Chemical vapor deposited silica coatings for solar mirror protection

A variety of techniques is available to apply protective coatings to oxidation susceptible spacecraft components, and each has associated advantages and disadvantages. Film applications by means of chemical vapor deposition (CVD) has the advantage of being able to be applied conformally to objects of irregular shape. For this reason, a study was made of the oxygen plasma durability of thin film (less than 5000 A) silicon dioxide coatings applied by CVD. In these experiments, such coatings were applied to silver mirrors, which are strongly subject to oxidation, and which are proposed for use on the space station solar dynamic power system. Results indicate that such coatings can provide adequate protection without affecting the reflectance of the mirror. Scanning electron micrographs indicated that oxidation of the silver layer did occur at stress crack locations, but this did not affect the measured solar reflectances. Oxidation of the silver did not proceed beyond the immediate location of the crack. Such stress cracks did not occur in thinner silica flims, and hence such films would be desirable for this application

The Outer Galactic Halo As Probed By RR Lyr Stars From the Palomar Transient Facility + Keck

We present initial results from our study of the outer halo of the Milky Way using a large sample of RR Lyr(ab) variables datamined from the archives of the Palomar Transient Facility. Of the 464 RR Lyr in our sample with distances exceeding 50 kpc, 62 have been observed spectroscopically at the Keck Observatory. v _r and σ(v_r) are given as a function of distance between 50 and 110 kpc, and a very preliminary rather low total mass for the Milky Way out to 110 kpc of ~7 ± 1.5 × 10^(11) M⊙ is derived from our data

The Spaces We Make

https://scholarworks.boisestate.edu/mfa_artists_2019/1000/thumbnail.jp

LIGNIN MAXIMIZATION: ANALYZING THE IMPACT OF DIFFERENT FEEDSTOCKS AND FEEDSTOCK RATIOS USING ORGANOSOLV FRACTIONATION

Over-exploitation of fossil fuels coupled with increasing pressure to reduce carbon emissions are prompting a transition from conventional petrochemical feedstocks to sustainable and renewable sourced carbon. The use of lignocellulosic biomass as a feedstock for integrated biorefining is of current high interest, as separation into its component parts affords process streams of cellulose, hemicellulose and lignin, each of which can serve as a starting point for the production of biobased chemicals and fuels. Given the large number of potential sources of lignocellulosic feedstocks, the biorefinery will need to adapt to the supplies available over a normal growing season. Of particular importance is the lignin fraction, as its conversion to chemicals and materials to allow economic viability of the operation. Previous work has demonstrated that organosolv fractionation effectively separates lignocellulosic biomass into its component parts. In this project, we investigated the use of organosolv technology for separating mixtures of lignocellulosic feedstocks to isolate pure lignin. Mixtures of switchgrass (Panicum virgatum), southern yellow pine (Pinus taeda L.), and hybrid poplar (Populus spp.) were separated using organosolv fractionation. Experiments were performed by heating the feedstock mixtures at 150oC in a 3.5 L flow-through reactor with a ternary, one-phase solvent mixture of methyl isobutylketone (MIBK), ethanol (EtOH) and water (H2O) in a wt% ratio of 16/34/50, and containing sulfuric acid as a catalyst. The impact of different process variables was examined by experimental design (‘Design of Experiments’) to minimize the number of experimental runs using a balanced approach in the response surface to maximize inference. The process variables included two different runtimes (60, 120 min), two different sulfuric acid levels (0.05, 0.15 M), and four different wt% feedstock ratios for switchgrass/pine/poplar ([10/10/80], [10/80/10], [80/10/10], [33/33/33]). After completion of the initial experimental matrix, four additional center-points were carried out using a 90 min runtime, and 0.1 M acid level to validate the results for each of the four feedstock ratios. The dependent factors were lignin yield, lignin purity, and cellulose purity. Response surface methodology (RSM) was used to evaluate the impact of the process variables and to determine optimization settings for the process

Ultra-bright and efficient single photon generation based on N-V centres in nanodiamonds on a solid immersion lens

Single photons are fundamental elements for quantum information technologies such as quantum cryptography, quantum information storage and optical quantum computing. Colour centres in diamond have proven to be stable single photon sources and thus essential components for reliable and integrated quantum information technology. A key requirement for such applications is a large photon flux and a high efficiency. Paying tribute to various attempts to maximise the single photon flux we show that collection efficiencies of photons from colour centres can be increased with a rather simple experimental setup. To do so we spin-coated nanodiamonds containing single nitrogen-vacancy colour centres on the flat surface of a ZrO2 solid immersion lens. We found stable single photon count rates of up to 853 kcts/s at saturation under continuous wave excitation while having excess to more than 100 defect centres with count rates from 400 kcts/s to 500 kcts/s. For a blinking defect centre we found count rates up to 2.4 Mcts/s for time intervals of several ten seconds. It seems to be a general feature that very high rates are accompanied by a blinking behaviour. The overall collection efficiency of our setup of up to 4.2% is the highest yet reported for N-V defect centres in diamond. Under pulsed excitation of a stable emitter of 10 MHz, 2.2% of all pulses caused a click on the detector adding to 221 kcts/s thus opening the way towards diamond based on-demand single photon sources for quantum applications

Love Motivates All Things: An Analysis of Peter Banholzer\u27s 2013 Production of A View from the Bridge

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Eagle Mountain Observatory: Eagle Mountain, Minnesota

Our contemporary understanding of the universe has become a rational and systematic science, separating man as a casual onlooker in the scheme. Ancient man on the other hand, believed the universe to be a delicate balance of earth, sky, and man. The blending of these three elements lends a richness that is absent in our modem interpretation..