CLASS) is an international collaborative program which has obtained high-resolution radio images of over 10000 flat-spectrum radio sources in order to create the largest and best studied statistical sample of radio-loud gravitationally lensed systems. With this survey, combined with detailed studies of the lenses found therein, constraints can be placed on the expansion rate, matter density, and dark energy (e.g. cosmological constant, quintessence) content of the Universe that are complementary to and independent of those obtained through other methods. CLASS is aimed at identifying lenses where multiple images are formed from compact flat-spectrum radio sources, which should be easily identifiable in the radio maps. Because CLASS is radio-based, dust obscuration in lensing galaxies is not a factor, and the relative insensitivity of the instrument to environmental conditions leads to nearly uniform sensitivity and resolution over the entire survey. In four observing seasons from 1994-1999, CLASS has observed 13783 radio sources with the VLA at 8.4 GHz at 0.2 arcsecond resolution. When combined with the JVAS survey, the CLASS sample contains over 16,000 images. A complete sample of 11685 flat-spectrum sources was observed, selected from GB6 catalogue at 4.85 GHz and the NVSS at 1.4 GHz. So far, CLASS has found 16 new gravitational lens systems, and the JVAS/CLASS survey contains a total of 22 lenses. (Abridged)Comment: 14 pages, 9 figures, accepted for publication in MNRA