The Study and Application of Carbon Nanotube Film Heaters for Space Applications

The purpose of this research was to examine the feasibility of using Carbon Nanotube (CNT) sheets as thin film heaters for space applications. The ability to maintain the temperature of space components has a direct impact on a space vehicle\u27s operation and longevity. Currently etched foil heaters are used to heat satellite batteries. Battery heaters are the focus of this research. However, as this study will show, they have limitations and are susceptible to failure. CNT sheets have many beneficial properties and show potential in replacing the etched foil design. In this study test specimens were created by forming laminate test articles comprised of CNT sheets and an adhesive Kapton® substrate material. These test articles were subjected to a series of tests both in atmosphere and in vacuum. Comparative tests were done on etched foil heaters and specimens made from a new polyimide material from Dupont™. As a secondary study, the effects of CNT grain orientation on heat generation capability was included. It was found that while the CNT articles were not as power efficient as the etched foil design, in the configurations tested, they offered a much higher maximum temperature, a faster response time (how fast the specimens heated up), and mitigated the potential for total heater failure. With respect to the grain orientation study, it was found that using commercial off the shelf (COTS) CNT sheets resulted in no significant change in thermal properties for specimens of the size used in these tests. In conclusion, CNT thin film heaters proved to be a viable alternative to current battery heater technology

In situ measurement of bovine serum albumin interaction with gold nanospheres

Here we present in situ observations of adsorption of bovine serum albumin (BSA) on citratestabilized gold nanospheres. We implemented scattering correlation spectroscopy as a tool to quantify changes in the nanoparticle Brownian motion resulting from BSA adsorption onto the nanoparticle surface. Protein binding was observed as an increase in the nanoparticle hydrodynamic radius. Our results indicate the formation of a protein monolayer at similar albumin concentrations as those found in human blood. Additionally, by monitoring the frequency and intensity of individual scattering events caused by single gold nanoparticles passing the observation volume, we found that BSA did not induce colloidal aggregation, a relevant result from the toxicological viewpoint. Moreover, to elucidate the thermodynamics of the gold nanoparticle-BSA association, we measured an adsorption isotherm which was best described by an anti-cooperative binding model. The number of binding sites based on this model was consistent with a BSA monolayer in its native state. In contrast, experiments using poly-ethylene glycol capped gold nanoparticles revealed no evidence for adsorption of BSA

Application of isothermal titration calorimetry in evaluation of protein–nanoparticle interactions

Nanoparticles (NPs) offer a number of advantages over small organic molecules for controlling protein behaviour inside the cell. Protein binding to the surface of NPs depends on their surface characteristics, composition and method of preparation (Mandal et al. in J Hazard Mater 248–249:238–245, 2013). It is important to understand the binding affinities, stoichiometries and thermodynamical parameters of NP–protein interactions in order to see which interaction will have toxic and hazardous consequences and thus to prevent it. On the other side, because proteins are on the brink of stability, they may experience interactions with some types of NPs that are strong enough to cause denaturation or significantly change their conformations with concomitant loss of their biological function. Structural changes in the protein may cause exposure of new antigenic sites, “cryptic” peptide epitopes, potentially triggering an immune response which can promote autoimmune disease (Treuel et al. in ACS Nano 8(1):503–513, 2014). Mechanistic details of protein structural changes at NP surface have still remained elusive. Understanding the formation and persistence of the protein corona is critical issue; however, there are no many analytical methods which could provide detailed information about the NP–protein interaction characteristics and about protein structural changes caused by interactions with nanoparticles. The article reviews recent studies in NP–protein interactions research and application of isothermal titration calorimetry (ITC) in this research. The study of protein structural changes upon adsorption on nanoparticle surface and application of ITC in these studies is emphasized. The data illustrate that ITC is a versatile tool for evaluation of interactions between NPs and proteins. When coupled with other analytical methods, it is important analytical tool for monitoring conformational changes in proteins

Observation of Charge-Dependent Azimuthal Correlations in p-Pb Collisions and Its Implication for the Search for the Chiral Magnetic Effect

Peer reviewe

Psychometric properties of the German Stroke and Aphasia Quality of Life Scale 39 generic version

Background: The international expert consensus core outcome set for post-stroke aphasia recommends the Stroke and Aphasia Quality of Life Scale - 39/generic (SAQOL-39g) for assessing patient-reported health-related quality of life. Cultural adaptations of the SAQOL-39g are mandatory in stroke rehabilitation.Aim: We adapted the original English SAQOL-39g into German and evaluated its psychometric quality.Design: Evaluation of a self-report scale embedded in a prospective multicenter parallel group randomized waitlist-controlled trial on the effectiveness of intensive speech and language therapy.Setting: Nineteen in- and outpatient aphasia rehabilitation centers in Germany.Population: People with chronic post-stroke aphasia (N.=156) of all types and severity levels.Methods: We followed applicable guidelines for cross-cultural test adaptations and psychometric evaluations. Psychometric analyses are based on the assessment before three weeks of intensive speech and language therapy (acceptability, internal consistency, validity; N.=156), on the assessments before and after three weeks of waiting in the control group (test-retest reliability; N.=78), and on the assessments before and after three weeks of intensive speech and language therapy (responsiveness; N.=156).Results: The German SAQOL-39g was feasible across all aphasia severity grades (no missing data; no floor/ceiling effects). Internal consistency was excellent (Cronbach's α=0.90); test-retest reliability was moderate-to-good (intraclass-correlations: ICC=0.73 for single/0.85 for average measures). Both exploratory factor analyses and multidimensional scaling of proximity data/graphical network analysis supported the 3-dimensional structure (domains: physical, psychosocial, communication) of the English original version. Convergent (|r|=0.29 to 0.48) and discriminative (|r|=0.03 to 0.07) validities were acceptable. Responsiveness to intervention-induced change showed a small-to-medium treatment effect (group difference after intervention compared to waiting-list control: Cohen's d=0.34).Conclusions: The German SAQOL-39g is a reliable, valid and change-sensitive patient-reported outcome measure to assess the physical, communication and psychosocial quality of life in chronic post-stroke aphasia, with comparable psychometric properties and factorial structure to the original English version.Clinical rehabilitation impact: The German SAQOL-39g is an easy-to-administer and -score patient-reported scale that can be used in rehabilitation settings to measure health-related quality of life and support patient-centered goal setting in people with chronic post-stroke aphasia of different ages, stroke durations, severity and type of aphasia