Search Results (111)

The theory of orientational polarization and dielectric relaxation was developed by P. Debye more than 100 years ago. It approximates a molecule by a sphere having one or more dipole moments. While in the beginning the experimentally accessible spectral range was limited to roughly 6 decades in frequency, at the end of the last century, novel spectroscopic techniques were developed and dielectric spectroscopy became broadband, nowadays covering 18 decades with no gaps.This paved the avenue for a multitude of novel fields of research in soft matter and solid-state physics including fundamental questions like the scaling of relaxation processes or the dynamics of glasses. Yet the analysis of dielectric spectra is still based on the classical approach by Debye which does not consider the multitude of intra- and inter-molecular interactions within a molecular system. To experimentally overcome these principal limitations, it is suggested to take advantage of the molecular specificity of the infrared spectral range. This offers the unique possibility to realize a novel “Orientational Polarization Spectroscopy”, in which the orientational response of a molecular system can be analyzed on an atomistic scale. For that, the theory will be outlined and the first experimental results will be presented. Full article

Heavy metal and cyanide contamination in soil presents serious environmental and ecological concerns due to their persistence, bioavailability, and toxicity to soil biota. In this study, a novel solid-phase direct contact bioassay kit was developed using immobilized Chlorella vulgaris spheres to evaluate the toxicity of soils contaminated with mercury (Hg²⁺), silver (Ag⁺), copper (Cu²⁺), and cyanide (CN⁻). The assay was designed using 25 mL glass vials in which algal spheres were directly exposed to spiked soils for 72 h without the need for pollutant extraction. Oxygen evolution in the headspace was measured as the primary endpoint, alongside optical density and chlorophyll a fluorescence (OJIP) to assess photosynthetic inhibition. The assay demonstrated high sensitivity and reproducibility, with strong correlations (R² > 0.93) between oxygen evolution and optical density. EC₅₀ values based on oxygen evolution were 4.43, 4.18, 3.10, and 61.3 mg/kg for Hg²⁺, Ag⁺, CN⁻, and Cu²⁺, respectively, and 7.8, 7.4, 2.9, and 29.7 mg/kg based on optical density. The relatively higher EC₅₀ for copper was attributed to its biological role as an essential micronutrient. OJIP transient profiles supported the observed photosynthetic inhibition, particularly under Hg²⁺, Ag⁺, and CN⁻ exposure. The present study overcomes the limitations of conventional chemical analyses by providing a rapid, low-cost, and ecologically relevant tool for direct soil toxicity assessment, with potential applications in environmental monitoring and contaminated site evaluation. Full article

The removal of the As(V) and Iprodione fungicide onto EGS@APTES-GT, obtained by amino-modified expanded glass spheres (EGS) modified with goethite, was studied in this work. Material characterization was performed using SEM/EDS, XRD, and FTIR techniques. The adsorption capacities of 51.01 and 94.28 mg g⁻¹, for As(V) and Iprodione removal at 25 °C, respectively, were achieved. A kinetic study indicated lower intraparticle diffusional transport resistance. Physisorption is the dominant mechanism for Iprodione removal, while surface complexation is for As(V). The disposal of effluent water after five adsorption–desorption cycles was attained through Iprodione photocatalytic degradation and arsenate precipitation. Exhausted EGS@APTES-GT, processed by goethite acidic dissolution and grinding, was used as a reinforcing filler in composites production based on commercial unsaturated polyester resin (UPe). An improvement in the mechanical properties was observed, with a gradual increase in the tensile strength, reaching a maximum of 25.9% for UPe with 10 wt.% of ground exhausted adsorbent compared to pure UPe. The overarching concept is defined by the aspiration to develop technologies that address all output flows of advanced processes. Thus, the combination of wastewater treatment technologies and the production of potentially marketable composites successfully achieved both a low environmental impact and the implementation of a circular economy. Full article

We have developed a free-fall type glass sphere underwater observation system with suspended cable. The developed observation system is quite simple to construct and is able to operate at deep sea because the system is structured by glass sphere. The glass sphere has high endurability. Due to no motion system like thrusters, the position of a free-fall type underwater observation system is not clear. And hence, we propose the operation of a free-fall type underwater observation system with a suspended cable like a zipline. To make the position of the system more precise, an inertial measurement unit (IMU) is installed inside the system. A router is also installed inside the system to obtain underwater pictures via a LAN cable. The observation system, which is named UWOS (Under Water Observation System), was operated in the Seto Inland Sea. It was found that the UWOS indicates the possibility of a free-fall type glass sphere underwater observation system with a suspended cable. Full article

Hollow glass microsphere (HGM) reinforced composites are a suitable alternative to energy absorption materials in the automotive and aerospace industries, because of their high crush efficiency and energy absorption characteristics. In this study, a polyurethane elastomeric matrix was reinforced with HGMs for HGM loadings ranging from 0 to 70 vol% (volume fraction). Quasi-static uniaxial compression tests were performed, subjecting the composite to compressive strains of up to 65%, to assess stress vs. strain and energy absorption characteristics. The results reveal that samples with a higher concentration of spheres generally exhibit better crush efficiency. Specifically, the highest crush efficiency was observed in samples with a 70 vol% HGM loading. A similar relationship was reflected in the energy absorption efficiency results, with the highest energy absorption observed in the 65 vol% sample. A correlation exists between the concentration of HGMs and important metrics such as mean crush stress and energy absorption efficiency. However, it is crucial to note that the optimal choice of sphere concentration varies depending on the desired performance characteristics of the material. Full article

Aim: To meta-analyze the utility of transarterial radioembolization (TARE) in patients with liver metastatic breast cancer (BC), based on the objective response rate (ORR) and disease control rate (DCR). Methods: A literature search was performed retrieving studies with (1) at least 10 patients with liver metastatic BC treated with TARE and (2) adequate information to derive ORR and DCR. The ORR is the ratio between patients with liver lesions showing complete response (CR) or partial response (PR) over the total number of patients treated with TARE; the DCR is the ratio between patients with CR, PR, or stable disease (SD) over the total number of patients treated with TARE. Results: Eighteen studies (650 patients) were eligible; the ORR of TARE resulted 50.71% (95% C.I.: 40.04–61.36) and the DCR resulted 88.37% (95% C.I.: 81.89–93.57). Taking into account resin spheres (395 patients), the ORR was 60.35% (95% C.I.: 46.55–73.36) and the DCR was 92.73% (95% C.I.: 87.17–96.80%). Considering glass spheres (144 patients), the ORR was 32.38% (95% C.I.: 18.43–48.16) and the DCR was 82.69% (95% C.I.: 59.29–97.26). Conclusions: This meta-analysis favors the use of TARE in patients with liver metastatic BC either with resin or glass spheres. Full article

Phenolic antioxidants such as tert-butylhydroquinone (TBHQ) can prolong the shelf life of edible oils by delaying the oxidation process. The excessive use of TBHQ can damage food quality and public health, so it is necessary to develop an efficient TBHQ detection technique. In this work, nickel-aluminum double hydroxide (NiAl-LDH) was grown on glucose carbon spheres (GC), which formed porous carbon nanomaterials (named NiAl-LDH@GC-800) after pyrolysis at 800 °C. The successful synthesis of the material was verified by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The obtained NiAl-LDH@GC-800 was dopped onto a glass carbon electrode to prepare an electrochemical sensor for TBHQ. The synergistic effect of porous carbon and Ni metal reduced from NiAl-LDH by high-temperature calcination accelerated the electron transfer rate and improved the sensitivity of the sensor. The prepared sensor showed a low limit of detection (LOD) of 8.2 nM, a high sensitivity (4.2 A·M⁻¹), and a good linear range (20~300 µM) in detecting TBHQ. The sensor was also successfully used for TBHQ detection in edible oils, including chili oil, peanut oil, and rapeseed oil. Full article

This article’s aim is to analyze physical, mechanical, and fracture properties as well as the thermal investigation of geopolymer composites reinforced with flax, glass fiber, and also the hybrid combination of fibers. Two types of matrices were considered as composites matrices. The first composition was based on fly ash and river sand. The second matrix composition contained fly ash and glass spheres. The content of reinforcement was 1% by mass. Compressive strength and three-point bending fracture tests were performed. The values of fracture toughness and fracture energy were determined. The resonance method was used to verify the dynamic characteristics, such as the dynamic modulus of elasticity and the dynamic Poisson ratio. The results show that single-type fibers in composites based on fly ash and glass spheres did not affect compressive strength. However, introducing hybrid reinforcement increased compressive strength by about 10% compared to the reference specimens. Flax fibers and hybrid reinforcement ensured higher fracture toughness and energy. The results also revealed great potential for glass sphere application to geopolymer materials in terms of fracture mechanics and thermal properties. Despite the lower strength properties in relation to geopolymers based on sand aggregate, applying reinforced fibers into the composite with glass spheres enhanced the compressive strength compared to other materials. Materials modified with glass spheres have a thermal conductivity twice as low as that of materials containing river sand. Full article

In this work, we theoretically and experimentally study the induction of electromagnetic forces in an opal-based magnetic photonic glass, where light normally impinges onto a disordered arrangement of SiO₂ spheres by the aggregation of Fe₃O₄ nanoparticles. The working wavelength is 633 nm. Experimental evidence is presented for the force that results from forced oscillations of the photonic structure. Finite-element method simulations and a theoretical model estimate the magnetic force volumetric density value, peak displacement, and velocity of oscillations. The magnetic force is of the order of 56 microN, which is approximately 500-times higher than forces induced in dielectric optomechanical photonic crystal cavities. Full article

Polymer matrix solid buoyancy materials (PSBMs) have the advantages of low density, high strength, low cost, and low water absorption, and they are widely used in marine engineering fields. How to improve the performance of PSBMs further and adapt them to harsh marine environments has become a hot topic in current research. This paper provides a comprehensive summary of PSBM, detailing both the preparation methodologies and properties of single-component and multi-component PSBM. In this paper, relevant research is systematically summarized from two dimensions of matrix and filler, and the application of thermosetting resin and thermoplastic resin as a matrix in PSBM is introduced in detail, and the corresponding research on fillers such as hollow glass microspheres, fly ash, hollow ceramic spheres and hollow polymer microspheres are expounded. This paper aims to summarize the latest advancements in PSBM research, thereby providing insights into the current state of the field and guiding future investigations. Full article

This study introduces an innovative surgical approach for total knee arthroplasty (TKA) that combines kinematic alignment (KA) principles with real-time elongation of the knee ligaments through the range of motion, using augmented reality (AR). The novelty of the surgical technique lies in the possibility of enhancing the decision-making process to perform the cut on the tibia as for the KA caliper technique developed by Dr. Stephen Howell. The NextAR is a CT-based AR system that offers the possibility of performing three-dimensional surgical preoperative planning and an accurate execution in the surgical room through single-use infrared sensors, smart glasses, and a control unit. During the preoperative planning, the soft tissue is not considered and only the alignment based on bony reference is ensured. Thanks to the possibility of measuring in real time the elongation of the knee collateral lateral ligaments, the system assists the surgeon in optimizing the cut on the tibia after an accurate resurfacing of the femur as described in the KA surgical technique. The implant used in this novel approach is a medial pivot design (Medacta GMK Sphere) that allows the restoration of the physiological behavior of the software tissue and natural knee kinematics. In conclusion, this novel technique offers a promising approach to TKA, allowing personalized treatment tailored to each patient’s unique anatomy and soft tissue characteristics. The integration of KA and real-time soft tissue analysis provided by NextAR enhances surgical precision and outcomes, potentially improving patient satisfaction and functional results. Full article

Froth flotation predominantly separates particles according to their differences in wettability. However, other particle properties such as size, shape or density significantly influence the separation outcome as well. Froth flotation is most efficient for particles within a size range of about 20–200 μm, but challenges arise for very fine or coarse particles that are accompanied by low recoveries and poor selectivity. While the impact of particle size on the separation behavior in flotation is well known by now, the effect of particle shape is less studied and varies based on the investigated zone (suspension or froth) and separation apparatus used. Beyond these complexities, many particle properties are correlated, making it challenging to analyze the isolated impact of individual properties on the separation behavior. Therefore, a multidimensional perspective on the separation process, considering multiple particle properties, enhances the understanding of their collective influence. In this paper, the two-dimensional case is studied; i.e., a parametric modeling approach is applied to determine bivariate Tromp functions from scanning electron microscopy-based image data of the feed and the separated fractions. With these functions it is possible to characterize the separation behavior of particle systems. Using a model system of ultrafine (<10 μm) particles, consisting of either glass spheres or glass fragments with different wettability states as the floatable fraction and magnetite as the non-floatable fraction, allows for the investigation of the influence of descriptor vectors consisting of size, shape and wettability, on the separation. In this way, the present paper contributes to a better understanding of the complex interplay between certain descriptor vectors for the case of ultrafine particles. Furthermore, it demonstrates the benefits of using multivariate Tromp functions for evaluating separation processes and points out the limitations of SEM-based image measurements by means of mineral liberation analysis (MLA) for the studied particle size fraction. Full article

This study explores the influence of flow velocity, sphere size, and inter-sphere distance on hydrodynamics and mass transfer in a photocatalytic reactor. The effects of two different light configurations on light distribution and degradation were also evaluated. A 2D computational fluid dynamics (CFD) model was developed to simulate the continuous flow photocatalytic reactor with TiO₂-coated spheres and validated with experimental measurements by observing the degradation of methyl orange. The experimental setup consists of a tube containing an equal number of TiO₂-coated glass spheres. The case with radiation from one wall shows a non-uniform light distribution compared with the case with radiation from both walls. The CFD simulations focused on analyzing the velocity streamlines and turbulence characteristics (turbulent kinetic energy (TKE) and turbulence dissipation rate (TDR)). These parameters showed significant variations in each studied case. The case with larger spheres reached the highest velocity of 38 m/s of the pollutant solution. The highest TKE and TDR values of 0.47 m²/s² and 12.2 m²/s², respectively, were also observed in the same case, indicating enhanced mixing and mass transfer to the catalyst surfaces, ultimately leading to a more efficient degradation process. The results show that an optimized design of photocatalytic reactors can significantly improve mass transfer and, thus, degradation efficiency. Full article

The KM3NeT Collaboration is building an underwater neutrino observatory at the bottom of the Mediterranean Sea, consisting of two neutrino telescopes, both composed of a three-dimensional array of light detectors, known as digital optical modules. Each digital optical module contains a set of 31 three-inch photomultiplier tubes distributed over the surface of a 0.44 m diameter pressure-resistant glass sphere. The module also includes calibration instruments and electronics for power, readout, and data acquisition. The power board was developed to supply power to all the elements of the digital optical module. The design of the power board began in 2013, and ten prototypes were produced and tested. After an exhaustive validation process in various laboratories within the KM3NeT Collaboration, a mass production batch began, resulting in the construction of over 1200 power boards so far. These boards were integrated in the digital optical modules that have already been produced and deployed, which total 828 as of October 2023. In 2017, an upgrade of the power board, to increase reliability and efficiency, was initiated. The validation of a pre-production series has been completed, and a production batch of 800 upgraded boards is currently underway. This paper describes the design, architecture, upgrade, validation, and production of the power board, including the reliability studies and tests conducted to ensure safe operation at the bottom of the Mediterranean Sea throughout the observatory’s lifespan. Full article

Functional cyclophosphazenes have proven to be effective modifiers of polymer materials, significantly improving their performance properties, such as adhesive characteristics, mechanical strength, thermal stability, fire resistance, etc. In this study, 4-(β-carboxyethenyl)phenoxy-phenoxycyclotriphosphazenes (CPPP) were obtained by the condensation of 4-formylphenoxy-phenoxycyclotriphosphazene with malonic acid. Its structure was studied using ³¹P, ¹H, and ¹³C NMR spectroscopy and MALDI-TOF mass spectrometry, and the thermal properties were determined by DSC and TGA methods. Molecular modeling using the MM2 method showed that CPPPs are nanosized with diameters of spheres described around the molecules in the range of 1.34–1.93 nm, which allows them to be classified as nanosized structures. The epoxy resin DER-331 was cured with CPPP, and the conversion of epoxy groups was assessed using IR spectroscopy. Using optical interferometry, it was shown that CPPPs are well compatible with epoxy resin in the temperature range from 80 to 130 °C. It was established that the cured epoxy composition was fire resistant, as it successfully passed the UL-94 vertical combustion test due to the formation of porous coke during the combustion process and also had high heat resistance and thermal stability (decomposition onset temperature about 300 °C, glass transition temperature 230 °C). The composition has low water absorption, high resistance to fresh and salt water, fire resistance, and adhesive strength to steel and aluminum (11 ± 0.2 MPa), which makes it promising for use as an adhesive composition for gluing parts in the shipbuilding and automotive industries, the aviation industry, and radio electronics. Full article