Photocatalytic efficiency of ZnFe-mixed metal oxides in correlation with reaction parameters

In the last decade, the interest for the photocatalytic phenomena has rapidly grown due to its great potential for the overall environmental decontamination. Photocatalysts based on ZnFe mixed oxides have been considered to be potentially photocatalyticly efficient in wastewater purification. This investigation is focused on the characterization of the synthesized and thermally treated photocatalysts, on their photocatalytic efficiency in the degradation process of organic dye pollutant Rhodamine B (RhB), as well as on the influence of process parameters on the photocatalytic efficiency. The results showed that the obtained mixed oxides are highly efficient in the RhB degradation. In addition, the pH effect of the reaction system on the photocatalytic activity was observed, which could be explained by the correlation with different textural and structural properties of the photocatalysts

Adsorption kinetics for the removal of methyl orange using adsorbents based on Zn Al-layered double hydroxides

The adsorption phenomena of adsorbents based on ZnAl layered double hydroxides was studied. Methyl orange was used as test pollutant. The emphasis of the study was the analysis of Methyl Orange removal kinetics. The synthesized and thermally treated adsorbents were characterized by X-ray diffraction. The analysis of adsorption kinetics was conducted using the pseudo-second order kinetic model. The results showed that the samples have adsorptive removal properties, particularly the adsorbent derived from thermally treated layered double hydroxides. The findings give an insight into the adsorption phenomena of ZnAl-layered double hydroxides based materials which could be considered as promising adsorbents for the removal of Methyl Orange in wastewaters

Experience in the treatment of some complications of portal hypertension in alcoholic liver cirrhosis

Background/Aim. Portal hypertension (PH) is hemodynamical abnormality associated with the most serious complications of alcoholic liver cirrhosis (ALC): ascites, varices and variceal bleeding. The aim of this study was to determine characteristics of portal hypertension, especially of upper gastrointestinal bleedings in patients with alcoholic liver cirrhosis (ALC). Methods. A total of 237 patients with ALC were observed in a 3-year period. Results. A total of 161 patients (68%) were hospitalized because of PH elements: 86 (36.3%) had upper gastrointestinal bleeding, 75 (31.7%) were decompensated. Only 76 (32%) of the patients had icterus. General mortality was 85 (36%). According to the source of bleeding, 61 (71%) patients bled from varices, and 25 (29%) from other sources with existing varices but non-incriminated for bleeding in 16 (64%) of those patients. Active bleeding or stigmata of recent bleeding were found in 63 (73%) cases. Endoscopic treatment of variceal bleeding along with octreotide applied in 20 (32.78%) patients, just octreotide in 32 (52.46%), and octreotid plus balloon tamponade in 9 (14.75%). According to Child-Pugh classification, 25 (29%) of the bleeding patients were in class A, score 5.4; 43 (50%) in class B, score 7.8; and 18 (21%) in class C, score 10.9. Average hemoglobin level was 93 g/L, hematocrit 0.27, AST 71.52 U/L (normal to 37 U/L), ALT 37.74 U/L (normal to 40 U/L). Until this bleeding episode, 41 (47%) of the patients already bled. In the decompensated patients 3 (4%) were in Child Pugh class A, score 6; 42 (56%) in class B, score 8.3; and 30 (40%) in class C, score 10.6. Until this decompensation episode, 7 (9.3%) patients already bled. Conclusion. Patients with ALC need early detection of varices, primary and secondary profilaxis of variceal bleeding and adequate therapy of ascites. When bleeding occurs, patients need urgent upper endoscopy and intensive treatment

Application of the adsorbent CR-100 for Ammonium Removal: Thermodynamic and Kinetic Studies

Groundwater with increased ammonia concentration is a constant concern regarding the preparation of drinking water. The affinity of ammonia to be adsorbed on the surface of different solid materials significantly influences the selection of its removal process and has been the motivation for this investigation. Crystal-Right™ (CR-100) was used for the removal of ammonia from aqueous solution in batch adsorption procedure. The kinetics of adsorption followed the pseudo-second-order model. The Elovich model suggested that chemisorption rate decreased with the temperature increase. The liquid film diffusion and intra-particle diffusion models revealed that heterogeneous adsorbent surface energy had a particularly pronounced impact on the overall mass transfer rate. The Arrhenius and Eyring’s equations suggested spontaneous and endothermic nature of complex adsorption/ion exchange removal process. The isosteric heat of adsorption revealed that with the increase in surface loading lateral interactions between the adsorbed molecules occurred

Etiology and resistance patterns of bacteria causing ventilator-associated pneumonia in a respiratory intensive care unit

© 2017, Institut za Vojnomedicinske Naucne Informacije/Documentaciju. All Rights Reserved. Background/Aim. Ventilator-associated pneumonia (VAP) incidence, causative pathogens, and resistance patterns are different among countries and intensive care units (ICUs). In Europe, resistant organisms have progressively increased in the last decade. However, there is a lack of data from Serbian ICUs. The aims of this study were to evaluate etiology and antimicrobial resistance for pathogens causing VAP in ICU patients, to examine whether there were differences among pathogens in early-onset and late-onset VAP and to identify mortality in patients with VAP after 30 and 60 days of hospitalization. Methods. A retrospective cohort study was conducted in the respiratory ICU and all adult patients diagnosed with VAP from 2009 to 2014 were included. Results. Gram negative organisms were the major pathogens (80.3%). The most commonly isolated was Acinetobacter spp (59.8%). There was a statistically significant increase in the incidence of infection with Klebsiella pneumoniae (8.9% vs 25.6%; p = 0.019). Extensively drugresistant strains (XDR) were the most common (78.7%). Lateonset VAP was developed in 81.1% of patients without differences among pathogens in comparison with early-onset VAP. Acinetobacter spp was susceptible to tigecycline and colistin with a significant increase in resistance to ampicillin/sulbactam (30.2% vs 58.6%; p = 0.01). Resistance rate of Pseudomonas aeruginosa and Klebsiella pneumoniae to carbapenems was 38% and 11%, respectively. In methicillin-resistant Staphylococcus aureus no resistance was observed against vancomycin and linezolid. There was no difference in mortality rate between patients with earlyonset and late-onset VAP after 30 and 60 days of hospitalization. Conclusion. Gram negative organisms were the primary cause of bacterial VAP of which the most common was the XDR strain of Acinetobacter spp. Patients with early- and late-onset VAP had the same pathogens. There was no difference in mortality between this two group of patients during 60 days of hospitalization

Photocatalytic properties of ZnFe-mixed oxides synthesized via a simple route for water remediation

ZnFe photocatalysts have been increasingly investigated for water remediation due to the high demands in this field, such as activity, toxicity, cost, and stability. The presented study was focused on the simple, safe, non-toxic, and eco-friendly synthesis and characterization of ZnFe-mixed metal oxides in correlation with their functional properties. Photocatalytic performance of these materials was evaluated by rhodamine B photodegradation under simulated solar light irradiation. The synthesized mixed oxides contained hexagonal wurtzite ZnO as the predominant phase, whereas, after thermal treatment, the formation of the spinel-structured ZnFe2O4 phase was observed. The photocatalysts with the additional spinel phase and thermally treated at 300°C and 500°C exhibited superior photocatalytic activity probably due to the highest amount of the ZnFe2O4 spinel phase, favourable mesoporous structure, and an optimal energy band gap of ∼2.30 eV that initiated higher light-harvesting efficiency. The rhodamine B photodegradation followed zero-order kinetics, indicating complete coverage of active sites by the pollutant substrate. Additionally, photocatalysts showed the highest efficiency at the natural pH (6.8), being in accordance with green synthesis principles. Simple, green route assembling synthesis method, high photodegradation efficiency, and good reusability make these ZnFe-mixed oxides great candidates for potential application in practical wastewater treatments

Characterization of macrolide-resistant non-invasive pneumococci in the pre-vaccine era in Serbia

Numerous reports have confirmed that increased macrolide use in the treatment of respiratory tract infection has contributed to the emergence of antibiotic resistance worldwide. Studies have also shown that pneumococcal vaccine can reduce pneumococcal resistance. The aim of this study was to determine the prevalence of co-resistance to penicillin and other antibiotics in macrolide-resistant (MR) non-invasive pneumococcal isolates and to evaluate serotype distribution in resistant strains in the pre-vaccine era in Serbia. About 80% of MR isolates expressed the MLS phenotype with very high resistance to both erythromycin and clindamycin. A total of 132 (84.1%) MR isolates were multiresistant, i.e., they were resistant to erythromycin, penicillin, tetracycline, and trimethoprim–sulfamethoxazole. Among 157 MR pneumococci, 11 different serotypes were found. Four serotypes, 19F, 14, 6B, and 23F, accounted for 77.7% of all MR pneumococcal isolates. Among isolates with the cMLS phenotype, serotypes 19F and 14 were predominant, whereas serotype 6A was the most common among those with the M phenotype, followed by 14. In conclusion, co-resistance to macrolides and penicillin in our non-invasive pneumococcal isolates is high. The majority of tested strains (∼80%) belonged to the four serotypes (19F, 14, 6B, and 23F) that are included in all conjugate vaccine formulations