• Title/Summary/Keyword: gold-silver

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Characteristics of Gold and Silver Based Bi- and Tri-metallic SPR Chip in the Intensity Measurement Mode (반사광 측정 모드에서 금과 은을 사용한 이층 금속 칩과 삼층 금속 칩의 특성 연구)

  • Kim, Hyungjin;Kim, Chang-duk;Sohn, Young-Soo
    • Journal of Sensor Science and Technology
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    • v.25 no.2
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    • pp.143-147
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    • 2016
  • Characteristics of the conventional gold (Au) surface plasmon resonance (SPR) chip, bi-metallic(Au/silver (Ag)) SPR chip, and tri-metallic(Au/Ag/Au) SPR chip were investigated and compared in the intensity measurement mode for the enhancement of SPR image sensor reactivity. Reflectance curves of the Au, bi- and tri-metallic SPR chips were acquired in phosphate-buffered saline (PBS) solution and were compared. The line width of the reflectance curve of the bi-metallic chip was the narrowest among the three different types of the chips. Also, the tangential slope of the bi-metallic chip was steeper than those of the other chips. Various concentrations of bovine serum albumin (BSA) were utilized in the SPR experiment. As a result, among the above three chips reflectance variation value of the bi-metallic chip was the largest.

Compositional Variations of Sphalerites and Their Genetic Characteristics from Gold and/or Silver Deposits in Central Korea (한국 중부지역 금은광상산 섬아연석의 조성변화와 성인적 특성)

  • Choi, Seon-Gyu
    • Economic and Environmental Geology
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    • v.26 no.2
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    • pp.135-143
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    • 1993
  • Chemical compositions of sphalerites from 25 gold and/or silver deposits in central Korea were obtained with an electron probe microanalyzer. The FeS contents of sphalerites depend generally upon the assemblage of associated iron sulphides (pyrite and/or pyrrhotite) especially. The sphalerites coexisting with pyrrhotite show a narrow range of FeS variation, but the sphalerites associated with pyrite and/or pyrrhotite have the variable and wide range of FeS contents. The sphalerites from Au-dominant deposits, which vary considerably in each deposit, are generally characterized by high CdS content and low MnS content. On the contrary, the sphalerites from Ag-dominant and Au-Ag deposits tend to be characterized by relatively high MnS and very low CdS content. Based upon the mineralogy, fluid inclusions and stable isotope data, the Au-dominant deposits were formed under higher temperature and deeper depth than the Ag-dominant and Au-Ag deposits. The results suggest the possibility that the diverse sources and evolution of ore fluid at the time of ore deposition are responsible for the deposition of Cd and Mn components in sphalerites.

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Commodity Prices, Tax Purpose Recognition and Bitcoin Volatility: Using ARCH/GARCH Modeling

  • JALAL, Raja Nabeel-Ud-Din;SARGIACOMO, Massimo;SAHAR, Najam Us
    • The Journal of Asian Finance, Economics and Business
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    • v.7 no.11
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    • pp.251-257
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    • 2020
  • The study investigates the role of commodity prices and tax purpose recognition on bitcoin prices. Since the introduction of bitcoin in 2008, emphasis has focused on economists, policy-makers and analysts drastically increasing bitcoin's accessibility and commodity values (Dumitrescu & Firică, 2014). This study employs GARCH and EGARCH from ARCH/GARCH family on daily nature data. We measure the volatile behavior of bitcoin by employing auto-regressive conditional heteroscedasticity model with the aim to explore the relationship between major commodities and bitcoin volatility. We focus on major commodities like gold, silver, platinum, and crude oil to be regressed with bitcoin. The daily prices of commodities were retrieved from www.investing.com and bitcoin prices from www.coindesk.com for the period from 29April 2013 to 16 October 2018. Results confirmed the currency's long-term volatile behavior, which is due to its composition and market dynamics, whereas the existence of asymmetric information effect is not confirmed. Tax recognition by other countries may in future help in controlling the volatility as bitcoin is not a country-specific security. But, only silver impacts on volatility in comparison to oil prices and platinum, which is due to its similar features with gold. Eventually, bitcoin can be used for risk diversification and money making.

Microglial Contribution to Glioma Progression: an Immunohistochemical Study in Eastern India

  • Ghosh, Krishnendu;Ghosh, Samarendranath;Chatterjee, Uttara;Chaudhuri, Swapna;Ghosh, Anirban
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.6
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    • pp.2767-2773
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    • 2016
  • Human glioma, arising from glial cells of the central nervous system, accounts for almost 30%of all brain tumours, neoplasms with a poor prognosis and high mortality rates worldwide. In the present study we assessed tissue architectural modifications associated with macrophage lineage cells, controversial major immune effector cells within the brain, in human glioma tissue samples from eastern India. Ethically cleared post-operative human glioma samples from our collaborative neurosurgery unit with respective CT/MRI and patient history were collected from the Nodal Centre of Neurosciences in Kolkata, over 9 months. Along with conventional histopathology, samples were subjected to silver-gold staining and fluorescence tagged immunophenotyping for the detection of electron dense brain macrophage/microglia cells in glioma tissue, followed by immune-phenotyping of cells. With higher grades, CD11b+/Iba-1+ macrophage/microglia architecture with de-structured boundaries of glioma lesions indicated malfunction and invasive effector state. Present study documented a contribution of microglia to glioma progression in Eastern India.

Occurrence and Mineral Characteristics of Au-Ag-Cu-Bi Bearing Quartz Veins in the Estancia de la Virgen area, Guatemala (과테말라 Estancia de la Virgen 지역 금-은-동-비스무스 광화대의 산상과 광물특성)

  • Shin, Eui-Cheol;Kim, Soo-Young;Hong, Sei-Sun;Kim, In-Joon
    • Economic and Environmental Geology
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    • v.31 no.6
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    • pp.463-472
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    • 1998
  • The survey was carried out in order to delineate the occurrence of ore deposits and the mineralized characteristics in the Estancia de la Virgen area through the 1:2,000 scaled geological mapping and topographic measuring surveys. Gold-silver mineralization is in the fault block developed between the San Agustin Fault and Cabanas Fault. It is associated with ore bearing quartz veins controlled by the fault structure. The contents of Au and Ag range from traces up to 72 g/t and 180 g/t respectively. According to traversing the outcrops, the quartz veins are traced by 0.5 Km trended to north and south. In those extended part, they continue for 1,000 m intermittently. Gold-silver mineralization could be divided into three stages. In the first stage, pyrite, galena, sphalerite, and chalcopyrite were formed with the primary silver and gold associated with galena and copper sulfides respectively. In the second stage, Cu-Bi-Au-Ag bearing sulfides such as chalcocite, covellite, and linarite are formed and usually deposited on the cataclastic fractures of galena and/or chalcopyrite. In the third stage, both the carbonation of galena and sphalerite and the sulphatization of galena, took place in the surface environment. And then primary silver was carried away off and was deposited on galena and/or copper sulfides during oxidation near the water table. Low partitionings of Fe in sphalerite assist that the minerals were formed at the relatively low temperature, which is coincided with previously reported homogenization temperature of fluid inclusions.

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Ore Minerals, Fluid Inclusion and Stable Isotope Studies of the Bongsang Gold-silver Deposit, Republic of Korea (봉상 금-은광상의 광석광물, 유체포유물 및 안정동위원소 연구)

  • Yoo, Bong-Chul;Lee, Jong-Kil;Lee, Gil-Jae;Lee, Hyun-Koo
    • Economic and Environmental Geology
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    • v.41 no.1
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    • pp.1-14
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    • 2008
  • The Bongsang gold-silver deposit consists of quartz veins that fill along the fault Bone within Cretaceous andesitic lapilli tuff. Mineralization is occurred within fault-breccia zones and can be divided into two stages. Stage I which can be subdivided into early and late depositional stages is main ore mineralization and stage II is barren. Stage I began with deposition of wall-rock alteration minerals and base-metal sulfides, and was deposited by later native silver, Ag-bearing tetrahedrite, polybasite and base-metal sulfides such like pyrite, sphalerite, chalcopyrite and galena. Fluid inclusion data indicate that homogenization temperatures and salinities of stage I range from 137 to $336^{\circ}C$ and from 0.0 to 10.6 wt.% NaCl, respectively. It suggests that ore forming fluids were cooled and diluted with the mixing of meteoric water. Also, temperature and sulfur fugacity deduced mineral assemblages of late stage I are $<210^{\circ}C\;and\;<10^{-15.4}$ atm, respectively. Sulfur(3.4%o) isotope composition indicates that ore sulfur was mainly derived from a magmatic source as well as the host rocks. The calculated oxygen{2.9%o, 10.3%o(quartz: 7.9%o, 8.9%o, calcite: 2.9%o, 10.3%o)}, hydrogen(-75%o) and carbon(-7.0%o, -5.9%o) isotope compositions indicate that hydrothermal fluids may be meteoric origin with some degree of mixing of another meteoric water for paragenetic time.

A Study on Handiwork Technique of Filigree Artifacts Excavated from Neungsan-ri Temple Site in Buyeo, Korea (부여 능산리사지 출토 누금세공 유물의 제작기술 연구)

  • Lee, Sun-Myung;Kung, Seung-Nam;Kim, Yeon-Mi
    • Journal of Conservation Science
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    • v.26 no.1
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    • pp.13-24
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    • 2010
  • This study examined each handiwork method of 4 filigree artifacts from Neungsan-ri temple site in Buyeo, Korea through material characteristic and microstructure analysis. As a result, it was indicated that all of the artifacts have comparatively higher purity than 22.7K and some of filigree artifacts showed that gold is alloyed with silver at a certain ratio. Gold thread that decorates surface showed thickness of 0.2~0.8mm and displayed various forms of section. Gold granule indicated that 2 or 3 granules are adhered together and they are 0.3~0.8mm in diameter. Trace of soldering was observed from gold thread and gold granule joints on surface and it confirmed a possibility of being soldering using gold solder through componential analysis. Also, it reveals a surface decorated with pigments such as cinnabar(HgS) and black.

A Study on Comparison Experiments for Judgement to the Nondestructive Analysis of Gold Plated Silverware Remains (비파괴분석법에 의한 은제금도금유물의 판단을 위한 비교실험 연구)

  • Sim, Myung-Bo;Yu, Hei-Sun;Kim, Soo-Ki
    • Journal of Conservation Science
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    • v.27 no.1
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    • pp.41-47
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    • 2011
  • If the nondestructive analysis is carried out by using an X-ray Fluorescence Analyzer(XRF) for ingredient analysis with the target of gold plated silverware that plates gold on a silver basis, a singular point showing big difference at the value of weight percent(wt.%) according to the electron orbit of the principal ingredient can be confirmed. The present research made reproduced samples and carried out comparative analysis in order to suggest a basis that can judge whether the technique of gold plated silverware was used in case of remains uneasy to understand with eyes by using this singular point. As a result, the same result as analysis results of actual remains could be seen in specimens manufactured by a mercury amalgam plating method. However, in case of gold and silver alloy specimens, it could be confirmed that the difference according to the electron orbit of the principal ingredients is slight unlike plated specimens. The reason appearing at plated specimens seems to be generated while absorbing XRF beam at plated layers by double structure due to plating instead of single material. Accordingly, if this result appearing at nondestructive analysis is used, it was confirmed that the application of the technique of gold plated silverware can be judged without observing its section.

Stable isotope, Fluid Inclusion and Mineralogical Studies of the Samkwang Gold-Silver Deposits, Republic of Korea (삼광 금-은광상의 산출광물, 유체포유물 및 안정동위원소 연구)

  • 유봉철;이현구;최선규
    • Economic and Environmental Geology
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    • v.35 no.4
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    • pp.299-316
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    • 2002
  • The Samkwang gold-silver deposits consist of gold-silver-bearing hydrothermal massive quartz veins which filled the fractures along fault shear (NE, NW) zones within Precambrian banded or granitic gneiss of Gyeonggi massif. Ore mineralization of this deposits occurred within a single stage of quartz vein which was formed by multiple episodes of fracturing and healing. Based on vein mineralogy and paragenesis, massive quartz veins are divided into two main paragenetic stages which are separated by a major faulting event. Main ore mineralization occurred at stage I. Wall-rock alteration from this deposits occur as mainly sericitization, chloritization, silicification and minor amounts of pyritization, carbonitization, propylitization and argillitization. Ore minerals are composed mainly of arsenopyrite (29.21-32.24 As atomic %), pyrite, sphalerite (6.45-13.82 FeS mole %), chalcopyrite, galena with minor amounts of pyrrhotite, marcasite, electmm (39.98-66.82 Au atomic %) and argentite. Systematic studies of fluid inclusions in early quartz veins and microcracks indicate two contrasting physical-chemical conditions: 1). temperature (215-345$^{\circ}$C) and pressure (1296-2022 bar) event with $H_{2}O-CO_{2}-CH_{4}-NaCl$fluids (0.8-6.3 wt. %) related to the early sulfide deposition, 2). temperature (203-441$^{\circ}$C) and pressure (320 bar) event with $H2_{O}$-NaCI $\pm$ $CO_{2}$ fluids (5.7-8.8 wt. %) related to the late sulfide and electrum assemblage. The H20-NaCI $\pm$ $CO_{2}$ fluids represent fluids evolved through fluid unmixing of an $H_{2}O-CO_{2}-CH_{4}-NaCl$fluids due to decreases in fluid pressure and influenced of deepcirculated meteoric waters possibly related to uplift and unloading of the mineralizing suites. Calculated sulfur isotope compositions (${\delta}^{34}S_{fluid}$) of hydrothermal fluids (1.8-4.9$\textperthousand$) indicate that ore sulfur was derived from an igneous source. Measured and calculated oxygen and hydrogen isotope compositions (${\delta}^{18}O_{I120}$, ${\delta}D$) of ore fluids (-5.9~10.9$\textperthousand$, -102~-87$\textperthousand$) indicate that mesothermal auriferous fluids at Samkwang gold-silver deposits were likely mixtures of $H_{2}O$-rich, isotopically less evolved meteoric water and magmatic fluids.

A Study on Luxury Prohibition of Korean Personal Ornaments (한국장신구의 사치 금제 고찰)

  • 추원교
    • Archives of design research
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    • v.2 no.1
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    • pp.43-62
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    • 1989
  • The luxury is the expression of human being's ornament instinct. In this study, in order to grasp the moulding system of the Korean's personal ornaments, the process of luxury prohibition was reviewed to search for to which direction the ornaments developed in the frame of the prohibited style connected closely to the character of the personal ornaments. The proiod was fixed from the old society to the late Chosun dynasty era. The beginning of the luxury in Korea seems to be the start of the luxury burial at the time of funeral in the age of Koguryo., In the era of Koguryo, 10th year of King Dongmyung (B. C. 28), in the era of Baekje, 27th year of King Koi(260), the prohibition of dress regulation and the style of dress were conducted. The prohibition of personal ornaments in Silla was started from King Bup:Heung, and in the 9th year of King Heung-Duk, the prohibition was conducted in order to correct the luxury of the nobles and set up the social discipline. In the 11 th of King Il-Sung-Ni-Sa-Kum, the use of gold, silver and jade was prohibited in the civilian circles. The prohibition of Silla was succeeded to Koryo era, and in the 7th year of King Kwangjong(956), the system of Baekgwan Gongbok(uniform for government officials) was set up, and the system of Sasek Gongbok(four color official uniform) was set up in the 11 th year of the same King, and the prohibition of the personal ornaments such as crown and band is considred to have been conducted. The prohibition of gold and silver was conducted in the first year of King Sungjong(982), and in the 4th year of King Chungryul(l260), the order of wearing the dress and hat in accordance with the Yusan dynasty and the Mongolian customs were widely circulated in the royal court and vivilian circles. The strong influence of Mongolia made the taste of the traditional personal ornaments laste. The personal ornaments were used for the nobles until the age of the Unified Sillar but even the common people could use them in case they were rich, and such a circumstances made the use of foreign goods inflated. The prohibition of Koryo era was aimed at the prohibition of the foreign goods of luxury, and the classification of the social status.In the age of Chosun Dynasty, the production of gold and silver was feeble indeed but the oute reason of the prohibition was to eradicate the luxurious tendency, elevate the custom of eradicate the luxurious tendency, elevate the custom of thrift, and moreover, the gold, silver and jade were no the products of Korea and the prohibition was conducted but the true reason was afor the tribute tt China and the classification of status. The prohibition of Chosun dynasty was conducted first in the June of the 3rd year of King Taejo The major contents of prohibition was no use of gold, silver and jade, coral, agate, amber, etc. of th, wives of the Dang-Sang-Kwan (Court Nobleman) or their sons and daughters, and the same pheno menon was common even at the time of marriage. The people engaged in the secret trade there of wert beheaded. The personal ornaments in the prohibition were the pendent trinket, Binyo (crossbar) ceremonial ornamental hat, ring, earring, ornamental knife, hat string, hat ornament, belt, etc. Thl luxurious marriage expenses out of the luxury was severe, and lose of the marriageable age because 0 non-preparing the marriage goods was the national evil. The prohibition oC luxury was hard to bt kept to the nobles or rich people, the same as old days and present days. The prohibition of th{ luxury and personal ornaments of Korea had nothing to do with the commons, and it was limited tc the nobles and rich people. The prohibition was aimed to cultivating the custom of frugality by eradicating the luxurious atmosphere, but it was chiefly due to the tribute to the China and tht discrimination of the. status. We can say that the recent personal ornament was the flower of handi craft industry bloomed in the prohibition and regulation.

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