196746 research outputs found
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A review study of various High-Temperature thermodynamic cycles for multigeneration applications
No full textMultigeneration high-temperature systems are a type of energy system that use high-temperature heat sources to produce multiple forms of energy simultaneously. They offer several advantages over traditional energy systems, including higher energy efficiency, reduced greenhouse gas emissions, and lower operating costs. Power cycles are more efficient at higher temperatures. However, material and technical restrictions make operating beyond a certain temperature challenging. Multigeneration high-temperature systems are reviewed in this study. The focus is on cycles with temperatures above 550 °C from fossil fuels, solar heat, and molten salts as heat storage mediums. According to the literature, only gas turbine plants, supercritical and ultra-supercritical steam, and supercritical CO2 cycles are relevant for this temperature. Thus, these cycles are analyzed and reviewed in terms of their applications for multigeneration of power, heat, cooling, hydrogen, and freshwater. It is found that multigeneration systems based on the supercritical CO2 cycle are most efficient compared to others, while the ultra-supercritical steam cycle is still more efficient than the gas turbine cycle. Multigenerational supercritical steam cycles seldom worked, and this is a gap in the literature. A huge potential, much more than that already addressed by former studies, exists for multi-vector supply by supercritical CO2 cycles
A Review of Atomic Force Microscopy in Skin Barrier Function Assessment
No full textSkin barrier function (SBF) disorders are a class of pathologies which affect a significant portion of the world population. These disorders cause skin lesions with intense itch, impacting patients’ physical and psychological well-being, as well as their social functioning. It is in the interest of patients that their disorder be monitored closely while under treatment, in order to evaluate the effectiveness of the ongoing therapy and any potential adverse reactions. Symptom-based assessment techniques are widely used by clinicians; however, they carry some limitations. Techniques to assess skin barrier impairment are critical for understanding the nature of the disease and for helping personalize treatment. This review recalls the anatomy of the skin barrier and describes an atomic-force microscopy approach to quantitatively monitor its disorders and their response to treatment. We review a panel of studies which show that this technique is highly relevant for SBF disorder research, and we aim to motivate its adoption into clinical settings
Linear Electro-Optic Effect in 2D Ferroelectric for Electrically Tunable Metalens
No full textThe advent of 2D ferroelectrics, characterized by their spontaneous polarization states in layer-by-layer domains without the limitation of a finite size effect, brings enormous promise for applications in integrated optoelectronic devices. Comparing with semiconductor/insulator devices, ferroelectric devices show natural advantages such as non-volatility, low energy consumption and high response speed. Several 2D ferroelectric materials have been reported, however, the device implementation particularly for optoelectronic application remains largely hypothetical. Here, the linear electro-optic effect in 2D ferroelectrics is discovered and electrically tunable 2D ferroelectric metalens is demonstrated. The linear electric-field modulation of light is verified in 2D ferroelectric CuInP2S6. The in-plane phase retardation can be continuously tuned by a transverse DC electric field, yielding an effective electro-optic coefficient rc of 20.28 pm V–1. The CuInP2S6 crystal exhibits birefringence with the fast axis oriented along its (010) plane. The 2D ferroelectric Fresnel metalens shows efficacious focusing ability with an electrical modulation efficiency of the focusing exceeding 34%. The theoretical analysis uncovers the origin of the birefringence and unveil its ultralow light absorption across a wide wavelength range in this non-excitonic system. The van der Waals ferroelectrics enable room-temperature electrical modulation of light and offer the freedom of heterogeneous integration with silicon and another material system for highly compact and tunable photonics and metaoptics.</p
Innovative electroscrubbing process for biogas impurity removal
No full textA new biogas cleaning technology was tested at the Hashøj Biogas facility in Denmark. The new technology is a PtX process which consumes only electricity to clean the biogas. The process was capable of removing a wide variety of sulfur components, most notably hydrogen sulfide and mercaptans. Additionally, a variety of volatile organic compounds (VOC) such as terpenes and benzenes were removed. Overall, the process was found to remove 99.96 % of sulfur species in the biogas alongside 94.77 % of the measured VOC. With a polishing step the biogas will be ready for use either as a substitute for natural gas, or for PtX upgrading into e.g. methanol. The purity of the hydrogen produced by the setup was found to be 98.75 %. With the implementation of a small carbon filter, it could be possible to utilize the hydrogen in either fuel cells or for gas-to-liquid purposes.</p
Predicting the solubility of gases in imidazolium-based ionic liquids with SAFT-VR Mie EoS by a novel approach based on COSMO
No full textThis theoretical study presents a novel approach to predict the solubility of CO2 and CH4 in Ionic Liquids (ILs) under various pressures and temperatures using the predictive SAFT-VR-Mie equation of state combined with the COSMO calculations. This approach involves estimating the segment number, diameter, and segment energy of the ionic liquid using the molecular volume from the COSMO model. The 2B and 4C association schemes were examined for ILs. The predicting results obtained through this innovative strategy demonstrate excellent accuracy in predicting gas solubility. The average absolute relative deviation of the most optimal association scheme scenario ranges from 4.8 to 14.2% for CO2 and 5.7 to 6.4% for CH4, respectively, without the need for binary interaction parameters
Nonlinear hydrodynamics of floating offshore wind turbines: A review
No full textFloating offshore wind turbine (FOWT) is a highly sophisticated system that involves multiphysical dynamics that includes hydrodynamics, aerodynamics, structural dynamics, servo dynamics, and mooring dynamics. Hydrodynamics is one of the most critical aspects directly related to the stabilization and safety of FOWTs. As the turbine capacity keeps growing and the target depth of the water becomes deeper, the nonlinear hydrodynamic effect becomes more significant, especially under extreme conditions that occur more frequently in recent years. In this paper, theoretical challenges and state-of-the-art research progress regarding the nonlinear hydrodynamic problems related to FOWTs and their stationkeeping systems are introduced from both numerical and physical point of view. Nonlinear wave characteristics and nonlinear hydrodynamics of wave–structure interactions are addressed with different theories ranging from linear, weakly nonlinear to fully nonlinear. A number of nonlinear phenomenon such as low-frequency resonance, transient impacts, hydroelastic coupling, current effects and shallow water effect are discussed. Theoretical inconsistency due to large horizontal motions and challenges in accounting for the viscous drag loads in the state-of-the-art engineering tools are addressed. Future perspectives are finally brought up
<i>Lactococcus </i>cell envelope proteases enable lactococcal growth in minimal growth media supplemented with high molecular weight proteins of plant and animal origin
No full textLactic acid bacteria (LAB) have evolved into fastidious microorganisms that require amino acids from environmental sources. Some LAB have cell envelope proteases (CEPs) that drive the proteolysis of high molecular weight proteins like casein in milk. CEP activity is typically studied using casein as the predominant substrate, even though CEPs can hydrolyze other protein sources. Plant protein hydrolysis by LAB has rarely been connected to the activity of specific CEPs. This study aims to show the activity of individual CEPs using LAB growth in a minimal growth medium supplemented with high molecular weight casein or potato proteins. Using Lactococcus cremoris MG1363 as isogenic background to express CEPs, we demonstrate that CEP activity is directly related to growth in the protein-supplemented minimal growth media. Proteolysis is analyzed based on the amino acid release, allowing a comparison of CEP activities and analysis of amino acid utilization by L. cremoris MG1363. This approach provides a basis to analyze CEP activity on plant-based protein substrates as casein alternatives and to compare activity of CEP homologs
Reducing Ice Adhesion to Polyelectrolyte Surfaces by Counterion-Mediated Nonfrozen Hydration Water
No full textHydrophilic anti-icing coatings can be energy-effective passive solutions for combating ice accretion and reducing ice adhesion. However, their underlying mechanisms of action remain inferential and are ill-defined from a molecular perspective. Here, we systematically investigate the influence of the counterion identity on the shear ice adhesion strength to cationic polymer coatings having quaternary alkyl ammonium moieties as chargeable groups. Temperature-dependent molecular information on the hydrated polymer films is obtained using total internal reflection (TIR) Raman spectroscopy, complemented with differential scanning calorimetry (DSC) and ellipsometry. Ice adhesion measurements show a pronounced counterion-specific behavior with a sharp increase in adhesion at temperatures that depend on the anion identity, following the order Cl- < F- < SCN- < Br- < I-. Linked to the freezing of hydration water, the specific ordering results from differences in ion pairing and the amount of water present within the polymer film. Moreover, similar effects can be promoted by varying the cross-linking density in the coating while keeping the anion identity fixed. These findings shed new light on low ice adhesion mechanisms and may inspire novel approaches for improved anti-icing coatings.</p
Synchronous mode-locking of solid-state lasers by difference frequency generation
No full textThis Letter introduces a novel, to the best of our knowledge, method for achieving mode-locking and synchronization of mode-locked output pulses from two lasers. The proposed technique leverages parametric gain from difference frequency generation. Specifically, a Nd:YAG laser is mode-locked by single-pass mode-locked pulses from a mode-locked Ti:sapphire laser using an intracavity nonlinear crystal. When the continuous-wave laser is not actively pumped, the system functions as a synchronously pumped optical parametric oscillator. This novel approach has the potential to enable new devices, especially for pump-probe applications or for generation of mode-locked pulses in spectral regions where conventional mode-locked devices are typically not available
Understanding Stimulation of Conjugal Gene Transfer by Nonantibiotic Compounds: How Far Are We?
No full textA myriad of nonantibiotic compounds is released into the environment, some of which may contribute to the dissemination of antimicrobial resistance by stimulating conjugation. Here, we analyzed a collection of studies to (i) identify patterns of transfer stimulation across groups and concentrations of chemicals, (ii) evaluate the strength of evidence for the proposed mechanisms behind conjugal stimulation, and (iii) examine the plausibility of alternative mechanisms. We show that stimulatory nonantibiotic compounds act at concentrations from 1/1000 to 1/10 of the minimal inhibitory concentration for the donor strain but that stimulation is always modest (less than 8-fold). The main proposed mechanisms for stimulation via the reactive oxygen species/SOS cascade and/or an increase in cell membrane permeability are not unequivocally supported by the literature. However, we identify the reactive oxygen species/SOS cascade as the most likely mechanism. This remains to be confirmed by firm molecular evidence. Such evidence and more standardized and high-throughput conjugation assays are needed to create technologies and solutions to limit the stimulation of conjugal gene transfer and contribute to mitigating global antibiotic resistance