Letteratura scientifica selezionata sul tema "Baritō"
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Articoli di riviste sul tema "Baritō"
1
Mu’Alim, Muhammad, e Yohannes Sardjono. "MODELING THE RADIATION SHIELDING OF BORON NEUTRON CAPTURE THERAPY BASED ON 2.4 MEV D-D NEUTRON GENERATOR FACILITY". JURNAL TEKNOLOGI REAKTOR NUKLIR TRI DASA MEGA 20, n. 1 (25 gennaio 2018): 13. http://dx.doi.org/10.17146/tdm.2018.20.1.3633.
Testo completoAbstract (sommario):
Radiation shield at Boron Neutron Capture Therapy (BNCT) facility based on D-D Neutron Generator 2.4 MeV has been modified with pre-designed beam shaping assembly (BSA). Modeling includes the material and thickness used in the radiation shield. This radiation shield is expected to protect workers from radiation doses rate that is not exceed 20 mSv·year-1 of dose limit values. The selected materials are barite, paraffin, polyethylene and lead. Calculations were performed using the MCNPX program with tally F4 to determine the dose rate coming out of the radiation shield not exceeding the radiation dose rate of 10 μSv·hr-1. Design 3 was chosen as the recommended model of the four models that have been made. The 3rd shield design uses a 100 cm thickness of barite concrete as primamary layer to surrounding 100 cm x 100 cm x 166.4 cm room, and a 40 cm borated polyethylene surrounding the barite concrete material. Then 10 cm barite concrete and 10 cm of borated polyethylene are added to reduce the primary radiation straight from the BSA after leaving the main layer. The largest dose rate was 4.58 μSv·h-1 on cell 227 and average radiation dose rate 0.65 μSv·hr-1. The dose rates are lower than the lethal dose that is allowed by BAPETEN for radiation worker lethal dose.Keywords: Radiation shield, tally, radiation dose rate, BSA, BNCT PEMODELAN PERISAI RADIASI PADA FASILITAS BORON NEUTRON CAPTURE THERAPY BERBASIS GENERATOR NEUTRON D-D 2,4 MeV. Telah dimodelkan perisai radiasi pada fasilitas Boron Neutron Capture Therapy (BNCT) berbasis reaksi D-D pada Neutron Generator 2,4 MeV dengan Beam Shaping Assembly (BSA) yang telah didesain sebelumnya. Pemodelan ini dilakukan untuk memperoleh suatu desain perisai radiasi untuk fasilitas BNCT berbasis generator neutron 2,4 MeV. Pemodelan dilakukan dengan cara memvariasikan bahan dan ketebalan perisasi radiasi. Bahan yang dipilih adalah beton barit, parafin, polietilen terborasi dan timbal. Perhitungan dilakukan menggunakan program MCNPX dengan tally F4 untuk menentukan laju dosis yang keluar dari perisai radiasi. Desain periasi radiasi dinyatakan optimal jika radiasi yang dihasilkan diluar perisai radiasi tidak melebihi Nilai Batas Dosis (NBD) yang telah ditentukan oleh BAPETEN. Hasilnya, diperoleh suatu desain perisai radiasi menggunakan lapisan utama beton barit setebal 100 cm yang mengelilingi ruangan 100 cm x 100 cm x 166,4 cm dan polietilen terborasi 40 cm yang mengelilingi bahan beton barit. Kemudian ditambahkan beton barit 10 cm dan polietilen terborasi 10 cm untuk mengurangi radiasi primer yang lurus dari BSA setelah keluar dari lapisan utama. Laju dosis terbesar adalah 4,58 μSv·jam-1 pada sel 227 dan laju dosis rata-rata yang dihasilkan adalah sebesar 0,65 µSv·jam-1. Nilai laju dosis tersebut masih dibawah ambang batas NBD yang diperbolehkan oleh BAPETEN untuk pekerja radiasi.Kata kunci: Perisai radiasi, tally, laju dosis radiasi, BSA, BNCT
2
Dera, Santy. "Pengaruh pH Larutan Terhadap Nukleasi dan Pertumbuhan Kristal Barium Sulfat Didalam Pipa Beraliran Laminar: Pengamatan Kristal Menggunakan SEM-EDX dan XRD". Gorontalo Journal of Infrastructure and Science Engineering 1, n. 2 (10 ottobre 2018): 37. http://dx.doi.org/10.32662/gojise.v1i2.490.
Testo completoAbstract (sommario):
Kerak barium sulfat merupakan kasus yang sangat umum terjadi di dalam industry minyak dan gas bumi. Adanya kerak ini mempengaruhi produksi minyak dan gas bumi, sehingga menimbulkan masalah teknis yaitu dapat menghambat laju alir, sehingga tekanan pada pipa akan semakin tinggi dan menyebabkan pipa akan pecah dan rusak. Hasil penelitian ini menyajikan tentang pengendapan kristal barit dibawah pengaruh nilai pH (6,8,10) larutan, konsentrasi Ba2+ (2500ppm, 3000ppm, 3500ppm) dan konsentrasi aditif asam lauric (5,10,20 ppm) dengan suhu konstan 300C dan laju alir 30ml/menit. Dalam kegiatan penelitian ini percobaan pengerakan BaSO4 di dalam pipa uji dilakukan dengan mereaksikan BaCL2.2H2O dan Na2SO4. Larutan dialirkan pada pipa beraliran laminar. Adapun pipa uji berisi lima kupon terbuat dari baja tahan karat (stainless steel). Hasil penelitian menunjukkan bahwa Penambahan zat aditif asam laurat dan meningkatnya nilai pH memperpanjang waktu induksi sehingga semakin lama terbentuknya inti kristal. Hal itu di akibatkan karena pH larutan mampu meningkatkan protonasi gugus asam karboksilat dari aditif sehingga mampu menghambat laju pertmbuhan kristal. Analisa SEM menunjukkan bahwa morfologi kristal BaSO4 berbentuk seperti bunga yang mengindikasikan bahwa bentuk kristal ini merupakan ciri khas kristal barit. Hasil analisis EDX menunjukkan bahwa elemen utama yang terbentuk pada sample adalah Ba, S, dan O. Sementara hasil analisis XRD memastikan bahwa kristal barium sulfat (barite), ini membuktikan kerak yang terbentuk adalah kristal barite sebagai kerak padat.
3
YALÇIN, Cihan, e Yusuf URAS. "DADAĞLI (KAHRAMANMARAŞ) BÖLGESİNDE KARBONATLI KAYAÇLAR İLE İLİŞKİLİ DAMAR TİPİ Pb-Zn CEVHERLEŞMESİNİN MİKROTERMOMETRİK ÖZELLİKLERİ". Kahramanmaraş Sütçü İmam Üniversitesi Mühendislik Bilimleri Dergisi 25, Özel Sayı (13 dicembre 2022): 36–45. http://dx.doi.org/10.17780/ksujes.1160292.
Testo completoAbstract (sommario):
Kahramanmaraş ili jeolojik yapısı sebebiyle farklı kökenli kayaçları bir arada bünyesinde barındırır. Kuzeyde Toros Orojenik Kuşağı, güneyde ise Arap levhasına ait birimler gözlenir. Dadağlı bölgesi de Arap levhasına ait kenar kıvrım kuşağında yer alır. Bu bölgenin temelinde Seydişehir formasyonuna ait birimler yüzlek verir. Bu temel üzerine ise Mesozoyik yaşlı karbonatlı kayaçlar açısal uyumsuzlukla gelmektedir. Yavuzeli bazaltı ise tüm birimleri kesmektedir. Dadağlı kuzeyindeki Mesozoyik yaşlı karbonatlı kayaçlarda damar tipi baritli kurşun-çinko cevherleşmesi bulunur. Galenit, sfalerit, pirit, serüzit, smitzonit, götit ve gang olarak da barit ve kuvars parajenezi oluşturur. Jeokimyasal analizlerde PbO maksimum %60’a ve Zn değerleri ise 1200 ppm’e kadar ulaşmaktadır. Cevher oluşturan çözeltinin kökeni hakkında bilgiler elde etmek için parajenezde yer alan barit ve kuvarsdan sıvı kapanımı ölçümleri yapılmıştır. İki fazlı olan (sıvı ve gaz) kapanımlar da yapılan ölçümlere göre ötektik sıcaklık (Te) değerleri kuvars mineralinde -22,90 ile -21,10 oC, barit mineralinde ise -20,90 ile -19,50 oC arasındadır. Son buz ergime sıcaklıkları (Tmice) değerleri ise kuvars mineralinde -9,50 ile -4,30 oC arasında barit mineralinde ise -6,50 ile -4,20 oC arasındadır. % NaCl tuzluluk eşdeğerleri kuvars mineralinde 6,88-13,40 arasında, barit mineralinde ise 6,74-9,86 arasındadır. Homojenleşme sıcaklıkları (Th, oC) ise her iki mineralde 255,30-310,20 oC arasında olup ortalama 288,15 oC’dir. Kapanımların basınç değerlerine bakıldığında hem kuvars hem de barit mineralinde benzer değerler elde edilmiş olup ortalama Ph 92,85 bar’dır. Yoğunluk değerlerine bakıldığında ise kuvarsa ait kapanımların barite ait kapanımlara göre nispten daha yoğun olduğu belirlenmiştir. Homojenleşme sıcaklığı-tuzluluk diyagramlarında kapanımlar epitermal alanlarda dağılım göstermektedir. Ötektik sıcaklık değerleri ve sıcaklığın düşmesi ile artan tuzluluk durumu, çözeltinin H2O-NaCl sisteminde olan hidrotermal bir sistemi veya seyreltilmiş formasyonu suyunu işaret etmektedir.
4
Budi, Gogot Setyo, Hurijanto Koentjoro, Joshua Wijaya e Evan Filbert Sikomena. "The attenuation coefficient of barite concrete subjected to gamma-ray radiation". MATEC Web of Conferences 258 (2019): 05030. http://dx.doi.org/10.1051/matecconf/201925805030.
Testo completoAbstract (sommario):
Barite is a non-metallic mineral, which composed of Barium Sulfate (BaSO4), has specific gravity about 4.5. It can be used for high density concrete as a shielding against gamma-ray. This paper presents the use of barite as concrete aggregates to block gamma-ray radiation. Two concrete grades fc’25 and fc’35 were prepared. The effect of barite to the attenuation coefficient of samples was studied by replacing coarse aggregate with barite and replacing both coarse and fine aggregates with barite. The results show that the protection ability of the concrete using barite aggregates subjected to gamma-ray is better than those of concrete using barite as coarse aggregate and the normal one. The attenuation coefficient of concrete fc’25 with barite as aggregates and concrete with barite as coarse aggregate is 0.294 cm-1 and 0.230 cm-1, respectively; The attenuation coefficient of concrete fc’35 with barite as aggregates and concrete with barite as coarse aggregate is 0.304 cm-1 and 0.271 cm-1, respectively; While the attenuation coefficient of normal concrete fc’ 25 and fc’35 is 0.205 cm-1 and 0.225 cm-1, respectively. The average density of normal concrete fc’ 25 and fc’35 was 2252 kg/m3 and 2323 kg/m3, 3004 kg/m3 and 3064 kg/m3 for concrete with barite as coarse aggregate, and 3461 kN/m3 and 3464 kg/m3 for concrete using barite for its aggregates.
5
Rajabi, Abdorrahman, Pouria Mahmoodi, Pura Alfonso, Carles Canet, Colin Andrew, Saeideh Azhdari, Somaye Rezaei et al. "Barite Replacement as a Key Factor in the Genesis of Sediment-Hosted Zn-Pb±Ba and Barite-Sulfide Deposits: Ore Fluids and Isotope (S and Sr) Signatures from Sediment-Hosted Zn-Pb±Ba Deposits of Iran". Minerals 14, n. 7 (28 giugno 2024): 671. http://dx.doi.org/10.3390/min14070671.
Testo completoAbstract (sommario):
Iran hosts more than 350 Precambrian to Cenozoic sediment-hosted Zn-Pb±Ba and barite-sulfide deposits, including shale-hosted massive sulfide (SHMS, also called SEDEX) and Irish-type and Mississippi Valley-type (MVT) mineralization, and barite is a common mineral in these deposits. In the SHMS deposits, barite is typically found as fine-grained disseminations in thin laminae. In these deposits, the sulfide laminae often occur as diagenetic replacements and as bands containing authigenic and diagenetic barite and pyrite framboids. In the Irish-type Zn-Pb-Ba and stratabound barite-sulfide deposits, barite exhibits various textures, including fine-grained disseminated barite, banded zebra textures, veins, and massive barite lenses. In some of the giant Irish-type deposits, as well as in the stratabound barite-sulfide mineralization, the main stratabound sulfide ore is developed within a barite envelope and is characterized by the replacement of barite and pyrite by chalcopyrite, galena, and sphalerite. In the MVT deposits, the formation of barite is often related to dolomitization, and sulfide mineralization involves the replacement of the dolomitized carbonate rocks, as well as associated barite. Fluid inclusion studies on the Irish-type deposits indicate that the temperatures and salinities of the sulfide-forming fluids are higher compared to those of the barite-forming fluids. Fluid inclusion analyses of coarse-grained barites from Irish and MVT deposits reveal their hydrothermal origin. The δ3⁴S values of sulfide minerals (pyrite, sphalerite, and galena) in Irish-type deposits exhibit a broad range of low values (mostly −28 to +5‰), primarily revealing a process of bacterial sulfate reduction (BSR). However, the textures (replacement, colloform, and banded) and more positive sulfur isotope values (+1 to +36‰) in the SHMS Zn-Pb deposits suggest that bacterial sulfate reduction (BSR) plays a less significant role. We suggest that thermochemical sulfate reduction (TSR) connected to the direct replacement of barite plays a more relevant role in providing sulfur for the sulfide mineralization in the SHMS, barite-sulfide, and MVT deposits. Based on the textual evidence, sulfur isotopic data, and fluid inclusion studies, barite has been identified as a key controller for the subsequent Zn-Pb mineralization by providing a suitable host and significant sulfur contribution in the sediment-hosted Zn-Pb and stratabound barite-sulfide deposits. This implies that diagenetic barite might be a precursor to all types of sediment-hosted Zn-Pb mineralization.
6
Reza, Fachrul. "KEBERADAAN ULA PUCUAK (Trimeresurus barati) PADA BEBERAPA DAERAH DI SUMATERA BARAT". Bioconcetta 1, n. 2 (ottobre 2015): 87–93. http://dx.doi.org/10.22202/bc.2015.v1i2.1509.
Testo completo
7
Guembou Shouop, Cebastien Joel, Sang-In Bak, Eric Jilbert Nguelem Mekontso, Maurice Ndontchueng Moyo e David Strivay. "Barite concrete-based cement composites for 252Cf spontaneous neutron and 60Co/192Ir shielding based on Monte Carlo computation". Materials Research Express 9, n. 4 (1 aprile 2022): 045502. http://dx.doi.org/10.1088/2053-1591/ac5e8d.
Testo completoAbstract (sommario):
Abstract Barite concrete composite materials have been investigated for 252Cf spontaneous neutron and 60Co/192Ir gamma sources’ shielding using Monte Carlo computational method. The Particle and Heavy Ion Transport code System (PHITS) was used to compute the shielding properties of three different materials (barite concrete, barite cement, and barite aggregate) used as structural walls in fixed neutron & gamma industrial radiography for Non-Destructive Testing applications. The obtained results displayed good properties of barite concrete in shielding spontaneous neutrons emitted from the 252Cf source, as the effective dose drops about 108 times in only 140 cm wall thickness, and it was found to be about 10 times more effective than other materials investigated. In addition, the investigated gamma shielding properties of the barite concrete showed a relatively smaller wall thickness compared to the ordinary concrete. The decision-making process based on the ALARA principle of dose limitation showed that the use of barite concrete in such facilities is more effective than the use of barite cement and barite aggregate, for both gamma and neutron radiography shielding design. To achieve an average value of 1 μSv/h, the obtained result shows that 80 cm of Barite concrete is needed, while 125 and 130 cm of barite cement and barite aggregate are needed, respectively to shield the Co-60 source. Meanwhile, 50 cm of wall made of barite concrete is sufficient to cut down the effective dose rate to 1 μSv/h (for 50 Ci and 55 cm for 150 Ci 192Ir), which is an appropriate design for the public area adjacent to the industrial radiographic facility. It was therefore concluded from the obtained data that barite concrete is the most effective shielding material for radioactive sources (60Co, 192Ir, and 252Cf) used in radiographic applications.
8
Bonny, Sandy M., e Brian Jones. "Barite (BaSO4) biomineralization at Flybye Springs, a cold sulphur spring system in Canada's Northwest Territories". Canadian Journal of Earth Sciences 44, n. 6 (29 giugno 2007): 835–56. http://dx.doi.org/10.1139/e06-126.
Testo completoAbstract (sommario):
The Flybye Springs, Northwest Territories, consist of 10 active vents and numerous small seeps that discharge sulphide- and barium-rich spring waters at an average temperature 8.5 °C. Oxidation of sulphide to sulphate drives precipitation of stellate and platy barite microcrystals in the proximal flow paths. Downstream, and in vent- and tributary-fed ponds, barite is precipitated among streamer and mat forming colonies of sulphur-tolerant microbes, including Thiothrix, Beggiatoa, Thioploca, Chromatium, Oscillatoria, fungi (dominantly Penicillium), and unicellular sulphate reducing bacteria. These microbes mediate barite saturation by adjusting redox gradients and via passive adsorption of barium ions to cell surfaces and extracellular polymeric substances. Passive biomineralization produces barite laminae in floating microbial mats, nanometric coatings, and micrometric encrustations around microbial cells and filaments, and local permineralization of Thiothrix, Beggiatoa, and Oscillatoria outer cell walls. Intracellular barium enrichment and (or) metabolic sulphur oxidation may be important to "active biomineralization" that produces nanometric barite globules on the tips of fungal hyphae, barite-filled cell cavities in Beggiatoa and Thiothrix, and baritized sulphur globules. Degradation of biomineralized cells generates detrital "microfossils," including barite tunnels, layered cylinders, solid cylindrical grains and chains of barite beads. The diversity of inorganic and biomineralized barite in the Flybye Springs flow path highlights the influence of ambient chemistry, microbial metabolism, and cellular structure on barite solubility and on the taphonomy of microfossils preserved in barite.
9
Wang, Chunyao, Li Zhou, Shuai Zhang, Li Wang, Chunwan Wei, Wenlei Song, Liping Xu e Wenge Zhou. "Morphology of Barite Synthesized by In-Situ Mixing of Na2SO4 and BaCl2 Solutions at 200 °C". Crystals 11, n. 8 (16 agosto 2021): 962. http://dx.doi.org/10.3390/cryst11080962.
Testo completoAbstract (sommario):
Barite is an abundant sulfate mineral in nature. Especially, the variety of morphologies of barite is often driven by the mixing of Ba-bearing hydrothermal fluid and sulfate-bearing seawater around hydrothermal chimneys. In order to better understand the factors affecting the morphology and precipitation mechanism(s) of barite in seafloor hydrothermal systems, we synthesized barite by a new method of in-situ mixing of BaCl2 and Na2SO4 solutions at 200 °C while varying Ba concentrations and ratios of Ba2+/SO42−, and at room temperature for comparison. The results show that barite synthesized by in-situ mixing of BaCl2 and Na2SO4 solutions at 200 °C forms a variety of morphologies, including rod-shaped, granular, plate-shaped, dendritic, X-shaped, and T-shaped morphologies, while room temperature barites display relatively simple, granular, or leaf-like morphologies. Thus, temperature affects barite morphology. Moreover, dendritic barite crystals only occurred at conditions where Ba2+ is in excess of SO42− at the experimental concentrations. The dendritic morphology of barite may be an important typomorphic feature of barite formed in high-temperature fluids directly mixing with excess Ba2+ relative to SO42−.
10
Khubchandani, Lachman M., e Priya Hosali. "Grassroots English in a Communication Paradigm". Language Problems and Language Planning 23, n. 3 (31 dicembre 1999): 251–72. http://dx.doi.org/10.1075/lplp.23.3.04khu.
Testo completoAbstract (sommario):
ZUSAMMENFASSUNG "Grassroots English " im Kommunikationsparadigma Der Aufsatz behandelt den kommunikativen Zugang im mehrsprachigen Zusammenhang. Er analysiert Daten aus dem in Indien gesprochenen Englisch in Bezug auf den Sprecher/Hörer, die Funktion, den Kontext und andere relevante Faktoren, die die Sprache im alltaglichen Leben bestimmen. In der postkolonialen Ära hat der Gebrauch dieses "Grassroots English" unter denjenigen, die sich in einer mehrsprachigen städtischen Umgebung spontan grundlegende Bestandteile der Sprache aneignen, in bemerkenswerter Weise zugenommen. Dieser Sprachgebrauch wird im allgemeinen nicht auf forma-lem Wege durch Unterricht erlernt. Diese Situation macht die Anpassungs-prozesse an die kontext- und funktionsspezifische Realität sichtbar. Anstatt über normative Eigenschaften des indischen Englisch auf einer Skala "einheimischer" und "nicht-einheimischer" englischer Sprachen zu theoreti-sieren, zeigt diese Studie die Komplementaritåt zwischen "Grassroots English" und anderen Sprachen Indiens, und die Entstehung dieser Variante als eine der notwendigen Kontaktsprachen im vielsprachigen Indien. RESUMO Humnivela angla en komunika paradigmo La referajo enfokusigas la komunikan aliron en plurlingvaj medioj kaj analizas donitajojn el la barata angla vidalvide al la parolanto/aüskultanto, la tasko, la kunteksto, kaj aliaj perantaj faktoroj, kiuj estras la paroladon en la ciutaga vivo. En la postkolonia epoko, okazis rimarkinda kresko en la uzo de la humnivela angla lingvo inter la spontanaj akirantoj de iuj elementaj eroj de la lingvo en urba, plurlingva medio. Tian lingvouzon oni generale ne lernas formale pere de la eduko. Tiu ci situacio montras procezojn de adaptigo al la realo specife formita de la kuntekstoj kaj la taskoj. Anstataŭ teoriumi pri la normaj trajtoj de la barata angla sur ia plurcentra globa deklivo-gamo da denaskaj kaj nedenaskaj anglaj lingvoj, tiu ci studo okupas sin identigi la komplementecon inter la humnivela angla kaj aliaj lingvoj en Barato, kaj la aperon de tiu ĉi varianto kiel unu el la vivgravaj kontakto-lingvoj en la plurisma Barato.
Tesi sul tema "Baritō"
1
Janasi, Suzilene Real [UNESP]. "Ferrita de bário: preparação de fases dopadas com cobalto, titânio e estanho". Universidade Estadual Paulista (UNESP), 1997. http://hdl.handle.net/11449/102592.
Testo completoAbstract (sommario):
Made available in DSpace on 2014-06-11T19:32:11Z (GMT). No. of bitstreams: 0
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janasi_sr_dr_araiq.pdf: 2566763 bytes, checksum: e10173459cbf62287b0478669d7c6ed0 (MD5)A substituição parcial de íons Fe3+ por pares de íons (Co2+-Ti4+ ou Co2+-Sn4+) na ferrita de bário hexagonal (BaFe12O19) leva a uma substancial diminuição no campo coercitivo (Hc) com uma pequena mudança na magnetização de saturação (Ms), permitindo seu uso em gravação magnética e magneto-óptica de alta densidade. Os diferentes métodos de preparação de ferritas de bário resultam em produtos com propriedades distintas. Neste trabalho, preparou-se BaFe12-2xCoxTixO19 e BaFe12-2xCoxSnxO19 (0,25 £ x £ 1) por coprecipitação, utilizando cloretos dos metais precursores e solução de KOH/K2CO3 como precipitante. Após a secagem, o produto obtido foi calcinado a 950oC por 3h, lavado e seco. Os difratogramas de raios X indicaram a formação da ferrita de bário. As micrografias eletrônicas de varredura mostraram que os pós obtidos apresentam-se na forma de plaquetas hexagonais de 1 a 2mm. As curvas de magnetização das ferritas de bário dopadas mostraram que o campo coercitivo e a remanência diminuem em função do aumento da razão de substituição x. A curva de magnetização da amostra dopada com Co-Ti, com x = 1 é característica de uma ferrita mole, com Hc = 13,5 kA.m-1 (0,17 kOe), Ms = 46,1 emu.g-1 e Mr = 11,0 emu.g-1. Para a amostra dopada com Co-Sn a diminuição de Mr não é significante. Estes resultados mostraram que as propriedades magnéticas das ferritas de bário dopadas obtidas por coprecipitação foram melhoradas, em relação aos dados da literatura para ferrita de bário pura ou dopada.
The partial substitution of Fe3+ ions with pairs of ions (Co2+-Ti4+ or Co2+-Sn4+) in hexagonal barium ferrite (BaFe12O19) leads to a substantial reduction on coercivity (Hc) with only a low change in saturation magnetization (Ms), allowing its use in high density magnetic and magneto-optical recording. Different preparative methods result in barium ferrites with distinguished properties. In this work, BaFe12-2xCoxTixO19 and BaFe12-2xCoxSnxO19 (0.25 £ x £ 1) were prepared by the coprecipitation method using chloride salt precursors and KOH/K2CO3 solution. After drying, the powder was calcinated at 950oC by 3 h, washed and dried. The X ray diffraction patterns indicated the barium ferrite phase formation. The scanning electron micrographs showed that the particles are hexagonal platelike with diameter size ranging from 1 to 2 mm. The magnetization curves of substituted barium ferrites showed that the values of Hc and Mr decrease with the increase of the substitution ratio x. The magnetization curve profile for Co-Ti substituted sample with x =1 is characteristic of a soft ferrite with Hc = 13.5kA.m-1 (0.17 kOe), Ms = 46.1 emu.g-1 and Mr = 11.0 emu.g-1. These results indicated that the magnetic properties of substituted barium ferrites obtained by coprecipitation were improved when compared with the literature data for pure and substituted barium ferrite.
2
Liu, Fanmao. "Photoresponse of ferroelectric BaTiO3 thin films". Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/458535.
Testo completoAbstract (sommario):
BaTiO3 es un material de óxido ferroeléctrico sin plomo. BaTiO3 películas delgadas han sido ampliamente estudiados para aplicaciones de memoria debido a su efecto de memoria de carga resultante de su naturaleza ferroeléctrica. Hoy en día, la comunidad científica ha renovado su interés en BaTiO3, ya que posee características que son interesantes para áreas de rápido desarrollo como la fotovoltaica, la detección fotoeléctrica y la fotocatálisis. El objetivo principal de la presente tesis es estudiar los efectos fotoeléctricos de las películas delgadas BaTiO3 y dar luz sobre los mecanismos relevantes que las controlan.
Los materiales ferroeléctricos muestran campos eléctricos internos intrínsecos, inevitables y exclusivos: campo eléctrico de impresión (Eimp) y campo eléctrico de despolarización (Edep). Así se pueden obtener distintos efectos fotoeléctricos debido a Eimp y Edep. En la presente tesis hemos estudiado en detalle el papel de Eimp y Edep en los efectos fotoeléctricos de películas BaTiO3. En particular, se muestra que se puede usar una configuración de medición apropiada para revelar y aislar su contribución. Como resultado, pueden obtenerse diferentes foto respuestas transitorias y constantes según se desee. De igual modo, se analiza su contribución a la dinámica de conmutación ferroeléctrica. La foto respuesta transitorio tiene su origen en el cribado de la carga superficial (fotograbado). Para modular su magnitud se ha realizado una caracterización detallada. Se concluye que la polarización de las fotos se rige por la presencia de agua adsorbida en la superficie, lo que permite su control. Sin embargo, se ha encontrado que la eficiencia fotoeléctrica está limitada por la baja generación de portadores por la luz, por lo que el efecto de O sustituido por N en la red BaTiO3, lo que debería dar lugar a un estrechamiento de banda, mejorando así la eficiencia fotoeléctrica , ha sido estudiado. Curiosamente, se encuentra que los tratamientos de amoníaco son eficientes para mejorar las respuestas fotoeléctricas, sin tener ninguna evidencia clara de la sustitución de N.BaTiO3 is a lead-free ferroelectric oxide material. BaTiO3 thin films have been widely studied for memory applications due to its charge memory effect resulting from its ferroelectric nature. Nowadays, the scientific community has renewed its interest on BaTiO3, because it holds characteristics that is interesting for rapidly developing areas such as photovoltaics, photoelectric sensing and photocatalysis. The main goal of the present thesis is to study the photoelectric effects on BaTiO3 thin films and to give light on the relevant mechanisms that control them. Ferroelectric materials show intrinsic, unavoidable and exclusive internal electric fields: imprint electric field (Eimp) and depolarization electric field (Edep). Thus distinct photoelectric effects can be obtained due to Eimp and Edep. In the present thesis we have studied in detail the role of Eimp and Edep on photoelectric effects of BaTiO3 films. In particular, it is shown that appropriate measurement configuration can be used to disclose and isolate their contribution. As a result, different transient and constant photoresponses can be obtained as wish. By the same token, their contribution to the ferroelectric switching dynamics are also analyzed. The transient photoresponse finds its origin on the screening of surface charge (photoscreening). In order to modulate its magnitude detailed characterization has been performed. It is concluded that the polarization photoscreening is governed by the presence of water adsorbed at the surface, allowing it to be controlled. However, the photoelectric efficiency has been found to be limited by the low generation of carriers by light, that is the reason why the effect of O substituted by N in BaTiO3 lattice, which should result in band-gap narrowing, hence improving the photoelectric efficiency, has been studied. Interestingly, it is found that ammonia treatments are efficient to improve photoelectric responses, without having any clear evidence of N substitution.
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ALMEIDA, JUNIOR Airton Tavares De. "Caracterização da barita e do vidro cristal como atenuadores na blindagem das radiações X e Gama". Universidade Federal de Pernambuco, 2005. https://repositorio.ufpe.br/handle/123456789/9904.
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Previous issue date: 2005Com objetivo de determinar as características de atenuação do minério sulfato de bário (BaSO4) e do vidro cristal utilizados como blindagem contra as radiações ionizantes X e gama, em instalações radiográficas, foi realizado um estudo de atenuação com argamassa e concreto de barita, usados, respectivamente, no revestimento de paredes e em blocos; e com o vidro cristal usado em biombos e janelas. Para isso, foram analisadas 10 placas de argamassa de barita, 3 placas de concreto de barita, com área média útil de 900 cm2 e espessura média de 1 a 5 cm, e 3 placas de vidro cristal, com área útil de 323 cm2, com espessuras de 1, 2 e 4 cm. As amostras foram irradiadas com raios-X, com potenciais de 60, 80,110 e 150 quilovolts, e raios gama do 60Co. As respostas de atenuação (mGy/mAmin) e (mGy/h) ambos a 1 metro, em função da espessura, resultaram na obtenção das curvas de atenuação e de transmissão. Além disso, foram determinadas as espessuras equivalentes das camadas semi e deciredutoras, tanto para o vidro cristal, como para a argamassa e o concreto de barita
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Gondim, Priscylla Cinthia Alves. "Desenvolvimento de bloco de veda??o com barita na composi??o de partida para blindagem de radia??o X". Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12744.
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Previous issue date: 2009-08-21Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
This work main objective is to study the use of bricks in barium X-rays rooms in order to contribute to the optimization of shielding rooms diagnosis. The work was based on experimental measurements of X-ray attenuation (40 to 150 kV), using ceramic seal bearing the incorporation of barium sulfat (BaSO4). Different formulations were studied in three different firing temperatures and evaluated for incorporation in the ceramic body. The composition of 20% of barite processed at a temperature of 950 ? C showed better physical and mechanical properties, is considered the most suitable for the purpose of this work. Were produced bricks sealing composition formulated based on that presented the best technological features. These blocks were tested physically as a building material and wall protective barrier. Properties such as visual, deviation from the square, face flatness, water absorption and compressive strength were evaluated for all the blocks produced. The behavior of this material as attenuator for X-rays was investigated by experimental results which take into account mortar manufacturers barium through the different strains and compared with the reference material (Pb). The simulation results indicated that the ceramic block barium shows excellent properties of attenuation equivalence lead taking into account the energy used in diagnostic X-ray
Este trabalho tem por finalidade principal estudar a utiliza??o de blocos cer?micos baritados em salas de radia??o X, visando contribuir para a otimiza??o da blindagem de salas de diagn?stico. O trabalho foi baseado em medidas experimentais de atenua??o da radia??o X (40 a 150 kV), empregando material cer?mico de veda??o contendo a incorpora??o de sulfato de b?rio (BaSO4). Diferentes formula??es foram estudadas em tr?s temperaturas de queima diferentes e avaliadas as incorpora??es na massa cer?mica. A composi??o de 20% de barita processada a temperatura de 950?C, apresentou melhores propriedades f?sicas e mec?nicas, sendo considerada a mais adequada para a proposta deste trabalho. Foram produzidos blocos cer?micos de veda??o baseados na composi??o formulada que apresentou melhores caracter?sticas tecnol?gicas. Estes blocos foram testados fisicamente como material construtivo de parede e barreira protetora. Propriedades como caracter?sticas visuais, desvio com rela??o ao esquadro, planeza das faces, absor??o de ?gua e resist?ncia ? compress?o foram avaliadas para todos os blocos produzidos. O comportamento deste material como atenuador para a radia??o X foi investigado por meio de resultados experimentais que levaram em considera??o fabricantes de argamassas baritadas atrav?s das diferentes tens?es e comparado com o material de refer?ncia (Pb). Os resultados obtidos nas simula??es indicaram que o bloco cer?mico baritado demonstra ?timas propriedades de atenua??o em equival?ncia ao chumbo levando-se em conta as energias usadas em raios X diagn?stico
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Zhong, Zhimin. "Combustion syntheses and characterization of Barium Titanate, Barium Tetratitanate and Lead substituted Barium Tetratitanate /". The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487861396027028.
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Kudelová, Barbora. "Prekonavani barier". Master's thesis, Vysoké učení technické v Brně. Fakulta architektury, 2017. http://www.nusl.cz/ntk/nusl-316300.
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Showing the barriers in the city, which inhibit a human in its movement along the landscape. Bunch of barriers at one place can signify a problem for a human to overcome. Marking these places is also showed below the prize map which illustrates from the economic point of view the problem exists at that place and the place is not that permeable as it should be. After marking the problematic spaces and their overlook in the real world there follows a choice of one place and its particular solution. Verifying the reasons why overcoming especially this place, what are the reasons for connecting it, analysing the areas on both sides, pointing out the place of connection and the way to solve the pedestrian bridge and finding the conceptual principle which is the support for the construction principle.
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Almeida, Jademir Jesus Pirapora de. "Ação da radiação de alta energia nas propriedades mecânicas de compostos elastoméricos a base de SBR carregados com barita". Universidade Presbiteriana Mackenzie, 2012. http://tede.mackenzie.br/jspui/handle/tede/1329.
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Previous issue date: 2012-03-30Universidade Presbiteriana Mackenzie
In this work were studied the action of ionizing radiation on the physical-mechanical properties in elastomeric compounds based on styrene-butadiene rubber (SBR) filled with barite, opening way for application of these composites in the protection and shield against high-energy radiation, in the form of aprons. These aprons come to substitute the elastomeric ones with lead filler in ergonomic and economically advantageous conditions. The effect of high-energy radiation was studied on SBR compounds filled with barite at 50, 75, 100, 125, and 150phr (phr = parts per hundred rubber) of barite concentrations, exposed to ionizing radiation at 0, 100, 200, 500 and 1000kGy doses. The samples were characterized by physic-mechanical tests as rheometry, tensile strength, resilience, hardness, wear resistance, oil absorption, permanent deformation under compression (compression set) and dynamic mechanical thermal analysis. The morphological characteristics were determined by scanning electron microscopy. The results showed that the radiation causes an increase in tensile strength and elongation, the tear strength and hardness, and a decrease in fluid absorção and deformation under compression.
Neste trabalho foi estudada a ação da radiação ionizante nas propriedades físico-mecânicas nos compostos elastoméricos a base de estireno-butadieno (SBR) carregados com barita, abrindo caminho para aplicação destes compostos na proteção e blindagem contra a radiação alta energia, na forma de aventais, vindo substituir os aventais a base de elastômero carregado com chumbo em condições ergonômicas e economicamente vantajosas. Foi estudado o efeito da radiação ionizante em compostos a base de SBR carregado com barita nas concentrações de 50, 75, 100, 125, e 150phr (phr = partes por cem de borracha) de barita expostos à radiação ionizante nas doses de 0, 100, 200, 500 e 1000kGy. As amostras foram caracterizadas por meio de ensaios físico-mecânicos de reometria, de resistência à tração, resiliência, dureza, resistência ao rasgo, absorção de óleo, deformação permanente sob compressão (compression set) e ensaios de análise térmica dinâmico-mecânica. As características morfológicas dos compositos foram determinadas por meio de microscopia eletrônica de varredura. Os resultados mostraram que a radiação provoca um aumento da resistência à tração, do alongamento sob tração, da resistência ao rasgamento e da dureza; e um decréscimo na absorção de fluido e na deformação sob compressão.
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FRIMAIO, AUDREW. "Desenvolvimento de um material cerâmico para utilização em proteção radiológica diagnóstica". reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11414.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Rai, Maha. "Molecular dynamics modelling of barium silicate and barium fluorozirconate glasses". Thesis, University of Kent, 2018. https://kar.kent.ac.uk/66702/.
Testo completoAbstract (sommario):
Advancement in science and technology has profoundly depended on new types of glass innovation. The glasses that were studied in this project are binary barium silicate glasses, binary barium fluorozirconate glasses, ZBLAN glasses and 〖Eu〗^(3+) doped ZBLAN glass (the ZBLAN glasses are based on binary barium fluorozirconate glass). The high atomic number of barium in the barium silicate glasses provides high mass and high electron density providing its applications for heat and X-ray shielding. The phenomena such as phase separation in the barium silicate glass will affect its properties of durability and electrical conductivity. On the other hand, ZBLAN glasses have a broad infrared optical transmission window due to the weaker bonding/interaction of F^- ions. Due to the presence of lanthanum in the composition ZBLAN glass can be easily doped with rare-earth ions such as 〖Eu〗^(3+) giving it many optical applications such as optical amplifier and fibre lasers. Hence, it's essential to study the structure of these glasses to understand their properties for applications. This thesis used the classical molecular dynamics modelling technique to study the static atomic structure of glass. Generally, fluoride glasses can be formed by totally replacing oxygen atoms in oxide glasses by fluorine atoms. The oxide silicate glasses are common glasses that follow the Zachriasen rules of glass formation but the fluorozirconate glasses do not and lack fixed structural units. The structure analysis was performed at short-range order (e.g. coordination number, bond length and bond angle), medium-range order (e.g. network connectivity) and long- range order (e.g. phase separation). The related crystals were also simulated in similar conditions to the glasses to compare their atomic structure. Normally at short-range order glass structure is similar to its related crystal but the differences between them starts from the position and number of next nearest neighbours and increases thereafter. Additionally, the new methods such as rotational invariants and grid analysis were used to scrutinise structural units and phase separation respectively. The model of barium silicate glass shows good agreement with experimental diffraction data. The typical bond length and coordination number for Ba were 2.97 Å and approximately 7 respectively. The model did not show any phase separation at low Ba content and hence for further investigation very large models of alkaline earth silicate glasses were studied to see how Ba, Ca and Mg are distributed in the glass. The grid analysis was used to see the distributions which show homogeneity for Ba and Ca and inhomogeneity for Mg cation. The structural units of fluorozirconate glasses were carefully studied as they do not follow the Zachriasen glass model. The coordination number for Zr was mixture of 7 and 8. The rotational invariant analysis shows that the structural units of ZrF_n polyhedra for coordination number 7 and 8 were similar to Augmented Triangular Prism and Biaugmented Triangular Prism respectively. However, rotational invariant values for BaF_n polyhedra tend more towards random. The large complex model of 〖Eu〗^(3+) doped ZBLAN glass was made as it is studied for optical applications. The initial analysis was to observe whether Zr and Ba has similar structural roles as in binary fluorozirconate glass system which they do. Considering the extra elements in ZBLAN glass, Al behaves like a network former and has octahedra structural units whereas La and Na behave like modifiers. In the glass Eu was uniformly distributed with predominantly coordination number of 8 and does not have well defined structural units.
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Kinsey-Nielsen, Susan Mary. "HIGH-RESOLUTION LASER SPECTROSCOPY OF BARIUM-MONOHYDROXIDE AND BARIUM-MONODEUTEROXIDE". Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/292080.
Testo completoLibri sul tema "Baritō"
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Henshūshitsu, Chikyū no Arukikata, a cura di. Baritō: Bali. Tōkyō: Daiyamondo Biggusha, 2005.
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Henshūshitsu, Chikyū no Arukikata, a cura di. Baritō: Bali. Tōkyō: Daiyamondo Biggusha, 2007.
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Toshokan, Kunitachi Ongaku Daigaku. Baritō no geinō shiryō shozō mokuroku. Tōkyō: Kunitachi Ongaku Daigaku Fuzoku Toshokan, 1991.
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Bijutsukan, Fukuoka-shi. Egakareta maryoku: 1930-nendai Baritō Batuan no kaigaten = Images of power : Balinese paintings made for Gregory Bateson and Margaret Mead. Fukuoka-shi: Fukuoka-shi Bijutsukan, 1995.
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Ober, Joyce A. Barite. [Place of publication not identified]: [U.S. Department of Interior, Bureau of Mines], 1990.
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Searls, James P. Barite. Washington, D.C: U.S. Department of the Interior, Bureau of Mines, 1993.
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Petrovich, Petrov Valentin, Delit͡s︡in I. S e Nauchnyĭ sovet po rudoobrazovanii͡u︡ (Akademii͡a︡ nauk SSSR), a cura di. Barit. Moskva: "Nauka", 1986.
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Berg, Richard B. Barite in Montana. [Butte]: Montana Bureau of Mines and Geology, Dept. of Montana College of Mineral Science and Technology, 1988.
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(Indonesia), Barito Selatan, a cura di. Barito Selatan selayang pandang. Buntok: Pemerintah Kabupaten Barito Selatan, 2000.
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A, Silva Michael. Mineral commodity report, barite. Sacramento, Calif: California Dept. of Conservation, Division of Mines and Geology, 1985.
Cerca il testo completoCapitoli di libri sul tema "Baritō"
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Rothwell, R. G. "Barite". In Minerals and Mineraloids in Marine Sediments, 42–46. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-1133-8_5.
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Gooch, Jan W. "Barite". In Encyclopedic Dictionary of Polymers, 66. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_1057.
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Heubeck, Christoph. "Barite". In Encyclopedia of Astrobiology, 250–51. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_5233.
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Heubeck, Christoph. "Barite". In Encyclopedia of Astrobiology, 328. Berlin, Heidelberg: Springer Berlin Heidelberg, 2023. http://dx.doi.org/10.1007/978-3-662-65093-6_5233.
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White, William M. "Barium". In Encyclopedia of Earth Sciences Series, 1–3. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-39193-9_79-1.
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White, William M. "Barium". In Encyclopedia of Earth Sciences Series, 91–93. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-39312-4_79.
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Pohling, Rolf. "Barium". In Chemische Reaktionen in der Wasseranalyse, 25–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-36354-2_4.
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Bourgeois, Marie M. "Barium". In Hamilton & Hardy's Industrial Toxicology, 57–62. Hoboken, New Jersey: John Wiley & Sons, Inc., 2015. http://dx.doi.org/10.1002/9781118834015.ch08.
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Gooch, Jan W. "Barium". In Encyclopedic Dictionary of Polymers, 66. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_1058.
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Brookins, Douglas G. "Barium". In Eh-pH Diagrams for Geochemistry, 168–69. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-73093-1_60.
Testo completoAtti di convegni sul tema "Baritō"
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Middleton, Julia, Adina Paytan e Tristan J. Horner. "Barium-Isotopic Signatures of Barite Diagenesis". In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.1796.
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Middleton, Julia, Adina Paytan, Mak Saito e Tristan Horner. "Barium Isotope Signatures of Barite Diagenesis". In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.5509.
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Doldersum, A., e S. Baraka-Lokmane. "Effect of Water Salinity on Barium Sulfate Formation in the Context of Gas Wells in the Dutch Sector of the North Sea". In SPE Oilfield Scale Symposium. SPE, 2024. http://dx.doi.org/10.2118/218712-ms.
Testo completoAbstract (sommario):
Abstract Operator has several gas wells which encountered barium sulfate scale. In one instance this had resulted in a complete blockage of the well and in another well not being able to perform a planned well intervention. This paper will present the investigation of the mechanism of formation of scales in combination with an overview of laboratory and field data on how to treat the barium scales. The production water of one of the wells is characterised by a very high salinity level close to saturation in combination with presence of barium, strontium, calcium, carbonate, and sulfate. The evaluation of the scaling risk has been carried out from bottomhole to wellhead with commercial software; 80 points modelling have been performed. This has helped to determine the scaling mechanisms for individual scales. Barium scale from a second well has been used to select an effective dissolvent via laboratory experiments. The evaluation of the scaling risk has been carried out with a help of a commercial software. The predicted scales are halite, barite, celestite, strontianite and calcite, while mainly barite was found in the recovered deposit. The difference between modelling results and field observation are discussed in the paper. As halite concentrations exceeded saturation levels, downhole water injection was applied in one of the wells to stay below the saturation levels, due to water evaporation caused by drawdown. However, the reduction of salinity decreases the solubility of barium sulfate which in combination with decreasing temperatures seriously increases the risk of precipitation of barium sulfate. This eventually resulted in a complete blockage of the well. For the second well, barium scale samples were tested in the laboratory to select the best dissolvent. This dissolvent had been batch injected in the upper part of the well to dissolve the scale. Collected production water at surface immediately after opening of the well, showed increased levels of barium, strontium, and sulfate. Continuous downhole injection of fresh water to compensate for evaporation losses due to drawdown should be carefully evaluated when barium sulfate scaling risk exists as the solubility decreases at lower salinity levels. One of the mitigation methods is therefore to add inhibitors to the injected water.
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Middleton, Jule, Adina Paytan e Tristan Horner. "Barium isotope fractionation during ion exchange at the barite-fluid interface: Implications for barium cycling in seawater". In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.12345.
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Wang, Xu, Salima Baraka-Lokmane e Eric Mackay. "Impact of Reservoir on Relaxation of Requirement for SRP Whilst Protecting Production - Reactive Transport Modelling for a Mature Offshore Field". In SPE Oilfield Scale Symposium. SPE, 2024. http://dx.doi.org/10.2118/218729-ms.
Testo completoAbstract (sommario):
Abstract Injection of Low Sulphate Seawater (LSSW) is widely used to reduce the barite scaling risk. LSSW may be used in addition to Produced Water Re-Injection (PWRI). LSSW injection may no longer be required when the barium concentrations in the produced water decline. This study investigates the timing and degree of relaxation of the output sulphate concentration from a Sulphate Reduction Plant (SRP) required to minimize the barite risk, accounting for the impact of PWRI. Reactive transport modelling is used to calculate brine mixing and in situ precipitation. The output of these calculations is water composition and rate profiles at the production wells, which is then used to identify the evolution of the barium sulphate scale risk in each well. Five scenarios have been considered: a one-off increase of sulphate, Full Sulphate Seawater (FSSW) injection, gradual increase of sulphate concentration over a given period, and a mixture with PWRI, where the injected brine is assumed to be 95% formation brine and 5% FSSW. Both aqueous speciation reactions and carbonate and sulphate mineral reactions are modelled. Different injection strategies are addressed, based on a geochemical transport reservoir model of a mature field. The tolerance of sulphate increase for injection brine will help in determining relaxation requirements for the SRP to reduce operational costs as well as seeking other possible late field development strategies (e.g. PWRI).
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Raja Sahar, Raja Nor Rafidah, Wan Amni W Mohamad, Ema Farima Rustam Ali Khan e Siti Aishah Mohd Hatta. "Selection of Barium Sulphate/Barite Dissolver Chemical through Establishment of Standard Laboratory Screening Protocols". In Abu Dhabi International Petroleum Exhibition & Conference. Society of Petroleum Engineers, 2019. http://dx.doi.org/10.2118/197251-ms.
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Mahmoodi, Pouria, Jan M. Peter, Abdorrahman Rajabi e Ebrahim Rastad. "Geological and textural characteristics as evidence for Irish-type mineralization in the Eastern Haft-Savaran deposit". In Irish-type Zn-Pb deposits around the world. Irish Association for Economic Geology, 2023. http://dx.doi.org/10.61153/pxze7581.
Testo completoAbstract (sommario):
The Eastern Haft-Savaran Zn-Pb-(Ba) deposit, located in the southeastern part of the Arak Mining District of the Malayer-Esfahan Metallogenic Belt, Iran, is hosted in the uppermost part of an early Cretaceous massive limestone unit that is capped by shale. The mineralization has a sheet-like geometry and is associated with intense dolomitization and silicification. The mineralization is mineralogically zoned: chalcopyrite-galena-pyrite-sphalerite-tetrahedrite occurs in the southern part of the deposit; sphalerite-galena-pyrite occurs in the central part of the deposit; and barite-galena-sphalerite-pyrite occurs in the northern part of the deposit. The thickest mineralization and most intense alteration are in the southern part of the deposit, associated with an aphyric rhyodacite flow containing minute euhedral barite crystals and Cu-bearing sulphides in vein/veinlets and disseminations, indicating this was the mineralizing fluid upflow site. Three hydrothermal mineralization stages are recognized. The first is mud lime sedimentation, framboidal pyrite, minute euhedral barite, sphalerite, galena and early dolomite. Minute euhedral barites are cut by microsparite formed by micrite recrystallization during diagenesis. First stage sphalerite and galena occur as inclusions in framboidal pyrite, and these were remobilized into inclusions in euhedral pyrite during recrystallization. The second (main) stage mineralization includes sphalerite, galena, chalcopyrite, tetrahedrite, pyrite and barite that with dolomite and quartz as gangue minerals replaced first stage mineralization and is associated with silicification and dolomitization. The third stage of mineralization comprises sphalerite and galena that is associated with dolomitization and calcitization. The occurrence of mineralization in an extensional back arc setting, massive limestone host rock, intense and pervasive host rock alteration, Fe-dolomite associated with main stage mineralization, the presence of mineralization load casts and minute euhedral barite, the remobilization of first stage of mineralization during diagenetic evolution of framboidal pyrite to euhedral pyrite, and timing of mineralization during early diagenesis of mud lime collectively indicate the Eastern Haft-Savaran deposit can be classified as an Irish-type deposit.
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Yue, Zhiwei David, Andrew Slocum, Xiaohong Lucy Tian, Linping Ke, Megan Westerman e John Hazlewood. "An Integrated Scale Protection Package for Offshore Fractured Wells Under Designed Shut-In Extension". In SPE International Conference on Oilfield Chemistry. SPE, 2021. http://dx.doi.org/10.2118/204363-ms.
Testo completoAbstract (sommario):
Abstract After fracturing, it is common practice to leave offshore wells shut-in from days to weeks for operational purposes. During the recent historic decline of demand for global crude, a trend has been witnessed to shut in even newly fractured wells under design for an extended period. The cause of these extended shut-ins can be attributed to various factors including operational logistics as well as economic factors. The shut-in extension brings some unique scaling challenges for well designs. In this paper, an integrated scale inhibitor (SI)/fracturing fluid package is presented with detailed laboratory prerequisites data to validate its efficacy for long-term scale protection during the extended shut-in. Utilizing seawater in offshore fracturing can provide significant cost savings to an operation. Unfortunately, in regions with barium-rich formations, the use of seawater brings tremendous barite scaling risk. In order to solve this challenge, the investigation focused on the selection of the most effective inhibitors for long-term barite inhibition under the simulated reservoir conditions. Along with the scale inhibitor selection, the crosslinked gel had to be carefully optimized to eliminate any potential negative interference the gel additives could impart to the performance of the inhibitor. Furthermore, the inhibitor was tested in the crosslinking system to meet optimum rheology requirements. Utilizing the broken gel containing the designed inhibitor package, barite precipitation could be prevented for months under the simulated testing conditions. Due to high levels of sulfate from seawater and the barium originating from the formation, barite scale formed immediately upon mixing of the two types of water in absence of the appropriate scale inhibitors. Solid scale products featuring slow releasing of the inhibitor ingredients was proven insufficient for this application. With extensive laboratory screening, the candidate chemistry demonstrated great brine-calcium tolerance, superior scale inhibition performance for both sulfate and carbonate scales, and the minimum interferences for the crosslinking engineering to meet necessary proppant carrying capacity. To mimic the gel-breaking process and heterogeneous bleeding from the formation water, the inhibitor was crosslinked with the gel at various loading rates (1 gpt to 10 gpt) and broken at the elevated reservoir temperature, then mixed with the different ratios of the formation water. Reliable scale inhibition performance was achieved for an extended period of time for up to six weeks. Incorporating SI into the fracturing stimulation package is a convenient method for operators to include a scale-control program into well-defined fracturing designs with minimal adjustment and also add significant cost-saving for offshore logistics and rig time (Fitzgerald, et al., 2008). The scale inhibitor product presented in this paper shows a superior solution to protect assets from scale deposition for an extended shut-in period.
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Slocum, Andrew, Zhiwei David Yue, Linping Ke, Michael Thomas, Jeremy Lacamu, Matthew Kottemann, Ken Lizak et al. "Case Studies of Novel Seawater-Based FracPac Fluid Used in DeepWater Gulf of Mexico with Barium-Rich Formation Fluids Present". In SPE Oilfield Scale Symposium. SPE, 2024. http://dx.doi.org/10.2118/218713-ms.
Testo completoAbstract (sommario):
Abstract Injecting seawater into producing formations with barium-rich formation water has been avoided for decades due to concerns of barium sulfate scale formation impairing production. The local barium-rich formations unfortunately bring immediate scaling risk due to severe tendencies to form barite when the seawater sulfate contacts barium-rich formation waters. This scaling challenge has driven the industry to utilize freshwater-based fluids for most completions operations which include fracturing and other sand control methods. As multizone completions have increased in frequency over the past decade, the logistical challenges of providing freshwater-based systems have grown greater. To overcome these challenges, a newly developed seawater-based fracturing fluid system has provided benefits over the traditional freshwater-based system. In this paper, we present case studies of four multizone completions in deepwater Gulf of Mexico which utilized a newly developed seawater-based fracturing fluid integrated with a polymeric scale inhibitor package. All four wells have barium-rich formation waters present and range in temperatures from 194 to 260°F (90 to 127°C). We share the challenges overcome in the designs and operation, field overview data, lab testing results, field deployment results, and initial production results. We also discuss the benefits seen by using seawater-based fracturing fluids for deepwater FracPac jobs to streamline logistics by eliminating the need for supply vessels and reducing cleaning wastes, CO2 emissions and freshwater use. Unlike proposals in other publications which was characterized by Hou et al. (2023), the seawater based fracturing fluid used on these treatments did not remove the seawater's sulfates by nano-filtration, forced precipitation of sulfates, electrodialysis, or any other means. Sulfate removal techniques were investigated, but currently they are not deemed practical for stimulation vessel use due to the extra equipment requirements and associated processing times.
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Ofei, Titus Ntow, Bjørnar Lund, Arild Saasen, Sigbjørn Sangesland, Harald Linga, Knud Richard Gyland e Masahiro Kawaji. "Barite Sag Measurements". In IADC/SPE International Drilling Conference and Exhibition. Society of Petroleum Engineers, 2020. http://dx.doi.org/10.2118/199567-ms.
Testo completoRapporti di organizzazioni sul tema "Baritō"
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Turner, R. J. W., e W. D. Goodfellow. Barium Carbonate Bodies Associated With the Walt [Cathy] Stratiform Barium Deposit, Selwyn Basin, Yukon: a Possible Vent Complex Associated With a Middle Devonian Sedimentary Exhalative Barite Deposit. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1990. http://dx.doi.org/10.4095/131402.
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Collings, R. K., e P. R. A. Andrews. Summary report no. 1: barite. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1988. http://dx.doi.org/10.4095/307284.
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Harris, Michael J. Barite flotation; El Cuervo Butte. New Mexico Bureau of Geology and Mineral Resources, 1988. http://dx.doi.org/10.58799/ofr-336.
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Scanlan, E. J., M. Leybourne, D. Layton-Matthews, A. Voinot e N. van Wagoner. Alkaline magmatism in the Selwyn Basin, Yukon: relationship to SEDEX mineralization. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328994.
Testo completoAbstract (sommario):
Several sedimentary exhalative (SEDEX) deposits have alkaline magmatism that is temporally and spatially associated to mineralization. This report outlines interim data from a study of potential linkages between magmatism and SEDEX mineralization in the Selwyn Basin, Yukon. This region is an ideal study site due to the close spatial and temporal relationships between SEDEX deposits and magmatism, particularly in the MacMillan Pass, where volcanic rocks have been drilled with mineralization at the Boundary deposit. Alkaline volcanic samples were analysed from the Anvil District, MacMillan Pass, Keno-Mayo and the Misty Creek Embayment in the Selwyn Basin to characterise volcanism and examine the relationship to mineralization. Textural and field relationships indicate a volatile-rich explosive eruptive volcanic system in the MacMillan Pass region in comparison to the Anvil District, which is typically effusive in nature. High proportions of calcite and ankerite in comparison to other minerals are present in the MacMillan system. Cathodoluminescence imaging reveals zoning and carbonate that displays different luminescent colours within the same sample, likely indicating multiple generations of carbonate precipitation. Barium contents are enriched in volcanic rocks throughout the Selwyn Basin, which is predominately hosted by hyalophane with rare barite and barytocalcite. Thallium is positively correlated with Ba, Rb, Cs, Mo, As, Sb and the calcite-chlorite-pyrite index and is negatively correlated with Cu. Anvil District samples display a trend towards depleted mid-ocean ridge mantle on a plot of Ce/Tl versus Th/Rb. Hydrothermal alteration has likely led to the removal of Tl from volcanic rocks in the region. Ongoing research involves: i) the analysis of Sr, Nd, Pb and Tl isotopes of volcanic samples; ii) differentiating magmatic from hydrothermal carbonate using O, C and Sr isotopes; iii) examining sources of Ba in the Selwyn Basin; iv) and constraining age relationships through U-Th-Pb geochronology.
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Stack, Andrew G. Reaction mechanisms for barite dissolution and growth. Office of Scientific and Technical Information (OSTI), luglio 2010. http://dx.doi.org/10.2172/1107642.
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Liseroudi, M. H., O. H. Ardakani, P. K. Pedersen, R. A. Stern, J M Wood e H. Sanei. Diagenetic and geochemical controls on H2S distribution in the Montney Formation, Peace River region, western Canada. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329785.
Testo completoAbstract (sommario):
The Lower Triassic Montney Formation is a major siltstone dominated unconventional tight gas play in the Western Canadian Sedimentary Basin (WCSB). In the Peace River region, the Montney Formation contains a regionally variable amount of hydrogen sulfide (H2S) in gas-producing wells with western Alberta's wells having the highest concentrations. Previous studies on the source and distribution of H2S in the Montney Formation mainly focused on variations of H2S concentration and its relationship with other hydrocarbon and non-hydrocarbon gases, sulfur isotope composition of H2S, as well as organo-sulfur compounds in the Montney Formation natural gas. None of those studies, however, focused on the role of diagenetic and geochemical processes in the formation of dissolved sulfate, one of the two major ingredients of H2S formation mechanisms, and pyrite within the Montney Formation. According to the results of this study, the Montney Formation consists of two different early and late generations of sulfate minerals (anhydrite and barite), mainly formed by the Montney Formation pore water and incursion of structurally-controlled Devonian-sourced hydrothermal sulfate-rich fluids. In addition, pyrite the dominate sulfide mineral, occurred in two distinct forms as framboidal and crystalline that formed during early to late stages of diagenesis in western Alberta (WAB) and northeast British Columbia (NEBC). The concurrence of the late-stage anhydrite and barite and various types of diagenetic pyrite with high H2S concentrations, particularly in WAB, their abundance, and spatial distribution, imply a correlation between the presence of these sulfate and sulfide species and the diagenetic evolution of sulfur in the Montney Formation. The sulfur isotope composition of anhydrite/barite, H2S, and pyrite demonstrates both microbial and thermochemical sulfate reduction (MSR and TSR) controlled the diagenetic sulfur cycle of the Montney Formation. The relationship between the delta-34S values of the present-day produced gas H2S and other sulfur-bearing species from the Montney and other neighboring formations verifies a dual native and migrated TSR-derived origin for the H2S gas with substantial contributions of in situ H2S in the Montney reservoir.
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Simandl, G. J., R. J. D'Souza, S. Paradis e J. Spence. Rare-earth element content of carbonate minerals in sediment-hosted Pb-Zn deposits, southern Canadian Rocky Mountains. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328001.
Testo completoAbstract (sommario):
Paleozoic platform carbonate rocks of the Rocky Mountains host Mississippi Valley-type (MVT), magnesite, barite, and REE-barite-fluorite deposits. Farther west, platform carbonate rocks of the Kootenay Arc host MVT and fracture-controlled replacement (FCR) deposits. This is the first systematic LA-ICP-MS study of carbonates in MVT and FCR deposits. We investigated seven MVT deposits in the Rocky Mountains, and five MVT deposits in the Kootenay Arc. None of the post-Archean Australian shale (PAAS)-normalized REE profiles show light REE (LREE) depletion and strong negative Ce anomalies characteristic of modern seawater: some profiles are nearly flat; others show depletion in LREE similar to seawater but without negative Ce anomalies; others are middle REE enriched. Carbonates with a strong positive Eu anomaly precipitated from or interacted with different fluids than carbonates with flatter profiles without a strong positive Eu anomaly. REE signatures reflect crystallization conditions of primary carbonates, and crystallization and re-equilibration conditions of carbonates with ambient fluids during diagenesis, deep burial, and/or metamorphic recrystallization. Chemical evolution of fluids along their migration path, fluid-to-rock ratio, fluid acidity, redox, and temperature also influence REE profile shape, which helps establish genetic and timing constraints on studied deposits and improves knowledge of the metallogeny of the Kootenay Arc and Rocky Mountains.
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Michael Holmes, Carolyn Nyberg, Katie Brandt, Kurt Eylands, Nathan Fiala e Grant Dunham. Subtask 1.23 - Mercury Removal from Barite the Oil Industry. Office of Scientific and Technical Information (OSTI), settembre 2008. http://dx.doi.org/10.2172/986898.
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Ballestero, Florencio. Una evaluación de la homogeneidad macroeconómica y del desarrollo de la región centroamericana. Inter-American Development Bank, dicembre 1998. http://dx.doi.org/10.18235/0011975.
Testo completoAbstract (sommario):
En relación con los países desarrollados, las ventajas comparativas de la región centroamericana se encuentran en procesos productivos de uso intensivo de mano de obra barata y recursos naturales. Sin embargo, evaluadas las ventajas regionales en un contexto mundial, también la región enfrenta la competencia de muchos otros países y regiones con el mismo tipo de ventajas comparativas respecto a los países desarrollados. La región centroamericana, por otro lado, posee, respecto a sus competidores en el mundo, una ventaja comparativa adicional para atraer procesos productivos de uso intensivo de mano de obra barata y recursos naturales, integrarse a la economía mundial y acelerar su crecimiento económico: su situación geográfica. Centroamérica es un punto de fácil acceso (o potencialmente fácil, si se cuenta con la infraestructura adecuada) a los principales mercados de Europa, Asia y las dos costas oceánicas de América del Norte.
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Macdonald, A. S. Lake Ainslie barite-fluorite veins, Cape Breton Island, Nova Scotia. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1999. http://dx.doi.org/10.4095/210474.
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