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Ukugqwala kwama-microbial (MIC) kuyinkinga enkulu ezimbonini eziningi njengoba kungabangela ukulahlekelwa okukhulu kwezomnotho. I-2707 super duplex stainless steel (2707 HDSS) isetshenziswe ezindaweni zasolwandle ngenxa yokumelana kwayo okuhle kwamakhemikhali. Kodwa-ke, ukumelana kwayo ne-MIC akukaboniswa ngokuhlola. Kulolu cwaningo, ukuziphatha kwe-MIC kwe-2707 HDSS okubangelwa yi-bacterium ye-aerobic yasolwandle i-Pseudomonas aeruginosa kuhlolwe. Ukuhlaziywa kwe-electrochemical kubonise ukuthi lapho kukhona i-Pseudomonas aeruginosa biofilm ku-2216E medium, kwaba noshintsho oluhle emandleni okugqwala kanye nokwanda kobuningi bamanje okugqwala. Ukuhlaziywa kwe-X-ray photoelectron spectroscopy (XPS) kubonise ukwehla kokuqukethwe kwe-Cr ebusweni besampula ngaphansi kwe-biofilm. Ukuhlaziywa kwezithombe zemigodi kubonise ukuthi i-P. aeruginosa biofilm ikhiqize ukujula okuphezulu komgodi okungu-0.69 μm phakathi nezinsuku ezingu-14 zokufukamela. Nakuba lokhu kuncane, kubonisa ukuthi i-2707 HDSS ayivikelekile ngokuphelele ku- i-MIC ye-biofilms ye-P. aeruginosa.
Izinsimbi ezingenalutho eziphindwe kabili (i-DSS) zisetshenziswa kabanzi ezimbonini ezahlukahlukene ngenxa yenhlanganisela yazo efanele yezakhiwo ezinhle kakhulu zemishini kanye nokumelana nokugqwala1,2. Kodwa-ke, ukufakwa kwemigodi endaweni ethile kusenzeka futhi kuthinta ubuqotho bale nsimbi3,4. I-DSS ayimelani nokugqwala kwamagciwane (i-MIC)5,6.Naphezu kokusetshenziswa okubanzi kwe-DSS, kusenezindawo lapho ukumelana nokugqwala kwe-DSS kunganele ukusetshenziswa kwesikhathi eside.Lokhu kusho ukuthi izinto ezibiza kakhulu ezinokumelana nokugqwala okuphezulu ziyadingeka.UJeon nabanye7 bathole ukuthi ngisho nezinsimbi ezingenalutho eziphindwe kabili (i-SDSS) zinemikhawulo ethile maqondana nokumelana nokugqwala.Ngakho-ke, izinsimbi ezingenalutho eziphindwe kabili (i-HDSS) ezinokumelana nokugqwala okuphezulu ziyadingeka kwezinye izinhlelo zokusebenza.Lokhu kwaholela ekuthuthukisweni kwe-HDSS exutshwe kakhulu.
Ukumelana nokugqwala kwe-DSS kuncike esilinganisweni sezigaba ze-alpha ne-gamma kanye nezindawo ezincishisiwe ze-Cr, Mo kanye ne-W 8, 9, 10 eduze kwesigaba sesibili. I-HDSS iqukethe okuqukethwe okuphezulu kwe-Cr, Mo kanye ne-N11, ngakho-ke inokumelana okuhle kakhulu nokugqwala kanye nenani eliphakeme (45-50) Ukumelana Nokugoba Inombolo Elinganayo (PREN), enqunywa yi-wt.% Cr + 3.3 (wt.% Mo + 0.5 wt% W) + 16 wt% N12. Ukumelana kwayo okuhle kakhulu nokugqwala kuncike ekwakhiweni okulinganiselayo okuqukethe cishe izigaba ze-ferrite (α) ezingama-50% kanye ne-austenite (γ), i-HDSS inezakhiwo ezingcono zemishini kanye nokumelana okuphezulu kune-DSS13 evamile. Izakhiwo zokugqwala kwe-chloride. Ukumelana okuthuthukisiwe kokugqwala kwandisa ukusetshenziswa kwe-HDSS ezindaweni ezigqwala kakhulu ze-chloride, njengezindaweni zasolwandle.
Ama-MIC ayinkinga enkulu ezimbonini eziningi ezifana nezinsiza zikawoyela negesi kanye namanzi14. I-MIC ibangela u-20% wawo wonke umonakalo wokugqwala15. I-MIC iwukugqwala kwe-bioelectrochemical okungabonakala ezindaweni eziningi. Ama-biofilms akheka ezindaweni zensimbi ashintsha izimo ze-electrochemical, ngaleyo ndlela athinta inqubo yokugqwala. Kukholelwa kabanzi ukuthi ukugqwala kwe-MIC kubangelwa ama-biofilms. Ama-microorganisms e-electroogenic agqwala izinsimbi ukuze athole amandla asekelayo ukuze asinde17. Izifundo zakamuva ze-MIC zikhombisile ukuthi i-EET (ukudluliselwa kwe-electron yangaphandle) iyisici esikhawulela izinga ku-MIC esibangelwa ama-microorganisms e-electrogen. UZhang et al. 18 ukhombisile ukuthi abalamuli be-electron basheshisa ukudluliselwa kwe-electron phakathi kwamaseli e-Desulfovibrio sessificans kanye nensimbi engagqwali engu-304, okuholela ekuhlaselweni kwe-MIC okunzima kakhulu. U-Enning et al. 19 kanye noVenzlaff et al. 20 bakhombisile ukuthi ama-biofilms e-corrosive sulfate-reducing bacteria (SRB) angamunca ngqo ama-electron avela kuma-substrates ensimbi, okuholela ekugqwaleni okukhulu kwemigodi.
I-DSS yaziwa ukuthi isengozini ye-MIC ezindaweni eziqukethe i-SRB, amabhaktheriya anciphisa insimbi (i-IRB), njll. 21. Lawa mabhaktheriya abangela ukugoba kwendawo ezindaweni ze-DSS ngaphansi kwe-biofilms22,23. Ngokungafani ne-DSS, i-MIC ye-HDSS24 ayaziwa kahle.
I-Pseudomonas aeruginosa iyigciwane elihambayo elinomumo wenduku elifana ne-gram-negative elisakazeke kabanzi emvelweni25. I-Pseudomonas aeruginosa nayo iyiqembu elikhulu lamagciwane endaweni yasolwandle, okubangela i-MIC ibe yinsimbi. I-Pseudomonas ihileleke kakhulu ezinqubweni zokugqwala futhi yaziwa njenge-colonizer yokuqala ngesikhathi sokwakheka kwe-biofilm. UMahat et al. 28 noYuan et al. 29 babonise ukuthi i-Pseudomonas aeruginosa inomkhuba wokwandisa izinga lokugqwala kwensimbi emnene kanye nama-alloy ezindaweni ezinamanzi.
Inhloso eyinhloko yalo msebenzi kwakuwukuphenya izakhiwo ze-MIC ze-2707 HDSS ezibangelwa yi-bacterium ye-aerobic yasolwandle i-Pseudomonas aeruginosa kusetshenziswa izindlela ze-electrochemical, amasu okuhlaziya ubuso kanye nokuhlaziywa komkhiqizo wokugqwala. Izifundo ze-electrochemical ezifaka phakathi i-Open Circuit Potential (OCP), i-Linear Polarization Resistance (LPR), i-Electrochemical Impedance Spectroscopy (EIS), kanye ne-Potential Dynamic Polarization zenziwa ukuze kufundwe ukuziphatha kwe-MIC kwe-2707 HDSS. Ukuhlaziywa kwe-Energy dispersive spectrometer (EDS) kwenziwa ukuze kutholakale izakhi zamakhemikhali ebusweni obugqwalile. Ngaphezu kwalokho, ukuhlaziywa kwe-X-ray photoelectron spectroscopy (XPS) kwasetshenziswa ukunquma ukuzinza kwe-oxide film passivation ngaphansi kwethonya lendawo yasolwandle equkethe i-Pseudomonas aeruginosa. Ukujula komgodi kwalinganiswa ngaphansi kwe-confocal laser scanning microscope (CLSM).
Ithebula 1 libala ukwakheka kwamakhemikhali kwe-2707 HDSS. Ithebula 2 libonisa ukuthi i-2707 HDSS inezakhiwo ezinhle kakhulu zemishini ezinamandla okukhiqiza angu-650 MPa. Isithombe 1 sibonisa isakhiwo esincane se-optical sesisombululo esiphathwe ngokushisa esingu-2707 HDSS. Amabhendi amade ezigaba ze-austenite ne-ferrite ngaphandle kwezigaba zesibili angabonakala esakhiweni esincane esiqukethe cishe izigaba ze-austenite ezingu-50% kanye nezigaba ze-ferrite ezingu-50%.
Isibalo 2a sibonisa amandla okuvula i-open circuit (Eocp) uma kuqhathaniswa nedatha yesikhathi sokuchayeka se-2707 HDSS ku-abiotic 2216E medium kanye nomhluzi we-P. aeruginosa izinsuku eziyi-14 ku-37 °C. Sibonisa ukuthi ushintsho olukhulu nolubalulekile ku-Eocp lwenzeka emahoreni okuqala angama-24. Amanani e-Eocp kuzo zombili izimo afinyelele ku--145 mV (uma kuqhathaniswa ne-SCE) cishe emahoreni ayi-16 bese ehla kakhulu, afinyelela ku--477 mV (uma kuqhathaniswa ne-SCE) kanye no--236 mV (uma kuqhathaniswa ne-SCE) yesampula ye-abiotic kanye ne-P, ngokulandelana). Amakhuphoni e-Pseudomonas aeruginosa, ngokulandelana. Ngemva kwamahora angu-24, inani le-Eocp lika-2707 HDSS le-P. aeruginosa lalizinzile ku--228 mV (uma kuqhathaniswa ne-SCE), kuyilapho inani elihambisanayo lamasampula angewona awebhayoloji lalicishe libe ngu--442 mV (uma kuqhathaniswa ne-SCE). I-Eocp lapho kukhona i-P. aeruginosa yayiphansi impela.
Ukuhlolwa kwe-electrochemical kwamasampula e-HDSS angu-2707 ku-abiotic medium kanye nomhluzi we-Pseudomonas aeruginosa ku-37 °C:
(a) I-Eocp njengomsebenzi wesikhathi sokuchayeka, (b) amajika okuhlukaniswa kwe-polarization ngosuku lwe-14, (c) i-Rp njengomsebenzi wesikhathi sokuchayeka kanye (d) i-icorr njengomsebenzi wesikhathi sokuchayeka.
Ithebula 3 libala amanani epharamitha yokugqwala kwe-electrochemical yamasampula angu-2707 e-HDSS avezwe ku-abiotic medium kanye ne-Pseudomonas aeruginosa efakwe i-inculated medium izinsuku ezingu-14. Ama-tangent ama-anodic curve kanye ne-cathodic curves akhishwe ukuze afike ezimpambanweni eziveza ukuminyana kwamanje kokugqwala (icorr), amandla okugqwala (Ecorr) kanye ne-Tafel slopes (βα kanye ne-βc) ngokwezindlela ezijwayelekile30,31.
Njengoba kuboniswe kuMfanekiso 2b, ukushintsha okuphezulu kwejika le-P. aeruginosa kuholele ekwandeni kwe-Ecorr uma kuqhathaniswa nejika le-abiotic. Inani le-icorr, elilingana nesilinganiso sokugqwala, lenyuke laya ku-0.328 μA cm-2 kusampula ye-Pseudomonas aeruginosa, okuphindwe kane kunesampula engeyona eyebhayoloji (0.087 μA cm-2).
I-LPR iyindlela yakudala ye-electrochemical engabhubhisi yokuhlaziya ukugqwala okusheshayo. Yasetshenziswa futhi ukutadisha i-MIC32. Isithombe 2c sibonisa ukumelana kwe-polarization (Rp) njengomsebenzi wesikhathi sokuchayeka. Inani eliphakeme le-Rp lisho ukugqwala okuncane. Phakathi namahora okuqala angu-24, i-Rp ye-2707 HDSS ifinyelele inani eliphakeme lika-1955 kΩ cm2 kumasampula abiotic kanye no-1429 kΩ cm2 kumasampula e-Pseudomonas aeruginosa. Isithombe 2c sibonisa nokuthi inani le-Rp lehle ngokushesha ngemva kosuku olulodwa labe selihlala lingashintshi izinsuku ezingu-13 ezilandelayo. Inani le-Rp lesampula ye-Pseudomonas aeruginosa licishe libe ngu-40 kΩ cm2, eliphansi kakhulu kunenani elingu-450 kΩ cm2 lesampula engeyona eyebhayoloji.
Inani le-icorr lilingana nesilinganiso sokugqwala esifanayo. Inani lalo lingabalwa kusukela ku-equation elandelayo ye-Stern-Geary,
Ngemva kukaZou et al. 33, inani elijwayelekile le-Tafel slope B kulo msebenzi lalicatshangwa ukuthi lingu-26 mV/dec. Isithombe 2d sibonisa ukuthi i-icorr yesampula ye-2707 engeyona eyebhayoloji yahlala izinzile, kuyilapho isampula ye-P. aeruginosa ishintshashintsha kakhulu ngemva kwamahora okuqala angu-24. Amanani e-icorr amasampula e-P. aeruginosa ayephezulu kakhulu kunezilawuli ezingeyona eyebhayoloji. Lo mkhuba uhambisana nemiphumela yokumelana ne-polarization.
I-EIS ingenye indlela engeyona ebhubhisayo esetshenziselwa ukuchaza ukusabela kwe-electrochemical ezindaweni ezigqwalile. Ama-spectra e-Impedance kanye namanani e-capacitance abaliwe amasampula avezwe kwi-abiotic media kanye nesisombululo se-Pseudomonas aeruginosa, ukumelana kwe-Rb kwefilimu/i-biofilm engasebenzi eyakhiwe ebusweni besampula, ukumelana kokudluliselwa kweshaja ye-Rct, i-Cdl kagesi enezingqimba ezimbili ze-capacitance (EDL) kanye namapharamitha e-QCPE Constant Phase Element (CPE). Lawa mapharamitha ahlaziywa kabanzi ngokufaka idatha kusetshenziswa imodeli yesekethe elinganayo (EEC).
Isithombe 3 sibonisa ama-Nyquist plots ajwayelekile (a no-b) kanye nama-Bode plots (a' no-b') amasampula angu-2707 e-HDSS ku-abiotic medium kanye nomhluzi we-P. aeruginosa ngezikhathi ezahlukene zokufukamela. Ububanzi bendandatho ye-Nyquist buyancipha uma kukhona i-Pseudomonas aeruginosa. I-Bode plot (Umfanekiso 3b') ikhombisa ukwanda kobukhulu be-impedance iyonke. Ulwazi mayelana nesikhathi sokuphumula lunganikezwa yi-phase maxima. Isithombe 4 sibonisa izakhiwo zomzimba ezisekelwe ku-monolayer (a) kanye ne-bilayer (b) kanye nama-EEC azo ahambisanayo. I-CPE yethulwa kumodeli ye-EEC. Ukwamukelwa kwayo kanye ne-impedance kuvezwa kanje:
Amamodeli amabili angokwenyama kanye namasekethe alinganayo ahambisanayo okufaka i-spectrum ye-impedance yesampula ye-2707 HDSS:
lapho u-Y0 ubukhulu be-CPE, u-j uyinombolo ecatshangelwayo noma (-1)1/2, u-ω uyimvamisa ye-angular, kanti u-n uyinkomba yamandla e-CPE engaphansi kwe-unit35. I-inverse yokumelana nokudluliselwa kweshaja (okungukuthi i-1/Rct) ihambelana nesilinganiso sokugqwala. I-Rct encane isho izinga lokugqwala elisheshayo27. Ngemuva kwezinsuku ezingu-14 zokufukamela, i-Rct yamasampula e-Pseudomonas aeruginosa ifinyelele ku-32 kΩ cm2, encane kakhulu kune-489 kΩ cm2 yamasampula angewona awebhayoloji (Ithebula 4).
Izithombe ze-CLSM kanye nezithombe ze-SEM kuMfanekiso 5 zibonisa ngokusobala ukuthi ukumbozwa kwe-biofilm ebusweni besampula ye-2707 HDSS ngemuva kwezinsuku eziyi-7 kukhulu. Kodwa-ke, ngemva kwezinsuku eziyi-14, ukumbozwa kwe-biofilm kwakuncane futhi kwavela amanye amangqamuzana afile. Ithebula 5 libonisa ukujiya kwe-biofilm kumasampula e-2707 HDSS ngemuva kokuchayeka ku-P. aeruginosa izinsuku eziyi-7 neziyi-14. Ubukhulu obukhulu be-biofilm bushintshe kusuka ku-23.4 μm ngemva kwezinsuku eziyi-7 kuya ku-18.9 μm ngemva kwezinsuku eziyi-14. Ubukhulu obujwayelekile be-biofilm buqinisekisile lo mkhuba. Kwehle kusuka ku-22.2 ± 0.7 μm ngemva kwezinsuku eziyi-7 kuya ku-17.8 ± 1.0 μm ngemva kwezinsuku eziyi-14.
(a) Isithombe se-3-D CLSM ngemva kwezinsuku eziyi-7, (b) Isithombe se-3-D CLSM ngemva kwezinsuku eziyi-14, (c) Isithombe se-SEM ngemva kwezinsuku eziyi-7 kanye (d) Isithombe se-SEM ngemva kwezinsuku eziyi-14.
I-EDS yembule izakhi zamakhemikhali kuma-biofilms kanye nemikhiqizo yokugqwala kumasampula avezwe ku-P. aeruginosa izinsuku ezingu-14. Isithombe 6 sibonisa ukuthi okuqukethwe yi-C, N, O, kanye ne-P kuma-biofilms kanye nemikhiqizo yokugqwala kuphakeme kakhulu kunalokho okusezinsimbini ezingenalutho, ngoba lezi zakhi zihlotshaniswa nama-biofilms kanye nama-metabolites azo. Ama-microbes adinga kuphela inani elincane le-chromium kanye ne-iron. Amazinga aphezulu e-Cr kanye ne-Fe ku-biofilm kanye nemikhiqizo yokugqwala ebusweni bezibonelo abonisa ukuthi i-matrix yensimbi ilahlekelwe izakhi ngenxa yokugqwala.
Ngemva kwezinsuku ezingu-14, kwabonakala ukugoba okune-P. aeruginosa kanye nokungenayo ku-2216E medium. Ngaphambi kokugoba, ubuso besampula babubushelelezi futhi bungenasici (Isithombe 7a). Ngemva kokugoba kanye nokususwa kwemikhiqizo ye-biofilm kanye nokugqwala, imigodi ejulile ebusweni besampula yahlolwa ngaphansi kwe-CLSM, njengoba kuboniswe kuMfanekiso 7b kanye no-c. Azikho imigodi ecacile etholakale ebusweni besampula zokulawula ezingezona ezebhayoloji (ukujula komgodi okuphezulu okungu-0.02 μm). Ukujula komgodi okuphezulu okubangelwe yi-Pseudomonas aeruginosa kwakungu-0.52 μm ngemva kwezinsuku ezingu-7 kanye no-0.69 μm ngemva kwezinsuku ezingu-14, ngokusekelwe ekujuleni komgodi okuphezulu okumaphakathi kwamasampula angu-3 (amanani angu-10 okujula komgodi okuphezulu akhethiwe kusampula ngayinye) afinyelele ku-0.42 ± 0.12 μm kanye no-0.52 ± 0.15 μm, ngokulandelana (Ithebula 5). Lawa manani okujula komgodi mancane kodwa abalulekile.
(a) Ngaphambi kokuchayeka, (b) izinsuku ezingu-14 endaweni engenamagciwane kanye (c) izinsuku ezingu-14 kumhluzi we-Pseudomonas aeruginosa.
Isithombe 8 sibonisa ama-spectra e-XPS ezindawo ezahlukene zesampula, kanti ukwakheka kwamakhemikhali okuhlaziywe endaweni ngayinye kufingqiwe kuThebula 6. KuThebula 6, amaphesenti e-athomu e-Fe ne-Cr lapho kukhona i-P. aeruginosa (amasampula A no-B) ayephansi kakhulu kunalawo amasampula okulawula angewona awezinto eziphilayo (amasampula C no-D). Kwisampula ye-P. aeruginosa, ijika le-spectral level core level le-Cr 2p lafakwa ezingxenyeni ezine ze-peak ezinenani le-binding energy (BE) elingu-574.4, 576.6, 578.3 kanye no-586.8 eV, elingabalelwa ku-Cr, Cr2O3, CrO3 kanye ne-Cr(OH)3, ngokulandelana (Isithombe 9a kanye no-b). Kumasampula angewona awezinto eziphilayo, i-spectrum ye-core level ye-Cr 2p iqukethe iziqongo ezimbili eziyinhloko ze-Cr (573.80 eV ye-BE) kanye ne-Cr2O3 (575.90 eV ye-BE) kuThebula 9c kanye no-d, ngokulandelana. Okuhlaba umxhwele kakhulu Umehluko phakathi kwamasampula e-abiotic kanye ne-P. aeruginosa kwakuwukuba khona kwe-Cr6+ kanye nengxenye ephezulu ye-Cr(OH)3 (BE ka-586.8 eV) ngaphansi kwe-biofilm.
I-spectra ebanzi ye-XPS ebusweni besampula ye-2707 HDSS kulezi zindawo ezimbili ingamalanga ayi-7 kanye nezinsuku eziyi-14, ngokulandelana.
(a) Izinsuku eziyi-7 zokuchayeka ku-P. aeruginosa, (b) Izinsuku eziyi-14 zokuchayeka ku-P. aeruginosa, (c) Izinsuku eziyi-7 endaweni engasebenzi kanye (d) Izinsuku eziyi-14 endaweni engasebenzi.
I-HDSS ibonisa amazinga aphezulu okumelana nokugqwala ezindaweni eziningi. UKim nabanye 2 babike ukuthi i-UNS S32707 HDSS ichazwe njenge-DSS exutshwe kakhulu ene-PREN engaphezu kuka-45. Inani le-PREN lesampula ye-2707 HDSS kulo msebenzi lalingu-49. Lokhu kungenxa yokuqukethwe kwayo okuphezulu kwe-chromium kanye namazinga aphezulu e-molybdenum kanye ne-Ni, awusizo ezindaweni ezine-acidic kanye ne-chloride ephezulu. Ngaphezu kwalokho, ukwakheka okulinganiselayo kahle kanye nesakhiwo esincane esingenamaphutha kuyasiza ekuzinzeni kwesakhiwo kanye nokumelana nokugqwala. Kodwa-ke, naphezu kokumelana kwayo okuhle kwamakhemikhali, idatha yokuhlola kulo msebenzi iphakamisa ukuthi i-2707 HDSS ayivikelekile ngokuphelele kwi-MIC ye-P. aeruginosa biofilms.
Imiphumela ye-electrochemical ikhombisile ukuthi izinga lokugqwala kwe-2707 HDSS kumhluzi we-P. aeruginosa landa kakhulu ngemva kwezinsuku eziyi-14 uma kuqhathaniswa ne-non-biological medium. Ku-Figure 2a, ukwehla kwe-Eocp kwabonwa kokubili ku-abiotic medium kanye nomhluzi we-P. aeruginosa phakathi namahora okuqala angu-24. Ngemva kwalokho, i-biofilm isiqedile ukumboza ubuso besampula futhi i-Eocp iba yinto eqinile.36 Kodwa-ke, izinga le-biological Eocp laliphakeme kakhulu kunele-non-biological Eocp. Kunesizathu sokukholelwa ukuthi lo mehluko ubangelwa ukwakheka kwe-biofilm ye-P. aeruginosa. Ku-Fig. 2d, lapho kukhona i-P. aeruginosa, inani le-icorr le-2707 HDSS lafinyelela ku-0.627 μA cm-2, okwakuyi-oda lobukhulu obuphakeme kunelokulawula kwe-abiotic (0.063 μA cm-2), okwakuhambisana nenani le-Rct elilinganiswe yi-EIS. Phakathi nezinsuku ezimbalwa zokuqala, amanani e-impedance Kumhluzi we-P. aeruginosa kwanda ngenxa yokunamathela kwamaseli e-P. aeruginosa kanye nokwakheka kwama-biofilms. Kodwa-ke, lapho i-biofilm imboza ngokuphelele ubuso besampula, i-impedance iyancipha. Ingqimba yokuvikela ihlaselwa kuqala ngenxa yokwakheka kwama-biofilms kanye nama-metabolites e-biofilm. Ngakho-ke, ukumelana nokugqwala kwehla ngokuhamba kwesikhathi, futhi ukunamathela kwe-P. aeruginosa kubangele ukugqwala kwendawo. Izitayela zemidiya ye-abiotic zazihlukile. Ukumelana nokugqwala kokulawulwa okungeyona eyebhayoloji kwakuphakeme kakhulu kunenani elihambisanayo lamasampula adalulwe kumhluzi we-P. aeruginosa. Ngaphezu kwalokho, kumasampula e-abiotic, inani le-Rct le-2707 HDSS lifinyelele ku-489 kΩ cm2 ngosuku lwe-14, okwakuphindwe kayi-15 kunenani le-Rct (32 kΩ cm2) lapho kukhona i-P. aeruginosa. Ngakho-ke, i-2707 HDSS inokumelana okuhle kokugqwala endaweni engcolile, kodwa ayimelani nokuhlaselwa yi-MIC yi-P. aeruginosa biofilms.
Le miphumela ingabonakala futhi kusukela kuma-polarization curves ku-Fig. 2b. Ukusabalala kwe-anodic kuhlotshaniswa nokwakheka kwe-biofilm ye-Pseudomonas aeruginosa kanye nokusabela kwe-oxidation yensimbi. Ngesikhathi esifanayo ukusabela kwe-cathodic kungukuncipha komoya-mpilo. Ukuba khona kwe-P. aeruginosa kwandisa kakhulu ubuningi bamanje okugqwala, cishe ngomyalelo wobukhulu obuphakeme kunokulawulwa kwe-abiotic. Lokhu kubonisa ukuthi i-P. aeruginosa biofilm ikhulisa ukugqwala kwendawo kwe-2707 HDSS. UYuan et al29 bathole ukuthi ubuningi bamanje okugqwala kwe-70/30 Cu-Ni alloy bukhuphuke ngaphansi kwenselelo ye-P. aeruginosa biofilm. Lokhu kungase kube ngenxa ye-biocatalysis yokunciphisa umoya-mpilo yi-Pseudomonas aeruginosa biofilms. Lokhu kuqaphela kungachaza ne-MIC ye-2707 HDSS kulo msebenzi. Ama-biofilm e-aerobic nawo angase abe nomoya-mpilo omncane ngaphansi kwawo. Ngakho-ke, ukwehluleka ukuphinda kudlule ubuso bensimbi nge-oxygen kungaba yisici esifaka isandla kwi-MIC kulo msebenzi.
UDickinson nabanye 38 basikisele ukuthi amazinga okusabela kwamakhemikhali kanye ne-electrochemical angathinteka ngqo ngumsebenzi we-metabolic wamabhaktheriya e-sessile ebusweni besampula kanye nohlobo lwemikhiqizo yokugqwala. Njengoba kuboniswe kuMfanekiso 5 kanye neThebula 5, kokubili inombolo yamaseli kanye nobukhulu be-biofilm kwehle ngemva kwezinsuku ezingu-14. Lokhu kungachazwa ngokunengqondo ukuthi ngemva kwezinsuku ezingu-14, iningi lamaseli e-sessile ebusweni be-2707 HDSS lafa ngenxa yokuncipha kwezakhamzimba endaweni ye-2216E noma ukukhishwa kwama-ion ensimbi anobuthi avela ku-2707 HDSS matrix. Lokhu kungumkhawulo wokuhlolwa kwe-batch.
Kulo msebenzi, i-biofilm ye-P. aeruginosa ikhuthaze ukuncipha kwendawo kwe-Cr ne-Fe ngaphansi kwe-biofilm ebusweni be-2707 HDSS (Isithombe 6). KuThebula 6, ukwehla kwe-Fe ne-Cr kusampula D uma kuqhathaniswa nesampula C, okubonisa ukuthi i-Fe ne-Cr encibilikisiwe ebangelwe yi-biofilm ye-P. aeruginosa yaqhubeka ngale kwezinsuku eziyi-7 zokuqala. I-medium ye-2216E isetshenziselwa ukulingisa izindawo zasolwandle. Iqukethe i-17700 ppm Cl-, efana naleyo etholakala emanzini olwandle emvelo. Ukuba khona kwe-17700 ppm Cl- kwakuyisizathu esiyinhloko sokuncipha kwe-Cr kumasampula e-abiotic ezinsuku eziyi-7 nezinsuku eziyi-14 ahlaziywe yi-XPS. Uma kuqhathaniswa namasampula e-P. aeruginosa, ukuchithwa kwe-Cr kumasampula e-abiotic kwakuncane kakhulu ngenxa yokumelana okunamandla kwe-Cl− kwe-2707 HDSS ezindaweni ze-abiotic.Isithombe 9 sibonisa ukuba khona kwe-Cr6+ kufilimu ye-passivation.Kungase kuhileleke ekususweni kwe-Cr ezindaweni zensimbi yi-P. aeruginosa biofilms, njengoba kuphakanyiswe nguChen noClayton.
Ngenxa yokukhula kwamagciwane, amanani e-pH ye-medium ngaphambi nangemva kokutshala ayengu-7.4 no-8.2, ngokulandelana. Ngakho-ke, ngaphansi kwe-biofilm ye-P. aeruginosa, ukugqwala kwe-organic acid akunakwenzeka ukuthi kube yimbangela yalo msebenzi ngenxa ye-pH ephezulu kakhulu ku-bulk medium. I-pH ye-non-biological control medium ayizange ishintshe kakhulu (kusukela ku-7.4 yokuqala kuya ku-7.5 yokugcina) phakathi nesikhathi sokuhlolwa sezinsuku ezingu-14. Ukwanda kwe-pH ku-inculation medium ngemva kokufukamela kwakungenxa yomsebenzi we-metabolic we-P. aeruginosa futhi kwatholakala ukuthi kunomphumela ofanayo ku-pH lapho kungekho khona imichilo yokuhlola.
Njengoba kuboniswe kuMfanekiso 7, ukujula komgodi okuphezulu okubangelwe yi-P. aeruginosa biofilm kwakungu-0.69 μm, okwakukhulu kakhulu kunokwe-abiotic medium (0.02 μm). Lokhu kuhambisana nedatha ye-electrochemical echazwe ngenhla. Ukujula komgodi ongu-0.69 μm kuncane ngokuphindwe kayishumi kunenani elingu-9.5 μm elibikwe ku-2205 DSS ngaphansi kwezimo ezifanayo. Le datha ikhombisa ukuthi i-2707 HDSS ikhombisa ukumelana okungcono kwe-MIC uma kuqhathaniswa ne-2205 DSS. Lokhu akufanele kumangaze, njengoba i-2707 HDSS inokuqukethwe okuphezulu kwe-chromium, okunikeza ukudlula okuhlala isikhathi eside, ngenxa yesakhiwo sesigaba esilinganiselwe ngaphandle kwe-precipitates yesibili eyingozi, okwenza kube nzima nge-P. aeruginosa ukukhipha ukudlula kanye nokuqala amaphuzu e-eclipse.
Ekuphetheni, i-MIC pitting itholakale ebusweni be-2707 HDSS kumhluzi we-P. aeruginosa uma kuqhathaniswa ne-pitting encane kakhulu kwimidiya ye-abiotic. Lo msebenzi ukhombisa ukuthi i-2707 HDSS inokumelana okungcono kwe-MIC kune-2205 DSS, kodwa ayivikelekile ngokuphelele kwi-MIC ngenxa ye-P. aeruginosa biofilm. Lokhu okutholakele kusiza ekukhetheni izinsimbi ezingagqwali ezifanele kanye nokuphila okulinganiselwe kwenkonzo yemvelo yasolwandle.
Ikhuphoni le-2707 HDSS linikezwa yiSikole Sensimbi saseNortheastern University (NEU) eShenyang, eShayina. Ukwakheka kwezakhi ze-2707 HDSS kuboniswe kuThebula 1, elahlaziywa yi-NEU Materials Analysis and Testing Department. Wonke amasampula aphathwa ngesisombululo ku-1180 °C ihora eli-1. Ngaphambi kokuhlolwa kokugqwala, i-2707 HDSS emise okwenhlamvu enesikhala esiphezulu esivezwe phezulu esingu-1 cm2 yapholishwa yaba yi-grit engu-2000 ngephepha le-silicon carbide futhi yapholishwa nge-powder suspension engu-0.05 μm Al2O3 engu-0.05 μm. Izinhlangothi kanye nephansi zivikelwe ngopende ongagqwali. Ngemva kokomiswa, amasampula ahlanzwa ngamanzi angcolile acwebezelwe futhi ahlanzwa nge-ethanol engu-75% (v/v) amahora angu-0.5. Abe esemiswa emoyeni ngaphansi kokukhanya kwe-ultraviolet (UV) amahora angu-0.5 ngaphambi kokusetshenziswa.
Uhlobo lweMarine Pseudomonas aeruginosa MCCC 1A00099 lwathengwa eXiamen Marine Culture Collection Center (MCCC), eShayina. I-Pseudomonas aeruginosa yakhuliswa ngokulinganisela amazinga okushisa ku-37°C kumaflaski angu-250 ml kanye namaseli engilazi kagesi angu-500 ml kusetshenziswa i-Marine 2216E liquid medium (Qingdao Hope Biotechnology Co., Ltd., eQingdao, eShayina). Okuphakathi (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 kanye ne-0.1 ferric citrate. I-Autoclave ku-121°C imizuzu engama-20 ngaphambi kokugoma. Bala amaseli e-sessile kanye ne-planktonic usebenzisa i-hemocytometer ngaphansi kwe-microscope ekhanyayo ku-400X magnification. Ukuhlushwa kwamaseli okuqala e-planktonic Pseudomonas aeruginosa ngokushesha ngemva kokugoma kwakungaba amaseli ayi-106/ml.
Ukuhlolwa kwe-electrochemical kwenziwe esitokisini sengilazi esidala sama-electrode amathathu esinomthamo ophakathi ongu-500 ml. Ishidi leplatinum kanye ne-electrode ye-calomel egcwele (SCE) kuxhunywe ku-reactor ngama-capillary e-Luggin agcwele amabhuloho kasawoti, asebenza njengama-electrode aphikisayo kanye nereferensi, ngokulandelana. Ukuze kwenziwe ama-electrode asebenzayo, ucingo lwethusi olumbozwe ngerabha lunamathiselwe kusampula ngayinye futhi lumbozwe nge-epoxy, kwasala cishe u-1 cm2 wendawo evulekile yohlangothi olulodwa ye-electrode esebenzayo. Ngesikhathi sokulinganisa kwe-electrochemical, amasampula afakwa ku-2216E medium futhi agcinwa ekushiseni okuhlala njalo kwe-incubation (37 °C) ebhavini lamanzi. Idatha ye-OCP, i-LPR, i-EIS kanye nedatha ye-polarization enamandla engaba khona ilinganiswe kusetshenziswa i-Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA). Ukuhlolwa kwe-LPR kuqoshwe ngesilinganiso sokuskena esingu-0.125 mV s-1 ebangeni eliphakathi kuka--5 no-5 mV ne-Eocp kanye nemvamisa yokusampula engu-1 Hz. I-EIS yenziwe nge-sine wave ebangeni lemvamisa. 0.01 kuya ku-10,000 Hz kusetshenziswa i-voltage esetshenziswayo engu-5 mV ku-Eocp ezinzile. Ngaphambi kokushanela okungenzeka, ama-electrode ayekwimodi ye-open-circuit kuze kube yilapho kufinyelelwa inani elizinzile lokugqwala okungaguquki. Ama-curve e-Polarization abe esesebenza kusukela ku--0.2 kuya ku-1.5 V vs. Eocp ngesilinganiso sokuskena esingu-0.166 mV/s. Ukuhlolwa ngakunye kwaphindwa izikhathi ezi-3 nge-P. aeruginosa nangaphandle kwayo.
Amasampula okuhlaziywa kwe-metallographic apholishwe ngomshini ngephepha le-SiC elimanzi elingu-2000 grit bese epholishwa ngokwengeziwe nge-0.05 μm Al2O3 powder suspension ukuze kubonwe ngamehlo. Ukuhlaziywa kwe-metallographic kwenziwa kusetshenziswa i-optical microscope. Amasampula aqoshwe ngesisombululo se-potassium hydroxide esingu-10 wt.% 43.
Ngemva kokufuthwa, amasampula ahlanzwa izikhathi ezintathu ngesisombululo se-phosphate-buffered saline (PBS) (pH 7.4 ± 0.2) bese elungiswa nge-2.5% (v/v) glutaraldehyde amahora ayi-10 ukuze kulungiswe ama-biofilms. Ngemuva kwalokho akhishwa amanzi ngochungechunge olulinganisiwe (50%, 60%, 70%, 80%, 90%, 95% kanye no-100% v/v) lwe-ethanol ngaphambi kokumiswa emoyeni. Okokugcina, ubuso besampula bugcotshwa ngefilimu yegolide ukuze kuhlinzekwe ngogesi wokubona i-SEM. Izithombe ze-SEM zigxile ezindaweni ezinamaseli e-P. aeruginosa athambile kakhulu ebusweni besampula ngayinye. Yenza ukuhlaziywa kwe-EDS ukuthola izakhi zamakhemikhali. I-Zeiss Confocal Laser Scanning Microscope (CLSM) (LSM 710, Zeiss, Germany) yasetshenziswa ukukala ukujula komgodi. Ukuze kubonwe imigodi yokugqwala ngaphansi kwe-biofilm, ingxenye yokuhlola yahlanzwa kuqala ngokusho kwe- I-Chinese National Standard (CNS) GB/T4334.4-2000 ukususa imikhiqizo yokugqwala kanye ne-biofilm ebusweni bengxenye yokuhlola.
Ukuhlaziywa kwe-X-ray photoelectron spectroscopy (i-XPS, uhlelo lokuhlaziya ubuso lwe-ESCALAB250, i-Thermo VG, e-USA) kwenziwe kusetshenziswa umthombo we-X-ray we-monochromatic (umugqa we-aluminium Kα kumandla angu-1500 eV kanye namandla angu-150 W) phezu kwebanga elibanzi lamandla okubopha angu-0 ngaphansi kwezimo ezijwayelekile -1350 eV. Ama-spectra anesinqumo esiphezulu aqoshwe kusetshenziswa amandla okudlula angu-50 eV kanye nosayizi wesinyathelo esingu-0.2 eV.
Amasampula afakwe esikhumbeni asusiwe futhi ahlanzwa ngobumnene nge-PBS (pH 7.4 ± 0.2) imizuzu engu-15 s45. Ukuze kubonwe ukuthi ama-biofilms aphila kahle yini kumasampula, ama-biofilms afakwe esikhumbeni kusetshenziswa i-LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, USA). Le khithi inamadayi amabili e-fluorescent, idayi eluhlaza okwesibhakabhaka ye-SYTO-9 kanye nedayi ebomvu ye-fluorescent propidium iodide (PI). Ngaphansi kwe-CLSM, amachashazi anombala oluhlaza okwesibhakabhaka kanye nobomvu amelela amaseli aphilayo nafile, ngokulandelana. Ukuze kufakwe esikhumbeni, ingxube engu-1 ml equkethe isisombululo se-3 μl SYTO-9 kanye nesisombululo se-3 μl PI yafakwa esikhumbeni imizuzu engama-20 ekushiseni kwegumbi (23 oC) ebumnyameni. Ngemva kwalokho, amasampula afakwe esikhumbeni abonwa ngama-wavelength amabili (488 nm kumaseli aphilayo kanye no-559 nm kumaseli afile) kusetshenziswa umshini we-Nikon CLSM (C2 Plus, Nikon, Japan). Ubukhulu be-Biofilm bulinganiswe ku Imodi yokuskena ye-3-D.
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