Epidemiology of end‐stage renal disease and hemodialysis treatment in Serbia at the turn of the millennium

The study presents the epidemiological features of patients treated with renal replacement therapy (RRT) in Serbia from 1997 to 2009 and compares the results of hemodialysis treatment in 1999 and 2009. Epidemiological data were obtained from the National Registry of RRT patients and data on hemodialysis treatment from special surveys conducted in 1999 and 2009. Within the period 1997–2009 the incidence of patients on RRT increased from 108 to 179 per million population (pmp), prevalence rose from 435 to 699 pmp, while mortality rate fell from 20.7% to 16.7%. The frequency of patients with glomerulonephritis decreased, while that of patients with diabetes and hypertensive nephropathy increased. In late 2009 there were 5208 patients receiving RRT in Serbia. Within the examined period new hemodialysis and reverse osmosis equipment were purchased, high‐flux dialyzers with synthetic membranes were increasingly used and the number of patients receiving hemodiafiltration increased to 17.6%. Kt/V greater than 1.2 was recorded in 16% of the patients in 1999 but 52% in 2009. Options for correction of anemia and mineral disorders have also improved. The percentage of patients with HbsAg (13.8% vs. 4.8%) as well as anti‐hepatitis C virus antibodies positive patients (23.2% vs. 12.7%) was significantly lower in 2009 than in 1999. Both the incidence and prevalence of RRT patients in Serbia are rising continuously, while the mortality rate is falling. More favorable conditions for dialysis treatment have brought about significant improvement in the results over the last 10 years.     

“Dialdehyde Cellulose” Nanofibers by Electrospinning as Polyvinyl Alcohol Blends: Manufacture and Product Characterization

A nanofiber was obtained by electrospinning of “dialdehyde cellulose” (periodate-oxidized cellulose, DAC) and polyvinyl alcohol (PVA), using only water as the solvent. Celluloses of four different origins were fully oxidized with sodium periodate to water-soluble DAC. Aqueous solution of DAC showed inadequate spinnability regardless of the polymer concentration and the electrospinning conditions used. Addition of PVA improved the solution's viscoelasticity and, consequently, the solution's spinnability. We examined the effects of DAC/PVA composition and electrospinning parameters on fiber morphology. Highly homogeneous nanofibers were prepared from 1:1 up to 2:1 (weight) DAC/PVA blends while samples of lower viscosity or higher relative DAC contents resulted in continuous, beaded fiber networks. Characterization of the electrospun fabrics revealed a highly crosslinked DAC structure reinforced with PVA, strongly interacting through hemiacetal bonds and hydrogen bonding. Fluorescence labeling confirmed the presence of reactive aldehyde functionalities in the electrospun web. The versatile properties of DAC as reactive material can now be imparted on electrospun fiber and nanofiber material – which was not possible so far –further widening the application scope of this interesting cellulose derivative.     

Sphingoid bases in infant formulas

Sphingolipids are a group of lipids present in all eukaryotic cells. They consist of a long-chain sphingoid base that is amide-bound to a fatty acid and a polar group on C-1 sphingosine. Sphingosine is the most widespread base in mammals. The goal of this study is to determine the concentrations of free and total sphingosine and sphinganine in infant formulas and human milk. Following the extraction of sphingolipids, base and acidic hydrolysis was preformed. Sphinganine and sphingosine were determined by means of high-performance liquid chromatography. The results of this research illustrate the differences between the concentrations of sphingoid bases in infant formulas and human milk. On the basis of the obtained results, it can be concluded that despite all efforts made to produce infant formulas as similar to human milk as possible, in terms of their structure and the amount of their constituents, there are differences that could be biologically significant and thus need to be further researched.     

Chemical reduction of nanocrystalline CeO2

The reduction of commercial and mechanochemically processed CeO₂ powders was studied. Nanostructured CeO₂, with the crystallite size of 21 nm and the lattice distortion of 0.37%, was obtained during 60 min of milling in a high-energetic vibratory mill. X-ray diffraction, scanning electron microscopy and Brunauer-Emmett-Teller method were applied to characterize the milled powders. During the thermal treatment at 1200 and 1400 °C in an argon atmosphere the nonstoichiometric CeO_2−x oxides with the defect fluorite structure were formed. Compositions of CeO_2−x oxides were determined according to its lattice parameter. The results showed that the release of oxygen, as well as the rate of reduction, was more effective in nanocrystalline then in the microcrystalline CeO₂, producing at 1200 °C CeO_1.80 and CeO_1.85 oxides, while at 1400 °C were obtained similarly, CeO_1.77 and CeO_1.78, compositions.     

Mathematical model and digital simulation of pulsating overpotential copper electrodeposition

The relationships between the effective current density and the effective overpotential in copper electrodeposition carried out by pulsating overpotential have been analysed experimentally and by digital simulation on the basis of a simple mathematical model. The agreement between the theoretical and experimental results was satisfactory. The quality of the electrodeposit was also studied.     

Time optimal electrodeposition of metals with a pulsating current

A method of input current shape synthesis, applied to the process of the electrodeposition of metals, is given. It is shown that the optimal control theory can be successfully applied to this kind of problem. Essentials of the mathematics of the method and the computer program flow chart are also given.Theory is checked using experiments on the electrodeposition of copper. The agreement between theoretical and experimental results is satisfactory.     

A single nucleotide polymorphism in the sheep kappa-casein coding region

Genetic polymorphisms in CSN3 gene in Pag (Croatia), Sarda (Italy) and Pramenka (Serbia) sheep breeds were investigated. A single nucleotide polymorphism (SNP) was localized by sequence analysis (sequence submitted to GenBank under accession AY237637) relying on an original primer pair. Primers for sequencing (kappa-casF and kappa-casR) were designed on the available CSN3 sequences to amplify the genomic region encoding the major part of the mature protein (exon 4). An SNP was detected at position 237 of the sheep kappa-casein mRNA (reference sequence: GenBank X51822), where a thymine was substituted for a cytosine. The SNP was typed by conventional PCR and SYBR Green I-based real-time PCR. C and T alleles were discriminated using a dedicated set of primers that consisted of one common forward primer (SNP-TC) and two reverse primers (SNP-T and SNP-C), the latter two differing in the 3' end base and in the presence of a 12 bp poly-G tail in SNP-C. The SNP was found in both the heterozygous and the homozygous state in Sarda and Pramenka breeds, and in the heterozygous state only in the Pag breed. The observed allelic frequencies of the SNP were 0.12 in Pag, 0.27 in Sarda and 0.45 in Pramenka.     

SDN Based Mobile Networks: Concepts and Benefits

Mobile Internet traffic is expected to grow faster than the fixed Internet traffic in a near future. Since, today’s broadband networks are approaching theoretical limits in terms of spectral efficiency per link, mobile operators are compelled to seek for new solutions that will be able to accommodate the expected traffic growth and improve their position in the competitive market. Addressing those challenges with current inflexible, not scalable and complex architecture is very hard, if possible at all. Software defined networking (SDN) is a new networking architecture paradigm that holds great promise to overcome many of mentioned limitations and provides required improvements in performance by decoupling control functions from underlying physical infrastructure. In this paper, we explain key reasons for transition to SDN based mobile networks and briefly describe several proposals of design scenario. Special emphasis is placed on SDN’s contribution to more efficient inter-cell interference management, traffic control and network virtualization.