Addressing the need for standardization of test methods for self-healing concrete: an inter-laboratory study on concrete with macrocapsules.

Development and commercialization of self-healing concrete is hampered due to a lack of standardized test methods. Six inter-laboratory testing programs are being executed by the EU COST action SARCOS, each focusing on test methods for a specific self-healing technique. This paper reports on the comparison of tests for mortar and concrete specimens with polyurethane encapsulated in glass macrocapsules. First, the pre-cracking method was analysed: mortar specimens were cracked in a three-point bending test followed by an active crack width control technique to restrain the crack width up to a predefined value, while the concrete specimens were cracked in a three-point bending setup with a displacement-controlled loading system. Microscopic measurements showed that with the application of the active control technique almost all crack widths were within a narrow predefined range. Conversely, for the concrete specimens the variation on the crack width was higher. After pre-cracking, the self-healing effect was characterized via durability tests: the mortar specimens were tested in a water permeability test and the spread of the healing agent on the crack surfaces was determined, while the concrete specimens were subjected to two capillary water absorption tests, executed with a different type of waterproofing applied on the zone around the crack. The quality of the waterproofing was found to be important, as different results were obtained in each absorption test. For the permeability test, 4 out of 6 labs obtained a comparable flow rate for the reference specimens, yet all 6 labs obtained comparable sealing efficiencies, highlighting the potential for further standardization

The YEATS domain of Taf14 in Saccharomyces cerevisiae has a negative impact on cell growth

The role of a highly conserved YEATS protein motif is explored in the context of the Taf14 protein of Saccharomyces cerevisiae. In S. cerevisiae, Taf14 is a protein physically associated with many critical multisubunit complexes including the general transcription factors TFIID and TFIIF, the chromatin remodeling complexes SWI/SNF, Ino80 and RSC, Mediator and the histone modification enzyme NuA3. Taf14 is a member of the YEATS superfamily, conserved from bacteria to eukaryotes and thought to have a transcription stimulatory activity. However, besides its ubiquitous presence and its links with transcription, little is known about Taf14’s role in the nucleus. We use structure–function and mutational analysis to study the function of Taf14 and its well conserved N-terminal YEATS domain. We show here that the YEATS domain is not necessary for Taf14’s association with these transcription and chromatin remodeling complexes, and that its presence in these complexes is dependent only on its C-terminal domain. Our results also indicate that Taf14’s YEATS domain is not necessary for complementing the synthetic lethality between TAF14 and the general transcription factor TFIIS (encoded by DST1). Furthermore, we present evidence that the YEATS domain of Taf14 has a negative impact on cell growth: its absence enables cells to grow better than wild-type cells under stress conditions, like the microtubule destabilizing drug benomyl. Moreover, cells expressing solely the YEATS domain grow worser than cells expressing any other Taf14 construct tested, including the deletion mutant. Thus, this highly conserved domain should be considered part of a negative regulatory loop in cell growth

A Meta-Analysis of Thyroid-Related Traits Reveals Novel Loci and Gender-Specific Differences in the Regulation of Thyroid Function

Peer reviewe

Fifteen years of inpatient care in an academic division of general internal medicine: 1980-1994. Trends over time in patient's diagnoses, case-severity, case-complexity and mortality rate.

We describe the trends over time in patient's diagnoses, case-complexity, case-severity, length of stay and mortality rate during the last 15 years in an academic division of general internal medicine (GIM). Our study shows that GIM patients presented with a broad spectrum of diseases. Moreover, important changes were observed in the patient characteristics, i.e. a progressive increase in urgent admissions, severe medical conditions and elderly population. This evolution was associated with a significant rise in case-severity and case-complexity which explains the observed increase in hospital mortality rate. These variables should be accounted for when analyzing processes and outcomes of inpatient medical care in internal medicine

Persistent pneumomediastinum and dermatomyositis: a case report and review of the literature.

We describe a 42-year-old man with dermatomyositis and interstitial lung disease who presented with anterior neck pain and dyspnoea. Chest radiographs showed subcutaneous emphysema, pneumomediastinum and diffuse reticulonodular infiltration in both lungs. After the administration of high doses of prednisolone, an improvement of pulmonary function and respiratory symptoms was observed but the pneumomediastinum persists 12 months after diagnosis, and without any complication. We review the cases that have been reported thus far of pneumomediastinum associated with dermatomyositis and discuss the possible mechanisms involved. We conclude that pneumomediastinum is not an uncommon complication of dermatomyositis and that its aetiopathogenesis remains very unclear

Tunable chitosan-alginate capsules for a controlled release of crystallisation inhibitors in mortars

Plasters and renders used in historic monuments are vulnerable to degradation caused by salt weathering. Crystallisation inhibitors (molecules/ions that alter salt crystallisation) mixed into mortars have shown promising results in mitigating salt damage by inhibiting salt crystallisation, promoting salt transport to the evaporating surface, and modifying crystal habit. However, past research suggests that inhibitors easily leach out from mortars, meaning their long-term positive effect is lost. Encapsulation of an inhibitor within a mortar is a potential solution to minimise leaching. Herein, capsules composed of a polyelectrolyte complex of calcium alginate coated in chitosan are investigated for the controlled diffusive release of sodium ferrocyanide, a known NaCl crystallisation inhibitor. Capsules with varying chitosan-calcium alginate ratios are prepared using the extrusion dripping technique. The release of the inhibitor from capsules in solutions of various pH values ranging from 7–13 is investigated. Results show that increasing the capsule’s chitosan to calcium alginate ratio reduces the inhibitor release for all studied solution pH values compared to pure calcium-alginate capsules. Therefore, a controlled inhibitor release can be obtained by tuning the chitosan-alginate ratio. In future, additional tests will be performed to find suitable capsule compositions for optimising their performance when mixed in mortars

EFFECTIVENESS OF SELF-HEALING TECHNOLOGIES IN CEMENT BASED MATERIALS: CONCEPT FOR AN INTER-LABORATORY EXPERIMENTAL EVALUATION BY MULTIPLE TEST METHODS. A PROPOSAL BY COST ACTION CA 15202 SARCOS

The use of self-healing cement-based materials has been recognized as a viable pathway to enhance the durability of reinforced concrete structures and contribute to increase their service life. Research activities have provided enlightening contributions to understand the crack-healing mechanisms and have led to the blooming of stimulated and engineered self-healing technologies, whose effectiveness has been proven in the laboratory and, in a few cases, also scaled up to field applications, with ongoing performance monitoring. Nonetheless, the large variety of methodologies employed to assess the effectiveness of the developed self-healing technologies makes it necessary to provide a unified framework for their validation. This is also instrumental to pave the way towards a consistent incorporation of self-healing concepts into structural design and life-cycle analysis codified approaches and promote their diffusion into the construction market. COST Action CA15202 SARCOS (www.sarcos.eng.cam.ac.uk) has revealed that a reliable assessment of a healing technology has to rely upon multiple measurements, encompassing all the issues recalled above and establishing correlation between the measured crack closure and recovery of the engineering properties of interest. In this paper the concept for a multi-laboratory evaluation of self-healing technologies is presented