The potential of natural, photosynthetic pigments to improve the efficiency of dye-sensitized solar cells

Gemstone Team GrenergyCurrent photovoltaic cells incorporate silicon or synthetic dyes; however, these cells are expensive and the dyes are toxic. Our product uses natural, photosynthetic pigments to sensitize an alternative design solar cell, the dye-sensitized solar cell (DSSC). Research has shown that plant pigments are suitable sensitizers for these cells, but there is presently no good rationale to determine which pigment combinations may be most effective. Our research goal was to develop and test an absorption index for pigment selection that would increase the output of DSSCs. Our results demonstrated a positive correlation between spectral absorption of the sensitizing dye and power output of the cell. Certain pigment combinations were more effective sensitizers based on combined absorption capabilities, but resolving the mechanisms of the exact relationship requires further research and likely further development of the algorithm used to choose optimal pigment combinations

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

Professional English for students of E-learning Institute in specialty of «Electrical Engineering and Electrical Power Engineering»

Пособие предназначено для студентов 3 курса ИнЭО, изучающих профессиональный курс английского языка и обучающихся по заочной классической, дистанционной и гибридной формам обучения по направлению 13.03.02 «Электроэнергетика и электротехника»

Formation of hydrothermal REE-phosphate deposits

Rare earth elements (REE) are important metals used in green and low-carbon energy and information technologies and are widely used for geological petrogenetic studies. It is becoming increasingly evident that the REE can be mobile in certain hydrothermal fluids and even form hydrothermal REE deposits. This study focuses on the formation of hydrothermal REE deposits rich in the REE-phosphates (monazite [(LREE,Y)PO4] and xenotime [(Y,HREE)PO4]). The main objective of the study was to characterise the Olserum-Djupedal REE-phosphate mineralisation in SE Sweden. Based on this, the study evaluates different sources of REE and P in hydrothermal deposits and assesses how REE and P are transported in hydrothermal fluids. To characterise the Olserum-Djupedal REE mineralisation, this study combines fieldwork, petrographical and textural analysis, major and trace element mineral chemistry of REE-bearing minerals and the main gangue phases, stable Cl isotopic and halogen analysis of fluorapatite, and fluid inclusion microthermometry and LA-ICP-MS analysis. The primary Olserum-Djupedal REE mineralisation comprises co-existing monazite-(Ce), xenotime-(Y) and fluorapatite. These occur mainly within veins dominated by biotite, magnetite, gedrite and quartz forming within metasedimentary rocks in or close to the contact aureole of a peraluminous alkali feldspar granite. The veins are also hosted by the granite within the outermost part of this granite. Primary REE-minerals formed by granitic-derived NaCl-FeCl2-KCl-CaCl2-HF-H2O fluids at high temperatures of ~600 °C at c. 1.8 Ga. Subsequently, the ore assemblages were variably modified during cooling by CaCl2-NaCl to NaCl-CaCl2 brines, and partly, CO2-rich fluids down to temperatures of ~300 °C and to at least 1.75 Ga. Hydrothermal REE deposits rich in REE-phosphates are commonly associated with alkaline magmatism, particularly in silicate-carbonatitic systems. This is because REE and P both exhibit strong chemical affinities with carbonatitic systems and the potential for mobilisation of REE and P are high. This study shows that REE deposits can also form by hydrothermal activity related to subalkaline magmatic rocks. Peraluminous granites exhibit the greatest potential to exsolve fluids carrying REE and P, which can lead to the formation of hydrothermal REE deposits rich in REE-phosphates. The general understanding on how hydrothermal REE-phosphate deposits form is that REE and P are transported in separate fluids and that the REE-phosphates form when these two fluids mix, or the REE-phosphates form when REE-bearing fluids interact with P-rich rocks. The lack of rocks pre-enriched in P in the Olserum-Djupedal district and the co-crystallisation of fluorapatite, monazite-(Ce) and xenotime-(Y), however, suggest that such scenarios not necessarily account for all occurrences of hydrothermal REE-phosphate deposits. As an alternative, REE and P can have been transported by the same fluid. This study demonstrates that the most probable conditions for co-transport of REE and P are at temperatures exceeding 400 °C and with increasing salinity of the fluids, conditions that agree well with that of the Olserum-Djupedal system. The most effective co-transport of REE and P would occur at acidic conditions by REE-Cl, REE-F or REE-SO4 complexes. Yet, co-transport of REE and P may also be feasible at neutral to alkaline conditions by REE-OH complexes. In low-temperature hydrothermal systems, the interaction of REE-bearing fluids with P-rich rocks or fluids is probably the most efficient mechanism for precipitating REE-phosphates. In high-temperature magmatic-hydrothermal systems, REE and P probably share a common origin and were transported by the same fluid. In such systems, pH changes, cooling and the destabilisation of the chief REE transporting complexes jointly contribute to the precipitation of REE-phosphates.De sällsynta jordartsmetallerna (på engelska förkortat REE; Rare Earth Elements) är en grupp grundämnen som idag har en nyckelroll i många högteknologiska applikationer inklusive s.k. grön och fossilfri energiteknik. Över tid har flera REE-mineraliseringar konstaterats ha bildats helt eller delvis av hydrotermala fluider (högtempererade vattenlösningar). Hur sådana förekomster kan bildas är ett idag högaktuellt forskningsområde. Den här studien är fokuserad på bildandet av hydrotermala REE-förekomster innehållande REE-fosfaterna monazit [(LREE,Y)PO4] och xenotim [(Y,HREE)PO4], två viktiga värdmineral för REE i jordskorpan. Studien inriktar sig främst på att karakterisera de nyupptäckta REE-mineraliseringarna i området kring Olserum-Djupedal utanför Västervik i sydöstra Sverige. Fortsättningsvis undersöks ursprunget av REE och P i dessa förekomster, hur REE och P transporteras i de hydrotermala lösningarna och vilka processer som lett fram till bildandet av monazit och xenotim från dem. Den primära mineraliseringen i Olserum-Djupedal domineras av samexisterande monazit-(Ce), xenotim-(Y) och REE-förande fluorapatit i gångar huvudsakligen bestående av biotit, magnetit, gedrit och kvarts. Gångarna förekommer i metasedimentära bergarter kring och i kontaktgården till en peraluminös alkalifältspatgranit. Gångarna uppträder även i utkanten av samma granit. Sammantaget visar resultaten att den primära REE-mineraliseringen har ett hydrotermalt ursprung och bildades för omkring 1,8 miljarder år sedan av högtempererade (ca. 600°C) fluider från den närliggande graniten. De primära associationerna omvandlades därefter under avtagande temperatur till ca. 300°C för åtminstone 1,75 miljarder år sedan. Hydrotermala mineraliseringar med REE-fosfater förknippas vanligtvis med alkalina magmatiska bergarter och karbonatiter eftersom både REE och P i regel uppvisar en stark kemisk affinitet till sådana magmor. Den här studien visar att REE-fosfatförekomster även kan bildas av hydrotermal aktivitet relaterad till magmatiska bergarter av betydligt mindre alkalin karaktär. Av dessa system så har graniter med peraluminös karaktär störst potential att avge fluider anrikade på både REE and P. Den generella uppfattningen om hur hydrotermala REE-fosfatmineraliseringar har bildats är att REE och P transporterats i separata fluider och att REE-fosfater fällts ut som en konsekvens av att dessa fluider blandats, eller att REE-fosfater bildats som ett resultat av att REE-förande fluider reagerat med fosforrika bergarter. Avsaknaden av fosforrika bergarter i området kring Olserum-Djupedal och förekomsten av samexisterande fluorapatit, monazit-(Ce) och xenotim-(Y) visar dock att sådana scenarier inte nödvändigtvis förklarar alla förekomster av hydrotermala REE-fosfatmineraliseringar. Som ett alternativ kan REE och P ha transporterats i samma fluid. De mest troliga förhållanden för samtransport av REE och P är i fluider med temperaturer som överstiger 400°C och som har höga salthalter. Vidare så gynnar låga pH samtransport av REE och P då olika metallkomplex med REE, exempelvis REE-Cl, REE-F eller REE-SO4, är väldigt stabila under dessa förhållanden. Samtransport av REE och P är också möjlig vid ett mer neutralt eller basiskt pH. I ett scenario som innefattar samtransport av REE och P så kan pH-förändringar, sänkta temperaturer och destabilisering av viktiga REE-metallkomplex i kombination bidra till utfällning av REE-fosfater. Sammanfattningsvis kan man säga att i lågtempererade hydrotermala system har REE-fosfaterna sannolikt inte bildats av fluider omfattande samtransport av REE och P, utan genom blandning av två olika fluider eller genom samverkan mellan REE-förande fluider och fosforrika bergarter. I många högtempererade magmatisk-hydrotermala system (> 400°C) så har förmodligen REE och P i REE-fosfaterna däremot haft ett gemensamt ursprung och transporterats i samma fluid

The Second Conference on Lunar Bases and Space Activities of the 21st Century, volume 2

These 92 papers comprise a peer-reviewed selection of presentations by authors from NASA, the Lunar and Planetary Institute (LPI), industry, and academia at the Second Conference on Lunar Bases and Space Activities of the 21st Century. These papers go into more technical depth than did those published from the first NASA-sponsored symposium on the topic, held in 1984. Session topics included the following: (1) design and operation of transportation systems to, in orbit around, and on the Moon; (2) lunar base site selection; (3) design, architecture, construction, and operation of lunar bases and human habitats; (4) lunar-based scientific research and experimentation in astronomy, exobiology, and lunar geology; (5) recovery and use of lunar resources; (6) environmental and human factors of and life support technology for human presence on the Moon; and (7) program management of human exploration of the Moon and space

Marshall Space Flight Center Research and Technology Report 2017

This report features over 60 technology development and scientific research efforts that collectively aim to enable new capabilities in spaceflight, expand the reach of human exploration, and reveal new knowledge about the universe in which we live. These efforts include a wide array of strategic developments: launch propulsion technologies that facilitate more reliable, routine, and cost effective access to space; in-space propulsion developments that provide new solutions to space transportation requirements; autonomous systems designed to increase our utilization of robotics to accomplish critical missions; life support technologies that target our ability to implement closed-loop environmental resource utilization; science instruments that enable terrestrial, solar, planetary and deep space observations and discovery; and manufacturing technologies that will change the way we fabricate everything from rocket engines to in situ generated fuel and consumables

Environmental Technologies to Treat Rare Earth Element Pollution

Rare earth elements (REE) have applications in various modern technologies, e.g., semiconductors, mobile phones, magnets. They are categorized as critical raw materials due to their strategic importance in economies and high risks associated with their supply chain. Therefore, more sustainable practices for efficient extraction and recovery of REE from secondary sources are being developed. This book, Environmental Technologies to Treat Rare Earth Elements Pollution: Principles and Engineering: presents the fundamentals of the (bio)geochemical cycles of rare earth elements and which imbalances in these cycles result in pollution. overviews physical, chemical and biological technologies for successful treatment of water, air, soils and sediments contaminated with different rare earth elements. explores the recovery of value-added products from waste streams laden with rare earth elements, including nanoparticles and quantum dots. This book is suited for teaching and research purposes as well as professional reference for those working on rare earth elements. In addition, the information provided in this book is helpful to scientists, researchers and practitioners in related fields, such as those working on metal/metalloid microbe interaction and sustainable green approaches for resource recovery from wastes