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EN
Amorphous lead metaborate (Pb(BO2)2∙H2O) nanostructures were synthesized by a simpl and cost-effective synthesis method which is based on precipitation of lead ions using boric acid/sodium hydroxide buffer (pH 9.2) in the presence of polyethylene glycol (PEG). Scanning electron microscopy images showed that the average particle size is 30±9 nm and the particle shape is mostly spherical. The chemical formulation of (Pb(BO2)2∙H2O) was confirmed by infrared spectroscopy, inductively coupled plasma and thermal gravimetric analysis (TGA). The percentage of PEG molecules on the particle surface equal to 2.5 % was determined by TGA. Optical reflectance measurement was performed by UV-Vis spectroscopy. Based on the Kubelka-Munk function, it was calculated that the (Pb(BO2)2∙H2O) nanostructures have a direct band gap of 4.6 eV.
PL
Ścieki pochodzące z przemysłu syntezy chemicznej oczyszczano metodą osadu czynnego w reaktorze SBR. Jako układ porównawczy zastosowano drugi reaktor, w którym oczyszczano ścieki komunalne. Ścieki przemysłowe okazały się znacznie mniej podatne na biodegradację zanieczyszczeń organicznych niż ścieki komunalne. Ponadto ścieki przemysłowe miały negatywny wpływ na proces nitryfikacji, co objawiało się mniejszą efektywnością usuwania azotu ogólnego w porównaniu ze ściekami komunalnymi. Korzystnym rozwiązaniem byłoby wspólne oczyszczanie tych dwóch rodzajów ścieków.
EN
Industrial wastewater was treated with H₂SO₄ or Ca(OH)₂ to adjust pH 7-8.5 and with a Fe salt to coagulate the suspension and then mixed with activated sludge. The municipal wastewater was processed as a ref. The study was carried out for 39 days. A substantial decrease in ammonium N concn. and an increase in the nitrate N concn. were obsd. in both wastewaters. A decrease in COD and BOD was also evidenced. The municipal wastewater showed high ability to nitrification.
PL
Oceniano wpływ ścieków pochodzących z przemysłu syntezy chemicznej na fizyczne i biochemiczne właściwości osadu czynnego. Jako układ porównawczy zastosowano drugi reaktor, w którym oczyszczano ścieki komunalne. W układzie oczyszczającym ścieki przemysłowe obserwowano obniżenie aktywności oddechowej osadu czynnego, świadczące o zachwianiu procesów biochemicznych, znaczne zmniejszenie wartości indeksu objętościowego osadu oraz postępujące rozdrobnienie kłaczków świadczące o ich początkującym rozpadzie. W porównaniu z układem odniesienia, kłaczki osadu "przemysłowego" miały luźniejszą strukturę i bardzo małą zawartość bakterii nitkowatych, które stanowią "szkielet" nadający kłaczkom odpowiednią spoistość i wytrzymałość mechaniczną.
EN
Industrial and municipal wastewaters were studied for properties of activated sludge. In the industrial wastewater, a decrease in respiratory activity (O₂ uptake rate) of activated sludge (as an evidence of disorder of biochem. processes) and a significant redn. in sludge vol. index were obsd. The presence of a large no. of very small flocs indicated the beginning of their breakup. The flocs of "industrial" activated sludge had a looser structure and a smaller no. of filamentous bacteria than that in municipal sludge.
EN
NiO–Al2O3 nanocomposite has been synthesized by mixing combustion synthesized powders. The nanocomposite is an effective anode/anode functional layer for intermediate temperature solid oxide fuel cells. The TEM of NiO and Al2O3 revealed spherical particles of 30 nm and platelets of 70 nm, respectively. The XRD analysis of NiO– Al2O3 composite sintered at 900 °C showed presence of cubic NiO and rhombohedral α- Al2O3 which were chemically stable. However, above 1200 °C Ni Al2O4 started to appear. The conductivity of NiO– Al2O3 was the highest in hydrogen (4.3 × 10–3 S/cm at 600 °C). In biogas, the conductivity was 3.2 × 10–3S/cm with the activation energy of 0.67 eV. The stability of the composite in biogas was also examined.
5
EN
The most important component of bacterial cell walls especially Gram-positive bacteria is peptidoglycan, called also murein, PGN. The first time this synonym was used in 1964 by Weidel and Pelzer [1]. Peptidoglycan is present in the outer layer of the cytoplasmic membrane and its structure. The structure of peptidoglycan depends on the bacteria strain. It is estimated that in Gram-negative bacteria, it occupies only about 10–20% of the total area of the cell wall, when in Gram-positive bacteria it is 50 and up to 90% of all space. Problems with isolation with high purity of biological material shows the need for developing techniques for chemical synthesis of peptidoglycan fragments and their analogs. In past few years there has been a growing interest within the synthesis of compounds glycoprotein (glycopeptides, peptidoglycan, etc.). As a basis for the construction of cell walls of many bacteria. Despite intensive research and gain significant knowledge of the physical and biological, chemical synthesis or biosynthesis (Fig. 5 and 6) of peptidoglycan, not so far failed to unambiguously determine its three-dimensional structure. The works of Kelman and Rogers [15] and Dimitriev [20] nearer picture of its structure. However, the time to develop in vivo visualization of cell structure it will be difficult to identify correctly peptidoglycan three-dimensional structure. Due to the important biological roles of murein, many research centers have taken to attempt their chemical synthesis. For biological research began to use chemically synthesized peptidoglycan fragments which guaranteed both uniform and a certain structure. An important roles in the development of methods of chemical synthesis of peptidoglycan had H. Chowdhury work, Fig. 8 [35], Hesek, Fig. 9 and 10 [36, 37], Dziarskiego [38] and Boneca [39] and Inamury [34, 40].
6
Content available remote Green synthesis and characterization of Ag1/2Al1/2TiO3 nanoceramics
EN
Single phase silver aluminum titanate (Ag1/2Al1/2)TiO3, later called AAT, nanoceramic powder (particle size 2 to 7.5 nm) was synthesized by a low-cost, green and reproducible tartaric acid gel process. X-ray, FT-IR, energy dispersive X-ray and high resolution transmission electron microscopy analyses were performed to ascertain the formation of AAT nanoceramics. X-ray diffraction data analysis indicated the formation of monoclinic structure having the space group P2/m(10). UV-Vis study revealed the surface plasmon resonance at 296 nm. Dielectric study revealed that AAT nanoceramics could be a suitable candidate for capacitor applications and meets the specifications for “Z7R” of Class I dielectrics of Electronic Industries Association. Complex impedance analyses suggested the dielectric relaxation to be of non-Debye type. To find a correlation between the response of the real system and idealized model circuit composed of discrete electrical components, the model fittings were performed using the impedance data. Electric modulus studies supported the hopping type of conduction in AAT. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in AAT. The ac conductivity data were used to evaluate the density of states at Fermi level and minimum hopping length of the compound.
EN
V2O3 and amorphous carbon composites (V2O3/C composites) with different morphologies (e.g. nanospheres, nanorods and nanosheets) were, for the first time, successfully synthesized by a facile hydrothermal route and subsequent calcination. The as-obtained samples were characterized by X-ray powder diffraction (XRD), energy dispersive spectrometery (EDS), elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The morphology of V2O3/C composites could be easily controlled by varying the reaction time, and, as a result, V2O3/C composites with nanospheres, nanorods and nanosheets were selectively synthesized. Furthermore, the phase transition property of V2O3/C composites was measured by differential scanning calorimetry (DSC), suggesting that V2O3/C composites exhibit the phase transition similar to V2O3, which could expand the potential applications of materials related to V2O3 in the future.
EN
Silver colloidal nanoparticles were prepared according to the chemical reduction method in which the ascorbic acid was used as a reducing agent and sodium citrate as a stabilizing agent. The absorption spectra of all prepared samples obtained using the UV-Vis spectrophotometer showed a surface plasmon peak at a wavelength of about 420 nm. The size of the silver nanoparticles was controlled by changing the pH values of the reaction system. At high pH, smaller size silver nanoparticles were obtained compared to low pH values. This difference can be attributed to the difference in the reduction rate of the precursor. In addition to the inverse proportionality between the size and the pH value it is clear that increasing the pH value enables us to obtain spherical nanoparticles while at low pH, rods and triangular particle shapes were formed. Poor balance between nucleation and growth processes could be the cause of this result.
EN
BaTi1-xNbxO3 compounds (with x = 0.0, 0.01, 0.03, 0.06, and 0.09) were synthesized by rotary-hydrothermal (RH) method. The process was conducted at 180 °C for 5 hours in a Teflon vessel that was rotated at a speed of 160 rpm during the hydrothermal reaction. The effects of donor concentration on the structure and properties of BaTi1-xNbxO3 compounds were investigated. The experiments for the BaTiO3±Nb2O3 system produced by a solid state reaction at high temperature at different concentrations of niobium, with the use of RH processing have not been reported in previous works. For the phase evolution studies, X-ray diffraction patterns (XRD) were analyzed and Raman spectroscopy measurements were performed. The transmission electron microscope (TEM) and the field emission scanning electron microscope (FE-SEM) images were taken for the detailed analysis of the grain size, surface and morphology of the compound.
EN
This paper describes the growth of Cd doped ZnO thin films on a glass substrate via sol-gel spin coating technique. The effect of Cd doping on ZnO thin films was investigated using X-ray diffraction (XRD), UV-Vis spectroscopy, photoluminescence spectroscopy, I-V characteristics and field emission scanning electron microscopy (FESEM). X-ray diffraction patterns showed that the films have preferred orientation along (002) plane with hexagonal wurtzite structure. The average crystallite sizes decreased from 24 nm to 9 nm, upon increasing of Cd doping. The films transmittance was found to be very high (92 to 95 %) in the visible region of solar spectrum. The optical band gap of ZnO and Cd doped ZnO thin films was calculated using the transmittance spectra and was found to be in the range of 3.30 to 2.77 eV. On increasing Cd concentration in ZnO binary system, the absorption edge of the films showed the red shifting. Photoluminescence spectra of the films showed the characteristic band edge emission centred over 377 to 448 nm. Electrical characterization revealed that the films had semiconducting and light sensitive behaviour.
11
EN
We report here the structural and electrical properties of Zn0:95M0:05O ceramic varistors, M = Zn, Ni and Fe. The samples were tested for phase purity and structural morphology by using X-Ray diffraction XRD and scanning electron microscope SEM techniques. The current-voltage characteristics J-E were obtained by dc electrical measurements in the temperature range of 300 – 500 K. Addition of doping did not influence the hexagonal wurtzite structure of ZnO ceramics. Furthermore, the lattice parameters ratio c/a for hexagonal distortion and the length of the bond parallel to the c axis, u were nearly unaffected. The average grain size was decreased from 1.57 μm for ZnO to 1.19 μm for Ni sample and to 1.22 μm for Fe sample. The breakdown field EB was decreased as the temperature increased, in the following order: Fe > Zn > Ni. The nonlinear region was clearly observed for all samples as the temperature increased up to 400 K and completely disappeared with further increase of temperature up to 500 K. The values of nonlinear coefficient, a were between 1.16 and 42 for all samples, in the following order: Fe > Zn > Ni. Moreover, the electrical conductivity s was gradually increased as the temperature increased up to 500 K, in the following order: Ni > Zn > Fe. On the other hand, the activation energies were 0.194 eV, 0.136 and 0.223 eV for all samples, in the following order: Fe, Zn and Ni. These results have been discussed in terms of valence states, magnetic moment and thermo-ionic emission, which were produced by the doping, and controlling the potential barrier of ZnO.
EN
Polycrystalline Ca1xLax(Ti0:5Fe0:5)O3 were prepared by the standard solid state reaction technique. Pellet shaped samples prepared from each composition were sintered at 1573 K for 5 h. The X-ray diffraction analysis indicated the formation of a single-phase orthorhombic structure. The lattice parameters as well as densities increased but the average grain sizes decreased with the increase of La content. The dielectric measurements were carried out at room temperature as a function of frequency and composition. The experimental results revealed that dielectric constant (e0) decreased but dielectric loss (tand) and ac electrical conductivity (sac) increased as frequency increased. The composition dependence of e0 and tand indicated that they decreased with the increase of La content. The sac was derived from the dielectric measurements and it is concluded that the conduction in the present samples is due to mixed polarons hopping.
PL
W artykule przedstawiono i omówiono wybrane metody otrzymywania nano tlenku cynku. W części I opisano właściwości nano tlenku cynku oraz metody jego otrzymywania. Porównane zostały metody syntez w celu wybrania najbardziej optymalnej do otrzymywania nano tlenku cynku. W kolejnych częściach artykułu przedstawione zostaną wyniki otrzymywania nano tlenku cynku domieszkowanego wybranymi jonami metali - manganu (+II), kobaltu (+II) oraz glinu (+III).
EN
The paper contents the presentation and discussion of selected methods of obtaining nano zinc oxide. The first part of the paper describes the zinc oxide properties and methods of the synthesis. The synthesis methods were compared in order to select the most optimal for obtaining of nano zinc oxide. In subsequent parts of the article the results of obtaining nano zinc oxide doped with selected metal ions - manganese (+II), cobalt (+II) and aluminum (+III) will be described.
14
Content available remote Conduction in nanostructured La1=x Sr x FeO3 (0 <= x <= 1)
EN
We investigated electrical properties of nanostructured La1?x Sr x FeO3 (0 <= x <= 1) from 300 K-400 K. The nanostructured La1-x Sr x FeO3 (0 <= x <= 1) was synthesized by citrate gel method requiring no pH control. X-ray diffraction pattern showed that single phase LaFeO3 with an orthorhombic structure was formed. The structure changed into rhombohedral for x = 0.5 and it became cubic for x = 1.0. For x <= 0.5, our material showed non-linear current-voltage characteristics and for x > 0.5 it showed linear current-voltage characteristics. Poole Frenkel type conduction mechanism was found to be operative in LaFeO3 from 300 K-400 K. The experimental values of field-lowering coefficient were by 2.56-6.41 times higher than the predicted value and were attributed to the presence of localized fields. The increase in conductance with Sr content was due to formation of Fe4+ ions in addition to Fe3+ with the increase in Sr content. Impedance spectroscopy and ac conductivity analysis of La1-x Sr x FeO3 (0 <= x <= 1) was also carried out in the temperature range from 300 K-400 K and frequency was varied from 20 Hz - 2 MHz. The ac conduction followed the correlated barrier hopping model in La0.9Sr0.1FeO3.
15
Content available Kinetics of nanocrystalline iron nitriding
EN
Nitriding of nanocrystalline iron was studied under the atmosphere of pure ammonia and in the mixtures of ammonia - hydrogen - nitrogen at temperatures between 350°C and 500°C using thermogravimetry and x-ray diffraction. Three stages of nitriding were observed and have been ascribed to the following schematic reactions: (1) α-Fe → γ-Fe4N, (2) γ- Fe4N → ε - Fe3N and (3) ε - Fe3N → ε - Fe2N. The products of these reactions appeared in the nitrided nanocrystalline iron not sequentially but co-existed at certain reaction ranges. The dependence of a reaction rate for each nitriding stage on partial pressure of ammonia is linear. Moreover, a minimal ammonia partial pressure is required to initiate the nitriding at each stage.
EN
A facile process is developed for the synthesis of pure vanadium(III) oxide by thermal reduction of vanadium pentoxide (V2O5) in ammonia gas. The process of thermal reduction of V2O5 was optimized by experiments and by modeling of thermodynamic parameters. The obtained V2O3 was characterized by X-ray diffraction, X-ray photoelectron spectrometry, scanning electron microscopy and thermogravimetric analysis. The experimental results indicated that crystal particles of pure V2O3 were successfully synthesized within a short reaction period of 1 h and at a relatively low temperature of 903 K. The content of V2O3 in the product sample higher than 99 wt. %. The grain size of V2O3 ranged from several hundred nanometers to several micrometers. The morphologies of the V2O3 particles were micrometer layers in nanometer sheet structure.
EN
Yttria stabilized zirconia powders were synthesized by the reverse microemulsion method. Powders were calcined from 600 °C to 1000 °C and sintered at 1450 °C. Crystalline properties and microstructure of samples were characterized by X-ray diffraction and scanning electron microscopy, respectively. Oxygen ionic conductivity was measured by electrochemical impedance spectroscopy. Sizes of yttria stabilized zirconia particles calcined at 1000 °C are lower than 100 nm, and approximately, 1 žm grain was obtained after sintering at 1450 °C.
EN
Syntheses of TiO2 derived nanostructures have been conducted at 210 °C by hydrothermal reaction of commercial TiO2-P25 (Degussa, Germany) in 10 M NaOH aqueous solution. High purity of the asproduced material was confirmed by scanning and transmission electron microscope analyses. The crystallographic structure, as well as the optical and vibronic properties of this material were examined by X-ray diffraction, diffuse reflectance (DR) UV-Vis, resonance Raman spectroscopic methods, respectively. Detailed analysis of the phase composition revealed that the rod-like structures are made up of sodium tetratitanate (Na2Ti4O9). It was also observed that acid treatment of the material (hydrothermal reaction) led to a decrease in the diameters of the nanorods. Finally, the photocatalytic activity of the investigated nanostructures was examined, by observing the reaction photocatalytic decolourisation of two organic dyes (Reactive Red 198 and Reactive Black 5) under UV-light irradiation.
EN
Cyclic, 5-membered derivatives of three- and tetracoordinated phosphorus constitute an important group of organophosphorus compounds in light of their increased reactivity towards nucleophilic reagents. This surprising reactivity is caused by steric strain present in 5-membered heterocyclic ring, which is then released on formation of reaction intermediates possessing pentacovalent phosphorus atom. This problem was thoroughly analyzed by Westheimer in his classical paper [13]. The title cyclic compounds found an application in the chemical synthesis of biophosphates such as phospholipid derivatives [15-17, 19-21] or nucleoside phosphates [14, 18], however, in spite of numerous efforts (especially by the groups of Ugi and Ramirez) their applicability to efficient formation of internucleotide linkage was rather limited [22-26]. Further development of this matter was achieved by Stec and coworkers [27], who in 1991 applied appropriately protected P-chiral nucleoside- -3'-O-(2-thiono-1,3,2-oksathiaphospholane)s for the synthesis of stereoregular oligo(nucleoside phosphorothioate)s. In fact, the oxathiaphospholane method was for many years a unique successful approach to stereocontrolled synthesis of phosphorothioate analogs of oligonucleotides. The method was later modified and applied for preparation of other phosphorothioate analogs of nucleotides [29-36], including compounds not containing sulphur [37-39]. Further modification led to so called dithiaphospholane approach, allowing an efficient synthesis of oligo(nucleoside phosphorodithioate)s [40] and other phosphorodithioate analogs of nucleotides [41-44]. An alternative approach to the synthesis of stereoregular oligo(nucleoside phosphorothioate)s, involving an application of P-chiral nucleoside oxazaphospholidine derivatives had at first a limited success (Agrawal et al. [45-47], Beaucage et al. [48]), however, recent achievements of Wada et al. [49] made compounds of this series efficient precursors for stereocontrolled synthesis of phosphorothioate analogs of oligonucleotides.
PL
Wzrost zapotrzebowania na energię oraz brak alternatywy dla paliw kopalnych, jako głównego surowca do jej produkcji, wymusza działania zmierzające do ograniczania emisji dwutlenku węgla oraz poszukiwanie metod jego zagospodarowania. W artykule przedstawiono uzupełniające dla metod składo­wania w formacjach geologicznych sposoby zagospodarowania dwutlenku węgla, bazujące na koncep­cjach synergii elektrowni węglowych, elektrowni jądrowej/wiatrowej/słonecznej i rafinerii wytwarzającej paliwa syntetyczne, metodach wykorzystywania dwutlenku węgla w syntezie chemicznej oraz składowa­nia w postaci hydratów.
EN
An inereasing cnergy demand and the unauestionable leading role of fossil fuels in the energy mix enforce activities aiming at carbon dioxidc emission reduction and new methods of its disposal. In the paper methods complementary to the seauestration of carbon dioxide in geological formations based on the concepts of synergy between coal power plants, nu clear/wind/solar power plants and refineries producing synthetic fuels as well as methods of carbon dioxide utilization in chemical synthesis and storage in the form of hydrates are presented.
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