Immobilization of cesium with alkali-activated blast furnace slag

Alkali-activated binders (AABs), as a promising alternative to Portland cement, are now being used on a commercial scale in various applications around the world, including hazardous and radioactive waste immobilization. In this paper, the leaching resistance, strength, and nanostructural alteration of alkali-activated blast furnace slag (AABFS) doped with 2 % and 5 % cesium were investigated. The addition of cesium caused a significant increase in the compressive strength of AABFS, followed by mild strength reduction after leaching. AABFS can be considered a potentially efficient matrix for cesium immobilization, since the mean leachability index in both cases (2 % and 5 % of Cs added) was above the threshold value of 6. Both doping with Cs and leaching caused the transformation of the AABFS nanostructure. The majority of the aluminum that was released from the C-A-S-H gel due to leaching remained within the AABFS matrix, initiating gel reconstruction: the C-A-S-H gel was converted to C-S-H gel, and an additional N-(C)-A-S-H gel was also formed. Cesium was preferentially associated with the N-(C)-A-S-H gel rather than with the C-A-S-H gel. The results of this research seem to be in good agreement with the Cross-linked Substituted Tobermorite Model (CSTM).

Venous thromboembolism in Croatia - Croatian Cooperative Group for Hematologic Diseases (CROHEM) study

Aim

To analyze the incidence and characteristics of venous thromboembolism (VTE) in Croatia.

Methods

The Croatian Cooperative Group for Hematologic Diseases conducted an observational non-interventional study in 2011. Medical records of patients with newly diagnosed VTE hospitalized in general hospitals in 4 Croatian counties (Šibenik-Knin, Koprivnica-Križevci, Brod-Posavina, and Varaždin County) were reviewed. According to 2011 Census, the population of these counties comprises 13.1% of the Croatian population.

Results

There were 663 patients with VTE; 408 (61.54%) had deep vein thrombosis, 219 (33.03%) had pulmonary embolism, and 36 (5.43%) had both conditions. Median age was 71 years, 290 (43.7%) were men and 373 (56.3%) women. Secondary VTE was found in 57.3% of participants, idiopathic VTE in 42.7%, and recurrent VTE in 11.9%. There were no differences between patients with secondary VTE and patients with idiopathic VTE in disease recurrence and sex. The most frequent causes of secondary VTE were cancer (40.8%), and trauma, surgery, and immobilization (38.2%), while 42.9% patients with secondary VTE had ≥2 causes. There were 8.9% patients ≤45 years; 3.3% with idiopathic or recurrent VTE. Seventy patients (10.6%) died, more of whom had secondary (81.4%) than idiopathic (18.6%) VTE (P < 0.001), and in 50.0% VTE was the main cause of death. Estimated incidence of VTE in Croatia was 1.185 per 1000 people.

Conclusion

Characteristics of VTE in Croatia are similar to those reported in large international studies. Improved thromboprophylaxis during the presence of risk factors for secondary VTE might substantially lower the VTE burden.

Mechanical and microstructural properties of alkali-activated fly ash geopolymers

This paper investigates the properties of geopolymer obtained by alkali-activation of fly ash (FA), i.e. the influence of characteristics of the representative group of FA (class F) from Serbia, as well as that of the nature and concentration of various activators on mechanical and microstructural properties of geopolymers. Aqueous solutions of Ca(OH)(2), NaOH, NaOH+Na(2)CO(3), KOH and sodium silicate (water glass) of various concentrations were used as alkali activators. It was established that the nature and concentration of the activator was the most dominant parameter in the alkali-activation process. In respect of physical characteristics of FA, the key parameter was fineness. The geopolymer based on FA with the highest content of fine particles (<43 microm), showed the highest compressive strength in all cases. Regardless of FA characteristics, nature and concentration of the activator, the alkali-activation products were mainly amorphous. The formation of crystalline phases (zeolites) occurred in some cases, depending on the reaction conditions. The highest compressive strength was obtained using sodium silicate. Together with the increase of sodium silicate SiO(2)/Na(2)O mass ratio, the atomic Si/Al ratio in the reaction products was also increased. Under the experimental conditions of this investigation, high strength was directly related to the high Si/Al ratio.