Quartz Crystal Microbalances for Space: Design and Testing of a 3D Printed Quasi-Kinematic Support

Outgassing or thruster’s generated contaminants are critical for optical surfaces and optical payloads because scientific measurements and, in general, the performances can be degraded or jeopardized by uncontrolled contamination. This is a well-known issue in space technology that is demonstrated by the growing usage of quartz crystal microbalances as a solution for measuring material outgassing properties data and characterizing the on-orbit contamination environment. Operation in space requires compatibility with critical requirements, especially the mechanical and thermal environments to be faced throughout the mission. This work provides the design of a holding structure based on 3D printing technology conceived to meet the environmental characteristics of space application, and in particular, to face harsh mechanical and thermal environments. A kinematic mounting has been conceived to grant compatibility with a large temperature range, and it has been designed by finite element methods to overcome loading during the launch phases and cope with a temperature working range down to cryogenic temperatures. Qualification in such environments has been performed on a mockup by testing a prototype of the holding assembly between −110 °C and 110 °C and allowing verification of the mechanical resistance and stability of the electrical contacts for the embedded heater and sensor in that temperature range. Moreover, mechanical testing in a random environment characterized by an RMS acceleration level of 500 m/s2 and excitation frequency from 20 to 2000 Hz was successfully performed. The testing activity allowed for validation of the proposed design and opened the road to the possible implementation of the proposed design for future flight opportunities, also onboard micro or nanosatellites. Moreover, exploiting the manufacturing technology, the proposed design can implement an easy assembling and mounting of the holding system. At the same time, 3D printing provides a cost-effective solution even for small series production for ground applications, like monitoring the contaminants in thermo-vacuum chambers or clean rooms, or depositions chambers

Deterioration of vestibular motion perception: a risk factor for postural instability and falls in elderly with type 2 diabetes

Aims: To assess whether impaired vestibular perception of self-motion is a risk factor for unsteadiness and falls in elderly patients with type 2 diabetes (T2D). Materials and methods: 113 participants (65–75 years old) with T2D underwent tests of roll and pitch discrimination, postural stability (Berg Balance Scale, Modified Romberg Test, and quantitative posturography), clinical examination and blood chemistry analyses. Falls 1-year after enrolment were self-reported. We performed cluster analysis based on the values of the vestibular motion thresholds, and logistic stepwise regression to compare the clinical-biochemical parameters between clusters. Results: We identified two clusters (VC1 n = 65 and VC2 n = 48 participants). VC2 had significantly (p < 0.001) higher (poorer) thresholds than VC1: mean pitch threshold 1.62°/s (95% CI 1.48–1.78) in VC2 and 0.91°/s (95% CI 0.84–0.98) in VC1, mean roll threshold 1.34°/s (95% CI 1.21–1.48) in VC2 and 0.69°/s (95% CI 0.64–0.74) in VC1. Diabetes duration was significantly (p = 0.024) longer in VC2 (11.96 years, 95% CI 9.23–14.68) than in VC1 (8.37 years, 95% CI 6.85–9.88). Glycaemic control was significantly (p = 0.014) poorer in VC2 (mean HbA1c 6.74%, 95% CI 6.47–7.06) than in VC1 (mean HbA1c 6.34%, 95% CI 6.16–6.53). VC2 had a significantly higher incidence of postural instability than VC1, with a higher risk of failing the Modified Romberg Test C4 (RR = 1.57, χ2 = 5.33, p = 0.021), reporting falls during follow-up (RR = 11.48, χ2 = 9.40, p = 0.002), and greater postural sway in the medio-lateral direction (p < 0.025). Conclusions: Assessing vestibular motion thresholds identifies individuals with T2D at risk of postural instability due to altered motion perception and guides vestibular rehabilitation

A ternary PEDOT-TiO2-reduced graphene oxide nanocomposite for supercapacitor applications

A ternary composite of PEDOT was prepared with TiO2 via emulsion polymerization method adjusting various weight ratios of TiO2 to PEDOT and synthesized rGO was then blended with this composite. The FTIR, UV–Vis and XRD analysis displayed characteristic features of PEDOT and TiO2. The morphology of the nano-hybrid structure was additionally investigated by SEM analysis. Pore size and surface area analysis of particles were characterized by BET method. The electrochemical analysis showed that the specific capacitance (Csp) for PEDOT-TiO2-15-rGO was 18.9 F.cm-2 at 0.1 mA g-1 current density

Rapid sedimentation, overpressure, fluid flow and slope instability at the Gulf of Mexico continental margin

Integrated Ocean Drilling Programme (IODP) Expedition 308 studied overpressure and fluid flow on the Gulf of Mexico continental slope. The scientific program examined how sedimentation, overpressure, fluid flow, and deformation are coupled in a passive continental margin setting. The expedition investigated the model of how extremely rapid deposition of finegrained mud leads to rapid build-up of pore pressure in excess of hydrostatic (overpressure), underconsolidation and continental slope instability. Expedition 308 tested this model by examining how physical properties, pressure, temperature, and pore fluid compositions vary within low-permeability mudstones that overlie a permeable, overpressured aquifer. Three sites were drilled in the Ursa Basin off the Mississippi Delta, using the research drillship R/V JOIDES RESOLUTION (Fig. 1). In the Ursa Basin rapid, late Pleistocene sedimentation was known to be present. Drilling documented severe overpressure in the mudstones overlying the aquifer. The most important achievement of IODP Expedition 308 is to have successfully recorded in situ formation pressure and temperature in an overpressured basin. This is the first time that a coherent data set of such measurements has been obtained

Exacerbation of pemphigus after influenza vaccination

Pemphigus is a rare autoimmune disease characterized by flaccid blisters and erosions on skin and mucous epithelia. A critical event in its pathogenesis is production of antidesmoglein antibodies, which mediate the loss of intercellular adhesion in epithelia, leading to blister formation. Multiple environmental factors (ultraviolet radiation, trauma, drugs, infective agents) have been suggested as possible triggers of pemphigus. Occasionally, the disease has been reported to follow viral and bacterial vaccination. We describe a patient who experienced exacerbation of pemphigus shortly after administration of the influenza vaccination on two separate occasions. We review the literature, suggest possible explanations for a causal relationship, and discuss the administration of vaccination to these patients. © 2008 The Author(s)

Finite element modelling of thermoelastic behavior for high-temperature quartz crystal microbalance

This work focuses on the study of high-temperature microbalances to be used in space, exploring the feasibility of reaching relatively high working temperatures, i.e up to 300°C. The studied microbalance, based on a quartz crystal sensor, is equipped with an integrated heater on the crystal surface that provides localized heating on the sensor, thus achieving the operative temperature more efficiently than by using external heaters. A finite element model of the crystal assembly was developed and tuned by thermal testing in a vacuum chamber aimed to identify equivalent thermal resistance and at the same time, verify the mechanical resistance of the crystal assembly when heated at high temperatures. The tuned model allowed evaluation of the thermo-elastic stress state on the crystal, showing that the achieved operative condition is critical for the quartz crystal mechanical resistance