Razvan Stefan

Structural investigations of copper doped B2O3–Bi2O3 glasses with high bismuth oxide content

Raman and infrared spectroscopy have been employed to investigate the 99.5%[xB2O3(1−x)Bi2O3]0.5%CuO glasses with different Bi/B nominal ratios (0.07⩽x⩽0.625) in order to obtain information about the competitive role of B2O3 and Bi2O3 in the formation of the glass network. The glass samples have been prepared by melting at 1100 °C and rapidly cooling at room temperature. In order to relax the structure, to improve the local order and to develop crystalline phases the glass samples were kept at 575 °C for 10 h. The influence of both Bi2O3 and CuO on the vitreous B2O3 network as well as the local order changes around bismuth and boron atoms in as prepared and heat treated samples was studied. Structural modifications occurring in heat treated samples compared to the untreated glasses have been observed.

Vibrational spectroscopy of highly iron doped B2O3-Bi2O3 glass systems

Abstract Glass systems of composition 95%[xB2O3(1−x)Bi2O3]5%Fe2O3 with different Bi/B nominal ratios (0.07⩽x⩽0.90) have been investigated by means of Raman and infrared spectroscopy in order to obtain information about the competitive role of B2O3 and Bi2O3 in the formation of the glass network. The glass samples have been prepared by melting at 1100 °C and rapidly cooling at room temperature. The samples have been further kept at 575 °C for 10 h in order to relax the glasses structure as well as to improve the local order and to develop the new formed crystalline phases. The influence of both Bi2O3 and Fe2O3 on the vitreous B2O3 network as well as the local order changes around bismuth and boron atoms in as prepared and heat-treated samples have been studied. Structural modifications occurring in the heat-treated samples compared to the untreated glasses have been pointed out.

The effect of the housing system on the welfare quality of dairy cows

The aim of this study was to assess the effect of the housing systems (loose vs tie-stall) on the welfare of dairy cows and to test the hypothesis that dairy cows in loose housing systems have a better welfare quality than those kept in tie-stalls. Sixty commercial dairy farms (30 with loose and 30 with tie-stall housing system) were selected for evaluation, using mainly animal-based measures, as the applied Welfare Quality® protocol allows it. A total number of 2624 milking cows were assessed in the winter period. There were significant differences between the two housing systems for the majority of the parameters within the four welfare principles. Significant differences were also found in terms of the mean scores of the welfare criteria and principles, with the majority pointing out the loose system as better. Based on the scores of the four principles, most of the farms with loose housing were classified as enhanced, while the majority of the tie-stall farms were acceptable. The results show that the welfare quality of dairy cows is greatly influenced by the housing system, and that the loose system is more advantageous when it comes to the feeding, housing and behaviour of the dairy cow.

Strain dependent UV degradation of Escherichia coli DNA monitored by Fourier transform infrared spectroscopy

In this work we present a method for detection of DNA isolated from nonpathogenic Escherichia coli strains, respectively. Untreated and UV irradiated bacterial DNAs were analyzed by FT-IR spectroscopy, to investigate their screening characteristic features and their structural radiotolerance at 253.7nm. FT-IR spectra, providing a high molecular structural information, have been analyzed in the wavenumber range 800-1800cm(-1). FT-IR signatures, spectroscopic band assignments and structural interpretations of these DNAs are reported. Also, UV damage at the DNA molecular level is of interest. Strain dependent UV degradation of DNA from E. coli has been observed. Particularly, alterations in nucleic acid bases, base pairing and base stacking have been found. Also changes in the DNA conformation and deoxyribose were detected. Based on this work, specific E. coli DNA-ligand interactions, drug development and vaccine design for a better understanding of the infection mechanism caused by an interference between pathogenic and nonpathogenic bacteria and for a better control of disease, respectively, might be further investigated using Fourier transform infrared spectroscopy. Besides, understanding the pathways for UV damaged DNA response, like nucleic acids repair mechanisms is appreciated.

Fourier transform infrared spectroscopy of DNA from Borrelia burgdorferi sensu lato and Ixodes ricinus ticks

In this work we present a method for detection of motile and immotile Borrelia burgdorferi genomic DNA, in relation with infectious and noninfectious spirochetes. An FT-IR study of DNA isolated from B. burgdorferi sensu lato strains and from positive and negative Ixodes ricinus ticks, respectively, is reported. Motile bacterial cells from the species B. burgdorferi sensu stricto, Borrelia garinii and Borrelia afzelii were of interest. Also, FT-IR absorbance spectra of DNA from immotile spirochetes of B. burgdorferi sensu stricto, in the absence and presence of different antibiotics (doxycycline, erythromycin, gentamicin, penicillin V or phenoxymethylpenicillin, tetracycline, respectively) were investigated. FT-IR spectra, providing a high molecular structural information, have been analyzed in the wavenumber range 400-1800 cm(-1). FT-IR signatures, spectroscopic band assignments and structural interpretations of these DNAs are reported. Spectral differences between FT-IR absorbances of DNAs from motile bacterial cells and immotile spirochetes, respectively, have been found. Particularly, alterations of the sugar-phosphate B-form chain in the case of DNA from Borrelia immotile cells, as compared with DNA from B. burgdorferi sensu lato motile cells have been observed. Based on this work, specific B. burgdorferi sensu lato and I. ricinus DNA-ligand interactions, respectively, might be further investigated using Fourier transform infrared spectroscopy.

Fluorophores advanced glycation end products (AGEs)-to-NADH ratio is predictor for diabetic chronic kidney and cardiovascular disease

AIMS An imbalance in advanced glycation end products (AGEs) and NADH formation has been associated with diabetic chronic kidney disease (CKD) and cardiovascular disease (CVD). No data have been reported on simultaneous measurement of AGEs and NADH in type 2 diabetes (T2DM) patients. We aimed to compare AGEs, NADH and the AGEs-to-NADH ratio in T2DM and controls, and to assess its relationship with diabetic CKD and CVD. MATERIAL AND METHODS In this cross-sectional study, we measured serum AGEs (370/435nm) and NADH (370/460nm) in T2DM patients (n=63) and controls (n=25) using fluorescence spectroscopy. The AGEs-to-NADH ratio was analyzed according to diabetic CKD and CVD. RESULTS We found significantly higher AGEs-to-NADH ratio in T2DM compared to controls. The AGEs-to-NADH ratio was significantly associated with triglycerides, blood glucose, HDL-cholesterol, estimated glomerular filtration rate. The AGEs-to-NADH ratio was a significant predictor for the presence of diabetic CKD and CVD when using ROC curves. Multivariate analysis showed that triglycerides and the presence of T2DM were predictors for the AGEs-to-NADH ratio. CONCLUSIONS These findings suggest that the fluorophores AGEs-to-NADH ratio could be a new biomarker for the presence of diabetic CKD and CVD.

Characterization of the Structural Properties of Zinc Phosphate Glass Ceramics Doped with Manganese Ions Following Thermal Treatment

ABSTRACT Glasses of the MnOx · (P2O5)40 · (ZnO)60−x system were prepared by the melt-quenching technique and thermally treated for 2 h at 650°C. To describe the influence of thermal treatment on zinc phosphate glass matrix doped with manganese ions, X-ray diffraction and infrared spectroscopy were used. The X-ray diffraction patterns revealed that the degree of crystallinity gradually decreased with increasing MnO content in the samples up to 5 mol% of MnO2. The manganese ions were also shown to be captured in the vitreous phase. The infrared spectra confirmed that the glass network underwent changes following thermal treatment. The spectra of thermally treated samples contained new peaks and the infrared bands become narrower compared to those of the untreated samples.