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Abstract: This review presents recent advances in the non-enzymatic electrochemical detection and quantification of pesticides, focusing on the use of nanomaterial-based electrode modifiers and their corresponding analytical response. The use of bare glassy carbon electrodes, carbon paste electrodes, screen-printed electrodes, and other electrodes in this research area is presented. The sensors were modified with single nanomaterials, a binary composite, or triple and multiple nanocomposites applied to the electrodes’ surfaces using various application techniques. Regardless of the type of electrode used and the class of pesticides analysed, carbon-based nanomaterials, metal, and metal oxide nanoparticles are investigated mainly for electrochemical analysis because they have a high surface-to-volume ratio and, thus, a large effective area, high conductivity, and (electro)- chemical stability. This work demonstrates the progress made in recent years in the non-enzymatic electrochemical analysis of pesticides. The need for simultaneous detection of multiple pesticides with high sensitivity, low limit of detection, high precision, and high accuracy remains a challenge in analytical chemistry.
Keywords: electroanalysis, non-enzymatic sensors, nanomaterials, pesticides
Published in DKUM: 15.05.2025; Views: 0; Downloads: 0
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Abstract: Uvod: Možganska kap je globalni zdravstveni problem, ki je vodilni vzrok invalidnosti in drugi najpogostejši vzrok smrti po vsem svetu. Zgodnje prepoznavanje simptomov je ključno za zmanjšanje tveganja trajnih poškodb. Uporaba predbolnišničnih presejalnih orodij lahko pomaga pri hitrejši obravnavi in oskrbi. Zgodnja prepoznava in zdravljenje možganske kapi bistveno izboljša izid in rehabilitacijo bolnikov. Pomembna je ozaveščenost javnosti in ustrezna usposobljenost zdravstvenega osebja za prepoznavanje simptomov, kar omogoča hitrejšo oskrbo in zmanjšuje tveganje za trajne posledice. Metode: Izvedli smo sistematični pregled literature z metodo pregleda, analize in sinteze ter metodo kompilacije. Iskanje je potekalo v različnih podatkovnih bazah. Končni izbor člankov smo ocenili z orodjem Joanna Briggs Institutes. Rezultati: Skupno smo pridobili 406 zadetkov. Po odstranitvi duplikatov ter pregledu naslovov in povzetkov smo izbrali 12 člankov za končno analizo. Za prikaz poteka pregleda literature smo uporabili PRISMA-diagram. Končni nabor člankov smo razvrstili po hierarhiji dokazov ter jih kritično ocenili. Razprava in zaključek: Raziskave o prepoznavanju možganske kapi v predbolnišničnem okolju so pokazale kompleksnost tega področja. Za to se uporabljajo različne lestvice, vsaka s svojimi prednostmi in omejitvami. Pomembno je izobraževanje izvajalcev za učinkovito uporabo teh orodij.
Keywords: možganska kap, lestvice za nevrološko oceno bolnika, predbolnišnično okolje
Published in DKUM: 06.01.2025; Views: 0; Downloads: 51
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Abstract: Clostridioides difficile (Clostridium difficile) infection (CDI) is one of the main public health concerns in adults, while children under 2 years of age are often colonized asymptomatically. In both adults and children, CDI is strongly associated with disturbances in gut microbiota. In this study, an in-vitro model of children gut microbiota was challenged with vegetative cells or a conditioned media of six different toxigenic C. difficile strains belonging to the ribotypes 027, 078, and 176. In the presence of C. difficile or conditioned medium the children gut microbiota diversity decreased and all main phyla (Bacteroidetes, Firmicutes, and Proteobacteria) were affected. The NMR metabolic spectra divided C. difficile exposed children gut microbiota into three clusters. The grouping correlated with nine metabolites (short chain fatty acids, ethanol, phenolic acids and tyramine). All strains were able to grow in the presence of children gut microbiota and showed a high sporulation rate of up to 57%. This high sporulation rate in combination with high asymptomatic carriage in children could contribute to the understanding of the reported role of children in C. difficile transmissions.
Published in DKUM: 17.06.2024; Views: 213; Downloads: 13
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Abstract: The aim of this Master's thesis was to find a mathematical correlation between various fan momentum fields for a fan which is used for cooling the underhood area of a car. The correlation had to link a known momentum field to all possible momentum fields related to fan rotation speed and car velocity. With this correlation, new alternative fan steering strategies can be used to cool the vehicle underhood area. An already functioning RBM (Rigid Body Motion) simulation was used as a base, since it already gave satisfying results in the past. With this simulation file, several tests were run to ensure that the results really converge nicely. In this way it was established that the results are accurate enough for further use. After obtaining the results, a set of 30 simulation files was calculated. The simulations were a combination of different fan rotation speeds and car velocities. After the set was done, the results were analysed using various computer software (Star-CCM+, MS Excel and Matlab). It was concluded that a polynomial approach for the momentum field was a suitable option but to add some additional complexity, surface equations were used. To obtain the equations, tables with different results were put into Matlab and the program did the rest. The result were two sets of three surface equations with x and y values. In both cases, x represented the rotation speed of the fan and y represented the car velocity in one case and the delta pressure between two evaluation surfaces in the other. After that it was time to implement the newly acquired surface equations in a Star-CCM+ simulation file. The old simulation file was again used as a base, but new field functions were put in with the help of which the UDMS (User Defined Momentum Source) is being changed. Both types of surface equations were tested and calculated. In the end, it was decided to go with the one where the delta pressure on two evaluation surfaces is being used as the y value. One surface was placed in front of the fan and the other after the fan. The final step was to test different fan steering strategies. The usual cooling procedure consists of a phase where the fan cools for a specific amount of time with a defined rotation speed and then turns off. Temperatures on critical points around the engine and in the underhood area of the car are being looked at as a result. The first strategy was to run the fan at the same speed as usual, but gradually slow it down in uniform steps so that the shut down time remains the same. With this approach, the highest temperature values were actually lower than usual, but certain temperature probes became warmer as the fan speed decreased. Nevertheless, the temperatures at the end were very similar. The second tested strategy was inspired by the idea of potentially saving some battery energy if we could somehow manage to cool the underhood area quicker. In this case, the fan ran for a short time at a high rotation speed and after that at a slightly lower speed. Then it was turned off for a few minutes and subsequently switched back on. The maximum temperature in this scenario reached even higher values. The reason for this was that the fan blew warm air toward certain measurement points, causing them to heat up further. The temperatures at the end of the simulation were similar to those in the previous two cases. In conclusion, it is indeed possible to steer a fan momentum field with the help of field functions and equations which describe the relationship between different fan rotation speeds and car velocities.
Keywords: fan, momentum, RBM, CFD, thermal soak
Published in DKUM: 02.04.2024; Views: 225; Downloads: 0
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Abstract: Magistrska naloga prikazuje uporabo in primerjavo različnih načinov merjenja s tehniko mikroskopije na atomsko silo (AFM). Ta analizna tehnika temelji na fizikalni interakciji tipala s površino vzorca in omogoča proučevanje topografije in mehanskih lastnostih vzorca na njegovi površini. V nalogi so podrobno predstavljeni in proučevani kontaktni način delovanja, način potrkavanja in način merjenja prečnih sil. Kontaktni način AFM je osnovni način delovanja za proučevanje topografskih značilnosti površine vzorcev. S pomočjo kontaktnega načina delovanja smo proučevali enakomerno porazdeljene valjaste strukture na površini kalibracijskega standarda HS 100MG. Na podlagi pridobljenih rezultatov smo določili višino in premer teh struktur in opazili boljšo točnost pri določevanju višine topografskih ovir z manjšanjem analiziranega območja. Poleg tega smo kontaktni način uporabili za proučevanje zelo ravne površine vzorca nerjavnega jekla AISI 316L z določeno vrednostjo aritmetične srednje hrapavosti 1,04 nm, na preiskovanem območju lateralnih dimenzij 5,00 µm ∙ 5,00 µm. Kot drugi način delovanja AFM smo proučevali uporabo načina potrkavanja. V primeru analize kalibracijskega standarda HS 100MG, v primerjavi s kontaktnim načinom, je ta način delovanja pokazal boljšo točnost določevanja višine topografskih ovir na izbranih preiskovanih območjih, kar pomeni, da je ta način primernejši za vzorce z visokimi in ostrimi višinskimi prehodi na večjih preiskovanih območjih. Slednje pripisujemo načinu delovanja osciliranja tipala nad površino vzorca. Analiza vzorca nerjavnega jekla je z možnostjo beleženja faze oscilacije tipala prikazala dodatne informacije o mehanskih lastnostih površine vzorca, kar predstavlja veliko prednost v primerjavi s kontaktnim načinom merjenja. Z načinom merjenja prečnih sil smo poleg osnovnih topografskih značilnosti površine proučevali tudi razliko v trenju na površini vzorca nerjavnega jekla, kar predstavlja pomembno prednost v primerjavi z načinom potrkavanja in kontaktnim načinom uporabe, kjer slednje ni mogoče.
Keywords: mikroskopija na atomsko silo, AFM, kontaktni način merjenja, način s potrkavanjem, način merjenja prečnih sil
Published in DKUM: 18.07.2023; Views: 450; Downloads: 97
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