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81.
Jasna Simonović Jasna Stevanic Daniela Djikanović Lennart Salmén Ksenija Radotić 《Cellulose (London, England)》2011,18(6):1433-1440
The mechanical and physical properties of wood fibres are dependent on the organisation of their constituent polymers (cellulose,
hemicellulose and lignin). Fourier Transform Infrared (FTIR) microscopy was used to examine the anisotropy of the main wood
polymers in isolated cell wall fragments from branches of maple and Serbian spruce. Polarised FTIR measurements indicated
an anisotropy, i.e. orientation of the cellulose microfibrils that was more or less parallel to the longitudinal axis of the
cell wall. The hemicelluloses, glucomannan and xylan appeared to have a close link to the orientation of the cellulose and,
thus, an orientation more parallel to the axis of the cell wall. An important result is that, in both maple and spruce samples,
lignin was found to be organised in a parallel way in relation to the longitudinal cell wall axis, as well as to the cellulose.
The results show that, despite the different lignin precursors and the different types of hemicelluloses in these two kinds
of wood, lignin has a similar orientation, when it comes to the longitudinal axis of the cell wall. 相似文献
82.
Manuel Algarra Ksenija Radotić Aleksandar Kalauzi Dragosav Mutavdžić Aleksandar Savić José Jiménez-Jiménez Enrique Rodríguez-Castellón Joaquim C.G. Esteves da Silva Juan José Guerrero-González 《Analytica chimica acta》2014
A fluorescent nanocomposite based on the inclusion of CdSe quantum dots in porous phosphate heterostructures, functionalized with amino groups (PPH-NH2@CdSe), was synthesized, characterized and used for fingerprint detection. The main scopes of this work were first to develop a friendly chemical powder for detecting latent fingerprints, especially in non-porous surfaces; their further intercalation in PPH structure enables not to spread the fluorescent nanoparticles, for that reason very good fluorescent images can be obtained. The fingerprints, obtained on different non-porous surfaces such as iron tweezers, mobile telephone screen and magnetic band of a credit card, treated with this powder emit a pale orange luminescence under ultraviolet excitation. A further image processing consists of contrast enhancement that allows obtaining positive matches according to the information supplied from a police database, and showed to be more effective than that obtained with the non-processed images. Experimental results illustrate the effectiveness of proposed methods. 相似文献
83.
Matej Bračič Lourdes Pérez Rosa Infante Martinez-Pardo Ksenija Kogej Silvo Hribernik Olivera Šauperl Lidija Fras Zemljič 《Cellulose (London, England)》2014,21(4):2647-2663
In this investigation, a novel coating for viscose fabric surface modification was developed using a synergistic formulation between a natural antimicrobial cationic surfactant from lysine (MKM) and a biopolymer hyaluronic acid (HA). The interaction between MKM and HA in aqueous solutions, as well as the interactions between their synergistic formulation (HA-MKM) and viscose fabric (CV) were studied using pH-potentiometric titrations’, turbidity measurements, the Kjeldahl method for the determination of nitrogen amounts, attenuated total reflectance fourier transform infrared spectroscopy, and scanning electron microscopy. The hydrophilic and antimicrobial properties of the functionalised CV were examined in order to evaluate its usages for medical applications. The results of the interaction studies showed that MKM and HA interact with each other by forming a precipitate when the binding sites of HA are saturated. The precipitate has a slightly positive charge at neutral pH due to excess binding of the MKM to HA. The excess positive charge was also detected on CV coated with HA-MKM. This was proven to be very beneficial for the antimicrobial properties of the functionalised CV. The antimicrobial tests showed exceptional antimicrobial activity of the functionalised CV against Escherichia Coli, Staphylococcus Aureus, Streptococcus Agalactiae, Candida Albicans, and Candida Glabrata, making the CV fabric highly interesting for potential use in medicine. 相似文献
84.
Ksenija Babić-Samardžija Norman Hackerman Sofija P. Sovilj Vladislava M. Jovanović 《Journal of Solid State Electrochemistry》2008,12(2):155-163
The inhibiting effect of cobalt(III) complexes with macrocyclic ligand cyclam (1,4,8,11-tetraazacyclotetradecane) and β-diketonato ligands have been investigated on iron corrosion in 0.1 M HClO4 by potentiodynamic, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements.
Analysis of the polarization curves and impedance spectra, by adding complex compounds to the acid solution and comparing
with inhibitor-free solution, show corrosion current decrease and charge transfer resistance increase, respectively. Impedance
data are fitted with equivalent circuit models. The stability of the adsorbed film was followed by LPR. Scanning electron
microscopy (SEM) was used to screen physical changes of the reacted surfaces both treated and untreated. The differences in
inhibitor efficiencies depend on the substituent group of the coordinated β-diketone ligand. Structural and electronic properties
of this group of compounds in relation to inhibitor efficiency were analyzed by using the molecular modeling structures and
correlated with previously reported spectroscopy data. 相似文献
85.
We present a study of excited-state behavior of reduced flavin cofactors using femtosecond optical transient absorption spectroscopy. The reduced flavin cofactors studied were in two protonation states: flavin-adenine dinucleotide (FADH2 and FADH-) and flavin-mononucleotide (FMNH2 and FMNH-). We find that FMNH- exhibits multiexponential decay dynamics due to the presence of two bent conformers of the isoalloxazine ring. FMNH2 exhibits an additional fast deactivation component that is assigned to an iminol tautomer. Reduced flavin cofactors also exhibit a long-lived component that is attributed to the semiquinone and the hydrated electron that are produced in photoinduced electron transfer to the solvent. The presence of adenine in FADH2 and FADH- further changes the excited-state dynamics due to intramolecular electron transfer from the isoalloxazine to the adenine moiety of cofactors. This electron transfer is more pronounced in FADH2 due to pi-stacking interactions between two moieties. We further studied cyclobutane thymine dimer (TT-dimer) repair via FADH- and FMNH- and found that the repair is much more efficient in the case of FADH-. These results suggest that the adenine moiety plays a significant role in the TT-dimer repair dynamics. Two possible explanations for the adenine mediation are presented: (i) a two-step electron transfer process, with the initial electron transfer occurring from flavin to adenine moiety of FADH-, followed by a second electron transfer from adenine to TT-dimer; (ii) the preconcentration of TT-dimer molecules around the flavin cofactor due to the hydrophobic nature of the adenine moiety. 相似文献