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Mesoporous Hollow Nested Nanospheres of Ni, Cu, Co-Based Mixed Sulfides for Electrocatalytic Oxygen Reduction and Evolution
No full textNanostructured thiospinel-based transition metal sulfides with high-density active sites hold great application potentials as non-noble electrocatalysts. In this paper, high-performance bifunctional oxygen electrocatalysts of well-designed Ni, Cu, Co-based mixed sulfides, which combine two highly active thiospinels of NiCu2S4 and CuCo2S4, have been prepared successfully through solvother mal reaction, calcination, and the following sulfurization. The products of Ni, Cu, Co-based mixed sulfides present unique hollow structures with mesopores, in which several nano particles-assembled hollow nanospheres of 30-50 nm in thickness are nested one by one, forming multishell morphologies. Benefiting from the synergistic effect of combining NiCu2S4 and CuCo2S4 and the well-designed hollow structures with large electroactive surfaces/interfaces and efficient mass transportation, the obtained Ni, Cu, and Co-based mixed sulfides exhibit remarkable electrocatalytic activities and excellent long-term durability toward not only oxygen reduction reaction (ORR) but also oxygen evolution reaction (OER). Regarding the overall oxygen-based electrocatalytic performance, the mixed sulfides present an extremely low potential difference (0.73 V) between the ORR and OER in KOH electrolyte, delivering significant superiority to their oxide counterparts and the commercial catalyst of Pt/C, as well as most of the oxygen bicatalysts reported recently. Therefore, the obtained Ni, Cu, and Co-based mixed sulfides hold great promise as low-cost bifunctional catalysts with high efficiency for oxygen-based advanced energy storage systems
Extraction of Cellulose from Paper Towels for Sustainable Bio-Based Polyurethane Adhesives.
No full textThe increasing consumption of paper towels generates significant waste, necessitating sustainable recycling solutions. This study investigates the extraction of cellulose from wastepaper towels and its application in bio-based polyurethane adhesives. The extraction process includes alkali treatment, bleaching, and acid hydrolysis to obtain recycled cellulose (rCL). The extracted cellulose is then used in polyurethane (PU) synthesis alongside castor oil polyol (COP) and methylene diphenyl diisocyanate (MDI), with performance compared to industrial cellulose-based polyurethane. The obtained rCL and synthesized PU adhesives have been characterized with FT-IR spectra for structural confirmation. In addition, the synthesized PU adhesives demonstrated improved mechanical and thermal properties. At room temperature, tensile testing showed that rCL-5wt.% exhibited a higher tensile strength of 7.37 MPa as compared to 6.36 MPa for CL-5 wt.%, indicating better mechanical strength of PU adhesives with rCL. Differential scanning calorimetry (DSC) analysis showed an elevated glass transition temperature (Tg) of 82.24℃ for the rCL-5wt.% and 72.26 oC for the CL-5wt.% as compared to 68.74 oC for the control sample, indicating improved thermal stability. Gel swell analysis confirmed a lower swelling and higher gel content for rCL-5wt.% as compared to CL-5wt.%, reflecting a denser, more robust polymer network structure with high crosslinking with rCL. These results suggest that recycled cellulose is a viable alternative to industrial cellulose for sustainable polymer applications. The study contributes to eco-friendly material development by promoting waste utilization and reducing reliance on petrochemical-based adhesives
To study electron density of the ionosphere
No full textThe method contains observations of the Electron Density of the lonosphere, Solar activities, etc. In addition, we took out some cases of earthquakes from 01-01-2023 to 20-06-2030 for further studies. The Earthquakes: (1) Machala, South America (2.783°S,79.852°W), 6.8 M on 18-03-23, (2) Afghanistan (36.523°N, 70.943°E), 6.5 M on 21-03-23, (3) Papua New Guinea (4.323°S, 143.166°E), 7.0 M on 02-04-23, (4) Panama (7.567°N, 82.335°W), 6.3 M on 05-04-23, (5) Mexico (49.215°N, 129.618°W), 6.0 M on 13- 04-23, (6) New Zealand (29.958°S, 177.831°W), 7.1 M on 24-04-23, (7) Tonga, Fiji (15.628°S, 174.493°W), 7.6. M on 10-05-23, (8) Canillá (15.107°N, 90.805°W), 6.4 M on 18-05-23, (9) Loyalty Island (23.206°S, 17.742°E), 7.7 M on 19-05-23, (10) Japan (35.524°N, 140.522°N), 6.1 M on 26-05-23. For Prediction, we will observe the data of Electron Density which we will get from the GPS, and it will show signs around 1-9 days before the Earthquake. We can consider the observed sign of earthquakes only if the value of other activities is low or negligible. Other activities like dust storms, radioactive pollution, volcanic eruptions, thunderstorms, etc., can also affect the ionosphere\u27s layers, which erase the signs of earthquakes
College Attendance: The Great Depression and Effects of the New Deal.
No full textThis article examines the effects of the Dust Bowl on college attendance amid the Great Depression. The objective is to track college attendance in the Midwest during The Great Depression and determine whether the various work and education programs introduced by President Franklin Roosevelt had a positive impact on continued collegiate enrollment. The New Deal enacted by F.D.R. brought the passage of banking reform laws, work and agricultural programs, and emergency relief programs. FDR\u27s second part of the New Deal established new agencies to address the lack of economic opportunity, Official agencies like the Civilian Conservation Core, Works Progress Administration, and implementation of social security. These programs brought dramatic changes to the workforce and still attendance rates, following an initial dip after 1929, remained steady at Kansas State Teachers College. This study shows that economic depression and recession did not have an overwhelming effect on college attendance even during one of the greatest man-made agricultural disasters in modern history
Crafting Better Meal Ordering Experiences: The Pizza PittStop Case
No full textThe following is about Pizza PittStop, which is a food ordering application concept to improve meal ordering. The project is driven by user-centricity, aiming to gain maximum convenience, efficiency, and general customer satisfaction, The process is started with intensive interviews of customers to identify their needs and issues, and followed by designing an empathy map to gain better insight into users\u27 perceptions. Then, we built personas of customers summarizing different needs and issues of target market. For identifying where to improve, user stories and user journey maps were crafted, recording key touchpoints where ordering of meals could be optimized. Problem statements were written to summarize hypotheses about where and how to improve in order to ultimately form a clear value proposition and goal statement for the application. A competitive audit was also conducted, analyzing strengths and weaknesses of meal delivery services to inform Pizza PitStop\u27s development of features. The process of design involved brainstorming and iterating concepts in sketches, user flows, and Figma wireframes. The concepts were critiqued to ensure they were serving users and providing a cohesive experience from start to finish to end. The aim of this research is to demonstrate how iterated design and user-based research can significantly influence meal ordering to make it inclusive, user-friendly, and responsive to modern diners
High-Capacity Calcium Vanadate Composite with Long-Term Cyclability as a Cathode Material for Aqueous Zinc-lon Batteries
No full textRechargeable aqueous zinc (Zn)-ion batteries (AZiBs) have been emerging as a complementary technology to lithium-ion batteries in energy storage applications sowing to their safe operation, low cost, and eco-friendly features. However, the development of AZiBs for commercialization is still in its infancy and is hindered by the unstable cathode. Herein, a calcium vanadate/vanadium oxide (CaV3O7/V2O3) composite (treated as CaVO) was prepared by a facile solvothermal synthesis and investigated as a cathode material for AZiBs. As a result, the CaVO composite cathode exhibited a high reversible capacity of 321.8 mAh/gover 300 cycles at 1 A/g and maintained a reversible capacity of 268 mAh/g over 600 cycles at 2A/g. Interestingly, the CaVO composite cathode showed excellent operating stability over 3000 cycles, even at a high current rate of 10A/g. The assembled Zn/CaVO battery delivered outstanding energy densities of 329 and 315 Whk/g at power densities of 206 and 414 Wk/g, respectively. In addition, an insight into the energy storage mechanism in Zn/CaVO composite rechargeable aqueous batteries was systematically elucidated using structural and morphological analyses. The CaVO composite cathode serves as an excellent Zn2+ host owing to the presence of Ca-ion pillaring, which results in good reversibility and excellent rate performance
Dual Metal-Loaded Porous Carbon Materials Derived from Silk Fibroin as Bifunctional Electrocatalysts for Hydrogen Evolution Reaction and Oxygen Evolution Reaction
No full textDeveloping electrocatalysts with high efficiency and long-term stability for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is significant to massively generate hydrogen energy by water splitting. In this work, cobalt and tungsten dual metal-loaded N-doped porous carbon electrocatalysts derived from silk fibroin were successfully prepared through facile carbonization and chemical activation by KCl and applied as efficient electrocatalysts for HER and OER. After chemical activation, the resulting catalysts present a unique hierarchical porous structure with micro-, meso-, and macropores, which can expose more implantation sites for catalytic active metals and will in turn promote the efficient diffusion of the electrolyte. The catalyst under the optimized condition (CoW@ACSF) has a specific area of 326.01 m2 /g. The overpotential at a current density of 10 mA/cm2 of CoW@ACSF is 138.42 ± 10.39 mV toward HER and 492.05 ± 19.04 mV toward OER. Furthermore, the overpotential only increases 101.2 mV toward HER and 66.00 mV toward OER after the long-term stability test of chronopotentiometric test over 10 h, which confirms the excellent stability of the CoW@ACSF, owing to its unique carbon shell structure. This work gives an insight into the design and engineering of silk fibroin-derived carbon materials for electrocatalysis toward HER and OER
Universal Strategy of Bimetal Heterostructures as Superior Bifunctional Catalysts for Electrochemical Water Splitting
No full textUtilizing earth-abundant metals to design economical and efficient electrocatalysts for cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) is critical for acquiring clean hydrogen energy by the electrochemical overall water-splitting system. In this work, we reported a facile and universal strategy toward developing a suite of bimetallic heterostructures, representing as highly efficient catalysts of the HER/OER process. By hybridizing transition-metal sulfides (CoS2, NiS2, FeS2, and CuS) with highly active MoS2 nanosheets, all heterostructural catalysts achieved largely improved bifunctional activity originating from the special interfacial interaction as well as synergetic catalytic effects. As a result, the optimal CoS2@MoS2/CC and NiS2@MoS2/CC heterostructures displayed the lowest overpotentials at 10 mA/cm2 , which only required 31 and 225 mV for HER/OER, respectively. After assembling for water splitting, the electrolyzer exhibited a very small cell voltage of 1.58 V to reach 10 mA/cm2 . This result is better than a lot of reported non-precious metal catalysts. Our strategy experimentally confirms the feasibility of the heterostructure to enhance the bifunctional performance of advanced electrocatalysts for electrochemical water splitting
Catechol Containing Polyhydroxy urethanes as High-Performance Coatings and Adhesives
No full textGreen routes for the synthesis of high-performance isocyanate-free polyurethane coatings and adhesives are intensively searched for. In this article, we report a solvent- and isocyanate-free formulation for novel poly(hydroxy urethane) glues bearing strongly adherent catechol groups. These adhesives are prepared by the polyaddition of a CO2 sourced tricyclic carbonate, hexamethylene diamine, and a catecholamine (dopamine). The role of the catechol functions on the PHU curing and on the final PHU properties are investigated. Although the dopamine slows down the curing of the formulation, this catecholamine added at only 3.9 mol % impressively improves the mechanical and adhesion performances of PHU. The lap shear adhesion of our product surpasses those of PHU that do not contain the catechols. We also demonstrate that the catechol-bearing PHU glues are competing with the adhesion performances of commercial PU glues, at least when a thermal curing is implemented to overcome the low reactivity of cyclic carbonate with amines. The use of renewable feedstocks, the solvent-free process, the atom economy polyaddition reaction, and the absence of any toxic reagent benefit the sustainability of the final product
Sustainable Epoxy Vitrimers from Epoxidized Soybean Oil and Vanillin
No full textEpoxidized soybean oil (ESO)-derived epoxy thermosets often suffer from poor mechanical properties and lack of reprocessability. This study presents a sustainable epoxy vitrimer synthesized by curing ESO with vanillin-derived Schiff base (VSB) as a dynamic hardener and 1,2-dimethylimidazole as an accelerator. The phenolic hydroxyl groups in VSB exhibit high reactivity with ESO\u27s epoxy groups, with a curing activation energy of 108.9 kJ/mol. By adjusting the feed ratio of ESO and VSB, the vitrimer\u27s mechanical properties can be tailored from soft to tough and hard materials. The dynamic Schiff base bonds impart the vitrimer with excellent reprocessability, weldability, reconfigurability, and programmability, facilitating recycling and reshaping of cured materials. The vitrimers also exhibit superior thermal stability with an onset decomposition temperature of around 400C. This study highlights the potential of ESO-derived epoxy vitrimers as viable alternatives to traditional epoxy thermosets, offering sustainability, tunable mechanical properties, and enhanced functionality