Mechanical properties of geopolymer mortars in relation to their porous structure

This research dealt with metakaolinite geopolymers of various textures controlled by the addition of a quartz sand in a range of 0–93 wt.%. Mechanical properties were measured to quantify the impact of changing composition on the specimen structure, aimed to the mixture optimizing. The compressive and flexural strengths, Young’s modulus and frost resistance were compared with structure parameters determined by mercury porosimetry. The resulting relations are discussed revealing varying control plots modifying the strengths and frost resistance. The existence of an interfacial transition zone caused by the interaction between the quartz aggregates and the geopolymer was verified to be positively affecting the composite strengths. It has been found that the material of the best mechanical properties underwent the maximal densification of the sand aggregates causing the approaching on the shortest distance with the condition of entirely coating by geopolymer gel. In this manner, the highest interface participation is represented on the composite structure. Besides the high strength, freezing resistance was conditioned by an at least 20% content (within the total porosity) of 1-8 μm large mesopores

Recent developments in bisintercalator natural products

The bisintercalator natural products are a family of nonribosomal peptides possessing a range of biological properties that include antiviral, antibiotic, and anticancer activities. The name bisintercalator is derived from the ability to directly bind to duplex DNA through two planar intercalating moieties. Although 19 members of this family of compounds have been identified over the past 50 years, the biosynthetic genes responsible for the formation of four of these molecules (thiocoraline, SW-163, triostin A, and echinomycin) were identified only recently. This recent progress opens an avenue towards understanding how Nature produces these bisintercalating products and provides the potential to develop and identify novel potent analogous lead compounds for clinical applications. This review discusses the mode of action of bisintercalators and summarizes recent genetic and biochemical insights into their biosynthetic production, analog formation, and possible mechanisms by which resistance to these compounds is achieved by their producing organisms. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 777–790, 2010.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77426/1/21489_ftp.pd

Geopolymer/PEG Hybrid Materials Synthesis and Investigation of the Polymer Influence on Microstructure and Mechanical Behavior

Geopolymers are aluminosilicate inorganic polymers, obtained from the alkali activation of powders containing SiO2+Al2O3>80wt%, mainly proposed as environmentally friendly building materials. In this work, metakaolin-based geopolymers have been prepared and a water-soluble polymer, polyethylene glycol (PEG), has been added in different percentages to obtain organic-inorganic hybrid geopolymers. The influence of both the polymer amount and aging time on the structure and the mechanical behavior of the materials were investigated. FTIR spectroscopy allowed us to follow the evolution of the aluminosilicate framework during the geopolymerization process. This analysis revealed that PEG leads to a network which is rich in Al-O-Si bonds and forms H-bonds with the inorganic phase. SEM microscope showed that the two phases are interpenetrated on micrometric scales. Traction and bending tests have been carried out on appropriate samples to investigate the mechanical behavior of the obtained hybrids, showing that both PEG content and aging time affect the material behavior

Information support of research information interactions of PhD. students in Slovakia

The support of research process in information practices has long attracted attention of information science, especially in terms of digital scholarship and science 2.0. However, there is a need to manage large volumes of digital data in science and new information strategies of young researchers should be designed. The goal of this paper is to report on research of information needs of doctoral students in contexts of information support off digital research data and processes. Based on the concept of information interactions we concentrate on information practices of doctoral students. The study was designed as the follow up of previous research projects on relevance judgments of doctoral students and information ecology of the academic environment. The concept of the study includes the following information interactions: research behavior, information use, information seeking, organization of information, information production, social media. We applied qualitative methodology of semi-structured interviews with doctoral students in different disciplines and visualization of information horizons. Results of data analyses confirm differences in information needs and information strategies in research behavior of doctoral students. Research of dicusssion groups is briefly summarized from the viewpoint of interactive interfaces. Main information problems of doctoral students were identified, namely finding focus, expert support, networking and collaborative information behavior in discussion groups. The final model of information interactions in different disciplines is described and recommendations for information portal design are proposed. Grey information objects in information interactions in digital scholarship are identified and value-added services for the community are also articulated.Includes: Conference preprint, Powerpoint presentation, Abstract and Biographical notesXAInternationa

Cs-Treat Absorber Testing for UKAEA Dounreay.

The performance of Cs-Treat as an absorber of Cs, Sr and co from the DFR waste stream(concentrated sodium and potassium nitrates solution) was examined using a solution pH of 7 - 8 and throughput of 2.5 bed volumes per hour.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Absorber Testing for UKAEA Dounreay DFR4 Test.

The removal of Sr and Co from a simulated DFR waste stream was examined. Ten powdered absorber materials were tested in batch experiments. Ionsiv IE-911, NaTiO-PAN and HTO-PAN granular composite absorbers were tested in the column test.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi