Metal Pellets Research Articles

Actual approaches to the transportation of biological samples at low temperatures.

Taking into account the impact of shipment method of biosamples is necessary for obtaining high-quality biological samples in biobanking and laboratory research. The impact of liquid nitrogen, dry ice and cold accumulators on the quality of biological markers was considered, as well as recommendations to reduce the impact of these methods of shipment. The liquid nitrogen provides the best preservation of samples, however, dry ice is used much more often during their transportation. When transporting certain types of cells using dry ice, there is the way to use CryoStor CS1 and Cell Banker 1 cryoprotectors. The dry ice has a significant effect on both the pH of liquid biological samples and the coagulological parameters of plasma samples. The penetration of CO2 into the sample leads to changes in the parameters of PTT and APPT, as well as to decrease the protein C and fibrinogen level under certain conditions. Serum and plasma samples exposed to dry ice for more than 16 hours should be thawed open at room temperature, or instead of it should be kept at -80 °C for 24 hours to avoid changes in coagulation parameters, The use of cold accumulators is unacceptable for long-term shipment of serum and plasma containing unstable biomarkers because of insufficiently low temperature (increase over time to -25 °C and above). Besides, metal pellets can be used as cold storage batteries at low temperatures (up to -80 ° C), but they are not as effective as dry ice, since it is able to hold the required temperature for much longer.

Epitaxial growth and superconducting properties of thin-film PdFe/VN and VN/PdFe bilayers on MgO(001) substrates.

Single-layer vanadium nitride (VN) and bilayer Pd0.96Fe0.04/VN and VN/Pd0.92Fe0.08 thin-film heterostructures for possible spintronics applications were synthesized on (001)-oriented single-crystalline magnesium oxide (MgO) substrates utilizing a four-chamber ultrahigh vacuum deposition and analysis system. The VN layers were reactively magnetron sputtered from a metallic vanadium target in Ar/N2 plasma, while the Pd1−xFex layers were deposited by co-evaporation of metallic Pd and Fe pellets from calibrated effusion cells in a molecular beam epitaxy chamber. The VN stoichiometry and Pd1−xFex composition were controlled by X-ray photoelectron spectroscopy. In situ low-energy electron diffraction and ex situ X-ray diffraction show that the 30 nm thick single-layer VN as well as the double-layer VN(30 nm)/Pd0.92Fe0.08(12 nm) and Pd0.96Fe0.04(20 nm)/VN(30 nm) structures have grown cube-on-cube epitaxially. Electric resistance measurements demonstrate a metallic-type temperature dependence for the VN film with a small residual resistivity of 9 μΩ·cm at 10 K, indicating high purity and structural quality of the film. The transition to the superconducting state was observed at 7.7 K for the VN film, at 7.2 K for the Pd0.96Fe0.04/VN structure and at 6.1 K for the VN/Pd0.92Fe0.08 structure with the critical temperature decreasing due to the proximity effect. Contrary to expectations, all transitions were very sharp with the width ranging from 25 mK for the VN film to 50 mK for the VN/Pd0.92Fe0.08 structure. We propose epitaxial single-crystalline thin films of VN and heteroepitaxial Pd1−xFex/VN and VN/Pd1−xFex (x ≤ 0.08) structures grown on MgO(001) as the materials of a choice for the improvement of superconducting magnetic random access memory characteristics.

Recovering metallic Pb directly from lead smelting dust by NaOH-carbon roasting process

Systematic chemical and mineralogical analyses were conducted for the dust generated in the Shuikoushan (SKS) lead smelting process, based on the results, an alternative strategy of direct metallic Pb recovery was proposed using NaOH–carbon roasting process. The reduction thermodynamics of PbSO4 was discussed, and the influencing parameters, including NaOH/dust mass ratio, carbon/dust mass ratio, roasting temperature and roasting time, were investigated systematically by experiments. The results indicated that increasing in the operation conditions was beneficial for the improved Pb recovery rate, and the reaction mechanism in this study was presumed as PbSO4→ C PbS→ NaOH Pb. The optimal conditions were determined as NaOH/dust mass ratio of 1.0, carbon/dust mass ratio of 0.2, roasting temperature of 650 °C and roasting time of 180 min. Under these conditions, 87.33% of Pb in the dust was directly recovered as metal pellets, gathering 96.48% of Bi, and 97.06% of As was converted into the alkali solution, while Zn and Cd were retained in the leaching residue. This process is clean and environmentally friendly for recovery of secondary resources bearing high content of PbSO4.

Improving steel melting intensity in the process of electrosmelting from waste and pellets (HBI)

The paper addresses the issue on improving the intensity of melting in the production of steels using hot briquetted iron (HBI) in the charge that mostly consists of metal waste. An analysis has been performed into the features of melting that uses charge of complex composition. To ensure the boiling of metal bath, it is recommended to introduce to the bath carbon-containing raw materials in the form of steel waste in the amount exceeding 80 %. It was established that applying HBI almost does not reduce the yield of usable metal due to a high content of metal waste that makes up the charge.At the same time, the paper analyses the role of silicon and manganese oxidation process in the refining of liquid steel at melting the alloy wastes used as charge materials in an electric arc furnace. The dependences of equilibrium concentrations of oxygen and silicon at different temperatures in the system Fe‒Si‒O have been given. In addition, the dependence diagram of manganese oxidation products in a liquid iron on the temperature and concentration of manganese in the alloy MnO‒FeO has been constructed. The equilibrium concentrations of oxygen and silicon with carbon deoxidizing capability have been defined, in the field of liquid silicates and in the field of solid SiO2.The high-quality silicon and manganese oxidation when smelting steel made from metal waste and hot briquetted iron (HBI) contributes to the fullest refining of liquid steel through the phases metal-slag or metal-gas.It has been shown that the content of silicon during electrical steel refining drops to traces. Thus, when using metal waste and pellets as charge in the steel-making process, a silicon oxidation reaction does not reach equilibrium. If a sour process is performed, then the oxidation of silicon reaches equilibrium and, under certain conditions for melting the charge under the influence of heat from an electric arc, there may occur a significant reduction of silicon that takes place at a higher temperature (a silicon-reducing process). The basic process of melting the charge from metal waste and hot briquetted iron in an electric arc furnace has been recommended. In this case, the reducing period of melting is aimed at metal deoxidation, sulphur removal, at bringing the chemical composition of steel to the preset composition, at controlling the process temperature. All these tasks are solved in parallel throughout the entire reduction period. The complete removal of oxidative slag was followed by adding to the furnace of slag-forming mixes together with deoxidizing agents, that is the new slag (carbide or white) was introduced.A rise in the furnace bath temperature decreases the equilibrium constant of manganese. Therefore, in the absence of ferromanganese additives in the bath in the process of melting refinement, the behavior of manganese in the bath can be an indicator for the metal temperature.

Comparing erosion and organ accumulation rates of lead and alternative lead-free ammunition fed to captive domestic ducks.

Lead poisoning of birds of prey from ingestion of ammunition lead has been well documented. Alternative, lead-free ammunition is widely available, but the toxicokinetics of other metals in birds are poorly understood. We tested the erosion of lead, copper, zinc, iron and brass by feeding domestic Pekin ducks (Anas platyrhynchos forma domestica) defined numbers of small metal pellets. The accumulation of these metals was analysed in the breast muscle, brain, pancreas, liver and kidney. Four weeks after application, the ducks were euthanized and necropsied, internal organs tested for metal accumulation and gizzard pellets collected and weighed to record loss by erosion. Degree of erosion was highest in zinc pellets (81% mass loss), followed by iron (46%) and lead (45%) and was only marginal in copper and brass. Only lead showed highly elevated levels of accumulation in organs compared to controls.

A gravitational approach to modeling the representative volume geometry of particle-reinforced metal matrix composites

Computational models of representative volumes of metal matrix composites are crucial for investigating material behavior on the microscale. Numerical simulations often employ finite element models of representative volumes. Such models are based on observations of material microstructural properties, for example, by means of electron microscopy. Constructing a geometrical model of a representative volume for further computations can be a tedious task. This paper presents a new approach to creating geometrical models of this kind. The approach is based on the simulation of rigid body motion in a gravitational field and allows one to automatically generate geometrical models of representative volumes. The approach capabilities are exemplified by two geometrical models of representative volume. One model describes a metal matrix composite with high volume fraction of prismatic reinforcement particles, produced by liquid metal infiltration. The other model describes a metal matrix composite with high volume fraction of metal pellets, produced by powder metallurgy.

Non-linear vibrations of nuclear fuel rods

Abstract Single zirconium alloy nuclear fuel rods with clamped-clamped boundary conditions and subjected to harmonic excitation at various force levels were experimentally studied. Different configurations were implemented, and the fuel rods were tested in air and submerged in quiescent water. Moreover, the effect of the contained fuel pellets was also reproduced by representative metallic pellets inside the rods. Non-linear stiffness and damping parameters were extracted from experimental vibration response curves by means of a specifically-developed identification tool. For the cases where the fuel pellets were removed or axially compressed, it was found that the axial-symmetry of the fuel rod resulted in a pronounced one-to-one internal resonance. The internal motion of the fuel pellets is a source of friction and impacts during vibrations, thus complicating further the linear and non-linear dynamic behavior of the system. A very significant increase of the viscous modal damping with the vibration amplitude was observed during geometrically non-linear vibrations, which is particularly relevant and in advantage of safety.

CuNi Alloy Electrodeposition for Microbumps Using Benzotriazole

A pressing issue in flip-chip and stacked integrated circuit (SIC) technology is the breakdown of microbumps over time. These microbumps are the physical and electrical connections between the chips. They consist out of Cu stages on both chips which are typically soldered together by Sn. Due to diffusion and electromigration, Cu and Sn form two intermetallic phases of which Cu3Sn induces microvoids at the Cu3Sn/Cu interface causing in turn breakdown of the microbump. Chemical modelling shows that a CuNi alloy, with an approximate 9:1 Cu:Ni ratio, together with Sn doesn’t form the Cu3Sn intermetallic compound thus tremendously improving the stability of the microbumps, and therefore the chip. By far the most feasible method to manufacture microbumps is galvanostatic electrochemical deposition. However, electrochemical CuNi co-deposition from a single deposition bath requires current densities higher than the limiting current density of copper causing rough, uncontrolled dendritical growth of Cu. Existing CuNi baths are citrate based but citrates can corrupt other features of the chip manufacturing process. In this work the possibility of smooth, solid solution electrodeposition of CuNi in a 9:1 ratio using benzotriazole (BTA) is investigated. Benzotriazole is a well-known corrosion inhibitor for copper. Here we show that BTA has a tremendous potential for suppressing Cu2+ reduction and limiting the uncontrolled mass-transfer limited Cu growth. First we demonstrate with a RDE voltammetric investigation, together with viscosimetry, the effects of the combination of an existing CuSO4 and a NiSO4 bath on Cu2+ reduction. Then, we introduce BTA and show the large difference between the working of BTA in the combined bath and in a CuSO4 only bath. Later, we improve the working of BTA by increasing the pH thus defining a parameter window for which we’re able to deposit CuNi with a maximum suppressing effect of BTA. CuNi deposits on metal pellets with a Cu substrate layer are investigated by SEM and EDX to evaluate the morphology and elemental composition of the deposit. We were able to demonstrate the change in CuNi morphology upon increasing the BTA concentration from 0 to 1000 ppm. No distinction could be made in Cu or Ni rich areas over different deposit areas indicating that we’re able to deposit CuNi as a solid solution. Figure 1

Large-Scale Consumption and Zero-Waste Recycling Method of Red Mud in Steel Making Process

To release the environmental pressure from the massive discharge of bauxite residue (red mud), a novel recycling method of red mud in steel making process was investigated through high-temperature experiments and thermodynamic analysis. The results showed that after the reduction roasting of the carbon-bearing red mud pellets at 1100–1200 °C for 12–20 min, the metallic pellets were obtained with the metallization ratio of ≥88%. Then, the separation of slag and iron achieved from the metallic pellets at 1550 °C, after composition adjustment targeting the primary crystal region of the 12CaO·7Al2O3 phase. After iron removal and composition adjustment, the smelting-separation slag had good smelting performance and desulfurization capability, which meets the demand of sulfurization flux in steel making process. The pig iron quality meets the requirements of the high-quality raw material for steel making. In virtue of the huge scale and output of steel industry, the large-scale consumption and zero-waste recycling method of red mud was proposed, which comprised of the carbon-bearing red mud pellets roasting in the rotary hearth furnace and smelting separation in the electric arc furnace after composition adjustment.

Shaking up gold and palladium

Sometimes, chemistry can be a real grind. But for Tomislav Friscic at McGill University, that’s the whole point. His team has developed a mechanochemical method that turns noble metals like gold and palladium into useful salts and complexes without needing solvents or harsh reagents (Angew. Chem. Int. Ed. 2018, DOI: 10.1002/anie.201712602). Noble metals are widely used in applications, including as catalysts and in electronics, but generating soluble noble metal compounds requires some aggressive conditions. A common way to make their chloride salts, for example, involves reacting the metals with aqua regia, a mixture of concentrated nitric and hydrochloric acids. Friscic’s team came up with a convenient and less hazardous alternative. The chemists mixed metal powder, pellets, or wire with potassium peroxymonosulfate, an oxidizing agent commonly known as Oxone, and simple halide salts such as potassium chloride or ammonium chloride. Then they put the mixture in a zirconia jar with a

Development status of microcell UO2 pellet for accident-tolerant fuel

Abstract A microcell UO2 pellet, as an accident-tolerant fuel pellet, is being developed to enhance the accident tolerance of nuclear fuels under accident conditions as well as the fuel performance under normal operation conditions. Improved capture-ability for highly radioactive and corrosive fission product (Cs and I) is the distinct feature of a ceramic microcell UO2 pellet, and the enhanced pellet thermal conductivity is that of a metallic microcell UO2 pellet. The fuel temperature can be effectively decreased by enhanced thermal conductivity. In this study, the material concepts of metallic and ceramic microcell UO2 pellets were designed, and the fabrication process of microcell UO2 pellets embodying the designed concept was developed. We successfully implemented the microcell UO2 pellets and produced microcell UO2 pellets. In addition, an assessment of the out-of-pile properties of a microcell UO2 pellet was performed, and the in-reactor performance and behavior of the developed microcell pellets were evaluated through a Halden irradiation test. According to the expectations, the excellent performance of the microcell UO2 pellets was confirmed by the online measurement data of the Halden irradiation test.

Application of two-component technological media for surface processing with a high degree of curvature

The final dimensional combined treatment with the application of an electric field by a tool in the form of unbound metal pellets of complex profile components used in aviation, rocket and space technology and in the oil and gas industry is considered. Such parts include impellers and the flowing component of the turbo-pump units, augers, impellers, where there are sections of variable curvature with limited access of the tool to the processing area. It is shown that the combination in a combined process of two-component technological media from current-carrying granules and an electrically conductive liquid medium supplied at high speed to the treatment zone allows to provide the required technological and operational processing parameters; the action of an electric field from a source with an increased voltage makes it possible to remotely perform a final dimensional processing of the pieces of metal parts with the creation of the required coldhardening against the impacts of solid granules; a combination of mechanical, chemical and magnetic impacts ensures obtaining a given profile accuracy, surface roughness. As a result, it is possible to increase the action and durability of important units of aerospace engineering and oil and gas equipment, and also to expand the area of technological use of the combined treatment method with unbound granules to component parts that are not accessible for processing by an integral tool. In the method under consideration, a universal granule tool is used which does not have a constant geometric shape and is capable of being delivered to the treatment zone through openings into parts whose dimensions are commensurable with the cross-section of the granules.

Patient with Hemiparkinsonism Secondary to a Gun Pellet in the Contralateral Substantia Nigra.

A 33 year-old male presented with right upper limb rest tremor that disappeared on action, posture associated with bradykinesia, and rigidity of right upper and lower limbs (Video S1). Patient also presented right-sided pyramidal weakness (grade 4), hyperreflexia, extensor plantar response, and hemihypesthesia. Skull X-ray and computed tomography (CT) of the brain showed several metal pellets producing multiple artifacts (Fig. 1A,B). Only one pellet settled in brain parenchyma (left midbrain), while other pellets settled in the skull bone (Fig. 1A). Transcranial sonography (TCS) was performed, confirming that the midbrain pellet was placed within the left substantia nigra (Fig. 1C). Levodopa challenge test was conducted, showing no improvement (pre- and post-l-dopa motor UPDRS were 21 and 20, respectively). A further chronic trial of l-dopa (for 3 months) also proved negative. Biperiden and propranolol were also tried with negative results. Figure 1Computed tomography (CT) of the brain and X-ray skull showed several pellets that produced multiple streak artifacts (Fig. 1A,B). Only one pellet rested in the brain parenchyma, the left (contralateral) midbrain as detected by CT (Fig. 1A), and transcranial sonography (Esaote MyLab Five, Providian, Italy) via temporal window (Fig. 1C). Abbreviations: SN, substantia nigra.Hemiparkinsonism has been previously reported secondary to midbrain lesions.1, 2 To the best of our knowledge, movement disorders (secondary to brain injuries) related to bullet fragments have been scantly reported. In one reported case, hemiparkinsonism and dystonia were the result of a bullet in midbrain,2 and in another, dystonia was caused by a bullet in internal capsule.3.

Image-guided percutaneous removal of ballistic foreign bodies secondary to air gun injuries.

Ballistic injuries with retained foreign bodies from air guns is a relatively common problem, particularly in children and adolescents. If not removed in a timely fashion, the foreign bodies can result in complications, including pain and infection. Diagnostic methods to identify the presence of the foreign body run the entire gamut of radiology, particularly radiography, ultrasound (US) and computed tomography (CT). Removal of the foreign bodies can be performed by primary care, emergency, surgical, and radiologic clinicians, with or without imaging guidance. To evaluate the modalities of radiologic detection and the experience of image-guided ballistic foreign body removal related to air gun injuries within the interventional radiology department of a large pediatric hospital. A database of more than 1,000 foreign bodies that were removed with imaging guidance by the interventional radiologists at our institution was searched for ballistic foreign bodies from air guns. The location, dimensions, diagnostic modality, duration, complications and imaging modality used for removal were recorded. In addition, the use of sedation and anesthesia required for the procedures was also recorded. Sixty-one patients with ballistic foreign bodies were identified. All foreign bodies were metallic BBs or pellets. The age of the patients ranged from 5 to 20 years. The initial diagnostic modality to detect the foreign bodies was primarily radiography. The primary modality to assist in removal was US, closely followed by fluoroscopy. For the procedure, 32.7% of the patients required some level of sedation. Only two patients had an active infection at the time of the removal. The foreign bodies were primarily in the soft tissues; however, successful removal was also performed from intraosseous, intraglandular and intratendinous locations. All cases resulted in successful removal without complications. Image-guided removal of ballistic foreign bodies secondary to air guns is a very effective procedure that can obviate the need for open surgical procedures in children.

Methods to ensure optimal off-bottom and drill bit distance under pellet impact drilling

The paper describes pellet impact drilling which could be used to increase the drilling speed and the rate of penetration when drilling hard rock for various purposes. Pellet impact drilling implies rock destruction by metal pellets with high kinetic energy in the immediate vicinity of the earth formation encountered. The pellets are circulated in the bottom hole by a high velocity fluid jet, which is the principle component of the ejector pellet impact drill bit. The paper presents the survey of methods ensuring an optimal off-bottom and a drill bit distance. The analysis of methods shows that the issue is topical and requires further research.

3 차원 프린팅 기술을 이용한 신개념 경수로 핵연료 기술 개발에 관한 연구

To enhance the safety of nuclear reactors after the Fukushima accident, researchers are developing various types of accident tolerant fuel (ATF) to increase the coping time and reduce the generation of hydrogen by oxidation. Coated cladding, an ATF concept, can be a promising technology in view of its commercialization. We applied 3D printing technology to the fabrication of coated cladding as well as of coated pellets. Direct metal tooling (DMT) in 3D printing technologies can create a coated layer on the tubular cladding surface, which maintains stability during corrosion, creep, and wear in the reactor. A 3D laser coating apparatus was built, and parameter studies were carried out. To coat pellets with erbium using this apparatus, we undertook preliminary experiments involving metal pellets. The adhesion test showed that the coated layer can be maintained at near fracture strength.

Modeling pellet impact drilling process

The paper describes pellet impact drilling which could be used to increase the drilling speed and the rate of penetration when drilling hard rocks. Pellet impact drilling implies rock destruction by metal pellets with high kinetic energy in the immediate vicinity of the earth formation encountered. The pellets are circulated in the bottom hole by a high velocity fluid jet, which is the principle component of the ejector pellet impact drill bit. The experiments conducted has allowed modeling the process of pellet impact drilling, which creates the scientific and methodological basis for engineering design of drilling operations under different geo-technical conditions.

Reduction of Carbon-bearing Pellets of Oolitic Hematite in a Shaft Furnace

AbstractWhen carbon-bearing pellets of oolitic hematite are treated in a shaft furnace, some problems are typically encountered: the metallization ratio of the metal pellets is low; the carbon-bearing pellets bond with each other at high temperatures; and the separation of phosphorus from iron is difficult. To solve these problems, experiments were conducted on oolitic hematite reduction in a resistance furnace and semi-industrial test shaft furnace. The results showed that the metallization rate reached 90% or greater under the conditions of a reduction temperature of 1150 °C, an atmosphere of simulated flue gas, and a reduction time between 1. 5 and 2. 0 h. The problem of high-temperature bonding among pellets can be solved by increasing the strength of the pellets, coating their surface with a surface transfer agent and maintaining an even temperature inside the shaft furnace. The basicity of the ore blend exerted no obvious effect on the magnetic concentrate and phosphorus content. The phosphorus content in the magnetic concentrate can be further reduced by improving the grinding capacity of the ball mills used in the experiments. On the basis of the experimental results related to oolitic hematite reduction with carbon-bearing pellets in a shaft furnace, the experimental requirements were satisfied with an average 88. 27% total Fe content and 0. 581% P content in the pellets.

Homicide by Three Different Firearms or Single Improvised Weapon: The Forensic Pathologist's Dilemma

The recovery of different constituents of ammunitions in a dead body is of vital importance for investigation of firearm fatalities. The projectile that enters the body depends on the type of firearm used. The wound of entry and the wound of exit and the track are useful guides for reconstructing the incident of firearm injury. Most often, at autopsy, these projectiles are recovered from the body and preserved as materials of evidential values. This is further complicated when changes due to decomposition obscure and modify the appearances of the wounds of the entry and exists. In our country, especially with advent of readily available improvised firearms, the classical assembly of arms and weapons are not found. Handmade or improvised firearms produce injuries that are often unique and special. Here, we report a rare case of finding one revolver bullet, one country-made rifled bullet, and one shotgun felt wad along with multiple metallic pellets, all in a single decomposed body.

Crystallization and precipitation of phosphate from swine wastewater by magnesium metal corrosion.

This paper presents a unique approach for magnesium dosage in struvite precipitation by Mg metal corrosion. The experimental results showed that using an air bubbling column filled with Mg metal and graphite pellets for the magnesium dosage was the optimal operation mode, which could significantly accelerate the corrosion of the Mg metal pellets due to the presence of graphite granules. The reaction mechanism experiments revealed that the solution pH could be used as the indicator for struvite crystallization by the process. Increases in the Mg metal dosage, mass ratio of graphite and magnesium metal (G:M) and airflow rate could rapidly increase the solution pH. When all three conditions were at 10 g L–1, 1:1 and 1 L min–1, respectively, the phosphate recovery efficiency reached 97.5%. To achieve a high level of automation for the phosphate recovery process, a continuous-flow reactor immersed with the graphite-magnesium air bubbling column was designed to harvest the phosphate from actual swine wastewater. Under conditions of intermittently supplementing small amounts of Mg metal pellets, approximately 95% of the phosphate could be stably recovered as struvite of 95.8% (±0.5) purity. An economic analysis indicated that the process proposed was technically simple and economically feasible.