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Small scale gold mining effects on the miners and local communities in semi-arid region of Ethiopia
Hailemariam Meaza, Mushir Ali, Solomon Hishe, Zbelo Tesfamariam, 2015, izvirni znanstveni članek

Opis: North Ethiopian highlands are traditionally known for gold mining which has been means of livelihood of the rural community. The present work was conducted to investigate socio- economic conditions of gold miners, ways of obtaining the gold, their earning and negative consequences of the gold mining. On the basis of random sampling, 140 miners were interviewed. Moreover, focus group discussions transect walks and practical observations across the mining sites were made with team leaders on different issues of gold mining and its effects. Descriptive statistics was used to compute socio-economic characteristics, gold harvesting, and income dynamics. ANOVA was run to observe variations of income from gold mining and other sources, 2009 to 2012. The positive effects of gold mining for involved people were regarding income, employment, expenditure on education, health and food consumption. On the other hand, conflicting interest, communicable diseases, aggressive child labour, school dropouts, social disruptions and injuries were challenges of the small scale gold mining. The findings highlight that the income generated from small scale gold mining plays a pivotal role in reducing rural poverty. Therefore, providing integrated training for gold miners can mitigate the challenges of small scale gold mining and thereby to improve livelihoods of the small scale gold miners in Ethiopia.
Ključne besede: gold mining, indigenous methods, highlands, society, transaction, Ethiopia
Objavljeno: 16.04.2018; Ogledov: 485; Prenosov: 60
.pdf Celotno besedilo (468,79 KB)
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A life histories approach to gold prospecting and frontier farming in the Brazilian Amazon
Scott William Hoefle, 2009, pregledni znanstveni članek

Opis: In contrast to the usual faceless macro-economic and sociological treatment of development cycles in the Amazon, which at best offer generalities about ‘social actors’ labelled ‘peasants’, ‘ranchers’ and ‘trans-national corporations’, who represent the abstract categories of labour and globalised capital, a human face to frontier processes is offered here. The social and economic sustainability of the shifting back and forth from gold prospecting to family farming on the frontier is evaluated through the eyes of those who experienced it so producing an un- romanticised portrait of prospecting in western Pará during the gold rush of 1961-1990 as well as of frontier farming today. The economic origin and past quality of life of those who left local farms or came from the distant rural zones of impoverished Maranhão are compared and contrasted with that of their passage through the degrading living conditions of gold prospecting and finally with their current situation as struggling but independent frontier farmers in Itaituba and Santarém municipalities.
Ključne besede: Amazon, frontier farming, gold prospecting, quality of life
Objavljeno: 20.03.2018; Ogledov: 558; Prenosov: 64
.pdf Celotno besedilo (102,44 KB)
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Size-dependent effects of gold nanoparticles uptake on maturation and antitumor functions of human dendritic cells in vitro
Sergej Tomić, Nina Ogrinc Potočnik, Rebeka Rudolf, Primož Pelicon, Ivan Anžel, Marjan Rupnik, Jelena Đokić, Saša Vasilijić, Dragana Vučević, Petar Milosavljević, Srđa Janković, Jelena Rajković, Bernd Friedrich, Miodrag Čolić, 2014, izvirni znanstveni članek

Opis: Gold nanoparticles (GNPs) are claimed as outstanding biomedical tools for cancer diagnostics and photo-thermal therapy, but without enough evidence on their potentially adverse immunological effects. Using a model of human dendritic cells (DCs), we showed that 10 nm- and 50 nm-sized GNPs (GNP10 and GNP50, respectively) were internalized predominantly via dynamin-dependent mechanisms, and they both impaired LPS-induced maturation and allostimulatory capacity of DCs, although the effect of GNP10 was more prominent. However, GNP10 inhibited LPS-induced production of IL-12p70 by DCs, and potentiated their Th2 polarization capacity, while GNP50 promoted Th17 polarization. Such effects of GNP10 correlated with a stronger inhibition of LPS-induced changes in Ca2+ oscillations, their higher number per DC, and more frequent extraendosomal localization, as judged by live-cell imaging, proton, and electron microscopy, respectively. Even when released from heat-killed necrotic HEp-2 cells, GNP10 inhibited the necrotic tumor cell-induced maturation and functions of DCs, potentiated their Th2/Th17 polarization capacity, and thus, impaired the DCs% capacity to induce T cell-mediated anti-tumor cytotoxicity in vitro. Therefore, GNP10 could potentially induce more adverse DC-mediated immunological effects, compared to GNP50.
Ključne besede: gold, nanoparticles, antitumor function
Objavljeno: 19.06.2017; Ogledov: 733; Prenosov: 295
.pdf Celotno besedilo (5,60 MB)
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Morphology, aggregation properties, cytocompatibility and anti-inflammatory potential of citrate-stabilized AuNPs prepared by modular Ultrasonic Spray Pyrolysis
Rebeka Rudolf, Peter Majerič, Sergej Tomić, Mohammed Shariq, Urban Ferčec, Bojan Budič, Bernd Friedrich, Dragana Vučević, Miodrag Čolić, 2017, izvirni znanstveni članek

Opis: Ultrasonic Spray Pyrolysis (USP) possesses a great potential for production of higher quantities of gold nanoparticles (AuNPs), thus overcoming the problem of batch-to-batch variations in their properties. Recently, we demonstrated that USP with an additional evaporation chamber (modular USP) led to a better size control of AuNPs. However, their morphology, stability, toxicity, and immunomodulatory properties have not been investigated completely. Here, two types of spherical AuNPs were produced by using different USP parameters, followed by their stabilization in Na-citrate solution. No significant changes in their size, agglomeration, and -potential occurred 3 months after their initial production in citrate solution. However, the conditioning of AuNPs in serum-containing cell culture media for 24 h induced an increase in the AuNPs’ hydrodynamic size and a red shift in their Surface Plasmon Resonance, pointing to their instability in biological media. Cytocompatibility tests showed that the produced AuNPs were internalized by L929 cells and primary human monocytes and were not cytotoxic at the concentrations lower than 200 μg/mL, but they exhibited antiproliferative and anti-inflammatory effects, respectively. AuNPs reduced the percentage of CD14+CD16+ but not CD14lowCD16+ monocytes in vitro and reduced the expression of CD86, HLA-DR, TNF-α, and IL-12/IL-23 by these cells. These results indicate that the anti-inflammatory effects of citrate-capped AuNPs produced by modular USP could be beneficial for their application in the treatment of inflammatory conditions.
Ključne besede: Ultrasonic Spray Pyrolysis, gold nanoparticles, plasmon resonance, monocytes, antiinflammatory effects
Objavljeno: 14.06.2017; Ogledov: 699; Prenosov: 297
.pdf Celotno besedilo (5,41 MB)
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Au-nanoparticle synthesis via ultrasonic spray pyrolysis with a separate evaporation zone
Peter Majerič, Bernd Friedrich, Rebeka Rudolf, 2015, izvirni znanstveni članek

Opis: Some experiments were conducted in connection with the gold-nanoparticle production in an effort to produce a more accurate model for determining the gold-nanoparticle synthesis with a modified ultrasonic spray pyrolysis (USP). As previous experi- ments with gold nanoparticles yielded nanoparticles of various shapes (spherical, triangular, cylindrical, etc.), a focus on synthesizing only spherical nanoparticles is underway, as a mixture of different shapes is difficult to characterize and utilize. One of the factors for the particle formation is droplet evaporation. In an attempt to produce the optimum conditions for droplet evaporation with the solvent diffusion and precipitation, a separate furnace and a separate reaction-gas inlet were used. This modification separates the evaporation stage from the reaction stage, compared to the standard USP set-up. Using relatively low temperatures, from 60 °C up to 140 °C, for the evaporation stage provides for more time and better conditions for the diffusion of the solvent into the center of a droplet and a higher probability of forming a spherical particle.
Ključne besede: nanotehnology, ultrasonic spray pyrolysis, gold, aerosol, TEM microscopy
Objavljeno: 14.03.2017; Ogledov: 870; Prenosov: 357
.pdf Celotno besedilo (752,54 KB)
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Synthesis of Au nanoparticles prepared with ultrasonic spray pyrolysis and hydrogen reduction
Srečko Stopić, Rebeka Rudolf, Jelena Bogovic, Peter Majerič, Miodrag Čolić, Sergej Tomić, Monika Jenko, Bernd Friedrich, 2013, izvirni znanstveni članek

Opis: Golden nanoparticles of different sizes and shapes (spherical, cylindrical, triangular and round) where prepared during a synthesis of gold with ultrasonic spray pyrolysis (USP) and hydrogen reduction. The experimental investigations of the (USP) method were performed with an ultrasonic source of 0.8 MHz and 2.5 MHz, acting on the water solution of HAuCl4 forming aerosols with micron-sized and nanosized droplets. The results of the investigation show that the final shape and size of the Au particles depend on the characteristics of the solution and the frequency of the ultrasound. The second step of synthesizing the Au nanoparticles includes the subsequent thermal decomposition of the aerosol droplets in a hydrogen atmosphere between 260°C and 500°C. The investigations showed that the Au nanoparticles prepared in this way are smaller and more homogeneous.
Ključne besede: gold, ultrasonic spray pyrolysis, reduction, nanoparticles
Objavljeno: 21.12.2015; Ogledov: 1050; Prenosov: 54
.pdf Celotno besedilo (3,17 MB)
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Preparation of Au[sub]2S[sub]3 and nanocrystalline gold by sonochemical method
Matjaž Kristl, Mihael Drofenik, 2003, izvirni znanstveni članek

Opis: We report a new synthesis of ▫$Au_2S_3$▫ by a sonochemical reaction between ▫$Au(CH_3COO)_3$▫ and S in decalin at room temperature in nitrogen atmosphere. When gold acetate is sonicated under similar conditions without the presence of sulfur, nanocrystalline gold is formed. The products were characterised by X-ray powder diffraction, transmission electron microscope and thermal analysis (IG and DSC). The synthesis procedure is substantially simpler than the previously reported methods.
Ključne besede: sonochemistry, sonochemical reactions, gold, sulfides, sonochemical synthesis, nanostructures
Objavljeno: 01.06.2012; Ogledov: 1281; Prenosov: 23
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Gold in the past, today and future
Rebeka Rudolf, Maša Anžel, Evgenija Marković, Miodrag Čolić, Dragoslav Stamenković, 2012, pregledni znanstveni članek

Opis: This paper deals with gold, which is described as a chemical element. Special attention is paid to its physical-chemical properties and, furthermore, where or in what form it can be found in nature. We discuss the role it has played through history and we inform how gold has been developed to the level it has reached today's value. Still more, when gold is broken into nanoparticles, this form could be highly useful for a wide range of processes, including general nanotechnology, electronics manufacturing and the synthesizing of different functional materials. It is important that we know that gold is also used in industry in many engineering applications (contacts in micro-electronics) and medicine (dental alloys, implants).
Ključne besede: gold, physical-chemical properties, nano-particles, applications
Objavljeno: 01.06.2012; Ogledov: 2112; Prenosov: 81
.pdf Celotno besedilo (144,60 KB)
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Grega Pauko, 2010, delo diplomskega seminarja/zaključno seminarsko delo/naloga

Opis: Kot smo lahko videli, je zlato od odkritja okrog 4000 let pr. n. št., do danes pridobivalo na svoji pomembnosti, predvsem v gospodarstvu. Nekaj stoletij po odkritju se pojavijo prvi zlati kovanci, ki so služili za plačilo, in s tem zlato dobi svojo najpomembnejšo vlogo, kot hranilec vrednosti. Skozi zgodovino se je tudi veliko špekuliralo oziroma manipuliralo s cenami zlata. Okrog leta 1900 je t.i zlati standard (valute teh držav so torej vedno ustrezale določeni količini zlata (ali srebra), zaradi česar je bil menjalni tečaj med valutama stabilen) uporabljalo 50 držav. Ta zlati standard se je odpravil leta 1914 zaradi financiranja prve svetovne vojne. Drugi zlato-devizni standard se pojavi leta 1944, s tako imenovanim BrettonWoodskim sporazumom , katerega pa enostransko prekine predsednik ZDA Nixon, zaradi razvrednotenja dolarja. Prodaje in posojanje zlata igrajo torej v procesu manipulacij z zlatom osrednjo vlogo. Ko bo trg spoznal, da centralne banke nimajo več zalog, bo cena zlata neizogibno zrasla, saj se bo odnos ponudba-povpraševanje bistveno poslabšal. Trg zlatih palic je globalni trg. Z zlatimi palicami se lahko trguje po vsem svetu, čeprav je središče trgovanja v Londonu na LBMA. Londonski trg plemenitih kovin je trg veleprodaje, kjer je minimalna količina trgovanja med klienti po navadi 1.000 unč za zlato, ter 50.000 unč za srebro. Zapiski transakcij plemenitih kovin v Londonu segajo v 17. stoletje. Trgovanje na takšnih trgih poteka po nekakšnem utečenem vrstnem redu, za kar skrbi standardna dokumentacija. Priznavanje dokumentacije s strani članov LBMA, pripomore k temu, da ni potrebno vedno znova preverjat pogojev in ostalih pravil, ki so nujna pri bilateralnih sporazumih. Seveda pa je ta trg reguliran s strani FSA. Na teh trgih se trguje z različnimi velikosti zlatih palic. Seveda je izbira s kakšnimi palicami bo trgoval posameznik ali kakšna finančna organizacija, prepuščena lastni izbiri oziroma lastnim zmožnostim. Če se odločimo da začnemo trgovati z zlatimi palicami je pri tem potrebno upoštevat določene kriterije. Kot prvo je potrebno imeti dovolj začetnega kapitala. Potrebno je tudi izbrati najustreznejšega trgovca, izbrati primerno blagovno znamko, preučiti ceno zlata, kje bomo zlato palico hranili, kakšne so možnosti dostave in kakšni so še drugi stroški pri prodaji oziroma nakupu zlate palice. Seveda pa trgovanje ne poteka samo v Londonu. Pomembnejši trgi so še COMEX, BM&F, DMCC, IGE, MCX, TOCOM, SGE, SHFE in CGSE. Kot lahko vidimo je trgovanje z zlatimi palica in drugimi oblikami zlata postala enormna operacija, katere se udeležuje vse več ljudi predvsem zaradi možnosti velikega zaslužka.
Ključne besede: Trgovanje z zlatimi palicami, BrettonWoodski sistem, Gold Pool, Gold Carry Trade, LBMA, Zlata palica
Objavljeno: 26.01.2011; Ogledov: 1614; Prenosov: 108
.pdf Celotno besedilo (248,25 KB)

Boris Hranjec, 2010, diplomsko delo

Opis: Od druge polovice 60-tih let naprej, s pričetkom razvoja rock glasbe, so bile v rock glasbi ustvarjene številne socialnopolitično obarvane pesmi, v katerih so se znameniti rock izvajalci ukvarjali z najrazličnejšimi socialnopolitičnimi temami. Še več, v njihovih pesmih niso pomembna samo socialnopolitično naravnana besedila, ampak tudi glasba sama, ki ima včasih zmožnost izraziti določene situacije, ki jih same besede v tekstu ne morejo. Na primer, glasba, v rock glasbi je to največkrat zvok kitar in bobnov, lahko metaforično predstavi določene situacije, predmete, in celo gibanje teh predmetov (letalo ki leti). Irska skupina U2 vsekakor spada v skupino rock glasbenikov, katerih glasba je socialnopolitično naravnana. V njihovi 30-let dolgi karieri so U2 ustvarili številne, socialnopolitično orientirane pesmi. Interpretirane pesmi v tej diplomski seminarski nalogi so dokaz, da takšne rock pesmi niso zgolj nekakšna nepomembna besedila in glasba, ampak pesmi katerih sporočilo nas uči o nekaterih pomembnih socialnopolitičnih problemih.
Ključne besede: rock glasba, socialnopolitične teme, metafore v glasbi, U2, Sunday Bloody Sunday, Bullet The Blue Sky, Silver & Gold, Miss Sarajevo
Objavljeno: 07.07.2010; Ogledov: 2586; Prenosov: 292
.pdf Celotno besedilo (1,68 MB)

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