Fluorocarbon Research Articles

Gold nanoparticle-coating reduces the acoustic pressure threshold for nanodroplet vaporization

Nanodroplets with a low-boiling-point perfluorocarbon (PFC) may vaporize spontaneously at physiological temperatures. Using a high-boiling-point PFC, e.g., perfluorohexane (PFH), can enable ultrasound-triggered vaporization for applications in imaging and drug delivery. However, PFH requires relatively high ultrasound (US) pressures for vaporization compared to low-boiling-point PFCs, making its use challenging. We investigated the feasibility of reducing the vaporization threshold by gold-coating lipid-encapsulated PFH nanodroplets (Au-PFH-NDs). We synthesized Au-PFH-NDs with 200 nm mean particle size and 5.12 × 10−4 pg mass of gold-coating per nanodroplet. B-mode images of the emulsion perfused in a flow phantom were used to determine the pressure threshold for ND vaporization upon exposure to 2 MHz focused US (f-number of 1.27, 0.5% duty cycle). The pressure threshold for Au-PFH-NDs (3.97 ± 0.63 MPa) was significantly lower (p < 0.05) than that of NDs without gold-coating (7.07 ± 0.02 MPa), indicating that gold-coating reduced the vaporization pressure threshold. In addition, the pressure threshold of the Au-PFH-NDs was not significantly different (p > 0.05) from that of perfluoropentane (PFP) NDs (4.16 ± 0.01 MPa). These results suggest that the Au-PFH-NDs can be vaporized at similar pressures as PFP NDs, but are more stable at physiological temperatures. These findings are the first step towards employing gold-coated PFC nanodroplets with a lower vaporization pressure threshold for multimodal imaging and drug delivery.

Droplets for acoustic vaporization: Formulations, properties and applications

The Acoustic Droplet Vaporization (ADV) (1), a phase-change of the droplets core from liquid to vapor phase upon ultrasound irradiation, burst renewed interest in droplet emulsions, a traditional topic of colloidal science, opening up innovative applications in biomedicine. Droplets undergoing ADV share similar liquid cores, typically perfluorocarbons (PFCs), however, the nature of the shells can be polymeric (2) or lipidic (3, 4). Such difference imparts to phase-change droplets diverse acoustic and mechanical behaviors (5). In this contribution we present some results concerning a general strategy for the formulation of polymer or lipid shelled submicron droplets. Other key points for the use of ADV-responsive in biomedical applications will be addressed. Recently we have extended the concepts of ADV to radiation responsive droplets for dosimetry in cancer treatment with hadronic radiation. Results on this activity will be also reported (6).

Seawater contamination by coring and pore water sampling of marine sediments

Coring of sediments with minimal physical disturbance, and sampling of pore water with minimal contamination from seawater, are critical in marine geochemistry and microbiology. Yet, sediment coring generally causes smearing of sediment down along the inside of the core liner and leaves seawater and fluid mud trapped around the core. This seawater is a source of diffusive or advective exchange of solutes with the core, which affects the chemistry of retrieved pore water. The exchange depends on the time elapsed between coring and the end of pore water extraction. The degree of seawater contamination is difficult to determine and has generally been neglected in the geochemical literature. Yet, it is possible to quantify seawater contamination due to the high millimolar concentration of sulfate in seawater and low micromolar concentration in the subsurface methanic zone, where sulfate is largely depleted. Analysis of 540 sediment cores from a global database showed that sulfate concentration data beneath the sulfate-methane transition were often truncated and stated as “0” or “0,0” mM, thereby preventing an evaluation of seawater contamination. Among the 181 sediment cores for which the mM sulfate concentrations were reported with two or three decimal places, concentrations measured in methanic sediments were up to an order of magnitude higher than the estimated in situ concentrations in gravity cores and two orders of magnitude higher in cores recovered by scientific ocean drilling. A comparison between pore water extraction by Rhizon suction samplers and by high-pressure squeezers in cores from Baltic Sea Expedition 347 of the IODP (International Ocean Discovery Program) showed no systematic difference in the degree of contamination. A comparison with a perfluorocarbon (PFC) tracer injected by IODP coring into the drilling fluid showed a seawater contamination similar to that based on sulfate in the methanic zone. In IODP cores, where the true in situ sulfate concentration is generally unknown, we calculated the theoretical sulfate concentration that corresponded to equilibrium between SO42−, Ba2+ and barite (BaSO4) to show that the equilibrium sulfate concentrations in the methanic zone are much lower than the sulfate concentrations measured in pore water samples, again indicating seawater contamination. We used a time-resolved diffusion model to calculate how contaminating seawater ions penetrate from the external liner fluid into sediment cores before pore water is extracted. We conclude that nearly all published pore water samples retrieved from subsurface sediments are contaminated by seawater to some degree. We also conclude that sensitive sulfate analyses in methanic sediments constitute a unique opportunity to quantify this contamination and thereby provide a better possibility to control it.

Exploring the Responses of Teak and Eucalyptus to Elevated Carbon Dioxide in a Changing Atmosphere

Global warming plays a major role in climate change that is mainly caused by the increase of atmospheric carbon dioxide (CO2) and other greenhouse gases (GHGs) such as Methane (CH4), Nitrous oxide(N2O) and Chloro Fluoro Carbons (CFC) level in the last two decades. These greenhouse gases partially absorb long wave radiation remitted by the earth’s warm surface and re-emit the same resulting in warming up in the atmosphere. Climate change can be identified by changes in mean and variability of its properties. Climate changes are operated by the increase of (Green House gases) of them Carbon dioxide (CO2) is one of the most important greenhouse gases because of which influence the growth and morphology of industrially important tree species in tropics. Teak and Eucalyptus are the economically important tree species grown throughout the world in current study found that morphological, physiological and biochemical changes under elevated CO2 conditions. Forests, comprising diverse ecosystems and housing a plethora of plant species, play a critical role in mitigating climate change by acting as carbon sinks. Among the key contributors to this dynamic, Teak and Eucalyptus, as prominent tropical tree species, have been identified for their potential to sequester carbon dioxide (CO2) and influence ecosystem dynamics. Understanding how these trees respond to elevated CO2 levels is imperative for predicting the resilience and adaptability of forest ecosystems in the face of ongoing climate change. As we navigate a changing climate, unraveling the intricacies of how these vital tree species interact with elevated CO2 provides crucial insights for informed forest management and conservation practices.

Superfluorinated, Highly Water-Soluble Polyphosphazenes as Potential 19F Magnetic Resonance Imaging (MRI) Contrast Agents.

"Hot spot" 19F magnetic resonance imaging (MRI) has garnered significant attention recently for its ability to image various disease markers quantitatively. Unlike conventional gadolinium-based MRI contrast agents, which rely on proton signal modulation, 19F-MRI's direct detection has a unique advantage in vivo, as the human body exhibits a negligible background 19F-signal. However, existing perfluorocarbon (PFC) or PFC-based contrast materials suffer from several limitations, including low longitudinal relaxation rates and relatively low imaging efficiency. Hence, we designed a macromolecular contrast agent featuring a high number of magnetically equivalent 19F-nuclei in a single macromolecule, adequate fluorine nucleus mobility, and excellent water solubility. This design utilizes superfluorinated polyphosphazene (PPz) polymers as the 19F-source; these are modified with sodium mercaptoethanesulfonate (MESNa) to achieve water solubility exceeding 360 mg/mL, which is a similar solubility to that of sodium chloride. We observed substantial signal enhancement in MRI with these novel macromolecular carriers compared to non-enhanced surroundings and aqueous trifluoroacetic acid (TFA) used as a positive control. In conclusion, these novel water-soluble macromolecular carriers represent a promising platform for future MRI contrast agents.

Abstract TP303: Perfluorocarbon Oxygent Limits Functional Impairment and Brain Damage Following Subarachnoid Hemorrhage

Introduction: Subarachnoid hemorrhage (SAH) is the deadliest form of hemorrhagic stroke. Post-SAH vasospasm induces brain tissue hypoxia-ischemia resulting in brain injury and functional impairments. However, translational studies focused on post-SAH brain tissue oxygenation for functional improvements remain limited. We propose the use of Oxygent, a perfluorocarbon (PFC) based lipid emulsion oxygen carrier, as a promising therapy to improve post-SAH functional outcomes. Here we propose the use of Oxygent, a perfluorocarbon (PFC), as effective therapeutics. Oxygent-PFC comes as a lipid emulsion of micro-particles with great flexibility. The ultra-smaller size of these particles as compared to RBCs lets them flow even when there is just a trickle of residual plasma and efficiently deliver oxygen to prevent tissue damage. We tested the hypothesis that Oxygent-PFC would attenuate post-SAH functional and anatomical impairments. Methods: Adult C57BL/6 wildtype mice were subjected to the endoperforation model of SAH followed by an i.v injection of Oxygent-PFC or saline (9ml/kg at 6h after SAH). At 48h after SAH, mice were tested for functional outcomes followed by blood collection through cardiac puncture. Thereafter, mice were transcardially perfused, and brains were harvested to assess various immunohistochemical and biochemical outcomes. Results and Conclusion: We found that SAH resulted in significant neurologic and motor deficits while Oxygent-PFC treatment attenuated these functional deficits. There was a significant neuronal death after SAH as compared with the sham group and Oxygent-PFC prevented neuronal death. Moreover, mitochondrial activity as assessed by OXPHOS was markedly decreased after SAH while Oxygent-PFC treatment significantly improved the mitochondrial activity as compared to the vehicle-treated SAH group. These data show that Oxygent-PFC treatment preserves mitochondrial activity, dimmish tissue damage, and improve functional outcomes. Our novel preliminary study in SAH encourages us to investigate the mechanism of action of Oxygent-PFC and a comprehensive preclinical trial to test its efficacy in different animal models of SAH.

Analysis of Plasma and Gas Characteristics According to the Recovery Process Using a New Alternative Gas

Perfluorocarbon (PFC) gas, which is predominantly used in the etching and chamber cleaning processes of semiconductor manufacturing, is very stable and remains on Earth for long periods. Moreover, it has a high global warming potential because it blocks the emission of radiant heat from the Earth and contributes to global warming. To mitigate these effects, the waste PFC gas can be recovered and reused, which also limits the unnecessary waste of resources. In this study, the liquid fluorocarbon C6F6, which has a high C/F ratio and exists as a liquid at room temperature, was selected as an alternative to PFC gas, and adsorption and recovery were performed through an adsorption module during the plasma process. To characterize the recovered gas, residual gas analysis was performed on the gases recovered during etching. In addition, optical emission spectroscopy and printed circuit board probes were used to characterize the plasma. Finally, the feasi-bility of the gas recovery process was evaluated by comparing the thicknesses of the CF polymers produced in Si and SiO2 using an ellipsometer. The results revealed that the C6F6 had similar characteristics before and after recovery, confirming that this gas can be reused and is suitable for use in semiconductor manufacturing as a green alternative.

Mitochondria-Targeting and Oxygen Self-Supplying Eccentric Hollow Nanoplatform for Enhanced Breast Cancer Photodynamic Therapy

Photodynamic therapy (PDT) has received increasing attention for tumor therapy due to its minimal invasiveness and spatiotemporal selectivity. However, the poor targeting of photosensitizer and hypoxia of the tumor microenvironment limit the PDT efficacy. Herein, eccentric hollow mesoporous organic silica nanoparticles (EHMONs) are prepared by anisotropic encapsulation and hydrothermal etching for constructing PDT nanoplatforms with targeting and hypoxia-alleviating properties. The prepared EHMONs possess a unique eccentric hollow structure, a uniform size (300 nm), a large cavity, and ordered mesoporous channels (2.3 nm). The EHMONs are modified with the mitochondria-targeting molecule triphenylphosphine (CTPP) and photosensitizers chlorin e6 (Ce6). Oxygen-carrying compound perfluorocarbons (PFCs) are further loaded in the internal cavity of EHMONs. Hemolytic assays and in vitro toxicity experiments show that the EHMONs-Ce6-CTPP possesses very good biocompatibility and can target mitochondria of triple-negative breast cancer, thus increasing the accumulation of photosensitizers Ce6 at mitochondria after entering cancer cells. The EHMONs-Ce6-CTPP@PFCs with oxygen-carrying ability can alleviate hypoxia after entering in the cancer cell. Phantom and cellular experiments show that the EHMONs-Ce6-CTPP@PFCs produce more singlet oxygen reactive oxygen species (ROSs). Thus, in vitro and in vivo experiments demonstrated that the EHMONs-Ce6-CTPP@PFCs showed excellent treatment effects for triple-negative breast cancer. This research provides a new method for a targeting and oxygen-carrying nanoplatform for enhancing PDF effectiveness.

Insights into the prediction of the liquid density of refrigerant systems by artificial intelligent approaches

This study presents a novel model for accurately estimating the densities of 48 refrigerant systems, categorized into five groups: Hydrofluoroethers (HFEs), Hydrochlorofluorocarbons (HCFCs), Perfluoroalkylalkanes (PFAAs), Hydrofluorocarbons (HFCs), and Perfluoroalkanes (PFAs). Input variables, including pressure, temperature, molecular weight, and structural groups, were systematically considered. The study explores the efficacy of both the multilayer perceptron artificial neural network (MLP-ANN) and adaptive neuro-fuzzy inference system (ANFIS) methodologies in constructing a precise model. Utilizing a comprehensive dataset of 3825 liquid density measurements and outlier analysis, the models achieved R2 and MSE values of 0.975 & 0.5575 and 0.967 & 0.7337 for MLP-ANN and ANFIS, respectively, highlighting their remarkable predictive performance. In conclusion, the ANFIS model is proposed as an effective tool for estimating refrigerant system densities, particularly advantageous in scenarios where experimental measurements are resource-intensive or sophisticated analysis is required.

Self-Assembled Fluorinated Nanoparticles as Sensitive and Biocompatible Theranostic Platforms for 19F MRI.

Theranostics is a novel paradigm integrating therapy and diagnostics, thereby providing new prospects for overcoming the limitations of traditional treatments. In this context, perfluorocarbons (PFCs) are the most widely used tracers in preclinical fluorine-19 magnetic resonance (19F MR), primarily for their high fluorine content. However, PFCs are extremely hydrophobic, and their solutions often display reduced biocompatibility, relative instability, and subpar 19F MR relaxation times. This study aims to explore the potential of micellar 19F MR imaging (MRI) tracers, synthesized by polymerization-induced self-assembly (PISA), as alternative theranostic agents for simultaneous imaging and release of the non-steroidal antileprotic drug clofazimine. In vitro, under physiological conditions, these micelles demonstrate sustained drug release. In vivo, throughout the drug release process, they provide a highly specific and sensitive 19F MRI signal. Even after extended exposure, these fluoropolymer tracers show biocompatibility, as confirmed by the histological analysis. Moreover, the characteristics of these polymers can be broadly adjusted by design to meet the wide range of criteria for preclinical and clinical settings. Therefore, micellar 19F MRI tracers display physicochemical properties suitable for in vivo imaging, such as relaxation times and non-toxicity, and high performance as drug carriers, highlighting their potential as both diagnostic and therapeutic tools.

Silicon ring resonator with ZIF-8/PDMS cladding for sensing dissolved CO2 gas in perfluorocarbon solutions

Precise measurement of dissolved CO2 gas concentration in perfluorocarbon (PFC) solution is essential to the implementation and understanding of extra-pulmonary gas exchange with liquid ventilation. While electrochemical and optochemical sensing methods are widely used for dissolved CO2 sensing in aqueous solution, dissolved CO2 sensing in the PFC solution remains largely unexplored. We report a refractive index-based silicon photonic sensor for monitoring dissolved CO2 gas in the PFC solution. The sensor employs a high-Q silicon ring resonator with ZIF-8 cladding for selective and sensitive detection of dissolved CO2 gas. Further, a gas-permeable PDMS coating layer is applied to the ZIF-8 cladding for enabling gas diffusion between the PFC solution and the ZIF-8. The PDMS layer does not dissolve in PFC and its hydrophobic properties help protect the ZIF-8 from potential damage caused by aqueous body fluids in the PFC solution during the liquid ventilation process. The fabricated sensor exhibits stable and repeatable responses in the PFC solution with a fine resolution of ∼0.16 CO2 vol%, good selectivity for dissolved CO2 over dissolved O2, and a fast response time of ∼1.9 min, enabling reliable monitoring of dissolved CO2 gas level changes in the PFC solution.

Vaporization of perfluorocarbon attenuates sea-water-drowning-induced acute lung injury by deactivating the NLRP3 inflammasomes in canines.

Seawater-drowning-induced acute lung injury (SD-ALI) is a life-threatening disorder characterized by increased alveolar-capillary permeability, an excessive inflammatory response, and refractory hypoxemia. Perfluorocarbons (PFCs) are biocompatible compounds that are chemically and biologically inert and lack toxicity as oxygen carriers, which could reduce lung injury in vitro and in vivo. The aim of our study was to explore whether the vaporization of PFCs could reduce the severity of SD-ALI in canines and investigate the underlying mechanisms. Eighteen beagle dogs were randomly divided into three groups: the seawater drowning (SW), perfluorocarbon (PFC), and control groups. The dogs in the SW group were intratracheally administered seawater to establish the animal model. The dogs in the PFC group were treated with vaporized PFCs. Probe-based confocal laser endomicroscopy (pCLE) was performed at 3h. The blood gas, volume air index (VAI), pathological changes, and wet-to-dry (W/D) lung tissue ratios were assessed. The expression of heme oxygenase-1 (HO-1), nuclear respiratory factor-1 (NRF1), and NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasomes was determined by means of quantitative real-time polymerase chain reaction (qRT-PCR) and immunological histological chemistry. The SW group showed higher lung injury scores and W/D ratios, and lower VAI compared to the control group, and treatment with PFCs could reverse the change of lung injury score, W/D ratio and VAI. PFCs deactivated NLRP3 inflammasomes and reduced the release of caspase-1, interleukin-1β (IL-1β), and interleukin-18 (IL-18) by enhancing the expression of HO-1 and NRF1. Our results suggest that the vaporization of PFCs could attenuate SD-ALI by deactivating NLRP3 inflammasomes via the HO-1/NRF1 pathway.

Emulsifying mechanisms of phospholipids in high-pressure homogenization of perfluorocarbon nanoemulsions.

Phospholipids are the most ubiquitous emulsifiers in foods, beverages, pharmaceuticals, and human physiology, but their emulsifying properties are extremely complex. Differential analyses of mechanisms contributing to their functionality are presented in a modular approach. Addition of cholesterol to a natural phospholipid blend disturbs emulsification beyond specific thresholds for size, polydispersity and formation of emulsifying monolayers. Beyond a ratio of lipid concentration to dispersed volume of 1 mM per 1% (v/v) of perfluorocarbon (PFC), phospholipids no longer form monolayers but instead form triple layers that emulsify the PFC. Using synthetic saturated phospholipids, it can be shown that emulsification is most successful for fatty acids closely below their main transition temperature. Phospholipid head groups are more effective for emulsification the more they increase the area per molecule or the zeta potential. Including a comparison with literature results, it can be shown that high molecular weight emulsifiers like proteins are not dependent on the ratio of viscosities η of the dispersed phase to the continuous phase, ηD/ηC. In contrast, smaller molecular weight emulsifiers like phospholipids show a mild increase in effectiveness with rising ηD/ηC, although this increase is not as strong as that observed for low molecular weight detergents. Ruptures of highly resistant emulsifying interfacial layers obviously lead to direct droplet break-up, irrespective of the resistance of a high-viscosity droplet. The lower the break-up resistance of an emulsifier, the more is it governed by the bulk viscosity of the dispersed phase. Our results allow the preparation of a phospholipid-stabilized emulsion with optimized emulsification settings for pharmaceutical applications.

Multiplex Ultrasound Imaging of Perfluorocarbon Nanodroplets Enabled by Decomposition of Postvaporization Dynamics.

Despite the real-time, nonionizing, and cost-effective nature of ultrasound imaging, there is a dearth of methods to visualize two or more populations of contrast agents simultaneously─a technique known as multiplex imaging. Here, we present a new approach to multiplex ultrasound imaging using perfluorocarbon (PFC) nanodroplets. The nanodroplets, which undergo a liquid-to-gas phase transition in response to an acoustic trigger, act as activatable contrast agents. This work characterized the dynamic responses of two PFC nanodroplets with boiling points of 28 and 56 °C. These characteristic responses were then used to demonstrate that the relative concentrations of the two populations of PFC nanodroplets could be accurately measured in the same imaging volume within an average error of 1.1%. Overall, the findings indicate the potential of this approach for multiplex ultrasound imaging, allowing for the simultaneous visualization of multiple molecular targets simultaneously.

Effect of Phase-Change Nanodroplets and Ultrasound on Blood-Brain Barrier Permeability In Vitro.

Phase-change nanodroplets (PCND;NDs) are emulsions with a perfluorocarbon (PFC) core that undergo acoustic vaporisation as a response to ultrasound (US). Nanodroplets change to microbubbles and cavitate while under the effect of US. This cavitation can apply forces on cell connections in biological barrier membranes, such as the blood-brain barrier (BBB), and trigger a transient and reversible increased permeability to molecules and matter. This study aims to present the preparation of lipid-based NDs and investigate their effects on the brain endothelial cell barrier in vitro. The NDs were prepared using the thin-film hydration method, followed by the PFC addition. They were characterised for size, cavitation (using a high-speed camera), and PFC encapsulation (using FTIR). The bEnd.3 (mouse brain endothelial) cells were seeded onto transwell inserts. Fluorescein with NDs and/or microbubbles were applied on the bEND3 cells and the effect of US on fluorescein permeability was measured. The Live/Dead assay was used to assess the BBB integrity after the treatments. Size and PFC content analysis indicated that the NDs were stable while stored. High-speed camera imaging confirmed that the NDs cavitate after US exposure of 0.12 MPa. The BBB cell model experiments revealed a 4-fold increase in cell membrane permeation after the combined application of US and NDs. The Live/Dead assay results indicated damage to the BBB membrane integrity, but this damage was less when compared to the one caused by microbubbles. This in vitro study shows that nanodroplets have the potential to cause BBB opening in a similar manner to microbubbles. Both cavitation agents caused damage on the endothelial cells. It appears that NDs cause less cell damage compared to microbubbles.

A Cyclic Etching Process Using HFE-347mcc3 as a Lower-GWP Alternative to Perfluorocarbons for High-Aspect-Ratio SiO2 Features

As circuits continue to integrate at higher levels, the critical dimensions of DRAM and 3D-NAND are decreasing, leading to an increase in aspect ratios of various features such as contact holes and via holes in DRAM, and channel holes of stack layers in 3D-NAND. This trend has made the process of etching high-aspect-ratio SiO2 features more challenging. To achieve this, it is necessary to satisfy specific conditions including high selectivity to the mask or the underlayer film and the anisotropic etch profiles.Perfluorocarbons (PFCs) such as CF4 and c-C4F8 are commonly used for SiO2 etching. PFCs form a thicker steady-state fluorocarbon film on Si than SiO2, leading to high SiO2/Si selectivity. In addition, PFCs enable anisotropic etching since a passivation layer is formed on the sidewall, preventing lateral etching of the sidewall by chemical etchants.However, PFCs are a representative greenhouse gas with a high global warming potential (GWP) compared to CO2, causing significant adverse effects on global warming. Therefore, there have been efforts to reduce greenhouse gas emissions, such as setting goals for greenhouse gas reduction by each country through the Paris Agreement in 2015. Semiconductor manufacturers have also committed to reducing greenhouse gas emissions per silicon substrate area by 30% compared to 2010. In this regard, various studies are being conducted to develop a SiO2 etching process using alternative materials with lower GWP than PFCs. Fluorinated ethers and fluorinated alcohols are potential substitutes due to their low GWPs and short lifetimes. For example, heptafluoropropyl methyl ether (HFE-347mcc3) has a GWP of ~530 and an atmospheric lifetime of 5.2 years, significantly lower than those of PFCs.During etching of SiO2, the mask is susceptible to damage and corrosion by ions, resulting in various pattern deformations such as bowing, necking, and striation. These deformations adversely affect the miniaturization of the DRAM structure by reducing the process margin between holes and have a negative influence on the electrical characteristics of the device, such as contact resistance, line edge roughness, and line width roughness.To prevent these pattern deformations, the cyclic etching process that repeats the passivation layer deposition step and SiO2 pattern etching step was devised. A fluorocarbon film is deposited on the mask to protect it, then SiO2 is etched. The fluorocarbon film is deposited again to reinforce the mask and damaged fluorocarbon film during the etching process, and then SiO2 etching step is repeated to achieve the high-aspect-ratio SiO2 features.In this study, the cyclic etching process was conducted using HFE-347mcc3 as a lower-GWP alternative to PFCs to etch SiO2 contact holes. The effect of the duration of each step on the etch profile was investigated by adjusting the duration of the deposition and etching steps. This work demonstrated the feasibility of using HFE-347mcc3 as a lower-GWP alternative to PFCs for cyclic etching of SiO2 contact holes to obtain anisotropic etch profiles.

Neodymium Metal Production Via Chloride Based Molten-Salt Electrolysis

The extraction and purification of metals such as aluminum has relied on the electrowinning process for decades. The Hall-Héroult process, developed in 1885, utilizes a molten salt electrolyte to electrochemically produce aluminum metal (Al) and carbon dioxide (CO2).1–3 Similar molten salt techniques exist for a variety of other metals including the rare earth metal Neodymium (Nd). Neodymium has seen significant increases in demand from increased production of wind turbines, electric vehicles, and hard disk drives that use neodymium–iron–boron (Nd–Fe–B) permanent magnets. 4,5 The current procedure for neodymium processing uses a neodymium and lithium fluoride molten salt electrolyte with a sacrificial carbon anode to convert neodymium oxide (Nd2O3) and carbon to neodymium metal and CO2.4,6 As an unfortunate byproduct of the fluoride containing molten salt, perfluorocarbons (PFCs) can also be produced simultaneously. The formation of PFCs combined with the emission of other greenhouse gases (CO,CO2) makes the current process dangerous and undesirable from an environmental standpoint. Due to this, few places currently produce neodymium metal and virtually none is produced in the United States, creating supply chain risks with dire consequences.5 An alternative molten salt process has been proposed where rather than directly converting neodymium oxide to neodymium metal, the oxide is first converted to chloride salt form by reaction with hydrochloric acid. The neodymium salt is then dissolved into a chloride salt based melt and neodymium is electroplated via the below set of reactions.7,8 Cathode: 2NdCl3 + 6e- → 2Nd(solid) + 6Cl- Anode: 6Cl- → 3Cl2 + 6e- Overall: 2NdCl3 → 2Nd(solid) + 3Cl2 This process has several distinct advantages. The chlorine reaction eliminates the need for a sacrificial anode material as well as the production of carbon dioxide. The chloride based molten salt also eliminates the formation of PFCs. The chlorine is then recycled to make more hydrochloric acid for use in converting neodymium oxide to chloride.This talk focuses on recent advances to improve purity and lower energy consumption (kWh/kg). We evaluate anode and cathode behavior during this neodymium chloride molten salt process. Over-potential and stability of various anode materials are investigated in order to minimize energy consumption and ensure long life of process materials. A new stable analytic cathode is demonstrated which is lowers chlorine over-potential by more than 200 mV at current density of 250 mA/cm2.The effect of various plating conditions such as current density and substrate material are investigated to determine impact on deposit quality, coulombic efficiency, and metal purity. Highly porous Nd deposits are known to form in chloride molten salt but are undesirable due to the energy required to separate out the high volume fraction of salt remaining in the solid sponge. Effects of temperature and electrolyte composition on deposit morphology are investigated and improvements toward densifying the sponge to minimize post electrolysis purification are reported. This proof of concept work aims to develop a safe, sustainable and environmentally friendly path towards large scale production of rare earth elements. Reactor design and cathode efficiency results are based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy under the Advanced Manufacturing Office, Award Number DE-EE0009434. Anode design work was supported through the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government. Portions of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. T. R. Beck, Electrochem. Soc. Interface, 23, 36–37 (2014).G. G. Botte, Electrochem. Soc. Interface, 23, 49–55 (2014).W. E. Haupin, J. Chem. Educ., 60, 279–282 (1983).M. F. Chambers and J. E. Murphy, Electrolytic production of neodymium metal from a molten chloride electrolyte.B. Sprecher, R. Kleijn, and G. J. Kramer, Environ. Sci. Technol., 48, 9506–9513 (2014).V. S. Cvetković et al., Met. 2020, Vol. 10, Page 576, 10, 576 (2020).R. Akolkar, J. Electrochem. Soc., 169, 043501 (2022).D. Shen and R. Akolkar, J. Electrochem. Soc., 164, H5292–H5298 (2017).

Amorphization of Inorganic Solid Electrolyte Interphase Components and Its Impact on Enhancing Their Transport and Mechanical Properties.

The safety and cycle life of lithium-ion batteries (LIBs) are largely determined by the solid electrolyte interphase (SEI) formed on the surface of the anode. However, there is still a lack of understanding regarding the structure and properties of the individual SEI components. Among others, lithium oxide (Li2O), lithium carbonate (Li2CO3), and lithium fluoride (LiF) are known to be the main components of the inorganic SEI layer in conventional LIBs, but their intrinsic protective roles remain controversial. Herein, we present the transformational effects of their amorphous phase on the mechanical and transport characteristics, based on first-principles calculations. Our studies clearly demonstrate that their amorphous phases exhibit significantly improved Li-ion conductivity when compared to the crystalline structures. Additionally, among them, amorphous LiF emerges as a frontrunner for fast Li+ ion transportation, reversing the conventionally understood hierarchy. Under ambient conditions, the amorphous phases of LiF, Li2O, and Li2CO3 are thermodynamically unstable and tend to undergo recrystallization. However, this work highlights that exceptionally ductile and resilient amorphous phases can form if SEI formation and growth would involve some admixing of lithiophilic impurities like nitrogen (N) within the host matrices.

Perfluorocarbon Nanoparticles Incorporating Ginkgolide B: Artificial O2 Carriers with Antioxidant Activity and Antithrombotic Effect.

Ischemic stroke primarily leads to insufficient oxygen delivery in ischemic area. Prompt reperfusion treatment for restoration of oxygen is clinically suggested but mediates more surging reactive oxygen species (ROS) generation and oxidative damage, known as ischemia-reperfusion injury (IRI). Therefore, the regulation of oxygen content is a critical point to prevent cerebral ischemia induced pathological responses and simultaneously alleviate IRI triggered by the sudden oxygen restoration. In this work, we constructed a perfluorocarbon (PFC)-based artificial oxygen nanocarrier (PFTBA-L@GB), using an ultrasound-assisted emulsification method, alleviates the intracerebral hypoxic state in ischemia stage and IRI after reperfusion. The high oxygen solubility of PFC allows high oxygen efficacy. Furthermore, PFC has the adhesion affinity to platelets and prevents the overactivation of platelet. The encapsulated payload, ginkgolide B (GB) exerts its anti-thrombosis by antagonism on platelet activating factor and antioxidant effect by upregulation of antioxidant molecular pathway. The versatility of the present strategy provides a practical approach to build a simple, safe, and relatively effective oxygen delivery agent to alleviate hypoxia, promote intracerebral oxygenation, anti-inflammatory, reduce intracerebral oxidative stress damage and thrombosis and caused by stroke.

Characterization and transport properties of ceramic filler incorporated natural rubber composites

AbstractCrystalline glass–ceramic fillers were prepared from calcium carbonate, silica, alumina, and calcium fluoride by heating and subsequent quenching in cold water. The fillers were incorporated into natural rubber (1,4‐cis‐polyisoprene) and the filled rubber composites were crosslinked with sulfur in the presence of different rubber additives. The unfilled and filled rubber composites were characterized. The transport properties of benzene, toluene, and p‐xylene (BTX) through the rubber composites were studied in terms of sorption, diffusion, permeation, and mass transfer coefficients. The effect of the ceramic fillers on the mechanical, thermal and transport properties were studied. The sorption data at different temperatures were used for calculating activation energy of diffusion, permeation, free energy, and enthalpy of sorption. The BTX remained in the liquid state within the composite matrix as evident from negative ΔS. The diffusion coefficient (D) and mass transfer coefficient (kmtc) of BTX decreased with the increase in filler loading. Accordingly, for the transport of BTX the unfilled rubber showed a D (D × 107 cm2/s) and mass transfer coefficient (kmtc × 104 cm/s) of 5.67/3.97/2.96 and 7.71/7.08/7.04, respectively which decreased to 5.06/2.95/2.57 and 7.53/6.95/6.90, respectively for the composite containing 50 wt.% ceramic filler.