Transparent glasses obtained by unconventional sintering

openGlasses are conventional manufactured by melting natural sand or silicon compounds at high temperatures. The traditional melting method requires high energy input to reach the melting temperature of precursors. Conventional solid-state sintering of powders is a valid alternative to reduce the processing temperature; however it requires time consuming thermal treatment to obtain densification. With the aim of reducing the environmental impact, energy, temperature and cost, the thesis project carried out in collaboration with the University of Lyon 1 aims to develop new ways of producing glass by employing unconventional sintering approaches. During the experimental work, three different strategies are explored: synthesis of nanoparticles at a low glass transition temperature, cold sintering process on commercial sub-micrometer particles borosilicate glass, the Spark Plasma sintering process on nanostructured silica nanoparticles. - Synthesis of nanoparticles with a low glass transition temperature: using a modifying Stober synthesis, including tetraethyl orthosilicate, as silicon precursor, and boron, calcium and sodium salts or alkoxides as precursors of modifier oxides, capable of lowering the glass transition temperature. Several parameters were investigated such as the type of precursor, the molar ratio of the oxide precursors to TEOS, the concentration of the solution and the calcination temperature. The results showed that particles with a diameter of about 150 nm were obtained, with a strong presence of organic residue. The glass transition temperature was about 950°C, likely due to the lack of successful incorporation of modifier oxides into the silica network. - Cold Sintering Process: a basic sodium hydroxide solution was selected as a liquid phase to promote densification at low temperatures. The main parameters investigated were the following: temperature, pressure, liquid/solid molar ratio and residence time of the powder in the mould. Density measurements by means of the Archimedes test and pycnometer revealed the following best parameter combinations: Pressure P=300MPa, temperature T=250°C, % liquid/mass =40, residence time t in the mould = 30 min; Pressure P=300MPa, temperature T=200°C, % liquid/mass =20, dwell time t in the mould = 120 min, The lack of an unit value of relative density is an indication of sintering having only partially taken place, which is confirmed by the high porosity visible through SEM characterisation analysis, and the lack of transparency. - Spark Plasma Sintering: the silicon oxide particles pre-treated at 900°C (in order to remove water and carbonate groups absorbed) were subjected to the sintering process by Spark Plasma. During the operations, the pressure and dwell time values were chosen and kept fixed (2GPa and 3 minutes respectively), allowing the effect of the key parameter of temperature to be assessed. Characterisation of the samples produced, carried out using SEM and Raman spectroscopy, revealed the following: * Crystallization occurs at 2GPa for temperature above 1000°C * Densification and transparency occur for a temperature of 800°C. In-situ measurements of the process combined with Archimedes density test show, however, that the sintering process is not complete. *An initial sintering step takes place at temperatures around 500°C; one could develop the idea of future experiments by decreasing the temperature, so as to decrease the energy consumption required to achieve densification. This thesis work shows that it is indeed possible to produce transparent glass using unconventional sintering techniques. From these preliminary investigations, it's possibile to confirm an important role of the particles dimension for the obtainment of dense and transparent glass components.Glasses are conventional manufactured by melting natural sand or silicon compounds at high temperatures. The traditional melting method requires high energy input to reach the melting temperature of precursors. Conventional solid-state sintering of powders is a valid alternative to reduce the processing temperature; however it requires time consuming thermal treatment to obtain densification. With the aim of reducing the environmental impact, energy, temperature and cost, the thesis project carried out in collaboration with the University of Lyon 1 aims to develop new ways of producing glass by employing unconventional sintering approaches. During the experimental work, three different strategies are explored: synthesis of nanoparticles at a low glass transition temperature, cold sintering process on commercial sub-micrometer particles borosilicate glass, the Spark Plasma sintering process on nanostructured silica nanoparticles. - Synthesis of nanoparticles with a low glass transition temperature: using a modifying Stober synthesis, including tetraethyl orthosilicate, as silicon precursor, and boron, calcium and sodium salts or alkoxides as precursors of modifier oxides, capable of lowering the glass transition temperature. Several parameters were investigated such as the type of precursor, the molar ratio of the oxide precursors to TEOS, the concentration of the solution and the calcination temperature. The results showed that particles with a diameter of about 150 nm were obtained, with a strong presence of organic residue. The glass transition temperature was about 950°C, likely due to the lack of successful incorporation of modifier oxides into the silica network. - Cold Sintering Process: a basic sodium hydroxide solution was selected as a liquid phase to promote densification at low temperatures. The main parameters investigated were the following: temperature, pressure, liquid/solid molar ratio and residence time of the powder in the mould. Density measurements by means of the Archimedes test and pycnometer revealed the following best parameter combinations: Pressure P=300MPa, temperature T=250°C, % liquid/mass =40, residence time t in the mould = 30 min; Pressure P=300MPa, temperature T=200°C, % liquid/mass =20, dwell time t in the mould = 120 min, The lack of an unit value of relative density is an indication of sintering having only partially taken place, which is confirmed by the high porosity visible through SEM characterisation analysis, and the lack of transparency. - Spark Plasma Sintering: the silicon oxide particles pre-treated at 900°C (in order to remove water and carbonate groups absorbed) were subjected to the sintering process by Spark Plasma. During the operations, the pressure and dwell time values were chosen and kept fixed (2GPa and 3 minutes respectively), allowing the effect of the key parameter of temperature to be assessed. Characterisation of the samples produced, carried out using SEM and Raman spectroscopy, revealed the following: * Crystallization occurs at 2GPa for temperature above 1000°C * Densification and transparency occur for a temperature of 800°C. In-situ measurements of the process combined with Archimedes density test show, however, that the sintering process is not complete. *An initial sintering step takes place at temperatures around 500°C; one could develop the idea of future experiments by decreasing the temperature, so as to decrease the energy consumption required to achieve densification. This thesis work shows that it is indeed possible to produce transparent glass using unconventional sintering techniques. From these preliminary investigations, it's possibile to confirm an important role of the particles dimension for the obtainment of dense and transparent glass components

Effective Water Use Efficiency Improvement Strategies

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Stakeholders’ Model in Israeli School

The authors of this paper present a stakeholder model for presenting an Israeli school from the point of view of its stakeholder, especially pupils, teachers, principals and parents. They strive to find solution to teenagers at risk in the Arab sector of Israel

The effects of media on the level of accountability of public organization

One of the features of democratic political systems is the accountability against their own performances. Media, one of the powerful elements of civil society and effectual on public thought, plays an important role in making the government responsive. To achieve this goal, the present study tries to investigate the effect of media on the improvement of the accountability level of the government agencies. The statistical society of this research includes all male students of Azad Ghaemshahr University where 320 students were selected through purposive sampling method based on Kerjesy and Morgan table. Applied research method is used in this survey. A researcher-made questionnaire was used to collect the required data. In order to validate the instrument, appropriate questions related to each variable were extracted from valid sources and finally approved by authorities. In order to calculate the reliability of the questionnaire, Cronbach’s alpha was calculated to be 89. Since the distribution of the data was normal, parametric statistical tests were used to testify the hypotheses. The findings of the study show that the media could be effective in terms of making public organizations responsive, through leading and training the public, unifying demands, and monitoring and broadcasting. However, the findings reveal that if the media were free and independent, they would better perform their responsibilities. Finally, the study at hand concludes that in comparison to other media, television is much more powerful in terms of pushing the public sector to be responsive

PENGARUH KOMPETENSI, KOMITMEN ORGANISASI, PARTISIPASI MASYARAKAT, DAN SISTEM PENGENDALIAN INTERNAL TERHADAP AKUNTABILITAS PENGELOLAAN DANA KAMPUNG DIKOTA JAYAPURA

The objective of this paper is to empirically test the determinants of accountability of village fund management in Jayapura municipality. The factors comprise of the competence of village officials, organizational commitment, community participation and internal control system.This research is a quantitative study using a survey method. Primary data were collected using a questionnaire distributed to village officials and community respondents in 14 villages in Jayapura municipality. The village apparatus consists of the Head, Secretary, Treasurer, Head of Affairs, village boards, and the communities. The analysis tool used is Warp PLS 6.0.The research results showed that the competence of village officials, community participation and the internal control system have significant effects on the accountability of village fund management. Organizational Commitment variable has no significant effect. The contribution of this research is that the competence of village officials, community participation and a good internal control system can increase the accountability of village fund management in Jayapura municipality. The government needs to intervene taking the form of assistance activities related to the determinants of this accountability, so that the management of village funds can be improved at Jayapura municipality

PENGARUH KARAKTERISTIK TUJUAN ANGGARAN DAN PENGELOLAAN KEUANGAN DAERAH TERHADAP KINERJA PEMERINTAH DAERAH STUDI PADA SKPD PEMERINTAH KOTA JAYAPURA

This study aims to analyze the Effect of Characteristics of Budget Objectives and Regional Financial Management on the Performance of Local Governments in Jayapura City in order to realize good governance, and to know the factors that influence the Performance of Local Government. The data collection technique used in this study was primarily by using a questionnaire through the surveymethod for Civil Servants (PNS), namely the head of the section and sub-section in the 28 Regional Government Work Unit (SKPD) of the Jayapura City Government. The sampling technique uses purposive sampling. Data analysis in this study used multiple linear regression analysis. The results of this study indicate that the characteristics ofthe Budget Objective: there is no influence between budgetary participation on the performance of local governments, there is a positive and significant influence between the clarity of budget objectives on local government performance, there is no influence between budget feedback on local government performance, there is no influence between evaluation of the budget for the performance of local governments, there is no influence between the difficulty of budget objectives on the performance of local governments, there is a positive and significant influence on regional financial management on the performance of local government

THE ROLE OF BURNOUT ON REDUCING EMPLOYEES' PERFORMANCE IN SOCIAL SECURITY ORGANIZATION IN TEHRAN PROVINCE

Abstract. In this research, we are looking for an appropriate answer to the question of whether job burnout can be considered as a factor in reducing job performance for employees. The purpose of this study was to measure burnout components and to investigate its relationship with employees' performance components in Social Security Organization in Tehran Province. This research is a descriptive-survey method. Using a suitable sampling method, a sample of 200 individuals was selected. The collected data were analyzed using correlation test. The results show that in general, job burnout has a significant effect on reducing employees' performance. Performance factors that affect burnout are: ability level, level of perception, motivation, evaluation, performance, perceived environmental fitness; also, various components of burnout, including emotional exhaustion, isolation and individual failure, also affect the performance of employees. Of course, the effect of burnout on perceived organizational components and credibilitywas not confirmed.Keywords: Job Burnout, Job Performance, Social Security Organization in Tehran Province

DETERMINAN AKUNTABILITAS PENGELOLAAN DANA BANTUAN OPERASIONAL SEKOLAH DI KOTA JAYAPURA

The objective of this study is to analyses the determinants of the financial management accountability of school operational fund (BOS hereafter) in Jayapura municipality, Papua province. The research method used was a survey with questionnaires. Quantitative analysis using the SPSS analysis tool was used to analyze the data collected in order to test empirically the factors that influence accountability of the management of BOS funds in beneficiary schools in Jayapura City. The results showed that the BOS funds received in Jayapura Municipality in 2019 and 2020 amounted to 24.9 billion which were managed in 14 junior high schools and 54 elementary schools. BOS spending consists of personnel spending, goods and services spending, and capital spending. Data collected from 242 respondents showed that the factors of Transparency, HR Quality, Organizational Commitment, Internal Control System had an effect on the Accountability of BOS funds. The results of the research are to provide empirical factors on the accountable management of BOS funds so that they become technical knowledge for other districts/cities in Papua Province and others in managing their BOS Fund and other public transfer funds

Spilt milk: an unusual cause of bilateral chylothorax

We report a case of bilateral chylothorax without evidence of chylous fistula in a 62-year-old man following total laryngectomy and bilateral selective neck dissection for laryngeal cancer. Chylous fistulae, a well-known complication of neck dissection, occurs following 1% to 2% of these surgeries. On rare occasions, the chyle leak may communicate with the pleural space, resulting in chylothorax. This is a rare but potentially life-threatening complication. Bilateral chylothorax following neck dissection is even rarer, with less than 25 cases reported in the literature. Early diagnosis is essential to prevent complications. Physicians should have a high index of suspicion, especially when the postoperative effusions do not respond to diuretics. Though no evidence-based treatment guidelines exist, expert opinion recommends conservative management as first-line therapy. Our patient was effectively treated by conservative management. We postulate a mechanism whereby bilateral chylothorax occurred in our patient without a chylous fistula