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Environmentally Benign Natural Hydrogel Electrolyte Enables a Wide Operating Potential Window for Energy Storage Devices
No full textThe development of energy-efficient storage platforms is of paramount importance. Specifically, wearable, smart, flexible, and portable electronic devices with small size, lightweight, and high safety are of urgent need for several applications. To achieve these criteria, green, sustainable, nonflammable, and biodegradable hydrogel electrolytes are essential. To this end, we developed a LiCl@starch-based hydrogel via readily gelatinization of starch. The ionic conductivity of the synthesized gel was tuned via controlled variation of the LiCl content, as revealed by the electrochemical impedance spectroscopy (EIS) measurements. The developed starch gel network with 2 M LiCl showed ultrahigh ionic conductivity of 0.079 S·cm-1 with excellent thermal stability and nonflammability. The rheological characteristics are aligned with enhanced ionic conductivity. Using the commercially available activated carbon (AC), the assembled supercapacitor symmetric device (AC//2-LiCl@starch//AC) withstands a wide operating voltage window of 2.4 V with outstanding specific capacitance (62.3 F/g), energy density, and reliable self-discharge time. These findings imply that this quasi-solid biopolymer gel can be a viable electrolyte for various energy storage devices
Dissecting dietary alkylresorcinols: a compile of their distribution, biosynthesis, extraction and functional properties
No full textAlkylresorcinols (ARs) are natural bioactive ingredients produced by: bacteria, fungi, sponges, and higher plants, possessing a lipophilic polyphenol structure with a myriad of biological properties. Focusing on the importance of ARs, several analogs can be extracted from different natural resources. Interestingly, the composition of ARs is usually reflective of their source, with structural differences to exist among ARs isolated from different natural sources. The identified compounds from marine are distinguished by sulfur atom and disulfide bond, while the alkyl chain of bacterial homologs are recognized for their saturated fatty acid chains. ARs occurrence in fungi is still poorly documented however most of the isolated fungal molecules are characterized by a sugar unit attached to their alkylated side chains. The biosynthetic pathway of ARs is postulated via a type III polyketide synthase in which the fatty-acyl chain is elongated and cyclized to generate ARs. The structure-activity relationship (SAR) has gained an increasing interest to mediate for ARs biological activities as discussed herein for the first time from their different resources. ARs extraction procedures showed much progress compared to classical methods compiling organic solvents with supercritical extraction appearing as a potential technique for producing highly purified food-grade of AR homologs. The current review also presents on the rapid qualitative and quantitative determination of ARs to increase accessibility for screening cereals as potential sources of these bioactives
Automated Management of Time Extension Claims
No full textDisputes within the construction industry have caused parties to incur additional costs not accounted for. Ranking as one of the highest sources of disputes, there is a need to diminish reliance on the human factor in the extension of time (EOT) process and to bolster it with automation commodities. Six disadvantages were identified through the literature: poor record keeping, delayed event notification, an arduous process of EOT-related clauses within contracts, the lack of a superior delay analysis technique (DAT), no automation of a DAT, and finally a lack of standardized EOT submission reports. Research efforts have endeavored in tackling the drawbacks of the EOT process individually, no solution is provided to overcome all drawbacks at once to create one seamless process. This research aims to overcome the disadvantages present within the EOT submission process to provide a solution for the manual effort conducted in an EOT claim submission. Such was achieved though automated solutions that involve (1) live delay event notification and its proactive approvals; (2) natural language programming to extract EOT-related clauses; (3) a superior DAT; (4) the automation of the DAT; and (5) standardized claim document reporting system. The foregoing were then encompassed in a web-based system hereafter referred to as the automated management of time extension claims (AMTEC). AMTEC was then applied to a case study involving an EOT claim submission; it was initially applied manually and then using AMTEC. The level of effort, duration, and disputes within the entire process were compared in both scenarios. Results show that the duration for the processes decreased by 79% and the level of effort was decreased by 52%. Disputes within both scenarios were further analyzed and AMTEC was capable of overcoming the disputes faced within the manual process between parties
Asphaltene onset pressure measurement and calculation techniques: A review
No full textAsphaltene precipitation can result in several production, operational, and transportation problems during oil recovery. If asphaltene precipitates and deposits, it can reduce reservoir permeability, damage wellbore equipment, and plug the pipelines. It is therefore extremely important to evaluate the conditions at which asphaltene precipitation occurs; this is referred to as the asphaltene onset pressure. Asphaltene onset pressure has been measured using many different experimental techniques. There have also been many attempts along the years to predict asphaltene onset pressure using mathematical correlations and models. This research provides an up-to-date comprehensive review of the methods by which asphaltene onset pressure can be measured using laboratory experiments and mathematical models. The research explains the main mechanisms of all the laboratory experiments to measure asphaltene onset pressure under static conditions and how to conduct them and highlights the advantages and limitations of each method. The research also provides a summary of the commonly used mathematical models to quantify asphaltene onset pressure directly and indirectly
Towards a reconciliatory approach to ungrading in writing classes: A response to Crusan
No full textThis article provides a response to Deborah Crusan\u27s paper on ungrading and reflects on the existing potentials and challenges associated with using this concept. The article also offers a reconciliatory perspective that attempts to bring together the competing writing assessment paradigms and to take into consideration contextual limitations and opportunities
Rebalancing the Scales: A Comparative Study Between Egyptian Contract Law’s Rules on Unequal Contracts and the American Unconscionability Doctrine
Get PDFTraditionally, contracts were envisioned as pacts struck between equals. Their enforcement was considered a form of honoring the free will and autonomy of the parties. This theoretical imagination is no longer valid today; the concentration of wealth and power in the hands of some individuals or institutions means they can name their terms and force the other party between taking or leaving it. When the need to contract is pressing, the weaker party is forced to accept any imposed terms. Thus, strict enforcement of contractual terms helps the powerful further their interests at the expense of their helpless partners. Today, the law, including Egyptian law, recognizes this situation and intervenes in those unequal contracts to rebalance the scales tipped by inequality. This paper examines the Egyptian Civil Code’s general rules designed to protect weaker contractual parties and suggests reforms to enhance their functionality. It begins by exploring contracts’ source of obligatory power advocating the theory of “Equality in Exchange” which suggests that contract enforceability can only be morally grounded in the fairness of its terms. Next, it presents the relevant rules of the Civil Code and notes the mediocre results of their practical application. Then, an overview of the American doctrine of unconscionability is presented to showcase how the same issues are handled in the legal system of one of the most powerful modern economies. Finally, reforms are suggested to the Egyptian Civil Code to empower courts to protect weaker contractual parties
Degradation of the Mechanical Properties and Hydrogen Generation in Cement Under Gamma Irradiation Assessed by Atomistic Simulation
Get PDFAlthough understanding the effect of the gamma-ray on cement-based materials is essential for many applications, such as the concrete contaminate of nuclear reactors or the storage of radioactive waste in cement-based waste forms, such understanding is still not fully developed. The importance of having such an understanding is becoming of utmost importance, especially with calls to extend the lifetime of nuclear power plants, and also due to some recent incidents of failures of the concrete structure in the nuclear fields. In this work, the details of preparing three molecular models as a representative structure of the main binding phase of cement-based materials, calcium-silicate-hydrate (C-S-H) are presented. These models have different Ca/Si ratios of 1.3, 1.5, and, 1.7. For a comparison purposes, The Tobermorite 14 Å which is a crystalline analogue of C-S-H with a Ca/Si=0.83 is included in this study. In addition, a full description regarding the procedure followed to simulate the irradiation events is given here. The gamma dose simulated in the work is up to11.9 MGy, which is equivalent to the gamma dose received by concrete containment of the light water reactor over 10 years. A semi-classical force field (REAXFF) has been adopted here due to its capability to capture the chemical reactions that are anticipated to happen during irradiation (bond breakage and formation). On the other hand, a classical force field (CSHFF) has been used for the calculation of the mechanical properties as CSHFF is capable of correctly describing the mechanical response of cement hydrates. By examining the structural and mechanical properties of the C-S-H before and after irradiation, a deterioration in the mechanical properties and a formation of H2 molecules are observed. Both effects are attributed to the status of water in the interlayer space of C-S-H. For example, water dissociation causes a reduction in the ultimate compressive strength of the C-S-H. This is because the dissociated water reduces the cohesion of the C-S-H by reducing the charge of the C-S-H layers. In addition to that, water dissociation is considered the first step towards hydrogen formation as it provides the precursor to form H2 molecule. On the other hand, water evaporation is shown to have a negative correlation with the young’s modulus. This is because water exists in the interlayer space acts as a bridging solid between the C-S-H layer. Moreover, by comparing the mechanical response of the different models upon irradiation, it revealed that the C-S-H with a C/S: 1.3 ratio is more suitable to be used for the concrete containment of the nuclear power plant as its loss of only 37.5% of its compressive strength. conversely, the C-S-H model with a C/S ratio of 1.7 is shown to be more appropriate for nuclear waste confinement applications as no hydrogen production is observed during the irradiation. This is attributed to the highly defective structure of the silicate chain which provides more active sites to attract the protons and that prevent hydrogen formation. The results of this work have a very important implication in describing the origin of the degradation in cement-based materials due to radiation exposure which is the first step towards the design of cement-based materials resistant to radiation damage
Valuing Circularity: Sustainable Finance with Real Options methodology
Get PDFThis thesis presents an enhanced framework for valuing circular investments based on the Value Hill model using real options analysis. We propose a new flexible numerical methodology for valuing circularity using the Least Squares Monte Carlo simulation (LSMC) method of Longstaff and Schwartz (2001). The Value Hill model of circularity represents the course followed by the value of an asset, specifically after primary use. To validate the efficiency of our model, we conduct an empirical study on the smartphone business using the case of Apple. Results of our empirical analysis show that investing in circularity enhances financial value. Our model enables analysts, managers, and sophisticated investors to make more informed decisions when assessing such projects
Applying the structural equation model approach to study the simultaneous relationship between women’s empowerment and mental disorder in Egypt
Get PDFThin-Film Nanocomposite Membranes with Alumina Nanoparticles for Textile Wastewater Treatment Applications
No full textThin-film nanocomposite (TFN) membranes are gaining great interest in industrial wastewater treatment due to their superior performance, especially for higher water flux and pollutants’ rejection, as well as improved chemical, thermal and mechanical stabilities, compared to other types of membranes. The performance of TFN membranes can be enhanced using different types of nanofillers, among which ceramic nanomaterials, such as Al2O3, offer a promising potential for applications involving treatment of industrial wastewater such as textile effluents, and this is due to their stability, hydrophilicity, and relative low cost. The study of the TFN membrane properties and structure allows the optimization and improvement in the membrane performance. This study aims at the preparation and characterization of TFN membranes with Al2O3 nanoparticles for the treatment of textile industrial wastewater, more specifically for removing dyes and salt solutes as well as for separating dyes from salt solutes. This work prepared thin-film composite (TFC) membranes and TFN membranes on polyether sulfone (PES) support membranes prepared by phase inversion. A polyamide (PA) selective layer was then synthesized atop the PES support by interfacial polymerization using m-phenylenediamine (MPD) and trimesoyl chloride (TMC) as the PA precursors. TFN membranes incorporated different amounts of Al2O3 nanoparticles within the PA selective layer during its formation. The MPD:TMC ratio was varied in the preparation of TFC and TFN membranes and the Al2O3 nanoparticles amounts were also varied in the preparation of the TFN membranes. The prepared membranes were characterized using different techniques. Fourier Transfer Infrared (FT-IR) and X-ray Photoelectron Spectroscopy (XPS) were used to study the composition of TFC/TFN membranes and the effect of changing MPD:TMC ratio on the membrane structure and the degree of cross-linking within the PA layer. The porosity, pore structure and morphology of the membranes were investigated using Scanning Electron Microscopy (SEM) and nitrogen gas adsorption analyzed using the Brunner-Emmett-Teller (BET) theory. The hydrophilicity and surface roughness were analyzed by contact angle and Atomic Force Microscopy (AFM) measurements. The mechanical and thermal properties were assessed using Thermo Gravimetric Analysis (TGA) and tensile tests. The performance of TFC/TFN membranes were studied in terms of pure water flux, permeate flux, dye, and salt rejection rates, using single dye aqueous solutions, salt aqueous solutions, and dye/salt aqueous mixtures. The results showed that the PES support membranes exhibited drop-like macrovoids with smooth surface, confirmed by a low surface roughness of Ra 4.48 (±0.50) nm. The porosity of the support membrane indicated the predominance of mesopores of ca. 5 nm with fewer larger pores of more than 30 nm. The support membrane had a comparatively hydrophobic surface with a contact angle of 65.34o (±6.83). The effect of varying the Al2O3 nanoparticles content on the structure, properties, and performance of TFC/TFN membranes in separating dyes form salts, was investigated for an MPD:TMC ratio of 2 w/v% MPD and 0.4 w/v% TMC. Different loadings of Al2O3 nanoparticles were tested, and the results showed that the incorporation of Al2O3 changed the pore structure of the PES support membranes to wavy finger-like macrovoids. Additionally, TFN membranes exhibited larger porosity in the 3-10 nm range, higher hydrophilicity, 48.68 to 59.35o contact angles, smoother surfaces, 36.17 to 51.65 nm roughness, than the corresponding TFC membrane of ca. 5 nm mesopores, contact angle of 65.34o, and roughness of 61.32 nm. Furthermore, TFN membranes had thinner PA layers varying between 271.2 nm for the lowest Al2O3 loading (1x10-3 w/v%) to 145.1 nm for the highest Al2O3 loading (1x10-1 w/v%), as compared to 309.4 nm for the corresponding TFC membrane. Surface SEM images showed some Al2O3 aggregation in the high content TFN membrane (1x10-1 w/v%). Porosity analysis indicated larger mesopores in the range of 3-8 nm with higher number of pores of \u3e 6 nm for TFN membranes as compared with the corresponding TFC membrane. TFN membrane performance in separating dye and salt solutes from a mixture exhibited improved performance for TFN membranes as compared to the TFC membrane. For brilliant green (BG) dye/NaCl mixtures, improvement in permeate flux values ranged between 4.26 and 12.56 L/m2h for the lowest and highest Al2O3 amounts, 1x10-3 and 1x10-1 w/v%, respectively, as compared to a flux of 3.34 L/m2h for the TFC membrane. The dye/salt separation performance, measured by the selectivity factor, demonstrated higher values ranging between S = 2.77 and 9.12 for TFN membranes, which corresponds to an increase of 18.37% and 289.74% compared to the TFC membrane. Other dyes, as bromothymol blue (BTB) and reactive red (RR) salt mixtures showed the same trend as BG/NaCl with lower values for the selectivity factor ranging between S = 2.53 and 7.17 for BTB/NaCl mixtures and between S = 2.07 and 6.01 for RR/NaCl mixtures. The incorporation of Al2O3 nanoparticles improved the thermal and mechanical properties for all TFN membranes. The best performing TFN membrane was found to have Al2O3 loading of 1x10-2 w/v% (M3 membrane). This membrane had relatively larger pore width of \u3e 6 nm compared to other TFN membranes. The contact angle and surface roughness of M3 were 45.04o (±5.10) and 38.74 (±6.51) nm with a PA layer thickness of 160.4 nm. M3 hydrophilicity, larger pores, smooth surface, and thinner PA layer improved the pure water flux by ca. +150% relative to the TFC membrane. M3 exhibited the best performance for dye/salt separation with a high dye/salt selectivity factor (S) across different dye/salt mixtures, namely 9.12 (± 1.32), 7.17 (± 0.26), and 6.01 (± 0.22) for BG/NaCl, BTB/NaCl, and RR/NaCl, respectively. In determining the impact of cross-linking on membrane performance, a series of TFN membranes with a fixed amount of Al2O3 nanoparticles (1x10-2 w/v% Al2O3), and varying MPD:TMC ratios, 2:0.4 w/v% (M3 membrane), 2:0.2 w/v% (M5 membrane), and 2:0.1 w/v% (M8 membrane) were prepared. The results showed that increasing MPD:TMC ratio to 2:0.1 w/v% resulted in nearly doubling the degree of cross-linking to 0.73, from 0.39 for the MPD:TMC ratio of 2:0.4 w/v%. This was accompanied by an increase in N/O ratio to 0.83 from 0.66. The increase in the cross-linking degree resulted in less developed wavy finger-like pores in the PES support. The effect of cross-linking was more pronounced on the PA layer surface showing larger ridge and valleys features, more nanoparticle agglomeration, and higher surface roughness, increasing to 44.05 (±4.29) nm (M8 membrane), from 38.74 (±6.51) nm (M3 membrane). The higher cross-linking affected the PA layer thickness which decreased from 160.40 nm for M3 to 76.39 nm for M8, as well as the membrane porosity that showed smaller mesopores in the range of 10-20 nm for the M8 membrane with a larger number of pores at ca. 6 nm. M5 membrane with intermediate cross-linking showed a complex pore structure in the range of 3-8 nm, and no pores in the range of 10-20 nm. For membrane performance, the higher surface roughness, smaller pores, and decreased PA thickness, all associated with more cross-linking, led to a reduction in the permeate flux from 11.13 L/m2h for the M3 membrane to 3.93 L/m2h for the M8 membrane. The NaCl rejection increased from 10.96% for M3 to 70.02% for M8, which corresponds to +538.87% improvement. All TFN membranes exhibited high dye rejection rates using BG, as a representative dye in NaCl aqueous solution, as this showed the highest selectivity factor using the lowest MPD:TMC ratio of 2:0.4 w/v%. The selectivity factor followed the order of M3 (S=9.12) \u3e M5 (S=3.15) \u3e M8 (S=1.43), indicating that the M8 membrane exhibited high rejection rates for both the dye and the salt solutes. The effect of changing the content of Al2O3 nanoparticles using the higher MPD:TMC ratio of 2 w/v% MPD and 0.1 w/v% TMC, on the structure, properties, and membrane performance for dye and salt removal, was investigated. Different loadings of Al2O3 nanoparticles were tested, and the results showed that Al2O3 changed the pore structure of the support membranes to wavy finger-like macrovoids that are less developed compared to TFN membranes with lower MPD:TMC ratio (2:0.4 w/v%). In addition, TFN membranes exhibited larger porosity in the range of 3-10 nm, higher hydrophilicity with contact angle values ranging between 42.27 and 56.40o, smoother surfaces ranging between 37.91 and 68.22 nm roughness, than the corresponding TFC membrane of ca. 5 nm mesopores, a contact angle of 62.77o, and roughness of 82.23 nm. Moreover, TFN membranes had thinner PA layers varying between 120.3 nm for the lowest Al2O3 loading (1x10-3 w/v%) and 64.93 nm for the highest Al2O3 loading (1x10-1 w/v%), as compared to 152.8 nm for the corresponding TFC membrane. Surface SEM images showed some Al2O3 aggregation in the higher content TFN membrane (1x10-1 and 1x10-2 w/v%). Porosity analysis indicated larger mesopores in the range of 3-8 nm with higher number of pores of \u3e 6 nm for TFN membranes as compared to the corresponding TFC membrane. M7 membrane, with the lowest Al2O3 loading (1x10-3 w/v%), showed a complex pore structure in the range of 3-10 nm, and no pores in the range of 10-20 nm. The performance of TFN membrane in removing both dye and salt solutes from a mixture of BG, used as a representative dye in NaCl aqueous solution, showed improved performance for TFN membranes as compared to the TFC membrane. BG was selected as a representative dye as it exhibited high selectivity factor using MPD:TMC ratio of 2:0.4 w/v%. The permeate flux increased to 2.05 and 5.90 L/m2h for the lowest and highest Al2O3 amounts, 1x10-3 and 1x10-1 w/v%, respectively, compared to 1.52 L/m2h flux of TFC membrane. The efficiency of dye/salt removal, indicated by the selectivity factor, demonstrated low values ranging between S = 1.21 to 2.31 for TFN membranes, relative to S = 1.30 for TFC membrane. The best performing TFN membrane for the removal of the dye and salt solutes was found to have an Al2O3 loading of 1x10-2 w/v% (M8). This membrane had comparable porosity relative to other TFN membranes. The contact angle and surface roughness of M8 were 42.27o (±6.62) and 44.05 (±4.29) nm with a PA layer thickness of 76.39 nm. M8 hydrophilicity, larger pores, smooth surface, and thinner PA layer improved the pure water flux by ca. +50% relative to the TFC membrane. M8 membrane exhibited the best performance for efficient dye/salt removal with high dye rejection (99.96% for BG dye), and high NaCl salt rejection (70.02% from the BG/NaCl mixture), resulting in dye/salt selectivity factor (S) of 1.43 for BG/NaCl mixture