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Nanoparticle concentration and solvent exchange via organic solvent ultrafiltration
No full text<p>Downstream processing of nanoparticles after synthesis frequently involves purification, concentration and solvent exchange steps. While these are typically done via centrifugation in lab scale, ultrafiltration is a practical and economical alternative in large scale continuous production. Treating suspensions in organic solvents via ultrafiltration requires solvent-stable membranes and in this study we present the performance of cellulose ultrafiltration membranes in the concentration and solvent exchange of hydrophilic and hydrophobized silica nanoparticles using isopropanol, water, dimethyl formamide and ethanol as solvents. Hydrophobized particles formed less permeable cake layers than hydrophilic particles during concentration. All fouling was reversible upon ultrasonication while physical cleaning via stirring could only recover the complete membrane permeance fouled with hydrophilic particles in dimethyl formamide and hydrophobic particles in isopropanol and water. Quality of nanoparticle recovery was assessed by the amount recovered in retentate and cleaning suspensions as well as the particle size after these steps. Highest recovery of hydrophilic particles was obtained in dimethyl formamide and that of hydrophobic particles in isopropanol. No agglomeration of recovered hydrophilic particles was observed, while hydrophobic particles recovered via physical cleaning partly agglomerated in isopropanol and dimethyl formamide. Finally, continuous solvent exchange from isopropanol to ethanol, water and dimethyl formamide was achieved with no performance loss throughout the process.</p>
Assessing analysis of a small-scale dual rotor counter-rotation wind turbine with a unique pitch mechanism: Experimental parametric study
No full text<p>The increasing global energy demand and the search for sustainable solutions have brought wind energy to an important position among renewable energy sources. This study focuses on the design, manufacturing and testing of a double rotor counter-rotating wind turbine aiming to improve aerodynamic efficiency and structural integrity. The NREL S822 airfoil optimised for low wind speeds is used. In the study conducted under laboratory conditions using an open-circuit wind tunnel, an alternator with a direct drive system was used to minimize mechanical losses and maintenance requirements. The double rotor system, which operates in counter rotation, has shown high performance especially at low wind speeds. The results show that the blades do not rotate contrarily when the torque difference between the two rotors is greater than 28.46%. The maximum power output was obtained when the front blade angle was 12 degrees and the rear blade angle was 3 degrees. Compared to the single rotor wind turbine, the power output of the twin rotor wind turbine is 60% higher. With the increase in the front blade angle, the power output of the twin rotor wind turbines decreased. In addition, the experimental results were statistically analysed and a mathematical model was created to predict the power output of double rotor wind turbines.</p>
Design and manufacture of hybrid mesh for hernia treatment
No full text<p>The warp knitting method is typically used to create hernia mesh. It can add new qualities to the meshes due to the formation of micro/nanofibers, cell proliferation, biocompatibility, non-adhesion, and drug release properties. Within the purview of this work, warp-knitted mesh (polypropylene) with micro/nanofibers was created. On this constructed mesh structure, silk fibroin/polyurethane/levan/curcumin fibers were produced using the centrifugal jet spinning technique. When SEM images were examined, the average fiber diameter was 932 +/- 407 nm, and the pore diameter was 20 mu m. The nanofiber warp-knitted fabric was measured to have a bursting strength of 182.9 +/- 11 kPa. It was determined that the abdominal wall's predicted elasticity value of 15.65% horizontally was enough for both men and women. It was determined that the hybrid mesh structure performed better against E.coli bacteria and that the curcumin-infused mesh had an antibacterial effect. It was found that meshes might be employed as hybrid meshes for the treatment of hernias.</p>
Synergistic hybrid nanostructures for Ultra-Sensitive photoelectrochemical detection of hepatocellular carcinoma ctDNA
No full text<p>In recent years, the integration of quantum dots (QDs) and upconverting nanoparticles (UCNPs) has emerged as a promising strategy in biomedical research, leveraging QDs' efficient down-conversion and UCNPs' remarkable up-conversion capabilities. This synergy has attracted significant attention for its potential in biomedical applications, particularly in sensitive detection systems. Here, we report the development of a highly sensitive photoelectrochemical (PEC) employing a hybrid nanostructure comprising CdSe QDs and NaYF4:Yb,Er UCNPs. This sensor was specifically tailored for the detection of circulating tumor DNA (ctDNA) with mutations associated with hepatocellular carcinoma (HCC) using synthetic DNA probes. The CdSe QDs and NaYF4:Yb,Er UCNPs were synthesized and integrated using Triton X-100, a non-ionic surfactant. Comprehensive characterization confirmed the successful formation of the hybrid nanostructure, crucial for optimizing sensor performance. Our PEC platform effectively addressed the challenge of detecting single-nucleotide mismatches in HCC ctDNAs, demonstrating superior sensitivity compared to conventional electrochemical methods. Notably, the system exhibited excellent linearity across a broad concentration range (400 aM to 200 pM), surpassing traditional electrochemical approaches. Key to its clinical relevance, the PEC sensor achieved a remarkable limit of detection (2.32 aM) and limit of quantification (15.61 aM), underscoring its potential for early-stage cancer diagnosis as well as very good recovery from spiked samples. This capability is pivotal in overcoming current diagnostic limitations, such as the asymptomatic nature of early-stage HCC and the need for more accurate biomarkers. Our study highlights the promising role of hybrid nanostructures in enhancing biosensor sensitivity and response times, offering a pathway towards improved early detection and management of HCC.</p>
Fabrication of superhydrophobic sorbent material via<i> in</i><i>-situ</i> coating of melamine sponge with halloysite nanotube and fluoroalkylsilane using supercritical CO2 coating system for efficient oily water treatment
No full text<p>This study presents the preparation of a novel sorbent material with high performance and special wettability for oily water treatment, utilizing halloysite nanotube (HNT) and perfluorooctyl triethoxysilane (PFOTES). Fluoroalkyl silanes, such as PFOTES, offer significant advantages over other monomers and alkoxysilanes due to their superior water-repellent properties and high solubility in CO2 atmosphere, enabling homogeneous polymerization and coating. The modification of PFOTES with HNT was successfully achieved in the supercritical CO2 (scCO2) environment at 35 degrees C and 125 bar using a sol-gel technique. Subsequently, HNT-modified PFOTES nanoparticles were coated onto melamine sponge (MS) via a drainage technique, marking the first application of this method to create a superhydrophobic (WCA: 165.2 degrees) and superoleophilic (OCA: 0 degrees) sorbent material (MSPFOTES). The MS-PFOTES sorbent material, produced via a one-step, two-pot coating method, demonstrated exceptional sorption capacities ranging from 39.1 to 117.5 g/g for oily pollutants / organic solvents. Additionally, MS-PFOTES achieved an outstanding separation efficiency of 99.99 % for diesel-water mixtures in continuous separation processes. The fabricated material also exhibited remarkable thermal stability, chemical resistance, and robustness. Experimental findings obtained in this study highlight the significant potential of this innovative coating technique for the direct preparation of sorbent material with special wettability for oily water treatment.</p>
Extrinsic and intrinsic factors for electrochemical reduction of carbon dioxide on heterogeneous metal electrocatalysts
No full text<p>Excessive CO2 emissions from the traditional consumption of fossil fuels have led to severe environmental and ecological issues, including global temperature rise, atmospheric carbon imbalance, and expansion of desertification. To address these challenges, various green technologies and remediation techniques aimed at reducing CO2 emissions are being implemented worldwide. Among them, the electrochemical reduction (ECR) of CO2 into value-added fuels and chemicals has emerged as a promising strategy to complete the anthropogenic carbon cycle and promote sustainable development. However, the ECR of CO2 faces several challenges, including the inherent properties of CO2, harsh reduction conditions, poor catalytic performance, limited catalyst efficiency and stability, intermediate properties, competitive side reactions, and low product selectivity. Addressing these challenges requires a comprehensive understanding of both the extrinsic and intrinsic factors that influence the reduction process. This review provides a detailed examination of these factors, along with insights into the reduction principles and reaction mechanisms for the ECR of CO2. Extrinsic factors include the reduction temperature, electrolyte type and concentration, reaction cell design, catalyst/mass loading, electrolyte pH, pressure, and applied potential. Intrinsic factors encompass the active site properties of electrocatalysts, binding strength between CO2 and the reduction intermediates on the catalyst surface, electroactive surface area, nanocatalyst dimension, surface structure, morphology, and composition of the electrocatalyst. Additionally, we discuss advanced influences, such as electric fields, surface strain, dangling bonds, structural defects, ionomers, and hydrophobicity of electrocatalysts. The role and impact of each factor are analyzed, with a particular focus on the stability, reduction efficiency, and selectivity of the electrocatalyst and the product distribution in the ECR of CO2. This review aims to provide valuable insights for advancing the design and optimization of efficient and selective electrocatalysts to effectively address global CO2 emissions.</p>
New database of sustainable solid particle materials to perform a material-based design for a thermal energy storage in concentrating solar power
No full text<p>Renewable energies have surged worldwide, aiming to mitigate greenhouse gas emissions and reduce dependence on fossil fuels. Concentrated solar power (CSP) with thermal energy storage (TES) emerges as a viable alternative to bridge the gap between renewable energy generation and consumption. However, existing CSP plants face a significant challenge in optimizing performance due to the operational temperature limitations of solar salt. While alternative materials, such as solid particles for sensible heat storage in solar towers exceeding 600 degrees C, have been proposed, the crucial aspect revolves around selecting a new alternative sustainable low-cost material for use as a TES media. This article investigates the optimization of CSP-TES systems by evaluating alternative sustainable low-cost materials sourced from several sectors such as the mining or metallurgical industry, municipal solid wastes, or demolition wastes. The materials, either used in their original form or formulated into aggregates for mortars, underwent thorough a property comparison focused on thermal, physical properties, and cost. With this data, a database was created using the Constructor software from ANSYS and integrated with the Selector software from the same company that provides instrumental for the creation of a comprehensive repository of sustainable materials, providing a database that serves as a practical reference guide for optimizing the selection of sustainable materials as TES in CSP plants. Then, a baseline could be established for selecting a sustainable material for a specific design, considering the properties of the materials. This methodology consists of redesigning and adapting the system according to the material, and it is known as the Materials-Based Design (MBD) process.</p>
The role of the Ministry of Foreign Affairs in military operations in Cyprus: a bureaucratic politics approach
No full text<p>This study examines the emergence of a bureaucratic group which specialized on Cyprus, and explores the impact that this group had on decisionmaking tied to the Cyprus Question, from 1954, when Cyprus became an international issue, to 1974, with the onset of military operations on the island. Drawing on the Cyprus Military Operations as a case study, a bureaucratic-policy approach is adopted to shed light on the place of bureaucratic institutions in the foreign policy decision-making mechanism.</p>
Colorless distributed combustion effects on hydrogen-enriched methane fuels combustion in a laboratory-scale combustor
No full text<p>This research explores the burning of methane fuel enriched with hydrogen in a distributed mode within a laboratory-scale combustor. The objective is to improve the combustion efficiency of these fuels by incorporating hydrogen enrichment. However, it is evident that hydrogen enrichment increases flame temperature. Therefore, the application of colorless distributed combustion (CDC), an advanced combustion technique that controls flame temperature by slowing down reaction rates, is proposed to achieve ultralow emissions and a uniform temperature with an expanded combustion flame. To achieve this goal, a Computational Fluid Dynamics (CFD) code was employed to model hydrogen-enriched methane fuels. The findings suggest that the introduction of hydrogen enrichment raises flame combustion temperatures from around 1625 K to 1654 K when up to 20 % H2 is present in the fuel. This temperature elevation correlates with a rise in the anticipated levels of NOX within the combustion chamber. As the oxygen percentage decreases, the flame expands, and flame temperatures, for instance, for fuel containing 20% H2, decrease from around 1654 K to 1359 K at 15% O2. Consequently, NOX levels in the combustion chamber drop from approximately 565 ppm to values below 0,98 ppm. The distributed regime demonstrates the capability to mitigate the increases in temperature and emission levels associated with hydrogen, thereby suggesting that hydrogen-enriched gas turbines could operate within broader flammability limits.</p>
A presentation for the semigroup of order-preserving full contraction mappings of a finite chain
No full text<p>For n is an element of Z+ , let Xn={1,& mldr;,n} be a finite chain and Tn be the full transformation semigroup on Xn . If OCTn is the set of all order-preserving and full contraction mappings on Xn , then it is well-known that OCTn is a submonoid of Tn . In this paper we give a monoid presentation of OCTn .</p>