Mixture Of Silicon Research Articles

Enhancing the combustion of silicon nanoparticles via plasma-assisted fluorocarbon surface modification

Nanostructured silicon has great potential as an energetic material due to its high energy density, close to that of aluminum; however, its combustion kinetics are strongly affected by the presence of a native oxide layer. As the particle size is reduced, the material behavior is dominated by surface effects, highlighting the need for new approaches to fabricate silicon nanoparticles and precisely control their surface chemistry. Here, we describe the use of low-temperature plasma to nucleate and grow < 10 nm silicon particles. The resulting aerosol is passed through a second plasma reactor, to which a fluorocarbon monomer is supplied. The second plasma initiates the growth of a polymeric shell onto the silicon particles, resulting in a highly conformal coating. Chemical analysis confirms that the polymer shell is compositionally similar to polyvinylidene fluoride (PVDF). We find that the fluorocarbon shell acts as an artificial passivation layer that significantly delays the onset of oxidation in air. In addition, the direct contact between the fluorocarbon shell and silicon core lowers the ignition temperature compared to the physical mixtures of silicon nanoparticles and PVDF. It leads to a higher pressurization rate and a lower combustion time when tested in a combustion cell. This is consistent with the combustion process being initiated by the exothermic interfacial reactions between the silicon core and the fluorocarbon shell. Mass spectroscopy confirms this hypothesis because silicon fluoride is produced only for the core–shell structure, and not for a physical mixture of silicon and PVDF. This study provides an example of a new processing technique capable of controlling the interfacial chemistry of small nanoparticles with beneficial effects on their combustion.

Comprehensive clinical implementation, workflow, and FMEA of bespoke silicone bolus cast from 3D printed molds using open-source resources.

Bolus materials have been used for decades in radiotherapy. Most frequently, these materials are utilized to bring dose closer to the skin surface to cover superficial targets optimally. While cavity filling, such as nasal cavities, is desirable, traditional commercial bolus is lacking, requiring other solutions. Recently, investigators have worked on utilizing 3D printing technology, including commercially available solutions, which can overcome some challenges with traditional bolus. To utilize failure modes and effects analysis (FMEA) to successfully implement a comprehensive 3D printed bolus solution to replace commercial bolus in our clinic using a series of open-source (or free) software products. 3D printed molds for bespoke bolus were created by exporting the DICOM structures of the bolus designed in the treatment planning system and manipulated to create a multipart mold for 3D printing. A silicone (Ecoflex 00-30) mixture is poured into the mold and cured to form the bolus. Molds for sheet bolus of five thicknesses were also created. A comprehensive FMEA was performed to guide workflow adjustments and QA steps. The process map identified 39 and 30 distinct steps for the bespoke and flat sheet bolus workflows, respectively. The corresponding FMEA highlighted 119 and 86 failure modes, with 69 shared between the processes. Misunderstanding of plan intent was a potential cause for most of the highest-scoring failure modes, indicating that physics and dosimetry involvement early in the process is paramount. FMEA informed the design and implementation of QA steps to guarantee a safe and high-quality comprehensive implementation of silicone bolus from 3D printed molds. This approach allows for greater adaptability not afforded by traditional bolus, as well as potential dissemination to other clinics due to the open-source nature of the workflow.

Perceptibility and acceptability thresholds for color differences of light and dark maxillofacial skin replications

The aim of this study was to assess the perceptibility and acceptability thresholds of maxillofacial silicones for light and dark skin colors and to evaluate the effect of gender and professional experience on these thresholds. Two different sets of specimens (as light and dark) each, consisting of 14 (25 × 25 × 6-mm3) silicone skin replications, were produced. Four specimens of each set were produced from the same silicon mixture of the relevant set and polymerized simultaneously to provide standardized fabrication conditions. These 4 light/dark specimens were assigned as “baseline color specimens (BCs)” in each set, while the other 10 specimens were produced with a color difference level that increased gradually from BC. These stepped levels were obtained by controlled increasing of the pigment concentration in the relevant baseline silicon mixture. Color difference levels of specimens were calculated by using the CIELAB and CIEDE2000 formulas. Observers comprised of 3 different professional experiences as first-year dental students, interns, and dentists (n = 30/group, gender-balanced) were included. Combinations consisting of 5 specimens with 4 BCs and 1 different color were shown to the observers to assess whether the color difference was perceptible or acceptable. Perceptibility and acceptability percentages were regressed with color difference levels to estimate the best fit curve and confidence intervals were calculated (α = 0.05). The highest estimation of the coefficient of determination (R2) was found in the cubic curve for all parameters. A significant difference was found between the light and dark colors. The perceptibility thresholds (ΔE*ab/ΔE00) were 0.8/0.59 and 2.63/1.75 for light and dark colors, respectively. The acceptability thresholds (ΔE*ab/ΔE00) were 3.35/2.25, 10.07/7.04 for light and dark colors, respectively. No significant differences were found between gender and among experience groups concerning visual thresholds. Regardless of gender and experience, observers could perceive color differences more easily in light skin colors.

Oil resistivity of fluorine-free foams stabilized by silica nanoparticles and mixture of silicone and hydrocarbon surfactants

Oil resistivity of fluorine-free foams stabilized by silica nanoparticles and mixture of silicone and hydrocarbon surfactants

Continuously stirred tank reactor for oil-suspended thermochemical energy storage systems for CuSO4·5H2O

Thermochemical energy storage can be used for heating applications, thereby helping to cut down on greenhouse gases from burning non-renewable fuels by offering a solution for seasonal heat storage. In the scope of the EU project RESTORE, a thermochemical energy storage is used to store low temperature waste heat and use it for district heating. This study presents the thermochemical energy storage as a new continuously stirred tank three-phase suspension reactor for storing heat from renewable sources or waste heat with almost no losses, in reaction. Therefore, the reactor was built of glass, where process parameters, such as the mean residence time, have been varied to obtain optimized results for thermochemical energy storage operating at the fixed temperature of 125 °C chosen due to project restrictions. The heat is used to dehydrate CuSO4·5H2O in the charging step and recovered by rehydrating CuSO4·3H2O or CuSO4·H2O, respectively, while generating heat in the discharging step. Using a mixture of silicone and mineral oil to prevent foaming, conversion rates of over 94 % to CuSO4·H2O were reached in the charging step with the continuously stirred tank reactor, with 1 kW thermal power, 150 mm diameter and 900 mm height in continuous operation. In discharging operation, 100 % conversion from CuSO4·H2O to CuSO4·5H2O was measured. This paper lays the groundwork for a new technology for thermochemical heat storage in low temperature application.

Creation and Validation of a Novel 3-Dimensional Pediatric Hip Ultrasound Model.

The aim of this study was to create and validate a 3-dimensional (3D) ultrasound model with normal and abnormal pediatric hip joint anatomy that is comparable to a pediatric hip joint in appearance and anatomy and replicates sonographic characteristics of a pediatric hip joint. A 3D rendering of the bone and soft tissue was created from a computed tomography pelvic scan of a pediatric patient. This rendering was modified to include a unilateral joint effusion. The bone was 3D printed with a photopolymer plastic, whereas the soft tissue was cast with a silicone mixture in a 3D-printed mold. The effusion was simulated by injecting saline into the soft tissue cavity surrounding the bone. The ultrasound model was validated by pediatric point-of-care ultrasonographers at an international pediatric ultrasound conference. A pediatric hip ultrasound model was developed that simulates both normal and abnormal pediatric hip joint anatomy, each with an appropriately sized, measurable joint effusion. Validation by pediatric point-of-care ultrasonographers showed that the key aspects of a normal pediatric hip joint (femoral physis, sloped femoral neck, and adequate soft tissue) with an identifiable and measurable effusion were included in the ultrasound model. In this study, we successfully created a cost-effective, reusable, and reproducible 3D pediatric hip ultrasound model. The majority of pediatric point-of-care ultrasonographers who evaluated the model agreed that this model is comparable to a pediatric patient for the purpose of teaching ultrasound skills and joint space measurement.

Experimental Study on Foam Properties of Mixtures of Organic Silicon and Hydrocarbon Surfactants Regulated by Nano-SiO2 Particles

Experimental Study on Foam Properties of Mixtures of Organic Silicon and Hydrocarbon Surfactants Regulated by Nano-SiO2 Particles

Mechanical effects of nanomaterials on the residual shear strength of dry sandy mixtures: Implication for the high mobility of rock avalanches

Nanoparticles found in rock avalanches and natural faults were inferred to be the reason for the ultra-low shear resistance of the materials along the shear surface. Nevertheless, this inference has not been physically verified yet. To investigate the role of nanoparticles in the shear behavior of granular materials, we conducted a series of ring shear tests on silicon dioxide nanoparticles (SN), silica sand (S8), and mixtures of the S8 with different contents of SN, under varying normal stresses (σ) and shear velocities (V). Our results showed that the shear strength (μ) of SN is high when σ is small (≤ 215 kPa at our test range), even though the maximum shear velocity is about 210 cm/s, but shows a great decrease under higher σ (≥ 619 kPa). The shear strength of mixtures varied with SN content. For S8 (M0) and the mixture of 10% SN (M10), when sheared under small σ, μ first decreased slightly with increasing V when V is smaller than 1 cm/s, after that it increased slightly with further increase of V. Nevertheless, this kind of shear-rate dependent behavior was not observed in the tests under higher σ. When the content of SN in the mixture was <20%, μ increased with the increase of SN content. However, with further increase of SN content, μ decreased. Under high normal stress conditions, distinctive powder rolls were observed on the shear surface formed on the tests. When the mixtures with lower SN content (≤50%), the powder rolls were not observed. We inferred that powder rolls can be produced under high SN content and high normal stress conditions, and this structure altered the particle movement mode from sliding friction to rolling resistance, resulting in a significant decrease in the shear strength. These findings provide valuable insights into the shear behavior of granular materials with nanoparticles and then provide evidence for a better understanding of the high mobility of rock avalanches.

Effect of cyclic mechanical treatment on the final properties of Nb + 2Si powder mixtures prepared for SHS

The mechanical pretreatment of a powder mixture of niobium and silicon was studied experimentally and theoretically using the new macrokinetic theory of mechanochemical synthesis. The method of organizing the operation mode of the ball mill affects the degree of grinding and activation of the powder composition, as well as the rate of formation of intermediate phases. The effect of cycling on the temperature inside the mill drum, particle size of the powder mixture, formation of mechanically synthesized niobium silicides, and structure of the initial components has been studied. Varying the cycling can lead to safe and emergency operation of the mill. The final mixtures' characteristics may vary significantly depending on the number of cycles of discontinuous mechanical treatment, even if the total operating time of the ball mill remains the same. The safe conditions for cyclic operation of the mill were determined. The effects of different mechanical treatment modes on the grinding, activation, and phase formation of a powder mixture were investigated. Various parameters were analyzed, including thermophysical, physico-chemical, and kinetic characteristics of the cyclic operation of the AGO-3 ball mill, the kinetics of grinding and activation of Nb and Si particles, and the rate of mechanochemical reaction in the mechanically activated mixture of Nb + 2Si.

Development of a Low-cost Epimysial Electromyography Electrode: A Simplified Workflow for Fabrication and Testing.

Electromyography (EMG) is a valuable diagnostic tool for detecting neuromuscular abnormalities. Implantable epimysial electrodes are commonly used to measure EMG signals in preclinical models. Although classical resources exist describing the principles of epimysial electrode fabrication, there is a sparsity of illustrative information translating electrode theory to practice. To remedy this, we provide an updated, easy-to-follow guide on fabricating and testing a low-cost epimysial electrode. Electrodes were made by folding and inserting two platinum-iridium foils into a precut silicone base to form the contact surfaces. Next, coated stainless steel wires were welded to each contact surface to form the electrode leads. Lastly, a silicone mixture was used to seal the electrode. Ex vivo testing was conducted to compare our custom-fabricated electrode to an industry standard electrode in a saline bath, where high levels of signal agreement (sine [intraclass correlation - ICC= 0.993], square [ICC = 0.995], triangle [ICC = 0.958]), and temporal-synchrony (sine [r = 0.987], square [r = 0.990], triangle [r= 0.931]) were found across all waveforms. Low levels of electrode impedance were also quantified via electrochemical impedance spectroscopy. An in vivo performance assessment was also conducted where the vastus lateralis muscle of a rat was surgically instrumented with the custom-fabricated electrode and signaling was acquired during uphill and downhill walking. As expected, peak EMG activity was significantly lower during downhill walking (0.008 ± 0.005 mV) than uphill (0.031 ± 0.180 mV, p = 0.005), supporting the validity of the device. The reliability and biocompatibility of the device were also supported by consistent signaling during level walking at 14 days and 56 days post implantation (0.01 ± 0.007 mV, 0.012 ± 0.007 mV respectively; p > 0.05) and the absence of histological inflammation. Collectively, we provide an updated workflow for the fabrication and testing of low-cost epimysial electrodes.

Nuclear power plant pipeline detection robot based on a new radiation-proof material

Soft robots are gradually gaining recognition in recent years for their ability to work in extreme environments. However, radiation shielding is a major issue when designing soft robots for use in nuclear environments. In this paper we present an effective soft robot design and develop new radiation shielding materials that enable the robot to perform a variety of tasks in the complex pipelines of a nuclear power plant while being sufficiently radiation shielded. To achieve this, we used a mixture of silicone and lead powder with excellent radiation shielding capabilities and designed and built a soft robot prototype consisting of multiple pneumatic actuators and a resin frame. It is capable of moving through complex pipelines and performing inspection tasks, while also providing radiation shielding for the internal components of the robot. Finite element simulations and prototype experiments were then carried out to evaluate the robot's performance in various scenarios. Simulation results show that the soft robot is able to perform inspection of nuclear power plant pipelines efficiently and effectively. Furthermore, the radiation shielding provided by the radiation-proof material is effective in protecting the internal components of the robot from radiation exposure. In conclusion, we have successfully developed a soft robot prototype that is capable of performing pipeline inspections in extreme environments such as nuclear power plants, while providing adequate radiation shielding. The proposed approach can be extended to other soft robotics applications in the nuclear environment and has the potential to improve the safety and efficiency of nuclear power plant operations.

Mechanical testing and comparison of porcine tissue, silicones and 3D-printed materials for cardiovascular phantoms.

Background: Cardiovascular phantoms for patient education, pre-operative planning, surgical training, haemodynamic simulation, and device testing may help improve patient care. However, currently used materials may have different mechanical properties compared to biological tissue. Methods/Aim: The aim of this study was to investigate the mechanical properties of 3D-printing and silicone materials in comparison to biological cardiovascular tissues. Uniaxial cyclic tension testing was performed using dumbbell samples from porcine tissue (aorta, pulmonary artery, right and left ventricle). Flexible testing materials included 15 silicone (mixtures) and three 3D-printing materials. The modulus of elasticity was calculated for different deformation ranges. Results: The modulus of elasticity (0%-60%) for the aorta ranged from 0.16 to 0.18N/mm2, for the pulmonary artery from 0.07 to 0.09N/mm2, and for the right ventricle as well as the left ventricle short-axis from 0.1 to 0.16N/mm2. For silicones the range of modulus of elasticity was 0.02-1.16N/mm2, and for the 3D-printed materials from 0.85 to 1.02N/mm2. The stress-strain curves of all tissues showed a non-linear behaviour in the cyclic tensile testing, with a distinct toe region, followed by exponential strain hardening behaviour towards the peak elongation. The vessel samples showed a more linear behaviour comparted to myocardial samples. The silicones and 3D printing materials exhibited near-linearity at higher strain ranges, with a decrease in stiffness following the initial deformation. All samples showed a deviation between the loading and unloading curves (hysteresis), and a reduction in peak force over the first few cycles (adaptation effect) at constant deformation. Conclusion: The modulus of elasticity of silicone mixtures is more in agreement to porcine cardiovascular tissues than 3D-printed materials. All synthetic materials showed an almost linear behaviour in the mechanical testing compared to the non-linear behaviour of the biological tissues, probably due to fibre recruitment mechanism in the latter.

Analogue modelling of the Ainsa oblique zone in the Southern Central Pyrenees, Spain

The Pyrenees are a collisional orogen striking WNW-ESE. However, in the Ainsa oblique zone in the south-central part of the Pyrenees, faults and folds rotate to ∼N–S over a westward thinning evaporitic layer. The influence of lateral change in basal friction due to declining evaporitic layer thickness in a fold-and-thrust belt is studied by analogue modelling simulating the Ainsa oblique zone. In the experiments the transition zone is simulated by a viscous silicone mixture sheet that laterally changes in thickness adjacent to frictional-plastic quartz-sand. The models confirm that a transition between weak and strong basal friction causes oblique structures to develop. Weak detachment zones are prone to fault propagation whereas strong detachment zones are prone to imbrication. At the transition zone those structural styles are combined, resulting in a complex domain. The differences in deformation style cause dextral shear and clockwise rotation in the transition zone and larger horizontal deformation propagation in the weak basal friction zone. Structures produced in the analogue models are compared to structures in the Ainsa oblique zone and found to be representative. Therefore, this study shows that transition between weak and strong detachment layers can explain the regional structural deformation style in the Ainsa oblique zone.

Graphene-based anode materials in Li-Ion batteries

Doubtlessly, one of the most used electric power storage technologies at the moment is the lithium-ion battery (LIB). Meanwhile, in order to meet increasing needs for the present LIB performance, the improvement on the anode materials of LIB is one of the major study approaches. Among a wide range of options like silicon, metal oxides, and other compounds and mixtures, this review will mainly focus on the graphene-related LIB anode materials. By discussing the preparation processes and the electrochemical performance of various types of graphene-based and graphene-coated materials that are used for the anode of LIBs, the improvements of the addition of graphene in other materials have been reviewed, and the patterns of that have been analysed. This review helps summarize the current typical research results of the electrochemical properties of LIB anode materials based on graphene and gives suggestions about the future research focus on this specific category of materials by referring to the comparison of the data reviewed.

Insights into the chemical characteristics of atmospheric aerosols from urban-industrial and rural sites in south-east of Poland during winter

This study focusses on a short-term characterisation of atmospheric aerosols from three locations in south- east of Poland with different land use characteristics, population density and sources of pollution (Katowice: urban-industrial; Strzyżowice near Lublin: rural; Kielce: urban). Twenty-four hour PM2.5 and PM10 samples were collected on the quartz filter and their chemical compositions were monitored and measured using OCEC thermo-optical analysis and scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS). The highest concentrations of PM2.5 and PM10 were measured at the urban-industrial area in Katowice (29.6 µg ∙ m−3 and 31.0 µg ∙ m−3, respectively), whereas the highest organic carbon (OC) and elemental carbon (EC) levels were observed at the Kielce urban site (23.3 ± 4.2 µg and 3.6 ± 0.3 µg, respectively). The lowest values were obtained at the rural site for PM2.5 (10.4 ± 2.7 µg ∙ m−3) and PM10 (11.8 ± 2.7 µg ∙ m−3) and for OC (17.8 ± 1.6 µg) and EC (1.0 ± 0.1 µg). SEM-EDS analysis of samples from Kielce allows identification of internal chemical mixtures of carbon, silicon, calcium, chlorine, sodium and aluminium.

Experimental study on the flexural, hardness, and tensile properties of pineapple and jute fiber-reinforced composite with SiC nanoparticles

This scientific investigation delves into the effects of minuscule particles created from a mixture of silicon and carbon, known as SiC nanoparticles, on the flexural, hardness, and tensile properties of composites made from fibers obtained from pineapple and jute. The researchers used a manual layering technique to make these composites, by blending varying amounts of fibers and SiC nanoparticles. Then proceeded to subject the composites to a series of tests to determine their resistance to bending, strength, and ability to bear tensile forces before breaking. The findings of the research reveal that the inclusion of SiC nanoparticles in the composites made from pineapple and jute fibers led to a significant improvement in their mechanical properties such as strength, stiffness, and toughness. The composites made using a greater proportion of fibers and nanoparticles exhibited the most substantial strength and stiffness. The addition of SiC nanoparticles also contributed to an increase in the composites' hardness, with the jute fiber composite displaying more improvement than the pineapple fiber composite. In terms of tensile strength and toughness, the composites with higher weight fractions of fibers and SiC nanoparticles displayed superior performance, with the jute fiber composite outperforming the pineapple fiber composite. These results suggest that utilizing SiC nanoparticles in composites made from natural fibers like pineapple and jute holds promise for producing premium quality materials that could serve multiple industries. Nevertheless, further studies are essential to refine the fabrication process and evaluate the long-term durability and performance of these composites. Overall, this research demonstrates the potential of using natural fiber-reinforced composites with nanoparticles to create sustainable, high-performance materials.

Fluctuation cepstral scanning transmission electron microscopy of mixed-phase amorphous materials

Four-dimensional scanning transmission electron microscopy (4D-STEM) is a versatile analytical tool for characterizing materials structural properties. However, extending such analysis to disordered materials is challenging, especially in technologically important samples with mixed ordered and disordered phases. Here, we present a new 4D-STEM method, called fluctuation cepstral STEM (FC-STEM), based on the fluctuation analysis of cepstral transform of diffraction patterns. The peaks in the associated transformation relate to inter-atomic distances in a thin sample. By varying the real-space range over which fluctuations are calculated, distinct ordered and disordered phases can be mapped in a diffractive image reconstruction. We demonstrate the principles of FC-STEM by characterizing a silicon anode, harvested from a cycled lithium-ion battery. A mixture of amorphous and nanocrystalline silicon, graphitic carbon, and electrolyte by-products is identified and mapped. Comparisons with conventional electron imaging and energy-dispersive X-ray spectroscopy show that FC-STEM is highly effective for the structure determination of mixed-phase amorphous materials.

Modifying nano-silicon with nano-antimony through molten salt electrolysis for superior lithium storage materials

The application of silicon to lithium-ion batteries (LIBs) remains a challenge due to the severe volume expansion effect of silicon. In this work, a nano Si-Sb bimetal is obtained by the molten salt electrolysis of mixture of silicon and antimony sulfide (Sb2S3). The uniform hybrid of antimony nanoparticles not only prevents the agglomeration of silicon but also selectively decomposes the electrolyte additives and alleviates the rupture of SEI effectively, which can mitigate the volume expansion of silicon. When used as a negative electrode for LIBs, the Si-Sb bimetallic electrode delivers a reversible capacity of 1524 mAh/g after 100 cycles at a current density of 1 A/g. Even at 3 A/g, the reversible capacity is as high as 1062 mAh/g after 200 cycles. This work offers a new way for the fabrication of Si-based alloy anodes through using molten salt electrolysis.

Effect of hydrophilic silica nanoparticles on foam properties of mixtures of silicone and hydrocarbon surfactants

Foams stabilized by nanoparticles (NPs) and surfactants have great application prospects in the development of fluorine-free firefighting foams. In the present study, hydrophilic SiO2 NPs, a nonionic silicone surfactant (CoatOsil-77), and a zwitterionic hydrocarbon surfactant (BS-12) were used to prepare mixed dispersions to investigate effect of NPs on properties of fluorine-free foams. The interactions between NPs and surfactants, foaming ability, and foam stability of the mixed dispersions were investigated. Results indicate that the surface activity, conductivity, and foaming ability of the mixed dispersions decreased with increasing NP concentration. The addition of NPs has a remarkable impact on foam stability of the mixed dispersions. The presence of NPs at a NP concentration above 2% leads to enhancement of foam stability by delaying foam drainage and coarsening. This study provides theoretical guidance for the application of NPs in fluorine-free foams.

Foam stabilized by the mixture of silicone and hydrocarbon surfactants in the presence of nanoparticles with different specific surface area

Foam stabilized by the mixture of silicone and hydrocarbon surfactants in the presence of nanoparticles with different specific surface area