Sun-synchronous highly elliptical orbits using low-thrust propulsion

Due to restrictions within the current architecture of the global observing system (GOS), space-based remote sensing of Earth suffers from an acute data-deficit over the critical polar-regions. Currently, observation of high-latitude regions is conducted using composite images from spacecraft in geostationary (GEO) and low-Earth orbits (LEOs) [1]. However, the oblique viewing geometry from GEO-based systems to latitudes above around 55 deg [2] and the insufficient temporal resolution of spacecraft in LEO means there is currently no source of continuous imagery for polar-regions obtained with a data refresh rate of less than 15 minutes, as is typically available elsewhere for meteorological observations

Safely dissolvable and healable active packaging films based on alginate and pectin

Extensive usage of long-lasting petroleum based plastics for short-lived application such as packaging has raised concerns regarding their role in environmental pollution. In this research, we have developed active, healable, and safely dissolvable alginate-pectin based biocomposites that have potential applications in food packaging. The morphological study revealed the rough surface of these biocomposite films. Tensile properties indicated that the fabricated samples have mechanical properties in the range of commercially available packaging films while possessing excellent healing effciency. Biocomposite films exhibited higher hydrophobicity properties compared to neat alginate films. Thermal analysis indicated that crosslinked biocomposite samples possess higher thermal stability in temperatures below 120 °C, while antibacterial analysis against E. coli and S. aureus revealed the antibacterial properties of the prepared samples against different bacteria. The fabricated biodegradable multi-functional biocomposite films possess various imperative properties, making them ideal for utilization as packaging material

Naturally Occurring Halloysite Nanotubes as Light Scatterers for Stable Random Lasing Applications

Naturally occurring halloysite nanotubes (HNTs) have attracted significant scientific interest due to their multifunctional behavior and biocompatibility. However, the application of HNTs in photonics is still unexplored. Here, natural HNTs with different lengths and diameters have been employed as passive scatterers for the generation of random laser (RL) emission from rhodamine B (RhB) in a colloidal phase. Upon pumping at 532 nm, mixed HNT-RhB disordered colloidal systems are shown to yield orange RL emission with a linewidth as small as & SIM;4 nm. Moreover, a statistical analysis of shot-to-shot correlations among RL modes reveals an obvious photonic paramagnetic to spin-glass transition with increasing pump energy, which is a unique statistical fingerprint of RL. Interestingly, besides acting as scatterers, the HNTs are also found to improve the photostability of RhB molecules. Indeed, HNTs help to better dissipate the excess energy deposited in the gain medium, thus protecting the dye from photodegradation and facilitating the achievement of RL. The results contribute to the theoretical understanding and technical development of low-cost RL devices based on widely available sources in view of multiple prospective applications in photonics

Biochar enhances root development and aloin content of mature leaves in containerized Aloe arborescens Mill

The leaves of the medicinal plant Aloe arborescens Mill. Asphodelaceae) contain significant amounts of bioactive metabolites, including aloin (a mixture of the two diastereoisomers, aloin A and aloin B), aloesin, isoaloeresin D, and aloenin A. The presence of these metabolites varies considerably depending on the plant’s growth conditions, including the used growing substrate. In recent years, there has been growing interest in using biochar for potted plants cultivation. However, there is currently no available information regarding the suitability of biochar for the containerized cultivation of A. arborescens. A pot experiment was conducted with the hypothesis that biochar could influence the growth and phytochemistry of A. arborescens. The growing medium was supplied with increasing proportions of biochar (1: 100% commercial substrate; 2: mixed 50%(v/v) substrate; 3: 100% conifers wood biochar). Over the course of three years, the plants were closely monitored, and several key growth parameters were measured, including plant height, stem diameter, number and weight of leaves, and the number of suckers. After the first year, the content of selected active metabolites wasassessed. This evaluation also involved a comparison of the respective levels in the leaves taken from the apical, median, and basal sections of the stem. The leaves collected from the median section of plants were found to be larger and exhibited the highest percentage of spikes, epidermis, and gel on fresh weight. As a general trend, it was observed that in plants cultivated within the highest amount of biochar, the leaves collected from the intermediate stem portion contained the highest quantity of secondary metabolites

Born too young and likely to die : Should this continue?

Peer reviewe

Generation of optimal trajectories for Earth hybrid pole sitters

A pole-sitter orbit is a closed path that is constantly above one of the Earth's poles, by means of continuous low thrust. This work proposes to hybridize solar sail propulsion and solar electric propulsion (SEP) on the same spacecraft, to enable such a pole-sitter orbit. Locally-optimal control laws are found with a semi-analytical inverse method, starting from a trajectory that satisfies the pole-sitter condition in the Sun-Earth circular restricted three-body problem. These solutions are subsequently used as first guess to find optimal orbits, using a direct method based on pseudospectral transcription. The orbital dynamics of both the pure SEP case and the hybrid case are investigated and compared. It is found that the hybrid spacecraft allows savings on propellant mass fraction. Finally, it is shown that for sufficiently long missions, a hybrid pole-sitter, based on mid-term technology, enables a consistent reduction in the launch mass for a given payload, with respect to a pure SEP spacecraft

Epidemiology and burden of Rotavirus-associated hospitalizations in Ferrara, Italy

Objective of this study was to provide data on hospitalizations for rotavirus gastroenteritis (RVGE) in Ferrara, Italy. The study was conducted analyzing the hospital discharge forms of all children admitted to the Pediatric Department of the University of Ferrara, Arcispedale Sant'Anna, from January 2001 through December 2005. The database was searched for all gastrointestinal diseases and in particular RVGE. During the period under study 3277 children, of which 2038 inf.60 months of age, were hospitalized; 247 children inf.5 years old were admitted for acute gastroenteritis and 89 (4.4% of all and 36% of gastroenteritis-related hospitalizations) had rapid screening tests positive for rotavirus. A seasonal pattern was observed for RVGE with an increase in winter and early spring. The average length of hospital stay was 5.7 days. The median cost of each hospitalized case of RVGE ranged between 1417 and 1595 Euros. The present research confirms that rotavirus gastroenteritis represents an important cause of hospitalization in children and is responsible for significant costs for the Public Health Care System. An effective vaccination program could significantly reduce the incidence of hospitalization and the associated costs

Energetics of surface melt in West Antarctica

We use reanalysis data and satellite remote sensing of cloud properties to examine how meteorological conditions alter the surface energy balance to cause surface melt that is detectable in satellite passive microwave imagery over West Antarctica. This analysis can detect each of the three primary mechanisms for inducing surface melt at a specific location: thermal blanketing involving sensible heat flux and/or longwave heating by optically thick cloud cover, all-wave radiative enhancement by optically thin cloud cover, and f&ouml;hn winds. We examine case studies over Pine Island and Thwaites glaciers, which are of interest for ice shelf and ice sheet stability, and over Siple Dome, which is more readily accessible for field work. During January 2015 over Siple Dome we identified a melt event whose origin is an all-wave radiative enhancement by optically thin clouds. During December 2011 over Pine Island and Thwaites glaciers, we identified a melt event caused mainly by thermal blanketing from optically thick clouds. Over Siple Dome, those same 2011 synoptic conditions yielded a thermal-blanketing-driven melt event that was initiated by an impulse of sensible heat flux and then prolonged by cloud longwave heating. The December 2011 synoptic conditions also generated f&ouml;hn winds at a location on the Ross Ice Shelf adjacent to the Transantarctic Mountains, and we analyze this case with additional support from automatic weather station data. In contrast, a late-summer thermal blanketing period over Pine Island and Thwaites glaciers during February 2013 showed surface melt initiated by cloud longwave heating and then prolonged by enhanced sensible heat flux. One limitation thus far with this type of analysis involves uncertainties in the cloud optical properties. Nevertheless, with improvements this type of analysis can enable quantitative prediction of atmospheric stress on the vulnerable Antarctic ice shelves in a steadily warming climate. &nbsp;</p