Revolutionary Concepts of Radiation Shielding for Human Exploration of Space

This Technical Memorandum covers revolutionary ideas for space radiation shielding that would mitigate mission costs while limiting human exposure, as studied in a workshop held at Marshall Space Flight Center at the request of NASA Headquarters. None of the revolutionary new ideas examined for the .rst time in this workshop showed clear promise. The workshop attendees felt that some previously examined concepts were de.nitely useful and should be pursued. The workshop attendees also concluded that several of the new concepts warranted further investigation to clarify their value

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 192

This bibliography lists 247 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1979

Instrumentation for Biological Research, Volume I, Sections 1 to 3 Final Report, Nov. 9, 1964 - Mar. 31, 1966

Bioinstrumentation for controlling and measuring parameters interacting with biological syste

Fabrication of nanofiber scaffolds by electrospinning and it\u27s potential for tissue engineering

Electrospinning is a fabrication process that uses an electric field to control the deposition of polymer fibers on to a target substrate. This electrospinning strategy can be used to fabricate fibrous polymer mats composed of fiber diameters ranging from several microns down to tens of nanometers. This study assesses the potential of electrospinning, as an alternative scaffold fabrication technique for tissue engineering applications. In this study, electrospinning is adapted to produce tissue-engineering scaffolds of two different size ranges composed of non-woven poly-L-lactide (PLLA) nanofibers and as a first study, the potential use of these scaffolds as tissue engineering scaffolds was assessed with the cell proliferation of Mesenchymal stem cells. Electrospun fibers were characterized for fiber diameter, porosity, pore size and its distribution. The electrospun scaffolds achieved a high surface area and porosity. Mesenchymal stem cells (MSC) were seeded on to electrospun PLLA scaffolds having two different fiber diameters. The cell-polymer constructs were cultured under static culture conditions. Cell proliferation study was performed. The results showed that MSC tend to proliferate well on nanofibers than on microfibers

Spacesuit Integrated Carbon Nanotube Dust Mitigation System For Lunar Exploration

Lunar dust proved to be troublesome during the Apollo missions. The lunar dust comprises of fine particles, with electric charges imparted by solar winds and ultraviolet radiation. As such, it adheres readily, and easily penetrates through smallest crevices into mechanisms. During Apollo missions, the powdery dust substantially degraded the performance of spacesuits by abrading suit fabric and clogging seals. Dust also degraded other critical equipment such as rovers, thermal control and optical surfaces, solar arrays, and was thus shown to be a major issue for surface operations. Even inside the lunar module, Apollo astronauts were exposed to this dust when they removed their dust coated spacesuits. This historical evidence from the Apollo missions has compelled NASA to identify dust mitigation as a critical path. This important environmental challenge must be overcome prior to sending humans back to the lunar surface and potentially to other surfaces such as Mars and asteroids with dusty environments. Several concepts were successfully investigated by the international research community for preventing deposition of lunar dust on rigid surfaces (ex: solar cells, thermal radiators). However, applying these technologies for flexible surfaces and specifically to spacesuits has remained an open challenge, due to the complexity of the suit design, geometry, and dynamics. The research presented in this dissertation brings original contribution through the development and demonstration of the SPacesuit Integrated Carbon nanotube Dust Ejection/Removal (SPIcDER) system to protect spacesuits and other flexible surfaces from lunar dust. SPIcDER leverages the Electrodynamic Dust Shield (EDS) concept developed at NASA for use on solar cells. For the SPIcDER research, the EDS concept is customized for application on spacesuits and flexible surfaces utilizing novel materials and specialized design techniques. Furthermore, the performance of the active SPIcDER system is enhanced by integrating a passive technique based on Work Function Matching coating. SPIcDER aims for a self-cleaning spacesuit that can repel lunar dust. The SPIcDER research encompassed numerous demonstrations on coupons made of spacesuit outerlayer fabric, to validate the feasibility of the concept, and provide evidence that the SPIcDER system is capable of repelling over 85% of lunar dust simulant comprising of particles in the range of 10 m-75m, in ambient and vacuum conditions. Furthermore, the research presented in this dissertation proves the scalability of the SPIcDER technology on a full scale functional prototype of a spacesuit knee joint-section, and demonstrates its scaled functionality and performance using lunar dust simulant. It also comprises detailed numerical simulation and parametric analysis in ANSYS Maxwell and MATLAB for optimizing the integration of the SPIcDER system into the spacesuit outerlayer. The research concludes with analysis and experimental results on design, manufacturability, operational performance, practicality of application and astronaut safety. The research aims primarily towards spacesuit dust contamination. The SPIcDER technology developed in this research is however versatile, that can be optimized to a wide range of flexible surfaces for space and terrain applications-such as exploration missions to asteroids, Mars and dust-prone applications on Earth

Polarização elétrica de biomateriais baseados em hidroxiapatite, como filmes em substratos metálicos, para aumento da bioatividade

Foi desenvolvido de raiz um sistema experimental que permite carregar amostras através de uma descarga controlável num tríodo de corona. O sistema desenvolvido permite produzir uma descarga de polaridade positiva ou negativa, aplicar o método de carregamento com corrente de carga constante, seguir em tempo real o aumento do potencial de superfície da amostra, controlar a temperatura de descarga até 200 ºC e possui uma atmosfera reprodutível de baixa humidade. O sistema foi desenvolvido com o intuito de carregar com uma descarga de corona negativa revestimentos bioactivos de hidroxiapatite depositados por dois processos: spray de plasma e CoBlast, este último um processo relativamente recente. Foram estudados os seguintes parâmetros de processo do CoBlast: razão mássica entre abrasivo e dopante, distância de ejeção e pressão de ejeção. Mostrou-se que razões mássicas de 50/50 e distâncias inferiores a 30 mm são vantajosas. O método de carregamento com corrente de carga constante não é possível ser aplicado nos revestimentos produzidos por CoBlast, pois estes são caracterizados como tendo regiões onde substrato metálico está directamente exposto à descarga. Os revestimentos produzidos por spray de plasma, com uma espessura média de 70 m, foram carregados negativamente a 200 ºC com sucesso, atingindo potenciais de superfície na gama dos - 1400-1800 V, traduzindo-se em campos eléctricos nas amostras praticamente impossíveis de serem atingidos por polarização convencional de contacto. O controlo de corrente de carga é melhor para mais baixas correntes de carga. Ensaios e medidas complementares feitas em pastilhas de hidroxiapatite revelaram densidades de carga armazenada na gama dos 10-5 - 10-4 C/cm2, bem como uma estabilidade temporal da carga armazenada muito promissora. Os testes biológicos in vitro revelaram uma maior proliferação osteoblástica nos revestimentos carregados comparativamente com os revestimentos de controlo não carregados, indicando também um estágio mais avançado de formação de nova hidroxiapatite em solução simuladora de fluido corporal.A corona triode experimental system was developed “from scratch”. The developed system is able to produce a negative or positive discharge, to apply the constant charging current method, to follow in real-time the surface potential buildup of the sample, to control the discharge temperature up to 200 ºC and a low humidity, reproducible atmosphere is maintained in all the charging experiments. The system was developed in order to charge with a negative corona discharge hydroxyapatite bioactive coatings produced by two processes: plasma spray and CoBlast, the former being a relatively recent process. The following CoBlast process parameters were studied: the weight ratio between the abrasive and dopant, the blasting distance and the blasting process. It was shown that a weight ratio of 50/50 and distances lower than 30 mm are preferable. The constant charging current method cannot be applied in the coatings produced through the CoBlast process, because they are characterized by having regions where the metallic substrate is directly exposed to the discharge. The coatings produced through the plasma spray process, with an average thickness of 70 m, were successively charged at 200 ºC, reaching surface potentials in the - 1400-1800 V range, translating in electric fields across the samples which are practically impossible of being reached through conventional contact polarization. The charging current controllability is better for lower charging current values. Complementary experiments performed in hydroxyapatite coatings revealed stored charge densities in the 10-5 – 10-4 C/cm2 range, as well as a very promising temporal stability of the stored charge. The in vitro biological tests revealed an increased osteoblastic proliferation in the charged coatings compared to non-charged control coatings, also indicating a more advanced stage of new hydroxyapatite development in a simulated body fluid solution.Programa Doutoral em Físic

Evaluation Of Polyvinyl Alcohol (PVA) For Electrospinning Utility In The Blood Vessel Mimic (BVM) Lab

Electrospinning has provided the opportunity to create extracellular matrix (ECM) mimicking scaffolds for the development of tissue-engineered constructs. Within Professor Kristen Cardinal’s Blood Vessel Mimic (BVM) Lab, at Cal Poly, there exists a constant demand for innovation and the expansion of polymer types and electrospinning capabilities for its BVM model. Along these lines, the BVM Lab has recently acquired two new electrospinning systems: the Spinbox, a commercially graded electrospinning system, and the Learn-By-Doing system, which was part of a recently completed thesis conducted by Jason Provol. Additionally, recently published literature has demonstrated polyvinyl alcohol (PVA) as a viable option for creating electrospun scaffolds in the nanometer range. These findings prompt interest in investigating this polymer type due to its potential for producing extremely thin fiber diameters. Therefore, the overall objective of this thesis was to enhance the electrospinning capabilities of the BVM Lab through the utilization of the water-soluble polymer, PVA and to comprehensively compare the three available electrospinning systems within the BVM Lab, for novel tissue engineering or classroom applications. The work performed in this thesis was structured around three main Aims. The first Aim of this thesis was to demonstrate the feasibility of using PVA to create flatsheet scaffolds using the Spinbox system. To achieve this, different PVA types with varying degrees of hydrolysis (DH) and molecular weight (MW) were spun to determine the most suitable PVA formulation. These experiments revealed that PVA with low DH and ultra-high MW was the most suitable for electrospinning. Subsequently, a formal Design of Experiments (DOE) was conducted to determine an effective parameter combination for Spinbox flatsheets. The DOE yielded a parameter combination with a voltage of 27 kV, a flow rate of 0.50 ml/hr, a gap distance of 17 cm, and a weight percentage of 10%. The selection of a PVA formulation with appropriate parameters in Aim 1 established the groundwork for accomplishing the objectives of Aim 2. Aim 2 sought to extend PVA’s electrospinning utility to other collector geometries across all three of the BVM lab’s electrospinning systems, while also comparing the usability, safety, and adjustability of each system relative to one another. This was the first time all 3 systems were directly compared. The results from Aim 2 demonstrated the reproducibility of tubular scaffolds on both the Custom and Spinbox systems, featuring nanoscale fibrous scaffolds, as well as on the LBD system with flatsheets. Furthermore, a qualitative comparison of the systems indicated that the Spinbox exhibited the highest degree of adjustability and safety among the electrospinners, albeit with the lowest relative degree of usability. Conversely, the LBD system demonstrated the highest usability or intuitiveness, while also being the most hazardous and least adjustable of the systems. The Custom system ranked in the middle for all three metrics. Finally, the successful creation of tubular PVA scaffolds led to Aim 3 of this thesis, which focused on evaluating the potential of PVA scaffolds in a bioreactor environment for research applications and devising an accessible classroom PVA protocol for teaching applications. To accomplish this final aim, the scaffolds produced in Aim 2 were characterized and evaluated based on their solubility in cell-media. Additionally, methods for enhancing water-resistance through methanol cross-linking were explored and assessed. The results indicated that cross-linking PVA with methanol could enhance water resistance, but additional treatment would be necessary for PVA to serve as a standalone vascular scaffold in BVMs. However, a PVA Lab protocol was successfully developed to facilitate classroom education, providing a tangible and immediately impactful outcome of this thesis

Biomedical Sensing and Imaging

This book mainly deals with recent advances in biomedical sensing and imaging. More recently, wearable/smart biosensors and devices, which facilitate diagnostics in a non-clinical setting, have become a hot topic. Combined with machine learning and artificial intelligence, they could revolutionize the biomedical diagnostic field. The aim of this book is to provide a research forum in biomedical sensing and imaging and extend the scientific frontier of this very important and significant biomedical endeavor

The origin of extracellular fields and currents — EEG, ECoG, LFP and spikes

Neuronal activity in the brain gives rise to transmembrane currents that can be measured in the extracellular medium. Although the major contributor of the extracellular signal is the synaptic transmembrane current, other sources — including Na+ and Ca2+ spikes, ionic fluxes through voltage- and ligand-gated channels, and intrinsic membrane oscillations — can substantially shape the extracellular field. High-density recordings of field activity in animals and subdural grid recordings in humans, combined with recently developed data processing tools and computational modelling, can provide insight into the cooperative behaviour of neurons, their average synaptic input and their spiking output, and can increase our understanding of how these processes contribute to the extracellular signal

Pixel neurochip characterization

In this work a probe built for in-vivo neuronal recording is presented and analysed. Advantages that this design provide for extracellular potential measurements are discussed along with standard electro-physiological methods. Starting from simulations and physical characterizations the conditions necessary to properly operate the sensor are deduced. Issues and limitations will be discussed and addressed together with possible investigation methods. The final part consist in a discussion on high-k dielectric materials that can be included in the fabrication process of the chip. Impedance properties and parameters of interest from a biological standpoint are also extracted