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Non-conventional machining processes are capable of achieving higher performance compared to conventional ones due to their inherent characteristics and higher amount of parameters which can be favorably regulated. Although the correlation between the most important process parameters and process outcome has been already established for a wide range of conditions and workpiece materials, the introduction of new considerations related to the three pillars of sustainability require further investigation on new means for the enhancement of AWJ milling process. As one of the most important parameters in AWJ milling is the abrasive material, the introduction of new materials may offer considerable advantages from different perspectives. Thus, in the present work, a comprehensive investigation on the efficiency of using eco-friendly, mixed abrasives is carried out under various conditions such as different traverse feed rate, abrasive mass flow rate, water jet pressure, jet impingement angle, and mixing ratio. The feasibility of using mixed abrasives is evaluated in terms of achievable depth of penetration, kerf width, kerf taper angle as well as material removal rate (MRR), and cutting efficiency. The findings indicate that among other factors, the mixing ratio plays a noticeable role especially regarding MRR and cutting efficiency and can offer an additional effective means to achieve the desired kerf characteristics in conjunction with other significant parameters such as water jet pressure. [ABSTRACT FROM AUTHOR]

Very little information exists on the particle and chemical contamination of consumer (horticultural) composts. In this study, anthropogenic microcellulosics (AMCs), microplastics (MPs) and other microscopic debris, along with anthropogenically impacted metals (Cu, Zn, Pb), have been determined in 12 composts (seven garden composts and five growbags) purchased at outlets in the UK. AMCs and MPs, determined microscopically, were present in all samples at up to about 1100 kg−1 dw. AMCs were more abundant and were dominated by fibres constructed of rayon and cotton, while petroleum-based MPs exhibited a greater diversity in shape and polymeric construction (including polyolefins, polyethylene terephthalate, polyvinyl chloride, resins, paints and rubbers). Other microdebris, present in much smaller concentrations in the composts, consisted of fragments of glass, metal and machined wood and spherical glass beads. Concentrations of the anthropogenically impacted metals, Cu, Pb and Zn, determined directly by energy-dispersive X-ray fluorescence spectrometry, were heterogeneously distributed and averaged 52.4, 192 and 51.6 mg kg−1 dw, respectively. Although concentrations of anthropogenic particles were not related to cost or type of compost, physico-chemical properties or metal concentrations, a significant relationship between Pb content and particle diversity (number of polymers and debris types) was established. This relationship might result from the general contamination of the environment by both Pb and anthropogenic particulates, or the association of the metal with various types of material (e.g. paints, polyvinyl chloride, glass). Despite the ubiquity and diversity of MPs and microdebris in consumer composts, an understanding of their impacts on plant growth, either directly or indirectly (e.g. by interacting with metals), is unknown. [ABSTRACT FROM AUTHOR]

Glass beads first appear in the archaeological record of southern Africa around the mid-first millennium CE, marking the earliest signatures of extensive connections between the southern African region, the East African coast, and the broader Indian Ocean rim. Key research focused on glass beads, particularly from notable southern African polities, like the renowned Mapungubwe and Great Zimbabwe sites, has laid the groundwork for a regional taxonomic series of these beads, emphasizing their role as indicators of wealth and social status. This paper introduces new data on 59 glass beads from a recently excavated and lesser-known Zimbabwe culture site in the Mberengwa region of south-central Zimbabwe. The analysis employs non-invasive techniques, including typological classification and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The investigation identifies six glass bead series from Chumnungwa, composed of plant ash-lime (v-Na-Ca), vegetable soda-high alumina (v-Na-Al), and soda-based glasses with high-alumina concentrations (m-Na-Al). These beads, widely distributed in Asia and Africa between the eight and seventeenth centuries, shed new light on the geochemistry, provenance, and circulation patterns of glass beads in southern Africa, particularly within a community situated beyond the well-known Iron Age polities. Notably, Chumnungwa emerges as the first known Zimbabwe culture site in southern Africa to yield m-Na-Al 6 glass beads. However, as recently demonstrated at the Toutswe sites in Botswana, it is probable that other Zimbabwe culture sites in the region also possessed m-Na-Al 6 glass beads. These beads may have been misclassified as m-Na-Al 2 glass since this group was only recently unveiled on the East African coast, after the bulk of the currently available literature had been published. Insights drawn from contextual recovery data and Shona anthropology form the basis for an extended discussion on the consumption and sociality of glass beads in Iron Age southern Africa. Ultimately, the study underscores the challenge of typologically categorizing beads into established series without the application of LA-ICP-MS and other scientific approaches. [ABSTRACT FROM AUTHOR]

This article discusses the discovery of bronze weights in the form of a cuboctahedron, one of the thirteen Archimedean solids, in northwestern Russia. These weights, dating back to the eighth to tenth centuries, were found near the village of Staraya Ladoga, an important historical trading center in Eastern Europe. The article explores the history of Ladoga, its role as a trading center, and the Middle Eastern origin of the cuboctahedron weights. It also discusses the dissemination of knowledge about Archimedean solids through Arabic/Persian culture and their later rediscovery in Europe. [Extracted from the article]

This study aims to investigate the flow characteristics of water–sand mixture in fractured porous media through a series of laboratory experiments. The experiments focus on examining the transport characteristics of water–sand mixture with varying grain sizes, glass bead gradations, sand mass fraction and outlet conditions. The results show that an increase in grain size causes a more pronounced nonlinear variation in large pressure gradient, resulting in a predominantly longitudinal flow pattern with a 'multi-arc' flow state. Water–sand mixture with various glass bead gradations exhibits aggregation effects in porous media. The discrete element method–computational fluid dynamics (DEM–CFD) two-way coupling method is used to simulate water–sand flow in fractured porous media using the three-dimensional particle flow code (PFC3D). The simulation shows that the fracture has a more significant constraint effect than the pore due to the significant variation in internal contact force. A response surface optimization method is utilized to establish multi-factor response models. The correlation between flow, fracture inlet pressure, pore inlet pressure and water–sand mass is analyzed to predict accurately the variation of water–sand outflow. Based on the least square method, multivariate regression fitting equations are developed using sand grain size, gradation and sand mass fraction to predict the dynamics of fluidity I and non-Darcy factor β. The equations are found to be effective in forecasting the dynamics of these factors and provides valuable insights for assessing. These results can be used to predict the movement behavior of fluid in fracture-pore composite media and provide theoretical guidance for preventing disasters such as water–sand inrush. Highlights: A shift in the flow pattern of water-sand mixture from a grid-like structure to a multi-arc structure is found as the size of sand particles increases. Water–sand flow in fracture–pore channel is established based on the DEM–CFD two-way coupling method. Multi-factor response models for water-sand outflow are established by using the method of response surface optimization. Multiple regression fitting equations are established based on the least squares method to predict the evolution of fluidity I and non-Darcy factor β. [ABSTRACT FROM AUTHOR]

Phycocyanin is an interesting alternative to synthetic food colorants. Various methods to obtain phycocyanin from Arthrospira (Spirulina) biomass have been described in the literature, including ultrasonication, glass bead extraction and freeze-thawing. In this study, three optimized procedures were implemented to assess their efficacy in obtaining phycocyanin from Arthrospira maxima biomass, facilitating a comparative analysis of their effectiveness. After harvesting the biomass, extraction processes were conducted utilizing ultrasonication followed by flocculation with chitosan in various organic acid solutions, as well as glass bead extraction and freeze-thawing techniques, each followed by centrifugation. The obtained extracts were analyzed spectrophotometrically across the wavelength range of 280 to 800 nm. The freeze-thawing method yielded the highest C-PC contents at 17.03 ± 0.53%, followed closely by the ultrasonication method at 15.21 ± 0.41%. The highest purity of 2.02 ± 0.01 was attained through ultrasonication and subsequent flocculation with chitosan in acetic acid. Conversely, employing chitosan dissolved in citric or lactic acid for flocculation resulted in greenish extracts containing high amounts of chlorophyll. [ABSTRACT FROM AUTHOR]

The possibility of fixing velocities of fluid motion in model porous medium (glass beads) by measuring the transverse relaxation time T2 by spin echo method is shown. The magnetic field gradient arising due to the difference in the magnetic permeability of the fluid and the porous medium causes a decrease in the average time T2, which makes it possible to fix the fluid motion in the absence of an external magnetic field gradient. The addition of magnetic nanoparticles to the fluid under study increases the dependence of T2 on fluid velocity and increases the sensitivity in determining the permeability of porous medium by NMR-relaxometry. [ABSTRACT FROM AUTHOR]

The focus of this study is the experimental characterization of cemented granular materials, with the aim of identifying the microscopic properties of the solid bonds and describing the extension to macroscopic mechanical strength of cemented samples. We chose to use artificially bonded granular materials, made of glass beads connected by solid paraffin bridges. The results of several sets of laboratory tests at different scales are presented and discussed. Micromechanical tests investigate the yield strength of single solid bonds between particles under traction, shearing, bending and torsion loading, as a function of variations in particle size, surface texture and binder content. Macro-scale tensile tests on cemented samples explore then the scale transition, including influence of confining walls through homothetic variations of the sample size. Despite the large statistical dispersion of the results, it was possible to derive and validate experimentally an analytical expression for micro tensile yield force as a function of the binder content, coordination number and grain diameter. In view of the data, an adhesive bond strength at the contact between bead and solid bond is deduced with very good accuracy and it is even reasonable to assume that the other threshold values (shear force, bending and torsion moments) are simply proportional to the tensile yield, thus providing a comprehensive 3D model of cemented bond. However, the considerable dispersion of the data at the sample scale prevents validation of the extended model for macroscopic yield stress. A final discussion examines the various factors that may explain intrinsic variability. By comparison with other more realistic systems studied in the literature in the context of bio-cementation, our artificial material nevertheless appears suitable for representing a cemented granular material. Being easy to implement, it could thus enable the calibration of discrete cohesion models for simulation of practical applications. [ABSTRACT FROM AUTHOR]

Microbially induced carbonate precipitation (MICP) is a potential method for ground improvement. It can enhance the physical and mechanical properties of soils through soil particle cementation and pore filling. However, the excessive number of injections of cementing solution required for MICP is a major limitation for practical engineering application. To reduce the number of injections and improve the efficiency of the cementing process, an enhancement method was investigated in this study in which an aluminum ion flocculant (AIF) was added to the cementing solution. It can enhance the curing rate and effect of MICP. Experiments were carried out on MICP-treated sand columns, MICP-treated glass beads and aqueous solutions, and the influence of AIF on the production of calcium carbonate and unconfined compressive strength (UCS) was studied. The effect of AIF on the composition and morphology of the deposited calcium carbonate was evaluated from SEM micrographs and other microscopic observations. The results of the study showed that the addition of AIF to the cementing solution significantly reduced the number of injections required and increased the UCS of the reinforcement compared to those of a control group without adding AIF. The proposed method resulted in the experimental sand column being reinforced after 3 treatments of the cementing solution with an UCS of 323.3 kPa. The UCS reaches 1692 kPa after 5 treatments of the cementing solution, compared to 9 treatments using the conventional method. The UCS was 3.2–12.7 times higher than that of the control group for the same calcium carbonate content. [ABSTRACT FROM AUTHOR]

Visualising fluid flow in porous media using optical techniques is challenging due to the inability to see through the medium. Here, we present an experimental methodology based on shadowgraphy to investigate the dynamic spreading of convective plumes in saturated transparent porous media made of glass beads. The saturated porous medium can be tuned transparent by matching the refractive index of the solid glass beads to that of the saturating fluid mixture. The proposed technique allows to investigate the essential elements of convective mixing within a porous medium using miscible fluids. We also describe a method to determine the velocity of convective plumes as they propagate. Our experimental results show that the density difference achieved during convection significantly affects the convective front velocity of the plumes. This is significant because it allows to quantitatively predict the intensity of convective mixing in porous media from the speed of the convective front. Article Highlights: Shadowgraphy has been successfully used to investigate fluid flow in transparent porous media. Convective front velocities are used to evaluate quantitatively convective mixing in porous media. In the fluid flow regime of our experiment, we observed a super-linear scaling of the convective front velocity and density difference. [ABSTRACT FROM AUTHOR]

Mycotoxin production by aflatoxin B1 (AFB1) -producing Aspergillus flavus Zt41 and sterigmatocystin (ST) -hyperproducer Aspergillus creber 2663 mold strains on corn and rice starch, both of high purity and nearly identical amylose-amylopectin composition, as the only source of carbon, was studied. Scanning electron microscopy revealed average starch particle sizes of 4.54 ± 0.635 µm and 10.9 ± 2.78 µm, corresponding to surface area to volume ratios of 127 1/µm for rice starch and 0.49 1/µm for corn starch. Thus, a 2.5-fold difference in particle size correlated to a larger, 259-fold difference in surface area. To allow starch, a water-absorbing powder, to be used as a sole food source for Aspergillus strains, a special glass bead system was applied. AFB1 production of A. flavus Zt41 was determined to be 437.6 ± 128.4 ng/g and 90.0 ± 44.8 ng/g on rice and corn starch, respectively, while corresponding ST production levels by A. creber 2663 were 72.8 ± 10.0 µg/g and 26.8 ± 11.6 µg/g, indicating 3–fivefold higher mycotoxin levels on rice starch than on corn starch as sole carbon and energy sources. Key points: • A glass bead system ensuring the flow of air when studying powders was developed. • AFB1 and ST production of A. flavus and A. creber on rice and corn starches were studied. • 3–fivefold higher mycotoxin levels on rice starch than on corn starch were detected. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced cement-based material incorporating hollow glass beads (GFRC-HGB) is an innovative lightweight building material with exceptional energy-saving properties. Based on the framework of variational asymptotic homogenization theory, a micromechanical model is developed for predicting the effective elastic properties and recovering the local fields of unidirectional GFRC-HGB. This model starts with expressing the displacements of the heterogeneous GFRC-HGB in terms of those of the corresponding homogeneous material and fluctuation function. Then, the principle of minimum potential energy is used along with variation asymptotic method to formulate the governing variational statement for the micromechanics model, the micromechanical model is used to quantitatively investigate the influence of internal structural parameters of HGB on the elastic properties of unidirectional GFRC-HGB. The numerical results demonstrate the effectiveness and accuracy of the micromechanical model in predicting the effective elastic modulus and local fields. The numerical simulation and SEM images of the tensile fracture prove that the local stress distributions are closely related to the loading direction, and the transverse deformation is restrained by glass fibers. [ABSTRACT FROM AUTHOR]

Soil particles possess highly complex particle morphology, including particle shape and surface roughness, which have a significant impact on mechanical responses of granular materials, such as packing characteristics, small-strain stiffness and stress–strain responses. However, there has been little or no quantitative investigation on the combined effect of particle shape and surface roughness. This contribution carries out triaxial compression tests using six differently shaped granular materials under dry and drained conditions. Meanwhile, the surface texture is carefully treated to vary the degree of surface roughness for each material. Samples are prepared under a similar initial void ratio (e0) or relative density (Dr0) to eliminate the density-dependency. Samples prepared under the same sample preparation method with a given tapping number (Nt) during the sample preparation process are also considered. The experimental results show that more irregular materials tend to show greater values of deviator stresses at the peak state (qpeak) and an axial strain of 15% ( q ε a = 15 % ), and display a more gradual development of stress and a later appearance of qpeak. Except for clumped glass beads, increasing surface roughness leads to an increase in stress levels during shearing, which is more marked in irregular materials. In addition, materials with more spherical shapes or rougher surfaces demonstrate an earlier phase transformation point (εa,ptp) and an earlier occurrence of peak stress (εa,peak). [ABSTRACT FROM AUTHOR]

The glass compound eye bead is the exquisite embodiment of the glassmaking technology of ancient craftsmen, and is an example of the cultural exchange between China and the West during the Warring States Period. This study takes two dots and mesh beads with seriously weathered surfaces excavated from Hejia village, Zhouling as the research object. Micromorphology, X-ray fluorescence spectroscopy (XRF), microscopic laser Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were respectively used to determine the chemical elements, valence states and compositions of the glass matrix and its weathering products. In this study, the valence state analysis of group-d elements is used to reveal the electron transition mode and explain the colour formation reason of blue-black glass matrix. In terms of weathering products, in addition to the identification of common cerusite [PbCO3] and barite [BaSO4], the study also found the blue weathering product alforsite [Ba5(PO4)3Cl] for the first time. The study also makes reasonable assumptions about the reasons for their appearance. The X-ray photoelectron spectroscopy (XPS) used in this study has positive significance for the study of the formation mechanism of glass colour. The scientific and technological analysis data of these two glass beads provide basic data for the related research of the lead-barium glass system produced in China, and also provide a certain scientific basis for the related protection research. [ABSTRACT FROM AUTHOR]

Particle size measurement is crucial in various applications, be it sizing droplets in inkjet printing or respiratory events, tracking particulate ejection in hypersonic impacts or detecting floating target markers in free-surface flows. Such systems are characterised by extracting quantitative information like size, position, velocity and number density of the dispersed particles, which is typically non-trivial. The existing methods like phase Doppler or digital holography offer precise estimates at the expense of complicated systems, demanding significant expertise. We present a novel volumetric measurement approach for estimating the size and position of dispersed spherical particles that utilises a unique 'Depth from Defocus' (DFD) technique with a single camera. The calibration-free sizing enables in situ examination of hard to measure systems, including naturally occurring phenomena like pathogenic aerosols, pollen dispersion or raindrops. The efficacy of the technique is demonstrated for diverse sparse dispersions, including dots, glass beads and spray droplets. The simple optical configuration and semi-autonomous calibration procedure make the method readily deployable and accessible, with a scope of applicability across vast research horizons. [ABSTRACT FROM AUTHOR]

Gravitational instabilities occurring at the interface between a suspension of granular particles and a clear fluid are studied experimentally using a sealed Hele–Shaw cell. Special attention is paid to the effects of particle Reynolds number (Re) and the initial particle packing on the growth of the interfacial perturbation. Glass beads are immersed in the glycerin–water mixture and are placed at the bottom of the cell initially. The mass content of the glycerin in fluid mixtures is varied to obtain the desired fluid viscosities and thus the Re value. The cell is then inverted to place the suspension above the fluid to trigger the gravitational instabilities. When the particle packing is dense, the distinct interface separating the fluid transforms progressively into an asymmetrical cusp-shaped structure. In contrast, when the packing is loose, the interface between the fluid and suspension takes on a symmetrical sinusoidal form initially and evolves into a mushroom-like pattern reminiscent of the canonical Rayleigh–Taylor instability. The growth rate of this symmetrical perturbation observed for loose packing surpasses that of its asymmetrical counterpart at the equivalent Re. Both types of perturbations exhibit larger growth rates with increasing Re. Linear stability analysis adapted to the loose packing configuration predicts a growth rate that is comparable to the observed rate during the initial growth of the symmetrical perturbation and suggests a similar dependence on Re. [ABSTRACT FROM AUTHOR]

Passive daytime radiative cooling (PDRC) is an emerging nonpolluting, nonenergy-consuming cooling technology that relies on high reflectivity in the solar band and high emissivity in the infrared band. As an outdoor-oriented cooling material, its mechanical durability and optical stability are of great significance for long-term application. Herein, we fabricated a superhydrophobic polydimethylsiloxane-based film filled with regular hollow glass beads simply by blending, coating, and drying without using any solvents, followed by surface sanding. The hollow glass beads made the film possess regular hollow structures enabling the surface to maintain the superhydrophobic and optical properties even after severe abrasion. The as-fabricated film boasts a solar reflectance of 96.0%, a mid-infrared emissivity of 97.8% and a water contact angle of 163.9°, and achieves a cooling effect of 11.7 °C under direct sunlight. Additionally, these films can be applied as coatings to various substrates and offer appealing features such as self-cleaning, chemical stability, and weather resistance, making them highly suitable for outdoor applications. The entire preparation process is nontoxic and does not involve organic solvents, thereby expanding the range of preparation methods and application fields for PDRC materials. [ABSTRACT FROM AUTHOR]

Background: A dual-function phantom designed to quantify the apparent diffusion coefficient (ADC) in different fat contents (FCs) and glass bead densities (GBDs) to simulate the human tissues has not been documented yet. We propose a dual-function phantom to quantify the FC and to measure the ADC at different FCs and different GBDs. Methods: A fat-containing diffusion phantom comprised by 30 glass-bead-containing fat-water emulsions consisting of six different FCs (0, 10, 20, 30, 40, and 50%) multiplied by five different GBDs (0, 0.1, 0.25, 0.5, and 1.0 g/50 mL). The FC and ADC were measured by the "iterative decomposition of water and fat with echo asymmetry and least squares estimation-IQ," IDEAL-IQ, and single-shot echo-planar diffusion-weighted imaging, SS-EP-DWI, sequences, respectively. Linear regression analysis was used to evaluate the relationship among the fat fraction (FF) measured by IDEAL-IQ, GBD, and ADC. Results: The ADC was significantly, negatively, and linearly associated with the FF (the linear slope ranged from -0.005 to -0.017, R2 = 0.925 to 0.986, all p < 0.001). The slope of the linear relationship between the ADC and the FF, however, varied among different GBDs (the higher the GBD, the lower the slope). ADCs among emulsions across different GBDs and FFs were overlapped. Emulsions with low GBDs plus high FFs shared a same lower ADC range with those with median or high GBDs plus median or lower FFs. Conclusions: A novel dual-function phantom simulating the human tissues allowed to quantify the influence of FC and GBD on ADC. Relevance statement: The study developed an innovative dual-function MRI phantom to explore the impact of FC on ADC variation that can affect clinical results. The results revealed the superimposed effect on FF and GBD density on ADC measurements. Key points: • A dual-function phantom made of glass bead density (GBD) and fat fraction (FF) emulsion has been developed. • Apparent diffusion coefficient (ADC) values are determined by GBD and FF. • The dual-function phantom showed the mutual ADC addition between FF and GBD. [ABSTRACT FROM AUTHOR]

Microfluidic systems with integrated sensors are ideal platforms to study and emulate processes such as complex multiphase flow and reactive transport in porous media, numerical modeling of bulk systems in medicine, and in engineering. Existing commercial optical fibre sensing systems used in integrated microfluidic devices are based on single-core fibres, limiting the spatial resolution in parameter measurements in such application scenarios. Here, we propose a multicore fibre-based pH system for in-situ pH mapping with tens of micrometer spatial resolution in microfluidic devices. The demonstration uses custom laser-manufactured glass microfluidic devices (called further micromodels) consisting of two round ports. The micromodels comprise two lintels for the injection of various pH buffers and an outlet. The two-port system facilitates the injection of various pH solutions using independent pressure pumps. The multicore fibre imaging system provides spatial information about the pH environment from the intensity distribution of fluorescence emission from the sensor attached to the fibre end facet, making use of the cores in the fibre as independent measurement channels. As proof-of-concept, we performed pH measurements in micromodels through obstacles (glass and rock beads), showing that the particle features can be clearly distinguishable from the intensity distribution from the fibre sensor. [ABSTRACT FROM AUTHOR]

The determination of elemental impurities in uranium ore concentrates (UOCs) is of great importance in the fields of nuclear forensics and nuclear safeguards and more generally for the nuclear industry. To avoid the use of chemical reagents, prevent waste generation, and reduce the duration of the analysis, a simple method based on sample preparation involving the conversion of UOCs into glass beads by alkaline fusion followed by direct measurement by laser ablation—sector-field ICP-MS (LA-ICP-MS) is proposed. External calibration was performed with a mix of UOCs and geological standard reference materials. Accurate results were obtained for most of the 48 elements of interest in six UOC materials. The lowest detection limits are in the ng g−1 range. With this method, concentrations of a wide range of elements can be determined within 24 h. [ABSTRACT FROM AUTHOR]

The spatial distribution of filler particles and their agglomeration depending on concentration and size was studied. In all cases, silica particles served as filler. The particle size varied over a wide range, from nanoparticles to glass beads, and therefore the filler particles have the same nature. An amorphous polymer (polysulfone) and a crystallizing polymer (polypropylene) were chosen as a matrix for comparison. The filler concentration over the cross-section of the samples was determined visually and by electronic chemical analysis. It was shown that with increasing particle size, the tendency to redistribute the concentration increases in such a way that the near-wall region becomes depleted of filler. This effect is more pronounced for high filler concentrations and for a crystallizing polymer compared to an amorphous one. [ABSTRACT FROM AUTHOR]

Polyhydroxybutyrate (PHB) is known for wide applications, biocompatibility, and degradability; however, it cannot be commercialized due to conventional recovery using solvents. The present study employed mechanical cell-disruption methods, such as Pestle and mortar, sonication, and glass bead vortexing, for solvent-free extraction of PHA from Bacillus sp. Different time intervals were set for grinding (5, 10, 15 min), sonicating (1, 3 and 5 min), and vortexing (2, 5 and 8 g glass beads with 5, 10 and 15 min each) hence studying their effect on cell lysis to release PHA. Tris buffer containing phenylmethyl sulfonyl fluoride (PMSF) (20 mM Tris–HCl, pH 8.0, 1 mM PMSF) was employed as a lysis buffer to study its action over Bacillus cells. Its presence was checked with the above methods in cell lysis. Sonicating cells for 5 min in the presence of lysis buffer achieved a maximum PHA yield of 45%. Cell lysis using lysis buffer yielded 35% PHA when vortexing with 5 g glass beads for 15 min. Grinding cells for 15 min showed a maximum yield of 34% but lacked a lysis buffer. The overall results indicated that the action of lysis buffer and physical extraction methods improved PHA yield by %. Therefore, the study sought to evaluate the feasibility of applying laboratory methods for cell disruption. These methods can showcase possible opportunities in large-scale applications. The polymer yield results were compared with standard sodium hypochlorite extraction. Confirmation of obtained polymers as polyhydroxy butyrate (PHB) was made through FTIR and 1HNMR characterization. [ABSTRACT FROM AUTHOR]

The present work investigates the effect of both surface roughness and particle morphology on the retention behaviour of granular materials via X-ray micro-computed tomography (µCT) observations. X-ray µCT images were taken on two types of spherical glass beads (i.e. smooth and rough) and two different sands (i.e. natural and roughened). Each sample was subjected to drainage and soaking paths consisting in a multiphase 'static' flow of potassium iodine (KI) brine (wetting phase) and dry air (non-wetting phase). Tomograms were obtained at different saturation states ranging from fully brine saturated to air dry conditions with 6.2 μm voxel size resolution. The data acquisition and pre-processing are here described while all data, a total of 48 tomograms, are made publicly available. The combined dataset offers new opportunities to study the influence of surface roughness and particle morphology on capillary actions as well as supporting validation of pore-scale models of multiphase flow in granular materials. [ABSTRACT FROM AUTHOR]

Silica nanoparticles (SiO2 NPs) have garnered substantial attention as versatile additives in saline fluids, finding application in areas like environmental remediation, wastewater treatment, enhanced oil recovery, and carbon geo-sequestration. Despite their potential, the intricate interaction between electrolyzed nanoparticles and porous media remains inadequately researched in these contexts. This study delves into the pivotal yet underexplored aspect of silica nanoparticle absorption behavior within porous media, a key determinant of their practical effectiveness. The research focuses on silica particles with dimensions of 10 nm and 50 nm, synthesized via hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in methanol. Employing packed glass bead columns as a surrogate for porous media, the study unravels the complex mechanisms governing nanoparticle transport and deposition. Comprehensive investigations encompass variations in particle sizes, ionic strength, and ionic species, resulting in the examination of 48 distinct flooding scenarios. UV/Vis spectrophotometry is used to quantify nanoparticle concentrations in effluents, elucidating their transport behavior within the porous media. Concurrently, pressure drop alterations across the media serve as indicators of particle plugging and changes in permeability. Intriguingly, specific conditions involving a nanofluid comprising 50 nm silica nanoparticles and 10,000 ppm of magnesium chloride exhibit pronounced permeability reduction, offering potential insights for optimizing applications. Particularly noteworthy is the unique reduction in silica particle retention on glass bead surfaces as salinity increases, especially in the presence of magnesium sulfate. A concentration of 5000 ppm magnesium sulfate induces a log-jamming mechanism, resulting in an amplified final-to-intermediate permeability ratio. Experimental outcomes align with observations from scanning electron microscopy, improving understanding of porous media retention mechanisms. This study contributes to a deeper understanding of interactions between nanoparticles and porous media, paving the way for enhanced application strategies. [ABSTRACT FROM AUTHOR]

To improve the design and scale-up processes of bubble column reactors (BCRs), it is necessary to characterize the hydrodynamics by means of flow regime behavior. This study examines the impact of industrial heat exchangers and superficial gas velocities on flow regimes, pressure drop, and gas holdup in BC and SBC. A simulated Fischer–Tropsch bubble column is constructed. The experimental study utilized a Perspex column with a diameter of 0.14 m. Moreover, 18 copper tubes with a 0.16 m diameter are fitted into the bubble column. The selection of tubes in SBC was carried out in accordance with TEMA recommendations to ensure optimal heat dissipation. These tubes were made to resemble the industrial Fischer–Tropsch reactor by covering 25% of the bubble column's cross-sectional area. In order to enhance the measurement and comprehension of the hydrodynamics within the reactor, this study employs a method measured the total gas hold-up and detected pressure fluctuations using three differential pressure transducers (Keller type PA 21Y/4). The column was equipped with a perforated plate air distributor, and glass beads were used as the solid phase. The gas distributor is constructed of porous polyethylene with pore sizes of 0.5 mm and plate thicknesses of 3 mm. To comprehend and assess the impact of tube configuration on the pressure drop; gas holdup; and regime transition velocities, the experimental data were recorded across a broad range of superficial gas velocities (i.e., 0.036–0.27 m/s). The findings suggest that higher superficial gas velocities result in amplified pressure fluctuations, with a recorded increase of 0.108 to 0.15 bar in pressure drop at a gas velocity of 0.27 m/s in the air-water system. Equipping the bubble/slurry bubble column with an industrial heat exchanger to the bubble/slurry bubble column resulted in a modest increase in pressure drop of around 0.042 bar, which disrupted the uniform flow and delayed regime transitions. Furthermore, the inclusion of solids leads to a 10% decrease in gas holdup, while the heat exchanger only slightly improves it by 5%. Drift flux analysis is a helpful tool for determining transition points. In the case of U-shaped heat exchanger tubes, the transition velocities can be altered by 1.7 m/s in BC. The results of this investigation will offer an exhaustive understanding of fluid dynamics as well as guidance in the design of reactors for extremely exothermic processes. [ABSTRACT FROM AUTHOR]

This work studied heat transfer enhancement in gas-solid fluidized beds by applying copper oxide nanocoating to glass beads. A fluidized bed column with a diameter of 10 cm and a length of 150 cm was used, A heat element placed in the center of the column at a height of 10 cm from the air distributor. The experimental methodology involves coating glass beads (200 and 400 μm) with nano copper oxide using settling deposition method, a characterization using XRD, TEM, BET, SEM, and EDX techniques for the coated beads. A fluidized bed experiment for the coated glass beads showed a significant increase in fluidized bed performance by 23% demonstrating the potential of nanocoating in improving the efficiency of fluidized bed systems for industrial applications. The research also includes conducting analysis using Minitab's Response Surface Methodology (RSM) for studying the remaining parameter on the fluidized bed performance. [ABSTRACT FROM AUTHOR]

The continued spread of Candida auris in healthcare facilities has increased the demand for widely available screening to aid in containment and inform treatment options. Current methods of detection can be unreliable and require bulky and expensive instruments to lyse and identify fungal pathogens. Here, we present a quick, low-cost, instrument-free method for lysis of C. auris suitable for streamlined sample processing with polymerase chain reaction (PCR) detection. Chemical, thermal, and bead beating lysis techniques were evaluated for lysis performance and compatibility with nucleic acid extraction and downstream PCR reactions. Using only 10 s of manual shaking with glass beads, this method demonstrated a limit of detection (LOD) of C. auris at 500 colony forming units per mL, a 20-fold improvement compared to the LOD without manual shaking, and a 60-fold reduction in time compared to common fungal lysis kits, all while maintaining repeatability and reproducibility across multiple users. This work highlights a simple method for increasing sensitivity and reducing turnaround time of PCR-based C. auris detection and exhibits promise for integration into point-of-care platforms towards real-time triage of colonized patients. [ABSTRACT FROM AUTHOR]

We use five established, but conceptually different artificial intelligence algorithms for analysing clogging and quantifying colloid transport at pore scale: artificial neural networks, decision tree, random forest, linear regression, and support vector regression. We test how these algorithm can predict clogging by interpolating physics based simulation data. Our training and test data set is based on results from Lattice Boltzmann simulations reproducing the physics of colloid transport through a typical pore throat present in glass beads or medium sized sand. We perform hyperparameter optimization through cross validation for all algorithms. The tree based methods have the highest Nash–Sutcliffe efficiencies among all tested algorithms with values mostly above 0.9 for the independent test data. The event of clogging can be predicted even with 100% accuracy. Our results indicate a non-linear, rather categorial nature of the (simulation) data. This is in contrast to the typical use of neural network algorithms for simulation data while tree based methods are often applied to observational data. We partly link this to the small size of our dataset. Our application of artificial intelligence in porous media research shows that time-consuming Lattice Boltzmann simulations can be easily supplemented and extended at small computational costs while predictability of clogging and quantitative effects of process specific parameters on colloidal transport are given with high reliability. [ABSTRACT FROM AUTHOR]

Four glass beads from a Scythian burial on the island of Khortytsia (Southern Ukraine) were subjected to 3D imaging using micro-CT and photogrammetry. The aim was to reconstruct the process used to produce and decorate the beads by detecting and interpreting the traces left by the technological processes on the bead surface and in the glass body. It turned out that all the beads were obtained by winding hot glass around the mandrel. The distribution, size and shape of the bubbles in the glass matrix revealed by the micro-CT scans and the features observed during a thorough examination of the photogrammetric models allowed us to follow the movements of the bead maker during the formation of the bead body and its decoration, highlighting several details of the production processes such as the number of the superimposed layers and the direction of the rotation of the mandrel during both the formation of the body and the decoration of the bead. Some information about the tools also emerged, with particular reference to the shape of the mandrel, the possible use of a releasing agent and how tools were used to decorate the surface or to remove the beads from the mandrel. According to the archaeological classification, the beads considered here belong to three different types, that are considered chronological indicators of the fourth century BCE and are found in archaeological sites spread over an area extending for several thousand kilometers from the Black Sea coast to the Ural Mountains. This work enriches the knowledge of the micromorphology of beads found in Eastern Europe, which is rarely discussed in the scientific literature on the archaeological glass beads. [ABSTRACT FROM AUTHOR]

In this experimental study, granular bed response to horizontal vibrations of various frequencies and amplitudes are examined with high-speed imaging. Ideal granular beds consisting of spherical glass beads are horizontally vibrated in a quasi-two-dimensional arrangement, firstly with homogeneous granular media and then with a ternary mixture to explore how bed response deviates with changes to material composition. Phenomena of note are the tendency for the homogeneous material to subdivide into discrete areas of crystalline lattice structures, bounded by non-crystalline lines of bead contacts, labelled in this paper as 'shear lines'. Shear line failure arises as neighbouring crystalline areas slide relative to one another along their shared non-crystalline border, combining to form one larger crystalline area. Under vibration conditions where particle agitation and relative movement is high, sloshing occurs in the upper bed and triangular granular-gas regions form in the top corners. The ternary mixture also exhibits sloshing at low frequency and large amplitude, but the inhomogeneity of its composition prevents formation of ordered crystalline regions and shear lines, instead promoting low percolation and a jamming effect underneath the sloshing region. Surprisingly strong convective responses are induced in the inhomogeneous bed with more energetic vibrations. From the analysis of shear lines in the homogeneous beds, and of convection in the inhomogeneous beds, comparisons between homogeneous and inhomogeneous bed behaviour are drawn. Results are used to discuss how behavioural response of non-cohesive granular material to horizontal vibrations is ultimately tied to, and changes with, the geometric complexity of the internal packing structure. The concept of 'geometric compatibility' between constituent particle species in an inhomogeneous granular medium is proposed as an explanation for the low percolation and strong convective response to vibration. [ABSTRACT FROM AUTHOR]

The lunar surface and interior are highly reducing, resulting in the virtually absence of ferric ion. However, recent studies suggest the presence of ferric iron in lunar samples, and in most cases they were found in amorphous silicates (e.g., glass beads) measured by TEM–EELS. In this work, we conducted a systematic TEM–EELS analysis on the iron valence states of Chang'e-5 impact glass beads. The Fe3+/ΣFe ratio of each silicate glass sample was determined from integral intensity of Fe L3 and L2 edge. The measurements show a positive correlation between the dwell time and Fe3+/ΣFe ratio, which reveals that ferric iron can be significantly produced by electron beam bombardment under routine analytical condition. The calculated Fe3+/ΣFe with short dwell times (≤ 20 ms) in our Chang'e-5 impact glass beads show no detectable inherent ferric iron, suggesting that the ferric iron is not ubiquitous as previously reported. It is obvious that a careful control of experiment conditions is critical to determine the inherent redox state of other beam-sensitive terrestrial and extraterrestrial samples. [ABSTRACT FROM AUTHOR]

In this work, the changes in surface roughness and thickness of particles have been investigated after coating with polymers that result in hydrophobicity after a given time period. The study fundamentally investigates the evolution of these surface properties from the instant the particles are coated. Six chemical agents have been used on near-spherical glass beads and the changes in surface profiles monitored. Surface roughness was quantified using the power spectral density method and the surface thickness of the coatings was determined by a new technique which involved calculating the change in the representative radius of asperity. Results showed that the coating process altered the surface roughness and thickness of particles irrespective of chemicals used. The time-dependency of the coating process is illustrated and it was observed that fluctuations in both surface roughness and thickness lessened after a time period of 30 min. Depending on the chemical agent used, either an overall roughening or softening was recorded at 60 min and the values of surface thickness showed increases between 71 and 256 nm. By analyzing the evolution of surface roughness and thickness at the particle level following coating, this study demonstrated the intricate link between surface properties and chemistry in inducing functional properties on particles. [ABSTRACT FROM AUTHOR]

Varroa destructor is one of the main causes of colony losses of the western honey bee (Apis mellifera). Many efforts exist to breed honey bees resistant to V. destructor. Varroa sensitive hygiene (VSH) is a commonly selected behavioural trait; VSH workers remove the pupae of mite infested brood cells with high efficiency, interrupting the reproduction of the mite. The cues and triggers for this behaviour are not yet fully understood. To determine what elicits this removal behaviour, we examined preselected VSH workers´ responses to four different groups of objects inserted into freshly capped cells: live mites, dead mites, odour reduced mites, and glass beads. These were also compared to control cells that were opened and closed without inserting any object. The pupae in cells containing inorganic objects (glass beads) were removed at similar rates to the control, demonstrating that an object alone does not trigger a removal response. Dead and odour reduced mites were removed at a higher frequency than control cells, but less frequently than live mites. Workers sometimes removed items resting near the top of the cell without removing the pupa. Our results demonstrate that although mite odour from dead mites triggers removal behaviour, the pupa of cells containing live mites were removed more frequently, suggesting that other cues (i.e. odour from feeding wound) or signals (i.e. pupal movement to signal distress) are important. Future research should focus on elucidating these other cues or signals from the brood and mites, as mite presence alone seems to be insufficient. [ABSTRACT FROM AUTHOR]

Particulate materials are utilised in many applications to manipulate the friction between surfaces. This dataset provides the characteristics of particulates used as rail sand in the train's wheel/rail interface (via an on-board system) to facilitate the train's acceleration and deceleration. Seven materials are studied including Austrian rail sand, standard Great British rail sand, waste glass beads, recycled crushed glass, non-coated alumina, coated alumina, and dolomite. The main objective of this research is to provide a physical and mechanical characterisation of these granular materials in terms of their density, bulk behaviour, particle size, particle shape, hardness, reduced modulus, and mineralogical properties. In particular, three-dimensional raw and post-processed micro-computed tomography images of more than 1200 particles are shared. The results provide a detailed dataset which can be used in ongoing and future experimental and numerical investigations studying the role of particulates in the wheel/rail interface. [ABSTRACT FROM AUTHOR]

The results of laboratory studies of the features of processes of flow through a porous medium are given for a physical model of the porous medium obtained by sintering glass beads. The program for manufacturing physical models is described and the results of the efficiency of displacement of vaseline oil by various compositions are presented. Water, mineralized water, micellar solutions, nanofluids, and micellar solutions with addition of nanoparticles were considered as the displacement agents. Based on an analysis of images, curves of variation in the saturation of the model porous medium with vaseline oil in the process of its displacement by various compositions are obtained. The micellar solutions with addition of nanoparticles were shown to be the most effective oil displacement agents in comparison with other presented compositions. [ABSTRACT FROM AUTHOR]

This paper discusses the process, prospects, and challenges of making bikini glass in Bida (Nupeland), central Nigeria. The Masagá glassmakers of Bida provide the ideal case study for investigating the production of bikini. Nineteenth-century Arab and European writings have described glassmaking in Nupeland; however, with the exception of the study carried out by Peter Robertshaw and his colleagues in 2009, there is no work that identifies the raw materials and formula used to produce bikini glass. Our recent ethnographic work at Bida provided the opportunities to collect raw glass, beads, and unfused raw material for bikini glass as well as vitrified furnace wall fragments for analysis. We present results of binocular observation and chemical compositional analysis conducted on the raw materials, glass products, and furnace remains to understand the mineralogical and chemical characteristics of various materials connected with the production of bikini. From the manufacture of glass to that of glass ornaments, bracelets, and beads, the documentation of the work of Masagá glassmakers provides new data for the history of glass and its techniques. This information is relevant for understanding glassworking in the past. The paper also addresses issues relating to migration, technology transfer, and culture contact between Nupeland and its neighbors in the Lower Niger region. It argues that the investigation of the production of bikini glass in Bida is essential for expanding our knowledge of the archaeology of glassmaking and glassworking in Sub-Saharan Africa and beyond. [ABSTRACT FROM AUTHOR]

The article focuses on the advancements in the analysis of archaeological glass using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Topics include the use of chemical analysis to determine the origin and technology of glass, the investigation of bead trade through chemistry, and the potential and limitations of analyzing glass beads.

The period between AD 700 and 1500 has been recently labeled as "Africa's global Golden Age." This is particularly true for the Shay communities living on the Muslim-Christian frontier in the ninth to fourteenth century AD. Located in the center of the Ethiopian highlands, the Shay faced the expansion of the Christian kingdoms and the advance of the Muslim polities. In an increasingly violent context of religious conversion and war between the two religious powers, the Shay stressed their independence by burying their deceased in collective structures, contrary to the mortuary practices of both Christians and Muslims, and by including precious local and global grave goods in their tombs. The laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of 34 glass beads shows how the Shay communities benefited from the Islamic global trade routes at the time, particularly the Middle East, Egypt, and the Indo-Pacific networks. This article examines the crucial role of global glass beads in the construction of a trans-corporeal landscape among the Shay that served the emergence and consolidation of the social self as a collective identity against their Christian and Muslim neighbors. [ABSTRACT FROM AUTHOR]

The fourteenth-to-sixteenth-century AD site of Songo Mnara, in the Kilwa archipelago in southern Tanzania, is a stone town with many standing coral buildings. Extensive excavations at the site have produced over 9,000 beads, 7,444 of which are glass. A subset of 140 of these was chemically analyzed using laser ablation-inductively coupled plasma-mass spectrometry, revealing a notably diverse assemblage that included four main glass types: mineral soda-high alumina (m-Na-Al), vegetable soda-high alumina (v-Na-Al), high lead glasses, and vegetable soda-lime (v-Na-Ca) glass. Here we present these types, giving the first tightly dated assemblage for the fifteenth-century coast. We then focus on two notable features of the assemblage. Among the high-lead glass beads are two types from China: one dates to the early fifteenth century and the other from about 1600. These later Chinese beads were accompanied by some of the earliest European beads (v-Na-Ca) found in eastern Africa. Their provenance and meaning are examined. Then, we discuss large folded beads that were decorated with trails of colored glass. Such beads have been recorded only at Songo Mnara and Kilwa Kisiwani, and we suggest they may have been made locally from imported v-Na-Al glass. [ABSTRACT FROM AUTHOR]

In most African contexts, glass beads are evidence of direct and indirect exchanges between communities and are often useful chronological markers. Their analysis contributes to a better understanding of the social relationships between ancient societies. Over the last decade, the archaeometric analysis of glass beads has gained ground in Sub-Saharan Africa, but large regions across southeastern Africa have remained underexplored. Glass beads excavated from the Hora 1, Hora 5, and Mazinga 1 sites in the Kasitu Valley of the Mzimba District of northern Malawi were analyzed using laser ablation—inductively coupled plasma—mass spectrometry (LA-ICP- MS). These are granitic rock shelter sites located 40 km from Lake Malawi. They have predominantly Early Holocene and Pleistocene deposits but with a scattering of more recent material at the top. Analysis revealed that most of the beads were from European manufacture with one exception—a bead that has a composition typical of South Asia and that circulated from the fifteenth to the seventeenth century AD. Although Europeans were not present in the region before the second part of the nineteenth century, the presence of European beads testifies to trade directly or indirectly involving Europeans, most likely in association with increased trade in ivory and enslaved persons. The presence of the bead from South Asia and two cowrie beads from a fourth nearby site (Kadawonda 1) that dates to the seventh century AD show that European trade was the most recent manifestation of connections between the hinterland and the coast. [ABSTRACT FROM AUTHOR]

The study of the Palaeolithic in Senegal has made considerable progress in the last decade and has provided a renewed vision of the behavioral evolution of prehistoric populations in West Africa. The cultural trajectories within the region seem to be highly variable and bear witness to strong behavioral dynamics, the mechanisms of which still need to be better understood. However, the number of reliable, dated, and stratified sites, as well as the palaeoenvironmental data providing a context for populations in their palaeolandscapes, is still scarce. In order to provide new and solid data, we conducted new archaeological survey in the Niokolo-Koba National Park in south-central Senegal, aiming at a preliminary identification of Pleistocene and early Holocene sedimentary deposits. Here, we report an overview of the newly discovered industries found in different contexts. Most of the 27 identified sites show surface and out-of-context assemblages, but other sites are stratified and have all the criteria to justify the development of a long-term archaeological, geochronological, geomorphological, and palaeobotanical project. The Niokolo-Koba National Park, through which the Gambia River flows, is characterized by an abundance of sources of knappable material and by well-preserved sedimentary sequences. Therefore, archaeological research in the Niokolo-Koba National Park has the potential to provide major milestones in our understanding of the evolutionary dynamics at work in West Africa during the early periods of occupation of the region. [ABSTRACT FROM AUTHOR]

International expeditions extensively excavated Lower Nubia (between the First and Second Nile Cataracts) before it was submerged under the waters of Lake Nasser and Lake Nubia. The expeditions concentrated on monumental architecture and cemeteries, including sites at Qustul and Serra East, where the New Kingdom, and Napatan, Meroitic, Nobadian, and Makurian-period elites and common people were buried, ca. 1400 BC–AD 1400. Although the finds abound in adornments, including bead imports from Egypt and South India/Sri Lanka, only a few traces of local glass bead-making have been recorded in Nubia so far. Based on results of laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analysis of 76 glass beads, pendants, and chunks from Qustul and Serra East contexts, dated between the New Kingdom and the Makuria Kingdom periods, this paper discusses the composition and provenance of two types of plant-ash soda-lime (v-Na-Ca) glass, two types of mineral soda-lime glass (m-Na-Ca), and two types of mineral-soda-high alumina (m-Na-Al) glass. It also presents the remains of a probable local glass bead-making workshop dated to the period of intensive long-distance bead trade in Northeast Africa, AD 400–600. [ABSTRACT FROM AUTHOR]

This article presents the discovery and analysis of a new glass bead assemblage from the Swahili site of Mkokotoni, an early second millennium AD settlement in northwestern Zanzibar. It explores the possibilities for local production of glass beads using imported glass cullet or glass tubes at this site. Glass beads are ubiquitous at archaeological sites from the second millennium on the East African coast. They are presumed to have been traded via long-distance networks from South and Southeast Asia, and used locally in personal adornment, barter, and ritual practices. However, the data from Mkokotoni offers a new and unique perspective on glass bead-making traditions, which places the East African coast as an area of production and distribution. [ABSTRACT FROM AUTHOR]

Several types of (mostly) blue-green glass beads from Iron-Age archaeological sites in Central Italy were studied using a range of spectroscopic techniques: portable X-Ray Fluorescence spectrometry, Fibre Optics Reflectance Spectroscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectrometry, micro-Raman spectroscopy and Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Complementary information was gathered from each technique and discussed in the frame of the archaeological typology of the objects. The systematic evaluation of the results allowed us to draw some conclusions on the raw materials employed for primary production and to highlight some provenance indicators in the glass. Some of the beads found in the Iron Age (IA) contexts were preliminarily attributed to the Final Bronze Age (FBA) production based on their typology, and the compositional data obtained in this work confirmed that they were low magnesium high potassium (LMHK) glass, typical of FBA in the Italian peninsula. Other beads were assigned to low magnesium glass (LMG) or high magnesium glass (HMG), thus giving further information on the fluxing agents employed in the Early Iron Age (EIA) and beyond. Colour variations among the beads reflected their chemical composition, with different bead typologies coloured in a specific way. In some instances, it was possible to establish different origins for the colouring raw materials. The provenance of the samples was difficult to place, but the chemical evidence suggested a subdivision within the raw glass used to produce the beads: for one set of samples, a local origin of the glass could be hypothesised, whereas several production sites in the Near East were suggested for most of the beads considered in this study. Some preliminary clues for the local working of imported glass were also highlighted for one typological group. [ABSTRACT FROM AUTHOR]

The long time period covered by the Hostivice cemeteries of the fourth century, late fifth–mid-sixth centuries and tenth century makes it possible to study the development of glass beads from the Late Roman period to the Early Middle Ages. Chemical analyses confirmed that the beads from central Europe reflect the principal transition from natron to plant ash glass during the eighth–ninth centuries. This study also shows that the beads made from natron glass were still distributed in the ninth–tenth centuries when new types of beads were made from this glass. Some of these beads are products of central European glass-working, where they occur alongside imported beads. Apart from that, high-boron glass, high-lead glass and a faience bead were also present at Hostivice in the tenth century. Limitations of chemical analysis in the study of beads related to compositional subgroups of natron glass and connected with the large scale of recycling and to the heterogeneity of opaque glass of beads are discussed. The recognition of supraregional and local types of beads, together with the synthesis of chemical and archaeological data, allowed us to characterize the reciprocal relations between chemical groups of glass and the typology and manufacturing techniques of the beads. [ABSTRACT FROM AUTHOR]

Understanding the impact and penetration characteristics of non-homogeneous granular material systems is of great significance for various research work. In this study, a series of experiments are conducted to investigate the impact and penetration processes of sand and glass beads, two granular materials with different moisture contents. The ultra-high-speed camera is used to capture the dynamic response of the projectile, while the impact force during impact and penetration is recorded by miniature load cells arranged underneath the container. The results show that the dynamic response of the projectile differs significantly for different types of granular materials with different moisture contents. The comparison between wet and dry granular materials reveals that the terminal penetration depth and the duration of the collision are much less for wet granular materials than for dry ones, and the effect of moisture content on the terminal penetration depth of the projectile is discussed. Assuming that the presence of moisture has no effect on the inertial force term, a modified motion equation is proposed taking into account the suction of wet granular materials. [ABSTRACT FROM AUTHOR]

Purpose: The laser diffraction method has become increasingly popular during the last decades to measure the grain size distribution of various environmental particles originating from sediments, soils or river suspended sediments. However, the measurement of multimodal samples containing sands is still an issue. The aim of this study is to discuss the limits of the laser diffraction method in measuring the sand fraction of bimodal samples. Materials and methods: A systematic comparison of four commercially available laser diffraction instruments (Cilas 1190L, Fritsch Analysette 22 Nanotec, Malvern Mastersizer 3000, and Sequoia Lisst 200X) is performed on 12 unimodal and bimodal samples of glass beads and silica-rich natural sands. Results: Measured grain size distributions differ between the four instruments. Most important differences occur in bimodal samples containing a sand fraction, where some instruments have major difficulties to estimate the proportion of the fine towards coarse mode correctly, with errors up to 100%. Conclusion: In accordance with the observation of coarse particles accumulating in low-velocity areas within the sampling tank, the creation of an imperfect suspension within the sampling tank is considered as a main reason for the differences. The choice of the most suitable measurement parameters is crucial to obtain accurate and precise measurements. However, these parameters cannot be compared between the instruments, nor exist precise user guidelines. Therefore, testing several measurement parameters before analyzing novel sample compositions using laser diffraction is recommended. [ABSTRACT FROM AUTHOR]

For the first time, copper oxide–coated glass beads (CuO-GBs) were fabricated using physical vapor deposition (PVD) technology for sequestrating Pb2+ ions from solution is addressed. Compared to other coating procedures, PVD offered high-stability uniform CuO nano-layers attached with 3.0-mm glass beads. Heating of copper oxide–coated glass beads after deposition was rather necessary to achieve the best stability of the nano-adsorbent. Detection of nano-size copper oxide on the beads was made by FTIR (intense peak at 655 cm−1 for CuO bond stretching) and XRF (Cu peak at 8.0 keV). Scanning electron micrographs taken at high magnification power indicated the presence of CuO in nano-range deposited over glass beads. The maximum deposited amount of CuO on the beads was 1.1% and accomplished at the following operational conditions: internal pressure 10–5 mmHg, Ar flow rate 8.0 mL/min, voltage 84 V, pre-sputtering time 20 s, total sputtering time 10.0 min, and post-heating temperature 150 °C for 3 h. A univariate analysis indicated that the optimum Pb2+ uptake by CuO-GBs from solution was achieved at pH 7.0–8.0, 7 beads/50 mL, 120-min contact time, and 15-mg/L initial concentration. Kinetic data for Pb2+ uptake was best presented by a pseudo–second-order model with a relative prediction error of 3.2 and 5.1% for GBs and CuO-GBs, respectively. On the other hand, Pb2+ equilibrium isotherms at 25 °C were fairly presented by the Langmuir model, and the predicted saturation values were 5.48 and 15.69 mg/g for GBs and CuO-GBs, respectively. CuO and CuO-GBs had similar Pb2+ saturation values (~ 16 mg/g), although the latter demonstrated 4 times faster kinetic, thanks to fixation CuO on glass beads. Moreover, the chemical stability of copper oxide–coated glass beads was tested under different conditions. Recycling of copper oxide–coated glass beads was also investigated, and 90% of the surface was recovered using 0.01-M HNO3. [ABSTRACT FROM AUTHOR]

The abrasive and rock properties have a significant impact on the performance and profitability of abrasive water jet (AWJ) cutting. In the relevant literature, there is no comprehensive study that investigates the effects of abrasive type on the AWJ cutting of rocks. As a result, in the current study, various abrasives (garnet, white fused alumina, brown fused alumina, glass beads, emery powder, olivine, steel shot, and plastic granule) were used in tests where workpieces prepared from various rock types (igneous, metamorphic, and sedimentary) were cut with AWJ. The cutting parameters were kept constant during the cutting operations. The cutting depth was taken into account when evaluating the AWJ performance. It was revealed that garnet, steel shot, and fused alumina (brown and white) have higher cutting abilities (cutting depth: 39.23–125.94 mm by the rock type). Compared to them, olivine, emery powder, and glass bead produced shallower cuts (21.11–80.00 mm by the rock type). Despite this, effective cutting did not occur with plastic granules. It was demonstrated that there are strong correlations between the cutting depth-abrasive hardness (up to r: 0.82 by rock type) and cutting depth-abrasive density (up to r: 0.87 by rock type). It was determined that the cutting depth increases as the Bohme abrasion loss, effective porosity, and water absorption capacity of the rocks increase. It was also found that the cutting depth decreases as the strength, Schmidt hardness, unit volume weight, and ultrasonic wave velocity of the rocks increase. The most essential rock properties influencing cutting depth were determined as the Bohme abrasion loss, uniaxial compressive strength, and point load strength. [ABSTRACT FROM AUTHOR]

The distribution of olive and fusiform beads, geographically limited to Bohemia, Moravia (Czech Republic), Bavaria (Germany) and its surrounding area in the eighth–tenth centuries, suggests local central European glass-working. Archaeological differences in regional preference for olive or fusiform beads, typological details and their not entirely synchronous occurrence point to their production in several workshops. LA-ICP-MS analyses of 76 beads show that most of the beads were made from recycled soda-lime-silica natron glass of the older Roman tradition and Late Antique tradition, including Roman Mn, Mn-Sb, HIMT and Foy 2.1/2.2 subgroups, and contemporary glass from Egypt (so-called Egypt 2). Only isolated finds of olive beads from Bohemia were made from Islamic plant ash and western European wood ash glass. The reuse of glasses of different opacity and multiple colours was investigated by SEM-EDS on four beads. The present paper raises the question of glass sources for local glass-working in central Europe and contributes to the study of reuse and recycling of glass in this part of Europe. [ABSTRACT FROM AUTHOR]