LIMESTONE - AN INERT MODEL SYSTEM OF CEMENT?

The adsorption of small organic anions like those of benzoate, tartrate, citrate and glutamate on Portland composite cements СЕМ II and CEM III can be influenced by the present limestone (industrial СаСОз). Therefore, the replacement of ordinary Portland cement СЕМ I is not a trivial matter, although using these materials reduces the cement production and hence the C02 emission providing the solution of an up-to date environmental problem. A systematic study is shown here by zeta potential determination on the CaC03 suspension containing the organic anions. The effect of increasing pH leas' further considered and correlated to the adsorption on CaC03 surface. The study gives an insight on the compatibility between cement and organic additives in presence of limestone that has very similar surface properties to cement

GLOBAL WARMING AND CONSTRUCTION ASPECTS

The manufacture of cements with several main constituents is of particular importance with regard to reducing climatically relevant CO2 emissions in the cement industry. This ecological aspect is not the only argument in favor of Portland composite cements. They are also viable alternatives to Portland cement from the technical point of view. Substitution of ordinary Portland cement (CEM I) by Portland composite cements (CEM II) and (CEM III), which clearly possess different chemical and mineralogical compositions, results in changes of their reaction behavior with additives like superplasticizers. A common admixture to CEM I in that sense is limestone (industrial CaCO3). Its interaction with polycarboxylates is ignored and its inertness is taken for granted. This study provides a systematic approach in order to better understand the interaction of these polymeric superplasticizers with CaCO3 by adsorption and zeta potential measurements. The results give some fundamental understanding in how far the cement industry can reduce the production of cement clinker by replacing it with limestone as admixture and consequently the CO2-emission is reduced, which is of high political and environmental interest

The Effect of COVID-19 on the Performance of Listed Firms: Do the governments’ policies and vaccination rates play a role? Evidence from countries in the Middle East and North Africa

This study uses a quantitative approach to estimate the empirical results of COVID-19, stringency index, and vaccination rates on the stock returns of Bahrain, Egypt, Morocco, Oman, Qatar, Saudi Arabia, Tunisia, and UAE. Additionally, the researcher included firm-specific variables such as liquidity and leverage, total capital, employees, and date of incorporation. Total capital and employees were used as proxies for company size and for whether the firm is capital intensive or not, while date of incorporation was used as a proxy for company age. Additionally, the researcher created interaction strings between COVID-19 cases and stringency index, COVID- 19 cases and vaccines, COVID-19 deaths and stringency index, and COVID-19 deaths and vaccines. To test whether these variables affect the stock returns, the researcher ran a Hausmann test to determine whether a fixed effect method or a random effect method is more appropriate to the panel data. The P-value was significant, and hence the researcher used a fixed-effect method. Moreover, the researcher used a Chow test to test whether a structural change existed pre-COVID versus during COVID-19, and the p-value was significant, and hence the researcher concluded the existence of a structural change. The results of the study indicate that COVID-19 cases and stringency index negatively affect the stock returns of listed firms in the MENA region. Moreover, vaccination rates positively affect stock returns by a higher magnitude than that of COVID-19 cases or stringency index. Firm-specific variables such as liquidity, leverage, total capital, total employees, and date of incorporation play a role in the returns of listed firms in the MENA region when the returns are regressed on the number of COVID-19 reported cases. Furthermore, COVID- 19 had a negative effect on stock returns of firms operating in the financial services, energy, power and utilities, tourism, healthcare and pharmaceuticals, chemicals, multi-utilities, logistics, construction and machinery, textiles, apparel and luxury goods, and insurance industries. Furthermore, government policies were able to countereffect the negative effect of COVID-19 deaths on stock returns for each of the 10 industries. The COVID-19 effect on the stock returns was greater than the government policies effect on stock returns for Morocco, Oman, Qatar, Saudi Arabia, and UAE at different significance levels. Vaccination rates have a positive effect on stock returns with a magnitude higher than the coefficients of COVID-19 cases or stringency index. The string variable between COVID-19 cases and vaccination rates is positive, implying that the positive effect of vaccination rates on the stock returns was able to countereffect the negative effect of COVID-19 cases on stock returns

Understanding Wettability through Zeta Potential Measurements

Traditional wettability measurement practices, introduced as early as the late 1950s, are still perceived as reliable industrial methods for characterizing wettability. These techniques, in contrast to the contact angle method, provide indices that can quantitatively describe the degree of wetting state. Nevertheless, these approaches can determine the current state of wettability, subject to limitations. By employing the zeta potential measurements technique, a complete wettability profile is derived. In this chapter, the theory behind this technique is discussed. A case study is presented where the wettability of limestone rock is investigated, as crude oil and asphaltenic solutions of varying concentration are added to the limestone-water suspension. Findings of this study are discussed with the possible mechanism in effect when wettability alteration is observed

The Impact of Islamic Religiosity on Perceived Discrimination, Coping, and Psychological Outcomes

Title from PDF of title page, viewed July 27, 2022Dissertation advisor: Chrisanthia BrownVitaIncludes bibliographical references (pages 127-147)Thesis (Ph.D)--School of Education, Social Work, and Psychological Sciences. University of Missouri--Kansas City, 2022The present study examined the moderating effects of Islamic religiosity on the relationship between racial-ethnic discrimination, religious prejudice, environmental prejudice, religious coping, perceived stress, and Islam’s effect on well-being. Through Amazon’s Mechanical Turk, 875 participants met screening requirements and completed the online survey. Participants completed measures of discrimination (i.e., racial-ethnic, religious prejudice, and environmental prejudice), religious coping (i.e., positive religious coping and negative religious coping), religiosity, well-being, and perceived stress. Analysis revealed that positive and negative religious coping mediated the relationship between the three forms of discrimination and perceived stress. However, positive religious coping mediated the relationship between the three forms of discrimination and Islam’s effect on well-being, and negative religious coping only mediated the relationship between religious prejudice and Islam’s effect on well-being. Religiosity was found to significantly moderate the relationship between positive religious coping and perceived stress and Islam’s effect on well-being. Keywords: Islamic religiosity, religious discrimination, religious coping, well-being, perceived stressChapter 1 -- Chapter 2 -- Appendix A. Inclusion Criteria -- Appendix B. Racial-Ethnic Discrimination -- Appendix C. Religious Discrimination -- Appendix D. Religious Coping -- Appendix E. Perceived Stress -- Appendix F. Well-Being -- Appendix G. Religiosity -- Appendix H. Demographic Questionnair

Studying the effect of high substrate temperature on the microstructure of vacuum evaporated TAPC: C60 organic solar thin films

Organic solar cells (OSCs), also known as organic photovoltaics (OPVs), are an emerging solar cell technology composed of carbon-based, organic molecules, which convert energy from the sun into electricity. Key for their performance is the microstructure of the light-absorbing organic bulk heterojunction. To study this, organic solar films composed of both fullerene C60 as electron acceptor and different mole percentages of di-[4-(N,N-di-p-tolyl-amino)-phenyl]-cyclohexane (TAPC) as electron donor were evaporated in vacuum in different mixing ratios (5, 50 and 95 mol%) on an ITO-coated glass substrate held at room temperature and at 110 °C. The microstructure of the C60: TAPC heterojunction was studied by grazing incidence wide angle X-ray scattering to understand the effect of substrate heating. By increasing the substrate temperature from ambient to 110 °C, it was found that no significant change was observed in the crystal size for the C60: TAPC concentrations investigated in this study. In addition to the variation done in the substrate temperature, the variation of the mole percent of the donor (TAPC) was studied to conclude the effect of both the substrate temperature and the donor concentration on the microstructure of the OSC films. Bragg peaks were attributed to C60 in the pure C60 sample and in the blend with low donor mole percentage (5%), but the C60 peaks became nondiscernible when the donor mole percentage was increased to 50% and above, showing that TAPC interrupted the formation of C60 crystals

A framework for measuring business performance in construction contracting organisations

Performance measurement has become evermore critical to business success and has been subject to a considerable amount of research and attention over the past two decades The inadequacy of traditional financially based performance measurement and the introduction of non-financial measures have been the triggers for much of this research and attention. Moreover, the Egan and Latham reports have advocated performance improvement in the construction industry, with performance measurement being a key element. Many frameworks and tools have been developed to address the recent advancements in the area. The frameworks / tools most utilised in the UK construction industry are the Key Performance Indicators (KPI), the European Foundation for Quality Management (EFQM) Excellence Model, and the Balanced Scorecard. Other frameworks have been utilised in other countries, such as the Baldrige Excellence Model in the USA, and further frameworks exist in literature. Construction companies have had to face the dilemma of choosing among the different performance measurement frameworks / tools available, or face the confusion that can be caused by using more than one simultaneously. Hence, the aim of this research is to develop a framework that measures business performance in a more comprehensive manner. The scope of the research is to focus on construction contracting organisations, as a proof of concept, with possible future modifications / generalisations to other types of construction companies. An analysis of the gaps in knowledge in business performance measurement, conducted based on the literature review, came to confirm the need for this research. A `Construction Strategy Map' was devised to measure strategic performance in the framework, based on the strategy map feature of the Balanced Scorecard but adapted for construction contracting organisations. An illustrative case study was presented to show how the Construction Strategy Map was used to develop an organisational strategy map in a major UK contracting organisation. Another tool for measuring excellence performance in the framework, the `Construction Excellence Model', was also devised, and based on the initial hybrid framework previously developed in this research. A statistical analysis was used to confirm the model that addressed the issues of reliability and validity of the questionnaire survey as a measuring instrument, evaluated the criteria and sub-criteria of the model using confidence intervals and factor analysis, and computed empirical weights of the model criteria using factor regression coefficients. The performance measurement framework in its entirety, as well as its components (the integrated methodology, the Construction Strategy Map, and the Construction Excellence Model) were validated through expert feedback. The framework was further evaluated in terms of performance measurement frameworks in business and construction management literature and the performance improvement techniques of six sigma, lean construction, knowledge management and sustainable construction, to strengthen its external validity. Finally, the conclusions, benefits and limitations of the framework, recommendations to industry and possible further work in research were discussed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The development of a comprehensive framework for measuring business performance in construction

Business performance measurement has been the subject of considerable research over the past fifteen years. Most of this research has been triggered by the inadequacy of financial indicators and the increasing use of non-financial indicators. Consequently, companies have to choose from many available frameworks / methods to monitor their business performance such as the Balanced Scorecard, Excellence Models and industry key performance indicators (KPI). The choice of one framework / method over the others might omit important performance information, and the use of more than one simultaneously can cause confusion and the use of valuable time and resources. This paper describes the PhD research underway to develop a comprehensive business performance measurement framework for construction organizations. The research adopts a hypothetico-deductive approach that comprises two main stages. First, the framework is formulated from existing well-established frameworks in literature. The second stage is the empirical testing of the framework that uses triangulated methods for collecting and analysing data. The paper further discusses the scope of the research within the industry, and finally the use of the framework in measuring business performance and its interface with the construction KPI

Theoretical formulation of a framework for measuring business performance in construction

Business performance measurement, across industries, has significantly changed over the past two decades, integrating non-financial with financial measures. Moreover, the Egan and Latham reports have advocated performance improvement in the construction industry, with performance measurement being a key element. The purpose of this paper is to theoretically formulate a framework for measuring business performance in construction. The framework builds upon the well-established principles of the Balanced Scorecard and Business Excellence models. Formulation is based on integrating the criteria / perspectives of the founding frameworks into performance factors, and integrating the underlying logic. The formulation process is evaluated by comparing the proposed framework against the Balanced Scorecard, Excellence models, Total Quality Management frameworks in literature, and to the Performance Prism. The proposed framework is further adapted for construction companies and is shown to include the Construction Best Practice Programme - Key Performance Indicators that are based on Egan's industry report

Dynamic scheduling model for the construction industry

Purpose:Basic project control through traditional methods is not sufficient to manage the majority of realtime events in most construction projects. This paper proposes a Dynamic Scheduling (DS) model that utilizes multi-objective optimization of cost, time, resources and cashflow, throughout project construction.Design/methodology/approach:Upon reviewing the topic of Dynamic Scheduling, a worldwide Internet survey with 364 respondents was conducted to define end-user requirements. The model was formulated and solution algorithms discussed. Verification was reported using predefined problem sets and a real-life case. Validation was performed via feedback from industry experts.Findings:The need for multi-objective dynamic software optimization of construction schedules and the ability to choose among a set of optimal alternatives were highlighted. Model verification through well-known test cases and a real-life project case study showed that the model successfully achieved the required dynamic functionality whether under the small solved example or under the complex case study. The model was validated for practicality, optimization of various DS schedule quality gates, ease of use, and software integration with contemporary project management practices.Practical/Social implications:Optimized real-time scheduling can provide better resources management including labour utilization and cost efficiency. Furthermore, DS contributes to optimum materials procurement, thus minimizing waste.Originality/value:The paper illustrates the importance of DS in construction, identifies the user needs, and overviews the development, verification and validation of a model that supports the generation of high quality schedules beneficial to large scale projects.</div