Zwitterionic material for construction of an antifouling polyamide thin film composite membrane

This research has been supported by the National Research Foundation (NRF) of Korea as funded by the Ministry of Education, Science and Technology (RS-2023-00241009) and by Korea Ministry of Environment (MOE) as ???Graduate School specialized in Integrated Water Resources Management???. The authors are thankful for the support

EUSO-SPB1 mission and science

The Extreme Universe Space Observatory on a Super Pressure Balloon 1 (EUSO-SPB1) was launched in 2017 April from Wanaka, New Zealand. The plan of this mission of opportunity on a NASA super pressure balloon test flight was to circle the southern hemisphere. The primary scientific goal was to make the first observations of ultra-high-energy cosmic-ray extensive air showers (EASs) by looking down on the atmosphere with an ultraviolet (UV) fluorescence telescope from suborbital altitude (33 km). After 12 days and 4 h aloft, the flight was terminated prematurely in the Pacific Ocean. Before the flight, the instrument was tested extensively in the West Desert of Utah, USA, with UV point sources and lasers. The test results indicated that the instrument had sensitivity to EASs of (sic) 3 EeV. Simulations of the telescope system, telescope on time, and realized flight trajectory predicted an observation of about 1 event assuming clear sky conditions. The effects of high clouds were estimated to reduce this value by approximately a factor of 2. A manual search and a machine-learning-based search did not find any EAS signals in these data. Here we review the EUSO-SPB1 instrument and flight and the EAS search

Interaction mechanism between low molecular weight chitosan nanofilm and functionalized surfaces in aqueous solutions

Low-molecular-weight chitosan (LMW chitosan, <10 kDa) have a significant potential for biomedical applications (e.g., antimicrobial and gene/drug delivery) because of their higher water solubility at pH values ranging from 3.0 to 8.5, compared to that of the high-molecular-weight (>100 kDa) chitosan. A comprehensive understanding of the LMW interaction mechanism with specific functional groups is necessary to predict their binding efficiency to other molecules for effectively utilizing their potential within biological systems. In this study, we used a surface forces apparatus (SFA) to investigate molecular interactions between LMW chitosan and four different functionalized self-assembled monolayers (SAMs) in aqueous solutions at pH values of 3.0, 6.5, and 8.5. Chitosan exhibited the strongest interaction energy with methyl-terminated SAM (CH3-SAM), indicating the significance of hydrophobic interaction. Many chitin/chitosan fibers in nature bind polyphenols (e.g., eumelanin) to form robust composites, which can be attributed to the strong attraction between chitosan and phenyl-SAM, presumably caused by cation????? interactions. These findings demonstrate the potential of modulating the magnitude of the interaction energy by controlling the solution pH and types of targeted functional groups to realize the optimal design of chitosan-based hybrid composites with other biomolecules or synthetic materials

A-site effects of titanate-perovskite (ATiO3)-based catalysts on dehydrogenation of N-heterocyclic molecules

Dehydrogenation reactions in liquid organic hydrogen carrier (LOHC) systems present significant challenges, particularly when aiming for low-temperature operations while ensuring that no hydrogen remains in the sub-strate molecules. Enhancing catalytic performance requires modifying the adsorption behavior of the reactants and products during dehydrogenation. Perovskites have emerged as promising catalyst supports because of their ability to modify the surface chemical properties by manipulating the cations present at the A-and B-sites. This study investigated the effects of A-site cations (Ca, Sr, and Ba) in titanate-type perovskite (ATiO3)-a proto-typical perovskite-on the dehydrogenation activity in LOHC systems. Remarkably, Pd/SrTiO3 exhibited outstanding performance by completely converting octahydro-N-methylindole to N-methylindole and releasing 5.76 wt% hydrogen over 8 h. Additionally, it dehydrogenated dodecahydro-N-ethylcarbazole to N-ethylcarbazole with a hydrogen release of 5.70 wt%. Furthermore, the catalyst demonstrated a stable performance after recy-cling tests for three times without degradation or loss of activity. The chemical state of the catalyst surface was characterized through X-ray photoelectron spectroscopy, H2-temperature programmed reduction, and chemi-sorption using NH3, CO2, and H2. The results revealed that the exceptional dehydrogenation activity of Pd/ SrTiO3 is due to the presence of suitable surface oxygen vacancies and abundant acid-base sites

Inverted fuel geometry implementation for a fast reactor: Potential improvements in neutronic and thermalhydraulic performance

This paper presents a detailed procedure for implementing the inverted fuel geometry to a fast reactor to improve its safety system and economy. The study is starting from the fuel unit cell, fuel assembly, reactor core, and burnup analysis. A proposed multivariable graph (v, Delta P, T-F(max)-D-co, V-F) introduced at the fuel unit cell level provides comprehensive thermalhydraulic and neutronic parameters in a single graph, allowing for an efficient optimization process. The fuel unit cell study reveals that the inverted fuel design has a higher fuel volume fraction and lower core pressure drop than conventional pin-typed fuel. This is beneficial for the reactor economy and enhances the reliability of the safety system. With the inverted fuel design, the primary loop can save pumping power by up to 40 % and provides an excess driving force for natural circulation. The male-female axial grid structure separating the fuel assembly potentially eliminates coolant flow path restriction and fretting issues. The core is named the Inverted Core Fast Reactor (IC-FR), an LBE-cooled fast SMR designed to generate 60 MWth for at least 40 years of full-power operation without refueling and fuel shuffling. IC-FR is a transportable reactor and has load following capability that can be deployed for many applications, including marine and land-based applications, and stand alone or mixing power grid. The burnup study of IC-FR reveals that the balance of neutron leakage and fissile inventory yields a small reactivity swing (<1$) for 40 years. This study extensively utilizes Monte Carlo (MC) code MCS for neutronic calculation. Owing to the high computational expense of MC code, the approaches to optimize the MC usage are also presented

Ultrasound standing wave spatial patterning of human umbilical vein endothelial cells for 3D micro-vascular networks formation

Generating functional and perfusable micro-vascular networks is an important goal for the fabrication of large and three-dimensional tissues. Up to now, the fabrication of micro-vascular networks is a complicated multitask involving several different factors such as time consuming, cells survival, micro-diameter vasculature and strict alignment. Here, we propose a technique combining multi-material extrusion and ultrasound standing wave forces to create a network structure of human umbilical vein endothelial cells within a mixture of calcium alginate and decellularized extracellular matrix. The functionality of the matured microvasculature networks was demonstrated through the enhancement of cell-cell adhesion, angiogenesis process, and perfusion tests with microparticles, FITC-dextran, and whole mouse blood. Moreover, animal experiments exhibited the implantability including that the pre-existing blood vessels of the host sprout towards the preformed vessels of the scaffold over time and the microvessels inside the implanted scaffold matured from empty tubular structures to functional blood-carrying microvessels in two weeks

Mapping techniques for collocation method of time-fractional convection???diffusion equations in domains with cracks

This paper proposes numerical methods that effectively deal with time-fractional convection???diffusion equations containing crack singularities. To deal with singularities, we design the geometrical mapping whose push-forward from the parameter space into the physical space generates point singularity functions based on the parametrization of the circular arc and NURBS (non-uniform rational B-spline). We adopt the collocation method with B-spline basis functions to approximate the solution in the spatial direction and enrich the approximation space by k-refinements in IGA (Isogeometric Analysis). For the discretization along the temporal direction, we employ the explicit Predictor-Corrector (PC) scheme that has the order and of the truncation error for the linear and quadratic interpolation, respectively. Taking advantage of the NURBS geometrical mapping, we demonstrate the performance of the proposed methods applying to time-fractional convection???diffusion equations with nonlinear terms on curved domains containing crack singularities

Human reliability evaluation method covering operator action timing for dynamic probabilistic safety assessment

Dynamic probabilistic safety assessment (PSA) has been introduced due to the limitations of static-based PSA such as the difficulty to analyze dynamic sequences caused by stochastic random events. While various research has been performed to achieve this integration, quantifying risk in dynamic PSA is still challenging because operator response models that can provide a branch probability according to the timing of operator action in dynamic scenarios have not yet been addressed. Existing human reliability analysis (HRA) models only consider the time given to operators for actions insofar as it can impact the failure probabilities of the human actions, despite the timing of the actions being a vital element of HRA for dynamic scenarios. This paper proposes an operator action timing-based human reliability evaluation method for dynamic PSA to evaluate the distribution of operator action timing. The method covers operator action timings with a model that convolutes two time distribution functions to provide the probability of the success or failure of an operator action. To demonstrate the practicality of the proposed method and its effectiveness, a case study and uncertainty analysis for a small break loss of coolant accident with two operator tasks were conducted

Stability of Hill's spherical vortex

We study stability of a spherical vortex introduced by M. Hill in 1894, which is an explicit solution of the three-dimensional incompressible Euler equations. The flow is axi-symmetric with no swirl, the vortex core is simply a ball sliding on the axis of symmetry with a constant speed, and the vorticity in the core is proportional to the distance from the symmetry axis. We use the variational setting introduced by A. Friedman and B. Turkington (Trans. Amer. Math. Soc., 1981), which produced a maximizer of the kinetic energy under constraints on vortex strength, impulse, and circulation. We match the set of maximizers with the Hill's vortex via the uniqueness result of C. Amick and L. Fraenkel (Arch. Rational Mech. Anal., 1986). The matching process is done by an approximation near exceptional points (so-called metrical boundary points) of the vortex core. As a consequence, the stability up to a translation is obtained by using a concentrated compactness method

Promotional effect of Mn on Pt/Al2O3 catalysts in HC, CO, and NOx oxidation for controlling diesel emission

Emissions from diesel engines, including hydrocarbons (HCs), carbon monoxide (CO), and nitric oxide (NO), cause serious environmental and human health problems. Diesel oxidation catalysts (DOCs) are drawing attention for their ability to eliminate such harmful exhausts effectively. Here, we report significantly improved activities of Pt-based catalysts, which are widely used as DOCs, in the oxidation of HC, CO, and NOx after Mn addition. Mn-doped Pt/Al2O3 showed significantly lower light-off temperatures in the oxidation of HC, CO, and NOx than those of the unmodified Pt/Al2O3 catalysts, by as much as 30 degrees C. The size of Pt particles was reduced from 71 nm to 33 nm after Mn addition, as evidenced by X-ray diffraction analysis and transmittance electron microscopy. Additionally, the interaction between CO and Pt on Mn-doped catalysts was weakened, and the CO adsorbed on Pt was readily oxidized even at room temperature, as confirmed by diffuse reflectance infrared Fourier-transform spectroscopy and CO temperature-programmed desorption experiments. The results of this study provide insights towards the improvement of the activity of Pt-based DOCs used for HC, CO, and NOx oxidation, by enhancing the fundamental understanding of the Pt nature promoted with Mn