Zotsatira za Pseudomonas aeruginosa Marine Biofilm pa Microbial Corrosion ya 2707 Super Duplex Stainless Steel

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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, kuthekera kwa dzimbiri kunasintha bwino, komanso kuchuluka kwa dzimbiri komwe kukuchulukirachulukira.Zotsatira za X-ray photoelectron spectroscopy (XPS) zinawonetsa kuchepa kwa Cr zomwe zili pachitsanzo pansi pa biofilm.Kuwunika kwa zithunzi za dzenje kunawonetsa kuti ma biofilms a Pseudomonas aeruginosa adapanga dzenje lozama kwambiri la 0.69 µm pambuyo pa masiku 14 achikhalidwe.Ngakhale izi ndizochepa, zimasonyeza kuti 2707 HDSS sichitetezedwa kwathunthu ndi zotsatira za P. aeruginosa biofilms pa MIC.
Chitsulo chosapanga dzimbiri cha Duplex (DSS) chimagwiritsidwa ntchito kwambiri m'mafakitale osiyanasiyana chifukwa cha kuphatikiza kwabwino kwamakina komanso kukana dzimbiri1,2.Komabe, kupindika komweko kumatha kuchitika, zomwe zingakhudze kukhulupirika kwachitsulo ichi 3, 4.DSS sichitetezedwa ku tizilombo toyambitsa matenda (MIC)5,6.Ngakhale mawonekedwe a DSS ndi otakata kwambiri, pali malo omwe kukana kwa dzimbiri kwa DSS sikukwanira kugwiritsidwa ntchito kwanthawi yayitali.Izi zikutanthawuza kuti zipangizo zokwera mtengo zokhala ndi kukana kwa dzimbiri zimafunika.Jeon et al.7 adapeza kuti ngakhale chitsulo chosapanga dzimbiri cha duplex (SDSS) chili ndi malire pokana dzimbiri.Chifukwa chake, pakufunika zitsulo zosapanga dzimbiri zosapanga dzimbiri (HDSS) zokhala ndi kukana kwa dzimbiri muzinthu zina.Izi zidapangitsa kuti ma HDSS apangidwe kwambiri.
Kukaniza kwa dzimbiri kwa DSS kumatsimikiziridwa ndi chiŵerengero cha α-gawo ku γ-gawo ndi madera omwe amachotsedwa mu Cr, Mo ndi W pafupi ndi zigawo zachiwiri8,9,10.HDSS ili ndi zambiri za Cr, Mo ndi N11, zomwe zimapatsa kukana kwa dzimbiri komanso mtengo wapamwamba (45-50) wofanana ndi pitting resistance value (PREN), womwe umatanthauzidwa 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 yapititsa patsogolo makina komanso kukana kwa chlorine poyerekeza ndi DSS13 wamba.Makhalidwe a mankhwala dzimbiri.Kukhazikika kwa dzimbiri kumakulitsa kugwiritsa ntchito HDSS m'malo owopsa a chloride monga madera am'madzi.
MIC ndi vuto lalikulu m'mafakitale ambiri, kuphatikiza mafuta ndi gasi ndi madzi14.MIC imapanga 20% ya zowonongeka zonse15.MIC ndi corrosion ya bioelectrochemical yomwe imatha kuwonedwa m'malo ambiri16.Mapangidwe a biofilms pazitsulo zachitsulo amasintha ma electrochemical zinthu ndipo motero zimakhudza njira ya dzimbiri.Ndizovomerezeka kuti MIC corrosion imayambitsidwa ndi biofilms14.Tizilombo tating'onoting'ono timadya zitsulo kuti tipeze mphamvu kuti tipulumuke17.Kafukufuku waposachedwa wa MIC wasonyeza kuti EET (extracellular electron transfer) ndiye chinthu cholepheretsa MIC choyambitsidwa ndi ma electrogenic microorganisms.Zhang et al.18 adawonetsa kuti oyimira ma elekitironi amafulumizitsa kusamutsa ma elekitironi pakati pa ma cell a Desulfovibrio vulgaris sessile ndi 304 zitsulo zosapanga dzimbiri, zomwe zimapangitsa kuti pakhale kuukira koopsa kwa MIC.Anning ndi al.19 ndi Wenzlaff et al.20 awonetsa kuti mabakiteriya a corrosive sulfate-reducing bacteria (SRBs) amatha kuyamwa ma elekitironi mwachindunji kuchokera kuzitsulo zazitsulo, 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 biofilm22,23.Mosiyana ndi DSS, ndizochepa zomwe zimadziwika za MIC HDSS24.
Pseudomonas aeruginosa ndi kachilombo ka Gram-negative, motile, ngati ndodo yomwe imafalitsidwa kwambiri mu chilengedwe25.Pseudomonas aeruginosa ndiyenso tizilombo toyambitsa matenda tomwe timayambitsa MIC yachitsulo m'malo am'madzi26.Mitundu ya Pseudomonas imakhudzidwa mwachindunji ndi njira za dzimbiri ndipo imadziwika kuti ndiyo oyamba kutsamira pakupanga biofilm27.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 ndikuwerenga za MIC za 2707 HDSS zomwe zimayambitsidwa ndi mabakiteriya amadzimadzi 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 dynamic polarization yomwe ingathe kuchitika adachitidwa kuti aphunzire machitidwe a MIC 2707 HDSS.Kusanthula kwa Energy dispersive spectroscopy (EDS) kumapangidwa kuti azindikire zinthu zamakemikolo pamalo ochita dzimbiri.Kuphatikiza apo, kukhazikika kwa filimu ya oxide passivation mothandizidwa ndi malo am'madzi okhala ndi Pseudomonas aeruginosa adatsimikiziridwa ndi X-ray photoelectron spectroscopy (XPS).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.Magulu otalikirapo a magawo austenitic ndi ferritic popanda magawo achiwiri amatha kuwoneka mu microstructure yomwe ili ndi pafupifupi 50% austenitic ndi 50% ferritic phases.
Pa mkuyu.2a ikuwonetsa kuthekera kwa dera lotseguka (Eocp) motsutsana ndi nthawi yowonekera kwa 2707 HDSS mu 2216E abiotic medium ndi msuzi wa Pseudomonas aeruginosa kwa masiku 14 pa 37 ° C.Zinapezeka kuti zosintha zodziwika kwambiri mu Eocp zidachitika m'maola 24 oyamba.Miyezo ya Eocp muzochitika zonsezi idakwera pafupifupi -145 mV (kuyerekeza ndi SCE) pafupifupi maola 16 kenako idatsika kwambiri mpaka -477 mV (motsutsana ndi SCE) ndi -236 mV (motsutsana ndi SCE) pazitsanzo zomwe si zachilengedwe ndi P kwa wachibale. SCE) masamba a patina, motsatana.Pambuyo pa maola 24, mtengo wa Eocp wa Pseudomonas aeruginosa 2707 HDSS unakhalabe wosasunthika pa -228 mV (poyerekeza ndi SCE), pamene mtengo wofanana wa zitsanzo zomwe sizinali zamoyo zinali pafupifupi -442 mV (poyerekeza ndi SCE).Eocp pamaso pa Pseudomonas aeruginosa inali yotsika kwambiri.
Kuyesa kwa electrochemical kwa zitsanzo za 2707 HDSS mu abiotic media ndi Pseudomonas aeruginosa msuzi pa 37 ° C:
(a) Kusintha kwa Eocp ndi nthawi yowonekera, (b) piritsi la polarization pa tsiku 14, (c) kusintha kwa Rp ndi nthawi yowonekera, (d) kusintha kwa Corr ndi nthawi yowonekera.
Table 3 ikuwonetsa magawo a electrochemical corrosion a 2707 HDSS zitsanzo zowonetsedwa ndi abiotic ndi P. aeruginosa incorder media kwa masiku 14.Tangential extrapolation of anodic and cathodic curves to intersection point inalola kutsimikiza kwa corrosion current density (icorr), corrosion potential (Ecorr) ndi Tafel slope (βα ndi βc) malinga ndi njira zokhazikika30,31.
Monga momwe tawonetsera pa Chithunzi 2b, kusuntha kwapamwamba kwa P. aeruginosa curve kunapangitsa kuwonjezeka kwa Ecorr poyerekeza ndi curve ya abiotic.Mtengo wa icorr wa chitsanzo chokhala ndi Pseudomonas aeruginosa, molingana ndi kuchuluka kwa dzimbiri, udakwera kufika pa 0.328 µA cm-2, womwe ndi wokulirapo kanayi kuposa wa zitsanzo zomwe sizinali zamoyo (0.087 µA cm-2).
LPR ndi njira yachikale yamagetsi yama electrochemical pakuwunika kosawonongeka kwa dzimbiri.Yagwiritsidwanso ntchito pophunzira MIC32.Pa mkuyu.2c ikuwonetsa kusintha kwa kukana kwa polarization (Rp) kutengera 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 zomwe sizinali zamoyo 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 mayeso a 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 malo otsetsereka a Tafel B adatengedwa ngati mtengo wamba wa 26 mV/dec pantchitoyi.Pa mkuyu.2d ikuwonetsa kuti icorr ya 2707 abiotic strain idakhalabe yokhazikika, pomwe icorr ya gulu la Pseudomonas aeruginosa idasinthasintha kwambiri ndi kulumpha kwakukulu pambuyo pa maola 24 oyamba.Mtengo wa icorr wa chitsanzo cha mayeso a Pseudomonas aeruginosa unali wochulukira kwambiri kuposa wowongolera omwe si wachilengedwe.Izi zikugwirizana ndi zotsatira za polarization resistance.
EIS ndi njira ina yosawononga yomwe imagwiritsidwa ntchito kuwonetsa machitidwe a electrochemical pa corrosion interface34.Impedance spectra ndi capacitance kuwerengera kwa mizere yomwe imawululidwa ku abiotic media ndi mayankho a Pseudomonas aeruginosa, Rb ndi kukana kwa passive/biofilm yomwe imapangidwa pamwamba pa mzere, Rct ndiye kukana kusamutsa, Cdl ndi gawo lamagetsi lawiri.) ndi magawo a QCPE constant phase element (CPE).Magawo awa adawunikidwanso poyerekeza deta ndi mtundu wofanana wamagetsi (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 Pseudomonas aeruginosa nthawi zosiyanasiyana zomakulitsidwa.Pamaso pa Pseudomonas aeruginosa, kutalika kwa loop ya Nyquist kumachepa.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 ndi EEC yofananira yokhazikika pagawo limodzi (a) ndi magawo awiri (b).CPE imayambitsidwa mu chitsanzo cha EEC.Kuloledwa kwake ndi kulepheretsa kwake kumawonetsedwa motere:
Zitsanzo ziwiri zakuthupi ndi mabwalo ofanana kuti agwirizane ndi 2707 HDSS coupon impedance spectrum:
Kumene Y0 ndi kukula kwa CPE, j ndi nambala yongoganizira kapena (-1) 1/2, ω ndi ma frequency aang'ono, ndipo n ndi mphamvu ya CPE yocheperapo imodzi35.Kusintha kwa kukana kwa ndalama (ie 1/Rct) kumafanana ndi kuchuluka kwa dzimbiri.Mtengo wotsika wa Rct umatanthauza kuchuluka kwa dzimbiri27.Pambuyo pa masiku 14 a incubation, Rct ya mayeso a Pseudomonas aeruginosa inafika pa 32 kΩ cm2, yomwe ndi yocheperapo kuposa 489 kΩ cm2 ya chitsanzo chopanda zamoyo (Table 4).
Zithunzi za CLSM ndi zithunzi za SEM mumkuyu.5 ikuwonetsa momveka bwino kuti kuphimba kwa biofilm pamwamba pa HDSS sampuli 2707 kunali kolimba kwambiri patatha masiku 7.Komabe, patatha masiku 14 zokutira za biofilm zidachepa ndipo maselo ena akufa adawonekera.Table 5 ikuwonetsa makulidwe a biofilm a zitsanzo za 2707 HDSS pambuyo pa masiku 7 ndi 14 atakumana ndi Pseudomonas aeruginosa.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 biofilm ndi zinthu zowononga pazitsanzo zowululidwa ndi Pseudomonas aeruginosa kwa masiku 14.Pa mkuyu.Chithunzi 6 chikuwonetsa kuti zomwe zili mu C, N, O, P mu biofilm ndi zinthu zowonongeka ndizokwera kwambiri kuposa zitsulo zoyera, chifukwa zinthuzi zimagwirizana ndi biofilm ndi metabolites.Tizilombo tating'onoting'ono timangofuna kuchuluka kwa Cr ndi Fe.Zomwe zili pamwamba pa Cr ndi Fe mu biofilm ndi zinthu zowonongeka pamwamba pa chitsanzo zimasonyeza kutayika kwa zinthu muzitsulo zachitsulo chifukwa cha kuwonongeka.
Pambuyo pa masiku 14, maenje okhala ndi P. aeruginosa adawonedwa mkatikati mwa 2216E.Pamaso makulitsidwe, padziko zitsanzo anali yosalala ndi opanda chilema (mkuyu. 7a).Pambuyo poyambitsa ndi kuchotsedwa kwa biofilm ndi zinthu zowonongeka, maenje ozama kwambiri pamwamba pa chitsanzo 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 Pseudomonas aeruginosa kunali 0.52 µm patatha masiku 7 ndi 0.69 µm patatha masiku 14, kutengera kuchuluka kwa dzenje lakuya kuchokera ku zitsanzo za 3 (kuzama kwa dzenje 10 kunasankhidwa pachitsanzo chilichonse) ndikufikira 0. 42 ± 0.12 µm .ndi 0.52 ± 0.15 µm, motsatana (Table 5).Zozama za dimple izi ndizochepa koma ndizofunikira.
(a) asanakumane;(b) masiku 14 mu chilengedwe;(c) Masiku 14 mu msuzi wa P. aeruginosa.
Pa mkuyu.Table 8 ikuwonetsa mawonekedwe a XPS a mawonekedwe osiyanasiyana a zitsanzo, ndipo chemistry yomwe imawunikiridwa pamalo aliwonse akufotokozedwa mwachidule mu Table 6. Patebulo 6, ma atomiki a Fe ndi Cr anali otsika kwambiri pamaso pa P. aeruginosa (zitsanzo A ndi B ) kusiyana ndi mizere yoyang'anira yomwe si yachilengedwe.(zitsanzo C ndi D).Pachitsanzo cha Pseudomonas aeruginosa, Cr 2p core level spectral curve idalumikizidwa ku zigawo zinayi zapamwamba zokhala ndi mphamvu zomangirira (BE) za 574.4, 576.6, 578.3 ndi 586.8 eV, zomwe zidaperekedwa kwa Cr, Cr2O3, CR(O3, CR(O3) ndi CR(O3) 3, motero (mkuyu 9a ndi b).Kwa zitsanzo zopanda zamoyo, mawonekedwe apakati pa Cr 2p mu Fig.9c ndi d ili ndi nsonga ziwiri zazikulu za Cr (BE 573.80 eV) ndi Cr2O3 (BE 575.90 eV), motsatira.Kusiyana kochititsa chidwi kwambiri pakati pa kuponi ya abiotic ndi kuponi ya P. aeruginosa kunali kupezeka kwa Cr6+ ndi kachigawo kakang'ono ka Cr(OH)3 (BE 586.8 eV) pansi pa biofilm.
Broad surface XPS spectra of 2707 HDSS zitsanzo mu media ziwiri kwa 7 ndi 14 masiku, motsatana.
(a) 7 masiku 7 P. aeruginosa kukhudzana, (b) 14 masiku P. aeruginosa kukhudzana, (c) 7 masiku abiootic kukhudzana, (d) 14 masiku abiootic kukhudzana.
HDSS imawonetsa kukana kwambiri kwa dzimbiri m'malo ambiri.Kim et al.2 adanena kuti HDSS UNS S32707 idadziwika kuti ndi DSS yochuluka kwambiri yokhala ndi PREN yoposa 45. Mtengo wa PREN wa HDSS chitsanzo 2707 mu ntchitoyi unali 49. Izi ndichifukwa cha Cr yapamwamba komanso mayendedwe apamwamba a Mo ndi Ni, omwe ndi othandiza m'malo acidic ndi malo okhala ndi ma chloride ambiri.Kuphatikiza apo, mawonekedwe osakanikirana bwino komanso ma microstructure opanda chilema amapereka kukhazikika kwadongosolo komanso kukana dzimbiri.Ngakhale kukana kwamankhwala kwabwino kwambiri, zoyeserera mu ntchitoyi zikuwonetsa kuti 2707 HDSS sichitetezedwa kwathunthu ndi Pseudomonas aeruginosa biofilm MICs.
Zotsatira za electrochemical zikuwonetsa kuti kuchuluka kwa dzimbiri kwa 2707 HDSS mu msuzi wa Pseudomonas aeruginosa kunakula kwambiri pambuyo pa masiku 14 poyerekeza ndi malo omwe siachilengedwe.Mu chithunzi 2a, kuchepa kwa Eocp kunawonedwa mu abiotic sing'anga ndi P. aeruginosa msuzi m'maola 24 oyamba.Pambuyo pake, biofilm imamaliza kuphimba pamwamba pa chitsanzocho ndipo Eocp imakhala yokhazikika.Komabe, mulingo wa biotic Eocp unali wapamwamba kwambiri kuposa mulingo wa abiotic Eocp.Pali zifukwa zokhulupirira kuti kusiyana kumeneku kumagwirizana ndi mapangidwe a P. aeruginosa biofilms.Pa mkuyu.2g, mtengo wa icorr wa 2707 HDSS unafika pa 0.627 µA cm-2 pamaso pa Pseudomonas aeruginosa, yomwe ndi dongosolo lapamwamba kwambiri kuposa la mphamvu zopanda chilengedwe (0.063 µA cm-2), zomwe zimagwirizana ndi Rct Mtengo wapatali wa magawo EIS.M'masiku angapo oyambilira, kufunikira kwa p. aeruginosa msuzi kumawonjezeka chifukwa cha kulumikizidwa kwa maselo a P. aeruginosa ndi mapangidwe a biofilm.Komabe, kusokoneza kumachepa pamene biofilm imaphimba zonse pamwamba pa chitsanzo.Wosanjikiza woteteza amawukiridwa makamaka chifukwa cha mapangidwe a biofilm ndi biofilm metabolites.Chifukwa chake, kukana kwa dzimbiri kumachepa pakapita nthawi, ndipo ma depositi a Pseudomonas aeruginosa amayambitsa dzimbiri mdera lanu.Zomwe zimachitika m'malo abiotic ndizosiyana.Kukana kwa dzimbiri kwa kuwongolera kosakhala kwachilengedwe kunali kokwera kwambiri kuposa mtengo wofananira wa zitsanzo zomwe zimawonekera ku msuzi wa Pseudomonas aeruginosa.Kuphatikiza apo, pazitsanzo za abiotic, mtengo wa Rct 2707 HDSS unafika 489 kΩ cm2 patsiku la 14, womwe ndi wokwera nthawi 15 kuposa Pseudomonas aeruginosa (32 kΩ cm2).Chifukwa chake, 2707 HDSS ili ndi kukana bwino kwa dzimbiri m'malo osabala, koma sikutetezedwa ku MIC kuukira ndi Pseudomonas aeruginosa biofilm.
Zotsatirazi zitha kuwonedwanso kuchokera ku ma curve polarization mu Mkuyu.2b .Anodic nthambi imagwirizana ndi Pseudomonas aeruginosa biofilm mapangidwe ndi zitsulo oxidation reactions.Pa nthawi yomweyo, cathodic anachita ndi kuchepetsa mpweya.Kukhalapo kwa P. aeruginosa kumawonjezera kuchuluka kwa dzimbiri, komwe kunali pafupi ndi dongosolo la ukulu wake kuposa momwe amalamulira abiotic.Izi zidawonetsa kuti Pseudomonas aeruginosa biofilm idakulitsa dzimbiri komweko kwa 2707 HDSS.Yuan et al.29 adapeza kuti kuchuluka kwa dzimbiri kwaposachedwa kwa 70/30 Cu-Ni alloy kunawonjezeka ndi Pseudomonas aeruginosa biofilm.Izi zitha kukhala chifukwa cha biocatalysis ya kuchepetsa mpweya ndi Pseudomonas aeruginosa biofilm.Izi zitha kufotokozeranso za MIC 2707 HDSS pantchitoyi.Aerobic biofilms amathanso kuchepetsa mpweya womwe uli pansi pawo.Choncho, kukana kubwezeretsa zitsulo pamwamba ndi mpweya kungakhale chinthu chomwe chimapangitsa kuti MIC igwire ntchitoyi.
Dickinson ndi al.38 inanena kuti kuchuluka kwa machitidwe amankhwala ndi ma electrochemical mwachindunji kumadalira kagayidwe kachakudya ka mabakiteriya omwe amakhala pachitsanzo komanso mawonekedwe azinthu 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 maselo ambiri okhazikika pamtunda wa 2707 HDSS adafa chifukwa cha kuchepa kwa michere mu sing'anga ya 2216E kapena kutulutsidwa kwa ayoni achitsulo chapoizoni kuchokera ku 2707 HDSS matrix.Izi ndizochepa zoyeserera zamagulu.
Mu ntchitoyi, Pseudomonas aeruginosa biofilm inalimbikitsa kuchepa kwa Cr ndi Fe pansi pa biofilm pamwamba pa 2707 HDSS (Mkuyu 6).Mu Table 6, Fe ndi Cr adachepa chitsanzo cha D poyerekeza ndi chitsanzo C, kusonyeza kuti Fe ndi Cr kusungunuka chifukwa cha P. aeruginosa biofilm kunasungidwa pambuyo pa 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- chinali chifukwa chachikulu cha kuchepa kwa Cr m'masiku 7 ndi masiku 14 omwe sanali achilengedwe omwe amafufuzidwa ndi XPS.Poyerekeza ndi chitsanzo choyesera cha Pseudomonas aeruginosa, kusungunuka kwa Cr mu chitsanzo choyesera cha abiotic ndikochepa kwambiri chifukwa cha kukana kwamphamvu kwa 2707 HDSS ku chlorine m'malo abiotic.Pa mkuyu.9 ikuwonetsa kukhalapo kwa Cr6 + mufilimuyi.Izi zikhoza kukhala zokhudzana ndi kuchotsedwa kwa Cr kuchokera kuzitsulo zazitsulo ndi P. aeruginosa biofilms, monga momwe Chen ndi Clayton39 adafotokozera.
Chifukwa cha kukula kwa bakiteriya, pH ya sing'anga isanayambe komanso itatha kukulitsidwa inali 7.4 ndi 8.2, motsatana.Chifukwa chake, kuwonongeka kwa ma organic acid sikungatheke kuti athandizire ntchitoyi pansi pa P. aeruginosa biofilms 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 mu inoculum sing'anga pambuyo poyamwitsa kunalumikizidwa ndi kagayidwe kachakudya ka Pseudomonas aeruginosa, ndipo zotsatira zomwezo pa pH zidapezeka popanda mzere woyeserera.
Monga zikuwonetsedwa mkuyu.7, kuzama kwakukulu kwa dzenje komwe kunayambika ndi Pseudomonas aeruginosa biofilm kunali 0.69 µm, komwe kuli kokulirapo kuposa komwe kumakhala mu abiotic medium (0.02 µm).Izi zimagwirizana ndi zomwe zili pamwambazi za electrochemical.Pansi pamikhalidwe yomweyi, kuya kwa dzenje la 0.69 µm ndikocheperako kuwirikiza kakhumi kuposa mtengo wa 9.5 µm wotchulidwa 2205 DSS40.Izi zikuwonetsa kuti 2707 HDSS ikuwonetsa kukana bwino kwa MICs kuposa 2205 DSS.Izi sizosadabwitsa popeza 2707 HDSS ili ndi mulingo wapamwamba kwambiri wa Cr, womwe umalola kupitilira kwakanthawi, kumapangitsa Pseudomonas aeruginosa kukhala yovuta kuyimitsa, ndikuyambitsa njirayo popanda kuvula kwachiwiri kovulaza Pitting41.
Pomaliza, kuponyedwa kwa MIC kunapezeka pa 2707 HDSS pamadzi a Pseudomonas aeruginosa msuzi, pomwe kuponya kunali kosavomerezeka muzambiri za abiotic.Ntchitoyi ikuwonetsa kuti 2707 HDSS ili ndi kukana bwino kwa MIC kuposa 2205 DSS, koma sikutetezedwa kwathunthu ndi MIC chifukwa cha Pseudomonas aeruginosa biofilm.Zotsatirazi zimathandizira pakusankha zitsulo zosapanga dzimbiri zoyenera komanso moyo wokhala ndi moyo wam'madzi.
Zitsanzo za 2707 HDSS zinaperekedwa ndi School of Metallurgy, Northeastern University (NEU), Shenyang, China.Kupangidwa koyambirira kwa 2707 HDSS kukuwonetsedwa mu Table 1, yomwe idawunikidwa ndi dipatimenti yowunikira ndi kuyesa zida ku Northeastern University.Zitsanzo zonse zimathandizidwa kuti zikhale zolimba pa 1180 ° C kwa ola limodzi.Asanayezetse dzimbiri, chitsulo cha 2707 HDSS chokhala ndi malo owonekera 1 cm2 chidapukutidwa mpaka grit 2000 ndi sandpaper ya silicon carbide ndikupukutidwanso 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 strain Pseudomonas aeruginosa MCCC 1A00099 idagulidwa kuchokera ku Xiamen Marine Culture Collection (MCCC), China.Marine 2216E liquid medium (Qingdao Hope Biotechnology Co., Ltd., Qingdao, China) idagwiritsidwa ntchito popanga Pseudomonas aeruginosa mu 250 ml ma flasks ndi 500 ml magalasi agalasi a electrochemical pansi pamikhalidwe ya aerobic pa 37 ° C.Sipakatikati ili ndi (g/l): 19.45 NaCl, 5.98 MgCl2, 3.24 Na2SO4, 1.8 CaCl2, 0.55 KCl, 0.16 Na2CO3, 0.08 KBr, 0.034 SrCl2, 0.08 2 030 030, 0.08 SrCl2, 2, 3, 2, 3, 2, 3, 3, 3, 3, 2, 2, 3, 3, 3, 3, 2, 3, 3, 3, 4, 10, 0. 0.008, 0.008 Na4F0H20PO.1.0 chotsitsa yisiti ndi 0.1 iron citrate.Autoclave pa 121 ° C kwa mphindi 20 musanayambe kulowetsedwa.Maselo a Sessile ndi planktonic adawerengedwa pansi pa microscope yowala pogwiritsa ntchito hemocytometer pa 400x magnification.Kuchuluka kwa maselo a planktonic P. aeruginosa mwamsanga pambuyo pa inoculation anali pafupifupi 106 maselo/mL.
Mayeso a electrochemical adachitika mu cell yagalasi yama electrode atatu okhala ndi sing'anga 500 ml.Tsamba la platinamu ndi electrode yodzaza ndi calomel (SCE) idalumikizidwa ndi chojambulira kudzera mu capillary ya Luggin yodzazidwa ndi mlatho wamchere ndipo idagwiritsidwa ntchito ngati ma electrode owerengera ndi mafotokozedwe, motsatana.Kuti apange electrode yogwira ntchito, waya wamkuwa wopangidwa ndi mphira amamangiriridwa ku chitsanzo chilichonse ndikukutidwa ndi epoxy, kusiya pafupifupi 1 cm2 yamtunda kumbali imodzi ya electrode yogwira ntchito.Pamiyeso ya electrochemical, zitsanzozo zinayikidwa mu sing'anga ya 2216E ndikusungidwa kutentha kosalekeza (37 ° C) mumadzi osamba.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 rate ya 0.125 mV s-1 mu -5 ndi 5 mV range ndi Eocp ndi chitsanzo cha 1 Hz.EIS inkachitidwa pa Eocp yokhazikika pogwiritsa ntchito mphamvu yamagetsi ya 5 mV yokhala ndi sinusoid pamtundu wafupipafupi wa 0.01 mpaka 10,000 Hz.Asanayambe kusesa, ma elekitirodi anali mumayendedwe otseguka mpaka mphamvu yokhazikika ya 42 yokhazikika.Ndi.Chiyeso chilichonse chinabwerezedwa katatu ndi popanda Pseudomonas aeruginosa.
Zitsanzo za kusanthula kwa metallographic zidapukutidwa mwamakina ndi pepala lonyowa la SiC la 2000 grit kenako ndikupukutidwa ndi 0.05 µm Al2O3 ufa slurry kuti muwone bwino.Kusanthula kwazitsulo kunachitidwa pogwiritsa ntchito microscope ya kuwala.Chitsanzocho chinakhazikitsidwa ndi 10 wt% potassium hydroxide solution43.
Pambuyo pa kukulitsidwa, sambani katatu ndi phosphate buffered saline (PBS) (pH 7.4 ± 0.2) ndiyeno konzekerani ndi 2.5% (v/v) glutaraldehyde kwa maola 10 kuti mukonze biofilm.Kenako madzi m`thupi ndi Mowa mu anaponda angapo (50%, 60%, 70%, 80%, 90%, 95% ndi 100% ndi voliyumu) ​​pamaso kuyanika mpweya.Pomaliza, filimu yagolide idayikidwa pamwamba pa chitsanzocho kuti ipereke mawonekedwe a SEM44.Zithunzi za SEM zimayang'ana pa malo omwe ali ndi maselo okhazikika a P. aeruginosa pamwamba pa chitsanzo chilichonse.Kusanthula kwa EMF kunachitika kuti azindikire zinthu zamakemikolo.Pofuna kuyeza kuya kwa dzenjelo, anagwiritsa ntchito makina oonera maikulosikopu a Zeiss confocal laser (CLSM) (LSM 710, Zeiss, Germany).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 Surface Analysis System, Thermo VG, USA) kusanthula pogwiritsa ntchito gwero la X-ray la monochromatic (Al Kα mzere wokhala ndi mphamvu ya 1500 eV ndi mphamvu ya 150 W) mu mphamvu zambiri zomangira. 0 pansi pazikhalidwe za -1350 eV.Jambulani mawonekedwe apamwamba kwambiri pogwiritsa ntchito mphamvu ya 50 eV pass ndi 0.2 eV step size.
Chotsani chitsanzo chokulitsidwa ndikutsuka pang'onopang'ono ndi PBS (pH 7.4 ± 0.2) kwa 15 s45.Kuti muwone kutheka kwa bakiteriya wa biofilm pachitsanzocho, biofilm idadetsedwa 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.Pothirira, sungani 1 ml ya osakaniza okhala ndi 3 µl wa SYTO-9 ndi 3 µl wa PI solution pa kutentha kwapakati (23 ° C) mumdima kwa mphindi 20.Pambuyo pake, zitsanzo zodetsedwa zidawonedwa pamafunde awiri (488 nm yama cell amoyo ndi 559 nm yama cell akufa) pogwiritsa ntchito zida za Nikon CLSM (C2 Plus, Nikon, Japan).Yezerani makulidwe a biofilm mu 3-D scanning mode.
Momwe mungatchulire nkhaniyi: Li, H. et al.Zotsatira za Pseudomonas aeruginosa marine biofilm pa microbial corrosion ya 2707 super duplex chitsulo chosapanga dzimbiri.sayansi.Nyumba 6, 20190;doi:10.1038/srep20190 (2016).
Zanotto, F., Grassi, V., Balbo, A., Monticelli, C. & Zucchi, F. Stress corrosion cracking ya LDX 2101 duplex zitsulo zosapanga dzimbiri muzitsulo za chloride pamaso pa thiosulfate.dzimbiri.sayansi.80, 205-212 (2014).
Kim, ST, Jang, SH, Lee, IS ndi Park, YS Mphamvu ya chithandizo cha kutentha kwa yankho ndi nayitrogeni poteteza gasi pamakina okanira corrosion wa super duplex zitsulo zosapanga dzimbiri.dzimbiri.sayansi.53, 1939-1947 (2011).
Shi, X., Avchi, R., Geyser, M. ndi Lewandowski, Z. Kafukufuku woyerekeza ndi mankhwala a microbial ndi electrochemical pitting mu 316L chitsulo chosapanga dzimbiri.dzimbiri.sayansi.45, 2577–2595 (2003).
Luo H., Dong KF, Li HG ndi Xiao K. Electrochemical khalidwe la 2205 duplex zitsulo zosapanga dzimbiri muzitsulo zamchere pamitundu yosiyanasiyana ya pH pamaso pa chloride.electrochemistry.Journal.64, 211-220 (2012).