Durability aspects of electrochemical realkalisation treatment

Electrochemical realkalisation (ER) is a technique used for the repair of concrete suffering carbonation-induced corrosion of steel reinforcement. It aims at restoring high levels of pH through the application of a temporary cathodic current to steel, and subsequent production of alkalinity at the steel surface; a further mechanism of realkalisation relies on the ingress of an alkaline solution in the concrete through the surface in contact with the anode. ER does not require the replacement of carbonated concrete, if it is not damaged, and so it can be advantageous compared to conventional repair, that usually requires the removal of large amounts of mechanically sound concrete. Although ER was introduced in the 1980s and has been used since then for the repair of carbonated structures, there are still some aspects connected with its application that need further investigation. This paper presents the results of an experimental research aimed at investigating the durability of ER, considering both the realkalisation of carbonated mortar and the protection of reinforcement from corrosion

David Maslanka\u27s \u3ci\u3eDesert Roads, Four Songs for Clarinet and Wind Ensemble\u3c/i\u3e: An Analysis and Performer\u27s Guide

Known primarily as a composer for the wind band, few American composers have received the notoriety and widespread acclaim that David Maslanka has since 1970. His works for wind ensemble are now considered standard repertoire and are played frequently by high school, college-level, and professional ensembles alike. Additionally, his works for chamber groups and soloists have continued to gain in popularity. As of the writing of this document, Maslanka has composed concertos for saxophone, euphonium, flute, marimba, trombone, and piano. Early in 2005, he completed his first large-scale work for solo clarinet with wind ensemble accompaniment: Desert Roads. Desert Roads is comprised of four movements—each with a unique perspective and stylistic approach to the concerto medium. This document begins with a detailed biography of the composer’s life and works. There is an emphasis on the people, places, and events that contributed to Dr. Maslanka’s compositional style. Chapter 2 offers a history of Desert Roads and pays special attention to Dr. Margaret Dees and her leadership in the commissioning of the work. Chapters 3-6 provide analysis and discussion of the structural elements Desert Roads. Additionally, there is discussion of the chorales of J.S. Bach where appropriate. Chapters 3-6 also include graphic illustrations of each movement at the end of the chapter. Chapter 7 offers some concluding remarks and performance considerations for clarinetists, conductors, and scholars. In addition to the customary and required copyright and bibliographic documentation, the appendix of this doctoral document contains a reproduction of the Bach chorales employed within Desert Roads as well as the text from Richard Beale’s On the Subway Platform. Furthermore, the appendix contains the transcription of interviews conducted by the author, and an annotated list of Maslanka’s works for clarinet, giving scholars a context for which to better appreciate Desert Roads. This document is intended to provide readers with a clear, thorough understanding of Desert Roads and contribute to a greater understanding of the music of David Maslanka

What Fits Tim Might Not Fit Tom: Exploring the Impact of User Characteristics on Users’ Experience with Conversational Interaction Modalities

Companies increasingly implement conversational agents (CAs), which can be text- or voice-based. While both interaction modalities have different implications for user interaction, it ultimately depends on the users how they perceive these design options. Research indicates that users’ perception and evaluation of information systems is affected by their individual characteristics – their dispositional traits and needs. To investigate the impact of user characteristics on the user experience with text- and voice-based CAs, we draw on task-technology fit (TTF) theory and develop a research design including a lab experiment. We developed and tested two CAs and conducted a pilot study of the experiment. Initial results indicate that user characteristics influence how users perceive the user experience with text- and voice-based CAs. We expect the results of our research to extend TTF theory to the context of conversational interfaces and guide companies in designing their CAs to deliver a satisfying user experience

The NK cell checkpoint NKG2A maintains expansion capacity of human NK cells

Human natural killer (NK) cells are cytotoxic effector cells that are increasingly harnessed in cancer immunotherapy. NKG2A/CD94 is an inhibitory receptor on NK cells that has established regulatory functions in the direct interaction with target cells when engaged with its ligand, the non-classical HLA class I molecule HLA-E. Here, we confirmed NKG2A as a checkpoint molecule in primary human NK cells and identified a novel role for NKG2A in maintaining NK cell expansion capacity by dampening both proliferative activity and excessive activation-induced cell death. Maintenance of NK cell expansion capacity might contribute to the preferential accumulation of human NKG2A⁺ NK cells after hematopoietic cell transplantation and enrichment of functionally impaired NK cells in human cancers. Functional silencing of NKG2A for cancer immunotherapy is highly attractive but will need to consider that this might also lead to a reduced survival by driving activation-induced cell death in targeted NK cells

The NK cell checkpoint NKG2A maintains expansion capacity of human NK cells

Human natural killer (NK) cells are cytotoxic effector cells that are increasingly harnessed in cancer immunotherapy. NKG2A/CD94 is an inhibitory receptor on NK cells that has established regulatory functions in the direct interaction with target cells when engaged with its ligand, the non-classical HLA class I molecule HLA-E. Here, we confirmed NKG2A as a checkpoint molecule in primary human NK cells and identified a novel role for NKG2A in maintaining NK cell expansion capacity by dampening both proliferative activity and excessive activation-induced cell death. Maintenance of NK cell expansion capacity might contribute to the preferential accumulation of human NKG2A$^{+}$ NK cells after hematopoietic cell transplantation and enrichment of functionally impaired NK cells in human cancers. Functional silencing of NKG2A for cancer immunotherapy is highly attractive but will need to consider that this might also lead to a reduced survival by driving activation-induced cell death in targeted NK cells

Graphite–Cement Paste: A New Coating of Reinforced Concrete Structural Elements for the Application of Electrochemical Anti-Corrosion Treatments

This paper reviews research carried out towards the development of a novel conductive coating for reinforced concrete structures in order to enable the application of electrochemical anti-corrosion treatments. The coating is composed of a hardened paste containing graphite powder and cement. The applied techniques were electrochemical chloride extraction (ECE), cathodic protection (CP), and cathodic prevention, as well as combined treatments such as ECE-CP. This research has demonstrated their efficiency when using the new conductive coating as an anode system. The influence of the shape of the structural elements on the performance of the electrochemical treatments was also studied. Several characteristics of the coating have been determined, such as conductivity, durability, adhesion to the concrete surfaces, and ease of application. The results demonstrate the adequacy of using this coating as the anode for anti-corrosion treatments on reinforced concrete structural elements of different shapes, for the purpose of extending service life.This research was funded by the Spanish Ministerio de Economía y Competitividad (and formerly by the Spanish Ministerio de Ciencia e Innovación) and ERDF (European Regional Development Fund) through projects BIA2010-20548 and MAT2009-10866, and also through the project PROMETEO/2013/035 of Generalitat Valenciana (Spain)

Steel reinforcement corrosion in alkali-activated fly ash mortars

Corrosion of steel rebars in concrete presents one of the main deterioration mechanisms limiting service life of the reinforced structures. The corrosion is accompanied by an expansion of the corrosion products causing high pressures, concrete cracking and finally spalling of a cover layer. Critical chloride concentration, loss of alkalinity and modeling of the steel corrosion are in researchers\u27 spotlight for decades, however reinforcement corrosion in alkali activated materials is insufficiently described and understood yet. In this work, the steel reinforcement corrosion in alkali-activated fly ash mortars is investigated in terms of electrochemical behaviour of the reinforced mortars exposed to aggressive environments such as leaching, carbonation and chloride ingress. A selected geopolymer mixture based on hard coal fly ash activated with sodium hydroxide and sodium silicate solutions is used for the steel reinforcement-corrosion experiments. The formation of passive layer on the steel rebars is observed after approx. two weeks of hardening at laboratory temperature. However, alternative heat-treatment at 80°C for several hours leads to immediate formation of the passive layer as well as to a faster strength gain (80 MPa after 24h at 80°C). Chloride-induced corrosion, leaching and carbonation resistance of the alkali activated fly ash-based concrete is studied, where leaching in deionized water or carbonation under natural conditions (~0.04 % CO2) for 300 days did not lead to corrosion of the embedded steel. On the other hand, accelerated carbonation under 100 % CO2 atmosphere lead to depassivation within two weeks. Please click Additional Files below to see the full abstract