Impact of the scattering physics on the power factor of complex thermoelectric materials

We assess the impact of the scattering physics assumptions on the thermoelectric properties of five Co-based p-type half-Heusler alloys by considering full energy-dependent scattering times vs the commonly employed constant scattering time. For this, we employ density functional theory band structures and a full numerical scheme that uses Fermi's golden rule to extract the momentum relaxation times of each state at every energy, momentum, and band. We consider electron-phonon scattering (acoustic and optical), as well as ionized impurity scattering, and evaluate the qualitative and quantitative differences in the power factors of the materials compared to the case where the constant scattering time is employed. We show that the thermoelectric power factors extracted from the two different methods differ in terms of (i) their ranking between materials, (ii) the carrier density where the peak power factor appears, and (iii) their trends with temperature. We further show that the constant relaxation time approximation smoothens out the richness in the band structure features, thus limiting the possibilities of exploring this richness for material design and optimization. These details are more properly captured under full energy/momentum-dependent scattering time considerations. Finally, by mapping the conductivities extracted within the two schemes, we provide appropriate density-dependent constant relaxation times that could be employed as a fast first-order approximation for extracting charge transport properties in the half-Heuslers we consider

Urea-Hydroxyapatite Nanohybrids for Slow Release of Nitrogen

While slow release of chemicals has been widely applied for drug delivery, little work has been done on using this general nanotechnology-based principle for delivering nutrients to crops. In developing countries, the cost of fertilizers can be significant and is often the limiting factor for food supply. Thus, it is important to develop technologies that minimize the cost of fertilizers through efficient and targeted delivery. Urea is a rich source of nitrogen and therefore a commonly used fertilizer. We focus our work on the synthesis of environmentally benign nanoparticles carrying urea as the crop nutrient that can be released in a programmed manner for use as a nanofertilizer. In this study, the high solubility of urea molecules has been reduced by incorporating it into a matrix of hydroxyapatite nanoparticles. Hydroxyapatite nanoparticles have been selected due to their excellent biocompatibility while acting as a rich phosphorus source. In addition, the high surface area offered by nanoparticles allows binding of a large amount of urea molecules. The method reported here is simple and scalable, allowing the synthesis of a urea-modified hydroxyapatite nanohybrid as fertilizer having a ratio of urea to hydroxyapatite of 6:1 by weight. Specifically, a nanohybrid suspension was synthesized by $\textit{in situ}$ coating of hydroxyapatite with urea at the nanoscale. In addition to the stabilization imparted due to the high surface area to volume ratio of the nanoparticles, supplementary stabilization leading to high loading of urea was provided by flash drying the suspension to obtain a solid nanohybrid. This nanohybrid with a nitrogen weight of 40% provides a platform for its slow release. Its potential application in agriculture to maintain yield and reduce the amount of urea used is demonstrated.Authors thank Hayleys Agro Ltd., Sri Lanka for initiating this research programme at SLINTEC and Nagarjuna Fertilizer and Chemical Ltd (NFCL), India for providing further support. Authors acknowledge Mr Sunanda Gunesekara of SLINTEC for assistance with scaling up the production process to enable the field trials. ARK acknowledges the financial support received from ICTPELETTRA Users Program, Trieste, Italy to conduct photoemission experiments at Materials Science beam line (MSB) and ELETTRA SRS on HA and urea coated HA samples. ARK further acknowledges Dr. R.G. Acres of MSB beam line for his extensive support to conduct photoemission experiments. We acknowledge the Department of Agriculture and Rice Research and Development Institute of Sri Lanka, in particular Dr Priyantha Weerasinghe, Mr D Sirisena and Dr Amitha Benthota for the assistance in carrying out pot and farmers filed trials. NFCL and Central Salt & Marine Chemicals Research Institute, Gujarat, India for TEM and BET analysis

Factors Influencing Online Education during COVID-19 Pandemic: Sri Lankan Students’ Perspective

This study examines the factors influencing online education for selected Sri Lankan universities during the COVID-19 pandemic. It also analyses the moderate effect of gender and type of the university on online education. Primary data were collected using a questionnaire via google form from Management students in Sri Lankan selected universities. Data analysis was done through structural equations using analysis of moment structures (AMOS) version 22.0. Attitude, internet and related facilities, curriculum, and self-motivation were found to have a significant positive impact on online education, while workload & time have no significant effect on online education. Among four factors, the strongest influence was derived from self-motivation followed by the curriculum. We have not found significant differences among male and female students’ views on online education, while the impact from the type of university is different among the two categories. This study effectively guides policy makers and university administrators across the educational institutes to decide on continuing online education. It reveals some insights to the teachers, students, and parents to understand the significance of the modern online learning environment and its positive impact on the new learning mode. There is no study related to the factors associated with the impact of online education during the Covid-19 pandemic in the Sri Lankan context

Customer Satisfaction and Revisit Intention towards Fast Food Restaurants in Sri Lanka

This study aimed at examining factors that effect of food taste, food quality, service quality, perceived price, responsiveness, restaurant environment on customer satisfaction and revisit intention. Data were collected through a structured questionnaire survey of fast food restaurant customers in a selected metropolitan area from Colombo district and students from University of Sri Jayewardenepura. The data were analyzed using SPSS 21.0 and R Studio 3.5.1 software. The study has found that food quality and perceived price are the important antecedents of restaurant customer satisfaction. Further, the results clearly showed a significant role of customer satisfaction on revisit intention and crucial impact of perceived price on customer satisfaction. In addition, revisit intention towards the fast food restaurant is directly influenced by food tastes. This study collected data from two selected groups; students from University of Sri Jayewardenepura and one metropolitan area, and data has analyzed further based on demographic characteristics further to confirm the results.  Therefore, this study provides valuable insight to restaurant managers on attracting, retaining and satisfying their customers

Undergraduate Student’s Perspectives on E-learning during COVID-19 Outbreak in Sri Lankan Universities

As education moves e-learning all over the world due to COIVD-19 pandemic, students spend more time on e-learning than ever before. This is also equally applied to the Sri Lankan education system. Thus this study examines the undergraduate students’ perspectives on e-learning during the COVID-19 outbreak in universities in Sri Lanka. Primary data was obtained from undergraduate students in Sri Lankan university using a structured questionnaire via Google form. The perspectives on e-learning education during the COVID-19 pandemic was investigated using descriptive statistics and frequency analysis. The majority of the undergraduate students felt that the e-learning version of education saved travel time and cost of accommodation. Furthermore, the study revealed that the majority of students were happy with the e-learning form of education during the pandemic since it allowed them to finish their degrees faster and access the labor market without a delay. The biggest challenges with e-learning, according to the student responses, were internet access, device availability, visionary issues, technical issues, and stress. As a result of this COVID -19 pandemic, if higher education officials in Sri Lankan universities want to keep e-learning education on going, they must focus on offering cost-effective, high-speed data connections while minimizing technological hurdles. At the same time, it is important to update and revise the curriculum content according to this new mode of education since this is a completely new situation for all. There is relatively little research on students’ perspectives on e-learning education during the COVID-19 pandemic in the Sri Lankan context and it will provide some important highlights to the researchers, parent and academics as well

IMPLEMENTATION OF GENERAL PROVISIONS ON OCCUPATIONAL HEALTH AND SAFETY IN THE FACTORY ORDINANCE (NO. 45 OF 1942) (A QUALITATIVE STUDY)

 In the late 1970s, Free Trade Zones were established in Sri Lanka as an important part of the economic development of the island. These zones were specially designated manufacturing areas which were set up to attract foreign investments to the country. In these places, occupational health and safety are vital features of the Human Resource Management. In the Sri Lankan context, studies regarding occupational health and safety are scarce. The general objective of this study was to explore the implementation of general provisions on occupational health, and safety in the Factory Ordinance (No. 45 of 1942) among workers in Katunayake Export Processing Zone. A qualitative approach was adapted to this study. The study consisted of two phases: in the first phase focus group discussion with workers were done, and in the second phase, ten in-depth interviews were conducted. Purposive sampling method was used to select participants from workers based on the inclusion criteria. Twenty workers (n=20) were selected from different factories in the zone. Saturation method was used as the guiding method of data collection. Data was analyzed using framework analysis. Study found that, implementation of general provisions on occupational health is remaining in a satisfactory level; implementing general provisions of occupational safety in work place is remaining at better status; however implementation of few provisions should be improved. A longitudinal study on occupational health and safety among factory workers and factory managers need to be conducted. In addition to that, improving awareness on Factories’ Ordinance (No. 45 of 1942) is recommended. Employers should also be empowered to intervene with managers for implementing general provisions and special provisions of occupational health and safety in the Factories’ Ordinance

Building a sustainable future: a concept paper on unleashing the potential of the bio-economy in Sri Lanka

The more comprehensive goal of this concept paper is to argue for the creation of a bioeconomy as a novel development model towards a sustainable Sri Lankan economy focusing on its emerging nature as well as its vulnerability to challenges like environmental degradation, resource depletion and economic vulnerability. A bioeconomy involves the reorganization of the resource base with a focus on biological assets and the utilization of plants, animals and microorganisms for their generation of food, materials and energy in a sustainable manner. The strategic location of Sri Lanka as a country with extensive agricultural land, diverse bio-diversity, and the need for economically sustainable and equitable growth. Therefore, this paper formulates a conceptual framework that can be used to build a bioeconomy structure in Sri Lanka with main sectors such as agriculture, energy and biotechnology. This concept paper seeks to outline a coherent strategy on how to overcome these challenges and it is proposed that the solutions should be informed by the collaborative effort of government, the private sector, academia and the communities. Thus, this paper identifies the key components and implications of a bioeconomy for Sri Lanka and seeks to contribute to further theoretical analysis, policy debate as well as practical implementation plans for developments that are both economically prosperous and environmentally benign. This work advances knowledge of bio economies in emerging nations and provides practical guidance for Sri Lanka’s bioeconomic growth

Formation of random singlets in the nanocrystalline quasi-one-dimensional spin-1/2 antiferromagnet Sr21Bi8Cu2(CO3)2O41

Induced by quenched disorder, random-singlet states occur in a variety of low-dimensional spin-1/2 antiferromagnets, some of them candidates for quantum spin liquids. Here we report measurements of the specific heat, magnetization, and magnetic susceptibility of nanocrystalline Sr21Bi8Cu2(CO3)2O41, a quasi-one-dimensional spin-1/2 antiferromagnet with alternating bonds. The results uncover the predominant presence of random-singlet spin pairs in this material, with a logarithmic probability distribution, P(J), of the renormalized, emergent exchange interaction, J, in zero magnetic field and P(J) proportional to 1/J in magnetic fields. We postulate that these unexpected J dependences, in contrast to the usual P(J) \propto 1/$J^\gamma$ with 0 < $\gamma$ < 1, and possibly also the dichotomy, arise from the finite size of the nanocrystals. Scaling functions for the specific heat and magnetization reproduce our magnetocaloric-effect data, with no adjustable parameters