Muchidzidzo ichi, takaongorora Cu/Ni nanoparticles akagadzirwa mune microcarbon masosi panguva yekubatanidzwa neRF sputtering uye RF-PECVD, pamwe neyenzvimbo yepa plasmon resonance yekuona CO gasi uchishandisa Cu/Ni nanoparticles. Morphology yezvikamu. Surface morphology yakadzidzwa nekuongorora 3D atomic force micrographs uchishandisa mufananidzo kugadzirisa uye fractal/multifractal yekuongorora maitiro. Ongororo yeStatistical yakaitwa pachishandiswa MountainsMap® Premium software ine maviri-nzira ongororo yekusiyana (ANOVA) uye kushoma kwakakosha bvunzo bvunzo. Surface nanostructures ine yemuno uye yepasirese yakananga kugovera. Iyo yekuyedza uye yakateedzera Rutherford backscattering spectra yakasimbisa mhando ye nanoparticles. Iwo masampula achangogadzirwa akabva aiswa kune kabhoni dhimoni chimney uye kushandiswa kwavo segasi sensor kwakaongororwa uchishandisa nzira yenzvimbo yenzvimbo yeplasmon resonance. Kuwedzerwa kwe nickel layer pamusoro pemhangura yemhangura kwakaratidza migumisiro inofadza zvose maererano ne morphology uye kuongorora gasi. Iko kusanganiswa kweyepamusoro stereo ongororo yeakatetepa firimu pamusoro petopography neRutherford backscattering spectroscopy uye spectroscopic ongororo yakasarudzika mundima iyi.
Kukurumidza kusvibiswa kwemhepo mumakumi mashoma emakore apfuura, kunyanya nekuda kwekukurumidza kwemaindasitiri, kwakakurudzira vaongorori kudzidza zvakawanda nezvekukosha kwekuona magasi. Metal nanoparticles (NPs) yakaratidzwa kuva inovimbisa zvinhu zvegasi sensors1,2,3,4 kunyangwe kana ichienzaniswa nemafirimu esimbi akatetepa anokwanisa kurodha pamusoro peplasmon resonance (LSPR), chiri chinhu chinopindirana nemagetsi akasimba uye akasimba mashoma emagetsi. minda5,6,7,8. Sesimbi isingadhure, yakaderera-chepfu, uye inochinja-chinja, mhangura inoonekwa sechinhu chakakosha nemasainzi neindasitiri, kunyanya vanogadzira sensor9. Kune rimwe divi, nickel transition metal catalysts inoita zvirinani pane mamwe macatalysts10. Iko kunozivikanwa kushandiswa kweCu / Ni pa nanoscale kunoita kuti zvive zvakakosha zvikuru, kunyanya nokuti maitiro avo ekugadzirisa haashanduki mushure mekusanganiswa11,12.
Nepo simbi nanoparticles uye kupindirana kwadzo nedielectric svikiro ichiratidza shanduko dzakakura munzvimbo dzepamusoro plasmon resonances, saka dzakashandiswa sezvivharo zvekuvakisa gasi kuona13. Kana iyo inotorwa spectrum ichichinja, izvi zvinoreva kuti zvinhu zvitatu zveresonant wavelength uye / kana kunyura peak intensity uye / kana FWHM inogona kuchinja ne 1, 2, 3, 4. Pazvimiro zvenanostructured, izvo zvinoenderana zvakananga nekukura kwechidimbu, nzvimbo yenzvimbo. plasmon resonance mu nanoparticles, kwete mumafirimu matete, chinhu chinoshanda chekuziva mamolecular. absorption14, sezvakataurwawo naRuiz et al. yakaratidza hukama pakati pezvimedu zvakanaka uye kugona kuona15.
Nezvekuonekwa kwemaziso eCO gasi, zvimwe zvakaumbwa zvinhu zvakaita seAuCo3O416, Au-CuO17 uye Au-YSZ18 zvakataurwa mumabhuku. Tinogona kufunga nezvegoridhe sesimbi yakasarudzika yakaunganidzwa nesimbi okisijeni kuona mamorekuru egasi akaiswa nekemikari pamusoro peiyo composite, asi dambudziko guru nemasensor nderekuita kwadzo patembiricha yekamuri, zvichiita kuti isasvike.
Mumakumi mashoma emakore adarika, atomic force microscopy (AFM) yakashandiswa senzira yepamusoro kuratidza matatu-dimensional surface micromorphology pahigh nanoscale resolution19,20,21,22. Pamusoro pezvo, stereo, fractal/multifractal analysis23,24,25,26, power spectral density (PSD)27 uye Minkowski28 functionals ndiwo maturusi echizvino-zvino ekuratidza chimiro chepamusoro chemafirimu matete.
Muchidzidzo ichi, zvichibva pakutorwa kwenzvimbo yeplasmon resonance (LSPR), acetylene (C2H2) Cu/Ni NP traces yakaiswa pakamuri tembiricha kuti ishandiswe seCO gas sensors. Rutherford backscatter spectroscopy (RBS) yakashandiswa kuongorora kuumbwa uye morphology kubva kumifananidzo yeAFM, uye 3D topographic mepu dzakagadziriswa pachishandiswa MountainsMap® Premium software kudzidza pamusoro isotropy uye ese ekuwedzera micromorphological paramita yepasi microtextures. Nekune rimwe divi, mitsva yesainzi mhedzisiro inoratidzwa inogona kushandiswa kune maindasitiri maitiro uye inofarira zvikuru mukushandiswa kwemakemikari gasi kuona (CO). Mabhuku anoshuma kekutanga kuumbwa, hunhu uye kushandiswa kweiyi nanoparticle.
Firimu rakatetepa reCu/Ni nanoparticles rakagadzirwa neRF sputtering uye RF-PECVD co-deposition ine 13.56 MHz magetsi. Iyo nzira inobva pane reactor ine ma electrode maviri emhando dzakasiyana uye hukuru. Iyo diki isimbi seye electrode ine simba, uye iyo yakakura inodzika pasi kuburikidza nekamuri yesimbi isina tsvina iri chinhambwe che5 cm kubva kune mumwe. Isa iyo SiO 2 substrate uye iyo Cu target mukamuri, wobva wabuda mukamuri kuenda ku103 N/m 2 seyakadzika yekumanikidza pakamuri tembiricha, pinza acetylene gasi mukamuri, uye wozomanikidza kune ambient pressure. Pane zvikonzero zviviri zvakakosha zvekushandisa gasi reacetylene mudanho iri: chekutanga, inoshanda semutakuri gasi rekugadzira plasma, uye chechipiri, kugadzirira nanoparticles mukuteedza huwandu hwekabhoni. Iyo deposition process yakaitwa kwemaminetsi makumi matatu pane yekutanga gasi kudzvanywa uye RF simba re3.5 N/m2 uye 80 W, zvichiteerana. Wobva wapwanya vacuum uye shandura chinangwa kuNi. Iyo deposition process yakadzokororwa pane yekutanga gasi kudzvanywa uye RF simba re2.5 N/m2 uye 150 W, zvichiteerana. Pakupedzisira, mhangura uye nickel nanoparticles akaiswa mumhepo yeacetylene inoumba mhangura / nickel nanostructures. Ona Tafura 1 yemuenzaniso wekugadzirira uye zviziviso.
Mifananidzo ye3D yemasampuli achangobva kugadzirirwa yakanyorwa mu 1 μm × 1 μm square scan nzvimbo uchishandisa nanometer multimode atomic force microscope (Digital Instruments, Santa Barbara, CA) mu-non-contact mode pa scanning speed ye10-20 μm / min. . With. MountainsMap® Premium software yakashandiswa kugadzirisa iyo 3D AFM topographic mepu. Zvinoenderana ne ISO 25178-2: 2012 29,30,31, akati wandei morphological paramita akanyorwa uye kukurukurwa, kureba, musimboti, vhoriyamu, hunhu, basa, nzvimbo uye musanganiswa zvinotsanangurwa.
Ukobvu uye kuumbwa kwemasamples achangobva kugadzirirwa akafungidzirwa pahurongwa hweMeV uchishandisa yakakwirira-simba Rutherford backscattering spectroscopy (RBS). Panyaya yekuongorora gasi, LSPR spectroscopy yakashandiswa uchishandisa UV-Vis spectrometer muwavelength renji kubva pa350 kusvika 850 nm, nepo mumiriri wemuenzaniso waive mune yakavharwa Stainless simbi cuvette ine dhayamita ye5.2 cm uye kureba kwe13.8 cm. pakuchena kwe99.9 % CO gas flow rate (maererano neArian Gas Co. IRSQ standard, 1.6 kusvika 16 l/h kwemasekonzi 180 uye 600 masekondi). Iyi nhanho yakaitwa pakamuri tembiricha, ambient humidity 19% uye fume hood.
Rutherford backscattering spectroscopy senzira yekuparadzira ion ichashandiswa kuongorora kuumbwa kwemafirimu matete. Iyi yakasarudzika nzira inobvumira quantification pasina kushandisa referensi chiyero. RBS ongororo inoyera simba repamusoro (He2+ ions, kureva alpha zvimedu) pahurongwa hweMeV pane sampuli uye He2+ ions yakadzoserwa pakona yakapihwa. Iyo SIMNRA kodhi inobatsira pakuenzanisa mitsara yakatwasuka uye macurves, uye tsamba yayo kune yekuedza RBS spectra inoratidza kunaka kwemasamples akagadzirirwa. Iyo RBS spectrum yeCu / Ni NP sampuli inoratidzwa muMufananidzo 1, apo mutsara mutsvuku ndiyo yekuedza RBS spectrum, uye mutsara webhuruu ndiyo kuenzanisa kwepurogiramu yeSIMNRA, zvinogona kuonekwa kuti mitsetse miviri ye spectral iri mune zvakanaka. chibvumirano. Bango rechiitiko rine simba re1985 keV rakashandiswa kuona zvinhu zviri mumuenzaniso. Ukobvu hwepamusoro hunoita 40 1E15Atom/cm2 ine 86% Ni, 0.10% O2, 0.02% C uye 0.02% Fe. Fe inosanganiswa netsvina muNi target panguva yekupopota. Nheyo dzepamusoro dzeCu neNi dzinoonekwa pa1500 keV, zvichiteerana, uye nhongonya dzeC uye O2 pa426 keV uye 582 keV, zvichiteerana. Iwo Na, Si, uye Fe nhanho 870 keV, 983 keV, 1340 keV, uye 1823 keV, zvichiteerana.
Square 3D topographic AFM mifananidzo yeCu uye Cu/Ni NP firimu inoratidzwa muFig. 2. Mukuwedzera, iyo 2D topography inowanikwa mumufananidzo wega wega inoratidza kuti maNPs akaonekwa pamusoro pemufirimu wepamusoro anobatana kuva spherical shapes, uye iyi morphology yakafanana neyakatsanangurwa naGodselahi naArmand32 naArmand et al.33. Zvisinei, yedu Cu NPs yakanga isina kusanganiswa, uye sampuli ine Cu chete yakaratidza nzvimbo yakanyanyisa yakatsetseka nepamusoro pepamusoro kupfuura iyo yakaoma (Fig. 2a). Pane zvinopesana, mapeji akazaruka paCuNi15 uye CuNi20 samples ane chimiro chakajeka che spherical uye kukwirira kwepamusoro, sezvinoratidzwa nehuwandu hwehupamhi muFig. 2a uye b. Iko kujeka kushanduka kwemufirimu morphology kunoratidza kuti pasi kune akasiyana topographical spatial zvimiro, izvo zvinokanganiswa ne nickel deposition nguva.
AFM mifananidzo yeCu (a), CuNi15 (b), uye CuNi20 (c) mafirimu matete. Mamepu akakodzera e2D, kugoverwa kwekumusoro uye Abbott Firestone macurves akaiswa mumufananidzo wega wega.
Avhareji yezviyo saizi ye nanoparticles yakafungidzirwa kubva padhayamita yekugovera histogram yakawanikwa nekuyera zana nanoparticles uchishandisa Gaussian fit sezvakaratidzwa muFIG. Zvinogona kuonekwa kuti Cu uye CuNi15 vane mavhareji ezviyo zvezviyo (27.7 uye 28.8 nm), nepo CuNi20 ine zviyo zviduku (23.2 nm), iyo iri pedyo nekukosha kwakataurwa naGoselahi et al. 34 (anenge 24 nm). Mune bimetallic systems, nhongonya dzenzvimbo dzepamusoro dzeplasmon resonance dzinogona kushanduka nekuchinja kwekukura kwezviyo35. Panyaya iyi, tinogona kugumisa kuti nguva yakareba yeNi deposition inokanganisa nzvimbo yeplasmonic yeCu / Ni mafirimu akaonda ehurongwa hwedu.
Particle size distribution ye (a) Cu, (b) CuNi15, uye (c) CuNi20 matete mafirimu akawanikwa kubva kuAFM topography.
Bulk morphology inoitawo basa rakakosha mukugadziriswa kwenzvimbo yezvimiro zvetopographic mumafirimu matete. Tafura 2 inodonongodza kureba-kwakavakirwa topographic paramita yakabatana nemepu yeAFM, iyo inogona kutsanangurwa nenguva yakakosha yekurevesa roughness (Sa), skewness (Ssk), uye kurtosis (Sku). Iwo maSa values ari 1.12 (Cu), 3.17 (CuNi15) uye 5.34 nm (CuNi20), zvichiteerana, zvichisimbisa kuti mafirimu anove akaomarara nekuwedzera Ni deposition nguva. Aya maitiro anofananidzwa neaya akambotaurwa naArman et al.33 (1-4 nm), Godselahi et al.34 (1-1.05 nm) uye Zelu et al.36 (1.91-6.32 nm), apo yakafanana sputtering yakaitwa pachishandiswa nzira idzi kuisa mafirimu eCu/Ni NPs. Zvisinei, Ghosh et al.37 akaisa Cu / Ni multilayers ne electrodeposition uye yakashuma yakakwirira roughness values, sezviri pachena muhuwandu hwe13.8 kusvika 36 nm. Izvo zvinofanirwa kucherechedzwa kuti misiyano mukinetics yekuumbwa kwepasi nenzira dzakasiyana dzekuisa dzinogona kutungamirira kuumbwa kwenzvimbo dzine maitiro akasiyana enzvimbo. Zvakadaro, zvinogona kuonekwa kuti nzira yeRF-PECVD inoshanda pakuwana mafirimu eCu/Ni NPs ane hukasha husingapfuuri 6.32 nm.
Kana iri yehurefu hwembiri, iyo yepamusoro-yekurongeka manhamba nguva Ssk uye Sku ine hukama neasymmetry uye yakajairika yekugovera kwehurefu, zvichiteerana. Ese maSsk values akanaka (Ssk> 0), zvichiratidza kureba kwekurudyi muswe38, iyo inogona kusimbiswa nehupamhi hwekugovera chirongwa mune inset 2. Mukuwedzera, ese maprofiles ehurefu aitongwa neinopinza peak 39 (Sku> 3) , kuratidza kuti curve Kugoverwa kwehurefu kwakaderera pane Gaussian bhero curve. Mutsara mutsvuku muhurefu hwekugovera chirongwa ndeye Abbott-Firestone 40 curve, nzira yakakodzera yenhamba yekuongorora yakajairika kugovera data. Mutsetse uyu unowanikwa kubva pahuwandu hwehuwandu hwehupamhi hwehistogram, uko iyo yepamusoro peak uye yakadzika dhishi ine hukama nehushoma hwavo (0%) uye huzhinji (100%) hutsika. Aya maAbbott-Firestone curves ane yakatsetseka S-chimiro pane y-axis uye mune zvese zviitiko zvinoratidza kuwedzera kunofambira mberi kwechikamu chezvinhu zvakayambuka nzvimbo yakafukidzwa, kutanga kubva kune yakakasharara uye yakanyanya kusimba peak. Izvi zvinosimbisa chimiro chepasi chepamusoro, icho chinonyanya kukanganiswa nenguva yekuisa nickel.
Tafura 3 inodonongodza iyo chaiyo ISO morphology paramita yakabatana nenzvimbo yega yega inowanikwa kubva pamifananidzo yeAFM. Zvinonyatso zivikanwa kuti nharaunda kune zvinhu chiyero (Smr) uye iyo counter nharaunda kune zvinhu chiyero (Smc) inzvimbo inoshanda paramita29. Semuenzaniso, mhedzisiro yedu inoratidza kuti dunhu riri pamusoro peyepakati ndege yepasi yakazara yakazara mumafirimu ese (Smr = 100%). Nekudaro, hunhu hweSmr hunowanikwa kubva kwakasiyana hurefu hwenzvimbo inotakura coefficient ye terrain41, sezvo parameter Smc ichizivikanwa. Maitiro eSmc anotsanangurwa nekuwedzera kwehukukutu kubva kuCu → CuNi20, uko kunogona kuonekwa kuti iyo yakanyanya roughness kukosha yakawanikwa yeCuNi20 inopa Smc ~ 13 nm, nepo kukosha kweCu kunenge 8 nm.
Kusanganisa paramita RMS gradient (Sdq) uye yakagadziridzwa interface nharaunda reshiyo (Sdr) maparamita ane hukama nekunyorova uye kuoma. Kubva kuCu → CuNi20, iyo Sdq kukosha kubva pa7 kusvika 21, zvichiratidza kuti kusarongeka kwemafirimu mumafirimu kunowedzera kana Ni layer yaiswa kwemaminitsi makumi maviri. Izvo zvinofanirwa kucherechedzwa kuti iyo pamusoro peCuNi20 haina kufanana neiyo Cu. Mukuwedzera, zvakaonekwa kuti kukosha kweparameter Sdr, yakabatana nekuoma kwepamusoro microtexture, inowedzera kubva kuCu → CuNi20. Maererano nekuongorora kwakaitwa naKamble et al.42, kuoma kwepamusoro microtexture kunowedzera nekuwedzera Sdr, zvichiratidza kuti CuNi20 (Sdr = 945%) ine yakanyanya kuoma pamusoro microstructure kana ichienzaniswa neCu films (Sdr = 229%). . Muchokwadi, shanduko yeiyo microscopic kuomarara kwechimiro inoita basa rakakosha mukugovera uye chimiro chepamusoro pepamusoro, iyo inogona kucherechedzwa kubva kune hunhu paramita ye peak density (Spd) uye arithmetic inoreva peak curvature (Spc). Panyaya iyi, Spd inowedzera kubva kuCu → CuNi20, zvichiratidza kuti nhongonya dzakanyanya kurongeka nekuwedzera kweNi layer ukobvu. Mukuwedzera, Spc inowedzerawo kubva kuCu → CuNi20, zvichiratidza kuti chimiro chepamusoro chepamusoro cheCu sampuli chinowedzera kutenderera (Spc = 612), nepo CuNi20 ichipinza (Spc = 925).
Iyo yakakasharara mbiri yefirimu rega rega inoratidzawo akasiyana epamhepo mapatani munzvimbo dzepamusoro, dzepakati, uye dzemugero dzepamusoro. Kureba kwepakati (Sk), kuderera kwenhongonya (Spk) (pamusoro pepakati), uye dhiri (Svk) (pazasi pepakati) 31,43 maparameter akayerwa perpendicular kune yepasi plane30 uye kuwedzera kubva Cu → CuNi20 nekuda kwe pamusoro roughness Kuwedzera kunokosha . Saizvozvo, peak material (Vmp), core material (Vmc), trough void (Vvv), uye core void vhoriyamu (Vvc) 31 inoratidza maitiro akafanana seanowedzera kukosha kubva kuCu → CuNi20. Maitiro aya anoratidza kuti iyo CuNi20 yepamusoro inogona kubata mvura yakawanda kupfuura mamwe masampuli, ayo ari akanaka, zvichiratidza kuti nzvimbo iyi iri nyore kuisa smear44. Naizvozvo, zvinofanirwa kucherechedzwa kuti sezvo ukobvu hwenickel layer hunowedzera kubva kuCuNi15 → CuNi20, shanduko yeiyo topographic profile inononoka kumashure kwekuchinja kwepamusoro-kurongeka morphological parameters, inokanganisa pamusoro microtexture uye spatial pateni yefirimu.
Ongororo yemhando yepamusoro yekugadzirwa kwemicroscopic yenzvimbo yefirimu yakawanikwa nekugadzira iyo AFM topographic mepu vachishandisa yekushambadzira MountainsMap45 software. Iko kupihwa kunoratidzwa muMufananidzo 4, unoratidza mumiriri groove uye polar plot maererano nechepamusoro. Tafura 4 inoronga slot uye nzvimbo sarudzo. Mifananidzo ye grooves inoratidza kuti sampu inotongwa neyakafanana sisitimu yematanho ane yakataurwa homogeneity ye grooves. Zvisinei, maparamendi ezvose zviri zviviri kudzika kwegorofu (MDF) neavhareji kudzika kwegorofu (MDEF) anowedzera kubva kuCu kusvika kuCuNi20, zvichisimbisa zvakaonekwa kare pamusoro pekugona kweLubricity kweCuNi20. Zvinofanira kucherechedzwa kuti Cu (Fig. 4a) uye CuNi15 (Fig. 4b) samples dzine zvinenge zvikero zvemavara akafanana, izvo zvinoratidza kuti microtexture yeCu film surface haina kuchinja zvikuru mushure mokunge Ni film yakaiswa kune 15 min. Kusiyana neizvi, sampuli yeCuNi20 (Fig. 4c) inoratidza makwinya ane mavara akasiyana-siyana, ayo ane hukama nepamusoro MDF uye MDEF maitiro.
Grooves uye pamusoro isotropy ye microtextures yeCu (a), CuNi15 (b), uye CuNi20 (c) mafirimu.
Iyo polar dhayagiramu mufig. 4 inoratidzawo kuti iyo yepamusoro microtexture yakasiyana. Zvinokosha kuziva kuti kuiswa kweiyo Ni layer inoshandura zvakanyanya mamiriro epamhepo. Iyo yakaverengerwa microtextural isotropy yemasampuli yaive 48% (Cu), 80% (CuNi15), uye 81% (CuNi20). Zvinogona kuoneka kuti kuiswa kweiyo Ni layer kunobatsira pakuumbwa kweiyo isotropic microtexture, nepo imwechete layer Cu firimu ine yakawanda anisotropic pamusoro microtexture. Pamusoro pezvo, iyo yakakura spatial frequencies yeCuNi15 neCuNi20 yakadzikira nekuda kwekureba kwavo kwakakura autocorrelation (Sal) 44 zvichienzaniswa neCu samples. Izvi zvinosanganiswawo nemaitiro akafanana ezviyo anoratidzwa nemasampuli aya (Std = 2.5 ° uye Std = 3.5 °), nepo kukosha kukuru kwakanyorwa kuCu sampuli (Std = 121 °). Zvichienderana nemhedzisiro iyi, mafirimu ese anoratidza kusiyana-refu kwenzvimbo nekuda kwekusiyana morphology, topographic profiles, uye roughness. Nokudaro, migumisiro iyi inoratidza kuti Ni layer deposition time inoita basa rinokosha pakuumbwa kweCuNi bimetallic sputtered surfaces.
Kudzidza maitiro eLSPR eCu/Ni NPs mumhepo patembiricha yekamuri uye pane akasiyana CO gasi fluxes, UV-Vis absorption spectra yakaiswa muwavelength renji ye350-800 nm, sezvakaratidzwa muMufananidzo 5 weCuNi15 uye CuNi20. Nekuunza akasiyana CO gasi kuyerera densities, iyo inoshanda LSPR CuNi15 peak ichava yakafara, kunyura kuchave kwakasimba, uye peak ichachinja (redshift) kuenda kune yakakwirira wavelengths, kubva pa597.5 nm mukuyerera kwemhepo kuenda ku16 L/h 606.0 nm. CO inoyerera kwe180 seconds, 606.5 nm, CO inoyerera 16 l/h kwe600 seconds. Nekune rimwe divi, CuNi20 inoratidza hunhu hwakasiyana, saka kuwedzera kweCO gas kuyerera kunokonzera kudzikira kweLSPR peak wavelength chinzvimbo (blueshift) kubva pa600.0 nm pakuyerera kwemhepo kuenda ku589.5 nm pa16 l/h CO kuyerera kwe180 s. . 16 l/h CO inoyerera kwe600 seconds pa589.1 nm. Sezvakaita neCuNi15, isu tinogona kuona yakafara peak uye yakawedzera kunyura kusimba kweCuNi20. Zvinogona kufungidzirwa kuti nekuwedzera kwehupamhi hweNi layer paCu, pamwe nekuwedzera kwehukuru uye nhamba yeCuNi20 nanoparticles panzvimbo yeCuNi15, Cu uye Ni zvimedu zvinoswedera kune mumwe nemumwe, iyo amplitude yemagetsi oscillations inowedzera. , uye, naizvozvo, kuwanda kunowedzera. zvinoreva kuti: wavelength inoderera, kuchinja kwebhuruu kunoitika.
Nguva yekutumira: Aug-16-2023