Activated ductile CFRP NSMR strengthening

Significant strengthening of concrete structures can be obtained when using adhesively-bonded carbon fiber-reinforced polymer (CFRP) systems. Challenges related to such strengthening methods are; however, the brittle concrete delamination failure, reduced warning, and the consequent inefficient use of the CFRP. A novel ductile near-surface mounted reinforcement (NSMR) CFRP strengthening system with a high CFRP utilization is introduced in this paper. It is hypothesized that the tailored ductile enclosure wedge (EW) end anchors, in combination with low E-modulus and high elongation adhesive, can provide significant strengthening and ductility control. Five concrete T-beams were strengthened using the novel system with a CFRP rod activation stress of approximately 980 MPa. The beam responses were compared to identical epoxy-bonded NSMR strengthened and un-strengthened beams. The linear elastic response was identical to the epoxy-bonded NSMR strengthened beam. In addition, the average deflection and yielding regimes were improved by 220% and 300% (average values), respectively, with an ultimate capacity comparable to the epoxy-bonded NSMR strengthened beam. Reproducible and predictable strengthening effect seems obtainable, where a good correlation between the results and applied theory was reached. The brittle failure modes were prevented, where concrete compression failure and frontal overload anchor failure were experienced when failure was initiated.The funding source do not wish to be revealed as stated in this section

Tetra­kis(μ-pivalato-κ2 O:O′)bis­[(2-methyl­pyridine-κN)iron(II)](Fe—Fe)

The asymmetric unit of the title compound, [Fe2(C5H9O2)4(C6H7N)2], contains one unique Fe-atom site located close to a centre of symmetry which generates the mol­ecular dimer. The two Fe atoms are bridged by four carboxyl­ate groups and are each coordinated by a mol­ecule of 2-picoline. Electron counting and the 18-electron rule suggest that a chemical single bond is likely to exist between the two Fe atoms, which are separated by a distance of 2.8576 (4) Å. This bond completes an approximately octa­hedral coordination environment around each Fe atom

Challenges Related to Probabilistic Decision Analysis for Bridge Testing and Reclassification

This paper reviews historical developments and recent challenges in full scale bridge testing and introduces results- and hypotheses related to an ongoing bridge testing research project. This research project encompasses full scale bridge testing in conjunction with bearing capacity analysis as well as related contact- and non-contact monitoring procedures combined with a decision analytical approach. Results from the first steps of the project, focusing on full scale load testing of bridges, are presented. The next part approaches the interfaces between three project areas namely the bearing capacity analysis, the utilization of monitoring procedures and a decision analytical approach. The proposed probabilistic decision analysis approach is described for two scenarios: (1) The decision support for the actual proof load test providing decision rules for a safe and efficient in-situ test and (2) for the identification of efficient strategies for the bridge reclassification accounting for modeling, simulation, and monitoring information. The paper concludes with a summary highlighting deemed challenges in the used approaches

Monoclinic paracetamol vs. paracetamol-4,4'-bipyridine co-crystal; what is the difference? a charge density study

Paracetamol (PCM) has two well-documented polymorphic forms at room temperature; monoclinic Form I is more stable than the other orthorhombic Form II. Form II exhibits improved tabletting properties compared to Form I due to low shearing forces; however, difficulties in its manufacture have limited its use in industrial manufacture. Previous studies have found that the introduction of a co-former to form co-crystals would allow the PCM molecule to exist in a conformation similar to that of the orthorhombic form while being more stable at room temperature. Experimental charge density analysis of the paracetamol-4,4′-bipyridine (PCM-44BP) co-crystal system, and its constituent molecules, has been carried out to examine the forces that drive the formation and stabilisation of the co-crystal, while allowing PCM to maintain a packing motif similar to that found in Form II. It is hoped studies on this well-known compound will help apply the knowledge gained to other drug molecules that are less successful. The PCM molecules in the co-crystal were found to exhibit similar packing motifs to that found in Form I, however, intercalation of the 44BP molecule between the PCM layers resulted in a shallower angle between molecular planes, which could result in the required lateral shear. Topological analysis identified more weak interactions in the co-crystal compared to the individual molecules, thus allowing for greater stability as evidenced by the lattice energies. Weak interactions in the PCM-44BP co-crystal were found to range in strength from 4.08–84.33 kJ mol−1, and this variety allowed the PCM-44BP planes to be held together, while a weak π–π interaction (15.14 kJ mol−1) allowed lateral shear to occur, thus mimicking the planes found in Form II PCM and offering the possibility of improved tabletting properties. A comparison of integrated atomic charges between partitions of the PCM molecules in the single and co-crystal found that the hydroxyl and amide groups were involved in greater hydrogen bonding in the co-crystal, resulting in a charge redistribution across the molecule evidenced by a larger molecular dipole moment (µ = 12.34D). These findings, in addition to the co-crystal having the largest lattice energy, form a potential basis with which to predict that the co-crystal exhibits improved solubility and stability profiles. It is anticipated that these findings will contribute to improvements in the formulation and other physical properties of PCM and other pharmaceutical compounds