Design, development and mechanization of a precision deployable truss with optimized structural efficiency for spaceborne applications

A deployable mast concept which meets the weight, size and stability requirements for a feed support structure for offset antennas up to 100 meters in diameter is discussed. A triangulated truss configuration, the use of tapered tubes which exhibit a high strength-to-weight ratio, and low CTE graphite-epoxy material are seen to provide an efficient, lightweight and stable truss suitable for an antenna feed support. A low stowage ratio of 30:1 is achieved through a unique preloaded hinge located at the center of each longeron and an autonomous deployment cage with a drive mechanism. Initial analysis and proof of concept hardware validated the basic mechanism and design assumptions and provided a basis for further investigation. The concept can readily accept variations in member size and thus lends itself to optimization for other potential uses where a stiff, lightweight deployable truss is needed

Joint for deployable structures

A joint is described for connecting a pair of beams to pivot them between positions in alignment or beside one another, which is of light weight and which operates in a controlled manner. The joint includes a pair of fittings and at least one center link having opposite ends pivotally connected to opposite fittings and having axes that pass through centerplates of the fittings. A control link having opposite ends pivotally connected to the different fittings controls their relative orientations, and a toggle assemly holds the fittings in the deployed configuration wherein they are aligned. The fittings have stops that lie on one side of the centerplane opposite the toggle assembly

Phase-matched second-harmonic generation in a ferroelectric liquid crystal waveguide

True phase-matched second-harmonic generation in a waveguide of crosslinkable ferroelectric liquid crystals is demonstrated. These materials allow the formation of macroscopically polar structures whose order can be frozen by photopolymerization. Homeotropic alignment was chosen which offers decisive advantages compared to other geometries. All parameters contributing to the conversion efficiency are maximized by deliberately controlling the supramolecular arrangement. The system has the potential to achieve practical level of performances as a frequency doubler for low power laser diodes.Comment: 4 pages, LaTeX2e article, 3 figures, 4 EPS files, submitted to Physical Review Letter

Tremorogeni učinci ekstrakata plijesni izoliranih iz prašine drveta u štakora

Among workers in the Swedish wood industry acute alveolitis, known as “woodtrimmer\u27s disease” has been recognized for some time. One of the signs in the acute phase of the disease is transitory tremor. The etiology of the disease is still not clearly understood, but it is assumed to be associated with wood dust containing fungal spores. One of the dominant fungal strains isolated from wood at the saw-mills was found to be Aspergillus fumigatus. As it is known that Aspergillus fumigatus has the ability to produce tremorgenic mycotoxins, the moulds from the working environment were isolated, cultivated and tested for the ability to produce mycotoxins, to estimate a possible relation between fungal spores and tremorgenic effects. Extracts of moulds were prepared and tested on rats after oral administration. The ability to induce tremors in rats was found in six out of nine extracts tested. A very good agreement was found between the results of the chemical analysis of extracts and those of the study in vivo. The results imply that woodtrimmer\u27s disease may at least partly, be mycotoxicosis.U Švedskoj, u radnika zaposlenih u drvnoj industriji, javlja se akutni alveolitis poznat i pod nazivom Woodtrimmer\u27s disease, popraćen prolaznim tremorom. Pojava je nepoznate etiologije ali se povezuje s izloženošću drvenoj prašini u kojoj se nalaze spore različitih plijesni. Aspergillus fumigatus je plijesan koja se najčešće izolira u sušarama drveta. Iz radne sredine izolirane su plijesni Aspergillus flavusa te je nakon kultivacije testirana njihova sposobnost stvaranja tremorogenih mikotoksina analitičkim metodama i u pokusima na štakorima. Ekstrakti plijesni aplicirani su pokusnim životinjama oralno. Šest od devet ekstrakata izazvalo je pojavu tremora u tretiranih životinja. Nađena je vrlo dobra korelacija rezultata kemijskih analiza i rezultata dobivenih u pokusima in vivo. Podaci upućuju na moguću vezu između Woodtrimmer\u27s disease i izloženosti radnika tremorogenim mikotoksinima

A and B antigen levels acquired by group O donor-derived erythrocytes following ABO-non-identical transfusion or minor ABO-incompatible haematopoietic stem cell transplantation

BACKGROUND AND OBJECTIVES: ABO-incompatible haematopoietic stem cell transplantation (HSCT) presents a challenge to blood component transfusion. The aim of this study was to investigate the weak blood group A or B antigen expression by donor-derived group O red blood cells (RBC) observed following transfusion or minor ABO-incompatible HSCT. In addition, in vitro experiments were performed to elucidate possible mechanisms underlying this phenomenon.MATERIALS AND METHODS: A sensitive flow cytometry assay for the semi-quantification of RBC A/B antigen levels was used to assess patient samples and evaluate in vitro experiments.RESULTS: Analysis of blood samples from patients, originally typed as A, B and AB but recently transplanted or transfused with cells from group O donors, revealed the A antigen expression on donor-derived RBC, ranging from very low levels in non-secretor individuals to almost subgroup Ax -like profiles in group A secretors. The B antigen expression was less readily detectable. In vitro experiments, in which group O donor RBC were incubated with (i) group A/B secretor/non-secretor donor plasma or (ii) group A/B donor RBC in the absence of plasma, supported the proposed adsorption of A/B antigen-bearing glycolipids from secretor plasma but also indicated a secretor-independent mechanism for A/B antigen acquisition as well as direct cell-to-cell transfer of ABO antigens.CONCLUSION: The in vivo conversion of donor-derived blood group O RBC to ABO subgroup-like RBC after transfusion or minor ABO-incompatible HSCT raises the question of appropriate component selection. Based on these data, AB plasma should be transfused following ABO-incompatible HSCT

Low-Background gamma counting at the Kimballton Underground Research Facility

The next generation of low-background physics experiments will require the use of materials with unprecedented radio-purity. A gamma-counting facility at the Kimballton Underground Research Facility (KURF) has been commissioned to perform initial screening of materials for radioactivity primarily from nuclides in the 238U and 232Th decay chains, 40K and cosmic-ray induced isotopes. The facility consists of two commercial low-background high purity germanium (HPGe) detectors. A continuum background reduction better than a factor of 10 was achieved by going underground. This paper describes the facility, detector systems, analysis techniques and selected assay results.Comment: 7 pages, 7 figures. Submitted to NIM

Sustainable international business model innovations for a globalizing circular economy : a review and synthesis, integrative framework, and opportunities for future research

The global imperative has increased in recent years for international firms to respond to major threats such as unintended environmental, social, and economic problems arising from ecological destruction, population growth, and economic activity. To respond to this confluence that has created an emerging existential crisis, we identify that a globalizing circular economy (CE) is required and subsequently define a new construct: sustainable international business model innovations. In doing so, we introduce circular inputs, sharing platforms, product as a service, product use extension, and resource recovery as business models that contain the potential to reply to these grand challenges. Based on CE principles, the innovations and designs introduced are contrasted with the traditional linear economic model and are presented as actionable standardization/adaptation alternatives for companies responding to differing informal and formal international institutions. Based on the theoretical underpinnings of the resource-based, dynamic capabilities, and international business model innovation perspectives, we introduce an integrative framework that is accompanied by a series of detailed research questions to provide future research opportunities for the domain. This conceptual approach holds that international resource design influences marketing capabilities adaptation which, in turn, impacts international performance and offers a foundation from which to build the literature.© The Author(s) 2023. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.fi=vertaisarvioitu|en=peerReviewed

A calibration method for broad-bandwidth cavity enhanced absorption spectroscopy performed with supercontinuum radiation

An efficient calibration method has been developed for broad-bandwidth cavity enhanced absorption spectroscopy. The calibration is performed using phase shift cavity ring-down spectroscopy, which is conveniently implemented through use of an acousto-optic tunable filter (AOTF). The AOTF permits a narrowband portion of the SC spectrum to be scanned over the full high-reflectivity bandwidth of the cavity mirrors. After calibration the AOTF is switched off and broad-bandwidth CEAS can be performed with the same light source without any loss of alignment to the set-up. We demonstrate the merits of the method by probing transitions of oxygen molecules O-2 and collisional pairs of oxygen molecules (O-2)(2) in the visible spectral range

Unified Treatment of Asymptotic van der Waals Forces

In a framework for long-range density-functional theory we present a unified full-field treatment of the asymptotic van der Waals interaction for atoms, molecules, surfaces, and other objects. The only input needed consists of the electron densities of the interacting fragments and the static polarizability or the static image plane, which can be easily evaluated in a ground-state density-functional calculation for each fragment. Results for separated atoms, molecules, and for atoms/molecules outside surfaces are in agreement with those of other, more elaborate, calculations.Comment: 6 pages, 5 figure