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I-Microbial corrosion (MIC) yingxaki enkulu kumashishini amaninzi, njengoko inokukhokelela kwilahleko enkulu yezoqoqosho.I-Super duplex steel stainless 2707 (2707 HDSS) isetyenziswa kwiindawo zaselwandle ngenxa yokumelana kwayo neekhemikhali.Nangona kunjalo, ukuchasana kwayo ne-MIC akuboniswanga ngokomfuniselo.Olu phononongo luvavanye ukuziphatha kwe-MIC 2707 HDSS ebangelwa yibhaktheriya ye-aerobic yolwandle i-Pseudomonas aeruginosa.Uhlalutyo lwe-Electrochemical lubonise ukuba phambi kwe-Pseudomonas aeruginosa biofilm kwi-medium ye-2216E, utshintsho oluhle kwi-corrosion potential and ukwanda kwe-corrosion current density.Uhlalutyo lwe-X-ray ye-photoelectron spectroscopy (XPS) ibonise ukuhla komxholo we-Cr kumphezulu wesampuli phantsi kwe-biofilm.Uhlalutyo olubonakalayo lwemingxuma lubonise ukuba i-P. aeruginosa biofilm ivelise ubunzulu bomgodi obuyi-0.69 µm ngeentsuku ezili-14 zokufukamela.Nangona oku kuncinci, kubonisa ukuba i-2707 HDSS ayikhuselekanga ngokupheleleyo kwi-MIC ye-P. aeruginosa biofilms.
I-Duplex stainless steels (DSS) isetyenziswa ngokubanzi kumashishini ahlukeneyo ngenxa yokudibanisa okugqibeleleyo kweempawu ezibalaseleyo zoomatshini kunye nokumelana nokubola1,2.Nangona kunjalo, i-pitting yendawo isenzeka kwaye ichaphazela ingqibelelo yale steel3,4.I-DSS ayichasananga ne-microbial corrosion (MIC) 5,6.Nangona uluhlu olubanzi lwezicelo ze-DSS, kusekho iindawo apho ukuxhathisa ukubola kwe-DSS akwanelanga ukusetyenziswa kwexesha elide.Oku kuthetha ukuba kufuneka izixhobo ezibiza kakhulu ezinokumelana nomhlwa.UJeon et al7 ufumanise ukuba kwanezintsimbi ze-duplex ezingenasici (SDSS) zinezithintelo ezithile ngokwemiqathango yokuxhathisa umhlwa.Ke ngoko, kwezinye iimeko, iintsimbi ze-super duplex stainless (HDSS) ezinokumelana nokukhula okuphezulu ziyafuneka.Oku kwakhokelela ekuphuhlisweni kwe-HDSS ene-alloyed kakhulu.
Ukumelana nokubola kwe-DSS kuxhomekeke kumlinganiselo wezigaba ze-alpha kunye ne-gamma kwaye ziphelile kwiindawo ze-Cr, i-Mo kunye ne-W 8, i-9, i-10 kufuphi nesigaba sesibini.I-HDSS iqulethe umxholo ophezulu we-Cr, i-Mo kunye ne-N11, ngoko ke inokumelana ne-corrosion egqwesileyo kunye nexabiso eliphezulu (45-50) lenombolo yokumelana ne-pitting elinganayo (PREN) egqitywe ngu-wt.% Cr + 3.3 (wt.% Mo + 0.5 wt. .%W) + 16% wt.N12.Ukuxhatshazwa kwayo okugqwesileyo kuxhomekeke ekubunjweni kokulinganisela okuqulethe malunga ne-50% ye-ferritic (α) kunye ne-50% ye-austenitic (γ) izigaba.I-HDSS ineempawu ezingcono zoomatshini kunye nokuchasana okuphezulu kwi-chloride corrosion.Ukuphuculwa kokumelana nomhlwa kwandisa ukusetyenziswa kwe-HDSS kwiindawo ezinobundlongondlongo zekloride ezifana neendawo ezihlala elwandle.
Ii-MIC ziyingxaki enkulu kumashishini amaninzi afana ne-oyile negesi nemizi-mveliso yamanzi14.I-MIC yenza i-20% yawo wonke umonakalo owenziwe ngumhlwa15.I-MIC yi-corrosion ye-bioelectrochemical enokubonwa kwiindawo ezininzi.Iifilimu ze-Biofilm ezenza kwiindawo zetsimbi zitshintsha iimeko ze-electrochemical, ngaloo ndlela zichaphazela inkqubo yokubola.Kukholelwa ngokubanzi ukuba i-MIC corrosion yenziwa zii-biofilms.Iimicroorganisms ze-Electrogenic zitya iintsimbi ukuze zifumane amandla eziwadingayo ukuze ziphile17.Uphononongo lwamva nje lwe-MIC lubonise ukuba i-EET (i-extracellular electron transfer) yi-rate-limiting factor in MIC eyenziwa yi-electrogenic microorganisms.UZhang et al.I-18 ibonise ukuba i-electron intermediaries ikhawulezisa ukuhanjiswa kwee-electron phakathi kweeseli ze-Desulfovibrio sessificans kunye ne-304 yensimbi engenasici, okukhokelela kuhlaselo olubi kakhulu lwe-MIC.UAnning et al.19 kunye noWenzlaff et al.I-20 ibonise ukuba i-biofilms ye-corrosive sulfate-reducing bacteria (SRBs) inokufunxa ngokuthe ngqo i-electrons kwii-substrates zetsimbi, okukhokelela kwi-pitting enzima.
I-DSS yaziwa ukuba ichaphazeleka kwi-MIC kumajelo eendaba aqukethe ii-SRBs, iibhaktheriya zokunciphisa isinyithi (IRBs), njl.Ezi bhaktheriya zibangela i-pitting yendawo kumphezulu we-DSS phantsi kwe-biofilms22,23.Ngokungafaniyo ne-DSS, i-HDSS24 MIC ayaziwa kakuhle.
I-Pseudomonas aeruginosa yintsholongwane ye-Gram-negative, eshukumayo, emile okwentonga esasazwe ngokubanzi kwindalo25.I-Pseudomonas aeruginosa ikwalelona qela le-microbial enkulu kwindawo yaselwandle, ebangela ukugxila okuphezulu kwe-MIC.I-Pseudomonas ibandakanyeka ngokusebenzayo kwinkqubo yokubola kwaye yamkelwa njenge-colonizer enguvulindlela ngexesha lokwenziwa kwe-biofilm.UMahat et al.28 kunye Yuan et al.I-29 ibonise ukuba i-Pseudomonas aeruginosa ithambekele ekunyuseni izinga lokubola kwentsimbi epholileyo kunye ne-alloys kwiindawo ezihlala emanzini.
Injongo ephambili yalo msebenzi yayikukuphanda iipropati ze-MIC 2707 HDSS ezibangelwa yibhaktiriya ye-aerobic yolwandle i-Pseudomonas aeruginosa isebenzisa iindlela ze-electrochemical, iindlela zokuhlalutya umphezulu kunye nohlalutyo lwemveliso yokubola.Izifundo ze-Electrochemical, kubandakanywa amandla esekethe evulekileyo (i-OCP), ukuchasana kwe-polarization ye-linear (LPR), i-electrochemical impedance spectroscopy (EIS), kunye ne-polarization enamandla, zenziwa ukufunda ukuziphatha kwe-MIC 2707 HDSS.Uhlalutyo lwe-energy dispersive spectrometric (EDS) lwaqhutyelwa ukukhangela izinto zekhemikhali kumphezulu odlekileyo.Ukongezelela, i-X-ray photoelectron spectroscopy (XPS) yayisetyenziselwa ukumisela ukuzinza kwefilimu ye-oxide passivation phantsi kweempembelelo zendalo yaselwandle equkethe i-Pseudomonas aeruginosa.Ubunzulu bemingxuma bulinganiswe phantsi kwe-confocal laser scanning microscope (CLSM).
Itheyibhile 1 ibonisa ukubunjwa kweekhemikhali ze-2707 HDSS.Itheyibhile ye-2 ibonisa ukuba i-2707 HDSS ineempawu ezibalaseleyo zoomatshini kunye namandla esivuno se-650 MPa.Kwikhiwane.I-1 ibonisa i-microstructure ye-optical yesisombululo sobushushu esiphathwe nge-2707 HDSS.Kwi-microstructure equlethe malunga ne-50% ye-austenite kunye ne-50% yezigaba ze-ferrite, iibhendi ezinde ze-austenite kunye ne-ferrite ngaphandle kwezigaba zesibini ziyabonakala.
Kwikhiwane.I-2a ibonisa amandla esekethe evulekileyo (Eocp) ngokubhekiselele kwixesha lokuvezwa kwe-2707 HDSS kwi-2216E abiotic medium kunye ne-P. aeruginosa umhluzi weentsuku ze-14 kwi-37 ° C.Ibonisa ukuba utshintsho olukhulu nolubalulekileyo kwi-Eocp lwenzeka kwiiyure ezingama-24 zokuqala.Amaxabiso e-Eocp kuzo zombini iimeko aphakamileyo kwi--145 mV (xa kuthelekiswa ne-SCE) malunga ne-16 h kwaye emva koko yehla ngokukhawuleza, ifikelela -477 mV (xa kuthelekiswa ne-SCE) kunye -236 mV (xa kuthelekiswa ne-SCE) yesampuli ye-abiotic.kunye neekhuphoni zeP Pseudomonas aeruginosa, ngokulandelanayo).Emva kweeyure ze-24, ixabiso le-Eocp 2707 HDSS ye-P. aeruginosa yayizinzile kwi--228 mV (xa kuthelekiswa ne-SCE), ngelixa ixabiso elihambelanayo leesampuli ezingezizo zebhayoloji lalimalunga -442 mV (xa kuthelekiswa ne-SCE).I-Eocp kubukho be-P. aeruginosa yayiphantsi kakhulu.
Uphononongo lwe-Electrochemical yeesampulu ze-HDSS ezingama-2707 kwi-abiotic medium kunye ne-Pseudomonas aeruginosa umhluzi kwi-37 °C:
(a) I-Eocp njengomsebenzi wexesha lokuvezwa, (b) iigophe zepolarization ngosuku lwe-14, (c) Rp njengomsebenzi wexesha lokuvezwa, kunye (d) ne-icorr njengomsebenzi wexesha lokuvezwa.
Itheyibhile 3 ibonisa imilinganiselo ye-electrochemical corrosion ye-2707 HDSS iisampulu ezivezwe kwi-abiotic kunye ne-Pseudomonas aeruginosa yeendaba ezifakwe kwi-inoculated kwithuba leentsuku ze-14.I-tangents ye-anode kunye ne-cathode curves yakhutshwa ukuze ifumane i-intersections enika i-corrosion current density (icorr), i-corrosion potential (Ecorr) kunye ne-Tafel slope (βα kunye ne-βc) ngokweendlela eziqhelekileyo30,31.
Njengoko kubonisiwe kwifig.I-2b, ukunyuka okuphezulu kwi-curve ye-P. aeruginosa kubangele ukwanda kwe-Ecorr xa kuthelekiswa ne-abiotic curve.Ixabiso le-icorr, elilingana nezinga lokubola, linyuke laya kutsho kwi-0.328 µA cm-2 kwisampulu ye-Pseudomonas aeruginosa, ephindwe kane kunesampulu engeyoyebhayoloji (0.087 µA cm-2).
I-LPR yindlela yakudala engonakalisi ye-electrochemical yokuhlalutya umhlwa okukhawulezayo.Ikwasetyenziselwa ukufunda i-MIC32.Kwikhiwane.I-2c ibonisa ukuchasana kwe-polarization (Rp) njengomsebenzi wexesha lokuvezwa.Ixabiso eliphezulu le-Rp lithetha ukuthotywa okuncinci.Kwiiyure ezingama-24 zokuqala, i-Rp 2707 HDSS yafikelela kwi-1955 kΩ cm2 kwimizekelo ye-abiotic kunye ne-1429 kΩ cm2 kwisampulu ze-Pseudomonas aeruginosa.Umzobo 2c ubonisa ukuba ixabiso le-Rp lehle ngokukhawuleza emva kosuku olunye kwaye lahlala lingaguqukanga kwiintsuku ze-13 ezilandelayo.Ixabiso le-Rp lesampulu ye-Pseudomonas aeruginosa imalunga ne-40 kΩ cm2, engaphantsi kakhulu kunexabiso le-450 kΩ cm2 yesampulu engeyoyebhayoloji.
Ixabiso le-icorr lilingana nezinga lokutya okufanayo.Ixabiso layo lingabalwa kule equation yeStern-Giri ilandelayo:
Ngokutsho kukaZoe et al.33, ixabiso eliqhelekileyo lethambeka le-Tafel B kulo msebenzi lithathwe libe yi-26 mV/dec.Umzobo we-2d ubonisa ukuba i-icorr yesampula engeyiyo yebhayoloji ye-2707 yahlala izinzile, ngelixa isampuli ye-P. aeruginosa iguquguquka kakhulu emva kweeyure zokuqala ze-24.Amaxabiso e-icorr eisampulu ze-P. aeruginosa ibingumyalelo wobukhulu obuphezulu kunolawulo olungelulo lwebhayoloji.Lo mkhwa uhambelana neziphumo zokumelana ne-polarization.
I-EIS yenye indlela engonakalisiyo esetyenziselwa ukubonakalisa ukusabela kwe-electrochemical kwi-corrod surfaces.Impedance spectra kunye nokubalwa kwamaxabiso eesampulu ezivezwe kwindawo ye-abiotic kunye nesisombululo se-Pseudomonas aeruginosa, ifilimu enganyangekiyo/i-biofilm ukumelana ne-Rb eyenziwe kumphezulu wesampulu, ukuchasa ukuhanjiswa kweRct, umbane ophindwe kabini kwi-Cdl (EDL) kunye neeparamitha zeSigaba seQCPE rhoqo. (CPE).Ezi parameters zahlaziywa ngakumbi ngokufaka idatha kusetyenziswa imodeli yesekethe elinganayo (EEC).
Kwikhiwane.I-3 ibonisa iindawo eziqhelekileyo zeNyquist (a kunye ne-b) kunye neendawo zeBode (a' kunye ne-b') ze-2707 iisampuli ze-HDSS kwi-abiotic media kunye ne-P. aeruginosa umhluzi wamaxesha ahlukeneyo okufukamela.Idayamitha yeringi yeNyquist iyancipha xa kukho iPseudomonas aeruginosa.Isakhiwo seBode (Umfanekiso 3b ') ubonisa ukwanda kwe-impedance epheleleyo.Ulwazi malunga nexesha lokuphumla elingaguqukiyo linokufumaneka kwi-phase maxima.Kwikhiwane.I-4 ibonisa izakhiwo ezibonakalayo ezisekelwe kwi-monolayer (a) kunye ne-bilayer (b) kunye nee-EEC ezihambelanayo.I-CPE yaziswa kwimodeli ye-EEC.Ukwamkelwa kwayo kunye nokuphazamiseka kubonakaliswa ngolu hlobo lulandelayo:
Iimodeli ezimbini zomzimba kunye neesekethe ezilinganayo zokulinganisa i-impedance spectrum yesampuli ye-2707 HDSS:
apho u-Y0 lixabiso le-KPI, j linani lentelekelelo okanye (-1)1/2, ω yi-angular frequency, n sisalathiso samandla e-KPI esingaphantsi kwe-135.I-inversion yokumelana nokudluliselwa kwentlawulo (okt 1 / Rct) ihambelana nezinga lokubola.I-Rct encinci, iphezulu izinga lokutya27.Emva kweentsuku ze-14 zokufukamela, i-Rct ye-Pseudomonas aeruginosa iisampulu ifikelele kwi-32 kΩ cm2, engaphantsi kakhulu kwe-489 kΩ cm2 yeesampuli ezingezona zebhayoloji (Itheyibhile 4).
Imifanekiso ye-CLSM kunye nemifanekiso ye-SEM kwi-Figure 5 ibonisa ngokucacileyo ukuba i-biofilm yokugqoka ebusweni be-HDSS isampuli ye-2707 emva kweentsuku ze-7 inzima.Nangona kunjalo, emva kweentsuku ezili-14, ukukhutshwa kwe-biofilm kwakungalunganga kwaye ezinye iiseli ezifileyo zavela.Itheyibhile yesi-5 ibonisa ubukhulu be-biofilm kwiisampuli ze-2707 HDSS emva kokuvezwa kwi-P. aeruginosa iintsuku ezi-7 kunye ne-14.Ubuninzi bebhayofilm ubukhulu butshintshile ukusuka kwi-23.4 µm emva kweentsuku ezisi-7 ukuya kwi-18.9 µm emva kweentsuku ezili-14.Umndilili wobunzima bebhayofilm nawo ubuqinisekisile lo mkhwa.Yehla ukusuka kwi-22.2 ± 0.7 μm emva kweentsuku ezi-7 ukuya kwi-17.8 ± 1.0 μm emva kweentsuku ezili-14.
(a) Umfanekiso we-3-D CLSM ngeentsuku ezisi-7, (b) umfanekiso we-3-D CLSM ngeentsuku ezili-14, (c) umfanekiso we-SEM ngeentsuku ezisi-7, kunye (d) nomfanekiso we-SEM ngeentsuku ezili-14.
I-EMF iveze izinto zekhemikhali kwi-biofilms kunye neemveliso zomhlwa kwiisampuli ezivezwe kwi-P. aeruginosa iintsuku ezili-14.Kwikhiwane.Umzobo we-6 ubonisa ukuba umxholo we-C, N, O, kunye ne-P kwi-biofilms kunye neemveliso ze-corrosion ziphezulu kakhulu kunezinyithi ezicocekileyo, ekubeni ezi zinto zidibene ne-biofilms kunye ne-metabolites yazo.Iintsholongwane zifuna kuphela isixa sechromium kunye nentsimbi.Amanqanaba aphezulu e-Cr kunye ne-Fe kwi-biofilm kunye neemveliso ze-corrosion kumphezulu weesampuli zibonisa ukuba i-matrix yensimbi ilahlekelwe yizinto ngenxa yokubola.
Emva kweentsuku ezili-14, imingxuma ene-P. aeruginosa nangaphandle kwayo yabonwa phakathi kwe-2216E.Ngaphambi kokufukanyelwa, umphezulu weesampulu wawugudileyo kwaye awunasiphako (umzobo 7a).Emva kokufakwa kunye nokususwa kwe-biofilm kunye neemveliso ze-corrosion, imingxuma enzulu kumphezulu weesampuli zahlolwa kusetyenziswa i-CLSM, njengoko kubonisiwe kwi-Fig. 7b kunye ne-c.Akukho mgodi ucacileyo ufunyenwe kumphezulu wolawulo olungelulo lwebhayoloji (obona nzulu bomgodi yi-0.02 µm).Obona bukhulu bomngxuma ubunzulu obubangelwe yi-P. aeruginosa yi-0.52 µm ngeentsuku ezisi-7 kunye ne-0.69 µm ngeentsuku ezili-14, ngokusekwe kumndilili wobunzulu bomngxuma obuphezulu kwiisampulu ezi-3 (i-10 ubunzulu bomngxuma obona buninzi bakhethwa kwisampulu nganye).Impumelelo ye-0.42 ± 0.12 µm kunye ne-0.52 ± 0.15 µm, ngokulandelanayo (Itheyibhile 5).Ezi xabiso zobunzulu bomngxuma zincinci kodwa zibalulekile.
(a) phambi kokuba sesichengeni, (b) iintsuku ezili-14 kwindawo yendalo ephilayo, kunye (c) neentsuku ezili-14 kwi-Pseudomonas aeruginosa broth.
Kwikhiwane.Itheyibhile 8 ibonisa i-XPS spectra yemigangatho eyahlukeneyo yeesampulu, kunye nokwakheka kweekhemikhali ezihlalutywayo kwindawo nganye kushwankathelwa kwiThebhile 6. KwiThebhile 6, iipesenti ze-athomu ze-Fe kunye ne-Cr kubukho be-P. aeruginosa (iisampulu A kunye ne-B) ezisezantsi kakhulu kunolawulo olungelulo lwebhayoloji.(iisampulu C kunye no-D).Kwisampula ye-P. aeruginosa, i-spectral curve kwinqanaba le-nucleus ye-Cr 2p ifakwe kumacandelo amane aphezulu anamandla okubopha (BE) ye-574.4, 576.6, 578.3 kunye ne-586.8 eV, enokuthi ifakwe kwi-Cr, Cr3O3, CrO3, CrO3 .kunye ne-Cr(OH)3, ngokulandelelanayo (Umfanekiso 9a kunye no-b).Kwiisampuli ezingezizo zebhayoloji, i-spectrum yenqanaba eliphambili le-Cr 2p liqulethe iincopho ezimbini eziphambili ze-Cr (573.80 eV ye-BE) kunye ne-Cr2O3 (575.90 eV ye-BE) kwiiFig.9c kunye no-d, ngokulandelelanayo.Owona mahluko umangalisayo phakathi kweesampulu ze-abiotic kunye neesampulu ze-P. aeruginosa yaba bubukho be-Cr6+ kunye nomlinganiselo ophezulu ozalanayo we-Cr(OH)3 (BE 586.8 eV) phantsi kwe-biofilm.
I-spectra ye-XPS ebanzi yobuso besampula ye-2707 HDSS kwimidiya emibini yi-7 kunye neentsuku ze-14, ngokulandelanayo.
(a) Iintsuku ezisi-7 zokuchanabeka kwi-P. aeruginosa, (b) iintsuku ezili-14 zokuchanabeka kwi-P. aeruginosa, (c) iintsuku ezisi-7 kwindawo ye-abiotic, kunye (d) neentsuku ezili-14 kwindawo ye-abiotic.
I-HDSS ibonisa umgangatho ophezulu wokumelana nokubola kwiindawo ezininzi.UKim et al.2 wabika ukuba i-HDSS UNS S32707 ichongiwe njenge-DSS ene-alloyed kakhulu kunye ne-PREN enkulu kune-45. Ixabiso le-PREN yesampuli ye-2707 HDSS kulo msebenzi yayingu-49. Oku kubangelwa umxholo ophezulu we-chromium kunye nomxholo ophezulu i-molybdenum kunye ne-nickel, eziluncedo kwiindawo ezine-acidic.kunye nokusingqongileyo okunomxholo ophezulu wekloridi.Ukongezelela, ukubunjwa okunokulinganisela kunye ne-microstructure engenasiphako kunenzuzo yokuzinza kwesakhiwo kunye nokumelana nokubola.Nangona kunjalo, nangona i-chemical resistance resistance, idatha yovavanyo kulo msebenzi ibonisa ukuba i-2707 HDSS ayikhuselekanga ngokupheleleyo kwi-P. aeruginosa biofilm MICs.
Iziphumo ze-Electrochemical zibonise ukuba izinga lokubola kwe-2707 HDSS kwi-P. aeruginosa umhluzi wenyuka kakhulu emva kweentsuku ze-14 xa kuthelekiswa nendawo engeyiyo yezinto eziphilayo.Kwi-Figure 2a, ukuncipha kwe-Eocp kwabonwa kokubili kwi-abiotic medium kunye ne-P. aeruginosa umhluzi kwiiyure ezingama-24 zokuqala.Emva koko, i-biofilm igubungela ngokupheleleyo umphezulu wesampuli, kwaye i-Eocp iyazinza36.Nangona kunjalo, inqanaba le-Eocp yebhayoloji laliphezulu kakhulu kunenqanaba le-Eocp engeyiyo eyebhayoloji.Kukho izizathu zokukholelwa ukuba lo mahluko unxulumene nokusekwa kwe-P. aeruginosa biofilms.Kwikhiwane.I-2d phambi kwe-P. aeruginosa, i-icorr 2707 ixabiso le-HDSS lifikelele kwi-0.627 μA cm-2, elingumyalelo wobukhulu obuphezulu kunolawulo lwe-abiotic (0.063 μA cm-2), eyayihambelana nexabiso le-Rct elilinganisiweyo. nge-EIS.Kwiintsuku ezimbalwa zokuqala, ixabiso le-impedance kwi-P. aeruginosa broth liye lanyuka ngenxa yokuncamathela kweeseli ze-P. aeruginosa kunye nokwakhiwa kwee-biofilms.Nangona kunjalo, xa i-biofilm igubungela ngokupheleleyo umphezulu wesampulu, i-impedance iyancipha.Uluhlu olukhuselayo luhlaselwa ngokuyinhloko ngenxa yokubunjwa kwe-biofilms kunye ne-biofilm metabolites.Ngenxa yoko, ukuxhathisa kwe-corrosion yehla ngokuhamba kwexesha kwaye uncamathiselo lwe-P. aeruginosa lubangele ukubola kwendawo.Iindlela zokusingqongileyo ze-abiotic zazahlukile.Ukuxhatshazwa kwe-corrosion ye-non-biological control yayiphezulu kakhulu kunexabiso elihambelanayo leesampuli ezivezwe kwi-P. aeruginosa broth.Ukongeza, kwi-abiotic accessions, ixabiso le-Rct 2707 HDSS lifikelele kwi-489 kΩ cm2 ngosuku lwe-14, eliphindwe ngama-15 ngaphezu kwexabiso le-Rct (32 kΩ cm2) phambi kwe-P. aeruginosa.Ngaloo ndlela, i-2707 HDSS inokumelana ne-corrosion egqwesileyo kwindawo eyinyumba, kodwa ayixhathisi kwi-MICs evela kwi-P. aeruginosa biofilms.
Ezi ziphumo zinokujongwa kwakhona kwi-polarization curves kwiFig.2b.I-Anodic branching iye yadibaniswa ne-Pseudomonas aeruginosa ukubunjwa kwe-biofilm kunye ne-metal oxidation reactions.Kule meko, ukusabela kwe-cathodic kukunciphisa i-oxygen.Ubukho be-P. aeruginosa bandise kakhulu ubuninzi be-corrosion yangoku, malunga nomyalelo wobukhulu obuphezulu kunolawulo lwe-abiotic.Oku kubonisa ukuba i-P. aeruginosa biofilm iphucula i-corrosion yendawo ye-2707 HDSS.U-Yuan et al.29 wafumanisa ukuba ubuninzi be-corrosion yangoku ye-Cu-Ni 70/30 ingxubevange yenyuka phantsi kwesenzo se-P. aeruginosa biofilm.Oku kunokuba ngenxa ye-biocatalysis yokunciphisa i-oksijini nge-Pseudomonas aeruginosa biofilms.Olu qwalaselo lunokucacisa kwakhona i-MIC 2707 HDSS kulo msebenzi.Kusenokubakho ioksijini encinci phantsi kwe-aerobic biofilms.Ngoko ke, ukwala ukuphinda udlulise i-metal surface nge-oksijeni ingaba yinto ebangela i-MIC kulo msebenzi.
UDickinson et al.I-38 icebise ukuba ireyithi yeekhemikhali kunye ne-electrochemical reactions inokuchaphazeleka ngokuthe ngqo ngumsebenzi we-metabolic we-sessile ibhaktiriya kumphezulu wesampulu kunye nohlobo lweemveliso zokubola.Njengoko kuboniswe kwi-Figure 5 kunye neThebhile 5, inani leeseli kunye ne-biofilm ubukhulu behla emva kweentsuku ze-14.Oku kunokuchazwa ngokufanelekileyo kukuba emva kweentsuku ezili-14, uninzi lweeseli ze-sessile kumphezulu we-2707 HDSS zafa ngenxa yokuncipha kwezondlo kwi-2216E medium okanye ukukhutshwa kwee-ion zesinyithi ezinetyhefu kwi-matrix ye-2707 HDSS.Lo ngumda wemifuniselo yebhetshi.
Kulo msebenzi, i-P. aeruginosa biofilm ibe negalelo ekunciphiseni kwendawo ye-Cr kunye ne-Fe phantsi kwe-biofilm ebusweni be-2707 HDSS (Umfanekiso 6).Itheyibhile ye-6 ibonisa ukunciphisa i-Fe kunye ne-Cr kwisampula D xa kuthelekiswa nesampuli C, ebonisa ukuba i-Fe kunye ne-Cr echithiweyo ebangelwa yi-P. aeruginosa biofilm iqhubekile kwiintsuku zokuqala ze-7.Imo engqongileyo ye-2216E isetyenziselwa ukulinganisa imeko-bume yaselwandle.Iqulethe i-17700 ppm Cl-, ethelekiseka nomxholo wayo kumanzi endalo olwandle.Ubukho be-17700 ppm Cl- yayisisizathu esiphambili sokuhla kwe-Cr kwiisampuli ze-abiotic ze-7 kunye ne-14 yeentsuku ezihlalutywe yi-XPS.Xa kuthelekiswa neesampuli ze-P. aeruginosa, ukuchithwa kwe-Cr kwiisampulu ze-abiotic kwakungaphantsi kakhulu ngenxa yokumelana okunamandla kwe-2707 HDSS kwi-chlorine phantsi kweemeko ze-abiotic.Kwikhiwane.I-9 ibonisa ubukho be-Cr6 + kwifilimu edlulayo.Inokubandakanyeka ekukhutshweni kwe-chromium kwiindawo zensimbi nge-P. aeruginosa biofilms, njengoko kucetyiswe nguChen noClayton.
Ngenxa yokukhula kwebhaktheriya, amaxabiso e-pH aphakathi ngaphambi nasemva kokulima ayeyi-7.4 kunye ne-8.2, ngokulandelelanayo.Ngaloo ndlela, ngaphantsi kwe-P. aeruginosa biofilm, i-organic acid corrosion ayinakwenzeka ukuba ibe negalelo kulo msebenzi ngenxa ye-pH ephezulu kwi-bulk medium.I-pH ye-non-biological control medium ayizange itshintshe kakhulu (ukusuka kwi-7.4 yokuqala ukuya kwi-7.5 yokugqibela) ngexesha lovavanyo lweentsuku ezili-14.Ukunyuka kwe-pH kwi-inoculation medium emva kokufakwa kwe-incubation kuhambelana nomsebenzi we-metabolic we-P. aeruginosa kwaye kwafunyaniswa ukuba nefuthe elifanayo kwi-pH ngokungabikho kwemicu yokuvavanya.
Njengoko kubonisiwe kuMfanekiso 7, obona bukhulu bomngxuma ubunzulu obubangelwa yi-P. aeruginosa biofilm yayiyi-0.69 µm, inkulu kakhulu kunobo be-abiotic medium (0.02 µm).Oku kuhambelana nedatha ye-electrochemical echazwe ngasentla.Ubunzulu bomgodi we-0.69 µm bungaphezulu kokuphindwe kashumi encinci kune-9.5 µm ixabiso elibikwe nge-2205 DSS phantsi kweemeko ezifanayo.Ezi datha zibonisa ukuba i-2707 HDSS ibonisa ukuchasana okungcono kwi-MIC kune-2205 DSS.Oku akufuneki kusimangalise kuba i-2707 HDSS inamanqanaba aphezulu e-Cr abonelela ngokudlula ixesha elide, kunzima kakhulu ukukhupha i-P. aeruginosa, kwaye ngenxa yesakhiwo sayo sesigaba esilungeleleneyo ngaphandle kwemvula yesibini eyingozi ibangela ukugoba.
Ukuqukumbela, imigodi ye-MIC ifunyenwe phezu kwe-2707 HDSS kwi-P. aeruginosa broth xa kuthelekiswa nemigodi engabalulekanga kwindawo ye-abiotic.Lo msebenzi ubonisa ukuba i-2707 HDSS inokuchasana okungcono kwi-MIC kune-2205 DSS, kodwa ayikhuselekanga ngokupheleleyo kwi-MIC ngenxa ye-P. aeruginosa biofilm.Ezi ziphumo zinceda ekukhetheni iintsimbi eziziintsimbi ezifanelekileyo kunye neminyaka elindelekileyo yokuphila kwendalo yaselwandle.
Ikhuphoni ye-2707 HDSS enikezelwa yiYunivesithi yaseMntla-mpuma (NEU) yeSikolo seMetallurgy eShenyang, eChina.Ukubunjwa kwe-elemental ye-2707 HDSS kuboniswe kwiThebhile 1, eyahlalutywa yi-NEU yoHlalutyo lweMathiriyeli kunye neSebe loVavanyo.Zonke iisampuli zaphathwa isisombululo esiqinileyo kwi-1180 ° C ngeyure eli-1.Phambi kovavanyo lomhlwa, i-2707 HDSS emile okwengqekembe enendawo ephezulu evulekileyo ye-1 cm2 yapolishwa yaya kutsho kwi-2000 grit nge-silicon carbide sandpaper emva koko yapolishwa nge-0.05 µm Al2O3 powder slurry.Amacala kunye nezantsi zikhuselwe ngepeyinti ye-inert.Emva kokumisa, iisampulu zihlanjwe ngamanzi angcolileyo ahlambulukileyo kwaye zihlanjululwe nge-75% (v / v) ye-ethanol ye-0.5 h.Emva koko zomiswa emoyeni phantsi kokukhanya kwe-ultraviolet (UV) i-0.5 h phambi kokusetyenziswa.
I-Marine Pseudomonas aeruginosa strain MCCC 1A00099 yathengwa kwi-Xiamen Marine Culture Collection Centre (MCCC), China.I-Pseudomonas aeruginosa yakhuliswa phantsi kweemeko ze-aerobic kwi-37 ° C. kwiiflaski ze-250 ml kunye ne-500 ml yeglasi yeeseli ze-electrochemical zisebenzisa i-Marine 2216E liquid medium (Qingdao Hope Biotechnology Co., Ltd., Qingdao, China).Iphakathi iqulethe (g / l): 19.45 I-MGCL2, 3.24 I-NCLL, 0.16 00, 0.16 00, 0.16 thbl, 0.16 00, 0,001 i-yeast extract kunye ne-0.1 ye-citrate yensimbi.I-Autoclave kwi-121 ° C imizuzu engama-20 ngaphambi kokugonywa.Bala i-sessile kunye neeseli zeplanktonic ezine-hemocytometer phantsi kwe-microscope yokukhanya kwi-400x yokukhulisa.Ukuxinwa kokuqala kweplanktonic Pseudomonas aeruginosa ngokukhawuleza emva kokugonywa kwakumalunga neeseli ze-106 / ml.
Iimvavanyo ze-Electrochemical zenziwa kwi-classic yeglasi ye-electrode emithathu kunye nomthamo ophakathi kwe-500 ml.Iphepha leplatinum kunye ne-saturated calomel electrode (SAE) zixhunywe kwi-reactor ngokusebenzisa i-Luggin capillaries ezaliswe ngamabhuloho etyuwa, asebenza njenge-counter and reference electrode, ngokulandelanayo.Ukwenziwa kwee-electrodes ezisebenzayo, ucingo lwe-rubberized copper lufakwe kwisampuli nganye kwaye lugqunywe nge-epoxy resin, lushiya malunga ne-1 cm2 yendawo engakhuselekanga ye-electrode esebenzayo kwelinye icala.Ngexesha lokulinganisa i-electrochemical, iisampuli zifakwe kwi-2216E medium kwaye zigcinwe kwiqondo lokushisa eliqhubekayo (37 ° C) kwindawo yokuhlambela amanzi.I-OCP, i-LPR, i-EIS kunye nedatha ye-polarization enokubakho ilinganiswa kusetyenziswa i-Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA).Iimvavanyo ze-LPR zirekhodwe kwireyithi ye-scan ye-0.125 mV s-1 kuluhlu lwe-5 ukuya kwi-5 mV kunye ne-Eocp kunye nesantya sesampuli ye-1 Hz.I-EIS yenziwa nge-sine wave ngaphaya koluhlu lwamaza e-0.01 ukuya kwi-10,000 Hz kusetyenziswa i-voltage esetyenzisiweyo ye-5 mV kwindawo ezinzileyo ye-Eocp.Ngaphambi kokutshayela okunokwenzeka, i-electrodes yayikwimowudi engasebenziyo de kube ixabiso elizinzileyo le-corrosion potential free lifikelelwe.Iingqungquthela ze-polarization zaye zalinganiswa ukusuka -0.2 ukuya kwi-1.5 V njengomsebenzi we-EoCP kwizinga lokuskena kwe-0.166 mV / s.Uvavanyo ngalunye luphindwe ngamaxesha e-3 kunye nangaphandle kwe-P. aeruginosa.
Iisampulu zohlalutyo lwe-metallographic zapholishwa ngomatshini ngephepha le-SiC legrit elimanzi le-2000 kwaye emva koko yapolishwa nge-0.05 µm Al2O3 yomgubo wokunqunyanyiswa ukuze kuqwalaselwe amehlo.Uhlalutyo lwe-metallographic lwenziwa kusetyenziswa i-microscope ebonakalayo.Iisampuli zifakwe nge-10 wt% isisombululo se-potassium hydroxide 43.
Emva kokufukanyelwa, iisampulu zahlanjwa amaxesha e-3 nge-phosphate buffered saline (PBS) (pH 7.4 ± 0.2) emva koko zilungiswe nge-2.5% (v/v) glutaraldehyde iiyure ezili-10 ukulungisa i-biofilms.Emva koko yachithwa nge-ethanol edibeneyo (50%, 60%, 70%, 80%, 90%, 95% kunye ne-100% ngevolumu) ngaphambi kokumisa umoya.Ekugqibeleni, ifilimu yegolide ifakwe kumphezulu wesampulu ukubonelela nge-conductivity yokujongwa kwe-SEM.Imifanekiso ye-SEM yayigxininise kumabala aneeseli ezininzi ze-P. aeruginosa kumphezulu wesampuli nganye.Yenza uhlalutyo lwe-EDS ukufumana izinto zekhemikhali.I-Zeiss confocal laser scanning microscope (CLSM) (LSM 710, Zeiss, Germany) yasetyenziswa ukulinganisa ubunzulu bomgodi.Ukuqwalasela imigodi ye-corrosion phantsi kwe-biofilm, isampuli yovavanyo yaqala ukucocwa ngokwe-Chinese National Standard (CNS) GB/T4334.4-2000 ukususa iimveliso ze-corrosion kunye ne-biofilm kumphezulu wesampuli yovavanyo.
I-X-ray photoelectron spectroscopy (i-XPS, i-ESCALAB250 inkqubo yohlalutyo lomphezulu, i-Thermo VG, e-USA) uhlalutyo lwenziwa kusetyenziswa umthombo we-X-ray we-monochromatic (umgca we-Aluminium Kα onamandla e-1500 eV kunye namandla e-150 W) kuluhlu olubanzi lwe-X-ray. amandla okubopha 0 phantsi kweemeko eziqhelekileyo ze -1350 eV.I-spectra yesisombululo esiphezulu sirekhodwe kusetyenziswa amandla okuhambisa i-50 eV kunye nesinyathelo se-0.2 eV.
Iisampuli ezifakwe kwi-incubated zisusiwe kwaye zahlanjwa ngobumnene nge-PBS (pH 7.4 ± 0.2) kwi-15 s45.Ukujonga ukusebenza kwebhaktheriya yee-biofilms kwiisampulu, ii-biofilms zangcoliswa kusetyenziswa i-LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, USA).Ikhithi iqulethe iidayi ezimbini ze-fluorescent: I-SYTO-9 ye-fluorescent eluhlaza kunye ne-propidium iodide (PI) idayi ebomvu ye-fluorescent.Kwi-CLSM, amachaphaza aluhlaza kunye nebomvu e-fluorescent amele iiseli eziphilayo nezifileyo, ngokulandelanayo.Ukucoca, i-1 ml yomxube oqulethe i-3 µl ye-SYTO-9 kunye ne-3 µl yesisombululo se-PI yafukanyelwa imizuzu engama-20 kwiqondo lobushushu begumbi (23°C) ebumnyameni.Emva koko, iisampuli ezinamabala zavavanywa kumaza amabini (488 nm kwiiseli eziphilayo kunye ne-559 nm yeeseli ezifileyo) kusetyenziswa i-Nikon CLSM apparatus (C2 Plus, Nikon, Japan).Ubunzima be-biofilm bulinganiswe kwimowudi yokuskena ye-3D.
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