Monolithic Structure Research Articles

Compact structures for single-beam magneto-optical trapping of ytterbium.

At present, the best optical lattice clocks are based on the spectroscopy of trapped alkaline-earth-like atoms such as ytterbium and strontium. The development of mobile or even space-borne clocks necessitates concepts for the compact laser-cooling and trapping of these atoms with reduced laser requirements. Here, we present two compact and robust achromatic mirror structures for single-beam magneto-optical trapping of alkaline-earth-like atoms using two widely separated optical cooling frequencies. We have compared the trapping and cooling performance of a monolithic aluminum structure that generates a conventional trap geometry to a quasi-planar platform based on a periodic mirror structure for different isotopes of Yb. Compared to prior work with strontium in non-conventional traps, where only bosons were trapped on a narrow line transition, we demonstrate two-stage cooling and trapping of a fermionic alkaline-earth-like isotope in a single-beam quasi-planar structure.

Bond Strength Assessment of Normal Strength Concrete-Ultra-High-Performance Fiber Reinforced Concrete Using Repeated Drop-Weight Impact Test: Experimental and Machine Learning Technique.

Ultra-high-performance concrete (UHPC) has been used in building joints due to its increased strength, crack resistance, and durability, serving as a repair material. However, efficient repair depends on whether the interfacial substrate can provide adequate bond strength under various loading scenarios. The objective of this study is to investigate the bonding behavior of composite U-shaped normal strength concrete-ultra-high-performance fiber reinforced concrete (NSC-UHPFRC) specimens using multiple drop-weight impact testing techniques. The composite interface was treated using grooving (Gst), natural fracture (Nst), and smoothing (Sst) techniques. Ensemble machine learning (ML) algorithms comprising XGBoost and CatBoost, support vector machine (SVM), and generalized linear machine (GLM) were employed to train and test the simulation dataset to forecast the impact failure strength (N2) composite U-shaped NSC-UHPFRC specimen. The results indicate that the reference NSC samples had the highest impact strength and surface treatment played a substantial role in ensuring the adequate bond strength of NSC-UHPFRC. NSC-UHPFRC-Nst can provide sufficient bond strength at the interface, resulting in a monolithic structure that can resist repeated drop-weight impact loads. NSC-UHPFRC-Sst and NSC-UHPFRC-Gst exhibit significant reductions in impact strength properties. The ensemble ML correctly predicts the failure strength of the NSC-UHPFRC composite. The XGBoost ensemble model gave coefficient of determination (R2) values of approximately 0.99 and 0.9643 at the training and testing stages. The highest predictions were obtained using the GLM model, with an R2 value of 0.9805 at the testing stage.

Power-saving effect and sensor characteristics of sandwich structure on oxygen sensors using hot spot

A hot spot which is a glowing orange local area appears in REBa2Cu3Oy (RE: rare earth) ceramic rods when a voltage higher than a certain value is applied at room temperature. After the hot spot appears, the oxygen partial pressure in the ambient atmosphere changes the current through the rod, which can be used as an oxygen sensor without the need for a heating system. In this study, the authors investigated the oxygen-sensing characteristics and the power-saving effect of the sandwich structure in which the sensor layer was stacked between insulation layers. The sample rods were prepared by the solid-state reaction at 960 °C. Materials of 5 mol% Nd2BaCuO5-added Nd1.4Ba1.6Cu3Oy and 20 mol% Nd1.4Ba1.6Cu3Oy-added Nd2BaCuO5 were used for the sensor layer and the insulation layer, respectively. The sensitivity to the oxygen increased with increasing voltage applied to the rod. Under the condition where 17.8 V was applied to the rod with the sandwich structure and 6.6 V to the rod with the monolithic structure, the sensitivities of both rods were almost the same. The sandwich structure had a reduced current value and consumed approximately 26 % less power than the monolithic structure. The response time for the sandwich structure and the monolithic structure were comparable, meaning that the insulation layer did not impair the response time.

Experimental demonstration of an electroacoustic transistor

We experimentally demonstrate a topologically protected electroacoustic transistor. We construct a reconfigurable phononic analog of the quantum valley-Hall insulator composed of electrically shunted piezoelectric disks bonded to a patterned plate forming a monolithic structure. The device can be dynamically reconfigured to host one or more topological interface states via breaking inversion symmetry through selective powering of shunt circuits. Above a threshold, the amplitude of wave energy at a chosen location in one topological interface creates a second interface by dynamically switching power between two groups of shunts using relays. This enables the flow of wave energy between two locations in the reconfigured interface analogous to the voltage-controlled electron flow in a field effect transistor. The amplitude of wave energy in the second interface is used for bit abstraction to implement acoustic logic. We illustrate the various states of the transistor and experimentally demonstrate wave-based switching. The proposed electroacoustic transistor is envisioned to find applications in wave-based devices and edge computing in extreme environments and inspire novel technologies leveraging acoustic logic.

LITHOLOGICAL-STRATIGRAPHIC CRITERIA OF KARST ZONING OF THE MIOCENE SULFATE LAYER OF WESTERN UKRAINE

The proposed karst regionalization (zoning) is a novel approach to identifying the unique characteristics of karst processes in specific areas. The sulphate karst of western Ukraine, linked to the Miocene evaporite basin at the junction of the East European Platform and the Pre-Carpathian Foredeep, is a prime example. The previous karst zoning schemes of the East European Plain classified the entire area of sulphate rocks distribution in the west of Ukraine as the Podilsko-Bukovinsky karst Area, with the West Podilsky and Pokutsko-Bukovinsky karst Regions within it. However, with the emergence of numerous detailed stratigraphy works on the evaporite formation of this territory, a new approach to karst zoning in evaporites is necessary. This paper presents a systematic approach to upgrading the mentioned regions to the rank of sub-areas and distinguishing the regions within them based on lithologic-stratigraphic differences. The authors studied six localities as examples. In the first one, the gypsum layer is characterized by the stromatolite, grass-like and sabre-like facies. The last two contain thin carbonate-clay layers, leading to the collapse of large rock blocks inside the Kadubivska Cave. On the second site, the gypsum is composed of stromatolite, coarse-crystalline, and sabre-shaped facies. Only one small Tovtry Cave, which has a hypogene morphology, is known here. The third site has grass-like gypsum facies, and intensive modern karst occurs, with numerous sinkholes, underground rivers, and sinkholes. The influence of facies variability on the development of the mesomorphology of underground galleries is traced here in Pionerka Cave. The fourth area is built of nodular gypsum facies. There are no insoluble layers here, but the facies have many thin mineral films between the grains. Therefore, the entrance parts of the caves are unstable for physical weathering. The fifth section is highlighted as a section of the spread of metasomatic limestone, which replaces sulphate deposits here. They contain a significant cave labyrinth, but whether karstification occurred before or after metasomatization remains unclear. The sixth section is completely composed of stromatolite gypsum facies. It is characterized by stability to collapse due to the monolithic structure of gypsum, which is noticeable in the example of the Cave of Popeliushka (Zolushka) on the border of Ukraine and Moldova. The selected areas are proposed to be considered as examples of karst zoning based on lithologic and stratigraphic features. Key words: karst regionalization; gypsum, limestone; caves, breakdown; relief, landscape.

Study on the Permeability and Mechanical Properties of Sandy Soil Under Carbon Fiber-Based Urease Mineralization

In recent years, soil solidification by EICP method is a green and environmentally friendly foundation treatment technology that has become popular in the field of geotechnical engineering. Compared with the traditional chemical induction method and the MICP method, the EICP method is not easily restricted by environmental factors associated with engineering geological problems and is green and environmentally friendly with lower cost. In this paper, a study was carried out to improve the seepage-mechanical properties of sandy soils by the EICP method. First, soybean urease solution extraction and its performance optimization methods were explored. Tests were conducted to compare urease extraction and detect activity. The activity of urease was 7.1% higher in deionized water than Laoshan mineral water. Second, the EICP grouting mineralization test was performed by using the carbon fiber reinforcement method. The CaCO3 content, unconfined compressive strength, porosity, permeability and other indicators of the sandy soil were systematically analyzed, and microscopic tests were conducted. The test results showed that after carbon fibers were added to the sand, the mineralization effect of EICP led to the precipitation of CaCO3 that adhered to the surfaces of sand grains and fibers and filled and cemented the pores between sand grains, which improved the integrity of the spatial structure and formed a stable solid sand-fiber monolithic composite structure. When the carbon fiber content was 1.2%, all aspects of performance were optimum. The above test results showed that the carbon fiber-based EICP mineralization method could effectively inhibit the brittle failure and improve the permeability and mechanical properties of sandy soil. This method has good application prospects and development potential for use in engineering geology.

A hierarchically cellulose porous monolith doped with CNTs/Al2O3 fibers, exhibiting super-hydrophilicity and underwater superoleophobicity for efficient solar-driven desalination

The utilization of solar-driven interfacial desalination is widely regarded as a promising technological approach for mitigating the global water crisis. Existing solar interface evaporators often face limitations such as salt accumulation and oil waste liquid interference, impeding water supply channels and the efficient escape of interface water vapor, consequently diminishing the evaporation rate. This study proposes a novel approach by synthesizing a monolithic structure composed of carbon nanotubes (CNTs) and vertically arranged Al2O3 fibers which are embedded in cellulose skeleton, achieved through the thermally induced phase separation (TIPS) method. The resulting hierarchically porous monolith exhibits high steam generation rate, remarkable superhydrophilic properties and underwater superoleophobicity, rendering it highly effective in salt tolerance and resistance against oil pollution. In particular, highly oriented Al2O3 fibers form multiple thermal localization arrays and steam dissipation channels，complemented by interconnected hydrophilic skeleton that achieved strong synergy, enabling a stable and high evaporation rate of 1.98 kg m−2 h−1 and 2.06 kg m−2 h−1 in high salt concentration (10 wt%) seawater and oil-in-water (O/W) emulsion, respectively. This work contributes to the ongoing efforts in advancing next-generation solar vapor generators, aiming to enhance the sustainability and efficiency of freshwater production in response to the global water crisis.

Constructing Interfacial Charge Transfer Channels and Electric Field in Violet Phosphorus-Based van der Waals Heterojunction for Phototherapy of Periodontitis.

Periodontitis, a chronic oral disease instigated by bacteria, severely compromises human oral health. The prevailing clinical treatment for periodontitis involves mechanical scraping in conjunction with antibiotics. Phototherapy is employed to rapidly remove the bacteria and achieve periodontitis treatment, effectively circumventing the adverse effects associated with traditional therapies. Constructing 2D/2D van der Waals (VDW) heterojunctions is a key strategy for obtaining excellent photocatalytic activity. Herein, a 2D/2D violet phosphorus (VP)/Ti3C2 VDW heterojunction is designed using an interfacial engineering strategy. By constructing an electron transport "bridge" (P-Ti bond) at the heterogeneous interface as an effective transfer channel for photogenerated carriers, a compact monolithic structure between the VP and Ti3C2 phases is formed, and the spatial barrier for electron transfer at the interface is eliminated. Meanwhile, the strong directional built-in electric field induced by the intensive electron-coupling effect at the heterogeneous interface served as an internal driving force, which greatly accelerates the exciton dissociation and charge transfer in the photocatalytic process. These excited photogenerated electrons and holes are trapped by O2 and H2O on the surfaces of Ti3C2 and VP, respectively, and are subsequently catalytically converted to antibacterial reactive oxygen species (ROS). The VP/Ti3C2 VDW heterojunction eradicated 97.5% and 98.48% of Staphylococcus aureus and Escherichia coli, respectively, by photocatalytic and photothermal effects under visible light for 10 min. The VP/Ti3C2 nanoperiodontal dressing ointment effectively attenuated inflammatory response, reduced alveolar bone resorption, and promoted periodontal soft and hard tissue repair. Its periodontitis therapeutic effect outperforms the clinically used Periocline.

Molecular receptors integrated bimodal porous polymer scaffolds as portable solid-state optical ion-sensors and extractors for the selective capturing of ultra-trace toxic copper ions

BackgroundEnvironmental contamination by heavy metal ions has caused growing ecological and public health concerns. In this line, monitoring of copper toxicity gains importance due to its application in industrial, agricultural, domestic, medical and technological sectors. Although noteworthy breakthroughs were made, critical issues, such as portability, the need for well-trained personnel, costly/complex instrumentations, long response time, and the introduction of secondary contaminants, required attention. Hence, developing a low-cost, user-friendly, real-time, portable analytical platform for rapid and on-site analysis remained imperative. Solid-state colorimetric sensors have gained widespread popularity due to their low cost, ease of use, and brilliant sensitivity/selectivity. ResultsWe have successfully unfolded an ultra-portable azomethine-infused structurally interwoven polymer monolith as the solid-state chromatic sensor for the quantitative naked-eye detection of ultra-trace Cu2+ in industrial/environmental samples. For the sensor fabrication, non-hygroscopic conjugated Schiff-base receptors, namely N-(1E,2E)-3-(4-dimethylamino)phenyl)allylidene)-3-nitrobenzohydrazide (DPAN) and 2,3-bis(((1E,2E)-3-(4-dimethylamino)phenyl)allylidene)amino)malononitrile (DPAM) were synthesized in-house and voluminously immobilized onto a crack-free porous poly(4VP-co-EGDMA) monolith framework. The topological structure and functionalities of the porous polymer monolith and chromatic sensor materials were examined using various surface analytical and microscopic techniques. The excellent surface area and intriguing interlaced porosity features of the tailor-made polymer monolith facilitated the voluminous anchoring of the chromatic receptors for the selective/sensitive targeting of Cu2+. The DPAN and DPAM receptor-loaded poly(4VP-co-EGDMA) sensors exhibited a linear range of 0–150 μg/L, with the limit of detection of 0.11 and 0.13 μg/L for Cu2+, respectively. The sensors manifested Cu2+ specificity amidst concomitant matrix ions to highlight the relevance of the proposed solid-state sensor. SignificanceThe sensor materials offered a reliable approach for detecting and quantifying environmentally toxic and industrially pertinent Cu2+ from aqueous samples, with the prospect of large-scale production, owing to the sensor's integrated compact design that can be reused for repeated real-time surveillance. The sensor's ability to sense/trap traces of toxic Cu2+ can provide an early warning about the growing toxicity in a particular resource, thereby providing an opportunity to initiate remediation protocols for speedy decontamination.

Low-energy spectrum of the BULLKID detector array operated on surface

We present the first continuous operation in a surface lab of BULLKID, a detector for searches of light Dark Matter and precision measurements of the coherent and elastic neutrino-nucleus scattering. The detector consists of an array of 60 cubic silicon particle absorbers of 0.34 g each, sensed by cryogenic kinetic inductance detectors. The data presented focusses on one of the central elements of the array and on its surrounding elements used as veto. The energy spectrum resulting from an exposure of 39 h to ambient backgrounds, obtained without radiation shields, is flat at the level of (2.0±0.1stat.±0.2syst.)×106\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(2.0\\pm 0.1\\,\\mathrm{stat.}\\pm 0.2\\,\\mathrm{syst.})\ imes 10^6$$\\end{document} counts/keV kg days down to the energy threshold of 160±13\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$160\\pm 13$$\\end{document} eV. The data analysis demonstrates the unique capability of rejecting backgrounds generated from interactions in other sites of the array, stemming from the segmented and monolithic structure of the detector.

Micropatterned Hydrogel‐Elastomer Hybrids for Flexible Wet‐Style Superhydrophobic Antifogging Tapes

AbstractTransparent materials widely used in applications such as eyewear, solar cells, and optical devices, often suffer from environmental challenges including fogging, surface contamination, and mechanical deformation. However, a universal strategy that resolves all these issues in a single platform remains to be resolved. Herein, a monolithic micropillar structure based on polydimethylsiloxane (PDMS) elastomer is prepared followed by subsequent assembly of hydrogel micropatterns in between the micropillar array using inkjet printing to achieve flexible wet‐style superhydrophobic antifogging tapes that are applicable to various transparent materials and curvatures. The monolithic micropillar structure with low‐surface‐energy characteristics facilitates easy removal of surface contaminants by rinsing with water while granting mechanical durability. In addition, micropatterning of hydrogels via inkjet printing not only enables to maintain optical transparency in a fogging environment but also makes the fabrication procedure more scalable. Furthermore, the strong adhesion between the hydrogel and the elastomer is shown to provide enhanced stability under repeated stretching cycles and long‐term exposure to water while the presence of a loosely cross‐linked PDMS at the bottom of the tape made it applicable to a wide range of transparent substrates without using additional adhesives.

The Romanian Media System: Dynamics, Challenges, and Implications for Democracy

This article endeavors to delve into the recent transformation of the Romanian media landscape, aiming to offer a nuanced comprehension of the cultural and political dynamics that have influenced journalistic practices. The Romanian media environment has undergone swift changes, transitioning from a monolithic structure to one increasingly driven by commercial interests, all while navigating economic and political pressures. The shift toward a free-market framework has not only reshaped the social and political fabric but has also significantly impacted the media sector. This article posits that the Romanian media landscape is shaped by the interplay of cultural, economic, and political forces, evident in journalistic outputs across both traditional and digital platforms. This assertion aligns with Hallin and Mancini’s (2004) notion of parallelism between journalism and politics. Moreover, it extends this perspective to encompass cultural influences and the evolving media landscape resulting from shifts in the media market, changing consumption patterns, and the proliferation of digital media. Key indicators such as professional standards, editorial autonomy, transparency, financial sustainability, political influence, and media regulations are critically examined within the unique context of Romania, in which political interference and growing reliance on advertising revenue often curtail editorial independence. In conclusion, the article reflects on the current state of the Romanian media system and the manifold challenges it confronts amidst the changing dynamics of the media landscape.

Metro Monolithic Track Bed Vibration Characterization

With the rapid development of cities, metro transportation has also developed rapidly to solve the congestion problems caused by urban development. However, with the continuous development of metro transportation, the vibration problems caused by it have become increasingly obvious. Based on the phonon crystal theory, this paper investigates the vibration characteristics of the metro track structure. It analyzes the influence of the track structure parameters on the band gap characteristics to regulate the metro vibration band gap range. To study the band gap characteristics of metro monolithic bed track structure, establish the double-layer Euler beam model and use the plane wave expansion method (PWE) to calculate its energy band structure; use the finite element method (FEM) to calculate to get its band structure, frequency response function, and time domain analysis. The calculation of PWE shows that there is a band gap in the range of 0–300[Formula: see text]Hz for the metro monolithic track bed, which is 0–194.5[Formula: see text]Hz; the calculation of FEM shows that the range of band gap is 0–193.7[Formula: see text]Hz. Fastening spacing, stiffness, and sub-slab support stiffness will have an impact on the band gap, so appropriate fastening and spacing need to be selected for effective vibration damping of the track structure. The results show that the band gap characteristics of the metro monolithic track bed can be calculated effectively and accurately by using the phononic crystal theory.

ДОСЛІДЖЕННЯ МОДИФІКОВАНОГО В’ЯЖУЧОГО ДЛЯ ВИГОТОВЛЕННЯ ГАЗОБЕТОНУ

In the case of energy saving, the main direction in the technology of modern wall materials is to reduce the density in order to achieve better thermal performance while simultaneously increasing the strength characteristics, i.e. creation of effective wall materials. One of these materials is aerated concrete, which is successfully used all over the world. One of the ways to increase the physical and mechanical properties of the binder as the main component of aerated concrete and to expand the raw material base can be the use of waste from all kinds of production, as well as the secondary use of damaged building materials from destroyed buildings and structures as a result of hostilities (recycling). The purpose of the research is to obtain aerated concrete on a modified binder using recycling of destroyed building materials. At this stage, a modified binder is being studied. As a result of the research, the optimal ratio of the components of the modified binder (Portland cement, metakaolin, brick mortar) was determined. Mathematical models describing the dependence of the bending and compression strength of the binder on its composition were obtained. The results of X-ray phase and differential thermal analysis show that the introduction of methacoaline and brick mortar additives into the binder based on Portland cement, after 28 days of normal hardening, do not cause new phase and mineralogical formations compared to samples without additives, but only affect the quantitative mineralogical storage. More intensively expressed hydro-silicate phases and a decrease in crystallization calcium hydroxide are observed. The micrographs of the structure of the obtained binder clearly show the monolithic structure of the cement stone, the alkali-dispersed cement grains, sand and calcium hydro-silicate clusters are visible.

Assessment of Organizational and Technological Reliability Monolithic Works

Every year in the construction process new technologies are introduced, the use of new building materials increases, a large number of contractors are involved, with a significant increase in the scale of construction and the need to ensure the reliability of construction. There arises a necessity to forecast and correct activities of construction organizations, to give adequate assessments of the adopted organizational and technological solutions (OTS), which, asa rule, leads to a decrease in the prescriptive term of construction. Monolithic structure construction process design is closely connected with the necessity of clear and correct choice of the necessary organizational-technological solutions. Depending on the made decisions it is possible to estimate the reliability of monolithic works. This in its turn gives the possibility to forecast the terms of production, the cost of monolithic works on the stage of design of dwelling buildings and industrial objects directly. The article offers a methodology for calculating the evaluation of organizational and technical reliability of the process of monolithic structures. For the successful performance of monolithic works it is necessary to ensure the reliable functioning of all participants of the process from designers to construction teams. The article presents the calculation of organizational and technological reliability index (OTR) of monolithic works. To calculate the index the author proposed a model and introduced the concept of reliability of the considered process of monolithic works as a probability of achieving the final goal. At the same time, the process of monolithic works performance both for residential and civil objects is taken as a complex stochastic system, which includes a set of co-dependent relations. The application of the assumed approach for the calculation of organizational and technological reliability of monolithic works with small changes, refinements can be applied to the calculation of other works in the construction of buildings and structures throughout the life cycle of construction. At the same time, this methodology makes it possible to obtain a numerical value of reliability assessment, which is very relevant when choosing organizational and technological solutions.

Digital light processing 3D printing of microfluidic devices targeting high-pressure liquid-phase separations.

This paper focuses on 3D printing using digital light processing (DLP) to create microchannel devices with inner diameters of100, 200, and 500 µm and cater flow-through applications within the realm of analytical chemistry, in particular high-pressure liquid chromatographic separations. Effects of layer thickness and exposure time on channel dimensions and surface roughness were systematically investigated. Utilizing a commercially accessible 3D printer and acrylate resin formulation, we fabricated 100-500 µm i.d. squared and circular channel designs minimizing average surface roughness (< 20%) by applying a 20-µm layer thickness and exposure times ranging from 1.1 to 0.7s. Pressure resistance was measured by encasing microdevices in an aluminum chip holder that integrated flat-bottom polyetheretherketon (PEEK)nanoports allowing to establish the micro-to-macro interface to the HPLC instrument. After thermal post-curing and finetuning the clamping force of the chip holder, a maximum pressure resistance of 650bar (1.5% RSD) was reached (n = 3). A polymer monolithic support structure was successfully synthesized in situ with the confines of a 500 µm i.d. 3D printed microchannel. A proof-of-concept of a reversed-phase chromatographic gradient separation of intact proteins is demonstrated using an aqueous-organic mobile-phase with isopropanol as organic modifier.

Integrated hierarchical porous lignin-based carbon electrode for boosting membrane-free capacitive deionization areal adsorption capacity

The development of high value-added lignin-based functional porous carbon electrodes with excellent properties from sustainable industry lignin powder remains a challenge. This work aims to create robust, binder-free, conductive additives-free, and current collector-free monolithic porous carbon electrodes using industrial lignin powder for membrane-free capacitive deionization (CDI). The material exhibits high mechanical strength, hierarchical porosity structure, large uniform size, and thickness of just a few millimetres (<2.6 mm). In a three-electrode supercapacitor system, the areal specific capacitance of CLCA300-3-1.0 reaches 5.03–1.02 F cm−2 when the scan rate between 1 and 20 mV s−1 in 1 M NaCl solution. As CDI electrodes, the charge efficiency of CLCA300-3-1.0 at different voltages of 1.2 V, 1.4 V and 1.6 V is 0.53, 0.72 and 0.71, respectively. The energy consumption of CLCA280-3-1.0, CLCA300-3-1.0 and CLCA320-3-1.0 tested at 1.2 V are 3.27, 3.40 and 3.25 Wh m−3, respectively. In addition, with thickness increasing to 1.5 mm, the developed CLCA300-3-1.5 electrode exhibits an areal adsorption capacity of 0.46 mg cm−2, and relative highly capacity retention of 84.78 % after 70 cycles. The impressive desalination performance is attributed to the well-designed hierarchical porosity, superhydrophilicity and robust monolithic structure.

Optimization of Perovskite/Colloidal Quantum Dot Monolithic Tandem Solar Cell to Enhance Device Performance via Solar Cell Capacitance Simulator 1D

Tandem solar cells (TSCs) based on metal halide perovskites offer a route to increase power conversion efficiency (PCE). However, there are limited options for narrow‐bandgap bottom subcells. Colloidal quantum dots‐based solar cells are found attractive for this role. Herein, a cost‐effective two‐terminal (2T) monolithic TSC structure consisting of wide‐bandgap all‐inorganic perovskite top subcell and narrow‐bandgap chalcogenide PbS quantum dots bottom subcell is proposed. For optimization of the PCE of the tandem structure, standalone and tandem analysis are done in terms of variation of absorber layer thickness, total defect density, interfacial defect density, back metal contact, current density voltage (J–V) curves, external quantum efficiency, current matching, and tandem photovoltaic parameters. Optimized TSCs designed with the 530 nm/450 nm‐thick absorber layers of top/bottom sub cells result in of 19.28 mA cm−2, of 1.89 V, and PCE of 27.32%. It is found that performance of the device is very sensitive to the total defect density of the bottom subcell. Therefore, high PCE can be obtained by controlling the total defect density of the bottom subcell. This work motivates the experimental realization of low‐cost, high‐efficiency TSCs for further research.

Small-scale field experiment on wave forces on a U-OWC breakwater

A small-scale field experiment is conducted on a U-Oscillating Water Column (U-OWC) incorporated into a model of caisson breakwater at the Natural Ocean Engineering Laboratory (NOEL) laboratory of Reggio Calabria (Italy). The U-OWC or REWEC (REsonant Wave Energy Converter) is a device belonging to the family of Oscillating Water Columns (OWCs), characterized by the introduction of a U-duct. Such a device is innovative, absorbing a high percentage of incoming sea energy and, then, to produce electricity via a Power-Take-Off (PTO). The aim of the present study is the investigation of the wave pressures and forces acting on the U-OWC monolithic coastal defense structure. Moreover, the structural response of the U-OWC structure is also investigated under the occurrence of wave crests, by calculating the hydrodynamic forces realized in the active parts of the U-OWC. It is shown as a global additional force is realized, which contributes to increase the overall stability of the structure. Considering the wave loads acting on the U-OWC caisson, the post-process of the overall dataset recorded during the real field experiment at NOEL laboratory reveals the occurrence of both quasi-static loading (non-breaking), and of impact loading (impulsive) due to wave breaking. Thus, a systematic analysis is pursued in order to identify the loading cases acting on the U-OWC breakwater. When high non-breaking sea waves interact with the breakwater, “Quasi-Standing (QS)” wave pressures and forces occur at modified structure with two peaks of equal intensity. Instead, the impact of extreme breaking waves against the U-OWC structure generates asymmetrical wave pressure records beneath the wave crests, with two peaks with different intensity: the first one greater than the second one. In these cases, “Slightly Breaking (SB)” wave forces and “Impact Loads (IL)” are identified. Wave pressure distributions and forces acting on the U-OWC model are, then, investigated for the three classes of wave loads. Moreover, the probability of occurrence of maximum positive peak forces is determined from the experimental dataset, given a number of parameters. In particular, when QSWs occur, the maxima peak forces are recorded for deeper water depths dn, d’ and a, at given significant wave height HSi. Instead, for SBWs and ILs, the extreme wave loads are realized, when the most severe sea states occur with higher HSi , and for decreasing water depth dn. d’ and a. Then, the influence both of the length of the berm and of the width of the U-duct in the front structure is considered. When the dimensions of both structural elements is reduced, the maxima wave forces occur in a fixed recorded sea state. Then, the Quasi-Determinism (QD) nonlinear model at the U-OWC breakwater is introduced for evaluation of Quasi-Standing wave loads, showing a good agreement among analytical and experimental results. Finally, the Goda's model is applied to calculate the wave pressure distributions acting on the external walls of the U-OWC model. The theoretical results given by the Goda's formulae are compared with experimental data, overestimating experimental results for both QSWs and SBWs and, significantly, underestimating IL conditions.

Hierarchical porous cellulose monolith prepared by thermally induced phase separation for high-efficiency uranium adsorption

The development and application of new and efficient adsorption materials are key issues in the treatment of nuclear wastewater. This paper introduces a novel hierarchical porous amidoxime cellulose monolith synthesized through thermally induced phase separation (TIPS). The inherent hydrophilicity of cellulose, combined with the graded porous structure achieved through TIPS (with a specific surface area of 10.36 m2/g), endows the material with strong mass transfer ability. The adsorption properties of this amidoxime cellulose monolith for uranyl ions were evaluated in both batch and flow-through column adsorption scenarios. Remarkably, the adsorption saturation was achieved within a concise period of 13 h in batch adsorption. The hierarchical porous structure of the amidoxime cellulose monolith exhibited exceptional adsorption performance for uranyl ion, achieving a removal rate of 99.99 %. Moreover, this removal rate was sustained for 200 min, and the monolith proved recyclable for at least 5 cycles in flow-through column adsorption tests involving nuclear wastewater. When used for adsorption in real wastewater environments, the material achieved the removal of over 99.96 % of total α and β radioactivity. These findings underscore the high efficiency of the newly developed hierarchical porous amidoxime cellulose monolith in uranyl ion adsorption. They emphasize its substantial potential for the efficient adsorption and removal of uranyl ion from nuclear wastewater.