Loose Powder Research Articles

Effect of experimental parameters on X-ray Micro-CT imaging for Spectral CT applications

Computed tomography (CT) is recognized as a reliable method for structural characterization of different materials. Recently, Spectral CT methods have emerged as a tool to describe the sample composition through assessment of mass density (ρ) and effective atomic number (Zeff) assessment from CT results. These techniques depend on measuring the linear attenuation of a set of standards samples. However, besides ρ and Zeff, these results are influenced by factors such as X-ray energy and may be affected by experimental factors not accounted for in the foundational equation. Thus, in this study, we propose to quantify the effects of two factors: uniaxial compression and image pixel size on measurements of linear attenuation assessed through the registered mean gray value and its standard deviation. Initially, a group of metallic oxides pellets were compressed under different pressures and scanned at various magnification factors. Subsequently, based on factorial design theory, Yates’ method was applied to evaluate the significant effects of the factors. In a second phase, using a group of known samples, a Dual-Energy CT (DECT) measurement of a validation sample was conducted to verify the quantified effects. As expected initially, we observed that uniaxial compression positively influences attenuation, as it directly affects mass density. However, we found that an increase in image pixel size leads to a decrease in registered attenuation as it reduces the relationship between radiation attenuation and detected photons. Indeed, for the leveraged variation, the linear effect of pixel size variation proved to be the most influential on the registered mean gray value. When considering these effects in DECT application, no statistical difference was observed between loose powder and pellet measurements. Furthermore, no trend was observed in the results regarding image pixel size. However, it is possible that more significant changes in these factors may yield different results, and therefore, operators applying Spectral CT methods must ensure that the same experimental conditions are applied to both the standard sample set and the sample under investigation.

Exploring the Photophysical and Mechanical Behavior of Fluorescent Metal-Organic Framework Monoliths.

Luminescent metal-organic frameworks exhibit great potential as materials for nanophotonic applications because of their programmable properties and tunable structures. In particular, luminescent guests (LG) can be hosted by metal-organic frameworks due to their porosity and guest confinement capacity, forming LG@MOF composite systems. However, such guest-host systems are mainly produced as loose powders, preventing their widespread use in practical devices and technological applications that require implementation of a stable continuum solid. In this regard, using monolithic MOF hosts might be a workable option to solve this challenge. Herein, we reported the facile synthesis and fabrication of novel prototypical sol-gel monolithic systems, designated as LG@monoMOF. Red (rhodamine B), blue (7-methoxycoumarin), and yellow (fluorescein) emitting dyes were encapsulated in a robust UiO-66 monolithic host, resulting in the red, blue, and yellow light-emitting luminescent monoliths. The mechanical and photophysical characterization of the three LG@monoMOF systems was systematically carried out in order to unravel the role of guest-host interactions in the mechanical and optical response of the bespoke LG@monoMOF composites.

Physicochemical Methods for the Structuring and Assembly of MOF Crystals.

ConspectusMetal-organic frameworks (MOFs) are promising for various applications through the creation of innovative materials and assemblies. This potential stems from their modular nature, as diverse metal ions and organic linkers can be combined to produce MOFs with unique chemical properties and lattice structures. Following extensive research on the design and postsynthetic chemical modification of MOF lattices at the molecular level, increasing attention is now focused on the next hierarchical level: controlling the morphology of MOF crystals and their subsequent assembly and positioning to create functional composites.Beyond well-established methods to regulate crystal size and shape through nucleation and coordination modulation, physicochemical techniques leveraging wetting effects, interparticle interactions, and magnetic or electric fields offer attractive avenues for the hierarchical structuring and assembly of MOFs. These techniques facilitate crystal alignment and yield unique superstructures. While our research group primarily focuses on directing MOF crystal orientation and positioning using external stimuli such as magnetic and electric fields, we also explore hierarchical MOF synthesis and structuring using liquid interfaces and depletion force-assisted packing.This account highlights our journey and progress in developing methods to regulate the morphology, assembly, orientation, and positioning of MOF crystals, placed in the context of work by other groups. First, we examine commonly utilized structuring methods for MOF crystals that employ liquid-liquid and air-liquid interfaces to spatially confine reactions, allowing us to access unique morphologies such as mushroom-like crystals and Janus particles. We also discuss strategies for concentrating and packing MOF crystals into superstructures, utilizing fluid interfaces for spatial confinement of crystals, depletion forces, entropic effects, and crystal sedimentation.A particularly compelling challenge in expanding the applicability of MOF materials is how to manipulate free-standing MOF crystals. This issue is especially important because MOFs are typically produced as loose powders, and industrial material processing is generally more efficient when the material is fluidized. While extensive research has been conducted regarding MOF growth on substrates with both positional and orientational control, there is a clear need for similar precision with free-standing MOFs dispersed in a fluid matrix. Our group has thus focused on the relatively new, yet powerful approach of using electric and magnetic fields to manipulate MOF crystals, which offers unprecedented control over the orientation and positioning of dispersed MOF crystals, complementing the more well-established methods of MOF growth on substrates. In this Account, we provide foundational background and discussions on the interactions between these external fields and MOF crystals, including critical considerations for effective MOF manipulation using such techniques. We also discuss their unique advantages and applications, and briefly examine potential application areas, such as photonics, smart materials like soft robotics and absorbents, and sensing. This Account highlights the promising potential of well-organized and aligned MOF crystals over randomly oriented ones in various applications, owing to enhanced selectivity and performance. It underscores the importance of specialized assembly methods to advance materials science and engineering, encouraging the reader to explore such approaches.

Large-Scale Analysis on Accelerated Aging of Pentaerythritol Tetranitrate (PETN) Powders in Detonators.

Pentaerythritol tetranitrate (PETN) has been used extensively in commercial detonators and other explosive applications for many decades. Here, we show the results of a comprehensive 1.5 year aging study of PETN in commercial detonators, addressing batch-to-batch variations, surface area changes, and comparisons of aged loose powders side-by-side with identically aged detonators. Function time analysis of the aged detonators has also been provided and discussed in the context of powder aging. This large-scale, statistically relevant study addresses long-standing questions on PETN aging without the complications from making comparisons between multiple batches of material. We have evaluated the aging time required to reach the maximum measured amount of PETN coarsening and estimated an activation barrier of ∼123 kJ mol-1, which is higher than literature values reported by Gee et al. It is possible that this discrepancy is due to the fact that that this study cannot quantify the relative contributions of surface diffusion versus sublimation processes. At the lower temperatures of 50 and 60 °C, we assume that surface diffusion dominates over sublimation processes, even at longer aging times. At the higher temperature of 75 °C, we assume that both surface diffusion and sublimation contribute at the early time points, which are included in the Arrhenius analysis for coarsening.

AB5-based metal hydride embedded in polyethylene and polymethylmethacrylate for hydrogen storage

Loose powder in metal hydride reactors poses challenges, such as poor thermal conductivity and tube deformation. To address these issues, the metal powder can be encapsulated in a polymer-based matrix to form pellets. This encapsulation helps make the pellets oxygen-impermeable, capable of accommodating the volumetric expansion of metal hydrides, and increases system processability. This study investigates the use of polymer-based pellets containing AB5-based compounds for ambient hydrogen storage. Polymers were selected using ANSYS Granta software, and polyethylene and polymethylmethacrylate were chosen. The AB5 alloy activation in the pellet occurs efficiently after 3 min at 20 °C and 30 bar of hydrogen, facilitated by ball milling-induced reactive surfaces and increased grain boundaries. The optimized pellet, comprising 90 wt% AB5 powder in a PE matrix, exhibits stable hydrogen storage properties, with good mechanical resistance and minimal powder loss (below 3%) over 20 hydrogen sorption cycles in an in-house fabricated single-tube metal hydride reactor.

Determination of Airborne Release Fractions from Loose Powder Contamination Under Impact Stress

Safety basis calculations support the safety considerations necessary for legacy nuclear facilities as they transition from active use, through limited operations and standby modes, until final disposition is achieved. Many of the calculations are governed heavily by the coefficients presented in DOE-HDBK-3010 in the form of airborne release of radioactive material resulting from penetration of the facility per seismic activity, full facility fires, and/or explosions. The main objective of this study is to validate the original data for airborne release fractions (ARFs) for powder contaminants under impact, as determined in DOE-HDBK-3010. The limited data available for impact experiments was generated at the Rocky Flats Plant in 1987, where the median ARFs for surrogate powder contamination were 4E-4 with a bounding value of 1E-2. However, estimating the level of uncertainty was challenging in the absence of multiple measurements conducted under identical test conditions. Moreover, the uncertainty was significantly increased due to the restricted range of the test conditions. A more modern approach has been developed for the experimental design in this study, utilizing standardized techniques and analytical instruments. An impact apparatus was employed to be able deliver repeatable impact forces up to 369 kg·cm (320 in.·lb.). Cesium chloride was used as the surrogate powder contaminant in these experiments as it is extremely soluble in water and is even more so in the acidic media used to leach/dissolve the air filters for concentration analysis using mass spectrometry The developed approach leveraged multiple international standards and historical documents in an attempt to recreate a valid testing system that can be used for future analysis and to analyze mitigation factors such as contamination fixative technologies. The current ARFs were found to be consistent with the original values in DOE-HDBK-3010, 3.47E-4 and 4E-4, respectively.

Material incorporation in powder sheet additive manufacturing toward lightweight designs for future mobility

Additive manufacturing of AlSi10Mg has obtained increased attention due to its lightweight feature. However, handling of loose powder, efficient usage of feedstock, and powder recycling still remain major open challenges. Herein, a novel additive manufacturing method based on metal additive manufacturing using powder sheet (MAPS) is proposed, which leverages composite flexible films made of the feedstock of metal powder and a polymeric binder, aiming to extend the range of applicability of AlSi10Mg-based additive manufacturing technologies, for example, vehicle components. In situ high-speed imaging is used to explore the underlying manufacturing mechanisms of the proposed MAPS concept and investigate the laser–powder sheet interaction. In addition, a representative computational thermo-mechanical model was used to evaluate the substrate deformation due to the printing process, a critical aspect that must be minimized in order to transfer this technology to larger scale applications.

Optimal design and simulation investigation for high-density hydrogen storage tanks filled with rare earth-based (RE-Ca)(Ni-Co)5 optimized alloy

The slow kinetic rate due to strong thermal effect limits the practical application of metal hydride tanks in high-density hydrogen storage. In this work, we concentrate on a comprehensive experimental and numerical investigation of metal hydride beds with rare earth-based (RE-Ca)(Ni-Co)5 optimized alloy to explore faster reaction rates. Two different cylindrical tanks were manufactured to reflect de-/hydrogenation characteristics. A study on the temperature evolution in the loose powder bed was performed first, followed by five other different bed configurations: alternated powder layers with Al fiber layers, powder mixed with Al fibers, compacted discs (mixture of powder, resin and graphite), alternated compacts with Al fins and alternated Al foil-wrapped compacts with Al fins. Among them, the compacts provide good heat transfer capacity, with additional Al foils and fins for optimum thermal diffusion, reducing the reaction time by almost 50 %. Stress concentrations caused by powder accumulation can also be avoided thanks to the stable structure. Finally, the numerical model was adapted to simulate the de-/hydrogenation processes of the optimized bed and the experimental data matched well with the computational results, confirming the reliability of the model. It lays the foundation for the design and operation optimization of high-density hydrogen storage in the future.

Waste silica sand as a possible pozzolanic filler to produce cement mortars: experimental investigation

The present paper discusses experimental results obtained on several mortars prepared using a commercial type1 OPC cement, a commercial limestone aggregate with maximum particles dimension below 5 mm, superplasticizer and water. Different amounts of a waste silica sand, in form of loose powder, derived from the industrial production of refractory blocks, were added to the above basic components. Several additional samples were also prepared using same basic commercial components added by different amounts of a fine limestone filler. This latter set of compositions was used to prepare samples to be used as reference materials. Waste silica sand and fine limestone filler were used as received from their producer. During preparation, pastes containing silica sand showed better workability compared to all the other blended components. All hydrated materials displayed fair compressive strength and low water absorption after curing, but those containing silica sand showed the best mechanical performances due to their low residual porosity and to the pozzolanic reaction which could enable application for the production of structures in direct contact with water or aggressive environments such as sewers or tanks suitable for the containment of organic substances.

Development of Assessment Instruments to Measure Scientific Performance

This research aims to develop a scientific performance assessment instrument in the laboratory in experiment of analyzing the content of a compound in loose powder. The assessment instrument developed is in the form of worksheets and performance assessment sheets and rubrics. The method used in this research is design-based research (DBR) with two stages, namely the analysis stage and product design development. Data collection was carried out by validation tests to expert lecturers and the results were analyzed. The results of the validation test of scientific performance assessment instruments in the form of worksheets obtained a value of rcount = 0.83 and performance assessment sheets rcount = 0.84. This value indicates that both instruments are valid.
 Keywords: development, assessment instruments, science performance

Effect of Copper Content on the Microstructure and Properties of the Sintered Porous Aluminum Wick

Porous aluminum has been widely used as a wick, an electrode, and in other products, due to its advantages of a light weight, pore uniformity, and corrosion resistance. However, the dense alumina layer on the surface of Al powder hinders its densification during sintering. In this paper, porous aluminum was prepared via loose powder sintering with the addition of Cu as a sintering aid. The effects of Cu content on the microstructure and wick properties of the porous aluminum were investigated. The results showed that, with increasing Cu content, the porosity and capillary properties of porous Al decreased, while the compressive strength improved. The optimal Cu content was determined to be 3 wt.% and the prepared porous Al has a porosity of 47.5%, plateau stress of 11.82 MPa, and capillary characteristic parameter of 6.72 × 10−8 N, meeting the requirements for wicks in heat pipes. These findings contribute to the demand for the lightweight design of heat pipes for aerospace applications.

Critical evaluation of energy dispersive X-ray fluorescence spectrometry for multielemental analysis of coffee samples: Sample preparation, quantification and chemometric approaches

In the present contribution, a critical evaluation of the use of EDXRF (Energy dispersive X-ray fluorescence spectrometry) for elemental composition determination (K, Ca, Mn, Fe, Cu, Zn, Sr and Rb) of coffee samples is presented. Firstly, several sample treatment procedures (pressed pellets and loose powder) and quantification strategies (fundamental parameters and empirical calibration) were evaluated.In addition to quality and nutritional purposes, information of elemental content in coffee samples can be also useful for coffee traceability and provenance studies. In view of that, a comparison of different tools such as explorative principal component analysis (PCA) and classification by partial least square regression (PLS-DA) were also tested as discriminating tools of different types of coffee samples (i.e., pure, instant and coffee with additives). Chemometric analysis was performed using coffee elemental concentrations determined by the developed EDXRF method and, for the first time, using raw EDXRF spectra obtained, without the need of a fitting and quantification procedure.

Gas Permeable Protection Caps for Wafer Level Chip Scale Packaging (WLCSP) of MEMS Environmental Sensors

This work presents new porous environmental protection caps designed for wafer level chip scale packaging (WLCSP) of MEMS environmental sensors. The caps consist of gaspermeable microstructures formed from loose aluminum oxide powder solidified by a ceramic thin film, grown using atomic layer deposition (ALD). For the first time, the full process flow of the proposed approach is demonstrated by manufacture of the cap wafer followed by substrate bonding using glass-frit technology. By analyzing the influence of the caps on the response time of MEMS humidity sensors, this study proves the viability of the proposed packaging technology. In addition, the ability to further functionalize the porous caps is demonstrated by the deposition of a superhydrophobic polymer thin film by chemical vapor deposition.

The relationship between the use of cosmetics and the occurrence of acne vulgaris in female medical students at the faculty of medicine UKI in the year 2016

Acne vulgaris is a chronic inflammation of the pilosebaceous follicles caused by various factors, typically characterized by distinctive clinical features and usually occurring in adolescents and young adults. The use of cosmetics can lead to the development of acne in women, as the ingredients used may be comedogenic or acnegenic. The current use of cosmetics is undeniably an essential need for women. The aim of this study is to determine the relationship between the use of different types of cosmetics and the occurrence of AV. The variables examined in this research include compact powder, loose powder, sunblock, foundation, and blush. This study is an observational research with a cross-sectional design involving a sample of 100 female medical students from the Faculty of Medicine at the Christian University of Indonesia, divided into two respondent groups: one with acne and one without acne. The chi-square test is used for the analysis. From the research results, it can be concluded that, of the five variables studied, only the use of compact powder showed a significant correlation.

Coupling direct powder deposition with spark plasma sintering: a new approach towards rapid prototyping

In this paper, we propose a modified material jetting technology based on a piezoelectric-driven powder deposition, hence direct powder deposition (DPD), combined with pressure-assisted rapid sintering. This is a new approach toward the rapid production of metal and ceramic materials with complex geometries. The combined deposition of two loose powders within the same container, layer by layer, allows realizing complex shapes without the use of any binder or dispersing medium. The resulting green sample is then sintered by field assisted sintering (FAST) or spark plasma sintering (SPS) operating in a pseudo-isostatic mode. This combination of DPD and FAST/SPS allows great versatility, as it can be extended to a wide range of materials and composites without any significant modification of the setup. Moreover, the use of FAST/SPS densification allows the realization of fully sintered samples in less than one hour.

The Evaluation of Loose Powder Formulation of Manihot Starch and Maydis Starch with Natural Orange Sweet Potato

The Evaluation of Loose Powder Formulation of Manihot Starch and Maydis Starch with Natural Orange Sweet Potato

Loose and Encased Graphite for Methylene Blue Adsorption: Process Optimization and Principal Component Analysis

AbstractGraphite is often converted to expanded graphite or graphene for water remediation. However, these processes require extra chemicals and energy. This study tested loose and encased pristine graphite powders for dye removal. The loose graphite exhibited good methylene blue removal (>97 % across pH levels), indicating that π‐π interaction is the governing factor besides electrostatic attraction. Notably, 5 g of loose graphite led to 100 % removal. Langmuir isotherm fitting disclosed a maximum adsorption capacity of 4.7059 mg g−1. Principal component analysis showed that dye concentration and adsorbent dosage had a greater impact than pH and contact time. However, encasing graphite in a tea bag inhibits adsorption; future studies could explore options facilitating adsorbate penetration into tea bags.

Microstructural evolution and intermetallic formation in Zn-3Mg (wt%) powder mixture processed by high-pressure torsion

Severe plastic deformation (SPD) techniques have been used extensively over the past 40 years for producing strong metals and alloys. High-pressure torsion (HPT) is one of the most promising SPD techniques for achieving high strength through nanoscale grain refinement and phase transformation. In this research, a mixture of pure zinc (Zn) and magnesium (Mg) powders, Zn-3Mg (wt%), was HPT-processed under a pressure of 6 GPa for 1, 5, 10, 20, and 30 turns at room temperature to achieve a high strength biodegradable material. In order to understand the effects of pre-consolidation on the resulting microstructure and hardness, HPT processing was performed on loose powders placed in the die and also on a pre-compacted powder mixture and the resulting HPT disks were characterized by X-ray diffraction, scanning electron microscopy, atom probe tomography, and Vickers microhardness. In both cases, the HPT disk microstructures contained nanoscale grains, and stable and metastable strain-induced intermetallics, but an unusual softening appeared at large shear strains. Grain size, grain morphology, and the formation of different intermetallics were analyzed to explain the unusual hardness distribution, and it was found that an inverse Hall-Petch relationship between hardness and grain size exists. It is suggested that thermally-activated phenomena such as grain boundary sliding contributed to the strain-induced softening of this nano-structured biomaterial due to its low melting point. The current results are compared with those for HPT-processed cast alloys and hybrids of the same composition.

Estetika Tari Sambut Telu Muli Cindo Dari Ogan Komering Ulu Selatan

The aesthetics of the welcome telu muli cindo dance in south Ogan Komering Ulu district, this study aims to express: 1) The integrity of the sambut telu muli cindo dance in south Ogan Komering ulu district, namely (a) The movements are graceful and the dancers are graceful. (b) The floor pattern used is one line, then a triangle, then an oblique line.(c) Musical accompaniment used is more dominant to a single guitar musical instruments (d) the costumes used by the dancers are woven fabrics typical of the south Ogan Komering Ulu region, namely kawai towels and red velvet clothes typical of palembang (e) The makeup used is tools (Foundation, Eye shadow, lip cream, loose powder, pressed powder, counter, concealer, blush on, mascara, eyebrow pencil, and false eyelashes) (f) accessories used are banyan heads, swings, gandik,cempako flowers, crowns, and buns.
 Keywords: Dance aesthetics welcome telu muli cindi dance

Metals Contained in Various Formulations of Mineral Nitrogen Fertilizers Determined Using Portable X-ray Fluorescence

According to the Scopus database, over the last five years, 91 scientific papers with the keyword “pXRF” (portable X-ray fluorescence) were published in indexed journals in the domain of environmental science and agricultural science, which indicates more frequent applications of this technique in scientific research. The pXRF method is characterized by speed, precision, accuracy, and the possibility of a simultaneous analysis of a large number of elements, albeit with higher limits of detection (LODs) as a major disadvantage. The presence of metals in certain phosphate fertilizers is well established, though not to the same extent as in mineral nitrogen fertilizers. The aim of this research was to determine the metal content (As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Si, Sr, Th, U, Zn, Zr, and Y) in thirteen commercial mineral nitrogen fertilizers via the pXRF method. Six straight fertilizers (ammonium nitrate, ammonium sulphate nitrate, limestone ammonium, nitrate, and urea) and seven complex fertilizers (various NPK formulations), which are different even according to their production technology, produced in Croatia were analyzed using the handheld Vanta C (Olympus) XRF analyzer according to the loose powder method and “point and shoot” technique. Data quality control was performed by analyzing the reference fertilizer samples and certified and reference soil samples. The results revealed that the determined contents of Cd, Mn, and Th were relatively higher in the single-component fertilizers, while the contents of As, Cr, Fe, Ni, Si, Sr, Zn, Zr, Y, and U were relatively higher in the complex fertilizers. Due to the higher LODs of Co and Pb (3 mg/kg) and Mo (2 mg/kg), the pXRF method was not appropriate for the determination of these metals in the analyzed fertilizers. The quantified metal content in the analyzed fertilizers varied as follows: 2.0–8.0 mg As/kg; 11.5–31.3 mg Cd/kg; 29.8–118.5 mg Cr/kg; 7.8–26.3 mg Cu/kg; 16.5–2209 mg Fe/kg; 20.3–5290 mg Mn/kg; 6.2–27.8 mg Ni/kg; 1156–4581 mg Si/kg; 2.0–469.8 mg Sr/kg; 3.0–35.3 mg Th/kg; 2.0–82.8 mg U/kg; 1.4–166 mg Zn/kg; 9.7–15.3 mg Zr/kg; and 16.5–128.0 mg Y/kg. The results indicated that the pXRF method is particularly suitable for measurement and metal detection in complex nitrogen mineral fertilizers with higher amounts of metals, but it is not suitable for the detection and quantification of the lower amounts of As, Zr, Y, Cu, Ni, and Cr in single-component nitrogen fertilizers. Compared to all of the investigated fertilizers, the highest amounts of As, Cr, Cu, Fe, Ni, U, Zn, and Zr were quantified in the NPK 7-20-30 formulation.