TY  - JOUR
AU  - Štrbac, Nada
AU  - Sokić, Miroslav
AU  - Mitovski, Aleksandra
AU  - Živković, Dragana
AU  - Marković, Branislav
AU  - Andrić, Velibor
PY  - 2015
UR  - https://ritnms.itnms.ac.rs/handle/123456789/373
AB  - U radu su prikazani rezultati DTA/TG analize polimetaličnog sulfidnog koncentrata bakra iz rudnog ležišta 'Veliki Krivelj' (Srbija) u temperaturnom intervalu 25 - 1000 °C, na osnovu koje je predložen mehanizam oksidacije prisutnih sulfida u atmosferi vazduha na povišenim temperaturama. Kao potvrda predloženom mehanizmu, u radu su prezentovani rezultati EDXRF analize polaznog uzorka, XRD analize polaznog uzorka i produkata oksidacije na 550 i 950°C i rezultati SEM/EDS analize polaznog uzorka i produkata oksidacije na 675 °C. Upoređivanjem eksperimentalnih rezultata dobijenih XRD i DTA/TG analizom može se zaključiti da se proces oksidacije ispitivanog koncentrata može podeliti u dva stupnja: prvi stupanj čine reakcije oksidacije sulfida sa karakterističnim egzotermnim efektima ispod 650 °C, dok obrazovanje sulfata i oksisulfata i njihovo razlaganje do oksida bakra i železa čini drugi stupanj, praćen karakterističnim endotermnim efektima na višim temperaturama. Kinetička analiza procesa oksidacije ispitivanog koncentrata izvršena je po metodama Kissingera i Ozawe u neizotermskim uslovima. Rezultati kinetičkih ispitivanja i vrednosti energije aktivacije pokazali su da se proces oksidacije u celom ispitivanom temperaturnom intervalu nalazi u kinetičkoj oblasti.
AB  - The paper presents DTA/TG results of polymetallic sulphide copper concentrate from the mine 'Veliki Krivelj' (Serbia) at 25-1000 °C. The reaction mechanism at elevated temperatures was proposed. As confirmation to the proposed mechanism, the results of EDXRF and, XRD analysis of the initial sample and the oxidation products at 550 and 950 °C, and the results of SEM/EDS analysis of the initial sample and the oxidation products at 675 ° C were presented. It can be concluded that the oxidation process goes through sulfide oxidation with characteristic exothermic effects, followed by sulfates and oxy- sulfates formation and their. Kinetic analysis of the oxidation process concentrates the test was performed according to the methods of Kissinger and Ozawa in non-isothermal conditions. The results of kinetic studies have shown that the oxidation process in the whole investigated temperature range is located in the kinetic field.
PB  - Savez inženjera i tehničara Srbije, Beograd
T2  - Tehnika
T1  - Određivanje mehanizma i kinetičkih parametara oksidacije sulfidnih minerala bakra na povišenim temperaturama
T1  - Determination the mechanism and kinetic parameters of copper sulfide minerals oxidation at elevated temperatures
EP  - 65
IS  - 1
SP  - 60
VL  - 70
DO  - 10.5937/tehnika1501060S
UR  - conv_16
ER  - 

@article{
author = "Štrbac, Nada and Sokić, Miroslav and Mitovski, Aleksandra and Živković, Dragana and Marković, Branislav and Andrić, Velibor",
year = "2015",
abstract = "U radu su prikazani rezultati DTA/TG analize polimetaličnog sulfidnog koncentrata bakra iz rudnog ležišta 'Veliki Krivelj' (Srbija) u temperaturnom intervalu 25 - 1000 °C, na osnovu koje je predložen mehanizam oksidacije prisutnih sulfida u atmosferi vazduha na povišenim temperaturama. Kao potvrda predloženom mehanizmu, u radu su prezentovani rezultati EDXRF analize polaznog uzorka, XRD analize polaznog uzorka i produkata oksidacije na 550 i 950°C i rezultati SEM/EDS analize polaznog uzorka i produkata oksidacije na 675 °C. Upoređivanjem eksperimentalnih rezultata dobijenih XRD i DTA/TG analizom može se zaključiti da se proces oksidacije ispitivanog koncentrata može podeliti u dva stupnja: prvi stupanj čine reakcije oksidacije sulfida sa karakterističnim egzotermnim efektima ispod 650 °C, dok obrazovanje sulfata i oksisulfata i njihovo razlaganje do oksida bakra i železa čini drugi stupanj, praćen karakterističnim endotermnim efektima na višim temperaturama. Kinetička analiza procesa oksidacije ispitivanog koncentrata izvršena je po metodama Kissingera i Ozawe u neizotermskim uslovima. Rezultati kinetičkih ispitivanja i vrednosti energije aktivacije pokazali su da se proces oksidacije u celom ispitivanom temperaturnom intervalu nalazi u kinetičkoj oblasti., The paper presents DTA/TG results of polymetallic sulphide copper concentrate from the mine 'Veliki Krivelj' (Serbia) at 25-1000 °C. The reaction mechanism at elevated temperatures was proposed. As confirmation to the proposed mechanism, the results of EDXRF and, XRD analysis of the initial sample and the oxidation products at 550 and 950 °C, and the results of SEM/EDS analysis of the initial sample and the oxidation products at 675 ° C were presented. It can be concluded that the oxidation process goes through sulfide oxidation with characteristic exothermic effects, followed by sulfates and oxy- sulfates formation and their. Kinetic analysis of the oxidation process concentrates the test was performed according to the methods of Kissinger and Ozawa in non-isothermal conditions. The results of kinetic studies have shown that the oxidation process in the whole investigated temperature range is located in the kinetic field.",
publisher = "Savez inženjera i tehničara Srbije, Beograd",
journal = "Tehnika",
title = "Određivanje mehanizma i kinetičkih parametara oksidacije sulfidnih minerala bakra na povišenim temperaturama, Determination the mechanism and kinetic parameters of copper sulfide minerals oxidation at elevated temperatures",
pages = "65-60",
number = "1",
volume = "70",
doi = "10.5937/tehnika1501060S",
url = "conv_16"
}

Štrbac, N., Sokić, M., Mitovski, A., Živković, D., Marković, B.,& Andrić, V.. (2015). Određivanje mehanizma i kinetičkih parametara oksidacije sulfidnih minerala bakra na povišenim temperaturama. in Tehnika
Savez inženjera i tehničara Srbije, Beograd., 70(1), 60-65.
https://doi.org/10.5937/tehnika1501060S
conv_16

Štrbac N, Sokić M, Mitovski A, Živković D, Marković B, Andrić V. Određivanje mehanizma i kinetičkih parametara oksidacije sulfidnih minerala bakra na povišenim temperaturama. in Tehnika. 2015;70(1):60-65.
doi:10.5937/tehnika1501060S
conv_16 .

Štrbac, Nada, Sokić, Miroslav, Mitovski, Aleksandra, Živković, Dragana, Marković, Branislav, Andrić, Velibor, "Određivanje mehanizma i kinetičkih parametara oksidacije sulfidnih minerala bakra na povišenim temperaturama" in Tehnika, 70, no. 1 (2015):60-65,
https://doi.org/10.5937/tehnika1501060S .,
conv_16 .

TY  - JOUR
AU  - Živković, D.
AU  - Štrbac, Nada
AU  - Sokić, Miroslav
AU  - Andrić, Velibor
AU  - Jovanović, I.
AU  - Jovičić, Marija
AU  - Anđelić, B.
AU  - Radosavljević, Slobodan
PY  - 2014
UR  - https://ritnms.itnms.ac.rs/handle/123456789/317
AB  - Preliminary results of physicochemical investigation of some archaeometallurgical findings from Kmpije locality in vicinity of Bor (Serbia) are presented in this paper. Ancient samples of prehistoric origin were investigated using different instrumental analytic methods-chemical, differential thermal, X-ray diffraction, and energy dispersive X-ray fluorescence analysis. Obtained results indicate to the presence of ancient metallurgical activities, so locality Kmpije may be considered as an archaeometallurgical site, which should be investigated more in future for more precise details.
PB  - Springer, Dordrecht
T2  - Journal of Thermal Analysis and Calorimetry
T1  - Physicochemical investigation of some archaeometallurgical findings from locality Kmpije (Bor, Serbia)
EP  - 1373
IS  - 2
SP  - 1369
VL  - 118
DO  - 10.1007/s10973-014-4050-6
UR  - conv_712
ER  - 

@article{
author = "Živković, D. and Štrbac, Nada and Sokić, Miroslav and Andrić, Velibor and Jovanović, I. and Jovičić, Marija and Anđelić, B. and Radosavljević, Slobodan",
year = "2014",
abstract = "Preliminary results of physicochemical investigation of some archaeometallurgical findings from Kmpije locality in vicinity of Bor (Serbia) are presented in this paper. Ancient samples of prehistoric origin were investigated using different instrumental analytic methods-chemical, differential thermal, X-ray diffraction, and energy dispersive X-ray fluorescence analysis. Obtained results indicate to the presence of ancient metallurgical activities, so locality Kmpije may be considered as an archaeometallurgical site, which should be investigated more in future for more precise details.",
publisher = "Springer, Dordrecht",
journal = "Journal of Thermal Analysis and Calorimetry",
title = "Physicochemical investigation of some archaeometallurgical findings from locality Kmpije (Bor, Serbia)",
pages = "1373-1369",
number = "2",
volume = "118",
doi = "10.1007/s10973-014-4050-6",
url = "conv_712"
}

Živković, D., Štrbac, N., Sokić, M., Andrić, V., Jovanović, I., Jovičić, M., Anđelić, B.,& Radosavljević, S.. (2014). Physicochemical investigation of some archaeometallurgical findings from locality Kmpije (Bor, Serbia). in Journal of Thermal Analysis and Calorimetry
Springer, Dordrecht., 118(2), 1369-1373.
https://doi.org/10.1007/s10973-014-4050-6
conv_712

Živković D, Štrbac N, Sokić M, Andrić V, Jovanović I, Jovičić M, Anđelić B, Radosavljević S. Physicochemical investigation of some archaeometallurgical findings from locality Kmpije (Bor, Serbia). in Journal of Thermal Analysis and Calorimetry. 2014;118(2):1369-1373.
doi:10.1007/s10973-014-4050-6
conv_712 .

Živković, D., Štrbac, Nada, Sokić, Miroslav, Andrić, Velibor, Jovanović, I., Jovičić, Marija, Anđelić, B., Radosavljević, Slobodan, "Physicochemical investigation of some archaeometallurgical findings from locality Kmpije (Bor, Serbia)" in Journal of Thermal Analysis and Calorimetry, 118, no. 2 (2014):1369-1373,
https://doi.org/10.1007/s10973-014-4050-6 .,
conv_712 .

TY  - JOUR
AU  - Mitrović, Branislava
AU  - Vitorović, Gordana
AU  - Jovanović, Milijan
AU  - Lazarević-Macanović, Mirjana
AU  - Andrić, Velibor
AU  - Stojanović, Mirjana
AU  - Daković, Aleksandra
AU  - Vitorović, Duško
PY  - 2014
UR  - https://ritnms.itnms.ac.rs/handle/123456789/297
AB  - The aim of the present study was to investigate the distribution of uranium (uranyl nitrate hexahydrate, UN) in muscle and organs (kidney, liver, and brain) of broilers, after a 7-day contamination with UN and administration of two different adsorbents (organobentonite and organozeolite). The birds were contaminated during 7 days with 25 mg/UN per day. Adsorbents were given via gastric tube, immediately after contamination with UN. In group 1 that did not receive any adsorbents, histopathological changes in the contaminated broilers were observed in small intestine, liver, and kidney in the form of necrosis of intestinal villi, oedema and cytoplasmic vacuolation of hepatocytes, and dystrophic changes in the kidney tubules epithelium. Organobentonite administered via gastric tube (group 2) reduced uranium distribution by 66 % in kidney, 81 % in liver, and 34 % in brain. In group 3, administration of organozeolite reduced uranium distribution by 67 % in kidney, 68 % in liver, and 49 % in brain. In groups 2 and 3, where the broilers received adsorbents immediately after the UN contamination, no histopathological lesions were observed.
PB  - Springer, New York
T2  - Radiation and Environmental Biophysics
T1  - Uranium distribution in broiler organs and possibilities for protection
EP  - 157
IS  - 1
SP  - 151
VL  - 53
DO  - 10.1007/s00411-013-0496-3
UR  - conv_682
ER  - 

@article{
author = "Mitrović, Branislava and Vitorović, Gordana and Jovanović, Milijan and Lazarević-Macanović, Mirjana and Andrić, Velibor and Stojanović, Mirjana and Daković, Aleksandra and Vitorović, Duško",
year = "2014",
abstract = "The aim of the present study was to investigate the distribution of uranium (uranyl nitrate hexahydrate, UN) in muscle and organs (kidney, liver, and brain) of broilers, after a 7-day contamination with UN and administration of two different adsorbents (organobentonite and organozeolite). The birds were contaminated during 7 days with 25 mg/UN per day. Adsorbents were given via gastric tube, immediately after contamination with UN. In group 1 that did not receive any adsorbents, histopathological changes in the contaminated broilers were observed in small intestine, liver, and kidney in the form of necrosis of intestinal villi, oedema and cytoplasmic vacuolation of hepatocytes, and dystrophic changes in the kidney tubules epithelium. Organobentonite administered via gastric tube (group 2) reduced uranium distribution by 66 % in kidney, 81 % in liver, and 34 % in brain. In group 3, administration of organozeolite reduced uranium distribution by 67 % in kidney, 68 % in liver, and 49 % in brain. In groups 2 and 3, where the broilers received adsorbents immediately after the UN contamination, no histopathological lesions were observed.",
publisher = "Springer, New York",
journal = "Radiation and Environmental Biophysics",
title = "Uranium distribution in broiler organs and possibilities for protection",
pages = "157-151",
number = "1",
volume = "53",
doi = "10.1007/s00411-013-0496-3",
url = "conv_682"
}

Mitrović, B., Vitorović, G., Jovanović, M., Lazarević-Macanović, M., Andrić, V., Stojanović, M., Daković, A.,& Vitorović, D.. (2014). Uranium distribution in broiler organs and possibilities for protection. in Radiation and Environmental Biophysics
Springer, New York., 53(1), 151-157.
https://doi.org/10.1007/s00411-013-0496-3
conv_682

Mitrović B, Vitorović G, Jovanović M, Lazarević-Macanović M, Andrić V, Stojanović M, Daković A, Vitorović D. Uranium distribution in broiler organs and possibilities for protection. in Radiation and Environmental Biophysics. 2014;53(1):151-157.
doi:10.1007/s00411-013-0496-3
conv_682 .

Mitrović, Branislava, Vitorović, Gordana, Jovanović, Milijan, Lazarević-Macanović, Mirjana, Andrić, Velibor, Stojanović, Mirjana, Daković, Aleksandra, Vitorović, Duško, "Uranium distribution in broiler organs and possibilities for protection" in Radiation and Environmental Biophysics, 53, no. 1 (2014):151-157,
https://doi.org/10.1007/s00411-013-0496-3 .,
conv_682 .

TY  - JOUR
AU  - Živković, Dragana
AU  - Štrbac, Nada
AU  - Sokić, Miroslav
AU  - Andrić, Velibor
AU  - Anđelić, Branka
AU  - Jovanović, Igor
AU  - Jovičić, Marija
AU  - Nikolić, Dušica
PY  - 2012
UR  - https://ritnms.itnms.ac.rs/handle/123456789/235
AB  - Bor and its surroundings are well known for long and rich tradition in mining and metallurgical activities, as well as by numerous archaeometallurgical localities. The results of investigation of archaeometallurgical findings from Šetaće and Paulešti localities near Bor are presented in this paper. Research of slag samples was done using chemical analysis, DTA, XRD and EDXRF in order to confirm early metallurgical works at mentioned two localities.
PB  - Savez inženjera metalurgije Srbije, Beograd
T2  - Metallurgical & Materials Engineering
T1  - Physico-chemical characterization of archaeometallurgical findings from two localities near Bor (Serbia)
EP  - 164
IS  - 2
SP  - 159
VL  - 18
UR  - conv_478
ER  - 

@article{
author = "Živković, Dragana and Štrbac, Nada and Sokić, Miroslav and Andrić, Velibor and Anđelić, Branka and Jovanović, Igor and Jovičić, Marija and Nikolić, Dušica",
year = "2012",
abstract = "Bor and its surroundings are well known for long and rich tradition in mining and metallurgical activities, as well as by numerous archaeometallurgical localities. The results of investigation of archaeometallurgical findings from Šetaće and Paulešti localities near Bor are presented in this paper. Research of slag samples was done using chemical analysis, DTA, XRD and EDXRF in order to confirm early metallurgical works at mentioned two localities.",
publisher = "Savez inženjera metalurgije Srbije, Beograd",
journal = "Metallurgical & Materials Engineering",
title = "Physico-chemical characterization of archaeometallurgical findings from two localities near Bor (Serbia)",
pages = "164-159",
number = "2",
volume = "18",
url = "conv_478"
}

Živković, D., Štrbac, N., Sokić, M., Andrić, V., Anđelić, B., Jovanović, I., Jovičić, M.,& Nikolić, D.. (2012). Physico-chemical characterization of archaeometallurgical findings from two localities near Bor (Serbia). in Metallurgical & Materials Engineering
Savez inženjera metalurgije Srbije, Beograd., 18(2), 159-164.
conv_478

Živković D, Štrbac N, Sokić M, Andrić V, Anđelić B, Jovanović I, Jovičić M, Nikolić D. Physico-chemical characterization of archaeometallurgical findings from two localities near Bor (Serbia). in Metallurgical & Materials Engineering. 2012;18(2):159-164.
conv_478 .

Živković, Dragana, Štrbac, Nada, Sokić, Miroslav, Andrić, Velibor, Anđelić, Branka, Jovanović, Igor, Jovičić, Marija, Nikolić, Dušica, "Physico-chemical characterization of archaeometallurgical findings from two localities near Bor (Serbia)" in Metallurgical & Materials Engineering, 18, no. 2 (2012):159-164,
conv_478 .

TY  - JOUR
AU  - Štrbac, Nada
AU  - Mitovski, Aleksandra
AU  - Mihajlović, Ivan
AU  - Vuković, Milovan
AU  - Sokić, Miroslav
AU  - Andrić, Velibor
PY  - 2012
UR  - https://ritnms.itnms.ac.rs/handle/123456789/221
AB  - Problemi koji se odnose na industrijsko zagađenje, iz godine u godinu postaju sve intezivniji i značajniji, kako na lokalnom, tako i na globalnom nivou. Osnovni razlog su emisije različitih zagađujućih materija koje nastaju kao posledice industrijskih aktivnosti. Problemi koji nastaju tokom ovih aktivnosti su zagađenje voda, zagađenje vazduha, stvaranje opasnog otpada itd. Priroda emisije i uticaj industrije na sredinu, u velikoj meri zavisi od specifičnosti same industrije. Tehnologija pirometalurškog tretmana koncentrata bakra po konvencionalnom postupku, koja se još uvek koristi u pogonima Topionice u Boru, dovela je do značajne degradacije stanja životne sredine u Boru i okolini. Smanjenje koncentracije bakra u domaćim rudnim ležištima dovela je do neophodnosti prerade rude sa oboda već eksploatisanih rudnih tela u kojima je povećana koncentracija štetnih primesa i pratioca bakra, u prvom redu: Zn, Pb, As, Cd, Hg, Ni, i drugih. U regionu Bora i okoline, ova problematika postaje sve značajnija sa stanovišta buduće ekstrakcije bakra iz domaćih koncentrata. Naime, u pojedinim, još uvek neeksplatisanim, rudnim nalazištima u okolini Bora se nalazi velika količina bakra, ali sa povišenim sadržajem štetnih komponenti.
AB  - Recently, the problems relating to the industrial pollution have become more intensive and important at local as well as global level. The primary reason is an emission of polluting substances that appear as a consequence of various industrial activities. These activities produce the whole range of harms to the environment such as: water pollution, air pollution, hazardous waste production etc. The scope of emission of pollutants and industrial affect on the environment depend on specific characteristics of various industries. Pyrometallurgical treatment of copper concentrates, a conventional technological process, still used in the Copper Smelter in Bor, caused serious damages in the environment (in Bor as well in the region). In addition, the decrease of a copper content in domestic row minerals led to the necessity of treatment ores from the periphery (already exploited mineral ores) with an increased concentrations of harm components and metals tied to copper; first of all, Zn, Pb, As, Cd, Hg, Ni and others. In the Bor region this problem has become more important in regard to the future extraction of concentrates from domestic sources. Namely, in some copper minerals, recently discovered and, hence, not exploited, a significant amount of copper with higher contents of pollutants is present.
PB  - Naučno-stručno društvo za zaštitu životne sredine Srbije - Ecologica, Beograd
T2  - Ecologica
T1  - Mogućnosti prerade nestandardnih koncentrata bakra i zaštita životne sredine
T1  - Possibilities for treatment of non-standard copper concentrates and environmental protection
EP  - 379
IS  - 67
SP  - 375
VL  - 19
UR  - conv_249
ER  - 

@article{
author = "Štrbac, Nada and Mitovski, Aleksandra and Mihajlović, Ivan and Vuković, Milovan and Sokić, Miroslav and Andrić, Velibor",
year = "2012",
abstract = "Problemi koji se odnose na industrijsko zagađenje, iz godine u godinu postaju sve intezivniji i značajniji, kako na lokalnom, tako i na globalnom nivou. Osnovni razlog su emisije različitih zagađujućih materija koje nastaju kao posledice industrijskih aktivnosti. Problemi koji nastaju tokom ovih aktivnosti su zagađenje voda, zagađenje vazduha, stvaranje opasnog otpada itd. Priroda emisije i uticaj industrije na sredinu, u velikoj meri zavisi od specifičnosti same industrije. Tehnologija pirometalurškog tretmana koncentrata bakra po konvencionalnom postupku, koja se još uvek koristi u pogonima Topionice u Boru, dovela je do značajne degradacije stanja životne sredine u Boru i okolini. Smanjenje koncentracije bakra u domaćim rudnim ležištima dovela je do neophodnosti prerade rude sa oboda već eksploatisanih rudnih tela u kojima je povećana koncentracija štetnih primesa i pratioca bakra, u prvom redu: Zn, Pb, As, Cd, Hg, Ni, i drugih. U regionu Bora i okoline, ova problematika postaje sve značajnija sa stanovišta buduće ekstrakcije bakra iz domaćih koncentrata. Naime, u pojedinim, još uvek neeksplatisanim, rudnim nalazištima u okolini Bora se nalazi velika količina bakra, ali sa povišenim sadržajem štetnih komponenti., Recently, the problems relating to the industrial pollution have become more intensive and important at local as well as global level. The primary reason is an emission of polluting substances that appear as a consequence of various industrial activities. These activities produce the whole range of harms to the environment such as: water pollution, air pollution, hazardous waste production etc. The scope of emission of pollutants and industrial affect on the environment depend on specific characteristics of various industries. Pyrometallurgical treatment of copper concentrates, a conventional technological process, still used in the Copper Smelter in Bor, caused serious damages in the environment (in Bor as well in the region). In addition, the decrease of a copper content in domestic row minerals led to the necessity of treatment ores from the periphery (already exploited mineral ores) with an increased concentrations of harm components and metals tied to copper; first of all, Zn, Pb, As, Cd, Hg, Ni and others. In the Bor region this problem has become more important in regard to the future extraction of concentrates from domestic sources. Namely, in some copper minerals, recently discovered and, hence, not exploited, a significant amount of copper with higher contents of pollutants is present.",
publisher = "Naučno-stručno društvo za zaštitu životne sredine Srbije - Ecologica, Beograd",
journal = "Ecologica",
title = "Mogućnosti prerade nestandardnih koncentrata bakra i zaštita životne sredine, Possibilities for treatment of non-standard copper concentrates and environmental protection",
pages = "379-375",
number = "67",
volume = "19",
url = "conv_249"
}

Štrbac, N., Mitovski, A., Mihajlović, I., Vuković, M., Sokić, M.,& Andrić, V.. (2012). Mogućnosti prerade nestandardnih koncentrata bakra i zaštita životne sredine. in Ecologica
Naučno-stručno društvo za zaštitu životne sredine Srbije - Ecologica, Beograd., 19(67), 375-379.
conv_249

Štrbac N, Mitovski A, Mihajlović I, Vuković M, Sokić M, Andrić V. Mogućnosti prerade nestandardnih koncentrata bakra i zaštita životne sredine. in Ecologica. 2012;19(67):375-379.
conv_249 .

Štrbac, Nada, Mitovski, Aleksandra, Mihajlović, Ivan, Vuković, Milovan, Sokić, Miroslav, Andrić, Velibor, "Mogućnosti prerade nestandardnih koncentrata bakra i zaštita životne sredine" in Ecologica, 19, no. 67 (2012):375-379,
conv_249 .