• Energy Research
• SA close
• BE close
• CM close

The heat generation from recent advanced computer chips is increasing rapidly. This creates a challenge in cooling the chips while maintaining their temperatures below the threshold values. Another challenge is that the heat generation in the chip is not uniform where some chip components generate more heat than other components. This would create a large temperature gradient across the chip, resulting in inducing thermal stresses inside the chip that may lead to a high probability to damage the chip. The locations in the chip with heat rates that correspond to high heat fluxes are known as hotspots. This research study focuses on using thermoelectric modules (TEMs) for cooling chip hotspots of different heat fluxes. When a TEM is used for cooling a chip hotspot, it is called a thermoelectric cooler (TEC), which requires electrical power. Additionally, when a TEM is used for converting a chip’s wasted heat to electrical power, it is called a thermoelectric generator (TEG). In this study, the TEMs are used for cooling the hotspots of computer chips, and a TEC is attached to the hotspot to reduce its temperature to an acceptable value. On the other hand, the other cold surfaces of the chip are attached to TEGs for harvesting electrical power from the chip’s wasted heat. Thereafter, this harvested electrical power (HEP) is then used to run the TEC attached to the hotspot. Since no external electrical power is needed for cooling the hotspot to an acceptable temperature, this technique is called a sustainable self-cooling framework (SSCF). In this paper, the operation principles of the SSCF to cool the hotspot, subjected to different operating conditions, are discussed. As well, considerations are given to investigate the effect of the TEM geometrical parameters, such as the P-/N-leg height and spacing between the legs in both operations of the TEC mode and TEG mode on the SSCF performance.

La production industrielle d'huile de palme génère simultanément une quantité substantielle de fibres de grappe de fruits vides (EFB) qui pourraient être utilisées comme matière première dans une bioraffinerie à base de lignocellulose. Les sous-produits de la lignine générés par ce processus peuvent offrir des possibilités d'isolation des produits à valeur ajoutée, tels que le p-hydroxybenzoate (pBz), pour aider à compenser les coûts d'exploitation. L'analyse de la lignine EFB par spectroscopie de résonance magnétique nucléaire (RMN) a clairement révélé la présence d'acétate lié et de pBz, la saponification révélant que 1,1 % en poids de l'EFB était du pBz ; avec une teneur en lignine de 22,7 %, 4,8 % de la lignine est du pBz qui peut être obtenu comme composant pur pour être utilisé comme charge chimique. L'analyse de la lignine EFB par RMN et dérivatisation suivie d'un clivage réducteur (DFRC) a montré que le pBz acylate sélectivement le groupe γ-hydroxyle des unités S. Cette sélectivité suggère que le pBz, de manière analogue à l'acétate dans le kénaf, le p-coumarate dans les graminées et le ferrate dans un peuplier transgénique augmenté d'une féruloyl-CoA monolignol transférase (FMT), est incorporé dans la chaîne de lignine en croissance via son conjugué monolignol γ-p-hydroxybenzoylé. L'implication de tels conjugués dans la lignification des palmiers est prouvée par l'observation de nouvelles unités couplées au β-β non résinol p-hydroxybenzoylé dans les lignines. Ensemble, les données impliquent l'existence de p-hydroxybenzoyl-CoA :monolignol transférases qui sont impliquées dans la lignification chez les différents saules (Salix spp.), peupliers et peupliers faux-trembles (Populus spp., famille des Salicacées) et palmiers (famille des Arecacées) qui ont des lignines p-hydroxybenzoylées. Même sans augmenter les niveaux par la sélection ou le génie génétique, les « déchets » actuels de l'EFB d'huile de palme devraient être en mesure de générer un flux important d'acide p-hydroxybenzoïque qui offre des opportunités pour le développement de produits à valeur ajoutée dérivés de l'industrie du palmier à huile. La producción industrial de aceite de palma genera simultáneamente una cantidad sustancial de fibras de racimo de frutas vacías (EFB) que podrían utilizarse como materia prima en una biorrefinería a base de lignocelulosa. Los subproductos de lignina generados por este proceso pueden ofrecer oportunidades para el aislamiento de productos de valor agregado, como el p-hidroxibenzoato (pBz), para ayudar a compensar los costos operativos. El análisis de la lignina EFB por espectroscopía de resonancia magnética nuclear (RMN) reveló claramente la presencia de acetato unido y pBz, y la saponificación reveló que el 1,1% en peso del EFB era pBz; con un contenido de lignina del 22,7 %, el 4,8 % de la lignina es pBz que se puede obtener como un componente puro para su uso como materia prima química. El análisis de la lignina EFB por RMN y la derivatización seguida de escisión reductora (DFRC) mostró que pBz acila selectivamente el grupo γ-hidroxilo de las unidades S. Esta selectividad sugiere que pBz, análogamente con acetato en kenaf, p-cumarato en gramíneas y ferular en un álamo transgénico aumentado con una feruloil-CoA monolignol transferasa (FMT), se incorpora a la cadena de lignina en crecimiento a través de su conjugado de monolignol γ-p-hidroxibenzoilado. La participación de dichos conjugados en la lignificación de la palma se demuestra al observar nuevas unidades no acopladas a β-β-resinol p-hidroxibenzoiladas en las ligninas. Juntos, los datos implican la existencia de p-hidroxibenzoil-CoA:monolignol transferasas que participan en la lignificación en los diversos sauces (Salix spp.), álamos y álamo temblón (Populus spp., familia Salicaceae) y palmeras (familia Arecaceae) que tienen ligninas p-hidroxibenzoiladas. Incluso sin mejorar los niveles mediante mejoramiento o ingeniería genética, los 'desechos' actuales de aceite de palma EFB deberían ser capaces de generar una corriente considerable de ácido p-hidroxibenzoico que ofrezca oportunidades para el desarrollo de productos de valor agregado derivados de la industria de la palma aceitera. The industrial production of palm oil concurrently generates a substantial amount of empty fruit bunch (EFB) fibers that could be used as a feedstock in a lignocellulose-based biorefinery. Lignin byproducts generated by this process may offer opportunities for the isolation of value-added products, such as p-hydroxybenzoate (pBz), to help offset operating costs. Analysis of the EFB lignin by nuclear magnetic resonance (NMR) spectroscopy clearly revealed the presence of bound acetate and pBz, with saponification revealing that 1.1 wt% of the EFB was pBz; with a lignin content of 22.7 %, 4.8 % of the lignin is pBz that can be obtained as a pure component for use as a chemical feedstock. Analysis of EFB lignin by NMR and derivatization followed by reductive cleavage (DFRC) showed that pBz selectively acylates the γ-hydroxyl group of S units. This selectivity suggests that pBz, analogously with acetate in kenaf, p-coumarate in grasses, and ferulate in a transgenic poplar augmented with a feruloyl-CoA monolignol transferase (FMT), is incorporated into the growing lignin chain via its γ-p-hydroxybenzoylated monolignol conjugate. Involvement of such conjugates in palm lignification is proven by the observation of novel p-hydroxybenzoylated non-resinol β–β-coupled units in the lignins. Together, the data implicate the existence of p-hydroxybenzoyl-CoA:monolignol transferases that are involved in lignification in the various willows (Salix spp.), poplars and aspen (Populus spp., family Salicaceae), and palms (family Arecaceae) that have p-hydroxybenzoylated lignins. Even without enhancing the levels by breeding or genetic engineering, current palm oil EFB 'wastes' should be able to generate a sizeable stream of p-hydroxybenzoic acid that offers opportunities for the development of value-added products derived from the oil palm industry. ينتج الإنتاج الصناعي لزيت النخيل في الوقت نفسه كمية كبيرة من ألياف مجموعة الفاكهة الفارغة (EFB) التي يمكن استخدامها كمادة وسيطة في مصفاة حيوية تعتمد على اللجينوسليلوز. قد توفر المنتجات الثانوية لليجنين الناتجة عن هذه العملية فرصًا لعزل المنتجات ذات القيمة المضافة، مثل p - hydroxybenzoate (pBz)، للمساعدة في تعويض تكاليف التشغيل. كشف تحليل اللجنين EFB بواسطة مطياف الرنين المغناطيسي النووي (NMR) بوضوح عن وجود أسيتات مرتبطة و pBz، مع كشف التصبن أن 1.1 ٪ بالوزن من EFB كان pBz ؛ مع محتوى اللجنين بنسبة 22.7 ٪، 4.8 ٪ من اللجنين عبارة عن pBz يمكن الحصول عليه كمكون نقي للاستخدام كمادة وسيطة كيميائية. أظهر تحليل اللجنين EFB بواسطة NMR والاشتقاق متبوعًا بالانقسام الاختزالي (DFRC) أن pBz يعمل بشكل انتقائي على أسيتيل مجموعة γ - hydroxyl من وحدات S. تشير هذه الانتقائية إلى أن pBz، بالتناظر مع الأسيتات في الكناف، و p - comarate في الأعشاب، و ferulate في حور معدّل وراثيًا معززًا بـ feruloyl - CoA monolignol transferase (FMT)، يتم دمجه في سلسلة اللجنين المتنامية عبر γ - p - hydroxybenzoylated monolignol conjugate. ثبت تورط مثل هذه المترافقات في ترصيع النخيل من خلال ملاحظة وحدات p - hydroxybenzoylated غير الراتينول β - β المقترنة في اللجنين. معا، تشير البيانات إلى وجود p - hydroxybenzoyl - CoA: monolignol transferases التي تشارك في تبييض في الصفصاف المختلفة (Salix spp.)، الحور والحور (Populus spp.، عائلة Salicaceae)، والنخيل (عائلة Arecaceae) التي تحتوي على p - hydroxybenzoylated lignins. حتى من دون تعزيز المستويات عن طريق التكاثر أو الهندسة الوراثية، يجب أن تكون "نفايات" زيت النخيل الحالية قادرة على توليد تيار كبير من حمض p - hydroxybenzoic الذي يوفر فرصًا لتطوير منتجات ذات قيمة مضافة مشتقة من صناعة نخيل الزيت.

During the COVID-19 pandemic, educational mobile games may play a significant role to facilitate students’ learning. Several studies have indicated that these games using mobile phones may improve students’ learning motivation and effectiveness when they are equipped with appropriate learning strategies. However, investigating the impact of learning strategies in students’ utilization of educational mobile games has received little scholarly attention during the COVID-19 pandemic. Hence, this research proposed two learning games scenarios to fill this gap. In the first scenario, students were offered an educational mobile game with a learning strategy called ‘scaffolding strategy’; while in the second scenario, the same game was offered without the strategy. To achieve this objective, an experimental design with a research model was developed to examine the role of scaffolding learning strategy in students’ use of educational mobile games. In this experimental study, 43 students from two classes participated in the two learning scenarios. The results indicate that educational mobile gaming with the scaffolding learning strategy significantly influenced students’ utilization of the mobile game. In addition, the adoption of the learning strategy significantly affected students’ perceived enjoyment, perceived usefulness, perceived ease of use, and behavioural intention to use, compared with the same game without the learning strategy. The results also indicate that the introduction of the scaffolding learning strategy into the educational mobile game will increase students’ learning effectiveness and motivation.

Abstract Emissions and efficiency of a pellet boiler (40 kW) at nominal load were compared with emissions and efficiency at reduced load, while fired with six biomass pellets. The pellets include reed canary grass ( Phalaris arundinacea ), pectin waste from citrus shells ( Citrus reticulata ), sunflower husk ( Helianthus annuus ), peat, wheat straw ( Triticum aestivum ) and wood pellets. The measurements of emissions comprised of carbon monoxide (CO), nitrogen oxides (NO x ), sulphur oxides (SO x ) and flue dust mass concentrations (using DIN plus and isokinetic sampling techniques). Emissions varied as a function of operational loads, for each type of pellets. The CO emissions were insignificant with reed canary grass (RCG), citrus pectin waste (CPW) and straw pellets at nominal load, however, at reduced load same pellets emitted 1.9, 4.0 and 7.4 times higher CO than wood pellets, respectively. Peat pellets emitted maximum CO at nominal load (4221.1 mgNm −3 , 12.6 times higher than wood pellets) however; at reduced load CO emission was insignificant. The highest NO x emissions were reported with CPW, which were 3.4 and 4.6 times higher than wood pellets at nominal load and reduced load, respectively. Dust emissions were highest with sunflower husk and lowest with RCG pellets, at both operational modes. The best performance was reported with wood pellets, followed by RCG and pectin pellets, however, wood pellets combustion emitted 1.7 and 2.0 times higher dust DIN plus than RCG at nominal and reduced loads, respectively. Not only fuel specific combustion optimization but also operational load specific optimization is essential for efficient use of agro-pellets in this type of boilers.

Globally, the empowerment of women is a critical and challenging issue. In considering the problem, the researchers sought to investigate Women’s Empowerment (WE) in the context of Saudi Arabia. In this study the researchers applied quantitative methods and collected the cross-sectional data through a questionnaire based on a random sampling technique. The study utilized 314 useable samples to conclude the investigation. Using path analysis through Analysis of Moment Structures (AMOS) version 26.0, the study underlines a positive and significant effect of Economic Empowerment (EE) and Social Empowerment (SE) on WE. On the other hand, Political Empowerment (PE) has a negative effect on WE. Moreover, Self-efficacy (SFY) and Family Support (FS) also positively and significantly affect WE. Regarding the mediating effects, SFY mediates the positive relationship of EE and SE with WE. On the contrary, SFY did not develop a positive relationship between PE and WE. Finally, FS plays a crucial mediating role in developing the association between EE, SE, PE and WE among Saudi Arabian women. This study’s findings support policymakers and planners in developing policies and strategies to boost WE significantly. Finally, through the empirical confirmation between EE, SE, PE, SFY, FS and WE in Saudi Arabia, a Middle East country, this study’s findings add further enrichment to the depth of the literature.

Alkali activated concretes have emerged as a prospective alternative to conventional concrete wherein diverse waste materials have been converted as valuable spin-offs. This paper presents a wide experimental study on the sustainability of employing waste sawdust as a fine/coarse aggregate replacement incorporating fly ash (FA) and granulated blast furnace slag (GBFS) to make high-performance cement-free lightweight concretes. Waste sawdust was replaced with aggregate at 0, 25, 50, 75, and 100 vol% incorporating alkali binder, including 70% FA and 30% GBFS. The blend was activated using a low sodium hydroxide concentration (2 M). The acoustic, thermal, and predicted engineering properties of concretes were evaluated, and the life cycle of various mixtures were calculated to investigate the sustainability of concrete. Besides this, by using the available experimental test database, an optimized Artificial Neural Network (ANN) was developed to estimate the mechanical properties of the designed alkali-activated mortar mixes depending on each sawdust volume percentage. Based on the findings, it was found that the sound absorption and reduction in thermal conductivity were enhanced with increasing sawdust contents. The compressive strengths of the specimens were found to be influenced by the sawdust content and the strength dropped from 65 to 48 MPa with the corresponding increase in the sawdust levels from 0% up to 100%. The results also showed that the emissions of carbon dioxide, energy utilization, and outlay tended to drop with an increase in the amount of sawdust and show more the lightweight concrete to be more sustainable for construction applications.