Characterization of membrane proteins is challenging due to the difficulty in mimicking the native lipid bilayer with properly folded and functional membrane proteins. Recently, styrene-maleic acid ...(StMA) copolymers have been shown to facilitate the formation of disc-like lipid bilayer mimetics that maintain the structural and dynamic integrity of membrane proteins. Here we report the controlled synthesis and characterization of StMA containing block copolymers. StMA polymers with different compositions and molecular weights were synthesized and characterized by size exclusion chromatography (SEC). These polymers act as macromolecular surfactants for 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1′-rac-glycerol (POPG) lipids, forming disc like structures of the lipids with the polymer wrapping around the hydrophobic lipid edge. A combination of dynamic light scattering (DLS), solid-state nuclear magnetic resonance (SSNMR) spectroscopy, and transmission electron microscopy (TEM) was used to characterize the size of the nanoparticles created using these StMA polymers. At a weight ratio of 1.25:1 StMA to lipid, the nanoparticle size created is 28+1nm for a 2:1 ratio, 10+1nm for a 3:1 StMA ratio and 32+1nm for a 4:1 StMA ratio independent of the molecular weight of the polymer. Due to the polymer acting as a surfactant that forms disc like nanoparticles, we term these StMA based block copolymers “RAFT SMALPs”. RAFT SMALPs show promise as a new membrane mimetic with different nanoscale sizes, which can be used for a wide variety of biophysical studies of membrane proteins.
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•RAFT polymerization has been used to synthesize styrene-maleic acid copolymers.•Styrene-maleic acid (SMA) polymers can be made with different molar ratios.•SMA polymers upon incorporation with lipids can make stable nanoparticles (SMALPS).•The particle size of SMALPS are independent of the chain length of the polymer.•SMALP nanoparticle size depends only on the SMA ratio (e.g. 2:1, 3:1 or 4:1).
Photonic technologies offer numerous functionalities that can be used to realize astrophotonic
instruments. The most spectacular example to date is the ESO Gravity instrument at the Very Large
...Telescope in Chile that combines the light-gathering power of four 8 m telescopes through a
complex photonic interferometer. Fully integrated astrophotonic devices stand to offer critical
advantages for instrument development, including extreme miniaturization when operating at the
diffraction-limit, as well as integration, superior thermal and mechanical stabilization owing to the
small footprint, and high replicability offering significant cost savings. Numerous astrophotonic
technologies have been developed to address shortcomings of conventional instruments to date,
including for example the development of photonic lanterns to convert from multimode inputs to
single mode outputs, complex aperiodic fiber Bragg gratings to filter OH emission from the
atmosphere, complex beam combiners to enable long baseline interferometry with for example,
ESO Gravity, and laser frequency combs for high precision spectral calibration of spectrometers.
Despite these successes, the facility implementation of photonic solutions in astronomical
instrumentation is currently limited because of (1) low throughputs from coupling to fibers,
coupling fibers to chips, propagation and bend losses, device losses, etc, (2) difficulties with scaling
to large channel count devices needed for large bandwidths and high resolutions, and (3) efficient
integration of photonics with detectors, to name a few. In this roadmap, we identify 24 key areas
that need further development. We outline the challenges and advances needed across those areas
covering design tools, simulation capabilities, fabrication processes, the need for entirely new
components, integration and hybridization and the characterization of devices. To realize these
advances the astrophotonics community will have to work cooperatively with industrial partners
who have more advanced manufacturing capabilities. With the advances described herein,
multi-functional integrated instruments will be realized leading to novel observing capabilities for
both ground and space based platforms, enabling new scientific studies and discoveries.
Photonics offer numerous functionalities that can be used to realize astrophotonic instruments. The most spectacular example to date is the ESO Gravity instrument at the Very Large Telescope in ...Chile. Integrated astrophotonic devices stand to offer critical advantages for instrument development, including extreme miniaturization, as well as integration, superior thermal and mechanical stabilization owing to the small footprint, and high replicability offering cost savings. Numerous astrophotonic technologies have been developed to address shortcomings of conventional instruments to date, including for example the development of photonic lanterns, complex aperiodic fiber Bragg gratings, complex beam combiners to enable long baseline interferometry, and laser frequency combs for high precision spectral calibration of spectrometers. Despite these successes, the facility implementation of photonic solutions in astronomical instrumentation is currently limited because of (1) low throughputs from coupling to fibers, coupling fibers to chips, propagation and bend losses, device losses, etc, (2) difficulties with scaling to large channel count devices needed for large bandwidths and high resolutions, and (3) efficient integration of photonics with detectors, to name a few. In this roadmap, we identify 24 areas that need further development. We outline the challenges and advances needed across those areas covering design tools, simulation capabilities, fabrication processes, the need for entirely new components, integration and hybridization and the characterization of devices. To realize these advances the astrophotonics community will have to work cooperatively with industrial partners who have more advanced manufacturing capabilities. With the advances described herein, multi-functional instruments will be realized leading to novel observing capabilities for both ground and space platforms.
The fields of Astronomy and Astrophysics are technology limited, where the advent and application of new technologies to astronomy usher in a flood of discoveries altering our understanding of the ...Universe (e.g., recent cases include LIGO and the GRAVITY instrument at the VLTI). Currently, the field of astronomical spectroscopy is rapidly approaching an impasse: the size and cost of instruments, especially multi-object and integral field spectrographs for extremely large telescopes (ELTs), are pushing the limits of what is feasible, requiring optical components at the very edge of achievable size and performance. For these reasons, astronomers are increasingly looking for innovative solutions like photonic technologies that promote instrument miniaturization and simplification, while providing superior performance. Astronomers have long been aware of the potential of photonic technologies. The goal of this white paper is to draw attention to key photonic technologies and developments over the past two decades and demonstrate there is new momentum in this arena. We outline where the most critical efforts should be focused over the coming decade in order to move towards realizing a fully photonic instrument. A relatively small investment in this technology will advance astronomical photonics to a level where it can reliably be used to solve challenging instrument design limitations. For the benefit of both ground and space borne instruments alike, an endorsement from the National Academy of Sciences decadal survey will ensure that such solutions are set on a path to their full scientific exploitation, which may one day address a broad range of science cases outlined in the KSPs.
The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is an extremely modular high-contrast instrument installed on the Subaru telescope in Hawaii. SCExAO has a dual purpose. Its ...position in the northern hemisphere on a 8-meter telescope makes it a prime instrument for the detection and characterization of exoplanets and stellar environments over a large portion of the sky. In addition, SCExAO's unique design makes it the ideal instrument to test innovative technologies and algorithms quickly in a laboratory setup and subsequently deploy them on-sky. SCExAO benefits from a first stage of wavefront correction with the facility adaptive optics AO188, and splits the 600-2400 nm spectrum towards a variety of modules, in visible and near infrared, optimized for a large range of science cases. The integral field spectrograph CHARIS, with its J, H or K-band high-resolution mode or its broadband low-resolution mode, makes SCExAO a prime instrument for exoplanet detection and characterization. Here we report on the recent developments and scientific results of the SCExAO instrument. Recent upgrades were performed on a number of modules, like the visible polarimetric module VAMPIRES, the high-performance infrared coronagraphs, various wavefront control algorithms, as well as the real-time controller of AO188. The newest addition is the 20k-pixel Microwave Kinetic Inductance Detector (MKIDS) Exoplanet Camera (MEC) that will allow for previously unexplored science and technology developments. MEC, coupled with novel photon-counting speckle control, brings SCExAO closer to the final design of future high-contrast instruments optimized for Giant Segmented Mirror Telescopes (GSMTs).
We gave pergolide mesylate, a new long-acting ergot derivative with dopaminergic properties, to 47 patients with hypersecretion of prolactin or growth hormone. Single doses produced long-lasting ...reductions of serum prolactin levels; after 24 hours, the values remained depressed at a mean of 28.8 per cent of the base-line value. Among 41 patients (22 women and 19 men) with hyperprolactinemia who took pergolide for three months or more, prolactin levels fell to normal in 37 and remained slightly elevated in 2. In the two patients in whom the levels fell to only 38 to 52 per cent of base line, treatment was regarded as a failure. The level of growth hormone fell to a mean of 52.8 per cent of base line in patients with acromegaly who were taking 100 micrograms of pergolide per day. Among patients for whom adequate CT scans were available, definite tumor shrinkage occurred in 10 of 13 with macroadenomas and definite or probable shrinkage in 5 of 9 with microadenomas. Menses returned in 76 per cent of treated women and testosterone levels rose in 10 of 14 men. We conclude that pergolide reduces hypersecretion and shrinks most prolactin-secreting macroadenomas. In some patients long-term pergolide therapy may be superior to surgery and x-ray treatment.
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