Processing of nano-micro copper materials for the production of conductive circuits

Copper inks potentially provide a cost-effective alternative to silver for printed electronic circuits. In glass-based applications such as PV or smart glass, they can provide a means of conductivity enhancement or additional functionality. Three inks consisting of a mixture of nano and micro copper particles were systematically studied to examine the relationship between sintering temperature, sintering time and gaseous environment on the electrical qualities of the sintered printed films deposited on FTO coated glass. There is a definite interaction between the particulate nature of the ink, the sintering conditions, and the conductive properties of the film. Films containing only nano-particles provide the most conductive films with optimum sintering conditions of temperature of 225 °C for 60 minutes. The inclusion of micro particles increased the ideal sintering temperature but lowered the sintering time. An ink containing an equal mixture of nano and micro particles exhibited the lowest performance. This could be attributed to partial oxidation of the nano-particles along the conductive path, which occurs as a result of the presence of the micro particles. Other samples were photonically sintered using a PulseForge 1200 laboratory photonic sintering unit where the number of pulses, pulse power, pulse frequency and the intra pulse gap could be varied. An initial optimization study identified an operational range of photonic energy profile. The best possible line conductivity obtained using these optimum conditions was around a 1/3 of that obtained by conventional thermal sintering. This relative conductivity of photonically sintered features further deviated from conventionally sintered features as the film thickness increased and as the line width reduced. Laser / NIR techniques were found ineffective to sinter the copper ink used in this study. The possibility to manually blend copper and silver paste ink was investigated and an optimum blend of 25% silver and 75% copper could be used which had maintained conductivity, cost, and adhesion benefits

Developing capacity sharing strategy for vehicular networks with integrated use of licensed and unlicensed spectrum

A widely deployed cellular network, supported by direct connections, can offer a promising solution that supports new services with strict requirements on access availability, reliability, and end-to-end (E2E) latency. The communications between vehicles can be made using different radio interfaces: One for cellular communication (i.e., cellular communication over the cellular network based on uplink (UL)/downlink (DL) connections) and the other for direct communication (i.e., D2D-based direct communications between vehicles which allows vehicular users (V-UEs) to communicate directly with others). Common cellular systems with licensed spectrum backed by direct communication using unlicensed spectrum can ensure high quality of service requirements for new intelligent transportation systems (ITS) services, increase network capacity and reduce overall delays. However, selecting a convenient radio interface and allocating radio resources to users according to the quality of service (QoS) requirements becomes a challenge. In this regard, let’s introduce a new radio resource allocation strategy to determine when it’s appropriate to establish the communication between the vehicles over a cellular network using licensed spectrum resources or D2D-based direct connections over unlicensed spectrum sharing with Wi-Fi. The proposed strategy aims at meeting the quality of service requirements of users, including reducing the possibility of exceeding the maximum delay restrictions and enhancing network capacity utilization in order to avoid service interruption. The proposed solution is evaluated by highlighting different conditions for the considered scenario, and it is demonstrated that the proposed strategy improves network performance in terms of transmitted data rate, packet success rate, latency, and resource usag

Thermal sintering of printable copper for enhanced conductivity of FTO coated glass substrates

Copper inks potentially provide a cost effective replacement to silver for printed electronic circuits. In glass based applications such as PV or smart glass, it can provide a means of conductivity enhancement or additional functionality. Three inks consisting of a mixture of nano and micro copper particles were systematically studied to examine the relationship between sintering temperature, sintering time and gaseous environment on the electrical qualities of the sintered printed films deposited on FTO coated glass. There is a definite interaction between the particulate nature of the ink, the sintering conditions and the conductive properties of the film. Films containing only nano-particles provide the most conductive films with optimum sintering conditions of temperatures of 225 °C for 60 min. The inclusion of micro particles increased the ideal sintering temperature but lowered the sintering time. An ink containing an equal mixture of nano and micro particles exhibited the lowest performance and this could be attributed to partial oxidation of the nano-particles along the conductive path, which occurs as a result of the presence of the micro particles

Assessing the Dynamic Performance of Thermochemical Storage Materials

Thermochemical storage provides a volumetric and cost-efficient means of collecting energy from solar/waste heat in order to utilize it for space heating in another location. Equally important to the storage density, the dynamic thermal response dictates the power available which is critical to meet the varied demands of a practical space heating application. Using a laboratory scale reactor (127 cm3), an experimental study with salt in matrix (SIM) materials found that the reactor power response is primarily governed by the flow rate of moist air through the reactor and that creating salt with a higher salt fraction had minimal impact on the thermal response. The flowrate dictates the power profile of the reactor with an optimum value which balances moisture reactant delivery and reaction rate on the SIM. A mixed particle size produced the highest power (22 W) and peak thermal uplift (32 °C). A narrow particle range reduced the peak power and peak temperature as a result of lower packing densities of the SIM in the reactor. The scaled maximum power density which could be achieved is >150 kW/m3, but achieving this would require optimization of the solid–moist air interaction

Optimisation of CaCl2 impregnated expanded graphite and alginate matrices – Targeted salt loading

The incorporation of salt hydrates in thermochemical energy storage is often limited by poor kinetics and mechanical instability during charge and discharge cycles. This study explores the influence of salt loading on the energy storage capacity and charge/discharge performance of salt-impregnated expanded graphite and alginate composites. By controlling the salt bath concentration during composite synthesis, the quantity of salt within the bead can be regulated. Four composites have been synthesised with salt wt% values ranging from 63.7 to 77.2 %, resulting in salt volumetric densities form 0.22–0.52 g/cm3 and energy densities between 1052 and 1281 kJ/kg. The study found that increasing salt bath concentration above 60 % significantly decreases the porosity within the composite. This reduces moisture transfer kinetics and also fails to accommodate for salt expansion and deliquescence. Consequently, composites at near-maximum salt capacity displayed diminished discharge performance and charge efficiency. Conversely, samples below the saturation threshold exhibited greater heat output and charge efficiency, contained overhydration, and maintained structural integrity. These findings highlight the importance of carefully balancing energy storage capacity with improved reaction kinetics and stability to achieve an optimal storage solution in solar thermal systems or waste heat recovery

First trimester spontaneous rupture of an unscarred uterus in a multiparous woman: a case report

The rupture of an unscarred uterine is a rare life-threatening event that usually occurs late in pregnancy or during labor. Spontaneous uterine rupture, as in our case, is extremely uncommon and rarely diagnosed before laparotomy. Herein, we present a case of spontaneous uterine rupture in a 32 year old multiparous woman with no previous uterine surgery. The patient presented with acute abdomen at 11 weeks of gestation. Preoperative diagnosis based on clinical and ultra-sonographic findings was ruptured ectopic pregnancy. However, emergency laparotomy showed uterine rupture with extrusion of a dead fetus within intact amniotic sac in the abdomen. The defect was repaired in layers and the patient was discharged in a good condition after five days of hospital stay. Multiparity is a risk factor for spontaneous uterine rupture even in the first trimester. It should be kept in mind in any pregnant multiparous woman presenting with acute abdomen and shock. The absence of vaginal spotting and lack of history of uterine surgery give a false sense of security

Advancements and Challenges in the Use of Cold Mix Asphalt for Sustainable and Cost-Effective Pavement Solutions

Even with the high advancement of the pavement industry, the use of traditional hot mix asphalt (HMA) for pavement construction and maintenance is associated with high energy consumption, greenhouse gas emissions, and production costs. As a result, researchers and industrial practitioners aspire to use cold mix asphalt (CMA) as an alternative that offers environmental and economic benefits. This paper provides an overview of the advancements and challenges in using CMA for sustainable and cost-effective pavement solutions. The paper reviews portrays, and discloses CMA’s recent benefits, such as reduced energy consumption, lower emissions, and enhanced durability. Additionally, the paper addresses the challenges associated with using CMA, including its limited application areas and potential performance issues. It discusses the strategies being developed to overcome these challenges. Furthermore, the paper concludes with recommendations for the future of research and industry development of CMA to further promotion. Meanwhile, it is finalizing the current sight for using CMA as a sustainable, cost-effective pavement solution