Deposition and spectral performance of an inhomogeneous broadband wide-angular antireflective coating

The gradient index coatings and optical filters based on them are a challenge for fabrication. In a round-robin experiment basically the same hybrid antireflection coating for the visible spectral region has been deposited with three different techniques: electron beam evaporation, ion beam sputtering and radio frequency magnetron-sputtering. Spectral performances of such one-side and both-side coated samples have been compared with corresponding theoretical spectra of the designed profile. Also, reproducibility of each process is checked

The methodological quality is insufficient in clinical practice guidelines in the context of COVID-19 : systematic review

Objectives The number of published clinical practice guidelines related to COVID-19 has rapidly increased. This study explored if basic methodological standards of guideline development have been met in the published clinical practice guidelines related to COVID-19. Study Design and Setting Rapid systematic review from February 1 until April 27, 2020 using MEDLINE [PubMed], CINAHL [Ebsco], Trip and manual search, including all types of healthcare workers providing any kind of healthcare to any patient population in any setting. Results There were 1342 titles screened and 188 guidelines included. The highest average AGREE II domain score was 89% for scope and purpose, the lowest for rigor of development (25%). Only eight guidelines (4%) were based on a systematic literature search and a structured consensus process by representative experts (classified as the highest methodological quality). The majority (156; 83%) was solely built on an informal expert consensus. A process for regular updates was described in 27 guidelines (14%). Patients were included in the development of only one guideline. Conclusion Despite clear scope, most publications fell short of basic methodological standards of guideline development. Clinicians should use guidelines that include up-to-date information, were informed by stakeholder involvement, and employed rigorous methodologies

Genetic Variation in Jasmonic Acid- and Spider Mite-Induced Plant Volatile Emission of Cucumber Accessions and Attraction of the Predator Phytoseiulus persimilis

Cucumber plants (Cucumis sativus L.) respond to spider–mite (Tetranychus urticae) damage with the release of specific volatiles that are exploited by predatory mites, the natural enemies of the spider mites, to locate their prey. The production of volatiles also can be induced by exposing plants to the plant hormone jasmonic acid. We analyzed volatile emissions from 15 cucumber accessions upon herbivory by spider mites and upon exposure to jasmonic acid using gas chromatography—mass spectrometry. Upon induction, cucumber plants emitted over 24 different compounds, and the blend of induced volatiles consisted predominantly of terpenoids. The total amount of volatiles was higher in plants treated with jasmonic acid than in those infested with spider mites, with (E)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-α-farnesene, and (E)-β-ocimene as the most abundant compounds in all accessions in both treatments. Significant variation among the accessions was found for the 24 major volatile compounds. The accessions differed strongly in total amount of volatiles emitted, and displayed very different odor profiles. Principal component analysis performed on the relative quantities of particular compounds within the blend revealed clusters of highly correlated volatiles, which is suggestive of common metabolic pathways. A number of cucumber accessions also were tested for their attractiveness to Phytoseiulus persimilis, a specialist predator of spider mites. Differences in the attraction of predatory mites by the various accessions correlated to differences in the individual chemical profiles of these accessions. The presence of genetic variation in induced plant volatile emission in cucumber shows that it is possible to breed for cucumber varieties that are more attractive to predatory mites and other biological control agents

Optical and structural properties of LaF3 thin films

LaF3 thin films of different thicknesses were deposited on CaF2 (111) and silicon substrates by boat evaporation at a relatively low substrate temperature of 150°C. Optical and mechanical properties have been investigated and are discussed

Cryopreservation of Phaeocystis antarctica.

A large number of clonal isolates of the prymnesiophyte Phaeocystis antarctica have been established at the Alfred Wegener Institute in Bremerhaven, Germany, to address questions on the genetic diversity and ecological response patterns to climate change. However, at present the wider scientific community cannot access these strains and their long-term conservation, (currently by serial transfer), cannot be assured. Cryopreservation could provide the solution to these issues, as it would guarantee the long-term security of this genetically and ecological invaluable collection. This study outlines the successful application of conventional approaches and the use of novel, combined non-penetrating and penetrating cryoprotective strategies that have been successfully applied to the different life-stages of this alga

Properties chirped mirrors manufactured by plasma assisted electron beam evaporation

Nowadays, chirped dielectric mirrors for ultrafast optics and laser applications are usually manufactured by sputtering techniques. The suitability of Advanced Plasma Source (APS) assisted electron beam evaporation with respect to such coatings is still under investigation. The purpose of this presentation is to show our first results of the deposition of chirped layers produced by plasma ion assisted electron beam evaporation and of the investigation of their properties. The aim was to design and prepare a NIR-mirror for the spectral range of 700 nm to 900 nm. It has been attempted to find a design that is robust with respect to errors of thickness and refractive index. The mirror consists of more than 26 layers composed of alternating high- (Nb2O 5) and low-refractive index (SiO2) material. The deposited coatings were tested in terms of their group delay dispersion (GDD) and their reflectivity. We show, that in the wavelength range between 720 nm and 890 nm the GDD exhibits a value of about -50 fs2, whereas the reflectivity is above 99%. However, the subsequent reverse engineering operations show a relatively large thickness error of more than 1% - 2% regarding the particular layers. Nevertheless the effect on the GDD and the reflectivity is tolerable. Furthermore, we present our first experiments concerning the design and fabrication of a chirped mirror, which allows controlling the third order dispersion (TOD), whereas the relative thickness error of the particular layers should not exceed 1%

A hybrid algorithm for reengineering the refractive index profile for inhomogeneous coatings from optical in-situ broadband monitoring data

Reengineering the refractive index profile of inhomogeneous coatings is a troublesome task. Multiplicity of solutions may significantly reduced by providing additional information. For this reason an in-situ broadband monitoring system was developed to measure the transmittance of the growing film directly at the rotating substrate. For characterization of these coatings a new model was developed, which significantly reduces the number of parameters. The refractive index profile may be described by a proper number of equally spaced volume fraction values using the Bruggeman effective media approach. A good initial approximation of the refractive index profile can be generated based an deposition rates for both materials recorded with quartz crystals monitor during manufacturing. During the optimisation process, a second order minimization algorithm was used to vary the refractive index profile of the whole coating and film thickness of the intermediate stages. Finally, a significantly improved accuracy of the modelled transmittance was achieve