Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics

The carbonated hydroxyapatite powder was obtained by reaction of calcium carbonate with ortho-phosphoric acid. The compacted powder samples were sintered in the 800- 1000°C range in dry carbon dioxide atmosphere under atmospheric pressure. It is revealed that ceramics synthesized in such conditions...

Повний опис

Збережено в:
Бібліографічні деталі
Дата:2008
Автори: Tkachenko, M.V., Zyman, Z.Z.
Формат: Стаття
Мова:English
Опубліковано: НТК «Інститут монокристалів» НАН України 2008
Назва видання:Functional Materials
Теми:
Онлайн доступ:http://dspace.nbuv.gov.ua/handle/123456789/136550
Теги: Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
Назва журналу:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Цитувати:Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics // M.V. Tkachenko, Z.Z. Zyman // Functional Materials. — 2008. — Т. 15, № 4. — С. 574-579. — Бібліогр.: 12 назв. — англ.

Репозитарії

Digital Library of Periodicals of National Academy of Sciences of Ukraine
id irk-123456789-136550
record_format dspace
spelling irk-123456789-1365502018-06-17T03:12:16Z Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics Tkachenko, M.V. Zyman, Z.Z. Technology The carbonated hydroxyapatite powder was obtained by reaction of calcium carbonate with ortho-phosphoric acid. The compacted powder samples were sintered in the 800- 1000°C range in dry carbon dioxide atmosphere under atmospheric pressure. It is revealed that ceramics synthesized in such conditions is the AB type carbonated hydroxyapatite. The carbonization kind varies from mainly B type (at relatively low sintering temperatures) to mainly A type (at high ones). The carbonic gas atmosphere did not allow to suppress disintegration of a carbonated apatite at a sintering temperatures above 1100°C, a partial decomposition of the B type apatite occurs with calcium oxide release. As a result, porosity of the ceramics increases and its mechanical properties drop sharply. However, at temperatures below 1100°C, the carbon dioxide favors the activated shrinkage of compacts due to accelerated diffusion migration of the powder particles. In particular, the maximum density of ceramics (~94% from the theoretical value) is reached at 1000°C. Порошок карбонізованого гідроксилапатиту отримано реакцією між карбонатом кальцію та ортофосфорною кислотою. Виготовлені з нього пресовані зразки спікалися в інтервалі температур 800-1000°С у атмосфері сухого діоксиду вуглецю (при нормальному тиску). Кераміка, отримана у такий спосіб, є карбонізованим гідроксилапатитом АЕ-типу. Вид карбонізації змінюється від переважно В-типу при відносно низьких температурах до переважно А-типу - при високих температурах спікання. Вище 1100°С відбувається частковий розпад апатиту В-типу та виділення окису кальцію. При цьому пористість кераміки зростає та різко падають її механічні властивості. При температурах нижче 1100°С атмосфера діоксиду вуглецю сприяє активованій усадці пресовок завдяки прискоренню дифузійної міграції частинок порошку. Зокрема, це приводить до досягнення високої щільності кераміки (~94% від теоретичного значення ГА) при температурі 1000°С. Порошок карбонизированного гидроксилапатита получен путем проведения реакции между карбонатом кальция и ортофосфорной кислотой. Изготовленные из него прессовки спекались в интервале температур 800-1000°С в атмосфере сухого углекислого газа (при нормальном давлении). Керамика, полученная таким способом, является карбонизированным гидроксилапатитом АВ-типа. Вид карбонизации изменяется от преимущественно В-типа при относительно низких температурах до преимущественно А-типа - при высоких температурах спекания. Выше 1100°С происходит частичный распад апатита В-типа и выделение окиси кальция. При этом пористость керамики увеличивается и резко падают ее механические свойства. При температурах нижe 1100°С, атмосфера углекислого газа способствует активированной усадке прессовок благодаря ускорению диффузионной миграции частиц порошка. В частности, это приводит к достижению высокой плотности керамики (~94% от теоретического значения ГА) при температуре 1000°С. 2008 Article Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics // M.V. Tkachenko, Z.Z. Zyman // Functional Materials. — 2008. — Т. 15, № 4. — С. 574-579. — Бібліогр.: 12 назв. — англ. 1027-5495 http://dspace.nbuv.gov.ua/handle/123456789/136550 en Functional Materials НТК «Інститут монокристалів» НАН України
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
language English
topic Technology
Technology
spellingShingle Technology
Technology
Tkachenko, M.V.
Zyman, Z.Z.
Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics
Functional Materials
description The carbonated hydroxyapatite powder was obtained by reaction of calcium carbonate with ortho-phosphoric acid. The compacted powder samples were sintered in the 800- 1000°C range in dry carbon dioxide atmosphere under atmospheric pressure. It is revealed that ceramics synthesized in such conditions is the AB type carbonated hydroxyapatite. The carbonization kind varies from mainly B type (at relatively low sintering temperatures) to mainly A type (at high ones). The carbonic gas atmosphere did not allow to suppress disintegration of a carbonated apatite at a sintering temperatures above 1100°C, a partial decomposition of the B type apatite occurs with calcium oxide release. As a result, porosity of the ceramics increases and its mechanical properties drop sharply. However, at temperatures below 1100°C, the carbon dioxide favors the activated shrinkage of compacts due to accelerated diffusion migration of the powder particles. In particular, the maximum density of ceramics (~94% from the theoretical value) is reached at 1000°C.
format Article
author Tkachenko, M.V.
Zyman, Z.Z.
author_facet Tkachenko, M.V.
Zyman, Z.Z.
author_sort Tkachenko, M.V.
title Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics
title_short Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics
title_full Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics
title_fullStr Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics
title_full_unstemmed Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics
title_sort effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics
publisher НТК «Інститут монокристалів» НАН України
publishDate 2008
topic_facet Technology
url http://dspace.nbuv.gov.ua/handle/123456789/136550
citation_txt Effect of sintering conditions on physical properties of carbonated hydroxyapatite ceramics // M.V. Tkachenko, Z.Z. Zyman // Functional Materials. — 2008. — Т. 15, № 4. — С. 574-579. — Бібліогр.: 12 назв. — англ.
series Functional Materials
work_keys_str_mv AT tkachenkomv effectofsinteringconditionsonphysicalpropertiesofcarbonatedhydroxyapatiteceramics
AT zymanzz effectofsinteringconditionsonphysicalpropertiesofcarbonatedhydroxyapatiteceramics
first_indexed 2025-07-10T01:37:47Z
last_indexed 2025-07-10T01:37:47Z
_version_ 1837222034885574656
fulltext (IIHFW�RI�VLQWHULQJ�FRQGLWLRQV�RQ�SK\VLFDOSURSHUWLHV�RI�FDUERQDWHG�K\GUR[\DSDWLWHFHUDPLFV 0�9�7NDFKHQNR��=�=�=\PDQ 3K\VLFDO�'HSW���9�.DUD]LQ�1DWLRQDO�.KDUNLY�8QLYHUVLW\� ��6YRERG\�6T���������.KDUNLY��8NUDLQH 5HFHLYHG�-XO\�������� 7KH�FDUERQDWHG�K\GUR[\DSDWLWH� SRZGHU�ZDV�REWDLQHG�E\� UHDFWLRQ�RI� FDOFLXP�FDUERQDWH ZLWK� RUWKR�SKRVSKRULF� DFLG�� 7KH� FRPSDFWHG� SRZGHU� VDPSOHV� ZHUH� VLQWHUHG� LQ� WKH� ���Ü �����&�UDQJH�LQ�GU\�FDUERQ�GLR[LGH�DWPRVSKHUH�XQGHU�DWPRVSKHULF�SUHVVXUH��,W�LV�UHYHDOHG WKDW� FHUDPLFV� V\QWKHVL]HG� LQ� VXFK� FRQGLWLRQV� LV� WKH�$%� W\SH� FDUERQDWHG� K\GUR[\DSDWLWH� 7KH� FDUERQL]DWLRQ� NLQG� YDULHV� IURP�PDLQO\� %� W\SH� �DW� UHODWLYHO\� ORZ� VLQWHULQJ� WHPSHUD� WXUHV�� WR� PDLQO\� $� W\SH� �DW� KLJK� RQHV��� 7KH� FDUERQLF� JDV� DWPRVSKHUH� GLG� QRW� DOORZ� WR VXSSUHVV�GLVLQWHJUDWLRQ�RI�D�FDUERQDWHG�DSDWLWH�DW�D�VLQWHULQJ�WHPSHUDWXUHV�DERYH������&� D� SDUWLDO� GHFRPSRVLWLRQ� RI� WKH� %� W\SH� DSDWLWH� RFFXUV� ZLWK� FDOFLXP� R[LGH� UHOHDVH�� $V� D UHVXOW�� SRURVLW\� RI� WKH� FHUDPLFV� LQFUHDVHV� DQG� LWV� PHFKDQLFDO� SURSHUWLHV� GURS� VKDUSO\� +RZHYHU��DW�WHPSHUDWXUHV�EHORZ������&��WKH�FDUERQ�GLR[LGH�IDYRUV�WKH�DFWLYDWHG�VKULQNDJH RI�FRPSDFWV�GXH�WR�DFFHOHUDWHG�GLIIXVLRQ�PLJUDWLRQ�RI�WKH�SRZGHU�SDUWLFOHV��,Q�SDUWLFXODU� WKH�PD[LPXP�GHQVLW\�RI�FHUDPLFV��a�����IURP�WKH�WKHRUHWLFDO�YDOXH��LV�UHDFKHG�DW������&� �º¯º�º}�}ȯ­ºÓÒÏÒ¯ºmÈÓÓº�º��Ò�¯º}°ÒãȹÈ�Ò�È�¹ºã��ËÓ�¹��Ëä�¹¯ºmË�ËÓÒ«�¯ËÈ}�ÒÒ äËÎ���}ȯ­ºÓÈ�ºä�}Èã �Ò«�Ò�º¯�ºÁº°Áº¯Óº®�}Ò°ãº�º®��jÏ�º�ºmãËÓÓ©Ë�ÒÏ�ÓË�º�¹¯Ë°°ºm� }Ò�°¹Ë}ÈãÒ° �m�ÒÓ�˯mÈãË��Ëä¹Ë¯È��¯����Ü�����&�m�È�亰Á˯Ë�°�²º�º���ãË}Ò°ãº�º��ÈÏÈ �¹¯Ò�Óº¯äÈã Óºä��ÈmãËÓÒÒ���z˯ÈäÒ}È��¹ºã��ËÓÓÈ«��È}Òä�°¹º°º­ºä��«mã«Ë�°«�}ȯ­ºÓÒ� ÏÒ¯ºmÈÓÓ©ä��Ò�¯º}°ÒãȹÈ�Ò�ºä�k{��Ò¹È��{Ò��}ȯ­ºÓÒÏÈ�ÒÒ�ÒÏäËÓ«Ë�°«�º��¹¯ËÒä��Ë� °�mËÓÓº�{��Ò¹È�¹¯Ò�º�Óº°Ò�Ëã Óº�ÓÒÏ}Ò²��Ëä¹Ë¯È��¯È²��º�¹¯ËÒä��˰�mËÓÓº�k��Ò¹È�Û ¹¯Ò�m©°º}Ò²��Ëä¹Ë¯È��¯È²�°¹Ë}ÈÓÒ«��{©�Ë������&�¹¯ºÒ°²º�Ò���Ȱ�Ò�Ó©®�¯È°¹È��ȹÈ� �Ò�È�{��Ò¹È�Ò�m©�ËãËÓÒË�º}Ò°Ò�}Èã �Ò«���¯Ò�ª�ºä�¹º¯Ò°�º°� �}˯ÈäÒ}Ò��mËãÒ�ÒmÈË�°«�Ò ¯ËÏ}º�¹È�È ��ËË�ä˲ÈÓÒ�˰}ÒË�°mº®°�mÈ���¯Ò��Ëä¹Ë¯È��¯È²�ÓÒÎË������&��È�亰Á˯È���ãË� }Ò°ãº�º��ÈÏÈ�°¹º°º­°�m�Ë��È}�ÒmÒ¯ºmÈÓÓº®��°È�}Ë�¹¯Ë°°ºmº}�­ãÈ�º�ȯ«��°}º¯ËÓÒ ��ÒÁÁ�� ÏÒºÓÓº®� äÒ�¯È�ÒÒ� �Ȱ�Ò�� ¹º¯º�}È�� {� �Ȱ�Óº°�Ò�� ª�º� ¹¯Òmº�Ò�� }� �º°�ÒÎËÓÒ � m©°º}º® ¹ãº�Óº°�Ò�}˯ÈäÒ}Ò��a�����º���˺¯Ë�Ò�˰}º�º�ÏÓÈ�ËÓÒ«��k��¹¯Ò��Ëä¹Ë¯È��¯Ë������&� 7KH�PLQHUDO�FRPSRQHQW�RI�ERQH�WLVVXHV�LV ILQHO\�GLVSHUVHG�K\GUR[\DSDWLWH� �+$��ZKLFK FRQWDLQV� QXPHURXV� LPSXULWLHV�� 7KHUHIRUH� WKH� FKHPLFDO� FRPSRVLWLRQ� RI� ERQH� LPSODQWV VKRXOG�EH�FRQVLVWHQW�DV�PXFK�DV�SRVVLEOH�WR WKDW� RI� ELRORJLFDO� DSDWLWH� LQ� RUGHU� WR� LP� SURYH�WKH�ELRORJLFDO�UHVSRQVH�RI�RUJDQLVP�WR WKH� +$� LPSODQWV�� 6LQFH� WKH� LPSXULWLHV� DUH YHU\�GLIIHUHQW�LQ�FKHPLFDO�QDWXUH��LW�LV�IHD� VLEOH�WR�LQWURGXFH�RQO\�LPSXULWLHV�SUHVHQW�LQ ERQH�DW�KLJKHVW� FRQFHQWUDWLRQV�ZKHQ�VWXG\� LQJ� V\VWHPDWLFDOO\� WKH� ERQH� LPSODQWV� LQ YLYR�� )LUVW� RI� DOO�� WKHVH� DUH� FDUERQDWH� LRQV KDYLQJ�FRQFHQWUDWLRQ�LQ�WKH�ERQH��Ü��ZW��� >����@�� 7KH� FDUERQDWH� LRQV� PD\� KDYH� RFFX� SLHG�WZR�NLQGV�RI�SRVLWLRQV�LQ�WKH�+$�VWUXF� WXUH� >�Ü�@��7KH� ILUVW� DUH� WKH� VLWHV� RFFXSLHG E\�32���� LRQV� IRUPLQJ� WKH� IUDPH� RI� FU\VWDO ODWWLFH� �VR� FDOOHG� %� W\SH� VXEVWLWXWLRQ��� WKH RWKHU� DUH� VLWHV� RI�2+±� JURXSV� �$� W\SH� VXE� VWLWXWLRQ���7KH�VXEVWLWXWLRQ�RI�WKH�ERWK�SRVL� WLRQV� LV� QRW� LVRPRUSKRXV� LQ� WKH� EDODQFH� RI LRQ�FKDUJH�DQG�VL]H��7KXV��YDULRXV�NLQGV�RI VWUXFWXUDO� GHIHFWV� DSSHDU� GXULQJ� IRUPDWLRQ )XQFWLRQDO�0DWHULDOV�����1R��������� �������Û�,QVWLWXWH�IRU�6LQJOH�&U\VWDOV ��� )XQFWLRQDO�PDWHULDOV������������� RI�D� FDUERQDWHG�+$��ZKLFK�PD\�DIIHFW�FRQ� VLGHUDEO\� WKH� PHFKDQLVP� RI� OLQNDJH� DW� WKH LPSODQW�WLVVXH� LQWHUIDFH� DQG�� FRQVHTXHQWO\� WKH�ELRDFWLYLW\�RI�WKH�LPSODQW� 7KH� ELRORJLFDO� LPSODQWV� DUH� XVXDOO\� FH� UDPLF�DQG�QRW�SRZGHU�SURGXFWV��7KLV�LV�GXH WR� WKH� IDFW� WKDW� SRZGHUV� DUH� HDVLO\�ZDVKHG RXW�RI�WKH�ERQH�GHIHFW�E\�ERG\�OLTXLGV�ZKLOH WKH� FHUDPLFV� DUH� UHVLVWDQW� DJDLQVW� WKRVH� +RZHYHU�� VRPH� GLIILFXOWLHV� DULVH� LQ� WKH� FH� UDPLFV� SUHSDUDWLRQ� IURP� FDUERQDWHG� +$ �&+$�� SRZGHU�� FDXVHG� E\� WKH� IDFW� WKDW� WKH DFWLYH� VLQWHULQJ� WHPSHUDWXUH� H[FHHGV� WKH &+$� GHFRPSRVLWLRQ� WHPSHUDWXUH�� 7KH� ILQDO SURGXFW�LQ�WKLV�FDVH�LV�XVXDOO\�R[\K\GUR[\D� SDWLWH� ZKLFK� LV� ELRDFWLYH� EXW� KDV� D� UDWKHU ORZ� UHVRUSWLRQ� UDWH� LQ� ELRORJLFDO� HQYLURQ� PHQW�� 7KHUHIRUH�� WR� SUHSDUH� DQ� DSSURSULDWH IXQFWLRQDO� FHUDPLFV�� WKH� SURFHVVLQJ� FRQGL� WLRQV�VKRXOG�KLQGHU�WKH�GHFRPSRVLWLRQ�SURF� HVV�RU�DW�OHDVW�GHFHOHUDWH�LW��2QH�RI�WKH�VLP� SOHVW�GHFLVLRQV�ZDV�IRXQG�WR�EH�WKH�VLQWHULQJ LQ�&2��DWPRVSKHUH�>�Ü�@� :HW�DQG�GU\�FDUERQ�GLR[LGH�DWPRVSKHUHV ZHUH� WHVWHG��$� FRPSOH[� UHODWLRQ� RI� WKH� LP� SXULW\�FRPSRVLWLRQ�RI�WKH�LQLWLDO�SRZGHU�DQG WKH� NLQG� RI� JDVHRXV� DWPRVSKHUH� RQ� WKH� RQH KDQG� DQG� WKH� VLQWHULQJ� FKDUDFWHULVWLFV� DQG WKH�SURSHUWLHV� RI� WKH�FHUDPLFV�RQ� WKH�RWKHU RQH��6R��LW�ZDV�VKRZQ�>�@�WKDW�WKH�WHPSHUD� WXUH�GHSHQGHQFH�RI�WKH�FRPSDFW�VKULQNDJH�LV LQGHSHQGHQW� RI� WKH� VLQWHULQJ� DWPRVSKHUH �ZKHWKHU� EHLQJ� DLU� RU� ZHW� RU� GU\� FDUERQ GLR[LGH���:KHQ� WKH� FRPSDFW� FRQWDLQV�&2��� JURXSV�� WKH� FDUERQL]DWLRQ� H[WHQW� RI� +$ SRZGHU� LQ� D� FRPSDFW� HIIHFWV� GHFLVLYHO\� WKH SURFHVV� DFFHOHUDWLRQ� ZKLOH� WKH� DWPRVSKHUH SOD\V� D� VWDELOL]LQJ� SDUW�� +RZHYHU�� WKH PHFKDQLVP�RI�WKH�GHQVLILFDWLRQ�KDV�QRW�EHHQ FODULILHG�XS�WR�QRZ� 7KH� DLP� RI� WKLV� ZRUN� ZDV� WR� VWXG\� WKH HIIHFW�RI�WHPSHUDWXUH�FRQGLWLRQV�RQ�WKH�VLQ� WHULQJ� RI� FRPSDFWHG� &+$� LQ� &2�� DWPRV� SKHUH� DQG� WR� ILQG� DQG� H[SODQDWLRQ� RI� WKH VLQWHULQJ�PHFKDQLVP� 7KH�SUHFLSLWDWH�ZDV�SUHSDUHG�E\�UHDFWLRQ RI� FDOFLXP� FDUERQDWH� �VSHFLDO� SXULW\� JUDGH� 0HUFN�� DQG� RUWKR�SKRVSKRULF� DFLG� �DQDO\WL� FDO�SXULW\�JUDGH���7KH�RUWKR�SKRVSKRULF�DFLG VROXWLRQ�ZDV� SRXUHG� UDSLGO\� LQWR� D� DTXHRXV FDOFLXP� FDUERQDWH� VXVSHQVLRQ� XQGHU� FRQ� WLQXRXV�VWLUULQJ��7KH�V\QWKHWLF�UHDFWLRQ�SUR� FHHGHG� DW� ���&� IRU� ��� K� XQWLO� QHXWUDO� S+ YDOXH� ZDV� DWWDLQHG�� 7KH� SUHFLSLWDWH� ZDV WKHQ� LVRODWHG�E\�FHQWULIXJDWLRQ��GULHG� LQ�DQ RYHQ�DW����&��JURXQGHG� LQ�D�SRUFHODLQ�PRU� WDU��DQG�VLHYHG�WKURXJK�D�����PP�VLHYH��7KH FRPSDFWV� IRU� VLQWHULQJ� ZHUH� SUHSDUHG� E\ VLQJOH�D[LDO� SUHVVLQJ� LQ� D� VWHHO� PRXOG�� WKH FRPSDFWLQJ� SUHVVXUH� EHLQJ� ���� 03D�� 7KH VDPSOHV�ZHUH�VLQWHUHG�LQ�GU\�FDUERQ�GLR[LGH IRU� �� K� DW� ���Ü�����&� DW� D� ����&� VWHSV� )LYH� VHULHV� RI� WKH� VDPSOHV� ���� SLHFHV� LQ HDFK��ZHUH�SUHSDUHG� ;�UD\� PHDVXUHPHQWV� ZHUH� FDUULHG� RXW XVLQJ�D�3KLOLSV�$3':��&�GLIIUDFWRPHWHU�LQ &X.D� UDGLDWLRQ� LQ� WKH� �T� DQJOH� UDQJH� ��Ü ���� ZLWK� VFDQQLQJ� SLWFK� RI� ������ DQG� VFDQ� QLQJ� WLPH� ���� V�� ,5� VSHFWUD�ZHUH�PHDVXUHG XVLQJ� D� %,2�5$'� ))6� ���� VSHFWURPHWHU �*HUPDQ\��ZLWK���FPÜ��UHVROXWLRQ�DQG�DFFX� PXODWLRQ� RI� ���� VFDQV�� 7KH� VDPSOHV� ZHUH FRPSDFWV�RI�&+$�FHUDPLFV�DQG�FKLSV�RI�.%U VLQJOH� FU\VWDO� SRZGHUHG� LQ� DQ� DJDWKLF�PRU� WDU�� (OHFWURQ� PLFURVFRSLF� PHDVXUHPHQWV ZHUH� SHUIRUPHG� XVLQJ� D� (6(0�4XDQWD� ��� VFDQQLQJ� PLFURVFRSH� �*HUPDQ\��� 'LODWRPHW� ULF� PHDVXUHPHQWV� ZHUH� FDUULHG� RXW� E\� D ODERUDWRU\� GLODWRPHWHU� DW� WKH� PHDVXUHPHQW DEVROXWH�HUURU�RI������7KH�WHPSHUDWXUH�ZDV FRQWUROOHG� E\� D� FKURPHO�DOXPHO� WKHUPRFRX� SOH� DW� ��&� DFFXUDF\�� 6SHFLILF�ZHLJKW� RI� WKH FHUDPLF�VDPSOHV�ZDV�PHDVXUHG�E\�$UFKLPHG PHWKRG�DQG�DYHUDJHG�IRU����VDPSOHV�LQ�HDFK VHULHV�� 0LFURKDUGQHVV� ZDV� GHWHUPLQHG� E\ 9LFNHUV� PHWKRG� XQGHU� �� 1� PD[LPXP� ORDG DQG� FRPSUHVVLYH� VWUHQJWK�� XVLQJ� D� ODERUD� WRU\�WHVWLQJ�PDFKLQH� 7KH�GLIIUDFWRPHWULF�GDWD�KDYH�VKRZQ�WKDW WKH� VDPSOHV� VLQWHUHG� DW� ���Ü�����&� KDYH WKH� FU\VWDO� VWUXFWXUH� RI� +$� �)LJ������ 7KH GLIIUDFWLRQ�SDWWHUQV�RI�WKH�VDPSOHV�VLQWHUHG DW� ����Ü�����&� UHYHDOHG�� EHVLGH� WKH� PDLQ DSDWLWH� UHIOHFWLRQ�� DQ� DGGLWLRQDO� RQH� ZKLFK LV� XVXDOO\� DVVRFLDWHG� ZLWK� WKH� SULQFLSDO PD[LPXP�RI�FDOFLXP�R[LGH��7KH�ODWWLFH�FRQ� VWDQWV�È� DQG� °� RI� WKH� FRPSDFW�PDWHULDO� LQ� FUHDVH� VWHDGLO\� ZLWK� LQFUHDVLQJ� VLQWHULQJ )LJ����� 'LIIUDFWLRQ� SDWWHUQV� RI� FHUDPLF� VDP� SOHV� VLQWHUHG� DW� WHPSHUDWXUHV� ��&��� ���� ���� ��������������������������������������LQ�FDUE� RQ�GLR[LGH�DWPRVSKHUH��&D2�SKDVH�LV�PDUNHG E\�� �� 0�9�7NDFKHQNR��=�=�=\PDQ���(IIHFW�RI�VLQWHULQJ���� )XQFWLRQDO�PDWHULDOV������������� ��� WHPSHUDWXUH� �)LJ������ ZKHUH� WKH� D� YDOXH� LV VPDOOHU� WKDQ� WKDW� RI� VWRLFKLRPHWULF� +$� DW VLQWHULQJ� WHPSHUDWXUHV� ORZHU� WKDQ� �����& DQG� KLJKHU� DERYH� WKLV� WHPSHUDWXUH� YDOXH� 7KH� F� YDOXH� LQ� WKH�ZLGH� WHPSHUDWXUH� UDQJH ZDV� KLJKHU� WKDQ� LQ� +$�� ,W� LV� GLIILFXOW� WR MXGJH�WKH�QDWXUH�RI�WKHVH�DOWHUDWLRQV�EDVLQJ RQO\�RQ�;�UD\�GDWD��7KHUHIRUH��WKH�,5�VSHF� WUD� RI� WKH� VDPH� VDPSOHV� �)LJ����� PXVW� EH WDNHQ� LQWR� FRQVLGHUDWLRQ�� 7KH� DEVRUSWLRQ EDQGV� RI� FDUERQDWH� LRQV� ����� FPÜ��� ����Ü �����FPÜ��� DUH� SUHVHQW� LQ� DOO� WKH� VSHFWUD� &RQVHTXHQWO\�� WKH� VDPSOHV� DUH� FDUERQDWHG K\GUR[\DSDWLWHV��$V� IRU� WKH�NLQG�RI� VXEVWL� WXWLRQ�� WKH� VDPSOHV� VLQWHUHG� DW� WHPSHUD� WXUHV� ORZHU� WKDQ� �����&� PDQLIHVW� PDLQO\ WKH�EDQGV�RI�%�W\SH�VXEVWLWXWLRQ�ZKLFK�FRU� UHODWHV�ZHOO�ZLWK�WKH�ODWWLFH�FRQVWDQW�YDOXHV �WKH�D�YDOXH�RI�D�&+$� LV� VPDOOHU� WKDQ�WKDW RI� +$�� >��@�� 7KH� VDPSOHV� VLQWHUHG� DW� WHP� SHUDWXUHV� DERYH� �����&� VKRZ� DQ� DGGLWLRQDO DEVRUSWLRQ� DW� ����� FPÜ��� ZKLFK� LV� DVVRFL� DWHG� ZLWK� $� W\SH� VXEVWLWXWLRQ�� 6LPXOWDQH� RXVO\�� WKH� ERWK� ODWWLFH� FRQVWDQWV� LQFUHDVH FRQVLGHUDEO\��WKLV�DOVR�LV�FRQVLVWHQW�ZLWK�WKH NQRZQ� GDWD� >�����@�� 7KH�$� VXEVWLWXWLRQ� EH� FRPHV� SUHGRPLQDQW� DV� FRPSDUHG� WR� WKH� % VLWHV� DW� WKRVH� WHPSHUDWXUHV�� ,W� LV� WR� QRWH WKDW�D�VOLJKW�VSOLWWLQJ�RI�SKRVSKDWH�EDQGV�LQ WKH� ���Ü���� FPÜ�� UDQJH� LV� VHHQ�� L�H�� WKH VKRUW�UDQJH� HQYLURQPHQW� RI� 3 2���� � LRQV� LV GLVWRUWHG�VWURQJO\�E\�WKH�FDUERQDWH�VXEVWLWX� WLRQV�� 7KH� VDPSOHV� DUH� LQ� WKH� VWUDLQHG VWDWHV�� ZKLFK� PD\� UHVXOW� LQ� LPSURYHG� ELR� ORJLFDO� SURSHUWLHV� RI� WKH� LPSODQWV� SUHSDUHG IURP� VXFK� FHUDPLFV� �GXH� WR� WKH� H[SHFWHG LQFUHDVHG� WKH� UHVRUEWLRQ� UDWH��� +HQFH�� VLQ� WHULQJ�WKH�FRPSDFWV�RI�&+$�LQ�WKH�GU\�FDUE� RQ�GLR[LGH�DWPRVSKHUH�LQ�WKH�ZKROH�VWXGLHG WHPSHUDWXUH� UDQJH� UHVXOWV� LQ�$%� IRUPDWLRQ RI�$%�W\SH�FHUDPLFV��ZKHUH�WKH�$�W\SH�VXE� VWLWXWLRQ� H[WHQW� LQFUHDVHV� DV� WKH� VLQWHULQJ WHPSHUDWXUH� ULVHV�� $V� D� FRQVHTXHQFH�� FRP� SDFWV� RI� SUHGRPLQDQW� %�W\SH� &+$� GXULQJ VLQWHULQJ� GHFRPSRVH�ZLWK� IRUPDWLRQ� RI� FDO� FLXP�R[LGH��)LJ����� 7KHVH� YDULDWLRQV� LQ� WKH� SKDVH� FRPSRVL� WLRQ�DIIHFW�WKH�PHFKDQLFDO�FKDUDFWHULVWLFV�RI WKH�FHUDPLFV��7DEOH����$OO�WKH�FKDUDFWHULVWLFV LQFUHDVH� DV� WKH� VLQWHULQJ� WHPSHUDWXUH� ULVHV XS� WR� �����&�� DQG� GURS� VKDUSO\� DERYH� WKH WHPSHUDWXUH��7KH� FHUDPLFV�GHQVLW\� LV����� RI� WKH� WKHRUHWLFDO� YDOXH� IRU� +$� DQG� WKHQ GHFUHDVHV� GRZQ� WR� ��Ü������ 7KH� FRPSUHV� VLYH� VWUHQJWK� DQG� WKH� PLFUR�KDUGQHVV� DOVR GHFUHDVH�ZLWK�UHGXFLQJ�GHQVLW\��6XFK�SHFXOL� DULWLHV� ZHUH� QRW� REVHUYHG� EHIRUH� ZKHQ� VLQ� WHULQJ� &+$� FRPSDFWV� LQ� DLU� >��@� ZKHQ� WKH GHQVLW\�� FRPSUHVVLYH� VWUHQJWK�� DQG� PLFUR� KDUGQHVV� VWHDGLO\� LQFUHDVHG�ZLWK�ULVLQJ�VLQ� WHULQJ� WHPSHUDWXUH��7KLV� LV� GXH� WR� WKH� IDFW )LJ�����'HSHQGHQFH�RI�WKH� ODWWLFH�FRQVWDQWV�D �D�� DQG� F� �E�� RI� FHUDPLFV� RQ� VLQWHULQJ� WHP� SHUDWXUH� )LJ�����,5�VSHFWUD�RI�FHUDPLF�VDPSOHV�VLQWHUHG LQ� FDUERQ� GLR[LGH� DWPRVSKHUH�� 'HVLJQDWLRQV DV�LQ�)LJ���� 0�9�7NDFKHQNR��=�=�=\PDQ���(IIHFW�RI�VLQWHULQJ���� ��� )XQFWLRQDO�PDWHULDOV������������� WKDW�WKH�ILQDO�SURGXFW�LQ�WKH�VWXG\�>��@�ZDV DQ�+$� DQG� LQ� RXU� FDVH�� D� &+$�� 7KXV�� WKH VLQWHULQJ� DWPRVSKHUH� RI� &+$� FRPSDFWV� KDV D�VWDELOL]LQJ�HIIHFW�RQ�WKH�SKDVH�FRPSRVLWLRQ DQG�SURSHUWLHV�RI�WKH�FHUDPLFV� 7KH� SUHVHQFH� RI� WKH� FDUERQ� GLR[LGH� DW� PRVSKHUH� FRQWULEXWHV� WR�ERWK� WKH�PDLQWDLQ� LQJ�RI�WKH� LQLWLDO�FDUERQL]DWLRQ�WR�D�FHUWDLQ GHJUHH� DQG� WKH� VLQWHULQJ� DFFHOHUDWLRQ�� 7KLV LV� FRQILUPHG� E\� WKH� GLODWRPHWULF� PHDVXUH� PHQWV� FRQGXFWHG� GXULQJ� VLQWHULQJ� WKH� FRP� SDFWV�LQ�DLU�DQG�FDUERQ�GLR[LGH��)LJ������7KH FRPSDULVRQ�RI�WKH�VKULQNDJH�FXUYHV�LQ�WKHVH WZR� PHGLD� �WKH� KHDWLQJ� UDWH� LQ� WKH� ERWK FDVHV� LV� ���PLQ�� VKRZV� WKDW� WKH� VKULQNDJH UDWH� LQ� WKH� FDUERQ� GLR[LGH� DWPRVSKHUH� DW WHPSHUDWXUHV� FORVH� WR� �����&� VKDUSO\� LQ� FUHDVHV� DQG� D� VLJQLILFDQW� GHQVLILFDWLRQ� LQ FRPSDFWV� RFFXUUV�� +RZHYHU�� WKH� GHQVLILFD� WLRQ� SURFHVV� LQ� DLU� RFFXUV� LQ� D� ZLGHU� WHP� SHUDWXUH�UDQJH� 7KH� IUDFWXUH� VXUIDFH� PLFURVWUXFWXUH� RI FHUDPLFV� VLQWHUHG� DW� ���Ü�����&� LQ� FDUERQ GLR[LGH� VKRZV� �)LJ���DÜF�� WKDW� DQ� DSSUHFLD� EOH� GHQVLILFDWLRQ� DOUHDG\� RFFXUV� DW� ����&� 7KH�IUDFWXUH�VXUIDFH�PLFURVWUXFWXUH�RI�D�FH� UDPLFV� VLQWHUHG� DW� �����&� LQ� DLU� LV� SUH� VHQWHG� LQ� )LJ���G� IRU� FRPSDULVRQ�� 'HVSLWH WKH�PXFK� KLJKHU� VLQWHULQJ� WHPSHUDWXUH� �E\ ����&�� LW� LV�FOHDUO\�VHHQ�WKDW�VXFK�D�FHUDP� LFV� LV� OHVV� GHQVH� DQG� LWV� VLQWHULQJ� SURFHVV RQO\�VWDUWV�LQ�WKRVH�FRQGLWLRQV� 7KH�DERYH�UHVXOWV�HQULFK�WKH�LQIRUPDWLRQ RQ�WKH�DFWLYDWLRQ�HIIHFW�>����@��7KH�HIIHFW�RI WKH�VKULQNDJH�DFFHOHUDWLRQ�LQ�WKH�FDUERQ�GL� R[LGH� DWPRVSKHUH� PD\� EH� DVVRFLDWHG� ZLWK WKH� IDFW� WKDW� WKH� PDLQ� PDVV� WUDQVSRUW PHFKDQLVP�GXULQJ�WKH�FRPSDFW�GHQVLILFDWLRQ LV�EDVHG�PRVW�OLNHO\�RQ�WKH�VOLGLQJ�WKH�SRZ� GHU� SDUWLFOHV� LQWR� WKH� YRLGV� WKHUHEHWZHHQ� 7KLV� SURFHVV� LV� DFWLYDWHG� EHFDXVH� WKH ERXQGDULHV� RI� DOO� SDUWLFOHV� WDNLQJ� SDUW� LQ WKH�SURFHVV�EHFDPH�UDWKHU�PRELOH��SURYLGLQJ WKXV� D� ORZ�YDOXH� RI� WKH� ERXQGDU\�GLIIXVLYH YLVFRVLW\� DQG�� DV� D� FRQVHTXHQFH�� D� KLJKHU VKULQNDJH�UDWH��7KH�PRELOLW\�RI�WKH�ERXQGD� ULHV�PD\�EH�FDXVHG�E\�WKH�SUHVHQFH�RI�FDUE� RQ�GLR[LGH�DWPRVSKHUH�GXH�WR�IROORZLQJ�FLU� FXPVWDQFHV�� WKH� FDUERQDWH� LRQV� DUH� ZHDNO\ NHSW� E\� WKH� &+$� ODWWLFH� DW� KLJK� WHPSHUD� WXUHV� �VLQWHULQJ�� DQG� FRXOG� HDVLO\� PLJUDWH IURP� %� SRVLWLRQV� WR� $� SRVLWLRQV� DQG� YLFH YHUVD��EHFDXVH�WKH�&2��DWPRVSKHUH�SUHYHQWVWKHLU� UHPRYDO� IURP� WKH� VDPSOH�� &KDRWLF� DO� WHUDWLRQV�LQ�WKH�ODWWLFH�FRQVWDQWV�RFFXU�GXU� LQJ�WKDW�PRWLRQ�ZKLFK�FRXOG�UHVXOW�LQ�VOLJKW VKRUWHQLQJ�DQG�RU�H[SDQVLRQ�RI�WKH�SDUWLFOHV �DW� OHDVW� QHDU� WKHLU� VXUIDFHV��� KDYLQJ� VL]HV RI� D� IHZ�KXQGUHG�RI�QDQRPHWHU� DV� WKRVH�DW WKH� VKULQNDJH� RQVHW�� )LJ���D�� 6XFK� D �EUHDWKLQJ�� SDUWLFOH� LQ� WKH� GLIIXVLYH� VOLS� SLQJ� FRXOG�PRUH� HDVLO\� ILQG� DQ� DSSURSULDWH SRVLWLRQ�LQ�WKH�GHQVLILFDWLRQ�SURFHVV��+HQFH� WKH�VLQWHULQJ�DFFHOHUDWLRQ� LQ�FDUERQ�GLR[LGH DWPRVSKHUH� RFFXUV� PDLQO\� DFFRUGLQJ� WR� WKH JDV�DFWLYDWHG� VKULQNDJH� PHFKDQLVP�� GXULQJ ZKLFK� WKH� PDLQ� PDVV� WUDQVSRUW� RFFXUV� E\ PRYLQJ� D� SDUWLFOH� DV� D� ZKROH�� ,Q� WKH� SURF� HVV�� WKH� FHQWHUV� RI� WKH� VOLSSLQJ� DQG� YLEUDW� LQJ� SDUWLFOHV� PRYH� LQ� DUELWUDU\� GLUHFWLRQV� WKXV� SURYLGLQJ� PD[LPXP� GHQVLILFDWLRQ� RI WKH�HQWLUH�HQVHPEOH� 7KXV�� WKH� IRUPDWLRQ� DQG� SURSHUWLHV� RI SURGXFWV�LQ�WKH�VLQWHULQJ�SURFHVV�RI�FDUERQ� DWH� VXEVWLWXWHG�+$�SRZGHU�FRPSDFWV� LQ� WKH GU\� FDUERQ�GLR[LGH� DWPRVSKHUH� LQ� WKH����Ü �����&� WHPSHUDWXUH� UDQJH� KDYH� EHHQ� VWXG� LHG��$V�D�UHVXOW�� FDUERQDWHG�K\GUR[\DSDWLWH FHUDPLFV� RI� $%� W\SH� VXEVWLWXWLRQ� KDV� EHHQ SUHSDUHG�� 7KH� W\SH� RI� VXEVWLWXWLRQ� LV FKDQJHG�IURP�PDLQO\�%�W\SH�WR�SULPDULO\�$ W\SH�DV�WKH�VLQWHULQJ�WHPSHUDWXUH�LQFUHDVHV� 7KH�%� W\SH�FDUERQDWHG�DSDWLWH� LV�SDUWO\�GH� )LJ�����'LODWRPHWULF�PHDVXUHPHQWV�RI�VKULQN� DJH�RI�FRPSDFWV�LQ�DLU�����DQG�FDUERQ�GLR[LGH ����DWPRVSKHUH� 7DEOH�� 'HQVLW\� �U��� 9LFNHUV� PLFURKDUGQHVV �+9�� DQG�FRPSUHVVLRQ�VWUHQJWK� �W°��RI� FDU�ERQDWHG� K\GUR[\DSDWLWH� FHUDPLFV� VLQWHUHG DW�YDULRXV�WHPSHUDWXUHV �V���& U��J�FP� +9�r������ l3È W°��r������ l3È ��� ����r���� ��� ��� ��� ����r���� ��� ��� ���� ����r���� ��� ��� ���� ����r���� ��� �� ���� ����r���� ��� �� 0�9�7NDFKHQNR��=�=�=\PDQ���(IIHFW�RI�VLQWHULQJ���� )XQFWLRQDO�PDWHULDOV������������� ��� FRPSRVHG�LQWR�D�ELSKDVLF�PL[WXUH�RI�DSDWLWH� FDOFLXP� R[LGH� DW� VLQWHULQJ� WHPSHUDWXUHV DERYH� �����&�� ,Q� WKH� SURFHVV�� WKH� FDUERQ GLR[LGH� VLQWHULQJ� DWPRVSKHUH� VWLPXODWHV� DQ DFWLYDWHG� VKULQNDJH� RI� WKH� FRPSDFWHG� SRZ� GHU�GXH� WR� DFFHOHUDWHG�GLIIXVLYH� VOLSSLQJ�RI SDUWLFOHV�� ZKLFK� UHVXOWV� LQ� D� YHU\� KLJK� H[� WHQW�RI�GHQVLILFDWLRQ�RI�DERXW������DWWDLQ� DEOH�DOUHDG\�DW������&� $FNQRZOHGJPHQW�� 7KH� VWXG\� ZDV� ILQDQ� FLDOO\� VXSSRUWHG� E\� WKH� )XQGDPHQWDO� 5H� VHDUFKHV� 6WDWH� )XQG� RI� WKH� 0LQLVWU\� IRU (GXFDWLRQ� DQG� 6FLHQFH� RI� 8NUDLQH� XQGHU FRQWUDFW� )������������� 7KH� DXWKRUV� WKDQN 3URI�0�(SSOH� �'XLVEXUJ�(VVHQ� 8QLYHUVLW\� *HUPDQ\��IRU�RIIHUHG�SRVVLELOLW\�WR�FRQGXFW WKH�FKHFNLQJ�H[SHULPHQWV� 5HIHUHQFHV � ���6�9�'RUR]KNLQ�� -��0DWHU��6FL��� ���� ���� ��������'2,���������V����������������� � ���/�*�(OOLHV��'�*�$�1HOVRQ��-�'�%�)HDWKHUVWRQH� -��%LRPHG��0DWHU��5HV������������������ � ���0�(�)OHHW�� ;LDR\DQJ� /LX�� -��6ROLG� 6WDWH &KHP������������������� � ���-�%DUUDOHW�� 6�%HVW�� :�%RQILHOG�� -��%LRPHG� 0DWHU��5HV����������������� � ���0�(�)OHHW�� ;L� /LX�� %LRPDWHULDOV�� ���� ��� ������� � ���9�-RNDQRYLF�� '�,]YRQDU�� 0�'�'UDPLFDQLQ� HW DO���-��0DWHU��6FL��0DWHU��0HG������������������ '2,���������V���������������]� � ���-�&�0HUU\��,�5�*LEVRQ��6�0�%HVW��:�%RQILHOG� -��0DWHU��6FL��0DWHU��0HG����������������� � ���,DLQ� 5�*LEVRQ�� :LOOLDP� %RQILHOG�� -��%LRPHG� 0DWHU��5HV������������������ �����-�(�%DUUDOHW��*�-�3�)OHPLQJ��&�&DPSLRQ� ������-�-�+DUULV��-��0DWHU��6FL������������������� ����5�=�� /H*HURV�� 3K'��7KHVLV�� 1HZ� <RUN 8QLYHUVLW\�������� ����=�=\PDQ�� '�5RFKPLVWURY�� ,�,YDQRY�� 0�(SSOH� 0DW��ZLVV�X��:HUNVWRIIWHFK������������������ ����=�=\PDQ�� ,�,YDQRY�� '�5RFKPLVWURY� HW� DO�� %LRPHG��0DWHU��5HV������������������ )LJ�����0LFURVWUXFWXUH�RI�VXUIDFHV�RI�IUDFWXUHG�FHUDPLFV�VLQWHUHG�DW��È������&���E������&���F�������& LQ�FDUERQ�GLR[LGH�DWPRVSKHUH�DQG��G�������&�LQ�DLU� 0�9�7NDFKHQNR��=�=�=\PDQ���(IIHFW�RI�VLQWHULQJ���� ��� )XQFWLRQDO�PDWHULDOV������������� {¹ãÒm��äºm�°¹L}ÈÓÓ«�ÓÈ�ÁLÏÒ�ÓL�mãȰ�Òmº°�L}ȯ­ºÓLϺmÈÓº���L�¯º}°ÒãȹÈ�Ò�Óº��}˯ÈäL}Ò l�{��}È�ËÓ}R��~�~�~ÒäÈÓ �º¯º�º}� }ȯ­ºÓLϺmÈÓº�º� �L�¯º}°ÒãȹÈ�Ò��� º�¯ÒäÈÓº� ¯ËÈ}�L¼ � äLÎ� }ȯ­ºÓÈ�ºä }Èã �L ��È�º¯�ºÁº°Áº¯Óº �}Ò°ãº�º ��{Ò�º�ºmãËÓL�Ï�Ó º�º�¹¯Ë°ºmÈÓL�ϯÈÏ}Ò�°¹L}ÈãÒ°« m�LÓ�˯mÈãL��Ëä¹Ë¯È��¯����Ü�����&���È�亰Á˯L�°�²º�º��Lº}°Ò���m��ãË� ��¹¯Ò�Óº¯äÈã � Óºä���Ò°}����z˯ÈäL}È��º�¯ÒäÈÓÈ����È}Ò®�°¹º°L­��¼�}ȯ­ºÓLϺmÈÓÒä��L�¯º}°ÒãȹÈ�Ò�ºä k{��Ò¹��� {Ò�� }ȯ­ºÓLÏÈ�L�� ÏäLÓ ¼� °«� mL�� ¹Ë¯ËmÈÎÓº� {��Ò¹�� ¹¯Ò� mL�Óº°Óº� ÓÒÏ }Ò² �Ëä¹Ë¯È��¯È²� �º� ¹Ë¯ËmÈÎÓº� k��Ò¹�� Û� ¹¯Ò� mÒ°º}Ò²� �Ëä¹Ë¯È��¯È²� °¹L}ÈÓÓ«�� {Ò�Ë �����&�mL�­�mȼ� °«��Ȱ�}ºmÒ®�¯ºÏ¹È��ȹÈ�Ò���{��Ò¹���È�mÒ�LãËÓÓ«�º}Ò°��}Èã �L ���¯Ò � ºä�� ¹º¯Ò°�L°� � }˯ÈäL}Ò� ϯº°�ȼ� �È� ¯LÏ}º� ¹È�È � � ��� ä˲ÈÓL�ÓL� mãȰ�Òmº°�L�� �¯Ò �Ëä¹Ë¯È��¯È²� ÓÒÎ�Ë� �����&� È�亰Á˯È� �Lº}°Ò��� m��ãË� � °¹¯Ò«¼� È}�ÒmºmÈÓL®� �°È��L ¹¯Ë°ºmº}� ÏÈm�«}Ò� ¹¯Ò°}º¯ËÓÓ � �ÒÁ�ÏL®Óº�� äL�¯È�L�� �Ȱ�ÒÓº}� ¹º¯º�}��� ~º}¯ËäÈ�� �Ë ¹¯Òmº�Ò� ��º��º°«�ÓËÓÓ«�mÒ°º}º���Lã Óº°�L�}˯ÈäL}Ò��a������mL���˺¯Ë�Ò�Óº�º�ÏÓÈ�ËÓ� Ó«��k��¹¯Ò��Ëä¹Ë¯È��¯L������&� 0�9�7NDFKHQNR��=�=�=\PDQ���(IIHFW�RI�VLQWHULQJ���� )XQFWLRQDO�PDWHULDOV������������� ���