Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

Naturally Occurring Asbestos: the problem of quantification

L'abstract è presente nell'allegato / the abstract is in the attachmen

A review of artificial intelligence technologies in mineral identification : classification and visualization

Artificial intelligence is a branch of computer science that attempts to understand the essence of intelligence and produce a new intelligent machine capable of responding in a manner similar to human intelligence. Research in this area includes robotics, language recognition, image identification, natural language processing, and expert systems. In recent years, the availability of large datasets, the development of effective algorithms, and access to powerful computers have led to unprecedented success in artificial intelligence. This powerful tool has been used in numerous scientific and engineering fields including mineral identification. This paper summarizes the methods and techniques of artificial intelligence applied to intelligent mineral identification based on research, classifying the methods and techniques as artificial neural networks, machine learning, and deep learning. On this basis, visualization analysis is conducted for mineral identification of artificial intelligence from field development paths, research hot spots, and keywords detection, respectively. In the end, based on trend analysis and keyword analysis, we propose possible future research directions for intelligent mineral identification.The National Natural Science Foundation of China.https://www.mdpi.com/journal/jsanElectrical, Electronic and Computer Engineerin

NASA Tech Briefs, December 1989

Topics include: Electronic Components and Circuits. Electronic Systems, Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Fabrication Technology, Mathematics and Information Sciences, and Life Sciences

Rat bladder muscle regeneration induced by local delivery of an engineered insulin-like growth factor 1 in fibrin gels

Currently, both congenital abnormalities and developmental problems of the bladder in children, and other dysfunctions in adults, require reconstructive surgery. Such correction involves transplant action of native tissues (such as gastrointestinal segments, or mucosa), homologous tissues from a donor, heterologous tissues or substances, or artificial materials to act as a replacement for normal bladder tissue. However, such surgery does not entirely restore the function, as the replacement tissue is either rejected due to immune system, fibrosis, contraction or causes metabolic complications due to a mismatch in different functional parameters, such as gastrointestinal segment for absorbance versus bladder for excretion. Tissue engineering is emerging as a significant alternative potential treatment for bladder dysfunction. To achieve this goal, we have explored fibrin gels as a natural material based scaffold to seed infiltrating smooth muscle cells to mimic the ontogeny of the bladder tissue. Our interest in developing fibrin-based biomaterial technology is based on fibrin's central role in tissue binding and in the initiation of tissue repair and defence. It is well known that fibrinogen/fibrin binds to platelets as well as to different cells, growth factors, and extracellular matrix proteins, which is critical for the wound repair process. Insulin-like growth factor I (IGF1) is well known as a key regulator in carbohydrate metabolism and growth. It can promote smooth muscle cell growth. In this thesis it was also chosen due to its simple active form, namely a single chain of low molecular weight, 10kDa. A novel engineered insulin-like growth factor I (IGF1) – factor XIIIa substrate fusion protein was chosen as the bioactive macromolecule to be released from the scaffold in order to control cellular growth and differentiation. Therefore, we can achieve close to the natural biomechanical environment in the regenerated tissue. In this work, two generations of fibrin matrices for tissue engineering were developed. The first part of the work was devoted to preventing rapid diffusion of the growth factor from the matrix and to controlling its release. IGF1 was modified by inserting a factor XIIIa substrate sequence (denoted TG) based on the α2-plasmin inhibitor to cross-link into the fibrin gel during coagulation. This is so that the variant IGF1 will bind to the fibrin gel itself and will be released upon matrix degradation. In order to produce this recombinant protein TG-IGF1, IGF1 GST tag plasmid DNA was transformed into BL21 competent cells. After protein production, the recombinant TG-IGF1 protein was purified by GST affinity chromatography. The purified TG-IGF1 was confirmed via SDS-PAGE and western blot with an anti-hIGF1 antibody. The sequence was confirmed using MALDI-TOF mass spectrometry. The biological activity of TG-IGF1 was validated in vitro by receptor tyrosine phosphorylation and metabolic assay (MTT assay) with fibroblast 3T3 cells. The cell proliferation profile was similar for both TG-IGF1 and native recombinant IGF1. Although we were able to obtain relatively pure TG-IGF1 protein, the purification protocol may still require some development due to loss of protein via aggregation during protein production. Using a three-dimension in vitro model, neonatal human bladder smooth muscle cells were seeded in the fibrin gel only, in the fibrin gel either with TG-IGF1 or native recombinant IGF1 as a control. The morphology of the seeded cells was analysed using ultra-structural transmission electron microscopy after three days. Secretory vesicles had not been found in the cells without IGF1. The cells with the TG-IGF1 displayed larger and more numerous secretory vesicles than those with native recombinant IGF1, presumably due to the rapid diffusional loss of the native recombinant IGF1 from the gel. The bladder smooth muscle cell in the fibrin gel responses to either TG-IGF1 or native recombinant IGF1 at the genomic level were analyzed by qRT-PCR for extracellular matrix and adhesion molecules after 24 hours incubation. The cells in the fibrin gel only were used as control. We did not observe a difference in gene expression between the two groups. The bioactivity of TG-IGF1 was also investigated in vivo utilizing a rat bladder model. A wound was induced via resection on the rat bladder. Either the TG-IGF1 or native recombinant IGF1 containing fibrin gel was then applied to the wound site, with a second control group receiving only the fibrin gel alone. Three classic histological stainings were done using Hematoxylin & Erythrosine (HE), Masson's Trichrome (TM) and Prussian Blue (PB). It was found that TG-IGF1 greatly enhanced rat bladder muscle layer regeneration compared to native recombinant IGF1 and the control group of fibrin gel according to the histology staining and quantitative analysis of the ratio of detrusor muscle regenerated / normal detrusor muscle (0.27±0.10 for TG-IGF1 and 0.23±0.10 for native recombinant IGF1). The second part of the work was devoted to making a new generation of fibrin matrices. Fibrinogen (Fgn), a soluble plasma protein found in all vertebrates, is a covalent dimer composed of pairs of three polypeptide chains called Aα-, Bβ- and γ-chains. Fibrinogen Aα chain can be truncated to Bβ-and γ-chains while maintaining the capacity to be assembled into a secreted, detectable fibrinogen. It is feasible to produce recombinant chimeric fibrinogen in cell culture, which can then be used to incorporate growth factors into fibrin matrices as a fusion protein with fibrinogen at the genetic level. In this way, fibrin based natural material hydrogels can be formed which can bind and release signalling biomacromolecules for directed cellular growth and tissue regeneration. In order to produce this new fibrinogen recombinant protein, a novel stable cell line of Chinese Hamster Ovary cells, CHOfgn-hIGF1, needed to be developed. This was accomplished via transfection of an FGA-hIGF1 plasmid DNA into CHOβγ cells. After protein production, the recombinant chimeric fibrinogen variant hIGF1 fusion protein was purified by affinity chromatography. The successful production of these cell lines and the resultant variant IGF1 was confirmed via ELISA with fibrinogen and hIGF1 antibodies, and also by fluorescence activated cell sorting (FACS). Due to protein polymerisation in the column during purification, the protein purification step still requires additional development. Although the targeted fusion protein was successfully produced, overall protein yield was so low as to prevent further exploration. By harnessing the powerful technique of protein engineering and using the fibrinogen/fibrin hydrogels developed in our lab, we were able to demonstrate a new type of multifunctional gel capable of regenerating smooth muscle type tissue with the aim to repair bladder function. Here we were able to demonstrate the production of the variant IGF1 factor XIIIa substrate fusion protein, its biological activity in vitro, and its application in an in vivo rat model

Understanding the Variable Drivers of Toxicity for the Broad Class of Carbon Nanotubes and Nanofibers from U.S. Facilities

Pulmonary exposure to carbon nanotubes or nanofibers (CNT/F) is known to induce inflammation, toxicity, or tumorigenesis, and is a concern in the occupational setting. U. S. facility employees are at risk of inhalation exposure of multi-walled carbon nanotubes and carbon nanofibers during primary and secondary manufacturing. To date, only one MWCNT, Mitsui-7 has been classified as possibly carcinogenic to humans (Group 2B), while all other materials were subsequently categorized as unclassifiable (Group 3). This class of material has recently been listed as a high priority to the International Agency for Research on Cancer due to this significant knowledge gap. Furthermore, expressed desire to better understand the toxicity profiles of these materials has emerged from the National Institute for Occupational Safety and Health. While human research to date is limited, the use of in in vivo and in vitro model systems can be implemented for the assessment of toxicity outcomes following respiratory exposure to CNT/F. The goal of this study was to generate an accurate an effective safety profile of MWCNT and CNFs from U. S. facilities, and to adapt a multi-disciplinary approach using machine learning to identify pertinent physicochemical characteristics that act as drivers of these toxicity outcomes. This study established toxicity profiles from male C57BL6/J mice aged 8-10 weeks exposed to either 4 or 40 µg of one of nine different CNT/F via oropharyngeal aspiration as well as human epithelial BEAS-2B cells (0-24 µg/ml), differentiated THP-1 cells (0-120 µg/ml), and human fibroblasts (0-2 µg/ml) for four primary outcomes of genotoxicity, inflammation, pathology, and translocation. The nine materials used in this study had a wide range of characteristics including diameter (6-397 nm), length (0.1-50 µm), surface area (18-238 m2/g), aspect ratio (2-1396), residual metal catalyst (0.3-6.2 %), density (0.007-0.220 g/cm3), etc., to consider. Toxicity profiles were generated regarding these four primary toxicity outcomes, and both supervised and unsupervised machine learning was used to identify the key drivers of these adverse health effects. While some physicochemical characteristics were determined to be key drivers of specific toxicity outcomes, different characteristics were essential when considering other toxicity endpoints. No single characteristic could be used as a toxicity predictor, therefore, multifactorial processes, or combination of characteristics, were necessary for an accurate and effective prediction model for responses. The study identified physicochemical drivers of CNT/F toxicity using an integrated approach, combining experimental evidence with computational modeling, with potential for broad application. This study provides necessary information for the consideration of the potential human health effects that can result from CNT/F exposure. The safety profiles and identified drivers of toxicity may be useful for future predictive risk assessment studies and translational studies as well as contributing to safety-by-design for future material designs

Development of an integrated opto-electric biosensor to dynamically examine cytometric proliferation and cytotoxicity

My doctoral research has focused on the development of microscale optical techniques for examining micro/bio fluidics. Preliminary work measured the velocity field in a microchannel, by optical slicing, using Confocal Laser Scanning Microscopy (CLSM). Next, Optical Serial Sectioning Microscopy (OSSM) was applied to examine thermometry by detecting the free Brownian motion of nano-particles suspended in mediums at different temperatures. An extension of this work used objective-based Total Internal Reflection Fluorescence Microscopy (TIRFM) to examine the hindered Brownian motion of nano-particles that were very close to a solid surface (within 1 mm). An optically transparent and electrically conductive Indium Tin Oxide (ITO) biosensor and an integrated dynamic live cell imaging system were developed to dynamically examine changes in cell coverage area, cell morphology, cell-substrate adhesion, and cell-cell interaction. To our knowledge this is the first sensor capable of conducting simultaneous optical and electrical measurements. This system consists of an incubator, which keeps cells viable by providing the necessary environmental conditions (37 °C temperature and 5 % CO2), and multiple microscopy techniques, including multispectrum Interference Reflection Microscopy (MS-IRM), TIRFM, Epi-fluorescence Microscopy, Phase Contrast Microscopy (PCM), and Differential Interference Contrast Microscopy (DICM). Along with investigations of cytometric proliferation including cellular barrier functions, in vitro cytotoxicity experiments were also conducted to examine the effect of a drug (cytochalasin D, a toxic agent) on cellular motility and cellular morphology. These cytotoxicity results give us a fundamental understanding of the cellular processes induced by the drug, which will be invaluable in the search for methods of preventing metastases. In this research, MS-IRM is used to examine the focal contacts and the gap morphology between cells and substrates, DICM is used to examine the coverage area of cells, and impedance measurements are used to correlate these two parameters. Advances in the understanding of vascular bio-transport in endothelial cells will have an impact on many aspects of cell biology, tissue engineering, and pharmacology. Particularly important will be the ability to test the popular hypothesis that the cell barrier function is regulated by specific cytoskeleton elements controlling intercellular and extracellular coupling

NASA Tech Briefs, March 1989

This issue's special features cover the NASA inventor of the year, and the other nominees for the year. Other Topics include: Electronic Components & and Circuits. Electronic Systems, Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Fabrication Technology, Mathematics and Information Sciences, and Life Science