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101.
Synthesis, Structure and Antimicrobial Property of Green Composites from Cellulose, Wool, Hair and Chicken Feather
Chieu Tran, Franja Prosenc, Mladen Franko, Gerald Benzi, 2016, izvirni znanstveni članek

Opis: Novel composites between cellulose (CEL) and keratin (KER) from three different sources (wool, hair and chicken feather) were successfully synthesized in a simple one-step process in which butylmethylimidazolium chloride (BMIm+Cl-), an ionic liquid, was used as the sole solvent. The method is green and recyclable because [BMIm+Cl-] used was recovered for reuse. Spectroscopy (FTIR, XRD) and imaging (SEM) results confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. KER retains some of its secondary structure in the composites. Interestingly, the minor differences in the structure of KER in wool, hair and feather produced pronounced differences in the conformation of their corresponding composites with wool has the highest α-helix content and feather has the lowest content. These results correlate well with mechanical and antimicrobial properties of the composites. Specifically, adding CEL into KER substantially improves mechanical strength of [CEL+KER] composites made from all three different sources, wool, hair and chicken feathers (i.e., [CEL+wool], [CEL+hair] and [CEL+feather]. Since mechanical strength is due to CEL, and CEL has only random structure, [CEL+feather] has, expectedly, the strongest mechanical property because feather has the lowest content of α-helix. Conversely, [CEL+wool] composite has the weakest mechanical strength because wool has the highest α-helix content. All three composites exhibit antibacterial activity against methicillin resistant S. aureus (MRSA). The antibacterial property is due not to CEL but to the protein and strongly depends on the type of the keratin, namely, the bactericidal effect is strongest for feather and weakest for wool. These results together with our previous finding that [CEL+KER] composites can control release of drug such as ciprofloxacin clearly indicate that these composites can potentially be used as wound dressing.
Ključne besede: Green synthesis, Ionic liquid, Keratin, Antibacteria, Wound dressing
Objavljeno v RUNG: 08.06.2016; Ogledov: 5511; Prenosov: 0
Gradivo ima več datotek! Več...

102.
Microfluidic flow injection thermal lens microscopy for high throughput and sensitive analysis of sub-μL samples
Mingqiang Liu, Sara Malovrh, Mladen Franko, 2016, izvirni znanstveni članek

Opis: An analytical method combining microfluidic flow injection analysis (μFIA) with thermal lens microscopy (TLM) was developed for high throughput and sensitive analysis of sub-μL samples. Performance of the μFIA-TLM was validated for detection of hexavalent chromium [Cr(VI)] in water samples. At different sample injection volumes, detection positions and flow rates, influences of the reaction time and the diffusion of Cr-diphenylcarbazone (DPCO) complexes on the μFIA-TLM signal were investigated. Photodegradation of the Cr-DPCO complex was clearly observed when the absorbed photons per Cr-DPCO is above 1600. After optimization of the TLM with respect to rapid flows (up to 10 cm/s), we achieved a limit of detection of 0.6 ng/mL for Cr(VI) in a 50-μm deep channel. Impacts of interfering ions [V(V), Mo(VI), Fe(III)] on the Cr(VI) determination were found to be small. Cr(VI) in real samples from a cement factory were determined and found in good agreement with results of spectrophotometry. This μFIA-TLM shows advantages over its conventional counterpart, such as eliminating additional sample conditioning, reducing over 100 times the sample consumption to sub-μL and over 10 times the time required for one sample injection to a few seconds (up to 20 samples/min). The optimized μFIA-TLM setup can be applied for fast and sensitive analysis of nonfluoresent sub-μL samples in rapidly flowing mediums.
Ključne besede: Spektrometrija TLS, mikroskopija TLM, mikrofluidika, krom (VI)
Objavljeno v RUNG: 01.06.2016; Ogledov: 6378; Prenosov: 277
.pdf Celotno besedilo (828,33 KB)

103.
Optimised calibration procedure for bioanalytical determination of organophosphate pesticides in apple juices by immobilised AChE
Boris Pihlar, Klavdija Mežnar, Mladen Franko, Lea Pogačnik, 2003, izvirni znanstveni članek

Opis: Optimised calibration procedure for bioanalytical determination of organophosphate pesticides in apple juices by immobilised AChE
Ključne besede: analitske metode, biosenzorji, pesticidi, sadni sokovi, analytical techniques, biosensors, FIA, flow injection analysis, pesticides, fruit juices
Objavljeno v RUNG: 17.05.2016; Ogledov: 5940; Prenosov: 18
URL Povezava na celotno besedilo

104.
Thermal Lens Spectrometry: Still a Technique on the Horizon
Mingqiang Liu, Mladen Franko, 2016, objavljeni znanstveni prispevek na konferenci

Opis: In this article the historical development of thermal lens spectrometry (TLS) is briefly reviewed for introduction. In continuation, the emphasis is on the recent progresses of TLS for measurements in ensembled sample cells and in microfluidic flow injection systems. Novel theories, instrumentations and their applications for high sample throughput environmental, chemical and biomedical analysis, particularly in micro space, are presented. Discussions are given on the limitations of present TLS systems, that open new horizons for future progress of this technique, which has already found place among routine techniques for chemical analysis. In the last part, proposals for the future development of TLS toward advanced applications in new research fields are presented.
Ključne besede: Thermal lens spectrometry, Microfluidic chip, Chemical analysis, Environmental monitoring, Biomedical assay
Objavljeno v RUNG: 17.05.2016; Ogledov: 6259; Prenosov: 0
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105.
Thermal lens spectrometry - still a technique on the horizon?
Mladen Franko, 2015

Opis: In 1980’s thermal lens spectrometry (TLS) was still considered as a “spectrometric technique on the horizon” as one can also read from one of the textbooks on spectrochemical analysis of that time. Intensive development of thermal lens instrumentation and methods of chemical analysis and material characterisation has however resulted in substantial progress in this field, which is evident from important instrumental innovations and first commercial instruments (i.e. thermal lens microscopes -TLM) designed for lab-on-a-chip chemistry as well as from novel applications of TLS in various areas, where highly sensitive and rapid chemical analysis of complex samples is needed, including food safety and quality control, environmental analysis and biomedical diagnostics. This presentation is a review of most significant contributions and applications of thermal lens spectrometry, with emphasis on most recent achievements in instrumentation, which culminated into construction of novel optimized TLM instruments, capable of exploiting the tuneability of incoherent light sources and enabled novel applications particularly in micro-fluidics. Based on latest progress relying on bio-analytical assays and micro-fluidic flow injection with TLM detection we have also witnessed firs routine applications of TLS in analytical and diagnostic laboratories, which on wine side actually classifies TLS as a conventional and routine analytical tool, but at the same time opens new horizons for development and applications of this ultrasensitive and rapid spectrometric technique.
Ključne besede: Thermal lens spectrometry, applications, Liquid chromatography, flow injection analysis, bioanalytical methods
Objavljeno v RUNG: 29.03.2016; Ogledov: 8078; Prenosov: 0
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106.
Application of high-performance liquid chromatography combined with ultra-sensitive thermal lens spectrometric detection for simultaneous biliverdin and bilirubin assessment at trace levels in human serum
Mitja Martelanc, Lovro Žiberna, Sabina Passamonti, Mladen Franko, 2016, izvirni znanstveni članek

Opis: We present the applicability of a new ultra sensitive analytical method for the simultaneous determination of biliverdin and bilirubin in human serum. The method comprises isocratic reversed-phase(RP) C18 high-performance liquid chromatography (HPLC) and thermal lens spectrometric detection (TLS)based on excitation by a krypton laser emission line at 407 nm. This method enables the separation of IX-α biliverdin and IX-α bilirubin in 11 min. with limit of detection (LOD) and limit of quantitation (LOQ) for biliverdin of 1.2 nM and 3 nM, and 1nM and 2.8 nM for bilirubin,respectively.In addition, a step-gradient elution was set up, by changing the mobile phase composition, in order to further enhance the sensitivity for bilirubin determination with LOD and LOQ of 0.5 nM and 1.5 nM, respectively. In parallel, an isocraticHPLC-DAD method was developed for benchmarking against HPLC-TLS methods. The LOD and LOQ forbiliverdin were 6 nM and 18 nM, and 2.5 nM and 8nM for bilirubin,respectively. Additionally, both isocratic methods were applied for measuring biliverdin and free bilirubin in human serum samples (from 2 male and 2 female healthy donors). Combining isocratic HPLC method with TLS detector was crucial for first ever biliverdin determination in serum together with simultaneous free bilirubin determination. We showed for the first time the concentration ratio of free bilirubin versus unbound biliverdin in human serum samples.
Ključne besede: Bilirubin, biliverdin, serum, HPLC, TLS
Objavljeno v RUNG: 29.03.2016; Ogledov: 7119; Prenosov: 0
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107.
Določevanje kroma(VI) v mikrofluidnem sistemu z optotermično mikroskopsko detekcijo : /
Sara Malovrh, 2015, diplomsko delo

Opis: Krom (Cr) spada med kovinske onesnaževalce, katerega učinek na okolje je močno odvisen od oksidacijskega stanja. Za ljudi je problematična njegova šestvalentna oblika Cr(VI), ki je rakotvorna, zato je potreba po hitri detekciji Cr(VI) velika. V diplomski nalogi smo preverjali točnost detekcije Cr(VI) ob prisotnosti različnih presežkov motečih elementov kot so šestvalentni molibden (Mo(VI)), petvalentni vanadij (V(V)), trivalentno železo (Fe(III)) in dvovalentno živo srebro (Hg(II)). Po kolorimetrični reakciji čistega standarda Cr(VI) in raztopin motečih elementov z difenilkarbazidom (DPC) smo za meritev uporabili spektrofotometrijsko metodo (SPEC) in mikroskopijo s toplotnimi lečami v mikrofluidnem sistemu za pretočno injekcijsko analizo (µFIA - TLM). Rezultati so pokazali, da največjo napako pri meritvah povzroči prisotnost V(V). Izvedli smo tudi študijo razpada preiskovanih kompleksov Cr-DPCO, Mo-DPCO, V-DPCO, Fe-DPCO in Hg-DPCO v odvisnosti od moči vzbujevalnega laserja v mikrofluidnem TLS sistemu (TLM). Dokazali smo, da je železov kompleks stabilnejši od ostalih preiskovanih ionskih kompleksov, ki so znani kot fotolabilni. Z izračunom spodnje meje določevanja (LOD) za SPEC in TLM metodo smo pokazali, da je TLM, zaradi nižje LOD vrednosti primernejša metoda za detekcijo nizkih koncentracij Cr(VI) v vzorcu. Analiza vzorcev iz Soče in Ljubljanice je prikazala sliko realnega stanja v, potencialno s Cr(VI), onesnaženi reki.
Ključne besede: spektrofotometrija, TLS, TLM, fotolabilnost, moteči elementi
Objavljeno v RUNG: 30.09.2015; Ogledov: 8352; Prenosov: 281
.pdf Celotno besedilo (1,62 MB)

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