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Ukugqwala kweMicrobial (MIC) yingxaki enkulu kumashishini amaninzi kuba kunokubangela ilahleko enkulu kwezoqoqosho. I-2707 super duplex stainless steel (2707 HDSS) isetyenzisiwe kwiindawo zaselwandle ngenxa yokuxhathisa kwayo kakuhle kweekhemikhali. Nangona kunjalo, ukuxhathisa kwayo kwiMIC akukabonakaliswa ngovavanyo. Kolu phononongo, ukuziphatha kweMIC kwe-2707 HDSS okubangelwe yibhaktiriya ye-aerobic yolwandle iPseudomonas aeruginosa kuphandwe. Uhlalutyo lwe-electrochemical lubonise ukuba phambi kwePseudomonas aeruginosa biofilm kwi-2216E medium, bekukho utshintsho oluhle kwi-corrosion potential kunye nokwanda koxinano lwangoku lokugqwala. Uhlalutyo lwe-X-ray photoelectron spectroscopy (XPS) lubonise ukwehla komxholo weCr kumphezulu wesampuli phantsi kwe-biofilm. Uhlalutyo lwemifanekiso yemigodi lubonise ukuba i-P. aeruginosa biofilm ivelise ubunzulu obukhulu bomngxuma obuyi-0.69 μm ngexesha leentsuku ezili-14 zokufunxa. Nangona oku kuncinci, kubonisa ukuba i-2707 HDSS ayikhuselekanga ngokupheleleyo kwi i-MIC ye-P. aeruginosa biofilms.
Iintsimbi ezi-duplex stainless steels (DSS) zisetyenziswa kakhulu kumashishini ahlukeneyo ngenxa yokudibanisa kwazo okufanelekileyo kweempawu ezibalaseleyo zoomatshini kunye nokumelana nokugqwala1,2. Nangona kunjalo, ukugoba okukwindawo ethile kusenzeka kwaye kuchaphazela ukuthembeka kwale ntsimbi3,4. I-DSS ayimelani nokugqwala kweentsholongwane (MIC)5,6. Nangona kukho uluhlu olubanzi lwezicelo ze-DSS, kusekho iindawo apho ukumelana nokugqwala kwe-DSS kunganelanga ukusetyenziswa ixesha elide. Oku kuthetha ukuba izixhobo ezibiza kakhulu ezinokumelana nokugqwala okuphezulu ziyafuneka. UJeon et al7 bafumanise ukuba neentsimbi ezi-super duplex stainless steels (SDSS) zinemida ethile ngokubhekiselele ekumelaneni nokugqwala. Ke ngoko, iintsimbi ezi-super duplex stainless steels (HDSS) ezinokumelana nokugqwala okuphezulu ziyafuneka kwezinye izicelo. Oku kukhokelele ekuphuhlisweni kwe-HDSS exutywe kakhulu.
Ukumelana nokugqwala kwe-DSS kuxhomekeke kumlinganiselo wezigaba ze-alpha kunye ne-gamma kunye neendawo ezincitshisiweyo ze-Cr, Mo kunye ne-W 8, 9, 10 ezikufutshane nesigaba sesibini. I-HDSS iqulethe umxholo ophezulu we-Cr, Mo kunye ne-N11, ngoko ke inokumelana nokugqwala okugqwesileyo kunye nexabiso eliphezulu (45-50) Ukumelana nokugqwala kwePitting Equivalent Number (PREN), emiselwa yi-wt.% Cr + 3.3 (wt.% Mo + 0.5 wt% W) + 16 wt% N12. Ukumelana kwayo okugqwesileyo kokugqwala kuxhomekeke kulwakhiwo olulinganiselayo oluqulethe malunga ne-50% ferrite (α) kunye ne-50% austenite (γ) phases, i-HDSS ineempawu ezingcono zoomatshini kunye nokumelana okuphezulu kune-DSS13 eqhelekileyo. Iimpawu zokugqwala kwe-chloride. Ukumelana nokugqwala okuphuculweyo kwandisa ukusetyenziswa kwe-HDSS kwiindawo ezigqwala ngakumbi ze-chloride, ezifana neendawo zaselwandle.
Ii-MIC ziyingxaki enkulu kumashishini amaninzi afana neoyile, igesi kunye neenkonzo zamanzi14. I-MIC ibangela i-20% yayo yonke imonakalo yokugqwala15. I-MIC yi-bioelectrochemical corrosion enokubonwa kwiindawo ezininzi. Ii-Biofilms ezikwiindawo zesinyithi zitshintsha iimeko ze-electrochemical, ngaloo ndlela zichaphazela inkqubo yokugqwala. Kukholelwa ngokubanzi ukuba ukugqwala kwe-MIC kubangelwa zii-biofilms. Ii-microorganisms ze-electroogenic zigqwala iintsimbi ukuze zifumane amandla okuxhasa ukusinda17. Izifundo zakutshanje ze-MIC zibonise ukuba i-EET (ukudluliselwa kwee-electron ezingaphandle kweseli) yeyona nto ithintela izinga kwi-MIC ebangelwa zii-microorganisms ze-electrogen. UZhang et al. 18 ubonise ukuba abalamli be-electron bakhawulezisa ukudluliselwa kwee-electron phakathi kweeseli ze-Desulfovibrio sessificans kunye ne-304 stainless steel, nto leyo ekhokelela ekuhlaselweni kwe-MIC okuqatha ngakumbi. U-Enning et al. 19 kunye noVenzlaff et al. 20 babonise ukuba ii-biofilms ze-corrosive sulfate-reducing bacteria (SRB) zinokufunxa ngokuthe ngqo ii-electron kwi-substrates zesinyithi, nto leyo ebangela ukugqwala okukhulu kwemigodi.
I-DSS yaziwa ngokuba sengozini ye-MIC kwiindawo eziqulethe i-SRB, iintsholongwane ezinciphisa intsimbi (IRB), njl. 21. Ezi ntsholongwane zibangela ukuqhekeka kwendawo ethile kwiindawo ze-DSS phantsi kwe-biofilms22,23. Ngokungafaniyo ne-DSS, i-MIC ye-HDSS24 ayaziwa kakuhle.
I-Pseudomonas aeruginosa yintsholongwane eshukumayo enemilo yentonga esasazeke kakhulu kwindalo25. I-Pseudomonas aeruginosa ikwaliqela elikhulu leentsholongwane kwindalo yaselwandle, nto leyo ebangela ukuba i-MIC ibe yintsimbi. I-Pseudomonas ibandakanyeka kakhulu kwiinkqubo zokubola kwaye iqatshelwa njenge-colonizer yokuqala ngexesha lokwenziwa kwe-biofilm. UMahat et al. 28 kunye noYuan et al. 29 babonise ukuba i-Pseudomonas aeruginosa inomdla wokunyusa izinga lokubola kwentsimbi ethambileyo kunye nee-alloys kwiindawo ezinamanzi.
Injongo ephambili yalo msebenzi yayikukuphanda iipropati ze-MIC ze-2707 HDSS ezibangelwa yibhaktiriya ye-aerobic yolwandle i-Pseudomonas aeruginosa kusetyenziswa iindlela ze-electrochemical, iindlela zohlalutyo lomphezulu kunye nohlalutyo lwemveliso yokugqwala. Izifundo ze-electrochemical eziquka i-Open Circuit Potential (OCP), i-Linear Polarization Resistance (LPR), i-Electrochemical Impedance Spectroscopy (EIS), kunye ne-Potential Dynamic Polarization zenziwe ukuze kufundwe ukuziphatha kwe-MIC kwe-2707 HDSS. Uhlalutyo lwe-Energy dispersive spectrometer (EDS) lwenziwe ukuze kufunyanwe izinto zeekhemikhali kumphezulu ogqwalileyo. Ukongeza, uhlalutyo lwe-X-ray photoelectron spectroscopy (XPS) lusetyenzisiwe ukumisela uzinzo lwe-oxide film passivation phantsi kwempembelelo yendawo yolwandle equlethe i-Pseudomonas aeruginosa. Ubunzulu bomngxuma bulinganiswe phantsi kwe-confocal laser scanning microscope (CLSM).
Itheyibhile 1 idwelisa ukwakheka kweekhemikhali ze-2707 HDSS. Itheyibhile 2 ibonisa ukuba i-2707 HDSS ineempawu ezibalaseleyo zoomatshini ezinamandla okuvelisa angama-650 MPa. Umfanekiso 1 ubonisa isakhiwo se-optical microstructure sesisombululo esiphathwe ngobushushu se-2707 HDSS. Iibhendi ezinde zesigaba se-austenite kunye ne-ferrite ngaphandle kwesigaba sesibini zinokubonwa kwisakhiwo se-microstructure esiqulethe malunga ne-50% ye-austenite kunye ne-50% yesigaba se-ferrite.
Umfanekiso 2a ubonisa amandla okuvula isekethe (i-Eocp) xa kuthelekiswa nedatha yexesha lokuvezwa kwe-2707 HDSS kwi-abiotic 2216E medium kunye nomhluzi we-P. aeruginosa iintsuku ezili-14 kwi-37 °C. Ubonisa ukuba utshintsho olukhulu nolubalulekileyo kwi-Eocp lwenzeka kwiiyure ezingama-24 zokuqala. Amaxabiso e-Eocp kuzo zombini iimeko afikelele kwi--145 mV (xa kuthelekiswa ne-SCE) malunga neeyure ezili-16 aze ehle kakhulu, afikelela kwi--477 mV (xa kuthelekiswa ne-SCE) kunye ne--236 mV (xa kuthelekiswa ne-SCE) kwisampulu ye-abiotic kunye ne-P, ngokulandelanayo). Iikhuphoni zePseudomonas aeruginosa, ngokwahlukeneyo. Emva kweeyure ezingama-24, ixabiso le-Eocp le-2707 HDSS ye-P. aeruginosa lalizinzile kwi--228 mV (xa kuthelekiswa ne-SCE), ngelixa ixabiso elihambelanayo leesampuli ezingezizo ezebhayoloji lalimalunga ne--442 mV (xa kuthelekiswa ne-SCE). I-Eocp xa kukho i-P. aeruginosa yayiphantsi kakhulu.
Uvavanyo lwe-electrochemical lweesampuli ze-HDSS ezingama-2707 kwi-abiotic medium kunye nomhluzi we-Pseudomonas aeruginosa kuma-37 °C:
(a) I-Eocp njengomsebenzi wexesha lokuvezwa, (b) ii-polarization curves ngomhla we-14, (c) i-Rp njengomsebenzi wexesha lokuvezwa kunye (d) i-icorr njengomsebenzi wexesha lokuvezwa.
Itheyibhile 3 idwelisa amaxabiso e-electrochemical corrosion parameter 2707 iisampulu ze-HDSS ezivezwe kwi-abiotic medium kunye ne-Pseudomonas aeruginosa efakwe i-inculated medium kangangeentsuku ezili-14. Ii-tangents ze-anodic kunye ne-cathodic curves zahlulwahlulwa ukuze zifike kwiindawo ezidibana kuzo ezivelisa i-corrosion current density (icorr), i-corrosion potential (Ecorr) kunye ne-Tafel slopes (βα kunye ne-βc) ngokweendlela eziqhelekileyo30,31.
Njengoko kubonisiwe kuMfanekiso 2b, ukunyuka kwe-P. aeruginosa curve kubangele ukwanda kwe-Ecorr xa kuthelekiswa ne-abiotic curve. Ixabiso le-icorr, elilingana nesantya sokugqwala, linyuke laya kwi-0.328 μA cm-2 kwisampuli ye-Pseudomonas aeruginosa, ngokuphindwe kane kunesampuli engeyiyo yebhayoloji (0.087 μA cm-2).
I-LPR yindlela ye-electrochemical engaqhelekanga engonakalisiyo yohlalutyo lokugqwala ngokukhawuleza. Ikwasetyenziswe ekufundeni i-MIC32. Umfanekiso 2c ubonisa ukumelana kwe-polarization (Rp) njengomsebenzi wexesha lokuvezwa. Ixabiso eliphezulu le-Rp lithetha ukugqwala okuncinci. Kwiiyure zokuqala ezingama-24, i-Rp ye-2707 HDSS ifikelele kwixabiso eliphezulu le-1955 kΩ cm2 kwiisampuli ze-abiotic kunye ne-1429 kΩ cm2 kwiisampuli ze-Pseudomonas aeruginosa. Umfanekiso 2c ubonisa nokuba ixabiso le-Rp lehle ngokukhawuleza emva kosuku olunye laza lahlala lingatshintshanga kangangeentsuku ezili-13 ezilandelayo. Ixabiso le-Rp lesampuli ye-Pseudomonas aeruginosa limalunga ne-40 kΩ cm2, eliphantsi kakhulu kunexabiso le-450 kΩ cm2 lesampuli engeyiyo yebhayoloji.
Ixabiso le-icorr lilingana nezinga lokugqwala elifanayo. Ixabiso lalo lingabalwa kwi-equation elandelayo yeStern-Geary,
Emva koZou et al. 33, ixabiso eliqhelekileyo le-Tafel slope B kulo msebenzi licingelwa ukuba yi-26 mV/dec. Umfanekiso 2d ubonisa ukuba i-icorr yesampulu ye-2707 engeyiyo yebhayoloji yahlala izinzile, ngelixa isampulu ye-P. aeruginosa yatshintshatshintsha kakhulu emva kweeyure zokuqala ezingama-24. Amaxabiso e-icorr eesampulu ze-P. aeruginosa ayephezulu kakhulu kunezolawulo ezingezizo zebhayoloji. Olu hlobo luhambelana neziphumo zokuxhathisa i-polarization.
I-EIS yenye indlela engonakalisiyo esetyenziselwa ukuchaza iimpendulo ze-electrochemical kwiindawo ezidityanisiweyo. Ii-spectra ze-Impedance kunye ne-calculated capacitance values ​​​​zeesampuli ezivezwe kwi-abiotic media kunye nesisombululo se-Pseudomonas aeruginosa, ukumelana kwe-Rb kwefilimu/i-biofilm engasebenziyo eyenziwe phezu komphezulu wesampuli, ukumelana nokudluliselwa kwetshaja ye-Rct, i-Cdl electric double layer capacitance (EDL) kunye neeparameter ze-QCPE Constant Phase Element (CPE). Ezi parameters zahlalutywa ngakumbi ngokufakela idatha kusetyenziswa imodeli yesekethe elinganayo (EEC).
Umfanekiso 3 ubonisa iiploti eziqhelekileyo zeNyquist (a kunye no-b) kunye neeploti zeBode (a' kunye no-b') zeesampuli ze-HDSS ezingama-2707 kwi-abiotic medium kunye nomhluzi we-P. aeruginosa ngamaxesha ahlukeneyo okufunxa. Ububanzi bendandatho yeNyquist buyancipha xa kukho iPseudomonas aeruginosa. Iploti yeBode (Umfanekiso 3b') ibonisa ukwanda kobukhulu be-impedance iyonke. Ulwazi malunga nexesha lokuphumla lunokubonelelwa yi-phase maxima. Umfanekiso 4 ubonisa izakhiwo zomzimba ezisekwe kwi-monolayer (a) kunye ne-bilayer (b) kunye nee-EEC zazo ezihambelanayo. I-CPE ingeniswa kwimodeli ye-EEC. Ukwamkelwa kwayo kunye ne-impedance zivezwa ngolu hlobo lulandelayo:
Iimodeli ezimbini ezibonakalayo kunye neesekethe ezilinganayo ezifanelekileyo zokufaka i-impedance spectrum yesampuli ye-2707 HDSS:
apho u-Y0 ubukhulu be-CPE, u-j linani elicingelwayo okanye (-1)1/2, u-ω yi-angular frequency, kwaye u-n yi-CPE power index engaphantsi kwe-unit35. I-inverse yokumelana nokudluliselwa kwetshaja (oko kukuthi i-1/Rct) ihambelana nesantya sokugqwala. I-Rct encinci ithetha isantya sokugqwala esikhawulezayo27. Emva kweentsuku ezili-14 zokufukamela, i-Rct yeesampulu zePseudomonas aeruginosa ifikelele kwi-32 kΩ cm2, encinci kakhulu kune-489 kΩ cm2 yeesampulu ezingezizo zebhayoloji (Itheyibhile 4).
Imifanekiso ye-CLSM kunye nemifanekiso ye-SEM kuMfanekiso 5 ibonisa ngokucacileyo ukuba ukugqunywa kwe-biofilm kumphezulu wesampuli ye-2707 HDSS emva kweentsuku ezi-7 kuxinene. Nangona kunjalo, emva kweentsuku ezili-14, ukugqunywa kwe-biofilm kwakuncinci kwaye kwavela ezinye iiseli ezifileyo. Itheyibhile 5 ibonisa ubukhulu be-biofilm kwiisampuli ze-2707 HDSS emva kokuvezwa kwi-P. aeruginosa kangangeentsuku ezi-7 kunye ne-14. Ubukhulu be-biofilm butshintshe ukusuka kwi-23.4 μm emva kweentsuku ezi-7 ukuya kwi-18.9 μm emva kweentsuku ezili-14. Ubukhulu be-biofilm obuqhelekileyo nabo buqinisekisile le ndlela. Yehlile 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 emva kweentsuku ezisi-7, (b) Umfanekiso we-3-D CLSM emva kweentsuku ezili-14, (c) Umfanekiso we-SEM emva kweentsuku ezisi-7 kunye (d) nomfanekiso we-SEM emva kweentsuku ezili-14.
I-EDS ityhile izinto zeekhemikhali kwi-biofilms nakwiimveliso zokugqwala kwiisampuli ezivezwe kwi-P. aeruginosa kangangeentsuku ezili-14. Umfanekiso 6 ubonisa ukuba umxholo we-C, N, O, kunye ne-P kwi-biofilms nakwiimveliso zokugqwala uphezulu kakhulu kunowokwiintsimbi ezingenanto, kuba ezi zinto zinxulunyaniswa ne-biofilms kunye nee-metabolites zazo. Ii-microbes zifuna kuphela izixa ezincinci ze-chromium kunye ne-iron. Amanqanaba aphezulu e-Cr kunye ne-Fe kwi-biofilm kunye neemveliso zokugqwala kumphezulu weesampuli zibonisa ukuba i-metal matrix ilahlekelwe zizinto ngenxa yokugqwala.
Emva kweentsuku ezili-14, kwabonwa imingxuma ene-P. aeruginosa kunye nengenayo kwi-2216E medium. Ngaphambi kokuba i-incubation, umphezulu wesampuli wawugudile kwaye ungenaziphene (Umzobo 7a). Emva kokufakwa kwe-incubation kunye nokususwa kwe-biofilm kunye neemveliso zokugqwala, imingxuma enzulu kumphezulu weesampuli yahlolwa phantsi kwe-CLSM, njengoko kubonisiwe kuMfanekiso 7b kunye no-c. Akukho mingxuma icacileyo efunyenweyo kumphezulu weesampuli zolawulo ezingezizo ezebhayoloji (ubunzulu bomngxuma obuphezulu yi-0.02 μm). Ubunzulu bomngxuma obuphezulu obubangelwe yi-Pseudomonas aeruginosa yayiyi-0.52 μm emva kweentsuku ezisi-7 kunye ne-0.69 μm emva kweentsuku ezili-14, ngokusekelwe kubunzulu bomngxuma obuphakathi beesampuli ezi-3 (amaxabiso aphezulu obunzulu bomngxuma ali-10 akhethwe kwisampuli nganye) afikelele kwi-0.42 ± 0.12 μm kunye ne-0.52 ± 0.15 μm, ngokulandelanayo (Itheyibhile 5). La maxabiso obunzulu bomngxuma mancinci kodwa abalulekile.
(a) Ngaphambi kokuvezwa, (b) iintsuku ezili-14 kwindawo engenabungozi emzimbeni kunye (c) iintsuku ezili-14 kwindawo ene-Pseudomonas aeruginosa broth.
Umfanekiso 8 ubonisa ii-spectra ze-XPS zeendawo ezahlukeneyo zeesampuli, kwaye ukwakheka kweekhemikhali okuhlalutyiweyo kumphezulu ngamnye kushwankathelwe kwiTheyibhile 6. KwiTheyibhile 6, iipesenti ze-athomu ze-Fe kunye ne-Cr xa kukho i-P. aeruginosa (iisampuli A kunye ne-B) zaziphantsi kakhulu kunezo zeesampuli zolawulo ezingezizo ezebhayoloji (iisampuli C kunye ne-D). Kwisampuli ye-P. aeruginosa, i-Cr 2p core-level spectral curve ifakwe kwiindawo ezine ze-peak ezinexabiso le-binding energy (BE) ezingama-574.4, 576.6, 578.3 kunye ne-586.8 eV, ezinokubangelwa yi-Cr, Cr2O3, CrO3 kunye ne-Cr(OH)3, ngokwahlukeneyo (Umzobo 9a kunye no-b). Kwiisampuli ezingezizo ezebhayoloji, i-Cr 2p core-level spectrum ineencopho ezimbini eziphambili ze-Cr (573.80 eV ye-BE) kunye ne-Cr2O3 (575.90 eV ye-BE) kwiTheyibhile 9c kunye no-d, ngokwahlukeneyo. Eyona imangalisayo Umahluko phakathi kweesampuli ze-abiotic kunye ne-P. aeruginosa yayikukubakho kwe-Cr6+ kunye neqhezu eliphezulu le-Cr(OH)3 (BE ye-586.8 eV) phantsi kwe-biofilm.
Iispectra ezibanzi ze-XPS zomphezulu wesampuli ye-2707 HDSS kwezi midiya zimbini ziintsuku ezisi-7 kunye neentsuku ezili-14, ngokulandelelana.
(a) Iintsuku ezisi-7 zokuchatshazelwa yi-P. aeruginosa, (b) Iintsuku ezili-14 zokuchatshazelwa yi-P. aeruginosa, (c) Iintsuku ezisi-7 zokuchatshazelwa yi-abiotic medium kunye (d) Iintsuku ezili-14 zokuchatshazelwa yi-abiotic medium.
I-HDSS ibonisa amanqanaba aphezulu okuxhathisa ukugqwala kwiindawo ezininzi. UKim et al. 2 uxele ukuba i-UNS S32707 HDSS ichazwe njenge-DSS exutywe kakhulu ene-PREN engaphezulu kwama-45. Ixabiso le-PREN lesampuli ye-2707 HDSS kulo msebenzi yayiyi-49. Oku kungenxa yomxholo wayo ophezulu we-chromium kunye namanqanaba aphezulu e-molybdenum kunye ne-Ni, aluncedo kwiindawo ezine-acidic kunye ne-chloride ephezulu. Ukongeza, ukwakheka okulinganisiweyo kakuhle kunye nesakhiwo esingenaziphene ziluncedo ekuzinzeni kwesakhiwo kunye nokuxhathisa ukugqwala. Nangona kunjalo, nangona ixhathisa kakhulu iikhemikhali, idatha yovavanyo kulo msebenzi ibonisa ukuba i-2707 HDSS ayikhuselekanga ngokupheleleyo kwi-MIC ye-P. aeruginosa biofilms.
Iziphumo ze-electrochemical zibonise ukuba izinga lokugqwala kwe-2707 HDSS kumhluzi we-P. aeruginosa lonyuswe kakhulu emva kweentsuku ezili-14 xa kuthelekiswa ne-non-biological medium. KwiMifanekiso 2a, ukuncipha kwe-Eocp kwabonwa kwi-abiotic medium kunye nomhluzi we-P. aeruginosa kwiiyure zokuqala ezingama-24. Emva koko, i-biofilm igqibile ukugubungela umphezulu wesampuli kwaye i-Eocp iba nozinzo.36 Nangona kunjalo, inqanaba le-biological Eocp laliphezulu kakhulu kunelo le-non-biological Eocp. Kukho isizathu sokukholelwa ukuba lo mahluko ubangelwa kukwakheka kwe-biofilm ye-P. aeruginosa. KwiMifanekiso 2d, phambi kwe-P. aeruginosa, ixabiso le-icorr le-2707 HDSS lifikelele kwi-0.627 μA cm-2, elalingumyalelo wobukhulu obuphezulu kunelo lolawulo lwe-abiotic (0.063 μA cm-2), elalihambelana nexabiso le-Rct elilinganiswe yi-EIS. Kwiintsuku ezimbalwa zokuqala, amaxabiso e-impedance Kumhluzi we-P. aeruginosa kwanda ngenxa yokuncamathiselwa kweeseli ze-P. aeruginosa kunye nokwenziwa kwee-biofilms. Nangona kunjalo, xa i-biofilm igubungela ngokupheleleyo umphezulu wesampuli, i-impedance iyancipha. Umaleko okhuselayo uhlaselwa kuqala ngenxa yokwenziwa kwee-biofilms kunye nee-biofilm metabolites. Ke ngoko, ukumelana nokugqwala kwehla ngokuhamba kwexesha, kwaye ukunamathela kwe-P. aeruginosa kubangele ukugqwala kwendawo. Iindlela kwimidiya ye-abiotic zahlukile. Ukuxhathisa kokugqwala kolawulo olungelulo lwebhayoloji kwakuphezulu kakhulu kunexabiso elihambelanayo leesampuli ezivezwe kumhluzi we-P. aeruginosa. Ngaphezu koko, kwiisampuli ze-abiotic, ixabiso le-Rct le-2707 HDSS lifikelele kwi-489 kΩ cm2 ngomhla we-14, elaliphindwe kalishumi elinesihlanu ixabiso le-Rct (32 kΩ cm2) xa kukho i-P. aeruginosa. Ke ngoko, i-2707 HDSS inokumelana nokugqwala okugqwesileyo kwindawo engenazintsholongwane, kodwa ayixhathisi kuhlaselo lwe-MIC yi-P. aeruginosa biofilms.
Ezi ziphumo zinokubonwa nakwii-polarization curves kwiFig. 2b. I-anodic branching ibangelwe kukwakheka kwe-Pseudomonas aeruginosa biofilm kunye neempendulo ze-metal oxidation. Kwangaxeshanye, i-cathodic reaction kukunciphisa i-oxygen. Ubukho be-P. aeruginosa bunyuse kakhulu i-corrosion current density, malunga nomyalelo ophezulu kunolawulo lwe-abiotic. Oku kubonisa ukuba i-P. aeruginosa biofilm inyusa i-localized corrosion ye-2707 HDSS. UYuan et al29 bafumanise ukuba i-corrosion current density ye-70/30 Cu-Ni alloy inyuke phantsi komngeni we-P. aeruginosa biofilm. Oku kusenokuba kungenxa ye-biocatalysis yokunciphisa i-oxygen yi-Pseudomonas aeruginosa biofilms. Olu qwalaselo lunokuchaza ne-MIC ye-2707 HDSS kulo msebenzi. Ii-aerobic biofilms zinokuba ne-oxygen encinci phantsi kwazo. Ke ngoko, ukungaphumeleli ukuphinda kudlulise umphezulu wesinyithi yi-oxygen kunokuba yinto enegalelo kwi-MIC kulo msebenzi.
UDickinson et al. 38 bacebise ukuba amazinga eempendulo zeekhemikhali kunye nee-electrochemical anokuchaphazeleka ngokuthe ngqo ngumsebenzi we-metabolic weebhaktheriya ze-sessile kumphezulu wesampuli kunye nohlobo lweemveliso zokugqwala. Njengoko kubonisiwe kuMfanekiso 5 kunye neTheyibhile 5, zombini inani leeseli kunye nobukhulu be-biofilm buyehla emva kweentsuku ezili-14. Oku kunokuchazwa ngokufanelekileyo ukuba emva kweentsuku ezili-14, uninzi lweeseli ze-sessile kumphezulu we-2707 HDSS zafa ngenxa yokuphela kwezondlo kwi-2216E medium okanye ukukhululwa kwee-ion zesinyithi ezinobuthi kwi-2707 HDSS matrix. Oku kungumda wovavanyo lwebatch.
Kulo msebenzi, i-biofilm ye-P. aeruginosa ikhuthaze ukuncipha kwe-Cr kunye ne-Fe phantsi kwe-biofilm kumphezulu we-2707 HDSS (Umzobo 6). KwiTheyibhile 6, ukuncipha kwe-Fe kunye ne-Cr kwisampulu D xa kuthelekiswa nesampulu C, nto leyo ebonisa ukuba i-Fe kunye ne-Cr ezinyibilikisiweyo ezibangelwe yi-P. aeruginosa biofilm ziqhubeke ngaphaya kweentsuku ezi-7 zokuqala. I-medium ye-2216E isetyenziselwa ukulinganisa iindawo zaselwandle. Iqulethe i-17700 ppm Cl-, efana naleyo ifumaneka emanzini olwandle endalo. Ubukho be-17700 ppm Cl- yayiyeyona sizathu siphambili sokuncipha kwe-Cr kwiisampulu ze-abiotic zeentsuku ezi-7 kunye ne-14 ezihlalutywe yi-XPS. Xa kuthelekiswa neesampulu ze-P. aeruginosa, ukuchithwa kwe-Cr kwiisampulu ze-abiotic bekuncinci kakhulu ngenxa yokumelana okunamandla kwe-Cl− kwe-2707 HDSS kwiindawo ze-abiotic. Umfanekiso 9 ubonisa ubukho be-Cr6+ kwifilimu yokungashukumi. Isenokuba negalelo ekususweni kwe-Cr kwiindawo zentsimbi yi-P. ii-biofilms ze-aeruginosa, njengoko kucetyisiwe nguChen noClayton.
Ngenxa yokukhula kweebhaktheriya, amaxabiso e-pH yesixhobo ngaphambi nasemva kokulima ayeyi-7.4 kunye ne-8.2, ngokulandelelana. Ke ngoko, ngaphantsi kwe-P. aeruginosa biofilm, ukubola kwe-organic acid akunakwenzeka ukuba kube yinto enegalelo kulo msebenzi ngenxa ye-pH ephezulu kwisixhobo esikhulu. I-pH yesixhobo sokulawula esingesiso sebhayoloji ayizange itshintshe kakhulu (ukusuka kwi-7.4 yokuqala ukuya kwi-7.5 yokugqibela) ngexesha lovavanyo lweentsuku ezili-14. Ukwanda kwe-pH kwisixhobo sokufaka i-incubation emva kokufakwa kwe-incubation kwakubangelwa ngumsebenzi we-metabolic we-P. aeruginosa kwaye kwafunyaniswa ukuba kunefuthe elifanayo kwi-pH xa kungekho migca yovavanyo.
Njengoko kubonisiwe kuMfanekiso 7, ubunzulu bomngxuma obuphezulu obubangelwe yi-P. aeruginosa biofilm yayiyi-0.69 μm, eyayinkulu kakhulu kuneyo ye-abiotic medium (0.02 μm). Oku kuhambelana nedatha ye-electrochemical echazwe apha ngasentla. Ubunzulu bomngxuma obuyi-0.69 μm buncinci ngokuphindwe kalishumi kunexabiso le-9.5 μm elixelwe kwi-2205 DSS phantsi kweemeko ezifanayo. Ezi datha zibonisa ukuba i-2707 HDSS ibonisa ukumelana okungcono kwe-MIC xa kuthelekiswa ne-2205 DSS. Oku akufanele kumangalise, njengoko i-2707 HDSS inomxholo ophezulu we-chromium, obonelela nge-passivation ehlala ixesha elide, ngenxa yesakhiwo sesigaba esilinganayo ngaphandle kwe-precipitates eyingozi yesibini, okwenza kube nzima kwi-P. aeruginosa ukuba i-depassivate kunye ne-start points eclipse.
Ukuqukumbela, i-MIC pitting ifunyenwe kumphezulu we-2707 HDSS kumhluzi we-P. aeruginosa xa kuthelekiswa ne-pitting engabonakaliyo kwi-abiotic media. Lo msebenzi ubonisa ukuba i-2707 HDSS inokumelana okungcono kwe-MIC kune-2205 DSS, kodwa ayikhuselekanga ngokupheleleyo kwi-MIC ngenxa ye-P. aeruginosa biofilm. Ezi ziphumo zinceda ekukhetheni iintsimbi ezingenasici ezifanelekileyo kunye nobomi benkonzo obuqikelelweyo kwindawo yolwandle.
Ikhuphoni ye-2707 HDSS ibonelelwa yiSikolo seMetallurgy kwiYunivesithi yaseNortheastern (NEU) eShenyang, eTshayina. Ulwakhiwo lwe-2707 HDSS luboniswe kwiTheyibhile 1, eyahlalutywa yiSebe le-NEU Materials Analysis and Testing. Zonke iisampulu zanyangwa kwi-1180 °C kangangeyure e-1. Ngaphambi kovavanyo lokugqwala, i-2707 HDSS enesimo seengqekembe enommandla ophezulu ovezwe ngaphezulu we-1 cm2 yapholishwa ukuya kwi-2000 grit ngephepha le-silicon carbide yaze yapholishwa ngakumbi nge-0.05 μm Al2O3 powder suspension. Amacala kunye nasezantsi akhuselwe yipeyinti engafakwanga. Emva kokomiswa, iisampulu zahlanjwa ngamanzi acocekileyo kwaye zapholishwa nge-75% (v/v) ethanol kangangeeyure eziyi-0.5. Emva koko zomiswa emoyeni phantsi kokukhanya kwe-ultraviolet (UV) kangangeeyure eziyi-0.5 ngaphambi kokusetyenziswa.
Uhlobo lweMarine Pseudomonas aeruginosa MCCC 1A00099 luthengwe kwiXiamen Marine Culture Collection Center (MCCC), eTshayina. I-Pseudomonas aeruginosa ikhuliswe nge-aerobic kwi-37°C kwiiflasks ezingama-250 ml kunye neeseli zeglasi ze-electrochemical ezingama-500 ml kusetyenziswa iMarine 2216E liquid medium (Qingdao Hope Biotechnology Co., Ltd., eQingdao, eTshayina). Phakathi (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 SrBr2, 0.022 H3BO3, 0.004 NaSiO3, 0016 NH3, 0016 NH3, 0016 NaH2PO4 , 5.0 peptone, 1.0 yeast extract kunye ne-0.1 ferric citrate. Zifake kwi-121°C imizuzu engama-20 ngaphambi kokugonywa. Bala iiseli ze-sessile kunye ne-planktonic usebenzisa i-hemocytometer phantsi kwe-microscope ekhanyayo kwi-400X magnification. Uxinzelelo lokuqala lweeseli ze-planktonic Pseudomonas aeruginosa emva nje kokugonywa lwalumalunga ne-106 cells/ml.
Uvavanyo lwe-electrochemical lwenziwe kwiseli yeglasi ye-electrode ezintathu eqhelekileyo enomthamo ophakathi we-500 ml. Iphepha leplatinum kunye ne-electrode ye-calomel eyomeleleyo (SCE) ziqhagamshelwe kwi-reactor nge-capillaries zeLuggin ezizaliswe ziibridges zetyuwa, ezisebenza njengee-electrodes ezichaseneyo kunye nezereferensi, ngokwahlukeneyo. Ukwenza ii-electrodes ezisebenzayo, ucingo lobhedu olugqunywe ngerabha luqhotyoshelwe kwisampuli nganye kwaye lugqunywe nge-epoxy, kwasala malunga ne-1 cm2 yendawo yomphezulu evezwe kwicala elinye kwi-electrode esebenzayo. Ngexesha lokulinganisa i-electrochemical, iisampulu zabekwa kwi-2216E medium kwaye zigcinwe kubushushu obuhlala buhleli (37 °C) kwindawo yokuhlambela amanzi. Idatha ye-OCP, i-LPR, i-EIS kunye nedatha ye-polarization enokubakho ilinganiswe kusetyenziswa i-Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA). Uvavanyo lwe-LPR lurekhodwe ngesantya sokuskena se-0.125 mV s-1 kuluhlu lwe--5 kunye ne-5 mV nge-Eocp kunye ne-sampling frequency ye-1 Hz. I-EIS yenziwe nge-sine wave kuluhlu lwe-frequency. I-0.01 ukuya kwi-10,000 Hz kusetyenziswa i-voltage esetyenzisiweyo ye-5 mV kwi-Eocp ezinzileyo. Ngaphambi kokuba i-potential sweep, ii-electrode zazikwimo ye-open-circuit de kufikelelwe kwixabiso le-stable free corrosion potential. Ii-Polarization curves zaqala ukusuka kwi--0.2 ukuya kwi-1.5 V ngokuchasene ne-Eocp ngesantya se-scan se-0.166 mV/s. Uvavanyo ngalunye luphindwe kathathu nge-P. aeruginosa nangaphandle kwayo.
Iisampuli zohlalutyo lwe-metallographic zicoliwe ngoomatshini ngephepha le-SiC elimanzi elingama-2000 grit zaze zacoliwe ngakumbi nge-0.05 μm Al2O3 powder suspension ukuze zijongwe ngamehlo. Uhlalutyo lwe-metallographic lwenziwe kusetyenziswa i-optical microscope. Iisampuli zicoliwe ngesisombululo se-potassium hydroxide se-10 wt.% 43.
Emva kokufunxa, iisampulu zahlanjwa izihlandlo ezi-3 ngesisombululo se-phosphate-buffered saline (PBS) (pH 7.4 ± 0.2) zaze zalungiswa nge-2.5% (v/v) glutaraldehyde kangangeeyure ezili-10 ukulungisa ii-biofilms. Emva koko zacinywa ngothotho olulinganisiweyo (50%, 60%, 70%, 80%, 90%, 95% kunye ne-100% v/v) ye-ethanol ngaphambi kokuba yomiswe emoyeni. Okokugqibela, umphezulu wesampulu utshizwa ngefilimu yegolide ukubonelela ngokuqhuba kombane ukuze kujongwe i-SEM. Imifanekiso ye-SEM igxile kwiindawo ezineeseli ze-P. aeruginosa ezithambileyo kumphezulu wesampuli nganye. Yenza uhlalutyo lwe-EDS ukuze ufumane izinto zeekhemikhali. I-Zeiss Confocal Laser Scanning Microscope (CLSM) (LSM 710, Zeiss, eJamani) yasetyenziswa ukulinganisa ubunzulu bomngxuma. Ukuze kujongwe imingxuma yokugqwala phantsi kwe-biofilm, isiqwenga sovavanyo saqala sacocwa ngokwe- I-Chinese National Standard (CNS) GB/T4334.4-2000 yokususa iimveliso zokugqwala kunye ne-biofilm kumphezulu wento yovavanyo.
Uhlalutyo lwe-X-ray photoelectron spectroscopy (i-XPS, inkqubo yohlalutyo lomphezulu we-ESCALAB250, i-Thermo VG, e-USA) lwenziwe kusetyenziswa umthombo we-X-ray we-monochromatic (umgca we-aluminium Kα kumandla e-1500 eV kunye namandla e-150 W) kuluhlu olubanzi lwamandla okubopha oluyi-0 phantsi kweemeko eziqhelekileyo -1350 eV. Ii-spectra ezinesisombululo esiphezulu zirekhodwe kusetyenziswa amandla okudlula e-50 eV kunye nobukhulu besinyathelo se-0.2 eV.
Iisampuli ezifakwe kwi-incubation zisusiwe zaza zahlanjwa ngobunono nge-PBS (pH 7.4 ± 0.2) kangange-15 s45. Ukujonga ukuphila kweebhayofilms kwiisampuli, iibhayofilms zafakwa idayi kusetyenziswa i-LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, USA). Le khithi inedayi ezimbini ze-fluorescent, idayi eluhlaza ye-SYTO-9 kunye nedayi ebomvu ye-fluorescent propidium iodide (PI). Phantsi kwe-CLSM, amachaphaza anombala oluhlaza nobomvu amele iiseli eziphilayo nezifileyo, ngokwahlukeneyo. Ukufaka idayi, umxube we-1 ml oqulethe isisombululo se-3 μl SYTO-9 kunye ne-3 μl PI wafakwa kwi-incubation imizuzu engama-20 kubushushu begumbi (23 oC) ebumnyameni. Emva koko, iisampuli ezifakwe kwi-incubation zabonwa kwii-wavelengths ezimbini (488 nm kwiiseli eziphilayo kunye ne-559 nm kwiiseli ezifileyo) kusetyenziswa umatshini we-Nikon CLSM (C2 Plus, Nikon, Japan). Ubukhulu be-Biofilm bulinganiswe kwi Imo yokuskena ye-3-D.
Indlela yokucaphula eli nqaku: Li, H. et al. Ukubola kwe-microbial ye-2707 super duplex stainless steel yi-marine Pseudomonas aeruginosa biofilm.science.Rep. 6, 20190; doi: 10.1038/srep20190 (2016).
UZanotto, F., uGrassi, V., uBalbo, A., uMonticelli, C. kunye noZucchi, F. Ukuqhekeka koxinzelelo lokubola kwentsimbi engagqwali ye-LDX 2101 duplex kwisisombululo se-chloride xa kukho i-thiosulfate.coros.science.80, 205–212 (2014).
UKim, ST, Jang, SH, Lee, IS & Park, YS Isiphumo sonyango lobushushu besisombululo kunye ne-nitrogen kwigesi yokukhusela ekuchaseni ukugqwala kwe-welds ye-super duplex stainless steel welds.coros.science.53, 1939–1947 (2011).
Shi, X., Avci, R., Geiser, M. kunye noLewandowski, Z. Uphononongo lweeKhemikhali zokuthelekisa ukubola kwePitting ebangelwa ziiMicrobial kunye neeElectrochemically kwi-316L Stainless Steel.coros.science.45, 2577–2595 (2003).
ULuo, H., uDong, uCF, uLi, uXG kunye noXiao, K. Ukuziphatha kwe-electrochemical yentsimbi engagqwali ye-2205 duplex kwizisombululo ze-alkaline ze-pH eyahlukileyo xa kukho i-chloride. I-Electrochim.Journal.64, 211–220 (2012).
Little, BJ, Lee, JS kunye noRay, RI Impembelelo ye-biofilms zaselwandle ekugqwaleni: uphononongo olufutshane. Electrochim.Journal.54, 2-7 (2008).