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Microbial corrosion (MIC) ndi vuto lalikulu m'mafakitale ambiri, chifukwa litha kubweretsa kuwonongeka kwakukulu kwachuma.Super duplex stainless steel 2707 (2707 HDSS) imagwiritsidwa ntchito m'malo am'madzi chifukwa cha kukana kwake kwamankhwala.Komabe, kukana kwake ku MIC sikunawonetsedwe moyesera.Kafukufukuyu adawunika machitidwe a MIC 2707 HDSS oyambitsidwa ndi mabakiteriya amadzimadzi a Pseudomonas aeruginosa.Kusanthula kwa Electrochemical kunawonetsa kuti pamaso pa Pseudomonas aeruginosa biofilm mu sing'anga ya 2216E, kusintha kwabwino pakutha kwa dzimbiri komanso kuwonjezeka kwa kachulukidwe ka dzimbiri kumachitika.Kuwunika kwa X-ray photoelectron spectroscopy (XPS) kunawonetsa kuchepa kwa Cr zomwe zili pamtunda wa chitsanzo pansi pa biofilm.Kuwunika kowonekera kwa maenjewo kunawonetsa kuti P. aeruginosa biofilm idapanga dzenje lozama kwambiri la 0.69 µm mkati mwa masiku 14 akuyalitsa.Ngakhale izi ndizochepa, zimasonyeza kuti 2707 HDSS sichitetezedwa kwathunthu ndi MIC ya P. aeruginosa biofilms.
Zitsulo zosapanga dzimbiri za Duplex (DSS) zimagwiritsidwa ntchito kwambiri m'mafakitale osiyanasiyana chifukwa cha kuphatikiza kwabwino kwamakina ndi kukana dzimbiri1,2.Komabe, kubowola kwapadera kumachitikabe ndipo kumakhudza kukhulupirika kwazitsulo3,4.DSS sichigonjetsedwa ndi tizilombo toyambitsa matenda (MIC) 5,6.Ngakhale kuti pali mitundu yosiyanasiyana ya ntchito za DSS, pali malo omwe kukana kwa dzimbiri kwa DSS sikukwanira kugwiritsidwa ntchito kwa nthawi yayitali.Izi zikutanthawuza kuti zipangizo zokwera mtengo zokhala ndi kukana kwa dzimbiri zimafunika.Jeon et al7 adapeza kuti ngakhale zitsulo zosapanga dzimbiri zosapanga dzimbiri (SDSS) zili ndi malire pokana dzimbiri.Chifukwa chake, nthawi zina, zitsulo zosapanga dzimbiri zosapanga dzimbiri (HDSS) zokhala ndi dzimbiri zapamwamba zimafunikira.Izi zidapangitsa kuti ma HDSS apangidwe kwambiri.
Kukana kwa dzimbiri DSS kumadalira chiŵerengero cha magawo a alpha ndi gamma ndi kutha m'madera a Cr, Mo ndi W 8, 9, 10 moyandikana ndi gawo lachiwiri.HDSS ili ndi zambiri za Cr, Mo ndi N11, chifukwa chake ili ndi kukana kwa dzimbiri komanso mtengo wapamwamba (45-50) wa nambala yofananira yokana (PREN) yotsimikiziridwa ndi wt.% Cr + 3.3 (wt.% Mo + 0.5 wt. .%W) + 16% wt.N12.Kukana kwake kwa dzimbiri kumadalira kapangidwe koyenera komwe kamakhala ndi magawo pafupifupi 50% ferritic (α) ndi 50% austenitic (γ) magawo.HDSS ili ndi zida zabwino zamakina komanso kukana kwambiri kwa dzimbiri la chloride.Kukhazikika kwa dzimbiri kumakulitsa kugwiritsa ntchito HDSS m'malo owopsa a chloride monga madera am'madzi.
Ma MIC ndi vuto lalikulu m'mafakitale ambiri monga mafakitale amafuta ndi gasi ndi madzi14.MIC imapanga 20% ya zowonongeka zonse15.MIC ndi corrosion ya bioelectrochemical yomwe imatha kuwonedwa m'malo ambiri.Ma biofilms omwe amapanga pazitsulo amasintha ma electrochemical zinthu, motero amakhudza njira ya dzimbiri.Anthu ambiri amakhulupirira kuti MIC corrosion imayamba chifukwa cha biofilms.Tizilombo tating'onoting'ono timadya zitsulo kuti tipeze mphamvu zomwe zimafunikira kuti tipulumuke17.Kafukufuku waposachedwa wa MIC wasonyeza kuti EET (extracellular electron transfer) ndiyomwe imalepheretsa kuchuluka kwa MIC yoyambitsidwa ndi ma electrogenic microorganisms.Zhang et al.18 idawonetsa kuti ma electron intermediaries amafulumizitsa kusamutsa ma electron pakati pa maselo a Desulfovibrio sessificans ndi 304 zitsulo zosapanga dzimbiri, zomwe zimapangitsa kuti MIC iwonongeke kwambiri.Anning ndi al.19 ndi Wenzlaff et al.20 awonetsa kuti ma biofilms a corrosive sulfate-reducing bacteria (SRBs) amatha kuyamwa ma elekitironi mwachindunji ku magawo azitsulo, zomwe zimapangitsa kuti pakhale pitting kwambiri.
DSS imadziwika kuti imakhudzidwa ndi MIC muzofalitsa zomwe zili ndi SRBs, mabakiteriya ochepetsa chitsulo (IRBs), etc. 21.Mabakiteriyawa amayambitsa kupindika komwe kumapezeka pamwamba pa DSS pansi pa biofilms22,23.Mosiyana ndi DSS, HDSS24 MIC sichidziwika bwino.
Pseudomonas aeruginosa ndi kachilombo ka Gram-negative, motile, ngati ndodo yomwe imafalitsidwa kwambiri mu chilengedwe25.Pseudomonas aeruginosa ndi gulu lalikulu la tizilombo tating'onoting'ono m'madzi am'madzi, zomwe zimapangitsa kuchuluka kwa MIC.Pseudomonas amatenga nawo mbali pakupanga dzimbiri ndipo amadziwika kuti ndi mpainiya wapaintaneti panthawi yopanga biofilm.Mahat et al.28 ndi Yuan et al.29 idawonetsa kuti Pseudomonas aeruginosa imakonda kukulitsa chiwopsezo cha chitsulo chochepa komanso ma aloyi m'malo am'madzi.
Cholinga chachikulu cha ntchitoyi chinali kufufuza zinthu za MIC 2707 HDSS zomwe zimayambitsidwa ndi mabakiteriya a m'madzi a Pseudomonas aeruginosa pogwiritsa ntchito njira za electrochemical, njira zowunikira pamwamba ndi kusanthula kwazinthu zowonongeka.Maphunziro a Electrochemical, kuphatikiza kuthekera kotseguka (OCP), liniya polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), ndi polarization yomwe ingakhale yosinthika, adachitidwa kuti aphunzire za MIC 2707 HDSS.Energy dispersive spectrometric analysis (EDS) idachitika kuti izindikire zinthu zamakemikolo pamalo ochita dzimbiri.Kuphatikiza apo, X-ray photoelectron spectroscopy (XPS) idagwiritsidwa ntchito kudziwa kukhazikika kwa filimu ya okusayidi motsogozedwa ndi malo am'madzi okhala ndi Pseudomonas aeruginosa.Kuzama kwa maenjewo kudayezedwa pogwiritsa ntchito makina oonera microscope (CLSM) a confocal laser.
Gulu 1 likuwonetsa kapangidwe kake ka 2707 HDSS.Table 2 ikuwonetsa kuti 2707 HDSS ili ndi makina abwino kwambiri okhala ndi mphamvu zokolola za 650 MPa.Pa mkuyu.1 imasonyeza kuwala kwa microstructure ya yankho la kutentha kwa 2707 HDSS.Mu microstructure munali pafupifupi 50% austenite ndi 50% ferrite magawo, elongated magulu austenite ndi ferrite magawo popanda yachiwiri magawo amaoneka.
Pa mkuyu.2a ikuwonetsa kuthekera kwa dera lotseguka (Eocp) motsutsana ndi nthawi yowonekera kwa 2707 HDSS mu 2216E abiotic medium ndi msuzi wa P. aeruginosa kwa masiku 14 pa 37 ° C.Zikuwonetsa kuti kusintha kwakukulu komanso kofunikira kwambiri mu Eocp kumachitika mkati mwa maola 24 oyamba.Makhalidwe a Eocp muzochitika zonsezi adafika pa -145 mV (poyerekeza ndi SCE) mozungulira 16 h ndiyeno adatsika kwambiri, kufika -477 mV (poyerekeza ndi SCE) ndi -236 mV (poyerekeza ndi SCE) pa zitsanzo za abiotic.ndi P Pseudomonas aeruginosa makuponi, motsatana).Pambuyo pa maola 24, mtengo wa Eocp 2707 HDSS wa P. aeruginosa unali wokhazikika pa -228 mV (poyerekeza ndi SCE), pamene mtengo wofanana wa zitsanzo zomwe sizinali zamoyo zinali pafupifupi -442 mV (poyerekeza ndi SCE).Eocp pamaso pa P. aeruginosa anali otsika kwambiri.
Kuphunzira kwa Electrochemical kwa zitsanzo za 2707 HDSS mu abiotic medium ndi Pseudomonas aeruginosa msuzi pa 37 ° C:
(a) Eocp ngati ntchito ya nthawi yowonekera, (b) ma curve a polarization pa tsiku la 14, (c) Rp monga ntchito ya nthawi yowonekera, ndi (d) icorr monga ntchito ya nthawi yowonekera.
Table 3 ikuwonetsa magawo a electrochemical corrosion a 2707 HDSS zitsanzo zowululidwa ndi abiotic ndi Pseudomonas aeruginosa zojambulidwa m'masiku 14.Ma tangents a anode ndi cathode curves anali extrapolated kuti apeze mphambano yopatsa corrosion current density (icorr), corrosion potential (Ecorr) ndi Tafel slope (βα ndi βc) malinga ndi njira zokhazikika30,31.
Monga momwe tawonetsera mkuyu.2b, kusuntha kwapamwamba kwa P. aeruginosa curve kunapangitsa kuwonjezeka kwa Ecorr poyerekeza ndi ma curve abiotic.Mtengo wa icorr, womwe umayenderana ndi kuchuluka kwa dzimbiri, udakwera kufika pa 0.328 µA cm-2 mu zitsanzo za Pseudomonas aeruginosa, zomwe ndi zazikulu kuwirikiza kanayi kuposa zomwe sizinali zamoyo (0.087 µA cm-2).
LPR ndi njira yachikale yosawononga ma elekitiromu yamagetsi yowunikira mwachangu dzimbiri.Yagwiritsidwanso ntchito pophunzira MIC32.Pa mkuyu.2c ikuwonetsa kukana kwa polarization (Rp) ngati ntchito ya nthawi yowonekera.Mtengo wokwera wa Rp umatanthauza kuchepa kwa dzimbiri.Mkati mwa maola 24 oyambirira, Rp 2707 HDSS inafika pachimake pa 1955 kΩ cm2 pa zitsanzo za abiotic ndi 1429 kΩ cm2 pa zitsanzo za Pseudomonas aeruginosa.Chithunzi 2c chikuwonetsanso kuti mtengo wa Rp unatsika mofulumira pambuyo pa tsiku limodzi ndipo umakhalabe wosasintha m'masiku otsatirawa a 13.Mtengo wa Rp wa chitsanzo cha Pseudomonas aeruginosa ndi pafupifupi 40 kΩ cm2, womwe ndi wotsika kwambiri kuposa mtengo wa 450 kΩ cm2 wa zitsanzo zomwe sizinali zamoyo.
Mtengo wa icorr umalingana ndi kuchuluka kwa dzimbiri kofanana.Mtengo wake ukhoza kuwerengedwa kuchokera ku Stern-Giri equation:
Malinga ndi Zoe et al.33, mtengo wamba wa Tafel otsetsereka B mu ntchitoyi adatengedwa kukhala 26 mV/dec.Chithunzi 2d chikuwonetsa kuti icorr ya chitsanzo chosakhala chamoyo cha 2707 chinakhalabe chokhazikika, pamene chitsanzo cha P. aeruginosa chinasintha kwambiri pambuyo pa maola 24 oyambirira.Miyezo ya icorr ya zitsanzo za P. aeruginosa zinali zochulukira kwambiri kuposa zomwe sizimawongolera zachilengedwe.Izi zikugwirizana ndi zotsatira za polarization resistance.
EIS ndi njira ina yosawononga yomwe imagwiritsidwa ntchito powonetsa ma electrochemical reaction pamalo owonongeka.Impedance spectra ndi kuwerengetsera capacitance mitengo ya zitsanzo zovumbulutsidwa ndi abiotic chilengedwe ndi Pseudomonas aeruginosa yankho, kungokhala chete filimu / biofilm kukana Rb kupangidwa pa sampuli pamwamba, kusamutsa kukana Rct, magetsi awiri wosanjikiza capacitance Cdl (EDL) ndi nthawi zonse QCPE Phase magawo. (CPE).Magawo awa adawunikidwanso ndikuyika deta pogwiritsa ntchito chitsanzo chofanana ndi dera (EEC).
Pa mkuyu.3 ikuwonetsa ziwembu za Nyquist (a ndi b) ndi ziwembu za Bode (a' ndi b') za zitsanzo 2707 za HDSS mu abiotic media ndi msuzi wa P. aeruginosa nthawi zosiyanasiyana zokulitsira.Kutalika kwa mphete ya Nyquist kumachepa pamaso pa Pseudomonas aeruginosa.Chiwembu cha Bode (mkuyu 3b ') chikuwonetsa kuwonjezeka kwa impedance yonse.Zambiri zokhudzana ndi nthawi yopumula nthawi zonse zitha kupezeka kuchokera ku phase maxima.Pa mkuyu.4 ikuwonetsa mawonekedwe akuthupi otengera monolayer (a) ndi bilayer (b) ndi ma EEC ofanana.CPE imayambitsidwa mu chitsanzo cha EEC.Kuloledwa kwake ndi kulepheretsa kwake kumawonetsedwa motere:
Zitsanzo ziwiri zakuthupi ndi mabwalo ofanana kuti agwirizane ndi mawonekedwe a 2707 HDSS:
kumene Y0 ndi mtengo wa KPI, j ndi nambala yongoganizira kapena (-1) 1/2, ω ndi ma frequency aang'ono, n ndi KPI mphamvu index zosakwana one35.Kusintha kwa kukana kwa ndalama (ie 1/Rct) kumafanana ndi kuchuluka kwa dzimbiri.Rct yaying'ono, imakwera kuchuluka kwa dzimbiri27.Pambuyo pa masiku 14 a incubation, zitsanzo za Rct ya Pseudomonas aeruginosa zinafika 32 kΩ cm2, zomwe ndi zochepa kwambiri kuposa 489 kΩ cm2 ya zitsanzo zomwe sizinali zamoyo (Table 4).
Zithunzi za CLSM ndi zithunzi za SEM mu Chithunzi 5 zikuwonetseratu kuti chophimba cha biofilm pamwamba pa HDSS chitsanzo 2707 pambuyo pa masiku 7 ndi wandiweyani.Komabe, patatha masiku 14, kufalitsa kwa biofilm kunali kocheperako ndipo maselo ena akufa adawonekera.Gulu 5 likuwonetsa makulidwe a biofilm pa zitsanzo 2707 HDSS mutakumana ndi P. aeruginosa kwa masiku 7 ndi 14.Kuchuluka kwa biofilm kunasintha kuchoka pa 23.4 µm patatha masiku 7 kufika pa 18.9 µm patatha masiku 14.Avereji makulidwe a biofilm adatsimikiziranso izi.Inatsika kuchokera pa 22.2 ± 0.7 μm patatha masiku 7 kufika pa 17.8 ± 1.0 μm patatha masiku 14.
(a) Chithunzi cha 3-D CLSM pamasiku 7, (b) chithunzi cha 3-D CLSM pamasiku 14, (c) Chithunzi cha SEM pamasiku 7, ndi (d) chithunzi cha SEM pamasiku 14.
EMF idavumbulutsa zinthu zamakemikolo mu biofilms ndi zinthu zowononga pazitsanzo zowululidwa ndi P. aeruginosa kwa masiku 14.Pa mkuyu.Chithunzi 6 chikuwonetsa kuti zomwe zili mu C, N, O, ndi P mu biofilms ndi zinthu zowonongeka ndizokwera kwambiri kuposa zitsulo zoyera, chifukwa zinthuzi zimagwirizanitsidwa ndi biofilms ndi metabolites yawo.Tizilombo tating'onoting'ono timangofunika kuchuluka kwa chromium ndi ayironi.Miyezo yapamwamba ya Cr ndi Fe mu biofilm ndi zinthu zowonongeka pamwamba pa zitsanzo zimasonyeza kuti matrix achitsulo ataya zinthu chifukwa cha dzimbiri.
Pambuyo pa masiku 14, maenje okhala ndi P. aeruginosa adawonedwa mkatikati mwa 2216E.Pamaso makulitsidwe, padziko zitsanzo anali yosalala ndi chilema wopanda (mkuyu. 7a).Pambuyo poyambitsa ndi kuchotsedwa kwa biofilm ndi zinthu zowonongeka, maenje akuya kwambiri pamwamba pa zitsanzo adayesedwa pogwiritsa ntchito CLSM, monga momwe tawonetsera mkuyu 7b ndi c.Palibe dzenje lodziwikiratu lomwe linapezeka pamwamba pa zowongolera zomwe sizinali zamoyo (kuzama kwa dzenje 0.02 µm).Kuzama kwakukulu kwa dzenje komwe kunayambitsidwa ndi P. aeruginosa kunali 0.52 µm pamasiku 7 ndi 0.69 µm pamasiku 14, kutengera kuzama kwakukulu kwa dzenje kuchokera ku zitsanzo za 3 (kuzama kwa dzenje 10 kunasankhidwa pachitsanzo chilichonse).Kupambana kwa 0.42 ± 0.12 µm ndi 0.52 ± 0.15 µm, motsatana (Table 5).Izi zakuya zakuya ndizochepa koma ndizofunikira.
(a) asanalowe m'thupi, (b) masiku 14 m'malo okhala ndi abiotic, ndi (c) masiku 14 mu msuzi wa Pseudomonas aeruginosa.
Pa mkuyu.Table 8 ikuwonetsa mawonekedwe a XPS a mawonekedwe osiyanasiyana a zitsanzo, ndipo mawonekedwe a mankhwala omwe amawunikidwa pa malo aliwonse akufotokozedwa mwachidule mu Table 6. otsika kwambiri kuposa omwe amawongolera omwe si achilengedwe.(zitsanzo C ndi D).Kwa chitsanzo cha P. aeruginosa, ma curve owonera pamlingo wa Cr 2p nucleus adayikidwa pazigawo zinayi zapamwamba zomwe zimakhala ndi mphamvu zomangirira (BE) za 574.4, 576.6, 578.3 ndi 586.8 eV, zomwe zitha kukhala za Cr, CrO3O3, CrO3, CrO3, CrO3, CrO3 .ndi Cr(OH)3, motsatana (mkuyu 9a ndi b).Kwa zitsanzo zosakhala zamoyo, mawonekedwe a mulingo waukulu wa Cr 2p ali ndi nsonga zazikulu ziwiri za Cr (573.80 eV ya BE) ndi Cr2O3 (575.90 eV ya BE) mu Fig.9c ndi d.Kusiyana kochititsa chidwi kwambiri pakati pa zitsanzo za abiotic ndi zitsanzo za P. aeruginosa kunali kukhalapo kwa Cr6+ ndi gawo lapamwamba la Cr(OH)3 (BE 586.8 eV) pansi pa biofilm.
Mawonekedwe otakata a XPS a pamwamba pa zitsanzo 2707 HDSS m'ma media awiri ndi masiku 7 ndi 14, motsatana.
(a) Kukumana ndi P. aeruginosa kwa masiku 7, (b) Kukumana ndi P. aeruginosa masiku 14, (c) masiku 7 m’malo okhala ndi abiotic, ndi (d) masiku 14 m’malo opezeka m’chilengedwe.
HDSS imawonetsa kukana kwambiri kwa dzimbiri m'malo ambiri.Kim et al.2 adanena kuti HDSS UNS S32707 idadziwika kuti ndi DSS yosakanikirana kwambiri ndi PREN yoposa 45. Mtengo wa PREN wa chitsanzo cha 2707 HDSS mu ntchitoyi unali 49. Izi ndi chifukwa cha chromium yapamwamba komanso zomwe zili pamwambazi. molybdenum ndi faifi tambala, zomwe zimathandiza m'malo acidic.ndi malo okhala ndi chloride wambiri.Kuphatikiza apo, kapangidwe koyenera komanso kachipangizo kakang'ono kopanda chilema ndizothandiza pakukhazikika kwamapangidwe komanso kukana dzimbiri.Komabe, ngakhale kuti amatsutsa kwambiri mankhwala, deta yoyesera mu ntchitoyi imasonyeza kuti 2707 HDSS sichitetezedwa kwathunthu ndi P. aeruginosa biofilm MICs.
Zotsatira za electrochemical zasonyeza kuti kuchuluka kwa dzimbiri kwa 2707 HDSS mu msuzi wa P. aeruginosa kunakula kwambiri pambuyo pa masiku 14 poyerekeza ndi malo omwe si achilengedwe.Mu chithunzi 2a, kuchepa kwa Eocp kunawonedwa mu abiotic sing'anga ndi P. aeruginosa msuzi m'maola 24 oyamba.Pambuyo pake, biofilm imaphimba pamwamba pa chitsanzo, ndipo Eocp imakhala yokhazikika36.Komabe, mulingo wa Eocp wachilengedwe unali wapamwamba kwambiri kuposa mulingo wa Eocp womwe si wachilengedwe.Pali zifukwa zokhulupirira kuti kusiyana kumeneku kumagwirizana ndi mapangidwe a P. aeruginosa biofilms.Pa mkuyu.2d pamaso pa P. aeruginosa, mtengo wa icorr 2707 HDSS unafika pa 0.627 μA cm-2, yomwe ndi dongosolo la kukula kwakukulu kuposa la abiotic control (0.063 μA cm-2), yomwe inali yogwirizana ndi mtengo wa Rct woyezedwa ndi EIS.M'masiku angapo oyambilira, zosokoneza mu msuzi wa P. aeruginosa zidakula chifukwa cholumikizidwa ndi ma cell a P. aeruginosa ndikupanga ma biofilms.Komabe, pamene biofilm ikuphimba kwathunthu sampuli pamwamba, impedance imachepa.Wosanjikiza woteteza amawukiridwa makamaka chifukwa cha mapangidwe a biofilms ndi biofilm metabolites.Chifukwa chake, kukana kwa dzimbiri kunachepa pakapita nthawi ndipo kulumikizidwa kwa P. aeruginosa kunayambitsa dzimbiri mdera lanu.Zomwe zimachitika m'malo abiotic zinali zosiyana.Kukaniza kwa dzimbiri kwa kuwongolera kosakhala kwachilengedwe kunali kwakukulu kwambiri kuposa mtengo wofananira wa zitsanzo zomwe zimawonekera ku msuzi wa P. aeruginosa.Kuonjezera apo, pazigawo za abiotic, mtengo wa Rct 2707 HDSS unafika 489 kΩ cm2 pa tsiku la 14, lomwe ndi lokwera ka 15 kuposa mtengo wa Rct (32 kΩ cm2) pamaso pa P. aeruginosa.Chifukwa chake, 2707 HDSS ili ndi kukana kwa dzimbiri kwabwino kwambiri m'malo osabala, koma osagonjetsedwa ndi ma MIC ochokera ku P. aeruginosa biofilms.
Zotsatirazi zitha kuwonedwanso kuchokera ku ma curve polarization mu Mkuyu.2b .Anodic nthambi yakhala ikugwirizanitsidwa ndi Pseudomonas aeruginosa biofilm mapangidwe ndi zochitika zazitsulo za okosijeni.Pankhaniyi, cathodic anachita ndi kuchepetsa mpweya.Kukhalapo kwa P. aeruginosa kumawonjezera kuchuluka kwa dzimbiri panopa, za dongosolo la ukulu kuposa mu ulamuliro abiotic.Izi zikusonyeza kuti P. aeruginosa biofilm imapangitsa kuti 2707 HDSS iwonongeke.Yuan et al.29 adapeza kuti kachulukidwe kakachulukidwe ka Cu-Ni 70/30 kachulukidwe ka aloyi kamawonjezeka chifukwa cha P. aeruginosa biofilm.Izi zitha kukhala chifukwa cha biocatalysis ya kuchepetsa mpweya ndi Pseudomonas aeruginosa biofilms.Izi zitha kufotokozeranso za MIC 2707 HDSS pantchitoyi.Pakhoza kukhalanso mpweya wochepa pansi pa aerobic biofilms.Choncho, kukana kubwezeretsanso zitsulo pamwamba ndi mpweya kungakhale chinthu chothandizira MIC pa ntchitoyi.
Dickinson ndi al.38 inanena kuti kuchuluka kwa machitidwe amankhwala ndi ma electrochemical amatha kukhudzidwa mwachindunji ndi kagayidwe kachakudya ka mabakiteriya a sessile pazitsanzo komanso mtundu wazinthu zowononga.Monga momwe tawonetsera pa Chithunzi 5 ndi Table 5, chiwerengero cha maselo ndi biofilm makulidwe achepa pambuyo pa masiku 14.Izi zitha kufotokozedwa momveka bwino chifukwa patatha masiku 14, ma cell ambiri omwe amakhala pamtunda wa 2707 HDSS adamwalira chifukwa cha kuchepa kwa michere mu sing'anga ya 2216E kapena kutulutsa ayoni achitsulo chowopsa kuchokera ku 2707 HDSS matrix.Izi ndizochepa zoyeserera zamagulu.
Mu ntchitoyi, P. aeruginosa biofilm inathandiza kuti Cr ndi Fe awonongeke m'deralo pansi pa biofilm pamwamba pa 2707 HDSS (Mkuyu 6).Table 6 ikuwonetsa kuchepa kwa Fe ndi Cr mu chitsanzo cha D poyerekeza ndi chitsanzo C, kusonyeza kuti Fe ndi Cr zosungunuka zomwe zinayambitsidwa ndi P. aeruginosa biofilm zinapitirira kwa masiku oyambirira a 7.Chilengedwe cha 2216E chimagwiritsidwa ntchito kutengera chilengedwe cha m'madzi.Lili ndi 17700 ppm Cl-, yomwe ikufanana ndi zomwe zili m'madzi am'nyanja achilengedwe.Kukhalapo kwa 17700 ppm Cl- kunali chifukwa chachikulu cha kuchepa kwa Cr mu 7- ndi 14-day abiotic zitsanzo zofufuzidwa ndi XPS.Poyerekeza ndi zitsanzo za P. aeruginosa, kusungunuka kwa Cr mu zitsanzo za abiotic kunali kochepa kwambiri chifukwa cha kukana kwamphamvu kwa 2707 HDSS ku chlorine pansi pazikhalidwe za abiotic.Pa mkuyu.9 ikuwonetsa kukhalapo kwa Cr6 + mufilimuyi.Ikhoza kukhudzidwa ndi kuchotsedwa kwa chromium kuchokera kuzitsulo za P. aeruginosa biofilms, monga momwe Chen ndi Clayton anafotokozera.
Chifukwa cha kukula kwa bakiteriya, pH ya sing'anga isanayambe kapena itatha kulima inali 7.4 ndi 8.2, motsatana.Choncho, pansi pa P. aeruginosa biofilm, organic acid corrosion sizingatheke kuti athandize ntchitoyi chifukwa cha pH yochuluka kwambiri.pH ya sing'anga yoyang'anira zachilengedwe sinasinthe kwambiri (kuchokera pa 7.4 mpaka 7.5 yomaliza) mkati mwa masiku 14 oyesa.Kuwonjezeka kwa pH m'kati mwa inoculation pambuyo poyamwitsa kunagwirizanitsidwa ndi ntchito ya kagayidwe kachakudya ya P. aeruginosa ndipo inapezeka kuti imakhala ndi zotsatira zofanana pa pH popanda mizere yoyesera.
Monga momwe zasonyezedwera mu Chithunzi 7, kuzama kwakukulu kwa dzenje komwe kunayambitsidwa ndi P. aeruginosa biofilm kunali 0.69 µm, komwe kuli kokulirapo kuposa komwe kumapangidwira (0.02 µm).Izi zikugwirizana ndi deta ya electrochemical yomwe yafotokozedwa pamwambapa.Kuzama kwa dzenje la 0.69 µm ndikocheperako kuwirikiza kakhumi kuposa mtengo wa 9.5 µm womwe udanenedwa pa 2205 DSS pansi pamikhalidwe yomweyi.Izi zikuwonetsa kuti 2707 HDSS ikuwonetsa kukana bwino kwa MICs kuposa 2205 DSS.Izi siziyenera kudabwitsidwa popeza 2707 HDSS ili ndi milingo yayikulu ya Cr yomwe imapereka mwayi wotalikirapo, wovuta kwambiri kuyimitsa P. aeruginosa, komanso chifukwa cha kapangidwe kake koyenera kopanda mvula yachiwiri yovulaza imayambitsa kupindika.
Pomaliza, maenje a MIC adapezeka pamtunda wa 2707 HDSS mu msuzi wa P. aeruginosa poyerekeza ndi maenje osafunikira m'malo abiotic.Ntchitoyi ikuwonetsa kuti 2707 HDSS ili ndi kukana bwino kwa MIC kuposa 2205 DSS, koma sikutetezedwa kwathunthu ndi MIC chifukwa cha P. aeruginosa biofilm.Zotsatirazi zimathandizira pakusankha zitsulo zosapanga dzimbiri zoyenera komanso moyo wokhala ndi moyo wam'madzi.
Kuponi kwa 2707 HDSS yoperekedwa ndi Northeastern University (NEU) School of Metallurgy ku Shenyang, China.Zolemba zoyambirira za 2707 HDSS zikuwonetsedwa mu Table 1, yomwe idawunikidwa ndi NEU Materials Analysis and Testing Department.Zitsanzo zonse zimathandizidwa kuti zikhale zolimba pa 1180 ° C kwa ola limodzi.Asanayezetse dzimbiri, 2707 HDSS yooneka ngati ndalama yokhala ndi malo otseguka pamwamba pa 1 cm2 idapukutidwa mpaka grit 2000 ndi sandpaper ya silicon carbide ndikupukutidwa ndi 0.05 µm Al2O3 powder slurry.M'mbali ndi pansi zimatetezedwa ndi utoto wa inert.Pambuyo kuyanika, zitsanzozo zimatsukidwa ndi madzi osabala a deionized ndi chosawilitsidwa ndi 75% (v/v) ethanol kwa 0,5 h.Kenako amawumitsidwa ndi kuwala kwa ultraviolet (UV) kwa maola 0.5 musanagwiritse ntchito.
Marine Pseudomonas aeruginosa strain MCCC 1A00099 idagulidwa kuchokera ku Xiamen Marine Culture Collection Center (MCCC), China.Pseudomonas aeruginosa anakula pansi pa aerobic mikhalidwe pa 37 ° C. mu 250 ml flasks ndi 500 ml galasi electrochemical maselo ntchito Marine 2216E madzi sing'anga (Qingdao Hope Biotechnology Co., Ltd., Qingdao, China).Pakatikati pake chotsitsa yisiti ndi 0,1 iron citrate.Autoclave pa 121 ° C kwa mphindi 20 isanafike inoculation.Werengani ma cell a sessile ndi planktonic okhala ndi hemocytometer pansi pa maikulosikopu yopepuka pakukula kwa 400x.Kuchuluka koyambirira kwa planktonic Pseudomonas aeruginosa mwamsanga pambuyo pa inoculation kunali pafupifupi 106 maselo / ml.
Mayeso a electrochemical adachitika mu cell yagalasi yama electrode atatu okhala ndi sing'anga 500 ml.The platinamu pepala ndi zimalimbikitsa calomel elekitirodi (SAE) anali olumikizidwa kwa riyakitala kudzera Luggin capillaries wodzazidwa ndi mchere milatho, amene anali ngati kauntala ndi maelekitirodi zolozera, motero.Popanga maelekitirodi ogwira ntchito, waya wamkuwa wopangidwa ndi rubberized adamangiriridwa ku chitsanzo chilichonse ndikuphimba ndi utomoni wa epoxy, ndikusiya pafupifupi 1 cm2 ya malo osatetezedwa a elekitirodi yogwira ntchito mbali imodzi.Pamiyeso yama electrochemical, zitsanzozo zinayikidwa mu sing'anga ya 2216E ndikusungidwa kutentha kosalekeza (37 ° C) mu osamba madzi.OCP, LPR, EIS ndi data yomwe ingakhalepo polarization idayezedwa pogwiritsa ntchito Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA).Mayesero a LPR adalembedwa pa scan scan ya 0.125 mV s-1 mumtundu wa -5 mpaka 5 mV ndi Eocp ndi chitsanzo cha 1 Hz.EIS inkachitika ndi mafunde a sine pa ma frequency osiyanasiyana a 0.01 mpaka 10,000 Hz pogwiritsa ntchito mphamvu yamagetsi ya 5 mV pa Eocp yokhazikika.Asanayambe kuseseratu, ma electrode anali osagwira ntchito mpaka mtengo wokhazikika wa mphamvu zowonongeka zaulere unafikiridwa.Ma curve polarization adayesedwa kuchokera ku -0.2 mpaka 1.5 V monga ntchito ya Eocp pa scan rate ya 0.166 mV / s.Chiyeso chilichonse chinabwerezedwa 3 nthawi ndi popanda P. aeruginosa.
Zitsanzo za kusanthula kwa metallographic zidapukutidwa ndi pepala lonyowa la 2000 grit SiC ndiyeno kupukutidwanso ndi kuyimitsidwa kwa ufa wa 0.05 µm Al2O3 kuti muwonetsetse.Kusanthula kwazitsulo kunachitidwa pogwiritsa ntchito microscope ya kuwala.Zitsanzozo zidakhazikika ndi 10 wt% yankho la potaziyamu hydroxide 43.
Pambuyo pa kukulitsidwa, zitsanzozo zinatsukidwa 3 nthawi ndi phosphate buffered saline (PBS) (pH 7.4 ± 0.2) kenako ndi 2.5% (v / v) glutaraldehyde kwa maola 10 kukonza biofilms.Kenako madziwo anali ndi batched Mowa (50%, 60%, 70%, 80%, 90%, 95% ndi 100% ndi voliyumu) ​​pamaso kuyanika mpweya.Pomaliza, filimu yagolide imayikidwa pamwamba pa chitsanzo kuti ipereke mawonekedwe a SEM.Zithunzi za SEM zinkayang'ana pa mawanga omwe ali ndi maselo a sessile a P. aeruginosa pamwamba pa chitsanzo chilichonse.Chitani kafukufuku wa EDS kuti mupeze mankhwala.Makina a Zeiss confocal laser scanning microscope (CLSM) (LSM 710, Zeiss, Germany) anagwiritsidwa ntchito kuyeza kuya kwa dzenje.Kuti muwone maenje a dzimbiri pansi pa biofilm, zitsanzo zoyeserera zidatsukidwa molingana ndi Chinese National Standard (CNS) GB/T4334.4-2000 kuti achotse zinthu zowonongeka ndi biofilm pamwamba pa mayeso.
X-ray photoelectron spectroscopy (XPS, ESCALAB250 yowunikira pamwamba, Thermo VG, USA) kusanthula kunachitika pogwiritsa ntchito gwero la X-ray la monochromatic (Aluminium Kα line yokhala ndi mphamvu ya 1500 eV ndi mphamvu ya 150 W) mumitundu yosiyanasiyana. Kumanga mphamvu 0 pansi pazikhalidwe za -1350 eV.Mawonekedwe apamwamba adalembedwa pogwiritsa ntchito mphamvu yotumizira ya 50 eV ndi sitepe ya 0.2 eV.
Zitsanzo zotsekedwa zinachotsedwa ndikutsukidwa mofatsa ndi PBS (pH 7.4 ± 0.2) kwa 15 s45.Kuti muwone momwe mabakiteriya amathandizira pazitsanzo, ma biofilms adadetsedwa pogwiritsa ntchito LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, USA).Zidazi zili ndi mitundu iwiri ya fulorosenti: utoto wa SYTO-9 wobiriwira wa fulorosenti ndi utoto wa propidium iodide (PI) wofiira wa fulorosenti.Mu CLSM, madontho obiriwira ndi ofiira a fulorosenti amaimira maselo amoyo ndi akufa, motsatira.Pothimbirira, 1 ml ya osakaniza okhala ndi 3 µl wa SYTO-9 ndi 3 µl wa PI solution adakulungidwa kwa mphindi 20 kutentha kwachipinda (23 ° C) mumdima.Pambuyo pake, zitsanzo zothimbirira zidawunikidwa pamafunde awiri (488 nm kwa ma cell amoyo ndi 559 nm kwa maselo akufa) pogwiritsa ntchito zida za Nikon CLSM (C2 Plus, Nikon, Japan).Makulidwe a biofilm adayesedwa mu 3D scanning mode.
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