Search

This paper investigates the thermal stability of metakaolin/fly ash (MK/FA) based geopolymers at elevated temperature of 500℃ and 800℃. The thermal stability of geopolymers is evaluated from the following aspects: apparent morphology, residual compressive strength, volumetric shrinkage, and microstructure. The results show that the incorporation of FA contributes to the reduction of specimen cracking while the increasing of equivalent Na2O leads to severe cracking. After experiencing 800°C, the compressive strength of all specimens remains above 70 % of that at room temperature, and the specimen with high equivalent Na2O exhibits higher compressive strength. The XRD and FTIR results indicate that the chemical component of most specimens remains stable at elevated temperatures without decomposition and formation of new crystalline phases. However, the MK/FA based geopolymer exhibit considerable volume shrinkage at elevated temperatures. The shrinkage ranges from 3.2 % to 4.9 % at 500°C and 5.1–14.2 % at 800°C for different specimens. The increase of equivalent Na2O from 8 % to 16 % results in a 174.8 % increase of shrinkage. Overall, MK/FA based geopolymers exhibit convincing thermal performance, and the specimens exhibit higher residual compressive strength and chemical stability after exposure to elevated temperatures.

Maintaining quality in construction projects is paramount to project success, achieved through techniques such as Total Quality Management (TQM). However, the key factors of TQM implementation in the construction industry of developing countries are not well explored. Accordingly, this paper evaluated the causative relationship and intricacies of TQM implementation in the construction sector of developing countries. A total of 28 key factors of TQM were captured through a literature review. Thereafter, 12 significant key factors were shortlisted. Lack of top management commitment, poor customer/client satisfaction, inadequate quality of education regarding TQM, and ineffective organizational quality culture emerged as impediments to implementing TQM in the construction sector. A Causal Loop Diagram (CLD) was developed to represent interrelations between the 12 shortlisted factors. In addition, a system dynamics model (SDM) was developed. The simulation results of the developed SDM indicated an increase in TQM implementation over the period under the defined system.

Cotton is a major cash crop and backbone of the textile industry in Pakistan which is badly affected by sucking insects. Drought is an important abiotic factor in trichome development. The objective of the study was to determine the effects of drought on trichome density and length. Trichome density was measured in two ways, one through the scaling method and the other through counting the trichome density manually. The scaling method is qualitative grading while quantitative grading includes trichomecount in a card of optimized length. Three scales were finalized to classify leaves on the basis of trichomes which were counted in a specific area (0.25cm2) on abaxial side of the leaf. In drought stress, trichomes density and length were measured and compared to that in normal conditions. Trichome density varies from 12 to 56 in 0.25cm2 under drought stress. On the basis of correlation of trichome density with stomatal conductance, photosynthetic rate, PAR and transpiration ratio under drought and normal conditions, it was concluded that trichome density increased as a result of drought stress.

Kanamycin is a widely used selection agent in dicot-plant genetic transformation systems. In monocots, however, it does not seem to be effective as it has no or minimal effect on the normal growth of non-transformed plants. Kanamycin was previously demonstrated to bleach the pigments of the non-transgenic plants. This may yield the idea that kanamycin can be used as an effective screening marker rather than a selectable marker in monocots. Copyright (c) 2021 Malik Nawaz Shuja, Hasan Riaz, Muhsin Jamal, Muhammad Imran

Ultraviolet radiation, oxidation, temperature, moisture, and traffic loads produce degradation and brittleness in the asphalt pavement. Microcracks develop into macrocracks, which eventually lead to pavement failure. Although asphalt has an inherent capacity for self-healing, it is constricted. As a result, damages build beyond the ability of asphalt to repair themselves. This research employs the in-situ crack healing method of encapsulated rejuvenator technology to enhance the insufficient self-healing capability of roads. This allows the extrinsically induced healing in asphalt to assist it in recovering from damage sustained during service life. Optical microscopy, thermogravimetric analysis, and the compressive load test of capsules were done to characterise their properties. We measured the self-healing behaviour of encapsulated rejuvenator-induced asphalt utilising the three-point bending beam tests on unaged, short-term aged and long-term aged asphalt beams. The rate of oil release before and after healing was quantified using Fourier transform infrared spectroscopy. The results of these tests were utilised to explain the link between healing time, temperature, asphalt ageing, and healing level. Overall, it was determined that the encapsulated rejuvenator was acceptable for mending asphalt mixes because it increased healing temperature and duration, resulting in an up to 80% healing index.

Purpose: To analyze differences in union, complication rates and cost from surgical fixation of distal fibula fractures with fibular plating implants. Methods: In total, 380 adult patients from 2012 to 2015 treated with 12 fibular plates from 4 different manufacturers utilized by 9 surgeons were retrospectively reviewed. They were stratified into a conventional one-third tubular fibular plate group, pre-contoured anatomic locking plate group, or a heterogeneous group including 3.5-mm reconstruction, one-third tubular locking, composite, and limited compression plates. The outcomes included failure of fixation, deep infection requiring debridement, time to union, anatomic reduction, superficial infection, hardware removal, and post-traumatic arthritis. Plate and screw costs were calculated from hospital billing records. Results: Pre-contoured locking plates were used in older, female patients with a greater number of comorbidities. Open injuries and OTA 44B fractures were more likely to be an indication for pre-contoured plates. There was no difference noted in time to union between the different plating groups. Risk factors for deep infection requiring debridement included a history of tobacco use, open fractures, and pre-contoured locking plates relative to the conventional plating group. The pre-contoured plating group was on average $586 more expensive compared to the conventional group. Conclusion: Pre-contoured locking plates achieved similar radiographic outcomes compared to conventional plates with an increased risk of complications and higher cost. Surgeons should consider their choice of implant based on the patient's fracture pattern, underlying comorbidities, and risk for infection. [ABSTRACT FROM AUTHOR]

The enrichment of natural gas with hydrogen has been identified as a promising pathway for power-to-gas technology with the potential to reduce emissions while achieving feasible return on investment. The evolving regulatory market in the province of Ontario motivates the analysis of business cases for hydrogen on the industrial microgrid scale. This paper aims to investigate the financial and environmental returns associated with producing and storing electrolytic hydrogen for injection into the natural gas feed of a manufacturer’s combined heat and power plants (CHPs). A mathematical methodology was developed for investigating the optimal operation of the integrated system (power-to-gas along with the current system) by considering hydrogen-enriched natural gas. The result of this simulation is an operation plan that delivers optimal economics and an estimate of greenhouse gas emissions. The simulation was implemented across an entire year for each combination of generation price limit and storage coefficient. Because the provincial grid imposes a lesser carbon footprint than that of a pure natural gas turbine, any offset of natural gas by hydrogen reduces the carbon intensity of the system. From an environmental perspective, the amount of carbon abated by the model fell within a range of 3000 ton CO2/year. From a policy perspective, this suggests that a minimum feasible carbon price of $60/ton CO2e must be set by applicable regulatory bodies. Lastly, a Failure Modes and Effects Analysis was performed for the proposed system to validate the safety of the design.

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1478-1913.2007.00190.x Byline: Riaz Hassan (1) Author Affiliation: (1)Flinders University Adelaide, Australia