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I-Microbial corrosion (MIC) iyinkinga enkulu ezimbonini eziningi, njengoba ingaholela ekulahlekelweni okukhulu kwezomnotho.I-Super duplex stainless steel 2707 (2707 HDSS) isetshenziswa ezindaweni zasolwandle ngenxa yokumelana kwayo okuhle kakhulu namakhemikhali.Kodwa-ke, ukumelana kwayo ne-MIC akukaze kuboniswe ngokuhlolwa.Lolu cwaningo luhlole ukuziphatha kwe-MIC 2707 HDSS okubangelwa i-marine aerobic bacterium i-Pseudomonas aeruginosa.Ukuhlaziywa kwe-Electrochemical kubonise ukuthi phambi kwe-Pseudomonas aeruginosa biofilm ku-2216E medium, ushintsho oluhle emandleni okugqwala kanye nokwanda kwenani lamanje lokugqwala kwenzeka.Ukuhlaziywa kwe-X-ray photoelectron spectroscopy (XPS) kubonise ukwehla kokuqukethwe kwe-Cr ebusweni besampula ngaphansi kwe-biofilm.Ukuhlaziya okubukwayo kwemigodi kubonise ukuthi i-P. aeruginosa biofilm ikhiqize ukujula komgodi okukhulu okungu-0.69 µm phakathi nezinsuku eziyi-14 zokufukamela.Nakuba lokhu kukuncane, kubonisa ukuthi i-2707 HDSS ayivikelekile ngokuphelele ku-MIC ye-P. aeruginosa biofilms.
I-Duplex stainless steels (DSS) isetshenziswa kabanzi ezimbonini ezihlukahlukene ngenxa yenhlanganisela ephelele yezakhiwo ezinhle kakhulu zemishini kanye nokumelana nokugqwala1,2.Nokho, umgodi wendawo usenzeka futhi uthinta ubuqotho bale steel3,4.I-DSS ayimelani ne-microbial corrosion (MIC)5,6.Ngaphandle kobubanzi obubanzi bezicelo ze-DSS, kusenezindawo lapho ukumelana nokugqwala kwe-DSS kunganele ukusetshenziswa isikhathi eside.Lokhu kusho ukuthi izinto ezibiza kakhulu ezinokumelana nokugqwala okuphezulu ziyadingeka.UJeon et al7 bathole ukuthi ngisho nezinsimbi ezingenasici eziyi-duplex (SDSS) zinemikhawulo ethile mayelana nokumelana nokugqwala.Ngakho-ke, kwezinye izimo, i-super duplex stainless steels (HDSS) enokumelana nokugqwala okuphezulu kuyadingeka.Lokhu kuholele ekuthuthukisweni kwe-HDSS ene-alloyed kakhulu.
Ukumelana nokugqwala kwe-DSS kuncike esilinganisweni sezigaba ze-alpha ne-gamma futhi kuncishiswe ezifundeni ze-Cr, Mo kanye ne-W 8, 9, 10 ezincikene nesigaba sesibili.I-HDSS iqukethe okuqukethwe okuphezulu kwe-Cr, Mo kanye ne-N11, ngakho-ke inokumelana nokugqwala okuhle kakhulu kanye nenani eliphakeme (45-50) lenombolo yokumelana ne-pitting efanayo (PREN) enqunywe ngu-wt.% Cr + 3.3 (wt.% Mo + 0.5 wt.%W) + 16% wt.N12.Ukumelana nokugqwala kwayo okuhle kakhulu kuncike ekwakhiweni okunokulinganisela okuqukethe cishe izigaba ze-ferritic (α) nezingu-50% ze-austenitic (γ).I-HDSS inezakhiwo ezingcono zomshini kanye nokumelana okuphezulu ne-chloride corrosion.Ukumelana nokugqwala okuthuthukisiwe kunweba ukusetshenziswa kwe-HDSS ezindaweni ezine-chloride ezinolaka njengezindawo zasolwandle.
Ama-MIC ayinkinga enkulu ezimbonini eziningi ezifana nezimboni zikawoyela negesi nezamanzi14.I-MIC yenza u-20% wawo wonke umonakalo wokugqwala15.I-MIC i-bioelectrochemical corrosion engabonwa ezindaweni eziningi.Ama-biofilms akha ezindaweni zensimbi ashintsha izimo ze-electrochemical, ngaleyo ndlela athinte inqubo yokugqwala.Kukholakala kabanzi ukuthi i-MIC corrosion ibangelwa ama-biofilms.Ama-microorganisms e-electrogenic adla izinsimbi ukuze athole amandla adingekayo ukuze aphile17.Ucwaningo lwakamuva lwe-MIC lubonise ukuthi i-EET (ukudluliselwa kwama-electron angaphandle) iyisici esikhawulela isilinganiso ku-MIC esibangelwa ama-electrogenic microorganisms.UZhang et al.18 ibonise ukuthi abaxhumanisi be-electron basheshisa ukudluliswa kwama-electron phakathi kwamaseli e-Desulfovibrio sessificans kanye nama-304 ensimbi engagqwali, okuholela ekuhlaselweni okunzima kakhulu kwe-MIC.U-Anning et al.19 kanye noWenzlaff et al.20 ibonise ukuthi ama-biofilms we-corrosive sulfate-reducing bacterium (SRBs) angamunca ngokuqondile ama-electron asuka kuma-substrates ensimbi, okuholela ekugobeni okukhulu.
I-DSS yaziwa ukuthi ingenwa kalula yi-MIC kumidiya equkethe ama-SRB, amagciwane e-iron-reducing (IRBs), njll. 21 .Lawa mabhaktheriya abangela umgodi wendawo endaweni ye-DSS ngaphansi kwe-biofilms22,23.Ngokungafani ne-DSS, i-HDSS24 MIC ayaziwa kahle.
I-Pseudomonas aeruginosa iyi-bacterium e-Gram-negative, e-motile, emise okwenduku esatshalaliswa kabanzi emvelweni25.I-Pseudomonas aeruginosa futhi iyiqembu elikhulu le-microbial endaweni yasolwandle, ebangela ukugxila okuphezulu kwe-MIC.I-Pseudomonas ihileleke ngenkuthalo enqubweni yokugqwala futhi ibonakala njengephayona lamakoloni ngesikhathi sokwakheka kwe-biofilm.UMahat et al.28 kanye noYuan et al.29 ibonise ukuthi i-Pseudomonas aeruginosa ithambekele ekukhuphuleni izinga lokugqwala kwensimbi emnene nama-alloys ezindaweni zasemanzini.
Inhloso eyinhloko yalo msebenzi bekuwukuphenya izakhiwo ze-MIC 2707 HDSS ezibangelwa i-marine aerobic bacterium i-Pseudomonas aeruginosa isebenzisa izindlela ze-electrochemical, izindlela zokuhlaziya indawo kanye nokuhlaziywa komkhiqizo wokugqwala.Izifundo ze-Electrochemical, okuhlanganisa amandla wesekethe evulekile (OCP), ukumelana ne-linear polarization (LPR), i-electrochemical impedance spectroscopy (EIS), kanye ne-polarization enamandla, zenziwa ukuze kufundwe ukuziphatha kwe-MIC 2707 HDSS.I-Energy dispersive spectrometric analysis (EDS) yenziwa ukuze kutholwe izakhi zamakhemikhali endaweni egqwalile.Ngaphezu kwalokho, i-X-ray photoelectron spectroscopy (XPS) yasetshenziselwa ukunquma ukuzinza kwefilimu ye-oxide passivation ngaphansi kwethonya lendawo yasolwandle equkethe i-Pseudomonas aeruginosa.Ukujula kwemigodi kukalwe ngaphansi kwe-confocal laser scanning microscope (CLSM).
Ithebula 1 libonisa ukwakheka kwamakhemikhali okungu-2707 HDSS.Ithebula 2 libonisa ukuthi i-2707 HDSS inezakhiwo ezinhle kakhulu zemishini ezinamandla okukhiqiza angu-650 MPa.Emkhiwaneni.1 ikhombisa i-optical microstructure yokushisa kwesixazululo okuphathwe okungu-2707 HDSS.Ku-microstructure equkethe cishe izigaba ze-austenite ezingu-50% kanye ne-50% ye-ferrite, amabhande amade wezigaba ze-austenite ne-ferrite ngaphandle kwezigaba zesibili ziyabonakala.
Emkhiwaneni.I-2a ibonisa amandla esekethe evulekile (Eocp) ngokumelene nesikhathi sokuchayeka se-2707 HDSS ku-2216E abiotic medium kanye nomhluzi we-P. aeruginosa izinsuku ezingu-14 ku-37°C.Kubonisa ukuthi ushintsho olukhulu nolubaluleke kakhulu ku-Eocp lwenzeka phakathi namahora angu-24 okuqala.Amanani we-Eocp kuzo zombili izimo afinyelela umvuthwandaba ongu--145 mV (uma kuqhathaniswa ne-SCE) cishe ngamahora angu-16 abese ehla kakhulu, afinyelela ku--477 mV (uma kuqhathaniswa ne-SCE) kanye -236 mV (uma kuqhathaniswa ne-SCE) ngesampula le-abiotic.kanye namakhuphoni e-P Pseudomonas aeruginosa, ngokulandelana).Ngemva kwamahora angu-24, inani le-Eocp 2707 HDSS le-P. aeruginosa lalizinzile ngokuqhathaniswa kokuthi -228 mV (uma kuqhathaniswa ne-SCE), kuyilapho inani elihambisanayo lamasampuli angewona awebhayoloji lalicishe libe ngu--442 mV (uma kuqhathaniswa ne-SCE).I-Eocp ebukhoneni be-P. aeruginosa yayiphansi kakhulu.
Ucwaningo lwe-Electrochemical lwamasampuli angu-2707 HDSS ku-abiotic medium kanye nomhluzi we-Pseudomonas aeruginosa ku-37 °C:
(a) I-Eocp njengomsebenzi wesikhathi sokuchayeka, (b) ijika le-polarization ngosuku 14, (c) Rp njengomsebenzi wesikhathi sokuchayeka, kanye (d) ne-icorr njengomsebenzi wesikhathi sokuchayeka.
Ithebula lesi-3 libonisa imingcele yokugqwala kwe-electrochemical yamasampula e-HDSS angu-2707 avezwe kumidiya efakwe i-abiotic kanye ne-Pseudomonas aeruginosa esikhathini esiyizinsuku eziyi-14.Ama-tangents we-anode ne-cathode curves akhishwe ukuze athole ukuphambana kwemigwaqo enikeza ukugqwala kwamanje (icorr), amandla okugqwala (Ecorr) kanye nomthambeka we-Tafel (βα no-βc) ngokwezindlela ezijwayelekile30,31.
Njengoba kuboniswe emkhiwaneni.2b, ukushintsha okuya phezulu ku-P. aeruginosa curve kubangele ukwanda kwe-Ecorr uma kuqhathaniswa nejika le-abiotic.Inani le-icorr, elilingana nezinga lokugqwala, lenyuke laya ku-0.328 µA cm-2 kusampula ye-Pseudomonas aeruginosa, enkulu ngokuphindwe kane kunesampula okungeyona eyebhayoloji (0.087 µA cm-2).
I-LPR iyindlela yakudala engacekeli phansi i-electrochemical yokuhlaziya ukugqwala okusheshayo.Iphinde yasetshenziswa ukutadisha i-MIC32.Emkhiwaneni.I-2c ibonisa ukumelana ne-polarization (Rp) njengomsebenzi wesikhathi sokuchayeka.Inani eliphakeme le-Rp lisho ukugqwala okuncane.Phakathi namahora angu-24 okuqala, i-Rp 2707 HDSS ifinyelele u-1955 kΩ cm2 kuma-abiotic specimens kanye no-1429 kΩ cm2 kumasampula e-Pseudomonas aeruginosa.Umfanekiso 2c futhi ubonisa ukuthi inani le-Rp lehle ngokushesha ngemva kosuku olulodwa futhi lahlala lingashintshile uma kuqhathaniswa ezinsukwini eziyi-13 ezilandelayo.Inani le-Rp lesampula le-Pseudomonas aeruginosa licishe libe ngu-40 kΩ cm2, eliphansi kakhulu kunevelu engu-450 kΩ cm2 yesampula okungezona ezebhayoloji.
Inani le-icorr lilingana nezinga lokugqwala elifanayo.Inani layo lingabalwa kusukela kuzibalo ezilandelayo ze-Stern-Giri:
Ngokusho kukaZoe et al.33, inani elijwayelekile lomthambeka we-Tafel B kulo msebenzi lithathwe libe ngu-26 mV/dec.Umfanekiso 2d ubonisa ukuthi i-icorr yesampula okungeyona eyebhayoloji engu-2707 yahlala izinzile, kuyilapho isampula ye-P. aeruginosa yashintshashintsha kakhulu ngemva kwamahora angu-24 okuqala.Amanani e-icorr amasampula e-P. aeruginosa abeyi-oda lobukhulu obuphezulu kunalawo okulawula okungezona ezebhayoloji.Lo mkhuba uhambisana nemiphumela yokumelana ne-polarization.
I-EIS enye indlela engacekeli phansi esetshenziswa ukukhombisa ukusabela kwe-electrochemical ezindaweni ezigqwalile.I-Impedance spectra kanye namanani e-capacitance abaliwe amasampula adalulwe endaweni ye-abiotic kanye nesixazululo se-Pseudomonas aeruginosa, i-passive film/biofilm resistance Rb eyakhiwe endaweni yesampula, ukumelana nokushaja kwe-Rct, i-Cdl ye-double layer capacitance kagesi (EDL) kanye nemingcele yesici se-QCPE engashintshi. (CPE).Le mingcele yabuye yahlaziywa ngokufaka idatha kusetshenziswa imodeli yesekethe elinganayo (EEC).
Emkhiwaneni.3 ibonisa iziza zeNyquist ezijwayelekile (a no-b) kanye neziza ze-Bode (a' no-b') zamasampuli angu-2707 HDSS kumidiya ye-abiotic kanye nomhluzi we-P. aeruginosa ngezikhathi ezihlukene zokufukamela.Ububanzi beringi yeNyquist buyancipha phambi kwe-Pseudomonas aeruginosa.Isakhiwo se-Bode (Fig. 3b') sibonisa ukwanda kwe-impedance ephelele.Ulwazi mayelana nesikhathi sokuphumula esingaguquki lungatholakala ku-phase maxima.Emkhiwaneni.4 ibonisa izakhiwo ezibonakalayo ezisekelwe ku-monolayer (a) kanye ne-bilayer (b) kanye nama-EEC ahambisanayo.I-CPE yethulwa kumodeli ye-EEC.Ukwemukelwa kwayo kanye nokuvinjwa kwayo kuvezwa kanje:
Amamodeli angokwenyama amabili namasekhethi afanayo ahambisanayo wokufaka i-spectrum ye-impedance yesampula 2707 HDSS:
lapho u-Y0 eyinani le-KPI, j inombolo ecatshangelwayo noma (-1)1/2, ω iyi-angular frequency, n inkomba yamandla e-KPI engaphansi kweyodwa35.Ukuguqulwa kokumelana nokudluliswa kweshaji (okungukuthi 1/Rct) kuhambisana nezinga lokugqwala.I-Rct encane, izinga lokugqwala liphezulu27.Ngemuva kwezinsuku eziyi-14 zokufukamela, amasampula e-Rct ye-Pseudomonas aeruginosa afinyelele ku-32 kΩ cm2, okungaphansi kakhulu kwamasampuli angama-489 kΩ cm2 angewona awebhayoloji (Ithebula 4).
Izithombe ze-CLSM nezithombe ze-SEM kumfanekiso wesi-5 zibonisa ngokusobala ukuthi ukumbozwa kwe-biofilm ebusweni besampula ye-HDSS 2707 ngemva kwezinsuku ezingu-7 kuminyene.Kodwa-ke, ngemva kwezinsuku eziyi-14, ukufakwa kwe-biofilm kwaba buthakathaka futhi kwavela amaseli afile.Ithebula lesi-5 libonisa ukushuba kwe-biofilm kumasampuli angu-2707 HDSS ngemva kokuchayeka ku-P. aeruginosa izinsuku ezingu-7 neziyi-14.Ubukhulu obukhulu befilimu ye-biofilm bushintshile ukusuka ku-23.4 µm ngemva kwezinsuku ezingu-7 ukuya ku-18.9 µm ngemva kwezinsuku ezingu-14.Isilinganiso esimaphakathi se-biofilm siphinde saqinisekisa lo mkhuba.Yehla isuka ku-22.2 ± 0.7 μm ngemva kwezinsuku ezingu-7 yaya ku-17.8 ± 1.0 μm ngemva kwezinsuku eziyi-14.
(a) Isithombe se-3-D CLSM ngezinsuku ezingu-7, (b) isithombe se-3-D CLSM ezinsukwini eziyi-14, (c) Isithombe se-SEM ezinsukwini ezingu-7, kanye (d) nesithombe se-SEM ezinsukwini eziyi-14.
I-EMF yembule ama-elementi amakhemikhali ku-biofilms kanye nemikhiqizo yokugqwala kumasampuli avezwe ku-P. aeruginosa izinsuku eziyi-14.Emkhiwaneni.Umfanekiso wesi-6 ubonisa ukuthi okuqukethwe kwe-C, N, O, no-P ku-biofilms nemikhiqizo yokugqwala kuphakeme kakhulu kunezinsimbi ezihlanzekile, njengoba lezi zakhi zihlotshaniswa nama-biofilms kanye nama-metabolites awo.Amagciwane adinga ukulandelela kuphela amanani e-chromium nensimbi.Amazinga aphezulu e-Cr ne-Fe ku-biofilm kanye nemikhiqizo yokugqwala ebusweni bamasampuli abonisa ukuthi i-matrix yensimbi ilahlekelwe izici ngenxa yokugqwala.
Ngemuva kwezinsuku eziyi-14, imigodi ene-P. aeruginosa nangaphandle kwayo yabonwa ku-2216E ephakathi.Ngaphambi kokufaka i-incubation, ingaphezulu lamasampula lalibushelelezi futhi lingenasici (Fig. 7a).Ngemva kokufakwa kanye nokususwa kwemikhiqizo ye-biofilm kanye ne-corrosion, imigodi ejulile ebusweni bamasampuli yahlolwa kusetshenziswa i-CLSM, njengoba kuboniswe ku-Fig. 7b no-c.Akukho mgodi osobala otholakele endaweni yezilawuli ezingezona ezebhayoloji (ubukhulu bokujula komgodi ngu-0.02 µm).Ukujula komgodi okukhulu okudalwe i-P. aeruginosa kube ngu-0.52 µm ngezinsuku ezingu-7 kanye no-0.69 µm ngezinsuku ezingu-14, ngokusekelwe ekujuleni komgodi okumaphakathi okulinganiselwe kusuka kumasampuli angu-3 (ukujula komgodi okukhulu okungu-10 kukhethiwe kusampula ngayinye).Impumelelo engu-0.42 ± 0.12 µm no-0.52 ± 0.15 µm, ngokulandelanayo (Ithebula 5).Lawa manani wokujula kwembobo mancane kodwa abalulekile.
(a) ngaphambi kokuchayeka, (b) izinsuku eziyi-14 endaweni ephilayo, kanye (c) nezinsuku eziyi-14 kumhluzi we-Pseudomonas aeruginosa.
Emkhiwaneni.Ithebula lesi-8 libonisa i-spectra ye-XPS yezindawo ezihlukene zesampula, futhi ukwakheka kwamakhemikhali okuhlaziywe kwendawo ngayinye kufingqiwe kuThebula 6. Kuthebula lesi-6, amaphesenti e-athomu e-Fe ne-Cr ebukhoneni be-P. aeruginosa (amasampuli A no-B) eziphansi kakhulu kunalezo zokulawula okungezona ezebhayoloji.(amasampula C no-D).Kusampula ye-P. aeruginosa, ijika le-spectral ezingeni le-nucleus ye-Cr 2p lifakwe ezingxenyeni ezine eziphezulu ezinamandla abophezelayo (BE) we-574.4, 576.6, 578.3 kanye no-586.8 eV, okungabalulwa ku-Cr, CrO3O3, CrO3, CrO3, CrO3 .kanye ne-Cr(OH)3, ngokulandelana (Fig. 9a kanye no-b).Kumasampuli okungewona awebhayoloji, i-spectrum yeleveli eyinhloko ye-Cr 2p iqukethe iziqongo ezimbili eziyinhloko ze-Cr (573.80 eV ye-BE) ne-Cr2O3 (575.90 eV ye-BE) kumakhiwane.9c kanye no-d, ngokulandelana.Umehluko omangalisa kakhulu phakathi kwamasampuli e-abiotic kanye namasampuli e-P. aeruginosa ubukhona be-Cr6+ nengxenye ehlobene ephakeme ye-Cr(OH)3 (BE 586.8 eV) ngaphansi kwe-biofilm.
I-spectra ebanzi ye-XPS yobuso besampula 2707 HDSS kumidiya emibili yizinsuku eziyi-7 neziyi-14, ngokulandelana.
(a) izinsuku ezingu-7 ukuchayeka ku-P. aeruginosa, (b) izinsuku eziyi-14 zokuchayeka ku-P. aeruginosa, (c) izinsuku ezingu-7 endaweni ye-abiotic, kanye (d) nezinsuku ezingu-14 endaweni ephilayo.
I-HDSS ibonisa izinga eliphezulu lokumelana nokugqwala ezindaweni eziningi.UKim et al.2 ubike ukuthi i-HDSS UNS S32707 ikhonjwe njenge-DSS enengxubevange ephezulu ene-PREN enkulu kunokungu-45. Inani le-PREN lesampula 2707 HDSS kulo msebenzi lalingu-49. Lokhu kungenxa yokuqukethwe okuphezulu kwe-chromium nokuqukethwe okuphezulu kwe i-molybdenum ne-nickel, ewusizo ezindaweni ezine-acidic.kanye nezindawo ezinokuqukethwe okuphezulu kwe-chloride.Ngaphezu kwalokho, ukwakheka okulingana kahle kanye ne-microstructure engenasici kunenzuzo ekuzinzeni kwesakhiwo nokumelana nokugqwala.Kodwa-ke, naphezu kokumelana kwayo okuhle kakhulu namakhemikhali, idatha yokuhlola kulo msebenzi iphakamisa ukuthi i-2707 HDSS ayivikelekile ngokuphelele kuma-MICs e-P. aeruginosa biofilm.
Imiphumela ye-Electrochemical ibonise ukuthi izinga lokugqwala kwe-2707 HDSS ku-P. aeruginosa umhluzi landa kakhulu ngemva kwezinsuku ezingu-14 uma kuqhathaniswa nemvelo engeyona yezinto eziphilayo.Emfanekisweni 2a, ukwehla kwe-Eocp kubonwe kokubili ku-abiotic medium naku-P. aeruginosa umhluzi phakathi namahora angu-24 okuqala.Ngemva kwalokho, i-biofilm ivala ngokuphelele ubuso besampula, futhi i-Eocp iba izinzile ngokuqhathaniswa36.Nokho, izinga le-Eocp lebhayoloji laliphezulu kakhulu kuneleveli ye-Eocp engeyona eyebhayoloji.Kunezizathu zokukholelwa ukuthi lo mehluko uhlotshaniswa nokwakhiwa kwe-P. aeruginosa biofilms.Emkhiwaneni.2d ebukhoneni be-P. aeruginosa, inani le-icorr 2707 HDSS lifinyelele ku-0.627 μA cm-2, okuwuhlelo lobukhulu obungaphezu kokulawulwa kwe-abiotic (0.063 μA cm-2), obuhambisana nenani le-Rct elilinganiselwe nge-EIS.Ezinsukwini ezimbalwa zokuqala, amanani e-impedance kumhluzi we-P. aeruginosa anda ngenxa yokunamathiselwa kwamaseli e-P. aeruginosa kanye nokwakhiwa kwama-biofilms.Kodwa-ke, lapho i-biofilm ihlanganisa ngokuphelele indawo yesampula, i-impedance iyancipha.Isendlalelo sokuzivikela sihlaselwa ngokuyinhloko ngenxa yokwakhiwa kwama-biofilms kanye nama-metabolites e-biofilm.Ngenxa yalokho, ukumelana nokugqwala kwehle ngokuhamba kwesikhathi futhi okunamathiselwe kwe-P. aeruginosa kubangele ukugqwala kwendawo.Amathrendi endaweni ye-abiotic ayehlukile.Ukumelana nokugqwala kokulawulwa okungezona izinto eziphilayo kwakuphakeme kakhulu kunevelu ehambisanayo yamasampuli adalulwe kumhluzi we-P. aeruginosa.Ngaphezu kwalokho, ekungeneni kwe-abiotic, inani le-Rct 2707 HDSS lifinyelele ku-489 kΩ cm2 ngosuku lwe-14, eliphindwe izikhathi ezingu-15 kunevelu ye-Rct (32 kΩ cm2) phambi kwe-P. aeruginosa.Ngakho, i-2707 HDSS inokumelana nokugqwala okuhle kakhulu endaweni eyinyumba, kodwa ayimelani nama-MIC avela ku-P. aeruginosa biofilms.
Le miphumela ingabuye ibonwe kusukela kumajika e-polarization ku-Fig.2b.I-anodic branching ihlotshaniswe ne-Pseudomonas aeruginosa biofilm formation kanye nokusabela kwe-metal oxidation.Kulokhu, ukusabela kwe-cathodic ukuncishiswa kwe-oxygen.Ukuba khona kwe-P. aeruginosa kwandise ngokuphawulekayo ukuminyana kwamanje kokugqwala, mayelana nokuhleleka kobukhulu obuphezulu kunokulawulwa kwe-abiotic.Lokhu kubonisa ukuthi i-P. aeruginosa biofilm ithuthukisa ukugqwala kwasendaweni kwe-2707 HDSS.U-Yuan et al.29 bathole ukuthi ukugqwala kwamanje kokugqwala kwe-Cu-Ni 70/30 alloy kukhuphuke ngaphansi kwesenzo se-P. aeruginosa biofilm.Lokhu kungase kube ngenxa ye-biocatalysis yokunciphisa umoya-mpilo yi-Pseudomonas aeruginosa biofilms.Lokhu kubuka kungase futhi kuchaze i-MIC 2707 HDSS kulo msebenzi.Kungase futhi kube ne-oxygen encane ngaphansi kwe-aerobic biofilms.Ngakho-ke, ukwenqaba ukuphinda kudlule indawo yensimbi nge-oxygen kungase kube isici esinomthelela ku-MIC kulo msebenzi.
Dickinson et al.38 iphakamise ukuthi izinga lokusabela kwamakhemikhali kanye ne-electrochemical lingathinteka ngokuqondile umsebenzi we-metabolic wamabhaktheriya e-sessile endaweni eyisampula kanye nemvelo yemikhiqizo yokugqwala.Njengoba kuboniswe kuMfanekiso 5 kanye neThebula 5, inani lamaseli nokuqina kwe-biofilm kwehle ngemva kwezinsuku eziyi-14.Lokhu kungachazwa ngokunengqondo ukuthi ngemva kwezinsuku ezingu-14, iningi lamaseli e-sessile ebusweni be-2707 HDSS bafa ngenxa yokuncipha kwezakhi ku-2216E medium noma ukukhululwa kwama-ion ensimbi anobuthi ku-matrix ye-2707 HDSS.Lona umkhawulo wokuhlolwa kwenqwaba.
Kulo msebenzi, i-P. aeruginosa biofilm inikele ekuncipheni kwendawo ye-Cr ne-Fe ngaphansi kwe-biofilm ebusweni be-2707 HDSS (Fig. 6).Ithebula lesi-6 libonisa ukuncishiswa kwe-Fe ne-Cr kusampula D uma kuqhathaniswa nesampula C, okubonisa ukuthi i-Fe ne-Cr ehlakaziwe okudalwe i-P. aeruginosa biofilm iqhubeke izinsuku ezingu-7 zokuqala.Imvelo ye-2216E isetshenziselwa ukulingisa imvelo yasolwandle.Iqukethe i-17700 ppm Cl-, eqhathaniswa nokuqukethwe kwayo emanzini emvelo olwandle.Ukuba khona kwe-17700 ppm Cl- kwakuyisizathu esiyinhloko sokuncipha kwe-Cr kumasampuli we-abiotic wezinsuku eziyi-7 neziyi-14 ahlaziywa yi-XPS.Uma kuqhathaniswa namasampula e-P. aeruginosa, ukuhlakazwa kwe-Cr kumasampula e-abiotic bekukuncane kakhulu ngenxa yokumelana okuqinile kwe-2707 HDSS ne-chlorine ngaphansi kwezimo ze-abiotic.Emkhiwaneni.9 ikhombisa ubukhona be-Cr6+ kwifilimu engenzi lutho.Ingase ibandakanyeke ekukhishweni kwe-chromium endaweni yensimbi yi-P. aeruginosa biofilms, njengoba kuphakanyiswe u-Chen no-Clayton.
Ngenxa yokukhula kwamagciwane, amanani e-pH aphakathi ngaphambi nangemuva kokutshala ayengu-7.4 no-8.2, ngokulandelana.Ngakho-ke, ngaphansi kwe-P. aeruginosa biofilm, ukugqwala kwe-asidi ephilayo akulula ukuthi kube neqhaza kulo msebenzi ngenxa ye-pH ephakeme ngokuqhathaniswa endaweni eyinqwaba.I-pH yendawo yokulawula okungeyona eyebhayoloji ayizange ishintshe kakhulu (kusuka ku-7.4 yokuqala ukuya ku-7.5 yokugcina) phakathi nenkathi yokuhlolwa kwezinsuku eziyi-14.Ukwanda kwe-pH endaweni yokujova ngemva kokufukamela kwakuhlotshaniswa nomsebenzi we-metabolic we-P. aeruginosa futhi kwatholakala ukuthi kunomphumela ofanayo ku-pH uma ingekho imicu yokuhlola.
Njengoba kuboniswe kuMfanekiso 7, ukujula komgodi okukhulu okubangwe i-P. aeruginosa biofilm kube ngu-0.69 µm, okungaphezulu kakhulu kwalokho kwe-abiotic medium (0.02 µm).Lokhu kuhambisana nedatha ye-electrochemical echazwe ngenhla.Ukujula komgodi okungu-0.69 µm kuncane ngokuphindwe kashumi kunevelu engu-9.5 µm ebikwe ngo-2205 DSS ngaphansi kwezimo ezifanayo.Le datha ibonisa ukuthi i-2707 HDSS ibonisa ukumelana okungcono kuma-MIC kune-2205 DSS.Lokhu akufanele kusimangaze njengoba i-2707 HDSS inamazinga aphezulu e-Cr anikeza ukudlula okude, okunzima kakhulu ukuvala i-P. aeruginosa, futhi ngenxa yesakhiwo sayo sesigaba esinokulinganisela ngaphandle kwemvula yesibili eyingozi kubangela ukugoba.
Ekuphetheni, imigodi ye-MIC itholwe ebusweni be-2707 HDSS ku-P. aeruginosa broth uma kuqhathaniswa nemigodi engabalulekile endaweni ye-abiotic.Lo msebenzi ubonisa ukuthi i-2707 HDSS inokumelana okungcono ne-MIC kune-2205 DSS, kodwa ayivikelekile ngokuphelele ku-MIC ngenxa ye-P. aeruginosa biofilm.Le miphumela isiza ekukhetheni izinsimbi ezingenasici ezifanele kanye neminyaka yokuphila kwemvelo yasolwandle.
Ikhuphoni le-2707 HDSS linikezwe i-Northeastern University (NEU) School of Metallurgy e-Shenyang, e-China.Ukwakheka okuyisisekelo kwe-2707 HDSS kuboniswa kuThebula 1, elahlaziywa Umnyango Wokuhlaziya Nokuhlola Izinto ze-NEU.Wonke amasampuli aphathwe ngesisombululo esiqinile ku-1180 ° C ihora elingu-1.Ngaphambi kokuhlolwa kokugqwala, i-2707 HDSS emise okwenhlamvu yemali enendawo engaphezulu evulekile engu-1 cm2 yapholishwa yaba amagridi angu-2000 nge-silicon carbide sandpaper yase ipholishwa nge-0.05 µm Al2O3 powder slurry.Izinhlangothi nangaphansi kuvikelwe ngopende ongenayo.Ngemuva kokoma, amasampula ahlanzwa ngamanzi angcolile ahlanjululwe futhi afakwe inzalo nge-ethanol engu-75% (v/v) amahora angu-0.5.Bese zomiswa emoyeni ngaphansi kokukhanya kwe-ultraviolet (UV) amahora angu-0.5 ngaphambi kokusetshenziswa.
I-Marine Pseudomonas aeruginosa strain MCCC 1A00099 yathengwa e-Xiamen Marine Culture Collection Centre (MCCC), e-China.I-Pseudomonas aeruginosa yakhuliswa ngaphansi kwezimo ze-aerobic ku-37° C. kuma-flasks angu-250 ml kanye namaseli e-electrochemical engilazi angu-500 ml kusetshenziswa i-Marine 2216E liquid medium (Qingdao Hope Biotechnology Co., Ltd., Qingdao, China).Okumaphakathi kuqukethe (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 20 203 03Br. 0016 6NH26NH3, 3.0016 NH3 5.0 peptone, 1.0 i-yeast extract kanye ne-0.1 iron citrate.I-Autoclave ku-121 ° C imizuzu engu-20 ngaphambi kokujova.Bala amaseli e-sessile nama-planktonic nge-hemocytometer ngaphansi kwesibonakhulu esikhanyayo ekukhuliseni okungu-400x.Ukuhlushwa kokuqala kwe-planktonic Pseudomonas aeruginosa ngokushesha ngemva kokujova cishe kwakungamaseli angu-106/ml.
Ukuhlolwa kwe-electrochemical kwenziwa esitokisini seglasi le-electrode yakudala enevolumu ephakathi kwama-500 ml.Ishidi leplatinamu kanye ne-saturated calomel electrode (SAE) kuxhunywe ku-reactor ngama-Luggin capillaries agcwele amabhuloho kasawoti, asebenza njengama-counter and reference electrode, ngokulandelana.Ukuze kwenziwe ama-electrode asebenzayo, intambo yethusi eyenziwe ngeraba yaxhunywa kusampula ngayinye futhi yambozwa nge-epoxy resin, ishiya cishe u-1 cm2 wendawo engavikelekile ye-electrode esebenzayo ohlangothini olulodwa.Ngesikhathi sokukalwa kwe-electrochemical, amasampula abekwe endaweni engu-2216E futhi agcinwe ezingeni lokushisa elingaguquki le-incubation (37°C) endaweni yokugeza yamanzi.I-OCP, LPR, EIS kanye nedatha ye-dynamic polarization kwalinganiswa kusetshenziswa i-Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA).Ukuhlolwa kwe-LPR kwarekhodwa ngesilinganiso sokuskena esingu-0.125 mV s-1 ebangeni elingu--5 kuya ku-5 mV nge-Eocp kanye nesilinganiso samasampula esingu-1 Hz.I-EIS yenziwe nge-sine wave ebangeni lemvamisa elingu-0.01 kuye ku-10,000 Hz kusetshenziswa i-voltage esetshenzisiwe engu-5 mV endaweni engashintshi ye-Eocp.Ngaphambi kokushanela okungaba khona, ama-electrode abekwimodi yokungenzi lutho kuze kube yilapho kufinyelelwa inani elizinzile lamandla okugqwala amahhala.Amajika e-polarization abe eselinganiswa ukusuka ku--0.2 kuya ku-1.5 V njengomsebenzi we-EoCP ngesilinganiso sokuskena esingu-0.166 mV/s.Ukuhlolwa ngakunye kwaphindwa izikhathi ezi-3 nge-P. aeruginosa nangaphandle kwayo.
Amasampuli okuhlaziya i-metallographic apholishwa ngomshini ngephepha le-SiC legrit elingu-2000 elimanzi abese epholishwa ngokuqhubekayo ngokumiswa okuyimpushana okungu-0.05 µm Al2O3 ukuze kubonwe ngamehlo.Ukuhlaziywa kwe-metallographic kwenziwa kusetshenziswa isibonakhulu esibonakalayo.Amasampula aqoshwe ngesisombululo esingu-10 wt% se-potassium hydroxide 43.
Ngemva kokufukamela, amasampula ahlanzwa izikhathi ezingu-3 nge-phosphate buffered saline (PBS) (pH 7.4 ± 0.2) bese ehlanganiswa ne-2.5% (v/v) glutaraldehyde amahora angu-10 ukulungisa ama-biofilms.Yabe iphelelwa amanzi nge-ethanol ehlanganisiwe (50%, 60%, 70%, 80%, 90%, 95% kanye no-100% ngevolumu) ngaphambi kokoma komoya.Ekugcineni, ifilimu yegolide ifakwa phezu kwesampula ukuze kuhlinzekwe ukuqhutshwa kokubhekwa kwe-SEM.Izithombe ze-SEM bezigxile ezindaweni ezinamaseli amaningi we-P. aeruginosa ebusweni besampula ngayinye.Yenza ukuhlaziya kwe-EDS ukuze uthole izakhi zamakhemikhali.I-Zeiss confocal laser scanning microscope (CLSM) (LSM 710, Zeiss, Germany) yasetshenziswa ukukala ukujula komgodi.Ukuze ubuke imigodi yokugqwala ngaphansi kwe-biofilm, isampula yokuhlola yaqale yahlanzwa ngokuvumelana ne-Chinese National Standard (CNS) GB/T4334.4-2000 ukuze kukhishwe imikhiqizo yokugqwala kanye ne-biofilm ebusweni besampula yokuhlola.
I-X-ray photoelectron spectroscopy (XPS, ESCALAB250 uhlelo lokuhlaziya indawo, i-Thermo VG, USA) ukuhlaziywa kwenziwa kusetshenziswa umthombo we-X-ray we-monochromatic (umugqa we-Aluminium Kα onamandla angu-1500 eV namandla angu-150 W) ebangeni elibanzi amandla okubopha 0 ngaphansi kwezimo ezijwayelekile zokungu -1350 eV.Izibukeli zokucaca okuphezulu zarekhodwa kusetshenziswa amandla okudlulisela angu-50 eV kanye nesinyathelo esingu-0.2 eV.
Amasampula afakwe ekufukameleni akhishiwe futhi agezwa kahle nge-PBS (pH 7.4 ± 0.2) ku-15 s45.Ukubona ukusebenza kwebhaktheriya kwama-biofilms kumasampuli, ama-biofilms angcoliswa kusetshenziswa i-LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, USA).Ikhithi iqukethe odayi ababili be-fluorescent: udayi we-fluorescent oluhlaza we-SYTO-9 kanye nodayi we-propidium iodide (PI) obomvu we-fluorescent.Ku-CLSM, amachashazi aluhlaza nabomvu ane-fluorescent amelela amaseli aphilayo nafile, ngokulandelana.Ukuze kufakwe amabala, u-1 ml wengxube equkethe u-3 µl we-SYTO-9 no-3 µl wesisombululo se-PI wafukanyelwa imizuzu engu-20 ekamelweni lokushisa (23°C) ebumnyameni.Ngemuva kwalokho, amasampula anamabala ahlolwa kumaza amaza amabili (488 nm kumaseli aphilayo kanye nama-559 nm amaseli afile) kusetshenziswa i-Nikon CLSM apparatus (C2 Plus, Nikon, Japan).Ugqinsi lwe-biofilm lukalwe ngemodi yokuskena ye-3D.
Indlela yokucaphuna lesi sihloko: Li, H. et al.I-Microbial corrosion ye-2707 super duplex stainless steel by Pseudomonas aeruginosa marine biofilm.isayensi.6, 20190. doi: 10.1038/srep20190 (2016).
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