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Tsatsa ta ƙwayoyin cuta (MIC) babbar matsala ce a masana'antu da yawa, domin tana iya haifar da asarar tattalin arziki mai yawa. Ana amfani da ƙarfe mai ƙarfi mai ƙarfi 2707 (2707 HDSS) a cikin yanayin ruwa saboda kyakkyawan juriyarsa ga sinadarai. Duk da haka, ba a nuna juriyarsa ga MIC ta hanyar gwaji ba. Wannan binciken ya binciki halayen MIC 2707 HDSS wanda kwayar halittar iskar gas ta ruwa Pseudomonas aeruginosa ke haifarwa. Binciken lantarki ya nuna cewa a gaban biofilm na Pseudomonas aeruginosa a cikin matsakaiciyar 2216E, canji mai kyau a cikin yuwuwar tsatsa da ƙaruwa a yawan tsatsa. Binciken X-ray photoelectron spectroscopy (XPS) ya nuna raguwar abun ciki na Cr akan saman samfurin a ƙarƙashin biofilm ɗin. Binciken gani na ramukan ya nuna cewa biofilm na P. aeruginosa ya samar da zurfin rami na 0.69 µm a cikin kwanaki 14 na ƙullawa. Duk da cewa wannan ƙarami ne, yana nuna cewa 2707 HDSS ba shi da cikakken kariya daga MIC na biofilms na P. aeruginosa.
Ana amfani da ƙarfe mai kauri (DSS) sosai a masana'antu daban-daban saboda cikakkiyar haɗuwa ta kyawawan halayen injiniya da juriya ga tsatsa1,2. Duk da haka, ramin da aka gina a cikin gida har yanzu yana faruwa kuma yana shafar amincin wannan ƙarfe3,4. DSS ba ta da juriya ga tsatsa mai ƙwayoyin cuta (MIC)5,6. Duk da yawan aikace-aikacen DSS, har yanzu akwai wurare inda juriyar tsatsa ta DSS ba ta isa ba don amfani na dogon lokaci. Wannan yana nufin cewa ana buƙatar kayan da suka fi tsada waɗanda ke da juriya ga tsatsa. Jeon et al7 sun gano cewa ko da ƙarfe mai kauri (SDSS) suna da wasu ƙuntatawa dangane da juriya ga tsatsa. Saboda haka, a wasu lokuta, ana buƙatar ƙarfe mai kauri (HDSS) tare da juriya ga tsatsa. Wannan ya haifar da haɓaka HDSS mai kauri.
DSS juriyar tsatsa ta dogara ne akan rabon matakan alpha da gamma kuma ta ragu a yankunan Cr, Mo da W 8, 9, 10 kusa da mataki na biyu. HDSS ya ƙunshi babban abun ciki na Cr, Mo da N11, saboda haka yana da kyakkyawan juriyar tsatsa da kuma babban ƙima (45-50) na daidai adadin juriyar pitting (PREN) wanda aka ƙaddara ta wt.% Cr + 3.3 (wt.% Mo + 0.5 wt. .%W) + 16% wt. N12. Kyakkyawan juriyar tsatsa ya dogara ne akan daidaitaccen abun da ke ɗauke da kusan 50% ferritic (α) da 50% austenitic (γ). HDSS yana da kyawawan halaye na injiniya da kuma juriya mafi girma ga tsatsa chloride. Ingantaccen juriyar tsatsa yana ƙara amfani da HDSS a cikin yanayin chloride mai ƙarfi kamar yanayin ruwa.
MICs babbar matsala ce a masana'antu da yawa kamar masana'antar mai da iskar gas da ruwa14. MIC tana da kashi 20% na duk lalacewar tsatsa15. MIC tsatsa ce ta bioelectrochemical wacce za a iya gani a wurare da yawa. Biofilms da ke samuwa a saman ƙarfe suna canza yanayin electrochemical, wanda hakan ke shafar tsarin tsatsa. Ana kyautata zaton cewa tsatsa ta MIC tana faruwa ne ta hanyar biofilms. Kwayoyin halittar lantarki suna cinye karafa don samun kuzarin da suke buƙata don rayuwa17. Binciken MIC na baya-bayan nan ya nuna cewa EET (canja wurin electron na waje) shine abin da ke iyakance saurin MIC wanda ƙwayoyin halittar lantarki ke haifarwa. Zhang et al. 18 sun nuna cewa masu shiga tsakani na electrons suna hanzarta canja wurin electrons tsakanin ƙwayoyin Desulfovibrio sessificans da ƙarfe 304 na bakin ƙarfe, wanda ke haifar da mummunan harin MIC. Anning et al. 19 da Wenzlaff et al. 20 sun nuna cewa biofilms na ƙwayoyin cuta masu rage sulfate (SRBs) na iya sha electrons kai tsaye daga ƙarfe, wanda ke haifar da mummunan rami.
An san DSS tana da saurin kamuwa da MIC a cikin kafofin watsa labarai da ke ɗauke da SRBs, ƙwayoyin cuta masu rage ƙarfe (IRBs), da sauransu. 21. Waɗannan ƙwayoyin cuta suna haifar da ramuka a saman DSS a ƙarƙashin biofilms22,23. Ba kamar DSS ba, ba a san HDSS24 MIC sosai ba.
Pseudomonas aeruginosa kwayar cuta ce mai kama da Gram-negative, mai motsi, mai siffar sanda wadda take yaɗuwa sosai a yanayi25. Pseudomonas aeruginosa kuma babban rukuni ne na ƙwayoyin cuta a cikin yanayin ruwa, wanda ke haifar da ƙaruwar yawan MIC. Pseudomonas yana da hannu sosai a cikin tsarin tsatsa kuma an san shi a matsayin majagaba a cikin mamaya yayin ƙirƙirar biofilm. Mahat et al. 28 da Yuan et al. 29 sun nuna cewa Pseudomonas aeruginosa yana ƙara yawan tsatsa na ƙarfe mai laushi da ƙarfe a cikin yanayin ruwa.
Babban manufar wannan aikin shine a binciki halayen MIC 2707 HDSS wanda kwayar halittar iskar oxygen ta ruwa Pseudomonas aeruginosa ke haifarwa ta amfani da hanyoyin lantarki, hanyoyin nazarin saman da kuma nazarin samfurin lalata. An gudanar da nazarin lantarki, gami da damar da'ira ta bude (OCP), juriya ta layin polarization (LPR), electrochemical impedance spectroscopy (EIS), da kuma yiwuwar polarization mai karfi, don nazarin halayen MIC 2707 HDSS. An gudanar da nazarin makamashi mai rarrabawa (EDS) don gano abubuwan sinadarai a saman da ya lalace. Bugu da ƙari, an yi amfani da X-ray photoelectron spectroscopy (XPS) don tantance daidaiton passivation na fim ɗin oxide a ƙarƙashin tasirin yanayin ruwa wanda ke ɗauke da Pseudomonas aeruginosa. An auna zurfin ramukan a ƙarƙashin na'urar daukar hoton laser confocal (CLSM).
Tebur na 1 yana nuna sinadaran da ke cikin 2707 HDSS. Tebur na 2 ya nuna cewa 2707 HDSS yana da kyawawan kaddarorin injiniya tare da ƙarfin yawan amfanin ƙasa na 650 MPa. A hoto na 1 yana nuna tsarin gani na maganin zafi da aka yi wa magani da zafi na 2707 HDSS. A cikin tsarin da ke ɗauke da kusan kashi 50% na austenite da kashi 50% na ferrite, ana iya ganin madaurin austenite da ferrite masu tsayi ba tare da matakai na biyu ba.
A hoto na 2a, yana nuna yiwuwar buɗewar da'ira (Eocp) idan aka kwatanta da lokacin fallasa na 2707 HDSS a cikin matsakaici na abiotic na 2216E da ruwan P. aeruginosa na tsawon kwanaki 14 a zafin jiki na 37°C. Yana nuna cewa mafi girma kuma mafi mahimmanci canji a cikin Eocp yana faruwa a cikin awanni 24 na farko. Ƙimar Eocp a duka lamuran biyu sun kai kololuwa a -145 mV (idan aka kwatanta da SCE) kimanin awanni 16 sannan suka faɗi da ƙarfi, suka kai -477 mV (idan aka kwatanta da SCE) da -236 mV (idan aka kwatanta da SCE) don samfurin abiotic. da kuma takardun P Pseudomonas aeruginosa, bi da bi). Bayan awanni 24, ƙimar Eocp 2707 HDSS don P. aeruginosa ta kasance mai daidaito a -228 mV (idan aka kwatanta da SCE), yayin da ƙimar da ta dace don samfuran da ba na halitta ba ta kasance kusan -442 mV (idan aka kwatanta da SCE). Eocp a gaban P. aeruginosa ya yi ƙasa sosai.
Nazarin lantarki na samfuran HDSS 2707 a cikin ruwan 'ya'yan itace mai hana ƙwayoyin cuta da ruwan 'ya'yan itace mai hana ƙwayoyin cuta na Pseudomonas aeruginosa a zafin digiri 37 na Celsius:
(a) Eocp a matsayin aikin lokacin fallasa, (b) lanƙwasa polarization a rana ta 14, (c) Rp a matsayin aikin lokacin fallasa, da kuma (d) icorr a matsayin aikin lokacin fallasa.
Tebur na 3 yana nuna sigogin tsatsa na lantarki na samfuran HDSS 2707 da aka fallasa ga abiotic da Pseudomonas aeruginosa da aka yi wa allurar rigakafi na tsawon kwanaki 14. An cire tangent na lanƙwasa na anode da cathode don samun mahadar da ke ba da yawan tsatsa (icorr), yuwuwar tsatsa (Ecorr) da gangaren Tafel (βα da βc) bisa ga hanyoyin da aka saba amfani da su30,31.
Kamar yadda aka nuna a cikin hoto na 2b, canjin sama a cikin lanƙwasa P. aeruginosa ya haifar da ƙaruwa a cikin Ecorr idan aka kwatanta da lanƙwasa abiotic. Ƙimar icorr, wacce take daidai da ƙimar tsatsa, ta ƙaru zuwa 0.328 µA cm-2 a cikin samfurin Pseudomonas aeruginosa, wanda ya ninka sau huɗu fiye da na samfurin da ba na halitta ba (0.087 µA cm-2).
LPR wata hanya ce ta lantarki wadda ba ta lalata ba don nazarin lalata cikin sauri. An kuma yi amfani da ita don nazarin MIC32. A hoto na 2c yana nuna juriyar polarization (Rp) a matsayin aikin lokacin fallasa. Babban ƙimar Rp yana nufin ƙarancin tsatsa. A cikin awanni 24 na farko, Rp 2707 HDSS ya kai kololuwar 1955 kΩ cm2 don samfuran abiotic da 1429 kΩ cm2 don samfuran Pseudomonas aeruginosa. Hoto na 2c kuma ya nuna cewa ƙimar Rp ta ragu da sauri bayan kwana ɗaya sannan ta kasance ba ta canzawa ba a cikin kwanaki 13 masu zuwa. Ƙimar Rp na samfurin Pseudomonas aeruginosa kusan 40 kΩ cm2 ne, wanda ya yi ƙasa da ƙimar 450 kΩ cm2 na samfurin da ba na halitta ba.
Darajar icorr tana daidai da ƙimar tsatsa iri ɗaya. Ana iya ƙididdige ƙimar ta daga lissafin Stern-Giri mai zuwa:
A cewar Zoe et al. 33, an ɗauki ƙimar da aka saba gani ta gangaren Tafel B a cikin wannan aikin zuwa 26 mV/dec. Hoto na 2d ya nuna cewa alamar samfurin da ba na halitta ba 2707 ta kasance mai daidaito, yayin da samfurin P. aeruginosa ya canza sosai bayan awanni 24 na farko. Ƙimar icorr na samfuran P. aeruginosa sun kasance mafi girma fiye da na sarrafawa marasa ilimin halitta. Wannan yanayin ya yi daidai da sakamakon juriyar polarization.
EIS wata hanya ce da ba ta lalatawa da ake amfani da ita don kwatanta halayen lantarki a saman da suka lalace. Spectra na impedance da ƙimar capacitance da aka ƙididdige na samfuran da aka fallasa ga yanayin abiotic da maganin Pseudomonas aeruginosa, juriyar fim/biofilm Rb da aka samar akan saman samfurin, juriyar canja wurin caji Rct, ƙarfin lantarki mai layi biyu na Cdl (EDL) da sigogin abubuwan da ke cikin lokaci na QCPE (CPE). An ƙara yin nazarin waɗannan sigogi ta hanyar haɗa bayanai ta amfani da samfurin da'ira daidai (EEC).
A kan hoto na 3 yana nuna taswirar Nyquist (a da b) da taswirar Bode (a' da b') na samfuran HDSS 2707 a cikin kafofin watsa labarai na abiotic da ruwan P. aeruginosa don lokutan haɗuwa daban-daban. Diamita na zoben Nyquist yana raguwa a gaban Pseudomonas aeruginosa. Tsarin Bode (Hoto na 3b') yana nuna ƙaruwar jimlar impedance. Ana iya samun bayanai game da ma'aunin lokacin shakatawa daga matakin maxima. A kan hoto na 4 yana nuna tsarin zahiri bisa ga monolayer (a) da bilayer (b) da EECs masu dacewa. An gabatar da CPE cikin samfurin EEC. An bayyana shigarsa da impedance kamar haka:
Samfura biyu na zahiri da da'irori masu dacewa don dacewa da bakan impedance na samfurin 2707 HDSS:
inda Y0 shine ƙimar KPI, j shine lambar da aka yi tunanin ko (-1) 1/2, ω shine mitar kusurwa, n shine ma'aunin ƙarfin KPI ƙasa da ɗaya35. Juyawar juriyar canja wurin caji (watau 1/Rct) yayi daidai da ƙimar tsatsa. Ƙaramin Rct, mafi girman ƙimar tsatsa27. Bayan kwanaki 14 na haɗuwa, samfuran Rct na Pseudomonas aeruginosa sun kai 32 kΩ cm2, wanda ya yi ƙasa da 489 kΩ cm2 na samfuran da ba na halitta ba (Tebur 4).
Hotunan CLSM da hotunan SEM a cikin Hoto na 5 sun nuna a sarari cewa murfin biofilm ɗin da ke saman samfurin HDSS 2707 bayan kwana 7 yana da yawa. Duk da haka, bayan kwana 14, murfin biofilm ɗin bai yi kyau ba kuma wasu ƙwayoyin halitta matattun sun bayyana. Tebur na 5 yana nuna kauri na biofilm akan samfuran HDSS 2707 bayan fallasa su ga P. aeruginosa na tsawon kwanaki 7 da 14. Matsakaicin kauri na biofilm ya canza daga 23.4 µm bayan kwana 7 zuwa 18.9 µm bayan kwana 14. Matsakaicin kauri na biofilm shi ma ya tabbatar da wannan yanayin. Ya ragu daga 22.2 ± 0.7 μm bayan kwana 7 zuwa 17.8 ± 1.0 μm bayan kwana 14.
(a) Hoton CLSM mai 3-D a kwana 7, (b) Hoton CLSM mai 3-D a kwana 14, (c) Hoton SEM a kwana 7, da kuma (d) Hoton SEM a kwana 14.
EMF ta bayyana sinadaran da ke cikin biofilms da kayayyakin tsatsa a kan samfuran da aka fallasa ga P. aeruginosa na tsawon kwanaki 14. A hoto na 6 ya nuna cewa abubuwan da ke cikin C, N, O, da P a cikin biofilms da kayayyakin tsatsa sun fi yawa fiye da na ƙarfe tsarkakakku, tunda waɗannan abubuwan suna da alaƙa da biofilms da metabolites ɗinsu. Ƙananan ƙwayoyin cuta suna buƙatar ƙaramin adadin chromium da baƙin ƙarfe kawai. Babban matakan Cr da Fe a cikin biofilm da samfuran tsatsa a saman samfuran sun nuna cewa matrix ɗin ƙarfe ya rasa abubuwa saboda tsatsa.
Bayan kwana 14, an lura da ramuka tare da kuma ba tare da P. aeruginosa ba a matsakaicin 2216E. Kafin a rufe saman samfuran, saman samfuran ya kasance mai santsi kuma babu lahani (Hoto na 7a). Bayan an rufe da kuma cire samfuran biofilm da tsatsa, an duba mafi zurfin ramuka a saman samfuran ta amfani da CLSM, kamar yadda aka nuna a Hoto na 7b da c. Ba a sami rami a bayyane a saman abubuwan da ba na halitta ba (zurfin rami mafi girma 0.02 µm). Matsakaicin zurfin ramin da P. aeruginosa ya haifar shine 0.52 µm a cikin kwanaki 7 da 0.69 µm a cikin kwanaki 14, bisa ga matsakaicin matsakaicin zurfin rami daga samfura 3 (an zaɓi mafi girman zurfin rami 10 ga kowane samfurin). Nasarar 0.42 ± 0.12 µm da 0.52 ± 0.15 µm, bi da bi (Tebur 5). Waɗannan ƙimar zurfin ramin suna da ƙanana amma suna da mahimmanci.
(a) kafin a fallasa shi, (b) kwana 14 a cikin yanayin da ba shi da kariya daga cututtuka, da kuma (c) kwana 14 a cikin ruwan Pseudomonas aeruginosa.
A kan siffa ta 8, Tebur ta nuna nau'in XPS na saman samfura daban-daban, kuma an taƙaita abubuwan da aka yi nazari a kansu na kowane saman a cikin Tebur ta 6. A cikin Tebur ta 6, kashi-kashi na atomic na Fe da Cr a gaban P. aeruginosa (samfura A da B) sun yi ƙasa da na waɗanda ba na halittu ba. (samfura C da D). Ga samfurin P. aeruginosa, an sanya lanƙwasa na spectral a matakin Cr 2p nucleus zuwa ga sassan kololuwa huɗu tare da kuzarin ɗaurewa (BE) na 574.4, 576.6, 578.3 da 586.8 eV, wanda za a iya dangantawa da Cr, Cr2O3, CrO3. da Cr(OH)3, bi da bi (Hoto na 9a da b). Ga samfuran da ba na halitta ba, bakan babban matakin Cr 2p ya ƙunshi manyan kololuwa guda biyu na Cr (573.80 eV don BE) da Cr2O3 (575.90 eV don BE) a cikin Fig. 9c da d, bi da bi. Bambanci mafi ban mamaki tsakanin samfuran abiotic da samfuran P. aeruginosa shine kasancewar Cr6+ da mafi girman rabo na Cr(OH)3 (BE 586.8 eV) a ƙarƙashin biofilm.
Faɗin XPS na saman samfurin 2707 HDSS a cikin kafofin watsa labarai guda biyu shine kwanaki 7 da 14, bi da bi.
(a) Kwanaki 7 na fallasa ga P. aeruginosa, (b) Kwanaki 14 na fallasa ga P. aeruginosa, (c) Kwanaki 7 a cikin yanayin rashin lafiyar jiki, da kuma (d) Kwanaki 14 a cikin yanayin rashin lafiyar jiki.
HDSS yana nuna babban matakin juriya ga tsatsa a mafi yawan muhalli. Kim et al.2 sun ruwaito cewa an gano HDSS UNS S32707 a matsayin DSS mai haɗakar sinadarai mai yawa tare da PREN fiye da 45. Darajar PREN na samfurin 2707 HDSS a cikin wannan aikin shine 49. Wannan ya faru ne saboda yawan sinadarin chromium da kuma yawan sinadarin molybdenum da nickel, waɗanda ke da amfani a cikin muhallin acidic. da muhallin da ke da yawan sinadarin chloride. Bugu da ƙari, tsarin da ya dace da daidaito da kuma tsarin da ba shi da lahani yana da amfani ga kwanciyar hankali na tsari da juriya ga tsatsa. Duk da haka, duk da kyakkyawan juriyarsa ga sinadarai, bayanan gwaji a cikin wannan aikin sun nuna cewa 2707 HDSS ba shi da cikakken kariya daga P. aeruginosa biofilm MICs.
Sakamakon lantarki ya nuna cewa yawan tsatsa na 2707 HDSS a cikin ruwan P. aeruginosa ya ƙaru sosai bayan kwana 14 idan aka kwatanta da yanayin da ba na halitta ba. A cikin Hoto na 2a, an lura da raguwar Eocp a cikin yanayin abiotic da kuma ruwan P. aeruginosa a cikin awanni 24 na farko. Bayan haka, biofilm ɗin ya rufe saman samfurin gaba ɗaya, kuma Eocp ya zama mai karko36. Duk da haka, matakin Eocp na halitta ya fi matakin Eocp mara halitta. Akwai dalilai da za a yi imani da cewa wannan bambanci yana da alaƙa da samuwar biofilms na P. aeruginosa. A kan Hoto na 2d a gaban P. aeruginosa, ƙimar icorr 2707 HDSS ta kai 0.627 μA cm-2, wanda tsari ne na girma fiye da na ikon sarrafa abiotic (0.063 μA cm-2), wanda ya yi daidai da ƙimar Rct da EIS ta auna. A cikin 'yan kwanakin farko, ƙimar impedance a cikin ruwan P. aeruginosa ta ƙaru saboda haɗewar ƙwayoyin P. aeruginosa da samuwar biofilms. Duk da haka, lokacin da biofilm ɗin ya rufe saman samfurin gaba ɗaya, impedance ɗin yana raguwa. Ana kai hari ga Layer mai kariya musamman saboda samuwar biofilms da metabolites na biofilm. Sakamakon haka, juriyar tsatsa ta ragu akan lokaci kuma haɗewar P. aeruginosa ta haifar da tsatsa ta gida. Yanayin da ke cikin yanayin abiotic ya bambanta. Juriyar tsatsa na ikon sarrafa ba tare da ilimin halittu ba ya fi ƙimar da ta dace da samfuran da aka fallasa ga ruwan P. aeruginosa. Bugu da ƙari, don haɗuwa da abiotic, ƙimar Rct 2707 HDSS ta kai 489 kΩ cm2 a rana ta 14, wanda ya ninka ƙimar Rct (32 kΩ cm2) sau 15 a gaban P. aeruginosa. Saboda haka, 2707 HDSS yana da kyakkyawan juriya ga tsatsa a cikin yanayi mara tsafta, amma ba ya jure wa MICs daga biofilms na P. aeruginosa.
Ana iya ganin waɗannan sakamakon daga lanƙwasa na polarization a cikin Fig. 2b. An danganta reshen Anodic da samuwar biofilm na Pseudomonas aeruginosa da halayen iskar shaka na ƙarfe. A wannan yanayin, amsawar cathodic shine rage iskar oxygen. Kasancewar P. aeruginosa ya ƙara yawan tsatsa na yanzu, kusan girman girma fiye da na abiotic control. Wannan yana nuna cewa biofilm na P. aeruginosa yana ƙara tsatsa na gida na 2707 HDSS. Yuan et al.29 sun gano cewa yawan tsatsa na yanzu na Cu-Ni 70/30 ya ƙaru a ƙarƙashin aikin biofilm na P. aeruginosa. Wannan na iya zama saboda biocatalysis na rage iskar oxygen ta hanyar biofilm na Pseudomonas aeruginosa. Wannan lura kuma na iya bayyana MIC 2707 HDSS a cikin wannan aikin. Hakanan akwai ƙarancin iskar oxygen a ƙarƙashin biofilm na aerobic. Saboda haka, ƙin sake wucewa saman ƙarfe tare da iskar oxygen na iya zama wani abu da ke ba da gudummawa ga MIC a cikin wannan aikin.
Dickinson da abokan aikinsa 38 sun ba da shawarar cewa yawan halayen sinadarai da na lantarki na iya shafar kai tsaye ta hanyar aikin metabolism na ƙwayoyin cuta masu narkewa a saman samfurin da kuma yanayin samfuran tsatsa. Kamar yadda aka nuna a Hoto na 5 da Tebur na 5, adadin ƙwayoyin halitta da kauri na biofilm sun ragu bayan kwana 14. Wannan za a iya bayyana shi ta hanyar gaskiyar cewa bayan kwana 14, yawancin ƙwayoyin sessile a saman 2707 HDSS sun mutu saboda ƙarancin sinadarai a cikin matsakaiciyar 2216E ko kuma sakin ions na ƙarfe masu guba daga matrix na 2707 HDSS. Wannan iyakance ne na gwaje-gwajen rukuni.
A cikin wannan aikin, wani fim ɗin P. aeruginosa biofilm ya taimaka wajen rage Cr da Fe a cikin gida a ƙarƙashin biofilm ɗin da ke saman 2707 HDSS (Hoto na 6). Tebur na 6 ya nuna raguwar Fe da Cr a cikin samfurin D idan aka kwatanta da samfurin C, yana nuna cewa Fe da Cr da aka narkar da shi wanda biofilm ɗin P. aeruginosa ya haifar ya ci gaba har tsawon kwanaki 7 na farko. Ana amfani da yanayin 2216E don kwaikwayon yanayin teku. Ya ƙunshi 17700 ppm Cl-, wanda yayi daidai da abun da ke cikin ruwan teku na halitta. Kasancewar 17700 ppm Cl- shine babban dalilin raguwar Cr a cikin samfuran abiotic na kwanaki 7 da 14 da XPS ta bincika. Idan aka kwatanta da samfuran P. aeruginosa, narkewar Cr a cikin samfuran abiotic ya ragu sosai saboda ƙarfin juriyar 2707 HDSS ga chlorine a ƙarƙashin yanayin abiotic. A hoto na 9 ya nuna kasancewar Cr6+ a cikin fim ɗin passivating. Yana iya zama da hannu wajen cire sinadarin chromium daga saman ƙarfe ta hanyar amfani da biofilms na P. aeruginosa, kamar yadda Chen da Clayton suka ba da shawara.
Saboda girman ƙwayoyin cuta, ƙimar pH na matsakaiciyar kafin da bayan noma sun kasance 7.4 da 8.2, bi da bi. Don haka, a ƙasa da biofilm na P. aeruginosa, lalata acid na halitta ba zai iya ba da gudummawa ga wannan aikin ba saboda yawan pH a cikin matsakaiciyar girma. pH na matsakaiciyar sarrafawa mara ilimin halitta bai canza sosai ba (daga farko 7.4 zuwa ƙarshe 7.5) a lokacin gwajin kwanaki 14. Ƙaruwar pH a cikin matsakaicin iri bayan shiryawa ya faru ne saboda aikin metabolism na P. aeruginosa kuma an gano yana da irin wannan tasiri akan pH idan babu tsiri na gwaji.
Kamar yadda aka nuna a Hoto na 7, matsakaicin zurfin ramin da biofilm na P. aeruginosa ya haifar shine 0.69 µm, wanda ya fi na matsakaiciyar abiotic (0.02 µm). Wannan ya yi daidai da bayanan lantarki da aka bayyana a sama. Zurfin ramin 0.69 µm ya fi ƙasa da ƙimar 9.5 µm da aka ruwaito don 2205 DSS a ƙarƙashin irin wannan yanayi. Waɗannan bayanai sun nuna cewa 2707 HDSS yana nuna juriya mafi kyau ga MICs fiye da 2205 DSS. Wannan bai kamata ya zama abin mamaki ba tunda 2707 HDSS yana da matakan Cr mafi girma waɗanda ke ba da tsawon lokaci na passivation, mafi wahalar cire P. aeruginosa, kuma saboda daidaitaccen tsarin sa ba tare da ruwan sama na biyu mai cutarwa ba yana haifar da pitting.
A ƙarshe, an sami ramukan MIC a saman 2707 HDSS a cikin ruwan P. aeruginosa idan aka kwatanta da ƙananan ramuka a cikin yanayin abiotic. Wannan aikin ya nuna cewa 2707 HDSS yana da juriya mafi kyau ga MIC fiye da 2205 DSS, amma ba shi da kariya gaba ɗaya ga MIC saboda biofilm na P. aeruginosa. Waɗannan sakamakon suna taimakawa wajen zaɓar ƙarfe masu dacewa da bakin ƙarfe da tsawon rai ga yanayin ruwa.
Takardar shaidar 2707 HDSS da Makarantar Nazarin Ƙarfe ta Jami'ar Northeastern (NEU) da ke Shenyang, China ta bayar. An nuna sinadarin 2707 HDSS a cikin Jadawali na 1, wanda Sashen Binciken Kayan Aiki da Gwaji na NEU ya yi nazari a kai. An yi wa dukkan samfuran magani don samun maganin tauri a zafin jiki na 1180°C na tsawon awa 1. Kafin gwajin tsatsa, an goge wani siffa mai siffar tsabar kuɗi mai siffar 2707 HDSS mai faɗin saman 1 cm2 zuwa grit 2000 da takardar silicon carbide sannan aka goge shi da foda mai nauyin 0.05 µm Al2O3. An kare gefuna da ƙasa da fenti mara aiki. Bayan bushewa, an wanke samfuran da ruwan da aka cire daga ion kuma an yi musu maganin ethanol 75% (v/v) na tsawon awanni 0.5. Sannan an busar da su ta iska a ƙarƙashin hasken ultraviolet (UV) na tsawon awanni 0.5 kafin amfani.
An sayi nau'in Pseudomonas aeruginosa na ruwa MCCC 1A00099 daga Cibiyar Tarin Al'adu ta Ruwa ta Xiamen (MCCC), China. An noma Pseudomonas aeruginosa a ƙarƙashin yanayin iskar oxygen a zafin digiri 37 a cikin kwalba 250 ml da ƙwayoyin lantarki na gilashi 500 ml ta amfani da ruwan Marine 2216E (Qingdao Hope Biotechnology Co., Ltd., Qingdao, China). Matsakaici ya ƙunshi (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 6NH26NH3, 3.0016 NH3 5.0 peptone, 1.0 yisti da citrate na ƙarfe 0.1. Autoclave a 121°C na minti 20 kafin a yi allurar. A ƙidaya ƙwayoyin sessile da planktonic tare da hemocytometer a ƙarƙashin na'urar hangen nesa mai haske a girman 400x. Yawan farko na planktonic Pseudomonas aeruginosa nan da nan bayan allurar ya kai kimanin ƙwayoyin 106/ml.
An gudanar da gwaje-gwajen lantarki a cikin wani ƙaramin gilashin lantarki mai ƙarfin lantarki uku mai matsakaicin girma na 500 ml. An haɗa takardar platinum da kuma electrode mai cike da calomel (SAE) zuwa reactor ta hanyar capillaries na Luggin da aka cika da gadoji na gishiri, waɗanda suka yi aiki a matsayin electrodes na counter da reference, bi da bi. Don ƙera electrodes masu aiki, an haɗa wayar tagulla mai roba a kowane samfurin kuma an rufe ta da epoxy resin, wanda ya bar kusan 1 cm2 na yanki mara kariya ga electrode mai aiki a gefe ɗaya. A lokacin auna electrochemical, an sanya samfuran a cikin matsakaicin 2216E kuma an ajiye su a yanayin zafi mai ɗorewa (37°C) a cikin wanka na ruwa. An auna OCP, LPR, EIS da bayanan polarization mai yuwuwar amfani da Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., Amurka). An yi rikodin gwaje-gwajen LPR a ƙimar scan na 0.125 mV s-1 a cikin kewayon -5 zuwa 5 mV tare da Eocp da ƙimar samfurin 1 Hz. An yi EIS da igiyar sine a kan kewayon mita tsakanin 0.01 zuwa 10,000 Hz ta amfani da ƙarfin lantarki mai amfani da 5 mV a yanayin Eocp mai ƙarfi. Kafin sharewar da za a iya yi, wayoyin lantarki suna cikin yanayin aiki har sai an kai ga ƙimar karko na ƙarfin tsatsa kyauta. Daga nan aka auna lanƙwasa na polarization daga -0.2 zuwa 1.5 V a matsayin aikin Eocp a ƙimar scan na 0.166 mV/s. An maimaita kowace gwaji sau 3 tare da kuma ba tare da P. aeruginosa ba.
An goge samfuran nazarin ƙarfe ta hanyar injiniya da takardar SiC mai launin ruwan kasa mai girman 2000 sannan aka ƙara goge su da maganin foda na Al2O3 mai girman 0.05 µm don lura da ido. An yi nazarin ƙarfe ta amfani da na'urar hangen nesa ta amfani da na'urar hangen nesa. An ƙera samfuran da maganin potassium hydroxide mai girman 10 wt% 43.
Bayan an gama, an wanke samfuran sau 3 da sinadarin phosphate buffered saline (PBS) (pH 7.4 ± 0.2) sannan aka gyara su da glutaraldehyde 2.5% (v/v) na tsawon awanni 10 don gyara biofilms. Sannan aka bushe su da ethanol mai tsari (50%, 60%, 70%, 80%, 90%, 95% da 100% ta girma) kafin a busar da su ta iska. A ƙarshe, an sanya fim ɗin zinare a saman samfurin don samar da wutar lantarki don lura da SEM. An mayar da hankali kan hotunan SEM akan tabo waɗanda ke da ƙwayoyin P. aeruginosa mafi kunkuntar a saman kowane samfurin. Yi nazarin EDS don nemo abubuwan sinadarai. An yi amfani da na'urar duba laser confocal na Zeiss (CLSM) (LSM 710, Zeiss, Jamus) don auna zurfin ramin. Domin lura da ramukan tsatsa a ƙarƙashin biofilm ɗin, an fara tsaftace samfurin gwajin bisa ga ƙa'idar ƙasa ta ƙasar Sin (CNS) GB/T4334.4-2000 don cire samfuran tsatsa da biofilm daga saman samfurin gwajin.
An yi nazarin X-ray photoelectron spectroscopy (XPS, tsarin nazarin saman ESCALAB250, Thermo VG, Amurka) ta amfani da tushen X-ray monochromatic (layin Aluminum Kα mai kuzari na 1500 eV da ƙarfin 150 W) a cikin nau'ikan kuzarin ɗaurewa 0 a ƙarƙashin yanayin yau da kullun na –1350 eV. An yi rikodin manyan spectra ta amfani da ƙarfin watsawa na 50 eV da mataki na 0.2 eV.
An cire samfuran da aka saka a cikin kwano aka wanke su a hankali da PBS (pH 7.4 ± 0.2) na tsawon 15 s45. Don lura da yuwuwar ƙwayoyin cuta na biofilms akan samfuran, an yi wa biofilms fenti ta amfani da LIVE/DEAD BacLight BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, Amurka). Kayan aikin ya ƙunshi rini biyu masu haske: rini mai haske kore na SYTO-9 da rini mai haske ja na propidium iodide (PI). A cikin CLSM, dige-dige masu haske kore da ja suna wakiltar ƙwayoyin halitta masu rai da matattu, bi da bi. Don yin fenti, an saka 1 ml na cakuda wanda ya ƙunshi 3 µl na SYTO-9 da 3 µl na maganin PI na tsawon mintuna 20 a zafin ɗaki (23°C) a cikin duhu. Bayan haka, an duba samfuran da aka saka a cikin raƙuman ruwa guda biyu (488 nm don ƙwayoyin halitta masu rai da 559 nm don ƙwayoyin halitta masu mutuwa) ta amfani da na'urar Nikon CLSM (C2 Plus, Nikon, Japan). An auna kauri na biofilm a cikin yanayin duba 3D.
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